123rc/medical_text huggingface dataset:
Surgical options in postgastrectomy syndromes. The various operations performed for the treatment of peptic ulcer disease can lead to a variety of iatrogenic disorders collectively referred to as the "postgastrectomy syndromes." Although the etiology of most of these disorders remains unclear, loss of vagal innervation and bypass, ablation, or destruction of the pylorus clearly are involved in the pathogenesis of most, if not all, of these disorders. Unfortunately, there often is also a poorly understood psychological element involved in the pathogenesis. Of all ulcer operations, proximal gastric vagotomy results in the fewest physiologic abnormalities and the mildest postoperative symptoms. The continued popularity of this operation should effect a marked reduction in the incidence of disabling postgastrectomy syndromes. Fortunately, symptoms severe enough to necessitate remedial operation are uncommon, and conservative medical management is always indicated and usually suffices. When disabling symptoms are refractory, a thorough evaluation of the patient and an accurate classification of the syndrome are essential to guarantee a satisfactory result from surgical intervention. Although numerous surgical procedures have been developed to deal with the different syndromes, with varied results, the Roux-en-Y procedure has emerged as the operation of choice for most, if not all, postgastrectomy syndromes. However, the Roux-en-Y procedure has not been universally successful, and this operation can itself lead to the recently recognized postgastrectomy state of Roux-en-Y stasis syndrome. Prevention therefore remains the best form of therapy, and remedial operation should not be undertaken until adequate time has elapsed since the original operation and all forms of conservative treatment have failed.
Relative validity of self-reported snoring as a symptom of sleep apnea in a sleep clinic population The purpose of this study was to evaluate the relative validity of responses to three different questions about snoring as indicators for sleep apnea in a population referred to a sleep clinic. Secondary goals were to evaluate the meaning of a "don't know" response to these questions and to examine how the associations between snoring and sleep apnea are influenced by demographics. Results from 1,409 patients in a sleep clinic indicated that nearly all levels of estimated snoring frequency were associated with a greater likelihood of sleep apnea. In addition, a "don't know" response indicated a likelihood of sleep apnea. In the sample from this clinic, sensitivities approximating 90 percent were obtained in men, and specificities approximating 90 percent were obtained in women, but high diagnostic accuracy (high specificity in men; high sensitivity in women) could not be achieved with the three snoring questions used here. Generally, associations between snoring and sleep apnea were independent of age and sex. Single persons, persons living alone, and persons customarily sleeping alone of both sexes all showed associations between self-reported snoring and the presence of sleep apnea.
Aortic dissection with the entrance tear in the descending thoracic aorta. Analysis of 40 necropsy patients. Clinical and necropsy findings are described in 40 patients who had aortic dissection with the entrance tear in the descending thoracic aorta. Their ages at death ranged from 39 to 91 years (mean, 66 years); 24 (60%) were men and 16 (40%) were women. Systemic hypertension was present by history in 33 patients (83%) and the hearts were of increased weight in 78%. Of the 40 patients, 31 (78%) had no operative intervention, while 9 (22%) underwent operation for aortic dissection. Of the 31 patients without operative therapy, the diagnosis of aortic dissection was established in life in 9 patients (29%) and at necropsy in 22 (71%). The interval from aortic dissection to death was 30 days or less in 13 patients (42%); rupture of the false channel was the cause of death in 9 patients (69%), renal failure in 2 (15%), and the cause was unclear in 2 (15%). The interval from aortic dissection to death was more than 30 days in 18 (58%) of the 31 patients without operative therapy. The cause of death in these 18 patients was related to the dissection in 11 (61%) (rupture of the false channel in 5; renal failure from dissection in 3, and rupture of the false channel of a second acute dissection in 3), but in the other 7 patients (39%) death was unrelated to the dissection but a nonfatal complication, specifically stenosis of the true channel from compression by a thrombus-filled false channel, occurred in 4 of these 7 patients. Thus only 3 (10%) of the 31 patients without operative therapy had no complications of aortic dissection. All nine patients who underwent operation had had an aortic dissection within 30 days, and the operation was performed because of a major complication of the dissection. Four patients survived 8 to 84 months after the operation. Thus early operative intervention (before the appearance of complications) appears justified in patients with aortic dissection with the entrance tear in the descending thoracic aorta to prevent rupture of the false channel acutely or after initial healing; to prevent renal failure from compression of renal arteries by an aneurysmal false channel; to prevent true channel stenosis from compression by a thrombus-filled false channel; and possibly to prevent the recurrence of acute dissection.
