Datasets:

clinicalnlplab

/

PubmedSumm_train

like 1

Follow

Clinical NLP Lab 22

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the problem is growing so rapidly that it is projected to be the seventh leading cause of death by 2030 . the escalating burden of diabetes has already surfaced in low and middle income countries ( lmcs ) where four out of five people with diabetes are currently living . recent population based studies conducted in nepal have also reported a growing prevalence of diabetes among urban , middle , and elderly population . depression , one of the major comorbid conditions associated with chronic diseases , has a bidirectional relationship with diabetes . the presence of depression is two times more common in people with diabetes than in those without diabetes . therefore , the coexistence of depression among people with diabetes worsens the disease outcomes . in diabetic patients , depression has been linked with the multiple factors like female sex , younger age , not having a spouse , poor social support , and low socioeconomic status , among others . most importantly , depression is associated with the perception of patients about their disease . illness representation or perception reflects the patients ' own views about the cause ( beliefs about how the disease occurred ) , illness identity ( beliefs about how the disease should look like , by relating to the symptoms ) , illness consequences ( impact of the disease on quality of life , relationships , and work ) , timeline ( whether the disease is of long or short duration or has cyclical onset of symptoms ) , and cure or control ( whether the illness can be controlled by patient 's behavior or treatment module ) . positive illness perception is established when the illness is viewed as a normal part of life . curtailed information about the disease collected from the social interactions , from the authoritative sources such as doctors , from patients , and from his / her own experiences forms an overview regarding the disease . such image may generate the pessimistic view about disease that can lead to psychological disorders . on the contrary , the appropriate knowledge about the condition may provide healthy judgment regarding behaviors related to the disease . literatures have shown relationship between illness perception and depression in cardiovascular disease ( cvd ) and renal diseases . therefore , this research aimed to identify the relationship between illness perception and depressive symptoms in patient with diabetes . this was an analytical cross - sectional study conducted between december 2013 and june 2014 in clinical settings in kathmandu , nepal . study sites were tribhuvan university teaching hospital , maharajgunj ; diabetes , thyroid care and endocrinology center , kupondole ; and diabetic society clinic , jamal . sites were selected purposively as they were the well - known diabetic treatment centers in nepal . study participants were patients with the diagnosis of type 2 diabetes mellitus attending study sites during the study period . sample size was calculated using z pq / d formula at 95 % confidence interval and 5 % allowable error . the estimated prevalence of depression among persons with diabetes was assumed to be 40.3 % , based on previous similar hospital based study . samples were proportionately allocated to each study site with respect to the average number of patient visits to the centers in previous months . participants between 20 and 70 years of age attending study sites with present history of diabetes of at least six months of duration were selected for the study . the total number of eligible patients registered in all study sites was 1200 . among them , every third participant was enrolled in the study . patients with diabetic complications like neuropathy , nephropathy , retinopathy , autonomic neuropathy , and so forth were excluded because of their independent association with depression . likewise , those with the previous episode of depression or using any antidepressant medication were also excluded . ethical approval was taken from the nepal health research council ( nhrc ) , ramshah path , kathmandu , nepal . they were well informed about their right to withdraw from the study at any time . participants were also assured that all personal details would be confidential . considering no more than minimal risk in research participationconsent procedure was approved by ethical review board of the nhrc based on national ethical guidelines for health research in nepal . the first section of the data collection tools was structured questionnaires , designed to collect the sociodemographic data . occupations were recorded in different categories : job ( government or nongovernment ) , business , farming , and so forth . it utilizes the level of education , household income , and occupation for calculating individual 's socioeconomic status . participants were also requested to report the diabetes duration , use of antidiabetic medications ( insulin / pills ) including alcohol consumption , and cigarette smoking habit . the well validated illness perception questionnaire - revised ( ipq - r ) was used for assessing the illness perception . firstly , diabetes identity was assessed using 14 commonly experienced symptoms like headache , joint stiffness , weight loss , and so forth . for each symptom , participants were asked to indicate ( a ) if they had experienced this symptom since their diabetes and ( b ) whether they believed the symptom was related to their diabetes . the responses were recorded as yes / no . the sum of the yes - rated symptoms on the second scale comprises the diabetes identity subscale . timeline acute / chronic , timeline cyclical , consequences , personal control , treatment control , illness coherence , and emotional representations were assessed in the second section . altogether 38 items were presented with a five - point response scale : strongly disagree , disagree , neither agree nor disagree , agree , and strongly agree . the scale was scored accordingly : strongly disagree = 1 , disagree = 2 , neither agree nor disagree = 3 , agree = 4 , and strongly agree = 5 . identity was scored as yes or no , where yes = 1 and no = 0 . it contained 21 questions , each answer being scored on a scale value of 0 to 3 . for clinical interpretation , presence of depressive symptoms was defined as a bdi - ii score 14 . we opted to use the tool in our study , considering its latest improvisation as per dsm - iv criteria for major depression . bdi - ii omits items relating to weight loss , body image , hypochondria , and working difficulty and has added items relating to agitation , worthlessness , difficulty concentrating , and energy loss compared to earlier versions in order to assess the intensity of depression . the questionnaires were translated into nepali by two multilingual researchers individually . principal investigator mediated the discussion between two translators and facilitated coming up with single version . another bilingual researcher back - translated it into english and validated it with the original one . two experts from psychology department of tribhuvan university consolidated the different versions of translations making them equivalent to source version . effort was made to ensure that the translation carried the same meaning as the original version while also being sensitive to the nuances of nepali language . the translated version was pretested among 20 respondents . for assessing reliability of both instruments ( illness perception , bdi - ii ) , we calculated reliability coefficients ( cronbach 's alpha ) for all nine subscales of illness perception and bdi - ii using the study dataset . five research assistants were chosen and trained to administer the questionnaire in seven - day training program . they were asked to repeat the mock interviews under direct supervision of investigators until desired standards were achieved . collected data were entered in epidata v. 2.1 and exported to spss v. 16.0 for further analysis . chi - square test was conducted to compare the proportions of depressive and nondepressive symptoms among respondents across the sociodemographic strata . spearman 's correlation was applied for analyzing the relationship between illness perception and depression scores . presence of depressive symptoms was considered as dependent variable with dichotomous outcomes : 0 = absent , 1 = present . those variables that were significantly associated with depressive symptoms in bivariate analyses were entered into multivariable model through stepwise ( forward conditional ) method . we also conducted stepwise backward conditional method , where we got exactly the same result as in forward conditional method . the probabilities for entry and removal of variable in each step were set as 0.05 and 0.1 , respectively . after excluding 11 participants who did not respond well , total participants were 379 , with 50.1 % females and 49.9 % males . the mean age of the respondents was 54.810.6 years with median duration of diabetes of 8.7 years ( iqr = 10 years ) . the majority of the participants had age between 51 and 60 years ( 34.3 % ) , were from nuclear family ( 85.8 % ) and urban area ( 84.7 % ) , and belonged to newar ethnic group ( 47 % ) and hinduism ( 87.1 % ) . most of respondents were homemakers ( 29.8 % ) and from lower socioeconomic status ( 73.9 % ) ( table 1 ) . reliability coefficients ( cronbach alpha ) were computed for each of the ipq - r subscales and the bdi - ii score . among nine illness perception subscales , bdi - ii scale , however , showed an excellent reliability with high cronbach alpha ( = 0.869 ) ( table 2 ) . the prevalence of depressive symptoms among the respondents was 44.1 % ( 95 % ci : 39.1 , 49.1 ) . it was significantly high among females compared to their male counterparts ( p 0.001 ) . also , proportions of depressive symptoms were high among homemakers ( 65.4 % ) , patients with lower socioeconomic status ( 70.9 % ) , and age group 6170 years ( 58.2 % ) ( table 3 ) . the average score of personal control was comparatively higher than mean score of other subscales ( table 3 ) . it is because the majority ( 75 % ) of participants agreed that there was a lot which they could do to control their symptoms . most of the respondents ( 82 % ) also believed the course of diabetes depended on them . in contrast to that , cyclical timeline had the lowest average score among all subscales . a large proportion of respondents ( 43 % ) disagreed that the symptoms of diabetes changed a great deal from day to day in cyclical nature . spearman correlation analysis found that identity ( r = 0.525 , p 0.001 ) , acute timeline ( r = 0.115 , p = 0.025 ) and cyclical timeline ( r = 0.337 , p 0.001 ) , consequences ( r = 0.511 , p 0.001 ) , emotional representation ( r = 0.636 , p 0.001 ) , and causes ( r = 0.366 , p 0.01 ) components had a significant positive correlation with bdi - ii scores ( table 4 ) . contrarily , treatment control ( r = 0.250 , p 0.001 ) and illness coherence ( r = 0.446 , p 0.001 ) had a negative relationship with depressive symptoms ( table 4 ) . in a separate spearman correlation analysis , duration of diabetes had no significant relationship with depression scores ( r = 0.013 , p = 0.802 ) . in multivariable analysis , all explanatory variables significant in bivariate analysis were entered by a stepwise ( forward conditional ) method into binary logistic regression model . seven variables , emotional representation ( = 0.214 , p 0.001 ) , identity ( = 0.196 , p 0.001 ) , no formal education ( = 1.959 , p = 0.01 ) , age ( = 0.036 , p = 0.016 ) , illness coherence ( = 0.109 , p = 0.007 ) , mode of treatment ( = 0.9 , p = 0.047 ) , and consequences ( = 0.093 , p = 0.049 ) , were finalized as significant predictors of depressive symptoms ( table 5 ) . multivariable analysis showed that one - year increase in age shifted odds of having depressive symptoms by 1.037 . people without formal education had seven times higher chance of suffering from depressive symptoms than people with master 's degree . in the same way , treatment with insulin had higher likelihood of getting depressive symptoms than the people taking oral medication . people using insulin for treatment of their diabetes had tendency to suffer from depressive symptoms 2.3 times higher than people on medication . likewise , illness perception related to identity , consequences , and emotional representation about diabetes had positive relationship with depressive symptoms . one - unit increase in identity , consequences , and emotional representation heightened the likelihood of getting depressive symptoms among diabetes patients by 21 % , 9.8 % , and 23.9 % , respectively . on the other hand , the same amount increase in illness coherence was responsible for 10 % decrease in depressive symptoms among diabetes patients . this result was in line with the study conducted in nepal in similar setting where the prevalence was seen to be 40.3 % . this rate was also comparable to prevalence of depression ( 36.6 % ) as reported in a meta - analysis of studies among persons with diabetes in clinical settings . our study showed that female respondents with lower socioeconomic status and lower educational background and homemakers were significantly associated with depressive symptoms . various studies have reported that female , elderly people and single women are more susceptible to anxiety and depression . a meta - analysis including 39 studies also demonstrated that the prevalence of depression in patients with diabetes was significantly high in women compared to men . similarly , a study conducted in hospital settings in india pointed out that depression was more prevalent in female as compared to males . the high proportion of depressive symptoms in women might have been observed because of the presence of more females from low socioeconomic group , having less educational status , and spending most time as homemaker compared to men . besides , low socioeconomic status , having less education , and spending most time as homemaker have their association with depression among diabetic patients independently . this study clearly indicated that depressive symptoms did not have a significant disproportional distribution among different religions , family type , and ethnic groups . in the same way , this study also did not find a significant association of alcohol consumption and smoking with depressive symptoms , which is consistent with previous studies conducted in similar setting in kathmandu , nepal , and tlemcen , algeria . similarly , presence of depressive symptoms was significantly high among the people who were using insulin for the treatment of diabetes compared to the participants using only medications . they might have perceived insulin treatment as the severity of condition as well as the burden to their daily activities . and al - amer et al . concluded that taking insulin for controlling diabetes had significant association with depression . our study also could not show a significant relationship between depressive symptoms and duration of diabetes . this was consistent with other studies that reported no significant relationship of the duration of diabetes with depression . our study demonstrated that illness perception of diabetic respondents was related to depressive symptoms they had . all the components of illness perception except personal control had significant relationship with depressive symptoms . this suggested participants with high depressive symptoms perceived diabetes as a condition having more symptoms . they also believed that their illness was more severe and cyclical in nature , had less effective treatment control , possessed more serious consequences , was less understandable , and consisted of many causal factors . in comparison to respondents having no depressive symptoms , they also expressed high emotional response . these findings were consistent with another study conducted among patients having end stage of renal disease that reported a significant corelation of identity , cyclical nature , consequences , personal control , treatment control , illness coherence , emotional response , and causes with depression . also , in researches conducted in rheumatoid arthritis and cardiac patients , perceiving serious illness consequences had negatively been correlated with depression . our study could not substantiate the same study that reported personal control had a significant relation with depressive symptoms . in our study , we found the majority of the participants believed they could control their symptoms . irrespective of presence of strong confidence over the personal control of diabetes among the participants , the reason behind not having its significant relationship with depressive symptoms remained unclear . this study also identified the illness identity , consequences , emotional representations , and coherence as the significant predictors of depressive symptoms . patients who perceived more symptoms ( identity ) , more consequences , high emotional response , and less understanding ( coherence ) of diabetes were likely to have more depressive symptoms than others . findings were suggestive of the fact that patients were more likely to get depressed when they knew less about their condition . similarly , patients with high depressive symptoms were likely to experience many symptoms of diabetes that were , in fact , not related to it . according to leventhal 's model of self - regulation , patients make their own lay views about disease after experiencing the symptoms and that cognition shapes their coping behaviors . therefore , familiarity with the symptoms and complications of any disease can make the patient more confident to deal with it , whereas poor perception leads to maladaptive outcomes of psychological distress . overall , the current study identified a relationship between illness perception and depressive symptoms among diabetic patients . this study is the first to establish their relationship among persons with diabetes in nepal . it has major implication for the development of patient centered intervention in prevention and management of depressive symptoms among nepalese diabetic patients . addressing illness perception early on persons with diabetes can provide the opportunity to improve their beliefs and can achieve significant positive influences on disease outcomes . it does not uncover the relationship of illness perception and glycemic control in diabetic patients . as many studies reported the significant association of glycemic control with depression , understanding the tripartite relationship of illness perception , glycemic control , and depression among diabetic patients could be an interesting area of study in future . similarly , the poor internal consistency of treatment control and personal control ipq - r subscales is also concerning limitation of the study . lastly , samples were taken from clinical settings and could not represent community as a whole ; a community based study is warranted for better representation . this study underlines the importance of understanding of illness perception for preventing depressive symptoms that paves the way for effective treatment and control among type 2 diabetics . providing information about the cause , pathology , complication , and overall treatment of disease can help to form a decent illness perception . hospital and treatment centers should create a favorable environment where patients can have access to authentic and appropriate information and check the viability of their illness perceptionsthis may help patients to follow active coping behaviors , ultimately preventing depressive symptoms and also helping in the treatment and control of diabetes .\noutput:\n" }, { "from": "agent", "value": "background . this study aimed to assess the relationship between illness perception and depressive symptoms among persons with diabetes . method . this was an analytical cross - sectional study conducted among 379 type 2 diabetic patients from three major clinical settings of kathmandu , nepal . results . the prevalence of depressive symptoms was 44.1 % ( 95 % ci : 39.1 , 49.1 ) . females ( p < 0.01 ) , homemakers ( p < 0.01 ) , 6170 age group ( p = 0.01 ) , those without formal education ( p < 0.01 ) , and people with lower social status ( p < 0.01 ) had significantly higher proportion of depressive symptoms than the others . multivariable analysis identified age ( = 0.036 , p = 0.016 ) , mode of treatment ( = 0.9 , p = 0.047 ) , no formal educational level ( = 1.959 , p = 0.01 ) , emotional representation ( = 0.214 , p < 0.001 ) , identity ( = 0.196 , p < 0.001 ) , illness coherence ( = 0.109 , p = 0.007 ) , and consequences ( = 0.093 , p = 0.049 ) as significant predictors of depressive symptoms . conclusion . our study demonstrated a strong relationship between illness perception and depressive symptoms among diabetic patients . study finding indicated that persons living with diabetes in nepal need comprehensive diabetes education program for changing poor illness perception , which ultimately helps to prevent development of depressive symptoms ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: lithium overdose can be associated with cardiac toxicity , especially in those with underlying heart disease . toxic levels of serum lithium are associated with cardiotoxic effects ranging from simple ecg disorders to dysrhythmias , cardiomyopathy and even acute myocardial infarction ( ami ) . a 62 - year - old woman was admitted to the emergency department due to weakness and acute chest pain . her ecg revealed st elevation in leads di , avl and v5 - 6 , with a ventricular rate of 80 bpm . the patient s blood lithium level was measured as 2.3 mmol / l ( n : 0.5 - 0.8 mmol / l ) , and her troponin i level was 0.892 ng / ml ( n : 0 - 0.01 ng / ml ) . coronary angiography produced normal findings , concurrent with the resolution of electrocardiographic abnormalities following elimination of lithium . the clinical course in the intensive care unit was uneventful and the patient was discharged on the seventh day . lithium intoxication should be considered in the differential diagnosis , especially in elderly patients on lithium therapy who are admitted to the emergency department with chest pain . lithium is an alkaline compound which was introduced in early 1900s for psychiatric disorders and is currently used in the treatment of bipolar affective disorder and depression . intoxications are relatively common due to the drug s narrow therapeutic index . its toxicity is characterized by neurological , gastrointestinal , renal , endocrine and cardiac problems ( 1 ) . patients with lithium intoxication ( li ) are classified as acute , acute - on - chronic and chronic poisoning . early symptoms of acute li mostly involve gastrointestinal problems , such as nausea and vomiting , but chronic symptoms are generally neurological and include ataxia , tremor , speech impairment and altered level of consciousness . a review of the literature revealed several case reports in which both therapeutic and toxic levels of serum lithium were associated with cardiotoxic effects ranging from simple ecg disorders to cardiomyopathy , arrhythmias and even acute myocardial infarction ( ami ) ( 2 ) . this report presents a patient admitted to the hospital with acute chest pain and st segment elevation associated with lithium therapy . a 62 - year - old woman was admitted to the emergency department suffering from weakness and acute chest pain during the preceding two hours . there were no records in the patient s history of any chronic diseases , including renal failure or hypo / hyperthyroidism . in fact , she had no remarkable medical history , except for being put on lithium 400 mg / day and duloxetine 20 mg / day , a week earlier , due to bipolar disorder . physical examination disclosed tremor in both hands and bilateral nystagmus . the patient s arterial blood pressure was 90/60 mmhg , with a heart rate of 78 bpm , a respiratory rate of 22 bpm , and a transcutaneous sao2 of 97 % . surface electrocardiography revealed st elevation in leads di , avl and v5 - 6 , with a ventricular rate of 80 bpm ( figure 1 ) . blood chemistry , including renal function tests and complete blood count were within normal limits . the patient s blood lithium level was measured as 2.3 mmol / l ( therapeutic range 0.5 to 0.8 mmol / l ) , and her troponin i level was 0.892 ng / ml ( n : 00.01 ng / ml ) . echocardiographic findings , including myocardial wall motions , pulmonary arterial pressure and ejection fractions were normal . the patient was admitted to the coronary intensive care unit . a subsequent coronary angiography performed within one hour of admission provided normal results ( figure 2 ) . this was concurrent with a resolution of electrocardiographic abnormalities accompanied by elimination of lithium , which suggested that the observed ecg changes were linked to li . the patient s lithium level , measured on the seventh day , was found to be within normal limits ( 0.6 mmol / l ) . the clinical course in the intensive care unit was uneventful , with the patient being provided medical treatment and then discharged . acute chest pain is among the most common complaints encountered in emergency settings . in such cases , thorough and systematic evaluationdiagnosis is based on the combination of a patient s entire medical history , physical examination and laboratory investigations . after ruling out cardiac and life - threatening conditions , the medical history should be carefully evaluated and use of medications should not be overlooked . this report describes a patient with acute chest pain whose ecg suggested ami while being treated with lithium carbonate , resulting in a threefold serum level increase above normal range . lithium - associated cardiotoxic effects can be seen even in therapeutic doses ( 3 ) . cardiac effects due to li include prolonged qt interval , atrioventricular block , sinus arrest and ventricular dysrhythmias ( 4 ) . lithium causes toxicity through several mechanisms , including depletion of intracellular potassium and displacement of intracellular calcium . these effects have been reported to cause a decreasing depolarization rate and ecg changes resembling hypokalemia , due to the interchangeability of lithium with intracellular potassium ( 5 ) . through these mechanisms , lithium triggers certain ecg changes , such as qt prolongation , t - wave abnormalities and st changes that masquerade as ami ( 6 ) . even though there are numerous reports of such ecg changes in the literature , cases with st elevation are rare . kayrak and colleagues found st segment elevation in inferior derivations as a result of lithium intoxication . as in our case , the myocardial wall motions and coronary angiography were found to be normal in echocardiography . since the patient had a normal coronary angiography and lacked myocardial wall motion irregularities , takotsubo cardiomyopathy was ruled out . cases of li are classified in terms of severity as acute , acute - on - chronic and chronic poisoning . pointed out that these kind of ecg disorders are encountered in chronic li ( 8 ) , which contrasts with the present case in that lithium therapy had only lasted for one week . li is reported more commonly in women than men , which is also the case in this paper . in addition , lithium is poorly tolerated by women and the elderly ( 9 ) . risk factors predisposing individuals to toxicity include diminished renal excretion of lithium due to advanced age - related renal impairment and lithium retention , secondary to nonsteroidal anti - inflammatory drugs , thiazide diuretics and the syndrome of inappropriate secretion of antidiuretic hormone ( siadh ) ( 10 ) . the recommended therapies in acute li include hemodialysis and whole bowel irrigation ( 10 , 11 ) . hydration treatment in li can decrease lithium reabsorption from the proximal tubule and increases its excretion . during initial therapy , replacement of fluids upto twice as much as the body s normal requirement are to be given as normal saline ( 6 ) . this treatment was followed by gradually lowered lithium levels , which returned to normal in a few days . resolution of electrocardiographic abnormalities in accordance with elimination of lithium suggests that ecg changes are linked to li . these findings can be misinterpreted as cardiac ischemia , and thus physicians staffed in primary care should be cautious on this issue . li should be considered in the differential diagnosis , especially in elderly patients on lithium therapy who present to the emergency department with chest pain . li should be considered in the differential diagnosis , especially in elderly patients on lithium therapy who present to the emergency department with chest pain .\noutput:\n" }, { "from": "agent", "value": "introductionlithium overdose can be associated with cardiac toxicity , especially in those with underlying heart disease . toxic levels of serum lithium are associated with cardiotoxic effects ranging from simple ecg disorders to dysrhythmias , cardiomyopathy and even acute myocardial infarction ( ami ) . this report describes a patient with ami accompanied by high blood levels of lithium.case presentationa 62 - year - old woman was admitted to the emergency department due to weakness and acute chest pain . her ecg revealed st elevation in leads di , avl and v5 - 6 , with a ventricular rate of 80 bpm . blood chemistry and complete blood count were within normal limits . the patient s blood lithium level was measured as 2.3 mmol / l ( n : 0.5 - 0.8 mmol / l ) , and her troponin i level was 0.892 ng / ml ( n : 0 - 0.01 ng / ml ) . coronary angiography produced normal findings , concurrent with the resolution of electrocardiographic abnormalities following elimination of lithium . the clinical course in the intensive care unit was uneventful and the patient was discharged on the seventh day.conclusionslithium intoxication should be considered in the differential diagnosis , especially in elderly patients on lithium therapy who are admitted to the emergency department with chest pain ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: metastatic tumor of the umbilicus has been well known as a sister mary joseph nodule ( smjn ) . the most common primary sites for metastases in women are reportedly the ovary ( 34 % ) , endometrium ( 12 % ) , colon / rectum ( 12 % ) , stomach ( 9 % ) , and pancreas ( 8 % ) ( dubreuil et al . , 1998 ) . smjn has an extremely poor prognosis , and the differential diagnosis thus requires histological examination ( dubreuil et al . , 1998 ) . nevertheless , umbilical tumors in women included endometriosis in 32.2 % , benign primary tumor in 29.7 % , metastatic tumor in 29.7 % , and malignant primary tumor in 8.4 % ( barrow , 1966 ) . umbilical endometriosis , one type of cutaneous endometriosis , is uncommon with an estimated incidence of 0.51.0 % among all cases of endometriosis ( latcher , 1953 ) . we report herein an unusual case of umbilical endometriosis and giant uterine leiomyoma with marked hydropic and cystic degeneration , in which magnetic resonance imaging ( mri ) was helpful in the diagnosis . a 47 - year - old woman , gravida 0 , was referred to our hospital with suspected uterine and ovarian tumors , and chief complaints of sudden pain in the right lower abdomen and fever ( 38.5 c ) . she had experienced abdominal distention for several years , with rapid growth over the last 6 months . the patient presented with a giant , soft abdominal mass associated with tenderness in the right lower quadrant ( fig .1 a ) , and a protruding navel , partially bluish - purple in coloration and involving a subcutaneous hard nodule , measuring 34 cm ( fig . the nodule was painless , and the patient had no history of umbilical bleeding or discharge . the white blood cell count was 10,540 / ml , hemoglobin was 12.5 g / dl , and c - reactive protein level was 4.32 mg / dl . level of carbohydrate antigen ( ca ) 125 was slightly elevated , but other tumor markers were within normal ranges : ca125 , 58.28 u / ml ; ca19 - 9 , 12.25 u / ml ; carcinoembryonic antigen ( cea ) , 0.4 ng / ml ; and lactate dehydrogenase ( ldh ) , 206 u / l . ultrasonography revealed marked enlargement of the uterus with two solid hypoechoic tumors measuring 14 cm and 11 cm in diameter and suspected to represent leiomyomas , two cystic tumors measuring 12 cm and 7 cm in diameter , and a large tumor containing abundant variable - sized cysts and surrounding the above tumors . color doppler ultrasonography showed poor blood flow in these tumors . mri revealed an umbilical tumor showing signal hypointensity on t2 - weighted imaging and slight signal hyperintensity on fat - suppressed t1 - weighting imaging with small foci of slightly signal hyperintensity on t2 - weighted imaging , signal hyperintensity on diffusion - weighted imaging and fat - suppressed t1 - weighting imaging , and no enhancement with contrast - enhanced mri . mri also revealed extended endometrium and multiple large tumors within the uterine body , comprising solid tumors regarded as typical leiomyoma , cystic tumors , and markedly degenerated tumors with cystic and edematous changes showing heterogeneously high signal intensity on t1 - and t2 - weighted imaging . these uterine tumors were poorly enhanced after injection of gadolinium chelate ( fig . 2 ) . mri also showed a right ovarian cystic tumor without solid part , measuring 6 cm , containing fluid showing signal hyperintensity on t1 - weighted imaging , signal hypointensity on t2 - weighted imaging , and poor enhancement . computed tomography ( ct ) showed no findings suggestive of apparent lymph node involvement or metastatic disease . the patient underwent simple hysterectomy , bilateral salpingo - oophorectomy and resection of the umbilical tumor . the cut surface of the nodule within the subcutaneous tissue of the umbilicus was grayish - white with scattered hemorrhagic spots . intraoperative findings showed necrotic cystic tumor of the right ovary with 1080 torsion of the pedicle , and a smooth - surfaced , huge uterus with protrusions of variable - sized cystic tumors and firm solid tumors . the removed uterus weighed 9.6 kg , measuring 3525 cm . histological findings of the umbilical tumor showed a glandular arrangement lined by columnar cells surrounded by stroma of spindle cells , corresponding to endometrial tissue , with scattered intraglandular hemorrhage and marked proliferation of smooth muscle cells and fibroblasts ( fig . examination of the uterus showed variable - sized , well - circumscribed tumors with disorderly arrangement of the smooth muscle fascicles , different degrees of hydropic , cystic , and hyaline degeneration , and edematous changes , without any nuclear atypia or mitotic changes ( fig . the right ovarian tumor showed severely necrotic changes with hemorrhage , and contained bloody fluid . postoperative diagnosis was endometriosis of the umbilicus , uterine leiomyomas with hydropic and cystic degeneration , and right ovarian cyst with ischemic change . the prevalence is reportedly less than 5.5 % of all cases of endometriosis , and its occurrence has recently been increasing ( kyamidis et al . , cutaneous endometriosis appears in surgical scars such as from cesarean sections , laparoscopy , hysterectomy , or episiotomy , and the remaining 30 % appear spontaneously , most commonly on the umbilicus , followed by the inguinal region ( kyamidis et al . , 2011 ; agarwal and fong , 2008 ; dessy et al . , 2008 ) . the pathogenetic mechanisms of cutaneous endometriosis have been speculated to involve iatrogenic implantation or hematogenous or lymphogenous metastasis of endometrial tissue ( latcher , 1953 ; kyamidis et al . , 2011 ; agarwal and fong , 2008 ; dessy et al . , 2008 ) . agarwal and fong noted that spontaneous cutaneous endometriosis was associated with more severe pelvic disease than scar endometriosis ( agarwal and fong , 2008 ) . umbilical endometriosis presents as a rubbery or firm nodule , and the size varies from several millimeters to 6 cm . clinical symptoms typically include pain , bleeding , and swelling correlated with the menstrual cycle , but some patients are asymptomatic ( kyamidis et al . , 2011 ; agarwal and fong , 2008 ; dessy et al . , 2008 ) . the pathology is mostly associated with pelvic endometriosis , with complaints of dysmenorrhea , dyspareunia , or defecation pain ( kyamidis et al . , 2011 ) . umbilical endometriosis can be suspected based on the clinical presentation , but the diagnosis should be confirmed by histological examination . yu et al . described two cases and hartigan and holloway reported one case of umbilical endometriosis , with signal hypointensity on t1 - weighted imaging and signal hypo - or hyperintensity on t2 - weighted imaging with 2 - to 3 - mm signal - hyperintense foci on t1 - weighted imaging and fat - suppressed t1 - weighted imaging . areas of signal hyperintensity on t1 - and t2 - weighted imaging were consistent with subacute hemorrhage containing extracellular methemoglobin , and areas of signal hypointensity on t2 - weighted imaging were consistent with hemosiderin and fibrotic tissue ( kyamidis et al . , 2011 ; yu et al . the present case also showed findings on mri corresponding to histological findings of thickened fibrotic tissue containing scattered intraglandular hemorrhage . yu et al . noted that mri is helpful to delineate the size and locations of lesions and to exclude the possibility of intraabdominal extension . mri may be more useful in detecting pelvic endometriosis than differential diagnosis of the umbilical nodule . treatment using pharmacotherapies such as gonadotropin - releasing hormone agonist ( gnrha ) or contraceptive pill alone is considered insufficient , but the medication can be effective for the relief of symptoms derived from pelvic endometriosis ( kyamidis et al . , 2011 ; agarwal and fong , 2008 ) . however , malignant transformation has been reported in 0.31 % of cutaneous endometriosis , particularly in patients with longstanding or recurrent endometriosis . common histological subtypes include endometrioid carcinoma , clear cell carcinoma , adenosarcoma , and serous adenocarcinoma ( kyamidis et al . , 2011 ; agarwal and fong , 2008 ) . the present case was initially suspected to involve malignant uterine tumor and its umbilical metastasis , but the findings on ultrasonography and mri demonstrated a high likelihood of benign uterine tumor . as uterine leiomyomas enlarge , they can outgrow their blood supply , resulting in various types of degeneration , such as hyaline ( 60 % of cases ) , cystic ( about 4 % ) , myxoid , or red degeneration ( ueda et al . , 1999 ) . reports of leiomyoma with marked cystic degeneration have been relatively uncommon ( aydin et al . , 2013 ) . the present case was uncommon in that it exhibited umbilical endometriosis , an extremely enlarged uterus due to marked hydropic and cystic degeneration of the leiomyomas , and torsion of the pedicle of the right ovarian cyst that had caused sudden pain in the right lower abdomen . the patient in this case made no complaints of umbilical tumor , symptoms derived from endometriosis , or apparent evidence of intrapelvic endometriosis . nevertheless , umbilical tumors in women involve endometriosis in approximately 30 % of cases ( barrow , 1966 ) . physicians should take into consideration the possibility of umbilical endometriosis in the case of umbilical nodules , particularly among reproductive - age women .\noutput:\n" }, { "from": "agent", "value": "highlightswe present an unusual case of umbilical endometriosis and huge uterine leiomyomas with marked hydropic and cystic degeneration.although umbilical tumors are uncommon , the differential diagnosis should include umbilical endometriosis , particularly in reproductive - age women.umbilical endometriosis can be suspected from the clinical presentation , but the diagnosis should be confirmed with histological examination ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: it has been reported that in autopsy cases of prostate cancer patients , adrenal metastasis is observed in 17 - 20 % of the cases and pleural metastasis is observed in around 20 % of the cases . however , there are few reports on clinical cases , and the case described here is only the fourth case of adrenal metastasis and the second case of pleural metastasis . as far as we could determine based on an extensive literature search , there have been no reports of prostate cancer that developed simultaneous metastases in both the adrenal glands and the pleura , and we herein report this case with a few bibliographical considerations . he became aware of increased urinary frequency starting in 2004 but did not undergo any specific check - ups . in 2006 , a high psa level was observed and the patient was referred to our hospital for a check - up . at the check - up , a high psa level of 515 ng / ml was observed and a transrectal prostate needle biopsy was performed . the pathological finding was moderately differentiated prostate cancer with a gleason score of 7 ( 4 + 3 ) . although bone metastasis was observed , there was no lymph node metastasis or any distant metastasis . the patient was diagnosed with having clinical stage d prostate cancer , and a maximum androgen blockade ( mab therapy ) was started . the cancer became exacerbated 1 year after starting the mab therapy . in response to the exacerbated prostate cancer , we started a therapy involving the administration of 8 mg / kg body weight of dexamethasone and 55 mg / m of docetaxel every 3 weeks . after completing 8 courses , an enlargement of the bilateral adrenal tumorwas observed , and after completing 12 courses , a pleural tumor was discovered and the psa level was also increased . the patient was therefore diagnosed with having bilateral adrenal metastasis and pleural metastasis of prostate cancer through diagnostic imaging ( fig . although it has been reported that 17 - 20 % of all autopsy cases of prostate cancer patients have adrenal metastasis , this case is only the fourth known clinical case , following cases reported by navarro et al . long and husband reported that out of 398 cases of prostate cancer in which an abdominal ct was performed , adrenal metastasis was observed in only 1 case . although many cases of unilateral pulmonary metastasis have been reported , there has been only 1 case of pleural metastasis in japan , reported by takagi et al . . however , it is believed that cases of pulmonary metastasis include cases that also involve pleural metastasis , and that the actual number of cases of pleural metastasis is therefore higher than reported so far . so far , there have been no reports of multiple occurrences of prostate cancer in the adrenal glands and the pleura , thus making this case the first such case .\noutput:\n" }, { "from": "agent", "value": "our case was 65 years old . at check - up , a high psa level of 515 ng / ml was observed , the patient was diagnosed with having clinical stage d prostate cancer and a maximum androgen blockade ( mab therapy ) was started . in response to the exacerbated prostate cancer , we started a therapy involving the administration of 8 mg / kg body weight of dexamethasone and 55 mg / m2 of docetaxel every 3 weeks . after completing 8 courses , an enlargement of the bilateral adrenal tumor was observed , and after completing 12 courses , a pleural tumor was discovered and the psa level was also increased . the patient was therefore diagnosed with having bilateral adrenal metastasis and pleural metastasis of prostate cancer through diagnostic imaging . so far , there have been no reports of multiple occurrences of prostate cancer in the adrenal glands and the pleura , thus making this case the first such case ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: prior to np [ xl184 ] synthesis , the biodegradable copolymer plga 50:50 ( 17 kda ; 0.18 dlg ; lake shore biomaterials ) was modified to incorporate a peg moiety ( cooh - peg - nh2 ; 3.5 kda ; jenkem technology ) , which enhances both nanoparticle stability and circulation time . nanoparticles were synthesized with various xl184 ( 99.0 % purity ; selleck chemicals ) and peg - plga drug / polymer ratios ranging from 110 % ( w / w ) . of the tested ratios , the xl184 molar loading efficiency was maximal at a drug / polymer ( w / w ) ratio of 1 % ( supplemental figure 2 ) . in addition , a range of solvent : water ratios ( 1:21:10 ) were tested and the optimal ratio for np [ xl184 ] formation was 1:3 acetone : water . for the optimized synthesis protocol , xl184 was co - solubilized in 1 ml of acetone with plga - peg at a 1 % ( w / w ) drug to polymer concentration . nanoprecipitation was achieved by adding this mixture drop - wise using a 27 - gauge needle to 3 ml of h2o stirred magnetically at 400 rpm . the reaction mixture was then stirred uncovered for 6 h to allow acetone evaporation , passed through a 0.2 m filter and purified by ultrafiltration ( amicon - millipore ; 30 kda cut - off ) at 2500 rpm for 10 min with intermittent washing ( 4 cycles ; 4 ml phosphate - buffered saline per wash ) . the xl184plga nanoparticle loading efficiency was determined by optical absorption measurements following solvation of the nanoparticles in dimethyl sulfoxide , using the formula : 100 ( no . all np [ xl184 ] size and charge measurements were made by dynamic light scattering ( malvern , zetasizer nano zs ) . pmils co - encapsulating bpd ( verteporfin ; vwr international ) and np [ xl184 ] were prepared by modification of existing synthesis methods . the lipids ( dppc , dotap , cholesterol , and dspe - peg ; avanti polar lipids ) were each dissolved separately in chloroform , and then mixed together in a molar ratio of 2:0.2:1:0.2 ( dppc : dotap : cholesterol : dspe - peg ) with 100 nmoles of bpd . this lipid composition was selected based on the previously reported pharmacological success of similar compositions . inclusion of the cationic lipid , dotap , resulted in a zeta potential ( surface charge ) of + 3 mv . this slightly cationic surface charge promotes cellular uptake without significant cytotoxicity to maintain biocompatibility . to form thin lipid films containing bpd , chloroform was removed by roto - evaporation and by placing the sample under vacuum overnight . next , lipid film hydration was achieved by adding np [ xl184 ] ( 50 nmoles of xl184 ) in 1 ml of phosphate - buffered saline . to ensure adequate encapsulation of np [ xl184 ] , the thin film was subjected to 10 freeze - thaw cycles ( 6 min per cycle ) at 0c and 45c , below and above the highest transition temperature of the lipid mixture ( dppc ; tm = 41c ) . the resulting dispersion of multilamellar liposomes was extruded through a 200 - nm - diameter polycarbonate membrane using a mini - extruder system ( avanti polar lipids ) to form unilamellar liposomes . bpd and xl184 not loaded into the pmil were removed by dialysis ( spectra / por ; 300 kda cut - off ; 1 ml sample in 4 l of phosphate - buffered saline at 4c for 18 h ) . during the dialysis periodinitially , these measurements indicated a bimodal distribution with peaks at 80 nm ( np [ xl184 ] ) and 150 nm ( pmil ) , which gradually became a single monodispersive peak ( pdi 0.2 ) as purification of the pmils completed . however , electron microscopy revealed the presence of residual np [ xl184 ] not incorporated within liposomes within the pmil samples ( supplementary note 3 ) . the pmil bpd and xl184 concentrations and loading efficiencies were determined by fluorescence and absorbance spectroscopy or by high - performance liquid chromatography ( hydrosil c18 ods ; 2.0 cm 14.0 cm ; 50 % acetonitrile in h2o 100 % acetonitrile ; 0.5 h ) , respectively , following solvation of the pmils in dimethyl sulfoxide . all pmil size and charge measurementspmil and np [ xl184 ] size stability during storage at 4c was investigated by repeated dynamic light scattering measurements over a period of 40 d ( supplementary fig . dark release and photoinduced drug release were measured using dialysis membranes in phosphate - buffered saline at 37c with 10 % fetal bovine serum added to each dialysis tube ( spectra / por ; np [ xl184 ] , 100 kda cut - off ; pmils , 300 kda cutoff ; fig .2 f ) . a 690 nm diode laser ( high power devices , inc . ) was used for all nir irradiation experiments . during dialysis sampleswere collected periodically and placed immediately in acetonitrile containing 1 % of the internal standard n - ( 1 - naphthyl ) ethylenediamine . separation and quantification of drug components was achieved by liquid chromatography - tandem mass spectrometry ( lc - ms / ms ) using standard curves for each drug normalized to the internal standard . briefly , 1.0 l of dialysis sample was injected into a zorbaxc18 ( 2.150 mm ) column eluted at 0.400 ml / min with acetonitrile and 10 mm ammonium formate ( 80 % 20 % over 4 min ) . detection of drug components was made using triple quadrupole ms / ms detection with an ion source esi + in mrm scan mode to identify the product ions for bpd ( ret . time = 2.68 min , 232 m / z ) . quantitative analysis of chromatograms allowed for area under curve integrations of each product ion normalized to the internal standard ( ret . total moles were determined using standard curves and percent loss calculated for each time point after correcting for sample volume changes . the resulting bpd and xl184 release profiles were fit individually to a simple one - or two - phase exponential model : a0 + a1 e + a2 e , where a0 is an offset , a1 and a2 are the maxima release plateaus ( at equilibrium ) of phases 1 and 2 , k1 and k2 are the release rate constants of phases 1 and 2 , and t is time from placing the sample in serum media within the dialysis tube . note that xl184 release from np [ xl184 ] is sufficiently described by a single - phase model ( p = 0.067 , two - phase alternative hypothesis ) , whereas xl184 release from the pmil with or without laser irradiation is best described by the multi - phase model ( p = 0.00030.0079 ) . dynamic light scattering and transmission electron microscopy were also performed before and after photoirradiation ( fig . 3 and supplementary fig . cryo - em was performed using a fei technai g2 polara microscope equipped with an energy filter ( gatan ) and a k2 summit direct detection device ( gatan ) . briefly , 5 l of nanomaterial sample ( ~ 60 m bpd for the pmil or l [ bpd ] ; ~ 30 or 125 m xl184 for the pmil or np [ xl184 ] , respectively ) mixed with 2 l of bsa gold tracer ( em - grade 6 nm ; electron microscopy sciences , 25484 ) re - suspended in phosphate - buffered saline were deposited onto glow - discharged holey carbon grids ( quantifoil r 2/1200 mesh , copper ; electron microscopy sciences ) , blotted and rapidly vitrified in a liquid ethane and propane mixture ( 50:50 ) using a custom - built plunger ( max planck institute of biochemistry , germany ) . kv under low - dose conditions with 4.98 or 6.12 sampling and a defocus of 3 or 6 m for 2d or 3d images , respectively .2 d images were obtained using the dose - fractionation mode of the detector ( ~ 2040 e / cumulative dose ) . tilt series ( 60 ) for tomography were collected around a single axis with a 2 sampling increment using serialem software ( ~ 100 e / cumulative dose ) . renders of 3d pmil and np [ xl184 ] objects were created by manual segmentation in imod and rendered using vmd .5 . only unambiguous np [ xl184 ] objects were counted ( ~ 20 nm in diameter or greater ) . mean lamellarity was calculated as : l ( nl l ) / lnl , where nl is the number of objects with lamellarity l ( e.g. , tem ( philips cm10 ) was performed using negative staining either on untreated ( 200 mesh nickel pelco support film with a formvar / carbon coating , ted pella inc . ) or ionized carbon coated grids ( to promote sample adhesion ) . briefly , 10 l of sample was added to the grid , air - dried and stained ( 2 l , 1.0 % phosphotungstic acid ) . imaging was performed at 100.0 kv and magnifications of ~ 10,00050,000 . monolayer cultures of aspc1 cells ( american type culture collection , crl - 1682 ; low passage number , 20 ) recently tested ( july 2015 ) and found to be negative for mycoplasma contamination ( mycoalert mycoplasma detection kit , lonza ) were maintained in media ( rpmi 1640 , mediatech ) supplemented with 10 % fetal bovine serum ( invitrogen ) , 100 units / ml penicillin and 100 g / ml streptomycin . the aspc1 cell line has not been listed in the database of cross - contaminated or misidentified cell lines maintained by the international cell line authentication committee . cellular uptake of pmils and l [ bpd ] was tested in multi - well plates with coverslip bottoms ( greiner bio - one ) plated with aspc1 cells allowed to attach and grow overnight . nanoconstructs were added to the wells at staggered time points to reach a concentration of 100 nm bpd and to achieve varying incubation times at 37c ( 1590 min ) . imaging was performed with an olympus fv1000 confocal microscope with a 200.75 na ( numerical aperture ) objective . bpd excitation was performed using a 405 nm diode laser with an emission spectrograph centred on the 696 nm bpd fluorescence emission peak . the laser , photomultiplier tube detector and pinhole settings , as well as brightness - contrast adjustment settings for display , were kept constant for all images . in addition , phase contrast images were collected during microscopy in order to focus on a high - density field of cells ( not shown ) . images were also collected for untreated cells ( 0 min ) to quantify the autofluorescence background and to define a fluorescence intensity threshold that rejects 99.5 % of the background signal . this intensity threshold was applied to all images to select pixels above the autofluorescence background ( true bpd signal ) for analysis . the resulting cellular uptake data was fit to a simple biexponential pharmacokinetic model : a ( e e ) , where k and j are the elimination and absorption rate constants , a is a coefficient dependent on the administered bpd dose as well as its bioavailability and t is time post - administration . for in vitro pdt , 0.2510 aspc1 cells were grown on a 35 - mm culture dish for 24 h and incubated with nanoconstructs containing bpd ( 250 nm equivalent ) and / or xl184 ( 100125 nm equivalent ) in 1 ml complete medium for 1 h. the incubation media was then replaced with 2 ml of fresh , complete media prior to photoirradiation . this removal of nanoconstructs not uptaken by cells prior to irradiation limits the release of xl184 and the generation of photocytotoxic species to intracellular and cell - associated nanoconstructs . singlet oxygen sensor green ( sosg ; molecular probes ) and d - mannitol ( sigma - aldrich ) were used to probe reactive oxygen species involvement in bpd - pdt - induce met activation . tyrphostin ag1478 ( sigma - aldrich ) and bacterial toxin b ( toxin b , clostridium difficile - calbiochem , millipore ) were used to test for involvement of enzymes known to participate in met transactivation . sosg and mannitol were added to cells immediately prior to laser irradiation in fresh media and then removed immediately after pdt by a second media replacement step . ag1478 and toxin b were incubated with cells in fresh media for 30 min and 2 h , respectively , prior to laser irradiation and then removed immediately after pdt by a second media replacement . all animal experiments were conducted with approval and according to guidelines established by the massachusetts general hospital institutional animal care and use committee . experiments were carried out on 6 - week - old male swiss nude mice weighing 2025 grams ( cox breeding laboratories ) . for tumour implantations and photoirradiation , tumours were implanted by injection of a 50 l volume containing 10 aspc1 cells in a 1:1 mixture of matrigel ( bd biosciences ) and culture media . subcutaneous tumours were implanted above the hind leg and tumour volumes were estimated longitudinally by measuring the three tumour dimensions using a calliper and the hemi - ellipsoid formula : volume = l w h / 6 , where l , w and h , are the tumour length , width and height . note that here , h , represents the measured height of the hemi - elliptical tumour , which is half the height of a full ellipsoid . eighteen days following cancer cell implantation , subcutaneous tumours reached volumes of ~ 50 mm prior to the start of treatment . for orthotopic tumour implantation , animals were laid supine , a small left abdominal flank incision was made to exteriorize the pancreas and the cell suspension was injected into the pancreas . a small amount of 10 % povidone / iodine was applied topically to the injection site . then the incision was closed with 4 - 0 sutures and 10 % povidone / iodine was then applied to the incision site to prevent infection . ten days after cancer cell implantation , orthotopic pancreatic tumours reached volumes of ~ 25 mm prior to the start of treatment . all injections for treatment were done intravenously ( tail vein ) in 200 l sterile phosphate - buffered saline . mice were randomized into the various treatment groups , and the tumours of mice receiving bpd were irradiated with nir light ( using the 690 nm diode laser listed above ) 1 h post - injection , delivered at an irradiance of 100 mwcm . subcutaneous tumours were irradiated transcutaneously while orthotopic tumours were surgically exposed as for tumour implantation and irradiated . fourteen days after treatment , orthotopic tumours were excised to estimate their volumes using callipers and the ellipsoid formula : volume = l w h / 6 . briefly , orthotopic pancreatic tumours were excised 2 weeks post - treatment , embedded in optimal cutting temperature compound and frozen at 80c . sections were ( 1 ) fixed in 1:1 acetone : methanol for 15 minutes at 20c , ( 2 ) air dried for 30 minutes , and ( 3 ) washed three times in phosphate - buffered saline . a blocking solution ( dako protein block reagent ) was applied for 30 minutes , followed by application of the immunostains , at ~ 5 g / ml monoclonal antibody ( mab ) each diluted in background reducing dako antibody diluent for 2 h at room temperature in a humidifying chamber . finally , the slides were washed again three times , mounted ( invitrogen slowfade gold with 4,6 - diamidino -2-phenylindole , dapi ) with a coverslip and sealed with nail polish . confocal fluorescence imaging was performed using an olympus fluoview 1000 confocal microscope with a 100.4 numerical aperture ( na ) or a 200.75 na objective . excitation of dapi , anti - mouse pecam - 1 ( cd31 ; clone 390 ; cbl1337 , millipore ) mab - alexa fluor 568 conjugates and anti - human cytokeratin 8 ( clone lp3k ; mab3156 , r & d systems ) mab - alexa fluor 647 conjugates was carried out using 405 - , 559 - and 635 - nm lasers , respectively . mosaic images of entire tumour cross - sections were collected and stitched together using the olympus fluoview software . the anti - human cytokeratin 8 stain ( a cytoskeletal protein highly expressed by aspc1 cells ) has dual selectivity for the epithelial cancer cells because it does not react with mouse proteins . all analyses were performed using custom matlab ( mathworks ) routines for batch image processing . microvessel density values were calculated from whole tumour sections , within viable tumour tissue only , and averaged over slices from the entire tumour rather than a more complex hot spot identification and calculation , which is difficult to define objectively . intratumoural microvessel volume is calculated by multiplying microvessel density with the viable tumour volume in each slice and then summing over the whole tumour by interpolation . here , we used the minimum tumour subsampling necessary based on a mathematical model to resolve a statistically significant change in intratumoural microvessel volume , as validated previously using the orthotopic aspc1 tumour model ( supplementary note 9 ) . a quantitative reverse transcription polymerase chain reaction ( qrt - pcr ) assay was performed on excised liver and iliac lymph nodes to estimate the number of human cancer cells in excised organs as described and validated previously . briefly , qrt - pcr is used to measure the total number of human cancer cells from the level of human and mouse glyceraldehyde 3 - phosphate dehydrogenase ( gapdh ) housekeeping genes . at least 300 mg of freshly excised liver and retroperitoneal lymph nodes were collected at the treatment endpoint and snap frozen in liquid nitrogen . the frozen samples were then pulverized and homogenized , followed by rna extraction ( rnaeasy plus mini kit ; qiagen ) . human and mouse gapdh gene were measured using custom synthesized primers ( invitrogen ) . for each specimen , the cycle threshold ( ct ) from human gapdh gene was normalized by ct from mouse gapdh gene . the normalized ct was quantified into number of cancer cells using a standard curve generated with a set of organ lysates from no - tumour control mice mixed with different numbers of human cancer cells . specific statistical tests are indicated in the figure captions and were carried out using graphpad prism ( graphpad software ) . parametric tests ( one - way anova with tukey s post - test ) were used for in vitro drug release ( fig .6 ) studies ; and , the dagostino & pearson omnibus normality test ( = 0.05 ; requires n 8 replicates per group ) did not identify significant deviations from normality within these data sets ( testing could only performed for groups with n 8 replicates ) . note that all groups within the drug release data were analysed together ( some groups appear only in supplementary fig .1 ) were analysed using nonparametric tests ( the mann - whitney u test or kruskalthe brown forsythe test ( = 0.05 ) was applied to all data sets with n 3 replicates to test for equal variance ( regardless of whether parametric or nonparametric analysis was used ) and identified significant deviations from equal variance ( figs . in these cases , the data were analysed following a logarithmic transform of the data to pass the brown forsythe test .5 d ) following a natural logarithm transform of the data to pass the dagostino & pearson omnibus normality test . no exclusion criteria were used , and no data points or animals were excluded from analysis . animal sample sizes were selected to ensure adequate power ( 80 % ) to detect a 20 % difference using a maximum of 16 animals per group assuming a standard deviation of 15 % . prior to np [ xl184 ] synthesis , the biodegradable copolymer plga 50:50 ( 17 kda ; 0.18 dlg ; lake shore biomaterials ) was modified to incorporate a peg moiety ( cooh - peg - nh2 ; 3.5 kda ; jenkem technology ) , which enhances both nanoparticle stability and circulation time . nanoparticles were synthesized with various xl184 ( 99.0 % purity ; selleck chemicals ) and peg - plga drug / polymer ratios ranging from 110 % ( w / w ) . of the tested ratios , the xl184 molar loading efficiency was maximal at a drug / polymer ( w / w ) ratio of 1 % ( supplemental figure 2 ) . in addition , a range of solvent : water ratios ( 1:21:10 ) were tested and the optimal ratio for np [ xl184 ] formation was 1:3 acetone : water . for the optimized synthesis protocol , xl184 was co - solubilized in 1 ml of acetone with plga - peg at a 1 % ( w / w ) drug to polymer concentration . nanoprecipitation was achieved by adding this mixture drop - wise using a 27 - gauge needle to 3 ml of h2o stirred magnetically at 400 rpm . the reaction mixture was then stirred uncovered for 6 h to allow acetone evaporation , passed through a 0.2 m filter and purified by ultrafiltration ( amicon - millipore ; 30 kda cut - off ) at 2500 rpm for 10 min with intermittent washing ( 4 cycles ; 4 ml phosphate - buffered saline per wash ) . the xl184plga nanoparticle loading efficiency was determined by optical absorption measurements following solvation of the nanoparticles in dimethyl sulfoxide , using the formula : 100 ( no . all np [ xl184 ] size and charge measurements were made by dynamic light scattering ( malvern , zetasizer nano zs ) . pmils co - encapsulating bpd ( verteporfin ; vwr international ) and np [ xl184 ] were prepared by modification of existing synthesis methods . the lipids ( dppc , dotap , cholesterol , and dspe - peg ; avanti polar lipids ) were each dissolved separately in chloroform , and then mixed together in a molar ratio of 2:0.2:1:0.2 ( dppc : dotap : cholesterol : dspe - peg ) with 100 nmoles of bpd . this lipid composition was selected based on the previously reported pharmacological success of similar compositions . inclusion of the cationic lipid , dotap , resulted in a zeta potential ( surface charge ) of + 3 mv . this slightly cationic surface charge promotes cellular uptake without significant cytotoxicity to maintain biocompatibility . to form thin lipid films containing bpd , chloroform was removed by roto - evaporation and by placing the sample under vacuum overnight . next , lipid film hydration was achieved by adding np [ xl184 ] ( 50 nmoles of xl184 ) in 1 ml of phosphate - buffered saline . to ensure adequate encapsulation of np [ xl184 ] , the thin film was subjected to 10 freeze - thaw cycles ( 6 min per cycle ) at 0c and 45c , below and above the highest transition temperature of the lipid mixture ( dppc ; tm = 41c ) . the resulting dispersion of multilamellar liposomes was extruded through a 200 - nm - diameter polycarbonate membrane using a mini - extruder system ( avanti polar lipids ) to form unilamellar liposomes . bpd and xl184 not loaded into the pmil were removed by dialysis ( spectra / por ; 300 kda cut - off ; 1 ml sample in 4 l of phosphate - buffered saline at 4c for 18 h ) . during the dialysis periodinitially , these measurements indicated a bimodal distribution with peaks at 80 nm ( np [ xl184 ] ) and 150 nm ( pmil ) , which gradually became a single monodispersive peak ( pdi 0.2 ) as purification of the pmils completed . however , electron microscopy revealed the presence of residual np [ xl184 ] not incorporated within liposomes within the pmil samples ( supplementary note 3 ) . the pmil bpd and xl184 concentrations and loading efficiencies were determined by fluorescence and absorbance spectroscopy or by high - performance liquid chromatography ( hydrosil c18 ods ; 2.0 cm 14.0 cm ; 50 % acetonitrile in h2o 100 % acetonitrile ; 0.5 h ) , respectively , following solvation of the pmils in dimethyl sulfoxide . all pmil size and charge measurementspmil and np [ xl184 ] size stability during storage at 4c was investigated by repeated dynamic light scattering measurements over a period of 40 d ( supplementary fig . release and photoinduced drug release were measured using dialysis membranes in phosphate - buffered saline at 37c with 10 % fetal bovine serum added to each dialysis tube ( spectra / por ; np [ xl184 ] , 100 kda cut - off ; pmils , 300 kda cutoff ; fig .2 f ) . a 690 nm diode laser ( high power devices , inc . ) was used for all nir irradiation experiments . during dialysis sampleswere collected periodically and placed immediately in acetonitrile containing 1 % of the internal standard n - ( 1 - naphthyl ) ethylenediamine . separation and quantification of drug components was achieved by liquid chromatography - tandem mass spectrometry ( lc - ms / ms ) using standard curves for each drug normalized to the internal standard . briefly , 1.0 l of dialysis sample was injected into a zorbaxc18 ( 2.150 mm ) column eluted at 0.400 ml / min with acetonitrile and 10 mm ammonium formate ( 80 % 20 % over 4 min ) . detection of drug components was made using triple quadrupole ms / ms detection with an ion source esi + in mrm scan mode to identify the product ions for bpd ( ret . time = 2.68 min , 232 m / z ) . quantitative analysis of chromatograms allowed for area under curve integrations of each product ion normalized to the internal standard ( ret . total moles were determined using standard curves and percent loss calculated for each time point after correcting for sample volume changes . the resulting bpd and xl184 release profiles were fit individually to a simple one - or two - phase exponential model : a0 + a1 e + a2 e , where a0 is an offset , a1 and a2 are the maxima release plateaus ( at equilibrium ) of phases 1 and 2 , k1 and k2 are the release rate constants of phases 1 and 2 , and t is time from placing the sample in serum media within the dialysis tube . note that xl184 release from np [ xl184 ] is sufficiently described by a single - phase model ( p = 0.067 , two - phase alternative hypothesis ) , whereas xl184 release from the pmil with or without laser irradiation is best described by the multi - phase model ( p = 0.00030.0079 ) . dynamic light scattering and transmission electron microscopy were also performed before and after photoirradiation ( fig . 3 and supplementary fig . cryo - em was performed using a fei technai g2 polara microscope equipped with an energy filter ( gatan ) and a k2 summit direct detection device ( gatan ) . briefly , 5 l of nanomaterial sample ( ~ 60 m bpd for the pmil or l [ bpd ] ; ~ 30 or 125 m xl184 for the pmil or np [ xl184 ] , respectively ) mixed with 2 l of bsa gold tracer ( em - grade 6 nm ; electron microscopy sciences , 25484 ) re - suspended in phosphate - buffered saline were deposited onto glow - discharged holey carbon grids ( quantifoil r 2/1200 mesh , copper ; electron microscopy sciences ) , blotted and rapidly vitrified in a liquid ethane and propane mixture ( 50:50 ) using a custom - built plunger ( max planck institute of biochemistry , germany ) . imaging was performed at 300 kv under low - dose conditions with 4.98 or 6.12 sampling and a defocus of 3 or 6 m for 2d or 3d images , respectively .2 d images were obtained using the dose - fractionation mode of the detector ( ~ 2040 e / cumulative dose ) . tilt series ( 60 ) for tomography were collected around a single axis with a 2 sampling increment using serialem software ( ~ 100 e / cumulative dose ) . renders of 3d pmil and np [ xl184 ] objects were created by manual segmentation in imod and rendered using vmd .5 . only unambiguous np [ xl184 ] objects were counted ( ~ 20 nm in diameter or greater ) . mean lamellarity was calculated as : l ( nl l ) / lnl , where nl is the number of objects with lamellarity l ( e.g. , l = 1 for unilamellar liposomes ) . tem ( philips cm10 ) was performed using negative staining either on untreated ( 200 mesh nickel pelco support film with a formvar / carbon coating , ted pella inc . ) or ionized carbon coated grids ( to promote sample adhesion ) . briefly , 10 l of sample was added to the grid , air - dried and stained ( 2 l , 1.0 % phosphotungstic acid ) . monolayer cultures of aspc1 cells ( american type culture collection , crl - 1682 ; low passage number , 20 ) recently tested ( july 2015 ) and found to be negative for mycoplasma contamination ( mycoalert mycoplasma detection kit , lonza ) were maintained in media ( rpmi 1640 , mediatech ) supplemented with 10 % fetal bovine serum ( invitrogen ) , 100 units / ml penicillin and 100 g / ml streptomycin . the aspc1 cell line has not been listed in the database of cross - contaminated or misidentified cell lines maintained by the international cell line authentication committee . cellular uptake of pmils and l [ bpd ] was tested in multi - well plates with coverslip bottoms ( greiner bio - one ) plated with aspc1 cells allowed to attach and grow overnight . nanoconstructs were added to the wells at staggered time points to reach a concentration of 100 nm bpd and to achieve varying incubation times at 37c ( 1590 min ) . imaging was performed with an olympus fv1000 confocal microscope with a 200.75 na ( numerical aperture ) objective . bpd excitation was performed using a 405 nm diode laser with an emission spectrograph centred on the 696 nm bpd fluorescence emission peak . the laser , photomultiplier tube detector and pinhole settings , as well as brightness - contrast adjustment settings for display , were kept constant for all images . in addition , phase contrast images were collected during microscopy in order to focus on a high - density field of cells ( not shown ) . images were also collected for untreated cells ( 0 min ) to quantify the autofluorescence background and to define a fluorescence intensity threshold that rejects 99.5 % of the background signal . this intensity threshold was applied to all images to select pixels above the autofluorescence background ( true bpd signal ) for analysis . the resulting cellular uptake data was fit to a simple biexponential pharmacokinetic model : a ( e e ) , where k and j are the elimination and absorption rate constants , a is a coefficient dependent on the administered bpd dose as well as its bioavailability and t is time post - administration . for in vitro pdt , 0.2510 aspc1 cells were grown on a 35 - mm culture dish for 24 h and incubated with nanoconstructs containing bpd ( 250 nm equivalent ) and / or xl184 ( 100125 nm equivalent ) in 1 ml complete medium for 1 h. the incubation media was then replaced with 2 ml of fresh , complete media prior to photoirradiation . this removal of nanoconstructs not uptaken by cells prior to irradiation limits the release of xl184 and the generation of photocytotoxic species to intracellular and cell - associated nanoconstructs . singlet oxygen sensor green ( sosg ; molecular probes ) and d - mannitol ( sigma - aldrich ) were used to probe reactive oxygen species involvement in bpd - pdt - induce met activation . tyrphostin ag1478 ( sigma - aldrich ) and bacterial toxin b ( toxin b , clostridium difficile - calbiochem , millipore ) were used to test for involvement of enzymes known to participate in met transactivation . sosg and mannitol were added to cells immediately prior to laser irradiation in fresh media and then removed immediately after pdt by a second media replacement step . ag1478 and toxin b were incubated with cells in fresh media for 30 min and 2 h , respectively , prior to laser irradiation and then removed immediately after pdt by a second media replacement . all animal experiments were conducted with approval and according to guidelines established by the massachusetts general hospital institutional animal care and use committee . experiments were carried out on 6 - week - old male swiss nude mice weighing 2025 grams ( cox breeding laboratories ) . for tumour implantations and photoirradiation , tumours were implanted by injection of a 50 l volume containing 10 aspc1 cells in a 1:1 mixture of matrigel ( bd biosciences ) and culture media . subcutaneous tumours were implanted above the hind leg and tumour volumes were estimated longitudinally by measuring the three tumour dimensions using a calliper and the hemi - ellipsoid formula : volume = l w h / 6 , where l , w and h , are the tumour length , width and height . note that here , h , represents the measured height of the hemi - elliptical tumour , which is half the height of a full ellipsoid . eighteen days following cancer cell implantation , subcutaneous tumours reached volumes of ~ 50 mm prior to the start of treatment . for orthotopic tumour implantation , animals were laid supine , a small left abdominal flank incision was made to exteriorize the pancreas and the cell suspension was injected into the pancreas . a small amount of 10 % povidone / iodine was applied topically to the injection site . then the incision was closed with 4 - 0 sutures and 10 % povidone / iodine was then applied to the incision site to prevent infection . ten days after cancer cell implantation , orthotopic pancreatic tumours reached volumes of ~ 25 mm prior to the start of treatment . all injections for treatment were done intravenously ( tail vein ) in 200 l sterile phosphate - buffered saline . mice were randomized into the various treatment groups , and the tumours of mice receiving bpd were irradiated with nir light ( using the 690 nm diode laser listed above ) 1 h post - injection , delivered at an irradiance of 100 mwcm . subcutaneous tumours were irradiated transcutaneously while orthotopic tumours were surgically exposed as for tumour implantation and irradiated . fourteen days after treatment , orthotopic tumours were excised to estimate their volumes using callipers and the ellipsoid formula : volume = l w h / 6 . briefly , orthotopic pancreatic tumours were excised 2 weeks post - treatment , embedded in optimal cutting temperature compound and frozen at 80c . sections were ( 1 ) fixed in 1:1 acetone : methanol for 15 minutes at 20c , ( 2 ) air dried for 30 minutes , and ( 3 ) washed three times in phosphate - buffered saline . a blocking solution ( dako protein block reagent ) was applied for 30 minutes , followed by application of the immunostains , at ~ 5 g / ml monoclonal antibody ( mab ) each diluted in background reducing dako antibody diluent for 2 h at room temperature in a humidifying chamber . finally , the slides were washed again three times , mounted ( invitrogen slowfade gold with 4,6 - diamidino -2-phenylindole , dapi ) with a coverslip and sealed with nail polish . confocal fluorescence imaging was performed using an olympus fluoview 1000 confocal microscope with a 100.4 numerical aperture ( na ) or a 200.75 na objective . excitation of dapi , anti - mouse pecam - 1 ( cd31 ; clone 390 ; cbl1337 , millipore ) mab - alexa fluor 568 conjugates and anti - human cytokeratin 8 ( clone lp3k ; mab3156 , r & d systems ) mab - alexa fluor 647 conjugates was carried out using 405 - , 559 - and 635 - nm lasers , respectively . mosaic images of entire tumour cross - sections were collected and stitched together using the olympus fluoview software . the anti - human cytokeratin 8 stain ( a cytoskeletal protein highly expressed by aspc1 cells ) has dual selectivity for the epithelial cancer cells because it does not react with mouse proteins . all analyses were performed using custom matlab ( mathworks ) routines for batch image processing . microvessel density values were calculated from whole tumour sections , within viable tumour tissue only , and averaged over slices from the entire tumour rather than a more complex hot spot identification and calculation , which is difficult to define objectively . intratumoural microvessel volume is calculated by multiplying microvessel density with the viable tumour volume in each slice and then summing over the whole tumour by interpolation . here , we used the minimum tumour subsampling necessary based on a mathematical model to resolve a statistically significant change in intratumoural microvessel volume , as validated previously using the orthotopic aspc1 tumour model ( supplementary note 9 ) . a quantitative reverse transcription polymerase chain reaction ( qrt - pcr ) assay was performed on excised liver and iliac lymph nodes to estimate the number of human cancer cells in excised organs as described and validated previously . briefly , qrt - pcr is used to measure the total number of human cancer cells from the level of human and mouse glyceraldehyde 3 - phosphate dehydrogenase ( gapdh ) housekeeping genes . at least 300 mg of freshly excised liver and retroperitoneal lymph nodes were collected at the treatment endpoint and snap frozen in liquid nitrogen . the frozen samples were then pulverized and homogenized , followed by rna extraction ( rnaeasy plus mini kit ; qiagen ) . human and mouse gapdh gene were measured using custom synthesized primers ( invitrogen ) . for each specimen , the cycle threshold ( ct ) from human gapdh gene was normalized by ct from mouse gapdh gene . the normalized ct was quantified into number of cancer cells using a standard curve generated with a set of organ lysates from no - tumour control mice mixed with different numbers of human cancer cells . specific statistical tests are indicated in the figure captions and were carried out using graphpad prism ( graphpad software ) . all reported p values are two - tailed . parametric tests ( one - way anova with tukey s post - test ) were used for in vitro drug release ( fig .6 ) studies ; and , the dagostino & pearson omnibus normality test ( = 0.05 ; requires n 8 replicates per group ) did not identify significant deviations from normality within these data sets ( testing could only performed for groups with n 8 replicates ) . note that all groups within the drug release data were analysed together ( some groups appear only in supplementary fig .1 ) were analysed using nonparametric tests ( the mann - whitney u test or kruskalwallis one - way anova ) . the brown forsythe test ( = 0.05 ) was applied to all data sets with n 3 replicates to test for equal variance ( regardless of whether parametric or nonparametric analysis was used ) and identified significant deviations from equal variance ( figs . in these cases , the data were analysed following a logarithmic transform of the data to pass the brown forsythe test .5 d ) following a natural logarithm transform of the data to pass the dagostino & pearson omnibus normality test . no exclusion criteria were used , and no data points or animals were excluded from analysis . animal sample sizes were selected to ensure adequate power ( 80 % ) to detect a 20 % difference using a maximum of 16 animals per group assuming a standard deviation of 15 % . for the subcutaneous model , significance\noutput:\n" }, { "from": "agent", "value": "nanoscale drug delivery vehicles can facilitate multimodal therapies of cancer by promoting tumour - selective drug release . however , few are effective because cancer cells develop ways to resist and evade treatment . here , we introduce a photoactivatable multi - inhibitor nanoliposome ( pmil ) that imparts light - induced cytotoxicity in synchrony with photo - initiated and sustained release of inhibitors that suppress tumour regrowth and treatment escape signalling pathways . the pmil consists of a nanoliposome doped with a photoactivatable chromophore ( benzoporphyrin derivative , bpd ) in the lipid bilayer , and a nanoparticle containing cabozantinib ( xl184 ) a multikinase inhibitor encapsulated inside . near infrared tumour irradiation , following intravenous pmil administration , triggers photodynamic damage of tumour cells and microvessels , and simultaneously initiates release of xl184 inside the tumour . a single pmil treatment achieves prolonged tumour reduction in two mouse models and suppresses metastatic escape in an orthotopic pancreatic tumour model . the pmil offers new prospects for cancer therapy by enabling spatiotemporal control of drug release whilst reducing systemic drug exposure and associated toxicities ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the dutch practice of physician - assisted dying ( pad ) has reached a phase of integration since the early eighties of the previous century , when the royal dutch society for the advancement of medicine ( rdsm ) came out in favor of the possibility of pad in 1984 . before that date , since the seventies , a growing acceptance of this practice appeared in various court cases of physicians being accused of criminally ending the life of a patient . before 1998 , each case of pad led to a criminal investigation by the police and ultimately was decided at a central level in the justice department , with a final decision by the secretary of justice . five cases on pad have been decided by the highest legal institution , the hoge raad , meaning high council , leading to a further refinement in detail of the legal norms under which physicians could end the life of a patient without running the risk of criminal proceedings . all of these cases except for one ended with light and often suspended sentences for technicalities or to a verdict of not guilty . the exception , the last case , in 2004 , concerned a verdict of a lower court that was upheld , because the patient in question , even though she suffered unbearably according to the physician and family , never had expressed a request to die . the important fact to remember is that the focus in these court cases never has been the ending of life as a criminal act , as murder . instead , the focus has been on the nature of medical participation at the end of life , with severely ill patients or patients with a terminal disease . from a normative anglethe courts orientation has been on medical science and medical practice : how physicians deal with sick patients at the end of their life and how they assist patients according to medical protocol and custom ( pans 2006 ) . the developments in the netherlands culminated in the acceptance of a law , effective since april 1 , 2002 , named : review procedures for the termination of life on request and assisted suicide and amendment of the criminal code and the burial and cremation act . the law is a codification of previous jurisprudence , with one addition : the option of an advance directive with a request to end life in case of legal incompetence . the basis of this law , often called the euthanasia law , is a distinction between interventions at the end of life that are called normal medicine and those that are called not normal medicine . death in the course of a non - treatment decision , in the course of the alleviation of pain and suffering , including palliative sedation in case of refractory symptoms , are considered normal medicine , resulting in a natural death . euthanasia , physician - assisted suicide and ending of life without a request ( with acronym lawer ) are considered not normal medicine . contrary to a general misconception , believing that pad islegalized in the netherlands , it should be stressed that these interventions are still considered crimes . the subtle distinction of the euthanasia law is that each case of active help in dying may still be a crime , unless the intervention is carried out by a physician who has to report the act and will be evaluated on the basis of the conditions of the law . with the exception of the lawer group : in the case of absence of a request criminal procedures will follow .1 the law also makes the previous central position of the criminal prosecution somewhat peripheral . since 2002 , the euthanasia review committees ( ercs ) have the final say in matters of pad : they decide whether a case has been carried out withthe case is referred to the criminal prosecution and the medical inspectorate , a kind ofmedical police . the euthanasia law is by its nature physician - centered : in it the conditions are described under which a physician who reports his act will not be prosecuted . these conditions are that a physician : must be convinced that it concerns a voluntary and well considered requestmust be convinced that it concerns unbearable and hopeless suffering of a patienthas informed the patient about the medical condition and the optionshas concluded with the patient that there are no reasonable alternatives for the situation of the patienthas consulted with at least one other physician independent of the case , who has seen the patient and has given his conclusions in writing with respect to the above conditions andhas carried out the life ending intervention or assisted suicide in a medically correct way must be convinced that it concerns a voluntary and well considered request must be convinced that it concerns unbearable and hopeless suffering of a patient has informed the patient about the medical condition and the options has concluded with the patient that there are no reasonable alternatives for the situation of the patient has consulted with at least one other physician independent of the case , who has seen the patient and has given his conclusions in writing with respect to the above conditions and has carried out the life ending intervention or assisted suicide in a medically correct way the life ending intervention must be reported to a local medical officer and extensive forms and medical reports for evaluation must be made available for the erc s . it has had the audacity or expediency , depending on how one chooses to qualify this choice , to organize costly national research programs to find out how dutch people die , in what ways , where and by what measures and to evaluate the legal and medical professional rules and regulations . about every 5 years since 1990these programs are carried out and allow broad reflection on the quality of care at the end of life ( 1990 , 1995 , 2001 , 2005 ) . they also serve as checkpoints for undesirable developments such as ( the fear of ) a slippery slope for pad . so far , this fear has proven not to be realistic , based on research over these 15 years ( van alphen et al . in the mean time , between 1990 and 1997 , much attention has been paid to develop and institutionalize measures to safeguard against undesirable practices . consultations by independent medical doctors , being unfamiliar with and not involved in the case , take place before pad , evaluations by the ercs afterwards . medical consultation before the act as opposed to a judicial one , because of the necessity for a consultation within a time frame of days rather than weeks . andin the second place , it was considered to be contradictory to involve the law in checking whether an intervention that in principle had not taken place and was criminal in nature , should be given the green light . from 1997 on , the rdsm , with broad financial support of the government , has established courses for potential professional consultants to physicians who have decided to honor a request to help to die . nowadays , there are professional consultants in all regions of the rdms , numbering more than 600 individuals . they are experienced physicians , most of them are family physicians , reflecting the high interest of this group in pad from early on , and about 15 % are hospital based clinicians and nursing home physicians , the latter a medical specialty in the netherlands . from 1998 on , there are also five euthanasia review committees ( ercs ) , reflecting the number of judicial regions in the netherlands . these are multidisciplinary committees , with three members : a lawyer , a physician and an ethicist , with nominated deputies for each discipline . these committees meet on a monthly basis to evaluate each case of pad that has been reported , and they must evaluate and report back within a time period of 6 weeks . the delegation of the evaluation afterwards to athe idea behind it was to increase the rate of reporting by including a physician , even though there was hesitancy to delegate the evaluation of a serious potential crime to others than the normal legal institution for prosecution . the idea was to put the criminal law at some distance , leaving the possibility of criminal procedures in principle open . they publish annual reports to render account of their activities and to fulfill one of the basic requirements behind all dutch regulations concerning euthanasia ( e ) and physician - assisted suicide ( pas ) , to make the practice transparent and to take pad out of agrey area , without the veil of previous ignorance that still persists in medicine other than the netherlands , belgium and oregon . this veil of ignorance does not imply in any way a low level of public discourse : on the contrary . but nowhere has a country other than the netherlands made a scientifically valid investigation concerning an overall view of the ways in which people die , in order to discover the extent of legal or illegal practices . in their annual reportsthe ercs describe cases that were found to be problematic or without due care , mostly on technical grounds , but also , and more interesting , cases where they focus on the absolute nature of the limits of possibilities for e and pas under the law . this focus is by definition on individual cases , weighing the individual facts of a case and finding out if these specific facts lead to conclusion of a careful procedure , or not . these decisions have a certain guiding meaning and function as precedents in the decisions of these multidisciplinary committees . precedents is formulating answers to individual cases with a complexity that is answered on an individual basis , but also establishing validity in conformity of the law in other comparable cases . corrective decisions concern for example issues of adequate consultations , sometimes not independent enough or the question of ( the absence of ) a well defined treatment relationship of the physician who carries out the final intervention , or the use of pharmaceutical substances other than the officially prescribed ones . acceptable euthanasia can be observed in cases where patients lose full consciousness in the end and yet the life ending takes place , because there is no uncertainty or hesitance about the nature of unbearable suffering or the desire of the patient . another example , one that is certain to cause much reaction , concerns the acceptance of pad in cases of early alzheimers , where after unusually long drawn out procedures the request of a patient has been accepted as coming from a competent person , while the unbearable nature of the suffering is also established without doubt for the involved physicians .2 over all these years , from 1998 through 2008 , 38 cases have been deemed to be without due care . testifying to the scrutiny of the committees and their rather rigid evaluations is the fact that in none of these cases the legal authorities have seen adequate ground for criminal proceedings . the present conservative government has opted to maintain the existing procedures and resist any attempt to extend e and / or pas to other groups of patients or to elderly without a disease but with a request to end life , the so - called people who suffer from life , having lost the desire to live on . only in countries where a practice of euthanasia and / or pas is allowed , is open and transparent research with a claim of validity is possible . in the past and current debates on euthanasiaone type of argument focuses on the negative effects of such a practice on families , care givers and society , the so - called consequentialist arguments , with a focus on the negative effects for patients , families and physicians . in the first pilot study on the effects of pad on families in 1990 , carlucci - ciesielski and i discovered in families we interviewed an extremely positive feeling about the active end of life of a family member ( ciesielski and kimsma 1994 ) . , the mother excluded the young children from the process of decisions leading up to the intervention . silence , but the spouse felt that this secret in the family made the acceptance of this death more difficult . this example did not constitute an argument against the euthanasia in itself , but was more of an argument against a lack of transparency and openness in the various steps .3 the small number of the families we interviewed in the pilot project was not representative and made it difficult to generalize the conclusions of an overall very satisfying intervention , with grief but also feelings of being content that further suffering had been spared . in a larger retrospective project swarte et al . ( 2003 , p. 189 ) compared grief in two groups of next of kin of women who died of a gynecological cancer in the period of 1992 through 1997 in the academic center of the utrecht university . the various instruments they used to assess the stages and intensity of grieving showed significantly less grief in the group of pad . even though the editors of bmj choose a caption readingbereaved people cope better after euthanasia than natural death , the authors are extremely careful and refrain from that conclusion . but they point out that e and pas make it possible to come to terms with the death of someone because of the possibility of anticipatory grief and an opportunity to discuss impending death freely and extensively in an open atmosphere with the patient that will die . there has also been research on the effects of pad on physicians , and to a lesser extent on what it means for other care givers such as nurses and families . the first pilot interviews were by thomasma , kushner and kimsma , in 1994 , published in asking to die . inside the dutch debate about euthanasia ( 1998 ) ( thomasma et al . 1998 ) . these interviews , with oncologists , family physicians and one nursing home physician , started with a leading question to speak about thethe range of emotions varied from extreme shock to anxieties , leading to sleeplessness and deep struggles to come to a final conclusion , but also deep satisfaction after the act . again , the small number of interviews could not lead to generally valid conclusions , but these did show up in the larger representative sample of personal interviews with 405 physicians , as part of the second national research into medical decisions at the end of life from 1995/1996 ( haverkate et al . 2001 , 519 ) . these and other interviews affirmed the emotional involvement after a request ( van marwijk et al . they showed the same range of emotions , but with some curious apparent contradictions . physicians showed both feelings of comfort afterwards and feelings of discomfort . however , physicians who participated in euthanasia , after a request and with an assessment of unbearable suffering , showed morenegative emotions in comparison with physicians who had ended the life of patient without a request , the group of so - called life ending without an explicit request ( lawer ) . the majority of this latter patient group suffered because of a serious incurable disease and were not able to communicate . so it appeared that following a procedure that formally is illegal , early on and still now , the emotional experiences were less problematic than acting within the procedural conditions of a law . but even though the physicians who had performed euthanasia seemed to suffer more , 95 % declared to be willing to perform that act in similar situations ; 5 % had doubts , but none had regrets . at that time the authors of the article were surprised at this difference in effects between theeuthanasia group and the lawer group , but these unexpected data were not a reason for deeper reflection : it is striking that ending a patient s life without an explicit request later evoked feelings of discomfort ( burdensome , emotional or a heavy responsibility ) less frequently than did performing euthanasia or assisted suicide . we believe that this difference between expectation and outcome calls for further analysis and explanation . we are convinced that this difference in emotional reaction towards a request for euthanasia is essential for understanding what a request means in medical and psychological terms . our thesis and conclusion is that deeper emotional reactions reflect a different relationship in cases of e and pas in comparison with the doctor - patient relationship of lawer , but also in comparison to normal care , even with patients with a terminal disease . physicians in the netherlands are confronted with requests to help to die on the average 2 or 3 times a year . there are about ten times more requests than actual cases , because many people ask these questions just to come to some assurance of this option in the future . requests for the near future from sick people are about 3 times more often than actual requests to be helped in a short while . reasons for physicians to refuse in two out of three cases are : the presence of alternative treatments , the level of suffering , the lack of depth in a request , an incorrect assessment of the seriousness of a disease by the patient , the unilateral withdrawal of a request or : objections in a particular case or in general against pad of a physician . each item in itself is a reason for further analysis . however , what these refusals have in common and what remains hidden in the sequential description of these reasons is the fact that each request starts a process of deliberation that has special qualities as compared to the interactions in the usual physician - patient relationship . that process of deliberation , the euthanasia discourse , has been the focus of research by american anthropologist frances norwood ( norwood 2009 ) . she observed and participated in the work of 10 family physicians in amsterdam , followed and interviewed their terminal patients . patient relationship lies in the commitment that a request implies : the possibility to have to end the life of a patient when suffering becomes unbearable and the patient persists in wishing to die . this commitment , with all respect , goes beyond the commitments of usual or normal care at the end of life . in fact , all aspects of usual care including palliative measures are implied , but there are additional aspects . being confronted with a request to end life creates conflicts for physicians and all others who are involved . ending life is an inherently immoral intervention , a crime in all societies . as buchanan statesforcefully : if anything is wrong , that is wrong ( buchanan 1996 ) . this conflict has at least two sources : a psychological and an ethical - philosophical source . the psychological conflict concerns a confrontation with mortality in a way that escapes the usual professional resistance to fears and anxieties when patients appear to have a terminal disease . patients and physicians both live in a culture of denial of death and medical technology is the instrument par excellence to realize that denial . but even though , according to freud , there can be a rational acceptance of death , the unconscious promotes behavior that clings to the idea of immortality ( freud 1957 ) . physicians have learned to counter emotions with professional distance and objectivity in order to be able to help patients accommodate to the realities of impending death . however , the appearance of fears , anxieties and sleeplessness after a request is testimony of the insufficiency of this professional self protection in this particular situation . stein describes these processes of care in terms of continuous transference and counter transference , interactions that are not limited to psychoanalysis only . caring implies a continuous identification with one s own motives as a care giver and the motives and desires of patients ( stein 1985 , p. 21 ) . this process is largely unconscious and a physician s attitude can be seen as a mix of personal anxieties for death , motives for becoming a physician , personal and professional experiences with death and dying and the ethos of modern medicine . caring for terminal patients often implies a closeness and high level of emotional involvement and compassion . however , patients requesting help in ending their life break these barriers to anxieties down and force physicians to identify with their patients suffering over the borders of their anxieties . in order to be able to help a patientdie they need to become convinced in a rational way that the authentic answer to that suffering is an active ending of life . this implies a need to come closer to the patient who has expressed that request . the necessity to come to a conclusion that the suffering of this particular patient indeed has become unbearable as a joint conclusion between physician and patient implies intimate knowledge of the patient as a person and a human being with a biographythis joint activity is keenly distinguished in the dutch euthanasia law where it is stipulated that physician and patient together have come to a conclusion that , for euthanasia to be allowed , there is no other reasonable solution available . suffering has many sides , but in essence two philosophical approaches can be distinguished : the empirical side of suffering and the hermeneutic side . unbearable suffering does not only concern the empirical , physical symptoms or complaints and the loss of functions and independence . essential for the evaluation is the hermeneutic aspect : what these symptoms and loss of functions mean to a patient as personal evaluations of that patient . in order to be able to perform that functiona physician must know about the patient as a person , the patient s biography and the patient s context and balance of endurance and tolerance . the second source of emotional conflicts for physicians who are confronted with a request to help someone die has philosophical and ethical roots . the principle objection against euthanasia is that ending a person s life goes against the grain of a fundamental prohibition : thou shallt not kill . in most civilized societies even the execution of killers is now prohibited , in conformity with this rule . in our culture , christianity has been forced to reflect intensely on the feasibility of the absolute nature of this principle . the absolute interpretation conflicted with the desire to become the religion of the state , after constantine the great s conversion to christianity in 325 ad . in order to become the religion of the state , the church had to accept the killing of enemy soldiers in aggression . this option , however , has never been open to individuals , even in case of self defense , according to saint augustine ( 354430 ) . thomas aquinas ended the dispute in the twelfth century with his definition that taking innocent life is immoral at all times ( rachels 1987 ) . based on these convictions , taking innocent life in medicine appears to be a paradigmatic example of a fundamentally immoral intervention , as many still feel today ( pellegrino et al . 1988 ) . nevertheless , throughout all time and ages , there has been a growing support among medical professionals and lay persons to allow the option to end the life of seriously ill people . there have been large euthanasia movements in the usa , great britain and germany since the middle of the nineteenth century . in the ethical dilemma between prohibition and acceptanceaccording to buchanan , principle arguments against the intervention are the denial of a person s well being and dignity and the violation of his right to life . however , in case of serious illness , the disease already has taken a patient s wellbeing and dignity . and secondly , a right to life implies the option not to exercise that right any longer . that choice is entirely the individual s choicethat is essentially the meaning of autonomy , and from this conclusion it follows that autonomy is the fundamental argument to justify the taking of life . this position is reflected in dutch jurisprudence and law : without a request there can not be a justified euthanasia or physician - assistance in suicide . however , autonomy is not the sole justification . a request by itself is insufficient justification : it would lead to a permissive system for which no physician has expressed support . this experience is not an individual s quality but the expression of a relation . to respond to unbearable suffering and breaking a fundamental law , being able to end the life of a patient implies the existence of a physician - patient relationship with different qualities than inthis reciprocity has been observed by consultants and discussed in interviews with physicians ( obstein et al . one of the signs of this mutuality is the fact that the final decision to go ahead with e or pas is taken after a process in which patient and physician come to a joint shared conclusion that suffering indeed has become unbearable and hopeless . it is the result of communication about medical options and how patients experience these options in the light of the progress of the disease , their vision about how much they choose to endure and the quality of life . there may be and often are differences of opinion in the possibilities of palliative measures . as norwood has shown , physicians tend to wait until patients initiate the next steps in the sequence of events leading to e and pas . patients sometimes need to wait until they have convinced their physician . they do so , out of respect . patients very well know that what they ask of a physician is the ultimate of what human beings can ask each other . recent research with patients who request for e or pas has shown a difference in focus on suffering between physicians and patients ( pasman et al . physicians tend to focus on physical symptoms such as pain and chronic fatigue , patients stated that the pain did not make their suffering unbearable , but seemed mainly to consist of non - physical suffering , such as ( fear of ) dependence , no longer being able to participate in normal daily life , or mental suffering , because of deterioration . physicians also would focus on what the authors describe ascoherence : a difference in expected and actual behavior of a patient , such as reading a book , or being able to open the front door in order to welcome the physician . during the process of euthanasiait is important to reflect on the issue whether a relationship of that type fits customary conceptions of the doctorclark and i reintroduced the notion of medical friendship to describe the different relationship in case of a euthanasia process ( clark and kimsma 2004 ) . we proposed aristotle s notions of friendship to qualify that type of relation ( aristotle 1999 , book eight ) . what aristotle describes in the nicomachean ethics is friendship based on either pleasure , utility or virtue . what is key for the physician and patient is the concept of reciprocal love or similar virtue that makes the category of virtue necessary for a complete friendship . one important aspect of this reciprocity is that no one who is a complete friend would ask the other to do something morally base and contrary to virtue . doing so would demonstrate that the relationship never was or is no longer founded on shared virtue ; it has become one of utility ( clark and kimsma 2004 , p. 64 ) . physician relationship is not alien to medicine : linda and ezekiel emanuel have proposed adeliberative model in which the physician acts as a teacher or friend , engaging the patient in dialogue on what course of action would be best ( emanuel and emanuel 1999 ) . their description gives maximum room for patient values , but it lacks space for the physician s values . what is essential to realize is that the patient must respect what is asked of the physician as much as the physician must come to terms with what the patient requests , in a process of mutuality with a final interpersonal agreement . my intention has been to show that a request for euthanasia or physician - assisted suicide has emotional effects on patients , families and physicians . the focus has been on physicians and patients with the aim to analyze why a request evokes such emotional responses . research attests to the depth of what it means for a physician to end the life of a patient . these deeper unsettling responses , however , are reasons for deeper relationships than in daily medicine with its focus on healing . they serve as conditions to be able to assess the unbearable suffering of patients and in the end to come to a joint conclusion that this suffering has been enough .\noutput:\n" }, { "from": "agent", "value": "in this article i intend to describe an issue of the dutch euthanasia practice that is not common knowledge . after some general introductory descriptions , by way of formulating a frame of reference , i shall describe the effects of this practice on patients , physicians and families , followed by a more philosophical reflection on the significance of these effects for the assessment of the authenticity of a request and the nature of unbearable suffering , two key concepts in the procedure towards euthanasia or physician - assisted suicide . this article does not focus on the arguments for or against euthanasia and the ethical justification of physician - assisted dying . these arguments have been described extensively in kimsma and van leeuwen ( asking to die . inside the dutch debate about euthanasia , kluwer academic publishers , dordrecht , 1998 ) ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: anterior cruciate ligament ( acl ) avulsion fracture is commonly associated with knee injuries and its management is controversial ranging from conservative treatment to arthroscopic fixation . the aim of our study was to assess the clinical and radiological results of arthroscopic staple fixation in the management of acl avulsion fractures . twenty - two patients ( 17 males and 5 females ) who underwent arthroscopic staple fixation for displaced acl avulsion fractures were analysed . the mean age was 32.2 years ( 15 - 55 years ) with a mean followup of 21 months ( 6 - 36 months ) . all patients were assessed clinically by calculating their lysholm and international knee documentation committee ( ikdc ) scores and the radiological union was assessed in the followup radiographs . the mean lysholm score was 95.4 ( 83 - 100 ) and the mean ikdc score was 91.1 ( 77 - 100 ) at the final followup . in 20 patientsanterior drawer 's test was negative at the end of final followup while two patients had grade i laxity . the final outcome was not greatly influenced by the presence of associated injuries when treated simultaneously . at final followuparthroscopic staple fixation is a safe and reliable method for producing clinical and radiological outcome in displaced acl avulsion fractures . anterior cruciate ligament ( acl ) avulsion fractures contribute most of the injuries around the knee joint and result in significant disability if left untreated . they are caused by forceful hyperextension of the knee or by a direct blow over distal end of femur with the knee flexed . in the past , non - operative method of treatment in the form of immobilization of the knee in full extension or in 20 of flexion1 the position in which acl is most relaxed was followed . reduction is not achieved by manipulating the knee into hyperextension with the patient anesthetized , which can neither dislodge nor approximate the fragment to its bed1 since the fractured fragment is not between the articulating surface of tibia and femur , but lies in an empty non - articulating area of the joint . open reduction and internal fixation of tibial spine fractures carries a risk of knee stiffness and infection .2 arthroscopic fixation of acl overcomes the complications of long - term immobilization , such as knee stiffness and dvt . the aim of our study was to evaluate the clinical and radiological results of acl avulsion fractures treated by arthroscopic staple fixation technique . twenty - two patients ( 17 males and 5 females ) who underwent arthroscopic staple fixation of displaced acl avulsion fractures from january 2007 to june 2009 and had completed the minimum followup of six months and were available for final assessment were included in our study . the mean age of the patients was 32.2 years ( range 15 to 55 years ) . the mode of injury was road traffic accident in 19 patients and secondary to twisting injury in 3 patients . all patients were assessed in the casualty by a careful physical examination to rule out associated injuries and by a plain radiograph of the knee joint [ figure 1 ] . thirteen patients had type ii injury of the acl ( anterior third displacement of the avulsed fragment ) and nine patients had type iii injury of the acl where the avulsed fragment was displaced completely . patients with associated ipsilateral knee injuries were included , whereas patients with polytrauma and contra - lateral limb injuries were excluded from the analysis . plain radiograph anteroposterior ( a ) and lateral view ( b ) of right knee of a 28 year old man with acl avulsion fracture four patients with severe communition of the avulsed fragment underwent mri of the knee to assess the size of the largest bony fragment attached to the acl that might allow fixation with a staple and also to assess the integrity of the acl fibers . the medial portal was higher than the lateral portal and in a more vertical position to facilitate the staple fixation [ figure 2 ] . sometimes an additional higher lateral portal was needed to fix the fragment from lateral side . thorough wash was given to drain the hematoma and the avulsed acl fragment was visualized [ figure 2b ] and it was made sure that there was no meniscal interposition . the titanium staple [ figure 2c ] is of 2 centimeters length and has two v - shaped fangs . it was threaded to the introducer and inserted through the high medial portal and placed over the avulsed fragment . the fragment was reduced to its insertion bed arthroscopically by utilizing the staple as a joystick [ figure 2d ] . then the staple was driven through the avulsed fragment and into the tibial plateau by hammering on to the introducer gently . the avulsed fragment was fixed with either one or two staples depending on the size of the fragment [ figure 3 ] . in comminuted fractures , the largest fragment containing most of the acl fibers was fixed with the staple and the remaining loose small fragments were removed , as it might lead to locking resulting in a fixed flexion deformity later . intra operatively , the stability of the fixation was checked by pulling the acl with a probe and full range of motion of the knee was performed . ( c ) titanium staple used to fix acl avulsion fracture ( d ) staple aiding in reduction of the avulsed fragment . ( a ) anteroposterior x - ray of left knee of a 39 years old male shows large acl avulsion ; ( b ) postoperative anteroposterior and ( c ) lateral view of the same patient shows acl fixed with 2 staples the associated ipsilateral injuries of the knee were managed simultaneously . in our seriesthree patients had tibial condyle fractures which were fixed percutaneously with screws before acl avulsion fracture fixation for better purchase of the staple [ figure 4 ] . two patients had meniscal injuries which were treated by partial menisectomies and two patients had pcl avulsion fractures which were fixed with cancellous screws by a posterior approach [ figure 5 ] . anteroposterior ( a ) and lateral ( b ) radiograph of the right knee of a 35 year old female shows acl avulsion and posterior tibial condyle fracture fixed respectively with staples ( c , d ) and percutaneous cancellous screws acl and pcl avulsion fracture of the right knee in a 47 year old male fixed with screws for pcl and staples for acl all patients were mobilized partial weight bearing for the first 4 weeks with a knee brace followed by full weight bearing along with knee bending exercises from 4 weeks postoperatively . then an active rehabilitation program was started to gradually attain the full range of movements . patients were evaluated functionally by examining for clinical signs of laxity and assessed by the lysholm score and the international knee documentation committee ( ikdc ) score at end of third and sixth month and at final followup . twenty - two patients were analyzed post - operatively and followed up for a mean period of 21 months ( range 6 - 36 months ) . complete range of motion of the knee joint at final follow up was achieved in 20 patients . two patients had a fixed flexion deformity of 5 and restricted 15 terminal flexion . at the end of final followup , anterior drawer 's test was negative in 20 patients , while 2 patients revealed grade i laxity . none of the patients had symptoms of giving away of the knee joint on daily routine activities and all patients returned to their pre - injury activity level . the mean ikdc score was 91.1 ( range 77 - 100 ) and the mean lysholm score was 95.4 ( range 83 - 100 ) . the mean time to union was 8 weeks ( range 6 - 10 weeks ) radiologically and all cases united . in our series double staple fixation was done for large avulsed fragment in 7 patients and single staple fixation in 15 patients with small fragment [ figure 3 ] . there was no difference in the functional outcome of the patients at final followup based on the number of the staples . patients with associated injuries returned back to their pre - injury occupation at time of final followup and the lysholm and ikdc scores of these patients were comparable to those of the other patients with only acl injuries [ table 1 ] . ikdc and lysholm scores in only acl injuries and acl with associated knee injuries one patient had back out of one staple 8 months after surgery in which two staples were used [ figure 6 ] . the backed out staple was removed arthroscopically and the patient was able to return to his pre - injury activity level . however we recommend removal of the staple if there is lossening or backing out radiologically . anteroposterior x - ray of the right knee showing back out of the staple in a 26 year old malethe acl is attached on the tibia to a wide depressed area in front of and lateral to the anterior tibial spine .3 acl avulsion fractures account for a majority of knee injuries when compared to pcl avulsions . avulsion fractures were classified into three types by meyers and mckeever1 as type i - undisplaced , type ii - anterior third displacement , and type iii completely displaced . different types of fixation for acl avulsions include cancellous screws , staples , sutures , k wires to bio - absorbable suture anchors .12 the conservative method carries its complications of prolonged immobilization , knee stiffness , and residual instability . open methods of fixation produce variable degree of knee stiffness due to the extensive dissection done and require long period of immobilization . acl avulsions were more common in the age group of 15 - 30 years ( n = 12 ) in our series . kendall et al found the incidence of injury in adults higher than that in children .4 song ek et al found that there is no significant difference between adults and children in terms of final range of motion in avulsion fractures that were treated surgically .5 wilfinger et al6 showed a good outcome at 1 year follow up in his study of 38 pediatric cases managed conservatively ; however , there are no studies regarding conservative management in adults . huang et al7 reported good results with high functional scores with arthroscopic suture fixation . however , technically it is a difficult procedure when compared to staple fixation . mc lennan in his series showed that lack of extension , persistence of ligamentous instability , and quadriceps wasting are side effects seen in patients treated by arthroscopic reduction and percutaneous pin fixation of acl avulsions when compared to arthroscopic staple fixation8 . ahn et al9 showed that arthroscopic reduction with modified pull - out suturing technique in displaced tibial spine acl avulsion fractures showed excellent union rate for both acute and chronic cases . in our series , five patients were operated after 72 hours and they had slightly lower scores when compared to others . however , it does not affect the final outcome . in our study the mean ikdc score was 91.1 ( 77 to 100 ) and the mean lysholm score was 95.4 ( 83 to 100 ) which is comparable to other series in the literature [ tables 2 and 3 ] . the mean ikdc score in the seven patients with associated injuries was 90.3 which was comparable to the total series mean score of 91.1 and a mean lysholm score of 94.4 which was comparable to the total series mean score of 95.4 [ table 1 ] predicting that presence of associated knee injuries when treated simultaneously does not affect the final outcome of the acl surgery . no difference in the functional outcome was found of the patients at a final follow up based on the number of the staples used to fix the fragment and indirectly the size of the avulsed fragment . song et al5 using sutures and anchors for acl avulsion obtained a lysholm score of 89.5 . a satisfactory lysholm score of 95.4 was obtained in our series with arthroscopic staple fixation . seon et al10 compared screw and suture fixation and reported a lysholm score of 91.7 and 92.7 , respectively . in medler series , avulsion fractures were fixed using acl tibial drill guide and arthroscopy and have had good results .11 good results were reported with bio absorbable suture anchors by kim et al12 in five cases . arthroscopic staple fixation facilitates earlier knee mobilization decreasing the chances of knee stiffness when compared to open techniques of fixation . arthroscopic staple fixation is a technically simple procedure when compared to the screw fixation or suturing techniques . staple fixation obviates the need for drilling or tapping and also the difficulties in insertion of long screws can be avoided . the rare chances of the screw slipping from the driver during introduction and falling into the joint cavity do exist , whereas the staple pre - threaded to the driver avoids such problems . the suture techniques described in the literature require surgical expertise in performing them and are difficult when compared to the staple fixation which can be easily reproduced . common problems encountered in this technique are communition of the avulsed fragment , interposition of menisci or the transverse inter - meniscal ligament between fracture fragments , and intra - substance acl tear combined with an avulsion fracture . when there is a severe communition of the fragment , acl fibers can be detached from the fragments and the staples might not have a good purchase and may result in early back out of the staple . in such special circumstances , also , in the cases where avulsion of acl is accompanied with acl mid - substance tear , acl reconstruction should be planned . when avulsion fracture is combined with a partial tear of acl , the largest fragment can be fixed by a staple and the torn fibers can be debrided preventing the need for acl reconstruction . this has been shown in where the two large avulsed fragments were fixed with staples and the remaining intact fibers of acl were preserved . so based on the study results we are now routinely taking preoperative mri in all cases of acl avulsions to rule out other ligament injuries , meniscal damage , and to document the integrity of the acl fibers . all patients obtained radiological union in a mean period of 8 weeks and all patients returned to their pre - injury activity level at the final follow up . based on our study , arthroscopic fixation is a preferred method to treat displaced acl avulsion fractures when compared to the previous methods of open fixation in terms of earlier mobilization , avoiding knee stiffness and residual instability . among the various arthroscopic techniques , staple fixation is a simple and effective procedure that when applied aptly gives good clinical and functional outcome .\noutput:\n" }, { "from": "agent", "value": "background : anterior cruciate ligament ( acl ) avulsion fracture is commonly associated with knee injuries and its management is controversial ranging from conservative treatment to arthroscopic fixation . the aim of our study was to assess the clinical and radiological results of arthroscopic staple fixation in the management of acl avulsion fractures.materials and methods : twenty - two patients ( 17 males and 5 females ) who underwent arthroscopic staple fixation for displaced acl avulsion fractures were analysed . the mean age was 32.2 years ( 15 - 55 years ) with a mean followup of 21 months ( 6 - 36 months ) . all patients were assessed clinically by calculating their lysholm and international knee documentation committee ( ikdc ) scores and the radiological union was assessed in the followup radiographs.results : the mean lysholm score was 95.4 ( 83 - 100 ) and the mean ikdc score was 91.1 ( 77 - 100 ) at the final followup . in 20 patients anterior drawer 's test was negative at the end of final followup while two patients had grade i laxity . associated knee injuries were found in seven cases . the final outcome was not greatly influenced by the presence of associated injuries when treated simultaneously . at final followup all the patients were able to return to their pre - injury occupationconclusion : arthroscopic staple fixation is a safe and reliable method for producing clinical and radiological outcome in displaced acl avulsion fractures ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: mercury ( hg ) contamination is an issue of global concern because numerous human activities release hg into the environment and increase its concentrations in many abiotic and biotic compartments ( 1 ) . these increases are largely the result of hg emissions from mining , cement production , and the combustion of coal for power generation ( 2 ) . this hg can be deposited near the source or transported around the globe to contaminate remote environments . once deposited onto aquatic systems , bacteria rapidly transform inorganic hg into methylmercury ( mehg ) , the form that biomagnifies up food webs to potentially toxic levels in top predators ( 1,3 ) . mercury concentrations in fish vary because of among - system differences in their biology and in the chemical and physical characteristics of their habitats , some of which are affected by human activities ( 1 ) . burning of fossil fuels has acidified freshwaters ( 4 ) and increased concentrations of hg in lakes and rivers , both of which are linked to higher hg in fishes ( 3,5 ) . sulfate is a key substrate in the methylation of hg by bacteria ( 6 ) , and recent reductions in its release and deposition , combined with some controls on local hg emissions from incinerators , contributed to lower hg in fishes ( up to 5.1 % y ; see for example ref ( 7 ) ) . although concentrations of hg in the atmosphere and precipitation recently decreased near some urban or industrial centers ( 8 ) , global anthropogenic hg emissions are projected to increase if there are no further restrictions on its use and release ( 2 ) . the objective of this study was to examine whether total hg ( thg ) concentrations in fish decreased in a region of atlantic canada known to be a biological hg hotspot , kejimkujik national park and national historic site ( knpnhs ) ( 9 ) . studies in the mid-1990s showed that the common loons ( gavia immer ) in knpnhs had two to six times more hg in their blood than loons in other parts of north america ( 10,11 ) . yellow perch ( perca flavescens ) are the preferred prey of loons ( 12 ) , and a majority of the knpnhs lakes examined in 1996 and 1997 contained perch with mean thg concentrations exceeding the 0.21 gg ( wet weight , ww ) threshold associated with a 50 % reduction in loon maximum productivity ( 13,14 ) . although concentrations of hg in precipitation declined by 2.0 % yr at knpnhs , total wet deposition of hg has not changed appreciably and concentrations of total gaseous mercury ( tgm ) at this site are increasing [ 0.3 % yr ] . in 2006 and 2007 , we revisited these acidic lakes to determine whether thg concentrations in yellow perch changed over the past decade and to relate any changes to physical or chemical characteristics of the lakes or biological characteristics of the fish . knpnhs is in southwestern nova scotia , canada ( supporting information , figure s1 ) and is not impacted by local industrial developments or other point sources of pollutants ( 16 ) . the park is downwind of major north american urban and industrial centers , and hg and acidifying substances originating from these areas are transported to and deposited in the region ( 8,13 ) . the lakes are all oligotrophic , polymictic , and acidic ( ph 6 ) but vary in size ( from 24 to 2632 ha ) , total organic carbon ( toc ) content ( 2.6 to 15.4 mgl ) , and abundance of wetlands ( 035 % of drainage basin ; tables s1 and s2 , supporting information ) . as much as possible , sampling in 2006/07 was done in a manner similar to that of the 1996/97 study ( 13 ) . fishing occurred in august and september 2006/07 ( compared to july and august 1996/97 ) . in both studies , minnow traps , trap nets , and angling were used to catch fish ; fyke nets were also used in 2006/07 . in each lake , the aim of both studies was to capture nine yellow perch from each size class consumed by common loons : 510 cm , 1015 cm , and 1520 cm ( 12 ) . fork length ( 0.1 cm ) , weight ( 0.01 g ) , and scales ( for aging ) were obtained from each fish ; all fish were kept cool on ice and then frozen within 24 h of capture . fish body condition was calculated as 100 [ weight ( g ) / length ( cm ) ] . tissues were collected and processed for hg and stable nitrogen isotopes ( , used to approximate trophic position ) as described in the supporting information and in wyn et al . was measured in each fish collected in 2006/07 and in a maximum of four composites per lake for those collected in 1996/97 . trichoptera ( limnephilidae ) or aquatic lepidoptera were collected in 2006/07 to determine whether baseline varied across lakes . surface water samples ( n = 1 / lake / date ) have been collected by helicopter in spring ( may / june ) and fall ( september / october ) from a number of lakes in knpnhs since 1983 as part of an environment canada long - term monitoring program ( 4 ) . each sample was analyzed for ph , conductivity , total nitrogen ( tn ) , total organic carbon ( toc ) , sulfate , and a suite of metals that periodically included thg ( methods described in vaidya et al . data presented are means from 19951997 and 20052007 ( n = 6 ; 3 years of semiannual sampling ) ; exceptions are detailed in table s2 . freeze - dried whole body homogenates of individual perch collected in 2006/07 were analyzed for thg using a milestone dma - 80 at the university of new brunswick ( unb ) . mean recoveries of certified reference materials were 94.62.0 % [ dorm - 2 ( dogfish muscle ) , national research council ( nrc ) , ottawa , on ; 90.3101.2 % , n = 60 ] in 2006 and 101.98.0 % [ dorm - 2 and tort - 2 ( lobster hepatopancreas ) , nrc ; 83.8121.7 % , n = 51 ] in 2007 . precision of replicate samples was 5.94.1 % ( n = 84 triplicates ) in 2006 and 1.1 blanks had a mean concentration of 0.010.01 gg dw ( n = 132 ) ; sample results were not corrected for blank values . yellow perch collected in 1996/97 were pooled within lake according to size , and then wet , whole body homogenates were analyzed for thg using the methods and quality control procedures detailed in the supporting information . all data were inspected for normality and homogeneity of variances using the kolmogorovsmirnov lilliefors test and f - ratio , respectively . when necessary , data were log10 ( thg , length , weight , conductivity , toc , tn , so4 , cl , fe ) or square - root ( al , ca , na , mn ) transformed to approximate normality . residuals were examined for all analyses , and outliers of individual fish within lakes and dates or lakes within dates were identified as those with studentized residuals exceeding an absolute value of 3 ( 19 ) . fish collected in 1996/97 were pooled prior to thg analysis ; therefore , 2006/07 data were mathematically pooled in the same way ( means of two to three fish of similar length within each size class in each lake ) before the temporal comparison . between - year , within lake differences in mean log - lengths , log - weights , and ages of yellow perch were evaluated using two - sample t - tests while temporal changes in n were assessed qualitatively due to low sample sizes and the lack of baseline for 1996/97 . differences in body condition and growth rates of perch were evaluated using analysis of covariance ( ancova ) with log - length as the dependent variable and log - weight or age as the covariate , respectively . temporal changes in thg concentrations were analyzed using polynomial regressions within each lake ( 20 ) . the model was log - thg = lc + lc + year + year * lc + year * lc ( where lc = fish length centered ) ; backward stepwise regression was used to identify terms significantly related to log - thg in each lake ( see supporting information ) . temporal trends in water chemistry ( for the periods 19951997 and 20052007 ) were evaluated using two sample t - tests . for each variable that changed through time , % changes were regressed against the physical characteristics of the lakes ( table s1 ) to evaluate whether any characteristics explained these differences . mean length of yellow perch across all lakes was 12 cm in both 1996/97 and 2006/07 , and thg concentrations were standardized to this length to facilitate comparisons . standardized thg concentrations were calculated by applying the centered log - length for each lake ( i.e , log - 12 cm mean log - lengthlake , year ) to the lake - specific polynomial regression equations ( 21 ) . size - standardized log - thg in yellow perch were compared to water chemistry parameters [ table s2 , plus cl , fe , k , mg , and mn ( data not shown ) ] by simple regressions ( general linear model , glm ) across all lakes sampled in 1996/97 or in 2006/07 ( using pooled data ) . both absolute and % change [ calculated as ( 2006/07 ) / ( 1996/97 ) 100 ] of perch thg were regressed against physical characteristics of the lakes or against % change of biological or chemical variables that showed significant differences through time ( simple glm ) . multiple stepwise regression ( retaining variables with f statistic 4 and eliminating collinearity ) was also performed across lakes to find the set of variables that best described % change of thg in perch . significant increases in thg concentrations of yellow perch were recorded for many lakes in knpnhs over the past decade ( table 1 ) . between 1996/97 and 2006/07 , mean thg concentrations increased between 10.5 and 58.3 % ( polynomial regressions , p 0.004 ) in yellow perch from ten lakes ( two were reduced to nonsignificance when one outlier was removed from each lake ) . for the remaining six lakes , thg in perch decreased ( 11.136.8 % , p 0.001 ) in three or did not change ( see table s3 and figure s2 , supporting information , for polynomial regressions ) . increases in thg occurred predominantly in the 510 and 1015 cm - sized fish , with few increases recorded for the 1520 cm perch ( figure 1 ; raw data shown in figure s3 , supporting information ) . mean thg concentrations of three size classes ( 510 , 1015 , and 1520 cm ) of yellow perch captured in 16 lakes in kejimkujik in 1996/97 and 2006/07 . the 1:1 line is shown . asterisks represent statistical within - lake differences ( * p 0.05 , * * p 0.01 , * * * p 0.001 , t - tests , ancova , or polynomial regression ) between years .2006 / 07 data mathematically pooled except in kejimkujik and peskawa lakes ; see methods for details . mean log - length and log - weight did not differ significantly ( p 0.37 ) within each lake from 1996/97 ( overall means of 11.93.6 cm and 25.7922.00 g , respectively ) to 2006/07 ( 12.23.4 cm and 26.5021.56 g ) , but there were some differences in fish age , condition , growth , and n ( table 1 ; tables s4 and s5 , supporting information ) . compared to fish captured in 1996/97 , yellow perch from 2006/07 were significantly younger in two lakes ( two - sample t - test , p 0.03 ) and had lower condition in eight lakes ( intercept of ancova , p 0.07 ; table 1 , plus kejimkujik , pebbleloggitch , and peskowesk lakes ) . growth rates of yellow perch increased between these two periods in three lakes ( ancova interaction , p 0.04 ) but decreased in another two lakes ( p 0.01 ; table s4 ) . a qualitative analysis of n also suggested that perch in seven lakes were at a higher trophic position in 2006/07 than in 1996/97 ( assuming no change in basal n ; table s5 ) . overall , of the ten lakes with increases in perch thg , six had decreases in condition , three had decreases in age , three had increases in growth , and five had increases in n . changes in water chemistry were observed for many lakes in knpnhs between 199597 and 200507 . tn concentrations in the surface water increased in all 16 lakes by 5 to 15 mgl ( p 0.07 ; table s2 ) . aqueous sulfate concentrations decreased by 0.1 to 0.3 mgl in most lakes , with significant reductions in six lakes ( p 0.04 ; table s2 ) . significant increases in ph ( by 0.1 to 0.2 units ) were measured in three lakes ( p 0.05 ; table s2 ) . alkalinity , conductivity , toc , al , ca , fe , mg , k , na , and cl were statistically similar ( p 0.19 ) in 19951997 and 20052007 for the 16 lakes ( insufficient data available to test thg ) , although small increases in toc , thg , alkalinity , and conductivity were noted for many lakes between the two periods ( table s2 ) . for all lakes , the absolute and % change of the length - standardized thg in perch were not related to any physical characteristic or to any biological or chemical variable that differed significantly over time ( i.e. , % change in age , condition , aqueous ph , tn , sulfate ; glm , p 0.12 ) . after upper silver lake was removed as an outlier , the % increase in thg in yellow perch was greatest in lakes with higher ph ( using absolute values for 20052007 ; p = 0.01 , r = 0.39 ; figure 2a ) or lower aqueous thg ( p = 0.01 , r = 0.40 ) , toc ( p = 0.01 , r = 0.39 ; figure 2b ) , conductivity ( p = 0.02 , r = 0.37 ) , or al ( p = 0.005 , r = 0.45 ) . it must be noted that aqueous thg , toc , conductivity , and al were all positively correlated ( r 0.79 ) , while also being negatively correlated to ph ( r 0.78 ) . the best stepwise model was : % change thg = 96371.11 ( 20052007 conductivity ) 147.3 ( latitude ) ( p = 0.08 , r = 0.34 ) . small fish ( 10 cm ) from the five lakes with the largest % change in thg also showed a significant decline in condition ( p = 0.026 ) that was not present in the other lakes or in the larger fish ( 15 cm , p = 0.55 ; kruskalwallis ) . percent change ( 2006/2007 compared to 1996/1997 ) of standardized thg concentrations in yellow perch captured in 15 lakes in kejimkujik versus ( a ) ph ; ( b ) toc of the lakes as measured in 20052007 ( open symbol indicates an outlier , upper silver lake , excluded from the regressions ) . between 1996/97 and 2006/07 , thg concentrations in yellow perch in knpnhs , a biological hg hotspot in northeastern north america ( 9 ) , increased an average of 29 % in ten lakes , decreased an average of 21 % in three lakes , and remained unchanged in the other three lakes . these results were unexpected considering that hg emissions from north america declined between 1995 and 2000 ( 22,23 ) , sulfate deposition and hg concentrations in precipitation decreased in the region ( 4,8 ) , and total wet hg deposition to knpnhs did not change over the same time period ( 15 ) . the change in thg in yellow perch was highest in lakes where fish condition or age decreased , or growth or n increased . percent change of thg in perch over the decade was also highest in lakes with higher ph or lower aqueous thg , toc , conductivity , and al ( as measured in 20052007 ) , and the increases occurred primarily in smaller perch ( 515 cm ) . the mean annual increase in perch thg concentrations ( 2.9 % ) for the 10 lakes in knpnhs was three times higher than the annual increase ( 0.8 % ) for fish in southern wisconsin , one of the few other north american studies showing recent hg increases ( 24 ) . the rate of increase at knpnhs was also similar to some lakes from another study in northeastern north america , where yellow perch thg increased 2.2 % y ( in 6 of 25 lakes ) in systems with large watersheds and declining ph and fish condition ( 25 ) . in some lakes in knpnhs , hg in yellow perch decreased ( 2.1 % y ) or did not change over the past decade , a trend that has also been seen in other studies ( e.g. , ref ( 7 ) ) . mercury concentrations decreased by 0.55.1 % y in walleye and yellow perch in northern wisconsin ( 7,24 ) and by 04.1 % y in yellow perch from the majority of lakes ( 12 of 25 lakes ) in the adirondacks during the past 10 to 20 years ( 25 ) . increases in fish hg concentrations in other regions were attributed to local increases in wet deposition of hg or to higher catchment inputs of hg and acidifying substances ( 24,25 ) ; however , these sources do not appear to have changed for knpnhs lakes . first , hg concentrations in precipitation have declined but its total aerial deposition in rainfall was similar over the past decade at knpnhs ( 15 ) . the precipitation and tgm data for knpnhs are also comparable to other long - term monitoring sites in the region ( 8,15 ) . it is possible , however , that other unmeasured sources of hg to the lakes have increased , e.g. , reactive gaseous hg ( rgm ) . concentrations of atmospheric tgm increased by 0.3 % yr between 1996 and 2004 at knpnhs ( 8 ) , and the highly water - soluble rgm contributes a minor portion to this atmospheric hg pool ( 26 ) . though not measured at knpnhs , fluxes of rgm to these lakes may have increased at the same time as the increase in tgm . second , while the release of stored acids and hg from catchments ( especially wetlands ) can enhance lake acidities and aqueous hg and delay recovery of freshwater ecosystems ( 1,3 ) , lake ph and toc have not changed significantly over time at knpnhs ( except for ph increases in 3 of 16 lakes ) . aqueous thg increased in some lakes , but the data are limited ( table s2 ) and may not always indicate increases in aqueous mehg ( 25 ) . mercury concentrations in fish are typically higher in lakes with lower ph , and more organic carbon and hg in the water ( 1 ) ; indeed , across lakes in knpnhs in 1996/97 , size - standardized thg in perch was higher in lakes with greater aqueous toc or thg ( as well as % wetlands in their watersheds ) and lower ph ( figure s4 , supporting information ) . however , thg in fish was not related to lake toc in 2006/07 ( figure s4 ) and , between 1996/97 and 2006/07 , the greatest increases in perch thg concentrations occurred , surprisingly , in lakes with the lowest aqueous concentrations of toc and highest ph ( figure 2 ) . although there were some slight , but nonsignificant , increases in thg and toc in the lakes over time ( table s2 ) , thg data were limited and these changes did not consistently translate into higher hg in fish . these trends suggest that increased availability , rather than just overall aqueous supply , of inorganic hg to methylating bacteria and higher concentrations of mehg at the base of the food web are contributing to the higher hg in these fish ( 1,17 ) . though not well understood , hg complexes with organic and inorganic ligands in surface waters and sediments , and its partitioning is determined by the types and characteristics of the ligands and other chemical factors such as conductivity ( 27 ) . the form of hg determines , in part , its methylation rates because small , neutral molecules are rapidly taken up by methylating bacteria ( 28 ) . though speculative , the changes in water chemistry seen here may have increased hg availability to methylating bacteria by changing binding to ligands or the type of dominant complexes present ( see for example ref ( 29 ) ) , or rates of methylation using substrates such as sulfate ( 6,28 ) . lakes with high productivity typically have low biotic hg because of dilution of hg at the base of the food web ( 30 ) . in knpnhs , increases in perch thg concentrations were observed in lakes with the lowest productivity , as indicated by conductivity ( 200507 ) . no temporal changes in conductivity were found ( other productivity measures not available ) , but tn increased significantly ( 2-fold ) in all lakes that also had increases in fish hg ( table s2 ) . it is possible that the higher tn in the most oligotrophic lakes increased mehg at the base of these food webs , but a recent study also found that nitrate inhibits hg methylation by bacteria ( 31 ) . although mehg data for primary consumers are available for 2006/07 ( 17 ) , neither water ( either time period ) nor invertebrate ( 1996/97 ) mehg data are available to evaluate temporal trends at the base of these food webs . increases in temperature or decreases in oxygen through time may have also caused the observed increases in thg in yellow perch through enhanced hg methylation and uptake at the base of the food web ( 28,32 ) . although mean annual air temperatures at knpnhs increased from 7.1 and 7.0 c in 1995 and 1996 , respectively , to 7.9 and 8.5 c in 2005 and 2006 , respectively ( 33 ) , recent studies of the 2 deepest lakes in knpnhs ( kejimkujik and peskowesk ) showed that summer temperature profiles have not changed since the 1970s ; however , hypolimnetic oxygen concentrations were significantly lower than previously reported ( 34 ) . lower oxygen can enhance hg methylation activities of anaerobic sulfate - reducing bacteria and could explain the observed increases in fish hg concentrations ( 28 ) . decreased fish condition has been linked to increases in their thg concentrations ( 25 ) , and , indeed , condition was reduced in eight knpnhs lakes , six of which had increases in yellow perch thg between 1996/97 and 2006/07 . increases in size or age , or decreases in growth , could also have caused increases in fish hg through time ( 35 ) ; however , length and weight did not change through time , significant reductions in age were found in three lakes with thg increases , and growth only declined in lakes where there were decreases or no change in fish thg . temporal changes in thg occurred primarily in the small ( 515 cm ) , young ( 7 y ; figures 1 and figure s3 ) yellow perch . the smallest size class also showed declines in condition between 1996/97 and 2006/07 , and these changes were greatest in lakes with the largest increase in thg concentrations . at this time , we can not explain the changes in condition , but they may be related to declines in the quality or quantity of available prey ( 35 ) or possibly to hg toxicity as perch concentrations approach or exceed those known to cause effects in other fishes ( 36 ) . the observed increases in thg concentrations in yellow perch in knpnhs over the past decade suggest that other species in the park are also at greater risk of hg toxicity . yellow perch are the preferred prey of common loons ( 12 ) , and loons consuming yellow perch with mean hg concentrations 0.21 gg ww exhibit a 50 % reduction in maximum productivity ( 14 ) . in 1996/97 , nine lakes had yellow perch with 12 - cm mean thg at or above the threshold , but in 2006/07 , standardized mean thg concentrations 0.21 gg occurred in 12 lakes ( 14 including outliers ; table 1 ) . in both 1996/97 and 2006/07 , yellow perch in big red lake also had a standardized thg concentration of 0.41 gg ww ( table 1 ) , the level for complete reproductive failure in loons ( 14 ) . the increase in the number of lakes exceeding the 0.21 gg threshold and nearing the 0.41 gg threshold suggests that loons in the park will experience more reductions in reproductive success and could eventually exhibit complete reproductive failure on certain lakes if these trends continue ( 14 ) . for example , thg concentrations in yellow perch in north cranberry lake could exceed 0.41 gg ww in 2013 . overall , between 1996/97 and 2006/07 , yellow perch thg concentrations increased in more than 60 % of lakes examined in knpnhs at a time when wet deposition and catchment inputs of thg or toc have not changed ; these increases were greatest in the smallest fish and in populations in lakes with the highest ph and lowest thg and toc . although the cause is currently speculative , the following factors may have played a role : ( 1 ) increased hg fluxes to the lakes as a result of higher atmospheric concentrations of rgm ; ( 2 ) increased mehg production because of higher availability of the inorganic hg pool to methylating bacteria or of conditions more favorable for methylation ( e.g. , warmer temperatures , increased tn ) ; and / or ( 3 ) reduced quality or quantity of prey available to perch . this study complements only a few others that have shown increases in thg concentrations in fish despite some reductions in emissions of hg and sulfate in north america . as such , these increases suggest that further reductions in hg and acidifying emissions from major sources , such as coal - fired generating stations ( 2 ) , should be considered to protect or restore ecosystem health in remote regions such as this one , that were previously identified as hg hotspots ( 9 ) .\noutput:\n" }, { "from": "agent", "value": "in the mid-1990s , yellow perch ( perca flavescens ) and common loons ( gavia immer ) from kejimkujik national park and national historic site ( knpnhs ) , nova scotia , canada , had among the highest mercury ( hg ) concentrations across north america . in 2006 and 2007 , we re - examined 16 lakes to determine whether there have been changes in hg in the loon s preferred prey , yellow perch . total hg concentrations were measured in up to nine perch in each of three size classes ( 510 cm , 1015 cm , and 1520 cm ) consumed by loons . between 1996/97 and 2006/07 , polynomial regressions indicated that hg in yellow perch increased an average of 29 % in ten lakes , decreased an average of 21 % in three , and were unchanged in the remaining three lakes . in 2006/07 , perch in 75 % of the study lakes had hg concentrations ( standardized to 12 - cm fish length ) equal to or above the concentration ( 0.21 gg1 ww ) associated with a 50 % reduction in maximum productivity of loons , compared with only 56 % of these lakes in 1996/97 . mercury contamination currently poses a greater threat to loon health than a decade ago , and further reductions in anthropogenic emissions should be considered to reduce its impacts on ecosystem health ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: prior and ongoing work in our groups indicates that the p7c3 class of compounds exert their neuroprotective effects by stabilizing mitrochondria against the depolarization events that are known to trigger apoptosis . nonetheless , our most robust assay involves monitoring neuroprotection of newborn hippocampal neurons in mice because this assay gives a simultaneous readout of efficacy , acute toxicity , and cell permeability . for this reason , all analogues of 1 were evaluated initially by infusing them directly into the left lateral ventricle of environmentally deprived live mice using a subcutaneously implanted osmotic minipump . compounds were delivered intracerebroventricularly ( icv ) over a 7 day period at a concentration of 10 m ( 12 l / day ) . mice were additionally dosed intraperitoneally ( ip ) daily with brdu ( 50 mg / kg ) to mark newly born hippocampal neural precursor cells . at the end of the 1 week dosing , animals were sacrificed and transcardially perfused . brain slices were stained with antibodies to brdu , and the number of surviving neural precursor cells was quantified by counting the number of brdu + cells in the hippocampal dentate gyrus . to avoid complicationsarising from the surgical implantation of the pump , we quantified neurogenesis in the hemisphere opposite to compound infusion . finally , to obtain consistent data across many animals , the number of brdu + cells was normalized to the volume of the dentate gyrus . our initial objective was to replace the aniline ring with a heterocyclic ring . previous studies had shown that the n - phenyl ring of 1 could be replaced with a 2 - pyridyl group ( giving 3 ) , but not a 3 - or 4 - pyridyl group , while maintaining activity in the in vivo hippocampal neuroprotection assay . moreover , we had discovered that fluorination of the central methylene and substitution of the n - aryl ring improved the activity , but neither change alone had substantial impact . for example , 4 ( i.e. , methoxy - 1 ) and 5 ( i.e. , fluoro - 1 ) showed similar activity as 1 . however , fluorinating the anisidine congener 4 to provide 2 substantially improved the activity in the hippocampal neuroprotection assay . in this context , we targeted 15 , a fluorinated compound containing a methoxy - substituted 2 - aminopyridine . following the approach we described for the large - scale synthesis of 2 , terminal epoxide 7 was opened with 4 - nitrobenzenesulfonyl ( 4 - nosyl , 4 - ns ) - protected 2 - methoxy -6-aminopyridine ( scheme 1 ) . surprisingly , when the resultant amino alcohol 8 was subjected to fluorination conditions with morphodast , hplc / ms and h nmr analyses indicated the formal loss of methanol . we speculated that the pyridine nitrogen displaced an activated alcohol and the cyclized pyridinium salt ( not shown ) was demethylated to yield aminopyridone 9 . the resulting secondary alcohol 10 was fluorinated to provide azido fluoride 11 , and the azide was reduced with triphenylphosphine to yield fluoroamine 12 . reaction of this amine with iodopyridine 13 ( 12 ) in the presence of cui and diketone ligand 14 provided the desired analogue 15 in high yield on a multigram scale . alternative conditions featuring pd catalysts or lacking the diketone ligand provided less than 20 % yield of the intended product . in a similar manner , amino alcohol 16 was arylated to provide 17 , the hydroxy congener of 15 . amino alcohol 16 proved to be much less reactive than fluoroamine 12 , resulting in incomplete conversion . moreover , in this case adding the diketone ligand improved the yield by only around 10 % , suggesting that the amino alcohol itself can serve as a ligand for cu . as described above , compounds were administered to mice icv over a 1 week period concurrent with dosing of brdu ip . figure 1 shows that aminopyridine 15 approximately doubled the number of surviving newborn hippocampal neurons over this time period and displayed an activity superior to that of 1 and comparable to that of 2 . several of the synthetic intermediates also displayed neuroprotective activity in this assay . while azide 11 was inactive under the conditions of this experiment , the primary amines 12 and 16 as well as the n - pyridyl amino alcohol 17 showed an increase in the number of brdu + cells compared with vehicle . however , these intermediates were less potent than 15 and even slightly less active than our initial hit 1 . we originally adopted intracerebroventricular delivery to avoid complications related to brain penetration . nonetheless , icv is clearly not an ideal method of dosing . fortunately , the optimized lead 15 showed a smooth dose response curve upon intraperitoneal ( ip ) administration . it was active at a dose of 1 mg kg day and reached its ceiling of efficacy at 10 mg kg day , results which parallel those found in the mptp model of parkinson s disease ( see below ) . control experiments demonstrated that the increase in brdu + neurons within the hippocampus was due to neuroprotection rather than increased neural stem cell proliferation ( figure s1 in the supporting information ) . compounds were administered using the indicated dose and method for 7 days , during which time mice were dosed ip daily with brdu ( 50 mg kg day ) to label newborn hippocampal neurons . data are shown as mean standard error of the mean ( sem ) . previous work had demonstrated that the preponderance of neuroprotective activity resided in a single enantiomer of the p7c3 class of compounds . the enantiomers of 18 , 19 , and 20 that are shown in scheme 2 were the more active of each pair , suggesting a specific protein - binding partner . we also determined that tertiary alcohol 21 was more active than the initial hit 1 , suggesting the presence of a hydrophobic binding site into which the methyl group could project . these observations prompted the question of which , if either , enantiomer of fluorinated analogues such as 2 and 15 would display higher potency . in particular , we sought to determine whether fluorine would act as a polar group and occupy the binding site favored by the hydroxyl group of 18 , 19 , and 20 or act as a hydrophobic group and bind similarly to 21 . unfortunately , previous attempts to fluorinate an optically active precursor to 2 provided material with 020 % ee , so developing an enantioselective synthesis remained a high priority . condensation of 3,6 - dibromocarbazole ( 6 ) with the 3 - ns - protected glycidol derivative 22 provided the epoxide ( ) - 7 in 97 % yield with 96 % ee . epoxide ring opening with azide was quantitative and provided a substrate for fluorination , ( + ) -10 . comparison with the material formed from a mitsunobu reaction with ( s ) - glycidol demonstrated that , as described by sharpless and co - workers , sulfonate 22 reacted by direct displacement of the leaving group rather than by epoxide opening / epoxide closure . consistent with previous results , we found that reaction with morphodast was not stereospecific , as azidofluoride 11 was recovered with only 63 % ee . we speculate that the common invertive mechanistic pathway was compromised by an intramolecular displacement with the carbazole nitrogen , yielding an aziridinium ion intermediate ( not shown ) . in contrast , we discovered that the reagent combination perfluorobutanesulfonyl fluoride and tetrabutylammonium difluorotriphenylsilicate ( tbat ) yielded the desired fluoride with clean inversion . the pure enantiomers of 15 were first evaluated in the mouse model of hippocampal neuroprotection after they were dosed icv . as shown in figure 2 , ( ) - 15 is highly active , whereas its enantiomer shows no neuroprotective activity in this assay . the more active enantiomer shows roughly the same activity as the racemic mixture at identical doses . we interpret this observation to mean that this in vivo assay can not resolve the 2-fold difference in concentration between , for example , a single enantiomer at 10 m and a racemic mixture at 10 m ( 5 m each enantiomer ) . x - ray crystallographic analysis of a single crystal of ( ) - 15 revealed it to be the s enantiomer ( figure s2 in the supporting information ) . interestingly , the more active fluoride is enantiomeric to the more active enantiomer in the hydroxyl series ( 1820 ) . this observation implies that the binding partner for the p7c3 class of neuroprotective chemicals contains both a hydrophobic pocket , which can be occupied by the fluoride or methyl group , and a polar pocket , which preferentially accommodates a hydroxyl group . compound was administered icv at the indicated concentration ( 0.5 l / h ) for 7 days , during which time mice were dosed ip daily with brdu ( 50 mg kg day ) to label newborn hippocampal neurons . the graph shows the mean sem for each group ( n = 4 or 5 ) . the mouse model of neurogenesis involves protecting newborn hippocampal neurons from premature apoptotic cell death . we also sought to determine whether 15 could protect mature neurons from cell death . in this context , we had previously demonstrated that 1 and 2 could protect mature dopaminergic neurons within the snc from toxicity associated with mptp . this mouse model of pd entails treating mice for 5 days with a toxic dose of mptp ( 30 mg kg day ) to initiate cell death within the snc . in the brain , mptpis oxidized to 1 - methyl -4-phenylpyridinium cation ( mpp ) , which is selectively transported into dopaminergic neurons within the snc . within these cells , mpp acts as a mitochondrial poison , generating a pathology that resembles that of parkinsonian patients . under our assay conditions , treatment with drugthis dosing regime ensured that any effect of the p7c3 class of compounds could be attributed to neuroprotective activity rather than to simply blocking the uptake or metabolism of mptp . mice were administered drug twice daily for 21 days , after which time they were sacrificed by transcardial perfusion . every fourth section was stained with antibodies specific to the enzyme tyrosine hydroxylase ( th ) . th catalyzes the oxidation of l - tyrosine to l -3,4-dihydroxyphenylalanine ( l - dopa ) , which is the first step in the biosynthesis of dopamine . accordingly , the number of th + cells provides a quantification of the neuroprotective efficacy of test compounds following mptp exposure . as shown in figure 3 , mptp effects an approximately 50 % reduction in the number of th + neurons under the chronic dosing protocol described above . consistent with our earlier reports , 2 exhibits marked neuroprotective activity , showing a significant neuroprotective effect when administered at 5 mg kg day and protection resulting in around 75 % rescue at a dose of 10 mg kg day . encouragingly , 15 demonstrated even higher neuroprotective activity than 2 , with the former showing significant activity at a dose of 1 mg kg day and rescuing over 85 % of the th + neurons at the highest dose tested ( 10 mg kg day ) . moreover , the enantiomeric specificity observed in the mptp model of pd mirrored that observed in the mouse model of neurogenesis . specifically , ( ) - ( s ) - 15 was strongly protective , while the ( + ) - r enantiomer was indistinguishable from vehicle treatment under the conditions of the assay . in this side - by - side experiment , 15 appeared to be at least as effective as 2 , a compound that has proven efficacy in several animal models of neurodegenerative disease . mice were administered mptp ( 30 mg kg day ) for 5 days . on the sixth day , treatment with drug was initiated at the indicated dose ( ip , bid , 21 days ) . bars indicate numbers of tyrosine hydroxylase - positive ( th + ) cells detected by immunohistochemical staining of the substantia nigra ( mean sem ) . asterisks indicate p 0.01 ( * ) , p 0.001 ( * * ) , or p 0.0001 ( * * * ) relative to the vehicle ( veh ) + mptp group . representative immunohistochemical pictures of th staining in the snc are shown for 5 mg kg day treatment groups . the pharmacokinetic and toxicity profiles of 15 were evaluated using both in vivo and in vitro methods . we observed nearly complete metabolic stability in the presence of murine hepatocytes ( t1 / 2240 min ) and good stability in the presence of liver microsomes ( t1 / 2 values : mouse , 49 min ; rat , 240 min ; dog , 45 min ; monkey , 81 min ; human , 117 min ) . we then monitored plasma and brain levels of the compound following intravenous , oral , or intraperitoneal dosing . as shown in table 1 , 15 exhibited a dose - proportional increase in brain levels when dosed ip . plasma bioavailability was higher when the compound was dosed ip as opposed to per os ( po ) by oral gavage , but partitioning into the brain was superior when the compound was administered by oral gavage . we noted the same effect with 2 , and thus , comparable brain levels are achieved either ip or by oral gavage . by all routes of administration ,15 was metabolically stable . while full pharmacokinetic profiling was performed with ( ) - 15 , we additionally observed indistinguishable plasma and brain concentrations for racemic and ( ) - 15 at a single time point following intraperitoneal injection of 1 , 3 , 10 , or 30 mg / kg doses ( figure s3 in the supporting information ) . these data are consistent with similar adme properties for the racemic and optically active forms of 15 . ( ) - 15 did not show significant toxicity toward the three human cancer cell lines tested ( ic5010 m vs h2122 , h2009 , and hcc44 ) . likewise , we observed 15 % inhibition of the herg channel at 50 m using a patch clamp assay . several cytochrome p450s ( cyp3a4 , -2 c9 , -3 d6 , -2 c8 , -2 b6 ) were insensitive to ( ) - 15 , while cyp1a2 and cyp2c19 showed modest ic50 values of 20 and 1.9 m , respectively . on the basis of the high protein binding of 15 ( 99 % ) , free concentrations of the drug are unlikely to reach those concentrations . finally , ( ) - 15 was screened through the nih s psychoactive drug screening program , and no compelling binding partners were identified . of 47 neuronal receptors and channels tested , only the - opioid receptor ( ic50 = 8.2 m ) and the peripheral benzodiazepine receptor [ also known as translocator protein ( tspo ) ] ( ic50 = 0.35 m ) showed any ligand displacement . the binding affinity of the former is clearly too weak to be causative for the biological activity we observed , provided that the in vitro data are predictive of binding in vivo . while the total brain concentration remains in the low micromolar range for several hours after dosing , the free concentration is much lower . moreover , while we observed enantiomeric specificity in the neurogenesis ( figure 2 ) and mptp assays ( figure 3 ) , both enantiomers of 15 bind tspo with similarly weak affinities ( 0.35 and 0.68 m ) . finally , 2 , which shows similar in vivo activity as ( ) - 15 , binds tspo more weakly ( ic50 = 2.0 m ) . a wide structural range of chemicals have been found to bind tspo , from the eponymous benzodiazapines to cholesterol to porphyrins , suggesting that it might represent a nonspecific binding partner for small molecules . moreover , a tight - binding inhibitor of this protein showed no toxicity in phase i and ii clinical trials for als and is currently in phase ii trials for spinal muscular atrophy . overall , the clean receptor binding results , which are shown in full in table s1 in the supporting information , are consistent with our observation that long - term treatment with 2 ( up to 40 mg kg day for 21 days ) or 15 ( up to 10 mg kg day for 21 days ) has no negative impact on the weight , behavior , or appearance of the treated animals . we have discovered a novel class of potent neuroprotective agents known as the p7c3 series of aminopropyl carbazoles . we have now synthesized and characterized an optimized member of this series that lacks an aniline moiety . moreover , it exhibits improved polarity and is readily available as a single enantiomer . we have demonstrated that ( ) - 15 potently blocks neuron cell death under two conditions : apoptosis of newborn hippocampal neurons and mptp - mediated killing of dopaminergic neurons in the substantia nigra . the latter effect is notable for almost complete protection in this model of parkinson s disease . future reports will describe the effect of this neuroprotective chemical in a rat model of pd and mouse models of tbi . likewise , we are actively seeking to validate the molecular target of the p7c3 class of compounds and will report the results of those studies in due course . taken together , the data suggest that ( ) - 15 is a promising candidate for treating some of the most devastating neurological disordersdisorders that are likely to increase in prevalence and currently lack effective therapies . unless otherwise stated , commercially available materials were used without further purification , and reactions were performed under a nitrogen atmosphere using freshly purified solvents . solvents were purified using solvent purification columns purchased from glass contour ( laguna beach , ca ) . all of the reactions were monitored by thin - layer chromatography ( tlc ) using e. merck silica gel 60 f254 precoated plates ( 0.25 mm ) . flash chromatography was performed with the indicated solvents using silica gel ( particle size 0.0320.063 m ) purchased from sorbent technologies . h and c nmr spectra were recorded on a varian inova 400 or 500 spectrometer . electrospray ionization mass spectrometry ( esi - ms ) was performed on an agilent 2010 lcoptical rotations were measured at 20 c on a rudolph research analytical autopol iv polarimeter . all of the synthetic compounds were confirmed to be 95 % pure by reversed - phase hplc and h nmr analyses . a solution of 6 - methoxypyridin -2-ylamine ( 206.8 mg , 1.66 mmol ) and pyridine ( 0.2 ml ) in methylene chloride ( 8.0 ml ) was stirred for 30 min before being cooled in an ice bath .4 - nitrobenzenesulfonyl chloride ( 383.9 mg , 1.73 mmol ) was added slowly to the cold stirring solution , and the ice bath was removed 10 min later . the reaction mixture was stirred overnight and then condensed , and the dark - colored mixture was purified on an automated flash chromatography system in 010 % meoh / dichloromethane ( dcm ) to provide the nosylate as a yellow liquid in 55 % yield . h nmr ( cdcl3 , 400 mhz ) : 8.34 ( d , j = 8.9 hz , 2h ) , 8.14 ( d , j = 8.9 hz , 2h ) , 7.53 ( t , j = 8.0 hz , 1h ) , 7.357.29 ( m , 1h ) , 6.81 ( d , j = 7.7 hz , 1h ) , 6.46 ( d , j = 8.2 hz , 1h ) , 3.74 ( s , 3h ) . c nmr ( cdcl3 , 100 mhz ) : 53.9 , 103.7 , 106.7 , 124.5 , 141.1 , 145.4 , 147.6 , 163.7 . esi - ms ( m / z ) : 309.9 [ m + 1 ] ; c12h11n3o5s requires 309.04 . in a modification of a published method , a stirred solution of 3,6 - dibromocarbazole ( 6.27 g , 19.3 mmol ) and powdered potassium hydroxide ( 1.30 g , 23.2 mmol ) in dimethylformamide ( dmf ) ( 100 ml ) was cooled in ice before the dropwise addition of ( r ) - glycidyl -3-nitrobenzenesulfonate ( 22 ) ( 5.01 g , 19.3 mmol ) . the ice bath was removed , and the reaction mixture was stirred overnight at ambient temperature , diluted with water , and washed several times with water and then brine . the organic layer was dried over na2so4 , filtered , and concentrated to give epoxide ( ) - 7 in quantitative yield , which was used without additional purification . h nmr ( cdcl3 , 400 mhz ) : 8.13 ( d , j = 2.0 hz , 2h ) , 7.57 ( dd , j = 8.7 , 1.8 hz , 2h ) , 7.397.31 ( m , 2h ) , 4.65 ( dd , j = 16.0 , 2.5 hz , 1h ) , 4.28 ( dd , j = 16.1 , 5.0 hz , 1h ) , 3.32 ( ddd , j = 5.2 , 2.6 , 1.3 hz , 1h ) , 2.82 ( t , j = 4.3 hz , 1h ) , 2.50 ( dd , j = 4.7 , 2.6 hz , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 45.0 , 45.1 , 50.6 , 110.7 , 112.8 , 123.4 , 123.8 , 129.5 , 139.8 . hplc ( chiralpak ad - h , 1.0 ml / min 1 % iproh / hexanes ) : tr ( major ) = 24.334.0 min ; tr ( minor ) = 48.458.6 min ; ee = 95.9 % . d20 = 5.74 ( c = 0.244 , thf ) . n - buli ( 0.65 ml of a 2.5 m solution in hexanes ) was added dropwise to a solution of n - ( 6 - methoxypyridin -2-yl ) -4-nitrobenzenesulfonamide ( 278.7 mg , 0.90 mmol ) in dmf ( 3.0 ml ) at 0 c . the solution was stirred for 15 min before the addition of 3,6 - dibromo - 9 - ( oxiran -2-ylmethyl ) - 9h - carbazole ( 7 ) ( 265.1 mg , 0.70 mmol ) . the reaction mixture was heated to 80 c for 4 h , after which more epoxide 7 ( 113.0 mg , 0.3 mmol ) was added . the reaction mixture was stirred overnight at 80 c , cooled , diluted with etoac , and washed twice with water , twice with 1 n naoh , twice more with water , and finally brine . the crude mixture was purified on an automated flash chromatography system in 010 % meoh / dcm to provide a light - orange solid in 12.5 % yield . h nmr ( cdcl3 , 400 mhz ) : 8.17 ( d , j = 1.9 hz , 2h ) , 8.04 ( d , j = 9.2 hz , 2h ) , 7.56 ( dd , j = 8.7 , 2.0 hz , 2h ) , 7.44 ( t , j = 7.9 hz , 1h ) , 7.38 ( d , j = 8.7 hz , 2h ) , 7.056.77 ( m , 2h ) , 6.48 ( d , j = 7.7 hz , 1h ) , 6.40 ( d , j = 8.1 hz , 1h ) , 4.43 ( ddd , j = 15.5 , 13.8 , 7.5 hz , 3h ) , 4.224.03 ( m , 1h ) , 3.92 ( dd , j = 15.3 , 8.9 hz , 1h ) , 3.49 ( s , 3h ) . c nmr ( cdcl3 , 100 mhz ) : 163.9 , 155.5 , 140.9 , 140.0 , 129.4 , 126.1 , 125.7 , 123.7 , 123.4 , 120.2 , 114.6 , 112.8 , 111.2 , 107.4 , 105.0 , 69.1 , 68.1 , 53.7 , 25.8 . esi - ms ( m / z ) : 732.6 [ m + hcoo ] ; c27h22br2n4o6s requires 688.0 . morphodast ( 100 l , 0.82 mmol ) was added to a solution of alcohol 8 ( 60.2 mg , 0.087 mmol ) in methylene chloride ( 2.0 ml ) . the reaction mixture was stirred overnight , and the reaction was quenched by the addition by an equivalent volume of saturated aqueous sodium bicarbonate . the combined organic layers were dried over na2so4 , filtered , concentrated , and purified by preparative tlc in 5 % meoh / dcm to provide the pyridone as a yellow solid in 21 % yield . h nmr ( cdcl3 , 400 mhz ) : 8.268.13 ( m , 2h ) , 8.06 ( d , j = 1.8 hz , 2h ) , 7.48 ( dd , j = 8.7 , 1.9 hz , 2h ) , 7.39 ( d , j = 8.7 hz , 2h ) , 7.35 ( dd , j = 9.1 , 7.5 hz , 1h ) , 7.016.80 ( m , 2h ) , 6.22 ( dd , j = 9.1 , 0.8 hz , 1h ) , 5.87 ( dd , j = 7.5 , 0.8 hz , 1h ) , 5.31 ( s , 1h ) , 5.28 ( dd , j = 7.4 , 3.2 hz , 1h ) , 4.88 ( dd , j = 15.2 , 3.1 hz , 1h ) , 4.70 ( dd , j = 15.1 , 7.5 hz , 1h ) , 4.15 ( dd , j = 10.2 , 8.3 hz , 1h ) , 3.87 ( dd , j = 10.2 , 1.3 hz , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 161.3 , 146.3 , 144.9 , 142.4 , 139.4 , 129.8 , 125.7 , 123.9 , 123.6 , 117.8 , 113.2 , 111.4 , 110.3 , 95.2 , 86.3 , 53.7 , 52.0 . esi - ms ( m / z ) : 700.6 [ m + hcoo ] ; c26h18br2n4o5s requires 655.9 . a 20 % aqueous solution of sodium azide ( 75 ml ) was added to a mixture of ( s ) - ( ) - 7 ( 7.79 g , 20.4 mmol ) and tetrahydrofuran ( thf ) ( 65 ml ) , and the mixture was heated to 75 c . a further 20 ml of a 20 % aqueous solution of sodium azide was added after 24 h to ensure complete conversion of the epoxide . the biphasic mixture was condensed under reduced pressure , diluted with etoac , and washed twice with water and then brine . the organic layer was dried over na2so4 , filtered , and concentrated to give the azido alcohol in 91 % yield , which was used without further purification . h nmr ( cdcl3 , 400 mhz ) : 8.06 ( d , j = 1.9 hz , 2h ) , 7.53 ( dd , j = 8.7 , 2.0 hz , 2h ) , 7.28 ( d , j = 8.4 hz , 2h ) , 4.26 ( dd , j = 6.1 , 1.6 hz , 2h ) , 4.234.14 ( m , 1h ) , 3.44 ( dd , j = 12.6 , 4.3 hz , 1h ) , 3.30 ( dd , j = 12.6 , 5.6 hz , 1h ) , 2.48 ( s , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 46.4 , 54.1 , 69.5 , 110.6 , 110.7 , 112.7 , 123.3 , 123.3 , 123.6 , 129.4 , 139.5 . esi - ms ( m / z ) : 466.6 [ m + hcoo ] ; c15h12br2n4o requires 421.9 . following a published procedure , diisopropylethylamine ( 7.75 ml , 44.5 mmol ) and toluene ( 140 ml ) were added alternatingly ( ca .20 portions each ) to a mixture of tetrabutylammonium difluorotriphenylsilicate ( tbat ) ( 9.50 g , 17.6 mmol ) and ( s ) -1-azido-3 - ( 3,6 - dibromo - 9h - carbazol -9-yl ) propan -2-ol ( 7.41 g , 17.5 mmol ) at room temperature . perfluoro -1-butanesulfonyl fluoride ( pbsf ) ( 6.91 ml , 38.5 mmol ) was added dropwise , and the reaction mixture was stirred overnight at ambient temperature . the mixture was concentrated and purified by automated chromatography ( sio2 , 50 % dcm / hexanes ) to provide the fluoro azide in 70 % yield as a white solid . h nmr ( cdcl3 , 400 mhz ) : 8.14 ( t , j = 2.3 hz , 2h ) , 7.647.52 ( m , 2h ) , 7.32 ( dd , j = 8.7 , 1.8 hz , 2h ) , 5.124.85 ( m , 1h ) , 4.54 ( ddt , j = 17.9 , 5.4 , 2.4 hz , 2h ) , 3.58 ( ddd , j = 17.7 , 13.5 , 4.5 hz , 1h ) , 3.40 ( ddd , j = 24.1 , 13.5 , 4.7 hz , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 44.2 ( d , jcf = 23.9 hz ) , 51.6 ( d , jc f = 23.9 hz ) , 90.0 ( d , jcf = 177.6 hz ) , 110.5 ( d , jc f = 1.3 hz ) , 113.1 , 123.5 ( d , jcesi - ms ( m / z ) : 468.7 [ m + hcoo ] ; c15h11br2fn4 requires 423.9 . hplc ( chiralpak ad - h , 1.0 ml / min 0.5 % iproh / hexanes ) : tr ( minor ) = 25.029.1 min ; tr ( major ) = 29.440.7 min ; ee = 96.2 % . triphenylphosphine ( 3.24 , 12.3 mmol ) was added to a solution of azide ( ) - ( r ) - 11 ( 5.10 g , 12.0 mmol ) in thf ( 80 ml ) . water was added to the cooled reaction mixture , and the resulting mixture was stirred for 6 h before volatile solvents were removed under reduced pressure . the viscous mixture was diluted with etoac and washed twice with water and then brine . the organic layer was dried over na2so4 , filtered , and concentrated to give a yellow waxy residue .100 ml ) , and then at 0 c 1 m hcl was added dropwise to precipitate the hydrochloride salt . the slurry was stirred for about 20 min before it was filtered and then washed with cold dcm several times and finally with hexanes . the powdery solid ( 5.29 g , quantitative ) was dried on a fritted funnel and contained less than 1 % pph3o byproduct . the salt was freebased by adding a saturated solution of sodium bicarbonate ( 90.0 ml ) to a milky mixture of the amine hcl salt ( 5.29 g ) in methylene chloride ( 90.0 ml ) with et3n ( 3.0 ml ) . the organic layer was separated , and the aqueous phase was extracted with methylene chloride . the combined organic layers were dried over na2so4 , filtered , and concentrated to give the free amine as an off - white solid . h nmr ( cdcl3 , 400 mhz ) : 8.15 ( d , j = 2.0 hz , 2h ) , 7.57 ( dd , j = 8.8 , 1.9 hz , 2h ) , 7.36 ( d , j = 8.7 hz , 2h ) , 4.85 ( dtt , j = 47.9 , 6.1 , 4.4 hz , 1h ) , 4.674.39 ( m , 2h ) , 3.222.78 ( m , 2h ) . c nmr ( cd3od , 100 mhz ) : 141.1 , 130.5 , 125.1 , 124.3 , 113.8 , 112.4 , 112.4 , 91.2 ( d , jcf = 172.4 hz ) , 45.5 ( d , jc f = 20.4 hz ) , 42.1 ( d , jc f = 20.4 hz ) . esi - ms ( m / z ) : 398.7 [ m + 1 ] ; c15h13br2fn2 requires 397.94 .1 - amino - 3 - ( 3,6 - dibromo - 9h - carbazol -9-yl ) propan -2-ol ( 16 ) ( 60.1 mg , 0.15 mmol ) , 2 - iodo -6-methoxypyridine ( 13 ) ( 35.9 mg , 0.15 mmol ) , copper ( i ) iodide ( 2.3 mg , 0.012 mmol ) , and cesium carbonate ( 100.9 mg , 0.31 mmol ) were combined in an oven - dried vial under nitrogen . dimethyl sulfoxide ( dmso ) ( 0.3 ml ) and 2,2,6,6 - tetramethyl -3,5-heptanedione ( 14 ) ( 3.5 l , 0.017 mmol ) were then added . the reaction mixture was stirred overnight at ambient temperature , diluted with etoac , and washed several times with water and then brine . the well - dried solid was dissolved in 80 % dcm / hexanes , passed through a short silica plug , and washed with dcm to remove unreacted amine . h nmr ( cdcl3 , 500 mhz ) : 8.15 ( d , j = 2.0 hz , 2h ) , 7.57 ( dd , j = 8.6 , 2.0 hz , 2h ) , 7.36 ( m , 3h ) , 6.09 ( d , j = 7.9 hz , 1h ) , 6.02 ( d , j = 7.8 hz , 1h ) , 4.55 ( bs , 1h ) , 4.454.22 ( m , 3h ) , 3.76 ( s , 3h ) , 3.50 ( d , j = 14.7 hz , 1h ) , 3.26 ( dt , j = 14.1 , 5.6 hz , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 163.3 , 157.4 , 140.2 , 139.2 , 128.8 , 123.2 , 122.9 , 112.0 , 110.5 , 99.9 , 97.4 , 70.2 , 53.3 , 46.5 , 46.3 . esi - ms ( m / z ) : 503.7 [ m + h ] ; c21h19br2n3o2 requires 503.0 . first , ( s ) - 12 ( 72.2 mg , 0.18 mmol ) , 2 - iodo -6-methoxypyridine ( 45.4 mg , 0.19 mmol ) , copper ( i ) iodide ( 2.9 mg , 0.015 mmol ) , and cesium carbonate ( 119.4 mg , 0.36 mmol ) were added to an oven - dried vial , which was then purged with nitrogen for 10 min . then dmso ( 0.36 ml ) and 14 ( 4 l , 0.019 mmol ) were added . the reaction mixture was heated at 40 c for 3 h. the cooled mixture was diluted with etoac and washed three times with a 9:1 saturated nh4cl / nh4oh solution , three times with water , and then brine . the well - dried solid was dissolved in methylene chloride and passed through a short silica plug , which removed the small amount of unreacted amine . the filtrate was condensed to give a white solid , which was purified on an automated flash chromatography system in 5080 % dcm / hexanes to provide ( ) - ( s ) - 15 as a white solid in 61 % yield with 96 % ee , which was stored under nitrogen . recrystallization to enhance the enantiomeric excess was carried out by heating a solution of 15.8 mg of the purified product in 1.0 ml of isopropanol . single crystals suitable for x - ray diffraction were grown by diffusion of hexanes into a concentrated solution of ( ) - 15 in dichloroethane ( see figure s2 in the supporting information ) . h nmr ( cdcl3 , 400 mhz ) : 8.16 ( d , j = 1.9 hz , 2h ) , 7.56 ( d , j = 1.9 hz , 2h ) , 7.35 ( t , j = 7.8 hz , 1h ) , 7.30 ( d , j = 8.7 hz , 1h ) , 6.04 ( dd , j = 32.7 , 8.0 hz , 2h ) , 5.295.02 ( dm , 1h ) , 4.654.46 ( m , 3h ) , 3.873.74 ( m , 1h ) , 3.70 ( s , 3h ) , 3.663.49 ( m , 1h ) . c nmr ( cdcl3 , 100 mhz ) : 163.7 , 156.9 , 140.3 , 139.7 , 129.5 , 123.9 , 123.4 , 112.8 , 110.7 ( d , jcf = 1.8 hz ) , 99.6 , 98.2 , 91.4 ( d , jcf = 23.9 hz ) , 43.6 ( d , jc f = 22.0 hz ) . esi - ms ( m / z ) : 505.8 [ m + 1 ] ; c22h19br2fn2o requires 505.0 . hplc ( chiralpak ia , 1.0 ml / min 100 % meoh ) : tr ( major ) = 8.3710.02 min ; tr ( minor ) = 10.2611.26 min . all of the animal studies were performed in accordance with the ethical guidelines established by ut southwestern and the university of iowa . compounds were infused icv into the left lateral ventricle of four adult ( 12 week old ) wild - type c57bl / j6 mice by means of surgically implanted alzet osmotic minipumps that delivered solution into the animals at a constant rate of 0.5 l / h for 7 days . bromodeoxyuridine ( brdu ) was injected ip at 50 mg kg day for 6 days during pump infusion . twenty - four hours after the final brdu administration , mice were sacrificed by transcardial perfusion with 4 % paraformaldehyde at ph 7.4 , and their brains were processed for immunohistochemical detection of incorporated brdu in the subgranular zone ( sgz ) . dissected brains were immersed in 4 % paraformaldehyde overnight at 4 c and then cryoprotected in sucrose before being sectioned into 40 m thick free - floating sections . unmasking of brdu antigen was achieved by incubation of tissue sections for 2 h in 50 % formamide / 2 saline sodium citrate ( ssc ) at 65 c followed by a 5 min wash in 2 ssc and subsequent incubation for 30 min in 2 m hcl at 37 c . sections were processed for immunohistochemical staining with mouse monoclonal anti - brdu ( 1:100 ) . the number of brdu + cells in the entire dentate gyrus sgz in the contralateral hemisphere ( opposite side of the surgically implanted pump ) was quantified by counting brdu + cells within the sgz and dentate gyrus in every fifth section throughout the entire hippocampus and then normalizing for dentate gyrus volume . as previously reported , adult male c57bl / 6 mice were individually housed for 1 week and then injected ip daily for 5 days with 30 mg kg day free - base mptp ( sigma ) . on day 6 , 24 h after the mice received the fifth and final dose of mptp , daily treatment with compound was initiated . mice received twice - daily doses of each compound ( or vehicle ) for the following 21 days , after which mice were sacrificed by transcardial perfusion with 4 % paraformaldehyde . the brains were dissected , fixed overnight in 4 % paraformaldehyde , and cryoprotected in sucrose for freezing by standard procedures . frozen brains were sectioned through the striatum and snc at 30 m intervals , and every fourth section ( spaced 120 m apart ) was stained with antibodies directed against tyrosine hydroxylase ( th ) ( abcam , rabbit anti - th , 1:2500 ) . diaminobenzidine was used as a chromagen , and tissue was counter - stained with hematoxylin to aid in visualization of the neuroanatomy . images were analyzed with a nikon eclipse 90i motorized research microscope with plan apo lenses coupled with metamorph image acquisition software ( nikon ) . th + neurons were counted with imagej software ( nih ) in every section by two blinded investigators , and the results were averaged and multiplied by the sectioning interval to determine the total number of th + neurons per snc . adult mice were dosed iv , ip or via oral gavage ( po ) in a total volume of 0.2 ml . whole blood was collected with a syringe and needle coated with anticoagulant citrate dextrose ( acd ) solution ( sodium citrate ) . the blood was subsequently centrifuged at 9300 g for 10 min to isolate plasma . brains were isolated from mice immediately after sacrifice , rinsed extensively with phosphate - buffered saline ( pbs ) , blotted dry , weighed , and snap - frozen in liquid nitrogen . lysates were prepared by homogenizing the brain tissue in a 3-fold volume of pbs ( weight of brain in g 3 = volume in ml of added pbs ) . the total lysate volume was estimated as the volume of added pbs plus the volume of brain . either plasma or brain ( 100 l ) was processed by addition of 200 l of acetonitrile containing 0.15 % formic acid to precipitate plasma or tissue protein and release bound drug . this mixture was vortexed for 15 s and then centrifuged at 13120 g for 5 min , and the supernatant was analyzed directly by hplc / ms / ms . standard curves were prepared by addition of compound to blank plasma or blank brain lysate . a value 3-fold above the signal obtained from blank plasma or brain lysate was designated as the limit of detection ( lod ) . the limit of quantitation ( loq ) was defined as the lowest concentration at which back - calculation yielded a concentration within 20 % of the theoretical value . pharmacokinetic parameters were calculated using the noncompartmental analysis tool of winnonlin ( pharsight ) . bioavailability was calculated as ( aucoral / auciv ) ( doseiv / doseoral ) 100 % , where auc denotes the area under the concentrationthe brain : blood ratio was calculated using auc values . protein binding of compound 15 was determined using a recently described ultracentrifugation method ; 100 % compound recovery was achieved during the assay , indicating no loss due to absorption to plastic .\noutput:\n" }, { "from": "agent", "value": "( ) - p7c3 - s243 is a neuroprotective aminopropyl carbazole with improved druglike properties compared with previously reported compounds in the p7c3 class . it protects developing neurons in a mouse model of hippocampal neurogenesis and protects mature neurons within the substantia nigra in a mouse model of parkinson s disease . a short , enantioselective synthesis provides the neuroprotective agent in optically pure form . it is nontoxic , orally bioavailable , metabolically stable , and able to cross the blood brain barrier . as such , it represents a valuable lead compound for the development of drugs to treat neurodegenerative diseases and traumatic brain injury ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: this is a retrospective cohort study whereby all patients who underwent surgery for foot drop between january 2004 and december 2007 at the neurosurgical department of a single teaching hospital in the united kingdom were included . demographic details , pathology , level of neural involvement , presence of radicular symptoms , bowel or bladder involvement , size of the herniated disc reported as per the magnetic resonance scan and operation notes , preoperative duration of foot drop or tibialis anterior weakness reported by the patient , preoperative tibialis anterior strength defined as per the medical research council ( mrc ) scale , and change in muscle strength postoperatively and at last follow - up were recorded . for purpose of inclusion in the study , foot drop was defined as weakness of tibialis anterior of mrc grade 3 or less . in case of any discrepancy in documentation of muscle strength , the one recorded by the senior member of the team was selected . cases with causes other than lumbar degenerative disease as well as those with follow - up less than 6 months were excluded from the analysis . the extent of recovery was evaluated by comparing the difference between preoperative muscle weakness and muscular strength at the last follow - up . this was analyzed as complete recovery , some improvement , no change , and deterioration , for purpose of analysis . the preoperative duration of symptoms was divided into 4 weeks , 4 to 6 weeks and 6 weeks as these times have been reported to influence outcome in previous studies . logistic regression was undertaken to assess the influence of severity and duration of preoperative weakness on muscle recovery . a total of 36 cases were identified from operative database , of which 26 met the inclusion criteria . of these , there were 15 men and 11 women . the average age at presentation was 48 years ( range 20 to 74 years ) . twenty - three patients had surgery for prolapsed intervertebral disc , and three patients had surgery for lateral recess stenosis . l45 was the operated level in 21 ( 82 % ) patients , with l5s1 implicated in five . eighty percent of the patients with disc prolapse had a moderate - sized disc ( i.e. , occupying 25 to 50 % of canal diameter . seventy percent of patients had duration of symptoms of less than 4 weeks ( range 0 to 23 ) ; of these , nine presented acutely . the left side was involved in 14 patients , the right side in 11 , and one patient had bilateral sciatica . the decision to operate was made because of neurological deficit with radicular pain in all patients after an informed discussion regarding alternative treatment .1 . microdiscectomy with or without laminectomy was undertaken , achieving a satisfactory decompression in all cases as per the operation note . postoperatively , 16 ( 61 % ) patients made a complete recovery , 7 ( 27 % ) patients were improved , and 3 ( 12 % ) patients remained unchanged ( fig . no patient had worsening of muscle weakness after the surgery . as there were only two patients above the age of 65 years and three patients with lumbar canal stenosis , analysis for age and pathology as prognostic factors was not possible . however , it was noted that all patients with lumbar canal stenosis in this study made a complete recovery . recovery of foot drop . all patients who recovered completely had a preoperative weakness of tibialis anterior for less than 4 weeks . sixteen of 18 patients with symptoms for less than 4 weeks made a complete recovery , although those with longer duration fared worse . the mean duration of symptoms in patients making complete recovery was 1.1 weeks ; in those with some improvement , it was 5.6 weeks ; and in those with no improvement , it was 18.3 weeks ( fig .3 ) . we found greater preoperative muscle strength more likely to be associated with improved outcome ( fig . , patients with severe weakness of a shorter duration could make a good recovery . adjusting for preoperative strength , preoperative duration of weakness was a significant predictor of extent of recovery ( table 1 ; odds ratio = 0.93 ; 95 % confidence interval = 0.88 to 0.98 ; p = 0.019 ) , and the model explained 50 % of the variance in outcome . , standard error ; ci , confidence interval . recovery of tibialis anterior strength at 6 months . similar studies have been performed before ; however , recovery rates at different centers have varied after surgical procedure . one of the aims of this study was to derive recovery rates specific for a standard national health service setup and patient population . we found that in our study , the recovery rates were 88 % with 61 % or patients making a complete recovery . this was comparable to other studies where recovery rates between 61 % and 84 % have been reported .567891011 the other aim of the study was identification of prognostic indicators . although girardi et al6 identified no statistically significant prognosticators , aono et al8 and postacchini et al7 found an association between preoperative severity of weakness and duration of foot drop . additionally , guigui et al10 found age 65 years , diagnosis ( stenosis versus herniated nucleus pulposus ) , monoradicular involvement , and duration 6 weeks to be associated with better recovery ; they did not identify any influence of severity of weakness on recovery . on the other hand , iizuka et al12 found diagnosis and strength to be associated with recovery but not duration . one of the other reasons for differences observed in outcome lies in the pathogenesis of disease itself . foot drop occurring secondary to acute compression is likely to benefit from decompressive surgery ; inflammation of the affected nerve root will not . reversal of foot drop depends on the time it takes for the nerve to recover once the irritant / compressive lesion has been dealt with . the perceived benefit from treatment also depends on patient factors as described in the recent study by pearson et al. 13 nevertheless , these factors should be common in all studies and patient populations . one could identify other basic differences in the literature , possibly offering an explanation for the conflicting conclusions observed the definition of foot drop , muscular paresis , and paralysis ; the way in which muscle strength was measured ; gradation of weakness ; time intervals chosen ; age groups and populations studied ; and pathological diagnoses . we used the internationally accepted mrc grading for assessment of weakness and defined foot drop precisely as weakness mrc grade 3 . we chose time interval 4 , 4 to 6 , and 6 weeks as these are relevant in clinical decision making and have previously been shown to be prognostically important . as clinically significant recovery of muscle strength has been reported up to 6 months postoperatively , we included only those patients where a minimum follow - up for this duration was available and considered the mrc score at last follow - up as against the one immediately postoperative . however , as previously described , we had only two patients aged over 65 years , three with stenosis , and none with polyradicular involvement . as such for purposes of analysis , especially in view of small overall sample size , we decided to omit these factors . as a result , we concentrated on two issues : preoperative strength and duration of weakness . duration of weakness was a significant predictor for recovery in our data . from the literature , only iizuka et al7 did not find duration to be important , but it is important to note that in their study , patients were treated very rapidly , the duration of weakness for all patients with herniated nucleus pulposus was less than 6 weeks , and only three patients had duration between 4 and 6 weeks , thus offering a potential explanation for this discrepancy . however , the duration of weakness predicted recovery adjusting for the level of motor weakness . this is important as ours as well as previous studies have reflected that preoperative strength influences outcome , and if this is not adjusted for , bias is likely . especially , we did observe findings similar to postacchini et al ,7 who found gradations of strength to be associated with extent of recovery in mild and moderate weakness , but patients with severe weakness could also make a complete recovery . in accordance with literature , our data revealed a good recovery rate for operative management of foot drop secondary to lumbar degenerative disease . we found , adjusting for preoperative muscle strength , duration of preoperative weakness was significantly associated with extent of recovery . we admit , however , that the results of this study , as any other in current literature , have to be interpreted with caution as the small number of patients per study could potentially lead to over - and underestimation of the effect of a given variable or a combination of variables . documentation of the outcome of unoperated cases would reduce such bias ; because our current records only extend to operated cases , this was not possible . with given constraints for conducting an rct , we recommend meta - analysis of existing literature to provide for more informed decision making in this regard . inclusion of historic controls and data reflecting outcomes of unoperated patients will form a valuable part of this meta - analysis .\noutput:\n" }, { "from": "agent", "value": "controversy exists regarding the timing and outcome of surgery for lumbar degenerative disease ( ldd ) associated with foot drop . in this work , we report the results of a retrospective observational study from our center . we had a sample size of 26 patients with a minimum follow - up of 6 months . of the 26 patients , 88 % improved , with complete recovery observed in 61 % . thus , our data support the view that there is good recovery from operative management of foot drop secondary to ldd . adjusting for preoperative strength , preoperative duration of weakness was a significant predictor of extent of recovery ( odds ratio = 0.93 ; 95 % confidence interval 0.88 to 0.98 ; p = 0.019 ) . the model explained 50 % of the variance in outcome in this study ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: musculoskeletal disorders are one of the most frequent health problem for people around the world . these disorders have great consequences for public health because of their severe impact on body s disability , health care expenses , sick leave ( valkenburg , 1979 ) . about 6 % of the total healthcare costs ( meerding et al . , 1998 ) and 30 % of all sick - leave days are due to musculoskeletal problems ( moncrieff and pomerleau , 2000 ) . recently , research started to demonstrate a significant relationship between physical inactivity and variety of musculoskeletal disorders and health conditions . several studies reported that regular aerobic exercise reduce the risk of suffering from various health conditions ( jakicic et al . , 2003 ; ketelhut et al . ,2004 ) . with the greater interest of the benefits of physical activity , a more health conscious population expressed interest in exercise . in school surroundings , it is natural that students majoring sports have greater chance to participate in sport activities than nonmajoring students . it is well known that regular exercise brings muscle strength and endurance which are two important components of muscular fitness . diseases and disorders of the musculoskeletal system , such as osteoporosis , osteoarthritis , bone fractures , connective tissue tears , and low back syndrome , are related to physical inactivity and a sedentary lifestyle ( heyward and gibson , 2014 ) . however , questions have been raised regarding the incidence of body deformity by participation in sports activities . for example , sport activities with high impact has been found to be a risk factor for sports injuries and deformities of the musculoskeletal system ( kujala et al . , 1997 ) . ( 2012 ) also demonstrated that body deformities are more prevalent in athletes than in nonathletes and proposed that body deformities develops during adolescence and is probably to be affected by high - impact sports practice . spinal deformity alters normal spine biomechanics leading to global balance and possible detriment to quality of life ( fong et al . , 2010 ) . imbalances of spinal alignment have been reported to relate to postural instability ( ishikawa et al . , 2009 ) . any spinal deformity has been shown to suffer from long - term functional disturbances and earlier onset back pain and disc degeneration than normal individuals . spinal deformities might be considered to relate to the lower extremities , such as knee or hip flexion and extension positions ( itoi , 1991 ) . however , no study has reported on the relationship between spinal deformities and lower extremities . therefore , the purpose of the study was ( a ) to identify the incidence of each spinal deformity and lower extremity deformity and identify the relationship of the incidence between the deformities and ( b ) to identify the effects of major and physical characteristics ( body mass index [ bmi ] , gender , age , and dominant arm ) on the development of 5 spinal deformities ( forward head , protruding abdomen , kyphosis , lordodis , and scoliosis ) and 4 lower extremity deformities ( genu valgus , genu varus , genu recurvatum , and leg length discrepancy ) . one hundred forty - seven sports major students and 54 nonmajor students participated in this study . among them 133 students were males and 68 students were females . all subjects were screened and individuals were removed from the test if they had medical problems such as lumbago and previous lower extremity fracture . each subject was asked wear pants and shirts only . the subjects were asked to answer each question on the questionnaire including college major , age , gender , height , and weight . the visual postural examination of the spine and lower extremity was conducted from anterior , posterior , lateral , and prone positions . from the anterior view , height of the shoulder on both sideswas observed . from the posterior view , any sign of scoliosis , genu valgus , genu varus , or genu recurvatum was observed . from the lateral view , any sign of forward head , protruding abdomen , kyphosis , lordosis was observed . from the prone position , a logistic regression was used to identify the association of genu valgus , genu varus , genu recurvatum , leg length discrepancy , forward head , protruding abdomen , kyphosis , lordosis , and scoliosis . independent variables were major and nonmajor , gender , and bmi converted from the height and the weight .20.0 ( ibm co. , armonk , ny , usa ) and statistical significance was set at p 0.05 for all tests . one hundred forty - seven sports major students and 54 nonmajor students participated in this study . among them 133 students were males and 68 students were females . all subjects were screened and individuals were removed from the test if they had medical problems such as lumbago and previous lower extremity fracture . each subject was asked wear pants and shirts only . the subjects were asked to answer each question on the questionnaire including college major , age , gender , height , and weight . the visual postural examination of the spine and lower extremity was conducted from anterior , posterior , lateral , and prone positions . from the anterior view , height of the shoulder on both sides was observed . from the posterior view , any sign of scoliosis , genu valgus , genu varus , or genu recurvatum was observed . from the lateral view , any sign of forward head , protruding abdomen , kyphosis , lordosis was observed . from the prone position , a logistic regression was used to identify the association of genu valgus , genu varus , genu recurvatum , leg length discrepancy , forward head , protruding abdomen , kyphosis , lordosis , and scoliosis . independent variables were major and nonmajor , gender , and bmi converted from the height and the weight .20.0 ( ibm co. , armonk , ny , usa ) and statistical significance was set at p 0.05 for all tests . table 2 shows the result of the relationship of deformity incidence between sport major and nonmajor . according to table 2 , the incidences of genu varus ( p 0.00001 ) , genu recurvatum ( p = 0.007 ) , forward head ( p 0.00001 ) , lordosis ( p 0.00001 ) , and scoliosis ( p = 0.0008 ) were significantly lower in nonmajor students compared to major students to the amount of 91 % , 76 % , 90 % , 87 % , and 73 % , respectively . the relationship of deformity incidence between gender is presented in table 3 . as shown in table 3 , the incidences of genu varus ( p = 0.0017 ) , leg length discrepancy ( p = 0.0015 ) , and forward head ( p = 0.005 ) were significantly greater in women than their counterpart to the amount of 4 , 2.3 , and 2 times , respectively . however , in genu recurvatum ( p 0.00001 ) , kyphosis ( p = 0.0001 ) , and lordosis ( p = 0.0024 ) , the incidences were significantly lower in women to the 80 % , 91.4 % , 91 % , respectively . as seen in table 4 , students in overweight ( [ bmi ] 24.5 kg / m ) showed significantly high incidence ( 4.7 times , p = 0.0044 ) in genu varus compared to students with normal bmi , and revealed significantly low incidence in genu recurvatum ( p = 0.0047 ) and protruding abdomen ( p = 0.0002 ) to the amount of 64.6 % and 79 % each in overweight students . the result of the study revealed that the incidence of spinal and lower extremity deformities in nonmajoring students showed significantly lower than sport majoring students . this result of the present investigation is consistent with the conclusion by kujala et al . it is believed that adolescent with less musculoskeletal maturity may experience a increased risk for more skeletal damage and structural abnormalities when exposed to intense levels of sports activities . deformity incidence in women was significantly high in genu varus , leg length discrepancy , and forward head . on the contrary , the incidences of genu recurvatum , khphosis , and lordosis were significantly lower in women compared to their counterparts . these differences in compensatory mechanisms should be considered when evaluating and planning spinal and lower extremity deformities for further studies . one of the risk factors of this musculoskeletal alignment is stress on the knee joint such as with exercise . chantraine ( 1985 ) hypothesized that the stress and strain on a joint caused by regular practicing of an intensive sport during adolescence may lead to a growth deformity . it is speculated that obese students participating sports activities to reduce the body weight may encounter genu varum before weight loss .\noutput:\n" }, { "from": "agent", "value": "this research was performed to identify the incidence of spinal and lower extremity deformity and to identify the relationship of the incidence between the physical characteristics . one hundred forty - seven physical education major students and 54 nonmajor students participated in this study . data collecting was performed by questionnaire and visual postural evaluation . the incidences of genu varus ( p < 0.00001 ) , genu recurvatum ( p = 0.0007 ) , forward head ( p < 0.00001 ) , lordosis ( p < 0.00001 ) , and scoliosis ( p = 0.0008 ) were significantly lower in non - major students compared to major students . the incidences of genu varus ( p = 0.0017 ) , leg length discrepancy ( p = 0.0015 ) , and forward head ( p = 0.005 ) were significantly greater in women than their counterpart . however , in genu recurvatum ( p < 0.00001 ) , kyphosis ( p = 0.0001 ) , and lordosis ( p = 0.0024 ) , the incidences were significantly lower in women . overweight ( body mass index [ bmi ] > 24.5 kg / m2 ) students showed significantly high incidence ( 4.7 times , p = 0.0044 ) in genu varus compared to students with normal bmi , and revealed significantly low incidence in genu recurvatum ( p = 0.0047 ) and protruding abdomen ( p = 0.0002 ) ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: regeneration techniques require an effective antibacterial regimen to disinfect the necrotic root canal space of immature teeth . triple antibiotic paste ( tap ) , a combination of metronidazole , ciprofloxacin , and minocycline , has been the most commonly used medicament to disinfect the root canal during endodontic regeneration . a recent review reported that tap was used in more than half of all published endodontic regeneration cases . therefore , studies have suggested eliminating the minocycline in a double antibiotic paste ( dap ) , keeping only metronidazole and ciprofloxacin , or substituting the minocycline with another antibiotic , such as clindamyxin , cefaclor , or amoxicillin . the use of ethylenediaminetetraacetic acid ( edta ) has been suggested as a final irrigation step in endodontic regeneration after the removal of the intracanal medicament . irrigation with edta has been proposed to wash out the remaining intracanal medicament and expose the collagen and other organic proteins that may improve the biological environment for endodontic regeneration . recently published in vitro studies reported a negative effect of intracanal antibiotic medicaments on hardness , resistance to fracture , and indentation properties of radicular dentin . however , no previous studies have explored the effect of antibiotic medicaments and edta on mechanical properties of radicular dentin . the predentin is a less mineralized collagen - rich dentin layer adjacent to the pulp of immature teeth with a thickness ranging from 10 to 47 m. this layer may play an important role in endodontic regeneration since minimal to no instrumentation is recommended . exploring the mechanical properties of the root canal surface that includes predentin and its underlying newly formed dentin in immature teeth is challenging due to the required metallographic preparation of dentin to perform any valid traditional mechanical test such as flexural strength , microhardness , or nanohardness . recently , a new biodent indenter was suggested to measure the indentation properties of bone , as well as root canal dentin surfaces without the need for any metallographic preparation using a technique known as reference point indentation ( rpi ) . the rpi approach relies on a reference probe , which stays on the hard tissue surface , and a test probe , which slides relative to the reference probe while indenting the measured hard tissue . some parameters obtained from biodent indenter in bone studies were suggested to correlate with and predict energy to fracture obtained through traditional mechanical testing . the purpose of this study was to investigate the effect of intracanal antibiotic medicaments used in endodontic regeneration and edta on the microindentation properties and hardness of root canal dentin surfaces and polished radicular dentin using the rpi technique and a traditional microhardness technique , respectively . ten immature human mandibular premolars previously stored in 0.1 % thymol at 4c were used within 6 months of extraction after obtaining indiana university institutional review board approval to use human teeth ( irb number ; 1305011353 ) . furthermore , each immature tooth had to have at least a 1 mm - diameter opening at the apical foramen with two - thirds of the root formed . each tooth was decoronated , and two 4 mm root dentin cylinders were obtained from the coronal and middle thirds of each root utilizing a water - cooled low - speed diamond saw ( buehler , lake bluff , il , usa ) . the pulp tissue was extirpated with a barbed broach without touching the root canal surface . four specimens were obtained from each root by sectioning each cylinder longitudinally across the maximum diameter of the root canal into two specimens without touching the root canal dentin surface . a tap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole , ciprofloxacin , and minocycline ( champs pharmacy , san antonio , tx , usa ) with sterile water ( 1 g / ml ) . a dap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole and ciprofloxacin ( champs ) with sterile water ( 1 g / ml ) . the four specimens obtained from each root were randomly assigned to three treatment groups ( tap + edta , dap + edta , and only edta ) and one hank 's balanced salt solution ( hbss ) control group . then , specimens were placed in a 2 ml conical sample cup ( fisher scientific , florence , ky , usa ) containing 0.15 ml of one of the treatment pastes or hbss for the edta and control groups . thus , the root canal dentin surface of each specimen in the antibiotic groups was covered with 0.3 mm layer of the treatment paste . after that , the specimens were taken out and rinsed thoroughly with sterile water for 30s . each specimen in the three treatment groups was immersed for 5 min in a magnetic stirrer bath that contained 5 ml of 17 % edta ( henry schein , melville , ny , usa ) followed by immersion in sterile water for 5 min before being subjected to rpi testing . rpi was performed using a biodent hfc [ figure 1 ] ( active life scientific , santa barbara , ca , usa ) with bone probe 3 ( active life scientific ) as described in a previous study . in summary , each root dentin specimen was immobilized on an acrylic block , the bone probe assembly was passively placed on the root canal surface and three indentations 1 mm apart were measured and averaged from each dentin specimen . ten indentation cycles of a 5 n indentation force were applied at a frequency of 2 hz . the most common outcome variables reported in the literature were included in this study . those are the first cycle indentation distance ( i d ) which is the distance indented on the first of the 10 cycles , the i d increase ( idi ) which is the increase in an i d from the first to the tenth cycle , and the total i d ( total i d ) which is the maximum indentation after the end of the tenth cycle . furthermore , the hardness values were estimated using first cycle i d according to the following equation of cone geometry : illustration of the major components of the biodent reference point indenter . a force generator is used to move a test probe relative to a reference probe and the force in monitored by a force transducer . a distance transducer is used to monitor the movement of the test probe relative to the reference probe . the reference probe , a modified hypodermic needle , is connected to the instrument body with a luer lock fitting . the probe assembly ( test probe and reference probe ) is disposable and replaced after every 150 indentations where p is the constant load applied = 5 newton ; r and h are the first cycle i d values obtained from biodent . forty 44 radicular dentin specimens were obtained from the coronal and middle thirds of immature roots . each specimen was embedded in acrylic resin ( varidur , buehler , lake bluff , il , usa ) with the pulpal surface facing outside . the resulting blocks ( 10108 mm ) were ground flat and polished according to a standardized protocol described in a previous study . as a final cleaning step , the polished specimens were sonicated in neutral detergent solution ( 2 % micro 90 liquid soap , international product corporation , burlington , nj , usa ) and rinsed with de - ionized water for 3 min . the specimens were randomly assigned to the three treatment groups and a control group as described in the biodent experiment . for antibiotic - treated groups , approximately 0.15 ml of tap or dap was applied on each embedded specimen to cover each specimen with a 0.3 mm layer of antibiotic paste . a close fit custom made ethylene vinyl acetate dome shaped caps ( soft - try , ultradent products , south jordan , ut , usa ) were used to cover each treated embedded specimen . then , each specimen from the three treatment groups was immersed in 17 % edta followed by sterile water as described in biodent experiment before being subjected to vickers hardness testing . microhardness measurements were performed using a vickers microhardness tester ( leco , lm247 , st . three indentations , spaced 200 m apart , were made on each specimen using a 50 - g load and a 10 - s dwell time . the representative hardness value for each specimen was obtained as the mean of the results for the three indentations . one root specimen from each group of the biodent experiment was randomly selected for scanning electron microscopy ( sem ) analysis to confirm the presence of indentations on the intact root canal surfaces after various treatments . each selected specimen was irrigated with 5 ml of distilled water , sonicated in de - ionized water for 10 min , and desiccated for 48 h. then , specimens were sputter coated for 2 min with gold / palladium and images were taken with a jeol 6390 lv scanning electron microscope ( peabody , ma , usa ) . the effect of treatment type on biodent parameters and vickers microhardness values was examined using one - way anova . pair - wise comparisons were performed using fisher 's protected least significant differences to control the overall significance level at 5 % . to satisfy the anova assumptions , ten immature human mandibular premolars previously stored in 0.1 % thymol at 4c were used within 6 months of extraction after obtaining indiana university institutional review board approval to use human teeth ( irb number ; 1305011353 ) . furthermore , each immature tooth had to have at least a 1 mm - diameter opening at the apical foramen with two - thirds of the root formed . each tooth was decoronated , and two 4 mm root dentin cylinders were obtained from the coronal and middle thirds of each root utilizing a water - cooled low - speed diamond saw ( buehler , lake bluff , il , usa ) . the pulp tissue was extirpated with a barbed broach without touching the root canal surface . four specimens were obtained from each root by sectioning each cylinder longitudinally across the maximum diameter of the root canal into two specimens without touching the root canal dentin surface . a tap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole , ciprofloxacin , and minocycline ( champs pharmacy , san antonio , tx , usa ) with sterile water ( 1 g / ml ) . a dap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole and ciprofloxacin ( champs ) with sterile water ( 1 g / ml ) . the four specimens obtained from each root were randomly assigned to three treatment groups ( tap + edta , dap + edta , and only edta ) and one hank 's balanced salt solution ( hbss ) control group . then , specimens were placed in a 2 ml conical sample cup ( fisher scientific , florence , ky , usa ) containing 0.15 ml of one of the treatment pastes or hbss for the edta and control groups . thus , the root canal dentin surface of each specimen in the antibiotic groups was covered with 0.3 mm layer of the treatment paste . after that , the specimens were taken out and rinsed thoroughly with sterile water for 30s . each specimen in the three treatment groups was immersed for 5 min in a magnetic stirrer bath that contained 5 ml of 17 % edta ( henry schein , melville , ny , usa ) followed by immersion in sterile water for 5 min before being subjected to rpi testing . rpi was performed using a biodent hfc [ figure 1 ] ( active life scientific , santa barbara , ca , usa ) with bone probe 3 ( active life scientific ) as described in a previous study . in summary , each root dentin specimen was immobilized on an acrylic block , the bone probe assembly was passively placed on the root canal surface and three indentations 1 mm apart were measured and averaged from each dentin specimen . ten indentation cycles of a 5 n indentation force were applied at a frequency of 2 hz . the most common outcome variables reported in the literature were included in this study . those are the first cycle indentation distance ( i d ) which is the distance indented on the first of the 10 cycles , the i d increase ( idi ) which is the increase in an i d from the first to the tenth cycle , and the total i d ( total i d ) which is the maximum indentation after the end of the tenth cycle . furthermore , the hardness values were estimated using first cycle i d according to the following equation of cone geometry : illustration of the major components of the biodent reference point indenter . a force generator is used to move a test probe relative to a reference probe and the force in monitored by a force transducer . a distance transducer is used to monitor the movement of the test probe relative to the reference probe . the reference probe , a modified hypodermic needle , is connected to the instrument body with a luer lock fitting . the probe assembly ( test probe and reference probe ) is disposable and replaced after every 150 indentations where p is the constant load applied = 5 newton ; r and h are the first cycle i d values obtained from biodent . ten immature human mandibular premolars previously stored in 0.1 % thymol at 4c were used within 6 months of extraction after obtaining indiana university institutional review board approval to use human teeth ( irb number ; 1305011353 ) . furthermore , each immature tooth had to have at least a 1 mm - diameter opening at the apical foramen with two - thirds of the root formed . each tooth was decoronated , and two 4 mm root dentin cylinders were obtained from the coronal and middle thirds of each root utilizing a water - cooled low - speed diamond saw ( buehler , lake bluff , il , usa ) . the pulp tissue was extirpated with a barbed broach without touching the root canal surface . four specimens were obtained from each root by sectioning each cylinder longitudinally across the maximum diameter of the root canal into two specimens without touching the root canal dentin surface . a tap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole , ciprofloxacin , and minocycline ( champs pharmacy , san antonio , tx , usa ) with sterile water ( 1 g / ml ) . a dap was prepared by mixing usp - grade antibiotic powders compounded of equal portions of metronidazole and ciprofloxacin ( champs ) with sterile water ( 1 g / ml ) . the four specimens obtained from each root were randomly assigned to three treatment groups ( tap + edta , dap + edta , and only edta ) and one hank 's balanced salt solution ( hbss ) control group . then , specimens were placed in a 2 ml conical sample cup ( fisher scientific , florence , ky , usa ) containing 0.15 ml of one of the treatment pastes or hbss for the edta and control groups . thus , the root canal dentin surface of each specimen in the antibiotic groups was covered with 0.3 mm layer of the treatment paste . after that , the specimens were taken out and rinsed thoroughly with sterile water for 30s . each specimen in the three treatment groups was immersed for 5 min in a magnetic stirrer bath that contained 5 ml of 17 % edta ( henry schein , melville , ny , usa ) followed by immersion in sterile water for 5 min before being subjected to rpi testing . rpi was performed using a biodent hfc [ figure 1 ] ( active life scientific , santa barbara , ca , usa ) with bone probe 3 ( active life scientific ) as described in a previous study . in summary , each root dentin specimen was immobilized on an acrylic block , the bone probe assembly was passively placed on the root canal surface and three indentations 1 mm apart were measured and averaged from each dentin specimen . ten indentation cycles of a 5 n indentation force were applied at a frequency of 2 hz . the most common outcome variables reported in the literature were included in this study . those are the first cycle indentation distance ( i d ) which is the distance indented on the first of the 10 cycles , the i d increase ( idi ) which is the increase in an i d from the first to the tenth cycle , and the total i d ( total i d ) which is the maximum indentation after the end of the tenth cycle . furthermore , the hardness values were estimated using first cycle i d according to the following equation of cone geometry : illustration of the major components of the biodent reference point indenter . a force generator is used to move a test probe relative to a reference probe and the force in monitored by a force transducer . a distance transducer is used to monitor the movement of the test probe relative to the reference probe . the reference probe , a modified hypodermic needle , is connected to the instrument body with a luer lock fitting . the probe assembly ( test probe and reference probe ) is disposable and replaced after every 150 indentations where p is the constant load applied = 5 newton ; r and h are the first cycle i d values obtained from biodent . forty 44 radicular dentin specimens were obtained from the coronal and middle thirds of immature roots . each specimen was embedded in acrylic resin ( varidur , buehler , lake bluff , il , usa ) with the pulpal surface facing outside . the resulting blocks ( 10108 mm ) were ground flat and polished according to a standardized protocol described in a previous study . as a final cleaning step , the polished specimens were sonicated in neutral detergent solution ( 2 % micro 90 liquid soap , international product corporation , burlington , nj , usa ) and rinsed with de - ionized water for 3 min . the specimens were randomly assigned to the three treatment groups and a control group as described in the biodent experiment . for antibiotic - treated groups , approximately 0.15 ml of tap or dap was applied on each embedded specimen to cover each specimen with a 0.3 mm layer of antibiotic paste . a close fit custom made ethylene vinyl acetate dome shaped caps ( soft - try , ultradent products , south jordan , ut , usa ) were used to cover each treated embedded specimen . then , each specimen from the three treatment groups was immersed in 17 % edta followed by sterile water as described in biodent experiment before being subjected to vickers hardness testing . microhardness measurements were performed using a vickers microhardness tester ( leco , lm247 , st . joseph , mi , usa ) on the polished pulpal side of the specimen . three indentations , spaced 200 m apart , were made on each specimen using a 50 - g load and a 10 - s dwell time . the representative hardness value for each specimen was obtained as the mean of the results for the three indentations . one root specimen from each group of the biodent experiment was randomly selected for scanning electron microscopy ( sem ) analysis to confirm the presence of indentations on the intact root canal surfaces after various treatments . each selected specimen was irrigated with 5 ml of distilled water , sonicated in de - ionized water for 10 min , and desiccated for 48 h. then , specimens were sputter coated for 2 min with gold / palladium and images were taken with a jeol 6390 lv scanning electron microscope ( peabody , ma , usa ) . forty 44 radicular dentin specimens were obtained from the coronal and middle thirds of immature roots . each specimen was embedded in acrylic resin ( varidur , buehler , lake bluff , il , usa ) with the pulpal surface facing outside . the resulting blocks ( 10108 mm ) were ground flat and polished according to a standardized protocol described in a previous study . as a final cleaning step , the polished specimens were sonicated in neutral detergent solution ( 2 % micro 90 liquid soap , international product corporation , burlington , nj , usa ) and rinsed with de - ionized water for 3 min . the specimens were randomly assigned to the three treatment groups and a control group as described in the biodent experiment . for antibiotic - treated groups , approximately 0.15 ml of tap or dap was applied on each embedded specimen to cover each specimen with a 0.3 mm layer of antibiotic paste . a close fit custom made ethylene vinyl acetate dome shaped caps ( soft - try , ultradent products , south jordan , ut , usa ) were used to cover each treated embedded specimen . then , each specimen from the three treatment groups was immersed in 17 % edta followed by sterile water as described in biodent experiment before being subjected to vickers hardness testing . microhardness measurements were performed using a vickers microhardness tester ( leco , lm247 , st . joseph , mi , usa ) on the polished pulpal side of the specimen . three indentations , spaced 200 m apart , were made on each specimen using a 50 - g load and a 10 - s dwell time . the representative hardness value for each specimen was obtained as the mean of the results for the three indentations . one root specimen from each group of the biodent experiment was randomly selected for scanning electron microscopy ( sem ) analysis to confirm the presence of indentations on the intact root canal surfaces after various treatments . each selected specimen was irrigated with 5 ml of distilled water , sonicated in de - ionized water for 10 min , and desiccated for 48 h. then , specimens were sputter coated for 2 min with gold / palladium and images were taken with a jeol 6390 lv scanning electron microscope ( peabody , ma , usa ) . the effect of treatment type on biodent parameters and vickers microhardness values was examined using one - way anova . pair - wise comparisons were performed using fisher 's protected least significant differences to control the overall significance level at 5 % . to satisfy the anova assumptions , the effect of treatment type on root canal dentin surfaces as well as on polished radicular dentin was significant for indentation properties and microhardness measurements . figure 2a shows that first - cycle i d of tap + edta and dap + edta - treated dentin were significantly greater than edta - treated and control dentin ( p 0.0001 ) . furthermore , first - cycle i d of the edta group was significantly greater than the control dentin ( p = 0.0126 ) . however , first - cycle ids of tap + edta and dap + edta - treated dentin were not significantly different from each other ( p = 0.26 ) . ( a ) mean and standard error ( se ) of the first - cycle indentation distance ( i d ) of root canal dentin exposed to various treatments and a no - treatment control group . ( b ) mean and se of estimated hardness of intact root canal dentin exposed to various treatments and a no - treatment control group . ( c ) mean and se of i d increase of intact root canal dentin exposed to various treatments and a no - treatment control group . ( d ) mean and se of total i d of intact root canal dentin exposed to various treatments and a no - treatment control group . ( e ) mean and se of vickers microhardness of polished radicular dentin exposed to various treatments and a no - treatment control group . different upper - case letters represent a significant difference the estimated hardness was significantly higher for the control group compared to edta ( p = 0.0021 ) , dap + edta ( p 0.0001 ) , and tap + edta ( p 0.0001 ) treated dentin [ figure 2b ] . in addition , the estimated hardness was significantly higher for edta treated dentin than for dap + edta ( p 0.0001 ) and tap + edta ( p 0.0001 ) treated dentin . however , no significant difference in estimated hardness was observed between dap + edta and tap + edta treated dentin ( p = 0.27 ) . figure 2c shows that the idi of tap + edta and dap + edta - treated groups were significantly greater than edta - treated and control dentin ( p 0.0001 ) . however , the idi of tap + edta and dap + edta - treated dentin was not significantly different from each other ( p = 0.17 ) , nor were edta - treated and control groups ( p = 0.63 ) . figure 2d shows that the total i d of tap + edta and dap + edta - treated dentin was significantly greater than edta - treated and control dentin ( p 0.0001 ) . however , the total i d of tap + edta and dap + edta - treated dentin was not significantly different from each other ( p = 0.26 ) . edta - treated dentin had significantly greater total i d than the control group ( p = 0.020 ) . vickers microhardness was significantly higher for the control dentin than for edta ( p = 0.0039 ) , dap + edta ( p 0.0001 ) , and tap + edta ( p 0.0001 ) treated dentin [ figure 2e ] . in addition , microhardness was higher for edta - treated dentin than for dap + edta ( p 0.0001 ) and tap + edta ( furthermore , microhardness was higher for dap + edta than for tap + edta ( pthe order of means of the four study groups was the same for both estimated hardness using rpi and vickers microhardness . scanning electron microscopy images taken at 750magnification showed the presence of microindentations as well as microcracks created during the repetitive loading . qualitatively , the micro - indentations were larger and deeper in tap + edta [ figure 3a ] and dap + edta - treated dentin [ figure 3b ] compared to edta - treated dentin [ figure 3c ] and untreated control [ figure 3d ] . ( a ) biodent indentation in triple antibiotic paste + ethylenediaminetetraacetic acid ( tap + edta ) treated root canal dentin surface . the use of various indentation techniques to determine the hardness of radicular dentin after exposure to various root canal irrigants and medicaments is a common approach in endodontic research . previous studies have used segments of polished radicular dentin due to the difficulties in performing a standardized indentation test on the actual root canal surface . however , polishing root canal dentin would remove the superficial predentin layer as well as the underlying newly formed inner radicular dentin with higher tubular density . therefore , trying to study the indentation properties of the intact root canal surface without metallographic manipulation would be more representative of the actual clinical situation . this study proposes a novel direct mechanical test to characterize the intact root canal dentin surface after exposure to antibiotic medicaments and edta solution . a traditional microhardness mechanical test was also performed in this study on polished radicular dentin to compare the magnitude of hardness reduction in both approaches . however , no statistical correlation was performed between the two types of hardness due to the different nature of the examined dentin ( unpolished intact dentin versus polished dentin ) . dentine hardness property has been related to other mechanical properties such as modulus of elasticity , compressive strength and tensile strength . indeed , a recent investigation observed that a significant reduction in root fracture resistance after 3 months intracanal treatment with dap and tap was proceeded by a significant reduction in dentin microhardness after 1 - month treatment with the same medicaments . in the current study , the percentage reduction in estimated dentin hardness from the rpi experiment were significantly higher in dap + edta ( 53 % ) and tap + edta ( 58 % ) treated dentin compared to edta - treated dentin ( 26 % ) . furthermore , the percentage reduction in hardness of dap + edta and tap + edta - treated dentin reported in this study was higher than 4 - week dap , and tap treated dentin reported in a recent study using the same rpi technique , which was 40 % and 50 % , respectively . this indicates that the use of antibiotic intracanal medicaments followed by edta irrigation have an additive effect on the reduction of dentin hardness . this could be explained by the ability of edta to chelate calcium and cause superficial dentin demineralization as well as the acidic nature of antibiotic medicaments and their ability to demineralize dentin . in this study , the percentage reduction in hardness reported using rpi of both edta - treated dentin ( 26 % ) and dap + edta ( 53 % ) treated dentin were higher than the percentage reduction in vickers hardness , which was 14 % for edta - treated dentin and 39 % for dap + edta treated dentin . this could be explained by the ability of the rpi technique to test the root canal surface dentin which is expected to be weaker due to the high density of dentin tubules in this area and the presence of predentin . on the other hand , the percentage reduction in hardness reported using rpi of tap + edta ( 58 % ) treated dentin were lower than the percentage reduction in vickers microhardness using a traditional experiment , which was 70 % for tap + edta - treated dentin . the inability of the rpi technique to detect more reduction in microhardness for tap + edta treated dentin compared to the vickers microhardness technique could be explained by the severe dentin erosive effect caused by the highly acidic nature of tap . a recent study has shown that 4 - week dentin treatment with tap followed by edta caused an average surface loss of 67 m . the estimated hardness values obtained from first - cycle i d depends mainly on the depth of penetration of the test probe into dentin in relative to the reference probe . the presence of surface loss on the measured surface after treatment may greatly decrease the first cycle i d and thus affect the magnitude of the estimated hardness . this might be considered as one of the limitations of the rpi technique when used to measure the effect of solutions / medicaments with high erosive potential on a hard tissue . the above reason could also explain the inability of the rpi technique to significantly differentiate between dap + edta and tap + edta treated dentin . a significant difference was detected between dap + edta and tap + edta treated dentin when vickers microhardness was used . the significantly lower vickers microhardness of tap compared to dap in the current study could be explained by the relatively low ph of tap compared to dap as well as the presence of minocyclin in tap , which was suggested to chelate calcium and demineralize dental hard tissues . therefore , 10 indentation cycles were used in the current study as an attempt to obtain more quantitative variables regarding the mechanical behavior of the treated dentin . the total i d variable reported in this study showed the same significant trends to first cycle i d and the estimated hardness , which might be considered as another reliable variable for differentiating between various dentin treatments . the idi of tap + edta and dap + edta - treated dentin was significantly greater than edta - treated and control dentin . recent studies on bone have shown a significant correlation between idi and modulus of toughness estimated by three - point bending mechanical tests as well as crack growth toughness . however , idi of tap + edta and dap + edta treated dentin were not significantly different from each other , nor were edta - treated and control dentin . this indicates that the idi variable was less sensitive in detecting significant differences after various dentin treatments compared to first cycle i d and total i d . in the current study , 1 g / ml of tap and dap were used since these are the concentration required to create a pasty consistency that can be applied into the infected immature root canal . some concerns have been raised regarding the use of these relatively high concentrations during endodontic regeneration . these concerns include the negative effects of tap and dap on the mechanical properties of radicular dentin and direct or indirect cytotoxic effects of tap and dap on human stem cells of the apical papilla and human dental pulp cells . the american association of endodontists has recommended the use of low concentrations of the antibiotic medicaments . however , nondiluted tap is still the most commonly used medicaments in the majority of the recently published clinical studies and there is no clinical evidence supporting the efficiency of low concentrations of antibiotic medicaments in endodontic regeneration . the use of lower concentrations of these antibiotic medicaments might be a good approach to minimize their negative effect on the mechanical properties of radicular dentin . both polished and intact root canal dentin treated with antibiotic pastes followed by edta had significant increases in indentation properties and significant reduction in microhardness compared to untreated control dentin and edta - treated dentin . however , the rpi technique was not able to significantly differentiate between dap + edta - and tap + edta - treated dentin . the currently used clinical endodontic regeneration protocols that include intracanal application of tap followed by edta irrigation may cause a significant reduction in hardness of radicular dentin ranging from 58 % to 70 % .\noutput:\n" }, { "from": "agent", "value": "objective : the objective was to investigate the effect of intracanal antibiotic medicaments followed by ethylenediaminetetraacetic acid ( edta ) on the indentation properties and hardness of radicular dentin using a biodent reference point indenter and a traditional microhardness technique , respectively.materials and methods : specimens with intact root canal dentin surfaces and polished radicular dentin specimens were obtained from immature human premolars . each type of specimen was randomly assigned ( n = 10 per group ) and treated with either double antibiotic paste ( dap ) for 4 - week followed by edta for 5 min , triple antibiotic paste ( tap ) for 4 - week followed by edta for 5 min , edta for 5 min or hank 's balanced salt solution ( control ) . the biodent reference point indentor and vickers microhardness tester were used to measure the indentation properties of root canal surfaces and the hardness of polished dentin specimens , respectively . one - way anova followed by fisher 's protected least significant differences were used for statistical analyses.results : both types of radicular dentin treated with antibiotic pastes and / or edta had a significant increase in the majority of indentation properties and a significant reduction in hardness compared to the untreated dentin . furthermore , treatment of dentin with antibiotic pastes and edta caused significant increases in indentation properties and a significant reduction in hardness compared to edta - treated dentin . however , the rpi technique was not able to significantly differentiate between dap + edta and tap + edta - treated dentin.conclusion : dentin treated with antibiotic medicaments followed by edta had a significant increase the indentation properties and significantly reduction in hardness of radicular dentin ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the use of multiparametric imaging to study the relationship between vascularisation and metabolism of tumours is emerging as a topic of interest in oncological imaging . increased vascularity and increased glucose metabolism are both important factors in the growth and metastasis of many tumours . on the other hand , poor vascularisation may lead to hypoxia which is known to contribute to resistance to radiotherapy and chemotherapy . the degree of vascularisation and metabolism represent the ultimate phenotypic expression of a range of genetic processes occurring within tumour cells . imaging the relationship between metabolism and vascularity can therefore define tumour phenotypes of potential prognostic significance . previous studies evaluating the relationship between tumour metabolism and vascularity have combined fluoro -18-deoxyglucose positron emission tomography ( fdg - pet ) images of metabolism with a range of techniques that depict tumour vascularity including o - 15 water pet , dynamic contrast - enhanced magnetic resonance and dynamic contrast - enhanced computed tomography ( dce - ct ) . of these techniques , dce - ct is most readily performed on integrated pet - ct systems remote from a cyclotron . dce - ct is increasingly used to evaluate tumour vascularity on account of the technique 's ability to provide indirect in vivo assessments of tumour angiogenesis and oxygenation . tumour perfusion values derived from kinetic analysis of dce - ct have been validated against a range of reference methods in animals and man . studies that have compared fdg - pet and dce - ct in lung , head and neck , and breast cancers have shown the ability of combined measurements to demonstrate variations in the relationship between tumour blood flow and metabolism within a single tumour type . uncoupling of tumour perfusion and metabolism has been identified as a feature of pulmonary metastases and also larger , more advanced nonsmall cell lung cancers and cancers of the head and neck . more recently , a preliminary study has suggested differences in vascular - metabolic ratios between grade 2 and grade 3 breast cancers . however , to date , studies of tumour metabolism and vascularity have been undertaken in single tumour types . there have been no studies utilising fdg - pet with dce - ct to evaluate differences in vascular - metabolic phenotype between different tumours . lymphomas are known to exhibit a range of biological characteristics that differ from those observed in other tumour types . in particular , immunohistopathological studies have suggested that hodgkin 's and non - hodgkin 's lymphomas may be less angiogenic and hypoxically driven than most solid tumours . thus , it can be anticipated that lymphomas will be unlikely to exhibit hypoxic stimulation of glucose metabolism seen as low vascularity on dce - ct and high glucose metabolism on fdg - pet . on the other hand , similar studies in colorectal cancer liver metastases have shown large amounts of hypoxic cells but with no correlation between the hypoxia marker pimonidazole and the expression of the glut - 1 glucose transporter . hence , colorectal metastases would be expected to show relatively low vascularity ( reflecting hypoxia ) and no relationship between vascularity and glucose metabolism . the purpose of this study was to undertake a preliminary comparison of tumour metabolism and vascularity in lymphoma masses and colorectal liver metastases to assess whether the differences in vascular - metabolic phenotype predicted from previous histopathological studies can be demonstrated by combining dce - ct with fdg - pet . the ability to demonstrate such intratumoural differences would provide further validation of the technique as a means to characterise the biological behaviour of tumours . the study comprised a retrospective review of image data for patients with lymphoma and colorectal cancer drawn from an imaging archive acquired between 1999 and 2002 as part of a research program evaluating angiogenesis and glucose metabolism in a range of tumour types . patients had been recruited sequentially , and all had undergone fdg - pet and ct as part of their clinical care with a single - location dce - ct added to the conventional diagnostic ct . this research program had been approved by the local ethics committee , and informed written consent had been obtained from all patients . image data was available for 19 studies in 18 patients with biopsy - proven lymphoma . eight studies acquired after lymphoma therapy were rejected for having no measurable disease at the anatomical location chosen for dce - ct . of the remaining patients , one had been studied before and after treatment giving 11 available studies in 10 patients ( 7 male , 3 female , median age : 58.1 years , range : 1783 ) . the lymphoma subtype had been recorded in the archive for only 5 patients ( 2 hodgkin 's disease , 3 non - hodgkin 's lymphoma ) . lymphoma studies were classified as active or inactive disease on the basis of the fdg uptake within the lesion on the slice corresponding to the dce - ct acquisition . a standardised uptake value for fdg ( suvfdg ) of greater than 3.0 was considered to indicate active disease , a threshold value which has previously been shown to predict a significantly poorer progression - free survival . image data was also available for 40 patients with known or suspected recurrent colorectal cancer . five cases were excluded due to incomplete image data sets , and a further 23 were excluded due to no measurable disease at the anatomical location chosen for dce - ct . thus , 12 patients were available for analysis , all of which had an fdg - avid focal liver lesion in the anatomical slice corresponding to that chosen for dce - ct . one patient had been studied before and after treatment with 5 - fluorouracil and levamisole . only the pretreatment data was used in this study . a standard pet imaging technique had been used for all patients in the archive . following a 6 - hour fast and confirmation of serum glucose levels below 10mmol / l , whole - body pet images of patients had been acquired 60 minutes after intravenous administration of 120200 mbq fdg using a ge quest dedicated pet scanner ( ge medical systems , milwaukee , wi ) . transmission scanning had been performed and attenuation corrected images ( 128x128 pixel , slice thickness of 4 mm ) produced by iterative reconstruction using the ordered subset expectation maximization ( osem ) algorithm . values for fdg uptake within the tumour , expressed as the mean standardised uptake value ( suv ) , had been determined from the pet image at the anatomical level corresponding to the dce - ct acquisition and recorded within the image archive . the dce - ct study had been incorporated into the patients ' conventional ct examination as follows : ( 1 ) a series of unenhanced images were acquired to determine the appropriate anatomical level for ( 2 ) a dynamic single - location contrast - enhanced sequence followed by ( 3 ) a conventional diagnostic portal phase examination of the chest , abdomen , and pelvis performed using an additional 100 ml bolus of contrast material at least 5 minutes after the single - location acquisition ( ct twin : elscint , haifa , israel ) . prior to imaging , contrast medium ( ioscan 10 ml , sodium diatrizoate 3.705 g ; iotech , rosebery , australia ) had been given via mouth following a 4 - hour fast . the single - location dce - ct sequence of images had been acquired at the anatomical level containing the largest transverse dimension of any focal mass lesion identified on the unenhanced images .50 ml of conventional contrast material ( iopamidol , bracco , milan ) with an iodine concentration of 370 mg / ml had been administered intravenously at 7 ml / sec through an 18 g cannula . patients had been instructed not to take deep breaths but to breathe quietly for the entire duration of the sequence . for all patients apart from 3 with lymphoma , 121 - second images with a slice thickness of 10 mm ( 120 kvp , 300 mas ) had been obtained using a cycle time of 3 seconds . for the remaining 3 patients , 601 - second images had been acquired with a cycle time of 1 sec using the same tube voltage but a reduced tube current . the ct images stored in the archive in digital imaging and communications in medicine ( dicom ) format were reanalysed for this study . ct analysis was performed by , or under the supervision of , an operator with 18 years of experience in perfusion ct imaging ( km ) blinded to the pet findings . for each patient , a region of interest ( roi ) encompassing the lymphoma mass or liver lesion was created from the precontrast ct image displayed with a constant window width and level ( 300 hu and 0 hu , resp . ) . further rois were created within the aorta and , for liver lesions , within the spleen . the changes in the x - ray attenuation within each roi following administration of contrast material were displayed as time - attenuation curves ( tacs ) . for liver lesions , the splenic tac was used to determine the time of peak splenic enhancement identifying the end of the arterial phase . only arterial phase images ( i.e. , those acquired up to the time of peak splenic enhancement ) were included in the analysis to reflect the fact that hepatic tumours receive their blood supply predominantly from the hepatic arterial system . tacs from the three studies acquired with a cycle time of 1 second underwent 3 point temporal smooth to ensure equivalence with the other studies acquired with a cycle time of 3 seconds . tumour perfusion was calculated as described by miles using the following equation : ( 1 ) tumour perfusion ( ml / min / ml ) = maximal rate of tumour enhancement ( hu / min ) peak aortic enhancement ( hu ) . this approach to measuring tumour perfusion has been validated against thermal clearance and pet using the steady - state oxygen - 15 labelled carbon dioxide method . four vascular - metabolic phenotypes were defined using the following metabolic - vascular domains categorised by threshold values for suvfdg and perfusion : ( a ) low metabolism / low perfusion , ( b ) low metabolism / high perfusion , ( c ) high metabolism / high perfusion , and ( d ) high metabolism / low perfusion . as no equivalent perfusion threshold has been determined previously , the median perfusion value of all included patients was used . the median value and interquartile range were calculated for suvfdg , perfusion , and suvfdg / perfusion . differences in these parameters between patient groups ( i ) active lymphoma ( al ) , ( ii ) inactive lymphoma ( il ) , and ( iii ) colorectal cancer liver metastases ( crm ) were tested for significance using the mann - whitney test for nonparametric data . the distribution of patients within the four vascular - metabolic phenotypes was tested for significance using fisher 's exact test for a 22 table . for all statistical tests , figure 1 comprises examples of conventional ct , perfusion ct , and fdg - pet images from patients with active lymphoma , inactive lymphoma , and colorectal liver metastases . tables 1a and 1b list the demographics and values of perfusion and fdgsuv for each patient with active lymphoma , inactive lymphoma , and colorectal liver metastases . pairwise comparisons of patient groups showed tumour perfusion was significantly higher in al ( 0.65 ml / min / ml ) than crm ( 0.37 ml / min / ml : p = .031 ) despite similar suvfdg ( 5.05 and 5.33 , resp . ) . active lymphoma masses demonstrated higher perfusion values than inactive lymphoma ( 0.24 ml / min / ml : p = .006 ) . the suvfdg / perfusion ratio was significantly higher in crm ( 15.3 min ) than il ( 4.2 min , p .01 ) . linear regression analysis showed no statistically significant correlation between these two parameters for any patient group . the distribution of cases within the metabolic - vascular domains based on thresholds of 3.0 for suvfdg and the median perfusion value of all cases ( 0.4 ml / min / ml ) was significantlynon - random ( p .00005 ) , all cases of il fell within the low metabolism / low perfusion domain whereas all cases of al exhibited high metabolism and high perfusion . colorectal liver metastases were evenly distributed between high metabolism / high perfusion and high metabolism / low perfusion domains . our results confirm that combined fdg - pet and dce - ct has the potential to evaluate vascular - metabolic relationships in lymphoma and colorectal liver metastases . the differences between active lymphoma and colorectal liver metastases demonstrated by this imaging approach are consistent with previously reported histopathological studies . our main finding was that , although active lymphoma and colorectal liver metastases exhibited similar levels of metabolism , there were significant differences in perfusion between these tumour types . in view of the previously demonstrated correlation between ct perfusion measurements and tumour oxygenation , our main finding corresponds to previous immunohistochemical studies indicating that hypoxia is uncommon in lymphoma but is a prominent feature in colorectal liver metastases . however , it is also interesting that colorectal liver metastases with low perfusion tended to exhibit suvfdg no higher than either colorectal liver metastases with high perfusion or active lymphoma . this latter finding is in contrast to previous studies in nonsmall lung cancer and head and neck tumours which have shown that low levels of tumour vascularity are often associated with particularly high levels of glucose metabolism . hypoxia is a recognised stimulus for increased glucose metabolism , which can be considered as an adaptive response to hypoxia . our finding of comparable metabolism in high and low perfusion in colorectal liver metastases suggests a failure of adaptation to hypoxia in this tumour type . this finding is also consistent with published results of histochemical analysis of colorectal liver metastases which found no correlation between the hypoxia marker pimonidazole and the expression of the glut - 1 glucose transporter . to our knowledge , this is the first study to use fdg - pet and dce - ct to compare the relationship between vascularity and metabolism in different tumour types . however , the relationships between perfusion and metabolism in lymphoma and colorectal liver metastases have been assessed previously in separate studies . used pet measurements of suv for oxygen - 15 water ( suvwater ) and fdg to assess tumour perfusion and metabolism in patients with malignant lymphomas before and after treatment , and they reported a nonlinear correlation between these two parameters . this contrasts with our study in that no correlation between perfusion and metabolism was observed in patients with either active or inactive lymphoma . nevertheless , 5 minute after injection , suvwater measurements may not be directly equivalent to absolute measurements of perfusion . amongst our patients , all cases of inactive lymphoma had perfusion values of less than 0.4 ml / min / ml . this threshold value is higher than the 0.2 ml / min / ml value previously proposed by dugdale et al . . unlike our study , the series of dugdale et al . did not classify disease activity on the basis of fdg - pet . we found no overlap in perfusion values between active and inactive cases suggesting that , for lymphoma masses , perfusion and suvfdg values may provide similar information . fukuda et al . used oxygen - 15 water measurements and fdg - pet to study perfusion and metabolism in liver tumours including six colorectal liver metastases . the median values for perfusion and fdgsuv in that study ( 0.32 ml / min / ml and 4.6 , resp . ) were very similar to those in our patient group ( 0.37 ml / min / ml and 5.3 , resp . ) . both studies also found no correlation between tumour metabolism and perfusion in colorectal liver metastases , implying that these parameters provide different information about the biological status of such tumours and highlighting the potential for combined dce - ct / fdg - pet to provide distinctive information about tumour biology . the two previous studies of perfusion and metabolism in lymphoma and colorectal liver metastases both used oxygen - 15 water pet rather than dce - ct to assess tumour vascularity . oxygen - 15 water is a diffusible tracer that will more closely reflect the delivery of nutrients to tumour tissue . the presence of arteriovenous shunts will not affect oxygen - 15 water measurements of perfusion but will contribute to perfusion values obtained with dce - ct . although not contributing to the delivery of nutrients to tumour tissue , arteriovenous shunts are an important pathological feature that distinguishes tumour vascularisation from the vascularisation of normal tissues . thus , by capturing the effects of arteriovenous shunting , dce - ct measurements of perfusion will depict an aspect of tumour vascularity not detected by oxygen - 15 water pet . the use of dce - ct can also avoid some of the artefacts that may occur with oxygen - 15 water pet such as spill over of counts from adjacent vascular structure which may be an important consideration for assessing lymphoma masses which are frequently located close to the aorta and mesenteric vessels . notwithstanding these theoretical differences , our dce - ct measurements of perfusion with crm were comparable to those reported by naumann et al . andrecent comparative study of oxygen - 15 water pet and dce - ct measurements of perfusion in solid tumours found a good correlation between the two techniques . our study identified threshold values for suvfdg ( 3.0 ) and perfusion ( 0.4 ml / min / ml ) defining vascular - metabolic domains that effectively distinguished the three patients groups ( active lymphoma , inactive lymphoma , and colorectal liver metastases ) . increasedglucose metabolism is a fundamental property of tumour cells whereas the new vessels resulting from angiogenesis are predominantly derived from the surrounding native vascular system . thus , identification of specific vascular - metabolic domains may be able to classify tumours on the basis of the biological behaviour of the tumour itself and the host 's response to the tumour . clinical studies in a range of tumour types have shown variable and inconsistent relationships between tumour perfusion and metabolism . high metabolism with low vascularity has previously been demonstrated in larger , more advanced tumours , and adjacent to areas of necrosis . furthermore , mismatching of tumour perfusion and metabolism may also be induced by cancer therapy , particularly drugs that target the tumour vasculature . our study has shown that perfusion - metabolic mismatch is also common in colorectal liver metastases . an important limitation of our study is the retrospective analysis of a relative small number of patients drawn from an imaging archive with incomplete clinical data . furthermore , improvements of dce - ct technique and pet technology have occurred since the creation of the archive . for example , a lower tube - voltage ( 80100 kvp ) is now recommended for dce - ct than that widely adopted at the time our cases were acquired , and the increased axial field of view of current ct systems allows study of greater tissue volume with the potential to reduce the impact of breathing artefacts . nevertheless , the increasing use of contrast agent during clinical pet - ct will allow dce - ct and fdg - pet to be combined in a single examination and so facilitate the larger prospective studies that are needed to confirm our findings and to evaluate the potential for combined parameters of perfusion and fdg uptake to provide prognostic information . the potential clinical implications of our study are different for lymphoma and colorectal liver metastases . for lymphoma , if the apparent equivalence of fdg - pet and dce - ct for assessing disease activity is confirmed in larger trials , it is possible that dce - ct could become a feasible technique for a preliminary assessment of residual lymphoma masses on completion of chemotherapy . perfusion values remaining above 0.4 ml / min / ml could potentially be used to select patients for consolidation therapy . on the other hand , the inability of dce - ct to image multiple tumour sites would prevent the withholding of consolidation therapy on the basis of a low perfusion value in a single target lymphoma mass because residual disease activity could be present in other lesions not assessed by dce - ct . for colorectal liver metastases , it is feasible that combined fdg - pet / dce - ct could be used to classify liver lesions in a novel way on the basis of their vascular - metabolic domain . metastases exhibiting high metabolism / high perfusion may have a different prognosis from those with high metabolism / low perfusion . this potential prognostic value is suggested by two previous studies that have used either fdg - pet or dce - ct in separate series of patients with hepatic metastases . these studies suggest that high glucose metabolism and low perfusion in crm are both associated with reduced survival . however , studies that combine imaging with clinical followup are needed to confirm the potential prognostic value of this combined technique . in summary , this preliminary study has demonstrated the potential for combined fdg - pet and dce - ct to demonstrate differences in vascular - metabolic relationships in lymphoma and colorectal liver metastases . the higher perfusion values found in active lymphoma compared to colorectal liver metastases are consistent with a higher incidence of hypoxia in colorectal liver metastases . however , this reduction in blood flow was not associated with a greater suvfdg , suggesting poor adaptation to hypoxia in this tumour type .\noutput:\n" }, { "from": "agent", "value": "purpose . to assess whether the differences in vascular - metabolic relationships between lymphoma masses and colorectal liver metastases predicted from previous histopathological studies can be demonstrated by dynamic contrast - enhanced ct ( dce - ct ) combined with fluorodeoxyglucose positron emission tomography ( fdg - pet ) . methods . dce - ct and fdg - pet studies were drawn from an imaging archive for patients with either lymphoma masses ( n = 11 ) or hepatic metastases from colorectal cancer ( crm : n = 12 ) . tumour vascularity was assessed using dce - ct measurements of perfusion . tumour glucose metabolism was expressed as the mean fdg standardised uptake value ( suvfdg ) . the relationship between metabolism and vascularity in each group was assessed from suvfdg / perfusion ratios and pearson correlation coefficients . results . an suvfdg threshold of 3.0 was used to designate lymphoma masses as active ( al , n = 6 ) or inactive lymphoma ( il , n = 5 ) . tumour perfusion was significantly higher in al ( 0.65 ml / min / ml ) than crm ( 0.37 ml / min / ml : p = .031 ) despite similar suvfdg ( 5.05 and 5.33 , resp . ) . al demonstrated higher perfusion values than il ( 0.24 ml / min / ml : p = .006 ) . suvfdg / perfusion was significantly higher in crm ( 15.3 min ) than il ( 4.2 min , p < .01 ) . there was no correlation between suvfdg and perfusion for any patient group ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: recently , the term of lamellar hole - associated epiretinal proliferation ( lhep ) was introduced by pang and colleagues to characterize a thick homogenous layer of unusual material on the epiretinal surface in eyes with lamellar macular holes ( lmh ) . high - resolution optical coherence tomography ( oct ) studies have demonstrated that eyes with lmh frequently show this epiretinal proliferation presenting as a highly reflective line with moderately reflective material filling the space between the inner border of the epiretinal proliferation and the retinal nerve fibre layer . however , pathogenesis , morphology , and clinical course of eyes with lhep are poorly understood . by recent oct studies , the presence of lhep was shown to be related to the presence of photoreceptor layer defects and poor visual acuity compared to eyes with lmh without lhep . on oct examination , lhep does not appear to have contractive properties . in general , traction forces by conventional erm become visible as retinal folds that are usually not seen in retinal layers covered by lhep . since there is little detail on cell and collagen composition of lhep , the aim of this study was to describe morphologic characteristics of lhep in eyes with lmh by correlative microscopy . correlative light and electron microscopy ( clem ) was recently proposed using immunonanogold particles of 1.4 nm diameter combined with a fluorescein moiety that both are attached to a single antibody fragment . in this studysurgically excised specimens of lhep were consecutively harvested from 10 eyes of 10 patients with lamellar macular holes during vitrectomy . all patients required surgery due to the severity of clinical symptoms such as progressive visual loss . patients ' records were reviewed for age , gender , previous ocular surgery , and preoperative history such as trauma . all specimens were obtained from patients who were part of a recent retrospective oct study reporting on clinical course of 112 operated and nonoperated eyes with lamellar macular holes and macular pseudoholes . clinical data of patients and volume b - scans of high - resolution oct examinations ( spectralis oct , heidelberg engineering , heidelberg , germany ) were reevaluated in order to exclusively include eyes with presence of lhep . this study was approved by the institutional review board and ethics committee and was conducted according to the tenets of the declaration of helsinki . surgery was recommended if bcva decreased to logmar 0.3 or more , if bcva decreased 2 snellen lines or more during the preoperative follow - up period , and if the patient experienced a significant impairment of the quality of life . if necessary , a posterior vitreous detachment ( pvd ) was induced by suction with the vitrectomy probe around the optic nerve head . the posterior hyaloid was detached from the retina and pvd was extended to the periphery with the vitreous being removed at least up to the equator . for removal of lhep , intraocular end - gripping forceps were used . for ilmpeeling , a 0.25 mg / ml solution of brilliant blue ( brilliant peel , fluoron gmbh , neu - ulm , germany ) was used . the vitreous cavity was then filled with a tamponade of either 15 % hexafluoroethane ( c2f6 ) gas - air mixture , or air , or balanced salt solution . infrequently , patients were instructed to keep a face - down position for at least 2 days . for fixationindirect immunocytochemistry was performed for all specimens after flat - mount preparation following interference and phase contrast microscopy . if necessary , large specimens were divided into pieces in accordance with their size in order to label excised tissue of each patient with all antibodies . primary antibodies for glial and retinal cells ( antiglial fibrillary acidic protein ( anti - gfap ) , dako , hamburg , germany ) ; for hyalocytes ( anti - cd45 and anti - cd64 , santa cruz biotechnology , heidelberg , germany ) ; for myofibroblasts ( anti- - smooth muscle actin ( anti- - sma ) , santa cruz biotechnology , heidelberg , germany ) ; and for extracellular matrix ( anticollagen type i ( anti - col - i ) , santa cruz biotechnology , heidelberg , germany ; anticollagen type ii ( anti - col - ii ) , biotrend , cologne , germany ) were added and incubated over night at room temperature . as second antibody , fluoronanogold ( fab - fragments , nanoprobes , yaphankpostfixation with 2 % glutaraldehyde was following . preparing negative controls , specimens with large area and multilayered cell proliferationwere cut into half in order to use one part for labelling procedures and the other part for negative control preparation . the primary antibody was substituted with both diluent and isotype controls ( igg2a monoclonal mouse antibodies , x0934 , dako , hamburg , germany ; m5409 , sigma - aldrich , taufkirchen , germany ) . following fluorescence microscopic analysis ( leica dm 2500 , wetzlar , germany ) at magnifications between 50 and 400 , specimens were processed for transmission electron microscopy . postfixation in osmium tetroxide 2 % and uranyl acetate as well as dehydration and embedding in epon 812 was following . ultrathin sections of 60 nm were obtained by series - sectioning and were contrasted with uranyl acetate and lead citrate . analysis and imaging of 5 grids ( each with 69 ultrathin sections ) per specimen were performed using a transmission electron microscope zeiss em 9 s - 2 ( zeiss , jena , germany ) . this is a series of 10 surgically excised specimens of lhep obtained during vitrectomy from eyes with lamellar macular holes . patients ' mean age was 706 years ( median , 70 years ; range , 6382 years ) . preoperatively median bcva of eyes with lmh was logmar 0.40 ( mean 0.410.13 sd ) and increased postoperatively to median bcva of logmar 0.30 ( mean 0.340.19 sd ) during a mean follow - up period of 8.6 months ( median 10 months ; range , 315 months ) . in detail , 6 of 10 patients improved visual acuity , whereas 3 of 10 patients lost vision , and in one patient bcva remained unchanged . from the eyes with lhep only , 4 of 5 eyes improved bcva , whereas one of 5 patients lost vision acuity . considering eyes with a combination of both lhep and an extrafoveal conventional erm , 2 of 5 patients improved vision acuity . two of 5 patients lost bcva and one patient was stable . at time of surgery , all of the phakic eyes underwent combined vitrectomy with cataract extraction and intraocular lens implantation . regarding the presence of posterior vitreous detachment ( pvd ) , a complete pvd was seen in 4 of 10 eyes as intraoperatively assessed by the surgeon . a partial pvd was documented in 4 of 10 eyes , and an attached posterior vitreous was found in 2 of 10 eyes . postoperatively , none of the eyes developed a full - thickness macular hole and no persistent macular edema was noted . in sd - oct examinations , lhep was directly located at the macular defect ( figures 1 ( a ) and 1 ( b ) ) . in half of all eyes , a combination of both lhep and a conventional erm with contractive properties was seen . if present , conventional erm was found extrafoveal with some distance to the foveal defect ( figure 1 ( c ) ) . preoperatively , defects of the ellipsoid zone were detected in 8 of 10 eyes ( table 1 ) . in 2 eyes , defects of the external limiting membrane ( elm ) analysing flat - mounted specimens , positive immunostaining for anti - gfap and for the hyalocyte cell markers anti - cd45 and anti - cd64 was seen in all eyes with lhep ( table 1 , figure 2 ) . moreover , a colocalisation of anti - gfap with anti - cd64 as well as anticollagen type i was seen in several specimens . in negative control specimens , , the ilm was characterized by its undulated retinal side and the smooth vitreal side . in epiretinal cell proliferation , fibroblasts and hyalocytes were the predominant cell types ( figure 3 ) . fibroblasts were characterized by their abundant rough endoplasmatic reticulum , prominent golgi complex , and a fusiform shape of the cell body and nucleus . hyalocytes were distinguished by their lobulated cell nuclei , intracellular vacuoles , vesicles , and mitochondria as well as long cell fibers . myofibroblasts containing cell fibers with contractile forces were rarely found . in the collagen matrix , native vitreous collagen ( nvc ) was predominant and identified as major type of collagen . it is characterized by a regular arrangement of fibrils with a collagen fibril diameter of less than 16 nm . newly formed collagen ( nfc ) with irregular fibril arrangement and fibril diameter of more than 16 nm was seen as well . in nvc , fibrous long spacing collagen ( flsc ) negative controls did show neither specific labelling of cellular structures nor extracellular components by immunonanogold labelling . this is the first correlative light and electron microscopic study presenting histopathologic data of lhep by using application of immunonanogold . correlative light and electron microscopy was recently reported to improve visualization of cells and extracellular matrix in epiretinal membranes by using fluoronanogold as secondary antibody . it composes an immunonanogold particle of 1.4 nm diameter that is combined with a fluorescein moiety and a single antibody fab - fragment . by application of immunonanogold particles , we were able to analyse the same cellular and extracellular components of lhep by fluorescence and electron microscopy . lamellar hole - associated epiretinal proliferation was recently suggested to be primarily driven by a proliferation of mller cells onto the inner retina originating from the middle layers of the retina . in this study , we demonstrated gfap - positive cells in lhep . this finding is in accordance with immunohistological results of parolini and colleagues , who also presented cells with positive immunostaining of anti - gfap . in the majority of studies , immunoreactivity for gfap in epiretinal membranes was usually interpreted as an indicator for the presence of glial cells . however , electron microscopy revealed fibroblasts as predominant cell type in this analysis . of note , fibroblasts and hyalocytes were occasionally described to be gfap - positive . several species were found to present gfap - positive hyalocytes , including porcine , pectineal , and bovine hyalocyte cell lines . therefore , we hypothesize that vitreous derived cells rather than cells of glial origin may play a major role in pathogenesis of lmh with lhep . in this series , fibroblasts were often seen densely packed in cell agglomerations , mostly situated on vitreous collagen strands . our observations are in accordance with sd - oct examinations demonstrating a thick homogenous layer of unusual material on the epiretinal surface in eyes with lamellar macular holes that does not show contraction signs . predominance of vitreous collagen in specimens of lhep was reported by parolini et al . and has been confirmed by this study . native vitreous collagen fibrils were arranged as thick collagen strands often dispersed with fibrous long spacing collagen that is known to represent a remodelling process of vitreous collagen . thus , lhep appears to primarily consist of vitreous derived cells proliferating on vitreous collagen strands that are marked by degradation and remodelling of collagen components . in this study , the majority of eyes with lhep showed defects of the ellipsoid zone in preoperative sd - oct examinations , which is in accordance with previous reports on disruptions of the outer photoreceptor layer in lmh . furthermore , recent studies demonstrated that the presence of lhep correlated with defects of the ellipsoid zone and the elm layer . however , it is still unknown why eyes with lmh do not respond to erm / ilm peeling as positively as expected . differences in contractive properties of epiretinal cell proliferation might partly explain these postoperative findings and should be taken into consideration when recommending surgical intervention in eyes with lmh . in this study , half of all eyes with lhep were accompanied by eccentric foci of conventional erm . in these cases of lmh , macular surgery might be indicated and surgical outcome of these eyes should be addressed in further studies .\noutput:\n" }, { "from": "agent", "value": "purpose . to describe morphology of lamellar hole - associated epiretinal proliferation ( lhep ) removed from eyes with lamellar macular holes ( lmh ) . methods . based on optical coherence tomography data , 10 specimens of lhep were removed from 10 eyes with lmh during standard vitrectomy . specimens were prepared for correlative light and electron microscopy ( clem ) using an immunonanogold particle of 1.4 nm diameter that was combined with a fluorescein moiety , both having been attached to a single antibody fragment . as primary antibodies , we used antiglial fibrillary acidic protein ( gfap ) , anti - cd45 , anti - cd64 , anti- - smooth muscle actin ( - sma ) , and anticollagen type i and type ii . results . in lhep , gfap - positive cells possess ultrastructural characteristics of fibroblasts and hyalocytes . they represent the major cell types and were densely packed in cell agglomerations on vitreous collagen strands . epiretinal cells of lhep rarely demonstrated contractive properties as - sma - positive myofibroblasts were an infrequent finding . conclusion . clem indicates that epiretinal cells in lhep might originate from the vitreous and that remodelling processes of vitreous collagen may play an important role in pathogenesis of eyes with lmh ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: type 1 diabetes mellitus ( t1 dm ) , previously known as insulin - dependent , is a chronic disease that usually develops during childhood and adolescence . the disease is characterized by a deficit of insulin production and requires lifelong administration of insulin injections for survival . uncontrolled diabetes can seriously damage many of the body 's systems , especially the nerves and blood vessels , leading over time to severe chronic conditions and early death with a large social and economic impact . as one of the major chronic diseases during the age of development , with about 350 million people affected worldwide , the diabetes mellitus represents a public health problem in both low - and high - income countries . the incidence varies significantly among countries , and even among regions within countries . during the first half of the 1990s , the overall age - adjusted incidence rate of t1 dm varied globally from 0.1 in china and venezuela to 37 per 100,000 / year in finland . in finland , after a modest increase up until 1988 , the incidence increased annually by 3.6 % until 2005 , followed by a plateau until the end of 2011 ( average incidence 20062011 : 62.5 per 100,000 person - years , 68.4 per 100,000 person - years among boys , and 55.4 per 100,000 person - years among girls ) . a 2008 study conducted in 19 european countries showed that the incidence among children aged 15 years in the 20042008 period varied from 5.8 per 100,000 / year in macedonia to 36.6 per 100,000 / year in sweden . more recent estimations assessed that in the united states in 20120.25 % of people aged 20 years were diagnosed with diabetes . in norway , in the period 20042012 the average incidence rate of t1 dm in children below 15 years of age was 32.7 per 100,000 person - years . in italy , although several authors have reported t1 dm incidence data from selected geographical areas since the 1980s , national incidence rates are still missing . in their study , vichi et al . estimated a mean nationwide incidence rate of 13.4 among italian children aged 04 years in the period 20052010 , using the first hospital admission for t1 dm as a proxy of a new t1 dm case . in the veneto region , identified as an area with intermediate - high risk for t1 dm , an incidence rate of 16.5 per 100,000 person - years was reported among children aged 018 years in the 20082012 period . in sardinia , the highest - incidence italian region , the systematic collection of diabetes mellitus cases provides a good instrument to define the spatial and temporal trends of the disease and to assess the needs in terms of health care intervention . estimating the burden of t1 dm by compiling a registry is an opportunity because it is particularly suitable for being captured . the disease is neither too severe nor too frequent ; it also has a classic set of symptoms , and it can be rapidly diagnosed by simple tests . basic information needed for registration is name , date of birth , date of diagnosis , place of residence , and ascertainment status . in 1997 , a registry of childhood type 1 diabetes mellitus in italy ( ridi ) was established to coordinate preexisting registries and to promote the setting up of new local registries . until now , ridi has included a total of seven regional registries ( liguria , marche , umbria , lazio , abruzzo , campania , and sardinia ) and five provincial registries ( trento , turin , pavia , modena , and florence - prato ) . in apulia , a southeastern italian region of about 4,000,000 inhabitants , new cases of t1 dm in patients aged 017 yearshave been recorded in the registry of childhood - onset diabetes ( rcod ) since 2009 . this study aimed at estimating the incidence of t1 dm with onset before 18 years of age in apulia region by using routinely available epidemiological data sources and assessing the sensitivity of the regional childhood - onset diabetes registry in the period 20092013 . in order to estimate the incidence of t1 dm we performed a retrospective study by using three data sources : hospital discharge registry ( hdr ) , which collects data on discharge diagnoses ( one main and up to five secondary diagnoses ) and procedures of all patients admitted to hospitals : we extracted records of patients aged 18 years resident in apulia discharged with a diagnosis of t1 dm ( icd9 - cm codes 250 . x1 and 250 . x3 ) as either main or secondary diagnosis for the period 20042013 . user fee exempt registry ( ufer ) , in which information on chronic patients entitled to fee exemption for medical consultations and drugs for their specific medical condition was collected : each condition was identified by a specific and unique code . we extracted records of subjects aged 18 years resident in apulia entitled to fee exemption for diabetes ( ufer code : 013 ) in 2013 , regardless of the date of the first diagnosis.drugs prescription registry ( dpr ) , where information on drugs prescribed to patients by the health services was recorded : drugs were coded using the anatomical therapeutic chemical classification ( atc ) . we extracted records of subjects aged 18 years resident in apulia with a presumed first drugs prescription for insulin or analogues ( atc code : a10a ) in the period 20042013 . hospital discharge registry ( hdr ) , which collects data on discharge diagnoses ( one main and up to five secondary diagnoses ) and procedures of all patients admitted to hospitals : we extracted records of patients aged 18 years resident in apulia discharged with a diagnosis of t1 dm ( icd9 - cm codes 250 . x1 and 250 . x3 ) as either main or secondary diagnosis for the period 20042013 . user fee exempt registry ( ufer ) , in which information on chronic patients entitled to fee exemption for medical consultations and drugs for their specific medical condition was collected : each condition was identified by a specific and unique code . we extracted records of subjects aged 18 years resident in apulia entitled to fee exemption for diabetes ( ufer code : 013 ) in 2013 , regardless of the date of the first diagnosis . drugs prescription registry ( dpr ) , where information on drugs prescribed to patients by the health services was recorded : drugs were coded using the anatomical therapeutic chemical classification ( atc ) . we extracted records of subjects aged 18 years resident in apulia with a presumed first drugs prescription for insulin or analogues ( atc code : a10a ) in the period 20042013 . we calculated the annual standardized hospitalization rates ( number of hospitalizations / number of residents per 1,000 italian populations ) in the period 20092013 . the mid - year estimates of apulian and italian populations were obtained from istat ( italy 's national census bureau ) estimate . in order to estimate t1 dm incidence in the period 20092013 , we created a unique database ( ud ) matching the records extracted from the three data sources by using personal i d number as linkage key ( figure 1 ) . in order to ensure that only new t1 dm diagnoses were extracted , we performed a retrospective data cleansing by comparing data from the period 20092013 with that from 20042008 ; we identified duplicates by using the personal i d number as linkage key . annual crude and specific , by sex and group of age , incidence rates were calculated by dividing the ud cases by the number of residents in apulia for the period 20092013 . in order to assess the effects of age , gender , and calendar year , a poisson regression model was performed by using stata se 14.1 , considering p values of 0.05 as significant . moreover , the completeness of each source ( sensitivity ) was estimated by dividing the number of t1 dm cases observed in each source by the total number of patients in the ud . the rcod is currently fed by a network of 13 paediatricians working in nine out of the 30 regional paediatric departments and one endocrinologist who works in one of the seven departments of endocrinology . a case of diabetes mellituswas defined using the following criteria : symptoms of marked hyperglycaemia including polyuria , polydipsia , weight loss , sometimes with polyphagia , and blurred vision . a1c 6.5 % or fasting plasma glucose ( fpg ) 126 mg / dl ( 7.0 mmol / l ) where fasting is defined as no caloric intake for at least 8 h or 2 h plasma glucose 200 mg / dl ( 11.1 mmol / l ) during an oral glucose tolerance test ( ogtt ) : the test was performed as described by the who , using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water or in a patient with classic symptoms of hyperglycaemia or hyperglycaemic crisis , a random plasma glucose 200 mg / dl ( 11.1 mmol / l ) . insulin dependence and positivity for autoantibodies that are common in t1dm : islet cell antibody ( ica ) , glutamic acid decarboxylase ( gad65 ) autoantibody , insulin autoantibody ( iaa ) , islet antigen 2 ( ia - 2 ) autoantibody , zinc transporter 8 ( znt8 ) autoantibody . data are recorded by using an online data entry platform available by password authentication on the institutional website of the regional observatory for epidemiology . symptoms of marked hyperglycaemia including polyuria , polydipsia , weight loss , sometimes with polyphagia , and blurred vision . a1c 6.5 % or fasting plasma glucose ( fpg ) 126 mg / dl ( 7.0 mmol / l ) where fasting is defined as no caloric intake for at least 8 h or 2 h plasma glucose 200 mg / dl ( 11.1 mmol / l ) during an oral glucose tolerance test ( ogtt ) : the test was performed as described by the who , using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water or in a patient with classic symptoms of hyperglycaemia or hyperglycaemic crisis , a random plasma glucose 200 mg / dl ( 11.1 mmol / l ) . insulin dependence and positivity for autoantibodies that are common in t1 dm : islet cell antibody ( ica ) , glutamic acid decarboxylase ( gad65 ) autoantibody , insulin autoantibody ( iaa ) , islet antigen 2 ( ia - 2 ) autoantibody , zinc transporter 8 ( znt8 ) autoantibody . islet cell antibody ( ica ) , glutamic acid decarboxylase ( gad65 ) autoantibody , insulin autoantibody ( iaa ) , islet antigen 2 ( ia - 2 ) autoantibody , zinc transporter 8 ( znt8 ) autoantibody . the main information collected in the rcod is physician contact details , demographic characteristics of the patient ( including personal i d number ) , date of first diagnosis , department and hospital of diagnosis , values of ph , positivity for ica , gad65 autoantibody , iaa , ia - 2 autoantibody , znt8 autoantibody , comorbidities , family history , and date of record creation . in order to assess the sensitivity of the rcod , we extracted all cases of t1 dm registered in the period 20092013 and we matched them with the ud by using the personal i d number as linkage key . we also assessed the level of completeness of each variable collected in the rcod and the timeliness of registration by calculating the average time between the date of first diagnosis and the date of record creation . the study was approved by the institutional review board of the apulian observatory for epidemiology . it was conducted in accordance with the guidelines for good clinical practice and the ethical principles originating in the declaration of helsinki . between 2009 and 2013 , in apulia , we identified a total of 4,642 hospitalizations for diabetes mellitus in subjects aged 18 years , of which 4,255 for t1 dm , with an average of 851 admissions / year and an annual standardized hospitalization rate of 1.2 per 1,000 . after cleansing of duplicates , we identified 547 patients who had been discharged with a primary diagnosis of probable t1 dm . a total of 590 subjects 18 years old entitled to fee exemption for diabetes were recorded in 2013 . drugs prescriptions for insulin or analogues recorded were 40,195 ( annual average : 8,039 ) , accounting for a total of 722 ( annual average : 144 ) subjects aged 18 years with a presumed first prescription between 2009 and 2013 . in the study period , a total of 917 cases ( about 184 / year ) were recorded in at least one of the three sources . the estimated average annual incidence rate was 25.2 per 100,000 ( 25.7 per 100,000 males and 24.4 per 100,000 females , resp . ) and progressively decreased in the study period ( p 0.05 ; tables 1 and 2 ) . it was lower in children aged 1 year , increased with age , and peaked in children aged from 5 to 9 years ( p 0.05 ; tables 1 and 2 ) . the contribution of each data source to the ud is showed in figure 2 .48.4 % of patients were identified in all three sources , 5.9 % in two of the three sources ( hdr / ufer or hdr / dpr or dpr / ufer ) , and 45.7 % in one source ( hdr or ufer or dpr ) . the sensitivity of dpr was 78.7 % , higher than that of ufer ( 64.3 % ) and of hdr ( 59.6 % ) . during 20092013 ,360 new cases of t1 dm were recorded in the rcod ( 50.8 % males ) with an average age at diagnosis of 8.6 years ( sd = 4.1 ; range 017 years ) . most cases were aged between 5 and 9 years ( 38.6 % ; n = 139 ) and 1014 years ( 34.2 % ; n = 123 ) , 18.3 % ( n = 66 ) were 14 years old , and 8.3 % ( n = 30 ) were 1517 years old ; only two cases were 2 years ( 0.5 % ) .11.1 % ( n = 40 ) of patients ' relatives had a diagnosis for t1 dm , 13.9 % ( n = 50 ) for t2 dm , 7.5 % ( n = 27 ) for thyroid disease , 1.7 % ( n = 6 ) for rheumatoid arthritis , and 3.6 % ( n = 13 ) for celiac disease .8 % ( n = 29 ) of enrolled patients were also affected by celiac disease , 7.5 % ( n = 27 ) were affected by thyroiditis ,0.8 % ( n = 3 ) were obese , and two suffered from arnold chiari syndrome type i. 16.7 % ( n = 18/108 ) of cases tested positive for ica , 69.8 % ( n = 164/235 ) for gad65 autoantibody , 49.5 % ( n = 102/206 ) for iaa , 53.6 % ( n = 15/28 ) for ia - 2 autoantibody , and 33.3 % ( n = 1/3 ) for znt8 autoantibody . after record linkage between the rcod and the ud , we identified a total of 922 patients aged 18 years . the average sensitivity of the rcod was 39.05 % ( 360/922 ; 95 % ci : 34.01 % 44.09 % ) . the rcod missed a total of 562 patients ( mean age = 10.34.9 years , 52.8 % males ) of which 35.2 % ( 198/562 ) were hospitalized , 43.8 % ( 246/562 ) were entitled to fee exemption for diabetes , and 66.4 % ( 373/562 ) had drugs prescriptions for insulin or analogues . the level of completeness was 90 % for all the rcod variables with the exception of ph , with an estimated average annual incidence rate of 25.2 per 100,000 inhabitants , apulia appeared as a high - incidence region . this is in contrast with previous studies reporting that the lowest t1 dm rates in italy were observed in the southern regions . lower incidence rates were recorded in lombardy ( 7.2 / 100,000 per year ) and marche ( 9.7 / 100,000 per year ) regions during the diamond project conducted from 1990 to 1994 in children 14 years of age and the ridi study ( 12.26 per 100,000 person - years in the period 19902003 among children 014 years old ) . worldwide , the highest rates were found in sardinia , italy ( 38.8 / 100,000 per year ) , and in some european nordic countries ( finland , sweden , and norway ) . whether differences in incidence of type 1 diabetes in italy could be attributed to genetic differences and to an increase in the prevalence of susceptible genes , due to improved survival , or to a different distribution of nongenetic factors and environmental determinants of the disease , such as infections , nutritional components , and toxins , remains to be clarified . compared with other studies , we found a higher , though not statistically significant , incidence rate in boys rather than in girls . regarding the age effect , we found a high incidence in infants , in contrast with some previous studies where development of t1 dm in the first years of life was considered very rare but in accordance with the global increase in the incidence in very young children . in contrast to the trends recorded in most populations worldwide from 1989 to 2003 , in apulia the incidence rate seemed to reduce over time ( from 36.6 in 2009 to 20.2 in 2013 ) . however , these results should be interpreted with caution because the period covered in our analysis was too short to accumulate enough cases for appropriate evaluations . in the period 20092013 , in apulia region , we selected from three sources ( hdr , ufer , and dpr ) 917 cases of t1 dm , of which 355 were identified as new cases by matching with the rcod . as shown in other studies , administrative health data are an efficient tool to assess epidemiologic trends in the population and a good source of population - based information for research about disease and for public health surveillance . the combination of sources in our study was fairly original when compared to the other experiences cited in the literature . an italian study by ballotari et al . showed that several data sources made a meaningful contribution to assess the burden of diabetes ( hdr , ufer , dpr , biochemistry lab , outpatient clinics , and mortality database ) , capturing cases not otherwise identified . this could explain why the incidence rate in children aged 04 years was higher in our analysis than in previous studies that estimated incidence by using only hdr ( 13.4100,000 in italy , 8.9100,000 in apulia ) . according to our findings , the dpr sensitivity estimated by ballotari et al . suggested that dpr could be considered the gold standard for monitoring the incidence of t1 dm due to its feasibility , reliability , and cost - effectiveness . as a matter of fact , all individuals with type 1 diabetes should receive insulin , and it is quite impossible to do so in italy without having been visited and having received a prescription by a paediatrician or a general practitioner . however , administrative data was not originally intended to epidemiological purpose and there could be several limitations in their use for the evaluation of the incidence of the disease , including errors at each step of the coding process . another limitation of our study was related to the different probability of a case being included on each source , making it inappropriate to adopt the capture - recapture methodology as a means to monitor the diabetes epidemic . in apulia , the probability to be hospitalized is higher among severe cases than the others ; it is not comparable to that of taking drugs ( all individuals should receive insulin ) or that of being entitled to a fee exemption . in accordance with larger national and international experiences , the apulian rcod implemented in 2009 allowed the identification , based on a clinical diagnosis , of new cases of t1 dm in patients aged 18 years , not present in the routine data sources . in our experience , only five cases were identified through rcod , most probably not hospitalized and not entitled to fee exemption for chronic medical condition in 2013 . as highlighted by a study of hodgson et al . in the uk , despite the fact that hdr represents a useful instrument in exploring the epidemiology of diabetes , it is crucial to establish dedicated diabetes registries . a diabetes registry could incorporate additional data for undertaking etiological research into this important childhood condition . although the apulian rcod has shown a level of clinical documentation completeness 90 % , a sensitivity of 39 % is still low to ensure reliable epidemiological data , firstly because of the limited number of physicians involved in the activities . since the rcod makes the collection of useful information for clinical management and follow - up of t1 dm patients possible , the active involvement of all physicians working in apulian paediatric diabetes clinics would be desirable . periodical feedback of epidemiological reports from the rcod might help increase physicians ' awareness and participation in the network .