Effects of sublethal irradiation with helium ions (300 MeV/nucleon) on basic hematological parameters of mice.

The aim of the experiment was to obtain new knowledge on the biological effectiveness of high-energy (300 MeV/nucleon) helium ions, which represent a part of the spectrum of cosmic rays. Male (CBA x C57BL)F1 mice, 4 months old, were exposed to a dose of 4 Gy helium ions (exposure rate 0.05 Gy/min). As a comparative standard irradiation the same dose of 4 Gy of 137Cs gamma-rays (exposure rate 0.07 Gy/min) was used. Material sampling was performed 6-8 h, 4 days and 9 days after irradiation for both experimental groups mentioned above. There were 7 animals in each group including the control group of non-irradiated mice. Eight basic hematological parameters of peripheral blood, bone marrow, spleen and thymus were studied. On day 4 after the irradiation with helium ions, the values of leukocyte counts in peripheral blood, bone marrow cellularity and spleen cellularity were reduced to about 10% of the respective control values while the decline after irradiation with gamma-rays amounted to about 50%. These and other results presented reflect a high relative biological effectiveness of 300 MeV/nucleon helium ions.

[The occurrence of cataract in rats as one of the factors worsening the quality of their lives in the late periods after whole-body and partial irradiation]. / Vozniknovenie katarakty u krys kak odin iz faktorov ukhudsheniia kachestva ikh zhizni v otdalennye sroki posle obshchego i partsial'nogo oblucheniia.

A study was made of the formation of cataract in rats at remote times after whole-body and partial X irradiation. The whole-body radiation loses were 5 and 10 Gy (two fractions of 5 Gy at a 30-day interval). Partial exposure of the head and neck, as well as irradiation of chest were performed with doses of 5, 10 (two fractions at a 30-day interval) and 15 Gy (three 5 Gy fractions at a 30-day interval). It has been shown that cataract develops not only due to the direct effect of radiation on the eye, but also to indirect effect on the experimental animal body (with irradiation of the abdomen and diabetes development).

[Cataractogenic action of accelerated carbon ions with energies of 300 MeV/nucleon]. / Kataraktogennoe deistvie uskorennykh ionov ugleroda s énergiei 300 MéV/nuklon.

The influence of carbon ions of 300 MeV/nucleon on the incidence of lenticular opacity has been studied on mice. The cataractogenic efficiency of low carbon ion doses (0.003 to 0.5 Gy) is higher than that of gamma-radiation. The threshold dose of carbon ions is 0.05 Gy. The RBE ratios vary from 30.4 to 11.1 as the period of the postirradiation observation increases from 20 to 50 weeks.

[The fluorescence of mouse crystalline lenses at different stages of radiation cataract studied by synchronous scanning]. / Izuchenie fliuorestsentsii khrustalikov myshei na razlichnykh stadiiakh radiatsionnoi katarakty metodom sinkhronnogo skanirovaniia.

Fluorescence of intact lenses of F1 (CBA x C57BL6) mice at different stages of X-ray cataract induced by gamma irradiation (5.00 Gr) has been studied by synchronous scanning of fluorescence, the shift between emission and excitation wave lengths being 20 nm. The ratio between peek intensities of the nontryptophan and tryptophan fluorescence within the synchronous scanning spectra (K) has increased 3.5 times as much at the stage of singular dot-like opacities. K-parameter correlated with GSH level in the lenses (r = -0.9). According to the results achieved, K could be regarded as an informative indicator of the development of X-ray cataract at the stage previous to turbidity.

[Biological effectiveness of helium ions and relativistic-energy protons]. / Biologicheskaia éffektivnost' ionov geliia i protonov reliativistskikh énergii.

It was shown that RBE coefficients of protons (9 GeV) and accelerated helium ions (4 GeV/nucleon) are within the range from 1.0 to 11.6 and 1.0 to 7.2, respectively, depending on the object under study, the criterium of estimation, the registration time, and the dose value.

[Evaluation of the cataractogenic effect of 9 GeV protons]. / Otsenka kataraktogennogo deistviia protonov s énergiei 9 GéV.

A study was made of the regularities of formation of lenticular opacity in mice exposed to 9 GeV protons and 60Co-gamma-rays. The RBE coefficients, calculated by the nonparametric method, were found to depend upon dose and time after irradiation. It was shown that after small radiation doses (0.25 to 0.50 Gy) the RBE coefficients increased from 1 to 8 with increasing period of observation. With higher doses (up to 5.0 Gy) the RBE coefficient increase in time was less pronounced.

A contribution to the morphological study of acute changes in the blood vessels of the central nervous system of rats following irradiation with high-energy (4 GeV/nucleon) helium ions.

Rats were irradiated with helium ions (4 GeV/nucleon; 2 or 4 Gy). After 4-9 hours or three days, a perfusion was performed and sections of the cerebral cortex were investigated under light and electron microscopes. Changes observed in the vessels of the telencephalic cortex are described. Most of the vessels in the sections analysed showed no signs of damage. In some cases there was a dilated perivascular space; a comparison of its occurrence in irradiated and control animals showed a statistically significant increase in frequency of the phenomenon at a shorter interval after irradiation with a larger dose. Electron microscopical analysis showed that the main locality of damage was the border of the perivascular foot of the astrocytes, which exhibited various degrees of edema. The discussion stresses the peculiarities of the interaction of helium ions with living tissues, particularly the heterogeneity of the distribution of absorbed energy. The consequence is in accordance with the nature of the changes observed.

[Lens opacity in mice exposed to helium ions with energy of 4 GeV/nuclon and gamma-irradiation with Co-60]. / Pomutneniia khrustalika u myshei, obluchennykh ionami gelia s energiei 4 GeV/nuklon i gamma-izlucheniem 60Co.

The cataractogenic effect of helium ions with the energy 4 GeV/nuclon and 60Co gamma-radiation was examined. In response to helium irradiation the cataract incidence and maturation rate was higher than in response to gamma-irradiation at the same doses. The RBE coefficients of helium ions were calculated from the equally effective doses of reference and helium irradiations. They depended on the exposure duration and amounted to 1.2 +/- 0.1, 2.2 +/- 0.1, and 2.6 +/- 0.1 by post-irradiation weeks 20, 30, and 40, respectively.

[Cataractogenic effect of protons with energies of 25 and 50 MeV]. / Kataraktogennoe deistvie protonov s énergiiami 25 i 50 MeV.

The frequency of cataract formation in mice was studied during their exposure to protons of 25 and meV and X-rays of 200 kV at doses of 100-600 rad. The frequency of cataract formation was a function of the irradiation dose and postirradiation time. The frequency of occurrence and intensity of development of radiation-induced cataracts was related to the dose rate. No qualitative differences in the clinical picture of the formation and development of cataracts indlced by protons or by X-rays were noted. The RBE coefficients of 25 and 50 meV protons approximated a unit.