Endobronchial carcinoid and mucoepidermoid carcinoma in children. Endobronchial neoplastic disease is rarely encountered in patients under 20 years of age. The great majority of these lesions are carcinoids or mucoepidermoid carcinoma. Symptoms are secondary to bronchial irritation and manifest as recurrent pneumonitis, hemoptysis, persistent cough, reactive airway disease, and chest pain. Early bronchoscopy reliably enables identification and may prevent harmful sequelae resulting from delay in diagnosis. Retrospective data from four cases collected from the Tumor Registry in the Southern California Kaiser Permanente Medical Group is presented and a review of the literature is discussed.
The effect of flunarizine on essential tremor. We investigated the effect of flunarizine treatment (10 mg/d) in 17 subjects with essential tremor in a double-blind placebo-controlled design. Tremor was assessed by clinical scoring, tremographic recordings, and subjective rating by subjects. Of the 15 subjects who completed the study, 13 showed improvement. We conclude that flunarizine is effective treatment for essential tremor.
Theophylline minimally alters contractile properties of canine diaphragm in vitro. We examined the effects of theophylline on contractile properties and high-frequency fatigue of canine diaphragm in vitro. Eighteen diaphragm muscle bundles were obtained from 10 anesthetized dogs and equilibrated in oxygenated Krebs solution to 100, 200, or 300 mg/l theophylline. These bundles were compared with 18 matched control bundles from the contralateral hemidiaphragm. No statistically significant differences in twitch tension, tetanic tension, twitch-to-tetanus ratio, time to peak tension, or half-relaxation time were observed. Concentrations of 300 mg/l theophylline, however, significantly (P less than 0.05) increased force production at 10 Hz by 32%. A similar tendency was present at lower concentrations and exhibited a clear dose-response behavior. High-frequency fatigue was similar in control and theophylline-treated bundles. We conclude that supratherapeutic in vitro concentrations of theophylline do not increase maximal tetanic tension and do not protect against muscle fatigue but potentiate relative force production at low stimulation frequencies. This relatively small effect cannot be explained by poor diffusion of the drug in the muscle bundle, because theophylline concentrations in the muscle bath and in the muscle bundle were virtually identical. Moreover, it remains unclear whether this potentially beneficial effect can be achieved at in vivo attainable serum concentrations.
Malignant thymoma presenting as intracardiac tumor and superior vena caval obstruction. A case of malignant thymoma with intracardiac infiltration and intrinsic superior vena caval obstruction due to the tumor is reported. Intracardiac invasion by a thymoma is rare and for this reason is believed worthy of a report.
Increased fatigue of isovelocity vs. isometric contractions of canine diaphragm. A comparison of fatigue as a loss of force with repeated contractions over time was performed in canine respiratory muscle by isometric (nonshortening) and isovelocity (shortening) contractions. In situ diaphragm muscle strips were attached to a linear ergometer and electrically stimulated (30 or 40 Hz) via the left phrenic nerve to produce either isometric (n = 12) or isovelocity (n = 12) contractions (1.5 s) from optimal muscle length (Lo = 8.8 cm). Similar velocities of shortening between isovelocity experiments [0.19 +/- 0.02 (SD) Lo/S] were produced by maximizing the mean power output (Wmax = 210 +/- 27 mW/cm2) that could be developed over 1.5 s when displacement was approximately 0.30 Lo. Initial peak isometric tension was 1.98 kg/cm2, whereas initial peak isovelocity tension was 1.84 kg/mc2 (P less than 0.01) or 93% of initial isometric tension. Fatigue trials of 5 min were conducted on muscles contracting at a constant duty cycle (0.43). At the end of the trials, peak isovelocity tension had fallen to 50% of initial isometric tension (P less than 0.01), whereas peak isometric tension had only fallen by 27%. These results indicate that muscle shortening during force production has a significant influence on diaphragm muscle fatigue. We conclude that the effects of shortening on fatigue must be considered in models of respiratory muscle function, because these muscles typically shorten during breathing.
