bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave reflection and central aortic pressure are increased in response to static and dynamic muscle contraction at comparable workloads
Authors: Edwards David G. , Mastin Corey R. , Kenefick Robert W.
Published: December 2007

We determined the effects of static and dynamic muscle contraction at equivalent workloads on central aortic pressure and wave reflection. At random, 14 healthy men and women (23 ± 5 yr of age) performed a static handgrip forearm contraction [90 s at 30% of maximal voluntary contraction (MVC)], dynamic handgrip contractions (1 contraction/s for 180 s at 30% MVC), and a control trial. During static and dynamic trials, tension-time index was controlled by holding peak tension constant. Measurements of brachial artery blood pressure and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) were conducted at baseline, during each trial, and during 1 min of postexercise ischemia (PEI). Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform. AI increased during both static and dynamic trials (static, 5.2 ± 3.1 to 11.8 ± 3.4%; dynamic, 5.8 ± 3.0 to 13.3 ± 3.4%; P < 0.05) and further increased during PEI (static, 18.5 ± 3.1%; dynamic, 18.6 ± 2.9%; P < 0.05). Peripheral and central systolic and diastolic pressures increased ( P < 0.05) during both static and dynamic trials and remained elevated during PEI. AI and pressure responses did not differ between static and dynamic trials. Peripheral and central pressures increased similarly during static and dynamic contraction; however, the rise in central systolic pressure during both conditions was augmented by increased wave reflection. The present data suggest that wave reflection is an important determinant of the central blood pressure response during forearm muscle contractions.
Exercise training enhances baroreflex sensitivity by an angiotensin II-dependent mechanism in chronic heart failure
Authors: Mousa Tarek M. , Liu Dongmei , Cornish Kurtis G. , Zucker Irving H.
Published: December 2007

Exercise training (EX) has become an important modality capable of enhancing the quality of life and survival of patients with chronic heart failure (CHF). Although 4 wk of EX in animals with CHF evoked a reduction in renal sympathetic nerve activity and ANG II plasma levels and an enhancement in baroreflex sensitivity at rest (Liu JL, Irvine S, Reid IA, Patel KP, Zucker IH, Circulation 102: 1854–1862, 2000; Liu JL, Kulakofsky J, Zucker IH, J Appl Physiol 92: 2403–2408, 2002), it is unclear whether these phenomena are causally related. CHF was induced in rabbits by ventricular pacing (360–380 beats/min) for 3 wk. CHF rabbits were EX for 4 wk at 15–18 m/min, 6 days/wk, 30–40 min/day. Three groups of rabbits were studied: CHF (with no EX), CHF-EX, and CHF-EX + ANG II infusion [in which ANG II levels were kept at or near levels observed in CHF (non-EX) rabbits by subcutaneous osmotic minipump infusion]. EX prevented the increase in plasma ANG II levels shown in CHF rabbits. CHF and CHF-EX + ANG II infusion rabbits had significantly depressed baroreflex sensitivity slopes ( P < 0.01 for sodium nitroprusside and P < 0.001 for phenylephrine) and higher baseline renal sympathetic nerve activities than CHF-EX animals. EX downregulated mRNA and protein expression of ANG II type 1 receptors in the rostral ventrolateral medulla in CHF rabbits. This was prevented by ANG II infusion. These data are consistent with the view that the reduction in sympathetic nerve activity and the improvement in baroreflex function in CHF after EX are due to the concomitant reduction in ANG II and angiotensin receptors in the central nervous system.
Individualized performance prediction of sleep-deprived individuals with the two-process model
Authors: Rajaraman Srinivasan , Gribok Andrei V. , Wesensten Nancy J. , Balkin Thomas J. , Reifman Jaques
Published: December 2007

We present a new method for developing individualized biomathematical models that predict performance impairment for individuals restricted to total sleep loss. The underlying formulation is based on the two-process model of sleep regulation, which has been extensively used to develop group-average models. However, in the proposed method, the parameters of the two-process model are systematically adjusted to account for an individual's uncertain initial state and unknown trait characteristics, resulting in individual-specific performance prediction models. The method establishes the initial estimates of the model parameters using a set of past performance observations, after which the parameters are adjusted as each new observation becomes available. Moreover, by transforming the nonlinear optimization problem of finding the best estimates of the two-process model parameters into a set of linear optimization problems, the proposed method yields unique parameter estimates. Two distinct data sets are used to evaluate the proposed method. Results of simulated data (with superimposed noise) show that the model parameters asymptotically converge to their true values and the model prediction accuracy improves as the number of performance observations increases and the amount of noise in the data decreases. Results of a laboratory study (82 h of total sleep loss), for three sleep-loss phenotypes, suggest that individualized models are consistently more accurate than group-average models, yielding as much as a threefold reduction in prediction errors. In addition, we show that the two-process model of sleep regulation is capable of representing performance data only when the proposed individualized model is used.
Mechanics of the canine diaphragm in ascites: a CT study
Authors: Leduc Dimitri , Cappello Matteo , Gevenois Pierre Alain , De Troyer André
Published: December 2007

