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Biomedical subjects

J Malec

Publications and source records attributed to J Malec.

At least 55 records · Page 3Linked to original sources
PubMed1980

Intragenomic distribution of 5-methylcytosine in various forms of human and murine leukemic cells.

The degree of 5-methylcytosine formation in DNA sequences differing in reassociation rate and susceptibility to DNase II digestion has been investigated in human chronic myelogenic leukemia and acute leukemia leukocytes, human PHA-stimulated lymphocytes and murine L5178Y lymphoblasts cultured in various phases of growth. The results indicate that in all forms of cells studied by us the general pattern of intragenomic 5-methylcytosine distribution is similar, with two preferentially methylated regions: the sequences fast reassociating and rendered Mg++-soluble after DNase II digestion of nuclei. The most variable fraction as regards the level of methylation seemed to be DNA of Mg++-soluble fraction of DNase II digest, which in acute leukemia leukocytes, PHA-stimulated lymphocytes and exponentially growing L5178Y cells revealed about twice greater relative proportion of methylated cytosines than in leukocytes of chronic myelogenic leukemia and L5178Y cells maintained at saturation density.

5-Methylcytosine↗
PubMed1980

The nucleolus in various phases of growth of mouse lymphoma L5178Y cells in culture.

The number of nucleoli in cultures of murine lymphoblasts L5178Y was investigated. It was found that during the cell cycle the number of nucleoli changed significantly. Comparison of the course of the cell cycle phases measured by the rate of 3H-thymidine incorporation into DNA and the mitotic index suggests that lymphoblasts containing 2 nucleoli are characteristic of the peak of the S-phase, lymphoblasts with 1 nucleolus--for the G1 phase or the border G1/S, lymphoblasts with 3 or more nucleoli--for the phase preceding mitosis, presumably late S and G2.

Animals↗
PubMed1979

Heterogeneity of DNA methylation in murine L5178Y lymphoblasts.

Comparison of the extent of methylation in mouse DNA fragments rendered MgCl2 soluble after mild DNase II digestion of nuclei, with different reassociation rate and nucleoli-bound, revealed the existence of 3 regions of the genome particularly 5-methylcytosine-rich: the sequences considered to be related to the transcriptionally active chromatin with the highest content of this base and fast reassociating, as well as nucleolar DNA with somewhat lower proportion of the methylated cytosines.

Animals↗
PubMed1979

Morphology of lysosomes in different phases of growth of lymphoblasts of L5178Y murine leukemia.

Parallel studies were carried out on the morphology of lysosomes, activity of DNA synthesis measured by the rate of 3 H-thymidine incorporation, and proliferative activity on the basis of values of the mitotic index of leukemia L5178Y lymphoblasts under varying growth conditions. Morphology of lysosomes was studied by the method of intravital staining with euchrysine. Observations were made on cells growing from the logarithmic phase to saturation density and synchronized by double blocking of DNA synthesis by hydroxyurea. The results showed some variation of the morphology of lysosomes related to growth phase of the cells.

Animals↗
PubMed1979

DNA methylation in various growth phases of cultured L5178Y murine lymphoblasts.

The extent of methylation of DNA during the transition of cells from exponential phase of growth to the saturation density has been studied in cultured L5178Y mouse lymphoma cells by the comparison of the degree of 5-methylcytosine formation and the stability of this preformed base in various periods of their growth. It has been found that while the degree of 5-methylcytosine formation gradually fell down, the level of this base preformed during the exponential growth was stable during the subsequent periods until the saturation density was reached. At that state some small and variable loss of the base was found.

Animals↗
PubMed1979

Differential cell-cycle-dependent inhibition of DNA synthesis by hydroxyurea and cytosine arabinoside in cultured L5178Y mouse lymphoma cells.

The effect of various concentrations of hydroxyurea and cytosine arabinoside on DNA synthesis, measured as 3H-thymidine incorporation, in exponentially growing and synchronized L5178Y cells in culture was investigated. The experiments revealed that each compound causes differential inhibition of DNA synthesis at various times of the S-phase. Maximum sensitivity to hydroxyurea occurred in cells in the late S, and maximum sensitivity to cytosine arabinoside in the early S-phase. When they were given simultaneously in low concentrations an additive effect was observed.

Animals↗
PubMed1978

Biofeedback-assisted EMG reduction and subsequent self-disclosure.

A male E and a female E each conducted a single session of EMG biofeedback training with 24 male and 24 female Ss (N =96) under one of three conditions: verbal reinforcement presented contingently on EMG reduction, yoked noncontingent verbal reinforcement, and no verbal reinforcement. After the biofeedback session, all Ss completed a Journard Self-disclosure Scale. Sex of S and verbal reinforcement conditions did not affect EMG biofeedback performance, but Ss treated by the male E decreased EMG mean and standard deviation more than Ss treated by the female E (p less than .01). Ss who received noncontingent verbal reinforcement reported being least willing to disclose to the E (p less than .05). These results are discussed in terms of the interpersonal influences that may affect biofeedback performance and self-disclosure.

Biofeedback, Psychology↗