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Biomedical subjects

V V Adler

Publications and source records attributed to V V Adler.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Possible reasons for decrease in the proliferating activity of the rat thymus after a single injection of glucocorticoids].

A single injection of triamcinolone-acetonide evoked multiple changes in adrenectomized rat thymuses, e.g. decrease of DNA polymerase and thymidine kinase activities, incorporation of [3H]thymidine into DNA and fragmentation of chromatin. The decrease of proliferating activity of thymus was preceded by inactivation of cytoplasmic DNA polymerase responsible for DNA replication. Fragmentation of DNA caused by double strand ruptures at the linkage sites affected primarily the non-proliferating thymocytes. Incubation of nuclei isolated from the thymuses of control and hormone-treated animals in Ca2+ and Mg2+-containing media increased the level of low molecular weight compounds in them. It was assumed that the inhibiting action of triamcinolone-acetonide on cytoplasmic DNA polymerase prevents the involvement of proliferating thymocyte subpopulation in a new generation cycle and provides for their terminal differentiation and decay, eventually resulting in fragmentation of DNA.

Adrenalectomy↗
PubMed1982

[Binding of glucocorticoid-receptor complexes with the acceptor zones of nuclei and effect of glucocorticoids on RNA synthesis in hormone-sensitive and hormone-resistant cell populations].

The binding of free radioactive glucocorticoid and the glucocorticoid-receptor complex to rat liver nuclei was studied in vitro. The binding is non-saturated and independent of preliminary injection of the "cold" hormone. In the course of DNA hydrolysis the amount of the radioactive hormone bound to the chromatin moiety in vivo remains practically unchanged relatively to the initial radioactivity of the protein. The liberation of the nuclei into a cell-free medium and the effect of DNAase I on the nuclei are associated with the redistribution of the hormone-receptor complex in the chromatin molecule and with the appearance of new, previously masked acceptor zones of the hormone binding. During the first 1-2 hours following the hormone injection the endogenous RNA-synthesizing activity of the nuclei is decreased. The increase of RNA synthesis in liver nuclei occurs not earlier than 3 hours after the injection. In Zajdela hepatoma nuclei the repression of RNA synthesis persists as long as 3 hours after the injection of dexamethasone. When RNA synthesis is determined in the nuclei in the presence of exogenous RNA-polymerase of E. coli in vitro, the increase in nuclear RNA synthesis can be observed beginning with the 30th min after the hormone injection. It is assumed that this effect is due to conformational changes in the chromatin structure, which are concomitant with the initial steps of association of the hormone-receptor complex.

Animals↗
PubMed1982

[Early changes in template DNA structure following glucocorticoid injection].

The structure of chromatin is changed at early stages of glucocorticoid hormone interaction with rat hepatocytes. These changes consist in: a) increase of actidine orange binding in rate liver nuclei after injection of the hormone; b) decrease of the number of sites in chromatin which are sensitive to nuclease S1; c) inhibition of the nuclei capacity for DNA synthesis in the presence of E. coli DNA polymerase and d) increase of molecular weight of DNA fragments. The data obtained suggest that at early stages of hormonal induction part of template DNA ruptures is reconstituted, which can result in an increase of DNA molecular weights and changes in chromatin superstructure and the template properties of the protein.

Animals↗
PubMed1982

[Effects on the process of DNA transcription in vitro of formaldehyde and the products of its reaction with amines].

When transcription of DNA treated with aminomethylol compounds (products of formaldehyde reaction with amines) was studied, aminomethylol produced a marked inhibition of the template activity of double-stranded DNA (up to 85%). Formaldehyde suppressed the transcription of native DNA as well, however, only when taken at concentrations exceeding those of the aminomethylol compounds 20-fold.

Amines↗
PubMed1981

[Sensitivity of intranuclear glucocorticoid complex from normal rat liver and Zajdela ascites hepatoma to ionic strength and nuclease treatment].

After 30 min of intraperitoneal injection of dexamethasone to adrenectomized rats about 15% of the label are incorporated into liver homogenate and only 1% of the cytosol-bound hormone is detected in the cell nuclei. The binding of the "in vitro" injected hormone by the nuclei does not obey the second-order reactions (the Scatchard plots). This is probably due to the existence of various ancillary mechanisms, which control the translocation of the hormone complex into cell nuclei at the level of cytoplasm and nuclear membranes. DNAase I, micrococcal nuclease and endogenous nucleolysis markedly increase the part of the nuclear hormone complex resistant to 0.4 M NaCl. In hepatocyte nuclei obtained by the collagenase method, the content of the 0.4 M NaCl-resistant receptor complex is also increased. The resistance of 0.4 M NaCl was also found in 80% of the glucocorticoid-insensitive nuclear complex from Zajdela ascite hepatoma cells. The changes in interaction of the hormone-receptor complex with nuclear acceptor sites eventually resulting in impaired sensitivity of host tissues to hormonal control can be due to the damage of chromatin structure induced by different influences and tumour growth.

Animals↗
PubMed1980

[Role of plasma membranes in the glucocorticoid transfer into target cells].

The [3H]hydrocortisone transfer into intact target cells and into non-target cells, e. g. isolated hepatocytes, hormone-sensitive Morris hepatoma 7777 cells, hormone-resistant Zajdela ascite hepatoma cells, was studied. In target cells the glucocorticoid transfer is temperature-dependent, i. e. the curve for hormone binding by the cells at increasing concentrations shows a plateau Phospholipase A2 and neuraminidase decrease the ability of the cells to incorporate the labelled hormone. The experimental data differ significantly from those obtained for target cell cytosol and for intact Zajdela hepatoma cells. It was assumed that in target cells the crucial role in hormone transfer into the cells belongs to plasma membranes, while in non-target cells the hormone penetrates inside the cells by passive diffusion.

