Publishing type：Research paper (scientific journal)   Publisher：The Society for Free Radical Research Japan  

DOI： 10.3164/jcbn.21-85

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Publishing type：Research paper (scientific journal)   Publisher：The Society for Free Radical Research Japan  

DOI： 10.3164/jcbn.21-91

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
Radon inhalation decreases the level of lipid peroxide (LPO); this is attributed to the activation of antioxidative functions. This activation contributes to the beneficial effects of radon therapy, but there are no studies on the risks of radon therapy, such as DNA damage. We evaluated the effect of radon inhalation on DNA damage caused by oxidative stress and explored the underlying mechanisms. Mice were exposed to radon inhalation at concentrations of 2 or 20 kBq/m3 (for one, three, or 10 days). The 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels decreased in the brains of mice that inhaled 20 kBq/m3 radon for three days and in the kidneys of mice that inhaled 2 or 20 kBq/m3 radon for one, three or 10 days. The 8-OHdG levels in the small intestine decreased by approximately 20–40% (2 kBq/m3 for three days or 20 kBq/m3 for one, three or 10 days), but there were no significant differences in the 8-OHdG levels between mice that inhaled a sham treatment and those that inhaled radon. There was no significant change in the levels of 8-oxoguanine DNA glycosylase, which plays an important role in DNA repair. However, the level of Mn-superoxide dismutase (SOD) increased by 15–60% and 15–45% in the small intestine and kidney, respectively, following radon inhalation. These results suggest that Mn-SOD probably plays an important role in the inhibition of oxidative DNA damage.

DOI： 10.1093/jrr/rrab069

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
It is held that the skin dose from radon progeny is not negligibly small and that introducing cancer is a possible consequence under normal circumstances as there are a number of uncertainties in terms of related parameters such as activity concentrations in air and water, target cells in skin, skin covering materials, and deposition velocities. An interesting proposal has emerged in that skin exposure to natural radon-rich thermal water as part of balneotherapy can produce an immune response to induce beneficial health effects. The goal of this study was to obtain generic dose coefficients with a focus on the radon progeny deposited on the skin in air or water in relation to risk or treatment assessments. We thus first estimated the skin deposition velocities of radon progeny in air and thermal water based on data from the latest human studies. Skin dosimetry was then performed under different assumptions regarding alpha-emitting source position and target cell (i.e. basal cells or Langerhans cells). Furthermore, the impact of the radon progeny deposition on effective doses from all exposure pathways relating to ‘radon exposure’ was assessed using various possible scenarios. It was found that in both exposure media, effective doses from radon progeny inhalation are one to four orders of magnitude higher than those from the other pathways. In addition, absorbed doses on the skin can be the highest among all pathways when the radon activity concentrations in water are two or more orders of magnitude higher than those in air.

DOI： 10.1093/jrr/rrab030

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Language：English   Publishing type：Research paper (scientific journal)  

The forced swim test (FST) induces immobility in mice. Low-dose (high-dose-rate) X-irradiation inhibits FSTinduced immobility in mice due to its antioxidative function. We evaluated the effects of low-dose γ-irradiation at a low-dose-rate on the FST-induced depletion of antioxidants in mouse organs. Mice received whole-body low-dose-rate (0.6 or 3.0 mGy/h) of low-dose γ-irradiation for 1 week, followed by daily FSTs (5 days). The immobility rate on day 2 compared to day 1 was significantly lower in the 3.0 mGy/h irradiated mice than in sham irradiated mice. The FST significantly decreased the catalase (CAT) activity and total glutathione (t-GSH) content in the brain and kidney, respectively. The superoxide dismutase (SOD) activity and t-GSH content in the liver of the 3.0 mGy/h irradiated mice were significantly lower than those of the non-FST-treated mice. The CAT activity in the lungs of mice exposed to 3.0 mGy/h γ-irradiation was higher than that of non-FST treated mice and mice treated with FST. However, no significant differences were observed in the levels of these antioxidant markers between the sham and irradiated groups except for the CAT activity in lungs. These findings suggest that the effects of low-dose-rate and low-dose γ-irradiation on FST are highly organ-dependent.

DOI： 10.18926/AMO/61896

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
Radon inhalation activates antioxidative functions in mouse organs, thereby contributing to inhibition of oxidative stress-induced damage. However, the specific redox state of each organ after radon inhalation has not been reported. Therefore, in this study, we evaluated the redox state of various organs in mice following radon inhalation at concentrations of 2 or 20 kBq/m3 for 1, 3 or 10 days. Scatter plots were used to evaluate the relationship between antioxidative function and oxidative stress by principal component analysis (PCA) of data from control mice subjected to sham inhalation. The results of principal component (PC) 1 showed that the liver and kidney had high antioxidant capacity; the results of PC2 showed that the brain, pancreas and stomach had low antioxidant capacities and low lipid peroxide (LPO) content, whereas the lungs, heart, small intestine and large intestine had high LPO content but low antioxidant capacities. Furthermore, using the PCA of each obtained cluster, we observed altered correlation coefficients related to glutathione, hydrogen peroxide and LPO for all groups following radon inhalation. Correlation coefficients related to superoxide dismutase in organs with a low antioxidant capacity were also changed. These findings suggested that radon inhalation could alter the redox state in organs; however, its characteristics were dependent on the total antioxidant capacity of the organs as well as the radon concentration and inhalation time. The insights obtained from this study could be useful for developing therapeutic strategies targeting individual organs.

DOI： 10.1093/jrr/rraa129

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

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/m3 or 2000 Bq/m3, and thoron inhalation at a dose of 500 Bq/m3 or 2000 Bq/m3 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.

