Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604512004Inhibitory Effects of Prior Low-dose X-ray Irradiation on Carbon Tetrachloride-induced Hepatopathy in Acatalasemic Mice8995ENKiyonoriYamaokaTakahiroKataokaTakaharuNomuraTakehitoTaguchiDa-HongWangShujiMoriKatsumiHanamotoShoheiKiraThe catalase activities in blood and organs of the acatalasemic (C3H/AnLCs<sup>b</sup>Cs<sup>b</sup>) mouse of C3H strain are lower than those of the normal (C3H/AnLCs<sup>a</sup>Cs<sup>a</sup>) mouse. We examined the effects of prior low-dose (0.5 Gy) X-ray irradiation, which reduced the oxidative damage under carbon tetrachloride-induced hepatopathy in the acatalasemic or normal mice. The acatalasemic mice showed a significantly lower catalase activity and a significantly higher glutathione peroxidase activity compared with those in the normal mice. Moreover, low-dose irradiation increased the catalase activity in the acatalasemic mouse liver to a level similar to that of the normal mouse liver. Pathological examinations and analyses of blood glutamic oxaloacetic and glutamic pyruvic transaminase activity and lipid peroxide levels showed that carbon tetrachloride induced hepatopathy was inhibited by low-dose irradiation. These findings may indicate that the free radical reaction induced by the lack of catalase and the administration of carbon tetrachloride is more properly neutralized by high glutathione peroxidase activity and low-dose irradiation in the acatalasemic mouse liver.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604612005The Elevation of p53 Protein Level and SOD Activity in the Resident Blood of the Misasa Radon Hot Spring District2124ENKiyonoriYamaokaFumihiroMitsunobuShujiKojimaMisakoShibakuraTakahiroKataokaKatsumiHanamotoYoshiroTanizakiTo clarify the mechanism by which radon hot springs prevent cancer or not, in this study, blood was collected from residents in the Misasa hot spring district and in a control district. The level of a representative cancer-suppressive gene, p53, and the activity of a representative antioxidant enzyme, superoxide dismutase (SOD), were analyzed as indices. The level of serum p53 protein in the males in the Misasa hot spring district was found to be 2-fold higher than that in the control district, which is a significant difference. In the females in the Misasa hot spring district, SOD activity was approximately 15% higher than that in the control district, which is also statistically significant, and exceeded the reference range of SOD activity despite advanced age. These results suggested that routine exposure of the residents in the Misasa hot spring district to radon at a concentration about 3 times higher than the national mean induces trace active oxygen in vivo, potentiating products of cancer-suppressive gene and antioxidant function. As the p53 protein level was high in the residents in the Misasa hot spring district, apoptosis of cancer cells may readily occur.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604862007Inhibitory Effects of Prior Low-dose X-irradiation on Ischemia-reperfusion Injury in Mouse Paw505513ENTakahiroKataokaYukoMizuguchiMasaakiYoshimotoTakehitoTaguchiKiyonoriYamaokaWe have reported that low-dose, unlike high-dose, irradiation enhanced antioxidation function and reduced oxidative damage. On the other hand, ischemia-reperfusion injury is induced by reactive oxygen species. In this study, we examined the inhibitory effects of prior low-dose X-irradiation on ischemia-reperfusion injury in mouse paw. BALB/c mice were irradiated by sham or 0.5 Gy of X-ray. At 4 hrs after irradiation, the left hind leg was bound 10 times with a rubber ring for 0.5, 1, or 2 hrs and the paw thickness was measured. Results show that the paw swelling thickness by ischemia for 0.5 hr was lower than that for 2 hrs. At 1 hr after reperfusion from ischemia for 1 hr, superoxide dismutase activity in serum was increased in those mice which received 0.5 Gy irradiation and in the case of the ischemia for 0.5 or 1 hr, the paw swelling thicknesses were inhibited by 0.5 Gy irradiation. In addition, interstitial edema in those mice which received 0.5 Gy irradiation was less than that in the mice which underwent by sham irradiation. These findings suggest that the ischemia-reperfusion injury is inhibited by the enhancement of antioxidation function by 0.5 Gy irradiation.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30605262011Study of the Response of Superoxide Dismutase in Mouse Organs to Radon Using a New Large-scale Facility for Exposing Small Animals to Radon775781ENTakahiroKataokaAkihiroSakodaYuuIshimoriTeruakiToyotaYuichiNishiyamaHiroshiTanakaFumihiroMitsunobuKiyonoriYamaokaWe examined dose–dependent or dose rate–dependent changes of superoxide dismutase (SOD) activity using a new large-scale facility for exposing small animals to radon. Mice were exposed to radon at a concentration of 250, 500, 1000, 2000, or 4000 Bq/m<sup>3</sup> for 0.5, 1, 2, 4, or 8 days. When mice were exposed to radon at 2000 day•Bq/m<sup>3</sup>, activation of SOD activities in plasma, liver, pancreas, heart, thymus, and kidney showed dose–rate effects. Our results also suggested that continuous exposure to radon increased SOD activity, but SOD activity transiently returned to normal levels at around 2 days. Moreover, we classified the organs into four groups (1. plasma, brain, lung; 2. heart, liver, pancreas, small intestine; 3. kidney, thymus; 4. stomach) based on changes in SOD activity. Thymus had the highest responsiveness and stomach had lowest. These data provide useful baseline measurements for future studies on radon effects.No potential conflict of interest relevant to this article was reported.