Familial hemifacial spasm associated with arterial compression of the facial nerve. Case report. This report of an 88-year-old woman with familial hemifacial spasm includes the first published postmortem description of hemifacial spasm with cross-compression of the seventh cranial nerve root exit zone by a redundant loop of the anterior inferior cerebellar artery and associated vascular plexus. Histological examination of the seventh and eighth cranial nerve complex suggested nerve degeneration because increased numbers of corpora amylacea were present just distal to the compression concavity. There was no evidence of demyelination or gliosis of the nerve. This case suggests that vascular compression of the nerve root exit zone is an important condition in the etiology of most of these cases. This is the third reported case of familial hemifacial spasm; to date, all such patients have had left facial involvement. The family pedigree in this case suggests a pattern of autosomal-dominant inheritance with partial penetrance. The genetic basis for familial hemifacial spasm may involve anatomical variants or anomalies of the posterior circulation, since both posterior inferior cerebellar arteries were congenitally absent in this case.
Comparative clinical pharmacology of calcium channel blockers. Calcium channel blockers are effective antihypertensive agents, both as initial monotherapy and in combination with other antihypertensive agents. These drugs are also effective in the treatment of chronic, stable angina, variant angina and supraventricular arrhythmias. Drugs in this class have different affinities for calcium channels in vascular smooth muscle, cardiac muscle, cardiac sinus and atrioventricular node. They are all useful in hypertension and angina, but only verapamil and diltiazem are also useful in the control of heart rate and supraventricular arrhythmias. Nimodipine may control vascular spasm following subarachnoid hemorrhage. Calcium channel blockers have also been used in the treatment of migraine headache and Raynaud's phenomenon.
Electrocardiographic signs of atrial overload in hypertensive patients: indexes of abnormality of atrial morphology or function? Left atrial electrocardiographic (ECG) abnormalities have been reported as common findings in hypertension; however, their relationships with atrial anatomy are still uncertain. In addition, in arterial hypertension several studies demonstrated an abnormal left ventricular filling. The aim of this study was to investigate the relationships of the ECG signs of left atrial abnormality to atrial anatomy and left ventricular filling as evaluated by pulsed-wave (PW) Doppler in a group of patients with uncomplicated essential hypertension. To this end, 53 untreated essential hypertensive patients (age 44 +/- 8 years; blood pressure 160.5 +/- 21.5/104.7 +/- 13.5 mm Hg) underwent a complete 12-lead ECG and a PW Doppler study of the transmitral flow velocities. The ECG criteria of left atrial abnormality were: P wave wider than 0.12 (or 0.10) second or higher than 0.25 mV in lead II; P wave/PR segment ratio (Macruz index) greater than 1.6 in lead II; and P wave terminal forces in lead V1 equal to or more negative than 0.04. Echocardiographic measurements were made according to American Society of Echocardiography (ASE) convention. Doppler parameters of left ventricular filling were measured as E and A peak velocity, A/E ratio, and the ratio between the velocity-time integral under the E peak and that of the whole diastolic flow, which represents the rapid filling fraction (RFF). At least one ECG sign of atrial abnormality was present in 34 patients (64%); the Macruz index gave the most common ECG index of atrial abnormality (31 patients).
