[Comutagenic action of sodium selenite and caffeine on S. typhimurium TA 1535 with its subsequent treatment by N-nitrosomethylurea]. / Komutagennoe deistvie selenistokislogo natriia i kofeina na S. typhimurium TA 1535 pri ikh posleduiushchei obrabotke N-nitrozometilmochevinoi.

The comutagenic activity of sodium selenite and caffeine was studied by the Ames test. Reproduction of S. typhimurium TA1535 for 4 h at 37 degrees C in the nutrient broth with sodium selenide (5 micrograms/ml) significantly increased sensitivity of bacterial cells to the mutagenic action of 2-3 mM N-nitrosomethylurea (NMU). When using threshold concentrations of NMU the potentiation of mutagenesis reached 625.2%. The addition of 0.19 mg/ml of caffeine to the nutrient medium also led (though the action was less pronounced) to an increase in sensitivity of bacterial cells to the NMU mutagenic action. Reproduction of S. typhimurium TA1535 in the medium containing sodium selenide and caffeine did not cause an increase in the frequency of spontaneous his+-revertant mutations.

[The relationship between the activity of microsomal enzymes and pulmonary carcinogenesis in mice]. / Zavisimost' legochnogo kantserogeneza u myshei ot aktivnosti mikrosomal'nykh fermentov

Under study was the effect of phenobarbital, medinal and aminazine on the development of lung tumors in mice, as well as on the content of cytochrome P-450 in rat liver microsomes. Phenobarbital and medinal administration resulted in a 2-8 fold increase in cytochrome P-450 amount. Aminazine would reduce the latter but insignificantly. The number of urethan induced lung adenomas in mice was reduced by 64 per cent in phenobarbital exposure while medinal yielded only the decrease by 25-44 per cent. Aminazine failed to effect urethan carcinogenesis. Medinal would also suppress the development of DMBA induced lung tumors in mice by 34 per cent, but MC-by 50 per cent.

[Papillomas of the urinary bladder induced by N-nitroso-N-methylurea in rats]. / Papillomy mochevogo puzyria, indutsirovannye N-nitrozo-N-metilmochevinoi u krys

N-nitroso-N-methylurea (a total dosage--6 mg per animal), administered by a catheter in the urinary bladder cavity in female rats, following 9--56 weeks induced in 16 of 23 rats tumors of the vesical mucous membrane (mostly transitional cell papillomas).

[The relationship between stomach tumor development in mice and DMBA distribution]. / Zavisimost' vozniknoveniia opukholei zheludka u myshei ot raspredeleniia DMBA

The character of blastomogenic action of 7,12-dimethylbenz(a)anthracene on the stomach in its parenteral administration was studied on different lines of mice. Under the same conditions DMBA distribution was investigated in the proventriculus and gastric glandular tissues. In DMBA application on mice skin oin the dosage of 0.05 mg per animal in 0.1 ml of acetone proventricular tumors developed in 34% of mice of line CC57Br, in 10% of mice of line CC57W, and in 11% of mice of line C3HA, and in 19% of white nonpedigree mice. In intraperitoneal injection of DMBA in the dose of 0.5 mg per mouse in 0.2 ml of saline solution proventricular tumors appeared in 56% of CC57Br mice (in 9 of 16) and in one of five mice of CC57W line. Whereas, in application of DMBA onto mice skin in the dose of 0.5 mg per mouse in 0.1 ml of acetone the DMBA content in the proventriculus was 13 times higher than that in gastric glandular tissues.

