[Carcinogenic components of smokeless tobacco and tobacco-free cigarettes].

The investigation deals with an assessment of carcinogenicity and mutagenicity of samples of smokeless tobacco now on the Russian market as well as ash from alternative cigarettes made of aromatic herbs. Our data showed that the levels of polycyclic aromatic hydrocarbons, volatile and tobacco-specific N-nitrosoamines complied with the standards in the producer-countries. Smokeless tobacco extracts failed to show (Ames) any mutagenic effects such as the "read-out frame shift" or "base-pair replacement" patterns. No tobacco-specific N-nitrosoamines were identified in herbal cigarettes. However, polycyclic aromatic hydrocarbons and volatile N-nitrosoamines content appeared to be identical to that of tobacco. Herbal cigarette smoke extracts mutagenicity induced by side-effects of carcinogenic substances was of similar magnitude as well.

Effect of beta-carotene supplementation on the activity of ornithine decarboxylase (ODC) in stomach mucosa of patients with chronic atrophic gastritis.

Increase of ornithine decarboxylase (ODC) activity is known to be associated with cell proliferation and, very likely, with tumour promotion. This prompted us to study the activity of ODC in gastric mucosa of patients with chronic atrophic gastritis that has been considered as a precursor of stomach cancer. Examination of 124 patients with this disease revealed the considerable increase in ODC activity in atrophic mucosa (29.8 +/- 2.9 vs 7.9 +/- 1.8 units in normal mucosa, p = 0.001). Supplementation of the patient's diet with beta-carotene (20 mg daily during 3 weeks) results in a statistically significant decrease in ODC activity in gastric mucosa. The data obtained confirm the possibility of application of ODC determination to the detection of early premalignant lesions and suggest the antipromoter activity of beta-carotene in gastric carcinogenesis.

[The effect of beta-carotene on the dynamics of ornithine decarboxylase activity in atrophic mucous membranes and in stomach polyp tissue]. / Vliianie beta-karotina na dinamiku aktivnosti ornitindekarboksilazy v atroficheskoi slizistoi obolochke i v tkani polipov zheludka.

Activity of ornithine decarboxylase was significantly increased, reaching the maximal values in malignant gastric tissues, in mucosal membrane and polypous tissue of patients with atrophic gastritis as compared with normalcy. Any alterations in the enzymatic activity were not observed in the gastric mucosal membrane of 19 patients with atrophic gastritis within 3 weeks. At the same time, statistically significant decrease of the abnormal high activity of ornithine decarboxylase was detected in atrophic gastric mucosal membrane of 12 patients among 20 patients examined, which were treated with 20 mg of beta-carotene daily within 3 weeks; the enzyme activity was decreased also in polypous tissue of 5 patients in the group of 9 patients studied. Decrease in the ornithine decarboxylase activity after beta-carotene treatment involved improvement of the mucosal membrane state, where hemorrhage disappeared and inflammation reduced. Since the high activity of ornithine decarboxylase is related to promotion of cancerogenesis, beta-carotene appears to exhibit an anticarcinogenic effect as it decreases the enzymatic activity in gastric mucosal membrane.