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Kataoka, Takahiro*; Shuto, Hina*; Naoe, Shota*; Yano, Junki*; Kanzaki, Norie; Sakoda, Akihiro; Tanaka, Hiroshi; Hanamoto, Katsumi*; Mitsunobu, Fumihiro*; Terato, Hiroaki*; et al.
Journal of Radiation Research (Internet), 62(5), p.861 - 867, 2021/09
Times Cited Count：5 Percentile：55.27(Biology)Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Shuto, Hina*; Yano, Junki*; Naoe, Shota*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
Journal of Radiation Research (Internet), 62(2), p.206 - 216, 2021/03
Times Cited Count：6 Percentile：61.83(Biology)Radon inhalation activates antioxidative functions in mouse organs, thereby contributing to inhibition of oxidative stress-induced damage. Therefore, in this study, we evaluated the redox state of various organs in mice following radon inhalation. Mice inhaled radon at concentrations of 2 or 20 kBq/m
for 1, 3, or 10 days. The relationship between antioxidative function and oxidative stress was evaluated by principal component analysis (PCA) and correlation coefficient compared with control mice subjected to sham inhalation. These findings suggested that radon inhalation altered the redox state in organs, but that the characteristics varied depending on the redox state in organs.
Kataoka, Takahiro*; Tokunaga, Rikizo*; Sakoda, Akihiro; Kawabe, Atsushi*; Hanamoto, Katsumi*; Yamaoka, Kiyonori*
Radioisotopes, 61(1), p.1 - 8, 2012/01
Radon inhalation using our radon exposure device activated anti-oxidative function in some organs of mouse. To assess the possibility of its application to veterinary care, healthy dogs and cats with chronic renal failure were inhaled radon at a concentration of 5500 Bq/m for 30 minutes every 2 days for 30 days. In result, radon inhalation within a relatively long time period significantly decreased the triglyceride level of dogs. On the other hand, some cats increased the volume of drinking water by radon inhalation and the creatinine level in blood of these cats was decreased to normal level. These findings suggest that radon inhalation may have curative properties against chronic renal failure.
Kataoka, Takahiro*; Sakoda, Akihiro*; Yoshimoto, Masaaki*; Toyota, Teruaki*; Yamamoto, Yuki*; Ishimori, Yuu; Hanamoto, Katsumi*; Kawabe, Atsushi*; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Radiation Safety Management, 10(1), p.1 - 7, 2011/12
We examined the effect of continuous radon inhalation on acute alcohol-induced oxidative damage of mouse liver and brain. Assay of antioxidative functions indicated that lipid peroxide levels in both the liver and brain of the alcohol-treated mice were significantly higher than those of the saline-treated mice. However, the lipid peroxide level in the liver, but not in the brain, of alcohol-treated mice was significantly decreased by radon inhalation whereas that in the brain of saline-treated mice, but not in the liver of saline-treated mice, was significantly increased by radon inhalation. These findings suggest that radon inhalation inhibits alcohol-induced oxidative damage of liver due to activation of antioxidative functions and that radon inhalation exert only a week effect on the brains in comparing with the livers. They further suggest that alcohol administration protects against oxidative damage of the brain that is induced by radon inhalation.
Kataoka, Takahiro*; Sakoda, Akihiro*; Yoshimoto, Masaaki*; Nakagawa, Shinya*; Toyota, Teruaki*; Nishiyama, Yuichi*; Yamato, Keiko*; Ishimori, Yuu; Kawabe, Atsushi*; Hanamoto, Katsumi*; et al.