\noutput:\n" }, { "from": "agent", "value": "background . surveillance represents a key strategy to control type 1 diabetes mellitus ( t1 dm ) . in italy , national data are missing . this study aimed at evaluating the incidence of t1 dm in subjects < 18 year olds in apulia ( a large southeastern region , about 4,000,000 inhabitants ) and assessing the sensitivity of the regional registry of childhood - onset diabetes ( rcod ) in the 20092013 period . methods . we performed a retrospective study matching records from regional hospital discharge registry ( hdr ) , user fee exempt registry ( ufer ) , and drugs prescription registry ( dpr ) and calculated t1 dm incidence ; completeness of each data source was also estimated . in order to assess the rcod sensitivity we compared cases from the registry to those extracted from hdr - ufer - dpr matching . results . during 20092013 , a total of 917 cases ( about 184 / year ) in at least one of the three sources and an annual incidence of 25.2 per 100,000 were recorded , lower in infant , increasing with age and peaked in 5 - to 9 - year - olds . the completeness of dpr was 78.7 % , higher than that of ufer ( 64.3 % ) and of hdr ( 59.6 % ) . the rcod 's sensitivity was 39.05 % ( 360/922 ; 95 % ci : 34.01 % 44.09 % ) . conclusions . apulia appeared as a high - incidence region . a full , active involvement of physicians working in paediatric diabetes clinics would be desirable to improve the rcod performance ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: ankylosing spondylitis ( as ) which is also known as marie - strumpell disease , is a chronic inflammatory disorder which primarily affects axial skeleton , although peripheral joint involvement can also occur . different parts of joints affected are synovial , cartilaginous articulations , and the sites of attachment of tendon and ligament to bone . involvement of tmj causes pain restrictive movement of joint that cause inability to eat . although conventional radiography can pick up tmj involvement , but computer tomography ( ct ) is required for joint space relations and bony morphology . here , we are reporting a case of as with tmj involvement and highlights the importance of imaging in this disease , as early diagnosis and treatment can improve the quality of life in these patients . a 35 - year - old male , follow - up of a case of as diagnosed 5 years back on regular treatment with sulfasalazine , reported to the medicine outpatient department with a history of restricted movement of mouth opening and morning stiffness of jaw for 3 months which was associated with pain and morning stiffness . investigations showed erythrocyte sedimentation rate 70 mm , c - reactive protein 35 , and positive human leukocyte antigen - b27 . x - ray lumbosacral spine showed ossification within the facet joint capsules , and ligamentum flavum bilaterally produces two vertical linear densities ( upper black arrows ) at the lateral aspects of the vertebral bodies . there is coexistent ossification within the interspinous - supraspinous ligaments , creating the midline linear opacity ( starred ) known as dagger sign . furthermore , noted is the complete obliteration of bilateral sacroiliac joint spaces ( white arrows ) suggestive of bony ankylosis [ figure 1 ] . volume rendered ct images of tmj revealed complete bony ankylosis of the left tmj [ figure 3 ] . diagnosis of as with tmj involvement was made and the patient was treated by a combination of conservative techniques that includes including rest , exercises for painful joint , and pharmacological treatment with sulfasalazine 1 g twice daily and indomethacin 50 mg daily . his clinical signs and symptomsthe patient was advised biological therapy for as disease activity and later on he was counselled for splint or prosthosis , both of which he refused . x - ray lumbosacral spine showing ossification within the facet joint capsules and ligamentum flavum bilaterally produce two vertical linear densities ( upper black arrows ) at the lateral aspects of the vertebral bodies . there is co - existent ossification within the interspinous - supraspinous ligaments , creating the midline linear opacity ( starred ) known as dagger sign . furthermore , noted is the complete obliteration of bilateral sacroiliac joint spaces ( white arrows ) suggestive of bony ankylosis orthopantomogram showing loss of joint space in bilateral temporomandibular joints volume rendered computer tomography images of temporomandibular joint revealing complete bony ankylosis of the left temporomandibular jointdavidson et al . reported that the restricted mouth opening in the patients with as may be due to the proximity of the chin to the neck . some authors also reported that difficulty in opening the mouth may be due to the flattening and erosions of the mandibular condyle . found that the limitation of jaw mobility in such patients might also be caused by an elongation of the mandibular coronoid process . had reported that patients experience pain , stiffness , headache , and restricted movements in tmj . wenneberg and kopp in 1982 reported that 13 % of patients has restricted mouth opening , and 31 % had tenderness of the tmjs compared with control group ( with 4 % having restricted mouth opening and 1 % having preauricular tenderness ) . our patient , a case of as on regular treatment , developed pain , stiffness , and restricted mouth opening was evaluated . patient was managed conservatively for a month . however , as there was no improvement , the patient was advised biological therapy for as disease activity and later on he was counselled for splint or prosthosis , both of which he refused . first , there could be destruction of the capsular or disc attachment which can result in internal derangement and degenerative joint diseases . second , there could be a primary synovitis with direct breakdown of the articular surfaces . in such a case , internal derangement would result from articular surface changes and not precede them . treatment of tmj involvement in as includes nonsteroidal anti - inflammatory drugs ( nsaids ) . patients refractory to nsaids are treated with drugs as , corticosteroid , disease - modifying antirheumatic drugs , and biologicals . in patients with a painful , reduced mouth opening capacity , the treatment of malfunctions using biofeedback and splint therapy as well as restorative and / or prosthetic rehabilitation is advised . however , patients with as can also have tmj involvement . clinicians should examine the tmj as well while examining a patient of as .\noutput:\n" }, { "from": "agent", "value": "ankylosing spondylitis ( as ) is a chronic systemic inflammatory disorder . it primarily affects the axial skeleton through involvement of the peripheral joint scan occurs . temporomandibular joint ( tmj ) involvement in as varies from 4 % to 35 % . here , we present a case of a 35 - year - old male , follow - up of as from last 8 years on nonsteroidal anti - inflammatory drugs , presented with fresh complaints of painfully restricted movements of jaw during swallowing . computer tomography of patient demonstrates articular cartilage changes with disc and joint abnormalities ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: electrical stimulation is a popular treatment used by physiotherapists for muscle strengthening , endurance , spasticity management , pain control , circulation promotion and edema control1 ,2,3,4,5 . transcutaneous electrical nerve stimulation ( tens ) and interferential current ( ifc ) are widely used for relief of chronic and acute pain6 ,7,8,9 . tens machines are usually relatively inexpensive , portable , battery operated devices , while ifc machines tend to be more expensive , are not portable , and require an electrical power source10 . experimental pain models provide a useful representation of clinical pain and make it possible to control variables such as pain intensity and duration . clinical trials can be expensive and time consuming , while the intensity , location , and duration of clinical pain can be difficult to control . experimental pain models can thus guide subsequent clinical trials , potentially saving time and money . different experimental pain models exist utilizing different types of pain stimulus such as cold , mechanical , electrical , and ischemic pain11 . the frequencies of 50 hz and 100 hz have a high analgesic effect12 ,13,14,15 . experimental pain models using the same frequencies for tens and ict analgesic effects have been compared , but the analgesic effects are unclear16 ,17,18 . thus far , there have been few studies that have compare the analgesic effects of tens and ifc with these two frequencies . the ischemic pain model is a method commonly used to validate analgesic effect . the modified version of the submaximum effort tourniquet technique ( sett ) can cause pain that is similar to clinical pain10 , 19 . therefore , this study used the ischemic pain model to compare the analgesic effects of 50 hz tens , 50 hz ifc , 100 hz tens and 100 hz ifc . the subjects were 36 university student volunteers ( 18 male , 18 female ) without known pathology . their mean age was 24.5 years ( sd 2.2 ) ( table 1table 1 . general characteristics of the subjectsvariablemeansdage ( yr ) 24.52.2 height ( cm ) 170.312.5 weight ( kg ) 64.715.3 sd , standard deviation ) . all subjects who expressed interest in participating in the study were briefed on the experimental procedure ( both verbally and in written form ) and were screened for contraindications to the experimental procedure or electrotherapy . these contraindications included any illness or pathology such as peripheral vascular abnormalities , hypertension , hypotension , peripheral neuropathies , recent trauma , and menstruation problems . subjects who were taking any medication or who were likely to take any medication during the period of study were excluded . sd , standard deviation the investigator also checked each subject s nondominant arm for signs of previous trauma and recorded the subject s blood pressure from the nondominant arm ( because the effectiveness of tens and ifc is dependent on normally functioning nerves in the skin ) using a sphygmomanometer . outcome measurements were recorded from the nondominant arm so that subjects could use the dominant arm when completing visual analog scales ( vass ) . all subjects who expressed an interest in the study met the criteria and agreed to participate . subjects were required to sign a consent form and were reminded that they had the right to withdraw from the experiment at any time . all subjects gave informed consent according to the methods outlined by sahmyook university s institutional review board . this study protocol and procedures were also approved by sahmyook university s ethics committees . each subject attended our research laboratory on four separate occasions with a 24 - , 48 - , or 72 - to 96 - hour interval between visits . during each visit , self - reported pain intensity was recorded at 1 - minute intervals during the ischemic pain test using a vas in which 0 cm represented no pain and 10 cm represented worst pain imaginable . analgesia was induced by one of four treatments : 50 hz tens , 50 hz ifc , 100 hz tens or 100 hz ifc . at the end of the fourth testing session , participants were asked , which of the two modalities , if either , seemed more effective ? and which of the two modalities , if either , felt more comfortable ? a sphygmomanometer cuff is usually applied above the subject s elbow and inflated to 200 mm hg . during pilot studies in our laboratory , we found that most subjects experienced widespread paresthesia in the arm rather than pain . thus , we modified the sett by applying the sphygmomanometer cuff to the forearm 5 cm below the elbow crease , because this placement of the sphygmomanometer cuff produced a dull aching pain that was localized to the area of the cuff in all subjects . before the start of the experiment , maximal grip force was determined using a dynamometer ( martin vigorimeter * ) fitted with a medium bulb . seventy - five percent of the maximal grip force was calculated and identified on the dynamometer scale . subjects raised their nondominant arm vertically above their head for 1 minute to decrease the volume of blood the limb . the sphygmomanometer cuff ( 15 cm in length ) was then inflated to above 200 mmhg at a rate of 40 mmhg per second . full cuff inflation was taken as time 0 , and subjects rated the intensity of pain in their raised arm using the vas . the forearm was then returned to rest in the horizontal position on a polystyrene box that was designed to support the forearm and hand without applying pressure to the sphygmomanometer cuff . subjects then performed 20 hand - gripping exercises at 75 % of their maximal grip force for a period of one minute ( squeeze for two seconds and rest for two seconds ) . pain intensity was recorded on completion of these exercises and at one minute intervals for the remainder of the experiment . the cuff was deflated over a period of two minutes to allow the volume of blood to increase in the limb , and the final pain intensity rating was taken one minute after cuff deflation . no signs of trauma were observed in the arms of any subjects following the ischemic pain test10 , 19 . on each visit to the laboratory , subjects were randomly allocated to one of four treatments : 50 hz tens , 50 hz ifc , 100 hz tens and 100 hz ifc . a single - blind experimental approach was used whereby the subjects were not aware of which treatment they were being given . four self - adhesive electrodes ( each electrode 4.5 cm ) were applied before the start of the experiment , and treatment was switched on 10 minutes and 40 seconds before the arm was raised above the head . we were concerned that afferents under the cuff might be unable to fire due to pressure block from the cuff . however , all subjects reported that they experienced a strong but comfortable electrical paresthesia , suggesting to us that afferents remained active . electrodes were applied in a quadripolar manner to the anterior and posterior aspects of each subjects forearm so that electrical currents would intersect at the midpoint of the cuff . the distal electrode for channel a was attached to the anterior surface of the forearm 5 cm proximal to the first wrist crease . the distal electrode for channel b was attached to the posterior surface of the forearm directly beneath the distal electrode for channel a. proximal electrodes were applied directly above the cuff . subjects in the ifc group were told that to produce an effect , the intensity of the stimulator must be maintained at a strong but comfortable level at all times . initially , when the ifc device was switched on for the first time , thecomfortable level was obtained by increasing the current amplitude so that the subjects reported either that the currents were uncomfortable or that the motor threshold had been reached . high analgesic effects of bursts at 50 hz and 100 hz generated by 4 - khz sinusoidal waves were applied20 , 21 . the tens in our study was delivered via four electrodes using a dual - channel device in order to standardize the amount of current administered by the two modalities . electrodes were applied to the anterior and posterior aspects of the each subjects s forearm in an identical manner to that for ifc . to minimize interference of currents from the two channels , both distal electrodes were attached to channel a of the tens device , and both proximal electrodes were attached to channel b. the comfortable level was obtained using the same procedure as that described for ifc . the high analgesic effect of a 125 - microsecond phase duration at a frequency of 50 hz and a 200 - microsecond phase duration at a frequency of 100 hz were applied20 , 21 . data were analyzed by calculating the change in pain intensity rating during the treatment between measurements . treatment effects were determined by a two - way repeated measures analysis of variance ( anova ) of the change in pain intensity during treatment for vas ratings 4 through 9 and all vas ratings . after completing the four interventions , there were significant effects for time , which were attributed to a significant reduction in pain intensity during treatment , for vas ratings 4 through 9 and all vas ratings ( vas 112 ) ( p 0.05 ) . there were no significant effects for groups or group - time interaction in pain intensity during treatment for vas ratings 4 through 9 and all vas ratings . there were significant time effects that could be attributed to the increase in pain intensity in all groups during cuff inflation and hand - grip exercises ( vas 13 ) and a decrease in pain intensity immediately upon cuff deflation ( vas 1012 ) . this result means pain intensity was significantly increased by the treatment in all groups ( p 0.05 ) . but there was no significant difference between the groups ( table 2table 2 . pain intensity rating for treatments during the ischemic pain testcuffinflatedhandgripexercisestarthandgripexerciseendcuff inflatedcuffdeflatingcuffdeflatingcuffdeflated - 20 svas 10 minvas 21 minvas 32 minvas 43 minvas 54 minvas 65 minvas 76 minvas 87 minvas 98 minvas 109 minvas 1110 minvas 1250 hz tensmeansd0 .40.81.51.22.41.82.81.63.41.64.01.64.11.74.51.84.81.95.12.22.62.31.32.050 hz ifcmeansd0 .50.61.30.62.11.22.41.23.01.33.61.93.92.14.22.24.52.44.32.62.52.51.62.3100 hz tensmeansd0 .30.31.30.52.20.92.51.12.91.43.61.53.71.33.91.44.11.63.91.92.21.81.41.2100 hz ifcmeansd0 .40.41.10.61.90.82.21.02.81.53.41.73.61.54.01.54.41.44.12.02.31.71.71.1 values are expressed as the mean sd . tens , transcutaneous electrical nerve stimulation ; ifc , interferential currents ; vas , visual analog scale ) . tens , transcutaneous electrical nerve stimulation ; ifc , interferential currents ; vas , visual analog scale at the end of the fourth session , participants were asked which of the four types of intervention felt most comfortable . twenty subjects ( 56 % ) reported that 50 hz ifc was the most comfortable , six ( 17 % ) felt that 100 hz - ifc was the most comfortable , six ( 17 % ) felt that 50 hz tens was the most comfortable , and four ( 10 % ) felt that 100 hz tens was the most comfortable . at the end of the second session , nineteen subjects ( 53 % ) reported that 50 hz ifc was the most effective , nine ( 25 % ) felt that 100 hz ifc was the most effective , five ( 14 % ) felt that 50 hz tens was the most effective , and three ( 8 % ) felt that 100 hz tens was the most effective . the effects of tens and ifc stimulation at frequencies of 50 hz and 100 hz on pain relief were analyzed to investigate the usefulness of electrical stimulation on ischemic - induced pain . in this study , johnson and tabasam used 100 - hz stimulation and found a greater effect with tens than ifc in a cold pain model , but the difference between treatments was not significant . the measured difference was not statistically significant , but the study only had seven participants in each , group so the lack of significance could have been due to low statistical power22 . with methods similar to this study , shanahan et al . they found that tens at a frequency of 100 hz had a greater analgesic effect than premodulated ifc at a beat frequency of 100 hz . the balance of evidence thus indicates that ifc is less effective than tens . cheing and hui - chan reported no significant difference between treatments in a heat pain model23 . johnson and tabasam reported no significant difference between treatments in an ischemic pain model20 . johnson and tabasam reported a statistically significant result , with 100 hz tens being more effective than premodulated 100 hz ifc23 . remarked that the controversy over the effect of pain relief between tens and ifc resulted from lack of statistical power in published papers due to inadequate sample sizes21 . found that the effects of tens and ifc at 50 hz on the pain threshold was significantly increased and that there was no significant difference between tens and ifc in a cold pain model21 . johnson et al . found that higher frequencies of pulsed current ( above 50 hz ) resulted in a lesser hypoalgesic effect17 . the between - frequency differences in the study by johnson et al . were not statistically significant , possibly due to a small sample size , but a downward trend was clearly evident above 40 hz17 . speculated that a short burst duration prevents or severely restricts multiple firing of sensory nerve fibers and instead produces one action potential per burst21 . thus 50 hz ifc and 50 hz tens are equally effective in alleviating cold - induced pain in healthy subjects21 . therefore , in previous studies , there was a debate that not significant difference between the different types of electrical stimulation . the results of our study were similar to those of previous studies and also showed a statistically significant difference between the different types of electrical stimulation , but analgesia was significantly increased during electrical stimulation in all groups . reported that subjects experienced the most analgesia from electrical stimulation and the greatest comfort at a frequency of 50 hz with ifc , as was the case in our study21 . the current results and previous tens and ifc comparative studies strengthen the conclusion drawn that low - duty - cycle , burst - modulated ac is more comfortable than conventional low - frequency pulsed current21 . that 50 hz ifc is an acceptable treatment is likely a consequence of the lesser discomfort . we conclude that there were no differences in the analgesic effects of the four interventions under the present experimental conditions . however , 50 hz ifc is more comfortable than other interventions and is likely to be better accepted and tolerated by patients .\noutput:\n" }, { "from": "agent", "value": "[ purpose ] this study compared the analgesic effects of transcutaneous electrical nerve stimulation ( tens ) and interferential currents ( ifc ) on induced ischemic pain in healthy volunteers . [ subjects ] the subjects were 36 volunteers ( 18 male , 18 female ) without known pathology that could cause pain . their mean age was 24.52.2 years . [ methods ] a single - blind and parallel - group method was used . subjects were randomly allocated to receive each 50 hz tens , 50 hz ifc , 100 hz tens , and 100 hz ifc . this study experimentally induced ischemic pain in otherwise pain - free subjects using a modified version of the submaximal effort tourniquet technique . subjects completed twelve cycles of the ischemic - induced pain test . the primary outcome measure was the change in self - reported of pain intensity during one of four possible treatments . [ results ] there were significant effects for time , which were attributed to a significant reduction in pain intensity for all groups . there were no significant effects for groups or group - time interaction . the 50 hz ifc treatment was more comfortable than the other treatments in the present study , and it is likely to be better accepted and tolerated by patients . [ conclusion ] we conclude that there were no differences in the analgesic effects of the four treatments under the present experimental conditions . the 50 hz ifc treatment is more comfortable than the other treatments ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: glycocalyx is composed of glycoconjugates such as glycoproteins , glycolipids , and proteoglycans . in mammals , the glycoproteins of testicular germ cells are important in the sperm differentiation and interactions with sertoli cells during spermatogenesis . glycocalyx also plays an important role in sperm protection against the female immune system , acrosome reaction , and ability of the sperm to fertilize oocytes . some cases of male infertility may be in consequence of changes in the sperm surface glycoconjugates . in mammals such as humans , the sperms that leave the testis are infertile andsome biochemical changes are needed to fertilize the sperms in the reproductive system of males and females . purohit et al . in 2008 showed that the reaction to wheat germ agglutinin ( wga ) of the sperms extracted from oligozoospermic cases was diminished . glcnac , as a permanent part of the sperm membrane , is an n - glycan and contributes to the physiochemical properties of the membrane . n - glycans confer extraordinary flexibility to the membrane , which is vitally important for motility . lectins are employed as an excellent tool for examining glycoconjugate changes in mammalian cells during development , cell differentiation , and maturation . lectin histochemistry studies have shown that all cell types of spermatogenesis lineage contain mannose , n - acetylglucosamine , sialic acid , galactose , and n - acetylgalactosamine in human , and mouse . the presence of glycoconjugates , including those recognized by lectins such as concanavalin a ( con a ) , wga , and peanut agglutinin ( pna ) , from the testicular to the ejaculated sperm membrane , has been previously studied . the modification of the glycoproteins of the sperm surface is one of the aspects of sperm maturation , which occurs in the epididymis and is correlated with many sperm functions . it has been shown that whereas some glycoconjugate - reacted lectins such as con a and pna induce acrosome reaction , wga does not . in assisted reproductive technology ( art ) , one of the most important considerations is the production of excessive free radicals , including reactive oxygen species ( ros ) , due to laboratory manipulations , cellular waste products , presence of large numbers of leukocytes , and immature germ cells . therefore , sperm samples from males undergoing art programs have been subjected to oxidative stress and are susceptible to oxidative damage , especially when the samples are exposed to low levels of protective antioxidant . research has shown that ros impacts on cellular components such as lipid and protein and the carbohydrate components , of the cell membrane . immature sperms such as sperms extracted from the testis ( tese ) produce much more ros than ejaculated mature sperms . sperm stimulators such as pentoxifylline ( pf ) and l - carnitine ( lc ) are ros scavengers . the epididymis produces many chemicals such as lc , the concentration of which in the epididymis is twice that present in the testis in rats . lc plays an important role in the onset of sperm motility and sperm maturation and it subsequently increases sperm fertility . it has been suggested that high concentrations of carnitine in the epididymal fluid serve to stabilize the sperm plasma membrane , confer a beneficial effect on cell survival , and reduce the number of acrosome - reacted sperms . the current literature suggests that a large number of agents such as pf improve sperm quality ; however , any supplementation may exert both positive and negative effects on the various aspects of sperm functions . for instance , antioxidants such as pf act as a stimulator of the sperm , and can protect the sperm plasma membrane integrity . pf also has a protective effect on the reduction of the occurrence of acrosome reaction during the freeze - thaw process . in patients with oligoasthenozoospermia , treatment of pre - frozen sperms with pf is thought to improve induced acrosome reaction . however , pf is toxic and leads to a reduction in sperm survival if administered for longer than 90 minutes . with regard to the detrimental effects of free radicals on the structural integrity of membrane glycoconjugates and sperm function , we sought to use a non - toxic antioxidant to reduce oxidative stress . pf is a toxic antioxidant , while lc is a non - toxic antioxidant supposed to preserve the glycoconjugate content of the sperm . therefore , it is postulated that adding lc could yield an intact sperm with a normal glycoconjugate pattern . the present study was designed to investigate the effects of lc and pf on the glycoconjugate content in the testicular sperm membrane in vitro . we made use of three lectins : pna to detect acrosome intact sperms ; wga to detect non - capacitated sperms ; and con a to detect acrosome - reacted cells . forty - eight male balb / c mice , weighing 25 - 30 grams , were acclimatized to the laboratory condition ( 12 hours of light and 12 hours of darkness at a temperature of 22 - 24c ) . the animal experiments were approved by the ethics committee of shiraz university of medical sciences . fluorescein isothiocynate ( fitc ) - conjugated lectins ( sigma , usa ) , including pna , con a , and wga , were used to detect n - acetylgalactosamine / galactose , mannose , and sialic acid , respectively . the testes were washed with saline and ham s f10 ( sigma , usa ) . under a stereo microscope , the tunica albuginea was separated from the testes , and seminiferous tubules were scattered by two syringes gently . in order to separate red blood cells , ham s f10 was added to the samples and centrifuged at 500 rpm for 10 minutes . the palette was transferred to a petri dish , containing ham s f10 , and cut into pieces . the sample was , thereafter , vortexed for one minute to extract the sperms from the tubules . the sample was allowed to remain for one hour at room temperature before it was centrifuged at 500 rpm for 10 minutes . the leydig and sertoli cells were placed on the bottom , and the supernatant contained sperms . equal volumes of ham s f10 and ham s f10 containing 3.6 mm of lc ( sigma , usa ) or pf ( sigma , usa ) were added to the aliquoted sperm samples . therefore , the final concentration of 1.76 mm of lc or pf was obtained . sperm motility assay sperm motility was assessed 30 and 90 minutes after incubation at room temperature . all the motility assessments were performed according to the world health organization ( who ) guidelines . to evaluate sperm motility , the sperm cells were classified as immotile ( i m , no movement ) , non - progressive motile ( np , all other patterns of motility with an absence of forward progression , e.g. swimming in small circles , the flagella force hardly displacing the head , or when only a flagella beat can be observed ) , and progressively motile ( pr , spermatozoa moves actively , either linearly or in a large circle , regardless of the speed ) . the percentage of the motile sperms was calculated according to a previous work conducted by moreira et al . lectin histochemistry the smears were prepared from the aliquoted sperms . the smears were fixed with paraformaldehyde for 20 minutes and washed in phosphate buffered saline ( pbs ) for 30 minutes . then , the sperms were incubated in fitc - conjugated lectins ( 10 l / ml ) for 2 hours in the dark . the smears were , subsequently , washed in pbs and counterstained with 4,6 - diamidino -2-phenylindole ( dapi ) for 5 minutes . the specimens were observed under the fluorescent microscope ( nickon , eclipse , e600 ) . all the samples were incubated in the media , lc or pf , and were washed with 800 l of pbs and centrifuged at 1200 rpm for 10 minutes before they were fixed with 2 % paraformaldehyde for 30 minutes at 4c . , the samples were incubated in fitc - conjugated lectins ( 10 l / ml ) for 2 hours at 37c in a humidified atmosphere in the dark . they were then washed twice in pbs , and the percentage of the lectin - reactive sperms was measured via fl1 channel flow cytometry . the percentage of the spermatozoa that reacted with fitc - conjugated lectins was analyzed by histogram using winmdi 2.8 software . statistical analyses all the results are presented as meanse ( standard error of mean ) . the statistical analyses were performed using the one way analysis of variance ( anova ) and the least significant difference test ( lsd ) using spss version 15 for windows . a p value less than 0.05 was considered a statistically significant difference . sperm motility assay the data showed a significant increase in the percentage of the progressive sperms exposed to pf compared to the control sperms at 30 minutes ( p = 0.001 ) and 90 minutes ( p = 0.007 ) after incubation . there was a significant decrease in the percentage of the immotile sperms and a significant increase in the percentage of the non - progressive sperms in the presence of lc and pf compared with the control samples at 30 minutes ( p = 0.000 and p = 0.000 ) and 90 minutes after incubation ( p 0.001 and p 0.001 ) , respectively . table 1 summarizes the data for the sperm motility assay . the comparison of the testicular sperm motility percentages ( means.e ; n = 8 ) at 30 and 90 minutes after incubation in the media ( control ) , l - carnitine - and pentoxifylline * significant difference with control group ( p 0.008 ) ; significant difference with l - carnitine - treated group ( p 0.05 ) ; significant difference with l - carnitine - treated group ( p 0.009 ) lectin histochemistry distribution pattern the data demonstrated no changes in the distribution pattern of the glycoconjugates in the testicular sperms in the presence of the additives compared with the media . all the lectins reacted with acrosome : pna reacted to the middle piece and wga and con a reacted to all the parts of the testicular sperms . however , the reaction to con a was less intense in the acrosome region of the lc - and pf - treated sperms ( figure 1 ) . lectin histochemistery of the testicular sperms exposed to the media ( control ) , l - carnitine and pentoxifylline at 30 minutes . pna reacted with the middle piece , and wga and con a reacted to all the parts of the testicular sperm . scale bar is 20 m effects of lc and pf on sperm reaction to wga at 30 minutes after incubation , the lc - treated samples exhibited a significant increase in the percentage of the wga - reactive sperms compared with the control sperms ( p = 0.01 ) . at 90 minutes after incubation , there was no significant difference in the percentage of the wga - reactive sperms between the aliquoted samples ; however , a non - significant increase was observed between the percentages of the wga - reactive sperms in the two treated samples and control samples ( figure 2 and table 2 ) . comparison of wga - positive sperms after exposure to the media ( control ) , l - carnitine and pentoxifylline . a : dot plot ; b : unstained ; c : l - carnitine - exposed sample at 30 minutes ( 99.720.08 ) ( p = 0.01 ) ; d : pentoxifylline - exposed sample at 30 minutes ( 99.540.14 ) ; e : control sample at 30 minutes ( 99/080 .23 ) ; f : l - carnitine - exposed sample at 90 minutes ( 99/800 .05 ) ; g : pentoxifylline - exposed sample at 90 minutes ( 99/750 .04 ) ; h : control sample at 90 minutes ( 99/470 .21 ) after incubation the percentages of lectin - reactive sperms ( means.e ; n = 8 ) at 30 and 90 minutes after incubation in the media ( control ) , l - carnitine and pentoxifylline at 30 and 90 minutes after incubation , the mean of fluorescence intensity for wga did not show a significant difference between the experimental samples and the control sperms ( table 3 ) . the mean of fluorescence intensity ( means.e ; n = 8 ) of lectin - reactive sperms at 30 and 90 minutes after incubation in the media ( control ) , l - carnitine and pentoxifylline effects of lc and pf on sperm reaction to pna at 30 minutes after incubation , the lc - treated sperms showed a significant increase in the percentage of the pna - reactive sperms compared with the control sperms ( p = 0.02 ) . pf exhibited no change in the percentage of the pna - reactive sperms compared with the control and lc aliquots . at 90 minutes after incubation , the lc - treated samples displayed a significant rise in the percentage of the pna - reactive sperms compared with the control sperms ( p = 0.03 ) . the percentage of the pna - reactive sperms did not show a significant change in the pf - treated samples compared with the control and lc - treated sperms ( figure 3 and table 2 ) . comparison of pna - positive sperms after exposure to the media , l - carnitine and pentoxifylline . a : dot plot ; b : unstained ; c : l - carnitine - exposed sample at 30 minutes ( 94.091.4 ) ( p = 0.02 ) ; d : pentoxifylline - exposed sample at 30 minutes ( 90.241.1 ) ; e : control sample at 30 minutes ( 89/270 .5 ) ; f : l - carnitine - exposed sample at 90 minutes ( 94/571 .3 ) ( p = 0.03 ) ; g : pentoxifylline - exposed sample at 90 minutes ( 91/880 .8 ) ; h : control sample at 90 minutes ( 90/951 .1 ) after incubation at 30 and 90 minutes after incubation , the mean of fluorescence intensity for pna did not show a significant difference between the experimental samples and the control sperms ( table 3 ) . effects of lc and pf on sperm reaction to con a at 30 and 90 minutes after incubation , the data showed that the percentage of the con a - reactive sperms had a drop in the lc - and pf - treated samples compared with the control samples ; nevertheless , the difference did not constitute statistical significance ( figure 4 and table 2 ) . in the lc - treated samples , the mean of fluorescence intensity for con a displayed a significant decrease compared with the control samples at 90 minutes after incubation ( p = 0.02 ) ( table 3 ) . comparison of con a positive sperms at exposure to the media , l - carnitine and pentoxifylline . a : dot plot ; b : unstained ; c : control sample at 30 minutes ( 83.493 ) ; d : pentoxifylline - exposed sample at 30 minutes ( 74.535 ) ; e : l - carnitine - exposed sample at 30 minutes ( 74.386 ) ; f : control sample at 90 minutes ( 893 ) ; g : pentoxifylline - exposed sample at 90 minutes ( 88.643 ) ; h : l - carnitine - exposed sample at 90 minutes ( 83.215 ) after incubationaugmentation of the ability of the sperm to fertilize the oocyte is the aim of many art studies . in the testicular sperm extraction ( tese ) technique , it is important to have good quality , matured sperms for the successful application of art . our data showed that while the incubation of the samples with lc and pf conferred an increase both in testicular sperm motility and percentages of the pna - and wga - reactive sperms , it led to a decrease in the number of the con a - reactive sperms by comparison with the control group . our findings also revealed that the mean of fluorescence intensity was also decreased in the acrosome - reacted sperms in the lc - treated group compared with the control samples as indicated by the flow cytometry of the con a - reactive sperms . poor reaction to pna has been demonstrated by lectin histochemistry in human and mouse spermatogonia ; however , the reaction is known to increase in other spermatogenesis lineages as the acrosome development gradually progresses . the presence of galactose / n - acetylgalactosamine , mannose , n - acetylglucosamine , and sialic acid in testicular germ cells can also be detected by lectin histochemistry . in the present study , lectin histochemistry displayed that the administration of lc and pf did not change the distribution pattern of glycoconjugates in the sperms after 30 or 90 minutes of incubation . the ultrastructure of sperms is reported to show that the pna - binding site is situated on the outer acrosomal membrane . acrosome - reacted sperms are believed to react with con a strongly , and the ultrastructure of sperms is reported to demonstrate that the con a - binding site is situated on the inner acrosomal membrane . wga reacts more intensely to intact and non - capacitated sperms , so wga can be considered as a non - capacitated mouse sperm marker . gil - guzman , showed that the ros production occurred much more frequently in immature sperms ( tese ) than in mature ones . glycoconjugates have important roles in the interaction between sperm and zona pellucida and , subsequently , in fertilization ; therefore , any change in the membrane glycoconjugates may affect fertility . ros scavengers such as lc and pf may affect sperm metabolism , motility , and membrane . our results showed that the lc administration led to a significant rise in the number of the sperms with intact acrosomes as demonstrated by pna reaction . lc caused a significant increase in the number of the non - capacitated sperms after 30 minutes of incubation as indicated by wga reaction . as the time progressed , lc effected an increase in the number of the sperms with intact acrosomes , but no change in the number of the non - capacitated sperms was observed ; this showed that the administration of lc inhibited the early capacitation of the sperms as indicated by wga reaction . the in vivo administration of lc , as an antioxidant , can affect sperm maturation and motility , and stabilize the sperm cell membrane . the in vitro administration of lc diminishes acrosomal reaction , and thus increases the number of intact sperms , which chimes in with our results . lc is also thought to protect the sperm plasma membrane and affect carbohydrate metabolism . pf acts as an anti - oxidant , and can protect the fresh sperm plasma membrane , normal frozen - thawed sperm , and oligoasthenozoospermic patients . the protective effect of pf on the acrosome loss was also reported by esteves et al . our results also showed that pf did not impact on the incidence of capacitated or acrosome - reacted sperms . review articles have revealed a controversy vis - - vis the effects of pf on the induction of sperm capacitation and acrosomal reaction . mirshekari et al . showed no changes in the number of the capacitated canine sperm by a low dose of pf administration ; our data confirm this finding . although both lc and pf increase sperm motility , it seems that lc prevents early capacitation and acrosome loss more effectively than pf . our data showed that lc prevented early capacitation ( as indicated by wga reaction ) and subsequently inhibited acrosome reaction ( as indicated by pna and con a reaction ) . our previous work demonstrated that lc administration also improved nuclear maturation criteria more effectively than pf . pna - and wga - positive sperms indicated the intact and non - capacitated sperm populations , respectively , in the present study . whereas supplementation of the testicular sperm samples with both lc and pf enhanced sperm motility , lc was more efficient in the inhibition of sperm capacitation and acrosomal reaction as indicated by the enhancement in the percentages of wga - and pna - positive cells . our results showed that lc was more suitable than pf for utilization in the art protocol for increasing sperm integrity .\noutput:\n" }, { "from": "agent", "value": "background : the glycoconjugate content of sperms indicates their physiological and fertility properties . lectin reactivity is indicative of intact , capacitated , and acrosome - reacted sperms . in the epididymis , sperms experience maturation , glycoconjugate modification , and simultaneously , higher l - carnitine ( lc ) concentrations . the aim of this project was to evaluate the effects of lc and pentoxifylline ( pf ) on the integrity , capacitation , and acrosomal reaction of sperms by studying their lectin reactivity . methods : mouse testicular sperm samples were divided into three parts . each sample was added ham s f10 ( control ) or media containing 1.76 mm lc or pf . at 30 and 90 minutes after incubation , sperm motility was assessed . peanut agglutinin ( pna ) , wheat germ agglutinin ( wga ) , and concanavalin a ( con a ) were used to detect non - acrosome - reacted , non - capacitated , and acrosome - reacted sperms , respectively and the frequency was evaluated by flow cytometry . statistical analysis was performed using the anova . results : sperm motility increased after 30 and 90 minutes of incubation in the lc - and pf - treated cultures ( p = 0.001 ) . lc administration created a significant increase in the percentage of the non - acrosome - reacted sperms compared to the control sperms after 30 and 90 minutes ( p = 0.02 and p = 0.03 , respectively ) . the frequency of the non - capacitated sperms in the lc - treated group increased compared to the control sperms after 30 minutes significantly ( p = 0.01 ) . conclusion : although the administration of lc and pf enhanced sperm motility , lc also impacted glycoconjugates on the sperm surface . glycoconjugates are involved in the interaction between the sperm and the zona pellucida and subsequently fertilization , thereby probably influencing the male fertility state ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: combination therapy using dutasteride with an alpha blocker makes it possible to manage bph patients for a long duration . combination of the two drugs , which have different mechanisms of action against bph , may relieve lower urinary tract symptoms ( luts ) better than monotherapy with either alone . because large prostate volume may lead to severe symptomatic progression or surgical intervention , medical reduction of the prostate volume by dutasteride may change the clinical course of bph patients . the results of the the symptom management after reducing therapy ( smart - 1 ) study suggest that after reduction , monotherapy using an alpha blocker may be feasible . on the other hand , withdrawal of dutasteride is not fully understood . some patients may not be good candidates for withdrawal even though it will reduce the medical cost . thus , we performed a single - center prospective study of dutasteride withdrawal after combination therapy with an alpha blocker against bph . we performed a prospective study of bph patients who visited our hospital from 2012 to 2013 . patients who had been given alpha blockers for more than 2 months were eligible for the study . all patients underwent evaluation of the serum prostate - specific antigen ( psa ) level , prostate volume , intraprostatic architecture by transrectal ultrasound , peak urinary flow rate ( qmax ) , postvoid residual urine volume ( pvr ) , the international prostate symptom score ( ipss ) , and the overactive bladder symptom score ( oabss ) at baseline . group 1 was defined as bph with an undetectable transitional zone , group 2 as a detectable transitional zone with an unclear border , and group 3 as a transitional zone with a clear border . the ipss and oabss were evaluated every 3 months and the serum psa level , prostate volume , qmax , and pvr were evaluated every 6 months . active discontinuation of dutasteride was planned after 6 months of combination therapy with an alpha - 1 blocker . however , patients were allowed to restart dutasteride during the follow - up period according to their clinical desire . examination for adverse events such as urinary retention and symptomatic urinary tract infection was conducted at every visit to our outpatient clinic . statistical analysis was performed by using the mann - whitney u test for intergroup comparisons . the wilcoxon signed - rank test was performed to evaluate differences in parameters among treatment periods . informed consent was obtained from patients and the study was approved by the institutional review board of ntt east corporation sapporo hospital ( no . 13 - 106 ) . twenty - three patients were included in the study but only 20 completed the evaluation . mean prostate volume was 36.82 ml at baseline and the mean reduction rate was 22.1 % in the 20 patients after 6 months of combination therapy . finally , 12 patients ( 12/20 , 60 % ) restarted combination therapy in the follow - up period . although only 2 patients restarted at 6 months after discontinuation , another 10 patients hoped to restart between 9 and 12 months . the prostate volume , ipss , and oabss significantly improved after 6 months of combination therapy . the prostate volume and oabss had deteriorated at the time of restarting dutasteride compared to after 6 months of combination therapy ( fig . , no significant change was observed in qmax or pvr ( data not shown ) . comparison between patients who restarted combination therapy ( n = 12 ) and those who were able to continue monotherapy ( n = 8 ) did not reveal any significant differences in baseline parameters ( table 1 ) other than the intraprostatic architecture . however , for the regrowth rate of the prostate from after 6 months of combination therapy to 6 months after cessation of dutasteride , a significant difference existed between the groups ( 13.5 % vs. 3.0 % , mann - whitney u test , p = 0.017 ) ( fig . although ipss and prostate volume improved in the monotherapy group at 6 months after combination therapy , qmax and oabss did not differ statistically during the study period ( data not shown ) . combination therapy using an alpha blocker and dutasteride will improve luts in bph patients , especially in patients with a large prostate . jeong et al . reported that regrowth of the prostate occurs after discontinuation of 5 - alpha reductase inhibitors and results in worsening of the ipss . they concluded that discontinuation of tamsulosin did not result in worsening of the ipss in bph patients with moderate ipss . also reported in their prospective randomized ( smart - 1 ) study that bph patients with moderate ipss might be able to discontinue alpha blocker use after combination therapy with dutasteride . however , patients with a severe ipss ( 20 ) experienced deterioration of their symptoms . those authors concluded that such patients might benefit from continuous combination therapy . reported the natural history of bph and categorized it into 3 groups according to the internal architecture of the prostate on transrectal ultrasound . they concluded that future prostatic enlargement differed among the architecture types . in group 3 , the same regrowth phenomenon may occur even after shrinkage by dutasteride depending on the intraprostatic architecture . in other words , in some patients , the effect of dutasteride will be maintained even after discontinuation of the medication . our study showed that patients with rapid regrowth after discontinuation tended to hope to restart dutasteride ( fig . however , we have to seek predictive factors for future rapid regrowth to select good candidates for withdrawal treatment at baseline . in this study , thus , being in group 3 was a risk factor for restarting compared with the other groups at baseline ( p = 0.008 , mann - whitney u test ) ( table 1 ) . consideringthat , the intraprostatic architecture may be useful to distinguish patients able to withdraw from dutasteride from others at the start of combination therapy . although previous studies evaluated patients ' symptoms after discontinuation of dutasteride or the alpha - 1 blocker according to the ipss , storage symptoms were not reported in detail . bph patients with oab often suffer from bother and it is hard to treat symptoms like nocturia . evaluation for changes in storage symptoms during discontinuation of combination therapy is essential for maintaining the patient 's quality of life . in our study , worsening of the oabss after discontinuation was seen and eventually led to restarting the 5 - alpha reductase inhibitor . thus , after discontinuation , rapid prostatic regrowth occurred in some patients and storage symptoms worsened , which finally resulted in restarting combination therapy . therefore , rapid regrowth may be a surrogate phenomenon to determine if discontinuation is sustainable . in addition , detailed evaluation of the patient 's intraprostatic architecture at baseline and the deterioration of storage symptoms during follow - up may help clinicians decide if continuation of withdrawal is feasible . on the other hand , therefore , qmax and pvr might not be appropriate surrogate parameters . in this study , patients with group 3 intraprostatic architecture at baseline may experience rapid regrowth , which will result in restarting combination therapy . follow - up of patients treated with the withdrawal strategy should be conducted by using transrectal ultrasound to evaluate prostate regrowth , and a questionnaire should be used to determine storage symptoms . in addition , interpretation of the type of intraprostatic architecture evaluated by transrectal ultrasound may differ by operator , which could lead to bias to some extent . in addition , prostate volume was not strictly defined in the inclusion criteria of the study . although intraprostatic architecture may be a factor for predicting future regrowth after the withdrawal of treatment , the continued monotherapy group had a low proportion of group 3 patients . to verify our conclusions , a study with a large number of patients is essential in the future . intraprostatic architecture may be a predictive factor for rapid regrowth after discontinuation of dutasteride and whether the patient is a good candidate for withdrawal .\noutput:\n" }, { "from": "agent", "value": "purposewe conducted a prospective single - center study to evaluate the possibility of discontinuation of dutasteride after combination therapy with an alpha blocker for benign prostatic hyperplasia ( bph ) . materials and methodswe prospectively treated bph patients with an alpha blocker and dutasteride ( 0.5 mg / d ) . patients who had been treated with alpha blockers against bph for more than 2 months were eligible , and 20 patients were included in the study . after 6 months of combination therapy , dutasteride was discontinued . patients were followed for 12 months after cessation . prostate volume , intraprostatic architecture determined by transrectal ultrasound , peak urinary flow rate , postvoid residual urine volume , and the serum prostate - specific antigen level were evaluated every 6 months , and the international prostate symptom score and overactive bladder symptom score ( oabss ) every 3 months . patients were allowed to restart dutasteride during the follow - up period according to their desire.resultstwelve patients ( 12/20 , 60 % ) restarted the combination therapy from 6 to 12 months into the follow - up period . for patients who restarted dutasteride , the prostate volume and oabss had increased and worsened after discontinuation , respectively . a visible transition zone with a clear border on transrectal ultrasound at baseline and regrowth of the prostate after discontinuation of dutasteride were risk factors for restarting the therapy ( mann - whitney u test : p = 0.008 , p = 0.017 ) . conclusionsprostatic enlargement after discontinuation of dutasteride differs among patients . rapid regrowth of the prostate leads to deterioration of storage symptoms and a tendency to restart dutasteride . baseline intraprostatic architecture may be a predictive factor for whether the patient is a good candidate for discontinuation ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: cervical ossification of the posterior longitudinal ligament ( opll ) may compress the spinal cord and nerve roots , leading to sensory and motor dysfunction . although the majority of patients with the condition are asymptomatic , when opll manifests as cervical myelopathy , non - surgical intervention is often ineffective to arrest the progression of neural deficit . it is well recognized that surgery should be performed before irreversible damage to the nervous system occurs , to avoid further deterioration of spinal cord function . however , the optimal surgical approach remains controversial .1 when planning for surgery , surgeons must take into consideration the region and extent of the opll , as well as the degree of canal stenosis . the surgery should achieve sufficient decompression and prevent further progression of symptoms .2 both anterior and posterior approaches have their advantages as well as disadvantages . the anterior approach can directly relieve compression , but the procedure is more complicated and prone to an increased risk of spinal cord injury . moreover , the anterior decompression and fusion is associated with complications including pseudoarthrosis , implant failure or movement , and symptomatic adjacent segment spondylosis , which have drawn attention in recent years .310 posterior approach can also provide canal decompression , but the degree of decompression is sometimes insufficient since the ventral compression persists . instability following laminectomy has also raised concerns .1114 the present study was designed to compare anterior corpectomy , decompression and fixation and posterior laminectomy , decompression and fixation for treatment of cervical opll involving multiple levels ( three levels or more ) , and to evaluate the factors that influence the outcome of the two approaches . fifty six patients who presented between january 2005 and december 2008 and met the following criteria were recruited : 1 ) underwent anterior or posterior surgery for cervical opll involving three levels or more ; 2 ) with complete medical records and related radiographic data , including preoperative and postoperative x - rays , computed tomography ( ct ) and magnetic resonance imaging ( mri ) ; 3 ) underwent canal decompression , fusion and internal fixation ; 4 ) with 24 months or more of followup . patients with spinal injuries due to trauma were excluded [ table 1 ] . clinical details of two groups anterior approach : the patients were placed in the supine position with the head slightly extended . the cervical spine was exposed through a standard left sided robinson - smith anterior approach . after the ventral annulus fibrosus was removed , a curette and a laminectomy rongeur were used to excise the vertebra . a sharp scalpel was used to cut the opll along the slot under direct vision . the ossified ligament was carefully resected . in case of severe adhesion of the opll to the dura or ossified dura , then , a titanium mesh cage and plate combined with a bone graft was used for the fixation . subsequently , paraspinous muscles were peeled to expose the bilateral laminae of the affected vertebrae . margel 's method was used to place pedicle screws on the levels to be decompressed . the starting point for the pedicle screw was just medial to the hillock of the lateral mass in the coronal plane and midway between the surfaces of the superior and inferior articular process . next , a hand drill was inserted into the starting hole , angling laterally about 20 and parallel to the facet joint in the sagittal plane . this could be judged best by placing a thin , flat instrument into the joint to be fused . drilling proceeded carefully just to , but not through , the second cortex , as bicortical fixation has not been demonstrated to be of biomechanical superior . a depth gauge was then inserted to determine screw length , and then a pedicle screw system was used for fixation . the laminae were resected , and small wedges of bone were placed adjacent to bilateral joints to facilitate fusion . after surgeries , the patients were ordered to wear neck braces for 3 months for protection . x - rays , cts and mri were taken 1 week , 3 months , 6 months , 12 months , and 24 months after surgery , and at the last follow - up . the japanese orthopaedic association ( joa ) scoring system was used to assess the improvement of neurological status after the operation . the improvement rate ( ir ) was calculated as follows : 4 ir = ( postoperative joa score preoperative joa score ) / ( 17 preoperative joa score ) 100 % . surgical outcome was defined as excellent ( ir 75 % ) , good ( 75 % ir 50 % ) , fair ( 50 % ir 25 % ) , or poor ( ir 25 % ) . statistical analyses were performed using spss statistical software ( version 13.0 , spss , chicago , il , usa ) . paired t - test and group t - test were used for comparison of quantitative data . fifty six patients who presented between january 2005 and december 2008 and met the following criteria were recruited : 1 ) underwent anterior or posterior surgery for cervical opll involving three levels or more ; 2 ) with complete medical records and related radiographic data , including preoperative and postoperative x - rays , computed tomography ( ct ) and magnetic resonance imaging ( mri ) ; 3 ) underwent canal decompression , fusion and internal fixation ; 4 ) with 24 months or more of followup . patients with spinal injuries due to trauma were excluded [ table 1 ] . anterior approach : the patients were placed in the supine position with the head slightly extended . the cervical spine was exposed through a standard left sided robinson - smith anterior approach . after the ventral annulus fibrosus was removed , a curette and a laminectomy rongeur were used to excise the vertebra . a sharp scalpel was used to cut the opll along the slot under direct vision . the ossified ligament was carefully resected . in case of severe adhesion of the opll to the dura or ossified dura , then , a titanium mesh cage and plate combined with a bone graft was used for the fixation . subsequently , paraspinous muscles were peeled to expose the bilateral laminae of the affected vertebrae . margel 's method was used to place pedicle screws on the levels to be decompressed . the starting point for the pedicle screwwas just medial to the hillock of the lateral mass in the coronal plane and midway between the surfaces of the superior and inferior articular process . next , a hand drill was inserted into the starting hole , angling laterally about 20 and parallel to the facet joint in the sagittal plane . this could be judged best by placing a thin , flat instrument into the joint to be fused . drilling proceeded carefully just to , but not through , the second cortex , as bicortical fixation has not been demonstrated to be of biomechanical superior . a depth gauge was then inserted to determine screw length , and then a pedicle screw system was used for fixation . the laminae were resected , and small wedges of bone were placed adjacent to bilateral joints to facilitate fusion . after surgeries , the patients were ordered to wear neck braces for 3 months for protection . x - rays , cts and mri were taken 1 week , 3 months , 6 months , 12 months , and 24 months after surgery , and at the last follow - up . the japanese orthopaedic association ( joa ) scoring system was used to assess the improvement of neurological status after the operation . the improvement rate ( ir ) was calculated as follows : 4 ir = ( postoperative joa score preoperative joa score ) / ( 17 preoperative joa score ) 100 % . surgical outcome was defined as excellent ( ir 75 % ) , good ( 75 % ir 50 % ) , fair ( 50 % ir 25 % ) , or poor ( ir 25 % ) . statistical analyses were performed using spss statistical software ( version 13.0 , spss , chicago , il , usa ) . paired t - test and group t - test were used for comparison of quantitative data . of the 56 patients included in our study , 26 were treated with anterior approach and the rest 30 treated with posterior approach . there were no significant differences in the baseline characteristics of the two groups , including the preoperative canal occupancy rate , canal sagittal diameter , cervical curvature , type of opll , the mean preoperative cervical range of motion ( rom ) in the sagittal plane and the joa score [ table 1 ] . the duration of surgery for the anterior and posterior approaches were 16145 min ( range 120210 min ) and 12534 min ( range 100180 min ) , respectively . the blood loss in anterior and posterior approaches was 763122 ml ( range 4001700 ml ) and 51694 ml ( range 4001200 ml ) , respectively . the posterior approach required significantly lesser time and resulted in significantly lesser blood loss than the anterior approach . the number of vertebrae removed was 1.92 ( range 13 vertebrae ) on average and the mean of fusion extent was 3.92 ( range 35 ) vertebrae in the anterior approach group . in the posterior approach group , the number of vertebrae lamina removed was 3.67 ( range 35 vertebrae lamina ) on average and the mean of fusion extent was 4.27 ( range 36 ) vertebrae . all cases were followed up for 2 years or more . for the anterior and posterior approaches , the patients were followed up for 36.36.4 months ( range 2457 months ) and 37.66.7 months ( range 2469 months ) , respectively . at the last follow - up , the mean rom in the sagittal plane of the anterior approach group decreased from preoperative 67.63.4 to postoperative 45.72.6 . in the posterior group , the preoperative value of 64.53.3 dropped to 41.73.0 . the mean preoperative rom and the rom at the last follow - up were not significantly different between the two groups . the mean postoperative joa score of the anterior approach group increased to 14.21.6 points from the preoperative 9.31.2 points , with a mean improvement rate of 58.6 % 10.4 % and 65 % of the patients had excellent or good outcomes . in the posterior approach group , the meanpostoperative joa score improved from 9.11.1 to 13.71.5 points postoperatively ; the average improvement rate was 54.8 % 9.7 % and 60 % of patients had excellent or good outcomes . the preoperative and the last follow - up joa scores were not significantly different between the two groups . there were significant differences in the joa score at the last follow - up between the two groups with canal occupancy ratios 50 % , and the anterior approach group had better outcomes . however , no noticeable association was found between cervical curvature or type of opll and outcome in the two groups [ tables 14 and figure 1 ] . surgical outcomes in the anterior or posterior groups with different canal occupancy ratio surgical outcomes in the anterior or posterior groups with different cervical curvature surgical outcomes in the anterior or posterior groups with different types of opll a 66 - year - old man , with a continuous cervical opll involving multiple levels . ( a c ) preoperative lateral x - ray , cervical plain ct and mri demonstrated significant compression of the spinal cord . ( d ) postoperative lateral x - ray showing satisfactory fixation with a pedicle screw system . ( e , f ) plain mri on the day after surgery and 24 months postoperative demonstrated good morphology of the spinal cord followup of same patient . his preoperative joa score was 8 , the postoperative joa score was 15 , and his ir was 78 % . ( a - d ) his cervical rom in the sagittal plane decreased from 50 preoperative to 40 postoperative . at the last follow - up , no progression of the opll or related complications was observed . the outcome was satisfactory the cerebrospinal fluid leaks were seen in two cases in the present study in anterior approach surgeries . both of them were managed successfully by keeping the patients in supine positions for 5 and 7 days . one patient had quadriplegia after surgery and was presumably due to a gradually resected bony structure causing a slow decompression that led to repeated bulging of the spinal cord , eventually severing the spinal cord [ figure 2 ] . twelve months postoperatively , a patient demonstrated asymptomatic implant subsidence , and no specific measure was taken . these two patients were considered as having poor outcome . a 45 - year - old man , who also suffered from continuous cervical opll of multiple levels . ( a c ) preoperative lateral x - ray , cervical plain ct and mri demonstrated significant compression of the spinal cord . the patient underwent subtotal c4c6 corpectomy and decompression , and a titanium mesh cage and plate combined with bone graft was used for the fixation . ( d ) postoperative lateral x - ray showing satisfactory reduction with a titanium mesh cage and plate , ( e , f ) but the degeneration of the spinal cord can be observed at the day after surgery and 24 months postoperative , respectively followup of same patient . he was paralyzed postoperatively , presumably because the gradually resected bony structure caused a gradual decompression which led to repeated bulging of the spinal cord and induced a partial severing of the spinal cord . the preoperative joa score was 9 and the joa score 24 months postoperative was 9 , with no improvement . ( a - d ) the rom in the sagittal plane decreased from 60 preoperative to 50 postoperative . the outcome was poor one case of cerebrospinal fluid leakage in posterior approach was treated by local pressure and by confining the patient in the supine position for 5 days . two cases suffered from c5 nerve root injury ( one was bilateral and the other was unilateral ) . they had hypoesthesia and pain of the lateral arm and weakness of the biceps and deltoid muscles . the time of initial onset of c5 palsy symptoms were all within 8 hours postoperative . the patients were treated conservatively by oral neurotrophic drugs , hyperbaric oxygen therapy and exercise . symptoms of the other patient were relieved , and the patient was considered as having poor outcome . one patient experienced progression of the opll and had deterioration of nervous function after 45 months , which was successfully managed by anterior decompression and fixation , and was also considered as having poor outcome . the cerebrospinal fluid leaks were seen in two cases in the present study in anterior approach surgeries . both of them were managed successfully by keeping the patients in supine positions for 5 and 7 days . one patient had quadriplegia after surgery and was presumably due to a gradually resected bony structure causing a slow decompression that led to repeated bulging of the spinal cord , eventually severing the spinal cord [ figure 2 ] . twelve months postoperatively , a patient demonstrated asymptomatic implant subsidence , and no specific measure was taken . these two patients were considered as having poor outcome . a 45 - year - old man , who also suffered from continuous cervical opll of multiple levels . ( a c ) preoperative lateral x - ray , cervical plain ct and mri demonstrated significant compression of the spinal cord . the patient underwent subtotal c4c6 corpectomy and decompression , and a titanium mesh cage and plate combined with bone graft was used for the fixation . ( d ) postoperative lateral x - ray showing satisfactory reduction with a titanium mesh cage and plate , ( e , f ) but the degeneration of the spinal cord can be observed at the day after surgery and 24 months postoperative , respectively followup of same patient . he was paralyzed postoperatively , presumably because the gradually resected bony structure caused a gradual decompression which led to repeated bulging of the spinal cord and induced a partial severing of the spinal cord . the preoperative joa score was 9 and the joa score 24 months postoperative was 9 , with no improvement . ( a - d ) the rom in the sagittal plane decreased from 60 preoperative to 50 postoperative . the outcome was poor one case of cerebrospinal fluid leakage in posterior approach was treated by local pressure and by confining the patient in the supine position for 5 days . two cases suffered from c5 nerve root injury ( one was bilateral and the other was unilateral ) . they had hypoesthesia and pain of the lateral arm and weakness of the biceps and deltoid muscles . the time of initial onset of c5 palsy symptoms were all within 8 hours postoperative . the patients were treated conservatively by oral neurotrophic drugs , hyperbaric oxygen therapy and exercise . symptoms of the other patient were relieved , and the patient was considered as having poor outcome . one patient experienced progression of the opll and had deterioration of nervous function after 45 months , which was successfully managed by anterior decompression and fixation , and was also considered as having poor outcome . opll begins with a pathological extracellular hyperplasia and hypertrophy of the posterior longitudinal ligament , leading to ectopic ossification at the spine . cervical opll causes canal stenosis and compression of the spinal cord and nerve roots , and subsequently clinical symptoms and signs of myelopathy .15 factors that influence the onset and progression of cervical opll include the compression of the ossified ligament , a congenitally narrow spinal canal , segmental instability and trauma . most surgeons believe that surgical intervention should be applied before irreversible myelopathy occurs , so that the progression can be arrested and deterioration of spinal function is prevented . however , the choice of anterior versus posterior approach as surgical strategy remains controversial .1 direct removal of the opll by anterior surgery offers better decompression , and hence is theoretically the optimal option . nevertheless , reviewing literature shows that anterior corpectomy and fusion is better suited for opll involving one or two levels .41618 for opll of three levels or more , can a similar effect be obtained by anterior surgery ? we conclude from our study that the anterior approach for multiple levels can achieve satisfactory outcomes , and the patients with an canal occupancy ratio of opll 50 % managed by anterior surgery had better outcomes . however , for those with more severe stenosis , anterior approaches are more difficult and associated with higher risks and complications ; also , it is a technically demanding procedure and should be performed by an experienced surgical team . opll of multiple levels leading to severe canal stenosis , the available space required for removal of the ossified ligaments is limited . this leads to repeated trauma to the spinal cord , which might cause spinal damage or even paraplegia . moreover , internal fixation of multiple levels is susceptible to loosening and the mobility of the cervical spine may be impaired .34 even combined with anterior placement of titanium plates , the nonunion rate was reported to be as high as 618 % .56 among the anterior approach group , one case had an implant subsidence , and although the case was asymptomatic , a close follow - up was warranted . therefore , we suggest that the patients should be ordered to wear neck braces for protection until the x - ray shows incorporation of the intervertebral bone graft . posterior laminectomy , decompression and fixation is a well - established technique and is relatively simple and safe . we found that for opll of three levels or more , it is an effective strategy . in most of the cases , it can also improve the cervical curvature through pedicle screw system and provide immediate and long - term stability of the cervical spine , and avoid development of kyphosis . theoretically , it can reduce the progression of cervical opll .1920 lack of immediate stability after laminoplasty or laminectomy without fixation might lead to development of postoperative kyphosis and progression of opll , eventually causing the relapse of myelopathy .12 in our study , at the last follow - up , no kyphosis was observed . nevertheless , even when opll progresses after posterior cervical decompression , because of the available space from resected lamina , a secondary anterior decompression can excise intervertebral discs or floated opll and a simultaneous bone graft combined with fusion and fixation can be done . this can effectively solve the progression of opll and minimize complications due to posterior decompression surgery . compared with the anterior approach , posterior surgery is safer , less technically demanding , and is associated with less blood loss and better long - term outcomes .21 posterior surgery also has its disadvantages . first , since the compression is located anteriorly , decompression in posterior surgery is indirect , without removal of the opll . our study showed that when the canal occupancy ratio of opll was more than 50 % , the outcomes were less favourable . moreover , cervical opll is often accompanied by various levels of cervical degeneration , spinal disc herniation and nerve root compression , and posterior surgery is ineffective for decompression of nerve roots , causing postoperative symptoms . furthermore , it has been reported that segmental root palsy occurred in 3.228.6 % of patients .11 the mechanisms have not been elucidated so far , although most surgeons believe that the main reason might be that a floated spinal cord after posterior decompression causes traction on the nerve roots , leading to nerve root edema . we believe that sustaining a physiological cervical curvature during surgery and reliable internal fixation and fusion could reduce prominently the incidence of this complication . the critical step of treatment for cervical opll involving multiple levels , is effective decompression and immediate cervical spine stability . both anterior and posterior decompression and fixation can achieve this therapeutic aim . in patients with the canal occupancy ratio of opll 50 % , treatment by the anterior approach can have better outcomes , though it is more difficult and associated with higher risks and complications . despite its limitations in patients with high occupancy ratio oplls , through the multiple - level laminectomy , posterior fixation can achieve effective decompression , maintaining or restoring stability of the cervical spine , and thereby improving neural outcome and preventing the progression of opll . we believe that the posterior indirect decompression and fixation may be adopted as the primary treatment for cervical opll involving multiple levels with the canal occupancy ratios of opll 50 % .\noutput:\n" }, { "from": "agent", "value": "background : the optimal approach to provide satisfactory decompression and minimize complications for ossification of the posterior longitudinal ligament ( opll ) involving multiple levels ( 3 levels or more ) remains controversial . the purpose of this study was to compare the results of two surgical approaches for cervical opll involving multiple levels ; anterior direct decompression and fixation , and posterior indirect decompression and fixation . we present a retrospective review of 56 cases followed at a single institution.materials and methods : we compared patients of multiple levels cervical opll that were treated at a single institution either with anterior direct decompression and fixation or with posterior indirect decompression and fixation . the clinical records of the patients with a minimum duration of follow - up of 2 years were reviewed . the associated complications were recorded.results : fifty - six patients constitute the clinical material . 26 cases were treated by anterior corpectomy and fixation and 30 cases received posterior laminectomy and fixation . the two populations were similar . it was found that both anterior and posterior decompression and fixation can achieve satisfactory outcomes , and posterior surgery was accomplished in a shorter period of time with lesser blood loss . although patients had comparable preoperative japanese orthopaedics association ( joa ) scores , those with a canal occupancy by opll more than 50 % and managed anteriorly had better outcomes . however , for those with more severe stenosis , anterior approach was more difficult and associated with higher risks and complications . despite its limitations in patients with high occupancy oplls , through the multiple level laminectomy , posterior fixation can achieve effective decompression , maintaining or restoring stability of the cervical spine , and thereby improving neural outcome and preventing the progression of opll.conclusions : the posterior indirect decompression and fixation has now been adopted as the primary treatment for cervical opll involving multiple levels with the canal occupancy by opll < 50 % at our institution because this approach leads to significantly less implant failures . those patients with the occupancy 50 % managed with anterior approach surgeries had better outcomes , but approach was more difficult and associated with higher risk and complications ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: it was reported that a percentage of 1 % and 12.7 % of cases in which patients present both a solid neoplasm and aaa . the increasing incidence of this two synchronous diseases is probably due to better life expectancy of population , diffusion of cancer staging which allows diagnosis of asymptomatic aaa and development of imaging techniques that often permits diagnosis of silent cancer in patients with aaa . there have been reported the excellent results in patients who have undergone open aaa repair combined resection of renal tumor with one - staged procedure , however there is no consensus on the best therapeutic approach for patients with simultaneous aaa and renal tumor . there is still a concern that treating both pathologies during the same procedure is the risk of aortic graft infection and rupture . although the long - term effectiveness is still controversial , endovascular aneurysm repair has recently been proposed as a treatment option for patients with aaa . herein , we report our experience of a successful combination of minimally invasive treatments of endovascular aneurysm repair ( evar ) and retroperitoneal laparoscopic surgery in a staged management of elderly and high - risk patient with renal tumors and aaa . an 82 - year - old male patient with hypertension ( ht ) and hyperlipidemia ( hl ) was referred to the department of vascular surgery in our hospital because of an incidental finding of left renal tumors and aaa , following an ultrasonography for medical work up by his physician . computed tomography angiography of the abdomen / pelvis revealed an aaa and enhancing 5.1 cm and 4.6 cm left renal masses ( figure 1 ) . left renal cell carcinoma was suspected and the patient was referred to our department . from these findings , he was clinically diagnosed left renal cell carcinoma stage ( t1bn0 m0 ) . his significant past medical history included ht , hl , and chronic renal insufficiency ( s - cre ; 1.2 mg / dl ) . considering his comorbidities and high age , a staged approach that consisted of evar followed by retroperitoneal laparoscopic radical nephrectomy was planned . the patient underwent successful placement of an aortic endograft through bilateral femoral artery exposure under general anesthesia ( figure 2 ) . three months later the patient underwent a left retroperitoneal laparoscopic radical nephrectomy . utilizing 4 port technique , the procedure was uncomplicated and performed with no trouble associating with the repaired aaa ( figure 3 ) . estimated blood loss was only 94 ml . post nephrectomy , retroperitoneal abscess was occurred , but it was cured by percutaneous drainage . pathology revealed clear cell carcinoma in solid masses of 4 cm and 5 cm , which were presumed to be t1bn0m0 renal cell carcinoma . s - creatinine ( mg / dl ) was elevated from baseline of 1.11.5 to 1.7 in 6 months as expected . figure 1abdominal computed tomography ( ct ) scan performed for the evaluation of renal tumors . ( a ) upper tumor ; ( b ) lower tumor ; ( c ) abdominal aortic aneurysm ( 3d ct ) . ( a ) upper tumor ; ( b ) lower tumor ; ( c ) abdominal aortic aneurysm ( 3d ct ) . figure 2computed tomography ( ct ) scan performed for the evaluation of abdominal aortic aneurysm after endovascular aneurysm repair . ( a ) plain ct ; ( b ) enhanced ct . computed tomography ( ct ) scan performed for the evaluation of abdominal aortic aneurysm after endovascular aneurysm repair . ( a ) plain ct ; ( b ) enhanced ct . figure 3intraoperative photograph of laparoscopic nephrectomy after endovascular aneurysm repair . ( a ) before nephrectomy ; ( b ) after nephrectomy . laparoscopic radical nephrectomy has become an international standard of care for medium to large renal tumors in academic and urban centers . until now , many renal laparoscopic procedures were carried out via two approaches , transperitoneal and retorperitoeal . there have been no controlled randomized studies that have compared the two approaches . in this case , considering the large aaa , retroperitoneal approach was easier and safer than transperitoneal with respect to the approach to renal artery . partial nephrectomy is currently considered the standard for most t1a ( 4 cm ) renal tumors and acceptable alternative to radical nephrectomy for select t1b ( 4 cm ) renal tumors . as the result of considering with double tumors and each tumor size 4 cm , we concluded partial nephrectomy was very risky and hard . finally , we concluded that retroperitoneal laparoscopic radical nephrectomy was the optimal procedure for him . recently , evar to exclude aaa was introduced for patients of poor health status considered unfit for major surgery , and the qualified patient has also quickly replaced open aneurysm surgery for the management of aaa . one - staged open procedure in the patients with aaa and renal tumors may be associated with an increased risk of infection of the vascular prosthesis . infection of vascular prosthesis is potentially life threatening and dangerous for elderly and high - risk patients . this disadvantage is not less relevant in patients , which can be treated laparoscopic surgery or evar than open surgery . in our case , considering high age and the comorbidities , evar has been shown to be associated with a lower procedural mortality and morbidity in the short term , addition to shorter admission times and quicker recovery and offers the possibility of excluding the aaa rapture before treating the nephrectomy . furthermore , left radical nephrectomy through retroperitoneal approach was very useful and safe with a good orientation of aaa in which endograft was inserted . thus , the risk of direct graft contamination and rupture appears to be more markedly reduced . therefore we recommend a combination of minimally invasive treatments of evar and laparoscopic surgery in a staged approach , which allowed a prompt selective patient recovery .\noutput:\n" }, { "from": "agent", "value": "the association between abdominal aortic aneurysm ( aaa ) and renal tumor is becoming more frequent , and the increasing incidence of this synchronous diseases raised questions about the procedures of treatment . in most of the previous cases , open nephrectomy and aaa surgery have been reported , however in high risk and elderly patients , the procedure is life threatening . we present a successful staged treatment of aaa and renal tumor using novel minimally invasive treatment with endovascular aneurysm repair and retroperitoneal laparoscopic radical nephrectomy in an elderly and high - risk case ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: although reports on the frequency of the disease differ , it occurs in fewer than 1 % of patients with mild to moderate hypertension and in 30 % of those with acute , severe , or refractory hypertension . the causes of renal artery stenosis include fibromuscular dysplasia , takayasu arteritis , and arteriosclerosis . in particular , atherosclerotic renal artery stenosis is the most common cause and is increasing in frequency because of lifestyle diseases , such as hypertension , diabetes mellitus , and dyslipidemia . in addition , it leads to ischemic atherosclerotic nephropathy , which accounts for 1114 % of cases of end - stage renal disease . atherosclerotic renal artery stenosis is important not only for rvh but also as one of the manifestations of generalized atherosclerotic disease . furthermore , it is reported that the risk of cardiovascular death is increased in patients with atherosclerotic renal artery sclerosis . herewe present the case of a 61 - year - old man with rvh caused by chronic total occlusion of left renal artery resulting in an atrophic kidney . although the left kidney was atrophic and seemed to be almost nonfunctional on renography , renal vein sampling showed that the endocrine function of the left kidney was preserved . along with the findings of multidetector - row computed tomography ( mdct ) , we elected to perform percutaneous transluminal renal angioplasty ( ptra ) with stent placement . the blood pressure decreased gradually to within the normal range after ptra , and the laboratory data on endocrine function and the renography findings drastically improved . we present the patient s clinical course and the effectiveness of ptra for atrophic kidney . the patient was a 61 - year - old man with no medical history . in october 2012 , a local doctor first identified hypertension in this patient . in addition , his laboratory data showed hypokalemia , and both the plasma renin activity ( pra ) and plasma aldosterone concentration ( pac ) were elevated . there was a strong suspicion of secondary hypertension , and he was therefore referred to our hospital . he visited our hospital and was admitted as a hypertensive emergency . on admission , he had a blood pressure of 200/102 mmhg and a pulse of 78 beats / min . physical examination revealed a systolic murmur , grade ii / vi , in the left parasternal area with accentuation of the aortic second heart sound and a typical bruit in the umbilical region . the lungs were clear on auscultation , and no edema of the lower limbs was present . on ophthalmologic examination , keith wagener baker classification grade iv hypertensive retinopathy was noted . the laboratory data showed a blood urea nitrogen ( bun ) level of 16 mg / dl , serum creatinine level of 1.04 mg / dl , and serum potassium level of 3.2 meq / l . pra was 20 ng / ml / h and pac was 515 pg / ml . arterial blood gas analysis on room air showed a ph of 7.42 , paco2 of 43 torr , pao2 of 80 torr , and a bicarbonate level of 28.1 mmol / l . chest x - ray demonstrated clear lung fields , and an electrocardiogram showed strain t waves on ii , iii , avf , v5 , and v6 , as well as a high voltage ( sv1 + rv5 = 50 mm ) . renal ultrasonography showed that the right kidney was 12.05.75.7 cm in size and the left was 8.84.74.3 cm . after admission , we stabilized the blood pressure with continuous infusion of nicardipine . on the third day , the intravenous infusion of nicardipine was changed to take controlled - release nifedipine by mouth . a dose of controlled - release nifedipine , 60 mg / day , was not successful in lowering the blood pressure , so methyldopa , 750 mg / day , was added . mdct showed occlusion of the left renal artery , atrophy of the left kidney , and mild stenosis of the right renal artery ( fig . collateral vessels to the left renal artery around the left kidney were identified , and the left renal artery was determined to have chronic total occlusion . tc - mercaptoacetyltriglycine ( tc - mag3 ) renography revealed a marked decrease in the effective renal plasma flow of the left kidney ( left side , 22.7 ml / min ; right side , 247.2 ml / min ) , and no peak curve of the left kidney on renogram ( fig .2 ) , suggesting that the left kidney might have no residual renal function . to determine the pathophysiology , angiography and renal vein sampling were performed . aortic angiography showed mild stenosis of the right kidney artery and total occlusion of the left kidney artery ( fig . renal vein sampling indicated that the pra of the left vein was 3.2 times higher than that of the right vein ( left , 48 ng / ml / h ; right , 15 ng / ml / h ) . based on these findings , we concluded that the left kidney was atrophic and had almost no residual renal function because of chronic total occlusion , but the endocrine function remained . mdct showed that the total occlusion lesion of the left renal artery was short ( length , 1.5 cm ) with no calcification . therefore , we decided to perform ptra after informed consent to treatment and complications . a 6.5 - f sheathless guiding catheter ( parent plus ptra ; medikit , tokyo , japan ) was positioned at the ostial part of the left renal artery . a 0.014 - inch guide wire ( shevalier ; cordis , east bridgewater , nj , usa ) was able to cross into the distal true channel ( fig . predilatation was performed with a 1.5 - mm balloon ( make way plus ; kawasumi , tokyo , japan ) at 12 atm . further dilatation was performed with a 4 - mm balloon ( aviator plus ; cordis ) at 12 atm . after predilatation , a 5.018 - mm stent ( palmaz gensis ; cordis ) was deployed across the lesion at 14 atm with a good final result , and the blood flow of the left renal artery was completely recovered ( fig .4 b ) . there were no complications such as dissection , perforation , or embolization . the next day , blood pressure decreased gradually to 100120 / 6080 mmhg after ptra , and methyldopa was discontinued ( fig .5 a ) . before discharge , both the pra and pac were much lower than on admission , 0.2 ng / ml / h and 96.5 pg / ml , respectively . tc - mag3 renography revealed a moderate decrease in the effective renal plasma flow of the right kidney and a mild increase in that of the left kidney ( left side , 53.0 ml / min ; right side , 199.7 ml / min ) ( fig . 5b ) . fig .1 multidetector - row computed tomography images of the kidneys and vessels demonstrating occlusion of left renal artery , atrophy of left kidney , and mild stenosis of right renal artery . b three - dimensional view . note that vessels collateral to the left renal artery around the left kidney were richfigthe effective renal plasma flow of the left kidney markedly decreased and showed no peak curvefig .5 a clinical course . cr controlled release , pra plasma renin activity , pac plasma aldosterone concentration , nic nicardipine , ptra percutaneous transluminal renal angioplasty . c tc - mag3 renogram 1 year after ptra multidetector - row computed tomography images of the kidneys and vessels demonstrating occlusion of left renal artery , atrophy of left kidney , and mild stenosis of right renal artery . a coronal plane view . b three - dimensional view . note that vessels collateral to the left renal artery around the left kidney were rich tc - mercaptoacetyltriglycine ( tc - mag3 ) renogram . the effective renal plasma flow of the left kidney markedly decreased and showed no peak curve digital subtraction abdominal and renal angiography . a aortic angiography . rt right , lt left , sma superior mesenteric artery a percutaneous renal angioplasty ( ptra ) . b renal angiography after ptra a clinical course . cr controlled release , pra plasma renin activity , pac plasma aldosterone concentration , nic nicardipine , ptra percutaneous transluminal renal angioplasty . b tc - mag3 renogram after ptra . c tc - mag3 renogram 1 year after ptra one year after the procedure , we re - evaluated tc - mag3 renography and computed tomography . compared with previous findings , the renogram revealed a peak curve of the left kidney ( fig .5 c ) , and further increase in the effective renal plasma flow of the left kidney ( 77.1 ml / min ) and a decrease in that of the right kidney ( 179.7 ml / min ) ( fig . 6 ) . furthermore , the computed tomogram demonstrated an improvement in the atrophy of the left kidney ( fig .7 a , b ) , and the kidney function also improved to a serum creatinine level of 0.74 mg / dl.fig . erpf effective renal plasma flow computed tomography images of the kidneys demonstrating improvement in atrophy of the left kidney . we report here the successful treatment of rvh caused by chronic total occlusion with an atrophic kidney , using ptra and adjunct stent placement . the 2006 american college of cardiology / american heart association guidelines state the recommendations for ptra in patients with failure of optimal medical therapy to control blood pressure . although there was the possibility that our patient s blood pressure could be controlled only by medication , the ptra improved not only the blood pressure , but also both pra and pac . therefore this treatment may reduce the future requirement of medications in this patient . in patients with rvh , first , we excluded takayasu arteritis because there was no sign of fever and a c - reactive protein level within normal limits . next , we considered that the possibility of fibromuscular dysplasia was low because the lesion was in the proximal portion of the renal artery , which is not common in patients with fibromuscular dysplasia . third , we considered the possibility of an acute kidney infarction , but mdct findings did not suggest a partial perfusion defect and there was no arrhythmia such as atrial fibrillation on ambulatory electrocardiogram . moreover , there was no flank or abdominal pain , or other symptoms including nausea and vomiting . therefore , based on the mdct findings that the collateral vessels were rich , we reached the diagnosis of rvh caused by arteriosclerosis . although the therapeutic approach in rvh remains controversial , there are three therapeutic options available : medical therapy , percutaneous angioplasty with or without stent placement , and surgical revascularization or , in some cases , resection of athe effectiveness of angiotensin - converting enzyme and angiotensin ii receptor blockers has made it easy to control blood pressure in patients with rvh . on the other hand , several studies showed the effectiveness of ptra with or without stent placement . a prospective study investigating the efficacy of stent revascularization for the prevention of cardiovascular and renal events among patients with renal artery stenosis is ongoing . . demonstrated the beneficial effect on blood pressure of nephrectomy of the atrophic kidney . nagata et al . first reported successful ptra with stent placement in a patient with a chronic total occluded renal artery in an atrophied kidney . in this case , renal vein sampling was carried out and showed bilateral difference ; this was similarly observed in our case . alchi et al . also evaluated the bilateral difference in a case of chronic renal artery occlusion . therefore , ptra with stent placement might be useful in a case with residual endocrine function that is maintained by collateral blood flow in an atrophic kidney with chronic renal artery occlusion . in the present case , the effective renal plasma flow increased in the left kidney with chronic total occlusion and decreased in the right kidney with mild stenosis , as determined by tc - mag3 renography after ptra . . reported similar outcomes after ptra in 32 patients with unilateral renal artery stenosis . it is unclear whether the treatment is associated with long - term renal benefits ; however , the decrease in effective renal flow in the intact kidney leads to a reduction of the intraglomerular pressure , which surely results in protection of the kidney . in fact , the kidney function in this patient improved to within the normal range . whereas the atrophy in itself is considered to be irreversible in general , it was reversible in the present case . have also reported that there was a significant increase in medullary length in the poststenotic / revascularized kidneys at 6 months after ptra in renovascular hypertensive patients , suggesting that the increase in the effective renal plasma flow may be related to the improvement in the size of atrophic kidney . these findings could provide useful knowledge in considering the indications for ptra . in conclusion , we presented a case of chronic total occlusion in an atrophic kidney treated with ptra . further studies are required to confirm the efficacy of ptra for rvh with an atrophic kidney .\noutput:\n" }, { "from": "agent", "value": "renovascular hypertension is an important cause of secondary hypertension . we present the case of a 61 - year - old man with renovascular hypertension caused by chronic total occlusion of the left renal artery resulting in an atrophic kidney . although renography indicated almost no residual function of the left kidney , renal vein sampling showed a significant increase of renin secretion in the left kidney . the endocrine function of the left kidney was believed to be preserved ; thus , we performed percutaneous transluminal renal angioplasty with stent placement . after the procedure , the patient s blood pressure decreased gradually to within the normal range without adverse events . the laboratory data on endocrine function and the renography findings drastically improved . percutaneous transluminal renal angioplasty is a promising therapeutic procedure for renovascular hypertension with an atrophic kidney ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: congenital anomalies of the urogenital tract are the most common anomalies found in the foetus , neonates and infants , but anterior urethral valves and diverticula are rare . here , we present a case with congenital anterior urethral diverticulum . what is peculiar with this case is that the same patient had two more congenital anomalies ( patent ductus arteriosus and polydactyly ) . a 9 - year - old male child presented with dribbling after micturition and swelling at the distal shaft of the penis since birth [ figure 1 ] . he also had a history of patent ductus arteriosus , which was discovered in his early childhood , for which percutaneous closure was done about a year ago . the patient also had bilateral polydactyly feet ( six toes in each foot ) [ figure 2 ] . pre - operative view of anterior urethral diverticulum polydactyly of both feet on clinical and ultrasonographic examination , we found that the patient had congenital anterior urethral diverticulum [ figure 3 ] . ultrasonography image of anterior urethral diverticulum the diverticulum was excised through a degloving skin incision [ figure 4 ] . postoperatively , the child had normal stream and no follow - up dribbling [ figure 5 ] . intra - operative view showing the opened diverticulum with catheter in situ post - operative view showing a good urinary stream with no fistulasome authors consider anterior urethral valves and diverticula as the same entity , and some consider them to be two distinct entities . it has been suggested that valves cause proximal urethral dilatation with the formation of a sac - like diverticulum . on the other hand , some believe that the distal lip of a diverticulum rises and acts like a valve when the diverticulum is distended with urine . an important differentiating point may be that while congenital anterior urethral valve is covered by corpus spongiosum , congenital anterior urethral diverticulum protrudes through it , and hence , it is covered only by skin . we believe that this distinction is only theoretical , and practically , both are the same because congenital anterior urethral valve , at the time of presentation , is indistinguishable from congenital anterior urethral diverticulum , and the symptoms and management are the same . those arising from the ventral surface of bulbar urethra are most common and present with obstructive symptoms ; while the others , arising from the ventral surface of the urethra near the penile tip are rare , and are more prone to calculus formation . there are various embryologic theories of anterior urethral diverticulum formation such as : ( a ) developmental defect resulting in the weakness of corpus spongiosum ; ( b ) an incomplete hypospadias ; ( c ) cystic dilatation of urethral glands ; ( d ) sequestration of an epithelial rest and ( e ) congenital anterior urethral valve and congenital anterior urethral diverticulum arising from the anterior lip of ruptured syringocele of cowper 's duct . patients usually present complaining of poor urinary flow , post - micturition dribbling , penile ballooning and / or urinary tract infection . the diagnosis of congenital anterior urethral diverticulum / valve can easily be done by a clinical examination , ultrasonography , retrograde urethrography , voiding cystourethrography and / or urethroscopy . in endoscopic surgery , the pouch still persists , hence it can develop a flap again , and re - operation may be required . in these cases , open approach , on the other hand , obviates this , but fistula formation is a potential complication , and in some cases , temporary urinary diversion may be required . congenital anomalies of the urogenital tract are the most common anomalies found in the foetus , neonates and infants , but anterior urethral valves and diverticula are rare\noutput:\n" }, { "from": "agent", "value": "congenital anomalies of the urogenital tract are the most common anomalies found in the foetus , neonates and infants , but anterior urethral valves and diverticula are rare . here , we present a case with congenital anterior urethral diverticulum associated with patent ductus arteriosus and polydactyly ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: in recent years , plant derived polymers have evoked tremendous interest due to their diverse pharmaceutical applications such as diluents , binders , disintegrants in tablets , thickeners in oral liquids , protective colloids in suspensions , gelling agents in gels , and bases in suppository ; they are also used in cosmetics , textiles , paints , and paper - making . the plant based polymers have been studied for their application in different pharmaceutical dosage forms like matrix controlled system , film coating agents , buccal films , microspheres , nanoparticles , and viscous liquid formulations like ophthalmic solutions , suspensions , and implants and their applicability and efficacy has been proven . these have also been utilized as viscosity enhancers , stabilizers , disintegrants , solubilizers , emulsifiers , suspending agents , gelling agents and bioadhesives , and binders in the above mentioned dosage forms . the term mucilage in plants means those substances which are soluble or at least swell very perceptibly in water and which , upon the addition of alcohol , are precipitated in a more or less amorphous or granular mass . mucilage originates in the plant either as a part of the contents of the cell or as a part of the wall thereof . these materials include guar gum , ispaghula husk , galactomannan from mimosa scabrella , gleditsia triacanthos linn ( honey locust gum ) , sesbania gum , mucilage from the pods of hibiscus esculenta , tamarind seed gum , gum copal and gum dammar , agar , konjac , and chitosan . industrial gums and mucilage , which , for the most part , are water - soluble polysaccharides , have enormously large and broad applications in both food and non - food industries . their use depends on the unique physicochemical properties that they provide , often at costs below those of synthetic polymers . manilkara zapota ( linn . ) p. royen syn . is a large , evergreen , forest tree more than 30 m in height a tree belonging to the family sapotaceae . p. royen syn was carried out so as to enable its use as a food additive . an understanding of the physicochemical properties and structural characterization of mucilage is essential in exploiting its potential as a food additive and for other industrial applications . in the present paper , we report morphological , physicochemical and structural aspects of mucilage from seeds of manilkara zapota ( linn . ) the methods employed for the analysis include ( i ) particle size analysis by microtrac , ( ii ) scanning electron microscopy ( sem ) , ( iii ) gel permeation chromatography ( gpc ) , ( iv ) differential scanning calorimetry ( dsc ) , ( v ) differential thermal analysis ( dta ) , ( vi ) thermogravimetry analysis ( tga ) , ( vii ) zeta potential ( zp ) , ( viii ) elemental analysis ( carbon ( c ) , hydrogen ( h ) , nitrogen ( n ) , and sulfur ( s ) ) , ( ix ) mineral analysis , ( x ) powder x - ray diffraction spectrometry ( pxrd ) , ( xi ) fourier transform infrared spectroscopy ( ft - ir ) , ( xii ) 1d nuclear magnetic resonance ( nmr ) , and ( xiii ) paper chromatography analysis . fruits of manilkara zapota were collected from the forest of rajgamar , district korba , chhattisgarh , in the months of april june and authenticated by professor h. b. singh , niscair , new delhi , india . mucilage was isolated from the seeds using maceration techniques in which seed powder ( 100 g ) was soaked in cold distilled water ( 500 ml ) and slurry was prepared . then slurry was kept aside for a day , then solution was heated on bunsen burner for 1 h ; after one day the mixture was filtered with the help of muslin cloth . the supernatant was collected after centrifugation then double volume of acetone was added in it to precipitate the mucilage . the mucilage was then dried at 40c45c in hot - air oven ( biotech ) and then passed through mesh number 120 and stored in desiccators until used for further studies in powder form . dispersion of sample was prepared in suitable solvent ( water and 0.1 n nacl ) and the relevant information such as density , viscosity , and dielectric constant was added for the solvent in software ( microtrac flex operating software ) . about 3.0 ml sample dispersion was added in sample holder . sample holder made of optical probes which are paired with their opposite electrodes in an insulating sample cell . particle size distribution was determined from the velocity distribution of particles suspended in a dispersing medium , using the principles of dynamic light scattering . the tape was first firmly attached to the stub and the sample powder was scattered carefully over its surface . the stub with the sample was then coated with a thin layer of gold to make the sample conductive . gpc is a technique which enables polymer molecules of different sizes in solution to be separated from one another , such that the large molecules elute first and small molecules elute last . as they emerge from the bottom of the column , they are detected by a differential refractometer . since the molecular size in solution ( hydrodynamic volume ) is related to mw ( molecular weight ) , a picture of the entire mw distribution is obtained quickly and simply . gpc was carried out to estimate molecular weight of the mucilage relative to dextran polysaccharide as standard , using waters alliance model ( waters 2695 separation module with autoinjector ) coupled with waters 2414 refractive index detector ( ri ) . mobile phase was 0.2 m nano3 in water , flow rate was 1.0 ml / min , ultrahydrogel 500 and ultrahydrogel 120 ( 7.8 mm 30 cm 9 um ) were in series . detector and column were operated at 30c , which was started from mw : 5,200 ; 48,600 ; 2,03,000 ; 6,68,000 ; 14,00,000 spectra were processed using empower software . dsc analysis for mucilages was performed using a differential scanning calorimeter ( mettler toledo star system ) . accurately weighed ( 5 mg ) samples were placed into platinum cups and sealed . the temperature range was from 0c to 300c under nitrogen atmosphere at a heating rate of 10c / min . dta is a very popular thermal analysis technique ; it measures endothermic and exothermic transitions as a function of temperature . the analysis mucilage was performed on differential thermal analysis ( stapt , linseis ) in which accurately weighed ( 5 mg ) samples were placed into platinum cups and sealed . the temperature range was from 0c to 240c at a heating rate of 15c / min . tga is a thermal analysis technique for measuring the mass variation in a sample as a function of temperature under a controlled atmosphere . this variation of mass can be positive ( mass gain ) when the sample is subjected to oxidation or corrosion , or else negative ( mass loss ) when part of the sample has been transformed into vapor . thermal stability behavior can be investigated in both conditions : ( 1 ) dynamic , in which the temperature is increased at a linear rate and ( 2 ) isothermal , in which the temperature is kept constant . the analysis of mucilages was done using thermal analyzer ( stapt , linseis , germany ) in which accurately weighed ( 15 mg ) samples were placed into platinum cups and sealed . the temperature range was from 0 to 900c at a heating rate of 15c / min . zp is related to the charge present on the surface or near - surface of a suspended particle . zp was determined using zetatrac ( microtrac ) by measuring the response of charged particles to an electric field . in a constant electric field particlesfloat at a constant velocity . through this velocity and charge zp can be determined . the brownian motion power spectrum is analyzed with the nanotrac controlled reference technique of particle sizing to determine the modulated power spectrum ( mps ) . zp was calculated for mucilage from the mps signal using formula in water and ph dependence of the zeta potential was investigated with the background electrolyte of 0.1 n nacl ( 1 ) = , where is zeta potential , is mobility , is viscosity , and is dielectric constant for water at 25c , zeta potential ( mv ) ~ 12.8 mobility ( / sec / volt / cm ) . elemental compositions ( chns ) were analyzed using elemental analyzer ( elemental , vario ) . accurately weighed 0.5 g of sample was heated to 1150c and corresponding element was determined by using elemental analyzer . the experiments were carried out at 25c under the following conditions : voltage 40 kv , current 30 ma , and 2 angle with scan step time of 10.33 s with specific length of 10 mm . ftir spectra of mucilage were recorded on a ft - ir spectrometer ( thermo scientific ) . nmr spectra of h and c of mucilage were recorded in an nmr ( 400 mhz ) spectrometer ( bruker avance ii 400 ) . the test mucoadhesive agent ( 100 mg ) was dissolved in d2o and chemical shifts were reported in ppm relative to an internal standard tsp ( 3 - trimethylsilylpropionic - 2,2,3,3, - d4 acid , sodium salt , 98 % d ) for h nmr and 1,4 - dioxane ( d 66.67 ppm ) for c spectra . proton nmr spectra were obtained at a base frequency of 400 mhz , with 16 transitions and delay time 1.5 s and for c , the base frequency was 100 mhz , with 3000 scans and delay time 2 s . carbohydrate or sugars occupy a central position in plant metabolism , so the method of their detection and estimation is very important . sugars are conveniently classified into three groups , on the basis of molecular size : the simple monosaccharide 's ( e.g. , glucose and fructose ) and their derivatives , the oligosaccharides , by the condensation of two or more monosaccharide 's units ( e.g. , sucrose ) , and the polysaccharides which consist of long chains of monosaccharide 's units , joined head to tail , either as straight chains or without branching . the samples were prepared in distilled water for paper chromatography . the paper chromatography analysis was performed using n - butanol : acetic acid : water ( 4 : 1 : 1 ) as solvent system with using arabinose , fructose , mannose , rhamnose , and xylose as reference standards . the average particle size as determined by zetatrac particle size analyzer indicated that obtained mucilages were in fine particle size and average range was obtained as 500551 nm diameters . the particles are mostly seen as aggregates of irregular shapes and dimensions which were fibrous in nature . the molecular weight of mucilages were determined by gel permeation chromatography and expressed as the dextran polysaccharide equivalent molecular weight . the computed average molecular weights , ( mw ) , number of average molecular weight , ( mn ) , and polydispersity ( mw / mn ) are tabulated in table 1 . dsc has emerged as powerful physical tools to monitor physical and chemical changes that occur in the gum during thermal processing and these methods yield curves that are unique for a given gum . the outcome of differential scanning calorimetry ( dsc ) ; analysis of mucilage revealed that the glass transition temperature is 138c . the major intense peak recorded in the dsc thermograms is an endothermic transition ( at around 200c ) followed by weaker exotherm ( s ) . tga is a simple and accurate method for studying the decomposition pattern and the thermal stability of polymers . table 2 gives the details of thermal behavior according to the primary thermograms and derivative thermograms of mucilages . the representative plot results of thermogravimetric analysis carried out on the mucilages under lean oxygen ( 5 % oxygen in nitrogen ) atmosphere are shown in figure 4 . the details of thermal behavior and thermal stability data according to the primary thermograms and derivative thermograms for the gum showed that heating at a rate of 10c per minute from 0c to a maximum of 900c resulted in two mass loss events . the results of elemental composition and heavy metal characterization are tabulated in table 3 . the elemental analysis study showed that the isolated mucilage had certain percentage of carbon , nitrogen , sulphur , and hydrogen , while toxic heavy metal like arsenic , lead , cadmium , and mercury were absent . the zp measurement was performed to collect information on the stability and charge behavior of the polymer . the zp of mucilage in aqueous medium ( water ) was recorded to be 18.05 mv and in 0.1 n nacl was recorded to be 5.15 mv , respectively . the result indicated that no characteristic peaks were observed in the spectrum , indicating that the mucilages were completely amorphous in nature . the spectra of mucilage showed band occurring at 3559.78 cm results from the presence of amide n h & c = o stretch and amine n h . the peak obtained at 3470.093418.01 cm results from the presence of hydroxyl ( oh and co ) groups . the peak obtained at 2884.672819.09 cm results from stretching modes of the alkyl c h stretch , carboxylic acid c = o & o h stretch , and methylene ( ch2 ) c h stretch . the peak obtained at 2167.121660.78 cm results from stretching mode of the alkenyl c h & c = c stretch and amide n h & c = o stretch . the interpretation of h and c nmr spectra analysis was done using chemix school software and was represented in figures 7 and 8 . the h and c nmr spectra of mucilage indicated presence of certain sugar composition such as signals of h nmr spectra between d 3.58 d 3.40 ppm can be attributed to ch and oh group of rhamnose , mannose and arabinose . the signal at d 67.9 ppm , 72.2 ppm , and d 72.3 ppm of c nmr spectra can be attributed to ch group of rhamnose and mannose . the rf value of standards arabinose , fructose , mannose , rhamnose , and xylose matched with the obtained rf values of test substances ( mucilage ) . the traditional concept of the excipients as any component other than the active substance has undergone a substantial evolution from an inert and cheaper vehicle to an essential constituent of the formulation . excipients are any components other than the active substances intentionally added to formulation of a dosage form . micromeritics involve the study of small particles and the order of a few micron sizes . particle size analysis involves the characterization of individual particles , particles size distribution , and powders . particle size also previews the degree of densification , which could occur during tableting which was further also confirmed by sem analysis . microscopy is a major tool for the characterization of polymer material ultrastructure . in case of drug delivery system , such imaging technique is used to examine the detail shape , size , and distribution of polymeric micro - and nanoparticles , as well as interaction with biological environment . the sem results of the present study suggest that hydration capacity of mucilage depends on the surface property as presented in powder xrd studies . it was reported earlier that particle size and specific surface area influence the hydration behavior of gums , which in turn influence their intrinsic viscosity and molecular mass . further , wang experimentally reported that particle size influenced the hydration kinetics and molecular mass of guar gum which is a galactomannan - rich tree gum . polymer molecular weight determination is important because it determines many physical properties such as the temperatures for transitions from liquids to wax to rubber to solids and mechanical properties such as stiffness , strength , viscoelasticity , toughness , and viscosity . mw / mn ) is used as a convenient measure of the range of molecular weight present in a distribution and is in the range of 1.57.0 for natural polysaccharide gums . if the molecular weight is too low , the transition temperatures and the mechanical properties will generally be too low for the polymer material to have any useful commercial applications . for a polymer to be useful it must have transition temperatures to wax or liquids that are above room temperature and it must have mechanical properties sufficient to bear design loads . further , molecular weight is also a physical property of compound , which helps in standardization . whenever a polymer undergoes a phase transition such as melting or a glass transition from the rigid glass state to the soft rubber state , the temperature trends to remain constant while energy is taken in to the system . dsc and dta are essentially techniques that compare the difference between the energy acquired or released by a sample and a suitable reference as a function of temperature or time , while the sample and reference are subjected to a controlled temperature rise . the result of dsc and dta revealed that the isolated mucilage from seeds has good stability . dehydration , depolymerization , and pyrolytic decomposition are involved in dsc and dta at high temperature stages and resulted in the formation of h2o , co , and ch4 . however , because of the difference in structures and functional groups , either the degradation routes or the resulting fragments will be different . therefore , thermal scission of the carboxylate groups and evolution of co2 from the corresponding carbohydrate backbone may be a probable mechanism for the thermal transitions . the early minor weight loss in samples is attributed to the loss of adsorbed and structural water of biopolymers as related by other authors or due to the desorption of moisture as hydrogen bound water to the saccharide structure . the second weight loss event may be attributed to the polysaccharide decomposition and is described by a weight loss . the weight loss onset ( representing the onset of oxidation or decomposition ) of polymer suggests that mucilages have good thermal stability . elemental analysis is a process where a sample of some materials ( e.g. , soil , minerals , and chemical compounds ) is analyzed for its elemental composition such as carbon , hydrogen , nitrogen , and sulphur . elemental analysis can be qualitative ( determining what elements are present ) , and even it can be quantitative . the elemental and heavy metal analysis showed presence of certain percentage of carbon , nitrogen , sulphur , and hydrogen and absence of heavy metals in mucilages . further study also suggested the presence of s - containing protein and amino acids and also confirms the formation of bond ( primary strong covalent bonds , weak secondary hydrogen bond , and vander waal 's forces ) of mucilage with mucosa in a short duration of time . electrokinetic measurement is one way to study complex surface chemical exchange processes at the clay mineral surface / liquid interface . all electrokinetic phenomena are related to the development of electrical double layer at the particle / electrolyte interface . the zeta potential is defined as the potential of shear plane of the particle when it moves in liquid . the results of zp studies suggested that the mucilages are ionic in nature and attributed to the presence of uronic acids as similar to what was previously reported by mohammadifar et al . for gum tragacanth which is uronic acid - rich gum . polarity of mucilage may be due to the presence of oh group , which is readily available for the formation of hydrogen bonds on the interface of reinforced systems . however , plant mucilages are covered with pectin and waxy substances , thus hindering the hydroxyl groups ( oh ) from reacting with polar matrices and deteriorate adhesion , but polar structure is only responsible for hydrophilic behavior of mucilage . for high adhesion forces , it is necessary to have polar functional groups , but swelling processes should be prevented . according to kanamaru , the extent of mucus adsorption is proportional to the absolute values of the positive zeta potential of mucilage and negative zp of mucus glycoprotein . shashikant reported that the significant difference in zp of a polymer may be obtained due to change in environment , that is , particles decomposition which yield small charge and surface properties of particles . it was concluded that conductivity of any solution is a function of electrolytes or ions and charge in ionic concentration is known to increase conductivity . the conductivity and dielectric constant often increase with thermal and electrical stress . this also finds support in the fact that there is concomitant shift in uv and ir spectra . taking account of earlier studies it can be believed that the zp caused huge impact on properties of mucilage . the powder x - ray diffraction is a useful method for investigating the arrangement of atom and molecules within the material . if there is an orderly arrangement of substructure within the material with repeat distances of a similar magnitude to the wavelength of light used , interference patterns are produced , and such patterns provide information on geometry of polymer structure . powder xrd analysis of mucilage sample showed no characteristic sharp peaks in the spectrum and indicated that the mucilage is completely amorphous in nature . natural gums , such as arabic , guar gum , and karaya gum , also show amorphous nature . ftir spectrometry has been extensively applied to characterize the polymer 's molecular and material structure . characterization using ftir spectroscopy often results in the identification of functional groups and the modes of their attachment to polymer backbone . the broad band occurring at 35003200 cm results from the presence of hydroxyl ( oh ) groups . natural gums usually contain fractions of sugar acid units which would usually impart a weakly anionic character to the gum macromolecule . absorption bands around 1618 and 1430 cm are typical of carboxylate groups of the galacturonic acid residues as reported by okafor et al . the region between 1500 and 1800 cm is typically used to detect presence of carboxylic groups . also , absorption peaks at 1740 cm and 1258 cm are typical of acetyl groups . the wave numbers between 800 and 1200 cm represents the finger print region for carbohydrates . nmr is the most powerful tool for the study of microstructure and chain configuration of polymers , both in solution and in solid state . the importance of nmr as a technique is from the fact that nmr signals can be assigned to specific atoms along the polymer backbone and side chains . the h nmr spectrum for mucilage showed few singlet at high field ( d 1.1785 ppm ( s ) , d 1.9559 ppm ( s ) ) , which is related to the environments of methyl groups of rhamnose and the protons linked to c - 6 ( d 3.65 , d 3.70 ppm ) and c - 4 of galactose ( d 3.98 , 4.28 ppm ) , respectively , and this suggests the existence of different galactose derivatives . the anomeric protons have been assigned to - sugar residues ( d 4.924.96 ppm ) and the - sugar residue ( d 5.15.3 ppm ) , as reported earlier by agrawal . the two closely neighbored signals observed in the h nmr spectrum of mucilage ( d 4.02 and d 3.84 ppm ) were assigned to h - 1 of - glucose . the h nmr spectrum showed that crowded narrow region between 3 to 5 ppm is typical of polysaccharides and confirms the presence of many similar sugar residues . the signals between 3.1 and 4.3 ppm can be assigned to nonanomeric protons ( h2h6 ) , while signals between 4.3 and 4.8 , and 4.9 and 5.5 ppm arise from - anomeric and - anomeric protons , respectively . c nmr spectra of mucilages gave line widths which are typical of an amorphous natural polymer with broad band signals . there are resonance spectra due to the methyl group of rhamnose ( d 16.67 ppm ) as reported earlier by martnez et al . . plant gums and mucilages are an important group of plant constituents with pharmaceutical and technical uses . the separation and sensitive determination of various carbohydrates are currently of great interest in nutrition , medical cell biology , and biotechnology research . carbohydrates are difficult to analyze because they are very polar compounds , exhibit similar structural characteristics , and do not have a suitable chromophore . the paper chromatography analysis was performed in order to check the available carbohydrates in mucilage . the result obtained from 1d nmr , ftir , and paper chromatography studies indicated the presence of arabinose , fructose , mannose , rhamnose , xylose , and glucose . the result obtained from the study indicated similar rf values to the standard available data for sugars . according to lee , arabinose is reported to be a free , but minor , sugar component of onions , grapes , strawberries , commercial beer , corn , and alfalfa . the overall findings of the study indicated that mucilage isolated from the seeds have an inherent property which can be used in various dosage forms on modification . the pxrd and sem revealed that mucilage is amorphous in nature which indicated that wet granulation technology will be more suitable for dosage formulation . the thermal stability study by dsc , dta , and tga showed that mucilage had good thermal stability . ftir , solid 1d h , and c nmr and paper chromatography confirmed presence of nonreducing sugars . all these results demonstrate that mucilage is a useful pharmaceutical aid and can be used for effectively controlling the release of drugs from the designed matrix systems .\noutput:\n" }, { "from": "agent", "value": "mucilage isolated from seeds of manilkara zapota ( linn . ) p. royen syn . is a plant growing naturally in the forests of india . this mucilage is yet to be commercially exploited , and characterized as polymer . various physicochemical methods like particle size analysis , scanning electron microscopy , thermal analysis , gel permeation chromatography , x - ray diffraction spectrometry , zeta potential , fourier transform infrared spectroscopy , and nuclear magnetic resonance spectroscopy have been employed to characterize this gum in the present study . particle size analyses suggest that mucilage has particle size in nanometer . scanning electron microscopy analysis suggests that the mucilage has irregular particle size . the glass transition temperature of the gum was observed to be 138c and 136c by differential scanning calorimetry and differential thermal analysis , respectively . the thermogravimetric analysis suggested that mucilage had good thermal stability . the average molecular weight of mucilage was determined to be 379180 , by gel permeation chromatography , while the viscosity of mucilage was observed to be 219.1 cp . the x - ray diffraction spectrometry pattern of the mucilage indicates a completely amorphous structure . elemental analysis of the gum revealed the contents of carbon , hydrogen , nitrogen , and sulfur to be 80.9 ( % ) , 10.1 ( % ) , 1.58 ( % ) , and 512 ( mg / kg ) , respectively . mucilage had specific content of calcium , magnesium , potassium , lower concentrations of aluminum , cadmium , cobalt , lead , and nickel . the major functional groups identified from ft - ir spectrum include 3441 cm1 ( oh ) , 1660 cm1 ( alkenyl c h & c = c stretch ) , 1632 cm1 ( coo ) , 1414 cm1 ( coo ) , and 1219 cm1 ( ch3co ) . analysis of mucilage by paper chromatography and 1d nmr , indicated the presence of rhamnose , xylose , arabinose , mannose , and fructose ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we present an interesting case of bilateral retinitis pigmentosa ( rp ) - associated cystoid macular oedema that responded on two separate occasions to intravitreal injections of aflibercept , despite previously demonstrating only minimal response to intravitreal ranibizumab . this unique case would support a trial of intravitreal aflibercept for the treatment of rp - associated cystoid macular oedema . a 38 - year - old man from dubai , united arab emirates , presented to the uk with a 3 - year history of bilateral rp - associated cystoid macular oedema . previous treatment with topical dorzolamide , oral acetazolamide , and intravitreal ranibizumab had demonstrated only minimal reduction of cystoid macular oedema . following re - confirmation of the diagnosis by clinical examination and optical coherence tomography imaging , bilateral loading doses of intravitreal aflibercept were given . after 6 months , the patient was treated with intravitreal ranibizumab due to re - accumulation of fluid and the unavailability of aflibercept in dubai . only minimal reduction of central macular thickness was observed . once available in dubai , intravitreal aflibercept was administered bilaterally with further reduction of central macular thickness observed . this is the first case report to demonstrate a reduction of rp - associated cmo following intravitreal aflibercept , despite inadequate response to ranibizumab on two separate occasions . aflibercept may provide superior action to other anti - vegf medications due to its intermediate size ( 115 kda ) and higher binding affinity . this is worthy of further investigation in a large prospective cohort over an extended time to determine the safety and efficacy of intravitreal aflibercept for use in this condition . retinitis pigmentosa ( rp ) is the most prevalent inherited retinal disease ( ird ) , with ird now representing the commonest cause of visual impairment registration in the working age population and the second commonest in childhood in the uk . typical symptoms of rp include nyctalopia , photopsia , and progressive visual field loss ; however , vision can also be affected by cataracts and / or cystoid macular oedema ( cmo ) . around 20 % of rp patientssuggested mechanisms include : anti - retinal antibodies , retinal pigment epithelium dysfunction , muller cell oedema , and vitreous traction . many treatments have been attempted for rp - associated cmo , including grid laser , vitrectomy , oral lutein , intravitreal dexamethasone , intravitreal triamcinolone , topical carbonic anhydrase inhibitors , oral carbonic anhydrase inhibitors , oral corticosteroids , topical non - steroidal anti - inflammatory medication , and topical steroid . this , together with several side effects of these medications that markedly restrict their use , has led to the search to find alternative therapies that are both well tolerated and are more consistently effective . intravitreal anti - vascular endothelial growth factor ( anti - vegf ) medication is now licenced for use within the uk for cmo secondary to macular degeneration , diabetic retinopathy , and retinal vein occlusion . while the pathogenesis of rp - associated cmo is still unclear , it is believed that vegf may play a role in the development of cmo . limited data has been published regarding the use of intravitreal anti - vegf medication for rp - associated cmo . observed improvement of visual acuity and macular thickness in a patient with refractory rp - associated cmo taking oral acetazolamide , 1 month following a single injection of intravitreal pegaptanib ( macugen ; eyetech pharmaceutical , inc . melo et al . observed no improvement in 2 patients with rp - associated cmo treated with a single injection of intravitreal bevacizumab ( avastin ; genentech , south san francisco , calif . , documented improvement of macular thickness and visual acuity in all 13 eyes of 7 patients . treated 15 eyes with rp - associated cmo with intravitreal ranibizumab and compared them with 15 eyes of similar patients who refused treatment . a significant improvement in macular thickness was observed in those patients treated with intravitreal ranibizumab . in a recent case report , a single unilateral intravitreal injection of aflibercept was given to a patient with rp - associated cmo . improvement in both visual acuity and macular thickness was seen at 1 month post - injection as well as maintenance of this improvement documented at 6 months . aflibercept is a recombinant fusion protein consisting of portions of the extracellular domains of human vegf receptors 1 and 2 fused to the fc portion of human igg1 . this unique design is what sets aflibercept apart from other intravitreal anti - vegf medications by enabling its action as a decoy receptor . in august 2013 , a 38 - year - old man from dubai , united arab emirates , was seen by a medical retina specialist in the uk . he was previously diagnosed with autosomal recessive rp in dubai and bilateral cmo had been documented over the last 3 years . the patient had undergone uncomplicated bilateral cataract surgery with the insertion of posterior chamber intraocular lenses in 2004 . he had previously received topical dorzolamide and a 3 - week trial of oral acetazolamide ( diamox ) 250 mg three times per day , with no significant improvement in the degree or extent of cmo . , usa ) had been performed once a month for 3 months in dubai in 2013 with only minimal response observed . at the time of the consultation in the uk , the patient was no longer receiving topical or oral treatment for cmo . on examination , bcva was 6/18 in the right eye and 6/36 in the left eye . fundoscopy revealed bilateral dense bone spicules , bilateral cmo , attenuated retinal vessels , and pale optic discs . spectral domain optical coherence tomography ( sdoct ) showed marked bilateral cmo with central macular thickness ( cmt ) of 394 and 414 m in the right and left eye , respectively ( fig 1a , e ) . the anti - vegf medication selected for use in this patient was aflibercept ( eylea ; regeneron pharmaceuticals , inc . , this was due to there being only a minimal response observed following treatment with ranibizumab as well as consideration that its effects may be longer lasting than other anti - vegf medication . the risks and benefits of treatment with aflibercept together with its off - label use were discussed with the patient . it was also highlighted that there was a limited evidence base for its usage in rp - associated cmo . informed consent was taken and bilateral intravitreal injections of 0.05 ml aflibercept ( 40 mg / ml ) given via standard aseptic technique . one month after treatment , bcva improved to 6/12 in the right eye but remained 6/36 in the left eye . sdoct revealed markedly less cmo in both eyes , with cmt of 263 and 243 m in the right and left eye , respectively ( fig 1b , f ) . one month after his second injection of aflibercept , bcva remained at 6/12 in the right eye and 6/36 in the left eye . at this visit , cmt was 268 and 239 m in the right and left eye , respectively ( fig 1c , g ) . the patient then returned to the united arab emirates where he was seen by a medical retina specialist in dubai , in december 2013 . sdoct revealed a similar level of cmo bilaterally ( fig 1d , h ) , despite his last aflibercept injection being 8 weeks prior . cmt was recorded as 253 and 224 m in the right and left eye , respectively . as the patient was stable , the decision was taken not to treat with an alternative anti - vegf , since aflibercept was due to be made available for use in dubai from january 2014 . unfortunately , there was an unexpected delay in aflibercept being made available for use in dubai . in march 2014 ( 5 months after the patient 's last injection of aflibercept ) , bcva was 6/18 in the right eye and 6/36 in the left eye . sdoct revealed a significant increase of cmo bilaterally , with cmt of 385 and 434 m in the right and left eye , respectively ( fig 2a , c ) . in order not to delay treatment any further , the decision was taken to perform 3 monthly loading doses of ranibizumab bilaterally . the response to ranibizumab was markedly less pronounced compared to aflibercept . in may 2014 , bcva remained at 6/18 in the right eye and had decreased to 6/48 in the left eye . sdoct revealed bilateral cmo , with cmt of 304 and 342 m in the right and left eye , respectively ( fig 2b , d ) . the decision was taken not to perform further injections of ranibizumab . in august 2014 , sdoct measured 452 and 513 m in the right and left eye , respectively ( fig 3a , e ) . fortunately , aflibercept became available for use in dubai , and the patient received treatment with 3 monthly loading doses of aflibercept bilaterally . bcva had improved to 6/18 in the right eye and 6/36 in the left eye . sdoct showed a marked reduction in cmo ( fig 3b , f ) , measuring 248 and 226 m in the right and left eye , respectively . the patient continued to receive aflibercept injections in january 2015 , march 2015 , june 2015 , and september 2015 and cmt remained stable ( fig 3c , g ) . in september 2015 , bcva was 6/15 in the right eye , 6/36 in the left eye , with stable cmt of 250 and 194 m in the right and left eye , respectively ( fig 3d , h ) . the use of medication , such as carbonic anhydrase inhibitors , has demonstrated inconsistent efficacy and unwanted side effects . fda approval of anti - vegf medication has now extended to include cmo secondary to age - related macular degeneration , diabetic retinopathy , and retinal vein occlusion . while the pathogenesis of rp - associated cmo is not entirely understood , vegf may play a role in the formation of rp - associated cmo thereby representing a potential target for treatment . rp is not an ischaemic condition and if anything , the natural bone spicule formation secondary to photoreceptor cell death results in an overall reduction of oxygen consumption by the retina . we hypothesise that a localised source of vegf produced , for example , by muller cells under pathological conditions contributes to cmo formation whilst also explaining why it is rare to find reports of peripheral neovascularisation in rp . this is the first case report to demonstrate a reduction of rp - associated cmo following intravitreal aflibercept , despite inadequate response to ranibizumab . aflibercept may provide superior action to other anti - vegf medications due to its intermediate size ( 115 kda ) and higher binding affinity . this is worthy of further investigation in a large prospective cohort over an extended time to determine the safety and efficacy of aflibercept for use in this condition . funding was not received to write this case report ; however , bayer plc will be approached to cover the publication costs should this article be accepted . the authors s.a.s . and m.m . declare that they are currently being funded by bayer plc . to set up a phase ii exploratory trial at moorfields eye hospital , london , uk , to review the safety and efficacy of aflibercept for rp - associated cmo .\noutput:\n" }, { "from": "agent", "value": "backgroundwe present an interesting case of bilateral retinitis pigmentosa ( rp ) - associated cystoid macular oedema that responded on two separate occasions to intravitreal injections of aflibercept , despite previously demonstrating only minimal response to intravitreal ranibizumab . this unique case would support a trial of intravitreal aflibercept for the treatment of rp - associated cystoid macular oedema.case presentationa 38 - year - old man from dubai , united arab emirates , presented to the uk with a 3 - year history of bilateral rp - associated cystoid macular oedema . previous treatment with topical dorzolamide , oral acetazolamide , and intravitreal ranibizumab had demonstrated only minimal reduction of cystoid macular oedema . following re - confirmation of the diagnosis by clinical examination and optical coherence tomography imaging , bilateral loading doses of intravitreal aflibercept were given . central macular thickness reduced and the patient returned to dubai . after 6 months , the patient was treated with intravitreal ranibizumab due to re - accumulation of fluid and the unavailability of aflibercept in dubai . only minimal reduction of central macular thickness was observed . once available in dubai , intravitreal aflibercept was administered bilaterally with further reduction of central macular thickness observed . visual acuity remained stable throughout.conclusionsthis is the first case report to demonstrate a reduction of rp - associated cmo following intravitreal aflibercept , despite inadequate response to ranibizumab on two separate occasions . aflibercept may provide superior action to other anti - vegf medications due to its intermediate size ( 115 kda ) and higher binding affinity . this is worthy of further investigation in a large prospective cohort over an extended time to determine the safety and efficacy of intravitreal aflibercept for use in this condition ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: gingival recession is the displacement of the gingival margin apical to the cemento - enamel junction with oral exposure of the root surface . gingival recession may occur on one or all surfaces of a tooth and may affect a localized area or have a more generalized distribution within a dentition . although many conditions or behavioral habits are associated with an increased risk for gingival recession , the common etiological factor appears to be the development of inflammation within the gingival connective tissue . this inflammation is thought to result in the degeneration of gingival connective tissue , this eventually undermines the gingival tissues , resulting in shrinkage and recession of the gingival tissues . the resulting exposure is not aesthetically pleasing and may lead to root hypersensitivity and root caries . since mid-20 century , different techniques like free autogenous grafts , pedicle grafts including rotational flaps , coronally advanced flaps ( cafs ) , semilunar flaps have been advocated to cover denuded root surfaces . combination techniques using autogenous or allograft and guided tissue regeneration membranes were developed later to correct muco - gingival defects . a recent innovation in dentistry is the use of second - generation platelet concentrate which is an autologous platelet - rich fibrin ( prf ) gel with growth factors and cicatricial properties for root coverage procedures . therefore , the present research was undertaken to study the additional benefits of prf when used along with a caf . fifteen subjects aged between 18 and 35 years who visited the outpatient department of periodontics , st . joseph dental college and hospital , eluru , andhra pradesh , and having bilateral buccal miller 's class i and class ii gingival recessions with no radiographic interdental bone loss were selected for the study . the benefits and drawbacks of the study explained to the patients and upon signing an informed consent , the patients were recruited for the study . exclusion criteria included : patients with known systemic diseases or immune deficiency , patients on medication , psychiatric disorders and pregnancy , history of smoking , inability or unwillingness to complete the trial and who are participating in another clinical trial . patients with known systemic diseases or immune deficiency , patients on medication , psychiatric disorders and pregnancy , inability or unwillingness to complete the trial and who are participating in another clinical trial . a randomized split mouth clinical design was used with 30 sites in 15 patients ( 2 sites in each patient ) and the selected sites were divided into two groups which were categorized as group - i ( control group - 15 sites were treated with caf alone ) and group - ii ( test group - 15 sites treated with coronally advanced flap + platelet - rich fibrin membrane ) . all subjects received clinical periodontal examination by a single examiner to avoid inter - examiner variability . the following periodontal parameters like plaque index ( loe and sillness 1962 ) , recession depth ( rd ) , clinical attachment level ( cal ) , width of keratinized gingiva ( wkg ) , and the percentage of root coverage were recorded at base line , 1 month , 3 months , and 6 months postoperatively using william 's periodontal probe [ figures 1 and 2 ] . the rd was measured at mid - facial region of the tooth from cej to the free gingival margin . the clinical attachment level was measured from a fixed reference point ( cej ) to the base of the sulcus using customized stent . the wkg was determined by subtracting the rd from the cej - mgj ( mucogingival junction ) . two weeks postoperative view 6 month postoperative preoperatively , 10 ml of intravenous blood was collected in a syringe , later transferred into a test tube and centrifuged immediately without the addition of anticoagulant at 3000 revolutions per minute for 10 minutes . the absence of anticoagulant initiates the activation of platelets when they come in contact with the walls of the test tube . top most layer consisting of acellular plasma , prf clot in the middle , red blood cells at the bottom [ figure 3 ] . prf clot was separated from other two layers and prf was obtained in the form of a membrane by squeezing out the fluids in the fibrin clot [ figure 4 ] . centrifuged blood sample platelet - rich fibrin membrane thorough scaling and root planing was done on the selected patients after initial examination . one week after phase i therapy , only those patients who maintained optimum oral hygiene were subjected to surgical procedure after recording all the baseline measurements . two gingival recession sites in each patient were randomly assigned as either test site or control site by flipping the coin . in control sites , the surgical site was prepared by placing two vertical incisions beyond the mucogingival junction followed by placing an internal bevel incision . mucoperiosteal flap was raised and coronally advanced so that its gingival margin lies 1 mm coronal to the cementoenamel junction and sutured using sling sutures . the surgical area was protected using a non - eugenol dressing ( coe - pack , gc america inc . the surgical sites preparation was similar to control sites and the prepared prf membrane was placed over the denuded root surface just below the cej [ figure 7 ] . preoperative site showing miller 's class i recession prepared surgical site prf membrane placed over the site after surgery , postoperative instructions were given including a recommendation to refrain from mechanical cleaning on the surgical areas and all the patients were prescribed with cap . ibuprofen 400 mg three times a day ( 7 days postoperative ) and 0.2 % chlorhexidine mouthwash twice daily , for a period of 1 month . all 15 patients who were included in the study received the treatment and turned up regularly for re - evaluation . the significance of the difference within and between groups before and after treatment was evaluated with the paired - samples t test . preoperatively , 10 ml of intravenous blood was collected in a syringe , later transferred into a test tube and centrifuged immediately without the addition of anticoagulant at 3000 revolutions per minute for 10 minutes . the absence of anticoagulant initiates the activation of platelets when they come in contact with the walls of the test tube . top most layer consisting of acellular plasma , prf clot in the middle , red blood cells at the bottom [ figure 3 ] . prf clot was separated from other two layers and prf was obtained in the form of a membrane by squeezing out the fluids in the fibrin clot [ figure 4 ] . centrifuged blood sample platelet - rich fibrin membraneone week after phase i therapy , only those patients who maintained optimum oral hygiene were subjected to surgical procedure after recording all the baseline measurements . two gingival recession sites in each patient were randomly assigned as either test site or control site by flipping the coin . in control sites , the surgical site was prepared by placing two vertical incisions beyond the mucogingival junction followed by placing an internal bevel incision . mucoperiosteal flap was raised and coronally advanced so that its gingival margin lies 1 mm coronal to the cementoenamel junction and sutured using sling sutures . the surgical area was protected using a non - eugenol dressing ( coe - pack , gc america inc . the surgical sites preparation was similar to control sites and the prepared prf membrane was placed over the denuded root surface just below the cej [ figure 7 ] . preoperative site showing miller 's class i recession prepared surgical site prf membrane placed over the site after surgery , postoperative instructions were given including a recommendation to refrain from mechanical cleaning on the surgical areas and all the patients were prescribed with cap . ibuprofen 400 mg three times a day ( 7 days postoperative ) and 0.2 % chlorhexidine mouthwash twice daily , for a period of 1 month . all 15 patients who were included in the study received the treatment and turned up regularly for re - evaluation . the significance of the difference within and between groups before and after treatment was evaluated with the paired - samples t test . the mean plaque index score at baseline was 2.040.37 which was reduced to 0.520.37 at 3 months and 0.200.11 at 6 months post surgically showed a statistically significant ( p 0.05 ) mean reduction in plaque index scores . the mean recession depth in group - i ( control site ) at baseline was 3.441.21 mm , after 1 , 3 , and 6 months which was reduced to 2.441.15 , 1.440.96 , 1.130.72 mm , respectively [ tables 13 ] . the mean recession depth in group - ii ( test site ) at baseline was 3.441.09 mm , which was reduced to 2.311.01 , 1.130.89 , 0.000.00 mm at 1 , 3 , and 6 months postoperatively , the difference was statistically significant [ tables 13 ] . comparison of parameters at 1 month postoperatively comparison of parameters at 3 months postoperatively comparison at 6 months postoperatively an intergroup comparison of mean reduction in recession depth at 1 and 3 months showed a p value of 0.672 and 0.305 , respectively , which is statistically not significant ( p 0.05 ) . but , a similar comparison at 6 months post - operatively showed a p value of 0.001 which is statistically significant [ tables 1 and 3 ] . the mean clinical attachment level in group - i at baseline was 4.691.25 mm which was reduced to 3.501.21 , 2.440.96 , 2.000.89 mm post surgically at 1 , 3 , 6 months , respectively , in group - ii at baseline was 4.751.29 mm which was reduced to 3.311.20 , 2.131.02 , 1.000.00 mm post surgically at 1 , 3 , 6 months , respectively , showing a statistically significant mean reduction in clinical attachment level ( p 0.05 ) [ tables 13 ] . the intergroup comparison at 1 and 3 months showed a p value of 0.582 and 0.377 , respectively , which is statistically not significant ( p 0.05 ) . similarly , at 6 months a p value is 0.002 , which is statistically significant ( p 0.05 ) [ tables 1 and 3 ] . both the groups showed an increase in the mean width of keratinized gingiva from baseline to 6 months . a comparison of mean width of keratinized gingiva between the two groups from baseline to 1 , 3 , and 6 months postoperatively showed a p value of 0.033 , 0.003 , and 0.031 respectively which was statistically significant [ table 3 , graph 1 ] . comparison of mean width of keratinized gingiva the mean % reduction in root coverage in group - i and group - ii at 6 months postoperatively was 68.4417.42 , 100.000.00 respectively and showed a p value of 0.00 which is statistically significant ( p 0.05 ) [ table 4 ] . the mean plaque index score at baseline was 2.040.37 which was reduced to 0.520.37 at 3 months and 0.200.11 at 6 months post surgically showed a statistically significant ( p 0.05 ) mean reduction in plaque index scores . the mean recession depth in group - i ( control site ) at baseline was 3.441.21 mm , after 1 , 3 , and 6 months which was reduced to 2.441.15 , 1.440.96 , 1.130.72 mm , respectively [ tables 13 ] . the mean recession depth in group - ii ( test site ) at baseline was 3.441.09 mm , which was reduced to 2.311.01 , 1.130.89 , 0.000.00 mm at 1 , 3 , and 6 months postoperatively , the difference was statistically significant [ tables 13 ] . comparison of parameters at 1 month postoperatively comparison of parameters at 3 months postoperatively comparison at 6 months postoperatively an intergroup comparison of mean reduction in recession depth at 1 and 3 months showed a p value of 0.672 and 0.305 , respectively , which is statistically not significant ( p 0.05 ) . but , a similar comparison at 6 months post - operatively showed a p value of 0.001 which is statistically significant [ tables 1 and 3 ] . the mean clinical attachment level in group - i at baseline was 4.691.25 mm which was reduced to 3.501.21 , 2.440.96 , 2.000.89 mm post surgically at 1 , 3 , 6 months , respectively , in group - ii at baseline was 4.751.29 mm which was reduced to 3.311.20 , 2.131.02 , 1.000.00 mm post surgically at 1 , 3 , 6 months , respectively , showing a statistically significant mean reduction in clinical attachment level ( p 0.05 ) [ tables 13 ] . the intergroup comparison at 1 and 3 months showed a p value of 0.582 and 0.377 , respectively , which is statistically not significant ( p 0.05 ) . similarly , at 6 months a p value is 0.002 , which is statistically significant ( p 0.05 ) [ tables 1 and 3 ] . both the groups showed an increase in the mean width of keratinized gingiva from baseline to 6 months . a comparison of mean width of keratinized gingiva between the two groups from baseline to 1 , 3 , and 6 months postoperatively showed a p value of 0.033 , 0.003 , and 0.031 respectively which was statistically significant [ table 3 , graph 1 ] . the mean % reduction in root coverage in group - i and group - ii at 6 months postoperatively was 68.4417.42 , 100.000.00 respectively and showed a p value of 0.00 which is statistically significant ( p 0.05 ) [ table 4 ] . studies on this surgical challenge is mostly concerned with the treatment of miller 's class i and ii recession defects . fifteen systematically healthy subjects aged between 18 and 35 years presenting with identical bilateral isolated miller 's class i and ii were enrolled into the study . rd , cal , and wkg were measured at baseline , 1 , 3 , 6 months at test and control sites . caf is a predictable procedure to treat miller 's class i mucogingival defects and initial gingival thickness was the most significant factor associated with complete root coverage by analyzing the factors like recession depth , probing depth , width of keratinized gingiva , clinical attachment level , and gingival thickness . therefore , this study is conducted to see the additional benefits of using prf along with the standard procedure of caf which gives the more predictable results . the autologous prf clot was used initially in implant surgery to improve bone healing . due to the lack of scientifically proven clinical benefit , the homogeneous fibrin network is considered by the promoters to be a healing biomaterial and is commonly used in implant and plastic periodontal surgery procedures to enhance bone regeneration and soft tissue wound healing . compared to prp , there is very little literature available about the biologic properties of prf . however , it contains platelets , growth factors , and cytokines that may enhance the healing potential of bone as well as soft tissues . the percentage of root coverage for test group at 6 months is statistically significant when compared to the control group . sling sutures were used in this study to allow stabilization of the flap margin at or above the cementoenamel junction during the first 2 weeks of wound healing similar to theprevious study . the addition of prf as a membrane to caf showed an increase in width of keratinized gingiva and a decrease in clinical attachment loss , recession depth , which was statistically significant at 6 months . this in accordance with study done by jankovic et al . , who evaluated and compared the clinical effectiveness of platelet rich plasma and connective tissue graft in the treatment of gingival recession . in studies evaluating the coronally repositioned flaps together with free connective grafts by wennstorm et al . , pini prato and lee et al . , it has been reported that long - term increase in width of keratinized gingiva associated with an apical shift of the mucogingival junction . in our study , a significant increase in the width of keratinized gingiva was observed at all periods ( 1,3,6 months ) compared to the baseline values for both the study groups . in our study , a significant gain in cal was observed in both the groups . these outcomes are also in agreement with literature reports for the treatment of gingival recession with a connective tissue graft and caf . the secretion profile of three isoforms of cytokines [ platelet - derived growth factor - bb ( pdgf - bb ) , transforming growth factor -1 ( tgf - 1 ) and insulin growth factor - 1 ( igf - 1 ) ] within the different parts of the prf collection tube and a whole range of concentrated platelet rich plasma were studied . from their comparative biochemical analysis , authors came to the conclusion that prf consists of an intrinsic assembly of cytokines , glycemic chains , and structural glycoproteins enmeshed in a slowly polymerized fibrin network having synergistic effects on healing processes - 1 ) and insulin growth factor - 1 ( igf - 1 ) ] within the different parts of the prf collection tube and a whole range of concentrated platelet rich plasma were studied . from their comparative biochemical analysis , authors came to the conclusion that prf consists of an intrinsic assembly of cytokines , glycemic chains , and structural glycoproteins enmeshed in a slowly polymerized fibrin network having synergistic effects on healing processes . therefore , prf can be considered as not only a new generation of platelet gel but a completely usable healing concentrate gel . they also evaluated the quantity of five significant cell mediators within prp supernatant and prf clot exudates , three proinflammatory cytokines ( il - 1 , il - 6 , tnf - ) , and anti - inflammatory cytokine ( il - 4 ) , vascular endothelial growth factor ( vegf ) by collecting blood from fifteen 20 - 28 year old healthy non - smoker males and stated that the cytokine concentrations were high in prf clot exudates than in plasma and serum samples with the exception that the concentration of vegf is significantly high in serum samples . only a perfect understanding of its components and their significance will enable us to comprehend the clinical results obtained and subsequently extend the fields of therapeutic application of this protocol . this controlled , randomized , split mouth design for the treatment of bilateral isolated miller 's class i and ii gingival recessions indicated that caf surgery alone or in combination with prf are effective procedures to cover denuded roots . the data obtained from a combination of caf - prf after a period of 6 months showed additional benefits along with mean root coverage in the treatment of miller 's class i and ii gingival recessions when compared with the caf technique alone .\noutput:\n" }, { "from": "agent", "value": "background : there are various techniques developed to treat the exposed roots , a recent innovation in dentistry is the use of second generation platelet concentrate which is an autologous platelet - rich fibrin gel ( prf ) with growth factors and cicatricial properties for root coverage procedures . therefore , the present research was undertaken to study the additional benefits of prf when used along with coronally advanced flap ( caf ) . materials and methods : total of 15 systemically healthy subjects presenting bilateral isolated miller 's class i and ii recession were enrolled into the study . each patient was randomly treated with a combination of caf along with a platelet - rich fibrin ( prf ) membrane on the test site and caf alone on the control site . recession depth , clinical attachment level ( cal ) , and width of keratinized gingiva ( wkg ) were compared with baseline at 1 , 3 , and 6 months between test and control sites.results : mean percentage root coverage in the test group after 1 , 3 , and 6 months was 34.58 , 70.73 , and 100 , respectively . differences between the control and test groups were statistically significant . this study also showed a statistically significant increase in wkg in the test group ( 2.94 0.77 at baseline to 5.38 1.67 at 6 months ) . conclusion : caf is a predictable treatment for isolated miller 's class i and ii recession defects . the addition of prf membrane with caf provides superior root coverage with additional benefits of gain in cal and wkg at 6 months postoperatively ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the first direct detection of gravitational waves ( gws ) , widely expected in the mid 2010s with advanced ground - based interferometers , will represent the culmination of a fifty - year experimental quest . soon thereafter , newly plentiful gw observations will begin to shed light on the structure , populations , and astrophysics of mostly dark , highly relativistic objects such as black holes and neutron stars . in the low - frequency band that will be targeted by space - based detectors ( roughly 10 to 1 hz ) , gw observations will provide a census of the massive black - hole binaries at the center of galaxies , and characterize their merger histories ; probe the galactic population of binaries that include highly evolved , degenerate stars ; study the stellar - mass objects that spiral into the central black holes in galactic nuclei ; and possibly detect stochastic gw backgrounds from the dynamical evolution of the very early universe . thus , there are very strong astrophysical motivations to observe the universe in gws , especially because the systems and phenomena that can be observed in this fashion are largely orthogonal to those accessible to traditional electromagnetic ( em ) and astroparticle astronomy . einstein s theory of gravity , general relativity ( gr ) , has been confirmed by extensive experimental tests ; but these have largely been confined to the solar system , where gravity is well approximated by newtonian gravity with small corrections . a few tests , based on observations of binary compact - object systems , have confirmed the weakest ( leading - order ) effects of gw generation . by contrast , observation of strong gws will provide the first direct observational probe of the dynamical , strong - field regime of gr , where the nature and behavior of gravity can be significantly different from the newtonian picture . gws are prima facie the perfect probe to investigate gravitation , since they originate directly from the bulk motion of gravitating matter , relieving the need to understand and model the physics of other intermediate messengers , typically photons from stellar surfaces or black - hole surroundings . already today we can rely on a very sophisticated understanding of the analytical and numerical techniques required to model gw sources and their gw emission , including the post - newtonian expansion , black - hole perturbation theory , numerical relativity for vacuum spacetimes , spacetimes with gases or magnetized plasmas , and much more . that these techniques should have been developed so much in the absence of a dialogue with experimental data ( except for the binary pulsar ) is witness to the great perceived promise of gw astronomy . for a birds - eye view of the field , see the living review by sathyaprakash and schutz , who cover the physics of gws , the principles of operation of gw detectors , the nature of gw sources , the data analysis of gw signals , and the science payoffs of gw observations for physics , astrophysics , and cosmology . this review focuses on the opportunities to challenge or confirm our understanding of gravitational physics that will be offered by forthcoming space - based missions to observe gws in the low - frequency band between 10 and 1 hz . most of the literature on this subject has focused on one mission design , lisa ( the laser interferometer space antenna ) , which was studied jointly by nasa and esa between 2001 and 2011 . in 2011 , budgetary and programmatic reasons led the two space agencies to end this partnership , and to pursue space - based gw detection separately , studying cheaper , rescoped lisa - like missions . esa s proposed elisa / ngo would be smaller than lisa , fly on orbits closer to earth , and operate interferometric links only along two arms . in 2012elisa was considered for implementation as esa s first large mission ( l1 ) in the cosmic vision program . a planetary mission was selected instead , but elisa will be in the running for the next launch slot ( l2 ) , with a decision coming as soon as 2014 . nasa ran studies on a broader range of missions , including several variants of lisa to be implemented by nasa alone , as well as options with a geocentric orbit ( omega ) , and without drag - free control ( lagrange ) . the final study report concludes that scientifically compelling missions can be carried out for less , but not substantially less , than the full lisa cost ; that scientific performance decreases far more rapidly than cost ; and that no design choice or technology can make a dramatic reduction in cost without much greater risks . the nasa study noted the possibility of participation in the esa - led elisa mission ( if selected by esa ) as a minority partner . whatever specific design is eventually selected , it is likely that its architecture , technology , and scientific reach will bear a strong resemblance to lisa s ( with the appropriate scalings in sensitivity , mission duration , and so on ) . thus , the research reviewed in this article , which was targeted in large part to lisa , is still broadly relevant to future missions . such lisa - like observatories are characterized by a few common elements : a set of three spacecraft in long - baseline ( mkm ) orbits , monitoring their relative displacements using laser interferometry ; drag - free operation ( except for lagrange ) , whereby displacement measurements are referenced to freely falling test masses protected by the spacecraft , which hover around the masses using precise micro - newton thrusters ; frequency correction of laser noise using a variety of means , including onboard cavities and interferometers , arm locking , and a lisa - specific technique known as time - delay interferometry . the predictions of gr that can be tested by space - based gw observatories include the absence of gravitational fields other than the metric tensor ; the number and character of gw polarization states ; the speed of gw propagation ; the detailed progress of binary inspiral , as driven by nonlinear gravitational dynamics and loss of energy to gws ; the strength and shape of the gws from binary merger and ringdown ; the true nature of astrophysical black holes ; and more . some of these tests will also be performed with ground - based gw detectors and pulsar - timing observations , but space - based tests will almost always have superior accuracy and significance , because low - frequency sources are intrinsically stronger , and will spend a larger time within the band of good detector sensitivity . for binary systems with very asymmetric mass ratios , such as extreme mass - ratio inspirals ( emris ) , lisa - like missions will measure hundreds of thousands of orbital cycles ; because successful detections require matching the phase of signals throughout their evolution , it follows that these observations will be exquisitely sensitive to source parameters . the data - analysis detection problem will be correspondingly delicate , but has been tackled both theoretically , and in a practical program of mock data challenges for lisa . section 2 provides the briefest overview of einstein s gr , of the theoretical framework in which it can be tested , and of a few leading alternative theories . it also introduces the black - hole paradigm , which augments einstein s equations with a few assumptions of physicality that lead to the prediction that the end result of gravitational collapse are black holes described by the kerr metric . section 4 summarizes the main classes of gw sources that would be observed by lisa - like detectors , and that can be used to test gr . section 5 examines the tests of gravitational dynamics that can be performed with these sources , while section 6 discusses the tests of the black - hole nature and structure . ( a conspicuous omission are possible stochastic gw backgrounds of cosmological origin ; indeed , in this article we do not discuss the role of space - based detectors as probes of cosmology and early - universe physics . ) newton s theory of gravitation provided a description of the effect of gravity through the inverse square law without attempting to explain the origin of gravity . the inverse square law provided an accurate description of all measured phenomena in the solar system for more than two hundred years , but the first hints that it was not the correct description of gravitation began to appear in the late 19th century , as a result of the improved precision in measuring phenomena such as the perihelion precession of mercury . einstein s contribution to our understanding of gravity was not only practical but also aesthetic , providing a beautiful explanation of gravity as the curvature of spacetime . in developing gr as a generally covariant theory based on a dynamical spacetime metric , einstein sought to extend the principle of relativity to gravitating systems , and he built on the crucial 1907 insight that the equality of inertial and gravitational mass allowed the identification of inertial systems in homogeneous gravitational fields with uniformly accelerated frames the principle of equivalence . einstein was also guided by his appreciation of ricci and levi - civita s absolute differential calculus ( later to become differential geometry ) , arguably as much as by the requirement to reproduce newtonian gravity in the weak - field limit . indeed , one could say that gr was born of almost pure thought . einstein s theory of gr is described by the action 1 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { s _ { { \\ rm { gr } } } } = \\ int { \\ sqrt { - g } r { { \\ rm { d } } ^ 4 } x } , $ $ \\ end { document } in which g is the determinant of the spacetime metric and r = gr is the ricci scalar , where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { r ^ { \\ mu \\ nu } } = r _ { \\ mu \\ alpha \\ nu } ^ \\ alpha $ \\ end { document } is the ricci tensor , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ r _ { \\ beta \\ gamma \\ delta } ^ \\ alpha = \\ gamma _ { \\ beta \\ delta , \\ gamma } ^ \\ alpha - \\ gamma _ { \\ beta \\ gamma , \\ delta } ^ \\ alpha + \\ gamma _ { \\ gamma \\ lambda } ^ \\ alpha \\ gamma _ { \\ beta \\ delta } ^ \\ lambda - \\ gamma _ { \\ delta \\ lambda } ^ \\ alpha \\ gamma _ { \\ beta \\ gamma } ^ \\ lambda $ \\ end { document } the riemann curvature tensor , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ gamma _ { \\ beta \\ gamma } ^ \\ alpha = { g ^ { \\ alpha \\ delta } } ( { g _ { \\ beta \\ delta , \\ gamma } } + { g _ { \\ delta \\ gamma , \\ beta } } - { g _ { \\ beta \\ gamma , \\ delta } } ) $ \\ end { document } the affine connection , and a comma denotes a partial derivative . when coupled to a matter distribution , this action yields the field equations 2 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { g _ { \\ mu \\ nu } } \\ equiv { r _ { \\ mu \\ nu } } - { 1 \\ over 2 } { g _ { \\ mu \\ nu } } r = { { 8 \\ pi g } \\ over { { c ^ 4 } } } { t _ { \\ mu \\ nu } } , $ $ \\ end { document } where denotes the stress - energy tensor of the matter . since the development of the theory , gr has withstood countless experimental tests based on measurements as different as atomic - clock precision , orbital dynamics ( most notably lunar laser ranging ) , astrometry , and relativistic astrophysics ( most exquisitely the binary pulsar , but not only ) . it is therefore the correct and natural benchmark against which to compare alternative theories using future observations and we will follow the same approach in this article . unlike in the case of newtonian gravity at the time that gr was developed , there are no current observations that gr can not explain that can be used to guide development of alternatives .1 nonetheless , there are crucial aspects of einstein s theory that have never been probed directly , such as its strong - field dynamics and the propagation of field perturbations ( gws ) . furthermore , it is known that classical gr must ultimately fail at the planck scale , where quantum effects become important , and traces of the quantum nature of gravity may be accessible at lower energies . as emphasized by will , gr has no adjustable constants , so every test is potentially deadly , and a probe that could reveal new physics . will s living review and his older monograph are the fundamental references about the experimental verification of gr . in this section , we give only a brief overview of what may be called will s standard model for alternative theories of gravity , which proceeds through four steps : a ) strong evidence for the equivalence principle supports a metric formulation for gravity ; b ) metric theories are classified according to what gravitational fields ( scalar , vector , tensor ) they prescribe ; c ) slow - motion , weak - field conservative dynamics are described in a unified parameterized post - newtonian ( ppn ) formalism , and constrained by experiment and observations ; d ) finally , equations for the slow - motion generation and weak - field propagation of gravitational radiation are derived separately for each metric theory , and again compared to observations . many of the tests of gravitational physics envisaged for lisa belong in this last sector of will s standard model , and are discussed in section 5.1 of this review . this scheme however leaves out two other important points of contact between gravitational phenomenology and lisa s gw observations : the strong - field , nonlinear dynamics of black holes and their structure and excitations , especially as probed by small orbiting bodies . we will deal with these in sections 5 and 6 , respectively ; but let us first delve into will s standard model . the equivalence principle and metric theories of gravitation . einstein s original intuition placed the equivalence principle as a cornerstone for the theories that describe gravity as curved spacetime . as formulated by newton , the principle states simply that inertial and gravitational mass are proportional , and therefore all test bodies fall with the same acceleration ( in modern usage , this is known as the weak equivalence principle , or wep ) . dicke later recognized that in developing gr einstein had implicitly posited a broader principle ( einstein s equivalence principle , or eep ) that consists of wep plus local lorentz invariance and local position invariance : that is , of the postulates that the outcome of local non - gravitational experiments is independent of , respectively , the velocity and position of the local freely - falling reference frames in which the experiments are performed . weak equivalence principle ( wep ) : gravitational and inertial masses are equivalent ( neglecting self gravity ) .2 . einstein equivalence principle ( eep ) : local position invariance and local lorentz invariance apply in addition to the wep .3 . strong equivalence principle ( sep ) : eep applies also for self - gravitating objects . turyshev gives a current review of the experimental verification of wep ( shown to hold to parts in 10 by differential free - fall tests ) , local lorentz invariance ( verified to parts in 10 by clock - anisotropy experiments ) , and local position invariance ( verified to parts in 10 by gravitational - redshift experiments , and to much greater precision when looking for possible time variations of fundamental constants ) . although these three parts of eep appear distinct in their experimental consequences , their underlying physics is necessarily related in any theory of gravity , so schiff conjectured ( and others argued convincingly ) that any complete and self - consistent theory of gravity that embodies wep must also realize eep . eep leads to metric theories of gravity in which spacetime is represented as a pseudo - riemannian manifold , freely - falling test bodies move along the geodesics of its metric , and non - gravitational physics is obtained by applying special - relativistic laws in local freely - falling frames . gr is , of course , a metric theory of gravity ; so are scalar - vector - tensor theories such as brans - dicke theory , which include other gravitational fields in addition to the metric . by contrast , theories with dynamically varying fundamental constants and theories ( such as superstring theory ) that introduce additional wep - violating gravitational fields [ 471 , section 2.3 ] are not metric . neither are most theories that provide short - range and long - range modifications to newton s inverse - square law . the scalar and vector fields in scalar - vector - tensor theories can not directly affect the motion of matter and other non - gravitational fields ( which would violate wep ) , but they can intervene in the generation of gravity and modify its dynamics . these extra fields can be dynamical ( i.e. , determined only in the context of solving for the evolution of everything else ) or absolute ( i.e. , assigned a priori to fixed values ) . the minkowski metric of special relativity is the classic example of absolute field ; such fields may be regarded as philosophically unpleasant by those who dislike feigning hypotheses , but they have a right of citizenship in modern physics as frozen inthe additional fields can potentially alter the outcome of local gravitational experiments : while the local gravitational effects of different metrics far away can always be erased by describing physics in a freely - falling reference frame ( which is to say , the local boundary conditions for the metric can be arranged to be flat spacetime ) , the same is not true for scalar and vector fields , which can then affect local gravitational dynamics by their interaction with the metric . this amounts to a violation not of eep , but of the strong equivalence principle ( sep ) , which states that eep is also valid for self - gravitating bodies and gravitational experiments . sep is verified to parts in 10 by combined lunar laser - ranging and laboratory experiments . so far , gr appears to be the only viable metric theory that fully realizes sep . the ppn formalism . because the experimental consequences of different metric theories follow from the specific metric that is generated by matter ( possibly with the help of the extra gravitational fields ) , and because all these theories must realize newtonian dynamics in appropriate limiting conditions , it is possible to parameterize them in terms of the coefficients of a slow - motion , weak - field expansion of the metric . these coefficients appear in front of gravitational potentials similar to the newtonian potential , but involving also matter velocity , internal energy , and pressure . this scheme is the parameterized post - newtonian formalism , pioneered by nordtvedt and extended by will ( see for details ) . of the ten ppn parameters in the current version of the formalism , two are the celebrated and ( already introduced by eddington , robertson , and schiff for the classical tests of gr ) that rule , respectively , the amount of space curvature produced by unit rest mass and the nonlinearity in the superposition of gravitational fields . in gr , and each have the value 1 . the other eight parameters , if not zero , give origin to violations of position invariance ( ) , lorentz invariance ( 13 ) , or even of the conservation of total momentum ( 3 , 14 ) and total angular momentum ( 13 , 14 ) . the ppn formalism is sufficiently accurate to describe the tests of gravitation performed in the solar system , as well as many tests using binary - pulsar observations . the parameter is currently constrained to 1 a few 10 by tests of light delay around massive bodies using the cassini spacecraft ; to 1 a few 10 by lunar laser ranging .2 the other ppn parameters have comparable bounds around zero from solar - system and pulsar measurements , except for 3 , which is known exceedingly well from pulsar observations . tests in the ppn framework have tightly constrained the field of viable alternatives to gr , largely excluding theories with absolute elements that give rise to preferred - frame effects . the ( indirect ) observation of gw emission from the binary pulsar and the accurate prediction of its by einstein s quadrupole formula have definitively excluded other theories . yetmore gr alternatives were conceived to illuminate points of principle , but they are not well motivated physically and therefore are hardly candidates for experimental verification . some of the theories that are still alive are described in the following . the addition of a single scalar field to gr produces a theory described by the einstein - frame action ( see , e.g. , ) , 3 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ tilde i = { ( 16 \\ pi g ) ^ { - 1 } } \\ int { [ \\ tilde r - 2 { { \\ tilde g } ^ { \\ mu \\ nu } } { \\ partial _ \\ mu } \\ varphi { \\ partial _ \\ nu } \\ varphi - v ( \\ varphi ) ] { { ( - \\ tilde g ) } ^ { 1/2 } } { { \\ rm { d } } ^ 4 } x + { i _ { { \\ rm { matter } } } } ( { \\ psi _ { \\ rm { m } } } , { a ^ 2 } ( \\ varphi ) { { \\ tilde g } _ { \\ mu \\ nu } } ) } , $ $ \\ end { document } where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ tilde g } _ { \\ mu \\ nu } } $ \\ end { document } is the metric , the ricci curvature scalar \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ tilde r } $ \\ end { document } yields the general - relativistic einstein - hilbert action , and the two adjacent terms are kinetic and potential energies for the scalar field . note that in the action imatter for matter dynamics , the metric couples to matter through the function a ( ) , so this representation is not manifestly metric ; it can however be made so by a change of variables that yields the jordan - frame action , 4 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ i = { ( 16 \\ pi g ) ^ { - 1 } } \\ int { [ \\ phi r - { \\ phi ^ { - 1 } } \\ omega ( \\ phi ) { g ^ { \\ mu \\ nu } } { \\ partial _ \\ mu } \\ phi { \\ partial _ \\ nu } \\ phi - { \\ phi ^ 2 } v ] { { ( - g ) } ^ { 1/2 } } { { \\ rm { d } } ^ 4 } x + { i _ { { \\ rm { matter } } } } ( { \\ psi _ { \\ rm { m } } } , { g _ { \\ mu \\ nu } } ) } , $ $ \\ end { document } where a ( ) is the transformed scalar field , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { g _ { \\ mu \\ nu } } \\ equiv { a ^ 2 } ( \\ varphi ) { { \\ tilde g } _ { \\ mu \\ nu } } $ \\ end { document } is the physical metric underlying gravitational observations , and 3 + 2 ( ) = [ d ( ln a ( ) ) / d ] . brans - dicke theory corresponds to fixing to a constant bd , and it is indistinguishable from gr in the limit bd . in the ppn framework , the only parameter that differs from gr is = ( 1 + bd ) / ( 2 + bd ) . damour and esposito - farese considered an expansion of log a ( ) around a cosmological background value , 5 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ log a ( \\ varphi ) = { \\ alpha _ 0 } ( \\ varphi - { \\ varphi _ 0 } ) + { 1 \\ over 2 } { \\ beta _ 0 } { ( \\ varphi - { \\ varphi _ 0 } ) ^ 2 } + \\ cdots , $ $ \\ end { document } where 0 ( and further coefficients ) = 0 reproduces brans - dicke with \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ alpha _ 0 ^ 2 = 1 / ( 2 { \\ omega _ { { \\ rm { bd } } } } + 3 ) , \\ , { \\ beta _ 0 } 0 $ \\ end { document } , 00 causes the evolution of the scalar field toward 0 ( and therefore toward gr ) ; and 00 may allow a phase change inside objects like neutron stars , leading to large sep violations . these parameters are bound by solar - system , binary - pulsar , and gw observations . scalar - tensor theories have found motivation in string theory and cosmological models , and have attracted the most attention in terms of tests with gw observations . the most general second - order action in such a theory takes the form 6 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { s = { 1 \\ over { 16 \\ pi g } } \\ int { { { \\ rm { d } } ^ 4 } x \\ sqrt { - g } } \\ left [ { ( 1 + \\ omega { u _ \\ mu } { u ^ \\ nu } ) r - k _ { \\ alpha \\ beta } ^ { \\ mu \\ nu } u _ { ; \\ mu } ^ \\ alpha u _ { ; \\ nu } ^ \\ beta + \\ lambda ( { u _ \\ mu } { u ^ \\ mu } + 1 ) } \\ right ] } , \\ \\ { { \\ rm { where } } \\ , \\ , k _ { \\ alpha \\ beta } ^ { \\ mu \\ nu } = { c_1 } { g ^ { \\ mu \\ nu } } { g _ { \\ alpha \\ beta } } + { c_2 } \\ delta _ \\ alpha ^ \\ mu \\ delta __ \\ beta ^ \\ mu \\ delta _ \\ alpha ^ \\ nu - { c_4 } { u ^ \\ mu } { u ^ \\ nu } { g _ { \\ alpha \\ beta } } , \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ \\ end { array } $ $ \\ end { document } in which a semicolon denotes covariant differentiation , and the coefficients ci are arbitrary constants . there are two types of vector - tensor theories : in unconstrained theories , 0 and the constant is arbitrary , while in einstein - aether theories the vector field is constrained to have unit norm , so the lagrange multiplier is arbitrary and the constraint allows to be absorbed into a rescaling of g. for the unconstrained theory , only versions of the theory with c4 = 0 have been studied and for these the field equations are 7 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { \\ quad \\ quad \\ quad \\ quad { r _ { \\ kappa \\ lambda } } - { 1 \\ over 2 } r { g _ { \\ kappa \\ lambda } } + \\ omega \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ omega ) } + \\ eta \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ eta ) } + \\ epsilon \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ epsilon ) } + \\ tau \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ tau ) } + \\ lambda { g _ { \\ kappa \\ lambda } } = 0 , } \\ \\ { \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ epsilon f _ { \\ mu \\ nu } ^ { ; \\ nu } + { 1 \\ over 2 } \\ tau u _ { \\ mu ; \\ nu } ^ { ; \\ nu } - { 1 \\ over 2 } \\ omega { u _ \\ mu } r - { 1 \\ over 2 } \\ eta { u ^ \\ alpha } { r _ { \\ mu \\ alpha } } = 0 , } \\ \\ { \\ quad \\ quad \\ quad \\ quad \\ quad \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ omega ) } = { u _ \\ kappa } { u _ \\ lambda } r + { u ^ 2 } { r _ { \\ kappa \\ lambda } } - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { u ^ 2 } r - { { ( { u ^ 2 } ) } _ { ; \\ kappa \\ lambda } } + { g _ { \\ kappa \\ lambda } } { \\ square_g } { u ^ 2 } , } \\ \\ { \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ eta ) } = 2 { u ^ \\ alpha } { u _ { \\ left [ \\ kappa \\ right . } } { r _ { \\ left . \\ lambda \\ right ] } } _ \\ alpha - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { u ^ \\ alpha } { u ^ \\ beta } { r _ { \\ alpha \\ beta } } - { { ( { u ^ \\ alpha } { u _ { \\ left [ \\ kappa \\ right . } } ) } { } _ { \\ left . { ; \\ lambda } \\ right ] \\ alpha } } + { 1 \\ over 2 } { \\ square_g } ( { u _ \\ kappa } { u _ \\ lambda } ) + { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { { ( { u ^ \\ alpha } { u ^ \\ beta } ) } _ { ; \\ alpha \\ beta } } , \\ quad \\ quad \\ quad \\ quad \\ , \\ , } \\ \\ { \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ , \\ , \\ , \\ , \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ epsilon ) } = - 2 ( f _ \\ kappa ^ \\ alpha { f _ { \\ lambda \\ alpha } } - { 1 \\ over 4 } { g _ { \\ kappa \\ lambda } } { f _ { \\ alpha \\ beta } } { f ^ { \\ alpha \\ beta } } ) , } \\ \\ { \\ theta _ { \\ kappa \\ lambda } ^ { ( \\ tau ) } = { u _ { \\ kappa ; \\ alpha } } u _ \\ lambda ^ { ; \\ alpha } + { u _ { \\ alpha ; \\ kappa } } u _ { ; \\ lambda } ^ \\ alpha - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { u _ { \\ alpha ; \\ beta } } { u ^ { \\ alpha ; \\ beta } } + { { ( { u ^ \\ alpha } { u _ { \\ left [ { \\ kappa ; \\ lambda } \\ right ] } } - u _ { ; \\ left [ \\ kappa \\ right . } ^ \\ alpha { u _ { \\ left . \\ lambda \\ right ] } } - { u _ { \\ left [ \\ kappa \\ right . } } u _ { \\ left . \\ lambda \\ right ] } ^ { ; \\ alpha } ) } _ { ; \\ alpha } } , } \\ \\ \\ end { array } $ $ \\ end { document } where f = u ; u ; , u uu , = c2 , = ( c2 + c3 ) / 2 , and = ( c1 + c2 + c3 ) . we use the usual subscript notation , such that ( , ) and denote symmetric and antisymmetric sums . in the constrained einstein - aether theorythe field equations are 8 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { j ^ \\ alpha } _ { \\ mu ; \\ alpha } - { c_4 } { { \\ dot u } ^ \\ alpha } u _ { ; \\ mu } ^ \\ alpha = \\ lambda { u _ \\ mu } , \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ , \\ , \\ , } \\ \\ { { \\ rm { where } } \\ , { j ^ \\ alpha } _ \\ mu = k _ { \\ mu \\ nu } ^ { \\ alpha \\ beta } u _ { ; \\ beta } ^ \\ nu , \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { { g _ { \\ alpha \\ beta } } = t _ { \\ alpha \\ beta } ^ { ( u ) } + { { 8 \\ pi g } \\ over { { c ^ 4 } } } t _ { \\ alpha \\ beta } ^ { { \\ rm { matter } } } , \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { t _ { \\ alpha \\ beta } ^ { ( u ) } \\ equiv { { \\ left ( { { j _ { \\ left ( \\ alpha \\ right . } } ^ \\ mu { u _ { \\ left . \\ beta \\ right ) } } - { j _ { \\ left ( { \\ alpha \\ beta } \\ right ) } } { u ^ \\ mu } } \\ right ) } _ { ; \\ mu } } + { c_1 } \\ left ( { u _ { ; \\ mu } ^ \\ alpha u _ \\ beta ^ { ; \\ mu } - { u _ { \\ mu ; \\ alpha } } u _ { ; \\ beta } ^ \\ mu } { \\ quad \\ quad \\ quad + \\ left [ { { u _ \\ nu } j _ { ; \\ mu } ^ { \\ mu \\ nu } - { c_4 } { { \\ dot u } ^ 2 } } \\ right ] { u _ \\ alpha } { u _ \\ beta } - { 1 \\ over 2 } { g _ { \\ alpha \\ beta } } { l_u } , } \\ \\ \\ end { array } $ $ \\ end { document } where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ dot u ^ \\ alpha } \\ equiv { u ^ \\ beta } u _ { ; \\ beta } ^ \\ alpha , \\ , { l_u } = - k _ { \\ mu \\ nu } ^ { \\ alpha \\ beta } \\ , u _ { ; \\ alpha } ^ \\ nu u _ { ; \\ beta } ^ \\ nu $ \\ end { document } is the aether lagrangian , and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ t _ { \\ alpha \\ beta } ^ { { \\ rm { matter } } } $ \\ end { document } is the usual matter stress - energy tensor . via field redefinitionthis theory can be shown to be equivalent to gr if c1 + c4 = 0 , c1 + c2 + c3 = 0 , and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { c_3 } = \\ pm \\ sqrt { { c_1 } ( { c_1 } - 2 ) } $ \\ end { document } . field redefinition can also be used to set c1 + c3 = 0 ; if this constraint is imposed then equivalence to gr is only achieved if the ci are all zero . this constraint is therefore appropriate to pose einstein - aether theory as an alternative to test against gr , since then any non - zero values of the ci would represent genuine deviations from gr . unconstrained vector - tensor theories were introduced in the 1970s as a straw - man alternative to gr , but they have four arbitrary parameters and leave the magnitude of the vector field unconstrained , which is a serious defect . interest in einstein - aether theories was prompted by the desire to construct a covariant theory that violated lorentz invariance under boosts , by having a preferred reference frame the aether , represented by the vector u. the preferred reference frame also provides a universal notion of time . interest in theories that violate lorentz symmetry has recently been revived as a possible window onto aspects of quantum gravity . the natural extension of scalar - tensor and vector - tensor theories are scalar - vector - tensor theories in which the gravitational field is coupled to a vector field and one or more scalar fields . these theories are relativistic generalizations of modified newtonian dynamics ( mond ) , which was proposed in order to reproduce observed rotation curves on galactic scales . the action takes the form 9 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ s = { 1 \\ over { 16 \\ pi } } \\ int { { { \\ rm { d } } ^ 4 } x } \\ sqrt { - g } ( { l_g } + { l_s } + { l_u } + { l _ { { \\ rm { matter } } } } ) , $ $ \\ end { document } where lg = ( r 2 ) / g and lmatter are the usual gravitational and matter lagrangians . there are two main versions of the theory , which differ in the choice of the scalar - field and vector - field lagrangians ls and lu . in tensor - vector - scalar gravity ( teves ) the dynamical vector field u is coupled to a dynamical scalar field . a second scalar field is here considered non - dynamical . the lagrangians are 10 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { l_s } = { 1 \\ over { 2g } } \\ left [ { { \\ sigma ^ 2 } \\ left ( { { g ^ { \\ alpha \\ beta } } - { u ^ \\ alpha } { u ^ \\ beta } } \\ right ) { \\ phi _ { , \\ alpha } } { \\ phi _ { , \\ beta } } + { 1 \\ over 2 } { g \\ over { { l ^ 2 } } } { \\ sigma ^ 4 } f ( g { \\ sigma ^ 2 } ) } \\ right ] , } \\ \\ { { l_u } = { k \\ over { 2g } } \\ left [ { { g ^ { \\ alpha \\ beta } } { g ^ { \\ mu \\ nu } } { b _ { \\ alpha \\ mu } } { b _ { \\ beta \\ nu } } + 2 { \\ lambda \\ over k } ( { u ^ \\ mu } { u _ \\ mu } + 1 ) } \\ right ] , \\ quad \\ quad \\ quad \\ , \\ , } \\ \\ \\ end { array } $ $ \\ end { document } where b = u , u , , f is an unspecified dimensionless function , k is a dimensionless parameter , and l is a constant length parameter . the lagrange multiplier is spacetime dependent , set to enforce normalization of the vector field uu = 1 . in tevesthe physical metric that governs the gravitational dynamics of ordinary matter does not coincide with g , but is determined by the scalar field through 11 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ hat g _ { \\ mu \\ nu } } = { e ^ { 2 \\ phi } } { g _ { \\ mu \\ nu } } - 2 { u _ \\ mu } { u _ \\ nu } \\ sinh ( 2 \\ phi ) { . } $ $ \\ end { document } an alternative version of teves , called bi - scalar - tensor - vector gravity ( bstv ) has also been proposed , in which the scalar field is allowed to be dynamical . teves is able to explain galaxy rotation curves and satisfies constraints from cosmology and gravitational lensing , but stars are very unstable and the bullet cluster observations ( which point to dark matter ) can not be explained . in scalar - tensor - vector gravity ( stvg ) the lagrangian for the vector field is taken to be 12 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l_u } = \\ omega \\ left [ { { b ^ { \\ mu \\ nu } } { b _ { \\ mu \\ nu } } - 2 { \\ mu ^ 2 } { u ^ \\ mu } { u _ \\ mu } + { v_u } ( u ) } \\ right ] , $ $ \\ end { document } with b defined as before . the three constants , , and g that enter this action and the gravitational action are then taken to be scalar fields governed by the lagrangian 13 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l_s } = { { 16 \\ pi } \\ over g } \\ left [ { { 1 \\ over 2 } { g ^ { \\ nu \\ rho } } \\ left ( { { { { g _ { , \\ nu } } { g _ { , \\ rho } } } \\ over { { g ^ 2 } } } + { { { \\ mu _ { , \\ nu } } { \\ mu _ { , \\ rho } } } \\ over { { \\ mu ^ 2 } } } - { \\ omega _ { , \\ nu } } { \\ omega _ { , \\ rho } } } \\ right ) + { { { v_g } ( g ) } \\ over { { g ^ 2 } } } + { { { v _ \\ mu } ( \\ mu ) } \\ over { { \\ mu ^ 2 } } } + { v _ \\ omega } ( \\ omega ) } \\ right ] { . } $ $ \\ end { document } it is claimed that stvg predicts no deviations from gr on the scale of the solar system or for small globular clusters , and that it can reproduce galactic rotation curves , gravitational lensing in the bullet cluster , and a range of cosmological observations . it has been proposed that an extension of the esa - led lisa pathfinder technology - demonstration mission may allow additional constraints on this class of theories . to datethis theory is derived by replacing r with an arbitrary function f ( r ) in the einstein - hilbert action . the action is extremized with respect to the metric coefficients only , and the connection is taken to be the metric connection , depending on the metric components in the standard way . the resulting field equations are 14 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ ( - { r _ { ; \\ kappa } } { r _ { ; \\ lambda } } + { g _ { \\ kappa \\ lambda } } { r _ { ; \\ mu } } { r ^ { ; \\ mu } } ) f ^ { \\ prime \\ prime \\ prime } ( r ) + ( - { r _ { ; \\ kappa \\ lambda } } + { g _ { \\ kappa \\ lambda } } { \\ square } r ) f ^ { \\ prime \\ prime } ( r ) + { r _ { \\ kappa \\ lambda } } f ^ { \\ prime } ( r ) - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } f ( r ) = 0 { . } $ $ \\ end { document } in the palatini formalism , the field equations are found by extremizing the action over both the metric and the connection . for an f ( r ) action the resulting equations are 15 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { r _ { \\ kappa \\ lambda } } { f ^ \\ prime } ( r ) - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } f ( r ) = 0 , } & { { \\ nabla _ \\ alpha } \\ left [ { \\ sqrt { - g } { f ^ \\ prime } ( r ) { g ^ { \\ kappa \\ lambda } } } \\ right ] = 0 { . } } \\ \\ \\ end { array } $ $ \\ end { document } if the second derivative f ( r ) 0 , metric f ( r ) gravity can be shown to be equivalent to a brans - dicke theory with bd = 0 , while palatini f ( r ) gravity is equivalent to a brans - dicke theory with bd = 3/2 , with no constraint imposed on f ( r ) . in both cases , f ( r ) theories have attracted a lot of interest in a cosmological context , since the flexibility in choosing the function f ( r ) allows a wide range of cosmological phenomena to be described , including inflation and late - time acceleration , without violating constraints from big - bang nucleosynthesis . however , metric f ( r ) theories are strongly constrained by solar - system and laboratory measurements if the scalar degree of freedom is assumed to be long - ranged , which modifies the form of the gravitational potential . this problem can be avoided by assuming a short - range scalar field , but then f ( r ) theories can only explain the early expansion of the universe and not late - time acceleration . the chameleon mechanism has been invoked to circumvent this , as it allows the scalar - field mass to be a function of curvature , so that the field can be short ranged within the solar system but long ranged on cosmological scales . for example , in palatini f ( r ) gravity the post - newtonian metric depends on the local matter density , while in metric f ( r ) gravity with f ( r ) 0 there is a ricci - scalar instability that arises because the effective gravitational constant increases with increasing curvature , leading to a runaway instability for small stars . we refer the reader to for more complete reviews of the current understanding of f ( r ) gravity . yunes and others have recently developed an extensive analysis of the observational consequences of jackiw and pi s chern - simons gravity , which extends the hilbert action with an additional pontryagin term * rr that is quadratic in the riemann tensor : 16 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ i = { ( 16 \\ pi g ) ^ { - 1 } } \\ int { [ \\ tilde r - { 1 \\ over 4 } \\ theta ^ { \\ ast } rr ] { { ( - g ) } ^ { 1/2 } } { { \\ rm { d } } ^ 4 } x + { { { \\ rm i } } _ { { \\ rm { matter } } } } ( { \\ psi _ { \\ rm { m } } } , { g _ { \\ mu \\ nu } } ) ; } $ $ \\ end { document } here \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { } ^ * rr = { } ^ * { r ^ a } _ b { } ^ { cd } { r ^ b } _ { acd } $ \\ end { document } is built with the help of the dual riemann tensor \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ ^ { \\ ast } { r ^ a } _ b { } ^ { cd } = { 1 \\ over 2 } { \\ epsilon ^ { cde \\ , f } } { r ^ a } _ { be \\ , f } $ \\ end { document } , and it can be expressed as the divergence of the gravitational chern - simons topological current ; 3 the scalar field can be treated either as a dynamical quantity , or an absolute field . in both cases , * rr vanishes , either dynamically , or as a constraint on acceptable solutions , needed to enforce coordinate - invariant matter dynamics , which restricts the space of solutions available to gr . chern - simons gravity is motivated by string theory and by the attempt to develop a quantum theory of gravity satisfying a gauge principle . the pontryagin term arises in the standard model of particle physics as a gauge anomaly : the classical gravitational noether current that comes from the symmetry of the gravitational action is no longer conserved when the theory is quantized , but has a divergence proportional to the pontryagin term . this anomaly can be canceled by modifying the action via the addition of the chern - simons pontryagin term . the same type of correction arises naturally in string theory through the green - schwarz anomaly - canceling mechanism , and in loop quantum gravity to enforce parity and charge - parity conservation . the presence of the chern - simons correction leads to parity violation , which has various observable consequences , with magnitude depending on the chern - simons coupling , which string theory predicts will be at the planck scale . if so , these effects will never be observable , but various mechanisms have been proposed that could enhance the strength of the chern - simons coupling , such as non - perturbative instanton corrections , fermion interactions , large intrinsic curvatures or small string couplings at late times . for further details on all aspects of chern - simons gravity , this theory arises by adding to the action all possible terms that are quadratic in the ricci scalar , ricci tensor , and riemann tensor . for the action 17 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ s = { 1 \\ over { 16 \\ pi g } } \\ int { \\ sqrt { - g } ( - 2 \\ lambda + r + \\ alpha { r ^ 2 } + \\ beta { r _ { \\ sigma \\ tau } } { r ^ { \\ sigma \\ tau } } + \\ gamma { r _ { \\ alpha \\ beta \\ gamma \\ delta } } { r ^ { \\ alpha \\ beta \\ gamma \\ delta } } ) { { \\ rm { d } } ^ 4 } x } $ $ \\ end { document } the field equations are 18 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { r _ { \\ kappa \\ lambda } } - { 1 \\ over 2 } r { g _ { \\ kappa \\ lambda } } + \\ alpha { k _ { \\ kappa \\ lambda } } + \\ beta { l _ { \\ kappa \\ lambda } } + \\ lambda { g _ { \\ kappa \\ lambda } } = 0 , \\ , \\ , \\ , \\ , \\ , \\ , \\ , \\ , \\ , \\ , \\ quad \\ quad \\ quad \\ quad \\ , \\ , \\ , } \\ \\ { { k _ { \\ kappa \\ lambda } } = - 2 { r _ { ; \\ kappa \\ lambda } } + 2 { g _ { \\ kappa \\ lambda } } { \\ square } r - { 1 \\ over 2 } { r ^ 2 } { g _ { \\ kappa \\ lambda } } + 2r { r _ { \\ kappa \\ lambda } } , \\ quad \\ quad \\ quad \\ quad \\ , \\ , \\ , \\ , } \\ \\ { { l _ { \\ kappa \\ lambda } } \\ equiv - 2r _ { \\ kappa ; \\ sigma \\ lambda } ^ \\ sigma + { \\ square } { r _ { \\ kappa \\ lambda } } + { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { \\ square } r - { 1 \\ over 2 } { g _ { \\ kappa \\ lambda } } { r ^ { \\ sigma \\ tau } } + 2r _ \\ kappa ^ \\ sigma { r _ { \\ sigma \\ lambda } } { . } } \\ \\ \\ end { array } $ $ \\ end { document } this class of theories is parameterized by the coefficients , , and . more recently , stein and yunes considered a more general form of quadratic gravity that includes the pontryagin term from chern - simons gravity . their action was 19 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { s \\ equiv \\ int { \\ sqrt { - g } } \\ left \\ { { \\ kappa r + { \\ alpha _ 1 } { f_1 } ( \\ theta ) { r ^ 2 } + { \\ alpha _ 2 } { f_2 } ( \\ theta ) { r _ { ab } } { r ^ { ab } } + { \\ alpha _ 3 } { f_3 } ( \\ theta ) { r _ { abcd } } { r ^ { abcd } } } \\ right . } \\ \\ { + { \\ alpha _ 4 } { f_4 } ( \\ theta ) r _ { abcd } ^ { \\ ast } { r ^ { abcd } } - \\ left . { { \\ beta \\ over 2 } [ { \\ nabla _ a } \\ theta { \\ nabla ^ a } \\ theta + 2v ( \\ theta ) ] + { { \\ mathcal l } _ { { \\ rm { matter } } } } } \\ right \\ } , \\ quad } \\ \\ \\ end { array } $ $ \\ end { document } in which the i and are coupling constants , is a scalar field , and matter is the matter lagrangian density as before . there are two versions of this theory : a non - dynamical version in which the functions are constants , and a dynamical version in which they are not . general quadratic theories are known to exhibit ghost fields negative mass - norm states that violate unitarity ( see , e.g. , for a discussion and further references ) . these occur generically , although models with an action that is a function only of r and r 4r r + r r only are ghost - free . ghost fields are also present in chern - simons modified gravity , which places strong constraints on the parameters of that model . massive - graviton theories were first considered by pauli and fierz , whose theory is generated by an action of the form 20 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { s _ { { \\ rm { pf } } } } = m_p ^ 2 \\ int { { { \\ rm { d } } ^ 4 } x } \\ left [ { - { 1 \\ over 4 } { { ( { \\ partial _ \\ mu } { h _ { \\ nu \\ rho } } ) } ^ 2 } + { 1 \\ over 4 } { { ( { \\ partial _ \\ mu } h ) } ^ 2 } - { 1 \\ over 2 } ( { \\ partial _ \\ mu } ) ( { \\ partial ^ \\ nu } h _ \\ nu ^ \\ mu ) + { 1 \\ over 2 } ( { \\ partial _ \\ mu } { h _ { \\ nu \\ rho } } ) ( { \\ partial ^ \\ nu } { h ^ { \\ mu \\ rho } } ) } \\ right . } \\ \\ { \\ left . { - { 1 \\ over 4 } { m ^ 2 } ( { h _ { \\ mu \\ nu } } { h ^ { \\ mu \\ nu } } - { h ^ 2 } ) + m_p ^ { - 2 } { t _ { \\ mu \\ nu } } { h ^ { \\ mu \\ nu } } } \\ right ] , } \\ \\ \\ end { array } $ $ \\ end { document } in which h is a rank - two covariant tensor , m and mp are mass parameters , t is the matter energy - momentum tensor , indices are raised and lowered with the minkowski metric , and h = h. the terms on the first line of this expression are generated by expanding the einstein - hilbert action to quadratic order in h. the massive graviton term is m ( hh h ) ; it contains a spin - 2 piece h and a spin - 0 piece h. this model suffers from the van dam - velten - zakharov discontinuity : no matter how small the graviton mass , the pauli - fierz theory leads to different physical predictions from those of linearized gr , such as light bending . the theory also predicts that the energy lost into gws from a binary is twice the gr prediction , which is ruled out by current binary - pulsar observations . it might be possible to circumvent these problems and recover gr in the weak - field limit by invoking the vainshtein mechanism , which relies on nonlinear effects to hide certain degrees of freedom for source distances smaller than the vainshtein radius . the massive graviton can therefore become effectively massless , recovering gr on the scale of the solar system and in binary - pulsar tests , while retaining a mass on larger scales . in such a scenario , the observational consequences for gws would be a modification to the propagation time for cosmological sources , but no difference in the emission process itself . there are also non - pauli - fierz massive graviton theories . for these , the action is the same as that in eq . ( 20 ) , but the first term on the second line ( the massive graviton term ) takes the more general form 21 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ - ( { k_1 } { h _ { \\ mu \\ nu } } { h ^ { \\ mu \\ nu } } + { k_2 } { h ^ 2 } ) , $ $ \\ end { document } where k1 and k2 are new constants of the theory that represent the squared masses of the spin - 2 and spin - 0 gravitons respectively . this theory can recover gr in the weak field , since k1 and k2 can independently be taken to zero , with modifications to weak - field effects that are on the order of the graviton mass squared . these theories are generally thought to suffer from instabilities , which arise because the spin - 0 graviton carries negative energy . however , it was shown in that the spin - 0 graviton can not be emitted without spin - 2 gravitons also being generated . the spin - 2 graviton energy is positive and greater than that of spin - 2 gravitons in gr , which compensates for the spin - 0 graviton s negative energy . the total energy emitted is therefore always positive , and it converges to the gr value in the limit that the spin - 2 graviton mass goes to zero . these alternative massive - graviton theories are therefore perfectly compatible with current observational constraints , but make very different predictions for strong gravitational fields , including the absence of horizons for black - hole spacetimes and oscillatory cosmological solutions . despite these potential problems , the existence of a massive graviton can be used as a convenient strawman for gw constraints , since the speed of gw propagation can be readily inferred from gw observations and compared to the speed of light . these proposed tests generally make no reference to an underlying theory but require only that the graviton has an effective mass and hence gws suffer dispersion . as their name suggests , there are two metrics in bimetric theories of gravity . one is dynamical and represents the tensor gravitational field ; the other is a metric of constant curvature , usually the minkowski metric , which is non - dynamical and represents a prior geometry . rosen s theory has the action 22 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ s = { 1 \\ over { 64 \\ pi g } } \\ int { { { \\ rm { d } } ^ 4 } x } \\ left [ { \\ sqrt { - \\ det ( \\ eta ) } { \\ eta ^ { \\ mu \\ nu } } { g ^ { \\ alpha \\ beta } } { g ^ { \\ gamma \\ delta } } \\ left ( { { g _ { \\ alpha \\ gamma { \\ vert } \\ mu } } { g _ { \\ alpha \\ delta { \\ vert } \\ nu } } - { 1 \\ over 2 } { g _ { \\ alpha \\ gamma { \\ vert } \\ mu } } { g _ { \\ alpha \\ delta { \\ vert } \\ nu } } } \\ right ) } \\ right ] + { s _ { { \\ rm { matter } } } } , $ $ \\ end { document } in which is the fixed flat , non - dynamical metric , g is the dynamical gravitational metric and the vertical line in subscripts denotes a covariant derivative with respect to . the final term , smatter , denotes the action for matter fields . the field equations may be written 23 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { { \\ square } _ \\ eta } { g _ { \\ mu \\ nu } } - { g ^ { \\ alpha \\ beta } } { \\ eta ^ { \\ gamma \\ delta } } { g _ { \\ mu \\ alpha { \\ vert } \\ gamma } } { g _ { \\ nu \\ beta { \\ vert } \\ delta } } = - 16 \\ pi g \\ sqrt { \\ det ( g ) / \\ det ( \\ eta ) } \\ left ( { { t _ { \\ mu \\ nu } } - { 1 \\ over 2 } { g _ { \\ mu \\ nu } } t } \\ right ) { . } $ $ \\ end { document } lightman and lee developed a bimetric theory based on a non - metric theory of gravity due to belinfante and swihart . the action for this bsll theory is 24 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ s = { 1 \\ over { 64 \\ pi g } } \\ int { { { \\ rm { d } } ^ 4 } x \\ sqrt { - \\ det ( \\ eta ) } \\ left ( { { 1 \\ over 4 } { h _ { \\ mu \\ nu { \\ vert } \\ alpha } } { h ^ { \\ mu \\ nu { \\ vert } \\ alpha } } - { 5 \\ over { 64 } } { h _ { , \\ alpha } } { h ^ { , \\ alpha } } } \\ right ) + { s _ { { \\ rm { matter } } } } , } $ $ \\ end { document } in which is the non - dynamical flat background metric and is a dynamical gravitational tensor related to the gravitational metric g via 25 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { g _ { \\ mu \\ nu } } = { { \\ left ( { 1 - { 1 \\ over { 16 } } h } \\ right ) } ^ 2 } \\ delta _ \\ mu ^ \\ alpha { \\ delta _ { \\ alpha \\ nu } } , } \\ \\ { \\ delta _ \\ nu ^ \\ mu = \\ delta _ \\ nu ^ \\ alpha \\ left ( { \\ delta _ \\ alpha ^ \\ mu - { 1 \\ over 2 } h _ \\ mu ^ \\ alpha } \\ right ) , \\ , \\ , \\ , } \\ \\ \\ end { array } $ $ \\ end { document } in which \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ delta _ \\ nu ^ \\ mu $ \\ end { document } is the kronecker delta and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ delta _ indices on and h are raised and lowered with , but on all other tensors indices are raised and lowered by g. both the rosen and bsll bimetric theories give rise to alternative gw polarization states , and have been used to motivate the construction of the parameterized post - einsteinian ( ppe ) waveform families discussed in section 5.2.2 . there is also a bimetric theory due to rastall , in which the metric is an algebraic function of the minkowski metric and of a vector field k. the action is 26 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ s = { 1 \\ over { 64 \\ pi g } } \\ int { { { \\ rm { d } } ^ 4 } x } \\ left [ { \\ sqrt { - \\ det ( g ) } f ( n ) { k _ { \\ mu ; \\ nu } } { k ^ { \\ mu ; \\ nu } } } \\ right ] + { s _ { { \\ rm { matter } } } } , $ $ \\ end { document } in which f ( n ) = n / ( n + 2 ) , n = gkk and a semicolon denotes a derivative with respect to the gravitational metric g. the metric follows from k by way of 27 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { g _ { \\ mu \\ nu } } = \\ sqrt { 1 + { \\ eta ^ { \\ alpha \\ beta } } { k _ \\ alpha } { k _ \\ beta } } ( { \\ eta _ { \\ mu \\ nu } } + { k _ \\ mu } { k _ \\ nu } ) , $ $ \\ end { document } where is again the non - dynamical flat metric . this theory has not been considered in a gw context and we will not mention it further ; more details , including the field equations , can be found in . the present consensus is that all of the compact objects observed to reside in galactic centers are supermassive black holes , described by the kerr metric of gr . this explanation follows naturally in gr from the black - hole uniqueness theorems and from a set of additional assumptions of physicality , briefly discussed below . if a deviation from kerr is inferred from gw observations , it would imply that the assumptions are violated , or possibly that gr is not the correct theory of gravity . space - based gw detectors can test black - hole kerr - ness by measuring the gws emitted by smaller compact bodies that move through the gravitational potentials of the central objects ( see section 6.2 ) . kerr - ness is also tested by characterizing multiple ringdown modes in the final black hole resulting from the coalescence of two precursors ( see section 6.3 ) . the current belief that kerr black holes are ubiquitous follows from work on mathematical aspects of gr in the middle of the 20th century . oppenheimer and snyder demonstrated that a spherically - symmetric , pressure - free distribution would collapse indefinitely to form a black hole . this result was assumed to be a curiosity due to spherical symmetry , until it was demonstrated by penrose and by hawking and penrose that singularities arise inevitably after the formation of a trapped surface during gravitational collapse . around the same time , it was proven that the black - hole solutions of schwarschild and kerr are the only static and axisymmetric black - hole solutions in gr . the assumptions that underlie the proof of the uniqueness theorem are that the spacetime is a stationary vacuum solution , that it is asymptotically flat , and that it contains an event horizon but no closed timelike curves ( ctcs ) exterior to the horizon . the lack of ctcs is needed to ensure causality , while the requirement of a horizon is a consequence of the cosmic - censorship hypothesis ( cch ) . the cch embodies this belief by stating that any singularity that forms in nature must be hidden behind a horizon ( i.e. , can not be naked ) , and therefore can not affect the rest of the universe , which would be undesirable because gr can make no prediction of what happens in its vicinity . however , the cch and the non - existence of ctcs are not required by einstein s equations , and so they could in principle be violated . besides the kerr metric , we know of many other black - hole - like solutions to einstein s equations : these are vacuum solutions with a very compact central object enclosed by a high - redshift surface . in fact , any metric can become a solution to einstein s equation : it is sufficient to insert it in the einstein tensor , and postulate the resulting matterhowever , such matter distributions will not in general satisfy the energy conditions ( see , e.g. , ) : the weak energy condition is the statement that all timelike observers in a spacetime measure a non - negative energy density , tvv 0 , for all future - directed timelike vectors v. the null energy condition modifies this condition to null observers by replacing by an arbitrary future - directed null vector k.the strong energy condition requires the ricci curvature measured by any timelike observer to be non - negative , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ ( { t _ { \\ mu \\ nu } } - t _ \\ alpha ^ \\ alpha { g _ { \\ mu \\ nu } } / 2 ) { \\ upsilon ^ \\ mu } { \\ upsilon ^ \\ nu } \\ ge 0 $ \\ end { document } , for all timelike v.the dominant energy condition is the requirement that matter flow along timelike or null world lines : that is , that \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ - t _ \\ nu ^ \\ mu { \\ upsilon ^ \\ nu } $ \\ end { document } be a future - directed timelike or null vector field for any future - directed timelike vector v. these conditions make sense on broad physical grounds ; but even after imposing them , there remain several black - hole - like solutions besides kerr . thus , space - based gw detectors offer an important test of the black - hole paradigm that follows from gr plus cch , ctc non - existence , and the energy conditions . this paradigm is especially important : putative black holes are observed to be ubiquitous in the universe , so their true nature has significant implications for our understanding of astrophysics . the weak energy condition is the statement that all timelike observers in a spacetime measure a non - negative energy density , tvv 0 , for all future - directed timelike vectors v. the null energy condition modifies this condition to null observers by replacing by an arbitrary future - directed null vector k. the strong energy condition requires the ricci curvature measured by any timelike observer to be non - negative , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ ( { t _ { \\ mu \\ nu } } - t _ \\ alpha ^ \\ alpha { g _ { \\ mu \\ nu } } / 2 ) { \\ upsilon ^ \\ mu } { \\ upsilon ^ \\ nu } \\ ge 0 $ \\ end { document } , for all timelike v. the dominant energy condition is the requirement that matter flow along timelike or null world lines : that is , that \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ - t _ \\ nu ^ \\ mu { \\ upsilon ^ \\ nu } $ \\ end { document } be a future - directed timelike or null vector field for any future - directed timelike vector v. if one or many non - kerr metrics are found , the hope is that observations will allow us to tease apart the various possible explanations : does the spacetime contain matter , such as an accretion disk , exterior to the black hole?are the cch , the no - ctc assumption , or the energy conditions violated?is the central object an exotic object , such as a boson star ? is gravity coupled to other fields ? this can lead to different black - hole solutions , although some such solutions are known ) or suspected to be unstable to generic perturbations.is the theory of gravity just different from gr ? for instance , in chern - simons gravity black holes ( to linear order in spin ) differ from kerr in their octupole moment , and this correction may produce the most significant observational signature in gw observations . while these questions are challenging , we can learn a lot by testing black - hole structure with space - based gw detectors . does the spacetime contain matter , such as an accretion disk , exterior to the black hole ? are the cch , the no - ctc assumption , or the energy conditions violated ? is the central object an exotic object , such as a boson star ? this can lead to different black - hole solutions , although some such solutions are known ) or suspected to be unstable to generic perturbations . for instance , in chern - simons gravity black holes ( to linear order in spin ) differ from kerr in their octupole moment , and this correction may produce the most significant observational signature in gw observations . the experimental search for gws began in the 1960s with joseph weber s resonant bars ( and resonant claims ) ; it has since grown into an extensive international endeavor that has produced a network of km - scale gw interferometers ( ligo , ego / virgo , geo600 , and tama / kagra ) , the proposals for space - based observatories such as lisa , and the effort to detect gws by using an array of pulsars as reference clocks . in this sectionwe briefly describe the architecture of lisa - like space - based gw observatories , beginning with the classic lisa design , and then discussing the variations studied in the 20112012 esa and nasa studies . we also discuss proposals for detectors that would operate in a higher frequency band ( between 0.1 and 10 hz ) that would bridge the gap in sensitivity between lisa - like and ground - based observatories . the most cited lisa reference is perhaps the 1998 pre - phase a mission study ; a more up - to - date review of the lisa technical architecture is given by jennrich , while the lisa science - case document describes the state of lisa science at the end of the 2000s . here we give only a quick review of the elements of the mission , referring the reader to those references for in - depth discussions . lisa consists of three identical cylindrical spacecraft , approximately 3 m wide and 1 m high , that are launched together and , after a 14 - month cruise , settle into an earth - like heliocentric orbit , 20 behind the earth . the orbit of each spacecraft is tuned slightly differently , resulting in an equilateral - triangle configuration with 510 km arms ( commensurate with the frequencies of the lisa sensitivity band ) , inclined by 60 with respect to the ecliptic . this configuration is maintained to 1 % by orbital dynamics alone for the lifetime of the mission , nominally 5 years , with a goal of 10 . in the course of a year , the center of the lisa triangle completes a full revolution on the ecliptic , while the triangle itself , as well as its normal vector , rotate through 360 . lisa detects gws by monitoring the fluctuations in the distances between freely - falling reference bodies in lisa , platinum - gold test masses housed and protected by the spacecraft . lisa uses three pairs of laser interferometric links to measure inter - spacecraft distances with errors near 10 hz . the phase shifts accumulated along different interferometer paths are proportional to an integral of gw strain along those trajectories . the test masses suffer from residual acceleration noise at a level of 310 m s , which is dominant below 3 mhz . together , the position and acceleration noises ( divided by a multiple of the armlength ) determine the lisa sensitivity to gw strain , which reaches 10 hz at frequencies of a few mhz . alternatively ( but equivalently ) , we may describe lisa as measuring the gw - induced relative doppler shifts between the local lasers on each spacecraft and the remote lasers . these doppler shifts are directly proportional to a difference of instantaneous gw strains ( as experienced by the local spacecraft at the time of measurement , and by the distant spacecraft at a time retarded by the lisa armlength divided by the speed of light ) . in either description , the 1 % breathing of the lisa constellation occurs at frequencies that are safely below the lisa measurement band . the distance measurement between the test masses along each arm is in fact split in three : an inter - spacecraft measurement between the two optical benches , and two local measurements between each test mass and its optical bench . to achieve the inter - spacecraft measurement , 2 w of 1064 - nm lightthe diffracted beams deliver only 100 pw of light to the distant spacecrafts , so they can not be reflected directly ; instead , the laser phase is measured and transponded back by modulating the frequency of the local lasers . each of the two optical assemblies on each spacecraft include the telescope and a zerodur optical bench with bonded fused - silica optical components , which implements the interspacecraft and local interferometers , as well as a few auxiliary interferometric measurements , which are needed to monitor the stability of the telescope structure , to control point - ahead corrections , and to compare the two lasers on each spacecraft . the lisa phasemeters digitize the signals from the optical - bench photodetectors at 50 mhz , and multiply them with the output of local oscillators , computing phase differences and driving the oscillators to track the frequency of the measured signal . this heterodyne scheme is needed to handle doppler shifts ( as well as laser frequency offsets ) as large as 15 mhz . because intrinsic fluctuations in the laser frequencies are indistinguishable from gws in the lisa output , laser frequency noise needs to be suppressed by several orders of magnitude , using a hierarchy of techniques : the lasers are prestabilized to local frequency references ; arm locking may be used to further stabilize the lasers using the lisa arms ( or their differences ) as stable references ; finally , time - delay interferometry is applied in post processing to remove residual laser frequency noise by algebraically combining appropriately - delayed single - link measurements , in such a way that all laser - frequency - noise terms appear as canceling pairs in the combination . with this final step , the lisa measurements combine into synthesized - interferometer observables analogous to the readings of ground - based interferometers such as ligo . the lisa disturbance reduction system ( drs ) minimizes the deviations of the test masses from free - fall trajectories , by shielding them from solar radiation pressure and interplanetary magnetic fields . on each spacecraft , the drs includes two gravitational reference sensors ( grss ) : a grs consists of a 2 - kg test mass , enclosed in an electrode housing with capacitive reading and control of test - mass position and orientation , and accompanied by additional components to cage and reposition the test mass , to maintain vacuum , and to control the accumulation of charge . the other crucial part of the drs are the micro - newton thrusters ( on each spacecraft , three clusters of four colloid or field - emission - electric propulsion systems ) , which are controlled in response to the grs readings to maintain the nominal position of the test mass with respect to the spacecraft . in addition to this active correction , test - mass acceleration noise is minimized by the accurate knowledge and correction of spacecraft self - gravity , by enforcing magnetic cleanliness , and by controlling thermal fluctuations . a version of the lisa drs with slightly lower performance will be flown and tested in lisa pathfinder , a single - spacecraft technology precursor mission . the lisa response to gws . compared to ground - based interferometers , the lisa response to gws is both richer and more complex . first , the revolution and rotation of the lisa constellation imprint a sky - position - dependent signature on long - lasting gw signals ( which for lisa include all binary signals ) : the revolution causes a time - dependent doppler shift with a period of a year , and a fractional amplitude of 10 ; the rotation introduces a 1 - year periodicity in the lisa equivalent of the ground - based - interferometer antenna patterns , endowing an incoming monochromatic gw signal with eight sidebands , separated by yr = 3.1710 hz . thus , gw signals as measured by lisa carry information regarding the position of the source ; on the other hand , data analysis must account for these effects , possibly including sky position among the parameters of matched - filtering search templates . second , the long - wavelength approximation , whereby the entire interferometer shrinks and expands as one , can not be used throughout the lisa band ; indeed , the wavelength of gws reaches the lisa armlength at a frequency of 60 mhz . as a consequence , the lisa response to a few - second impulsive gw is not a single pulse , but a collection of pulses with amplitudes and separations dependent on the sky position and polarization of the source ; the effect on high - frequency chirping signals is more subtle , but still present . this further complicates data analysis , and introduces an independent mechanism ( a triangulation of sorts ) to localize gw sources of short duration and high frequency . third , lisa is in effect three detectors in one : this can be understood most easily by considering that subsets of the three lisa arms form three separate michelson - like interferometers ( known in lisa lingo as x , y , and z ) at 120 angles . more formally , the lisa interferometric measurements can be combined into many different tdi observables ( see figure 1 ) , some resembling actual optical setups , others quite exotic , although at most three observables are independent in the sense that any other observable can be reconstructed by time - delaying and summing a generic basis of three observables . furthermore , such a basis can be chosen so that its components have uncorrelated noises , much like widely separated ground - based detectors . one of these must correspond , in effect , to x + y + z , and by symmetry it must be relatively insensitive to gws in the long - wavelength limit , providing for an independent measurement of a combination of instrument noises . lisa - like detectors measure gws by transmitting laser light between three spacecraft in triangular configuration , and comparing the optical phase of the incident lasers against reference lasers on each spacecraft . to avoid extreme requirements on laser - frequency stability over the course of the many seconds required for transmission around the triangle , data analysts will generate time - delayed linear combinations of the phase comparisons ; the combinations simulate nearly equal - delay optical paths around the sides of the triangle , and ( much like an equal - arm michelson interferometer ) they suppress laser frequency noise . many such combinations , including those depicted here , are possible , but altogether they comprise at most three independent gravitational - wave observables . lisa - like detectors measure gws by transmitting laser light between three spacecraft in triangular configuration , and comparing the optical phase of the incident lasers against reference lasers on each spacecraft . to avoid extreme requirements on laser - frequency stability over the course of the many seconds required for transmission around the triangle , data analysts will generate time - delayed linear combinations of the phase comparisons ; the combinations simulate nearly equal - delay optical paths around the sides of the triangle , and ( much like an equal - arm michelson interferometer ) they suppress laser frequency noise . many such combinations , including those depicted here , are possible , but altogether they comprise at most three independent gravitational - wave observables . the mission - concept studies ran in 20112012 by esa and nasa embrace several approaches to limiting cost . reducing mass is a broadly useful strategy , because it allows for launch on smaller , cheaper rockets , and because mass has been shown to be a good proxy for mission complexity , and therefore implementation cost . esa s ngo design envisages interferometric links along two arms rather than lisa s three , resulting in an asymmetric configuration with one full and two half spacecraft . as a consequence , only one tdi observablecan be formed , eliminating the capability of measuring two combinations of gw polarizations simultaneously . propellant may be saved by placing the spacecraft closer together ( with arms 13 mkm rather than 5 mkm ) and closer to earth . at low frequencies , the effect of shorter armlengths is to reduce the response to gws proportionally ; for the same test - mass noise , sensitivity then decreases by the same ratio . at high frequencies , the laser power available for position measurement increases as l , since beams are broadly defocused at millions of kms , improving shot noise , but not other optical noises , by a factor l ( in rms ) . as a consequence , the sweet spot of the lisa sensitivity shifts to higher frequencies , although one may instead plan for a less powerful laser , for further cost savings . spacecraft orbits that are different than lisa s , such as geocentric options , or flat configurations that lie in the ecliptic plane would also alter gw - signal modulations , and therefore parameter - estimation performance . reducing mission duration also saves money , because it reduces the cost of supporting the mission from the ground , and it allows for shorter warranties on the various subsystems . conversely , missions are made cheaper by accepting more risk of failure or underperformance , since risk is retired by extensive testing and by introducing component redundancy , both of which are expensive . the nasa study also explored replacing lisa s custom subsystems with variants already flown on other missions ( as in omega ) , or eliminating some of them altogether ( as in lagrange ) . however , the significant performance hit and additional risk incurred by such steps is not matched by correspondingly major savings , because the main cost driver for lisa - like missions is the necessity of launching and flying three ( or more ) independent spacecraft . switching to atom interferometry would make for very different mission architectures , but the nasa study finds that an atom - interferometer mission would face many of the same cost - driving constraints as a laser - interferometer mission . indeed , the overarching conclusion of the nasa study is that no technology can provide dramatic cost reductions , and that scientific performance decreases far more rapidly than cost . thus , staying the course and pursuing a modestly descoped lisa - like design , whenever programs and budgets will allow it , may yet be the most promising strategy for gw detection in space . the deci - hertz interferometer gravitational wave observatory ( decigo ) is a proposed japanese mission that would observe gws at frequencies between 1 mhz and 100 hz , reaching its best ( h 10 ) sensitivity between 0.1 and 10 hz , and thus bridging the gap between lisa - like and ground - based detectors . prior to decigo , the possibility of observing gws in the decihertz band had been studied in the context of a possible follow - up to lisa , the big bang observer ( bbo ) . the final decigo configuration ( 2024 + ) envisages four clusters in an earth - like solar orbit , each cluster consisting of three drag - free spacecraft in a triangle with 1000 - km arms . gws are measured by operating the arms as a fabry - prot interferometer , which requires keeping the arm - lengths constant , in analogy to ground - based interferometers and in contrast to lisa s transponding scheme . decigo s test masses are 100 kg mirrors , and its lasers have 10 w power . the roadmap toward decigo includes two pathfinders : the single - spacecraft decigo pathfinder consists of a 30 cm fabry - prot cavity , and it could detect binaries of 1010 m black holes if they exist near the galaxy ; next , pre - decigo would demonstrate the decigo measurement with three spacecraft and modest optical parameters , resulting in a sensitivity 10100 times worse than one of the final decigo clusters . the decigo science objectives include measuring the gw stochastic background from standard inflation ( with sensitivity down to gr 210 ) , and determining the thermal history of the universe between the end of inflation and nucleosynthesis ; searching for hypothesized primordial black holes ; characterizing dark energy by using neutron - star binaries as standard candles ( either with host redshifts , or by the effect of cosmic expansion on the inspiral phasing ) ; illuminating the formation of massive galactic black holes by observing the coalescences of intermediate - mass ( 1010 m ) systems ; constraining the structure of neutron stars by measuring their masses ( in upwards of 100000 detections per year ) ; and even searching for planets orbiting neutron - star binaries . decigo can also test alternative theories of gravity , as reviewed in : by observing neutron - star - intermediate - mass - black - hole systems , it can constrain the dipolar radiation predicted in brans - dicke scalar - tensor theory ( see section 5.1.3 in this review ) better than lisa , and four orders of magnitude better than solar - system experiments ; it can constrain the speed of gws , parametrized as the mass of the graviton ( section 5.1.2 ) three orders of magnitude better than solar - system experiments , although not as well as lisa ; by observing binaries of neutron stars and stellar - mass black holes , it can constrain the einstein - dilaton - gauss - bonnet and dynamical chern - simons theories ; it can measure the bulk ads curvature scale that modifies the evolution of black - hole binaries in the randall - sundrum ii braneworld model ; and it can even look for extra polarization modes ( section 5.1.1 ) in the stochastic gw background . in the rest of this review we concentrate on the tests of gr that will be possible with low - , rather than mid - frequency gw observatories . nevertheless , many of the studies performed for lisa - like detectorsare easily extended to the ambitious decigo program , which would probe gw sources of similar nature , but of different masses or in different phases of their evolution . the low - frequency gw band , which we define as 10 hz f 10 hz , is astrophysically appealing because it is populated by a large number of sources , which are relevant to understanding stellar evolution and stellar populations , to probing the growth and evolution massive black holes ( mbh ) and their links to galaxies , and possibly to observing the primordial universe . space - based interferometric detectors such as lisa and elisa are sensitive over this entire band . figure 2 illustrates the gw strength , as a function of gw frequency , for a variety of interesting sources classes . the lisa and elisa baseline sensitivities are overlaid , illustrating the potential reach of interferometric detectors . the area above the baseline curve is generically called discovery space ; the height of a source above the curve provides a rough estimate of the expected signal - to - noise ratio ( snr ) with which the source could be detected using matched - filtering techniques . snr and matched filtering are important concepts that underlie much of what will be discussed elsewhere in this review , so we explain them briefly in this section . figure 2the discovery space for space - based gw detectors , covering the low - frequency region of the gw spectrum , 10 hz f 0.1 hz . the discovery space is delineated by the lisa threshold sensitivity curve in black , and by the elisa sensitivity curve in red ( the curves were produced using the online sensitivity curve and source plotting website ) . this region is populated by a wealth of strong sources , often in large numbers , including mergers of mbhs , emrls of stellar - scale compact objects into mbhs , and millions of close - orbiting binary systems in the galaxy . thousands of the strongest signals from these galactic binary systems should be individually resolvable , while the combined signals of millions of them produce a stochastic background at low frequencies . these systems provide ample opportunities for astrophysical tests of gr for gravitational - field strengths that are not well characterized and studied in conventional astronomy . the discovery space for space - based gw detectors , covering the low - frequency region of the gw spectrum ,10 hz f 0.1 hz . the discovery space is delineated by the lisa threshold sensitivity curve in black , and by the elisa sensitivity curve in red ( the curves were produced using the online sensitivity curve and source plotting website ) . this region is populated by a wealth of strong sources , often in large numbers , including mergers of mbhs , emrls of stellar - scale compact objects into mbhs , and millions of close - orbiting binary systems in the galaxy . thousands of the strongest signals from these galactic binary systems should be individually resolvable , while the combined signals of millions of them produce a stochastic background at low frequencies . these systems provide ample opportunities for astrophysical tests of gr for gravitational - field strengths that are not well characterized and studied in conventional astronomy . in a particular gw search based on the evaluation of a detection , the detection snr of a gw signal is defined as the ratio of the expectation value when the signal is present to the root - mean - square average of when the signal is absent . typically the output s of the detector is modeled as the sum of a signal \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ bf { h } } ( \\ vec \\ theta ) $ \\ end { document } , depending on parameters \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ vec \\ theta } $ \\ end { document } , and of instrumental noise n. it is normally assumed that the noise is stationary and gaussian , and that it has uncorrelated frequency components ( f ) . under these assumptions , the statistical fluctuations of noise are completely determined by the one - sided power spectral density ( psd ) sh ( f ) , which is defined by the equation 28 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left \\ langle { \\ tilde n ( f ) \\ tilde n ( f ^ { \\ prime } ) ^ { \\ ast } } \\ right \\ rangle = { 1 \\ over2 } { s_h } ( f ) \\ delta ( f - f ^ { \\ prime } ) , $ $ \\ end { document } where denotes the expectation value over realizations of the noise ( also known as the ensemble average ) , and the asterisk denotes complex conjugation . this gives rise to a natural definition of an inner product on the space of possible waveform templates , 29 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ ( { { \\ bf { h } } _ 1 } { \\ vert } { { \\ bf { h } } _ 2 } ) = 2 \\ int \\ nolimits_0 ^ \\ infty \\ left [ { { { \\ tilde h_1 ^ { \\ ast } { { \\ tilde h } _ 2 } + { { \\ tilde h } _ 1 } \\ tilde h_2 ^ { \\ ast } } \\ over { { s_h } ( f ) } } } \\ right ] \\ , \\ , \\ , { \\ rm { d } } f. $ $ \\ end { document } in particular , the ( sampling ) probability of a given realization of noise n0 is just 30 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ p ( { \\ bf { n } } = { { \\ bf { n } } _ 0 } ) \\ propto \\ exp \\ left [ { - { 1 \\ over 2 } ( { { \\ bf { n } } _ 0 } { \\ vert } { { \\ bf { n } } _ 0 } ) } \\ right ] . $ $ \\ end { document } searching the data for gw signals usually involves applying a linear filter k ( t ) to compute the statistic 31 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ w = \\ int \\ nolimits _ { - \\ infty } ^ \\ infty k ( t ) s ( t ) { \\ rm { d } } t = \\ int \\ nolimits _ { - \\ infty } ^ \\ infty { \\ tilde k ^ { \\ ast } } ( f ) \\ tilde s ( f ) { \\ rm { d } } f. $ $ \\ end { document } redefining the filter by setting \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ tilde f ( f ) = \\ tilde k ( f ) { s_h } ( f ) $ \\ end { document } yields the overlap ( f | s ) . the corresponding snr is 32 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { s \\ over n } = { { ( f { \\ vert } h ) } \\ over { \\ sqrt { \\ left \\ langle { ( f { \\ vert } n ) ( f { \\ vert } n ) } \\ right \\ rangle } } } = { { ( f { \\ vert } h ) } \\ over { \\ sqrt { ( f { \\ vert } f ) } } } , $ $ \\ end { document } and from the cauchy - schwarz inequality we have 33 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ left ( { { s \\ over n } } \\ right ) ^ 2 } = { { { { ( f { \\ vert } h ) } ^ 2 } } \\ over { ( f { \\ vert } f ) } } \\ leq { { ( f { \\ vert } f ) ( h { \\ vert } h ) } \\ over { ( f { \\ vert } f ) } } = ( h { \\ vert } h ) , $ $ \\ end { document } with equality when f = h. this shows that the matched filter obtained when f = h is the optimal linear statistic to search for the signal h in noise characterized by the psd sh ( f ) . furthermore , the optimal matched - filtering snr is just \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ sqrt { ( h | h ) } $ \\ end { document } . future references to snr in this review will always refer to this mathematical object . the three main types of gw sources in the low - frequency band are massive black hole ( mbh ) binaries , extreme mass - ratio inspirals ( emris ) , and galactic binaries . these systems typically form following the merger of two galaxies , when the mbhs originally in the centers of the two pre - merger galaxies reach the center of the merged galaxy and form a binary . these binaries generate very strong gw emission and can be detected by space - based gw detectors out to cosmological distances . the signals will be observed from the time they enter the detector band , at 10 hz , until the signal cuts off after the objects have merged . the systems evolve through an inspiral , as the objects orbit one another on a nearly circular orbit of gradually shrinking radius , followed by the merger , and then the ringdown . this last phase of the signal is generated as the black - hole merger product , which is initially perturbed in a highly asymmetric state , settles down to a stationary and axisymmetric configuration . during the inspiral phase the field strength is moderate and the velocity is low compared to the speed of light , sothe system can be modeled using post - newtonian theory . during the mergerthe system is highly dynamical and requires full nonlinear modeling using numerical relativity . the final ringdown emission can then be computed using black - hole perturbation theory , since the perturbations of the object away from stationarity and axisymmetry are small . there have been several attempts to develop models that include all three phases of the emission in a single framework . the effective one - body ( eob ) model was initially developed analytically , and is based on the idea of modeling the dynamics of a binary by describing the relative motion of binary components as the motion of a test particle in an external spacetime metric ( the metric of the effective single body ) . the eob model includes a smooth transition to plunge and merger , and then a sharp transition to ringdown . the model incorporates a number of free parameters that have now been estimated by comparison to numerical - relativity simulations . ( eobnr ) model described non - spinning black holes , but the formalism has now been extended to include the effects of non - precessing spins . the other model that includes all phases of the waveform is the phenomenological inspiral - merger - ringdown ( pimr ) developed by ajith et al . this model was constructed by directly fitting an ansatz for the frequency - domain waveform , which was motivated by analytic and numerical results , to the output of numerical relativity simulations . this model has also now been extended to include the effect of non - precessing spins . emris consist of stellar - mass ( 0.550 m ) compact objects , either white dwarfs , neutron stars , or black holes , that orbit mbhs . these are expected to occur in the centers of quiescent galaxies , in which a central mbh is surrounded by a cluster of stars . interactions between these stars can put compact objects onto orbits that come very close to the mbh , leading to gravitational capture . emris are not as strong gw emitters as mbh binaries , but are expected to be observable ( if sufficiently close to us ) for the final few years before the smaller object merges with the central mbh , when the emitted gws are in the most sensitive part of the frequency range of space - based detectors . emris will also undergo inspiral , merger , and ringdown , but the signals from the latter two phases are likely to be too weak to be detected . during the inspiral , emrisare also expected to be on eccentric and inclined orbits , which colors the emitted gws with multiple frequency components . during an emri , the smaller object spends many thousands of orbits in the strong - field regime , where its velocity is a significant fraction of the speed of light , so post - newtonian waveforms are inapplicable . however , the extreme mass ratio means that black - hole perturbation theory can be used to compute waveforms , using the mass ratio as an expansion parameter . stellar binaries in our own galaxy with two compact object components will also be sources for space - based detectors if the binary period is appropriate ( 1010 s ) . the binary components must be compact to ensure that the binary can reach such periods without undergoing mass transfer . theoretical models and observational evidence suggest that there may be many millions of such binaries that are potential sources . these systems are not expected to evolve significantly over the typical lifetime of a space mission , and will therefore produce continuous and mostly monochromatic gw sources in the band of space - based detectors . for a small number of systems it will be possible to observe a linear drift in frequency over the observation time , due to either gw - driven inspiral or mass transfer . these systems remain in the weak - field regime through their observation , and their emission can be represented accurately using the quadrupole formula . in addition to what they will teach us about astrophysics , all these sources are prospective laboratories for testing gravitation . mbh binaries are strong - field systems that yield gw signals with large snrs , making signal detection and characterization less ambiguous than for weaker sources . emris provide detailed probes of mbh spacetimes , thanks to the large number of strong - field waveform cycles that will be observable from these systems . individually - resolvable compact galactic binaries can also be used to test gr , because their waveforms and evolution are well understood and easily described using model templates . in addition , many such binaries may be detectable with both gw and em observatories , providing opportunities to test the propagation of gws relative to em signals . many approaches to constraining alternative theories are proposed as null experiments , where the assumption is that gw observations will validate the predictions of gr to the level of the detector s instrumental noise . the size of residual deviations from gr is then constrained by the size of the errors in the gw measurement . however , in order to perform these null experiments , it is necessary to have accurate models for the gws predicted in gr . the appropriate modeling scheme , assuming gr and a system in vacuum , depends on the system under consideration , as described above . additional modeling complications arise from astrophysical phenomena , since tidal coupling , extended body effects , and mass transfer can all leave an impact on source evolution , complicating the interpretation of the observed gws . the very capabilities of space - based detectors also introduce complications : in contrast to the rare appearance of gw signals in the output of ground - based interferometers , the data from space - based missions will contain the superposition of millions of individual continuous signals . we expect that we will be able to resolve individually thousands of the strongest sources . thus , we must deal with problems of confusion ( where the presence of many interfering sources complicates their individual detection ) , subtraction ( where strong signals must be carefully modeled and removed from the data before weaker sources , overlapping in frequency , become visible ) , and global fit ( where the parameters of overlapping sources have correlated errors that must be varied together in searches and parameter - estimation studies ) . these issues have not escaped the attention of lisa scientists , and have been tackled both theoretically , and in a practical program of mock data challenges . all these issues in data analysis and modeling will impact the prospects for tests of gr using the observations . little work has been done to date to estimate these impacts , but we will discuss relevant studies where appropriate . in the remainder of this sectionwe will briefly describe the three principal source classes expected in the low - frequency band . for each source type , we will discuss the astrophysics of the systems , the estimated event rates for ( e ) lisa observations , their potential astrophysical implications , and their applications to testing gr , with pointers to later sections that describe the tests in more detail . we focus on the three types of source that we introduced above and that are most likely , from an astrophysical point of view , to be observed by lisa - like observatories : mbh coalescences , emris , and galactic binaries . it is possible that a space - based detector like lisa or elisa could detect other sources that could be used for tests of relativity . for instance , if intermediate - mass black holes with mass between 100m and 10m do exist , they could be observed as intermediate - mass - ratio inspirals ( imris ) when they inspiral into the mbhs in the centers of galaxies . these systems would have the potential for the same kind of tests of fundamental physics as emris , but with considerably larger snr at the same distance and hence would be observable to much greater distances . cosmological gw backgrounds might also be observed , generated by processes occurring at the tev scale in the early universe , which would provide constraints on the physics of the early universe and inflation . we refer the reader to for discussions of these sources . we regard them as somewhat more speculative than the other three source types and we do not consider them further here . most ( if not all ) galactic nuclei come to harbor a mbh during their evolution , and individual galaxies are expected to undergo multiple mergers over their lifetime . it follows that the formation of mbh binaries following galaxy mergers is an expected outcome . the mergers of such binaries will be among the strongest sources of low - frequency gws . the rate at which mbh binaries merge in the universe is uncertain at best , but these events will be detectable by lisa - like detectors to extremely large distances , probing an enormous volume of the visible universe . the detection of any mbh mergers , even at a low rate , would produce interesting astrophysical results . for a circular binary , the mass of a system that merges at a frequency fm is roughly 34 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { m_t } \\ approx { 10 ^ 5 } { m _ \\ odot } \\ left ( { { { 40 \\ , \\ , { \\ rm { mhz } } } \\ over { { f_m } } } } \\ right ) ; $ $ \\ end { document } the frequency range accessible to space - based gw detectors extends from a few 10 hz to a few 10 hz , which sets the sensitive mass range to 1010 m. mbh mergers as low - frequency gw sources . predictions for the observable population of mbh mergers are based on merger - tree structure - formation models . the overall merger rate depends on the detailed mechanisms of evolutionary growth of the mbh population . the energy budgets of active galactic nuclei suggest that mbhs could grow by efficient accretion processes , while other considerations suggest that mergers could contribute significantly to their early growth . studies of early cosmic structure indicate that mbhs form from the coalescence of many smaller seed black holes . many models based on this idea have been developed and simulated numerically . the number of events detectable by lisa was estimated to be in the range 3300 per year , with a spectrum of masses in the range 1010 m. the predicted event rate is not much different for elisa , although some of the marginally detectable events involving lighter black holes at high redshift will no longer be observable . figure 3 shows contours of constant snr ( as seen by elisa ) in the redshift - total - mass plane for equal - mass , nonspinning mbh mergers ( left panel ) and in the total - mass - mass - ratio plane for mbh mergers at a fixed redshift of z = 4 ( right panel ) . for typical events at z 4 , the snrs of elisa observations are expected to exceed 100 for total masses 510 m. for comparablemass mergers at lower redshifts , elisa observations could exceed snrs of 1000 . snrs for lisa are typically factors of 23 higher . for total mass 10 m , a significant fraction of this snr comes from the final merger and ringdown phase . the left - hand panel shows contours in the total - mass - redshift plane for equal - mass binaries , while the right - hand panel shows contours in the total - mass - mass - ratio plane for sources at redshift z = 4 . the left - hand panel shows contours in the total - mass - redshift plane for equal - mass binaries , while the right - hand panel shows contours in the total - mass - mass - ratio plane for sources at redshift z = 4 . image reproduced by permission from . several detection algorithms for mbh binaries have been studied by a number of different groups , encouraged in part by the mock lisa data challenges . these include markov chain monte carlo techniques , time - frequency analysis , particle - swarm optimization , nested sampling , and genetic algorithms . the most recent mock - data challenge included multiple spinning mbh binary signals in the same dataset , and multiple groups demonstrated their ability to recover these binaries from the lisa data stream . gw observations will directly probe the character of the black holes on scales comparable to the size of the event horizons . how the information about the black holes ( such as their spin and mass ) is encoded in the waveformis a topic of much focused research ( see , e.g. , for reviews ) . according to gr , any astrophysical black hole is fully described by just ten numbers , encoding its mass , position , momentum , and spin . correspondingly , a binary is fully described by 20 parameters , three of which , related to its center - of - mass momentum , can not be measured from the gw signal . the precision with which gw observations will be able to extract the parameters characterizing a mbh binary system has been the subject of extensive investigation . the first comprehensive study considered the lisa determination of the sky location , luminosity distance , and mass of mbh systems , using a simple model of lisa s orbital motion around the sun . later studies considered the angular resolution of detectors in precessing - plane configurations like lisa s , as well as ecliptic - plane interferometers that lie flat in the ecliptic as they orbit the sun . more recent studies have considered more complete mbh - binary waveforms with spin effects , higher harmonics , and with merger and ringdown signals , and have looked at the effect of these corrections on lisa s parameter - estimation ability . these papers indicate that observations with a lisa - like detector will be able to determine the masses of the two binary components to 0.010.1 % , the spins to 0.0010.1 % , the sky position of the binary to 110 deg , and the luminosity distance to 0.110 % . for elisa , these parameter - estimation studies witness the quality of the information that will be available to astrophysicists for the phenomenological exploration of the astrophysical character of mbh systems . of particular interestis the evolution of black - hole spins and the final spin of merger remnants , which gw observations should be able to shed some light on . in addition , the set of detected mbh merger systems will provide constraints on the formation history of mbhs . in it was shown that a detector like lisa would be able to tell with high confidence the difference between ten different models for the growth of structure in the universe . for many of the models , the difference would already be apparent after as little as three months of data collection . a similar differentiation among models would also be possible with elisa , and both detectors will also be able to constrainmbh binaries can also be used as standard candles to probe cosmological evolution . testing relativity using mbh mergers . mbh mergers are good laboratories for testing relativity because of the high snr expected for the signals and the correspondingly large volume within which they can be observed . this makes them good systems for constraining gw polarizations ( see section 5.1.1 ) since relatively weak alternative - polarization signals could in principle be detected . they are also excellent systems for testing gw - propagation effects , such as subluminal propagation speeds and the presence of parity violations , since these effects accumulate with distance and mbh binaries can be seen to very high redshifts ( see section 5.1.2 ) . mbh binaries are also well suited for generic tests of gr based on measuring the evolution of inspiral phasing and checking it for consistency with general - relativistic predictions , since the high snr allows a large number of phasing parameters to be measured ( see section 5.2 ) . mbh binaries are also the only systems for which the quasinormal ringdown radiation , generated as the highly - distorted post - merger black hole settles down into a quiescent state , will be detectable . although the amount of energy deposited into different ringdown modes is not well understood , the frequencies and decay rates of the ringdown modes are predicted precisely in gr from perturbation theory . the mass and spin of the final black hole can be measured from a single ringdown mode ; if multiple modes are detected , the system can be used to check for consistency with the kerr metric , and therefore provides a probe of black - hole structure . for a comprehensive review of black - hole ringdowns , a more detailed discussion of the use of ringdown radiation to probe black - hole structure may be found in section 6.3 . last , the space - based gw observation of mbh binaries offers an unprecedented opportunity to probe the fully - dynamic strong - field regime of gr by comparison of the observed merger signals to the predictions of numerical relativity . this is an area that has not yet been explored in any detail and so we will not discuss it further in this review . however , it is an important subject that should be carefully explored before a space - based gw detector finally becomes a reality . an emri is the gw - emitting inspiral of a stellar - mass compact object , either a black hole , neutron star or white dwarf , into a mbh in the center of a galaxy . a main - sequence star with mean density \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ bar \\ rho = 10 \\ , { \\ rm { g c } } { { \\ rm { m } } ^ { - 3 } } $ \\ end { document } will be tidally disrupted by a black hole of mass 10 m at a distance of 25 schwarzschild radii . at such separations an extra - galactic emri system will not be generating detectable amounts of gravitational radiation in the low - frequency band . the tidal - disruption radius increases with decreasing stellar density and decreasing central - black - hole mass , and the reference values used above are at the upper end of suitable values for main - sequence stars and mhz gw sources . therefore , it is not expected that the inspiral of a main - sequence star will be a candidate for an emri , with the possible exception of such sources in the galactic center , which is sufficiently nearby that radiation from an object orbiting at several tens of schwarzschild radii might be detectable . emris occur in the dense stellar clusters that are found surrounding the black holes in the cores of galaxies , and are triggered by a variety of processes : direct capture : this is thescenario , in which two - body encounters in the stellar cluster gradually perturb the compact - object orbits , changing their angular momentum . this can put a compact object onto an orbit that passes very close to the central black hole . the orbit loses energy and angular momentum in bursts of gravitational radiation emitted near periapse , and if sufficient energy is radiated , the object can be left on an orbit that is bound to the central black hole . it will then gradually inspiral into the central black hole as it loses orbital energy and angular momentum to gw emission.tidal splitting of binaries : galactic - center stellar clusters will also contain binaries , which can similarly be displaced onto orbits that pass close to the central mbh . if this happens , the binary will typically be disrupted , with one object remaining bound to the mbh and the other becoming unbound and being flung out with high velocity . if this happens to a binary containing one or two compact objects , the captured compact object will be left on a fairly tightly bound orbit a few hundred astronomical units from the mbh , and will become an emri on a nearly circular orbit . tidal stripping of giant stars : giant stars typically have a compact core surrounded by a diffuse hydrogen envelope . if such a star passes close to a mbh , the envelope can be partially or completely stripped by the tidal interaction with the mbh . this will deposit the dense core , which is essentially a white dwarf , on a close orbit about the mbh ; the system will eventually become an emri , in - situ formation : if a mbh has a massive accretion disc , the disc can become unstable to star formation . stars formed in such a way are biased toward higher masses and will therefore tend to form black - hole remnants . these remnants will be in circular , equatorial orbits around the central mbh , and will inspiral as emris under gw emission . more details on all of these processes and further references can be found in . direct capture : this is the standard scenario , in which two - body encounters in the stellar cluster gradually perturb the compact - object orbits , changing their angular momentum . this can put a compact object onto an orbit that passes very close to the central black hole . the orbit loses energy and angular momentum in bursts of gravitational radiation emitted near periapse , and if sufficient energy is radiated , the object can be left on an orbit that is bound to the central black hole . it will then gradually inspiral into the central black hole as it loses orbital energy and angular momentum to gw emission . tidal splitting of binaries : galactic - center stellar clusters will also contain binaries , which can similarly be displaced onto orbits that pass close to the central mbh . if this happens , the binary will typically be disrupted , with one object remaining bound to the mbh and the other becoming unbound and being flung out with high velocity . if this happens to a binary containing one or two compact objects , the captured compact object will be left on a fairly tightly bound orbit a few hundred astronomical units from the mbh , and will become an emri on a nearly circular orbit . tidal stripping of giant stars : giant stars typically have a compact core surrounded by a diffuse hydrogen envelope . if such a star passes close to a mbh , the envelope can be partially or completely stripped by the tidal interaction with the mbh . this will deposit the dense core , which is essentially a white dwarf , on a close orbit about the mbh ; the system will eventually become an emri , in - situ formation : if a mbh has a massive accretion disc , the disc can become unstable to star formation . stars formed in such a way are biased toward higher masses and will therefore tend to form black - hole remnants . these remnants will be in circular , equatorial orbits around the central mbh , and will inspiral as emris under gw emission . . the intrinsic rate at which emris occur depends on a lot of astrophysics that is rather poorly understood . the rate is strongly influenced by several processes , including : mass segregation : stellar encounters tend on average to lead to equipartition of energy . this means that after a two - body interaction the heavier object tends to be moving slower , and the lighter object tends to be moving faster . if this occurs for two objects around a mbh , the heavier object sinks in the potential of the mbh and the lighter object moves further out . components of the stellar distribution thus become segregated according to their mass . the more massive objects , which tend to be the black holes , end up closer to the mbh andare captured preferentially . triaxiality : the centers of galaxies tend to be approximately spherically symmetric , but on larger scales galactic nuclei can be triaxial . orbits in triaxial potentials tend to be centrophilic : they have a tendency to pass close to the center . this process can funnel stars that are further away from the mbh toward the center and hence increase the inspiral rate . resonant relaxation : in the standard relaxation picture , each encounter is random and uncorrelated , so stars undergo a random walk . the process is driven by the diffusion of energy which then leads to angular - momentum transfer . however , in a stellar cluster around a mbh , each star will be on a keplerian orbit , which is a fixed ellipse in space . the orbits of two nearby stars will thus exert correlated torques on one another , which can lead to a direct resonant evolution of the angular momentum . this process can lead to a much more rapid diffusion of orbits into the regime where they can become emris.the schwarzschild barrier : resonant relaxation relies on the orbits having commensurate radial and azimuthal frequencies , so they remain in fixed planes over multiple orbits . in the strong - field potential of a massive objectthe schwarzschild barrier refers to the boundary between orbits with and without significant precession . inside this point resonant relaxationa full description of these processes and their relative importance can be found in . the range of emri rates per galaxy reported in the literature is 11000 gyr for black holes , and 105000 gyr for white dwarfs , with most recent best - guess estimates of 400 gyr / 20 gyr / 7 gyr for black holes / white dwarfs / neutron stars . this means that after a two - body interaction the heavier object tends to be moving slower , and the lighter object tends to be moving faster . if this occurs for two objects around a mbh , the heavier object sinks in the potential of the mbh and the lighter object moves further out . components of the stellar distribution thus become segregated according to their mass . the more massive objects , which tend to be the black holes , end up closer to the mbh andtriaxiality : the centers of galaxies tend to be approximately spherically symmetric , but on larger scales galactic nuclei can be triaxial . orbits in triaxial potentials tend to be centrophilic : they have a tendency to pass close to the center . this process can funnel stars that are further away from the mbh toward the center and hence increase the inspiral rate . resonant relaxation : in the standard relaxation picture , each encounter is random and uncorrelated , so stars undergo a random walk . the process is driven by the diffusion of energy which then leads to angular - momentum transfer . however , in a stellar cluster around a mbh , each star will be on a keplerian orbit , which is a fixed ellipse in space . the orbits of two nearby stars will thus exert correlated torques on one another , which can lead to a direct resonant evolution of the angular momentum . this process can lead to a much more rapid diffusion of orbits into the regime where they can become emris . the schwarzschild barrier : resonant relaxation relies on the orbits having commensurate radial and azimuthal frequencies , so they remain in fixed planes over multiple orbits . in the strong - field potential of a massive objectthe schwarzschild barrier refers to the boundary between orbits with and without significant precession . inside this point resonant relaxationuncertainties in the event rate come not only from the intrinsic rate of capture , but also from uncertainties in the number density of black holes of suitable mass . at present , only three objects in the range 1010 m are known from kinematic measurements . using galaxy luminosity functions , the luminosity - velocity - dispersion relation and the mbh - mass - velocity dispersion relation , one infers the number density of mbhs in the lisa mass range to be roughly constant per logarithmic mass unit , and equal to a few 10 mpc . however , when black holes merge , the asymmetric radiation of linear momentum over the final few orbits imparts linear momentum ( a merger kick ) to the remnant black hole . these kicks can be large enough to eject the black hole from its host galaxy . if these black - hole merger kicks are significant for black holes merging in the centers of galaxies , the number of black holes with m 210 m may therefore be significantly depleted . emri waveforms are complex , since the orbits are expected to be both eccentric and inclined with respect to the equatorial plane of the central black hole . various algorithms have been suggested for emri detection , including hierarchical matched filtering starting with short data segments , time - frequency analysis , searches with phenomenological templates , and markov chain monte carlo searches . indeed , emris have proven to be the most difficult source to detect in the mock lisa data challenges , but in the third challenge round two groups correctly identified the three emris with the highest - mass central black holes . several challenging aspects remain unsolved , such as dealing with source confusion and detecting the emris with lower - mass central black holes , which are expected to dominate the data ; recent progress encourages confidence that these problems will be solved by the time a space - based detector is launched . assuming that a matched - filtering snr of 30 is required for emri detection , and using the previously - quoted emri rates per black hole , it was estimated that lisa could see several hundred events out to a redshift z 1 . the intrinsic rate uncertainties mean that the actual number could be anywhere from a few tens to a few thousands . most of the events will be black - hole inspirals into mbhs of mass 1010 m. the estimate for elisa is a few tens of events , although this is based on a lower snr detection threshold of 20 . ( the lower threshold is justified by the results of the mock lisa data challenges , which successfully demonstrated detection of emri events with snr of 15 , albeit with less - than - realistic signal confusion . ) emri observations will tell us about the properties of mbhs at low redshift and about the physics of nuclear stellar clusters . each emri observation can determine many of the parameters of the system , including the mass and spin of the central black hole , to accuracies of a fraction of a percent . with as few as ten emri observations , lisa would be able to constrain the slope of the mbh mass function at low redshift to 0.3 , which is the level of the current observational uncertainty . elisa would have the same capability given the same number of detections . if lisa observed as many emris as current estimates predict , the constraints on the slope would improve by an order of magnitude , although the corresponding improvement for elisa would be only a factor of two . the masses of the compact objects observed in emris will provide information about mass - segregation processes , while the overall number of events encodes information about the complicated physics that determines the event rate . finally , the eccentricities and inclinations of the observed emris will provide information on the relative efficiencies of the various channels through which emris could be formed . testing relativity using emris . emris are well suited for testing relativity for several reasons : the systems are expected to be clean since the small object is likely to be a black hole with no internal structure , and the influence of any gaseous material in the spacetime is expected to be negligible ( but see section 6 ) ; the waveforms can be computed very accurately using black - hole perturbation theory , allowing very small deviations from the model to be identified ; the inspiral is slow , meaning that many waveform cycles are generated in the strong - field regime , and can be used to test the spacetime structure ; and the waveform structure is complex , due to the expected eccentricity and inclination of the orbits , and to the intrinsic richness of dynamics in kerr ( or kerr - like ) spacetimes . the primary fundamental - physics application of emri observations is probing black - hole structure , since the emri waveforms encode a map of the spacetime geometry close to the central black hole . this can be used to test whether the central object is indeed described by the kerr metric , as we expect , or is some other kind of object . a discrepancy could indicate an astrophysical perturbation in the system , a violation of the cosmic - censorship hypothesis or of the energy conditions of gr , or even evidence for the existence of an exotic massive compact object such as a boson star . emris can also be used for tests of gw polarization ( section 5.1.1 ) , and to constrain alternative theories of gravity through detection of modifications to the inspiral rate ( see section 5.1.3 ) . the most numerous source class in the low - frequency gw band are the ultra - compact binaries of two stellar - mass compact objects : white dwarfs , neutron stars , or black holes . numerical population synthesis and theoretical studies of the highly - evolved stellar population in the galaxy predict that there will be 10 ultracompact binaries generating gws in the mhz band visible to space - based detectors like lisa or elisa . ultra - compact binaries as low - frequency gw sources . for an instrument with sensitivity similar to the classic lisa design , the complete population of compact galactic binaries would separate into two distinct observational classes : confused binaries and resolvable binaries . confused binaries are those with orbital frequencies that are close enough to other binaries in the population that they can not be readily distinguished from one another in the data ; their signals are overlapping and can not be disentangled from one another , unless one source happens to be much closer and stronger than the others . for lisa , the confused binaries make up a stochastic foreground signal from the galaxy , which would be present in the data for all frequencies below the confusion limit fc 3 mhz . various attempts have been made to estimate the spectrum of this foreground , but the final profile would also depend on details of the algorithms used to analyze the lisa data . for an instrument with a sensitivity comparable to elisa , which is approximately a factor of two worse in the relevant range , this confusion foreground would be much less prominent , and perhaps not detectable . sources below fc are binaries that happen to be nearby , and so dominate the emission near their central frequency . for sources above fc , the characteristic orbital frequencies are separated by a few frequency bin widths f 1 / tobs , where tobs is the length of observation . an instrument like lisa would be expected to resolve as many as twenty thousand individual binaries , while for elisa the number is expected to be a few thousand . among the resolvable binariesthese are binaries that are expected to be resolvable in the lisa / elisa data , but have already been detected and characterized using electromagnetic telescopes . these known binaries will provide early verification that the mission is operating correctly at the nominal sensitivity . the large number of compact binaries detectable throughout the entire galaxy makes these sources an exceptional resource to address questions about the stellar evolutionary history of the galaxy and the astrophysical dynamics of strong - field interactions in compact systems . if the confusion foreground is observed , it will be modulated by detector motion , a fact that can be used to estimate the multipole moments of the spatial distribution of binaries in the galaxy . a detector like lisa might also be able to detect the extra - galactic population of ultra - compact binaries , providing a valuable probe of its characteristics . however , an extra - galactic population is unlikely to be observed by elisa . detections of galactic binaries will be dominated by double - white - dwarf binaries , which are scarce in the galaxy , so ( e ) lisa will be in a unique position to illuminate their physics . this will shed light on their formation and evolution , including the poorly - understood phase of common - envelope evolution . this is the phase during the evolution of a binary that follows unstable mass transfer . in the frame that co - rotates with the binary , the region of space around a star where orbiting material is bound to that staris known as the roche lobe . as the orbit of a binary shrinks during inspiral , the roche lobes also shrink , and one of them can eventually become smaller than the corresponding star . at that point the outer layers of the star are no longer gravitationally bound to the star so they are lost , and this mass is transferred to the other star in the binary . the process can be stable if , when the material is transferred , the orbital radius increases , the roche lobe increases , and the star therefore no longer overflows the roche lobe . typically as the star loses mass it also becomes bigger , so stable mass transfer requires the roche lobe to increase in size more quickly than the star . mass transfer can also occur unstably if , when the material is lost , the orbit shrinks , leading to further shrinking of the roche lobe and more mass transfer ( or if the rate at which the star increases in size due to mass loss is faster than the rate at which the roche lobe increases ) . after an unstable mass - transfer event , the companion star and the core of the donor star will end up as a binary contained entirely within the material that was transferred from the donor the common envelope . subsequently , energy is transferred from the orbit to the envelope , leading to shrinking of the orbit until the objects merge or , in the case of interest for ultra - compact binaries , the envelope has been completely expelled . the physics of this phase of the evolution is very poorly understood , but it is normally characterized in terms of the amount of energy transferred between the binary and the envelope . the distribution of orbital periods and masses for ultra - compact galactic binaries will encode important clues about this process . gw observations can shed light on the fraction of mass - transferring systems ; these systems may allow coincident electromagnetic observations , making them even more precise probes of astrophysical processes such as mass transfer and tidal coupling . testing relativity using ultra - compact binaries . resolvable compact binaries offer a good laboratory for testing gr because their waveforms and evolution are well understood and easily described using model templates , and because a reasonable fraction of them will be visible both to ( e ) lisa and to electromagnetic telescopes . ultra - compact binaries will provide constraints on massive - graviton theories , either by comparison of gw - propagation delays to the observable electromagnetic signals from the binary , or by the dispersion of the gw as the binary slowly evolves . the ultra - compact binaries also provide laboratories for testing waveform evolution , and for gw polarization and dispersion studies , precisely because they evolve slowly and are easily described by post - newtonian analysis . almost since its inception , gr was understood to possess propagating , undulatory solutions gws , described at leading order by the celebrated quadrupole formula . it took several decades to establish firmly that these waves were real physical phenomena and not merely artifacts of gauge freedom . how would gw observations test the gr description of strong gravitational interactions , and possibly distinguish between gr and alternative theories ? to answer this question we need to take a quick detour through gw data analysis . at least for foreseeable detectors , individual gw signalswill typically be immersed in overwhelming noise , and therefore will need to be dug out with techniques akin to matched filtering , which by definition can only recover signals of shapes known in advance ( the templates ) , or very similar signals . a matched - filtering search is set up by first selecting a parameterized template family ( where the parameters are the source properties relevant to gw emission ) , and then filtering the detector data through discrete samplings of the family that cover the expected ranges of source parameters . the best - fitting templates correspond to the most likely parameter values , and by studying the quality of fits across parameter