DOI： 10.1007/s00411-020-00843-0

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Other Link： http://link.springer.com/article/10.1007/s00411-020-00843-0/fulltext.html

Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
The forced swim test (FST) is a screening model for antidepressant activity; it causes immobility and induces oxidative stress. We previously reported that radon inhalation has antidepressant-like effects in mice potentially through the activation of antioxidative functions upon radon inhalation. This study aimed to investigate the effect of prior and post low-dose X-irradiation (0.1, 0.5, 1.0 and 2.0 Gy) on FST-induced immobility and oxidative stress in the mouse brain, and the differences, if any, between the two. Mice received X-irradiation before or after the FST repeatedly for 5 days. In the post-FST-irradiated group, an additional FST was conducted 4 h after the last irradiation. Consequently, animals receiving prior X-irradiation (0.1 Gy) had better mobility outcomes than sham-irradiated mice; however, their levels of lipid peroxide (LPO), an oxidative stress marker, remained unchanged. However, animals that received post-FST X-irradiation (0.5 Gy) had better mobility outcomes and their LPO levels were significantly lower than those of the sham-irradiated mice. The present results indicate that 0.5 Gy X-irradiation after FST inhibits FST-induced immobility and oxidative stress in mice.

DOI： 10.1093/jrr/rraa022

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Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.69.45

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ZOOLOGICAL SOC PAKISTAN  

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, such as a decrease in hair condition, higher creatinine levels, and decreased antioxidant contents (catalase and glutathione). 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, suggesting that this combination might have a protective effect against the CDDP-induced renal damage. The supportive effect of radon inhalation shows its good potential as a candidate treatment to alleviate CDDP-induced renal damage in veterinary medicine.

DOI： 10.17582/journal.pjz/2018.50.3.1157.1170

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

The energy spectra of X-rays produced by an LiTaO3 single crystal have been measured at the pressures of 8 × 10−4−4 Pa. The energy spectra showed that the endpoint energy steadily increased with decrease of pressure at 2–4 Pa and gradually decreased with decrease of pressure at 0.1–2 Pa, and became almost constant below 0.1 Pa. The amount of X-rays steadily increased with decrease of pressure at 2–4 Pa and almost saturated below 0.5 Pa. The change of X-rays produced by the LiTaO3 single crystal was compared with the previous works and discussed in relation to the distance between the crystal surface and the target.

DOI： 10.1016/j.apradiso.2018.01.019

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DOI： 10.3769/radioisotopes.67.43

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press  

Although radon inhalation increases superoxide dismutase (SOD) activities in mouse organs, the mechanisms and pathways have not yet been fully clarified. The aim of this study was to determine the details of SOD activation in mouse brain tissue following the inhalation of radon at concentrations of 500 or 2000 Bq/m3 for 24 h. After inhalation, brains were removed quickly for analysis. Radon inhalation increased the manganese (Mn)- SOD level and mitochondrial SOD activity. However, the differences were not significant. There were no changes in the Cu/Zn-SOD level or cytosolic SOD activity. Radon inhalation increased the brain nuclear factor (NF)-κB content, which regulates the induction of Mn-SOD, in the nuclear and cytosolic compartments. The level of inhibitor of nuclear factor κB kinase subunit β (IKK-β), which activates NF-κB, was slightly increased by radon inhalation. The expression of cytoplasmic ataxia-telangiectasia mutated kinase in mice inhaling radon at 500 Bq/m3 was 50% higher than in control mice. In addition, NF-κB-inducing kinase was slightly increased after inhaling radon at 2000 Bq/m3. These findings suggest that radon inhalation might induce Mn-SOD protein via NF-κB activation that occurs in response to DNA damage and oxidative stress.

DOI： 10.1093/jrr/rrx048

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Radon therapy using radon (Rn-222) 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 Bq/m(3) for 24 h or were provided with hot spring water for 2 weeks. The activity density of Rn-222 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.

DOI： 10.1093/jrr/rrx021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The purpose of this study is to investigate the biokinetics of inhaled radon, radon activity concentrations in mouse tissues and organs were determined after mice had been exposed to about 1 MBq/m(3) of radon in air. Radon activity 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 activity concentration in mouse blood was 0.410 +/- 0.016 Bq/g when saturated with 1 MBq/m(3) of radon activity concentration in air. In addition, average partition coefficients obtained were 0.74 +/- 0.19 for liver, 0.46 +/- 0.13 for muscle, 9.09 +/- 0.49 for adipose tissue, and 0.22 +/- 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 activity concentration in mouse blood during exposure to radon was also calculated. All results are compared in detail with those found in the literature.

DOI： 10.1007/s00411-017-0682-9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

In our previous studies, we found that low-dose radiation inhibits oxidative stress-induced diseases due to increased antioxidants. Although these effects of low-dose radiation were demonstrated, further research was needed to clarify the effects. However, the analysis of oxidative stress is challenging, especially that of low levels of oxidative stress, because antioxidative substances are intricately involved. Thus, we proposed an approach for analysing oxidative liver damage via use of a self-organizing map (SOM)-a novel and comprehensive technique for evaluating hepatic and antioxidative function. Mice were treated with radon inhalation, irradiated with X-rays, or subjected to intraperitoneal injection of alcohol. We evaluated the oxidative damage levels in the liver from the SOM results for hepatic function and antioxidative substances. The results showed that the effects of low-dose irradiation (radon inhalation at a concentration of up to 2000 Bq/m(3), or X-irradiation at a dose of up to 2.0 Gy) were comparable with the effect of alcohol administration at 0.5 g/kg bodyweight. Analysis using the SOM to discriminate small changes was made possible by its ability to 'learn' to adapt to unexpected changes. Moreover, when using a spherical SOM, the method comprehensively examined liver damage by radon, X-ray, and alcohol. We found that the types of liver damage caused by radon, X-rays, and alcohol have different characteristics. Therefore, our approaches would be useful as a method for evaluating oxidative liver damage caused by radon, X-rays and alcohol.

DOI： 10.1093/jrr/rrw083

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The energy spectra of X-rays produced by an LiTaO3 single crystal have been measured at pressures of 1-20 Pa. The energy spectra showed that the endpoint energy and the amount of X-rays gradually increased with the decrease of pressure at 5-8 Pa and abruptly increased around 4 Pa and below. A maximum endpoint energy of 70 keV was obtained using the LiTaO3 single crystal with 5 mm thickness at a pressure of 3 Pa. The change of X-rays produced by the LiTaO(3)single crystal was discussed in relation to the breakdown potential at the pressures. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apradiso.2016.08.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

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. Mice inhaled radon at a concentration of 2000 Bq/m(3) for 24 h or were given hot spring water for 2 weeks. Mice were then administrated PO at a dose of 500 mg/kg. The results obtained showed that serum uric acid levels were significantly increased by the administration of 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.

