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Biomedical subjects

M S Halpern

Publications and source records attributed to M S Halpern.

At least 55 records · Page 3Linked to original sources
PubMed1982

Abnormal Q waves in right sided chest leads provoked by onset of right bundle-branch block in patients with anteroseptal infarction.

In five cases of anteroseptal myocardial infarction complicated by intermittent right bundle-branch block, the onset of right bundle-branch block provoked the appearance of abnormal Q waves in leads V1 and V2, whereas a small initial R wave was present in the same leads during normal conduction. The intermittency of the conduction disturbance indicated that the Q waves were "right bundle-branch block dependent". It was also apparent that right bundle-branch block shifted the electrical location of the infarct towards the right, and made it look much larger. Right bundle-branch block dependent Q waves may arise during the acute stage of an anterior infarct suggesting, fallaciously, that an acute extension has occurred, or during the chronic stage, leading to the erroneous supposition that a new infarct had developed. The abnormal Q waves anteroseptal infarction complicated by fixed right bundle-branch block, though obviously related to the infarct, may be dependent on the right bundle-branch block.

Adult↗
PubMed1982

Modulation of parasystolic activity by nonparasystolic beats.

We studied 12 patients with ventricular parasystole in whom pacemaker activity could be modulated by nonparasystolic beats (NPBs). In six patients (group 1) in whom the intrinsic parasystolic cycle length (XX interval) was obtained without interposed NPBs, we found that NPBs falling during the first half of the cycle prolonged the XRX interval (containing one NPB) and that NPBs falling during the second half of the cycle abbreviated the XRX interval; both effects were maximal when NPBs fell close to the middle of the cycle and were separated by a reversal point. However, because of mutual interference between parasystolic beats and NPBs, only 13.2-43.4% of the parasystolic cycle could be effectively scanned. We also found that the XRX and RX intervals were linearly related. This relationship served to establish that in six patients in whom the XX interval was not obtained (group 2), modulation showed a similar behavior, although neither the reversal point nor the sense of the modulation could be determined. In this report, we suggest diagnostic criteria of parasystolic modulation.

Arrhythmias, Cardiac↗
PubMed1982

B cell expression of endogenous retroviral envelope antigen: biochemical and immunofluorescence characterization.

Plasma cells of line 15I5 chickens have been shown to express antigen that is cross-reactive with endogenous retroviral envelope glycoprotein. In the present study, we isolated this antigen and showed that it is structurally homologous to envelope glycoprotein. As assayed by immunofluorescence, most, if not all, of the plasma cell-associated envelope glycoprotein is present on the cell surface although it is not bound to surface Ig or Ia antigen. Although envelope antigen was not detectable by immunofluorescence on the surface of 15I5 bursal cells or peripheral B lymphocytes, immunochemical assays established that retroviral envelope glycoprotein is present on the surface of the bursal cells but at much lower levels than on the surface of the plasma cells. Both bursal and plasma cells synthesize envelope glycoprotein. These findings indicate that an increased level of expression of endogenous retroviral envelope glycoprotein is a concomitant of the differentiation of B lymphocytes to plasma cells in 15I5 chickens.

Animals↗
PubMed1981

Expression of endogenous retroviral envelope antigen in Ig(+) B cells of immunized 15I5 X 71 chickens.

In a previous study (1), we observed that antigen cross-reactive with structural protein of the endogenous retrovirus RAV-O is expressed in splenic Ig(+) B lymphocytes of immunized 15I5 X 71 chickens. The present experiments were undertaken to determine the relationship of this antigen to viral gag- and env-coded antigenic specificities. As analyzed by immunofluorescence with several antisera, group-specific determinants of the gp85 envelope glycoprotein as well as viral-related type E-specific determinants were detectable in islands of Ig(+) splenocytes; antigenic determinants of viral gag protein were not detected in the splenic islands. These observations indicated that antigen cross-reactive with endogenous retroviral envelope glycoprotein is expressed in Ig(+) B cells.

Absorption↗
PubMed1981

Endogenous retroviral envelope antigen in plasma cells.

Previous observations that endogenous retroviral envelope antigen is expressed in splenic Ig(+) B cells of SRBC-sensitized 15I5 X 71 chickens suggested that expression of this antigen might be a general property of plasma cells in 15I5 and related strains. To investigate this possibility, immunofluorescence assays with antiviral sera were carried out using plasma cells present in Harder glands. Endogenous retroviral envelope antigen was detectable in plasma cells of line 15I5 X 71, 15I5 X 72, and 15I5 chickens but not in plasma cells of line 72, 15B, or 63 chickens. Higher levels of retroviral envelope antigen were detectable in 15I5 X 71 plasma cells as compared to 15I5 X 71 bursal cells. The presence of retroviral envelope antigen in 15I5 plasma cells, coupled with the absence of detectable levels of retroviral p27-related antigen in these cells, suggested that expression of the former is governed by the ev 6 genetic locus.