space it is possible to derive posterior probability densities for the parameters . after a detection , the first - order question that we may ask is whether the best - fitting gr template is a satisfactory explanation for the measured data , or whether a large residual is left that can not be explained as instrument noise , at least within our understanding of noise statistics and systematics . ( slightly more involved tests are also possible : for instance , we may divide measured signals in sections , estimate source parameters separately for each , and verify that they agree . ) if a large residual is found , many hypotheses would be a priori more likely than a violation of gr : the fitting algorithm may have failed ; another gw signal , possibly of unexpected origin , may be present in the data ; the data may reflect a rare or poorly understood instrumental glitch ; the gw source may be subject to astrophysical effects from nearby astrophysical objects , or even from intervening gravitational lenses . having ruled out such non - fundamental explanations , the only way to quantify the evidence for or against gr is to consider it alongside an alternative model to describe the data . this alternative model could be a phenomenological one ( discussed below ) or a self - consistent calculation within an alternative theory of gravity . if the alternative theories under consideration include one or more adjustable parameters that connect them to gr ( such as bd for brans - dicke theory , see section 2.1 ) , and if those parameters can be propagated through the mathematics of source modeling and gw generation , then gr template families can be enlarged to include them , and the extra parameters can be estimated from gw observations . these extra parameters may have a more phenomenological character , as would , for instance , a putative graviton mass that would affect gw propagation , without finding direct justification in a specific theory . discussed below ( section 5.1 ) fall within this class . to test gr against unconnected theories without adjustable parameters , we would instead filter the data through separate gr and alternative - theory template families , and decide which model and theory are favored by the data using bayesian model comparison , which we now describe briefly . in complex data - analysis scenarios such as those encountered for gw detectors , the techniques of bayesian inference are particularly useful for making assessments about the information content of data and for studying tests of gravitational theory , where the goal is to examine the hypothesis that the data might be described by some theory other than gr . in a traditional frequentist analysis of data , one computes the value of a statistic and then accepts or rejects a hypothesis about the data ( e.g. , that it contains a gw signal ) based on whether or not the statistic exceeds a threshold . the threshold is set on the basis of a false - alarm rate , which is a statement about how the statistic would be distributed if the experiment was repeated many times . evaluating the distribution of the statistic relies on a detailed and reliable understanding of the measurement process ( noise , instrument response , astrophysical uncertainties , etc . ) . by contrast , bayesian inference attempts to infer as much as possible about a particular set of data that has been observed , instead of making a statement about what would happen if the experiment were repeated . bayesian inference relies on the application of bayes 1763 theorem : given the observed data d and a parameterized model \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ m ( \\ vec \\ theta ) $ \\ end { document } , the theorem relates the posterior probability of the parameters given the data , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( \\ vec \\ theta | d , m ) $ \\ end { document } to the likelihood \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( d | \\ vec \\ theta , m ) $ \\ end { document } of observing the data d given the parameters \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ vec \\ theta } $ \\ end { document } , and the prior probability \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( \\ vec \\ theta / m ) $ \\ end { document } that the parameters would take that value : 35 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ p ( \\ vec \\ theta { \\ vert } d , m ) = { { p ( d { \\ vert } \\ vec \\ theta , m ) p ( \\ vec \\ theta { \\ vert } m ) } \\ over { p ( d { \\ vert } m ) } } . $ $ \\ end { document } the term \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( d | m ) = \\ int { p ( d | \\ vec \\ theta , m ) p ( \\ vec \\ theta | m ) d \\ vec \\ theta } $ \\ end { document } in the denominator is the evidence for the model m. while eq . ( 35 ) follows trivially from the definition of conditional probability , its power comes from the idea of updating the prior knowledge of a system given the results of observations . however , its practical application is complicated by the necessity of attributing priors , and the correct evaluation of likelihoods relies on the same detailed understanding of the statistical properties of the measurement noise as in the frequentist case . the evidence represents a measure of the consistency of the observed data with the model m , and can be used to compare two models ( e.g. , the gr and modified - gravity descriptions of a gw - emitting system ) by evaluating the odds ratio for model 1 over model 2 , 36 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { { \\ mathcal o } _ { 12 } } = { { p ( d { \\ vert } { m_1 } ) p ( { m_1 } ) } \\ over { p ( d { \\ vert } { m_2 } ) p ( { m_2 } ) } } , $ $ \\ end { document } where p ( m1 ) and p ( m2 ) are the prior probabilities assigned for model 1 and 2 respectively . either model would be preferred if the odds ratio is sufficiently large / small , but the decision on which hypothesis is best supported by the data is influenced by the choice of the priors , which will reflect the analyst s assessment of the relative correctness of the alternatives ( see for a discussion of this point ) . in the absence of well - defined alternative - theory foils , it may be desirable to proceed along the lines of the ppn formalism ( section 2.1 ) and immerse the gr predictions in expanded waveform families , designed to isolate differences in the resulting gw phenomenology ( section 5.2 ) . proposals to do so include schemes where the waveform - phasing post - newtonian coefficients , which are normally deterministic functions of a smaller number of source parameters , are estimated individually from the data ; the ambitiously - named parameterized post - einstein ( ppe ) framework ; and the parameterization of feynman diagrams for nonlinear graviton interactions . in section 5.3 we discuss ideas ( so far rather sparse ) to use the gws from binary mergers - ringdowns to test gr . emission of gws from the bulk motion of matter ( already emphasized above ) is contrasted toprocesses such as mass transfer , dynamical equation - of - state effects , magnetic fields , and so on . an even stronger notion of cleanness is important for the purpose of testing gr : for the best sources , the waveform signatures of alternative theories can not be reproduced by changing the astrophysical parameters of the system this orthogonality is quantified by the fitting factor between the gr and alternative - theory waveform families . fundamental bias arises from the assumption that the underlying theory in the analysis , generally taken to be gr , is the correct fundamental description for the physics being observed , which will impact the estimation of astrophysical quantities . second , many of the results presented in this section rely on the fisher - matrix formalism for evaluating the expected parameter - estimation accuracy of gw observations . as described at the beginning of section 4 , the output of a gw detector is normally modeled as a linear combination of a signal , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ bf { h } } ( \\ vec \\ theta ) $ \\ end { document } , and noise \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ bf { n } } , \\ , { \\ bf { d } } = { \\ bf { h } } ( \\ vec \\ theta ) + { \\ bf { n } } $ \\ end { document } . if the detector noise is assumed to be gaussian and stationary , the probability p ( n = n0 ) is given by eq . the likelihood \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( { \\ bf { d } } { \\ rm { | } } \\ vec \\ theta { \\ rm { , m ) } } $ \\ end { document } is just the probability that the noise takes the value \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ bf { n } } = { \\ bf { d } } - { \\ bf { h } } ( \\ vec \\ theta ) $ \\ end { document } , which is 37 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ p ( { \\ bf { d } } { \\ vert } \\ vec \\ theta , m ) \\ propto \\ exp \\ left [ { - { 1 \\ over 2 } \\ left ( { { \\ bf { d } } - { \\ bf { h } } ( \\ vec \\ theta ) \\ left \\ vert { { \\ bf { d } } - { \\ bf { h } } } \\ right . ( \\ vec \\ theta ) } \\ right ) } \\ right ] , $ $ \\ end { document } where ( a | b ) is the inner product defined in eq . ( 29 ) . writing \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ bf { d } } = h ( { { \\ vec \\ theta } _ 0 } ) $ \\ end { document } and assuming that we are close to the true parameters \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ vec \\ theta } _ 0 } $ \\ end { document } , so that we can use the linear approximation \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ h ( \\ vec \\ theta ) = h ( { { \\ vec \\ theta } _ 0 } ) + { \\ partial _ j } h \\ delta { \\ theta ^ j } + \\ cdots $ \\ end { document } , we find that at quadratic order in j 38 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ p ( { \\ bf { d } } { \\ vert } \\ vec \\ theta , m ) \\ propto \\ exp \\ left [ { - { 1 \\ over 2 } { \\ gamma _ { jk } } \\ left ( { \\ delta { \\ theta ^ j } - { { ( { \\ gamma ^ { - 1 } } ) } ^ { jl } } ( { \\ bf { n } } { \\ vert } { \\ partial _ l } h ) } \\ right ) \\ , \\ , \\ left ( { \\ delta { \\ theta ^ k } - { { ( { \\ gamma ^ { - 1 } } ) } ^ { km } } ( { \\ bf { n } } { \\ vert } { \\ partial _ m } h ) } \\ right ) } \\ right ] , $ $ \\ end { document } where 39 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ gamma _ { ij } } = \\ left ( { \\ left . { { { \\ partial h } \\ over { \\ partial { \\ theta ^ i } } } } \\ right \\ vert { { \\ partial h } \\ over { \\ partial { \\ theta ^ j } } } } \\ right ) $ $ \\ end { document } is the fisher information matrix . thus , to leading order the shape of the likelihood in the vicinity of its maximum is that of a multivariate gaussian with covariance matrix ( ) ( independent of n ) , and the variance of the one - dimensional marginalized posterior probability density of parameter is approximately ( ) ii ( no sum over i ) . this will be achieved in the limit of high signal - to - noise ratio where the errors are small and the linear approximation is valid . the fisher matrix arises also as the cramr - rao lower bound on the variance of an unbiased estimator of the waveform parameters \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ vec \\ theta } $ \\ end { document } . a full discussion of the various routes to the fisher - matrix formula and its applications may be found in . as emphasized by one of us , because the fisher matrix is built with the first derivatives of waveforms with respect to source parameters , it can only know about the close neighborhood of the true source parameters . if the estimated errors take the waveform outside that neighborhood , then the formalism is simply inconsistent and unreliable . safer , but the meaning of high is problem dependent , depending on the number of parameters that need to be estimated , on their correlation , and on the strength of their effects on the waveforms . in practice , only by carrying out a full computation of the posterior probability using , for example , monte carlo methods will it be known if the fisher matrix is providing a good guide to the shape of the posterior . however , the fisher matrix is generally much easier to compute than the full posterior , so it is widely used as a guide to the precision with which parameters of the model can be determined . in the context of testing gr , the fisher matrix can be evaluated for an expanded waveform model that includes non - gr - correction parameters , but at a set of parameters that correspond to gr . the estimated error in the correction parameter , ( ) ii , can then be interpreted as the minimal size of a correction that would be detectable with a gw observation . as will points out [ 469 , ch .10 ] , virtually any lorentz - invariant metric theory of gravity must predict gravitational radiation , but alternative theories will differ in its properties . will identifies three main properties that can be measured with gw detectors . these are the polarization , speed , and emission multipolarity ( monopole , dipole , quadrupole , etc . ) of gws in gr . in this paper , we broaden the scope of the third to include changes to the loss of energy to gws in inspiraling systems . in analogy to the three classic tests of gr ( the perihelion of mercury , deflection of light , and gravitational redshift ) we like to refer to the verification that these properties have the predicted gr values , rather than the values predicted by alternative theories , as the classic tests of gr using gws . just as ppn tests probe weak - field , slow - motion dynamics , these tests can be seen as probing the weak - field far zone , where waves have propagated far from their sources . however , the multipolarity of gws at emission and the energy that they carry away can be influenced by strong - field properties in the near zone where waves are generated . gr predicts the existence of two transverse quadrupolar polarization modes for gws ( also described as spin - 2 and tensor using the language of group theory ) , usually labeled h + and h. alternative metric theories of gravity predict as many as six polarizations ( three transverse and three longitudinal ) , corresponding to the independent electric - type components of the riemann curvature tensor , r0i0j . schematically , these components are measured by gw detectors by monitoring the geodesic deviation of nearby reference masses . the effect of different polarization modes is best illustrated by the induced motion of a ring of test particles , as in figure 4 . the response of a standard right - angle interferometer to a scalar wave is maximal when the wave propagates along one arm ; by contrast , tensor modes elicit maximal response when the wave propagates in a direction perpendicular to the plane of the detector . figure 4effect of the six possible gw polarization modes on a ring of test particles . the gw propagates in the z - direction for the upper three transverse modes , and in the x - direction for the lower three longitudinal modes . only modes ( a ) and ( b ) are possible in gr . the gw propagates in the z - direction for the upper three transverse modes , and in the x - direction for the lower three longitudinal modes . only modes ( a ) and ( b ) are possible in gr . image reproduced by permission from . direct detection . the use of gw polarization modes to test grthe sensitivity of resonant and interferometric detectors , as well as doppler - tracking and pulsar - timing measurements , to the extra modes was considered in several studies . in the most general setting , the problem of disentangling the modes has eight unknowns the time series for the six polarizations , plus two direction angles that affect the projection of the modes on the detector but only six observables , corresponding to the r0i0j components . thus , the problem is indeterminate , unless the source position is known from other observations ( such as time - of - flight delays for a long - baseline network of detectors ) , or unless we restrict gws to transverse modes on theoretical grounds . space - based observatories similar to lisa have either a single independent interferometric observable or three ( if laser links are maintained across all three arms ) . thus , a detector with three active arms could in principle discriminate a non - gr polarization mode if the direction to the source is known , or if it can be determined from the measured signal ( by means of the modulations produced by orbital motion , or by triangulation between the signals measured at the three spacecraft ) . the lisa sensitivity to alternative polarization modes was assessed in , using the full tdi response ( see section 3.1 ) . at frequencies larger than the inverse light - travel time along the arms , lisa would be ten times more sensitive to scalar - longitudinal and vector modes [ ( d ) to ( f ) in figure 4 ] than to tensor and scalar - transverse modes [ ( a ) to ( c ) in figure 4 ] , because longitudinal effects can accumulate as the lasers travel between the spacecraft . at lower frequencies , these results have not yet been used to work out the constraints that lisa could place on specific alternative theories using different types of sources . in , a generic model for a system emitting dipole radiation in addition to quadrupole radiation was constructed . the model was similar in structure to the ppe models which will be discussed in section 5.2.2 . this model included both the dipolar component of the waveform , at the orbital frequency , and modifications to the gravitational wave phasing of both the quadrupole and dipole waveform components that arise from the additional energy lost into the dipole mode . in , the model was used to determine the constraints on dipole radiation emission that would be possible using ground - based gw detectors . this demonstrated that elisa would be able to place bounds on the parameter , that describes the observed amplitude of the dipole radiation relative to the quadrupole , of 10 , and bounds on the parameter , which describes the amount of binary orbital energy lost into the dipole radiation , of 10 . the parameter affects the phase evolution and so stronger bounds would be obtained for less massive systems , for which more waveform cycles will be observed in band . these bounds are , in both cases , comparable to those from observations with the einstein telescope , one order of magnitude better than those possible with advanced ligo and one order of magnitude worse than what would be possible with lisa . finn observed that solar oscillations with 5 - to 10 - minute periods produce gravitational strains 10 at earth , possibly within reach of space - based detectors . the detectors would measure the sun s dynamical gravitational field in the transition region where it is turning into radiation . finn showed that the field develops a significant phase shift relative to solar oscillations , which depends on the gw polarizations , and which could distinguish between scalar , vector , tensor , and scalar - tensor theories of gravity . the limit placed by such observations on the brans - dicke parameter would be weaker than current bounds from solar - system tests ; on the other hand , measuring incipient gws in the transition zone makes this a novel and possibly unique test . however , we note that finn s early exploration predates our full understanding of the design and parameters of lisa - like missions , which are likely to be less sensitive to this signal . this problem was revisited in , in which the authors assessed the sensitivity of lisa to the quadrupole ( l = 2 ) low - order normal modes ( p , f and g - modes ) of the sun . they estimated that the energy in these modes would have to exceed 10 ergs to allow a lisa detection , and that the required mode energy would be even higher for elisa . galactic binaries . among the compact galactic binaries that would be detected by a lisa - like detector , several have orbital inclinations known from optical observations . for these systems we can compute the specific linear combination ( s ) of polarizations that would be appear in the data , which can then be checked for consistency . a single inconsistent binary may indicate an error in the determination of inclination or distance , but systematically inconsistent sources would hint at large non - tensor gw components . however , from general arguments the measurement accuracy for polarization amplitudes is 1 / snr ( with snr a few tens at most for galactic binaries ) , so only very large corrections to gr would be detectable in this way . in gr , gravitational radiation propagates at the speed of light : vg = c. the experimental validation of this prediction can be posed as a bound on the graviton mass mg , which is exactly zero in gr ( see for a broader context ) . however , it may be advisable to consider mg as a purely phenomenological parameter , since certain massive - graviton theories do not recover gr predictions such as light bending , as discussed in section 2.2.5 . weak - field measurements in the solar system already provide bounds on mg on the basis of the massive - graviton yukawa correction to the newtonian potential : 40 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ v ( r ) = { m \\ over r } \\ exp ( - r / { \\ lambda _ g } ) , $ $ \\ end { document } where g = h / mg is the compton wavelength of the graviton . the corresponding gw propagation speed would be given by 41 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ left ( { { { { v_g } } \\ over c } } \\ right ) ^ 2 } = 1 - { \\ left ( { { c \\ over { { f_g } { \\ lambda _ g } } } } \\ right ) ^ 2 } , $ $ \\ end { document } with fg the frequency of radiation . the best solar - system tests provide the bound g 2.810 km ( or mg 4.410 ev ) . by contrast , binary - pulsar dynamics only provide a bound mg 7.610 ev . as we discuss in this section , observations of binary gws with lisa - like detectors could provide bounds competitive with these results , with the advantage of examining a rather different sector of gravitational physics , wave propagation . two distinct methods have been proposed for this . comparing the phase of gw and em signals . this technique offers a direct comparison of the speed of gws with the speed of a radiation assumed to be null ( light itself ) . for the technique to work , sources must be observable in both light and gws , and the astrophysical delays ( if any ) between the two signals must be well understood and modeled . let the difference between the arrival times of gws and em signals be 42 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ delta t = \\ delta { t_a } - ( 1 + z ) \\ delta { t_e } , $ $ \\ end { document } where ta arises from propagation ( the very effect we wish to measure ) , and ta from different emission mechanisms or geometries . here z dlh0 / c is the redshift of the source , with the luminosity distance and h0 the value of the hubble parameter . in terms of vg , 43 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ epsilon _ g } = 1 - { { { v_g } } \\ over c } = 1 \\ times { 10 ^ { - 11 } } \\ left ( { { { 1 \\ , \\ , { \\ rm { kpc } } } \\ over { { d_l } } } } \\ right ) \\ left ( { { { \\ delta { t_a } } \\ over { 1 \\ , \\ , { \\ rm { s } } } } } \\ right ) , $ $ \\ end { document } which we relate to mg using the total relativistic energy , 44 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ epsilon _ g } \\ equiv 1 - { { { v_g } } \\ over c } = { 1 \\ over 2 } { \\ left ( { { { { m_g } { c ^ 2 } } \\ over { h { f_g } } } } \\ right ) ^ 2 } , $ $ \\ end { document } where fg is the gw frequency . the measurement of t has been considered repeatedly in the literature . the main difficulty lies with modeling the emission delay te : consider for instance am cvn binaries , where a low - mass helium donor has expanded to fill its roche lobe and is spilling mass onto a white - dwarf primary . the em signal from these systems is greatly affected by the light emitted from the overflow stream impacting the accretion disk , and the light curve oscillates as the system orbits , alternately flashing the impact point toward and away from the observer . the times of maximum emission can be taken as reference for the em phase , but how are they related to gw emission ? to evaluate this te , one may observe the compact binary at two epochs , ideally at opposite points across the earth s orbit . under the assumption that te is constant , differencing the total t measured at the two epochs leaves a measure of ta alone . however , the subtraction reduces ta to what can be accumulated across the diameter of the earth s orbit , rather than across the entire distance to the binary . as a consequence , the strongest bound from knownlisa verification binary would be g 310 km ( mg 4.610 ev ) . alternatively , one may concentrate on eclipsing compact binaries , where the light curve varies due to the mutual eclipses of the binary components , allowing the orientation geometry of the system to be precisely determined as a function of time , and yielding an accurate measure of te . in this case the measured ta is accumulated over the entire distance to the source . only one eclipsing binary that would be observable with lisa - like detectors is currently known , but an analysis of their statistically - expected population suggests that lisa would obtain a bound g 210 km ( mg 610ev ) . the reader may question whether it is appropriate to compare gravitons to photons , when the current bound on the putative mass of the photon is as high as m 210 ev . however , the much higher frequency of optical photons compared to low - frequency gravitons leads to 310 , much smaller than g 10 ( for solar - system tests ) , so a comparison based on speeds is indeed appropriate . a related test using pulsar - timing observations would compare the gw - induced phase delays accumulated by photons traveling to earth from different pulsars : the delays depend on the graviton speed through a geometric factor that alters the expected hellings - downs correlation that gws will produce in the timing of pulsars located at different positions on the sky . it might also be possible to observe simultaneous em and gw signals from mbh mergers , using the approximate position of the source known from pre - merger gw observations to guide a follow - up campaign in the em spectrum . however , the nature of possible em counterparts is extremely uncertain , so differences between the gw and em phasing could be explained by uncertainties in the modeling of the em signal . therefore , it is unlikely that constraints from these systems will be competitive with galactic - binary constraints , or with the constraints from gw dispersion discussed in the following subsection . measuring the dispersion of gravitational - wave chirps . the chirping signals emitted by inspiraling binaries contain a range of frequency components : if the graviton has mass , the components propagate at different speeds , again given by eq . this effect can be modeled in the templates used to search for binary signals by including a g dependence in the waveform phasing . in the frequency - domain representationterm ( cf ) , where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ beta = { \\ pi ^ 2 } d { { \\ mathcal m } _ c } / \\ lambda _ g ^ 2 / ( 1 + z ) $ \\ end { document } with c the binary chirp mass , f the gw frequency , d the source distance , and z the source redshift . by comparison , the leading - order term in the post - newtonian expansion of the phasing is 3/128 ( cf ) , while the g correction contributes the same power of orbital frequency as the 1pn term . for space - based detectors , the best chirp - dispersion bounds will come from massive - black - hole systems ; they improve slightly with the total binary mass and with better low - frequency ( 1010 hz ) sensitivity . however , the expected bounds depend strongly on which other physical effects ( such as spin - induced precessions , orbital eccentricity , higher waveform harmonics , the merger - ringdown phase ) will be relevant in the detected systems . as a result , a variety of predictions have appeared in the literature . bounds as strong as g a few 10 km seem possible , and would be strengthened by analyzing full catalogs of binary detections at once . instead of the chirping signals from inspiraling binaries , jones proposes a test of the gw dispersion relation using the waves from eccentric galactic binaries , which are emitted at multiple harmonics of the orbital frequencies ; if at least one galactic binary has sufficient eccentricity , jones claims sensitivity comparable to the chirp - dephasing measurements . extend the graviton - mass formalism to more general modified - gravity theories that predict violations of lorentz invariance and modified dispersion relations for gw modes , given by 45 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { e ^ 2 } = { p ^ 2 } { c ^ 2 } + m_g ^ 2 { c ^ 4 } + { \\ mathbb a } { p ^ \\ alpha } { c ^ \\ alpha } ; $ $ \\ end { document } both mg and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ mathbb a $ \\ end { document } can be constrained together , given the corresponding to specific theories , by inspiral - binary observations with ground and space - based detectors . is a conserved quantity , so left and right - circular polarized gravitational radiation propagates alike . many attempts to formulate a quantum theory of gravity require the addition of a parity - violating chern - simons ( cs ) term to the einstein - hilbert action : 46 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { s _ { { \\ rm { cs } } } } = { 1 \\ over { 64 \\ pi } } \\ int { \\ theta \\ , r ^ { \\ ast } r { { \\ rm { d } } ^ 4 } x , } \\ quad \\ , \\ , \\ , { \\ rm { where } } \\ quad r ^ { \\ ast } r = { 1 \\ over 2 } { r _ { \\ alpha \\ beta \\ gamma \\ delta } } { \\ epsilon ^ { \\ alpha \\ beta \\ gamma \\ nu } } r _ { \\ mu \\ nu } ^ { \\ gamma \\ delta } ; $ $ \\ end { document } here r is the riemann tensor , is the levi - civita tensor density , and is a ( possibly ) position - dependent function that describes the coupling of the cs field to spacetime . this correction creates a difference in the propagation equations for the left - and right - circular gw polarizations , resulting in their amplitude birefringence : one circularly - polarized state is amplified through propagation , while the other is attenuated . this effect is potentially observable with lisa - like detectors for mbh - binary inspirals at cosmological distances ( see also ) , where the amplitude birefringence generates an apparent precession of the orbital plane of the binary . the cs correction accumulates with distance , and is larger for sources at higher redshifts . orbital - plane precession will also arise from general - relativistic spin - orbit coupling , but the scaling of the precession with frequency is different , so the two effects can be distinguished , at least in principle . for an equal - mass binary with redshifted masses of 10 m that is observed plane - on at a redshift z = 15 , lisa could constrain the integrated cs contribution at the level of 10 . this is several orders of magnitude better than solar - system experiments , which furthermore can only provide local constraints . thus , lisa - like detectors may provide some hints as to the very quantum nature of gravity . in theories that do not satisfy the strong equivalence principle , the internal gravitational binding energies of bodies can create a difference between the inertial dipole moment ( i.e. , the linear momentum , which is conserved ) and the gw - generating gravitational dipole moment . thus , alternative theories of gravity generally admit dipole radiation , but it is forbidden in gr , where the two moments are identical . dipole radiation would be given at leading order by 47 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { h_d } \\ sim { 1 \\ over { { d_l } } } { { \\ rm { d } } \\ over { { \\ rm { d } } t } } ( m_1 ^ g { { \\ bf { x } } _ 1 } + m_2 ^ g { { \\ bf { x } } _ 2 } ) \\ sim { { { \\ mu ^ i } { \\ bf { v } } } \\ over { { d_l } } } \\ left ( { { { m_1 ^ g } \\ over { m_1 ^ i } } - { { m_2 ^ g } \\ over { m_2 ^ i } } } \\ right ) , $ $ \\ end { document } where x1 ,2 are the positions of the binary components , v their relative velocity , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ m _ { 1,2 } ^ i $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ m _ { 1,2 } ^ g $ \\ end { document } are their inertial and gravitational masses respectively , is the inertial reduced mass , and dl is the luminosity distance to the observer . for relativistic objects such as neutron stars ( ns ) , the gravitational binding energy can be considerable and so can be the resulting loss of energy to dipolar gws . indeed , the experimental result that the orbital decay of the binary pulsar psr1913 + 16 adhered closely to gr s quadrupole - formula prediction was sufficient to definitely falsify gr alternatives such as bimetric and stratified theories . ( amusingly , certain theories even predict that dipole radiation carries away negative energy from a binary . ) thus it is factually correct to state that the indirect detection of gws has already provided a strong test of gr . by contrast , the binary pulsar could not falsify scalar - tensor theories in this way , because these are close to gr . for instance , although dipole radiation is predicted by brans - dicke theory and changes the progression of orbital decay , the coupling parameter bd can be adjusted to approximate gr results to any desired accuracy . gr is reproduced for bd , so experimental bounds on brans - dicke are lower bounds . the hulse - taylor binary pulsar does provide a bound on bd , but one that is not competitive with solar - system tests , among which the best comes from the doppler tracking of the cassini spacecraft , which sets bd 40000 . however , other binary systems containing pulsars are known that provide constraints , which are competitive with solar - system constraints . the best constraints on scalar - tensor gravity ( and also teves gravity ) come from the pulsar - white - dwarf binary j1738 + 0333 , which provides the limit bd 25000 . lisa - like detectors can constrain bd by looking for dipole - radiation - induced modifications in the gw phasing of binary inspirals ( monopole radiation is also present , but suppressed relative to the dipole ) , as long as at least one of the binary components is not a black hole : because of the no - hair theorem , black holes can not sustain the scalar field that would lead to a differing and m ( as was recently confirmed in full numerical - relativity simulations ) . this restriction can be circumvented by having non - asymptotically flat boundary conditions for the black hole . if the scalar field is slowly varying far from the black hole ( either as a function of time or space ) then it can support a scalar field . this scenario was investigated numerically in , which found that accelerated single black holes and black - hole binaries would emit scalar radiation , in the latter case at twice the orbital frequency . if the asymptotic scalar - field gradient that supports the black - hole scalar hair is cosmological in origin , this effect will be negligible , but the possibility does exist in general . except for these considerations , the canonical source for detecting this effect is the inspiral of a neutron star into a relatively low - mass central black hole , although the number of detections of such systems is likely to be very low . early studies , based on simplified models of the waveforms and of the lisa sensitivity , estimated that for a 1.4 m neutron star inspiraling into a mbh , at fixed snr = 10 , the bd bounds would scale as 48 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ omega _ { { \\ rm { bd } } } } 2 \\ times { 10 ^ 4 } { \\ left ( { { { \\ mathcal s } \\ over { 0.3 } } } \\ right ) ^ 2 } \\ left ( { { { 100 } \\ over { \\ delta { \\ phi _ d } } } } \\ right ) { \\ left ( { { t \\ over { 1 \\ , \\ , { \\ rm { yr } } } } } \\ right ) ^ { 7/8 } } { \\ left ( { { { { { 10 } ^ 4 } { m _ \\ odot } } \\ over { { m _ \\ bullet } } } } \\ right ) ^ { 3/4 } } , $ $ \\ end { document } where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ mathcal s } $ \\ end { document } ( the sensitivity ) is a measure of the difference between the neutron - star and mbh self - gravitational binding energies per unit rest mass ; d is the dipole contribution to the gw phasing ; t is the time of observation ; and m is the mbh mass . however , this estimate is reduced by a factor of ten or more when more realistic waveforms are considered that include spin couplings , spin - induced orbital precession and eccentricity . bounds can also be derived for a massive - scalar variant of brans - dicke theory , and are of order 49 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left ( { { { { m_s } } \\ over { \\ sqrt { { \\ omega _ { { \\ rm { bd } } } } } } } } \\ right ) \\ left ( { { \\ rho \\ over { 10 } } } \\ right ) \\ lesssim { 10 ^ { - 19 } } \\ , \\ , { \\ rm { ev , } } $ $ \\ end { document } ( where is the mass of the scalar and the detection snr ) for the intermediate - mass - ratio inspiral of a ns into a black hole with mass 10 m. these results were obtained using only the leading order correction from the scalar radiation . in the authors extended this calculation to all post - newtonian orders , but in the extreme - mass - ratio limit by using the teukolsky formalism . the conclusion , that constraints on massless scalar - tensor theories from gw observations will , in general , be weaker than those from solarsystem observations , was unchanged . the reason is that scalar - tensor theories are weak - field ( infrared ) corrections to gr and are therefore largest in the weak field , so the leading order correction captures the majority of the effect . massive scalar - tensor theories were also considered in . in those theories , the primary observable consequence is the possible existence of floating orbits at which the scalar flux experiences a condition where gws scatter off the central , massive body , emerging with more energy ( extracted from the spin of the central body ) . the waves transfer that energy to the small orbiting body , increasing its orbital energy . the transition of an emri through such a floating orbit is many orders of magnitude slower than the normal emri inspiral and can last more than a hubble time . if an emri consistent with gr is observed it means that the emri not only did not pass through such a floating orbit during the timescale of the observation but could not have encountered one prior to the observation since it would not then have reached the millihertz band . therefore , an observation of a single emri can constrain the massive scalar - tensor parameter space to many orders of magnitude greater precision than current solar - system observations . a number of other suggestions have been made for low - frequency gw tests of gr that do not quite fit a modified energy - loss description . for instance , dynamical chern - simons theory introduces nonlinear modifications in the binary binding energy and dissipative corrections at the same pn order that could be observed in the late inspiral , constraining the characteristic chern - simons length scale to 1010 km , comparable to current solar - system constraints ( advanced ground - based detectors could do even better , placing bounds of 10100 km ) . corrections to the inspiral phasing will also arise if the spacetime outside the central object is not described by the kerr metric or if additional energy is lost into scalar or other forms of radiation . this has been considered for various alternative theories of gravity ; we discuss these results in detail in section 6.2.6 . gw tails , which are due to the propagation of gravitational radiation on the curved background of the emitting binary , appear at a relative 1.5 pn order ( c ) beyond the leading - order quadrupole radiation , and their observation would test the nonlinear nature of gr . ( this would be a null test of gr , since tails are included in the standard post - newtonian inspiral phasing ; see also the pn - coefficient tests discussed in section 5.2.1 . promoting newton s constant , g , to a function of time modifies both a binary s binding energy and gw luminosity , and therefore its phasing . a three - year observation of a 1010 m inspiral would constrain \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ dot g / g $ \\ end { document } to 10 yr . the infinite randall - sundrum braneworld model may predict an enormous increase in the hawking radiation emitted by black holes . the resulting progressive mass loss may be observed as an outspiral effect in the quasi - monochromatic radiation of galactic black - hole binaries , as a correction to the inspiral phasing of a black - hole binary and it would also affect the rate of emri events . the constraints on the size of extra dimensions coming from observations with lisa will , in general , be worse than those derivable from tabletop experiments . however , decigo observations of bh - ns binary mergers would be able to place a constraint about ten times better than tabletop experiments , assuming a detection rate of 10 binaries per year . as discussed above , quantitative tests of gr against modified theories of gravity evaluate how well the measured signals are fit by alternative waveform families , or ( more commonly ) by waveform families that extend gr predictions by including one or more modified - gravity parameters , such as bd for brans - dicke theory . to set up these tests we need to work within the alternative theory to derive sufficiently accurate descriptions of source dynamics , gw emission , and gw propagation . an alternative approach is to operate directly at the level of the waveforms by introducing phenomenological corrections to gr predictions : for instance , by modifying specific coefficients , or by adding extra terms . so far these have concentrated on post - newtonian waveforms for circular , adiabatic inspirals , as described by the stationary - phase approximation in the frequency domain : 50 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ tilde h ( f ) = a { f ^ { - 7/6 } } \\ exp \\ left [ { i \\ psi ( f ) + i { \\ pi \\ over 4 } } \\ right ] , $ $ \\ end { document } where f is the gw frequency ; a is the gw amplitude , given by geometrical projection factors \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ mathcal m } _ c ^ { 5/6 } / { d_l } $ \\ end { document } ( with \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ mathcal m } _ c } = { ( { m_1 } { m_2 } ) ^ { 3/5 } } / { ( { m_1 } + { m_2 } ) ^ { 1/5 } } $ \\ end { document } the chirp mass and dl the luminosity distance ) ; and for simplicity we omit the nontrivial response of space - based detectors , as well as the pn amplitude corrections . the phasing ( f ) is expanded as 51 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ psi ( f ) = 2 \\ pi f { t_c } + { \\ phi _ c } + \\ sum \\ limits _ { k \\ in { \\ mathbb z } } { \\ left [ { { \\ psi _ k } + \\ psi _ k ^ { \\ log } \\ log f } \\ right ] { f ^ { ( k - 5 ) / 3 } } } . $ $ \\ end { document } for binaries with negligible component spins , the post - newtonian phasing coefficients k are currently known up to k = 7 ( 3.5 pn order ) , and in gr they are all functions of the two masses m1 and m2 alone ( although \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ psi _ 1 } = \\ psi _ { 0 - 4 } ^ { \\ log } = \\ psi _ 7 ^ { \\ log } = 0 $ \\ end { document } , and 5 is completely degenerate with c , so it is usually omitted ) . propose a test of gr based on estimating all the k simultaneously from the measured waveform as if they were free parameters , in analogy to the post - keplerian formalism [ 293 , section 4.5 ] . the value and error estimated for each4 k , together with its pn functional form as a function of m1 and m2 , determines a region in the m1m2 plane . if gr is correct , all the regions must intersect near the true masses , as shown in figure 5 . the extent of the intersection provides a measure of how precisely gr is verified by a gw observation . a fisher - matrix analysis suggests that , for systems at the optimistic distance of 3 gpc , lisa could measure 0 to 0.1 % and 2 and 3 to 10 % , but that the fractional error on higher - order terms would be at best 1 . ( 51 ) yields differently shaped regions in the m1m2 plane , which must intersect near true mass values if gr is correct . image reproduced by permission from , copyright by aps . estimating all the binary - inspiral phasing coefficients k of eq . ( 51 ) yields differently shaped regions in the m1m2 plane , which must intersect near true mass values if gr is correct . image reproduced by permission from , copyright by aps . however , this setup may understate the power of this kind of test , since most of the estimation uncertainty in the k arises from their mutual degeneracy that is , from the fact that it is possible to vary the value of a subset of without appreciably modifying the waveform . this degeneracy should not impact the degree to which the data is deemed consistent with gr . in a follow - up paper , arun et al . propose a revised test whereby the masses are determined from 0 and 2 , while the other k ( as well as \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ psi _ 5 ^ { \\ log } $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ psi _ 6 ^ { \\ log } $ \\ end { document } ) are individually estimated and checked for consistency with gr . in this case , even for sources at z = 1 ( 7 gpc ) , all the parameters can be constrained to 1 % ( a few % for 40.1 % for 3 ) , at least for favorable mass combinations . performing parameter estimation for the eigenvectors of the kfisher matrix indicates which combinations of coefficients can be tested more accurately for gr violations . however , it is not clear what significance with regards to testing gr should be ascribed to the accuracy of measuring the k , since we do not know at what level we could expect deviations to appear . by contrast , if we were to find that , say , the n regions in the m1m2 plane do not intersect , we could make the statistically - meaningful statement that gr appears to be violated at the n level . li et al . propose a more satisfying formulation for these tests , based on bayesian model selection , which compares the bayesian evidence , given the observed data , for the pure - gr scenario against the alternative - gravity scenarios in which one or more of the k are modified . the issue of significance discussed above reappears in this context as the inherent arbitrariness in choosing prior probabilities for the k , but del pozzo et al . argue that this does not affect the efficacy of the model - comparison test in detecting gr violations . ( for a comprehensive discussion of model selection in the context of gw detection , rather than gr tests , see also . for more recent applications of this formalism to ground - based detectors , see . ) in , yunes and pretorius propose a similar but more general approach , labeling it the parameterized post - einsteinian ( ppe ) framework . for adiabatic inspirals , they propose enhancing the stationary - phase inspiral signal with extra powers of gw frequency : 52 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ tilde h ^ { { \\ rm { ppe } } } } ( f ) = { \\ tilde h ^ { { \\ rm { gr } } } } ( f ) \\ times ( 1 + \\ alpha { ( \\ pi { \\ mathcal m } f ) ^ a } ) \\ exp \\ left [ { i \\ beta { { ( \\ pi { \\ mathcal m } f ) } ^ b } } \\ right ] , $ $ \\ end { document } where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ tilde h } ^ { { \\ rm { gr } } } } $ \\ end { document } is given in eqs . while the initial suggestion in is to consider a , b , there are analytical arguments why a and b should be restricted to values a = / 3 and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ a = \\ bar a / 3 $ \\ end { document } , with \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ b = \\ bar b / 3 $ \\ end { document } , which reproduces arun s pn - coefficient scheme for \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ bar b \\ ge - 5 $ \\ end { document } . nevertheless , this representation can reproduce the leading - order effects of several alternative theories of gravity ( see table 2 ) . table 2leading - order effects of alternative theories of gravity , as represented in the ppe framework [ eq . this table is copied from , except for the two entries labeled with an asterisk . the quadratic curvature ppe exponent given in was b = 1/3 , coming from the conservative dynamics . however , it was shown in that the dissipative correction is larger , giving the value b = 7/3 quoted above . the dynamical chern - simons ppe exponent given in was b = 4/3 , which was derived using the slow - rotation metric accurate to linear order in the spin . at quadratic order in the spin , the corrections to both conservative and dissipative dynamics occur at lower post - newtonian order , giving b = 1/3 . a b brans - dicke07 / 3 parity violating10variable g ( t ) 8 / 313/3 massive graviton01 quadratic curvature07 / 3 * extra dimensions013 / 3 dynamical chern - simons +3 + 1/3 leading - order effects of alternative theories of gravity , as represented in the ppe framework [ eq . this table is copied from , except for the two entries labeled with an asterisk . the quadratic curvature ppe exponent given in was b = 1/3 , coming from the conservative dynamics . however , it was shown in that the dissipative correction is larger , giving the value b = 7/3 quoted above . the dynamical chern - simons ppe exponent given in was b = 4/3 , which was derived using the slow - rotation metric accurate to linear order in the spin . at quadratic order in the spin , the corrections to both conservative and dissipative dynamics occur at lower post - newtonian order , giving b = 1/3 . in , yunes and pretorius are motivated by the possibility of detecting gr violations , but also by the fundamental bias that would be incurred in estimating gw - source parameters using gr waveforms when modified gr is instead correct . in , cornish et al . reformulate the detection of gr violations described by ppe as a bayesian model - selection problem , similar to the pn - coefficient tests discussed in section 5.2.1 . figure 6 shows the bounds , for various fixed b , that could be set with lisa observations of m1 ,210 m binary inspirals at z = 1 and 3 . for b corresponding to modifications in higher - order pn terms ( which require strong - field , nonlinear gravity conditions to become evident ) , the bounds provided by lisa - like detectors become more competitive with respect to solar - system and binary - pulsar results ( where weak - field conditions prevail ) . figure 6constraints on phasing corrections in the ppe framework , as determined from lisa observations of 10 m massive - black - hole inspirals at z = 1 and z = 3 . the figure also includes the bounds derived from pulsar psr j0737 - 3039 , the solar - system bound on the graviton mass , and pn - coefficient bounds derived as described section 5.2.1 . the spike at b = 0 corresponds to the degeneracy between the ppe correction and the initial gw - phase parameter . constraints on phasing corrections in the ppe framework , as determined from lisa observations of 10 m massive - black - hole inspirals at z = 1 and z = 3 . the figure also includes the bounds derived from pulsar psr j0737 - 3039 , the solar - system bound on the graviton mass , and pn - coefficient bounds derived as described section 5.2.1 . the spike at b = 0 corresponds to the degeneracy between the ppe correction and the initial gw - phase parameter . ( adapted from . ) a ppe - like model including dipole radiation in addition to quadrupole radiation but no other modifications to the waveform phasing was described in and was discussed in section 5.1.1 above . the full ppe framework was extended to include all additional polarization states and higher waveform harmonics in . the final form was motivated by considering brans - dicke theory , lightman - lee theory and rosen s theory . in the most general form , eq .52 is modified to 53 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { { \\ tilde h } ^ { { \\ rm { ppe } } } } ( f ) = { { \\ tilde h } ^ { { \\ rm { gr } } } } ( f ) \\ times \\ exp \\ left [ { i \\ beta { { ( \\ pi { \\ mathcal m } f ) } ^ b } } \\ right ] \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { + ( { \\ alpha _ + } { f _ + } + { \\ alpha _ \\ times } { f _ \\ times } + { \\ alpha _ b } { f_b } + { \\ alpha _ l } { f_l } + { \\ alpha _ { { \\ rm { sn } } } } { f _ { { \\ rm { sn } } } } + { \\ alpha _ { { \\ rm { se } } } } { f _ { { \\ rm { se } } } } ) \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ times { { ( \\ pi { \\ mathcal m } f ) } ^ a } \\ exp \\ left [ { - i \\ psi _ { { \\ rm { gr } } } ^ { ( 2 ) } + i \\ beta { { ( \\ pi { \\ mathcal m } f ) } ^ b } } \\ right ] } \\ \\ { + ( { \\ alpha _ + } { f _ + } + { \\ alpha _ \\ times } { f _ \\ times } + { \\ alpha _ b } { f_b } + { \\ alpha _ l } { f_l } + { \\ alpha _ { { \\ rm { sn } } } } { f _ { { \\ rm { sn } } } } + { \\ alpha _ { { \\ rm { se } } } } { f _ { { \\ rm { se } } } } ) \\ , \\ , \\ , \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ times { { ( 2 \\ pi { \\ mathcal m } f ) } ^ c } { \\ eta ^ { { 1 \\ over 5 } } } \\ exp \\ left [ { - i \\ psi _ { { \\ rm { gr } } } ^ { ( 1 ) } + i \\ delta { { ( 2 \\ pi { \\ mathcal m } f ) } ^ b } } \\ right ] , \\ , \\ , } \\ \\ \\ end { array } $ $ \\ end { document } in which \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ psi _ { { \\ rm { gr } } } ^ { ( l ) } $ \\ end { document } is the gr phase of the lth waveform harmonic , = m1m2 / ( m1 + m2 ) is the symmetric mass ratio , and fa is the detector response to a gw in polarization mode a. the ppe parameters are ( { a } , { a } , a , , b , c , , d ) . the authors of considered two further variants of this scheme . one variant restricted the coefficients in the expansion so that they were not all independent , but were related to one another via energy conservation . the second variant included this interdependence of the parameters , and also accounted for modified propagation effects by introducing additional phase - differenceyet , this fully extended ppe scheme has not been used to explore the constraints that will be possible with space - based detectors . an analysis using a waveform model with higher harmonics and spin precession , but not alternative polarization states , was carried out in . its authors considered modifications to a subset of the phase and amplitude parameters only , which corresponded to certain post - newtonian orders and could therefore also be interpreted in terms of modifications to the pn phase coefficients as discussed in section 5.2.1 . the estimated bounds derived using this more complete waveform model were typically one to two orders of magnitude better than previous estimates for highmass systems , but basically the same for low - mass systems . this is unsurprising , since the effects of spin - precession and higher harmonics will only be important late in the inspiral . high - mass systems generate lower frequency gws and are therefore only observable for the final stages of inspiral , merger and plunge . therefore , late - time corrections are proportionally more important for those systems . for high - mass systems , the authors of estimated that lisa would be able to measure deviations in the phasing parameters to a precision n 0.1 , 10 , 50 , 500 , 1000 for n = 1 , 0 , 1 , 3/2 , 2 respectively , where n denotes the post - newtonian order , with n the coefficient of f in the waveform phase . using the same model , they also estimated that lisa could place a bound of g 110 km on the graviton compton wavelength when allowing for correlations between the different phase - modification parameters n . an extension of the ppe framework to emri systems requires a model in which orbits can be both eccentric and inclined . to develop this , vigeland et al . derive a set of near - kerr spacetime metrics that satisfy a set of conditions , including the existence of a carter - constant - like third integral of the motion , as well as asymptotic flatness . the solutions , which were previously found in , are restricted to a physically interesting subset by setting to zero any metric coefficients not required to reproduce known black - hole solutions in modified gravity , and by applying the peeling theorem ( i.e. , by requiring that the mass and spin of the black hole not be renormalized by the perturbation ) . the existence of a third integral is not a requirement for black - hole solutions , but in general its absence allows ergodic behavior in the orbits . this is discussed as a potential observable signature for deviations from gr in section 6.2.5 . however , data - analysis pipelines designed for gr waveforms may be insensitive to such qualitatively different systems . therefore the existence of a third integral is a practical assumption for interpretation once a gr - like emri has been observed . in , gair and yunes construct gravitational waveforms for emris occurring in the metrics of , based on the analytic kludge model constructed for gr emris . the waveforms provide a ppe - like model for emris that can be used in the same way as the circular ppe framework . parameter - estimation results with these ppe - emri models have not yet appeared in the literature . in , vallisneri provides a unified model - comparison performance analysis of all modified - gr tests that is valid for sufficiently - loud signals , and that yields the detection snr required for a statistically - significant detection of gr violations as a simple function of the fitting factor ff between the gr and modified - gr waveform families . the ff measures the extent to which one can reabsorb modified - gr effects by varying standard - gr parameters from their true values . vallisneri s analysis is valid in the limit of large snr , and may not be applicable to all realistic scenarios with finite snrs . an alternative to modifying frequency - domain inspiral waveforms is offered by cannella et al . they propose tests based on the effective - field - theory approach to binary dynamics , which expands the hilbert + point - mass action as a set of feynman diagrams . in this framework , gr corrections can be introduced by displacing the coefficients of interaction vertices from their gr values . for instance , multiplying the three - graviton vertex by a factor ( 1 +3 ) affects the conservative dynamics of the theory in a manner similar to the ppn parameter , but also has consequences on radiation . a similar modification to the four - graviton vertex ( parameterized by 4 ) yields effects at the second post - newtonian order , so it has no analog in ppn . argue that gr - violating values of 3 and 4 would not be detectable with gw signals , but they would instead generate small systematic errors in the estimation of standard binary parameters . however , a thorough analysis of the detectability of such deviations has not been carried out , so this conclusion may be modified in the future . according to gr , black - hole mergers are the most energetically luminous events in the universe , with l 10 l 10 erg / s , regardless of mass : at their climax , they outshine the combined power output of all the stars in the visible universe . nevertheless , second - generation ground - based gw interferometers are expected to yield the first detections of black - hole mergers , but only with rather modest snrs . by contrast , lisa - like gw detectors would observe the mergers of heavier black holes , with snrs as high as hundreds or more throughout the universe , offering very accurate measurements of the merger waveforms . massive - black - hole coalescences may feature significant spins and eccentricity , further enriching the merger phenomenology . the powerful merger events correspond to very relativistic velocities and very strong gravitational fields , so much that the pn expansion of the field equations can not be applied , and we must resort to very complex and costly numerical simulations . this makes it challenging to encode the effects of plausible gr modifications in the signal model . the first ppe paper makes such an attempt on the basis of a very crude model of merger - ringdown signals , which would probably be insufficient even to phase - match the gr signals themselves . broad efforts are currently under way to build phenomenological full - waveform ( inspiral - merger - ringdown ) models ; these involve tunable parameters that are adjusted to match the waveforms produced by numerical relativity . such parameters could also be used to encode non - gr effects in the merger - ringdown . however , at this time designing such extensions in a principled way seems daunting . a simpler approach , proposed by hughes and menou , involves the golden binaries for which system parameters can be estimated from both inspiral and ringdown gws . the former encode the parameters of the binary , while the latter encode the parameters of the final black hole formed in the merger . the functional relation of the two sets of parameters can then be compared with the predictions of numerical relativity , providing a null test of the strong - field regime of gr . hughes and menou focus on measuring the remnant s mass deficit , which equals the total energy carried away by gws , so their definition of golden binaries selects those in which the mass deficit can be estimated to better than 5 % . for lisa , these systems tend to have component masses between a few 10 m and a few 10 m , and to be found at z 23 , making up 110 % of the total merger rate depending on black - hole population models . the estimates of are based on rather simple waveform models that omit a range of physical effects , so they could be seen as conservative , given that increased waveform complexity tends to improve parameter - estimation accuracy . a more complete analysis was carried out in , but in the context of ground - based gw detectors rather than space - based detectors . it has become apparent over the last few decades that the centers of most galaxies harbor massive , dark compact objects with masses in the range 1010 m. it is clear that these objects play a very important role in the evolution of galaxies . this is exemplified by the very tight measured correlation ( the m - relation ) between the mass of the central dark objects and the velocity dispersion of stars in the central spheroid . it is generally accepted that the central dark objects are black holes described by the kerr metric , but there is presently no definitive proof of that assumption . the alternatives to the black - hole interpretation include dense star clusters , supermassive stars , magnetoids , boson stars , and fermion balls . support for the blackhole interpretation has arisen as a result of both observational and theoretical work . a short review of the evidence may be found in , although we summarize some key details in section 6.1 . as described in section 2.3 , the theoretical basis for the belief that these objects are kerr black holes has arisen from proofs that singularities inevitably form during gravitational collapse and that the kerr solution is the unique stationary and axisymmetric black - hole solution in gr . the uniqueness of the kerr solution is sometimes referred to as the no - hair theorem , since the solution is characterized by just two parameters , the black - hole mass m and angular momentum ( per unit mass ) a. the field of any vacuum , axisymmetric spacetime in gr can be characterized by a sequence of mass and current multipole moments , which we denote as ml ; and sl ; respectively . for kerr spacetimesthese multipole moments are all determined by the mass and spin via 54 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { m_l } + { \\ rm { i } } { s_l } = m { ( { \\ rm { i } } a ) ^ l } , $ $ \\ end { document } so these spacetimes require no additional independent parameters or hair . the proof of the uniqueness theorem relies on various assumptions beyond the validity of the einstein equations , so a demonstration of the non - kerr nature of astrophysical black holes could reveal exotic physics within gr . it might also indicate the presence of material in the spacetime outside the black - hole horizon , or a deviation from gr in the true theory of gravity . in this sectionwe discuss the potential of space - based low - frequency gw detectors to probe the structure of massive compact objects and the possible interpretation of these results . short reviews of the prospects for testing relativity with measurements of black - hole hair can be found in . the observational evidence for the presence of black holes in the centers of galaxies has come mainly from the studies of active galactic nuclei ( agn ) . these are known to be extremely energetic and also compact typical luminosities of 10 erg s are produced in regions less than 10 m across . the inferred agn efficiency of 10 % is much greater than the typical efficiencies of nuclear fusion processes 1 % ) , implying the need for a very deep relativistic potential . x - ray observations show variability on timescales of less than an hour , while observations of iron lines indicate the presence of gas moving at speeds of several thousand km per second . radio observations of water maser discs are consistent with keplerian motion around very compact central objects . in the spiral galaxy ngc4258 vlba observations have indicated a disc with an inner ( detected ) edge at 0.1 pc , around an object of mass 3.610 m . in addition , about 10 % of agns are associated with jets , which move at highly relativistic velocities and persist for millions of years . this requires a relativistic potential that has a preferred axis that is stable over very long timescales . agns are also remarkably similar over several decades of mass , which favors the black - hole explanation , again because kerr black holes are characterized by just m and a. in the milky way , evidence for the presence of a black hole coincident with the sgr a * radio source has come from observations of stellar motions . these are completely consistent with keplerian motion around a point source of mass m 410 m . one star , s2 , has been observed for one complete orbit and from this it has been possible to put a limit of 0.066 on the extended fraction of the central mass that could be contained between pericenter and apocenter of the orbit of s2 . at perihelion s2 was 100 au from the central object , which provides a fairly tight constraint on its compactness . electromagnetic observations can rule out stellar clusters as the explanation for the massive central objects , but some of the exotic alternatives remain . x - ray emission comes from the very inner regions of accretion discs , but uncertainties in the radius from which the emission is coming and in the mass and spin of the central object limit their utility for probing the structure of the central object . it is also possible to construct very compact boson star spacetimes that could not be ruled out from electromagnetic observations alone . by contrast , gw observations will probe the spacetime structure as the object proceeds through the inspiral and then passes the innermost stable orbit and plunges into the horizon of the central object , if a horizon exists . we discuss the prospects for using gw observations to probe black - hole structure in the following sections 6.2 and 6.3 . equation ( 54 ) tells us that a kerr black hole is uniquely characterized by two parameters . if we can measure three multipole moments of the spacetime , we can check that they are consistent with eq . if they are not , then the object can not be a kerr black hole . boson stars will typically have more independent multipole moments . in a certain class of models of rotating boson stars , the boson star can be uniquely characterized by three multipole moments , so a lisa measurement of four multipole moments could also exclude these models as an explanation of the data . gws from emris are complicated superpositions of different frequency components , found at harmonics of the three fundamental frequencies of the orbit : the orbital frequency and the frequencies of precession of the perihelion and of the orbital plane . this complex structure encodes detailed information about the spacetime in which the gws are generated . if the spacetime is assumed to be stationary and axisymmetric , it can be shown that the einstein equations reduce to a single equation , the ernst equation , for a complex scalar function , the ernst potential . by using the ernst potential and expressions due to fodor et al . that relate this potential to the multipole moments of the spacetime , ryan was able to study the properties of orbits in vacuum and axisymmetric spacetimes that possess an arbitrary set of mass and current multipole moments . however , if such an orbit is given a small radial or vertical perturbation , it will undergo small oscillations at frequencies ( the epicyclic frequencies ) that correspond to the perihelion or orbital plane precession frequencies of nearly circular and nearly equatorial orbits respectively . these frequencies can be readily computed . for the arbitrary stationary axisymmetric spacetimes considered inone finds 55 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { { { \\ omega _ r } } \\ over \\ omega } = 3 { { ( 3m \\ omega ) } ^ { { 2 \\ over 3 } } } - 4 { { { s_1 } } \\ over { { m ^ 2 } } } ( m \\ omega ) + \\ left ( { { 9 \\ over 2 } - { 3 \\ over 2 } { { { m_2 } } \\ over { { m ^ 3 } } } } \\ right ) { { ( m \\ omega ) } ^ { { 4 \\ over 3 } } } - 10 { { { s_1 } } \\ over { { m ^ 2 } } } { { ( m \\ omega ) } ^ { { 5 \\ over 3 } } } \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ { + \\ left ( { { { 27 } \\ over 2 } - 2 { { s_1 ^ 2 } \\ over { { m ^ 4 } } } - { { 21 } \\ over 2 } { { { m_2 } } \\ over { { m ^ 3 } } } } \\ right ) { { ( m \\ omega ) } ^ 2 } + \\ left ( { - 48 { { { s_1 } } \\ over { { m ^ 2 } } } - 5 { { { s_1 } { m_2 } } \\ over { { m ^ 5 } } } + 9 { { { s_3 } } \\ over { { m ^ 4 } } } } \\ right ) { { ( m \\ omega ) } ^ { { 7 \\ over 3 } } } + \\ cdots , } \\ \\ { { { { \\ omega _ z } } \\ over \\ omega } = 2 { { { s_1 } } \\ over { { m ^ 2 } } } ( m \\ omega ) + { 3 \\ over 2 } { { { m_2 } } \\ over { { m ^ 3 } } } { { ( m \\ omega ) } ^ { { 4 \\ over 3 } } } + \\ left ( { 7 { { s_1 ^ 2 } \\ over { { m ^ 4 } } } + 3 { { { m_2 } } \\ over { { m ^ 3 } } } } \\ right ) { { ( m \\ omega ) } ^ 2 } \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad \\ quad } \\ \\ \\ end { array } $ $ \\ end { document } 56 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ + \\ left ( { 11 { { { s_1 } { m_2 } } \\ over { { m ^ 5 } } } - 6 { { { s_3 } } \\ over { { m ^ 4 } } } } \\ right ) { ( m \\ omega ) ^ { { 7 \\ over 3 } } } + \\ cdots , $ $ \\ end { document } where is the angular ( ) frequency of the circular orbit being perturbed , r and z are the perihelion and orbital plane precession frequencies , and ml / sl denote the mass / current multipole moments of the spacetime metric , as in eq . ( 54 ) . the primary conclusion from eqs . ( 55 ) ( 56 ) is that the various multipole moments enter the different terms in this expansion at different orders in . the precession frequencies and orbital frequency could be extracted from gw observations , so these expansions are , in principle , observable . we can use this information to map the spacetime structure near the central object and verify that the multipole moments are consistent with the no - hair property ( 54 ) that we expect for a kerr black hole . bothrodesy or holiodesy5 by analogy with geodesy , in which observations of the motion of satellites are used to probe the gravitational field of the earth . the multipole moments are also encoded in the total orbital energy lost as the orbital frequency changes by a unit logarithmic interval 57 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } c } { { { \\ delta e ( f ) } \\ over \\ mu } = { 1 \\ over 3 } { { ( m \\ omega ) } ^ { { 2 \\ over 3 } } } - { 1 \\ over 2 } { { ( m \\ omega ) } ^ { { 4 \\ over 3 } } } + { { 20 } \\ over 9 } { { { s_1 } } \\ over { { m ^ 2 } } } { { ( m \\ omega ) } ^ { { 5 \\ over 3 } } } + \\ left ( { - { { 27 } \\ over 8 } + { { { m_2 } } \\ over { { m ^ 3 } } } } \\ right ) { { ( m \\ omega ) } ^ 2 } } \\ \\ { { { 28 } \\ over 3 } { { { s_1 } } \\ over { { m ^ 2 } } } { { ( m \\ omega ) } ^ { { 7 \\ over 3 } } } + \\ left ( { - { { 225 } \\ over { 16 } } + { { 80 } \\ over { 27 } } { { s_1 ^ 2 } \\ over { { m ^ 4 } } } + { { 70 } \\ over 9 } { { { m_2 } } \\ over { { m ^ 3 } } } } \\ right ) { { ( m \\ omega ) } ^ { { 8 \\ over 3 } } } } \\ \\ { + \\ left ( { { { 81 } \\ over 2 } { { { s_1 } } \\ over { { m ^ 2 } } } + 6 { { { s_1 } { m_2 } } \\ over { { m ^ 5 } } } - 6 { { { s_3 } } \\ over { { m ^ 4 } } } } \\ right ) { { ( m \\ omega ) } ^ 3 } + \\ cdots } \\ \\ \\ end { array } $ $ \\ end { document } a more powerful observable than the three discussed so far is the number of cycles that a trajectory spends near a particular frequency 58 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ delta { \\ mathcal n } ( f ) = { { { f ^ 2 } } \\ over { { \\ rm { d } } f / { \\ rm { d } } t } } = { f ^ 2 } { { { \\ rm { d } } e / { \\ rm { d } } f } \\ over { { \\ rm { d } } e / { \\ rm { d } } t } } , $ $ \\ end { document } but this is not as clean an observable as the precession frequencies , since it requires computing the rate of energy loss to gws in an arbitrary spacetime . ryan used this formalism in conjunction with a post - newtonian waveform model to estimate lisa s capability to measure the spacetime multipoles . he considered nearly circular and nearly equatorial inspirals , and found that lisa s ability to determine the spacetime multipoles degraded as more multipoles were included in the waveform model . the conclusion was that lisa would be able to make moderately accurate measurements of the lowest three multipole moments , but probably no more . table 3accuracy with which a lisa observation could determine the multipole moments of a spacetime decreases as more multipoles are included in the model , taken from ryan . results are shown for two typical cases , a 10 m + 10 m inspiral and a 10 m + 10 m inspiral ; in both cases the snr of the inspiral is 10 . / m m / m l max log10 ( m / m ) log10 ( s1 ) log10 ( m2 ) log10 ( s3 ) log10 ( m4 ) 13.73.5101023.02.91.832.31.91.30.741.51.31.10.11.013.32.8101022.51.00.331.20.10.80.941.00.10.81.21.8 accuracy with which a lisa observation could determine the multipole moments of a spacetime decreases as more multipoles are included in the model , taken from ryan . results are shown for two typical cases , a 10 m + 10 m inspiral and a 10 m + 10 m inspiral ; in both cases the snr of the inspiral is 10 . ryan s analysis was restricted to circular and equatorial orbits , but a counting argument suggests that spacetime mapping should still be possible for generic orbits . one complication is that the evolution of the orbital elements must also be inferred from the observation , which spoils the nice form of the expansions ( 55 ) ( 56 ) , since all the multipole moments now enter at each order of the expansion . however , this would also be true if the expansions for circular - equatorial orbits were rewritten as an expansion in some initial frequency , 0 , which would more closely represent a band - limited observation . in practice , the lowest - order multipole dominates the lowest term in the expansion and so on , which makes spacetime mapping possible in practice . the ryan formalism neatly illustrates why spacetime mapping with emris is possible , but it is not a very practical scheme . we expect that the massive central objects are indeed kerr black holes and so we really want to consider what imprint small deviations from kerr will leave on the emitted gws . a multipole - moment expansion is not a very practical way to do this , as the kerr metric has an infinite number of nonzero multipoles . several authors have adopted the approach of constructing spacetimes given by schwarzschild - kerr plus a small deviation , and have examined the properties of geodesics in those spacetimes . this was constructed by writing the metric in weyl coordinates and adding a quadrupole perturbation to the potential ( in these coordinates , the potential equation reduces to the flat - space laplacian for the ( , z ) cylindrical coordinates , which facilitates writing solutions ) . they considered two types of quadrupole perturbation : a torus around the black hole , and the addition of a point mass at each pole . in the second case , the spacetime necessarily contains line singularities running from the point masses either to infinity or to the black - hole horizon , which are needed to support the point masses . the solutions are perturbative , in that the authors kept only the terms that are linear in the deviation from schwarzschild . collins and hughes explored the properties of orbits in these spacetimes by comparing the precession and orbital frequencies of equatorial orbits in the spacetime to orbits with the same orbital parameters in kerr . they found that there were measurable differences in the perihelion precession in the strong field : for instance , at a radius of 20 m for a 2 % perturbation of the black hole , the trajectory would accumulate one radian of dephasing in 1000 orbits . collins and hughes coined the term bumpy black hole to describe spacetimes of this type . starting from the hartle - thorne metric , which is an exact solution to einstein s equations describing the spacetime outside of a slowly , rigidly rotating axisymmetric object , the authors constructed a spacetime with metric of the form \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { g _ { \\ mu \\ nu } } = g _ { \\ mu \\ nu } ^ { { \\ rm { kerr } } } + \\ varepsilon { h _ { \\ mu \\ nu } } + o ( \\ delta { m _ { l \\ ge 3 } } , \\ , \\ delta { s _ { l \\ ge 2 } } ) $ \\ end { document } , working perturbatively and keeping only the m2 perturbation in the quadrupole mass moment . a comparison of the frequencies of eccentric equatorial geodesics in the quasi - kerr spacetime to the same geodesics in the kerr spacetime indicated that it would take only 100 cycles to accumulate a / 2 phase shift for a 1 % deviation from kerr . they also computed waveform overlaps and found that , over the radiation - reaction timescale , the overlap of the waveforms for an orbit with a semilatus rectum of ten geometric radii ( gm / c ) was 20 % , 50 % , 90 % , 98 % for inspirals with mass ratio / m = 10 , 10 , 10 , 10 respectively . a third approach to analyzing deviations from the kerr spacetime was considered by gair et al . , who studied geodesic motion in a family of exact spacetimes due to manko and novikov , which include the kerr spacetime for a specific choice of parameters . by using exact solutions of the einstein field equations , they obtained solutions that were valid everywhere , in contrast to the perturbative solutions considered in , which break down near the central object . however , this scheme offers less control over the multipole moments , since it is possible to choose the lowest multipole that differs from kerr , but then the higher multipoles must also change . studied observable properties of the orbits , including the variation of the precession frequencies of nearly circular and nearly equatorial orbits as a function of orbital frequency , and the loss of the third integral of the motion ( see section 6.2.5 ) . these three papers outlined different ways to approach the problem of spacetime mapping in practice . however , none of the analyses were complete as they did not consider inspirals . collins and hughes and glampedakis and babak also ignored waveform confusion by assuming that the orbital elements were the same between the orbits under consideration . glampedakis and babak did discuss the importance of confusion and the role of the inspiral evolution in breaking such degeneracies , but no inspiral results were included in the published paper . observationally , the correct orbits to compare will be those with the same frequencies since we have no way to determine the orbital radius or eccentricity directly . assessing the confusion problem is relatively easy , but including inspiral is very hard in general , since the presence of excess multipole moments in the spacetime leads to changes in the rates of energy and angular momentum loss , which must also be included in the analysis . progress can be made in the presence of small deviations by including only the leading - order contributions to the radiation reaction from the multipole moments . this is an open area of research , although barack and cutler carried out a preliminary assessment using post - newtonian emri waveforms augmented with the leading - order contribution of an excess quadrupole moment to the precession and inspiral rates . the resulting waveforms were an improvement in comparison to ryan s analysis , since they included orbital eccentricity and inclination , and were filtered through an approximation of the lisa response . barack and cutler performed a fisher - matrix analysis of parameter - estimation uncertainties , and hence correctly accounted for the confusion issue . for this simple model , they found that a single lisa observation of the inspiral of a 10 m black hole into a 10 m , 10 m or 10 m black hole could measure the deviation from kerr of the quadrupole moment to an accuracy of ( m2 / m ) 10,10 , 10 , while simultaneously measuring the mass and spin of the central object to fractional accuracies of 10 . this suggests that a lisa - like observatory would be able to perform high - precision tests of the no - hair property of massive compact objects in galactic centers . to put these numbers in perspective , a boson star may have a quadrupole moment that is 100 times that of a kerr black hole with the same mass and spin , so it could easily be excluded . during an emrithis can be thought of as a tidal interaction the gravitational field of the small body raises a tide on the horizon that is dragged around through the orbit , leading to dissipation of energy or as energy being lost by gws falling into the black hole . fang and lovelace explored the nature of the tidal - coupling interaction by perturbing a schwarzschild black hole with a distant orbiting moon . they found that the time - dependent piece of the perturbation affected the orbit in an unambiguous way : a time - varying quadrupole moment is induced on the blackhole horizon that is proportional to the time derivative of the moon s tidal field . this quadrupole perturbation extracts energy and angular momentum from the orbit at the same rate that energy and angular momentum enter the horizon . however , the effect of the time - independent piece of the perturbation remained ambiguous . working in the regge - wheeler gauge , fang and lovelace found that this piece vanished , in contrast to a previous result by suen , who used a different gauge . this ambiguity leads to an ambiguity in the phase of the induced quadrupole moment as measured in a local asymptotic rest frame ( larf ) , although the phase of the bulge relative to the orbiting moon is well defined ( using a spacelike connection between the moon and the black hole , fang and lovelace found that the horizon shear led the horizon tidal field by an angle of 4m , where is the angular velocity of the moon ) . the ambiguity of interpretation in the larf makes it impossible to define the polarizability of the horizon or the phase shift of the tidal bulge in a body - independent way . fang and lovelace left open the possibility of developing a body - independent language to describe the response of the central object to tidal coupling , but as yet this has not happened . although the nature of the response of the central object to tidal coupling may be difficult to characterize from gw observations , the total energy lost to tidal interactions is a good observable . ryan s original theorem ignored tidal coupling , but it was later generalized by li and lovelace . they found that the gws propagating to infinity depended only very weakly on the inner boundary conditions ( i.e. , on the nature of the central object ) . this means that the spacetime s multipole structure can be inferred from the outgoing radiation field in the usual way , and hence the expected rate of orbital energy loss , assuming no energy loss into the central body , can be calculated . the rate of inspiral measures the actual rate of orbital energy loss , and the difference then gives the rate at which energy is lost to the central object , which is a direct measure of the tidal coupling . li and lovelace estimated that the ratio of the change in energy radiated to infinity due to the inner boundary condition to the energy in tidal coupling scales with the orbital velocity as v. therefore , it should be possible to simultaneously determine the spacetime structure and the tidal coupling through low - frequency gw observations . information about the central object can also come from the transition to plunge at the end of the inspiral . in a black - hole system , we expect gw emission to cut off sharply as the orbit reaches the innermost stable orbit and then plunges rapidly through the horizon . if there is no horizon in the system , the orbit may instead enter a phase where it passes into and out of the material of the central object . this was explored for boson - star models in : kesden et al . found that persistent radiation after the apparent innermost orbit could be a clear signature of the presence of a supermassive , horizonless central object in the spacetime . this analysis did not treat gravitational radiation or the interaction of the inspiraling body with the central object accurately , but it does illustrate a possible way to identify non - black - hole central objects . something similar might happen if the spacetime were to contain a naked singularity rather than a black hole : in principle , the nature of the emitted waveform after plungewould encode information about the exact nature of the central object . however , this has not yet been investigated . naked - singularity spacetimes may have very - high - redshift surfaces rather than horizons : these spacetimes would be observationally indistinguishable from black holes , unless the inspiraling object happened to move inside the high - redshift surface and then emerged , and the two epochs of radiation could be connected observationally . another example of an object that can be arbitrarily close to a schwarzschild black hole in the exterior but lack a horizon is a gravastar . these are constructed by matching a de sitter spacetime interior onto a schwarzschild exterior through a thin shell of matter , whose radius can be made arbitrarily close to the schwarzschild horizon . it was shown in that the oscillation modes of such a gravastar have quasinormal frequencies that are completely different from those of a schwarzschild black hole . therefore the absence of a horizon would be apparent if ringdown radiation was observed from such a system . in addition , the tidal perturbations that arise during the inspiral of a compact object into a gravastar during an emri can resonantly excite polar oscillations of the gravastar as the orbital frequency passes through certain values over the course of the inspiral . the excitation of these modes generates peaks in the gw - emission spectrum at frequencies that are characteristic of the gravastar , and can also show signatures of the microscopic surface of the gravastar . this process would be apparent both in the amplitude of the detected gws and in the rate of inspiral inferred from the gravitational - waveform phase , since the rate of inspiral will change significantly in the vicinity of each resonance due to the additional energy radiated in the excited quasi - normal modes . although the gravastar model used in may not be physically relevant , this work illustrates the more general fact that if the horizon of a black hole is replaced by some kind of membrane , then the modes of that membrane will inevitably be excited during an inspiral and these modes will typically be different to those of a black hole . a change in the inspiral trajectory need not be caused only by differences in the central object , but might arise due to the presence of material in the spacetime , close to the black hole but external to the event horizon . such material could influence the inspiral trajectory , and hence the emitted gws , in two distinct ways : the gravitational field of the matter could modify the multipole moments of the spacetime and hence the orbit as discussed above ; if the orbital path intersected the material , it would cause sufficient hydrodynamic drag on the object to alter the orbit . the influence of the gravitational field of external material was considered in : barausse et al . constructed a model spacetime that included both a black hole and an external torus of material very close to the central black hole . they examined the properties of orbits in two systems : one with a torus of comparable mass and spin to the central black hole ( spacetime a ) , and one with a torus of low mass , but much greater angular momentum than the central black hole ( spacetime b ) . their comparisons were based on computing equatorial geodesics and then kludge gravitational waveforms in the spacetime and in a corresponding kerr spacetime , and then evaluating the waveform overlap . orbits were identified by matching the radial and azimuthal frequencies between the orbits in the two spacetimes in two ways : altering the orbital parameters , while setting the mass and spin to be the same in the corresponding kerr spacetime ; or altering the mass and spin , while keeping the orbital parameters the same . this approach identified a confusion problem : over much of the parameter space the overlaps were very high , particularly when the second approach was adopted . b than in spacetime a , and overlaps for internal orbits between the black hole and the torus were particularly low . this work suggested that it would not be possible to distinguish between such a spacetime and a pure kerr spacetime in low - frequency gw emri observations . the need to constantly adjust the orbital parameters in order to maintain equality of frequencies would lead to a difference in the evolution of the orbit between the two spacetimes , which might break the waveform degeneracies . the torus model was also not physical , being much more compact than one would expect for agn discs . the effect of hydrodynamic drag on an emri was first considered in and was found to be negligibly small for systems likely to be of interest to space - based gravitational - wave detectors . the problem was revisited in : barausse and rezzolla considered a spacetime containing a kerr black hole surrounded by a non - self - gravitating torus with constant specific angular momentum . the hydrodynamic drag consists of a short - range part that arises from accretion , and a long - range part that arises from the gravitational interaction of the body with the density perturbations it causes in the disc . the accretion onto the small object was modeled as bondi - hoyle - lyttleton accretion6 and the long - range force using collisional dynamical - friction results from the literature . the effect of the hydrodynamical drag on the orbital evolution was computed for geodesic orbits and compared to the orbital evolution from radiation reaction for a variety of torus models , varying in mass and outer radius . the conclusion was that , for realistic outer radii for the torus , rout 10 m , the effect of hydrodynamic drag on the orbital radius and eccentricity was always small compared to radiation reaction . the hydrodynamic drag has a greater relative effect on the orbital inclination , and tends to cause orbits to become more prograde , which is opposite to the effect of radiation reaction . for rout = 10 m , the hydrodynamic drag becomes significant at r 35 m , but this radius is smaller for a more compact torus . thus , this effect will only be important for lisa if we observe a system with a very compact accretion torus , or for systems of low central mass . for the latter , the gws are detectable from orbits at larger radii where hydrodynamic drag can be important . however , the snr of such events will be low , so we are unlikely to see many of them . thus , although it seems that this effect is also marginal , this conclusion is based on considering geodesic orbits , and the possible secular build up of a drag signature over the inspiral has yet to be examined , the influence of an accretion disc on the evolution of an emri embedded within it was explored in . one of the channels that has been suggested to produce emris is the formation of stars in a disc , followed by the capture of the compact stellar remnants left after the evolution of those stars . the migration of such an emri through the accretion disc could potentially leave a measurable imprint on the gw signal . the literature distinguishes between two types of migration . in type i migration , which generally occurs for lower - mass objectsthe object excites density waves in the disc , which exert a torque on the object . in general , the torque from material exterior to the orbit is greater than that from material interior to the orbit , which causes the object to lose angular momentum and spiral inward on a timescale that is short relative to the lifetime of the disc . in type ii migration , material enters the gap on the disc s accretion timescale , driving the object and gap inwards on that timescale . considered migration in geometrically - thin and radiatively - efficient discs , in which thermal energy is radiated on a much shorter timescale than the timescale over which the material moves inward , so the disc can remain thin . such discs can be described by the shakura - sunyaev - disc model , in which the viscous stress in the disc is proportional to the total pressure at each point in the disc . these discs are known to be unstable to linear perturbations . the alternative - disc model , where stress is proportional to the gas pressure only , is stable to perturbations . yunes , kocsis et al . showed that , over a year of observation , type i migration could lead to 0.01 / 10 radian dephasings in an emri signal for both - discs and - discs , while type ii migration could lead to dephasings of 10/10 radians . the effects are larger for discs , since these can support higher surface density . for more massive central black holes 10 mthe dominant contribution is from bondi - hoyle accretion ( see footnote 6 for a description ) , while for less massive black holes of 10 m the dominant contribution is from the migration . these dephasings were computed for the same system parameters ( apart from maximizing over time and phase shifts ) , so they do not account for possible parameter correlations , but the authors argue that the migration dephasing decouples from gw parameters as the effect becomes weaker with decreasing orbital radius , while relativistic effects become stronger . the relative number of emris that will be produced in discs rather than from other channels is not well understood . however , it will be straightforward to identify such emris , which will be circular and equatorial , to look for and constrain effects of this type . another important question that has not yet been addressed is how to distinguish the effect of external material from a difference in the structure of the central object . if the orbit does not intersect the material , such identification would come from the variation in the effect over the inspiral if the change in the multipole structure comes from material , then at some stage the object would pass inside the matter , and the qualitative effect on the inspiral would be different from that of a central object with an unusual multipole structure . if the orbit does intersect the material , then the spacetime - mapping analysis described above no longer applies , since the geroch - hansen multipole decomposition applies to vacuum spacetimes only . if this decomposition could be generalized to nonvacuum axisymmetric spacetimes , then low - frequency gw observation could potentially recover not only the spacetime metric but also the structure of the external material . it would then be possible to verify that this matter obeys the various energy conditions ( see section 2.3 ) . an independent indicator of the presence of material in the spacetime would come from the observation of an electromagnetic counterpart to an emri event . for instance , if an inspiraling black hole was moving through an accretion disc , there might be emission from the material that was accreted onto the inspiraling object or from shocks formed in the disc . again , this has not been explored , although it is likely , given the poor sky - position determination of emri events in gw observations , that it would not be possible to conclusively identify such a weak electromagnetic signature in coincidence with a gw event . the presence of exotic matter outside a black hole , in the form of a cloud of axions , was discussed in . the presence of large numbers of light axions would be one consequence of extra dimensions in string theory , so the detection of an axion cloud would provide strong evidence in support of their existence . the axion cloud would modify the motion of an inspiraling black hole in a similar way to regular matter , although estimates for the precision of measurements possible with future gw detectors have not yet been carried out . the passage of an emri through the cloud could also lead to its disruption , which may rule out the cloud as a possible explanation for any observed deviations , but further theoretical work is required to properly quantify these processes . if multiple states with the same orbital momenta l and magnetic moments m but different principal quantum numbers n are occupied , transitions between these states can generate gws with characteristic strain 59 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ h \\ sim { 10 ^ { - 22 } } { \\ alpha ^ 2 } { ( { \\ epsilon _ 0 } { \\ epsilon _ 1 } ) ^ { 1/2 } } \\ left ( { { { 10 \\ , { \\ rm { mpc } } } \\ over r } } \\ right ) \\ , \\ , \\ left ( { { { { m _ { { \\ rm { bh } } } } } \\ over { 2 \\ , { m _ \\ odot } } } } \\ right ) $ $ \\ end { document } for a black hole of mass mbh at a distance r. the pre - factor ( 01 ) depends on the axion masses and coupling . the axions can also undergo annihilations , which generate gws with very similar characteristic strains 60 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ h \\ sim { 10 ^ { - 22 } } { \\ alpha ^ 7 } \\ epsilon \\ left ( { { { 10 \\ , { \\ rm { mpc } } } \\ over r } } \\ right ) \\ , \\ , \\ left ( { { { { m _ { { \\ rm { bh } } } } } \\ over { 2 \\ , { m _ \\ odot } } } } \\ right ) . $ $ \\ end { document } in both cases the frequency depends on the black - hole mass in the usual way f 1 / mbh , with typical values for 2 m black holes of 100 hz and 30 khz respectively . both elisa and ligo could place interesting constraints on the axion parameter space through ( non ) detections of these events . finally , the self - interactions in the axion cloud could eventually lead to the collapse of the cloud in aexplosion , which would generate gws with strain 61 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ h \\ sim { 10 ^ { - 17 } } \\ left ( { { \\ epsilon \\ over { { { 10 } ^ { - 4 } } } } } \\ right ) \\ , \\ , \\ left ( { { { 100 \\ , { \\ rm { mpc } } } \\ over r } } \\ right ) \\ , \\ , \\ left ( { { { { m _ { { \\ rm { bh } } } } } \\ over { { { 10 } ^ 8 } \\ , { m _ \\ odot } } } } \\ right ) $ $ \\ end { document } and frequency c / gmbh . recent calculations suggest that a bosenova from the milky way black hole at saggitarius a * would be marginally detectable by lisa . the bosenova explosion comes about due to a super - radiant interaction between the cloud of particles and the central black hole , which extracts rotational energy from the black hole and transfers it to the cloud of particles . recent results on these super - radiant instabilities can be found in . in the observable signatures of the presence of a cloud of bosons outside a massive compact object was considered . it was shown that the motion of a particle through the cloud would be dominated by boson accretion rather than by gravitational radiation reaction . during this accretion - dominated phase , the frequency and amplitude of the gravitational - wave emission is nearly constant in the late stages of inspiral . the authors also considered inspirals exterior to the boson cloud , and found that resonances could occur when the orbital frequency matched the characteristic frequency associated with the characteristic mass of the bosonic particles . these resonances could lead to significant , detectable deviations in the phase of the emitted gws . perturbations to the emri trajectory could also arise from the gravitational influence of distant objects , such as other stars or a second mbh . at present , it is thought to be very unlikely that a second star or compact object would be present in the spacetime sufficiently close to the emri to leave a measurable imprint on the trajectory , although detailed calculations for this scenario have not been carried out . however , if the mbh that was the host of the emri was in a binary with a second mbh , this could perturb the trajectory by a detectable amount . the primary observable effect is a doppler shift of the gw signal , which arises due to the acceleration of the center of mass of the emri system relative to the observer . it was estimated that , for typical emri systems , the presence of a second black hole within a few tenths of a parsec would lead to a measurable imprint in the signal . the frequency scaling of the doppler effect differs from the scaling of the post - newtonian terms in the unaccelerated waveform , which suggests that this effect will be distinguishable in gw observations . the magnitude of the leading - order doppler effect scales as msec / r , where msec is the mass of the perturbing black hole , and r is its distance . if the second object is within a few hundredths of a parsec , higher - order time derivatives could also be measured from the gw observations . these scale differently with msec and r , which would in principle allow the mass and distance of the perturber to be measured from the emri data . the probability that a second black hole would be within a tenth of a parsec of a system containing an emri is difficult to assess . at redshifts z 1 , at any given time a few percent of milky way - like galaxieswill be involved in a merger , which suggests an upper limit of a few percent of emris that could have perturbing companions . however , there is uncertainty as to how long the black - hole binary will spend at radii of a few tenths of a parsec following a merger , and it is plausible that the presence of a second black hole would increase the emri rate by perturbing stars onto orbits that pass close to the other black hole , introducing an observational bias in favor of these systems . given these uncertainties , the possibility of a distant perturber will have to be accounted for in the analysis , and , if it is observed in some systems , lisa - like detectors could indirectly inform us of the processes that drive mbh mergers . the gravitational influence of a second stellar mass black hole on the evolution of an emri were considered in . it was shown that a second black hole with a semi - major axis of 10 pc could influence the orbital parameters of an emri ongoing in the same galaxy and already in the low - frequency gw band . it was estimated that in 1 % of emris a second black hole could be within the required distance . however , the timescale of the chaotic motion was 10 s , which is much longer than a typical low - frequency observation , and the system considered in had an orbital period of 610 s , which would probably not yet be detectable by lisa - like detectors . on the timescale of a gw mission , the effect would probably manifest itself as a linear drift in the orbital parameters , and therefore it is unlikely that this effect would prevent the detection of an emri signal . a full analysis of the effect on parameter estimation has not yet been carried out . it was demonstrated by carter that the kerr metric has a complete set of integrals in addition to the energy and angular momentum that arise as conserved quantities in any stationary and axisymmetric spacetime , geodesics in the kerr metric conserve the carter constant , q. this is the analog of the third isolating integral found in some classical axisymmetric systems , and has been shown to arise due to the existence of a killing tensor of the spacetime . in the schwarzschild limit , q is the sum of the squared angular momentum components in the two equatorial directions . the kerr metric is one of a very special class of metrics that have this property . in fact , carter demonstrated that it was the only axisymmetric metric not containing a gravitomagnetic monopole for which both the hamilton - jacobi and schrdinger equations were separable . the special nature of the kerr metric was emphasized by will who demonstrated that , in newtonian gravity , motion about a body with an arbitrary set of multipole moments ml possesses a third integral of the motion only if the multipole moments obey the conditions 62 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { m _ { 2l + 1 } } = 0 , \\ quad \\ , \\ , { m _ { 2l } } = m { ( { m_2 } / m ) ^ l } \\ quad { \\ rm { for } } \\ , { \\ rm { every } } \\ , l , $ $ \\ end { document } which are precisely the conditions satisfied by the mass moments of a kerr black hole , eq . the separability of the kerr metric aids the analysis of inspirals in that spacetime , but it also suggests another potential observable that would show a deviation from the kerr metric in a gw observation . the specialness of the third integral in the kerr spacetime suggests that if a spacetime differed from the kerr solution , even by a small amount , the third integral might vanish , which would potentially lead to the existence of chaotic orbits . if such orbits were observed it would be a clear smoking gun for a deviation from the kerr metric . the standard approach is via construction of a poincar map : a geodesic is computed in cylindrical coordinates ( , z , , ) , and the values of and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ dot \\ rho } $ \\ end { document } recorded every time the particle intersects a specified plane z = constant . if the resulting plot of all these points on a ( , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ dot \\ rho } $ \\ end { document } ) plane yields a closed curve , then a third integral exists , otherwise the orbit is chaoticfigure 7poincar map for a regular orbit ( left panel ) and a chaotic orbit ( right panel ) in the manko - novikov spacetime . image reproduced by permission from , copyright by aps . poincar map for a regular orbit ( left panel ) and a chaotic orbit ( right panel ) in the manko - novikov spacetime . chaotic motion has been found by sota et al . for orbits in the zipoy - voorhees - weyl and curzon spacetimes ; by letelier and viera for orbits around a schwarzschild black hole perturbed by gws ; by gueron and letelier for orbits in a black - hole spacetime with a dipolar halo , and in prolate erez - rosen bumpy spacetimes ; and by dubeibe et al . for some oblate spacetimes that are deformed generalizations of the tomimatsu - sato spacetimethe only investigation to date of chaotic orbits in the context of lisa was by gair et al . , who explored geodesic motion in a family of spacetimes due to manko and novikov that had arbitrary multipole moments , but which included kerr as a special case . considered orbits in a family of spacetimes parameterized by a single excess quadrupole momentthey found that , while the majority of orbits in these spacetimes possessed an apparent third integral , chaotic orbits existed very close to the central object for arbitrarily small oblate deformations of the kerr solution . as the spacetime was deformed away from kerr , a second allowed region for bound geodesic motion was found to appear close to the central black hole , in addition to the allowed region present in the kerr metric . concluded that this chaotic region would probably be inaccessible to an object that was initially captured at a large distance from the central object . this analysis was revisited in but the conclusions in that paper were the same . the only difference was that the authors in identified a region of stable motion within the inner region that contains chaotic orbits . the chaotic orbit shown in the right hand panel of figure 7 appears to pass in and out of the region of stability which should not happen , so this might be a numerical artifact . however , the existence of chaotic orbits and the probable inaccessibility of these orbits to inspirals was confirmed by . brink also explored integrability in arbitrary stationary , axisymmetric and vacuum spacetimes , concentrating on regions where the poincar maps indicated the presence of an effective third integral . brink hypothesized that some spacetimes might admit an integral of the motion that was quartic in the momentum , in contrast to the carter constant , which is quadratic . the kolmogorov , arnold , and moser ( kam ) theorem indicates that when a hamiltonian system with a complete set of integrals is weakly perturbed , the phase - space motion will either be confined to the neighborhoods of the invariant tori , or the motion will be chaotic . thus , if there is a region of the spacetime where chaotic motion exists , there can not be another region where a third invariant exists . a mathematical demonstration that the orbits can possess an approximate invariant , while technically being chaotic , is lacking at present , small everywhere , since the change in mutipole moments necessarily changes the horizon structure and so the perturbation is infinitely large at certain points . a discussion of the reason for the existence of chaotic geodesics in some spacetimes was given by sota et al . . they suggested that it would arise either from a change in sign of the eigenvalues of the weyl tensor at a point , which would lead to a local instability , or from the existence of homoclinic orbits . the latter explanation applied only to non - reflection - symmetric spacetimes , while most spacetimes of astrophysical interest should be reflection symmetric . the weyl - tensor analysis has not been carried out for the manko - novikov family of spacetimes . one other proposed explanation was the existence of a region of closed timelike curves , which was found to touch the region in which chaotic motion was identified . in conclusion , it seems unlikely that chaotic geodesics will be found in nature , but if they were identified we would know immediately that the spacetime was not kerr . one possibility would be to observe the transition from regular to chaotic motion in a time - frequency analysis : the regular motion would be characterized by a few well - distinguished peaks in a fourier transform of the signal , while chaotic motion would show a much broader band structure . however , it is not clear that it would be possible to distinguish the chaotic phase from detector noise , and hence there would be no way to identify an inspiral that ends by entering a chaotic phase as opposed to one which ends at plunge into a black hole . if an orbit passed into a chaotic phase and then back into a regular phase we might see a signal turn on and off repeatedly . however , the chaotic motion would randomize the phase at the start of the regular motion , so to detect such a signal we would need each regular phase to be long enough that they were individually resolvable by matched filtering . eccentric and inclined emris will generically pass through transient resonances at which the radial and frequencies become commensurate . for emris in gr , these resonances will be isolated , and the transition through resonance will proceed on the usual radiation - reaction timescale but with a temporary modification in the energy flux on resonance . however , according to the poincar - birkhoff theorem , when an integrable system is perturbed it causes the appearance of a birkhoff chain of islands whenever the frequencies of the system are at resonance . therefore , in a perturbed kerr spacetime , another observable consequence would be that the emri frequencies could remain on resonance for many more cycles , providing another smoking gun for a deviation from kerr . detection of a persistent resonance in a matched - filtering search will require a modification of the search pipeline , but it should be considerably more straightforward than detection of chaos , as the signal will be coherent and could therefore be identified using time - frequency methods , or a phenomenological waveform model . as mentioned in section 5.1.3 , in massive scalar - tensor theories , a different type of persistent resonance can occur , in which a super - radiant scalar flux balances the gw flux . such resonances can last a significant fraction of a hubble time and so observing a single emri offers significant constraining power on the space of massive scalar - tensor theories . this is not a test of black - hole structure , since the resonance is between the scalar and gravitational fluxes , rather than in the geodesics of the central object , but the observable effects are similar so we mention it here . the ryan mapping approach uses observations of precession frequencies as functions of the orbital frequency to extract the spacetime metric from gws . however , even if the metric is found to be kerr , this is not enough to verify gr . it was pointed out by psaltis et al . that the kerr metric is a solution to the field equations for several alternative theories of gravity . essentially , since the kerr metric has vanishing ricci tensor , r = 0 , any theory in which the vacuum field equations depend only on r will also admit kerr as a solution . allowing for a nonzero cosmological constant , a , a black - hole solution in gr satisfies 63 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { r _ { \\ mu \\ nu } } = { r \\ over 4 } { g _ { \\ mu \\ nu } } , \\ quad r = 4 \\ lambda , \\ quad { \\ rm { and } } \\ quad { r _ { ; \\ mu } } = 0 , $ $ \\ end { document } in which r denotes the ricci scalar and is the spacetime metric . discussed four different alternative theories , already described in section 2.1 f ( r ) gravity in the metric formalism . if f ( r ) is expanded as a taylor series a0 + r + a2r + , there are three possible cases . ( i ) if a0 = 0 the kerr solution , which corresponds to r = 0 , is always a solution to the equations of motion . ( ii ) if the taylor series terminates at a2 , all constant curvature solutions of gr ( with any ) remain exact solutions of the f ( r ) theory . ( iii ) if a00 and the series does not terminate at a2 , constant - curvature solutions of gr will be solutions of the f ( r ) theory with different values of the curvature . the difference in curvature will be small , however.f ( r ) gravity in the palatini formalism . in this case , any constant - curvature solution of gr is also a solution to these equations , with the same christoffel symbols . this is unsurprising , as it is known that palatini f ( r ) gravity reduces to gr in vacuum . general quadratic gravity . for any black - hole solution in gr , the tensors and that appear in the field equations ( 18 ) both vanish , and the field equations reduce to those of gr . hence all black - hole solutions of gr are solutions in this theory.vector - tensor gravity . in this case , we find once again that all constant - curvature solutions of gr are solutions to the equations , but with a shifted value of the curvature that depends on the vector field strength r = 16 / ( 4 + ( 4 + 3 ) k ) . if f ( r ) is expanded as a taylor series a0 + r + a2r + , there are three possible cases . ( i ) if a0 = 0 the kerr solution , which corresponds to r = 0 , is always a solution to the equations of motion . ( ii ) if the taylor series terminates at a2 , all constant curvature solutions of gr ( with any ) remain exact solutions of the f ( r ) theory . ( iii ) if a00 and the series does not terminate at a2 , constant - curvature solutions of gr will be solutions of the f ( r ) theory with different values of the curvature . any constant - curvature solution of gr is also a solution to these equations , with the same christoffel symbols . this is unsurprising , as it is known that palatini f ( r ) gravity reduces to gr in vacuum . general quadratic gravity . for any black - hole solution in gr , the tensors and that appear in the field equations ( 18 ) both vanish , and the field equations reduce to those of gr . hence all black - hole solutions of gr are solutions in this theory . vector - tensor gravity . in this case , we find once again that all constant - curvature solutions of gr are solutions to the equations , but with a shifted value of the curvature that depends on the vector field strength r = 16 / ( 4 + ( 4 + 3 ) k ) . the action for general quadratic gravity introduced by stein and yunes also admits the kerr solution , but only in the non - dynamical version of the theory in which the functions are constants . in that casethe field equations are once again satisfied by spacetimes with rab = 0 , and so the vacuum solutions of gr are solutions to the field equations in these theories as well . in the dynamical version of the theory , the riemann tensor enters the field equations explicitly and so rab = 0 is no longer sufficient to satisfy them . although it is true that all of these theories admit the kerr metric as a solution , this does not mean that we have no way to distinguish between them via gw observations . this was not discussed in , but is argued in a comment on that paper by barausse and sotitirou . first , the uniqueness theorems of gr do not necessarily apply in these alternative theories . in other words , just because the kerr metric is a solution does not mean that we would expect it to form as a result of gravitational collapse . this is an equally important consideration as to what we would expect to see in the universe , although this argument can be sidestepped by suitable fine tuning . in f ( r ) gravity , the metric of a spherically - symmetric body is not the schwarzschild metric , but has a yukawa correction . the constraints that lisa could place on such a deviation from the kerr solution were investigated in . expanding f ( r ) to quadratic order ( r + a2r / 2 ) , it was found that emri observations could place a bound | a2 | 10 m , about an order of magnitude better than the bound from observations of planetary precession in the solar system , | a2 | 1.210 m. however , the bound from the et - wash laboratory experiments is many orders of magnitudes better , | a2 | 210 m . the gw constraints will be obtained in a very different curvature regime and could be of interest if something like the chameleon mechanism is invoked . the chameleon mechanism was introduced to allow f ( r ) models to explain cosmological acceleration without violating laboratory and solar - system constraints . it is a nonlinear effect that could arise when the curvature is very different from the background value , e.g. , in the vicinity of matter . if the matter density is high the scalar degree of freedom in f ( r ) gravity acquires an effective mass , which means that the effective coupling to matter becomes much smaller than the bare coupling , which is relevant on cosmological scales . therefore the bare coupling could be much higher than inferred from laboratory constraints , allowing the theories to explain cosmological acceleration ( see for a full description of the mechanism and complete references ) . in a similar way , the effective coupling in the vicinity of a compact object could in principle be different from that in the laboratory and so the weak constraints from gravitational - wave observations are still interesting because they probe a different curvature scale . subsequent to the publication of , it has been shown that the end state of gravitational collapse in f ( r ) theories ( and scalar - tensor theories ) is not the point - mass limit of an extended body , but is in fact the kerr solution . therefore the results in do not apply to black holes in f ( r ) gravity , but would apply for an exotic horizonless compact object if one existed . the constraints that low - frequency gw could place on this metric can also be considered to be constraints on a strawman yukawa - like deviation from the kerr solution , without reference to a specific theory in which such corrections arise . gws are generated by perturbations of the spacetime and hence depend on the full dynamical sector of the theory . therefore the response to perturbations will be different if the field equations are different , even if the unperturbed metric is the same . in it was demonstrated that , for metric f ( r ) gravity , linearizing about the minkowski spacetime gives rise to massive graviton modes in addition to the standard transverse - traceless modes of gr . these can not be zeroed out by a gauge transformation . to date , no one has considered the generation of such massive modes in a binary system nor the observational consequences . however , if these modes are generated , there would be two natural ways to find them : a direct gw detection ( the modes have different polarization states and propagation velocities ) , and an indirect detection , as the binary system would inspiral faster than expected due to loss of additional energy in the extra modes . it is not clear whether the latter will be distinguishable from tidal interaction effects , and quantitative estimates of the power of tests that would be possible with lisa - like detectors have not yet been done . a second example of an alternative theory in which a spacetime metric is the same as a gr solution but behaves differently perturbatively is dynamical chern - simons ( cs ) gravity . the nonrotating - black - hole solution in that theory is schwarzschild , as in gr , but it was shown in that there are 7pn and 6pn corrections respectively to the scalar and gravitational energy flux radiated to infinity by a circular emri . this could lead to a 1 - cycle difference in waveform phasing over a year of inspiral if the cs coupling parameter | | 0.1 . in post - newtonian resultswere obtained for the emission from spinning black - hole binaries in a general quadratic - gravity theory . one model within the general class considered corresponds to dynamical cs gravity and for that case the results were found to be consistent with the perturbative calculations in . in interpreting gw observations , it will be necessary to verify both the static and dynamic aspects of the theory . the ryan mapping algorithm is the natural way to start , but if a metric is found to be consistent with kerr it will then be necessary to verify that the observed gws and energy loss are also in agreement before concluding that we are observing a system consistent with a kerr black hole in gr . certain alternative theories of gravity do not admit the kerr metric as a solution : these include the dynamical version of general quadratic gravity described by eq . it is difficult to solve the field equations in alternative theories , so few analytic black - hole solutions are known outside of gr . solutions for slow rotation are known in dynamical cs gravity , which is a special case of eq . ( 19 ) with 1 = 2 = 3 = 0 , to leading order in spin and now to quadratic order . slow - rotation solutions are also known in einstein - dilaton - gauss - bonnet ( edgb ) gravity , in which gravity is coupled to dilaton and axion fields . in the weak - coupling limit , spherically symmetric and stationary solutions to the general quadratic - gravity theory described by eq . ( 19 ) take the same form as the solutions to edgb gravity and were derived in . solutions to this same class of theories are also known for arbitrary coupling , but only under the slow rotation approximation , and these were given in . in dynamical cs gravity , it was shown that the metric describing a slowly rotating black hole at linear order in the spin differs from the slow - rotation limit of the kerr metric beginning at the fourth multipole , l = 4 . it was also shown that the equations describing perturbations of this metric in dynamical cs gravity coincide with those of gr at leading order in spin and coupling parameter , with corrections due to the sourcing of metric perturbations by the scalar field entering at higher order . therefore it was argued that the deviations from gr will manifest themselves primarily through differences in the geodesic orbits in the spacetime . therefore this is completely analogous to spacetime mapping within gr , as described in section 6.2.1 , so the prospects for detection of such deviations with lisa - like detectors are comparable . the energy - momentum tensor of the gws was also shown to take the same form in terms of the metric perturbation as it does in gr , so the leading - order correction to the gw energy flux is determined by these modifications to the conservative dynamics . energy balance also applies in this context and can be used to relate the adiabatic evolution of an orbit to the flux of energy and angular momentum at infinity . however , energy and angular momentum are also carried to infinity by the scalar field , and these corrections to the evolution were not estimated in . considering non - inspiraling geodesic orbits , sopuerta and yunes estimated that imri or emri events observed by lisa would be able to put constraints on the coupling parameter of dynamical cs gravity of \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ xi ^ { 1 \\ over 4 } } \\ lesssim { 10 ^ 2 } $ \\ end { document } km . a more complete study that included inspiral and used a fisher matrix analysis to account for parameter correlations is described in . there it was found that lisa observations of emris could place a bound \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ xi ^ { { 1 \\ over 4 } } } { 10 ^ 4 } $ \\ end { document } km . this is somewhat weaker than the bound estimated for imris in , but better than the estimate for emris in that paper , so imri systems ( involving a 10 m object inspiraling into a 10 m object ) may be able to place even more stringent constraints than originally estimated , if they were observed . the emri bound \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ xi ^ { { 1 \\ over 4 } } } { 10 ^ 4 } $ \\ end { document } km is four orders of magnitude better than the best solar - system bound , which is based on data from gravity probe b and lageos satellites . in the bound from current binary - pulsar observations was estimated to be four orders of magnitude better than that in the solar system and hence comparable to the expected gw result . however , this bound was based on an upper limit on the rate of precession . it was argued in that an upper bound could not place a constraint on the cs deviation since the sign of the cs contribution is opposite to that in gr , and so a bound could only be placed if a lower bound on the precession lying below the gr value could be found . therefore the solar - system bound is the best current constraint , which gw observations will improve by several orders of magnitude . the chern - simons black - hole metric has recently been derived to quadratic order in the spin , so the results discussed here can now be extended to this higher - order metric . this second - order solution had several interesting properties , in particular the petrov type7 is type i , whereas it was type d in the linear - spin case ; furthermore , there is no second - order killing tensor , which means orbits do not have a third carter - constant - like integral of the motion . this could have important observable consequences for gws from emris , as discussed in section 6.2.5 . the analogous calculation to , the evolution of an emri in the strong - field region of the metric , has not yet been carried out for the second - order cs metric . however , the gw emission from quasi - circular binaries in this theory has been determined without any restriction on the spin magnitude or coupling , but in the post - newtonian limit , i.e. , with a restriction on the magnitude of the velocity . this waveform model was constructed using energy balance and expressions for the gravitational - wave energy flux emitted in general quadratic - gravity theories that were derived in . these were given in section 5.1.3 and are two orders of magnitude better than the emri constraints estimated using the linear - spin metric . these constraints were derived in a very different mass - ratio regime ( a binary with mass ratio of 1:2 ) , but the fact that they are so much better is probably not surprising since the quadratic in spin corrections to the metric enter at a lower post - newtonian order than the linear - spin corrections . therefore it is likely that the bounds that emris could place on cs gravity are much stronger than quoted here . this possibility and possible qualitative signatures of the loss of the third integral in the higher - order cs metrics should be further investigated . in the small - coupling limit , it can be shown that the energy - momentum tensor of gws in the general quadratic - gravity theory [ eq . ( 19 ) ] also follows the same quadrupole formula as in gr . using this result , a post - newtonian expression for the energy flux emitted from a quasi - circular binary in these theoriescorrections to the energy flux come from changes to the conservative dynamics , i.e. , to the orbits that test particles follow in the background metric , from energy lost in scalar field radiation and from the contribution to the gw energy - momentum integral from metric perturbations sourced by the scalar field . the authors found that , for these theories , the scalar dipole radiation dominates the correction to the energy flux and enters at a post - newtonian order ofi.e . , at a power of v / c one order before the gw energy flux of gr . there are also 0pn and 2pn corrections to the flux from the scalar - metric interaction and the modification to the conservative dynamics . the observability of these waveform differences with space - based gravitational detectors has , so far , only been directly estimated for the specific case of einstein - dilaton - gauss - bonnet gravity . in that case , the constraints derivable with space - based gw detectors were compared to those that can be obtained from observations of low - mass x - ray binaries . some of these are observed to have orbital decay rates that are larger than predicted by radiation reaction in gr . assuming this excess orbital - decay rate arises from additional scalar radiation emitted from the binary , it is possible to obtain a bound six times stronger than that derivable from solar - system experiments ( using the binary a0620 - 00 ) of \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ sqrt { | \\ alpha | } 1.9 \\ times { 10 ^ 5 } $ \\ end { document } cm . elisa would be able to place a bound that is slightly stronger ( a factor of two ) than this , while combining multiple decigo observations would yield a bound three orders of magnitude better . for other theories in this general quadratic class , however , the post - einsteinian parameters have been calculated for circular - equatorial inspirals in this class of theories . the parameters characterizing the modification to the gr waveform in the ppe framework are defined through the expression 64 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ tilde h = { \\ vert } { \\ tilde h _ { { \\ rm { gr } } } } { \\ vert } ( 1 + \\ alpha { \\ eta ^ c } { u ^ a } ) \\ exp [ { \\ rm { i } } \\ psi _ { { \\ rm { gw } } } ^ { { \\ rm { gr } } } ( 1 + \\ beta { \\ eta ^ d } { u ^ d } ) ] , $ $ \\ end { document } in which = m1m2 / ( m1 + m2 ) is the mass ratio of a binary with component masses m1 and m2 , u = f , = ( m1 + m2 ) is the chirp mass and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ tilde h } _ { { \\ rm { gw } } } } / \\ psi _ { { \\ rm { gw } } } ^ { { \\ rm { gr } } } $ \\ end { document } are the general - relativistic waveform and waveform phase respectively . under the weak - coupling approximation , the metric of non - spinning black holes in these general quadratic - gravity theories depends only on a parameter \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ varsigma \\ propto \\ alpha _ 3 ^ 2 $ \\ end { document } . for mergers of such black holes , the ppe parameters were found to be = ( 5/6 ) , = ( 50/3 ) , a = 4/3 = b , c = 4/5 = d . more recently , the ppe corrections to the waveform phase ( which are parametrized by b and ) were found without making a weak - coupling approximation and for binaries with spinning components . the exponent depends on whether the black holes are spinning and on which coefficients of the theory are allowed to be non - zero . the authors considered the cases of odd parity ( i.e. , including the pontryagin term 40 ) and even parity ( i.e. , including the other terms quadratic in the curvature , 1 , 2 , 3 = 0 ) separately . the exponent of the ppe phase correction was found to be b = 7/3 for spinning black holes in even - parity theories , b = 1/3 for spinning black holes in odd - parity theories , and b = 3 for non - spinning black holes . the authors also obtained equations , which we do not present here , relating the ppe amplitude , , to the coupling constants of the theory . if a gw observation is used to place bounds on these ppe parameters , these expressions can be used to translate the bound into a constraint on this set of alternative theories of gravity . as discussed in section 5.2.2 , the authors of considered more general possible forms for black - hole solutions without specifying a particular alternative theory . by imposing the existence of a carter - like third integral of the motion , asymptotic flatness , and the peeling theorem8 , and by settingas many metric components to zero as possible while still recovering all known modified gravity spacetime metrics , they obtained a family of generic modified black - hole solutions . it was subsequently realized that all solutions admitting a carter constant had been found in , but identifies the physically - realistic subset of these general solutions . this approach is suited to the construction of eccentric , inclined inspirals , and in the gws for generic emris occurring in these metrics were constructed by extending the analytic - kludge framework . asyet , these waveforms have not been used to assess the ability of a space - based detector to constrain such deviations from the kerr solution , but work in this area is ongoing . the previous sections 6.2.16.2.6 have identified some of the possible causes of deviations in the structure of the central object from the kerr metric , as well as some observational consequences of these deviations . nevertheless , interpreting gw observations correctly is a nontrivial challenge . our working assumption is that the massive compact objects that occupy the centers of most galaxies are indeed kerr black holes . therefore it is reasonable to design an approach to spacetime mapping that looks for inspirals into kerr black holes and quantifies any deviations from such inspirals that may be present . the starting point is to assume that gr is correct , and that the source s spacetime is vacuum and axisymmetric . the multipole moments can be extracted from the precession frequencies via ryan s algorithm , and then the expected gw and inspiral rate for such a spacetime in gr can be computed . if the observations are consistent there is no evidence to contradict the initial assumptions , but we can still do several tests , by asking the following questions : ( i ) does the no - hairif there is a deviation , the spacetime must either contain closed - timelike curves , or lack a horizon . ( ii ) does the emission cut off at plunge or does the radiation persist ? ( iii ) is the tidal interaction consistent with a kerr black hole ? if the radiation still cuts off at a plunge and the multipole structure is not consistent with the kerr metric , it might indicate the presence of a naked singularity , which would be a violation of the cosmic - censorship hypothesis . if the observations are not consistent with gr , the first assumption to relax would be that the spacetime was vacuum . in principle , it might then be possible to deduce both the multipole moments of the spacetime and the energy - momentum tensor of the matter distribution from the observations . the gw could then be computed for such a spacetime in gr , and checked for consistency with the observations . if the observations are consistent , similar questions can be asked : ( i ) does the emission cut off at plunge or does the radiation persist ? ( iii ) does the matter distribution obey the strong , null , and weak energy conditions , or have we identified an exotic matter distribution ? only if the observations are inconsistent will there be evidence of a failure in gr itself . the main complication to this approach is that the detection of emris will rely on matched filtering using waveform templates . if a system differs significantly from a kerr inspiral , then it may not be picked out of the data stream . she suggested that the spacetime - mapping problem could be thought of as analogous to inversescattering problems in quantum mechanics , where the potential to be determined is the ernst potential ( see discussion in section 6.2.1 ) , but the technical details of such a method have not yet been worked out . brink also suggested an approach with a similar philosophy to what we discuss above : assuming that the instantaneous geodesic is triperiodic ( i.e. , that it has a complete set of integrals ) , there is a good chance it will have a high overlap with a kerr geodesic . the inspiral defines a point in the kerr geodesic space , and so matched filtering with kerr snapshots can pick out an inspiral trajectory . the inspiral trajectory in the kerr spacetime can be computed , and we can check to see if the observed inspiral deviates from the predicted one . this approach has two drawbacks : first , it relies on the gws from a geodesic in an arbitrary spacetime having a high overlap with those from at least one kerr geodesic ; second , the interpretation of deviations in the trajectory relies on being able to compute gw emission in alternative metrics in gr , or in alternative theories of gravity . one approach to addressing the first of these problems is to search for emris using a template - free approach . one method would be to search for tracks of excess power in the time - frequency domain . however , excess - power algorithms lose information on the phase of the waveform , which is the most important observable for carrying out tests of gr . more recently , a method that attempts to match the phase of individual harmonics using a taylor expansion with a small number of coefficients was described in , which built on ideas used to search for gr emris in the mock lisa data challenges . while the method appears promising , it must be kept in mind that so far these approaches have only been used on highly simplified datasets containing a single emri source . issues related to confusion between the harmonics of the multiple sources expected in real data have not yet been properly explored . , it is clear that low - frequency gw detectors will be able to check that an emri is consistent with kerr , which can be interpreted as a statement on how much the spacetime could differ from the kerr metric and still be consistent with our search templates . what is more difficult is to say exactly what lisa will tell us if we observe something that does differ from the kerr metric . more work is still needed in this area . another class of low - frequency gw sources that are closely connected to emris are extreme - mass - ratio bursts emrbs . these are the precursors to emris : in the standard emri formation channel , compact objects are perturbed onto orbits that pass very close to the central black hole , emitting bursts of gws as they do , which can lead to capture if sufficient orbital energy and angular momentum are lost to gws . furthermore , just after capture , emri compact objects proceed on very eccentric orbits that radiate in bursts near pericenter rather than continuously . emris objects that only encounter the central black hole a few times before being perturbed onto an unbound or plunging orbit . for a sufficiently nearby system ( in the virgo cluster or closer ) , these bursts could be individually detected by lisa - like detectors . the low snr of such events compared to emris is partially outweighed by the significantly larger number of compact objects undergoing flybys at a given time , so the detection rate could be as high as 18 yr , of which 15 yr would originate in the milky way . a more careful analysis predicted only 1 event per year , and a proper analysis of our ability to identify such bursts in the presence of signal confusion has not been carried out . therefore it is unclear at present whether any of these events would be identified in the data of lisa - like detectors . it has been suggested that emrbs could be used to test black - hole structure in a similar way to emris . this assertion was based on comparing approximate burst waveforms coming from spinning and nonspinning central black holes with the same system parameters . in , an analysis of parameter estimation for emrbs accounting for parameter correlations was performed , which concluded that a space - based detector like lisa could measure many of the parameters of the system to moderate precision , including the mass and spin , provided that the periapse of the burst orbit was within 10 gm / c . this analysis did not consider sky position or eccentricity to be free parameters , taking the former to be the center of the milky way , and the latter to be maximal , and it treated the distance and compact - object mass as a single amplitude parameter m / d . the small object mass can not be separately determined because there is no significant orbital evolution over the duration of one burst . the analysis did not consider constraints on gr through measurements of other multipoles , but it was found that the mass and spin could both be measured to high accuracy for orbits that pass sufficiently close to the black hole . therefore it may also be possible to place some kind of constraint on gr deviations using these systems . however , the event rate for such relativistic systems is very low so we will have to be lucky to see a useful event . useful burst events might also be seen from nearby galaxies other than our own , which are thought to have black holes in the appropriate mass range . other unknown black holes in the local universe could also provide sources , but for such extra - galactic systems , the sky position will be unknown and so a single burst will not provide enough information to allow the determination of all the system parameters . if an emrb was observed to repeat several times over the lifetime of a gw mission , then more information could be derived about the system . however , there are serious practical issues with associating multiple , well - separated bursts with the same source . the inspiral orbit might also be perturbed between pericenter passages by encounters with other stars . the prospects for doing useful tests of black - hole structure with emrbs therefore seem rather bleak . moreover , any tests that can be carried out will inevitably be much weaker than those based on emris , as an emrb event will generate several waveform cycles rather than the several hundred thousand from an emri . when a black hole is perturbed , it rapidly settles back down to a stationary kerr state via the radiation of exponentially damped sinusoidal gws known as quasi - normal modes ( qnms ) . for a kerr black hole in gw , the qnm frequencies and damping times are uniquely determined by the mass and spin of the black hole . observations of two or more qnms from the same system will therefore test that the end - state of the merger is a kerr black hole , if they provide consistent estimates for the mass and spin of the central object . qnms will be excited during the merger of supermassive black holes and will dominate the late - stage radiation , so lisa - like detectors should observe qnm radiation with relatively high snrs . in fact , the snr from the qnms alone may be comparable to the total snr in the inspiral . this is illustrated in figure 8 , which shows the snr with which lisa would detect the inspiral and ringdown for equal - mass , nonspinning mbh binaries as a function of black - hole mass . the ringdown dominates the snr for redshifted masses greater than 310 m. figure 8comparative snrs , as a function of redshifted black - hole mass ( 1 + z ) m , for the last year of inspiral of an equal - mass mbh binary and for the ringdown after the merger of the system . the method used to generate this figure follows that of , updated to use a modern lisa sensitivity curve with a low - frequency cutoff of f = 110 hz . the redshift is set to z = 1 , at which the luminosity distance is dl = 6.6 gpc using wmap 7 - year parameters . comparative snrs , as a function of redshifted black - hole mass ( 1 + z ) m , for the last year of inspiral of an equal - mass mbh binary and for the ringdown after the merger of the system . the method used to generate this figure follows that of , updated to use a modern lisa sensitivity curve with a low - frequency cutoff of f = 110 hz . the redshift is set to z = 1 , at which the luminosity distance is dl = 6.6 gpc using wmap 7 - year parameters . reviews of the theory of quasi - normal modes can be found in kokkotas and schmidt , in nollert and in berti , cardoso and starinets , but we will briefly summarize the relevant results here . at late times , the gravitational radiation from a perturbed black hole can be written as a sum of exponentially - damped sinusoids . it is known that qnms do not form a complete set in a mathematical sense , but numerical results confirm that the late - time behavior is well described by such an expansion . the angular dependence can be decomposed into a sum of spheroidal harmonics of spin weight 2 , which are labeled in analogy to standard spherical harmonics . for each ( l , m ) , there are infinitely many resonant qnms , which can be labeled in order of decreasing damping time by a third parameter n. the waveform expansion takes the form 65 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { h _ + } + { \\ rm { i } } { h _ \\ times } = { m \\ over r } \\ sum \\ limits _ { lmn } { { { \\ mathcal a } _ { lmn } } { { \\ rm { e } } ^ { { \\ rm { i } } ( { \\ omega _ { lmn } } t + { \\ phi _ { lmn } } ) } } { { \\ rm { e } } ^ { - t / { \\ tau _ { lmn } } } } { s _ { lmn } } } , $ $ \\ end { document } where lmn , lmn , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ mathcal a } _ { lmn } } $ \\ end { document } , and lmn are the frequency , damping time , amplitude , and initial phase of the mode , and slmn is a complex number obtained by evaluating the spheroidal harmonics for the particular orientation and mode frequency . the frequency and damping time , lmn and lmn , are determined solely by the mass and frequency of the central black hole and are the key observables . the damping time can also be considered as the reciprocal of the imaginary part of a complex mode frequency , the amplitude and phase depend on the exact nature of the perturbation that excited the qnms , so they are less useful . one complication is that the mode numbers that are excited [ i.e. , the ( l , m , n ) parameters ] are not known a priori . in the first analysis of snr from qnms , it was assumed that only the l = m = 2 , n = 0 was excited , which simplifies analysis of the observations . however , this simplifying assumption is not needed in general . the use of qnms as a probe of black - hole structure was first proposed by dreyer et al . , who coined the phrase black - hole spectroscopy for this technique . a measurement of lmn and lmn for a single qnm will give several discrete solutions for the black - hole mass and spin , corresponding to different choices for the mode numbers . a measurement of a second qnm will give another discrete set of values , and in general these will not be the same as the first set except for one combination , which are the true values . this not only determines the black - hole parameters , but provides a test that the central object is a kerr black hole , since the relationship between black - hole parameters and frequencies depends on that assumption . if the object was something else , we would find no consistent combination of mass and spin parameters to arise from the analysis . we denote a set of choices for the n modes to which the frequencies correspond by \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ mathcal q } $ \\ end { document } . each \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ mathcal q } $ \\ end { document } defines a two - dimensional curve in the 2n + 2 dimensional space , parameterized by ( a , m ) . the probability distribution for the observed frequencies , , may be denoted by \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ p ( \\ omega | a , \\ , m , \\ , { \\ mathcal q } ) $ \\ end { document } and can be used to define a confidence interval by determining the p0 such that 66 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ int \\ nolimits _ { \\ { \\ omega : p ( \\ omega { \\ vert } a , m , { \\ mathcal q } ) { p_0 } \\ } } \\ , \\ , p ( \\ omega { \\ vert } a , m , { \\ mathcal q } ) { \\ rm { d } } { \\ omega ^ { 2n } } . $ $ \\ end { document } dreyer et al . deemed that an observation was inconsistent with gr if the actual observed frequencies lay outside such confidence intervals for all possible choices of a , m and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { \\ mathcal q } $ \\ end { document } . using a toy model for a non - black - hole source , and assuming that two qnms were observed , drawn from four possible excited modes , they estimated that , with a false alarm probability of 1 % , the false dismissal rate would be 60 % if the snr in the weakest mode was 10 , falling to 10 % at an snr of 100 . assuming a reasonable amount of energy deposition into the qnms , they estimated that this would be satisfied by all lisa mbh merger sources , so the prospects for such tests are good . they computed snrs that improved on those in by using an up - to - date detector noise curve and including black - hole spin . for a source of mass 10 m m 10 m at a distance of 3 gpc , they found snrs between 10 and 210 for an excitation energy of 3 % of the rest mass , and between 1 and 3000 for an excitation energy of 0.1 % . there is little dependence of the snr on the central black - hole spin . putting the source at higher z shifts the sensitive range of masses in the usual way , but even at redshift z = 10 the maximum snr was found to be several hundred . . also looked at parameter - estimation accuracy from observations of one qnm ( with known mode numbers ) and found that lisa observations would measure the mass and spin to fractional accuracies in the range 1010 for sources at d = 3 gpc and for the masses as quoted above . also performed a fisher - matrix analysis of a two - mode problem , which accounted for all correlations between the modes . pseudo - orthonormal modes with different angular dependence ( l l or m m ) and overtones that is , modes with the same angular dependence ( l = l and m = m ) . in both cases , the accuracy of determination of the mass and spin was comparable to the results quoted for a single mode , although the parameter space was simplified significantly to just five parameters : a , m , two mode amplitudes \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ { { \\ mathcal a } _ 1 } , \\ , { { \\ mathcal a } _ 2 } $ \\ end { document } and a common initial phase . berti et al . define two distinct qnms to have resolvable frequencies if the difference in these is larger than the error in both ( and similarly for the damping times ) . by recasting the two - mode model in terms of the two mode frequencies and damping times rather than a and mconsidered two cases ( the resolvability of either frequencies or damping times , and the resolvability of both ) , and they computed the source snr needed in each case . when the two modes are overtones , the snr required to resolve either was 100 , the exact value depending on the black - hole spin and the ( l , m ) numbers of the mode , but the snr required to resolve both was 1000 . when the two modes are pseudo - orthonormal , the snr range to resolve either is a few if the modes differ in l , and a few tens if the modes have the same l but differ in m and the central black - hole spin is a 0.4 . there is a mode degeneracy , which means the snr required blows up when l = l and a 0 . the snrs required to resolve both modes are in the range 10010000 . conclude that even under pessimistic assumptions about the amount of energy radiated in ringdown radiation , it should be possible to resolve one qnm and either the damping time or frequency of a second qnm , provided that the first overtone radiates 10 of the total ringdown energy . this will provide enough for a test of the no - hair property of the central object . a stronger test would come from detecting frequencies and damping times for both qnms , but this would require ringdown snrs 1000 , which is rather unlikely . the main uncertainty in this analysis was in the excitation coefficients for the various modes , but numerical relativity simulations have now provided some information on the excitation of ringdown modes in a merger . this paper revised downward the snr required to detect either the frequency or damping time of a second mode , which is sufficient for a test of the no - hair theorem , to crit 30 for any binary with mass ratio greater than 1.25 . a significant fraction of lisa events should satisfy this criterion ( see for example ) . in , the authors used numerical - relativity simulations of nonspinning black - hole binaries , with a variety of mass - ratios ranging from 1:1 to 1:11 , to compute the amplitude to which several different ringdown modes were excited , and hence an estimate of the snr with which lisa would be able to observe them . for all the mass ratios considered , the ( 3 , 3 ) mode was found to radiate between 2 % and 20 % of the energy of the ( 2 , 2 ) mode , and for mass ratios more unequal than 1:2 the ( 4 , 4 ) also radiated more than 1 % of the energy of the ( 2 , 2 ) mode . for sources at a redshift of z = 1 , they estimated a total ringdown snr between 1000 and 20000 for black - hole masses in the range 1010 m and mass ratios from 1:1 to 1:25 , with individual snrs in the ( 2 , 2 ) , ( 2,1 ) , and ( 3 , 3 ) modes between several hundred and 10000 . the mode snrs do not add in quadrature , but these snrs more than meet the requirements of for lisa to be able to carry out black - hole spectroscopy . the snrs realizable with elisa will be a few factors lower and the systems will tend to have lower masses , for which the intrinsic snrs are also smaller . therefore constraints from elisa will be weaker and it is possible that elisa will not be able to resolve sufficient separate modes , but this has not yet been explored . in , gossan et al . applied the results of to explore the practicality of using qnm radiation to test relativity . the authors considered mergers with mass ratios of 1:2 and constructed a waveform model comprised of four ringdown modes . they used bayesian methods and approached the problem of testing relativity in two ways : ( i ) determining the parameters of each ringdown mode separately and checking for consistency ; ( ii ) comparing the bayesian evidence of the gr model to a non - gr model constructed by allowing for deviations of the mode parameters from the gr predictions . the analysis was carried out for elisa and for the einstein telescope , the proposed third - generation ground - based detector . showed that method ( i ) could reveal inconsistencies of 1 % in the qnm frequency for events of mass 10 m at a distance of 50 gpc and inconsistencies of 10 % for systems of mass 10 m at 6 gpc . better constraints will come from systems at smaller distances and will therefore be observed with higher snr . using method ( ii ) , in the case of a signal from a 10 m black hole , 2 % , 6 % , and 10 % deviations in the frequency of the dominant mode would be identifiable at distances of approximately 1 gpc , 5 gpc , and 8 gpc , respectively . deviations of 2 % , 6 % and 10 % in the damping time of the dominant mode would only be detectable at distances of 200 mpc , 700 mpc , and 1.2 gpc , respectively . for a more massive system , of 10 m , a 2 % deviation in the frequency / damping time of the dominant mode would be detectable out to 35/25 gpc , but deviations of 5 % or more would be detectable at greater than 50 gpc . such massive systems are very rare , however , and the choice of a 1:2 mass ratio means that the qnm radiation is stronger than would be expected for typical elisa events , which are likely to have larger mass ratios . therefore this study was limited in extent , but these preliminary results suggest that qnms could place interesting constraints on gr modifications for the strongest signals detected by elisa . space - based qnm observations could be used directly to put constraints on alternative theories of gravity , but this will require a calculation of the qnms in those alternative theories . it was shown in that the equations governing black - hole perturbations in dynamical cs gravity were different from those in gr , with the consequence that the qnm spectrum would also be different . the authors did not compute qnms , but qnm frequencies for non - spinning black holes in dynamical cs gravity were computed in . the qnm spectrum was found to be different , due to the coupling of the black hole oscillations to the scalar field , but the detectability of these deviations by a gravitational - wave detector was not estimated . therefore , it is not yet clear at what level ringdown radiation will be able to constrain the cs coupling parameter . if a lisa - like observatory observes a mbh inspiral and does not detect qnm ringing from the merger remnant where radiation would be expected , this might indicate a violation of the cosmic - censorship hypothesis . qnm ringing arises as a result of gws becoming trapped near the horizon of the black hole . if a horizon was absent , for instanceif a super - extremal ( a / m 1 ) kerr metric was formed , we would not expect to observe the qnm radiation . this would be evidence for the existence of a naked singularity , and a counterexample to cosmic censorship , although not an indication of a problem with gr . although there are still many open questions , current research clearly indicates that low - frequency gw detectors will be able to make strong statements about the structure of the massive compact objects in the centers of galaxies by observing emris and by detecting ringdown radiation following supermassive black - hole mergers . at the very least , it will be possible to test that an observation is consistent with an inspiral into a kerr black hole , and to state quantitatively how so large a deviation from kerr could have been masked by instrumental noise . if a system differed significantly from kerr , we would identify the deviation and should be able to quantify its nature . how well we would be able to distinguish between different types of deviation ( e.g. , external matter vs. a different multipole structure of the central object ) is still not totally clear , but there are ongoing efforts in this direction . the tests of black - hole structure outlined in this section will rely on the detection of small differences between the observed gws and the gws expected in gr . these waveforms can be computed using black - hole perturbation theory , by evaluating the gravitational self - force , but despite extensive work in this area the calculation of the self - force is not yet complete even at first order in the mass ratio . the first - order gravitational self - force has been computed for circular and generic orbits in the schwarzschild spacetime and the scalar self - force is known for circular equatorial orbits in the kerr spacetime . recently , the first self - force - driven inspirals have been computed , under an adiabatic approximation for the gravitational self - force , and self - consistently for the scalar self - force .9 emri models will require knowledge of the gravitational self - force for generic orbits in kerr , which is still not available at first order . it has also been recognized that the radiative part of the second - order self - force will also be required to derive emri waveform phase to sufficient accuracy . a formalism for the evaluation of the second - order self - force has been developed , but not yet implemented . complete reviews of the current status of the self - force program can be found in . additional complications in emri modeling arise from the need to accurately follow the transition of the inspiral through transient resonances . although many of these issues will have been resolved by the time data from a space - based gravitational - wave interferometer is available , they must be borne in mind in the interpretation of future results on tests of gr . low - frequency gw detectors will provide information on black - hole structure to a much higher precision than can be achieved by other techniques . it has been suggested that observations of imris with advanced ligo will have some power to do similar tests . this data will be available ten or more years prior to any space - based experiment . however , imri - based tests will be much weaker , since many fewer cycles of the gws will be detected in a single observation due to the larger mass ratio ( 1010 ) ; furthermore , event rates are highly uncertain and accurate modeling of imris is far behind emri modeling . an imri observation would be able to detect a deviation from kerr of fractional order unity in the quadrupole moment of a source , compared to the 10 fractional accuracies achievable with lisa emris . psaltis provides a thorough review of tests of strong - field gravity using electromagnetic observations . x - ray interferometers ( e.g. , the black hole imager ) will soon have the angular resolution to directly image the horizon of extragalactic black holes at distances of 1 mpc . the accretion flow for the milky way black hole , sgr a * , can already be imaged directly down to its innermost edge . however , interpretation of the observations is complicated by the need to simultaneously constrain the disc properties . observations at multiple wavelengths will be required to fit out the disc and directly image the shadow of the black hole on the disc.evidence for the existence of horizons also comes from observations of quiescent x - ray binaries . an x - ray binary typically comprises a star filling its roche lobe and transferring matter to a compact - object companion . that compact object can either be a neutron star or a black hole . if the object is a neutron star then most of the gravitational potential energy of the accreting matter has to be radiated away , but for black holes a significant amount of this energy can be advected through the black - hole horizon and is therefore not radiated to infinity . among systems in the same state of mass transfer , those containing neutron stars are expected to be systematically more luminous than those containing black holes , as has been observed in our galaxy.electromagnetic observations will really indicate the existence of a high - redshift surface in the system , and not necessarily an actual horizon . if a system contained a naked singularity with a high - redshift surface , but not a true event horizon , this would not be evident from the electromagnetic observations alone . by probing the multipole structure and verifying consistency with the no - hair theoremthe highest - temperature emission from a disc comes from the innermost stable circular orbit ( isco ) , and the flux at that temperature is proportional to the isco radius squared . if the inferred spin was found to exceed one , this might indicate failure in the black - hole model . such spin determinations have typical errors of 10 % , much greater than lisa s expected errors of 0.01 % . indirect inference of the location of the inner edge of the accretion disc could also come from the interferometric observations mentioned above in the context of horizon detection . inthe authors use radio interferometry to resolve the base of the jet in the galaxy m87 , finding it to be 5.50.4 schwarzschild radii . the jet - base radius is interpreted as being greater than or equal to the radius of the innermost edge , so this system provides evidence for prograde accretion onto a spinning black hole . observations of jets in other nearby galaxies may follow in the future , but the distance to which these structures could be resolved is quite small.accretion - disc mapping . particles in the accretion disc around a black hole move on circular geodesics of the metric . if the orbits in the disc could be mapped , this would allow spacetime mapping along the lines of ryan s theorem . two possible probes of accretion - disc structure have been identified : quasi - periodic oscillation ( qpo ) pairs and iron k lines . qpos have been used to constrain possible values of black - hole masses and spins , but there are uncertainties in the radius at which they originate , and in the resonance that gives rise to the pairs of lines . iron lines show broadening due to differential gravitational redshift and doppler shift at different points in the disc , but again their interpretation depends on unknown details of the disc geometry . in principle , the time variability of an iron line after a single flare event could constrain both the geometry and map the disc . future observations with instruments such as ixo / athena will have the time - resolution to attempt this . horizon detection . x - ray interferometers ( e.g. , the black hole imager ) will soon have the angular resolution to directly image the horizon of extragalactic black holes at distances of 1 mpc . the accretion flow for the milky way black hole , sgr a * , can already be imaged directly down to its innermost edge . however , interpretation of the observations is complicated by the need to simultaneously constrain the disc properties . observations at multiple wavelengths will be required to fit out the disc and directly image the shadow of the black hole on the disc . evidence for the existence of horizons also comes from observations of quiescent x - ray binaries . an x - ray binary typically comprises a star filling its roche lobe and transferring matter to a compact - object companion . that compact object can either be a neutron star or a black hole . if the object is a neutron star then most of the gravitational potential energy of the accreting matter has to be radiated away , but for black holes a significant amount of this energy can be advected through the black - hole horizon and is therefore not radiated to infinity . among systems in the same state of mass transfer , those containing neutron stars are expected to be systematically more luminous than those containing black holes , as has been observed in our galaxy . electromagnetic observations will really indicate the existence of a high - redshift surface in the system , and not necessarily an actual horizon . if a system contained a naked singularity with a high - redshift surface , but not a true event horizon , this would not be evident from the electromagnetic observations alone . by probing the multipole structure and verifying consistency with the no - hair theoremthe highest - temperature emission from a disc comes from the innermost stable circular orbit ( isco ) , and the flux at that temperature is proportional to the isco radius squared . if the inferred spin was found to exceed one , this might indicate failure in the black - hole model . such spin determinations have typical errors of 10 % , much greater than lisa s expected errors of 0.01 % . indirect inference of the location of the inner edge of the accretion disc could also come from the interferometric observations mentioned above in the context of horizon detection . inthe authors use radio interferometry to resolve the base of the jet in the galaxy m87 , finding it to be 5.50.4 schwarzschild radii . the jet - base radius is interpreted as being greater than or equal to the radius of the innermost edge , so this system provides evidence for prograde accretion onto a spinning black hole . observations of jets in other nearby galaxies may follow in the future , but the distance to which these structures could be resolved is quite small . particles in the accretion disc around a black hole move on circular geodesics of the metric . if the orbits in the disc could be mapped , this would allow spacetime mapping along the lines of ryan s theorem . two possible probes of accretion - disc structure have been identified : quasi - periodic oscillation ( qpo ) pairs and iron k lines . qpos have been used to constrain possible values of black - hole masses and spins , but there are uncertainties in the radius at which they originate , and in the resonance that gives rise to the pairs of lines . iron lines show broadening due to differential gravitational redshift and doppler shift at different points in the disc , but again their interpretation depends on unknown details of the disc geometry . in principle , the time variability of an iron line after a single flare event could constrain both the geometry and map the disc . future observations with instruments such as ixo / athena will have the time - resolution to attempt this . electromagnetic observations are generally hampered by a lack of knowledge of the physics of the material that is generating the radiation . gw systems are , by contrast , very clean since the same theory describes the spacetime and the radiation generation . while there is some hope that future electromagnetic observations will perform crude spacetime mapping , lisa emri observations will improve any previous constraints by orders of magnitude . although the bibliography of this review lists more than 500 references , fundamental tests of gravity remain the least explored sector of gw astronomy . it is also one where new discoveries may be hardest to come by even if they would be momentous if they do . space - based gravitational - wave detectors will improve certain existing constraints on alternative theories ; even more important , they will provide novel and unique opportunities to precisely characterize the poorly explored nonlinear , dynamical sector of gravitation , as well as the properties of gravitational radiation fields . these measurements will provide a definite confirmation that einstein s theory , born from insight and beauty , applies in the most extreme regimes ; or they may expose new phenomena , leading to new models for gravitational physics . the research that we have reviewed spans a broad assortment of gw observations , which probe many disparate aspects of gravitational phenomenology . some of these investigations have yet to be refined to the same level of formal rigor as other , more astrophysical applications of gw astronomy . nevertheless , they paint an exciting picture of the expected fundamental - physics payoff of space - based detectors . we expect that this will remain an active and intriguing research area for many years : thus , it is appropriate that this review should be living , and we welcome the suggestions of our readers in improving it and keeping it up to date .\noutput:\n" }, { "from": "agent", "value": "we review the tests of general relativity that will become possible with space - based gravitational - wave detectors operating in the 105 1 hz low - frequency band . the fundamental aspects of gravitation that can be tested include the presence of additional gravitational fields other than the metric ; the number and tensorial nature of gravitational - wave polarization states ; the velocity of propagation of gravitational waves ; the binding energy and gravitational - wave radiation of binaries , and therefore the time evolution of binary inspirals ; the strength and shape of the waves emitted from binary mergers and ringdowns ; the true nature of astrophysical black holes ; and much more . the strength of this science alone calls for the swift implementation of a space - based detector ; the remarkable richness of astrophysics , astronomy , and cosmology in the low - frequency gravitational - wave band make the case even stronger ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the real geographic distribution of this mycosis could be more widespread than what was previously thought . the incidence of this fungal disease is higher in the mid - and southeast usa , latin america , china , and other world areas . additionally , asymptomatic cases are escalating and are reported to predominately affect immunocompromised individuals as an acute pulmonary infection similar to mild flu - like symptoms . likewise , the most severe symptomatic form of the disease , referred to as disseminated histoplasmosis , develops most commonly in immunosuppressed patients . although antifungal therapies have been used against the fungus , there are no current alternative therapies to treat or protect against h. capsulatum infection . h. capsulatum is a dimorphic , facultative , intracellular pathogen found as a yeast phase when in host tissue . in the early stages of infection , the fungus is phagocytosed by resident alveolar macrophages , dendritic cells , and neutrophils . once phagocytosed , the fungus survives in the phagosome and consequently transforms into a yeast . in immunocompromised individuals or when left untreated , the reservoir phagocytes can travel to lymphatic tissue and spread infection . however , induction of a strong cellular immune response can contain or clear the infected phagocytes , therefore preventing the spread of the infection . an effective host defense to h. capsulatum infection is dependent on adequate activation of t cells and phagocytes . appropriately , the balance between the th1 and th2 response is fundamental for solving h. capsulatum infection , with th1 proinflammatory cytokines ifn - ( interferon - ) , interleukin - 12 ( il - 12 ) , tnf - ( tumor necrosis factor - ) , and gm - csf ( granulocyte macrophage colony - stimulating ) being essential to elicit macrophage activation and clearance of h. capsulatum . in addition , a balanced production of lipid mediators , such as prostaglandin e2 ( pge2 ) and leukotriene b4 ( ltb4 ) , is critical for the host defense in histoplasmosis , since high levels of pge2 and low levels of ltb4 impair the yeast clearance and increase the severity of this fungal disease . nitric oxide also participates in the host defense against h. capsulatum ; however , overproduction of this mediator increases the susceptibility of the host to yeast infection . in addition to cytokines and lipid mediators , a member of the galectin family , known as galectin - 3 ( gal - 3 ) , has been suggested to be involved in the immune response against h. capsulatum infection . galectins belong to an endogenous lectin family that recognizes glycans present in microorganisms and participates in the pathophysiology of inflammatory responses , infectious diseases , autoimmunity , and cancer . interestingly , galectin - 1 ( gal - 1 ) has been shown to participate in an innate and adaptive immune response to different models of experimental infections such as in trypanosoma cruzi ( t. cruzi ) , situation in which a dual role for this lectin was described . these authors showed that , in a low concentration , gal - 1 was able to decrease proinflammatory interleukin - 12 ( il - 12 ) and nitric oxide ( no ) , while in a high concentration , it has induced infected macrophage apoptosis . gal - 1 was also found to promote human immunodeficiency virus - 1 ( hiv - 1 ) infectivity ; in dengue virus infection , it could cause an inhibitory effect on virus replication . thus , several gal - 1 exogenous properties have been related to crd binding to cell surface receptors , modulating immune cell functions , migration , differentiation , activation , and cell survival . nevertheless , the interactions of this lectin with the intracellular ligands can also occur independently to carbohydrates . although gal - 1 can participate in various pathophysiological processestherefore , the present study evaluated the biological impact of the absence of gal - 1 on a murine model of histoplasmosis . while mice genetically deficient in gal - 3 ( lgals3 ) were able to clear h. capsulatum infection more efficiently than wild - type ( wt ) mice , it was reported for the first time that gal - 1 ( lgals1 ) mice are more susceptible to h. capsulatum infection compared to wt group . this unique immune phenotype suppresses the host response against the fungus and is followed by high levels of neutrophil infiltration and proinflammatory cytokines in the lungs which causes a strong anti - inflammatory response with high levels of pge2 and no . these findings indicate a novel contribution of endogenous gal - 1 to the development of a protective immune response to h. capsulatum . wt and lgals1 mice were injected with 510 h. capsulatum yeasts cells directly into the lungs and survival was monitored up to 30 days .33 % of lgals1 - infected mice survived 30 days after infection , whereas 100 % of the infected wt mice survived over that period ( figure 1 ) . to determine if the high mortality rate in lgals1 mice is correlated with impaired fungal clearance , the h. capsulatum load was quantified in the lung and spleen . considering that lgals1 mice began to die day 14 after infection and that day 15 after infection is a critical point on the evolution of experimental histoplasmosis using mutant mice and a sublethal fungus dose , on day 15 after infection , lung parenchymal histopathological analysis and quantification of fungal burden in thelgals1 - infected mice presented a higher number of yeast cells in pulmonary parenchyma ( figures 2 ( a ) and 2 ( b ) ) and higher fungal load in lung ( figure 2 ( c ) ) and spleen ( figure 2 ( d ) ) . even though infected lgals1 mice presented a higher fungal burden in the lung , an increased neutrophil influxit is known that an efficient immune response against h. capsulatum is associated with fungicidal / fungistatic effects of pulmonary infiltrated phagocytes . thus , these findings suggest that endogenous gal - 1 is required to develop a protective immune response against h. capsulatum and that gal - 1 could be associated with the control of fungal replication as an efficient anti - h . capsulatum activity along with effectors functions and regulation of tissue accumulation of neutrophils . it is well known that increased expression of inflammatory cytokines , including il - 12 , ifn - , and tnf - , is critical for the immune - protective response in h. capsulatum - infected mice . thus , to analyze the pattern of inflammatory cytokines in wt and lgals1 mice day 15 after h. capsulatum infection , the levels of il - 12p40 , tnf - , il - 1 , il - 10 , il - 4 , and il - 6 in the pulmonary homogenates were measured . there were higher levels of il - 12p40 ( figure 4 ( a ) ) and il - 1 ( figure 4 ( c ) ) and similar concentrations of tnf - ( figure 4 ( b ) ) in homogenized lungs of lgals1 - infected mice , when compared to wt infected mice . furthermore , no statistically significant differences in tnf - ( figure 4 ( b ) ) were observed , and il - 10 , il - 4 , and il - 6 ( data not shown ) were not produced in detectable levels . based on the aforementioned results , it was also analyzed whether inflammatory mediators , such as no and pge2 , are associated with increased levels of proinflammatory cytokines and consequently immunosuppression in the absence of endogenous gal - 1 in experimental histoplasmosis . it has been reported that the inhibition of cox - 2 improves the host defense against h. capsulatum . therefore , pge2 was quantified from homogenized lungs derived from infected wt and lgals1 mice on day 15 after h. capsulatum infection . the lungs of infected lgals1 mice exhibited higher levels of pge2 ( figure 5 ( a ) ) when compared to infected wt mice . thus , consistent with other published results , these findings suggest that higher levels of pge2 may contribute to susceptibility of infected lgals1 mice . interestingly , not only pge2 but also no levels in the lung of this group were increased when compared to wt ( figure 4 ( d ) ) . the immune response against h. capsulatumis mediated by th1 cells , which requires macrophages activation . the pathogenic yeast fungus replicates inside these cells and results in metabolites of arachidonic acids production , such as prostaglandins and leukotrienes . to assess the role of endogenous gal - 1 in pge2 production , prostaglandin e synthase 2 ( ptges2 ) mrna expression in peritoneal macrophages from lgals1 and wt mice infected or not with h. capsulatum in vitro was evaluated . interestingly , 24 hours after h. capsulatum infection , lgals1 macrophages had increased ptges2 mrna expression when compared to infected wt macrophages . in addition , higher levels of pge2 were detected in the supernatants 24 hours after the infection of lgals1 macrophages when compared to wt macrophages ( figure 5 ( c ) ) . thus , the in vitro results correlate with overproduction of prostaglandins in vivo ( figure 5 ( a ) ) . recently , it was reported that galectins can bind glycans not only on the host cell surface , but also on molecules on pathogens , which has been found to result in pathogen killing and modulation of immune responses against bacterial infections . to assess the binding capacity of gal - 1 on h. capsulatum surface , biotinylated - human recombinant gal - 1 ( hrgal - 1 : 1 m and 4 m ) was incubated with the yeast form of h. capsulatum . gal - 1 did not bind to the yeast form of this fungus ( figure 6 ( a ) ) although the hrgal - 1 was active , since it did bind to glycans on hl - 60 cells ( figure 6 ( b ) ) . as expected , different concentrations of hrgal - 1 ( 0.5 , 1.0 , 2.5 , 4.0 , and 10.0 m ) did not alter the viability of h. capsulatum after 24 and 48 h of in vitro incubation ( figure 6 ( c ) ) . this result suggests that the binding effect can be related to killing activity as stowell et al . thus , the yeast form of h. capsulatum seems not to express ligands for gal - 1 and indicates that the protective mechanistic effects of gal - 1 to h. capsulatum infection do not involve gal - 1 binding to the yeast . galectins have been described as regulators of immune response in models of inflammatory and infectious diseases and host pathogen recognition . gal - 1 and gal - 3 are the best studied members of the galectin family and the expression of these proteins is increased or decreased in distinct cell types following infections caused by different pathogens . previous reports demonstrate that gal - 3 participates in yeast infections ; however , the role of gal - 1 in fungal diseases has not yet been explored . although the expression of gal - 3 in dendritic cells is not upregulated in wt mice infected with h. capsulatum , mice genetically deficient in gal - 3 clear this fungal infection more efficiently than wt mice , showing that high gal - 3 expression in wt mice is not required for the participation in the immune response against h. capsulatum and may actually contribute to pathogenesis . unexpectedly , gal - 3 knockout mice are more susceptible to candida albicans infection than wt mice and the susceptibility is associated with high fungal burden in the brain . additionally , gal - 3 , but not gal - 1 , can induce yeast cell death upon binding to -1,2-linked oligomannosides on the surface of pathogenic fungus candida albicans . thus , gal - 3 and gal - 1 appear to be differentially involved in host defense mechanisms against fungal infections , and this feature may arise from the specific pathogen . in disseminated candidiasis model , the absence of gal - 3 is responsible for increased susceptibility . in the present study , in contrast to gal -3-deficient mice , the novel observation that the absence of endogenous gal - 1 increased susceptibility to h. capsulatum accompanied by higher fungal loads in therecently , it was reported that lgals1 mice infected intradermally with t. cruzi are resistant to this parasitic infection compared to their wt counterparts and this resistant phenotype could be associated with a dysfunction in the regulatory properties of gal - 1 followed by high production of th1 proinflammatory cytokines and improvement of th1 and cd8 t cells responses . however , another report from the same group described that lgals1 mice infected intraperitoneally with t. cruzi showed elevated parasitemia , less tissue inflammation , and higher mortality rates as compared to infected wt mice . these authors suggest that this discrepancy could be associated with the presence of different phagocytes at sites of infection and distinct local immune response induced by t. cruzi . based on these reports and the present data , it is suggested that the infection of lgals1 mice , intratracheally , with h. capsulatum promotes a unique immunophenotype that suppresses the host response against the fungus . this special immunological scenario is characterized by an imbalanced inflammation associated with high levels of neutrophil infiltration and proinflammatory cytokines in the lungs that causes a strong anti - inflammatory response induced by high levels of pge2 and nitric oxide that could modulate phagocyte and t cell functions . based on evidence that gal - 4 and gal - 8 can bind and kill bacteria that express a human blood group b - like antigen and a common mammalian antigen - gal , it is hypothesized that gal - 1 might have the same effect on the yeast form of h. capsulatum . however , in contrast to gal - 4 and gal - 8 killing activities toward bacteria , gal - 1 neither bound to nor killed the yeast form ( figure 6 ) . this data suggests that the ability of gal - 1 to contribute to proper control of the fungal infection arises from an indirect contribution , since gal - 1 is clearly involved in the modulation of immune response against h. capsulatum . next , it was evaluated whether the absence of gal - 1 could interfere with the recruitment of neutrophils to the lungs during the infection , since this lectin could modulate the inflammatory response . it is known that neutrophil migration to sites of infection helps the clearance of pathogens . human neutrophils are able to impair the growth of h. capsulatum yeast form , and this microbiostatic effect is mediated mostly by compounds present in the azurophil granules . moreover , in experimental histoplasmosis , depletion of gr - 1 cells , primarily neutrophils , promotes the increase in fungal load in the lungs and spleens and decreases the survival of animals even in the presence of high levels of tnf - and no . previous reports demonstrate that mice genetically deficient in gal - 1 have enhanced neutrophil emigration in response to il - 1 compared to their wild - type counterparts . furthermore , in an animal model of zymosan - induced peritonitis , exogenous gal - 1 was shown to cause decreased production of proinflammatory cytokines and expression of adhesion molecules on the surface of neutrophils , thus diminishing their rates of migration . the present results are consistent with those of others , indicating that h. capsulatum promotes intense neutrophil recruitment in the lung of lgals1 mice ( figure 3 ) ; however , these phagocytes were not able to clear the fungus in the lung pulmonary parenchyma . other authors have demonstrated that upregulation of proinflammatory cytokines / chemokines resulted in higher numbers of lung neutrophils and also reduced the capacity of the host defense to eliminate the fungus . since gal - 1 can modulate the adhesion molecules expression as well as releasing mediators of immune response , it was evaluated whether the increase of neutrophil infiltration into the lung was associated with exacerbation of cytokines during the inflammatory response against h. capsulatum infection . the intense neutrophil accumulation in the lung of lgals1 mice could be explained by high levels of il - 1 ( figure 4 ( c ) ) , since this cytokine is a chemoattractant for neutrophils . moreover , the presence of high number of neutrophils may be a major source of il - 12 detected in the lung from infected - lgals1 mice , as neutrophils have been reported to produce il - 12 . curiously , inhibition of dectin - 1 expression , a host receptor for fungal beta - glucan , reduces the severity of fungus infection and its effect was associated with decrease of proinflammatory cytokines , including il - 12 , and neutrophil infiltration . furthermore , it is known that proinflammatory cytokines , including il - 12 , are essential for host defense against h. capsulatum . conversely , on the present model , the increase of il - 12 did not promote fungal clearance in the lungs of lgals1 mice . based on these results , it may be hypothesized that the excessive production of il - 12p40 and il - 1 in lgals1 - infected mice is deleterious to the animals . interestingly , lgals1 mice are more resistant to trypanosoma cruzi infection than wild - type mice and this phenotype is associated with upregulation of ifn - and no significant production of il17a . however , the hsv - 1 infection in lgals1 mice promotes a severe disease , compare to wild - type , that is correlated with the elevated number of neutrophil infiltrations and ifn -- producing cd4 t cells and no significant change of il -17-producing t cell in the ocular . then , considering that ( i ) immunoregulatory properties of gal - 1 are associated with regulation of th 1 and th 17 responses , ( ii ) il - 12 and il - 23 share p40 subunit , and ( iii ) il - 17 / il -23-axis cytokines participate in immune response against h. capsulatum infection , further investigation should be done in order to elucidate the impact of il17 / il23 in experimental histoplasmosis in the absence of endogenous gal - 1 . in addition to cytokine production , it was analyzed whether microbicidal factors , such as no , could be modulated by the deficiency of gal - 1 , which could underlie the suppression of host defense against h. capsulatum . it was found that the deficiency of gal - 1 promotes the increase of no concentration in the lung of infected mice when compared with infected wt mice . these results are in concordance with other studies that show that gal - 1 negatively modulates the no production by activating macrophage or microglia - like cells and activated microglia from lgals1 mice produce high concentration of no . moreover , the high levels of no produced ( figure 4 ( d ) ) in the lung have no microbicidal effect on h. capsulatum , since lungs from gal - 1 lgals1 mice had higher cfu ( figure 2 ) . thus , no appears to be important for the host defense against primary infection by h. capsulatum ; nonetheless , the overproduction of no has also been shown to suppress phagocytic activities of macrophage in h. capsulatum infection and inhibit the cd4 t cells proliferation response to t. cruzi infection . alveolar macrophages are the first line of host defense in the lung against respiratory pathogens , and this phagocyte is an important source of lipid mediators , such as pge2 in infected lung . pge2 has an important role in suppression of host defense involved modulation of alveolar macrophages functions in different pulmonary infection models , such as streptococcus pneumoniae , klebsiella pneumoniae , pseudomonas aeruginosa , and recently h. capsulatum . lung and macrophages from lgals1 - infected mice produced higher levels of pge2 when compared to wt mice . then , it is hypothesized that high levels of no and pge2 in the lungs of lgals1 - infected mice inhibit the effector functions of macrophages and neutrophils against h. capsulatum . whether the absence of endogenous gal - 1 can inhibit the effector functions of neutrophils against h. capsulatum remains unknown , though . pge2 is able to inhibit il - 12 production by macrophage and dendritic cells , although lung parenchyma from infected lgals1 mice contained higher levels of il - 12 than those from infected wt mice even in the presence of high levels of pge2 . this finding is in agreement with other studies reporting that the inhibition of prostaglandin has no effects on the production of il - 12 in h. capsulatum - infected mice . in addition , the present data is similar to others , demonstrating that the immunoregulatory effects of gal - 1 ( endogenous or exogenous ) are associated with suppression of th1 cytokines , including the negative modulation of il - 12 production by activated macrophage or tolerogenic dendritic cells . because of the low yield of murine alveolar macrophages , peritoneal macrophages from lgals1 mice were used to examine the ability of endogenous gal - 1 to modulate the expression of mrna ptges2 and pge2 after h. capsulatum infection ( figure 5 ( b ) ) . the high fungus burden in lungs and spleen in infected lgals1 mice could be associated with the downregulation effects of pge2 in antimicrobial functions of phagocytes . exaggerated inflammatory response could be responsible for higher production of pge2 in lungs of h. capsulatum - infected lgals1 mice that inhibited fungal clearance , since the pge2 biosynthesis is increased under inflammatory conditions , and this prostanoid has been described to impair phagocytosis and kill by alveolar macrophages . in addition , the effector functions of phagocytes from lgals1 could be altered , since gal - 1 is a multifunctional molecule with intra - and extracellular effects . this immune suppressive effect is in line with current results , demonstrating the positive impact on mrna ptgs2 expression and pge2 secretion of the gal - 1 deficiency in macrophages from lgals1 mice after fungal infection . this data is in agreement with the results described by rabinovich and colleagues , since this lectin can reduce arachidonic acid release and pge2 secretion from activated macrophage . besides that , celecoxib treatment , a selective cyclooxygenase 2 inhibitor , improved the immune response against h. capsulatum infection through the inhibition of prostaglandin production . curiously , celecoxib induces expression of gal - 1 in activated macrophage and gal - 1 could be involved in the anti - inflammatory mechanisms of this drug . furthermore , gal - 1 inhibited the expression of activating transcription factor 3 , a negative regulator of mrna ptgs2 in macrophage . despite that , further investigations are needed to elucidate the mechanism by which gal - 1 inhibits ptgs2 expression . it has now been shown that pge2 is a damp ( damage - associated molecular patterns ) and is induced and released by dying cells , which leads to suppressed expression of genes associated with inflammation and thereby limits immunostimulatory activities . also , pge2 is downregulated in human systemic inflammatory diseases and mice with reduced pge2 exhibit systemic inflammation . in summary , the present results demonstrate that the endogenous gal - 1 plays an important role in host defense against histoplasma capsulatum modulating of pge2 , il - 12 , and no production , as well as pulmonary neutrophil accumulation . future studies are needed to better understand the cellular and molecular mechanisms in which endogenous galectin - 1 could participate in host defense against fungus infection . six - to - eight - week - old wild - type ( wt ) male mice and mice genetically deficient in gal - 1 ( lgals1 ) , both in a c57bl / 6j background , were housed and bred at the animal facility of the school of pharmaceutical sciences of ribeiro preto ( university of so paulo , brazil ) . wild - type mice were originally purchased from the jackson laboratory ( bar harbor , me , usa ) and lgals1 mice were provided by dr . richard d. cummings ( department of surgery , beth israel deaconess medical center and harvard medical school , boston , ma , usa ) . the experimental protocol was approved and conducted in accordance with guidelines of the institutional animal care committee . to check the depletion of lgals1 , gal - 1 expression ( mrna and protein ) analysis on wt and lgals1 cellswere performed as previously described using conventional rt - pcr and western blot , respectively ( data not shown ) . h. capsulatum strain was isolated from a patient at the clinical hospital , school of medicine of ribeiro preto , university of so paulo , and the characterization and preparation of h. capsulatum yeast cells were performed as previously described . the yeast cultures were used at 90 % viability according to fluorescein diacetate ( sigma - aldrich , st . mice were given intratracheally ( i.t . ) dispersion containing 100 l phosphate buffered saline ( pbs , vehicle control ) or a sublethal dose in pbs ( 510 yeasts / animal ) . the appropriate inoculum size was chosen based on procedure described by s - nunes and colleagues . on day 15 after infection , both uninfected and infected mice were euthanized in a co2 chamber , and lungs and spleens were collected for analyses . h. capsulatum - infected mice were euthanized on day 15 after infection and tissue samples were harvested . lung sections ( 5 m ) were embedded in paraffin blocks and stained with grocott 's methanamine silver ( gms ) and quantification of yeasts was expressed as yeast / mm ( original magnification : 400x ) . also , fungal burden was determined from homogenized lung and spleen ( mixer homogenizer ; labortechnik , staufen , germany ) as previously described . serial dilutions of these tissue homogenates were plated onto bhi blood agar and incubated at 37c for 21 days . the results were expressed as mean colony - forming units ( cfu ) per gram of lung sem ( cfu / g ) or cfu per whole spleen sem ( cfu / spleen ) . lungs were collected , fixed in 10 % formaldehyde , and embedded in paraffin blocks . for neutrophils analyses , lung sections ( 5 m ) were stained with hematoxylin and eosin ( h & e ) and the cells were quantified in the ocular lens containing 1010 graticules ( 0.0624 mm each in magnifications : 400x ) . lungs were collected 15 days after infection , weighed and homogenized ( mixer homogenizer ; labortechnik , staufen , germany ) in 2 ml of rpmi1640 ( sigma ) and the supernatants were stored at 70c until being assayed . commercially available elisa antibodies were used to measure tnf - , il - 1 , il - 12p40 , il - 10 , il - 4 , and il - 6 ( bd opteia elisa sets ; bd pharmingen ) according to the instructions of the manufacturer . pge2 from lung homogenate and from in vitro assay ( in vitro assay is described below ) were purified by sep - pak c18 cartridges according to the manufacturer 's instructions ( waters corp . , milford , ma ) . quantification of pge2 was assessed also by elisa ( cayman chemical , ann arbor , mi ) and the results for cytokines and pge2 are expressed in ng / ml . the sensitivity of the assay was 10 pg / ml . nitrite ( no2 ) concentrations ( m ) in lung homogenates was measured by griess reaction using a standard curve with serial dilutions of nano2 ( sigma - aldrich ) . griess reagent was used in order to measure no levels indirectly from nitrite as described previously . wt or lgals1 peritoneal macrophages ( 510 cells / well ) were incubated with h. capsulatum ( moi 1 : 1 ) during 2 and 24 hours . pge2 was assessed in the supernatants 24 hours after infection and expression of mrna was performed in plated macrophages 2 and 24 hours after h. capsulatum exposure . cdna ( complementary dna ) was synthesized from 600 ng of total rna using random primers ( high capacity cdna reverse transcription kit , applied biosystems , temecula , ca ) . aliquots of 2 l of the total cdna were amplified by qrt - pcr ( stepone plus , applied biosystems , singapore ) using the primers ( idt , integrated dna technologies , california , usa ) for ptges2 ( the gene encoding prostaglandin e synthase 2 , mm.pt .58.7480753 ) and probe ( taqman gene expression assay , applied biosystems , foster city , usa ) . amplification was performed in duplicate under the following conditions : denaturation at 95c for 10 min , followed by 40 cycles of 95c for 15 s and 60c for 1 minute . relative quantification was performed using the ct method and plotted as fold increase or fold regulation by log2 . briefly , purified hrgal - 1 was treated with 100 mm iodoacetamide ( sigma - aldrich ) in 100 mm lactose / pbs overnight at 4c . to ensure that hrgal - 1 samples were endotoxin - free , detoxi - gel endotoxin removing gel ( pierce biotechnology , rockford , il ) was used and hrgal - 1 activity was assessed by haemagglutination ( data not shown ) . to measure the capacity of gal - 1 to bind on yeast form of h. capsulatum , 1 m and 4 m biotinylated - hrgal - 1 were incubated for 1 hour at 4c , in presence or absence of 20 mm lactose or sucrose ( sigma - aldrich ) . after washing , yeasts were incubated with streptavidin - fitc ( jackson ir ) for 30 minutes at 4c , washed , and formalin - fixed ( 1 % in pbs ) . labeled cells were acquired on a facs canto ( becton dickinson , mountain view , ca , usa ) and analyzed in the diva software ( becton dickinson ) . as a control , we used hl - 60 cells obtained from the american type culture collection ( atcc , manassas , va ) and maintained in rpmi medium supplemented with 10 % fetal bovine serum . to test h. capsulatum viability in a presence of gal - 1 , we incubated , in vitro , several hrgal - 1 concentrations ( 10 , 4 , 2.4 , 1 , and 0.5 m ) with 110 yeast cells during 24 and 48 h. the relative fluorescent units ( rfu ) using a plate reader were detected ( 560590 nm ) in order to analyze the number of yeast cells metabolically active using the dye resazurin reagent ( sigma - aldrich ) . comparisons were performed using an anova followed by a bonferroni posttest by the prism 4.0 statistical program ( graphpad software , san diego , ca ) . survival analyses were performed using the mantel - cox log - rank ( chi - squared ) test .\noutput:\n" }, { "from": "agent", "value": "histoplasma capsulatum is a dimorphic fungus that develops a yeast - like morphology in host 's tissue , responsible for the pulmonary disease histoplasmosis . the recent increase in the incidence of histoplasmosis in immunocompromised patients highlights the need of understanding immunological controls of fungal infections . here , we describe our discovery of the role of endogenous galectin - 1 ( gal - 1 ) in the immune pathophysiology of experimental histoplasmosis . all infected wild - type ( wt ) mice survived while only 1/3 of lgals1 / mice genetically deficient in gal - 1 survived 30 days after infection . although infected lgals1 / mice had increased proinflammatory cytokines , nitric oxide ( no ) , and elevations in neutrophil pulmonary infiltration , they presented higher fungal load in lungs and spleen . infected lung and infected macrophages from lgals1 / mice exhibited elevated levels of prostaglandin e2 ( pge2 , a prostanoid regulator of macrophage activation ) and prostaglandin e synthase 2 ( ptgs2 ) mrna . gal - 1 did not bind to cell surface of yeast phase of h. capsulatum , in vitro , suggesting that gal - 1 contributed to phagocytes response to infection rather than directly killing the yeast . the data provides the first demonstration of endogenous gal - 1 in the protective immune response against h. capsulatum associated with no and pge2 as an important lipid mediator in the pathogenesis of histoplasmosis ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: it is used clinically in medicine to treat a range of cancerous and noncancerous conditions . methotrexate is currently used in gynaecology to treat disorders arising from trophoblastic tissue , namely , ectopic pregnancy and gestational trophoblastic disease . whilst the incidences of these conditions in pregnancy are relatively rare ( ranging from 0.7 % for gtd to 1 - 2 % for ectopic pregnancy ) , their impact on the lives of young women of reproductive age , both in terms of mortality and morbidity ( especially loss of reproductive potential ) , are significant . methotrexate has contributed to alleviating some of the disease burden of ectopic pregnancy , where it affords approximately 25 % of women a nonsurgical and fertility - preserving treatment option . methotrexate has dramatically improved survival outcomes in gestational trophoblastic neoplasia , where surgery is now only occasionally used as an adjunct to treatment . this article reviews methotrexate and its mechanism of action , gestational trophoblastic neoplasia and ectopic pregnancy , and how modern treatment protocols using methotrexate to medically treat these two conditions developed . methotrexate was one of the first drugs synthesized for a specific chemotherapeutic purpose in situ folic acid inhibition for the treatment of acute lymphoblastic leukaemia ( all ) in children . the factor later shown to be folic acid was discovered by missionary physician lucy wills in india in the 1930s , when she used marmite to treat megaloblastic anaemia in impoverished , pregnant textile workers . in the 1940s , this factor was isolated from spinach leaves and called folic acid ( folium being latin for leaf ) . at this time , american pathologist / pediatrician sidney farber had noted the morphological similarities between all and megaloblastic anaemia and trialled folic acid in the treatment of children with all ; however , it paradoxically accelerated disease progression . folic acid - deficient diets were subsequently shown to decrease the leukaemia cell count , and this led to the development of folic acid antagonists . methotrexate was the second drug to be developed for this purpose by a group of researchers at the lederle laboratories in 1949 . its application to the treatment of a woman with terminal choriocarcinoma in 1956 produced the first cure of a solid tumour by chemotherapy , and its use in the treatment of gtn and ectopic pregnancy expanded from there . it does so by competitively binding with the enzyme dihydrofolate reductase with much greater affinity than folic acid . this prevents the conversion of dihydrofolate to tetrahydrofolate , which is essential in the de novo synthesis of purine nucleotides and thymidylate , which are themselves essential substrates of dna synthesis , repair , and cell proliferation ( figure 1 ) . methotrexate thus blocks cell proliferation in the s phase of the cell cycle during which dna replication occurs , making rapidly dividing cells such as trophoblast especially susceptible to its action . it also means that methotrexate has a nonspecific mechanism of action , and with this comes the potential for numerous side effects . methotrexate has a wide range of indications that extend beyond its original design for the treatment of hematological malignancy . it is still used for the treatment of neoplasms such as leukaemias and lymphomas , but also lung cancers , breast cancer , head and neck cancers , osteosarcomas , bladder cancer , and gtn . it has been found to have an immunomodulatory effect in autoimmune conditions such as rheumatoid arthritis , although its mechanism of action here remains unknown , and psoriasis , where it is thought to impede the rapid turnover of skin cells characteristic of the condition , and is used occasionally in crohn 's disease , multiple sclerosis , and psoriatic arthritis . it is also used in the treatment of ectopic pregnancies by extension of its use in gtn . owing to its nonspecific actions on cell division , methotrexate is associated with toxicities and side effects that include every organ system . the exact likelihood and incidences vary slightly depending on the condition being treated , the route of administration , the dosage , and length of treatment . by its mechanism of actionmethotrexate preferentially targets rapidly dividing cells ; therefore , the hematological , gastrointestinal , and dermatological systems which feature a high turnover of cells are the most likely to display signs and symptoms of toxicity such as neutropenia and generalized myelosuppression , nausea , vomiting , diarrhoea , and gastrointestinal inflammation as well as generalized erythema , rash , photosensitivity , and alopecia . these side effects have been greatly ameliorated in the field of gynaecology by the development of a low , single - dose protocol in the treatment of ectopic pregnancies , and to some extent with the use of folinic acid ( a form of tetrahydrofolate ) rescue in gtn chemotherapy protocols . gestational trophoblastic disease ( gtd ) consists of a range of premalignant and malignant tissues that arise from trophoblastic cells in association with any type of gestational event . the premalignant forms of the disease are called molar pregnancies and comprise over 90 % of gtd . molar pregnancies consist of abnormally proliferative trophoblastic tissue and occur after an abnormal fertilization event . there are two types of molar pregnancies : complete hydatidiform mole ( chm ) , where there is no maternal chromosomal material in the ovum and either one sperm fertilizes the ovum and replicates its dna ( androgenetic monospermic - 90 % ) or two sperm fertilize the empty ovum ( androgenetic dispermic - 10 % ) , and partial hydatidiform mole ( phm ) where an apparently normal ovum with maternal chromosomal material is fertilized by two sperm resulting in triple the normal amount of chromosomal material ( biparental triploid ) . a rare form of biparental chm is associated with an autosomal recessive mutation on chromosome 19q ( nlrp7 ) and is thought responsible for recurrent molar pregnancy . malignant forms of gtd mainly consist of invasive mole and choriocarcinoma , and occasionally the rare placental - site trophoblastic tumour ( pstt ) . it was n't until 1895 that an association between pregnancy and gtd was confirmed when marchand determined that the tumours arose from fetal cell lines . prior to the 1950s and the era of chemotherapy , choriocarcinoma , the most aggressive form of gtn , was fatal in 9095 % of cases where metastases were present . in 1956 , the antifolate drug methotrexate ( see above ) was given to a young woman with advanced metastatic choriocarcinoma who was expected to die within a matter of months . the idea to test methotrexate for this condition came from an earlier observation where methotrexate given to a patient with malignant melanoma unexpectedly eradicated the presence of hcg from her urine . this terminally ill woman with choriocarcinoma not only got better with methotrexate treatment but was discharged home four months later with no identifiable disease . the incidence of molar pregnancies is notoriously difficult to determine , as the diagnosis relies on highly specialized histopathological examination . furthermore , estimates of the incidence of molar pregnancies are calculated against either total number of pregnancies , deliveries , or both , creating confusion , and these statistics themselves are prone to underreporting . estimates of the incidence of molar pregnancy in the western world including australia are 0.51 / 1000 pregnancies , whilst the much higher incidence in asia ( 1 - 2/1000 pregnancies in japan and china and up to 12/1000 pregnancies in indonesia ) is believed to be genuinely reflective . extremes of maternal age and previous molar pregnancy are the two most strongly proven risk factors . pregnancies occurring during teenage years carry a 1.52-fold increased risk of molar pregnancy , whereas , in pregnancies occurring when a woman is 40 - year old or more , the risk is increased 57.5-fold . similarly , if a woman has had one previous molar pregnancy , her risk of recurrence in a future pregnancy is 1 % compared to 0.1 % of the general population , and if she has had two or more , this risk rises to between 16 and 28 % . other risk factors such as maternal blood group , smoking , parity , and oral contraceptive pill use have not been consistently proven ; however , the worldwide distribution of areas with high levels of vitamin a ( beta carotene ) deficiency , which causes abnormal spermatogenesis and spontaneous abortion in rhesus monkeys , correlates with areas with a high incidence of molar pregnancy . molar pregnancies have malignant potential , with local invasion a feature in 15 % of cases and / or metastases in 4 % . complete moles have a higher rate of persistence and neoplastic potential at 630 % of cases , compared to 0.53 % after partial mole . risk factors for developing invasive , persistent disease are : serum hcg levels 100,000 iu / l at diagnosis , associated large ovarian theca lutein cysts ( 6 cm ) , uterine size larger than expected for dates , and maternal age 35 y.o . . choriocarcinoma and pstt , the other forms of gtn , occur more frequently after nonmolar pregnancies at a rate of between 1 : 20,000 and 50,000 pregnancies . approximately 25 % of cases , however , still occur after complete molar pregnancy , and molar pregnancies precede 90 % of cases of gtn . the advent of chemotherapy changed metastatic gtn from a fatal disease in 9095 % of cases to being curable in 85 % of cases . for women with low - riskhowever , despite a good 5 - year - survival rate of 89.5 % , there is scope for further improvement in the management of gtn . mortality from choriocarcinoma after nonmolar pregnancy is 21 % compared to 6 % after molar pregnancy and is mainly due to late diagnosis when the disease is already advanced . cost - effective screening or surveillance measures to identify women with gtn after nonmolar pregnancies would potentially help to further improve survival by diagnosing the condition earlier in this cohort . newer agents with greater efficacy and lesser toxicity could greatly improve the care of women with this condition . first - line treatment for molar pregnancies is suction curettage , and indeed the majority of molar pregnancies are diagnosed after histopathology testing of products of conception from this procedure . this is because gtd presents similarly to and is frequently misdiagnosed as incomplete / missed miscarriages , and even ectopic pregnancy . once the products of conception have been removed surgically and the pathological diagnosis confirmed as either complete or partial molar pregnancy , patients are followed up with serial serum and / or urinary hcg levels until they normalize ( 598 % of women who develop gtn ( invasive mole ) will be identified this way within the first 6 months after surgical evacuation . serum / urinary hcg levels should be measured at least every 2 weeks , and women whose hcg normalizes within 56 days have a reduced risk of developing gtn . they are followed up for a further 6 months , and if their hcg levels remain normal , they are then discharged from surveillance . of the women whose hcg took longer than 56 days to normalize , a study by sebire et al . showed that extended surveillance for 2 years picked up only 1 additional woman who went on to develop gtn and required treatment . hence since 2007 , women whose hcg takes longer than 56 days to normalize are followed up for 6 months from the time of hcg normalization . a total of 3 of 6701 women ( 0.05 % ) who went on to develop gtn were missed by this surveillance protocol and represented with clinical symptoms . if hcg followup for gtd detects a persistence or rise in levels , invasive and therefore malignant forms of gtd , called gestational trophoblastic neoplasias ( gtn ) , are assumed . the federation of gynaecologists and obstetricians proposed the following consensus diagnostic criteria of gtn using hcg surveillance : ( 1 ) a hcg level plateau of four values 10 % over 3 weeks , ( 2 ) a hcg level increase of more than 10 % of three values over 2 weeks , and ( 3 ) persistence of detectable hcg for more than 6 months after curettage . gtn can , however , occur after any form of pregnancy ; approximately 50 % follow a normal pregnancy , 25 % after molar pregnancy , and the remaining 25 % after other gestational events such as ectopic pregnancies and miscarriages . those occurring after a nonmolar pregnancy generally present later and with more advanced disease as they are not identified through hcg surveillance but through clinical presentation and often carry a worse prognosis as a result . it carries high risk of uterine perforation and in particular , significant haemorrhage , as trophoblastic tissue is highly vascular and prone to arteriovenous malformations in gtn . more than 50 % of gtn patients will still need chemotherapy after a repeat curettage ; therefore , chemotherapy is the preferred first - line treatment . for women who have completed their families , hysterectomy is an option to treat gtn apparently confined to the uterus ; however , because of gtns ability to micrometastasise very early , this does not obviate the need for hcg surveillance or the possibility of requiring chemotherapy . the form of chemotherapy ( single agent versus multiple agents ) is determined by the modified who prognostic index score ( pis ) of the patient ( table 1 ) . unlike other cancers where the staging ( i.e. , anatomical spread ) of the tumour best determines management and correlates to prognosis , it is the presence of certain risk factors that has been shown to correlate most highly with treatment outcome and prognosis in gtn . low - risk assessment indicates that the patient is likely to respond favourably to single - agent chemotherapy , and high - risk patients require more aggressive , multiagent chemotherapy to achieve disease remission . the figo staging of gtn is still used to describe anatomical spread of the disease ( table 2 ) . low - risk disease is defined as a pis of 06 and represents approximately 95 % of gtn patients . these women are highly likely to respond to single - agent chemotherapy with either methotrexate or actinomycin d ( a very old antibiotic with anticancer activity through inhibition of dna replication ) , the two most widely used first - line agents . various methotrexate regimens are used , with little evidence of the superiority of one regimen over the other . the remission rate of methotrexate therapy ranges from 50 to 90 % depending on the route , dose , frequency of administration , and patient selection criteria used . some studies suggest that actinomycin d is more likely to induce remission than methotrexate ; however , it also seems more likely to cause toxicity such as alopecia . an 8 - day multidose methotrexate protocol with intervening folinic acid ( to minimize toxicity ) was first suggested by bagshawe and wilde in 1964 , and this regimen is the first - line treatment for low - risk disease used by large centres for trophoblastic disease management and research in both the us and the uk , and hence the most widely used regimen in the world . it achieves remission in 90 % of low - risk stage i patients and 70 % of low - risk stage ii - iii patients and is associated with low toxicity 15 % patients experience nausea , 5 % vomiting , and approximately 2 % develop mouth ulcers , sore eyes or chest or abdominal pain from pleuritic or peritoneal serositis . if first - line treatment fails , treatment with the alternate first - line agent ( methotrexate or actinomycin d ) or even multiagent chemotherapy are used to attain an overall survival rate of nearly 100 % . multiagent chemotherapy is used to treat high - risk gtn , defined as stage iv disease or stage ii - iii disease with a pis of 7 or above , as well as pstt and treatment - refractive low - risk disease . again , a wide variety of regimens are employed worldwide , with very little evidence to show superiority of any one regimen . the most widely used multiagent chemotherapy regimen ema - co - consists of : etoposide , methotrexate , actinomycin d , cyclophosphamide , and vincristine ( oncovin ) . it achieves a 5 - year - survival rate of 86.5 % and is a relatively well - tolerated regimen , with alopecia being the commonest side - effect , high - grade haematologic toxicities experienced by less than 2 % of patients , and more than half of patients retaining their fertility . there are no randomized controlled clinical trials comparing ema - co to other combination chemotherapies . other combination therapies include ema ( etoposide , methotrexate , and actinomycin d ) with one retrospective study suggesting similar efficacy but inconclusively less toxicity compared to ema - co , and mac ( methotrexate , actinomycin d , and chlorambucil ) which in a retrospective study has much lower durable remission rates compared to ema - co and requires a greater number of cycles to achieve remission . women with what we now call low - risk disease would have frequently lost their fertility through hysterectomy , which was the mainstay of treatment . those with high - risk disease inevitably died from the condition . methotrexate not only replaced surgery as a treatment option , to this day it is used to cure almost 100 % of women with low - risk disease and up to 86 % of women with high - risk disease in combination with newer chemotherapeutics . an ectopic pregnancy is one that implants outside of the uterus , in one of the fallopian tubes in 95.5 % of cases , but potentially anywhere in the abdominal and pelvic cavities . the name is derived from the greek word ektopos , meaning out of place , and the condition has been described in medical literature since the 11th century when the arabic physician abulcasis extracted a fetus from a swelling he drained through the abdominal wall . it was considered a universally fatal accident until the 19th century , when attempts such as vaginal section , maternal starvation , purging , bleeding , strychnine administration , and fetal morphine injection improved the survival prognosis to between 72 and 99 % . the incidence of ectopic pregnancies is between 1 - 2 % of all pregnancies . recognized risk factors fall into two categories : contraceptive failure , where an intrauterine device has not prevented fertilisation and is associated with a 3 - 4 % risk of ectopic pregnancy , and reproductive failure , where risk factors include a history of pelvic inflammatory disease ( especially chlamydia trachomatis ) , tubal damage from other causes such as previous surgery , previous ectopic pregnancies , smoking , advancing maternal age , infertility , and assisted reproductive techniques . ectopic pregnancy is still a potentially life - threatening condition , as the invasive and angiogenic nature of trophoblastic tissue outside of the specialized lining of the uterus means that the growing pregnancy can disrupt maternal vasculature and cause fatal haemorrhage . the advent of modern surgical techniques , anaesthesia , blood transfusions , and antibiotics in the early 20th century , and more recently ultrasound and medical treatment for the condition in the late 20th century , have seen the mortality of ectopic pregnancy fall to 0.5 deaths per 100,000 live births in the us , 0.47 per 100,000 maternities in the uk , and 0.13 per 100,000 births in australia . ectopic pregnancies were increasingly described in 17th and 18th century france , either at autopsy or during abdominal surgeries . in america , the first abdominal surgery for ectopic pregnancy was performed in 1759 by john bard , and surgical management became increasingly attempted in the 19th century . the survival rate of women who were operated on in the 1800s , however , was 5 in 30 , worse than the 1 in 3 who survived with no intervention . robert lawson tait , an eminent british surgeon , described treatment of ruptured ectopic pregnancy by ligating bleeding vessels at laparotomy in 1884 . as operative techniques have developed and improved , laparoscopy has replaced laparotomy as the preferred approach , mainly due to the significant cost savings it confers . this is a result of shorter operating time , less intraoperative blood loss , shorter hospital stay and shorter convalescence associated with laparoscopy as opposed to laparotomy . however , systematic review suggests that the laparoscopic approach is significantly less successful than laparotomy in eliminating ectopic pregnancy ( or 0.28 , 95 % ci 0.090.86 ) , mainly due to a higher incidence of persistent trophoblastic tissue after salpingostomy ( or 3.5 , 95 % ci 1.111 ) . two techniques are described to remove the ectopic pregnancy from the fallopian tube salpingectomy , where the pregnancy is removed en bloc with the tube and salpingostomy , where an incision is made on the fallopian tube over the swelling , the ectopic pregnancy carefully removed with forceps or irrigation and the incision either closed or left to heal by secondary intention . there are no prospective studies comparing subsequent fertility rates after either salpingectomy or salpingostomy , however , retrospective studies suggest no significant difference . salpingostomy is , however , associated with a 58 % risk of persistent trophoblastic tissue and is less cost effective as a result of the subsequent monitoring and treatment that this necessitates . salpingectomy is considered preferable when there is significant haemorrhage and / or damage to the tube , when ectopic pregnancy has recurred in the same fallopian tube and when future pregnancies are not desired . a prospective , randomized control trial is currently underway to evaluate whether one technique is better than the other in the management of women with ectopic pregnancies and healthy contralateral tubes who wish to conceive in future . in the meantimeextirpative surgery remained the only effective medical intervention for ectopic pregnancy until medical management was ( re - ) introduced in the 1980s . methotrexate was first used in diagnosed ectopic pregnancies in the 1960s to aide safe surgical removal of the placenta from its abdominal implantation sites in second - and third - trimester cases . in the 1980s , the use of methotrexate for treatment of ectopic pregnancies was based on its use in gtn , that is , fixed , multidose regimens with intervening folinic acid rescue . these were full chemotherapeutic doses , which although achieving cure , also produced significant side effects in women . the potential of methotrexate / folinic acid therapy as an outpatient treatment for ectopic pregnancy was first explored by stovall et al . in 1989 . at this time , however , the gold standard of diagnosis of ectopic pregnancy was by direct visualization at surgery , as ultrasound was still too crude an instrument to rely upon in this potentially life - threatening situation . surgery as part of the diagnostic logarithm of ectopic pregnancy heavily negated the benefits of then proceeding to medical management , both in terms of cost effectiveness and acceptability to patients . transvaginal ultrasonography ( tvus ) became increasingly available in the late 1980s , and by the mid 1990s sensitivity and specificity were calculated at 84.4 and 98.9 % , respectively , . this rapid technological advancement and improvement in image quality meant that , by the mid to late 1990s , tvus became the preferred means of diagnosing ectopic pregnancy although laparoscopic visualization remains the gold standard for diagnosis . stovall et al . remained the pioneers of outpatient treatment of ectopic pregnancies with methotrexate and undertook much of the research that underpins the current single - dose regimen and monitoring protocol used worldwide today . their first trial with the aim of using a single dose of methotrexate to treat ectopic pregnancy was published in 1991 , with a cure rate of 96.7 % . they included tvus in a nonsurgical workup logarithm of patients with suspected ectopic pregnancies from 1993 and developed a monitoring protocol which is based on serial serum hcgs taken on day 1 , 4 , 7 , and weekly until resolution . efficacy of treatment is determined when there is a 15 % fall in serum hcg between day 4 and day 7 . this definition of treatment success has a positive predictive value ( ppv ) of 93 % , with a sensitivity of 93 % and a specificity of 84.2 % . if there is not a 15 % fall in serum hcg between day 4 and day 7 , a second ( and third ) intramuscular injection of methotrexate ( 50approximately 20 % of patients will require more than one dose of methotrexate to achieve hcg normalization . the use of methotrexate in the treatment of ectopic pregnancy is limited by its efficacy , which drops sharply from 96 % at hcg serum levels between 2000 and 4999iu / l , to 86 % for serum hcg levels between 5000 and 9999 iu / l ( or 3.76 , 95 % ci 1.1612.33 ) . this necessarily limits the number of women with ectopic pregnancies eligible for medical management at the time of diagnosis . methotrexate has been combined with mifepristone ( ru486 ) , a progesterone antagonist , in the treatment of stable ectopic pregnancies . two trials have shown that single - dose methotrexate was slightly less successful at curing ectopic pregnancy than when 600 mcg of mifepristone was added orally ( or 0.84 , 95 % ci 0.711.0 ) . in addition to the borderline significance , van mello notes that the cohorts of women featured relatively low starting serum hcgs ( between 346 and 1,679 iu / l ) , hcg itself being the strongest prognostic indicator of medical treatment success . other medical treatments such as prostaglandins and / or hyperosmolar glucose have been compared to treatment with systemic methotrexate . prostaglandins alone or in combination with hyperosmolar glucose showed no difference in treatment success or side effects compared to methotrexate alone , and a study examining methotrexate versus hyperosmolar glucose was abandoned due to a high failure rate in the latter group ( or 0.30 , 95 % ci 0.052.0 ) . alternative means of administering methotrexate have also been studied , for example direct injection into the tubal mass at laparoscopy or with ultrasound guidance trans - vaginally . both methods require clinicians with a higher skill set than that required for systemic administration of methotrexate and are less successful treatments than laparoscopic salpingectomy . hence , systemic methotrexate , particularly the single - dose regimen , remains the only medical treatment of ectopic pregnancy in common clinical use . most centres use a protocol to carefully select which women diagnosed with ectopic pregnancies are suitable for medical outpatient treatment with single - dose systemic methotrexate . this is determined primarily by the haemodynamically stable condition of the woman and lack of clinical evidence of ectopic pregnancy rupture : blood pressure , pulse rate and oxygen saturation within normal limits , no evidence of guarding or rigidity on abdominal examination , normal red blood cell indices on blood tests , and minimal or no evidence of blood in the pouch of douglas on tvus . additionally , determinants of likelihood of medical treatment success are assessed when deciding on whether a woman is suitable for medical treatment of her ectopic pregnancy . iu / l , a gestational sac size of less than 3 - 4 cm , and no fetal heart visualized on tvus . systemic methotrexate has been compared to laparoscopic salpingostomy as a treatment for tubal ectopic pregnancy . multidose methotrexate was comparable to laparoscopic salpingostomy in terms of treatment success in women with ectopic pregnancies of any size or starting serum hcg level ( or 1.8 , 95 % ci 0.734.6 ) ; however , it was associated with significantly greater incidence of side effects ( 60 % versus 12 % ) and poorer health - related quality of life ( p 0.05 ) . multidose methotrexate was also a more expensive treatment option . single - dose systemic methotrexate compared to laparoscopic salpingostomy in women with selected ectopic pregnancies ( less than 4 cm on tvus and with starting serum hcgs less than 10,000 iu / l ) was a far less effective treatment for ectopic pregnancy ( or 0.38 , 95 % ci 0.200.71 ) , however , when allowing for additional doses of methotrexate if serum hcg was falling inadequately , there was no difference in treatment success compared with laparoscopic salpingostomy ( or 1.1 , 95 % ci 0.522.3 ) . methotrexate therefore has an established and well - proven role in the treatment of ectopic pregnancy , and although its use is limited by serum hcg level and to a lesser extent , ectopic pregnancy size , it nevertheless confers cost , fertility , and arguably improved treatment - related quality of life and recovery benefits to approximately one quarter of women with ectopic pregnancies .\noutput:\n" }, { "from": "agent", "value": "methotrexate was developed in 1949 as a synthetic folic acid analogue to compete with folic acid and thus interfere with cell replication . while initially developed as a potential treatment for acute lymphoblastic leukaemia , a serendipitous observation led to methotrexate 's use to effect the dramatic cure of a case of advanced choriocarcinoma . this prompted the exploration for the potential of methotrexate to treat other conditions involving disordered trophoblastic tissue . methotrexate has subsequently revolutionized the treatment of two pregnancy - related conditions gestational trophoblastic neoplasia and ectopic pregnancy . this article reviews the development of modern treatment protocols that use methotrexate to medically treat these two important gynaecological conditions ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the concept of a reference group and its potential influence on an individual has been know at least since the landmark publication of merton ( 1949 ) , but its beginnings can be traced to cooley ( 1902 ) . a brief definition of a reference group is given in park and lessig ( 1977 ) :( ... ) a reference group is defined to be an actual or imaginary individual or group conceived of having significant relevance upon an individual s evaluations , aspirations , or behavior . ( ... ) a reference group is defined to be an actual or imaginary individual or group conceived of having significant relevance upon an individual s evaluations , aspirations , or behavior . the present paper uses the concept of a reference group in a very broad sense as defined above . the general discussion regarding the concept of a reference group is beyond the scope of this paper . a brief discussion of the history of the concept of a reference group and its relevance can be found in dawson and chatman ( 2001 ) . suppose that each individual in the population uses a product of one of two alternative brands . once in a while the product breaks and needs to be replaced with a new one . at this time , an individual tries to determine which brand is used by the majority of a population . he selects at random a group of \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ k \\ in \\ mathbb { n } $ \\ end { document } k individuals . he chooses a brand used by the majority of those in the reference group with the probability ( 0,1 ) , referred to as the follow - up probability . this procedure is repeated in time and leads to fluctuations of the share of each brand in the market . the market share of the first brand at any given time t is denoted by x ( t ) . the two parameters , the size of a reference group k and the follow - up probability , are exogenous . the size k of the reference group governs the precision of information that an individual gets while choosing a brand .1 the follow - up probability is the measure of affect s strength of an individual for the group . the strength of the influence of the group on the individual thus measures how strongly an individual wants to be associated with the majority of a population . the value = 1/2 is referred to as the neutral position larger values indicate the positive attitude to the information , while lower values indicate the negative attitude to the information . the main issue investigated in the present paper is the isolated effect of the reference groups on the market share of a particular brand . the second point concerns the dependence of equilibrium on the follow - up probability and the size of a reference group k. it is shown that , depending on the follow - up probability , there are two distinct types of model behavior , i.e. the model is not structurally stable for any k. the ( pitchfork ) bifurcation occurs for relatively high values of the follow - up probability provided that the size of a reference group is small , which may be interpreted as the negligible effect of the reference group in certain circumstances . the rest of the paper is organized in the following way . in section 2 , a large but finite population of a size \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ n \\ in \\ mathbb { n } $ \\ end { document } n of individuals is assumed . at each period t = 0 , ,2 , , where 0 , there is a fraction of the population using the first brand . the learning algorithm employed by members of the population is very simple . at each period t , a single individual is selected at random .2 this individual randomly chooses a group of k persons from the population , referred to as the reference group .3 an individual in question determines which alternative is in the majority in a reference group and chooses this alternative with the probability ( 0,1 ) . the probability of following the majority in a reference group is called the follow - up probability . this process is repeated during every period . in the above construction , the time is assumed to be discrete , t = 0 , ,2 , , and the size of a population n is finite . the state of a population can be described in several different ways , but because the model is concerned only with the market share of each brand , it is described by the share of a population x ( t ) using the first brand . given that the size of a population n is finite , the set of possible states of a population { 0,1 / n ,2 / n , , ( n1 ) / n ,1 } is also finite . the procedure of brand selection defines the transition probabilities between the states of a population . these probabilities are denoted by p ij ( x ) , that is , p ij ( x ) is the probability that a single individual changes the brand from the i - th alternative to the j - th alternative , i , j = 1,2 , given the state of a population x. the above model is , in fact , a finite markov chain . this markov chain can be studied directly , but it is easier to consider a system of differential equations of the form 1 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left \\ { \\ begin { array } { llll } \\ hspace * { 1.5 pc } \\ dot { x } & = & p _ { 21 } ( x ) - p _ { 12 } ( x ) , \\ \\ . system ( 1 ) approximates4 the average behavior of the markov chain ; cf . ( 1 ) is derived by taking the limit n with = 1 / n but for the approximation to hold , it is enough to have the size n of a population finite and large enough . the size k of a reference group defines , together with the follow - up probability , the transition probabilities and is not related in any way to the size of a population but only to the state of a population , that is , as long as the state of a population is x and both k and are fixed , then the size n of a population can be arbitrary . it is assumed only that n is larger than k. in fact , in the context of the background story , it is better to think of k as a much smaller number than the size n of a population . it is clear that , for two alternatives , one of the equations in eq .1 can be dropped and from now on it is assumed that the second equation is dropped and only the following equation is used 2 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = p _ { 21 } ( x ) - p _ { 12 } ( x ) . is that the change in the share of a population supporting the first alternative is the difference between the rate of inflow into the first alternative and the outflow from it . the approximation ( 2 ) is considered in continuous time and solutions take values in the interval . however , for large n , the grid of states of the markov chain is very dense and , with a slight abuse of notation , the same notation is used for both .5 for any given k , it is simple to calculate the probabilities p ij ( x ) . however , for simplicity , it is assumed6 in this section that k = 3 . with this assumptionthe probability p 12 ( x ) reads 3 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 12 } ( x ) & = & x \\ left ( \\ alpha \\ left ( ( 1 - x ) ^ { 3 } + 3 ( 1 - x ) ^ { 2 } x \\ right ) \\ right . \\ \\ & & \\ left . + ( 1 - \\ alpha ) \\ left ( x ^ { 3 } + 3 ( 1 - x ) x ^ { 2 } \\ right ) \\ right ) \\ end { array } $ $ \\ end { document } p12 ( x ) = x ( 1x ) 3 + 3 ( 1x ) 2x + ( 1 ) x3 + 3 ( 1x ) x2and the probability p 21 ( x ) reads 4 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 21 } ( x ) & = & ( 1 - x ) \\ left ( \\ alpha \\ left ( x ^ { 3 } + 3 x ^ { 2 } ( 1 - x ) \\ right ) \\ right . \\ \\ & & \\ left . + ( 1 - \\ alpha ) \\ left ( ( 1 - x ) ^ { 3 } + 3 ( 1 - x ) ^ { 2 } x \\ right ) \\ right ) . \\ end { array } $ $ \\ end { document } p21 ( x ) = ( 1x ) x3 + 3x2 ( 1x ) + ( 1 ) ( 1x ) 3 + 3 ( 1x ) 2x . the probability p 12 is the product of two probabilities . they are the probability that the supporter of the first alternative is selected and the conditional probability that the second alternative is followed . the probability that the supporter of the first alternative is selected , given the state x of a population , is simply x. the conditional probability that the second alternative is followed is the sum of probabilities of four events : every individual in the reference group uses the second alternative and the majority follows what happens with the probability ( 1x ) ; two individuals in the reference group use the second alternative and the majority follows with the probability 3 ( 1x ) x ; only one individual in the reference group uses the second alternative and the minority follows with the probability ( 1 ) 3 ( 1x ) x ; and finally all individuals in the reference group use the first alternative and the minority follows with the probability ( 1 ) ( 1x ) . they are the probability that the supporter of the second alternative is selected and the conditional probability that the first alternative is followed . in the considered model , it is assumed that the probability of following a given alternative is independent of the currently supported alternative . thus , the conditional probability of following a given alternative is the same for both currently supported alternatives , i.e. the probabilities p 12 ( x ) and p 21 ( x ) differ only by the first term x and ( 1x ) , respectively , and switching every occurrence of to ( 1 ) and the other way around . ultimately , given the above assumptions , the differential equation describing the evolution of the share x ( t ) reads 5 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = f ( x ) = ( 1 - 2x ) \\ left ( x ^ { 2 } ( 2 \\ alpha -1 ) - x ( 2 \\ alpha -1 ) + 1 - \\ alpha \\ right ) . thus , for any initial conditions , there is a unique solution defined for t0 . second , the interval , which is a projection of the two - dimensional simplex , is forward invariant because f ( 0 ) = 10 and f ( 1 ) = 10 . for any follow - upprobability , there is an equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } = 1/2 $ \\ end { document } x ^ a = 1/2 and because \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { df ( \\ hat { x } ^ { a } ) } { dx } = \\ frac { 6 } { 2 } \\ left ( \\ alpha - \\ frac { 5 } { 6 } \\ right ) $ $ \\ end { document } df ( x ^ a ) dx = 6256this equilibrium is stable for 5/6 and unstable for 5/6 . for 5/6 , there are two additional equilibria , namely \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ hat { x } ^ { b } = \\ frac { 1 } { 2 } - \\ sqrt { \\ frac { 5 - 6 \\ alpha } { 4 ( 1 - 2 \\ alpha ) } } \\ quad \\ text { and } \\ quad \\ hat { x } ^ { c } = \\ frac { 1 } { 2 } + \\ sqrt { \\ frac { 5 - 6 \\ alpha } { 4 ( 1 - 2 \\ alpha ) } } . $ $ \\ end { document } x ^ b = 12564 ( 12 ) andx ^ c = 12 + 564 ( 12 ) . both equilibria are stable for 5/6 because \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { df ( \\ hat { x } ^ { b } ) } { dx } = \\ frac { df ( \\ hat { x } ^ { c } ) } { dx } = 5 - 6 \\ alpha 0 \\ quad \\ text { for } ~ ~ \\ alpha \\ frac { 5 } { 6 } .0 = 5/6 a pitchfork bifurcation occurs .7 figure 1 shows the behavior of f for various values of the follow - up probability and the bifurcation diagram for ( 5 ) . fig . 1 a behavior of f for various values of the follow - up probability . the dotted line is for = 9/12 , the solid bold line is for = 5/6 and the thin solid line is for = 11/12 . solid lines are for the stable equilibriums , the dotted line is for the unstable equilibrium a behavior of f for various values of the follow - up probability . the dotted line is for = 9/12 , the solid bold line is for = 5/6 and the thin solid line is for = 11/12 . solid lines are for the stable equilibriums , the dotted line is for the unstable equilibrium the analysis in the previous section is done for a small reference group where k = 3 . it is possible to derive exact formulas for p ij for any fixed k. however , the polynomials describing the probabilities of transitions become large and unwieldy very quickly . therefore , it is easier to approximate these probabilities by the central limit theorem . let l be the number of people supporting the first alternative in a randomly selected reference group of a size k ; l is a random variable following the binomial distribution with parameters k ( a number of trials ) ; and x is the probability of a success . let w denote the probability that l k / 2 , that is , w is the probability that the majority of individuals in the selected reference group supports the first alternative given the state of a population x. for large values of k , the probability w is approximated by the standard normal cumulative distribution function as follows 6 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } w & = & \\ text { pr } \\ left [ { l \\ frac { k } { 2 } } \\ right ] = 1 - \\ text { pr } \\ left [ { l \\ leq \\ frac { k } { 2 } } \\ right ] \\ \\ [ - 1 pt ] & = & 1 - \\ text { pr } \\ left [ { l - k x \\ leq \\ frac { k } { 2 } - kx } \\ right ] \\ \\ [ - 1 pt ] & = & 1 - \\ text { pr } \\ left [ { \\ frac { l - k x } { \\ sqrt { k x ( 1 - x ) } } \\ leq \\ frac { k / 2 - kx } { \\ sqrt { k x ( 1 - x ) } } } \\ right ] \\ \\ [ - 1 pt ] & \\ approx & 1 - { \\ phi } \\ left ( \\ frac { k / 2 - kx } { \\ sqrt { k x ( 1 - x ) } } \\ right ) \\ \\ [ - 1 pt ] & = & 1 - \\ frac { 1 } { 2 } \\ left [ 1 + \\ text { erf } \\ left ( { \\ frac { k / 2 - kx } { \\ sqrt { 2 k x ( 1 - x ) } } } \\ right ) \\ right ] , \\ end { array } $ $ \\ end { document } w = prl k2 = 1prlk2 = 1prlkxk2kx = 1prlkxkx ( 1x ) k / 2kxkx ( 1x ) 1k / 2kxkx ( 1x ) = 1121 + erfk / 2kx2kx ( 1x ) , where erf ( ) is the standard error function , given as \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ text { erf } ( { x } ) = \\ frac { 2 } { \\ sqrt { \\ pi } } { \\ int \\ limits _ { 0 } ^ { x } } \\ mathrm { e } ^ { - \\ tau ^ { 2 } } d \\ tau $ $ \\ end { document } erf ( x ) = 20xe2dand the approximation follows by the central limit theorem . the transition probabilities are 7 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 12 } ( x ) & = & x ( \\ alpha ( 1 - w ) + ( 1 - \\ alpha ) w ) \\ \\ p _ { 21 } ( x ) & = & ( 1 - x ) ( \\ alpha w + ( 1 - \\ alpha ) ( 1 - w ) ) . \\ end { array } $ $ \\ end { document } p12 ( x ) = x ( ( 1w ) + ( 1 ) w ) p21 ( x ) = ( 1x ) ( w + ( 1 ) ( 1w ) ) . taking into account ( 2 ) , ( 6 ) and ( 7 ) the equation analogous to eq .5 reads 8 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = g ( x ) = \\ left ( \\ frac { 1 } { 2 } - x \\ right ) + \\ left ( \\ alpha - \\ frac { 1 } { 2 } \\ right ) \\ text { erf } \\ left ( { \\ frac { \\ sqrt { k } } { 2 \\ sqrt { 2 } } \\ ; \\ frac { 2 x -1 } { \\ sqrt { x ( 1 - x ) } } } \\ right ) . however , the limits at these points are \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ lim \\ limits _ { x \\ to 0 ^ { + } } g ( x ) = 1 - \\ alpha 0 \\ qquad \\ text { and } \\ qquad \\ lim \\ limits _ { x \\ to 1 ^ { - } } g ( x ) = \\ alpha - 10 . these limits are taken as the values of g ( x ) for x = 0 and x = 1 . since g 0 and g 0 , the interval is forward invariant under g. also , g is a c function . thus , for any initial condition , there exists a unique solution defined for t0 . for any ( 0,1 ) , there is an equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ the derivative at x = 1/2 reads \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { d g ( x ) } { d x } = \\ frac { ( 2 \\ alpha -1 ) \\ sqrt { k } \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } } { 4 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 3/2 } } - 1 \\ quad \\ text { and } \\ quad \\ frac { d g ( 1/2 ) } { d x } = \\ sqrt { \\ frac { 2 } { \\ pi } } ( 2 \\ alpha -1 ) \\ sqrt { k } - 1 . further , dg ( 1/2 ) / dx = 0 for \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ alpha _ { 0 } = \\ frac { 1 } { 4 } \\ left ( \\ frac { \\ sqrt { 2 \\ pi } } { \\ sqrt { k } } +2 \\ right ) . 0 , the equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } $ \\ end { document } x ^ a is stable and , for 0 , the equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } $ \\ end { document } x ^ a is unstable . at 0 , the pitchfork bifurcation occurs .8 the behavior of a model for large reference groups is qualitatively identical to the simple model with k = 3 . however , the particular value of the critical follow - up probability 0 depends crucially on the size of a reference group . the larger the reference group , the smaller the critical follow - up probability 0 . eventually , for k , the critical follow - up probability would converge9 to 1/2 . figure 2a shows the behavior of g for various values of and k = 20 . figure 2b shows the dependence of 0 on the size of a reference group . fig . 2 a behavior of g for various values of the follow - up probability . the dotted line is for = 2/10 , the solid bold line is for = 0 and the thin solid line is for = 8/10 . b behavior of the critical follow - up probability 0 with respect to the cardinality of the reference group k a behavior of g for various values of the follow - up probability . the dotted line is for = 2/10 , the solid bold line is for = 0 and the thin solid line is for = 8/10 . b behavior of the critical follow - up probability 0 with respect to the cardinality of the reference group ka large but finite population of a size \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ n \\ in \\ mathbb { n } $ \\ end { document } n of individuals is assumed . at each period t = 0 , ,2 , , where 0 , there is a fraction of the population using the first brand . the learning algorithm employed by members of the population is very simple . at each period t , a single individual is selected at random .2 this individual randomly chooses a group of k persons from the population , referred to as the reference group .3 an individual in question determines which alternative is in the majority in a reference group and chooses this alternative with the probability ( 0,1 ) . the probability of following the majority in a reference group is called the follow - up probability . this process is repeated during every period . in the above construction , the time is assumed to be discrete , t = 0 , ,2 , , and the size of a population n is finite . the state of a population can be described in several different ways , but because the model is concerned only with the market share of each brand , it is described by the share of a population x ( t ) using the first brand . given that the size of a population n is finite , the set of possible states of a population { 0,1 / n ,2 / n , , ( n1 ) / n ,1 } is also finite . the procedure of brand selection defines the transition probabilities between the states of a population . these probabilities are denoted by p ij ( x ) , that is , p ij ( x ) is the probability that a single individual changes the brand from the i - th alternative to the j - th alternative , i , j = 1,2 , given the state of a population x. the above model is , in fact , a finite markov chain . this markov chain can be studied directly , but it is easier to consider a system of differential equations of the form 1 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left \\ { \\ begin { array } { llll } \\ hspace * { 1.5 pc } \\ dot { x } & = & p _ { 21 } ( x ) - p _ { 12 } ( x ) , \\ \\ . system ( 1 ) approximates4 the average behavior of the markov chain ; cf . ( 1 ) is derived by taking the limit n with = 1 / n but for the approximation to hold , it is enough to have the size n of a population finite and large enough . the size k of a reference group defines , together with the follow - up probability , the transition probabilities and is not related in any way to the size of a population but only to the state of a population , that is , as long as the state of a population is x and both k and are fixed , then the size n of a population can be arbitrary . it is assumed only that n is larger than k. in fact , in the context of the background story , it is better to think of k as a much smaller number than the size n of a population . it is clear that , for two alternatives , one of the equations in eq .1 can be dropped and from now on it is assumed that the second equation is dropped and only the following equation is used 2 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = p _ { 21 } ( x ) - p _ { 12 } ( x ) . is that the change in the share of a population supporting the first alternative is the difference between the rate of inflow into the first alternative and the outflow from it . the approximation ( 2 ) is considered in continuous time and solutions take values in the interval . however , for large n , the grid of states of the markov chain is very dense and , with a slight abuse of notation , the same notation is used for both .5 for any given k , it is simple to calculate the probabilities p ij ( x ) . however , for simplicity , it is assumed6 in this section that k = 3 . with this assumptionthe probability p 12 ( x ) reads 3 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 12 } ( x ) & = & x \\ left ( \\ alpha \\ left ( ( 1 - x ) ^ { 3 } + 3 ( 1 - x ) ^ { 2 } x \\ right ) \\ right . \\ \\ & & \\ left . + ( 1 - \\ alpha ) \\ left ( x ^ { 3 } + 3 ( 1 - x ) x ^ { 2 } \\ right ) \\ right ) \\ end { array } $ $ \\ end { document } p12 ( x ) = x ( 1x ) 3 + 3 ( 1x ) 2x + ( 1 ) x3 + 3 ( 1x ) x2and the probability p 21 ( x ) reads 4 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 21 } ( x ) & = & ( 1 - x ) \\ left ( \\ alpha \\ left ( x ^ { 3 } + 3 x ^ { 2 } ( 1 - x ) \\ right ) \\ right . \\ \\ & & \\ left . + ( 1 - \\ alpha ) \\ left ( ( 1 - x ) ^ { 3 } + 3 ( 1 - x ) ^ { 2 } x \\ right ) \\ right ) . \\ end { array } $ $ \\ end { document } p21 ( x ) = ( 1x ) x3 + 3x2 ( 1x ) + ( 1 ) ( 1x ) 3 + 3 ( 1x ) 2x . the probability p 12 is the product of two probabilities . they are the probability that the supporter of the first alternative is selected and the conditional probability that the second alternative is followed . the probability that the supporter of the first alternative is selected , given the state x of a population , is simply x. the conditional probability that the second alternative is followed is the sum of probabilities of four events : every individual in the reference group uses the second alternative and the majority follows what happens with the probability ( 1x ) ; two individuals in the reference group use the second alternative and the majority follows with the probability 3 ( 1x ) x ; only one individual in the reference group uses the second alternative and the minority follows with the probability ( 1 ) 3 ( 1x ) x ; and finally all individuals in the reference group use the first alternative and the minority follows with the probability ( 1 ) ( 1x ) . they are the probability that the supporter of the second alternative is selected and the conditional probability that the first alternative is followed . in the considered model , it is assumed that the probability of following a given alternative is independent of the currently supported alternative . thus , the conditional probability of following a given alternative is the same for both currently supported alternatives , i.e. the probabilities p 12 ( x ) and p 21 ( x ) differ only by the first term x and ( 1x ) , respectively , and switching every occurrence of to ( 1 ) and the other way around . ultimately , given the above assumptions , the differential equation describing the evolution of the share x ( t ) reads 5 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = f ( x ) = ( 1 - 2x ) \\ left ( x ^ { 2 } ( 2 \\ alpha -1 ) - x ( 2 \\ alpha -1 ) + 1 - \\ alpha \\ right ) . thus , for any initial conditions , there is a unique solution defined for t0 . second , the interval , which is a projection of the two - dimensional simplex , is forward invariant because f ( 0 ) = 10 and f ( 1 ) = 10 . for any follow - upprobability , there is an equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } = 1/2 $ \\ end { document } x ^ a = 1/2 and because \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { df ( \\ hat { x } ^ { a } ) } { dx } = \\ frac { 6 } { 2 } \\ left ( \\ alpha - \\ frac { 5 } { 6 } \\ right ) $ $ \\ end { document } df ( x ^ a ) dx = 6256this equilibrium is stable for 5/6 and unstable for 5/6 . for 5/6 , there are two additional equilibria , namely \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ hat { x } ^ { b } = \\ frac { 1 } { 2 } - \\ sqrt { \\ frac { 5 - 6 \\ alpha } { 4 ( 1 - 2 \\ alpha ) } } \\ quad \\ text { and } \\ quad \\ hat { x } ^ { c } = \\ frac { 1 } { 2 } + \\ sqrt { \\ frac { 5 - 6 \\ alpha } { 4 ( 1 - 2 \\ alpha ) } } . $ $ \\ end { document } x ^ b = 12564 ( 12 ) andx ^ c = 12 + 564 ( 12 ) . both equilibria are stable for 5/6 because \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { df ( \\ hat { x } ^ { b } ) } { dx } = \\ frac { df ( \\ hat { x } ^ { c } ) } { dx } = 5 - 6 \\ alpha 0 \\ quad \\ text { for } ~ ~ \\ alpha \\ frac { 5 } { 6 } .0 = 5/6 a pitchfork bifurcation occurs .7 figure 1 shows the behavior of f for various values of the follow - up probability and the bifurcation diagram for ( 5 ) . fig . 1 a behavior of f for various values of the follow - up probability . the dotted line is for = 9/12 , the solid bold line is for = 5/6 and the thin solid line is for = 11/12 . solid lines are for the stable equilibriums , the dotted line is for the unstable equilibrium a behavior of f for various values of the follow - up probability . the dotted line is for = 9/12 , the solid bold line is for = 5/6 and the thin solid line is for = 11/12 . solid lines are for the stable equilibriums , the dotted line is for the unstable equilibriumthe analysis in the previous section is done for a small reference group where k = 3 . it is possible to derive exact formulas for p ij for any fixed k. however , the polynomials describing the probabilities of transitions become large and unwieldy very quickly . therefore , it is easier to approximate these probabilities by the central limit theorem . let l be the number of people supporting the first alternative in a randomly selected reference group of a size k ; l is a random variable following the binomial distribution with parameters k ( a number of trials ) ; and x is the probability of a success . let w denote the probability that l k / 2 , that is , w is the probability that the majority of individuals in the selected reference group supports the first alternative given the state of a population x. for large values of k , the probability w is approximated by the standard normal cumulative distribution function as follows 6 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } w & = & \\ text { pr } \\ left [ { l \\ frac { k } { 2 } } \\ right ] = 1 - \\ text { pr } \\ left [ { l \\ leq \\ frac { k } { 2 } } \\ right ] \\ \\ [ - 1 pt ] & = & 1 - \\ text { pr } \\ left [ { l - k x \\ leq \\ frac { k } { 2 } - kx } \\ right ] \\ \\ [ - 1 pt ] & = & 1 - \\ text { pr } \\ left [ { \\ frac { l - k x } { \\ sqrt { k x ( 1 - x ) } } \\ leq \\ frac { k / 2 - kx } { \\ sqrt { k x ( 1 - x ) } } } \\ right ] \\ \\ [ - 1 pt ] & \\ approx & 1 - { \\ phi } \\ left ( \\ frac { k / 2 - kx } { \\ sqrt { k x ( 1 - x ) } } \\ right ) \\ \\ [ - 1 pt ] & = & 1 - \\ frac { 1 } { 2 } \\ left [ 1 + \\ text { erf } \\ left ( { \\ frac { k / 2 - kx } { \\ sqrt { 2 k x ( 1 - x ) } } } \\ right ) \\ right ] , \\ end { array } $ $ \\ end { document } w = prl k2 = 1prlk2 = 1prlkxk2kx = 1prlkxkx ( 1x ) k / 2kxkx ( 1x ) 1k / 2kxkx ( 1x ) = 1121 + erfk / 2kx2kx ( 1x ) , where erf ( ) is the standard error function , given as \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ text { erf } ( { x } ) = \\ frac { 2 } { \\ sqrt { \\ pi } } { \\ int \\ limits _ { 0 } ^ { x } } \\ mathrm { e } ^ { - \\ tau ^ { 2 } } d \\ tau $ $ \\ end { document } erf ( x ) = 20xe2dand the approximation follows by the central limit theorem . the transition probabilities are 7 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } p _ { 12 } ( x ) & = & x ( \\ alpha ( 1 - w ) + ( 1 - \\ alpha ) w ) \\ \\ p _ { 21 } ( x ) & = & ( 1 - x ) ( \\ alpha w + ( 1 - \\ alpha ) ( 1 - w ) ) . \\ end { array } $ $ \\ end { document } p12 ( x ) = x ( ( 1w ) + ( 1 ) w ) p21 ( x ) = ( 1x ) ( w + ( 1 ) ( 1w ) ) . taking into account ( 2 ) , ( 6 ) and ( 7 ) the equation analogous to eq .5 reads 8 \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = g ( x ) = \\ left ( \\ frac { 1 } { 2 } - x \\ right ) + \\ left ( \\ alpha - \\ frac { 1 } { 2 } \\ right ) \\ text { erf } \\ left ( { \\ frac { \\ sqrt { k } } { 2 \\ sqrt { 2 } } \\ ; \\ frac { 2 x -1 } { \\ sqrt { x ( 1 - x ) } } } \\ right ) . however , the limits at these points are \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ lim \\ limits _ { x \\ to 0 ^ { + } } g ( x ) = 1 - \\ alpha 0 \\ qquad \\ text { and } \\ qquad \\ lim \\ limits _ { x \\ to 1 ^ { - } } g ( x ) = \\ alpha - 10 . these limits are taken as the values of g ( x ) for x = 0 and x = 1 . since g 0 and g 0 , the interval is forward invariant under g. also , g is a c function . thus , for any initial condition , there exists a unique solution defined for t0 . for any ( 0,1 ) , there is an equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ the derivative at x = 1/2 reads \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ frac { d g ( x ) } { d x } = \\ frac { ( 2 \\ alpha -1 ) \\ sqrt { k } \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } } { 4 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 3/2 } } - 1 \\ quad \\ text { and } \\ quad \\ frac { d g ( 1/2 ) } { d x } = \\ sqrt { \\ frac { 2 } { \\ pi } } ( 2 \\ alpha -1 ) \\ sqrt { k } - 1 . further , dg ( 1/2 ) / dx = 0 for \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ alpha _ { 0 } = \\ frac { 1 } { 4 } \\ left ( \\ frac { \\ sqrt { 2 \\ pi } } { \\ sqrt { k } } +2 \\ right ) . 0 , the equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } $ \\ end { document } x ^ a is stable and , for 0 , the equilibrium \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ \\ hat { x } ^ { a } $ \\ end { document } x ^ a is unstable . at 0 , the pitchfork bifurcation occurs .8 the behavior of a model for large reference groups is qualitatively identical to the simple model with k = 3 . however , the particular value of the critical follow - up probability 0 depends crucially on the size of a reference group . the larger the reference group , the smaller the critical follow - up probability 0 . eventually , for k , the critical follow - up probability would converge9 to 1/2 . figure 2a shows the behavior of g for various values of and k = 20 . figure 2b shows the dependence of 0 on the size of a reference group . fig . 2 a behavior of g for various values of the follow - up probability . the dotted line is for = 2/10 , the solid bold line is for = 0 and the thin solid line is for = 8/10 . b behavior of the critical follow - up probability 0 with respect to the cardinality of the reference group k a behavior of g for various values of the follow - up probability . the dotted line is for = 2/10 , the solid bold line is for = 0 and the thin solid line is for = 8/10 . b behavior of the critical follow - up probability 0 with respect to the cardinality of the reference group kthe presented model is concerned solely with the isolated effect of the assumed algorithm of choosing a brand . as a result , any potential characteristics differentiating the brands are not part of the model and , consequently , the results are symmetric about the equal split of a market between two brands . the results of a model should be interpreted as the potential edge that one brand can have due only to the reference group influence and not the actual preferences of population s members , since those are absent from the model . the main result of the model is that this potential edge should be relatively small if the size of a reference group is small and the follow - up probability is not too large . this behavior results from the imprecise information from the reference group and is amplified if an individual is not certain how to act upon the information .5 and 8 , for k = 3 and k 3 , respectively , are only approximations to the actual markov chain .5 or 8 is ergodic for any ( 0,1 ) and so there is a unique stationary distribution depending on k and . this stationary distribution is symmetric about x = 1/2 . 0 , the stationary distribution is a single peak distribution . for 0 , the stationary distribution becomes a bimodal distribution with peaks aligned with the stable equilibria of a differential equation . as the value of a follow - up probability 1 , these peaks converge to 0 and 1 . for = 1the market share of the first brand fluctuates around x = 1/2 as long as 0 , with increasing variance for 0 . any realization of the markov chain spends most of the time near the stable equilibria of a differential equation , with occasional switches between them . the time spent near one of the equilibria depends on the size n of a population . the larger is n , the longer the time10 spent near the equilibrium before switching to the other equilibrium . the setup of the presented model is somewhat similar to other models , in particular to the models where the population is identified with the set of nodes of a graph and the reference group of a player ( node ) is then identified with the set of its neighbors , as in degroot ( 1974 ) , watts ( 2002 ) or acemoglu et al . ( the present model also can be fitted within this general setup , provided that the graph is the poisson graph11 with the average degree equal to the size of a reference group . in thisare usually referred to as the mean - field equations or the master equation ; cf . this is the typical choice for evolutionary game theory , population learning theory and other similar models such as the ones mentioned before . the compromise is the structure of a network of connections and the type of results ( average behavior ) that can be achieved . the random choice procedure used in the model can be thought of as reflecting an individual observing other randomly selected people and choosing a brand accordingly . there are other choices possible , e.g. the threshold rule used in watts ( 2002 ) , best - reply type rules or rules based on imitations . all these rules have one thing in common : they do not allow for innovations in the sense that , if all members of a population use the same brand , then every individual making the switch decision chooses the brand used by all members of a population .12 in terms of the markov chain , it means that these two states ( everyone uses the first brand and everyone uses the second brand ) are absorbing ( and consequently asymptotically stable equilibria ) . the concept of a reference group is used in the present paper in a very broad sense as introduced in section 1 . the speculations on the precise meaning of the presented model for theoretical sociology and economics is left for future research . it is , however , clear that , in the light of recent papers such as kramer et al . ( 2014 ) , it is important to try to understand if it is possible to construct and to provide a product that , through the manipulation of the follow - up probability , can swing the brand shares in favor of a particular brand . ultimately , the main insight from the presented model is the interplay between the precision of information and the strength of reaction to this information . if the information is not precise ( small k ) , then , even for a relatively strong reaction ( large ) , the result for the market share is slim ( realizations of the markov chain wander about x = 1/2 ) . it takes precise information and a strong reaction in a large population to influence the market share of a given brand for a longer time . whether this can be achieved in realityconsider the following differential equation \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ dot { x } = f ( x , \\ alpha ) , \\ quad x \\ in \\ mathbb { r } , \\ alpha \\ in \\ mathbb { r } . $ $ \\ end { document } x = f ( x , ) , x , . following ( wiggins 2003 , p. 372 ) , in order to show that the above equation undergoes a pitchfork bifurcation at \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ ( x , \\ alpha ) = ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) $ \\ end { document } ( x , ) = ( x ^ ,0 ) , it is sufficient to show that \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } f ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & 0 , \\ qquad \\ frac { \\ partial f } { \\ partial x } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) = 0 , \\ \\ \\ frac { \\ partial f } { \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & 0 , \\ qquad \\ frac { \\ partial ^ { 2 } f } { \\ partial x ^ { 2 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) = 0 , \\ \\ \\ frac { \\ partial ^ { 2 } f } { \\ partial x \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & \\ neq & 0 , \\ qquad \\ frac { \\ partial ^ { 3 } f } { \\ partial x ^ { 3 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) \\ neq 0 . we have \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ ( \\ hat { x } , \\ alpha _ { 0 } ) = ( 1/2 , 5/6 ) $ \\ end { document } ( x ^ ,0 ) = ( 1/2 ,5 / 6 ) and the following calculations \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } f ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & 0 , \\ \\ \\ frac { \\ partial f } { \\ partial x } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & ( 6 ( 1 - 2 \\ alpha ) ( x-1 ) x-1 ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial f } { \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & ( -4 x ^ { 3 } +6 x ^ { 2 } - 1 ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial ^ { 2 } f } { \\ partial x ^ { 2 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & ( -6 ( 2 \\ alpha -1 ) ( 2 x-1 ) ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial ^ { 2 } f } { \\ partial x \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & ( -12 ( x-1 ) x ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 3 \\ neq 0 , \\ \\ \\ frac { \\ partial ^ { 3 } f } { \\ partial x ^ { 3 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & ( 12 - 24 \\ alpha ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = - 8 \\ neq 0 . . 8 , we have \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ ( \\ hat { x } , \\ alpha _ { 0 } ) = \\ left ( 1/2 , \\ frac { 1 } { 4 } \\ left ( \\ frac { \\ sqrt { 2 \\ pi } } { \\ sqrt { k } } +2 \\ right ) \\ right ) $ $ \\ end { document } ( x ^ ,0 ) = 1/2 ,142 k +2 and the following calculations \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } g ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & 0 , \\ \\ \\ frac { \\ partial g } { \\ partial x } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & \\ left ( \\ frac { ( 2 \\ alpha -1 ) \\ sqrt { k } \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } } { 4 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 3/2 } } - 1 \\ right ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial g } { \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & \\ left ( \\ text { erf } \\ left ( \\ frac { \\ sqrt { k } ( 2 x-1 ) } { 2 \\ sqrt { 2 } \\ sqrt { - ( x-1 ) x } } \\ right ) \\ right ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial ^ { 2 } g } { \\ partial x ^ { 2 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & \\ left ( - \\ frac { ( 2 \\ alpha -1 ) \\ sqrt { k } ( 2 x-1 ) \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } ( k +12 ( x-1 ) x ) } { 32 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 7/2 } } \\ right ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 0 , \\ \\ \\ frac { \\ partial ^ { 2 } g } { \\ partial x \\ partial \\ alpha } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & \\ left ( \\ frac { \\ sqrt { k } \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } } { 2 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 3/2 } } \\ right ) | _ { ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) } = 2 \\ sqrt { \\ frac { 2 } { \\ pi } } \\ sqrt { k } \\ neq 0 , \\ \\ \\ frac { \\ partial ^ { 3 } g } { \\ partial x ^ { 3 } } ( \\ hat { x } ^ { } , \\ alpha _ { 0 } ) & = & \\ left ( \\ frac { ( 2 \\ alpha -1 ) \\ sqrt { k } \\ mathrm { e } ^ { \\ frac { k ( 1 - 2 x ) ^ { 2 } } { 8 ( x-1 ) x } } } { 256 \\ sqrt { 2 \\ pi } ( - ( x-1 ) x ) ^ { 11/2 } } h ( x , \\ alpha ) \\ right ) | _ { ( \\ hat { x } , \\ alpha _ { 0 } ) } = -4 ( k - 3 ) \\ neq 0 , \\ end { array } $ $ \\ end { document } g ( x ^ ,0 ) = 0 , gx ( x ^ ,0 ) = ( 21 ) kek ( 12x ) 28 ( x1 ) x42 ( ( x1 ) x ) 3/21 | ( x ^ ,0 ) = 0 , g ( x ^ ,0 ) = erfk ( 2x1 ) 22 ( x1 ) x | ( x ^ ,0 ) = 0,2 gx2 ( x ^ ,0 ) = ( 21 ) k ( 2x1 ) ek ( 12x ) 28 ( x1 ) x ( k +12 ( x1 ) x ) 322 ( ( x1 ) x ) 7/2 | ( x ^ ,0 ) = 0,2 gx ( x ^ ,0 ) = kek ( 12x ) 28 ( x1 ) x22 ( ( x1 ) x ) 3/2 | ( x ^ ,0 ) = 22k0 ,3 gx3 ( x ^ ,0 ) = ( 21 ) kek ( 12x ) 28 ( x1 ) x2562 ( ( x1 ) x ) 11 / 2h ( x , ) | ( x ^ ,0 ) = 4 ( k3 ) 0 , where \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { @ { } rcl @ { } } h ( x , \\ alpha ) & = & \\ left ( k ^ { 2 } ( 1 - 2 x ) ^ { 2 } +8 k ( x-1 ) ( 18 ( x-1 ) x +5 ) x \\ right . \\ \\ & & \\ left . + 48 ( x-1 ) ^ { 2 } ( 16 ( x-1 ) x +5 ) x ^ { 2 } \\ right ) . \\ end { array } $ $ \\ end { document } h ( x , ) = k2 ( 12x ) 2 + 8k ( x1 ) ( 18 ( x1 ) x +5 ) x +48 ( x1 ) 2 ( 16 ( x1 ) x +5 ) x2 .\noutput:\n" }, { "from": "agent", "value": "the present paper tries to answer analytically how much the reference group influence can affect an actual market share of a particular brand or product . it is found that the increase of the size of a reference group and the probability of following the majority within the reference group may lead to the temporary modest prevalence of one brand . this result requires a relatively large size of a reference group and a high probability of following the majority within the reference group . if these conditions are not satisfied the effect on the market share is negligible ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: sinusitis is reported to be one of the most widespread diseases in the united states and europe1 , 2 , 3 and is one of the most common reasons for patients to see a doctor or receive an antibiotic .1 , 4 , 5 although the disease may be less serious than other common diseases such as asthma or peptic ulcer disease , the cost of sinusitis care including associated emergency room ( er ) visits , medical specialist referrals , and work days missed exceeds the costs for both of those conditions .3 for such a common and costly condition , we lack valid epidemiologic data . methodological differences , imprecise terminology , and diagnostic inaccuracy all contribute to the data confusion . for example , provider diagnoses indicate that outpatient visits for chronic sinusitis ( cs ) substantially exceed those for acute sinusitis ( as ) , with a visit prevalence of 1.5 % for cs and 0.3 % for as .6 however , considering that as typically develops following a viral uri a condition that afflicts tens of millions of americans annuallythe selfreported patient prevalence of sinusitis is even less credible : 12 % to 16 % of patients report sinusitis each year ( as and cs combined ) .3 two recent studies highlight the inaccuracy of cs diagnosed by nonspecialty providers . by extensionhsu et al . used administrative data from a large academic institution to identify patients diagnosed with cs and performed a detailed review of the medical record to validate these diagnoses .7 they found that most cases of cs are never substantiated with imaging or endoscopy , and they ultimately concluded that cs diagnoses are unreliable unless they are confirmed by otolaryngologists or allergists . similarly began with administrative data from a large academic institution to identify patients diagnosed with cs by primary care and emergency medicine providers .8 the conducted a detailed review of the patients ' clinical presentation at the time of diagnosis , including patients ' signs , symptoms , endoscopic findings , and any computed tomography ( ct ) scan results . they found that most all diagnoses of cs made by primary care and emergency medicine providers are not substantiated by history at the time of diagnosis and that most cs diagnoses are never confirmed by specialty consultation , endoscopy , or imaging . given our lack of confidence in the validity of existing epidemiologic data , we designed a crosssectional pilot study to compare the visit prevalence of sinusitis diagnosed by primary care and emergency medicine providers between two cohorts : patients diagnosed at a representative academic institution and patients diagnosed in community medicine practices and private institutions . in order to make the study design comparable to prior reports ,6 , 9 , 10 , 11 , 12 , 13 we utilize national ambulatory medical care survey ( namcs ) , which is limited to ambulatory care clinics , and the national hospital ambulatory medical care survey ( nhamcs ) , which is mostly comprised of emergency department ( ed ) visits .14 , 15 we sought to improve the validity of the visit prevalence rates by using physiciancoded rather than patient selfreported diagnoses .3 we also sought to improve the specificity of the prevalence rates by analyzing cs and as separately . we hypothesized that the relative proportions of as and cs at our institution would be similar to national estimates . finally , as a control measure to validate our methods , we also chose to evaluate the prevalence of a very objective diagnosis : epistaxis . this study thus provides novel insights into the prevalence of sinusitis diagnoses made by primary care and emergency medicine provider at academic institutions , private institutions , and community medicine practices . for calculation of institutional visit prevalence , we identified adult ( age 18 years ) patients using the university of michigan health system ( umhs ) robust clinical research and health information exchange . the exchange contains demographic information ; inpatient and outpatient visits ; officebased , radiology , and surgical procedures ; and professional feebilling information . we compiled a census of all adult patients with one or more visits to either a primary care clinic or emergency medicine department between january 1 , 2005 , and december 31 , 2010 , and then calculated the total number of visits for sinusitis . primary care clinics included family medicine , general practice , internal medicine , general pediatrics , and internal medicine pediatrics clinics . we then identified the subset of patients seen for sinusitis using international classification of diseases , 9th revision ( icd9 ) codes ( icd9461.x for as , 473.x for cs ; both within first three diagnosis codes for each visit ) . we collected demographic information ( e.g. , age , gender , and race ) for all patients . to validate our methodology , we carried out the same process for epistaxis ( icd9784 .7 ) , a less subjective diagnosis . for calculation of a national visit prevalence estimate , we used namcs and nhamcs to identify adult ( age 18 years ) visits between january 1 , 2005 , and december 31 , 2010 , to nonfederal employed officebased physicians and to eds and outpatient departments of nontertiary care general and shortstay hospitals , respectively .14 , 15 because namcs and nhamcs are visitbased data sources , we identified sinusitis visits based on primary , secondary , or tertiary diagnoses of as or cs using icd9 codes ( icd9461.x , 473.x ) . namcs uses a threestage and nhamcs uses a fourstage probability sampling of nonfederal officebased and hospitalbased physicians , which is conducted annually by the u.s . national center for health statistics . sample data collected includes visitlevel information on demographic characteristics , comorbidities , up to three diagnoses ( one primary and two secondary diagnoses ) , procedures performed , radiographic studies ordered , and types of providers seen . for example , physician specialty codes allow for the identification of primary care physicians ( general or family medicine , internal medicine , and pediatrics ) in order to differentiate from medical specialists . patient visit weights are provided by the national center for health statistics .16 application of these weights in a multistage estimation procedure produces unbiased national estimates . we also compared the visit prevalence of epistaxis between our institution 's patient population and the national patient population . we chose to use patients with epistaxis as a control group because the diagnosis of epistaxis is less subjective than sinusitis and we had no a priori reason to think the rate of epistaxis would be different between the two study groups . this study was approved by the institutional review board at the university of michigan , ann arbor , michigan . annual descriptive statistics regarding demographic and clinical characteristics within the institution and nationally were calculated . the prevalence of sinusitis or epistaxis was defined as a ratio of the number of visits with a diagnosis of each disease by icd9 code to the total number of visits identified in that calendar year . we calculated prevalence separately for both as and cs based on icd9 codes listed above . visit weights provided by the national center for health statistics were applied , and we followed recommendations that estimates with a relative standard error 30 % , or estimates based on sample sizes of less than 30 observations , are considered unreliable . statistical analyses were performed using stata se 12 ( statacorp , college station , tx ) statistical software . for calculation of institutional visit prevalence , we identified adult ( age 18 years ) patients using the university of michigan health system ( umhs ) robust clinical research and health information exchange . the exchange contains demographic information ; inpatient and outpatient visits ; officebased , radiology , and surgical procedures ; and professional feebilling information . we compiled a census of all adult patients with one or more visits to either a primary care clinic or emergency medicine department between january 1 , 2005 , and december 31 , 2010 , and then calculated the total number of visits for sinusitis . primary care clinics included family medicine , general practice , internal medicine , general pediatrics , and internal medicine pediatrics clinics . we then identified the subset of patients seen for sinusitis using international classification of diseases , 9th revision ( icd9 ) codes ( icd9461.x for as , 473.x for cs ; both within first three diagnosis codes for each visit ) . we collected demographic information ( e.g. , age , gender , and race ) for all patients . to validate our methodology , we carried out the same process for epistaxis ( icd9784 .7 ) , a less subjective diagnosis . for calculation of a national visit prevalence estimate , we used namcs and nhamcs to identify adult ( age 18 years ) visits between january 1 , 2005 , and december 31 , 2010 , to nonfederal employed officebased physicians and to eds and outpatient departments of nontertiary care general and shortstay hospitals , respectively .14 , 15 because namcs and nhamcs are visitbased data sources , we identified sinusitis visits based on primary , secondary , or tertiary diagnoses of as or cs using icd9 codes ( icd9461.x , 473.x ) . namcs uses a threestage and nhamcs uses a fourstage probability sampling of nonfederal officebased and hospitalbased physicians , which is conducted annually by the u.s . national center for health statistics . sample data collected includes visitlevel information on demographic characteristics , comorbidities , up to three diagnoses ( one primary and two secondary diagnoses ) , procedures performed , radiographic studies ordered , and types of providers seen . for example , physician specialty codes allow for the identification of primary care physicians ( general or family medicine , internal medicine , and pediatrics ) in order to differentiate from medical specialists . patient visit weights are provided by the national center for health statistics .16 application of these weights in a multistage estimation procedure produces unbiased national estimates . we also compared the visit prevalence of epistaxis between our institution 's patient population and the national patient population . we chose to use patients with epistaxis as a control group because the diagnosis of epistaxis is less subjective than sinusitis and we had no a priori reason to think the rate of epistaxis would be different between the two study groups . this study was approved by the institutional review board at the university of michigan , ann arbor , michigan . annual descriptive statistics regarding demographic and clinical characteristics within the institution and nationally were calculated . the prevalence of sinusitis or epistaxis was defined as a ratio of the number of visits with a diagnosis of each disease by icd9 code to the total number of visits identified in that calendar year . we calculated prevalence separately for both as and cs based on icd9 codes listed above . visit weights provided by the national center for health statistics were applied , and we followed recommendations that estimates with a relative standard error 30 % , or estimates based on sample sizes of less than 30 observations , are considered unreliable . statistical analyses were performed using stata se 12 ( statacorp , college station , tx ) statistical software . during the 6 year study period of 2005 to 2010 , our institution had an annual average of 79,806 adult patients with at least one visit per year ( range 76,474 to 81,776 ) in primary care offices or hospital eds . there was an average of 3.8 visits per patient per year ( range 1 to 42 ) . during the corresponding period , namcs and nhamcs had an average of 962 million ambulatory care visits per year ( range 892 million to 1.03 billion ) ; patientlevel statistics are unavailable in this dataset . demographic analysis revealed a younger patient population at our institution ( mean 46.1 years , standard deviation 0.06 ) versus nationally ( mean 52.0 years , standard error 0.5 ) and comparable gender and race distributions ( table 1 ) . the distribution between primary care and er visits in each data set was also calculated . at our institution , primary care visits accounted for 76.0 % of visits for sinusitis , whereas ed visits accounted for 24.0 % . for namcs and nhamcs ,82.2 % of visits for sinusitis were to primary care providers , and 17.8 % were to an ed . university of michigan health system patientbased institutional cohort , reflecting entire patient population with no sampling error . namcs and nhamcs visitbased national cohort , reflecting sample of national visits with population weights applied . namcs = national ambulatory medical care survey ; nhamcs = national hospital ambulatory medical care survey ; sd = standard deviation ; se = standard error ; umhs = university of michigan health system . the prevalence of epistaxis , our control diagnosis , as a percentage of all patient visits was similar between the two datasets , with a range of 0.1 % to 0.2 % at our institution and a consistent 0.1 % nationally ( p = 0.980.99 ) ( table 2 ) . in contrast , the visit prevalence of sinusitis was substantially lower at our institution ( 0.7 % 1.0 % ) compared to national data ( 3.1 % 3.7 % ) ( p there were very small differences in prevalence of as between the two settings , with a difference of only 0.1 % to 0.5 % ( pin contrast , there were large differences in prevalence of cs between the two settings , with a difference of 1.6 % to 2.8 % ( p we explored regional variations in cs prevalence as a possible explanation for the reduced prevalence of cs at the umhs . we found the lower prevalence is not due to reduced prevalence of cs in the midwest , which would be reflected by the midwest cs prevalence in the namcs / nhamcs ( table 5 ) . proportion of adult ambulatory care visits for epistaxis comparing the umhsa with namcs / nhamcs national cohort.b university of michigan health system patientbased institutional cohort , reflecting entire patient population with no sampling error . namcs and nhamcs visitbased national cohort , reflecting sample of national visits with population weights applied . namcs = national ambulatory medical care survey ; nhamcs = national hospital ambulatory medical care survey ; sd = standard deviation ; se = standard error ; umhs = university of michigan health system . proportion of adult ambulatory care visits for sinusitis comparing the umhsa with namcs / nhamcs national cohort.b university of michigan health system patientbased institutional cohort , reflecting entire patient population with no sampling error . namcs and nhamcs visitbased national cohort , reflecting sample of national visits with population weights applied . namcs = national ambulatory medical care survey ; nhamcs = national hospital ambulatory medical care survey ; sd = standard deviation ; se = standard error ; umhs = university of michigan health system . proportion of adult ambulatory care visits for acute and chronic sinusitis comparing the umhsa with namcs / nhamcs national cohort.b university of michigan health system patientbased institutional cohort , reflecting entire patient population with no sampling error . namcs and the nhamcs visitbased national cohort , reflecting sample of national visits with population weights applied . ci = confidence interval ; namcs = national ambulatory medical care survey ; nhamcs = national hospital ambulatory medical care survey ; sd = standard deviation ; se = standard error ; umhs = university of michigan health system . proportion of adult ambulatory care visits for chronic sinusitis comparing the umhsa with four regions within namcs / nhamcs national cohort.b university of michigan health system patientbased institutional cohort , reflecting entire patient population with no sampling error national ambulatory medical care survey and the national hospital ambulatory medical care survey visitbased national cohort , reflecting sample of national visits with population weights applied namcs = national ambulatory medical care survey ; nhamcs = national hospital ambulatory medical care survey ; sd = standard deviation ; se = standard error ; umhs = university of michigan health system . in this study , we find our academic institution has a nearly 10fold lower prevalence of cs , as diagnosed by primary care and er providers compared to national estimates for the same geographic region . this large discrepancy was not found with the other conditions that we investigated as and epistaxis for which we found very similar prevalence estimates . the regional difference in cs across regions is too modest to account for the full magnitude of this discrepancy .10 the magnitude of the discrepancy in cs prevalence leads us to question the validity of national estimates of cs prevalence and burden of disease . chronic sinusitis is a difficult diagnosis with complex diagnostic criteria , and the condition must be differentiated from multiple other conditions with similar symptoms . otolaryngologists are experts in cs ; however , national estimates of cs prevalence and burden of disease are not based on expert diagnoses but on nonexpert diagnoses , often primary care and emergency medicine providers .6 , 10 , 11 , 17 these findings reflect the nature of the datasets that are used to study this problem . namcs and nhamcs are the most comprehensive datasets to study ambulatory care in the u.s . these surveys include a proportional sample of patient visits to all provider types , and statistical analysis allows one to make estimates about ambulatory care for the entire u.s . population . however , because there are fewer specialists than primary care providers , there are fewer patient visits to specialists in the datasets . accurate statistical analysis using this data relies on having sufficient number of patient visits in the dataset in order to make reliable estimates about the entire u.s . population . when there are relatively few patient visits to a particular provider type for a particular diagnosis , the types of research questions that can be answered is limited by statistical imprecision . we speculate that widely cited estimates of cs prevalence based on estimates from namcs and nhamcs are badly flawed by inaccurate diagnoses . this idea is supported by a recent longitudinal study of cs diagnoses , also using administrative data in community healthcare practices .18 the authors explored cs diagnoses and found that most diagnoses were never confirmed by endoscopy or ct . they further explored these diagnoses ( both confirmed and unconfirmed cases ) and found that , prior to a diagnosis of cs , many patients have visits for upper respiratory illness .18 the authors interpreted this association as evidence of the unified airway hypothesis . an alternative interpretation is that this association between frequent upper respiratory illness and diagnosis of cs reflects imprecise diagnosis of cs . providers may be assigning the diagnosis of cs to patients with recurrent or persistent uri symptoms without regard to cs diagnostic criteria . it is not clear why the prevalence of cs is so much lower at our academic institution compared to national data . it is possible that diagnoses of cs made within an academic institution are more accurate than diagnoses made in the community . in contrast , the diagnoses within our institution are made by a comparatively small cohort . physicians at academic centers may have more exposure to institutionally sponsored education that shapes their practice patterns . for example , our institution had an active effort prior to this study period to promote distinction between viral and bacterial sinusitis and judicious use of antibiotics . this institutional effort may have increased the diagnostic rigor , shaping diagnostic patterns locally in a way that the national sample of physicians included in namcs and nhamcs would not be affected . regional variation in cs prevalenceregional differences in cs visit prevalence have been reported namcs and nhamcs .6 , 10 data from those publications agree with the data we report in this study : the midwestern and southern regions have a higher prevalence of cs diagnoses than the northeastern and western regions . this consistently higher visit prevalence for cs in the midwest would not explain the lower prevalence we found at our midwestern academic institution . validation of cs diagnoses is a critically important factor that confounds sinusitis clinical research . although validation of diagnoses was beyond the scope of this pilot study , it was the focus of a recent study at our institution in which we attempted to validate new diagnoses of cs by primary care and emergency medicine providers .8 in that study , we compared each patient 's clinical characteristics to diagnostic criteria .5 we found that of all the patients given a new diagnosis of cs by a primary care or emergency medicine provider , less than 1 % of them met clinical diagnostic criteria .8 considering symptom duration alone , less than 10 % of patients had symptoms 12 weeks . very few patients were referred for endoscopy or had imaging ; of the few patients with imaging , many studies were normal or near normal . interestingly , we also found that in most patients with a coded diagnosis of cs , the provider 's clinical impression did not indicate cs , and the treatment plan was not consistent with cs . we concluded that nonotolaryngologists use the diagnostic code for cs without regard for the american academy of otolaryngology head and neck surgery 2015 definition of cs . we do not suggest that data from a single institution is indicative of the national disease prevalence . we acknowledge that , at our institution , the diagnostic accuracy of cs is very poor . however , the findings of this study as well as the study previously by novis8indicate that , at an institution where the rate of cs diagnosis is far lower than national norms , most patients still do not meet diagnostic criteria . taken together , they suggest the prevalence of cs may be significantly lower than national estimates from administrative data indicate . however , without better quality data , the true prevalence remains unknown . to our knowledge , the most rigorous study conducted to estimate cs prevalence across a population was a korean survey utilizing patient history and nasal endoscopy . this study demonstrated a 1 % population prevalence of sinusitis .19 although the population prevalence can not be directly compared to visit prevalence among patients seeking treatment , this study illustrates a rigorous methodological approach to address the question . the prevalence of cs in the united states is highly relevant to diagnostic and treatment recommendations . for example , a prior study suggested that for cs in the primary care setting , upfront ct is more costeffective than empiric medical therapy . based on what appears to be an extremely low pretest probability , we suggest instead that perhaps neither empiric medical therapy for cs nor upfront ct is appropriate for the majority of patients diagnosed with cs in this setting . it is critical that we understand these differences before we translate cs care from academic rhinology centers to the broader population of patients diagnosed with cs . further study of sinusitis in the community setting , as well as the education of primary care and emergency medicine providers , is needed before we encourage wide adaptation of intensive or expensive diagnostic or treatment protocols . first , the crosssectional design of the namcs and nhamcs datasets makes it impossible to determine if a visit for cs represents the initial diagnosis or a previously established diagnosis . to mitigate this limitation , we also used a crosssectional design when we created the academic dataset and did not differentiate between visits for the initial versus previously establish diagnosis of cs . second , it is also worth noting that we were unable to validate the accuracy of the diagnoses . epistaxis is a straightforward diagnosis presumably without substantial diagnostic variability , which is why we selected this as our control group . our finding that epistaxis rates were the same between the two datasets affirms that our analytic methods are valid . in contrast , sinusitis is a less straightforward diagnosis and presumably subject to greater diagnostic and coding variability , and a prior study demonstrated that administrative data are unreliable for identifying cases of cs .7 however , one of the important strengths of this study is the parallel study design . this is the first study to examine the prevalence of as and cs diagnosed by nonotolaryngologists at an academic institution . the prevalence of cs diagnosed by primary care and emergency medicine providers is much lower at our academic institution compared to national data , but the prevalence estimates of as and epistaxis are similar to national data . this finding suggests that across the country , where community healthcare settings outnumber academic institutions , cs is overdiagnosed . chronic sinusitis that is diagnosed outside of an academic institution or a specialty clinic may not hold up under diagnostic scrutiny in a specialty clinic . for this reason , diagnostic and treatment protocols for cs that have been developed in academic specialty clinics should not be extrapolated to patients diagnosed with cs in the community setting . education of primary care and emergency medicine providers and patients about conditions that may be misdiagnosed as cs may be the most appropriate treatment for the majority of patients diagnosed with cs in primary care and emergency medicine .