Long-term potentiation of electrotonic coupling at mixed synapses. Long-term potentiation of chemical synapses is closely related to memory and learning. Studies of this process have concentrated on chemically mediated excitatory synapses. By contrast, activity-dependent modification of gap junctions, which also widely exist in higher structures such as hippocampus and neocortex, has not been described. Here we report that at mixed synapses between sensory afferents and an identified reticulospinal neuron, the electrotonic coupling potential can be potentiated, as well as the chemically mediated excitatory postsynaptic potential, for a prolonged time period using a stimulation paradigm like that which produces long-term potentiation in hippocampus. The effect on coupling is due to an increase in gap-junctional conductance. Our data indicate that the potentiation of both synaptic components requires an increase in intracellular calcium, involves activation of NMDA (N-methyl-D-aspartate) receptors, and is specific to the tetanized pathway.
Relationship of tumor-cell ploidy to histologic subtype and treatment outcome in children and adolescents with unresectable rhabdomyosarcoma [published erratum appears in J Clin Oncol 1991 May;9(5):893] Clinical and histopathologic features are often inadequate for accurate prediction of relapse or survival of individual patients with rhabdomyosarcoma (RMS). We therefore studied the cellular DNA content (ploidy) of RMS cells in relation to histology and response to therapy in 37 patients with unresectable tumors. Using flow cytometric techniques, we found that about one third of patients had diploid tumor stem lines, regardless of the histologic subtype. In the group with abnormal ploidy, a hyperdiploid classification (1.10 to 1.80 times the DNA content of normal diploid cells) was exclusively associated with embryonal histology (P = .001). By contrast, near-tetraploidy (1.80 to 2.60 times the DNA content of normal cells) was strongly associated with alveolar histology (P = .001). Thus, in these histologic subtypes of RMS, abnormal ploidy appears to arise through different mechanisms. Tumor-cell ploidy had a significant impact on survival that was especially apparent in patients with unresectable, nonmetastatic (group III) tumors. In this subgroup, hyperdiploidy conferred the best prognosis and diploidy the worst (P less than .0001). None of the eight patients with diploid tumors survived for more than 18 months. Tumor-cell ploidy was the best predictor of treatment outcome for patients with either embryonal (P less than .001; relative risk, 25.5) or alveolar (P = .073; relative risk 7.1) RMS and contributed significantly after adjustment for disease stage and anatomic site. Patients with unresectable diploid RMS have an unacceptably high risk of treatment failure, justifying new therapeutic approaches for this distinct subgroup.
Frequency of recovery of Blastocystis hominis in clinical practice. We examined the frequency of isolation of Blastocystis hominis from stools of patients seen in an indigent-care teaching hospital. Over a 2-year period, 2,744 stool specimens were examined prospectively. B. hominis was found in 262 stools (9.5% of all stool specimens and 53.5% of the positive specimens). Clinical data were obtained from 80 patients with stools positive for B. hominis. B. hominis was the only parasite isolated in 39 of 47 (83%) of the adults, compared with 17 of 33 (52%) of the children (p = 0.006). All but 2 of 52 patients without concomitant parasitic infection or bacterial pathogens in stool had gastrointestinal symptoms (41 abdominal pain, 26 diarrhea, and 5 vomiting), but no association was seen with fever, peripheral leukocytosis, stool occult blood, fecal leukocytes, or endoscopic or radiologic evidence of colitis. Therefore, B. hominis was frequently recovered from stools examined in a hospital clinical parasitology laboratory. The clinical presentations of patients in our series did not suggest that B. hominis was invasive. Most patients with B. hominis probably do not require treatment since they will either have spontaneous resolution of symptoms or will be found to have an alternative explanation for their problem.