Animals↗
PubMed1980

Unmasking of ventricular preexcitation by vagal stimulation or isoproterenol administration.

Twenty-one patients were studied in whom ventricular preexcitation (VP) had been recorded in the past and had later disappeared, indicating antegrade block in the accessory pathway (AP), either spontaneously (10 patients) or under the effect of chronic treatment with amiodarone (11 patients). VP reappeared in nine cases during vagal stimulation, and in five cases during an i.v. isoproterenol infusion. Retrograde conduction over the AP was studied in four of the remaining seven patients and was found to be present in three and absent in one. Although these patients differ from the ordinary patient with concealed AP in that antegrade preexcitation had been demonstrated in the past, this study suggests that concealed VP may result from the following mechanisms: 1) an extremely prolonged refractory period in the AP, causing a rate-dependent VP that can be identified during vagal stimulation; 2) a rate-independent depression of antegrade conduction that can be reversed by isoproterenol; 3) a depression of conduction that is apparently no longer reversible. Only in the latter case is a study of retrograde conduction needed to identify the concealed VP. These three mechanisms are likely to be a natural sequence of events leading to complete antegrade block in the AP.

Adult↗
PubMed1980

Effects of isoproterenol on abnormal intraventricular conduction.

An isoproterenol infusion (1.0-4.0 microgram/min) was administered to 15 patients with intermittent bundle branch block (BBB) and two patients with apparently fixed BBB. Three main effects were documented: (1) In all patients with phase 3, or tachycardia-dependent, BBB, isoproterenol caused a pronounced shortening of refractoriness in the affected fascicle. (2) In patients showing phase 4, or bradycardia-dependent, BBB, isoproterenol prolonged the phase 4 block range, probably because of enhanced diastolic depolarization. In one patient (four studies) in whom phase 4 block was not present, isoproterenol caused the appearance of a phase 4 block range. (3) In the two patients with fixed BBB, isoproterenol restored conduction, probably as a result of a hyperpolarizing effect. This study shows that isoproterenol tends to restore or improve conduction related to tachycardia-dependent block, but may impair conduction related to bradycardia-dependent block.

Bundle-Branch Block↗
PubMed1979

Endogenous oncornaviral antigen in the bursa of Fabricius of 15B X 7(2) chickens.

Oncornaviral antigen was detected in the bursal epithelium and in a subpopulation of bursal follicular cells of 15B X 72 chickens. This antigen is present in the bursal epithelium at 11 days of embryogenesis and persists there for at least 3 weeks after hatching. The absence of detectable antigen in the intestinal epithelium contiguous to the bursal epithelium indicates that the accumulation of viral antigen is a specific property of the bursal epithelium. The observation of C-type particles in the intraepithelial spaces suggests that the viral antigen in synthesized and assembled into virions by the bursal epithelial cells. In embryonic bursas, viral antigen-positve cells radiate from the surface epithelium toward the central region of the follicles. In bursas from post-hatch chickens, viral antigen-positive cells, including intrafollicular epithelial cells and cells resembling lymphocytes, are confined to the medullary region of the follicles.

Animals↗
PubMed1978

Immunogenicity of the envelope glycoprotein of avian sarcoma virus.

The expression of type E-specific glycoprotein in chick-helper factor-positive [chf(+)] chickens is not restricted to a certain stage of embryogenesis but persists in postembryonic life. This finding prompted an investigation of the immunogenicity of the viral envelope glycoprotein of exogenous avian sarcoma virus in chf(+) and chf(-) chickens. Sensitization of both classes of chickens resulted in the induction of detectable antibody reactivity to determinants of the glycoprotein that were type-specific as well as group-specific. Because group-specific determinants are present on type E-specific glycoprotein, these results link immunity to exogenous viral envelope glycoprotein in chf(+) chickens with autoreactivity. A model is proposed to rationalize the induction of reactivity in this system.

Alpharetrovirus↗
PubMed1978

Existence of automaticity in anomalous bundle of Wolff-Parkinson-White syndrome.