\noutput:\n" }, { "from": "agent", "value": "objectiveto compare the prevalence of acute sinusitis ( as ) and chronic sinusitis ( cs ) diagnosed by primary care and emergency medicine physicians in our academic institution to national data.study designcrosssectional pilot study of institutional census data and a populationbased national sample . the setting was primary care and emergency departments at an academic healthcare institution and community healthcare practices nationally.materials and methodswe determined the proportion of adults visits at our institution for as and cs from january 1 , 2005 , to december 31 , 2010 . we used the same parameters with the national ambulatory medical care survey and the national hospital ambulatory medical care survey . as a control comparison , we determined the proportion of visits for epistaxis.resultsthe sinusitis prevalence was considerably lower at our academic institution : all sinusitis ( as and cs combined ) ranged from 0.8 % to 1.0 % at our institution compared to 3.1 % to 3.7 % nationally . there were very small differences between as rates at the academic institution ( 0.7 % 0.8 % ) and nationally ( 0.8 % 1.4 % , p < 0.001 ) but very large differences between cs rates at the academic institution ( 0.1 % ) and national data ( 1.7 % 2.9 % , p < 0.001 ) . epistaxis rates were nearly identical in both datasets ( 0.1 % 0.2 % , p = 0.980.99 ) . conclusionthe prevalence of cs is much lower at our academic institution , but the prevalence of as and epistaxis are similar to national data . this suggests cs is overdiagnosed by primary care and emergency medicine providers and that cs diagnosed outside of an academic institution or a specialty clinic may not hold up to diagnostic scrutiny . for this reason , diagnostic and treatment protocols for cs that have been developed in academic specialty clinics should not be extrapolated to patients diagnosed with cs in the community setting . the most appropriate intervention for the majority of patients diagnosed with cs in primary care and emergency medicine may be education of providers and patients about conditions that may be misdiagnosed as cs ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: in this study , 16 weeks old , 32 male albino rats of wistar strain , weighing 22020 g were used . laboratory animals prepared by ethical committee of ( protocol number ; 2011 - 01 ) . the rats were quarantined before irradiation , housed in individual stainless - steel cages in a pathogen - free environment in a windowless laboratory room with automatic temperature ( 223c ) and lighting controls ( 12 - h light / 12 - h dark ) and fed standard laboratory chow and water ad libitum . average light intensity was determined to be 4000 lux and humidity was 4010 % in the laboratory . the authors confirm adherence to the association for research in vision and ophthalmology ( arvo ) statement for the use of animals in ophthalmic and vision research . after one week adaptation process , the animals were randomized into four groups of eight rats each . the rats in group a1 ( cage control ) were not exposed to electromagnetic radiation ( emr ) or did not receive melatonin . the rats in group a2 ( sham control ) received an intraperitoneal injection of isotonic saline solution in the same volume and by the same scheme as that used in the group receiving melatonin without emr exposure . group b rats ( the emr group ) were exposed to 1 hour of emr from 9 am to 10 am for 30 days . group c rats ( treatment groups ) were exposed to emr in the same manner as group b and received melatonin treatment . melatonin was initially dissolved in 0.1 ml of dimethyl sulfoxide ( dmso ) and then diluted with physiological saline solution . melatonin was administered intraperitoneally at a dose of 10 g / kg and in a 0.1 ml volume of dmso . we used six rats in the exposure system in the same time [ fig . 1 ] . we used power values as 1 mw / m in the experiments as described below . a set eleco generator from set electronic co , istanbul ( turkey ) , provided with a half - wave dipole antenna system was used to irradiate the cells with a 2.45 ghz radio frequency with 217 hz pulses . the electric field density was set at 11 v / m in order to get a 0.1 w / kg whole - body average specific absorption rate ( sar ) and electromagnetic radiation values estimated for 2.45 ghz set up . the experimental setup for irradiation of rats the emr dose was calculated from the measured electric field density ( v / m ) . sar values were calculated by using electric properties of tissue sample and measured electric field intensities for every distance in certain frequency . the rats of group a2 were placed in the cylindrical restrainer with the radio frequency source switched off during times similar to those used for irradiation . the a1 control animals were kept in their cage without any treatment or restraint of any kind . head of all animals were cut and the lens samples were dissected as described in own previous study . the lens tissues were placed into glass bottles , labeled and stored in a deep freeze ( 33c ) until processing ( maximum 15 days ) . after weighing , the lens samples were placed on ice , and homogenized ( 2 minutes at 5000 rpm ) in a five volumes ( 1:5 , w / v ) of ice - cold tris - hcl buffer ( 50 mm , ph 7.4 ) , by using a glass ultrasonic homogenizer ( hd 2070 , bandelin ultrasonic homogenizer , bandelin electronics gmbh and co. kg , berlin , germany ) . the lens homogenate samples were used for immediate lipid peroxidation , gsh levels and enzyme activities . lipid peroxidation levels in the lens homogenate were spectrophotometrically ( at 532 nm ) measured with the thiobarbituric - acid reaction by the method of placer et al . the gsh content in the lens samples was spectrophotometrically measured at 412 nm using the method of sedlak and lindsay . gsh - px activities of the lens homogenate were measured spectrophotometrically at 37 c and 412 nm according to the lawrence and burk . the protein content in the lens homogenate was measured by method of lowry et al . all results are expressed as means standard deviation ( sd ) . to determine the effect of treatmentdata was analyzed using the statistical package for the social sciences software ( spss ) statistical program ( version 17.0 software , spss inc . in this study , 16 weeks old , 32 male albino rats of wistar strain , weighing 22020 g were used . laboratory animals prepared by ethical committee of ( protocol number ; 2011 - 01 ) . the rats were quarantined before irradiation , housed in individual stainless - steel cages in a pathogen - free environment in a windowless laboratory room with automatic temperature ( 223c ) and lighting controls ( 12 - h light / 12 - h dark ) and fed standard laboratory chow and water ad libitum . average light intensity was determined to be 4000 lux and humidity was 4010 % in the laboratory . the authors confirm adherence to the association for research in vision and ophthalmology ( arvo ) statement for the use of animals in ophthalmic and vision research . after one week adaptation process , the animals were randomized into four groups of eight rats each . the rats in group a1 ( cage control ) were not exposed to electromagnetic radiation ( emr ) or did not receive melatonin . the rats in group a2 ( sham control ) received an intraperitoneal injection of isotonic saline solution in the same volume and by the same scheme as that used in the group receiving melatonin without emr exposure . group b rats ( the emr group ) were exposed to 1 hour of emr from 9 am to 10 am for 30 days . group c rats ( treatment groups ) were exposed to emr in the same manner as group b and received melatonin treatment . melatonin was initially dissolved in 0.1 ml of dimethyl sulfoxide ( dmso ) and then diluted with physiological saline solution . melatonin was administered intraperitoneally at a dose of 10 g / kg and in a 0.1 ml volume of dmso . we used six rats in the exposure system in the same time [ fig . 1 ] . we used power values as 1 mw / m in the experiments as described below . a set eleco generator from set electronic co , istanbul ( turkey ) , provided with a half - wave dipole antenna system was used to irradiate the cells with a 2.45 ghz radio frequency with 217 hz pulses . the electric field density was set at 11 v / m in order to get a 0.1 w / kg whole - body average specific absorption rate ( sar ) and electromagnetic radiation values estimated for 2.45 ghz set up . the experimental setup for irradiation of rats the emr dose was calculated from the measured electric field density ( v / m ) . sar values were calculated by using electric properties of tissue sample and measured electric field intensities for every distance in certain frequency . the rats of group a2 were placed in the cylindrical restrainer with the radio frequency source switched off during times similar to those used for irradiation . the a1 control animals were kept in their cage without any treatment or restraint of any kind . head of all animals were cut and the lens samples were dissected as described in own previous study . the lens tissues were placed into glass bottles , labeled and stored in a deep freeze ( 33c ) until processing ( maximum 15 days ) . after weighing , the lens samples were placed on ice , and homogenized ( 2 minutes at 5000 rpm ) in a five volumes ( 1:5 , w / v ) of ice - cold tris - hcl buffer ( 50 mm , ph 7.4 ) , by using a glass ultrasonic homogenizer ( hd 2070 , bandelin ultrasonic homogenizer , bandelin electronics gmbh and co. kg , berlin , germany ) . the lens homogenate samples were used for immediate lipid peroxidation , gsh levels and enzyme activities . lipid peroxidation levels in the lens homogenate were spectrophotometrically ( at 532 nm ) measured with the thiobarbituric - acid reaction by the method of placer et al . the gsh content in the lens samples was spectrophotometrically measured at 412 nm using the method of sedlak and lindsay . gsh - px activities of the lens homogenate were measured spectrophotometrically at 37 c and 412 nm according to the lawrence and burk . the protein content in the lens homogenate was measured by method of lowry et al . , with bovine serumall results are expressed as means standard deviation ( sd ) . to determine the effect of treatmentdata was analyzed using the statistical package for the social sciences software ( spss ) statistical program ( version 17.0 software , spss inc . in this study , we found firstly in the literature that 2.45 ghz emr , to which people are intensely wi - fi exposed in daily life , increased malondialdehyde ( mda ) , the indicator of lipid peroxidation and oxidative stress on the lens , and decreased antioxidants including gsh level and gsh - px activity . oxidative stress and thus , ros , are believed to be a principal cause of noncongenital cataract . ros have been implicated in the development of lens opacification , which has been demonstrated in both experimental animal models and in cultured lens systems . ros including superoxide and singlet oxygen can also be generated in the lens and aqueous humor , which explains why areas of the world with higher intensity of emr irradiation have higher incidence of cataracts . mean values of cage control , sham control , wi - fi and wi - fi + melatonin groups as m / g protein were 10.8 , 10.7 , 11.4 and 9.8 , respectively . the lipid peroxidation levels were insignificantly higher in wi - fi group than in cage and sham control groups . however , lipid peroxidation levels were significantly ( p 0.05 ) lower in wi - fi + melatonin group than in wi - fi and control groups . the effects of melatonin on lipid peroxidation levels on lens of wi - fi - induced emr . ( mean sd ) . p 0.05 versus wi - fi and control groups levels of gsh are shown in [ fig . 3 ] . mean values of cage control , sham control , wi - fi and wi - fi + melatonin groups as m / g protein were 3.08 , 3.12 , 2.95 and 3.41 , respectively . however , gsh levels were significantly ( p 0.05 ) higher in wi - fi + melatonin group than in wi - fi group . the effects of melatonin on reduced glutathione ( gsh ) levels on lens of wi - fi - induced emr . ( mean sd ) . p 0.05 versus wi - fi group activities of gsh - px are shown in [ fig . 4 ] . mean values of cage control , sham control , wi - fi and wi - fi + melatonin groups as iu / g protein were 9.8 , 10.4 , 8.8 and 11.4 , respectively . the gsh - px activities were significantly ( p 0.05 ) lower in wi - fi group than in cage and sham control groups . the antioxidant enzyme activities were modulated by melatonin administration and their activities were significantly higher in wi - fi + melatonin group than in wi - fi ( p 0.01 ) and control groups ( p 0.05 ) . the effects of melatonin on reduced glutathione peroxidase ( gsh - px ) activities on lens of 2.45 ghz induced emr . ( mean sd ) . p 0.05 versus controls.p 0.01 versus wi - fi group gsh is the most prevalent low molecular weight thiol containing antioxidant within mammalian cells . the gsh acts to protect cellular constituents from oxidative damage by directly reacting with oxidants or as the substrate for gsh - px to scavenge peroxides . it is believed that the high content of gsh in the lens protects thiols in structural proteins and enzymes for proper biological functions . the endogenous high level of gsh plays a crucial role as the first line of defense against exogenous and endogenous ros and enables lens proteins to remain in a reduced state . the ros are continuously formed and are detoxified by superoxide dismutase , gsh - px and catalase . excessive production of free - radicals and the consumption of antioxidants lead to insufficient endogenous defense mechanisms . lipid peroxidation values as mda were increased in the lens samples by the wi - fi frequency exposure although gsh - px activity was decreased by the exposure . the gsh - px activity decreased in the lens samples because it may relate to the used antioxidants due to decrease ros production and the compensatory in the antioxidant redox system . melatonin , as well as its metabolites , act directly to detoxify ros such as hydroxyl radicals , peroxynitrite anion , singlet oxygen and reactive nitrogen species such as nitric oxide . melatonin possesses an electron - rich aromatic indole ring and acts as an electron - donor , thus having the ability to reduce and repair electrophilic radicals . in addition , melatonin stimulates antioxidant enzymes such as superoxide dismutase and gsh - px and they exert an antioxidative effect , indirectly . melatonin , as well as its metabolites , terminates the initiation and propagation of lipid peroxidation . melatonin is a stabilizer of cell membranes against oxidative stress . in the current study we observed gsh and gsh - px valueswere increased by melatonin administration although lipid peroxidation levels decreased due to its antioxidant protector effects and free radical scavenger effects . consistent with results of the current study , studies using ultraviolet radiation and ionize radiation as the oxidant agent , in which antioxidant efficacy of melatonin on the lens was demonstrated , reported that oxidant - antioxidant indicators were similarly affected . in conclusion , the results presented for wi - fi on lens are not consistent with a generalized antioxidant abnormality although melatonin induced modulator role on the over production of ros . the beneficial effects of melatonin on antioxidant systems included regulation of the lipid peroxidation , gsh - px and gsh values in the lens .\noutput:\n" }, { "from": "agent", "value": "introduction : melatonin has been considered a potent antioxidant that detoxifies a variety of reactive oxygen species in many pathophysiological states of eye . the present study was designed to determine the effects of wi - fi exposure on the lens oxidant , antioxidant redox systems , as well as the possible protective effects of melatonin on the lens injury induced by electromagnetic radiation ( emr ) . materials and methods : thirty - two rats were used in the current study and they were randomly divided into four equal groups as follows : first and second groups were cage - control and sham - control rats . rats in third group were exposed to wi - fi ( 2.45 ghz ) for duration of 60 min / day for 30 days . as in the third group , the fourth group was treated with melatonin . the one - hour exposure to irradiation in second , third and fourth took place at noon each day.results : lipid peroxidation levels in the lens were slightly higher in third ( wi - fi ) group than in cage and sham control groups although their concentrations were significantly ( p < 0.05 ) decreased by melatonin supplementation . glutathione peroxidase ( gsh - px ) activity was significantly ( p < 0.05 ) lower in wi - fi group than in cage and sham control groups although gsh - px ( p < 0.01 ) and reduced glutathione ( p < 0.05 ) values were significantly higher in wi - fi + melatonin group than in wi - fi group.conclusions : there are poor oxidative toxic effects of one hour of wi - fi exposure on the lens in the animals . however , melatonin supplementation in the lens seems to have protective effects on the oxidant system by modulation of gsh - px activity ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: tuberculosis ( tb ) is one of the leading infectious diseases , with a high morbidity and mortality worldwide ; approximately 8.6 million new cases and 1.3 million deaths are reported annually .1 the incidence of tb in south korea was 97 per 100,000 persons in 2010.1 the age - standardized incidence rate of gastric cancer is 59.3 persons and 23.5 persons per 100,000 male and female individuals , respectively .2 the co - existence of tb and cancer causes a diagnostic dilemma , as similarities in their presentations may lead to a delay in the appropriate therapy .3 in the current patient , a diagnosis of gastric cancer was established . however , the finding of peritoneal nodules , lymphadenopathy , ascites , and left pleural effusion with a suspicion of tb caused a treatment dilemma due to difficulties in making a differential diagnosis between advanced cancer with peritoneal carcinomatosis ( pc ) and tb pleurisy and peritonitis . the patient was a 39 - year - old married woman who presented to her local hospital with a history of abdominal pain and heartburn . physical examination revealed dullness with decreased air entry in the left lower chest and a soft abdomen with no rigidity or palpable masses . an upper gastrointestinal ( gi ) endoscopy revealed a 2 - cm ulcerative early gastric cancer in the antrum , with a biopsy result of signet ring cell carcinoma ( fig .1 ) . chest radiography and chest computed tomography ( ct ) revealed a left pleural effusion with pleural nodularity and lymphadenopathy ( fig .1 ) . an abdominal ct scan revealed diffuse peritoneal thickening , lymphadenopathy , a small amount of ascites , and nodular omental infiltration , suggesting a diagnosis of pc over that of tuberculous peritonitis ( tbp ) ( fig .2 ) . positron - emission tomography revealed left pleural and peritoneal hyper - metabolic lesions , most likely representing metastasis . thoracentesis revelaed a dominant lymphocytic exudate , with an adenosine deaminase ( ada ) level of 145.5 units / l , which was consistent with tb pleurisy . repeat thoracentesis with biopsy was performed ; the cytological analysis showed lymphocytic exudate , and the histology consisted of chronic inflammation with necrosis , suggesting tb pleurisy . the levels of the serum tumor markers cancer antigen ( ca ) 125 and ca 72 - 4 were 107 units / ml and 3 units / ml , respectively . her carcinoembryonic antigen ( cea ) level was 1.7 ng / ml . these findings , in addition to the gastroscopic diagnosis of early gastric cancer , raised the possibility of tbp rather than pc . we therefore decided to start anti - tb medication for 2 weeks initially , in order to avoid the active phase and infectivity of tb ; we then planned to compare the amount of pleural effusion and abdominal findings such as ascites , lymphadenopathy , and omental infiltration after this period . a follow - upct scan revealed increased pleural effusion and little improvement in the abdominal findings ( fig . the intraoperative macroscopic view was suggestive of tbp , and the frozen biopsy of several random peritoneal nodules showed chronic granulomatous inflammation ( fig .3 ) . hence , a laparoscopic distal gastrectomy with lymph node dissection was performed . the final pathological diagnosis was stage ia early gastric cancer according to the american joint committee on cancer staging system 7th edition ( sub - mucosal invasion and no metastasis in 26 harvested lymph nodes ) , and it was associated with chronic granulomatous inflammation and necrosis in the perigastric lymph nodes . the patient was discharged on postoperative day 7 on anti - tb medication and had an uneventful postoperative period . patients with malignant diseases are at an increased risk of tb . however , the association of tb with cancer could be coincidental or result from a secondary infection due to immunosuppression from chemo or radiotherapy . old age , male sex , previous anti - tb treatment , and gastrectomy are significant risk factors for tb .4 an increased risk of tb incidence after chemotherapy has been observed in patients with a history of tb .4 this is important , as tb involvement of the genitourinary or gi tract , peritoneum , lymph nodes or viscera constitutes up to 12 % of extra - pulmonary tb cases , and its nonspecific symptoms and signs may mimic gi or ovarian cancers .5 tbp is divided into three overlapping types : wet type ( the most common , ~ 90 % of cases ) , dry type , and fibrotic - fixed type . a diagnosis of adenocarcinoma with signet ring cells in a young woman is a risk factor for a poor prognosis .6 in our young female patient , signet ring cell gastric cancer with peritoneal thickening and nodules , lymphadenopathy , and ascites caused a diagnostic dilemma between pc and tbp , two diseases with completely different treatment pathways and prognoses . there are no pathognomonic clinical features or imaging findings that enable a definite diagnosis of tbp . clinical findings such as a duration of symptoms and fever of less than 1 month are helpful for differentiating tbp from pc .7 some authors suggest that polymerase chain reaction on the ascitic fluid obtained by ultrasound - guided fine needle aspiration is a relbiale method for tb diagnosis and should at least be attempted before surgical intervention .8 however , this was difficult in our case owing to minimal ascites . in addition to clinical and radiologic findings , an ascitic fluid ada measurement is also helpful in the differential diagnosis of tbp and pc .7 the role of tumor markers is not clear owing to a lack of specificity and sensitivity . in a previous study , theu tahors attempted to differentiate tbp from pc in 75 patients based on many parameters including tumor markers . they concluded that , in the absence of other systematic diseases , the presence of a fever , an elevated serum ca 125 level , and normal serum ca 19 - 9 and cea levels associated with predominantly benign ascites with lymphocytes may establish the diagnosis of tbp .7 in our patient , anti - tb medication was started 2 weeks before surgery for diagnostic purposes , based on the response to treatment ( an improvement of the peritoneal signs and the pleural effusion would indicate tb over pc ) , and to render the infective phase non - infective in the case of tb . we believe that laparoscopic exploration and histology on frozen sections may be the best approach for establishing the diagnosis and starting the appropriate treatment in such patients in the future . laparoscopy is the diagnostic tool of choice in patients with suspected tbp .9 co - existence of both tb and gastric cancer does not constitute a contraindication for anti - tb and anti - cancer chemotherapy , although chemotherapy was not indicated in our present case .10 in conclusion , the symptoms and signs of peritoneal tb are non - specific , and clinicians should adopt a high level of suspicion for peritoneal tb in patients who are febrile with the symptoms and signs of pulmonary tb , who have a history of tb , or who live in an area with a high incidence of tb . early diagnosis is critical for the management and prognosis of these patients , and there seems to be no contraindication for combined treatments .\noutput:\n" }, { "from": "agent", "value": "herein , we report a 39 - year - old female patient presenting with gastric cancer and tuberculous peritonitis . the differential diagnosis between advanced gastric cancer with peritoneal carcinomatosis and early gastric cancer with peritoneal tuberculosis ( tb ) , and the treatment of these two diseases , were challenging in this case . physicians should have a high index of suspicion for peritoneal tb if the patient has a history of this disease , especially in areas with a high incidence of tb , such as south korea . an early diagnosis is critical for patient management and prognosis . a surgical approach including tissue biopsy or laparoscopic exploration is recommended to confirm the diagnosis ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the central nervous system is often involved in patients with sle , and therefore , neuropsychiatric abnormalities are among the most common manifestations found in these patients . although various investigations including serological tests , cerebrospinal fluid analysis , electroencephalogram , and different neuroimaging techniques have been widely used to perform neurolo gical assessments in sle patients , it is still difficult to detect and manage the neurological abnormalities of these groups due to lack of useful diagnostic methods . in addition , it has been reported that sle patients may suffer from regional or general abnormal cortical blood flow even in the absence of neurological symptoms . cerebral blood flow ( cbf ) is regulated by changes in the arteriole resistance , which leads to arteriole dilation and constriction . given the importance of cbf , several imaging methods including positron emission tomography ( pet ) , single - photon emission computed tomography ( spect ) , and stable xenon - enhanced computed tomography have been employed to assess the compensatory response of cerebral autoregulation . however , all these methods are expensive and time - consuming . therefore , since 1982 , neurologists have been utilizing the transcranial doppler ( tcd ) as a safe , noninvasive , and low - cost technique , to study large intracranial vessels at the base of the skull , and to evaluate the cerebral blood flow . this method provides an assessment of different hemodynamic parameters such as flow velocity of intracranial arteries and cerebral vasomotor reactivity ( vmr ) . vasomotor reactivity is a hemodynamic parameter that represents the ability of the cerebral arterioles to dilate and constrict in response to specific stimuli . vmr is an important autoregulation mechanism that maintains cerebral blood flow . in patients with neurological involvements , this method can be helpful in the early diagnosis of some neurological abnormalities . in the light of the above , this study was designed to evaluate the vmr of the cerebral arteries of sle patients and compare it with that of normal subjects . after approval of the study by the ethics committee of the isfahan university of medical sciences and after obtaining informed consent , this comparative cross - sectional study was performed in the neurology outpatient clinic of al - zahra hospital , isfahan , iran , between march 2011 and april 2012 . on the basis of the reported influence of sex on vmr and a higher prevalence of sle among women , this study included only women . using the convenience sampling method , 60 stable female patients of age more than 18 years , with a diagnosis of sle ( according to the american college of rheumatology criteria ) , who were referred to the neurology outpatient clinic , entered the case group . the controls were 60 age - matched , healthy women selected from the hospital staff . the exclusion criteria were diabetes mellitus , hypertension , head injury , cerebrovascular disease ( transient ischemic attack , stroke , carotid artery stenosis more than 30 % , and intracranial stenosis demonstrated by cervical doppler sonography and tcd ) , chronic obstructive lung disease , hematological disease , and cancer . in addition , non - cooperative subjects and those treated with hormonal medications , beta - blocking agents , calcium channel blockers , nitrates , vasodilatory drugs , and anticoagulants were excluded . all subjects were asked to stop taking medications and smoking at least 12 hours prior to the tcd . a single neurologist who was unaware of the patients group performed tcd while the subjects were in the supine position with their eyes closed . all investigations were performed in the morning , using a dual 2 - mhz transducer , fitted on a headband . the trans - temporal window was used to insonate the middle cerebral artery ( mca ) . in the present study , vmr was calculated by measuring the changes in the mean flow velocity ( mfv ) of the mca induced by breath - holding . after a five - minute period of normal room air breathing , the rest mfv was recorded . next , the breath - holding mfv was recorded , after holding the breath for one minute . the breath holding index ( bhi ) was calculated from the following equation : the average of the bilateral bhi was considered as the subject bhi . there was no significant difference in the mean of the age between the two groups ( 31.767.50 years in the sle group vs. 32.434.55 years in the control group , p value : 0.64 ) . the mean duration of sle in the case group was 5.403.60 years ( minimum one year , maximum 16 years ) . within the sle group , 12 ( 20 % ) patients had nephritis , 32 ( 53 % ) patients had cutaneous manifestations , 34 ( 57 % ) patients had arthritis , four ( 7 % ) patients had seizure , two ( 3 % ) patients had cerebral vasculitis , and seven ( 12 % ) patients had thrombotic events . however , there was no significant difference in the bhi of patients with or without the aforementioned symptoms [ table 1 ] . systemic lupus erythematosus is an inflammatory disease that targets the vascular system and causes various vascular manifestations , such as , vasculitis , vasculopathy , vasospasm , thromboembolism , and premature atherosclerotic vascular disease . systemic lupus erythematosus patients may suffer from various primary and secondary conditions that can affect the vascular system and increase the risk of cerebrovascular problems . the primary causes include vasculitis , specific anti - neuronal antibodies , and lupus anticoagulant ; while renal disorders , hypertension , and steroid administration have been suggested as secondary causes . impairment of the vascular system may lead to disturbance in the cbf and cause neuropsychiatric abnormalities , which are common in sle patients . neuropsychiatric abnormalities are considered to be associated with either increased or decreased global and regional cerebral blood flow . cerebrovascular reactivity is considered to be an important hemodynamic parameter that represents adaptation potentialities of the cerebral circulation system , ability of the cerebral arteries to respond to changing conditions of functioning , and to optimize cbf in compliance with them . it has been reported that vascular risk factors can impair vmr , and consequently , increase the risk of cerebrovascular events . therefore , evaluation of vmr and vmr changes in clinical conditions that affect the vascular system can be helpful . to the best of our knowledge , this is the first study that has investigated the vmr of patients with sle , and compared it with the normal population . we have studied women with stable sle , compared them to an age - matched population of normal women , and found no significant difference between the two groups with regard to the average bhi of the mca . the value we have found for the bhi of the normal population is similar to the bhi reported by mousavi et al . for this sex and age group . however , there is no previous study that reports the bhi of the mca for sle patients . given the numerous factors that are considered to have adverse effects on the vascular system of sle patients , the question is why we have not found a significant difference in bhi between sle patients and the normal population . it is associated with the difference between the minimum and maximum diameter of the cerebral arteries , and depends on many factors , such as , age , gender , systemic hypertension , atherosclerosis , and other vascular diseases that affect the elasticity of the vessels . we have matched two groups with regard to sex and age , and selected stable patients according to the study criteria . a previous study by roman and colleagues has demonstrated that vascular changes in sle patients are time - dependent , and are significantly associated with the duration of the disease and duration of corticosteroid use . they have shown that sle patients with atherosclerotic plaques have average disease duration of 173 months , while it is 129 months in patients without atherosclerotic plaques . the average disease duration of our sle group was about five years ( 60 months ) , which is significantly lower than the proposed time required for atherosclerotic changes . therefore , it is not surprising that we did not find significant changes in the vmr of these patients . shorter disease duration is correlated with shorter duration of taking corticosteroids , which is another important factor that affects the vascular system . another factor contributing to this result is that we included stable sle patients , who had a low prevalence of neuropsychological abnormalities , and hence , they were not suffering from significant cerebrovascular problems . a major limitation of this study was the inability of some subjects to hold their breath for one minute , which led to exclusion of participants or a need for repetitive investigations . this problem could be solved by employing other techniques for stimulating hypercapnia such as using acetazolamide . this study indicated that vmr of women with stable sle was not significantly different from the age - and sex - matched normal population . however , we suggest further investigations on sle patients with longer disease duration , comparison of the vmr of patients with different sle durations with the normal population , and comparison of the vmr of sle patients with and without neuropsychological involvement , to provide a more reliable evaluation of the effects of sle on the vmr of cerebral arteries .\noutput:\n" }, { "from": "agent", "value": "background : neuropsychiatric abnormalities are among the most common manifestations of systemic lupus erythematosus ( sle ) . they have been proposed to be associated with impaired cerebral blood flow ( cbf ) . cerebral vasomotor reactivity ( vmr ) is a hemodynamic parameter effective in the autoregulation of cbf . the aim of the present study is to determine and compare the vmr of women with stable sle and normal women.materials and methods : according to the study criteria 60 women in each group entered the study . vmr was evaluated with transcranial doppler ( tcd ) at rest and after one minute of breath holding.results : there was no significant difference in the mean of age between two groups ( 31.76 7.50 years in the sle group versus 32.43 4.55 years in the control group , p value : 0.64 ) . the mean duration of sle in the case group was 5.40 3.60 years . the means of the breath - holding index ( bhi ) in the sle and control groups were 0.842 0.72 % and 0.815 0.26 % , respectively , which was not significantly different ( p value : 0.82 ) . conclusion : this study indicates that the vmr of women with stable sle is not significantly different from the age - and sex - matched normal population . however , further investigations on patients with longer sle duration and more neuropsychological abnormality rates are suggested ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the incidence of severe and invasive gas infection was significantly reduced in the early 20th century , however , since the late 1980s , there has been a resurgence of severe gas infections . a proposed theory for the resurgence of more serious gas related disease revolved around genetic shifts of m serotypes leading to gas species with greater virulence . gas is mainly transmitted through respiratory droplet spread , however , skin to skin transmission has also been described . it has rarely been reported to cause vulvovaginitis and pid in nonpregnant women . to the best of our knowledge , this is the first report describing an invasive gas infection of the pelvic organs in a menopausal woman that resulted in streptococcal toxic shock syndrome . a 55 year - old previously healthy woman presented with a one day history of rapidly progressive lower abdominal and pelvic pain . early on the day of admission , she felt well and actually went for a jog ; however , later that evening , she developed a crampy lower abdominal pain that progressed rapidly in intensity , radiating to the pelvis and lower back . the pain was associated with nausea , vomiting , malaise , generalized body aches , a severe headache , and subjective fever . her surgical history included an uncomplicated c - section 21 years ago and an uneventful iud removal six months ago . she exercised regularly , worked as a kindergarten teacher and has been recently exposed to children who had sore throats in the days preceding the onset of her symptoms . the patient has no history of sexually transmitted diseases and she denied wearing any sanitary products such as tampons . on admission , the patient appeared in moderate distress , was afebrile and her vital signs were within normal range . her abdomen was tender to palpation , especially over the lower quadrants , without peritoneal signs . the vaginal speculoscopy showed edematous and ecchymotic vaginal walls with small amount of dark blood in the cavity . the laboratory data showed a normal leukocyte count and a platelet count of 11110 / l . mmol / l and the anion gap was 15 consistent with an anion gap metabolic acidosis . an abdomen and pelvis ct scan showed predominately right - sided pelvic fluid collection without visualization of the appendix . a pelvic ultrasound revealed two mural uterine fibroids , the largest measuring 3 cm in diameter . the patient underwent a diagnostic laparoscopy , which revealed a completely necrotized right fallopian tube and ovary ( fig . post - surgery revealed a 2.5 cm 3 cm right cervix hematoma . she received empirical antibiotic therapy with vancomycin and piperacillin / tazobactam . on hospital day 2 , her condition deteriorated rapidly overnight ; she developed septic shock with multi - organ failure including disseminated intravascular coagulation ( dic ) . a subsequent examination revealed a small amount of vaginal bleeding and an ecchymotic cervix . the patient was taken again to the operating room because of the concern for progressing disseminated gas . the surgery revealed extensive necrosis of the pelvic organs , a total abdominal hysterectomy and a left salpingo - oophorectomy were performed . culture results of uterine and cervix tissue that were collected from the second surgery confirmed gas , therefore penicillin and clindamycin were started . on hospital day 3 , the patient returned to the operating room for a third time for a closure , during which the right infundibulopelvic ( ip ) ligament appeared necrotic and the gallbladder looked inflamed . the patient developed acute respiratory distress syndrome and remained on mechanical ventilation for seven days . acute pelvic inflammatory disease ( pid ) is usually caused by organisms ascending from the genital tract . gas is not a common organism in the vaginal flora thus an unusual cause of pid . with the resurgence of invasive gas infections since the mid-1980s , cases of intrapelvic infection in healthy non - pregnant pre - menopausal women have been reported . these cases have occurred in association with prior disease and procedures such as surgeries , skin infections , child birth or intrauterine devices , . traditionally , gas is mainly transmitted through respiratory droplets , although direct skin to skin transmission may occur . it rarely colonizes as a vaginal flora , carriers are usually asymptomatic . in a study of pregnant women , in the few reported cases of gas genital tract infection in non - pregnant women , it was hypothesized that the bacteria was inoculated from the person 's own pharynx or from a close contact source . while dermal or respiratory infection or carrier state serves as a likely source , sexual and hand contact increases the risk of genital - rectal inoculation , which presumably serves as a reservoir for ascending infection . mechanical disruption of the genital tract membrane by foreign bodies such as iud , instrumental or surgical procedures or child birth have been considered possible portals of entry for pelvic infection related with gas . less obviously menses and tampon use is reported as likely cause of ascending infection by gas . in menopausal women , the closest case related to this case was a 57 year old woman developed septic shock with dic who was found to have gas cervicitis during autopsy . prompt recognition with source control ( i.e. surgical removal of infected tissue ) and penicillin therapy are crucial to survival of invasive gas infection . in our patient , therefore it is recommended that high dose penicillin g and clindamycin be given in suspected invasive gas infection . in our case , steroid was also administered , considering severe stss can be associated with waterhouse friderichsen syndrome . most of the invasive female genital tract infections by gas were related with child birth , retained contraceptive product or sanitary products such as tampons , etc . we described a case of stss secondary to extensive intra - pelvic tissue necrosis caused by gas . we believe this case represents the first reported case of gas stss that results from rapidly spreading necrotizing inflammation of the genital tract in a previously healthy post menopausal woman . of particular interest , she has no obvious trauma , intrauterine foreign body or recent surgical procedure that can serve as a portal of entrance . the crucial steps that lead to her full recovery are prompt source control with surgical excision and diagnosis , early targeted antimicrobial regimen , as well as aggressive management of shock and multiorgan failure .\noutput:\n" }, { "from": "agent", "value": "group a - hemolytic streptococcus ( gas ) is well known to cause upper respiratory tract or cutaneous infections , but some more virulent species of gas can lead to a rapidly progressive life threatening soft tissue necrotizing infection and streptococcal toxic shock syndrome ( stss ) . in the modern era , gas infections within the female reproductive tract leading to stss are unusual and are often the result of retained products of conception or intrauterine devices . this report describes a case of gas necrotizing pelvic infection in a previously healthy menopausal woman with no obvious portal of entry . her clinical course rapidly progressed to septic shock and multiorgan failure . she required multiple surgeries in addition to targeted antimicrobials and aggressive management of shock and organ failures . after a prolonged hospital stay , she had a full recovery ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: splitting water into the fuel h2 and byproduct o2 using sunlight represents a sustainable strategy to produce renewable and storable energy . the design of solar water splitting systems remains an enormous challenge , and no commercial application of such technology exists despite extensive efforts over several decades . however , proof - of - principle water splitting has already been demonstrated by coupling a photovoltaic unit to a water electrolyzer , in photoelectrochemical ( pec ) cells , and colloidal systems . the intricate nature of the water oxidation half - reaction , involving multiple electron and proton transfers , is believed to be the main obstacle in achieving this goal . in addition , o2 has only limited commercial application and its production in complete water - splitting is potentially unwanted as most of the proton reduction catalysts are o2 sensitive , and system - damaging reactive oxygen species can form through incomplete water oxidation or from uncontrolled o2 reduction . replacing the water oxidation half - reaction with valuable substrate oxidation reactions would bypass o2 production and enable the synthesis of a high value organic chemical , a so - called solar chemical , in addition to the solar fuel h2 in a closed redox cycle . a useful process is the selective oxidation of benzyl alcohols to carbonyl compounds , which is a fundamental reaction both in the laboratory and on an industrial scale . for example , carbonyl derivatives such as aldehydes and ketones are widely used as precursors in the pharmaceutical and fragrance industries and for complex syntheses . sincemany classical oxidation reactions are currently carried out in organic solvents at high pressure and temperature and / or employ hazardous stoichiometric oxidants , such as mno4 or cro3 , there is clear scope for greener synthetic routes . simultaneous photoreduction of aqueous protons and organic substrate oxidation in a single compartment requires coupling between light harvester and catalysts , catalyzing two redox reactions , and the accumulation of products without their interference in the opposite half - reaction . to simplify this demanding task , the two halves of the system are typically studied separately with a sacrificial reagent closing the catalytic cycle . solar - light driven h2 production from water has been reported in the presence of sacrificial electron donors by employing solution based homogeneous and semiheterogeneous colloidal systems comprising a light harvester combined with synthetic , enzymatic , and metallic catalysts . photocatalytic oxidations of organic substrates containing alkene , amine , alcohol , and sulfide groups have also been reported in the presence of electron scavengers in homogeneous and suspension systems . molecular catalyst - driven simultaneous substrate oxidation and h2 production has been previously reported under fully homogeneous conditions as well as in pec cells . however , these reported nonsacrificial systems were carried out in organic solvents , employed multiple expensive and fragile noble metal based dyes and catalysts , leading to complicated schemes with low efficiencies , and thereby limited practical applications . there remains a need to find inexpensive and robust photosensitizers , which can couple proton reduction and substrate oxidation , while eliminating the need to consume noninnocent and unsustainable sacrificial reagents . a promising photocatalytic material is a polyheptazine - based carbon nitride , as it is nontoxic , metal - free , and easily synthesized from inexpensive precursors and shows thermal and chemical stability . the well positioned band edges also make it feasible to drive many photocatalytic reactions , including full water splitting . polymeric carbon nitride has been applied for photocatalytic h2 evolution in the presence of metallic and molecular catalysts . mesoporous carbon nitride has also been reported to act as a photocatalyst for mild radical oxidation of benzyl alcohols , without the need for an oxidation catalyst , under an o2 ( via o2 ) saturated environment as a sacrificial electron acceptor , in organic solvents . herein , we report a complete redox cycle that photocatalyzes the production of h2 coupled to the selective oxidation of benzyl alcohols to aldehydes . as a light harvester , we employed a carbon nitride with a cyanamide surface functionalization notated as cnx ( figure 1 ) , which has been recently reported to be significantly more active for h2 production than the unfunctionalized carbon nitride , cnx , under sacrificial conditions . to enable platinum - free conditions , we employed a molecular nickel ( ii ) bis ( diphosphine ) based h2 - evolution catalyst , nip ( figure 1 ) , and the cnx nip system allowed for visible - light driven benzyl alcohol oxidation and simultaneous h2 production in purely aqueous solution at room temperature and ambient pressure , in the absence of organic cosolvents and sacrificial reagents ( figure 1 ) . schematic representation of a closed redox system for solar - driven simultaneous proton reduction and alcohol oxidation in aqueous solution . irradiation of surface functionalized carbon nitride , cnx , results in the formation of a photoexcited state in which the holes are quenched by alcohol for aldehyde formation and the photoexcited electrons are effectively transferred from cnx to the molecular catalyst nip ( bromide counterions omitted for clarity ) resulting in h2 formation . we have previously reported a platinum - free sacrificial h2 evolution system with cnx and the molecular ni catalyst , nip . amorphous polymeric cnx , known as melon , is a metal - free photocatalyst , which can be easily synthesized from nitrogen rich precursors , and it displays long - term activity and stability.nip belongs to a family of hydrogenase - inspired molecular catalysts with a ni - bis ( diphosphine ) catalytic core , and it has been shown to operate effectively in heterogeneous hybrid systems , as well as under homogeneous conditions . here , we have used the more active cnx ( for characterization see figures s1s3 ) , to investigate full redox cycle systems for solar light driven simultaneous alcohol oxidation and proton reduction ( figure 1 ) . photocatalytic systems were prepared by dispersing cnx ( 5 mg ) , nip , and 4 - methylbenzyl alcohol ( 4 - mba ) in an aqueous phosphate ( kpi ) solution ( 3 ml ) , in a photoreactor with a total volume of 7.74 ml . the photoreactor was sealed with a rubber septum , purged with n2 ( containing 2 % ch4 ) , and then irradiated at 25 c using a solar light simulator equipped with an air mass 1.5 global ( am 1.5 g ) filter at 1 sun intensity ( 100 mw cm ) , unless specified otherwise . the headspace h2 gas was quantified in regular intervals by gas chromatography ( using ch4 as internal standard ) , while 4 - mba and other possible oxidation products were analyzed by h nmr spectroscopy ( see experimental section for details ) . the conversion yield was determined based on the percentage conversion of benzyl alcohol to oxidation products ( figure s4 ) . the reaction conditions were optimized systematically for h2 production activity per catalyst , expressed as nip - based turnover frequency ( tofnip ; mol h2 ( mol nip ) h determined after 1 h of irradiation ) and turnover number ( tonnip ; mol h2 ( mol nip ) determined after 24 h of irradiation , unless specified otherwise ) , as well as the conversion yield and selectivity of alcohol conversion to oxidation products after 24 h. the parameters of optimization were the amount of nip , the amount of 4 - mba , and the ph of the solution ( table s1 , figures s5s8 ) . the optimized conditions for the cnx nip system are 5 mg of cnx suspended in 3 ml of kpi ( 0.02 m , ph 4.5 ) with 50 nmol of nip and 30 mol of 4 - mba under simulated solar light irradiation ( figure 2 ) . there was a linear increase in both h2 and aldehyde production for the first 6 h of irradiation , whereupon the rate started to decrease over time ( table s2 ) . a tofnip of 31.13.1 h and tonnip of 425.442.5 was achieved with full solar spectrum irradiation , while oxidation of 4 - mba afforded 4 - methylbenzaldehyde ( 4 - mbad ) selectively in 66.06.6 % yield without further oxidation to form the carboxylic acid . thus , h2 and 4 - mbad were photogenerated cleanly and in a 1:1 stoichiometry over time and reached 21.32.1 mol and 19.82.0 mol after 24 h , respectively ( figure 2a ) . ( a ) time - dependent photocatalytic aldehyde and h2 production with cnx ( 5 mg ) , nip ( 50 nmol ) , 4 - mba ( 30 mol ) in kpi ( 0.02 m , ph 4.5 , 3 ml ) under 1 sun irradiation ( am 1.5 g ) at 25 c . for each time - point , three vials were irradiated for a specified number of hours and then worked - up . ( b ) simultaneous h2 and aldehyde production under optimized reaction conditions in the absence ( am 1.5 g ) and in the presence of a uv - filter ( 400 nm ) . the pair of hollow and filled symbols of the same shape and color corresponds to h2 and aldehyde production , respectively , under the specified reaction conditions . control experiments in the absence of nip , 4 - mba , cnx and in the dark are also shown . control experiments in the dark or in the absence of cnx did not yield h2 or aldehyde ( table s3 ) . in the absence of nip , only negligible amounts of h2 were detected during irradiation , but selective 4 - mba oxidation to 4 - mbadwas observed with a 24.32.4 % conversion , suggesting that 4 - mba oxidation may be the first step in the catalytic redox cycle ( see below for more details ) . in the absence of 4 - mbanip photosystem was also studied under visible only irradiation ( 400 nm ) . a tofnip of 12.31.2 h and a tonnip of 206.324.1 were observed , with 33.76.5 % 4 - mba conversion , corresponding to approximately 50 % of the activity observed under full spectrum irradiation ( figure 2b ) . the visible light response of the cnx nip system showed improvement when compared to the previously reported sacrificial cnxnip photosystem , where only 16 % of the activity observed under full spectrum irradiation was preserved under visible - light irradiation . the activity of nip in this closed redox cycle compares well with previously reported sacrificial h2 production hybrid systems using colloidal light absorbers . a photocatalytic system comprising cnx and nip in sacrificial electron donor ethylenediaminetetraacetic acid ( edta ) solution at ph 4.5 resulted in a tofnip of 109.310.9 h and tonnip of 155 . sacrificial photo - h2 generation was also demonstrated with nip and ruthenium tris ( bipyridine ) ( rup ) dye sensitized tio2 , which showed a tofnip of 725 h and tonnip of 27819 . more recently , carbon quantum dots were used as a photosensitizer in a sacrificial system with nip , and a tofnip of 41 h and tonnip of 64 were reported . the external quantum efficiency ( eqe ) of the system was determined using a solar light simulator equipped with a monochromator ( = 36010 nm , i = 4.43 mw cm ) . the highest eqe of 15.21.5 % was obtained with cnx ( 5 mg ) , 4 - mba ( 30 mol ) in 3 ml of kpi ( 0.1 m ) buffer at ph 4.5 after 1 h of irradiation . nip hybrid system with an eqe of 0.370.02 % , as well as the homogeneous rup nip system with an eqe of 9.71.2 % . the activity of cnx for benzyl alcohol oxidation also compares well with systems reported for substrate oxidation with a sacrificial electron acceptor . photocatalytic 4 - mba oxidation in the presence of a carbon nitride , under a high pressure of o2 , resulted in 77 % 4 - mbad formation with 99 % selectivity , but the oxidation was carried out in fluorinated organic solvent to promote o2 solubility and at 100 c . another system with carbon nitride and o2 as a sacrificial acceptor reported 59 % 4 - mba oxidation with 66 % selectivity for 4 - mbad in water , but required 100 c and strongly acidic conditions ( ph 0 ) . the cnx provides a platform for selective benzyl alcohol oxidation , whereas substrate oxidation reactions on metal oxides such as tio2 are limited by low selectivity due to formation of highly oxidizing holes and reactive radicals in water . nip colloidal suspension system reported in this work combines selective substrate oxidation and h2 production in a single compartment , thereby eliminating the need for a sacrificial reagent , remaining functional under fully aqueous solution and at room temperature as well as ambient pressure for up to 24 h. a series of benzyl alcohols with different para - substituents were studied to probe the effect of substrate structure on photocatalytic performance ( table s3 ) . conversion yields observed did not show a direct correlation with respect to the electron - donating or - withdrawing nature of the substituents . only withthe strongest electron - withdrawing substituent tested , cf3 , was a significant reduction in conversion yield to 6.12.0 % observed . all of the benzyl alcohol derivatives underwent selective conversion to the aldehyde , except for with the strongest electron - donating group , c ( ch3 ) 3 , in which 64 % selectivity for aldehyde formation was observed and further oxidation to 4 - tert - butylbenzoic acid also occurred . the results indicate that alcohol oxidation is not the overall activity - limiting step in the redox cycle ( see below ) . when 4 - mba ( 30 mol ) was replaced with methanol ( 30 mol ) under otherwise identical conditions ( cnx and nip in kpi ) , no h2 was observed , in contrast to systems using an excess amount of aliphatic alcohols as a sacrificial reagent for photocatalytic proton reduction . replacing the phosphate with acetate buffer ( ph 4.5 , 0.1 m ) did not alter the photocatalytic rate of h2 and aldehyde generation during the first few hours , indicating that the activity of the cnx nip system is not significantly buffer dependent , although the photoactivity decayed faster in the acetate buffered system ( table s4 ) . increasing the phosphate concentration from 20 mm to 0.1 and 0.5 m led to an enhancement in initial activity from tofnip = 31.13.1 to 76.37.6 and 111.411.1 h , respectively . however , after 24 h , the system performances equalized with a tonnip of approximately 400 and a 4 - mba - to -4-mbad conversion yield between 60 % to 83 % observed for the three systems ( tables s1 and s4 ) . further experiments in 20 mm kpi solution with 80 mm kcl or 80 mm k2so4 showed a slight increase in the photocatalytic rate of h2 production with a tofnip of 53.95.9 and tofnip of 49.24.9 h , respectively ( figure s9 ) . these results suggest that the enhanced photocatalytic activity is partially due to the ionic strength of the buffer used but also the significant increase in phosphate ion concentration that can potentially act as a proton relay , improving the efficiency of proton transfer to the molecular catalyst . the efficiencies of the individual half - reactions of the photocatalytic system were also examined separately in sacrificial schemes ( figure 3 ) . solar - light - driven h2 production was tested with cnx ( 5 mg ) and nip ( 50 nmol ) in aqueous edta electron donor solution at ph 4.5 , in the absence of 4 - mba . a tofnip of 53.25.3 h and a tonnip of 424.1842.4 were recorded in edta solution , similar to the 4 - mba system , suggesting that the cnxnip hybrid system is not limited by the electron donation of 4 - mba in the longer time regime ( table s4 ) . photocatalytic h2 production and 4 - mba oxidation in the presence of cnx ( 5 mg ) , 4 - mba ( 30 mol ) , and nip ( 50 nmol ) in an aqueous kpi solution ( 0.02 m , ph 4.5 , 3 ml ) . sacrificial h2 production with cnx ( 5 mg ) and nip ( 50 nmol ) in edta ( 0.1 m , ph 4.5 , 3 ml ) in the absence of 4 - mba . sacrificial alcohol oxidation with cnx ( 5 mg ) and 4 - mba ( 30 mol ) in an aqueous kpi solution ( 0.02 m , ph 4.5 , 3 ml ) under air , as a sacrificial electron acceptor , in the absence of nip . all samples were irradiated with 1 sun irradiation ( 100 mw cm , am 1.5 g , 25 c ) . the pair of hollow and filled symbols of the same shape and color corresponds to h2 and aldehyde production , respectively , under the specified reaction conditions . the ability of the system to carry out alcohol oxidation was investigated by replacing the molecular catalyst nip with air ( o2 ) as an electron acceptor . solar - light driven alcohol oxidation with cnx ( 5 mg ) and 4 - mba ( 30 mol ) resulted in quantitative alcohol oxidation with 70 % selectivity toward 4 - methylbenzoic acid formation after 24 h , with respect to the products detected by h nmr ( table s4 ) . this implies that the degree of oxidation of alcohols with this material can be tuned by varying the nature of the electron acceptor and demonstrates an advantage of using nip over the sacrificial acceptor o2 . the ability of o2 to act as an electron acceptor in this system also highlights a key advantage of substrate oxidation over full water splitting in one - pot systems , where the o2 formed would compete with and inhibit proton reduction . the photocatalytic activity of cnxnip was compared with conventional unfunctionalized melon - type carbon nitride , cnx ( figures 4 and s10 ) . nip under the same experimental conditions ( tofnip = 11.71.2 h and tonnip = 49.7914.2 ; table s5 ) , indicating that surface functionalization of the carbon nitride is vital . the enhanced photocatalytic activity of cnx compared to cnx has been previously attributed to the improved interaction and charge transfer via the cyanamide moieties of the cnx and a pt catalyst . we demonstrate here that this enhanced activity with cnx is also observed when the pt was replaced with the molecular nip catalyst . photocatalytic h2 and aldehyde production with cnx or cnx ( 5 mg ) , in the presence of 4 - mba ( 30 mol ) and nip ( 50 nmol ) in kpi ( 0.02 m , ph 4.5 , 3 ml ) were conducted under 1 sun irradiation ( 100 mw cm , am 1.5 g , 25 c ) . photocatalytic experiments in the presence of cnx or cnx ( 5 mg ) , 4 - mba ( 30 mol ) , and h2ptcl6 ( 10 l , 8 wt % ) in kpi ( 0.02 m , ph 4.5 , 3 ml ) were also carried out . the pair of hollow and filled symbols of the same shape and color corresponds to h2 and aldehyde production , respectively , under the specified reaction conditions . the in situ photodeposition of h2ptcl6 to platinize cnx or cnx was carried out following an optimized pt loading procedure , resulting in the formation of cnx pt and cnx pt systems for photo - h2 generation . these systems were then studied for simultaneous alcohol oxidation and proton reduction ( figure 4 , table s5 ) in the absence of nip under otherwise identical conditions . nip toward h2 production during the initial 4 h of irradiation , whereas cnxboth cnx pt and cnx pt showed only approximately 5 % 4 - mba oxidation to aldehyde after 4 h of irradiation . the initially low photocatalytic activity of pt could be attributed to an induction period associated with the photodeposition of the active catalyst . even after 24 h of irradiation , the overall photocatalytic activity of cnx nip ( h2 : 4 - mbad = 21:20 mol ) was still better than that with cnx pt ( 14:12 mol ) , representing the clear advantage of the molecular ni catalysts over pt in this system . a similar trend was previously reported with a sacrificial system containing carbon quantum dots and nip . a control experiment was carried out to confirm that pt does not interfere with the 4 - mbad formed by the oxidation of 4 - mba . in sacrificial edta solution , cnx pt and 4 - mbad ( 30 mol ) were combined in the absence of nip ( table s5 ) . after 24 h of irradiation , 18 % of the 4 - mbad was oxidized to carboxylic acid , whereas 4 - mba was not detected by h nmr spectroscopy , indicating that pt is not able to reduce 4 - mbad to 4 - mba , but may also act as unselective catalyst for 4 - mbad oxidation . to gain better insights into the rate - limiting factors of the cnxnip hybrid system , the amounts of nip , 4 - mba , and light intensity were varied . doubling the amount of nip from 50 to 100 nmol per 5 mg of cnx or the amount of 4 - mba from 30 to 60 mol did not result in a significant change in photoactivity ( table s1 ) . however , reducing the light intensity by 50 % and 80 % using neutral density filters resulted in an approximately 40 % and 85 % reduction in photocatalytic activity for h2 and 4 - mbad production after 1 h of irradiation ( table s6 , figure s11 ) . the activity is therefore proportional and linearly dependent on the light intensity , which is also consistent with the reduced photoactivity of cnx nip when filtering the uv light from the solar spectrum ( see above ) . the stability - limiting component of the system was identified by reactivation of a cnx - nip system after 25 h of irradiation ( table s7 ) . readdition of 4 - mba ( 30 mol ) did not reactivate the system , whereas addition of fresh nip ( 50 nmol ) restored solar - h2 production and enhanced the conversion yield for selective 4 - mba oxidation to 83.59.7 % ( figure s12 ) . therefore , the selectivity toward aldehyde formation is preserved despite the longer irradiation period ( 50 h ) , while the lifetime of the system is limited by the degradation of nip . x - ray photoelectron spectroscopy ( xps ) and fourier transform infrared spectroscopy ( ftir ) characterization of the cnx before and after irradiation for 24 h in the presence and absence of nip showed negligible differences ( figures s13s15 ) . thus , cnx showed long - term activity and stability for simultaneous alcohol oxidation and h2 production . the xps spectra also support that nip is not physically adsorbed on the cnx surface during the period of irradiation and acts as a homogeneous catalyst in the system . the color of the colloidal suspension prepared with cnx , nip , and 4 - mba changed almost instantaneously from pale yellow to intense blue upon irradiation , and this color persisted during 24 h of continuous irradiation ( figure s16 , inset ) . when nip was replaced with a sacrificial electron acceptor , ammonium persulfate , or air ( o2 ) , the color of the suspension became yellow upon irradiation , whereas upon the substitution of 4 - mba with sacrificial electron donor edta , the color remained blue . the observed color change is therefore attributed to photogenerated electrons in the photosensitizer . in order to characterize the color change upon irradiation of the cnx , uv vis absorption spectra were recorded for cnx ( 5 mg ) in kpi ( 3 ml , 0.02 m , ph 4.5 ) with and without 4 - mba ( 30 mol ) after simulated solar light irradiation ( am 1.5 g ) for 30 min . the suspension prepared with 4 - mba turned intense blue immediately upon irradiation , and consequently a broad absorption peak at = 650 nm was obtained ( figure s16 ) , a direct spectroscopic observation of the trapped electrons in the cnx . in the absence of 4 - mbano color change was observed , indicating that 4 - mba reductively quenches the photoexcited state of the cnx . nip ( 50 nmol ) was added to the blue pre - irradiated suspension using an airtight syringe under n2 , and the peak at = 650 nm was monitored every 15 min for 1 h , while the suspension was stirred in the dark ( figure 5a ) . a significant decay in the absorption peak was observed in the first 15 min ( 1/2 = 10 min ) , indicating transfer of the trapped electrons from cnx to nip . the photoexcited electrons were thus collected by nip , and the color of the suspension became yellow again . in a control experiment , a nip - free kpi solution was added to another blue cnx suspension pre - irradiated for 30 min and the solution remained blue with no significant change in the absorption spectra . these ultralong - lived trapped electrons can be stored in the dark for a prolonged period of time ( 30 min ) in cnx and transferred to nip when available . ( a ) spectrophotometry of the appearance ( during irradiation ) and disappearance ( upon addition of nip in the dark ) of photoexcited electrons in cnx at = 650 nm . a suspension with cnx ( 5 mg ) and 4 - mba ( 30 mol ) in kpi ( 0.02 m , ph 4.5 , 3 ml ) was irradiated ( am 1.5 g ) for 30 min , followed by addition of nip ( 50 nmol , 400 l ) or kpi ( 400 l ) . ( b ) two photoreactors were prepared with cnx ( 5 mg ) and 4 - mba ( 30 mol ) in the absence of nip in an aqueous kpi solution ( 0.02 m , ph 4.5 , 3 ml ) and irradiated with 1 sun irradiation ( am 1.5 g , 25 c ) . both of these photoreactors were taken into the dark after 4 h of irradiation , while nip ( 50 nmol ) was added to one of them . the pair of hollow and filled symbols of the same shape and color corresponds to h2 and aldehyde production , respectively , under the specified reaction conditions . to demonstrate quantitative h2 evolution in the dark phase , two photoreactors were prepared using cnx ( 5 mg ) and 4 - mba ( 30 mol ) in kpi in the absence nip and were irradiated under simulated solar light ( am 1.5 g ) for 4 h ( figure 5b ) . then , both systems were protected from light , and nip ( 50 nmol ) was added to only one of the photoreactors ; the h2 production was monitored for both ( table s8 ) . the same effect was observed , the photoreactor kept in the dark without nip did not show any h2 production in the 20 h dark phase , whereas the vial containing nip showed a substantially increased h2 production . the amount of aldehyde produced after 24 h was the same as after 4 h for both of the systems ( independent of the nip ) indicating that alcohol oxidation ceased as soon as the vials were removed from light . these results are in agreement with efficient alcohol oxidation by cnx , using the photogenerated holes , even in the absence of an electron acceptor ( figure 2 ) . thus , cnx can be charged during the light phase by 4 - mba oxidation and the electrons can be released in the absence of light to carry out proton reduction to h2 , which enables the temporary decoupling of the oxidative and reductive half - reactions . to gain a better understanding of the kinetics behind electron transfer in this system , transient absorption spectroscopy ( tas ) measurements , tas investigations confirmed that electron transfer to nip is the rate - limiting step for the photocatalytic system ( figure 6 ) . titration experiments carried out by increasing the nip concentration did not quench the excited state of the photosensitizer , cnx * , eliminating the possibility for an oxidative quenching mechanism ( figures s17 and s18 ) . summary of mechanism and kinetic rates from tas measurements with suspensions of cnx ( 15 mg ml ) , nip ( up to 24 m ) , and 4 - mba ( 10 mm ) in an aqueous kpi solution ( 0.02 m , ph 4.5 , 25 c ) . representative lifetimes , calculated using 3 s as the initial time , are indicated near reaction arrows . photoexcitation of cnx produced a photoinduced absorption signal in the range of 5501000 nm ( figure s19 ) , which matches that observed upon irradiation of cnx with 4 - mba ( figure s16 ) . this spectral feature did not show any evolution over the decay time nor was the shape sensitive to additives , suggesting a single excited state species absorbing over this spectral range . kinetics were probed at 750 nm in order to reduce the influence of the strong photoluminescence at wavelengths near 550 nm . the intrinsic decay of cnx ( figure s20 ) yields a representative lifetime ( 1/2 ) of 21.6 s , which is the time where 50 % of the initial ( at 3 s ) excited state population has decayed by half . the tens of microsecond time scale of the decay was quite comparable to those found in metal oxide photocatalysts such as hematite and tio2 . furthermore , the same type of dispersive power law decay dynamics is found in the carbon nitrides studied as that for the metal oxides and has been attributed to bimolecular ( i.e. , electron hole ) recombination . the exponent of the power law is significantly smaller than unity ( 0.35 ) , indicating that charge trapping / detrapping may play a considerable role in excited state dynamics of cnx , as also indicated by the slow time scale of this recombination process . we next performed 4 - mba titration experiments to elucidate the kinetics of 4 - mba oxidation . as the concentration of 4 - mba increases , a long - lived component of the decay becomes dominant ( figure s21 ) , assigned to long - lived electrons formed following hole scavenging by 4 - mba . for 10 mm 4 - mba , these long - lived electrons account for about 75 % of the initial amplitude ( figure 7 ) . assuming a bimolecular dynamic quenching process , analysis of the concentration - dependent yield and rate of formation of the long - lived electrons ( see supporting information for details ) provides a reaction rate constant of 1.4310 m s ( figures s22 and s23 ) . the analysis also informs us of a slow background reaction rate k0 of 8200 s , which we tentatively attribute to hole scavenging by small amounts of impurities or h2o and explains the nonzero absorption seen in the millisecond regime in the absence of 4 - mba . however , the shape of the decay is more indicative of quenching occurring on time scales faster than the instrument response of 3 s , perhaps by static quenching . specifically , the decrease in amplitude seen before 1 ms in the presence of 10 mm 4 - mba shows a 1/2 of roughly 20 s ; that is , indistinguishable fast phase 1/2 values are observed with or without 4 - mba . the yield of long - lived electrons plateaus for a higher concentration of 4 - mba , a possible indication that deeply trapped electrons which decay with microsecond dynamics are unable to participate in the charge transfer reaction . the cnx / 4 - mba reaction thus appears to take place faster than the 20 s relaxation kinetics of cnx . upon comparison to a previously reported photocatalytic system using ascorbic acid ( aa ) as the sacrificial electron donor , the cnx / 4 - mba reaction time scale is faster than that of the reduction of an oxidized ru dye ( rup - tio2 / aa ) and maybe comparable to the reduction time scale of the excited state of the ru dye ( rup / aa ) . transient decays probed at = 750 nm of cnx ( 1.2 mg ml ) and cnx ( 1.2 mg ml ) suspensions in aqueous kpi solution ( 0.02 m , ph 4.5 , 25 c ) following = 355 nm excitation . the same spectral feature is seen with and without the addition of 4 - mba , and the oxidation of 4 - mba consumes holes , which confirms the assignment of the blue - colored solution deriving from photogenerated electrons in the cnx ( figure s16 ) . the same observation was also made with meoh as a hole scavenger ( figure s19 ) . an analogous increase of the photogenerated electron lifetime in tio2 has been observed upon the addition of meoh as a hole scavenger . this further implies that formation of separated charge carriers in cnx occurs within 3 s . we attempted to quantify the rate of the electron transfer reaction from cnx to nip , but the time scale of this reaction was too long for direct observation by tas . both in the absence or presence of 4 - mba , addition of nip did not affect the relaxation kinetics of cnx ( figures s17 and s18 ) . the upper time limit of our measurements was 2 s due to settling of the heterogeneous cnx dispersion . we thus conclude that the lifetime of long - lived electrons in cnx is longer than 2 s , consistent with the persistent blue color observed upon irradiation of cnx / 4 - mba ( see above ) . similarly , the reaction lifetime for cnx electron transfer to nip is also longer than 2 s , in line with the disappearance of the blue color that takes place over 30 min upon nip addition ( figure 5a ) . by taking into account the nip concentration , the upper bound of the bimolecular rate constant is thus set to 210 m s. we have compared the tas results of cnx and the unfunctionalized cnx to gain insights into the significant differences in efficiency . surprisingly , for the studied time scale , we observed slower decay kinetics ( 1/2 = 60.2 s ) for cnx dispersions compared to the photocatalytically more efficient cnx ( figures 7 and s24 ) . instead of increasing the lifetime of reactive charges , the increased efficiency of cyanamide - functionalized carbon nitride seems to stem from higher hole transfer reactivity toward the oxidation reaction . in particular , we have observed no changes in the decay kinetics of cnx upon the addition of 4 - mba , supporting an inefficient alcohol oxidation step also observed in the bulk photocatalysis experiments . negligible change in the fermi levels rules out the change in band energies as the reason for the enhanced photocatalytic activity for cnx , eliminating the possibility of differences in driving force from the electron transfer side . rather , it is plausible that oxidation of 4 - mba by cnx is aided by more favorable hydrogen bonding interactions between the anionic cyanamide moiety on the surface of the material and the benzyl alcohol , in addition to ion dipole forces originating from the cyanamide groups , increasing the preassociation and effectiveness of static quenching and / or effectively increasing the basicity of the carbon nitride and the driving force for reaction . these observations highlight the necessary consideration of both charge photogeneration and separation as well as complex electronit is well - known that proton reduction by nip occurs via successive multiple electron and proton transfers . by taking this and the results obtained from the characterization of the system into account , it is suggested that the alcohol oxidation also occurs via multiple electron and proton transfer steps . a stepwise mechanism is proposed in which irradiation of cnx results in light absorption and charge separation . the photogenerated hole in the material is first reductively quenched by the 4 - mba for selective alcohol oxidation . the photoexcited electrons accumulated in the cnx are then transferred to the nip , which carries out reduction of aqueous protons . the rate of photogenerated electron transfer from cnx to nip is slower than the rate of reductive quenching , giving rise to an intense blue color . studies are ongoing to develop a better understanding of the full mechanism of this coupled alcohol oxidation and proton reduction hybrid system . in summary , we report a closed redox system for simultaneous photocatalytic alcohol oxidation and proton reduction , utilizing the cyanamide functionalized carbon nitride , cnx , and a hydrogenase - inspired molecular h2 evolution catalyst , nip . the hybrid system consists of earth abundant materials and functions in a purely aqueous solution and at room temperature in the absence of sacrificial reagents . under optimized conditions , a remarkable eqe of 15 % ( = 36010 nm ) , a h2 production rate ( tofnip ) of 76.37.6 h , and a tonnip of 408.840.9 were achieved , with a 4 - mba conversion yield of 83.08.3 % with quantitative selectivity for 4 - mbad . nip system is straightforward to prepare and provides a novel platform to produce a valuable organic chemical and a h2 fuel simultaneously , and the products are also spontaneously separated in the solution and gaseous phase , respectively . the degree of substrate oxidation in the system can be controlled by tuning the strength and selectivity of the electron acceptor . the suspension system also benefits from functioning in a stirred bulk solution where radial diffusion to the dispersed carbon nitride occurs , whereas conventional pec cells can suffer from diffusion limitations at the electrode surface . the lifetime of this hybrid system is limited by the stability of the molecular h2 evolution catalyst nip , whereas the cnx maintained its activity for at least 50 h of irradiation , providing a significant advantage over similar systems based on photodegrading molecular dyes . taken together , the results demonstrate that identification and design of photostable molecular catalysts could enhance the long - term photocatalytic activity of the hybrid system . the reported system also provides a potential pathway for extension into a broad range of other useful substrate oxidation reactions , as well as applications into co2 and other reduction processes , by altering the molecular catalyst used . tas results confirmed that the cyanamide groups on the surface of the material play a vital role in providing enhanced catalytic activity toward selective substrate oxidation , which outperforms possible charge recombination reactions . the material can accumulate ultralong - lived trapped electrons during irradiation and effectively transfer these charge carriers to a catalyst in a dark phase . work is currently in progress to further characterize the ultralong lived trapped electrons and to develop viable systems and devices that are not limited by the diurnal availability of sunlight by temporarily and spatially decoupling light absorption and oxidation from fuel generation . all reagents for the synthetic part of the work were purchased from commercial suppliers and used directly without any further purification . the buffer solutions were prepared using analytical grade reagents and titrated to the desired ph with a ph meter ( mettler toledo ; seveneasy ) . cnx was prepared by heating melamine to 550 c for 12 h under ar following a published procedure . the yellow solid obtained was then thoroughly ground using a pestle and mortar prior to further analysis and applications . cnx was prepared from ground cnx and kscn ( weight ratio of 1:2 ; dried overnight at 140 c under vacuum ) and heated at 400 c for 1 h and then at 500 c for 30 min under ar as previously reported . after cooling to room temperature , the residual kscn was removed by washing with water , and the product was dried under vacuum at 60 c . platinized cnx and cnx ( containing 8 wt % pt ) were prepared following a published procedure , by in situ photodeposition from h2ptcl6 ( 10 l aqueous solution corresponding to 8 wt % pt loading ) in a phosphate buffer ( kpi ) solution ( 3 ml , 0.02 m , ph 4.5 ) containing 4 - mba . samples of cnx were pressed onto indium foil for xps , and the spectra were collected on an axis ultra ( kratos analytical , manchester ) xps instrument with charge neutralization . the spectra were processed using the software casaxps 2.3.16 and referenced with the adventitious carbon 1s peak at 284.80 ev . binding energies were compared with the nist standard reference database 30 unless otherwise specified . attenuated total reflectance ftir spectra were collected with a perkinelmer uatr two spectrometer equipped with a diamond crystal . uvvis difference spectra of cnx were recorded on an edinburgh instruments fs5 spectrofluorometer equipped with an integrating sphere . synchronous scans ( ex = em ) were run for samples after irradiating for 30 min with a solar light simulator equipped with an am 1.5 g filter . the absorption spectra were generated by comparing samples before and after irradiation using fluoracle software supplied with the fs5 instrument . the simultaneous 4 - mba oxidation and proton reduction photocatalytic experiments were performed and studied as follows : polymeric cnx ( 5.0 mg ) was placed in a borosilicate glass photoreactor ( total volume 7.74 ml ) equipped with a magnetic stir bar . a kpi solution containing 4 - mba and nip was prepared ( total volume 3 ml ) and added to the photoreactor , which was then tightly sealed with a rubber septum . the vials were then purged for 15 min with n2 containing 2 % ch4 , an internal gas chromatograph ( gc ) standard , before irradiation . all photocatalytic experiments were carried out using a newport oriel solar light simulator ( 100 mw cm ) equipped with an am 1.5 g filter . ir irradiation was removed from all the experiments using a water filter , and uv irradiation was eliminated using a 400 nm cutoff filter ( uqg ) , whenever specified . the photoreactor was stirred and kept at a constant temperature ( 25 c ) with continuous water circulation through a water - jacketed reservoir during the light experiments . the amount of h2 was quantified using an agilent 7890a series gc equipped with a 5 molecular sieve column against an internal ch4 standard . the gc oven was kept at 45 c , and n2 was used as the carrier gas at a flow rate of approximately 3 ml min . samples of the headspace gas ( approximately 20 l ) were taken from the photoreactor for analysis using an airtight hamilton syringe at regular time intervals . the amounts of alcohol and aldehyde were quantified by nuclear magnetic resonance ( nmr ) spectroscopy as follows : the photoreactor was removed from the light source , the suspension was centrifuged ( 10 min at 10000 rpm ) to remove cnx , and the supernatant solution was extracted with ch2cl2 ( 34 ml ) , dried over mgso4 , filtered , and concentrated to dryness under reduced pressure . the residue was then characterized by using h nmr spectroscopy on a bruker dpx 400 spectrometer at 298 k. comparison of the methyl peaks of 4 - mba and 4 - mbad , as well as the distinctive aldehyde ( coh ) peak , allowed for the determination of a quantitative ratio of the starting material to product ( figure s4 ) . the workup procedure was confirmed to leave the ratio of starting material to product unaffected . three vials containing different 4 - mba / 4 - mbad ( 1:2 , 1:1 , and 2:1 ) ratios were prepared following the described procedure for the photocatalytic experiments ( except the irradiation step ) , and the initial 4 - mba / 4 - mbad ratios were preserved after working up the solutions as described above . the eqe was determined by using a solar light simulator ( lot lsn 254 ) equipped with a ( lot msh 300 ) monochromator to irradiate the samples at = 36010 nm ( accurate to a fwhm of 10 nm ) with a light intensity ( i ) of i = 4.43 mw cm , which was measured on a power meter ( ilt 1400 , international light technologies ) . the eqe was calculated as follows : where nh2 is the moles of photogenerated h2 , na is avogadro s constant , h is the planck constant , c is the speed of light , tirr is the irradiation time , and a is the cross - sectional area of irradiation . to ensure reproducibility , the solar light simulator and gc were calibrated regularly . throughout the photocatalytic experiments , no gradual decrease in the amount of ch4 ( internal gc standard ) was observed , indicating that there was no significant leakage of ch4 in the vial . all analytical measurements were carried out in triplicates , and data are reported as mean value standard error ( ) . the experimental setup used an nd : yag laser ( opotek opolette 355 ii , 7 ns pulse width ) as the excitation source .355 nm light was generated from the third harmonic of the laser and transmitted to the sample through a light guide with a diameter of 0.5 cm to photoexcite the cnx . typical excitation power densities of 460 j cm and laser repetition rates of 1.1 hz were used . as the changes of reflectance observedare low ( 1 % ) , the transient signal is taken to be directly proportional to the concentration of excited state species . long pass filters ( comar instruments ) between the lamp and sample were used to minimize the short wavelength irradiation of the sample . a 5 cm path length cuvette filled with di water was also placed in the beam path as an ir filter . diffuse reflectance from the sample was collected by a 2 diameter , 2 focal length lens and relayed to a monochromator ( oriel cornerstone 130 ) to select the probe wavelength . an additional high pass filter was positioned in front of the monochromator to reduce laser scatter . time - resolved intensity data were collected with a si photodiode ( hamamatsu s3071 ) . data at times faster than 3.6 ms were recorded by an oscilloscope ( tektronics dpo3012 ) after passing through an amplifier box ( costronics ) , while data slower than 3.6 ms were simultaneously recorded on a national instrument daq card ( ni usb - 6251 ) .15 mg ml of the cnx was dispersed in 20 mm kpi buffer adjusted to ph = 4.5 . acquisitions were triggered by a photodiode ( thorlabs det10a ) exposed to laser scatter . data were acquired and processed using home - built software written in the labview environment . the experimental setup and photoluminescence of the sample limit analyses to time scales longer than about 3 s . from the shape of the decay , it is clear that some excited state decay occurs before 3 s . as such , while the t50 % of the cnx decay is used for further kinetic analysis , a shorter value would be obtained if we could follow the entirety of the decay immediately following photoexcitation .\noutput:\n" }, { "from": "agent", "value": "solar water - splitting represents an important strategy toward production of the storable and renewable fuel hydrogen . the water oxidation half - reaction typically proceeds with poor efficiency and produces the unprofitable and often damaging product , o2 . herein , we demonstrate an alternative approach and couple solar h2 generation with value - added organic substrate oxidation . solar irradiation of a cyanamide surface - functionalized melon - type carbon nitride ( ncncnx ) and a molecular nickel ( ii ) bis ( diphosphine ) h2 - evolution catalyst ( nip ) enabled the production of h2 with concomitant selective oxidation of benzylic alcohols to aldehydes in high yield under purely aqueous conditions , at room temperature and ambient pressure . this one - pot system maintained its activity over 24 h , generating products in 1:1 stoichiometry , separated in the gas and solution phases . the ncncnx nip system showed an activity of 763 mol ( g cnx ) 1 h1 toward h2 and aldehyde production , a ni - based turnover frequency of 76 h1 , and an external quantum efficiency of 15 % ( = 360 10 nm ) . this precious metal - free and nontoxic photocatalytic system displays better performance than an analogous system containing platinum instead of nip . transient absorption spectroscopy revealed that the photoactivity of ncncnx is due to efficient substrate oxidation of the material , which outweighs possible charge recombination compared to the nonfunctionalized melon - type carbon nitride . photoexcited ncncnx in the presence of an organic substrate can accumulate ultralong - lived trapped electrons , which allow for fuel generation in the dark . the artificial photosynthetic system thereby catalyzes a closed redox cycle showing 100 % atom economy and generates two value - added products , a solar chemical , and solar fuel ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: udp - glucuronosyltransferases ( ugts ) are a mammalian superfamily of phase ii metabolizing enzymes , of which ugt1a and ugt2b are the most important subfamilies . to date , 25 ugt1a and ugt2b isozymes have been identified in humans ( mackenzie et al . 2005 ) . ugts catalyze the binding of glucuronic acid to endo - and exogenous compounds , e.g. , hormones or drugs . this is an important process that increases their solubility in water and aids in their urinary excretion . ugts have been found in a variety of organs and tissues , including liver , lungs , intestinal mucosa , brain , uterus and placenta , in both animals and humans ( mackenzie et al . ugt activity is regulated by various pre - and posttranslational mechanisms , e.g. , hormones , liver - enriched transcription factors , ligand - activated transcription factors , and the aryl hydrocarbon receptor ( bock 2010 ; ishii et al . very little is known on the extent and intrinsic regulation of human placental ugt activity . external factors , e.g. , enzyme - inducing drugs , ethinyl estradiol or cigarette smoke may increase ugt activity . some ugt1a4 - substrates , e.g. , the antiepileptic drug lamotrigine ( ltg ) , may even induce their own metabolism to a certain degree ( hussein and posner 1997 ; may et al . ltg serum concentrations fall by over 50 % during pregnancy , most presumably due to increased glucuronidation ( de haan et al . this may lead to loss of seizure control and the necessity to increase the ltg dose ( petrenaite et al . it is unlikely that pregnancy - induced hemodilution plays a major role in this phenomenon as hematocrit usually decreases by only 1015 % ( klajnbard et al . moreover , it has been shown that increased glucuronidation of ltg is the most probable mechanism ( ohman et al . it is reasonable to assume that most of this glucuronidation takes place in the liver . however , ugt has been found in many other tissues also , including the placenta . the placenta is a major detoxifying organ , protecting the fetus from potentially harmful compounds by means of various enzymes and transporters ( myllynen et al . in contrast to the placental expression of cytochrome p450 enzymes , data on placental ugt expression is scarce . so far , few different isozymes of the ugt2b - family have been detected in placental tissue . ugt1a protein expression was found in first trimester human placenta , but not in placenta at term ( collier et al . a more recent study found dna - transcripts of ugt1a6 , but no other ugt1a isozyme , in placental tissue ( zhang et al . since it is unknown where in the body the increased glucuronidation of ltg takes place , and which role the placenta plays in this context , we wished to investigate whether ugt1a4 is expressed in human placenta . placentas from 10 healthy , non - smoking , normal - term pregnant women ( controls ; samples 110 ) and four non - smoking , normal - term pregnant women using ltg without enzyme - inducing co - medication ( ltg - users ; samples 1114 ) were taken immediately after cesarean section or vaginal delivery and microsomes of the villous part were prepared within 30 min . briefly , villous tissue from the placenta was homogenized in 0.25 m icecold sucrose and the homogenate was centrifuged at 12,000 g for 20 min to obtain a postmitochondrial supernatant ( pms ) . the pms was subjected to microsomal aggregation by addition of ca and then centrifuged again at 27,000 g for 15 min . the microsomal pellets obtained were suspended in 0.1 m tris buffer ( ph 7.4 ) , added glycerol ( final glycerol concentration was 15 % ) and stored at 80c until use . the protein concentrations were determined using the bradford protein assay ( bio - rad laboratories ) , with bovine serum albumin as the protein standard ( bradford 1976 ) . sds polyacrylamide gel electrophoresis ( sds page ) was performed according to the method of laemmli ( 1970 ) , with minor modifications . placental microsomal proteins were denaturated by boiling for 4 min in sample treatment buffer ( 0.125 m tris hcl , ph 6.8 , 20 % glycerol , 4 % sodium dodecyl sulfate , 0.004 % bromophenol blue , and 10 % 2 - mercaptoethanol ) . placental microsomal proteins were loaded ( 30 g per lane ) and separated using 420 % linear gradient gel in trishcl ( bio - rad laboratories ) for approximately 50 min at 200 v. human ugt1a4 supersomes ( bd gentest ) were treated in sample treatment buffer analogous to the placental microsomes and then loaded as standard . the resolved proteins were transferred electrophoretically to a 0.45 - m nitrocellulose membrane ( bio - rad laboratories ) at 100 v for 1 h. the nitrocellulose sheets were blocked overnight by treatment with 5 % skim milk in tris - buffered saline ( tbs ) containing 0.1 % tween20 . the membranes were rinsed and treated for 1 h with a 1:1,000 dilution of wb - ugt1a primary antiserum ( bd gentest ) or a 1:500 dilution of a specific ugt1a4 primary antiserum ( santa cruz biotechnology ) . the membranes were rinsed four times for 10 min and incubated for 1 h with a 1:1,000 dilution of horse radish peroxidase ( hrp ) conjugated goat anti - rabbit igg ( bd gentest ) or a 1:5,000 dilution of hrp conjugated donkey anti - goat igg ( santa cruz biotechnology ) , respectively . membranes were washed four times with tbs and visualized using western lightning chemiluminescence reagents according to the manufacturer s instructions ( bd gentest and santa cruz biotechnology ) followed by light detection on luminescence detection film ( amersham bioscience ) . placentas from 10 healthy , non - smoking , normal - term pregnant women ( controls ; samples 110 ) and four non - smoking , normal - term pregnant women using ltg without enzyme - inducing co - medication ( ltg - users ; samples 1114 ) were taken immediately after cesarean section or vaginal delivery and microsomes of the villous part were prepared within 30 min . briefly , villous tissue from the placenta was homogenized in 0.25 m icecold sucrose and the homogenate was centrifuged at 12,000 g for 20 min to obtain a postmitochondrial supernatant ( pms ) . the pms was subjected to microsomal aggregation by addition of ca and then centrifuged again at 27,000 g for 15 min . the microsomal pellets obtained were suspended in 0.1 m tris buffer ( ph 7.4 ) , added glycerol ( final glycerol concentration was 15 % ) and stored at 80c until use . the protein concentrations were determined using the bradford protein assay ( bio - rad laboratories ) , with bovine serum albumin as the protein standard ( bradford 1976 ) . sds polyacrylamide gel electrophoresis ( sds page ) was performed according to the method of laemmli ( 1970 ) , with minor modifications . placental microsomal proteins were denaturated by boiling for 4 min in sample treatment buffer ( 0.125 m tris hcl , ph 6.8 , 20 % glycerol , 4 % sodium dodecyl sulfate , 0.004 % bromophenol blue , and 10 % 2 - mercaptoethanol ) . placental microsomal proteins were loaded ( 30 g per lane ) and separated using 420 % linear gradient gel in trishcl ( bio - rad laboratories ) for approximately 50 min at 200 v. human ugt1a4 supersomes ( bd gentest ) were treated in sample treatment buffer analogous to the placental microsomes and then loaded as standard . the resolved proteins were transferred electrophoretically to a 0.45 - m nitrocellulose membrane ( bio - rad laboratories ) at 100 v for 1 h. the nitrocellulose sheets were blocked overnight by treatment with 5 % skim milk in tris - buffered saline ( tbs ) containing 0.1 % tween20 . the membranes were rinsed and treated for 1 h with a 1:1,000 dilution of wb - ugt1a primary antiserum ( bd gentest ) or a 1:500 dilution of a specific ugt1a4 primary antiserum ( santa cruz biotechnology ) . the membranes were rinsed four times for 10 min and incubated for 1 h with a 1:1,000 dilution of horse radish peroxidase ( hrp ) conjugated goat anti - rabbit igg ( bd gentest ) or a 1:5,000 dilution of hrp conjugated donkey anti - goat igg ( santa cruz biotechnology ) , respectively . membranes were washed four times with tbs and visualized using western lightning chemiluminescence reagents according to the manufacturer s instructions ( bd gentest and santa cruz biotechnology ) followed by light detection on luminescence detection film ( amersham bioscience ) . ugt1a proteins were detected , using wb - ugt1a primary antibody , in all four placental samples from women using ltg ( fig . two bands were detected in every sample , and one of them co - migrated with the ugt1a4 standard . western blot analyses with ugt1a4 primary antibody also illustrated the presence of bands , further indicating the presence of the ugt1a4 isozyme ( fig .1 a ) corresponded to neither the ugt1a4 nor the ugt1a1 standard , which indicates the presence of another isoform of ugt1a in the placenta samples . the wb - ugt1a primary antibody used in this study detects several isoforms of human ugt1a ( ugt1a1 , 1a3 , 1a4 , 1a6 , 1a7 , 1a9 , and 1a10 ( mobility range 5258 kda ) ) . in a previous study , dna - transcripts of ugt1a6 , but not ugt1a1 , ugt1a3 , ugt1a4 , ugt1a5 , ugt1a7 , ugt1a8 , ugt1a9 , and ugt1a10 , have been found in human placenta ( zhang et al . the fact that this latter study did not find evidence for placental expression of ugt1a4 may be due to considerable methodological differences ( dna - transcripts vs. ugt1a4 protein itself ) and the use of a different kind of placental tissue preparation.fig .1 ugt1a ( a ) and ugt1a4 ( b ) protein expression in term placenta from women using lamotrigine . microsomal proteins were isolated from placental tissue and analyzed by western blotting with antibodies for the ugt1a protein subfamily ( a ) or ugt1a4 isozyme ( b ) . equal amounts ( 30 g ) of microsomal total protein were loaded for each lane . the patterns shown are representative for a series of two or three replicate blots ugt1a ( a ) and ugt1a4 ( b ) protein expression in term placenta from women using lamotrigine . microsomal proteins were isolated from placental tissue and analyzed by western blotting with antibodies for the ugt1a protein subfamily ( a ) or ugt1a4 isozyme ( b ) . equal amounts ( 30 g ) of microsomal total protein were loaded for each lane . the patterns shown are representative for a series of two or three replicate blots ugt1a proteins were also detected in placental samples from the 10 control women not using ltg . a representative immunoblot of microsomes from control women ( showing samples 17 ) and ugt1a4 standard is shown in fig . 2 . although equal amounts of total placental protein and ugt1a4 standard were used in the different immunoblots , weaker bands of ugt1a were detected in the placentas of the control group ( fig .2 ) , compared to the ltg - user group ( fig . 1 ) . however , our experiments , which were designed to detect ugt1a and ugt1a4 qualitatively , were not suited for quantitative measurements . thus , the observed differences in band intensity do not prove real quantitative differences in ugt1a4 expression . it has , though , previously been found that ltg induces its own metabolism ( hussein and posner 1997 ) . therefore , it may be hypothesized that ltg - users express higher levels of ugt1a4 than controls due to enzyme induction . microsomal proteins were isolated from placental tissue and analyzed by western blotting with a specific antibody for the ugt1a protein subfamily . equal amounts ( 30 g ) of microsomal total protein were loaded for each lane . the pattern shown is representative for a series of two or three replicate blots ugt1a protein expression in term placenta from healthy subjects . microsomal proteins were isolated from placental tissue and analyzed by western blotting with a specific antibody for the ugt1a protein subfamily . equal amounts ( 30 g ) of microsomal total protein were loaded for each lane . the pattern shown is representative for a series of two or three replicate blots ugt1a4 mrna has previously been found in human liver , stomach , small intestine , colon , kidney , bladder , trachea and ovary , but not in brain , lung , adrenal gland , breast , uterus and testis ( kaivosaari et al . , our study is the first one to demonstrate ugt1a4 protein in human term placenta . this finding suggests that placental ugt1a4 activity may contribute to the significant fall of ltg serum concentrations during pregnancy . further studies , e.g. , quantitative western blots and metabolizing experiments with placental tissue or whole perfused placentas are necessary to confirm our findings and to evaluate this hypothesis .\noutput:\n" }, { "from": "agent", "value": "the placenta contains a large variety of metabolizing enzymes , among them udp - glucuronosyltransferase ( ugt ) . several ugt2b isozymes have so far been detected in human placenta , but little is known on placental expression of ugt1a isozymes . the antiepileptic drug lamotrigine ( ltg ) is a ugt1a4 - substrate , and its serum concentration falls by over 50 % during pregnancy , leading to impaired seizure control . the placenta may be involved in this . microsomes from term placentas of 4 ltg - users and 10 healthy control subjects were prepared . western blot analysis detected ugt1a proteins in all placentas . the presence of ugt1a4 in placenta from ltg users was confirmed with ugt1a4 commercial standard and a specific ugt1a4 primary antibody . since ltg is primarily metabolized by ugt1a4 and this isozyme is shown to be present in placenta at term , it may be hypothesized that the placenta is involved in the fall of ltg serum concentrations during pregnancy ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: nosocomial hepatitis c virus ( hcv ) infection within dialysis units is well described . international guidelines advocate standard infection control precautions as the primary method of minimizing patient - to - patient hcv transmission . cohorting hcv - infected patients and segregating them from the main dialysis unit may further reduce the risk of hcv transmission . however , cross - infection between cohorted patients could lead to the superinfection of patients with another hcv genotype or the re - infection of patients whose infection had resolved naturally or following anti - viral treatment . we describe a haemodialysis patient who was re - infected with hcv of a different genotype than his original infection . he received an estimated 20 u of packed red blood cells for treatment of renal anaemia . his transplant failed in 2002 due to chronic allograft nephropathy and he was tested for hcv infection as he returned to dialysis . hcv genotype 2 with a viral load of 7312217 copies / ml ( 2708228 iu / ml ) was discovered . this transplant failed due to recurrence of his original glomerulonephritis and he developed end - stage kidney disease within 4 years . according to local policy , he was cohorted with hcv - infected patients when he resumed haemodialysis in 2007 . in september 2009 , he commenced a 24 - week course of pegylated interferon therapy . this remained negative 6 months after completion of therapy , by definition a sustained virological response ( svr ) . the patient was routinely tested for hcv after returning from a holiday abroad in january 2011 and was found to be weakly positive for hcv antigen ( ag ) ( 44 pg / ml ) . retrospective testing of a serum sample collected in december 2010 confirmed that hcv ag and rna were then absent . subsequent hcv rna testing in february 2011 detected hcv rna with a viral load of 7791 iu / ml . genotyping using the versant hcv genotype 2.0 assay ( inno - lipa ) identified this to be hcv genotype 3a . this indicated hcv re - infection rather than a relapse of the patient 's original hcv genotype 2 infection . there was no evidence to support hcv transmission outside the dialysis unit or within the patient 's holiday dialysis unit . a review of the genotypes of all hcv viraemic patients within the unit identified two additional patients with hcv genotype 3a infection . one patient ( patient x ) had received dialysis alongside the index patient ( i.e. same shift , room and nurse but different dialysis machine ) throughout the month of december , at which time his hcv viral load was 69000000 iu / ml . phylogenetic analysis of fragments of the e1 / e2 region , including the hypervariable region , of hcv rna from patient x and the index patient demonstrated that there was a strong possibility that both viruses were genetically related ( see figure 2 ) . we concluded that the index patient had been infected with hcv genotype 3a from patient x while they were being cohorted together for dialysis . phylogenetic tree demonstrating closely related hcv genotype 3a subtypes of index patient and patient x. unrooted neighbour - joining ( nj ) tree hcv nucleotide sequences in the e1 / e2 region ( 300 bp ) with outgroup d26556 ( genotype 3b ) . the nucleotide sequences of index patient and x1 , x2 and x3 of patient x are indicated ( see arrow ) . the nj tree generated by heuristic search using paup . the tree was constructed using the gtr + g + i model of nucleotide substitution selected by jmodeltest with 1000 bootstrap replicates . this report describes a dialysis patient with chronic hcv genotype 2 infection who achieved an svr following pegylated interferon therapy but was re - infected with hcv genotype 3a . epidemiological and molecular investigations identified a highly viraemic patient , with whom the patient was being cohorted for dialysis , as the likely source of the re - infection . intensive surveillance for hcv infection is practiced in the dialysis unit and only two cases of nosocomial hcv transmission have been detected among the 496250 dialysis treatments delivered here since hcv testing became available in 1992 . this seroconversion rate of 0.4 per 100000 dialysis treatments compares favourably to international experience . international guidelines , supported by observational data , maintain that standard infection control precautions alone are sufficient to prevent nosocomial hcv transmission . however , breaches in infection control procedure in dialysis facilities are not infrequently described and have resulted in large hcv outbreaks . cohorting of hcv - infected patients together in dialysis units separated from main dialysis units may offer additional protection to non - infected patients . indeed , impressive reductions in rates of hcv seroconversion have been observed to occur in many dialysis units following implementation of such a strategy . consequently , we cohort hcv - positive dialysis patients together in a unit adjacent to our main dialysis unit in the belief that this practice provides maximal protection to the majority of our patients ( i.e. the non - infected ) without placing excessive demands on hospital resources . cohorting should , however , augment standard infection control precautions and not replace them . as illustrated by this case , lapses in the strict enforcement of standard precautions can result in hcv superinfection and re - infection , respectively , among actively infected and recently treated hcv - positive dialysis patients being cohorted together . to our knowledge , only one previous report has described hcv re - infection occurring in a haemodialysis population . in this case series , five haemodialysis patients from three dialysis centres in brazil were re - infected with hcv . re - infection was distinguished from relapse on the basis of a different hcv genotype . firstly , these patients were re - infected with hcv prior to achieving an svr . secondly , an epidemiological analysis was not reported consequently , it is not clear that all infections were nosocomially acquired . lastly , no information is provided regarding infection control policy in the referring dialysis units . the experience of hcv re - infection in this patient directly informed a change in local policy regarding the management of hcv - infected dialysis patients who achieve an svr . in the absence of any international precedent , this revised guideline was based on the rationale that hcv relapse in a dialysis patient is extremely unlikely once an svr has been achieved . from an infection control standpoint , therefore , patients with an svr can be safely considered to have resolved infection . this revised local policy was reflected in a recently drafted amendment to the irish blood - borne viruses in haemodialysis , capd and renal transplantation national guidelines 2010 . this updated guideline will be available on the irish health protection surveillance centre website in early 2012 . the main proposed changes are as follows : if hcv rna is undetectable at the end of treatment , the patient can be dialysed in isolation until 6 months after end of treatment or be dialysed in the multibedded unit but undergo hcv ag testing every 2 weeks.if hcv rna is undetectable 6 months after treatment ( svr ) , infection can be considered to be resolved . the patient can be dialysed in the multibedded unit and tested monthly for hcv ag.if an svr is not attained , the patient should be cohorted with hcv rna - positive patients . hcv genotyping should be performed to distinguish relapse from re-infection . standard infection control procedure is essential to prevent cross - infection between hcv - infected patients , especially for patients with very high viral load . if hcv rna is undetectable at the end of treatment , the patient can be dialysed in isolation until 6 months after end of treatment or be dialysed in the multibedded unit but undergo hcv ag testing every 2 weeks . if hcv rna is undetectable 6 months after treatment ( svr ) , infection can be considered to be resolved . the patient can be dialysed in the multibedded unit and tested monthly for hcv ag . an svr is not attained , the patient should be cohorted with hcv rna - positive patients . standard infection control procedure is essential to prevent cross - infection between hcv - infected patients , especially for patients with very high viral load . it is hoped that the publication of this case and the guidelines informed by it will result in a reduction of nosocomial hcv transmission in haemodialysis units .\noutput:\n" }, { "from": "agent", "value": "we report the case of a 45 - year - old haemodialysis patient who achieved a sustained virological response ( svr ) following pegylated interferon therapy for hepatitis c virus ( hcv ) genotype 2 infection . he was subsequently cohorted with other hcv - infected dialysis patients and became re - infected with hcv genotype 3a . epidemiological and molecular investigations identified a highly viraemic hcv genotype 3a - infected dialysis patient as the likely source of this infection . this critical incident informed a revision to local and national infection control policy regarding the dialysis management of patients who achieve an svr following anti - viral treatment ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: methylglyoxal ( pyruvaldehyde or 2 - oxo - propanal ) is a widely dispersed , reactive bis - electrophile found in food and beverages , cigarette smoke , and automobile exhaust . the major endogenous source of methylglyoxal is from the enzymatic and nonenzymatic breakdown of carbohydrates ; it is also a product of lipid peroxidation and threonine catabolism . methylglyoxal covalently modifies both dna and proteins , forming protein adducts with arginine ( mg - h1 , mg - h2 , and mg - h3 ) , and lysine ( n - ce - lys ) side chains and dna adducts with guanine and adenine bases ( figure 1 ) . interestingly , the mg - h3 adduct can undergo 2 - electron oxidation to mg - i3 , which hydrolyzes back to arg and methylglyoxal . a related adduct of glyoxal ( ethane -1,2-dione ) with a cysteine side chain ( s - cm - cys ) has also been characterized , and methylglyoxal has been shown to inactivate a cysteine protease suggesting the formation of the corresponding s - carboxyethyl - cys adduct . protein and dna adducts of glyoxal , methylglyoxal , and related species are collectively referred to as advanced glycation end - products ( ages ) . ages have been implicated in the pathologies of many diseases , including cancer . elevated levels of ages are observed in diabetics , and there is a long established epidemiological link between diabetes and higher risk of certain cancers ( liver and pancreatic ) . protein and dna adducts of methylglyoxal and glyoxal . since methylglyoxal and glyoxal are bis - electrophiles , they react with dguo to form an initial 1 , n - cyclic dguo adduct ( mg - dguo and gx - dguo ) ; these adducts form reversibly but can rearrange to stable n - ( 1 - carboxyethyl ) - dguo ( ce - dguo ) and n - ( 1 - carboxymethyl ) - dguo ( cm - dguo ) , respectively . the ce - dguo adduct has been identified from calf thymus dna and cultured cells treated with methylglyoxal , and in background levels of human melanoma cells and in plasmid dna isolated from escherichia coli . ce - dguo has been observed in the urine of healthy humans , and increased levels were measured from tissue samples from diabetic and uremic patients . as suchthe bifunctional nature of glyoxal and methylglyoxal can also lead to the formation of dna dna , proteinprotein cross - links have been observed when chinese hamster ovary , human skin , or human endothelial ( ecv304 ) cells were exposed to methylglyoxal . additionally , cross - links between the dguo adduct of glyoxal and other dna bases have been characterized and observed from the dna of exposed cells . protein cross - link with the exonuclease deficient klenow fragment ( kf ) of e. coli dna polymerase i. the level of the cross - link increased by 50 % if nabh4 was added , suggesting that the cross - linking mechanism involved a schiff base intermediate . the cross - linking was most efficient if the single - stranded region of the template strand consisted of a run of dguo s , indicating that dguo was involved in the cross - link . the reaction of dguo , methylglyoxal , and n - acetyl - derivatives of several amino acids ( gly , ala , lys , arg , his , cys , trp , asn , and asp ) was examined , and cross - links between n - acetyl - lys ( aclys ) and n - acetyl - cys were reported . however , the chemical nature of the cross - links was not determined . on the basis of the mechanism of formation of ce - dguo and related protein adducts of methylglyoxal ( vide infra ) , we hypothesized that the structure of the dguo , aclys , and methylglyoxal cross - link to be that shown in figure 2 . structure of the dguo , methylglyoxal , and n - aclys cross - link 1 . dguoh2o ( 5 mm ) and aclys ( 5 mm ) were mixed in sodium phosphate buffer ( 100 mm , ph 7.4 ) or sodium carbonate bicarbonate buffer ( 100 mm , ph 9.0 ) containing 1 mm edta . methylglyoxal ( 20 mm , 5 mm , 1.25 mm , or 0.5 mm ) was then added , and the reaction was incubated at 37 c with continuous shaking for 7 days . at the end of the incubation time , the samples were filtered through a 0.45 m millipore cartridge , and aliquots of the reaction mixture were analyzed by hplc - uv ( gradient ii ) with the remainder of the samples stored at 70 c pending uplc - esi - ms / ms analysis in negative ion srm mode ( see supporting information for details of the ms analysis ) . negative ion srm mode was shown to be more sensitive for the analysis of the ce - dguo adducts . the above reaction was also performed in which methylglyoxal was added in 20 equal portions over 2.5 days . the methylglyoxal portions ( 0.25 mm ) were added every 2 h ( 8 additions on the first and second days and 4 on the third day ) so that the final concentration was 5 mm . the reaction was incubated at 37 c for an additional 10 h and analyzed as above . the experiments described above were performed and analyzed in triplicate . as a control , the cross - linking reaction was repeated in which each of the components was omitted . in these cases , cross - link 1 was not observed upon ms analysis . aliquots of the reaction of dguo , aclys , and methylglyoxal were diluted by 5-fold ( v / v ) with h2o . a portion of this sample ( 10 l ) was mixed with a solution of [ c3n1 ] - 1 ( 10 ng , 10 l ) . a portion of this mixture ( 10 l ) was then subjected to uplc - esi - ms / ms analysis performed in negative srm mode using uplc gradient i by monitoring the transition corresponding to a major fragment ion observed upon cid fragmentation of cross - link 1 in an ltq mass spectrometer ( transitions of m / z 508392 for cross - link 1 and m / z 512396 for [ c3n1 ] - 1 ) . the quantitation of cross - link 1 using uplc - esi - ms / ms was repeated twice . dguoh2o ( 5 mm ) and the synthetic acavagkagar peptide ( 5 mm ) were mixed in sodium phosphate ( 100 mm , ph 7.4 ) buffer containing 1 mm edta . methylglyoxal ( 5 mm ) was then added and the mixture incubated at 37 c with continuous shaking for 48 h. at the end of the incubation , the sample was filtered through a 0.45 m millipore cartridge and stored at 70 c pending uplc - esi - ms / ms analysis in positive srm mode ( see supporting information for details of the ms analysis ) . the experiments described above were performed and analyzed in triplicate . as a control , the reaction was repeated in which each of the components was omitted . no cross - link was observed by ms analysis if the peptide , dguo , or methylglyoxal was omitted . the chemical synthesis of the putative cross - link is outlined in scheme 1 ( see supporting information for experimental procedures ) . fmoc - ( s ) - ala was coupled to the side chain amino group of the aclys methyl ester in 78 % yield ( hbtu , ipr2net , dmf ) . the fmoc group was removed using diisopropylethylamine in dmso and reacted in situ with o - ( 2 - ( trimethylsilyl ) ethyl ) -2-fluoro-2-deoxyinosine ( 3 ) under conditions previously employed by tretyakova and co - workers . the o - protecting group was removed by brief treatment with acetic acid at ambient temperature , and the modified nucleotide ( 4 ) was obtained in 45 % yield after purification by hplc . hydrolysis with lioh afforded the desired cross - link ( s ) - 1 in 83 % yield after purification by solid phase extraction . the cross - linking reaction was anticipated to afford a mixture of stereoisomers at the position adjacent to n. thus , ( r ) - 1 was synthesized starting from fmoc - ( r ) - ala by the same sequence . the nmr chemical shifts of the 2 - protons , which are in the typical range for deoxyguanosine , and the deoxyribose coupling constants suggest that the nucleoside exists predominantly in the anti glycosidic conformation with the deoxyribose largely ( 63 % ) in the 2 - endo conformation . the mass spectrum of cross - link 1 ( m / z 508.2 [ m h ] ) and its fragmentation in negative ion mode is shown in figure 3b . the initial characteristic loss of the deoxyribose unit ( 116 da , 508392 ) is followed by decarboxylation of the lysine portion ( 44 , 392349 ) . interestingly , the amide bond involving the lysine side chain readily fragmented ( 145 , 349204 ) at low collision energy ( 10 ev ) . an authentic standard of the ce - dguo adduct was also synthesized from the reaction of dguo and glyceraldehyde . the mass spectral fragmentation of ce - dguo in negative ion mode involved decarboxylation ( 44 , 338294 ) followed by neutral loss of the deoxyribose ( 116 , 294178 ) ( see figure s17 of the supporting information ) , which is consistent with a previous analysis . cross - link 1 and ce - dguo adducts were also characterized by 1d - and 2d - h nmr spectroscopy ( see figure s8s13 of the supporting information ) . uplc chromatogram of the full scan mode ( 1051100 da ) , reconstructed ion chromatograms of srm scan mode and ms fragment ions , and ms product ion spectrum of the dguo - methylglyoxal - aclys cross - link ( 1 ) . ( a ) from the reaction of dguo , aclys , and methylglyoxal ( 1:1:4 ) . the cross - linking reaction was initially investigated using a 4-fold molar excess of methylglyoxal in phosphate buffer ( 100 mm , ph 7.4 ) at 37 c for 7 days . hplc analysis of the reaction showed three predominant products ( figure 4a ) having retention times ( tr ) between 16 and 19 min . uplc - ms analysis ( figure 4b ) of the reaction revealed that the major products had masses consistent with 2:1 methylglyoxal - dguo adducts ( m / z 410 [ m h ] ) . minor products , which coeluted with the 2:1 adducts , had masses consistent with a 1:1 adduct between methylglyoxal and dguo ( m / z 338 [ m h ] ) and are likely to be the diastereomeric 1 , n - cyclic adducts ( mg - dguo ) and ce - dguo . under the conditions of the reaction , the cross - links were not detectable by hplc ( figure 4a , insert ) but could be readily identified by uplc - esi - ms ( figure 4b ) . with standards in hand , we identified the diastereomeric cross - links of interest ( figure 3a ) , and their mass spectra were identical to those of the standard ( figure 3b ) . ( a ) hplc chromatogram for the reaction of dguo , aclys , and methylglyoxal in a 1:1:4 ratio ( ph 7.4 ) . ( b ) uplc chromatogram of full scan mode ( 1051100 da ) , reconstructed uplc - esi - ms / ms and srm ( 116 da ) ion chromatograms from the reaction of dguo , aclys , and methylglyoxal ( 1:1:4 ) . ( c ) hplc chromatogram from the cross - linking reaction with a slow addition of methylglyoxal . structures of the 2:1 dguo adducts of methylglyoxal and glyoxal have been proposed previously ( 57 , figure 5 ) . the formation of the proposed 2:1 adducts are anticipated to be reversible and therefore expected to equilibrate with dguo or the 1:1 adduct after isolation ; this was in fact shown to be the case for the 2:1 glyoxal - dguo adduct ( 7 ) . the 2:1 methylglyoxal adducts we observed were stable , which would seemingly rule out the previously proposed structures . our data for one of the 2:1 methylglyoxal - dguo adducts ( tr 16.6 min , figure 4c ) suggested 8 ( stereochemistry unknown ) as the structure , and details of the nmr and mass spectrometric analyses will be reported separately . the proposed structure is related to the previously characterized 2:1 methylglyoxal - arginine adduct 9 . we assume that the remaining 2:1 adducts are diastereomers of 8 ( tr 17.1 and 17.9 min , figure 4c ) , although it is possible that other isomeric species are present and that their distribution is dependent upon the reaction conditions . an isotopically labeled cross - link standard was synthesized starting from [ c3n1 ] - fmoc - ( s ) - ala in order to quantitate the cross - links by stable isotope dilution mass spectrometry . a calibration curve was developed by plotting the ratio of the cross - link ( s ) - 1 ( 0.25100 ng ) / [ c3n1 ] - ( s ) - 1 ( 50 ng ) versus the integrated ratio of ( s ) - 1 ( m / z 508392 ) / [ c3n1 ] - ( s ) - 1 ( m / z 512396 ) . the calibration curve was linear over the concentration range examined ( r = 0.998 , figure s18 and s19 of the supporting information ) . the yield of the cross - link when methylglyoxal was in 4-fold excess was 0.06 % at ph 7.4 ( 100 mm phosphate buffer , 37 c ) based on the initial dguo concentration . consistent with the previous work of murata - kamiya and kamiya , the yield of cross - linking was higher at ph 9.0 ( 0.3 % ) , which may reflect the protonation state of the side chain amino group of aclys . we hypothesized that formation of the stable 2:1 methylglyoxal - dguo adduct is much more favorable than the cross - linking chemistry , thereby suppressing cross - link formation . the reaction was re - examined with equimolar ratio of the three components , and with methylglyoxal as the limiting reagent . however , the yield of the cross - link with equimolar concentrations of three components was 1.1 % at ph 7.4 , which is nearly 20 times higher than when methylglyoxal was used in 4-fold excess . the yield of the cross - link further increased to 3.6 % and 7.1 % when methylglyoxal was the limiting reagent ( 0.25 and 0.1 equiv respectively ) based on the initial methylglyoxal concentration . isolated yields of 5.3 % and 4.9 % were realized for the ( s ) - and ( r ) - cross - links when one equivalent of methylglyoxal was added slowly ( 0.05 equiv every 2 h ) over time . equimolar ratios of methylglyoxal , dguo , and acavagkagar peptide ( m / z 842.5 [ m + h ] and 421.8 [ m + 2h ] ) were reacted in ph 7.4 phosphate buffer for 48 h at 37 c . mass spectrometric analysis of the reaction in positive ion mode is shown in figure 6a ( also see figure s20 of the supporting information for the reconstructed ion chromatogram ) . the product observed at m / z 1163.5 [ m + h ] and 582.2 [ m + 2h ] is consistent with the peptide - methylglyoxal - dguo cross - link ( 10 ) ; additionally , the ion with m / z of 524.3 is consistent with the [ m + 2h ] ion of the cross - link following the neutral loss of the deoxyribose in source ( m / z 582.2524.3 ) . the ms spectrum of the m / z 524.3 ion is shown in figure 6b ( collision energy 35 ev ) , and table 1 lists the theoretical b - and y - fragment ions for the peptide cross - link involving the lysine side chain at position 5 . the most prominent ion in the ms spectrum is at m / z 421.8 ( figure 6b ) ; this mass corresponds to the [ m + 2h ] ion of the starting peptide and results from fragmentation of the amide bond involving the lysine side chain . this amide bond readily fragmented in the ms spectrum of the dguo - methylglyoxal - aclys ( 1 ) at low collision energy . however , b2b9 and y2y9 fragment ions were clearly observed consistent with a gua - methylglyoxal cross - link at the lys residue ( figure 6b and table 1 ) and strongly supports the structural assignment . ( a ) full - scan spectrum from the reaction of dguo , methylglyoxal , and the acavagkagar peptide in 100 mm , ph 7.4 phosphate buffer . ( b ) collision - induced dissociation ( cid ) mass spectrum of the m / z 524.3 [ m + 2h ] . this ion results from the in source , neutral loss of the deoxyribose ( see table 1 for theoretical b - and y - ion masses ) . minor products ( figures 6a and 7 ) were observed that had masses consistent with the cross - link plus an additional mol of methylglyoxal ( 11 , m / z 1235.4 [ m + h ] and 618.1 [ m + 2h ] ) and the cross - link plus an additional mol of methylglyoxal and loss of h2o ( 12 , m / z 1217.2 [ m + h ] and 609.1 [ m + 2h ] ) ( figures s22 and s23 of the supporting information ) . fragmentation of the product ions suggested that in addition to the lysine cross - link , the c - terminal arginine residue was also modified . the latter is consistent with the cross - link and the mg - h1 , mg - h2 , or mg - h3 arginine adduct ( 12 ) ; although only the mg - h1 adduct is shown , it is likely that a mixture of these isomeric adducts are present . the product with m / z 1235.4 [ m + h ] and 618.1 [ m + 2h ] is likely to be the cyclic vicinal diol that results from the addition of methylglyoxal to arginine and is a probable precursor of mg - h1 , mg - h2 , and mg - h3 modifications ( 11 ) . the mg - h1 , mg - h2 , and mg - h3 arginine adducts ( 14 ) were also observed at m / z 896.5 and 448.8 for the singly and doubly charged ions , respectively ( figure s25 of the supporting information ) , as well the diol precursor ( 13 ) at m / z 914.6 and 457.8 ( figure s24 of the supporting information ) . we note that the ce - lys adduct of the peptide would also be consistent with m / z 914.6 [ m + h ] and 457.8 [ m + 2h ] ; fragmentation of the m / z 914.6 revealed a nearly complete b - and y - ion series . the b5b8 and y1y4 fragment ions for the ce - lys and arg adducts are predicted to differ , and the observed fragment ions are clearly consistent with the arg - adduct ( 13 ) . the m / z 986.3 and 493.8 ions are consistent with the singly and doubly charge peptide plus 2 mols of methylglyoxal ( + 144 ) . further fragmentation was consistent with the mg - h13 modifications of arg and the ce - lys adduct ( 15 ) , which undergoes decarboxylation ( 44 ) ( figure s26 of the supporting information ) . a reasonably abundant product with m / z 926.5 and 463.8 for the singly and doubly charged ions is also observed . a complete y - ion series was observed upon cid consistent with the addition of 84 da to the arg . products identified by the mass spectrometric analysis of the reaction of dguo , methylglyoxal , and the acavagkagar peptide in 100 mm , ph 7.4 phosphate buffer . proposed mechanisms for the formation of the ce - dguo adduct from mg - dguo are shown in scheme 2 . the mechanism could potentially proceed through the ring closed mg - dguo or through a ring - opened n - dguo adduct ( 16 ) , in which the aldehyde is hydrated . dehydration of the carbinolamine involving the n - atom would provide intermediate 17 or 19 . in the case of the open - chain pathway , 17 could undergo a 1,2 - hydride shift ( pinacol rearrangement ) to the ce - dguo adduct . alternatively , imine 17 could undergo tautomerization to the enamine 18 , which is the enol form of the ce - dguo adduct ( amadori rearrangement ) . amadori rearrangement leads to imide 21 through 20 or a 1,2 - hydride of 19 gives 21 directly ( not shown ) . the proton adjacent to n will be derived from the solvent in the amadori pathway , whereas it is derived from the aldehyde proton of methylglyoxal in the 1,2 - hydride shift mechanism . therefore , conducting the adduction reaction in deuterated buffer can differentiate the amadori versus 1,2 - hydride shift pathways . methylglyoxal and dguo were incubated at 37 c in deuterated phosphate buffer ( 100 mm , ph 7.4 ) for 7 days . to enhance the yield of the ce - dguo adducts , the formation of the 2:1 adduct was lower under these conditions compared to reactions when equimolar or excess methylgyoxal was added at once . the later eluting ce - dguo isomer , assigned as the ( s ) - isomer based on previous work , coeluted with one of the 2:1 methylglyoxal - dguo adducts under the chromatographic conditions used . an expanded region of the spectrum is shown in figure 8a , and the full spectrum is shown in figure s14 of the supporting information . the analysis showed that the proton adjacent to the n - atom and carboxylate group , which normally appears as a quartet at 4.22 ppm , was not observed from the product obtained in deuterated buffer , and the adjacent methyl group at 1.36 ppm , which was normally a doublet , was now a singlet . the proton spectrum was integrated relative to the integration of the anomeric proton ( 6.19 ppm ) . this showed that the h8 had exchanged by 60 % , while the methyl group had 25 % deuterium incorporation . the latter probably occurred as methylglyoxal , rather than at the ce - dguo adduct stage . no exchange of the proton adjacent to the n - atom and carboxylate group was observed when a ( r ) - ce - dguo standard was incubated in deutrated buffer for 7 days at 37 c , indicating that the deuterium atom was incorporated as part of the mechanism of ce - dguo formation from dguo and methylglyoxal . the results are consistent with the amadori rearrangement mechanism but do not distinguish between the ring - opened or ring - closed pathways . we hypothesize that formation of cross - link 1 proceeds through a related mechanism ( vide infra ) , and similar results were obtained when aclys , dguo , and methylglyoxal were reacted in deuterated buffer . an apparent quintet at 4.37 ppm was not observed for the methine proton adjacent to the n - atom of cross - link ( r ) - 1 and the methyl group at 1.30 ppm appeared as a singlet instead of a doublet ( figure 8b and s15 of the supporting information ) . nmr analysis of the reaction of dguo and methylglyoxal ( a ) and dguo , aclys , and methylglyoxal ( b ) in deuterated buffer ( top ) versus standards ( bottom ) . dpcs are intermediates of natural dna processing or result through exposure to environmental , occupational , or endogenous toxicants , as well as chemotherapeutic agents . dpcs are formed by numerous mechanisms , and one of the major challenges to studying them is their structural heterogeneity . dpcs can result from oxidative damage to dna or through reaction of the protein with oxidation products such as oxanine , ribonolactone lesions , or further oxidation of 8 - oxoguanine . such cross - links involve direct reaction with amino acid side chains and dna . dpcs are also formed with bifunctional electrophiles , which can react with a nucleophilic site on both the dna and amino acid side chain . formaldehyde , dihaloalkanes , butadiene diepoxide , and some heavy metals are examples of environmental / occupational agents that form dpcs . dpcs have also been characterized from chemotherapeutic agents such as nitrogen mustards and cisplatin . dpcs can form reversibly with abasic sites or enal adducts of dguo via schiff base formation with a lysine side chain or the n - terminal amino group ; such dpcs have been reductively trapped . comparative mutagenesis between glyoxal and methyglyoxal in african green monkey kidney ( cos - 7 ) cells using the supf reporter gene showed dramatically different mutagenic spectra . while glyoxal resulted largely in base - pair substitutions ( mainly g t transversions ) , multiple base deletions were the predominant mutation observed for methylglyoxal . interestingly , exposure of human skin cells to methylglyoxal and glyoxal showed that methylglyoxal was significantly more likely to form cross - links , while glyoxal induced dna strand breaks . in one study , dpc formation was reported to be 10-fold higher with methylglyoxal than glyoxal in vitro . it is tempting to attribute the higher level of deletion mutations observed in the methylglyoxal mammalian mutagenesis studies to dpcs . the supf containing dna vector was treated with glyoxal or methylglyoxal then immediately transfected into the cells for these initial mutagenesis experiments ; the nature and distribution of the dna adducts were not determined . in a more recent study , a dna vector was analyzed by mass spectrometry after modification by methylglyoxal , and the mg - dguo adduct accounted for less than 1 % that of the diastereomeric ce - dguo adducts , and the 2:1 adducts were not detected . the major mutation observed after transfection into human fibroblast cells was g t transversions , with deletions accounting for less than 10 % of the observed mutation frequency . oligonucleotides containing ce - dguo have been synthesized in a sequence specific and stereospecific manner , allowing for replication studies in vitro and intact cells . dna polymerases prefer to insert dctp opposite a template ce - dguo resulting in error - free or nonmutagenic bypass . however , when replications errors occur purines are most commonly misinserted opposite the ce - dguo lesions leading to g t and g c transversions . ce - dguo was weakly mutagenic in e. coli resulting in low levels of g t transversions with a mutagenic frequency of 0.5 % ; the mutagenicity increases to 1.1 and 2.3 % for the r - and s - isomers in a pol iv deficient background , suggesting that this polymerase participates in the replication bypass of the ce - dguo adducts in vivo . interestingly , the ce - dguo adducts were not mutagenic when replicated in wild - type murine embryonic fibroblast cells . however , g a transitions and g t transversions were observed in a pol deficient background suggesting a role for this polymerase in the error - free bypass of the ce - dguo adducts in mammalian cells . pol and pol iv are both part of the dinb family of dna polymerases . altogether , the most recent random and site - specific mutagenesis data suggests that ce - dguo is weakly mutagenic and not likely to be the source of the deletion mutations observed in early experiments . it is possible that residual mg - dguo reacts with cellular proteins after transfection and that the resulting dpcs give rise to deletions . model studies with amino acids suggested that lysine and cysteine , but not arginine , formed cross - links with the mg - dguo adduct . two mechanisms for ce - dguo formation have been proposed involving either a series of tautomerizations ( amadori rearrangement ) or a 1,2 - hydride shift ( pinacol rearrangement ) as the key step ( scheme 2 ) . the mechanism can occur through a ring - opened n - adduct or the ring - closed 1 , n - exocyclic adduct . we hypothesized that the mechanism of lysine cross - link formation is related to the mechanism of ce - dguo formation . nucleophilic attack of the side chain amino group of lysine forming a carbinolamine intermediate ( 22 , scheme 3 ) rather than hydration of the open - chain aldehyde , followed by dehydration and amadori rearrangement affords cross - link 1 with a stable amide linkage . alternatively , the nucleophilic opening of the cyclic imide 21 by lysine also leads to cross - link 1 . although the labeling studies can not distinguish between the ring - opened or ring - closed pathways , it was previously noted that the yield of cross - link improved in the presence of nabh4 . this observation is more consistent with the ring - opened pathway since further dehydration of 23 would provide a bis - imine intermediate that could be reduced to form a stable cross - link . both diastereoisomers of the proposed cross - link ( 1 ) were synthesized according to scheme 1 and used as authentic standards . additionally , an isotopically labeled standard , [ c3n1 ] - ( s ) - 1 , was synthesized starting from [ c3n1 ] - fmoc - ( s ) - ala , which was used to quantitated cross - link 1 by stable isotope dilution mass spectrometry . initial model cross - linking reactions were examined with dguo , aclys , and excess methylglyoxal . large excesses of the electrophile are typically used for such model reactions owing to the low nucleophilicity of the nucleoside bases . these conditions gave vanishing low yields of the cross - link with the 2:1 adducts being highly favored . we hypothesized that the favorable formation of the 2:1 adducts , which are of questionable biological relevance , were greatly out competing the cross - linking reaction and reasoned that lower concentrations of methylglyoxal might make cross - link formation more competitive . consistent with this hypothesis , the yield of the cross - link significantly improved through lowering the methylglyoxal concentration . the methylglyoxal concentration in cells is likely to be much lower than that in in vitro model systems . our results suggest that the cross - linking chemistry may be more efficient under cellular conditions than might be predicted based on model systems that use a large excess of the electrophile . the reaction of equimolar concentrations of dguo , methylglyoxal , and a model peptide , acavagkagar , was examined by mass spectrometry . the most abundant products ( figure 6a ) were identified as the arginine adducts of methylglyoxal ( 13 and 14 ) in addition to modification of both the arginine and lysine residues ( 15 ) . products with masses consistent with the predicted methylglyoxal cross - link between the lysine side chain and dguo were also observed ( 1012 ) . the cross - link products , which also include products in which the arg is also modified , appear to be in lower abundance than the simple peptide adducts . the cid spectra are consistent with cross - linking to the lysine side chain . the major fragment ion results from neutral loss of the dguo - methylglyoxal unit to the original peptide . this fragmentation suggests a possible method for detection of the cross - link from proteomic analysis of cells or tissue samples . the cross - linked tryptic peptide could be identified by monitoring for the neutral loss the dguo - methylglyoxal mass ( 321 da ) after digestion of the dna portion of the dpc to a single nucleoside or loss of gua - methylglyoxal base ( 205 da ) after deglycosylation of the dna similar to that in figure 6b . the mass of the resulting peptide fragment would represent a tryptic peptide with a missed cleavage site since the lysine involved in cross - link formation is unlikely to be a substrate for trypsin . reactive electrophiles other than methylglyoxal are formed from the degradation of carbohydrates , which can also modify proteins and dna . it was observed that amines can accelerate the modification of dna and in some cases be incorporated into the product . for example , the reaction of guanosine with glucose in the presence of n - propylamine resulted in amide cross - links related to 1 ( figure 9 ) . the work provided the first insight into the structure of dpcs derived from maillard products . subsequently , cross - link 1 was observed from the reaction of ac - lys , dguo , and either dihydroxyacetone or glyceraldehyde . it is possible that methylglyoxal is the reactive bis - electrophile in these examples or that perhaps other electrophilic maillard products are capable of forming the same cross - link . a related glyoxal cross - link between lys side chains has also been characterized in vitro from the reaction of glyoxal with bovine serum albumin ( bsa ) and human lens proteins . interestingly , the yield of this cross - link for the in vitro reactions increased at lower glyoxal concentrations . the reaction of dguo , methylglyoxal , and either n - aclys or a lys - containing peptide has been examined as a model for dpc formation and analysis . the structure of the stable cross - link between dguo , n - aclys , and methylglyoxal ( 1 ) was hypothesized based on the mechanism of ce - dguo formation ( schemes 2 and 3 ) . importantly , we observed that cross - link formation increased at lower methylglyoxal concentrations . the amide linkage between the lysine side chain and the methylglyoxal - dguo readily fragmented during ms analysis at low collision energy . the neutral loss of this portion to give the original peptide can potentially be monitored as a means to identify cellular proteins involved in dpcs by methylglyoxal .\noutput:\n" }, { "from": "agent", "value": "methylglyoxal is a mutagenic bis - electrophile that is produced endogenously from carbohydrate precursors . methylglyoxal has been reported to induce dna protein cross - links ( dpcs ) in vitro and in cultured cells . previous work suggests that these cross - links are formed between guanine and either lysine or cysteine side chains . however , the chemical nature of the methylglyoxal induced dpc have not been determined . we have examined the reaction of methylglyoxal , deoxyguanosine ( dguo ) , and n - acetyllysine ( aclys ) and determined the structure of the cross - link to be the n2 - ethyl -1-carboxamide with the lysine side chain amino group ( 1 ) . the cross - link was identified by mass spectrometry and the structure confirmed by comparison to a synthetic sample . further , the cross - link between methylglyoxal , dguo , and a peptide ( acavagkagar ) was also characterized . the mechanism of cross - link formation is likely to involve an amadori rearrangement ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: telemedicine is the use of information and communication technology to provide health care services for people in remote areas where the health care providers are not available . telemedicine has been shown to be feasible and cost - effective and to provide organizational benefits and to improve patients ' satisfaction . telecardiology , an application of telemedicine in cardiology , has been shown to improve the standard of cardiac care by providing diagnostic support for health professionals to safely manage their patients . studies have demonstrated that telecardiology improves the management of cardiac diseases in remote and rural populations in a cost - effective manner , reduces the number of unnecessary hospital referrals and admissions , results in avoidance of travel for patients in rural and remote areas , and improves health professionals ' knowledge base . meta - analysis studies showed that telemedical monitoring of patients with chronic heart failure can improve overall survival by 17 % to 47 % during 6 to 12 months of follow - up . moreover , some systematic reviews showed that telemedicine has a beneficial effect on health related quality of life among patients with heart failure . in jordan , many patients with cardiac diseases in the rural and remote locations receive cardiac care by general practitioners because of the scarcity of cardiologists in these areas . other patients need to travel to receive these services in tertiary hospitals in amman , the capital of jordan . because of geographic distance and costly travel , many patients find referral to a cardiologist very difficult . thus , provision of telecardiology services in remote areas in jordan could have its greatest impact . a telemedicine initiative was undertaken through the jordan healthcare initiative ( jhi ) to facilitate access to quality healthcare services for patients and clinicians from two remote hospitals in northern and southern regions in jordan to specialists at a tertiary hospital in amman . this study was conducted to assess the impact of live interactive telecardiology consultations on diagnosis and disease management and assess if telecardiology was associated with improvement in patients ' quality of life and time - and cost - savings . two teleclinics have been successfully implemented and are fully operational in two remote hospitals in north and south of jordan . the first clinic was launched in 2011 at mafraq governmental hospital ( mgh ) in the north of jordan and the second was launched in 2012 at queen rania hospital ( qrh ) in the south of jordan . the two clinics connect patients from the north and south of jordan with specialists at prince hamzah hospital ( phh ) in amman . a pretest - posttest one - group design was used to evaluate the process and outcomes of the teleconsultations that took place in the period between september 2013 and january 2014 . all consecutive patients who attended or referred to the teleclinics for suspected cardiac problems in both hospitals during the study period were included in the study . for each patient , the physician or the nurse in the remote hospitals filled the consultation request form and scheduled an appointment for the patient in the teleclinic within one week of the patient 's first visit . in the day of the visit to the teleclinic and at the end of consultation session , the study team ( two nurses in each hospital ) interviewed patients using face - to - face interview and filled all study questionnaires . the quality of life questionnaires were filled again after 8 weeks of the last visit to the clinic using phone interview . all efforts were made to ensure that the phone interview is conducted according to prespecified protocol and guidelines set by the principle investigator to ensure high data quality and to minimize the losses to follow - up . the sample size that was needed to detect a medium effect size in the change of quality of life for patients with cardiologic conditions after receiving the teleconsultation at a power of 80 % and level of significance of 0.05 was calculated as 53 subjects . the ethical approval was obtained from the institutional review board at jordan university of science and technology . different aspects were assessed in the evaluation process . all questionnaires and forms used in this studyenglish questionnaires were translated into arabic using a forward - backward translation method and were subsequently adapted to the jordanian culture . all nurses were trained on data collection methods including phone interview and face - to - face interview , on ethical aspects of research conduct , and on all study procedures . this form was filled for each patient during the initial visit by the physician or the trained nurse in the remote hospitals and a copy was sent to the specialists in the main hospital by fax or email . the form included information about the patient 's demographics , chief complaint , disease or condition category , medical history , current medications , and provisional diagnosis and treatment plan . all necessary and available documents such as lab results that may help to reach the diagnosis or the proper treatment and follow - up of the patient were sent to the specialist . this form was filled by the physicians or trained nurses in the remote hospitals at the end of the consultation . the record form included information about the final diagnosis and proper treatment plan as agreed upon by the physician and the specialist . one question was used to assess the physician perception about whether the communication with the specialist helped the physician to reach better diagnosis and / or treatment plan . a change in diagnosis was defined as whether the consultant cardiologist 's diagnosis was different from that of the referring physician 's diagnosis at the completion of the initial telecardiology consultation . a change in disease management was defined as whether the cardiologist recommended treatment plan that was different from what was recommended by the referring physician . a structured questionnaire was filled using face - to - face interview at the end of the teleconsultation session to assess the patients ' perception and satisfaction with the telemedicine application and determine its effect on the quality of care and health outcomes . the questionnaire consisting of 15 items was divided into different sections to give a complete picture on different domains including medical improvement , time - and cost - savings , the telemedicine preparation , proper case management , and diagnosis and treatment . likert scale of five responses was used to rate the individual items in each domain with higher scores indicating better satisfaction . the total satisfaction score was calculated by summing the responses of all individual items in the questionnaire and transformed to a score on 0100 scale . one generic quality of life questionnaire ( arabic version of the short form ( sf - 8 ) questionnaire ) and selected questions from the minnesota living with heart failure questionnaire ( lihfe ) for patients with heart disease were used to assess the quality of life . the sf - 8 was constructed to replace the sf - 36 and sf - 12 in population health surveys in the u.s . and internationally . accordingly , it has been translated and linguistically validated for use in more than 30 countries and languages including arabic language using iqola project methods . the lihfe has been translated into 33 languages including arabic language ( even though some of the translations may not have undergone a full linguistic validation methodology ) . the patients ' judgment was based on how much his / her heart condition influenced the specific activity over the last week . the questionnaires were filled in the same day of the teleconsultation using face - to - face interview method and the same questionnaires were filled 8 weeks later using phone interview method to assess the changes in the quality of life as a result of teleconsultation . sf - 8 consists of eight items , each representing one health profile dimension : general health perception , physical functioning , role functioning - physical , bodily pain , vitality , social functioning , mental health , and role functioning - emotional . each item of sf - 8 and lihfe was then scored on a 0 to 100 range so that the lowest and highest possible scores are 0 and 100 , respectively , with a high score of sf - 8 and low score of lihfe defining a more favorable health state . the sf - 8 scale score and lihfe score represent the average for all items in the scale that the respondent answered . improvement in quality of life after telemedicine application compared to the baseline was analyzed using paired t - test . a p value of less than 0.05 was considered statistically significant . a total of 76 patients ( 53.9 % males and 46.1 % females ) attended the telecardiology clinics in the two remote hospitals between september 2013 and january 2014 . the age of patients ranged from 18 to 93 years with a mean ( sd ) of 49.0 ( 13.4 ) year . less than one - third of patients ( 30.3 % ) were younger than 45 years . the majority of telecardiology consultations were done in mgh and the majority of patients ( 81.6 % ) were referred from outside clinic / center . approximately one - half of patients ( 51.3 % ) had hypertension and one - third ( 33.3 % ) had diabetes mellitus . about 71.1 % of patients complained of chest pain and 53.3 % complained of shortness of breath . establishing or helping in diagnosis oras perceived by the referring providers , final diagnosis was established as part of the telecardiology consultations in 71.1 % of patients and changed from that of the referring provider in 17.1 % of patients . the diagnosis remained the same as that of the referring provider in 11.8 % of patients ( table 2 ) . the treatment plan was established for 77.3 % of patients as part of the teleconsultations and changed from that of the referring provider for 16.0 % patients . the referring providers perceived that the communication with the specialist helped them to reach the diagnosis and the treatment plan in all consultations . according to the final diagnosis , about half of patients ( 52.6 % ) had ischemic heart disease , 35.5 % had noncardiac problems , 5.3 % had heart failure , 5.3 % had cardiomyopathy , and 2.6 % had valvular heart disease . as a result of teleconsultations , 24 ( 31.6 % ) patients were treated locally in the same visit , 14 ( 18.4 % ) were scheduled for a follow - up by the specialist via teleclinic and treated , 8 ( 10.5 % ) were referred for outpatient diagnostics outside the region , 6 ( 3.9 % ) were referred to specialized consultants outside the region for evaluation and treatment , and 24 ( 31.6 % ) were referred for procedures and / or hospitalization . overall , patients ' travel was avoided for 38 ( 50.0 % ) who were managed locally . while none of the patients perceived that it is easy to access the specialist clinic in amman , 98.7 % of the patients stated that it was easy to access to the telecardiology clinic . the majority of patients perceived that the visit to the telecardiology clinic results in less travel time ( 96.1 % ) , less waiting time ( 98.1 % ) , and lower cost ( 100.0 % ) when compared to visiting the specialist clinic in the referral hospital ( table 3 ) . when patients were asked about what they would doif the telecardiology was not available , 88.2 % reported that they would travel to see the specialist , 10.5 % will see a noncardiologist in the same hospital , and one patient reported that he would have done nothing about it . the mean ( sd ) waiting time in the teleclinic was 43.2 ( 24.7 ) minutes and the mean consultation time was 19.5 ( 12.8 ) minutes . the total satisfaction score of patients with the services received ranged from 65.4 to 100 with a mean ( sd ) of 94.6 ( 7.6 ) indicating a high level of satisfaction . a total of 50 patients had completed sf - 8 and lihfe measurements at the baseline and follow - up . table 4 shows the changes in the quality of life after two months of telecardiology consultations . after two months of telecardiology consultations , the mean sf - 8 score increased significantly from 40.7 to 62.4 ( p 0.005 ) with a mean change from the baseline of 21.7 ( 95 % confidence interval : 15.3 , 28.0 ) . this implies that the telecardiology consultations resulted in an improvement in the quality of life and resulted in a more favorable health state . all sf - 8 domains had improved significantly after two months of telecardiology consultations except mental health domain . the highest improvements were seen in social functioning and role - emotional domains of sf - 8 . moreover , the baseline mean lihfe score decreased significantly from 47.8 to 34.9 after two months of telecardiology consultations indicating that there had been a meaningful improvement in patient 's quality of life since the previous measurement of lihfe scores at the baseline . various medical specialties use telemedicine to provide care to remote populations , thereby minimizing travel and reducing costs . telemedicine has a promising application in the diagnosis and management of cardiac diseases in remote and rural areas . however , there is still a debate on the benefits and effectiveness of telemedicine . to be adopted into everyday practice , telemedicine should show improved access to healthcare , improved quality of life , and cost - savings . telemedicine enables the remote exchange of data between patients and healthcare professionals to facilitate diagnosis , monitoring , and management of conditions . because of the shortage of cardiologists in remote and rural areas in jordan , the majority of patients with cardiac problems in these areas need to travel about 100300 kilometers to the tertiary hospitals in amman to receive the care . this study showed that such costly travels might be avoided for some patients as almost one - third ( 35.5 % ) of patients who attended the teleclinic had noncardiac problems and 50.0 % were treated locally without a need for traveling . besides , this study showed that the telecardiologists helped to establish the final diagnosis in 71.1 % of patients . another option for patients in the absence of teleclinic is to receive the care by noncardiologists . this option has implications on the diagnosis and treatment . in about 17.1 % of patients , telecardiology helped to establish the treatment plan for 77.3 % of patients and it has been changed from that of the referring provider for 16.0 % patients . therefore providing telecardiology care in remote areas of jordan would improve the access to health care and help to reach proper diagnosis and establish the treatment plan . avoidance of travel , by patients , their relatives , and health care professionals , is a major benefit of telecardiology . the majority of patients in this study perceived that the visit to the telecardiology clinic resulted in less travel time , reduced waiting time , and lower cost when compared to visiting the specialist clinic in amman . previous studies showed that telemedicine in remote areas may save costs by reductions in travel time . showed that 75 % of all analysed chronic chest pain referrals from gps to cardiologists were due to noncardiac causes , being either musculoskeletal or nonspecific in origin , and thus the travel can be avoided for a high percentage of patients . our study showed that telecardiology consultations resulted in a meaningful improvement in patient 's quality of life since the previous measurement of sf - 8 and lihfe scores . another pre / poststudy of telemedicine found significant improvements in role - physical , bodily pain , and social functioning domains of quality of life . on the other hand , some other studies that actually measured health related quality of life found no difference between telephone support and usual care . systematic reviews that have examined the effect of telemedicine on health related quality of life in heart failure showed that telemedicine is beneficial . this study was not intended to compare telecardiology to in - person cardiology care because telecardiology may still be superior to cardiologic care provided by nonspecialists . in conclusion , telecardiology care in remote areas of jordan would improve the access to health care , help to reach proper diagnosis and establish the treatment plan , and improve the quality of life . a study with a comparison group of patients who used the in - person cardiology care would provide stronger evidence on the effectiveness of telecardiology care .\noutput:\n" }, { "from": "agent", "value": "objectives . to assess the impact of live interactive telecardiology on diagnosis and disease management , patients ' quality of life , and time - and cost - savings . methods . all consecutive patients who attended or were referred to the teleclinics for suspected cardiac problems in two hospitals in remote areas of jordan during the study period were included in the study . patients were interviewed for relevant information and their quality of life was assessed during the first visit and 8 weeks after the last visit . results . a total of 76 patients were included in this study . final diagnosis and treatment plan were established as part of the telecardiology consultations in 71.1 % and 77.3 % of patients , respectively . patients ' travel was avoided for 38 ( 50.0 % ) who were managed locally . the majority of patients perceived that the visit to the telecardiology clinic results in less travel time ( 96.1 % ) , less waiting time ( 98.1 % ) , and lower cost ( 100.0 % ) . telecardiology consultations resulted in an improvement in the quality of life after two months of the first visit . conclusions . telecardiology care in remote areas of jordan would improve the access to health care , help to reach proper diagnosis and establish the treatment plan , and improve the quality of life ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: congenital hernia of the umbilical cord is a different type of ventral abdominal wall defect , in which the bowel usually herniates into the base of normally inserted umbilical cord through a patent umbilical ring . its incidence is estimated to be 1 in 5000 , and unlike omphalocele , it is not linked with chromosomal anomalies , and association with other anomalies is rare although there is a loose association with intestinal anomalies , malrotation , and volvulus . cases of umbilical cord hernia associated with extracelomic colonic atresia , short gut , and patent omphalomesenteric duct ( omd ) were reported . a term male newborn , weighing 2480 g , was born by spontaneous vaginal delivery at the 37 gestation week . the prenatal events were normal , and anomaly was not diagnosed during the pregnancy although antenatal ultrasound scans were performed . at first , the patient was thought to have small omphalocele ; however , careful examination revealed hernia of umbilical cord with prolapsing bowel evisceration through the umbilical cord . further examinations showed that there were no other associated anomalies , and genetic screening was normal . the patient was given initial resuscitation in terms of covering the bowel with warm saline soaked gauzes , infusing intravenous fluids , and prophylactic antibiotics . the patient was vitally stable , and surgery was performed on the next day . at operation , patent omd was confirmed as extruded mucosa , with openings on both sides where meconium has been passed . first umbilical arteries , vein , and urachus were ligated ; afterward , amniotic membrane was dissected , and reduction of eviscerated mucosa was done [ figure 1a c ] . resection of widely patent omd was performed with end - to - end ileoileal anastomosis . he started on feeding after 72 h. the patient was discharged home on the 17 postoperative day in a good clinical condition . ( b ) intraoperative findings after removing of amniotic sac , small intestines , and omphalomesenteric duct . congenital hernia of the umbilical cord is a herniation of small bowel and occasionally other viscera into umbilical cord while the rest of the anterior abdominal wall is usually normal . during the 3 week of intrauterine life , there is a communication between the intraembryonic gut and the yolk sac as the development proceeds this communication narrows into a tube known as the omd , and it usually obliterates by the end of the 7 week . there is physiological herniation of the midgut into the umbilical coelom during 56 week of gestation and herniated gut then returns during 1012 week of gestation into the abdominal cavity . it is the time when a small part of midgut could not return completely into the abdomen and thus retained in the base of umbilicus resulting in hernia of umbilical cord . last decades , antenatal diagnosis of hernia of umbilical cord was reported on prenatal ultrasound and magnetic resonance imaging findings . for correct clinical diagnostics , it is mandatory to look carefully for the presence of any true abdominal wall defect , umbilical ring , and the basis for the presence of skin collar fold so that the condition could not be misdiagnosed . any unusual thickening of the base of the cord along with even the most minute fistula opening to its side should alert the physician to the existence of these combined anomalies . if this is misdiagnosed , clamping of the umbilical cord after birth can cause iatrogenic atresia of the ileum .\noutput:\n" }, { "from": "agent", "value": "congenital hernia of the cord is a different type of ventral abdominal wall defect in which the bowel usually herniates into the base of normally inserted umbilical cord through a patent umbilical ring . it is rare congenital anomaly with incidence of 1 in 5000 . although it was described as a distinct entity since 1920s it is often misdiagnosed as a small omphalocele . we present an unusal case of term male newborn with umbilical cord hernia associated with patent omphalomesenteric duct . the diagnose was made after birth despite antenatal ultrasound scans and it is managed successfully with uneventful recovery . if this is missdiagnosed , it could cause iatrogenic atresia of the ileum by clamping the umbilical cord after birth ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: a 5 % random sample of all medicare claims were obtained from the denominator files provided by the centers for medicare and medicaid services . the 5 % sample was created based on selecting records with 05 , 20 , 45 , 70 , or 95 in positions 8 and 9 of the health insurance claim number . for inclusion in thiscohort patients had a diagnosis code for nafld [ the international classification of diseases , ninth revision ( icd - 9 ) codes of 571.8 as nafld without mention of alcohol or 571.9 as unspecified chronic liver disease ] . further , patients had to have at least 12 months ( or until death ) of continuous enrollment in medicare part a and b. patients were excluded if they had other chronic liver diseases without nafld [ 070 viral hepatitis ; 155.0 and 155.2 hcc ; 155.2 cholangiocarcinoma ; 275.0 disorders or iron metabolism ; 570 acute and subacute necrosis of liver ; 571.0 alcoholic liver disease ; 571.1 acute alcoholic hepatitis ; 571.2 alcoholic cirrhosis of liver ; 571.3 alcoholic liver damage , unspecified ; 571.4 chronic hepatitis ( including 571.42 autoimmune hepatitis ) ; 571.6 biliary cirrhosis ; 573.3 toxic hepatitis ; 573.8 hepatoptosis ] , cancer codes 140 to 209 , human immunodeficiency virus infection code 042 , or renal disorders ( 582 chronic glomerulonephritis code ; 585 chronic kidney disease ; 586 renal failure ; v42 .0 kidney transplant ; v45 .1 renal dialysis ; v56 encounter for dialysis and dialysis catheter care ) ; or incurred a negative charge . for more details on inpatient inclusion see figure 1 and for outpatient see figure 2 . icd - 9 code for health conditions were considered to be always present if they were coded at least once . the total provider payments were calculated as the sum of medicare reimbursement amount plus the primary insurance payment plus the beneficiary - paid amounts ( copay and deductibles ) . for the time - varying variables , for example , total health care charges vary by claim , so we created a variable for each beneficiary representing annual total health care charges for each claim : further , an average annual charge was calculated by dividing annual total charges by annual total health care visits . the following variables were available : the following 7 diagnoses were also considered covariates and were identified using any of the up to 10 listed icd codes : ( 1 ) hepatic cirrhosis was identified by icd - 9 code 571.5 as hepatic cirrhosis without mention of alcohol ; ( 2 ) decompensated cirrhosis ( dcc ) codes 789.5 as ascites , 567.23 as spontaneous bacterial peritonitis , 456.0 as esophageal varices with bleeding , 456.2 as esophageal varices in disease classified elsewhere , code underlying cause are cirrhosis of liver and portal hypertension , and 572.2 as hepatic encephalopathy ; ( 3 ) cardiovascular disease ( cvd ) codes 410 , 412 as myocardial infarction , 398.91 , 402.01 , 402.11 , 402.91 , 404.01 , 404.03 , 404.11 , 404.13 , 404.91 , 404.93 , 425.4 - 425.9 , 428 as congestive heart failure , 093.0 , 437.3 , 440 , 441 , 443.1 - 443.9 , 447.1 , 557.1 , 557.9 , 43.4 as peripheral vascular disease , 362.34 , 430 - 438 as cerebrovascular disease ;( 4 ) diabetes code 250 ; ( 5 ) hypertension codes 401 - 405 ; ( 6 ) hyperlipidemia codes 272.0 - 272.2 , and 272.4 ; and ( 7 ) obesity codes 278.00 , 278.01 , v85 .3 , v85 .4 . study characteristics are presented with interquartile ranges ( iqrs ) for continuous variables or proportions for categorical variables . descriptive characteristics were compared between nafld with compensated cirrhosis ( cc ) and dcc by t test for numerical variables and tests for categorical variables . log - linked - generalized regression was used to generate coefficients with p - values for each highly skewed outcome variables . to separately describe the amount of increases and decreases in annual total charges / payments associated with a unit change in the explanatory variable for inpatient care cohort and in outpatient care cohort , , we analyzed the causes of hospitalizations among patients with nafld , according to the presence or absence of cirrhosis . in order to minimize a misclassification bias , we further narrowed the inpatient population to patients with nafld , where nafld was primary , secondary or tertiary diagnosis , and analyzed the leading causes of hospitalization again . finally , using the primary icd - 9 diagnosis code , we selected the following conditions : nafld , nonalcoholic hepatic cirrhosis , hepatic encephalopathy , portal hypertension , esophageal varices with / without bleeding , ascites , and spontaneous bacterial peritonitis as nafld - related inpatient / outpatient utilization . this is a retrospective cohort study pertaining to medicare claims among inpatients and outpatients during 2010 . medicare is a us government sponsored health insurance program for us residents aged 65 years and older , for younger patients with disabilities and those with end - stage renal disease or amyotrophic lateral sclerosis . a 5 % random sample of all medicare claims were obtained from the denominator files provided by the centers for medicare and medicaid services . the 5 % sample was created based on selecting records with 05 , 20 , 45 , 70 , or 95 in positions 8 and 9 of the health insurance claim number . for inclusion in thiscohort patients had a diagnosis code for nafld [ the international classification of diseases , ninth revision ( icd - 9 ) codes of 571.8 as nafld without mention of alcohol or 571.9 as unspecified chronic liver disease ] . further , patients had to have at least 12 months ( or until death ) of continuous enrollment in medicare part a and b. patients were excluded if they had other chronic liver diseases without nafld [ 070 viral hepatitis ; 155.0 and 155.2 hcc ; 155.2 cholangiocarcinoma ; 275.0 disorders or iron metabolism ; 570 acute and subacute necrosis of liver ; 571.0 alcoholic liver disease ; 571.1 acute alcoholic hepatitis ; 571.2 alcoholic cirrhosis of liver ; 571.3 alcoholic liver damage , unspecified ; 571.4 chronic hepatitis ( including 571.42 autoimmune hepatitis ) ; 571.6 biliary cirrhosis ; 573.3 toxic hepatitis ; 573.8 hepatoptosis ] , cancer codes 140 to 209 , human immunodeficiency virus infection code 042 , or renal disorders ( 582 chronic glomerulonephritis code ; 585 chronic kidney disease ; 586 renal failure ; v42 .0 kidney transplant ; v45 .1 renal dialysis ; v56 encounter for dialysis and dialysis catheter care ) ; or incurred a negative charge . for more details on inpatient inclusion see figure 1 and for outpatient see figure 2 . icd - 9 code for health conditions were considered to be always present if they were coded at least once . the total provider payments were calculated as the sum of medicare reimbursement amount plus the primary insurance payment plus the beneficiary - paid amounts ( copay and deductibles ) . for the time - varying variables , for example , total health care charges vary by claim , so we created a variable for each beneficiary representing annual total health care charges for each claim : further , an average annual charge was calculated by dividing annual total charges by annual total health care visits . the following variables were available : the following 7 diagnoses were also considered covariates and were identified using any of the up to 10 listed icd codes : ( 1 ) hepatic cirrhosis was identified by icd - 9 code 571.5 as hepatic cirrhosis without mention of alcohol ; ( 2 ) decompensated cirrhosis ( dcc ) codes 789.5 as ascites , 567.23 as spontaneous bacterial peritonitis , 456.0 as esophageal varices with bleeding , 456.2 as esophageal varices in disease classified elsewhere , code underlying cause are cirrhosis of liver and portal hypertension , and 572.2 as hepatic encephalopathy ; ( 3 ) cardiovascular disease ( cvd ) codes 410 , 412 as myocardial infarction , 398.91 , 402.01 , 402.11 , 402.91 , 404.01 , 404.03 , 404.11 , 404.13 , 404.91 , 404.93 , 425.4 - 425.9 , 428 as congestive heart failure , 093.0 , 437.3 , 440 , 441 , 443.1 - 443.9 , 447.1 , 557.1 , 557.9 , 43.4 as peripheral vascular disease , 362.34 , 430 - 438 as cerebrovascular disease ; ( 4 ) diabetes code 250 ; ( 5 ) hypertension codes 401 - 405 ; ( 6 ) hyperlipidemia codes 272.0 - 272.2 , and 272.4 ; and ( 7 ) obesity codes 278.00 , 278.01 , v85 .3 , v85 .4 . study characteristics are presented with interquartile ranges ( iqrs ) for continuous variables or proportions for categorical variables . descriptive characteristics were compared between nafld with compensated cirrhosis ( cc ) and dcc by t test for numerical variables and tests for categorical variables . log - linked - generalized regression was used to generate coefficients with p - values for each highly skewed outcome variables . to separately describe the amount of increases and decreases in annual total charges / payments associated with a unit change in the explanatory variable for inpatient care cohort and in outpatient care cohort , , we analyzed the causes of hospitalizations among patients with nafld , according to the presence or absence of cirrhosis . in order to minimize a misclassification bias , we further narrowed the inpatient population to patients with nafld , where nafld was primary , secondary or tertiary diagnosis , and analyzed the leading causes of hospitalization again . finally , using the primary icd - 9 diagnosis code , we selected the following conditions : nafld , nonalcoholic hepatic cirrhosis , hepatic encephalopathy , portal hypertension , esophageal varices with / without bleeding , ascites , and spontaneous bacterial peritonitis as nafld - related inpatient / outpatient utilization . after applying strict inclusion and exclusion criteria , between january 1 , 2010 and december 31 , 2010 , we were able to include 976 nafld patients who received care in the inpatient setting while 4742 nafld patients sought care in the outpatient setting ( figs . 1 and 2 ) . overall , approximately 87 % were white , 36 % were male , and nearly 30 % had cvd or metabolic syndrome conditions ( dm , hypertension , hyperlipidemia ) ( table 1 ) . of the entire nafld cohort , characteristics of study by cirrhosis status , inpatient and outpatient medicare , 2010 among nafld inpatients , the median annual total hospital charges were $ 36,289 ( iqr : $ 18,359 - $ 71,225 ] ( table 1 ) . as expected , total charges for the nafld patients without cirrhosis were significantly lower than those for nafld patients with cirrhosis ( $ 33,863 vs. $ 61,151 ; p 0.001 ) . furthermore , charges for the nafld patients with dcc were significantly higher than patients with cc ( $ 66,554 vs. $ 34,860 ; p = 0.019 ) ( table 2 ) . in multivariate adjusted analyses , inpatient mortality ( 258 % , p 0.001 ) , presence of cc ( 90 % , p 0.001 ) , and presence of cvd ( 51 % , p 0.001 ) were associated with increased inpatient total charges ( table 3 ) . characteristics of study by cirrhosis type , inpatient and outpatient medicare , 2010 multivariate adjusted associations of hospital utilization with covariates among medicare beneficiaries with nafld , inpatient and outpatient medicare , 2010 among inpatients with nafld , the median annual total payment was $ 11,043 ( iqr : $ 6,103 - $ 21,345 ) . again , for nafld patients without cirrhosis , total payment was significantly lower compared with patients with advanced disease ( $ 10,146 vs. $ 18,804 , p 0.001 ) ( table 1 ) . furthermore , nafld patients with dc had approximately $ 8000 higher annual total hospital payment than nafld with cc ( $ 19,767 vs. $ 11,699 , p = 0.018 ) ( table 2 ) . in multivariate analyses , inpatient mortality ( 148 % , p 0.001 ) , presence of dc ( 89 % , p 0.001 ) , and presence of cvd ( 53 % , p 0.001 ) were again associated with increased total inpatient payment ( table 3 ) . the median annual total outpatient care charge was $ 9,011 ( $ 4,030 - $ 18,577 ) for patients with nafld for a total of 6 outpatient visits ( range : 3 to 11 ) ( table 1 ) . compared with nafld patients with cirrhosis , nafld patients without cirrhosis had significantly lower outpatient charges ( $ 8,830 vs. $ 12,049 , p 0.001 ) . similar to the inpatient setting , total charges increased in the outpatient setting in parallel to the severity of the liver disease . patients with dcc had approximately a $ 5,000 higher charges than patients with cc ( $ 15,187 vs. $ 10,379 , p = 0.043 ) ( table 2 ) . in multivariate adjusted analyses , presence of cvd ( 66 % ) , hypertension ( 61 % ) , and obesity ( 53 % , all p 0.001 ) were associated with increased outpatient charges ( table 3 ) . among nafld patients , the median total annual outpatient care payment was $ 1,777 ( $ 785 - $ 4,043 ) ( table 1 ) . again , nafld patients without cirrhosis had significantly lower payments than nafld patients with cirrhosis ( $ 1,734 vs. $ 2,586 , p 0.001 ) . although nafld patients with dcc had higher payments than patients with cc , it was not statistically significant ( $ 2,701 vs. $ 2,389 , p = 0.34 ) ( table 2 ) . similar to outpatient charges , presence of cvd ( 62 % ) , hypertension ( 61 % ) , and obesity ( 52 % , all p 0.001 ) were associated with increased outpatient payments in nafld patients with medicare ( table 3 ) . in order to assess the nafld - related resource utilization more clearly , we selected inpatients and outpatients where nafld and related diseases ( cryptogenic cirrhosis , etc . ) were the primary diagnosis . in addition , in order to exclude the impact on an expensive confounder , we excluded patients with cvd ( table 4 ) . as expected , the number of patients in each group was smaller than the original analysis . compared with the total cohort , total cumulative charges ( $ 74,276 vs. $ 36,289 ) and payments ( $ 20,450 vs. $ 11,043 ) almost doubled in this nafld - related analysis in the inpatient setting . in contrast , total cumulative charges ( $ 6390 vs. $ 9011 ) and payments ( $ 1400 vs. $ 1777 ) were found to be slightly lower in the nafld - related analysis as compared with total cohort in the outpatient setting . charges and payments of inpatients and outpatients with nafld , where nafld and related diseases ( cryptogenic cirrhosis , etc . ) are the primary diagnosis in the absence of cvd we also analyzed the leading causes of hospitalizations among total inpatient cohort . in patients with the diagnosis of cirrhosis , hepatic encephalopathy ( 16 % ) was the most common diagnosis , followed by the diagnosis of cryptogenic cirrhosis and the diagnostic code for nafld . in the cohort without diagnosis of cirrhosis , the most common diagnoses leading to hospitalization were acute pancreatitis , morbid obesity , and pneumonia . in order to assess nafld - related hospitalizations more clearly , we reanalyzed the data for inpatients where nafld was the primary , secondary or tertiary diagnoses . this reanalysis showed that in those who were admitted with diagnosis of cirrhosis , nafld ( 16 % ) and hepatic encephalopathy ( 14 % ) were the most common diagnoses , followed by chronic bronchitis . in contrast , in patients who were hospitalized without cirrhosis , acute pancreatitis remained the leading cause of hospitalization , followed by morbid obesity and acute bronchitis . among nafld inpatients , the median annual total hospital charges were $ 36,289 ( iqr : $ 18,359 - $ 71,225 ] ( table 1 ) . as expected , total charges for the nafld patients without cirrhosis were significantly lower than those for nafld patients with cirrhosis ( $ 33,863 vs. $ 61,151 ; p 0.001 ) . furthermore , charges for the nafld patients with dcc were significantly higher than patients with cc ( $ 66,554 vs. $ 34,860 ; p = 0.019 ) ( table 2 ) . in multivariate adjusted analyses , inpatient mortality ( 258 % , p 0.001 ) , presence of cc ( 90 % , p 0.001 ) , and presence of cvd ( 51 % , p 0.001 ) were associated with increased inpatient total charges ( table 3 ) . characteristics of study by cirrhosis type , inpatient and outpatient medicare , 2010 multivariate adjusted associations of hospital utilization with covariates among medicare beneficiaries with nafld , inpatient and outpatient medicare , 2010 among inpatients with nafld , the median annual total payment was $ 11,043 ( iqr : $ 6,103 - $ 21,345 ) . again , for nafld patients without cirrhosis , total payment was significantly lower compared with patients with advanced disease ( $ 10,146 vs. $ 18,804 , p 0.001 ) ( table 1 ) . furthermore , nafld patients with dc had approximately $ 8000 higher annual total hospital payment than nafld with cc ( $ 19,767 vs. $ 11,699 , p = 0.018 ) ( table 2 ) . in multivariate analyses , inpatient mortality ( 148 % , p 0.001 ) , presence of dc ( 89 % , p 0.001 ) , and presence of cvd ( 53 % , p 0.001 ) were again associated with increased total inpatient payment ( table 3 ) . the median annual total outpatient care charge was $ 9,011 ( $ 4,030 - $ 18,577 ) for patients with nafld for a total of 6 outpatient visits ( range : 3 to 11 ) ( table 1 ) . compared with nafld patients with cirrhosis , nafld patients without cirrhosis had significantly lower outpatient charges ( $ 8,830 vs. $ 12,049 , p 0.001 ) . similar to the inpatient setting , total charges increased in the outpatient setting in parallel to the severity of the liver disease . patients with dcc had approximately a $ 5,000 higher charges than patients with cc ( $ 15,187 vs. $ 10,379 , p = 0.043 ) ( table 2 ) . in multivariate adjusted analyses , presence of cvd ( 66 % ) , hypertension ( 61 % ) , and obesity ( 53 % , all p 0.001 ) were associated with increased outpatient charges ( table 3 ) . among nafld patients , the median total annual outpatient care payment was $ 1,777 ( $ 785 - $ 4,043 ) ( table 1 ) . again , nafld patients without cirrhosis had significantly lower payments than nafld patients with cirrhosis ( $ 1,734 vs. $ 2,586 , p 0.001 ) . although nafld patients with dcc had higher payments than patients with cc , it was not statistically significant ( $ 2,701 vs. $ 2,389 , p = 0.34 ) ( table 2 ) . similar to outpatient charges , presence of cvd ( 62 % ) , hypertension ( 61 % ) , and obesity ( 52 % , all p 0.001 ) were associated with increased outpatient payments in nafld patients with medicare ( table 3 ) . in order to assess the nafld - related resource utilization more clearly , we selected inpatients and outpatients where nafld and related diseases ( cryptogenic cirrhosis , etc . ) were the primary diagnosis . in addition , in order to exclude the impact on an expensive confounder , we excluded patients with cvd ( table 4 ) . as expected , the number of patients in each group was smaller than the original analysis . compared with the total cohort , total cumulative charges ( $ 74,276 vs. $ 36,289 ) and payments ( $ 20,450 vs. $ 11,043 ) almost doubled in this nafld - related analysis in the inpatient setting . in contrast , total cumulative charges ( $ 6390 vs. $ 9011 ) and payments ( $ 1400 vs. $ 1777 ) were found to be slightly lower in the nafld - related analysis as compared with total cohort in the outpatient setting . charges and payments of inpatients and outpatients with nafld , where nafld and related diseases ( cryptogenic cirrhosis , etc . ) are the primary diagnosis in the absence of cvdwe also analyzed the leading causes of hospitalizations among total inpatient cohort . in patients with the diagnosis of cirrhosis , hepatic encephalopathy ( 16 % ) was the most common diagnosis , followed by the diagnosis of cryptogenic cirrhosis and the diagnostic code for nafld . in the cohort without diagnosis of cirrhosis , the most common diagnoses leading to hospitalization were acute pancreatitis , morbid obesity , and pneumonia . in order to assess nafld - related hospitalizations more clearly , we reanalyzed the data for inpatients where nafld was the primary , secondary or tertiary diagnoses . this reanalysis showed that in those who were admitted with diagnosis of cirrhosis , nafld ( 16 % ) and hepatic encephalopathy ( 14 % ) were the most common diagnoses , followed by chronic bronchitis . in contrast , in patients who were hospitalized without cirrhosis , acute pancreatitis remained the leading cause of hospitalization , followed by morbid obesity and acute bronchitis . nafld is a growing health problem around the world , affecting patients and the society not only with its clinical consequences , but also with its economic burden . although nafld impacts all age groups , the prevalence of nafld increases with age ,14 making it especially pertinent to the medicare services in the united states . our study showed that medicare patients with nafld posed substantial inpatient and outpatient health care utilization . as liver disease progressed to cirrhosis and its complications , the total charges and payments from medicare in both the inpatient and outpatient setting increased . in fact , nafld with dcc was associated with higher costs , with 90 % and 70 % increases for total charge and payment in the inpatient setting , and 46 % and 13 % increases in the outpatient setting , when compared with noncirrhotic nafld patients . in addition to the actual cost per patient , the total number of patients with nafld in the united states can make these costs potentially enormous . further , approximately 10 % to 12 % of these patients will transition to a more severe disease state , nash , which can then progress to cirrhosis . the findings of this study were in agreement with previous studies that reported the increased resource utilization among nafld patients .1820 in a recent study among outpatients with nafld who were medicare beneficiaries , it was found that the annual average charge and payment significantly increased between 2005 and 2010 . the outpatient charge increased nearly a thousand dollars , with an annual increase rate of 5 % .18 this is an important finding indicating not only an increasing prevalence of nafld but also an increase in the cost of each patient with nafld over the study time period . in another study , baumeister et al19 investigated the cost of presumed fatty liver in the inpatient and outpatient setting . the authors concluded that compared with those with normal liver echogenity and normal levels of alt , presence of liver hyperechogenity with elevated alt levels increased overall costs 32 % , with a 15 % increase in outpatient costs and a 38 % in inpatient costs . in our study , in order to assess resource utilization caused by nafld more clearly , we reanalyzed the total cohort and selected inpatient and outpatient groups where nafld and other related diagnostic codes ( nafld - related cirrhosis , hepatic encephalopathy , portal hypertension , etc . ) were the primary diagnosis . from one of the subanalysis , we excluded an important confounder associated with nafld which could be driving the cost ( cvd ) . these reanalyses showed that total charges and payments almost doubled for inpatients when nafld - related conditions were the primary diagnosis in comparison to the total cohort . on the contrary , in the outpatient settingthese data suggest that when nafld is the primary diagnosis in the inpatient setting , these patients have more severe disease accounting for the higher costs . it is also important to remember that most patients with nafld are asymptomatic and undiagnosed . in this context , a large number of these patients may silently progress and then present with cirrhosis for liver transplantation or present with the diagnosis of advanced hcc .12,21,22 presence of cirrhosis is important because the median survival of cc is about 6.5 years , which falls to 2.5 years for those in the decompensated stage .23,24 in our study , 22 % of inpatient and 14 % of outpatient nafld patients with dcc died during the study period of only 12 months , whereas these rates were 9 % and 1.7 % in patients with cc , respectively . in addition to the high mortality , cirrhotic patients are known to have significant morbidities such as variceal bleeding , ascites and hepatic encephalopathy which could lead to not only increased resource utilization but also significant negative impact on patients health - related quality of life .25 our study also confirmed the strong association between nafld and the risk of cvd . previous studies reported that the prevalence of coronary , cerebrovascular and peripheral vascular disease were remarkably higher among patients with nafld .2628 in our study , cvd was an important driver of resource utilization . in fact , in medicare patients with nafld , presence of cvd was an independent predictor of charges and payments in both inpatient and outpatient settings , with 50 % increase in inpatients charges and payments , and 60 % in the outpatient setting . in addition to cvd , our study also confirmed the close association of nafld with metabolic syndrome components and obesity . in fact , among nafld patients with cc , 65 % had hypertension and nearly 60 % had diabetes . similar to cvd , in multivariate analysis , presence of these comorbidities was found to increase inpatient and outpatient charges and payments in different rates . obesity was another factor for increased resource utilization increasing total outpatient charges and payments by 50 % . in fact , as a future projection , finkelstein et al29 reported that obesity prevalence will be 42 % in the year 2030 and if it remained at 2010 levels , nearly $ 440 billion in medical expenditures would be saved in the next 2 decades . these findings are in agreement with the study by ghamar chehreh et al , 30 showing the average treatment cost of nafld patients with obesity and hypertension was higher than for treatment of nafld patients without metabolic conditionsfirst , because of lack of accessibility of recent data , we utilized inpatient and outpatient data for the year 2010 only . by limiting the study period to a year , we were unable to make estimations about the changing pattern of the economic burden of nafld , as noted in other publications .18,31 second , although charges and payments for procedures , imaging and other costs were included in the total amounts , we were unable to itemize individual amounts of these procedures among cirrhotic and noncirrhotic nafld patients . also , as this was a retrospective study on medicare database , we could not determine if patients utilized any type of healthcare plan other than medicare , which may have changed our findings . finally , we used icd - 9 coding and a very strict criteria to select our study cohort . although this approach assured us that we have only patients with nafld , it certainly may have underestimated the number of nafld patients with medicare . in summary , nafld is associated with a significant economic burden to medicare . presence of dc due to nafld is associated with more resource utilization compared with cc and noncirrhotic nafld patients . it can be suggested that as long as the prevalence of obesity and nafld continue to grow , this economic burden of nafld on medicare expenditures will continue to rise .\noutput:\n" }, { "from": "agent", "value": "background : nonalcoholic fatty liver disease ( nafld ) is one of the leading causes of chronic liver disease worldwide with tremendous clinical burden . the economic burden of nafld is not well studied.goal : to assess the economic burden of nafld.study : medicare beneficiaries ( january 1 , 2010 to december 31 , 2010 ) with nafld diagnosis by international classification of diseases , ninth revision codes in the absence of other liver diseases were selected . inpatient and outpatient resource utilization parameters were total charges and total provider payments . nafld patients with compensated cirrhosis ( cc ) were compared with decompensated cirrhosis ( dc ) . results : a total of 976 inpatients and 4742 outpatients with nafld were included87 % were white , 36 % male , 30 % had cardiovascular disease ( cvd ) or metabolic syndrome conditions , and 12 % had cirrhosis . for inpatients , median total hospital charge was $ 36,289 . nafld patients with cirrhosis had higher charges and payments than noncirrhotic nafld patients ( $ 61,151 vs. $ 33,863 and $ 18,804 vs. $ 10,146 , p < 0.001 ) . compared with cc , nafld patients with dc had higher charges and payments ( p < 0.02 ) . for outpatients , median total charge was $ 9,011 . nafld patients with cirrhosis had higher charges and payments than noncirrhotic nafld patients ( $ 12,049 vs. $ 8,830 and $ 2,586 vs. $ 1,734 , p < 0.001 ) . compared with cc , dc patients had higher total charges ( $ 15,187 vs. $ 10,379 , p = 0.04 ) . in multivariate analysis , variables associated with increased inpatient resource utilization were inpatient mortality , dc , and cvd ; for outpatients , having cvd , obesity , and hypertension ( all p < 0.001 ) . conclusions : nafld is associated with significant economic burden to medicare . presence of cirrhosis and cvd are associated with increased resource utilization ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: relapsing polychondritis ( rp ) is a rare but life - threatening disease , which affects caltilaginous and proteoglycan - rich structures such as ears , nose , respiratory tract , and sclera .1 ocular manifestations are present in 50 % 60 % of the cases of rp .1 however , there are a variety of inflammatory symptoms and little specificity is present that can help in diagnosing rp . we report our findings in two patients with rp and with different types of ocular inflammation . a 35 - year - old man who had bilateral hyperemic conjunctiva and ocular pain visited a private clinic in december 2007 . he was diagnosed with episcleritis , and steroids and antibiotic eye drops were prescribed , but the signs and symptoms did not improve . in january 2008 , he began a treatment of 20 mg / day oral prednisolone and was referred to the chiba university hospital in february 2008 . at his first visit , his visual acuity was 1.2 ou , and the intraocular pressure was 20 mmhg ou . slit - lamp examinations showed hyperemic episcleral vessels in both eyes but no inflammatory signs in the anterior chamber ( figure 1 ) . the blood tests showed an elevation of white blood cells count ( 16,300 / l ) , but c - reactive protein ( crp ) was 0.1 mg / dl . the dosage of 15 mg / day oral prednisolone was continued . during the tapering of the oral prednisolone , he developed tinnitus , vertigo , deafness , and left auricular deformation . positron emission tomography identified a mild accumulation of 18f - fluorodeoxyglucose in the left auricle . in january 2009 , an auricular biopsy was performed , and an infiltration of inflammatory cells was detected in and around the cartilagenous tissues . in february 2009 , visual field defects were detected bilaterally , namely , right enlargement of mariotte blind spot and left mild central scotoma . fluorescein angiography revealed hyperfluorescence of both optic disks but vasculitis was not found ( figure 2 ) . the presence of chondritis of the auricles , ocular inflammation ( scleritis ) , and neurosensory hearing loss combined with the histologic findings led to the final diagnosis of rp . systemic examinations showed no abnormal signs in the respiratory tract , heart , and kidney . the oral prednisolone was increased to 30 mg / day beginning in february 2009 , and after a slow tapering , the oral prednisolone treatment was completed in july 2012 . the scleritis was improved , and the visual acuities were 1.2 ou at the last visit in september 2014 . a 71 - year - old man had age - related macular degeneration and had been treated by an intravitreal injection of antivascular endothelial growth factor antibody in another hospital . three months later ( november 2013 ) , he noticed that he was deaf in both ears . at the same time , he developed bilateral scleritis , which was improved by topical steroids . on january 2014 , he had a reddish swelling on the left eyelid and was referred to the chiba university hospital . he had undergone cataract surgeries on both eyes in 2011 and nd - yag laser in 2012 . at the first visit , the intraocular pressures were 7 mmhg on the right and 17 mmhg on the left . the left conjunctiva was hyperemic , but no inflammation was found in both anterior chambers ( figure 3 ) . fundus examinations found late - phase age - related macular degeneration in the left eye . computed tomography showed no sinusitis , but the fat density on the upper surface of the eye was increased ( figure 4 ) . blood tests revealed an elevation of white blood cells ( 11,100 / l ) , the erythrocyte sedimentation rate ( 69 mm / h ) , and the crp to 8.7 mg / dl . the left orbital cellulitis rapidly improved but he developed right scleritis and left gonitis ( figure 5 ) . a second blood test showed an elevation of erythrocyte sedimentation rate and crp and positive antinuclear antibodies . magnetic resonance imaging showed bilateral posterior scleritis and right auricular perichondritis ( figure 5 ) . because he had auricular perichondritis and cochleovestibular disorders on january 30 , 2014 , an auricular biopsy was performed . an infiltration of lymphocytes into the periauricular tissue was found histologically ( figure 6 ) . from these findingssystemic examinations revealed no abnormalities of the respiratory tract , heart , and kidney , but he had the myelodysplastic syndrome . approximately 40 mg / day oral prednisolone was given by a consulting rheumatologist , and both ocular and auricular inflammation improved . he was continued with 10 mg / day oral prednisolone , and his visual acuity at the last examination in july 2014 remained unchanged . a 35 - year - old man who had bilateral hyperemic conjunctiva and ocular pain visited a private clinic in december 2007 . he was diagnosed with episcleritis , and steroids and antibiotic eye drops were prescribed , but the signs and symptoms did not improve . in january 2008 , he began a treatment of 20 mg / day oral prednisolone and was referred to the chiba university hospital in february 2008 . at his first visit , his visual acuity was 1.2 ou , and the intraocular pressure was 20 mmhg ou . slit - lamp examinations showed hyperemic episcleral vessels in both eyes but no inflammatory signs in the anterior chamber ( figure 1 ) . the blood tests showed an elevation of white blood cells count ( 16,300 / l ) , but c - reactive protein ( crp ) was 0.1 mg / dl . the dosage of 15 mg / day oral prednisolone was continued . during the tapering of the oral prednisolone , he developed tinnitus , vertigo , deafness , and left auricular deformation . positron emission tomography identified a mild accumulation of 18f - fluorodeoxyglucose in the left auricle . in january 2009 , an auricular biopsy was performed , and an infiltration of inflammatory cells was detected in and around the cartilagenous tissues . in february 2009 , visual field defects were detected bilaterally , namely , right enlargement of mariotte blind spot and left mild central scotoma . fluorescein angiography revealed hyperfluorescence of both optic disks but vasculitis was not found ( figure 2 ) . the presence of chondritis of the auricles , ocular inflammation ( scleritis ) , and neurosensory hearing loss combined with the histologic findings led to the final diagnosis of rp . systemic examinations showed no abnormal signs in the respiratory tract , heart , and kidney . the oral prednisolone was increased to 30 mg / day beginning in february 2009 , and after a slow tapering , the oral prednisolone treatment was completed in july 2012 . the scleritis was improved , and the visual acuities were 1.2 ou at the last visit in september 2014 . a 71 - year - old man had age - related macular degeneration and had been treated by an intravitreal injection of antivascular endothelial growth factor antibody in another hospital . three months later ( november 2013 ) , he noticed that he was deaf in both ears . at the same time , he developed bilateral scleritis , which was improved by topical steroids . on january 2014 , he had a reddish swelling on the left eyelid and was referred to the chiba university hospital . he had undergone cataract surgeries on both eyes in 2011 and nd - yag laser in 2012 . at the first visit , the intraocular pressures were 7 mmhg on the right and 17 mmhg on the left . the left conjunctiva was hyperemic , but no inflammation was found in both anterior chambers ( figure 3 ) . fundus examinations found late - phase age - related macular degeneration in the left eye . computed tomography showed no sinusitis , but the fat density on the upper surface of the eye was increased ( figure 4 ) . blood tests revealed an elevation of white blood cells ( 11,100 / l ) , the erythrocyte sedimentation rate ( 69 mm / h ) , and the crp to 8.7 mg / dl . the left orbital cellulitis rapidly improved but he developed right scleritis and left gonitis ( figure 5 ) . a second blood test showed an elevation of erythrocyte sedimentation rate and crp and positive antinuclear antibodies . magnetic resonance imaging showed bilateral posterior scleritis and right auricular perichondritis ( figure 5 ) . because he had auricular perichondritis and cochleovestibular disorders on january 30 , 2014 , an auricular biopsy was performed . an infiltration of lymphocytes into the periauricular tissue was found histologically ( figure 6 ) . from these findingssystemic examinations revealed no abnormalities of the respiratory tract , heart , and kidney , but he had the myelodysplastic syndrome . approximately 40 mg / day oral prednisolone was given by a consulting rheumatologist , and both ocular and auricular inflammation improved . he was continued with 10 mg / day oral prednisolone , and his visual acuity at the last examination in july 2014 remained unchanged . mcadam et al were the first to propose the diagnostic criteria for rp in 1976.1 this criteria based on the clinical signs and symptoms include 1 ) bilateral auricular chondritis , 2 ) nonerosive inflammatory polyarthritis , 3 ) nasal chondritis , 4 ) ocular inflammation , 5 ) respiratory tract chondritis , and 6 ) chochlear and / or vestibular damage , resulting in neurosensory hearing loss , tinnitus , and / or vertigo . damiani and levine updated the criteria by adding the histopathologic criteria ,2 which included 1 ) the presence of any three of the mcadam s criteria , 2 ) at least one of the mcadam s criteria confirmed by biopsy , and 3 ) the presence of chondritis in two or more separate anatomic locations with positive response to steroids or dapsone . our cases met one or both criteria and both cases were diagnosed with typical rp . the etiology of rp is still undetermined , but 30 % of patients at the acute phase have increased type ii collagen autoantibodies in their sera . the effectiveness of steroid therapy indicates that rp is probably an idiopathic autoimmune disease . because the ocular findings can be the initial findings of rpisaak et al reported that the most common ocular finding is episcleritis ( 39 % ) and the second is scleritis ( 14 % ) .3 other signs are iritis ( 9 % ) , retinopathy ( 9 % ) , muscle paresis ( 5 % ) , and optic neuritis ( 5 % ) . although case 1 had the typical ocular manifestations , it took 1 year to make the final diagnosis probably because of the wide variety of clinical manifestations . case 2 had ocular cellulitis , and antibiotics were effective , even though it is rare that ocular cellulitis accompanies rp . however , other clinical symptoms are typical and only 3 months were required to make the final diagnosis in this patient . a recent case report reported that multiple myeloma developed 8 years after the diagnosis of rp .4 case 2 also had the myelodysplastic syndrome . thus , a long - term follow - up is required to monitor the development of hematopoietic malignancies .4 although the standard treatment of rp is through the use of steroids , refractory cases require immunosuppressive therapies , eg , cyclosporine ,5 cyclophosphamide ,6 and methotrexate .7 fortunately , in our cases , oral prednisolone was effective with successful tapering without any side effects . rp is a life - threatening disease , and the major mortality arises from infection related to immunosuppression therapies or pneumonia accompanied by laryngotracheal obstruction .8 thus , long - term steroid therapy is needed to lessen the possibility of fatal adverse effects in patients with rp . although ocular and clinical manifestations are not specific , ophthalmologists should consider rp in patients with both ocular and auricular inflammation .\noutput:\n" }, { "from": "agent", "value": "we were presented with two cases of relapsing polychondritis ( rp ) associated with different types of ocular inflammation . the first case was a 35 - year - old man who had bilateral hyperemic conjunctiva and ocular pain , and was referred to chiba university hospital with a diagnosis of episcleritis refractory . he was treated with dexamethasone eye drops . he developed tinnitus , deafness in both ears , and left auriculitis . a left auricular biopsy showed an infiltration of lymphocytes surrounding the cartilage . he was diagnosed with rp and treated with 30 mg / day oral prednisolone . after tapering the prednisolone , the scleritis in both eyes improved . the second case was a 71 - year - old man who was deaf in both ears and had bilateral scleritis . at the first visit to our hospital , his left eyelid and right auricula were reddish and swollen , and he reported some pain . he was treated with intravenous antibiotics , and the left orbital cellulitis quickly improved . however , he developed right scleritis and left gonitis . magnetic resonance imaging showed bilateral posterior scleritis and right auricular perichondritis . auricular biopsy showed an infiltration of lymphocytes into the periauricular tissue . he was diagnosed with rp , and 40 mg / day oral prednisolone was given and his symptoms improved . although rp is rare , it is a life - threatening disease . thus , ophthalmologists should consider rp in patients with both ocular and auricular inflammation ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: since its inception , it has been clear that general relativity has many striking similarities to gauge theories . both are based on the idea of local symmetry and therefore share a number of formal properties . nevertheless , their dynamical behavior can be quite different . while maxwell electrodynamics describes a long - range force similar to the situation with gravity , the non - abelian gauge theories used to describe the weak and strong nuclear forces have rather different behaviors . quantum chromodynamics , which describes the strong nuclear forces , for example , exhibits confinement of particles carrying the non - abelian gauge charges . moreover , consistent quantum gauge theories have existed for a half century , but as yet no satisfactory quantum field theory of gravity has been constructed ; indeed , there are good arguments suggesting that it is not possible to do so . the structures of the lagrangians are also rather different : the non - abelian yang mills lagrangian contains only up to four - point interactions while the einstein - hilbert lagrangian contains infinitely many . despite these differences , string theory teaches us that gravity and gauge theories can , in fact , be unified . the maldacena conjecture , for example , relates the weak coupling limit of a gravity theory on an anti - de sitter backround to a strong coupling limit of a special supersymmetric gauge field theory . there is also a long history of papers noting that gravity can be expressed as a gauging of lorentz symmetry , as well as examples of non - trivial similarities between classical solutions of gravity and non - abelian gauge theo ries . in this reviewa different , but very general , relationship between the weak coupling limits of both gravity and gauge theories will be described . this relationship allows gauge theories to be used directly as an aid for computations in perturbative quantum gravity . the relationship discussed here may be understood most easily from string perturbation theory . at the semi - classical or tree - level , kawai , lewellen , and tye ( klt ) derived a precise set of formulas expressing closed string amplitudes in terms of sums of products of open string amplitudes . in the low - energy limit ( i.e. anywhere well below the string scale of 10 gev ) where string theory effectively reduces to field theory , the klt relations necessarily imply that similar relations must exist between amplitudes in gravity and gauge field theories : at tree - level in field theory , graviton scattering must be expressible as a sum of products of well defined pieces of non - abelian gauge theory scattering amplitudes . moreover , using string based rules , four - graviton amplitudes with one quantum loop in einstein gravity were obtained in a form in which the integrands appearing in the expressions were given as products of integrands appearing in gauge theory . these results may be interpreted heuristically as ( 1 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ gravity \\ ; \\ sim \\ ; ( gauge \\ ; theory ) \\ ; \\ times \\ ; ( gauge \\ ; theory ) . $ $ \\ end { document } this remarkable property suggests a much stronger relationship between gravity and gauge theories than one might have anticipated by inspecting the respective lagrangians . the klt relations hold at the semi - classical level , i. e. with no quantum loops . in order to exploit the klt relations in quantum gravity , one needs to completely reformulate the quantization process ; the standard methods starting either from a hamiltonian or a lagrangian provide no obvious means of exploiting the klt relations . there is , however , an alternative approach based on obtaining the quantum loop contributions directly from the semi - classical tree - level amplitudes by using d - dimensional unitarity . these same methods have also been applied to non - trivial calculations in quantum chromodynamics ( see e.g. refs . ) and in supersymmetric gauge theories ( see e.g. refs . , they provide a means for obtaining collections of quantum loop - level feynman diagrams without direct reference to the underlying lagrangian or hamiltonian . the only inputs with this method are the d - dimensional tree - level scattering amplitudes . an interesting application of this method of perturbatively quantizing gravity is as a tool for investigating the ultra - violet behavior of gravity field theories . the conventional wisdom that quantum field theories of gravity can not possibly be fundamental rests on the apparent non - renormalizability of these theories . simple power counting arguments strongly suggest that einstein gravity is not renormalizable and therefore can be viewed only as a low energy effective field theory . indeed , explicit calculations have established that non - supersymmetric theories of gravity with matter generically diverge at one loop , and pure gravity diverges at two loops . supersymmetric theories are better behaved with the first potential divergence occurring at three loops . however , no explicit calculations have as yet been performed to directly verify the existence of the three - loop supergravity divergences . the method described here for quantizing gravity is well suited for addressing the issue of the ultraviolet properties of gravity because it relates overwhelmingly complicated calculations in quantum gravity to much simpler ( though still complicated ) ones in gauge theories . the first application was for the case of maximally supersymmetric gravity , which is expected to have the best ultraviolet properties of any theory of gravity . this analysis led to the surprising result that maximally supersymmetric gravity is less divergent than previously believed based on power counting arguments . this lessening of the power counting degree of divergence may be interpreted as an additional symmetry unaccounted for in the original analysis . ( the results are inconsistent , however , with an earlier suggestion based on the speculated existence of an unconstrained covariant off - shell superspace for n = 8 supergravity , which in d = 4 implies finiteness up to seven loops . the non - existence of such a superspace was already noted a while ago . ) the method also led to the explicit construction of the two - loop divergence in eleven - dimensional supergravity . more recently , it aided the study of divergences in type i supergravity theories where it was noted that they factorize into products of gauge theory factors . other applications include the construction of infinite sequences of amplitudes in gravity theories . given the complexity of gravity perturbation theory , it is rather surprising that one can obtain compact expressions for an arbitrary number of external legs , even for restricted helicity or spin configurations of the particles . the key for this construction is to make use of previously known sequences in quantum chromodynamics . at tree - level , infinite sequences of maximally helicity violating amplitudes have been obtained by directly using the klt relations and analogous quantum chromodynamics sequences . at one loop , by combining the klt relations with the unitarity method , additional infinite sequences of gravity and super - gravity amplitudes have also been obtained . they are completely analogous to and rely on the previously obtained infinite sequences of one - loop gauge theory amplitudes . these amplitudes turn out to be also intimately connected to those of self - dual yang mills and gravity . the method has also been used to explicitly compute two - loop supergravity amplitudes in dimension d = 11 , that were then used to check m - theory dualities . although the klt relations have been exploited to obtain non - trivial results in quantum gravity theories , a derivation of these relations from the einstein - hilbert lagrangian is lacking . there has , however , been some progress in this regard . it turns out that with an appropriate choice of field variables one can separate the space - time indices appearing in the lagrangian into left andright classes , mimicking the similar separation that occurs in string theory . moreover , with further field redefinitions and a non - linear gauge choice , it is possible to arrange the off - shell three - graviton vertex so that it is expressible in terms of a sum of squares of yang - mills three - gluon vertices . it might be possible to extend this more generally starting from the formalism of siegel , which contains a complete gravity lagrangian with the required factorization of space - time indices . the kawai , lewellen , and tye relations between open and closed string tree amplitudes and their field theory limit are described in section 3 . applications to understanding and constructing tree - level gravity amplitudes are also described in this section . in section 4the implications for the einstein - hilbert lagrangian are presented . the procedure for obtaining quantum loop amplitudes from gravity tree amplitudesthe application of this method to obtain quantum gravity loop amplitudes is described in section 6 . in section 7 the quantum divergence properties of maximally supersymmetric supergravity obtained from this method are described . for a recent review of the status of quantum gravity the reader may consult the article by carlip . the conventional feynman diagram approach to quantum gravity can be found in the les houches lectures of veltman . a review article containing an early version of the method described here of using unitarity to construct complete loop amplitudes is ref . . excellent reviews containing the quantum chromodynamics amplitudes used to obtain corresponding gravity amplitudes are the ones by mangano and parke , and by lance dixon . these reviews also provide a good description of helicity techniques which are extremely useful for explicitly constructing scattering amplitude in gravity and gauge theories . broader textbooks describing quantum chromodynamics are refs . chapter 7 of superstring theory by green , schwarz , and witten contains an illuminating discussion of the relationship of closed and open string tree amplitudes , especially at the four - point level . a somewhat more modern description of string theory may be found in the book by polchinski . applications of string methods to quantum field theory are described in a recent review by schubert . scattering of gravitons in flat space may be described using feynman diagrams . the feynman rules for constructing the diagrams are obtained from the einstein - hilbert lagrangian coupled to matter using standard procedures of quantum field theory . ( the reader may consult any of the textbooks on quantum field theory for a derivation of the feynman rules starting from a given lagrangian . ) for a good source describing the feynman rules of gravity , the reader may consult the classic lectures of veltman . the momentum - space feynman rules are expressed in terms of vertices and propagators as depicted in fig . space - time indices are denoted by i and vi while the momenta are denoted by k or ki . in contrast to gauge theory , gravity has an infinite set of ever more complicated interaction vertices ; the three - and four - point ones are displayed in the figure . the diagrams for describing scattering of gravitons from each other are built out of these propagators and vertices . other particles can be included in this framework by adding new propagators and vertices associated with each particle type . ( for the case of fermions coupled to gravity the lagrangian needs to be expressed in terms of the vierbein instead of the metric before the feynman rules can be constructed . ) figure 1the feynman propagator and three - and four - point vertices in einstein gravity . the feynman propagator and three - and four - point vertices in einstein gravity . according to the feynman rules , each leg or vertex represents a specific algebraic expression depending on the choice of field variables and gauges . for example , the graviton feynman propagator in the commonly used de donder gauge is : ( 2 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { p _ { { \\ mu _ 1 } { \\ nu _ 1 } ;{ \\ mu _ 2 } { \\ nu _ 2 } } } = \\ frac { 1 } { 2 } \\ left [ { { \\ eta _ { { \\ mu _ 1 } { \\ mu _ 2 } } } { \\ eta _ { { \\ mu _ 2 } { \\ nu _ 2 } } } + { \\ eta _ { { \\ mu _ 1 } { \\ nu _ 2 } } } { \\ eta _ { { \\ nu _ 1 } { \\ mu _ 2 } } } - \\ frac { 2 } { { d - 2 } } { \\ eta _ { { \\ mu _ 1 } { \\ nu _ 1 } } } { \\ eta _ { { \\ mu _ 2 } { \\ nu _ 2 } } } } \\ right ] \\ frac { i } { { { k ^ 2 } + i \\ epsilon } } . $ $ \\ end { document } the three - vertex is much more complicated and the expressions may be found in dewitt s articles or in veltman s lectures . for simplicity , only a few of the terms of the three - vertex are displayed : ( 3 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ g _ { de \\ ; donder } ^ { { \\ mu _ 1 } { \\ nu _ 1 } , { \\ mu _ 2 } { \\ nu _ 2 } , { \\ mu _ 3 } { \\ nu _ 3 } } \\ left ( { { k_1 } , { k_2 } , { k_3 } } \\ right ) \\ sim { k_1 } \\ ; 1 } { \\ nu _ 2 } } } + \\ ; many \\ ; other \\ ; terms , $ $ \\ end { document } where the indices associated with each graviton are depicted in the three - vertex of fig . 1 , i. e. , the two indices of graviton i = 1 , 2 , 3 are ii . the loop expansion of feynman diagrams provide a systematic quantum mechanical expansion in planck s constant .2 are interpreted as ( semi ) classical scattering processes while the diagrams with loops are the true quantum mechanical effects : each loop carries with it a power of . according to the feynman rules , each loop represents an integral over the momenta of the intermediate particles . the behavior of these loop integrals is the key for understanding the divergences of quantum gravity . the lines represent any particles in a gravity theory . figure 3sample loop - level feynman diagrams . the lines represent any particles in a gravity theory . sample loop - level feynman diagrams . , the loop momentum integrals in a quantum field theory will diverge in the ultraviolet where the momenta in the loops become arbitrarily large . unless these divergences are of the right formthey indicate that a theory can not be interpreted as fundamental , but is instead valid only at low energies . gauge theories such as quantum chromodynamics are renormalizable : divergences from high energy scales can be absorbed into redefinitions of the original parameters appearing in the theory . in quantum gravity , on the other hand , it is not possible to re - absorb divergences in the original lagrangian for a very simple reason : the gravity coupling \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ k = \\ sqrt { 32 \\ pi { g_n } } $ $ \\ end { document } , where gn is newton s constant , carries dimensions of length ( in units where = c = 1 ) . by dimensional analysis , any divergence must be proportional to terms with extra derivatives compared to the original lagrangian and are thus of a different form . this may be contrasted to the gauge theory situation where the coupling constant is dimensionless , allowing for the theory to be renormalizable . the problem of non - renormalizability of quantum gravity does not mean that quantum mechanics is incompatible with gravity , only that quantum gravity should be treated as an effective field theory for energies well below the planck scale of 10 gev ( which is , of course , many orders of magnitude beyond the reach of any conceivable experiment ) . in an effective field theory , as one computes higher loop orders , new and usually unknown couplings need to be introduced to absorb the divergences . generally , these new couplings are suppressed at low energies by ratios of energy to the fundamental high energy scale , but at sufficiently high energies the theory loses its predictive power . in quantum gravityquantum gravity based on the feynman diagram expansion allows for a direct investigation of the non - renormalizability issue . for a theory of pure gravity with no matter , amazingly , the one - loop divergences cancel , as demonstrated by t hooft and veltman . unfortunately , this result is accidental , since it does not hold generically when matter is added to the theory or when the number of loops is increased . explicit calculations have shown that non - supersymmetric theories of gravity with matter generically diverge at one loop , and pure gravity diverges at two loops . the two - loop calculations were performed using various improvements to the feynman rules such as the background field method . supersymmetric theories of gravity are known to have less severe divergences . in particular , in any four - dimensional supergravity theory , supersymmetry ward identities forbid all possible one - loop and two - loop divergences . there is a candidate divergence at three loops for all supergravities including the maximally extended n = 8 version . however , no explicit three - loop ( super ) gravity calculations have been performed to confirm the divergence . in principle it is possible that the coefficient of a potential divergence obtained by power counting can vanish , especially if the full symmetry of the theory is taken into account . as described in section 7 , this is precisely what does appear to happen in the case of maximally supersymmetric supergravity . the reason no direct calculation of the three - loop supergravity divergences has been performed is the overwhelming technical difficulties associated with multi - loop gravity feynman diagrams . in multi - loop calculationsthe number of algebraic terms proliferates rapidly beyond the point where computations are practical . as a particularly striking example , consider the five - loop diagram in fig .4 , which , as noted in section 7 , is of interest for ultraviolet divergences in maximal n = 8 supergravity in d = 4 . in the standard de donder gauge this diagram contains twelve vertices , each of the order of a hundred terms , and sixteen graviton propagators , each with three terms , for a total of roughly 10 terms , even before having evaluated any integralsthe standard methods for simplifying diagrams , such as background - field gauges and superspace , are unfortunately insufficient to reduce the problem to anything close to manageable levels . the alternative of using string - based methods that have proven to be useful at one - loop and in certain two - loop calculations also does not as yet provide a practical means for performing multi - loop scattering amplitude calculations , especially in gravity theories . the heuristic relation ( 1 ) suggests a possible way to deal with multi - loop diagrams such as the one in fig . since gauge theory feynman rules are inherently much simpler than gravity feynman rules , it clearly would be advantageous to re - express gravity perturbative expansions in terms of gauge theory ones . as a first step , one might , for example , attempt to express the three - graviton vertex as a product of two yang mills vertices , as depicted in fig .5 : ( 4 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ g _ { factorizing } ^ { { \\ mu _ 1 } { \\ nu _ 1 } , { \\ mu _ 2 } { \\ nu _ 2 } , { \\ mu _ 3 } { \\ nu _ 3 } } \\ left ( { { k_1 } , { k_2 } , { k_3 } } \\ right ) \\ sim v _ { ym } ^ { { \\ mu _ 1 } { \\ mu _ 2 } { \\ mu _ 3 } } \\ left ( { { k_1 } , { k_2 } , { k_3 } } \\ right ) \\ ; v _ { ym } ^ { { \\ nu _ 1 } { \\ nu _ 2 } { \\ nu _ 3 } } \\ left ( { { k_1 } , { k_2 } , { k_3 } } \\ right ) , $ $ \\ end { document } where the two indices of each graviton labeled by i = 1 , 2 , 3 are ii , i.e. \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { h _ { { \\ mu _ i } { \\ nu _ i } } } $ $ \\ end { document } . figure 5string theory suggests that the three - graviton vertex can be expressed in terms of products of three - gluon vertices . string theory suggests that the three - graviton vertex can be expressed in terms of products of three - gluon vertices . such relations , however , do not hold in any of the standard formulations of gravity . for example , the three - vertex in the standard de donder gauge ( 3 ) contains traces over gravitons , i. e. a contraction of indices of a single graviton . for physical gravitonsthe traces vanish , but for gravitons appearing inside feynman diagrams it is in general crucial to keep such terms . a necessary condition for obtaining a factorizing three - graviton vertex ( 4 ) is that the left i indices never contract with the right i indices . the standard formulations of quantum gravity generate a plethora of terms that violate the heuristic relation ( 1 ) . in section 4the question of how one rearranges the einstein action to be compatible with string theory intuition is returned to . however , in order to give a precise meaning to the heuristic formula ( 1 ) and to demonstrate that scattering amplitudes in gravity theories can indeed be obtained from standard gauge theory ones , a completely different approach from the standard lagrangian or hamiltonian ones is required . our starting point for constructing perturbative quantum gravity is the kawai , lewellen , and tye ( klt ) relations between closed and open string tree - level amplitudes . since closed string theories are theories of gravity and open string theories include gauge bosons , in the low energy limit , where string theory reduces to field theory , these relations then necessarily imply relations between gravity and gauge theories . the realization that ordinary gauge and gravity field theories emerge from the low energy limit of string theories has been appreciated for nearly three decades . . ) the klt relations between open and closed string theory amplitudes can be motivated by the observation that any closed string vertex operator for the emission of a closed string state ( such as a graviton ) is a product of open string vertex operators ( see e.g. ref . ) , ( 5 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { v ^ { closed } } = v _ { left } ^ { open } \\ ; \\ times \\ ; \\ bar v _ { right } ^ { open } . $ $ \\ end { document } this product structure is then reflected in the amplitudes . indeed , the celebrated koba - nielsen form of string amplitudes , which may be obtained by evaluating correlations of the vertex operators , factorize at the level of the integrands before world sheet integrations are performed . amazingly , kawai , lewellen , and tye were able to demonstrate a much stronger factorization : complete closed string amplitudes factorize into products of open string amplitudes , even after integration over the world sheet variables . ( a description of string theory scattering amplitudes and the history of their construction may be found in standard books on string theory . ) as a simple example of the factorization property of string theory amplitudes , the four - point partial amplitude of open superstring theory for scattering any of the massless modes is given by ( 6 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ a_4 ^ { open } = - \\ frac { 1 } { 2 } { g ^ 2 } \\ frac { { \\ gamma ( \\ alpha ' s ) \\ gamma ( \\ alpha ' t ) } } { { \\ gamma ( 1 + \\ alpha 's + \\ alpha ' t ) } } { \\ xi ^ a } { \\ xi ^ b } { \\ xi ^ c } { \\ xi ^ d } { k _ { abcd } } ( { k_1 } , { k_2 } , { k_3 } , { k_4 } ) , $ $ \\ end { document } where is the open string regge slope proportional to the inverse string tension , g is the gauge theory coupling , and k is a gauge invariant kinematic coefficient depending on the momenta k1 , ... , k4 . ( the metric is taken here to have signature ( + , - , - , - ) . ) in this and subsequent expressions , s = ( k1 + k2 ) , t = ( k1 + k2 ) , and u = ( k1 + k3 ) . the indices can be either vector , spinor or group theory indices and the can be vector polarizations , spinors , or group theory matrices , depending on the particle type . these amplitudes are the open string partial amplitudes before they are dressed with chan - paton group theory factors and summed over non - cyclic permutations to form complete amplitudes . ( 6 ) are associated with string world sheet charges arising from possible compactifications . ) for the case of a vector , is the usual polarization vector . similarly , the four - point amplitudes corresponding to a heterotic closed superstring are ( 7 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { m_4 ^ { closed } = { \\ kappa ^ 2 } \\ sin \\ left ( { \\ frac { { \\ alpha ' \\ pi t } } { 4 } } \\ right ) \\ ; \\ times \\ ; \\ frac { { \\ gamma ( \\ alpha ' s / 4 ) \\ gamma ( \\ alpha ' t / 4 ) } } { { \\ gamma ( 1 + \\ alpha ' s / 4 + \\ alpha ' t / 4 ) } } \\ ; \\ times \\ ; \\ frac { { \\ gamma ( \\ alpha ' t / 4 ) \\ gamma ( \\ alpha ' \\ mu / 4 ) } } { { \\ gamma ( 1 + \\ alpha ' t / 4 + \\ alpha ' \\ mu / 4 ) } } } \\ \\ { \\ times { \\ xi ^ { aa ' } } { \\ xi ^ { bb ' } } { \\ xi ^ { cc ' } } { \\ xi ^ { dd ' } } { k _ { abcd } } _ { ( { k_1 } / 2 , { k_2 } / 2 , { k_3 } / 2 , { k_4 } / 2 ) } \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { \\ times \\ ; { k _ { a ' b ' c ' d' ( { k_1 } / 2 , { k_2 } / 2 , { k_3 } / 2 , { k_4 } / 2 ) } } , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ end { array } $ $ \\ end { document } where is the open string regge slope or equivalently twice the close string one . up to prefactors , the replacements gx and substituting ki ki / 2 , the closed string amplitude ( 7 ) is a product of the open string partial amplitudes ( 6 ) . for further reading , chapter 7 of superstring theory by green , schwarz , and witten provides an especially enlightening discussion of the four - point amplitudes in various string constructions . as demonstrated by klt , the property that closed string tree amplitudes can be expressed in terms of products of open string tree amplitudes is completely general for any string states and for any number of external legs . in general , it holds also for each of the huge number of possible string compactifications . an essential part of the factorization of the amplitudes is that any closed - string state is a direct product of two open - string states . this property directly follows from the factorization of the closed - string vertex operators ( 5 ) into products of open - string vertex operators . in general for every closed - string state there is a fock space decomposition ( 8 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left | { closed \\ ; string \\ ; state } \\ right \\ rangle = \\ left | { open \\ ; string \\ ; state } \\ right \\ rangle \\ ; \\ otimes \\ ; \\ left | { open \\ ; string \\ ; state } \\ right \\ rangle . $ $ \\ end { document } in the low energy limit this implies that states in a gravity field theory obey a similar factorization , ( 9 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left | { gravity \\ ; theory \\ ; state } \\ right \\ rangle = \\ left | { gauge \\ ; theory \\ ; state } \\ right \\ rangle \\ ; \\ otimes \\ ; \\ left | { gauge \\ ; theory \\ ; state } \\ right \\ rangle . $ $ \\ end { document } for example , in four dimensions each of the two physical helicity states of the graviton are given by the direct product of two vector boson states of identical helicity . the cases where the vectors have opposite helicity correspond to the antisymmetric tensor and dilaton . similarly , a spin 3/2 gravitino state , for example , is a direct product of a spin 1 vector and spin 1/2 fermion . note that decompositions of this type are not especially profound for free field theory and amount to little more than decomposing higher spin states as direct products of lower spin ones . what is profound is that the factorization holds for the full non - linear theory of gravity . the fact that the klt relations hold for the extensive variety of compactified string models implies that they should also be generally true in field theories of gravity . for the cases of four - and five - particle scattering amplitudes , in the field theory limit the klt relations reduce to : ( 10 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ m_4 ^ { tree } ( 1,2,3,4 ) = - i { s _ { 12 } } a_4 ^ { tree } ( 1,2,3,4 ) \\ ; a_4 ^ { tree } ( 1,2,3,4 ) , $ $ \\ end { document } ( 11 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { m_5 ^ { tree } ( 1,2,3,4,5 ) = - i { s _ { 12 } } { s _ { 34 } } a_5 ^ { tree } ( 1,2,3,4,5 ) \\ ; a_5 ^ { tree } ( 2,1,4,3,5 ) \\ ;\\ ; } \\ \\ { \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; + i { s _ { 13 } } { s _ { 24 } } a_5 ^ { tree } ( 1,2,3,4,5 ) \\ ; a_5 ^ { tree } ( 3,1,4,2,5 ) \\ , , } \\ end { array } $ $ \\ end { document } where the mn s are tree - level amplitudes in a gravity theory , the an s are color - stripped tree - level amplitudes in a gauge theory , and sij ( ki + kj ) . in these equations the polarization and momentum labels are suppressed , but the labelj = 1 , ... , n is kept to distinguish the external legs . the coupling constants have been removed from the amplitudes , but are reinserted below in eqs . an explicit generalization to n - point field theory gravity amplitudes may be found in appendix a of ref . . the klt relations before the field theory limit is taken may , of course , be found in the original paper . the klt equations generically hold for any closed string states , using their fock space factorization into pairs of open string states . although not obvious , the gravity amplitudes ( 10 ) and ( 11 ) have all the required symmetry under interchanges of identical particles . ( this is easiest to demonstrate in string theory by making use of an sl ( 2 , z ) symmetry on the string world sheet . ) in the field theory limit the klt equations must hold in any dimension , because the gauge theory amplitudes appearing on the right - hand side have no explicit dependence on the space - time dimension ; the only dependence is implicit in the number of components of momenta or polarizations . moreover , if the equations hold in , say , ten dimensions , they must also hold in all lower dimensions since one can truncate the theory to a lower - dimensional subspace . ( 10 ) and ( 11 ) are exactly the scattering amplitudes that one obtains via standard gravity feynman rules . the gauge theory amplitudes on the right - hand side may be computed via standard feynman rules available in any modern textbook on quantum field theory . after computing the full gauge theory amplitude , the color - stripped partial amplitudes an appearing in the klt relations ( 10 ) and ( 11 ) , may then be obtained by expressing the full amplitudes in a color trace basis : ( 12 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { a } _ n ^ { tree } ( 1,2 , ... \\ ; n ) = { g ^ { ( n - 2 ) } } \\ sum \\ limits _ \\ sigma { tr \\ left ( { { t ^ { { a _ { \\ sigma ( 1 ) } } } } ... , \\ ; \\ sigma ( n ) ) , } $ $ \\ end { document } where the sum runs over the set of all permutations , but with cyclic rotations removed and g as the gauge theory coupling constant . the an partial amplitudes that appear in the klt relations are defined as the coefficients of each of the independent color traces . in this formula , the t are fundamental representation matrices for the yang - mills gauge group su ( nc ) , normalized so that tr ( tt ) - . note that the an are completely independent of the color and are the same for any value of nc . ( 12 ) is quite similar to the way full open string amplitudes are expressed in terms of the string partial amplitudes by dressing them with chan - paton color factors . instead , it is somewhat more convenient to use color - ordered feynman rules since they directly give the an color - stripped gauge theory amplitudes appearing in the klt equations . when obtaining the partial amplitudes from these feynman rules it is essential to order the external legs following the order appearing in the corresponding color trace . one may view the color - ordered gauge theory rules as a new set of feynman rules for gravity theories at tree - level , since the klt relations allow one to convert the obtained diagrams to tree - level gravity amplitudes as shown in fig . figure 6the color - ordered gauge theory feynman rules for obtaining tree - level scattering amplitudes for gravity coupled to matter , via the klt equations . the greek indices are space - time ones and the latin ones are group theory ones . the curly lines are vectors , dotted ones scalars , and the solid ones fermions . the color - ordered gauge theory feynman rules for obtaining tree - level scattering amplitudes for gravity coupled to matter , via the klt equations . the greek indices are space - time ones and the latin ones are group theory ones . the curly lines are vectors , dotted ones scalars , and the solid ones fermions . to obtain the full amplitudes from the klt relations in eqs . ( 10 ) , ( 11 ) and their n - point generalization , the couplings need to be reinserted . in particular , when all states couple gravitationally , the full gravity amplitudes including the gravitational coupling constant are : ( 13 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ n ^ { tree } ( 1 , \\ ; ... \\ ; n ) = { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) ^ { ( n - 2 ) } } m_n ^ { tree } ( 1 , \\ ; ... \\ ; n ) , $ $ \\ end { document } where = 32gn expresses the coupling in terms of newton s constant gn . in general , the precise combination of coupling constants depends on how many of the interactions are gauge or other interactions and how many are gravitational . for the case of four space - time dimensions , it is very convenient to use helicity representation for the physical states . with helicity amplitudes the scattering amplitudes in either gauge or gravity theories are , in general , remarkably compact , when compared with expressions where formal polarization vectors or tensors are used . for each helicity , the graviton polarization tensors satisfy a simple relation to gluon polarization vectors : ( 14 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ varepsilon _ { \\ mu \\ nu } ^ + = \\ varepsilon _ \\ mu ^ + \\ varepsilon _ \\ nu ^ + , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; \\ varepsilon _ { \\ mu \\ nu } ^ - = \\ varepsilon _ \\ mu ^ - \\ varepsilon _ \\ nu ^ - . $ $ \\ end { document } the are essentially ordinary circular polarization vectors associated with , for example , circularly polarized light . the graviton polarization tensors defined in this way automatically are traceless , = 0 , because the gluon helicity polarization vectors satisfy = 0 . they are also transverse , k = k = 0 , because the gluon polarization vectors satisfy k = 0 , where k is the four momentum of either the graviton or gluon . using a helicity representation , berends , giele , and kuijf ( bgk ) in quantum chromodynamics ( qcd ) an infinite set of helicity amplitudes known as the parke - taylor amplitudes were already known . these maximally helicity violating ( mhv ) amplitudes describe the tree - level scattering of n gluons when all gluons but two have the same helicity , treating all particles as outgoing . ( the tree amplitudes in which all or all but one of the helicities are identical vanish . ) bgk used the klt relations to directly obtain graviton amplitudes in pure einstein gravity , using the known qcd results as input . remarkably , they also were able to obtain a compact formula for n - graviton scattering with the special helicity configuration in which two legs are of opposite helicity from the remaining ones . as a particularly simple example , the color - stripped four - gluon tree amplitude with two minus helicities and two positive helicities in qcd is given by ( 15 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ a_4 ^ { tree } ( 1_g ^ - , 2_g ^ - , 3_g ^ + , 4_g ^ + ) = \\ tfrac { { { s _ { 12 } } } } { { { s _ { 23 } } } } , $ $ \\ end { document } ( 16 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ a_4 ^ { tree } ( 1_g ^ - , 2_g ^ - , 4_g ^ + , 3_g ^ + ) = \\ tfrac { { { s _ { 12 } } } } { { s24 } } , $ $ \\ end { document } where the g subscripts signify that the legs are gluons and the superscripts signify the helicities . with the conventions used here , ( this differs from another common choice which is to keep track of which particles are incoming and which are outgoing . ) in these amplitudes , for simplicity , overall phases have been removed . the gauge theory partial amplitude in eq . ( 15 ) may be computed using the color - ordered feynman diagrams depicted in fig . ( 16 ) are similar except that the labels for legs 3 and 4 are interchanged . although qcd contains fermion quarks , they do not contribute to tree amplitudes with only external gluon legs because of fermion number conservation ; for these amplitudes qcd is entirely equivalent to pure yang - mills theory . figure 7the three color - ordered feynman diagrams contributing to the qcd partial amplitude in eq . the three color - ordered feynman diagrams contributing to the qcd partial amplitude in eq . the corresponding four - graviton amplitude follows from the klt equation ( 10 ) . after including the coupling from eq . ( 13 ) , the four - graviton amplitude is : ( 17 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { tree } ( 1_h ^ - , 2_h ^ - , 3_h ^ + , 4_h ^ + ) = { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) ^ 2 } { s _ { 12 } } \\ ; \\ times \\ ; \\ frac { { { s _ { 12 } } } } { { { s _ { 23 } } } } \\ ; \\ times \\ ; \\ frac { { { s _ { 12 } } } } { { { s _ { 24 } } } } , $ $ \\ end { document } where the subscript h signifies that the particles are gravitons and , as with the gluon amplitudes , overall phases are removed . as for the case of gluons , this amplitude necessarily must be identical to the result for pure einstein gravity with no other fields present , because any other states , such as an anti - symmetric tensor , dilaton , or fermion , do not contribute to n - graviton tree amplitudes . the reason is similar to the reason why the quarks do not contribute to pure glue tree amplitudes in qcd . these other physical states contribute only when they appear as an external state , because they couple only in pairs to the graviton . indeed , the amplitude ( 17 ) is in complete agreement with the result for this helicity amplitude obtained by direct diagrammatic calculation using the pure gravity einstein - hilbert action as the starting point ( taking into account the different hilbert action as the starting point ( and conventions for helicity ) . a sampling of these , to leading order in the graviton coupling , is ( 18 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { { m_4 } ( 1_g ^ + , 2_g ^ + , 3_h ^ - , 4_h ^ - ) = 0 , \\ , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { { m_4 } ( 1_g ^ - , 2_g ^ + , 3_h ^ - , 4_h ^ + ) = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 2 } { { \\ left | { \\ frac { { s _ { 23 } ^ 5 } } { { { s _ { 13 } } s _ { 12 } ^ 2 } } } \\ right | } ^ { 1/2 } } , } \\ \\ { { m_5 } ( 1_g ^ + , 2 _ { g , } ^ + 3_g ^ + ,4 _ g ^ - , 5_h ^ - ) = { g ^ 2 } \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) { { \\ left | { \\ frac { { s _ { 45 } ^ 4 } } { { { s _ { 12 } } { s _ { 23 } } { s _ { 34 } } { s _ { 41 } } } } } \\ right | } ^ { 1/2 } } , } \\ \\ { { m_5 } ( 1_g ^ + , 2_g ^ + , 3_h ^ + , 4_h ^ - , 5_h ^ - ) = 0 \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ end { array } $ $ \\ end { document } for the coefficients of the color traces tr [ t ... t ] following the ordering of the gluon legs . these formulae have been generalized to infinite sequences of maximally helicity - violating tree amplitudes for gluon amplitudes dressed by external gravitons . another set was obtained using the klt relations to find the pattern for an arbitrary number of legs . in doing this , it is extremely helpful to make use of the analytic properties of amplitudes as the momenta of various external legs become soft ( i. e. ki 0 ) or collinear ( i. e. ki parallel to kj ) , as discussed in the next subsection . cases involving fermions have not been systematically studied , but at least for the case with a single fermion pair the klt equations can be directly applied using the feynman rules in fig . 6 , without any modifications . for example , in a supergravity theory , the scattering of a gravitino by a graviton is ( 19 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ mathcal { m } _ 4 ^ { tree } ( 1 _ { \\ tilde h } ^ - , 2_h ^ - , 3_h ^ + , 4 _ { \\ tilde h } ^ + ) = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 2 } { s _ { 12 } } { a_4 } ( 1_g ^ - , 2_g ^ - , 3_g ^ + , 4_g ^ + ) { a_4 } ( 1 _ { \\ tilde g } ^ - , 2_g ^ - , 4 _ { \\ tilde g } ^ + , 3_g ^ + ) } \\ \\ { = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 2 } { s _ { 12 } } \\ ; \\ times \\ ; \\ frac { { { s _ { 12 } } } } { { { s _ { 23 } } } } \\ ; \\ times \\ ; \\ sqrt { \\ frac { { { s _ { 12 } } } } { { { s _ { 24 } } } } , } } \\ end { array } $ $ \\ end { document } where the subscript \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ tilde h $ $ \\ end { document } signifies a spin 3/2 gravitino and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ tilde g $ $ \\ end { document } signifies a spin 1/2 gluino . as a more subtle example , the scattering of fundamental representation quarks by gluons via graviton exchange also has a klt factorization : ( 20 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ mathcal { m } _ 4 ^ { \\ operatorname { ex } } ( 1_q ^ { - { i_1 } } ,2 _ { \\ bar q } ^ { + { { \\ bar i } _ 2 } } ,3 _ g ^ { - { a_3 } } ,4 _ g ^ { + { a_4 } } ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 2 } { s _ { 12 } } { a_4 } ( 1_s ^ { { i_1 } } ,2 _ s ^ { { { \\ bar i } _ 2 } } ,3 _ q ^ { - { a_3 } } ,4 _ { \\ bar q } ^ { + { a_4 } } ) { a_4 } ( 1_q ^ - , 2 _ { \\ bar q } ^ + , 4 _ { \\ bar q } ^ + , 3_q ^ - ) } \\ \\ { = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 2 } \\ frac { { \\ sqrt { \\ left | { s _ { 13 } ^ 3 { s _ { 23 } } } \\ right | } } } { { { s _ { 12 } } } } { \\ delta _ { { i_1 } } } ^ { { { \\ bar i } _ 2 } } { \\ delta ^ { { a_3 } { a_4 } } } , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ end { array } $ $ \\ end { document } where q and q are distinct massless fermions . in this equation , the gluons are factorized into products of fermions . on the right - hand sidethe group theory indices ( i1 , 2 , a3 , a4 ) are interpreted as global flavor indices but on the left - hand side they should be interpreted as color indices of local gauge symmetry . as a check , in ref . , for both amplitudes ( 19 ) and ( 20 ) , ordinary gravity feynman rules were used to explicitly verify that the expressions for the amplitudes are correct . cases with multiple fermion pairs are more involved . in particular , for the klt factorization to work in general , auxiliary rules for assigning global charges in the color - ordered amplitudes appear to be necessary . when an underlying string theory does exist , such as for the case of maximal supergravity discussed in section 7 , then the klt equations necessarily must hold for all amplitudes in the field theory limit . the above examples , however , demonstrate that the klt factorization of amplitudes is not restricted only to the cases where an underlying string theory exists . the analytic properties of gravity amplitudes as momenta become either soft ( ki 0 ) or collinear ( kj parallel to kj ) are especially interesting because they supply a simple demonstration of the tight link between the two theories . moreover , these analytic properties are crucial for constructing and checking gravity amplitudes with an arbitrary number of external legs . the properties as gravitons become soft have been known for a long time but the collinear properties were first obtained using the known collinear properties of gauge theories together with the klt relations . helicity amplitudes in quantum chromodynamics have a well - known behavior as momenta of external legs become collinear or soft . for the collinear case , at tree - level in quantum chromodynamicswhen two nearest neighboring legs in the color - stripped amplitudes become collinear , e.g. , k1 zp , k2 ( 1 - z ) p , and p = k1 + k2 , the amplitude behaves as : ( 21 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ a_n ^ { tree } ( 1,2 , ... , n ) \\ ; \\ mathop \\ to \\ limits ^ { { k_1 } | | { k_2 } } \\ sum \\ limits _ { \\ lambda = \\ pm } { split _ { - \\ lambda } ^ { qcd } { \\ ; ^ { tree } } ( 1,2 ) a _ { n - 1 } ^ { tree } ( { p ^ \\ lambda } , 3 , ... , \\ ; n ) } . $ $ \\ end { document } the function split - qcd tree ( 1 , 2 ) is a splitting amplitude , and is the helicity of the intermediate state p. ( the other helicity labels are implicit . ) the contribution given in eq . ( 21 ) is singular for k1 parallel to k2 ; other terms in the amplitude are suppressed by a power of \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ sqrt { { s _ { 12 } } } $ $ \\ end { document } , which vanishes in the collinear limit , compared to the ones in eq . one such splitting amplitude is ( 22 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ split _ - ^ { qcd } { \\ ; ^ { tree } } ( { 1 ^ + } , { 2 ^ + } ) = \\ frac { 1 } { { \\ sqrt { z ( 1 - z ) } } } \\ frac { 1 } { { \\ left \\ langle { 12 } \\ right \\ rangle } } , $ $ \\ end { document } where ( 23 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ left \\ langle { jl } \\ right \\ rangle = \\ sqrt { { s _ { ij } } } { e ^ { i \\ phi jl } } , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; \\ left | { jl } \\ right | = - \\ sqrt { { s _ { ij } } } { e ^ { - i \\ phi jl } } , $ $ \\ end { document } are spinor inner products , and jl is a momentum - dependent phase that may be found in , for example , ref . . in general , it is convenient to express splitting amplitudes in terms of these spinor inner products . the + and labels refer to the helicity of the outgoing gluons . since the spinor inner products behave as \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ sqrt { { s _ { ij } } } $ $ \\ end { document } , the splitting amplitudes develop square - root singularities in the collinear limits . if the two collinear legs are not next to each other in the color ordering , then there is no singular contribution , e.g. no singularity develops in antree ( 1,2,3 , ... , n ) for k1 collinear to k3 . from the structure of the klt relations ( 21 ) must hold for gravity since gravity amplitudes can be obtained from gauge theory ones . the klt relations give a simple way to determine the gravity splitting amplitudes , split . the value of the splitting amplitude may be obtained by taking the collinear limit of two of the legs in , for example , the five - point amplitude . taking k1 parallel to k2 in the five - point relation ( 11 ) and using eq . ( 13 ) yields : ( 24 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 5 ^ { tree } ( 1,2,3,4,5 ) \\ ; \\ mathop \\ to \\ limits ^ { { k_1 } | | { k_2 } } \\ ; \\ frac { \\ kappa } { 2 } \\ sum \\ limits _ { \\ lambda = \\ pm } { split _ { - \\ lambda } ^ { gravity \\ ; tree } ( 1,2 ) \\ mathcal { m } _ 4 ^ { tree } ( { p ^ \\ lambda } , 3,4,5 ) , } $ $ \\ end { document } where ( 25 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ spli { t ^ { gravity \\ ; tree } } ( 1,2 ) \\ ; = \\ ; - { s _ { 12 } } \\ ; \\ times \\ ; spli { t ^ { qcd } } { \\ ; ^ { tree } } ( 1,2 ) \\ ; \\ times \\ ; spli { t ^ { qcd } } { \\ ; ^ { tree } } ( 2,1 ) . $ $ \\ end { document } more explicitly , using eq . ( 22 ) then gives : ( 26 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ split _ - ^ { gravity } { \\ ; ^ { tree } } ( { 1 ^ + } , { 2 ^ + } ) = \\ frac { { - 1 } } { { z ( 1 - z ) } } \\ frac { { } } { { \\ left \\ langle { 12 } \\ right \\ rangle } } . $ $ \\ end { document } using the klt relations at n - points , it is not difficult to verify that the splitting behavior is universal for an arbitrary number of external legs , i. e. : ( 27 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ n ^ { tree } ( 1,2 , ... , \\ ; n ) \\ ; \\ mathop \\ to \\ limits ^ { { k_1 } | | { k_2 } } \\ ; \\ frac { \\ kappa } { 2 } \\ sum \\ limits _ { \\ lambda = \\ pm } { split _ { - \\ lambda } ^ { gravity } { \\ ; ^ { tree } } ( 1,2 ) } \\ ; \\ mathcal { m } _ { n - 1 } ^ { tree } ( { p ^ \\ lambda } , 3 , ... , \\ ; n ) . $ $ \\ end { document } ( since the klt relations are not manifestly crossing - symmetric , it is simpler to check this formula for some legs being collinear rather than others ; at the end all possible combinations of legs must give the same results , though . ) the general structure holds for any particle content of the theory because of the general applicability of the klt relations . in contrast to the gauge theory splitting amplitude ( 22 ) , the gravity splitting amplitude ( 26 ) is not singular in the collinear limit . ( 25 ) has canceled the pole . however , a phase singularity remains from the form of the spinor inner products given in eq . ( 23 ) , which distinguishes terms with the splitting amplitude from any others . in eq . ( 23 ) , the phase factor 12 rotates by 2 as \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ vec k_1 } $ $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ vec k_2 } $ $ \\ end { document } rotate once around their sum \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ vec p } $ $ \\ end { document } as shown in fig . ( 26 ) then undergoes a 4 rotation accounting for the angular - momentum mismatch of 2 between the graviton p and the pair of gravitons 1 and 2 . in the gauge theory case , the terms proportional to the splitting amplitudes ( 21 ) dominate the collinear limit . in the gravitational formula ( 27 ) , there are other terms of the same magnitude as / 12 as s120 . however , these non - universal terms do not acquire any additional phase as the collinear vectors \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ vec k_1 } $ $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ vec k_2 } $ $ \\ end { document } are rotated around each other . the collinear limit of any gravity tree amplitude must contain the universal terms given in eq . ( 27 ) thereby putting a severe restriction on the analytic structure of the amplitudes . figure 8as two momenta become collinear a gravity amplitude develops a phase singularity that can be detected by rotating the two momenta around the axis formed by their sum . as twomomenta become collinear a gravity amplitude develops a phase singularity that can be detected by rotating the two momenta around the axis formed by their sum . even for the well - studied case of momenta becoming soft one may again use the klt relation to extract the behavior and to rewrite it in terms of the soft behavior of gauge theory amplitudes . gravity tree amplitudes have the well known behavior ( 28 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ n ^ { tree } ( 1,2 , ... , \\ ; { n ^ + } ) \\ ; \\ mathop \\ to \\ limits ^ { { k_n } \\ to 0 } \\ ; \\ frac { \\ kappa } { 2 } \\ ;{ \\ mathcal { s } ^ { gravity } } ( { n ^ + } ) \\ ; \\ times \\ ; \\ mathcal { m } _ { n - 1 } ^ { tree } ( 1,2 , ... , n - 1 ) $ $ \\ end { document } as the momentum of graviton n becomes soft . in eq . ( 28 ) the soft graviton is taken to carry positive helicity ; parity can be used to obtain the other helicity case . one can obtain the explicit form of the soft factors directly from the klt relations , but a more symmetric looking soft factor can be obtained by first expressing the three - graviton vertex in terms of a yang - mills three - vertex ( see eq . the result is a simple formula expressing the universal function describing soft gravitons in terms of the universal functions describing soft gluons : ( 29 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ mathcal { s } ^ { gravity } } ( { n ^ + } ) = \\ sum \\ limits _ { i = 1 } ^ { n - 1 } { { s _ { ni } } { \\ mathcal { s } ^ { qcd } } ( { q_l } , { n ^ + } , i ) \\ ; \\ times \\ ;{ \\ mathcal { s } ^ { qcd } } ( { q_r } , { n ^ + } , i ) } , $ $ \\ end { document } where ( 30 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { \\ mathcal { s } ^ { qcd } } ( a , { n ^ + } , b ) = \\ frac { { \\ left \\ langle { ab } \\ right \\ rangle } } { { \\ left \\ langle { an } \\ right \\ rangle \\ left \\ langle { nb } \\ right \\ rangle } } $ $ \\ end { document } is the eikonal factor for a positive helicity soft gluon in qcd labeled by n , and a and b are labels for legs neighboring the soft gluon . in eq . ( 29 ) the momenta ql and qr are arbitrary null reference momenta . although not manifest , the soft factor ( 29 ) is independent of the choices of these reference momenta . by choosing ql = k1 and qr = kn - 1 the form of the soft graviton factor for kn 0 used in , for example , refs . the important point is that in the form ( 29 ) , the graviton soft factor is expressed directly in terms of the qcd gluon soft factor . since the soft amplitudes for gravity are expressed in terms of gauge theory ones , the probability of emitting a soft gravitonone interesting feature of the gravitational soft and collinear functions is that , unlike the gauge theory case , they do not suffer any quantum corrections . this is due to the dimensionful nature of the gravity coupling , which causes any quantum corrections to be suppressed by powers of a vanishing kinematic invariant . the dimensions of the coupling constant must be absorbed by additional powers of the kinematic invariants appearing in the problem , which all vanish in the collinear or soft limits . this observation is helpful because it can be used to put severe constraints on the analytic structure of gravity amplitudes at any loop order . consider the einstein - hilbert and yang mills lagrangians , ( 31 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l _ { eh } } = \\ frac { 2 } { { { \\ kappa ^ 2 } } } \\ sqrt { - g } r , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; { l _ { ym } } = - \\ frac { 1 } { 4 } f _ { \\ mu \\ nu } ^ a { f ^ { a \\ mu \\ nu } } , $ $ \\ end { document } where r is the usual scalar curvature and fgva is the yang mills field strength . an inspection of these two lagrangians does not reveal any obvious factorization property that might explain the klt relations . indeed , one might be tempted to conclude that the klt equations could not possibly hold in pure einstein gravity . however , although somewhat obscure , the einstein - hilbert lagrangian can in fact be rearranged into a form that is compatible with the klt relations ( as argued in this section ) . of course , there should be such a rearrangement , given that in the low energy limit pure graviton tree amplitudes in string theory should match those of einstein gravity . all other string states either decouple or can not enter as intermediate states in pure graviton amplitudes because of conservation laws . indeed , explicit calculations using ordinary gravity feynman rules confirm this to be true . ( in loops , any state of the string that survives in the low energy limit will in fact contribute , but in this section only tree amplitudes are being considered . ) one of the key properties exhibited by the klt relations ( 10 ) and ( 11 ) is the separation of graviton space - time indices into left and right sets . this is a direct consequence of the factorization properties of closed strings into open strings . consider the graviton field , h. we define the index to be a leftindex and the v index to be a right one . in string theory , the leftspace - time indices would arise from the world - sheet left - mover oscillator and the right ones from the right - mover oscillators . of course , since h is a symmetric tensor it does not matter which index is assigned to the left or to the right . in the klt relations each of the two indices of a graviton , we similarly call one of the gauge theories the left one and the other the right one . since the indices from each gauge theory can never contract with the indices of the other gauge theory , it must be possible to separate all the indices appearing in a gravity amplitude into left and right classes such that the ones in the left class only contract with left ones and the ones in the right class only with right ones . this was first noted by siegel , who observed that it should be possible to construct a complete field theory formalism that naturally reflects the left - right string theory factorization of space - time indices . in a set of remarkable papers , he constructed exactly such a formalism . with appropriate gauge choices , indices separate exactly into right and left categories , which do not contract with each other . this does not provide a complete explanation of the klt relations , since one would still need to demonstrate that the gravity amplitudes can be expressed directly in terms of gauge theory ones . nevertheless , this formalism is clearly a sensible starting point for trying to derive the klt relations directly from einstein gravity . hopefully , this will be the subject of future studies , since it may lead to a deeper understanding of the relationship of gravity to gauge theory . a lagrangian with the desired properties could , for example , lead to more general relations between gravity and gauge theory classical solutions . herewe outline a more straightforward order - by - order rearrangement of the einstein - hilbert lagrangian , making it compatible with the klt relations . a useful side - benefit is that this provides a direct verification of the klt relations up to five points starting from the einstein - hilbert lagrangian in its usual form . this is a rather non - trivial direct verification of the klt relations , given the algebraic complexity of the gravity feynman rules . in conventional gauges , the difficulty of factorizing the einstein - hilbert lagrangian into left and right partsgauge , for example , the quadratic part of the lagrangian is ( 32 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l_2 } = - \\ frac { 1 } { 2 } { h _ { \\ mu \\ nu } } { \\ partial ^ 2 } { h ^ { \\ mu \\ nu } } + \\ frac { 1 } { 4 } { h _ \\ mu } ^ \\ mu { \\ partial ^ 2 } { h _ \\ nu } ^ \\ nu , $ $ \\ end { document } so that the propagator is the one given in eq . ( 2 ) . although the first term is acceptable since left and right indices do not contract into each other , the appearance of the trace h in eq . ( 32 ) is problematic since it contracts a left graviton index with a right one . ( the indices are raised and lowered using the flat space metric gh and its inverse . ) in order for the kinematic term ( 32 ) to be consistent with the klt equations , all terms which contract a leftscalar field that can be used to remove the graviton trace from the quadratic terms in the lagrangian . the appearance of the dilaton as an auxiliary field to help rearrange the lagrangian is motivated by string theory , which requires the presence of such a field . following the discussion of refs . , consider instead a lagrangian for gravity coupled to a scalar : ( 33 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l _ { eh } } = \\ frac { 2 } { { { \\ kappa ^ 2 } } } \\ sqrt { - g } r + \\ sqrt { - g } { \\ partial ^ \\ mu } \\ phi \\ ;{ \\ partial _ \\ mu } \\ phi . $ $ \\ end { document } since the auxiliary field is quadratic in the lagrangian , it does not appear in any tree diagrams involving only external gravitons . ( for theories containing dilatons one can allow the dilaton to be an external physical state . ) in de donder gauge , for example , taking g = + h , the quadratic part of the lagrangian including the dilaton is ( 34 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l_2 } = - \\ frac { 1 } { 2 } { h _ { \\ mu \\ nu } } { \\ partial ^ 2 } { h ^ { \\ mu \\ nu } } + \\ frac { 1 } { 4 } { h _ \\ mu } ^ \\ mu { \\ partial ^ 2 } { h _ \\ nu } ^ \\ nu - \\ phi \\ ;{ \\ partial ^ 2 } \\ phi . $ $ \\ end { document } the term involving h can be eliminated with the field redefinitions ( 35 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { h _ { \\ mu \\ nu } } \\ to { h _ { \\ mu \\ nu } } + { \\ eta _ { \\ mu \\ nu } } \\ sqrt { \\ frac { 2 } { { d - 2 } } } \\ ; \\ phi $ $ \\ end { document } and ( 36 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ phi \\ to \\ frac { 1 } { 2 } { h _ \\ mu } ^ \\ mu + \\ sqrt { \\ frac { { d - 2 } } { 2 } } \\ ; \\ phi , $ $ \\ end { document } yielding ( 37 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { l_2 } \\ to - \\ frac { 1 } { 2 } { h ^ \\ mu } _ \\ nu { \\ partial ^ 2 } { h _ \\ mu } ^ \\ nu + \\ phi \\ ;{ \\ partial ^ 2 } \\ phi . $ $ \\ end { document } one might be concerned that the field redefinition might alter gravity scattering amplitudes . however , because this field redefinition does not alter the trace - free part of the graviton field it can not change the scattering amplitudes of traceless gravitons . of course , the rearrangement of the quadratic terms is only the first step . in order to make the einstein - hilbert lagrangian consistent with the klt factorization , a set of field variables should exist where all space - time indices can be separated into left and right classes . to do so , all terms of the form ( 38 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { h _ \\ mu } ^ \\ mu , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; { h _ \\ mu } ^ \\ nu { h _ \\ nu } ^ \\ lambda { h _ \\ lambda } ^ \\ mu , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; ... , $ $ \\ end { document } need to be eliminated since they contract left indices with right ones . a field redefinition that accomplishes this is : ( 39 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { g _ { \\ mu \\ nu } } = e \\ sqrt { \\ tfrac { 2 } { { d - 2 } } } \\ kappa \\ phi \\ ; { e ^ { \\ kappa { h _ { \\ mu \\ nu } } } } \\ equiv e \\ sqrt { \\ tfrac { 2 } { { d - 2 } } } \\ kappa \\ phi \\ ; \\ left ( { { \\ eta _ { \\ mu \\ nu } } + \\ kappa { h _ { \\ mu \\ nu } } + \\ frac { { { \\ kappa ^ 2 } } } { 2 } { h _ \\ mu } ^ \\ rho { h _ { \\ rho \\ nu } } + ... } \\ right ) . $ $ \\ end { document } this field redefinition was explicitly checked in ref . through \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { o } ( { h ^ 6 } ) $ $ \\ end { document } , to eliminate all terms of the type in eq . ( 38 ) , before gauge fixing . however , currently there is no formal understanding of why this field variable choice eliminates terms that necessarily contract left and right indices . it turns out that one can do better by performing further field redefinitions and choosing a particular non - linear gauge . the explicit forms of these are a bit complicated and may be found in ref . . with a particular gauge choice it is possible to express the off - shell three - graviton vertex in terms of yang - mills three vertices : ( 40 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { i { g ^ { { \\ mu _ 1 } { \\ nu _ 1 } , { \\ mu _ 2 } { \\ nu _ 2 } , { \\ mu _ 3 } { \\ nu _ 3 } , } } ( { k_1 } , { k_2 } , { k_3 } ) = \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { - \\ frac { i } { 2 } \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) \\ left [ { v _ { gn } ^ { { \\ mu _ 1 } { \\ mu _ 2 } { \\ mu _ 3 } } ( { k_1 } , { k_2 } , { k_3 } ) \\ ; \\ times \\ ; v _ { gn } ^ { { \\ nu _ 1 } { \\ nu _ 2 } { \\ nu _ 3 } } ( { k_1 } , { k_2 } , { k_3 } ) } \\ right . } \\ \\ { \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; + \\ left . { v _ { gn } ^ { { \\ mu _ 2 } { \\ mu _ 1 } { \\ mu _ 3 } } ( { k_2 } , { k_1 } , { k_3 } ) \\ ; \\ times \\ ; v _ { gn } ^ { { \\ mu _ 2 } { \\ mu _ 1 } { \\ mu _ 3 } } ( { k_2 } , { k_1 } , { k_3 } ) } \\ right ] , } \\ end { array } $ $ \\ end { document } where ( 41 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ v _ { gn } ^ { \\ mu \\ nu \\ rho } ( { k_1 } , { k_2 } , { k_3 } ) = i \\ sqrt 2 ( k_1 ^ \\ rho { \\ eta ^ { \\ mu \\ nu } } + k_2 ^ \\ mu { \\ eta ^ { \\ nu \\ rho } } + k_3 ^ \\ nu { \\ eta ^ { \\ rho \\ mu } } ) , $ $ \\ end { document } is the color - ordered gervais - neveu gauge yang - mills three - vertex , from which the color factor has been stripped . this is not the only possible reorganization of the three - vertex that respects the klt factorization . for example , another gauge that has a three - vertex that factorizes into products of color - stripped yang - mills three - vertices is the background - field version of de donder gauge for gravity and feynman gauge for qcd . ( however , background field gauges are meant for loop effective actions and not for tree - level s - matrix elements . ) interestingly , these gauge choices have a close connection to string theory . the above ideas represent some initial steps in reorganizing the einstein - hilbert lagrangian so that it respects the klt relations . an important missing ingredient is a derivation of the klt equations starting from the einstein - hilbert lagrangian ( and also when matter fields are present ) . in this section , the above discussion is extended to quantum loops through use of d - dimensional unitarity . the klt relations provide gravity amplitudes only at tree - level ; d - dimensional unitarity then provides a means of obtaining quantum loop amplitudes . in perturbationtheory this is tantamount to quantizing the theory since the complete scattering matrix can , at least in principle , be systematically constructed this way . amusingly , this bypasses the usual formal apparatus associated with quantizing constrained systems . more generally , the unitarity method provides a way to systematically obtain the complete set of quantum loop corrections order - by - order in the perturbative expansion whenever the full analytic behavior of tree amplitudes as a function of d is known . it always works when the particles in the theory are all massless . the method is well tested in explicit calculations and has , for example , recently been applied to state - of - the - art perturbative qcd loop computations . in quantum field theory the s - matrix links initial and final states . a basic physical property is that the s matrix must be unitary : ss = 1 . in perturbationtheory the feynman diagrams describe a transition matrix t defined by s - 1 + it , so that the unitarity condition reads ( 42 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ 2 \\ operatorname { im } { t _ { if } } = \\ sum \\ limits_j { t _ { ij } ^ * { t _ { jf } } , } $ $ \\ end { document } where i and f are initial and final states , and the sum is over intermediate states j ( and includes an integral over intermediate on - mass - shell momenta ) . ( 42 ) in terms of coupling constants , g for gauge theory and for gravity , and collecting terms of the same order . for example , the imaginary ( or absorptive ) parts of one - loop four - point amplitudes , which is order in gravity , are given in terms of the product of two four - point tree amplitudes , each carrying a power of . this is then summed over all two - particle states that can appear and integrated over the intermediate phase space ( see fig . figure 9the two - particle cut at one loop in the channel carrying momentum k1 + k2 . the two - particle cut at one loop in the channel carrying momentum k1 + k2 . ( 42 ) in integer dimensions one would encounter a difficulty with fully reconstructing the loop scattering amplitudes . since eq . ( 42 ) gives only the imaginary part one then needs to reconstruct the real part . this is traditionally done via dispersion relations , which are based on the analytic properties of the s matrix . these ambiguities are related to the appearance of rational functions with vanishing imaginary parts r ( si ) , where the si are the kinematic variables for the amplitude . a convenient way to deal with this problem is to consider unitarity in the context of dimensional regularization . by considering the amplitudes as an analytic function of dimension , at least for a massless theory , these ambiguities are not present , and the only remaining ambiguities are the usual ones associated with renormalization in quantum field theorythe reason there can be no ambiguity relative to feynman diagrams follows from simple dimensional analysis for amplitudes in dimension d = 4 - 2 . with dimensional regularization , amplitudes for massless particles necessarily acquire a factor of ( si ) for each loop , from the measure \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ int { { d ^ d } l } $ $ \\ end { document } . for small , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { ( - { s_i } ) ^ { - \\ epsilon } } r ( { s_i } ) = r ( { s_i } ) - \\ epsilon \\ ln ( - { s_i } ) r ( { s_i } ) + \\ mathcal { o } ( { \\ epsilon ^ 2 } ) $ $ \\ end { document } , so every term has an imaginary part ( for some si 0 ) , though not necessarily in terms which survive as 0 . thus , the unitarity cuts evaluated to \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { o } ( { \\ epsilon } ) $ $ \\ end { document } provide sufficient information for the complete reconstruction of an amplitude . furthermore , by adjusting the specific rules for the analytic continuation of the tree amplitudes to d - dimensions one can obtain results in the different varieties of dimensional regularization , such as the conventional one , the t hooft - veltman scheme , dimensional reduction , and the four - dimensional helicity scheme . it is useful to view the unitarity - based technique as an alternate way of evaluating sets of ordinary feynman diagrams by collecting together gauge - invariant sets of terms containing residues of poles in the integrands corresponding to those of the propagators of the cut lines . this gives a region of loop - momentum integration where the cut loop momenta go on shell and the corresponding internal lines become intermediate states in a unitarity relation . from this point of view , even more restricted regions of loop momentum integration may be considered , where additional internal lines go on mass shell . this amounts to imposing cut conditions on additional internal lines . in constructing the full amplitude from the cuts it is convenient to use unrestricted integrations over loop momenta , instead of phase space integrals , because in this way one can obtain simultaneously both the real and imaginary parts . the generalized cuts then allow one to obtain multi - loop amplitudes directly from combinations of tree amplitudes . as a first example , the generalized cut for a one - loop four - point amplitude in the channel carrying momentum k1 + k2 , as shown in fig .9 , is given by ( 43 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ sum \\ limits _ { states } { { { \\ int { \\ frac { { { d ^ d } { l_1 } } } { { { { ( 4 \\ pi ) } ^ d } } } \\ frac { i } { { l_1 ^ 2 } } \\ left . { \\ mathcal { a } _ 4 ^ { tree } ( - { l_1 } ,1,2 , { l_2 } ) \\ frac { i } { { l_2 ^ 2 } } \\ mathcal { a } _ 4 ^ { tree } ( - { l_2 } ,3,4 , { l_1 } ) } \\ right | } } _ { 2 - cut } } , } $ $ \\ end { document } where l2 = l1 - k1 - k2 , and the sum runs over all physical states of the theory crossing the cut . in this generalizedcut , the on - shell conditions l12 = l22 = 0 are applied even though the loop momentum is unrestricted . in addition , any physical state conditions on the intermediate particles should also be included . the real and imaginary parts of the integral functions that do have cuts in this channel are reliably computed in this way . however , the use of the on - shell conditions inside the unrestricted loop momentum integrals does introduce an arbitrariness in functions that do not have cuts in this channel . a less trivial two - loop example of a generalized double two particle cut is illustrated in panel ( a ) of fig . the product of tree amplitudes appearing in this cut is ( 44 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ sum \\ limits _ { states } { \\ mathcal { a } _ 4 ^ { tree } ( 1,2 , - { l_2 } , - { l_1 } ) \\ ; \\ times \\ ; \\ mathcal { a } _ 4 ^ { tree } ( { l_1 } , { l_2 } , - { l_3 } , - { l_4 } ) } } \\ \\ { { { \\ left . { \\ times \\ ; \\ mathcal { a } _ 4 ^ { tree } ( { l_4 } , { l_3 } ,3,4 ) } \\ right | } _ { 2 \\ times 2 - cut } } , } \\ end { array } $ $ \\ end { document } where the loop integrals and cut propagators have been suppressed for convenience . in this expressionthe on - shell conditions li2 = 0 are imposed on the li , i = 1 , 2 , 3,4 appearing on the right - hand side . this double cut may seem a bit odd from the traditional viewpoint in which each cut can be interpreted as the imaginary part of the integral . it should instead be understood as a means to obtain part of the information on the structure of the integrand of the two - loop amplitude . namely , it contains the information on all integral functions where the cut propagators are not cancelled . this separates the amplitude into a product of three tree amplitudes , integrated over loop momenta . this separates the amplitude into a product of three tree amplitudes , integrated over loop momenta . complete amplitudes are found by combining the various cuts into a single function with the correct cuts in all channels . this method works for any theory where the particles can be taken to be massless and where the tree amplitudes are known as an analytic function of dimension . the restriction to massless amplitudes is irrelevant for the application of studying the ultra - violet divergences of gravity theories . in any case , ( for the case with masses present the extra technical complication has to do with the appearance of functions such as m which have no cuts in any channel . this method has been extensively applied to the case of one - and two - loop gauge theory amplitudes and has been carefully cross - checked with feynman diagram calculations . here , the method is used to obtain loop amplitudes directly from the gravity tree amplitudes given by the klt equations . in the next section an example of how the method works in practice for the case of gravitythe unitarity method provides a natural means for applying the klt formula to obtain loop amplitudes in quantum gravity , since the only required inputs are tree - level amplitudes valid for d - dimensions ; this is precisely what the klt relations provide . although einstein gravity is almost certainly not a fundamental theory , there is no difficulty in using it as an effective field theory , in order to calculate quantum loop corrections . the particular examples discussed in this section are completely finite and therefore do not depend on a cutoff or on unknown coefficients of higher curvature terms in the low energy effective action . they are therefore a definite low energy prediction of any fundamental theory of gravity whose low energy limit is einstein gravity . ( although they are definite predictions , there is , of course , no practical means to experimentally verify them . ) the issue of divergences is deferred to section 7 . as a simple example of how the unitarity method gives loop amplitudes , consider the one - loop amplitude with four identical helicity gravitons and a scalar in the loop . the product of tree amplitudes appearing in the s12 channel unitarity cut depicted in fig .9 is ( 45 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { tree } ( - l_1 ^ s,1_h ^ + , 2_h ^ + , l_3 ^ s ) \\ ; \\ times \\ ; \\ mathcal { m } _ 4 ^ { tree } ( - l_3 ^ s,3_h ^ + , 4_h ^ + , l_1 ^ s ) , $ $ \\ end { document } where the superscript s indicates that the cut lines are scalars . the h subscripts on legs 1 ... 