DOI： 10.1093/jrr/rrw014

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Publishing type：Part of collection (book)  

Oxidative stress in the body is considered an imbalance between the production and removal of reactive oxygen species (ROS). Ischemic acute renal failure, chronic renal failure, uremia, glomerulonephritis, and diabetic nephropathy are ROS-related diseases. In the veterinary field, a few studies of chronic kidney failure related to oxidative stress have been reported. Radon therapy has been used in Japan and Europe, and has been shown to have beneficial effects on ROS-related diseases such as bronchial asthma, arteriosclerosis, osteoarthritis, and pain-related diseases. We have demonstrated that radon inhalation increases antioxidative functions in kidney, and inhibits oxidative stress-induced kidney damage in animals. In addition, radon exposure systems for pets have already been developed. Therefore, we review the possible applications of radon therapy in veterinary care for oxidative stress-induced kidney damage.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

In this study, we compared the protective effects of radon inhalation and ascorbic acid administration on transient global cerebral ischemic injury in gerbils. Gerbils were treated with radon inhalation (2000 Bq/m(3), 24 hours) or ascorbic acid (100, 300, or 500mg/kg body weight). Then, transient global cerebral ischemia was induced by bilateral occlusion of the common carotid artery. Results showed that the number of damaged neurons was significantly increased in gerbils that underwent ischemia compared with that in control gerbils. However, the number of damaged neurons in gerbils treated with radon or 500mg/kg of ascorbic acid before ischemia was significantly lower than gerbils who were subjected to ischemia without any pretreatment, and the protective effects of radon inhalation were similar to the effects of administering 500mg/kg ascorbic acid. The levels of superoxide dismutase (SOD) and total glutathione (t-GSH) in brain tissue were increased to a similar extent by pretreatment with radon inhalation or 500mg/kg of ascorbic acid. These findings suggested that radon inhalation has a protective antioxidative effect against transient global cerebral ischemic injury similar to 500mg/kg ascorbic acid treatment.

DOI： 10.1080/00223131.2016.1198731

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI LTD  

Radon inhalation brings pain relief for chronic constriction injury- (CCI-) induced neuropathic pain in mice due to the activation of antioxidative functions, which is different from the mechanism of the pregabalin effect. In this study, we assessed whether a combination of radon inhalation and pregabalin administration is more effective against neuropathic pain than radon or pregabalin only. Mice were treated with inhaled radon at a concentration of 1,000 Bq/m(3) for 24 hours and pregabalin administration after CCI surgery. In mice treated with pregabalin at a dose of 3 mg/kg weight, the 50% paw withdrawal threshold of mice treated with pregabalin or radon and pregabalin was significantly increased, suggesting pain relief. The therapeutic effects of radon inhalation or the combined effects of radon and pregabalin (3 mg/kg weight) were almost equivalent to treatment with pregabalin at a dose of 1.4 mg/kg weight or 4.1 mg/kg weight, respectively. Radon inhalation and the combination of radon and pregabalin increased antioxidant associated substances in the paw. The antioxidant substances increased much more in radon inhalation than in pregabalin administration. These findings suggested that the activation of antioxidative functions by radon inhalation enhances the pain relief of pregabalin and that this combined effect is probably an additive effect.

DOI： 10.1155/2016/9853692

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

In this study, we investigated the suppressive effects of radon inhalation against nephropathy in C57BL/6J mice with type-1 diabetes induced by intraperitoneal injection of streptozotocin (50 mg/kg weight, given five times). Four weeks after diabetes induction, the diabetic mice were continuously treated with inhaled radon-222 of 2000 Bq/m(3) or air only (sham) for four weeks. The results showed that radon inhalation did not affect type-1 diabetic symptoms such as body weight loss, hyperglycemia, and hypoinsulinemia. However, diabetic mice treated with radon showed lower urinary albumin excretion and fibrotic change in renal glomeruli compared with diabetic mice not treated with radon. Furthermore, renal superoxide dismutase activity and glutathione content were significantly higher in diabetic mice treated with radon than in diabetic mice not treated with radon. These findings suggested that radon inhalation enhanced renal antioxidants activities, resulting in the suppression of diabetic nephropathy. This study may contribute to the development of a novel approach in the treatment of nephropathy for diabetic patients.

DOI： 10.1080/00223131.2015.1078751

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Language：English   Publisher：(公社)日本アイソトープ協会  

雄8〜9週齢ICRマウスを用いて強制水泳試験(FST)を行い、試験により誘導されるうつ病様症状に対するラドン吸入の効果について検証した。マウスの運動機能や不安状態に関してはオープンフィールド試験(OFT)により評価を行い、次に、FST誘導うつ病様症状に対するラドン前処理の効果(予防効果)およびラドン後処理の効果(治療効果)を調べると共に、生化学的検査により、脳内および血中モノアミン類、抗酸化物質の変化を調べた。その結果、予防効果の面では、FST前の2000Bq/m3の24hラドン吸入により、絶望行動が低下し、水泳意欲の向上が観察された。また、治療効果においては、2000Bq/m3の24hラドン吸入により、水泳意欲の向上とうつ病様症状への効果が認められ、水泳ストレスにより、脳内ノルエピネフリンとドーパミンが低下すると共に、FST誘導うつ病状態は血漿中スーパーオキシドジスムターゼ(SOD)活性低下および脳内脂質過酸化物(LPO)含量を増加させることが示された。さらに、ラドン吸入は脳組織内のモノアミン類(セロトニン、ノルエピネフリン、ドーパミン)を増加させると共に、FST前処理においてSOD活性を上昇させ、FST後処理におけるLPO含量を低下させた。以上の結果から、ラドン吸入は、マウス水泳ストレスにより誘導されるうつ病様症状を予防し、抑制することが明らかにされた。