Ascites causes an increase in the elastance of the abdomen and impairs the lung-expanding action of the diaphragm, but its overall effects on the pressure-generating ability of the muscle remain unclear. In the present study, radiopaque markers were attached to muscle bundles in the midcostal region of the diaphragm in five dogs, and the three-dimensional locations of the markers during relaxation and during phrenic nerve stimulation in the presence of increasing amounts of ascites were determined using a computed tomographic scanner. From these data, accurate measurements of muscle length and quantitative estimates of diaphragm curvature were obtained, and the changes in transdiaphragmatic pressure (Pdi) were analyzed as functions of muscle length and curvature. With increasing ascites, the resting length of the diaphragm increased progressively. In addition, the amount of muscle shortening during phrenic nerve stimulation decreased gradually. When ascites was 100 ml/kg body wt, therefore, the muscle during contraction was longer, leading to a 20–25% increase in Pdi. As ascites increased further to 200 ml/kg, however, muscle length during contraction continued to increase, but Pdi did not. This absence of additional increase in Pdi was well explained by the increase in the diameter of the ring of insertion of the diaphragm to the rib cage and the concomitant increase in the radius of diaphragm curvature. These observations indicate that the pressure-generating ability of the diaphragm is determined not only by muscle length as conventionally thought but also by muscle shape.
Long-term cardiovascular effects of neonatal dexamethasone treatment: hemodynamic follow-up by left ventricular pressure-volume loops in rats
Authors: Bal Miriam P. , de Vries Willem B. , van Oosterhout Matthijs F. M. , Baan Jan , van der Wall Ernst E. , van Bel Frank , Steendijk Paul
Published: December 2007

Dexamethasone is clinically applied in preterm infants to treat or prevent chronic lung disease. However, concern has emerged about adverse side effects. The cardiovascular short-term side effects of neonatal dexamethasone treatment are well documented, but long-term consequences are unknown. Previous studies showed suppressed mitosis during dexamethasone treatment, leading to reduced ventricular weight, depressed systolic function, and compensatory dilatation in prepubertal rats. In addition, recent data indicated a reduced life expectancy. Therefore, we investigated the long-term effects of neonatal dexamethasone treatment on cardiovascular function. Neonatal rats were treated with dexamethasone or received saline. Cardiac function was determined in 8-, 50-, and 80-wk-old animals, representing young adult, middle-aged, and elderly stages. A pressure-conductance catheter was introduced into the left ventricle to measure pressure-volume loops. Subsequently, the hearts were collected for histological examination. Our results showed reduced ventricular and body weights in dexamethasone-treated rats at 8 and 80 wk, but not at 50 wk. Cardiac output and diastolic function were unchanged, but systolic function was depressed at 50 and 80 wk, evidenced by reduced ejection fractions and rightward shifts of the end-systolic pressure-volume relationships. We concluded that previously demonstrated early adverse effects of neonatal dexamethasone treatment are transient but that reduced ventricular weight and systolic dysfunction become manifest again in elderly rats. Presumably, cellular hypertrophy initially compensates for the dexamethasone treatment-induced lower number of cardiomyocytes, but this mechanism falls short at a later stage, leading to systolic dysfunction. If applicable to humans, cardiac screening of a relatively large patient group to enable secondary prevention may be indicated.
Prostaglandin synthesis can be inhibited locally by infusion of NSAIDS through microdialysis catheters in human skeletal muscle
Authors: Mikkelsen Ulla Ramer , Helmark Ida Carøe , Kjær Michael , Langberg Henning
Published: December 2007

Prostaglandins are known to be involved in the regulation of local blood flow within human skeletal muscles during exercise, and the concentration of prostaglandins increases locally and systemically in response to exercise. The systemic release of prostaglandins can be inhibited by oral intake of nonsteroidal anti-inflammatory drugs (NSAIDs). However, to study the local role of prostaglandins, the formation of prostaglandins within the tissue must be controlled. Microdialysis enables determination of local concentrations of water-soluble substances within the tissue. In the present study, the microdialysis method was used to infuse NSAIDs locally into human skeletal muscles producing a local block of prostaglandin formation. In addition, the graded blockade at various distances from the infusion site within the muscle during rest, exercise and recovery was determined. Microdialysis was performed in thigh muscles (vastus lateralis muscle) in six healthy men. One of the microdialysis catheters was used to block prostaglandin synthesis by infusion of the NSAID indomethacin. Additional catheters were placed 1 and 4 cm away from the infusion and in the contralateral leg (working control). Following 2 h of rest, the subjects performed 200 maximal eccentric contractions with each leg followed by 3 h of rest. The study revealed that infusion of NSAID reduced local prostaglandin E2 concentration by ∼30–50% (4 cm away from the infusion) and 85% (1 cm away from the infusion) compared with the contralateral (unblocked) thigh muscle. In conclusion, the present study shows that infusion of NSAIDs into human muscle via microdialysis catheters results in a graded blockade of prostaglandin synthesis.
Exercise-induced attenuation of obesity, hyperinsulinemia, and skeletal muscle lipid peroxidation in the OLETF rat
Authors: Morris R. Tyler , Laye Matthew J. , Lees Simon J. , Rector R. Scott , Thyfault John P. , Booth Frank W.
Published: December 2007

