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T S Shuliakovskaia

Publications and source records attributed to T S Shuliakovskaia.

At least 19 recordsLinked to original sources
PubMed1989

[The role of UDP glucuronosyl- and sulfotransferases in the butylhydroxytoluene suppression of the mutagenic action of carcinogenic nitroso compounds and cyclophosphane].

Treatment with butylated hydroxytoluene (BHT) was shown to stimulate the activity of UDP-glucuronosyltransferase and to inhibit that of sulfotransferase in liver of Wistar male rats. Addition of UDP-glucuronic acid to incubation medium in Ames' test using BHT-pretreated subfractions of rat liver resulted in decreased mutagenicity of nitrosodiethylamine, nitrosomorpholine and cyclophosphamide. Further treatment with 3'-phosphoadenosine-5'-phosphosulfate failed to affect mutagenic activity of the promutagens tested. However, an increase in mutagenicity of nitrosomorpholine and cyclophosphamide was observed in application of liver subfractions from intact animals. It was concluded that BHT-induced inhibition of active metabolite production as well as increased production of their glucuronides are responsible for inhibition of mutagenicity of the agents tested. Simultaneous decrease in the yield of sulfates potentiated this effect for nitrosomorpholine and cyclophosphamide.

Animals↗
PubMed1988

[Modifying effect of antioxidants on the rate of lipid peroxidation in liver microsomes at early stages of diethylnitrosamine biotransformation].

Lipid peroxidation and free radicals' generation were investigated in rats treated with carcinogenic diethylnitrosamine (DENA) after pretreatment with some antioxidants. It was shown that decreased generation of free radicals during DENA metabolism in rat liver microsomes after pretreatment of animals with antioxidants may be the cause of the protective action of these antioxidants against DENA toxicity. Lipid peroxidation was shown to be not a crucial reaction in the toxic effect of DENA.

Animals↗
PubMed1988

[Effect of modifiers of microsomal enzymes on the enzymatic denitrosation of dialkyl-N-nitrosamines].

The antioxidant butyl-hydroxytoluene has been shown to increase denitrosation of some dialkyl-N-nitrosamines by the liver microsomes of different lines of rats and to protect against diethyl-N-nitrosamine toxicity. 3-Methylcholanthrene, while decreasing denitrosation of diethyl-N-nitrosamine, increased its toxic effect. This data suggested that enzymatic denitrosation is an effective pathway for the inactivation of dialkyl-N-nitrosamines.

Animals↗
PubMed1987

[Butylhydroxytoluene inhibition of the mutagenic activity of carcinogenic nitroso compounds and cyclophosphamide: the role of the glutathione conjugation reaction].

Mutagenic effect of diethylnitrosamine, nitrosomorpholine and cyclophosphamide were studied on Salmonella typhimurium in the Ames test using S9, microsomal and cytosolic subfractions of Wistar male rats. Pretreatment with butylhydroxytoluene (BHT) was followed by a 50-60% decrease in metabolic activation of the said promutagens by liver subfractions. This was matched by an increase in cytosolic and microsomal glutathione-S-transferase activity and glutathione level in rat liver. The addition of glutathione to the incubation medium in the Ames test using liver subfractions of BHT-treated rats brought on a complete inhibition of mutagenic effect of the agents studied. It is suggested that BHT-induced decrease in production of active metabolites and increase in their inactivation in reactions of glutathione enzymatic conjugation account for the inhibition of mutagenicity of the promutagens under study.

Animals↗
PubMed1987

[Effect of modifiers of the cytochrome P-450-dependent enzyme system of the liver on the metabolic pathways of diethylnitrosamine activation and inactivation].