4 indicate that these are gravitons , while the + superscripts indicate that they are of plus helicity . from the klt expressions ( 10 ) the gravity tree amplitudes appearing in the cuts may be replaced with products of gauge theory amplitudes . the required gauge theory tree amplitudes , with two external scalar legs and two gluons , may be obtained using color - ordered feynman diagrams and are ( 46 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { a } _ 4 ^ { tree } ( - l_1 ^ s,1_g ^ + , 2_g ^ + , l_3 ^ s ) = i \\ frac { { { \\ mu ^ 2 } } } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } , $ $ \\ end { document } ( 47 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { a } _ 4 ^ { tree } ( - l_1 ^ s,1_g ^ + , l_3 ^ s,2_g ^ + ) = - i { \\ mu ^ 2 } \\ left [ { \\ frac { 1 } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } + \\ frac { 1 } { { { { ( { l_1 } - { k_2 } ) } ^ 2 } } } } \\ right ] . $ $ \\ end { document } the external gluon momenta are four - dimensional , but the scalar momenta l1 and l3 are d - dimensional since they will form the loop momenta . in general , loop momenta will have a non - vanishing ( 2 ) - dimensional component \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ vec \\ mu $ $ \\ end { document } , with \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ vec \\ mu \\ cdot \\ vec \\ mu = { \\ mu ^ 2 } 0 $ $ \\ end { document } . the factors of appearing in the numerators of these tree amplitudes causes them to vanish as the scalar momenta are taken to be four - dimensional , though they are non - vanishing away from four dimensions . for simplicity , overall phases have been removed from the amplitudes . after inserting these gauge theory amplitudes in the klt relation ( 10 ) , one of the propagators cancels , leaving ( 48 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { tree } ( - l_1 ^ s,1_h ^ + , 2_h ^ + , l_3 ^ s ) = - i { \\ mu ^ 4 } \\ left [ { \\ frac { 1 } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } + \\ frac { 1 } { { { { ( { l_1 } - { k_2 } ) } ^ 2 } } } } \\ right ] . $ $ \\ end { document } for this cut , one then obtains a sum of box integrals that can be expressed as ( 49 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ int { \\ frac { { { d ^ d } { l_1 } } } { { { { ( 2 \\ pi ) } ^ d } } } { \\ mu ^ 8 } \\ frac { i } { { l_1 ^ 2 } } \\ left [ { \\ frac { i } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } + \\ frac { i } { { { { ( { l_1 } - { k_2 } ) } ^ 2 } } } } \\ right ] } \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { \\ times \\ ; \\ frac { i } { { { { ( { l_1 } - { k_1 } - { k_2 } ) } ^ 2 } } } \\ left [ { \\ frac { i } { { { { ( { l_1 } - { k_3 } ) } ^ 2 } } } + \\ frac { i } { { { { ( { l_1 } - { k_4 } ) } ^ 2 } } } } \\ right ] . } \\ end { array } $ $ \\ end { document } by symmetry , since the helicities of all the external gravitons are identical , the other two cuts also give the same combinations of box integrals , but with the legs permuted . the three cuts can then be combined into a single function that has the correct cuts in all channels yielding ( 50 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { m_4 ^ { 1 \\ ; loop } ( 1_h ^ + , 2_h ^ + , 3_h ^ + , 4_h ^ + ) = 2 \\ left ( { \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } [ { \\ mu ^ 8 } ] ( { s _ { 12 } } , { s _ { 23 } } ) + \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } [ { \\ mu ^ 8 } ] ( { s _ { 12 } } , { s _ { 13 } } ) } \\ right . } \\ \\ { \\ left . { + \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } [ { \\ mu ^ 8 } ] ( { s _ { 23 } } , { s _ { 13 } } ) } \\ right ) , } \\ end { array } $ $ \\ end { document } and where ( 51 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } [ \\ mathcal { p } ] ( { s _ { 12 } } , { s _ { 23 } } ) = \\ int { \\ frac { { { d ^ d } l } } { { { { ( 2 \\ pi ) } ^ d } } } \\ frac { \\ mathcal { p } } { { { l ^ 2 } { { ( l - { k_1 } ) } ^ 2 } { { ( l - { k_1 } - { k_2 } ) } ^ 2 } { { ( l + { k_4 } ) } ^ 2 } } } } $ $ \\ end { document } is the box integral depicted in fig . 11 with the external legs arranged in the order 1234 . in eq . ( 50 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { p } $ $ \\ end { document } is . the two other integrals that appear correspond to the two other distinct orderings of the four external legs . ( 50 ) is a combinatoric factor due to taking the scalars to be complex with two physical states . each internal line in the box corresponds to one of the four feynman propagators in eq . each internal line in the box corresponds to one of the four feynman propagators in eq . since the factor of is of \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { o } ( \\ epsilon ) $ $ \\ end { document } , the only non - vanishing contributions come where the e from the interferes with a divergence in the loop integral . these divergent contributions are relatively simple to obtain . after extracting this contribution from the integral , the final d = 4 result for a complex scalar loop , after reinserting the gravitational coupling , is ( 52 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { 1 \\ ; loop } ( 1_h ^ + , 2_h ^ + , 3_h ^ + , 4_h ^ + ) = \\ frac { 1 } { { { { ( 4 \\ pi ) } ^ 2 } } } { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) ^ 4 } \\ frac { { s _ { 12 } ^ 2 + s _ { 23 } ^ 2 + s _ { 13 } ^ 2 } } { { 120 } } , $ $ \\ end { document } in agreement with a calculation done by a different method relying directly on string theory . for any theory of gravity , with an arbitrary matter content one finds : ( 53 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { 1 \\ ; loop } ( 1_h ^ + , 2_h ^ + , 3_h ^ + , 4_h ^ + ) = \\ frac { { { n_s } } } { 2 } \\ frac { 1 } { { { { ( 4 \\ pi ) } ^ 2 } } } { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) ^ 4 } \\ frac { { s _ { 12 } ^ 2 + s _ { 23 } ^ 2 + s _ { 13 } ^ 2 } } { { 120 } } , $ $ \\ end { document } where ns is the number of physical bosonic states circulating in the loop minus the number of fermionic states . the simplest way to demonstratethis is by making use of supersymmetry ward identities , which provide a set of simple linear relations between the various contributions showing that they must be proportional to each other . surprisingly , the above four - point results can be extended to an arbitrary number of external legs . using the unitarity methods , the five - and six - point amplitudes with all identical helicitythen by demanding that the amplitudes have the properties described in section 3.4 for momenta becoming either soft or collinear , an ansatz for the one - loop maximally helicity - violating amplitudes for an arbitrary number of external legs has also been obtained . these amplitudes were constructed from a set of building blocks called half - soft - function , which have half of the proper behavior as gravitons become soft . the details of this construction and the explicit forms of the amplitudes may be found in refs . . the all - plus helicity amplitudes turn out to be very closely related to the infinite sequence of one - loop maximally helicity - violating amplitudes in n = 8 supergravity . the two sequences are related by a curious dimension shifting formula . in ref . , a known dimension shifting formula between identical helicity qcd and n = 4 super - yang - mills amplitudes was used to obtain the four - , five - , and six - point n = 8 amplitudes from the identical helicity gravity amplitudes using the klt relations in the unitarity cuts . armed with these explicit results , the soft and collinear properties were then used to obtain an ansatz valid for an arbitrary number of external legs . this provides a rather non - trivial illustration of how the klt relations can be used to identify properties of gravity amplitudes using known properties of gauge theory amplitudes . interestingly , the all - plus helicity amplitudes are also connected to self - dual gravity and self - dual yang mills , i. e. gravity and gauge theory restricted to self - dual configurations of the respective field strengths , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { r _ { \\ mu \\ nu \\ ; \\ rho \\ sigma } } = \\ tfrac { i } { 2 } \\ epsilon { _ { \\ mu \\ nu } } ^ { \\ alpha \\ beta } { r _ { \\ alpha \\ beta \\ rho \\ sigma } } $ $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ { f _ { \\ mu \\ nu } } = \\ tfrac { i } { 2 } \\ epsilon { _ { \\ mu \\ nu } } ^ { \\ alpha \\ beta } { r _ { \\ alpha \\ beta } } $ $ \\ end { document } , with 0123 = + 1 . this connection is simple to see at the linearized ( free field theory ) level since a superposition of plane waves of identical helicity satisfies the self - duality condition . the self - dual currents and amplitudes have been studied at tree and one - loop levels . in particular , chalmers and siegel have presented self - dual actions for gauge theory ( and gravity ) , which reproduce the all - plus helicity scattering amplitudes at both tree and one - loop levels . the ability to obtain exact expressions for gravity loop amplitudes demonstrates the utility of this approach for investigating quantum properties of gravity theories . the next section describes how this can be used to study high energy divergence properties in quantum gravity . in general , the larger the number of supersymmetries , the tamer the ultraviolet divergences because of the tendency for these to cancel between bosons and fermions in a supersymmetric theory . in four - dimensionsmaximal n = 8 supergravity may therefore be expected to be the least divergent of all possible supergravity theories . moreover , the maximally supersymmetric gauge theory , n = 4 super - yang - mills , is completely finite , leading one to suspect that the superb ultraviolet properties of n = 4 super - yang - mills would then feed into improved ultra - violet properties for n = 8 supergravity via its relation to gauge theory . this makes the ultraviolet properties of n = 8 supergravity the ideal case to investigate first via the perturbative relationship to gauge theory . the maximal n = 8 supergravity amplitudes can be obtained by applying the klt equations to express them in terms of maximally supersymmetric n = 4 gauge theory amplitudes . for n = 8 supergravity , each of the states of the multiplet factorizes into a tensor product of n = 4 super - yang - mills states , as illustrated in eq . applying the klt equation ( 10 ) to the product of tree amplitudes appearing in the s12 channel two - particle cuts yields : ( 54 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ sum \\ limits _ { \\ mathop { states } \\ limits ^ { n - 8 } } { m_4 ^ { tree } ( - { l_1 } ,1,2 , { l_3 } ) \\ ; \\ times \\ ; m_4 ^ { tree } ( - { l_3 } ,3,4 , { l_1 } ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } } \\ \\ { = - s _ { 12 } ^ 2 \\ sum \\ limits _ { \\ mathop { states } \\ limits ^ { n - 4 } } { a_4 ^ { tree } ( - { l_1 } ,1,2 , { l_3 } ) \\ ; \\ times \\ ; a_4 ^ { tree } ( - { l_3 } ,3,4 , { l_1 } ) } } \\ \\ { \\ ;\\ ;\\ ;\\ ; \\ times \\ ; \\ sum \\ limits _ { \\ mathop { states } \\ limits ^ { n - 4 } } { a_4 ^ { tree } ( - { l_3 } ,1,2 , - { l_1 } ) \\ ; \\ times \\ ; a_4 ^ { tree } ( - { l_1 } ,3,4 , - { l_3 } ) } } \\ end { array } $ $ \\ end { document } where the sum on the left - hand side runs over all 256 states in the n = 8 supergravity multiplet . on the right - hand sidethe two sums run over the 16 states ( ignoring color degrees of freedom ) of the n = 4 super - yang - mills multiplet : a gluon , four weyl fermions and six real scalars . the n = 4 super - yang - mills tree amplitudes turn out to have a particularly simple sewing formula , ( 55 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ sum \\ limits _ { \\ mathop { states } \\ limits ^ { n - 4 } } { a_4 ^ { tree } ( - { l_1 } ,1,2 , { l_3 } ) \\ ; \\ times \\ ; a_4 ^ { tree } ( - { l_3 } ,3,4 , { l_1 } ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } } \\ \\ { = - i { s _ { 12 } } { s _ { 23 } } a_4 ^ { tree } ( 1,2,3,4 ) \\ frac { 1 } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } \\ frac { 1 } { { { { ( { l_3 } - { k_3 } ) } ^ 2 } } } , } \\ end { array } $ $ \\ end { document } which holds in any dimension ( though some care is required to maintain the total number of physical states at their four - dimensional values so as to preserve the supersymmetric cancellations ) . the simplicity of this result is due to the high degree of supersymmetry . using the gauge theory result ( 55 ) , it is a simple matter to evaluate eq . this yields : ( 56 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ sum \\ limits _ { \\ mathop { states } \\ limits ^ { n - 8 } } { m_4 ^ { tree } ( - { l_1 } ,1,2 , { l_3 } ) \\ ; \\ times \\ ; m_4 ^ { tree } ( - { l_3 } ,3,4 , { l_1 } ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } } \\ \\ { = i { s _ { 12 } } { s _ { 23 } } { s _ { 13 } } m_4 ^ { tree } ( 1,2,3,4 ) \\ left [ { \\ frac { 1 } { { { { ( { l_1 } - { k_1 } ) } ^ 2 } } } + \\ frac { 1 } { { { { ( { l_1 } - { k_2 } ) } ^ 2 } } } } \\ right ] } \\ \\ { \\ times \\ left [ { \\ frac { 1 } { { { { ( { l_3 } - { k_3 } ) } ^ 2 } } } + \\ frac { 1 } { { { { ( { l_3 } - { k_4 } ) } ^ 2 } } } } \\ right ] . \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ end { array } $ $ \\ end { document } the sewing equations for the s23 and s13 kinematic channels are similar to that of the s12 channel . applying eq . ( 56 ) at one loop to each of the three kinematic channels yields the one - loop four graviton amplitude of n = 8 supergravity , ( 57 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ mathcal { m } _ 4 ^ { 1 \\ ; loop } ( 1,2,3,4 ) = - i { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 4 } { s _ { 12 } } { s _ { 23 } } { s _ { 13 } } \\ ; m_4 ^ { tree } ( 1,2,3,4 ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { \\ times \\ left ( { \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } ( { s _ { 12 , } } { s _ { 23 } } ) + \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } ( { s _ { 12 , } } { s _ { 13 } } ) + \\ mathcal { i } _ 4 ^ { 1 \\ ; loop } ( { s _ { 23 , } } { s _ { 13 } } ) } \\ right ) , } \\ end { array } $ $ \\ end { document } in agreement with previous results . the gravitational coupling has been reinserted into this expression . ( 51 ) , inserting \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { p } \\ ; = 1 $ $ \\ end { document } . this is a standard integral appearing in massless field theories ; the explicit value of this integral may be found in many articles , including refs . . this result actually holds for any of the states of n = 8 supergravity , not just external gravitons . it is also completely equivalent to the result one obtains with covariant feynman diagrams including fadeev - popov ghosts and using regularization by dimensional reduction . a generic one - loop four - point gravity amplitude can have up to eight powers of loop momenta in the numerator of the integrand ; the supersymmetry cancellations have reduced it to no powers . at two loops , the two - particle cuts are obtained easily by iterating the one - loop calculation , since eq . the three - particle cuts are more difficult to obtain , but again one can recycle the corresponding cuts used to obtain the two - loop n = 4 super - yang - mills amplitudes . it turns out that the three - particle cuts introduce no other functions than those already detected in the two - particle cuts . after all the cuts are combined into a single function with the correct cuts in all channels , the n = 8 supergravity two - loop amplitude is : ( 58 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ begin { array } { * { 20 } { c } } { \\ mathcal { m } _ 4 ^ { 2 \\ ; loop } ( 1,2,3,4 ) = { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 6 } { s _ { 12 } } { s _ { 23 } } { s _ { 13 } } \\ ; m_4 ^ { tree } ( 1,2,3,4 ) \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ \\ { \\ times \\ left ( { s _ { 12 } ^ 2 \\ mathcal { i } _ 4 ^ { 2 \\ ; loop , p } \\ left ( { { s _ { 12 } } , { s _ { 23 } } } \\ right ) + s _ { 12 } ^ 2 \\ mathcal { i } _ 4 ^ { 2 \\ ; loop , p } \\ left ( { { s _ { 12 } } , { s _ { 13 } } } \\ right ) } \\ right . } \\ \\ { \\ ;\\ ;\\ ;\\ ;\\ ;\\ ; + s _ { 12 } ^ 2 \\ mathcal { i } _ 4 ^ { 2loop , np } ( { s _ { 12 } } , { s _ { 23 } } ) + s _ { 12 } ^ 2 \\ mathcal { i } _ 4 ^ { 2 \\ ; loop , np } ( { s _ { 12 } } , { s _ { 13 } } ) } \\ \\ { \\ left . { + \\ ; cyclic } \\ right ) , \\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ;\\ ; } \\ end { array } $ $ \\ end { document } where + cyclic instructs one to add the two cyclic permutations of legs ( 2 , 3 , 4 ) . the scalar planar and non - planar loop momentum integrals , \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { i } _ 4 ^ { 2 \\ ; \\ text { loop } , \\ ;{ \\ text { p } } } ( { s _ { 12 } } , { s _ { 23 } } ) $ $ \\ end { document } and \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { i } _ 4 ^ { 2 \\ ; \\ text { loop } , \\ ;{ \\ text { np } } } ( { s _ { 12 } } , { s _ { 23 } } ) $ $ \\ end { document } , are depicted in fig . all powers of loop momentum have cancelled from the numerator of each integrand in much the same way as at one loop , leaving behind only the feynman propagator denominators . the explicit values of the two - loop scalar integrals in terms of polylogarithms may be found in refs . figure 12the planar and non - planar scalar integrals , appearing in the two - loop n = 8 amplitudes . the planar and non - planar scalar integrals , appearing in the two - loop n = 8 amplitudes . . the two - loop amplitude ( 58 ) has been used by green , kwon , and vanhove to provide an explicit demonstration of the non - trivial m - theory duality between d = 11 supergravity and type ii string theory . in this case , the finite parts of the supergravity amplitudes are important , particularly the way they depend on the radii of compactified dimensions . a remarkable feature of the two - particle cutting equation ( 56 ) is that it can be iterated to all loop orders because the tree amplitude ( times some scalar denominators ) reappears on the right - hand side . although this iteration is in sufficient to determine the complete multi - loop four - point amplitudes , it does provide a wealth of information . in particular , for planar integrals it leads to the simple insertion rule depicted in fig . 13 for obtaining the higher loop contributions from lower loop ones .4 , because it can be assembled entirely from two - particle cuts . according to the insertion rule , the contribution corresponding to fig .4 is given by loop integrals containing the propagators corresponding to all the internal lines multiplied by a numerator factor containing 8 powers of loop momentum . this is to be contrasted with the 24 powers of loop momentum in the numerator expected when there are no supersymmetric cancellations . this reduction in powers of loop momenta leads to improved divergence properties described in the next subsection . figure 13starting from an 1 - loop planar diagram representing an integral function , an extra line may be added to the inside using this rule . starting from an 1 - loop planar diagram representing an integral function , an extra line may be added to the inside using this rule . since the two - loop n = 8 supergravity amplitude ( 58 ) has been expressed in terms of scalar integrals , it is straightforward to extract the divergence properties . the scalar integrals diverge only for dimension d 7 ; hence the two - loop n = 8 amplitude is manifestly finite in d = 5 and 6 , contrary to earlier expectations based on superspace power counting . the discrepancy between the above explicit results and the earlier superspace power counting arguments may be understood in terms of an unaccounted higher - dimensional gauge symmetry . once this symmetry is accounted forthe cutting methods provide much more than just an indication of divergence ; one can extract the explicit numerical coefficients of the divergences . for example , near d = 7 the divergence of the amplitude ( 58 ) is ( 59 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ \\ mathcal { m } _ 4 ^ { two - loop , d = 7 - 2 \\ epsilon } \\ left | { _ { div . } = \\ frac { 1 } { { 2 { { ( 4 \\ pi ) } ^ 7 } } } \\ frac { \\ pi } { 3 } \\ left ( { s _ { 12 } ^ 2 + s _ { 23 } ^ 2 + s _ { 13 } ^ 2 } \\ right ) { { \\ left ( { \\ frac { \\ kappa } { 2 } } \\ right ) } ^ 6 } \\ times { s _ { 12 } } { s _ { 23 } } { s _ { 13 } } m_4 ^ { tree } , } \\ right . $ $ \\ end { document } which clearly diverges when the dimensional regularization parameter 0 . in all casesthe linearized divergences take the form of derivatives acting on a particular contraction of riemann tensors , which in four dimensions is equivalent to the square of the bel - robinson tensor . this operator appears in the first set of corrections to the n = 8 supergravity lagrangian , in the inverse string - tension expansion of the effective field theory for the type ii superstring . therefore , it has a completion into an n = 8 supersymmetric multiplet of operators , even at the non - linear level . it also appears in the m - theory one - loop and two - loop effective actions . interestingly , the manifest d - independence of the cutting algebra allows the calculation to be extended to d = 11 , even though there is no corresponding d = 11 super - yang - mills theory . the result ( 58 ) then explicitly demonstrates that n = 1 , d = 11 supergravity diverges . in dimensional regularizationthere are no one - loop divergences so the first potential divergence is at two loops . further work on the structure of the d = 11 two - loop divergences in dimensional regularization has been carried out in ref . . the explicit form of the linearized n = 1 , d = 11 counterterm expressed as derivatives acting on riemann tensors along with a more general discussion of supergravity divergences may be found in ref . .13 , and counting the powers of loop momenta in these contributions leads to the simple finiteness condition ( 60 ) \\ documentclass [ 12 pt ] { minimal } \\ usepackage { amsmath } \\ usepackage { wasysym } \\ usepackage { amsfonts } \\ usepackage { amssymb } \\ usepackage { amsbsy } \\ usepackage { mathrsfs } \\ usepackage { upgreek } \\ setlength { \\ oddsidemargin } { - 69 pt } \\ begin { document } $ $ l \\ frac { { 10 } } { { d - 2 } } $ $ \\ end { document } ( with l 1 ) , where l is the number of loops . this formula indicates that n = 8 supergravity is finite in some other cases where the previous superspace bounds suggest divergences , e.g. d = 4 , l = 3 : the first d = 4 counterterm detected via the two - particle cuts of four - point amplitudes occurs at five , not three loops . further evidence that the finiteness formula is correct stems from the maximally helicity violating contributions to m - particle cuts , in which the same supersymmetry cancellations occur as for the two - particle cuts . moreover , a recent improved superspace power count , taking into account a higher - dimensional gauge symmetry , is in agreement with the finiteness formula ( 60 ) . further work would be required to prove that other contributions do not alter the two - particle cut power counting . a related open question is whether one can prove that the five - loop d = 4 divergence encountered in the two - particle cuts does not somehow cancel against other contributions because of some additional symmetry . it would also be interesting to explicitly demonstrate the non - existence of divergences after including all contributions to the three - loop amplitude . in any case , the explicit calculations using cutting methods do establish that at two loops maximally supersymmetric supergravity does not diverge in d = 5 , contrary to earlier expectations from superspace power counting . this review described how the notion that gravity ( gauge theory ) ( gauge theory ) can be exploited to develop a better understanding of perturbative quantum gravity . the kawai - lewellen - tye ( klt ) string theory relations give this notion a precise meaning at the semi - classical or tree - level . quantum loop effects may then be obtained by using d - dimensional unitarity . in a sense , this provides an alternative method for quantizing gravity , at least in the context of perturbative expansions around flat space . with this method , gauge theory tree amplitudes are converted into gravity tree amplitudes which are then used to obtain gravity loop amplitudes . the ability to carry this out implies that gravity and gauge theory are much more closely related than one might have deduced by an inspection of the respective lagrangians . some concrete applications were also described , including the computation of the two - loop four - point amplitude in maximally supersymmetric supergravity . the result of this and related computations is that maximal supergravity is less divergent in the ultraviolet than had previously been deduced from superspace power counting arguments . for the case of d = 4another example for which the relation is useful is for understanding the behavior of gravitons as their momenta become either soft or collinear with the momenta of other gravitons . the klt relations provide a means for expressing the graviton soft and collinear functions directly in terms of the corresponding ones for gluons in quantum chromodynamics . using the soft and collinear properties of gravitons , infinite sequences of maximally helicity violating gravity amplitudes with a single quantum loopwere obtained by bootstrapping from the four - , five - , and six - point amplitudes obtained by direct calculation using the unitarity method together with the klt relations . interestingly , for the case of identical helicity , the sequences of amplitudes turn out to be the same as one gets from self - dual gravity . using the relationship of gravity to gauge theory one should be able to systematically re - examine the divergence structure of non - maximal theories . where the divergences of type i supergravity in d = 8 , 10 were shown to split into products of gauge theory factors . more generally , it should be possible to systematically re - examine finiteness conditions order - by - order in the loop expansion to more thoroughly understand the divergences and associated non - renormalizability of quantum gravity . an important outstanding problem is the lack of a direct derivation of the klt relations between gravity and gauge theory tree amplitudes starting from their respective lagrangians . as yet , there is only a partial understanding in terms of a left - right factorization of space - time indices , which is a necessary condition for the klt relations to hold . a more complete understanding may lead to a useful reformulation of gravity where properties of gauge theories can be used to systematically understand properties of gravity theories and vice versa . connected with this is the question of whether the heuristic notion that gravity is a product of gauge theories can be given meaning outside of perturbation theory . in summary , the perturbative relations between gravity and gauge theory provide a new tool for understanding non - trivial properties of quantum gravity . however , further work will be required to unravel fully the intriguing relationship between the two theories .\noutput:\n" }, { "from": "agent", "value": "in this review we describe a non - trivial relationship between perturbative gauge theory and gravity scattering amplitudes . at the semi - classical or tree - level , the scattering amplitudes of gravity theories in flat space can be expressed as a sum of products of well defined pieces of gauge theory amplitudes . these relationships were first discovered by kawai , lewellen , and tye in the context of string theory , but hold more generally . in particular , they hold for standard einstein gravity . a method based on d - dimensional unitarity can then be used to systematically construct all quantum loop corrections order - by - order in perturbation theory using as input the gravity tree amplitudes expressed in terms of gauge theory ones . more generally , the unitarity method provides a means for perturbatively quantizing massless gravity theories without the usual formal apparatus associated with the quantization of constrained systems . as one application , this method was used to demonstrate that maximally supersymmetric gravity is less divergent in the ultraviolet than previously thought ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: evidence - based health policy strongly depends on the quality of evidence that mostly driven from scientific productions . in these interactive complex cycles , ongoing monitoring provides the maximum level of quality and efficiency that contain planning , conducting , and different aspect of application of researches . designing and implementation of these preventive or controlling programs require to accurate information and scientific evidence provided through related papers and reports . with aim to monitoring and assessment of scientific trends , regardless of some limitations , scientometrics approaches provide reliable practical methods that measure , evaluate , and analyze scientific products of specific fields or units . in thisregard , using qualitative / quantitative and computational approaches , different indicators are increasingly employed to show the pattern of research outputs by researchers , universities , institutes , and countries . one of its main indices is the number of published articles or science production in specific domains of sciences . the number of published articles is a frequently used scientometric indicator of the scientific situation of those domains or units . citations of papers is another index that mostly uses as a proxy of quality and application of papers . the collaboration in research conducted and papers publication is considered as another citation indexes . considering the above , the aim of this study is scientometrics analysis of 15 - year health researchers productions and its contribution in total research production of iran . in these analyses , the contribution of health researchers in trends of published papers , citations , and collaborative researches during the past 15 - year period is presented by more details . the present study is a scientometrics analysis of more than one - decade contribution of health scientific papers in iranian scientific productions ( 20002014 ) . reviewingthe publication number , publication trends , citations , and collaborative institutions has been compared with total scientific productions of country . as it was the only source for multidisciplinary citation reports and regarding its most coverage in health and biomedicine disciplines , we systematically searched scopus database as the valid source of citation reports of knowledge products . we also introduce top institutions , journals , and collaborative research centers in the field of health sciences . using methods of reviews and considering emtree , based on defined aim of the study , for 15 years period of 20002014refining of all fields results is followed through limitation of source types to journals and subject areas to medicine , biochemistry , genetics and molecular biology , dentistry , health professions , and nursing as the main related fields that cover health research . search strategy has designed by research group and validated by external scientific group . the period of the study was limited to 20002014 , and there was no limitation for language [ table 1 ] . using pearson 's chi - square , p - trends were estimated by stata version 11 ( statacorp , college station , tx , usa ) . given data , during 20002014 , 237,056 scientific papers have been published in all fields of publication sciences . from them , 81,867 ( 34.53 % ) were assigned to health fields including medicine , biochemistry , genetics and molecular biology , dentistry , health professions , and nursing . pearson chi - square test confirmed significant time trends of published papers ( p = 0.000 ) . time trends of articles and their citations in total fields , iran had the most collaborative papers with the usa ( 9883 , 4.17 % ) , the uk ( 5719 , 2.41 % ) , and canada ( 5553 , 2.34 % ) . international contributions of in health papers had similar patterns . in this view , the first collaborative country in papers was the usa ( 3885 , 4.75 % ) . after that , the uk and canada with 2268 ( 2.77 % ) and 1580 ( 1.93 % ) papers , had second and third ranks , respectively . in overall , at national level , most of the papers were published in fields of medicine ( 24.17 % ) , engineering ( 19.09 % ) , and chemistry ( 16.79 % ) . in health domains , after that , the highest proportion of publications belonged to biochemistry , genetics and molecular biology ( 14.54 % ) , and pharmacology , toxicology , and pharmaceutics sciences ( 8.51 % ) . figure 2 compares the distribution of subject area of health domains and total fields publications . distribution of subject area of ( a ) total fields and ( b ) health domains publications considering the role of research centers , universities , or other scientific institutes in the publication of papers , azad university , tehran university of medical sciences , and university of tehran with 32,579 ( 13.74 % ) , 22,357 ( 9.43 % ) , and 21,792 ( 9.19 % ) papers had the most contribution in national scientific papers , respectively . in medical and health - related fields , the third rank belonged to shahid beheshti university of medical sciences , with 7.28 % counterpart [ figure 3 ] . contribution of national universalities / scientific institutes in publication of ( a ) total and ( b ) health related papers , 20002014 regarding the sources of publication , life science journal , advances in environmental biology , and australian journal of basic and applied sciences with 0.85 % , 0.82 % , and 0.70 % of national publication contribution were the top three sources of iranian publication , respectively . for health domains publications , life science journal ( 2.1 % ) , australian journal of basic and applied sciences ( 1.85 % ) , and world applied sciences journal ( 3.6 % ) had first three ranks . from iranian journal , archives of iranian medicine ( 0.57 % ) , scientia iranica ( 0.53 % ) , and journal of research in medical sciences ( 0.52 % ) had the most contribution in total publication . archives of iranian medicine , journal of research in medical sciences , and acta medica iranica with 1.54 % , 1.38 % , and 1.32 % of national publication contribution were the top three sources of health - related publication , respectively . during this period , the most prevalent type of total publication was original articles which consist of 93.1 % of all knowledge products . after that , review articles ( 2.2 % ) and letters ( 1.4 % ) set on next levels . these distributions with similar patternfigure 4 shows the distribution of article type . the national distribution of ( a ) total and ( b ) health - related article typegiven data , during 20002014 , 237,056 scientific papers have been published in all fields of publication sciences . from them , 81,867 ( 34.53 % ) were assigned to health fields including medicine , biochemistry , genetics and molecular biology , dentistry , health professions , and nursing . pearson chi - square test confirmed significant time trends of published papers ( p = 0.000 ) . in total fields , iran had the most collaborative papers with the usa ( 9883 , 4.17 % ) , the uk ( 5719 , 2.41 % ) , and canada ( 5553 , 2.34 % ) . international contributions of in health papers had similar patterns . in this view , the first collaborative country in papers was the usa ( 3885 , 4.75 % ) . after that , the uk and canada with 2268 ( 2.77 % ) and 1580 ( 1.93 % ) papers , had second and third ranks , respectively . in overall , at national level , most of the papers were published in fields of medicine ( 24.17 % ) , engineering ( 19.09 % ) , and chemistry ( 16.79 % ) . in health domains , after that , the highest proportion of publications belonged to biochemistry , genetics and molecular biology ( 14.54 % ) , and pharmacology , toxicology , and pharmaceutics sciences ( 8.51 % ) . figure 2 compares the distribution of subject area of health domains and total fields publications . distribution of subject area of ( a ) total fields and ( b ) health domains publicationsconsidering the role of research centers , universities , or other scientific institutes in the publication of papers , azad university , tehran university of medical sciences , and university of tehran with 32,579 ( 13.74 % ) , 22,357 ( 9.43 % ) , and 21,792 ( 9.19 % ) papers had the most contribution in national scientific papers , respectively . in medical and health - related fields , the third rank belonged to shahid beheshti university of medical sciences , with 7.28 % counterpart [ figure 3 ] . contribution of national universalities / scientific institutes in publication of ( a ) total and ( b ) health related papers , 20002014 regarding the sources of publication , life science journal , advances in environmental biology , and australian journal of basic and applied sciences with 0.85 % , 0.82 % , and 0.70 % of national publication contribution were the top three sources of iranian publication , respectively . for health domains publications , life science journal ( 2.1 % ) , australian journal of basic and applied sciences ( 1.85 % ) , and world applied sciences journal ( 3.6 % ) had first three ranks . from iranian journal , archives of iranian medicine ( 0.57 % ) , scientia iranica ( 0.53 % ) , and journal of research in medical sciences ( 0.52 % ) had the most contribution in total publication . archives of iranian medicine , journal of research in medical sciences , and acta medica iranica with 1.54 % , 1.38 % , and 1.32 % of national publication contribution were the top three sources of health - related publication , respectively . during this period , the most prevalent type of total publication was original articles which consist of 93.1 % of all knowledge products . after that , review articles ( 2.2 % ) and letters ( 1.4 % ) set on next levels . these distributions with similar patternfigure 4 shows the distribution of article type . the national distribution of ( a ) total and ( b ) health - related article typethe results of the present study verify the position of iran 's health researches between total scientific productions . this is vital for countries to assess and monitor the trends and possible challenges of research productions based on their research visions . in iran , at least one - third share of science products assign to health domains and there is a significant correlation between publication and their citations . in thisthe trends and variations of science and technology publications mostly supervised through scientometrics indicators provide the best practical evidence . such estimations , through detailed analyses of situations and possible scenarios , provide the possibility of the evidence - based management of knowledge production at levels of research units or even in specific domains of science . in iran , goals of health researchers are followed exactly based on national convention policies . aim to that , the comprehensive scientific map of iran overwhelms the goals , policies , strategies , and requisites . this document emphasized on health research as one of the core components of health society and improvement of quality of life , and iran is pictured as the highest developed country in science / technology by 2025 . in line with the present results , other evidencereveal that , during the recent years , the number of published articles has significantly increased in the fields of basic and applied sciences . iran has one of the fastest growth rates in scientific productions in the world , with a considerable growth in health publications . these observed rapid increasing trends in research outputs can be attributed to the national commitment and attention of policy - makers , in highest level of leadership that has caused a strong support in equipment of facilities and resources . moreover , the recent improvement of the subject of science editing , mostly managed by expert editors , should be considered as one of the most facilitators of the progressive quality of publications such as indexing , online management of journals , and other related processes . health research essentially involves different wide multidisciplinary collaborations and sometimes across multiple organizations potentially , provide more facilities for increasing the citations and applications of papers . our analyses revealed that citation as one of the representative indexes for paper 's application and quality , regardless present planned ascending pattern , in adjusted forms of parametric indexes such as citation per paper , needs to be more attention . leading organization with higher rate of collaborative papers , resource allocation , and high - cited productions should be recognized as rich capital of sharing experiences . it is important policy consideration that the increasing trends of related multidisciplinary research centers as well as faculties and consequently the increase of health research specialists , students , projects , and dissertations are positive potential factors which influence the rise in the number and citations of papers in these fields . considering the design and conduction approaches , the present study benefited from many strength points . first , to clarify the exact pattern of knowledge production in health researches , we focused on specific domain . second , during a systematic search of data , we benefited from the most comprehensive co - national international database with the most coverage . fourth , we explain the situation of health researches as one of the most effective knowledge productive countries in total contribution in details . moreover , a large amount of data , especially in evaluation of citation trends , led to some time - consuming processes . to the best of our knowledge , this is the first scientometrics analysis 15 years of contribution of health knowledge productions in total scientific product of country that provide practical information for better research planning in related multidisciplinary fields . despite the ascending trends in health research outputs , more efforts required for the promotion of quality and better application of them . these analyses also could be useful for better planning and management of planning and conducting studies in these fields .\noutput:\n" }, { "from": "agent", "value": "background : researchers , practitioners , and policymakers call for updated valid evidence to monitor , prevent , and control of alarming trends of health problems . to respond to these needs , health researches provide the vast multidisciplinary scientific fields . we quantify the national trends of health research outputs and its contribution in total science products.methods : we systematically searched scopus database with the most coverage in health and biomedicine discipline as the only sources for multidisciplinary citation reports , for all total and health - related publications , from 2000 to 2014 . these scientometrics analyses covered the trends of main index of scientific products , citations , and collaborative papers . we also provided information on top institutions , journals , and collaborative research centers in the fields of health researches.results : in iran , over a 15 - year period , 237,056 scientific papers have been published , of which 81,867 ( 34.53 % ) were assigned to health - related fields . pearson 's chi - square test showed significant time trends between published papers and their citations . tehran university of medical sciences was responsible for 21.87 % of knowledge productions share . the second and the third ranks with 11.15 % and 7.28 % belonged to azad university and shahid beheshti university of medical sciences , respectively . in total fields , iran had the most collaborative papers with the usa ( 4.17 % ) , the uk ( 2.41 % ) , and canada ( 0.02 % ) . in health - related papers , similar patterns of collaboration followed by 4.75 % , 2.77 % , and 1.93 % of papers.conclusions : despite the ascending trends in health research outputs , more efforts required for the promotion of collaborative outputs that cause synergy of resources and the use of practical results . these analyses also could be useful for better planning and management of planning and conducting studies in these fields ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: in recent years , the quality of life has been considered an important index in medical research for evaluating the individual health status and for decision making and judgment about the general health of the society , as well as finding the main problems in different dimensions of life ( 1 ) . quality of life possesses different dimensions such as physical health , mental health , economic conditions , personal beliefs , and interaction with the environment ( 1 , 2 ) . also , it is regarded very important , as it includes several dimensions of the individual such as physiological aspects , performance , and the existence ( 3 ) . the quality of life is so important that the current century is called the century of improving life quality ( not only surviving ) and health status ( 4 , 5 ) . life quality confines not only to the health status aspects , but also many other factors ; however , health status is the core and the prerequisite of a good quality of life ( 6 , 7 ) . some scholars believe that life quality is the individual s evaluation of his or her health status and satisfaction gained from this understanding ( 8 ) . the world health organization has defined quality of life as the understanding that people have of their life situation in their cultural context and value systems which is related to their goals , expectation , and criteria in their lives ( 9 ) . therefore , quality of life can be defined as the physical , mental , and social welfare ( such as happiness , satisfaction , pride , health , economic status , educational opportunities , and so on ) which is understood by an individual or group ( 7 , 9 ) . health - related quality of life ( hrqol ) is a patient s perception of how his or her health status affects physical , psychological and social functioning , and well - being ( 10 ) . addiction , substance dependence and its illicit trade are nowadays one of the major concerns and health threatening factors in the world ( 11 , 12 ) . risk factors of narcotic drug abuse include family conflicts , education problems , and simultaneous occurrence of mental disorders such as depression and mood changes , drug abuse by parents and peers , and early onset of cigarette smoking . the more risk factors a person has , the higher would be the probability of drug abuse for that person ( 13 ) . in patients , life quality refers to a good situation which reflects the physical , mental and social status of the person . negative consequences of the mental status ( depression , anxiety , and collapse of family relationship ) , and physical status ( bodily pain and inertia ) of addiction are associated with drug abuse . these consequences result in the reduction of life quality and satisfaction in substance dependent people ( 14 - 16 ) . according to who report in 2008 , 200 million people in the world were opioid dependent and iran is also exposed to this social problem because of its geographical position ( 17 , 18 ) . drug dependence is more common among men and even some studies report that the prevalence of addiction among men is 15 times more than that among women in iran . the highest frequency of addiction is also in 20 - 35 years age group ( 17 ) . in recent years , a lot of attention has been paid to the health status and life quality , especially of the addicts ( 19 , 20 ) . the results of various studies indicate that the quality of life of addicts is lower than that of normal people ( 12 , 14 - 16 , 21 , 22 ) . some studies have also shown that methadone and buprenorphine maintenance treatments have had positive effects on the life quality of the addicts ( 23 - 27 ) . therefore , the current study aimed to determine the life quality of the referents to the addiction cessation centers in shahroud in the northeast of iran and its affecting factors . in this cross - sectional study , out of 26 methadone maintenance treatment centers in shahroud , 18 centers were randomly selected in 2013 and all patients in these centers were included in the study through census method . the data collection instruments included a 10 - item general questionnaire and sf - 36 questionnaire which had already been validated by montazeri and colleagues ( 28 ) . their study showed that the iranian version of sf - 36 is a reliable and valid measure of health - related quality of life among the general population . the cronbach 's alpha coefficient of all 8 scales of sf - 36 , range from 0.77 to 0.90 . factor analysis identified two principle components that jointly accounted for 65.9 % of the variance ( 28 ) . quality of life questionnaire ( sf - 36 ) is a general questionnaire which is used for assessing the health - related quality of life of people and addicts . these 2 scales comprise 8 subscales of physical functioning , role limitations due to physical health , bodily pain , general health , vitality , social functioning , role limitations due to emotional problems , and mental health . the questionnaire was administered to the participants and after the purpose of the study was explained to them , they completed the questionnaire . in casethe participant was illiterate or low - literate , the questionnaire was completed by a trained interviewer . the data were analyzed by chi - square and one - way anova to test the relationships between life quality and demographic features . the relationships between influencing factors and life quality were tested through linear regression in structural equation modeling ( sem ) . moreover , socioeconomic status of the participants was estimated based on variables such as income , residence , education , and occupation using sem . the confidence interval in the study was 95 % and the significance level was considered 0.05 . about 64.7 % of the participants were city - dwellers . around 18.2 % of the participants were illiterate and 9.3 % had university degrees . opium was the major substance ( 35.3 % ) used by the participants before they referred to methadone maintenance treatment ( mmt ) centers . most of the referents before referring to the centers used smoking method ( 41.8 % ) and eating method ( 31.2 % ) of the opium . about 18 % used both smoking and eating methods and 10.9 % used injection simultaneously with other methods . most of the participants after referring to the treatment centers used methadone ( 86.3 % ) , followed by opium syrup ( 12.6 % ) and buprenorphine ( 0.9 % ) . the mean sd period of drug abuse was 135.2104.5 months and the median period of drug abuse was 120 months and the interquartile range was 60 - 180 . the shortest period of drug abuse was 3 months and the longest was 720 months . the mean sd period of receiving methadone maintenance treatment was 14.816.1 months . the mean sd score of quality of life among the participants was 67.817.2 . the mean sd score of quality of life in the physical health domain was 68.619.4 and in mental health domain 64.818.4 . the highest mean sd score of quality of life belonged to physical functioning 76.926.7 and the lowest mean sd belonged to general health as 60.517.5 followed by vitality 6218.1 ( table 1 ) . comparison of the scores of life quality of the two genders showed a significant difference in all dimensions ( p 0.05 ) so that the scores of men in all subscales were higher . table 2 shows the mean scores of quality of life , physical health , and mental health based on the variables under study . data are presented as mean sd . the comparison of quality of life mean scores of employed and unemployed people in different subscales shows that the mean scores of vitality , physical health , mental health , social functioning , bodily pains , general health , total quality of life of employed participants were higher than those of the unemployed ones ( p 0.05 ) . moreover , the results showed that education has a significant influence on the scores of physical health , life quality , bodily pain , and general health subscales . the post hoc test of tukey showed that participants with university degrees had higher levels of life quality . a significant relationship was also observed between marital status and all dimensions of quality of life ( p 0.05 ) . the post hoc tukey test showed that married participants had a better life quality in all dimensions . one - way anova also showed a significant relationship between income and all subscales of life quality ( p 0.05 ) . a significant relationship was also observed between the housing status and all subscales of life quality except physical functioning ( p = 0.18 ) . the mean score of role limitation due to physical health and role limitation due to emotional functioning were observed to be 0.65 and 0.099 , respectively . the multivariate analysis of the relationships of socioeconomic status , age , gender , duration of drug abuse with quality of life showed that in the final model , significant relationships exist between quality of life and gender and socioeconomic status . the results indicated that addicted women had a lower quality of life than men and people with higher socioeconomic status have higher quality of life ( b = 0.18 ) ( table 3 ) . in this study , 94.5 % of the participants were men , which is consistent with the higher number of men in other studies ( 17 , 18 ) . perhaps one of the reasons for the higher number of men is the higher prevalence of addiction among men , as well as the fewer referring of women to self - introduction centers . in our study , a significant relationship was observed between quality of life and occupation so that employed participants showed higher levels of life quality which is in line with the findings of hojjati and colleagues ( 29 ) . in a cross - sectional study , 3005 addicted person were reviewed to assess the demographic characteristic , prototype of drug consumption , and its relation with some personal and social variation in gorgan ( northeast , iran ) ; 61.7 % of the subjects were either unemployed or without any real job ( 18 ) . unemployment and the financial problems which result from the addicts lack of role in the family and society reduce the quality of life in the addicts . the result of our study showed a significant relationship between education and quality of life which is consistent with the findings of timareh and colleagues on diabetes patients ( 30 ) . perhaps lower levels of education and fewer learning opportunities and facilities predispose people more toward substance abuse and as a result higher prevalence of addiction among them . a significant relationship was also observed between gender and quality of life which is consistent with the results of a study by gonzales et al . . the higher level of quality of life for men in the present study is also in accord with the findings of hojjati and colleagues ( 29 ) . the quality of life score in the addicts who referred to methadone maintenance treatment centers was more than 50 % which is in line with the study by hojjati and colleagues ( 29 ) . some studies indicate a lower level of quality of life for addicts in comparison to that of normal people ( 12 , 15 , 16 , 20 - 22 , 29 ) and some other studies showed the positive effect of methadone and buprenorphine maintenance treatment on the improvement of health related quality of life of addicts after they refer to treatment centers ( 14 , 19 , 23 - 26 ) . in a descriptive study which has been done in a cohort and longitudinal manner during 3 months ( from the beginning and 3 months after entrance ) the result of this study showed that detoxification has been effective in improving their quality of life ( 31 ) . ( 32 ) compared the quality of life and mental health between addicts and non - addicts . they showed that addicts live in the worst condition and need strong support and their quality of life was lower than of non addicts . the present results indicate that people who are under treatment in these centers have higher scores , which is in line with another study done in shahroud on the quality of life of non addicts ( 33 ) . perhaps one reason for the lack of difference between the quality of life of addicts and non - addicts is the effect of maintenance treatment . karow et al , in a longitudinal investigation of health - related quality of life in patients with severe opioid dependence , showed that health - related quality of life ( hrqol ) is associated with a successful treatment in opioid addiction ( 1 ) . about 64.7 % of participants were city - dwellers and the rest were villagers . a significant relationship was observed between quality of life and place of residence so that those living in village showed a lower score in all aspect of life quality . one limitation of this study was the dearth of relevant studies which could help discuss and compare our findings . moreover due to cultural issues , women do not tend to refer to treatment centers , so fewer numbers of women were studied . also , we recommend evaluation of the participants before and after maintenance treatments , so we could have a better assessment of addicts qol . although in most studies , the quality of life of drug dependent people was reported to be low , participants in this study showed a higher level of life quality and since all participants were receiving methadone or buprenorphine treatment , it seems that mmt centers could improve the quality of life of the addicts . therefore , expanding such centers can play a significant role in improving the quality of life of the addicts . the results of the study also suggest that more service should be provided to people with lower socioeconomic status . moreover , establishing treatment centers for women can encourage more voluntary reference to these centers by women and accordingly would lead to the improvement of their quality of life .\noutput:\n" }, { "from": "agent", "value": "background : measurement of life quality as an index of health status has a widespread application in health care domain.objectives : the current study aimed to determine the quality of life of referents to addiction cessation centers of iran.patients and methods : in this cross - sectional study , 988 addicts who had referred to addiction cessation centers in shahroud were studied through sf - 36 questionnaire . the data were analyzed using linear regression in structural equation modeling and stata 12 statistical software.results : the mean sd age of the participants was 41.2 11.8 years . most of the referents used smoking followed by eating method of opium abuse . the mean sd score of life quality was 67.8 17.2 , the mean sd score of life quality in physical health dimension was 76.9 26.7 , and the mean sd score in mental health dimension was 64.5 18.4 . univariate analysis showed a significant relationship between life quality and gender , place of residence , education , occupation , marital status , and income ( p 0.05 ) . however , in multivariate analysis a significant relationship was observed only between gender , socioeconomic status , and quality of life score.conclusions : although most studies have reported low and weak quality of life in addicts , the findings of this study shows that the life quality score of addicts is rather good . it seems that the maintenance treatment that addicts receive in addiction cessation centers has been effective in improving the quality of life of the patients . hence , expanding methadone treatment centers can play a leading role in the improvement of life quality in addicts ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: maltreatment encompasses a spectrum of abusive actions ( sexual , physical , or emotional abuse ) or lack of actions ( physical or emotional neglect ) by the parent or other caregivers . a psychiatric disorder associated with early life abuse and neglect is reactive attachment disorder ( rad ) , where the child displays wary , watchful , and emotionally withdrawn behaviours , according to the 5th edition of the diagnostic and statistical manual of mental disorders ( dsm - 5 ) . because of emotional dampening , rad closely resembles internalising disorders with depressive and anxiety symptoms . in populations of maltreated children in foster care , 19.440.0 % had signs of rad based on the dsm - iv criteria , in which rad ( the inhibited type of rad ) and disinhibited social engagement disorder ( dsed ; the disinhibited type of rad ) were not completely independent . even in a general population , the prevalence of rad based on the dsm - iv criteria has been reported in 1.4 % of children and children with rad are more likely to have multiple comorbidities with other disorders , such as attention deficit hyperactivity disorder ( adhd ; 52 % ) , post - traumatic stress disorder ( ptsd ; 19 % ) , and autism spectrum disorder ( asd ; 14 % ) . despite its high prevalence and clinical importance , there have been very few investigations into the possible neurobiological consequences of rad . of the childhood psychiatric disorders , rad , which is a negative outcome of child maltreatment , remains one of the least understood phenotype . while most previous studies into rad have been conducted among romanian orphans and are limited to children younger than 6 years ( for reviews ) , a few studies have recently demonstrated that rad symptoms are reliably identifiable in children older than 6 years . historically , rad ( or attachment disorders ) was initially defined as a psychiatric disorder in the dsm - iii and associated with attachment insecurity as first proposed in bowlby 's attachment theory . now , it is doubted that rad is closely associated with attachment insecurity in terms of classic attachment theory . although rad and dsed were defined as two subtypes ( inhibited and disinhibited types ) of the same disorder in the dsm - iv criteria , they are now divided into two distinct disorders based on the dsm - 5 criteria . according to the dsm - 5 , children with rad exhibit wary , watchful , and emotionally withdrawn behaviours , whereas children with dsed display clingy and indiscriminately friendly behaviours even in their interactions with unfamiliar adults . it may also co - occur with asd , intellectual developmental disorder , or depressive disorders . although the presence of asd is considered an exclusionary condition for diagnosing rad in the dsm - 5 , the clinical differential diagnosis is complicated by clinical correlates of rad with quasi - autism . to enhance further our understanding of rad , it is of particular importance to investigate the nature of the neurobiological mechanisms underlying the behavioural problems of rad . previous neuroimaging studies using structural magnetic resonance imaging ( smri ) techniques have revealed that exposure to early adversity is strongly associated with alterations in brain structure , such as in the grey matter ( gm ) and white matter ( wm ) ( for reviews ) . according to teicher and samson , many of the identified neuroanatomical abnormalities are interconnected , and are components of a neurocircuit regulating the stress response to emotional stimuli that includes the thalamus , visual or auditory sensory cortex , medial prefrontal cortex , hippocampus , and amygdala . while the majority of smri studies predominantly focus on a priori hypothesised regions and thus provide a constrained characterisation of anatomy , studies into child maltreatment using an unbiased whole - brain analysis approach have been increasingly conducted and have reported similar results as shown in region - of - interest ( roi ) studies . as for other regionsnot commonly examined in roi studies , structural abnormalities in the thalamus and sensory cortex have been revealed for the first time by using such an unbiased whole - brain analysis approach . this approach is helpful to understand the unknown neurobiological abnormalities in rad associated with child maltreatment . the aim of this study was to identify structural alterations in regional gm volume ( gmv ) in maltreated children with rad using voxel - based morphometry ( vbm ) as an unbiased whole - brain analysis approach . we sought to assess further whether alterations in regional gmv correlated with psychiatric symptom measures . we hypothesised that rad , as a negative outcome of child maltreatment , would be associated with alterations in the brain regions that are part of a neurocircuit regulating the stress response to emotional stimuli . given the general pattern of findings in the related fields , we predicted that subjects with rad , compared to controls without rad , would be associated with reduced gmv in the thalamus , visual occipital cortex , and prefrontal cortex , and with increased gmv in the auditory temporal cortex . there would not be differences in gmv in the amygdala and hippocampus , especially in the child samples . the study protocol , approved by the ethics committees of the university of fukui , japan ( assurance no . fu2343 ) , was conducted in accordance with the declaration of helsinki and the ethical guidelines for clinical studies of the ministry of health , labour and welfare of japan . all children and a parent or director of child welfare facilities gave written informed assent and consent for participation in this study . twenty - one right - handed medication - naive 10 - to 17 - year - old japanese children ( mean age = 12.76 years ) with a clinical diagnosis of rad were recruited from the department of child and adolescent psychological medicine at the university of fukui hospital from august 2013 to december 2014 . the diagnosis of rad was assessed by licensed child and adolescent psychiatrists ( 2nd , 6th , and 8th authors ) according to the dsm - 5 criteria . to exclude other psychiatric conditions ( e.g. ptsd , anxiety disorder , and depression ) , subjects were administered the mini - international neuropsychiatric interview for children and adolescents ( mini - kid ) and an assessment module of dsm - iv adhd taken from the schedule of affective disorders and schizophrenia for school - age children , epidemiologic version ( k - sads - e ) by two licensed paediatric - psychological clinicians ( 2nd and 3rd authors ) . all of the children had experienced physical , emotional abuse , and / or neglect early in life prior to coming into care . the children were living within a stable placement ( in a child welfare facility ) even though they were not living with biological parents ( for information about child welfare services in japan ) . the control subjects , which included 22 typically developing ( td ) japanese children ( mean age = 12.95 years ) with no history of maltreatment , were recruited from local schools , matched on age , gender , and handedness . there was no difference in the proportion of subjects with corrected vision ( for myopia ) between the td ( 23 % ) and rad ( 24 % ) groups . children were excluded if they had a full scale intelligence quotient ( fsiq ) 70 on the wechsler intelligence scale for children ( wisc ) or the wechsler adult intelligence scale , and left - handedness according to the edinburgh handedness inventory . they were also excluded if they had any history of substance abuse , recent substance use , head trauma with loss of consciousness , significant foetal exposure to alcohol or drugs , perinatal or neonatal complications , neurological disorders , or medical conditions that might adversely affect growth and development . the depression self - rating scale for children ( dsrsc ; ) , an 18 - item self - report measure , was used to measure depressive symptoms . the trauma symptom checklist for children ( tscc ; ) , a 54 - item self - report measure , was used to evaluate post - traumatic symptoms and other relevant symptoms found in some traumatised children ( anger , anxiety , depression , post - trauma stress , dissociation , and sexual concerns ) . parents or caregivers in the facilities also completed the strength and difficulties questionnaire ( sdq ; ) , a 25 - item questionnaire , to assess children 's internalising and externalising behaviour problems , as well as prosocial behaviour tendencies . the sdq internalising behaviour problems are found to be associated with a measure of anxiety symptoms in a sample of children with anxiety disorder , which resembles rad due to emotional regulation impairments . a positive association between the sdq and relationship problems questionnaire ( rpq ) scores has been previously reported . the adhd rating scale ( adhd - rs ; ) , an 18 - item questionnaire , was used to evaluate inattentive and hyperactive / impulsive symptomsthe autism spectrum quotient ( aq ) , a 50 - item questionnaire , was completed by a parent or caregiver to evaluate asd traits , such as social skills , attention switching , attention to detail , communication , and imagination . all subjects were scanned on a 3 - tesla mr scanner ( discovery mr 750 ; general electric medical systems , milwaukee , wi , usa ) with a 32 - channel head coil . high - resolution structural whole - brain images were acquired by a 3d t1 - weighted fast spoiled gradient recalled imaging sequence ( repetition time ( tr ) = 6.38 ms ; echo time ( te ) = 1.99 ms ; flip angle ( fa ) = 11 ; field of view ( fov ) = 256 mm ; 256256 matrix ; 172 slices ; voxel dimension = 1.01.01.0 mm ) . the vbm was performed using statistical parametric mapping ( spm ) version 12 software ( wellcome department of imaging neuroscience , london , uk ) implemented in matlab r2014a ( mathworks , natick , ma , usa ) . as a fully automated whole - brain morphometric technique , vbm detects regional structural differences between groups on a voxel - by - voxel basis . the t1 - weighted images were preprocessed using the vbm approach with modulation , where the images were first segmented into gm , wm , cerebrospinal fluid , and skull / scalp compartments . the diffeomorphic anatomical registration through an exponentiated lie algebra ( dartel ) algorithm was applied to the segmented brain tissues to generate a study - specific template and to achieve an accurate inter - subject registration with improved realignment of smaller inner structures . the segmented gm images were spatially normalised into montral neurological institute ( mni ) space and were written out with an isotropic voxel resolution of 1.5 mm . any volume change induced by normalisation was adjusted via a modulation algorithm . the normalised modulated gm images were smoothed by a gaussian kernel of 8 mm full width at half maximum ( fwhm ) . regional differences in gm volume ( gmv ) between groups were analysed in spm 12 using two - sample t - test models . potential confounding effects of age , gender , fsiq , and total brain volume ( calculated as the sum of gmv and wm volume ( wmv ) ) were modelled , and variances attributable to them were excluded from the analyses . a gm majority optimal threshold mask , based on a study - specific sample , was applied to the analyses to eliminate voxels of non - gm for the gmv - analyses . the resulting set of voxel values used for comparison generated a statistical parametric map of t - statistic , spm { t } , that was transformed to a unit normal distribution ( spm { z } ) . the statistical threshold was set at p 0.05 with correction for multiple comparisons at cluster level ( height threshold of z 3.09 ) because of the increased sensitivity of clusters to detect spatially extended signal changes . potential problems relating to non - isotropic smoothness , which can invalidate cluster level comparisons , were corrected by adjusting cluster size from the resel per voxel image . the anatomical localisation of significant clusters was investigated with the automated anatomical labeling ( aal ) and brodmann area ( ba ) atlases implemented in the mricron software package . significant clinical differences between the td and rad groups complicated the exploration of post hoc functional correlates between the vbm - identified cluster in the statistical models ( controlling for age , gender , fsiq , and total brain volume ) and psychiatric symptom measures . hence , multiple regression analyses were carried out to further inspect which psychiatric symptom measures could significantly predict gmv in the identified cluster . to this end , the eigenvariates , representing linearly transformed estimates of gmv , were extracted from the identified cluster in the statistical models . in the multiple regression analyses , several psychiatric symptom measures showing significant between - group differences were treated as independent variables , and the gmv estimates in the relevant cluster for the entire sample and each group were treated as dependent variables . the multiple regression analyses were performed using the statistical package for the social sciences 22 software ( spss , chicago , il , usa ) . bonferroni adjustment for multiple regressions was applied when multiple regressions were made on the measures . the two groups were matched in age , gender , and handedness . for between - groupcomparison of fsiq and psychiatric symptom measures , we used analysis of covariance ( ancova ) with age and gender as covariates . in comparison with the td group , the rad group showed lower fsiq ( f = 8.78 , p .01 ) and higher levels of psychiatric symptom measures : depressive symptoms ( dsrsc ; f = 9.86 , p .01 ) ; post - traumatic symptoms , and other relevant symptoms ( tscc ) , such as anxiety ( f = 6.14 , p .05 ) ; depression ( f = 8.80 , p .01 ) ; anger ( f = 8.93 , p .01 ) ; post - trauma stress ( f = 10.53 , p .01 ) ; and dissociation ( f = 11.34 , p .01 ) . as for the parent - or caregiver - rating questionnaire for psychiatric symptoms , similar differences ( td rad ) were found in measures of sdq internalising ( f = 15.72 , p .001 ) and externalising problems ( f = 12.13 , p .01 ) , adhd symptoms ( adhd - rs total , f = 10.86 , p .01 ; inattentive , f = 12.64 , p .01 ; hyperactive / impulsive , f = 4.83 , p .05 ) , and asd traits ( aq total , f = 7.28 , p .05 ; attention switching , f = 15.61 , p .001 ; communication , f = 9.98 , p .01 ) . no subject met the criteria for bipolar disorder , adhd , or asd as all of the scores were under the threshold for the clinical criteria . we estimated absolute global volumes , that is , gmv ( 789.0673.19 ml and 749.8858.97 ml ) , wmv ( 396.2148.93 ml and 378.1331.43 ml ) , and total brain volume ( 1185.28113.40 ml and 1128.0185.29 ml ) in the td and rad groups , respectively . no differences between the two groups were found for each global volume . a whole - brain analysis with fwe correction at cluster levelthe rad group , in comparison with the td group , showed reduced gmv in the left primary visual cortex ( ba17 ; mni coordinates , x = 20 , y = 74 , z = 8 ; cluster size = 644 voxels , p = .038 , fwe - corrected cluster level ; fig .1 ) . a 20.6 % average reduction of gmv was found in the identified regions of the rad group compared with the td group . to confirm the trend of the occipital gmv reductionfurther , we used a lower criterion for statistical significance ( marginal significance level ) . the left inferior occipito - temporal cortex ( i.e. fusiform gyrus ; ba19 / 37 ; mni coordinates , x = 30 , y = 47 , z = 11 ; cluster size = 310 voxels ) exhibited a marginally significant decrease in gmv in the rad group relative to the td group ( p = .072 , fwe - corrected cluster - level ) . overall , reduced gmv in the rad group was shown in the left side of the occipital ( visual ) cortex extending anteriorly toward the inferior occipito - temporal cortex . we then performed multiple regression analyses to further characterise the relationship between psychiatric symptom measures and gmv in the left visual cortex identified by the whole - brain analysis . the gm eigenvariates ( i.e. linearly transformed estimates of gmv ) from the identified cluster were extracted and used for regression analyses . as indicated in table 2 , the analysis showed that the psychiatric symptom measures for sdq internalising problems ( = 0.96 , t = 3.86 , p .05 ) were a significant predictor for the left visual cortex gmv estimates in the rad group , which explained approximately 55 % of the variance of the gmv ( adjusted r = .55 , f = 3.16 , p .10 ) . except for the sdq internalising problemssuch a relationship between the measures and the gmv estimates was not seen in the entire sample or the td group . furthermore , additional correlation analyses were conducted to examine whether the left visual cortex gmv of the rad group was associated with the wisc factor index scores indicating children 's cognitive abilities , such as verbal comprehension , perceptual reasoning , working memory , and processing speed . there was no significant association of the gmv estimates with each wisc factor index score ( all ps alterations in the visual cortex gmv of the rad group were not associated with cognitive ability measures . the present study provides the first evidence demonstrating that children and adolescents with rad exhibit structural abnormalities in the left primary visual cortex ( ba17 ) . a smaller visual cortex gmv was observed in the rad group compared to the td group . further analysis exhibited a negative correlation of the visual cortex gmv of the rad group with sdq internalising problems , but not with other psychiatric symptom measures ( e.g. sdq externalising problems ) or cognitive ability measures ( wisc factor index scores ) . our results are consistent with previous findings reported in adults with histories of childhood maltreatment . although many studies into the effects of early adversity adopted a constrained roi approach and did not report results for the visual cortex , some studies using an unbiased whole - brain approach have found a smaller visual cortex gmv in young adults with episodes of childhood sexual abuse or witnessing domestic violence . in an earlier study , reduced occipital gmvwas also associated with a priori history of child abuse but not with victims of intimate partner violence . reportedly , the visual cortices that process and convey the adverse sensory input of childhood maltreatment , such as sexual abuse and witnessing domestic violence , appear to be specifically modified by this experience . these findings fit with preclinical studies showing that the visual cortex is a highly plastic structure . hence , early adverse experiences ( e.g. sensory deprivation ) may affect the development of the primary visual system , reflecting in the size of the visual cortex in children and adolescents with rad . the visual cortex has been viewed as part of a neurocircuit that regulates the stress response to emotional visual images . through the inferior longitudinal fasciculus ( ilf ) , the primary visual cortex and limbic system ( e.g. amygdala , hippocampus ) are anatomically connected . the ilf , ( i.e. visual - limbic pathway ) subserves emotional functions specific to the visual modality . based on this anatomical connection ( i.e. the ilf ) , the primary visual cortex conveys emotional signals ( e.g. fearful sights ) to the amygdala and receives feedback signals from the amygdala . in functional mri studies , a connectivity analysis has revealed that the effect of the amygdala on behaviour to emotional visual stimuli was mediated through backward projections from the amygdala to the visual cortex . furthermore , this visual - limbic pathway seems to be negatively affected by exposure to early life stress . in a recent smri study using a diffusion tensor imaging ( dti ) technique , a reduction in the wm tract integrity of the left ilf interconnecting the visual cortex to the limbic systemwas reported in a sample of young adults who witnessed interparental violence during childhood and of children with exposure to maltreatment . alterations in the development of the left visual cortex connected via the ilf may play a critical role in the occurrence of rad where the child displays emotionally withdrawn behaviours . that the gmv abnormalities may play a critical role in rad symptoms is also supported by the present results of the multiple regression analysis that showed an association between the visual cortex gmv of the rad subjects and their internalising problems ( sdq internalising ) when incorporating other relevant factors ( e.g. sdq externalising ) into the multiple regression model . as addressed in the introduction section , rad is considered in the dsm - 5 to resemble internalising disorders with depressive and anxiety symptoms . because of emotional dampening in rad , it is also reasonable to consider a potential convergence between rad symptoms and internalising problems . while the sdq internalising problems are likely to reflect inhibited rad symptoms , they seem to be associated with other questionnaire scores for rad symptoms . subscales of the sdq internalising measure ( emotional and peer problems ) have been associated with the inhibited behaviour subscale of the rpq as a useful but limited instrument for screening inhibited and disinhibited rad symptoms . why the left - sided hemisphere of the visual cortex was affected is an interesting question . given that rad patients show reduced or absent expression of positive emotions during routine interactions with caregivers , we propose that the reduction of gmv in the left visual cortex identified here may be associated with a malfunction in the neurocircuit regulating positive emotional visual images ( e.g. a smiling face ) . in line with our proposal , it has been reported that children exposed to child adversity have difficulty recognising positive emotional expressions . indeed , the processing of positive emotion has been proposed to be associated with the left hemisphere , although hemispheric lateralisation in emotion processing remains controversial between the valence hypothesis and the right hemisphere hypothesis ( e.g. ) . according to the valence hypothesis , which is the currently leading hypothesis in emotion processing , the left hemisphere is specialised for positive emotions and the right is dominant for negative emotions . more recently , behavioural studies using a divided visual field paradigm have found support for this hypothesis , showing that positive emotions were better recognised when presented in the right visual field and negative emotions were better identified when presented in the left visual field ( e.g. ) . a neurophysiological study using event - related potentials has also found that processing of the mouths of happy faces ( i.e. analytical or part - based processing of positive emotional expressions ) enhanced left - sided occipito - temporal activity during the early visual processing phase . combined with a previous dti study showing that the left - sided ilf wm abnormalities were associated with early adversity , we suggest that the left - sided visual cortex gm abnormalities may lead to a difficulty with regulating positive emotions in rad . only one brain region , the left occipital visual cortex , was affected by the symptoms of rad in the present smri study . however , this does not mean that other regions of the neurocircuit that regulates emotion were not associated with child maltreatment and other psychiatric disorders . the related prefrontal and temporal cortices seem to be associated more with ptsd than rad , which are both incorporated into the same category of trauma - and stressor - related disorders in the dsm - 5 . as suggested by a quantitative meta - analysis of gmv changes in ptsd , the prefrontal and temporal cortices were likely to be disease - related and disconnected frommoreover , in child smri studies using unbiased whole - brain morphometric comparisons , alterations in the left thalamus have been involved in the association between child maltreatment and the occurrence of generalized anxiety disorder . although generalized anxiety disorder resembles rad due to emotional regulation impairments , the neural vulnerability markers of these psychiatric disorders may differ regardless of the histories of child maltreatment . for the limbic system ( hippocampus and amygdala ) , there appears to be differences in maltreatment effects on brain structure between studies of children and adults , with gmv alterations being previously observed in adults but not in children . these findings suggest that maltreatment has differentiated effects on brain structure across the development and reorganisation processes . another possibility may be tied to an association between specific maltreatment type and abnormalities in the limbic system . in a recent smri study , the gmv reduction in the limbic system was associated with children exposed to only a single type of maltreatment ( physical abuse , neglect ) but not to multiple complex types of maltreatment . furthermore , it should be noted that adhd has been associated with altered occipital gmv . as adhd symptomshave not been associated with rad , but have been with dsed , there seems to be partially overlapping structural abnormalities in these psychiatric disorders . in this study , however , no subject had a history of adhd . thus , the reduced occipital gmv of the rad group identified here can not be explained by specific cognitive dysfunctions based on adhd , such as visual attentional dysfunction in adhd related to the occipital visual cortex . although we have discussed this finding in terms of a potential cause and effect mechanism , it must be emphasised that our evidence only supports an association between emotional dysfunction and current symptoms of radalthough a sample size of at least twenty in each group is desirable for reliability in between - group comparisons , studies involving a larger number of subjects are essential to generalise our results . second , whole - brain analysis approaches are limited by the need to adjust for multiple comparisons to minimise the risk of detecting chance - related differences . consequently , only the most robust differences in brain structure tend to emerge . third , the present study used a cross - sectional design that precludes the identification of causal links between rad and the gmv differences . longitudinal studies are needed to investigate how the structural differences associated with rad change with intervention programs aimed at diminishing the signs of rad . other cross - sectional designs adopting different comparison groups of maltreated children without rad would also be helpful to better understand the neurobiological consequences of rad . fourth , as seen in table 1 , there were substantial iq differences in our study , with the rad group showing a lower fsiq compared to the td group as previously reported in child maltreatment studies . however , we used statistical methods to control for these confounds and adjusted for the fsiq in the vbm analysis . fifth , the subjects ' pubertal stages were not assessed in this study . while chronological age has been associated with pubertal stage , recent evidence from studies of the developing brain has suggested that pubertal stage might play a more important role in adolescent brain development than chronological age ( e.g. ) . future studies are needed to elucidate whether pubertal stage has a differentiated effect on brain development across the samples . a more robust diagnosis needs to be based on ecological observation of the child 's interaction activity in a local school or community , as well as on clinical interview and questionnaire data . it is also suggested that the phenotype of rad in the dsm - 5 may be further encompassed within a broader phenotype . nevertheless , this study sheds light on the neural underpinning of emotional dysregulation as a core symptom of rad . we provide novel evidence that structural abnormalities in the left occipital visual cortex were associated with children and adolescents with rad . furthermore , the internalising problems of rad correlated with the identified visual cortex gmv . combined with previous studies of adults with childhood maltreatment , early adverse experience ( e.g. sensory deprivation ) may affect the development of the primary visual system , reflecting in the size of the visual cortex in children and adolescents with rad . these visual cortex gmv abnormalities may also be associated with the visual emotion regulation impairments of rad , leading to an increased risk for later psychopathology .\noutput:\n" }, { "from": "agent", "value": "child maltreatment increases the risk for psychiatric disorders throughout childhood and into adulthood . one negative outcome of child maltreatment can be a disorder of emotional functioning , reactive attachment disorder ( rad ) , where the child displays wary , watchful , and emotionally withdrawn behaviours . despite its clinical importance , little is known about the potential neurobiological consequences of rad . the aim of this study was to elucidate whether rad was associated with alterations in grey matter volume ( gmv ) . high - resolution magnetic resonance imaging datasets were obtained for children and adolescents with rad ( n = 21 ; mean age = 12.76 years ) and typically developing ( td ) control subjects ( n = 22 ; mean age = 12.95 years ) . using a whole - brain voxel - based morphometry approach , structural images were analysed controlling for age , gender , full scale intelligence quotient , and total brain volume . the gmv was significantly reduced by 20.6 % in the left primary visual cortex ( brodmann area 17 ) of the rad group compared to the td group ( p = .038 , family - wise error - corrected cluster level ) . this gmv reduction was related to an internalising problem measure of the strength and difficulties questionnaire . the visual cortex has been viewed as part of the neurocircuit regulating the stress response to emotional visual images . combined with previous studies of adults with childhood maltreatment , early adverse experience ( e.g. sensory deprivation ) may affect the development of the primary visual system , reflecting in the size of the visual cortex in children and adolescents with rad . these visual cortex gmv abnormalities may also be associated with the visual emotion regulation impairments of rad , leading to an increased risk for later psychopathology ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the flexion - relaxation phenomenon ( frp ) is the myoelectric silencing of a muscle during a full - flexion maneuver1 . the frp of the erector spinae ( es ) muscles shows silencing during upright to full - flexion lumbar movement in asymptomatic subjects . the phenomenon involves the transfer of the role of the extension moment producer to the deep back muscles to achieve spinal stability2 . patients with low back pain ( lbp ) exhibit laxity of passive structures and an altered neuromuscular activation pattern in the back muscles , in which the frp of the es muscles is not present . thus , the frp of es muscles has been used to evaluate lbp and to monitor intervention - related factors after treatment3 . previous studies have shown that frp occurs with full lumbar flexion in the sagittal plane . however , asymptomatic and symptomatic subjects can produce asymmetric lumbar flexion by lumbar flexion combined with lateral bending and axial rotation . although most healthy people do not have lbp , they have the potential for asymmetry in the frp in the right and left es muscles due to repetitive movement and poor posture in their work environments or daily activities . ning et al. 4 reported that asymmetric lumbar flexion elicits a loss of the frp in the ipsilateral muscle in asymptomatic subjects . although 90 % of non - lbp subjects show frp5 , many of them were at risk of lbp , because of asymmetry in the frp of the es muscles . currently , lbp patients perform various deep muscle strengthening exercises for lumbar tissue , with pilates , sling exercises , and lumbar stabilization exercises being the most common6 . lumbar stabilization exercises , especially the back bridge and hand - knee position , are the most effective at strengthening the multifidus muscle7 . marshall and murphy et al. 3 reported that a 12 - week exercise program ( side bridge , supine bridge , partial curl - up , bird - dog exercise , swiss ball push - up , single leg hold , and rollouts ) decreased self - reported pain and es muscle activity during the relaxation phase of frp tests in patients with chronic non - specific lbp . lumbar stabilization exercises elicit a reappearance of the frp through strengthening of the multifidus muscle , and eventually this could result in symmetry of the frp in non - lbp subjects with an asymmetric frp of the es muscles . the purpose of this study was to evaluate differences in the frp in the right and left es muscles in asymptomatic subjects . in addition , the effects of lumbar stabilization exercises on differences in the frp of the right and left es muscles were investigated . participants ( n = 30 ; average age , 19.81.1 years ; height , 164.57.4 cm ; body mass , 57.547.20 kg ) were recruited from among the healthy student population of silla university . participants were excluded from the study if they had a history of back pain , vertebra surgery , or neuromuscular disorders . all procedures were reviewed and approved by the ethics committee of silla university . to analyze the frp of the es muscles , surface electromyography ( emg ) ( myotrace 400 ; noraxon inc . , scottsdale , az , usa ) was used with two bipolar surface emg electrodes placed bilaterally 2 cm apart over the right and left l3 area . the data were collected at 1,000 hz and processed using a 20450 hz band - pass filter and a 60 - hz notch filter . the root mean square moving average of 300 ms duration of the processed emg data was calculated . the relaxation time was defined as when es activation decreased by two standard deviations ( sd ) of silence activation in the fully flexed lumbar phase . the absolute value of the difference in relaxation time measured in the right and left es was calculated . the experiment was done in triplicate and the calculations were based on the averages of the three trials . the position of the feet was marked for consistency between trials . in all trials , the move from upright to full - forward flexion ( forward flexion phase ) was performed over 3s , followed by 3s maintenance of full flexion posture ( fully flexed phase ) , and another 3 s to move from full - forward flexion to the upright posture ( re - extension phase ) 8 , 9 . participants were assigned randomly to the control or exercise group using a table of random numbersthe exercise group performed two exercises that are commonly used in clinical practice and have been used in previous studies ( back bridge and hand - knee exercise ) . these exercises were performed 3 days per week with a trainer and 2 days per week at home for 4 weeks . the exercises were done in three sets with three repetitions per set and a set break of 3 min . instructors provided feedback to ensure that a consistent supine and lower limb posture was maintained during the exercise . for the back bridge exercise , the subjects lay supine on the floor with their feet flat on the ground , their knees bent at 90 , their toes facing forward , and their hands on the floor by their sides . with their palms facing down , the subject raised the pelvis to achieve and maintain a neutral hip flexion angle . the subjects were requested to raise the back bridge from the floor ( stable condition ) and hold the posture for 1 min . after the 1 - min hold , the subject was given a 30 - s break . for the hand - knee exercise , the subjects started on their hands and knees with a neutral pelvis position and breathing normally . they lifted and held straight the right arm and the left leg before doing the same with the opposite set of limbs . the subjects held each position for 40 s with a 30 - s break between positions .18.0 ) was used to test the significance of differences between the exercise and control groups and between pre - and post - exercise . a subject factor analysis was used to assess the statistical significance of the frp in the es muscles with a repeated two - way analysis of variance . the paired t - test was used to test the significance of differences between the two groups characteristics . a difference was seen in the frp between the right and left es muscles in asymptomatic subjects ( control group 119.269.2 ms and exercise group 131.185.2 ms ; p 0.05 ) . the exercise group showed a significant decrease post - exercise ( 50.027.0 ms ) versus pre - exercise ( 112.341.5 ms ) in the right and left frp of the es muscles ( p 0.05 ) . in this study , the healthy participants showed a difference in the right and left frp in the es muscles . this lack of balance in the frp is thought to result from repetitive asymmetric posture and activity . previous research has indicated there is an increased risk of back pain when working in asymmetric positions9 . motor control deficits and motor dysfunction result in increased passive system loading from repeated stress10 . the students who participated in this experiment spent a great deal of time at school in a sitting position . this does not produce lbp , but they exhibited an asymmetric frp in the right and left es muscles . callaghan11 reported a difference in activation between the right and left es in healthy subjects ( right 15 and left 17 of 20 participants ) . this indicates that asymptomatic people can have impairment and imbalance in the frp . when the students exhibited poor posture ( e.g. , sitting cross - legged or one - leg weighted standing ) they experienced no pain , but they demonstrated potential factors for lbp . the bridge exercise is a popular lumbar stabilization exercise that activates weak abdominal muscles and prevents unstable lumbar spine movement via co - activation of the pelvic floor muscles , diaphragm , and deep abdominal muscles12 . additionally , the swiss ball exercise activates deep and superficial abdominal muscles by using the characteristics of an unstable environment13 . marshall and murphy14 reported that swiss ball exercises increased the frp ( from 3.263.43 to 6.533.34 ) in lbp patients . in the present study , lumbar stabilization exercises improved muscular balance by reducing asymmetry in frp onset . howarth et al. 15 reported that back muscle instability caused by slumped sitting delayed the onset of the frp . likewise , the intervention used in the present study was meaningful for trunk asymmetry and instability . at the onset of the frp , the external moment generated around the lower back by the upper body s mass is counteracted by the net internal moment produced from the tensile forces developed in elongated passive tissue , instead of the forces generated by the active component of the lower back musculature16 . thus , lumbar stabilization exercises can improve the motor control of lumbar spinal movement and lumbar stabilization control . among the various exercises used for lumbar stabilization , the sling and swiss ball exercises show the highest emg activation values17 ; however , this study used the back bridge and hand - knee exercises . these two exercises do not need any special equipment or space , so they are more suited for home - based exercise than sling or ball exercises . additional studies are needed to measure changes in the frp in the es muscles elicited by other lumbar stabilization exercises . while further study is needed , the results of this study suggest that lumbar stabilization exercises can help to correct asymmetry of the frp in the right and left es muscles and this would help prevent lbp in the general population .\noutput:\n" }, { "from": "agent", "value": "[ purpose ] this study evaluated the differences in the flexion - relaxation phenomenon ( frp ) of the right and left erector spinae muscles in asymptomatic subjects and the effect of lumbar stabilization exercises on these differences . [ subjects and methods ] twenty - six participants ( 12 in the exercise group and 14 in the control group ) with a difference in the frp in the right and left erector spinae muscles were recruited from among healthy students attending silla university . the exercise group performed two lumbar stabilization exercises ( back bridge exercise and hand - knee exercise ) for 4 weeks . the control group did not exercise . [ results ] no significant group - by - exercise interaction was found . the right and left erector spinae muscles did show a difference in frp between the control and exercise groups ( 119.2 69.2 and 131.1 85.2 ms , respectively ) . in addition , the exercise group showed a significant decrease in post - exercise ( 50.0 27.0 ms ) compared to pre - exercise ( 112.3 41.5 ms ) differences in the right and left frp . [ conclusion ] these results suggest that lumbar stabilization exercises may counter asymmetry of the frp in the erector spinae muscles , possibly preventing low back pain in the general population ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the diagnosis of disease involves several levels of uncertainty and imprecision , and it is inherent to medicine . a single disease may manifest itself quite differently , depending on the patient , and with different intensities . a single symptom may correspond to different diseases . on the other hand , several diseases present in a patient may interact and interfere with the usual description of any of the diseases . the best and most precise description of disease entities uses linguistic terms that are also imprecise and vague . moreover , the classical concepts of health and disease are mutually exclusive and opposite . however , some recent approaches consider both concepts as complementary processes in the same continuum . according to the definition issued by the world health organization ( who ) , health is a state of complete physical , mental , and social well - being , and not merely the absence of disease or infirmity . the loss of health can be seen in its three forms : disease , illness , and sickness . to deal with imprecision and uncertainty , we have at our disposal fuzzy logic . fuzzy logic introduces partial truth values , between true and false . according to aristotelian logic , for a given proposition or state we only have two logical values : true - false , black - white , 1 - 0 . in real life , things are not either black or white , but most of the times are grey . thus , in many practical situations , it is convenient to consider intermediate logical values . everybody is healthy to some degree h and ill to some degree i. if you are totally healthy , then of course h = 1 , i = 0 . usually , everybody has some minor health problems and h 1 , but ( 1 ) h + i = 1 . in the other extreme situation , h = 0 , and i = 1 so that you are not healthy at all ( you are dead ) . in the case you have only a broken nail , we may write h = 0.999 , i = 0.001 ; if you have a painful gastric ulcer , i = 0.6 , h = 0.4 , but in the case you have a terminal cancer , probably i = 0.95 , h = 0.05 . as we will see , this is a particular case of kosko 's hypercube : the one - dimensional case . uncertainty is now considered essential to science and fuzzy logic is a way to model and deal with it using natural language . since uncertainty is inherent in fields such as medicine and massive data in bioinformatics , and fuzzy logic takes into account such uncertainty , fuzzy set theory can be considered as a suitable formalism to deal with the imprecision intrinsic to many biomedical and bioinformatics problems . fuzzy logic is a method to render precise what is imprecise in the world of medicine . the complexity of medical practice makes traditional quantitative approaches of analysis inappropriate . in medicine , the lack of information , and its imprecision , and , many times , contradictory nature are common facts . medical history of the patient , which is usually supplied by the patient and / or his / her family . the physician usually obtains objective data , but in some cases the boundary between normal and pathological status is not sharp . results of laboratory and other diagnostic tests , but they are also subject to some mistakes , and even to improper behavior of the patient prior to the examination . the patient may include simulated , exaggerated , understated symptoms , or may even fail to mention some of them . we stress the paradox of the growing number of mental disorders versus the absence of a natural classification . the classification in critical ( ie , borderline ) cases is difficult , particularly when a categorical system of diagnosis is considered . fuzzy logic plays an important role in medicine . to predict the response to treatment with citalopram in alcohol dependence . to analyze diabetic neuropathy and to detect early diabetic retinopathy . to determine appropriate lithium dosage . to calculate volumes of brain tissue from magnetic resonance imaging ( mri ) , and to analyze functional mri data . to characterize stroke subtypes and coexisting causes of ischemic stroke . to improve decision - making in radiation therapy . to control hypertension during anesthesia . to determine flexor - tendon repair techniques . to detect breast cancer , lung cancer , or prostate cancer . to assist the diagnosis of central nervous systems tumors ( astrocytic tumors ) to discriminate benign skin lesions from malignant melanomas . to visualize nerve fibers in the human brain . to represent quantitative estimates of drug use . to study the auditory p50 component in schizophreniamany other areas of application , to mention a few , are to study fuzzy epidemics , to make decisions in nursing , to overcome electroacupuncture accommodation . to study fuzzy epidemics , to make decisions in nursing , to overcome electroacupuncture accommodation . the data is from 1991 to 2002 and includes also the number of those publications in 1990 and before . it results in a total of 804 articles and agrees essentially with the numbers indicated in . we plan to screen databases in the engineering literature that covers medicine - related articles since it is difficult to publish medical results using a fuzzy logic approach . in the future we will compare the figures obtained . figure 1 indicates an exponential growth in the number of articles in medicine making use of fuzzy technology . this data can consist of the information stored in the genetic code , and also experimental results ( and hence imprecision ) from various sources , patient statistics , and scientific literature . bioinformatics combines computer science , biology , physical and chemical principles , and tools for analysis and modeling of large sets of biological data , the managing of chronic diseases , the study of molecular computing , cloning , and the development of training tools of bio - computing systems . bioinformatics is a very active and attractive research field with a high impact in new technological development . molecular biologists are currently engaged in some of the most impressive data collection projects . recent genome - sequencing projects are generating an enormous amount of data related to the function and the structure of biological molecules and sequences . other complementary high - throughput technologies , such as dna microarrays , are rapidly generating large amounts of data that are too overwhelming for conventional approaches to biological data analysis . we have at our disposal a large number of genomes , protein structures , genes with their corresponding expressions monitored in experiments , and single - nucleotide polymorphisms ( snps ) . for example , the embl nucleotide sequence database ( http://www.ebi.ac.uk/embl ) has increased in 12 months from 18.3 million entries comprising 23 gb ( release 71 , september 2002 ) to 27.2 million entries comprising over 33 gb ( release 76 , september 2003 ) as indicated in . handling this massive amount of data , in many cases imprecise and fuzzy , requires powerful integrated bioinformatics systems and new technologies . the following are some examples . to increase the flexibility of protein motifs . to study differences between polynucleotides . to analyze experimental expression data using fuzzy adaptive resonance theory . to align sequences based on a fuzzy recast of a dynamic programming algorithm . dna sequencing using genetic fuzzy systems . to cluster genes from microarray data . to predict proteins subcellular locations from their dipeptide composition using fuzzy k - nearest neighbors algorithm . to simulate complex traits influenced by genes with fuzzy - valued effects in pedigreed populations . to attribute cluster membership values to genes applying a fuzzy partitioning method , fuzzy c - means . to map specific sequence patterns to putative functional classes since evolutionary comparison leads to efficient functional characterization of hypothetical proteins . the authors used a fuzzy alignment model . to analyze gene expression data . to unravel functional and ancestral relationships between proteins via fuzzy alignment methods , or using a generalized radial basis function neural network architecture that generates fuzzy classification rules . to analyze the relationships between genes and decipher a genetic network . to process complementary deoxyribonucleic acid ( cdna ) microarray images . the procedure should be automated due to the large number of spots and it is achieved using a fuzzy vector filtering framework . to classify amino acid sequences into different superfamilies . in 1992 , kosko introduced a geometrical interpretation of fuzzy sets as points in a hypercube . in 1998 , helgason and jobe used the unit hypercube to represent concomitant mechanisms in stroke . indeed , for a given set ( 2 ) x = { x1 , , xn } , a fuzzy subset is just a mapping ( 3 ) : xi = , and the value ( x ) expresses the grade of membership of the element x x to the fuzzy subset . for example , let x be the set of persons of some population and let the fuzzy set be defined as healthy subjects . if john is a member of the population ( the set x ) , then , ( john ) gives the grade of healthiness of john , or the grade of membership of john to the set of healthy subjects . if is the fuzzy set that describes the grade of depression , then ( mary ) is the degree of depression of mary . thus , the set of all fuzzy subsets ( of x ) is precisely the unit hypercube i = , as any fuzzy subset determines a point p i given by p =( ( x1 ) , reciprocally , any point a = ( a1 , , an ) in generates a fuzzy subset defined by ( xi ) = ai , i = 1 , , n . nonfuzzy or crisp subsets of x are given by mappings x : x { 0,1 } , and are located at the 2 corners of the n - dimensional unit hypercube i. for graphic representations of the two - dimensional and three - dimensional hypercube , we refer to . given , ( 4 ) p = ( p1 , p2 , , pn ) , q = ( q1 , q2 , , qn ) in , not both equal to the empty set not both equal to the empty = ( 0,0 , ,0 ) , we define the difference between p and q as ( 5 ) d ( p , q ) = i = 1n | piqi | i = 1nmax { pi , qi } . of course d ( , ) = 0 . hypercubical calculus has been described in , while some biomedical applications of the fuzzy unit hypercube are given in . recently , the fuzzy hypercube has been utilized to study differences between polynucleotides and to compare genomes . we now present an example of the use of the fuzzy hypercube in a medical case of consumption of drugs . consider the following fuzzy variables : smoking and alcohol drinking . if you do not smoke , then your degree of being a smoker is evidently 0 . if you smoke , for example , six cigarettes per day , we say that your degree of being a smoker is 0.8 . see [ 63 figure 3.8 ] for a geometrical representation of the fuzzy concept of being a smoker . with respect to the other fuzzy variable , if you drink no alcohol , the degree of this variable is 0 . if you drink more than 75 cc of alcohol per day , the degree of alcoholism is 1 . for 25 cc / d , the degree could be 0.4 and for 50 cc / d , 0.8 . thus , the fuzzy set = ( 0 , 0 ) corresponds to a nonsmoker and teetotaler . some further examples are the following : the set = ( 1 , 0 ) represents a heavy smoker , but a teetotaler , and the set = ( 0.8 , 1 ) is a person who smokes about six cigarettes a day and is a risk consumer of alcohol . suppose you correspond to the fuzzy set = ( 1 , 1 ) , have recently had some health problems , and your physician has advised you to reduce your consumption of cigarettes and alcohol by half . the ideal situation for your health is , of course , the point = ( 0 , 0 ) , but it is possibly difficult to achieve . cigarette smoking and alcohol drinking during adolescence have been shown to be associated with a greater possibility of concurrent and future substance - related disorders ( lewinsohn etal ; nelson and wittchen ) . in order to report patterns of drug use and to describe factors associated with substance use in adolescents , a cross - sectional survey was carried out in a representative population sample of 2550 adolescents , aged 12 to 17 years , from galicia ( an autonomous region located in the northwest of spain ) . the original survey covered the use of alcohol , tobacco , illicit drugs , and other psychoactive substances . for tobacco smoking and alcohol drinking , each subject of the population sample was assigned a fuzzy degree of addiction ( or risk use ) and mapped into the two - dimensional hypercube i by an expert . for example figure 2 represents the number of subjects in the cross - sectional survey according to the two fuzzy degrees of addiction . the reader can see that there are 1278 subjects corresponding to the point ( 0,0 ) , that is , nonsmoker and teetotaler . there are 121 subjects on the line of probability x1 + x2 = 1 . indeed ( see figure 2 ) , 23 + 1 + 1 + 2 + 2 + 7 + 1 + 84 = 121 . this means that the vast majority of subjects ( 2429 / 255095.25 % ) are outside the line of probability . this is in agreement with the fundamental limitation of probability theory with respect to clinical science in general and agrees with its results ( 29/3096 .66 % ) . we refer to for details on the general theory of fuzzy midpoints and their applications . the complete genome sequence of mycobacterium tuberculosis h37rv is available at http://www.ncbi.nlm.nih.gov with accession number nc000962 . the genome comprises 4411529 base pairs , contains around 4000 genes , and has a very high guanine + cytosine content . computing the number of the nucleotides at the three base sites of a codon in the coding sequences of m tuberculosis ( table 2 ) , and then calculating the corresponding fractions , we have the fuzzy set of frequencies of the genome sequence of m tuberculosis ( table 3 ) . this set can be considered as a point in the hypercube i. indeed , the point ( 6 ) ( 0.1632 , 0.3089 , 0.1724 , 0.3556 , 0.2036 , 0.3145 , 0.1763 , 0.3056 , 0.1645 , 0.3461 , 0.1593 , 0.3302 ) i12 . aquifex aeolicus was one of the earliest diverging , and is one of the most thermophilic , bacteria known . it can grow on hydrogen , oxygen , carbon dioxide , and mineral salts . the complex metabolic machinery needed for a aeolicus to function as a chemolithoautotroph ( an organism which uses an inorganic carbon source for biosynthesis and an inorganic chemical energy source ) is encoded within a genome that is only one - third the size of the e coli genome . the corresponding data for a aeolicus was obtained from http://www.ncbi.nlm.nih.gov with accession number nc_000918 , and is presented in tables 4 and 5 , respectively . the fuzzy set of frequencies of the genome of a aeolicus is ( 7 ) 0.1706 , 0.1605 , 0.3241 , 0.3446 , 0.3282 , 0.1735 , 0.3478 , 0.1504 , 0.2139 , 0.2455 , 0.3052 , 0.2352 ) i12 . using the distance given in ( 5 ) , it is possible to compute the distance between these two fuzzy sets representing the frequencies of the nucleotides of a aeolicus and m tuberculosis : ( 8 ) d ( a aeolicus , m tuberculosis ) = 2.21256.1060.3623 . inwe calculate the difference between m tuberculosis and e coli k - 12 obtaining ( 9 ) d ( m tuberculosis , e coli ) = 0.85063.42530.2483 . using the corresponding data for e coli ( see [ 44 tables 3 and 3 ] ) , we get ( 10 ) d ( a aeolicus , e coli ) = 0.85145.01610.1697 . number of subjects in the two - dimensional fuzzy hypercube i. number of papers per year in medicine using fuzzy logic . number of nucleotides at the three base sites of a codon in the coding sequence of mycobacterium tuberculosis . fractions of nucleotides at the three base sites of a codon in the coding sequence of mycobacterium tuberculosis . number of nucleotides at the three base sites of a codon in the coding sequence of aquifex aeolicus . fractions of nucleotides at the three base sites of a codon in the coding sequence of aquifex aeolicus .\noutput:\n" }, { "from": "agent", "value": "the purpose of this paper is to present a general view of the current applications of fuzzy logic in medicine and bioinformatics . we particularly review the medical literature using fuzzy logic . we then recall the geometrical interpretation of fuzzy sets as points in a fuzzy hypercube and present two concrete illustrations in medicine ( drug addictions ) and in bioinformatics ( comparison of genomes ) ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: respiratory system sequelae are the most important long - term complications in patients exposed to sulfur mustard . thousands of iranian civilians and veterans are still suffering from delayed respiratory difficulties caused by inhalation of this toxic gas during the iraq conflict with iran more than 25 years ago .1,2 cough , dyspnea , excessive sputum production , and hemoptysis are among the most prominent chronic pulmonary symptoms in sulfur mustard - injured patients .3,4 nowadays , bronchiolitis obliterans is part of the diagnosis in these patients .5 however , a number of differences have been found between this kind of bronchiolitis obliterans and other kinds , such as that following lung transplantation , and there is no progression pattern , rare fibrosis , differing severity , and less obliteration .6 investigations have shown that the pulmonary disorder in patients with chronic sulfur mustard exposure is strongly associated with oxidative stress , caused by an imbalance between excessive creation of reactive oxygen and / or nitrogen species and depletion of endogenous antioxidants ,7 along with the release of several kinds of inflammatory mediators from a number of cell types .8,9 a recent study has shown that serum glutathione levels are significantly lower in patients exposed to sulfur mustard than in controls , but the level of malondialdehyde is significantly higher in sulfur mustard victims .10 more recently , in a study of airway biopsy samples , we demonstrated that expression of lipocalin - 2 at the mrna level was significantly higher in sulfur mustard - injured patients in comparison with controls , but there was no significant difference in the expression of lipocalin - 2 protein between patients and controls .11 these data confirm that oxidative stress due to excessive production of harmful reactive substances and decreased levels of endogenous protective antioxidants is a phenomenon in these patients that plays a pivotal role in the pathology of late pulmonary complications of sulfur mustard exposure . . metallothioneins ( mts ) are a group of low molecular weight ( 67 kda ) , sulfhydryl - rich intracellular proteins with 61 to 68 amino acid residues , initially recognized by margoshes and vallee in 1957 as cadmium - binding proteins in equine kidney tissue . in human beings , several mt isoforms , from mt - 1 through mt - 4 , have been identified .12 mt - 1 is an inducible mt isoform encoded by a group of more than 10 functional genes , amongst which mt - 1a is a broadly disseminated mt isoform in the human body . its transcription is activated by a variety of stress stimuli , including metals , glucocorticoids , a number of proinflammatory cytokines , and reactive oxygen species .13,14 intracellular metal homeostasis , heavy metal detoxification , and scavenging of a wide variety of compounds , including hydroxyl radicals , superoxide , hydrogen peroxide , and nitric oxide , are among the accepted roles of mt - 1 , although the exact molecular mechanisms involved are not fully understood .15,16 a number of studies have demonstrated coexpression of mt - 1 and lipocalin - 2 in some illnesses , including oxidative stress - mediated lung injuries .17 the present study aimed to assess the expression of mt - 1a at the mrna and protein levels in bronchial biopsy samples of sulfur mustard - injured patients in comparison with controls . our results may pave the way to new treatments for the chronic respiratory complications encountered in these patients . twenty - four sufferers of chronic respiratory sequelae from exposure to sulfur mustard during the 19801988 iraniraq war were enrolled as the sulfur mustard - exposed group and 15 unexposed individuals as the control group . contact with sulfur mustard was confirmed by documents from the iranian military health services at the time of exposure . these victims all developed pulmonary symptoms immediately after contact with sulfur mustard , without any symptom - free periods . the study was approved by the ethics committee of the baqiyatallah university of medical sciences . the procedures conformed to the guiding principles of the declaration of helsinki , and all subjects signed informed consent forms for participation in the study . potential subjects having other interactive criteria , as well as those involving other chronic pulmonary diseases ( eg , asthma ) , autoimmune disease ( eg , rheumatoid arthritis ) , lung cancer , diabetes mellitus , acute infective bronchitis , or pneumonia , were excluded . drug addicts , elderly people ( 65 years old ) , smokers , organ transplant recipients , and patients with a history of occupational pulmonary exposure to other toxic agents were also excluded . age , gender , and pulmonary function test data for the two groups are shown in table 1 . all subjects were anesthetized by inhalation of 2 % aerosolized lidocaine and intravenous midazolam , and slept lightly throughout the procedure . bronchoscopy was carried out using a flexible fiberoptic bronchoscope ( bf1 t ; olympus , tokyo , japan ) passed through the airway to reach the segmental and subsegmental carinae , and endobronchial biopsy specimens were taken from these regions using bronchoscopic forceps ( olympus ) . supplemental oxygen was given throughout the procedure , and oxygen saturation was checked at regular intervals by a pulse oximeter until the subjects regained consciousness . two biopsy samples were taken from each patient , and were immediately and separately immersed in tripure isolation reagent ( roche , mannheim , germany ) and formalin ( merck , darmstadt , germany ) . the samples in tripure were stored at 80c until rna extraction , and the formalin samples were kept at 4c for immunohistochemistry . we have already described the reverse transcriptase polymerase chain reaction procedure used in this study .11 in brief , all the rna contained in the airway biopsy specimens was harvested in tripure isolation reagent in accordance with the manufacturer s protocol and kept at 80c during the procedure . the rna extracted was evaluated by nanodrop spectrophotometer ( nd - 1000 ; wilmington , de ) , and its quality was confirmed by electrophoresis in 1 % agarose gel ( cinnagen , tehran , iran ) . aliquots of 500 ng of isolated rna were utilized as templates for cdna synthesis by superscript iii reverse transcriptase ( invitrogen , carlsbad , ca ) following the manufacturer s instructions . semiquantitative reverse transcriptase polymerase chain reaction for the mt - 1a gene was carried out using equal amounts of synthesized cdna , in a final reaction volume of 25 l . all reagents and recombinant taq dna polymerase were obtained from cinnagen , and the reactions were done in a master cycler thermal cycler . specific primers for mt - 1a and - actin ( as a housekeeping gene ) were designed using primer3 software ( http://frodo.wi.mit.edu/ ) and ordered from bioneer ( daejeon , south korea , see table 2 ) . the polymerase chain reaction conditions comprised primary denaturation at 94c for 5 minutes , followed by 30 polymerase chain reaction cycles comprising denaturation at 94c for 30 seconds , annealing at 59c ( both genes at the same temperature ) for 30 seconds , extension at 72c for 60 seconds , followed by 5 minutes of terminal extension at 72c . finally , the polymerase chain reaction products were electrophoretically separated in 2 % agarose gel and dyed with ethidium bromide ( cinnagen ) . bands were visualized under ultraviolet light in gel documentation ( bio - radlaboratories , hercules , ca ) . quantitative real - time reverse transcriptase polymerase chain reaction was then performed in a rotor - gene rg 3000 ( corbett research , mortlake , australia ) . the amplification procedure , run in triplicate for each sample , used sybr green premix ( takara holdings , inc , shiga , japan ) according to the manufacturer s instructions . quantitative polymerase chain reaction criteria comprised initial denaturation at 94c for 1 minute , followed by 40 amplification cycles , including denaturation at 94c for 20 seconds , annealing at 59c for 30 seconds , and extension at 72c for 30 seconds . - actin gene expression was used to normalize threshold cycle values ( ct ) of the target gene , mt - 1a , and provided us with a control for relative quantitative evaluation of the abundance of transcripts using the 2 method . we have described the immunohistochemistry procedures used in this study in detail elsewhere .18 briefly , 10 airway biopsy samples from sulfur mustard - injured patients and 10 specimens from unexposed controls were examined . all samples were fixed in 4 % formalin ( merck ) and then immersed in phosphate - buffered saline ( takara holdings , inc ) containing 30 % sucrose ( wako , osaka , japan ) . water - embedded sections 15 m thick were prepared by cryostat ( histo - line , milan , italy ) , and incubated at 4c with primary antibody at a dilution of 1:200 in phosphate - buffered saline for 12 hours . the primary antibody was a mouse monoclonal antibody raised against the human mt - 1 isoform ( abcam , cambridge , uk ) . next , the sections were incubated with biotinylated antimouse secondary antibody ( santa cruz biotechnology , santa cruz , ca ) , and diluted to 1:200 for immunostaining . the sections were visualized using the mouse abc staining system ( santa cruz biotechnology ) , and using 3,3 - diaminobenzidine as the substrate . data were calculated as mean the standard deviation of fold - changes in mt - 1a gene expression in three independent experiments . spss software ( v 15.0 ; spss , inc , chicago , il ) was used for the statistical analyses . student s t - test was used for the evaluation of differences in gene expression between the sulfur mustard - injured group and the unexposed group , and p 0.05 was considered to be statistically significant . twenty - four sufferers of chronic respiratory sequelae from exposure to sulfur mustard during the 19801988 iraniraq war were enrolled as the sulfur mustard - exposed group and 15 unexposed individuals as the control group . contact with sulfur mustard was confirmed by documents from the iranian military health services at the time of exposure . these victims all developed pulmonary symptoms immediately after contact with sulfur mustard , without any symptom - free periods . the study was approved by the ethics committee of the baqiyatallah university of medical sciences . the procedures conformed to the guiding principles of the declaration of helsinki , and all subjects signed informed consent forms for participation in the study . potential subjects having other interactive criteria , as well as those involving other chronic pulmonary diseases ( eg , asthma ) , autoimmune disease ( eg , rheumatoid arthritis ) , lung cancer , diabetes mellitus , acute infective bronchitis , or pneumonia , were excluded . drug addicts , elderly people ( 65 years old ) , smokers , organ transplant recipients , and patients with a history of occupational pulmonary exposure to other toxic agents were also excluded . age , gender , and pulmonary function test data for the two groups are shown in table 1 . all subjects were anesthetized by inhalation of 2 % aerosolized lidocaine and intravenous midazolam , and slept lightly throughout the procedure . bronchoscopy was carried out using a flexible fiberoptic bronchoscope ( bf1 t ; olympus , tokyo , japan ) passed through the airway to reach the segmental and subsegmental carinae , and endobronchial biopsy specimens were taken from these regions using bronchoscopic forceps ( olympus ) . supplemental oxygen was given throughout the procedure , and oxygen saturation was checked at regular intervals by a pulse oximeter until the subjects regained consciousness . two biopsy samples were taken from each patient , and were immediately and separately immersed in tripure isolation reagent ( roche , mannheim , germany ) and formalin ( merck , darmstadt , germany ) . the samples in tripure were stored at 80c until rna extraction , and the formalin samples were kept at 4c for immunohistochemistry . we have already described the reverse transcriptase polymerase chain reaction procedure used in this study .11 in brief , all the rna contained in the airway biopsy specimens was harvested in tripure isolation reagent in accordance with the manufacturer s protocol and kept at 80c during the procedure . the rna extracted was evaluated by nanodrop spectrophotometer ( nd - 1000 ; wilmington , de ) , and its quality was confirmed by electrophoresis in 1 % agarose gel ( cinnagen , tehran , iran ) . aliquots of 500 ng of isolated rna were utilized as templates for cdna synthesis by superscript iii reverse transcriptase ( invitrogen , carlsbad , ca ) following the manufacturer s instructions . semiquantitative reverse transcriptase polymerase chain reaction for the mt - 1a gene was carried out using equal amounts of synthesized cdna , in a final reaction volume of 25 l . all reagents and recombinant taq dna polymerase were obtained from cinnagen , and the reactions were done in a master cycler thermal cycler . specific primers for mt - 1a and - actin ( as a housekeeping gene ) were designed using primer3 software ( http://frodo.wi.mit.edu/ ) and ordered from bioneer ( daejeon , south korea , see table 2 ) . the polymerase chain reaction conditions comprised primary denaturation at 94c for 5 minutes , followed by 30 polymerase chain reaction cycles comprising denaturation at 94c for 30 seconds , annealing at 59c ( both genes at the same temperature ) for 30 seconds , extension at 72c for 60 seconds , followed by 5 minutes of terminal extension at 72c . finally , the polymerase chain reaction products were electrophoretically separated in 2 % agarose gel and dyed with ethidium bromide ( cinnagen ) . bands were visualized under ultraviolet light in gel documentation ( bio - radlaboratories , hercules , ca ) . quantitative real - time reverse transcriptase polymerase chain reaction was then performed in a rotor - gene rg 3000 ( corbett research , mortlake , australia ) . the amplification procedure , run in triplicate for each sample , used sybr green premix ( takara holdings , inc , shiga , japan ) according to the manufacturer s instructions . quantitative polymerase chain reaction criteria comprised initial denaturation at 94c for 1 minute , followed by 40 amplification cycles , including denaturation at 94c for 20 seconds , annealing at 59c for 30 seconds , and extension at 72c for 30 seconds . - actin gene expression was used to normalize threshold cycle values ( ct ) of the target gene , mt - 1a , and provided us with a control for relative quantitative evaluation of the abundance of transcripts using the 2 method . we have described the immunohistochemistry procedures used in this study in detail elsewhere .18 briefly , 10 airway biopsy samples from sulfur mustard - injured patients and 10 specimens from unexposed controls were examined . all samples were fixed in 4 % formalin ( merck ) and then immersed in phosphate - buffered saline ( takara holdings , inc ) containing 30 % sucrose ( wako , osaka , japan ) . water - embedded sections 15 m thick were prepared by cryostat ( histo - line , milan , italy ) , and incubated at 4c with primary antibody at a dilution of 1:200 in phosphate - buffered saline for 12 hours . the primary antibody was a mouse monoclonal antibody raised against the human mt - 1 isoform ( abcam , cambridge , uk ) . next , the sections were incubated with biotinylated antimouse secondary antibody ( santa cruz biotechnology , santa cruz , ca ) , and diluted to 1:200 for immunostaining . the sections were visualized using the mouse abc staining system ( santa cruz biotechnology ) , and using 3,3 - diaminobenzidine as the substrate . data were calculated as mean the standard deviation of fold - changes in mt - 1a gene expression in three independent experiments . spss software ( v 15.0 ; spss , inc , chicago , il ) was used for the statistical analyses . student s t - test was used for the evaluation of differences in gene expression between the sulfur mustard - injured group and the unexposed group , and p 0.05 was considered to be statistically significant . in total , 39 subjects participated in this study , comprising 24 sulfur mustard - injured patients and 15 normal unexposed control individuals . the average age of the sulfur mustard - injured patients and the unexposed controls was not significantly different ( 42.9 versus 43.6 years , respectively , p = 0.83 , see table 1 ) . the results of pulmonary function testing are shown in table 1 . although forced vital capacity in the control group was higher than in sulfur mustard - injured cases , the difference was not statistically significant ( p = 0.11 ) . on the other hand , forced expiratory volume in 1 second ( fev1 ) in the sulfur mustard group was significantly lower than in the controls ( p = 0.007 ) . moreover , fev1 / forced vital capacity also differed between the two groups , being significantly higher in the controls ( p = 0.001 ) . residual volume was significantly elevated in sulfur mustard - injured patients in comparison with controls ( p = 0.43 ) . we initially used a semiquantitative reverse transcriptase polymerase chain reaction to elucidate whether there were any variations in mt - 1a gene expression among the control samples , and our results revealed no significant differences ( data not shown ) . next , we examined the expression of mt - 1a in the sulfur mustard - injured patients . because the controls had expressed identical levels of the gene , all of them were used for comparison with the results in the sulfur mustard - injured group . our data revealed that mt - 1a mrna is upregulated in sulfur mustard - injured patients ( figure 1 ) . the expression of mt - 1a was also quantitatively evaluated by real - time reverse transcriptase polymerase chain reaction . the results showed that expression of this gene at the mrna level is 4.02.60 times higher in sulfur mustard - injured patients in comparison with control samples ( p = 0.001 , see table 3 ) . immunohistochemistry was employed for evaluation and localization of mt - 1 protein expression in airway biopsy samples from the two groups . it was immediately observed that the thickness of the bronchial epithelium layer in sulfur mustard - exposed patients was about twice that in normal control biopsies . in the control group , strong mt - 1 immunoreactivity was seen in airway epithelium cells , especially in the basal ( germinal ) layer ( figures 2a and 2c ) . in contrast , in sulfur mustard - injured specimens , very weak mt - 1 protein expression was seen in the bronchial epithelial cells , especially at the luminal side of the brush border cells , indicating very low mt - 1 protein expression ( figures 2b and 2d ) . bronchiolitis obliterans is the major long - term pulmonary complication in iranian victims of sulfur mustard exposure ,5 but the exact molecular mechanisms involved in the symptoms observed need to be clarified . air trapping in expiratory high - resolution computed tomography scans ( data not shown ) was the most common finding in our sulfur mustard - exposed patients . pulmonary function test results showed an airflow obstruction pattern highly indicative of bronchiolitis obliterans as the major chronic pulmonary disorder in these patients . moreover , our semiquantitative reverse transcriptase polymerase chain reaction results , confirmed by quantitative real - time reverse transcriptase polymerase chain reaction , indicate that expression of mt - 1a at the mrna level was significantly elevated in bronchial biopsy samples from the sulfur mustard - exposed group in comparison with the unexposed controls . as far as we are aware , very little is known about the precise molecular mechanisms involved in the structural modifications and pathophysiological symptoms of late complications of sulfur mustard exposure , and there are no published reports concerning mt - 1a expression and its interaction with the delayed respiratory difficulties arising from sulfur mustard exposure . a number of studies have shown that oxidative stress plays an important role in the pathogenesis of various lung diseases , including chronic obstructive pulmonary disease and asthma .2021 consistent with these findings , ghanei et al22 have hypothesized that the long - term pulmonary complications of sulfur mustard exposure are neutrophil - dominant and / or lymphocyte - dominant disorders . it has also been shown that oxidative stress due to excessive production of reactive substances and depletion of endogenous antioxidants plays an important role in the pathogenesis of these delayed pulmonary sequelae .10,23 the recent finding that sulfur mustard increases endogenous production of reactive oxygen species suggests that reactive oxygen species are likely to be involved in the toxicity induced by this chemical warfare agent .7,8 the antioxidant activity of mt - 1 was first demonstrated by thornalley and vasak ,24 and it has since been proposed that mt - 1 is involved in protection against damage caused by oxidative stress . although the exact mechanism of the free radical scavenging action of mt - 1 is not fully described , it has been postulated that mt - 1 cysteine residues can react directly as thiolate groups with a number of reactive substances , as well as with hydroxyl radicals , peroxyl radicals , superoxide hydrogen peroxide , and nitric oxide .2527 pitt et al28 demonstrated that overexpression of mt decreases the sensitivity of pulmonary endothelial cells to oxidative damage . they showed that pulmonary artery endothelial cells in sheep transfected by both human and mouse mt were more resistant to tert - butyl hydroperoxide , an oxidant - generating substance , and were also more resistant to hyperoxia . they suggested that mt can defend this cell type from attack by a variety of pro - oxidants . in another study , wesselkamper et al29 showed that mt - 1/2 transgenic mice had more resistance to nickel - induced acute lung injury than did mt - 1/2 knockout mice , implying that mt can improve survival and inhibit progression of acute lung injury . more recently , an in vivo study by helal and helal30 demonstrated that intraperitoneal administration of mt can protect rats against carmustine - provoked lung injury because of its antioxidant attributes and its ability to suppress tumor necrosis factor alpha . upregulation of mt - 1a mrna in the airways of sulfur mustard - injured patients , in addition to oxidative stress , could be due to inflammation . some in vivo experiments have demonstrated that a number of pro - inflammatory cytokines , as well as tumor necrosis factor alpha , interleukin ( il ) - 1 , il - 6 , and interferon gamma can induce mt gene expression .3133 depending on the site , stimulus direction , and type of pathophysiologic situation , mt can have diverse anti - inflammatory roles .34 emad and emad35 evaluated levels of several cytokines in bronchoalveolar lavage fluid from sulfur mustard - exposed patients and demonstrated that il - 8 , il - 1 , il - 6 , il - 12 , and tumor necrosis factor alpha levels in sulfur mustard - injured patients were all significantly higher than in controls , and suggested that neutrophilic pulmonary inflammation is possibly the mechanism underlying the long - term pulmonary complications of sulfur mustard exposure . molecular level investigation of the existence of inflammation in the airways of sulfur mustard - injured patients is underway in our laboratory , and preliminary , as yet unpublished data show that tumor necrosis factor alpha expression at the mrna level is significantly upregulated in sulfur mustard - exposed patients in comparison with controls , suggesting that inflammatory processes are involved in this chronic pulmonary complication . consistent with these findings , takano et al36 have shown that mt - 1/2 knockout mice are more vulnerable to acute pulmonary inflammatory injury mediated by intratracheal instillation of lipopolysaccharide than wild - type mice . additionally , in line with these findings , a complementary dna microarray study based on acute inflammatory murine lung damage induced by lipopolysaccharide and diesel exhaust particles revealed that mt - 1 gene expression at the mrna level is significantly upregulated in mice exposed to these irritants .17 similarly , a more recent study showed that mt plays an important role in ozone - induced pulmonary inflammation , and showed that lung inflammation is significantly greater in mt - 1/2 knockout than wild - type mice .37 however , despite numerous investigations of the possible contribution of mt - 1 to inflammatory lung injuries , its exact role still needs to be elucidated . paradoxically , our immunohistochemistry results revealed that , in contrast with the upregulation of mt - 1a mrna expression in airway biopsy samples from sulfur mustard - injured patients , its protein level was higher in control subjects . several mt - 1 immunoreactive cells were seen in the bronchial epithelia of our control cases , and immunoreactivity was more intense in cells adjacent to the basement membrane . this finding is in accordance with that of courtade et al ,38 who evaluated the expression of mt in the normal human lung , and observed positively stained pleural endothelial cells and basal cells from the bronchial epithelium . in contrast , in our chemically - injured cases , only a very weak expression of mt - 1 was observed on the luminal side of the bronchial epithelium . we have also already shown an inconsistency between mrna and protein expression of lipocalin - 2 and heme oxygenase in the bronchial epithelium of sulfur mustard - exposed patients compared with unexposed cases .11,39,40 we hypothesize that this discrepancy between mrna and protein expression of mt - 1a may be caused by translational inefficiency and / or posttranslational regulation . interestingly , it has been revealed that , despite a huge amount of evidence strongly suggesting that the expression of mt genes is transcriptionally regulated , new data have also indicated that posttranslational modulations also have effects on mt gene expression .14 this discrepancy may be due to a change in the expression of micrornas , which are posttranscriptional regulators that bind to complementary sequences on target messenger rna transcripts , usually resulting in translational repression and gene silencing .41 intriguingly , it has been shown that administration of n - acetylcysteine can significantly improve clinical symptoms in sulfur mustard - exposed patients ,19 and it has also been demonstrated that n - acetylcysteine , as an antioxidant , provides thiol groups which are essential for serum glutathione production .39 in this way , n - acetylcysteine can compensate for decreased expression of mt - 1 protein , but , in spite of this improvement , no cure has as yet been achieved in sulfur mustard - injured patients . this study shows that although the expression of mt - 1 at the mrna level was significantly increased in the bronchial epithelium of sulfur mustard - exposed patients , expression of mt - 1 protein was significantly higher in the airways of our controls . this upregulation of mt - 1 mrna seems to be due to oxidative stress and depletion of the endogenous antioxidants which exist in the lungs of patients who have inhaled sulfur mustard , and may reflect an attempt to ameliorate this harmful situation by reestablishment of homeostasis . the contrasting depletion of its protein may be a result of secondary effects of sulfur mustard toxicity . therefore , further studies clarifying the mechanisms involved in the long - term outcome of sulfur mustard exposure are warranted .\noutput:\n" }, { "from": "agent", "value": "background : sulfur mustard can cause several long - term complications in the organs of individuals exposed to this toxic gas , and among these , pulmonary sequelae are the most important . more than 25 years after the iran iraq war , thousands of iranians are suffering from the chronic respiratory complications of sulfur mustard . currently , based on several clinical findings , bronchiolitis obliterans is confirmed as the major diagnosis in these patients . numerous studies have revealed that this disorder is strongly associated with oxidative stress due to excessive production of harmful reactive substances and decreased levels of endogenous antioxidants . metallothioneins ( mts ) are a group of low molecular weight sulfhydryl - rich intra - cellular proteins , and several isoforms have been identified in humans . mt - 1a is an inducible and important mt isoform , which is transcriptionally activated by a variety of stress stimuli , such as free radicals.methods : mt - 1 mrna expression and protein levels in endobronchial biopsy samples from 24 sulfur mustard - exposed patients and 15 unexposed control cases were evaluated by semi - quantitative reverse transcriptase polymerase chain reaction , real - time reverse transcriptase polymerase chain reaction , and immunohistochemistry.results : mrna - mt - 1a expression levels in sulfur mustard - exposed patients were upregulated compared with normal samples . protein expression was also markedly higher in controls than in sulfur mustard - exposed patients.conclusion : upregulation of mt - 1a mrna in patients who have been exposed to sulfur mustard seems to be due to oxidative stress , which is induced in an attempt to ameliorate this harmful situation by reestablishment of homeostasis , but depletion of its protein might be due to secondary consequences of sulfur mustard toxicity , which are as yet not understood ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the manhattan institute analysis attributes differences in life expectancy between states to new drugs while failing to control for infant mortality , the single most important determinant of life expectancy . because life expectancy is calculated as an average , death rates in younger age groups have the greatest impact . in the 19th century , when infant deaths were common , life expectancy in 1900 was only 49.24 years . plunging infant mortality rates ( imrs ) increased life expectancy to 68.07 years in 1950 and 75.37 years in 1990.10 between 1990 and 2004 , life expectancy increased to 77.9 years .11 disparities in imrs could account for most differences in longevity in lichtenberg s analysis ( see fig . 1 ) . today , the average imr in the u.s . is 7.1 per 1000 births , but rates range from a low of 4.9 in new hampshire to a high of 13.5 in the district of columbia .10 centers for disease control data show that imrs ranged from 5.07.2 in the ten states noted by lichtenberg to have the longest life expectancy . the ten states with the shortest life expectancy had imrs ranging from 7.1 to 10.4.12 infant mortality affects life expectancy at birth but not at age 65 , which is consistent with the far greater differences reported for life expectancy at birth than at age 65 in the lichtenberg report . figure 1the relationship between infant mortality rates and life expectancy at birth in the united states . life expectancy at birth is based on the table us states ranked by life expectancy in lichtenberg , f. 2007the role of medical innovation and other factors .9 arizona and washington , dc were not included in the cited table and are excluded here as well . data on infant mortality rates were obtained from the national center for health statistics , cdc . deaths , age - adjusted death rates , and life expectancy at birth , by race and sex ; and infant mortality rates , by race : united states , final 2003 and preliminary 2004.11 table 1estimated effects of changes in drug vintage * or population characteristics change in life expectancychange in productivitychange in expendituresfrom birthfrom age 65drughome health carenursing homehospitalphysiciantotal1 - y increase medicaid drug vintage0 .16 y0 .09 y1 .1 % 3.5 % 9.0 % 2.0 % ns4 .0 % ns1 - y increase medicare drug vintage0 .03 y0 .01 yns0 .3 % ns0 .5 % 0.3 % nsns0 .1 unit increase in education index ** nsnsns1 .6 % 2.6 % 0.6 % 0.6 % 1.6 % 1.1 % 10 percentage point increase in number of people with health insurance coveragensns1 .4 % ns21 .9 % 5.7 % 2.3 % 10.6 % 4.2 % 10 % increase in income0 .16 y0 .09 y6 .5 % ns7 .1 % 6.4 % 4.7 % 4.8 % 2.7 % source : lichtenberg , f. 2007the role of medical innovation and other factors9the table is based on table 7 , which shows regression results using the fixed - weight medicaid drug vintage index9 * vintage is defined as the year that the active ingredients in prescription drugs were first approved by the fda * * in lichtenberg s analysis , education index is an index of mean educational attainment of residents of state i in year tns denotes non - significant at the p 0.05 level the relationship between infant mortality rates and life expectancy at birth in the united states . = 0.58 . life expectancy at birth is based on the table us states ranked by life expectancy in lichtenberg , f. 2007the role of medical innovation and other factors .9 arizona and washington , dc were not included in the cited table and are excluded here as well . data on infant mortality rates were obtained from the national center for health statistics , cdc . deaths , age - adjusted death rates , and life expectancy at birth , by race and sex ; and infant mortality rates , by race : united states , final 2003 and preliminary 2004.11 estimated effects of changes in drug vintage * or population characteristics source : lichtenberg , f. 2007the role of medical innovation and other factors9 the table is based on table 7 , which shows regression results using the fixed - weight medicaid drug vintage index9 * vintage is defined as the year that the active ingredients in prescription drugs were first approved by the fda * * in lichtenberg s analysis , education index is an index of mean educational attainment of residents of state i in year tthe manhattan institute study adjusted for aids , obesity , and smoking an unusual set of variables . however , aids is not among the 15 leading causes of death in any state in the u.s . obesity and smoking are risk factors for numerous diseases , but are not acceptable surrogate markers for causes of death . ethnicity , education , income , and other sociodemographic factors are associated with differences in life expectancy . in 2003 , there was a gap of 5.3 years between blacks and whites in life expectancy at birth , primarily due to differences in death rates from homicide , heart disease , and hiv .14 in 2000 , a 25 - year - old with a high school degree or less could expect to live another 50 years , while someone who had attended college could expect to live almost another 57 years .15 differences in sociodemographic factors across states could thus contribute to differences in longevity . the measure of drug age in the manhattan institute report is the average year in which the active ingredients in prescription drugs were first approved by the food and drug administration ( fda ) . drug vintage , can not accurately assess the rate of adoption of new drugs because two - thirds of what are consideredonly a third of new drug approvals involve novel drugs , also called new molecular entities .16 under lichtenberg s scheme , threea new formulation of a drug approved in 1980 would be 1980 vintage . and a new combination of a drug approved in 1980 with a second drug approved in 2000 would be categorized as a 1990 vintage . the fact that two - thirds of new drugs would be classified as older drugs confounds any conclusions about new drugs . grouping drugs by age rather than effect is odd ; a new acne drug is unlikely to affect lifespan . it would have made more sense to limit this analysis to drugs that affect mortality . reverse causation is not effectively controlled for in the analysis , and could explain several key findings . rather than new drugs extending lives , older people may use newer drugs . yet , lichtenberg s analysis does not control for age . during the years covered by lichtenberg s analyses ( which pre - date medicare part d ) , drugs paid for by medicare were newer than drugs paid for by medicaid in every state as revealed in table 5 of lichtenberg s paper .9 the gap between the mean age of medicare and medicaid - covered drugs within some states was as high as eight years more than twice the difference in age observed across states for medicare or medicaid covered drugs . this suggests that medicare recipients , primarily adults over age 65 , used newer drugs more often than younger adults who received drugs only through medicaid , which covers poor people . state - to - state variation in the use of specific drugs could also affect the manhattan institute s findings . for example , hydrocodone / acetaminophen preparations were two of the ten best - selling drugs between 2002 and 2006.17 these are old drugs : acetaminophen was first approved by the fda in 1951 ; hydrocodone , an opiate , was first used in cough syrups in the 1930s . differences in hydrocodone / acetaminophen usage among states could have a substantial impact on the indices . a 10 % increase in use of hydrocodone / acetaminophen could lower a state s medicaid vintage by 0.1 year a very large decline given the limited variation across states . opiates are often used in the treatment of cancer and chronic pain . rather than shortening lives , older drugsmay simply be more commonly used by people with life - shortening illnesses another example of reverse causation . lichtenberg s analyses linked increased productivity with the use of new drugs , but found no association with education . increased incomes , however , were associated with shorter lives ( see table 1 ) . although health insurance coverage was not found to be associated with longevity , coverage was associated with increased productivity and decreased health care expenditures . contrary to a large body of literature correlating longer lives with higher incomes and socioeconomic status ,13,1821 lichtenberg s regressions also show a strong negative correlation between per capita income and life expectancy both at birth and at age 65 ( see table 1 ) . lichtenberg concludes that rising income between 1991 and 2004 reduced life expectancy at birth by almost a year ( 0.86 years ) and life expectancy at age 65 by six months ( 0.49 years ) . lichtenberg cites several papers to support his finding that higher income lowers life expectancy , but the cited papers actually focused on cyclical changes in income . within a country , higher income that is associated with more people working or more people working longer hoursdoes lead to transiently higher death rates .22,23 however , these studies examined how changes in death rates respond to departures from the normal trend in growth of income , and do not claim to show that life expectancies decline as countries become wealthier . lichtenberg s analysis may have confused the cyclical , short - term income effects that are highly correlated with specific years with the impact of a long - term trend increase in income . changes in life expectancy would be more highly correlated with long - term income growth . the impact of rising income was most likely captured by the year variables ( coefficients of which were not included . ) including year variables in a regression will likely pick up much of the increase in life expectancy associated with a rising income trend and could lead to the erroneous conclusion that increased income shortens lives . the conclusion that new drugs enhance growth in productivity ( measured as output per worker per year ) is based on medicaid data ; medicare data showed no correlation . the regression that addresses productivity and categories of health care spending indicates that a one - year increase in drug vintage raises productivity by 1.1 % ( see table 1 , column 3 ) . extrapolated over the 13 - year period of lichtenberg s analysis , the results imply that newer drugs accounted for a 12.5 percentage point increase in productivity , or nearly half of total productivity growth ( 27.0 % , based on a 50.3 % increased output24 and an 18.3 % increase in the number of employed persons the denominator in lichtenberg s productivity term ) .25 this result is implausible . other implausible results include lichtenberg s findings that education was unrelated to productivity , and that health insurance reduces health care expenditures while increasing productivity . the positive association between education and productivity is as strong as an association can be .26 lichtenberg s findings that health insurance coverage had a marginally significant positive relationship with productivity imply that a 10 - percentage point increase in health insurance coverage is associated with a 1.4 % rise in productivity . given current levels of gross domestic product , this would imply that a 10 % increase in coverage would increase output by almost $ 200 billion annually . this result is absurd , because it implies that relatively small increases in health insurance coverage lead to huge jumps in economic output . the highly significant association between health insurance coverage and reduced health care expenditures ( see table 1 ) implies that a 10 - percentage point increase in health insurance coverage could reduce total health care spending 4.2 % . at current levels of health care spending , this implies that expanding health insurance coverage by 10 % would save the country more than $ 80 billion a year . to the contrary , research shows that health care expenses increase with expanded insurance coverage .2729 a peculiar relationship between drug spending and medicare drug vintages calls into question the ability of these indices to reflect new drug use . while the medicaid drug vintages show , predictably , that increased use of new drugs is associated with higher drug spending , the medicare results associate increased use of new drugs with reduced drug spending . a review of lichtenberg s regressions ( table 1 ) shows that a one - year increase in medicare drug vintage is associated with a 0.3 % decline in per capita drug spending . although it seems implausible that more rapid adoption of new drugs would reduce drug expenditures , this anomaly is not addressed in the text . the report in question purports to support the concept that new drugs save lives . however , the analysis fails to control for differences among states in infant mortality rates , demographics , or causes of death . inadequate surrogate measures of health status are used , and reverse causation could explain several key findings . in economic analyses , a statistical regression stands or falls in its entirety . a regression that passes inspection for internal validityshould be tested for its ability to withstand manipulation ; for example , removing a variable , splitting a time period , or running the regression in two halves should not qualitatively change the results of a robust regression . lack of internal consistency indicates that there is something wrong . in the lichtenberg analysis , the negative relationship between income and life expectancy , the finding that health insurance coverage lowers costs while increasing productivity , and the lack of a relationship between education and productivity are all anomalous results inconsistent with a large body of previous research . previous studies by lichtenberg have also been criticized .46 two previous studies , using medical expenditure panel survey ( meps ) data , concluded that replacing older drugs with newer drugs would save money . the first study30 was criticized for a cross - sectional design inappropriate for determining cause and effect .4 additionally , the use of prescriptions as a unit of analysis rather than people meant that the death of a person using ten drugs would have been counted as ten deaths .5 the second study ( nber ) failed to control for prior health status and other variables .4 an independent reanalysis , using the same data and methodologies in conjunction with more accurate drug approval dates and the consideration of plausible alternative assumptions , could not confirm lichtenberg s conclusions .4 an analysis of cardiovascular drugs that used the same meps data set found no association between the use of newer drugs and non - drug expenditures after controlling for the number of drugs or the mix of drugs of different ages .6 lichtenberg s claims that adopting new drugs saves money , increases life expectancy , and increases productivity are unreliable and should not be considered in health policy decisions . moreover , while some new drugs are therapeutic advances , others are not . for example , the federally - funded allhat study found that chlorthiazide , an older , inexpensive diuretic , was superior to new drugs for treating hypertension .30 the catie study , also government - funded , found that older antipsychotics are as effective as newer ones for treating schizophrenia .33,34 also , newer drugs may amplify risks rather than benefits . novel drugs carry more risks than older drugs because problems associated with long - term use or in special populations ( for example , the elderly ) are revealed only after a drug is in widespread use .35 half of drug withdrawals or black box warnings occur within two years of approval .36 the lichtenberg study argues that there have been very large returns from the development of new drugs in the form of longer life expectancy and in the form of reduced non - drug health care costs and increased productivity . the implication is that the current model of drug development and financing is extremely successful and that altering it , for example through the bulk purchases of drugs in the medicare prescription drug benefit , could seriously undermine the further development of new drugs . our critique shows that lichtenberg s methods are seriously flawed and his conclusions are therefore unsupportable . in the absence of more compelling research on the impact of newer drugsprescription drugs are the most rapidly growing component of health care costs and will impose a major burden on government budgets and the economy as a whole if they are not reined in .\noutput:\n" }, { "from": "agent", "value": "a recent study published by the manhattan institute why has longevity increased more in some states than in others ? the role of medical innovation and other factors , purported to show that the more rapid adoption of new drugs has substantial benefits in the form of increased life expectancy , higher productivity and lower non - drug health care expenditures . this study has been cited as evidence supporting the more rapid acceptance of new drugs in medicaid , medicare , and other public programs and has helped to shape public debate on the value of new drugs . this analysis questions the key conclusions of the study . it points out that the key statistical regressions appear to be misspecified , since they show anomalies such as a negative correlation between income growth and life expectancy and find no relationship between education and productivity growth . methodological flaws addressed include lack of adjustment for infant mortality rates ; inadequate proxy measures of health status ; lack of adjustment for ages of individuals and other sociodemographic factors ; inherent problems with the definition of drug age , or vintage ; and the failure to consider reverse causation as an obvious explanation for several findings . the manhattan institute study does not provide reliable evidence for favoring adoption of newer drugs in either public or private health care programs ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: esophageal cancer is the third most common cancer in india constituting 67 % of all newly diagnosed cancers . though currently , surgical excision is the primary modality of treatment , but it is not always applicable because 80 % patients present in an advanced stage or comorbid conditions or because of patient 's unwillingness or lack of surgical expertise . radical external radiation alone results in a dismal 5 - year survival rate of 6 % , with more than 80 % failing locally only . still , the 3 - year survival hover around 1720 % only . because of the impressive 3 - year survival results ( 2730 % ) , concomitant chemoradiation is now considered as the standard approach for the treatment of unresectable carcinoma esophagus . despite these improved results , the locoregional control of the disease is poor , and about 48 % patients fail locally . the key to further improvement in the treatment results therefore appears to lie in increasing the biological response with the optimal use of combined modality treatment , namely , radiation only or chemoradiation followed by intraluminal brachytherapy ( ilbt ) . ilbt , due to its rapid dose fall - off and ability to deliver a high dose to the intraluminal disease , is used for local boost . because of the shorter treatment time , better patient compliance , and ease of administration , high - dose - rate ( hdr ) brachytherapy is preferred . but the dose fractionation and dose per fraction in hdr brachytherapy of carcinoma esophagus has been a matter of concern because of the high incidence of adverse events with certain dose schedules . this retrospective study has been done with a premise to analyze the different radiation schedules with ilbt in patients with unresectable carcinoma esophagus in terms of dysphagia - free survival ( dyfs ) , local control ( lc ) , disease - free survival ( dfs ) , and complications . this is a retrospective study of patients of esophageal carcinoma treated between january 2005 and june 2010 . patients were considered eligible for the study if they had squamous cell carcinomas of thoracic esophagus , without distant metastasis , a karnofsky performance score ( kps ) more than 70 , a tumor length less than 10 cm , and undergone external beam radiation therapy with or without concurrent chemoradiation , followed by ilbt [ figure 1 ] . out of the total 1580 patients of esophageal carcinomas registered in the institution , 86 patients ( 5.4 % ) were selected who could satisfy the above - mentioned criteria . initially at our institution , patients were treated with external beam radiation therapy alone ( schedule a ) , with no chemotherapy , followed by 23 weeks of hdr brachytherapy . the total biological equivalent dose ( bed ) of this schedule was 98.22 gy3 , where gy3 stands for the dose related to late toxicities to normal tissues with an / ratio of 3 . later on to improve the results of lc , the ebrt dose was increased from 35 gy / 15 # to 44 gy / 22 # , and concurrent weekly chemotherapy was added . both these schedules , schedule b ( 6 gy2 ) and schedule c ( 4.68 gy3 ) were designed to be equivalent for late effects using the linear quadratic model and the bed for both these schedules was 109.33 gy3 . n = 51 - represents rt f / b ilbt 6 gy in 2 sessions , n = 21 - represents crt f / b ilbt 6 gy in 2 sessions , n = 14 - represents crt f / b ilbt 4.68 gy in 3 sessions all patients included in the analysis underwent initial evaluation with a barium swallow and endoscopy with biopsy to assess the mucosal extent of the disease and a cect scan to assess the extraesophageal and nodal spread . the patient and tumor characteristics have been shown in table 1 . patient and tumor characteristics all patients were planned on a simulator ct and following a barium swallow , fields were set so as to cover the tumor adequately with a margin of 5 cm proximally and distally and 23 cm laterally . all patients were treated on theratron 780 c or 6 mv linac . for schedules b and c , the concurrent chemotherapy consisted of weekly cycles of cisplatin 30 mg / m in infusion with adequate hydration and a 5 - fluorouracil 325 mg / m iv bolus . weekly hemogram and renal function tests were checked prior to chemotherapy . on the completion of chemoradiation , 23 weeks were allowed for the resolution of acute radiation reactions . patients were given injection pentazocine 30 mg / m iv and injection hyoscine butyl bromide 2040 mg / m iv as premedication . endoscopy was done by the gastroenterologists with a flexible fiberoptic endoscope ( olympus gif 160 ) . the parameters evaluated included the extent of the tumor , presence of ulcer , and stricture . a pagliero rowland type selectron bougie , 100 cm long and with 1 cm external diameter , was then threaded over a guidewire and positioned so that the lower end was 2 cm beyond the lower end of the initial lesion . the dose was prescribed at 1 cm from the central axis of the source as per american brachytherapy society consensus guidelines . patients were treated using a remote afterloading machine ( microselectron ) using an ir source with a maximum activity of 10 ci . patients were clinically evaluated for dysphagia at 1 , 2 , 3 , 6 , and 12 months . endoscopy was done at 3 months for disease assessment and biopsy was done when indicated . cect of the chest and abdomen was obtained if any clinical suspicion of either local recurrence or metastasis was there . toxicities were graded as per the rtog / eortc criteria , and the toxicities analyzed are shown in table 2 . the median follow - up period was 12.1 months . a complete response was defined as a complete disappearance of the endoscopically visible disease and the absence of malignant cells on biopsy , and a partial response as a reduction in tumor mass by more than 50 % without new areas of tumor development . a minimal response was defined as a reduction of less than 50 % in the size of the tumor while progressive disease as an increase in the size by more than 25 % or appearance of new lesions . statistical analysis was performed using the statistical package for social sciences ( spss ) software , version 16.0 . all p - values were two sided , and a p - value of 0.05 was taken as significant . this is a retrospective study of patients of esophageal carcinoma treated between january 2005 and june 2010 . patients were considered eligible for the study if they had squamous cell carcinomas of thoracic esophagus , without distant metastasis , a karnofsky performance score ( kps ) more than 70 , a tumor length less than 10 cm , and undergone external beam radiation therapy with or without concurrent chemoradiation , followed by ilbt [ figure 1 ] . out of the total 1580 patients of esophageal carcinomas registered in the institution , 86 patients ( 5.4 % ) were selected who could satisfy the above - mentioned criteria . initially at our institution , patients were treated with external beam radiation therapy alone ( schedule a ) , with no chemotherapy , followed by 23 weeks of hdr brachytherapy . the total biological equivalent dose ( bed ) of this schedule was 98.22 gy3 , where gy3 stands for the dose related to late toxicities to normal tissues with an / ratio of 3 . later on to improve the results of lc , the ebrt dose was increased from 35 gy / 15 # to 44 gy / 22 # , and concurrent weekly chemotherapy was added . both these schedules , schedule b ( 6 gy2 ) and schedule c ( 4.68 gy3 ) were designed to be equivalent for late effects using the linear quadratic model and the bed for both these schedules was 109.33 gy3 . patients were retrospectively analyzed . figure 2 shows the distribution of the patients across the three radiation schedules . n = 51 - represents rt f / b ilbt 6 gy in 2 sessions , n = 21 - represents crt f / b ilbt 6 gy in 2 sessions , n = 14 - represents crt f / b ilbt 4.68 gy in 3 sessions all patients included in the analysis underwent initial evaluation with a barium swallow and endoscopy with biopsy to assess the mucosal extent of the disease and a cect scan to assess the extraesophageal and nodal spread . the patient and tumor characteristics have been shown in table 1 . all patients were planned on a simulator ct and following a barium swallow , fields were set so as to cover the tumor adequately with a margin of 5 cm proximally and distally and 23 cm laterally . all patients were treated on theratron 780 c or 6 mv linac . for schedules b and c , the concurrent chemotherapy consisted of weekly cycles of cisplatin 30 mg / m in infusion with adequate hydration and a 5 - fluorouracil 325 mg / m iv bolus . weekly hemogram and renal function tests were checked prior to chemotherapy . on the completion of chemoradiation , 23 weeks were allowed for the resolution of acute radiation reactions . patients were given injection pentazocine 30 mg / m iv and injection hyoscine butyl bromide 2040 mg / m iv as premedication . endoscopy was done by the gastroenterologists with a flexible fiberoptic endoscope ( olympus gif 160 ) . the parameters evaluated included the extent of the tumor , presence of ulcer , and stricture . a pagliero rowland type selectron bougie , 100 cm long and with 1 cm external diameter , was then threaded over a guidewire and positioned so that the lower end was 2 cm beyond the lower end of the initial lesion . the dose was prescribed at 1 cm from the central axis of the source as per american brachytherapy society consensus guidelines . patients were treated using a remote afterloading machine ( microselectron ) using an ir source with a maximum activity of 10 ci . patients were clinically evaluated for dysphagia at 1 , 2 , 3 , 6 , and 12 months . endoscopy was done at 3 months for disease assessment and biopsy was done when indicated . cect of the chest and abdomen was obtained if any clinical suspicion of either local recurrence or metastasis was there . toxicities were graded as per the rtog / eortc criteria , and the toxicities analyzed are shown in table 2 . a complete response was defined as a complete disappearance of the endoscopically visible disease and the absence of malignant cells on biopsy , and a partial response as a reduction in tumor mass by more than 50 % without new areas of tumor development . a minimal response was defined as a reduction of less than 50 % in the size of the tumor while progressive disease as an increase in the size by more than 25 % or appearance of new lesions . statistical analysis was performed using the statistical package for social sciences ( spss ) software , version 16.0 . all p - values were two sided , and a p - value of 0.05 was taken as significant . the treatment was well tolerated and all patients completed the course of treatment prescribed . none of the patients had required a treatment gap during the course of external radiation . there were no significant differences in the incidence of acute toxicities across the three radiation schedules . in treatment toxicities as shown in table 2 , four patients , two each in schedules a and b , had required gaps between the ilbt sessions due to the presence of deep ulcers . this gap was required after the first session in both patients . in both these patients , figure 3 shows the prevalence of dysphagia in the three radiation schedules across the follow - up period . the maximum incidence of dysphagia was seen at 1 month with all the three radiation schedules , the highest being 95 % , seen among those treated with the radiation only schedule , i.e. , schedule a. the incidence of dysphagia at 1 month was 90 % and 80 % for schedules b and c , respectively . the absence of dysphagia was noted in 40 % , 50 % , and 55 % patients in the three schedules , respectively , analyzed for outcomes post - treatment in the sixth month . however , the incidence of patients with dysphagia increased again at 12 months , and the increase was maximally seen among schedule a ( 77 % ) , followed by schedule b ( 72 % ) . only 55 % patients treated with schedule c had dysphagia at 12 months . the temporal profile of patients with dysphagia after treatment completion . schedule a represents rt f / b ilbt 6 gy in 2 sessions , schedule b represents crt f / b ilbt 6 gy in 2 sessions , schedule c represents crt f / b ilbt 4.68 gy in 3 sessions all patients had a partial response locally after external radiation . following ilbt , the radiological responsefigure 4 shows that there was no significant difference in the partial response rates in the three radiation schedules . the complete response rate was 39 % in schedule a , 40 % in schedule b and 44 % in schedule c ( p = 0.6 ) . radiological response post - ilbt at 1 month figure 5 and table 3 show that the median dyfs is the highest , 12.1 months , in schedule c , while for schedules a and b ( higher dose per fraction ) it is low , i.e. , 5.1 and 7.0 months , respectively . the 2 - year actuarial dyfs is again insignificantly higher for schedule c as compared to schedules a and b ( p = 0.168 ) . schedule a - rt f / b ilbt 6 gy / 2 # . schedule b - crt f / b ilbt 6 gy / 2 # , schedule c - crt f / b ilbt 4.68 gy / 3 # median and 2 - year dysphagia - free survival as shown in figure 6 and table 4 , the 2 - year lc rates were the worst with radiation alone schedules , i.e. , 67.6 % after a median follow - up of 12.1 months , while with chemoradiation schedules , it was approaching 88 % . schedule a - rt f / b ilbt 6 gy / 2 # . schedule b - crt f / b ilbt 6 gy / 2 # , schedule c - crt f / b ilbt 4.68 gy / 3 # figure 7 and table 5 show that the 2 - year dfs was again insignificantly higher for chemoradiation schedules , while for the radiation only schedule , i.e. , schedule a , it is low ( only 46 % ) . schedule a - rt f / b ilbt 6 gy / 2 # . schedule b - crt f / b ilbt 6 gy / 2 # , schedule c - crt f / b ilbt 4.68 gy / 3 # disease free survival rates figure 8 shows that the stricture formation was the commonest complication observed within all the three radiation schedules , but it was the highest , seen in 45 % ( 20/51 ) patients treated with radiation only schedule a , and 21 % ( 5/21 ) in schedule b , i.e. , higher dose per fraction of brachytherapy . ulceration was seen in two patients each in schedules a and b. tracheoesophageal fistula developed in total five patients , two each in both chemoradiation schedules and one in the radiation only schedule . hemorrhage was seen in one patient in schedule b. there was no complication in 71 % patients ( 10/14 ) treated with schedule c. figure 9 shows the pattern of failure at the time of the last follow - up . local recurrence was seen in 30 patients out of 51 in schedule a , while it was seen in 4 of 21 and 2 of 14 patients in schedules b and c , respectively . a total of 13 patients died of brain metastasis among 86 patients , and 11 among these were treated with schedule a. seven patients developed lung metastasis . a total of 7 patients among 81 developed metastasis at sites other than brain and lung . external radiation alone without chemotherapy followed by ilbt in esophagus has been considered to be associated with lower lcs and dfs in various studies . to improve upon the results , few studies have been done on ilbt following chemoradiation , and have reported differing toxicities and clinical benefits . based on these studies , the american brachytherapy society had given consensus guidelines on the use of ilbt . they had suggested a dose / fractionation of 10 gy by hdr brachytherapy given in two sessions of 5 gy each 1 week apart . clinical data from patients treated at our institute using two sessions of 6 gy each had shown good lc , with acceptable toxicities . hence , the radiation only schedule ( with higher dose per fraction of external radiation ) has been compared with two biologically equivalent chemoradiation schedules ( one with a lower dose per fraction and the other with a higher dose per fraction of brachytherapy boost ) to analyze the three schedules in terms of dyfs , lc , dfs , and toxicities . thirty - five patients treated with chemoradiation completed the scheduled course with at least three cycles of chemotherapy followed by ilbt . though grade i and ii hematological toxicity , renal toxicity , and vomiting were seen , no grade iii toxicity was noted . western studies however quote a poorer compliance to treatment of 6470 % only , with grade iii and iv toxicities noted in 3058 % patients , probably due to the higher doses of external radiation and chemotherapy used in these studies . dysphagia scores were initially high in all the schedules , which steadily decreased and plateaued off . however , grade ii and iii dysphagia appeared to increase in the sixth month in schedules a and b. although not statistically significant because of the small patient number , this might be reflective of the slightly higher rate of stricture formation in both schedules a and b due to the higher dose per fraction of external radiation and higher dose per fraction of brachytherapy boost , respectively . schedule c shows a trend toward slightly better symptom control , which is supported by the evidence of a significant increase in the number of patients without dysphagia in the post - treatment period at 1 month and also the highest median dyfs of 12.1 months . schedules b and c showed a trend toward better lc , 87.5 % and 88.9 % versus 67.6 % in the radiation group , respectively ( p value , not significant ) , but major complications like ulceration and tracheoesophageal fistulas were seen more commonly in schedule b using higher dose per fraction of brachytherapy boost . these results are similar to other published studies , which used higher doses of external radiation and chemotherapy . in the rtog 92 - 07 trial , in which patients were given 50 gy external radiation , followed 2 weeks later by ilbt 2 sessions of 5 gy each and chemotherapy on weeks 1 , 5 , 8 , and 11 , the lc rate was 73 % . however , there was a high incidence of severe complications ( 58 % ) , including 12 % treatment - related esophageal fistula , based on which , an extreme caution in employing ilbt boost following chemoradiation was urged . a study by calais et al . , in which 60 gy conventional external radiation was given concurrent with cisplatin , 5 - flourouracil , and mitomycin followed by two sessions of ilbt 5 gy each , reported lc rates of 74 % at 1 year . this indicates that chemoradiation schedules with brachytherapy boost are feasible but require a careful selection of patients with a good kps , along with a need of further studies to standardize hdr ilbt schedules with chemoradiation protocols . in patients with unresectable carcinoma esophagus , concurrent chemoradiation followed by an ilbt boost is feasible with an acceptable toxicity profile and good lc rates . however , an increased risk of complications is seen with the higher dose per fraction of brachytherapy ( 6 gy2 # ) . so wherever suitable , we should try to add chemotherapy concurrent with radiation and boost it with ilbt . still there is a need for the standardization of hdr ilbt schedules with chemoradiation protocols .\noutput:\n" }, { "from": "agent", "value": "aim : the aim was to analyze different radiation schedules with high - dose - rate ( hdr ) brachytherapy in patients with unresectable carcinoma esophagus in terms of dysphagia - free survival ( dyfs ) , local control ( lc ) , disease - free survival ( dfs ) , and complications.materials and methods : eighty - six patients were studied under three different radiation schedules : schedule a radiation 35 gy / 15 # followed by hdr brachytherapy 6 gy each in two sessions ; schedule b chemoradiation 35 gy / 15 # with weekly injection cisplatin 30 mg / m2 infusion and 5 - fluorouracil 325 mg / m2 bolus followed by hdr brachytherapy 6 gy each in two sessions ; and schedule c same chemoradiation dose followed by hdr brachytherapy three sessions of 4.68 gy each . the median follow - up was 12.1 months.results : treatment compliance was good . there were no significant differences in the incidence of acute toxicities across the three schedules . no grade iii toxicities were noted . at 1 month , 27 patients had dysphagia improvement , which was not different across the three schedules . at 6 months , schedule c showed a trend toward better symptom control of dysphagia ( dysphagia free = 55 % ) . the 2 - year dyfs reached 49.5 % in schedule c. two - year lc rates were approximating 89 % in both chemoradiation schedules versus 67.6 % in schedule a. the 2 - year dfs was also high in chemoradiation schedules . major complications like ulceration and tracheoesophageal fistulas were more often seen with schedule b with a higher dose per fraction of the brachytherapy schedule.conclusion : in unresectable carcinoma esophagus , radiation - only schedules are associated with lower lc and dfs rates . concurrent chemoradiation followed by a brachytherapy boost is feasible in suitable patients with a good karnofsky performance score and are associated with higher dyfs , lc , and dfs with acceptable toxicities . still there is a need for the standardization of hdr brachytherapy schedules with chemoradiation protocols ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: even relatively small cartilage lesions frequently induce pain and disability for the patient . without repaircommonly advocated repair techniques for these smaller lesions are microfracture , autologous chondrocyte implantation ( aci ) , and autologous osteochondral transplantation ( aot ) . compared with aci , the advantage of aot is that it is a one - stage procedure and mature hyaline cartilage is present in the defect site directly after transplantation . in literatureboth very positive reports and concerns have been presented for aot in the knee . concerns are related to donor site morbidity , to survival of the transplanted cartilage , and to the reported negative outcome in some patient series . particularly mal - indications , treatment of too large defects , the use of too large plugs or co - morbidity within the knee could all negatively influence the clinical outcome of aot . adequate positioning , together with intrinsic stability of the transplanted plugs are likely to be important prerequisites to reach clinical success . both are important for adequate osseous integration of the transplanted plug in the subchondral bone and for survival of the hyaline cartilage . in addition , osteochondral transplants should be placed flush with the joint surface , since leaving the plugs proud generates stresses at the edges leading to early damage to the graft . subsidence of plugs , on the other hand , leads to stresses at the rim of the host cartilage , with similar damage there . earlier biomechanical studies on an aot cadaver model , using the oats system , reported on relatively high forces needed to displacebottomed plugs beyond flush level as compared to plugs placed with a gap between the cylinder graft and the bottom of the recipient subchondral bone defect ( unbottomed plugs ) . from this biomechanical study , well - seated ( bottomed ) osteochondral plugs thus seemed less susceptible for subsidence . the aim of this goat study was to compare bottomed versus unbottomed osteochondral transplants in vivo . it was hypothesized that bottomed plugs would indeed be superior in maintaining their flush level and by that would lead to a better gross morphology of the reconstruction and to a better survival of hyaline cartilage of both donor and host cartilage at a follow - up period of 6 weeks . prior to surgery , each goat had been randomly assigned to receive two bottomed or unbottomed plugs . centrally , in the weight - bearing area of the medial femoral condyle , a standardized oval defect ( length 12 mm , width 6 mm ) of 3 mm depth was created in an ap orientation with the use of a customized drill guide , a circular drill of 6 mm diameter and a small sharp osteotome ( recipient site ) ( fig . in accordance with clinical practice , a cylindrical osteochondral transplantation was performed to restore the articular defect using a 6 mm diameter osteochondral autograft transfer system ( oats ; arthrex , st .1 a standardized 3 - mm - deep oval defect on the medial femoral condyle ( length 12 mm , width 6 mm ) . b final result of a two - plug osteochondral transplantation on the medial femoral condyle a standardized 3 - mm - deep oval defect on the medial femoral condyle ( length 12 mm , width 6 mm ) . b final result of a two - plug osteochondral transplantation on the medial femoral condyle two donor osteochondral plugs were harvested from the lateral trochlea of the goat knee , which is in accordance with the situation in patients . care was taken to harvest plugs as much perpendicular to the articular surface as possible without penetrating the lateral wall of the trochlear groove . the harvested donor plugs were adjusted to an exact length of 8 mm , measured with a precision slide calliper , by removal of some deep trabecular bone by a surgical bone nibbling plier . depending on the assigned treatment , a recipient hole with an 8 or 10 mm depth was created in the femoral condyle defect for a bottomed or unbottomed situation , respectively . the bottom of the recipient hole was softly tampered , with the provided steel rod , to flatten it in order to ensure an exact matching depth and direct contact of the transplanted plug on the bottom of the recipient hole in case of a bottomed transplantation . subsequently , the available donor osteochondral plug was gently tampered into place until flush level with the adjacent articular cartilage was obtained . after the first plug was in place , the entire procedure was repeated for the second transplant ( fig . plugs were seated exactly on the flattened bottom , and in the unbottomed situation , the plugs were floating 2 mm above the flattened bottom . the trochlear donor site defects were either left empty in six goats or were filled with impacted remainders of the available subchondral bone derived from preparing the recipient holes , leaving small , but shallow defects ( 12 goats ) . in six of these 12 goats , the remaining shallow defects were completely filled up to a flush level with a commercially available hemostatic collagen type i sponge ( spongostan ; ferrosan a / s , soeborg , denmark ) . it was hypothesized that partly restoring the donor defect with the available impacted subchondral bone would lead to a better healing of these defects as compared to empty defects . in addition , filling the remaining defect with a collagen type i sponge would then possibly further enhance the healing process of the donor defect . directly after surgery , the goats were placed in a hammock for 7 days . the first 3 days the goats received standard injections of flunixine ( 1 mg / kg ) ( finadyne ; schering - plough animal health , oss , the netherlands ) and buprenorphine ( 0.018 ml / kg ) ( temgesic ; msd animal health , oss , the netherlands ) as analgesic . antibiotic prophylaxis consisted of ampicillin subcutaneously administered for 5 days postoperatively ( 7.5 ml / day ) ( albupen ; intervet , boxmeer , the netherlands ) . after 7 days , the goats were transported in the hammock to an outdoor farm where they were allowed to move freely and unrestricted . after 2 weeks , tetracycline ( 25 mg / kg ) was administered , after 4 weeks calcein green ( 25 mg / kg ) and finally after 6 weeks , 2 days before killing , alizarin red ( 30 mg / kg ) . after 6 weeks , the goats were killed with an overdose of pentobarbital ( nembutal , ceva sant animale , maassluis , the netherlands ) and the knee joint was completely dissected from femur en tibia . all investigations were conducted in conformity with ethical principles of research and all protocols were approved by the institutional animal ethics committee ( ru - dec2007 - 106 ) . directly after harvesting , the knee joint was opened and photographs of the recipient and donor sites were taken . the photographs of the reconstructions were evaluated by three blinded observers ( nk , gh , and pb ) and scored for gross morphological appearance of the surface congruency of individual plugs ( table 1 ) . subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered to be negative signs . the separate scores of each of both transplanted plugs were added , resulting in a maximum score of 4 per goat.table 1macroscopic scoring systemcharacteristicsscoreclinical acceptable or flush virtually no negative signs2clinical suboptimal minor negative signs1clinical failure obvious negative signs0subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered as negative signs macroscopic scoring system subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered as negative signs the operated condyle was dissected with a diamond - coated and water - cooled sawing blade ( blade thickness 300 m ) exactly in two halves in the ap direction through the center of the two plugs and photographs were taken again . thereafter , two slices were made from each section plane of both halves of the defect and processed for histology . the two slices were used for vitality testing with cell tracker green cmfda ( 5 - chloromethylfluorescein diacetate ; molecular probes , invitrogen ltd , uk ) and propidium iodide ( molecular probes , invitrogen ltd . , uk ) . directly following coloring , the specimens were photographed through a fluorescence photomicroscope ( zeiss axioplan 2 ; carl zeiss bv , sliedrecht , the netherlands ) and frozen afterward . in a later stage , they were defrosted and vital cells were colored by nadh - diaphorase ( sigma - aldrich chemie bv , zwijndrecht , the netherlands ) with nitroblue - tetrazolium ( nbt ; sigma - aldrich chemie bv , zwijndrecht , the netherlands ) . after taking photographs , these slices were further processed for routine histology as described below . all specimens were fixated in a 4 % buffered formalin solution ( ph 7.4 ) for at least 1 day . the specimens were embedded in polymethylmethacrylate and sectioned ( 7 - m - thick sections ) with a microtome ( leica rm 2155 , leica microsystems nederland bv , rijswijk , the netherlands ) , and stained with hematoxylin and eosin , alcian blue and safranin o. serial sections of the trochlear donor defect were prepared in the transverse direction . the reconstructions were graded for graft level with surrounding cartilage , graft cartilage thickness , cartilage integration , degenerative changes at cartilage edges , changes in tidemarks at cartilage edges , integration of adjacent subchondral bone , and subchondral cavity formation ( table 2 ) . this scoring system was adapted from similar scales for osteochondral cartilage repair published by other researchers . the same three blinded observers ( nk , gh , and pb ) scored two specimens from the center of the repaired defect independent of each other . in each reconstruction ,3 locations were evaluated , the anterior host plug contact area ( a ) , the central plugplug contact area ( b ) , and the posterior plug host contact area ( c ) . the scores for each location were summed to obtain a total score for each reconstruction.table 2histological scoring systemcharacteristicsscoregraft level with surrounding cartilage level450 % of graft cartilage thicknessraised250 % of graft cartilage thickness below150 % of graft cartilage thicknessraised0graft cartilage thickness 75100 % of adjacent cartilage25075 % 150 % 0cartilage integration bonding through cartilage like tissue3 fissure fully filled with fibrous tissue2 fissure partially filled with fibrous tissue1 empty fissure0degenerative changes at cartilage edges normal cellularity , no clusters , normal staining3 mild hypocellularity , some clusters , moderate staining2 moderate hypocellularity , slight staining1 severe hypocellularity , poor or no staining0changes in tidemarks at cartilage edges both normal2 one damaged or abnormal1 both damaged or abnormal0integration of adjacent subchondral bone fully osseous integration4 fully integrated with partial fibrous tissue3 fully integrated only fibrous tissue2 partially integrated1 no integration0subchondral cavity formation no cavities3 small cavities1 large cavity0total maximum score per location21 in each reconstruction , 3 locations were evaluated , the anterior host plug contact area ( a ) , the central plugthe scores for each location were summed to obtain a total score for each reconstruction histological scoring system in each reconstruction , 3 locations were evaluated , the anterior host plug contact area ( a ) , the central plugthe scores for each location were summed to obtain a total score for each reconstruction datasets from gross morphological scoring and histological grading were evaluated nonparametrically , as normal distribution could not be assumed for all parameters . directly after harvesting , the knee joint was opened and photographs of the recipient and donor sites were taken . the photographs of the reconstructions were evaluated by three blinded observers ( nk , gh , and pb ) and scored for gross morphological appearance of the surface congruency of individual plugs ( table 1 ) . subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered to be negative signs . the separate scores of each of both transplanted plugs were added , resulting in a maximum score of 4 per goat.table 1macroscopic scoring systemcharacteristicsscoreclinical acceptable or flush virtually no negative signs2clinical suboptimal minor negative signs1clinical failure obvious negative signs0subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered as negative signs macroscopic scoring system subsidence , protrusion , tilting , sclerosis , and fibrous overgrowth were considered as negative signsthe operated condyle was dissected with a diamond - coated and water - cooled sawing blade ( blade thickness 300 m ) exactly in two halves in the ap direction through the center of the two plugs and photographs were taken again . thereafter , two slices were made from each section plane of both halves of the defect and processed for histology . the two slices were used for vitality testing with cell tracker green cmfda ( 5 - chloromethylfluorescein diacetate ; molecular probes , invitrogen ltd , uk ) and propidium iodide ( molecular probes , invitrogen ltd . , uk ) . directly following coloring , the specimens were photographed through a fluorescence photomicroscope ( zeiss axioplan 2 ; carl zeiss bv , sliedrecht , the netherlands ) and frozen afterward . in a later stage , they were defrosted and vital cells were colored by nadh - diaphorase ( sigma - aldrich chemie bv , zwijndrecht , the netherlands ) with nitroblue - tetrazolium ( nbt ; sigma - aldrich chemie bv , zwijndrecht , the netherlands ) . after taking photographs , these slices were further processed for routine histology as described below . all specimens were fixated in a 4 % buffered formalin solution ( ph 7.4 ) for at least 1 day . the specimens were embedded in polymethylmethacrylate and sectioned ( 7 - m - thick sections ) with a microtome ( leica rm 2155 , leica microsystems nederland bv , rijswijk , the netherlands ) , and stained with hematoxylin and eosin , alcian blue and safranin o. serial sections of the trochlear donor defect were prepared in the transverse direction . the reconstructions were graded for graft level with surrounding cartilage , graft cartilage thickness , cartilage integration , degenerative changes at cartilage edges , changes in tidemarks at cartilage edges , integration of adjacent subchondral bone , and subchondral cavity formation ( table 2 ) . this scoring system was adapted from similar scales for osteochondral cartilage repair published by other researchers . the same three blinded observers ( nk , gh , and pb ) scored two specimens from the center of the repaired defect independent of each other . in each reconstruction ,3 locations were evaluated , the anterior host plug contact area ( a ) , the central plugplug contact area ( b ) , and the posterior plug host contact area ( c ) . the scores for each location were summed to obtain a total score for each reconstruction.table 2histological scoring systemcharacteristicsscoregraft level with surrounding cartilage level450 % of graft cartilage thicknessbelow150 % of graft cartilage thickness raised0graft cartilage thickness 75100 % of adjacent cartilage25075 % 150 % 0cartilage integration bonding through cartilage like tissue3 fissure fully filled with fibrous tissue2 fissure partially filled with fibrous tissue1 empty fissure0degenerative changes at cartilage edges normal cellularity , no clusters , normal staining3 mild hypocellularity , some clusters , moderate staining2 moderate hypocellularity , slight staining1 severe hypocellularity , poor or no staining0changes in tidemarks at cartilage edges both normal2 one damaged or abnormal1 both damaged or abnormal0integration of adjacent subchondral bone fully osseous integration4 fully integrated with partial fibrous tissue3 fully integrated only fibrous tissue2 partially integrated1 no integration0subchondral cavity formation no cavities3 small cavities1 large cavity0total maximum score per location21 in each reconstruction , 3 locations were evaluated , the anterior host plug contact area ( a ) , the central plug plug contact area ( b ) , and the posterior plugthe scores for each location were summed to obtain a total score for each reconstruction histological scoring system in each reconstruction , 3 locations were evaluated , the anterior host plug contact area ( a ) , the central plugplug contact area ( b ) , and the posterior plug host contact area ( c ) . datasets from gross morphological scoring and histological grading were evaluated nonparametrically , as normal distribution could not be assumed for all parameters . the gross morphological scoring showed a significantly higher score for surface congruency in bottomed plugs as compared to unbottomed reconstructions ( p = 0.04 ) ( table 3 ) . table 3macroscopic scoresbottomed ( n = 9 ) unbottomed ( n = 9 ) p valueanterior plug1 .50.40.80.70.03 posterior plug1 .20.70.70.8 n.s.total2 .70.81.50.40.04 values are mean sdn.s . = p 0.05 no differences between local and total histological grading scores for bottomed and unbottomed plugs were found ( table 4 ) . table 4microscopic scoresbottomed ( n = 9 ) unbottomed ( n = 9 ) p valuea11 .13.612.33.0 n.s.b8 .83.09.73.3 n.s.c12 .32.511.33.7 n.s.total32 .06.032.18.5 n.s.values are mean sd . ( a ) anterior host plug contact area , ( b ) the central plug plug contact area , and ( c ) the posterior plug ( a ) anterior host plug contact area , ( b ) the central plugplug contact area , and ( c ) the posterior plug host contact area both the nadh - diaphorase staining and the life dead assay showed a similar distribution of vital and necrotic cells ( fig . 2 ) . necrotic chondrocytes were present in equal low numbers in both host and plug articular cartilage . only at the edges toward the interface between plugs , there was a thin acellular zone of cartilage ( fig . clustered chondrocytes were present in almost all plugs and bordering host cartilage ( fig .2 a , b , d ) . occasionally , larger gaps were also present ( figs . 2c , 3b ) . the cartilage interface between plugs was in most cases very thin and plugs seemed to be press - fit ( fig . no integration of cartilage in between plugs or between plugs and host cartilage was found.fig .2 histology of sections stained with nadh - diaphorase with nbt ( nitroblue - tetrazolium ) for vitality ( a , b , c ) and section ( d ) in which living cells are stained with cell tracker green . notice difference in thickness between host ( h ) and plug ( p ) cartilage . in b3routine histology staining of thin sections with safranin o ( a , b ) and haematoxylin and eosin ( c , d ) . a , c bottomed plugs , b , d unbottomed plugs . a notice cartilage - like tissue formation in the gap between the two inserted plugs ( p ) . in ba larger nonfilled gap is present between host ( h ) and plug ( p ) cartilage . d new bone formation in subchondral bone of transplanted plug histology of sections stained with nadh - diaphorase with nbt ( nitroblue - tetrazolium ) for vitality ( a , b , c ) and section ( d ) in which living cells are stained with cell tracker green . notice difference in thickness between host ( h ) and plug ( p ) cartilage . in ba , b bottomed reconstructions , c , d unbottomed reconstructions routine histology staining of thin sections with safranin o ( a , b ) and haematoxylin and eosin ( c , d ) . a , c bottomed plugs , b , d unbottomed plugs . a notice cartilage - like tissue formation in the gap between the two inserted plugs ( p ) . in ba larger nonfilled gap is present between host ( h ) and plug ( p ) cartilage . d new bone formation in subchondral bone of transplanted plug the tidemarks were generally intact ( fig . particularly , if the subchondral bone was revascularized , small capillaries of the newly formed fibrous subchondral tissue were penetrating the tidemark , and by that , the integrity of the tidemark was reduced ( fig . bv is a blood vessel penetrating to the tidemark subchondral bone of host ( a ) , and of unbottomed plug . bv is a blood vessel penetrating to the tidemark the central part of the subchondral bone of the transplanted plugs was still mainly avascular and necrotic with empty osteocyte lacunae and necrotic medullary tissue . from the deeper parts of the defect and from the interfaces with the host bone , this process was characterized by abundant osteoclastic resorption sites of the transplanted bone ( fig .3 c ) , new bone formation on the remnants of the bone of the plugs and bone remodeling .3 d ) ; however , irrespective of the treatment group , in various locations in the subchondral areas , small areas of enchondral bone formation were present . irrespective to the treatment modality , all donor sites showed rather similar histological appearances . in the defects , the surface of the newly formed tissue was either slightly depressed under the original contour of the defect or in a few cases it was elevated above the original contour ( fig . in only two defects that were filled with the hemostatic collagen type i sponge , centrally a few remnants of the original graft material could be found ( fig . , it was surrounded by some mononuclear lymphocytic cells but without a clear immunological reaction . in all defects that were filled with bone graft , thisthe edges of the donor site showed in all cases some form of depletion of the matrix , decreased chondrocyte vitality and clustering of chondrocytes ( fig . 5d ) . fig .5 a , b haematoxylin and eosin - stained sections showing representative micrographs of donor site . a empty defect . d edge of host cartilage ( hc ) with clustered chondrocytes ( arrows ) a , b haematoxylin and eosin - stained sections showing representative micrographs of donor site . a empty defect . the gross morphological scoring showed a significantly higher score for surface congruency in bottomed plugs as compared to unbottomed reconstructions ( p = 0.04 ) ( table 3 ) . table 3macroscopic scoresbottomed ( n = 9 ) unbottomed ( n = 9 ) p valueanterior plug1 .50.40.80.70.03 posterior plug1 .20.70.70.8 n.s.total2 .70.81.50.40.04 values are mean sdn.s . no differences between local and total histological grading scores for bottomed and unbottomed plugs were found ( table 4 ) . table 4microscopic scoresbottomed ( n = 9 ) unbottomed ( n = 9 ) p valuea11 .13.612.33.0 n.s.b8 .83.09.73.3 n.s.c12 .32.511.33.7 n.s.total32 .06.032.18.5 n.s.values are mean sd . ( a ) anterior host plug contact area , ( b ) the central plug ( a ) anterior host plug contact area , ( b ) the central plugboth the nadh - diaphorase staining and the life dead assay showed a similar distribution of vital and necrotic cells ( fig . 2 ) . necrotic chondrocytes were present in equal low numbers in both host and plug articular cartilage . only at the edges toward the interface between plugs , there was a thin acellular zone of cartilage ( fig . clustered chondrocytes were present in almost all plugs and bordering host cartilage ( fig . occasionally , larger gaps were also present ( figs . 2c , 3b ) . the cartilage interface between plugs was in most cases very thin and plugs seemed to be press - fit ( fig . no integration of cartilage in between plugs or between plugs and host cartilage was found.fig .2 histology of sections stained with nadh - diaphorase with nbt ( nitroblue - tetrazolium ) for vitality ( a , b , c ) and section ( d ) in which living cells are stained with cell tracker green . notice difference in thickness between host ( h ) and plug ( p ) cartilage . in b3routine histology staining of thin sections with safranin o ( a , b ) and haematoxylin and eosin ( c , d ) . a , c bottomed plugs , b , d unbottomed plugs . a notice cartilage - like tissue formation in the gap between the two inserted plugs ( p ) . in b a larger nonfilled gap is present between host ( h ) and plug ( p ) cartilage . d new bone formation in subchondral bone of transplanted plug histology of sections stained with nadh - diaphorase with nbt ( nitroblue - tetrazolium ) for vitality ( a , b , c ) and section ( d ) in which living cells are stained with cell tracker green . notice difference in thickness between host ( h ) and plug ( p ) cartilage . in ba , b bottomed reconstructions , c , d unbottomed reconstructions routine histology staining of thin sections with safranin o ( a , b ) and haematoxylin and eosin ( c , d ) . a , c bottomed plugs , b , d unbottomed plugs . a notice cartilage - like tissue formation in the gap between the two inserted plugs ( p ) . in ba larger nonfilled gap is present between host ( h ) and plug ( p ) cartilage . particularly , if the subchondral bone was revascularized , small capillaries of the newly formed fibrous subchondral tissue were penetrating the tidemark , and by that , the integrity of the tidemark was reduced ( fig . bv is a blood vessel penetrating to the tidemark subchondral bone of host ( a ) , and of unbottomed plug . the central part of the subchondral bone of the transplanted plugs was still mainly avascular and necrotic with empty osteocyte lacunae and necrotic medullary tissue . from the deeper parts of the defect and from the interfaces with the host bone , a process of creeping substitution of the necrotic bone was present . this process was characterized by abundant osteoclastic resorption sites of the transplanted bone ( fig .3 c ) , new bone formation on the remnants of the bone of the plugs and bone remodeling .3 d ) ; however , irrespective of the treatment group , in various locations in the subchondral areas , small areas of enchondral bone formation were present . irrespective to the treatment modality , all donor sites showed rather similar histological appearances . in the defects , the surface of the newly formed tissue was either slightly depressed under the original contour of the defect or in a few cases it was elevated above the original contour ( fig .5 b ) , without clear correlation with the filling material in the defect . in only two defects that were filled with the hemostatic collagen type i sponge , centrally a few remnants of the original graft material could be found ( fig . , it was surrounded by some mononuclear lymphocytic cells but without a clear immunological reaction . in all defects that were filled with bone graft , thisthe edges of the donor site showed in all cases some form of depletion of the matrix , decreased chondrocyte vitality and clustering of chondrocytes ( fig . 5d ) . fig .5 a , b haematoxylin and eosin - stained sections showing representative micrographs of donor site . a empty defect . d edge of host cartilage ( hc ) with clustered chondrocytes ( arrows ) a , b haematoxylin and eosin - stained sections showing representative micrographs of donor site . a empty defect . the most important finding of the present study was that chondrocyte vitality was maintained after osteochondral transplantation . on gross appearance , bottomed plugs seemed to reveal lesser subsidence tendency than unbottomed plugs ; however , on histological evaluation , no significant differences could be detected between groups . in addition , the repair tendency of the donor defects was not improved by the two different filling techniques evaluated in this animal model . gross morphological scoring showed that the bottomed plugs performed superior in maintaining flush level with the surrounding subchondral bone . the fact that on histological scoring bottomed and unbottomed plugs failed to reveal a significant difference may be induced by the scoring method itself . the histological scoring was performed in the mid - sagittal plane only , whereas for macroscopic evaluation , the entire contour of the transplantation was judged and not just the appearance of the mid - sagittal plane ( see also fig . 6 for further explanation ) . irrespective the fact that histological scoring was performed on the midsagittal plane only , it has to be recognized that no major differences were encountered between bottomed and unbottomed plugs . clearly the extent of subsidence was relatively low in this animal model , which may be related to the compact subchondral bone structure of goats . irrespective of the absence of a significant difference between the two groups , the evaluated different aspects of the histological score are still important parameters for the long - term success of the aot technique . the most important long - term success aspect of the aot technique above the aci techniques or microfracture is the instantaneous restoration of the defect site with mature healthy hyaline cartilage , which was indeed confirmed in our study by an excellent chondrocyte vitality after transplantation.fig .6 schematics for illustrating the possible discrepancy in judging the ( flush ) level of a whole graft through microscopic sections of the specimen . the dotted lines indicate the outer boundaries of the two thick sections , which were made . notice the less than optimal perpendicularity of the plug s cartilage surface in respect to its subchondral bone in this schematic representation . c represents the lateral view of the theoretical sections made at the dotted lines in b. 1 notice the subsidence below flush level of the posterior ( right ) plug .3 notice the protrusion above flush level of the posterior ( right ) plug schematics for illustrating the possible discrepancy in judging the ( flush ) level of a whole graft through microscopic sections of the specimen . the dotted lines indicate the outer boundaries of the two thick sections , which were made . notice the less than optimal perpendicularity of the plug s cartilage surface in respect to its subchondral bone in this schematic representation . c represents the lateral view of the theoretical sections made at the dotted lines in b. 1 notice the subsidence below flush level of the posterior ( right ) plug .3 notice the protrusion above flush level of the posterior ( right ) plug chondrocyte survival also appears to be dependent on the harvesting procedure of the osteochondral graft , where sharper cutting devices reduce the thickness of the layer of dead chondrocytes . moreover , harvesting by hand is superior above power trephine harvesting . in this study , only small margins of the plugs were acellular , indicating that indeed also limited chondrocyte death took place during the harvest . besides the harvesting procedure , tampering the plugs into the bone might also induce chondrocyte death at the surface of the plugs . the fact that in both groups the surface layer was populated with vital cells indicated that the tempering probably did not induce a necrosis of the superficial chondrocytes . this indicates that the clinically used forces to insert plugs are most likely within the margin to induce cartilage damage , especially since goat cartilage is thinner and thereby more prone to damage , and higher tempering force is needed in the more compact goat bone , compared with human bone . the potential for donor site morbidity is still a major drawback of the aot technique and is held responsible for inferior results in some studies . for that reason , we evaluated some simple attempts to enhance the healing potential of these defects . however , filling the donor site defects with impacted cancellous bone , with or without a collagen type i layer , did not induce any new subchondral bone restoration as compared to empty defects . although in the deeper parts of the defects some new bone was formed , there was no relation with the graft material . . however , the results and recommendations from this study for patients should be carefully interpreted within the limitations of the model . bone of healthy animals is of good quality and because of high loads more compact than in humans , which may have resulted in a more tightly press - fit placement of the plugs and thus a relative resistance to subsidence tendency . this phenomenon may have played a role in the encountered absence of a significant difference between bottomed andfurthermore , it has to be recognized that in this study an osteochondral transplantation using the oats system was evaluated , which system on theoretical grounds may offer less intrinsic stability to the transplanted plugs than the alternatively available mosaicplasty system . in contrast to the oats system , in the mosaicplasty system , primary stability of the transplants is not only dependent on the standard shear forces between plug and host bone , but also on the conically shaped bottom part of the defect created by means of a dilator . the recommendation to bottom osteochondral plugs may thus mainly apply to the currently evaluated oats system . subsidence of the transplanted plugs may be detrimental for the eventual clinical outcome and should be avoided . in this animal model , using the oats system , macroscopic scoring revealed less subsidence tendency when the transplanted plugs were bottomed . in spite of the fact that the encountered benefit of bottomingwas only limited in this animal model , bottoming is still recommended for clinical practice , especially when the oats system is used . larger comparative clinical trials will be necessary to truly elucidate the potential clinical benefit of bottoming .\noutput:\n" }, { "from": "agent", "value": "purposethe aim of this study was to evaluate subsidence tendency , surface congruency , chondrocyte survival and plug incorporation after osteochondral transplantation in an animal model . the potential benefit of precise seating of the transplanted osteochondral plug on the recipient subchondral host bone ( bottoming ) on these parameters was assessed in particular.methodsin 18 goats , two osteochondral autografts were harvested from the trochlea of the ipsilateral knee joint and inserted press - fit in a standardized articular cartilage defect in the medial femoral condyle . in half of the goats , the transplanted plugs were matched exactly to the depth of the recipient hole ( bottomed plugs ; n = 9 ) , whereas in the other half of the goats , a gap of 2 mm was left between the plugs and the recipient bottom ( unbottomed plugs ; n = 9 ) . after 6 weeks , all transplants were evaluated on gross morphology , subsidence , histology , and chondrocyte vitality.resultsthe macroscopic morphology scored significantly higher for surface congruency in bottomed plugs as compared to unbottomed reconstructions ( p = 0.04 ) . however , no differences in histological subsidence scoring between bottomed and unbottomed plugs were found . the transplanted articular cartilage of both bottomed and unbottomed plugs was vital . only at the edges some matrix destaining , chondrocyte death and cluster formation was observed . at the subchondral bone level , active remodeling occurred , whereas integration at the cartilaginous surface of the osteochondral plugs failed to occur . subchondral cysts were found in both groups.conclusionsin this animal model , subsidence tendency was significantly lower after bottomed versus unbottomed osteochondral transplants on gross appearance , whereas for histological scoring no significant differences were encountered . since the clinical outcome may be negatively influenced by subsidence , the use of bottomed grafts is recommended for osteochondral transplantation in patients ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: 13 there are a few different tips in patients with this clinical state that are considered in part due to the anatomical malposition of the heart . 2 , 3 usually , these cases go for an on - pump technique and there are very few cases of off - pump coronary artery bypass grafting with mid - term follow - up .47 in this case report , an old woman with dextrocardia undergoing coronary revascularization is presented . a 64 - year - old woman was admitted to a university hospital due to exertional chest pain with a functional class of ii to iii . dextrocardia was suspected on physical examination , and it was corroborated by chest x - ray ( figure 1 ) . she underwent selective coronary angiography , which documented dextrocardia , morphologic left main coronary artery disease with 90 % narrowing , and morphologic left anterior descending artery disease with 70 % narrowing . after installing the basic invasive and non - invasive monitoring devices , including left radial arterial cannulation for invasive arterial blood pressure line , twelve - lead electrocardiography , and pulse oximetry , anesthesia was induced after administering 500 ml of ringer s solution over 15 minutes . thereafter , a combination of sufentanil ( 0.7 mcg / kg ) , midazolam ( 0.05 mg / kg ) , and atracurium ( 0.5 mg / kg ) was used for the induction of anesthesia and tracheal intubation . afterwards , the central venous line was introduced through the left internal jugular vein in concordance with underlying dextrocardia ; however , the patient had a large skin nevus on the left side of the neck and , as a result , a right central venous catheter was inserted . for the maintenance of anesthesia , 1 to 1.5 % isofluranewas administered combined with an intravenous infusion of 100 mcg sufentanil , 150 mg atracurium , and 10 mg midazolam to keep the level of anesthesia depth between 40 to 60 according to the bispectral index monitoring . after median sternotomy and longitudinal pericardiotomy , the surgical process was continued by harvesting the right internal mammary artery ( rima ) and a piece of the greater saphenous vein from the left leg . the rima was then anastomosed to the morphologic left anterior descending artery ( lad ) . also , two saphenous vein grafts were anastomosed to the diagonal and obtuse marginal branches . during the course of anesthesiaalso , a combination of esmolol , intravenous nitrates , amiodarone , and other cardio - active drugs was used to keep the hemodynamic status stable and calm . proximal anastomosis was done while the systolic blood pressure was kept constant between 85 to 90 mmhg . the operation was done with the surgeon being positioned on the left side of the patient . after the termination of the surgery , the patient was transferred to the cardiac intensive care unit uneventfully while mechanically ventilated and monitored for hemodynamic parameters . inside the intensive care unit , the patient was fully awake after five hours from entry to the ward ; she was extubated shortly afterwards . there was no major complication overnight , and the patient was transferred to the ward the day after surgery . she was discharged from the hospital on the fifth postoperative day ( figure 2 ) . on multi - slice ct angiography , performed two years later , all of the grafts were patent and perfect ( figure 3 ) . dextrocardia , a congenital anomaly , is not clinically common .13 in adult cases , it is a rare condition to see dextrocardia accompanied by atherosclerotic coronary disease needing surgical intervention because these cases usually do not have enough life span to present with atherosclerotic coronary artery disease processes , due to co - existing anomalies .25 the incidence of dextrocardia associated with situs inversus totalis is 1 to 10,000 , and these patients usually continue their lives until they develope ischemic heart disease , which requires surgery .68 there are a number of differences in the management of the coronary revascularization procedure in these patients , and these differences are usually related to the anatomic malposition of the heart . usually , central venous catheters are placed through the left side in such patients to have a straight course to the anatomically lefthowever , in this case , a right central venous catheter was inserted because of the presence of a large skin nevus on the left side of the neck . in this patient , myocardial revascularization was performed by harvesting the rima and anastomosing it to the morphologic lad . also , two pieces of the saphenous venous graft were anastomosed to the diagonal and obtuse marginal branches . the surgical technique was in many aspects the same as that for off - pump coronary artery bypass grafting for levocardia , although for a right - handed surgeon it would be much easier to stand on the left side of the patient . of course , this is not always the rule and the surgeon may stand on the right or the left side of the patient , according to his or her easiness . to our knowledge , this is the first case report of off - pump coronary artery bypass grafting in a patient with dextrocardia and severe coronary artery disease with excellent mid - term follow - up .\noutput:\n" }, { "from": "agent", "value": "coronary revascularization in patients with dextrocardia is not a common clinical condition . there are very few cases of off - pump coronary artery bypass . a 64 - year - old woman was admitted to a university hospital due to exertional chest pain . her primary diagnosis was coronary artery disease superimposed on dextrocardia , which was first suspected on physical examination , with the patient having right - sided heart sounds on auscultation . it was corroborated by chest x - ray . after diagnostic evaluations , including coronary angiography , she underwent off - pump coronary artery bypass grafting due to a significant left main coronary artery stenosis associated with dextrocardia . two years later , multi - slice ct angiography revealed patent grafts , demonstrating good clinical results ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the disease anisakiasis was first recognized by van thiel in 1960.1 it is caused by an infestation of the third - stage larvae of anisakis simplex . a. simplex is distributed worldwide and is frequently found in a large variety of fish consumed by humans . eating uncooked fish or seafood containingthe resulting disease , known as anisakiasis or anisakidosis , is due mainly to two mechanisms : allergic reaction and direct tissue damage . the former ranges from isolated urticaria and angioedema to life - threatening anaphylactic shock associated with gastrointestinal symptoms ( gastroallergic anisakiasis ) . allergic reactions can occur after primary infection , solely through the presence of anisakis allergens in food .1,2 tissue damage is due to invasion of the gut wall and development of eosinophilic granuloma , ulcer , or perforation .2,3 cases of gastric anisakiasis ( 95 % ) are more common than those of enteric anisakiasis , and the latter is rarely reported .4 anisakis larvae can be seen directly by esophagogastroduodenoscopy or colonoscopy and can be removed with biopsy forceps . only one similar report exists in which an anisakis larva was found with a duodenal ulcer , but it was not reported in detail .3 herein , we report a case of a 47 - year - old man who had duodenal anisakiasis with a duodenal ulcer . a 47 - year - old otherwise healthy man visited our hospital with a complaint of sharp epigastric pain lasting 2 days . the patient did not have h. pylori and had no abnormal findings on an esophagogastroduodenoscopy ( egd ) conducted 6 months previously . additionally , he had no recent travel history and no significant medical history ; however , the patient had eaten a raw flatfish 3 days before admission . he had increased bowel sounds and direct tenderness in the epigastric area but did not have abdominal distention or a palpable mass . laboratory tests revealed normal biochemical and hematologic blood indexes , except for an elevated white blood cell count of 15,500 / mm with a normal eosinophil count and c - reactive protein level of 3.63 mg / dl . on admission , egd revealed a round to oval active duodenal ulcer , about 10 mm in diameter , with a sharp margin and marginal elevation at the duodenal bulb . at 5 mm away from the ulcer margin , a whitish linear worm was found with half of its body penetrating the duodenal mucosa ( fig .2 ) . additionally , a rapid urease test showed a negative result . a proton pump inhibitor ( pantoprazole 40 mg , 1 tablet qd ) was administered to treat the duodenal ulcer . the patient 's symptoms rapidly improved after removal of the duodenal anisakis , and the patient was discharged on the third day after egd . the follow - up egd after 4 weeks of treatment for the duodenal ulcer revealed complete healing at the ulcer site without anisakis ( fig . anisakiasis , which was first reported by van thiel in 1960,1 is caused by the third - stage larvae of anisakis species , mainly a. simplex , and to a much lesser extent a. physeteris , after the ingestion of raw or undercooked fish or seafood . the adult anisakis lives in the stomach of marine mammals such as whales and dolphins . humans are only accidental hosts .2 anisakiasis is classified as either the luminal or the invasive form , according to the presence of bowel wall invasion by anisakis larvae .2 the luminal form does not cause major clinical symptoms , but the invasive form can . the invasive form is subdivided into gastric and intestinal types , according to the penetration site . cases of gastric anisakiasis ( 95 % ) are more common than are those of enteric anisakiasis , and the latter is rarely reported .2,3 anisakiasis is caused by two main mechanisms : allergic reactions and direct tissue damage . the former ranges from isolated urticaria and angioedema to life - threatening anaphylactic shock associated with gastrointestinal symptoms . allergic reactions can occur after the primary infection of anisakis with exposure to allergens in the food . direct tissue damage is due to parasite invasion of the gut wall , development of eosinophilic granuloma , or perforation .4 sudden abdominal pain occurs within 12 to 72 hours after the ingestion of raw fish in cases of acute gastric anisakiasis . in these instances , the larvae can be seen directly by egd and can be removed with biopsy forceps . chronic anisakiasis of the stomach may mimic a peptic ulcer , chronic gastritis , or gastric cancer . there are occasional reports of gastric anisakiasis with a morphology that resembles the borrmann type 2 advanced gastric cancer or a type iia + iii early gastric cancer .5 there are also a few reports of the endoscopic discovery of a worm in the base of a gastric ulcer .6 patients with enteric anisakiasis have diffuse and colicky abdominal pain within several days after ingesting raw fish . it has been reported that anisakiasis is usually a self - limiting disease cured by conservative management for 1 to 2 weeks after the onset of symptoms . a positive result on a serological testhas been shown to be helpful when diagnosing ; however , positive ige values against anisakis in subjects without symptoms of allergy can not be considered a reliable indicator . this antibody has been detected in 25 % of healthy controls and lacks specificity because of cross - reactivity with other parasite antigens . additionally , it is not generally available and is therefore of limited benefit in early diagnosis .7 increased eosinophil levels are observed in less than half of the patients with anisakiasis , and when the eosinophil levels are increased , they tend to be normal on the first hospital day and gradually rise later .4,7 this case showed a normal eosinophil level ; the eosinophil count is therefore not likely to be a useful marker in diagnosing small - intestinal anisakiasis . intestinal anisakiasis ( including duodenal anisakiasis ) causes direct damage to the gut wall , whereas the role of an allergenic response in the pathogenesis is not clear . the diagnosis of intestinal involvement is still difficult , and often it is only possible with a histologic specimen . a history of raw fish ingestion within 3 days is the only specific clinical clue to the diagnosis , but it may be missed because the patient is often unaware of the risk .7 imaging may be useful in guiding the diagnosis . plain x - ray is not specific , whereas small - bowel x - ray series may show a localized stenosis due to focal edema .8 sonography provides an easy , noninvasive , inexpensive alternative with high sensitivity , if guided by history and clinical suspicion . a common sonographic finding is a relatively large amount of ascitic fluid and dilatation of the small intestine and marked localized edema of kerckring 's folds .8 serology , if specific ige is used , could be helpful for the diagnosis . in contrast , other techniques ( latex - based agglutination procedures , ouchterlony tests , immunoelectrophoresis , immunofluorescence , indirect hemagglutination , complement fixation , immunoblotting , and enzyme - linked immunosorbent assay [ elisa ] ) are of limited benefit in early diagnosis , because they lack specificity as a result of cross - reactivity with other parasite antigens and are generally unavailable .9 microscopically , a definite diagnosis is confirmed by the recognition of anisakis larvae . the lesions range from diffuse interstitial edema to phlegmonous infiltrate with numerous eosinophils and epithelioid cell granulomas with foreign body giant cells .7 in addition , capsule endoscopy recently revealed small intestine anisakiasis beyond the reach of fiber endoscopy .10 the best treatment for anisakiasis is prophylaxis . the larvae can not survive in temperatures above 60 for 10 minutes or at -20 for 24 hours . if an egd exam reveals that the larvae have invaded the intestine or the stomach wall , then endoscopic removal consists of grasping the body of the worm and slowly pulling it away .5 the patient in our case had duodenal anisakiasis with duodenal ulcer , which is a rarely involved site . additionally , this patient did not have h. pylori or other factors leading to duodenal ulcer , and anisakis did not seem to produce the duodenal ulcer . in the present case , we believe that the possible mechanisms of duodenal anisakiasis accompanied by duodenal ulcer without gastric anisakis were increased gastric acid output , increased gastric emptying , and easily penetrable inflamed mucosa adjacent to the duodenal ulcer . in summary , we experienced a rare case of a 47 - year - old korean male who had duodenal anisakiasis accompanied by duodenal ulcer without gastric anisakis , which was successfully treated by endoscopic removal of anisakis with biopsy forceps .\noutput:\n" }, { "from": "agent", "value": "humans can be incidentally parasitized by third - stage larvae of anisakis species following the ingestion of raw or undercooked seafood . acute gastric anisakiasis is one of the most frequently encountered complaints in korea . however , duodenal anisakiasis with duodenal ulcer had not been reported in korea , despite the habit of eating raw fish . in this case , a 47 - year - old man was hospitalized because of sharp epigastric pain and repeated vomiting after eating raw fish 3 days previously . on admission , esophagogastroduodenoscopic examination revealed an active duodenal bulb ulcer . at 5 mm away from the ulcer margin , a whitish linear worm was found with half of its body penetrating the duodenal mucosa . herein , we report this case of duodenal anisakiasis accompanied by duodenal ulcer ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: thrombotic microangiopathy ( tma ) results from red cell fragmentation and platelet trapping with subsequent microangiopathic hemolytic anemia and thrombocytopenia and represents a final common pathway of a multitude of clinical syndromes . in this paper , we attempt to summarize the salient features of many of these clinical entities and provide suggestions to help guide the efforts to differentiate between them . this is by no means meant to be an exhaustive discussion of these disorders , but rather strives to be a useful summary of some of the important causes of tma . kasabach - merritt phenomenon ( kmp ) typically describes thrombocytopenia and consumptive coagulopathy in the presence of a vascular tumor . however , further research has shown that kmp is most commonly associated with the rare benign vascular tumors kaposiform hemangioendothelioma ( khe ) and tufted angioma ( ta ) . more than 50 % of the cases of khe and ta occur in the first year of life . khe and ta tend to occur on the extremities , neck or trunk , but can sometimes involve the retroperitoneum . for this reason , thrombocytopenia in a newborn unexplained by other routine testing ( such as for sepsis ) should prompt imaging for occult vascular lesions . the pathogenesis of this condition has not been fully elucidated , but to the best of our understanding , the abnormal endothelium of these tumors results in platelet trapping , fibrin deposition with subsequent red blood cell damage , and a consumptive coagulopathy . while microangiopathic features are often apparent , anemia is not a common presenting sign unless significant bleeding has occurred . bleeding into the lesion leads to rapid enlargement of the tumor , continuing the cycle of platelet trapping and activation with consumption of clotting factors . kmp has been reported as having 3040 % mortality , usually due to uncontrolled bleeding , but also secondary to cardiac failure or invasion of vital structures by the lesion . historically , interferon alpha has been used successfully as treatment for kmp , but the side effect of irreversible spastic diplegia , particularly in children under 1 year of age , has led to this drug falling out of favor , though it is still used in some cases . first - line treatment now typically relies upon corticosteroids and vincristine , though no prospective randomized trials have been completed comparing this regimen to an alternate treatment . use of other chemotherapies such as cyclophosphamide , actinomycin - d , and methotrexate and of antiplatelet treatments such as ticlodipine has been reported . there are studies currently underway investigating the benefit of novel therapies such as rapamycin . surgical resection , radiation , and embolization of the lesionsthrombotic thrombocytopenic purpura ( ttp ) has classically been defined as the pentad of microangiopathic hemolytic anemia , thrombocytopenia , fever , and neurological and renal compromise . however , the diagnosis requires only microangiopathic anemia and thrombocytopenia , with or without ischemic organ damage , and not attributable to an alternate recognizable cause . untreated , the mortality of ttp was historically as high as 8090 % . with the use of plasma exchange treatment , the overall mortality has been reduced to 2030 % . the term ttp ( or secondary ttp ) has also been used to refer to microangiopathic hemolytic anemia associated with vasculitis , infection , pregnancy , medication , or which develops post - stem - cell transplant . for the purposes of this section of this paper , we will focus on congenital and idiopathic acquired ttp . recent research has illuminated some of the underlying pathophysiology associated with this disorder , though many questions still remain . ttp is the result of thrombi in the microcirculation , leading to thrombocytopenia and microangiopathic hemolytic anemia due to red cell damage within the microthrombi . one of the most exciting developments in the field of ttp has been the identification of the von willebrand factor - cleaving protease , adamts13 ( a disintegrin and metalloprotease with thrombospondin type 1 repeats ) . this enzyme is responsible for the cleavage of extra large multimers of von willebrand factor ( vwf ) into smaller moieties . the lack of this enzyme , either constitutionally or acquired , has been linked to the development of ttp . this phenomenon does not account for all of the cases of ttp , however , and further research is required to explain the complete link between this enzyme and the clinical variability of the disease . idiopathic ttp typically occurs due to the development of autoantibodies to adamts13 , usually type g immunoglobulins . patients ' risk of relapse is somewhat predicted by very low adamts13 levels at diagnosis . however , variations in adamts13 activity and inhibitor levels after treatment has been completed have not been consistently predictive of pending relapse , putting the utility of following these levels into question . plasma infusion or exchange is the mainstay of treatment for acquired ttp . additional treatment modalities such as steroids , vincristine , cyclophosphamide , antiplatelet agents , and rituximab ( anti - cd20 antibody ) have also been used to varying success . inherited ttp , also known as upshaw - schulman syndrome , results from genetic mutations in the adamts13 gene and represents approximately 10 % of those patients with ttp . this is an extremely rare disorder , estimated to have an incidence of only 1 : 1,000,000 . it is inherited in an autosomal recessive pattern , sometimes homozygously , but more often due to compound heterozygosity , and penetrance can be variable within the same family . most patients present in infancy , but there are patients who have presented during the second or third decades of life , and there are individuals who are known to carry mutations who show no symptoms . this has led to the hypothesis that , in some individuals carrying 2 mutations , an additional triggering event in conjunction with low adamts13 levels is required to develop ttp . in addition , a novel aptamer which blocks platelet activation in ttp is currently under investigation and has completed phase i studies . gene therapy has also been suggested as a treatment for this disorder , though research is still in the preclinical stages . hemolytic uremic syndrome ( hus ) is characterized by microangiopathic hemolytic anemia and thrombocytopenia with accompanying renal impairment . it can be divided into 3 subtypes : diarrhea - associated hus ( d + hus ) , pneumococcal ( also known as atypical or diarrhea negative ) hus , and congenital hus ( which has also been referred to as atypical ) . while the three entities share clinical features , the underlying epidemiology , pathogenesis , and treatment are markedly different . like ttp , the term hus has been used to refer to a spectrum of thrombotic microangiopathy caused by medications or associated with pregnancy or other clinical conditions . we will only address the three entities listed above in this section of the paper . it usually occurs in children and is most commonly caused by infection with shiga - toxin producing escherichia coli o157 ( stec ) . the mean incidence of hus in children under 18 years of age ranges from 0.28 to 0.71 cases per 100,000 persons . the disease is more common in those 5 years of age , in whom the mean incidence has been reported between 0.85 and 1.87 cases per 100,000 children . d + hus is also the most common cause of acute renal failure in children in the usa . mortality ranges from 1 to 33 % with the highest mortality in those 60 years of age . the pathogenesis of d + hus results from the production of shiga - toxins ( stx ) by the infective e. coli . while the most common type of e. coli associated with this illness is the o157 : h7 strain , it is well known that other strains of e. coli may also produce stx . stec lead to a food - or water - borne diarrheal illness that can be bloody or nonbloody . the disease progresses to hus due to the release of stx in the intestine , which then are translocated across the gut epithelium into the circulation . the primary locations of gb3 in the human body are vascular endothelial cells , particularly in the glomeruli . exposure to stx damages the endothelium , resulting in the release of tissue factor and exposure of the platelets to extra large von willebrand factor multimers and collagen . this then triggers activation of the platelets and the coagulation cascade and leads to thrombus formation . the impact of the actions of stx in these locations results in microangiopathic hemolytic anemia and thrombocytopenia . in addition , stx has also been shown to bind to and directly activate platelets via the gb3 receptor . there have been recent studies regarding synsorb pk , an agent composed of silicone dioxide particles linked to the pk trisaccharide that is responsible for stx binding to the endothelial cell surface . monoclonal antibodies to stx are also under investigation . in experimental studies in mice these antibodies have been shown to neutralize stx . hus associated with pneumococcal infection ( d - hus or p - hus ) is one of the atypical forms of hus . it is much less common that d + hus accounting for only approximately 510 % of hus cases overall , though it may be responsible for as many as half of d - hus cases . it has been associated with a higher morbidity and mortality than d + hus , though increased awareness and improved treatment has improved this finding . p - hus tends to occur in very young children , with the average age typically under 1 year . the overall mortality rate is currently approximately 10 % , which is much improved from previous reports of mortality from 2950 % . streptococcus pneumoniae release neuraminidase , an enzyme that results in desialylation of red blood cell membrane proteins and exposure of the thomsen - friedenreich cryptantigen ( t - antigen ) . the t - antigen is a ubiquitous antigen on human blood cells to which all people have igm antibodies . it is not clear if these symptoms are antibody mediated or are a result of another mechanism . in addition , supportive care with dialysis may be required for those patients in kidney failure . many patients require blood product transfusion , though exposure to plasma should be limited because of the possibility of worsening the hemolysis due to infusion of igm anti - t antibody . vaccination against pneumococcus would reasonably be expected to reduce the prevalence of p - hus , since the most common serotypes associated with hus are included in the vaccine . however , it has recently been shown that serotype 19a may have emerged as an important invasive pathogen leading to p - hus . it is thought that up to one - third to one - half of patients with ahus have a mutation in one of the complement regulatory proteins . the deficiency of factor h , a regulatory glycoprotein in the alternative complement pathway , leads to a form of congenital hus . the absence leads to overactivity of the alternative complement pathway and subsequent features of hus . mutations causing deficiencies in factor i , c3 , and membrane cofactor protein cd46 have also been reported . gain - of - function mutations in complement factor b and c3 , have been identified in families with ahus and persistent activation of the alternative complement pathway . families carrying mutations show incomplete penetrance of disease and may be modulated by the presence or absence of other complement gene variants . autoantibodies to factor h which develop in individuals with mutations in factor h related proteins 1 and 3 have also been implicated in the pathogenesis of the disease . the prognosis for ahus is grim , with mortality approaching 25 % in the acute phase and as many as 50 % of patients developing end stage renal disease . if transplantation is attempted , 60100 % of patients will experience a relapse , which almost inevitably results in loss of the renal graft . treatment relies on infusion of plasma which contains the missing factor . in the case of those patients with autoantibodies , recent studies regarding the use of the recombinant complement inhibitor eculizumab have been promising , particularly in those patients who have failed plasma - replacement therapy . microangiopathic hemolytic anemia ( maha ) , also called posttransplant thrombotic microangiopathy ( ta - tma ) has been described as a complication of bone marrow transplantation , both autologous and allogeneic with variable incidence rates ranging from 0 to 74 % depending on the diagnostic criteria used to make the diagnosis . it is also a well - known complication following solid organ transplants , such as kidney transplants , with a variable time from transplant to diagnosis and could be due to viral infections , arise de novo , or be related to the use of calcineurin inhibitors , mainly the microemulsion form of cyclosporine . tma was observed in 26 of 188 patients with renal transplants with an incidence of 14 % with the majority of these patients having no systemic manifestation of tma . it has also been reported following liver transplantation ; five of 100 patients who received living donor liver transplant ( ldlt ) developed tma with an incidence of 5 % and at a median interval of 18 days following transplant . another major factor in the development of tma is drugs used for graft versus host disease ( gvhd ) , mainly fk506 and cyclosporine or with other gvhd prophylaxis . factors that can contribute to this condition include high - dose chemotherapy for autologous stem cell transplant ( asct ) , conditioning regimen for allogeneic stem cell transplant , total body irradiation , and use of immune suppressive therapy . the role of gvhd and renal involvement in the pathogenesis of ta - tma has also been investigated . reviewed 314 renal autopsies on patients who died after their first hematopoietic stem cell transplant over a 7 - year period . twenty percent of autopsies reviewed showed tma , with an additional 15 % with evidence of thrombus formation . the risk of tma in that patient population increased 4-fold with incidence of acute gvhd , independent of the use of cyclosporine . the presence of acute gvhd was an independent risk factor in the development of ta - tma in the multivariate analysis in addition to sex mismatch , higher doses of total body irradiation ( tbi ) , and viral infections . in addition to the significant renal involvement with acute gvhd , ta - tma has also been found to involve the gut tissue . in a study of 16 patients with ta - tma , all were found to have acute gvhd . seven patients were retrospectively diagnosed with ta - tma , while 9 were specifically investigated for it . all patients that were retrospectively diagnosed died as a result of increasing the immune suppression intensity due to the impression that it was purely gut gvhd , while 8 of the other nine patients improved following reduction of immune suppression . infections have also been shown to be associated with maha after transplant ; bacterial infection with helicobacter pylori was found to be associated with six patients among 74 consecutive transplants through involvement of elevated cytokines . viral infections such as parvob - 19 , cmv , and hhv - 6 have also been implicated as a cause of ta - tma . typically postinfectious cases are due to reactivation of these viruses within the first 36 months after transplant . viral infections should be considered in recipients of transplant who develop refractory cases of ta - tma . pregnancy - associated thrombotic microangiopathy is a rare but serious disorder that is associated with significant maternal and perinatal morbidity and mortality , due to the deposition of fibrin and platelet thrombi in the microcirculation of the placenta . it has been reported to occur in 1 : 25,0001 : 100,000 pregnancies . pregnancy can precipitate the disease for the first time or can exacerbate the recurrence of an existent condition . pregnancy - associated microangiopathy typically occur during late pregnancy ; however , it has also been reported in the first trimester of pregnancy , in which case the patient was managed very intensely with continuous plasma therapy throughout the pregnancy . both mother and fetus survived without complications . in reviewing the oklahoma ttp - hus registry in 335 patients , terrell et al . did not find any gender or race predilection that was associated with pregnancy - associated microangiopathy , as well as with hematopoietic stem cell transplant or drugs . recently published data on the largest collection of pregnancy - associated microangiopathy encompassing over 4 decades . one hundred and sixty - six patients with pregnancy - associated thrombotic thrombocytopenic purpra were reported on . patients either had their first episode ( n = 106 ) or recurrent episode ( n = 32 ) . median time presentation was 23.79 weeks and 2210 weeks , respectively . the only significant laboratory differences between both groups were hemoglobin and hematocrits ( 6.8 versus 11.4 g / dl and 19 % versus 25 % , resp . ) . perinatal and maternal mortalities were high in both groups ( 32 % versus 44 % and 26 % versus 10.7 % ) ; however , both mortality rates were significantly lower in the years after 1980 compared to before that year . one of the confusing clinical pictures was the association of pregnancy - associated ttp and hellp syndrome ( hemolysis , elevated liver enzymes , low platelets ) , which had both preeclampsia / eclampsia and ttp concurrently . this was reported in 29 of the 166 patients in the series and significantly increased maternal mortality from 21.8 % to 44.4 % . pregnancy - associated microangiopathy can be confused with other medical and obstetrical conditions such as severe preeclampsia / eclampsia , hellp syndrome , sepsis , and pregnancy - induced fatty liver changes . the confusion in making the diagnosis usually happens due to the non - specific clinical and laboratory criteria needed to make the diagnosis . this is more of a problem when the initial management is done by physicians who are not accustomed to taking care of these patients . stella et al . reported on 14 cases of pregnancy - associated microangiopathy in 12 pregnancies by reviewing the charts of these patients .4 / 12 cases were evaluated in the er initially and were given the diagnoses of domestic violence , gastroenteritis , itp , and panic attack .8 / 12 patients were seen by obstetric services ; however , all were given the wrong diagnosis , mainly hellp syndrome , despite of being normotensive and having no proteinuria . half of the patients in the series were diagnosed before 24 week gestation but only 3 had term live births . over the last 2 decades , there has been increasing evidence that adamts13 is significantly involved in the pathogenesis of pregnancy - associated microangiopathy . this could be due to congenital deficiency of the enzyme activity which is usually severe or due to the presence of inhibitors with less sever deficiency . however , some patients with pregnancy - associated microangiopathy were found to have a normal enzyme activity while other patients with ttp due to other clinical syndromes had low enzyme activity . the congenital deficiency of the adamts13 activity is also known as upshaw - schulman syndrome ( uss ) . in their research paper , fujimura andnine females with a total of 15 pregnancies developed significant thrombocytopenia during the second half of their pregnancies leading to stillbirth in 8 out of total 16 babies . eight of the nine women had heterozygous mutations and only one had a homozygous abnormality . although adamts13 enzyme deficiency ( both congenital and acquired ) is the main underlying mechanism in pregnancy - induced microangiopathy , dysregulation of alternative c3 convertase enzyme , due to mutations in the gene coding for the protein has also been shown to cause an atypical form of hus during pregnancy ( mainly with renal involvement and not due to shiga toxin ) . in a retrospective analysis of 100 women with this rare and ill - defined type of hus , it was found to be associated with pregnancy in 21 patients ( 21 % incidence ) . the disease occurred during the first pregnancy in 38 % and occurred mainly during postpartum period ( 79 % ) . the unusual feature of this syndrome was the disproportionate severe renal involvement compared to the thrombocytopenia ; 81 % of patients required hemodialysis during the acute phase while 61 % eventually reached end - stage renal disease in less than a month from the beginning of the episode . a variety of the therapeutic interventions have been tried with pregnancy - induced microangiopathy ( and other forms of ttp ) with limited success . therapies such as steroids , antiplatelet agents , ivig , and even splenectomy have been tried . not until plasma infusion and plasma exchange were introduced that the survival rate increased from 10 % up to 80 % currently . plasma exchange and / or plasma infusion need to be initiated whenever there is a good suspicion of microangiopathy . in general this therapywill have to be continued to the end of delivery or throughout the postpartum period . one of the clinical dilemmas when it comes to systemic vasculitis is the overlap of manifestations of both disorders . one of the earliest reports has been by ross et al . in 1996 when they reported the incidence of 2 cases of maha that was associated with a case of wagner 's granulomatosis with positive antineutrophil antibodies ( ancas ) and another case of guillain - barre syndrome with positive nerve biopsy for anca with specificity to myeloperoxidase . a more common association of systemic autoimmune disorders and maha is usually with systemic lupus erythematosus ( sle ) , with large number of case reports and small case series . in a single - institution large series of patients with sle and maha , kwok et al . twenty - six patients were found to have maha in addition to their sle diagnosis - 87 patients without maha matched for age and sex were also included as controls . the study showed that sle is an independent risk factor for the development of microangiopathy and that this risk was associated with higher sle disease activity index ( sledai ) . the study also showed that infection was the only independent risk factor for mortality for those ttp patients . maha has been also reported in a large variety of connective tissue disorders other than sle , including systemic sclerosis , rheumatoid arthritis , dermatomyositis , and still 's disease . similar to other conditions with microangiopathy and maha , adamts 13 enzyme has been linked to the pathophysiology of maha in autoimmune disorders . severe reduction in the enzyme activity as well as the presence of inhibitors has been consistently found in patients with sle and other similar disorders . since adamts 13 deficiency is considered very rare in sle and similar disorders with maha , testing for this enzymeis considered a good method to distinguish between the two . maha is a rare disorder that has the hallmark of fragmented red blood cells and thrombocytopenia that is nonimmune in nature . maha is not a single disease or even a single group of disorders ; rather it is a spectrum of disorders that usually present as an hus / ttp picture . ttp / hus is caused by a vast array of different agents ( drugs , toxins , infections , pregnancy , and autoimmunity ) that damage the endothelium via multiple and varied mechanisms . functionally altered endothelium provokes intravascular platelet aggregation , resulting in the variable clinical manifestations of the syndrome . because of the rarity of these disorders and the nonspecific clinical and laboratory features , this diagnosis ( and its underlying causes ) can be easily overlooked or missed leading to the high morbidity and mortality that can be seen with this problem . therefore , when a patient presents with unexplained thrombocytopenia and a coombs - test - negative hemolytic anemia , a presumptive diagnosis of maha should be considered . one of the newer advancements in the management of this disorder is the discovery of association of the adamts13 enzyme 's level and activity with ttp that has led to earlier and improved detection rate which was translated to better survival . no specific therapy can be claimed to cure this group of disorders , however , few interventions have been proven to be helpful ( and even life saving ) in some disorders such as the use of plasma infusion and plasma exchange in the management of ttp .\noutput:\n" }, { "from": "agent", "value": "thrombotic microangiopathy results from thrombotic occlusion of the microvasculature leading to fragmentation of red blood cells , profound thrombocytopenia , and a microangiopathic hemolytic anemia with elevation of lactate dehydrogenase and negative direct coomb 's test . this constellation of clinical and laboratory findings is not due to one disease entity ; rather , it represents a variety of underlying diagnoses . among the major disease entities are ttp / hus , which can be congenital or acquired , bacterial infections , medications , vascular or endothelial pathology like kasabach - merritt phenomenon , and stem cell transplantation . in this paper , we offer a review of some of the major causes of thrombotic microangiopathy ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the participants were selected from the ongoing tbingen family study for type 2 diabetes ( 11 ) . in short , the aim of this study is to investigate individuals at high risk but yet without known type 2 diabetes . we selected 1,576 subjects for which complete oral glucose tolerance test ( ogtt ) data and genotypes were available . according to the world health organization diagnostic criteria ,1,079 subjects were identified as normal glucose tolerant ( ngt ) , 143 showed impaired fasting glucose ( ifg ) , 138 had impaired glucose tolerance ( igt ) , and 112 had both ifg and igt . in 82 subjects , the clinical characteristics of the study population are shown in supplementary table 1 in the online appendix available at http://diabetes.diabetesjournals.org/cgi/content/full/db10-0674/dc1 . informed written consent was obtained from all participants , and the local ethics committee approved the protocol . we also analyzed longitudinal data from a subgroup of 342 individuals who were metabolically reanalyzed after a follow - up period of 9 months , during which they took part in a lifestyle intervention program ( see the online appendix for additional information ) . we selected representative snps in type 2 diabetes risk loci previously reported to affect distinct aspects of - cell function : kcnj11 ( rs5215 ) , slc30a8 ( rs13266634 ) , cdkal1 ( rs7754840 ) , cdkn2a / 2b ( rs10811661 ) , mtnr1b ( rs10830963 ) , tcf7l2 ( rs7903146 ) , wfs1 ( rs10010131 ) , hhex ( rs7923837 ) , kcnq1 ( rs151290 ) , and igf2bp2 ( rs4402960 ) . all snps were genotyped in the whole cohort in the course of earlier studies ( 1218 ) using taqman assays ( applied biosystems , foster city , ca ) and passed the quality controls . details on this as well as on minor allele frequencies , genotyping success rates , and hardy - weinberg equilibrium are reported in the aforementioned references . after an overnight fast , subjects ingested a standard solution containing 75 g of glucose at 08:00 h. plasma glucose , insulin , and c - peptide concentrations were determined in venous blood samples obtained at 0 , 30 , 60 , 90 , and 120 min . plasma insulin and c - peptide were determined by commercial chemiluminescence assays for advia centaur ( siemens medical solutions , fernwald , germany ) . blood glucose was measured using a bedside glucose analyzer ( glucose oxidase method ; yellow springs instruments , yellow springs , oh ) . insulinogenic index ( igi ) was calculated from the ogtt ( [ insulin30 insulin0 ] / [ glucose30 glucose0 ] ) . areas under the curve ( aucs ) were calculated according to the trapezoid method as : 0.5 ( c0 / 2 + c30 + c60 + c90 + c120 / 2 ) where c is concentration . data that were not normally distributed were logarithmically transformed prior to statistical analysis . to identify covariates interacting with snp effects on insulin secretion , we used ancova . p values 0.05 were considered to indicate nominal associations , after correction for multiple comparisons taking into account the 10 genes tested ( according to bonferroni correction ) . after correction for multiple comparisons taking into account the 2 genes tested further ( according to bonferroni correction ) , p values 0.025 were considered statistically significant . for statistical analysis , jmp 7.0 ( sas institute , cary , nc ) statistical software package was used . we selected representative snps in type 2 diabetes risk loci previously reported to affect distinct aspects of - cell function : kcnj11 ( rs5215 ) , slc30a8 ( rs13266634 ) , cdkal1 ( rs7754840 ) , cdkn2a / 2b ( rs10811661 ) , mtnr1b ( rs10830963 ) , tcf7l2 ( rs7903146 ) , wfs1 ( rs10010131 ) , hhex ( rs7923837 ) , kcnq1 ( rs151290 ) , and igf2bp2 ( rs4402960 ) . all snps were genotyped in the whole cohort in the course of earlier studies ( 1218 ) using taqman assays ( applied biosystems , foster city , ca ) and passed the quality controls . details on this as well as on minor allele frequencies , genotyping success rates , and hardy - weinberg equilibrium are reported in the aforementioned references . after an overnight fast , subjects ingested a standard solution containing 75 g of glucose at 08:00 h. plasma glucose , insulin , and c - peptide concentrations were determined in venous blood samples obtained at 0 , 30 , 60 , 90 , and 120 min . plasma insulin and c - peptide were determined by commercial chemiluminescence assays for advia centaur ( siemens medical solutions , fernwald , germany ) . blood glucose was measured using a bedside glucose analyzer ( glucose oxidase method ; yellow springs instruments , yellow springs , oh ) . insulinogenic index ( igi ) was calculated from the ogtt ( [ insulin30 insulin0 ] / [ glucose30 glucose0 ] ) . areas under the curve ( aucs ) were calculated according to the trapezoid method as : 0.5 ( c0 / 2 + c30 + c60 + c90 + c120 / 2 ) where c is concentration . data that were not normally distributed were logarithmically transformed prior to statistical analysis . to identify covariates interacting with snp effects on insulin secretion , we used ancova . p values 0.05 were considered to indicate nominal associations , after correction for multiple comparisons taking into account the 10 genes tested ( according to bonferroni correction ) . after correction for multiple comparisons taking into account the 2 genes tested further ( according to bonferroni correction ) , p values 0.025 were considered statistically significant . for statistical analysis , jmp 7.0 ( sas institute , cary , nc ) statistical software package was used . we screened for the interaction of 120 min postload glucose ( glucose120 ) , auc of glucose , and a1c with effects of the 10 snps on the insulin secretion parameters aucc - peptide / aucglucose and igi by ancova . after correction for multiple comparisons , tcf7l2 snp rs7903146 and wfs1 snp rs10010131 showed significant interaction with aucglucose and glucose120 concerning their effect on insulin secretion measured by c - peptide or insulin - derived secretion indexes . for the other 8 snps , only a few interactions with secretion parameters were detected ( table 1 ) , which did not pass correction for multiple comparisons . interaction of glucose120 , aucglucose , and a1c with snps on insulin secretion data are p values determined using the additive inheritance model . therefore , we stratified the cohort for genotypes and plotted insulin secretion values against glucose120 as a proxy for glycemia . insulin secretion was adjusted for possible confounders ( sex , age , bmi , and insulin sensitivity ) by multivariate linear regression analysis . the compromising effect of the risk alleles on insulin secretion is most apparent under high glucose conditions for the tcf7l2 snp rs7903146 as well as for the wfs1 snp rs10010131 . by contrast , when glucose levels are low , no snp effect on insulin secretion is obvious or the risk allele may even be beneficial . in this respect , the t - allele of tcf7l2 snp rs7903146 appears to affect insulin secretion in a recessive way , whereas the mode of action of the g - allele of wfs1 snp rs10010131 is less clear . performing similar analyses for2 ) . association between igi and glucose 120 min by tcf7l2 snp rs7903146 ( a ) and wfs1 snp rs10010131 ( b ) . association between aucc - peptide / aucglucose and glucose120 by tcf7l2 snp rs7903146 ( c ) and wfs1 snp rs10010131 ( d ) . data were loge - transformed prior to statistical analysis and adjusted for sex , age , bmi , and ogtt - derived insulin sensitivity index by multivariate linear regression analysis . to further evaluate the interaction of tcf7l2 rs7903146 and wfs1 rs10010131 with acute glucose - dependent insulin secretion , we plotted c - peptide levels at 30 min of the ogtt against glucose levels at the same time point . at this time , variation of glucose is most pronounced and c - peptide levels are hardly influenced by clearance . c - peptide was adjusted for possible confounders ( sex , age , and bmi ) by multivariate linear regression analysis . in carriers of the nonrisk alleles of the tcf7l2 and wfs1 snps , by contrast , this relation is blunted in carriers of the risk alleles ( fig .2 ) . using insulin instead of c - peptide yielded comparable results ( supplementary fig .1 ) . association between c - peptide levels at 30 min of the ogtt and glucose levels at 30 min during the ogtt by tcf7l2 snp rs7903146 ( a ) and wfs1 snp rs10010131 ( b ) . c - peptide data are adjusted for sex , age , and bmi by multivariate linear regression analysis . furthermore , we tested whether glycemia influences the impact of genetic variance in tcf7l2 on changes in insulin secretion during a longitudinal lifestyle intervention study . we found a significant interaction between tcf7l2 genotype and glycemia ( glucose at 120 min of the ogtt ) at baseline on change in insulin secretion ( p value using the dominant inheritance model = 0.0027 ) in a model including sex , age , insulin secretion at baseline , change in bmi , and change in glucose at 120 min of the ogtt . participants with igt at baseline who carried the t risk allele showed a significant increase in insulin secretion during lifestyle intervention compared with participants with ngt at baseline . no differences in change of insulin secretion between subjects with ngt and igt were present in carriers of the wild - type c - allele ( fig . , we found no significant interaction using the same model as described above ( p = 0.5 ) . associations between fold - change in insulin secretion ( measured by igi ) during 9 - month lifestyle intervention and at baseline glucose tolerance status . participants with igt at baseline who carried the t risk allele showed a significant increase in insulin secretion compared with participants with ngt at baseline . no differences in change of insulin secretion between subjects with ngt and igt were present in carriers of the wild - type c - allele . in the present study , we demonstrated an interaction between snp effects on insulin secretion and glucose levels for 2 of the 10 tested snps , i.e. , in tcf7l2 rs7903146 and wfs1 rs10010131 . both snps were found to impair incretin - stimulated insulin secretion ( 13,15 ) . it is well known that incretins are biologically effective only under high glucose conditions ( 9 ) . therefore , it seems plausible that the effects of these variants are more pronounced when glucose levels are elevated . the genetic variation in the other diabetes risk genes associated with reduced insulin secretion ( kcnj11 , slc30a8 , cdkal1 , cdkn2a / 2b , mtnr1b , hhex , kcnq1 , and igf2bp2 ) did not show such an interaction . therefore , their impact is constantly present over the whole range of glucose levels from ngt to igt and overt diabetes . insulin secretion is markedly impaired in carriers of the risk alleles when glucose levels reach values defining igt . thus , it may be important to lower glucose levels early in subjects with these risk variants as a primary prevention in subjects in the prediabetic and pre - igt states . to test this hypothesis , we analyzed the change in insulin secretion during a lifestyle intervention with improving glycemia in relation to baseline glycemia and genetic variation in tcf7l2 . we took advantage of the tbingen lifestyle intervention program ( tulip ) , which uses an intervention similar to those of the finnish diabetes prevention study ( dps ) and u.s . diabetes prevention program ( dpp ) ( 19,20 ) . this intervention , based on dietary advice and increase of physical activity , improves mainly insulin sensitivity ( 11 ) . we previously reported that the risk allele of tcf7l2 rs7903146 is associated with less weight loss in response to this lifestyle intervention ( 21 ) . however , in our present analysis , we found that increased glucose levels before lifestyle intervention predicted an increase in insulin secretion in carriers of the risk alleles of tcf7l2 rs7903146 . thus , specifically subjects with igt on the eve of diabetes who carry the tcf7l2 rs790314 risk allele profit from dietary and exercise interventions designed to lower glucose levels by improving insulin sensitivity . a plausible explanation may be that the relative impairment of the incretin effect in carriers of the risk allele is secondary to chronic hyperglycemia , and thus the lifestyle intervention , by normalizing the hyperglycemia in these subjects , would also restore the insulinotropic effect of incretins . these findings are consistent with the findings of the dps and dpp studies , in which the tcf7l2 genotype has an effect on the progression from igt to diabetes in the control group but not in the lifestyle intervention group ( 22,23 ) . on the basis of our data , we hypothesize that improving blood glucose by improving insulin sensitivity as was achieved by lifestyle intervention in the dps , dpp , and tulip studies reduces the need for compensatory insulin hypersecretion . therefore , the contribution of incretin action on insulin secretion that is impaired in risk allele carriers becomes less important . the interaction of glycemia with genetic variation in genes associated with insulin secretion also has further implications for gentopye - phenotype association studies . the interaction between genetic and environmental factors such as glucose control may hinder the detection of other snps in cross - sectional studies ( 24 ) . to avoidthis , knowledge of such environmental factors might be of great value when analyzing case - control data , and additional prospective studies controlling for them should be performed . a question raised by our data is whether snps with stronger effects under high glucose conditions determine the further progression toward the disease . one might hypothesize that effects of the risk allele suppress insulin secretion even stronger in the igt state and therefore might accelerate conversion toward type 2 diabetes . to test this assumptionis the fact that we could only detect relatively large effect sizes , and the study was therefore underpowered to detect smaller effect sizes . indeed , because we tested 10 snps in parallel , only 2 of them reached statistical significance after bonferroni correction . thus , to verify our findings , additional studies in larger cohorts including subjects with other ethnic backgrounds are needed . for example , we did not detect an interaction effect of wfs1 and glucose levels at baseline on change in insulin secretion in the longitudinal lifestyle intervention study . this might be due to the relative low number of subjects that could be included in this analysis . furthermore , our cohort was also not balanced between sexes and a single ogtt was used to measure glucose levels for each participant , thus not taking into account day - to - day variability . the fact that we observed interactions with 120 min glucose but not with a1c may be due to the relatively low power of the study or to glycemia - independent factors that alter a1c levels . taken together , we found that glucose control determines the effects of certain snps on insulin secretion . the effects of both tcf7l2 rs7903146 and wfs1 rs10010131 worsen with rising glucose levels , and both snps are associated with impaired incretin action on insulin secretion . this indicates the relevance of snps in different stages of the pathogenesis toward type 2 diabetes ( 7,25 ) as well as prevention strategies for type 2 diabetes .\noutput:\n" }, { "from": "agent", "value": "objectiveseveral single nucleotide polymorphisms ( snps ) in diabetes risk genes reduce glucose - and / or incretin - induced insulin secretion . here , we investigated interactions between glycemia and such diabetes risk polymorphisms.research design and methodsinsulin secretion was assessed by insulinogenic index and areas under the curve of c - peptide / glucose in 1,576 subjects using an oral glucose tolerance test ( ogtt ) . participants were genotyped for 10 diabetes risk snps associated with - cell dysfunction : rs5215 ( kcnj11 ) , rs13266634 ( slc30a8 ) , rs7754840 ( cdkal1 ) , rs10811661 ( cdkn2a / 2b ) , rs10830963 ( mtnr1b ) , rs7903146 ( tcf7l2 ) , rs10010131 ( wfs1 ) , rs7923837 ( hhex ) , rs151290 ( kcnq1 ) , and rs4402960 ( igf2bp2 ) . furthermore , the impact of the interaction between genetic variation in tcf7l2 and glycemia on changes in insulin secretion was tested in 315 individuals taking part in a lifestyle intervention study.resultsfor the snps in tcf7l2 and wfs1 , we found a significant interaction between glucose control and insulin secretion ( all p 0.0018 for glucose genotype ) . when plotting insulin secretion against glucose at 120 min ogtt , the compromising snp effects on insulin secretion are most apparent under high glucose . in the longitudinal study , rs7903146 in tcf7l2 showed a significant interaction with baseline glucose tolerance upon change in insulin secretion ( p = 0.0027 ) . increased glucose levels at baseline predicted an increase in insulin secretion upon improvement of glycemia by lifestyle intervention only in carriers of the risk alleles.conclusionsfor the diabetes risk genes tcf7l2 and wfs1 , which are associated with impaired incretin signaling , the level of glycemia determines snp effects on insulin secretion . this indicates the increasing relevance of these snps during the progression of prediabetes stages toward clinically overt type 2 diabetes ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: myocardial perfusion spect ( mps ) is an imaging procedure that utilizes an intravenously administered radiotracer to delineate the distribution of blood flow in the myocardium during exercise or pharmacological stimulation and at rest using tomographic camera . patients with hemodynamically significant coronary artery stenosis will have a myocardial region of diminished radiotracer concentration in areas of diseased vessels , which constitute the basis of diagnosing coronary artery disease ( cad ) with mps . if the perfusion abnormality shown on mps is worse at stress than at rest , the so - called reversible defect , the myocardial segment is most likely due to ischemia ( fig . if the perfusion abnormality remains unchanged from stress to rest ( fixed defect ) , the lesion usually indicates scarred myocardium ( fig . the major indications of mps are used for evaluation of patients with suspected or known cad , including assessment of the presence , location , extent and severity of myocardial ischemia and scar , determination of the functional significance of anatomic stenosis detected by invasive or ct coronary angiography , and assessment of myocardial viability in ischemic cardiomyopathy . plenty of published studies had confirmed the diagnostic accuracy of mps in detecting obstructive cad when using the diameter stenosis of diseased vessels demonstrated on coronary angiography . as a functional modality for assessing the hemodynamic significance of coronary lesion , mpshad also established its role in risk stratification and prognostic assessment in patients with cad . the patients with normal or near - normal results on mps would have an annual cardiac event rate of less than 1 percent . in addition , those showing normal perfusion or only mild ischemia on mps could be safely managed with conservative medical treatment rather than invasive revascularizations . for those with moderate to severe ischemia on mps , however , revascularization significantly improves the survival in comparison with medication only . therefore , mps has been clinically considered as a gatekeeper of invasive procedure in the management of cad . in gated image acquisition of mps , ecg provides the r wave trigger to the acquisition computer , with 2 successive r wave peaks on the ecg for defining a cardiac cycle . reconstruction of 3d images of the left - ventricular ( lv ) myocardium at different time points over the cardiac cycle allows calculation of end - systolic volume ( esv ) , end - diastolic volume ( edv ) and ejection fraction ( ef ) . cinematic display of mps images at different cardiac cycles enable readers to assess wall motion ( wm ) and wall thickening ( wt ) in all segments of the myocardium ( fig . the application of ecg - gating technique in mps enables the simultaneous assessment of lv perfusion and function in a single imaging modality . these functional parameters not only provide invaluable information on diagnosis and prognosis of cardiac disease but also are useful for differentiation of attenuation artifacts from true myocardial injuries . gated mps now has become the standard procedure for myocardial perfusion imaging in the nuclear medicine labs worldwide . the mechanism of myocardial perfusion imaging ( mpi ) in detecting coronary artery disease ( cad ) is primarily based on the detection of perfusion abnormalities of lv myocardium caused by the coronary flow gradients between normal and diseased arteries , which results in differences in tracer uptake in respective myocardial territories . in patients with multivessel cad , however , the perfusion abnormalities may be unremarkable , or even be missed due to relatively balanced hypoperfusion between the stenosed vessels . a pervious study found that the performance of detecting flow - limited cad with mps was very limited in patients with stenoses in multiple coronary vessels ; thereby , the diagnostic sensitivity was as low as only 48 % .4 shows the perfusion images from an 82 year - old male patient who presented with typical angina pectoris and was referred for stress mps test for diagnosis and risk stratification of suspected cad . only unremarkably reversible perfusion abnormality was noted in the apical anterior segment , and conservative management was initially suggested based on the result of mps . however , he was still referred to receive invasive coronary angiography due to exacerbating symptoms . the angiography revealed an extensive and severe cad in multi - coronary vessels , including 60 % stenosis in the left main artery , 95 % in the proximal left anterior descending artery and 70 % in the right coronary artery . this patient was thereafter referred for receiving invasive revascularization procedure of coronary artery bypass grafting . the images reveal poor lv function with an ef of 36 % , and impaired regional wall motion in anterior , septal and inferior walls . the images show only minimally reversible perfusion abnormality in apical anterior segment of lv , which apparently underestimates the severity of cad . this patient developed a cardiac event of acute myocardial infarction with confirmed three - vessel cad by invasive coronary angiography after one and a half years after mps study . transient ischemic dilation ( tid ) refers to a significant enlargement in lv size on the stress images compared to the rest images on mps . the presence of tid , either in exercise or pharmacologic stress protocols , has already been found to be highly indicative of severe and extensive cad and also predictive of high cardiac - event risk . abdidov et al . further studied the prognostic value of tid in patients with normal mps . they found that an entirely normal stress mps did not always imply an excellent prognosis . they concluded that tid was an independent and incremental prognostic marker of total cardiac event even for patients with otherwise normal mps , and the interpreter should be very cautious in making low - risk prognostic statements , especially in patients with typical angina , the elderly , and diabetics .5 shows the perfusion images of a 63 year - old male patient who presented with exertional shortness of breath and was referred for stress mps as a work - up of suspected cad . there is completely normal perfusion in all myocardial areas on both stress and rest images , except for an apparent tid . based on the normal perfusion and the ignorance of prognostic significance of tid , the patient was managed with conservative medical treatment only without further imaging studies . unfortunately , acute myocardial infarction involving the anterior wall developed one and a half years later . an emergent invasive coronary angiography revealed total occlusion of left anterior descending artery , 60 % stenosis in left circumflex artery and 70 % stenosis in right coronary artery . the most widely accepted explanation is myocardial thinning resulting from stress - induced diffuse subendocardial hypoperfusion , which produces a visually larger lv cavity . at rest , the subendocardium is better perfused and the lv cavity appears smaller . conducted an interesting study , which assessed the relationship of tid and stress - induced changes of functional variables using early post - stress and rest tl - 201 gated mps . they found that tid was significantly correlated with stress - induced ischemic stunning , as manifested by dropping lvef and worsening of regional wm at stress .6 . a 61 - year - old female patient was found to have 3 - vessel disease ( 80 % stenosis in the proximal left anterior descending , 100 % in the mid left circumflex and 100 % in the right coronary arteries ) on invasive coronary angiography . the mps images revealed reversible perfusion defects involving the apex , septum , inferior wall and lateral wall , and also prominent tid . functional analyses of gated mps revealed a severely depressed lvef of 33 % on stress and returned to 52 % on rest . the regional wm abnormality was also more severe at stress than at rest , and the enlargement of esv was significantly greater than that of edv . the volumes are 66 ml on stress images and 41 ml on rest with a ratio , 1.61 ( much greater than the reference cut - off value of 1.19 ) . in addition to a significant drop in lvef from 52 % to 33 % ( rest to stress ) , reversible regional wall motion abnormality is also noted with significant increase of summed motion scores ( sms ) from 22 to 40 . the end - systolic volume ( esv ) is severely enlarged from 29 ml to 60 ml with a ratio of 2.07 ; however , the end - diastolic volume ( edv ) is modestly enlarged from 61 ml to 89 ml ( ratio : 1.45 ) . although tid has already been confirmed to be a highly specific marker of extensive and severe cad , tid might also be related to microvascular disease , which usually refers to the patients with chest pain but normal coronary angiograms ( cpnca ) . syndrome x , which was found to have stress - induced diffuse subendocardial hypoperfusion as evidenced on vasodilator - stress and rest cardiac mri . fig .7 shows the images of an 82 year - old female patient , who presented with typical angina pectoris and was referred for mps as a work - up of suspected cad . homogenous perfusion was noted on both stress and rest images , but she was still referred for invasive coronary angiography due to the appearance of remarkable tid on mps . this case was finally concluded as microvascular disease because no significant diameter stenosis was found in the epicardial coronary arteries on angiography . in order to avoid unnecessary invasive diagnostic procedure in , multi - slice ct coronary angiography might be an optimal choice of imaging modalities for cases of tid on mps with normal or near - normal perfusion . myocardial stunning , defined as prolonged global and / or regional myocardial dysfunction after stress - induced ischemia , has been well described on stress / rest gated mps . it might be manifested as transient post - stress decline of lvef or reversible regional wall motion abnormality on gated mps and were found to correlate with the severity of stress - induced perfusion defects . plenty of studies further demonstrated that stress - induced stunning shown on gated mps was correlated with severe and extensive cad . it should be noted that the manifestations of ischemic stunning might be different when using different kinds of radiotracers ( e.g. tl - 201 or tc - 99 m sestamibi ) or different types of stress ( e.g. exercise or vasodilator ) . the images show significant enlargement of the inner cavity of the lv on stress as compared to rest mps . in contrary to the tid shown on fig .6 , which has consistently enlargements for both inner and outer surfaces , the size of the lv based on epicardial borders is almost identical between stress and rest in the current case . the pathophysiological mechanism of tid in this case should be stress - induced diffuse subendocardial hypoperfusion , resulting in visually enlargement of lv cavity . gated spect myocardial perfusion imaging provides information on perfusion at the time of tracer injection and function during image acquisitions . although stress - induced myocardial stunning might persist for 30 to 240 minutes , or even more than 24 hours after stress , most of its effects resolve during the first 30 to 60 minutes . accordingly , the detection of stress - induced stunning on gated mps depends greatly on the time interval between the end of stress and start of image acquisition . image acquisition usually started 60 minutes after stress with the use of tc - 99 m sestamibi , but started within 5 - 10 minutes after stress with tl - 201 . thus , gated mps using tl - 201 as the radiotracer might be more sensitive for detecting stress - induced ischemic stunning . it is well - known that exercise - stress ( such as treadmill test ) used for mps may cause true myocardial ischemia and thus induce ischemic stunning in patients with cad during mps . in contrary , vasodilator - stress does not increase myocardial oxygen demand as much as exercise stress and is believed not to cause ischemia as often as exercise . using the diameter stenosis shown on invasive coronary angiography as the reference standard , hung et al . found that dropping of lvef more than 6 % after dipyridamole ( a commonly used vasodilator - stress agent ) stress was a highly specific indicator of high - grade coronary stenosis ( a positive predictive value of 90 % ) , but a sensitivity of only 35 % in addition to the incremental diagnostic value in severe cad , ischemic stunning shown on tl - 201 gated mps has also been found to be an independent prognostic factor of predicting major adverse cardiac event . although the perfusion images shown on mps are near normal , the functional images show significant stress - induced stunning , as manifested by both dropping of lvef and worsening of regional wall motion after vasodilator stress . this case indicates the incremental value of ischemic stunning in the detection of severe and extensive cad with gated mps . the images show mild to moderate hypokinesis involving apical - mid anterior wall , septum and inferior wall on stress images . on rest images , the anterior wall and septum are normokinetic , and apical inferior wall is mildly hypokinetic . worsening of regional wall motion after dipyridamole - stress is observed in apical mid anterior wall , septum and apical inferior wall . phase analysis for gated mps was first developed by chen et al . in 2005 for measuring lv dyssynchrony . previous studies have shown that quantitative indices given by phase analysis , such as phase standard deviation ( psd ) and phase histogram bandwidth ( phb ) , were correlative well with lv dyssynchrony measured by tissue doppler imaging , highly reproductive and repeatable , , and predictive of response to cardiac resynchronization therapy ( crt ) in heart failure patients . all of the above studies were done using tc - 99 m labeled radiotracers ( sestamibi or tetrofosmin ) . as we mentioned previously , gated mps with tc - 99 m tracers usually acquired data one hour or more post injection . therefore , a study using tc - 99 m sestamibi mps reported that the presence of even large reversible defects did not alter lv dyssynchrony from rest to stress . chen et al . first validated the performance of tl - 201 gated mps for phase analysis and found good correlation with tc - 99 m sestamibi . the same group further investigated whether stress - induced myocardial ischemia is associated with lv mechanical dyssynchrony . this study demonstrated that stress - induced myocardial ischemia caused dyssynchronous contraction in the ischemic region , deteriorating lv synchrony . normal myocardium had more synchronous contraction at stress , but scarred myocardium had no change .9 . the different dyssynchrony pattern between ischemic and normal myocardium at early post - stress may aid diagnosis coronary artery disease using tl - 201 gated mps . further study is warranted to assess the incremental value of stress - induced dyssynchrony over conventional assessment of tl - 201 gated spect mpi in the diagnosis of cad , especially in the settings of multi - vessel disease with balanced ischemia . improved lv synchrony is noted for normal myocardium . in the patient with myocardial infarction , no change in lv synchrony is noted in the infarcted area , but the global indices of lv dyssynchrony ( psd and phb ) improves due to better synchrony in areas with normal myocardium . mps has been an established imaging modality , which provides very useful diagnostic and prognostic information for patients with suspected or known cad . it has also been clinically accepted as the gatekeeper of further invasive procedures in the management of cad . however , its limitations to underestimate the severity and / or extent of myocardial ischemia in patients with multi - vessel disease should be noticed carefully . additional markers shown on mps , such as tid , ischemic stunning or worsening dyssynchrony caused by stress , are all useful to help reduce or avoid this rare but serious clinical setting .