Radiation Protection Dosimetry, 146(1-3), p.360 - 363, 2011/07
Times Cited Count：6 Percentile：44.28(Environmental Sciences)Our previous studies showed the possibility that activation of the antioxidative function alleviates various oxidative damages, which are related to lifestyle diseases. Results showed that, low-dose X-ray irradiation activated superoxide dismutase and inhibits oedema following ischaemia-reperfusion. To alleviate ischaemia-reperfusion injury with transplantation, the changes of the antioxidative function in liver graft using low-dose X-ray irradiation immediately after exenteration were examined. Results showed that liver grafts activate the antioxidative function as a result of irradiation. In addition, radon inhalation enhances the antioxidative function in some organs, and alleviates alcohol-induced oxidative damage of mouse liver. Moreover, in order to determine the most effective condition of radon inhalation, mice inhaled radon before or after carbon tetrachloride (CCl
) administration. Results showed that radon inhalation alleviates CCl-induced hepatopathy, especially prior inhalation. It is highly possible that adequate activation of antioxidative functions induced by low-dose irradiation can contribute to preventing or reducing oxidative damages, which are related to lifestyle diseases.
Sakoda, Akihiro*; Ishimori, Yuu; Hanamoto, Katsumi*; Kawabe, Atsushi*; Kataoka, Takahiro*; Nagamatsu, Tomohiro*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(10), p.2013 - 2015, 2010/10
Times Cited Count：1 Percentile：9.99(Chemistry, Inorganic & Nuclear)The performance of IPs has not been studied at temperatures lower than 0
C. In the present study, an IP was irradiated with 
rays emitted from the mineral monazite at temperatures between -80 and 30C to determine its fundamental properties. The IP response as a function of irradiation time was found to be linear, suggesting that the IP works properly at low temperatures. Fading, an effect which should be considered at temperatures of more than 0C, was not observed at -30 and -80C. Furthermore, the fading-corrected PSL value of the IP irradiated at -80C was lower than at other temperatures (30, 5 and -30C). This can be explained by TSL. Since the only intensive TSL peak in the temperature range from -80 to 30C is present at about -43C, some of the electrons trapped at F centers recombine with holes through the process of TSL before the stored radiation image is read out at room temperature.
Sakoda, Akihiro*; Ishimori, Yuu; Kawabe, Atsushi*; Kataoka, Takahiro*; Hanamoto, Katsumi*; Yamaoka, Kiyonori*
Journal of Nuclear Science and Technology, 47(8), p.731 - 738, 2010/08
Times Cited Count：42 Percentile：93.07(Nuclear Science & Technology)This is the first report to provide radiation doses, arising from inhalation of radon itself, in mice and rats. To quantify absorbed doses to organs and tissues in mice, rats, and humans, we computed the behavior of inhaled radon in their bodies on the basis of a physiologically based pharmacokinetic (PBPK) model. It was assumed that radon dissolved in blood entering the gas exchange compartment is transported to any tissue by the blood circulation to be instantaneously distributed according to a tissue/blood partition coefficient. The calculated concentrations of radon in the adipose tissue and red bone marrow following its inhalation were much higher than those in the others, because of the higher partition coefficients. Compared with a previous experimental data for rats and model calculation for humans, the present calculation was proved to be valid. Absorbed dose rates to organs and tissues were estimated to be within the range of 0.04 - 1.4 nGy/(Bq/m
)/day for all the species.
Sakoda, Akihiro*; Hanamoto, Katsumi*; Ishimori, Yuu; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(6), p.1169 - 1172, 2010/06
Times Cited Count：31 Percentile：88.56(Chemistry, Inorganic & Nuclear)The present model represents an improvement on previous models of radon emanation from soil by incorporating soil grain size in addition to moisture. Monte Carlo simulation was employed in the calculation since it was difficult to mathematically express the radon emanation fraction for the present soil model. Grain size is one of the most important factors in describing the properties of soil. Grain size was demonstrated to affect the radon emanation fraction, depending on moisture content. Although the emanation fraction is generally considered to be proportional to grain size, the result of the model calculation suggested that the effect of grain size is not so simple. This study should serve as an initial step toward improving the modeling of this radon emanation.
