[Modification of the body's resistance to acute ionizing radiation by synthetic beta-carotene]. / Modifikatsiia sinteticheskim beta-karotinom rezistentnosti organizma k ostrym ioniziruiushchim vozdeistviiam.

Radiomodifying efficiency of short-term and chronic medicinal and treatment-prophylactic enrichment of rations with artificial beta-carotene, administered at single doses of 0.1-10.0 mg, were studied after acute external gamma-irradiation of adult nonlinear and Wistar rats (0.029 Gy/s) or female SBA mice (0.0037 Gy/s), where the absorbed dose was equal to 8-3 Gy or 9.9-9.5 Gy, respectively. Suspension of beta-carotene paste in olive oil accelerated death of rats irradiated at doses of 8 and 7 Gy (P = 0.04), and shortened their lifespan. At a dose of 6 Gy single and long-term enrichment of rations with beta-carotene decreased the rate of rat death within 30 days from 33.3% to 16.7% (P = 0.14) and 3.3% (P = 0.01), while their life time was increased from 48 days to 67 days (P = 0.05) and 508 days (P = 0.01). beta-Carotene was found to affect favourably the radiation-induced (5 Gy) leukocytopenia, and decreased thymus mass (6 Gy) and body weight (8 Gy). In treatment-prophylactic enrichment with beta-carotene of mice (9.9 Gy) ration their survival was increased from 15% to 30% and lifespan from 14.4 days to 28.9 days (P = 0.05). During medicinal or treatment-prophylactic courses of beta-carotene death of mice (9.7 Gy) was decreased from 75% to 35% (P = 0.01) or 60% and life time was increased from 16.7 days to 22.17 days or 39.9 days (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

[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.

[Prospects of the use of beta-carotene enriched food products in the prevention and therapy of radiation injuries]. / Perspektivy ispol'zovaniia obogashchennykh beta-karotinom pishchevykh produktov v profilaktike i terapii luchevykh porazhenii.

Radio-protective effectiveness of short-term (19 and 4 h before, 4 and 24 h after irradiation), long-term (3 times/week during 30 days after irradiation) and delayed (1 or 2 days after irradiation) enrichment with crystallized beta-carotene, in single doses of 0.1, 1.0 or 5.0 mg was evaluated in experimental acute external gamma-irradiation (0.029 Gy/sec) within the range of absorbed doses 9--6 Gy. The results obtained have permitted the authors to recommend the ration enriched with carotinoid for prevention and therapy of acute radiation injuries.

[The radioprotective efficacy of karotinil under acute external and internal irradiation]. / Radiozashchitnaia éffektivnost' karotinila pri vneshnem i vnutrennem ostrom obluchenii.

Radioprotective, with respect to the whole body and reproductive system, geroprotective and anticarcinogenic properties of carotinyl after single acute external gamma-irradiation or exposure to tritium oxide have been revealed. It is concluded that the use of beta-carotene-containing substances is highly promising in preventing remote effects of chronic irradiation at low rates of absorbed doses, particularly the effects of incorporated radioactive substances.

[Quantitative patterns of a model of intratracheal administration in an experiment]. / Kolichestvennye zakonomernosti modeli vnutritrakheal'nogo vvedeniia v éksperimente.

The distribution of 239PuO2 (241Am) and BeO (7BeO) within the lungs of rats and dogs after the intratracheal administration was found to follow a normal law. The amplitude of deposition variations reached 98 per cent of the amount administered. It is recommended to group the experimental animals by individual deposition estimates.

[Alloxan cytotoxicity: a new aspect of the problem]. / Tsitotoksichnost' alloksana: novyi aspekt problemy.

The effect of alloxan on human intact erythrocytes (in the suspension and whole blood) was studied using an original potentiometric apparatus permitting continuous registration of the flow rate of reducing equivalents ('RE) through a plasmatic membrane. Acceleration of RE flow from erythrocytes due to the activation of hexosomonophosphate shunt (HMPS) was established. This effect was inhibited by P-chlormercury benzoate proving the involvement of the SH-groups of erythrocyte membrane proteins in the interaction of alloxan with erythrocytes. Oxygen consumption after adding alloxan was recorded by polarography that indicated the "start" of the alloxan----dialuric acid (A in equilibrium with DA) cycle. Enhanced RE production in erythrocytes may be caused by H2O2 and free radicals forming in this cycle. It was shown that HMPS activation i.e. transition to a more intense stationary regimen was maintained for a period exceeding the calculated period of alloxan "halt--life". This residual effect of alloxan "depleted" erythrocyte protective mechanisms that was expressed in a decrease in maximum capacity of HMPS of rat whole blood after receiving by the animals a diabetogenic dose of alloxan (150 mg/kg body mass). Thus a specific cumulation of the effect of alloxan expressed in the transition of the RE generation system to a more intense stationary regimen, was revealed. In investigating the mechanism of alloxan cytotoxicity one should take into account this peculiarity of alloxan along with the factor of affinity and conditions for initiation of the A in equilibrium with DA cycle.