[The effect of N-nitrosomethylurea on organ cultures of human embryonal lung tissue]. / Deístvie N-nitrozometilmocheviny na organye kul'tury émbrional'noí tkani cheloveka

The character of blastomogenic action of 7,12-dimethylbenz(a)anthracene on the stomach in its parenteral administration was studied on different lines of mice. Under the same conditions DMBA distribution was investigated in the proventriculus and gastric glandular tissues. In DMBA application on mice skin in the dosage of 0.5 mg per animal in 0.1 ml of acetone proventricular tumors developed in 34% of mice of line CC57Br, in 10% of mice of line CC57W, and in 11% of mice of line C3HA, and in 19% of white nonpedigree mice. In intraperitoneal injection of DMBA in the dose of 0.5 mg per mouse in 0.2 ml of saline solution proventricular tumors appeared in 56% of CC57Br mice (in 9 of 16) and in one of five mice of CC57W line. Whereas, in application of DMBA onto mice skin in the dose of 0.5 mg per mouse in 0.1 ml of acetone the DMBA content in the proventriculus was 13 times higher than that in gastric glandular tissues.

[Rat liver mitochondrial DNA treated with 1,2-dimethylhydrazine]. / Issledovanie mitokhondrial'noi DNK pecheni krys, obrabotannykh 1,2-dimetilgidrazinom.

Primary structure of 5'-end 16S RNA gene of mitochondrial DNA (mDNA) isolated from rat liver tissue within 20 hrs after treatment with 1,2-dimethyl hydrazine, was analyzed. The preparations studied did not contain mutations induced by the drug. The region of mDNA analyzed appears not to be a preferential target for mutagenic effect of 1,2-dimethyl hydrazine unber these experimental conditions.

[Induction of lung tumors in mice using diamylnitrosamine]. / Poluchenie opukholei legkikh u myshei s pomoshch'iu dismilnitrozamina

Mice of the CC57W strain were treated subcutaneouly with diamylnitrosoamine in a dose of 0.025 ml per mouse. once a week, 17 doses in all. These mice were sacrificed 27 weeks after the beginning of the experiment. Lung tumours, mainly adenomas, and in 3 cases adenocarcinomas, were detected in 14 of 17 mice which died and in 24 sacrificed mice. Besides, a marked proliferation of the interstitial tissue of the kidneys in a pretumor state, nephroblastoma, carcinoma in situ, and invasive cancer of the urinary bladder, one of each tumour, were found. Thus, diamylnitrosoamine can be recommended for induction of experimental lung tumours in mice.

[Antiradical activity and sulfhydryl group concentration in normal and tumor tissue]. / Issledovanie antiradikal'noi aktivnosti i kontsentratsii sul'fgidril'nykh grupp v normal'nykh i opukholevykh tkaniiakh.

In cytosol of normal and tumor tissues obtained from rats and hamsters, antiradical activity (ARA) of bioantioxidants was assayed by the method of Glavind, while the content of sulfhydryl groups by the method of Ellman. ARA of normal tissues (liver, kidneys, stomach, large intestine, femoral muscles) was lower than the content of free SH-groups. The difference between the magnitudes under consideration was always negative in all the test tissues. In tumors of the liver, stomach, kidneys, large intestine and femoral muscle induced in rats and hamsters by chemical carcinogens, there was an increase in ARA from 21 to 125.8% as compared with respective normal tissues. The difference between ARA and the content of SH-groups in the tumors was always positive. It might be assumed that in normal tissues, ARA is primarily determined by sulfhydryl compounds. Meanwhile, apart from SH-containing compounds, the other substances also take part in the control of ARA.

[Effect of the rhythm of administration of 1,2-dimethylhydrazine on its carcinogenic action]. / Vliianie ritma vvedeniia 1,2-dimetilgidrazina na ego kantserogennyi effekt.

The regimen of DMH treatment with the same total dose influenced the realization of its carcinogenic effect. The most extensive intestinal tumours were observed when DMH was administered once a week in a dose of 21 mg/kg of body weight. Daily treatment in a dose of 3 mg per kg results in development of a less marked malignant tumour process restricted to the colon alone. However, under such conditions the liver displayed marked dystrophic and necrobiotic lesions and occasionally tumours as well. Frequent entry of the carcinogen in small doses into the organism led to a significant decrease of cytochrome P450 content in the liver microsomes. This apparently slowed down the DMH metabolism, its conversion into the proximal metabolite and the binding of the latter to the macromolecules of enterocytes.