Sakoda, Akihiro*; Nishiyama, Yuichi*; Hanamoto, Katsumi*; Ishimori, Yuu; Yamamoto, Yuki*; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(6), p.1180 - 1184, 2010/06
Times Cited Count：53 Percentile：95.31(Chemistry, Inorganic & Nuclear)We examined differences in the radioactive characteristics among the main minerals forming granite materials. Using a non-toxic high-density agent, minerals were separated from rock (granite-gneiss) and soil (weathered granite) samples. The natural radioactivity (
U and 
Ra) and radon emanation fraction of the minerals were then studied by -ray spectrometry. The radon emanation fractions (27-43%) of the minerals from the soil were much higher than those (0.6-4.6%) of the rock minerals. Additionally, the emanation fractions differed greatly among the minerals separated from both the bulk rock and soil. These results were discussed in terms of the differences of surface area and radium distribution in the mineral grains. It was noticeable that a higher emanation fraction than expected for quartz was commonly observed in the rock and soil samples. We then estimated the contribution of each constituent mineral to the total radon exhalation from the bulk samples. The result depended not only on the radon emanation fraction, but also on the Ra activity and the mineral content. Furthermore, using the obtained data, we also discussed the effect of grain size on radon emanation and why this has been reported to vary markedly in previous studies.
Sakoda, Akihiro*; Ishimori, Yuu; Hanamoto, Katsumi*; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Radiation Measurements, 45(2), p.204 - 210, 2010/02
Times Cited Count：61 Percentile：96.44(Nuclear Science & Technology)Some models have already been developed to explain the effect of moisture content on the radon emanation fraction of soil. For this purpose, "microscopic" soil models, which are easy to deal with mathematically but cannot take grain size into consideration, have been designed. These previous models consist basically of two opposite grain surfaces and pores between the grains. In the present study, in order to study the effect of not only moisture content but also grain size, we present a simple modeling approach based on two "macroscopic" soil models: (1) a single-grain model and (2) a multiple-grain model. The latter model represents a configuration of spherical grains packed in a simple cubic structure. Based on these soil models and general assumptions, the radon emanation fraction was calculated as a function of grain size or moisture content by Monte Carlo simulation. The results for the multiple-grain model show that the radon emanation fraction is markedly increased with grain sizes ranging from 10 to 100 mm and reaches a constant value of 50% when moisture content is 0% and the radium is uniformly distributed on the grain surface. Moreover, a drastic increase is seen at smaller grain sizes with increasing moisture content. From these results, we concluded that the calculation of radon emanation depends greatly on the pore size between a Ra-bearing grain and a neighboring grain. The validity of the model was also evaluated by comparison to experimental data.
Sakoda, Akihiro*; Hanamoto, Katsumi*; Ishimori, Yuu; Nagamatsu, Tomohiro*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 66(5), p.648 - 652, 2008/05
Times Cited Count：34 Percentile：88.13(Chemistry, Inorganic & Nuclear)The chemical composition was analyzed and the radioactivity, radon exhalation rate and emanation fraction were measured to investigate the characteristics of the granites sampled at Misasa and Badgastein, world famous for radon therapy. The Misasa granite was probably composed of quartz, albite and microcline. The Badgastein granite was probably composed of quartz and muscovite. The radon exhalation rates and emanation fractions of the Misasa granite were much higher than those of the Badgastein granite, regardless of the Ra activity concentrations.
Nakagawa, Shinya*; Kataoka, Takahiro*; Sakoda, Akihiro*; Ishimori, Yuu; Hanamoto, Katsumi*; Yamaoka, Kiyonori*
Radioisotopes, 57(4), p.241 - 251, 2008/04
There are a lot of life style diseases that are related to reactive oxygen species in inductions of the radon therapy, and the further clarification of mechanism is expected. In this study, we investigated the activation of antioxidation function in some organs of mice by radon inhalation using the new radon exposure device. The mice were made to inhale the radon of 400Bq/m or 4000Bq/m with the device. Results show that in brain, lungs, liver and kidney, both the activities of superoxide dismutase and catalase increased, and lipid peroxide levels decreased. This suggests that radon inhalation enhanced the antioxidation function. These findings are important in understanding the mechanism of diseases in which radon therapy is used as treatment, and most of which are called activated oxygen-related diseases.
