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内容記述 |
Effects of radio-protective and radio-mitigative compounds against carbon-ion beam induced bone-marrow death of mice was investigated. Radio-protector, i.e. amifostine or cysteamine, was intraperitoneally administered 30 min before carbon-ion beam irradiation with a dose of 1.95 mmol/kg body weight. Rdio-mitigator, i.e. zinc-containing heat-killed yeast (Zn-yeast) or γ-tocopherol-N,N-dimethylglycine ester (γTDMG), was intraperitoneally administered immediately after carbon-ion beam irradiation with a dose of 100 mg/kg body weight. Dependence of 30-day survival rates after carbon-ion irradiation to the irradiation doses was analyzed, and then LD50/30 value was obtained as 5.54 Gy for carbon-ion beam and 6.62 Gy for X-ray. Relative biological effectiveness of carbon-ion beam was estimated as 1.2 compare to the X-ray. Dose reduction factor (DRF) of radio-protectors, i.e. amifostine and cysteamine, estimated for carbon-ion irradiation was 1.75 and 1.53, and that of radio-mitigators, i.e. Zn-yeast and γTDMG, was 1.16 and 1.15, respectively. Both radio-protectors and radio-mitigators efficiently effective on photon irradiation, were also effective on carbon-ion irradiation, although the DRF for carbon ion irradiation were slight smaller compared to that for photon irradiation. Due to the DRF of amifostine for carbon-ion beam was almost 70% of that for photon irradiation, the weight of ROS/free radical mediated effect on carbon-ion beam induced bone-marrow death was mostly 70% of that of photon irradiation. |
