PubMed Health⌕ Search

Biomedical subjects

G N Bogdanov

Publications and source records attributed to G N Bogdanov.

At least 19 recordsLinked to original sources
PubMed1996

Membranotropic properties of the water soluble amino acid and peptide derivatives of fullerene C60.

The modifying effects of the products of the equimolar addition Of DL-alanine and DL-alanyl-DL-alanine to fullerene C60 on the structure and permeability of the lipid bilayer of phosphatidylcholine liposomes has been studied using the luminescence probe technique. It is shown that these water soluble amino acid and dipeptide derivatives of fullerene (C60-AD) are quenchers of pyrene fluorescence and erythrosine phosphorescence of in both a water solution and liposomes. To study the permeability of the lipid bilayer a procedure based on the triplet probe technique has been developed. It has been found that the C60-AD derivatives under study are able to localize inside the artificial membrane, to penetrate into the liposomes through the lipid bilayer and to perform activated transmembrane transport of bivalent metal ions.

Alanine↗
PubMed1987

[Protective action of an antioxidant of the 3-hydroxypyridine class on the contractility and electrogenesis of the heart muscle in hypoxia and reoxygenation].

The effect of SD-6, a 3-hydroxypyridine antioxidant, on the pattern of variation in contraction intensity, contracture and membrane potentials were assessed in experimental studies on isolated left ventricular papillary muscles of rats, exposed to hypoxia and reoxygenation. The antioxidant considerably limited hypoxic and reperfusion contracture, its efficiency increasing with a concentration reduced to 10(-7) g/ml. Contraction intensity and duration of action potentials, diminished by hypoxia, were only recovered by reoxygenation, if the antioxidant was present. It is assumed that the recovery of action potentials by reoxygenation in the presence of SD-6 may result from normalization of ATP-dependent outgoing current through the kappa channels, activated by ATP deficiency. The antioxidant capacity for levelling diverse durations of action potentials between normal and ischemic areas is evidence of an important contribution of free-radical mechanisms to the development of reoxidation-induced recirculation arrhythmias.

Animals↗
PubMed1986

[Correlation of the activity of the key enzymes of glycolysis and respiration in hepatomas with different growth rates].

It is shown that an increase in the activity of glycolysis resulting from the rise of the hepatoma growth rate is accompanied by a decrease in the activity of the pentose-phosphate pathway and respiratory chain. It is supposed that variations in the activity both of different carbohydrate catabolism ways and the respiration with a rise of the hepatoma growth rate reflect changes in the relative content of cells at different phases of the cell cycle.

Animals↗
PubMed1984

[Oxidation of anthracycline antibiotics].

The quantum-chemical estimation of the highest occupied molecular orbital energy for the aglycons of carminomycin, rubomycin, adriamycin and aclacinomycin A in the neutral and ionized states was performed with a semiempirical method. It was shown that the aglycon ionization amplified the electron donor properties of the antibiotics. On the basis of the difference in the absorption spectra of the neutral and ionized chromophores their ionization constants were determined spectrophotometrically. For comparison of the electron donor properties of the anthracyclines at the physiological pH value the reaction of their oxidation with potassium ferricyanide accompanied by decoloration of the solutions was studied. On the basis of the quantum-chemical and experimental data it was concluded that the electron donor properties amplified as follows: aclacinomycin A less than adriamycin-rubomycin less than carminomycin. At the same time their acute toxicity increased (a decrease in the LD50). Therefore, the toxicity of the anthracycline antibiotics could be also due to formation of the radicals with high reactivity on the monoelectronic oxidation.

Antibiotics, Antineoplastic↗
PubMed1983

[Free radical mechanism of action of pyrimido-triazine antibiotics].

EPR spectra of anion radicals were recorded as a result of chemical or enzymatic reduction at various pH of the pyrimido-triazine antibiotics. These anion radicals easily form superoxide radicals in the presence of oxygen. It is supposed that a higher selectivity of reumycin action is due to difference in the redox potentials of the neutral and ionized antibiotic forms. A possibility of enhance the reumycin potency may involve the pH lowering inside the tumor cells - for example, by glucose injections.

Animals↗
PubMed1981

[Transformation and the kinetic cell growth patterns in vitro after exposure to adenovirus SV20 DNA].

Malignant transformation of the normal rat embryo cells has been obtained by monkey adenovirus SV-20 and its DNA. The appearance of the transformed colonies with a multi-layer cell growth was observed at the 28th day. The influence of the growth medium pH on the process of cell transformation has been studied. The kinetic regularities of normal and transformed cells growth were investigated by a cloning assay.

Adenoviridae↗
PubMed1980

[Biochemical and cytokinetic patterns in the growth of a transplanted pigmented melanoma].

Under study were biochemical and cytokinetic patterns of the pigmented melanoma growth in mice. The data obtained allows a conclusion that there is a relationship between the process of melanogenesis and proliferative activity of the tumor tissue. A delayed tumor growth beyond the peak point due to the reduced proliferative pool and increased cell losses is accompanied with a fall in the activity of the key enzyme of melanogenesis and the reduced level of melanoproteids.

Animals↗
PubMed1978

[Investigation of tyrosinase activity and phospholipid composition in Harding-Passey melanoma microsomal fraction].

Alteration in DOPA-oxidase activity of Harding-Passey melanoma microsomal fraction tyrosinase, activation of tyrosinase after partial delipidization of the microsome, phospholipid composition of both native microsomes and the ones after delipidization have been studied. In the course of tumor growth (starting on the 14th day after tumor transplantation) the tyrosinase activity has been shown to decrease monotonously both in native microsomes and in the ones after delipidization. The phospholipid composition alters both in the process of tumor growth and after delipidization. Alteration in the tyrosinase activity in native microsomes as well as after their delipidization has been found to depend on the relative composition of certain phospholipids. In those cases a linear correlation between the enzyme activity and the phosphatydylethanolamine of phosphatydylcholine ratio has been found. This interrelationship may be accounted for by either simultenous presence of inhibitors and activators of the enzyme activity in the lipids or by changes in the membrane structure depending on the relative phospholipid composition.

Animals↗
PubMed1975

[Metabolism of nucleic acids in normal, regenerating and neoplastic tissues of the liver].

Under study was the kinetic growth of three hepatomas-22A, 60 and 46, characterized by a various degree of differentiation. There was found a correlation between the degree of differentiation and parameters of the hepatomas growth. For the hepatomas a correlation between the DNA content and rate of growth was observed, for hepatoma 46 a value of the DNA content proved to be near to that of normal liver. Moreover, in a regenerating liver the DNA content is the same as normal, that indicates the difference between normal and neoplastic actively proliferating tissues. The processes of DNA synthesis, studied by thymidine-C14 incorporation, showed a linear correlation with the rate of growth in regenerating, normal and neoplastic tissues. The ratio RNA/DNA in tumors is regularly decreased with respect to normal liver (a linear correlation between RNA/DNA and the maximum rate of growth). In a regenerating liver the ratio is high. Variations in the ratio RNA/DNA reflect changes in the functional activity and related disorders in the metabolism of nucleic acids in hepatomas. There was found a suppressed DNA decomposition in autolysis of homogenates from hepatoma tissues. It is essential to note that in a minimum deviated hepatoma some inhibition of the DNA decomposition is the only observed disorder in the nucleic acids metabolism. Spin-labelled DNA preparations of tissues under study were obtained. The presence of structural differences between separate DNA samples has been demonstrated.

Animals↗