\noutput:\n" }, { "from": "agent", "value": "over the past decades , stress / rest myocardial perfusion spect ( mps ) has been utilized as a standard modality for the diagnosis , risk stratification and prognostic assessment of coronary artery disease ( cad ) . in addition to the perfusion information , mps can also provide functional information of the left ventricle , including volume , ejection fraction , wall motion and dyssynchrony . this article introduces the incremental value of these non - perfusion parameters as markers and prognosticators of cad ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we collected 21 pairs of edta whole blood and serum specimens from 21 patients with mers - cov after admission to the national medical center in seoul , south korea . mers - cov infection initially was diagnosed by the korea centers for disease control and prevention using respiratory specimens ( 11 ) . after admission , viral rna was extracted and eluted with a magna pure lc 2.0 automated nucleic acid extractor and magna pure lc total nucleic acid isolation kit ( both from roche diagnostics , mannheim , germany ) according to the manufacturer s instructions . specimen volumes were 100 l edta whole blood and 200 l serum , and elution volumes were 100 l for edta whole blood and 50 l for serum . one - step , real - time reverse transcription pcr ( rrt - pcr ) was performed for the 3 mers - cov gene regions ( upstream envelope [ upe ] , open reading frame [ orf ] 1a , and nucleocapsid ) with an agpath - id one - step rt - pcr kit ( applied biosystems , foster city , ca , usa ) and an abi7500 real - time pcr system ( applied biosystems ) . human ribonuclease ( rnase ) p was amplified in parallel for sample quality control ( 5,12,13 ) . in each test , the viral rna was considered detected when amplification before cutoff was observed from at least 2 different targets in mers - cov with pass of sample quality control . the robustness of rrt - pcr was demonstrated for qualitative concordance of positivity or negativity by using different types of specimens ( technical appendix table 1 ) . we calculated the viral copy concentration in the blood using standard curves constructed from the cycle threshold ( ct ) of serially diluted 10 copies / l of upe rna ( provided by the university of bonn medical center , bonn , germany ) . we assessed the relationships among clinical and molecular diagnostic factors with the ibm spss statistics program 22.0 ( spss inc . , chicago , il , usa ) . in each test , p 0.05 was considered statistically significant . the institutional review board of the national medical center approved this study ( h - 1508 - 057 - 002 ) . we assessed patient demographics , their clinical features , and disease outcomes ( tables 1 , 2 ; technical appendix table 2 ) . the time difference was an average of 1.5 days ( median 1 , range 05 days ) between when the initial diagnostic respiratory specimens and blood specimens were obtained . at admission , viral rna was detected in 6 ( 29 % ) of 21 edta whole blood and 6 ( 29 % ) of 21 serum samples from infected patients . two patients showed viral positivity in either specimen subtype of edta whole blood or serum ; therefore , the overall detection rate for mers - cov was 33 % ( 7/21 ) in blood . the concordance rate of viral assay was 90 % ( 19/21 ) between edta whole blood and serum specimens . blood virus concentration was 3,130 copies / ml edta whole blood ( range 2,08017,400 copies / ml ) , equivalent to a median upe ct of 37.55 , and 1,300 copies / ml serum ( range 49010,200 copies / ml , median upe ct 36.88 ) . * based on contact history . * ct , cycle threshold ; rrt - pcr , real - time reverse transcription pcr . blood viral rna positivity at admission was associated with fever 37.5 c on the sampling date ( p = 0.007 ) , requirement for mechanical ventilation during the following clinical course ( p = 0.003 ) and extracorporeal membrane oxygenation ( p = 0.025 ) , and patient death ( p = 0.025 , all by 2 - tailed fisher exact test ; figure ) . blood viral rna positivity was not associated with viral ct in the initial diagnostic lower respiratory specimens , or requirement of oxygen supplementation during the following clinical course . between the blood viral rna - positive and - negative groups , we found no differences in age , duration from symptom onset to diagnosis of mers - cov infection , or an invasive procedure before the specimens were obtained ( technical appendix table 3 ) . viral loads in the lower respiratory specimens at the initial confirmatory diagnosis showed no effect on patient survival ( figure ) . patient death was not associated with length of time from symptom onset to diagnosis of mers - cov infection ( technical appendix table 3 ) . differences in survival among middle east respiratory syndrome coronavirus infected patients , south korea , 2015 . a , b ) survival difference between the blood viral rna - positive ( solid line ) and - negative ( broken line ) groups . survival was defined as the time from initial confirmatory diagnosis to death before hospital discharge ( a ) ( kaplan - meier survival analysis , log rank p = 0.009 ; breslow p = 0.006 ) and as the time from symptom onset to death ( b ) ( kaplan - meier survival analysis , log rank p = 0.017 ; breslow p = 0.015 ) . c , d ) survival difference between the high respiratory viral load ( solid line ) and low respiratory viral load ( broken line ) groups . viral loads were classified into 2 groups : patients who harbored viral loads above the median load of patients and patients who harbored below . cycle threshold ( ct ) values were calculated for real - time reverse transcription pcrs targeting the upstream of envelope region ( c ) and open reading frame 1a region ( d ) ( kaplan - meier survival analysis , log rank p = 0.739 ; breslow p = 0.630 ) . our results showed that the detection rate of blood viral rna was low in the early phase of infection in patients with a confirmed diagnosis , similar to results from a previous study ( 14 ) . these findings contrasted with those of severe acute respiratory syndrome coronavirus infection ( 15 ) . therefore , in the case of mers - cov infection , blood does not have the highest diagnostic yield for the initial confirmatory diagnosis . a proportion of mers - cov isolates in the 2015 korea outbreak harbored a ct substitution in the third nucleotide of the orf1a primer binding site ( genbank accession nos . kt374052374055 ) . this mismatch may partially contribute to the insensitivity of orf1a assay observed in this study . blood viral rna has been detected in a few case reports of mers - cov fatalities ( 810 ) . our data of 42 specimens from cross - sectional time points focusing on early viremia showed that blood viral rna was present in a subpopulation of patients and that these patients had significantly poorer prognoses , as demonstrated by the need for more frequent mechanical ventilation and the increased risk for death . further large studies using serial daily specimens that are collected throughout the admission period both upper and lower respiratory specimens and paired measurement of viral rna and antibody in blood might help overcome the limitation of the current study , which included relatively small numbers of deceased patients ( 24 % [ 5/21 ] ) . our data showed a detection rate of 33 % for viral rna in blood at initial diagnosis , which was insufficient for initial confirmatory diagnosis . blood viral rna at the early phase was related to a worse clinical course in infected patients and might be a good prognostic indicator of severe outcome . sensitivity , reproducibility , and inhibitory effect among different specimen types for the middle ease respiratory syndrome coronavirus ( mers - cov ) real - time reverse transcription pcr ; viral rna analyses of mers - cov infected patients ; and statistical relationships among clinical and molecular diagnostic factors .\noutput:\n" }, { "from": "agent", "value": "we evaluated the diagnostic and clinical usefulness of blood specimens to detect middle east respiratory syndrome coronavirus infection in 21 patients from the 2015 outbreak in south korea . viral rna was detected in blood from 33 % of patients at initial diagnosis , and the detection preceded a worse clinical course ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: osteoporosis is a condition of skeletal fragility characterised by decreased bone mass and microarchitectural deterioration of bone tissue , with a consequent increase in risk of fracture . osteoporosis is a worldwide health issue , with a high prevalence of disease not only in western countries but also in asia and latin america . women were found to have a higher risk of getting osteoporosis than men with the ratio of 1.6 : 1 . postmenopausal osteoporosis stems from the cessation of ovarian function at menopause which heightens and prolongs the rapid phase of bone loss characteristic of the early postmenopausal period . it is associated with significant morbidity , mortality , reduction in quality of life , and increasing health care . about 1 in 3 women aged more than 50 years experienced an osteoporotic fracture in their lifetime . in women , osteoporosis and fractures mainly occur as a consequence of decrease in estrogen after menopause and result from an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts , leading to a net bone loss with each remodelling cycle . estrogen deficiency also augments erosion depth by extending the resorption phase of remodelling cycle through increased osteoclast life span due to its reduced apoptosis . estrogen replacement therapy ( ert ) and combination hormone replacement therapy ( chrt ) are two medication therapies often prescribed to supplement the decreased levels of hormones in postmenopausal women . research by cauley et al . showed that hormone replacement therapy ( hrt ) can significantly improve bone mineral density ( bmd ) and reduce the risk for fractures of the vertebral spine , lower arm / waist and hip areas regardless of previous history , age , familial history , smoking , alcohol status , bmd , or fracture risk rates . the women 's health initiative ( whi ) suggests , however , that the long - term risks of hrt outweigh the benefits . it is associated with coronary heart disease , breast cancer , and stroke . in most countries , hrt is only recommended for climacteric symptoms , at a dose as small as possible and for a limited period of time . thus , hrt is no longer recommended as a firstline treatment for the prevention and treatment of osteoporosis . thus , the ultimate goal of treating women with postmenopausal osteoporosis is to identify compounds which not only reduce the risk of fracture but also have minimal side effects . despite the myriad of potential health benefits of the marine bioactives , efforts are needed to expand the marine based drug discovery to include osteoporosis disorders , which need extensive and urgent attention in terms of new therapies . euchelus asper , a marine mollusc that belongs to class gastropoda , is a shell - oriented animal . it is commonly seen along the entire west coast and extends up to the south east coast in india . organic matrix from molluscan shells has the potential to regulate calcium carbonate deposition and crystallization . biomineralization is one essential element in living organisms to protect themselves against predators and to form multicellular aggregates , for example , during bacterial biofilm formation , or in multicellular organisms , for example , in animals and plants . the organic matrix of the mollusc directs crystallization and the deposition and rate of crystals are also controlled by hormones produced by the mollusc . earlier studies by our group have shown that ether soluble fraction of euchelus asper ( eae ) exhibited immunosuppressive activity in vivo by plaque forming assay . in the present studywe have tried to investigate the antiosteoporotic effect of methanol extract of euchelus asper ( eame ) . the organism exposed during the low tide was collected from the rocky shore of khar danda , mumbai , maharashtra , india . itwas deshelled and the body mass was cold - percolated in methanol for 3 - 4 days . the resulting methanol extract was filtered and the residual animal mass was again immersed in fresh methanol . the filtered extracts were pooled and concentrated under reduced pressure and crude gummy methanol extract was obtained with a yield of 1.25 % . female swiss albino mice of 1822 g maintained at the animal house of actrec were used for the study . this study was approved by institutional animal ethics committee ( iaec ) of actrec , tata memorial centre , mumbai , india . the mice were randomly divided into 7 groups , consisting of 6 animals in each group . group c. bilaterally ovariectomized control treated with estradiol - 2 mg / kg body weight ( positive control ) . group d. bilaterally ovariectomized control treated with eame 25 mg / kg body weight . group e. bilaterally ovariectomized control treated with eame 50 mg / kg body weight . group f. bilaterally ovariectomized control treated with eame 100 mg / kg body weight . group g. bilaterally ovariectomized control treated with eame 200 mg / kg body weight . all mice were bilaterally ovariectomized after anesthetizing with ketamine + xylazine . after 7 days of recovery from surgical convalescence , animals of groups d , e , f , and g were administered orally through stomach tube with eame , 25 , 50 , 100 , and 200 mg / kg body weight of eame , respectively . the vehicle or extract was dissolved in sterilized water and was administered daily for 4 weeks . animals in the control groups a and b received water ( vehicle control ) and of group c received estradiol ( positive control ) . the body weight of the animals was recorded weekly during the experimental period . on completion of the experimental period , the animals were sacrificed under deep anaesthesia on the scheduled date and fresh weight of uteri was recorded . blood was collected from retroorbital region and centrifuged at 1500 g for 20 min . serum alkaline phosphatase ( alp ) and acid phosphatase activity ( acp ) were estimated spectrophotometrically at 510 nm using span diagnostic kit , span diagnostic ltd . , the tibia and uterus were harvested rapidly and fixed with bouin 's solution for 2 h , which was followed by decalcification in 5 % nitric acid for tibia , dehydration in alcohol , clearing in xylene , and finally embedding in paraffin for further tissue section and histological staining . to measure bone dna content , the metaphyseal tissues of the femur bonewere shaken with 4.0 ml of ice - cold 0.1 m naoh solution for 24 h after the homogenization of the bone tissues . after alkaline extraction , the samples were centrifuged at 10000 g for 5 min and the supernatant was collected . dna content in the supernatant was determined using the method of diphenylamine reaction and expressed as the amount of dna mg / g of wet weight of bone tissue . spleens were removed from swiss albino mice ( 1822 g ) under aseptic condition and splenocytes were isolated . mice splenocytes were plated in 96 well plates at a concentration of 1.510 cells / well . eame was dissolved in dmso and dilutions prepared in rpmi - 1640 supplemented with 10 % fbs and cells were incubated for 72 hr . in 5 % co2 at 37c . the general proliferation of lymphocytes was noted by reduction of the yellow dye 3 - ( 4,5 - dimethythiazol -2-yl ) -2,5-diphenyl tetrazolium bromide ( mtt ) to form a blue product . after 4 hr . of incubation , the formazan product of mtt ( sigma - aldrich , st . louis , mo , usa ) reduction was dissolved in dmso , and absorbance was read using multiplate reader . the drug effect was quantified as percentage of control absorbance of the reduced dye at 540 nm . cytotoxicity of eame was checked within the concentration range of 0.97500 g / ml . bone marrow cells were isolated from whole bone marrow of 4 - to 6 - week - old mice . both the ends of bone of the femur were cut - off and the marrow cavity was flushed with - minimum essential medium ( - mem , sigma - aldrich , st . the marrow cells obtained were washed with - mem and cultured in the same medium containing fetal bovine serum ( fbs ) at 110 cells / ml in 24 well plates , in the presence of 10 ng / ml m - csf at 37c in 5 % co2 . after 24 h , the nonadherent cells were further cultured on coverslips in a 35 mm culture dishes at a concentration of 110 cells / ml and incubated with 30 ng / ml macrophage - colony stimulating factor ( m - csf ) ( sigma - aldrich , st . louis , mo , usa ) and 30 ng / ml receptor activator of nuclear factor kappa - b ligand ( rankl ) ( sigma - aldrich , st . one half of the old medium was replaced with fresh medium on third and sixth day . extract was added to the culture medium at the beginning of the culture and at the time of medium change at various concentrations from 200 g / ml to 12.5 g / ml . after 7 days in culture , adherent cells were fixed and trap staining was performed using trap solution . the fixed cells were then incubated for 1 hr . at room temperature in acetate buffer containing 10 mm sodium tartrate and naphthol as - mx phosphate ( sigma - aldrich , st . louis , mo , usa ) as a substrate and fast red violet lb salt ( sigma - aldrich , st . trap ( + ) multinucleated cells containing three or more nuclei were counted as osteoclast - like cells . data are presented as mean sem and analyzed by student 's t - test or one - way anova followed by tukey 's test . after 4 weeks of treatment final body weights of all groups were not significantly different between the groups ( data not shown ) . this uterine atrophy was caused by the depletion of the estrogen supplied by the ovary , thus indicating that the ovaries had been completely removed by the surgical procedure . the ovariectomy - induced atrophy of the uterus was partially prevented by the estradiol treatment . eame at the doses of 200 , 100 , and 50 mg / kg elicited uterotrophic effect by reducing the atrophy of the uterus induced by ovariectomy ( table 1 ) . ovx mice had a high release of serum calcium in the blood as compared to sham group ( p 0.01 ) . this release of calcium in ovx mice was suppressed by eame 100 , 50 , and 25 mg / kg treatment with significance value of p 0.01 . eame 200 mg / kg treated group showed an increase in serum calcium as compared to ovx group ( table 1 ) . alp and acp are bone formation and bone resorption markers , respectively , and can be estimated to investigate the bone turnover rate . alp and acp values were recorded after the first and fourth week of oral administration of eame . alp and acp values after first week of oral administration were found to be random ( figure 1 ( a ) ) . at the end of the experiment ( after four weeks of oral administration ) , the alp activity for ovx was higher than the sham group ( p 0.001 ) . treatment with eame 200 , 100 , 50 ( p 0.001 ) , and 25 mg / kg ( p 0.01 ) could significantly reduce the increased alp levels , whereas eame 200 mg / kg ( p 0.01 ) , 100 mg / kg ( p 0.01 ) , 50 mg / kg ( p 0.001 ) , and 25 mg / kg ( p 0.01 ) treated groups also revealed reduced acp values as compared to ovx group . estradiol treatment could also effectively decrease the elevated alp and acp activity ( figure 1 ( b ) ) . the histological study of tibia revealed sparse , disrupted trabecular bone and empty bone marrow spaces in the ovx mice of the eame treated group . the restoration of the trabecular network with less intertrabecular spaces was observed in eame 200 mg / kg , 100 mg / kg , and 50 mg / kg . estradiol treated group also showed some improvement in the trabecular formation ( figure 2 ) . ovx group showed decrease in the number of uterine glands which appeared atrophied . eame 200 mg / kg , eame 100 mg / kg , andeame treatment could maintain the intactness of the stromal tissue similar to sham control group . in case of estradiol treated group , uterine glands were enlarged and atrophied and their epithelium showed distortion in the estradiol treated group . eame treated groups showed no such distortion in the uterine glands similar to that of sham control group ( figure 3 ) . bone growth can also be studied by investigating its dna content which also reveals the number of bone cells including osteoclasts , osteoblasts , and osteocytes in bone cells . the dna content in the metaphyseal tissue was increased by eame treatment ( figure 4 ) . eame 200 mg / kg ( p 0.05 ) , 100 mg / kg ( p 0.05 ) , and 50 mg / kg ( p 0.05 ) increased the metaphyseal dna content as compared to ovx . sham control also increased the metaphyseal dna content but was not found to be significant . in order to select the concentration for the bioassays , cytotoxicity of extract was determined on mice splenocytes . as shown in figure 5 , percentage survival of the cells treated with eame was found to be more than the control revealing no cytotoxic effect of eame on the cells . eame did not show any cytotoxicity from the concentration range of 500 g / ml to 0.97 g / ml . anticlastogenic data of eame is presented in figure 6 which shows that eame suppressed the rankl - mediated osteoclast formation significantly at concentration of 50 g / ml ( p 0.001 ) and 25 and 100 g / ml ( p 0.01 ) . postmenopausal osteoporosis is an estrogen - deficient state characterized by bone fragility , as the balance between bone resorption and bone formation shifts towards increased levels of bone resorption . the safety of hrt is under question due to its compliance to serious side effects . hence , it is plausible and logical to look for substances that have fewer side effects than estradiol in the hope of identifying some natural nutritional supplements that reduce menopausal symptoms and , perhaps , benefit bone without the adverse effects associated with hrt . the ovariectomised ( ovx ) mice or rat models mimic changes in bone metabolism observed in postmenopausal osteoporosis and is considered as a gold standard for preclinical model for postmenopausal bone loss . ovariectomy in the mice results in an increase in bone turnover rate resulting in cancellous osteopenia . estradiol was used as the positive control in our study , because it is proved to have bone conserving effects and is endowed with good anabolic activities on bone in vivo . in the present studywe have attempted to investigate the effect of oral administration of the methanol extract of euchelus asper on estrogen deficiency induced bone loss . the uterotrophic effect of estrogenic substances results in an increase in the uterine wet weight , which is an end point utilized in the standard uterotrophic assay . a marked atrophy of the uterus has been used as evidence of the success of ovariectomy , because estrogen directly influences uterine weight . the uterine weight which was decreased by ovariectomywas maintained by eame supplementation as compared to sham suggesting a uterotrophic activity of the compounds present in eame . oral administration of eame suppressed the loss of calcium in serum indicating its role in physiological calcium level . bone turnover markers are clinically reliable to predict imbalance between bone formation and bone resorption and , therefore , predict the rate of bone loss . alkaline phosphatase ( alp ) is a key enzyme for bone calcification and provides an index of cell differentiation for bone formation . acid phosphatase ( acp ) , an important marker of bone resorption , positively correlated with histomorphometric indice of bone resorption . serum concentration of both alp and acp was significantly greater in the ovariectomised control mice suggesting a high bone turnover rate , which were reduced by the administration of eame . postmenopausal bone loss is due to rapid bone metabolism in which bone remodeling is high . menopause in women significantly increases bone resorption over formation due to low levels of estrogens thus inducing accelerated bone loss . in the present studyalso ovariectomy has shown high remodeling by increase in bone turnover markers which was reduced by eame supplementation . increased bone remodelling is associated with a transient loss of bone , increased porosity in the subchondral region , and reduced density . the tibia of the ovx group of mice showed porosis and an empty bone marrow with less trabecular bone at the proximal head of tibia . however , remodeling lines were observed after administrating the ovariectomised mice with eame for 4 weeks similar to the sham control group . histological assessment suggested that eame induced the formation of new cancellous bone in the proximal tibial region to an equivalent extent as seen in the sham control . , a marine organism belonging to phylum cnidaria , showed protective effects on both trabecular and cortical bone of the humerus in ovariectomised mice model . norzoanthamine also accelerates the formation of a collagen - hydroxyapatite composite in bone which helps in bone formation , and hence it can be a promising drug candidate for osteoporosis treatment and prevention . the histological assessment of uterine epithelium of the ovx group showed many evident evaginations and hyperplasia of the epithelium . similar results were reported by a previous study where treatment with ethinyl estradiol in ovariectomised mice produced significant increase in endometrial thickness , endometrial epithelial height , and the number of endometrial glands . but eame did not show any estrogenic effect as seen by estradiol treatment . despite having similar effects on bonesimilar studies were conducted by xie et al . for their plant extract of herba epimedii , which also produced a beneficial effect on bone without inducing potentially harmful effect on reproductive organs . dna content in the bone tissues is an index of bone growth and the number of bone cells . the intake of supplement containing zinc and the combination of - cryptoxanthin ( 10 m ) plus zinc ( 10 m ) was found to cause a remarkable increase in alkaline phosphatase activity and dna content in the diaphyseal and metaphyseal tissues in rats . yamaguchi et al . in their studies showed the synergestic effect of zinc with - cryptoxanthin on bone components by studying its effect on metaphyseal dna content . in the present study , bone resorption by activated osteoclasts with subsequent deposition of a new matrix by osteoblasts causes the formation of bone structure and bone remodeling . imbalance between bone formation and bone resorption is the key pathophysiological event in many metabolic bone disorders in adult humans , including osteoporosis , a result of bone loss . thus it is accordingly thought that the medicines which improve the activity of osteoblast to facilitate osteogenesis and inhibit the activity of osteoclast to delay osteolysis are ideal therapeutic agents in osteoporosis . we further aimed to investigate whether this effect is reflected on the osteoclast by showing the antiosteoclastogenesis of the extract . the osteoclasts were cultured from mice bone marrow cells in the presence of rankl , m - csf , and the extracts . to discover novel inhibitors from eame we did screening of osteoclast by staining trap activity which is involved in the bone resorption process of mature osteoclast . trap is considered a histochemical marker of osteoclasts and is highly expressed in osteoclasts in normal condition . therefore , the development of drugs that act to regulate osteoclast formation is important to prevent bone disease . our earlier investigation has shown that mollusc turbo brunneus inhibits the bone resorption by acting on t cells to reduce the tnf secretion which is responsible for osteoclast maturation and also revealed a potent antiosteoclastogenic activity . in conclusion , the present study demonstrated that eame could reduce the rapid bone loss occurring in ovariectomised mice leading to an imbalanced bone metabolism using bilaterally ovariectomised mice model . our evidence clearly demonstrates that euchelus asper could be considered as a natural alternative to hormone replacement therapy for the prevention and treatment of bone loss in postmenopausal women . further research is required to elucidate and identify the bioactive compound present in eame for its antiresorptive effect .\noutput:\n" }, { "from": "agent", "value": "marine molluscs are widely distributed throughout the world and many bioactive compounds exhibiting antiviral , antitumor , antileukemic , and antibacterial activity have been reported worldwide . the present study was designed to investigate the beneficial effect of methanol extract of euchelus asper ( eame ) on estrogen deficiency induced osteoporosis in ovariectomised mice model . forty - two female swiss albino mice were randomly assigned into sham operated ( sham ) group and six ovariectomised ( ovx ) subgroups such as ovx with vehicle ( ovx ) ; ovx with estradiol ( 2 mg / kg / day ) ; ovx with eame of graded doses ( 25 , 50 , 100 , and 200 mg / kg / day ) . bone turnover markers like serum alkaline phosphatase ( alp ) , serum acid phosphatase ( acp ) , serum calcium , and histological investigations of tibia and uterus were analysed . metaphyseal dna content of the femur bone was also studied . antiosteoclastogenic activity of eame was examined . administration of eame was able to reduce the increased bone turnover markers in the ovariectomised mice . histomorphometric analysis revealed an increase in bone trabeculation and restoration of trabecular separation by eame treatment . metaphyseal dna content of the femur of the ovx mice was increased by eame administration . eame also showed a potent antiosteoclastogenic behaviour . thus , the present study reveals that eame was able to successfully reduce the estrogen deficiency induced bone loss ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the online version of this article ( doi : 10.1007 / s40121 - 014 - 0045 - 7 ) contains supplementary material , which is available to authorized users . good s syndrome is a relatively rare immunodeficiency condition that presents in the fourth or fifth decade of life and is defined by hypogammaglobulinemia in the setting of a thymoma . the humoral defect may be severe enough to cause an absence in b cells , with a consequent recurrence of sinopulmonary disease , chronic non - infectious diarrhea , and opportunistic infections . the prognosis in patients with good s syndrome appears to be worse than in those with x - linked agammaglobulinemia ( xla ) and common variable immune deficiency ( cvid ) . in a caseseries of 240 patients , the 5 - year survival rate was almost 100 % for patients with xla and cvid , compared to 70 % for patients with good s syndrome . the 10 - year survival rate dropped to 33 % in good s syndrome patients , compared to 95 % for patients with xla and cvid . morbidity and mortality in good s syndrome is attributable to secondary processes such as infections , autoimmunity and hematological dysfunction , rather than the thymoma itself . there have only been three cases of good s syndrome associated with mycobacterium , and only one case with a cavitary lesion in the lungs . we present here a unique case of good s syndrome with a non - mycobacterial cavitary lesion . a 56 - year - old ethiopian male immigrant was admitted with persistent fever and chills , cough , night sweats , and weight loss . he had a past medical history significant for a type a thymoma that was resected 3 years prior to admission . an outpatient pulmonologist who had seen him for suspected tuberculosis referred him to the inpatient medicine unit following a computed tomography ( ct ) scan of the chest that revealed a 3.5 cm right hilar region mass . there were also two additional smaller adjacent nodules in the right lower lobes , and scattered areas of tree and bud nodularity . the patient was subsequently admitted to ronald reagan ucla medical center and placed on respiratory isolation . here , he reported a history of fatigue and dyspnea on exertion , as well as recurrent sinopulmonary infections that intermittently responded to antibiotics . these infections often recurred in the setting of irritable bowel syndrome d ( ibs - d ) symptoms , hallmarked by diarrhea . at the time of admission , he had a low - grade fever with otherwise normal vital signs and oxygen saturation on room air . blood tests were significant for an absolute lymphocyte count of 1,000 cells / l , and hemoglobin of 11.7 g / dl . a chest ct scan on admission revealed an irregular , cavitating soft - tissue right hilar mass involving the posterior segment of the right upper lobe and superior segment of the right lower lobe . in addition , there were focal areas of mucous impaction and bronchiectasis with multiple diffuse scattered clusters of bronchocentric micronodules , many in a tree - in - bud nodularity ( fig . 1 ) . fig .1 computed tomography ( ct ) scan of the chest with a right hilar region mass , mucous impaction and bronchiectasis computed tomography ( ct ) scan of the chest with a right hilar region mass , mucous impaction and bronchiectasis cultures of blood , sputum and urine were negative for an extensive workup that included human immunodeficiency virus ( hiv ) , cytomegalovirus ( cmv ) , acid - fast bacillus , histoplasma , aspergillus and coccidioidomycosis . finally , a biopsy of the cavitary lesion of the lung showed ulceration with acute and chronic inflammation . grocott s methenamine silver ( gms ) staining was negative for fungal organisms , and there was no evidence of malignancy . on the second day of hospitalization , inducedsputum was positive for pneumocystis jiroveci and moraxella catarrhalis . given the history of recurrent pneumonia , lymphopenia and an opportunistic infection in the setting of a hiv negative patient , a more thorough immunologic workup was performed . as shown in table 1 , low levels of cd3 ( 540 / cmm ) and cd4 ( 250 / cmm ) t cells were found , while cd8 ( 264 / cmm ) , and cd16 & 56 ( 93 / cmm ) were normal . the b cell lineage was profoundly deficient , starting with cd19 ( 1 / cmm ) , and carried through with immunoglobulin m ( igm ) ( 5 mg / dl ) , iga ( 20 mg / dl ) , and igg ( 176 mg / dl ) ; he showed no antibody response to any of the 14 pneumococcal serotypes examined . furthermore , a lymphocyte proliferation assay demonstrated a significantly decreased response to tetanus and candida , as compared to a normal control.table 1lymphocyte and immunoglobulin enumerationt / b / nk cell subsetsabsolute count ( normal range ) percentage ( normal range ) cd3540 / cmm ( 8412,402 ) 86 % ( 5986 ) cd4250 / cmm ( 3551,426 ) 42 % ( 2962 ) cd8264 / cmm ( 2551,090 ) 45 % ( 1641 ) cd191 / cmm ( 10590 ) 1 % ( 725 ) cd16 & 56 ( nk cells ) 93 / cmm ( 71477 ) 15 % ( 419 ) immunoglobulinslevel ( normal range ) iga20 mg / dl ( 80400 ) igg176 mg / dl ( 6901,660 ) igm 5 mg / dl ( 37318 ) cd cluster of differentiation , ig immunoglobulin , nk natural killer lymphocyte and immunoglobulin enumeration cd cluster of differentiation , ig immunoglobulin , nk natural killer the patient was subsequently treated for pneumonia with sulfamethoxazole / trimethoprim double strength for 3 weeks followed by sulfamethoxazole / trimethoprim single strength for prophylaxis . he was also started on monthly intravenous immunoglobulin ( ivig ) replacement , which was continued after discharge . over 6 months following dischargethe patient remains free of hospitalization , reporting a reversal of his dyspnea , and a drastic improvement in his quality of life . he continues to be monitored for anemia , as there have been reported cases of good s syndrome with pure red cell aplasia . the 2005 practice parameters define good s syndrome as a subset of cvid ; however , the reduced number of peripheral b cells seen in good s syndrome is not a feature of cvid , where only impairment in b cell maturation is usually observed . however , genetic analysis has begun to elucidate the etiology of good s syndrome , which , like cvid , appears to affect proteins involved in the proliferation and differentiation of b cells . in a systematic review of 152 patients with good s syndrome ,42 % of patients were diagnosed with thymoma prior to being diagnosed with hypogammaglobulinemia , infection or diarrhea , while in 38 % of patients the diagnoses were made almost simultaneouslysince 10 % of patients diagnosed with a thymoma continue to develop hypogammaglobulinemia , an immunologic workup at regular intervals can be very helpful in preventing opportunistic infections . additionally , patients with hypogammaglobulinemia should be screened for thymoma , as 10 % will continue to present with a thymoma . good s syndrome shares many features with cvid , but unlike the latter and the more serious xla , it carries a much worse prognosis . aside from the additional involvement of thymic dysfunction , one of the reasons for inferior outcomes is the greater delay in diagnosis . in contrast to other humoral immune defects , patients with this syndrome can develop opportunistic infections , and the prognosis appears less favorable compared with xla or cvid . immunological workup , including t cell subsets , b cells and quantitative immunoglobulins , should be considered as part of the routine diagnostic evaluation in patients with a thymoma and recurrent infections . it is important to note that good s syndrome may progress even after thymectomy and corticosteroid treatment . however , early recognition and treatment with antibiotics or immunoglobulin replacement can change the natural course of this rare condition , and prove to be successful in keeping the patient symptom free . this article is distributed under the terms of the creative commons attribution noncommercial license which permits any noncommercial use , distribution , and reproduction in any medium , provided the original author ( s ) and the source are credited .\noutput:\n" }, { "from": "agent", "value": "good s syndrome is a relatively rare immunodeficiency condition that presents in the fourth or fifth decade of life and is defined by hypogammaglobulinemia in the setting of a thymoma . the humoral defect may be severe enough to cause an absence in b cells , with a consequent recurrence of sinopulmonary disease , chronic non - infectious diarrhea and opportunistic infections . the prognosis in patients with good s syndrome appears to be worse than in those with x - linked agammaglobulinemia ( xla ) and common variable immune deficiency ( cvid ) . there have only been three cases of good s syndrome associated with mycobacterium , and only one case with a cavitary lesion in the lungs . we present here a unique case of good s syndrome with a non - mycobacterial cavitary lesion.electronic supplementary materialthe online version of this article ( doi : 10.1007 / s40121 - 014 - 0045 - 7 ) contains supplementary material , which is available to authorized users ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: hemolytic uremic syndrome ( hus ) is a clinical state characterized by microangiopathic hemolytic anemia , thrombocytopenia and acute renal failure . however , it has been associated with bacterial ( shigella , salmonella , e. coli , s. pneumoniae ) , bartonella , and viral ( coxsackie , echo , influenza , varicella , epstein - barr ) infections and with endotoxemia . recently we experienced a case of hemolytic uremic syndrome in a 16 - year - old boy who was in the acute phase of epstein - barr virus ( ebv ) infection . he had typical manifestations of hus , including pallor , malaise , edema , epistaxis , anuria , hematuria , azotemia and hypertension , as well as its prodrome such as bloody diarrhea , vomiting and mild fever . he also had manifestations of ebv infection including fever , skin rash , cervical lymphadenopathy , splenomegaly and positive immunoglobulin m ( igm ) - ebv antibody and ebv nuclear antigen ( ebna ) . he recovered by supportive care , including hemodialysis , plasmapheresis , antihypertensive medication and aspirin . a 16 - year - old boy had been in good health until june 21 , 1996 , when he finished a trip . on the next day , june 22 , he developed bloody diarrhea with diffuse abdominal pain and was treated conservatively at a local clinic . a few days later , he developed oliguria , hematuria and acute renal failure with anemia and thrombocytopenia . he had a transfusion and underwent hemodialysis twice , and then was referred to our hospital on july 4 , 1996 . the patient had no history of childhood illness and his familly history revealed no specific illnesses . on admission day , he had a mild fever , malaise , diffuse abdominal pain , chest discomfort , anuria , gross hematuria and epistaxis . on examination , his vital signs were as follows : blood pressure , 180/110 mmhg ; pulse rate , 80 beats per minute and regular ; respirations , 20 per minute ; temperature 37.2 c . he had a skin rash over his entire body ( scarlatiniform and petechial ) ( fig . 1 , 2 ) , g / l , the white blood cell count ( wbc ) was 7.910 cells / l ( polymorphoneutrophil 0.88 , lymphocyte 0.06 , monocyte 0.03 ) and the platelet count was 4010 / l . other values were as follows : blood urea nitrogen ( bun ) , 21.1 mmol / l ; serum creatinine , 1,001 mol / l ; serum aspartate aminotransferase ( ast ) , 1.01 kat / l ; and serum alanine aminotransferase ( alt ) , 0.33 kat / l . urinalysis showed albumin 3 + , 1 to 4 wbc and many rbc per high power field , and bile 2 + . the blood chemistry showed the following results : lactate dehydrogenase ( ldh ) , 22.3 kat / l ; serum total protein , 52 g / l ; serum albumin , 33g / l , calcium , 2.00 mmol / l , phosphorus , 2.19 mmol / l , total bilirubin , 11.9 mol / l ; peripheral blood smear showed anisocytosis , polychromatosis and schizocytosis which suggested hemolytic anemia . at a local clinic , prothrombin time ( pt ) was 26.1 sec , activated partial thromboplastin time ( aptt ) was 150 sec , fibrinogen was 2.3 upon admission to our hospital , pt was 13.7 sec ( 79 % ) , aptt was 29 sec , fibrinogen was 3.5 g / l , fdp was 80 mg / l and d - dimer test was positive . the cytomegalovirus ( cmv ) antibody , rubella antibody , hiv antibody , hantan virus antibody , leptospira antibody , and rhickettsia antibody were all negative . eighteen days after this result , early antigen ( ea ) - igg antibody was negative and heterophil antibody had a low titer of 1:14 , but the epstein - barr nuclear antigen ( ebna ) and ebv - igg antibody were positive . on his chest x - ray , the size of both kidneys was about 12 cm , the cortical echogenecity of the kidney was increased and there were splenomegaly and ascites . the electrocardiogram showed myocardial ischemia and there was a moderate degree of pericardial effusion on cardiac echocardiography . on the second day in hospital , therapy with hemodialysis and antihypertensives had been commenced . on the 3rd day , g / l , bun was 24.2 mmol / l , serum creatinine was 1,238 mol / l , platelet count was 5010 / l , urine ouput was below 50 ml / day and aspirin ( 100 mg / day ) therapy was started . from the 7th day , plasma exchange using 10 units of fresh frozen plasma was done five times on alternate days . on the 11th day , urine output was increased to more than 1,000 ml per day . on the 15th day , bun , serum creatinine and ldh were decreased to 11.0 mmol / l , 406 mol / l , and 2.55 kat / l , respectively , and gross hematuria disappeared . on the 17th dayprior to the patient s discharge , on the 29th day , renal function had markedly improved ; bun was 6.0 mol / l ; creatinine clearance , 0.86 ml / s ; urine protein , 1.0 g / d ; on urinalysis albumin ( ) , wbc 0 to 1 , and rbc 5 to 9 per high power field . other values had also improved ; the hemoglobin level , 101 g / l ; reticulocyte , 0.001 ; platelet count , 19010 / l ; total bilirubin , 5.1 mol / l ; ast , 0.31 kat / l ; alt , 0.17 kat / l ; blood pressure was 140/90 mmhg ( fig . this patient recovered by hemodialysis , plasmapheresis , antihypertensive medication and aspirin , and was treated with an antiplatelet agent after discharge . , it has been known that ebv can develop into thrombocytopenia with hus during the convalescent phase as an unusual manifestation . in this case , the patient had typical manifestations of hemolytic uremic syndrome , including pallor , malaise , edema , epistaxis , anuria , gross hematuria , proteinuria , azotemia and hypertension , as well as its prodrome such as bloody diarrhea , vomiting and mild fever . he showed the following signs : ( 1 ) microangiopathic hemolytic anemia ( anemia , schizocyte in peripheral blood smear , and increased reticulocyte count and ldh ) , ( 2 ) renal involvement ( increased bun and creatinine , hematuria , proteinuria , waxy cast in follow - up urinalysis , anuria for 12 days ) and ( 3 ) thrombocytopenia . autoimmune hemolytic anemia in infectious mononucleosis occurs rarely and it usually shows a positive coombs test . in this case , the coombs test was negative , so it was concluded that hemolytic anemia in this case was not due to infectious mononucleosis but a manifestation of hus . in infectious mononucleosis , mild thrombocytopenia is frequently found , but more marked thrombocytopenia with peripheral destruction occurs occasionally , and antiplatelet antibodies have been found in some of the cases . in this case , antiplatelet antibody was negative and thrombocytopenia was moderate , so it was also considered that thrombocytopenia was not due to infectious mononucleosis itself but due to hus associated with ebv . the decreased igg levels and elevated iga and igm levelshave been shown during the acute phase of hus and , in this case , a decreased igg level was present , dic was observed in 3 out of 22 cases of hus with acute renal failure . in another report , out of 14 children with hus that followed acute dysentery , dictherefore , it was suggested that dic may have a role in the pathogenesis of hus associated with acute dysentery . however , bukowski reported that less than 10 percent of cases reviewed retrospectively had fibrinogen levels depressed under 1.5 g / l . in our case , the patient had dic transiently , but the fibrinogen level was 2.3 infectious mononucleosis is an acute viral infection usually characterized by fever , sore throat , lymphadenopathy , splenic enlargement and abnormal lymphocytes in the peripheral blood . in our case , there was no lymphocytosis and the test of heterophil antibody was negative . however , fever , cervical lymphadenopathy , splenomegaly , periorbital edema , skin rash , mild elevated transaminase , igm - ebv antibody and ebna were present , representing the acute phase of infectious mononucleosis in this case . there was a difference in the time of the development of hus , as compared with the case reported in 1974 in which hus had developed in the convalescent phase of infectious mononucleosis . in 5 percent of patients , a macular , petechial , scarlatiniform , urticarial or erythema multiforme - like rash may appear . in this case , a petechial and scarlatiniform skin rash appeared . the elevation of transaminase appears in 20 to 40 percent of patients , and clinical jaundice is present in 5 percent of patients with infectious mononucleosis . in this case , jaundice did not appear . the transient abnormalities of electrocardiography and cardiac echocardiography in this patient ( myocardial ischemia and a moderate degree of pericardial effusion ) were considered as complications of infectious mononucleosis . the renal involvement of infectious mononucleosis may appear as hematuria , proteinuria , nephritis , hemoglobinuria or nephrotic syndrome . , renal failure appeared in 1.6 percent of infectious mononucleosis and generally occurred as interstitial nephritis , histologically . the mechanism of renal involvement is probably multifactorial and includes both a direct viral cytopathic effect and other factors including hemolysis , hyperuricemia , and nephrotoxic drugs . in some reports , infectious mononucleosis associated with renal failure and rhabdomyolysis was reported . however , to our knowledge , infectious mononucleosis associated with renal failure and hus has not been reported since 1974 . although we do not know the pathogenesis of hus in ebv infection , it is not possible to exclude a coexisting viral infection as the cause for the hus because the stool culture for e. coli , shigella etc . thus , we present this case with a review of the literature as the second report of hus associated with ebv infection and suggest that ebv can be associated with hus in the acute phase .\noutput:\n" }, { "from": "agent", "value": "the precise etiology of hemolytic uremic syndrome ( hus ) is unknown . however , it has been associated with bacterial ( shigella , salmonella , e. coli , s. pneumoniae ) , bartonella , and viral ( coxsackie , echo , influenza , varicella , epstein - barr ) infections and with endotoxemia . recently , we experienced a case of hus in a 16 - year - old boy who was in the acute phase of an epstein - barr virus ( ebv ) infection . he had typical manifestations of hus and ebv infection . he also transiently presented disseminated intravascular coagulation . his renal dysfunction recovered by supportive care , including hemodialysis , plasmapheresis , antihypertensive medication and aspirin . we present this case with a review of the literature as the second report of hus associated with ebv infection ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: staphylococcus aureus and its resistant form , methicillin - resistant s. aureus ( mrsa ) , rank top among the clinically most relevant nosocomial pathogens , leading to increased morbidity , mortality , length of hospital stay and costs . colonized healthcare workers ( hcws ) are capable of developing clinical s. aureus infections , transmitting s. aureus to patients , and introducing s. aureus into their families . understanding s.aureus colonization patterns in hcws may aid in the development and reinforcement of infection control strategies and add to the understanding of s. aureus epidemiology . interestingly , recent reports have revealed higher s. aureus nasal carriage rates in surgeons than in high - risk patient groups and more frequent mrsa nasal carriage in nurses than other hcws , supporting the view that healthcare service may be a risk factor for carriage . however , studies in the healthcare setting generally lack a broader perceptive on the ecological context of hcws in the community and how background prevalence in the general population and households may bias the results . impose their carrier status upon other household members , and the bacterium can be reintroduced into the hospital by intrafamilial spread from and to hcws . moreover , with novel technologies for molecular typing of s. aureus there are better opportunities for detailed epidemiological studies . in the troms staph and skin study ( tsss ) , including 4026 adults aged 3087 years , participating in a population - based health screening survey , we recently reported overall nasal carriage rates of 35 % in men and 20 % in women , and a heterogeneous distribution of s. aureus spa types by gender and age . importantly , we found overlapping population structures for s. aureus nasal isolates in this population - based screening and clinical s. aureus isolates in septic patients from the same geographical area and time period . environment relationships in s. aureus carriage within an unselected general population , focusing on healthcare - associated environmental risk factors ( i.e hospital stay , work in healthcare services ) reported at the screening . thus , to explore s. aureus epidemiology in hcws , we compared screening data on s. aureus nasal carriage , spa types and residing with children , for hcws and non - hcws from the working - age population , 3069 years , participating in tsss . the study subjects in tsss were men and women who participated in the sixth survey of the troms study ( troms 6 ) conducted in 20072008 . the troms study is an ongoing population - based cohort study with five previous surveys undertaken between 1974 and 2001 . based on the official population registry , residents of the municipality of troms were invited to take part in the survey . in troms 6all subjects aged 4042 and 6087 years , a 40 % random sample aged 4359 years , and a 10 % random sample aged 3039 years were invited . in addition to the random samples , 295 participants were invited because they attended the second visit in the fourth survey in 1994 . a total of 12984 men and women aged 3087 years attended troms 6 ( attendance rate 657 % ) . due to lack of capacity and funding , young adult residents ( aged 1829 years ) could not be invited . for the study of s. aureus nasal carriage in a general population , we considered a more evenly distributed sampling across age groups to be most suitable and the inclusion of 4000 observations to be sufficient for analysis of host microbe environment relationships . thus , in troms 6 , during october 2007june 2008 , all attendees aged 3049 years ( n = 1730 ) and random samples of older attendees aged 5087 years ( n = 2629 , relative distribution of birth cohorts as in the municipality ) were asked to participate in tsss , including a nasal swab culture at the screening ( first visit ) and a repeated nasal swab culture at a second visit within a few weeks . a total of 4026 men and women aged 3087 years ( 3049 years , n = 1597 , agemean = 411 , agemedian = 41 ; 5087 years , n = 2429 , agemean = 626 , agemedian = 61 ) had at least one nasal swab culture taken and were included in tsss , and of these , 2997 subjects ( 3049 years , n = 1118 , agemean = 411 , agemedian = 41 ; 5087 years , n = 1879 , agemean = 624 , agemedian = 61 ) had a repeated culture taken ( fig .1 ) . mean interval between cultures was 33 days and for 90 % of the observations the interval was 12 days . not valid swab culture : 91 had no growth in swab culture , 37 had taken antibiotics last 24 h before visit ( systemic or eye drops / ointments ) . the study population . tsss , the troms staph and skin study ; hcw , healthcare worker . * invited to the tsss . not valid swab culture : 91 had no growth in swab culture , 37 had taken antibiotics last 24 h before visit ( systemic or eye drops / ointments ) . for the present study of s. aureus epidemiology in hcws , 37 subjects who had taken antibiotics within 24 h of the first or second visit , were excluded . according to the working age in norway , 373 subjects aged 70 years were excluded . the age of retirement in norway is normally from 67 years , but may be postponed until age 70 years . in 2008 , 22 % of men and 14 % of women aged 6769 years were registered in the norwegian labour force . of the remaining subjects aged 70 years , a total of 217 ( 3049 years , n = 116 , agemean = 409 , agemedian = 41 ; 5069 years , n = 101 , agemean = 597 , agemedian = 59 ) with missing data on hcw status were excluded . thus , for the present analysis 2279 participants aged 3069 years ( 3049 years , n = 961 , agemean = 411 , agemedian = 41 ; 5069 years , n = 1318 , agemean = 587 , agemedian = 59 ) were included ( fig . the study was approved by the regional committee for medical and health research ethics , north norway , and all attendees signed an informed consent form . interviews and clinical examinations were performed at the screening centre by specially trained technicians according to standardized procedures . body height and weightwere measured , and body mass index ( bmi ) calculated ( kg / m ) . two self - administered structured questionnaires covered a broad range of issues related to health and lifestyle , including the question are you residing with children aged 18 years ? ( yes / no ) , referred to asself - reported information on current healthcare - associated environmental exposure was obtained by the interview question do you work in healthcare services ? ( yes / no ) , asked at the second visit . healthcare services were defined as hospital , nursing home , senior care service , general practitioner ( gp ) 's office , and public health centre . the large - scale setting with multiple screening items in troms 6 allowed for only one screening question on workplace . as an open interview question on workplace ( all kinds of professions ) turned out to be too time - consuming during the initial 4 weeks of the survey , it was decided to narrow it down to the specific question on work in healthcare services . this change in data collection led to missing information on hcw status until the fifth week of the survey . thus , for the present study only the data collected after the inclusion of the specific question on work in healthcare services were analysed . the majority of hcws in troms work at the university hospital of north norway ( unn ) . unn has about 4400 employees and is the only hospital within a radius of 200 km . both vestibuli nasi were sampled by the same nacl - moistened sterile rayon - tipped swab and placed in amies charcoal transport medium ( copan , italy ) . within 3 days , all specimens were cultured at unn , using blood agar ( oxoid , uk ) , chromids . aureus , and chromid mrsa agar plates ( biomrieux , france ) . in order to ensure high sensitivity , all culture plates were incubated for 4248 h at 37 c . to retain high specificity , colony morphology was thoroughly examined and the most dominating suspected green colony on the chromid plates was selected for further confirmation as s. aureus by the staphaurex plus ( remel , usa ) agglutination test . all confirmed s. aureus isolates were frozen at 70 c in glycerol - containing liquid media for molecular analysis . s. aureus carrier status was defined by the results of both nasal swab cultures at the first and second visits ; persistent carrier = two positive cultures ; non - carrier = one or no positive culture . our validation in 120 participants in tsss , showed excellent inter - method reliability for s. aureus nasal carrier status using 1 - week interval vs. 26 weeks between the nasal swab cultures [ weighted kappa = 085 , 95 % confidence interval ( ci ) 077092 ] , also implying a low rate of transient colonization . s. aureus nasal isolates from the first ( 996 % ) and second ( 999 % ) visits were spa typed as described elsewhere . primers recommended by ridom gmbh ( germany ) were used , i.e. spa - 1113f and spa - 1514r as described previously by strommenger et al . . polymerase chain reaction ( pcr ) products were sequenced on both strands by macrogen korea or macrogen europe and spa types were assigned using ridom staphtype software ( ridom gmbh , germany ) . according to the ridom staphtype software 264 and 268 different spa typeswere assigned in the first and second visits , respectively . in total , six and seven isolates were not typed due to repeated negative spa pcr amplification or deviating repeat length , respectively . among s. aureus nasal carriers 925 % ( 98/106 ) of hcws and 930 % ( 453/487 ) of non - hcws had the same spa type in both samples ( data not shown ) , also in accordance with the literature . logistic regression models stratified by gender were used to estimate odds ratios ( ors ) and 95 % cis for s. aureus nasal carriage overall and by spa types associated with hcw status . the analysis of spa types was restricted to the nasal swab cultures of the first visit . selected characteristics of hcws and non - hcws were compared by two - sided student 's t test for continuous variables and two - sided pearson 's / fisher 's exact test for categorical variables . we evaluated model fit and plausibility of several covariates and the final multivariable models included age , bmi , current daily smoking ( yes / no ) , alcohol intake ( 2 or 2 times a week ) , recreational physical activity ( three levels ) , household income ( or 37000 / year ) , education level ( or college / university ) , and residing with children ( yes / no ) . we tested whether residing with children modified the association between hcw status and s. aureus nasal carriage in stratified logistic regression analysis . testing for interaction was done by inclusion of the multiplicative terms of the two predictor variables in the models . tests of reliability of the final analyses were done by the hosmer lemeshow goodness - of - fit test . hcws comprised 334 ( 257 % ) of 1302 women and 71 ( 73 % ) of 977 men . hcws were younger than non - hcws in both women and men ( both p values hcws were more often residing with children and reported higher household income , education level , and recreational physical activity level , and less frequent alcohol intake than non - hcws . among men , hcws reported more frequent alcohol intake and hospitalization over the last 12 months than non - hcws ( all p values 005 ) ( table 1 ) . table 1 . characteristics of women and men by healthcare worker status . the troms staph and skin study ( n = 2279 * ) women ( n = 1302 * ) men ( n = 977 * ) non - hcws ( n = 968 ) hcws ( n = 334 ) p non - hcws ( n = 906 ) hcws ( n = 71 ) p age , years525 ( 105 ) 492 ( 89 ) 0001510 ( 96 ) 481 ( 92 ) 001higher education level372 ( 389 ) 155 ( 473 ) 0008386 ( 429 ) 33 ( 465 ) 056lower household income198 ( 220 ) 43 ( 136 ) 000183 ( 94 ) 4 ( 57 ) 030residing with children339 ( 403 ) 147 ( 509 ) 0002366 ( 459 ) 38 ( 576 ) 007hospitalization last 12 months95 ( 99 ) 33 ( 101 ) 09474 ( 82 ) 12 ( 171 ) 001daily smoking198 ( 209 ) 70 ( 211 ) 093178 ( 198 ) 10 ( 141 ) 024alcohol intake 2 times / week207 ( 216 ) 53 ( 161 ) 003219 ( 244 ) 25 ( 352 ) 004low leisure physical activity | | 179 ( 194 ) 40 ( 125 ) 0005173 ( 195 ) 14 ( 203 ) 088body mass index , kg / m265 ( 47 ) 267 ( 50 ) 041276 ( 38 ) 272 ( 36 ) 043diabetes31 ( 33 ) 6 ( 18 ) 02525 ( 28 ) 2 ( 30 ) 071atopic eczema ( ever ) 88 ( 99 ) 36 ( 119 ) 03357 ( 69 ) 6 ( 98 ) 038hcw , healthcare worker.values are given as means ( standard deviation ) , and numbers ( % ) . * numbers may vary due to missing information.two - sided student 's t test for continuous variables . pearson 's test for categorical variables.college / university degree . 37000 / year . | | mostly sedentary recreational physical activity , e.g. watching tv.fisher 's exact test . the troms staph and skin study ( n = 2279 * ) hcw , healthcare worker . values are given as means ( standard deviation ) , and numbers ( % ) . the overall prevalence of s. aureus nasal carriage was 262 % in hcws and 260 % in non - hcws . the corresponding sex - specific rates were 225 % and 184 % in women ( p = 011 ) , and 437 % and 341 % in men ( p = 010 ) , respectively ( table 2 ) . the troms staph and skin study ( n = 2279 * ) total populationcarriers ( % ) or95 % cior95 % ciboth gendersnon - hcws1874487 ( 260 ) ref.ref.hcws405106 ( 262 ) 098 ( 077126 ) 108 ( 082141 ) womennon - hcws968178 ( 184 ) ref.ref.hcws33475 ( 225 ) 129 ( 095176 ) 154 ( 109219 ) mennon - hcws906309 ( 341 ) ref.ref.hcws7131 ( 437 ) 144 ( 088235 ) 145 ( 086245 ) hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . * numbers may vary due to missing information.age - adjusted.multivariable logistic regression model including : age , current daily smoking ( yes / no ) , alcohol intake ( 2 or 2 times a week ) , recreational physical activity ( three levels ) , household income ( or 37000 / year ) , residing with children ( yes / no ) , body mass index , education level ( or college / university degree ) . estimated risk of s. aureus nasal carriage by healthcare worker status . logistic regression analysis . the troms staph and skin study ( n = 2279 * ) hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . multivariable logistic regression model including : age , current daily smoking ( yes / no ) , alcohol intake ( 2 or 2 times a week ) , recreational physical activity ( three levels ) , household income ( or 37000 / year ) , residing with children ( yes / no ) , body mass index , education level ( or college / university degree ) . in multivariable analysis , hcw status was not associated with s. aureus nasal carriage in the total population ( table 2 ) . however , female hcws had a 54 % increased risk of s. aureus nasal carriage vs. non - hcws ( or 154 , 95 % ci 109219 ) , while male hcws did not differ from non - hcws with respect to risk of s. aureus carriage . for women residing with children , hcws had an 86 % increased risk of s. aureus nasal carriage compared to non - hcws ( multivariable analysis : or 186 , 95 % ci 114304 ; p for interaction = 042 ) ( data not shown ) , while in women not residing with children there was no difference in risk by hcw status . for men , there was no pattern of effect modification by family status . at first visit , a total of 61 , 41 , 32 , 26 ,22 and 15 participants were colonized with spa types t012 , t084 , t065 , t021 , t015 and t002 , respectively , which were the predominant spa types including almost one third of the s. aureus nasal isolates . the distribution of the 31 most common ( 4 observations ) spa types in the first sample according to hcw status is shown in figure 2 . the majority of these spa types were observed in both hcws and non - hcws , while seven spa types were restricted to non - hcws , among these spa type t002 .2 . distribution of spa types in non - healthcare workers ( non - hcws ) and healthcare workers ( hcws ) at first visit , nasal swab cultures . spa types with 3 observations are not shown ( 233 different spa types in 298 participants ) . distribution of spa types in non - healthcare workers ( non - hcws ) and healthcare workers ( hcws ) at first visit , nasal swab cultures . spa types with 3 observations are not shown ( 233 different spa types in 298 participants ) . among s. aureus nasal carriers , hcws had 217 and 316 times higher risk of spa types t012 andt015 in the first sample , respectively , compared to non - hcws ( multivariable analysis : or 217 , 95 % ci 116408 and or 316 , 95 % ci 113887 ) ( table 3 ) . table 3 . estimated risk of the six most common spa types at first sample by healthcare worker status . s. aureus nasal carriers ( n = 593 ) , the troms staph and skin studynon - hcws ( n = 487 ) hcws ( n = 106 ) or * 95 % cior95 % cin ( % ) n ( % ) t012 ( n = 57 ) 38 ( 78 ) 19 ( 179 ) 258 ( 142469 ) 217 ( 116408 ) t084 ( n = 31 ) 27 ( 55 ) 4 ( 38 ) 067 ( 023195 ) 074 ( 024223 ) t065 ( n = 27 ) 20 ( 41 ) 7 ( 66 ) 165 ( 068401 ) 194 ( 075498 ) t021 ( n = 20 ) 16 ( 33 ) 4 ( 38 ) 115 ( 038353 ) 148 ( 045479 ) t015 ( n = 19 ) 12 ( 25 ) 7 ( 66 ) 280 ( 107729 ) 316 ( 113887 ) t002 ( n = 12 ) 12 ( 25 ) 0 ( 00 ) hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . * logistic regression model ( unadjusted ) . multivariable logistic regression model including : age and gender.no or estimates due to no spa type t002 in hcws . estimated risk of the six most common spa types at first sample by healthcare worker status . s. aureus nasal carriers ( n = 593 ) , the troms staph and skin study hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . logistic regression model ( unadjusted ) . no or estimates due to no spa type t002 in hcws . when restricting the analysis to s. aureus nasal carriers residing with children , hcws had a 242 times higher risk of spa type t012 in the first sample compared to non - hcws ( age - and gender - adjusted analysis : or 242 , 95 % ci 103570 ) . the association for spa type t012 was particularly strong in male nasal carriers ( age - adjusted analysis : or 461 , 95 % ci 1361561 ) ( table 4 ) . among s.aureus nasal carriers not residing with children , hcws had a fourfold increased risk of spa type t015 in the first sample compared to non - hcws ( age - and gender - adjusted analysis : or 428 , 95 % ci 0991843 ) ( table 4 ) . table 4 . estimated risk of spa types t012 and t015 nasal carriage by healthcare worker status and residing with children . logistic regression analysis . the troms staph and skin studyresiding with children ( n = 244 ) not residing with children ( n = 279 ) non - hcwshcwsor95 % cinon - hcwshcwsor95 % cin ( % ) n ( % ) n ( % ) n ( % ) t012both genders18 ( 96 ) 12 ( 214 ) 242 * ( 103570 ) 18 ( 76 ) 6 ( 140 ) 141 * ( 050396 ) women8 ( 136 ) 7 ( 184 ) 161 ( 052502 ) 9 ( 100 ) 6 ( 194 ) 189 ( 060593 ) men10 ( 78 ) 5 ( 278 ) 461 ( 1361561 ) 9 ( 66 ) 0t015both genders4 ( 21 ) 3 ( 54 ) 361 * ( 0701867 ) 5 ( 21 ) 4 ( 93 ) 428 * ( 0991843 ) hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . * multivariable logistic regression model adjusted for age and gender.multivariable logistic regression model adjusted for age.no or estimate due to no spa type t012 in male hcws not residing with children . estimated risk of spa types t012 and t015 nasal carriage by healthcare worker status and residing with children . logistic regression analysis . the troms staph and skin study hcw , healthcare worker ; or , odds ratio ; ci , confidence interval . no or estimate due to no spa type t012 in male hcws not residing with children . in this large population - based study with participants aged 3069 years with repeated nasal swab cultures , working in healthcare services was associated with a 54 % increased risk of s. aureus nasal carriage in women . for men , work in healthcare services and residing with children were associated with increased prevalence of common spa types . our study suggests that a synergism between environmental risk factors ( work and household ) is of importance for s. aureus carrier status in hcws . to our knowledge , this is the first study which reports that female hcws have a higher risk of s. aureus nasal carriage than female non - hcws in a general working - age population . interestingly , other studies confined to hcws , observed higher nasal carriage rates of mrsa in nurses than in other healthcare professionals , and cited increased patient contact as a cause . however , the majority of the norwegian healthcare workforce are nurses and auxiliary nurses , and about 90 % of these are women . thus , our findings suggest that work in healthcare services is an environmental risk factor for s. aureus nasal carriage in women , due to a substantial amount of contact with patients and the elderly in residential care when working as nurses and auxiliary nurses . however , epidemiological evidence supports a similar mechanism for transmission of methicillin - sensitive s. aureus ( mssa ) and mrsa usually via direct contact with patients and other close contacts ( household members , etc . ) we observed that working in healthcare services in combination with residing with children was a high risk cluster for s. aureus carriage in women . our findings are in agreement with current literature supporting the view that contact transmission within hcws ' families may affect the burden of mssa and mrsa infections in hospitals . importantly , residing with children per se was not associated with s. aureus nasal carriage in our study , and number of children aged 18 years and age did not differ between hcws and non - hcws ( results not shown ) . information on childcare was not included in our study , and attending kindergarten has been associated with increased risk of s. aureus colonization in children . however , it can be assumed that use of kindergarten was not a major confounder in our analysis , as there have been places in kindergarten for all children in troms since 2005 and 894 % of female non - hcws residing with children were part - time or full - time workers . thus , we hypothesize that the environmental pressure caused by high rates of contact transmission of s. aureus from both patients and children may exceed the ability of female hcws ( i.e through hand hygiene , immune responses ) to defend themselves against colonization . the population structure of s. aureus colonizing hcws and non - hcws was similar , as expected from others and our previous comparative study of clinical and nasal carrier s. aureus isolates in troms . however , we observed that work in healthcare services was associated with an increased risk of spa types t012 and t015 , which both ranked in the top five in our study and are also frequent worldwide . thus , we may expect spa types t012 and t015 to be frequent causes of autoinfections in patients in the community and in hospitals , with an increased potential for transmission , that may also partly explain our findings . among men , hcw status and residing with children predicted s. aureus carriage by spa types and not overall carriage rates . even though there is considerable degree of uncertainty in our estimates , we can hypothesize that in the male human population , common s. aureus spa types have specific main niches defined by environmental factors . the female preference of the common spa type t012 in our study population , may possibly confound the results in women . the main limitation of our study is the lack of information on profession , workplace and patient contact . thus , future prospective population - based studies including work and home exposures are needed to improve our knowledge about high - risk groups and environmental targets for more effective prevention of s. aureus carriage in hcws . as the prevalence of s. aureus carriage in younger adults is relatively high , particularly in men , the role of work in healthcare services for carriage should also be explored in the working population aged 30 years . furthermore , the s. aureus epidemiology in hcws having contact with the elderly requires increased focus given the fact that nursing - home residents are a population at risk for carrying s. aureus and mrsa . recent antibiotic use not registered at the screening ( i.e. ceased 24 h before visit ) and lack of enrichment during culturing may have caused false negatives independently of hcw status . thus , non - differential misclassification of s. aureus nasal carrier status may have biased our odds ratio estimates towards null . the major strengths of our study are the population - based design , high participation rate , large set of observations , validated outcome variable including spa type , gender - stratified analysis , and the adjustment for major confounders ( i.e. age , bmi , smoking , etc . ) . furthermore , representative data were achieved as demonstrated by the age distribution within the different age groups included . the absence of mrsa in this study is in line with the low prevalence of mrsa in clinical s. aureus samples registered in the norwegian surveillance programme during 20072008 . importantly , the surveillance data do not reflect a healthy population , and therefore can not be directly compared to mrsa / mssa colonization rates in our study , including healthy persons only ( i.e not hospitalized or institutionalized ) . in conclusion , our study indicates that work in healthcare services in combination with residing with children is a high - risk cluster for s. aureus carriage in women . the synergism of work and home environmental risk factors should be addressed in future studies to increase our understanding of s. aureus epidemiology in hcws and suggest novel targets for improved infection control strategies against exogenous mssa and mrsa infections in patients .\noutput:\n" }, { "from": "agent", "value": "summaryhealthcare workers ( hcws ) may be a reservoir for staphylococcus aureus transmission to patients . we examined whether hcw status is associated with s. aureus nasal carriage and population structure ( spa types ) in 1302 women ( 334 hcws ) and 977 men ( 71 hcws ) aged 3069 years participating in the population - based troms study in 20072008 . multivariable logistic regression models were used . while no methicillin - resistant s. aureus ( mrsa ) was isolated , overall , 262 % of hcws and 260 % of non - hcws were s. aureus nasal carriers . for women overall and women residing with children , the odds ratios for nasal carriage were 154 [ 95 % confidence interval ( ci ) 109219 ] and 186 ( 95 % ci 114304 ) , respectively , in hcws compared to non - hcws . moreover , hcws vs. non - hcws had a 217 and 316 times higher risk of spa types t012 and t015 , respectively . this supports the view that hcws have an increased risk of s. aureus nasal carriage depending on gender , family status and spa type ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: x - linked hyper - igm syndrome ( xhigm ; higm1 ; omim : 308230 ) is one type of primary immunodeficiency diseases ( pids ) , resulting from defects in the cd40 ligand / cd40 signaling pathways leading to impairment of immunoglobulin isotype switching in b cells and characterized by recurrent infections in association with markedly decreased serum igg , iga , and ige levels but normal or elevated serum igm levels . . over 50 % of patients have chronic or intermittent neutropenia , often associated with oral ulcers . opportunistic infections , especially cryptosporidium parvum and pneumocystis jirovecii infections , are common and prominent clinical feature of the patients . besides the susceptibility to recurrent bacterial and opportunistic infections , these patients are prone to autoimmune manifestations , especially hematologic abnormalities , arthritis , and inflammatory bowel disease . furthermore , an unusual susceptibility to liver , pancreas , or biliary tract tumours has been reported . cd40l is the disease - causing gene of xhigm , located in xq26.3 - xq27 .1 and containing five exons and four intervening introns . the corresponding translated protein cd154 ( also called cd40l , gp39 , tnfsf5 , or trap ) contains 261 amino acids and is mainly expressed on activated mature t cells . its receptor , cd40 , is expressed on a variety of cells , such as b cells , monocytes / macrophage , dendritic cells , endothelial cells , and epithelial cells . cd40 - cd154 interactions provide a costimulatory signal for t cell activation and can lead to b cell proliferation and immunoglobulin class switching , affecting both cellular and humoral immunity . xhigm is the most common subtype of hyper - igm syndromes ( affecting about 70 % of the patients ) . diseases resulting from mutations in aicda ( i d : 57379 ) , cd40 ( i d : 958 ) , ung ( i d : 7374 ) , nemo ( i d : 8517 ) , or nfkbia ( i d : 4792 ) genes are all involved in the cd154 - cd40 - nf - b pathways and affected the class switch recombination ( csr ) , somatic hypermutation ( shm ) , or germinal center formation and form the subtypes of hyper - igm syndromes . the heterogeneity of hyper - igm syndrome brings the challenge for diagnosis and accurate and reliable molecular testing methods are needed . withdiagnosed patients accumulated , people began to analyze the clinical features and mutation characteristics of these patients since 1992 . retrospective research results of xhigm patients in europe , usa , japan , and latin america were published . , we collected clinical data of chinese xhigm patients diagnosed and followed up in our center , reviewed their clinical and immune features , therapy , and response , and investigated the mutation characteristics , intending to increase our knowledge of this disease and finally improve the quality of life in these patients . patients in present study were first diagnosed in hospitals affiliated to shanghai jiao tong university school of medicine or referred from other hospitals and followed up in shanghai children 's medical center ( also affiliated to shanghai jiao tong university school of medicine ) during 19992013 . the inclusion criteria were low sera igg and iga ( 2 standard deviations below normal value for age ) , normal or elevated serum igm , and compatible infectious events . patients with secondary immunodeficiency conditions such as hiv or congenital rubella infections , immunosuppressive drug use , or neoplasms were excluded . then cd154 expression on active t cells was detected by flow cytometry and sequences of cd40l gene were analyzed . an informed consent was obtained from each patient 's parent or guardian before enrollment in the study . clinical data were collected from the patients ' medical records , including initial clinical manifestation , onset age , diagnosis age , parental consanguinity , family history of immunodeficiency , recurrent infections , autoimmune diseases or malignancy diseases , vaccination and allergic history , complication , laboratory tests ( including immunoglobulin level and lymphocyte subpopulations ) , and treatments . a total of 5 ml venous blood was collected from patients for pathogen screening and gene sequencing . detection of cd154 expression on activated cd4 + t cells was performed by flow cytometry ( facscan , becton dickinson , usa ) using specific fluorescent - labeled monoclonal antibodies according to the method described previously . genomic dna was isolated from heparinized peripheral blood by using the dp319 kit ( tiangen biotech co. ltd . , the individual exons of cd40l gene , including exon - intron boundaries , were amplified by polymerase chain reaction ( pcr ) as previously described . the system for pcr reaction contained 13.5 l ddh2o , 1 l primer for each direction , and 8.5 l 2 taq pcr mastermix ( containing 0.1 utaq / l , 500 m dntp , 20 mm tris - hcl ( ph 8.3 ) , 100 mm kcl , and 3 mm mgcl2 ( tiangen biotech co. ltd . , china ) , with total volume 25 l ) . amplification conditions were 95c for 10 minutes , then 40 cycles of 94c for 30 seconds , 55c for one minute , and 72c for 30 seconds , followed by a final extension of 72c for 2 minutes . human snp databases ( dbsnp in ncbi and 1000 genomes ) were also searched to confirm the detected mutations . bioinformatics software polyphen - 2 ( http://genetics.bwh.harvard.edu/pph2/ ) and mutationtaster ( http://www.mutationtaster.org/ ) were used to predict the effects of point mutations . from 1999 to 2013 , 20 patients from 19 unrelated families ( p2 and p3 are cousins ) were diagnosed as xhigm , considering the clinical manifestations , lab examination , family history , decreased cd154 expression , and the mutation of cd40l gene ( table 1 ) . the median onset age of these patients is 8.5 months ( range : 20 days21 months ) . and the median of diagnosis lag is 50 months ( range : 5 months15 years ) . half of the patients had positive family histories of previous sibling deaths at an early age and the diagnosis lag in them was much shorter than that in patients with negative family histories ( 3123 months versus 8555 months , p = 0.015 ) . the most common symptoms of xhigm patients were recurrent sinopulmonary infections ( 18 patients , 90 % ) , neutropenia ( 14 patients , 70 % ) , oral ulcer ( 13 patients , 65 % ) , and protracted diarrhea ( 13 patients , 65 % ) . respiratory and gastrointestinal systems were more frequently affected . skin ( 7 patients , 35 % ) , bone and joint system ( 4 patients , 20 % ) , central nervous system ( 3 patients , 15 % ) , and urinary system ( 2 patients , 10 % ) were also affected ( detailed in table 1 ) . the median onset age of diarrhea was 12.0 months ( range : 20 days to 20 months ) . among them , two patients ( p10 , p11 ) were diagnosed with inflammatory bowel diseases ( ibds ) under enteroscopes , and cryptosporidium was isolated from the stool of p11 . the median onset time of adverse drug reactions was 2 months old ( range : 50 days7 months ) . the other four patients had severe local adverse events after bcg vaccinations , presenting ulceration 10 mm or suppurative lymphadenitis , and received surgeries to drain . among them , p12 was reinfected by tubercle bacillus at 35 months old and recovered after antituberculosis drug therapy . besides , another patient p14 suffered pulmonary tuberculosis at 8.5 years old , with restrictive pulmonary capacity and splenomegaly and lymphadenopathy . the patient received isoniazide and rifampicin treatment unregularly for nearly one year and developed tuberculous meningitis and died at 10 years old . p11 had cryptosporidium infection , with protracted diarrhea and elevated liver enzyme . moreover , this patient developed chronic kidney disease , presenting oliguria , edema , acidosis , increased creatinine concentration , and decreased glomerular filtration rate ( gfr ) , lasting for over four months . p9 also developed chronic kidney disease , with oliguria , albuminuria , hematuria , increased serum creatinine and urea nitrogen concentration , and anemia for over three months . anemia was found in seven patients ( table 3 ) . among them , p10 and p11 had ibds and the chronic bloody purulent stools might partly cause the anemia . p9 and p11 had chronic kidney disease which may lead to renal anemia . the median serum igm concentration was 3.15 g / l ( range : 0.7411.7 g / l ) . three patients ( p5 , p9 , and p11 ) exhibit significantly decreased cd4 / cd8 ratio . they all had severe clinical symptoms and the decreased ratio reflected the impaired cellular immunity . eighteen unique mutations were identified in 20 patients from 19 unrelated families ( p2 and p3 were cousins and they had the same mutation . besides , p12 and p16 had the same mutation ) . among the 19 families , we found 7 deletions , 6 missense mutations , 2 nonsense mutations , 2 splice site mutations , and 2 insertions ( table 4 ) . the mutations were distributed throughout the entire gene , affecting all the domain of the protein , and exon 5 was the most frequently affected region ( 10/19 , 52.6 % ) . p5 developed sspe after measles virus infection at 15 years old and died within one year . p14 was infected by mycobacterium tuberculosis and died of tuberculous meningitis at 10 years old . p17 had severe diarrhea and pneumonia since 14 months and died at 2 years old . p3 and p13 received hematopoietic stem cell transplantations ( hsct ) but suffered from severe infections and died at 22 months and 56 months , respectively . the other twelve patients were alive till now , with the median age of 8 years old ( range : 227 years old ) . fifteen patients ( 75 % ) received intravenous immunoglobulin ( ivig ) treatment ( table 1 ) . eight patients could receive ivig regularly ( 400 mg / kg / month ) after diagnosis as higm . all of them were free of severe bacterial infections , although three of them still had recurrent oral ulcers . seven patients could not receive full - dose ivig regularly . among them , one patient ( p14 ) died of tuberculosis infection . two patients still had recurrent bacterial infections ( p2 had recurrent otitis media and perianal abscess . the other five patients did not receive ivig therapy , including the two patients who died from measles infection ( p5 ) and severe diarrhea and pneumonia ( p17 ) . four patients received hematopoietic stem cells from hla - identical unrelated donors and they had clinical remissions and were followed up from months to 6 years . the other two patients had hla - half identical sibling donors and died from severe infections ( table 5 ) . skin , bone and joint system , central nervous system , and urinary system were also involved . in this study , cardiovascular disease , infections , and nonsteroidal anti - inflammatory drugs ( nsaids ) are accepted risk factors for causing chronic kidney disease . p9 was born with congenital heart diseases ( ventricular septal defect and patent ductus arteriosus ) . opportunistic infections , especially cryptosporidium parvum and pneumocystis jirovecii infections , are common and prominent clinical feature of xhigm patients . besides , infections caused by tubercle bacillus were detected . a number of pids are reported to be susceptible to severe mycobacterial disease following vaccination with bcg , including severe combined immunodeficiency ( scid ) , chronic granulomatous disease ( cgd ) , and mendelian susceptibility to mycobacterial diseases ( msmd ) . increased bcg infections are also reported in patients with hyperimmunoglobulin e syndrome ( hies ) and xhigm , with less prevalence and severity of bcg complications compared with the pids mentioned above . in a european survey , only two of the 56 xhigm patients present with tuberculosis . however , in our study concerning 20 xhigm patients , we found six patients had bcgitis during the first year of life . one more patient suffered pulmonary tuberculosis and tuberculous meningitis and died at 10 years old . in another cohort study focusing on chinese patients , five ( 38 % ) of the 13 xhigm patients had lymphoid tuberculosis after bcg vaccination , the relatively high incidence of which was very similar to ours . an indian research group also reported that two patients with pulmonary tuberculosis and one patient with disseminated bcgiosis were found in the cohort study including seven xhigm patients . global tuberculosis report 2013 by who pointed out that india and china had the largest number of tuberculosis cases , taking up to 26 % and 12 % of the global total , respectively . in both china and india , bcg vaccine is given to every newborn after birth to prevent tuberculous meningitis and disseminated disease , while in europe , where incidence and prevalence of tuberculosis are low , less than half of the european countries have nationally recommended bcg vaccination . the differences in tuberculosis prevalence and bcg coverage may partly contribute to the differences of mycobacteria complications in xhigm patients . some recent discoveries may help to elucidate the susceptibility to mycobacterial infections in xhigm patients . hayashi 's results indicated that cd40 - cd154 signaling might be an important step in host immune response against mycobacterium avium infection . revealed that activation of monocytes via cd40l resulted in a vitamin d - dependent antimicrobial activity against mycobacterium tuberculosis . demonstrated that activated t cells from xhigm patients produced markedly reduced levels of ifn - and failed to induce antigen - presenting cells to synthesize il - 12 . we should continue to observe the susceptibility to tuberculous infections in xhigm patients and be concerned about the immunity affected by tuberculous infection . furthermore , we found two patients with varicella - zoster virus infections , one patient with measles virus infections , one patient with fungus infections , and one patient with cryptosporidium infection , which all indicated the defects in cellular immunity . besides , more mutations on cd40l gene were reported in other studies . considering the published results , the common type of mutations in cd40l might be missense mutations , followed by deletion / insertion mutations , nonsense mutations , and splice site mutations ( detailed in table 6 ) . in our results , missense mutations and deletion / insertion mutations were the main types , composing about 3/4 of the mutations . pointed out that w140 represents a mutational hotspot . in lee 's study , four possible hotspots were identified that were thr254 , ivs1 + 1 g t , ivs3 + 1 g a / t , and ivs4 + 1 g c . in the cd40lbase , mutations were concentrated in some special positions ; that is , mutations in c218 , t254 , and w140 have been identified in more than 10 patients , respectively , till now . in this study , we identified two splice site mutations ( p4 : ivs21 g a and p10 : ivs42 a g ) . separately reported a ivs31 g a mutation , resulting in exon 4 skipping and a protein with 21 - amino acid truncation . weller et al . reported an ivs21 g t mutation , resulting in exon 3 skipping and forming a protein consisting of 107 amino acids . in our study , p4 mutated in 3 - acceptor splice sites , the same positions as the three cases , and it can be inferred that this mutation could also result in the skipping of exon 3 . for the mutation in p10 , it has been reported in 1994 . mutation in the acceptor site of intron 4 allowed utilization of a cryptic acceptor site and a few base pairs downstream in exon 5 and led to 8 - nucleotides deletion in p10 . six patients had missense mutations in this study . from data published in cd40lbase ( updated to 2011 ) , the most frequent amino acid substitutions were leu to ser / pro , thr to met , gly to arg , and ala to asp / glu . thusberg and vihinen reported that there were 10 invariant positions corresponding to the amino acids w140 , l161 , g167 , y169 , y172 , l205 , g226 , g227 , l231 , and g257 in cd40l , according to sequence alignment and calculation . disease causing mutations are typically located at conserved positions within a protein family , since these positions are usually essential for the structure and / or function of the protein . in our study , the mutation in p6 ( gly167arg ) was previously reported in two iranian patients . substitution from glycine to arginine introduced a larger side chain group and a positive charge , which would profoundly change structure and functions of the protein . the mutation in p20 ( p.trp140arg ) was reported as one of the hotspots and eleven patients in all had been reported to have this mutation until now . trp140 is a large hydrophobic residue buried inside the protein while arginine had a large hydrophilic side chain with positive charge . mutation in p14 ( p.leu205ser ) changed the conserved hydrophobic residue into a hydrophilic residue . proline was involved in the mutations in p11 ( p.pro10ser ) and p17 ( p.ala208pro ) . proline is the only amino acid forming a ring with the backbone and bends the main chain of the protein in a characteristic way . the substitution in the two patients would profoundly change structure and functions of the protein . effects of the four novel point mutations were analyzed by using bioinformatics software polyphen - 2 and mutationtaster . polyphen - 2 predicted probably damaging effects to the protein with a score over 0.99 , respectively . mutationtaster predicts that mutations in p13 , p14 , and p17 were disease causing , with probability value over 0.98 . two patients had nonsense mutations at codon 236 and codon 218 , both of which were already reported . cys218 was involved in formation of a disulfide bridge and nonsense mutation ( p.c218x ) had been reported in at least twelve xhigm patients and one carrier , usually associated with more severe clinical presentation . nine patients had insertion / deletion mutations , all changing the reading frames and leading to large changes of the protein structure . p12 and p16 were from unrelated families and they had the same mutation ( g.2091_2094deltaga , c.158_161deltaga , p.ile53fsx13 ) . this mutation had been reported in at least another 6 unrelated patients and was the fifth common mutation position in the cd40lbase . the 4 deleted nucleotides were very close to the acceptor splice site of intron 1 and were flanked by repeat sequences , suggesting that these mutations might be caused by slipped mispairing mechanisms . the frame shift deletion led to a premature stop codon within the extracellular unique domain . p2 and p3 were cousins and they had the same mutation ( g. 186delg ) . the deletion in exon 1 led to a premature stop codon in the transmembrane domain . in conclusion , we retrospectively investigated the clinical , immunological , and molecular features of 20 chinese xhigm patients diagnosed and followed up in our center . we identified 18 unique mutations in cd40l in these patients , with 12 novel mutations . various mutations reflected the heterogeneity of cd40l gene , and we should go further to investigate the relationship between genotype and phenotype .\noutput:\n" }, { "from": "agent", "value": "x - linked hyper - igm syndrome ( xhigm ) is one type of primary immunodeficiency diseases , resulting from defects in the cd40 ligand / cd40 signaling pathways . we retrospectively analyzed the clinical and molecular features of 20 chinese patients diagnosed and followed up in hospitals affiliated to shanghai jiao tong university school of medicine from 1999 to 2013 . the median onset age of these patients was 8.5 months ( range : 20 days21 months ) . half of them had positive family histories , with a shorter diagnosis lag . the most common symptoms were recurrent sinopulmonary infections ( 18 patients , 90 % ) , neutropenia ( 14 patients , 70 % ) , oral ulcer ( 13 patients , 65 % ) , and protracted diarrhea ( 13 patients , 65 % ) . six patients had bcgitis . six patients received hematopoietic stem cell transplantations and four of them had immune reconstructions and clinical remissions . eighteen unique mutations in cd40l gene were identified in these 20 patients from 19 unrelated families , with 12 novel mutations . we compared with reported mutation results and used bioinformatics software to predict the effects of mutations on the target protein . these mutations reflected the heterogeneity of cd40l gene and expanded our understanding of xhigm ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: ebbd 17.2 ( stappia indica ) : https://www.ncbi.nlm.nih.gov/bioproject/328867 ebb 35.1 ( nitratireductor aquibiodomus ) : https://www.ncbi.nlm.nih.gov/bioproject/prjna327597 sbbc 49 ( stappia indica ) : https://www.ncbi.nlm.nih.gov/bioproject/prjna328866coral reefs are one of the most diverse , yet vulnerable , ecosystem in the world . indeed , local and global environmental changes have increased the vulnerability of these ecosystems to develop coral diseases of probable infectious nature . the black band disease ( bbd ) was one of the first documented coral diseases and affects coral reefs worldwide . although the etiology of the bbd is not completely understood it appears that is caused by a consortium of cyanobacteria that might infringe direct damage and / or facilitate the colonization by opportunistic bacteria . hereby we present three high quality draft genome assemblies from three bacteria isolated from corals affected with bbd . coral samples were collected in santa marta bay , colombia , and were subsequently macerated and plated on lb or marine agar . whole - genome sequencing was performed using the illumina hiseq 2000 system with paired - end reads ( table 1 ) . in order to ensure the best computational results we tested different pre - processing and assembly methods . sequence reads were preprocessed using the trimmomatic , sickle , and trim galore tools . a de novo genome assembly was conducted using spades , velvet , and abyss , iterating over different k - mers and other software - specific parameters . an assembly based on a reference genome was not feasible due to the lack of published genomes for the species under study . the taxonomical classification of the organisms under study were analysed with the rnammer tool to find the 16s sequence and the ez taxon tool to find the most exact taxon position based on their similarity value . based on this analysis the bacteria under studywere identified as stappia indica to strain ebbd 17.2 and sbbc 49 , and nitratireductor aquibiodomus to strain ebb 35.1 . this annotation process allowed us to identify 4429 protein - coding sequences to the strain ebbd 17.2 , 66 of which were associated with the virulence / resistance process ( table 1 ) . for strainsebb 35.1 and sbbc 49 , we found 4378 and 4658 protein - coding sequences respectively , where 95 and 692 sequences were associated with virulence / resistance for strains ebb 35.1 and sbbc 49 , respectively ( table 1 ) . these bacterial genomes were deposited at ddbj / ena / genbank databases under the accession mbqf to the bacterium 1 ( stappia indica ) , mayb to the bacterium 2 ( nitratireductor aquibiodomus ) and mbqe to the bacterium 3 ( stappia indicia ) , with their corresponding versions mbqf01 , mayb01 and mbqe01 . this work was funded by direccin de investigacin y extensin and direccin acadmica , at national university of colombia ( grant number 32687 ) , and by a grant from the colombian\noutput:\n" }, { "from": "agent", "value": "we announce the draft genome sequence of three gram - negative bacteria isolated from coral tissues affected with the black band disease ( bbd ) , identified with the ncbi 's assembly database accession numbers : mbqf , mayb and mbqe . these genome drafts constitute an useful tool for the characterisation of these bacteria and for the understanding of the relationship between the microbial consortia associated with the disease and the onset and progression of the pathology ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: alcohol is considered a social evil worldwide owing to its vast array of associated problems and complications , which may manifest in medical , legal or social domains ( 1 ) . excessive and prolonged alcohol use may lead to permanent structural and functional damage to the brain ( 2 ) . alcohol - related dementia ( ard ) has received little recognition as a distinctive clinical entity , predominantly due to doubts regarding the etiopathogenesis and lack of pathophysiological profile typical for ard . recently , researchers have showed interest owing to its magnitude , ageing of population and focus of health bodies on alcohol - related issues across the world ( 3 ) . there are doubts and debates concerning ard whether the cognitive impairment or dementia is due to direct ethanol neurotoxicity , or representation of another underlying pathology ( thiamine adeficiency ) or if it is multifactorial ( neurotoxicity as well as multivitamin deficiency ) ( 4 ) . the correlation between the amount and duration of alcohol consumption and occurrence of ard is not well - established . this is due to different types and strengths of liquor available across the countries , varying definitions of leisure drinking and pathological drinking , different cultural beliefs , and different definitions of standard drink ( 5 ) . varying patterns of drinking ( duration , quantity , binge , abstinent and withdrawal periods in between ) along with difficulties in obtaining an accurate self - report of alcohol use ( recall problems ) may complicate attempts of correlating alcohol abuse to cognitive impairment . . these may be the lifestyles of alcohol abusers , concomitant other substance abuse , associated complications like head injury , psychiatric comorbidities , and a higher rate of vascular risk factors , which may independently predispose an individual for cognitive decline ( 6 ) . there also is a great heterogeneity in the terms that describe ard across different countries . other terms that have been used are alcohol - related brain damage , alcohol - related brain injury and alcoholic amnesia syndrome ( 7 ) . considering these controversies surrounding the concept of ard , we have tried to review the nosology , prevalence , presentation , underlying pathology and management of ard in this paper . we did computerized searches to find published articles on dementia or cognitive impairment related to alcohol . articles were retrieved by searching pubmed database for terms alcohol and dementia , alcohol and cognitive impairment , and alcohol and wernicke - korsakoff mentioned in the title of the published papers . the search revealed 73 , 50 and 8 articles , respectively for each of the search terms mentioned above . articles without abstracts ( n = 23 ) , case reports ( n = 11 ) , and animal studies ( n = 12 ) were excluded . after reading the abstract of these articles , only those discussing dementia and cognitive impairment , primarily due to alcohol were considered ( n = 72 ) . the full text of the shortlisted articles were retrieved and read in full by the authors . cross - references from selected studies were searched and further relevant articles were considered for inclusion . the present diagnostic criteria for alcohol - related cognitive impairment focus only on alcohol amnesic syndrome and ard ( 8 ) . the two primary classification guidelines , the international classification of diseases , icd - 10 ( 9 ) and the diagnostic and statistical manual of mental disorders , dsm - 5 ( 10 ) also differ in description of ard . amnesic syndrome , according to icd - 10 ( f10 .6 ) is characterized by impairment of both recent and remote memory , with preservation of immediate recall . f10 .73 of icd - 10 classifies residual and late - onset psychotic disorder , characterized by changes of cognition and personality , induced by psychoactive substance , with subtype dementia . the dsm - 5 has included a specifier of substance use in the diagnostic criteria for major / mild neurocognitive disorders ( the term that has replaced dementia in dsm - 5 ) . major / mild neurocognitive disorders supersede the diagnosis of alcohol - induced persisting dementia and alcohol - induced amnestic disorder , although these terms still are in use . many clinicians prefer this term to ard because it represents the heterogeneity of clinical features more appropriately , the stigma associated with the term dementia and alcohol gets avoided , and ard s non - progressive nature gets distinguished from other degenerative disorders . the diagnostic and statistical manual of mental disorders , 4th edition ( dsm - iv ) included a category for alcohol - induced persisting dementia . it was characterized by neurocognitive decline associated with alcohol use , in the absence of other causes of dementia ( 11 ) . the wernicke - korsakoff syndrome ( wks ) is described in the dsm - iv under alcohol - induced persisting amnestic disorder . oslin refined the diagnostic criteria for ard by including duration and severity of alcohol consumption and a minimum abstinence time , for ahe expected this classification would bring more clarity and stimulate further research in this area ( 12 ) . even till now , only a few studies have adopted these criteria and they still need research for being conclusive ( 13 - 15 ) . it can be concluded that presently , clinical judgment guides the current diagnostic criteria for ard . this has prognostic significance as ard is considered less progressive than other forms of dementias ( 7 ) . presently , most of the cases of dementia are attributed to alzheimer s disease , vascular causes and lewy body dementia . alcohol - related dementia is largely overlooked or seen as a comorbid factor ( 7 ) . the incidence and prevalence of ard varies across studies as there are no defined diagnostic criteria . variations may also be due to the differences in the socio - demography of study samples . a review indicated a high prevalence of alcohol abuse in dementia patients ( 9 % to 22 % ) and 10 % - 24 % prevalence of dementia in alcohol abusers ( 16 ) . it is interesting to note that the prevalence data of ard is from the cohort that consists mainly of today s younger and middle - aged generation . thus , it might be predicted that ard rates would be even higher in the future , given that chronic alcohol misuse will continue . hence , it becomes important for the studies to include those less than 60 years of age ( 16 ) . an english epidemiological study of younger - onset dementia ( onset before 65 years ) found 10 % rates of ard ( 17 ) . an australian analysis demonstrated that ard was found in 1.4 % of all patients with diagnosed dementia but its prevalence was 22 % in cases who had onset before 65 years ( 18 ) . a study found a direct association between cognitive decline , and chronicity and severity of alcohol use ( 19 ) . prevalence rates of ard in hospitals and clinics have been reported to account for 10 % to 24 % of all dementias subtypes ( 16 , 20 ) . reports from neurology and memory clinics suggest lower rates of ard in dementia cases , around 3 % - 5 % , indicating less referral to these centers ( 21 , 22 ) . older studies have suggested that of all cases of dementia , ard accounts to approximately 10 % ( 23 ) . in a review by smith , heavy use of alcohol was a contributory factor in approximately 24 % cases of dementia ( 24 ) . an ongoing controversy concerns the amount of alcohol that predisposes an individual for development of ard . united kingdom s department of health limits daily alcohol consumption to 2 - 3 units for women and 3 - 4 units for men . a number of studies have found a j - shaped or a u - shaped relationship between the amount and consequences of alcohol use on cognitive impairment . light - to moderate alcohol consumption is associated with a lower risk of dementia ( 25 ) while heavy drinking is associated with a higher risk ( 26 ) . a meta - analysis found that small amounts of alcohol may protect against alzheimer s dementia ( 27 ) while others suggest that it is protective against all forms ( 28 ) . however , a recent study concluded that even heavy regular drinking is not a direct cause of cognitive impairment in later life ( 29 ) . studies have shown that ard patients are mostly males , unmarried , have comorbid mental and physical conditions , likely to be identified through hospital admissions , are socially isolated , and do not have social support ( 14 , 30 ) . the prevalence rate estimates from post - mortem studies are 1 % - 2 % of the general population and 10 % of alcohol consumers ( 31 , 32 ) . netherlands had a prevalence of 48 per 100,000 ( 33 ) , while incidence rates of 8 per 100,000 were estimated in scotland in 1995 ( 34 ) . a study of hospital admissions identified the korsakoff syndrome ( ks ) and wernicke s encephalopathy ( we ) cases to be 0.05 % and 0.03 % of all admissions , respectively ( 18 ) . the evidence from neuroimaging , neuropathological reports and autopsy evaluations suggest some degree of brain pathology in individuals diagnosed with an alcohol related disorder ( 35 ) . volume shrinkage , altered glucose metabolism and perfusion along with evidence of markedly decreased neuron density are commonly reported . computed tomography ( ct ) scans showed wider cerebral sulci and larger ventricles suggestive of atrophy ( 38 ) . the evidence of neuro - circuit disturbances is seen in form of significant loss of white matter ( most prominent in the prefrontal cortex , cerebellum and corpus callosum ) on functional imaging . neuronal loss is also noted in the superior frontal association cortex , cerebellum and hypothalamus ( 2 , 39 ) . greater cognitive impairment has been associated with multiple and repeated withdrawal due to greater neuronal damage . a study showed a greater degree of cognitive impairment in patients undergoing two or more detoxifications compared with those with one or none ( 40 ) . a study found fewer structural brain changes in treatment naive patients compared to clinical patients undergoing detoxification ( 41 ) . it is postulated that brain damage worsens with repeated withdrawals , which may be associated withkindling - effect of worsening of withdrawal symptoms . however , whether these changes are permanent or not and whether they relate to neurotoxicity in isolation , yet remains to be established . alcohol - induced brain injury may be attributed to a direct neurotoxic effect of alcohol , oxidative stress , excitotoxicity , apoptosis , disruption of neurogenesis and mitochondrial damage ( 42 ) . it is proposed that repeated binge drinking and withdrawal facilitates neuronal injury by glutamate - induced excitotoxicity , mediated by upregulated n - methyl - d - aspartate receptors . this leads to increased intracellular calcium , which mediates oxidative stress , along with loss of cholinergic muscarinic receptors . dose related damage has been observed in the hippocampus , hypothalamus , and cerebellum in animal studies ( 43 , 44 ) . cholinergic neurotransmitter system ( particularly in basal forebrain ) , implicated in attention , learning and memory also appears to be impacted . imaging studies of isolated cases of uncomplicated alcoholic individuals ( without any nutritional deficiency , hepatic failure , brain injury ) have confirmed structural abnormalities , including changes to the corpus callosum , pons , and cerebellum ( 45 ) . abstinence results in improvement in motor abilities and cognition , and is accompanied by reversal of white matter shrinkage ( 45 , 46 ) . restoration of myelination and axonal integrity is the chief mechanism thought to be behind recovery from white matter damage ( 46 ) . this leads to a hypothesis that ard is primarily due to thiamine ( vitamin b1 ) deficiency . alcohol directly interferes and compromises thiamine metabolism . also , because of poor dietary nutrition , alcohol users are at a higher risk of thiamine deficiency ( 31 ) . the wernicke s encephalopathy is an acute neurological disorder , precipitated by thiamine deficiency , characterized by the clinical triad of ophthalmoplegia , ataxia and confusion . it is defined pathologically by neuronal loss and hemorrhagic lesions in the paraventricular and periaqueductal grey matter . there seems to be a relation between the severity of neurological signs and extent of the underlying pathology ( 47 ) . animal models suggest similar brain changes in direct alcohol neurotoxicity and those produced by thiamine deficiency . these changes include shrinkage of frontal brain volume , loss of cells in the basal forebrain and hypofunction of hippocampal acetylcholine . thiamine deficiency also showed lesions in the diencephalon , which were not present in direct alcohol neurotoxicity ( 48 ) . other pure cases of thiamine deficiency ( as in cases of malnutrition and absorption disorders ) , without chronic and excessive alcohol consumption , show a low rate of progression to ks ( 49 ) . the wernicke s encephalopathy is likely to be the main underlying pathology in both ks and ard . the korsakoff syndrome is a long - term outcome of we and includes a syndrome of profound memory impairment , which is related to additional disruption to diencephalic and hippocampal circuitry . because of similar pathological substrates , we and ks are commonly referred to as the wernicke - korsakoff syndrome ( wks ) ( 2 ) . patients with wks demonstrate similar but more severe lesions in form of deficits in regional brain volumes ( mammillary bodies , thalamus , cerebellar hemispheres , and vermis ) than alcoholic patients without wks ( 47 ) . there have been suggestions that cases of ard are variants of the wks due to combination of heterogeneity in presentation of the wks along with a lack of distinct pathology for ard ( 50 ) . other reports suggest that ard and wks are distinct disorders with overlapping clinical profile ( 24 ) . cognitive and behavioral changes specific to alcohol use and ard have received limited interest and investigation . acute cognitive impairment can be seen in direct intoxication which impairs most cognitive skills and in excess , may lead to respiratory depression and stupor . long - term alcohol use may result in amnesia and difficulty in recall ( 43 ) . differing from other types of dementias , patients with ard are unlikely to demonstrate language impairments ( 12 , 24 ) ; however , intact confrontational naming has not been shown in all studies ( 15 ) . compared to alzheimer s dementia , the ard group performed better on confrontational naming , category fluency , general knowledge ( semantic tasks ) and verbal memory ( 15 , 51 ) . however , moderate alcohol drinking was shown to reduce likelihood of verbal memory impairment in one study ( 52 ) . in comparison with healthy controls , the ard groups performed poorly on visuo - spatial measures , including copying tasks and clock drawing . deficits on executive functions ( verbal abstract reasoning and letter fluency ) , working memory and motor speed have also been observed ( 15 , 51 ) . though smaller in their sample size , few studies have proposed that the clinical profile of ard reflects both cortical and subcortical pathology ( 52 ) . recent single photon emission ct study supported above findings by reporting hypometabolism in the frontal cortices , thalami and basal ganglia in ard cases ( 13 ) . remarked that it would be more apt to describe the chronic phase of wks as dementia - like deterioration / ard rather than severe and selective amnesia ( 53 ) . having comparatively spared implicit and procedural memories , patients typically have profound antegrade amnesia and impaired recall , with recall being better for more remote events ( 54 , 55 ) . in around 80 % of the patients suffering from ks / ard , executive deficits have been identified , mostly in the tasks assessing planning , higher - order organization , and cognitive flexibility ( 56 , 57 ) . the wernicke - korsakoff syndrome and early phase of ard are fluctuating and dynamic in their cognitive manifestations . unlike other dementias , ard has shown recovery after abstinence , even within a week , though further recovery of cognitive abilities can continue over several years ( 42 ) . this correlates with current neuroimaging evidence of at least partial structural and functional recovery from alcohol - related brain damage if abstinence is maintained . according to an animal study , the effects of thiamine deficiency ( increased perseverative behavior and spatial memory impairment ) are more persistent as compared to the effects of persistent ethanol exposure ( 59 ) . executive function , working memory , perceptual and motor impairments commonly endure following short - term abstinence , probably a reflection of compromised fronto - cortico - cerebellar functional networks ( 36 ) . the outcome and recovery rate of alcohol - related cognitive decline can be influenced by many factors like age , gender , education , chronicity , pattern of use , nutritional status and genetics . chronicity and severity of alcohol use has been highlighted to be associated with worsening of cognitive performance , and determines the rate and the extent of cognitive recovery ( 46 ) . cognitive impairment appears to be linked to the amount of recent use and duration of abstinence rather than lifetime alcohol consumption . binge drinking and multiple withdrawals may significantly exacerbate cognitive deficits ( 60 , 61 ) . greater cognitive impairment is seen in chronic and older drinkers and they are less likely to recover even after abstinence ( 42 ) . lower literacy level is associated with poor recovery over time , while females appear to be more prone to develop cognitive impairment despite lower intake ( 42 , 61 ) . family history of alcohol dependence may predispose to development of alcohol - related cognitive dysfunction , with impairment potentially predating alcohol misuse ( 42 ) . the cognitive impairment in ard is relatively non - progressive or even partially reversible in abstinent ex - drinkers ( 62 ) . different follow - up studies have demonstrated stabilization of cognitive and functional status in some domains for the ard group , as opposed to other forms of dementia ( 14 , 63 ) . abstinence of up to a year may show improvement in attention , working memory , problem solving and visuo - spatial functioning along with increased brain volume . however , impairments in areas of learning and short - term memory are more persistent ( 64 ) . assessment and diagnosis of ard and wksrequires high index of suspicion in a patient who has a history of long duration or heavy consumption of alcohol . a brief summary of assessment and investigations are highlighted in table 1 . due to varied types of presentation and no specific brain pathology , making a diagnosis of ardthe diagnostic and statistical manual of mental disorders may be helpful in diagnosing dementia due to use of alcohol . it requires the presence of memory impairment and ( inability to recall or to learn new information ) along with cognitive disturbances in form of either aphasia , apraxia , agnosia or / and executive dysfunctioning ( 11 ) . if ard is detected early enough , the effects may be reversed by abstinence . also , a healthy diet is essential to replace the deficient vitamins / minerals . although abstinence usually results in improvement in cognitive functions , it is achieved only after a long period , extending up to several months . a recent meta - analysis showed that cognitive profile tends to become normal only after 1 year of abstinence , while certain residual cognitive impairments may persist . different domains of cognition may improve over time , not necessarily together and to same degree . for example , the presence of visuospatial function deficits may be observed after several years of abstinence , which may be related to the decreased volume of the right parietal cortex ( 70 ) . parenteral thiamine should be administered immediately if any evidence of alcohol - related cognitive decline is present ( 31 ) . the wernicke s encephalopathy and wks may be reversed if diagnosed early ( 48 - 72 hours of the onset of symptoms ) and adequately treated with parenteral thiamine ( 71 ) . failure to administer adequate doses of thiamine may result in mortality in up to 20 % of we ( 66 ) , or progression to korsakoff syndrome and ard later on ( 72 ) . other vitamin and electrolyte deficiencies should also be corrected , especially magnesium and niacin . due to the damage caused by alcohol metabolism coupled with thiamine deficiency , adequate thiamine transport is affected at various sites including the blood - brain barrier . as the apoenzymes are also altered , they require higher concentrations of thiamine to work normally . thus a greater concentration of thiamine is required in the brain which the body is unable to achieve through oral supplementation . hence , intravenous thiamine administration of up to 1 g may be required in the first 24 hours for successful treatment of alcohol - related thiamine deficiency ( 73 ) . according to cochrane reviews , enough evidence is not available to guide the clinician on thiamine supplementation for prophylaxis or treatment of we and ard as to what dose should be given , for how long , through which route ( 74 ) . efns european federation of the neurological societies recommendation for suspected cases of we and wks is 200 mg of thiamine thrice daily , preferably intravenously ( 32 ) . until further studies are available , the following recommendations are based on available literature , to determine doses for thiamine supplementation in the prevention and treatment of we / wks ( 75 ) . patients with a definitive diagnosis should receive 200 - 500 mg intravenous thiamine thrice a day for 5 - 7 days . patients with suspected / high risk cases should be given prophylactic treatment with 100 - 200 mg intravenous thiamine thrice a day for 3 - 5 days . in both the cases , it should be followed by oral thiamine in doses of 100 mg thrice a day for 1 - 2 weeks , then 100 mg daily thereafter . lifestyle changes in form of exercise and healthy diet is also important . in cases with cognitive impairment , memantine , a low - affinity nmda receptor antagonist has also shown promise in improving cognition in ard , although these findings need to be replicated . a 12 - week study on patients with probable ard showed significant improvements on global cognition , quality of life and behavioral symptoms ( 76 ) . another memantine trial on wks patients also showed improvement in cognition ( word list recall , word list recognition , time orientation , drawing an interlocking pentagon and the total mini mental state examination - korean version ) of all the patients ( 77 ) . a study reported that rivastigmine improved ard in a dose 3 - 12 mg per day after two months of treatment ( 78 ) . not all patients with ard and neurocognitive impairment will recover or benefit from abstinence and other measures mentioned above . it is established that cognitive rehabilitation and neuropsychological training helps in slowing cognitive decline , and accelerates acquisition of new cognitive capabilities ( 79 ) . however , efficacy of cbt depends upon the relative integrity of certain brain regions particularly frontocerebellar and preserved cognition ( 80 ) . thus , cbt can not be effectively employed where cognition is severely impaired particularly memory and executive function ( 81 - 83 ) . these factors are motivation , participation in group therapy , self - efficacy and compliance with treatment . cognitive impairmentcognitive impairment also influences the degree of motivation , which is an essential prerequisite for effective management . thus , cognitive dysfunction influences management by determining the efficacy of treatment and the prognosis . cognitive remediation therapy based management programs have been investigated in very few studies in alcohol - dependent patients ( 82 , 84 ) with encouraging results . cognitive remediation program improves divided attention , alert capacities , working memory , and episodic memory along with improvement in other non - cognitive domains , especially psychological aspects ( well - being , self - esteem ) and craving ( 85 ) . in spite of recognition , focus on cognitive strategies for enhancing cognition is surprisingly less and more studies are needed to evaluate the benefits . the present diagnostic criteria for alcohol - related cognitive impairment focus only on alcohol amnesic syndrome and ard ( 8 ) . the two primary classification guidelines , the international classification of diseases , icd - 10 ( 9 ) and the diagnostic and statistical manual of mental disorders , dsm - 5 ( 10 ) also differ in description of ard . amnesic syndrome , according to icd - 10 ( f10 .6 ) is characterized by impairment of both recent and remote memory , with preservation of immediate recall . f10 .73 of icd - 10 classifies residual and late - onset psychotic disorder , characterized by changes of cognition and personality , induced by psychoactive substance , with subtype dementia . the dsm - 5 has included a specifier of substance use in the diagnostic criteria for major / mild neurocognitive disorders ( the term that has replaced dementia in dsm - 5 ) . major / mild neurocognitive disorders supersede the diagnosis of alcohol - induced persisting dementia and alcohol - induced amnestic disorder , although these terms still are in use . many clinicians prefer this term to ard because it represents the heterogeneity of clinical features more appropriately , the stigma associated with the term dementia and alcohol gets avoided , and ard s non - progressive nature gets distinguished from other degenerative disorders . the diagnostic and statistical manual of mental disorders , 4th edition ( dsm - iv ) included a category for alcohol - induced persisting dementia . it was characterized by neurocognitive decline associated with alcohol use , in the absence of other causes of dementia ( 11 ) . the wernicke - korsakoff syndrome ( wks ) is described in the dsm - iv under alcohol - induced persisting amnestic disorder . oslin refined the diagnostic criteria for ard by including duration and severity of alcohol consumption and a minimum abstinence time , for ahe expected this classification would bring more clarity and stimulate further research in this area ( 12 ) . even till now , only a few studies have adopted these criteria and they still need research for being conclusive ( 13 - 15 ) . it can be concluded that presently , clinical judgment guides the current diagnostic criteria for ard . this has prognostic significance as ard is considered less progressive than other forms of dementias ( 7 ) . presently , most of the cases of dementia are attributed to alzheimer s disease , vascular causes and lewy body dementia . alcohol - related dementia is largely overlooked or seen as a comorbid factor ( 7 ) . the incidence and prevalence of ard varies across studies as there are no defined diagnostic criteria . variations may also be due to the differences in the socio - demography of study samples . a review indicated a high prevalence of alcohol abuse in dementia patients ( 9 % to 22 % ) and 10 % - 24 % prevalence of dementia in alcohol abusers ( 16 ) . it is interesting to note that the prevalence data of ard is from the cohort that consists mainly of today s younger and middle - aged generation . thus , it might be predicted that ard rates would be even higher in the future , given that chronic alcohol misuse will continue . hence , it becomes important for the studies to include those less than 60 years of age ( 16 ) . an english epidemiological study of younger - onset dementia ( onset before 65 years ) found 10 % rates of ard ( 17 ) . an australian analysis demonstrated that ard was found in 1.4 % of all patients with diagnosed dementia but its prevalence was 22 % in cases who had onset before 65 years ( 18 ) . a study found a direct association between cognitive decline , and chronicity and severity of alcohol use ( 19 ) . prevalence rates of ard in hospitals and clinics have been reported to account for 10 % to 24 % of all dementias subtypes ( 16 , 20 ) . reports from neurology and memory clinics suggest lower rates of ard in dementia cases , around 3 % - 5 % , indicating less referral to these centers ( 21 , 22 ) . older studies have suggested that of all cases of dementia , ard accounts to approximately 10 % ( 23 ) . in a review by smith , heavy use of alcohol was a contributory factor in approximately 24 % cases of dementia ( 24 ) . an ongoing controversy concerns the amount of alcohol that predisposes an individual for development of ard . united kingdom s department of health limits daily alcohol consumption to 2 - 3 units for women and 3 - 4 units for men . a number of studies have found a j - shaped or a u - shaped relationship between the amount and consequences of alcohol use on cognitive impairment . light - to moderate alcohol consumption is associated with a lower risk of dementia ( 25 ) while heavy drinking is associated with a higher risk ( 26 ) . a meta - analysis found that small amounts of alcohol may protect against alzheimer s dementia ( 27 ) while others suggest that it is protective against all forms ( 28 ) . however , a recent study concluded that even heavy regular drinking is not a direct cause of cognitive impairment in later life ( 29 ) . studies have shown that ard patients are mostly males , unmarried , have comorbid mental and physical conditions , likely to be identified through hospital admissions , are socially isolated , and do not have social support ( 14 , 30 ) . the prevalence rate estimates from post - mortem studies are 1 % - 2 % of the general population and 10 % of alcohol consumers ( 31 , 32 ) . netherlands had a prevalence of 48 per 100,000 ( 33 ) , while incidence rates of 8 per 100,000 were estimated in scotland in 1995 ( 34 ) . a study of hospital admissions identified the korsakoff syndrome ( ks ) and wernicke s encephalopathy ( we ) cases to be 0.05 % and 0.03 % of all admissions , respectively ( 18 ) . the evidence from neuroimaging , neuropathological reports and autopsy evaluations suggest some degree of brain pathology in individuals diagnosed with an alcohol related disorder ( 35 ) . volume shrinkage , altered glucose metabolism and perfusion along with evidence of markedly decreased neuron density are commonly reported . computed tomography ( ct ) scans showed wider cerebral sulci and larger ventricles suggestive of atrophy ( 38 ) . the evidence of neuro - circuit disturbances is seen in form of significant loss of white matter ( most prominent in the prefrontal cortex , cerebellum and corpus callosum ) on functional imaging . neuronal loss is also noted in the superior frontal association cortex , cerebellum and hypothalamus ( 2 , 39 ) . greater cognitive impairment has been associated with multiple and repeated withdrawal due to greater neuronal damage . a study showed a greater degree of cognitive impairment in patients undergoing two or more detoxifications compared with those with one or none ( 40 ) . a study found fewer structural brain changes in treatment naive patients compared to clinical patients undergoing detoxification ( 41 ) . it is postulated that brain damage worsens with repeated withdrawals , which may be associated withhowever , whether these changes are permanent or not and whether they relate to neurotoxicity in isolation , yet remains to be established . alcohol - induced brain injury may be attributed to a direct neurotoxic effect of alcohol , oxidative stress , excitotoxicity , apoptosis , disruption of neurogenesis and mitochondrial damage ( 42 ) . it is proposed that repeated binge drinking and withdrawal facilitates neuronal injury by glutamate - induced excitotoxicity , mediated by upregulated n - methyl - d - aspartate receptors . this leads to increased intracellular calcium , which mediates oxidative stress , along with loss of cholinergic muscarinic receptors . dose related damage has been observed in the hippocampus , hypothalamus , and cerebellum in animal studies ( 43 , 44 ) . cholinergic neurotransmitter system ( particularly in basal forebrain ) , implicated in attention , learning and memory also appears to be impacted . imaging studies of isolated cases of uncomplicated alcoholic individuals ( without any nutritional deficiency , hepatic failure , brain injury ) have confirmed structural abnormalities , including changes to the corpus callosum , pons , and cerebellum ( 45 ) . abstinence results in improvement in motor abilities and cognition , and is accompanied by reversal of white matter shrinkage ( 45 , 46 ) . restoration of myelination and axonal integrity is the chief mechanism thought to be behind recovery from white matter damage ( 46 ) . this leads to a hypothesis that ard is primarily due to thiamine ( vitamin b1 ) deficiency . also , because of poor dietary nutrition , alcohol users are at a higher risk of thiamine deficiency ( 31 ) . the wernicke s encephalopathy is an acute neurological disorder , precipitated by thiamine deficiency , characterized by the clinical triad of ophthalmoplegia , ataxia and confusion . it is defined pathologically by neuronal loss and hemorrhagic lesions in the paraventricular and periaqueductal grey matter . there seems to be a relation between the severity of neurological signs and extent of the underlying pathology ( 47 ) . animal models suggest similar brain changes in direct alcohol neurotoxicity and those produced by thiamine deficiency . these changes include shrinkage of frontal brain volume , loss of cells in the basal forebrain and hypofunction of hippocampal acetylcholine . thiamine deficiency also showed lesions in the diencephalon , which were not present in direct alcohol neurotoxicity ( 48 ) . however , other pure cases of thiamine deficiency ( as in cases of malnutrition and absorption disorders ) , without chronic and excessive alcohol consumption , show a low rate of progression to ks ( 49 ) . the wernicke s encephalopathy is likely to be the main underlying pathology in both ks and ard . the korsakoff syndrome is a long - term outcome of we and includes a syndrome of profound memory impairment , which is related to additional disruption to diencephalic and hippocampal circuitry . because of similar pathological substrates , we and ks are commonly referred to as the wernicke - korsakoff syndrome ( wks ) ( 2 ) . patients with wks demonstrate similar but more severe lesions in form of deficits in regional brain volumes ( mammillary bodies , thalamus , cerebellar hemispheres , and vermis ) than alcoholic patients without wks ( 47 ) . there have been suggestions that cases of ard are variants of the wks due to combination of heterogeneity in presentation of the wks along with a lack of distinct pathology for ard ( 50 ) . other reports suggest that ard and wks are distinct disorders with overlapping clinical profile ( 24 ) . cognitive and behavioral changes specific to alcohol use and ard have received limited interest and investigation . acute cognitive impairment can be seen in direct intoxication which impairs most cognitive skills and in excess , may lead to respiratory depression and stupor . long - term alcohol use may result in amnesia and difficulty in recall ( 43 ) . differing from other types of dementias , patients with ard are unlikely to demonstrate language impairments ( 12 , 24 ) ; however , intact confrontational naming has not been shown in all studies ( 15 ) . compared to alzheimer s dementia , the ard group performed better on confrontational naming , category fluency , general knowledge ( semantic tasks ) and verbal memory ( 15 , 51 ) . however , moderate alcohol drinking was shown to reduce likelihood of verbal memory impairment in one study ( 52 ) . in comparison with healthy controls , the ard groups performed poorly on visuo - spatial measures , including copying tasks and clock drawing . deficits on executive functions ( verbal abstract reasoning and letter fluency ) , working memory and motor speed have also been observed ( 15 , 51 ) . though smaller in their sample size , few studies have proposed that the clinical profile of ard reflects both cortical and subcortical pathology ( 52 ) . recent single photon emission ct study supported above findings by reporting hypometabolism in the frontal cortices , thalami and basal ganglia in ard cases ( 13 ) . remarked that it would be more apt to describe the chronic phase of wks as dementia - like deterioration / ard rather than severe and selective amnesia ( 53 ) . having comparatively spared implicit and procedural memories , patients typically have profound antegrade amnesia and impaired recall , with recall being better for more remote events ( 54 , 55 ) . in around 80 % of the patients suffering from ks / ard , executive deficits have been identified , mostly in the tasks assessing planning , higher - order organization , and cognitive flexibility ( 56 , 57 ) . the wernicke - korsakoff syndrome and early phase of ard are fluctuating and dynamic in their cognitive manifestations . unlike other dementias , ard has shown recovery after abstinence , even within a week , though further recovery of cognitive abilities can continue over several years ( 42 ) . this correlates with current neuroimaging evidence of at least partial structural and functional recovery from alcohol - related brain damage if abstinence is maintained . according to an animal study , the effects of thiamine deficiency ( increased perseverative behavior and spatial memory impairment ) are more persistent as compared to the effects of persistent ethanol exposure ( 59 ) . executive function , working memory , perceptual and motor impairments commonly endure following short - term abstinence , probably a reflection of compromised fronto - cortico - cerebellar functional networks ( 36 ) . the outcome and recovery rate of alcohol - related cognitive decline can be influenced by many factors like age , gender , education , chronicity , pattern of use , nutritional status and genetics . chronicity and severity of alcohol use has been highlighted to be associated with worsening of cognitive performance , and determines the rate and the extent of cognitive recovery ( 46 ) . cognitive impairment appears to be linked to the amount of recent use and duration of abstinence rather than lifetime alcohol consumption . binge drinking and multiple withdrawals may significantly exacerbate cognitive deficits ( 60 , 61 ) . greater cognitive impairment is seen in chronic and older drinkers and they are less likely to recover even after abstinence ( 42 ) . lower literacy level is associated with poor recovery over time , while females appear to be more prone to develop cognitive impairment despite lower intake ( 42 , 61 ) . family history of alcohol dependence may predispose to development of alcohol - related cognitive dysfunction , with impairment potentially predating alcohol misuse ( 42 ) . the cognitive impairment in ard is relatively non - progressive or even partially reversible in abstinent ex - drinkers ( 62 ) . different follow - up studies have demonstrated stabilization of cognitive and functional status in some domains for the ard group , as opposed to other forms of dementia ( 14 , 63 ) . abstinence of up to a year may show improvement in attention , working memory , problem solving and visuo - spatial functioning along with increased brain volume . however , impairments in areas of learning and short - term memory are more persistent ( 64 ) . assessment and diagnosis of ard and wks requires high index of suspicion in a patient who has a history of long duration or heavy consumption of alcohol . a brief summary of assessment and investigations are highlighted in table 1 . due to varied types of presentation and no specific brain pathology , making a diagnosis of ardthe diagnostic and statistical manual of mental disorders may be helpful in diagnosing dementia due to use of alcohol . it requires the presence of memory impairment and ( inability to recall or to learn new information ) along with cognitive disturbances in form of either aphasia , apraxia , agnosia or / and executive dysfunctioning ( 11 ) . although abstinence usually results in improvement in cognitive functions , it is achieved only after a long period , extending up to several months . a recent meta - analysis showed that cognitive profile tends to become normal only after 1 year of abstinence , while certain residual cognitive impairments may persist . different domains of cognition may improve over time , not necessarily together and to same degree . for example , the presence of visuospatial function deficits may be observed after several years of abstinence , which may be related to the decreased volume of the right parietal cortex ( 70 ) . parenteral thiamine should be administered immediately if any evidence of alcohol - related cognitive decline is present ( 31 ) . the wernicke s encephalopathy and wks may be reversed if diagnosed early ( 48 - 72 hours of the onset of symptoms ) and adequately treated with parenteral thiamine ( 71 ) . failure to administer adequate doses of thiamine may result in mortality in up to 20 % of we ( 66 ) , or progression to korsakoff syndrome and ard later on ( 72 ) . other vitamin and electrolyte deficiencies should also be corrected , especially magnesium and niacin . due to the damage caused by alcohol metabolism coupled with thiamine deficiency , adequate thiamine transport is affected at various sites including the blood - brain barrier . as the apoenzymes are also altered , they require higher concentrations of thiamine to work normally . thus a greater concentration of thiamine is required in the brain which the body is unable to achieve through oral supplementation . hence , intravenous thiamine administration of up to 1 g may be required in the first 24 hours for successful treatment of alcohol - related thiamine deficiency ( 73 ) . according to cochrane reviews , enough evidence is not available to guide the clinician on thiamine supplementation for prophylaxis or treatment of we and ard as to what dose should be given , for how long , through which route ( 74 ) . efns european federation of the neurological societies recommendation for suspected cases of we and wks is 200 mg of thiamine thrice daily , preferably intravenously ( 32 ) . until further studies are available , the following recommendations are based on available literature , to determine doses for thiamine supplementation in the prevention and treatment of we / wks ( 75 ) . patients with a definitive diagnosis should receive 200 - 500 mg intravenous thiamine thrice a day for 5 - 7 days . patients with suspected / high risk cases should be given prophylactic treatment with 100 - 200 mg intravenous thiamine thrice a day for 3 - 5 days . in both the cases , it should be followed by oral thiamine in doses of 100 mg thrice a day for 1 - 2 weeks , then 100 mg daily thereafter . lifestyle changes in form of exercise and healthy diet is also important . in cases with cognitive impairment , memory training techniques along with social supportmemantine , a low - affinity nmda receptor antagonist has also shown promise in improving cognition in ard , although these findings need to be replicated . a 12 - week study on patients with probable ard showed significant improvements on global cognition , quality of life and behavioral symptoms ( 76 ) . another memantine trial on wks patients also showed improvement in cognition ( word list recall , word list recognition , time orientation , drawing an interlocking pentagon and the total mini mental state examination - korean version ) of all the patients ( 77 ) . a study reported that rivastigmine improved ard in a dose 3 - 12 mg per day after two months of treatment ( 78 ) . not all patients with ard and neurocognitive impairment will recover or benefit from abstinence and other measures mentioned above . it is established that cognitive rehabilitation and neuropsychological training helps in slowing cognitive decline , and accelerates acquisition of new cognitive capabilities ( 79 ) . however , efficacy of cbt depends upon the relative integrity of certain brain regions particularly frontocerebellar and preserved cognition ( 80 ) . thus , cbt can not be effectively employed where cognition is severely impaired particularly memory and executive function ( 81 - 83 ) . these factors are motivation , participation in group therapy , self - efficacy and compliance with treatment . cognitive impairmentcognitive impairment also influences the degree of motivation , which is an essential prerequisite for effective management . thus , cognitive dysfunction influences management by determining the efficacy of treatment and the prognosis . cognitive remediation therapy based management programs have been investigated in very few studies in alcohol - dependent patients ( 82 , 84 ) with encouraging results . cognitive remediation program improves divided attention , alert capacities , working memory , and episodic memory along with improvement in other non - cognitive domains , especially psychological aspects ( well - being , self - esteem ) and craving ( 85 ) . in spite of recognition , focus on cognitive strategies for enhancing cognition is surprisingly less and more studies are needed to evaluate the benefits . considering the growing proportion of ageing population and rise in per capita alcohol consumption , future generations are expected to see a disproportionate increase in ard and neurocognitive impairment . presently , there are dilemmas over the diagnosis of independent ard . screening tests like the michigan alcohol screening test combined with neuropsychological tools such as mmse and moca can help in early detection of these cases . there is a need to develop tools for assessment of alcohol - related cognitive impairment . patients with ard are often hospitalized for other physical comorbidities and one should be vigilant enough to screen , identify and manage it at the same time . internationally , the challenges of developing evidence - based guidelines for social work practice in dementia care are generating a lot of interest . the development of future practice guidelines for ard should be modeled on a joint health and social care perspective . legislative reforms in the use of alcohol similar to that used in the fight against tobacco are much needed . therefore , ard and alcohol - related neurocognitive impairment is an under - recognized problem and urgent action is needed to prevent this ever increasing epidemic .\noutput:\n" }, { "from": "agent", "value": "contextalcohol consumption has escalated rapidly in many countries over the past decade . evidence suggests a correlation between alcohol use and cognitive decline . we have systematically reviewed the concept and controversies , epidemiology , nosology , neuropathology and neurobiology , neuropsychology and management updates of alcohol - related dementia ( ard ) in this paper.evidence acquisitionwe retrieved papers for this review by searching the pubmed database for terms alcohol and dementia , alcohol and cognitive impairment , and alcohol and wernicke - korsakoff mentioned in the title of the published papers . a total of 131 studies showed up . appropriate studies were shortlisted and included ( n = 72 ) . cross - references if relevant were considered from the selected studies . eligible articles were fully read by the authors and the results were compiled.resultsthe prolonged and excessive use of alcohol may lead to structural and functional brain damage , leading to ard . the cognitive deficits are most frequently observed in domains of visuospatial functions , memory and executive tasks , with a potential of partial recovery if abstinence is maintained . however , there are doubts regarding the etiopathogenesis , nosological status , prevalence and diagnostic criteria for ard , due to difficulty in assessment and various confounding factors.conclusionswith growing cohort of young and middle - aged people , there is a probable risk of upsurge of ard . presently , there are dilemmas over the diagnosis of independent ard . thus , there is a need to develop evidence - based guidelines for diagnosis and management of ard through further systematic studies ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: in developed countries , people aging 65 and older constitute approximately 20 % of the population and are the fastest - growing segment of the population . with this growing aging population , being relocated to an assisted living facility can result in functional and health disturbances and worsen quality of life in elders . this may be attributed to or worsened by lack of regular physical activity . appropriate exercise programs may be an important component of quality of life in this group of transitional frail elders . previous studies suggest that participation in a regular exercise program can be an effective intervention to reduce / prevent a number of functional declines associated with aging . in thisregard , current guidelines point out the importance of aerobic exercise in the maintenance and improvement of various aspects of cardiovascular function and health and strength training in the attenuation of muscle strength declines associated with normal aging . moreover , considering that cardiovascular diseases ( cvd ) are the major cause of death in the elders , sustaining older adults ' ability to live independently as well as reducing blood pressure ( bp ) , plasma lipoprotein lipid profiles , and body weight via healthy lifestyles interventions are very important goals of public health , geriatrics , and gerontology . although there is sufficient data showing that regular physical activity ( pa ) is associated with improvements in cardiovascular health among older adults , additional information is necessary concerning the effectiveness of different types of heath promotion and exercise interventions . furthermore , regarding that a number of studies have indicated that both morphologic and functional adaptations can decrease even after short detraining periods , it seems of interest to know whether the heath promotion interventions benefits are maintained when detraining occurs , due to unexpected causes such as , illness , vacations , or others . in fact , despite evidence of physiological decline during detraining , there is not enough data suggesting how long the beneficial effects of training are maintained , how this affects the health related quality of life ( hrqol ) and how functional fitness changes following the cessation of exercise intervention in institutionalized elders . most studies of detraining in elders have examined the effects after exercise intervention and focused on different performance measures of physical function , resembling the effects on functional fitness response . while some studies have shown similar decreases in strength , aerobic endurance , and agility / dynamic balance , others have showed that increases in muscle strength after training can be maintained after 24 weeks , 27 weeks , and 31 weeks of detraining in older adults . according to the literature the initial levels of physical activity and functional capacity , gender differences , duration of the detraining period , age , and the evaluation method used could be possible explanations for the discrepancy between studies . few studies have reported detraining evidence after different types of interventions and those have not addressed hrqol and cardiovascular health variables . therefore , the purposes of this study were to investigate the effects of 1 year of 3 different health intervention programs ( aerobic training , strength training , and health education ) on physical fitness , pa patterns , cardiovascular health variables , and hrqol . subjects were recruited from 8 long - term care institutions ( nursing homes ) randomly selected in the oporto area ( north of portugal ) . two hundred nineteen elderly subjects aging 66 to 92 volunteered to participate in this study . at the screening , participants completed a health history questionnaire to record past and present conditions and medication , as well as a sociodemographics and years of institutionalization questionnaire . participants were considered eligible for inclusion if they had scored 24 or more on the mini - mental state examination ( without mental dysfunction ) with a barthel index 40 or more ( without several dependence ) and also if they were not engaged in regular exercise of moderate to vigorous intensities for 20 minutes or more at least twice a week in the past 3 years . participants were excluded if they had any medical or physical limitations for testing or training and were without medical assistance or control drugs . there were 11 elders with osteoporosis , 24 with diabetes , 7 with respiratory illness , 19 with hypertension , 44 with hypercholesterolemia , and 5 with arthritis . in general , each subject received 6 different drugs ( range 411 ) daily , including supplements such as calcium , vitamin b , diuretics , laxatives , heart drugs , antihypertensive , antidepressants , and painkillers . before conducting the study , all participants received a complete explanation of the purpose , risks , and procedures of the investigation and gave their written consent . the investigation was in full compliance with the helsinki declaration of 1975 , as revised in 2004 . the elderly subjects provided written informed consent before the study . due to recruitment implications according to infrastructures available on each institution , therefore , the 185 eligible subjects , from institutions registered in this study , were allocated into four groups : aerobic exercise program ( at ; n = 49 ) , strength training program ( st ; n = 37 ) , health education program ( he ; n = 52 ) , and control group ( cg ; n = 47 ) . however , after randomization , 19 participants of the st group volunteered for the control group , potentially reducing the sample size of st program ( n = 18 ) . data were collected by trained investigators , using always the same protocol , for all variables at baseline ( m1january 2006 ) , after the 1 - year control period ( m2february of 2007 ) , and , finally , after 3 months of detraining ( m3may of 2007 ) . the 1 - year exercise interventions were held twice a week , each session lasted 3040 minutes and were supervised by a qualified and trained instructor . briefly , at sessions consisted of 10 minutes warm - up , followed by 20 minutes of aerobic workout using continuous walking and dancing using rhythmic and large muscle groups movements and ended with a 810 minutes of cool - down . in the first month , duration was increased from 20 to 30 minutes with an intensity of 2 - 3 of the adapted borg rating of perceived exertion scale ( rpe ) . subsequently , the intensity was gradually increased up to 4 - 5 in the adapted borg rpe . moreover , in order to evaluate the intensity of at and detect workloads that rise above moderate intensity , the talk test was also used . st consisted of 2 sets of 6 exercises ( each with 8 to 12 repetitions ) specifically directed to the development of endurance , muscle mass , and strength of the quadriceps ( using leg press and leg extension ) , hamstrings ( using seated leg curl ) , trunk and arms ( using women 's double chest , lateral raise , and overhead press ) , and abdominal wall ( using an abdominal machine ) . movements were repeated approximately every 6 seconds , with 2 seconds for each lifting movement ( concentric muscle action ) and 4 seconds for each lowering movement ( eccentric muscle action ) . during the first two weeks the training intensity was 4550 % of 1rm in order to promote adaptation to exercise routine . from third week , the load was raised to 6065 % of 1 rm and maintained until the final of the program . the 1 rm tests were performed each 15 days until the first month and then each 4 weeks until the end of the program . for the elderlyreceiving he , health professionals provided encouragement and reinforcement of the importance about pa without providing any exercise protocols to follow . these interventions covered broad domains of health care management , well - being and social awareness related to elderly people 's health , and health care . health care management was primarily related to nutritional advice , management of bone , and joint - related illness ( e.g. , joint pain , arthritis , and back pain ) as well as other illnesses ( e.g. , diabetes , high blood pressure , etc . ) . normal activities of daily living were maintained during detraining , but none of the subjects participated in any supervised exercise program . in order to control the absence of any exercise or other health - promotion interventions , they were contacted face to face by the health professionals of the institutions . subjects allocated into cg ( n = 66 ) were instructed not to change their daily living pa routines or dietary patterns during the course of the study and not to carry out any supervised pa and were informed that they would receive intervention after the end of the study . after the observation period , subjects randomized to the cg were invited to participate in specific exercise programs designed to seniors undergoing in the institution . body mass index ( bmi ) measure was used as an estimate of body composition . body height was measured to an accuracy of 1 cm , with the subject in an upright position with a standard stadiometer . body weight was measured to the nearest 0.1 kg , with subjects lightly dressed and in stocking feet . the percentage of body fat was evaluated with the bioelectrical impedance bodystat it 's the same that stella . this is an alternative easy and noninvasive method to specifically assess the percentage of fat through a low - intensity electric current that runs through the subject 's body . the average values of body fat were between 17 and 21 % for men and 22 and 31 % for women . older adults ' perceptions of their general health were assessed using the medical outcomes study 36 - item short - form health studythe mos sf - 36 is a generic measure of health condition including 36 items covering 8 dimensions : physical functioning ( pf10 items ) , body pain perception ( bp2 items ) , general health ( gh5 items ) , vitality ( vt4 items ) , social functioning ( sf2 items ) , emotional role limitations ( eh3 items ) , limitations due to physical health ( ph ) , and mental health ( mh5 items ) scores are summarized into two main domains ( physical and mental component ) and ranged from 0 ( worst possible quality of life ) to 100 ( best possible quality of life ) . as suggested by ware and sherbourne , the instrument was applied by an interview and scores were calculated using the methods set out by the authors . physical fitness was evaluated using the functional fitness test ( fft ) , that consists of 6 validated items ( and one alternative ) designed to assess the physical mobility of older adults . participants were asked to sit on a 43 - cm - high chair with arms crossed at the wrists and held against the chest . stand ups as possible within 30 s. the score was the total number of stands executed through the full range of motion within 30 s. the reliability of this strength test is high ( r = 0.92 ) . participants performed as many biceps curls as possible in 30 s , using a dumbbell . the score was the total number of handweight curls performed through the full range of motion in 30 s. the arm curl test has good relative reliability across trials ( r = 0.80 ) . the score was the best distance achieved between the extended fingers and the tip of the toe , measured to the nearest 0.5 cm . the reliability of the chair sit - and - reach test is high ( r = 0.96 ) . the score was the shortest distance achieved between the extended middle fingers , measured to the nearest 0.5 cm . agility / dynamic balance was assessed using the 8 - foot up - and - go test . the score was the shortest time to rise from a seated position , walk 2.44 m ( 8 ft ) , turn , and return to the seated position , measured to the nearest 1 / 10th s. the 8 - foot up - and - go test has showed a high test - retest reliability of 0.90 . participants were asked to walk as fast as possible for 6 min with verbal encouragement given at 30 - second intervals . the score was the total distance walked in 6 min along a 45.72 - meter rectangular course , which was marked every 4.57 m. the reliability of this test is high ( r = 0.91 ) . all test stations were organized in a circuit and the same conditions were maintained for each test at all testing periods , after a demonstration by the tester , a practice trial of 2 repetitions , followed by 1 test trial . full detailed information on test administration and protocols can be found in the work of rikli and jones . resting blood pressure ( bp ) was measured with the dinamap vital signs monitor ( critikon ; ge medical systems , milwaukee , wi ) , using the right arm . after being 15 minutes at supine rest in a quiet , temperature - controlled room , bp measurements were taken with the subjects seated in an upright position with the arm comfortably placed at heart level . measurements of the diastolic ( dbp ) and systolic ( sbp ) bps were taken within a 1 - minute break , by the same investigator . the measurements were performed between 8:00 am and 11:00 am , at least 30 minutes after meal . subjects were deemed to be hypertensive where their sbp was 140 mmhg and their dbp was 90 mmhg or they were on current antihypertensive drug treatment . a venous blood sample for biochemical assays was withdrawn from the antecubital vein after an overnight fast for measurement of fasting blood glucose and lipid concentrations ( high - density lipoprotein ( hdl ) , low - density lipoprotein ( ldl ) , triglycerides ( trigs ) and total cholesterol ( tc ) ) . samples were stored at 80c and analysed using the cholesterol esterase / oxidase enzymatic method , and triglyceride was analysed using the lipase / glycerol kinase / glycerol phosphate oxidase enzymatic method . an accelerometer mti actigraph was used before and after the intervention as an objective measure of daily pa over seven consecutive days . all participants were instructed about how to carry out the accelerometer that should be placed in a small nylon pouch and firmly adjusted at the person 's waist using an elastic belt over the hip . a data sheet was given to each senior participant who was instructed to record the time when the monitor was attached in the morning and detached in the evening and every time he or she performed any restricted activities like showering and swimming . these data , summarized as counts per day , were considered to be complete if 70 % of the day ( 1000 minutes ) was recorded for at least 4 of the 5 week days , and 2 days of the weekend . for the present study , the time duration or sampling period was set at 1 minute and the output was expressed as counts per minute ( countsmin ) . then , for the statistical analysis we calculated the mean of the counts by hour . pa was also expressed as the average counts per hour ( countsh ) over the 7 days . to the best of our knowledge , there are no appropriate count cut - points that represent meaningful intensity categories ( sedentary , moderate , and vigorous ) in older adults , therefore , in the current study , activity intensities were based according to the research findings of freedson et al . . data were analysed with spss software ( version 17.0 ) . the level of significance was set at p .05 . shapiro - wilk test was used to ascertain on all variables the normality of data distributions . the delta ( ) was calculated via the standard formula : = { ( posttest scorepretest score ) / pretest score } . weight outcomes were assessed by three different moments : 1 change from baseline to 1 year , 2 weight change from 1 year to 15 months , and also 3 weight change from baseline to 15 months . differences within the group in pre - versus postintervention and detraining values were performed by one - way analysis of variance ( anova ) . scheffe was used for post hoc comparisons . repeated measures and multivariate analyses of variance were used to examine differences within and between groups over time . when f values were significant , post hoc means comparisons were analysed with least significant different comparisons test . of the 185 participants who submitted the initial assessment , 148 ( 75 % ) participants completed pre - and postintervention and testing protocols . however , of these 148 , only 137 completed the 15 - month assessments ( including the detraining period ) . during the study , 25 persons died , 11 moved out of the institutions , and 12 dropped out from the programs ( figure 1 ) . overall compliance with the exercise prescription was 78 % in the at program and 60 % in the st program . there were no differences among groups at baseline in relevant characteristics such as age , medical condition , bmi , fitness score , hrqol , and pa . table 1 also shows that after the intervention , no significant changes were observed in the control group , although the trend indicated an increase in sbp , tc , and glucose levels . however , exercise interventions groups showed a significant increase in the pa levels and improve cardiovascular variables ( glucose , tc levels , and blood pressure ) . after the detraining , we did not observe significant change in cardiovascular variables and pa , which remains significantly higher than baseline values . our results showed that the biggest improvements of fft were in the strength and flexibility tests in the st group and in the aerobic endurance , lower body strength , and agility / dynamic balance in the at group . the control group significantly decreases the agility / dynamic balance and the lower body strength and flexibility . the implications of detraining in our subjects are most evident at lower - extremity body although , the upper body strength also decreased in the st , nevertheless the values remained higher than before training . only the agility / dynamic balance , particularly in the at group , reverted to values lower than baseline , but not statistically significant . the overall results of this one - year health - promotion interventions study in institutionalized older subjects were the improvement in physical fitness , hrqol , and cardiovascular variables , particularly in the exercise intervention groups . after the detraining , agility / dynamic balance was affected and also components from lower - extremity body , as strength and flexibility . the data also revealed a significant increase in the pa levels after intervention and declining with detraining , but remaining significantly higher than baseline values . in accordance with the actual evidence , our results showed a major improvement in strength and flexibility in the st group and a significant improvement in lower body strength , aerobic endurance , and agility / dynamic balance in the at group . although , previous investigations have demonstrated an age - related functional decline , these improvements are not unexpected , because , as explained earlier in the literature the specificity of the training exists even in older subjects . further , our results also confirm the hypothesis that one year of moderate intensity exercise interventions ( twice per week ) is associated with several important cardiovascular risk factors and function , namely , the declining of bp and also benefits in the hrqol . simons and andel showed that walking program is able to increase the aerobic endurance and flexibility and improve the performance of elders in the sit - and - reach test . in our study , the agility / dynamic balance improvements , particularly in the at , might be related to increased lower body strength observed during the training period . according to marzilli et al . additionally , specific balance activities used in the present study may possibly have stimulated additional benefits . it was not possible to establish the independent effect of exercise programs on flexibility , because all of the programs also included flexibility exercises . state that the at , as well as being used in the elderly , has excellent health benefits , increasing cardiofitness and strength and reduces the risk factors associated with cvd and metabolic diseases . however to promote and maintain physical health and functional independence is also necessary to preserve and increase muscle strength through st . st compensates the loss of muscle and bone mass associated with aging , reducing the risk of fractures , and otherwise maintains the functionality and flexibility postural stability , thus reducing the risk of falling . according to our results , we observed that st was the most effective way to improve plasma lipoprotein lipid profiles and also improve insulin action , which results in one significant decrease of glucose , triglycerides , hdl - cholesterol and tc . we observed , as durstine et al . suggested , that exercise training lasting longer than 12 weeks is more likely to increase plasma hdl cholesterol and triglycerides in a dose - dependent manner . in this way , pa is a most appropriate intervention in a collaborative approach to the management of abnormal blood lipids and should be undertaken at moderate to high intensity , 5 to 7 days / week for at least 30 min / day . furthermore , to achieve changes in lipids or weight , the majority of the studies indicate that changing dietary behaviour as well as performing vigorous exercises is fundamental and yields the best effects . although the mechanisms underlying the lowering effect of exercise on bp are not fully understood , the recent acsm and aha guidelines recommend light - to moderate - intensity lifestyle physical activities to optimize health , and moderate or high - intensity exercise may be required to produce adaptations in the cardiovascular system and in cvd risk factors . these changes are of importance since hypertension , a common disease of older individuals , is associated with an increased incidence of all - cause and cvd mortality and morbidity such as , stroke , coronary heart disease , and renal failure . barger and muldoon concluded that hypertensive labeling was associated with poorer hrqol as measured by global self - rated health . kuo et al . in a longitudinal study concluded that hypertension and diabetes were associated with a significantly faster pace of decline on the perceived hrqol and elders with diabetes had a faster pace of decline in activities daily living functioning than nondiabetic subjects . many studies have examined the effects of exercise on several cardiovascular risk factors , depending on the type , intensity , duration of exercise , and participants ' age and functional status and different methodologies used to evaluate older population , and results have been discordant . in fact these positive cardiovascular health changes are usually more associated with reductions of body weight and dietary fat reductions . although our subjects were instructed to maintain their normal dietary routines throughout the protocol period , this was not strictly controlled . it is possible that the participants in our study increased their energy intake in response to the energy demands of exercise training . the data available in the literature generally support the conclusion that older adults improve their plasma lipoprotein lipid profiles with pa , increase in plasma hdl cholesterol levels , and have diminutions in triglyceride and cholesterol levels . nevertheless , these changes may be secondary to training - induced reductions in body fat scores . . showed that the existence of greater amounts of pa and of low intensity is associated with a more favorable lipid profile in the elderly . we also observed that higher bmi is also associated with reduced pa and functional capacity , suggesting that the risk of obesity may be explained partially by the adverse effects of inactivity . while weight loss has been shown to decrease multiple cardiovascular risk factors , the direct benefit of weight reduction on cvd risk remains unproven and unclear . our data adds evidence to the role of pa as prevention to the cvd risk factor in elders , which is in accordance with the expected effects of health promotion intervention with pa . overall , the studies related to the risk of cvd and pa indicate that the relationship is causal and most likely to provide evidence of a dose - response relationship , showing that there is a decrease in cvd mortality in subjects with a more active lifestyle . these results have been demonstrated in a variety of populations and using a diversity of methods of assessment of pa . this sustains the need for more studies with different protocols and considering these different variables to clarify these relationships . our results clearly clarified the potential of an appropriate regimen of regular pa among elders , particularly with the analysis of the changes in the detraining period . regarding the effects of detraining , like in previous studies , our results demonstrated that strength and flexibility gains after training decreased after 3 months of detraining , nevertheless the values remained significantly higher than before training . however , agility / dynamic balance in the at group reverted to lower values than the baseline . in opposition , we observed that aerobic endurance was the less affected component by detraining period . some studies indicate that the morphological and functional adaptations to training may disappear , even after short periods of detraining . therefore , like our data support , long - term exercise programs undertaken prior to activity cessation may offer functional protection . moreover , moderate to higher intensity training may maintain the gains for longer periods after training ends . on the other side , it is difficult to explain the discrepancy between the upper and lower body response to short - term detraining in this small sample . one possible explanation is that the initial training response was greater for lower - extremity strength than for upper - extremity strength and our subjects may have been less physically active than in some studies . moreover , when we analyzed the results of 1 - year followup , it was found that elders in the control group decreased their levels of all parameters of the fft , except for upper strength and flexibility , possibly because the muscles of the upper extremity are the most used and this could result in better physical function . this difference may also be explained by the activities performed in the leisure time , morphological differences in the connective and skeletal tissues , and hormonal differences . according to misic et al . muscle function is the most important predictor physical function of the lower extremities in the elderly . furthermore , aerobic endurance and fat mass are secondary predictors , which are widely associated with the functional capacity to perform various activities of daily living . these underlying results show that the negative effects of detraining reduce the functional capacity of the elderly and hence reflect on their hrqol , highlighting that pa should be practiced regularly . supporting these results , the literature shows that the elderly who became active had a better hrqol than their peers who remained sedentary wu et al . , which indicates the great value of exercise interventions in the elderly . strengths of this study include the objective measure of pa , through 15 months of study with a 1 - year intervention , controlled experimental design , and most importantly the opportunity to compare different intervention strategies . however , this study has some important limitations : first , there was no assessment of subjects ' dietary regimens throughout the investigation ; second , pa was not assessed during detraining and pa patterns could change during that time , due to seasonality ; third , there was an imbalance in group sizes . finally , probably the main limitation of this study is that participants were selected from long - term care institutions and they may not represent all older adults , in particular those who are physically independent and community - dwelling elders . further research is needed to determine whether diet and cardiovascular risk modification ameliorate cognitive and functional decline in elderly people . in conclusion , results highlight that a period of 3 months of detraining following 1 - year of health intervention programsagility / dynamic balance , lower body strength , and flexibility were the components of functional fitness most affected by detraining in the at . therefore , our data reinforce the idea that detraining affects physical fitness and elders should be engaged in a systematic exercise program throughout life in order to maintain or improve functional performance . thus , pa and ( or ) exercise prescriptions should emphasize components related to the maintenance of functional capacity and independence ; these will also improve cardiovascular health . since low pa levels are health risk factors for ageing subjects , health professionals need to be more effective promoting pa as an integral component of a healthy lifestyle . elders who undertake pa\noutput:\n" }, { "from": "agent", "value": "the purpose of this study is to assess the effects of different strategies of health on the levels of physical activity ( pa ) , physical fitness ( pf ) , cardiovascular disease ( cvd ) risk factors and quality of life ( qol ) of the institutionalized elderly . concurrently studies were made of the effect of detraining on these same variables . in this investigation we carried out a prospective longitudinal study with an experimental design , with 1 year plus 3 months of a detraining period . methodology . ( a ) a questionnaire with socio - demographic characteristics and a qol scale ( mos sf - 36 ) ; ( b ) functional fitness test to assess pf ; ( c ) an mti actigraph to evaluate the pa ; ( d ) biochemical analysis of blood , blood pressure and bio - impedance . the main results indicated that : ( i ) st significantly improved strength and body flexibility and at the aerobic endurance , agility / dynamic balance and lower strength and flexibility ; ( ii ) implications of detraining were more evident on the pa groups in the lower body flexibility , which is associated with agility / dynamic balance and lower strength in the at group ; ( iii ) cardiovascular variables improved significantly especially blood pressure , cholesterol and glucose in the st and hdl in the at group ; not having undergone significant changes with the detraining . the results of this thesis contribute positively to highlight the importance of pa in the promotion of health , prevention and reduction of cvd risk factors and the improvement of the pf and qol ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: this case uniquely highlights the successful non - operative management of isolated traumatic gallbladder perforation in a patient that was considered to be a high risk operative candidate . a 64 - year - old man with a background of alcoholic liver disease presented to our emergency department following high velocity blunt abdominal trauma . he had been driving at 60 miles / h when he lost control and car rolled - over . he was admitted under cardiology for further management of a fast narrow complex tachycardia , atrial fibrillation as this was the only outstanding issue . a transthoracic echocardiogram 2 days later revealed a right ventricular thrombus and he was therefore commenced on therapeutic low molecular weight heparin . on dayeight post - trauma , this gentleman was referred to general surgeons for abdominal distension and mild pain . he was stable hemodynamically and clinically he was found to have a soft , distended abdomen , with localized upper peritonism . a repeat ct scan reported free fluid and a perforated gallbladder [ figure 1 ] . computed tomography showing gallbladder fundus perforation ( red arrow ) and free intraperitoneal fluid ( blue arrow ) in view of his comorbidities , after multidisciplinary discussion conservative management was agreed . an endoscopic retrograde cholangio - pancreatogram ( ercp ) with stent insertion was performed and a radiologically - guided intra - peritoneal drain inserted . endoscopic retrograde cholangio - pancreatogram showing common bile duct ( green arrow ) , cystic duct ( blue arrow ) and extravasation of contrast from perforated gallbladder ( red arrow ) over the next few days , the patient 's condition improved . the intra - peritoneal drain was removed at day 12 post ercp and the patient was discharged , uneventfully 35 days after the injury . a follow - up ercp 2 month later revealed a normal cholangiogram with no obvious leak and no filling defects . gallbladder injury secondary to blunt abdominal trauma is very rare , approximating 2 % in the literature . the incidence of isolated gallbladder injury is even less as it tends to be protected anatomically by the liver , intestines , omentum , and rib cage . pre - disposing risk factors include recent alcohol consumption , a distended post - prandial gallbladder with a thin wall and malposition . traumatic gallbladder injuries usually present in three ways ; as an additional finding during the damage control surgery ( emergency laparotomy ) , with insidious onset of symptoms and signs a few days after the trauma and occasionally , a few weeks later with on - going non - specific abdominal complaints . laceration or perforation , which usually affect the gallbladder fundus , partial avulsions from the gallbladder fossa to near total traumatic cholecystectomy with or without disruption to the cystic duct and or cystic artery , and finally , contusions with an intramural hematoma contributing to wall necrosis and delayed perforation . losanoff and kjossev have formally previously categorized injuries to the gallbladder in an attempt to guide operative intervention and there is an evidence to suggest that this classification system has merit in dictating management . conservative measures such as cholecystostomy , percutaneous radiological intraperitoneal drainage or even cholecystorraphy have been reported , but found to be unsuccessful in the definitive control of gallbladder injury and invariably a cholecystectomy is required . others recommended an approach of diagnostic laparoscopy in equivocal trauma cases to identify gallbladder injury and once confirmed , proceed to laparoscopic cholecystectomy . furthermore , operative management is recommended in gallbladder injuries associated with additional varying degrees of extra - hepatic biliary ductal injuries ; either primary repair or duct to jejunum anastomosis with roux - en - y reconstruction . our patient was considered to be a high risk candidate for operation and we had to employ non - operative management , which was successful .\noutput:\n" }, { "from": "agent", "value": "isolated gallbladder perforations following blunt abdominal trauma are very rare . they often present with insidious onset of symptoms a few days after the initial insult and an operative course of management ensues . this is in the form of a cholecystectomy and peritoneal lavage ; more often via laparotomy rather than laparoscopically . conservative management , in the form of cholecystostomy , percutaneous intraperitoneal drainage or cholecystorraphy has been described ; however , these cases have invariably resulted in cholecystectomy eventually . the case uniquely highlights the successful non - operative management of isolated traumatic gallbladder perforation ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we developed a conceptual framework to help position models of tb diagnostic testing . in this framework ( figure ) , models generally consider diagnostics at a point along the timeline from development ( future tests ) , to deployment ( recently released tests ) , to optimization ( existing tests ) . this timeline is an iterative one ; for example , optimization can inform future deployment efforts , and both can inform development of the next generation of novel tests . the outcomes of these modelling analyses may include different combinations of epidemiology ( population level impact ) , implementation ( patient and health system impact ) , and economics ( resource requirements and cost - effectiveness ) . thus , for example , a model of hypothetical cost - effectiveness of diagnostics12 may position itself to the far lower left of this grid , whereas an xpert scale - up model within populations and health systems11 may position itself to the mid - upper right . a conceptual framework for models of current and future tb diagnostic tests . models can be positioned along a spectrum of development - deployment - optimization on one axis and an interface between outcomes related to epidemiology , health systems and economics on the other . models can address more than one box at a time ; representative modelling questions are provided , although others might reasonably be posed . after constructing the conceptual framework above , we developed a list of priorities in each of the four streams for which models could improve decision making and ultimately population health ( table 2 ) . modelling priorities : diagnostic tests for active tb given the rapid global scale - up of xpert ,13 there is considerable pressure for country - level policy makers to decide if and how to introduce and / or scale up xpert within existing programs . high - quality evidence exists as to the accuracy of xpert ,5 but to quantitatively project the population - level impact and cost - effectiveness of different xpert scale - up strategies , estimates of numerous other parameters ( e.g. , rates of tb transmission , diagnosis and mortality ) must be incorporated into a unified modelling framework .14 models that provide evidence - based estimates of cost and / or avertible morbidity and mortality under different implementation policies would provide valuable platforms to guide rational decision making ( figure , column 2 , rows 13 ) . in most cases , however , policy decisions related to xpert implementation are made without the benefit of such model - based guidance . a small number of existing models have indicated that xpert scale - up is likely to be cost - effective ( using conventional thresholds of willingness to pay ) in a limited number of settings .1418 however , these models may not be generalizeable , and in areas with severe resource constraints , anti - tuberculosis treatment may be relatively cheap , whereas xpert may be less affordable , thereby generating high opportunity costs for xpert - based diagnosis .19 furthermore , scale - up of xpert may entail massive downstream costs , including treatment for multidrug - resistant tb20 and long - term human immunodeficiency virus ( hiv ) therapy for people cured of tb .21 models must also consider the additional costs of embedding xpert effectively within health systems ( e.g. , power and climate control , staff retraining and backup systems when equipment fails ) . against this background , we present a list of high - priority questions that should be addressed in model - based analyses of xpert scale - up , including questions related to epidemiology , health systems and economic impact ( table 2 ) . a key consideration is the outstanding need for setting - specific models that are calibrated to existing epidemiological data ( e.g. , tb incidence , hiv prevalence and multidrug - resistant tb [ mdr - tb ] prevalence ) and structured to consider practical details related to health system access and diagnostic pathways for tb . these features are important in guiding the best approach for xpert scale - up within existing programs ( questions 1 and 2 ) , determining how modifications of existing pathways to diagnosis and care can be modified to maximize the benefits of xpert ( question 3 ) and understanding how xpert scale - up might affect broad resource needs ( e.g. , mdr - tb or hiv treatment capacity ) ( question 4 ) . in summary , new models addressing these priority needs would facilitate country - level decision making by providing quantitative , evidence - based comparisons of alternative strategies for xpert scale - up . critical to the success of these models is early and ongoing engagement with local organizations ( e.g. , national tuberculosis programs ) that are tasked with actual scale - up decisions . there is currently great industry interest in tb diagnostics , with more than 50 companies actively developing tb diagnostic technologies .22 this interest reflects many unmet needs . not only is xpert too expensive and infrastructure - dependent to be widely deployed in decentralized settings ,23 we also lack good tests for latent tuberculous infection , and extra - pulmonary and childhood tb . given these pressing needs , it is essential to guide test developers as to which assays will have the greatest impact on tb epidemiology , health systems / clinical care and economic considerations ( i.e. , figure , column 1 , rows 13 ) . by comparing assays with different niches and different specifications according to these three classes of outcomes , models can help test developers focus on those products likely to have not only the largest market but also the most potential to reduce disease burden . one mechanism for providing such guidance is through the development of tpps , which are widely used in the pharmaceutical industry to focus drug development on key attributes .24,25 tpps are being developed for a wide array of tb diagnostic tests , and well - designed models can guide developers as to which new tb tests need to be prioritized for development and , within those tpps , those attributes that are of critical importance .26 of particular importance is a working definition of point - of - care ( poc ) testing .2 whereas most current definitions of a poc test are product - oriented ( e.g. , a simple , low - cost dipstick deployable in the community ) , we argue that the most critical goal of a poc testing process is to ensure rapid treatment , as treatment is required to improve patient health and reduce transmission . thus , we propose a new definition of poc testing for tb , i.e. , testing that will result in a clear , actionable management decision within the same clinical encounter . this goal - oriented definition suggests that tpps should explicitly describe a test 's clinical purpose ( e.g. , triage , diagnosis of pulmonary tb , dst ) ; therapeutic goal ( e.g. , same - day treatment initiation ) ; target population ( e.g. , children , community - dwelling adults , hiv clinic ) ; level of implementation ( home , community , clinic , peripheral laboratory , hospital ) ; and likely users . in response to this need , we identified a list of 10 potential tpps that well - designed comparative models could prioritize ( table 2 ) . once priority tpps are selected , more focused models can prioritize further among the various attributes included in the tpp , such as accuracy , turnaround time , price , patient acceptability ( e.g. , blood and urine more often preferred over sputum ) and the ability to be deployed within existing health systems as part of a poc testing program . ultimately , tpp development and modelling represent an iterative process , with models helping to refine and compare each successive tpp as knowledge and prototypes emerge . with several new tb drugs in the pipeline , the prospect of a first - line treatment regimen against which no resistance exists may eventually become a reality .24 more immediately , shortened first - line regimens based on combinations of current and repurposed tb drugs are emerging .4 fluoroquino - lone - based regimens are of particular interest , and a clinical trial was recently initiated based on the early bactericidal activity of a regimen in which the novel nitroimidazooxazine pa - 824 is combined with moxifloxacin and pyrazinamide ( pamz ) .27 as many novel regimens rely heavily on fluoroquinolones and pyrazinamide ( pza ) , they may need to be restricted to patients with organisms susceptible to these drugs ; unlike for rifampin ( rmp ) , stand - alone dst for these two drugs currently does not exist . dst against pza is particularly difficult , as phenotypic testing requires acidic conditions , and genotypic testing must account for over 200 mutations ( mostly in a single gene , pnca ) potentially associated with resistance .28 it is therefore important to specify the dst assays most urgently needed for development ( e.g. , combined assay for rmp , fluoroquinolones and pza resistance vs. stand - alone tests for each drug ) and the most important assay attributes , including accuracy , infrastructure and biosafety requirements , and price . in other words , we need a tpp for next - generation dst . in addition to assay development , it is also critical to understand how these assays should best be deployed . for example , must all individuals receiving a novel first - line regimen be tested for full susceptibility or can we restrict testing to people at high risk for drug resistance ( e.g. , rmp - resistant on xpert , previously treated for tb ) and / or death ( e.g. , hiv ) ? these questions of optimal dst assay development and deployment can be answered by assessing the impact of each alternative on epidemiology , health systems and economics ( figure , column 1 , rows 13 ) . models provide a quantitative , structured mechanism for making such comparisons . we propose that these questions be addressed over both short - term horizons ( informing urgent policy decisions ) and longer - term ones ( informing sustainable approaches ) , acknowledging that epidemics of drug - resistant tb are often slow to emerge .29 we define a series of clinically oriented scenarios and assay - oriented algorithms that should be considered by models ( table 2 ) . for shorter horizons ( e.g. , 5 years ) , decision analytic models could assess the implementation and cost - effectiveness ( i.e. , health systems and economic impact ) of these scenario - algorithm combinations for both rmp - containing , fluoroquinolone - based regimens and realistic rmp - free regimens ( e.g. , pamz ) . for longer horizons ( e.g. , 2050 years ) , dynamic models incorporating assumptions about tb transmission could compare the epidemiological impact on the emergence of drug - resistant tb , considering also regimens of entirely novel compounds . ultimately , as with xpert scale - up , these questions must be answered in a variety of epidemiological and economic settings , and in close communication with the relevant stakeholders . as demonstrated by our systematic review ( tb mac 2 : review of tb diagnostic modelling , available at www.tb-mac.org/resources ) , current models of tb diagnostics have a limited literature base on which to draw . existing transmission models of tb diagnosis suffer from fundamental parameter and structural uncertainties , including questions regarding the amount of transmission that occurs before patients seek diagnosis , the trajectory of infectiousness over time and effects of contact structure on the timing of transmission .30 data are also scarce as to how patients access diagnostic testing within existing health systems ( e.g. , public vs. private sector diagnosis ) and how diagnostic test results subsequently affect outcomes ( e.g. , if patients are lost to care before receiving test results ) . from the economic perspective , there is also a dearth of geographically representative data on the costs of key tb diagnostic assays and the costs incurred by patients specifically during the diagnostic process , despite recent systematic reviews3133 of the overall costs to patients of health care seeking for tb . these questions are particularly relevant to deploying emerging tests and optimizing existing diagnostic algorithms ( figure , columns 23 ) . we identified a set of critical analytical and modelling needs required to improve existing models of tb diagnostics ( table 2 ) . first , we need to more clearly understand when tb transmission occurs relative to the timing of diagnosis , treatment initiation , and losses to follow - up . for example , how much transmission occurs between a missed diagnosis and subsequent diagnosis leading to treatment initiation ? we disaggregate these considerations into biological and behavioral components ; specifically , we lack data on how symptoms and infectiousness evolve over an individual 's disease course , and on how contact patterns and care - seeking behavior differ over time and space . studies to fill these gaps could include intensified evaluations of contact networks and outbreaks linking records of patient behavior with advanced molecular epidemiology ( e.g. , whole - genome sequencing ) to better pinpoint the timing of transmission and disease .34 second , we need a better understanding of how tb patients interact with the health system during the diagnostic process , including the number , type and timing of interactions ( and losses to follow - up ) within that system over their disease course ( figure , row 2 ) . detailed data on health service utilization might be better collected during pragmatic clinical trials of tb diagnostics ,35 including more detail on the pathways of those patients lost to care . third , to better inform economic evaluations ( figure , row 3 ) , we need better data on health systems resource requirements and patient costs associated with tb diagnosis . to meet this need , we can not conduct costing studies in each country , but well - selected , comprehensive costing studies in different regions and income levels , coupled with econometric models to extrapolate data to other settings , could be invaluable . two priority model - development needs identified were improved health systems models to better assess the operational placement of new tb diagnostics , and user - friendly models for decision making at the country level . given the rapid global scale - up of xpert ,13 there is considerable pressure for country - level policy makers to decide if and how to introduce and / or scale up xpert within existing programs . high - quality evidence exists as to the accuracy of xpert ,5 but to quantitatively project the population - level impact and cost - effectiveness of different xpert scale - up strategies , estimates of numerous other parameters ( e.g. , rates of tb transmission , diagnosis and mortality ) must be incorporated into a unified modelling framework .14 models that provide evidence - based estimates of cost and / or avertible morbidity and mortality under different implementation policies would provide valuable platforms to guide rational decision making ( figure , column 2 , rows 13 ) . in most cases , however , policy decisions related to xpert implementation are made without the benefit of such model - based guidance . a small number of existing models have indicated that xpert scale - up is likely to be cost - effective ( using conventional thresholds of willingness to pay ) in a limited number of settings .1418 however , these models may not be generalizeable , and in areas with severe resource constraints , anti - tuberculosis treatment may be relatively cheap , whereas xpert may be less affordable , thereby generating high opportunity costs for xpert - based diagnosis .19 furthermore , scale - up of xpert may entail massive downstream costs , including treatment for multidrug - resistant tb20 and long - term human immunodeficiency virus ( hiv ) therapy for people cured of tb .21 models must also consider the additional costs of embedding xpert effectively within health systems ( e.g. , power and climate control , staff retraining and backup systems when equipment fails ) . against this background , we present a list of high - priority questions that should be addressed in model - based analyses of xpert scale - up , including questions related to epidemiology , health systems and economic impact ( table 2 ) . a key consideration is the outstanding need for setting - specific models that are calibrated to existing epidemiological data ( e.g. , tb incidence , hiv prevalence and multidrug - resistant tb [ mdr - tb ] prevalence ) and structured to consider practical details related to health system access and diagnostic pathways for tb . these features are important in guiding the best approach for xpert scale - up within existing programs ( questions 1 and 2 ) , determining how modifications of existing pathways to diagnosis and care can be modified to maximize the benefits of xpert ( question 3 ) and understanding how xpert scale - up might affect broad resource needs ( e.g. , mdr - tb or hiv treatment capacity ) ( question 4 ) . in summary , new models addressing these priority needs would facilitate country - level decision making by providing quantitative , evidence - based comparisons of alternative strategies for xpert scale - up . critical to the success of these models is early and ongoing engagement with local organizations ( e.g. , national tuberculosis programs ) that are tasked with actual scale - up decisions . there is currently great industry interest in tb diagnostics , with more than 50 companies actively developing tb diagnostic technologies .22 this interest reflects many unmet needs . not only is xpert too expensive and infrastructure - dependent to be widely deployed in decentralized settings ,23 we also lack good tests for latent tuberculous infection , and extra - pulmonary and childhood tb . given these pressing needs , it is essential to guide test developers as to which assays will have the greatest impact on tb epidemiology , health systems / clinical care and economic considerations ( i.e. , figure , column 1 , rows 13 ) . by comparing assays with different niches and different specifications according to these three classes of outcomes , models can help test developers focus on those products likely to have not only the largest market but also the most potential to reduce disease burden . one mechanism for providing such guidance is through the development of tpps , which are widely used in the pharmaceutical industry to focus drug development on key attributes .24,25 tpps are being developed for a wide array of tb diagnostic tests , and well - designed models can guide developers as to which new tb tests need to be prioritized for development and , within those tpps , those attributes that are of critical importance .26 of particular importance is a working definition of point - of - care ( poc ) testing .2 whereas most current definitions of a poc test are product - oriented ( e.g. , a simple , low - cost dipstick deployable in the community ) , we argue that the most critical goal of a poc testing process is to ensure rapid treatment , as treatment is required to improve patient health and reduce transmission . thus , we propose a new definition of poc testing for tb , i.e. , testing that will result in a clear , actionable management decision within the same clinical encounter . this goal - oriented definition suggests that tpps should explicitly describe a test 's clinical purpose ( e.g. , triage , diagnosis of pulmonary tb , dst ) ; therapeutic goal ( e.g. , same - day treatment initiation ) ; target population ( e.g. , children , community - dwelling adults , hiv clinic ) ; level of implementation ( home , community , clinic , peripheral laboratory , hospital ) ; and likely users . in response to this need , we identified a list of 10 potential tpps that well - designed comparative models could prioritize ( table 2 ) . once priority tpps are selected , more focused models can prioritize further among the various attributes included in the tpp , such as accuracy , turnaround time , price , patient acceptability ( e.g. , blood and urine more often preferred over sputum ) and the ability to be deployed within existing health systems as part of a poc testing program . ultimately , tpp development and modelling represent an iterative process , with models helping to refine and compare each successive tpp as knowledge and prototypes emerge . with several new tb drugs in the pipeline , the prospect of a first - line treatment regimen against which no resistance exists may eventually become a reality .24 more immediately , shortened first - line regimens based on combinations of current and repurposed tb drugs are emerging .4 fluoroquino - lone - based regimens are of particular interest , and a clinical trial was recently initiated based on the early bactericidal activity of a regimen in which the novel nitroimidazooxazine pa - 824 is combined with moxifloxacin and pyrazinamide ( pamz ) .27 as many novel regimens rely heavily on fluoroquinolones and pyrazinamide ( pza ) , they may need to be restricted to patients with organisms susceptible to these drugs ; unlike for rifampin ( rmp ) , stand - alone dst for these two drugs currently does not exist . dst against pza is particularly difficult , as phenotypic testing requires acidic conditions , and genotypic testing must account for over 200 mutations ( mostly in a single gene , pnca ) potentially associated with resistance .28 it is therefore important to specify the dst assays most urgently needed for development ( e.g. , combined assay for rmp , fluoroquinolones and pza resistance vs. stand - alone tests for each drug ) and the most important assay attributes , including accuracy , infrastructure and biosafety requirements , and price . in other words , we need a tpp for next - generation dst . in addition to assay development , it is also critical to understand how these assays should best be deployed . for example , must all individuals receiving a novel first - line regimen be tested for full susceptibility or can we restrict testing to people at high risk for drug resistance ( e.g. , rmp - resistant on xpert , previously treated for tb ) and / or death ( e.g. , hiv ) ? these questions of optimal dst assay development and deployment can be answered by assessing the impact of each alternative on epidemiology , health systems and economics ( figure , column 1 , rows 13 ) . we propose that these questions be addressed over both short - term horizons ( informing urgent policy decisions ) and longer - term ones ( informing sustainable approaches ) , acknowledging that epidemics of drug - resistant tb are often slow to emerge .29 we define a series of clinically oriented scenarios and assay - oriented algorithms that should be considered by models ( table 2 ) . for shorter horizons ( e.g. , 5 years ) , decision analytic models could assess the implementation and cost - effectiveness ( i.e. , health systems and economic impact ) of these scenario - algorithm combinations for both rmp - containing , fluoroquinolone - based regimens and realistic rmp - free regimens ( e.g. , pamz ) . for longer horizons ( e.g. , 2050 years ) , dynamic models incorporating assumptions about tb transmission could compare the epidemiological impact on the emergence of drug - resistant tb , considering also regimens of entirely novel compounds . ultimately , as with xpert scale - up , these questions must be answered in a variety of epidemiological and economic settings , and in close communication with the relevant stakeholders . as demonstrated by our systematic review ( tb mac 2 : review of tb diagnostic modelling , available at www.tb-mac.org/resources ) , current models of tb diagnostics have a limited literature base on which to draw . existing transmission models of tb diagnosis suffer from fundamental parameter and structural uncertainties , including questions regarding the amount of transmission that occurs before patients seek diagnosis , the trajectory of infectiousness over time and effects of contact structure on the timing of transmission .30 data are also scarce as to how patients access diagnostic testing within existing health systems ( e.g. , public vs. private sector diagnosis ) and how diagnostic test results subsequently affect outcomes ( e.g. , if patients are lost to care before receiving test results ) . from the economic perspective , there is also a dearth of geographically representative data on the costs of key tb diagnostic assays and the costs incurred by patients specifically during the diagnostic process , despite recent systematic reviews3133 of the overall costs to patients of health care seeking for tb . these questions are particularly relevant to deploying emerging tests and optimizing existing diagnostic algorithms ( figure , columns 23 ) . we identified a set of critical analytical and modelling needs required to improve existing models of tb diagnostics ( table 2 ) . first , we need to more clearly understand when tb transmission occurs relative to the timing of diagnosis , treatment initiation , and losses to follow - up . for example , how much transmission occurs between a missed diagnosis and subsequent diagnosis leading to treatment initiation ? how much transmission can be averted through active tb screening ? we disaggregate these considerations into biological and behavioral components ; specifically , we lack data on how symptoms and infectiousness evolve over an individual 's disease course , and on how contact patterns and care - seeking behavior differ over time and space . studies to fill these gaps could include intensified evaluations of contact networks and outbreaks linking records of patient behavior with advanced molecular epidemiology ( e.g. , whole - genome sequencing ) to better pinpoint the timing of transmission and disease .34 second , we need a better understanding of how tb patients interact with the health system during the diagnostic process , including the number , type and timing of interactions ( and losses to follow - up ) within that system over their disease course ( figure , row 2 ) . detailed data on health service utilization might be better collected during pragmatic clinical trials of tb diagnostics ,35 including more detail on the pathways of those patients lost to care . third , to better inform economic evaluations ( figure , row 3 ) , we need better data on health systems resource requirements and patient costs associated with tb diagnosis . to meet this need , we can not conduct costing studies in each country , but well - selected , comprehensive costing studies in different regions and income levels , coupled with econometric models to extrapolate data to other settings , could be invaluable . two priority model - development needs identified were improved health systems models to better assess the operational placement of new tb diagnostics , and user - friendly models for decision making at the country level . in the rapidly shifting landscape of tb diagnosis , stakeholders including industry leaders , policy makers and implementers need data - driven guidance about which assays to develop , how to deploy emerging assays within existing health systems , and how to optimize existing assays and algorithms in the field . these decisions must maximize the impact of diagnostics on epidemiology , health systems and clinical management using tightly constrained resources . the urgency of the decision - making process greatly outpaces our present ability to collect definitive data on these outcomes . as suchwe present a conceptual framework for models of tb diagnostics ( figure ) and define modelling priorities in four streams ( table 2 ) . in an environment characterized by urgent questions and severe resource constraints , this framework may help guide data gathering and modelling efforts , with the ultimate goal of enabling decision makers to develop , deploy and optimize tb diagnostics in a way that maximizes impact and effectively translates resources into better health .\noutput:\n" }, { "from": "agent", "value": "summarythe landscape of diagnostic testing for tuberculosis ( tb ) is changing rapidly , and stakeholders need urgent guidance on how to develop , deploy and optimize tb diagnostics in a way that maximizes impact and makes best use of available resources . when decisions must be made with only incomplete or preliminary data available , modelling is a useful tool for providing such guidance . following a meeting of modelers and other key stakeholders organized by the tb modelling and analysis consortium , we propose a conceptual framework for positioning models of tb diagnostics . we use that framework to describe modelling priorities in four key areas : xpert mtb / rif scale - up , target product profiles for novel assays , drug susceptibility testing to support new drug regimens , and the improvement of future tb diagnostic models . if we are to maximize the impact and cost - effectiveness of tb diagnostics , these modelling priorities should figure prominently as targets for future research ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: gastric neuroendocrine tumors ( nets ) , previously referred to as gastric carcinoids , are rare neoplasms that account for 0.6 % to 2 % of all identified gastric polyps and 8.7 % of all gastrointestinal nets .12 the incidence of gastric nets has increased over the last 50 years , partly due to the improvement of endoscopic surveillance and heightened awareness .13 gastric nets are usually classified into three types based on the background gastric pathology . type 1 arises in the presence of achlorhydric atrophic body gastritis ( abg ) , type 2 is associated with the zollinger - ellison syndrome ( zes ) and multiple endocrine neoplasia type 1 ( men - 1 ) , while type 3 includes the \" sporadic \" net in the absence of a specific background of pathologic changes .4 this classification plays an important clinical role when approaching a gastric net , not only due to the possible coexistence of a predisposing condition such as abg and zes , but also due to the implications in tumor behavior and the prognosis of the patient . type 3 gastric net represents 14 % to 25 % of gastric nets and have poor prognosis with the highest rate of distant metastasis .56 they mostly are large ( 2 cm ) solitary lesions arising in the normal surrounding mucosa .7 in this case , we describe a patient with multicentric ( more than 10 ) small gastric nets identified as type 3 . a 50 - year - old woman underwent an esophagogastroduodenoscopy ( egd ) for a health check - up . more than 10 polypoid lesions of the stomach were discovered , and the biopsy specimens from the gastric polyps demonstrated grade 1 ( g1 ) net , according to world health organization classification .8 she was referred to our hospital for proper management of the gastric nets . she had no carcinoid symptoms such as flushes or diarrhea , had no significant medical history , and did not previously receive any proton pump inhibitors or h2 receptor antagonists . the results of the peripheral blood and routine chemistry tests were within the normal limits . the serum level of fasting gastrin was 85.2 pg / ml ( normal rage , 0 to 90 ) . the serum level of pepsinogen i ( pg i ) was 70.7 ng / ml and that of pepsinogen ii ( pg ii ) was 10.9 ng / ml with the pg i / ii ratio being 6.48 ( positive range , pg i 70 ng / ml and pg i / ii 3.0 ratio ) . pylori immunoglobulin g antibody level was 9.1 au / ml with equivocal range ( negative range , 8.0 au / ml ) . on egd ( a5 ce0 mode , gif - q260 scope ; olympus optical , tokyo , japan ) , multiple polypoid lesions were detected mainly around the greater curvature of the gastric body to the fundus . some polyps accompanied the erythematous mucosal change , and the maximum diameter of polyps was less than 15 mm ( fig . focal granular mucosal change was detected in the gastric body , but there was no evidence of atrophic gastritis in the antrum ( fig .1 c ) . a computed tomography scan of the abdomen and pelvis revealed multiple enhancing polypoid lesions in the stomach without any evidence of metastatic lesions . polypectomy was performed without complications and almost all the gastric polyps that were greater than 5 mm in size were removed . a histological examination revealed that all the removed polys were net gi , which was composed of uniform cells with round or ovoid nuclei and scanty eosinophilic cytoplasm , proliferating in a trabecular or glandular pattern ( fig . the tumor cells invaded the submucosal layer , diffusely staining for chromogranin a. the mitotic count was absent and the ki - 67 index was less than 1 % . most significantly , three of the polyps extended to the lateral or vertical resection margins and two exhibited lymphovascular invasion . fundic gland atrophy was not detected from random biopsies on the greater curvature of the upper body , mid - body , and antrum . after the procedure , she still refused surgery despite the high risk of metastasis and tumor - related death . follow - up egd at 6 months after diagnosis showed multiple remnant gastric polyps suggestive of gastric nets ( fig . gastric nets were first categorized into three types in 1993 by rindi et al. 4 type 1 and 2 are related to the presence of hypergastrinemia causing hyperplasia of the precursor enterochromaffin - like ( ecl ) cells , whereas type 3 occurs sporadically and independently of gastrin .4 this classification is based on the clinical differences of epidemiological , pathophysiological , endoscopic , and histological features between each type that affects prognosis , management , and follow - up .9 type 1 and 2 gastric net have indolent behaviors , but type 3 gastric net may be life - threatening with a high risk of metastasis and tumor - related death .7 in type 1 and 2 gastric net , hypergastrinemia plays a crucial role in the development of tumors .10 the ecl cells , located in the corpus - fundus mucosa of the stomach , represent the major proliferative target of gastrin . gastric net arising from these conditions grows usually multicentric lesions . on the other hand , types 3 gastric nets are \" gastrin - independent \" tumors that are rarely multiple .4 endoscopically , type 1 gastric net tumors are often found in the fundus of stomach and are mostly polypoid ( 78 % ) , of small shape ( size 5 to 8 mm ) , and are multicentric ( 68 % ; mean number , 3 ) .1112 type 2 gastric nets are also usually identified as small , often multiple , polypoid tumors ( 1 cm in size ) in fundus .13 on the contrary , a type 3 gastric net is typically a large ( 1 cm , 66 % ) , solitary ( 96 % ) lesion , that grows from the gastric body / fundus , and occurs in the antrum , within the context of a normal gastric mucosa .1415 in this case , the endoscopic findings of multicentric ( 10 lesions ) , small ( 2 cm ) polypoid lesions in the gastric fundus resembled closely to the type 1 and 2 gastric nets . however , the diagnosis of type 3 gastric net was clinically based on normal gastrin levels and the absence of evidence of gastric atrophy or significant peptic ulcers that are commonly seen with type 1 or 2 gastric nets , respectively . some cases of multiple gastric nets in men 1 patients without hypergastrinemia have been previously described .161718 these cases suggest that the development of gastric net in men 1 patients arises not only from hypergastrinemia in zes , but also from the genetic mutations of the men 1 gene , one of the tumor suppressor genes . moriyama et al. 19 first reported multicentric gastric nets that have been classified as type 3 . in this case , the patient concomitantly had a pituitary tumor , an adenomatous goiter , and bilateral warthin 's tumors . although a possible predisposition to men 1 is suspected , genetic mutations could not be found in all the exons of the men 1 gene that has been translated . to our knowledge , this is the second report of a multicentric type 3 gastric net . type 3 gastric nets exhibit a more aggressive course than the type 1 and 2 gastric nets . most type 3 gastric nets showed lymphovascular and deep wall invasion at the time of diagnosis .20 in other cases , 60 % to 75 % present with metastatic disease , and tumor - related death occurs 28 months after diagnosis in 25 % to 30 % of cases .420 thus , the therapeutic approach to type 3 gastric nets should be managed surgically .9 only small ( 10 mm ) , well differentiated ( g1 ) type 3 gastric nets limited to the submucosal layer have been treated efficaciously by endoscopic mucosectomy , in a retrospective analysis .15 in summary , we described the case of a 50 - year - old woman with multicentric type 3 gastric net without hypergastrinemia , which was endoscopically similar to the type 1 and 2 lesions but with more aggressive features , such as lymphovascular invasion . it will be necessary to study various other cases in order to discover the pathogenesis , and develop therapeutic strategies . this case serves as a reminder to gastroenterologists who encounter net cases in their clinical practice , that even if the net is multiple , a diagnosis of type 3 net should be considered so that a careful evaluation of atrophic status such as endoscopic findings , serologic biomarkers , and gastrin levels can be conducted .\noutput:\n" }, { "from": "agent", "value": "a 50 - year - old woman with incidentally detected multiple gastric polyps and biopsy - proven neuroendocrine tumor ( net ) was referred to our hospital . more than 10 polypoid lesions ( less than 15 mm ) with normal gastric mucosa were detected from the gastric body to the fundus . the serum level of gastrin was within the normal limits . there was no evidence of atrophic changes on endoscopy and serologic marker as pepsinogen i / ii ratio . computed tomography of the abdomen and pelvis revealed no evidence of metastatic lesions . she refused surgery , and we performed endoscopic polypectomy for almost all the gastric polyps that were greater than 5 mm . although the histological examination revealed that all the removed polys were diagnosed as net g1 , three of them extended to the lateral or vertical resection margins , while two exhibited lymphovascular invasion . a follow - up upper endoscopy that was performed 6 months after the diagnosis showed multiple remnant gastric polyps that were suggestive of remnant gastric net ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the prevalence and severity of pain among cancer patients has notably increased in recent years .13 experts in pain management have estimated that a significant number of all cancer patients die without adequate pain relief , despite the fact that the tools for adequate pain control are available .2 several factors considered to be barriers to cancer pain management have already been reported ,4 and the physician s knowledge of cancer pain management has been rated highly among those factors .1,4 with the appropriate anticancer therapies , opioids drugs , nerve blocks , and other techniques , such as psychosocial care , satisfactory pain relief could be achieved for most cancer patients . although the world health organization ( who ) analgesic ladder is effective for more than 80 % of cancer pain , the addition of appropriate adjuvant drugs , along with early intervention , is needed for an improved and prolonged quality of life ( qol ) . effective cancer pain treatment requires a holistic approach , with timely assessments , measurements of pain , an understanding of the pathophysiology involved in causing particular types of pain , and an understanding of drugs to relieve particular types of pain . the aim of this report is to evaluate the knowledge of cancer pain management among medical practitioners in our center . ahmadu bello university teaching hospital is a tertiary teaching hospital located in the north - western part of nigeria . this hospital is a referral center and plays a major role in health care delivery in this part of the country . we carried out a study that sought to evaluate the knowledge of cancer pain management among medical practitioners , using a structured questionnaire to obtain the necessary information ( figure s1 ) . the questionnaire was drafted by one of the authors ( jgm ) , critically reviewed by the co - authors ( lmdy and eon ) , pre - tested , and validated using a population similar to the target population . it was evident that a subset of the target population and a similar independent population both clearly understood the questionnaire s information . the questionnaire was administered , face to face , to all the doctors directly involved in the management of cancer patients at the ahmadu bello university teaching hospital . the medical practitioners read the questionnaire and ticked the appropriate boxes ( or wrote their responses where applicable ) . the population of medical practitioners was composed of house officers , medical officers , registrars , senior registrars , and consultants . newly employed medical practitioners , those who had not spent a minimum of 3 months in the hospital , and / or those that were not directly involved in the management of cancer patients were excluded from the study . the questionnaire utilized both open - and closed - ended questions to determine whether respondents considered pain to be a significant health problem among cancer patients . the questionnaire was also designed to determine how frequently the physician attended to cancer patients and whether he or she made a routine assessment of pain in these patients . the most appropriate modality of cancer pain control and the commonly used form of analgesic for cancer patients was also determined . respondents were also asked whether they would consider changing the strength of the analgesic used for a patient or leave the patient alone if the first attempt at abating the pain failed . limitations to cancer pain management were also determined and whether the respondents have had formal training on pain management . statistical data analysis was carried out using spss ( version 11.5 , ibm corporation , armonk , n y , usa ) . simple frequencies were determined for variables . where multiple responses were required , each response was treated as a separate variable . eighty - two ( 82 ) medical practitioners responded to the questionnaire , aged 23 to 50 years ( mean , 34.9 ) . thirty - six ( 43.9 % ) strongly agreed that cancer patients require pain relief ; while 27 ( 32.9 % ) agreed , ten ( 12.2 % ) were undecided , six ( 7.3 % ) disagreed , and three ( 3.7 % ) strongly disagreed ( figure 2 ) . thirty - six ( 43.9 % ) attended to cancer patients every day , 21 ( 25.6 % ) attended to cancer patients twice weekly , 18 ( 22.0 % ) attended weekly , and seven ( 8.5 % ) attended monthly ( figure 3 ) . forty - nine ( 59.8 % ) did not routinely make pain assessments among cancer patients , while 33 ( 40.2 % ) did ( figure 4 ) . concerning the most commonly used treatment protocol for pain relief in cancer patients , the survey results revealed that 42 ( 51.2 % ) of the respondents treated for pain only when patients complained ( table 1 ) . the types of analgesics commonly used for cancer patients were weak opioids , 38 ( 43.3 % ) ; non - steroidal anti - inflammatory drugs ( nsaids ) , 26 ( 31.7 % ) ; and strong opioids , 16 ( 19.5 % ) ; while two ( 2.4 % ) of the respondents used other modalities ( figure 5 ) . concerning the action to be taken if the first attempt at treating cancer pain failed , 36 ( 43.9 % ) of the respondents would give stronger analgesics , 29 ( 35.4 % ) would combine stronger and mild analgesic , 14 ( 17.1 % ) would reassure the patient , and three ( 3.7 % ) would use a non - drug modality ( figure 6 ) . in the case of perceived limitations to adequate cancer pain management , 44 ( 53.7 % ) of the respondents felt that they had poor knowledge of cancer pain management , 18 ( 22 . % ) were of the opinion that patients arrive at the hospital with already advanced stages of cancer , 13 ( 15.9 % ) were afraid of serious drug side effects , while seven ( 8.5 % ) reported the non - availability of stronger analgesic drugs ( figure 7 ) . when respondents were asked whether they have had any formal training on pain management , 75 ( 91.5 % ) had no formal training , while only seven ( 8.5 % ) had received some formal training on pain management . in the past years , tremendous progress has been made in the understanding of the mechanisms of cancer pain .14 cancer pain , affecting 50 % of patients at any given cancer stage and 75 % of patients with advanced cancers ,5 has been studied and defined in relation to the following : causes neoplastic disease , 60 % 80 % ; therapies , 25 % 20 % ; not associated with either disease or therapy , 10 % 5 % ; pathophysiological characteristics ( nociceptive pain , 50 % 70 % ; neuropathic pain , 10 % 30 % ; mixed pain , 20 % 40 % ) ; intensity ( severe pain in 30 % of cases ) ; and the number of pain sites ( one pain site , 20 % ; 24 pain sites , 60 % ; and .4 pain sites , 20 % ) .68 the pathogenesis of malignancy - associated pain is often heterogeneous , and a significant percentage of cancer patients have pain that is produced by multiple mechanisms . thus , an understanding of the pathophysiology of cancer pain may have therapeutic implications and may influence the selection of pharmacological and non - pharmacological treatments . the who three - step analgesic ladder has been the gold standard for the therapy of cancer pain .2 however , a treatment approach that determines the sequence of analgesic therapies , based primarily on an individualized therapeutic course for cancer pain , will inevitably replace the epidemiologically based approach of the who three - step ladder s measure of pain intensity . replacing the who three - step ladder with a multifaceted approach is linked to the most progressive scientific thinking . as an understanding of the specific cellular mechanisms of cancer pain increases , more effective therapies can be developed , targeting the precise mediators of pain according to both the nature of a specific tumor and the individual suffering from pain .10 several of the specific mediators of cancer pain have been identified .10,11 it has been discovered that certain tumors release cancer pain mediators , such as cyclo - oxygenase - 2 ( cox - 2 ) , peptide endothelin - 1 , and malignancy - associated acidosis , which sensitize or stimulate primary afferent neurons .10,11 it is essential to perform a comprehensive evaluation of pain in cancer patients .12,13 the severity of cancer pain is dynamic , often fluctuating as the disease progresses and as different therapies are administered .14 therefore , it is necessary to evaluate and re - evaluate the patient s pain in order to determine the severity on a serial basis .1517 this therefore becomes a necessity , that routine assessment of pain in cancer patients should be done . in our report , only 40 % of the medical practitioners in ahmadu bello university teaching hospital admitted to performing routine assessments of pain among their cancer patients ( figure 4 ) . a survey by soyannwo et al among surgeons in west africa reported that pain assessment was mostly by the verbal rating scale , and only 20 % included psychological measurements in their schedules .18 our survey results revealed that 51.2 % of the respondents treated for pain only when patients complained ( table 1 ) . this approach to pain management should be discouraged as much as possible , and routine pain assessments , using either the verbal rating scale or the visual analogue scale , should be encouraged . in our study , the types of analgesics commonly used for cancer patients were weak opioids , such as tramadol and df118 ( 43 % ) , alone or in combination with nsaids ( 32 % ) . strong opioids , such as oral or parenteral morphine , pethidine , and pentazocine were used by only 19.5 % of the respondents , while 2.4 % of the respondents used other modalities ( figure 5 ) . while the correct use of the who analgesic ladder results in successful pain management in 90 % of patients ,19 a number of studies have reported inadequate pain control in 40 % 70 % of patients ,15,20 resulting in the emergence of a new type of epidemiology , that of failed pain control , caused by a series of obstacles preventing adequate cancer pain management . thus , the current thinking is focused on the combination of therapeutic agents , particularly in situations of failed pain control . an in - depth understanding of the pathophysiology and the various cellular mechanisms of pain in cancer patients has lent support to the use of combined therapeutic agents .14,15 some cancer patients have responded well to a combination of opioids and antidepressants . other combinations have been tremendously successful , including opioids and corticosteroids , opioids and anticonvulsants , and opioids and nsaids . the medical practitioners in our study may not have been conversant with these combinations , which may be why they did not report the use of these combination therapies . concerning the action to be takenif the first attempt at treating cancer pain failed , 44 % of the respondents would give stronger analgesics , 35 % would combine stronger and mild analgesics , 17 % would reassure the patient , and 4 % would use a non - drug modality , such as physiotherapy or psychotherapy ( figure 6 ) . thus , our findings suggest that the majority of the medical practitioners in this survey ( 79 % ) tend to follow the who analgesic ladder , with some practicing multimodal pain management . the practice of giving stronger analgesics may seem to be good , but this may also lead to increased side effects and may encourage opioid tolerance . consequently , it may be preferable to combine a strong and mild analgesic in order to achieve better pain relief in cancer patients . the doses of the analgesic should be titrated against the patient s pain , gradually increasing until the patient is comfortable .21 each dose should also be given before the effect of the previous dose has fully worn off . that way , it is possible to relieve pain continuously , though rescue doses for breakthrough pain may have to be given at intervals in addition to the regular pain treatment schedules .21 although other sophisticated modes of delivery are available in developed countries , we found that most respondents in our study used opioids and nsaids via the oral and intramuscular routes only . this finding is similar to an earlier study by amanor - boadu et al among surgical residents at the university college hospital , ibadan , in south - western nigeria .22 they concluded that the residents knowledge of cancer pain management was deficient , and they recommended a workshop approach for training on cancer pain management . consequently , concerning the perceived limitations to adequate cancer pain management , 54 % of our respondents felt that there was poor knowledge of cancer pain management among medical practitioners . this is a surprising admission among medical practitioners who are expected to be very knowledgeable about all the modalities of patient management . some of the respondents ( 22 % ) were of the opinion that patients arrive at the hospital with already advanced stages of cancers and , as such , the respondents view this late presentation as a barrier to adequate cancer pain management because there is very little time to achieve optimal pain control . even if a patient presents with an advanced tumor , potent analgesics should be offered to the patient to achieve optimal pain relief in the shortest possible time . in our study , while 16 % of the respondents were afraid of serious drug side effects , about 9 % of the respondents reported the non - availability of stronger analgesic drugs ( figure 7 ) . the fear of opioid side effects seems to be a common limitation to the use of opioids . the most commonly feared side effects are usually respiratory depression , as an immediate side effect of parenteral opioids , and opioid addiction with prolonged use on patients . opiophobia may be a major hindrance to adequate cancer pain management , as seen in 16 % of the respondents in our survey . barriers to the correct treatment of cancer pain have been identified in recent years , and the agency for health care policy and research ( ahcpr ) classified them into three categories : system , professional , and patient barriers .23 system barriers include the low priority given to cancer pain treatment and the legal and regulatory obstacles to the use of opioids for cancer pain . cancer patients run the risk of becoming innocent victims in a war waged against opioid abuse and addiction if the norms regarding the two kinds of use ( therapeutic or nontherapeutic ) are not clearly distinguished . furthermore , health professionals may be worried about regulatory scrutiny and may opt not to use opioid therapy for this reason . system barriers can also be internal ( such as the inadequate or late start - up of palliative care programs ) or external ( such as regulatory excesses and complications ) . in developing countries , system barriers may also include opiophobia , the high cost of opioids , and the problems of geographic dispersion , availability for treatment , and access to opioids .6,24,25 it has been reported that physician barriers to correct cancer pain management are numerous .6,24 these include the use of a disease - based rather than a symptom - based model of care , the lack of physician education and the failure to follow existing guidelines , and the lack of priority given to symptom management . another professional barrier is the establishment of an analgesic level based on the prognosis rather than the severity of pain , and thus , the poor assessment of pain and the lack of proactive questioning about symptoms . likewise , insufficient experience with pain management ( poor knowledge of opioid pharmacology , conversion , equianalgesia , rotation , doses , and ratios for breakthrough pain drugs ) is a professional barrier , as is the fear of patient addiction and analgesic tolerance , the failure to use adjuvants , the failure to consider or to treat opioid side effects , the failure to document information on drugs used , dosages given , timing , breakthrough pain , and laxatives administered , and the failure to follow - up . our findings suggest that the lack of physician education or inadequate knowledge about cancer pain management plays a major role as a hindrance to adequate cancer pain management . this is because 91.5 % of the respondents reported that they had no formal training , while only 8.5 % had received some formal training on pain management . the system barrier of opioid unavailability also acts as a hindrance to adequate cancer pain management , though to a lesser extent , as reported by 9 % of the respondents in this survey . there is inadequate knowledge about the current trends in cancer pain management among the medical practitioners surveyed . although most of the respondents seemed to use the who analgesic ladder , the majority of the medical practitioners surveyed had no formal training on cancer pain management . we recommend that pain management should be part of the curriculum in all medical schools . this formal training should take the form of lectures , seminars , and workshops on cancer pain management . abbreviations : said , nonsteroidal anti - in flammatory drug ; mb , bachelor of medicine ; bs , bachelor of surgery ; fwacs , fellow west african college of surgeons ; fnmc , fellow national postgraduate college ( nigeria ) .\noutput:\n" }, { "from": "agent", "value": "backgroundseveral factors considered to be barriers to cancer pain management have been reported in the past . the knowledge of cancer pain management may be a hindrance to the proper assessment and treatment of pain in cancer patients.objective : this report presents an evaluation of the knowledge and practice of cancer pain management among medical practitioners in ahmadu bello university teaching hospital , shika , zaria.methods : this report involves medical practitioners at the ahmadu bello university teaching hospital who are directly involved in the management of cancer patients . information was obtained using a structured questionnaire , and the data were analyzed using spss ( version 11.5 ) . results : the response rate to the questionnaire was 82 % , with an age range of 23 to 50 years ( mean age , 34.9 ) , and the majority of actual respondents , 55 ( 67 % ) , were male . thirty - six ( 44 % ) strongly agreed that cancer patients require pain relief . yet only 40 % of the respondents routinely conducted pain assessments among cancer patients , while 51 % only treated when patients complained of pain . concerning the type of analgesic commonly used for cancer patients , 43 % used weak opioids , 32 % used nsaids , and only 20 % used strong opioids . seventy - five respondents ( 91.5 % ) had no formal training on pain management.conclusion : the knowledge of pain management for cancer patients among medical personnel at the ahmadu bello university teaching hospital appears to be elementary . we recommend that formal training in the form of lectures , seminars , and workshops on cancer pain management should be part of continuing medical education in low - resource settings like the ahmadu bello university teaching hospital ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: walking and maintenance of balance in human beings depend on the complex integration of information coming from the visual , vestibular , and somatosensory systems1 ,2,3 . plantar cutaneous receptors located on the plantar side of the foot provide somatosensory information for the body4 , 5 . the stimuli coming from the bottom of the foot are important in terms of preventing balance problems and sustaining healthy walking1 . in recent studies , it has been determined that the obesity prevalence has increased in children and adults to a serious level6 . one of the concerns with the high prevalence of obesity is its association with an increased risk of falling . each year , obese adults fall almost twice as frequently ( 27 % ) as their nonobese counterparts ( 15 % ) 7 . an important reason for falling in obese people is the loss of balance due to the disrupted plantar sensitivity of the foot8 . the feet provide important sensorial information for balance and walking and help to sustain stability . the proprioceptive system is extremely important in ensuring the necessary balance control for standing and walking . the sensorimotor system uses the information coming from foot arches , joint capsules , intrinsic muscles , and cutaneous mechanoreceptors on the plantar surface of the feet to regulate the motor movement . situations that cause problems in the functioning of this information may influence sensorimotor organization in a negative manner9 , 10 . these effects caused by obesity are explained by the effect of the weight on the foot structure . there are studies in the literature reporting that excessive weight and increased body mass index are related to a decrease in the arch of the foot and pes planus , decrease in the joint movement distance , chronic heel pain , nonspecific foot pain , tendonitis , changes in the plantar fat pad , biomechanical changes in the feet , and increased plantar pressure while standing and walking13 , 14 . gender and age , as well as increases in weight are important factors influencing the functioning of the somatosensory mechanism . the plantar surface cutaneous sense , which is extremely important in ensuring static and dynamic balance control , may lead to a decrease in the functioning of the sensory systems with increasing age9 . similarly , it has been demonstrated that there are differences between foot morphology and plantar pressure in women and men10 , 15 . although there are studies in the literature showing how plantar pressure characteristics in children and the elderly are influenced , there are few studies on how the plantar sense is influenced in different age groups and those that have been done have had limited numbers of cases in them . similarly , the studies that have examined the effects of an increase in weight on plantar sensitivity in different age groups are extremely insufficient . the first aim was to demonstrate how plantar sense is influenced in women with different body mass indices . the second aim of the study was to demonstrate the change in plantar sensation in healthy women according to age . this study is important because it was conducted to show the change in plantar surface cutaneous sensation ( tactile sensitivity ) in healthy individuals over the age of 20 . our hypothesis was that plantar sensation decreases to an important level in healthy women with increasing age and weight . healthy female volunteers who accompanied patients to family clinics in the county of mudurnu in the province of bolu formed the population of the study . in a strength analysis performed to determine the sample size , it was determined using the epi info 7 ( 7.1.1.14 ) software that at least 100 women needed to be included in the study to obtain a strength rate of 80 % with a confidence limit of 95 % and an error rate of 0.05 . the criteria for being included in the study were being over the age of 20 , being female , having no communication problems , and volunteering to participate in the study . the criteria for not being included in the study were having a foot plantar area dermatologic disease having edema in the feet ; having a neurological , cardiopulmonary and / or musculoskeletal disease having a disease related to diabetes or peripheral neuropathy ; or having a foot injury in the past year . the ethics committee of dzce university ( dzce university clinical research ethics committee , decision number : 2015/36 ) approved this research . the demographic characteristics of the patients ( age , height , weight , gender , body mass index ( bmi ) ) were recorded . the heights of the patients were measured with a wall strip when they were standing in bare feet . the weights of the patients were measured using a fakir hercules scale after they removed as much clothing as possible . statistical analyses were performed by considering the age and bmi values of the individuals . the individuals were divided into 3 groups according to their bmi values as fallows ; normal weight ( bmi : 18.524.9 kg / m ) , overweight ( bmi : 2529.9 kg / m ) , as follows : and obese ( bmi : 30 and over kg / m ) . similarly , the individuals were also divided into 3 groups according to their age distributions 2044 years old ( n = 50 , 24.6 % ) , 4564 years old ( n = 115 , 56.6 % ) , and 65 years old and over ( n = 38 , 18.7 % ) . all subjects were questioned regarding their level of education , marital status , chronic diseases , current use of tobacco , and current use of alcohol . foot pain was examined in the subjects with a visual analog scale ( vas ) . the individuals were asked to evaluate their level of pain on a 10 - cm line with numbers indicated on it from 0 to 10 at 1 - cm increments . zero ( the left point ) represented no pain , 10 ( far right point ) represented the most severe pain , and the middle represented mild pain . the point where the individual marked was measured with a ruler , and the value was recorded as the pain score . in order to assess plantar cutaneous sensation ( tactile sensitivity ) , semmes - weinstein monofilaments apply bending stress to the skin and create a sense of pressure , and the amount of pressure they apply is indicated by numbers ranging from 1.65 to 6.65 . the highest monofilament value is the hardest filament , which can only be bent with difficulty . the individuals were asked to lie on their backs with their feet bare and their eyes open . a researcher , who was a physiotherapist , stood by the individual and applied the monofilament at a 90 - degree angle for 1.5 seconds ( s ) to 7 areas on the plantar surface of the foot where the load was applied on the individual and which was inclined to ulceration ( first toe , fifth finger , first and fifth forefoot , hindfoot , medial and lateral sides of the foot ( mid - foot ) ) , and the patient was asked whether she felt it or not . this was repeated for both feet with each monofilament in all areas ( fig . planter are sensory test with a monofilament statistical analyses were performed using the pasw statistics ( ver . the definitive statistics were determined by using average and standard deviation values for continuous variables ; for categorical variables , frequency and percentage values were used . the age groups of the individuals included in the study ( 2244 years old , 4564 years old , 65 years old and over ) , bmi groups ( normal , overweight , obese ) , frequency of pain , and relations between monofilament thicknesses in different areas were evaluated with the relevant chi - square analysis . the kruskal - wallis test was used in comparing the bmi and age groups in terms of vas scores , and differences between the groups were examined with the dunn s test . the average age of the individuals who participated in the study was 52.5913.05 years , the average bmi value was 29.05.63 ( kg / m ) . fifty - six ( 27.5 % ) of the individuals had normal weights , 67 ( 33 % ) were overweight , and 80 ( 39 % ) were obese . the majority of the individuals ( 78.8 % ) were housewives , and the educational levels were low ( 67.5 % ) . tobacco and alcohol use were extremely low ( % 10 and % 2 of the individuals reported tobacco and alcohol use , respectively ) . sixteen ( 7.9 % ) individuals had cholesterol complaints , while 186 ( 91.6 % ) individuals did not ( table 1table 1 . sociodemographic characteristics of the subjectsn = 203x ssage ( years , x ss ) 52.596113.05 height ( m , x ss ) 1.58360,06 weight ( kg , x ss ) 73.040913.51 body mass index ( kg / m , x ss ) 29.015.63 n % bmi groupsnormal5627 .59 overweight6733obese8039age groups25445024 .6456411556.665 and over3818 .7 professionnot working115 .4 officer136 .4 employee136 .4 freelance42housewife16078 .8 other21educational levelprimary13767 .5 secondary school94 .4 high school 83.9 university188 .9 other94 .4 illiterate2210 .8 current use of tobaccoyes2210 .3 no18189 .2 current use of alcoholyes42no13968 .5 cholesterolyes167 .9 no18691 .6 ) . the frequency of pain was 9 ( 23.7 % ) in the 2544 age group , 37 in the 4564 age group ( 54.4 % ) , and 16 ( 51.6 % ) in the individuals who were over the age of 65 . when the age groups were compared in terms of the frequency of pain , the pain frequencies of the age groups comprising individuals 45 years old and over were similar ; however , the frequencies were significantly high when compared with that for the 44 years old and below age group ( p 0.05 ) . in addition , the pain frequency was 38.7 % ( 12 people ) in the normal weight group , 44.4 % in the overweight group ( 20 people ) , and 49.02 % ( 30 people ) in the obese group . no significant differences were determined between the bmi groups in terms of the frequency of pain ( p 0.05 ) . however , when the bmi groups were compared in terms of vas scores , there was a significant difference only between normal and obese individuals ( p 0.05 ) . the severity of pain in obese individuals was higher than that in normal weight individuals ( p 0.05 ) . when the age groups were compared , the severity of pain ( vas ) in 44 years old and below age group was significantly lower ( p 0.001 ) ; however , no significant differences were found in the age groups comprised of individuals over 45 years old and older ( p 0.05 , table 2table 2 . the level of pain according to age and bmi group distributionbmi groupsage groupsnormal weight ( n = 35 ) overweight ( n = 55 ) obese ( n = 59 ) 2244 ( n = 36 ) 4564 ( n = 86 ) 65 and over ( n = 27 ) vasx sd ( min - max ) x sd ( min - max ) x sd ( min - max ) x sd ( min - max ) x sd ( min - max ) x sd ( min - max ) 1.421.71 * * ( 06 ) 1.921.64 * * ( 07 ) 2.381.89 * * ( 07 ) 0.881.66 * ( 06 ) 2.401.67 * ( 07 ) 2.141.74 * ( 07 ) * p 0.001 , kruskal - wallis test . * * p 0.05 , kruskal - wallis test . vas : visual analogue scale when the relation between the frequency of pain and the monofilament thicknesses was examined , the frequency of pain in the individuals who felt the 5.17 monofilament only in right monofilament area 2 and left monofilament area 1 was significantly higher ( p 0.05 ) , and there were no significant differences between the 4.17 and 5.07 monofilaments in terms of the frequency of pain in the other right and left areas ( p 0.05 , table 3table 3 . pain frequency and distribution according to monofilament thickness and areamonofilament measurement area monofilament thicknessfoot painyesnoright foot n % n % area14 .175745.66854.45.07541.7758.3 area 2 ** 4.175142.17057.95.071168.8531.3 area 34.175345.76354.35.07942.91257.1 area 44.174743.96056.15.071550.01550.0 area 54.175243.36856.75.071058.8741.2 area 64.175044.66255.45.071248.01352.0 area 74.172841.24058.85.073449.33550.7 left footn % n % area 1 * 4.174037.06863.05.072275.9724.1 area 24.175042.46857.65.071263.2736.8 area 34.175245.26354.85.071045.51254.5 area 44.174443.15856.95.071851.41748.6 area 54.175144.06556.05.071152.41047.6 area 64.174944.16255.95.071350.01350.0 area 74.172845.23454.85.073445.34154.7 * p 0.001 , test . * * p 0.05 , test the sensation frequencies of all right and left plantar areas showed significant changes according to age group for both monofilament thicknesses ( p 0.05 ) . in the statistical analysis , the frequency of feeling the thinner 4.17 monofilament ( i.e. , the plantar sensation ) , showed a significant decrease in right plantar area 4 and left plantar areas 3 , 5 , and 7 . the frequency of feeling the 4.17 monofilament in the other right and left plantar areas was the best in the 2544 age group when compared with the other groups ( p 0.05 , table 3 ) . however , no difference was determined in terms of plantar cutaneous sensation in the 4565 years old age group and the 65 years old and over age group ( p 0.05 , table 3 ) . when the bmi and plantar sensation relation was examined , the individuals whose bmi values were higher in right foot area 7 and left foot area 1 , 4 , and 7 . felt the thicker 5.07 monofilament , ( p 0.05 , table 4table 4 . plantar sensory distribution according to age groupmonofilament measurement areamonofilament thicknessage groups25 - 4445 - 6465 and overright footn % n % n % area 1 * 4.1750 a100 .0105 b91 .332 b84 .25.070 a0 .010 b8 .76 b15 .8 area 2 * 4.1749 a98 .094 b81 .728 b73 .75.071 a2 .021 b18 .310 b26 .3 area 3 * 4.1748 a96 .097 b84 .327 b71 .15.072 a4 .018 b15 .711 b28 .9 area 4 * 4.1748 a96 .091 b79 .120 c52 .65.072 a4 .024 b20 .918 c47 .4 area 5 * 4.1748 a96 .095 b82 .628 b73 .75.072 a4 .020 b17 .410 b26 .3 area 6 * 4.1748 a96 .093 b80 .927 b71 .15.072 a4 .022 b19 .111 b28 .9 area 7 * 4.1737 a74 .061 b53 .014 b36 .85.0713 a26 .054 b47 .024 b63 .2 left footn % n % n % area 1 * 4.1748 a96 .070 b60 .920 b52 .65.072 a4 .045 b39 .118 b47 .4 area 2 ** 4.1747 a94 .098 adifferent superscripts indicate statistically significant differences ( a vs. b , a 0.05 ) . ) . in other areas of both the right and left foot plantar surfaces ( right foot areas 26 , and left foot areas 2 , 3 , 5 , and 6 , respectively ) , there were no significant relations detected between an increase in bmi and the plantar sensation ( p 0.05 , table 4 ) . in other words , no statistical difference was determined in the forefoot areas of the foot except the mid - foot and area 1 ( metatarsal head ) in terms of plantar sensitivity ( p 0.05 ) . it was determined that the probability of the overweight and obese individuals feeling the monofilament in areas where a statistical difference was determined was lower and equal to that of normal individuals ( table 5table 5 . plantar sensory distribution according to bmi groupmonofilament measurement areamonofilament thicknessbmi groupnormal weightoverweightobeseright footn % n % n % area 14.175598.259 b88 .173 a . different superscripts indicate statistically significant differences ( a vs. b , a 0.05 ) . ) . the results of our study showed that , supporting our hypothesis , plantar sensation decreased in healthy women as age and bmi values increased . similarly , it was also determined that the frequency and severity of pain in the feet increased as age increased , and that the severity of pain ( vas ) was higher in individuals who were obese when compared with normal weight individuals . differences have been observed in tactile sensitivity and proprioceptive sensation with increasing age17 ,18,19 . discriminative touch ( i.e. , 2 - point sensation ) has been found to be compromised with aging20 , 21 . the decrease in tactile sensitivity , together with the decreasing stimuli coming from the foot and ankle area , may lead to serious postural stability problems and falling19 . it is an undeniable fact that tactile sensitivity is clinically important and has an important influence on quality of life . a degradation of tactile acuity in aging may be clinically meaningful in that a recent study identified that the loss of 2 - point sensation in the plantar aspect of the toe ( in the sole ) was significantly greater in fallers than in nonfallers22 . the afferent signals coming from the sole cutaneous receptors influence balance and stability and ensure temporal and spatial information23 . these signals play important roles when compensatory actions are needed to maintain continuity of the erect posture . toledo and barela19 observed that the more the proprioceptive system is impaired in elderly subjects , the greater the oscillations of the center of pressure , which reinforced the idea that balance is influenced by the proprioceptive information of the sole of the foot . franco et al. 24 conducted a study and reported that they could not detect or define any peripheral diseases ; however , they observed a lower ability to discriminate two - point pressure in the sole in the elderly when compared with young individuals . conducted a study on 60 healthy older adults ( 65 years old and over ) and in 19 young adults ( 1828 years old ) in which they assessed 2 - point gap discrimination in 5 body areas ( volar forearm , upper and lower surfaces of the forefinger , and plantar and dorsal surfaces of the forefoot ) and reported that there were important losses in older adults when compared with young people in tactile acuity , and the loss was greater25 . perry conducted a study on 95 older adults ( 6375 years old ) and on 7 other adults ( 2326 years old ) and reported that the monofilaments were beneficial when used for assessing age - related insensitivity and that the older adults had plantar - surface insensitivity at an important level when compared with the young adults9 . in our study , plantar surface sensation decreased with increasing age , which is consistent with the studies conducted so far . furthermore , the measurements for right and left foot plantar sensitivity were better in individuals in the 2544 years old group ; however , there was no statistically significant difference between the individuals from the 4565 years old and over 65 years old groups . there were also important decreases in the sensing the 4.17 monofilament in the rear - foot areas of the foot ( area 7 ) , forefoot ( especially right area 4 and left area 3 ) , and mid - foot ( left area 5 ) . we also agree that the monofilaments are beneficial in evaluating age - related insensitivity , which was reported in the study conducted by perry9 . it is possible that there might be decreases in plantar cutaneous sensitivity due to different health problems as age increases ( visual losses , hearing losses , foot problems , neuropathy , etc. ) 21 , 26 . as a matter of fact , the frequency and severity of pain in the foot increased with increasing age in the present study . the frequency and severity of the pain were higher in the individuals who were 45 years old and over . although no statistically significant differences were observed , the severity of pain of the individuals who were 4564 years old was higher than that of those who were 65 years old and over . we consider that this result may stem from the fact that this age group is more active when compared with individuals who are 65 years old and over . it is possible that the social participations and performance of activities that require standing and walking decrease with increasing age due to retirement or various health problems . this situation may also be observed due to the lower extremity pain occurring for any reason or a decrease in mobility . tactile inputs in the skin of the foot are important for body posture awareness27 . the ability to sense them is considered a function that has to be cared for , especially at older ages , and must be regained . for this reason , proprioception exercises that can be performed , especially by young adults and adults , and whether an individual has any health problems or not are of great importance in terms of protecting the quality of life of an individual . similarly , we think that the pain score must be evaluated in individuals who are 45 years old and over , as pain has an important influence on foot functions and proprioception . in the studies conducted so far , it was observed that increased body weight influenced postural stability in a negative way and increased the risk of falling and injuries . an increase in body weight in obese people influences the functioning of the mechanoreceptors on the bottom of the foot with the increase in load during standing and walking in a negative way , and these results in proprioception loss . in other studies , it was determined that high plantar pressure was related to obesity and that plantar pressure was related to plantar sensitivity7 . similarly , it was reported that obesity and an increase in weight in children and adults was related to musculoskeletal pain especially that involving the lower extremity ( knee , feet , and hip pains ) , and led to disability28 . in our study , it was determined that there was a relation between the bmi value and plantar sensation and that plantar sensitivity decreased as bmi increased in healthy adults ( especially in forefoot ( areas 1 and 4 ) and hindfoot areas ( area 7 ) ) . however , no relations were determined between the bmi and in the mid - foot area of the foot ( areas 5 and 6 ) . similarly , foot pain increased with the increase in weight , and there was a significant relation between foot pain and plantar sensitivity . in our study , the frequency and severity of pain in obese individuals were higher when compared with those of normal weight individuals . cimolin et al. 29 conducted a study and determined that the contact areas of the forefoot and mid - foot ( only the medial area ) areas of the foot with the ground were bigger in obese people when compared with those who were not obese , and there were no statistically significant differences in the hindfoot areas . our results show that the load on the feet increased with the increase in weight in healthy individuals especially around the first toe and heel , and this led to a loss of sensitivity in the areas where excessive load was placed . it was also observed that plantar sensitivity was influenced negatively by foot pain in obese people . foot pain may influence the distribution of the load on the bottom of the feet in an individual . for this reason , determination of musculoskeletal system problems of the feet in individuals who gain weight - even if they are healthy - is important . it is also important to apply exercises that will increase proprioception together with assessments for loss of sensation . the lack of detailed evaluation of the load on the feet is the important limitation of our study . there is a need for more studies on how an increase in body weight influences plantar pressure and plantar sensitivity . the important limitation of our study was the fact that the distributions of the load on the feet were not assessed by using different methods . if the relation between the distribution of the load on the feet , especially in individuals who gained weight , and plantar sensitivity was assessed , the relation between foot pain , the distribution of the load on the feet , and plantar sensitivity could be assessed better . in obese individuals with higher levels of pain severity in particular , determination of the distribution of the plantar load on the feet might be important in terms of observing what kind of changes occur when compared with normal weight individuals . more studies must be conducted in which the relation between the distribution of the load on the feet and plantar sensitivity in individuals with different bmi values is investigated . another limitation of our study was the examination of the pain as foot pain . examination of the localization of the foot pain would facilitate determination of the areas of plantar sensation losses and ensure better interpretation of the relations between them . since the determination of these relations was not the primary purpose of our study , the fictionalizing of the study was made on foot pain . however , there is need for further studies in which foot pain is determined locally and the plantar relations are examined . determining the influence of pain on plantar sensation will be important in terms of determining and preventing losses of sensations and the balance and walking problems stemming from them in individuals who have foot pain due to various reasons . the results of our study demonstrate that although an individual may be healthy , there might be increases in foot pain and decreases in foot plantar cutaneous sensation as age and body mass index increase . when the importance of the relations between foot sensation and mobility and falling is considered , provision of plantar sensation training is considered to be important for individuals to maintain their quality of life and decrease the risk of injuries . there is a need for further studies in which different methodologies are used to examine this issue . the authors declare that they have no potential conflicts of interest with respect to the research , authorship , and / or publication of this article .\noutput:\n" }, { "from": "agent", "value": "[ purpose ] this study was conducted to examine the effects of age and body mass index on plantar cutaneous sensation in healthy women . [ subjects and methods ] two hundred and three healthy female volunteers over the age of 20 were included in the study . the statistical analyses were performed by considering the age and body mass index values of the individuals . the individuals were divided according to their ages and body mass index values . foot pain was measured with a visual analogue scale and plantar cutaneous sensation using semmes - weinstein monofilaments . [ results ] fifty - six ( 27.5 % ) of the participants had normal weights , 67 ( 33 % ) were overweight , and 80 ( 39 % ) were obese . statistical analysis revealed that as age and body mass index values increased , plantar sensitivity decreased and the frequency and severity of pain increased . [ conclusion ] it is possible that healthy women may experience a decrease in foot plantar sensation with increasing weight and age . if women do not have any health problems , proprioception and sensory training must be focused on in order to prevent balance and falling problems ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: patients with ckd and esrd suffer from an impaired immune response . according to previous studies , this continuous inflammatory state predisposes patients to cardiovascular diseases and acute infectious complications , two of the main causes of death in this population . despite proper pharmaceutical therapy and / or adequate hemodialysis , mortality rates in these groups of patients are much higher than in the general population and it seems that the dysfunction of the immune system plays a key role in the pathogenesis of many disorders associated with renal failure . the tumor suppressor genes p53 and rb are possibly the two most known and well - studied genes in this particular category . these genes control the g1s phase of the cell cycle transition and their downregulation is absolutely necessary in order for the cell to duplicate . whenever for example there is a dna damage or genome instability , complex molecular networks mediated by these two genes halt the cell cycle in order for the dna to be repaired before duplication . apart from controlling the cell cycle progression , p53 has also the ability to induce apoptosis . another important point of their function is that the vast majority of cancer cells exhibit either turned off , or mutated p53 and rb genes . in a previous study , we found that telomerase activity , an enzyme that provides an almost unlimited proliferation capacity when active , is decreased in peripheral blood mononuclear cells ( pbmcs ) from dialysis patients , when compared to healthy individuals . simultaneously , this activity was inversely correlated with serum tnf - concentration in the population studied . in the present study , immune cells belonging to renal patients were examined from a different perspective . since telomerase , an enzyme that deals with cell division , is less active in renal failure , the transcription patterns of two very important genes implicated in cell division were determined . thirty different individuals were chosen , ten from each of the following categories : healthy controls , ckd patients , and esrd ( dialysis ) patients . pbmcs were purified and cultivated in four different conditions : ( i ) without the addition of any factor other than culture medium with antibiotics ( plain culture ) , ( ii ) with the addition of lipopolysaccharide ( lps ) , ( iii ) in presence of c - reactive protein ( crp ) , and ( iv ) with the addition of lps and lipoxin a4 ( lxa4 ) . lps or endotoxin is a molecule located at the cell wall of gram negative bacteria and has the ability to promote a strong inflammatory response . crp is one of the most well - investigated acute phase proteins and its main role is to bind to phosphocholine expressed on the surface of dead or dying cells or bacteria , in order to activate the complement system and the phagocytosis by macrophages . the aim of the study was to explore any possible differences in the transcription of both tumor suppressor genes before and after the various cultivation conditions , among the different study groups . the inflammation status of every individual included in the study was assessed by the determination of interleukin 6 ( il - 6 ) , il - 10 , c - reactive protein ( crp ) , and tnf - in blood serum . the population studied consisted of three groups : ten healthy individuals ( normal controls ) , ten chronic kidney disease ( ckd ) nondialysis patients , and ten dialysis patients with end stage renal disease ( esrd ) , subjected to hemodialysis several times in a week . age , sex , gfr , and other relevant data of the three groups are shown in table 1 . an interview was conducted with every person before his / her admission to the study . through this interviewit was defined if that person was a smoker or not , while a blood glucose value of 110 mg / dl in three different measurements was used as the definition of diabetes . hypertension was defined through a blood pressure mean value of 140/80 mmhg or antihypertensive treatment while in order to decide if a person suffered from atherosclerosis he / she had to have a history of angina , and / or vascular interventions , or a history of any cardiovascular event ( e.g. , past myocardial infarction ) . the new york heart association definitions were used for the assessment of heart failure in the population studied . the ckd group consisted of patients with a declined renal function and decreased gfr ( gfr values from 15 to 60 ml / min , calculated with the cockcroft - gault formula ) not needing dialysis , and the dialysis group comprises of patients with totally diminished kidney function depending on dialysis sessions several times a week . the mean value of the time in months that these patients had been subjected to dialysis sessions was 63.88 ( st . the dialysis filter was made out of cellulose , while in six patients a synthetic filter was used . in nine dialysis patientsin all groups a 15 ml heparinized and a 5 ml nonheparinized blood samples were collected from each patient , for the preparation of pbmcs and serum samples , respectively . in dialyzed patients , pbmcs were obtained by a ficoll - hypaque ( histopaque 1077 , sigma aldrich , st louis , mo . , usa ) gradient density centrifugation ( 400 g for 30 min ) . the mononuclear layer was then collected and washed 3 times in pbs , and finally four aliquots containing 410 cells were transferred into eppendorf tubes . blood serum was isolated by centrifugation of the 5 ml non - heparinized blood vial in 3200 rpm for 25 min . the quantitative determination of crp was assayed by particle - enhanced immunonephelometry on a behring nephelometer ii ( dade behring , deerfield , illinois , usa ) . il - 6 , il - 10 and tnf - serum levels were quantified with a commercial sandwich enzyme immunoassay technique based on a monoclonal - polyclonal antibody pair ( r & d systems , minneapolis , minn . the vials containing the medium with the necessary supplements for the cultures were preprepared in order for the cells to be placed into cultivation immediately after isolation . fifteen ml polypropylene round - bottom tubes ( falcon , becton dickinson , lincoln park , n.j . , usa ) were used and each culture was adjusted to a concentration of 210 cells / ml in rpmi 1640 culture medium ( sigma aldrich , st louis , mo . , usa ) supplemented with 1 % heat - inactivated fetal bovine serum ( sigma aldrich ) , 5.000 u / ml penicillin and 3.000 g / ml streptomycin . the four culture sets contained the following additives : ( a ) controls without any additive ( plain cultures ) , ( b ) lps 5 g / ml ( sigma - aldrich , escherichia coli 0111 : b4 ) , ( c ) human crp 50 g / ml ( usbiological , swampscott , massachusetts , usa ) , ( d ) lps 5 g / ml and 10 nmol / l lxa4 [ 5 ( s ) ,6 ( r ) - lipoxin a4 , cayman chemical , ann arbor , michigan , usa ) ] . the incubation lasted for 24 h at 37c in a humidified atmosphere containing 5 % co2 , and the falcon tubes had loosened caps . cells were collected by centrifugation at 3,000 g for 5 min at 8c and stored at 80c while the supernatant was discarded . rna was purified from pbmcs with nucleospin 96 rna kit ( macherey - nagel 's gmbh & co. kg , dren , germany ) , according to the manufacturer 's instructions . reverse transcription pcr was performed on rna purified samples with superscript iii reverse transcriptase ( invitrogen , carlsbad , ca , usa ) as described in the instructions ' manual .410 cells per sample were used for the rna purification . from the isolated rna ,11.5 l per sample were transcribed and the resulting cdna was used in the real - time pcr procedure . real - time pcr was performed on sds system 7300 ( applied biosystems , foster city , ca , usa ) . assays - on - demand 20x assay mix of primers and fam dye - labeled taqman mgb probes ( applied biosystems , foster city , ca , usa ) were employed to calculate the relative expression of p53 and rb ( assay i d : hs00153349_m1 and hs00153108_m1 resp . ) . predeveloped gapdh ( glyceraldehyde 3 - phosphate dehydrogenase a housekeeping gene ) taqman assay reagent was also used for endogenous control . each experiment was performed under the exact same circumstances and in duplicates in order to be able to correct any possible mistakes . to avoid any bias , rna isolation and real time pcr experiments were performed with multiple samples simultaneously and the samples were later on categorized with respect to the group that each belonged to , after each reaction was completed . the ct ( cycle threshold ) values obtained at the end of the procedure were transferred to rest software ( relative expression software tool , v2 .0.7 , copyright 2008 , corbett research pty . ltd . ) for the relative expression to be calculated . each sample was tested in duplicates . since the relative quantification method was used for the assessment of the gene transcription rates , only pair wise comparisons could be made . these comparisons are shown in table 2 with the differences in expression , the difference factor and the statistical significance . the term difference factor stays for the difference in gene expression between the two groups . ct values calculated from the real time pcr experiments were analyzed by rest software with the first group in each pair being always considered as the control group while the second one is the group to be tested . difference factor states the increase or decrease of the expression in folds . if for example the result between two groups is a downregulation of p53 by a 0.1 factor , then the second group exhibits a tenfold decrease in p53 expression when compared to the first group . spss from ibm ( armonk , serum inflammation markers were analyzed by the one way anova test , while the statistical significance of the real - time pcr results was calculated by rest software that uses the hypothesis test through many randomizations techniques . the mean values and the statistical analysis of the inflammation markers measured in each group are shown in table 1 . only tnf - was found to be significantly elevated in both patient groups as compared to the healthy controls . after statistical analysis ( one - way anova tool ) , tnf - seems to become elevated as the disease progresses . the dialysis patients had higher concentrations than the ckd ones , while the lowest values were observed in the control group ( p 0.05 ) . as stated before , for the assessment of the gene transcription rates , the relative quantification method was used and thus , only pair wise comparisons could be made . the expression status of both p53 and rb was found to be in the same level in all three groups in the cells immediately after purification ( before culture ) . after cultivation of pbmcs from control samples , p53 demonstrated a decrease in expression by 5-fold or higher . the expression of p53 in the ckd and the dialysis groups was less decreased than in the control group in the corresponding cultivations . this was more evident in the dialysis group where the cells in the plain cultures demonstrated the same p53 expression as cells before culture . similar results were obtained when the expression of rb was measured after the completion of each culture . with the progression of the disease , the gene demonstrated remarkably higher transcription rates in the corresponding cultures in a more obvious way than p53 . in the dialysis group , the transcription status of rb was the same before cell culture as well as after the plain cultivation and after the lps culture . these figures are divided by the group each sample belonged to and they are the outcome of the pair wise comparisons depicted in table 2 . as explained thoroughly in section 2 due to the use of the relative quantification method , a certain gene 's expression is calculated only through pair wise comparisons performed with a particular computer software ( rest ) . the bars show the differences in expression between the different conditions and their height does not correspond to a certain numerical value . rb and p53 are very important tumor suppressor genes controlling the cell cycle , being downregulated or inactivated in order for a cell to divide . in the present study , there were no differences in the transcription status of rb and p53 in freshly isolated pmbcs ( before culture ) among the patients and the healthy controls . however , differences were observed after the completion of four different sets of cell cultures either with or without any additives . both genes were highly downregulated in healthy controls independently of the culture conditions , whereas they were more actively transcribed in ckd patients and even more in the dialysis group under the respective culture conditions as in the healthy controls . it is very likely that lymphocytes can promptly respond to environmental changes , by regulating gene transcription in a way that the cell cycle is not inhibited in its progression . this is very important for the pmbcs when for example an infectious agent must be eliminated . a large percentage of renal patients suffer from a chronic inflammatory state and bear an impaired immune function . here we demonstrated that tnf - serum concentration increases as the disease advances , with the dialysis patients exhibiting the highest tnf - concentrations . in the same time , both patient groups and especially the dialysis group exhibited a limited capacity in regulating p53 and rb expression in vitro . both genes andmainly rb demonstrated high transcription levels in vitro , even when lps or crp were present . the transcription rates of these very important tumor suppressor genes are a very strong indication that lymphocytes from dialysis patients had become senescent , a fact that if true , prohibits these cells from dividing , even in the presence of toxic stimulants . in the culture containing lps , 30 minutes after the onset , an anti - inflammatory agent , lxa4 was added . the question was as how a molecule that inhibits the progression of inflammation could influence the transcription of the two genes . in both , healthy and ckd lymphocytes , the lxa4 culture yielded higher transcription rates of p53 and rb within the same group , whereas the opposite was observed in the dialysis group . in the presence of lps alone , pbmcs from the first two groups downregulated rb and p53 , probably because they recognized a threat in their environment , and they should become activated and proliferate in order to eliminate it . in the dialysis group , however , the lps culture exhibited higher transcription rates for both genes , when compared to the lxa4 culture , showing that these immune cells can not respond properly in the presence of a toxic factor , a sign of immune system dysfunction , as observed in the dialysis group . levels of p53 in cells not undergoing any kind of stress are kept low through a continuous degradation procedure . here we demonstrated that p53 exhibits the same transcription level in all three groups of the population studied . so if we make the assumption that healthy cells are unstressed cells , then every cell in the before culture condition exhibits the same , unstressed transcription level . though the transcription before culture is stable the differences in the after culture experiments are vast . although this is more evident in rb 's transcription , it can also be seen in p53 's case . one can not easily ignore the fact that although healthy plain culture cells exhibit a decreased expression of p53 , dialysis plain culture cells exhibit exactly the same level of expression . in other words , it is very likely that expression of p53 becomes deregulated as the disease advances . ofcourse we are not in the position to know what exactly is going on in the protein level , but the evidence we present can not be easily ignored . these results do not serve as strong evidence of our hypothesis but they clearly serve as hard indications . one can not oversee easily the fact that dialysis cells exhibit high p53 transcription levels even after culture , which means that more p53 protein is produced when compared with healthy cells under the same conditions . it must also be stated that western blot experiments were not performed because we mainly wanted to glimpse at the mrna and not the protein level of these patients , and because we had budget issues . it is very likely though , that we will incorporate these methods in our future experiments . as stated before , there have been numerous scientific reports showing that a major problem for dialysis patients is chronic inflammation . the major cause of death to this group of patients is for example cardiovascular disease , which can be caused and / or accelerated by chronic inflammation . a state of chronic inflammation is evident by either elevated proinflammatory cytokines ( il - 1 , il - 6 , tnf - , etc . ) or elevated acute phase proteins ( crp , albumin , fetuin - a , etc . ) . while there were not any statistical differences between the serum concentration of il - 6 , il - 10 , and crp , the finding that tnf - becomes elevated as the disease progresses is very important and can not be ignored . it must also be stated that there was no significant statistical correlation between age , sex , smoking , diabetes , hypertension , and so forth and / or any of the serum markers ' concentration ( data not shown ) . in this study , we demonstrated strong indications that immune system cells from patients suffering from renal failure have lost their plasticity in regulating the expression of two very important genes which play pivotal roles in the progression of the cell cycle . tnf - stimulates lymphocytes to proliferate and differentiate when a threat is present in their environment . it is very likely that this constant stimulation causes these cells to become exhausted and senescent . if other laboratories around the world are encouraged by this research to investigate more thoroughly the molecular mechanisms underlying ckd 's immune system impairment we will soon uncover these complex molecular pathways . chronic inflammation and immune system dysfunction have been evaluated as major factors in the pathogenesis of ckd and end stage renal disease ( dialysis patients ) , contributing to the high mortality rates observed in these populations . there have been a few studies indicating as well , the emergence of cellular senescence in pbmcs isolated from dialysis patients . the primary thoughts behind this research were to investigate two classic tumor suppressor genes in order to see if kidney disease and / or inflammation can influence their expression . since not so many studies have been published around this issue we consider it as one of the first steps in uncovering how and in what degree renal failure is associated with inflammation and cell cycle . of coursemuch more studies are required for this goal to be achieved but our results are solid , providing strong indication that something is wrong in the proper progression of the lymphocytes ' cell cycle in patients with kidney failure . our only wish is that our study will provide other scientists with substantial motive in order to trigger them to investigate these molecular pathways through and through . in the present paper , it has been demonstrated that pmbcs from ckd and from dialysis patients fail to regulate the p53 and rb gene transcription as a response to environmental changes . this evidence of molecular senescence in the lymphocytes of renal patients is a matter of further investigation in order to clarify reasons causing the respective immune system impairment . if in the end constant inflammation proves to be the underlying cause under the defense system 's dysfunctions , then proper and targeted anti - inflammation therapy must be incorporated in renal patients ' therapy .