The Otsuka Long-Evans Tokushima fatty (OLETF) rat is a model of hyperphagic obesity in which the animals retain the desire to run voluntarily. Running wheels were provided for 4-wk-old OLETF rats for 16 wk before they were killed 5 h (WL5), 53 h (WL53), or 173 h (WL173) after the wheels were locked. Sedentary (SED) OLETF rats that were not given access to running wheels served as age-matched cohorts. Epididymal fat pad mass, adipocyte volume, and adipocyte number were 58%, 39%, and 47% less, respectively, in WL5 than SED rats. Contrary to cessation of daily running in Fischer 344 × Brown Norway rats, epididymal fat did not increase during the first 173 h of running cessation in the OLETF runners. Serum insulin and glucose levels were 77% and 29% less, respectively, in WL5 than SED rats. Oil red O staining for intramyocellular lipid accumulation was not statistically different among groups. However, lipid peroxidation levels, as determined by total trans-4-hydroxy-2-nonenal (4-HNE) and 4-HNE normalized to oil red O, was higher in epitrochlearis muscles of SED than WL5, WL53, and WL173 rats. mRNA levels of glutathione S-transferase-α type 4, an enzyme involved in cellular defense against electrophilic compounds such as 4-HNE, were higher in epitrochlearis muscle of WL53 than WL173 and SED rats. In contrast, 4-HNE levels in omental fat were unaltered. Epitrochlearis muscle palmitate oxidation and relative transcript levels for peroxisome proliferator-activated receptor-δ and peroxisome proliferator-activated receptor-γ coactivator type 1 were surprisingly not different between runners and SED rats. In summary, voluntary running was associated with lower levels of lipid peroxidation in skeletal muscle without significant changes in intramyocellular lipids or mitochondrial markers in OLETF rats at 20 wk of age. Therefore, even in a genetic animal model of extreme overeating, daily physical activity promotes improved health of skeletal muscle.
Femoral-gluteal subcutaneous and intermuscular adipose tissues have independent and opposing relationships with CVD risk
Authors: Yim Jung-Eun , Heshka Stanley , Albu Jeanine B. , Heymsfield Steven , Gallagher Dympna
Published: December 2007

Femoral-gluteal adipose tissue (AT) may be cardioprotective through fatty acids uptake. Femoral-gluteal AT has previously been defined as leg fat measured by dual energy x-ray absorptiometry (DXA); however, subcutaneous adipose tissue (SAT) and intermuscular adipose tissue (IMAT) are inseparable using DXA. This study investigated the independent relationships between femoral-gluteal SAT, femoral-gluteal IMAT, and cardiovascular disease (CVD) risk factors [fasting serum measures of glucose, total cholesterol (TC), high density lipoprotein cholesterol (HDLC), triglycerides (TG) and insulin] and whether race differences exist in femoral-gluteal AT distribution. Adult Caucasians (56 men and 104 women), African-Americans (37 men and 76 women), and Asians (11 men and 35 women) had total AT (TAT) including femoral-gluteal AT (upper leg SAT and IMAT) and visceral AT (VAT) by magnetic resonance imaging (MRI). General linear models identified the independent effects of femoral-gluteal SAT and femoral-gluteal IMAT on each risk factor after covarying for TAT, VAT, age, race, sex, and two-way interactions. Femoral-gluteal IMAT and glucose ( P < 0.05) were positively associated independent of VAT. There were also significant inverse associations between femoral-gluteal SAT and insulin ( P < 0.01) and TG ( P < 0.05), although the addition of VAT rendered these effects nonsignificant, possibly due to collinearity. Asian women had less femoral-gluteal SAT and greater VAT than Caucasians and African-Americans ( P < 0.05) and Asian and African-American men had greater femoral-gluteal IMAT than Caucasians, adjusted for age and TAT ( P < 0.05 for both). Femoral-gluteal SAT and femoral-gluteal IMAT distribution varies by sex and race, and these two components have independent and opposing relationships with CVD risk factors.
Influence of tongue muscle contraction and dynamic airway pressure on velopharyngeal volume in the rat
Authors: Fregosi Ralph F.
Published: December 2007

The mammalian pharynx is a collapsible tube that narrows during inspiration as transmural pressure becomes negative. The velopharynx (VP), which lies posterior to the soft palate, is considered to be one of the most collapsible pharyngeal regions. I tested the hypothesis that negative transmural pressure would narrow the VP, and that electrical stimulation of extrinsic tongue muscles would reverse this effect. Pressure (−6, −3, 3, and 6 cmH2O) was applied to the isolated pharyngeal airway of anesthetized rats that were positioned in a 4.7-T MRI scanner. The volume of eight axial slices encompassing the length of the VP was computed at each level of pressure, with and without bilateral hypoglossal nerve stimulation (0.1-ms pulse, one-third maximum force, 80 Hz). Negative pressure narrowed the VP, and either whole hypoglossal nerve stimulation (coactivation of protrudor and retractor muscles) or medial nerve branch stimulation (independent activation of tongue protrudor muscles) reversed this effect, with the greatest impact in the caudal one-third of the VP. The dilating effects of medial branch stimulation were slightly larger than whole nerve stimulation. Positive pressure dilated the VP, but tongue muscle contraction did not cause further dilation under these conditions. I conclude that the narrowest and most collapsible segment of the rat pharynx is in the caudal VP, posterior to the tip of the soft palate. Either coactivation of protrudor and retractor muscles or independent contraction of protrudor muscles caused dilation of this region, but the latter was slightly more effective.
Thermoregulation during exercise in the heat in children: old concepts revisited
Authors: Rowland Thomas
Published: December 2007

