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Biomedical subjects

L V Kravchenko

Publications and source records attributed to L V Kravchenko.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

[Dietary protein as a modulator of the activity of enzymes metabolizing xenobiotics. Epoxide hydrolase].

Growing male rats received rations containing 5.18 and 33% of protein during 2 months. In contrast to other microsomal enzymes, epoxide hydrolase activity was maximal in the liver of the animals which received the ration with 5% of protein, and minimal--with 18% of protein. Epoxide hydrolase in the liver of rats that received the rations with 5 and 18% of protein showed equally expressed capacity for induction and activation in vivo and in vitro.

Animals↗
PubMedDate not supplied

[New data on the metabolism and physiologic mechanisms of aspartame action].

A comprehensive investigation of the physiological action of aspartame was conducted in 11 volunteers (healthy subjects, aged 18-37 years, with normal bw), and in experiments on 90 male Wistar rats, that were given aspartame in doses of 40 and 4000 mg/kg during 90 days, and in 3 dogs with gastric fistulas according to Basov. The study of microsomal and lysosomal activities in the liver, the turnover rate of liver proteins and blood plasma in rats revealed changes in the activity of liver cathepsins and in blood plasma albumin life time. The reaction of food thermogenesis after aspartame intake was recorded in experiments on dogs, that received sham feeding, and in the volunteers. As a whole, in the experiments including aspartame intake in a permissible daily dose for humans (40 mg/kg) no unfavourable action of the agent on the metabolic parameters studied was recorded.

Adolescent↗
PubMedDate not supplied

[Effect of mycotoxins aflatoxin B1 and T-2 toxin on the vitamin D3 metabolism and binding of its hormonal form 1,25-dihydroxyvitamin D3 in rats].

Effects of aflatoxin B1 and T-2 toxin, administered daily within 7 days at the doses of 0.7 mg/kg and 0.54 mg/kg, respectively, on metabolism of Ca and on the vitamin D hormonal system were studied in young rats kept on a ration containing normal (0.025 mg/kg) and high (0.25 mg/kg) amounts of vitamin D. Administration of the mycotoxins caused hypocalcemia, a decrease in absorption of Ca as well as in activity of alkaline phosphatase in small intestine mucose, while alterations in spongy bones (of the type of osteopetrosis) were most distinct in T-2 toxin treatment. Concentration of 25(OH)D3 in blood serum and activity of 25-hydroxylase D3 in liver tissue were decreased by 28% and 58%, respectively, after administration of T-2 toxin, and by 34% nd 33%, respectively, after treatment with aflatoxin B1. In kidney activity of I-hydroxylase 25(OH)D3 was unaltered and the activity of 24-hydroxylase tended to decrease. After treatment with the mycotoxins content of nuclear receptors of 1,25(OH)2D3 was decreased in small intestine mucose, whereas cytoplasmic receptors were increased 2.5-fold, thus indicating the distinct decrease in the receptors internalization. High doses of vitamin D caused an increase of Ca content in blood serum and of its absorption in small intestine as well as normalized Ca content in cortical bone of rats treated with T-2 toxin. At the same time, activity of 1-hydroxylase 26(OH)D3 was increased in liver tissue, while concentration of 1,25(OH)2D3 receptors was reduced in small intestine, but internalization of the hormone receptors was maintained at low level.(ABSTRACT TRUNCATED AT 250 WORDS)

Aflatoxin B1↗
PubMedDate not supplied

[Enzyme parameters in the evaluation of the combined effects of protein deficiency and T-2 mycotoxin].

Male Wistar rats received a low-protein (4.5% protein) diet during 30 days, and T-2-toxin was administered to them through a gastric tube, in a dose of 0.54 mg/kg, during 15 days. The results obtained showed activation of hepatic lysosomal enzymes (sulfatase A and B aryl and beta-glucosidase) and alkaline phosphatase, and to an essential suppression of enzymatic activity of peroxisomes - catalase, glycolate oxidase and D-amino acid oxidase. A sharp aggravation of the intoxication symptoms and pronounced intensification of changes in enzymatic activity in the liver, spleen, thymus and blood serum were recorded in the animals given T-2 toxin simultaneously with the low-protein diet.