\noutput:\n" }, { "from": "agent", "value": "patients suffering from renal failure exhibit an impaired immune system function . we wanted to investigate the transcription of the tumor suppressor genes p53 and rb to record , if these cells could be stimulated in vitro in order to divide , after the addition of antigenic and inflammatory factors . this expression was measured by real - time pcr in peripheral blood mononuclear cells ( pbmcs ) from three different groups : ten healthy individuals , ten patients with chronic kidney disease ( ckd ) , and ten dialysis patients with end stage renal disease ( esrd ) . the transcription rate of these genes was also measured after the cultivation of pbmcs under four different conditions : just with the culture medium , with lipopolysaccharide ( lps ) , with c - reactive protein ( crp ) , and with lipoxin a4 ( lxa4 ) - lps . our results show that in most cases after the cultivation with additives , the transcription levels were higher in dialysis patients compared to those of the other two groups . our findings serve as indications of cellular senescence on a molecular level , while it seems that these cells are less easily stimulated in vitro in order to duplicate ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: ossification of the posterior longitudinal ligament ( opll ) is a common cervical disease that can cause stenotic changes in the spinal canal and consequent cervical myelopathy . typically , patients with cervical opll complain of neck pain in their daily lives but lack any significant neurologic symptoms . additionally , individuals with spinal cord encroachment without myelopathy due to opll are susceptible to spinal cord injury ( sci ) 10,21 ) . these patients might exhibit myelopathic symptoms with even minor trauma , such as falls and blunt head injuries16 ) . therefore , cord compressive factors alone can not be considered to be the pathogenesis of the myelopathy that is induced by opll . predicting the course of neurological deterioration in patients with opll across their lifetimes is difficult . previous research has identified a variety of potential prognostic factors that can affect outcomes following posterior cervical decompression5 ,30 ) . however , little is known about the factors related to minor trauma that affect prognoses following cervical decompression of opll . in the present study , we investigated the factors that are related to the clinical outcomes of cervical myelopathic patients who underwent posterior decompression surgeries ; these factors included cervical laminoplasty or laminectomy with instrumentation for the treatment of more than three levels of cervical opll . specifically , we evaluated the relationship between minor preoperative trauma and neurological outcome in patients with cervical opll and investigated static compressive factors and intramedullary signal intensities . this study was approved by the local ethical committee and the institutional review board of our hospital . from january 2006 to december 2012 , we treated 194 patients with had ventral cord compression due to cervical disc protrusion or opll . of the 194 patients treated , 108 patients ( 55.7 % ) had ventral cord compressions that involved more than three levels of opll and no bony fractures . thirty - four patients underwent anterior cervical decompression and were excluded from this analysis due to the biases related to surgical factors . seventy - four ( 38.1 % ) patients , including 55 men and 19 women with a mean age of 58.5 ( range 38 - 82 ) , had ventral cord compressive structures that were caused by opll at more than three levels . all 74 patients had cervical myelopathic symptoms and underwent posterior cervical decompression via cervical laminoplasty or laminectomy with fusion for the treatment of myelopathy . myelopathy was defined by disturbances in motor function that were associated with abnormal reflexes , muscle weakness , and sensory disturbances . diagnoses of cervical compressive myelopathy ( ccm ) were confirmed by radiological and mri findings and included at least one \" upper motor neuron \" symptom ( e.g. , spasticity , hyperreflexia , clonus , or positivity for babinski 's sign ) on neurologic examination3 ) . the patients ' ages , genders , durations of symptoms , neurologic deficits , medical conditions [ including diabetes mellitus ( dm ) ] , and radiographic findings were recorded . the patients ' charts were also reviewed for information about each patient that included the cause of injury and the accident to operation interval . the inclusion criteria were admission through the outpatient department or emergency room and cervical myelopathy upon neurological examination . the spinal cord compressions of the patients were observed to be caused by opll that extended to more than three vertebrae . the specific incomplete neurological syndrome termed central cord syndrome was also included in the study and was characterized by greater muscle weakness and / or sensory loss in the upper limbs than in the lower limbs . we excluded patients with one or two levels of segmental opll , other acute traumatic cord injuries with cervical laminar fractures , bony fractures , or dislocations caused by high - energy trauma , discoligamentous injuries , complete neurological injury after trauma , or other confirmed neurological disorders ( e.g. , cerebral palsy , parkinson 's disease , multiple sclerosis , and polio ) . moreover , other exclusion criteria were ossification of yellow ligaments , severe disc herniation , and previous histories of cervical spine surgery . we carefully ruled out tumors , demyelinating diseases , sarcoid lesions , and spinal cord infarcts using electromyography and somatosensory - evoked potentials ( ssep ) or examination of the cerebrospinal fluid . the patients were excluded if they died , could not be located , or their data were missing before the follow - up evaluation . all patients had normal preoperative radiographs , three - dimensional computed tomographies ( 3d ct ) , and high resolution mri using a 1.5 t signa ( siemens medical system ) unit with a surface coil . the radiographic parameters included the type of opll , the maximal spinal canal stenosis , the space available for the spinal cord ( sac ) , cervical lordosis , and intramedullary signal intensity on t2 - weighted mr images . the types of opll were classified as segmental , continuous , mixed , or localized according to the criteria of the japanese investigation committee on the ossification of the spinal ligament34 ) . cervical spine stenosis was measured via the torg - pavlov ratio ( i.e. , the ratio between the sagittal spinal canal diameter and the vertebral body diameter at the same level ) on normal plain radiographs27 ) . the mean value of the measures for c2 - 7 represented the spinal canal diameter for each patient . a computed tomographic ( ct ) scan was performed prior to surgery for each patient . an aquilion one ct scanner ( toshiba medical systems , tokyo , japan ) was used in this series . three - dimensional cts were performed with the patients in neutral cervical positions to avoid neurological deterioration in the cervical myelopathic patients with cervical opll . using axial ct scans , we evaluated static canal stenosis by measuring the maximal spinal canal stenosis and the sac that was caused by the opll ( fig . these parameters were evaluated at the compressed or injured levels of the myelopathic patients with cervical opll . cervical sagittal alignment ( i.e. , the lordotic angle ) was measured based on a lines that were created parallel to the inferior aspect of the c2 body and parallel to that of the c7 body on neutral lateral views according to cobb 's method ( fig .2 ) . using a picture archiving and communication system ( pacs ) , we measured the length of the signal change from one end of the involved region to the other on t2 - weighted sagittal images ( fig . we evaluated the increase in si at the narrowest level of the spinal cord as follows : grade 0 when no high intramedullary si appeared on the t2 - weighted mr images ; grade 1 when a predominantly faint and fuzzy border was present ; and grade 2 when a predominantly intense and well - defined border was present ( fig . the signal intensities of the spinal cords were assessed as follows : grade 0 when no change in signal intensity ( si ) was present on the t2 - weighted mr images ; grade 1 when a slight intensity change was present ; and grade 2 when a bright signal that was clearly distinguishable from that of grade 1 was present30 ) . neurological outcomes were assessed with the recovery scale of the joa score as follows : recovery scale ( % ) = ( postoperative joa score - preoperative joa score ) / ( full score - preoperative joa score ) 100 . we attempted to perform the cervical decompressive surgeries on the patients with neurological deficits as soon as possible . when the spinal cords had been injured within 8 hours , the patients with neurological deficits following minor trauma received high - dose prednisolone according to american national acute spinal cord injury society criteria2 ) . every 45 minutes for 23 hours thereafter , additional doses of 5.4 mg ( kg / h ) were administered . if the injury time exceeded 8 hours , 20 mg of dexamethasone was administered twice daily for the first 3 days , and once daily for the next 3 days . however , cervical extensive laminoplasty was selected based on the neurologic symptoms and the extent of the levels of cord compression including the most narrowed side on the images . open - door laminoplasty was performed based on the dominant symptom or the most narrowed side on the images if there was no dominant symptom . the decompression levels from c3 - 7 or those extending one level cranial and / or caudal to compressive lesions were included . the cervical laminae were exposed laterally to the medial aspect of the facet joints through a conventional midline approach . bilateral gutters were created in the area between the facet joints and the laminae using a high speed drill , and the spinous processes were split sagittally with a high - speed burr . posterior cervical titanium miniplates ( centerpiece , medtronic sofamor danek , memphis , tn , usa ) or hydroxyapatite spacers ( apacerum , asahi optical co. ltd . , tokyo , japan ) were used to keep the \" door \" open . for the opll patients with local kyphosis or segmental instability , we decided to perform cervical laminectomies and fusions as usual and attempted to realignment the local kyphosis using a posterior screw - rod system . following complete decompression of the neural elements , a procedure involving lateral mass screw and rod instrumentation was performed . after surgery , all patients were required to wear miami neck collars or philadelphia braces for a mean period of three months . the patients were postoperatively followed clinically and radiographically with plain and dynamic films at 1 , 3 , and 6 months and every 6 months thereafter . the mann - whitney u tests were used for nonparametric analyses of the differences between pairs of groups , and kruskal - wallis tests followed by mann - whitney u tests were used to examine the differences between the three groups . pearson correlation analysis was performed between joa recovery ratio and ages , duration of symptoms , cervical alignment , cervical stenosis ( pavlov 's ratio ) , maximal spinal canal stenosis , the space available for the spinal cord ( sac ) , preoperative joa score , si length , or postoperative joa score . spearman correlation analysis was performed between joa recovery ratio and gender , opll type , or severity of preoperative signal intensity ( si ) . the correlations between the variables were determined with regression analyses using medcalc version 13.1 ( medcalc , mariakerke , belgium ) . this study was approved by the local ethical committee and the institutional review board of our hospital . from january 2006 to december 2012 , we treated 194 patients with had ventral cord compression due to cervical disc protrusion or opll . of the 194 patients treated , 108 patients ( 55.7 % ) had ventral cord compressions that involved more than three levels of opll and no bony fractures . thirty - four patients underwent anterior cervical decompression and were excluded from this analysis due to the biases related to surgical factors . seventy - four ( 38.1 % ) patients , including 55 men and 19 women with a mean age of 58.5 ( range 38 - 82 ) , had ventral cord compressive structures that were caused by opll at more than three levels . all 74 patients had cervical myelopathic symptoms and underwent posterior cervical decompression via cervical laminoplasty or laminectomy with fusion for the treatment of myelopathy . myelopathy was defined by disturbances in motor function that were associated with abnormal reflexes , muscle weakness , and sensory disturbances . diagnoses of cervical compressive myelopathy ( ccm ) were confirmed by radiological and mri findings and included at least one \" upper motor neuron \" symptom ( e.g. , spasticity , hyperreflexia , clonus , or positivity for babinski 's sign ) on neurologic examination3 ) . the patients ' ages , genders , durations of symptoms , neurologic deficits , medical conditions [ including diabetes mellitus ( dm ) ] , and radiographic findings were recorded . the patients ' charts were also reviewed for information about each patient that included the cause of injury and the accident to operation interval . the inclusion criteria were admission through the outpatient department or emergency room and cervical myelopathy upon neurological examination . the spinal cord compressions of the patients were observed to be caused by opll that extended to more than three vertebrae . the specific incomplete neurological syndrome termed central cord syndrome was also included in the study and was characterized by greater muscle weakness and / or sensory loss in the upper limbs than in the lower limbs . we excluded patients with one or two levels of segmental opll , other acute traumatic cord injuries with cervical laminar fractures , bony fractures , or dislocations caused by high - energy trauma , discoligamentous injuries , complete neurological injury after trauma , or other confirmed neurological disorders ( e.g. , cerebral palsy , parkinson 's disease , multiple sclerosis , and polio ) . moreover , other exclusion criteria were ossification of yellow ligaments , severe disc herniation , and previous histories of cervical spine surgery . we carefully ruled out tumors , demyelinating diseases , sarcoid lesions , and spinal cord infarcts using electromyography and somatosensory - evoked potentials ( ssep ) or examination of the cerebrospinal fluid . the patients were excluded if they died , could not be located , or their data were missing before the follow - up evaluation . all patients had normal preoperative radiographs , three - dimensional computed tomographies ( 3d ct ) , and high resolution mri using a 1.5 t signa ( siemens medical system ) unit with a surface coil . the radiographic parameters included the type of opll , the maximal spinal canal stenosis , the space available for the spinal cord ( sac ) , cervical lordosis , and intramedullary signal intensity on t2 - weighted mr images . the types of opll were classified as segmental , continuous , mixed , or localized according to the criteria of the japanese investigation committee on the ossification of the spinal ligament34 ) . cervical spine stenosis was measured via the torg - pavlov ratio ( i.e. , the ratio between the sagittal spinal canal diameter and the vertebral body diameter at the same level ) on normal plain radiographs27 ) . the mean value of the measures for c2 - 7 represented the spinal canal diameter for each patient . a computed tomographic ( ct ) scan was performed prior to surgery for each patient . an aquilion one ct scanner ( toshiba medical systems , tokyo , japan ) three - dimensional cts were performed with the patients in neutral cervical positions to avoid neurological deterioration in the cervical myelopathic patients with cervical opll . using axial ct scans , we evaluated static canal stenosis by measuring the maximal spinal canal stenosis and the sac that was caused by the opll ( fig . these parameters were evaluated at the compressed or injured levels of the myelopathic patients with cervical opll . cervical sagittal alignment ( i.e. , the lordotic angle ) was measured based on a lines that were created parallel to the inferior aspect of the c2 body and parallel to that of the c7 body on neutral lateral views according to cobb 's method ( fig . using a picture archiving and communication system ( pacs ) , we measured the length of the signal change from one end of the involved region to the other on t2 - weighted sagittal images ( fig . we evaluated the increase in si at the narrowest level of the spinal cord as follows : grade 0 when no high intramedullary si appeared on the t2 - weighted mr images ; grade 1 when a predominantly faint and fuzzy border was present ; and grade 2 when a predominantly intense and well - defined border was present ( fig . the signal intensities of the spinal cords were assessed as follows : grade 0 when no change in signal intensity ( si ) was present on the t2 - weighted mr images ; grade 1 when a slight intensity change was present ; and grade 2 when a bright signal that was clearly distinguishable from that of grade 1 was present30 ) . neurological outcomes were assessed with the recovery scale of the joa score as follows : recovery scale ( % ) = ( postoperative joa score - preoperative joa score ) / ( full score - preoperative joa score ) 100 . we attempted to perform the cervical decompressive surgeries on the patients with neurological deficits as soon as possible . when the spinal cords had been injured within 8 hours , the patients with neurological deficits following minor trauma received high - dose prednisolone according to american national acute spinal cord injury society criteria2 ) . every 45 minutes for 23 hours thereafter , additional doses of 5.4 mg ( kg / h ) were administered . if the injury time exceeded 8 hours , 20 mg of dexamethasone was administered twice daily for the first 3 days , and once daily for the next 3 days . however , cervical extensive laminoplasty was selected based on the neurologic symptoms and the extent of the levels of cord compression including the most narrowed side on the images . open - door laminoplasty was performed based on the dominant symptom or the most narrowed side on the images if there was no dominant symptom . the decompression levels from c3 - 7 or those extending one level cranial and / or caudal to compressive lesions were included . the cervical laminae were exposed laterally to the medial aspect of the facet joints through a conventional midline approach . bilateral gutters were created in the area between the facet joints and the laminae using a high speed drill , and the spinous processes were split sagittally with a high - speed burr . posterior cervical titanium miniplates ( centerpiece , medtronic sofamor danek , memphis , tn , usa ) or hydroxyapatite spacers ( apacerum , asahi optical co. ltd . , tokyo , japan ) were used to keep the \" door \" open . for the opll patients with local kyphosis or segmental instability , we decided to perform cervical laminectomies and fusions as usual and attempted to realignment the local kyphosis using a posterior screw - rod system . following complete decompression of the neural elements , a procedure involving lateral mass screw and rod instrumentation was performed . after surgery , all patients were required to wear miami neck collars or philadelphia braces for a mean period of three months . the patients were postoperatively followed clinically and radiographically with plain and dynamic films at 1 , 3 , and 6 months and every 6 months thereafter . the mann - whitney u tests were used for nonparametric analyses of the differences between pairs of groups , and kruskal - wallis tests followed by mann - whitney u tests were used to examine the differences between the three groups . pearson correlation analysis was performed between joa recovery ratio and ages , duration of symptoms , cervical alignment , cervical stenosis ( pavlov 's ratio ) , maximal spinal canal stenosis , the space available for the spinal cord ( sac ) , preoperative joa score , si length , or postoperative joa score . spearman correlation analysis was performed between joa recovery ratio and gender , opll type , or severity of preoperative signal intensity ( si ) . the correlations between the variables were determined with regression analyses using medcalc version 13.1 ( medcalc , mariakerke , belgium ) . all 74 patients underwent posterior cervical laminoplasty or cervical laminectomy with fusion . the surgical procedures performed included expansive laminoplasty in 51 patients and cervical laminectomy with fusion in 23 patients . the mean preoperative and postoperative joa scores were 9.83.0 and 12.62.8 , respectively ( p 0.05 ) . overall , the mean recovery rate of the joa score was 43.011.7 % ( range 9.1 - 80 % ) , and the neurological outcomes of all patients improved . the mean follow - up time was 152.9 weeks ( range 52.4 - 339.3 weeks ) . of the 74 patients , 60 ( 81.1 % ) exhibited increased signal intensity within the spinal cord on the t2 - weighted mr images , and 14 patients ( 30.6 % ) did not ( fig . the preoperative signal intensities were grade 0 in 14 patients , grade 1 in 35 patients , and grade 2 in 25 patients . the respective preoperative joa scores and recovery ratios ( % ) were 12.11.8 and 52.815.9 % in the 14 si grade 0 patients , 9.52.9 and 49.315.7 % in the 35 grade 1 patients , and 9.03.1 and 28.711.7 % in the 25 grade 2 patients . there was significant a difference in the recovery ratios across the three groups ( p 0.05 ) . the durations of preoperative symptoms ranged from 1 to 90 days ( mean , 19.7 days ) . there was significant correlation between joa recovery ratio and preoperative joa score , grade of intramedullary signal intensity , maximal spinal canal stenosis , sac or dm , whereas no significant correlation between joa recovery ratio and patient age , cervical curvature , duration of preoperative symptoms , opll type , cervical stenosis ( pavlov ratio ) , the length of si , or minor trauma history ( table 1 ) . in this study , initial joa scores correlated significantly with joa recovery ratio ( r = 0.282 , p 0.05 ) ( fig .6 a ) . also , the space available for the sac correlated significantly with the joa recovery ratio ( r = 0.144 , p 0.05 ) ( fig . the change of maximal spinal canal stenosis correlated negatively with the rate of postoperative neurologic improvement ( r = 0.095 , p 0.05 ) ( fig .6 c ) . the preoperative neurological status , the grade of intramedullary signal intensity , maximal spinal canal stenosis , the sac , and dm were significantly correlated with neurological outcome following surgery . thirty - three patients ( 44.6 % ) had sustained minor trauma to the cervical spine . the traumas included 21 falls , 8 whiplash injuries , and 4 instances in which the patients were struck with blunt objects . most of the patients who had suffered trauma were considered to have cervical spinal cord injuries due to hyperextensions . the intervals between the minor traumas and the surgeries ranged from 1 to 23 days ( mean 4.5 days ) . the mean preoperative joa scores were 11.31.9 for the patients who had no history of trauma and 8.03.1 for the patients who had suffered minor trauma , and the difference between these scores was statistically significant ( p 0.05 ) ( table 2 ) . the respective postoperative joa scores and recovery ratios ( % ) were 13.71.8 and 44.915.6 % for the 41 patients with no trauma and 11.33.2 and 40.720.0 % for the 33 patients who had experienced minor preoperatively trauma ( table 2 ) . there were no significant differences in patient age , cervical alignment , length of signal intensity , and sac between the patients with and without trauma histories . also , there was no significant correlation between joa recovery ratio and the presence of minor trauma ( p = 0.310 ) . although the joa scores were initially worse for the patients with minor trauma histories than for the patients who had not experienced trauma before the surgeries , minor cervical trauma had no direct effect on the surgical outcomes of the cervical opll patients . in our study , 3 of 74 patients ( 4.1 % ) developed c5 palsy postoperatively . in one patient , a postoperative hematoma developed within three hours after the surgery , and we performed an immediate removal of hematomathe other two patients experienced full recoveries from the c5 nerve palsies within approximately six months . additionallyhowever , the area of the dural defect was believed to be small , and the csf leakage was cured by simple conservative treatment . one patient required an additional augmentation surgery due to screw dislodgement one year after the posterior decompression and fixation . additionally , three patients experienced superficial wound infections following surgery , but additional surgeries were not required to remove the instrumentation . thirty - three patients ( 44.6 % ) had sustained minor trauma to the cervical spine . the traumas included 21 falls , 8 whiplash injuries , and 4 instances in which the patients were struck with blunt objects . most of the patients who had suffered trauma were considered to have cervical spinal cord injuries due to hyperextensions . the intervals between the minor traumas and the surgeries ranged from 1 to 23 days ( mean 4.5 days ) . the mean preoperative joa scores were 11.31.9 for the patients who had no history of trauma and 8.03.1 for the patients who had suffered minor trauma , and the difference between these scores was statistically significant ( p 0.05 ) ( table 2 ) . the respective postoperative joa scores and recovery ratios ( % ) were 13.71.8 and 44.915.6 % for the 41 patients with no trauma and 11.33.2 and 40.720.0 % for the 33 patients who had experienced minor preoperatively trauma ( table 2 ) . there were no significant differences in patient age , cervical alignment , length of signal intensity , and sac between the patients with and without trauma histories . also , there was no significant correlation between joa recovery ratio and the presence of minor trauma ( p = 0.310 ) . although the joa scores were initially worse for the patients with minor trauma histories than for the patients who had not experienced trauma before the surgeries , minor cervical trauma had no direct effect on the surgical outcomes of the cervical opll patients . in our study , 3 of 74 patients ( 4.1 % ) developed c5 palsy postoperatively . in one patient , a postoperative hematoma developed within three hours after the surgery , and we performed an immediate removal of hematomathe other two patients experienced full recoveries from the c5 nerve palsies within approximately six months . additionallyhowever , the area of the dural defect was believed to be small , and the csf leakage was cured by simple conservative treatment . one patient required an additional augmentation surgery due to screw dislodgement one year after the posterior decompression and fixation . additionally , three patients experienced superficial wound infections following surgery , but additional surgeries were not required to remove the instrumentation . opll is a subtype of diffuse idiopathic skeletal hyperostosis and might increase the risk of sci associated with minor trauma10 ,16,21 ) . the incidence of opll was estimated to be 26 to 38 % in a patient population sustaining acute cervical cord injury without fracture or dislocation of the spinal column18 ) . moreover , fujimura et al. 10 ) reported that the surgical outcomes of patients with trauma - induced myelopathy are inferior to those with myelopathy unrelated to trauma . many experts have recommended that preventive surgery should be performed prior to the onset of myelopathy in patients with opll and potential spinal stenosis due to ossified ligaments . in contrast , matsunaga et al. 19 ) insisted that preventive surgery for patients in whom myelopathies have not yet developed is inappropriate . these authors stated that the frequency of trauma - induced myelopathy decreased in their prospectively investigated group and assumed that this decrease was due to the patients ' efforts to avoid trauma . the question of whether preventive surgery should be performed in patients with opll remains unresolved . in some ( 44.6 % ) of the patients with opll in our seriesthe initial joa scores were worse among the patients who had experienced minor trauma than among the patients who had not experienced trauma prior to surgery ; however , there was no significant difference in the postoperative joa score and the joa recovery ratio among the patients with and without trauma - induced myelopathy . in the initial stage of this research , our assumption was that the presence of minor trauma would exert an unfavorable influence on the surgical outcome . yet , we found that there was no significant correlation between the presence of minor trauma and joa recovery ratio . although the preoperative joa scores of the patients with minor trauma were relatively lower than those of the other patients , their neurological outcomes improved almost to the same level with the other group of patients . we speculate that this results is because other diverse factors , such as the types of injury , the severity of cord compression , or signal intensity changes had an influence on the surgical outcome . future studies can be performed to identify the precise relationship between opll and the clinical outcome of the patients with minor trauma , with the consideration of the variation in magnitude , mechanism , and level of injury as well as therapeutic treatments . many authors have discussed various factors related to the prediction of the surgical outcomes for cervical opll1 ,12,13,19,31 ) . however , the results of many of the previous studies are inconclusive or conflicting . we evaluated the potential prognostic factors of surgical patients with cervical opll and sought to explain the occasional conflicts between our results and those of other studies . it is known that a narrow spinal canal is an important risk factor for the development of cervical myelopathy associated with opll13 ,14 ) . due to the severe cervical stenosis caused by opll , the insufficient decompression of neural tissues is possible . several calculated ratios , including the occupying ratio and the ratio of maximal opll thickness to anteroposterior spinal canal diameter , have been used to indicate the degree of narrowness of the spinal canal in opll15 ) . however , okada et al25 ) . reported that the neurological outcomes of patients with opll do not significantly dependent on maximal cord compression26 ) . our results revealed that the patients with poorer neurological outcomes had narrower sacs than did the patients with better outcomes . onishi et al. 26 ) stated that trauma - induced myelopathy patients have severely narrowed spinal canals . however , in this study , the canal stenoses and sacs of the trauma - induced myelopathic group were not significantly narrower than those of non - trauma myelopathic group . intramedullary spinal cord changes in si on mri might indicate edema , inflammation , vascular ischemia , gliosis , or myelomalacia of the spinal cord22 ,24 ) . intramedullary signal changes in t2 - weight mri are frequently found in patients with cervical compressive myelopathy . although diverse rates ( 29 - 83 % ) of signal changes on preoperative mr images have been reported32 ,36 ) , intramedullary signal changes on mr were observed in 60 of 74 patients ( 81.1 % ) in the present series . moreover , the severity of signal intensity on the preoperative t2 - weighted mr images had a chance of poor improvement after decompressive surgery . according to our results , posterior decompressive surgery might not significantly improve the myelopathic symptoms of patients with severe preoperative high signal intensity in the spinal cord . kawaguchi et al. 17 ) insisted that there was is negative correlation between the recovery rate after cervical laminoplasty for opll and hemoglobin a1 value . it is known that dm not only involves the peripheral nerves but can also affect the spinal cord6 ) . neurophysiologic abnormalities might be present in the spinal cords and the peripheral nervous systems of diabetic patients23 ,35 ) . in the present study , multiple regression analysis revealed that dm was a risk factor for poor prognoses after decompressive surgeries . we believe that dm has many detrimental effects on the microvasculatures of patients with cervical opll . notably , diabetic patients with concomitant with myelopathy due to opll might have experience more unfavorable outcomes than non - diabetic patients . previous research has reported other potential prognostic factors that might affect outcome following after posterior cervical decompression including the patient 's age , symptom duration , shape of the opll lesion , the number of levels that are compressed , the length of si , and the alignment of the cervical spine1 ,4,7,8,12 ) . however , in our multiple logistic regression analysis , the above variables that have been mentioned by other authors were not significantly related to prognosis following decompressive surgery . generally , the neurological improvement of cervical opll by means of posterior decompression surgeries , such as cervical laminoplasty or laminectomy with fixation , may be generated by direct posterior decompression and indirect anterior decompression of the spinal cord due to posterior shifting of the cord . the average incidence of postoperative c5 palsy following cervical decompression procedures for opll is known to be 8.3 % ( range 3.2 - 28.6 % ) 29,33 ) . radcliff et al. 28 ) reported that postoperative c5 nerve palsy might be due to a posterior drift of the spinal cord that is related to wide decompression . others insisted that opll itself is a risk factor for postoperative c5 palsy and that densely adhered opll in the vicinity of the c5 nerve is related to postoperative c5 palsy20 ) . in our study , we did not find an increased incidence of c5 palsy compared to the results of other researchers20 ) , which is why we believe that it is worth the effort to decompress both foraminal stenoses that result from opll . because our study had a retrospective design , there was a lack of clinical data regarding cervical spine mobility , and the sample size was small . moreover , we compared the groups that had and had not experienced trauma - induced myelopathy , the definition of the minor traumatic injury was not completely clear . the types of trauma might be variable because they were dependent only upon the patients ' delineations . rather , we chose an alternative analysis as other authors have previously reported5 ,30,32 ) ; i.e. , independent radiologists categorized the severities of intramedullary sis into three groups according to si . further extended and comprehensive studies will be performed to establish clinical outcomes using the methods described here . neurological outcome is related to preoperative neurological status , maximal cord compression ratio , dm , and intramedullary si , among many other variables . more stable preoperative neurological statuses were associated with better neurological outcomes following the surgeries operation . the si severities on the preoperative t2 - weighted images were negatively related to neurological outcomes . moreover , the patients with no histories of dm and larger sac experienced greater improvement following the surgeries than did the patients with dm and smaller sacs . although the initial joa scores were worse among the minor trauma patients than among those who had not experienced trauma prior to surgery , minor cervical trauma had no direct effect on the surgical outcomes of the cervical opll patients .\noutput:\n" }, { "from": "agent", "value": "objectivespatients with cervical ossification of posterior longitudinal ligament ( opll ) are susceptible to cord injury , which often develops into myelopathic symptoms . however , little is known regarding the prognostic factors that are involved in minor trauma . we evaluated the relationship between minor trauma and neurological outcome of opll and investigated the prognostic factors with a focus on compressive factors and intramedullary signal intensity ( si ) . methodsa total of 74 patients with cervical myelopathy caused by opll at more than three - levels were treated with posterior decompression surgeries . we surveyed the space available for spinal cord ( sac ) , the severity of si change on t2 - weighted image , and diabetes mellitus ( dm ) . the neurological outcome using japanese orthopedic association ( joa ) scale was assessed at admission and at 12 - month follow - up.resultsamong the variables tested , preoperative joa score , severity of intramedullary si , sac , and dm were significantly related to neurological outcome . the mean preoperative joa were 11.31.9 for the 41 patients who did not have histories of trauma and 8.03.1 for the 33 patients who had suffered minor traumas ( p < 0.05 ) . however , there were no significant differences in the recovery ratios between those two groups.conclusionsinitial neurological status and high intramedullary si in the preoperative phase were related to poorer postoperative outcomes . moreover , the patients with no histories of dm and larger sacs exhibited better improvement than did the patients with dm and smaller sacs . although the initial joa scores were worse for the minor trauma patients than did those who had no trauma prior to surgery , minor trauma exerted no direct effects on the surgical outcomes ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: magnesium valproate is an anticonvulsant used in the treatment of epilepsy and bipolar disorder , as well as other psychiatric conditions requiring the administration of a mood stabilizer . chemical structures of magnesium valproate and four of its process related impurities are given in figure 1 . to our knowledge , there is no paper describing an ultraperformance liquid chromatographic ( uplc ) method that allows the separation of magnesium valproate and its impurities in bulk drugs . some articles exist on isocratic liquid chromatographic methods for the determination of magnesium valproate . however , these isocratic methods use short columns and are suitable for assay only since they focus on the main peak . the methods for determination of valproic acid and sodium valproate are also useful for achieving the best results in this work . some of the bioanalytical methods are also available in literature . applying the above methods for the separation of impurities in a bulk magnesium valproate sample gives poor separation . therefore , an attempt was made to develop a new , rapid , and sensitive method for the determination of magnesium valproate and its process related impurities . to access the reproducibility and wide applicability of the developed method , it was validated as per international code of harmonization norm , which is also mandatory . this paper also deals with the validation of the developed uplc method for the assay of magnesium valproate from its bulk and pharmaceutical dosage form . ( rajkot , india ) has provided magnesium valproate and its process related impurities working standards and samples . ammonium dihydrogen orthophosphate for hplc , orthophosphoric acid ( hplc grade ) , and hplc grade acetonitrile were purchased from spectrochem pvt . this system consists of a binary solvent manager , multiple wavelength ultraviolet detector , sample manager , and column oven connected to a multi - instrument data acquisition and processing system empower 2.1 version . sartorius microbalance and equiptronics branded balance and heating oven was used for the weighing and heating purpose while spinco ultrasonic bath was used for degassing purpose . analytical method development consists of the following steps which can be bound up by the literature survey , previous experience , and chemical nature of the reagents used in the development . on the basis of literature survey , several exploratory runs have been performed but initially proper selectivity and resolution between the drug substance and its impurities were not achieved . after furnishing more importance to the literature , it was concluded that since one impurity specifically 2 - ( 1 - ethyl - methyl ) pentanoic acid is a structural isomer of the drug component ( valproic acid ) , the 5 mm ammonium dihydrogen orthophosphate with ph = 3.0 has given the maximum resolution with acetonitrile as organic component at isocratic elution , 55 : 45 , v / v . most suitable column chemistry was bridge ethyl hybrid ( beh ) c18 among the column chemistry available with us . the resolution between the 2 - ( 1 - ethyl - methyl ) pentanoic acid and the valproate salt was not achieved by the other columns . the standard solution was screened over 190 nm to 400 nm using the advantage of photodiode array detector . on the basis of peak absorption maxima and peak purity index , the 215 nm was decided as the detection wavelength which has provided the maximum chromatographic compatibility to the method . the mobile phase consists of acetonitrile : 5 mm ammonium dihydrogen orthophosphate ( ph = 3.0 ) ( 45 : 55 ) was prepared by dissolving 575 milligram of ammonium dihydrogen orthophosphate for hplc in 1000 ml ultrapure ( hplc grade ) water ; then the ph of the buffer solution was adjusted up to 3.0 using 0.1 % orthophosphoric acid solution . this was further mixed with acetonitrile by mentioned ratio and filtered through 0.22 n filter followed by degassing in ultrasonic bath for 20 min . magnesium valproate and its related impurities working standard solution containing 200 g / ml were prepared in a 100 ml volumetric flask by dissolving 20.0 mg each in 25 ml acetonitrile : water ( 50 : 50 ) and then diluting to volume with the same diluent . further this was filtered through 0.22 n filter followed by degassing in ultrasonic bath for 20 min . magnesium valproate and its related impurities sample ( different batch ) solution containing 200 g / ml were prepared in a 100 ml volumetric flask by dissolving 20 mg each in 25 ml acetonitrile : water ( 50 : 50 ) and then diluting to volume with the same diluent . commercially , magnesium valproate is available in 200 mg , 300 mg , and 500 mg pharmaceutical dosage form . average weight of the tablet was found by weighing 20 tablets and then it was dissolved and diluted to achieve the 200 g / ml concentration . further this was filtered through 0.22 n filter followed by degassing in ultrasonic bath for 20 min . the chromatogram of sample solution and commercial is shown in figures 2 and 3 , respectively . with reference to the method development , chromatographic parameters used for method validation experiments are given in table 1 . method for the determination of magnesium valproate and its related impurities in bulk drug is further validated as per ich q2 ( r1 ) guideline . validation of analytical method was performed using magnesium valproate and its process related impurities working standard and sample batch drug substance . the accuracy experiment was performed by recovery study at three levels , 150 % , 100 % , and 50 % , of the standard concentration . the working standard of magnesium valproate and its related impurities were added to the samples and the recovery was calculated which was between 98 and 102 % ; these were well within the acceptance criteria . six different preparations of the same magnesium valproate and its related impurities sample , each 0.20 mg / ml , were analyzed in triplicate on the same day . the % rsd values obtained for the peak areas of magnesium valproate , valeronitrile , pentanoic acid , 2 - ethyl pentanoic acid , and 2 - ( 1 - methyl , ethyl ) pentanoic acid were not more than 2.0 . the intermediate precision study was performed using another acquity beh c18 column ( 100 mm 2.1 mm i.d . the linearity of the method was evaluated by analyzing eight solutions in the concentration ranges 50350 g / ml for each solution of magnesium valproate and its related impurities . the peak areas obtained from different concentrations of the drugs were used to calculate linear regression equations . these were y = 10.15 x 4.714 , y = 10.06 x + 21 , y = 10.12 x + 5.285 , and y = 10.37 x 21.85 with correlation coefficients of r = 0.999 , r = 0.998 , r = 0.999 , r = 0.997 , and r = 0.998 for pentanoic acid , 2 - ethyl pentanoic acid , 2 - ( 1 - methyl , ethyl ) pentanoic acid , valeronitrile , and magnesium valproate , respectively . the high values of the correlation coefficients were indicative of linear relationships between analyte concentration and peak area . the limits of detection ( lod ) and quantification ( loq ) were established by evaluating the minimum level at which the analytes could be readily detected and quantified with accuracy , respectively . the lod and loq for each component were 1.0 g / ml and 2.0 g / ml . the signal to noise ratio was more than 3 and 10 for lod and loq , respectively . the selectivity of the method was evaluated by injecting blank matrix , each individual impurity , magnesium valproate standard solution , and spiked solution to check the interference of the diluent as well as the standard solution on each other . the method was proved as highly selective that there was no interference on any component to others . the separation factor ( ) was investigated for all the impurities , which found 0.33 , 0.64 , 0.88 , and 0.90 for pentanoic acid , 2 - ethyl pentanoic acid , 2 - ( 1 - methyl , ethyl ) pentanoic acid , and valeronitrile , respectively . the parameters examined were the amount of acetonitrile in mobile phase , the ph of the ammonium dihydrogen orthophosphate solution , and the amount of ammonium dihydrogen orthophosphate solution in the mobile phase . no such impact of the small changes on the above parameters was observed which suggest that the method is highly robust . the robustness study indicated that mainly the ph of the ammonium dihydrogen orthophosphate solution should be monitored carefully to ensure the best separation as this has a significant effect on the separation . the method is found to be selective , precise , sensitive , and linear , which is also proved from the summary of method validation ( table 2 ) . the method can be used for the determination of magnesium valproate and the identification of the impurities present in the pharmaceutical dosage form .\noutput:\n" }, { "from": "agent", "value": "a selective ultraperformance liquid chromatographic ( uplc ) method for the determination of magnesium valproate and its process related impurities has been developed . the method includes reversed - phase acquity beh c18 column with 100 mm 2.1 mm i.d . and 1.7 particle size . the mobile phase consists of acetonitrile and 5 mm ammonium dihydrogen orthophosphate with ph = 3.0 at 45 : 55 isocratic elution . the flow rate was set at 0.3 ml / min and uv detection was performed at 215 nm . a system suitability test ( sst ) was developed to govern the quality of the separation . the developed method has been validated further with respect to linearity , accuracy , precision , selectivity , lod , loq , and robustness . different batches of samples were examined using this method ; the method proved to be successful when applied to analyze a marketed magnesium valproate formulation ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the primary type is caused by the breakdown of endogenous lipids and the secondary type by injection of exogenous foreign bodies . foreign materials , including silicone , paraffin , mineral oil , metallic mercury , petroleum jelly , vaseline , and cod liver oil have been used to provide an improvement in penile shaft contour and dimensions . arthaud et al . , reported the first case of liquid silicone injected to the penis in 1973 , on one subject who had an injection of silicone from a nonprofessional person . liquid injectable silicone for penile augmentation may have debilitating effects , requiring surgical intervention to correct complications . although sonography represents the primary modality for cross - sectional imaging of the penis , magnetic resonance imaging ( mri ) may provide important diagnostic information in the investigation of penile pathology , especially in cases of inconclusive or nondiagnostic sonographic findings . recently , functional mri , including diffusion - weighted imaging ( dwi ) , magnetization transfer imaging ( mti ) , and dynamic contrast - enhanced ( dce ) mri have been used in the interpretation of scrotal diseases . to our knowledge , no reports regarding these techniques in the evaluation of penile diseases exist in the english literature . herein , we present the mri findings of a silicone - induced penile lipogranuloma . a multiparametric mri protocol was used , including dwi , mti , and dce - mri . a 52 - year - old man was referred to the urology department with significant enlargement of the penis and sexual dysfunction of 1 - year duration . the patient reported a history of subcutaneous injection of liquid silicone in the penis by a nonmedical practitioner , 10 years ago . clinical examination revealed large , painless enlargement of the penile shaft due to the presence of a hard mass invading the skin and the subcutaneous tissues , but not the corpora cavernosae . mri examination was done on a 1.5 - t system , with the penis in the flaccid state . the mr protocol included axial spin - echo t1 - weighted sequences , fast spin - echo t2 - weighted sequences in the three orthogonal planes and transverse dw sequences with b - values of 0 and 900 s / mm . mti was followed in the same plane . magnetization transfer ratio ( mtr ) was calculated from the following equation : where , sim and sio refer to signal intensities with and without the saturation pulse , respectively . after a rapid injection of gadopentetate dimeglumine , sagittal dce subtraction mris were also obtained . a heterogeneous , ill - defined mass involving the subcutaneous tissues around the penis and extending into the intertesticular and retrotesticular region were detected [ figure 1 ] . the lesion was asymmetrically y - shaped with the arms of y around corpora carvenosae , slightly hyperintense , and extremely hypointense on t1 - and t2 - weighted images [ figure 1a ] , respectively when compared to the penile shaft . the mean adc was 1.5310 mm / s [ figure 1b ] , similar to that of corpora carvenosae and suggestive of benignity . mtis showed the very low signal intensity of the mass , with a mean mtr of 67 % , suggestive of the presence of macromolecules [ figure 1c and d ] . on dynamic imaging , the lesion enhanced strongly and heterogeneously , with an initial upstroke , followed by gradual increase of enhancement in late postcontrast phase [ figure 1e ] . both the corpora cavernosae and the corpus spongiosum were normal , with intact tunica albuginea . based on mri findings and the clinical history , the diagnosis of silicone - induced penile lipogranuloma was strongly suggested , and the patient was referred for surgical excision of the lesion . 52 - year - old man with silicone - induced penile sclerosing lipogranuloma . ( a ) sagittal t2 - weighted image of the penis demonstrates heterogeneous lesion , with ill - defined margins surrounding the penis . the mass ( arrowheads ) was mainly of low signal intensity on t2 - weighted images , a finding suggestive of the presence of fibrous tissue . ( b ) transverse apparent diffusion coefficient map ( b = 900 mm / s ) shows heterogeneous mass ( arrow ) surrounding the penile shaft . the lesion appears mainly isointense when compared to the normal corpora cavernosa ( long arrow ) . the apparent diffusion coefficient value of the mass was 1.5310 mm / s ( right corpus cavernosum : 1.4910 mm / s ; left corpus cavernosum : 1.6010 mm / s ) . transverse three - dimensional gradient - echo images acquired ( c ) without and ( d ) with the application of the magnetization transfers pulse . the magnetization transfer signal of the mass lesion ( arrowhead ) was qualitatively lower than that of the corpora cavernosa ( arrow ) . ( e ) time - signal intensity curve of the lesion shows an initial upstroke after which the signal intensity gradually increases in the late contrast - enhanced phase . during surgerythe lesion was solid and white , invading the skin , the subcutaneous tissues , and the dartos muscle of the penis . histopathological examination demonstrated vacuoles of variable size corresponding to exogeneous substance , embedded in collageneous stroma . the patient had an uneventful recovery and was advised to return for follow - up 2 months after surgery . histopathologic evaluation of the excised tissue reveals vacuoles of variable size in the dermis corresponding to exogeneous substance . multinucleated giant cells and abundant fibrosis is seen around the vacuoles ( hematoxylin and eosin stain , magnification 20 ) . penile sclerosing lipogranuloma is a granulomatous reaction that occurs after injury of the adipose tissue . the secondary type of the disease is caused by foreign body injections directly into the penis , such as silicone , paraffin oil , paraffin balm , and mineral oils . secondary penile sclerosing lipogranuloma usually requires an aggressive treatment including partial or total excision of granulomas , with or without reconstructive skin flaps depending on the extent of excision . an imaging technique accurately characterizing and assessing the extent of the disease would be valuable in the appropriate preoperative planning of these patients . mri is now increasingly used as either a problem - solving tool in cases of indeterminate sonographic findings or as a primary imaging modality in the evaluation of penile diseases . specifically , mri has been proved useful in the differentiation between benign and malignant penile lesions and in defining the extent of inflammatory processes and traumatic injuries . it is also considered the most accurate imaging technique in the assessment of primary penile carcinomas . motoori et al . , described the mri findings of a primary scrlerosing lipogranuloma of the male genitalia in a 55 - year - old man . the lesion was symmetrically y - shaped , with the arms of the y surrounding the penile shaft . the mass showed similar and moderately high signal intensity when compared to muscles on t1 - and t2 - weighted images , respectively , with irregular enhancement after gadolinium administration . small areas within the lesion , hyperintense on t2 - weighted sequences , without contrast enhancement , suggested the presence of cystic or necrotic parts . the mass demonstrated an ill - defined symmetrical y - shape , situated just beneath the corpus spongiosum with the arms of the y around the penile shaft . the lesion was mainly isointense on t1 - weighted images , strongly enhancing , with low signal intensity on t2 - weighted images , the latter related to the presence of fibrous tissue . an asymmetrically y - shaped mass surrounding the carvenosal bodies and extending into the scrotum was revealed in our patient . the hypointensity of the mass on t2 - weighted sequences was suggestive of the presence of fibrous tissue , as subsequently proved on pathology and it is considered an important diagnostic feature in differentiating this entity from malignancy . lesion detection and characterization on dwi is mainly dependent on the extent of tissue cellularity , and increased cellularity is associated with restricted diffusion and reduced adc . the adc values of malignancies are usually lower than those of benign lesions or normal tissues . in this case , no areas of restricted diffusion were identified within the mass , and the adc was similar to that of normal corpora cavernosae , findings strongly suggestive of benignity . mti sequences offer a different image contrast compared to t1 - and t2 - weighted images . in conventional mris , tissue contrast depends mainly on the presence of free protons , whereas , on mtis , the signal is determined by the restricted macromolecular protons . the mt phenomenon is quantified by the mtr . tissues containing macromolecules , a classical example is fibrous tissue , transfer magnetization more efficiently detected as hypointense on mtis , with high mtr , as in this patient . dce - mri evaluates the kinetics of the distribution of the paramagnetic contrast medium in the micro - vessels and the interstitial spaces of the tissues used . malignancies usually present with the rapid uptake of the contrast medium , followed by washout in the delayed phase , whereas benign lesions often enhance strongly and rapidly , followed by either a plateau or gradual increase of enhancement in the late post - contrast phase . although , there are no reports on the dce - mri characteristics of penile lesions in the english literature , penile lipogranuloma in this case enhanced intensely , followed by a gradual increase of enhancement in the late post - contrast phase , findings that could suggest the benign nature of the lesion . mri examination using both morphologic and functional data provided valuable information in the preoperative planning in our case , by estimating the precise extent of the mass and helping in the characterization of the benign nature of disease .\noutput:\n" }, { "from": "agent", "value": "sclerosing lipogranuloma is a rare benign disease , representing a peculiar granulomatous reaction of fatty tissue . the majority of cases are secondary to injection of exogenous foreign bodies , such as silicone , paraffin , mineral , or vegetable oils . to the best of our knowledge , we present the first case of a silicone - induced penile lipogranuloma in a 52 - year - old man evaluated with a multiparametric magnetic resonance imaging ( mri ) protocol , including diffusion - weighted imaging , magnetization transfer imaging , and dynamic contrast - enhanced mri . mri of the penis by combining both conventional and functional information represents an important imaging tool in the preoperative workup of silicone - induced penile lipogranuloma ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we examined 44 patients with stenosis of the cervical spine , 26 were male and 18 were female ( mean age , 49 years ; range , 20 - 87 years ) . the causative pathologies are detailed in table 1 . to investigate the normal pattern of csf dynamics in the cervical spine , ten healthy volunteers , all male ( mean age , 26 years ; range , 20 - 57 years ) , were included . the degree of stenosis in the cervical spinal canal was rated as low - , intermediate - , or high - grade . low - grade stenosis is defined as occurring where there is no evidence of effacement of the csf space , and csf signal intensity between the dural sac and the spinal cord is seen on t2 - weighted images . stenosis is defined as intermediate - grade where there is effacement of the dural sac on the spinal cord , but with no evidence of compressive myelopathy demomstrated by t2 - weighted imaging . high - grade stenosis involves effacement of the dural sac on the spinal cord , together with evidence of compressive myelopathy revealed by t2 - weighted imaging . the study involved the use of a 1.5 - t whole - body imaging system ( siemens medical systems , erlangen , germany ) with a cp - spine - array coil . to produce a grid or stripe pattern in the object , a tagging rf pulse was applied immediately after the trigger pulse , and this pattern was followed by a series of fast gradient - echo sequences . the number of gradient echo measurements was adjusted according to the number of phases , as is the case with a standard cine - type technique . without any additional saturation pulses , the time between the application of the tagging rf pulse and the first gradient echo was as short as 2 msec . the application of subsequent gradient echoes was defined by the pulse repetition time ( tr ) , as shown in fig . ecg - triggered multi - phase images were acquired using the following parameters : tr / te / td / flip angle , 42 msec / 7.2 msec / 0 - 630 msec / 20 ; matrix , 128256 ; slice thickness , 6 mm ; fov , 250 mm ; saturation thickness , 10 mm ( stripe thickness was expressed as 2 mm ) . sixteen phase - images at the same slice between every r - r wave of the ecg , as well as sagittal and coronal spamm images , were obtained . this sagittal image was compared with the pathologic status of a spin - echo t2 - weighted sagittal image , and the coronal spamm image was used to observe csf flow through the lateral canal in the dural sac . in the spamm stripe , a continuous straight band represents no flow movement , while wave displacement or discontinuity of the band indicates flow movement . in the theory , therefore , low - grade stenosis should show wave displacement or discontinuity , whereas intermediate - and high - grade stenosis should show a continuous straight band . in all stenosis patients and normal volunteers , csf velocity was measured during each diastolic and systolic phase in the upper cervical subarachnoid space anteriorly to the c1 - 2 level , and in low - grade stenosis patients and volunteers , anteriorly to the c4 - 5 level . the reason for selecting the c4 - 5 level for evaluation of csf velocity was that physiologic stenosis is observed in this segment where the thickest cervical cord is present . csf velocity is given by distance over time ( time for the tag to move ) . using the statistics package in the hardware , the extent of bolus displacement was measured manually on the monitor with a magnifying view , and from the trailing edge of the stationary tag to the trailing edge of the flow tag ( fig . thus , csf velocity with consecutive gradient - echo readouts was given by distance of bolus tag divided by tr , which in this study was 42 msec . three radiologists classified the degree of cervical spinal stenosis seen on routine spinal mr imaging as one of three grades , and blindly evaluated the stripe patterns of spamm . the statistical significance of differences in interobserver reliability was analyzed using the cronbach coefficient alpha test ; 0.7 or higher cronbach coefficient alpha is adequate . the confidence level between stripe patterns of spamm and grades of cervical spinal stenosis was checked by a confidence interval of 95 % . using the paired t test , differences in csf velocity determined using the spamm technique were found to be significant for p .05 . in healthy volunteers and patients , three patterns of spamm stripes were demonstrated ( fig . spamm stripes through normal csf spaces in the cervical spine showed harmonious parabolic wave displacement corresponding to the csf flow direction ( fig .4 ) . no healthy volunteers showed flow separation on spamm images . with regard to pathologic status , the classification of grades of stenosis and stripe patterns performed blindly by three radiologists is summarized in table 2 . interobserver reliability regarding classification of grades of stenosis was high ( cronbach coefficient alpha , .996 ) .5 ) , interobserver reliability for displaced or discontinuous stripes in the stenotic segment was high ( cronbach coefficient alpha , .992 ) and the confidence level between stripe patterns of spamm and grades of spinal stenosis was also high ( 95 % confidence interval ) . twelve cases showed wave separation , with double shape during the systolic phase . in intermediate - grade stenosis6 ) , interobserver reliability with regard to the continuous straight band seen in the stenotic segment was high ( cronbach coefficient alpha , .842 ) , but the confidence level was intermediate ( 95 % confidence interval ) . in high - grade stenosis ( n = 11 ) ( fig .7 ) , interobserver reliability with regarding the continuous straight band in the stenotic segment was perfect ( cronbach coefficient alpha 1.0 ) and the confidence level was also high ( 95 % of confidence interval ) . in five cases of severe focally herniated cervical disc , accentuation of the spamm stripe throu - gh the lateral canal was revealed by coronal spamm images . in healthy volunteers , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.800.03 ( 2sd ) and 1.330.03 ( 2sd ) cm / sec , respectively ( table 3 ) . at the c4 - 5 level , mean csf velocities during the diastolic and systolic phases were 0.780.03 ( 2sd ) and 1.850.03 ( 2sd ) cm / sec , respectively . during the systolic phase , csf velocity at the c4 - 5 level was significantly higher than at the c1 - 2 level ( p .05 ) . in the low - grade stenosis , the mean diastolic and systolic csf velocities in the anterior subarachnoid space at the c1 - 2 level were 0.670.04 ( 2sd ) and 1.340.02 ( 2sd ) cm / sec , respectively . at stenotic c4 - 5 level in low - grade stenosis , mean diastolic and systolic csf velocities were 0.680.04 ( 2sd ) and 1.650.05 ( 2sd ) cm / sec , respectively . during the systolic phase , csf velocity at the c4 - 5 level was significantly higher than at the c1 - 2 level ( p .05 ) but the velocity at this level was significantly lower than in healthy volunteers ( p .05 ) . in intermediate - grade cases , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.640.06 ( 2sd ) and 1.190.06 ( 2sd ) cm / sec , respectively . peak systolic velocity was lower than in healthy volunteers , but the difference was not statistically significant ( p .05 ) . in high - grade stenosis , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.490.03 ( 2sd ) and 1.060.11 ( 2sd ) cm / sec , respectively . as compared with healthy volunteers , velocities during both the diastolic and systolic phases were significantly lower ( p .05 ) . in healthy volunteers and patients , three patterns of spamm stripes were demonstrated ( fig . spamm stripes through normal csf spaces in the cervical spine showed harmonious parabolic wave displacement corresponding to the csf flow direction ( fig .4 ) . no healthy volunteers showed flow separation on spamm images . with regard to pathologic status , the classification of grades of stenosis and stripe patterns performed blindly by three radiologists is summarized in table 2 . interobserver reliability regarding classification of grades of stenosis was high ( cronbach coefficient alpha , .996 ) .5 ) , interobserver reliability for displaced or discontinuous stripes in the stenotic segment was high ( cronbach coefficient alpha , .992 ) and the confidence level between stripe patterns of spamm and grades of spinal stenosis was also high ( 95 % confidence interval ) . twelve cases showed wave separation , with double shape during the systolic phase . in intermediate - grade stenosis6 ) , interobserver reliability with regard to the continuous straight band seen in the stenotic segment was high ( cronbach coefficient alpha , .842 ) , but the confidence level was intermediate ( 95 % confidence interval ) . in high - grade stenosis ( n = 11 ) ( fig .7 ) , interobserver reliability with regarding the continuous straight band in the stenotic segment was perfect ( cronbach coefficient alpha 1.0 ) and the confidence level was also high ( 95 % of confidence interval ) . in five cases of severe focally herniated cervical disc , accentuation of the spamm stripe throu - in healthy volunteers , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.800.03 ( 2sd ) and 1.330.03 ( 2sd ) cm / sec , respectively ( table 3 ) . at the c4 - 5 level , mean csf velocities during the diastolic and systolic phases were 0.780.03 ( 2sd ) and 1.850.03 ( 2sd ) cm / sec , respectively . during the systolic phase , csf velocity at the c4 - 5 level was significantly higher than at the c1 - 2 level ( p .05 ) . in the low - grade stenosis , the mean diastolic and systolic csf velocities in the anterior subarachnoid space at the c1 - 2 level were 0.670.04 ( 2sd ) and 1.340.02 ( 2sd ) cm / sec , respectively . at stenotic c4 - 5 level in low - grade stenosis , mean diastolic and systolic csf velocities were 0.680.04 ( 2sd ) and 1.650.05 ( 2sd ) cm / sec , respectively . during the systolic phase , csf velocity at the c4 - 5 level was significantly higher than at the c1 - 2 level ( p .05 ) but the velocity at this level was significantly lower than in healthy volunteers ( p .05 ) . in intermediate - grade cases , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.640.06 ( 2sd ) and 1.190.06 ( 2sd ) cm / sec , respectively . peak systolic velocity was lower than in healthy volunteers , but the difference was not statistically significant ( p .05 ) . in high - grade stenosis , mean csf velocities during the diastolic and systolic phases in the anterior subarachnoid space at the c1 - 2 level were 0.490.03 ( 2sd ) and 1.060.11 ( 2sd ) as compared with healthy volunteers , velocities during both the diastolic and systolic phases were significantly lower ( p .05 ) . since du boulay 's investigations ( 3 , 4 ) , it has been known for certain that oscillating csf pulsation is a response to the transient increase in intracranial blood volume occurring during the cardiac cycle . arterial inflow showed an early systolic peak about 100 msec after the r wave of the ecg , while venous outflow was almost continuous with only a subtle diastolic flow increase in the internal jugular vein ( 12 ) . this leads to a transitory systolic increase in blood volume inside the indistensible skull , which must be compensated for by displacement of csf . it was found that a delay of about 100 - 200 msec occurred between the arterial pulse wave and the downward flow of csf in the cervical spinal canal and the cerebral aqueduct ( 12 ) , and our results showed that there was a delay of about 210 msec between the initial r wave and the downward flow of csf in the cervical spinal canal . thus , a downward flow tag was visualized during the fifth phase , when tr was 42 msec . the oscillatory motion of csf in the spinal canal has been studied by various means . in the literature , csf velocity in the cervical spine is reported to range from 0.8 to 3.1 cm / sec ( 11 , 13 ) . the velocity decreases as the csf descends the spinal axis and changes to 0 - 2.8 cm / sec in the lumbar area ( 5 , 14 ) . in our experience , maximal velocity in the cervical area of healthy volunteers occurs at the c4 - 5 level , and this is probably due to the fact that the spinal cord is at its thickest and the subarachnoid space at its narrowest at this level ( 15 ) . similarly , the pathologic narrowing of csf space can cause jet - like csf propulsion . in the lumbar area , because the spinal cord extended only to the l2 level , leaving a large csf space , velocity decreased . for spinal canal compromise andassociated flow attenuation or arrest , a variable scale of mr signal reduction was anticipated ( 16 ) . according to the author 's classification of cervical spinal stenosis , low - grade stenosis showed greater velocity at the maximal stenotic segment than at the c1 - 2 level , as described in another study ( 16 ) , and it therefore appears that partial canal patency allowed jet - like csf propulsion . our results also showed that low - grade stenosis at the c4 - 5 level involved a jet - like propulsion flow , which can be also be present in healthy volunteers . these increasing velocities at stenotic c4 - 5 level were not statistically different from those found in healthy volunteers . one previous study suggested that low - grade stenosis merely reflected local flow turbulence and was of little diagnostic value for predicting degrees of stenosis ( 16 ) . our results showed that in about half of all low - grade stenosis cases showed wave separation occurred during the systolic phase through the anterior csf space , suggesting a jet - like flow . if there is sufficient space for flow tags in the posterior csf space , the phenomenon of flow separationintermediate - and high - grade stenosis , on the other hand , did not demonstrate this phenomenon . flow separation is , therefore , of some diagnostic value for predicting degrees of stenosis , and helps provide an understanding of the hydrodynamic changes undergone by csf in spinal stenosis . intermediate - grade stenosis , defined as involving effacement of the dural sac on the spinal cord , did not reveal 95 % confidence for hydrodynamic change of spamm stripes . in spite of the effacement between the dural sac and the cord revealed by 1.5 - t mri , the displaced or discontinuous stripes seen in many cases of intermediate - grade stenosis were , therefore , due to the wide range of a dynamic flow , doubtful . one hypothesis is that there was overinterpretation of low - grade stenosis as intermediate - grade . factors that may cause incorrect grading of stenosis include the truncation artifact ( gibbs phenomenon ) , chemical shift , movement by the patient , and csf pulsation artifact ( 17 ) . on spamm , even partial canal patency , which might not be easily depicted on t2 - weighted images , allows csf propulsion to be expressed as subtle displacement or discontinuity of the stripe . high - grade stenosis attenuated csf velocity sufficiently for it to become nearly stagnant . in some of our high - grade stenosis cases , lateral canal accentuation of csf was observed , a finding which may reflect compensatory csf propulsion through the lateral pathway of csf between the lateral border of the cord and the dura . because the transverse diameter of the spinal cord is greater than the anteroposterior diameter ( 15 ) , the lateral canal of the csf space would normaly be a minor pathway of csf flow . to our knowledge , no previous report has described findings relating to csf flow through the lateral canal . we attempted to detect csf flow through this canal using coronal spamm images , and were able to observe accentuated wave displacement through the canal in some high - grade stenosis cases , but not in healthy volunteers or in cases of low - or intermediate - grade stenosis . in cases of high - grade stenosis involving complete blockage of the anterior and posterior subarachnoid space , the lateral canal may be a major pathway . coronal spamm imaging may , therefore , be helpful for differentiating high - grade stenosis from lower grades . in our studyfour cases of low - grade stenosis showed a continuous straight band , a discrepancy which might have resulted from overlapping of the dark signals of spamm stripes with the posterior marginal osteophytes of vertebral bodies , which showed dark signals in one or two segments . two cases of high - grade stenosis showed stripe displacement , mimicking the existence of csf flow , and this might have been influenced by the adjacent flow effect . possible causes of these errors are the partial volume effect , induced by the selection of 6 - mm slice thickness , and the posterolateral directional pathology of spinal stenosis . in this study , low - grade stenosis showed considerable changes in csf hydrodynamics ; these included increased jet - like stream velocity through the canal and flow separation in approximately half of all cases , reflecting oscillation of jet - stream unrelated to flow turbulence . high - grade spinal stenosis with continuous straight bands could be interpreted as involving complete csf blockage , while intermediate - grade , with wave discontinuity or displacement , may show minimal csf canal patency . a continuous straight band indicates severe stenosis , which is a sign of direct attachment between csf and dura , and hence , a definite sign indicating the need for decompressive surgery such as laminectomy . in conclusion , clinical application of the spamm technique for the evaluation of cervical spinal stenosis was susccesful . the technique is effective for the evaluation of csf hydrodynamic changes occurring in cervical spinal stenosis .\noutput:\n" }, { "from": "agent", "value": "objectiveto evaluate the hydrodynamic changes occurring in cerebrospinal fluid ( csf ) flow in cervical spinal stenosis using the spatial modulation of magnetization ( spamm ) technique.materials and methodsusing the spamm technique , 44 patients with cervical spinal stenosis and ten healthy volunteers were investigated . the degree of cervical spinal stenosis was rated as low - , intermediate - , or high - grade . low - grade stenosis was defined as involving no effacement of the subarachnoid space , intermediate - grade as involving effacement of this space , and high - grade as involving effacement of this space , together with compressive myelopathy . the patterns of spamm stripes and csf velocity were evaluated and compared between each type of spinal stenosis and normal spine.resultslow - grade stenosis ( n = 23 ) revealed displacement or discontinuity of stripes , while intermediate - ( n = 10 ) and high - grade ( n = 11 ) showed a continuous straight band at the stenotic segment . among low - grade cases , 12 showed wave separation during the systolic phase . peak systolic csf velocity at c4 - 5 level in these cases was lower than in volunteers ( p < .05 ) , but jet - like csf propulsion was maintained . among intermediate - grade cases , peak systolic velocity at c1 - 2 level was lower than in the volunteer group , but the difference was not significant ( p > .05 ) . in high - grade stenosis , both diastolic and systolic velocities were significantly lower ( p < .05 ) . conclusionvarious hydrodynamic changes occurring in csf flow in cervical spinal stenosis were demonstrated by the spamm technique , and this may be a useful method for evaluating csf hydrodynamic change in cervical spinal stenosis ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: parkinson 's disease ( pd ) is a progressive , complex disorder characterized by motor symptoms ( bradykinesia , rigidity , resting tremor , and postural instability ) as well as a wide range of nonmotor symptoms ( nms ) that contribute to significant morbidity and disability . it is important to identify those nms that most influence the patient 's life , since they may not be evident during the clinical examination . nms like depression , anxiety , cognitive decline , pain , fatigue , insomnia , and autonomic dysfunction ( constipation , urinary symptoms ) are significant factors that diminish health - related quality of life ( hrqol ) of individuals with pd . while common , they are still often underrecognized in clinical practice because patients fail to spontaneously mention them , and healthcare professionals also fail to systematically ask about them . some symptoms , for example , olfactory deficit , constipation , rapid - eye movement sleep behavior disorder , and depression , can even precede the appearance of motor symptoms by many years . most of the pd - associated nms are believed to be caused by the nondopaminergic systems , in accordance with the hypothesis that other neurotransmitters including serotoninergic , noradrenergic , and cholinergic transmission are involved . however , in a recent study on advanced pd subjects , storch and coworkers showed that seven out of ten selected nms ( with the exception of dysphagia , excessive sweating , and bladder urgency ) fluctuated in conjunction with motor symptom fluctuations . moreover , they were also more frequent and more severe in off than in the on state . this evidence indicates that any optimization of dopaminergic therapies must also address the management of nms . in light of the above facts , our study aimed to determine the impact of nms on hrqol in a cohort of central european pd patients from the slovak republic who were already on dopaminergic medications . we hypothesized that the involvement of individual nms domains would differ depending on the disease stage . therefore , special emphasis was placed on a comparison of early - stage and advanced - staged pd patients . one hundred consecutive patients with idiopathic pd diagnosed according to the uk parkinson 's disease society brain bank criteria were recruited from two specialized movement disorder units of tertiary centers . all subjects gave their informed written consent in accordance with the declaration of helsinki , and the local ethics committee approved the study protocol . patients with mild cognitive impairment were included if their informed written consent could be obtained and they were able to complete clinimetric questionnaires alone or with the help of their caregiver . all patients had been on dopaminergic therapy with levodopa ( plus dopa decarboxylase inhibitor ) and / or dopamine agonists for at least 3 months . untreated subjects or those on advanced therapies like deep brain stimulation , subcutaneous apomorphine pump , or intrajejunal levodopa infusion pump were not included . for analysisthe patients were divided into early - stage ( es ) and advanced - stage ( as ) groups on the basis of the modified hoehn and yahr score ( h & y ) , the cut - off of 2.5 , and a history of late complications of levodopa therapy . six patients were classified in h & y1 , 1 in h & y1 .5 , 31 in h & y2 , and 9 in h & y2 .5 ( es subjects ) . forty - five people were in h & y stage 3 , 7 in h & y4 , and 1 in h & y5 ( as patients ) . dopaminergic therapy load was expressed in terms of levodopa equivalent daily dose ( ledd ) . each person was in the state in which parkinson motor symptoms were best controlled during assessment . validated slovak translations of the following screening and diagnostic instruments were applied : the parkinson 's disease questionnaire with eight dimensions ( pdq - 8 ) , health - related quality of life measure , a summary index ( pdq - 8 si ) which was used for statistical analysis , the nonmotor symptoms screening questionnaire ( nmsquest ) , a 30 - item tool , which records the presence or absence of nonmotor symptoms , the nonmotor symptom assessment scale for parkinson 's disease ( nmss ) , a 30 - item scale for assessing nms , which covers nine dimensions : cardiovascular , sleep / fatigue , mood / apathy , perceptual problems , attention / memory , gastrointestinal , urinary , sexual function , and miscellaneous . the parkinson 's disease questionnaire with eight dimensions ( pdq - 8 ) , health - related quality of life measure , a summary index ( pdq - 8 si ) which was used for statistical analysis , the nonmotor symptoms screening questionnaire ( nmsquest ) , a 30 - item tool , which records the presence or absence of nonmotor symptoms , the nonmotor symptom assessment scale for parkinson 's disease ( nmss ) , a 30 - item scale for assessing nms , which covers nine dimensions : cardiovascular , sleep / fatigue , mood / apathy , perceptual problems , attention / memory , gastrointestinal , urinary , sexual function , and miscellaneous . questionnaires pdq - 8 and nmsquest were completed by patients ( with the aid of caregivers if necessary ) while waiting to be seen by a neurologist . clinical and demographic variables of both groups of pd patients were compared by student 's t - test ( p 0.05 ) . the kolmogorov - smirnov test showed that not all data were normally distributed , so spearman 's rank correlation coefficient ( rho ) was used to evaluate the association between pdq - 8 and demographic and clinical variables , nmsquest score , nmss total score , and nine different nmss domains . the strength of the association for correlation coefficients was interpreted as follows : 0.19 , negligible ; 0.20 to 0.39 , weak ; 0.40 to 0.59 , moderate ; 0.60 to 0.79 , strong ; and 0.80 , very strong . compared to es patients , as subjects had significantly higher scores on the pdq - 8 , nms - quest ( number of nms ) , and nmss ( table 1 ) . the average declared number of nms in all 100 patients was 11.3 ; the average number in es was 9.6 , and in as 12.8 . table 2 presents the correlations found between quality of life measure pdq - 8 and selected variables of interest . the evaluation of all 100 patients showed a weak correlation with the duration of pd and nmss cardiovascular aspects , nmss sleep / fatigue , nmss / perceptual problems , nmss / gastrointestinal aspects , and nmss / miscellaneous . the h & y score , nmsquest , nmss total , nmss mood / apathy , and nmss attention / memory domain revealed correlations , which were moderate to strong . the as group had a pdq - 8 score that correlated moderately with nmsquest , nmss total , and nmss sleep / fatigue scores . weak correlations were found for nmss cardiovascular , nmss mood / apathy , and nmss attention / memory domains . although nms greatly influence the hrqol of pd patients , more than 50 % of existing nms are not identified in clinical practice . the prevalence of overall nms in our cohort of 100 pd subjects on dopaminergic drugs was 11/30 . according to the nmsquest ( evaluation of prevalence ) and nmss ( frequency severity ) the nonmotor symptoms were significantly associated with poor hrqol across the entire clinical spectrum of pd . this finding agrees with the proposal to consider the frequency and severity of nonmotor symptoms as a whole to be the most important predictor of hrqol in pd . surprisingly , separate evaluation of nmss domain correlation profiles for early - stage and advanced - stage groups did not reveal any fundamental differences ; however , the degree of the association with hrqol differed . the neuropsychiatric domains attention / memory and mood / apathy correlated moderately to strongly with hrqol in the es group , while hrqol was moderately related to the sleep / fatigue domain in the as group . other weak but still significantly correlating domains were sleep / fatigue in es and cardiovascular aspects , attention / memory , and mood / apathy in as . our data are thus in line with previous studies reporting that fatigue , sleep disturbances , apathy , and mood are independent determinants of hrqol . as our subjects had been optimallytuned up with dopaminergic therapy ( according to the clinicians ' impressions ) and fluctuating patients were assessed in their optimal on state , we can assume that nondopaminergic lesions influenced their hrqol the most . an important limitation of our study is that the most advanced phases of disease were underrepresented . other drawbacks are the absence of severity measures for motor symptoms , like updrs motor score , to determine the impact of motor system involvement , and the fact that special attention was not given to nondopaminergic add - on therapies , for example , antidepressants , hypnotics , cognitives , and laxatives . in conclusion , our data confirm that nms are very common and significantly influence hrqol even in pd patients on dopaminergic therapy . these observations indicate that systematic , active screening for nms and above all therapeutic strategies for neuropsychiatric disorders ( mood , cognition , sleep , and fatigue ) are urgently required both at the initial diagnosis of pd and across the entire disease course . further studies are needed to investigate how to improve the hrqol of pd patients and relieve their nms .\noutput:\n" }, { "from": "agent", "value": "to determine the impact of nonmotor symptoms ( nms ) on health - related quality of life ( hrqol ) we examined 100 parkinson 's disease ( pd ) patients on dopaminergic medications . an early - stage ( es ) and an advanced - stage ( as ) groups were formed . hrqol was established by the questionnaire pdq - 8 , number of nms by nmsquest , and severity and frequency of nms by the assessment scale nmss . the total nms averaged 11.3 ( es = 9.6 , as = 12.8 ) . the nmss domain correlation profiles for es and as did not fundamentally differ ; however , the domains attention / memory and mood / apathy correlated moderately to strongly with hrqol in es , while the sleep / fatigue domain correlated moderately with hrqol in as . weakly correlating domains were sleep / fatigue in es and cardiovascular , attention / memory , and mood / apathy domains in as . in view of these findings we strongly recommend systematic , active screening and therapy for neuropsychiatric disorders ( mood , cognitive and sleep disorders , and fatigue ) at the initial diagnosis and throughout the entire course of pd ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: arsenic is the most ubiquitous toxic substance in the environment as the result of geochemical and anthropogenic exposure . in humans , arsenic is associated with a broad range of acute and chronic toxic effects that increase the lifetime risk of cancer and diabetes as well as cardiovascular and neurological diseases . consequently , arsenic rates first on the united states center for disease control and prevention ( cdc ) and environmental protection agency s ( epa ) priority list of hazardous substances ( http://www.atsdr.cdc.gov/spl/ ) . in humans , s - adenosylmethionine as ( iii ) methyltransferase ( has3mt , ec 2.1.1.137 ) catalyzes transfer of methyl groups from sam to as ( iii ) , producing mas , dmas , and traces of tmas . human as3mt is primarily a liver enzyme that is a member of a large superfamily of methyltransferases that are involved in many physiological functions . in humans , biotransformation of small molecules into carcinogens is common , and arsenic biomethylation is associated with arsenic - related cancers by conversion of inorganic arsenic ( as ( iii ) ) into carcinogenic trivalent mas ( iii ) and dmas ( iii ) . to dateone hypothesis proposed by challenger is that the enzyme catalyzes a series of alternating oxidative methylations and reductions , using s - adenosylmethionine as the methyl donor to generate the pentavalent products methylarsenate ( mas ( v ) , dimethylarsenate ( dmas ( v ) ) and a lesser amount of trimethylarsine oxide ( tmas ( v ) o ) . the trivalent species mas ( iii ) , dmas ( iii ) , and tmas ( iii ) are intermediates but not products . most consistent with this hypothesis is that humans primarily excrete dmas ( v ) and to a lesser extent mas ( v ) . however , with careful handling , trivalent methylated arsenicals can be detected in urine . more recently , hayakawa and co - workers proposed an alternate pathway in which the preferred substrates of the methyltransferase are the glutathione ( gsh ) conjugates as ( gs ) 3 and mas ( gs ) 2 , and the products are the trivalent conjugates mas ( gs ) 2 and dmas ( gs ) . in this pathway , there is no change in the oxidation state of arsenic , which remains trivalent throughout the catalytic cycle . the conjugates dissociate to unstable mas ( iii ) and dmas ( iii ) , which rapidly oxidize nonenzymatically in air to mas ( v ) and dmas ( v ) , the primary observed urinary species . knowledge of the enzymatic mechanism of as3mt is critical for understanding its parallel roles in arsenic detoxification and carcinogenesis . as3mt was first purified from rat liver cytosol by thomas and co - workers , and the rat and human genes were subsequently cloned . the enzyme methylates inorganic as ( iii ) using sam as methyl donor and a variety of reductants , both artificial and natural , including thioredoxin ( trx ) ( with an nadph and thioredoxin reductase ( tr ) regenerating system ) . however , their protein had such extremely low activity that an excess of enzyme ( 3 m ) over substrate ( 1 m as ( iii ) ) was required for extended periods ( 2 h ) to observe methylation . with an excess of enzyme , there is at most a single turnover and not real measurement of catalysis . ding et al . this enzyme was capable of slowly producing both mas ( iii ) and dmas ( iii ) , with either trx or the artificial reductant tris ( 2 - carboxyethyl ) phosphine ( tcep ) supplying reducing potential . in vitro , this purified has3mt methylates as ( iii ) primarily to dmas ( v ) , but , like the other has3mt expressed from a cdna clone , its activity is low . equimolar enzyme and as ( iii ) ( each at 1 m ) for 2 h was required to transform as ( iii ) to dmas ( v ) , so this may also represent only a single turn over and not sustained catalysis . the in vitro properties of human as3mt have not been systematically analyzed under catalytic conditions but only in assays with stoichiometric enzyme . we also expressed a cdna clone of human as3mt and purified has3mt by heterologous expression in escherichia coli . ( 17 ) however , this preparation of recombinant enzyme was no more active than those of other laboratories . to produce a highly active form of human as3mt functional in catalytic concentrations and to improve expression , the has3mt gene was chemically synthesized with codon optimization for e. coli . codon optimization does not alter the amino acid sequence of the protein but generally improves translation , protein folding , and activity . the synthetic enzyme exhibited high activity in catalytic concentrations . in this study , we examined the catalytic properties of the synthetic enzyme . binding of arsenicals to a single - tryptophan derivative of has3mt was estimated from the quenching of intrinsic protein fluorescence , and the enzyme appears to bind as ( gs ) 3 preferentially over inorganic as ( iii ) . mas ( iii ) was the primary product observed within the first few minutes of catalysis but remained mostly enzyme - bound until it was methylated a second time . these results are consistent with the pathway proposed by hayakawa and co - workers and are inconsistent with the challenger pathway . the involvement of the four conserved cysteine residues , cys32 , cys61 , cys156 , and cys206 , was examined by site - directed mutagenesis . substitution of any of the four resulted in loss of ability to methylate as ( iii ) , but both the c32s and c61s derivates could still methylate mas ( iii ) . these results suggest that only cys156 and cys206 are required for all steps in the methylation pathway and that cys32 and cys61 play a different role in the catalysis . a homology model of has3mt based on the crystal structure of a thermophilic orthologue indicates that cys156 and cys206 form the binding site for as ( iii ) and mas ( iii ) , whereas cys32 and cys61 approach each other closely enough to form a disulfide bond . we propose that this disulfide bond forms during the catalytic cycle and that a role of trx is to reduce the disulfide and regenerate the active form of as3mt . unless otherwise stated , all reagents were purchased from sigma - aldrich co. llc ( st . louis , mo ) . mas ( v ) was reduced to mas ( iii ) as described . for dna manipulation , e. coli top10 ( fmcra ( mrr - hsdrms - mcrbc ) 80laczm15lacx74 reca1 arad139 ( araa - leu ) 7697 galu galk rpsl enda1 nupg ) was employed through out . a has3mt gene corresponding to the sequence of the cdna clone , which lacks the last nine residues of the has3mt sequence , was chemically synthesized with 5 ncoi and 3 sali sites and with codon optimization for expression in e. coli and subcloned into the ecorv site of puc57 - kan ( genscript , nj , usa ) . the synthetic has3mt gene was cloned as an ncoi / sali digest from puc57 - kan - has3mt into expression vector pet41a ( + ) that produces a fusion with the schistosoma japonicum glutathione s - transferase ( gst ) gene at the 5 end and eight histidine residues at the 3 end . to produce the natural protein , the 1.1 kb fragment was amplified by pcr using forward primer 5 - ccagccatggctgcacttcgtgacgctgaga - 3 ( ncoi site underlined ) and reverse primer 5 - cctagtcgactccagcagcatcagggacacatc - 3 ( sali site underlined ) . the pcr product was cloned into pbad - myc / his - a as an ncoi / sali digest , generating plasmid pbad - has3mt in which the gene was fused with a six - histidine tag at the 3 end . all sequences were verified by sequencing the entire gene by sequetech , ca , usa . mutations in the as3mtwere introduced by site - directed mutagenesis using a quikchange mutagenesis kit ( stratagene , la jolla , ca ) . the codons for the conserved cys32 , cys61 , cys156 , and cys206 and nonconserved cys72 , cys85 , and cys250 residues were changed to serine codons , generating seven different single - cysteine mutants of the synthetic has3mt . the double c32s / c61s mutant was generated by mutating codon 32 in the c61s derivative to a serine codon . wild - type synthetic as3mt and its mutants were expressed in e. coli bl21 ( de3 ) . cells bearing plasmid pet41a - has3mt were cultured at 37 c in 1 l of luria broth medium consisting of 10 g of tryptone , 5 g of yeast extract , and 10 g of nacl per liter containing 50 g / ml kanamycin to mid log phase ( a600 nm 0.50.6 ) before induction with 0.3 mm isopropyl - d -1-thiogalactopyranoside ( iptg ) for 3 h. the induced culture was centrifuged at 5000 rpm at 4 c for 15 min , suspended in 20 ml of buffer a consisting of 50 mm nah2po4 , ph 8.0 , containing 0.3 m nacl and 1 mm tcep to which 10 mm imidazole was added . the cells were lysed using a french press in the presence of diisopropyl fluorophosphate and centrifuged at 35000 rpm for 1 h. the supernatant was loaded ( 0.7 ml / min ) onto a 5 ml ni - nta agarose column , pre - equilibrated with 5 column volumes of buffer a. the column was washed ( 1 ml / min ) with 10 column volumes of buffer a containing 20 mm imidazole , has3mt was eluted ( 0.7 ml / min ) with 8 column volumes of buffer a containing 0.25 m imidazole . imidazole was removed , and the protein was concentrated to 1 ml by centrifugation , washing three times with 4 ml of buffer a containing no imidazole , with amicon ultra centrifugal filters with 30k membrane ( millipore , billerica , ma ) . glycerol was added to 20 % ( v / v ) , and the protein was stored in 25 l aliquots at 80 c until use . the cells were cultured at 37 c in 1 l of luria broth medium containing 100 g / ml ampicillin to mid log phase ( a600 nm 0.50.6 ) before induction with 0.2 % ( w / v ) l - arabinose for 3 h. the natural has3mt was purified as described above . trx and tr were purified by ni - nta chromatography as described above from e. coli bl21 ( de3 ) carrying either pet14b - trxa or pet14b - trxb ( kindly provided by j. messens of vib - vrije universiteit , brussels , belgium ) . methylation of as ( iii ) and mas ( iii ) was assayed both in e. coli expressing as3mt genes and by purified proteins . individual colonies of e. coli strains bl21 ( de3 ) or top10 bearing the appropriate plasmids were inoculated into 2 ml of luria broth medium supplemented with the appropriate antibiotics and incubated at 37 c overnight . late exponential phase cells were diluted 200-fold into 2 ml of luria broth medium containing 50 g / ml kanamycin , 0.3 mm iptg , and 20 m sodium arsenite . after 12 h at 37 c , the cells were removed by centrifugation , and the supernatant solution was immediately passed through a 3 kda cutoff amicon ultrafilter ( millipore , billerica , ma ) . the filtrate was speciated by high - pressure liquid chromatography ( hplc ) ( perkinelmer series 2000 ) using a c18 reversed - phase column eluted with a mobile phase consisting of 3 mm malonic acid , 5 mm tetrabutylammonium hydroxide , and 5 % ( v / v ) methanol ( ph 5.9 ) with a flow rate of 1 ml / min , and arsenic content was determined by inductively coupled plasma mass spectrometry ( icp - ms ) using an elan drc - e spectrometer ( perkinelmer , waltham , ma ) . methylation activity of purified as3mts was assayed at 37 c in buffer b consisting of 50 mm nah2po4 , ph 8.0 , containing 0.3 m nacl . unless otherwise noted , the assays contained 5 mm gsh , 1 mm sam , 10 m trx , 3 m tr , and 0.3 mm nadph , and the reactions were terminated by adding 10 % ( v / v ) h2o2 to oxidize all arsenic species . denatured protein was removed by centrifugation using a 3 kda cutoff amicon ultrafilter . the filtrate was speciated by hplc - icp - ms . where noted , h2o2 was not added to allow for determination of trivalent arsenicals . without oxidation , the majority of the arsenic at early times was found to be bound to the enzyme . to determine the nature of as3mt - bound arsenicals , purified synthetic has3mt ( 5 m ) was incubated at 37 c with 20 m as ( iii ) as described above for 10 min . a portion of the assay mixture was passed through a bio - gel p - 6 column pre - equilibrated with buffer b , and then portions ( 25 l ) were immediately diluted with 6 m guanidine hcl or 8 m urea to denature protein and release the bound arsenicals , which were determined as described above . has3mt has three tryptophan residues at positions 73 , 203 , and 213 ( numbering is according to the translated cdna sequence ) ( figure s3 ) . to obtain a single - tryptophan derivative of has3mt , three double - tryptophan mutants were prepared by changing two of the three tryptophan residues at each position ( table s2 ) , creating single - tryptophan derivatives trp73 ( w203l / w213y ) , trp203 ( w73r / w213y ) , and trp213 ( w73r / w203y ) by site - directed mutagenesis . trp73 fusion protein was incubated with thrombin ( 0.7 u / mg fusion protein ) in a buffer consisting of 0.14 m nacl , 2.7 mm kcl , 10 mm na2hpo4 , 1.8 mm kh2po4 , and 1 mm tcep , ph 7.3 , at 23 c for 18 h. following the cleavage reaction , the trp73 enzyme was purified at 4 c using glutathione sepharose 4b ( ge healthcare , usa ) following manufacturer s instructions . fluorescence measurements were performed on a temperature - controlled quantamaster uv vis qm - 4 steady state spectrofluorometer ( photon technology international , birmingham , nj ) at 25 c . for steady - state measurements , samples were excited at 295 nm to excite tryptophan , and emission was set at 336 nm for time - based data acquisition . spectra were corrected for background fluorescence and raman scattering by subtracting buffer spectra . the buffer used was 50 mm mops and 0.5 m nacl , ph 7.5 . for determination of relative binding of free metalloids , as ( iii ) and mas ( iii ) , and preformed gsh conjugates , fluorescence spectra were acquired at the indicated concentrations of arsenicals in the presence and absence of gsh . to obtain binding rates , time - based fluorescence quenching data were fitted to a single exponential decay isotherm using prism 6 ( graphpad software inc . ) . a homology model of has3mt was built on the structure of phas ( iii ) - bound cmarsm ( pdb i d : 4ku9 ) using a fully automated protein structure homology modeling server swiss - model ( http://swissmodel.expasy.org/ ) . the four conserved cysteine residues ( cys32 , cys61 , cys156 , and cys206 ) ( residue numbers are based on the has3mt sequence ) are present in the model structure . the model structure with residues 44371 ( residue numbers are based on the cmarsm sequence ) from phas ( iii ) - bound cmarsm was used as a template , and the final homology model incorporated 308 of those 328 residues . in silico docking with sam was carried out using the patchdock server . the docked has3mt model with sam was superimposed with the as ( iii ) - bound structure of cmarsm ( pdb i d : 4fsd ) to acquire the arsenic atom in the as ( iii ) binding site of has3mt . in two prior studies , human as3mt was expressed from a cdna clone and purified after heterologous expression in e. coli . in both cases , methylation was assayed using molar ratios of as3mt / as ( iii ) of either 1:1 or 3:1 for extended periods of time . with stoichiometric or higher ratios of enzyme to substrate , not more than a single cycle of methylation is possible , so it is not know whether either construct could attain steady state , the most commonly used approach to enzyme kinetics . we took a different approach to the generation of purified as3mt that could work at catalytic rather than stoichiometric concentrations . the sequence of the cdna that had been used by others to produce has3mt was chemically synthesized . the key feature of the chemical synthesis was an increase in the codon usage bias for e. coli by upgrading the codon adaptation index from 0.64 to 0.88 . in addition , the gc content was optimized , and stem - loop structures were disrupted to increase ribosome binding and the half - life of the mrna . the stem - loop structures , which impact ribosomal binding and stability of mrna , were broken . the final product has a total of 662 residues with 366 of the as3mt residues unchanged from the cdna sequence , a fusion with glutathione s - transferase at the n - terminus to improve solubility including tandem thrombin and enterokinase sites , and eight histidines at the c - terminus for purification . the changes in the synthetic sequence from that of the cdna sequence are highlighted in figure s1 , and the sequence of the protein is shown in figure s2 . intrinsic tryptophan fluorescence has been extensively exploited in examining arsenic binding in arsenic detoxification proteins . has3mt has three tryptophan residues at positions 73 , 203 , and 213 ( figure s3 ) . to obtain a single - tryptophan derivative of has3mt , three double - tryptophan mutants were prepared by changing two of the three tryptophan residues at each position ( table s2 ) , creating single - tryptophan derivatives trp73 ( w203l / w213y ) , trp203 ( w73r / w213y ) , and trp213 ( w73r / w203y ) . the gst tag , which contains four tryptophan residues , was removed by thrombin cleavage , as described in the materials and methods . of the three single - tryptophan derivatives , only the trp73 derivative reported binding of arsenicals with a quenching of protein fluorescence . the observed rate of quenching by preformed as ( gs ) 3 to has3mt was faster than could be measured accurately with our fluorometer ( figure 1a , curve 5 ) . the fluorescence signal slowly increased , but addition of gsh to the buffer stabilized the quenching ( figure 1a , curve 6 ) . we interpret this result as the as ( gs ) 3 complex dissociating when diluted into the assay buffer , and that gsh in the buffer prevents dissociation . in contrast , the rate of quenching with inorganic as ( iii ) was extremely slow ( figure 1a , curve 3 ) , requiring approximately 10 min to produce the same quenching as that produced by as ( gs ) 3 in 1 s , but the quenching by as ( iii ) could be accelerated by addition of gsh to the buffer ( figure 1a , curve 4 ) , which we interpret as conjugate formation in the assay buffer . when the quenching of tryptophan fluorescence was fitted to a single exponential decay isotherm , the rate with inorganic as ( iii ) in buffer containing gsh ( figure 1a , curve 4 ) was approximately 130-fold faster than the rate in the absence of gsh ( figure 1a , curve 3 ) . effect of as ( gs ) 3 and mas ( gs ) 2 on the fluorescence of trp73 has3mt . following removal of the gst tag , intrinsic protein fluorescence of trp73 has3mtwas assayed at 25 c in degassed buffer , as described in the materials and methods . as noted , 5 mm gshmetalloids were added at a concentration of 1 mm to 1 m trp73 has3mt . additions : curve 1 , no addition ; curve 2 , as ( v ) ; curve 3 , as ( iii ) ; curve 4 , as ( iii ) with gsh in the buffer ; curve 5 , as ( gs ) 3 ; curve 6 , as ( gs ) 3 with gsh in the buffer . additions : curve 1 , no addition ; curve 2 , mas ( v ) ; curve 3 , mas ( iii ) ; curve 4 , as ( gs ) 3 with gsh in the buffer ; curve 5 , mas ( gs ) 2 with gsh in the buffer . fluorescence quenching with mas ( iii ) ( figure 1b , curve 3 ) was slow compared to that with mas ( gs ) 2 , but it was faster than with inorganic as ( iii ) . fluorescence quenching could be accelerated by addition of gsh to the buffer ( figure 1b , curve 4 ) , which was similar to quenching with preformed mas ( gs ) 2 ( figure 1b , curve 5 ) , but both were too fast to quantify . clearly , binding of glutathione conjugates is extremely rapid , but detailed rate determinations will require stopped - flow analysis . initial studies investigated methylation of as ( iii ) by has3mt in reaction mixtures in which physiological and nonphysiological reductants were employed . under all conditions , as ( iii ) was methylated to both mas and dmas , but the extent of methylation and the ratio of dmas / mas varied ( figure 2 ) . in these assays , no differentiation was made between trivalent and pentavalent products because the reactions were terminated by addition of h2o2 , which oxidizes all arsenicals to their pentavalent forms . as described below , this was necessary because a significant percentage of the total arsenic remained bound to the enzyme . following oxidation with peroxide , all of the arsenic could be recovered . in human populations , individuals with higher conversion to dmas have lower rates of bladder cancer and other arsenic - related diseases . mas ( iii ) is considered to be more toxic than dmas ( iii ) , and a higher fraction of mas excreted in urine correlates with arsenic - related diseases . people with more rapid methylation to dmas may have more rapid clearance and be less susceptible to diseases . on the basis of those considerations , we define optimal has3mt activity as conditions that resulted ( 1 ) in the greatest total methylation and ( 2 ) produced the highest ratio of dmas to mas . under the conditions employed , has3mt showed the highest activity with the combination of cysteine and the artificial reductant tcep . note that nearly all of the as ( iii ) was methylated with an as ( iii ) / has3mt ratio of 10 , the first example of multiple rounds of catalysis by purified has3mt . with possible physiological reductants , high activity was observed with addition of purified trx plus a trx - regenerating system consisting of naph and tr ( termed the trx system ) . with the trx system , the dmas / mas ratio was similar to that with tcep alone ( 5.57.3 ) . addition of gsh to either tcep or the trx system both increased total methylation and the dmas / mas ratio ( 7.011.7 ) . thus , gsh is not a particularly good reductant but might play a different role than trx , such as forming the as ( gs ) 3 substrate . the reaction containing 1 m has3mt , 1 mm sam , 10 m as ( iii ) , and the indicated reductants was incubated for 90 min at 37 c . the reactions were terminated by addition of 10 % ( v / v ) h2o2 to oxidize all arsenic species , which were speciated by hplc - icp - ms . reductants ( final concentrations ) : 5 mm gsh , 5 mm cysteine , 1 mm tcep , 10 m trx ( + 3 m thioredoxin reductase and 0.3 mm nadph ) , or mixtures of those as indicated . open bars ( left ) , inorganic arsenic ; left - slanted bars ( middle ) , mas ; right - slanted bars ( right ) , dmas . the time course of as ( iii ) methylation over a 3 h period was determined using gsh and the trx system ( figure 3a ) . the production of mas was linear over the first 10 min , reaching a plateau at 30 min and decreasing to nearly zero after 180 min . at this point , mas accounted for approximately about 15 % of the total arsenic in the reaction mixture . the production of dmas had a lag of approximately 10 min and then increased until 97 % of the total arsenic was present as dmas . haldane steady - state assumption of enzyme catalysis , which predicts a precursor product relationship for an irreversible reaction . in this case , the immediate product is mas , which disappears as it is converted to the major product dmas . under similar conditions , the native enzyme from the cdna construct exhibited little methylation activity ( figure 3b ) . when both synthetic and native enzyme were present at catalytic concentrations ( 1 m enzyme and 10 m as ( iii ) ) , little dmas was produced by the native enzyme after 2 h , compared with 80 % conversion with the synthetic enzyme . thus , the synthetic enzyme is active when present in catalytic concentrations , whereas the purified native enzyme is not . although we can not eliminate other possibilities , a logical inference is that they differ in conformation , perhaps because the native enzyme does not fold as well as the synthetic enzyme , which was optimized for e. coli expression . one possible explanation is that the native gene has a total of 17 rare codons for arg , leu , ile , and pro that were corrected in the synthetic gene . that could slow the rate of translation and hence the rate of folding of the native protein . the reaction mixture ( 1.5 ml ) containing 1 m of either purified synthetic ( a ) or native ( b ) has3mt , 1 mm sam , 5 mm gsh , 10 m trx , 3 m tr , 0.3 mm nadph , and 10 m as ( iii ) was incubated at 37 c . samples were withdrawn at the indicated times , and the reaction terminated by addition of 10 % ( v / v ) h2o2 , final concentration , and analyzed by hplc - icp - ms . after 10 min at 37 c , synthetic has3mt methylated as ( iii ) to soluble mas ( iii ) , with little mas ( v ) observed ( figure 4a ) . however , at early times the majority of the arsenic appeared to be insoluble , and we predicted that it is bound to the enzyme . to examine this possibility , as ( iii ) methylation was carried out for 10 min with concentrations of enzyme ( 5 m ) and as ( iii ) ( 20 m ) higher than in the usual assay conditions to obtain sufficient enzyme - bound form . unbound arsenic was removed , and the protein with bound arsenicals was denatured with guanidine hcl or urea to release the protein - bound arsenicals ( figure 4b ) . when a protein is denatured with guanidine hcl or urea , it is unfolded , disrupting the secondary and tertiary structures . because substrate binding sites in enzymes are composed of amino acid residues that are brought together in precise distances and geometries , unfolding of the protein will destroy the binding site and release noncovalently bound ligands . denatured protein was removed by filtration , and the filtrate was speciated by hplc - icp - ms . . a small amount of mas ( v ) was also observed , but in control assays , a similar amount of mas ( iii ) was nonenzymatically oxidized to mas ( v ) . purified has3mt ( 1 m ) was incubated at 37 c with 10 m as ( iii ) containing 5 mm cysteine and 1 mm sam for the indicated times . protein was removed , and the soluble arsenicals were speciated by hplc - icp - ms . purified has3mt ( 5 m ) was incubated at 37 c with 20 m as ( iii ) containing 5 mm gsh , 1 mm sam , 10 m trx , 3 m tr , and 0.3 mm nadph . after 10 min , samples were separated through a bio - gel p - 6 spin column . portions ( 25 l ) were diluted with 6 m guanidine hcl or 8 m urea to final concentrations of 4 m to denature the protein and release the enzyme - bound arsenicals , which were analyzed by hplc - icp - ms . as ( iii ) sam methyltransferases have four conserved cysteine residues ( figure s3 ) , cys32 , cys61 , cys156 , and cys206 , in has3mt . the cdna clone lacks the last nine residues of the actual has3mt sequence , including three cysteine residues , but there are seven other nonconserved cysteines ( cys72 , cys85 cys226 , cys250 , cys271 , cys334 , and cys360 ) . of these nonconserved residues , cys72 , cys85 , and cys250 were altered to serine residues , and cells expressing the c72s , c85s , and c250s derivatives retained the ability to methylate as ( iii ) ( figure 5a ) . when the conserved cysteines were altered to serine residues , and cells expressing the c32s , c61s , c156s , and c206sthe c32s , c61s , c156s , c206s , and c32s / c61s derivatives were expressed , and the activity of the purified enzymes examined . none of the altered proteins was able to methylate inorganic as ( iii ) even after 3 h ( figure 5b ) . in contrast , c32s and c61s retained the ability to methylate mas ( iii ) ( figure 6 ) , whereas neither c156s nor c206s were able to do so ( data not shown ) . although the results of mutagenesis are always open to interpretation , these observations indicate that cys156 and cys206 are essential for both the first and second cycles of methylation , whereas cys32 and cys61 are required for the first methylation but not the second . thus , there appears to be two classes of cysteine residues : cys32 and cys61 in one class and cys156 and cys206 in the other . ( a ) in vivo methylation of as ( iii ) by wild - type and mutant has3mts . e. coli bl21 ( de3 ) cells bearing vector pet41a ( + ) or plasmids with wild - type or cysteine mutant genes in pet41a - has3mt were grown in 2 ml of luria broth medium in the presence of 20 m as ( iii ) , 0.3 mm iptg , and 50 g / ml kanamycin at 37 c for 12 h. ( b ) methylation of as ( iii ) by purified wild - type and mutant has3mts . methylation of as ( iii ) was assayed at 37 c after 3 h with 10 m as ( iii ) , 1 m has3mt , 1 mm sam , 5 mm gsh , 10 m trx , 3 m tr , and 0.3 mm nadph . methylation of mas ( iii ) by cysteine mutants was assayed at the indicated times at 37 c with 10 m mas ( iii ) , 1 m has3mt , 1 mm sam , 5 mm gsh , 10 m trx , 3 m tr , and 0.3 mm nadph . the reaction was terminated by addition of 10 % ( v / v ) h2o2 , final concentration . protein was removed before analysis , and soluble arsenicals were analyzed by reversed - phase hplc - icp - ms . the c156s and c206s derivatives did not methylate mas ( iii ) ( not shown ) . a homology model of has3mt model was built on the cmarsm structure with bound phas ( iii ) ( pdb i d : 4ku9 ) using the swiss - model fully automated protein structure homology modeling server ( http://swissmodel.expasy.org/ ) ( figure 7 ) . the model quality was estimated on the basis of a qualitative model energy analysis scoring function of 0.64 , which is within the acceptable range . the secondary structural arrangement of has3mt was nearly the same as that of the cmarsm structure , with equivalent metalloid and sam binding elements . this model was superimposed with the as ( iii ) - bound structure of cmarsm ( pdb i d : 4fsd ) to place an arsenic atom in the as ( iii ) binding site of has3mt , and pymol v1 .3 was used to visualize the structural model . the biochemical data demonstrate that the c - terminal pair of conserved cysteine residues ( cys156 and cys206 ) are involved in methylation of both as ( iii ) and mas ( iii ) . the n - terminal conserved cysteine pair ( cys32 and cys61 ) is involved in as ( iii ) methylation but not mas ( iii ) methylation , suggesting a more subtle role in the catalytic cycle . in the model , cys156 and cys206 form an as ( iii ) binding site , with the arsenic atom 2.2 and 2.3 from the sulfur atoms of cys156 and cys206 , respectively . the methyl group of sam was oriented toward the bound as ( iii ) at approximately 3.9 distance . the location of four conserved cys residues are shown along with the bound sam and as ( iii ) . the expanded view shows the four conserved cysteine residues ( in ball - and - stick ) , with cys32 and cys61 in a disulfide bond and cys156 and cys206 binding the as ( blue ball ) atom . sam ( in ball - and - stick ) occupies its binding site with its methyl group ( * ) poised to be donated to the arsenic atom . on the basis of a combination of experimental data and structural modeling , we propose a novel reaction scheme involving a disulfide bond cascade with at least two sequential disulfide bonds : the first between cys32cys61 and the second between cys61cys156 ( figure 8 ) , based on the disulfide bonds observed in the crystal structures of the cyanidioschyzon merolae orthologue ( pdb ids : 4ku9 and 4fr0 ) . the catalytic cycle for the first two rounds of methylation can be summarized in eight steps . ( 1 ) in the first round of methylation , has3mt binds as ( iii ) in a series of three thiol transfer reactions from as ( gs ) 3 , which is the preferred substrate ( figure 1 ) . ( 2 ) the methyl group of sam is attacked by the arsenic lone pair , ( 3 ) which leads to formation of a transient positively charged pentavalent mas ( v ) intermediate . ( 4 ) the role of cys32 ( or cys61 ; at this time , we can not distinguish between them ) is to provide electrons to reduce enzyme bound mas ( v ) to mas ( iii ) and to allow the next round of methylation . by donating electrons to the arsenic , cys32 ( or cys61 ) ( 5 ) the role of trx is to reduce the disulfide bond , consistent with the traditional role of thioredoxins in facilitating reduction of protein cysteine disulfides by thiolthe disulfide bond is reduced with trx , and ( 6 ) the enzyme undergoes the next round of methylation , forming a transient positively charged pentavalent dmas ( v ) intermediate , ( 7 ) which is reduced to dmas ( iii ) by cys61 , forming a cys61cys156 disulfide . ( 8 ) the disulfide is reduced by trx , regenerating the enzyme and releasing the major soluble product , dmas ( iii ) . finally , in urine , exposure to air nonenzymatically oxidizes dmas ( iii ) to dmas ( v ) . thus , the substrates and products are all trivalent , as predicted by hayakawa et al . , but the arsenic undergoes a cycle of oxidation and reduction , as hypothesized by challenger , but only when it is enzyme - bound . instead , as ( gs ) 3 serves as the arsenic donor to the enzyme , as hypothesized by hayakawa et al . , advantages of this pathway are that it explains current results with as ( iii ) sam methyltranferases and reconciles the proposals of challenger and hayakawa et al. proposed has3mt reaction scheme : ( 1 ) in the first round of methylation , has3mt binds as ( iii ) in a series of three thiol transfer reactions from as ( gs ) 3 ; ( 2 ) the methyl group of sam is attacked by the arsenic lone pair ; ( 3 ) a pentavalent mas ( v ) intermediate is formed and ( 4 ) reduced to an enzyme - bound mas ( iii ) intermediate by cys32 with formation of a cys32cys61 disulfide ; ( 5 ) the disulfide is reduced with trx , and the enzyme undergoes the next round of methylation , ( 6 ) forming a pentavalent dmas ( v ) intermediate , ( 7 ) which is reduced to dmas ( iii ) by cys61 . this form is a cys61cys156 disulfide , which ( 8 ) is reduced by trx , regenerating the enzyme and releasing the major soluble product , dmas ( iii ) . finally , in air , trivalent dmas ( iii ) is nonenzymatically oxidized to dmas ( v ) . arsenic is clearly a health hazard , but is it inorganic or methylated arsenicals that produce the risk ? the answer depends in large part on the products of as3mt , the enzyme that methylates arsenic in liver and other organisms . there are two schools of thought on this matter . the original proposal by challenger in the 1940s involved a series of oxidative methylations such that the substrates were trivalent arsenicals and the products were pentavalent . a more recent proposal by hayakawa et al . suggests that both the substrates and products are trivalent , a key difference between the two major proposals . if hayakawa et al . is correct , then the products are more toxic and carcinogenic than the inorganic as ( iii ) substrate . challenger was ahead of his time since nothing was known of the very large superfamily of methyltransferase enzymes in the 1940s . members of that superfamily append a methyl group from sam to acceptor groups by sn2 displacement mechanisms , involving attack of a nucleophile on the methyl group of sam with inversion of configuration and concomitant release of sah . methyltransferases are categorized on the basis of the electron - rich , methyl - accepting atom , usually o , n , c , or s. these enzymes have been studied in exquisite detail for more than 50 years . they all have a conserved sam binding fold and use a common enzymatic mechanism of methyltransfer , where sam serves as a potent alkylating agent with destabilization of the sulfonium ion . while challenger proposed a series of oxidations and reductions along with three rounds of methylations , none of the o - , n - , c - and s - methyltransferases oxidizes their substrates , and no one has demonstrated the presence of a pentavalent arsenic intermediate bound to as3mt or its orthologues . lysine and arginine methyltransferases are good models for arsenic methyltransferases , as they carry out three very similar methyl transfers without oxidation of the nitrogen . in summary , methyltransferases methylate their substrates without oxidation . nature is conservative , and there is no reason to consider that as3mt would use a different enzymatic mechanism from that of any other member of the superfamily . yet , a major chemical difference between the metalloid arsenic and the nonmetal atoms ( o , n , c , s ) acceptors of the methyl group is its redox activity . for that reason , there is the possibility that as ( iii ) in the metalloid binding site of has3mt becomes oxidized during the catalytic cycle and is reduced again by donation of electrons from the conserved cysteine residues . thus , we propose the formation of the transient pentavalent intermediates shown in steps 3 and 6 of our proposed reaction cycle ( figure 8 ) . however , it is not clear if pentavelent intermediates are obligatory components in the mechanism or side reactions that are the consequences of oxidation . regardless of whether as3mt catalyzes alternation between reduced substrates and oxidized intermediates , transient trivalent intermediates are likelyto be easily oxidized , and there must be a mechanism to keep them reduced . in either case , the disulfide bond cascade that takes place using the conserved cysteine residues of as3mt is a novel feature of as ( iii ) sam methyltransferases that differentiates it from other members of the methyltransferase superfamily . this is very reasonable because gsh , the major thiol in cells , is present at millimolar concentrations and reacts readily with as ( iii ) to form the triglutathione complex inside cells . although we have no data on methylation in any of those organisms , we can predict that they will be able to use other as thiol conjugates . dithiols can readily abstract as ( iii ) from as ( gs ) 3 , so it is also reasonable that as ( gs ) 3 is able to donate as ( iii ) to conserved cysteine residues in has3mt . the as ( gs ) 3 complex is unstable in vitro , so it is challenging to observe its interaction with enzymes . quenching of intrinsic protein fluorescence by arsenicals in single - tryptophan derivatives has been shown to reflect binding . using single - tryptophan derivates , we examined the transfer of as ( iii ) from as ( gs ) 3 to the binding site in the arsd metallochaperone and the cmarsm orthologue of has3mt . we took a similar approach with has3mt by introduction of a single tryptophan , trp73 , adjacent to the predicted as ( iii ) binding site . the results are striking : free inorganic as ( iii ) binds over a period of minutes , whereas preformed as ( gs ) 3 binds in seconds . similarly , mas ( gs ) 2 bound faster than mas ( iii ) . an enzyme that takes minutes to bind its substrate is not a very useful catalyst . if as ( iii ) was added to gsh - containing buffer , quenching was enhanced relative to that with gsh - free buffer , indicating formation of the conjugates during the course of the assay . even as ( gs ) 3 quenched fluorescence faster when the buffer contained gsh , suggesting that the conjugate dissociates when diluted into gsh - free buffer but is stabilized when the buffer contains gsh . these results are most consistent with the glutathione conjugates of inorganic and methylated arsenicals serving as the source of arsenic for has3mt .\noutput:\n" }, { "from": "agent", "value": "a synthetic gene encoding human as ( iii ) s - adenosylmethionine ( sam ) methyltransferase ( has3mt ) was expressed , and the purified enzyme was characterized . the synthetic enzyme is considerably more active than a cdna - expressed enzyme using endogenous reductants thioredoxin ( trx ) , thioredoxin reductase ( tr ) , nadph , and reduced glutathione ( gsh ) . each of the seven cysteines ( the four conserved residues , cys32 , cys61 , cys156 , and cys206 , and nonconserved , cys72 , cys85 , and cys250 ) was individually changed to serine . the nonconserved cysteine derivates were still active . none of the individual c32s , c61s , c156s , and c206s derivates were able to methylate as ( iii ) . however , the c32s and c61s enzymes retained the ability to methylate mas ( iii ) . these observations suggest that cys156 and cys206 play a different role in catalysis than that of cys32 and cys61 . a homology model built on the structure of a thermophilic orthologue indicates that cys156 and cys206 form the as ( iii ) binding site , whereas cys32 and cys61 form a disulfide bond . two observations shed light on the pathway of methylation . first , binding assays using the fluorescence of a single - tryptophan derivative indicate that as ( gs ) 3 binds to the enzyme much faster than inorganic as ( iii ) . second , the major product of the first round of methylation is mas ( iii ) , not mas ( v ) , and remains enzyme - bound until it is methylated a second time . we propose a new pathway for has3mt catalysis that reconciles the hypothesis of challenger ( ( 1947 ) sci . prog . , 35 , 396416 ) with the pathway proposed by hayakawa et al . ( ( 2005 ) arch . toxicol . , 79 , 183191 ) . the products are the more toxic and more carcinogenic trivalent methylarsenicals , but arsenic undergoes oxidation and reduction as enzyme - bound intermediates ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: celiac disease is a life - long gluten - sensitive immune - mediated disorder affecting the small intestinal mucosa . reviews have recently appeared focused on prevalence , diagnosis , pathogenesis and treatment .1,2 the disorder is thought to be restricted to genetically - susceptible individuals , and has been likened to an iceberg disease , since subclinical presentations with few or no intestinal symptoms are becoming more readily recognized . common or classical features include diarrhea and weight loss , but celiac disease is now often first detected in those presenting with a wide array of clinical disorders such as iron deficiency anemia , osteoporosis , conditions , like dermatitis herpetiformis or autoimmune thyroiditis , and even some neurological disorders , including dementia .3,4 this variability in the initial clinical presentation appears largely related to genetic and immunological factors , age of onset , extent and degree of small intestinal mucosal inflammation , gender , and familial nature .5 finally , and particularly in recent years , celiac disease has appeared in an epidemic pattern ,6 possibly related to age of introduction of dietary gluten , specific infections , medication use and supplements .7 diagnosis , particularly in adults , depends on an initial small intestinal biopsy that shows characteristic or typical pathological features of untreated celiac disease . as the disease is a gluten - dependent disorder , improvement on a gluten - free diet is also critically essential .3 biopsy of the small intestine has limitations , particularly if poorly oriented specimens are submitted in fixative by the clinician for laboratory processing , sometimes leading to tangential sectioning and very difficult biopsy interpretation by even expert pathologists . predisposing genetic factors , including human leukocyte antigen markers , hla dq2 and hla dq8 , may be present and serological changes , including antibodies to tissue transglutaminase antigen ( ttg ) , are usually evident . serological studies have also often been employed as a screening tool for celiac disease , particularly for population studies , or for clinical case finding since biopsy changes are usually present with a positive serological test . however , the presence of ttg antibodies alone is not definitive for diagnosis of celiac disease . false negative tests may result ( particularly with immunoglobulin deficiency syndromes , i.e. , iga deficiency ) and even strongly positive ttg tests without biopsy evidence for celiac disease have been reported .8 quantitative ttg assessment may also be helpful since there may be a correlation with the degree of biopsy change and some , but not all , believe that reduced ttg titers on a gluten - free diet may be reflective of clinical improvement and permit assessment of diet compliance . in recent years , guidelines have also appeared suggesting a diagnostic approach .9 a biopsy showing the typical pathological features of celiac disease followed by a clear response to a gluten - free diet is essential . empirical use of a gluten - free diet without an initial biopsy , even if believed to be symptomatically helpful , is not recommended . some of the most intriguing information has emerged in recent years owing to archeological studies . celiac disease may have developed as a distinct disorder with the transition of hunter - gatherer groups into human workforces capable of agriculture . neolithic revolution10 is believed to have permitted competitive survival over other hunter - gatherer groups owing to more secure food supplies . over time , celiac disease has emerged as a major clinical disorder , currently thought on the basis of serological studies to affect up to about 2 % of most genetically - predisposed human populations .11 the gobleki tepe in southeastern turkey is now recognized as one of the most important modern archeological discoveries impacting on history and development of humans , and disorders , like celiac disease .12 here , recent excavations led not only to important information on origins of highly complex and ritualized societies , but also , as the cradle of agriculture , an appreciation for a high concentration for several wild forms of early domesticated plant species with an overlapping distribution , including wild forms of einkorn and emmer wheat , barley and other neolithic founder crops . later dna fingerprinting studies also established a clear relationship with this wild einkorn wheat species and other modern forms of grains that have evolved with increased and more immunogenic gliadin content .13 in 1856 , francis adams14 delivered a lecture to the sydenham society ( based on translation of a greek dialect ) providing an account of the clinical features of celiac disease along with recommendations for treatment by a greek physician , aretaeus of cappadocia , in the second century ad . coeliac , derived from the greek , koiliakos ( meaning abdominal ) to detail a case record of celiac disease including symptoms of diarrhea and malabsorption . subsequently , another case from antiquity was later suspected by italian investigators in a young woman from the first century ad in a region also apparently exposed to wheat cultivation methods .15 much later , in 1888 , samuel gee ,16 a physician working at the children s hospital on great ormond street in london , provided the first modern clinical description of celiac disease in children , noting that the disorder might occur at any age , and suggested that attention to diet might ultimately lead to a cure . he also recorded a child that improved with a diet of mussels , followed by relapse after the mussel season ended . in 1924 , haas17 from the united states published positive results with a banana diet , a popular treatment for decades . subsequently , dicke and his colleagues from the netherlands provided clinical and laboratory evidence for gluten - free diet therapy , based on starvation and re - feeding effects on growth of children during the second world war as well as measured endpoints for small intestinal absorption , including calculated coefficients of fecal fat absorption .18 in 1954 , paulley19 from the united kingdom detailed pathological changes in the small intestine based on surgical specimens from patients with steatorrhea . later technological developments made the small bowel more accessible for direct imaging and pathological evaluation . in most recent years , new data has emerged on virtually every aspect of celiac disease , including potentially important and novel treatment options .20 interestingly , even now , transition from food - gathering to food - producing societies continues . for example , some immune - mediated disorders , including celiac disease , have only recently been reported in the coast salish first nations populations on the west coast of canada .21 these indigenous peoples were a culturally complex society that benefited from a temperate zone maritime climate , living in permanent villages of more than 1,000 residents with social stratification , including slaves and ranked nobility , multiple linguistic dialects and a distinctive art style . the coast salish lived largely on fish , fruits and berries without soil cultivation methods . subsequently , potato and wheat cultivation methods were likely introduced through russian , spanish or british settlements from alaska , california and eventually the fraser river valley , associated with the hudson s bay company . this has been hypothesized to have resulted in a rapid change in the environment , including the emergence of wheat cultivation methodologies , thought to be a critical element in development of celiac disease .22 celiac disease presents as a spectrum of gluten - sensitive mucosal change , noted earlier in this journal , where representative photomicrographs can also be located .23 this spectrum of celiac disease may be classified into a variety of clinical presentations . classical celiac disease is usually recognized in children or adults with diarrhea , weight loss and textbook clinical changes of malabsorption . in theseextraintestinal features dominate and include changes such as iron deficiency anemia , fracture associated with osteopenia , peripheral neuropathy , infertility , abnormal liver chemistry tests , or skin rash characterized as dermatitis herpeformis . subsequent evaluation reveals typical biopsy changes of untreated celiac disease , usually with positive serological studies . latent celiac disease may be defined by the presence of a predisposing gene , such as , hla - dq2 and / or hla - dq8 , associated with architecturally - normal intestinal biopsies , sometimes with increased numbers of intraepithelial lymphocytes . biopsy studies in dermatitis herpetiformis patients and no apparent changes of celiac disease showed some intriguing results .24 in these , a high gluten - containing diet induced mucosal inflammatory changes in the small intestine typical of celiac disease while a gluten - free diet then caused resolution of intestinal symptoms and improvement in induced small intestinal mucosal morphological changes .24 similar results , using blinded biopsy specimens , in a patient with lymphoma and latent celiac disease were also noted .25 refractory celiac disease usually occurs after age 50 years in already well documented celiac disease . in these , recurrent symptoms and biopsy changes occur despite strict diet adherence .26,27 it is critical here for clinicians to note that if no response to a gluten - free diet has ever been demonstrated , celiac disease may not have ever been present . sprue - like enteropathy or unclassified sprue may be present .26,27 this is not a refractory form of celiac disease , but represents an increasingly recognized broad clinical and pathological spectrum of possibly unrelated disorders that do not respond to a gluten - free diet . for example , neonates with the onset of diarrhea days to months following birth have been discovered to have microvillus inclusion disease . altered small intestinal mucosal structure occurs and histochemical staining with periodic acid - schiff reagent typically suggests subapical inclusions in villus enterocytes .28 confirmatory ultrastructural studies reveal variable loss of the epithelial cell microvilli , microvillus inclusions and subapical vesicles . most recently , a form of variant microvillus inclusion disease has been described with a loss of syntaxin 3 , an apical receptor involved in membrane fusion of apical vesicles in enterocytes .29 moreover , similarfor example , a very distinctive sprue - like enteropathic process in the proximal small intestine has been recorded after colectomy for ulcerative colitis , including those treated with a pelvic pouch reconstruction procedure .30,31 this entity appears to be uncommon , but is probably under - reported . negative ttg antibodies have been noted and changes fail to respond to a gluten - free diet . to date , treatment has been largely empirical relying on significant immunosuppression combined with nutritional support . perhaps the most frequently recognizednew forms of sprue - like enteropathy include drug - induced or medication - related forms of enteropathy that may cause severe diarrhea and nutrient malabsorption . historically , these are not entirely novel , but the list is now expanding . triparanol , for example , was an injected agent used over 50 years ago to induce an experimental animal model of celiac disease .32 it was thought that this agent provoked labilization of lysosomal membranes within enterocytes leading to liberation of intracellular hydrolytic enzyme activities with resultant destruction of enterocytes . a syndrome in rats poisoned with this agent also appeared to respond to a gluten - free diet . table 3 shows an accumulated list of medication classes with examples of some currently used medications that cause sprue - like intestinal changes , potentially mistaken for celiac disease .33 for each , removal of the offending agent ( rather than institution of a gluten - free diet ) results in clinical and histopathological improvement . in future , particular attention to emerging medications will be critical before attributing clinical and pathological changes to celiac disease . historically , studies initially suggested that celiac disease was detected mainly only in infancy and primarily in europe or countries that experienced emigration ( largely from the united kingdom ) to canada and australia .45 initially , it was believed that ireland , in particular , had a high prevalence , particularly in western ireland , specifically , galway , up to 1 in 300 persons .46 a similar experience had also been accumulated in some scandinavian countries . in the united states , however , earlier reports suggested that detection of celiac disease was low .45,47 in more recent years , however , these original perceptions have been altered dramatically . at least , in part , this development reflects widespread serologically - based case finding and screening , particularly in the united states . serologically - based studies have estimated that about 1 % to 2 % of populations in most countries evaluated have celiac disease , particularly in the united states and most european countries .4850 the precision of these studies is not clear , however , since standardization of serologically - based assays , including iga tissue transglutaminase ,51,52 is limited . it has also been noted elsewhere that serological studies have likely overestimated sensitivity and underestimated specificity due to verification bias53 as serologically - negative subjects are rarely biopsied .54 however , these serological studies indicate that rates of undiagnosed disease are significant , even in europe and united states . prevalence data in these countries has recently been summarized .54 in sweden , children have rates of 1:285 and 1:77 , finland , 1:99 and 1:67 , and italy , 1:230 and 1:106 . similar rates have been noted in new zealand , australia , argentina , and israel .5561 in the united states , overall prevalence rates for children and adults were recorded at 1:104 and 1:105 , respectively .48,62 however , ethnic specific data are in the united states are limited . hispanics appear to have a lower prevalence than non - hispanics thought to be related to a low frequency of hla - dr3 , dqb1 * 0201 haplotype .62 similarly , celiac disease is rarely recorded in east asian populations that lack this haplotype , but prevalence rates similar to europe have been noted from the middle east and south asian populations . interestingly , people of the sahara in north africa have the highest prevalence rate although africans ( and african americans ) have very low rates .63 in many countries , there is limited or no data and it has been suggested that interpopulation differences in individual countries may not only reflect genetic factors , including hla susceptibility alleles , but other environmental risk factors , including the geographic and temporal variation in nutritional practices . some of the most intriguing information has suggested a change in the prevalence of celiac disease in recent decades . some believe that celiac disease may be increasing , particularly in north america and europe . in part , some simply reflect increased physician recognition coupled with use of serologically - based testing for screening and case finding . however , a true change in prevalence may have occurred , possibly related to other confounding environmental variables .11,64 in young male military recruits at warren air force base , a low prevalence was suggested based on evaluation of stored frozen sera collected from 1948 to 1952 , compared to more recent control cohorts from olmstead country in 2006 to 2008.64 in an independent report , increasing seroprevalence rates were also noted from 1974 to 1989.65 endoscopic biopsy , rather than serological screening has also been done . routine duodenal biopsies obtained during endoscopic study defined moderate to severe architectural changes typical of celiac disease in 2 % to 3 % of adult canadians referred for investigation .66 interestingly , in this study , environmental factors may have been important as a significant fall in new diagnoses of celiac disease occurred over 2 decades followed by a significant rise during the next decade .66 other long - term studies have also suggested a change in risk in recent decades67 ,68 including a recent report from hangzhou in china suggesting increased detection , possibly because of serological screening .69 a case of celiac disease was also reported from korea .70 similar biopsy - positive asian canadians with celiac disease were previously noted , including a chinese woman .71 a recent extensive study of hla - haplotypes and wheat consumption in different regions of china also suggested that celiac disease occurs more frequently in china than currently reported .72 a particularly high allele frequency of dqb1 * 0201 or dqb1 * 0201/02 occurs in xinjiang in northwestern china , an area largely populated by uygurs and kazaks , rather than han chinese . overall , calculated wheat consumption in china has also increased suggesting that the opportunity for gluten exposure is rapidly increasing . interestingly , wheat consumption appears to be greater north of the yangtze river along the ancient silk road compared to rice consumption regions south of the yangtze river . rural xinjiang seems especially susceptible , as wheat consumption there is relatively high .72 these significant and rapid changes in detection rates , defined by either increased or decreased rates based on use of either serologically - based methods or endoscopic biopsies would not likely reflect genetic factors , but instead , a response to other , possibly , superimposed environmental factors . alterations in cereal production and processing , emergence of new or genetically altered forms of wheat or other grains , childhood infections associated with the so - calledhygiene hypothesis ,7375 breastfeeding or time after birth of initiation of feeding solids ,76,77 even changes in patterns of specialist referral and other factors , including medications , air pollution and cigarette consumption have all been considered . the gluten - free diet has been recommended for treatment of celiac disease for more than a half - century , as a result of the seminal early clinical studies by dicke and colleagues from the netherlands during and after world war 2 , noted earlier .18 however , gluten is ubiquitous and complete avoidance is difficult . in recent decades , per capita consumption of wheat and other processed foods that , in themselves , contain more gluten , have both increased . the gluten - free diet is costly , not universally available and compliance is difficult . a need for an alternative , or at least , added supplemental therapies that might reduce reliance on the gluten - free diet is evident . reduced exposure to gluten components in modern grains that are particularly immunogenic , for example , may be useful .78 modern hexaploid forms of wheat are believed to be more immunogenic , compared to ancient wild or diploid varieties of wheat .79 eventual development of genetically modified grains without significant numbers of immunogenic components may be possible , but this appears to be very challenging . gluten contains many different immunogenic peptide sequences and some , but not all , of the genes responsible are not entirely known and located in different sites in the wheat genome .80 modification may result in a loss of the important baking features of the wheat and there remains a future potential for contamination with wild wheat strains . gluten could potentially be sequestered in the lumen with linear copolymeric binders effectively reducing exposure to the epithelium and limiting its effects . one copolymeric binder , hydroxyethylmethacrylate - co - styrene sulphonate , was shown to complex with gliadin reducing toxicity on intestinal epithelial cells in vitro and in a rodent model in vivo .81,82 human studies are still needed to determine if this approach has merit . another approach involvesordinarily , ingested dietary proteins are hydrolyzed in the lumen by gastric pepsin and pancreatic proteases . in addition , enterocyte peptidases further hydrolyze resultant peptide products into amino acids , dipeptides and tripeptides for enterocyte transport into the portal venous system . proline - and glutamine - containing peptides in glutenit is thought that resulting peptides could induce an immune response in genetically - programmed individuals leading to celiac disease .83,84 prolylendopeptidases derived from some plants and different bacteria ( i.e. , flavobacterium , sphingomonas ) can hydrolyze internal proline - glutamine bonds in a proline - containing peptide85 but may be subsequently inactivated in the acidic milieu of the stomach . prior studies using a combination of a barley - derived endoprotease and prolyl - endopeptidase in powder or tablet form appeared to be stable and caused breakdown of wheat gluten with reduced immune effects .8688 prolylendopeptidase activities derived from aspergillus niger were shown to inhibit a gliadin - stimulated immune response by gluten - specific t - cells .89 in a model system , the majority of hydrolytic activity occurred in the gastric compartment with only limited activity needed in the small intestine .90 specific enzymes derived from other microbial species , have also been shown to be operational in a gastric environment , and have been cloned and characterized .9194 as shown in table 5 , clinical trials were done using alv003 , a novel combination glutenase recombinant orally - administered product . two of these trials ( nct00959114 and nct01255696 ) were published as a randomized , double - blind , placebo - controlled phase 2 trial95 demonstrating that alv003 attenuates gluten - induced small intestinal injury in patients with celiac disease in the context of a gluten - free diet daily containing up to 2 g gluten ( equivalent to approximately one - half standard slice of bread in the united states ) . a different variation on this enzymaticapproach was evaluated in a pilot study of gluten - free sourdough wheat baked goods employing lactobacilli and fungal proteases causing a gluten content of 8 ppm and seemed safe for young celiacs with no changes in hematological , serological or intestinal permeability end points .96 another study compared natural flour baked goods to two hydrolyzed baked good groups . most in the latter two hydrolyzed groups had no clinical , serological , or histological worsening .97 others have employed probiotic preparations , specifically vsl # 3 , a mixture of lactic acid and bifido - bacteria in preliminary studies showing effective hydrolysis of gliadin peptides implicated in celiac disease98 combined with evidence of increased barrier function associated with enhancement of tight junction markers in an animal model .99 a further therapeutic approach has focused on prevention of epithelial tight junction passage of molecules , specifically immunologically - active gluten peptides . in celiac disease , including its most early phases , it has been hypothesized that the intestinal mucosa is leaky with increased paracellular permeability . zonulin is a specific tight junction protein highly expressed in celiac disease that functions together with other transmembrane proteins to regulate permeability of the epithelial barrier .100 gliadin is thought to bind to the chemokine receptor cxcr3 releasing zonulin and leading to increased intestinal permeability .101 larazotide acetate ( at1001 ) is a peptide that antagonizes zonulin by receptor blockade102 and is believed to impair paracellular transport from gliadin peptides and their resultant immunological effects . to date , clinical trials have suggested that larazotide appears to be safe with some symptomatic benefit compared to placebo , but no significant change in intestinal permeability .103 as shown in table 4 , the phase 2 clinical trial has been completed ( nct01396213 ) . once gluten peptides pass through tight junctions , tissue transglutaminase 2 enzyme - induced deamidation occurs . the deamidated peptides each assume negative charges causing an enhanced affinity for the binding grooves on hla - dq2 and / or dq8 molecules located on antigen - presenting cell surfaces . as a result of this process , t - lymphocyte activation and subsequent histopathologic mucosal effects occur . to counteract these effects , different hypothetical approachesone approach may involve blockade of transglutaminase 2 or the specific hla - dq2 and / or dq8 molecules to prevent this peptide binding and resultant immune - related mucosal inflammatory effects . inhibition of in vitro transglutaminase 2 activity inhibits gliadin - specific t - cell clones from patients with celiac disease as well as gliadin - induced proliferations of some types of mucosal lymphocytes .104,105 development of gluten peptide analogues may hypothetically act as hla - dq2 blocking agents by prohibiting binding or access to the binding grooves on antigen presenting cells is another area being considered .106 another novel approach is immune tolerance induction . a peptide vaccine that could promote tolerance of some immunologically - active mucosal cells involved in the pathogenesis of celiac disease may be possible . nexvax peptide vaccine employs three different gluten peptides to can hypothetically lead to tolerance in celiacs . prior studies in hla - dq2 transgenic mice with gluten - sensitive t - cells demonstrated efficacy while patients with celiac disease treated with this agent demonstrated acceptable safety and anti - gluten t - cells . further studies to evaluate efficacy and long - term safety in humans with celiac disease for all of these therapeutic options are clearly needed .\noutput:\n" }, { "from": "agent", "value": "celiac disease is a chronic genetically based gluten - sensitive immune - mediated enteropathic process primarily affecting the small intestinal mucosa . the disorder classically presents with diarrhea and weight loss ; however , more recently , it has been characterized by subclinical occult or latent disease associated with few or no intestinal symptoms . diagnosis depends on the detection of typical histopathological biopsy changes followed by a gluten - free diet response . a broad range of clinical disorders may mimic celiac disease , along with a wide range of drugs and other therapeutic agents . recent and intriguing archeological data , largely from the gobleki tepe region of the fertile crescent , indicate that celiac disease probably emerged as humans transitioned from hunter - gatherer groups to societies dependent on agriculture to secure a stable food supply . longitudinal studies performed over several decades have suggested that changes in the prevalence of the disease , even apparent epidemic disease , may be due to superimposed or novel environmental factors that may precipitate its appearance . recent therapeutic approaches are being explored that may supplement , rather than replace , gluten - free diet therapy and permit more nutritional options for future management ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: diaphragmatic dysfunction likely plays an important role in sepsis - related respiratory failure , a condition which occurs in a large proportion of patients admitted to the icu for severe sepsis . sepsis - induced diaphragmatic dysfunction is a pleiomorphic phenomenon manifested by decreased force - generating capacity of the muscle , an increased susceptibility to fatigue , and the presence of muscle fiber injury . inflammatory mechanisms have been strongly implicated , with oxygen free radicals , nitric oxide or its derivatives , and tnf - being amongst the major mediators identified thus far . chemokines are low - molecular - weight cytokines that play a key role in orchestrating leukocyte trafficking to infected or diseased tissues . the chemokines are subdivided into four main families ( cc , cxc , cx3c , and c ) based upon their structure . increased expression levels of several chemokine ligands and their cognate receptors , particularly of the cc family , have been found in muscle biopsies obtained from animal models and human patients suffering from muscular dystrophy or inflammatory myopathies . in this regard , we have recently reported a marked upregulation of ccr1 and two of its major ligands , rantes ( ccl5 ) and mip - 1 ( ccl3 ) , in the diaphragms of muscular dystrophy ( mdx ) mice and demonstrated a relationship with the degree of muscle infiltration by mononuclear inflammatory cells . in addition to their classical role as leukocyte chemoattractants , the chemokines influence a diverse repertoire of normal and pathophysiologic processes , including myoblast behavior in skeletal muscle repair and tissue responses to oxidative stress . rantes and mip - 1 can also act together with ifn - to synergistically upregulate tnf - , the most prototypical cytokine implicated in sepsis - induced diaphragmatic dysfunction . furthermore , it has recently been demonstrated that the ccr1 - rantes axis is a key modulator of the host immune response to bacterial peritonitis as well as exogenously administered lps . in the present study , our primary objective was to determine whether rantes and mip - 1 , as well as their major receptors , are upregulated within the diaphragm after the induction of sepsis in vivo . to examine this question , we employed two different models of sepsis in vivo , an acute model of systemic lps administration and a more clinically realistic model of sustained sepsis caused by pseudomonas lung infection . we further dissected the cellular mechanisms underlying chemokine upregulation in the septic diaphragm , by examining the responses of primary diaphragm muscle cells to lps stimulation in vitro . more specifically , we sought to ascertain whether these responses could be influenced by inhibiting either free radicals or the nf - b transcription factor pathway , since both have been implicated in sepsis - associated respiratory muscle dysfunction . male c57bl / 6 mice ( charles river , quebec , canada ) aged 810 weeks ( 2326 g ) were studied . anesthesia was achieved with a mixture of ketamine ( fort dodge animal health , fort dodge , ia ) and xylazine ( bayer , shawnee mission , ks ) . two experimental models of infection were used : acute endotoxemia and pseudomonas aeruginosa lung infection . to produce endotoxemia , animals received an intraperitoneal injection of lps ( 25 mg / kg of serotype o55 : b5 ; sigma chemical co. , st louis , mo ) diluted in saline . in previous studies , such a dose has been shown to produce a significant impairment of diaphragmatic force generation . a sham - treated control group underwent the same procedure with an equivalent volume of saline alone , and all mice were euthanized at either 6 or 24 hours after injection . the model of chronic pulmonary infection with p. aeruginosa was performed as originally reported by starke et al . the bacteria were entrapped within agar beads ( 100150 m ) , and the number of viable bacteria was measured by homogenizing the beads and then plating 10-fold serial dilutions on trypticase soy agar plates . sterile agar beads were produced in the same manner but with omission of bacteria and were confirmed to be free of colony - forming units ( cfus ) . the trachea of anesthetized mice was intubated to deliver either bacteria - containing or sterile agar beads to mouse lungs , and the mice were killed at either 2 or 7 days later . two different doses of inoculating bacteria ( 2105 and 1106 cfu ) were studied at 2 days after infection , whereas only the lower inoculating dose was used for the 7 - day time point due to unacceptable signs of ill health at the higher dose in the 7 - day group . the higher dose has been shown to produce a significant impairment of diaphragm force generation 2 days after infection , whereas the lower dose has been shown to produce similar effects 7 days after infection . primary diaphragm and tibialis anterior ( ta ) muscle cell cultures were established as previously described in detail , using single living muscle fibers to isolate adult myoblasts . briefly , excised diaphragm muscle strips were digested ( 0.2 % collagenase ) , followed by trituration to liberate individual fibers . the fibers were transferred into matrigel ( becton dickinson , franklin lakes , nj ) - coated ( 1 mg / ml in dmem ) 6 - well plates . cultures were maintained in dmem with 10 % horse serum and 0.5 % chick embryo extract ( mp biomedical , aurora , oh ) for 4 days , during which myoblasts attached to the substratum . diaphragmatic myoblasts were then expanded in growth medium ( 20 % fetal bovine serum , 10 % horse serum , 1 % chick embryo extract in dmem ) until attaining approximately 75 % confluence . at this point , the cultures were placed in differentiation medium ( 2 % fetal bovine serum , 10 % horse serum , 0.5 % chick embryo extract in dmem ) in order to induce myoblast fusion into differentiated myotubes . all experiments were performed on the fifth day in differentiation medium . for lps stimulation , the cells were washed with dmem and then stimulated during 4 hours with e. coli lps ( 1 g / ml ) . to study the involvement of nf - b , myotubes were treated one hour before lps exposure with pyrrolidine dithiocarbamate ( pdtc ; at 100 m ) ( fisher scientific , nepean , on ) , a compound which inhibits the ubiquitin e3 ligase function required for nf - b activation . to study the potential role of free radicals , myotubes were treated with catalase ( at 2000 u / ml ) or n - acetylcysteine ( nac ; at 10 mm ) ( fisher scientific , nepean , on ) , initiated one hour before lps exposure . because the transfection efficiency of primary muscle cell cultures is very low , a murine myoblast cell line ( c2c12 ) was employed for transfection experiments . c2c12 cells ( 5105 ) were seeded onto 60 mm plates , incubated overnight in growth medium ( dmem - 10 % fbs ) , and transfected the following day at approximately 60 % confluence . to achieve transfection , lipofectamine 2000tm ( invitrogen , carlbad , ca ) and8 g of plasmid dna were combined according to the manufacturer 's protocol . at 48 hoursposttransfection , the cells were trypsinized , replated in 6 - well plates and allowed to attach overnight . the next day the medium was switched to dmem - 2 % hs to induce differentiation , and lps stimulation experiments were performed on differentiated myotubes 5 days later , as described earlier for primary cells . cells transfected with pegfp - c1 ( bd bioscience , clontech , san diego , ca ) , expressing green fluorescent protein ( gfp ) , served as transfection controls . to evaluate transcriptional activity from the rantes promoter , muscle cells were transfected with a firefly luciferase expression plasmid under the control of the rantes promoter ( gift from moriuchi et al . ) . the cells were exposed to lps for 4 hours , then lysed and assayed for luciferase activity . to assess the involvement of nf - b in chemokine gene regulation , dominant negative mutant forms of the ib kinases ( gift from bhakar et al . ) , ikk , and ikk were employed to inhibit nf - b activation . the mrna expression levels of ccr1 and ccr5 as well as their two major ligands , rantes and mip - 1 , were assessed in rna extracted from tissues or muscle cell cultures using trizol ( invitrogen , carlsbad , ca ) . the labelled riboprobes were hybridized with total rna overnight ( 20 micrograms from muscle tissues and 5 micrograms from muscle cell cultures ) and then processed using the manufacturer 's protocol ( bd bioscience , pharmingen , san diego , ca ) . protected mrnas were separated using a 5 % acrylamide gel ( 19:1 acrylamide : bisacrylamide ) . gels were transferred to filter paper and dried under vacuum using a gel drier . dried gels were exposed to scientific x - ray imaging film ( kodak , rochester , ny ) , and the bands were quantified using an image analysis system ( fluorchem 8000 , alpha innotech corp , san leandro , ca ) . all signals were normalized to l32 as a loading control and expressed in absolute arbitrary units . for both in vivo and in vitro studies , 6 independent replicate analyses were performed for each experimental condition and time point , unless otherwise noted . for the same experimental condition , diaphragm and ta were compared using the wilcoxon sign rank test . for the same type of muscle , lps and saline groups were compared using the mann - whitney rank sum test . comparisons between three or more groups were performed using the kruskall - wallis test . when significant , post hoc multiple comparisons were archived using the student - newman - keuls method . the analysis was performed using sigmastat software ( spss , chicago , il ) , and statistical significance was set at p .05 . to ascertain the effects of endotoxemia on ccr1 and ccr5 expression in the diaphragm and ta muscles , total rna was extracted at 6 or 24 hours after lps administration and analyzed by ribonuclease protection assays . a representative autoradiograph showing ccr1 expression levels at 24 hours after lps delivery , as well as group mean data ( expressed in arbitrary units ) for both time points , are provided in figure 1 . it should be noted that for these experiments , all of the rna samples evaluated for a specific time point ( n = 24 ) were loaded onto the same gel in order to ensure that the x - ray exposure conditions were identical . this allowed for valid quantitative comparisons at a given time point but not necessarily between different time points , and thus only the former was subjected to statistical analysis . as can be seen , ccr1 and ccr5 were both expressed at a higher constitutive level in the diaphragm than in the ta limb muscle under control ( saline ) conditions . however , only ccr1 showed upregulation in the diaphragm during sepsis , and this was observed at the 24 - hour time point . interestingly , both ccr1 and ccr5 were significantly upregulated in the ta muscle at 6 hours after lps administration . we next sought to evaluate whether the observed upregulation of ccrs in the septic diaphragm and ta is associated with altered expression of their cognate ligands , rantes and mip - 1 , at the same time points ( 6 and 24 hours ) after lps delivery in vivo . figure 2 shows that the overall patterns of rantes and mip - 1 gene expression responses were similar . hence for both chemokines , increased mrna expression was induced by lps injection in the diaphragm at 6 hours , and levels remained elevated over control values at 24 hours . in addition , under control conditions , the baseline expression levels of both rantes and mip - 1 were significantly higher in the diaphragm than in the ta limb muscle . similarly , the absolute magnitude of mrna expression for both chemokines after lps administration was generally greater in the diaphragm than in the limb muscle . to determine if similar patterns of chemokine upregulation within the diaphragm are observed in another septic situation relevant to the icu setting , namely , gram - negative bacterial pneumonia , a live infection with pseudomonas aeruginosa was introduced into the lungs . two different inoculating doses were studied at day 2 postinfection , whereas only the lower inoculating dose was used for day 7 due to excessive mortality at this time point with the higher dose . figure 3 shows that both rantes and mip - 1 mrna expression were upregulated at day 2 postinfection with the higher inoculating dose ( 10 cfu ) only . in contrast , the lower inoculating dose ( 10 cfu ) also triggered an increased expression of the two chemokines at day 7 postinfection , and this was particularly striking in the case of rantes . interestingly , we did not observe any upregulation of either mip - 1 and rantes within limb muscles under the same conditions ( data not shown ) , and the levels of chemokine upregulation in the diaphragm at both time points after pseudomonas infection were greater ( relative to control ) than following acute lps administration . having shown that both rantes and mip - 1 are upregulated in the diaphragm by two different sepsis models in vivo , we next wished to establish whether stimulation by lps has direct effects on the expression of these chemokines by diaphragm muscle cells in vitro . ribonuclease protection assays were performed to quantify rantes and mip - 1 expression levels in primary diaphragm muscle cell cultures ( differentiated myotubes ) at 4 hours poststimulation with lps . in the absence of lps stimulation , rantes expression by diaphragmatic myotubes was observed , but only at a very low level , whereas mip - 1 was not detectable . however , exposure of the cultured diaphragmatic myotubes to lps markedly upregulated rantes ( see figure 4 ( a ) ) but had no measurable effect on mip - 1 expression . to further explore the mechanism of rantes upregulation by muscle cells after lps stimulation , we transfected c2c12 cells ( skeletal muscle cell line ) with a plasmid containing the rantes promoter linked to a luciferase reporter gene , and the transfected cells were then once again stimulated with lps at the myotube stage . as shown in figure 4 ( b ) , there was a significant increase in luciferase expression in the lps - stimulated group in comparison to nonstimulated control cultures transfected with the same plasmid ( transfection efficiency of approximately 50 % in both groups ) . these data suggest that lps - induced upregulation of rantes expression in muscle cells involves an increased level of transcription from the rantes promoter . because the rantes promoter is a target for the transcription factor nf - b , we also examined the effects of an nf - b inhibitor ( pdtc ) on rantes gene expression in primary cultured diaphragmatic myotubes stimulated with lps . these findings suggest that nf - b plays an important role in lps - induced rantes expression by diaphragmatic myotubes . on the other hand , nac and catalase , two potent antioxidant compounds , had no measurable effects on rantes expression ( figure 5 ( b ) ) , suggesting that the free radical generation which is known to occur in septic diaphragm muscle is not a major factor in lps - induced rantes upregulation . finally , the role of nf - b in the lps - induced rantes gene upregulation within differentiated myotubes was further studied using a strategy of dominant negative inhibition . two different dominant negative constructs were transfected into c2c12 cells in order to inhibit ikk and ikk , which are involved in the alternate and classical nf - b pathways , respectively . figure 6 illustrates and confirms the role of the classical nf - b pathway in lps - induced rantes upregulation by muscle cells . hence when c2c12 muscle cells were transfected with the dominant negative ikk construct prior to lps stimulation at the myotube stage , there was a significant inhibition of subsequent lps - induced rantes expression , whereas ikk inhibition had no significant effect . chemokines are responsible for modulating multiple aspects of the host inflammatory response against infection , such as leukocyte adhesion and migration , inflammatory cell activation , and the balance between type i and type ii cytokine production . serum levels of both rantes and mip - 1 are elevated in septic patients , and modulating the biological activity of these chemokines has been shown to alter the clinical course of sepsis in animal models . two major receptors targeted by rantes and mip - 1 in vivo are ccr1 and ccr5 , which are both expressed by a broad spectrum of leukocytes . the authors and sell et al . have recently demonstrated both expression and function of these receptors in isolated skeletal muscle cells . to our knowledge , this is the first study to demonstrate an upregulation of cc class chemokine receptors and their ligands within septic skeletal muscles . the major findings of our study can be summarized as follows : ( 1 ) diaphragmatic ccr1 gene expression is upregulated in response to acute endotoxemia ; ( 2 ) both acute endotoxemia and pseudomonas lung infection lead to increased expression of the ccr1 ligands , rantes and mip - 1 , and this occurs to a significantly greater extent within the diaphragm as compared to limb muscle ; ( 3 ) lps - induced upregulation of rantes expression by diaphragmatic muscle cells is transcriptionally regulated and dependent upon the nf - b transcription factor pathway , whereas oxygen free radicals do not appear to be involved in this process . in the present investigation , both of these models have previously been shown to be associated with sepsis - induced upregulation of a number of proinflammatory cytokines ( see table 1 ) , along with diaphragmatic dysfunction . the acute administration of lps has the advantage of being a well - established and easily quantifiable septic stimulus , whereas the pseudomonas lung infection model may be considered closer to most clinical situations , since it encompasses additional virulence factors within the bacteria besides endotoxin . interestingly , in both models , the sepsis - induced chemokine upregulation was more marked in the diaphragm than in limb muscles . this pattern of preferential diaphragmatic involvement mirrors the muscle functional impairment and injury observed in several previous studies . moreover , the fact that the diaphragm showed greater constitutive as well as induced levels of chemokine receptor / ligand upregulation is consistent with an emerging concept that the diaphragm may be in certain respects immunologically primed to respond in a more vigorous fashion to inflammatory stimuli , perhaps to aid in its role as a physical barrier to the passage of infectious agents between the peritoneal and pleural cavities . we have recently reported that rantes and mip - 1 are also upregulated to a greater extent in the inflammatory milieu of the muscular dystrophic diaphragm than in limb muscles from the same animals . in the present study , rantes also demonstrated more sustained upregulation than mip - 1 in the chronic inflammatory situation associated with pseudomonas lung infection . this is consistent with previous data showing an important role for rantes in sustaining chronic inflammation . stimulation of cultured primary diaphragmatic ( as well as c2c12 ) muscle cells with lps triggered an upregulation of rantes expression . interestingly , we did not detect an upregulation of mip - 1 within muscle cells following exposure to lps in vitro , suggesting that sepsis - induced mip - 1 expression by the diaphragm in vivo may originate from nonmuscle cell types within the whole muscle . we have previously reported that primary diaphragmatic myotubes also demonstrate significant upregulation of ccr1 but not ccr5 during proinflammatory cytokine stimulation in vitro , which is in keeping with the greater upregulation of ccr1 during endotoxemia shown in the present study . these observations reinforce the idea that skeletal muscle fibers have the ability to behave as immune cells and thus actively participate in the response to various inflammatory stimuli . for example , in cultured human muscle cells , proinflammatory cytokines induce the expression of class i and class ii major histocompatibility molecules . indeed , skeletal muscle cells have the ability to express a large repertoire of immunologically relevant molecules . to begin to dissect the molecular events underlying rantes upregulation within septic diaphragmatic muscle cells , we first determined that the rantes promoter is responsive to lps in skeletal muscle cells , thus pointing to a transcriptional mechanism . we then focused on examining the role of nf - b , a transcription factor that has been shown to activate a large number of proinflammatory genes in various cell types , including rantes . in addition , inhibition of the ikk - dependent nf - b has recently been shown to ameliorate muscle pathology in the setting of muscular dystrophy and after experimentally induced muscle injury . in our study , two distinct methods were used to evaluate the involvement of nf - b : pharmacological inhibition with pdtc and a dominant negative transfection approach . this combination of complementary methods allowed us to inhibit two critical protein complexes which are required for the phosphorylation and degradation of ib : the ikk and e3 ubiquitin ligase complexes , respectively . the sequential actions of these two complexes permit the liberation and subsequent translocation of nf - b into the nucleus in order to activate proinflammatory gene transcription . in keeping with our hypothesis , both pharmacological and dominant negative molecular inhibitions of the ikk - dependent classical nf - b pathway were effective in suppressing lps - induced upregulation of rantes . on the other hand , inhibition of the ikk - dependent alternative nf - b pathway , and blockade of free radicals with the antioxidants nac or catalase , did not have any effect on lps - induced rantes gene expression under the same experimental conditions , strongly suggesting that these pathways were not involved . what are the precise functional roles played by cc - class chemokine upregulation within the septic diaphragm muscle ? the results of our study do not allow this question to be definitively addressed , since this would require a model in which muscle tissue - specific knockout of the receptor - ligand interaction could be achieved in vivo . however , there are a number of plausible scenarios . the most intuitively obvious role for cc chemokines in this setting would be to stimulate the recruitment of inflammatory cells , as has been proposed in several other diseases involving skeletal muscle . for example , in the mdx mouse , a murine model of duchenne muscular dystrophy , the diaphragm exhibits a pronounced infiltration by macrophages and lymphocyctes , which parallels a marked overexpression of rantes and mip - 1 . this is consistent with the inflammatory cell types known to be attracted by these chemokines . in animal models of sepsis , infiltration of the diaphragm by inflammatory cells has been observed in some but not all studies . hence in models of acute endotoxemia and bacterial peritonitis induced by cecal ligation and perforation , macrophage infiltration has been reported in the diaphragm . the presence of inflammatory cells in the diaphragm was associated with contractile impairment and muscle fiber injury , both of which were partially prevented by inhibition of nitric oxide synthase . along these same lines , supinski et al . reported neutrophilic infiltration of the diaphragm after systemic delivery of lps , along with an improvement in diaphragmatic contractility when the superoxide - generating nadph complex was inhibited . however , while we demonstrate in this study that cc chemokine upregulation occurs in the diaphragm during pseudomonas lung infection , we have previously reported that inflammatory cells are not recruited to the diaphragm in this model , suggesting the existence of alternative functions for chemokines in septic skeletal muscle . in thisregard , another recently recognized function of cc chemokines is in the regulation of cytokine production . it has been found that both nk cells and cd8 + t cells use rantes and mip - 1 to help drive the th1 cytokine response . in human monocytes , rantes is able to directly induce the expression of several proinflammatory cytokines / chemokines ( e.g. , il - 1 , mcp - 1 ) and molecules involved in extracellular matrix digestion ( e.g. , mmp - 9 ) as well as its own receptor , ccr1 . in the cecal ligation and perforation model of sepsis , it was recently shown that administration of rantes significantly increases lethality , and this is associated with an increased production of multiple proinflammatory cytokines , which probably underlies the reduction in survival . taken together , these findings suggest that cc chemokines could act in an autocrine or paracrine fashion to upregulate the expression of other proinflammatory mediators within the diaphragm during sepsis , and thereby contribute to contractile dysfunction . there is also evidence for an important contribution of cc chemokines to muscle regeneration and recovery . rantes is reported to act as a chemotactic factor for myoblasts , and gene expression profiling studies have shown an enhanced expression of cc - class chemokines as well as their receptors in injured muscles . other studies have shown that functional recovery from muscle injury is impaired in mice rendered deficient in mcp - 1 or its receptor , ccr2 . our group has recently shown that several cc chemokines , including mip - 1 , are able to stimulate myoblast proliferation . collectively , these data suggest that at least under certain conditions , chemokines may also play a beneficial role in the repair of diaphragmatic muscle fiber injury triggered by sepsis . the ultimate impact of these cc chemokines upon septic diaphragm function is likely dependent upon achieving the appropriate magnitude as well as spatial and temporal equilibrium of chemokine expression .\noutput:\n" }, { "from": "agent", "value": "sepsis - induced diaphragmatic inflammation has been associated with respiratory failure , but the role of chemokines in this process has not been evaluated . here we sought to study the local expression and molecular regulation of the chemokines , regulated upon activation normal t cell expressed and secreted ( rantes ) and macrophage inflammatory protein ( mip ) - 1 , in the murine diaphragm during sepsis . constitutive expression levels of rantes and mip - 1 , as well as their receptors , ccr1 and ccr5 , were significantly higher in diaphragm than limb muscle . sepsis was induced by acute lipopolysaccharide ( lps ) delivery or subacutely by intratracheal administration of live pseudomonas aeruginosa bacteria . both sepsis models triggered a marked upregulation of rantes and mip - 1 in the diaphragm . in vitro , stimulation of diaphragmatic muscle cells with lps also led to rantes upregulation . inhibition of the nf - kb pathway using pharmacologic or dominant negative genetic approaches blocked the lps - induced rantes upregulation , while free radical scavengers had no effect . we conclude that sepsis leads to greatly increased expression of rantes , mip - 1 and their cognate receptors in the diaphragm . manipulation of the nf - kb pathway and other regulators of chemokine expression in the diaphragm could represent a novel method for mitigating the skeletal muscle inflammatory response associated with sepsis - induced diaphragmatic dysfunction ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the nuclear factor kappa b ( nf - b ) family consists of transcription factors activated in response to a variety of cellular stressors . the transcription factor nf - b is a key component of the cellular response to damage , stress , and inflammation . the nf - b proteins consist of 5 subunits , which bind to dna as a dimer ; the most common of these subunits is the p65 / p50 heterodimer . nf - b activation via the canonical pathway is mediated by inhibitory kappa b ( ib ) kinase ( ikk ) , which is activated in response to a variety of pathogenic factors . activated ikk phosphorylates an inhibitory protein , ib , which results in ib degradation and thereby allows nf - b to translocate to the nucleus and to induce the synthesis of proinflammatory molecules . studies that have utilised a direct blockade of the enzymatic activities of ikk , jnk , or p38 mapk have demonstrated the great potential for such treatments to elicit anti - inflammatory effects . selective inhibitors for different signal pathways , including the nf - b cascade , are therefore potentially useful in the treatment of inflammation . we have recently reported that synthetic inhibitors of toll - like receptor 4 ( tlr - 4 ) , stress - activated protein kinase jnk ( sapk / jnk ) , and nf - b signalling ( cli - 095 , sp600125 , and ikk inhibitor xii , resp . ) reduced the in vitro effect of lps on macrophage - like raw 264.7 cells . amongthese three studied inhibitors , the suppressor of the nf - b cascade , ikk inhibitor xii , has been shown to be the most effective antitoxic agent in vitro . the first aim of present study was to determine whether ikk inhibitor xii is effective in vivo and how the effectiveness of this inhibitor is affected when used in combination with other anti - inflammatory agents . to address these knowledge gaps , we used a mouse model of acute septic inflammation induced by lps from the gram - negative bacteria escherichia coli . numerous studies have reported an increase in the production of reactive oxygen species during sepsis . it is well known that mutual cross - talk exists between reactive oxygen species and nf - b signalling . since antioxidants act not individually , but synergistically , a mixture of vitamin e , ubiquinone q9 , and - carotene was added to the animal diet . in addition , in an attempt to gain more insight on the effects of each fat - soluble antioxidant , we studied coenzyme q9 , - tocopherol , and - carotene in cellular model . earlier we have shown that oxidative stress linked with acute inflammation can be prevented by the mixed dietary fat - soluble antioxidants coenzyme q9 , - tocopherol , and - carotene . the second aim of the present study was to test if these antioxidants can reinforce ikk inhibitor xii activity . finally , the third aim of study was screening the anti - inflammatory activity of ikk inhibitor xii in combination with the thymic peptide thymulin . the activity of this peptide has been reported not only in the thymus but also in the bloodstream , affecting extrathymic immune cells . at present , it has been shown that thymic peptides can affect signalling pathways during both normal conditions and systemic inflammation . other authors believe that the mechanisms of the anti - inflammatory effects of thymic peptides , including thymulin , may involve nf - b and p38 signalling cascades , which play crucial roles in inflammation . recently we have demonstrated that thymulin in vitro and in vivo affected the nf - b cascade in tandem with the production of proinflammatory cytokines , nitric oxide , and heat shock proteins in immune cells . we hypothesised that the antioxidants and / or thymulin could act as adjuvants , strengthening the anti - inflammatory effect of ikk inhibitor xii . the first series included seven groups , with each group consisting of 4 mice , and the results of the study are shown on figures 1 and 2 . the second series performed at another point of time , included five groups , with each group consisting of 4 mice , and the results of the study are shown on figures 3 and 4 . male balb / c 8 - to 10 - week - old ( 2527 g ) mice were maintained under standard laboratory conditions ( 2021c , 1014 h light - dark cycle , and 65 % humidity ) with food and water available ad libitum . the standard food pellets contained a balanced diet with proteins , vitamins , and minerals . the procedures followed were approved by the ethics committee of the institution and were in accordance with the guidelines for ethical conduct in the care and use of animals . a diet enriched with - carotene ( 2 mg / kg body weight ) , - tocopherol ( 2 mg / kg body weight ) , and ubiquinone q9 ( 8 mg / kg body weight ) was administered daily for 15 days prior to lps treatment . all antioxidants were purchased from sigma , usa . the antioxidant formula used took into account the approximate levels of these antioxidants in the animals ' tissues , such that each compound did not exceed its physiological level in mice . the antioxidant mixture was stirred into 2 g of pellets and was given daily before feeding at 8 am ; antioxidants were fed to each mouse individually . before morning feeding , animals in the other groups were fed pellets without antioxidants . inflammation was induced by a single intraperitoneal injection of lipopolysaccharide ( lps ) from escherichia coli ( serotype 026 . b6 , sigma , thymulin solution ( 1.5 mg / kg ) was injected intraperitoneally 1.5 hr before lps treatment and was prepared from serum thymic factor ( american peptides , usa ) , to which an equimolar concentration of zncl2 was added . ikk inhibitor xii , at concentrations ranging from 5 to 20 mg / kg was injected intraperitoneally 1 h prior to lps treatment . mice were decapitated 6 h after lps injection in parallel with the corresponding control groups . the blood samples were kept for 35 h at 4 and centrifuged at 200 g ; supernatants were then collected for cytokine assays . lymphocytes from the spleen were isolated in 199 medium ( sigma , usa ) containing 1 % 1 m hepes solution , 100 g / ml streptomycin , and 10 % fetal bovine serum . erythrocytes were lysed in tris - buffered ammonium chloride ( 0.01 m tris - hcl with 0.15 m nacl0 .83 % nh4cl , 9 : 1 ) . after washing , the samples were stored at a concentration of 110 cells / ml in rpmi 1640 medium at 20c until western blotting was performed . elisa development kits for mouse tnf - , il - 1 , il - 6 , il - 17 , il - 10 , and ifn - ( peprotech , usa ) were used . to visualise binding , 100 l of abts green dye ( sigma , usa ) dissolved in 0.05 m citrate buffer ( ph 4.0 ) with 0.01 % hydrogen peroxide was added . the optical density was measured at 405 nm with a plate spectrophotometer ( multiscan ex , thermo electron corporation ) . to prepare specimens ,110 splenic cells were lysed using an ultrasonic disintegrator with constant stirring for 2 min . the proteins in each sample were then precipitated in acetone , solubilised , boiled for 5 min , and stored at 70c . proteins were resolved by electrophoresis over a 10 % page gel and then transferred from the gel onto a nitrocellulose membrane ( ge healthcare , amersham , uk ) in a transblot chamber . after blocking , the membrane was exposed for 2 hr to antibodies against the following mouse proteins : hsp70 antibody ( rabbit anti - mouse hsp 72 , clone spa - 812 , inducible form , stressgen ) , hsp90 antibody ( rabbit anti - hsp90 [ hsp86 ] , stressgen ) , phospho - nf - b antibody ( phospho - nf - b p65 [ ser 536 ] , # 3031 , cell signaling technology , danvers , ma ) , rabbit phospho - ikk / antibody ii ( ser 176/180 ( cell signaling technology , usa ) , rabbit phospho - sapk / jnk antibody to synthetic phospho - peptide sapk / jnk , or rabbit tlr4 antibody ( # 2246 , cell signaling technology , usa ) . after washing , the nitrocellulose membranes were incubated for 1 hr with the anti - rabbit biotinylated antibody ( jackson immunoresearch , west grove , pa ) , and peroxidase - conjugated streptavidin was added for 1 hr . the loading control was a rabbit monoclonal antibody against a synthetic peptide near the carboxy terminus of human glyceraldehyde -3-phosphate dehydrogenase ( gapdh ) ( cell signaling ) . an ecl - plus chemiluminescent cocktail ( amersham / ge ) was then used to develop the blots according to the manufacturer 's instructions , and the blot was then exposed to film . quantitative evaluation of protein bands was then performed using the qapa computer program ( pushchino , russia ) . fifty m ubiquinone , 10 m - tocopherol , or 10 m - carotene were added to the cultivating medium as water - alcohol emulsions ( for q9 and - tocopherol ) or a water - tween 85 emulsion ( for - carotene ) . samples with medium supplemented only with the equivalent amount of alcohol or tween 85 served as controls . the cells were cultivated for 24 h at 37c in a humidified atmosphere containing 5 % co2 . in all cases , the final alcohol and tween 85 concentrations did not exceed 1 % in control or experimental samples . blood glucose levels were assayed in all groups of mice prior to manipulations and at 1 , 2 , and 6 h after lps treatment . during glucose measurement , the tail tip ( 2 - 3 mm ) was excised and massaged to harvest a small volume of blood ( 1.010 l ) which was placed into the hole of a blood glucose test strip ( accu - chek performa , germany ) . glucose measurements were obtained using a rapid blood glucose meter ( accu - chek performa , germany ) . statistical analysis was performed using statistica / win 6.0 software ( tulsa , ok ) . one - way analysis of variance ( anova ) followed by a post hoc tukey test was used to determine the significance of differences among groups , with p values 0.05 considered significant . initial experiments were performed to reveal the abilities of each of used antioxidants ( - carotene , - tocopherol , and ubiquinone q9 ) to eliminate reactive oxygen species in murine peritoneal macrophages . it is well known that oxidative stress linked with lps treatment results in proinflammatory cytokine response , including extremely tnf - production . so , we tested the protective effect of each of antioxidants by measuring the production of tnf - level in lps - treated macrophages as shown in table 1 . the series of observations strongly indicated that separately the addition of the ubiquinone , - tocopherol , and - carotene to the culture medium in vitro significantly decreased the tnf production in lps - treated macrophages . in addition , effect of three mixed compounds was rather more appreciable , indicating synergistic interaction between fat - soluble antioxidants . in each experimental group , blood glucose levels decreased to 70 % 80 % compared to controls one hour after lps treatment , but rapidly recovered to the control level , being unaltered at 2 and 6 h. in addition , no substantial differences in blood glucose levels were found between experimental groups ( data not shown ) . we can assume a glucose - independent mechanism of anti - inflammatory effects of agents studied . to examine the amounts of proinflammatory molecules associated with acute inflammation and the protective effect of the inhibitor and diet , the plasma cytokine concentrations were measured concurrently in seven mouse groups treated with ikk inhibitor xii , dietary antioxidants , or a combination thereof . treatment with lps alone resulted in an expected increase in plasma proinflammatory cytokines ( e.g. , il - 1 , ifn - , and tnf - ) . there was more than 2-fold increase in plasma tnf - levels and a more than 3-fold increase in ifn - levels ( figure 1 ) . this finding agrees with previously reported data that demonstrated that lps in vivo increased il - 10 production in peritoneal mouse macrophages . in mice pretreated with different concentrations of ikk inhibitor xii , plasma cytokine valueswere significantly decreased , and the maximal effect was observed at a concentration of 20 mg / kg . the pretreatment of mice with dietary antioxidants affected cellular responses to lps ; in cells from mice treated with antioxidant - rich diet , plasma cytokine values were reduced ( figure 1 ) . it should be noted that the effects of antioxidants on the inflammatory response measured by cytokine production were less suppressive than the effects induced by the ikk inhibitor ; the difference , however , was statistically significant for il - 1 , il - 10 , and ifn - values . additionally , when mice were simultaneously exposed to the inhibitor and antioxidants , nonadditive effects from the ikk inhibitor and dietary antioxidants were observed . to examine the extent of nf - b activation associated with inflammation , the levels of the phosphorylated dimer p65 / rela and phosphorylated ikk - / were measured by the immunoblotting of splenic lymphocytes . there was a more than 2-fold increase in phosphorylated p65 , which correlated with a significant ( more than 7-fold ) increase in the level of phosphorylated ikk in these cells ( figure 2 ) . the pretreatment of mice separately either with the inhibitor or with dietary antioxidants significantly decreased the phosphorylation of both p65 and ib , and the combination of the inhibitor and antioxidants did not result in an additive effect . to elucidate the role of an essential receptor for lps and tlr4 , we analysed cellular tlr4 levels using western blot analysis . as shown in figure 2 , the addition of lps induced an expected significant increase in tlr4 levels in splenic cells . however , in the cells of mice pretreated with ikk inhibitor xii or with antioxidants , these increases in tlr4 expression were completely ablated , indicating that the tlr4 pathway can be interregulated via nf - b signalling as well as by the redox balance . additionally , to assess the level of stress response in lps - treated mice , the expression of two inducible heat shock proteins , hsp72 and hsp90 - , was studied in splenic lymphocytes . lps induced a 4-fold rise in hsp90 expression and a more than 8-fold increase in hsp72 production ( figure 2 ) . again , the pretreatment of mice with ikk inhibitor xii or with antioxidants resulted in the complete ablation of hsp72 and hsp90 - spikes in cells after injection with lps . additionally , these two simultaneously applied treatments did not have a reciprocal interaction , as demonstrated by the measurement of both heat shock proteins , of cytokines , and of signalling proteins . to determine whether thymulin with or without ikk inhibitor xii can downregulate the in vivo response to lps , the values of plasma il - 6 , il - 17 , ifn - , and tnf - were measured in lps - injected mice using five mouse groups indicated in the legend to figure 3 . note that other panel of cytokines was tested in these experiments based on our previous data on thymulin activity . based on the above results , the optimal concentration of 20 mg / kg inhibitor was used in this experimental series examining the combined effect of thymulin with ikk inhibitor xii . these experiments confirmed that an increase in plasma tnf - levels occurs after lps treatment , supporting the results of the experiments displayed in figure 1 . the pretreatment with thymulin or with ikk inhibitor xii decreased the accumulation of the tnf - in plasma . the concentration of plasma tnf - in mice pretreated with the inhibitor and thymulin together did not significantly differ from that measured in lps - treated mice . there was a more than 3-fold increase in plasma ifn - in mice treated only with lps ; both ikk inhibitor xii and thymulin prevented this increase . the combined effect of the inhibitor and thymulin in preventing lps - mediated increases of plasma ifn - was no greater than the individual activity of each agent . in these experiments , we detected a significant increase in the concentration of il - 6 in lps - treated mice , which was partly but not significantly decreased by pretreating the mice with ikk inhibitor xii or with thymulin , demonstrating that these treatments could not completely ablate plasma il - 6 levels . it is important to note that when these two agents were administered together , il - 6 levels were still not completely normalised . in addition , there was a more than 3-fold increase in plasma il - 17 from lps - treated mice , but the inhibitor and thymulin , alone or in combination , could not prevent the increase in il - 17 ( figure 3 ) . similar to results from the first experimental series , the treatment of mice with lps resulted in the increased phosphorylation of rela and ikk ( figure 4 ) . interestingly , compared to separate treatments with peptide or with inhibitor , the combined treatment with thymulin and the inhibitor resulted in an apparent increase in the protective effect directed towards the prevention of excessive ikk phosphorylation . it has been previously shown that ikk inhibitor xii in vitro affects the sapk / jnk pathway in raw 264.7 cells . to examine the in vivo effects of the inhibitor and thymulin on the activity of sapk / jnk signalling , the levels of phosphorylated sapk / in contrast to linear raw 264.7 cells , which generate two phosphorylated isoforms , jnk1 and jnk2 , ex vivo cells expressed only a single form of phosphorylated sapk / jnk . lps induced an approximately 7-fold increase in sapk / jnk phosphorylation , and in mice separately treated with thymulin or with ikk inhibitor xii , the spike in phosphorylated sapk / jnk significantly decreased . it should be noted that the combined treatment with thymulin and inhibitor resulted in a summation of their effects and the normalisation of sapk / jnk phosphorylation . there was also a reduction in cellular hsp72 expression in cells from inflammation - bearing mice that were pretreated with thymulin or the inhibitor ( figure 4 ) . collectively , these data demonstrate that the pharmacological inhibition of ikk / nf - b and sapk / jnk activation leads to the attenuation of lps - related inflammation . over the last decade , an inhibitor of the nf - b signalling pathway , ikk inhibitor xii , has been discovered and investigated for its clinical potential in inflammatory diseases . this inhibitor is a synthetic small hydrophobic molecule that can freely penetrate into the cell . ikk inhibitor xii , a cell - permeable amino - diarylbenzamide compound , acts as a potential atp site targeting inhibitor against ikk - 1 and ikk - 2 . interestingly , ikk inhibitor xii , a selective inhibitor of nf - b signalling that functions by decreasing nf - b phosphorylation and thus reducing the probability of translocation of the nf - b into the nucleus , also prevented sapk / jnk activation in lps - treated cells ( figure 2 ) . these results coincide with findings demonstrating that sapk / jnk signalling is regulated by the nf - b pathway . indeed , it is generally suggested that nf - b activation plays a critical role in lps - induced responses and that the suppression of nf - b pathway activity prevents its ability to activate the transcription of a wide variety of genes encoding immunologically relevant proteins . it is also known that targeting ikk also may affect other pathways in addition to nf - b . for example , ikk affects p53 , foxo3a , and hif - 1 in addition to nf - b . we demonstrated that the pharmacological inhibition of the ikk / nf - b pathway by ikk inhibitor xii delays the proinflammatory response in lps - treated mice . thus , many processes are shown to be altered in mice undergoing inflammation , including increases in cytokine production , the stimulation of heat shock proteins and tlr4 expression , and the activation of nf - b and sapk / jnk signalling , were at least partially corrected in vivo by nf - b inhibition . this finding provides additional experimental evidence that an increase of nf - b activity plays a causal role in lps - related inflammation . our data show that a diet supplemented with antioxidants prevents nf - b activation in mice treated with lps . it should be noted that several previous studies using similar animal inflammation models demonstrated that pretreatment with antioxidant n - acetylcysteine or n - acetylcysteine combined with - tocopherol before endotoxin administration resulted in a decrease in nf - b activation , lowered tnf - release , and increased survival . in addition , the administration of n - acetylcysteine with vitamin e and - carotene reduced lipid peroxidation and restored gsh levels in endotoxic rats . moreover , it was demonstrated that the genetic reduction of nf - b reduced the amount of mitochondrial - derived ros . in the present study , we hypothesised that an excess of coenzyme q in the diet , along with other fat - soluble vitamins , could be very useful due to the unique properties of ubiquinones as suppressors of cholesterol synthesis , thereby enhancing membrane fluidity . a significant decrease in cholesterol synthesis and a subsequent drop in the cholesterol concentration of the cellular membranesadditionally , the inhibition of cholesterol synthesis in lymphocytes cultivated in vitro with coenzyme q9 was demonstrated . interestingly , our data indicated that the preintervention with dietary antioxidants decreased the magnitude of the inflammatory response , but diet did not amplify the effect of ikk inhibitor xii . these results demonstrating nonadditive anti - inflammatory effects of ikk inhibitor xii and dietary antioxidants suggest antioxidant activity of the studied inhibitor . thus , it can theoretically be assumed that there was a coincidental interaction between the protective mechanisms of the inhibitor and antioxidants , which may both be mediated via the reduction of reactive oxygen species . this assumption is consistent with recent data demonstrating that the inhibition of nf - b activity reduces oxidative stress and damage in vitro and in vivo . thymic peptide thymulin , which is a metallopeptide consisting of a nonapeptide ( glu - ala - lys - ser - gln - gly - gly - ser - asp ) that couples with zinc ions , mostly has inhibitory effects on immune responses and also stimulates endocrine systems , indicating its role in the recovery from inflammatory conditions . using thymulin as an immune - modulator in the second experimental line , we tested a repertoire of cytokines , including il - 6 and il - 17 . although il - 17 was identified more than 15 years ago as a product of cd4 t cells , it was only recently proven that il - 17 is preferentially produced by a subset of t cells , specifically th17 , which have been shown to be very important in the pathogenesis of autoimmune disease . additionally , it has been shown recently that thymulin significantly reduces the disease severity in mice with acute experimental autoimmune encephalomyelitis . il - 17 and il - 6 are important in many disorders characterised by immune self - recognition , and il - 6 is known to induce the differentiation of th17 cells , but the role of th17 cells in septic inflammation is still unclear . we demonstrated that the separate administration of the inhibitor and thymulin or their combination did not significantly change the plasma il - 17 concentration . other cytokines , namely , tnf - alpha and ifn - gamma , were significantly decreased in mice that were pretreated with thymulin , ikk inhibitor xii , or the combination thereof . these data support the assumption that th17 cells do not play an active role in inflammatory pathogenesis induced by lps . the plasma cytokine observations certainly do not provide a complete picture regarding the response to damage . it is possible that the release of cytokines is temporally differentiated , and the extent of release and utilisation seems to be nonsynchronous for different cytokines . indeed , it was reported that after the intravenous administration of endotoxin in humans , plasma il - 6 increased slowly compared with plasma tnf - alpha . alternately , monitoring short - lived signal and stress proteins in the cells enables a more complete evaluation of cellular responses . indeed , inhibition of the ikk / nf - b pathway using ikk inhibitor xii delayed phosphorylation of both independent steps of nf - b signalling , ikk , and p65 . in addition , activation of the sapk / jnk pathway also decreased in cells from lps - plus - inhibitor - treated mice . the results of the present study demonstrate that thymulin enhances the activity of the ikk inhibitor xii . taken together , these results demonstrate that reducing nf - b activity using both thymulin and ikk inhibitor xii decreases the inflammatory response in vivo . the inhibition of nf - b using thymulin plus nf - b inhibitor offers what we believe to be a novel strategy for delaying or attenuating inflammatory diseases in patients with sirs ( systemic inflammatory response syndrome ) or sepsis .\noutput:\n" }, { "from": "agent", "value": "the present study was designed to compare the anti - inflammatory effects of several agents applied in vivo , namely , a synthetic inhibitor of the nf - b cascade , fat - soluble antioxidants , and the thymic peptide thymulin . cytokine response in lps - treated mice was analysed in tandem with the following parameters : the synthesis of inducible forms of the heat shock proteins hsp72 and hsp90 ; activity of the nf - b and sapk / jnk signalling pathways ; and tlr4 expression . inflammation - bearing balb / c male mice were pretreated with an inhibitor of ikk - / kinases ( ikk inhibitor xii ) ; with thymulin ; with dietary coenzyme q9 , - tocopherol , and - carotene ; or with combinations of the inhibitor and peptide or antioxidants . comparable anti - inflammatory effects were observed in inflammation - bearing mice treated separately with thymulin or with dietary antioxidants administered daily for two weeks before lps treatment . when lps - injected mice were treated with the inhibitor and antioxidants together , neither plasma cytokines , signal proteins , nor heat shock proteins recovered more efficiently than when mice were treated with these agents separately . in contrast to antioxidant diet , the thymulin was shown to increase the effect of ikk inhibitor xii in preventing ikk activation in lps - treated mice ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we prospectively enrolled a casual sample of outpatients attending 1 of 12 participating french foot clinics ( supplementary data ) between 1 april 2008 and 30 june 2010 for any type of foot ulcer after informed consent was obtained . patients were included if they had not received any antibiotic agents in the previous week . this study was approved by the local ethics committee ( south mediterranean iii ) and carried out in accordance with the declaration of helsinki as revised in 2000 . every patient was examined by trained physicians to grade infection severity . according to the idsa / iwgdf criteria ( 4,5 ) , wounds were considered either uninfected ( grade 1 ) or infected ( grade 2 ) . after wound debridement , samples for bacterial culture were obtained by swabbing the wound base , needle aspiration , or tissue biopsy and immediately sent to the bacteriology department . only patients with monomicrobial culture for s. aureuspatients with uninfected ulcers did not undergo antibiotic treatment and were monitored closely for 30 days to definitively assess the wound status ( infected vs. uninfected ) . if the wound was considered to be worsening before the follow - up visit , patients were instructed to return to the outpatient facility for early review and a further sample was taken for bacterial culture . at the follow - up visit , if the wound was healing but not completely reepithelialized , a sample for bacterial culture was obtained and the outcome was considered favorable . for completely reepithelialized wounds , no microbiological specimens were sampled and the wound was considered healed . genus , species , and antibiotic susceptibilities were determined using the vitek 2 card ( biomrieux , marcy - letoile , france ) and interpreted according to the recommendations of the french society for microbiology ( 10 ) . susceptibility to methicillin was screened by agar diffusion using cefoxitin disks ( biorad , marnes - la - coquette , france ) ( 10 ) . each s. aureus strain collected during the study was analyzed at the inserm laboratory in nmes , france . the alere staphytype dna microarray was used according to protocols and procedures previously described ( 6,7 ) . the test was able to screen numerous markers simultaneously in 5 h. the dna microarray covers 334 target sequences including the main virulence and resistance genes . dna was extracted from each s. aureus strain , and after amplification and hybridization , markers were identified . a cc may be defined as a cluster of strains ( clones ) that are close enough together to be claimed to share a common origin . this affiliation of isolates was assessed by an automated comparison of hybridization profiles to a collection of reference strains previously characterized ( 6,7,11 ) . in order to determine the ccs of the colonizing strains , we first analyzed the 11 s. aureus strains from clinically uninfected ulcers that we isolated in our previous study ( 8 ) . more information regarding oligonucleotide dna arrays and genotyping can be found in supplementary data . the presence of each gene in s. aureus strains was compared as to ulcer grades and outcome of ulcers using fisher exact test . the most predictive genes for a favorable outcome or healing were expressed by sensitivity , specificity , and positive and negative predictive values ; area under the receiver operating characteristic ( roc ) curve was calculated by the nonparametric hanley method . to assess the usefulness of combining several virulence markers , we used logistic regression with a backward procedure to select the most relevant markers ; only markers for which area under the roc curve was 0.80 were initially entered as explanatory variables in the regression analysis . an roc curve was then generated for the combination of relevant genes derived from the regression model , and its area was compared with that of every single virulence marker by a nonparametric method adapted to paired data ( 12 ) . statistical analysis was performed using the s - plus 2000 software package ( insightful , seattle , wa ) , and results were considered significant for p 0.05 . we prospectively enrolled a casual sample of outpatients attending 1 of 12 participating french foot clinics ( supplementary data ) between 1 april 2008 and 30 june 2010 for any type of foot ulcer after informed consent was obtained . patients were included if they had not received any antibiotic agents in the previous week . this study was approved by the local ethics committee ( south mediterranean iii ) and carried out in accordance with the declaration of helsinki as revised in 2000 . every patient was examined by trained physicians to grade infection severity . according to the idsa / iwgdf criteria ( 4,5 ) , wounds were considered either uninfected ( grade 1 ) or infected ( grade 2 ) . after wound debridement , samples for bacterial culture were obtained by swabbing the wound base , needle aspiration , or tissue biopsy and immediately sent to the bacteriology department . only patients with monomicrobial culture for s. aureuspatients with uninfected ulcers did not undergo antibiotic treatment and were monitored closely for 30 days to definitively assess the wound status ( infected vs. uninfected ) . if the wound was considered to be worsening before the follow - up visit , patients were instructed to return to the outpatient facility for early review and a further sample was taken for bacterial culture . at the follow - up visit , if the wound was healing but not completely reepithelialized , a sample for bacterial culture was obtained and the outcome was considered favorable . for completely reepithelialized wounds , no microbiological specimens were sampled and the wound was considered healed . genus , species , and antibiotic susceptibilities were determined using the vitek 2 card ( biomrieux , marcy - letoile , france ) and interpreted according to the recommendations of the french society for microbiology ( 10 ) . susceptibility to methicillin was screened by agar diffusion using cefoxitin disks ( biorad , marnes - la - coquette , france ) ( 10 ) . each s. aureus strain collected during the study was analyzed at the inserm laboratory in nmes , france . the alere staphytype dna microarray was used according to protocols and procedures previously described ( 6,7 ) . the test was able to screen numerous markers simultaneously in 5 h. the dna microarray covers 334 target sequences including the main virulence and resistance genes . dna was extracted from each s. aureus strain , and after amplification and hybridization , markers were identified . a cc may be defined as a cluster of strains ( clones ) that are close enough together to be claimed to share a common origin . this affiliation of isolates was assessed by an automated comparison of hybridization profiles to a collection of reference strains previously characterized ( 6,7,11 ) . in order to determine the ccs of the colonizing strains , we first analyzed the 11 s. aureus strains from clinically uninfected ulcers that we isolated in our previous study ( 8 ) . more information regarding oligonucleotide dna arrays and genotyping can be found in supplementary data . the presence of each gene in s. aureus strains was compared as to ulcer grades and outcome of ulcers using fisher exact test . the most predictive genes for a favorable outcome or healing were expressed by sensitivity , specificity , and positive and negative predictive values ; area under the receiver operating characteristic ( roc ) curve was calculated by the nonparametric hanley method . to assess the usefulness of combining several virulence markers , we used logistic regression with a backward procedure to select the most relevant markers ; only markers for which area under the roc curve was 0.80 were initially entered as explanatory variables in the regression analysis . an roc curve was then generated for the combination of relevant genes derived from the regression model , and its area was compared with that of every single virulence marker by a nonparametric method adapted to paired data ( 12 ) . statistical analysis was performed using the s - plus 2000 software package ( insightful , seattle , wa ) , and results were considered significant for p 0.05 . during the study period , 195 patients were recruited in whom s. aureus was the sole organism isolated from the bacterial culture of their wound . seventy - five wounds ( 38.5 % ) were classified as uninfected ( grade 1 ) and 120 as infected ( grades 24 ) . as shown in table 1 , both groups were well matched for age , sex , type , and complications of diabetes . at the follow - up visit ,24 of initially uninfected dfus were healed ( 32 % ) and 33 had a favorable outcome ( 44 % ) , whereas 18 ( 24 % ) had worsened rapidly ( 30 days ) . no association was found between the uninfected ulcers that worsened and clinical ( peripheral arterial disease , neuropathy ) or biochemical ( hba1c ) parameters . in each case , an s. aureus strain was isolated from the second bacterial sampling carried out in those uninfected ulcers that were not completely healed at the follow - up visit , regardless of whether the outcome was favorable . overall , there were 246 isolates of s. aureus ( 195 at baseline and 51 at the follow - up ) , of which 40 ( 16.3 % ) were methicillin resistant ( 35 [ 17.9 % ] at baseline and 5 [ 9.8 % ] during the follow - up period ) . demographic and clinical characteristics of study patients cc distribution of isolates allowed comparison between the strains , examination of the biodiversity of the isolates , and determination of their origin and clonality . using the new technology , the ccs of the 11 colonizing s. aureus strains isolated in our previous pilot study ( 8 ) were shown to belong only to two clones , cc8methicillin - sensitive s. aureus ( mssa ) and cc5 - mssa . thus , we hypothesized that these two ccs corresponded to colonizing ccs and other ccs were considered infecting ccs . on admission , 44 strains ( 59 % ) from clinically uninfected wounds belonged to colonizing ccs compared with only 6 ( 5 % ) from infected dfus ( p 0.001 ) . according to the outcomeisolated from dfus whose outcome were favorable were also taken into account ( fig . 1 and table 2 ) . on the other hand , no strains isolated from dfus with a worsening outcome belonged to colonizing ccs and there was no change of ccs between admission and the follow - up visit . infecting ccs were recovered from 96 % of s. aureus isolated from infected ulcers or with a worsening outcome . among these infecting ccs , cc45 - mssa was the most commonly identified in 21 strains . if we used the colonizing ccs to differentiate uninfected from infected ulcers , sensitivity was 0.59 and specificity 0.95 and positive and negative predictive values were 0.88 and 0.79 , respectively . if colonizing ccs were considered for differentiating dfus according to the outcome , diagnostic performances were substantially improved ( table 2 ) . finally , the methicillin - resistant s. aureus ( mrsa ) strains mainly belonged to cc8 - mrsa ( lyon clone ) ( n = 25 strains ) , the main clone present in french hospitals . flow of patients through the study and results of cc8 - mssa / cc5 - mssa obtained of grade 14 inclusion and during follow - up of uninfected ulcers . * grades according to the idsa / iwgdf classification system ( 4,5 ) : grade 2 , n = 38 ; grade 3 , n = 70 ; grade 4 , n = 12 . distribution of colonizing and infecting clonal complexes of s. aureus according to the outcome of dfus the univariate analysis found that among the five genes ( sea , sei , lukde , hlgv , and cap8 ) that we previously identified as predictive for differentiating infected from noninfected dfus ( 8 ) , only two ( lukde and hlgv ) actually distinguished infected from uninfected dfus ( p 0.05 ) ( table 3 ) . however , three of these five genes ( cap8 , lukde , and hlgv ) differentiated s. aureus isolated from uninfected dfus with favorable outcome and s. aureus isolated both from infected and uninfected dfus with a poor outcome ( p 0.05 ) . moreover , the five genes were significantly associated with the wound outcome : cap8 and sei with a poor outcome as opposed to sea , lukde , and hlgv , which were associated with dfus with favorable outcomes ( table 3 ) . in the univariate analysis ,72 additional genes were found to be significantly associated with the outcome of uninfected ulcers ( p 0.05 ) ( data not shown ) . from the logistic model analysis , lukde was the most predictive gene for the favorable outcome of uninfected dfu : sensitivity was 0.965 ( sd 0.025 ) and specificity 0.667 ( 0.063 ) , and positive and negative predictive values were 0.902 and 0.857 , respectively . using this model , only two uninfected ulcers were misclassified as they healed despite the absence of lukde ; interestingly , one ulcer presented a colonizing cc8 strain and the other a strain positive for panton - valentine leukocidin ( pvl ) . conversely , s. aureus from six ulcers with a poor outcome were positive for lukde gene ; however , these strains belonged to infecting ccs . main virulence profiles of s. aureus isolated from uninfected ( grade 1 ) ulcer at initial sampling and follow - up genes encoding pvl and exfoliatin a , b , and d toxins were found in 4 ( 2 % ) , 1 ( 0.5 % ) , 0 ( 0 % ) , and 12 ( 6 % ) of the isolates , respectively . during the study period , 195 patients were recruited in whom s. aureus was the sole organism isolated from the bacterial culture of their wound . seventy - five wounds ( 38.5 % ) were classified as uninfected ( grade 1 ) and 120 as infected ( grades 24 ) . as shown in table 1 , both groups were well matched for age , sex , type , and complications of diabetes . at the follow - up visit ,24 of initially uninfected dfus were healed ( 32 % ) and 33 had a favorable outcome ( 44 % ) , whereas 18 ( 24 % ) had worsened rapidly ( 30 days ) . no association was found between the uninfected ulcers that worsened and clinical ( peripheral arterial disease , neuropathy ) or biochemical ( hba1c ) parameters . in each case , an s. aureus strain was isolated from the second bacterial sampling carried out in those uninfected ulcers that were not completely healed at the follow - up visit , regardless of whether the outcome was favorable . overall , there were 246 isolates of s. aureus ( 195 at baseline and 51 at the follow - up ) , of which 40 ( 16.3 % ) were methicillin resistant ( 35 [ 17.9 % ] at baseline and 5 [ 9.8 % ] during the follow - up period ) . cc distribution of isolates allowed comparison between the strains , examination of the biodiversity of the isolates , and determination of their origin and clonality . using the new technology , the ccs of the 11 colonizing s. aureus strains isolated in our previous pilot study ( 8 ) were shown to belong only to two clones , cc8methicillin - sensitive s. aureus ( mssa ) and cc5 - mssa . thus , we hypothesized that these two ccs corresponded to colonizing ccs and other ccs were considered infecting ccs . on admission , 44 strains ( 59 % ) from clinically uninfected wounds belonged to colonizing ccs compared with only 6 ( 5 % ) from infected dfus ( p 0.001 ) . according to the outcomeisolated from dfus whose outcome were favorable were also taken into account ( fig . 1 and table 2 ) . on the other hand , no strains isolated from dfus with a worsening outcome belonged to colonizing ccs and there was no change of ccs between admission and the follow - up visit . infecting ccs were recovered from 96 % of s. aureus isolated from infected ulcers or with a worsening outcome . among these infecting ccs , cc45 - mssa was the most commonly identified in 21 strains . if we used the colonizing ccs to differentiate uninfected from infected ulcers , sensitivity was 0.59 and specificity 0.95 and positive and negative predictive values were 0.88 and 0.79 , respectively . if colonizing ccs were considered for differentiating dfus according to the outcome , diagnostic performances were substantially improved ( table 2 ) . finally , the methicillin - resistant s. aureus ( mrsa ) strains mainly belonged to cc8 - mrsa ( lyon clone ) ( n = 25 strains ) , the main clone present in french hospitals . flow of patients through the study and results of cc8 - mssa / cc5 - mssa obtained of grade 14 inclusion and during follow - up of uninfected ulcers . * grades according to the idsa / iwgdf classification system ( 4,5 ) : grade 2 , n = 38 ; grade 3 , n = 70 ; grade 4 , n = 12 . distribution of colonizing and infecting clonal complexes of s. aureus according to the outcome of dfusthe univariate analysis found that among the five genes ( sea , sei , lukde , hlgv , and cap8 ) that we previously identified as predictive for differentiating infected from noninfected dfus ( 8 ) , only two ( lukde and hlgv ) actually distinguished infected from uninfected dfus ( p 0.05 ) ( table 3 ) . however , three of these five genes ( cap8 , lukde , and hlgv ) differentiated s. aureus isolated from uninfected dfus with favorable outcome and s. aureus isolated both from infected and uninfected dfus with a poor outcome ( p 0.05 ) . moreover , the five genes were significantly associated with the wound outcome : cap8 and sei with a poor outcome as opposed to sea , lukde , and hlgv , which were associated with dfus with favorable outcomes ( table 3 ) . in the univariate analysis ,72 additional genes were found to be significantly associated with the outcome of uninfected ulcers ( p 0.05 ) ( data not shown ) . from the logistic model analysis , lukde was the most predictive gene for the favorable outcome of uninfected dfu : sensitivity was 0.965 ( sd 0.025 ) and specificity 0.667 ( 0.063 ) , and positive and negative predictive values were 0.902 and 0.857 , respectively . using this model , only two uninfected ulcers were misclassified as they healed despite the absence of lukde ; interestingly , one ulcer presented a colonizing cc8 strain and the other a strain positive for panton - valentine leukocidin ( pvl ) . conversely , s. aureus from six ulcers with a poor outcome were positive for lukde gene ; however , these strains belonged to infecting ccs . main virulence profiles of s. aureus isolated from uninfected ( grade 1 ) ulcer at initial sampling and follow - up genes encoding pvl and exfoliatin a , b , and d toxins were found in 4 ( 2 % ) , 1 ( 0.5 % ) , 0 ( 0 % ) , and 12 ( 6 % ) of the isolates , respectively . over the last few years , various dna array technologies have been developed , but most systems are very expensive , time - consuming , technically demanding , and difficult to adapt to the needs of clinical screening , restricting their use to research laboratories ( 6,7 ) . in contrast , compared with the first generation of miniaturized oligonucleotide array , the new system we used is more convenient and informative . each dna microarray carries a set of 334 different probes ( vs. 50 for the first generation ) , and the use of strip - integrated arrays is time - saving ( 5 h vs. 1 day for the first generation ) , easy to perform and to interpret , and allows a large number of samples to be analyzed ( 96 - well strip ) ( 6,7 ) at low cost ( 60 usd , which is three times less expensive than the first generation ) . moreover , the new arrays allow for assessment of whether the strains are identical by determining the ccs . the main result of our multicenter study is that the microarray technology revealed differences between uninfected and infected ulcers and , if the results are confirmed , the use of this technique may enable clinicians to identify infection and to predict the outcome of apparently clinically uninfected wounds . the most interesting contribution of this new microarray is its ability to determine the clonal ccs of the strains . as a result , a lot of ccs were isolated from dfus ( supplementary data ) , demonstrating that a large panel of s. aureus is involved in this pathology . the results of this study also clearly suggest that the colonizing s. aureus strains belonged to 2 ccs : cc8 - mssa and cc5 - mssa . the distribution of these ccs was significantly different in uninfected and infected dfus ( 58 vs. 5 % , respectively ; p 0.001 ) and predicted a favorable outcome of the uninfected wounds , as 86 % of strains isolated from uninfected ulcers that healed or had a favorable outcome belonged to these ccs . we previously showed that the association of five virulence markers could distinguish uninfected and infected dfus ( 8 ) . the current study shows that a single one of the five markers ( lukde ) may suffice with a high sensitivity ( 96.5 % ) . the association of ccs and the lukde gene is a powerful tool for predicting the wound outcome . for example , none of the six ulcers from which lukde - positive s. aureus was isolated and that had a poor outcome belonged to a colonizing cc . however , the results of the current study vary from those of our previous study : only two ( lukde and hlgv ) of the five previously identified virulence genes actually allowed the distinction between infected and uninfected dfus . moreover , it is worth noting that cap8 gene was a marker of colonization in our pilot study but a marker of worsening evolution in the current study . some explanations may be put forward to account for those discrepancies : the current study is multicentric , and the detection tools are different ( pcr versus arrays with different targets for the same gene ) . moreover , the time between the two studies coincided with a quite marked decrease in the prevalence of mrsa in france ( involving a change in clonal strains ) . interestingly , this study showed that all of the uninfected strains that worsened had the same genotype ( cc and content of 334 genes ) , indicating that the wounds were actually infected and not only colonized . these results highlight the potential usefulness of this technique in patients in whom the clinical diagnosis of infection is made difficult by , for example , peripheral arterial disease , neuropathy , or impaired leukocyte functions ( 13 ) . additionally , the dna microarray might provide important help for clinicians and might allow for adequate management of clinically uninfected ulcers carrying s. aureus , according to its genotype profile . results of the current study raise the question about antibiotic treatment in apparently uninfected dfus and challenge the dogma about abstention of antibiotic therapy in clinically uninfected ulcers ( 14,15 ) . furthermore , this new generation of microarray rapidly gives information about in vitro susceptibility of s. aureus , especially about the presence of meca gene , an important therapeutic concern . worth noting is that that the prevalence of mrsa was low in the current study ( 18 % ) , confirming the decreasing trends in mrsa prevalence in france ( 16 ) . while 14 patients with uninfected ulcers had an mrsa strain at baseline , only five cases of mrsa were recovered during the follow - up , suggesting that debridement of the wound alone may be sufficient for eradicating mrsathe favorable outcome associated with uninfected dfu with s. aureus belonging to the infectingthis clonal complex does not have to be included in colonizing cc , as three dfus were actually infected by cc1 s. aureus . finally , an additional valuable feature of the array technology is its ability to identify pvl genes , since these genes coding for a cytotoxin are claimed to be a major threat in severe tissue necrosis ( 1721 ) . however , these strains are rarely isolated from chronic wounds ( 22,23 ) and their pathogenicity is low in this setting ; accordingly , some pvl strains isolated from grade 1 ulcers were healed 1 month later . this suggests that the portal of entry of pvl strains is not the chronic wound . the dna array represents a powerful tool for predicting the evolution of uninfected ulcer , and a clinical study on the cost - effectiveness of this technology on the healing time and amputation rate would be interesting . one of the main limitations of this study is that it was conducted exclusively on dfus with s. aureus as the sole pathogen , while the flora of dfus is often polymicrobial . nevertheless , if we focus on uninfected ulcers , most of them are monomicrobial , and s. aureus is one of the most frequently isolated microorganisms . s. aureus is also the most common pathogen in infected ulcers , even if the infection is polymicrobial ( 24 ) . moreover , to eliminate any influence of another pathogen in the clinical course of the wounds , it was useful to study wounds with only s. aureus strains . hence , this clinical platform appears suitable for use under routine conditions in a microbiology laboratory . another limitation is that the specimens for culture were not obtained by the same method in all patients . finally , despite the fact that the clinical diagnosis of infection was made by experts in the field , the interobserver variability in diagnosing infected ( vs. uninfected ) dfus was not tested and is largely unknown . in conclusion , as our previous study suggested , the miniaturized oligonucleotide arrays are an interesting tool for managing dfus : they allow an early discrimination between infection and colonization of wounds by s. aureus . some results of this study challenge the current belief that antibiotic therapy is not needed for clinically uninfected dfus . one concern is that this may encourage clinicians to use this technology for screening apparently uninfected ulcers , contrary to current guidelines .\noutput:\n" }, { "from": "agent", "value": "objectiveto extend our previous work on evaluating the use of oligonucleotide arrays to discriminate colonization from infection owing to staphylococcus aureus in diabetic foot ulcers ( dfus ) . research design and methodspatients admitted to 14 french diabetic foot departments for a dfu were screened for entry into the study . at admission , ulcers were classified based on clinical examination according to the infectious diseases society of america system . only patients with monomicrobial culture for s. aureus were included . in persons with an uninfected ulcer , a second wound bacterial specimen was obtained 1 month later . using oligonucleotide arrays , s. aureus resistance and virulence genes were determined , and each isolate was affiliated to a clonal complex ( cc ) . resultss . aureus was initially isolated from 75 uninfected and 120 infected ulcers ; 35 were methicillin resistant . a total of 44 ( 59 % ) strains from uninfected dfus belonged to cc5 / cc8 clones vs. 6 ( 5 % ) from infected dfus ( p < 0.001 ) . during follow - up , 57 ( 76 % ) of uninfected dfus healed or had a favorable outcome ; the strain in 49 ( 86 % ) of them belonged to cc5 / cc8 . conversely , 18 ( 24 % ) had a poor outcome but not a single strain belonged to cc5 / cc8 clone . moreover , lukde was significantly associated with a favorable outcome of the wound.conclusionsas suggested by our previous study , the use of dna arrays appears to be a promising technique that might help distinguishing uninfected from infected wounds , predicting ulcer outcome and then contributing to a more adequate use of antibiotics ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: tramadol hydrochloride is a centrally acting , synthetic , opioid analgesic structurally similar to codeine and morphine . tramadol has proven efficacy and safety in a number of acute painful conditions , including trauma , renal or biliary colic , and labor . chronic pain of malignant or nonmalignant origin , particularly neuropathic pain , is also a common indication for tramadol .1 tramadol is available as drops , tablets , and capsules for oral administration . the mean absolute bioavailability of tramadol with all oral formulations is approximately 70 % , irrespective of concomitant intake of food . the relationship between serum concentrations and the analgesic effect is dose - dependent , but varies considerably in individual cases . a serum concentration of 100300 ng / ml is usually effective .2 the short elimination half - life of 6 hours necessitates dosing of patients with immediate - release ( ir ) tramadol preparations every 46 hours in order to maintain optimal levels of analgesia in chronic pain . the dose of tramadol is titrated upwards as necessary . the maximum recommended dose of tramadol is 400 mg / day .3 successful long - term treatment of patients with painful conditions requires an appropriate dosage form , optimal dosing , and patient compliance . stable serum levels without marked peak to trough fluctuations and reduced frequency of dosing improve patient compliance , patient satisfaction , and , ultimately , quality of life . tramadol 100 mg , 200 mg , and 300 mg sr tablets are available commercially to overcome the difficulties associated with the frequent dosing needed for ir tramadol preparations . in recent years , generic drug products have become very popular . bioequivalence studies are the commonly accepted method to demonstrate therapeutic equivalence between two medicinal products . bioequivalence can be shown either with a single - dose study or a multiple - dose steady - state study . savings in time and cost are substantial when using bioequivalence as an established surrogate marker of therapeutic equivalence . ipca laboratories limited ( mumbai , india ) has developed an sr tablet containing tramadol 200 mg as a generic substitute for the corresponding innovator product . in general , a steady - state study under fasting conditions and two separate single - dose studies under fasting and fed conditions are required to demonstrate bioequivalence for the modified - release dosage forms . therefore , three bioequivalence studies were undertaken to compare the pharmacokinetic properties of tramadol hydrochloride sr tablets 200 mg ( ipca laboratories limited ) and zydol ( tramadol ) sr 200 mg prolonged - release tablets ( grunenthal ltd , high wycombe , uk ) in healthy subjects . two studies were conducted under fasting and fed conditions using a single - dose approach , and a third study was conducted using a steady - state approach under fasting conditions . all of these studies were conducted after confirming the acceptable results of an in vitro comparative dissolution study . a comparative in vitro dissolution study was conducted ahead of the in vivo bioequivalence studies . it was ensured that the in vitro dissolution data were acceptable as per the regulatory guidelines for conducting bioequivalence studies .4 the dissolution study was carried out on 12 units each of the test and reference products using the paddle method as per the british pharmacopoeia monograph . the paddle rotation speed was maintained at 50 rotations per minute at 370.5 c . the test was carried out using 900 ml of ph 6.8 phosphate buffer as a dissolution medium . each sample solution was analyzed by high - performance liquid chromatography to determine the dissolution rate . the mean dissolution values at each time interval were used to calculate the difference factor ( f1 ) and similarity factor ( f2 ) using the standard mathematical equation . in total , 48 , 60 , and 54healthy volunteers were enrolled for the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the ranges for age , weight , and height were 1941 years , 4679 kg , and 149182 cm , respectively . the studies were conducted in accordance with the declaration of helsinki , the international conference on harmonization good clinical practice guidelines , and the note for guidance on the investigation of bioavailability and bioequivalence laid down by the european agency for the evaluation of medicinal products .57 the study protocols were approved by the drushti independent ethics committee , navi mumbai , maharashtra , india . all the studies were conducted using an open - label , randomized , two - treatment , two - period , two - sequence , crossover bioequivalence design . the duration of treatment , including the washout period between the two study periods , was 12 days for both the single - dose studies and 21 days for the multiple - dose study . healthy adult male subjects were enrolled in the study . the sample size ( number of subjects ) was calculated on the assumption that there would not be any interaction between formulations and periods , the observations would be log normally distributed , and the variances of test and reference parameters would be the same . compared with the single - dose fasting studies , the multiple - dose fasting study had more subjects , in anticipation of a higher number of withdrawals due to multiple exposures to the study drugs . similarly , the number of subjects for the single - dose fed study was the highest , considering the additional factor of subjects potential noncompliance with the morning highcalorie high - fat breakfast and subsequent withdrawal from the study . the subjects enrolled were expected to produce a probability of greater than 90 % for concluding bioequivalence within the normal acceptance limits of 80 % 125 % for the pharmacokinetic parameters , at a consumer risk of 5 % . subjects with significant diseases or clinically significant abnormal findings were ruled out during screening by obtaining a complete medical history , performing a full physical examination , and laboratory investigations , including hematology , biochemistry , serology , and urine analysis . the subjects met all the following inclusion criteria and none of the exclusion criteria : male gender , with age range 1855 years , bmi in the range 18.524.9 kg / m normal baseline medical history , physical examination , and vital signs ( blood pressure , pulse rate , respiration rate , and axillary temperature ) normal hematology , biochemistry , infectious disease screening ( human immunodeficiency virus , hepatitis b , and hepatitis c ) , urinalysis , electrocardiography , and x - ray willingness not to use any prescription or over the counter medications , including vitamins and minerals , for 14 days prior to and during the course of the study any medical or surgical condition which might significantly interfere with the functioning of the gastrointestinal tract , blood - forming organs , etc history of cardiovascular , renal , hepatic , ophthalmic , pulmonary , neurologic , metabolic , hematologic , gastrointestinal , endocrine , immunologic , or psychiatric disease participation in a clinical drug study or bioequivalence study 90 days prior to the present study use of xanthine - containing beverages or food ( tea , coffee , chocolate , and cola ) , grapefruit juice , and any alcoholic products for 48 hours prior to dosing until after the last sample collection in each study period blood donation 90 days prior to commencement or during the study known history of hypersensitivity to tramadol hydrochloride or related drugs found positive on urine test for drug abuse done on the day of check - in for each study period history of problems with swallowing tablets . all the enrolled subjects were confined for at least 12 hours prior to drug administration . after a fast of at least 10 hours , oral administration of the test and reference products was done on day 1 for both the single - dose studies and on days 15 for the multiple - dose study in each study period as per the randomization code , with 240 ml of water at ambient temperature . for the single - dose fed study , a high - fat high - calorie breakfast yielding approximately 8001000 calories was given to the subjects half an hour before dosing in each period . a total of 22 blood samples for both the single - dose studies and 26 blood samples for the multiple - dose study were collected from the subjects during each study period . blood samples were collected predose and at 12 hours postdose on days 1 , 2 , 3 , and 4 by fresh venepuncture in the multiple - dose study . serial blood samples were collected for pharmacokinetic evaluation on day 1 for the single - dose studies and on day 5 for the multiple - dose study until 48 hours postdosing in each period . after collection , the blood samples were centrifuged at 53c and 3500 rotations per minute for 10 minutes to obtain plasma . all plasma samples were stored in the upright position at 205c until analysis of the samples . the supervising medical officers or nursing staff measured vital signs under the supervision of the principal investigator . vital signs ( blood pressure , pulse rate , respiratory rate , and temperature ) were measured before check - in , predosing , after dosing at prescheduled times , and on discontinuation from the study . the subjects were monitored for any adverse events and / or complaints throughout the study . at the end of the study , poststudy evaluation , including physical examination , vital signs , 12 - lead electrocardiogram , and clinical laboratory tests ( hemogram , biochemistry , and urinalysis ) the subjects plasma samples were analyzed at the bioanalytical facility of accutest research laboratories ( i ) private limited . samples from periods 1 and 2 for each subject were analyzed together for all the studies . the investigators analyzing the samples did not have access to the randomization schedule and hence were blinded to the order of administration of the study medication . for all the studies , the analytical method validation included 0.2 ml of plasma samples and solid - phase extraction . the linearity range was 7.550759.994 ng / ml and 1.006148.710 ng / ml for tramadol and its m1 metabolite , respectively . the linearity range was enough to quantify the expected concentration range of drug from subject s plasma with the proposed dose of tramadol . all the statistical analyses were performed using sas software ( v. 9.1 ; sas institute , cary , nc ) . as per the requirements for single - dose and steady - state studies , the following parameters were calculated individually for each subject from their tramadol and m1 metabolite plasma concentrations : auc ( area under the plasma concentration - time curve in ng * hr / ml calculated by the linear trapezoidal method ) ; auc tau ( auc measured throughout the dosing interval at steady state ) ; cmax ( maximum plasma concentration observed , in ng / ml ) ; cmaxss ( cmax observed at steady state , in ng / ml ) ; cminss ( minimum plasma concentration observed at steady state , in ng / ml ) ; cpd ( predose concentration determined immediately before drug was given at steady state ) ; cavg ( computed as auctau / tau where tau is dosing interval in hours = 24 ) ; % ptf ( peaktrough fluctuation calculated as 100 ( cmaxss cminss ) / cavg ) ; and swing ( [ cmaxss cminss ] / cminss ) . tramadol and its m1 metabolite were considered for establishing bioequivalence between the test and reference products . the pharmacokinetic parameters auc and cmax for the single - dose studies and auctau , cmaxss , and cminss for the multiple - dose study were taken as primary efficacy variables . all values below the limit of quantification were considered as zero for the computation of pharmacokinetic parameters and statistical calculations .05 ) on the log - transformed primary pharmacokinetic parameters , auc , cmax for the single - dose studies , and auctau , cmaxss , and cminss for the multiple - dose study . effects of period , treatment , and sequence on primary efficacy criteria were analyzed by anova . each anova also included calculation of least - square means , adjusted differences between formulation means , and the standard error associated with these differences . the 90 % confidence intervals for the ratio of geometric means were calculated for the log - transformed primary pharmacokinetic parameters . the confidence interval was expressed as a percentage relative to the least - square means of the reference treatments . bioequivalence was to be concluded when 90 % confidence intervals were within the acceptable range of 80 % 125 % for log - transformed primary pharmacokinetic parameters . a comparative in vitro dissolution study was conducted ahead of the in vivo bioequivalence studies . it was ensured that the in vitro dissolution data were acceptable as per the regulatory guidelines for conducting bioequivalence studies .4 the dissolution study was carried out on 12 units each of the test and reference products using the paddle method as per the british pharmacopoeia monograph . the paddle rotation speed was maintained at 50 rotations per minute at 370.5 c . the test was carried out using 900 ml of ph 6.8 phosphate buffer as a dissolution medium . each sample solution was analyzed by high - performance liquid chromatography to determine the dissolution rate . the mean dissolution values at each time interval were used to calculate the difference factor ( f1 ) and similarity factor ( f2 ) using the standard mathematical equation . in total , 48 , 60 , and 54 healthy volunteers were enrolled for the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the ranges for age , weight , and height were 1941 years , 4679 kg , and 149182 cm , respectively . the studies were conducted in accordance with the declaration of helsinki , the international conference on harmonization good clinical practice guidelines , and the note for guidance on the investigation of bioavailability and bioequivalence laid down by the european agency for the evaluation of medicinal products .57 the study protocols were approved by the drushti independent ethics committee , navi mumbai , maharashtra , india . all the studies were conducted using an open - label , randomized , two - treatment , two - period , two - sequence , crossover bioequivalence design . the duration of treatment , including the washout period between the two study periods , was 12 days for both the single - dose studies and 21 days for the multiple - dose study . healthy adult male subjects were enrolled in the study . the sample size ( number of subjects ) was calculated on the assumption that there would not be any interaction between formulations and periods , the observations would be log normally distributed , and the variances of test and reference parameters would be the same . compared with the single - dose fasting studies , the multiple - dose fasting study had more subjects , in anticipation of a higher number of withdrawals due to multiple exposures to the study drugs . similarly , the number of subjects for the single - dose fed study was the highest , considering the additional factor of subjects potential noncompliance with the morning highcalorie high - fat breakfast and subsequent withdrawal from the study . the subjects enrolled were expected to produce a probability of greater than 90 % for concluding bioequivalence within the normal acceptance limits of 80 % 125 % for the pharmacokinetic parameters , at a consumer risk of 5 % . subjects with significant diseases or clinically significant abnormal findings were ruled out during screening by obtaining a complete medical history , performing a full physical examination , and laboratory investigations , including hematology , biochemistry , serology , and urine analysis . male gender , with age range 1855 years , bmi in the range 18.524.9 kg / m normal baseline medical history , physical examination , and vital signs ( blood pressure , pulse rate , respiration rate , and axillary temperature ) normal hematology , biochemistry , infectious disease screening ( human immunodeficiency virus , hepatitis b , and hepatitis c ) , urinalysis , electrocardiography , and x - ray willingness not to use any prescription or over the counter medications , including vitamins and minerals , for 14 days prior to and during the course of the studyany medical or surgical condition which might significantly interfere with the functioning of the gastrointestinal tract , blood - forming organs , etc history of cardiovascular , renal , hepatic , ophthalmic , pulmonary , neurologic , metabolic , hematologic , gastrointestinal , endocrine , immunologic , or psychiatric disease participation in a clinical drug study or bioequivalence study 90 days prior to the present study use of xanthine - containing beverages or food ( tea , coffee , chocolate , and cola ) , grapefruit juice , and any alcoholic products for 48 hours prior to dosing until after the last sample collection in each study period blood donation 90 days prior to commencement or during the study known history of hypersensitivity to tramadol hydrochloride or related drugs found positive on urine test for drug abuse done on the day of check - in for each study period history of problems with swallowing tablets . all the enrolled subjects were confined for at least 12 hours prior to drug administration . after a fast of at least 10 hours , oral administration of the test and reference productswas done on day 1 for both the single - dose studies and on days 15 for the multiple - dose study in each study period as per the randomization code , with 240 ml of water at ambient temperature . for the single - dose fed study , a high - fat high - calorie breakfast yielding approximately 8001000 calories was given to the subjects half an hour before dosing in each period . a total of 22 blood samples for both the single - dose studies and 26 blood samples for the multiple - dose study were collected from the subjects during each study period . blood samples were collected predose and at 12 hours postdose on days 1 , 2 , 3 , and 4 by fresh venepuncture in the multiple - dose study . serial blood samples were collected for pharmacokinetic evaluation on day 1 for the single - dose studies and on day 5 for the multiple - dose study until 48 hours postdosing in each period . after collection , the blood samples were centrifuged at 53c and 3500 rotations per minute for 10 minutes to obtain plasma . all plasma samples were stored in the upright position at 205c until analysis of the samples . the supervising medical officers or nursing staff measured vital signs under the supervision of the principal investigator . vital signs ( blood pressure , pulse rate , respiratory rate , and temperature ) were measured before check - in , predosing , after dosing at prescheduled times , and on discontinuation from the study . the subjects were monitored for any adverse events and / or complaints throughout the study . at the end of the study , poststudy evaluation , including physical examination , vital signs , 12 - lead electrocardiogram , and clinical laboratory tests ( hemogram , biochemistry , and urinalysis ) were performed . the subjects plasma samples were analyzed at the bioanalytical facility of accutest research laboratories ( i ) private limited . samples from periods 1 and 2 for each subject were analyzed together for all the studies . the investigators analyzing the samples did not have access to the randomization schedule and hence were blinded to the order of administration of the study medication . for all the studies , the analytical method validation included 0.2 ml of plasma samples and solid - phase extraction . the linearity range was 7.550759.994 ng / ml and 1.006148.710 ng / ml for tramadol and its m1 metabolite , respectively . the linearity range was enough to quantify the expected concentration range of drug from subject s plasma with the proposed dose of tramadol . all the statistical analyses were performed using sas software ( v. 9.1 ; sas institute , cary , nc ) . as per the requirements for single - dose and steady - state studies , the following parameters were calculated individually for each subject from their tramadol and m1 metabolite plasma concentrations : auc ( area under the plasma concentration - time curve in ng * hr / ml calculated by the linear trapezoidal method ) ; auc tau ( auc measured throughout the dosing interval at steady state ) ; cmax ( maximum plasma concentration observed , in ng / ml ) ; cmaxss ( cmax observed at steady state , in ng / ml ) ; cminss ( minimum plasma concentration observed at steady state , in ng / ml ) ; cpd ( predose concentration determined immediately before drug was given at steady state ) ; cavg ( computed as auctau / tau where tau is dosing interval in hours = 24 ) ; % ptf ( peaktrough fluctuation calculated as 100 ( cmaxss cminss ) / cavg ) ; and swing ( [ cmaxss cminss ] / cminss ) . tramadol and its m1 metabolite were considered for establishing bioequivalence between the test and reference products . the pharmacokinetic parameters auc and cmax for the single - dose studies and auctau , cmaxss , and cminss for the multiple - dose study were taken as primary efficacy variables . all values below the limit of quantification were considered as zero for the computation of pharmacokinetic parameters and statistical calculations .05 ) on the log - transformed primary pharmacokinetic parameters , auc , cmax for the single - dose studies , and auctau , cmaxss , and cminss for the multiple - dose study . effects of period , treatment , and sequence on primary efficacy criteria were analyzed by anova . each anova also included calculation of least - square means , adjusted differences between formulation means , and the standard error associated with these differences . the 90 % confidence intervals for the ratio of geometric means were calculated for the log - transformed primary pharmacokinetic parameters . the confidence interval was expressed as a percentage relative to the least - square means of the reference treatments . bioequivalence was to be concluded when 90 % confidence intervals were within the acceptable range of 80 % 125 % for log - transformed primary pharmacokinetic parameters . the difference factor ( f1 ) of 1.39 ( acceptable limit 015 ) and the similarity factor ( f2 ) of 88.07 ( acceptable limit 50100 ) were obtained . a comparative in vitro dissolution study provides a basis for predicting the likelihood of achieving a successful in vivo bioequivalence performance . this in vitro dissolution study showed that the test and reference products were comparable , indicating essential similarity of both the formulations . the subjects completing both the study periods successfully were considered for pharmacokinetic and statistical analysis of both tramadol and its m1 metabolite . tramadol was rapidly absorbed after oral administration , with mean peak plasma levels achieved at approximately 45 hours postdose for the test as well as reference products in all the studies ( tables 1 and 2 , figure 2 ) . the m1 metabolite was rapidly absorbed after oral administration , with mean peak plasma levels achieved at approximately 78 hours postdose for the test and reference products in all the studies ( tables 1 and 2 , figure 3 ) . the rate and extent of absorption , as evident from the cmax and auc0t values for tramadol and its m1 metabolite , was higher for the fed state than for the fasting state ( table 1 ) . in summary , the pharmacokinetic data obtained in all our studies were in accordance with the published data .13,8 in the multiple - dose steady - state study , it was observed that the mean peak - trough fluctuation for tramadol was 151.75 % for the test product and 133.55 % for the reference product . corresponding values for the m1 metabolite were 104.11 % and 93.18 % for the test and reference products , respectively ( table 2 ) . we observed the mean peak - trough fluctuations in plasma tramadol concentrations to be significantly higher than those reported in the literature . grond and sablotzki reported a fluctuation in tramadol concentrations of approximately 66 % with the sr tramadol formulation at steady state .1 karhu and bouchard noted this to be 56 % 96 % .8 the occurrence of high mean peak - trough fluctuations in our multiple - dose study could be due to insufficient frequency of drug administration . in all the published studies , the dosing frequency was as per the labeling of the innovator product . in the multiple - dose study , twice - daily administration of the tramadol sr tablet was an ideal way to reach steady state , with less fluctuation . however , once - daily administration of tramadol probably resulted in wide fluctuation in this study . overall , the intrasubject variability observed for both the analytes in our studies was low . the highest variability was 13.64 % , observed for the cminss with tramadol in our multipledose study . as mentioned in the literature , wide variability in the pharmacokinetic parameters of tramadol , which could be partly due to polymorphism in cytochrome p450 isoforms , was not observed in the present studies .1 the subjects in our studies probably did not have any genetic polymorphisms to account for marked pharmacokinetic variability . it was observed that the ratios for geometric least - square means and 90 % confidence intervals were within the acceptance criteria of 80 % 125 % for log - transformed primary pharmacokinetic parameters for tramadol and its m1 metabolite in all the studies ( table 3 ) . a significant period effect for the cmax of tramadol and its m1 metabolite was observed in both the single - dose studies . however , this can be ignored because it was not coupled with any sequence effect . a significant treatment effect for cmaxss and cminss for tramadol and cminss for the m1 metabolite was observed in the multiple - dose study . this effect might reflect the difference in the formulations , but it did not seem to have any impact on the study outcome because the confidence intervals for the log - transformed pharmacokinetic parameters fell within the acceptance range . , 48 , 60 , and 54 subjects were exposed to either of the treatments in period 1 of the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively , while the corresponding numbers were 48 , 46 , and 37 in period 2 . successful completion of the clinical phase was done by 40 , 44 , and 35 subjects in the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the highest occurrence of adverse events was observed in the multiple - dose fasting study . in this study , a total of 187 adverse events were reported , of which 103 events were observed in subjects given the test product and 84 events were observed in those given the reference product ( table 4 ) . occurrence of an adverse event was the underlying cause for withdrawal of 8 , 14 , and 16 subjects in the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the poststudy laboratory evaluation did not reveal any clinically significant observations requiring further intervention in all the studies . dizziness , pruritus , headache , and vomiting were the most common adverse events for both the study treatments , as reported by other investigators .1,9 our results are consistent with the published data . the greater occurrence of adverse events in the multiple - dose fasting study could be due to the higher number of exposures of the subjects to the study drugs , with a relatively high dose of tramadol . however , we did not observe any correlation between the occurrence of adverse events and peaking of plasma tramadol concentrations in either of the studies . all the adverse events were mild to moderate in severity , and resolved during the clinical phase . the difference factor ( f1 ) of 1.39 ( acceptable limit 015 ) and the similarity factor ( f2 ) of 88.07 ( acceptable limit 50100 ) were obtained . a comparative in vitro dissolution study provides a basis for predicting the likelihood of achieving a successful in vivo bioequivalence performance . this in vitro dissolution study showed that the test and reference products were comparable , indicating essential similarity of both the formulations . the subjects completing both the study periods successfully were considered for pharmacokinetic and statistical analysis of both tramadol and its m1 metabolite . tramadol was rapidly absorbed after oral administration , with mean peak plasma levels achieved at approximately 45 hours postdose for the test as well as reference products in all the studies ( tables 1 and 2 , figure 2 ) . the m1 metabolite was rapidly absorbed after oral administration , with mean peak plasma levels achieved at approximately 78 hours postdose for the test and reference products in all the studies ( tables 1 and 2 , figure 3 ) . the rate and extent of absorption , as evident from the cmax and auc0t values for tramadol and its m1 metabolite , was higher for the fed state than for the fasting state ( table 1 ) . in summary , the pharmacokinetic data obtained in all our studies were in accordance with the published data .13,8 in the multiple - dose steady - state study , it was observed that the mean peak - trough fluctuation for tramadol was 151.75 % for the test product and 133.55 % for the reference product . corresponding values for the m1 metabolite were 104.11 % and 93.18 % for the test and reference products , respectively ( table 2 ) . we observed the mean peak - trough fluctuations in plasma tramadol concentrations to be significantly higher than those reported in the literature . grond and sablotzki reported a fluctuation in tramadol concentrations of approximately 66 % with the sr tramadol formulation at steady state .1 karhu and bouchard noted this to be 56 % 96 % .8 the occurrence of high mean peak - trough fluctuations in our multiple - dose study could be due to insufficient frequency of drug administration . in all the published studies , the dosing frequency was as per the labeling of the innovator product . in the multiple - dose study , twice - daily administration of the tramadol sr tablet was an ideal way to reach steady state , with less fluctuation . however , once - daily administration of tramadol probably resulted in wide fluctuation in this study . overall , the intrasubject variability observed for both the analytes in our studies was low . the highest variability was 13.64 % , observed for the cminss with tramadol in our multipledose study . as mentioned in the literature , wide variability in the pharmacokinetic parameters of tramadol , which could be partly due to polymorphism in cytochrome p450 isoforms , was not observed in the present studies .1 the subjects in our studies probably did not have any genetic polymorphisms to account for marked pharmacokinetic variability . it was observed that the ratios for geometric least - square means and 90 % confidence intervals were within the acceptance criteria of 80 % 125 % for log - transformed primary pharmacokinetic parameters for tramadol and its m1 metabolite in all the studies ( table 3 ) . a significant period effect for the cmax of tramadol and its m1 metabolite was observed in both the single - dose studies . however , this can be ignored because it was not coupled with any sequence effect . a significant treatment effect for cmaxss and cminss for tramadol and cminss for the m1 metabolite was observed in the multiple - dose study . this effect might reflect the difference in the formulations , but it did not seem to have any impact on the study outcome because the confidence intervals for the log - transformed pharmacokinetic parameters fell within the acceptance range . in total , 48 , 60 , and 54 subjects were exposed to either of the treatments in period 1 of the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively , while the corresponding numbers were 48 , 46 , and 37 in period 2 . successful completion of the clinical phase was done by 40 , 44 , and 35 subjects in the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the highest occurrence of adverse events was observed in the multiple - dose fasting study . in this study , a total of 187 adverse events were reported , of which 103 events were observed in subjects given the test product and 84 events were observed in those given the reference product ( table 4 ) . occurrence of an adverse event was the underlying cause for withdrawal of 8 , 14 , and 16 subjects in the single - dose fasting , single - dose fed , and multiple - dose fasting studies , respectively . the poststudy laboratory evaluation did not reveal any clinically significant observations requiring further intervention in all the studies . dizziness , pruritus , headache , and vomiting were the most common adverse events for both the study treatments , as reported by other investigators .1,9 our results are consistent with the published data . the greater occurrence of adverse events in the multiple - dose fasting study could be due to the higher number of exposures of the subjects to the study drugs , with a relatively high dose of tramadol . however , we did not observe any correlation between the occurrence of adverse events and peaking of plasma tramadol concentrations in either of the studies . all the adverse events were mild to moderate in severity , and resolved during the clinical phase . the in vitro dissolution study indicated suitability of the test product for use in the in vivo bioequivalence studies . all of the in vivo studies in healthy human subjects demonstrated that the generic test tablet , tramadol hydrochloride sr 200 mg , is bioequivalent to the reference product , zydol sr 200 mg , in terms of rate and extent of absorption . the highest number of adverse events and dropouts / withdrawals was observed in the multiple - dose fasting study . the longer study duration , multiple drug administration , and relatively high total dose of tramadol probably contributed to the findings of this study .\noutput:\n" }, { "from": "agent", "value": "backgroundtramadol hydrochloride is available as 50 mg immediate - release ( ir ) and 100 mg , 200 mg , and 300 mg sustained - release ( sr ) tablets . the recommended dose of tramadol is 50100 mg ir tablets every 46 hours . the tramadol sr 200 mg tablet is a better therapeutic option , with a reduced frequency of dosing , and improved patient compliance and quality of life . the present study evaluated the bioequivalence of a generic tramadol sr 200 mg tablet.methodsa comparative in vitro dissolution study was performed on the test and reference products , followed by two separate single - dose bioequivalence studies under fasting and fed conditions and one multiple - dose bioequivalence study under fasting conditions . these bioequivalence studies were conducted in healthy human subjects using an open - label , randomized , two - treatment , two - period , two - sequence , crossover design . the oral administration of the test and reference products was done on day 1 for both the single - dose studies and on days 15 for the multiple - dose study in each study period as per the randomization code . serial blood samples were collected at predefined time points in all the studies . analysis of plasma concentrations of tramadol and o - desmethyltramadol ( the m1 metabolite ) was done by a validated liquid chromatography - mass spectrometry analytical method . the standard acceptance criterion of bioequivalence was applied on log - transformed pharmacokinetic parameters for tramadol and its m1 metabolite.resultsthe ratios for geometric least - square means and 90 % confidence intervals were within the acceptance range of 80 % 125 % for log - transformed primary pharmacokinetic parameters for tramadol and its m1 metabolite in all the three studies.conclusionthe test product is bioequivalent to the reference product in terms of rate and extent of absorption , as evident from the single - dose and multiple - dose studies . both the treatments were well tolerated ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: cystolic aldehyde dehydrogenase ( aldh1a1 ) has been associated with alcohol - induced flushing in caucasians , and alcohol sensitivity and dependence , and functions in the detoxification of acetaldehyde , the first metabolite of ethanol oxidation . additionally , aldh1a1 is involved in the degradation of dopamine ( da ) in the ventral tegmental area ( vta ) . this role in the regulation of da degradation may be important in the development and maintenance of excessive alcohol consumption because vta da function can be ethanol induced via increased da neurone firing , and the vta lies within the mesolimbic system , which functions in reward , motivation and various substance disorders , including alcohol dependence . association between genetic variation in aldh1a1 ( on chromosome 9q21 .13 ) and inter - individual differences in the vulnerability to alcohol dependence and other alcohol - related phenotypes has been investigated in several studies . while there are three alternative splice patterns producing two aldh1a1 isoforms , aldh1a1two promoter polymorphisms have recently been correlated with the development of alcohol dependence in south - west californian indians and other populations . spence and colleagues sequenced the aldh1a1 promoter region in asian , caucasian and african - american alcoholics and control subjects . they discovered two rare promoter polymorphisms , aldh1a1 * 2 and aldh1a1 * 3 ( only detected in african americans ) . while no association was observed between aldh1a1 * 2 and alcohol dependence , there was a nominally significant difference in aldh1a1 * 3 allelic frequency between alcoholics ( 6 per cent ) and controls ( 0 ) , and the aldh1a1 * 3 polymorphism resulted in reduced aldh1a1 expression . ehlers et al . replicated this study in a south - west californian indian population of alcoholics and controls and observed a protective role for the aldh1a1 * 2 polymorphism , whereby individuals with an aldh1a1 * 2 allele reported lower rates of alcohol dependence , drank fewer drinks per session and reported a lower maximum number of drinks consumed in a 24 - hour period . conversely , the aldh1a1 * 2 alleles were later reported to be associated with increased development of alcohol dependency in indo - trinidadians . two other studies have reported genetic linkage in the 9q21 region with phenotypic measures of alcohol consumption in predominantly caucasian american samples from the framingham heart study ( fhs ) . bergen et al . observed nominally significant evidence of linkage in the 9q21 .11 region between three loci and a square - root - transformed ' maximum alcohol consumed in a 24 - hour period ' variable , maxapd . stronger evidence for linkage of maxapd on chromosome 9 was detected by ma et al . with a maximal logarithm of the odds ratio ( lod ) score of 2.27 in the region of aldh1a1 . due to the recently established role of aldh1a1 in alcohol - related phenotypes and the dual function of aldh1a1 in both the alcohol and da metabolism pathways , we screened eight polymorphisms across the 52.8 - kilobase ( kb ) aldh1a1 gene for association with alcohol consumption patterns and alcohol dependence in our finnish population . alcohol dependence and problem drinking were determined by alcoholism treatment status and the alcohol use disorder identification test ( audit ) , a measure of alcohol consumption behaviour . the finnish subjects ( with finnish ethnicity ) consisted of 104 men enlisted during clinical treatment for alcoholism and a sample of 201 male volunteers from the general population ( including alcohol - dependent and control subjects ) , either recruited through advertisements ( n = 129 ) or drawn from the finnish population register ( n = 72 ) by the national public health institute of helsinki , finland . blood was obtained from all subjects and total genomic dna was extracted using the puregenedna isolation kit ( gentra , inc . , minneapolis , mn , usa ) according to the manufacturer 's instructions . hazardous or harmful alcohol consumption behaviour and alcohol - related problems were assessed by the audit . this instrument consists of ten items , which , when responded to in the affirmative , increase the likelihood that the subject is alcohol dependent . the questionnaire measures alcohol intake ( quantity and frequency ; items 1 - 3 ) , dependence symptoms ( items 4 - 6 ) and alcohol - related problems ( items 7 - 10 ) . all items are equally weighted and scored between 0 and 4 and the completed audit is scored by summing the values for each item . the interpretation of the audit , with respect to alcohol use disorders , has been well validated and reviewed by a number of groups [ 12 - 15 ] . distinguished between hazardous and harmful drinking , whereby hazardous alcohol intake is indicative of an increased risk of harmful consequences for the user or others , and harmful alcohol use is defined as consumption behaviour that has resulted in physical or psychological damage . additionally , babor and colleagues recommend further evaluation for alcohol dependence for those who score 20 or higher . accordingly , our study population was subdivided into four groups based upon total audit score and history of alcohol dependence treatment : ( 1 ) control drinkers scored 12 on the audit but were not alcohol nave ( n = 105 ) ; ( 2 ) hazardous drinkers scored 13 - 19 on the audit ( excluded from further genetic analyses , n = 32 ) ; ( 3 ) problem drinkers had an audit score 20 ( n = 64 ) ; and ( 4 ) treated alcoholics were recruited from alcohol treatment facilities ( n = 104 ) . since genotype data were not available from the international hapmap project public database at the time this study was conceived ( july 2003 ) , eight single nucleotide polymorphisms ( snps ) in or near the adlh1a1 locus were selected from the applied biosystems snp database . snps were initially chosen to be evenly distributed across adlh1a1 , including one snp in both the 5 ' and 3 ' untranslated regions ( utrs ) , with an average inter - marker spacing of 10.7 kb . ( abi ; foster city , ca , usa ) . to ensure quality control , dna samples from cases and controlseach 5 l experiment contained 25 ng genomic dna , 1.6 x taqman assay primer / probe mix , 1x pcr buffer a , 2.5 mm mgcl2 , 250 m deoxyribonucleotide triphosphates ( dntps ) and 0.5 u amplitaq gold polymerase . thermocycling was performed as recommended by abi using a dual 384 - well geneamppcr system 9700 cycler and cycling conditions as follows : an initial denaturation stage at 95c for 12 minutes , then 40 cycles of 95c for 15 seconds and 60c for one minute , followed by storage at 4c in the dark . genotypes were determined on an abi 7900ht fast real - time pcr system using the allelic discrimination mode . all polymorphisms were first assessed to determine if the observed genotype frequencies were consistent with hardy - weinberg proportions using pearson chi - square tests within stata ( version 8.1 ; stata corporation , college station , tx , usa ) . pair - wise marker - marker linkage disequilibrium ( ld ) was assessed in haploview ( version 4.0 ) . to test for association between each snp and the continuously distributed ' audit score ' , we performed analysis of variance models ( anova ) using proc glm within the sas software system ( version 8.0 ; sas institute , cary , nc , usa ) . genotype was first tested for general association ( no mode of inheritance assumption ) using a two - degrees of freedom f - test . further testing of the snp effects assuming genetic modes of inheritance for that snp were then performed . for dominant or recessive genetic transmission models , a single indicator variable ( eg idom is an indicator variable taking the value 1 ifan individual has genotype 1/2 or 2/2 , and 0 otherwise ) was used . a variable taking the values -1 for genotype 1/1 ; 0 for genotype 1/2 ; and 1 for genotype 2/2 was used to test for additive genetic effects . in addition , odds ratios ( or ) and 95 per cent wald confidence intervals ( 95 per cent ci ) were estimated in stata 8.1 for both the allelic and genotypic distribution by dividing the dataset into controls ( n = 105 , audit score 12 ) , problem drinkers ( n = 64 , audit score 20 ) and treated alcoholics ( n = 104 ) . genotype and allele distributions for the problem drinkers and treated alcoholic subjects were each compared with those in the controls as the reference group . genotypic odds ratios were calculated by collapsing two genotypes ( one heterozygous and one homozygous group ) into one , and comparing the collapsed genotype count with that of the count of the remaining homozygous genotype . alcohol use disorder identification test ( audit ) response , mean and standard deviation per item , in the finnish control drinkers , problem drinkers and treated alcohol - dependent groups , based on audit score and / or alcohol treatment status all audit items , except questions 9 and 10 , are confined to previous year . the finnish population consists of alcoholic subjects recruited from alcohol treatment facilities ( n = 104 ) and volunteer subjects from the general population that includes control drinkers ( n = 105 ) , hazardous drinkers ( n = 32 ) and problem drinkers , as defined by the audit ( n = 64 ) . control drinkers had an audit score 12 and had consumed alcohol in the previous year . problem drinkers have an audit score 20 but were not recruited from alcohol treatment facilities . an audit score 12 indicates a pattern of hazardous consumption , while an audit score 20 suggests that the subject is alcohol dependent . to test for haplotypic association between the markers and audit score , a generalised linear model for the quantitative trait ' audit score ' qtphase is part of the unphased suite of programs for association analysis of multilocus haplotypes ( an expectation - maximisation [ e - m ] algorithm is used to deal with uncertain haplotypes ) from unphased genotype data . all chi - square statistics and p - values are presented without correction for multiple testing . a schematic representation of the human aldh1a1 gene structure and linkage disequilibrium ( ld ) . the gene structure of aldh1a1 is shown with exons numbered and relative exon size denoted by the width of the vertical bars . the eight snps analysed in this study are shown in relation to their location across aldh1a1 and regions of low to high pair - wise ld , as measured by the rstatistic , are represented by light grey to black shading , respectively . the finnish subjects ( with finnish ethnicity ) consisted of 104 men enlisted during clinical treatment for alcoholism and a sample of 201 male volunteers from the general population ( including alcohol - dependent and control subjects ) , either recruited through advertisements ( n = 129 ) or drawn from the finnish population register ( n = 72 ) by the national public health institute of helsinki , finland . blood was obtained from all subjects and total genomic dna was extracted using the puregenedna isolation kit ( gentra , inc . , minneapolis , mn , usa ) according to the manufacturer 's instructions . hazardous or harmful alcohol consumption behaviour and alcohol - related problems were assessed by the audit . this instrument consists of ten items , which , when responded to in the affirmative , increase the likelihood that the subject is alcohol dependent . the questionnaire measures alcohol intake ( quantity and frequency ; items 1 - 3 ) , dependence symptoms ( items 4 - 6 ) and alcohol - related problems ( items 7 - 10 ) . all items are equally weighted and scored between 0 and 4 and the completed audit is scored by summing the values for each item . the interpretation of the audit , with respect to alcohol use disorders , has been well validated and reviewed by a number of groups [ 12 - 15 ] . distinguished between hazardous and harmful drinking , whereby hazardous alcohol intake is indicative of an increased risk of harmful consequences for the user or others , and harmful alcohol use is defined as consumption behaviour that has resulted in physical or psychological damage . additionally , babor and colleagues recommend further evaluation for alcohol dependence for those who score 20 or higher . accordingly , our study population was subdivided into four groups based upon total audit score and history of alcohol dependence treatment : ( 1 ) control drinkers scored 12 on the audit but were not alcohol nave ( n = 105 ) ; ( 2 ) hazardous drinkers scored 13 - 19 on the audit ( excluded from further genetic analyses , n = 32 ) ; ( 3 ) problem drinkers had an audit score 20 ( n = 64 ) ; and ( 4 ) treated alcoholics were recruited from alcohol treatment facilities ( n = 104 ) . since genotype data were not available from the international hapmap project public database at the time this study was conceived ( july 2003 ) , eight single nucleotide polymorphisms ( snps ) in or near the adlh1a1 locus were selected from the applied biosystems snp database . snps were initially chosen to be evenly distributed across adlh1a1 , including one snp in both the 5 ' and 3 ' untranslated regions ( utrs ) , with an average inter - marker spacing of 10.7 kb . ( abi ; foster city , ca , usa ) . to ensure quality control , dna samples from cases and controlseach 5 l experiment contained 25 ng genomic dna , 1.6 x taqman assay primer / probe mix , 1x pcr buffer a , 2.5 mm mgcl2 , 250 m deoxyribonucleotide triphosphates ( dntps ) and 0.5 u amplitaq gold polymerase . thermocycling was performed as recommended by abi using a dual 384 - well geneamppcr system 9700 cycler and cycling conditions as follows : an initial denaturation stage at 95c for 12 minutes , then 40 cycles of 95c for 15 seconds and 60c for one minute , followed by storage at 4c in the dark . genotypes were determined on an abi 7900ht fast real - time pcr system using the allelic discrimination mode . all polymorphisms were first assessed to determine if the observed genotype frequencies were consistent with hardy - weinberg proportions using pearson chi - square tests within stata ( version 8.1 ; stata corporation , college station , tx , usa ) . pair - wise marker - marker linkage disequilibrium ( ld ) was assessed in haploview ( version 4.0 ) . to test for association between each snp and the continuously distributed ' audit score ' , we performed analysis of variance models ( anova ) using proc glm within the sas software system ( version 8.0 ; sas institute , cary , nc , usa ) . genotype was first tested for general association ( no mode of inheritance assumption ) using a two - degrees of freedom f - test . further testing of the snp effects assuming genetic modes of inheritance for that snp were then performed . for dominant or recessive genetic transmission models , a single indicator variable ( eg idom is an indicator variable taking the value 1 ifan individual has genotype 1/2 or 2/2 , and 0 otherwise ) was used . a variable taking the values -1 for genotype 1/1 ; 0 for genotype 1/2 ; and 1 for genotype 2 / 2in addition , odds ratios ( or ) and 95 per cent wald confidence intervals ( 95 per cent ci ) were estimated in stata 8.1 for both the allelic and genotypic distribution by dividing the dataset into controls ( n = 105 , audit score 12 ) , problem drinkers ( n = 64 , audit score 20 ) and treated alcoholics ( n = 104 ) . genotype and allele distributions for the problem drinkers and treated alcoholic subjects were each compared with those in the controls as the reference group . genotypic odds ratios were calculated by collapsing two genotypes ( one heterozygous and one homozygous group ) into one , and comparing the collapsed genotype count with that of the count of the remaining homozygous genotype . alcohol use disorder identification test ( audit ) response , mean and standard deviation per item , in the finnish control drinkers , problem drinkers and treated alcohol - dependent groups , based on audit score and / or alcohol treatment status all audit items , except questions 9 and 10 , are confined to previous year . the finnish population consists of alcoholic subjects recruited from alcohol treatment facilities ( n = 104 ) and volunteer subjects from the general population that includes control drinkers ( n = 105 ) , hazardous drinkers ( n = 32 ) and problem drinkers , as defined by the audit ( n = 64 ) . control drinkers had an audit score 12 and had consumed alcohol in the previous year . problem drinkers have an audit score 20 but were not recruited from alcohol treatment facilities . an audit score 12 indicates a pattern of hazardous consumption , while an audit score 20 suggests that the subject is alcohol dependent . to test for haplotypic association between the markers and audit score , a generalised linear model for the quantitative trait ' audit score ' qtphase is part of the unphased suite of programs for association analysis of multilocus haplotypes ( an expectation - maximisation [ e - m ] algorithm is used to deal with uncertain haplotypes ) from unphased genotype data . all chi - square statistics and p - values are presented without correction for multiple testing . a schematic representation of the human aldh1a1 gene structure and linkage disequilibrium ( ld ) . the gene structure of aldh1a1 is shown with exons numbered and relative exon size denoted by the width of the vertical bars . the eight snps analysed in this study are shown in relation to their location across aldh1a1 and regions of low to high pair - wise ld , as measured by the rstatistic , are represented by light grey to black shading , respectively . the mean age of the study population was 45.111.1 years , ranging from 21 to 75 years . while the average age of the treated alcoholics ( 44.3 years ) , problem drinkers ( 47.5 years ) and control groups ( 44.2 years ) at the time of interview did not differ significantly ( p 0.05 ) , the average weight ( kg , p = 0.026 ) but not body mass index ( kg / m , p = 0.19 ) of the treated alcoholics ( 77.6 kg , 24.7 kg / m ) and control ( 81.3 kg , 25.3 kg / m ) groups did . among the general population ( n = 201 ) , 15.9 per cent displayed hazardous patterns of alcohol consumption and 31.8 per cent scored 20 on the audit and were classified in our analyses as problem drinkers ( since they generally experienced both dependence symptoms and alcohol - related problems ) and were also included in the problem / dependent group . the problem drinkers and treated alcoholics had marked differences ( p 0.0001 ) in their mean responses for all ten audit items compared with the controls ( table 1 ) . although all groups tended to consume alcoholic beverages on a weekly basis ( item 1 ; 55 per cent of controls and an average of 77 per cent for the problem and dependent drinkers ) , the majority ( 82 per cent ) of problem drinkers and treated subjects consumed an average of six or more drinks per session ( item 2 ) compared with 13 per cent of controls ( on average , the control group imbibed three or four drinks per session ) . this trend was similar for the frequency with which subjects consumed six or more drinks per session ( item 3 ) . while these significant differences in alcohol consumption behaviour ( items 1 - 3 ) were observed between the control and problem / treated groups , an unambiguous distinction from the controls was seen with respect to those items related to dependence symptoms ( items 4 - 6 ) and alcohol - related problems ( items 7 - 10 ) . for these seven items , the mean response was 0.5 and 2.2 for controls and problem / treated groups , respectively , which on a ' occurs on a monthly or more ' basis represents an affirmative response by 2 per cent and 63 per cent of the respective group subjects . association analysis of eight cystolic aldehyde dehydrogenase ( aldh1a1 ) polymorphisms with audit score abbreviations : audit , alcohol use disorder identification test ; maf , minor allele frequency . minor allele frequency of the italicised allele in the volunteers from the general population ( n = 201 ) . genotypic audit score means were calculated in sas ( sas institute , version 8.0 , cary , nc ) using a general test of association . probability for general association between each snp and the audit score using analysis of variance models . lowest probability of association assuming a genetic mode of inheritance ( given in table ) with respect to allele 2 . genotypic and allelic analysis of the aldh1a1 rs348479 , rs6l0529 and rs348449 polymorphisms in finnish controls , problem drinkers and clinically treated alcoholic subjects the population ( n = 305 ) snp allele frequencies are as follows : rs348479 g allele frequency = 0.17 , rs610529 g allele frequency = 0.37 and rs348449 g allele frequency = 0.03 . the three groups are : ( 1 ) controls ( audit score 12 ) ; ( 2 ) problem drinkers ( audit score 20 , not treated for alcoholism ) ; and ( 3 ) clinically treated alcoholics . genotype and allele distributions of the problem drinkers andtreated alcoholic subjects were each compared with those in the control group using two - sided pearson 's chi - square or fisher exact tests , respectively . odds ratios ( or ) and wald 95 % confidence intervals ( 95 % ci ) were determined separately for the allele and genotype counts of problem drinkers and treated alcoholic subjects versus control drinkers . genotype odds ratios for each snp were calculated as follows : rs348479 ( gg versus [ gt and tt ] ) , rs6l0529 ( [ aa and ag ] versus gg ) and rs348449 ( aa versus [ ag and gg ] ) . abbreviations : maf , minor allele frequency ; n / a , not applicable ; ref , reference group . plot of minus log of p - value for qtphase single - point and sliding window haplotype analysis of association between eight aldh1a1 snps and the audit score , a quantitative measure of alcohol consumption behaviour . the physical locations of the eight snps across the aldh1a1 gene are schematically presented in figure 1 . frequencies of the aldh1a1 genotypes were in general in hardy - weinberg equilibrium ( hwe ) , except for rs595958 in intron 1 ( p = 0.0008 ) , and are listed in table 2 . minor allele frequencies within the control sample were similar to those observed in the centre d'etude du polymorphisme humain ( ceph ) sample ( data not shown ) of the international hapmap project . ld was strongest between markers rs610529 ( intron 8 ) and rs13959 ( exon 3 ) , with one haplotype block structure detected by haploview between these snps . the effective number of independent snps was 6.0 , as determined by single nucleotide polymorphism spectral decomposition ( snpspd ) . we observed nominally significant differences between the genotypic and / or allelic frequencies and mean audit scores for three ( rs348479 in the 3 ' utr , rs610529 in intron 8 and rs348449 in intron 2 ) of the eight snps genotyped in aldh1a1 . the genotypic distribution and allelic frequencies of the three snps are presented in table 3 . the rs348479 t allele was more frequent in subjects with higher audit scores , where the mean audit scores observed for the rs348479 g and t alleles were 17.8 and 19.7 , respectively ( table 2 ) and the frequency of the t allele was 82 per cent in controls compared with 85 per cent ( table 3 ) in the treated alcoholic drinkers . in the analysis of the entire sample ( n = 305 ) , the association of the t allele with the audit score approached nominal significance ( p = 0.08 for general association ) and the estimated genotypic audit score means were suggestive of a dominant genetic model ( p = 0.025 ) with respect to the t allele , where the audit score is highest in those individuals with one or two copies of the t allele compared with individuals with two copies of the g allele ( mean audit score of 11.0 , 19.5 and 19.3 with zero , one and two rs348479 t alleles , respectively ) . the rs348479 genotypic frequencies were significantly different between the controls and treated alcoholics ( p = 0.019 ) ; however , case - control odds ratio calculations did not indicate significant allele frequency differences between the controls and treated alcoholics ( table 3 ) . furthermore , the absence of significant allelic and genotypic differences between the controls and problem drinkers may indicate that rs348479 is involved in risk for alcohol dependence rather than increased or problem alcohol consumption . nonetheless , the results of this study should also be interpreted in the context of multiple testing , since , correcting for the number of independent snps alone , a bonferroni - corrected p - value of 0.0083 ( 0.05 / 6 ) would be required for an association to be declared significant . the rs610529 polymorphism in intron 8 was associated ( p = 0.027 and p = 0.013 for the general and best model of association , which is based upon a recessive mode of inheritance for the g allele ) with the audit score . the genotypic audit score means were 20.5 , 19.1 and 14.7 for zero , one and two rs610529 g alleles , respectively ( table 2 ) . although there were no significant differences in allelic frequencies between control and problem drinkers ( or = 0.92 , 95 per cent ci 0.58 - 1.44 ) , treated alcoholics were approximately 1.5 times less likely to have the g allele ( or = 0.65 , 95 per cent ci 0.43 - 0.98 ) and three times more likely to be either a homozygous aa or a heterozygous ag ( or = 0.32 , 95 per cent ci 0.12 - 0.84 ) ( table 3 ) . as with rs348479 , these analyses provide some evidence for an association between rs6105249 and risk for alcohol dependence rather than problematic alcohol consumption behaviour . the rs348449 polymorphism was nominally associated ( p = 0.043 for the dominant model of inheritance ; p = 0.13 for general association ) where the audit score genotypic means were 18.9 , 24.4 and 22.0 for zero , one and two g alleles , respectively ( table 2 ) . significant differences in both the rs348449 genotypic and allelic frequencies were detected between the controls and the problem drinkers ( table 3 ) . the frequency of the minor allele g was 1 per cent in controls compared with 7 per cent in the problem drinkers and 3.4 per cent in treated alcoholics . problem drinkers were 7.8 times more likely to have the rs348449 g allele ( or = 7.87 , 95 per cent ci 1.67 - 37.01 , p = 0.003 ) and 7.4 times more likely to have the gg or ga genotype ( p = 0.017 ) . by contrast , the allelic and genotypic distributions in the treated alcoholics and control groups were not significantly different . therefore , rs348449 may play a role in the consumption of high levels of alcohol ( which can lead to dependence symptoms and alcohol - related problems ) rather than the development of alcohol dependence . since the age of the control subjects ranged between 24 and 69 years , it is possible that a subset of the younger controls could develop alcohol dependence later in life . therefore , we divided the controls into an older cohort , aged over 40 years ( n = 66 ) , and repeated the allelic and genotypic analyses . with each snp , we observed the same direction of , and similar levels of , association ( data not shown ) . two - and three - locus haplotypic association between aldh1a1 snp genotypes and the quantitative audit score is graphically presented in figure 2 . using qtphase and a sliding window approach , the significance of association increased from p = 0.014 for the single rs610529 snp analysis to 0.0015 ( likelihood ratio statistic [ lrs ] = 15.47 , degrees of freedom [ df ] = 3 ) for rs610529 - rs2288087 haplotype analysis , where the two snps are in high ld ( d ' = 0.97 , r = 0.60 ) . three common haplotypes ( 1 per cent frequency ) were observed , totalling 99.4 per cent of the observed haplotypes . two common haplotypes , ' 1 - 1 ' ( 10.4 per cent frequency ) and ' 1 - 2 ' ( 35.9 per cent frequency ) had mean audit scores of 23.42 ( = 8.37 , p = 0.0038 ) and 17.64 ( = 7.3 , p = 0.0070 ) , respectively . the third common haplotype ( ' 2 - 1 ' , 53.1 per cent ) was not significantly associated ( = 0.4 , p = 0.55 ) with the audit score ( mean score = 19.59 ) . the addition of a third neighbouring snp , rs13959 , did not increase the strength of association ( p = 0.0024 ) . previous linkage and association studies of alcohol consumption or dependence measures have implicated the aldh1a1 gene . although the majority of alcohol studies related to the aldehyde dehydrogenase family focus on aldh2 , particularly in asian populations , recent studies are shining light on the role that aldh1a1 may play in several human alcohol - related traits . in the present study , we analysed eight snps located across aldh1a1 ( including one snp in both the 50 and 30 utrs ) for an association with alcohol dependence status ( using case - control methodology ) and the quantitative audit score in our male finnish population . a 1992 study of finnish drinking habits that utilised the audit questionnaire determined that 22 per cent of males ( 26 per cent of men aged 30 - 49 ) who completed the audit displayed hazardous alcohol consumption ( alcohol consumption indicative of an increased risk of harmful consequences for the user or others ) and 42 per cent usually drank seven or more units of alcohol per session ( item 2 ) , and concluded that in the finnish culture there was an intoxication - seeking nature to alcohol consumption . in 2000 , the 12 - month prevalence of alcohol dependence and alcohol use disorders in a representative sample of male finnish adults ( 30 years ) were 6.5 per cent and 7.3 per cent , respectively . in this study , 15.9 per cent of subjects that were not recruited from alcoholism treatment facilities had experienced hazardous or harmful alcohol consumption in the previous year ( audit score of 12 - 19 ) , which is similar to the findings of holmila , while 31.8 per cent were categorised as problem drinkers ( audit score 20 ) . it should be noted , however , that alcohol - dependent and control drinkers were both specifically recruited in the advertisement campaign and , therefore , the problem - drinking group may have contained a percentage of alcohol - dependent individuals . our findings suggest that both alcohol consumption behaviour and alcohol dependence status are influenced by genetic variation in aldh1a1 . the results from anova analyses demonstrate that two intronic snps ( rs610529 and rs348449 ) and one 3 ' utr snp ( rs348479 ) in aldh1a1 are nominally ( p = 0.01 - 0.04 ) associated with alcohol consumption behaviour , as described by the audit ( table 2 ) . while rs348479 and rs610529 are associated with risk of alcohol dependence rather than problem drinking , rs348449 in intron 2 influences harmful alcohol consumption behaviour that leads to alcohol - related problems and alcohol dependence symptoms ( as determined by odds ratio and contingency analyses of allele and genotype frequencies in control and problem drinkers ) . although the allelic and genotypic distribution of rs348449 was not significantly different between controls and treated alcohol - dependent subjects , it may play a role in alcohol dependence . if babor et al . are correct in their assertion that an audit score 20 indicates alcohol dependence , rs348449 may be associated with the transition from harmful alcohol consumption to alcohol dependence : the mean audit scores were 19.2 and 24.2 for the a and g alleles , respectively , and on average a subject 's audit score increased from 18.8 to 24.4 and 22.0 with zero , one and two g alleles , respectively . additionally , finns with a g allele were 5.2-fold more likely to have been treated for alcohol dependence or have scored 20 on the audit . we have reservations with respect to the validity of the observed associations between this snp and the two alcohol - related phenotypes , however ; the low minor allele frequency ( maf ) in the three drinking groups ( 1 - 7 per cent ) and the absence of g / g homozygotes among the control and treated alcohol dependent drinkers means that there is a high risk of false - positive finding with this snp . the three snps that demonstrated association with alcohol consumption behaviour in this study have not previously been reported in the literature and their functionality is unclear ; they are neither coding snps nor are they near alternative splice sites . nonetheless , we believe that at the genotypic and / or allelic level , each snp may influence transitions in drinking patterns and behaviour in our population , particularly the progression from problem to alcohol - dependent drinker . for example , the genotypic audit score means of the 3 ' utr snp , rs348479 , are 11.00 ( these subjects are classified as control drinkers ) and 19.33 ( bordering between harmful and problem drinkers ) for g / g and t / t homozygotes , respectively . furthermore , the three snps are in moderate ld ( d ' = 0.4 - 0.6 ) , so it may be possible that the snps are in strong ld with an as yet ungenotyped polymorphism that is causal with respect to these alcohol - related phenotypes . an important question , with regard to the relevance of the present data , is the functionality of these polymorphisms ; this needs to be settled in future studies . in conclusion , while the associations detected in the present study are not significant after taking into account multiple testing , multiple studies reporting associations between aldh1a1 and alcohol - related phenotypes have been published recently , and our results provide further evidence for a role of aldh1a1 in the risk for problem alcohol consumption behaviour and possibly alcohol dependence . with this in mind , our findings need to be replicated in a larger finnish or caucasian population and a systematic search for , and genotyping of , additional aldh1a1 variants that influence alcohol - related phenotypes is warranted . the authors wish to thank mrs hilkka salohalla , mrs tuula mkel and mrs lolan lindroos for their excellent technical assistance . this study was supported in part by funds provided by the state of california for medical research on alcohol and substance abuse through the university of california , san francisco .