Radiobiologiia最新文献

It has been shown that single local X-irradiation (0.21 C/kg) of the rabbit hind limb in the early period of acute radiation injury (1 and 14 h) causes a decrease in saturation of sarcoplasmic reticulum membrane lipids. It is mainly connected with a decreased saturation of the total fraction of phosphatidyl serine, phosphatidyl inositol and phosphatidyl choline. The above changes can increase permeability of the sarcoplasmic reticulum membranes for Ca(2+)-ion after X-irradiation.

Examination of 339 children at the age of 2 to 12 years, living in the caesium contaminated region (from 2 to 5 Ci/km2) has revealed that total radioactivity of their urine is, on the average, twice as high as that of children living in "pure" regions. Quantitative and qualitative changes were observed in the erythroid series, neutrophilic leukocytes, eosinophils and B-lymphocytes of the peripheral blood of children subjected to long-term low-level irradiation. It should be noted that the character and direction of these changes were a function of the children's age and the level of total radioactivity of their urine.

As early as 5-7 min after the start of exposure of tissue preparations from rat trachea ciliated epithelium to gamma-radiation at a dose rate of 19 mGy/h, the ciliary motion rate increased periodically. The phenomenon of increasing the ciliary motion occurred more frequently in time; the intervals between two frequency drops became longer and the mean frequency level higher. The reverse sequence of the events was observed during the postirradiation period. The same regularities, but less expressed, were observed after irradiation at a dose rate of 1.8 mGy/h.

Compounds that increase the survival rate of lethally exposed hybrid (CBA x C57B1/6)F1 mice have been revealed within the series of iminodihydrofurans. The quantum-chemical estimates, made by the MNDO method, show that substances which are capable of donor-acceptance interaction with DNA nucleotides and have the energy of donor orbitals, comparable with the electron structure of nucleotides, possess radioprotective efficacy.

A study was made of hydrobionts, particularly fishes, living within the thirty-kilometer control zone of Chernobyl NPP and northern part of the Kiev basin, after the disaster. Out of 31 fish species living in the NPP cooling pond some were identified which were mostly affected by radioactive contamination. They were predators belonging, with respect to reproduction and development, to a lithophilous group. Peculiarities of reproduction of Hypophthalmichthys molitrix kept in stews of the cooling pond before the accident were studied. After a three-year exposure to ionizing radiation (cumulative dose of 8-9 Gy) no reduction in the reproductive capacity of mature fishes was observed.

The present paper deals with the damages that are induced by numerous agents, such as gamma-radiation, UV-radiation, visible fluorescent light radiation, and a wide range of chemical agents, and lead to the formation of DNA-protein cross-links. This is the most unknown and obscure type of damage to cells. It is, however, well known that these damages are reparable.

Mathematical models have been developed to describe dynamics of some haemopoietic compartments in mammals subjected to long-term irradiation. Within the framework of the models developed an equation has been obtained for a critical dose-rate (Ncr) of chronic irradiation, leading to complete depletion of certain haemopoietic compartments, that helps to prognose the dangerous Ncr values without preliminary experiments.

In experiments with mice, the efficiency of radioprotective agents against acute gamma-irradiation with nonlethal and low doses (0.5-4 Gy) was estimated by nine parameters. The treatment with cystamine, cysteamine and riboxine prior to irradiation (< 2 Gy) did not influence the postirradiation values of the parameters under study. With a dose of up to 4 Gy, the effect of riboxine was noted. The determinations of the number of aberrant mitoses, cellularity and mitotic activity of the bone marrow have proved to be most informative. The data obtained are discussed with due regard for the specific effect of low-level radiation and mechanisms of the protective action of the agents under study.

The lipid peroxidation level and the antioxidant system status have been studied by the amount of alpha-tocopherol and the antioxidant activity of homogenates in the brain, liver, heart and somatic muscle of rats given Vitamins A and E, as physiological additives, before and after gamma-irradiation. It has been shown that a new dynamic balance between the parameters under study is rapidly set up after irradiation, which represents a mechanism of rapid adaptation. The radioprotective effect of alpha-tocopherol is more pronounced than that of Vitamin A (particularly in the brain). In most cases, Vitamin A produces, upon irradiation, an unfavourable effect on antioxidative homeostasis.