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Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 253 records · Page 14Linked to original sources
PubMed1984

Depressed NK cell activity of peripheral blood mononuclear cells in untreated hodgkin's disease: enhancing effect of interferon in vitro.

Natural killer (NK) cell activity of unseparated peripheral blood mononuclear cells from 30 untreated patients with Hodgkin's disease and 22 age- and sex-matched normal controls was evaluated using the classical K 562 cells as targets. A significant defect was demonstrated in the patients with stage I-II and seemed to be more profound in patients with advanced disease (stage III-IV) and in those with B symptoms. The differences between subgroups of patients, however, were not statistically significant, mostly because of the wide dispersion of individual data. Pre-incubation of effector cells with alpha A leucocyte recombinant interferon led to a clear increase in NK cell activity in 4 of 6 patients tested, showing that depressed NK activity in Hodgkin's disease is still susceptible to the enhancing effect of interferon, at least in some patients.

Adolescent↗
PubMed1984

Intracellular calcium measured with calcium-sensitive micro-electrodes and Arsenazo III in voltage-clamped Aplysia neurones.

Selected neurones of the abdominal ganglion of Aplysia californica were voltage clamped, injected with the Ca2+-indicator dye Arsenazo III, and impaled with Ca2+-selective micro-electrodes. Measurements of the absorbance signal (Arsenazo III) and Ca2+ micro-electrode potential during and following voltage-dependent Ca2+ influx (induced by voltage-clamp pulses) were simultaneously recorded. In neurones held at -50 mV, the mean intracellular free Ca2+ concentration [( Ca]i) measured by the Ca2+ micro-electrode was 0.18 microM, S.D. = 0.22 microM, n = 13. Bathing the cell in 0 Ca2+ artificial sea water (ASW) or intracellularly injecting EGTA decreased the resting [Ca]i. Voltage-clamp pulses, which maximally activated Ca2+ channels (from -50 to +30 mV), transiently increased both the Arsenazo III absorbance and the Ca2+ micro-electrode signals, indicating a rise in [Ca]i. Given the Ca2+ micro-electrode's limited band width, the peak of the Ca2+ signal during the pulse train could not be resolved; however, there was a net deflexion of this signal following the last pulse which slowly decayed to base line. Bathing the cells in 0 Ca2+ ASW, or reducing the driving force for Ca2+ entry (by stepping the voltage-clamp pulses to much higher membrane potentials) dramatically reduced both the absorbance and the Ca2+ micro-electrode signal increases. On the other hand, bathing the cells in 100 mM-Ca2+ ASW increased both signals. The intracellular Ca2+ gradient within the cytoplasm following voltage-clamp pulses was investigated by moving the Ca2+-selective micro-electrode tip in a step-wise manner relative to the membrane surface. The measured rise in [Ca]i was greatest near the membrane and not measurable within 40-50 microns of the membrane surface. The amplitude of the [Ca]i rise at different distances from the membrane could be fitted by a model based on a simple diffusion of Ca2+ from a plane source.

Action Potentials↗
PubMed1983

Spontaneous release of the Leu-2 (T8) molecule from human T cells.

Sensitive enzyme-linked immunosorbent assays (ELISA) for the detection of human T cell antigens in soluble form have been developed. The assays use mouse monoclonal antibodies and specific anti-Leu sera prepared in rabbits by immunizing with Leu antigens absorbed to monoclonal antibody affinity columns. With these assays, Leu-1, -2, and -3 antigen signals from extracts of as few as 5 X 10(3) cells could be detected. When culture supernatants from various cell lines were tested, Leu-2 antigen, but not Leu-1 or Leu-3, was found to be present. Leu-2 antigen was present only in supernatants from T cell lines that expressed Leu-2 on their cell surface. Leu-2 antigen accumulated progressively in the supernatant of low density culture and its presence did not depend on cell proliferation or on fetal calf serum in the culture medium. The Leu-2 antigen in the supernatant was found to have only one Leu-2a determinant, whereas Leu-2 antigen from cell extracts had at least two determinants. The Leu-2 molecule was effectively purified from supernatant with an anti-Leu-2a affinity column. The purified Leu-2 antigen from supernatant of HPB-ALL cells was a single polypeptide chain of 27,000 mol wt, whereas Leu-2 antigen present on HPB-ALL cell surface was composed of two or more identical polypeptide chains of 33,000 mol wt linked by disulfide bonds. Normal human sera and sera from leukemia patients were also examined for the presence of the Leu-2 antigen. Normal human sera contained low levels of Leu-2 antigen but sera from Leu-2-positive leukemia patients had high levels. These results indicate that Leu-2 antigen is released from human T cells under physiological conditions.