DOI： 10.3769/radioisotopes.65.493

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

It has been reported that radon inhalation activates antioxidative functions in liver and has an antioxidative effect against hepatopathy similar to that of the antioxidative effects of ascorbic acid (VC) or -tocopherol (VE). In this study, we examined the combined effects of radon inhalation and antioxidant vitamin administration on acute alcohol-induced hepatopathy in mice. ICR mice were subjected to intraperitoneal (i.p.) administration of alcohol after pretreating with air only (sham) or radon at a concentration of approximately 2000 Bq/m(3) for 24 hours and i.p. administration of VC (300 mg/kg body weight) or VE (300 mg/kg body weight). In mice injected with alcohol, the combined radon and antioxidant vitamins treatment significantly decreased the activities of glutamic oxaloacetic transaminase in serum compared to not only the alcohol-administered group (sham group), but also the radon inhalation with alcohol administration group or the vitamin and alcohol administration group. In addition, radon inhalation significantly increased the antioxidant level, in such as the catalase activity and the total glutathione content in liver compared to the sham group. These results suggested that the combined radon and antioxidant vitamin treatment could effectively inhibit alcohol-induced hepatopathy in mice without any antagonizing action.

DOI： 10.1080/00223131.2015.1014875

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The possibility of antioxidant therapy has been reported for several diseases such as ischemic stroke. The therapy could also be applied for diseases caused by reactive oxygen species (ROS). It has been reported that ROS or free radicals may cause various types of hepatopathy, including alcoholic liver disease. Low dose (0.5 Gy) X- or γ- irradiation activates the antioxidative functions of the mouse liver and inhibits ROS- or free radical-induced hepatopathy. Radon therapy is performed mainly for pain-related diseases in Japan and Europe. Several clinical studies have been reported, but the possible mechanisms of the beneficial effects remain unknown. Recently, we have reported that the possible mechanism of radon therapy is the activation of antioxidative functions following radon inhalation. For example, radon inhalation inhibits and alleviates chronic constriction injury induced pain or inflammatory pain in mice due to the activation of antioxidative functions. In addition, although hepatopathy is not the main indication for radon therapy, our recent studies suggested that radon inhalation inhibits hepatopathy caused by ROS or free radicals. In this chapter, based on experiments with mice, we reviewed the possible applications of radon inhalation as an antioxidant therapy for hepatopathy from the viewpoints of recent antioxidant therapy, hepatopathy induced by ROS or free radicals, and the beneficial effects of radon inhalation for hepatopathy.

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Language：Japanese   Publisher：(一社)日本温泉科学会  

岡山大学病院三朝医療センターではラドン温泉を活用したラドン療法が実施されており、適応症として例えば変性性関節症に伴う疼痛がある。臨床試験による実証報告例は多くあるものの、なぜ有効であるかのメカニズムの解明に関する研究報告例は少ない。本稿では、放射能効果の観点から近年得られた筆者らのラドン健康効果の研究成果を中心に概説した。すなわち、小動物用ラドン吸入装置を開発し、三朝医療センターに隣接した三朝ラドン効果研究施設内に設置した。これを用い、例えば、マウス諸臓器中の抗酸化酵素活性のラドン濃度・吸入時間の依存性について検討した。その結果、多くの臓器でsuperoxide dismutase(SOD)活性が増加したことから、ラドン吸入は抗酸化機能を亢進させることがわかった。また、streptozotocin(STZ)誘導マウスI型糖尿病の症状緩和について検討した。その結果、ラドン吸入による膵臓中の抗酸化機能の亢進に伴い膵島の酸化ストレスが緩和されることでインスリンの分泌機能の低下が抑制され、I型糖尿病が緩和することもわかった。以上の所見などから、ラドン吸入は抗酸化機能などを亢進させ活性酸素由来の疾患の症状を緩和するメカニズムの一端が明らかにできた。(著者抄録)

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2015&ichushi_jid=J00191&link_issn=&doc_id=20150513080001&doc_link_id=%2Ffd5onsen%2F2015%2F006404%2F003%2F0380-0387%26dl%3D0&url=http%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Ffd5onsen%2F2015%2F006404%2F003%2F0380-0387%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

DOI： 10.14800/ics.601

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

Although brain disorders are not the main indication for radon therapy, our previous study suggested that radon inhalation therapy might mitigate brain disorders. In this study, we assessed whether radon inhalation protects against transient global cerebral ischemic injury in gerbils. Gerbils were treated with inhaled radon at a concentration of 2,000 Bq/m(3) for 24 h. After radon inhalation, transient global cerebral ischemia was induced by bilateral occlusion of the common carotid artery. Results showed that transient global cerebral ischemia induced neuronal damage in hippocampal CA1, and the number of damaged neurons was significantly increased compared with control. However, radon treatment inhibited ischemic damage. Superoxide dismutase (SOD) activity in the radon-treated gerbil brain was significantly higher than that in sham-operated gerbils. These findings suggested that radon inhalation activates antioxidative function, especially SOD, thereby inhibiting transient global cerebral ischemic injury in gerbils.

DOI： 10.1007/s10753-014-9896-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

This paper provides absorbed doses arising from radon gas in air retained in lung airway lumens. Because radon gas exposure experiments often use small animals, the calculation was performed for mice and rats. For reference, the corresponding computations were also done for humans. Assuming that radon concentration in airway lumens is the same as that in the environment, its progeny's production in and clearance from airways were simulated. Absorbed dose rates were obtained for three lung regions and the whole lung, considering that secretory and basal cells are sensitive to radiation. The results showed that absorbed dose rates for all lung regions and whole lung generally increase from mice to rats to humans. For example, the dose rates for the whole lung were 25.4 in mice, 41.7 in rats, and 59.9 pGy (Bq m(-3))(-1) h(-1) in humans. Furthermore, these values were also compared with lung dose rates from two other types of exposures, that is, due to inhalation of radon or its progeny, which were already reported. It was confirmed that the direct inhalation of radon progeny in the natural environment, which is known as a cause of lung cancer, results in the highest dose rates for all species. Based on the present calculations, absorbed dose rates of the whole lung from radon gas were lower by a factor of about 550 (mice), 200 (rats), or 70 (humans) than those from radon progeny inhalation. The calculated dose rate values are comparatively small. Nevertheless, the present study is considered to contribute to our understanding of doses from inhalation of radon and its progeny.

