Kobashi, Yusuke*; Kataoka, Takahiro*; Kanzaki, Norie; Ishida, Tsuyoshi*; Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Radiation and Environmental Biophysics, 59(3), p.473 - 482, 2020/08
Radon therapy has been traditionally performed globally for oxidative stress-related diseases. Many researchers have studied the beneficial effects of radon exposure in living organisms. However, the effects of thoron, a radioisotope of radon, have not been fully examined. In this study, we aimed to compare the biological effects of radon and thoron inhalation on mouse organs with a focus on oxidative stress. Male BALB/c mice were randomly divided into 15 groups: sham inhalation, radon inhalation at a dose of 500 Bq/m or 2000 Bq/m, and thoron inhalation at a dose of 500 Bq/m or 2000 Bq/m were carried out. Immediately after inhalation, mouse tissues were excised for biochemical assays. The results showed a significant increase in superoxide dismutase and total glutathione, and a significant decrease in lipid peroxide following thoron inhalation under several conditions. Additionally, similar effects were observed for different doses and inhalation times between radon and thoron. Our results suggest that thoron inhalation also exerts antioxidative effects against oxidative stress in organs. However, the inhalation conditions should be carefully analyzed because of the differences in physical characteristics between radon and thoron.
Sakoda, Akihiro; Murakami, Shoichi*; Ishimori, Yuu; Horai, Sawako*
Journal of Radiation Research (Internet), 61(2), p.207 - 213, 2020/03
Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Shimomura, Koichiro*
Applied Physics Letters, 115(19), p.192103_1 - 192103_4, 2019/11
Sakoda, Akihiro; Kono, Takahiko; Kataoka, Noriaki*; Andresz, S.*
Hoken Butsuri (Internet), 54(3), p.181 - 187, 2019/10
no abstracts in English
Iida, Kazuki*; Yoshida, Hiroyuki*; Okabe, Hirotaka*; Katayama, Naoyuki*; Ishii, Yuto*; Koda, Akihiro*; Inamura, Yasuhiro; Murai, Naoki; Ishikado, Motoyuki*; Kadono, Ryosuke*; et al.
Scientific Reports (Internet), 9(1), p.1826_1 - 1826_9, 2019/02
Kono, Takahiko; Tanaka, Masato*; Sakoda, Akihiro; Tanaka, Hitomi*; Takeuchi, Masato*; Kataoka, Noriaki*
Proceedings of World Engineers Convention Australia 2019 (WEC 2019) (Internet), p.486 - 496, 2019/00
Sakoda, Akihiro; Okazaki, Toru*; Hashizume, Takuya*
Hoken Butsuri (Internet), 53(3), p.197 - 200, 2018/09
This article gives the report on participation in the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5), which was held in Melbourne, Australia on between May 20th and 23rd, 2018.
Hoeikyo Nyusu, (96), p.9 - 10, 2018/07
This article gives the report on the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5), which was held in Melbourne, Australia on between May 20th and 23rd, 2018.
Sakoda, Akihiro; Nakatsuka, Yoshiaki; Ishimori, Yuu; Nakashima, Shinichi; Komeda, Masao; Ozu, Akira; Toh, Yosuke
Journal of Nuclear Science and Technology, 55(6), p.605 - 613, 2018/06
For better nuclear material accountancy, we had developed a non-destructive assay system dedicated to uranium waste drums (JAWAS-N: JAEA Waste Assay System at Ningyo-toge). The system is based on a fast neutron direct interrogation (FNDI) method. To clarify the characteristics of the FNDI method and the performance of JAWAS-N, experimental and computational mock-up tests were carried out using various dry materials that contained known amounts of natural uranium. As a result, linearity between the die-away time () and the counts of fast neutrons attributed to U fission was confirmed experimentally and analytically. Moreover, the MCNP simulation was performed to discuss the radial and axial dependences of U fission probability, neutron detection efficiency, and sensitivity on uranium distributions in the drum. The simulation results agreed with the empirical results reported in a previous paper, providing valuable information on the practice of FNDI-based uranium determination. Furthermore, the nominal detection limits of natural uranium in JAWAS-N were estimated to be 15, 4, and 2 g for = 0.2, 0.3, and 0.4 msec, respectively. The findings obtained here will contribute to the implementation of the FNDI method to assess the quantities of U in actual uranium waste drums.
