Modulation of cardiac A1-adenosine receptors in rats following treatment with agents affecting heart rate.

Effects of chronic treatment affecting heart rate on A1 adenosine receptor levels and their functions were studied. Treatment of rats with isoproterenol for 10 days accelerated heart rate and increased the level of adenosine receptors, in both the atria and ventricles. Negative dromotropic response of isolated heart to adenosine was enhanced in isoproterenol-treated rats.

Constitutively active AMP kinase mutations cause glycogen storage disease mimicking hypertrophic cardiomyopathy.

Mutations in PRKAG2, the gene for the gamma 2 regulatory subunit of AMP-activated protein kinase, cause cardiac hypertrophy and electrophysiologic abnormalities, particularly preexcitation (Wolff-Parkinson-White syndrome) and atrioventricular conduction block. To understand the mechanisms by which PRKAG2 defects cause disease, we defined novel mutations, characterized the associated cardiac histopathology, and studied the consequences of introducing these mutations into the yeast homologue of PRKAG2, Snf4. Although the cardiac pathology caused by PRKAG2 mutations Arg302Gln, Thr400Asn, and Asn488Ile include myocyte enlargement and minimal interstitial fibrosis, these mutations were not associated with myocyte and myofibrillar disarray, the pathognomonic features of hypertrophic cardiomyopathy caused by sarcomere protein mutations.

Clonidine attenuates naloxone-induced opioid-withdrawal syndrome in cholestatic mice.

Cholestasis is associated with elevated plasma level of endogenous opioid peptides. Naloxone-precipitated withdrawal syndrome has been described in a mouse model of acute cholestasis. Thus we aimed at determining whether central noradrenergic hyperactivity is involved in manifestation of naloxone-precipitated withdrawal syndrome in mice with obstructive cholestasis.

Plasma atrial natriuretic peptide levels for predicting the outcome of atrial fibrillation.

The predictive value of plasma atrial natriuretic peptide (ANP) on the cardioversion outcome was evaluated in 46 hospitalized patients with recent-onset atrial fibrillation (AF). Cardioversion was successful in 42 (91%) patients, 7 (15%) of them regained sinus rhythm spontaneously. After 12 months, 14 (33%) cardioverted patients were in chronic AF.

Effect of ischemic stroke on the dynamic beat-to-beat QT-RR relationship.

The ECGs of 26 patients following ischemic stroke and 18 control patients with various orthopedic problems, all without primary heart disease, were examined to characterize the dynamic behavior of uncorrected QT interval in relation to changing RR interval during physiotherapy effort. ECG waveforms were analyzed to extract beat-to-beat QT and RR intervals. Based on performing multiple cross-correlations, the relationship between the RR and QT intervals was calculated using the following general formula QTi = c RRib-1.

Prognosis of patients with a recurrent acute myocardial infarction before and in the reperfusion era--a national study.

Background: Patients with recurrent acute myocardial infarction (AMI) are at increased risk for morbidity and mortality. We compared the outcome of patients with recurrent AMI hospitalized in coronary care units in the prereperfusion and reperfusion eras.

Methods: The study population comprised 2 large-scale cohorts with recurrent AMI: (1) 1415 (24%) of 5839 consecutive patients with AMI hospitalized in 1981 to 1983 (Secondary Prevention Reinfarction Israeli Nifedipine Trial [SPRINT] Registry) and (2) 1093 (25%) of 4317 patients with AMI from three national surveys performed in 1992 to 1996.

Non-traumatic lower limb older amputees: a database survey from a geriatric centre.

Purpose: The purpose of this survey was to examine the characteristic of a geriatric population admitted for amputation of a lower limb and to explore some of the factors that may affect the course of their hospital stay.

Method: The study took place in the geriatric division of a tertiary general hospital and included a close geriatric-orthopaedic liaison. Two-hundred and forty-one patients were included in the final analysis.

The relation of plasma total homocysteine levels to prevalent cardiovascular disease in older patients with ischemic stroke.