DOI： 10.1007/s00411-013-0478-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Background Radon therapy is clinically useful for the treatment of pain-related diseases. However, there have been no studies regarding the effects of radon inhalation on neuropathic pain. In this study, we aimed to determine whether radon inhalation actually induced a remission of neuropathic pain and improved the quality of life. Methods First, we investigated the antinociceptive effects of radon inhalation in the chronic constriction injury (CCI) model of neuropathic pain. We evaluated pain behaviour in mice before and after CCI surgery, using von Frey test. Pretreated mice received CCI surgery immediately after 24-h inhalation of radon at background (BG) concentration (c. 19Bq/m3), or at a concentration of 1000 or 2000Bq/m3, and post-treated mice inhaled similar levels of radon 2 days after CCI surgery. Results CCI surgery induced mechanical allodynia and hyperalgesia on a plantar surface of mice, as assessed using von Frey test, and 2000Bq/m3 radon inhalation alleviated hyperalgesic conditions 2237% compared to BG level concentration. Concurrently, CCI surgery increased norepinephrine (NE), tumour necrosis factor-alpha (TNF-) and nitric oxide (NO) concentrations in plasma, and leukocyte migration in paws. Furthermore, CCI-induced neuropathy reduced superoxide dismutase (SOD) activity. Treatment with radon inhalation, specifically at a concentration of 2000Bq/m3, produced antinociceptive effects, i.e., lowered plasma TNF-, NE and NO levels and restored SOD activity, as well as pain-related behaviour. Conclusions This study showed that inhalation of 2000Bq/m3 radon prevented and alleviated CCI-induced neuropathic pain in mice.

DOI： 10.1002/j.1532-2149.2012.00210.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

Radon therapy is clinically useful for the treatment of inflammatory diseases. The mechanisms of pain relief remain to be fully elucidated. In this study, we investigated the antinociceptive effects of radon inhalation in a mouse model of formalin-induced inflammatory pain. Immediately, after radon inhalation at a concentration of background level (ca. 19 Bq/m(3)), 1,000 or 2,000 Bq/m(3) for 24 h, 1.35 % formalin (0.5 % formaldehyde in saline, 20 mu l) was subcutaneously injected into the hind paw of mice, and we measured licking response time. Radon inhalation inhibited the second phase of response in formalin test. Formalin administration induced nociception and increased tumor necrosis factor alpha (TNF-alpha) and nitric oxide (NO) levels in serum and leukocyte migration in paws. Concurrently, formalin injection decreased antioxidative functions. Radon inhalation produced antinociceptive effects, i.e., lowered serum TNF-alpha and NO levels, and restored antioxidative functions. The results showed that radon inhalation inhibited formalin-induced inflammatory pain.

DOI： 10.1007/s10753-012-9554-2

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We examined the protective effect of radon inhalation on streptozotocin (STZ)-induced type-1 diabetes in mice. Mice inhaled radon at concentrations of 1000, 2500, and 5500 Bq/m3 for 24 hours before STZ administration. STZ administration induced characteristics of type-1 diabetes such as hyperglycemia and hypoinsulinemia
however, radon inhalation at doses of 1000 and 5500 Bq/m3 significantly suppressed the elevation of blood glucose in diabetic mice. Serum insulin was significantly higher in mice pre-treated with radon at a dose of 1000 Bq/m3 than in mice treated with a sham. In addition, superoxide dismutase activities and total glutathione contents were significantly higher and lipid peroxide was significantly lower in mice pre-treated with radon at doses of 1000 and 5500 Bq/m3 than in mice treated with a sham. These results were consistent with the result that radon inhalation at 1000 and 5500 Bq/m3 suppressed hyperglycemia. These findings suggested that radon inhalation suppressed STZ-induced type-1 diabetes through the enhancement of antioxidative functions in the pancreas. © 2013 Institute of Physiology v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Radon therapy has long been performed for pain- and oxidative-stress- related diseases in Bad Gastein (Austria) and Misasa (Tottori). We carried out some animal experiments to clarify the mechanism underlying the effects of the therapy. The findings indicated that radon inhalation has antioxidative effects. For example, radon inhalation suppressed liver functional disorder and oxidative damage following carbon tetrachloride administration in mice. In addition, the anti-inflammatory effect through the enhancement of the antioxidative function, which suppresses inflammatory pain, was also obtained. From these findings, the possibility of health promotion by radon is suggested. © 2013 Atomic Energy Society of Japan, All Rights Reserved.

DOI： 10.3327/taesj.J13.004

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DOI： 10.1093/jrr/rrs141

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We have previously reported that radon inhalation activates anti-oxidative functions and inhibits carbon tetrachloride (CCl4)-induced hepatopathy. It has also been reported that antioxidant vitamins can inhibit CCl4-induced hepatopathy. In the current study, we examined the comparative efficacy of treatment with radon, ascorbic acid and alpha-tocopherol on CCl4-induced hepatopathy. Mice were subjected to intraperitoneal injection of CCl4 after inhaling approximately 1000 or 2000 Bq/m(3) radon for 24 h, or immediately after intraperitoneal injection of ascorbic acid (100, 300, or 500 mg/kg bodyweight) or alpha-tocopherol (100, 300, or 500 mg/kg bodyweight). We estimated the inhibitory effects on CCl4-induced hepatopathy based on hepatic function-associated parameters, oxidative damage-associated parameters and histological changes. The results revealed that the therapeutic effects of radon inhalation were almost equivalent to treatment with ascorbic acid at a dose of 500 mg/kg or alpha-tocopherol at a dose of 300 mg/kg. The activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver were significantly higher in mice exposed to radon than in mice treated with CCl4 alone. These findings suggest that radon inhalation has an anti-oxidative effect against CCl4-induced hepatopathy similar to the anti-oxidative effects of ascorbic acid or alpha-tocopherol due to the induction of anti-oxidative functions.