Pretreatment of Wistar male rats with antioxidants prevented the toxic effect of diethylnitrosamine (DENA) at LD50. Six-fold acceleration of DENA excretion and significant increase of maximum plasma concentration of a DENA metabolite nitrite were, also observed after antioxidants treatment. Liver microsomal metabolism of DNA was altered by pretreatment with another antioxidant--butylhydroxytoluene, which stimulated selectively denitrosation and inhibited dealkylation of DENA in the microsomal cytochrome P-450-dependent enzyme system. Moreover, butylhydroxytoluene treatment diminished he ability of microsomes to activate DENA to mutagenic intermediates identified in Ames' test. It was suggested that the protective effect of antioxidants against DENA toxicity may be due to the acceleration of its metabolic inactivation and the inhibition of its activation in liver cytochrome P-450-dependent systems.

Animals↗
PubMed1987

[Additional pathway of the metabolic activation of N-nitrosodiethylamine in the rat liver].

A cytosolic enzyme, aldehyde oxidase (AO), was shown to be involved in metabolic activation of carcinogenic diethylamine (DENA). DENA was reduced to corresponding hydrazines by AO in the presence of benzaldehyde. Products of DENA reduction by AO possessed mutagenic activity for Salmonella typhimurium TA 1950. Pretreatment of rats by antioxidant butylhydroxytoluene had no effect on this process of DNA bioactivation.

Aldehyde Oxidase↗
PubMed1986

[Study of promutagen biotransformation in the Ames test. III. The role of conjugation with glucuronic acid and sulfate in the modification of mutagenic effect of nitrosomorpholine, diethylnitrosamine and cyclophosphamide].

The role of reactions of conjugation with uridine diphosphoglucuronic acid (UDPGA) and with 3-phosphoadenosine-5-phosphosulfate (PAPS) in modification of the mutagenic effect of diethyl nitrosamine (DENA), nitrosomorpholine (NM) and cyclophosphane (CP) was studied by the Ames test. It was shown that adding UDPGA to the activating mixture significantly decreased the level of the mutagenic effect of DENA, NM and CP on bacteria Salmonella typhimurium TA 1950, when S9 and microsomal fractions of rat liver homogenate were used. Adding PAPS to the activating mixture when S9 and cytosole fractions were used, did not affect mutagenic action of DENA on S. typhimurium TA 1950 and TA 1535, enhancing the mutagenic effect of CP on TA 1535, with no such influence on TA 1950. Introduction of PAPS into the activating mixture elevated the mutagenic effect of NM on both bacterial strains using S9 fraction but not cytosole fraction.

Animals↗
PubMedDate not supplied

[Computer simulation of ESR signals of liver paramagnetic centers].

Changes of paramagnetic centres concentration characterized by g-factors values of 1.94, 2.2, and 2.03 in the rat liver were studied by ESR method under acute intoxication by diethylnitrosamine (DENA) and at preliminary threefold treatment of animals with butylhydroxytoluene (BHT). A protective effect of BHT can be explained by its stabilizing action of the membrane structures. A comparison has been carried out with a similar study of paramagnetic centres in the experiment of chronic intoxication by DENA. A simulation was performed of the liver tissue ESR spectra by means of special computer program. The parameters of simulated ESR spectra of the liver tissue with due regard for ESR signal g 2.03 corresponded to the parameters of the experimental spectra. Confirmations were obtained for the nature and number of paramagnetic centres in the liver tissue.

Animals↗
PubMedDate not supplied

[Effect of antioxidants on the activity of liver glutathione-S-, glucuronyl- and sulfurtransferases in rats].

It was shown that pretreatment of rats with antioxidants (AO) butylhydroxytoluene and 2-ethyl-6-methyl-3-hydroxypyridine hydrochloride owing to its effect of animal protection against intoxication with diethylnitrosamine (DENA) increases the liver activity of enzymes of stage II metabolism of xenobiotics: glutathione-S-transferase (GST), UDP-glucuronyltransferase (UDP-GT). Administration of DENA (LD50) produced a significant decrease of the activity of GST and UDP-GT as compared with that in intact animals. At the same time its action on the animals pretreated with AO develops against the background of increased activity of these enzymes.

Animals↗