Children possess certain physiological and anatomic characteristics that have traditionally been considered to impair thermoregulatory responses to exercise in the heat: low exercise economy, high ratio of body surface area to mass, diminished sweating capacity, and less cardiac output at the same work load compared with adults. Consequently, children have been regarded as an at-risk group for not only decrements of physical performance but also heat injury during physical activities performed in conditions of high ambient temperature. Recent investigations that have directly compared thermoregulatory responses to exercise in the heat in children and adults have challenged these traditional concepts. Such studies have failed to indicate group differences in heat dispersal when adult-child comparisons are appropriately considered in respect to relative exercise intensity. These findings imply that no maturational differences exist in thermal balance or endurance performance during exercise in the heat, nor that child athletes are more vulnerable to heat injury.
Quality Control on Endoscopic Maintenance and Repair Services: Safety Considerations for the Patient
Authors: Rey Jean-François
Published: December 2007

Quality control and maintenance services are 2 important points when we organize an endoscopic unit. From the medical side, we have always expected to purchase the most advanced equipment and obtained the best-repaired service. From the hospital administrators’ point of view the global costs of endoscopic equipment is the most important criterion. These 2 goals should be compatible by a close relationship between medical doctors and hospital administrators. The quality of maintenance and the reliability of services are important points considering quality control and safety for our patients. Endoscope malfunctions and inadequate repair services could be a threat for our patients. In this case, legal responsibility could rely on hospital and medical doctors if services and maintenance have not been carefully planned.
Why There Is a Need of an Ethics Committee in Scientific Medical Societies
Authors: Montori A. , Onorato M.
Published: December 2007

Scientific associations involved in clinical activities are responsible to their members and to the medical community when using new drugs or technologies in clinical practice. Any new procedure or clinical use of new drugs represents a form of research and should adhere to guidelines defined by an ethics committee. It is therefore important that all medical scientific societies should establish an ethics committee. The ethics committee should be in direct contact with the scientific or research committee of the society to evaluate if a clinical trial is useful and not dangerous for patients. A group of expert members of this committee should advise the best method to avoid harm or discomfort to the patient. This gives the best guarantee and can evaluate the real progress of such a new procedure for the benefit of the patient.
Psychological Profile of Obese Patients
Authors: Lykouras Lefteris
Published: December 2007

Nowadays obesity is recognized to be one of the greatest public health problems worldwide. There is no indication that the huge increase in obesity seen the last decades is declining. The examination of psychological aspects of persons with morbid obesity is essential. Identification of the psychological factors associated with weight loss expands our knowledge about behaviors which are crucial in order to avoid failures in treatment. Most information on this is obtained preoperatively. Although there is no single personality type characteristic of the morbidly obese, they differ from the general population as their self-esteem and impulse control is lower. They have passive dependent and passive aggressive personality traits, as well as a trend for somatization and problem denial. Their thinking is usually dichotomous and catastrophic. Obese patients also show low cooperativeness and fail to see the self as autonomous and integrated. In the morbidly obese before undergoing surgical treatment, unusual prevalence of psychopathology, namely depression and anxiety disorders, is observed. They are subject to prejudice and discrimination and should be treated with concern to help alleviate their feelings of rejection and guilt. Information on the psychological profile of obese persons is limited. Future studies are warranted, since there is a pressured need for these people to built cognitive skills and control their body weight.
Intragastric Balloon Treatment for Obesity: What Does It Really Offer?
Authors: Mathus-Vliegen Elisabeth M.H.
Published: December 2007

Obesity is a chronic metabolic disorder with considerable health risks, which can be approved by a sustained modest weight loss. This can be achieved by medical treatment through behavioral therapy, diet, exercise and pharmacotherapy. Surgery is often needed for the severely obese. Intragastric balloon treatment stands in between, being more drastic than medical treatment but less invasive than surgery. In the light of the high premature deflation rate and the high incidence of gastric ulcers, a safer balloon had to be awaited, constructed according to predefined criteria. This new balloon (BioEnterics® Intragastric Balloon™) promoted a weight loss of 5–9 BMI units in 6 months with an impressive improvement of obesity-associated comorbidities. A weight regain of 25–40% has to be considered in a 1-year balloon-free follow-up period. A failure rate of 15% was observed in studies that defined a successful weight loss. With respect to safety, there was no mortality. Gastrointestinal complications, mainly consisting of esophagitis, were present in 5.5%. Intolerance of the balloon resulted in its removal in 7%. Balloons deflated in 8% with an uneventful outcome in all except 5 patients, who had to be operated. Balloon treatment is a valuable method, but nonresponse, intolerance and weight regain have to be taken into account.
Complications of ERCP: Ethical Obligations and Legal Consequences
Authors: Rácz István , Rejchrt Stanislav , Hassan Majid
Published: December 2007