DOI： 10.1093/jrr/rrs057

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Biological response of exposure to radon progeny has long been investigated, but there are only few studies in which absorbed doses in lungs of laboratory animals were estimated. The present study is the first attempt to calculate the doses of inhaled radon progeny for mice. For reference, the doses for rats and humans were also computed with the corresponding models. Lung deposition of particles, their clearance, and energy deposition of alpha particles to sensitive tissues were systematically simulated. Absorbed doses to trachea and bronchi, bronchioles and terminal bronchioles, alveolar-interstitial regions, and whole lung were first provided as a function of monodisperse radon progeny particles with an equilibrium equivalent radon concentration of 1 Bq m(-3) (equilibrium factor, 0.4 and unattached fraction, 0.01). Based on the results, absorbed doses were then calculated for (1) a reference mine condition and (2) a condition previously used for animal experiments. It was found that the whole lung doses for mice, rats, and humans were 34.8, 20.7, and 10.7 nGy (Bq m(-3))(-1) h(-1) for the mine condition, respectively, while they were 16.9, 9.9, and 6.5 nGy (Bq m(-3))(-1) h(-1) for the animal experimental condition. In both cases, the values for mice are about 2 times higher than those for rats, and about 3 times higher than those for humans. Comparison of our data on rats and humans with those published in the literature shows an acceptable agreement, suggesting the validity of the present modeling for mice. In the future, a more sophisticated dosimetric study of inhaled radon progeny in mice would be desirable to demonstrate how anatomical, physiological, and environmental parameters can influence absorbed doses.

DOI： 10.1007/s00411-012-0431-z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

It is well known that cigarette tobaccos contain naturally occurring radioactive nuclides such as Pb-210 and Po-210. In many countries, the radioactivity of tobaccos has been measured to estimate the effective dose from smoking inhalation. The present study covered 24 cigarette brands including the top 20 of sales in Japan between April 2008 and March 2009. The activity concentrations of Pb-210 were measured by gamma-ray spectrometry, and then those of its progeny (Po-210) were evaluated assuming the radioactive equilibrium between the two nuclides. Their concentrations were in the range of 214 mBq cigarette(1) with an arithmetic mean of 83 mBq cigarette(1). The annual committed effective doses were also calculated, based on the scenario that a smoker consumes 20 cigarettes a day. The average doses from Pb-210 and Po-210 inhalations were 229 and 6827 Sv y(1), respectively.

DOI： 10.1093/rpd/ncr364

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

We assessed whether radon inhalation inhibited carrageenan-induced inflammation in mice. Carrageenan (1% v/v) was injected subcutaneously into paws of mice that had or had not inhaled approximately 2,000 Bq/m(3) of radon for 24 h. Radon inhalation significantly increased superoxide dismutase (SOD) and catalase activities and significantly decreased lipid peroxide levels in mouse paws, indicating that radon inhalation activates antioxidative functions. Carrageenan administration induced paw edema and significantly increased tumor necrosis factor-alpha (TNF-alpha) and nitric oxide in serum. However, radon inhalation significantly reduced carrageenan-induced paw edema. Serum TNF-alpha levels were lower in the radon-treated mice than in sham-treated mice. In addition, SOD and catalase activities in paws were significantly higher in the radon-treated mice than in the sham-treated mice. These findings indicated that radon inhalation had anti-inflammatory effects and inhibited carrageenan-induced inflammatory paw edema.

DOI： 10.1007/s10753-011-9364-y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The energy spectra of X-rays produced by an LiTaO3 single crystal have been measured at pressures of 5-50 Pa. The energy spectra showed that the amount of X-rays increased exponentially and the endpoint energy of the spectra increased linearly with the decrease of pressure at pressures of 10-25 Pa. A maximum endpoint energy of about 22 key was obtained using an LiTaO3 single crystal with 0.5 mm thickness at the pressure of 10 Pa. The maximum energy produced by the present experimental setup was estimated assuming that the LiTaO3 single crystal forms a parallel-plate capacitor. The estimated energy reasonably agreed with the energy obtained. The pressure dependence of the endpoint energy was discussed in relation to the breakdown potential at low pressures. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2011.12.028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IJRR-IRANIAN JOURNAL RADIATION RES  

Background: The aim of this study was to analyze the effects of thoron and thermal treatment for aging-related diseases in humans. Materials and Methods: All subjects inhaled thoron with a high concentration (about 4900 Bq/m(3)) for 2 weeks. Blood pressures were measured and blood samples were collected after each treatment 1, 2 and 3 weeks after the first treatment. Results: The alpha-atrial natriuretic peptide level of the rheumatoid arthritis group was increased and the blood pressure was significantly decreased. Superoxide dismutase activity of rheumatoid arthritis group was significantly increased by treatment. In addition, thoron and thermal treatment significantly enhanced the concanavalin A-induced mitogen response and increased the level of CD4-positive cells; it decreased the level of CD8-positive cells. The results suggest that thoron and thermal treatment activates antioxidative function. Furthermore, these findings suggest that thoron and thermal treatment prevents diabetic ketoacidosis and contributes to the prevention of aging-related diseases. Conclusion: Thoron and thermal therapy may be part of the mechanism for the alleviation of diabetes mellitus and rheumatoid arthritis. Iran. J. Radiat. Res., 2012; 9(4): 221-229

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

We examined the inhibitory effects of low-dose X-irradiation on mouse brain tissue with cold-induced injury by comparing tissue samples from three groups of mice: control, sham-irradiated cold-exposed, and X-ray-irradiated (0.5 Gy) cold-exposed mice. The water content in brain increased significantly in the sham-irradiated group following the cold-induced injury relative to the control group. However, water content in brain tissue from the X-ray-irradiated group was significantly lower than that from the sham-irradiated group. Levels of antioxidants, such as superoxide dismutase and glutathione, in brain tissue from the X-ray-irradiated group were higher than those from the sham-irradiated group. Moreover, the cold injury-induced cell death, particularly apoptosis, while low-dose irradiation inhibited cell death, especially among glial cells, but not numeral cells. These findings suggest that prior low-dose X-irradiation activated antioxidant function and inhibited cold-induced brain injury.

