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Biomedical subjects

A Ia Litoshenko

Publications and source records attributed to A Ia Litoshenko.

At least 19 recordsLinked to original sources
PubMed1990

[Structural-functional characteristics of chromatin fractions in the regenerating liver of adult and old rats].

The transcriptional activity, nucleosomal patterns, and thermodenaturation parameters of low-active and active fractions of liver chromatin were studied in adult (6-8 mo) and old (26-28 mo) rats at 2, 4, and 6 weeks after partial hepatectomy. At 2 weeks postoperatively, there was a decrease in relative specific radioactivity (RSR) of the active chromatin fraction in adult rats, which returned to normal by the 4th week, while in the low-active fraction it was decreased throughout all the studied regeneration periods. The decrease of the low-active fraction RSR was attended with changes in the nucleosomal organization and DNA-protein interactions revealed by electrophoresis and thermodenaturation. Old rats were found to have the active fraction RSR unchanged throughout all the studied regeneration periods. The low-active fraction RSR increased at 2 and 4 postoperative weeks and decreased to the level of intact liver at 6 weeks. Electrophoretic analysis and parameters of thermodenaturation of the low-active fraction reflect changes in the chromatin conformation associated with transcription activation and, at the same time, reveal its higher compactness in nucleosomal structures. Age differences in the time-course of structural rearrangements and transcriptional activity of liver chromatin during regeneration may be responsible for different rates of postoperative liver restoration in adult and old rats.

Age Factors↗
PubMed1989

[Age-related characteristics of RNA transport through the nuclear membrane].

The effect of cytosol and ATP-regenerating system on RNA, transport was studied in isolated liver nuclei of adult and old rats. The stimulating effect of cytosol was found not to depend on the age of animals. The release of RNA from old rat liver nuclei activated by the ATP-regenerating system was more expressed compared to adult rats. It is assumed that the age changes of energy-delivering system of the RNA transport through nuclear membrane may be conditioned by the deficit of endogenous energetic substrates in the hepatic cells of old animals.

Adenosine Triphosphate↗
PubMed1989

[Lipid peroxidation and the endogenous DNA polymerase activity of fractions of isolated liver chromatin in rats].

Lipids which enter the composition of actively transcribed and repressed chromatin fractions are found to undergo a peroxidation. The peroxidation induction results in a depression of the endogenous DNA polymerase activity of these fractions. Tetrachloromethane increases the intensity of lipid peroxidation processes and induces a more marked depression of the DNA polymerase activity in all repressed chromatin fractions. It is assumed that selective action of tetrachloromethane on the studied indices of this chromatin fraction may be related to the differences of lipid composition of actively transcribed and repressed chromatin.

Animals↗
PubMed1989

[Lipid peroxidation and the polymerase activities of liver chromatin fractions in rats during aging].

Lipids, which enter the composition of actively transcribed and repressed chromatin fractions are found to undergo a peroxidation. This process decreased with aging and more pronounced in actively transcribed chromatin fraction. A decreased activity of DNA polymerase beta and increased activity of RNA polymerase I in this chromatin fraction with aging were observed. It is assumed that observed changes of genome function of old animals may be caused by decreased peroxidation of chromatin lipids.

Aging↗
PubMed1986

[Effect of ethanol on the DNA-polymerase activity in the liver subcellular fractions of adult and old rats].

The effect of 5% ethanol on DNA polymerase activity in nuclei, mitochondria, microsomes and cytosol of intact and regenerating liver of adult and old rats has been studied. No changes in DNA polymerase activity were detected in subcellular fractions of adult rat liver. On the contrary, the increased activity of intact liver nuclei and decreased activity of regenerating liver microsomes was observed with ageing. These age-dependent peculiarities of DNA polymerase activity in response to 5% ethanol may be related to changes in the enzyme molecules or microenvironment associated with ageing.

Aging↗
PubMed1984

[Renewal of mitochondrial DNA in the liver of rats of different ages].

The rate of mitochondrial DNA turnover was studied in the liver of adult and old rats. It was shown to decrease with aging in both the whole mitochondrial population and its heavy and light fractions. This decrease reflects the deceleration of the rate of liver mitochondrial biogenesis in old age and is considered to be a cause of energy deficiency of an old body.

Aging↗
PubMedDate not supplied

[Molecular mechanisms of damage to fractionated liver chromatin by tetrachloromethane].

Impairing effects of tetrachloromethane on genetic apparatus were shown to consist in its high affinity and binding to transcriptionally active fraction of chromatin and subsequent destruction of DNA. As a result of the impairment the density of the chromatin fraction was increased which expressed as elevated stability to hydrolysis by endogenous nucleases. At the same time, content of single-stranded structures enriched with proteins was increased in the DNA of the transcriptionally active fraction of chromatin. Two dissimilar properties were detected in the fraction of impaired chromatin from the poisoned animals: increase of density in the chromatin fraction accompanied by insensitivity to S1-nuclease, which was detected after denaturation of chromatin and slight relaxation of apparently supernucleosome structures where content of sites, sensitive to short-term treatment with DNAase I, was increased. The hypothesis of the tetrachloromethane toxic effect on genetic apparatus is considered, according to which lipid moiety of chromatin and activation of lipid peroxidation are of definite importance in effects of the xenobiotic on chromatin.