Animals↗
PubMed1983

Immunomodulating effects of a short-term oral treatment with C 1821 in untreated cancer patients: a controlled study.

C 1821 is a purified glycoprotein extract from Klebsiella pneumoniae serotype 2 with a molecular weight of about 350,000. It enhances immune responses in animals when given orally and the oral route of administration is devoided of any toxicity even in humans. The present controlled trial showed that C 1821 given per os at the single daily dose of 4 mg for 14 days in untreated cancer patients (mostly lymphomas) significantly enhanced delayed cutaneous hypersensitivity to recall antigens using the Multitest system (7 antigens). It also increased basal levels of lymphocyte cAMP and particularly of cGMP which were decreased in these patients. When incubated in vitro with lymphocytes from either normal controls or patients, C 1821 showed a dose-dependent stimulation of cAMP synthesis which was more pronounced in patients than in controls.

Adult↗
PubMed1983

Comparison of 11C and 14C-labeled fatty acids and their beta-methyl analogs.

1-[14C] beta-methylheptadecanoic acid ( [14C]BMHDA) was compared to 16-[14C]palmitic [( 14C]PA) acid for its biodistribution in rats, to determine whether an analogue designed to be trapped as a metabolite of the beta-oxidation metabolic process in the myocardium could be used to assess myocardial metabolic integrity. A heart concentration of 2.82 and 6.18% I.D./g at 5 and 60 min was observed for [14C]BMHDA, while [14C]palmitic acid was 2.65 and 0.89% I.D./g at 5 and 60 min respectively. However the myocardial concentration at 24 h was 0.4% I.D./g, indicating clearance of the tracer from the heart. Quantitative autoradiographic studies confirmed the highest heart concentration of [14C]BMHDA at 60 min, compared to other organs.

Animals↗
PubMed1983

Induction of cytogenetic effects in human fibroblast cultures after exposure to formaldehyde or X-rays.

Cytogenetic changes induced by formaldehyde (FA) in exponentially growing human fibroblasts were compared with those produced by X-rays. Chromosome aberrations of different types were detected. Exposure to 2 mM FA for 15 min resulted, quantitatively and qualitatively, in effects comparable to those produced by an X-ray dose of 100 rad. X-Rays at higher exposures produced types of chromosome aberrations that differed from those induced by higher exposures to FA.

Cells, Cultured↗
PubMed1983

Depressive episodes in patients with multiple sclerosis.

Thirty multiple sclerosis patients were assessed: 15 with predominantly cerebral involvement of their demyelinating disease and 15 with predominantly spinal cord and cerebellar involvement. The groups were matched with regard to age, duration of illness, and Kurtzke disability scores. Assessment included neuropsychological testing, the Beck Depression Inventory, and a psychiatric interview patterned after the Schedule for Affective Disorders and Schizophrenia. A group of normal volunteers served as controls for the neuropsychological testing. There were significantly more major depressive episodes in the cerebral group, as assessed by the patients' histories and by interview, and there was a trend toward more depressive symptoms in this group, as measured by the Beck inventory.

Adult↗
PubMed1983

Biosynthesis, glycosylation, and in vitro translation of the human T cell antigen Leu-4.

Two families of polypeptides were found in immunoprecipitates formed from human T cell lines by using the monoclonal antibody anti-Leu-4. When analyzed by one- and two-dimensional SDS-PAGE, the first family consisted of members with m.w. of 26,000 and isoelectric points that varied from very basic to acidic. The second family consisted of members with m.w. of 22,000 to 23,000 and isolectric points that varied from neutral to very acidic. The biosynthetic processing and intracellular glycosylation of several of these polypeptides were examined. Some, but not all, intracellular forms of the Leu-4 antigen contained N-linked oligosaccharides of the high mannose type. By using messenger RNA from human T cell lines, intracellular forms of Leu-4 were shown to be accurately translated and properly processed by Xenopus oocytes in vitro.

