shukoor65/lab-rag-model huggingface dataset:
Dispersion of refractoriness in canine ventricular myocardium. Effects of sympathetic stimulation. In 18 dogs on total cardiopulmonary bypass, the average interval between local activations during artificially induced ventricular fibrillation (VF interval) was measured from extracellular electrograms, simultaneously recorded from up to 32 ventricular sites. VF intervals were used as an index of local refractoriness, based on the assumption that during ventricular fibrillation, cells are reexcited as soon as they have recovered their excitability. In support of this, microelectrode recordings in two hearts during ventricular fibrillation did not show a diastolic interval between successive action potentials. Refractory periods determined at a basic cycle length of 300 msec with the extrastimulus method correlated well with VF intervals measured at the same sites. Thus, this technique allows assessment of spatial dispersion of refractoriness during brief interventions such as sympathetic stimulation. The responses to left, right, and combined stellate ganglion stimulation varied substantially among individual hearts. This was observed both in dogs with an intact (n = 12) and decentralized (n = 6) autonomic nervous system. Individual ventricular sites could show effects of both left and right stellate ganglion stimulation (42% of tested sites) or show effects of left-sided stimulation only (31%) or right-sided stimulation only (14%). In 13% of sites, no effects of stellate stimulation were observed. Apart from these regional effects, the responses could be qualitatively different; that is, within the same heart, the VF interval prolonged at one site but shortened at another in response to the same intervention, although shortening was the general effect and prolongation the exception. Whenever sites responded to stellate ganglion stimulation with a shortening of VF interval, this shortening was approximately 10% for left, right, or combined stimulation, whether the autonomic nervous system was intact or decentralized. In six of 12 hearts in the intact group, there was a distinct regional effect of left stellate ganglion stimulation; in the other six hearts, the effects were distributed homogeneously over the ventricles. In three hearts, the effect of left stellate ganglion stimulation was strongest in the posterior wall, and in the other three hearts, in the anterior wall. The effects of right stellate ganglion stimulation were restricted to the anterior or lateral part of the left ventricle. Dispersion of VF intervals increased after left and combined stellate ganglion stimulation in the intact group and after right stellate ganglion stimulation in the decentralized group, but not significantly in every heart. This points to a marked individual variation with regard to the effects of sympathetic stimulation on electrophysiological properties of the heart.
Depressed contractile function due to canine mitral regurgitation improves after correction of the volume overload [published erratum appears in J Clin Invest 1991 Aug;88(2):723] It is known that long-standing volume overload on the left ventricle due to mitral regurgitation eventually leads to contractile dysfunction. However, it is unknown whether or not correction of the volume overload can lead to recovery of contractility. In this study we tested the hypothesis that depressed contractile function due to volume overload in mitral regurgitation could return toward normal after mitral valve replacement. Using a canine model of mitral regurgitation which is known to produce contractile dysfunction, we examined contractile function longitudinally in seven dogs at baseline, after 3 mo of mitral regurgitation, 1 mo after mitral valve replacement, and 3 mo after mitral valve replacement. After 3 mo of mitral regurgitation (regurgitant fraction 0.62 +/- 0.04), end-diastolic volume had nearly doubled from 68 +/- 6.8 to 123 +/- 12.1 ml (P less than 0.05). All five indices of contractile function which we examined were depressed. For instance, maximum fiber elastance (EmaxF) obtained by assessment of time-varying elastance decreased from 5.95 +/- 0.71 to 2.25 +/- 0.18 (P less than 0.05). The end-systolic stiffness constant (k) was also depressed from 4.2 +/- 0.4 to 2.1 +/- 0.3. 3 mo after mitral valve replacement all indexes of contractile function had returned to or toward normal (e.g., EmaxF 3.65 +/- 0.21 and k 4.2 +/- 0.3). We conclude that previously depressed contractile function due to volume overload can improve after correction of the overload.
