[Certain parameters of beta-carotene metabolism in the rat]. / Nekotorye parametry metabolizma beta-karotina v organizme krys.

Concentration of retinoids was decreased from 24.5 micrograms/100 ml to 13.5 micrograms/100 ml of blood serum in rats with ageing, during 2-11 months; these rats were maintained on a standard ration. Enrichment of rat ration with beta-carotene caused a statistically significant increase in content of retinoids in blood serum from 24.5 micrograms/100 ml to 48.6 micrograms/100 ml within early periods (1-72 hrs), while within later periods (0.25-2 months) the retinoid content was similar to that of control intact animals. After single and, especially, in long-term treatments with beta-carotene dose-dependent deposition of the carotenoid and increase in content of retinoids were detected in liver tissue. Use of white rats is of importance in principle for evaluation of beta-carotene caused modifications of pathological states developed under influence of unsuitable environmental factors.

[Carcinogenic effect of long-term fractionated gamma-irradiation]. / K voprosu ob opukholevom deistvii dlitel'nogo fraktsionirovannogo gamma-oblucheniia.

The incidence of malignant tumors increased and the average life decreased at remote times following long-term fractionated gamma-irradiation. Life shortening only exhibited a strict dependence on the cumulative radiation dose.

[Morphological changes in the intrapulmonary bronchi of rats a long time after 239PuO2 inhalation]. / Morfologicheskie izmeneniia vnutrilegochnykh bronkhov u krys v otdalennom periode posle ingaliatsii 239PuO2.

Destructive, inflammatory, sclerotic, compensatory and adaptive, pretumoral and tumoral changes in the respiratory tracts of rats were revealed 180-540 days following a single inhalation of 239PuO2. The thickness of the bronchus wall and the diameter of their lumen remained significantly increased, as compared with the controls of the same age, throughout the entire period of observation.

[Comparative evaluation of the carcinogenic effects of chronic exposure to tritium oxide and external gamma-radiation]. / Sravnitel'naia otsenka blastomogennogo éffekta khronicheskogo deistviia okisi tritiia i vneshnego gamma-oblucheniia.

In experiments of on rats a study was made of late effects of chronic action of tritium oxide (3HOH) during 6 months (37 X 10(4) Bq/g/day) and external gamma-radiation (137Cs) which were delivered in comparable daily and cumulative doses. It was shown that 3HOH produced a more pronounced blastomogenic effect. The RBE coefficient of tritium oxide approximated 1, with a reference to the average life shortening, and 4.2 and 2.5, with a reference to the incidence of malignant tumors and leukoses, respectively.

[Characteristics of a monolayer culture of bone marrow cells in rats with plutonium 239-induced osteosarcomas]. / Kharakteristika monosloinoi kul'tury kletok kostnogo mozga krys s osteosarkomami, indutsirovannymi plutoniem-239.

The report is concerned with a monolayer culture of bone marrow cells of rats in which optimal blastogenic dose (92.5 kBq/kg) induced osteosarcoma. The cell culture showed an enhanced rate of fibroblast-like cell proliferation (increased number of mitoses and symplasts and larger colonies of cells), apparent signs of radiation injury (pathologic mitoses, chromosome aberrations and gaps) as well as an increase in ploidy. Diffusion chamber measurements demonstrated osteogenic precursor-cells in osteosarcoma-bearing rats to be highly capable of bone formation. This relatively high ability seems to occur outside bone marrow as well.