Animals↗
PubMed1982

The executive health examination.

An executive health examination scheme adopted by a large South African company is described. In a large percentage of executives irregularities were discovered on examination. It is questionable whether an extensive procedure is necessary, either as a screening process or as a health education session. These abnormalities could have been detected by simpler procedures. Through follow-up of anomalies found would be of greater benefit to both employer and employee than repeated examination of the whole population.

Administrative Personnel↗
PubMed1982

The nucleotide and amino acid coding sequence of a gene for H1 histone that interacts with euchromatin. The early embryonic H1 gene of the sea urchin Strongylocentrotus purpuratus.

We have determined the nucleotide sequence of the gene that codes for an H1 histone associated with euchromatin in the sea urchin Strongylocentrotus purpuratus. The gene codes for a protein of 205 amino acids. The nucleotide sequence of this gene is homologous to the sequence of H1 mRNA that is expressed during early embryonic development. We have compared the nucleotide and protein coding sequences of this H1 gene to those of the early H1 histone gene of the sea urchin Psammechinus miliaris. There is considerable drift by nucleotide substitution between the two genes randomly distributed across the mRNA coding region. Despite this divergence of nucleotide sequence, there are local constraints on amino acid substitutions throughout the molecule and especially in its central region. We have also compared the amino acid sequence in this central hydrophobic region of the euchromatic S. purpuratus H1 histone to the same region in H1 and H5 histones associated with heterochromatin. We show that certain amino acids are conserved and aligned in frameworks in all the sequenced H1 proteins.

Amino Acid Sequence↗
PubMed1982

Bidirectional tachycardia. Mechanism derived from intracardiac recordings and programmed electrical stimulation.

His bundle recordings and programmed electrical stimulation were performed in a 70-year-old woman with bidirectional tachycardia; the recordings demonstrated the infra-Hissian origin of the tachycardia. Occurrence of the His deflection slightly after the onset of ventricular depOlarization suggested that the origin of the tachycardia was located near the His bundle bifurcation. Recording of three atrial sites during tachycardia allowed the study of retrograde atrial activation. Two sets of fairly constant and alternating VA intervals were recorded. This fact is consistent with two ventricular circuits used alternatively. The tachycardia could also be interrupted with a single atrial or ventricular premature beat. It is postulated that the tachycardia is due to macroreentry involving the two fascicles of the left branch. This study suggests that reentry may be a possible mechanism in some cases of bidirectional tachycardia.

Aged↗
PubMed1982

[Mitral valve prolapse: do rhythm disorders have an electrophysiologic substratum?].

The mechanism of arrhythmias in mitral valve prolapse (MVP) is still unclear. The aim of this study was to determine if there were electrophysiological features common to patients with MVP. Eighteen patients with MVP documented on echo and angiocardiography underwent electrophysiological investigation. The series comprised 5 patients with ventricular arrhythmias and 5 with supraventricular arrhythmias, two of whom had ECG appearances of the Wolff-Parkinson-White, syndrome, and one a short PR interval. The RR interval, PR interval, intraatrial conduction (PA), atrio-hisian conduction (AH), intraventricular conduction (HV) the effective refractory periods of the atrium, AV node and ventricle, and the corrected sinus node recovery time were measured in the MVP group and in 20 presumed normal control subjects. There was a significant increase in the PR interval (p less than 0,05) at the expense of nodal conduction (AH) in the MVP group. In addition the Wenckebach point was significantly lower in this group. The other electrophysiological parameters in spontaneous rhythm and the atrial, AV nodal and ventricular refractory periods were the same in both groups. Sinus node function was comparable in both groups. In two patients without paiviously documented tachycardia, junctional tachycardia was initiated by provocative stimulation. However, no ventricular arrhythmias could be induced by pacing. A large number of preexcitation syndromes was observed in the MVP group (4/18), including one case of a latent Kent bundle, in patients with paroxysmal supraventricular tachycardias. On the other hand, the value of electrophysiological investigation seems to be limited for clarifying the mechanisms of the ventricular arrhythmias, probably because of their endomyocardial origin. Nevertheless, hemodynamic investigation showed abnormalities of left ventricular contraction in 4 of the 5 patients with ventricular arrhythmias.

Adolescent↗