Septic shock. Septic shock (SS) is the most common type of shock encountered by internists, and its prevalence appears to be increasing. SS complicates all types of infections. The hemodynamic characteristics of SS include a low systemic vascular resistance and an elevated, but relatively inadequate, cardiac output. A cardiomyopathy frequently occurs. The major endogenous mediator of SS is tumor necrosis factor, and interleukins-1 and -2 may also contribute. Important secondary phenomena include release of platelet activating factor, vasodilator prostaglandins, and upregulation of adhesion molecules on polymorphonuclear leukocytes and endothelial cells. Current therapy is often ineffectual, and potentially promising new therapeutic approaches are reviewed.
Clinical indications for cervical spine radiographs in alert trauma patients. Cervical spine fracture/dislocation is a potentially devastating injury that may be clinically difficult to diagnose. Therefore, a vast majority of trauma patients undergo cervical spine X rays when only a relatively small number of them will actually have a cervical spine injury. Because of the costly overuse of radiography, studies have been undertaken to define high yield criteria for evaluation of patients. This study examined the characteristics of acute cervical spine fracture/dislocation in alert trauma patients. Of 79 patients with this discharge diagnosis at St. Elizabeth Hospital Medical Center between 1982 and 1987, 47 met the criteria of Class I level of consciousness. All 47 patients complained of neck pain or demonstrated cervical tenderness to palpation. Other parameters (such as loss of consciousness, paresthesias, decreased sensation, weakness, cervical muscle spasm, decreased anal tone, and associated injuries) did not, individually or in combination with each other, consistently predict cervical spine injury. Although occult or painless cervical spine injuries have been reported in the literature, a careful review of these cases revealed that these injuries were not truly asymptomatic. Our study suggests that selected patients can be excluded from radiologic evaluation of the cervical spine. However, large prospective studies are needed to validate this finding.
Pacemaker failure on induction of anaesthesia. A patient with a permanent pacemaker presented for repair of a strangulated hernia. During induction of anaesthesia, the pacemaker generator stopped discharging, thus causing cardiac arrest. The likely cause of the generator failure was inhibition by suxamethonium-induced muscle fasciculations. Following defibrillation, and increase in stimulation threshold necessitated urgent insertion of a transvenous pacing system. It is suggested that, when suxamethonium is to be used in a patient with a permanent pacemaker, consideration should be given to reprogramming the pacemaker to asynchronous mode before induction of anaesthesia. If a patient with a pacemaker requires defibrillation, an acute increase in stimulation threshold may result and cause loss of capture. Rapid insertion of a transvenous pacing system may be necessary.
Shock wave-induced pancreatic trauma. A case is described of the appearance of a pancreatic or peripancreatic lesion after left renal calculus fragmentation by extracorporeal shock wave lithotripsy (ESWL). Its anatomical location and subsequent disappearance suggest it was related to trauma caused by the shock waves. The brief literature on pancreatic injury after ESWL is reviewed, and the role of the patient's underlying liver disease in the genesis of this complication is discussed.
Different types of skew deviation. Although all manifest skew deviations appear the same for the clinician, skew deviation can result from different combinations of dysconjugate vertical ocular deviations. Evidence is presented for three different types of skew deviation when it occurs as a feature of an ocular tilt reaction. In type 1 (utricle) there is upward deviation of both eyes with different amplitudes, as described for otolith Tullio phenomenon in humans. In Type 2 (dorsolateral medulla oblongata) hypertropia of one eye occurs while the other eye remains in the primary position, the hypothetical mechanism of skew deviation in Wallenberg's syndrome. In Type 3 (midbrain tegmentum) there is simultaneous hypertropia of one eye and hypotropia of the other eye, as described for electrical stimulation of midbrain tegmentum in monkeys and observed in clinical cases with a paroxysmal ocular tilt reaction.
