[Cytochrome p450 system components and nitric oxide synthase activity in mouse liver under conditions of retinoid stores absence].

p-Hydroxylase and N-demethylase activities of cytochrome P450 system, NO-synthase activity and the intensity of nitric oxide and superoxide anion production in mitochondrial, postmicrosomal and microsomal cellular fractions were studied in mouse liver under conditions of retinoid stores absence. It is determined, that under conditions of retinoid stores absence the activation of NO-synthase is occurring with decreasedp-hydroxylase activity of cytochrome P450 system. The results of the generation intensity analysis showed the level of NO and O(2-) in liver mitochondrial fraction of knock-out mice, and changes in NADPH-dependent O(2-) production in microsomal fraction of mouse liver cells.

[The induction of Guerin's carcinoma cytochrome p450 hydroxylase activity by retinoids].

The interconnection of tumor growth process and the provision of the body with vitamin A was studied. The replenishment of vitamin A stores of vitamin-deficient tumor bearing animals modulated Guerin's carcinoma growth rate in a dose dependent manner (r = 0,83). The morphological parameters of tumor growth at different provision with vitamin A positively correlated with hydroxylase (r = 0,81) and demethylase (r = 0,49) activities of the Guerin's carcinoma cytochrome P450 system. The induction of hydroxylase and demethylase activities of cytochrome P450 in Guerin's carcinoma microsomal fraction, observed either under conditions of overdose supplementation, or selective liposomal form of all-trans-retinoic acid, suggests the stimulatory effect of retinoids on tumor growth.

[Xanthine oxidase activity in transplantable Guerin's carcinoma in rats].

Influence of low-dosage pre-irradiation on xanthine oxidase levels in Guerin's carcinoma was studied with particular emphasis on free oxygen generation and free sulphohydrils in a fraction of proteins characterized by xanthine oxidase activity. Enhanced growth of tumor correlated with that of xanthine oxidase activity involving higher levels of enzymatic O-form due to thiol groups oxidation. Under similar conditions, xanthine oxidase and free oxygen generation levels were higher due to SH-group oxidation than in intact animals. Terminal stages involved dropping xanthine oxidase levels and enzymatic protein degradation.

[Effect of vitamin A provision on antineoplastic resistance in rats].

While studying Guerin's carcinoma development under conditions of different vitamin A provision in the period of tumor growth and before it appearance, it was established, that strengthened saturation of an organism with a tumor by vitamin A hyper doses can both stimulate and inhibit tumor progression. The effect depends on duration of vitamin A administration and on the level of preliminary provision of an organism with this vitamin. The hyper doses administration for 7 days on the normal vitamin A provision background and the normal doses administration to vitamin A-deficient animals which is especially expressed antitumor effect. The continuation of hyper doses administration to 14 days leads to rising of tumor sizes, especially expressed in vitamin A-deficient animals.

[Effect of preliminary irradiation on DNA-ase activity and DNA fragmentation degree in the nuclei of Guerin's carcinoma cells].

The effect of preliminary irradiation on DNA-ase activity and DNA fragmentation degree in the nuclei of Guerin's carcinoma was evaluated. It was found that effective growth of malignant cells involved higher concentrations of acid DNA-ase matched by decreased levels of alkaline one which in turn lowered the rates of DNA fragmentation. Low-dose preliminary irradiation stimulated relevant processes.

[Effect of tumor growth and preliminary irradiation on the state of DNA degradation processes in the liver cell nuclei].

This study is devoted to the analysis of DNase activity and DNA fragmentation level in liver cells nuclei of rats with transplanted Guerin's carcinoma on irradiation background. Was shown, that in an organism of previously irradiated rat with tumor the dominance of neoplasm development over the consequences of the irradiation is observed on the initial stages of the experiment. The alignment of gamma-irradiation influencing already takes place from the first stages after Guerin's carcinoma transplantation, which is testified by the decrease of DNase activity of liver cells nuclei and the decrease of a degree of nuclear DNA fragmentation. On the stationary stages of tumor growth the general action of the factors causes differences in the parameters of the investigated animal groups. It shows that together with the constant reduced level of DNase activity the processes of DNA fragmentation strengthen and their intensity reaches maximum during this period. The nature of the fragmented DNA accumulation is similar to the irradiated organism on the first days after the radiation factor removal. Thus, the radiation-induced signal in the organism with tumor is leveled under the conditions of active neoplasm growth; nevertheless, the consequents of its operating do not disappear, and only move away in time.