[Effect of different doses of ascorbic acid on the induction of tumors with N-nitroso compound precursors in mice]. / Vliianie razlichnykh doz askorbinovoi kisloty na induktsiiu opukholei u myshei predshestvennikami N-nitrozosoedinenii.

Experiments used 409 male CBA mice to study the effect of ascorbic acid on carcinogenesis induced by treatment with such precursors of nitroso compounds as sodium nitrite and morpholine. The former was given with feed in a total dose of 573-891 mg/animal and the latter--with drinking water in a total dose of 138-183 mg/animal. As a result, the total number of tumor-bearers grew from 63.8% (controls) to 82.5%. Treatment with all doses of ascorbic acid tested (1.5; 0.25 and 0.025% with drinking water) was followed by reduction in frequency of tumors in animals treated with nitroso compound precursors to 37.9, 55.1 and 60%, respectively.

[Carcinogenic hazard of small doses of nitrite in connection with the endogenous synthesis of nitroso compounds]. / Kantserogennaia opasnost' malykh doz nitrita v sviazi s éndogennym sintezom nitrozosoedinenii.

Carcinogenic risk of small doses of precursors of nitroso compounds, i.e. sodium nitrite (total dose in 0.2-2.0 g/mouse in drinking water) and morpholine (total dose is 0.23 g/mouse in bread) was studied in 520 CBA and 290 C57Bl mice during 96 weeks. It is shown that under these conditions the carcinogenic effect was more pronounced in CBA mice: there was a significant increase in general incidence of tumours, particularly liver tumours and hemoblastoses in CBA females and malignant liver tumours in CBA males.

[Carcinogenic action of soot extracts and the composition of the aromatic polycyclic hydrocarbons in emissions of the coke chemical industry]. / Kantserogennoe deistvie ékstraktov sazhi i sostab politsiklicheskikh aromaticheskikh uglevodorodov v vybrosakh koksokhimicheskogo proizvodstva.

Carcinogenicity of the extract of "unorganized" emission of coke-oven batteries of the coke and by-product processes, 15 polycyclic hydrocarbons (PAH), solution of 4 carcinogenic PAH and benz(a)pyrene (BP) was studied in longterm experiments on (CBAXC57Bl/6)F1 hybrid mice. 1.5 ml of olive oil containing 1 mg of BP or the respective amount of PAH proportionally to their content in the extract were administered to each mouse. The sarcomas developed in 46.6% of mice which had received injections of the extract and in 95 to 100% of mice which had received injection of PAH and BP solution. Thus, the results demonstrated that besides carcinogenic PAH the emissions contain substances which inhibit the tumour development. Our data confirm a possibility of using BP as an indicator in the evaluation of carcinogenicity of industrial emission discharges of the coke and by-product processes.

[Analysis of uterine sarcoma induced in mice in terms of the two-staged development of tumors]. / Analiz indutsirovaniia sarkomy matki u myshei s tochki zreniia gipotezy o dvukhstadiinom razvitii opukholei.

The results of combined treatment of CBA female mice with 1,2-dimethylhydrazine (DMH) and estradiol dipropionate (EP) are discussed in terms of a two-stage carcinogenesis hypothesis. 20% of mice treated with DMH alone developed uterine sarcomas. EP given after the cessation of DMH-treatment increased sarcoma incidence as high as 60.6% (5 micrograms EP) or 66.7% (10 micrograms EP) and significantly decreased the time of the first tumour appearance. From the standpoint of the two-stage carcinogenesis it is considered possible for EP to influence the tumour-initiating stage.

[Stimulating action of estradiol dipropionate on uterine sarcomagenesis induced by 1,2-dimethylhydrazine in mice]. / Stimuliruiushchee deistvie éstradiola dipropionata na sarkomogenez matki, indutsiruemyi 1,2-dimetilgidrazinom u myshei.

CBA female mice received weekly subcutaneous injections of 1,2-dimethylhydrazine (1,2-DMH) in a dose of 8 mg/kg for 10 weeks (group 1). In groups 2,3 and 4 1,2-DMH plus estradiol dipropionate were administered for 10, 20 or 25 weeks, respectively. The incidence of uterine sarcoma in groups 1, 2, 3 and 4 was 3.3, 2.5, 65.4 and 73%, respectively. The mice given estradiol dipropionate alone developed no uterine sarcomas. Possible mechanisms of the uterine sarcomogenesis stimulation by estrogen are discussed.

[Mutagenic and carcinogenic actions of some polycyclic aromatic hydrocarbons]. / O mutagennom i kantserogennom deistvii riada politsiklicheskikh apromaticheskikh uglevodorodov.

The carcinogenic and mutagenic actions of benz(a)pyrene (BP) and its derivatives 6-methyl-, 6-formyl-, 6-chloro-, 6-hydroxy-, 6-acetoxy-, 6-methoxy- and 4(5)-methoxy-BP were studied in mice and bacteria Salmonella typhimurium TA-98 and TA-100, respectively. The potent carcinogenic agents BP, 6-methyl-, 6-formyl-BP proved also mutagenic in bacteria of both strains. Weak carcinogenic compounds (6-chloro-, 6-methoxy-, 4(5)-methoxy-BP) and noncarcinogenic ones (6-acetoxy-, 6-hydroxy-BP) either turned out nonmutagenic or mutagenic in one of two bacterial strains tested. The differences in carcinogenic and mutagenic actions of the substances under study are not relative to the rate of their oxidation in the enzymatic system.

[Effect of 7,8-benzoflavone on the incidence of skin tumors induced by polycyclic hydrocarbons]. / Deistvie 7,8-benzoflavona na chastotu vozniknoveniia opukholei kozhi, vyzvannykh politsiklicheskimi uglevodorodami.

Tumours were induced in CBA mice or (C57BL X CBA)F1 hybrids by the application of benz(a)pyrene (BP), 6-methylBP, 6-formylBP or 7,12-dimethylbenzanthracene (DMBA) to the skin. 7,8-benzoflavone (BF) used in combination with the mentioned agents decreased the carcinogenic action of methyl-substituted hydrocarbons--DMBA and 6-methylBP and had no effect on the carcinogenic action of BP and 6-formylBP. It is suggested that the inhibitory action of BF on carcinogenesis induced by methyl-substituted hydrocarbons was due to the inhibited oxidation of the methyl group.

Study of extracts of barley grain infected with Fusarium sporotrichioides No. 63.

Experiments with mice showed that an aqueous extract of barley grain attacked by by Fusarium sporotrichioides is blastomogenic, but only mildly so.

Hepatocarcinogenesis and the appearance of serum alpha-fetoprotein in mice treated with extracts of barley grain infected with Fusarium sporotrichioides.

Experiments demonstrated a significant association between the presence of tumours in mice and AFP positivity, while AFP negativity was usually associated with the absence of tumours. The presence of AFP in the serum of tumour-bearing mice was possibly related to treatment with F. sporotrichioides extract.