Sakoda, Akihiro*; Hanamoto, Katsumi*; Ishimori, Yuu; Nagamatsu, Tomohiro*; Yamaoka, Kiyonori*
Radiation Measurements, 43(1), p.106 - 110, 2008/01
Times Cited Count：18 Percentile：72.86(Nuclear Science & Technology)In order to determine the best physical conditions for leaching more radon from minerals into water, we measured the leaching rate of radon from radioactive minerals under the conditions of some different grain sizes and water temperatures. Water temperature affected the leaching rate of radon although the grain size did not significantly affect it. Furthermore, we proposed ultrasonic irradiation to the mixture of a mineral and water as the method of leaching more radon. Ultrasonic irradiation was efficient to leach more radon from the mineral soaked in water because of ultrasonic cavitation.
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Ishida, Tsuyoshi; Shuto, Hina*; Yano, Junki*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
no journal, ,
We have reported that radon inhalation activates antioxidative functions in mouse organs. These activation inhibits reactive oxygen species (ROS) induced oxidative stresses. Activation of antioxidative functions induced by radon inhalation probably due to the production of a small quantity of ROS. However, there were no reports on this mechanism. In this study, we evaluated hydrogen peroxide induced oxidative stress by radon inhalation in mouse organs. That is, mice inhaled radon at a concentration of 1 kBq/m or 10 kBq/m for 24 hours. Results showed that radon inhalation increased hydrogen peroxide in liver and lung by 20%. On the other hand, hydrogen peroxide in heart decreased by 20%. This is probably due to total glutathione reacts with hydrogen peroxide. These findings suggest that radon inhalation produces a small quantity of hydrogen peroxide, which is ROS, in mouse organs. However, antioxidative related substances, which are catalase and total glutathione, play an important role to reduce oxidative stress.
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Ishida, Tsuyoshi; Shuto, Hina*; Yano, Junki*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
no journal, ,
no abstracts in English
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Ishida, Tsuyoshi; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
no journal, ,
We have reported that radon inhalation inhibits oxidative induced damages in some mouse organs due to activation of antioxidant functions. These activations are probably induced by reactive oxygen species following radon inhalation. In this study, we assayed the production of hydrogen peroxide and antioxidant associated substances in brain, lung, heart, liver, stomach, pancreas, kidney, small intestine, and colon in mouse after radon inhalation (1,000 or 10,000 Bq/m for 24 hours). Results showed that radon inhalation significantly decreased LPO levels in liver (1,000 Bq/m and 10,000 Bq/m) and heart (1,000 Bq/m), suggesting that radon inhalation inhibits oxidative stress. However, On the other hand, radon inhalation at a concentration of 10,000 Bq/m significantly increased the levels of LPO and hydrogen peroxide in lungs only. These findings suggested that radon inhalation at high concentration does not induce oxidative stress in other organs except lung.
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Shuto, Hina*; Yano, Junki*; Ishida, Tsuyoshi*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
no journal, ,
no abstracts in English
Kataoka, Takahiro*; Kanzaki, Norie; Sakoda, Akihiro; Shuto, Hina*; Yano, Junki*; Naoe, Shota*; Tanaka, Hiroshi; Hanamoto, Katsumi*; Terato, Hiroaki*; Mitsunobu, Fumihiro*; et al.
no journal, ,
no abstracts in English
Masukawa, Yuki*; Kataoka, Takahiro*; Shuto, Hina*; Naoe, Shota*; Yano, Junki*; Kanzaki, Norie; Sakoda, Akihiro; Tanaka, Hiroshi; Hanamoto, Katsumi*; Mitsunobu, Fumihiro*; et al.
no journal, ,
no abstracts in English
