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Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 289 records · Page 16Linked to original sources
PubMed1979

Long-term results of permanent atrioventricular sequential demand pacing.

Pervenous atrioventricular sequential demand pacemakers (AVSDPs) were implanted in 18 patients using an atrial electrode positioned in the right atrial appendage and a ventricular electrode positioned at the apex of the right ventricle. The indications included 13 patients with the sick sinus syndrome (72%), five of whom had the tachycardia-bradycardia syndrome, three with paroxysmal supraventricular tachycardia, one with cardiomyopathy and one with carotid sinus syncope. The follow-up ranged from 6 to 38 months, with a mean of 19.4 months (a total of 350 pacing months). Seventeen patients (94%) are asymptomatic. One patient had persistent episodes of paroxysmal supraventricular tachycardia. In the remaining patients with tachyarrhythmia, pacing alone (three patients) or in combination with antiarrhythmic drugs (four patients) controlled the tachyarrhythmia. There was one displacement of the atrial electrode (5.5%). Extrusion of the pacer occurred in three patients. It is concluded from this experience that AV sequential pacing is an effective technique and may be useful in patients with sick sinus syndrome, in patients with tachyarrhythmia and/or patients with poor myocardial function. However, continued research is needed to prolong battery life and to reduce the size of the pacemaker.

Aged↗
PubMed1979

Prevalence and causes of anemia in elderly hospitalized patients.

The prevalence and causes of anemia have been studied in 104 patients over 60 years of age admitted to a general medical ward in Jerusalem. In males and females, mean hemoglobin levels were about 1 g less than in the corresponding groups of healthy younger controls. A primary nutritional anemia could not be implicated in any of the 15 patients with hemoglobins below 11 g/dl. The most important causes of anemia were chronic renal failure, metastatic carcinoma, gastrointestinal bleeding, and infection. Conversely, in diseases with no adverse effect on erythropoiesis such as chronic ischemic heart disease, hypertension and diabetes, hemoglobin levels were equal to those of the younger controls. These findings indicate that although diminished serum iron and RBC folate levels may occasionally be found in elderly subjects, nutritional deficiency is seldom responsible for anemia in this age group in Israel- and anemia when present is often the manifestation of a chronic underlying disease.

Adult↗
PubMed1979

[Spontaneous transformation and long term culture of foetal mouse glial cells (author's transl)].

Six cell lines originated from foetal mouse brain were maintained in vitro for more than two years. The morphology of most of these cultures suggests their glial character. This is corroborated, for some lines, by the presence of specific glial protein (Glial fibrillary acidic protein, or GFAP). Five out of these lines remained not transplantable in animals during all the experiments. However one of them went through a spontaneous transformation at the eleventh population doubling. This culture, after transformation remained glial and when injected in animals, induced GFAP containing tumors.

Animals↗
PubMed1978

Cellular immunity in squamous cell carcinoma of the uterine cervix.

The thymus-dependent immunity of 42 patients with SCCC was evaluated by: delayed cutaneous reactions to ubiquitous antigens, DNCB sensitization, and lymphocyte response to PHA. In addition, T and B lymphocytes were detected in peripheral blood and in tumor sections, by adherence to E and HEAC. Depressed CMI was more intense in patients with disseminated disease, although a premature impairment of CMI was observed in some patients with initial-stage tumors. The absolute number of peripheral T lymphocytes showed association with both cutaneous reactions and PHA response. However, there appeared to be no significant correlation between the stage of the tumor and the pattern of adherence of E or HEAC to the biopsies.

Adult↗
PubMed1978

Sea urchin nuclei use RNA polymerase II to transcribe discrete histone RNAs larger than messengers.

RNA transcribed in isolated sea urchin nuclei and assayed by hybridization to histone genes cloned in E. coli contains sequences homologous to each of the five histone genes. Histone RNA is synthesized exclusively from the same DNA strand which is the template in vivo. Synthesis of the histone gene transcripts is sensitive to alpha-amanitin concentrations which inhibit RNA polymerase II activity. The fraction of histone RNA synthesized in vitro is comparable at two developmental stages to the fraction synthesized in vivo. The nuclear histone transcripts contain sequences homologous to spacer DNA regions present between the coding regions of the 6500 base pair (bp) histone gene repeat unit. The transcription of spacer sequences was demonstrated by hybridization of the nuclear transcripts to subcloned spacer DNA. Although the bulk of the RNA transcripts are greater than 2000 bases long, the histone-specific transcripts are of discrete sizes ranging from 100 bases to about 1100 bases long. Each histone gene hybridizes with at least one of the larger transcripts and with a different subset of smaller RNAs. We do not detect any giant polycistronic transcript spanning the entire histone repeat unit.

