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Biomedical subjects

V V Vinogradov

Publications and source records attributed to V V Vinogradov.

At least 19 recordsLinked to original sources
PubMed2002

[Use of ascorbic acid for raising clinical response to long-acting nitrates].

The data of clinic observation and ECG-monitoring show that ascorbic acid significantly increases antianginal vasodilatory effects of nitroglycerine thus preventing from development of ischemic miocardial reaction in response to complamin injection. Incubation under anaerobe conditions of ascorbic acid solution with NO-donors (sodium nitrate, nitroglycerine) or with the blood of ischemic patients who had been treated for a long time with long-acting nitrovasodilators, results in liberation in Varburg vasculium of gas bubbles identified as nitrogen oxide according to hemoglobin nitrosylation. Activation of endogen NO-donors with ascorbic acid and taking antilogs of antianginal effects of exogenous nitroglycerine makes it possible to substantially increase the efficiency of nitratotherapy and nitratoprophylaxis of angina pectoris.

Adult↗
PubMed2001

[Effect of cultivation conditions on the functional activity of thyrocytes in the organ culture of the thyroid gland in newborn piglets].

In new-born piglets' thyroid gland culture, thyrocytes were capable of synthesising thyroxine and triiodothyronine for over 12 days. A 48-hour decline of the medium pH to 6.45 did not affect further functional activity of the cells. Decrease in temperature to 26-28 degrees C augmented the thyroid hormones level as opposed to continuous cultivation at 37 degrees C. Degradation of the thyroid gland follicular structure induced a change in the hormones biosynthesis. The thyrocytes not arranged in the follicles mainly produced triiodothyronine in concentrations 5 to 8-fold higher than the T4 contents.

Animals↗
PubMed1999

Reduction of nitrite by glycosylated amino acids and glycosylated albumin.

Glycosylated amino acids and glycosylated human serum albumin reduce nitrite to nitric oxide under anaerobic conditions. The amount of nitric oxide produced was recorded by generation of nitrosoHb from deoxyHb. Without preincubation after the addition of sodium nitrite, glucose or a mixture of glucose with amino acid or serum albumin did not cause spectrophotometrically detectible transformation of deoxyHb into nitrosoHb. The generation of NO increased with an increase in content of colored "final" products of amino acid and serum albumin glycosylation in the incubation mixture. The incubation of blood plasma of patients with diabetes mellitus with nitrite also resulted in the increased production of NO as compared to blood plasma of healthy subjects. During the incubation of healthy subjects' blood plasma with nitrite a small amount of NO was produced. The removal of low-molecular-weight compounds was accompanied by a significantly decreased generation of NO by blood plasma.

Adult↗
PubMed1997

Concept of the noncoenzymatic thiamine effect.

The experimental and clinical data on different aspects of vitamin and hormone relationships have been summarized in the form of a general concept of the noncoenzymatic thiamine effect, on the basis of a number of premises: (1) discovery of tissue factors limiting the manifestation of the specific activity of administered thiamine (the presence of a tissue buffer depot of easily accessible coenzymes, and lack of free apoenzymes); (2) evidence of a thiamine effect on the pancreatic insulin-synthesizing function; (3) stimulation of metabolic thiamine effects, including the effects of insulin administration on thiamine-dependent enzymes; (4) determination of the features of hormonal control of thiamine metabolism in the body; (5) confirmation of the predictive force of the concept by clinical trials of the new strategy of thiamine therapy.

Animals↗
PubMed1997

Reduction of methemoglobin and ferricytochrome c by glycosylated amino acids and albumin.

The fraction of Amadori products gradually decreased during heavy glycosylation of amino acids and human serum albumin while the amount of a colored product with the maximum fluorescence at 420 nm decreased. The addition of the produced ketoamines of amino acids to the solution of native albumin quenched its own fluorescence due to generation of a Schiff base with amino groups of the protein. Carbonyl-containing Amadori products obtained during the early steps of glycosylation were less potent electron donors than amino acids more heavily modified by the carbohydrate. Under anaerobic conditions, glycosylated amino acids and human serum albumin reduced metHb and ferricytochrome c to ferroforms. In the presence of oxygen, the electron was transferred from glycosylated amino acids to ferriforms of the heme proteins and also to oxygen molecules with the generation of superoxide anions and hydrogen peroxide. Free oxygen radicals and hydrogen peroxide induced damage to the protein globule of Hb associated with the release of hemin, Fe(III) ions, and cleavage of the porphyrin ring.

Amino Acids↗
PubMed1995

[Is oxythiamine an antivitamin?].

The review deals with biological and medical aspects of oxythiamine biochemistry with special reference to the facts which contradict the traditional antivitamin conception. Alternatives to the coenzyme mechanism in interpreting the metabolic effects of this vitamin B1 derivative are discussed.

Animals↗
PubMed1992

[Inhibition of pyruvate kinase of bovine adrenal cortex by ATP: the role of magnesium].

