[en] The data considered confirm that the greatest lethal effect of radiations with high LET is caused by increased probability of primary radiation injury formation in cells and by decreasing the cell capability to reparation. Decrease of RBE value of censely ionizing radiations by factors of gene mutations and chromosomal aberrations, when radiation dose increasing, is caused by high probability of cell-carrier death of such damages after radiation effect with high density of ionization. For the first time, the explanation of causes for high occurrence of intestinal syndrome in animals after the effect of radiation with high density of ionization is given. Besides, experimental data on the absense of qualitative specificity of injuries after densely and sparsely ionising radiation effect in organism are considered

[en] Possible action mechanisms of chemical radioprotectors (aminothiol and indolylalkylamines) and their role in the repair of DNA propariots are considered. Restitution is suggested to play a leading part in the radiation protection effect of the radioprotectors studied. Experimental facts favouring this hypothesis are presented. The possibilities of inhibiting post radiation DNA degradation with chemical protectors are discussed

No abstract available

[en] It has been studied whether there is a correlation of the radioprotective effect of cystamine (50 and 150 mg/kg by base) and its analogue, N',N'-tetramethyl cystamine (130 mg/kg by base), with the ability of these compounds to rise the endogenous serotonin content of radiosensitive organs 20 and 60 minutes after intraperitoneal administration to mice. The ability of sulphur-containing radioprotectors does not necessarily correlate with their preventive properties: an ineffective radioprotector analogue, N',N'-tetramethyl cystamine, has the same effect on the endogeneous serotonin level as the protector itself

[en] Irradiation of isolated frog sympathetic ganglia 9-10 with high doses caused a long-term depolarization of a single ganglion cell and increase of synaptic activation threshold. The radiation effects obesrved were not accompanied by the transmission failure. The authors suggest that the changes in the synaptic mechanisms play a minor role in the development of the CNS-syndrome

[en] It has been demonstrated by centrifuging in a neutral sucrose gradient that total-body irradiation of rats with fast neutrons of fission spectrum (230 rad) causes an irreversible decrease in the polymeric properites of the nuclear DNA of the spleen during the first four days following the exposure. It has been shown by the method of thermal fractionation on columns with hydroxylapatite that melting temperature of the spleen DNA of the animals exposed to neutrons does not vary from the controls 2 and 4 days after irradiation, whereas after X-irradiation, melting temperature decreases within these time-intervals. Thus, the mode of postirradiation changes in the DNA structure is different after X- and neutron irradiation

[en] Heating of mouse bone marrow cells up to 42 deg C was shown to increase their radiosensitivity (DMF=0.80+-0.12). At this temperature, the radioprotective efficiency of cysteamine was lost completely (DMF=0.78+-0.09), and radioprotective activity of d, l-isoproterenol significantly decreased (DMF declined from 2.41+-0.23 to 1.67+-0.16). It is assumed that the radioprotective effect of cysteamine on mammalian cells is associated with the processes of the postirradiation DNA repair for just these processes are inhibited by heating. The mechanism of action of a β-agonist of isoproterenol is perhaps only partially associated with DNA repair

[en] Most of the blue spot neurons of Wistar rats exhibited a pronounced central chromatolysis of 24 h following irradiation with fission neutrons (above 100 Gy) and γ-quanta (above 200 Gy). The changes in the mesencephalic nucleus of the trigeminal nerve were distinct on day 2 after 200 Gy γ-irradiation. The number of the modified nervous cells in these regions was higher than that in other brain parts

No abstract available

[en] It was shown on Golden hamsters, which are characterized by high radioresistance of the intestine, that S-2-(ß-aminopropylaminoethyl) thiophosphorous acid (gammaphos) exerts a protective action against both X- and neutron-radiation although in the latter case the protection is less pronounced. In conditions of hibernation, the protective effect of gammaphos against X-radiation was not statistically reliable. Hibernation during exposure and at the postirradiation period increases considerably the radioresistance of animals. The influence of hibernation depends upon its duration