The objectives of this study were to describe the distribution of serum levels of total homocysteine (HCys) in a sample of older patients consecutively admitted following acute ischemic cerebral stroke, as compared with healthy controls, and to test for possible relationships of HCys levels to some of the prevalent cardiovascular diseases in these stroke patients. One hundred and thirty-seven stroke patients and 132 healthy controls (age > or =60) participated in this study. HCys levels were determined by HPLC method with fluorescence detection.

The effect of a chemical protective ensemble on intravenous line insertion by emergency medical technicians.

Protective gear is mandatory for medical personnel treating casualties in a contaminated environment. In the present study, we assessed the ability of emergency medical technicians to insert an intravenous line in this situation. Sixty emergency medical technicians were randomized to a control group, wearing fatigues, and a study group, wearing full protective gear.

Dynamic beat-to-beat QT-RR relationship during physiotherapy effort in elderly patients without primary heart disease.

The ECGs from 18 patients hospitalized in a rehabilitation setting, following surgery for hip fracture, were examined to characterize the dynamic behavior of uncorrected QT interval in relation to changing RR interval during physiotherapy effort. ECG waveforms were analyzed to extract beat-to-beat QT and RR intervals using a computerized ECG Analyzer (CEA-1100). The method of defining the QT and RR intervals is based on performing multiple cross-correlations that enable rejection of artifacts from the analysis.

Limb ischemia preconditions the heart against reperfusion tachyarrhythmia.

We investigated the hypothesis that a cardioprotective, antiarrhythmic effect might be obtained by brief ischemia of a remote part of the body before ischemia of the heart. Regional ischemia (RI) was induced in isolated Langendorff-perfused rat hearts: group I, 30-min RI and reperfusion (control hearts; n = 18); group II, 5-min RI before 30-min RI (a reference group of "classic" ischemic preconditioning; n = 12); and group III, ischemic preconditioning with in vivo 10-min limb ischemia (LI) before 30-min RI in the perfused heart (n = 20). A significant decrease in reperfusion arrhythmia was found in groups II and III compared with group I (P < 0.

Leukocytoclastic vasculitis after use of acetaminophen.

A patient with acute onset of purpuric rash and arthritis is presented. He was taking acetaminophen 10 days before the onset of the symptoms. The cutaneous lesions were caused by leukocytoclastic vasculitis on histologic examination.

Preconditioning in globally ischemic isolated rat hearts: effect on function and metabolic indices of myocardial damage.

We assessed the effects of ischemic preconditioning on heart recovery and metabolic indices of damage following global ischemia and reperfusion, in relationship to post-ischemic lactate release. Three groups of Langendorff rat hearts were studied: (1) A control group of 40 min global ischemia and 45 min reperfusion; (2) preconditioning by 5 min global ischemia and 15 min reperfusion prior to sustained ischemia and reperfusion; (3) Preconditioning by three episodes of brief ischemia-reperfusion prior to sustained ischemia. Repetitive episodes of brief ischemia-reperfusion were associated with increased reactive hyperemia, decreased release of purines and prostaglandin 6-keto F1 alpha, lower tissue glycogen but no change in lactate washout.

Prostaglandins and the antiarrhythmic effect of preconditioning in the isolated rat heart.

Our study evaluated the relationship between the endogenous production of prostacyclin and the antiarrhythmic effect of ischemic preconditioning against ischemic and reperfusion-induced tachyarrhythmia. Langendorff perfused rat hearts underwent 30 min regional ischemia with reperfusion. Preconditioning was induced by a single episode of 5 min ischemia and 15 min reperfusion.

Libman-Sacks endocarditis in the antiphospholipid syndrome: immunopathologic findings in deformed heart valves.

Objective: To examine the potential immunologic mechanism and involvement of antiphospholipid antibodies in the pathogenesis of heart valve lesions in patients with the antiphospholipid syndrome (APS).

Methods: Immunoperoxidase and immunofluorescence staining methods were used to evaluate 13 heart valve specimens derived from eight patients with the APS, either primary or secondary to systemic lupus erythematosus. Primary antibodies to human immunoglobulins, complement components, serum albumin and a monoclonal anti-idiotypic antibody to human anticardiolipin antibodies (aCL) were employed.