Endoscopic retrograde cholangiopancreatography (ERCP) is a skill and technique demanding high-risk procedure with an overall complication rate of about 5–10%. Pancreatitis remains the most common complication of ERCP, however, bleeding after sphincterotomies, infections and cardiopulmonary complications as well as perforations may also occur. Patient- and procedure-related risk factors of ERCP complications are mainly predictable so that ERCP often can be avoided and substituted for alternative imaging techniques, especially in high-risk patients. Written consent should be obtained for any ERCP to provide documentary evidence that explanation of the proposed procedure and endoscopic treatment was given and that consent was sought and obtained. The investigating doctor remains responsible for ensuring sufficient time for the patient’s questions and to make informed decision before the start of any procedure. The most common legal consequence of an ERCP complication is a civil negligence claim for compensation, however, a clinician may in rare cases be faced with criminal proceedings where there is evidence of gross negligence. Analysis of claims against gastroenterologists suggests the conclusion that ERCP should be done for good indications, by trained endoscopists with standard techniques, with good, documented, patient-informed consent and communication before and after the procedure.
Breaking Bad News
Authors: Schoefl Rainer
Published: December 2007

Breaking bad news has been ignored in the past and still depends largely on culture and social state. We experience now a strong trend towards full information in modern societies. The article describes the typical stages patients go through when dealing with bad news. Recommendations how to break bad news stress the importance of privacy and enough time, the necessity to learn how much knowledge is pre-existing, to wait until the patient signalizes readiness, to give the information in small, understandable portions, to recognize and encourage emotions and to sum up and schedule further meetings. A special appraisal of the situation in gastrointestinal endoscopy is given.
Ethics Related to Liver Biopsies and Antiviral Therapies in Chronic Viral Hepatitis
Authors: Papatheodoridis George V.
Published: December 2007

Ethics related to liver biopsies in patients with chronic viral hepatitis mainly include issues on the indications, potential risks and benefits and validity of available alternative options. Liver biopsy is the gold standard for the overall evaluation of liver lesions, but its indications are decreasing. It is not usually required for the correct etiological diagnosis but mostly for the appropriate classification in specific settings. It certainly estimates the severity of liver injury, which influences the prognosis and perhaps therapeutic decisions. It is generally a simple and safe but invasive procedure, which carries a small risk for complications, requires the patient’s admission for 12–24 h and may have sampling errors. New, rather accurate, noninvasive tests have been developed and their use may increase in the future, perhaps not for the initial evaluation but mostly for the long-term follow-up of such patients. Therapeutic options for chronic viral hepatitis have substantially improved over the last decade, but there are still several unsettled issues creating ethical dilemmas. Treating physicians should ideally have knowledge and personal experience on several aspects of the management of patients with chronic viral hepatitis, who should be adequately informed and participate in the decisions for liver biopsy and/or therapeutic intervention.
Dramatic Decline of Acute Appendicitis in Greece over 30 Years: Index of Improvement of Socioeconomic Conditions or Diagnostic Aids?
Authors: Papadopoulos A.A. , Polymeros D. , Kateri M. , Tzathas C. , Koutras M. , Ladas S.D.
Published: December 2007

Background and Aims: There are several reports showing a continuing fall in the incidence of acute appendicitis in the western countries. Our aim was to study the trend of the incidence of acute appendicitis in the Greek population over 30 years. Methods: We analyzed the data referring to the years 1970–1999 on the incidence and mortality of acute appendicitis for the entire Greek population. Data were retrieved from the Annual Bulletin for the Social Welfare and Health Statistics of the National Statistics Service of Greece. In this database, acute appendicitis was a hospital discharge diagnosis. Results: Over the study period, there was a 75% decrease of the age-standardized incidence of acute appendicitis from 652/100,000 to 164/100,000. The median female-to-male ratio of hospitalized patients for appendicitis of the study period (1970–1999) fell progressively from 1.27 in the year 1970 to 0.93 in the year 1999. The case fatality rates remained constant, ranging below 0.09 deaths per 100 appendicitis cases. Conclusion: There is a significant decline of the incidence of acute appendicitis in the Greek population over the years 1970–1999. This time trend is probably related to the improvement of the socioeconomic conditions over the same period and not to the introduction of new diagnostic aids.
DNA degradation during maturation of erythrocytes – molecular cytogenetic characterization of Howell-Jolly bodies
Authors: Felka T. , Lemke J. , Lemke C. , Michel S. , Liehr T. , Claussen U.
Published: December 2007

Howell-Jolly bodies (HJBs) are small DNA-containing inclusions of erythrocytes and are often present after splenectomy. The genetic composition of HJBs is unknown at present. We isolated individual erythrocytes that had inclusion bodies from five splenectomized patients and performed DNA amplification using degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) with subsequent reverse painting on normal male metaphase spreads. We also measured the sizes of HJBs in erythrocytes from a splenectomized patient using an inverted microscope. Two-dimensional positions of HJBs were projected onto a virtual erythrocyte. The average size of HJBs was 0.73 ± 0.17 µm (range 0.4–1.1 µm). Inside the erythrocyte the HJBs were found to be equally distributed. Small HJBs contained DNA from one or two centromeres and larger HJBs contained DNA from up to eight different centromeres. Centromeric DNA from chromosomes 1/5, 7, 8, and 18 was most frequently observed. Signals from the centromeric regions of chromosomes 3, 4, 9, and 10 were not observed. Signals from euchromatic regions were detected in a few cases. We hypothesize that in addition to enucleation and nucleus fragmentation DNA degradation during maturation of erythrocytes preferentially eliminates euchromatic DNA. Similarities between these processes and those described for embryonic stem cells suggest that most stem cells are able to degrade DNA in a genetically controlled manner.
The molecular basis of the folate-sensitive fragile site FRA11A at 11q13
Authors: Debacker K. , Winnepenninckx B. , Longman C. , Colgan J. , Tolmie J. , Murray R. , van Luijk R. , Scheers S. , FitzPatrick D. , Kooy F.
Published: December 2007

