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Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 307 records · Page 17Linked to original sources
PubMed1976

Quantitation of labeled globin messenger RNA by hybridization with excess complementary DNA covalently bound to cellulose.

A method is described to quantitate labeled globin mRNA by hybridization with excess cDNA which was enzymatically polymerized on oligo(dT)-cellulose. In a large excess of cDNA-cellulose the rate of RNA hybridization was dependent on DNA concentration and not on RNA concentration. Nonhybridized RNA can be digested by RNase and washed from the cDNA which is covalently bound to cellulose. This enables the detection of labeled globin mRNA even when present in a porportion as low as 0.02-0.03% of the total RNA.

Animals↗
PubMed1976

Biosynthesis and stability of globin mRNA in cultured erythroleukemic Friend cells.

Biosynthesis and stability of the mRNA population in DMSO-induced Friend erythroleukemic cells were studied after labeling the RNA with 3H-uridine and then chasing it with nonlabeled uridine. Globin RNA metabolism was studied by hybridization to excess complementary DNA convalently coupled to oligo(dT)-cellulose. After a labeling period of 120 min, 2-4% of the poly(A)-containing labeled RNA was in globin RNA; it decayed with a half-life of 16-17 hr. The rest of the poly(A)-containing RNA was composed to two kinetic populations: 85-90% decayed with a half-life of about 3 hr, while 10% decayed with a half-life of about 37 hr. The portion of globin RNA in labeled poly(A)-containing RNA behaved in an unexpected fashion during the chase period. During the initial chase period, the percentage of globin RNA increased rapidly, reaching a maximum of about 15% at 20 hr, but it subsequently declined gradually. Based on these findings, a model was built that describes the changes in the proportion of globin mRNA in poly(A)-containing RNA during continuous synthesis and after chase of the labeled RNA. It appears that if the parameters described remain constant during the maturation of erythroblasts, then this model would not account for the almost exclusive presence of globin RNA in the reticulocyte. By far the most effective way to achieve this high level of globin RNA is the destabilization of the mRNA population which is more stable than globin RNA, and not the stabilization of globin RNA itself.

Cell Line↗
PubMed1976

[Electrophysiologic study of fenoxedil chlorhydrate].

Electrophysiologic studies were carried out on 10 patients before and during therapy by Fenoxedil Chlorhydrate a new anti-arrhythmic drug, to determine the effects on cardiac conduction. Fenoxedil Chlorhydrate produces a constant alteration of intra-nodal conduction. Modification of sinus function are less evident. Auricular and ventricular refractory periods are increased in the majority of cases. These results give a better understanding of mecanism of this drug, and helps in its prescription in clinical practice.

Anti-Arrhythmia Agents↗
PubMed1976

[Study of the foeto-maternal immunization using the LDA test (author's translation)].

In this work, sera of primiparous and multiparous women are studied by the aid of a LDA test and the results are compared to those obtained by the classical technique of complement dependent lymphocytotoxicity. Specificities, that complement dependent lymphocytotoxicity is unable to prove, are checked by the LDA test. Its higher senstivity is confirmed without contradicting the complement dependent lymphocytotoxicity conclusions.

Adult↗
PubMed1975

[Spontaneous growth of suspended hamster embryonic cells transformed in vitro by methyl-7 benzo(a)anthracene].

A transformed and malignant cell line was obtained by treatment of secondary hamster embryo cells with 7-methyl benz(a)anthracene (10 mug/ml of medium). Later on these cells acquired the capacity to grow spontaneously in suspension and form "spheroids". The evolution of this cell line showed similarities between the carcinogenic process in vitro and in vivo.

Benz(a)Anthracenes↗
PubMed1975

Individual histone messenger RNAs: identification by template activity.

Newly synthesized polysomal messenger RNAs from cleavage stage embryos of the sea urchin Arbacia punctulata and Lytechinus pictus that contain putative histone mRNAs have been fractionated on 6% polyacrylamide slab gels. At least 8 RNA species with unique electrophoretic mobilities have been recognized. The complex of RNAs has been eluted from the gels in three groups, A, B, and C, in increasing order of mobility. The template activity of the three fractions and the unfractionated starting material was examined in the mouse Krebs II ascites tumor cell-free protein synthesizing system. The unfractionated messenger complex programs the synthesis of proteins that co-electrophorese exclusively with sea urchin histones in both sodium dodecyl sulfate and acid urea gel systems. The products of in vitro protein systhesis stimulated by the individual polyacrylamide gel RNA fractions were similarly examined. Each stimulated protein synthesis and was enriched for specific histone templates. We conclude that RNA fraction A is template for histone f1, C is template for histone f2a1, and B serves as template for f2b, f2a2, and f3 histones. A minor degree of contamination of the A and B RNA fractions was obvious from the production of other histones by each template. The co-electrophoresis of specific template activity with specific radiolabeled RNAs supports the concept that most or all of the labeled RNAs are indeed themselves the histone mRNAs.

Animals↗
PubMed1975

Nutritional survey in an iron- and folate-deficient population.

A high prevalence of folate and iron-deficiency anemia was found in women and children of Kiryat Shmoneh, an Upper Galilee community. Malnutrition was assumed to be partially responsible for these deficiencies. To verify this assumption, a detailed nutrition survey was carried out in 30 families, comprising 232 individuals in this community. A low overall caloric intake was found in 30% of the population studied. The dietary folates consumed were much below the recommended dietary allowance in all subjects. In over 60% of the subjects investigated, the daily iron intake was also below the recommended allowance. These data support the role of malnutrition in the development of folate and iron deficiencies in the community studied.

Adolescent↗