Brain and atrial natriuretic peptides in patients with ischemic heart disease with and without heart failure.

The objective of the study was the evaluation of natriuretic peptides in ischemic heart disease. Atrial and brain peptides (ANP, BNP) were elevated in patients with ischemic heart failure, as compared with patients with angina without over failure, and controls (p < 0.01).

Effects of brief and prolonged ischemia on eicosanoid synthesis in dog and rat hearts.

We compared the effects of brief and prolonged myocardial ischemia on tissue prostaglandin synthesis. Regional ischemia was induced in dogs and maintained for 5 or 30 minutes. Isolated rat hearts were subjected to global ischemia in a working heart preparation for periods of 5 or 20 minutes.

Adenosine, added to St Thomas' Hospital cardioplegic solution, improves functional recovery and reduces irreversible myocardial damage.

St Thomas' Hospital cardioplegic solution is commonly used to arrest hearts during surgery. Pursuing the hypothesis that the cardioprotective properties of adenosine could be a beneficial adjunct to a solution containing high K+ and Mg2+, we tested a low and a high adenosine concentration added to this cardioplegic solution, aiming at improved recovery of function and energy status. We arrested 18 working rat hearts by a 3-minute infusion with the solution without or with 50 microM or 5 mM adenosine.

Release of atrial natriuretic peptide in brief ischemia-reperfusion in isolated rat hearts.

We studied the effects of short-term global ischemia and reperfusion on ANP secretion from Langendorff-perfused rat hearts compared with isolated ventricles. Effects of regional ischemia, with or without increased atrial pressure, were examined in Langendorff-perfused and working heart models. Five minutes of global ischemia were associated with elevated levels of atrial natriuretic peptide (ANP) in the coronary effluent immediately and for approximately 10 min after resumption of reperfusion, resulting in a net hormone excess of 23 +/- 5 ng/g wet wt.

The effects of continuous operation in a chemical protective ensemble on the performance of medical tasks in trauma management.

Treating casualties in a chemically hazardous environment constitutes a unique problem. Physical protection of the medical personnel may impair their performance and potentially affect patients' prognoses. The present study examined the effect of prolonged physical protection on the accomplishment of medical tasks related to trauma management.

In vivo assessment of the inotropic and toxic effects of oxidized ouabain.

Oxidized ouabain, a product of the oxidative cleavage of the rhamnose ring in ouabain has been found to have a higher inotropic toxic ratio in cultured cardiac myocytes. The purpose of our study was to evaluate the efficacy and toxicity of oxidized ouabain in comparison with ouabain in intact animals. Drugs were infused to healthy cats; the positive inotropic effect, and the time-course of development of arrhythmia were followed and recorded until death.

Postexercise syncope: evidence for increased activity of the sympathetic nervous system.

This report describes an association of postexertional syncope with increased levels of circulating catecholamines. A 36-year-old male who experienced postexercise bradycardia and asystole had higher basal plasma norepinephrine (120 versus 68 +/- 6 pg/ml) and epinephrine (18 versus less than 10 pg/ml) but a similar vagal tone (vagal tone index of 5.44 versus 5.

The effects of powered air supply to the respiratory protective device on respiration parameters during rest and exercise.

The common chemical warfare protective masks impose an excessive respiratory load on the wearer due to elevated breathing resistance and increased dead space. For patients with severe respiratory disease, the excessive respiratory effort may be intolerable. Besides, the substantial negative pressure created within the mask during inspiration may result in an inward leakage in individuals having difficulties with proper facial fitting of the mask.

Medical limitations of gas masks for civilian populations: the 1991 experience.

Using a gas mask (GM) may involve considerable inconvenience, impairment of respiration and communication, and serious psychological reactions. The medical literature is primarily focused on the occupational aspects of using the GM by young and healthy workers. In contrast, there is hardly any information concerning the use of GMs by large, unselected populations, including children, the elderly, and the sick.