We report on the molecular basis of the rare, folate-sensitive fragile site FRA11A in chromosome band 11q13 in a family with cytogenetic expression. Five individuals express the fragile site and one was mentally retarded. Expansion of a polymorphic CGG-repeat located at the 5′ end of the C11orf80 gene causes FRA11A. The CGG-repeat elongation coincides with hypermethylation of the adjacent CpG island and subsequent transcriptional silencing of the C11orf80 gene. This gene has no homology with known genes. A relationship between cytogenetic expression of the fragile site and the mental handicap seems unlikely, as FRA11A was found in a mentally retarded patient as well as in phenotypically normal carriers from the same family. However, incomplete penetrance cannot be entirely excluded.
Molecular studies of segmental aneusomy: FISHing for the atypical cry in del(5)(p15.3)
Authors: Hodge J.C. , Lawson-Yuen A. , Stoler J.M. , Ligon A.H.
Published: December 2007

We report a newborn male with multiple congenital anomalies including growth retardation, hypotonia, dysmorphic facies, widely-spaced nipples, micropenis, cryptorchidism, optic nerve hypoplasia, heart disease, and a striking, high-pitched cry. Chromosome analysis revealed de novo partial trisomy 11q due to a der(5)t(5;11)(p15.3;q22). Fluorescence in situ hybridization (FISH) showed loss of the 5p telomere signal on the der(5) chromosome, indicating the infant has partial monosomy 5p in addition to partial trisomy 11q. Among cases involving trisomy 11q, an unusual cry has only been documented in the presence of a der(5)t(5p;11q). This apparent dependence of the abnormal cry on monosomy 5p suggested the same genetic mechanism that occurs in Cri du chat syndrome (CDCS) may be responsible for the atypical cry in der(5)t(5p;11q) individuals. Neither a commercial CDCS probe (LSI D5S23, D5S721) nor a series of BAC clones encompassing distal regions implicated in the CDCS-associated cat-cry were deleted in our patient. These results suggest a second cry-modifying locus maps telomeric to BAC RP11-94J21 in band 5p15.33. This locus may not only cause the abnormal cry in individuals with a der(5)t(5p;11q) but could also contribute to the phenotypic variability and discordant mapping studies observed for CDCS.
Discontinuities and unsynapsed regions in meiotic chromosomes have a trans effect on meiotic recombination of some chromosomes in human males
Authors: Sun F. , Oliver-Bonet M. , Liehr T. , Starke H. , Ko E. , Rademaker A. , Martin R.H.
Published: December 2007

During meiosis, homologous chromosome pairing and synapsis are essential for subsequent meiotic recombination (crossing-over). Discontinuous regions (gaps) and unsynapsed regions (splits) were most frequently observed in the heterochromatic regions of bivalent synaptonemal complex (SC) 9, and we have previously demonstrated that gaps and splits significantly altered the distribution of MLH1 recombination foci on SC 9. Here, immunofluorescence techniques (using antibodies against SC proteins and the crossover-associated MLH1 protein) were combined with a centromere-specific fluorescence in situ hybridization technique that allows identification of every individual chromosome. The effect of gaps/splits on meiotic recombination patterns in autosomes other than chromosome 9 during the pachytene stage of meiotic prophase was then examined in 6,026 bivalents from 262 pachytene cells from three human males. In 64 analyzed cells with a gapped SC 9, the frequency of MLH1 foci in SCs 5 and 10 and in SC arms 10q, 11p and 16q was decreased compared to 168 analyzed cells with a normally-synapsed SC 9 (controls). In 24 analyzed cells with splits in SC 9, there was a significant reduction in MLH1 focus frequency for SC 5q and the whole SC5 bivalent. The positioning of MLH1 foci on other SCs in cells with gapped/split SC 9 was not altered. These studies suggest that gaps and splits not only have a cis effect, but may also have a trans effect on meiotic recombination in humans.
PLAG1 activation in lipoblastoma coinciding with low-level amplification of a derivative chromosome 8 with a deletion del(8)(q13q21.2)
Authors: Röpke A. , Kalinski T. , Kluba U. , von Falkenhausen U. , Wieacker P.F. , Röpke M.
Published: December 2007

Lipoblastoma is a benign uncommon soft-tissue-tumor resembling fetal adipose tissue affecting mainly children under three years of age. In lipoblastoma, the typical cytogenetic changes are clonal rearrangements involving chromosomal region 8q11→q13. The oncogene PLAG1 (pleomorphic adenoma gene 1) is located within this chromosomal region on band 8q12. Recent reports have demonstrated that in lipoblastoma, the PLAG1 gene is activated by ‘promoter-swapping’. Herein, we demonstrate that in lipoblastoma, the PLAG1 gene may also be activated by low-level amplification. We report on a lipoblastoma with the karyotype 48∼50,XX,del(8)(q13q21.2),+del(8)(q13q21.2)×4[cp12]. Subsequent FISH analysis on uncultured tumor cells confirmed this result and demonstrated a low-level amplification of the chromosomal region 8pter→8q13 and 8q21.2→8qter. A partial monosomy was seen for the chromosomal region 8q13→8q21.2. No other gains or losses were observed by CGH analysis. RT-PCR analysis showed that the PLAG1 gene is activated in the tumor sample of the lipoblastoma analyzed, in contrast to normal fatty tissue without PLAG1 expression. In conclusion, our results demonstrate that low-level amplification is a further mechanism of PLAG1 activation in lipoblastomas.
Gene copy number analysis in malignant pleural mesothelioma using oligonucleotide array CGH
Authors: Lindholm P.M. , Salmenkivi K. , Vauhkonen H. , Nicholson A.G. , Anttila S. , Kinnula V.L. , Knuutila S.
Published: December 2007

