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M N Medvedeva

Publications and source records attributed to M N Medvedeva.

At least 19 recordsLinked to original sources
PubMed1990

Age-related changes of the H1 and H1(0) histone variants in murine tissues.

The relative proportion of the histone H1(0) which is present in chromatin of nondividing and terminally differentiated cells is shown to increase with age. CNBr nonenzymatic cleavage and SDS-polyacrylamide gel electrophoresis of H1(0) extracted from liver chromatin of young and old mice and from age-related hepatocarcinomas showed that H1(0) consists of two variants, one contains methionine the other is methionine-free. The ratio between these two H1(0) variants also changes with age. The relative amounts of specific minor H1 and H1(0) histone fractions which are more loosely bound in chromatin and are extractable with 0.35 M NaCl, together with the HMG nonhistone proteins decrease in ageing mouse tissues. The age-related alteration of the ratio between H1(0) variants probably represents the chromatin repair process, whereas the age-related replacement of H1A and H1B subfractions by H1(0) histones may reflect the continuing process of differentiation.

Aging↗
PubMed1988

Age related variations of hepatocarcinogenic effect of azo dye (3'-MDAB) as linked to the level of hepatocyte polyploidization.

Four-week-old CBA mice fed a diet containing the hepatocarcinogenic azo dye 3'-MDAB showed a rapid polyploidization of hepatocytes, a sharp increase of two liver-specific acid soluble non-histone proteins (LSP 1 and 2) and induction of hepatomas between 44 and 52 weeks of the regimen. More mature 18-week-old mice fed the same diet did not develop induced hepatocarcinogenesis after 55 weeks of the regimen. Interruption of the azo dye regimen showed that the increase of LSP 1 and 2 was reversible, whereas the carcinogenic effect and polyploidization were irreversible. Sprague-Dawley rats were more sensitive to the carcinogenic effect of the azo dye regimen. It is suggested that the higher resistance of older mice to the carcinogenic effect could be linked to the higher level of hepatocyte polyploidization and that the increase of LSP 1 and 2 is relevant to the toxic effect of the azo dye.

Aging↗
PubMed1984

Age-related changes of the pattern of non-histone proteins in active and condensed fractions of mouse liver chromatin and hepatocarcinoma.

Electrophoretic analysis of histones and non-histone acid-soluble proteins in active (nuclease sensitive) and inactive chromatin from liver of young and old CBA mice and in age-related hepatocarcinomas showed a higher ratio of NHP:histones in active chromatin in old cells. Some liver- and hepatoma-specific fractions of non-histone proteins have been identified as chromatin matrix proteins.

Aging↗
PubMed1982

The characterization of non-histone proteins whose amounts increase in chromatin from mouse hepatocarcinomas.

A fraction containing liver- and hepatoma-specific non-histone proteins has been isolated from the chromatin of mice. Amino acid analysis of this fraction shows that it contains 16 mol of glutamic acid, 10 mol aspartic acid, 7 mol of both arginine and lysine per 100 mol and contains no cysteine or tyrosine. The proteins in this fraction are strongly associated with DNA and are co-extracted with histones from chromatin with 0.25 M HCl. In chromatin from age-related hepatomas, the amount of this fraction increased six-fold. This increase in concentrations of these chromatin proteins may be associated with changes of chromatin structure necessary to initiate malignant growth in liver cells.

Amino Acids↗
PubMed1980

Characteristics of the ribonucleoprotein of influenza virus A.

Ribonucleoproteins (RNP) of influenza viruses A/Singapore/1/57, A/Victoria/35/72 and those isolated in the course of passaging in persistent infection systems (influenza virus--diploid human lung cells) were subjected to desimentation analysis. In viruses of different antigenic structure the 3 RNP fragments had the same sedimentation coefficients (63, 53, and 42 S, respectively). The ratios of RNP fragment concentrations had an individual character and were in relation with the antigenic differences between the strains studied.

Animals↗
PubMed1979

Age-related changes of the pattern of non-histone chromatin proteins from rat and mouse liver chromatin.

The non-histone chromatin (NHC) proteins which are loosely bound to DNA were extracted from young and old mouse and rat liver chromatin by 0.35 M NaCl and fractionated into three groups: water-soluble, 0.14 M NaCl soluble and 0.35 M NaCl soluble. NHC proteins in each fraction were separated by SDS-disc polyacrylamide gel electrophoresis. Special attempts were made to locate minor high-molecular-weight proteins which develop faint bands. It was found that the aging of liver cells is associated with increase in number and quantities of high-molecular-weight NHC proteins in the water-soluble group. Salt-soluble groups of NHC proteins show fewer changes of pattern.

Aging↗
PubMed1978

Tissue specificity and age changes for the pattern of the H1 group of histones in chromatin from mouse tissues.

Polyacrylamide gel electrophoresis of the H1 group of histones extracted from different rat and mouse tissues shows a different pattern of fraction (H1, H1 degrees, H1 degrees met) when the two species are compared. Different tissues of each species also have a different pattern of H1 histone fraction and subfraction. However, the age-associated changes of mouse H1 histones from liver and spleen chromatin show the same type of alteration of fraction ratios which had been demonstrated in our earlier research with rat tissues. In both species there is a relative increase of the F1 degree and F1 degree met fractions in tissues from old animals. The presence of the F1 degree fraction in only non-dividing cells suggests that there may be an age-specific type of chromatin condensation.

Aging↗
PubMed1978

Experimental investigation of changes in the antigenic structure of influenza viruses during their persistence.

Systems of persistent influenza infection produced in the cultures of human embryonal kidneys and in the diploid cells of human embryonal lungs under the effect of A/Hong-Kong/1/68 and A/Victoria/35/72 viruses were characterized. The cell systems were studied in the course of 4--3u passages, i. e., from 40 to 289 days. A total of 102 viruses were isolated during the period of observation, out of which 44 were examined for the antigenic profile of HA and NA. The antigenic structure of the initial viruses was preserved in 31 variations isolated while in 13 variants it was pronouncedly and permanently changed. The following mechanisms of the mentioned phenomenon are discussed: mutations, intrapopulation recombinations and integrations.

Antigens, Viral↗
PubMed1977

Age changes of the pattern of F1 histone subfractions in rat liver and spleen chromatin.

The polyacrylamide gel electrophoresis of total histone extracted from young (3 months) and old (26-27 months) rat tissues does not show age-related differences in the pattern of the main five histones. However, when the lysine-rich F1 histone was extracted from chromatin separately by perchloric acid and purified by Biogel P-60 column chromatography from chromatin of rat liver and spleen, the polyacrylamide gel electrophoresis did show obvious age changes in the distribution of F1, F1o, and F1(00) subfractions. In liver chromatin the increase of rat-specific methionine-containing subfraction (F1met.) was also found.

Aging↗
PubMed1976

[The transforming activity of influenza virus in tissue cultures].

First, it was shown that one can model chronic influenza infection induced by influenza virus A (Honkong) 1/68 and A (Victoria) 35/72 in a primary culture of human kidney (PHK). The persistance of the mentioned viruses in PHK and diploid cells of human lungs (DCHL) is associated with a cytoproliferative effect, manifested in the enhancement of mitotic and proliferative activity of the cultures, in prolongation of "the life" of the primary persistantly infected PHK culture for 60-100 days, as compared with the control. During passages epithelial cells were replaced by fibroblast ones, these were readily transplanted later. No transformation effect due to the action of influenza virus in cell cultures, chronically infected, was noted.

Cell Line↗