Acetylglucosaminidase↗
PubMedDate not supplied

[Comparative characteristics of microsomal epoxide hydrolase in the rat liver and small intestine mucosa].

Activity of epoxide hydrolase was studied in microsomes of rat liver and small intestinal mucosa with styrene oxide as substrate using high performance liquid chromatography. Specific activity of epoxide hydrolase in microsomes from small intestine constituted 5-10% of the activity in liver microsomes. Both these enzymes had similar kinetic parameters, the same pH optimum around pH 8.7; their activity was altered only slightly in presence of anionic detergents. The enzyme activity was increased in liver and small intestine after administration of benzyl, trans-stilbene oxide, 2-acetamidofluorene and butylated hydroxytoluene. 1,2-epoxy-3,3,3-trichloropropane and 2-brom-4-nitroacetophenon inhibited similarly epoxide hydrolase in hepatic and intestinal microsomes. Cyclohexene oxide inhibited both these enzymes by the non-competitive type, exhibiting the higher affinity to liver epoxide hydrolase.

Animals↗
PubMedDate not supplied

[Activity of enzymes of xenobiotic metabolism in the liver of rats with vitamin A deficiency and mycotoxicosis T-2].

Keeping male rats within a month on a ration deficient in vitamin A led to a distinct decrease in content of cytochrome P-450, in activities of carboxylase, epoxide hydrolase, aniline hydrolase and to a slight inhibition of UDP-glucuronosyl transferase in live tissue. At the same time, activity of glutathione transferase and content of reduced glutathione in liver tissue were increased. After administration of the epoxide-containing T-2 mycotoxin into rats within 10 days at a dose of 0.54 mg/kg activity of the enzymes catalyzing metabolism of xenobiotics was inhibited in the animals maintained on the complete half-synthetic ration, except of epoxide hydrolase and glutathione transferase, activity of which was elevated. The administration of T-2 toxin under conditions of deficiency in vitamin A caused especially distinct inhibition of the enzymes involved in the 1 phase of xenobiotic metabolism but it was accompanied by only slight increase in T-2 toxicosis. The enzymes participating in conjugation of xenobiotics as well as epoxide hydrolase appear to play major roles in detoxication of T-2 mycotoxin.

Animals↗
PubMedDate not supplied

[Effect of different supplies of vitamin E on biochemical changes in T-2 mycotoxicosis in rats].

Maintainance of rats within 3 months on a ration with low content of vitamin E (6 mg/kg as compared with 100 mg/kg in control) did not alter distinctly the enzymatic activity in mitochondria, lysosomes and the activity of the enzymes, metabolizing xenobiotics as well as did not affect the permeability of lysosomal and plasmatic membranes. In subacute T-2 mycotoxicosis of rats kept on control ration the following alterations were noted: decrease in activity of lysosomal enzymes, aniline hydroxylase, carboxyl esterase and in content of cytochrome P-450 in liver tissue simultaneously with two-fold activation of epoxide hydrolase and UDP-glucuronosyl transferase; decrease in non-sedimented activity of lysosomal enzymes; decrease in activity of alkaline phosphatase and of lysosomal enzymes in blood serum. After administration of the toxin into vitamin E deficient rats, its effect was increased, hemorrhagic syndrome was distinctly developed, permeability of lysosomal and plasmatic membranes was increased. Subnormal consumption of vitamin E appears to cause destabilization of biological membranes structure, which is manifested under conditions of stress.

Animals↗
PubMedDate not supplied

[Spectrofluorimetric method of determining epoxide hydrolase].

A spectrofluorometric procedure is developed for estimation of epoxide hydrolase activity using styrol oxide as a substrate. The data were plotted, reflecting the dependence of the enzymatic reaction on time, pH value and the substrate concentration. Activity of epoxide hydrolase was studied in various tissues and subcellular fractions of rat liver tissue.

Animals↗
PubMedDate not supplied

[Biochemical, hematological and immunological criteria for assessing chronic T-2 mycotoxicosis in mice].