Effect of P6 acupressure on postoperative vomiting in children undergoing outpatient strabismus correction. A prospective, double-blind study was conducted to compare the effect of pressure at the P6 (Neikuan) point with placebo as an antiemetic in children. Sixty-six patients, ages 3-12 yr, undergoing outpatient surgery for correction of strabismus, were allocated randomly to receive either bilateral P6 acupressure or placebo during the perioperative period. The study was designed to detect a 50% difference in the incidence of postoperative vomiting between the two groups, with a 90% power of achieving a statistically significant result at the 5% level (two-tailed). The incidence of postoperative vomiting for the placebo group was 58% before discharge from hospital, 73% at home and 82% in the first 24 h after surgery. The corresponding results for the acupressure group were 58% before discharge, 71% at home and 94% in the first 24 h. These differences were not significant; P6 acupressure did not reduce the incidence of postoperative vomiting in children undergoing strabismus surgery.
Prognosis for recovery from prolonged posttraumatic unawareness: logistic analysis. This study reviews the course and outcome of 130 patients who remained in a state of prolonged unawareness 30 days after severe cranio-cerebral trauma. Prognostic indicators and outcome were fitted by a logistic model. The significant prognostic factors observable in the first week after trauma were found to be ventilatory status, motor reactivity and significant extraneural trauma. The significant prognostic factors after the first month of unawareness were early ventilatory status, early motor reactivity, late epilepsy and hydrocephalus. The estimated probability of recovery of awareness (that is, consciousness) ranged from 0.94 in patients with early decorticate posturing in the absence of both extraneural trauma and ventilatory disturbance to 0.06 in patients with flaccidity, extraneural trauma and ventilatory disturbance in the first week after injury.
Coronary artery thrombolysis: comparison of approved agents. Three agents approved for the lysis of thrombi in coronary arteries--alteplase, anistreplase and streptokinase--have undergone critical clinical experimental trials in Europe and the United States. Global comparison of their efficacy shows that alteplase is slightly more effective (71 percent) in restoring patency than anistreplase (60 percent) and streptokinase (58 percent). Streptokinase and anistreplase are allergenic, and repeat administration is not feasible in the short-term, a distinct advantage for alteplase. More accurate dosing of thrombolytic agents and skillful use of aspirin and heparin improve the efficacy of thrombolytic therapy but can also increase the risk of bleeding. A recanalization rate of 90 percent or more could be achieved if the thrombolytic agent is administered within the first hour after thrombosis. Administration this soon after the development of thrombosis may be possible if the agent is given outside the hospital by practicing physicians or, perhaps, paramedics.
Preoperative prediction of pathological tumor volume and stage in clinically localized prostate cancer: comparison of digital rectal examination, transrectal ultrasonography and magnetic resonance imaging. Accurate preoperative staging is important for proper selection of patients for radical retropubic prostatectomy. Preoperative staging by digital rectal examination, transrectal ultrasound, magnetic resonance imaging (MRI), Gleason grade and prostate specific antigen was compared to pathological stage for 25 patients who underwent radical retropubic prostatectomy. The predictive value for tumor confinement was 36% by rectal examination, 37% by ultrasound and 30% by MRI. The predictive value for extracapsular disease was 100% by rectal examination, 83% by ultrasound and 66% by MRI. Preoperative determinations of tumor volume by any modality did not correlate with pathological tumor volume. Digital rectal examination, ultrasound and MRI clinically understage the disease in most patients but they may be reliable to predict extracapsular disease.
Sublaminar fixation in lumbosacral fusions. Sublaminar fixation to stainless steel rectangles was employed in an effort to improve the fusion rate in lumbar and lumbosacral arthrodesis. Thirty-seven patients had spondylolisthesis, and 26 had other causes of pain secondary to lumbar mechanical instability. Of the 63 patients, 53 achieved fusion and 52 had relief of pain. No infections or neurologic complications were encountered. This fusion rate of 84% does not significantly differ from rates obtained with noninstrumented methods, and this construct is no longer used for lumbar fusions.