DOI： 10.1007/s10753-011-9293-9

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Since the 2011 nuclear accident in Fukushima, the effects of low-dose irradiation, especially internal exposure, are at the forefront of everyone's attention. However, low-dose radiation induced various stimulating effects such as activation of antioxidative and immune functions. In this study, we attempted to evaluate the quantitative effects of the activation of antioxidative activities in kidney induced by radon inhalation on carbon tetrachloride (CCl4)-induced renal damage. Mice were subjected to intraperitoneal (i.p.) injection of CCl4 after inhaling approximately 1000 or 2000 Bq/m(3) radon for 24 h, or immediately after i.p. injection of alpha-tocopherol (100, 300, or 500 mg/kg bodyweight). In case of renal function, radon inhalation at a concentration of 2000 Bq/m(3) has the inhibitory effects similar to alpha-tocopherol treatment at a dose of 300-500 mg/kg bodyweight. The activities of superoxide dismutase and catalase in kidneys were significantly higher in mice exposed to radon as compared to mice treated with CCl4 alone. These findings suggest that radon inhalation has an antioxidative effect against CCl4-induced renal damage similar to the antioxidative effects of alpha-tocopherol due to induction of antioxidative functions.

DOI： 10.3109/0886022X.2012.717496

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Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.61.1

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Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.61.231

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORPORATION  

We previously reported that radon inhalation activates antioxidative functions in the liver and inhibits carbon tetrachloride-induced hepatopathy in mice. In addition, it has been reported that reactive oxygen species contribute to alcohol-induced hepatopathy. In this study, we examined the inhibitory effects of radon inhalation on acute alcohol- induced hepatopathy in mice. C57BL/6J mice were subjected to intraperitoneal injection of 50% alcohol (5 g/kg bodyweight) after inhaling approximately 4000 Bq/m(3) radon for 24 h. Alcohol administration significantly increased the activities of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) in serum, and the levels of triglyceride and lipid peroxide in the liver, suggesting acute alcohol- induced hepatopathy. Radon inhalation activated antioxidative functions in the liver. Furthermore, pretreatment with radon inhibited the depression of hepatic functions and antioxidative functions. These findings suggested that radon inhalation activated antioxidative functions in the liver and inhibited acute alcohol- induced hepatopathy in mice.

DOI： 10.1155/2012/382801

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI LTD  

The enhanced release of reactive oxygen species from activated neutrophils plays important role in the pathogenesis of inflammatory bowel disease. We previously reported that radon inhalation activates antioxidative functions in various organs of mice. In this study, we examined the protective effects of radon inhalation on dextran sulfate sodium- (DSS) induced colitis in mice which were subjected to DSS for 7 days. Mice were continuously treated with air only (sham) or radon at a concentration of 2000 Bq/m(3) from a day before DSS administration to the end of colitis induction. In the results, radon inhalation suppressed the elevation of the disease activity index score and histological damage score induced by DSS. Based on the changes in tumor necrosis factor-alpha in plasma and myeloperoxidase activity in the colon, it was shown that radon inhalation suppressed DSS-induced colonic inflammation. Moreover, radon inhalation suppressed lipid peroxidation of the colon induced by DSS. The antioxidant level (superoxide dismutase and total glutathione) in the colon after DSS administration was significantly higher in mice treated with radon than with the sham. These results suggested that radon inhalation suppressed DSS-induced colitis through the enhancement of antioxidative functions in the colon.

DOI： 10.1155/2012/239617

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

We assessed whether radon inhalation provided protection from carbon tetrachloride (CCl4)-induced hepatic and renal damage in mice. Mice were subjected to intraperitoneal injection of CCl4 after inhaling approximately 18 kBq/m(3) radon for 6 h. Radon inhalation significantly increased total glutathione (t-GSH) content and glutathione peroxidase (GPx) activity in the liver and kidney. Injection of CCl4 was associated with significantly higher levels of glutamic oxaloacetic transaminase (GOT) and alkaline phosphatase (ALP) activity and creatinine level in serum, and pretreatment with radon significantly decreased the GOT and ALP activity and creatinine level associated with CCl4 injection, suggesting that radon inhalation alleviates CCl4-induced hepatic and renal damage. The t-GSH contents and GPx activity in the liver and kidney of animals pretreated with radon were significantly higher than those of the CCl4-only group. These findings suggested that radon inhalation activated antioxidative functions and inhibited CCl4-induced hepatic and renal damage in mice.

DOI： 10.1007/s10753-010-9263-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN RADIATION RESEARCH SOC  

We 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(3) for 0.5, 1, 2, 4, or 8 days. When mice were exposed to radon at 2000 day.Bq/m(3), 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.

DOI： 10.1269/jrr.10072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

A radon test facility for small animals was developed in order to increase the statistical validity of differences of the biological response in various radon environments. This paper illustrates the performances of that facility, the first large-scale facility of its kind in Japan. The facility has a capability to conduct approximately 150 mouse-scale tests at the same time. The apparatus for exposing small animals to radon has six animal chamber groups with five independent cages each. Different radon concentrations in each animal chamber group are available. Because the first target of this study is to examine the in vivo behaviour of radon and its effects, the major functions to control radon and to eliminate thoron were examined experimentally. Additionally, radon progeny concentrations and their particle size distributions in the cages were also examined experimentally to be considered in future projects.

DOI： 10.1093/rpd/ncr100

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

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(4)) administration. Results showed that radon inhalation alleviates CCl(4)-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.