Sasaoka, Kaori*; Kataoka, Takahiro*; Kanzaki, Norie; Kobashi, Yusuke*; Sakoda, Akihiro; Ishimori, Yuu; Yamaoka, Kiyonori*
Pakistan Journal of Zoology, 50(3), p.1157 - 1170, 2018/06
Cisplatin (CDDP) is widely used for treating solid cancers; however, it induces nephrotoxicity caused by oxidative stress. Here, we investigated whether radon inhalation has different effects against CDDP induced renal injury in two mouse strains differing in radiosensitivity, and determined the appropriate dose of CDDP combined with radon inhalation for highly radiosensitive mice. CDDP was administered at 20 mg/kg weight to C57BL/6J and BALB/c mice after radon inhalation at 1000 Bq/m and 2000 Bq/m for 24 h. Radon inhalation had a slight positive effect against CDDP toxicity in C57BL/6J mice with respect to improved hair condition, whereas radon inhalation exacerbated CDDP-induced toxicity in BALB/c mice. When BALB/c mice were treated with a lower dose of CDDP (15 mg/kg) after 1000 Bq/m radon inhalation, the creatinine level was reduced and the superoxide dismutase content was increased. The supportive effect of radon inhalation shows its good potential as a candidate treatment to alleviate CDDP-induced renal damage.
Kawamura, Seiko; Tomiyasu, Keisuke*; Koda, Akihiro*; Sari, D. P.*; Asih, R.*; Yoon, S.*; Watanabe, Isao*; Nakajima, Kenji
JPS Conference Proceedings (Internet), 21, p.011007_1 - 011007_5, 2018/03
RbCuMoO is a one-dimensional quantum spin system with spin frustration. The magnetic ground state of this system has been expected to be incommensurate spin-singlet from a theoretical study. Furthermore, it was recently reported that this system exhibited ferroelectricity under a magnetic field. We carried out SR studies on this system to understand the magnetic properties. A slow muon spin relaxation due to nuclear dipoles is observed in the whole measured temperatures ranging from 0.06 K to 250 K, indicating that no magnetic ordering. The result suggests that the system shows a spin-singlet ground state. Furthermore, it was found that the distribution of the internal magnetic field were slightly enhanced below 10 K. This temperature dependence resembles that of the electric polarization observed in the magnetic field. It may indicate that some local anomaly of charge/spin related to the ferroelectricity is detected by a microscopic probe.
Kanzaki, Norie; Kataoka, Takahiro*; Kobashi, Yusuke*; Yunoki, Yuto*; Ishida, Tsuyoshi*; Sakoda, Akihiro; Ishimori, Yuu; Yamaoka, Kiyonori*
Radioisotopes, 67(2), p.43 - 57, 2018/02
We previously reported that low-dose radiation induces the anti-oxidative function in many organ systems of mice. This results in the suppression of several kinds of oxidative stress-induced damage. This study was conducted with the objective of revealing the health effects of low-dose radiation obtained from our previous reports and searching for a new treatment based on low-dose radiation, such as radon therapy. We extracted the characteristics of the effects of low dose radiation suppressing diseases and enhancing the anti-oxidative function using fuzzy answer by self-organizing map (SOM) based on mutual knowledge. The relationship between the suppressive effect and increased antioxidative function was shown in our result, and the concentration dependence of the effect against pain was shown on the output map. Although the effect against other organs depending on concentration was unpredictable, our results indicate that low-dose radiation may also be suitable for treatment of liver disease and brain disease.
Sakoda, Akihiro; Ishimori, Yuu
Hoken Butsuri, 52(4), p.296 - 306, 2017/12
Radon emanation means the escape of radon atoms from solid grains into pore space; it is the very first process that may lead to radon exposure in the environment. Experimental and numerical studies of radon emanation have been diligently carried out since its recognition as a carcinogen. Our previous review of the measured data showed a wide range of radon emanation fractions from natural substances, and then we discussed the effects of environmental factors such as pore water. The present paper provides an overview of the approaches and progress of radon emanation modeling that may be useful for the interpretation of measured data. Recoil and/or diffusion of radon in solid following alpha decay of radium, which underlies the mechanisms of radon emanation, have been incorporated into numerical models. In the calculation based on recoil-based emanation, radium distribution and pore size were the most important parameters, which govern the magnitudes of radon ejections from the birth grain and of radon embedding into another solid surface, respectively. The solid diffusion appeared significant only at a temperature higher than a few hundred degrees Celsius. A model is now desired to be developed that incorporates the transport process of radon atoms that are still settled in solid after alpha recoil, considering radiation damage and its resulting inner path network.
Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Higemoto, Wataru; Kadono, Ryosuke*; Kawamura, Naritoshi*; Koda, Akihiro*; Kojima, Kenji*; Makimura, Shunsuke*; Matoba, Shiro*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Strasser, P.*
Quantum Beam Science (Internet), 1(1), p.11_1 - 11_24, 2017/06
A muon experimental facility, known as the Muon Science Establishment (MUSE), is one of the user facilities at the Japan Proton Accelerator Research Complex, along with those for neutrons, hadrons, and neutrinos. The MUSE facility is integrated into the Materials and Life Science Facility building in which a high-energy proton beam that is shared with a neutron experiment facility delivers a variety of muon beams for research covering diverse scientific fields. In this review, we present the current status of MUSE, which is still in the process of being developed into its fully fledged form.