Leber's hereditary optic neuropathy and Kearns-Sayre syndrome: mitochondrial DNA mutations. Mitochondrial DNA (mt DNA) supplies extranuclear (cytoplasmic) genes which program the manufacture of 13 of the 67 peptides of the mitochondrial respiratory enzymes. The remaining 54 are coded by nuclear DNA. All human children and adults, male and female, are entirely dependent on the cytoplasm of the ovum for their complement of mt DNA; the sperm contributes none. Accordingly, mutations in the mt DNA in a mother's ova will be passed on to all her children, although not all are clinically affected. Leber's hereditary optic neuropathy is in most cases due to a mutation that leads to the replacement of guanine by adenine at position 11778 in mt DNA. This causes histidine to be inserted instead of the normal arginine at the site of the 340th amino acid in the respiratory enzyme NADH subunit 4, hence its defective function. Other point mutations in the mt DNA coding for polypeptides of the respiratory chain complex or controlling sequences coded by mt DNA have been found in other families with Leber's hereditary optic neuropathy. Mitochondrial DNA is the site of other mutations as well. For ophthalmologists, the most important of these is the rare Kearns-Sayre syndrome (pigmentary retinopathy plus muscular dystrophies, especially of the extraocular muscles). Kearns-Sayre syndrome is due to deletions in the mt DNA, which vary in size and so affect a number of different respiratory enzymes, hence the variable manifestations. Cases are usually sporadic because the disease is often so severe that affected individuals do not reproduce if they survive, but in some cases inheritance from the mother has been reported.
Treatment of uterine leiomyomata with a luteinizing hormone-releasing hormone agonist: the possibility of nonsurgical management in selected perimenopausal women. OBJECTIVE: To evaluate the efficacy of luteinizing hormone-releasing hormone agonist (LH-RH-a) in the treatment of leiomyomata. DESIGN: A retrospective randomized trial. SETTING: Hospital department of obstetrics and gynecology. PATIENTS: Twenty-five women, ages 36 to 54 years with symptomatic uterine leiomyomata, were divided into two groups according to the responsiveness to LH-RH-a: group A patients reached menopause after LH-RH-a, whereas resumption of menstruation occurred within 12 weeks after cessation of therapy in group B. INTERVENTIONS: Luteinizing hormone-releasing hormone agonist was administered intranasally three times a day with 150 micrograms insufflation of one spray in each nostril (total dose: 900 micrograms/d). MAIN OUTCOME MEASURES: Efficacies of treatment were assessed in terms of uterine volume, hemoglobin concentrations, serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and bone density during and after treatment. RESULTS: In both groups, hemoglobin concentrations increased significantly after 16 weeks of treatment. A significant reduction in uterine volume was observed in both groups. After completing therapy, there was no further significant change in uterine volume in group A, whereas uterine volume in group B returned to pretreatment values. Serum LH and FSH concentrations were suppressed during treatment, but those gonadotropins in group A increased significantly up to the menopausal levels after treatment. Serum E2 concentrations in both groups showed consistent suppression by the end of the first treatment cycle. After cessation of therapy, serum E2 levels on group A remained in the castrate range, whereas E2 in group B returned to pretreatment levels, concomitant with the return of normal ovulation. CONCLUSIONS: Intranasal administration of LH-RH-a was successful in significantly decreasing uterine volume and increasing hemoglobin concentration in premenopausal women with leiomyomata.
Patterns of epithelial migration in the unaffected ear in patients with a history of unilateral cholesteatoma. Epithelial migration in a centrifugal manner is an established phenomenon in the normal human tympanic membrane. This pattern of migration is symmetrical in both ears of any one individual. We present a prospective study on the pattern of tympanic ink dot migration on the normal drum, in patients with a history of cholesteatoma in one ear. It was demonstrated that patients who develop cholesteatoma have a normal migratory pattern and rate in the unaffected ear. The conclusion from this study is that defective migration is not the initiating factor in the development of acquired cholesteatoma.