Animals↗
PubMedDate not supplied

[Effect of emotional-pain stress on RNA and protein synthesis in rats of different age].

The intensity of RNA and protein biosynthesis is studied in different tissues as well as in active and low-active fractions of liver chromatin, when adult and old rats are subjected to emotional-painful stress during 3 days. Significant stimulation of RNA and protein biosynthesis in chromatin fractions in liver and total RNA and protein in adrenals and hypothalamus is observed.

Age Factors↗
PubMedDate not supplied

[Changes in protein, lipid composition, DNA- and RNA- polymerase activity of the chromatin fraction and the nuclear matrix of the rat liver in hypovitaminosis E].

E-hypovitaminosis-induced antioxidant deficiency in rats causes changes in some properties of nuclear structures of the liver cells, i.e. fractions of transcriptionally active and repressed chromatin and nuclear matrix. Changes are found in the protein spectrum of the fraction of transcriptionally active chromatin and nuclear matrix. Lipids of transcriptionally active and repressed chromatin fractions may be peroxidated when this process is stimulated in the NADPH- and ascorbate-dependent systems. In antioxidant deficiency these processes are intensified in the fractions of repressed chromatin. E-hypovitaminosis leads to changes in the fatty acid spectrum of chromatin fractions which correlated with the shifts in the process of lipid peroxidation. Antioxidant deficiency produces changes in the activities of endogenous DNA- and RNA-polymerases in chromatin fractions and in the nuclear matrix. In the fraction of the transcriptionally active liver chromatin of E-deficient animals the endogenous total DNA-polymerase activity and the activity of DNA-polymerases alpha and beta decrease, while in the fractions of repressed chromatin the total RNA-polymerase activity increases. In E-hypovitaminosis the endogenous DNA- and RNA-polymerase activities in the nuclear matrix decrease. Addition of alpha-tocopherol to the preparations of the isolated nuclear matrix results in an increase of the DNA- and RNA-polymerase activities which is more vivid in preparations made of the E-hypovitaminous animal liver.

Animals↗
PubMedDate not supplied

[Lipid peroxidation and parameters of thermodenaturation of chromatin fractions in the rat liver].

The fractions of transcriptionally active and repressed chromatin of the rat liver include lipids, whose fatty acid residues are the substrates of lipid peroxidation (LP) processes. In vitro incubation in NADPH- and ascorbate-dependent LP systems resulted in the activation of peroxidation in the liver chromatin of intact animals, estimated from malonic dialdehyde (MDA) accumulation, the LP processes proceeding more intensely in the fractions of transcriptionally active vs. repressed chromatin. This correlates with the content of LP substrates in these fractions. Single administration of tetrachloromethane stimulated LP (estimated from the content of diene conjugates) in the fraction of transcriptionally active chromatin. The intensity of MDA accumulation increased in the repressed chromatin fraction of animals with stimulated LP vs. the control. In animals with stimulated LP the changes in the thermodenaturation parameters of chromatin fractions were observed, being more expressed in the transcriptionally active fraction. In view of the temporal coincidence of the LP intensification in chromatin and of its structural-functional reconstruction, the alteration of intensity of LP processes in chromatin may be considered as a factor of regulation of functional activity of the genome.

Animals↗
PubMedDate not supplied

[Functional activity of fractionated chromatin from rat liver upon a single administration of carbon tetrachloride].

Functions of rat liver cell genome were distinctly altered after a single administration of tetrachloromethane into animals. Maximal alterations in the structure-functional properties of chromatin were detected within 2 hrs after intoxication. The phenomenon was accompanied by the following shifts in the chromatin active fractions: activation of DNA- and RNA polymerases, decrease in content of this fraction, increase in the ratio protein/DNA due to elevation in the protein component with molecular mass 65 kDa detected in the nonhistone fraction of electrophoretogram. Alterations in the repressed chromatin fraction were less distinct. Many parameters of the chromatin fractions were normalized within 24 hrs after the intoxication. Peroxidation of lipids contained in chromatin occurred via NADPH-and ascorbate-dependent reactions, the rate of which was distinctly higher in the repressed chromatin fraction of liver cells from the animals intoxicated within 24 hrs. These alterations in the structure-functional properties of liver chromatin fractions, developed after a single administration of tetrachloromethane into animals, were related neither to the rate of lipid peroxidation in chromatin, stimulated by tetrachloromethane, nor to alterations in Ca2+ and Mg2+ content in nuclear fraction. cAMP-dependent phosphorylation of chromatin proteins appears to be rather responsible for chemical impairments of hepatocyte membranes stimulated by tetrachloromethane.

Animals↗
PubMedDate not supplied

[Age-dependent changes in the DNA-polymerase activity of nuclei and mitochondria of the regenerating rat liver].

The DNA polymerase activity in nuclei and mitochondria of adult and old rat liver was determined. No age-dependent changes in the DNA polymerase activity have been found in the intact rat liver. On the contrary, after partial hepatectomy the DNA polymerase activity was higher in nuclei of the adult rat liver and in mitochondria of the old one. These peculiarities of the DNA polymerase activity with ageing may depend on changes in molecular properties of DNA polymerases, their synthesis and intracellular concentration.

Aging↗