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Biomedical subjects

A I Medvedev

Publications and source records attributed to A I Medvedev.

At least 19 recordsLinked to original sources
PubMed2005

Apoptotic death of human lympholeukemia HL-60 cells resultant from combined effect of cobalt octa-4,5-carboxyphthalocyanine propylenglycol ether and ascorbate.

Cobalt octa-4,5-carboxyphthalocyanine propylenglycol ether proposed for antitumor therapy potentiates the cytotoxic effect of ascorbate on HL-60 human leukemia cells. Combination of these substances caused the formation of H2O2 in the medium and initiated apoptotic death of cells. Catalase abolished the cytotoxic effect of this combination. The results indicate that binary catalytic system of this combination can be regarded as a potential antitumor agent.

Antineoplastic Agents↗
PubMed2001

Combined treatment with vitamin B12b and ascorbic acid causes in vitro DNA degradation in tumor cells.

Incubation of Ehrlich ascites carcinoma and HEp-2 human epidermoid laryngeal carcinoma cells with hydroxycobalamin (vitamin B12b) and ascorbic acid induced generation and accumulation of double-stranded DNA fragments (23,000 b.p. and longer) in cells. The same vitamins alone in the same concentrations produced no such effects. DNA degradation in HEp-2 cells caused by long-term (4 h) incubation with 5-25 microM hydroxycobalamin and ascorbic acid (1:10-1:40 molar ratio) at 37 degrees C was comparable with that induced by gamma-irradiation in a dose of 150 Gy at 4 degrees C.

Ascorbic Acid↗
PubMed2001

[DNA degradation and repair in human laryngeal carcinoma HEp-2 cells after combined exposure to vitamin B12b and ascorbic acid].

The formation and accumulation of DNA fragments containing no more than 23,000 pairs of bases were observed under exposure of human larynx epidermoid carcinoma cells (Hep-2) to "chemical nuclease", oxycobalamin (vitamin B12b) and ascorbic acid (vitamin C). The obtained DNA damages were repaired more slowly than those induced by gamma-irradiation in the dose adequate to the level of DNA damages. DNA reparation was not revealed after washing the cells from vitamin B12b and ascorbic acid, and in the course of cell incubation with ascorbic acid. Vitamin B12b and ascorbic acid separately did not induce degradation of DNA. DNA damages induced by "chemical nuclease" action precede the cell death observed later.

Ascorbic Acid↗
PubMed1991

[The inhibition by strongly acidic polypeptides of the repair of double-stranded DNA breaks induced by the gamma irradiation of Chinese hamster fibroblast cells].

The ability of polypeptides consisted of aspartic and glutamic acids to inhibit the repair and to promote the formation of unrepaired double-strand DNA breaks and chromosomal aberrations in gamma-ray induced Chinese hamster cells was shown. A complete inhibition of the double-strand DNA breaks repair was observed at the concentrations of 20 mu M/l (polyglutamic acid with molecular weight 2000-15,000 daltons) and 100 mu M/l (aspartylglutamic acid with molecular weight 1500-4500 daltons). Both polypeptides were low toxic at the given concentrations.

Animals↗
PubMed1975

[Presence of biologically active glutamyl peptide in rabbit bone marrow].

The presence of chromatographically pure and biologically active glutamylpeptide in the rabbit bone marrow was shown and methods of its isolation were given. The substances had an unusual circular dichroism contrary to that of the natural proteins. In a concentration of 10(-5) M the isolated peptide decreased the survival of the Chinese hamster culture cells to 30%. It was analogous to the peptide isolated formerly from plants by a number of physical and chemical characteristics; the latter possessed cytogenetic activity and increased the mutagenic action of the ionizing radiation.

Animals↗
PubMedDate not supplied

[The effect of lead on DNA repair in thymocytes of gamma-irradiated mice].

The effects of Pb on the repair of DNA have been studied in the thymocytes of gamma-irradiated mice exposed to diacetate lead in the drinking water (up to 20 mg/l) for 14-50 days. It is found that lead causes no DNA degradation by itself and renders its genotoxic action indirectly, via inhibiting the repair of single-strand DNA breaks induced by acute gamma-irradiation of mice. Genotoxic effect of lead is reversible that becomes evident when exposed animals are maintained on Pb-free drinking water for 1-2 weeks.

Animals↗
PubMedDate not supplied

[The effect of gamma irradiation on the content in the thymus and liver chromatin of rats of DNA-bound proteins resistant to dissociation by phenol and sodium dodecylsulfate].

Two groups of proteins of 50-68 kD (A) and 12-14 kD (B) are the components of DNP preparations from rat thymus and liver obtained by washing with 0.075 M NaCl-0.024 M EDTA solution and deproteinization with phenol and dodecylsulfate (SDS). Immediately after irradiation with a dose of 10 Gy, there observed an approximately 1.5-fold increase in the content of only B proteins in the rat thymus fraction precipitated upon treatment with SDS-NaCl. The acidic amino acid content of this fraction and DNP preparation obtained without treatment with SDS amounts to 25 mol%; the ratio to basic amino acids was 1.3-1.4. The comparison of the amino acid content in the above DNP preparation and the "supramolecular DNA" preparation, described in the literature, that was obtained by the same phenol deproteinization and contained about 50 mol% of acidic amino acids, indicates the presence in the "supramolecular DNA" preparation of a component that increases upon irradiation: the component consists almost completely of acidic amino acids and is eliminated completely from the DNP preparation by washing with 0.075 M NaCl-0.024 M EDTA prior to deproteinization. The amino acid composition of the protein fraction A is presented.

Amino Acids↗
PubMedDate not supplied

[Acid polypeptides as intensifiers of the formation of irreparable double-stranded DNA breaks induced by the gamma irradiation of mammalian cells].

Acid polypeptides, synthetic analogues of a natural modifier of lethal effect of radiation, were shown to inhibit double-strand DNA breaks (DSB) repair, to increase irreparable DSB accumulation and to enhance the formation of structural chromosome rearrangements in gamma-irradiated mammalian cells. The authors discuss the possibility of involvement of proteins, that contain amino acid sequences comparable, in length, with a modifier, into radiation formation of irreparable DSB.

Animals↗
PubMedDate not supplied

[Stimulation of mitochondrial oxidative enzymes in acute cooling and its catecholamine mechanisms].

Acute cooling of rats led to stimulation of NAD+-dependent isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and NAD(P)+-transhydrogenase (TH) but did not affect the NADP+-ICDH activity in liver, heart and skeletal muscle mitochondria. After pretreatment of the animals with propranolol the stimulating effect was decreased, thus suggesting that endogenous catecholamines and beta-adrenoreceptors are of importance in activation of NAD+-ICDH, SDH and TH. The effects of cooling, noradrenaline and cAMP did not summarize. Role of catecholamines in stimulation of mitochondrial oxidative enzymes under conditions of cooling is discussed.

Animals↗