The use of CT scanning to triage patients requiring admission following minimal head injury. Recent data have suggested that patients with both a normal cranial CT scan and normal neurologic examination following minimal head injury (MHI) have no risk of neurologic deterioration. This study prospectively examined the safety of discharging patients from the emergency department (ED) after MHI whether or not there was a responsible observer at home. MHI was defined as a history of loss of consciousness (LOC), a Glasgow Coma Scale (GCS) score of 14 or 15, and no focal neurologic findings. In a 4-month period 111 patients with MHI were evaluated. Fifteen (14%) patients had a CT scan which revealed an intracerebral injury; 96 patients had a normal CT scan; five patients with normal CT scans were admitted because of persistent lethargy; and one patient was admitted after his CT that demonstrated an old infarct; the remaining 90 patients were discharged. There were 71 men and 19 women with a mean age of 29 years. The mechanism of injury was assault in 55, MVA in 30, and falls in five. The initial GCS in was 15 in 79 and 14 in 11. Fifty-eight per cent of patients were intoxicated. Fifty-seven (63%) patients were successfully contacted by telephone; none had developed any neurologic symptoms. Thirty-one patients who could not be followed up gave fictitious phone numbers. These data suggest that CT can reliably triage patients who can be discharged from the ED following MHI, even in the absence of a responsible observer. Hospital admission can be avoided in more than 80% of patients sustaining MHI, better utilizing scarce hospital resources.
Collateral circulation as a marker of the presence of viable myocardium in patients with recent myocardial infarction. The relationship between the presence of viable myocardium and the extent of coronary collateral circulation to the infarct area was evaluated in 20 patients with a recent anterior myocardial infarction who had complete obstruction of the left anterior descending coronary artery. The viability of myocardial tissue was assessed by exercise thallium-201 myocardial scintigraphy, and the collateral circulation was angiographically evaluated by means of a collateral index ranging from 0 to 3. Patients were divided into two groups according to the presence (group 1, n = 10) or absence (group 2, n = 10) of viable myocardium in the perfusion territory of the infarct-related artery. The collateral index in group 1 was 2.5 +/- 0.5 (SD), which was significantly higher than the 0.7 +/- 0.8 in group 2. These findings indicate that the presence of ischemic but viable myocardium is intimately related to the development of collateral circulation in patients with myocardial infarction, and the existence of well-developed collateral channels predicts the presence of viable myocardium in the infarct area.
Patient dose and associated risk due to radiological investigation of the internal auditory meatus. The radiation doses and associated somatic risks due to four radiological examinations for acoustic neuromata (AN) have been investigated. These examinations were (1) plain film radiography of the internal auditory meatus (IAM), (2) computed tomography (CT) of the IAM, (3) CT of the posterior fossa and (4) CT of the IAM with air contrast. Organ dose measurements were performed using lithium fluoride thermoluminescent dosemeters loaded in a patient equivalent phantom. Dose equivalents to various organs are presented, together with the effective dose equivalent and collective effective dose equivalent for each examination. Hypothetical fatal somatic risks for each examination studied here have been estimated from the effective dose equivalents. The estimated number of hypothetical fatal cancers induced by radiological examinations for AN is between approximately 110 and 820 times lower than the number of detected AN, depending on the method of assessing the radiation dose to the remainder organs. It is concluded that in this particular study the radiological examinations are of net benefit to this group of patients.
Hydatidiform mole and fetus with normal karyotype: support of a separate entity. Repetitive hydatidiform mole was observed in four pregnancies. The pregnancies presented with heavy bleeding and vomiting, but the post-evacuation courses were uncomplicated, with rapid regression of serum hCG levels. Cytogenetic investigations, analyses of restriction fragment length polymorphisms, and flow cytometry in three pregnancies were consistent with diploid, biparental conception as the origin of fetal tissue and molar and nonmolar villi. In one pregnancy, the analyses of cytogenetic markers suggested the coexistence of two different cell lines of dizygotic, biparental origin, whereas DNA analysis was consistent with a single conception. With incomplete genetic information, a hydatidiform mole with coexistent normal fetus is generally considered to result from dizygous twinning comprising an androgenetic complete mole and a normal conception. In the present gestations, the results based on several techniques applied on numerous samples from different tissues render this possibility unlikely. Some of the contradictions between histologic and cytogenetic classifications of hydatidiform mole may be explained by diploid, biparental partial mole, which seems to constitute a separate subgroup within hydatidiform mole. Following chorionic villus sampling or amniocentesis, continued pregnancy may be considered, depending on prenatal diagnosis including genetic marker analysis.