Escape beats probably arising from the anomalous bundle were documented in 2 patients with the Wolff-Parkinson-White (WPW) syndrome. A third patient, in whom complete AV block developed both in the anomalous bundle and the normal pathway, showed the occurrence of escape beats (an escape-bigeminy pattern), as well as a regular idioventricular rhythm arising from the anomalous bundle. Phase 4 block in the anomalous bundle occurred in 7 other patients, in 4 of them spontaneously and in 3 only after the administration of ajmaline or amiodarone. Only 4 of 14 fully investigated patients (out of a total number of 23) showed absence of both escape beats and phase 4 block. The escape beats were considered as direct evidence, and the phase 4 block as indirect evidence, for the existence of automaticity in the anomalous bundle. Such evidence supports the view that the anomalous bundle, like the His bundle-branch system, may be composed of specialised tissue endowed with the property of automaticity.

Adolescent↗
PubMed1977

Comparative effects of ajmaline on intermittent bundle branch block and the Wolff-Parkinson-White syndrome.

Phase 4 or phase 3 block or both occurred in the His bundle branch system of 11 patients with intermittent bundle branch block and in the anomalous bundle of 6 of 46 patients with the Wolff-Parkinson-White syndrome (13%). Administration of a single dose of ajmaline (50 mg intravenously) in these patients caused a similar response: expansion of the range of phase 3 and phase 4 block at the expense of the intermediate normal conduction range and total interruption of conduction in the affected fascicle when the effect of the drug was maximal. The great similarity in physiologic behavior and pharmacologic response in these groups of patients suggests that the anomalous bundle was probably diseased or abnormal in the six patients with Wolff-Parkinson-White conduction. In addition, ajmaline caused the first appearance of phase 4 or phase 3 block, or both, but not total interruption of conduction in 26 of the 46 patients with Wolff-Parkinson-White conduction (56.5%). Ajmaline does not cause fascicular block in normal subjects; thus this finding suggests either that the anomalous bundle is diseased or that the safety margin for conduction in the anomalous bundle is much narrower than in the bundle branch system. The conduction-depressing action of ajmaline may be greater at relatively rapid or relatively slow rates of stimulation, and smaller or absent at intermediate rates.

Ajmaline↗
PubMed1977

Antibody-independent detection of virus-specific glycoprotein synthesis is oncornavirus-infected cells.

A method is described for detecting the synthesis of avian and murine oncornavirus-specific glycoproteins without the use of antibodies raised against viral structural proteins. As applied to cells infected with avian tumor virus, the method served to resolve pr90, the precursor of the major envelope glycoprotein. A virus-specific glycoprotein of about 85,000 daltons, which has several properties expected to a precursor to gp69/71, was detected in cells infected with murine leukemia virus.

Alpharetrovirus↗
PubMed1976

Clinical efficacy of amiodarone as an antiarrhythmic agent.

Amiodarone, administered orally in doses of 200 to 600 mg/day, was remarkably effective in the treatment and prevention of a wide variety of atrial and ventricular arrhythmias. Total suppression and control was provided in 98 (92.4 percent) of 106 patients with supraventricular arrhythmias and in 119 (82 percent) of 145 patients with ventricular arrhythmias. The rates of total control of the arrhythmia were: 96.6 percent in 30 patients with recurrent atrial flutter or fibrillation, 96.6 percent in 59 patients with repetitive supraventricular tachycardia, 100 percent in 27 patients with Wolff-Parkinson-White syndrome and 77.2 percent in 44 patients with recurrent ventricular tachycardia unsuccessfully treated with other drugs. Excellent results were obtained in 6 to 8 patients with repetitive ventricular tachycardia and ventricular fibrillation related to postinfarction ventricular aneurysm and in 12 of 14 patients with ventricular extrasystoles and ventricular tachycardia related to Chagasic myocarditis. Amiodarone proved safe in patients with severe congestive heart failure and severe myocardial damage. Its clinical efficacy was related to its electrophysiologic properties and to two unique properties: its wide safety margin and its cumulative effect. The latter liberates patients from a rigid hourly schedule and provides for continuous antiarrhythmic control, days and even weeks after treatment is discontinued.

Amiodarone↗
PubMed1976

Chronic lymphocytic leukemia with gamma chain cytoplasmic inclusions.

A case of lymphocytosis diagnosed clinically as chronic lymphocytic leukemia is described. The lymphocytes possessed cytoplasmic inclusions that contained IgG-kappa immunoglobulin. Studies of immunoglobulin synthesis showed that the cells synthesized but did not secrete the immunoglobulin. The migration on poly.acrylamide gels of the IgG heavy chain was anomalous, and it is proposed that this interfered with its normal secretion and allowed the development of cytoplasmic inclusions within the cell. These findings are unique when compared with previous studies of immunoglobulin biosynthesis by normal or leukemic peripheral blood lymphocytes.

Blood Cells↗