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Journal Articles

Comparison of antioxidative effects between radon and thoron inhalation in mouse organs

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

 Times Cited Count:1 Percentile:100(Biology)

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$$^{3}$$ or 2000 Bq/m$$^{3}$$, and thoron inhalation at a dose of 500 Bq/m$$^{3}$$ or 2000 Bq/m$$^{3}$$ 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.

Journal Articles

Concentration ratios of $$^{238}$$U and $$^{226}$$Ra for insects and amphibians living in the vicinity of the closed uranium mine at Ningyo-toge, Japan

Sakoda, Akihiro; Murakami, Shoichi*; Ishimori, Yuu; Horai, Sawako*

Journal of Radiation Research (Internet), 61(2), p.207 - 213, 2020/03

 Times Cited Count:0 Percentile:100(Biology)

Journal Articles

Establishment and activities of Young Generation Network (IRPA YGN) in International Radiation Protection Association

Sakoda, Akihiro; Kono, Takahiko; Kataoka, Noriaki*; Andresz, S.*

Hoken Butsuri (Internet), 54(3), p.181 - 187, 2019/10

no abstracts in English

Journal Articles

Lessons learned from the risk communication with the public after the Fukushima Daiichi Nuclear Power Plant accident

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

Journal Articles

Report on participation in the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5)

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.

Journal Articles

Report on the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5)

Sakoda, Akihiro

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.

Journal Articles

Production and detection of fission-induced neutrons following fast neutron direct interrogation to various dry materials containing $$^{235}$$U

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

 Times Cited Count:1 Percentile:74.25(Nuclear Science & Technology)

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 ($$tau$$$$_{2}$$) and the counts of fast neutrons attributed to $$^{235}$$U fission was confirmed experimentally and analytically. Moreover, the MCNP simulation was performed to discuss the radial and axial dependences of $$^{235}$$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 $$tau$$$$_{2}$$ = 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 $$^{235}$$U in actual uranium waste drums.

Journal Articles

Comparative effects of radon inhalation according to mouse strain and cisplatin dose in a cisplatin-induced renal damage model

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

 Times Cited Count:1 Percentile:73.98(Zoology)

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$$^{3}$$ and 2000 Bq/m$$^{3}$$ 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$$^{3}$$ 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.

Journal Articles

Knowledge discovery of suppressive effect of disease and increased anti-oxidative function by low-dose radiation using self-organizing map

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.

Journal Articles

Mechanisms and modeling approaches of radon emanation for natural materials

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.

Journal Articles

Protective effects of hot spring water drinking and radon inhalation on ethanol-induced gastric mucosal injury in mice

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

 Times Cited Count:2 Percentile:73.23(Biology)

Radon therapy using radon ($$^{222}$$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$$^{3}$$ for 24 h or were provided with hot spring water for 2 weeks. The activity density of $$^{222}$$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.

Journal Articles

Measurements of radon activity concentration in mouse tissues and organs

Ishimori, Yuu; Tanaka, Hiroshi; Sakoda, Akihiro; Kataoka, Takahiro*; Yamaoka, Kiyonori*; Mitsunobu, Fumihiro*

Radiation and Environmental Biophysics, 56(2), p.161 - 165, 2017/05

 Times Cited Count:4 Percentile:64.02(Biology)

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$$^{3}$$ 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 0.410$$pm$$0.016 Bq/g when saturated with 1 MBq/m$$^{3}$$ of radon concentration in air. In addition, average partition coefficients obtained were 0.74$$pm$$0.19 for liver, 0.46$$pm$$0.13 for muscle, 9.09$$pm$$0.49 for adipose tissue, and 0.22$$pm$$0.04 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.

Journal Articles

Current status of uranium measurements and their related techniques at JAEA Ningyo-toge

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$$^2$$ system have been adopted to evaluate uranium contents in the wastes. About 10 g or more of uranium in a 200 $$ell$$ drum can be evaluated by these systems. The equivalent model developed to correct the evaluation results with Q$$^2$$ 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 $$^{235}$$U, it was demonstrated that the shielding factor, $$X_{geometry}$$ for evaluation of 1001 keV $$gamma$$-ray is also possible to use for evaluation of 186 keV $$gamma$$-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 $$gamma$$-ray spectrum.

Journal Articles

One-year measurements of $$gamma$$-ray background using a high-purity germanium detector

Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu

Hoken Butsuri, 51(4), p.245 - 250, 2016/12

In the present work, the natural $$gamma$$-ray background was thoroughly measured using a high-purity germanium detector in a year (283.5 days in total, $$n$$ = 271). The data was first discussed in relation to radon concentrations in the laboratory. No correlations were found between the $$gamma$$-ray count rates from $$^{214}$$Pb and $$^{214}$$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 $$gamma$$-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 $$gamma$$-ray measurements.