Diet, smoking, and alcohol: influence on coronary heart disease risk. The Framingham study on coronary heart disease (CHD) has shown that life-style, particularly diet, smoking, and alcohol consumption, has a great impact on the incidence of CHD. Blood lipoproteins, rather than total blood cholesterol, have been found to be more accurate predictors of CHD risk. Blood triglyceride, previously considered to have little bearing on CHD risk, was found to have a negative impact in many cases. A population subgroup with high triglyceride greater than or equal to 1.7 mmol/L (greater than or equal to 150 mg/dL), low high-density lipoprotein less than or equal to 1.04 mmol/L (less than or equal to 40 mg/dL), increased insulin resistance, and a higher incidence of diabetes mellitus has been found to be at increased risk for CHD. Diet intervention trials have shown that a reduction in total cholesterol and saturated fat consumption produced reduction in CHD incidence proportionate to the fall in cholesterol. Cigarette smoking increased CHD risk moderately; those who smoked one pack per day had twice the risk of nonsmokers. Alcohol consumption actually lowered CHD incidence in the Framingham study; however, when alcohol consumption was greater than two drinks per day, a rise in mortality from cancer and stroke was observed.
Tolerance to organic nitrates: evidence, mechanisms, clinical relevance, and strategies for prevention. OBJECTIVE: To review the available information about nitrate tolerance, its potential mechanisms, clinical implications, and strategies for prevention. DATA IDENTIFICATION: A survey of the National Library of Medicine MEDLINE database and bibliographies of the reviewed articles. STUDY SELECTION AND DATA EXTRACTION: Studies were selected from the English language literature with an emphasis on recent studies and, when available, randomized placebo-controlled studies. Old studies were selected on the basis of their historical value and originality. A total of 134 retrieved articles were considered relevant and were reviewed in depth. RESULTS: The available information about the experimental as well as the clinical evidence for tolerance to organic nitrates has been summarized. In addition, information related to potential mechanisms, clinical implications, and possible methods for prevention have been reviewed. CONCLUSIONS: Evidence indicates that prolonged in-vitro exposure to organic nitrates, continuous intravenous or topical administration of nitrates, and frequent in-vivo oral dosing result in the rapid development of tolerance to the peripheral as well as to the coronary vasodilatory effects of the drugs. This phenomenon leads to the rapid attenuation of the hemodynamic and anti-ischemic effects of nitrates in patients with ischemic heart disease or congestive heart failure, or both. Tolerance development seems to be dose- and time-dependent, and its main mechanism seems to be a depletion of sulfhydryl groups at the vascular cell. Although the repletion of sulfhydryl groups with the use of sulfhydryl-containing drugs may help to prevent tolerance, the efficacy and safety of this approach requires further evaluation. Intermittent therapy allowing a sufficiently long, daily nitrate-washout interval seems to be the most effective and the most safe strategy currently available for the prevention of nitrate tolerance.
Use of arterial compliance for evaluation of hypertension. Arterial compliance describes a change in the volume of arteries following a change in blood pressure. The physical basis of the compliance concept and experimental procedures in animals both indicate that the relation between arterial compliance and blood pressure pattern is often unclear. Compliance is pressure-dependent because of the biphasic elastin and collagen composition of arteries and, hence, decreases when blood pressure increases. Compliance also determines the pulsatile amplitude of the pressure wave by regulating the buffering function of an artery's face to the cardiac pump and, accordingly, its reduction induces a selective increase in systolic level. The questions are whether these theoretical and experimental phenomena can be extrapolated to human hypertension and whether they can be assessed from indirect measurement of arterial compliance by means of a time-domain analysis of arterial pressure and flow waves via various models of the arterial tree. Whatever the method and site of measurement, arterial compliance was found to be decreased in different forms of hypertension. This low compliance can be considered to have a causal role in elderly patients with isolated systolic hypertension. In contrast, in patients with systolo-diastolic hypertension physiologic and pharmacologic arguments exist against the fact that low arterial compliance may be the pure consequence of mean blood pressure elevation. Moreover, it is suggested that aging acts in concurrence with pressure elevation to decrease arterial compliance, and that in certain hypertensive patients additional factors, perhaps atherosclerotic in nature, contribute to impair the elastic properties of arteries.