Amanitins↗
PubMed1978

Electrostatic interactions among hydrophobic ions in lipid bilayer membranes.

We have shown that the absorption of tetraphenylborate into black lipid membranes formed from either bacterial phosphatidylethanolamine or glycerolmonooleate produces concentration-dependent changes in the electrostatic potential between the membrane interior and the bulk aqueous phases. These potential changes were studied by a variety of techniques: voltage clamp, charge pulse, and "probe" measurements on black lipid membranes; electrophroetic mobility measurements on phospholipid vesicles; and surface potential measurements on phospholipid monolayers. The magnitude of the potential changes indicates that tetraphenylborate absorbs into a region of the membrane with a low dielectric constant, where it produces substantial boundary potentials, as first suggested by Markin et al. (1971). Many features of our data can be explained by a simple three-capacitor model, which we develop in a self-consistent manner. Some discrepancies between our data and the simple model suggest that discrete charge phenomena may be important within these thin membranes.

Bacteria↗
PubMed1978

Anatomical arrangement of muscle tissue in the anterior mitral leaflet in man.

Muscle tissue in atrioventricular (A-V) cardiac valve leaflets was studied in 35 human hearts and was found to be more prominent in the anterior leaflet of the mitral (MAL) than in the other valve leaflets. From serial sectioning and wax model reconstruction, the anatomic arrangement of the muscle in the MAL indicates bundles passing from the two commissural regions towards the mid-zone of the valve. Age did not appear to reduce the mass of muscle tissue in the MAL. The possibility of muscle contraction in the MAL increasing leaflet tension and accelerating post-artial movements received support by comparisons of the anterior and posterior leaflets of the mitral valve in their movements towards closure.

Adolescent↗
PubMed1977

[In vitro malignant transformation of fetal hamster brain cells by methylnitrosourea].

Using primary cultures originating from 14 day old fetal Hamster brain, we have obtained a cell line with glial morphology. These cell remain non transplantable during the first year of in vitro culture, but undergo spontaneous transformation during the second year. Following prolonged contact of the glial-like cells with 25 to 50 microgram/ml of methylnitrosourea (MNU), a malignant transformation is observed 5 months after the treatment. The lowest concentrations of (MNU) do not cause malignant transformation, but seem to inhibit (or postpone) the spontaneous transformation. After MNU treatment, cells retain their glial nature.

Animals↗
PubMed1977

Hamster cells, untreated and treated with chemical carcinogens, maintained in vitro for 2 1/2 years.

We have maintained in culture, for a prolonged period, untreated hamster cells from whole embryo, foetal brain and lung from newborn animals. Among the 7 lines studied we observed only one spontaneous transformation during the first year of culture. The cells of the 6 other control lines remained normal and diploid, and were not transplantable during the first 9 to 12 months of culture. After the 12th month, changes appeared in their in vitro behaviour and their transplantability: grafts of 0-5-2 X 10(6) cells induced tumours in the hamster; fewer cells did not. In vitro chemically transformed hamster cells were fundamentally different from untreated cells of the same origin, not only in morphological and growth characteristics but also in transplantability; of the 9 lines obtained, 7 induced tumours after injection of 10(1)-10(4) cells, and 2 after injection of 10(5) cells per animal.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1977

[Study of the antibody-dependent lymphocytotoxicity test as a function of the nature of the antibodies].

It is well known that IgM antibodies are inactive for the LDA test. Moreover, this work showed 7 S IgM to be just as inactive as 19 S IgM. With HLA antibodies, usually IgG, this work showed that the LDA test was not inhibited by a temperature of + 15 instead of + 37 degrees C. With cold lymphocytotoxic antibodies 19 S and 7 S IgM the LDA test was negative even at + 15 degrees C (optimum temperature for these complement dependant lymphocytotoxic antibodies) with or without prolonged incubation. Under these same conditions, a negative result was obtained using auto-lymphocytes as a target. Finally, our results confirmed that IgM antibodies with anti-HLA activity could not act as mediators even for targets with corresponding HLA activity.

Antilymphocyte Serum↗