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Biomedical subjects

J Levy

Publications and source records attributed to J Levy.

At least 559 records · Page 31Linked to original sources
PubMed1975

Correlation of serum creatinine concentration and amikacin half-life.

The half-life of amikacin in serum has been measured following the administration of a single intravenous injection of 7 mg/kg in nine adult patients with varying degrees of renal function impairment and in four patients with normal renal function. A linear relationship between the half-life and the serum concentration has been found, suggesting that half-life of amikacin in serum can be calculated by multiplying the serum creatinine (in mg/100 ml) by 3.

Adult↗
PubMed1975

Induction of erythroid differentiation by dimethylsulfoxide in cells infected with Friend virus: relationship to the cell cycle.

Cells infected with Friend virus can be induced to erythroid differentiation by culture with 2% dimethylsulfoxide. This study was designed to determine if dimethylsulfoxide causes the expression of erythroid differentiation by an effect on a particular phase of the cell division cycle. The infected cells were synchronized by exposure to 2 mM thymidine. It is shown that dimethylsulfoxide must be present during DNA synthesis (S-phase) and, possibly, shortly thereafter, to induce differentiation assayed by measuring hemoglobin synthesis. In order to achieve an effective intracellular incorporation of dimethylsulfoxide, cells must be exposed to the agent for at least 24-30 hr before the critical S phase. It is suggested that induction of erythroid differentiation in cells infected with Friend virus involves an effect of dimethylsulfoxide, or a metabolic product, that alters the program of transcription, during or immediately after DNA synthesis.

Cell Differentiation↗
PubMed1975

Induction of erythroid differentiation in murine virus infected eythroleukemia cells by highly polar compounds.

Murine-virus-infected erythroleukemia cells cultured in a medium with dimethylsulfoxide or N,N-dimethylformamide are induced to differentiate to erythroid cells. A number of highly polar compounds have a similar effect in inducing erythroid differentiation of the virus-infected cells, as assayed by the appearance of hemoglobin. These compounds are 1-methyl-1-2-piperidone, N,N-dimethylacetamide, N-methylpyrrolidinone, N-methylacetamide, 2-pyrrolidinone, propionamide, pyridine-N-oxide, piperidone, N-methylformamide, acetamide, and triethylene glycol. It has been previously reported that dimethylsulfoxide must be present during DNA synthesis and, possibly, shortly therafter, to induce differentiation. These findings are consistent with the hypothesis that dimethylsulfoxide and related polar compounds act by changing the conformation of DNA or a DNA-protein complex, causing an alteration in transcription that leads to the expression of the program of erythroid differentiation.

Acetamides↗
PubMed1975

A human adrenocortical adenoma in tissue culture. Morphology and hormone secretion.

A human adrenocortical adenoma was cultivated in vitro and the morphological characteristics, steroidogenic activity and response to ACTH of the cultured cells were studied over a period of about two months. At first, the morphology of the cultures was similar to that of the original tissue. This structure changed in the course of time and the cells underwent fibroblastoid transformation. Stimulation with ACTH evoked two types of morphological response: a) a short-term response, whereby an extensive but rapidly reversible vacuolization was followed by cell enlargement and granulation, and b) a long-term effect in which the differentiated cell morphology was maintained. The cultures showed a low steroidogenic activity throughout the experiment. ACTH stimulation increased the total 17-hydroxysteroid production up to 10-fold. After ACTH withdrawal the corticosteroid levels declined slowly and about 50% of the maximal activity persisted on the fifth day after ACTH withdrawal.

Adenoma↗
PubMed1975

In vitro biosynthesis and release of three immuno-reactive insulin-like components by a human insulinoma.

Pieces of a human insulinoma were incubated for 120 or 180 min in media containing labelled leucine. In addition to insulin and proinsulin, the tumoral tissue was found to synthesize and release a third immunoreactive insulin-like component of higher molecular weight. No significant amount of the latter component was detected in normal rat islets under identical experimental conditions. The rate of secretion of insulin-like peptides was abnormally high relative to their concentration in the tumoral tissue, and was apparently unaffected by various insulinotropic or inhibitory agents. Only cycloheximide was found to significantly reduce the synthesis and subsequent release of insulin-like peptides by the tumoral tissue. It is suggested that the secretion of large amounts of both the high molecular weight component and proinsulin relative to that of insulin might be due, in part at least, to the inability of the tumoral cells to prevent the release of newly synthetized hormonal peptides, leading to the depletion of the tissue in hormonal products, as judged by both immunological and ultrastructural criteria.

Adenoma, Islet Cell↗
PubMed1975

Susceptibility of newborn and adult guinea pigs to Mycobacterium intracellulare and M. kansasii.

Six groups of guinea pigs, each consisting of 30 3-month-old and 20 7-day-old animals, received intraperitoneal inoculations with one of four strains of Mycobacterium intracellulare or one of two strains of M. kansasii. Three similar control groups received either an intraperitoneal injection of M. tuberculosis, no injection, or a sterile injection. Guinea pigs were sacrificed at 3, 5, 10, 20, 30, and 90 days. Lungs, spleen, liver and peritoneal fluid were cultured. Lungs were also examined histologically for inflammatory response. All the guinea pigs sacrificed within 20 days after inoculation showed positive cultures at nearly all sites. Thirty days after inoculation significantly more of the young guinea pigs had positive cultures, and the distribution of mycobacteria in their tissues was wider than was observed with the adult animals. At 90 days, the bacteriological results were similar for both groups. This histological findings were generally similar for both age groups, although acute reactions persisted longer in the young animals. All guinea pigs injected with M. tuberculosis died spontaneously within 90 days after inoculation and showed positive cultures at all sites. The results of the present study indicate that young guinea pigs are more susceptible to M. intracellulare and M. kansasii than are adult animals and should be preferred to old animals for diagnostic inoculations.

Age Factors↗
PubMed1974

The effect of erythropoietin on colonial growth of erythroid precursor cells in vitro.

A method is described for the colonial growth, in semi-solid medium, of erythropoietin-responsive erythroid cell precursors. The erythroid cell precursors were isolated by immune hemolysis from fetal mouse liver. Both the number of precursor cells triggered to proliferate and differentiate, and the size of the erythropoietic colonies formed, are directly dependent upon the concentration of erythropoietin included in the culture.

Animals↗
PubMed1974

Human lymphocyte subpopulations. Effect of corticosteroids.

Normal subjects given 60 mg of prednisone orally at 8:00 a.m. developed a transient lymphopenia at 2:00 p.m. To define the populations of lymphocytes affected the number and type of lymphocytes in the peripheral blood were assayed. "Late" and "early" spontaneous sheep red blood cell rosettes were used as markers for thymus-derived (T) lymphocytes and one of its subpopulations, respectively. Receptors for aggregated gammaglobulin and complement identified bursal-equivalent or bone marrow-derived (B) lymphocytes and one of its subpopulations, respectively. 6 h after administration of 60 mg of prednisone, the blood samples showed a decrease in proportion of T cells from 69.2 +/- 2.1% to 55.9 +/- 2.8% (average +/- SE) and an increase in B-cell proportion from 21.3 +/- 2.0% to 44.8 +/- 4.1%. The changes of "early" rosettes and complement receptor lymphocytes also paralleled these. In all cases the absolute numbers of T cells and of B cells were decreased by prednisone. The density gradient distribution of the lymphocytes did not change after prednisone. These data indicate that both T and B lymphocytes are affected by the prednisone but that the T cell lymphopenia was more pronounced. The lymphopenia might reflect either sequestration in the marrow and/or transient arrest of recirculation.

B-Lymphocytes↗