Conventional cytogenetic analyses and comparative genomic hybridization have revealed a complex and even chaotic nature of chromosomal aberrations in pleural malignant mesothelioma (MM). We set out to describe the complex gene copy number changes and screen for novel genetic aberrations using a high-density oligonucleotide microarray platform for comparative genomic hybridization (aCGH) of a series of 26 well-characterized MM tumor samples. The number of copy number changes varied from zero to 40 per sample. Gene copy number losses predominated over gains, and the most frequent region of loss was 9p21.3 (17/26 cases), the locus of CDKN2A and CDKN2B, both known to be commonly lost in MM. The most recurrent minimal regions of losses were 1p31.1→ p13.2, 3p22.1→p14.2, 6q22.1, 9p21.3, 13cen→q14.12, 14q22.1→qter, and 22qcen→q12.3. Previously unreported gains included 9p13.3, 7p22.3→p22.2, 12q13.3, and 17q21.32→qter. The results suggest that gene copy number losses are a major mechanism of MM carcinogenesis and reveal a recurrent pattern of copy number changes in MM.
Double minutes (dmin) and homogeneously staining regions (hsr) in myeloid disorders: a new case suggesting that dmin form hsr in vivo
Authors: Reddy K.S.
Published: December 2007

We describe a case of an 87-year-old woman with myelodysplastic syndrome (MDS) in transformation. At presentation, the patient suffered from refractory anemia with excess of blasts (RAEB). The karyotype showed a clone with 3 to >20 double minutes (dmin) that were MYC-positive and, in addition, a cryptic deletion of MYC on one of the chromosome 8 homologs. The dmin varied both in size and in fluorescence intensity for the MYC probe following FISH. After six months, the disease had progressed to refractory anemia with excess of blasts in transformation (RAEBT). The corresponding karyotype showed a second cell line with two markers that appeared like rings and, again, a cryptic MYC deletion on one of the chromosome 8 homologs. The markers contained centromeres and amplified MYC sequences. The deletion of MYC on one of the chromosome 8 homologs and the variable sizes and intensities of the dmin supports an episome model for dmin formation. Chronologically, the MYC-positive dmin appeared first, followed by the appearance of MYC-positive marker chromosomes, suggesting that the dmin may have evolved to form homogeneously staining regions (hsr) in vivo.
Telomere dynamics and genome stability in the human pancreatic tumor cell line MIAPaCa-2
Authors: Škrobot Vidaček N. , Çukušić A. , Ferenac Kiš M. , Ivanković M. , Jevtov I. , Mrsić S. , Rubelj I.
Published: December 2007

Telomeres are specialized structures found at the ends of eukaryotic chromosomes serving as guardians of genome stability. In normal cells telomeres shorten with each cell division, but immortal cells undergoing multiple divisions constantly have to maintain telomere lengths above a critical level. This is accomplished either through expression of telomerase or the alternative recombination pathway (ALT). In the present study, we analyzed telomere dynamics of the telomerase positive human pancreatic tumor cell line MIAPaCa-2. The cells demonstrated genomic instability with a high frequency of chromosomal aberrations resulting in differences between individual karyotypes within the same cell population. The telomeres were short when compared with normal human fibroblasts, and about 39% of the chromosome ends did not have detectable telomere repeats as demonstrated by PNA-FISH. In many cases telomere signals were missing even when sister chromatids were strongly labeled. In addition, we used an internal PNA probe specific for the X chromosome, present in a single copy in these cells, in order to follow telomere dynamics on individual chromatids. High heterogeneity in telomere signals among individual X chromosomes as well as between their sister chromatids suggested sudden and stochastic loss or gain of telomere repeats. Such constant genomic instability often results in apoptosis and death of a fraction of cells present in the culture at all times. We discuss possible molecular mechanisms that may explain this observed telomere heterogeneity and possible adaptive repair mechanisms by which these cells maintain their chromosomes in order to survive such extreme and permanent genomic instability.
Alternative splicing of exon 3b gives rise to ODF2 and Cenexin
Authors: Hüber D. , Hoyer-Fender S.
Published: December 2007

ODF2 was first identified as the major component of the sperm tail outer dense fibers. Additionally, ODF2 is a critical component of the mature centriole of the animal centrosome where it locates to the distal appendages. Moreover, generation of primary cilia strictly depends on ODF2. The mature centriole is characterized further by recruitment of Cenexin. Albeit highly similar in sequence the relationship between ODF2 and Cenexin has not been investigated. We demonstrate here that ODF2 and Cenexin are alternative splice products by identifying a novel exon 3b encoding Cenexin specific amino acids. Even though ODF2 is the main isoform in testicular tissue RT-PCR analyses revealed that isoforms are not restricted to specific tissues.
The putative peroxisomal gene Pxt1 is exclusively expressed in the testis
Authors: Grzmil P. , Burfeind C. , Preuss T. , Dixkens C. , Wolf S. , Engel W. , Burfeind P.
Published: December 2007