The effect of ATP on bovine adrenal cortex pyruvate kinase has been studied. ATP is a competitive inhibitor of the enzyme, the Ki being 3.2 mM. Based on the efficiency of tryptophan fluorescence quenching, it was concluded that the magnesium complex of ATP is a true enzyme inhibitor. The role of Mg2+ in the inhibition process consists in the formation of a bridge between the enzyme and ATP. The ATP-dependent mechanism of pyruvate kinase inhibition is a potential physiological regulator of the enzyme determining the lower threshold of its sensitivity in vivo.

Adenosine Triphosphate↗
PubMed1991

Thiamine cardiotropism.

Thiamine administration (200 mg/kg 2 hours before start of the experiment) substantially reduced the myocardial ischaemic lesion in a model of experimental myocardial infarction in the rat. As shown by stereometric analysis of histological heart preparations, the cytoprotective action of vitamin B1 is mediated by increased cardiomyocyte resistance towards ischaemia, i.e., through an adequate increase in the relative volume of the protection zone. Experiments on a model of emotional-painful stress in the rat show that the antiischaemic action of vitamin B1 cannot be explained by a specific cardiotropism of thiamine (the presence of thiamine phosphate buffer depots excludes the manifestation of coenzymatic effects of thiamine under given conditions) but by an antistressor action of thiamine resulting in exclusion of an important pathogenetic link in the mechanism of stress-conditioned cardiopathy.

Animals↗
PubMed1990

[Study of pH-dependence of kinetic parameters of pyruvate kinase from bovine adrenal cortex].

The effect of pH on the main kinetic parameters of pyruvate kinase function was studied. The maximal rate of the reaction as well as the values of Km for ADP and Ki for phenylalanine depend on pH and show a well-defined extremum at pH 6.8-7.0. Spectrofluorimetric titration of pyruvate kinase results in pH dependencies of changes in the fluorescence spectra parameters (e.g., quantum yield, half-width and position of the maximum). This enabled to determine the pH regions corresponding to changes in the state of tryptophan residues. Data from the enzyme inhibition by phenylalanine suggest that acidification of the medium leads to the decrease of the catalytic activity due to the protonation of the ionogenic group of the enzyme. Within the pH range of 7.0-8.0, the decrease of the pyruvate kinase activity is due to structural shifts in the enzyme molecule, as a result of which the steric complementariness of the enzyme active center with respect to the substrate (Mg.ADP) is impaired.

Adrenal Cortex↗
PubMed1990

[Lipid peroxidation in the adrenal cortex during exhausting stress].

Under prolonged stress which is connected with exhaustion of functional resources of adrenal cortex the activation of lipid peroxidation processes in this gland was found. It is possible that the reason for such lipid peroxidation activation is the decrease in the content of adrenal cortex ascorbic acid and alpha-tocopherol.

11-Hydroxycorticosteroids↗
PubMed1988

[Kinetic model of the functioning of pyruvate kinase from bovine adrenal cortex].

The dependence of pyruvate kinase reaction rate on the concentration of one of the ligands--ADP or MgCl2--at constant concentrations of the other ligand was studied. The enzyme activity vs ligand concentration curves have fairly symmetrical peaks which correspond to the range of approximately equal ligand concentrations. The S-shaped dependence is observed only over the range of concentrations close to the dissociation constant for the Mg-ADP- complex (0.7 mM) under the given experimental conditions. The data obtained are consistent with the results of the first model kinetics within the framework of the London-Steck theory. The substrate for pyruvate kinase is the Mg-ADP- complex, while free Mg2+ and ADP3- competitively inhibit the enzyme. The inhibition constants are equal to 44 and 1 mM, respectively. The inhibiting effects of the metal and dinucleotide may be due to the competition with the substrate for the enzyme active site. Taking into consideration the fact that the binding of one of the ligands to the enzyme depends on the presence of the other ligand, a conclusion is drawn that Mg2+ forms a bridge with ADP3- and pyruvate kinase from adrenal cortex.

Adrenal Cortex↗
PubMed1987

[Kinetic properties of NADP-specific isocitrate dehydrogenase from bovine adrenals].

At low concentrations of Mg2+ or Mn2+ the reaction catalyzed by isocitrate dehydrogenase from bovine adrenal cortex proceeds with a lag period which disappears as a result of the enzyme saturation with Mn2+ or Mg2+. The nu o versus D,L-isocitrate concentration curve is non-hyperbolic, which may be interpreted either by the presence of two active sites with different affinity for the substrate (K'mapp = 2.3 and 63 microM) within the enzyme molecule or by the "negative" cooperativity of these sites. The apparent Km value for NADP lies within the range of 3.6-9 microM. High concentrations of NADP inhibit isocitrate dehydrogenase (Ki = 1.3 mM). NADP.H inhibits the enzyme in a mixed manner with respect to NADP (Ki = 0.32 mM). In the presence of NADP.H the curve nu o dependence on NADP concentration shows a "negative" cooperativity between NADP binding sites. The reverse enzyme-catalyzed reaction of reductive carboxylation of 2-oxoglutarate does not exhibit any significant deviations from the Michaelis-Menten kinetics. The Km value for 2-oxoglutarate is 120 microM, while that for NADP.H is 10 microM.

Adrenal Glands↗