The authors studied the effect of a long-term intragastric administration to CBA X C57Bl/6 male mice of T-2 toxin in doses of 0.067 mg/kg bw a day (1/100 of the LD50) or 0.33 and 0.45 mg/kg a day (1/20 and 1/15 of the LD50) on the liver content of protein, cytochrome P-450 SH-glutathione and on the activity of 10 lysosomal and microsomal enzymes and glutathione transferase. A dose-dependent increase in the activity of lysosomal hydrolases and glutathione transferase localized in cytosol was revealed together with a fall in the activity of microsomal aniline hydroxylase, carboxyl esterase and epoxide hydrolase. Emphasis is laid on a dose-dependent reduction in the liver of nonsedimented activity of lysosomal enzymes. In T-2 mycotoxicosis, the most sensitive and the most stable parameter was the activity of lysosomal enzymes in blood serum. That activity also declined during the recovery period, namely 3 months after discontinuance of toxin administration. Both groups of mice showed a progressive decrease in the blood leukocyte count and lysozyme content, whereas in the spleen, there was a decrease in the number of antibody-forming cells. It is concluded that biochemical, hematological and hematological characteristics should be taken into consideration in evaluating the chronic action of T-2 toxin.

Animals↗
PubMedDate not supplied

[Organization of the system of control of food contamination with mycotoxins].

Mycotoxins are secondary metabolites of microscopic fungi. They are classified with particularly hazardous contaminants of foods and feeds. It has been demonstrated that they are extremely dangerous for the health of man, widely spread and do considerable economic damage. The authors describe in detail the data as to the level of contamination of different foods with aflatoxins, ochertoxins, citrinin, patulin, trichotecenic mycotoxins, and zearalenone. The principal role in the prevention of human mycotoxicoses is played by the control over food contamination with mycotoxins. An organization program of the control has been developed. The principal feature of the program is the organization of the specialized scientific-practical centers responsible for the collection and summarization of the results of monitoring and for the development of prophylactic measures. The authors provide data on the maximum allowable concentrations of aflatoxins in foods validated in different countries. Review the topics concerned with the assessment of the efficacy of the control over food contamination with mycotoxins.

Aflatoxins↗
PubMedDate not supplied

[Effect of T-2 toxin on the activity of organelle-specific enzymes of various rat organs].

Dynamics of 5 marker enzymes activity from subcellular particles--succinate dehydrogenase, beta-glucosidase, arylsulphatases A and B, acid RNAase and glucose-6-phosphatase--were studied in liver, spleen, thymus and blood serum of rats after single intragastric administration of T-2 toxin at a dose of 3.8 mg/kg (LD50). The acute intoxication was accompanied by an early (within 1-3 hrs) and significant reduction of total proteins in the tissues studied. Distinct tissue- and organelle-tropic effects of T-2 toxin were found: the toxin induced a gradual decrease in activity of the enzymes studied in liver tissue, while selective activation of lysosomal hydrolases was observed in spleen and thymus tissues. The selective effect of T-2 toxin on spleen and thymus lysosomal hydrolases appear to be involved in the mechanism of action of the toxin.

Animals↗
PubMedDate not supplied

[Enzyme characteristics of food poisoning caused by grain contaminated with Fusarium sporotrichiella].

Subacute experiments were made to examine the effect of the grain contaminated with Fusarium sporotrichiella on the activity of organelle-specific enzymes of the liver, thymus, spleen, bone marrow and blood serum of rats (beta-N-acetylglucosaminidase, alpha-mannosidase, beta-galactosidase, arylsulfatases A and B, succinate dehydrogenase, glucose-6-phosphatase, alkaline phosphatase, ketoso-1-phosphate aldolase) and on the protein content. The feeding of the grain provoked an early appearance of the symptoms of intoxication and a change in the activity of organelle-specific enzymes manifesting in the activation of lysosomal hydrolases in the thymus, bone marrow and spleen and in a decrease in the blood serum activity of the most enzymes investigated.

Acetylglucosaminidase↗