Animals↗
PubMed1979

[Interaction between the dexamethasone-receptor complex and Zajdela ascites hepatoma DNA].

The activated dexamethasone--receptor complex from rat liver cell cytoplasm and from Zajdela ascite hepatoma cell cytoplasm is bound to Sepharose-immobilized native DNA containing different numbers of recurrent sequences. The DNA-bound hormonereceptor complex is eluted as three peaks by varying concentrations of NaCl. The binding in independent of the number of DNA recurrent sequences and of the source of the cytoplasmic complex used.

Animals↗
PubMed1979

[Liver reactivity to glucocorticoids in the process of chemical hepatic carcinogenesis].

The rat hepatocytes during chemical carcinogenesis (3'-MDAB), as well as the cells of chemically-induced primary rat hepatomas preserved their response to partial hepatectomy by stimulation of the 3H-thymidine incorporation into DNA; as in the normal liver this process is inhibited by dexamethason. No impairment in the inducibility of tyrosine aminotranspherase (EC.2.6.1.5) by the hormone was observed, whereas the hormonal induction of tryptophane pyrrolase (EC.1.13.11.11) in primary hepatomas was lost completely. The problem of the adequacy of the model of chemical carcinogenesis of the organ without consideration of the cell populations heterogeneity is discussed.

Animals↗
PubMed1979

[Existence of glucocorticoid-specific receptors in the plasma membranes of rat liver].

It was found that isolated plasma membranes whose purity was assayed by determinations of marker enzyme activities, specifically bind dexamethasone. The association constant and the number of binding sites were found to be equal to (7,03 +/- 4,05) . 10(9) M-1 and (1,6 +/- 0,18) . 10(-14) mol/mg protein, respectively. It was assumed that lipoprotein components of plasma membranes are involved in this binding.

Animals↗
PubMed1978

[Reaction between dexamethasone-receptor complexes and isolated nuclei from Zajdela hepatoma and rat liver cells].

Temperature-activation of the hormone-receptor complex (HRC) was shown to be necessary to ensure its translocation from cytoplasm to nucleus both in the rat liver and hepatoma. Hepatoma nuclei bind 20 times less HRC derived from homologous hepatoma cytosol (0.15 pmol/mg DNA), but twice as much (5.6 pmol/mg DNA) of HRC from heterologous liver cytosol, as compared with the binding of HRC from normal liver cytosol by liver nuclei (3 pmol/mg DNA), Ka of HRC with the acceptor sites in hepatoma and liver nuclei were found to be practically of the same order of magnitude. The above findings suggest an inhibition of cytosol-nucleus translocation of HRC from the cytosol of hepatoma cells as a possible cause of the nonresponsiveness of the latter to the hormone.

Animals↗
PubMed1977

[Sensitivity of the lymphocyte RNA-synthesizing system of patients with different malignant neoplasms to phytohemagglutinin and dexamethasone].

RNA biosynthesis catalyzed with DNA-dependent RNA polymerase was demonstrated in the reconstructed system containing isolated lymphocyte nuclei, Mg2+ or Mn2+ salts, ammonium sulphate, in the presence of four nucleosidetriphosphates. Both the Mg2+ and Mn2+-dependent forms of this enzyme were revealed in the nuclei of normal lymphocytes and those of patients suffering from melanoma, carcinoma of the lung and sarcoma. The activities of both forms of RNA-polymerase were greater in the nuclei of the lymphocytes from sick individuals than in the normal analogues. DNA-dependent RNA-polymerase sensitivity to dexamethasone and PHA of the nuclei of lymphocytes obtained from patients with carcinoma of the lung, melanoma, and sarcoma was decreased in comparison with the normal.

DNA-Directed RNA Polymerases↗
PubMed1976

[Comparative characteristics of cytosol glucocorticoid receptors from normal liver, the liver of tumor-bearing rats and hormone unresponsive Zajdela hepatoma].

Specific dexametasone (D) and cortisol (F) receptors have been found both in liver and Zajdela hepatoma. Rat liver cytosol receptors are characterized by the association constant (Kas) = 3,8 X 10(8) M-1 for D and 0,57 X 10(8) M-1 for F as well as by a number of binding sites (NBS)=4,9 X 10(-13) moles/mg protein and 4,06 X 10(-13) moles/mg protein, respectively. The receptors show stric specificity to glucocorticoids. Cytosol glucocorticoid-receptor complexes from liver and hepatoma sediment at 6-7S, when centrifuged in the buffer of a low ionic strength, and at 3-4S in the buffer of a high ionic strength (0,4 M KCl). The properties of cytosol receptors in the course of in vivo hepatoma growth were found to be gradually altering: Kas for D dropped whereas that for F increased; the NBS is decreased 3-4 fold as compared to normal liver cytosol--which may partially be accounted for by the unresponsiveness of the tumour to the hormones.

Animals↗
PubMed1976

[Changes in the matrix properties of chromatin during aminoazocarcinogenesis].

Male rats were on a diet containing 3-methyl-4-dimethylaminoazobenzol, a carcinogen. There were found no changes either in the electrophoretic total spectrum of deoxyribonucleoprotein (DNP) or in nonhistone proteins; the character of DNA and DNP melting curves or the matrix capacity of DNA extracted from the rat liver also remained unchanged. DNP of the tumour tissue acted more actively in the capacity of the matrix for the RNA synthesis in vitro in the system with the animal or bacterial RNA-polymerase with low substrate concentrations (2-10-5 M); but with high concentrations of each one of the substrates (2-10-3 M) RNA synthesis was the same as in control. With nuclear lysis in the solution with alkaline pH the percentage of RNA-polymerase activity, which it was possible to extract from the complex with chromatin, decreased considerably in rats given carcinogen.

Animals↗