\noutput:\n" }, { "from": "agent", "value": "liver cystolic aldehyde dehydrogenase 1 ( aldh1a1 ) has been previously associated with both alcohol dependence and alcohol consumption behaviour , and has been implicated in alcohol - induced flushing and alcohol sensitivity in caucasians . the present study tested for association between aldh1a1 and alcohol consumption behaviour and susceptibility to problem drinking or alcohol dependence in finnish cohorts of unrelated male subjects recruited from alcoholism clinical treatment facilities ( n = 104 ) and from the general population ( n = 201 ) . all participants completed the alcohol use disorder identification test ( audit ) and were genotyped for eight single nucleotide polymorphisms ( snps ) within or flanking aldh1a1 . to test for association between alcohol consumption behaviour and these polymorphisms , we used generalised linear models and haplotypic analysis . three snps were nominally associated ( rs348449 , p = 0.043 ; rs610529 , p = 0.013 ; rs348479 , p = 0.025 ) with the quantitative audit score , which evaluates alcohol consumption behaviour . two - locus ( rs6i0529 - rs2288087 ) haplotype analysis increased the strength of association with audit score ( p = 0.00 i5 ) . additionally , rs348449 is highly associated with problem drinking ( allelic odds ratio [ or ] 7.87 , 95 per cent confidence interval [ ci ] 1.67 - 37.01 ) but due to the low minor allele frequency ( 0.01 and 0.07 in controls and problem drinkers , respectively ) , more samples are required to validate this observation . conversely , rs348479 ( p = 0.019 ) and rs6i0529 ( allelic or 0.65 , 95 per cent ci 0.43 - 0.98 ; genotypic or 0.32 , 95 per cent ci 0.12 - 0.84 ) are implicated in alcohol dependence status . this study provides further evidence for a role for aldh1a1 in alcohol consumption behaviour , including problem drinking and possibly alcohol dependence , in our finnish population ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the most important factor determining prognosis for these patients is axillary lymph node status . assessment of nodal status currently requires surgery , by performing a sentinel node procedure , followed by an axillary dissection in case of a positive sentinel node . this procedure can cause morbidity and therefore , less invasive staging procedures , such as by imaging , are warranted . diffusion weighted mri ( dwi ) has shown promise in the detection of lymph nodes , but so far can not accurately discriminate benign from malignant nodes . with the use of ultra - small particles of iron oxide ( uspios ) , mri has shown to be able to assess axillary nodal status in vivo with a high positive and negative predictive value . however , this contrast - agent has not been approved for clinical application yet , and identification of metastatic lymph nodes , based solely on morphological criteria , remains challenging . recently , mri systems with a magnetic field strength of 7 tesla ( t ) have come into use . we have used a whole body 7 t mri platform to determine morphological and quantitative characteristics , such as t1 , t2 , t2 * and apparent diffusion coefficients ( adc ) , ex vivo of healthy human axillary lymph nodes . knowledge of benign lymph node characteristics may support a better assessment of metastatic nodes in vivo in the future . mri data was correlated to the gold standard , pathology , on a node to node basis . during two autopsies , four axillary lymph node dissection ( alnd ) specimens were retrieved . the deceased were two females who died of cardiovascular disease and who had donated their bodies to science . an alnd is a block of fatty tissue in which the axillary lymph nodes are located ; nodal configuration and peri - nodal anatomy is thus maintained . subsequently , the specimens were stitched onto a plastic grid and were fixed in formaldehyde for at least 1 week ( range 1 week - 11 weeks ) . the specimens were examined using a commercial 7 t mri system ( philips healthcare , cleveland , usa ) , using a transmit / receive head coil with a 16 channel receive coil ( nova medical , wilmington , ma , usa ) . during mr data acquisition , the specimens were submersed in fomblin ( solvay solexis , bollate , italy ) to provide susceptibility matching . the mr - protocol for all alnds ( 51 nodes ) consisted of : a 3d t1 weighted ( 3d t1w ) fat - suppressed fast field echo [ tr / te 158/4 .8 ms , flip angle 35 , fov 23.6110110 mm , acquired resolution 180 m isotropic ] ( acquisition time ; 5 h and 10 min ) , a t1 - map which was obtained with a 2d look - locker sequence [ tr between inversions 4,000 ms , tr / te 7.6 / 3.7 ms , flip angle 3 , fov 110110 mm , in - plane acquired resolution 500500 m , slice thickness 5 mm , 100 samples with an initial ti of 18 ms and increments of 40 ms per sample ] ( acquisition time 35 min ) . a 3d t1 weighted ( 3d t1w ) fat - suppressed fast field echo [ tr / te 158/4 .8 ms , flip angle 35 , fov 23.6110110 mm , acquired resolution 180 m isotropic ] ( acquisition time ; 5 h and 10 min ) , a t1 - map which was obtained with a 2d look - locker sequence [ tr between inversions 4,000 ms , tr / te 7.6 / 3.7 ms , flip angle 3 , fov 110110 mm , in - plane acquired resolution 500500 m , slice thickness 5 mm , 100 samples with an initial ti of 18 ms and increments of 40 ms per sample ] ( acquisition time 35 min ) . for alnd 3 and 4 ( 34 nodes ) the following quantitative data sets were also acquired : a multi - slice t2 - map which was obtained from a multi - echo spin echo sequence [ tr / first te / te 800 / 6/6 ms , 15 echoes , fov 24110110 mm , resolution 500 m isotropic ] ( acquisition time 5 h and 42 min ) , a multi - slice t2 * - map which was obtained from a multi - echo gradient echo sequence [ tr / first te / te 300/5 .9 / 5.9 ms , 10 echoes , flip angle 35 , fov 24110110 mm , resolution 350 m isotropic ] ( acquisition time 2 h and 47 min ) , a multi - slice diffusion weighted image [ tr / te 4000/83 ms , fov 24110110 mm , resolution 1.0 mm isotropic , b - values 0 , 750 and 1,500 s / mm ] ( acquisition time 2 h and 18 min ) . a multi - slice t2 - map which was obtained from a multi - echo spin echo sequence [ tr / first te / te 800 / 6/6 ms , 15 echoes , fov 24110110 mm , resolution 500 m isotropic ] ( acquisition time 5 h and 42 min ) , a multi - slice t2 * - map which was obtained from a multi - echo gradient echo sequence [ tr / first te / te 300/5 .9 / 5.9 ms , 10 echoes , flip angle 35 , fov 24110110 mm , resolution 350 m isotropic ] ( acquisition time 2 h and 47 min ) , a multi - slice diffusion weighted image [ tr / te 4000/83 ms , fov 24110110 mm , resolution 1.0 mm isotropic , b - values 0 , 750 and 1,500 s / mm ] ( acquisition time 2 h and 18 min ) . pathological examination was performed according to standard alnd protocol by an experienced pathologist , who was blinded to the mri results during the initial evaluation of the specimen . detected nodes were sliced into 4 mm sections and were paraffin embedded after which 3 m thick slices were cut from each 4 mm block , which were subsequently stained with haematoxylin & eosin ( h & e ) . following standard pathological examination , the alnd specimen was correlated to the mri - based map to identify any remaining nodes . after removal of any remaining mri - detected nodes , the residual fatty tissue was submersed in acetone to detect any small lymph nodes which might have been overlooked . for matching purposes with mri , digital pictures of all sectionswere obtained at a 1.5 magnification with a digital camera ( leica , rijswijk , the netherlands ) mounted on top of a standard microscope ( leica ) . after positioning on the plastic grid , a detailed map was drawn of each specimen , noting the location of the individual nodes as they were situated in the fatty alnd tissue , using the horizontal and vertical lines of the grid as longitude and latitude references . after removal of each node , it was dyed to permanently mark the sides which were superior and left on the mr images . the high resolution 3d t1w protocol ( voxel volume 5.8 nanoliter ) allowed reconstruction along arbitrary planes which enabled accurate matching of the mr images to the sectioning plane of microscopic pathology slides . quantitative and morphologic mri analysis was done using in - house software created in matlab ( mathworks , usa ) . quantitative analysis of t2 and t2 * relaxation times and the adcs were determined . values were determined by drawing rois on the transversal views of the fitted maps derived from the original images . the t1 values were calculated according to a t1 - mapping acquisition method described by hsu et al . . the hsu algorithm was selected after testing it on our samples against a 3 parameter non - linear least - squares algorithm which fitted the data directly to the look - locker equation . the hsu - method correlated better to gold standard mr spectroscopy t1 measurements performed on the same specimens ( data not shown ) . for t2 - mapping only the even echo timeswere used to minimize the sensitivity to errors in the pulse angle of the 180 degrees refocusing pulses . in addition to the measured t1 values , temperature - corrected t1 values are presented , which were calculated according to rieke et al . , who described an increase in t1 values of approximately 1.5 % per degree celsius . similarly , adc measured at room temperature , was extrapolated to body temperature , assuming a linear relationship , according to the stokes - einstein equation . the longest diameter ( length ) and the perpendicular in - plane diameter ( width ) were measured on transversal images . the shape , presence of a fatty centre and detailed structural architecture of the nodes were described . a correlation of the size and the morphologic features was performed using spearman s rank test . during two autopsies , four axillary lymph node dissection ( alnd ) specimens were retrieved . the deceased were two females who died of cardiovascular disease and who had donated their bodies to science . an alnd is a block of fatty tissue in which the axillary lymph nodes are located ; nodal configuration and peri - nodal anatomy is thus maintained . subsequently , the specimens were stitched onto a plastic grid and were fixed in formaldehyde for at least 1 week ( range 1 week - 11 weeks ) . the specimens were examined using a commercial 7 t mri system ( philips healthcare , cleveland , usa ) , using a transmit / receive head coil with a 16 channel receive coil ( nova medical , wilmington , ma , usa ) . during mr data acquisition , the specimens were submersed in fomblin ( solvay solexis , bollate , italy ) to provide susceptibility matching . the mr - protocol for all alnds ( 51 nodes ) consisted of : a 3d t1 weighted ( 3d t1w ) fat - suppressed fast field echo [ tr / te 158/4 .8 ms , flip angle 35 , fov 23.6110110 mm , acquired resolution 180 m isotropic ] ( acquisition time ; 5 h and 10 min ) , a t1 - map which was obtained with a 2d look - locker sequence [ tr between inversions 4,000 ms , tr / te 7.6 / 3.7 ms , flip angle 3 , fov 110110 mm , in - plane acquired resolution 500500 m , slice thickness 5 mm , 100 samples with an initial ti of 18 ms and increments of 40 ms per sample ] ( acquisition time 35 min ) . a 3d t1 weighted ( 3d t1w ) fat - suppressed fast field echo [ tr / te 158/4 .8 ms , flip angle 35 , fov 23.6110110 mm , acquired resolution 180 m isotropic ] ( acquisition time ; 5 h and 10 min ) , a t1 - map which was obtained with a 2d look - locker sequence [ tr between inversions 4,000 ms , tr / te 7.6 / 3.7 ms , flip angle 3 , fov 110110 mm , in - plane acquired resolution 500500 m , slice thickness 5 mm , 100 samples with an initial ti of 18 ms and increments of 40 ms per sample ] ( acquisition time 35 min ) . for alnd 3 and 4 ( 34 nodes ) the following quantitative data sets were also acquired : a multi - slice t2 - map which was obtained from a multi - echo spin echo sequence [ tr / first te / te 800 / 6/6 ms , 15 echoes , fov 24110110 mm , resolution 500 m isotropic ] ( acquisition time 5 h and 42 min ) , a multi - slice t2 * - map which was obtained from a multi - echo gradient echo sequence [ tr / first te / te 300/5 .9 / 5.9 ms , 10 echoes , flip angle 35 , fov 24110110 mm , resolution 350 m isotropic ] ( acquisition time 2 h and 47 min ) , a multi - slice diffusion weighted image [ tr / te 4000/83 ms , fov 24110110 mm , resolution 1.0 mm isotropic , b - values 0 , 750 and 1,500 s / mm ] ( acquisition time 2 h and 18 min ) . a multi - slice t2 - map which was obtained from a multi - echo spin echo sequence [ tr / first te / te 800 / 6/6 ms , 15 echoes , fov 24110110 mm , resolution 500 m isotropic ] ( acquisition time 5 h and 42 min ) , a multi - slice t2 * - map which was obtained from a multi - echo gradient echo sequence [ tr / first te / te 300/5 .9 / 5.9 ms , 10 echoes , flip angle 35 , fov 24110110 mm , resolution 350 m isotropic ] ( acquisition time 2 h and 47 min ) , a multi - slice diffusion weighted image [ tr / te 4000/83 ms , fov 24110110 mm , resolution 1.0 mm isotropic , b - values 0 , 750 and 1,500 s / mm ] ( acquisition time 2 h and 18 min ) . pathological examination was performed according to standard alnd protocol by an experienced pathologist , who was blinded to the mri results during the initial evaluation of the specimen . detected nodes were sliced into 4 mm sections and were paraffin embedded after which 3 m thick slices were cut from each 4 mm block , which were subsequently stained with haematoxylin & eosin ( h & e ) . following standard pathological examination , the alnd specimen was correlated to the mri - based map to identify any remaining nodes . after removal of any remaining mri - detected nodes , the residual fatty tissue was submersed in acetone to detect any small lymph nodes which might have been overlooked . for matching purposes with mri , digital pictures of all sectionswere obtained at a 1.5 magnification with a digital camera ( leica , rijswijk , the netherlands ) mounted on top of a standard microscope ( leica ) . after positioning on the plastic grid , a detailed map was drawn of each specimen , noting the location of the individual nodes as they were situated in the fatty alnd tissue , using the horizontal and vertical lines of the grid as longitude and latitude references . after removal of each node , it was dyed to permanently mark the sides which were superior and left on the mr images . the high resolution 3d t1w protocol ( voxel volume 5.8 nanoliter ) allowed reconstruction along arbitrary planes which enabled accurate matching of the mr images to the sectioning plane of microscopic pathology slides . quantitative and morphologic mri analysis was done using in - house software created in matlab ( mathworks , usa ) . values were determined by drawing rois on the transversal views of the fitted maps derived from the original images . the t1 values were calculated according to a t1 - mapping acquisition method described by hsu et al . . the hsu algorithm was selected after testing it on our samples against a 3 parameter non - linear least - squares algorithm which fitted the data directly to the look - locker equation . the hsu - method correlated better to gold standard mr spectroscopy t1 measurements performed on the same specimens ( data not shown ) . for t2 - mapping only the even echo timeswere used to minimize the sensitivity to errors in the pulse angle of the 180 degrees refocusing pulses . in addition to the measured t1 values , temperature - corrected t1 values are presented , which were calculated according to rieke et al . , who described an increase in t1 values of approximately 1.5 % per degree celsius . similarly , adc measured at room temperature , was extrapolated to body temperature , assuming a linear relationship , according to the stokes - einstein equation . the longest diameter ( length ) and the perpendicular in - plane diameter ( width ) were measured on transversal images . the shape , presence of a fatty centre and detailed structural architecture of the nodes were described . a correlation of the size and the morphologic features was performed using spearman s rank test . figure 1 shows a maximum intensity projection of the 3d t1w data set of specimen 2 . forty - two of 51 nodes ( 82 % ) were retrieved during routine dissection of the alnds . of the remaining nine mri - detected nodes , three could be retrieved on reexamination of the specimen ; one directly after consulting the mri - based map and two others after defatting the specimen with acetone . the remaining six mri - detected nodes - all smaller than 32 mm - were not found at pathological examination .1 thin - slab maximum intensity projection over 2 mm of a 3d t1w mr data set ( 180 m isotropic resolution ) of an axillary lymph node dissection specimen . solid white arrows : lymph nodes depicted against a black background consisting of suppressed fat . arrowhead : an artifact caused by a gauze , which had not been drenched in fomblin . rectangle : a remnant of formaldehyde inside the pleats of the specimen thin - slab maximum intensity projection over 2 mm of a 3d t1w mr data set ( 180 m isotropic resolution ) of an axillary lymph node dissection specimen . solid white arrows : lymph nodes depicted against a black background consisting of suppressed fat . arrowhead : an artifact caused by a gauze , which had not been drenched in fomblin . rectangle : a remnant of formaldehyde inside the pleats of the specimen table 1 shows the number of nodes detected by mri and by pathology and the various mri characteristics per alnd . the influence of conservation time on t1 , t2 and t2 * is shown in fig . 2 . table 1lymph node characteristics depicted per axillary lymph node dissection ( alnd ) alnd 1alnd 2alnd 3alnd4all alnds # of nodes at mri98151951 # of nodes at pathology98121645length ( sd ) [ range ] mm11 ( 6 ) [ 2.719.1 ] 10 ( 7 ) [ 1.321.6 ] 9 ( 8 ) [ 2.127.2 ] 9 ( 7 ) [ 3.024.1 ] 9 ( 7 ) [ 1.327.2 ] width ( sd ) [ range ] mm7 ( 5 ) [ 1.913.2 ] 7 ( 6 ) [ 0.615.8 ] 6 ( 5 ) [ 1.317.0 ] 5 ( 4 ) [ 1.913.0 ] 6 ( 5 ) [ 0.617.0 ] t1 ( sd ) ms931 ( 87 ) 806 ( 52 ) 910 ( 39 ) 1,049 ( 81 ) 944 ( 113 ) t2 * ( sd ) ms15 ( 1 ) 17 ( 3 ) 16 ( 2 ) t2 ( sd ) ms31 ( 2 ) 34 ( 1 ) 32 ( 2 ) adc ( sd ) mm / s0 .3310 ( 0.1 ) 0.4510 ( 0.1 ) 0.3910 ( 0.09 ) the total number ( # ) of nodes found on mri and by pathology , the mean transversal dimensions in millimeters ( mm ) standard deviation ( sd ) and range , the mean t1 , t2 and t2 * relaxation times and the mean apparent diffusion coefficient ( adc ) are depictedfig . 2t1 , t2 and t2 * values ( ms ) as a function of formaldehyde fixation time per axillary lymph node dissection ( alnd ) . the t1 values are depicted by - , the t2 values by andthe t2 * values by lymph node characteristics depicted per axillary lymph node dissection ( alnd ) the total number ( # ) of nodes found on mri and by pathology , the mean transversal dimensions in millimeters ( mm ) standard deviation ( sd ) and range , the mean t1 , t2 and t2 * relaxation times and the mean apparent diffusion coefficient ( adc ) are depicted t1 , t2 and t2 * values ( ms ) as a function of formaldehyde fixation time per axillary lymph node dissection ( alnd ) . the t1 values are depicted by - , the t2 values by and the t2 * values by lymph node t1 values , determined at a room temperature of 20c , were : 931 ms , 806 ms , 910 ms and 1,049 ms for alnd 1 , 2 , 3 and 4 respectively , leading to an overall average t1 of 944 ms . the body - temperature - corrected t1 values for alnd 1 , 2 , 3 and 4 are 1,168 ms , 1,011 ms , 1,140 ms and 1,316 ms respectively , leading to an overall average t1 of 1,316 ms . lymph node adc values , determined at a room temperature of 20c , were : 0.3310 mm / s and 0.4510 mm / s for alnd 3 and 4 respectively , leading to an overall average adc of 0.3910 mm / s . the body - temperature - corrected adc values result in an average adc for alnd 3 and 4 of 0.3510 mm / s and 0.4710 mm / s respectively , leading to an overall average adc of 0.4110 mm / s . twenty - three of 45 nodes ( 51 % ) were observed without a lipid - rich medulla ( fig . the spearman s rank correlation ratio for length , width and length / width ( i.e. the roundness ) of the node correlated to the presence of a lipid centre , was 0.54 for length ( p = 0.0001 [ 95 % ci 0.320.71 ] ) , 0.54 for width ( p = 0.0001 [ 95 % ci 0.310.71 ] ) and 0.031 for roundness3six lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . solid thin arrows : afferent lymph vessels , which conduct lymph towards the convex side of the node . open arrows : efferent lymph vessels , which exit the node on the concave side . fat short arrow : the centre of the hilus , which is of low signal intensity on this mr image . this is most likely due to the presence of fat , which is suppressed and due to the presence of blood vessels . these are also of low signal intensity on mri due to the high susceptibility caused by the iron ( hemoglobin ) content of the erythrocytes in these vessels . these vessels have low signal intensity on the mri scans , due to susceptibility artifacts because of the hemoglobin , iron , content . d f compact spherical nodes with no fatty centres six lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . solid thin arrows : afferent lymph vessels , which conduct lymph towards the convex side of the node . open arrows : efferent lymph vessels , which exit the node on the concave side . fat short arrow : the centre of the hilus , which is of low signal intensity on this mr image . this is most likely due to the presence of fat , which is suppressed and due to the presence of blood vessels . these are also of low signal intensity on mri due to the high susceptibility caused by the iron ( hemoglobin ) content of the erythrocytes in these vessels . these vessels have low signal intensity on the mri scans , due to susceptibility artifacts because of the hemoglobin , iron , content . d f compact spherical nodes with no fatty centres lymph nodes are connected to lymphatic pathways and blood vessels . lymph is conducted to the node through afferent vessels on the convex side . the lymph exits the node through efferent vessels on the concave hilar side , together with the vasculature . typically , there are more afferent than efferent vessels . we visualized many small afferent vessels at nodal convexities and a few , often prominent , efferent vessels exiting the node from the hilus ( fig . 4 ) . the lymph node capsule contains a vascular network which runs parallel to the lymph flow in order to facilitate the exchange of fluid components . these vascular structures can become dilated , which was visualized in figs . 3f , 5a and 6b .4 the hilus of three different nodes on thin - slab maximum intensity projections ( mip ) over 2 mm of a 3d t1w mr image ( 180 m isotropic resolution ) . thin black arrow : b - cell follicle . a an area of low signal intensity is visible in the lymph node capsule . b the mip is oriented in such a way as to depict all efferent vessels and as many afferent vessels as possible .5 three lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . open arrowhead : intranodal dilated blood vessels . a a partial view of a compact spherical node with no fatty centre .6 two lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . a a round shaped lymph node with a fatty centre . a vessel ( encircled ) traverses the capsule of the node . b a horseshoe shaped lymph node with a fatty centre the hilus of three different nodes on thin - slab maximum intensity projections ( mip ) over 2 mm of a 3d t1w mr image ( 180 m isotropic resolution ) . solid white arrows : afferent lymphatic vessels . thin black arrow : b - cell follicle . a an area of low signal intensity is visible in the lymph node capsule . b the mip is oriented in such a way as to depict all efferent vessels and as many afferent vessels as possible . not all afferent vessels can be seen in one view three lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . open arrowhead : intranodal dilated blood vessels . a a partial view of a compact spherical node with no fatty centre . b c bean shaped nodes with fatty centres two lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . open arrowhead : intranodal dilated blood vessels . a a round shaped lymph node with a fatty centre . a vessel ( encircled ) b a horseshoe shaped lymph node with a fatty centre the outer part of the lymph node capsule contains centres called b - cell follicles , which mainly consist of b - cell lymphocytes ; these centres are described as either primary ( inactive ) , or secondary ( activated ) . on 3d t1w mriseveral hypo - intense regions were depicted in the hyper - intense capsule as shown in figs . these structures visualized on mri corresponded to the location of activated b - cell follicles seen at pathology . at pathology these centres had diameters of up to 1.3 mm ( range 0.11.3 mm ) . table 1 shows the number of nodes detected by mri and by pathology and the various mri characteristics per alnd . the influence of conservation time on t1 , t2 and t2 * is shown in fig . 2 . table 1lymph node characteristics depicted per axillary lymph node dissection ( alnd ) alnd 1alnd 2alnd 3alnd4all alnds # of nodes at mri98151951 # of nodes at pathology98121645length ( sd ) [ range ] mm11 ( 6 ) [ 2.719.1 ] 10 ( 7 ) [ 1.321.6 ] 9 ( 8 ) [ 2.127.2 ] 9 ( 7 ) [ 3.024.1 ] 9 ( 7 ) [ 1.327.2 ] width ( sd ) [ range ] mm7 ( 5 ) [ 1.913.2 ] 7 ( 6 ) [ 0.615.8 ] 6 ( 5 ) [ 1.317.0 ] 5 ( 4 ) [ 1.913.0 ] 6 ( 5 ) [ 0.617.0 ] t1 ( sd ) ms931 ( 87 ) 806 ( 52 ) 910 ( 39 ) 1,049 ( 81 ) 944 ( 113 ) t2 * ( sd ) ms15 ( 1 ) 17 ( 3 ) 16 ( 2 ) t2 ( sd ) ms31 ( 2 ) 34 ( 1 ) 32 ( 2 ) adc ( sd ) mm / s0 .3310 ( 0.1 ) 0.4510 ( 0.1 ) 0.3910 ( 0.09 ) the total number ( # ) of nodes found on mri and by pathology , the mean transversal dimensions in millimeters ( mm ) standard deviation ( sd ) and range , the mean t1 , t2 and t2 * relaxation times and the mean apparent diffusion coefficient ( adc ) are depictedfig . 2t1 , t2 and t2 * values ( ms ) as a function of formaldehyde fixation time per axillary lymph node dissection ( alnd ) . the t1 values are depicted by - , the t2 values by and the t2 * values by lymph node characteristics depicted per axillary lymph node dissection ( alnd ) the total number ( # ) of nodes found on mri and by pathology , the mean transversal dimensions in millimeters ( mm ) standard deviation ( sd ) and range , the mean t1 , t2 and t2 * relaxation times and the mean apparent diffusion coefficient ( adc ) are depicted t1 , t2 and t2 * values ( ms ) as a function of formaldehyde fixation time per axillary lymph node dissection ( alnd ) . the t1 values are depicted by - , the t2 values by and the t2 * values by lymph node t1 values , determined at a room temperature of 20c , were : 931 ms , 806 ms , 910 ms and 1,049 ms for alnd 1 , 2 , 3 and 4 respectively , leading to an overall average t1 of 944 ms . the body - temperature - corrected t1 values for alnd 1 , 2 , 3 and 4 are 1,168 ms , 1,011 ms , 1,140 ms and 1,316 ms respectively , leading to an overall average t1 of 1,316 ms . lymph node adc values , determined at a room temperature of 20c , were : 0.3310 mm / s and 0.4510 mm / s for alnd 3 and 4 respectively , leading to an overall average adc of 0.3910 mm / s . the body - temperature - corrected adc values result in an average adc for alnd 3 and 4 of 0.3510 mm / s and 0.4710 mm / s respectively , leading to an overall average adc of 0.4110 mm / s . twenty - three of 45 nodes ( 51 % ) were observed without a lipid - rich medulla ( fig . the spearman s rank correlation ratio for length , width and length / width ( i.e. the roundness ) of the node correlated to the presence of a lipid centre , was 0.54 for length ( p = 0.0001 [ 95 % ci 0.320.71 ] ) , 0.54 for width ( p = 0.0001 [ 95 % ci 0.310.71 ] ) and 0.031 for roundness3six lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . solid thin arrows : afferent lymph vessels , which conduct lymph towards the convex side of the node . open arrows : efferent lymph vessels , which exit the node on the concave side . fat short arrow : the centre of the hilus , which is of low signal intensity on this mr image . this is most likely due to the presence of fat , which is suppressed and due to the presence of blood vessels . these are also of low signal intensity on mri due to the high susceptibility caused by the iron ( hemoglobin ) content of the erythrocytes in these vessels . these vessels have low signal intensity on the mri scans , due to susceptibility artifacts because of the hemoglobin , iron , content . d f compact spherical nodes with no fatty centres six lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . solid thin arrows : afferent lymph vessels , which conduct lymph towards the convex side of the node . open arrows : efferent lymph vessels , which exit the node on the concave side . fat short arrow : the centre of the hilus , which is of low signal intensity on this mr image . this is most likely due to the presence of fat , which is suppressed and due to the presence of blood vessels . these are also of low signal intensity on mri due to the high susceptibility caused by the iron ( hemoglobin ) content of the erythrocytes in these vessels . these vessels have low signal intensity on the mri scans , due to susceptibility artifacts because of the hemoglobin , iron , content . d f compact spherical nodes with no fatty centres lymph nodes are connected to lymphatic pathways and blood vessels . lymph is conducted to the node through afferent vessels on the convex side . the lymph exits the node through efferent vessels on the concave hilar side , together with the vasculature . typically , there are more afferent than efferent vessels . we visualized many small afferent vessels at nodal convexities and a few , often prominent , efferent vessels exiting the node from the hilus ( fig . 4 ) . the lymph node capsule contains a vascular network which runs parallel to the lymph flow in order to facilitate the exchange of fluid components .4 the hilus of three different nodes on thin - slab maximum intensity projections ( mip ) over 2 mm of a 3d t1w mr image ( 180 m isotropic resolution ) . thin black arrow : b - cell follicle . a an area of low signal intensity is visible in the lymph node capsule . b the mip is oriented in such a way as to depict all efferent vessels and as many afferent vessels as possible .5 three lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) .6 two lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . a a round shaped lymph node with a fatty centre . a vessel ( encircled ) traverses the capsule of the node . b a horseshoe shaped lymph node with a fatty centre the hilus of three different nodes on thin - slab maximum intensity projections ( mip ) over 2 mm of a 3d t1w mr image ( 180 m isotropic resolution ) . solid white arrows : afferent lymphatic vessels . b the mip is oriented in such a way as to depict all efferent vessels and as many afferent vessels as possible . not all afferent vessels can be seen in one view three lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . open arrowhead : intranodal dilated blood vessels . a a partial view of a compact spherical node with no fatty centre . b c bean shaped nodes with fatty centres two lymph nodes on 3d t1w images ( 180 m isotropic resolution ) and on matching h & e stained histopathology images ( 1.5 magnification ) . a a round shaped lymph node with a fatty centre . a vessel ( encircled ) traverses the capsule of the node . b a horseshoe shaped lymph node with a fatty centre the outer part of the lymph node capsule contains centres called b - cell follicles , which mainly consist of b - cell lymphocytes ; these centres are described as either primary ( inactive ) , or secondary ( activated ) . on 3d t1w mriseveral hypo - intense regions were depicted in the hyper - intense capsule as shown in figs . these structures visualized on mri corresponded to the location of activated b - cell follicles seen at pathology . at pathology these centres had diameters of up to 1.3 mm ( range 0.11.3 mm ) . we presented the 7 t characterization of ex vivo healthy human axillary lymph nodes with a node - to node correlation to pathology .45 axillary nodes from 4 alnds were characterized on mri and subsequently correlated to pathology . this study is an ex vivo study in which normal lymph node characteristics were assessed at 7 t . taking technological advancements into consideration as well , knowledge gained by analyzing ex vivo nodes can help with a quicker assessment in the future of lymph nodes in vivo in cancer patients . previously luciani et al . performed an ex vivo , node to node correlation study at 1.5 t showing that mri accurately assessed lymph node size , but missed on average 20 % of the nodes found by pathology . by comparison , in this ex vivo study , at 7 t we detected all nodes found at subsequent pathological examination . a likely explanation is the higher imaging - resolution - we used a 55 - times smaller voxel size ( voxel volume 5.8 nanoliter ) - and the higher lymph node to background contrast of the fat - suppressed 3d t1w data set we acquired . moreover , mri detected nine more nodes than were retrieved at subsequent standard pathological examination of the alnds . therefore in theory these would have to be considered false positives when using pathology as the gold standard . however their morphological appearance and their t2 ( 332 ms ) and t2 * ( 172 ms ) characteristics closely matched those of histologically - confirmed lymph nodes . also anatomically , no other structures of corresponding size and shape are present in alnd specimens . for these particular nodes the mean t1 valuecould not be determined because they were not visualized on the ( single slice ) look - locker data set , and the adc was of insufficient resolution for accurate roi analysis . these nodes were only retrieved by the pathologist on the basis of the mri , one after direct consultation of the mri - based map for its precise location and two others after the specimen was more thoroughly defatted because the mri - based map indicated more nodes should be present . the data therefore suggest that mri has the potential to detect even more nodes than standard clinical pathological examination . additionally , it is shown that size and shape of histologically - proven benign human lymph nodes can vary greatly . larger lymph nodes were more likely to have a fatty centre than smaller lymph nodes . this is useful for their putative discrimination from malignant lymph nodes which are also , on average , larger , but often do not contain a fatty centre . in the present study all nodes were histologically proven benign nodes , but this issue is addressed in an ongoing 7 t study in lymph nodes derived from breast cancer patients . with respect to metastatic morphology ; the roundness of nodes did not correlate with the presence of a fatty centre . in addition , while a diameter greater than 10 by 15 mm on transverse images is often used as a cut - off for the detection of metastatic nodes , the diameter of the healthy nodes in this study - also measured in the transversal imaging plane - varied from 0.6 to 17.0 mm by 1.3 to 27.2 mm . however , also pathologically , lymph vessels can only be differentiated from blood vessels with certainty if valves ( lymph vessels ) or erythrocytes ( blood vessels ) are present . several putative secondary b - cell follicles situated in the periphery of the nodes were observed . at pathologythese nodes were normal reactive lymph nodes with multiple , activated b - cell follicles . the signal intensity of these follicles was not as hypo - intense as the hypo - intensity caused by the presence of erythrocytes ( fig .6 ) which are found in blood vessels , nor was the shape of the structure similar to vessels . it is important to note that these areas of hypo - intensity in the nodal capsule on the ( non - contrast - enhanced ) t1w images are not metastatic involvement . mean absolute t1 , t2 and adc values of ex vivo healthy human axillary nodes at 7 t were 944 ms , 32 ms and 0.3910 mm / s respectively . the high sensitivity of t2 * to field heterogeneity often precludes the direct comparison of these values between different studies . but given the similar t2 * values measured in this study , this effect seems to be reproducible in practice for the current set - up . the quantitative measurements in the post - mortem specimens are influenced amongst others by fixation effects of formaldehyde and by temperature . therefore these data can not be extrapolated directly to in vivo conditions . with respect to the temperature , the determined ex vivo values can be corrected as shown in the materials and methods section ; but correction for the effect of fixation on cellular metabolism is not possible . especially for t1 valuesthis effect was also visible in our study as shown in fig . 2 . therefore , the reported absolute values can not be directly compared to absolute values determined in vivo . for ex vivo studies , these measurements could nonetheless serve as a reference value for the future comparison of ex vivo healthy lymph nodes to metastatic nodes . mri detected at least as many nodes in the alnd specimens as detected by standard clinical pathological examination and it visualized great structural detail such as efferent - and afferent vessels , intranodal capillary structures and several putative b - cell follicles . the detailed anatomical imaging , in addition to the quantitative analyses , of healthy nodes may support a better assessment of metastatic nodes in the future . previously luciani et al . performed an ex vivo , node to node correlation study at 1.5 t showing that mri accurately assessed lymph node size , but missed on average 20 % of the nodes found by pathology . by comparison , in this ex vivo study , at 7 t we detected all nodes found at subsequent pathological examination . a likely explanation is the higher imaging - resolution - we used a 55 - times smaller voxel size ( voxel volume 5.8 nanoliter ) - and the higher lymph node to background contrast of the fat - suppressed 3d t1w data set we acquired . moreover , mri detected nine more nodes than were retrieved at subsequent standard pathological examination of the alnds . therefore in theory these would have to be considered false positives when using pathology as the gold standard . however their morphological appearance and their t2 ( 332 ms ) and t2 * ( 172 ms ) characteristics closely matched those of histologically - confirmed lymph nodes . also anatomically , no other structures of corresponding size and shape are present in alnd specimens . for these particular nodes the mean t1 value could not be determined because they were not visualized on the ( single slice ) look - locker data set , and the adc was of insufficient resolution for accurate roi analysis . these nodes were only retrieved by the pathologist on the basis of the mri , one after direct consultation of the mri - based map for its precise location and two others after the specimen was more thoroughly defatted because the mri - based map indicated more nodes should be present . the data therefore suggest that mri has the potential to detect even more nodes than standard clinical pathological examination . additionally , it is shown that size and shape of histologically - proven benign human lymph nodes can vary greatly . larger lymph nodes were more likely to have a fatty centre than smaller lymph nodes . this is useful for their putative discrimination from malignant lymph nodes which are also , on average , larger , but often do not contain a fatty centre . in the present study all nodes were histologically proven benign nodes , but this issue is addressed in an ongoing 7 t study in lymph nodes derived from breast cancer patients . with respect to metastatic morphology ; the roundness of nodes did not correlate with the presence of a fatty centre . in addition , while a diameter greater than 10 by 15 mm on transverse images is often used as a cut - off for the detection of metastatic nodes , the diameter of the healthy nodes in this study - also measured in the transversal imaging plane - varied from 0.6 to 17.0 mm by 1.3 to 27.2 mm . however , also pathologically , lymph vessels can only be differentiated from blood vessels with certainty if valves ( lymph vessels ) or erythrocytes ( blood vessels ) are present . several putative secondary b - cell follicles situated in the periphery of the nodes were observed . at pathologythese nodes were normal reactive lymph nodes with multiple , activated b - cell follicles . the signal intensity of these follicles was not as hypo - intense as the hypo - intensity caused by the presence of erythrocytes ( fig .6 ) which are found in blood vessels , nor was the shape of the structure similar to vessels . it is important to note that these areas of hypo - intensity in the nodal capsule on the ( non - contrast - enhanced ) t1w images are not metastatic involvement . mean absolute t1 , t2 and adc values of ex vivo healthy human axillary nodes at 7 t were 944 ms , 32 ms and 0.3910 mm / s respectively . absolute t2 * values were also determined . the high sensitivity of t2 * to field heterogeneity often precludes the direct comparison of these values between different studies . but given the similar t2 * values measured in this study , this effect seems to be reproducible in practice for the current set - up . the quantitative measurements in the post - mortem specimens are influenced amongst others by fixation effects of formaldehyde and by temperature . therefore these data can not be extrapolated directly to in vivo conditions . with respect to the temperature , the determined ex vivo values can be corrected as shown in the materials and methods section ; but correction for the effect of fixation on cellular metabolism is not possible . especially for t1 valuesthis effect was also visible in our study as shown in fig . 2 . therefore , the reported absolute values can not be directly compared to absolute values determined in vivo . for ex vivo studies , these measurements could nonetheless serve as a reference value for the future comparison of ex vivo healthy lymph nodes to metastatic nodes . mri detected at least as many nodes in the alnd specimens as detected by standard clinical pathological examination and it visualized great structural detail such as efferent - and afferent vessels , intranodal capillary structures and several putative b - cell follicles . the detailed anatomical imaging , in addition to the quantitative analyses , of healthy nodes may support a better assessment of metastatic nodes in the future .\noutput:\n" }, { "from": "agent", "value": "objectiveto characterize ex vivo healthy human axillary lymph nodes on 7 tesla mri and to correlate the findings with pathological analysis as a first step towards non - invasive staging of breast cancer patients in the future.methodsfour axillary lymph node dissection ( alnd ) specimens from 2 autopsy patients , who had no cancer , were examined on a clinical 7 tesla mri system . for morphological analysis a 3d t1 - weighted fat - suppressed fast - field - echo [ isotropic resolution 180 m ] was acquired . for quantitative analyses 2d t1 - , 3d t2 - , t2 * - and diffusion - weighted images were acquired . the alnds were mapped and stained for precise correlation of mri to pathology . nodes were sliced in 3 m sections , haematoxylin & eosin stained , and examined by an experienced pathologist.resultsmri detected all 45 nodes and 6 additional nodes that were not detected at pathological analysis . b - cell follicles , efferent - and afferent lymph vessels and blood vessels were identified . mean t1 , t2 , t2 * , adc values ( standard deviation ) were 944 113 ms , 32 2 ms , 16 2 ms , 0.39 0.09103 mm2 / s , respectively.conclusions7 tesla mri of ex vivo human axillary lymph nodes correlated well with pathology . mri detected all nodes present in the specimens and allowed visualization of fine structural detail . pathology - correlated quantitative mri data are presented ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: various techniques have been formulated to obtain favourable conditions for intubation and one such technique is the priming technique . priming principle refers to administration of a small dose of non - depolarising blocker which when followed by a large intubating dose after 2 - 4 min produces a relatively rapid and profound blockade to ensure a suitable condition for endotracheal intubation . the theory behind this principle is that a small dose of non - depolarizing agent can block large number of acetylcholine receptors at the neuromuscular junctions ( nmj ) before appreciable clinical reduction in neuromuscular transmission . the second larger dose blocks the remaining receptors and effects more rapid onset of intubating conditions . when using the priming principle to accelerate the onset of neuromuscular blockade , the initial dose should not exceed 10 % of the drug 's ed95 . the priming technique is considered clinically superior to the bolus method and is preferred in all elective cases and in those patients in whom succinylcholine is contraindicated . the effects of pretreatment of three different non - depolarising muscle relaxants , rocuronium , vecuronium and atracurium on the facilitation of endotracheal intubation with rocuronium are compared as also the haemodynamic changes and adverse effects , if any . a double - blinded , randomised controlled prospective study was conducted at a tertiary health care hospital between september 2010 and august 2012 . after obtaining approval by the institutional ethics committee , 105 patients of american society of anaesthesiologists physical status i and ii aged between 20 and 60 years , both sexes , undergoing surgeries under general anaesthesia , patients with renal diseases , hepatic diseases , neurological disorders and neuropathies , cardiovascular diseases and respiratory problems with anticipated airway difficulties , any known allergy to study drugs were excluded from the study . based on previous studies , it was calculated that a sample size of 28 patients would be required per group to demonstrate a clinically significant difference among the groups for improving intubating conditions , at = 0.05 with a power ( 1 - ) of 80 % . in order to improve the weight of the results , of the study , 35 patients were enrolled for each group . patients were randomly allocated into three groups by computer generated randomisation chart to receive the drugs during the study as follows : group a ( n = 35 ) - rocuronium ( 0.06 mg / kg body weight ) , group b ( n = 35 ) - vecuronium ( 0.01 mg / kg body weight ) and group c ( n = 35 ) - atracurium ( 0.05 mg / kg body weight ) . on arrival at the operation theatre , the patients were connected to the monitors for measuring the heart rate ( hr ) , blood pressure ( bp ) , electrocardiogram , peripheral oxygen saturation ( spo2 ) , and the baseline values of these variables were recorded . for neuromuscular monitoring , a peripheral nerve stimulatorthen , a priming dose of the test drug ( 10 % of the ed95 ) , which was prepared and loaded in a syringe by an assistant not involved in the assessment , was administered . this was followed by preoxygenation with 100 % oxygen over 2 min and the anaesthesia was induced with injection thiopentone sodium until the loss of eye lash reflex .90 % ( 0.54 mg / kg body weight ) of the calculated intubating dose ( 0.6 mg / kg body weight ) of rocuronium was administered to facilitate endotracheal intubation . the ulnar nerve was stimulated percutaneously at the wrist joint immediately after administering the intubating bolus dose . the electromagnetic response of single twitch contractions ( 0.1 hz ) of adductor pollicis muscle obtained by stimulation of ulnar nerve with supra maximal stimulus of 0.2 ms duration was recorded . oxygenation was continued and endotracheal intubation was attempted at 60s from the end of rocuronium injection . the single twitch height was first recorded immediately after the administration of the intubating dose of rocuronium and at the end of 60s ; another single twitch response was recorded . consisting of a total score of 9 in relation to jaw relaxation , condition of the vocal cords and response to intubation , which are graded as excellent ( if score is 8 - 9 ) , good ( if score is 6 - 7 ) , fair ( if score is 3 - 5 ) and poor ( if score is 0 - 2 ] ) . after successful intubationvital haemodynamic parameters were recorded at 0 , 1 , 2 , 3 , 4 , 5 and 10 min following intubation .0 minute was defined as the point of time where the remaining 90 % of the intubating dose of rocuronium was administered following the priming dose . patients were extubated after the return of airway protective reflexes and monitored in post anaesthetic care unit ( pacu ) before transfer to the pacu . the parameters and patient data were recorded and entered in microsoft excel sheet ( microsoft office 2007 professional ) and compared among the three groups using anova test for categorical variable , student 's t - test for continuous variables , and p 0.05 was deemed significant . statistical package for social sciences ( spss ) for windows version 16.0 software , chicago , spss inc . was used for statistical analysis . the age , weight , and sex distribution of the three groups were uniform and comparable [ table 1 ] . the hr [ figure 1 ] rose from the baseline value reaching its maximum value at 1 min and thereafter receded even though it did not come down near the baseline value in all three groups . the three groups when compared showed no significant difference in hr at different time intervals ( p 0.05 ) . the distribution of patient 's demographic profile in three groups the distribution of pulse rate ( rate per minute ) in the three groups at different time intervals the systolic blood pressure ( sbp ) in all the three groups rose from the baseline value reaching its maximum in the 0 min even though the rise was highly significant throughout all the time intervals [ figure 2 ] . the changes in sbp when the three groups were compared by f test at different time intervals showed no significant difference ( p 0.05 ) . the variation in sbp from the baseline value till the first 5 min was significant within all three groups . the distribution of systolic blood pressure ( in mmhg ) in the three groups at different time intervals the changes in the mean arterial bp [ figure 3 ] followed the same trend as that of sbp . the three groups when compared together at different time intervals showed no significant differences ( not statistically significant ) among the groups . the distribution of mean arterial pressure ( in mmhg ) in the three groups at different time intervals single twitch height measured just before the intubation ( t2 ) showed significant change when compared with baseline ( t1 ) , noted immediately after administration of intubating dose of rocuronium in all the three groups as shown in table 2 . when the twitch heights were compared in between the groups , significant difference was noted only between the twitch heights at intubation , of groups b and c. the distribution of single twitch height in the three groups grading of the quality of intubating conditions is shown in table 3 . maximum number of excellent intubating conditions was observed in group c. intubating conditions were excellent in 85.71 % , 88.57 % , and 97.14 % in groups a , b , and c respectively . fair intubating conditions were seen in only 1 patient from group a. the distribution of intubating condition level - wise in the three groupssince the first report of the priming principle as a method to accelerate the onset of neuromuscular block as well as to provide excellent intubation conditions , many investigations directed to optimise the priming technique have been performed . several workers used small doses of vecuronium ( 0.015 mg / kg ) and proved that administration of vecuronium in divided doses gave satisfactory intubating conditions in majority of patients . recentlyrao et al . proved that priming with rocuronium provides excellent intubating conditions in 60s with no adverse effects . the synergistic effect of rocuronium when combined with itself or with various other non - depolarizing muscle relaxants have been observed in priming studies . in a retrospective study by patanwala et al . , first attempt successful intubation with rocuronium ( 72.6 % ) and succinylcholine ( 72.9 % ) were similar . in this study , surprisingly , 100 % first attempt successful intubations were seen 60s after administering the bolus dose . the least possible dose of rocuronium ( 0.6 mg / kg ) was used as bolus for intubation as against higher doses used by some studies and excellent intubating conditions were achieved . were of the opinion that , when using the priming principle to accelerate the onset of neuromuscular blockade , the initial dose should nt exceed 10 % of the drug 's ed95 . respectively used 0.015 mg / kg vecuronium , 0.015 mg / kg vecuronium , ( 0.01 mg / kg ) vecuronium and 0.05 mg / kg atracurium as priming doses . accordingly , the priming dose used in this study was guided by the above mentioned studies . though the onset time was not studied , the priming interval of 3 min was adopted as done by yavascaoglu et al . and endotracheal intubation performed 60s after the bolus dose . this is a shorter priming interval when compared with that of tripathi and pandey et al . who advocated a priming interval of not 5 min . several workers explained the entropy suppression and haemodynamic stability respectively provided by rocuronium at optimum doses and was hailed as the drug of choice with optimum dose and a preferable drug for intubation for avoiding the side effects of succinylcholine . observed limited increase in hr without change in map and attributed this effect to the weak vagolytic activity of rocuronium . in the present study , there was statistically insignificant change in map in the three groups at all - time intervals . however , statistically significant but clinically insignificant increase in map at 0 and 1 min was observed . this increase in map at 0 min could be due to the haemodynamic responses induced by rocuronium injection pain , and the increase at 1 min could be due to the sympathetic stimulation produced due to laryngoscopy and intubation . simultaneously , there were no statistically significant differences in the hr , even though it increased from the baseline value in all the groups till the 3 min . this rise in hr following intubation as found in all the groups may be the result of the usual responses to laryngoscopy and intubation . even though the study of haemodynamic changes was not the primary aim , it was studied as a secondary outcome of the study , and we observed an increase in haemodynamic parameters at various time intervals in all the three study groups after the bolus dose of rocuronium . no significant differences were observed between the quantitative values of each component of intubating score in the present study . all the patients could be intubated at 1 min after the bolus dose of rocuronium was given . this is in agreement with the study by cooper et al . who explained the rapid onset of neuromuscular block to be due to the low potency of rocuronium , which results in a high molecular load being present at the nmj , producing an initial high concentration gradient and transfer of molecules of the drug to the biophase . similar findings were observed by different workers and this could be because of the fact that when rocuronium is combined in equipotent doses with other non - depolarizing agent , it acts synergistically in the early part of blockade . though statistically insignificant , establishment of excellent intubating conditions in 97.14 % of patients in atracurium primed group as against 88.57 % vecuronium and 85.71 % rocuronium primed group may suggest a greater synergism between two drugs belonging to structurally different groups - atracurium being a non - steroidal benzylisoquinolone compound and rocuronium a mono quaternary steroid . though single twitch response was recorded just before intubation , it was not used as the guiding parameter . the baseline twitch height was 98.74 % ( recorded after administering bolus dose ) and 34.80 % just before intubation . intergroup comparison showed significant difference only between the single twitch response recorded in vecuronium and atracurium groups just before intubation . however , when the intubating grades were compared , more number of patients in the atracurium primed group had excellent intubating conditions . withdrawal response was seen in 3 , 2 and 1 patient in rocuronium , vecuronium and atracurium groups respectively . a study by borgeat and kwiatkowski has shown that injection of rocuronium is associated with severe , burning pain of short duration responsible for spontaneous movements in the arm observed after induction of anaesthesia . however , intubating conditions were excellent in all these patients . priming technique alleviated the withdrawal responses associated with intravenous administration of rocuronium as only 6 patients ( 0.05 % ) showed withdrawal response to rocuronium injection . this is in agreement with the study by lee et al . who found similar results . no symptoms of muscle weakness were observed which may be compared with the findings of abdulatif et al . there were a few limitations in this study which included the following : the priming effect of the various agents could have been assessed at a shorter point of time than the predetermined time of 60s . the pharmacokinetics of the agents along with the economical aspect of the study could have been assessed . the confounding effects of rocuronium injection and laryngoscopy and intubation on haemodynamic responses could have been further addressed . there is a strong possibility that endotracheal intubation could have been successfully performed earlier than 60s as it is possible to do so when the intubating conditions were onlygood , a presumptive event which might have happened before the establishment of excellent conditions in almost 90 % of cases at 60s . however , we were guided by the recommendation that intubation should be performed at 60s with rocuronium ( 0.6 mg / kg ) . though the study did not prove a significant difference in intubating conditions among the three groups , it explains the efficacy of using priming principle for attaining excellent intubating conditions proved by numerous studies .\noutput:\n" }, { "from": "agent", "value": "background and aims : priming principle refers to administration of a small dose of non - depolarising blocker , which when followed by a large intubating dose produces a relatively rapid and profound blockade to ensure suitable conditions for endotracheal intubation . we aimed to compare the effects of rocuronium , vecuronium , and atracurium as pretreatment drugs on intubating conditions with rocuronium facilitated endotracheal intubation.methods : this double - blinded , randomised controlled prospective study was carried out at a tertiary health care hospital on patients undergoing surgical procedures under general anaesthesia . they were randomly allocated into three groups ( n = 35 ) by computer generated randomisation chart to receive either rocuronium ( 0.06 mg / kg body weight ) ( group a ) ; vecuronium ( 0.01 mg / kg body weight ) ( group b ) or , atracurium ( 0.05 mg / kg body weight ) ( group c ) , followed by intubating dose ( 0.6 mg / kg body weight ) of rocuronium . the haemodynamic parameters and intubating conditions were studied and statistically analysed by anova test and student 's t - test as applicable using statistical package for the social sciences 16.0 for windows ( spss inc . , chicago , il , usa ) . results : excellent intubating conditions were noted in maximum number of patients in group c ( 97.41 % ) . no significant differences were observed in the systolic blood pressure in all the three groups at all - time intervals . the mean arterial pressure rose significantly from baseline value to maximum , at 0 min in all the groups ; however , no significant difference was observed amongst the groups ( p > 0.05 ) . conclusion : pretreatment with rocuronium bromide can facilitate endotracheal intubation in 60 s irrespective of non - depolarising muscle relaxants used for priming ; however , it can not attenuate haemodynamic changes associated with laryngoscopy and intubation ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: thyroid dysfunction is one of the most common endocrine disorders in women of childbearing age , second only to diabetes mellitus . approximately 2 - 3 % of women are diagnosed prenatally with abnormal thyroid function ; however , a greater number may go undetected due to lack of consensus on testing and treatment modalities during pregnancy . normal maternal thyroid function is critical for early fetal development , as the fetus does not produce thyroid hormones until the end of the first trimester ( ~ 1214 weeks gestation ) and , prior to that time , is solely dependent on the mother 's hormone supply . the impact of thyroid dysfunction , particularly hypothyroidism , during pregnancy is well documented , and the associated adverse fetal / infant outcomes range from preterm delivery to fetal death . abnormal maternal thyroid hormone levels during gestation are also linked to long - term effects in older offspring including delayed learning , lowered iq , and hearing deficits . a number of women may be biochemically euthyroid or exhibit thyroid hormone levels within normal limits but test positive for thyroid autoantibodies such as thyroperoxidase ( tpo ) antibody . in fact , it is estimated that 10 % of pregnant women are tpo positive ; however , fewer studies have assessed the influence of tpo status on fetal / infant outcomes among euthyroid mothers . limited research tends to suggest that tpo positivity , independent of abnormal thyroid levels , may increase the risk of placental abruption , spontaneous miscarriage , and perinatal death . even fewer studies have assessed the impact of maternal tpo antibody status on infant specific variables such anthropometric measurements at delivery although these studies have produced conflicting results . to further explore the relationship between maternal autoantibody status and infant outcomes , this study uniquely examined the influence of maternal tpo status on fetal / infant brain growth at delivery , which has been linked to cognitive function in childhood . this project was undertaken with the following hypotheses : ( 1 ) at delivery , newborns of tpo + mothers will exhibit impaired body growth as indicated by reduced birth weight and birth length ; ( 2 ) at delivery , infants born to tpo + mothers will exhibit impaired brain growth as exhibited by reduced head circumference and calculated brain weight . pregnant women ( n = 631 ) were recruited from prenatal clinics in tampa , florida , and the surrounding area between november 2007 and december 2010 . women were eligible for participation in the study if they were between 18 and 45 years of age , 16 to 25 weeks gestation , able to understand and speak the recruiter 's language ( english or spanish ) , and essentially healthy without plans to terminate the pregnancy or relocate prior to 6 months postpartum . exclusion criteria included known autoimmune disease , previous thyroid disease , presence of chronic diseases / conditions including hiv , use of medications that affect immunity , mental illness , body mass index ( bmi ) 20 , current multiple gestation , current pregnancy product of invitro fertilization ( ivf ) , and fetal abnormalities . thyroperoxidase antibody status was measured for all participants at the time of enrollment and women were classified as tpo positive or negative . thyroid stimulating hormone ( tsh ) levels were measured for all tpo positive women at the time of enrollment . tpo status was determined in 631 plasma samples according to kit directions by elisa ( orgentec , mainz , germany ) using standards and controls . tpo antibody titer greater than 20 ius / ml was used as the cutoff value for determining positivity , since a value from 0 to 20 is considered within normal range . the mean tpo titers for each group were 75.659.2 and 9.44.5 , respectively . newborn anthropometric measurements were retrieved from maternal delivery records including ultrasound - derived gestational age in weeks , birth weight ( grams ) , birth length ( centimeters ( cm ) ) , head circumference ( cm ) , abdominal circumference ( cm ) , and chest circumference ( cm ) . infant head circumference at birth was used to derive two additional indices of fetal brain size : brain weight , and brain - to - body ratio ( bbr ) . brain weight was estimated from the following formula : brain weight ( g ) = 0.037 head circumference ( cm ) , which is derived from the national institute of neurological and communicative disorders and stroke 's collaborative perinatal project . brain - to - body ratio ( bbr ) was defined as 100 the ratio of the infant 's estimated brain weight to its birth weight . this is the percentage of the infant 's birth weight that is estimated to reside in the brain . since the brain weight is a function of the head circumference , the formula could thus be rewritten in terms of birth weight and head circumference as bbr = 100 [ 0.037 head circumference ( cm ) ] / birth weight ( g ) . a high bbr is indicative of a higher proportion of birth weight residing in the brain , while a lower bbr indicates a lower percentage of birth weight residing in the brain . for the current study , multiple gestation pregnancies ( n = 6 ) and pregnancies resulting in fetal demise ( n = 4 ) were excluded . to promote homogeneity of the sample and reduce confounding factors , analysis was restricted to term infants only ( 37 weeks gestation ) , resulting in a final study sample of 528 women who delivered term infants . chi - square test and two - sample t - test were used to assess differences in sociodemographic characteristics between tpo + and tpo mothers . mean differences in growth parameters were examined by maternal tpo status using t - test . multiple regression analysis was used to demonstrate the influence of tpo status on continuous outcomes such as birth weight , birth length , and head circumference . the covariates in the regression models were selected a priori based on information in the published literature . these variables included maternal age , parity , race / ethnicity ( white non - hispanic ; black non - hispanic , hispanic and other ) , marital status , prenatal smoking habits , prepregnancy body mass index ( bmi ) , delivery type and gender of the infant . several variables were dichotomized in the regression models : parity ( nulliparous * or multiparous ) , marital status ( married * or unmarried ) , smoking habits ( smoker or nonsmoker * ) , pre - pregnancy bmi ( overweight ( bmi 25 ) or nonoverweight * ) , delivery type ( vaginal * or cesarean ) , and infant gender ( male * or female ) . additionally , adjusted estimates were derived in all cases by using tpo negative participants as the referent category . a combination of graphic methods and statistical tests were used to check for violations of the regression assumptions . after fitting the linear regression models to the data , the normality assumption was assessed by visual inspection of the residual normal qq plots and by use of the shapiro - wilk test . visual inspection of residual scatter plots of outcome variables and errors of prediction were evaluated to ensure that the homoscedasticity assumption was not violated . sas version 9.3 ( sas institute , cary , nc ) was used to perform all analyses . the final study sample ( n = 528 ) comprised pregnant women with a mean age of 28.035.85 years ( range 1845 ) . nearly 48 % ( n = 253 ) of the sample were white , 59 % ( n = 309 ) were married , and less than 6 % ( n = 30 ) were smokers . the mean gestational age at delivery of the term infants retained in the sample was 39.021.10 ( range 3741 weeks ) . approximately 11 % ( n = 58 ) of the final sample tested positive for the thyroperoxidase antibody during pregnancy with a mean tsh level of 1.461.12 . women who tested positive for the tpo antibody did not differ significantly from their negative counterparts in terms of racial / ethnic background , marital status , smoking habits , or body mass index . tpo + mothers tended to be older in age and were more likely to deliver female infants ; however , neither of these factors achieved statistical significance . analyses of mean gestational age at delivery showed that white non - hispanic and hispanic mothers were more likely to deliver infants at 39 + weeks gestation compared to black mothers and mothers in the other racial / ethnic category ( data not shown ) . no differences were noted in delivery type ( vaginal versus cesarean ) or 1 - minute apgar score . also , no differences in mean newborn birth weight , birth length , abdominal circumference , or chest circumference were observed between the two groups ( table 2 ) . nonetheless , small but significant differences were noted for the mean head circumference measurements among infants born to tpo + mothers versus tpo mothers ( 34.45 cm 1.34 sd versus 34.86 cm 1.45 , resp . additionally , infants born to tpo + mothers had significantly smaller brain weight than those born to tpo mothers . unadjusted regression analysis for brain growth variables at delivery indicated that infants born to mothers who were tpo + had a smaller head circumference and reduced brain weight ( = 407 ; standard error ( se ) = 0.200 ; p 0.05 and = 10.307 ; se = 5.001 ; p 0.05 , resp . ) . infants born to mothers with tpo positivity also showed a tendency for lower brain - to - body ratio ; however , the results were not significant ( figure 2 ) . unadjusted analysis did not signify an association between tpo status and newborn growth variables ( birth weight , birth length , abdominal circumference , or chest circumference ) . table 3 summarizes the adjusted multiple regression results for fetal / infant brain growth variables . after adjusting for several maternal and pregnancy factors including maternal age , smoking habits , and infant weight at birth , the relationship between tpo status and infant head circumference at birth was not significant in the overall population but was highly significant among infants born to white non - hispanic mothers ( = 0.727 ; standard error ( se ) = 0.214 ; p 0.001 ) and among those in the other racial / ethnic group ( = 1.636 ; se = 0.713 ; p 0.05 ) , distinguishing race / ethnicity as an effect modifier in the relationship between maternal tpo status and fetal brain growth . the association between tpo positivity and reduced fetal / infant brain weight persisted among infants whose mothers were categorized in either the white non - hispanic or other racial / ethnic groups . table 3 also reflects that the association between maternal tpo status and brain - to - body ratio was significant among infants born to tpo + non - hispanic white mothers only . in this study population , birth weight , birth length , abdominal circumference , and chest circumference were not associated with tpo status ( table 4 ) . this study examined the relationship between maternal thyroid peroxidase antibody status and newborn brain and body growth measurements within a cohort of euthyroid pregnant women . the findings indicate that maternal race / ethnicity modifies the relationship between tpo positivity and reduced brain growth measurements at delivery ( head circumference , brain weight and brain - to - body ratio ) . upon closer examination , the relationship appears to be the most noticeable among white non - hispanic mothers . although this analysis indicates that tpo positivity may result in impaired brain growth among infants of mothers in the other racial / ethnic category , this finding should be interpreted with caution due to the small sample size of this subgroup ( n = 37 ) . however , it can be theorized that the differences in brain growth measurements are more marked among white non - hispanic infants because they are more likely than their nonwhite counterparts to deliver later term ( 39 + weeks gestation ) , thus allowing the differences in brain growth variables to be more apparent . however , nonwhite mothers have a tendency to deliver earlier term infants who may not have had the opportunity to reach full potential , thereby masking the effects of tpo influence . the present analysis did not indicate a significant relationship between tpo status and infant birth weight in this study sample . this finding is contradictory to those studies that have reported increased likelihood of low birth weight infants born to tpo + mothers and an increased likelihood of large - for - gestational age infants born to tpo + women . similar to previously published studies , this analysis did not find a difference in the birth length , abdominal circumference , or chest circumference of infants born to tpo + mothers compared to those born to tpo mothers . although measurement of thyroid antibodies does not give any indication of thyroid function , the presence of tpo antibodies may be associated with decreased thyroid functional reserve during pregnancy . reduced functional thyroid reserve in combination with the normal physiological changes in pregnancy could contribute to minor alterations in circulating thyroid hormone concentrations while remaining within the normal reference range . some researchers hypothesize that the presence of tpo antibodies during a time of increasing thyroid hormone demand such as pregnancy implies that the mother may become hypothyroid during gestation and that transient maternal hypothyroidism may ultimately be responsible for the adverse outcomes . however , previous studies have reported the detrimental effects of tpo antibodies independent of abnormal thyroid hormone levels or disorders . results of this study support this assumption , as our findings indicate that tpo antibodies are associated with reduced brain growth measurements among infants born to a vulnerable subgroup of euthyroid women . a notable strength of this study is the prospective design , as many of the previous studies were retrospective in nature . additionally , laboratory analysis of thyroid stimulating hormone ( tsh ) was used to confirm euthyroid state among participating mothers . the outcome variables were extracted from maternal delivery records ; therefore , measurements were not influenced by knowledge of maternal tpo status . one limitation of this study is the lack of laboratory confirmed prenatal tsh data on women in the tpo negative group . this group was presumed to be euthyroid based on the absence of thyroid dysfunction symptoms and the stringency of the study exclusion criteria ( e.g. , no history of thyroid disease or autoimmune conditions ) . however , it is unlikely that this limitation influenced the study findings , as thyroid dysfunction in the tpo group would have biased the results toward the null and resulted in nonsignificant findings in the association between tpo positivity and fetal / infant brain growth . additionally , postpartum tsh levels were measured on a subsample of the participants resulting in mean values of 3.174.73 for tpo + women ( n = 47 ) and 2.051.80 for tpo women ( n = 41 ) , thus providing additional evidence that the study sample was indeed euthyroid perinatally and hormone levels were within normal limits . after controlling for several maternal and pregnancy factors , tpo positivity was associated with smaller head circumference , reduced brain weight and lower brain - to - body ratio . however , the influence of tpo status on brain growth was modified by maternal race . future studies should focus on the identification of genetic variants or single nucleotide polymorphisms ( snps ) , which could elucidate the interaction between maternal tpo status and race / ethnicity . this is potentially important because findings from recent studies indicate that substitutive treatment with levothyroxine may lower the chance of adverse obstetric outcomes ( miscarriage and premature delivery ) among euthyroid pregnant women who are positive for tpo autoantibodies . considering the long - term implications of impaired fetal / newborn growthmaternal thyroid antibody status during pregnancy may be one of those factors that play a role in fetal growth impairment but is currently being overlooked due to lack of consensus on maternal testing and treatment . at present , tpo antibody status is not assessed as part of the standard prenatal care laboratory work - up , but this study suggests that fetal brain growth may be impaired with tpo positivity among certain populations ; therefore , autoantibody screening among high - risk subgroups may be useful for clinicians to determine whether prenatal thyroid treatment is warranted .\noutput:\n" }, { "from": "agent", "value": "the obstetric consequences of abnormal thyroid function during pregnancy have been established . less understood is the influence of maternal thyroid autoantibodies on infant outcomes . the objective of this study was to examine the influence of maternal thyroperoxidase ( tpo ) status on fetal / infant brain and body growth . six - hundred thirty - one ( 631 ) euthyroid pregnant women were recruited from prenatal clinics in tampa bay , florida , and the surrounding area between november 2007 and december 2010 . tpo status was determined during pregnancy and fetal / infant brain and body growth variables were assessed at delivery . regression analysis revealed maternal that tpo positivity was significantly associated with smaller head circumference , reduced brain weight , and lower brain - to - body ratio among infants born to tpo + white , non - hispanic mothers only , distinguishing race / ethnicity as an effect modifier in the relationship . no significant differences were noted in body growth measurements among infants born to tpo positive mothers of any racial / ethnic group . currently , tpo antibody status is not assessed as part of the standard prenatal care laboratory work - up , but findings from this study suggest that fetal brain growth may be impaired by tpo positivity among certain populations ; therefore autoantibody screening among high - risk subgroups may be useful for clinicians to determine whether prenatal thyroid treatment is warranted ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: hepatitis c virus ( hcv ) infection has been associated with various extrahepatic manifestations , and diabetes mellitus is one of these . diabetes in patients with chronic hepatitis c infection ( chc ) has unique and complex pathogenesis , which distinguishes this metabolic disorder from type 2 diabetes mellitus . in this regard , a high prevalence of diabetes has been reported in hcv - infected patients in comparison with other liver diseases . mehta et al . have reported that preexisting hcv infection may increase the risk of type 2 diabetes mellitus in patients with recognized diabetes risk factors . the mechanisms by which chronic hepatitis c infection induces increased insulin resistance and the risk for development of diabetes have not been completely clarified . it has been observed that type 2 diabetes mellitus occurs in the early stages of liver disease . in the light of these observations , the mechanism through which chronic hepatitis c infection is associated with insulin resistance may involve direct viral effects , proinflammatory cytokines , and suppressors of cytokine signaling ( reviewed in ) . in particular , inflammation has been hypothesized to underlie not only the pathogenesis of the diabetes but also its association with cardiovascular diseases . numerous studies , especially in normal individuals , have shown that crp levels in the highest quantile predict cardiovascular events . similarly , both white blood cell ( wbc ) count and erythrocyte sedimentation rate ( esr ) have been associated with cardiovascular risk . there is also evidence supporting the suggestion that crp levels are increased in diabetes . moreover , accumulated evidence suggests that hcv increases the risk of atherosclerotic cardiovascular disease by causing insulin resistance , diabetes , and inflammation . tryptophan ( trp ) exceeding basal requirement for protein synthesis is oxidized via indole - ring cleavage through the kynurenine pathway , consisting of several enzymatic reactions leading to 2 - amino 3 - carboxymuconate 6 - semialdehyde ( acms ) . acms can be decarboxylated to 2 - aminomuconate 6 - semialdehyde ( ams ) by the enzyme acms decarboxylase ( acmsd ) , or it can undergo spontaneous pyridine ring closure to form quinolinate , an essential precursor for de novo nad synthesis . ams can be converted nonenzymatically to picolinic acid ( pa ) or routed to the citric acid cycle via the glutarate pathway . trp catabolism , initiated by indoleamine 2,3 - dioxygenase ( ido ) , leads to the production of biologically active molecules . interferon - has been shown to be a potent stimulating cytokine for ido in vitro . similarly in vivo , a decrease in serum tryptophan and an increase in kynurenine in parallel were exhibited , indicating an enhanced degradation of tryptophan , while the cellular immune system is activated . in particular , the ratio of kynurenine to tryptophan ( kyn / trp ) seems to be a sensitive indicator for interferon -- induced tryptophan degradation ( reviewed in ) . the role of the tryptophan , particularly during inflammation , is just beginning to be appreciated , and a great deal of recent research has focused on the effects of tryptophan catabolites on effectors cell function . trp catabolites , biologically active molecules , represent a relatively newly identified class of stimuli , which differ from classical immunological stimuli because of their capability to signal to the macrophages through mechanisms that do not require a cell - surface receptor . among them , picolinic acid ( pa ) , a terminal metabolite of tryptophan degradation detected in vivo in human sepsis and in the serum of patients with liver cirrhosis , is capable of triggering mouse macrophages production of a number of inflammatory gene products , such as reactive nitrogen intermediates and cytokine . furthermore , trp - derived catabolites have been detected in vivo in patients with viral infections , malignant and inflammatory diseases . the results of numerous studies strongly suggest that macrophage activation seems to be a feature of chronic liver diseases . however , other studies have suggested a role for trp - derived catabolizes in macrophages activation . the rationale for seeking increased pa formation in chronic viral hepatitis is based on the involvement of activated macrophages in chronic viral hepatitis - associated inflammation . elevated formation of pa in patients with chronic hepatitis c infection might be expected due to enhanced trp breakdown demonstrated in inflammatory reactions . the aim of this study was to determine serum pa levels in patients with chronic hepatitis c infection , taking into account the presence of diabetes . this study was performed in 51 patients with chronic hepatitis c infection ( chc ) admitted to the clinic of infectious diseases , liver diseases and acquired immune deficiency for evaluation . the control group consisted of healthy blood donors with normal aminotransferases , normal blood counts , and negative markers for virus hepatitis and hiv ( 23 males / 17 females , median age 32.5 years , range 1965 years ) . no statistically significant difference between the chc patients and healthy controls in female / male ratio ( p = 0.51 ) was found . there was a significant difference in age , but pa level was not age related in neither the controls ( r = 0.14 , p 0.21 ) nor the chc patients ( r = 0.17 , p 0.34 ) . clinical and biochemical characteristics of the study group are reported in detail in table 1 . the exclusion criteria were as follows : ( 1 ) liver cirrhosis ; ( 2 ) conditions other than diabetes and hcv infection that could influence either serum glucose levels : premenopausal women ; alcohol consumption 40 g / day ; treatment with steroid or no steroidal anti - inflammatory drugs , except aspirin ; concomitant infection ; chronic diseases other than diabetes ; ( 3 ) type 1 diabetes ( history of diabetic ketoacidosis or age 30 years with insulin requirement ) and secondary diabetes due to chronic pancreatitis or pancreatic tumor . liver cirrhosis was ruled out by liver biopsy performed within 18 months before inclusion ( compensated patients ) or by typical clinical features such as signs of portal hypertension ( splenomegaly , ascites , and esophageal varies ) , hematologic evidence of hypersplenism , or biochemical evidence of hepatocellular failure . the diagnosis of chronic hepatitis c infection was based on persistently increased alanine aminotransferase values , anti - hcv and hcv - rna positivity , and liver histology features . the hcv inflammation was confirmed by measurement of hcv ab and hcv rna in the serum , using the eia methods and rt pcr - cobas amplicor roche methods , respectively . for the anti - hcv - positive patients with normal aminotransferase levels and no liver biopsy , we ensured that aminotransferase levels and liver function tests results were persistently normal . patients were divided in two groups according to their hcv antibody status and the presence of diabetes : anti - hcv - positive diabetic patients ( n = 22 ) and anti - hcv - positive nondiabetic patients ( n = 29 ) . diabetes was defined on the basis of a history of therapy with oral hypoglycemic agents or insulin at the time of inclusion . based on the clinical information , all diabetic patients in this study were assumed to have type 2 diabetes mellitus . we also evaluated 34 chc patients with cirrhosis and an additional group of 12 patients with chronic hepatitis b infection . the diagnosis of liver cirrhosis was based on clinical , laboratory , and ultrasonographic findings or histological criteria . three biochemical variables [ serum albumin , bilirubin , and prothrombin time ( international normalized ratio , inr ) ] in addition to the two clinical characteristics ( presence or absence of ascites and clinical signs of encephalopathy ) determine the child - pugh score . patients were scored as follows : 56 as class ( group ) a , 79 as class ( group ) b , and 1015 as class ( group ) c. the hbv infection was confirmed by measurement of the following infection markers in the blood serum : hbsag , hbeag , hbcab , hbeab - meia methods , abbotts imx , and hbv dna - digene hybrid capture . the consent of the bioethics committee of the wroclaw medical university was obtained , and all patients were informed about the character of analyses made . studies were conducted in compliance with the ethical standards formulated in the helsinki declaration of 1975 ( revised in 1983 ) . peripheral venous blood from fasted healthy subjects and fasted chc patients was collected in separate tubes , one containing the anticoagulant ethylenediamine tetraacetic acid and the other without serum anticoagulant . the blood was allowed to clot for 30 min at 25c and centrifuged at 2000 g for 15 min at room temperature , and the serum was then separated and aliquoted into tubes for storage . the tubes were stored frozen at 80c until they were used to study different parameters . serum crp levels were determined with a high - sensitivity nephelometric method using the beckman image immunochemistry system ( beckman instruments , fullerton , ca ) , which has a minimum level of detection of 0.2 mg / l . the intra - and interassay coefficients of variation for measurements of crp were 2.7 % and 3.0 % , respectively . the concentrations of serum trp , kyn , and pa in patients with chc ( n = 51 ) were determined by high - performance liquid chromatography ( hplc ) ( 22 ) , and the content ratios of kyn to trp ( kyn / trp ) were calculated . in brief , a waters model 2690 ( milford , ma , usa ) was used . sample injection was controlled by a millennium 32 data system , and a 100l loading loop was used . tryptophan was detected with a fluorescence detector ( waters 474 scanning fluorescence detector ) at an excitation wavelength of 285 nm and an emission wavelength of 360 nm ; kynurenine was detected by a uv detector ( waters 2487 dual delta absorbance detector ) at a wavelength of 360 nm , and picolinic acid was detected by the same uv detector at a wavelength of 265 nm . an array detector ( waters 996 photodiode array detector ) was used for the identification of the peaks . to control the setup and for peak quantification , borwin and ms excelbriefly , before each hplc analysis , we used acid precipitation to dissociate the putative pa - protein complexes and to extract the samples . every sample was spiked with methyl - dl tryptophan ( as an internal standard ) before the acid precipitation . blood serum was adjusted to a final concentration of cold 2 % perchloric acid and kept on ice for 30 min . samples were centrifuged at 13000 g for 6 min at room temperature to precipitate and separate the protein . supernatant was neutralized by adjusting to 0.4 m potassium hydroxide , filtered through a 0.45 m filter ( 13 mm ghp 0.45 mm minispike from waters ) , and analyzed by hplc . for chromatographic separation , we used the symmetry shield rp18 column ( waters ) and the symmetry shield rp18 precolumn ( waters ) to protect the column . after a chromatographic session was completed , once per day the system was rinsed with a gradient to / from pure methanol , and the precolumn was replaced . the identification of tryptophan catabolites was achieved by comparing the retention times and spectral data ( obtained by diode - array detection ) with the standard and by spiking the samples with pa , kyn , and trp . calibration curves were fitted by linear least - square regression and correlated with the concentration of methyl - dl tryptophan . finally , the kynurenine - to - tryptophan ( kyn / trp ) ratio was calculated dividing kynurenine concentrations ( mol / l ) by tryptophan concentrations ( mol / l ) . the precision of the method was estimated by measuring the pa at four different concentrations . the intraday and interday variations were determined by spiking with pa in triplicate runs 2 times within 1 day and in at least 1 run per day for 6 days . frequency data were compared using the test or the fischer 's exact test when necessary . because many of the variables analyzed did not have a normal distribution as determined by the kolmogorov - smirnov test , nonparametric tests were used for comparison of data . the mann - whitney u test and the kruskal - wallis testmultiple regression analysis was conducted by a stepwise model ( with p 0.05 as an entrance criterion and p 0.1 as a removal criterion ) . variables found to significantly correlate with pa in bivariate analysis were introduced into the model as explanatory variables ( wbc , hscrp , and the presence of diabetes in all subjects or in diabetic chc patients ) . regression analysis to determine significant correlations among different parameters was performed using the spearman correlation coefficient . we analyzed 51 patients ( 23 males / 17 females , median age 46 years , range 1865 years ) with chronic hepatitis c infection ( chc ) . the distribution of the stages of liver cirrhosis as defined according to the child - pugh score and measurements of tryptophan ( trp ) and catabolites serum concentrations are presented in figure 1 . trp and catabolites were also checked for correlations with selected biochemical markers of liver function ( albumin , prothrombin ratio , and bilirubin concentration ) and injury ( aminotransferases ) . the concentration of trp was measured in all 51 patients with chc with a median of 65.8 mol / l ( range 53.877.4 mol / l ) ( figure 1 ( a ) ) . in healthy controls , serum trp in chc patients without cirrhosis was only slightly reduced compared with that in other groups . however , trp levels were unchanged in chc patients with cirrhosis ( n = 34 ) ( figure 1 ( a ) ) . unexpectedly , all chc patients had lower kynurenine levels in their serum than healthy controls ( figure 1 ( b ) ) . the kynurenine to tryptophan ( kyn / trp ) ratio in chc patients was slightly lower than that of the controls , but this difference was not statistically significant ( 0.0440.02 versus 0.0460.05 ; p = 0.11 ) . serum kyn levels were significantly lower in chc patients with cirrhosis than those measured in healthy controls . however , in patients with child - pugh class a cirrhosis , the serum kyn was similar to that in healthy controls ( figure 1 ( b ) ) . the relatively small number of subjects in this group is insufficient to draw a meaningful conclusion ( n = 9 ) . there was no significant difference in kyn levels between the child - pugh class a and child - pugh class c cirrhotic patients . the peculiarity of chc patients is the reduction in serum trp associated with reduced serum kyn levels . the importance of such metabolic changes in the overall clinical picture remains to be studied in detail . picolinic acid ( pa ) serum concentrations were significantly higher in chc patients than in healthy controls ( controls median 0.2 mol / l range 0.21.8 mol / l , p 0.01 ) . serum pa concentrations were higher in child - pugh class a to class c cirrhotic patients ( n = 34 , median 2.1 mol / l , range 0.229.2 mol / l ) than in patients without cirrhosis ( n = 51 , median 1.7 mol / l , range 0.26.7 mol / l ) , but this difference was not statistically significant ( figure 1 ( c ) ) . the levels of serum pa in all cirrhotic patients were higher than those of healthy controls , and this difference was statistically significant ( p 0.01 ) ( figure 1 ( c ) ) . the levels of serum pa in patients with child - pugh class c cirrhosis were higher than those in child - pugh class a cirrhosis , but this difference was not statistically significant ( p = 0.17 ) ( figure 1 ( c ) ) . there was no statistically significant correlation between pa levels and the child - pugh score in cirrhotic patients . correlation analysis of trp , kyn , pa , and selected inflammatory markers revealed only a tendency toward an extremely weak but significant correlation between pa and hscrp in chc patients ( r = 0.23 , p 0.05 ) . no correlation was found between trp , kyn , pa and biochemical markers of liver function ( albumin , prothrombin ratio , and bilirubin concentration ) and injury ( aminotransferases ) . we failed to find any relation between the circulating levels of pa and trp , kyn , or kyn / trp ratio . differences in serum trp and kyn were not significant in both chronic hepatitis c and chronic hepatitis b infection . unfortunately , efforts to conduct studies in patients with chronic hepatitis b have been hampered by the fact that the majority of chronically infected persons do not develop symptoms and therefore do not seek medical attention ; consequently , the numbers included in the case series have been small . although we could not find an association between the serum concentration of pa and viral etiology of hepatitis ( table 2 ) , pa serum levels were considerably lower in the group with chronic hepatitis b infection ( n = 12 , median 1.02 mol / l , range 0.25.0 mol / l ) than in the group with chronic hepatitis c infection . these results are based on a small number of subjects , so the lower pa serum levels in this group should be viewed with caution . the demographic , biochemical , and clinical characteristics of healthy controls and chc patients both with and without diabetes are shown in table 3 . glucose and hba1c levels were higher in chc patients with diabetes than in chc patients without diabetes , and aminotransferase levels were higher in chc patients with and without diabetes than in the healthy controls . pa levels in chc patients with diabetes were higher than those in the other groups ( p 0.01 ) ( table 3 ) . in addition , when patients with normal aminotransferases were examined , the differences remained statistically significant ( data not shown ) . however , pa levels in nondiabetic chc patients were similar to those in the healthy controls . compared with the healthy controls , chc patients with diabetes showed a significant increase in serum concentrations of high - sensitivity c - reactive protein ( hscrp ) and white blood cell ( wbc ) counts ( table 3 ) . the levels of serum hscrp in diabetic chc patients were higher than those of the nondiabetic patients , and this difference was statistically significant ( p 0.01 ) . there were no differences in platelet ( plt ) counts and erythrocyte sedimentation rate ( esr ) between patients and healthy controls ( table 3 ) . the association study revealed only a tendency toward an extremely weak but significant correlation between pa and wbc in chc patients with diabetes ( r = 0.25 , p 0.05 ) . however , a moderate correlation between pa levels and hscrp was observed among the diabetic chc patients ( r = 0.43 , p 0.05 ) . using serum pa level of 3.14 mol / l as a cut - off value , the patients with chc were divided into two groups ( high or low levels of pa ) . the relationship between pa ( high or low levels ) and the other variables considered in the study in patients of the whole group ( chc patients with and without diabetes ) and chc patients without diabetes is shown in table 4 . in the whole group of patients , pa was related to the presence of diabetes and high levels of hscrp ( table 4 ) . however , when diabetic chc patients were excluded , the relationship between pa and hscrp disappeared ( table 4 ) . we found that from among the variables ( entered into the model , that is , wbc , hscrp , and the presence of diabetes ) , only hscrp exerted an independent effect on pa level in diabetic chc patients . this index alone accounted for 38 % of pa variance ( coefficient of determination : r = 0.38 ; multiple correlation coefficient : rm = 0.62 ; significance of the model : p 0.001 ) . for all chc patients , hscrp and the presence of diabetesthe regression model with these 2 variables explained 60 % of pa variance ( r = 0.60 ; rm = 0.76 , p 0.001 ) . to our knowledge , this is the first report of elevated pa concentrations in patients with chronic hepatitis c infection ( chc ) in which a relationship of pa to the inflammatory response has been demonstrated . previous studies demonstrated increased levels of picolinic acid in the serum of patients with chronic liver diseases , but in these studies confounding factors such as age distribution , severity of liver damage ( cirrhosis versus chronic hepatitis ) , or the presence of diabetes have not been taken into account . the net effects on markers of inflammation in chc patients are unknown . in the present study , we have examined the relationship between kyn pathway metabolism and inflammation by comparing both hscrp and white blood cell count in chc patients showing high levels of pa in the presence of low circulating kyn concentrations . after considering the confounding factors mentioned above , we provide evidence that the connection between pa and chronic inflammatory state is initiated at early stages of chronic viral hepatitis . inflammation is a major component of the pathogenesis of chronic hcv infection . in clinical studies , significant decreases in serum trp concentrations have been reported in patients with chronic inflammatory diseases such as hiv infection , malaria , and malignant and inflammatory bowel diseases ( reviewed in ) . enhanced breakdown of trp leading to the production of biologically active metabolites has been demonstrated in vivo under inflammatory conditions , during the rejection of transplanted tumors or in cancer patients treated with interferon - gamma ( ifn - ) , and the trp catabolite , picolinic acid ( pa ) , was found in the serum of patients with liver cirrhosis . the present finding that pa accumulation coexists with decreased levels of trp and the kyn / trp ratio supports the contention that flux through the kynurenine pathway is reduced in chc patients . the most plausible explanation for the results obtained is that downstream catabolism of quinolinic acid is reduced , thereby providing higher levels of the intermediate aminocarboxymuconate - semialdehyde ( acms ) for pa synthesis . picolinic acid as a macrophage secondary signal causes the activation of ifn -- prime macrophage and triggers cytokine - driven inflammatory reactions in vitro . on the other hand , the recruitment of circulating leukocytes to an inflammatory site in response to stimuli such as the hepatitis c virus is a crucial step in the development of chronic inflammatory responses . in these conditions , extravasation of circulating leukocytes requires communication with vascular endothelial cells that in turn depends on an interrelated network of events involving the proinflammatory cytokines ( i.e. , interleukin [ il ] - 1 , il - 6 , and tumor necrosis factor [ tnf ] - ) , adhesion molecules , and chemokines ( notably mip - 1 - and mip - 1 - ) . the experiments in cell showed that pa is an activator of the inflammatory chemokines macrophage - inflammatory - protein - ( mip - ) 1 - and mip - 1 - mrna expression macrophages through a novo protein synthesis - dependent process . thus , the very weak correlation between pa levels and inflammatory marker c - reactive protein ( hscrp ) may suggest an indirect contribution of pa to the maintenance of the inflammatory milieu through other mediators . finally , the values of pa in chc patients and normal aminotransferases suggest that pa might have a role in the early stages of chronic viral hepatitis by amplifying the chronic inflammatory state already caused by the hepatitis c virus . the association between tryptophan content and diabetes is supported by the observation that tryptophan levels are reduced in age - related metabolic disorders . the specific mechanisms that could lead to pa enhancement in chc patients with diabetes remain to be explained . it is possible to speculate that elevated levels of pa may occur as a result of increased activity of the enzyme responsible for the synthesis of pa . acmsd ( picolinate carboxylase , 2 - amino 3 - carboxymuconate 6 - semialdehyde ( acms ) decarboxylase ; acmsd ) is a key enzyme directing kynurenine pathway metabolism towards pa production and is mainly present in liver , kidney , and brain tissue . one study showed that in liver of streptozotocin - induced diabetic rats , hepatic acmsd activity is increased markedly , and insulin injection suppresses this elevation . finally , our results showed that diabetes but not hcv infection was independently related to pa in patients with chronic hepatitis c infection . accumulating evidence suggests that chronic hepatitis c virus infection increases the risk of atherosclerotic cardiovascular disease by causing insulin resistance and diabetes . some research has suggested that hepatitis c virus may also trigger the release of proinflammatory cytokines such as tnf - , il - 6 , il - 1 , and inflammatory crp . the results of general population - based studies have also demonstrated a relationship between hepatitis c virus persistence and carotid atherosclerotic plaques and intima - media thickness . interestingly , this recent research suggests that active macrophage infiltration into the arterial wall induces the development of an early atherosclerotic lesion . on the other hand , as we mentioned above , pa is capable of activating macrophages and inducing the expression of the inflammatory chemokines mip - 1 and mip - 1 belong to the - chemokines family , which plays a key role in the recruitment of mononuclear cells ( monocytes and t lymphocytes ) into atherosclerotic lesions . together , our observations show that the simultaneous elevation of pa and hscrp levels in chc patients with diabetes suggest that their local tissue production is linked . this is in accordance with experimental data showing overexpression in plaques of both - chemokines as well as crp and may be due to global activation of cells that synthesize and secrete these molecules . even if the correlation between pa and wbc was extremely weak , we demonstrated clear association with inflammatory crp . finally , our results show that the elevation of pa was dependent on inflammation status because in diabetic chc patients with normal hscrp concentrations , pa level was not significantly elevated in comparison with healthy controls ( data not shown ) . although crp can merely be a marker of an underlying inflammatory process , it is possible that crp may be directly involved in the pathogenesis of inflammation / atherosclerosis . in this context , the association between picolinic acid and the presence of inflammation in chc patients with diabetes could represent one of the mechanisms involved in atherosclerotic process in this population . firstly , the small set of 51 patients included in this study may have resulted in limited power to discriminate between categories and levels of exposure . secondly , the part of our patients , categorized aschc patients without diabetes may have diabetes without symptoms , and many of them may develop diabetes in the future . finally , because of its cross - sectional nature , this study is limited in terms of deriving mechanistic conclusions ; however , results of this study are hypothesis generating and provide insights into the relationship between pa levels and inflammatory response and the presence of diabetes in patients with chc . in conclusion , we have documented significant elevation in serum levels of pa in patients with chc . in addition , circulating pa was associated with inflammatory marker crp and the presence of diabetes , but not with markers of liver injury aminotransferases . in summary , our results provide further evidence for the presence of high levels of hscrp in chc patients with diabetes , and we propose a role for pa in this context . the results of our study should be interpreted as trends to be confirmed by further studies with larger sample size .\noutput:\n" }, { "from": "agent", "value": "macrophage activation seems to be a feature of chronic liver diseases . picolinic acid ( pa ) as a macrophage secondary signal causes the activation of interferon - gamma - ( ifn -- ) prime macrophage and triggers cytokine - driven inflammatory reactions . the rationale for seeking increased pa formation in chronic viral hepatitis is based on the involvement of activated macrophages in chronic viral hepatitis - associated inflammation . the aim of this study was to determine serum pa levels in patients with chronic hepatitis c infection , taking into account the presence of diabetes . we assessed pa and high - sensitivity c - reactive protein ( hscrp ) as a marker of inflammation in 51 patients with chronic hepatitis c infection ( chc ) , both with and without diabetes and 40 controls . compared with the controls , the patients with chc showed a significant increase in plasma concentrations of pa and hscrp ( p < 0.01 and p < 0.05 , resp . ) . the values of pa and hscrp were more elevated in patients with diabetes than without diabetes ( both p < 0.01 ) . the positive relationships were between pa and hscrp levels ( p < 0.05 ) and the presence of diabetes ( p < 0.001 ) . we documented that significant elevation in serum pa levels is associated with diabetes prevalence and increased inflammatory response reflected in hscrp levels in chc patients ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: splenic angiosarcoma is a rare tumor with only a few cases reported in the literature . surgical resection offers the best chance of cure for this aggressive neoplasm but is often precluded by infiltration of the tumor to surrounding critical structures . we report a case of a locally advanced angiosarcoma rendered operable by treatment with paclitaxel monotherapy . a 69 year old female presented with a high grade splenic angiosarcoma , considered inoperable due to the extent of local spread . she received three cycles of single agent paclitaxel and underwent a successful resection of the tumor . paclitaxel as monotherapy is a useful therapeutic option in down staging tumors , facilitating surgical resection and merits further study in clinical trials . splenic angiosarcomas are exceedingly rare tumors with a very poor prognosis .1 only a few cases have been reported in the literature , since its original description by langhans in 1879.2 angiosarcomas have a highly variable histology and can be mistaken for vascular benign tumors or other non vascular malignant neoplasms . on microscopy most of them have a well defined nodular homogenous appearance and all of them show a vasoformative component . most of the tumors express at least one immunohistochemical marker of histiocytic differentiation ( cd68 and / or lysozyme ) and two or more markers of vascular differentiation ( cd 34 , cd31 , fviii r ag , vegfr3 ) .3 on radiological imaging , these tumors show an enlarged spleen ( 12 cm ) , usually with either a solitary complex mass or multiple diffusely infiltrative heterogeneous masses .4 metastases are a frequent finding at the time of diagnosis with up to 70 % of metastatic deposits involving the liver . common sites of metastatic disease include lung followed by bone and liver .5 low platelet counts are seen in 33 % of splenic angiosarcoma cases , which should be considered in the differential diagnosis of unexplained thrombocytopenia .6 in a retrospective study of 82 angiosarcoma patients , those with a primary resectable tumor had a 5 year disease specific survival ( dss ) rate of 60 % . sixty seven percent of these patients received adjuvant radiation and 27 % received chemotherapy . tumors with intermediate or high grade pathology ( 76 % ) and those arising from previously irradiated or lymphedematous areas had worse disease specific survival .7 in another study looking at patients with advanced angiosarcomas , median disease - specific survival ( dss ) for patients with locally recurrent disease and metastatic disease was 50 months ( 95 % confidence interval ( ci ) : 25.773.5 months ) and 10 months ( 95 % ci : 7.912 months ) respectively .8 most of these studies included patients with angiosarcomas arising from various sites including soft tissues , breast , skin , viscera and bone . due to a paucity of data , it is however unclear if splenic angiosarcomas have a different natural course of progression than sarcomas arising from other organs . several chemotherapy treatment options have been tried in patients with locally recurrent / metastatic angiosarcoma , including paclitaxel gemcitabine , doxorubicin ifosfamide , docetaxel gemcitabine ,9 interferon alfa , dacarbazine , bevacizumab , etoposide , cisplatin and various combinations of these agents .10 paclitaxel is an alkaloid ester extracted from the bark of the pacific yew tree ( taxus brevifolia ) and the european yew tree ( taxus baccata ) .11 it stabilizes the microtubules by inhibiting the process of tubular depolymerization .12 this process occurs during the metaphase / anaphase transition of the mitotic cell cycle , resulting in an arrest of cell division .13 it also demonstrates antiangiogenic activity by inhibiting endothelial cell proliferation , motility and invasiveness , both in vivo and in vitro .14 in a phase ii study of paclitaxel therapy in advanced soft tissue sarcoma ,15 a complete response was seen in a patient with angiosarcoma of the scalp . a retrospective study of patients with angiosarcoma of the scalp has shown that paclitaxel is effective in the treatment of angiosarcoma of the scalp16 with a major response ( complete response + partial response ) seen in 8 out of 9 ( 89 % ) patients . a further phase ii clinical trial of paclitaxel in advanced angiosarcoma suggested that weekly paclitaxel is well tolerated and is associated with a progression free survival rates of 74 % and 45 % at 2 months and 4 months respectively .17 at a median follow up of 8 months the study reported a progression free survival of 4 months and a median overall survival of 8 months . here we present a patient with locally advanced splenic angiosarcoma treated with single agent with neo - adjuvant paclitaxel . based on an extensive search of the available literature , we believe this is the first report of paclitaxel facilitating surgical resection in locally advanced splenic angiosarcoma . a 69 year old caucasian female presented to us with a 4 month history of pain in the left upper quadrant of the abdomen , associated with a 30 lb weight loss and progressive shortness of breath . a ct scan of the chest , abdomen and pelvis revealed an enlarged spleen containing multiple heterogeneous hypodense masses , extending through the capsule into the peritoneal cavity , left anterolateral abdominal wall , left retrocrural space , and invading the left hemidiaphragm with the presence of at least 2 soft tissue implants superior to the left hemidiaphragm . an mri scan of the brain and an isotope bone scan were performed to stage her disease but no metastatic disease was identified . she was assessed for surgery , but the tumor was considered too extensive for a surgical resection . she was then offered chemotherapy for down staging the tumor , and though there was no precedence for its usage in splenic angiosarcomas , paclitaxel was chosen in view of its established efficacy in other locally advanced , unresectable soft tissue sarcomas . she received a total of three cycles of paclitaxel at a dose of 175 mg / m every three weeks , the most frequently used dose schedule in a retrospective review of nine patients with angiosarcoma of the face and scalp .16 she experienced grade 2 tiredness and neutropenia but otherwise remained free of systemic toxicity . a repeat ct of the chest abdomen and pelvis after the third cycle of chemotherapy showed a 33 % decrease in the tumor size , indicating a partial response as per recist criteria .18 there was also a complete resolution of her left hemidiaphragmatic tumor implants along with the left sided pleural effusion . a splenectomy was then performed along with a resection of the left hemidiaphragm followed by a graft repair of the diaphragm . pathological examination of the resected specimen showed areas of extensive necrosis and also confirmed that her splenic angiosarcoma was completely resected , with clear margins ( figs . 1 and 2 ) . also , no tumor extension was seen in 12 regional lymph nodes that were resected during surgery . she was discharged home after a short , uneventful postoperative stay in the surgical intensive care unit . following a four week break to allow recuperation from surgery , she was restarted on paclitaxel and has received a further three cycles of adjuvant therapy without any significant toxicity . she continues to remain well at the time of this report , 14 months following the initiation of her chemotherapy . the propensity of the tumor to disseminate locally and its proximity to critical intra - abdominal structures often precludes surgery at presentation . chemotherapy is often used to downstage locally advanced angiosarcomas to improve respectability , but data on the efficacy of available therapeutic agents is limited . treatment with paclitaxel based regimes is shown to predict better dss with a trend towards statistical significance ( hr : 0.67 , p = 0.06 ) .8 paclitaxel had also been shown to achieve high rates of objective response in patients with kaposi s sarcoma , another vascular tumor , commonly seen in the immunocompromised individuals .19 paclitaxel is a generally well tolerated drug and can be used even in patients with a relatively modest performance status . the proximity of splenic angiosarcomas to the kidneys often causes ureteric obstruction resulting in renal impairment . renal clearance of paclitaxel and its metabolites is minimal and accounts only for less than 10 % of the excretion of the drug .20 though a three weekly regime is the commonest schedule of administration of this drug , studies attempting to increase the dose intensity by more frequent administration of the drug have shown such regimes to be well tolerated , simultaneously achieving good response rates .17,21 however , there are no comparative studies of the various dosing regimes to guide therapy at this stage , making it difficult to choose between the various available scheduling options . these factors would make paclitaxel a strong choice for the management of splenic angiosarcomas . our report shows that paclitaxel can be administered safely and effectively in the patients with locally advanced splenic angiosarcoma , and renders the tumor highly resectable . further randomized studies are required to define the role of paclitaxel in comparison to other chemotherapeutic agents and also to determine its ideal dose schedule , in the treatment of visceral angiosarcomas .\noutput:\n" }, { "from": "agent", "value": "introduction : splenic angiosarcoma is a rare tumor with only a few cases reported in the literature . surgical resection offers the best chance of cure for this aggressive neoplasm but is often precluded by infiltration of the tumor to surrounding critical structures . we report a case of a locally advanced angiosarcoma rendered operable by treatment with paclitaxel monotherapy.case presentation : a 69 year old female presented with a high grade splenic angiosarcoma , considered inoperable due to the extent of local spread . she received three cycles of single agent paclitaxel and underwent a successful resection of the tumor.conclusion : chemotherapy options for splenic angiosarcoma are not well studied . paclitaxel as monotherapy is a useful therapeutic option in down staging tumors , facilitating surgical resection and merits further study in clinical trials ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: lentinula edodes strains were collected from various sources and maintained at the korea forest research institute ( kfri ) , seoul , korea . the selected shiitake strains ( dikaryons , kfri 36 , 38 , 57 , 58 , 59 , 171 , 182 , 183 , 192 , 193 , 194 ) were bred with monokaryons ( kfri 535 , 536 ) , which were isolated from the spores of the kfri 405 fruiting body . the newly bred shiitake strains were obtained by di - mon breeding method ( table 1 ) . trichoderma spp . , were isolated from kfri shiitake cultivation and five strains were used in this experiments . all of the fungal cultures were incubated on potato dextrose agar ( pda , gellix , korea ) at 23 for 10 days and used as inoculum . competitive interactions between shiitake and mycoparasitic fungi were studied in dual - culture experiments on a pda in vitro system . in each experiment , 5 mm diameter mycelial disks , which transferred to the shiitake and trichoderma spp . the shiitake inoculum were prepared 7 days before trichoderma inoculation because of its stabilization before trichoderma 's attack . the shiitake - trichoderma paired in all possible combinations and five replicates were carried out all the experiments . the fungal cultures were incubated at 23 and measured their invading zone , after 7 and 30 days later . the invading zone were divided into 5 types as follow : no resistant activity , l. edodes was completely invaded by trichoderma spp . ; stop growing after mycelial contact and formed strong antithetic zone line ; weakly resistant , l. edodes partially overgrew the territory of trichoderma spp . inoculation site ; strong resistant , l. edodes completely overgrew the territory of trichoderma spp . to observe antagonistic action of l. edodes on trichoderma spp . after 1 month of incubation , a strong antithetic line was formed on the agar . the interacting zones between l. edodes and trichoderma spp . were cut and prepared for scanning electron microscopic observation ( jacob et al . , 1996 ) . lentinula edodes strains were collected from various sources and maintained at the korea forest research institute ( kfri ) , seoul , korea . the selected shiitake strains ( dikaryons , kfri 36 , 38 , 57 , 58 , 59 , 171 , 182 , 183 , 192 , 193 , 194 ) were bred with monokaryons ( kfri 535 , 536 ) , which were isolated from the spores of the kfri 405 fruiting body . the newly bred shiitake strains were obtained by di - mon breeding method ( table 1 ) . trichoderma spp . , were isolated from kfri shiitake cultivation and five strains were used in this experiments . all of the fungal cultures were incubated on potato dextrose agar ( pda , gellix , korea ) at 23 for 10 days and used as inoculum . competitive interactions between shiitake and mycoparasitic fungi were studied in dual - culture experiments on a pda in vitro system . in each experiment , 5 mm diameter mycelial disks , which transferred to the shiitake and trichoderma spp . the shiitake inoculum were prepared 7 days before trichoderma inoculation because of its stabilization before trichoderma 's attack . the shiitake - trichoderma paired in all possible combinations and five replicates were carried out all the experiments . the fungal cultures were incubated at 23 and measured their invading zone , after 7 and 30 days later . the invading zone were divided into 5 types as follow : no resistant activity , l. edodes was completely invaded by trichoderma spp . ; stop growing after mycelial contact and formed strong antithetic zone line ; weakly resistant , l. edodes partially overgrew the territory of trichoderma spp . ; inoculation site ; strong resistant , l. edodes completely overgrew the territory of trichoderma spp . after 1 month of incubation , a strong antithetic line was formed on the agar . the interacting zones between l. edodes and trichoderma spp . were cut and prepared for scanning electron microscopic observation ( jacob et al . , 1996 ) . among 11 l. edodes strains , only 4 ( kfri 36 , 38 , 58 , 171 ) were resistant to trichoderma harzianum ( table 2 ) . at the initial time of incubation , after one month , l. edodes was partially or completely invaded by trichoderma spp . in most pairings ( fig .1 ) . however , kfri 36 , 38 , 58 , 171 showed resistance to t. harzianum and overgrew the territory of mycoparasitic fungi . kfri 171 also showed resistance to one of t. atroviride strains . kfri 58 had a similar competitive activity against trichoderma spp . they stopped growing with the formation of strong antithetic zone lines with t. harzianum and t. atroviride after one month . these resistant strains need to be studied further in bedlog culture and then might be used for greenmold disease resistant strains . these antifungal activities may be increased their resistant activities against some mushroom pathogenic fungi , for example trichoderma spp . the understanding of these particular interaction may be a useful key to the control of greenmold disease during shiitake cultivation and needs further investigation . thirteen hybrid shiitake strains were bred by di - mon breeding method ( table 1 ) . most of the hybrid strains formed deadlock or invading zone at the initial time of incubation , like their parent strains . among them , only 5 strains showed resistant to trichoderma spp . kfri 57 - 1 and 59 - 1 had resistance activity against t. reesei and t. harzianum , respectively . however , kfri 38 - 1 , 38 - 2 and 36 - 1 lost the resistance activity of their parent strains against t. harzianum . kfri 58 - 1 had resistance activity against t. atroviride but lost their resistance activity against t. harzianum , compared to their parent strains . these results may be associated with insertion of foreign genes of monokaryons derived from basidiospores . on breeding of shiitake strains resistant to trichoderma spp . , tokimoto and komatsu ( 1995 ) observed that the resistance was revealed dominantly . however , in the new hybrid strains of l. edodes in our study , resistance to trichoderma spp . was not dominant inherited . the mechanism of these resistant gene transfers might be the key in making resistant strains and needs further investigation . in the interaction zone between l. edodes and trichoderma spp . , the hyphal cell of l. edodes was distorted with local swellings and was inhibited by trichoderma spp . in untreated l. edodes , reper and penninckx ( 1987 ) observed that mycoparasitic fungus affected the growth of p. ostreatus mainly by producing a volatile toxin which killed p. ostreatus . in our study , mechanically by forming brown barrages in the antithetic zone line . through sem observation , we determined that the hyphal cells of antithetic zone line were swollen and thickened . this could be associated with the formation of melanin compounds that protect hyphal cells , making them resistant to mycoparasitic fungi attack . some studies suggest that melanin formation is part of a defensive response against mycelial invasion and that these compounds help fungi to adapt to environmental stress ( rayne et al . , 1994 ; badalyan et al . ,2004 ) . these could be associated with release of volatile and non - volatile metabolites produced by trichoderma spp . among 11 l. edodes strains , only 4 ( kfri 36 , 38 , 58 , 171 ) were resistant to trichoderma harzianum ( table 2 ) . at the initial time of incubation , after one month , l. edodes was partially or completely invaded by trichoderma spp . in most pairings ( fig .1 ) . however , kfri 36 , 38 , 58 , 171 showed resistance to t. harzianum and overgrew the territory of mycoparasitic fungi . kfri 171 also showed resistance to one of t. atroviride strains . kfri 58 had a similar competitive activity against trichoderma spp . they stopped growing with the formation of strong antithetic zone lines with t. harzianum and t. atroviride after one month . these resistant strains need to be studied further in bedlog culture and then might be used for greenmold disease resistant strains . these antifungal activities may be increased their resistant activities against some mushroom pathogenic fungi , for example trichoderma spp . the understanding of these particular interaction may be a useful key to the control of greenmold disease during shiitake cultivation and needs further investigation . thirteen hybrid shiitake strains were bred by di - mon breeding method ( table 1 ) . most of the hybrid strains formed deadlock or invading zone at the initial time of incubation , like their parent strains . among them , only 5 strains showed resistant to trichoderma spp . kfri 57 - 1 and 59 - 1 had resistance activity against t. reesei and t. harzianum , respectively . however , kfri 38 - 1 , 38 - 2 and 36 - 1 lost the resistance activity of their parent strains against t. harzianum . kfri 58 - 1 had resistance activity against t. atroviride but lost their resistance activity against t. harzianum , compared to their parent strains . these results may be associated with insertion of foreign genes of monokaryons derived from basidiospores . on breeding of shiitake strains resistant to trichoderma spp . , tokimoto and komatsu ( 1995 ) observed that the resistance was revealed dominantly . however , in the new hybrid strains of l. edodes in our study , resistance to trichoderma spp . was not dominant inherited . the mechanism of these resistant gene transfers might be the key in making resistant strains and needs further investigation . in the interaction zone between l. edodes and trichoderma spp . , the hyphal cell of l. edodes was distorted with local swellings and was inhibited by trichoderma spp . in untreated l. edodes , reper and penninckx ( 1987 ) observed that mycoparasitic fungus affected the growth of p. ostreatus mainly by producing a volatile toxin which killed p. ostreatus . in our study , mechanically by forming brown barrages in the antithetic zone line . through sem observation , we determined that the hyphal cells of antithetic zone line were swollen and thickened . this could be associated with the formation of melanin compounds that protect hyphal cells , making them resistant to mycoparasitic fungi attack . some studies suggest that melanin formation is part of a defensive response against mycelial invasion and that these compounds help fungi to adapt to environmental stress ( rayne et al . , 1994 ; badalyan et al . , these could be associated with release of volatile and non - volatile metabolites produced by trichoderma spp .\noutput:\n" }, { "from": "agent", "value": "trichoderma spp . cause large crop losses of the cultivated shiitake mushroom , lentinula edodes . we bred several shiitake strains that are resistant to trichoderma spp . using di - mon mating to establish a useful method for controlling the greenmold disease . we examined the competitive ability of l. edodes against trichoderma spp . using a dual culture system to select resistant strains . by screening trichoderma - resistant strains , we found that among 11 parental strains , 4 strains , including kfri 36 , were confirmed resistant strains . they showed especially strong resistance to t. harzianum , which formed deadlock after mycelial contact and then invaded into the territory of t. harzianum . kfri 171 also showed resistance to t. atroviride strains . among 13 strains , which were made by hybridization of shiitake strains , 5 were confirmed to be resistant to trichoderma , including kfri 58 - 1 . their resistance was not correlated to the resistant activity of their parents ' strains . two strains lose resistance and two strains acquire resistance compared to their parents ' strains . in sem observation , the mycelium of l. edodes at the interaction zone of lentinula - trichoderma was rugged and swollen by t. harzianum ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: complexity of a human biological system typically allows its relations to be expressed only in a nonlinear way . because of this complexitydiabetes mellitus is a metabolic disorder of endogenous insulin allowing excessive amount of glucose to stay in blood . in general , blood glucose is transformed into energy required by human activities , such as , walking , and this transformation requires insulin functionality . however , in diabetes mellitus , since a human body fully or partially lacks the insulin functionality , unchanged glucose remains in blood . a condition of high blood glucose profiles results in several complications , such as , eye , kidney , and nerve damage , called hyperglycemia . thus , in order to avoid the hyperglycemia , a continuous supply of exogenous insulin is required , and the insulin - dependent diabetic therapy usually does this . on the contrary , too much insulin supply may lead to a condition of low blood glucose profiles resulting in drowsiness , mental malfunctioning , irritability , and loss of consciousness . thus , the insulin - dependent diabetic therapy must concern both hyperglycemia and hypoglycemia by providing an appropriate amount of exogenous insulin timely . at the beginning of the insulin - dependent diabetic therapy , it is required to obtain an approximation of the insulin - glucose relation . two methods are taken in this process , namely , empirical and fundamental methods . arguably , this process is most time consuming . based on mathematical equations representing the insulin - glucose mechanism , broadly , controlling the blood glucose levels is achieved by means of three strategies , namely , open - loop , closed - loop , and partially closed - loop schemes . in general , the fully and partially closed - loop schemes involves several medical devices but the open - loop scheme does not . while in the closed - loop scheme , a system is aimed to completely encompass the diabetic , open - and partially closed - loop require the physician 's contribution to complete the loops . therefore , typically any decisions of the insulin injections are made by a physician in open - and partially closed - loop schemes . this paper is the second part of our survey of insulin - dependent diabetes . our first paper , the first part of the survey , mostly spent its pages on the background of insulin - dependent diabetes therapy , such as , description of type 1 and type 2 diabetes , the insulin functionality , and medical devices involved in the insulin - dependent therapy . in this paper , we survey blood glucose control schemes which lie on the basics of the insulin - dependent diabetes therapies and systems . the rest of the paper is organized as follows . in section 2 , we briefly summarize diabetes mellitus for the sake of induction to the topic . in section 3 , we explain empirical and fundamental schemes to derive mathematical models of the insulin - glucose dynamics . from sections 4 through 6 , we explore the control strategies , especially for the insulin - glucose dynamics . in these sections , we provide several applications based on the controls . the world health organization ( who ) reported that there were currently nearly 180 million patients suffering from diabetes allover the world , and the number of the diabetics would increase more than 350 million people by 2030 . from the same report , approximately 1.1 million people died from diabetes in 2005 and among this number , people under 70 years old account for a half . in the united states , currently it costs 136 billion dollars annually to take care of 12 million diabetes patients . in general , diabetes is considered as a condition that disproportionately affects developed countries . diabetes first emerged around 2000 b.c . while insulin and its functionality were discovered in 1921 . since the discovery of insulin , insulin - dependent diabetes therapies mostly concern how to delay the emergence of the complications in use of insulin supplement . in short , diabetes is characterized in a condition that blood keeps high glucose levels unchanged into energy resulting in several complications . although insulin is largely concerned with this reaction , diabetes fully or partially lacks this functionality . diabetes eventually causes cardiovascular disease , chronic renal failure , retinal damage , nerve damage , and microvascular damage . besides , according to characteristics of diabetes , it is typically classified into two types , namely , type 1 and type 2 diabetes . in short , in type 1 diabetes , from the malfunction of the pancreas resulting from the destruction of the cells of the islets of langerhans , a supply of endogenous insulin completely stops . otherwise , the diabetic eventually falls into a condition of hyperglycemia . on the other hand , in type 2 diabetes , the insulin functionality gradually weakens , but does not completely stops . since the diabeticmore or less has the endogenous insulin supply , diabetes therapies mostly focus on exercises or regimens consuming or suppressing excessive glucose in blood . however , both type 1 diabetes and type 2 diabetes are considered chronic and currently incurable . as mentioned beforethis is caused by the malfunction of the pancreas destroying the cells which are responsible for the endogenous insulin supply . it is considered a reason why the destruction of the cells occurs is due to the immune system which should react an infection by viruses , such as , the coxsackie virus family or german measles but mistakenly destroys the cells . type 1 diabetes is sometimes called childhood , juvenile or insulin - dependent diabetes although it does not only emerge during a childhood . on the other hand , type 2 diabetes does not stop the endogenous insulin supply , but instead it is characterized in insulin resistance , insulin deficiency , and hyperglycemia . although in type 2 diabetes , endogenous insulin still can facilitate its functionality , it is largely degraded and can not sufficiently change blood glucose into energy . thus , the amount of unchanged blood glucose will get larger resulting in hyperglycemia , a condition of high blood glucose profiles , causing eye , kidney , and nerve damage . however , since in the early stage of type 2 diabetes , the symptoms are not serious or noticeable , it is likely to miss its emergence easily . type 2 diabetes is sometimes inherited genetically , but in most of the cases it caused from irregular life styles , such as , the lack of exercise , obesity or a sedentary lifestyle . type 2 diabetes is also called non - insulin - dependent , obesity - related , or adult - onset diabetes . currently , diabetes can be treated at home by a patient himself or herself under the supervision of a physician . during the earlier years of the diabetes treatment , logs and tables of insulin injections and regimenswere kept , and according to these records next insulin injections and regimens as well as exercises are determined by a physician . now , microcontrollers and sensors enable autonomous insulin - dependent diabetes therapies systematically adjusting the insulin supply . more precisely , according to feedback from one or more blood glucose sensors , a rate of insulin supply of an insulin pump is determined , which works like an artificial pancreas . the advantages of an artificial pancreas are safe , automatic , and nonintrusive . several control schemes are developed in order to achieve the optimal exogenous insulin supply suppressing the blood glucose levels within a safe range of nominal . for more details about diabetes fundamentals , to procure the mathematical models of the human insulin - glucose system , several approaches are taken by researchers . in these approaches , these approaches aim to describe the insulin - glucose dynamics as a couple of mathematical equations that should be easy to manipulate for the insulin therapies and should fully describe the characteristics of the internal insulin - glucose metabolism . basically , the empirical method uses a model structure ( formula or equation ) which is determined theoretically with several parameters . the behavior of this model structure is determined by only the input - output data of the system from a number of experiments . in this method , capturing the system behavior or data is the most time - consuming process . in an example of the linear structure of the insulin - glucose system , to represent glucose effects , two parameters are used , and to represent insulin effects , other two parameters are also used in order to close the model to the actual system . in addition to the input - output data , semiempirical method utilizes other physiological factors , such as dynamic behavior and kinetics to create a closer model of diabetic patients . in the fundamental methods , a mathematical representation of the human internal system whichthis system behavior includes kinetics and material transport . according to investigating the internal system , a lot of data from the literature can be used to determine the system parameters . in particular , in constructing a fundamental diabetes model , the authors in applied the insulin - release data of the cells of the pancreas from a number of examinations to a mathematical representation . there are several classes of solutions to this problem , ranging in complexity , prerequisite knowledge , and feedback . the open - loop system for the insulin - dependent diabetes therapy does not employ any glucose sensors . however , occasionally calling the open - loop system is not appropriate and more precisely , the system should be called the programmed insulin infusion system because of its incomplete openness . that is , the control loop can be closed by the physician and the diabetic when interacting on the system . one example of the systems is one that was developed by case - western reserve university , and this system is considered to be one of the most intelligent programmed insulin infusion products that deal with the noninsulin - dependent diabetics . the idea is that from an analysis of the insulin curve in the nondiabetic , it was turned out that the curve approximately traces a combination of a double exponential curve and a basal insulin infusion . according to this mathematical model , an intravenous insulin delivery systemthe system utilized a portable cart containing the control system , the insulin - pump , power supplies , and insulin reservoir so that the patient could move around with the devices . the insulin pump delivers low - concentration insulin and updates the insulin delivery rate every 30 seconds . because of its simplicitythis research revealed the diabetics had the blood glucose profile to be improved considerably from a two - week examination , and , moreover , the improved conditions remained even several days after the examination . on the other hand , the researches of this programmed system so far did not indicate any hypocglycemic condition yet . in addition to the achievement of case - western reserve university , siemens and the finsen institute also developed a programmed insulin infusion system that employed a moderately complex delivery algorithm from another approach . the system is capable of manually inserting small pin connectors into the control unit in order to control the insulin delivery rate . like a product of case - western reserve university , the infusion rate follows an exponential curve , and the insulin infusion rate is updated every 30 minutes . the system to deliver insulin mechanically in order to regulate the glycemic profile is called the closed - loop system . as shown in figure 1 , the closed - loop system completes its operating cycle within the system and no external interaction to diabetic patients is required . in other words , the closed - loop control uses the feedback from the output . typically , the closed - loop system for type 1 diabetes therapy utilizes the glucose sensor and schematically consists of three phases : blood glucose measurements , insulin demand calculation , and insulin injection . so far , along with the glucose sensor , the closed - loop system also employs an insulin pump which continuously infuses insulin via a subcutaneous root . basically , insulin delivery is controlled by these implanted blood glucose sensors and an insulin pump attached to a patient 's body . in short , according to measurements of glucose level from an implanted blood glucose sensor , an insulin pump continuously infuses insulin into a patient 's body . however , although implanted blood glucose sensors benefit a lot for the diabetes therapy , establishing reliable measurements of blood glucose is so difficult that many researches in this field are still under way by many biomedical researchers . currently many forms of blood glucose sensors exist , such as fingerstick types , implantable types , or noninvasive types . for example , in applying a fingerstick - type blood glucose sensor , blood glucose levels are measured three to seven times a day and according to the measurements , the amount of insulin supply by an insulin pump is updated manually . however , since with the fingerstick - type sensors , measurements are carried out by patients themselves on regular basis , managing patient lifestyle by themselves is rather troublesome . meanwhile , when using an implantable blood glucose sensor , glucose levels in blood are automatically monitored in a certain amount of period . in calculating the insulin infusion , many control models are developed by researchers until now : pole - assignment strategy , self - tuning adaptive control , or nonlinear predictive control . pole assignment is a standard control systems technique for designing an infinite impulse response filter . this consists of a set of filter coefficients and a feedback loop in order to maintain a stable blood glucose level . in general , the closed - loop schemes of the insulin - dependent diabetes therapy utilize an insulin pump that automatically supplies insulin into the human body subcutaneously . usually the glucose levels are monitored by a needle - type glucose sensor through the subcutaneous ( sc ) route , and the insulin infusion rate ( iir ) is determined by continuous measurements of the blood glucose level . for example , in pole - assignment strategy , the iir in relation to blood glucose level , the insulin - glucose system , is determined by the following computation : ( 1 ) iir ( t ) = kpg ( t ) + kddg ( t ) dt + kcwithkp = amnvp , kdkp = 1l +1 m +1 n + ba , kc = d + cakp , where g is blood glucose level and d is the insulin infusion rate through the intravenous ( iv ) route . parameters a , b , and c can be calculated from the relationship between plasma insulin i and blood glucose levels in a normal person , which are written as ( 2 ) i ( t ) = ag ( t ) + bdg ( t ) dt + c . moreover , other parameters n and l are from next equations which are the pharmacokinetics of insulin infusion through the sc route : ( 3 ) dx ( t ) dt = iir ( t ) + lx ( t ) , dy ( t ) dt = lx ( t ) ( p + o ) y ( t ) , dz ( t ) dt = py ( t ) nz ( t ) , i ( t ) = z ( t ) v , where x , y , and z represent the insulin level in the two subcutaneous compartments and in the plasma , respectively . figure 2 shows such an x / y / z 3 - level model . at last , this is a simplified approach , forgoing adaptive control for ease of characterization and implementation . for most situations , it will perform as desired , but if it encounters a situation that it handles poorly , it will handle that situation poorly every time it occurs again in the future . experiments showed that the combination of the pole - assignment strategy and lispro insulin generated a similar trend to the use of the iv route with regular insulin . however , the combination of the pole - assignment strategy and regular insulin generated much worse result . a difficulty of the pole - assignment strategy is to repeatedly evaluate model parameters in each computation of the iir . to avoid re - evaluations of the model parameters , the self - tuning adaptive control closed - loop scheme employs a recursive assessment of the model parameters so that the glucose level of time period k , that is , gk , is evaluated from the glucose levels of time period k 1 through k h , that is , { gk1 , , gkh } , and the insulin doses of time period k 1 through k p , { idk1 , idkp } , as well as some unknown parameters , which can be written as ( 4 ) gk = m ( gk1 , , gkh , idk1 , idkp , ) , where p and h are time delays . since this method evaluates the blood glucose level of time period k from the previous evaluations and insulin doses , it can efficiently eliminate unnecessary re - evaluations of the model parameters . besides , according to glucose level gk , the next insulin dose is calculated as ( 5 ) j = ( gkgk1 ) 2ridk , such that i dk can minimize value j , where r is a weighting factor designed to control the amount of insulin dose . implementation of self - tuning adaptive control , shown in figure 3 , is quite similar to pole - assignment control , as it uses the same system modeling equations in order to compute the insulin infusion rate . the primary difference between the two methods is that another controller is used to constantly evaluate the system model , and may tune or redesign the pd controller parameters as needed to obtain more accurate results based upon minimum variance . one advantage of this control scheme is that it is comparatively easy for a physician to estimate the future trend of blood glucose levels from a set of the past inputs , where the model can be used to predict hypoglycemic or hyperglycemic events before they occur . a model predictive control ( mpc ) , or nonlinear predictive control ( nlpc ) algorithm attempts to learn what nominal means in a system , shown in figure 4 . in the case of blood glucose management , a nonlinear mpc algorithm uses sensor data to track glycoregulatory system parameters in order to predict the levels of required insulin infusions . it then uses models of the human glucose metabolism to estimate the effects of the insulin injection . an example of a model used is a nonlinear autoregressive ( narx ) model , where previous blood glucose ( bg ) levels and insulin dosage levels are run through a nonlinear function , often obtained through neural network learning . bayesian learning is applied using the model - predicted effect of the insulin , and its actual measured effect . the learning process adjusts system parameters in order to increase the accuracy of its predictions as more iterations are performed . using this method , the system will become increasingly accurate , and will begin to understand how the patient that it is calibrated to will react to insulin injections of varying compositions and strengths . apparently , the insulin - glucose system is complicated , and the system is considered to be nonlinear . in , in order to follow this nonlinearity , one method utilizes a collaboration of a neural network ( nn ) and nonlinear model predictive control ( npc ) technique , that is , neural predictive control . more precisely , nns and an npc are used to simulate the glucoregulatory system . a schematic diagram of the neural predictive control is shown in figure 5 . basically nns approach the problem of blood glucose management without attempting to explicitly describe the exact model of the blood glucose - insulin system . this is particularly useful in situations where patients have a disease that complicates normal model description , or an abnormality exists which makes prediction difficult using just measured parameters and sensor data . like other control strategies , the main goal of the neural predictive control is to achieve regulation of the glucose profiles for the type 1 diabetics predicting a future glucose curve from the nonlinear model with time delays , so it can follow a similar curve to the metabolism of normal people . a feed forward neural network employing backpropagation can be trained offline using accumulated patient data , including daily blood glucose readings as well as insulin dosages . a neural network will then be able to learn based upon experience , much as a human brain learns . this will help it to predict nonlinear behavior , even multiple orders removed , imperceptible to standard data interpretation methods . this capability to be intuitive helps to drive a system in which unknowns or immeasurable parameters are still accounted for , and abnormalities are detected and intelligently handled . in addition to the control variables , it also designs a cost function in relation to the insulin - glucose model . in the mechanism of the scheme , the neural predictive control makes consecutive control actions toward the glucose metabolism altering the control variables , so that the actions consequently minimize a designed cost function at each sampling time . however , the alteration of the control variables also changes the optimization problem at each sampling time . on the other hand , the model and its parameters can be of no difference during a whole examination . fortunately , in order to regulate the glucose profile , the so - called monomeric insulin ( mi ) analogs are currently available . these mi analogs have advantages that they are able to be absorbed through the subcutaneous route three or four times faster than human insulin resulting in that the rise of the plasma insulin concentration grows faster . besides , the mi analogs are more predicable than human insulin due to its less variability . in the forming of the control strategy , first develops a mathematical model of the insulin - glucose dynamics of the type 1 diabetics , which is mainly broken down into three parts : the subcutaneous insulin absorption model , glucose regulation model , and subcutaneous glucose model , shown in figure 6 . from the model , the subcutaneous insulin absorptionis calculated in two steps : the subcutaneous mi analogs infusion and utilization from the subcutaneous depot . with respect to the glucose regulation , in order to model the system mathematically , adopts a compartmental model in which there are single compartments for glucose and glucagon , and three compartments for insulin ( liver and portal insulin , plasma insulin , and insulin in the interstitial fluid ) . also in the model , net hepatic glucose balance , renal glucose excretion , and glucose utilization are simulated to generate numerical values . from the glucose regulation model , the subcutaneous glucose model is generated by investigating transfer rates between the plasma and subcutaneous compartments . consequently , the subcutaneous glucose model forms a linear , first - order system with the transfer function . in the second step , using numerical data from simulations of the mathematical patient model , the paper develops the nonlinear system by nns in order to make future blood glucose predictions . to do this , the paper utilizes a nonlinear autoregressive model ( narx ) because of its popularity and usefulness . , idknu ) + ek , where g is a sequence of subcutaneous glucose profiles , especially gk is a future glucose prediction , i d is a sequence of subcutaneous insulin infusion rates , ek is a noise , and ny and nu are both durations of glucose utilization and insulin activation , respectively . at this point , however , the approximation of the nonlinear function f is a hard task . a reason why to approximate the nonlinear function is difficult is that the function is required to be made up from finite data although there are usually infinite solutions for it . to resolve this difficulty , approximation based on regularization techniquesis used because it was proved that regularization principles consequently can derive networks with one layer of hidden units , that is , regularization networks . thus , the paper uses a function of radial basis function ( rbf ) networks , which are a subclass of regularization networks , in order to represent the nonlinear function f : ( 7 ) f ( x ( t ) ) = i = 1nwih ( xxi0 ) , h ( xxi0 ) = 1 ( ( xxi0 ) 2 + ) 2 , where h is a continuous function of rr , | | | | , represents the euclidean norm , xi are some proper center values selected from the data points , wi are some weight constants , and is a parameter representing the dispersion . also the regularized orthogonal least squares ( rolss ) algorithm is used to determine rbf weights and centers in order for f ( x ( t ) ) to fit the data under some constraints . the third step to modelthus , eventually controlling the glucose profiles is turned into resolving the minimization problem where a sequence of subcutaneous insulin infusions must sufficiently minimize the problem below ( 8 ) argminid j = [ j = n1np ( ejtej ) + j = 0nc1idt ( t + j ) uidt ( t + j ) ] , where i d = [ idk , idk1 , , idknc1 ] and nc , np , n1 , e , u are parameters of the controller for tuning . there are three steps for the process of a fuzzy logic algorithm : fuzzification , rules , and defuzzification.fuzzification : the input of a controller is an exact number , like the concentration of glucose is 100 mg / dl . what the fuzzification do is to fuzzy the concentration such as low concentration , high concentration , and proper concentration . every exact number has the weight of all these low concentration , high concentration , and proper concentration.rules : after defining the fuzzy concept of input , rules are made to decide what the output should be : more drug , a little drug , or no drug.defuzzification : after the rule , the output of fuzzy concept is obtained , for example , more of 0.8 and little of 0.2 . but the output which is the object model 's input must be an exact number , that needs to be defuzzification . by defuzzification , the output gets an exact number . fuzzification : the input of a controller is an exact number , like the concentration of glucose is 100 mg / dl . what the fuzzification do is to fuzzy the concentration such as low concentration , high concentration , and proper concentration . every exact number has the weight of all these low concentration , high concentration , and proper concentration . rules : after defining the fuzzy concept of input , rules are made to decide what the output should be : more drug , a little drug , or no drug . defuzzification : after the rule , the output of fuzzy concept is obtained , for example , more of 0.8 and little of 0.2 . but the output which is the object model 's input must be an exact number , that needs to be defuzzification . by defuzzification , the output gets an exact number . in the paper , it is assumed that there are two different inputs of the concentration of glucose and the change rate of concentration , and one output of the dose of drug . overlow , good , high , and overhigh are defined for the concentration . the dose of drug is defined as zero , little , ten rules are defined such that : if ( rate is overlow ) , then ( dosage is zero ) ; if ( concentration is overhigh ) and ( rate is low ) , then ( dosage is little ) ; if ( concentration is overhigh ) and ( rate is highest ) , then ( dosage is most ) ; and so forth . if ( rate is overlow ) , then ( dosage is zero ) ; if ( concentration is overhigh ) and ( rate is low ) , then ( dosage is little ) ; if ( concentration is overhigh ) and ( rate is highest ) , then ( dosage is most ) ; in a partially closed - loop scheme of the insulin - dependent diabetes therapy , measurements are conducted three to seven times per day , and insulin injections are also performed three to four times under the supervision of a physician . these decisions , for example , the number and type of insulin injections , insulin dosage , are made according to model - based or algorithmic - based decision support systems , such as dias , aida , and t - iddm . insulin injections are usually performed by using the subcutaneous ( sc ) route due to its management and safety . also there is an alternative route for insulin delivery that is ideal for control , the intravenous ( iv ) route . figure 7 shows a control flow of a partial closed - loop scheme . while in the closed - loop systems , the blood glucose levels are automatically monitored by an implantable sensor and according to the measurements , insulin infusions are carried out in the use of an insulin pump or three or four times of the insulin injections , in the partial closed - loop , the metabolic controls partly rely on the physician 's evaluations of the measurements of the blood glucose levels , the amount of insulin injections and physical exercises as well as glycosuria and ketonuria . moreover , as other metrics of the evaluation , medium period indicators , such as glycated hemoglobin ( hba1c ) , are captured , where the blood glucose levels of the past 60 days can be seen . in other words , the partial closed - loop scheme is made out of a collaboration of the feedforward and feedback controls , and usually feedforward controls are made by clinicians who determine it from the patient 's lifestyles . however , these evaluations largely rely on doctor 's experiences . from the objective of the insulin therapy that aims to reconstruct the artificial insulin metabolisms in relation to the levels of blood glucose in the body , it is typically an optimization problem that is viewed from four dimensions : the number of injections , time of injection , insulin type , and insulin dosage . basically , this four - dimensional space optimization is intrinsic . besides , occasionally a clinician provides him / her with a feedforward strategy from the patient 's lifestyle . the insulin regiment prescribed by a doctor , to be administered manually , constitutes partially closed - loop control . a physician will dictate an insulin administration routine to a patient , variant upon a patient 's lifestyle . patients under such a system monitor their blood glucose level several times a day , administering insulin based upon prescribed tables according to their schedule and bg level . that has traditionally been used by insulin - dependent diabetics , but it performs poorly compared to other methods . partially , closed - loop control is far from real time and only updates its control routine at scheduled physician visits . furthermore , lifestyle events such as eating , sleeping , or working out must be accounted for by the patient in their interpretation of insulin tables , introducing the very real danger of human error . the bergman model is one of the virtual diabetes patient models represented in the literature . in the bergman model , the certain dynamics of the diabetes patient system can be represented as mathematical equations by employing three - order model : a glucose compartment , g , a remote insulin compartment , x , and an insulin compartment , i . basically , the bergman model has a very simple form and is represented as follows : ( 9 ) dg ( t ) dt = ( p1 + x ( t ) ) g ( t ) + p1gb , dx ( t ) dt = p2x ( t ) + p3 ( i ( t ) ib ) , di ( t ) dt = ( g ( t ) h ) tni ( t ) , where g ( t ) represents plasma glucose and i ( t ) represents plasma insulin at certain time t , which are initialized at t = 0 . x ( t ) represents the effect of insulin causing net glucose disappearance , for example , the remote insulin concentration . gb represents a base value of plasma glucose and likewise , ib represents a base value of plasma insulin . moreover , p1 is a parameter representing glucose effectiveness , p2 fractionally represents the insulin - dependent increase rates and p3 fractionally represents the net remote insulin disappearance rates . h is a threshold where the plasma glucose levels are expected not to exceed . when the plasma glucose levels exceed the threshold , the second - phase of insulin secretion will be performed with additional insulin secretion . furthermore , insulin is removed from the plasma insulin space at rate of n. the bergman model is used for efficiently predicting the certain diabetes patient system dynamics . the automated insulin dosage advisor ( aida ) is a virtual diabetes patient model that was originally designed for the educational purpose so as to help patients and clinicians learn effective glycemic control . basically , aida is used for estimating effects of insulin injections and regimens in type 1 diabetic therapy . more precisely , aida is a simulation program that models the insulin - glucose dynamics based on the physiological rules around metabolism of a single glucose compartment . to model the insulin - glucose dynamics , metabolism around the glucose compartment is carried out such that delivering glucose into the compartment is conducted both by being absorbed by the intestine and by being produced by the liver ( gluconeogenesis ) . on the other hand , removing glucose out of the compartment is carried out by insulin - independent and insulin - dependent glucose utilization . more precisely , by the insulin - independent glucose utilization , glucose is carried from the compartment into red blood cells , the central nervous system and viscera , whereas by the insulin - dependent glucose utilization , glucose is carried from the compartment into the liver and periphery . to hepatic and peripheral glucose utilization , aida is designed to have a capability of adding different insulin sensitivities by modeling them separately . besides , the renal threshold is defined in order to model renal glucose losses . figure 9 shows a variation of the net hepatic glucose balance in terms of the changes of the amount of the active insulin and blood glucose ( bg ) levels in the form of nomograms . moreover , the aida model applies a process of insulin absorption derived by berger and rodbard to its pharmacokinetics of the model . in addition , insulin is separated into two compartments where one is for plasma insulin and the other is active insulin . on the basis of a physiological model , active insulin controls metabolism . on the other hand , hepatic degradation produces insulin from plasma insulin . in the use of aida , by comparing home - monitored blood glucose levels to a typical behavior of blood glucose of a patient , for example , the model day , metabolic problems are identified . according to particular metabolic problems , aida can generate several possible solutions , and among these possible solutions , one best solution will be selected according to a nonlinear dynamic model of the insulin - glucose system . at last , this nonlinear dynamic model of aida consists of four differentials , 11 algebraic equations and 17 parameters . from the data , the model will be constructed while simulations are performed for each therapeutic choice to optimize the following cost function : ( 10 ) j ( g ) = 0t ( g ( t ) g0 ) 2dt , where g0 describes a set point . the diabetes advisory system ( dias ) is a nonlinear model of the blood glucose - insulin system based upon real - life parameters , versus simply bg measurements . it incorporates qualitative and quantitative input from the user , including bg levels , meals , and past insulin injections . the system uses a discrete - time finite - state model of the system based upon user input . the system uses what it understands about the system as a whole , including dormant compartmentalized insulin , predigested carbohydrates , and current bg levels to compute a bayesian estimate of future bg levels . it uses all known information in order to compute the value of the optimal dosage such that it minimizes an associated cost function ( i.e. , hypoglycemia is far more costly than hyperglycemia , due to its possibility of severe damage ) . over iterations , it will adjust its system model parameters to better account for patient specific reactions it detects . for example , in dias , the flow of the physiological calculation of carbohydrate is drawn by figure 10 . besides , dias has three different modes , for example , the learning mode , the prediction mode , and the advisory mode . in figure 10 , there are two associated state variables , for example , cho and bg , and both of them record how much carbohydrate content exists in the gut compartment and the blood compartment , respectively . for example , in this model , carbohydrate content is , at first , taken in from meals and delivered to the gut and the blood compartment . during the delivery to the blood , some of carbohydrate content is absorbed by the gut and only the rest of it is delivered to the blood and transformed into the main energy . in addition , this flow of carbohydrate is redrawn more precisely by using difference equations , which are shown in figure 11 . in this redrawn model , the amount of carbohydrate content in both the gut ( cho ) and blood ( bg ) compartment is updated in every hour such that both increase and decrease of carbohydrate content are kept track of in each compartment . in figure 11 , the gut - abs process variable represents how much glucose is absorbed by the gut , and the rest of glucose remains in the gut and is recorded in the cho state variable . besides , the renal - cl process variable represents how much glucose is removed , the ins - indep - util process variable represents how much glucose is used independently of insulin , the ins - dep - util , on the other hand , represents the amount of glucose to be used for insulin - glucose dynamics , and the glu - prod process variable represents the amount of glucose produced by the liver . in dias , there are also two input variables , for example , meal and ins - inj , where the meal input variable is carbohydrate intakes at given time from each meal , and the ins - inj input variable represents the amount of the external insulin injection . furthermore , to adjust individual physiological differences , two other parameters are employed , for example , ins - sens and nph - max , where the ins - sens parameter stands for the insulin sensitivity that affects the active insulin ( act - ins ) variable , and the nph - max parameter represents the time when nph insulin achieves the maximum absorption or concentration , shown in figure 11 . the + and symbols in figure 11 represent fluctuation of carbohydrate on the cho and bg state variables . for example , the cho state variable at hour 1 can be written as an equation such that cho ( hour 1 ) = cho ( hour 0 ) gut - abs ( hour 0 ) + meal ( hour 1 ) . the transition among the states in a graph of difference equations in dias is defined by causal probabilities . more precisely , the graph representation of difference equations of dias is defined by a causal probabilistic network ( cpn ) or a bayesian network using the hugin approach . for example , the transition probability of the amount of carbohydrate absorbed by the gut given the carbohydrate content in the gastrointestinal tract is p ( gut - abs cho ) . as previously mentioned , there are three modes in dias to conduct a calculation of the optimal insulin dosage ( the decision support system ) : the learning mode , the prediction mode , and the advisory mode . at first , the learning mode is used to generate the two adjustable parameters , for example , the insulin sensitivity ( ins - sens ) and time - to - peak absorption of nph ( nph ) , from the collection of standard data , such as the amount of blood glucose , insulin injection , and carbohydrate content in the meals . for instance , an example of a prediction of blood glucose transition from , from the measurements of blood glucose , the mixture of short - acting insulin and intermediate - acting insulin and the carbohydrate intake , the transition of blood glucose is predicted as a straight line . secondly , the objective of the prediction mode is to predict the resulting blood glucose concentration from given an intake of carbohydrate and insulin injection as well as two adjustable parameters estimated in the learning mode . there is a risk of hypoglycemia around lunch time , the ratio of the insulin mixture is manually changed in the morning to handle the condition . as an example of the objective of the prediction mode of dias given from , there is a risk of hypoglycemia around lunch time , the ratio of the insulin mixture is manually changed in the morning to handle the condition . in dias , the advisory mode , which is considered as a special version of the prediction mode , is used to generate possible insulin therapies that avoid the overall risk of an excess or shortage of blood glucose by minimizing an utility measure . in the advisory mode , the manual changes of the insulin regimen conducted in the prediction mode , such as switching to a different mixture of insulin , are automatically replaced to an optimal way by the system . for example , a replaced version of an optimal insulin injection procedure is used by the advisory mode , where the mode recommends reducing the amount of nph insulin from 10 to 6 u before dinner resulting in avoiding hypoglycemia during bedtime . as an example of a result calculated by the dias advisory mode , dias further generates an optimal solution of an insulin therapy automatically to avoid the overall risk of an excess or shortage of blood glucose by minimizing a utility measure . the eu developed telematic management of insulin dependent diabates mellitus ( t - iddm ) which was a telemedicine system that supported clinician 's decision - making for providing insulin for the insulin - dependent diabetics . basically the system consist of two modules , for example , a patient unit ( pu ) and a medical unit ( mu ) , and two decision support elements , for example , a rule - based reasoner ( rbr ) and a case - based retrieval system ( cbrs ) . the system architecture is shown in figure 12 . with the system , the pu is basically responsible for monitoring changes of the blood glucose concentration in patients , and the physiological data are transferred to the hospital database via the internet . in addition to the hospital database , the pu also has a local database that enables patients to deal with their own diabetics cases autonomously . on the other hand , thus the mu can visualize incoming data from patients , analyze them , and generate optimal insulin treatments for particular patients . basically , the mu is a web - based application made up of collaborating five servers : a database server , temporal abstraction server , data analysis server , decision support system , and web server . data communication is made up between the two devices . from the perspective of the decision support for the therapy , the rbr and cbrsare designed to resolve the following premises . at first , the insulin - glucose dynamics is very complicated that only highly parameterized nonlinear models can be applied to it although it is usual to have no more than three or four blood glucose tests per day in the insulin - dependent diabetes therapy , which is not enough to model the dynamics . due to the limitation of the measurements , some parameters are required to be fixed in all cases whereas only a few parameters are free to be set up according to each patient case . however , this limitation of setting parameters must make the models and the quality of prediction inflexible and inaccurate . one goal of t - iddm is to refine the models to generate more precise prediction of the insulin - glucose models from the limited inputs . t - iddm provides the professionals with more systematical way to plan the therapy for particular insulin - dependent diabetics . at last , the same metabolic behavior occasionally generates different results . for example , either honeymoon effect or other troubles may cause the same number of hypoglycemia over a month . however , this type of wrong diagnosis may fall the diabetic into a critical situation . therefore , in independence of metabolic behaviors , t - iddm should employ context that can generate different results from the same metabolic behavior . also the introduction of context may reduce the search space from whole possible solutions . in the implementation of the rbr , to optimize the therapy , it runs four sequential tasks each of which is connected to a set of rules through a forward chaining mechanism . these four sequential tasks are the data analysis , problem identification , suggestion selection , and therapy revision . however , only the rbr is sometimes not enough to produce reliable suggestions of the therapy for poorly controlled patients . therefore , in consideration of that situation , in addition to the rbr , t - iddm employs the cbrs to improve the system to be more accurate . the objective of the cbrs is to search a pool of past cases for similar situations to the current condition and utilize them to help the user make an optimal decision for the current condition . a set of past cases is narrowed for searching according to very high - level view of the cases by a nave bayes strategy , and after that , in the proper retrieval step , cases having the closest to the current situation are effectively chosen and shown to the user . regarding the artificial insulin - glucose control system , designs a fuzzy logic reasoning system . there are mainly two modules ( e.g. , an analog signal conditioning board and a microcontroller board ) and other interface devices , such as a lcd display , a sixteen button keypad , and alarm system , along with the operating software to work the system . the software operates the system according to a fuzzy logic reasoning method . in the system , an analog signal conditioning board is responsible for generating electrical signals from vital parameters monitored by several biomedical sensors . these parameters include sweating , snoring , heart rate , and eeg . in the meantimethe system works with batteries so that it can be portable . in the use of the system , several electrodes are placed on the particular segment of the human body capturing the four physiological parameters . basically , these electrodes are connected to an analog signal conditioning board that amplifies and filters the vital signs . since a 10 bit a / d converter interfaces a microcontroller board , the analog signals can be converted to the digital signals with the sampling rate of 100 samples / s . the microcontroller invokes the fuzzy logic reasoning algorithm that resides on the rom of the system to process the four parameters . this survey mainly focuses discussions on control methods for the insulin - dependent diabetes ( type 1 diabetes ) . three control methods are introduced in this paper , namely , open - loop , fully , and partially closed - loop control methods . in either of them , the objective of the control methods is to suppress the blood glucose profiles to avoid a condition of hyperglycemia . because diabetes is a metabolic disorder which is characterized as complete or partial lack of insulin functionality , therapies can be done by making up for the lack of insulin supply by exogenous insulin replacement . in the open - loop control method , the insulin replacement is programmed such that the amount of the insulin supply follows the non - diabetic insulin delivery . the open - loop control method usually does not count on utilization of blood glucose sensors , but instead , a transition of the insulin supply is captured by carefully examining the nondiabetic in advance . on the other hand , fully and partially closed - loop controls typically rely on feedbacks from the blood glucose sensor measurement . in the closed - loop control method , the system loop is fully closed so that it does not require any assessment by physicians . it is only based on feedbacks from one or more blood glucose sensors , and it usually requires continuous glucose measurements . thus from the measurements of blood glucose profiles , a rate of the insulin supply by an insulin pump is adjusted so that it can lead to neither conditions of hyperglycemia nor hypoglycemia . examples of the closed - loop control method are pole - assignment model , self - tuning adaptive control , model predictive control , and nonlinear predictive control . in addition to the blood glucose sensor feedbacks , partially closed - loop control also relies on feedforwards by physicians . in the partially closed - loop control method , the blood glucose measurements are conducted three to seven times per day and insulin injections are done three or four times per day . although both the blood glucose samples and insulin injections are discrete , these are compensated by physicians feedford assessment of insulin requirements . usually a calculation of the insulin supply utilizes a flow chart or table which describes complex relations between blood glucose reduction and insulin supply . examples of the partially closed - loop control method includes bergman model , automated insulin dosage advisor ( aida ) and diabetes advisory system ( dias ) . hence challenges of the blood glucose control methods are to delay the emergence of diabetic complications but not cure the patients from diabetes . in practice , three control methods introduced in this survey partially satisfy these requirements . however , our expectation is that the progress of the technology will enable the construction an artificial pancreas that follow the regular functionality of the actual pancreas , and this new technology must lie on the current control technologies .\noutput:\n" }, { "from": "agent", "value": "we survey blood glucose control schemes for insulin - dependent diabetes therapies and systems . these schemes largely rely on mathematical models of the insulin - glucose relations , and these models are typically derived in an empirical or fundamental way . in an empirical way , the experimental insulin inputs and resulting blood - glucose outputs are used to generate a mathematical model , which includes a couple of equations approximating a very complex system . on the other hand , the insulin - glucose relation is also explained from the well - known facts of other biological mechanisms . since these mechanisms are more or less related with each other , a mathematical model of the insulin - glucose system can be derived from these surrounding relations . this kind of method of the mathematical model derivation is called a fundamental method . along with several mathematical models , researchers develop autonomous systems whether they involve medical devices or not to compensate metabolic disorders and these autonomous systems employ their own control methods . basically , in insulin - dependent diabetes therapies , control methods are classified into three categories : open - loop , closed - loop , and partially closed - loop controls . the main difference among these methods is how much the systems are open to the outside people ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: to produce a conceptual summary of literature focusing on models which inform and guide the transition from paediatric to adult services for adolescents and young adults ( aya ) . the review was conducted as part of a larger study exploring the experiences of aya in their transition from the paediatric to the adult cancer setting . this review draws on interpersonal , relational and social constructionist perspectives of adolescence and erikson 's stages of psycho - social development . a critical narrative review , informed by systematic techniques for searching and appraisal , was conducted on recently published ( 19982008 ) literature which focused on transition models from across a range of illness conditions . current models do not adequately meet the needs of adolescents during transition as they are limited by the level of understanding of adolescent development which they incorporate . therefore , models are needed which reflect the dynamic and often complex nature of adolescence and contextualise the interrelationship of transitioning between services and life - course transitions for aya with chronic conditions . to ensure effective co - ordination and continuity of care during the transition process , pathways of care should be informed by and constructed within both medical and psycho - social paradigms .\noutput:\n" }, { "from": "agent", "value": "purposeto produce a conceptual summary of literature focusing on models which inform and guide the transition from paediatric to adult services for adolescents and young adults ( aya ) . the review was conducted as part of a larger study exploring the experiences of aya in their transition from the paediatric to the adult cancer setting.theorythis review draws on interpersonal , relational and social constructionist perspectives of adolescence and erikson 's stages of psycho - social development.methodsa critical narrative review , informed by systematic techniques for searching and appraisal , was conducted on recently published ( 19982008 ) literature which focused on transition models from across a range of illness conditions.results and conclusionscurrent models do not adequately meet the needs of adolescents during transition as they are limited by the level of understanding of adolescent development which they incorporate . therefore , models are needed which reflect the dynamic and often complex nature of adolescence and contextualise the interrelationship of transitioning between services and life - course transitions for aya with chronic conditions.discussionto ensure effective co - ordination and continuity of care during the transition process , pathways of care should be informed by and constructed within both medical and psycho - social paradigms ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: each year in the us 8000 neonatal cases of sepsis due to gbs are reported . up to 30 % of women carry gbs in the urogenital tract , intestinal tract , or both . penicillin is the drug of choice for prophylaxis and treatment of gbs infection . in patients allergic to penicillin , erythromycin and clindamycinthe proportions of gbs isolates with in vitro resistance to erythromycin and clindamycin have steadily increased since 1996 . the prevalence of resistance among invasive gbs isolates in the united states and canada ranged from 7 % to 25 % for erythromycin and from 3 % to 15 % for clindamycin in reports published between 1998 and 2001 . the genetic basis for macrolide and lincosamide resistance in gbs has been studied extensively . the ermtr varianta ( ermtr ) and ermb genes modify a site in 23s rrna common to the binding of macrolides , lincosamides , and streptogramin b antibiotics . the macrolide efflux ( mefa ) gene allows the bacterium to actively expel the antibiotic from the interior of the cell . both the ermtr and ermb geneshave been associated with the mlsb constitutive phenotype in gbs ( erythromycin - resistant , clindamycinresistant ) ; the ermtr gene with the mlsb inducible phenotype ( erythromycin - resistant , clindamycin - susceptible , d - test positive ) ; and the mefa gene with the m phenotype ( erythromycin - resistant , clindamycin - susceptible , d - test negative ) . current recommendations state that all pregnant women should be screened at 3537 - week gestation for vaginal and rectal gbs colonization , and that susceptibility testing should be performed on isolates from women with penicillin allergy . the cdc further recommends d - testing for gbs isolates that are erythromycin - resistant and clindamycinsusceptible on initial disk diffusion testing . vancomycin is now the recommended antimicrobial prophylaxis for perinatal gbs disease prevention in the penicillin allergic patient whose isolate is known to be resistant to erythromycin and clindamycin ( constitutively or inducibly ) , or whose isolate has not been tested for resistance . this policy is at odds with hospital infection control practices advisory committee ( hicpac ) guidelines urging limitation of vancomycin use . while a newly licensed pcr - based diagnostic test allows for intrapartum detection of gbs colonization in women who have had no prenatal care or for whom culture results are otherwise unknown , vancomycin would still be indicated in the penicillin allergic patient with a positive test result due to a lack of susceptibility information . the disk diffusion method , which takes 1824 hours to be performed , is currently the most commonly used method for determining gbs susceptibilities . an assay for the rapid detection of the erm and mefa genes might allow for more judicious use of vancomycin . the aim of the present study was to develop rapid assays using real - time pcr for detection of these genes and to assess their performance using the disk diffusion method as the standard . a secondary goal was to assess the susceptibility of isolates demonstrating constitutive clindamycin resistance to a new ketolide antibiotic , telithromycin . three hundred and forty consecutive , unique patient gbs isolates from screening cultures collected at our facility in 2004 were studied . disk diffusion testing of the isolates was accomplished according to national committee for clinical laboratory standards ( nccls ) guidelines . briefly , gbs growth from an overnight ( 18 - hour ) sheep blood agar plate was suspended in 0.9 % saline to a density equivalent to the turbidity of the 0.5 mcfarland standards . this suspension was inoculated on mueller - hinton agar supplemented with 5 % defibrinated sheep blood . erythromycin ( 15 g , remel , lenexa , kan , usa ) and clindamycin ( 2 g , remel ) disks were placed on the plates . the plates were incubated at 35c in an atmosphere of 5 % co2 for 20 to 24 hours beforemeasuring zones of inhibition . d - testing was performed for erythromycin - resistant / clindamycin - susceptible isolates , as described previously . clindamycin disks and erythromycin disks were placed approximately 15 mm apart on mueller - hinton agar supplemented with 5 % defibrinated sheep blood that had been inoculated with a standardized ( 0.5 mcfarland ) suspension of gbs . the plates were incubated at 35c in an atmosphere of 5 % co2 for 20 to 24 hours before observing for d - shaped blunting of the circular zone of inhibition around the clindamycin disks on the side facing the erythromycin disk . further susceptibility testing was performed for 50 isolates exhibiting an mlsb constitutive phenotype using telithromycin ( 15 g , sanofi - aventis , bridgewater , nj , usa ) disks . genomic dna from gbs isolates was extracted using the magna pure lc automated extraction system ( roche applied science , indianapolis , ind , usa ) per manufacturer 's recommendation . real - time fluorescent pcr was used to detect cfb , a gbs - specific gene target , and the mls resistance genes ( ermtr , ermb and mefa ) . the primers and hybridization fluorescent resonance energy transfer ( fret ) probes were designed using the lightcycler probe design software version 1.0 ( roche applied science , indianapolis , ind , usa ) . the primers for the 247 bp fragment of cfb gene ( genbank accession no . nc_004116 ) are as follows : forward primer ( 3348 ) 5 to 3 , aactctagtggctggt ; and reverse primer ( 279264 ) antisense 5 to 3 , ggcacgcaatgaagtc . the internal fret hybridization probes for cfb gene fragment have the following sequence : upstream probe ( 93112 ) 5 to 3 , agtgacaactccacaagtgg - fitc ; downstream probe ( 115144 ) 5 to 3 , 640red - aatcatgtaaacagtaataatcaagcccag - phosphate . the primers for the 162 bp fragment of ermb ( genbank accession no . x72021 ) are as follows : forward primer ( 390406 ) 5 to 3 , ctacaagcgtaccttgg ; and reverse primer ( 551533 ) antisense 5 to 3 , tctggaacatctgtggtat . the internal fret hybridization probes for 162 bp ermb gene fragment have the following sequence : upstream probe ( 468483 ) 5 to 3 , gctgccagcggaatgc - fitc ; downstream probe ( 4865143 ) 5 to 3 , 640red - tcatcctaaaccaaaagtaaacagtgtct - phosphate . the primers for the 281 bp fragment of ermtr gene ( genbank accession no . af443782 ) are as follows : forward primer ( 505524 ) 5 to 3 , ccttattgtagagaggggat ; and reverse primer ( 785768 ) antisense 5 to 3 , gcttcagcacctgtctta . the internal fret hybridization probes for ermtr gene detection are the following : upstream probe ( 607627 ) 5 to 3 , gccacgagcatattttcaccc - fitc ; downstream probe ( 630660 ) 5 to 3 : 640red - agcctaatgtagattctgtattgattgtact - phosphate - . the primers for the 179 bp fragment of mefa gene ( genbank accession no . ay071836 ) are as follows : forward primer ( 294309 ) 5 to 3 , ggagctacctgtctgg ; and reverse primer ( 472457 ) antisense 5 to 3 , caactgccggactaac . the internal fret hybridization probes for mefa gene detection are the following : upstream probe ( 341364 ) 5 to 3 , ttggaacagcttttcataccccagfitc ; downstream probe ( 367388 ) 5 to 3 , 640red - ctcaatgcggttacaccacttt - phosphate . the realtime fluorescent pcr cycling was carried out in the lightcycler ( roche applied science , indianapolis , ind , usa ) in 20 l reaction mixture containing 5 l ( 1 ng ) template , 5 mm mgcl2 , 0.2 mm dntp , 1 u taq polymerase , 500 nm forward and reverse primers , and 100 nm upstream and downstream hybridization probes . cycling conditions include an initial denaturation step at 94c for 60 seconds , followed by 35 cycles which consist of annealing at 60c for 30 seconds , extension at 72c for 5 seconds , and denaturation at 94c for 1 second . progress of real - time fluorescent pcr was monitored in channel 2 on the lightcycler . during the optimization phase of the real - time pcr assays , the production of a single pcr product was confirmed in 3 % agarose gel electrophoresis visualized by sybr green ( molecular probes , eugene , ore , usa ) staining at 1:10000 dilution . stata version 9.0 ( college station , tex , usa ) was used to calculate sensitivity , specificity , positive predictive value , and negative predictive value , and their corresponding 95 % confidence intervals . the pcr assays were optimized in the lightcycler instrument . figures 1 and 2 demonstrate representative fluorescence curves and agarose gel electrophoresis results for the ermb assay . each component assay was run in separate tubes with the same pcr reaction and cycling conditions . a total of 340 unique clinical gbs isolates collected from vaginal - rectal swabs were analyzed in this study . all isolates were positive for gbs - specific cfb gene by real - time pcr . one hundred isolates ( 29 % ) demonstrated resistance to erythromycin and / or clindamycin via disk diffusion testing ( table 1 ) . among the 100 resistant isolates , 79 demonstrated an mlsb constitutive phenotype , 8 an mlsb inducible phenotype , and 11 an m phenotype , while 2 were susceptible to erythromycin , but were resistant to clindamycin . no resistance to telithromycinwas detected among the 50 randomly selected mlsb constitutive strains that were tested . among the 340 isolates , a single resistance gene was detected in 105 isolates ( 31 % ) , while 21 isolates ( 6 % ) harbored two genes . the genotype and phenotype were discordant in 14 % of isolates ( table 2 ) . among the 240 fully susceptible isolates , at least one resistance gene was detected in 93 of the 100 resistant isolates . presence of the mefa gene predicted the m phenotype with a sensitivity of 55 % ( 95 % ci 23 % 83 % ) , specificity of 94 % ( 95 % ci 90 % 96 % ) , ppv of 22 % ( 95 % ci 9 % 42 % ) , and npv of 98 % ( 95 % ci 96 % 99 % ) . presence of at least one erm gene within an isolate predicted constitutive or inducible resistance to clindamycin with a sensitivity of 93 % ( 95 % ci 86 % 97 % ) , specificity of 90 % ( 95 % ci 85 % 93 % ) , positive predictive value of 76 % ( 95 % ci 67 % 84 % ) , and negative predictive value of 97 % ( 95 % ci 94 % 99 % ) . because we had no a priori estimates for negative predictive value , post hoc power analyses were conducted using the obtained npv of 97 % to assess whether the sample size collected was sufficient to exclude negative predictive values as low as 90 % for erm gene predicting clindamycin resistance . in order to be 95 % certain ( power = 0.95 ) that a negative predictive value as low as 90 % was excluded ( alpha level , two - tailed = 0.05 ) , at least 133 test negative patients would be necessary . our number of test negative patients exceeded this value , making the power more than adequate for our research question . we developed a real - time pcr method that can be used to rapidly detect macrolide resistance genes ( ermb , ermtr , and mefa ) from a pure gbs isolate . previous studies have focused on identifying genes present in resistant isolates of gbs . to make these molecular techniques useful to clinicians , one must ask the question in reverse : does the presence of one of these genes predict in vitro resistance and possible treatment failures ? a previous study examined this relationship in 1043 strains of macrolide - resistant streptococcus pyogenes and streptococcus pneumoniae and found a 10.2 % rate of error when predicting the genotype from phenotypic data . while we observed a slightly higher level of discordance between genotype and phenotype in gbs ( 14 % ) , our data suggest that the absence of detection of an erm gene predicts in vitro susceptibility to clindamycin with an npv sufficient to make the assay clinically useful . while this would cut the 1824 hours that it takes to perform disk diffusion testing down to 1 - 2 hours , the ideal molecular test would be performed directly from a clinical specimen . because many other bacteria that colonize the urogenital and intestinal tracts harbor erm genes , direct analysis of clinical specimens with these assays would likely not yield useful results . moreover , erm genes are located in a conjugative s. agalactiae plasmid , pip501 , which is highly homologous to numerous plasmids found in other bacterial species . thus , detection of clindamycin resistance in gbs directly from a clinical specimen , as does a commercially available pcr - based test for detecting mrsa , may not be possible without prior isolation . . it would be ideal if an alternate agent with 100 % efficacy and with no propensity for inducing resistance was available . telithromycin , the first ketolide to receive fda approval in the us , may be such an agent . our findings mirror those of other researchers : telithromycin is broadly active against gbs , including those strains exhibiting resistance to erythromycin and clindamycin . a recent report describing 51 telithromycin - susceptible strains of mlsb constitutive gbs that showed inducible resistance to telithromycin in the presence of erythromycin does , however , raise the possibility that resistance might develop while a patient is on therapy and result in a treatment failure . still , given its excellent in vitro activity against this organism , the short course of therapy used for this indication , and the lack of convincing evidence regarding the clinical importance of this type of inducible resistance , clinical testing of telithromycin as intrapartum chemoprophylaxis against neonatal gbs infection seem warranted . while altered expression or regulation of the ermtr gene present in one of these isolates might explain its phenotype , the other strain did not contain an erm or mefa gene . this phenotype , the genetic basis for which remains unknown , is rare in north america , but is already widespread in new zealand . the existence of such strains presents a pitfall in inferring clindamycin susceptibility from erythromycin susceptibility when only the latter is tested . this underscores the importance of performing in vitro testing for resistance to clindamycin on isolates obtained from persons with penicillin allergy . finally , we observed 5 isolates that were resistant to both erythromycin and clindamycin , and yet contained none of the common resistance genes for which we tested , which is consistent with previous reports .\noutput:\n" }, { "from": "agent", "value": "objective . our objective was to assess the ability of real - time pcr to predict in vitro resistance in isolates of group b streptococcus ( gbs ) . methods . the first real - time pcr assays for the genes known to confer resistance to erythromycin and clindamycin in gbs were developed . three hundred and forty clinical gbs isolates were assessed with these assays and compared with conventional disk diffusion . results . the presence of an erythromycin ribosome methylation gene ( ermb or ermtr variant a ) predicted in vitro constitutive or inducible resistance to clindamycin with a sensitivity of 93 % ( 95 % ci 86 % 97 % ) , specificity of 90 % ( 95 % ci 85 % 93 % ) , positive predictive value of 76 % ( 95 % ci 67 % 84 % ) , and negative predictive value of 97 % ( 95 % ci 94 % 99 % ) . conclusion . this rapid and simple assay can predict in vitro susceptibility to clindamycin within two hours of isolation as opposed to 1824 hours via disk diffusion . the assay might also be used to screen large numbers of batched isolates to establish the prevalence of resistance in a given area ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: we know that the onset of drug addictions is determined by a complex combination of constitutional ( biological ) , social , and psychological factors . physiological components play a crucial role in the maintenance of psychological anxiety , associated with physical abstinence , but they are not the one and only etiological factor behind this disorder and they can not entirely explain the motivation for subsequent relapses . it is clear that every psychoactive drug induces a specific state of intoxication , but individual psychopathology largely defines the subject 's reaction towards the pharmacological effects . bearing in mind these assumptions , we review a series of developments in the understanding of substance abuse starting with classical psychodynamic approaches based on drive / conflict models . then , we present comprehensive theories of affect regulation which we see as a starting point for the transition to modern mentalization - based conceptualizations . we describe the shift from the initial emphasis on instinctual gratification to the investigation of ego development and pathology . we show how contemporary psychodynamic clinicians and researchers can increasingly rely on mentalization based theories to explain personality pathology . there is clear evidence supporting neurobiological and neurocognitive adaptations to specific drug exposure , the natural history of addiction involving spontaneous recovery with minimal intervention , consideration of now copious evidence from other therapeutic interventions such as motivational interviewing that appear to also emphasize the interpersonal environment in treatment . our main aim is to examine the evolution of psychodynamic approaches to addictions which we see as parallel to the general development in psychodynamic clinical theories . abraham tried to conceptualize this form of pathology from the point of view of the libidinal theory , that is , as a symptom of regress to oral fixations and striving for orgasmic experiences . rad was the first to point out that not the toxic agent itself , but the impulse to use it , defines addictions . in general these authors understood substance abuse from the point of view of euphoric - pleasurable experiences and believed that the symptom has aglover , however , made an important breakthrough with his hypothesis that the psychoactive substance could be usedprogressively not only for regressive satisfaction , but also for protecting the subject from primitive ( destructive and self - destructive ) impulses or even psychosis . these ideas would later serve as a basis for khantzian 's work on the self - medication hypothesis . the main difference between ego - psychological theories and classical - drive / conflict models is that ego psychologists shift the focus from the symptom to the personality deficits of addicts and their incapability for coping with traumatizing anxiety . drug use is related to specific ego pathology manifested in quick shifts from depressive states to intensive arousal in conflictual relations with important others . addicts react to situations of crisis with affect regression ( totalization of feelings ) , which is dealt with by splitting unacceptable parts of internal or external reality and denying their existence . however , only when these series of operations are pharmacologically reinforced , a sense of mastery and raised self - esteem can be restored . this generation of psychodynamically oriented clinicians concentrates on the clinical reality that patients with drug addiction complain of being either overwhelmed by intolerably painful affects or cut off from their emotions . referring to these characteristics of the affective life of addicts , wieder and kaplanthe problem with drug addicts is that the primitive defense mechanisms they employ do not efficiently protect them from excessive anxious and depressive states . consequently , addicts present not only interpersonal difficulties , affect storms , and impulsive behavior , typical for patients with borderline personality disorder , but their whole emotional life is in a way much more easilythus , impaired affect regulation comes into focus as a central diagnostic feature of this disorder . this term denotes a qualitative transformation of affective states with modification of their intensity and / or duration . it encompasses an interaction between neuro - physiological , motor - expressive , and cognitive - experiential areas . constant defensive blocking of affectivity leads to a state in which emotions are treated as physiological attacks setting vicious circles such as i am afraid to be afraid . we can safely generalize that the contemporary psychodynamic approach to drug addictions abandoned altogether early conceptualization of pleasure seeking and symbolic importance of the drug . instead , leading authors like khantzian see the motivation behind substance use as an attempt for self - medication . he observes that patients addicted to opiates rely on the antiaggressive effects of the substance which block disorganizing and threatening affective states of anger , pain , shame , and loneliness . khantzian convincingly shows that regressive aspects of the psychopharmacological effect have been excessively stressed , leading to a neglect of its progressive functions , that is , blockage of primitive psychic states and reinforcement of ego defenses drug addicts do not just search for ankrystal points that only when the small child is protected from exposure to continuous trauma in early relations , it can develop affect tolerance during latency and adolescence . he makes it clear that primary self - regulation deficits in drug addicts encompass a tendency for affective regress , deficient capability for using anxiety as a signal , and impaired tolerance for painful emotions , especially the primitive affect of undifferentiated anxiety and depression . these deficiencies showing failure in the desomatization , verbalization , and symbolization of affective experiences are quite often observable in psychosomatic conditions characterized by the state of alexithymia . addicted patients often share some of the following basic components of alexithymic functioning : ( 1 ) difficulty in identification and differentiation of feelings and bodily senses in a state of emotional arousal , ( 2 ) difficulty in describing feelings , ( 3 ) limited imagination and poor fantasy life , and ( 4 ) cognitive style focused on external reality . without having a good enough understanding of their mental states , these patients can not modulate emotions and instead show tendencies for direct discharge of anxiety in behavior or somatizations . interpersonal disappointments easily trigger rapid changes in mood , which an individual with certain predispositions would try to regulate by pharmacological means . a concept highly applicable to addictions , is also one of the roots of contemporary mentalization - based theories . the concept of mentalization was introduced by pierre marty in the 70s as an extension of the research into psychosomatic phenomena . classically it refers to the quality and quantity of psychic representations , their verbalization , and connections with affectivity . from another point of view that of modern developmental psychopathology fonagy [ 15 , p. 4 ] defines mentalization as a form of mostly preconscious imaginative mental activity , namely , interpreting human behavior in terms of intentional mental states ( i.e. , needs , desires , feelings , beliefs , goals , purposes , and reasons ) . this conceptualization integrates the notion of theory of mind in cognitive developmental models with attachment theory . it is based on the following three main assumptions : ( 1 ) the feeling of the self as agent is rooted in the experience of being attributed psychic states by a significant other , ( 2 ) this capability is a function of the interaction between the caring figures through a process of mirroring , ( 3 ) its development can be impaired by traumatic experiences . attachment is seen as the main factor in the development of mentalization and the formation of internal representations of affective states . secure attachment is a precondition for good enough affect regulation and guides the transition from coregulation in the mother - infant couple towards self - regulation of the child . the child internalizes mother 's empathic expression and this type of intersubjectivity is a milestone in the relation between attachment and affective self - regulation . using language , children can name their feelings , receive verbal and emotional feedback about their adequacy , and thus become supported in the effort to think about themselves and others . bateman and fonagy understand borderline personality disorder as a result of inadequate mirroring in early development . according to them , patients with borderline personality disorder have difficulty in mentalizing mainly in interpersonal and intimate situations , when they are most vulnerable to excesses in anxiety . deficits in mentalization prevent them from having a good enough buffer from affects and trigger fight or flight mechanisms . these observations are relevant for the conceptualization of addictions , having in mind the high percent of comorbidity with borderline personality disorder . intoxication impairs mentalization of own emotional states as well as those of the attachment figures . deficits in mentalization on the other hand contribute to an inclination for substance abuse under emotional stress caused by interpersonal conflicts with attachment figures . contrasting , but also complementing fonagy 's model , bouchard and lecours present a theory of mentalization focused on the development of thinking through binding of instinctual pressure in representative networks . this theory has roots in the psychosomatic research done by marty , krystal 's theory of emotions , and piaget 's conceptualization of the child 's intellectual development from sensor - motor activity towards formal verbal thought . bouchard and lecours describe a complex process of psychic working through which prevents direct discharge into actions or somatizations . affects are here conceptualized as positively or negatively valanced psychological phenomena with a somato - motor tendency for action . the authors assume that representative deficits lead to an excess of excitation , which has not been transformed into a psychic conflict , that is , anxiety has not been mentalized . forms of impulsivity , addicted behavior , and somatization are interpreted from this point of view as an expression of accumulated drive impulses with no attributed psychological meaning . bouchard and lecours describe mentalization as a continuous process , functioning as immune system of the psyche , because it modifies external and internal pressures . normally , mentalizing contributes to the coherent and meaningful experience of one 's own psychic states . instead of acquiring this tolerable distance from direct affective pressure , drug addicts often suffer from severe anxiety and depression . these conditions are triggered by the deep conviction that the individual is helpless in regulating not only external reality but also his or her emotional states . substance abuse is the coping mechanism which replaces mental processing of helplessness , apathy and emptiness , and thus brings back temporary control . bateman & fonagy , for example , point that patients with alexithymia usually grow in families characterized by high levels of negative affect , difficulties in representation , and impaired recognition of emotional expressions , as well as scant discussion of emotions in the parent - child relationship . present more specific data about the relationship between alexithymia and substance use disorders . in a sample of 204 patients ( 72 treated for alcoholism , 79 for drug addiction , and 53 for double addiction ) 41.7 % were diagnosed as alexithymic , the percentage of alexithymia being significantly higher among women ( 50 % ) than the corresponding figure among men ( 35.8 % ) . high levels of alexithymia in substance use disorders contrast low levels ( 9 % and 12 % ) among male adults and students in norm , and 8 % and 12 % among women , respectively . there is also a growing body of research supporting the foundations of mentalization theory in various clinical groups and ages . taubner et al . show that depressed patients tend to have lower reflective functioning scores concerning issues of loss compared to healthy controls . the cited research fails to show the relation between reflective functioning and symptomatology in depressed or psychotic patients . however , lecours and bouchard present data that the severity of symptoms in the borderline personality disorder is associated with low level of mentalization in two distinct areas depressive and aggressive affects . furthermore , traumatized individuals are likely to meet the dsm - iv criteria for borderline personality disorder only if they have deficiencies in mentalizing . it is clear that the complex links between severity of symptoms and quality of mentalization should be further explored . from the point of view ofthe relation between mentalization and stress , it is becoming clear that relative calmness supports mentalization , while excessive anxiety contradicts it . an evident parallel exists with addictions , where an inability to contain affects , which is a basic component of mentalization , could be used as a key psychodiagnostic characteristic . looking at this promising line of investigations , it is surprising that there is hardly any published research on drug addicted patients ' mentalizing functioning . levy and truman , however , report data showing that cocaine - using mothers ' maternal mentalization mediates associations between maternal substance abuse and children 's psychosocial development . improvement in mentalization in response to a mentalization - based parenting intervention was associated with improvement in maternal caregiving behavior and increased regulation in children between 24 and 36 months of age . examine children exposed to parental methamphetamine abuse and find that those with higher mentalization were less prone to underreport symptoms , had fewer mental health problems , and were rated by their caregivers as more socially competent . the apparent scarcity of empirical research on mentalization in addicted patients stands in contrast to the fact that the presented models have already been operationalized successfully . the most widely used instrument for mentalization assessment is the scale for reflective functioning in the adult attachment interview ( aai ) . low results on that scale are registered if the subject demonstrates poor access to the motivational origins of behavior . the grille de l'laboration verbale des affects ( geva ) offers an alternative empirical approach . it consists of two orthogonal dimensions depending on the level of mentalization : four channels of affect expression ( somatic and motor activity , imagery and labeling verbalization ) and five levels of affect tolerance and abstraction ( disruptive impulsion , modulated impulsion , externalization , appropriation , and meaning association ) . these are a total of 20 possible forms ( 4 channels 5 levels ) of affective expression . there is a common agreement that the treatment of drug addictions has to offer an encompassing range of services medical , social , and psychological . the place of psychotherapeutic work is without doubt central because it is directed at changing the psychic functioning of the patient . it is assumed that this happens through a gradual process which deepens the understanding of the place of addiction in one 's own life . it is well known that early attempts at psychotherapeutic work with addicted patients offered no base for optimism . we are familiar with these individuals ' proneness to fall into relapse and drop out of therapy , as well as low tolerance for psychic pain combined with tendency for self - destructive behavior . contemporary psychodynamic forms of treatment of personality disorders , however , show a promising approach , focused on the current mental states of the patient . aiming to create a network of representations of these internal states , mentalization - based treatment ( mbt ) follows a different path from the traditional psychoanalytic technique . it does not aim at interpreting deep unconscious fantasies but works instead with easily accessible content . the therapist 's goal is to restore mentalizing by creating representational coherence and integration of mental states . the approach that bateman and fonagy offer is well structured and focused on enhancing the working alliance and paying attention to the immediate interaction between the patient and the therapist . the therapist is flexible to the specifics of the pathology ( impulsiveness , interpersonal difficulties , self - destructive behavior , etc . ) by being relatively active and encouraging a strong relation of attachment which makes it possible for both participants to explore and overcome current failures in mentalizing . mbt explores the relationship between affect and belief and has some technical features similar to cognitive behaviour therapy , which explores the relationship between maladaptive schema and dysfunctional cognition or problematic feeling and has been widely used to treat drug addiction . of course , to the extent of focusing on the here and now patient - therapist relationship , and of placing an emphasis on transference ( albeit not interpreting it actively ) , mbt is still psychodynamic psychotherapy . this approach has already been extensively studied in several randomized control trials with patients with personality disorders . bateman and fonagy , for example , report an 8 - year followup of 41 patients with borderline personality disorder in partial hospitalization . mbt is associated with significant improvement in all measured areas ( depressive symptoms , suicidal and self - destructive behavior , number and duration of hospitalizations , social and interpersonal functioning , and use of psychopharmacological medication ) . the improvement is sustained 5 years after the end of therapy , while patients in treatment as usual show limited change or even deteriorate during the same period . this data should be considered having in mind that mbt requires relatively little additional training on top of general mental health training , and has been implemented in research studies by community mental health professionals , primarily nurses , with limited training given modest levels of supervision . this is an important aspect from the point of view of delivering cost - effective interventions . however , studies of the efficacy of this approach with drug addicted patients still have to be carried out . disorders of affect mentalization in drug addicts find different explanations in the light of the conflict - deficit dilemma . authors like khantzian stay closer to the mentalization models and see the lack of self - regulatory functions as an ego deficit , that is , a function that was never established , while , according to krystal , self - caring is forbidden by archaic parental figures . in that sense , krystal 's position is analogous to the classic psychoanalytic perspective , explaining addictions as a result of unconscious conflicts . following fonagy 's work and staying more closely with khantzian we understand low abilities for mentalization in addicted patients as a personality deficit related to early environmental failures . from this point of viewmentalization - based theories stress predominantly the relational aspects in the functioning of the patients against the intrapsychic dimension of the traditional psychodynamic theories . usually these individuals share a history of interaction with a caregiving figure , which had not provided good enough mirroring or it was discontinued due to a trauma . this focus on the direct interpersonal environment , typical for fonagy 's theorizing , however , has been criticized for an underestimation of complex object relations which modulate affect activation . indeed , de - emphasis of the unconscious is a central feature in fonagy 's theory . at the same time , as diamond and kernberg also point out , fonagy and his colleagues show significant empirical evidence that mentalization is established in the context of secure attachment and is blocked in insecure attachment and / or severe trauma . choi - kain and gunderson add several critiques to the mentalization theory based on the idea that this concept is too broad and multidimensional . however , its core measure the reflective functioning scale , yields only a single score and it is time - consuming to administer . the authors propose that research should focus on more limited concepts for which self - report measures have been developed ( i.e. , theory of mind , mindfulness , empathy , etc . ) . another limitation , according to them , in the fonagy model is emphasizing process over content . other authors ( i.e. , ) have been trying to answer the question whether the concept of mentalizing is just a new word for well - known phenomena . it becomes clear , however , that it offers a pragmatic integration of clinical observations , developmental psychopathology , and attachment experiences . last but not least , mentalization combines psychodynamic hermeneutics with evidence - based practice and is open to advances in contemporary neurocognitive theories . strength in fonagy 's mentalization model and the classically oriented model of bouchard and lecours can be regarded as genuinely integrative theories uniting the intersubjective - relational approach with the drive / conflict perspective . an important point of distinction , however , is that fonagy 's theory underlines the interaction with a real object attributing meanings to the child 's affective states , while bouchard and lecours focus primarily on the role of representative mechanisms in verbal affect mentalization . so , although the two perspectives are not completely contradictory , fundamental in bouchard and lecours ' theory are the organizing structures of unconscious subjective experience . looking at the empirical evidence , we can see that these two approaches are distinct but also overlapping . high levels of reflective functioning or elaboration of affect contribute to a basic feature of mentalization the capacity to treat behavior as driven by internal mental events and not just external stimuli . deficits in capabilities for affect representation and modulation manifested in drug - addicted patients point to similar psychogenetic origins of mentalization disorders with psychosomatic conditions . better clinical understanding of this form of pathology is a key ingredient in the assessment and clinical work with drug - addicted patients . based on a coherent understanding of personality organization , mentalization models offer promising potential for psychodiagnostic accuracy and therapeutic efficacy . their corresponding operationalized instruments can be used as valuable tools for assessment of change in psychic functioning resulting from treatment . further work is recquired on distinguishing between different subgroups in the addicted population ( i.e. , a comparison of specific impairments of the reflective function and pathways to addiction in opiate and stimulant users ) .\noutput:\n" }, { "from": "agent", "value": "traditionally treated with wariness , drug addictions have provoked a serious interest in psychodynamically oriented clinicians in recent decades . this paper discusses the development of contemporary psychodynamic conceptualizations of addictions , focusing specifically on mentalization - based theories . the concept of mentalization refers to a complex form of self - regulation which includes attribution of psychological meaning to one 's own behavior and affective states , as well as those of the others . we hypothesize that drug - addicted patients have severe impairments in mentalizing , associated with developmental deficits , characteristic for the borderline personality disorder and psychosomatic conditions . psychodynamic models of mentalization and their corresponding research operationalizations are reviewed , and implications for a contemporary understanding of drug addictions and psychotherapy are drawn . the authors propose that mentalization - oriented theories provide an adequate conceptualization , which is open to empirical testing and has clear and pragmatic guidelines for treatment ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: in this issue of critical care , leclerc and colleagues report on whether mechanical ventilation weaning predictors proposed by the task force of the american college of chest physicians ( accp ) are useful to predict weaning outcome in children . determination of predictors of weaning from mechanical ventilation in children is important , not only to reduce the risk of re - intubation and avoid delaying weaning resulting in longer paediatric intensive care unit ( picu ) stay , but also to provide clearer weaning guidelines , especially as there is an increasing trend for weaning and extubation to be carried out by nursing staff . in addition , . found that picu patients failing extubation had longer length of picu stay ( 17 versus 7 days ) , and a significantly higher mortality ( 4 % versus 0.8 % ) . in adult intensive care , there are established indices predicting the outcome of trials of weaning from mechanical ventilation , such as the rapid shallow breathing index . these were established to identify the earliest time that a patient can resume spontaneous breathing and they also appear to apply if performed immediately pre - extubation . major efforts have been made to identify parameters that can predict extubation failure in children , but a clearly defined set of risk factors has not yet been established . leclerc et al . also found that the accp adult criteria were poor predictors of weaning outcome in children . there are several possible reasons for this discrepancy between adult and paediatric studies . in the adult studies , the length of mechanical ventilation and failed weaning rate are higher than in children , thus possibly allowing identification of risk factors using smaller numbers of patients . in the adult studies , the median length of ventilation was 8 to 11 days , and weaning failure rates were 40 % . in paediatric studies , the length of mechanical ventilation is generally much shorter , being two days or less in most children . in the study by leclerc et al . , the median length of ventilation was 4 days , and the weaning failure rate was 20 % , indicating that much larger numbers of paediatric patients may be required to detect a significant difference . most of the adult studies were carried out when the patients were clinically stable and the primary physician considered them ready to undergo a weaning trial . in the current study , patients had already been weaned to pressure support ventilation 15 cmh2o , a positive end expiratory pressure ( peep ) of 5 cmh2o and inspired oxygen fraction ( fio2 ) of 0.4 and only patients who passed a spontaneous breathing trial were included . thus , the authors may have pre - selected a group of patients who had already met all the clinical criteria for weaning , and were at low risk of weaning failure , thereby reducing the power of their study measurements . studied 418 children also with fio20 .4 and peep 5 who underwent a spontaneous breathing trial with t - piece or low level pressure support , and even when the 95 patients who failed the spontaneous breathing trial were included , they found that the ability of traditional weaning indices to discriminate between patients who could be extubated and those who could not was still very poor . in contrast , venkataraman et al . studied 312 children immediately prior to extubation , but did not have a minimum ventilation requirement prior to extubation , and they were able to establish threshold values for a low ( 10 % ) and high ( a spontaneous tidal volume 3.5 ml / kg due to low respiratory drive or increased load , and patients extubated from a higher level of ventilator support ( fio20 .4 , mean airway pressure 8.5 cmh2o ) were more likely to fail extubation . thus , the low patient numbers ( 56 patients ) and a requirement for fio20 .4 , peep 5 cmh20 and a passed spontaneous breathing trial may have contributed to the difficulty in detecting a significant difference in leclerc et al . 's study . adult weaning indices are designed to quantify the extent of rapid shallow breathing ( rapid spontaneous respiratory rate ( f ) , low spontaneous tidal volume ( vt ) and poor inspiratory effort ( inspiratory occlusion pressure ) ) as this is a common finding in adult patients who fail weaning . when these indices are applied to children , venkataraman et al . and farias et al . found that integrated indices such as f / vt and the compliance rate oxygenation and pressure index do not account for normal developmental changes in respiratory function , including mechanics and gas exchange and , therefore , are poor predictors of extubation success in infants and children . leclerc et al . again found that they performed poorly , even when the paediatric adjusted version of rapid shallow breathing ( tidal volume and dynamic compliance corrected for the patient 's body weight ) is used . this still does not take into consideration age related changes in spontaneous respiratory rate , and that not all paediatric patients develop tachypnoea prior to weaning failure . in some children , bradypnoea occurs , especially if oversedation is the primary reason for a low inspiratory drive . another possible factor to account for the difficulty in predicting weaning outcome in children is the heterogeneity of mechanically ventilated children . in leclerc . 's study , the causes of re - intubation included respiratory failure due to spinal amyotrophy , myopathy , and mucopolysaccharidosis , three patients with pulmonary oedema , and two with bronchial obstruction . thus , the reason for weaning failure may be disease specific in some of these children , and may be difficult to detect using respiratory function measurements alone . it is thus unlikely that a single parameter or index predicting weaning outcome will be found , although larger studies may determine a ' universal set ' of extubation failure predictors . for example , low spontaneous tidal volume has been found to be predictive of extubation failure in the majority of published paediatric studies where it was measured . multiple studies have also noted that young age , prolonged ventilation support and prolonged use of sedative / analgesic drugs are risk factors for re - intubation . our challenge still remains to find simple easy to measure risk factors that will accurately define the group of paediatric patients at high risk of extubation failure . accp = american college of chest physicians ; f = rapid spontaneous respiratory rate ; fio2 = inspired oxygen fraction ; peep = positive end expiratory pressure ; picu = paediatric intensive care unit ; vt = low spontaneous tidal volume .\noutput:\n" }, { "from": "agent", "value": "prediction of ventilation weaning outcome in children is important , as unsuccessful extubation increases both morbidity and mortality . adult weaning criteria are poor predictors of weaning outcome in children for several possible reasons : the length of mechanical ventilation is generally much shorter , and the weaning failure rate is lower in children ( thus larger patient numbers are required ) ; integrated weaning indices , such as the rapid shallow breathing index , do not account for normal developmental changes in respiratory function ; and the heterogeneity of mechanically ventilated children is greater than in adults . the challenge remains to find universal weaning outcome predictors in children ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: for early detection of arteriosclerotic disease , several parameters for assessing vascular nature have been used . the pulse wave velocity ( pwv ) is one of these parameters and has been widely used mainly in the field of internal medicine , especially in the prediction of cardiovascular events . however , carotid - femoral pwv requires somewhat complicated technique to obtain an accurate waveform . brachial - ankle pwv has been developed , which is reported to be correlated with carotid - femoral pwv and can be measured with a simpler technique . however , it was pointed out that both carotid - femoral pwv and bapwv were strongly affected by the changes in blood pressure during measurements . for the purpose of using pwv as an indicator of vascular vessel wall stiffness , recently , a new index of vascular stiffness , the cardio ankle vascular index ( cavi ) , was developed . considered to be an index independent of blood pressure , cavi is a parameter of adjusted pwv for blood pressure , based on a stiffness parameter using bramwell - hill 's formula . cavi is calculated as follows : ( 1 ) cavi = a ( 2p ) ln ( pspd ) pwv2 + b , where ps indicates systolic pressure in brachial artery ; pd , diastolic pressure in brachial artery ; , density of blood ; a , b , correction coefficient . the usefulness of cavi in the management of patients with hypertensive , diabetic or renal disorders was previously reported in , but we found no reports on cavi in pregnancy . in our current study , we assessed cavi in normotensive and hypertensive pregnant women . we believe that this is the world 's first report on cavi in pregnancy . the subjects of this study were 109 japanese women consisting of 23 nonpregnant healthy women ( group a ) , 45 normotensive pregnant women ( group b ) , 28 pregnant women complicated with established preeclampsia ( group c ) , and 13 pregnant women with chronic hypertension ( group d ) . eighty - six pregnant women ( groups b , c , and d ) were patients who visited mie university hospital . twenty - three nonpregnant women ( group a ) were volunteers including nurses and midwives in mie university hospital . the diagnosis of preeclampsia was made according to the criteria of the international society for the study of hypertension in pregnancy , which includes a blood pressure 140/90 mmhg and 300 mg of protein in a 24 - hour urine collection . chronic hypertension was defined as hypertension diagnosed prior to conception or within the first 20 weeks of pregnancy . the women in group d did not have superimposed preeclampsia . in some cases , the blood pressure recorded during the cavi examination was lower than the criteria value . the women in group c were normotensive in the first trimester of pregnancy and the blood pressure returned to normal by 12 weeks postpartum . no significant differences were noted in the gestational week and maternal age among the four groups . all the subjects in group a were uncomplicated and uneventful throughout the course of pregnancy and puerperium . the cavi is based on the stiffness parameter ( ) , which expressed blood pressure independent vascular stiffness . stiffness parameter ( ) is calculated as follows : ( a ) = [ ln ( pspd ) ] ( dd ) . ln indicates natural log ; ps , systolic pressure ; pd , diastolic pressure ; d , vascular diameter ; d , change of vascular diameter . the relationship between volume elastic modulus and pwv is expressed by bramwell - hill 's formula , and the relationship between vessel volume and diameter is given when a cylindrical model is used : ( b ) z2 = ( p ) ( vv ) ( bramwell - hills formula ) , ( c ) vv = d2d . z indicates cardioankle pwv ( m / sec ) ; p , pulse puressure ; , blood density ( 1.0310 kg / m ) ; v , volume of blood vessel ; v , change of v. the previous 3 formulas ( a , b , and c ) give the following equation : ( 2 ) = ( 2p ) [ in ( pspd ) ] z2 . thus , the stiffness parameter ( ) can be easily calculated by measures of bp and cardioankle pwv . the new index cavi is expressed as follows : ( 3 ) cavi = a + b . a and b indicate the constants to convert to a value that is approximate to conventional aortic pwv for each patient compatibility . cavi is easily measured using vasera vs - 1000 ( fukuda denshi , tokyo , japan ) , which is now becoming popular . the cavi is automatically calculated by the instrument and reflects the stiffness parameter ( ) . the cavi has the great merit that it is not influenced by bp , whereas conventional pwv is strongly influenced by bp . however , cavi might have an error because of the variety of blood density in each case , where in the formula for calculation of cavi , a standard value of blood density was used . the subject was placed in the supine position and blood pressure : bapwv and cavi were recorded using a vascular screening system vasera vs - 1000 ( fukuda denshi , tokyo , japan ) . in all cases , no symptomatic adverse effectsmann - whitney 's u - test was used for statistical analysis of comparing values between the two groups . probability ( p ) values less than .05 were considered as significant . the values of blood pressure shown in table 1 were those recorded during the cavi examination and in some cases the values were lower than the criteria values . mean gestational age of group b was lower than those in groups c and d , but no significant differences were noted among groups a , b , c , and d in the maternal age , and no significant differences were noted among groups b , c , and d in the gestational age . significant differences were noted between groups a and c , a and d , b and c , b and d in systolic , diastolic and mean blood pressures . as shown in figure 2 , bapwvs in groups a , b , c , and d were 1087132 cm / sec , 1119183 cm / sec , 1446224 cm / sec , and 1614225 cm / sec , respectively . significant differences were noted between groups a and c , a and d , b and c , b and d in bapwv . cavi in groups a , b , c , and d were 7.10.4 , 7.10.5 , 8.41.0 , and 9.81.8 , respectively . similar to bapwv , significant differences were noted between groups a and c , a and d , b and c , b and d in cavi . to assess the vascular stiffness , several parameters have been used such as carotid - femoral pwv , bapwv , sp , and augmentation index ( ai ) . carotid - femoral pwv is affected by blood pressure and can be adjusted using a compensating nomogram for blood pressure . however , carotid - femoral pwv requires somewhat complicated technique to obtain an accurate waveform . it is also time - consuming , and it takes approximately 15 to 20 minutes for one measurement . bapwv has been developed , which can be assessed with a simpler technique in a short time using a measurement system but it is strongly affected by the changes in blood pressure during measurement . ai is strongly influenced by heart rate , and it is necessary to correct ai by heart rate for the comparison among subjects . sp is a parameter which is independent of blood pressure but requires a long time for the measurement , and the measuring equipment for sp ( sonographic vessel tracking system ) is expensive . moreover , sp is a parameter of the local vessel ( usually the abdominal aorta or common carotid artery is used for the measurement ) and not a systemic vessel parameter . cavi is thought to be an index which eliminates these defects in the conventional vascular parameters . it is a noninvasive method and the repeated measurement during pregnancy is possible . in our current study , we found no complications in the subjects related to cavi measurements , including pregnant women themselves . in preeclamptic women , no atherosclerotic change of the vessel wall was produced , which is different from the vessel wall in chronic hypertensive women . in our current study , both in preeclamptic and chronic hypertensive groups , bapwv was elevated and no significant difference was noted between the two groups . on the other hand , cavi was also elevated both in preeclamptic and chronic hypertensive groups , but the elevation was milder in the former group . blood pressure was elevated and ( at least partially ) structural change in the vessel wall may have been produced , resulting in both bapwv and cavi elevations . in preeclamptic women , blood pressure was elevated and thus bapwv was elevated . in preeclamptic women , lesser vesselwall structural change was produced , and lesser elevation of cavi was seen , which is lesser influenced by blood pressure elevation than bapwv . from our results , we believe that we can distinguish the vessel structural change between chronic hypertension and preeclampsia through bapwv and simultaneous cavi measurements . however , if cavi could be completely independent of blood pressure and could completely reflect the atherosclerotic change of the vessel wall , it might be difficult to explain the reason of significant elevation of cavi in preeclampsia from normotensive pregnancy . brodszki and colleagues reported that there were no differences in vessel wall stiffness between women with preeclampsia and healthy controls , through the assessment of common carotid artery , abdominal aorta , and popliteal artery by using ultrasonic echo - tracking system . on the other hand , ong and colleagues reported that structural change was observed in myometrial radial arteries in women with preeclampsia . thus , we hypothesize that cavi might reflect the minimal change of the vessel wall , which caused the elevation of cavi in preeclamptic women . further work is in progress to evaluate the usefulness of cavi in the management of preeclampsia . recently , cavi , a new index of vascular stiffness , was developed , which is thought to be an index independent of blood pressure . we assessed cavi in normotensive and hypertensive pregnant women as the world 's first report on cavi in pregnancy . we believe that we can distinguish the vessel structural change between chronic hypertension and preeclampsia through simultaneous bapwv and cavi measurements .\noutput:\n" }, { "from": "agent", "value": "it was previously reported that the brachial - ankle pulse wave velocity ( bapwv ) is elevated in preeclamptic women . however , bapwv is strongly affected by blood pressure . recently , a new index of vascular stiffness , the cardioankle vascular index ( cavi ) , was developed . cavi is thought to be an index independent of blood pressure . we assessed cavi in normotensive and hypertensive pregnant women . we studied a total of 109 japanese women consisting of 23 nonpregnant healthy women ( group a ) , 45 normotensive pregnant women ( group b ) , 28 pregnant women complicated with established preeclampsia ( group c ) , and 13 pregnant women with chronic hypertension ( group d ) . the subject remained supine while the blood pressure , bapwv , and cavi were recorded . no significant difference in bapwv was present between groups c and d , but the difference in cavi was significantly high in group d. we believe that we can distinguish the vessel structural change between chronic hypertension and preeclampsia through simultaneous bapwv and cavi measurements ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the main etiologic agents in bacterial conjunctivitis are haemophilus influenzae , staphylococcus aureus , or steptococcus pnuemoniae . these infections are often self limiting . antibiotics are used with infectious bacterial conjunctivitis to speed recovery , reduce complications , and prevent reinfection . physicians need choices to overcome the limitations of frequent dosing , compliance , and bacterial resistance with current antibiotic regimens . this review provides an update on the clinical development of 1 % azithromycin formulated with durasite ( insite vision , alameda , ca , usa ) , an innovative ocular delivery system that was used to deliver high bactericidal concentrations of azithromycin to the eye to treat bacterial conjunctivitis . new ocular antibiotics are needed to keep pace with the increasing incidence of bacterial resistance and to provide patients with a regimen that decreases their overall treatment burden and improves the chances for adherence to the treatment . standard topical vehicles such as eyedrops , ointments , and gels are all highly effective for treating ocular surface infections , although eyedrops may be more practical than ointments for daytime use as ointments may interfere with vision . an ideal topical treatmentwould have the convenience of a drop but the long - term duration of an ointment . antibiotic eyedrops are often used to treat acute infectious diseases and speed recovery , reduce sequelae , and prevent the spread of pathogens through the community . in addition , prophylaxis with topical antibiotics is a prudent and necessary step to reduce the risk of infection and improve outcomes following ophthalmic surgery or ocular trauma ( batequet 2001 ; de kaspar 2004 ) . powerful medications such as 0.5 % moxifloxacin ( vigamox ; alcon , inc , fort worth , tx , usa ) and 0.3 % gatifloxacin ( zymar ; allergan , inc , irvine , ca , usa ) increase the number of potential treatment choices available to clinicians . however , in order to sustain critical bactericidal concentrations of these drops in the eye , dosing requirements range from 3 to 8 drops a day ( table 1 ) ( allergan inc . 2004depending on the patient s history , ophthalmologists choose from an array of old and new antibiotics for the management of ocular surface infection . newer broad - spectrum antibiotics may be more desirable than some of the older , narrower - spectrum drugs . however , even with the improved activity of newer generation fluoroquinolones , surveillance studies and regulatory agencies have reported changing trends in the susceptibility of infecting organisms to fluoroquinolones ( goldstein et al 1999 ; venezia et al 2001 ; ambrose et al 2004 ) . documentation of methicillin resistance has also shown an increase in frequency ( shanmuganathan et al 2005 ) . indiscriminate and incorrect ophthalmic usage of these powerful broad - spectrum anti - infectives can promote the development of resistance . there is still a great need in ophthalmology for broad - spectrum antibiotics that can fill the coverage gap created by fluoroquinolone - resistant bacteria . azithromycin is a semi - synthetic antibiotic that has been successfully used in oral and intravenous dosage forms to treat gram positive - , gram negative - , and atypical infections of the skin and upper respiratory tract ( figure 1 ) . azithromycin is derived from erythromycin and has been available under the trade names zithromax in the united states , western europe , and japan ( pfizer , inc . , new york , ny , usa ) and sumamed in eastern europe ( pliva , sarajevo , bosnia and herzegovina ) . compared with the narrower - spectrum macrolide erythromycin , azithromycin , an azalide , is characterized by improved oral bioavailability , increased tissue penetration and persistence , and a longer elimination half - life ( piscitelli et al 1992 ; girard et al 1993 ) . the pharmacokinetic properties of azithromycin enable short and simple daily dosage regimens that can contribute to greater patient compliance ( pfizer , inc . indicate that azithromycin is highly concentrated within polymorphonuclear leucocytes , which gravitate by chemotactic mechanisms to sites of infection . the high intracellular concentration of azithromycin in inflammatory fluids of abscesses supports the pharmacodynamic properties , which include concentration - dependent killing of bacteria and prolonged persistent effects in tissues ( amsden 2001 ; pfizer , inc . the primary antibacterial effect of azithromycin differs from that of fluoroquinolones and involves inhibition of protein synthesis and binding of the 50s ribosomal subunit ( champney and miller 2002 ; mabe et al 2004 ) . compared with older antibiotics , both azithromycin and the fluoroquinolones gatifloxacin and moxifloxacin are effective against gram negative - , gram positive - , and atypical bacteria ( allergan inc . both drug classes have a well known efficacy profile , but systemic use of fluoroquinolones is not recommended as a first - line anti - infective in young children ( committee on infectious diseases 2006 ) . until recently , ophthalmic uses of azithromycin were limited to oral dosing for the treatment of chlamydia trachomatis infections . the safety of three - dose ( once per week for 3 weeks ) and single - dose regimens has been demonstrated in clinical trials ( west 1999 ) . in comparison trials , a single 1 - g dose of azithromycin was just as effective as a standard 10 - day treatment with doxycycline ( 100 mg twice daily ) in the treatment of adult inclusion conjunctivitis ( katusic et al 2003 ) . comparative corneal penetration studies in animals indicate that aqueous formulations of azithromycin created by reconstituting the intravenous dry form of the drug achieved higher tissue penetration than the related azalide clarithromycin ( kuehne et al 2004 ) . reconstituted azithromycin , although effective and capable of penetrating the cornea , is not suitable as a commercial eyedrop because it lacks long - term chemical stability and its sterility is not preserved in the bottle ( pfizer , inc . it is a lightly cross - linked bioadhesive polymer of polyacrylic acid suitable for medical applications that require topical delivery and sustained release . the topical formulation of 1 % azithromycin in durasite ( azasite ; insite vision ) is a gel - forming solution that entraps water and the active molecules in a bioadhesive matrix . azithromycin is then held within the matrix by continued physical entrapment and reversible ionic interaction . in eyedrop formulations with durasite , drug delivery can be sustained , with release from the matrix taking place over a period of up to 6 hours ( keller et al 1993 ; harper et al 1995 ) . initial pharmacokinetic modeling studies of the conjunctival concentrations achieved with a regimen of once - a - day dosing for 5 days indicated that peak concentrations of 150200 g / g and trough concentrations of 40 g / g could be sustained during a 24 - hour period ( figure 2 ) . these concentrations obtained from once - a - day dosing are several fold higher than the minimum inhibitory concentrations ( mics ) needed to fight most ocular surface infections . this is of clinical value for patients who are poorly compliant with multi - dose eyedrop regimens . even with these trough concentrations , a therapeutic level of azithromycin can be maintained throughout the night with once - a - day dosing . evaluation of the safety and efficacy of 1 % azithromycin in durasite was recently completed in a controlled phase 3 clinical trial for bacterial conjunctivitis . clinical and bacteriologic confirmation of infection was obtained for the worst affected eye at study entry and exit . in most cases , only one eye was treated , but the fellow eye could be treated if the infection spread . two masked trials were run simultaneously in which the efficacy and safety of a 5 - day regimen of 1 % azithromycin in durasite was compared with a 5 - day regimen of 0.3 % tobramycin eyedrops or vehicle , dosed 4 times per day . subjects in both treatment groups received 20 drops of masked study medication . those who completed the azithromycin arm of the trial received a combination of active drug and vehicle - only drops . a loading dose of the active azithromycin eyedrop was administered twice a day on days 1 and 2 and once a day on days 3 through 5 . clinical resolution was defined as the absence of clinical signs and symptoms of bacterial conjunctivitis , specifically conjunctival discharge , bulbar conjunctival injection , and palpebral conjunctival injection at study exit ( visit 3 , day 6 ) . at the test - of - cure visit on day 6 , the efficacy data demonstrated that the clinical resolution rates of 1 % azithromycin in durasite were superior to vehicle ( 63.1 % vs 49.7 % ; p = 0.030 by fisher exact test ) and equivalent to 0.3 % tobramycin ( 79.9 % vs 78.3 % ; p = 0.783 ) . the most frequently observed ocular adverse events seen in 1 % to 3 % of the overall study population were eye irritation , conjunctival hyperemia , and worsening conjunctivitis usually seen as transfer of infection to the fellow eye during treatment ( table 2 ) ( abelson et al 2006a , b ) . upon analysis of tolerability , bacterial eradication was demonstrated as the absence of suprathreshold levels of new pathogens in cultures taken at study exit . the results of the exit visit cultures were compared with those obtained at the baseline visit . bacterial eradication with 1 % azithromycin in durasite was just as robust as with 0.3 % tobramycin ( 88.1 % vs 94.3 % , p = 0.073 ) . the most frequently observed bacteria upon study entry were s. aureus , s. pneumoniae , and h. influenzae . the minimum inhibitory concentrations against these bacteria ranged from 0.12 to 1024 g / ml ( table 3 ) . more importantly , the data showed that the antibacterial spectrum of azithromycin in durasite included several species that were resistant to azithromycin . resistance was defined by the systemic breakpoints as assessed by the clinical laboratory and standards institute ( clsi ) . table 4 lists clinical isolates that were resistant when grown in cultures to 1 % azithromycin as determined by the mic but susceptible to 1 % azithromycin in durasite as evaluated by the absence of ocular pathogens at the end of the study . the bacteria were isolated from study participants and evaluated for susceptibility to azithromycin at visit 1 ( day 1 ) . at the point - of - cure visit ( day 6 ) , the data showed that 1 % azithromycin in durasite eradicated 21 of 29 resistant bacterial species ( 72.4 % ) . this result suggests that the clsi systemic breakpoints may not be a fair representation of antibiotic activity with topical dosing and that the antibiotic effect of azithromycin may have been enhanced by the formulation of the azalide in durasite . a 1993 review of cultured pathogenic organisms in children found that 80 % of conjunctivitis cases were bacterial infections , 13 % were viral , 2 % were allergic , and 5 % had unidentifiable causes ( gigliotti et al 1981 ; weiss et al 1993 ) . according to a review by lichtenstein and colleagues the most common pathogens that cause bacterial conjunctivitis in children are h. influenzae , s. pneumoniae , and moraxella catarrhalis ( lichtenstein 2003 ) . in the us , and less often in the uk , children with bacterial conjunctivitis may be excluded from the school setting until adequate intervention has been used to prevent contagion ( american academy of pediatrics 2003 ; health protection agency 2006 ) . sometimes adequate intervention is problematic with currently available prescription therapies that call for 38 doses per day because doses may be skipped or taken improperly . currently in the us , fluoroquinolone , aminoglycoside , or the combination of polymyxin b sulfate and trimethoprim sulfate in an ophthalmic solution are the most widely prescribed ocular anti - infectives for bacterial conjunctivitis in children ( lichtenstein 2003 ; schuman 2003 ) . although similar data on the use of ocular solutions in canada are not currently available , the most frequently dispensed antimicrobials by retail pharmacies in canada are extended - spectrum penicillins ( 25 % ) , macrolides ( 20 % ) , tetracyclines ( 14 % ) , fluoroquinolones ( 12 % ) , and second - generation cephalosporins ( 5 % ) ( public health agency of canada 2004 ) . in the united kingdom , a 5 - day regimen of chloramphenicol ointment or drops ( 1 drop every 2 hours on days 1 and 2 , and 1 drop every 4 hours on days 3 through 5 ) is available to treat ocular surface infections . an over - the - counter formulation of chloramphenicol was recently made available for the treatment of bacterial conjunctivitis . however , nursing studies have challenged its effectiveness and safety in children ( harkless 2006 ) . additionally , results from a controlled clinical trial in the uk indicated that chloramphenicol was no more effective than placebo ( everitt 2006 ) . alternative narrow - spectrum approaches involving preparations of fusidic acid that can be dosed twice daily for 510 days are also being investigated for bacterial conjunctivitis . the formulations are viscous so the drug can stay in contact with the conjunctiva longer than traditional drops ( jackson et al 2002 ; doughty and dutton 2006 ) . when all options have been considered , the dosing regimen for 1 % azithromycin in durasite appears more favorable than the currently available choices in the uk and us . in the clinical study , a regimen of 7 drops of 1 % azithromycin in durasite ( 2 drops on days 1 and 2 and 1 drop on days 3 through 5 ) was found to be equally effective as 20 drops of tobramycin ( 65 % more drops ) . upon approval of 1 % azithromycin in durasite by the food and drug administration , the duration of dosingwill most likely be extended to 7 days as it has been with all recently approved ocular anti - infectives . in either case , this dosing regimen lowers the treatment burden on parents and caregivers and increases the probability of real - world compliance and successful treatment outcomes . azithromycin provides excellent coverage of the pathogens that are the most common cause of bacterial conjunctivitis in adults , s. aureus , h. influenzae , and s. pneumoniae ( morrow and abbott 1998 ) , and its combination with the bioadhesive properties of durasite may enhance its antibiotic effect against microbes that were commonly considered resistant to azithromycin . for example , although other bacteria may be involved , staphylococcus species are prevalent in many patients with chronic bacterial conjunctivitis . this type of conjunctivitis often develops in association with blepharitis , a common but often unrecognized inflammatory condition related to bacterial colonization of the eyelid margins . in adults , the work - up of patients with chronic conjunctivitis and blepharoconjunctivitis involves culturing the conjunctiva and the eyelid margins to identify the predominant bacterial pathogen . treatment includes the establishment of good eyelid hygiene , using warm compresses and eyelid margin scrubs and the application of appropriate topical antimicrobials ( eg , erythromycin or sulfacetamide ointment ) for 12 weeks ( morrow and abbott 1998 ; american academy of ophthalmology 2003 ) . twenty - four - hour coverage with ointments may be difficult to achieve since their use can cause blurriness , thereby making daytime application inconvenient for patients . the gel - forming eyedrop of azithromycin in durasite drop provides the desired long - term residence time in the eye and in clinical trials . in the trial ,1 % azithromycin in durasite eliminated 82 % of s. aureus , including some species that are considered resistant to azithromycin . formulations of sustained - acting drugs in durasite have been evaluated before . in these cases as well as with azithromycin , blurriness from the formulation was not a major safety finding ( harper et al 1995 ) . there are several compelling reasons why 1 % azithromycin in durasite will be a welcome addition to the class of ophthalmic antibiotics ; it offers a simplified dosing regimen that is convenient and effective , the potential for increased compliance and successful therapeutic intervention because therapy can be completed with 7 drops administered over 5 days , and high bactericidal levels that can be sustained in the eye overnight , and the potential for reduction in the development of resistance by effectively killing sensitive organisms .\noutput:\n" }, { "from": "agent", "value": "conjunctivitis , or inflammation of the conjunctiva , refers to a diverse group of ocular surface diseases of viral or bacterial origin that primarily affect the conjunctiva . in developed countries , the most common causative bacterial pathogens are staphylococcus aureus , haemophilus influenzae , and streptococcus pneumoniae . most varieties of conjunctivitis are self - limiting ; however , some cases can be extremely contagious or cause serious complications if left unchecked . new ocular antibiotics are needed to keep pace with the increasing incidence of bacterial resistance and provide options that decrease the overall treatment burden and encourage patient compliance . azithromycin is a well known systemic anti - infective with broad spectrum activity against gram positive - , gram negative - , and atypical bacteria species . ocular use has been limited because its solubility and stability profiles in aqueous media were not favorable for delivery to the eye . an eyedrop of 1 % azithromycin in durasite ( azasite , insite vision , alameda , ca , usa ) , a bioadhesive ocular drug delivery system , was recently developed and evaluated in clinical trials . this formulation is well tolerated , delivers a high concentration of azithromycin to the conjunctiva , has a broader eradication profile than aqueous azithromycin , and can be effectively dosed with 7 drops , a 65 % reduction in the amount of drops required by the most popular antibiotics currently used for conjunctivitis ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: the diagnostic and statistical manual of mental disorders ( dsm - iv - tr ) includes panic disorder ( pd ) with agoraphobia among its list of anxiety disorders . panic attacks are described as a period of intense fear or anxiety accompanied by somatic and psychological symptoms . these symptoms include a lack of breath , tachycardia , fainting , perspiration and trembling . agoraphobia is associated with psychological anxieties including a fear of losing control , fainting , dying , being in crowded areas , travel , and feeling ill in public places . nomophobia is the modern fear of being unable to communicate through a mobile phone ( mp ) or the internet . is derived from the expression no mobile phobia , that is , the phobia of being without an mp . nomophobia is a term that refers to a collection of behaviors or symptoms related to mp use . nomophobia is a situational phobia related to agoraphobia and includes the fear of becoming ill and not receiving immediate assistance . because people s relationships with mps , computers and other technology profoundly influence interpersonal behaviors and social habits , these relationships should be continuously monitored and studied . communication technologies modify people s interaction with the world , their perception of reality and their interactions with time and space . mps facilitate individual communication processes and provide a degree of mobility that allows their users to be reached at any time . moreover , mps allow people to connect with others wirelessly and without a physical local network . the miniaturization of communication technologies permits an extensive amount of flexibility , mobility and personalization . these portable technologies express the values of freedom of choice , will and action and ultimately emphasize individuals over collectives . mps are attractive because they allow users to browse the internet , work with people from a distance , speak with friends and colleagues , resolve problems and render services without leaving their current location . because new technology facilitates each of these functions , it leads to the widespread acceptance of and excitement about these devices . the literature reveals that , due to the specific characteristics of their disease , patients with pd are more anxious and worried about various daily issues than healthy people . people with agoraphobia fear public places and the inability to receive immediate aid may be responsible for developing an excessive attachment to an mp among this particular population . in these cases , an mp makes people with anxiety disorders feel more secure as an mp allows them to be rescued from an attack . healthy people also depend on mps for work and socializing ; however , they do not despair or become nervous when they are unable to make a call or connect to the internet . based on the characteristics of anxiety disorders , we began to observe that people with this condition are dependent upon certain types of technologies , including mps . specifically , the absence of these devices cause distress and anxiety in individuals with anxiety disorders . the present study hypothesized that people with pd and agoraphobia would show more emotional alterations and symptoms related to the absence of their mps than would healthy people . the mp may have a potential role as a safety signal for agoraphobic pd patients . the importance of safety signals and safety - seeking behavior in those with anxiety disorders in general , and pd with agoraphobia specifically , is a topic receiving considerable attention in the cognitive behavioral literature . this study describes the participants routine use of mps and examines the possible appearance of emotional alterations and symptoms related to the daily use ( or lack thereof ) of the mp . participants included a group of patients with pd and agoraphobia and a control group consisting of people without any psychiatric disorders . this quantitative and descriptive study employed a consecutive sample of volunteers consisting of 50 patients with pd with agoraphobia and 70 control volunteers with no psychiatric disorders . psychiatrists at the laboratory of panic and respiration ( labpr ) of the institute of psychiatry ( ipub ) within the federal university of rio de janeiro ( ufrj ) diagnosed the patients according to the diagnostic criteria of dsm - iv - tr , and a complementary clinical evaluation tool , the mini international neuropsychiatric interview ( mini ) version 5.0.0 , evaluated psychiatric disorders . group 1 consisted of patients with pd with agoraphobia , and group 2 was made up of the 70 control participants . we recruited all members of the later group from the staff and students of the institute of psychiatry and non - family caregivers of the patients . the control group was heterogeneous with regard to age , education , occupation and sex . the control participants underwent psychiatric evaluations and completed the mini to rule out the presence of mental disorders . the criteria for inclusion in the control group consisted of being between 18 - and 70 - years of age , literate , residents of rio de janeiro and mp owners . all volunteers signed a terms of free and clarified consent form and attended to instructions regarding the study s procedures . to assess participant nomophobia , we conducted an extensive literature search for a tool that provides good psychometrics ( i.e. , validity and reliability parameters ) for studies conducted in brazil . we did not find such an instrument nor could we find a nomophobia measure validated for other cultures . an extensive review of nomophobia raised major issues that permeated the relationship between people and their mps , as well as their reactions arising from the loss of their mps . these questions were based on the nomophobia literature as well as sociodemographic data , mp routines , dependence upon mps , and the possible symptoms and emotions related to the daily use of mps ( or lack thereof ) . two psychiatrists initially created the questionnaire , which was then sent to two other clinicians who acted as judges and offered suggestions for its improvement . the creators discussed all suggestions with a third psychiatrist who was nave to the instrument . a consensus decided that 29 questions were adequate to address nomophobia . a pilot study consisting of seven patients ( who were not part of the group of study patients ) with varying levels of education completed the questionnaire to determine whether the questionnaire was comprehensible . the patients and the data from the pilot study were not considered in the full study . thus , we prepared the 29 - item , self - report , objective response questionnaire concerning mp use as an evaluation instrument ( table 1 ) . we report age as the means and standard deviations . the chi - squared test with a 95 % confidence interval and a p - value 0.05 detected statistically significant differences between the groups with respect to the nonparametric variables . considering the large number of variables analyzed , the bonferroni correction was applied , and the nominal significance level was determined to be p = 0.002 . to study participant - expressed symptoms and emotions and to understand the contribution and weight of each variable in separating the group , we used the multivariate method of canonical correlation analysis for dichotomous variables . socio - demographic data indicated that the average age of group 1 participants was 43 years and the average age of individuals in group 2 was 35 years ; the percentages of females and males in group 1 were 76 % and 24 % , respectively , and 68 % and 31 % , respectively , in group 2 . in both groups , the level of schooling of individuals ranged from primary to university , and 99 % of all participants were employed . table 2 describes participants routine mp use . in general , the symptoms ( anxiety , trembling , perspiration , tachycardia , respiratory alterations , depression , panic , fear ) or emotions ( comfort , agitation , disorientation , dependence , rejection , low self - esteem , loneliness , insecurity ) due to not having access to an mp were significantly different between the participants with pd and the control group ( = 13 , 314 , df = 1 , p 0.001 ) . table 3 describes the anxiety and depressive symptoms in subjects across the groups , whereas table 4 reports the emotions associated with mp use ( or lack thereof ) . we also recorded the participant s current state of mind during the test , and a chi - squared test measured the degree of significance of these differences between groups . all the elements measured in table 2 differed significantly between the groups . with regard to the results in table 4 , we only found significant between - group differences for loneliness and self - esteem . to better understand the relationship between participant - reported symptoms and emotionsthe canonical discriminant analysis of the participant - reported symptoms provided a single function with an eigenvalue = 0.40 and a canonical correlation = 0.53 . the results indicated that a single dimension explains the difference between the groups . in assessing the relative contribution of each variable s linear combination to the standardized canonical discriminant function coefficients , we noted that the order to which the variables contributed was anxiety ( 0.54 ) , sweating ( 0.351 ) , panic ( 0.269 ) , tremors ( 0.262 ) , depression ( 0.09 ) and changes in respiration ( 0.07 ) . fear was the only variable that lost statistical weight ( -0.18 ) . in assessing the weight of each variable in the group through the values obtained by the structure matrix , we noted that the order of importance variable for differentiating the groups was anxiety ( 0.74 ) , sweating ( 0.67 ) , panic ( 0.57 ) , tremors ( 0.56 ) , changes in respiration ( 0.483 ) , depression ( 0.44 ) , tachycardia ( 0.40 ) and fear ( 0.12 ) . after examining the functions at the group centroids , we realized that the two groups were discriminated by the symptoms presented with values of 0.74 for patients with pd and -0.53 for controls . the examination of participant - reported emotions across the groups revealed an eigenvalue of 0.281 with a canonical correlation of 0.47 and a wilks ' lambda of 0.781 ( df = 8 , p 0.001 ) . the standardized canonical discriminant function coefficients were 0.53 for loneliness , 0.40 for self - esteem , 0.29 for rejection , 0.36 for disorientation , -0.30 for agitation , -0.09 for dependency and -0.47 for insecurity . the weights of each variable on the structure matrix were 0.58 for self - esteem , 0.54 for rejection , 0.53 for loneliness , 0.36 for comfort , 0.28 for disorientation , 0.18 for agitation , -0.09 for insecurity and -0.07 for dependency . an evaluation of the functions at the group centroids revealed that the groups were discriminated with regard to these emotions with values of 0.62 and -0.44 for patients with pd and for controls , respectively . the incidences of sensations such as discomfort , agitation , rejection , disorientation , dependence and insecurity were not significantly different between the groups , indicating that both sets of participants developed similar feelings toward their mps . this finding illustrates an interaction between people and new technology in which the latter promotes alterations in habits , behaviors and emotions . as such , these interactions should be studied further . as for the significant between - group differences in self - esteem and loneliness , we observed significant differences between the two groups with regard to the incidence of rejection , self - esteem , loneliness and insecurity ( table 4 ) . all participants reported feeling an emotional emptiness when they called their friends more than when they received calls or when they did not frequently receive calls . thus , we consider that this new research on the use of the mp is important . our study found that patients with pds felt significantly more anxious and depressed with regard to their mp use than did the healthy controls . these symptoms tended to appear in patients with pd when they did not have an mp available or were unable to make a call . the patients also reported greater feelings of rejection , loneliness , insecurity and lower self - esteem when they received few calls on their mps compared to the feelings experienced by the control group . verifying these symptoms in patients with pd may be useful for psychological interventions and for examining behavioral changes during treatment . another interesting finding was that healthy people received and placed more calls with their mps than patients with pd with agoraphobia ( table 3 ) . according to rang , flight or evasion behaviors can limit the mobility and autonomy of patients with pd and agoraphobia . in this study , patients with agoraphobia frequently reported a fear of feeling ill in public and not having an mp to call for immediate assistance . unlike patients with general anxiety disorder ( gad ) , who complain of constant worry and tension , patients with pd present physical symptoms of panic ( i.e. , panic attacks ) including problems related to the pulmonary , cardiovascular and gastrointestinal systems as well as to their nerves . we observed that patients with gad and those with pd reported increased anxiety , tension and constant worry when they did not have their mp . we considered their answer to the question regarding their feelings as they describe it ( table 3 ) . that is , their own description of the subjective suffering could be the best way for us to understand their feelings . some of them could understand the differences between a panic attack , chronic worry with somatic symptoms ( anxiety ) , and the specific fear of a specific situation ( fear ) such as being without an mp , but others could not understand the differences . the subjects were , therefore , free to question the research team about their doubts while completing the questionnaire . approximately 50 % to 70 % of the patients with pd have hypochondria , whereas only 13 % to 17 % of patients with hypochondria have pd . hypochondria and pd are comorbid when health concerns are not limited to panic attack symptoms . conversely , dependence associated with nomophobia refers to a disproportionate emotional reaction to the function that the technology serves . for example , just as people can be alcoholics or drug addicts , they can be mp addicts . specifically , addicts are no longer able to recognize the negative repercussions of their consumption on their psychological health , family , social life and career . furthermore , addicts often fail in their efforts to suspend or limit their substance consumption . in our observation of pd patients with agoraphobia , there is a difference between seeking social phone contact ( positive reinforcement ) vs. contacting people by phone as a way to avoid panic or its consequences ( negative reinforcement ) . compulsion and safety - seeking behavior may be a more appropriate model for the use of the mp by pd patients than is an addiction model . in this study ,68 % of all participants reported some level of dependence on their mps , which called our attention to numerous aspects that should be investigated and possibly treated , including anxiety disorders . mp dependence may reveal the presence of a primary disorder , such as dependent personality disorder . this condition is characterized by a fear of abandonment , the self - perception of being weak and incompetent , and difficulty with meeting the demands of daily life . in these patients , dependence on an mp may reveal the need for an agent to facilitate social relationships and communication to increase self - esteem . as patients with anxious personality disorder may judge whether they are loved and accepted based on the number of calls they receive per day , they may experience additional rejection when they receive fewer calls than other people . patients with pd with agoraphobia , which is associated with anxiety and recurrent panic attacks , exhibit mp dependence . people with pd fear situations such as having a heart attack , becoming ill in public , or straying far from home . people with pd and mp dependence may attribute their dependence to their need to contact emergency services or people they trust , such as doctors , psychologists or members of their family . the relationship between rejection sensitivity and a typical depression is highly co - morbid with panic . people with atypical depression or pd may experience difficulties in maintaining relationships , especially due to the fear of rejection . however , in addition to looking at the diagnostic criteria for both cases , we can observe that the feeling of rejection in atypical depression relates more with psychological structuring ( insecurity , shyness and low self - esteem ) than the feeling of rejection in pd where the individual feels rejected by failing to fully respond to social events . nomophobia is also related to the fear of making or receiving a phone call ( literally , telephone fear ) . adult separation anxiety is distinct from its childhood form by its intensity , seriousness , persistence beyond infancy and association with a significant disturbance in social functioning . in these patients , mp dependence may be related to separation anxiety and the need to be accompanied to feel secure . the current study demonstrated that 44 % of patients with pd felt accompanied when they possessed an mp and that 46.0 % revealed that they would not feel the same freedom of movement without an mp . these findings illustrate that new technologies alter the habits , behaviors and emotions of the users . to maintain an accurate profile of modern humans as their habits and behaviors change with technological advancements , additional studies that observe people s physiological and emotional reactions to innovation are necessary . behavioral changes , whether positive or negative , require constant observation to prevent possible disorders . furthermore , human interactions with technology should be monitored . this study has some limitations , including its small sample size and its lack of background literature . additionally , the fact that the primary instrument s psychometric parameters were not evaluated for its target population presents a limitation . one implication of this limitation is that the instrument can not be portrayed as a measure of the construct called nomophobia . however , the individual items can be used , as was performed in this study , to indicate participant responses to specific questions . we suggest that additional studies develop specific instruments that have good validity and reliability to assess nomophobia parameters . we did not investigate whether participants behaviors matched the emotions that they reported related to mp use / deprivation , whether the behaviors were specific to the mp or whether the behaviors are generalized . despite having excluded people with psychiatric disorders from the control group , we did not check for any health problems that may have interfered with their relationship to their mp . we found that mps are an integral part of the popular culture and that the majority of people possess or aspire to possess an mp . we verified that this desire is due to the mps increased convenience , comfort and security . although several studies state that these resources have benefits , their use can lead to abuse and to a lack of control , which severely affects the daily lives of users . thus , we reaffirm the importance of a new study regarding the use of the mp . our study is a novel and creative contribution to the interaction of modern technology with common psychopathology . at the same timethe mobile phone may be working as a \" phobic partner \" for some patients ; however , their behavior and specific characteristic make the mp unique , and consequently , the use of the mp deserves a psychopathological description . the questions of our study are not absolutely specific to the relationship between the use of the mp and pd . further trials and improvements to our questionnaire may promote the quality of future psychopathological studies . the studies of the relationships between individuals and new technologies are relevant because the new technologies produce behavioral changes as well as feelings and symptoms that should be studied and monitored continuously in a modern society . the relationship of the mp in patients with pd shows that the behavior of the patient is proportional to the level of insecurity and fear . patients with pd report that when they have the mp in their hands , they feel as if they are not alone , that is , they have a feeling of being accompanied . we do not intend to manage the use of the mp use in treatment or wean patients from the apparatus . as we have observed in this study , the mp brought comfort and safety to both groups . with respect to pd , the medical and psychological treatments should be directed to and should focus on the main symptoms . the extent to which the patient progresses in treatment , therefore , will be evidenced by his / her ability to abandon the pathological dependence on the mp and the reduction in other behaviors related to pd . we thank the national council for technological and scientific development ( cnpq ) and the national institute for translational medicine ( inct - tm ) for supporting this research .\noutput:\n" }, { "from": "agent", "value": "panic disorder refers to the frequent and recurring acute attacks of anxiety . objective : this study describes the routine use of mobiles phones ( mps ) and investigates the appearance of possible emotional alterations or symptoms related to their use in patients with panic disorder ( pd ) . background : we compared patients with pd and agoraphobia being treated at the panic and respiration laboratory of the institute of psychiatry , federal university of rio de janeiro , brazil , to a control group of healthy volunteers . methods : an mp - use questionnaire was administered to a consecutive sample of 50 patients and 70 controls . results : people with pd showed significant increases in anxiety , tachycardia , respiratory alterations , trembling , perspiration , panic , fear and depression related to the lack of an mp compared to the control group . conclusions : both groups exhibited dependence on and were comforted by having an mp ; however , people with pd and agoraphobia showed significantly more emotional alterations as well as intense physical and psychological symptoms when they were apart from or unable to use an mp compared to healthy volunteers ." } ]

[ { "from": "human", "value": "***task***\nthe task is to summarize an input biomedical literature in six sentences\n\n***input***\nthe input is a biomedical literature\n\n***output***\nthe output is the summary of an input biomedical literature in six sentences\n\n***documentation***\n\n***examples***\n\ninput: . the cyst may either be congenital ( developmental ) or acquired . to a large extent , the differential diagnosis depends on its location in the mediastinum ( anterior , middle or posterior compartments ) . the cysts of non - infective etiology may be complicated by secondary infection and certain primary infectious conditions such as hydatid disease can also present with mediastinal cysts . a 14 - year old boy presented with a history of dry cough and progressively increasing breathlessness for a duration of three months . this was associated with dysphagia and stridulous noises on lying down ( both supine and prone ) . a chest radiograph was performed , which revealed a widening of the superior mediastinum [ figure 1 ] . computed tomography ( ct ) of the chest revealed the presence of a multiloculated cystic mass located posterior to the trachea , starting at the level of the thoracic inlet and extending to the level of the carina [ figure 2 ] . laboratory investigations revealed anemia ( hemoglobin 10.2 g / dl ) , with normal leucocytes ( 5,800 / l ) and platelet counts ( 232,000 / l ) . he had deranged liver functions ( bilirubin 0.3 mg / dl , aspartate transaminase 54 u / l [ n , 0 - 35 ] , alanine transaminase 103u / l [ n , 0 - 35 ] , and alkaline phosphatase 212 u / l [ n , 0 - 130 ] ) . chest radiograph showing mediastinal widening in the superior part ( a and b ) computed tomography ( ct ) of the chest depicting the cystic lesion posterior to the trachea the following diagnoses were considered : ( a ) secondarily infected foregut duplication cyst , ( b ) bronchogenic cyst , ( c ) hydatid cyst , and ( d ) cystic schwannoma with secondary infection . however , it was deemed unlikely , as the patient did not have any fever or back pain , and the chest tomogram did not show any vertebral involvement . ultrasound - guided needle aspiration from the mass revealed well - defined epithelioid cell granulomas and multinucleated giant cells , with necrotic material in the background . the patient was started on antituberculosis treatment with rifampicin , isoniazid , pyrazinamide , and ethambutol in doses according to his weight . his symptoms improved and he became completely asymptomatic in a month . a ct chest repeated at three months showed complete disappearance of the mass [ figure 3 ] . ( a and b ) computed tomography ( ct ) of the chest showing complete resolution of the lesion after treatmentmediastinal involvement with tuberculosis usually occurs in the form of enlarged lymph nodes . on a contrast - enhanced ct , tuberculous mediastinal lymph nodes show a central hypodense area , which is suggestive of central necrosis . on an endobronchial ultrasound , this occurs either as a result of extensive necrosis in the conglomerate tuberculous lymph nodes or as a result of a direct extension from a cervical cold abscess . the location of tuberculous mediastinal abscess is usually in the anterior or middle mediastinum , secondary to extensive involvement of the lymph nodes . the appearance of a cystic lesion in the retrotracheal and paravertebral area without involvement of the spine is unusual . the index patient did not have back pain and there was no spinal involvement , as seen on the chest ct . we did not perform any specific imaging of the spine , as the diagnosis was already established and the clinical suspicion of spinal tuberculosis was low in view of lack of symptoms and no spinal involvement on ct . in conclusion , tuberculosis may present as a cystic lesion in the posterior mediastinum without any vertebral involvement . it may respond completely to anti - tuberculosis treatment without the need for surgical drainage .\noutput:\n" }, { "from": "agent", "value": "cystic lesions of the mediastinum may be congenital or acquired . the differential diagnosis depends on their location in the mediastinum . cysts in the posterior mediastinum are generally developmental cysts and are neurogenic or of foregut origin . we report the case of a 14 - year - old boy , who presented with dry cough and progressively increasing breathlessness , and was found to have a cystic lesion in the posterior mediastinum . fine needle aspiration from the cyst helped make a diagnosis of tuberculosis ." } ]