Genes reported to be crucial for spermatogenesis are often exclusively expressed in the testis. We have identified a novel male germ cell-specific expressed gene named peroxisomal testis specific 1 (Pxt1) with expression starting at the spermatocyte stage during mouse spermatogenesis. The putative amino acid sequence encoded by the cDNA of the Pxt1 gene contains a conserved Asn-His-Leu (NHL)-motif at its C-terminal end, which is characteristic for peroxisomal proteins. Pxt1-EGFP fusion protein is co-localized with known peroxisomal marker proteins in transfected NIH3T3 cells. In addition, we could demonstrate that the peroxisomal targeting signal NHL is functional and responsible for the correct subcellular localization of the Pxt1-EGFP fusion protein. In male germ cells peroxisomes were reported only in spermatogonia. The Pxt1 gene is so far the first gene coding for a putative peroxisomal protein which is expressed in later steps of spermatogenesis, namely in pachytene spermatocytes.
Emergence of complex rearrangements at translocation breakpoints in a transgenic mouse; implications for mechanisms involved in the formation of chromosome rearrangements
Authors: Kasai F. , Yoshihara M. , Matsukuma S. , O’Brien P. , Ferguson-Smith M.A.
Published: December 2007

Cryptic complex rearrangements as a result of a reciprocal chromosome translocation have been characterised in a transgenic mouse strain. Analysis of the breakpoint junctions in our previous studies showed that the ada transgene was integrated at the breakpoint forming a fusion gene with Golga3 (Mea2). In this study, further detailed analysis around the translocation junctions revealed that the surrounding regions were composed of 13 fragments of defined transgenic chromosome origins over approximately 1.9-Mb areas. Exactly the same cluster structure of these 13 breakpoint fragments already existed in the second generation of the transgenic mice. Our results show that this highly complex rearrangement has been conserved as the incipient form without any additional changes for 18 years up to the present generation, suggesting simultaneous occurrence of multiple events in the founder mouse.
Localization of single-copy sequences on chicken synaptonemal complex spreads using fluorescence in situ hybridization (FISH)
Authors: Pigozzi M.I.
Published: December 2007

Synaptonemal complex (SC) spreads from bird oocytes and spermatocytes show the complete chromosome complement and can be observed at the light microscope using immunostaining of the proteins that compose the lateral elements. To investigate the use of avian SC spreads as substrates for fluorescent in situ hybridization (FISH) in combination with immunostaining, we applied two single-copy sequences to chicken oocyte spreads. Signals for both target sequences were consistently observed on the short arm of bivalent 1 in a large number of nuclei. Based on previous data about the size of chromosome 1 and from measurements on probed SC spreads, an estimate of the physical distance in Mb between each sequence and the telomere was calculated. The crossover frequencies along SC 1 obtained by immunolocalization of MLH1 foci during pachytene were used to calculate the distances in cM to the target sequences and to compare this cytogenetic SC map with the consensus linkage map for GGA1. The combination of SC-FISH and immunostaining could be generally applied to obtain high-resolution mapping of single-copy sequences in birds and, coupled with MLH1 crossover maps, it could be a reliable approach to obtain genetic distances between markers to test the genetic linkage maps generated from molecular markers.
Two rare aneutriploids in the unisexual Ambystoma (Amphibia, Caudata) identified by GISH indicating two different types of meiotic errors
Authors: Bi K. , Bogart J.P. , Fu J.
Published: December 2007

We report two types of aneutriploids in unisexual salamanders Ambystomalaterale-2jeffersonianum (LJJ) and Ambystoma 2 laterale-jeffersonianum (LLJ). One karyotype has 3n = 42: L27 (L8–); J15 (J8p+), and we suggest that it was induced by homoeologous pairing after premeiotic endomitosis followed by an unequal L8;J8 segregation. The second karyotype has 3n = 43: L14 (L10q); J29 (J12+), which can be explained by meiotic nondisjunction followed by unbalanced segregation. These two rare aneutriploids demonstrate two different types of meiotic errors that might help to explain the high mortality observed in this complex. Case one also indicates that contemporary intergenomic exchanges and homoeologous recombinations may occur after a premeiotic chromosome doubling event. Our study provides additional evidence for the extremely flexible reproduction of unisexual Ambystoma.
A haploid-diploid-triploid mosaic of the Amazon molly, Poecilia formosa
Authors: Lampert K.P. , Steinlein C. , Schmid M. , Fischer P. , Schartl M.
Published: December 2007

We report the finding of the first haploid-diploid-triploid mosaic fish from the family Poeciliidae. The animal was derived from a laboratory cross of a female F1 hybrid of Poecilia mexicana and P. latipinna with a male from an ornamental strain derived from P. mexicana and P. sphenops (Black molly). It was identified because of its unusual pigmentation pattern and molecular methods (flow cytometry, NOR staining) confirmed its mosaic genotype. The mode of mosaic formation and the possible importance for poeciliid fish evolution are discussed.