Journal Articles

Report on participation in the 14th International Congress of the International Radiation Protection Association (IRPA-14)

Sakoda, Akihiro; Matsumoto, Shinnosuke*

Hoken Butsuri, 51(3), p.187 - 190, 2016/09

This article gives the report on participation in 14th International Congress of the International Radiation Protection Association (IRPA-14), which was held in Cape Town, South Africa on between May 9th and 13th, 2016.

Journal Articles

Report on recent meetings of the young researchers association and the students association of the Japan Health Physics Society

Sakoda, Akihiro; Kataoka, Noriaki*; Ueno, Satoshi*; Matsuyama, Tsugufumi*

Hoken Butsuri, 51(3), p.191 - 195, 2016/09

This article briefly overviews two recent meetings (December 2015 and July 2016) of the Young Researchers Association and the Students Association of the Japan Health Physics Society.

Journal Articles

Report on special sessions in the 49th Annual Meeting of the Japan Health Physics Society

Sakoda, Akihiro; Kataoka, Noriaki*; Ishikawa, Junya*; Ota, Akio*; Suzuki, Tatsuhiko*; Nishiyama, Yuichi*; Hirouchi, Jun; Hokama, Tomonori

Hoken Butsuri, 51(3), p.181 - 186, 2016/09

The 49th annual meeting of the Japan Health Physics Society was held in Hirosaki, Aomori between June 30th and July 1st, 2016. This article gives the report on all of twelve special sessions in this meeting.

Journal Articles

Evaluation of the intake of radon through skin from thermal water

Sakoda, Akihiro; Ishimori, Yuu; Tschiersch, J.*

Journal of Radiation Research, 57(4), p.336 - 342, 2016/07

 Times Cited Count:4 Percentile:71.76(Biology)

In general, the deposition of inhaled radon progeny on lung gives the largest dose when the dose evaluation is made for the so-called radon exposure. In this case, the dose from inhalation of radon itself is much lower than that from its progeny. Also, very little studies of the absorption of radon via skin have not been done so far. However, specific environments such as radon hot springs have the characteristics that radon concentration in water is significantly higher by a few orders than that in air. In the present study, a biokinetic model of radon into which its skin-absorption process was incorporated was developed to discuss the change in radon concentrations in tissues during and after bathing in thermal water. This derived dose was compared with other exposure routes from radon and its progeny.

Journal Articles

Analysis of variations in observed ambient dose rates due to rainfall or snowfall at JAEA Ningyo-toge

Tanaka, Hiroshi; Sakoda, Akihiro; Ando, Masaki; Ishimori, Yuu

Hoken Butsuri, 51(2), p.107 - 114, 2016/06

Ambient dose rates are continuously monitored in Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency. The present study discussed the variations in ambient dose rates, observed from April 2014 to March 2015, due to snowfall as well as rainfall. It is much snowy as one of climatic features in this area. Rain or snow was sampled for a certain period in the day of interest (17 cases in total), and then the concentration of radon progeny was measured. With the measured data, the variation in ambient dose rate was calculated considering the accumulation of the radon progeny on the ground. As a whole, this calculation was found to reasonably reproduce the time trends of observed dose rates, except for four cases. Based on the backward trajectory analysis, it was explained that the discrepancy in two cases out of the four was induced by changes of radon progeny concentration in precipitation around sampling period. It was suggested that the other two cases were caused by the run-off of rain from the ground surface.

Journal Articles

Difference in the action mechanism of radon inhalation and radon hot spring water drinking in suppression of hyperuricemia in mice

Etani, Reo*; Kataoka, Takahiro*; Kanzaki, Norie*; Sakoda, Akihiro; Tanaka, Hiroshi; Ishimori, Yuu; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*

Journal of Radiation Research, 57(3), p.250 - 257, 2016/06

 Times Cited Count:5 Percentile:57.48(Biology)

Although radon therapy is indicated for hyperuricemia, the underlying mechanisms of action have not yet been elucidated in detail. Therefore, we herein examined the inhibitory effects of radon inhalation and hot spring water drinking on potassium oxonate (PO)-induced hyperuricemia in mice. After mice inhaled radon at a concentration of 2000 Bq/m$$^{3}$$ for 24 h or were given hot spring water for 2 weeks, they were administrated PO. Radon inhalation or hot spring water drinking significantly inhibited elevations in serum uric acid levels through the suppression of xanthine oxidase activity in the liver. Radon inhalation activated anti-oxidative functions in the liver and kidney. These results suggest that radon inhalation inhibits PO-induced hyperuricemia by activating anti-oxidative functions, while hot spring water drinking may suppress PO-induced elevations in serum uric acid levels through the pharmacological effects of the chemical compositions dissolved in it.

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