Etani, Reo*; Kataoka, Takahiro*; Kanzaki, Norie*; Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu; Mitsunobu, Fumihiro*; Taguchi, Takehito*; Yamaoka, Kiyonori*
Journal of Radiation Research, 58(5), p.614 - 625, 2017/05
Radon therapy using radon (Rn) gas is classified into two types of treatment: inhalation of radon gas and drinking water containing radon. Although short- or long-term intake of spa water is effective in increasing gastric mucosal blood flow, and spa water therapy is useful for treating chronic gastritis and gastric ulcer, the underlying mechanisms for and precise effects of radon protection against mucosal injury are unclear. In the present study, we examined the protective effects of hot spring water drinking and radon inhalation on ethanol-induced gastric mucosal injury in mice. Mice inhaled radon at a concentration of 2000 Be/m for 24 h or were provided with hot spring water for 2 weeks. The activity density of Rn ranged from 663 Bq/l (start point of supplying) to 100 Bq/l (end point of supplying).Mice were then orally administered ethanol at three concentrations. The ulcer index (UI), an indicator of mucosal injury, increased in response to the administration of ethanol; however, treatment with either radon inhalation or hot spring water inhibited the elevation in the UI due to ethanol. Although no significant differences in antioxidative enzymes were observed between the radon-treated groups and the non-treated control groups, lipid peroxide levels were significantly lower in the stomachs of mice pre-treated with radon or hot spring water. These results suggest that hot spring water drinking and radon inhalation inhibit ethanol-induced gastric mucosal injury.
Ishimori, Yuu; Tanaka, Hiroshi; Sakoda, Akihiro; Kataoka, Takahiro*; Yamaoka, Kiyonori*; Mitsunobu, Fumihiro*
Radiation and Environmental Biophysics, 56(2), p.161 - 165, 2017/05
In order to investigate the biokinetics of inhaled radon, radon concentrations in mouse tissues and organs were determined after mice had been exposed to about 1 MBq/m of radon in air. Radon concentrations in mouse blood and in other tissues and organs were measured with a liquid scintillation counter and with a well-type HP Ge detector, respectively. Radon concentration in mouse blood was 0.4100.016 Bq/g when saturated with 1 MBq/m of radon concentration in air. In addition, average partition coefficients obtained were 0.740.19 for liver, 0.460.13 for muscle, 9.090.49 for adipose tissue, and 0.220.04 for other organs. With these results, a value of 0.414 for the blood-to-air partition coefficient was calculated by means of our physiologically based pharmacokinetic model. The time variation of radon concentration in mouse blood during exposure to radon was also calculated. All results are compared in detail with those found in the literature.
Ishimori, Yuu; Yokoyama, Kaoru*; Hayakawa, Tomoya; Hata, Haruhi; Sakoda, Akihiro; Naganuma, Masaki
Dekomisshoningu Giho, (55), p.36 - 44, 2017/03
This paper gives an outline of the current status of uranium measurements and their related techniques at the Ningyo-toge Environmental Engineering Center of Japan Atomic Energy Agency. The JAWAS-N and the Q system have been adopted to evaluate uranium contents in the wastes. About 10 g or more of uranium in a 200 drum can be evaluated by these systems. The equivalent model developed to correct the evaluation results with Q system is not available to less than dozens of grams of uranium in a 200 L drum. The paper illustrates the advantage of use of the improved equivalent model which evaluates uranium content from full energy peak of 1001 keV and its Compton spectrum in order to correct the inhomogeneous distribution of uranium in measuring objects. The use of model achieved the limit of uranium quantitative determination under one tenth of those of previous evaluation methods. To determine U, it was demonstrated that the shielding factor, for evaluation of 1001 keV -ray is also possible to use for evaluation of 186 keV -ray. The measurement systems adopting the model have been introduced to other nuclear operators in Japan. In addition, it is also examined to use for clearance. As a related technique, feasibility studies on machine learning algorithms have been performed to classify the waste drums depending on their -ray spectrum.
Ito, Takashi; Koda, Akihiro*; Shimomura, Koichiro*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Kobayashi, Yoji*; Kageyama, Hiroshi*
Physical Review B, 95(2), p.020301_1 - 020301_5, 2017/01
Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu
Hoken Butsuri, 51(4), p.245 - 250, 2016/12
In the present work, the natural -ray background was thoroughly measured using a high-purity germanium detector in a year (283.5 days in total, = 271). The data was first discussed in relation to radon concentrations in the laboratory. No correlations were found between the -ray count rates from Pb and Bi and radon concentrations, meaning that radon just around the germanium detector was reduced to the negligible level by the introduction of nitrogen gas. Also, the count rates of major nuclides appeared to fluctuate with the coefficient of variance of a few up to several tens of percent, without seasonal variations. Furthermore, summing of all -ray spectra allowed us to see neutron-induced peaks that cannot be detected in usual short-term measurements. All data obtained here would be the knowledge useful for the practice of -ray measurements.