DOI： 10.1093/rpd/ncr189

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OKAYAMA UNIV MED SCHOOL  

No research has been conducted on the radiation influence of tobacco on the alimentary system, although there have been some previous works on the respiratory system. In this study, the radioactive concentrations of Pb-210 and K-40 in a cigarette sample were first measured. The transfer factors of the nuclides from tobacco into smoke and solution (saliva and/or alcohol) were then examined. Moreover, the radiation doses from smoke inhalation were also evaluated. The radioactive concentrations of Pb-210 and K-40 in the cigarette tobacco were 0.01 and 0.3 Bq/cigarette. Since this Pb-210 activity and the Po-210 activity previously reported for the same sample were comparable, it can be concluded that there was a radioactive equilibrium between the 2 nuclides. The observed transfer factor of Pb-210 (12%) into smoke was almost the same as that of K-40 (15%), whereas the reported value for Po-210 (60%) was significantly higher. The radiation doses due to inhalation of cigarette smoke varied from organ to organ, depending on the organotropic properties of the nuclide. For example, the kidneys, respiratory tract, and spleen showed relatively high doses from Pb-210 and Po-210. The leaching rates indicated an inconsistent tendency related to solution types. This result could suggest that alcohol drinking, which is common in smokers, does not especially enhance the leaching characteristics.

DOI： 10.18926/AMO/45267

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Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Radiation Safety Management  

DOI： 10.12950/rsm.10.1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The performance of imaging plates (IPs) has not been studied at temperatures lower than 0 degrees C. In the present study, an IP was irradiated with gamma rays emitted from the mineral monazite at temperatures between -80 and 30 degrees C 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 0 degrees C, was not observed at -30 and 80 degrees C. Furthermore, the fading-corrected PSL value of the IP irradiated at 80 degrees C was lower than at other temperatures (30.5 and -30 degrees C). This can be explained by thermostimulated luminescence (TSL). Since the only intensive TSL peak in the temperature range from -80 to 30 degrees C is present at about -43 degrees C, 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. This finding suggests that the apparent sensitivity of the IP is lower at -80 degrees C although it is similar to sensitivities between -30 and 30 degrees C. This low sensitivity should be corrected to perform quantitative measurements. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apradiso.2010.03.020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

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(-3))(-1) day(-1) for all the species. Although the dose rates are not so high, it may be better to pay attention to the dose to the red bone marrow from the perspective of radiation protection. For more accurate dose assessment, it is necessary to update tissue/blood partition coefficients of radon that strongly govern the result of the PBPK modeling.

DOI： 10.1080/18811248.2010.9711649

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apradiso.2009.11.070

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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 ((238)U and (226)Ra) and radon emanation fraction of the minerals were then studied by gamma-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 (226)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. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apradiso.2009.12.036

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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 inn 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. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.radmeas.2010.01.010

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Publishing type：Research paper (scientific journal)   Publisher：Japan Health Physics Society  

DOI： 10.5453/jhps.45.65

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Language：Japanese   Publisher：Japanese Society of Clinical Veterinary Medicine  

The purpose of this study was to estimate the effective dose of radiation to which veterinary staff were exposed during general radiographic procedures. The Ordinance for Enforcement of Veterinary Practice Act has published dose limits of occupational exposure in accordance with the International Commission on Radiological Protection. According to the recommendation, exposure of any radiation worker must be maintained beneath a certain dose limit, that is, the dose must not exceed 20 mSv per year for 5 consecutive years. But there is danger that single dosimetry under a lead apron might lead to underestimation of the dose that a radiation worker actually received. Calculation by single dosimetry is done as if the whole body was radiated uniformly, although protective shielding such as a lead apron covers the body widely. The Act requires double dosimetry to estimate the effective dose of radiation more exactly, and requires that a radiation worker should wear an additional dosimeter at the location at which he or she receives the highest deep-dose equivalent. Experimentally, using a double dosimitry model, we tested and calculated the effective dose for veterinary staff: it was 2.4 micro Sv per one radiograph. By extrapolation, it is estimated that the limit of 20 mSv per year will be exceeded when, for example, one veterinary nurse is engaged in holding an animal down on the stand to take one radiograph, more than 160 times per week, excluding exposure of the hands.

DOI： 10.11252/dobutsurinshoigaku.19.113

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL CLINICAL BIOCHEMISTRY & NUTRITION  

We previously reported that low-dose X-irradiation alleviates ischemia-reperfusion injury such as mouse paw edema. In this study, we examined active changes in the biological function of mouse liver grafts in cold storage after low-dose X-irradiation. Mouse livers were sham-irradiated or were irradiated with 0.25, 0.5, 1.0, or 5.0 Gy of X-ray and stored for 4, 8, 24, or 48 h in preservation or saline solution. The results show that storage for 24 h in saline solution after 0.5 Gy irradiation significantly increased the activity of superoxide dismutase (SOD) and catalase. Following storage for 4, 8, or 48 h in preservation solution, lipid peroxide levels of the 0.5 Gy irradiated group were significantly lower than those of the sham irradiated group. Following storage for 24 h in preservation solution, the activity of SOD and catalase of the 1.0 Gy irradiated group were significantly higher than those of the sham irradiated group. Hepatocytes stored in saline solution were vacuolated. However, no vacuole formation was observed in hepatocytes stored in preservation solution. These findings suggest that low-dose irradiation significantly activates antioxidative functions of liver grafts. Moreover, the dose at which enhancement of antioxidative function occurs in livers stored in preservation solution, which contains glutathione, is significantly higher than that in saline solution.

DOI： 10.3164/jcbn.09-06

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOURNAL CLINICAL BIOCHEMISTRY & NUTRITION  

To elucidate the radiosensitivity of an acatalasemic mouse, we examined the time and dose-dependency in the survival rates, the lymphocytes and the intestinal epithelial cells, and the antioxidant function after 3.0 to 12.0 Gy whole body irradiation. Results showed that no significant differences between acatalasemic mice and normal mice were observed in the survival rates and the histological changes in spleens and small intestine after each irradiation. The catalase activities in livers and spleens of acatalasemic mice were significantly lower than those of normal mice and the glutathione peroxidase activity in livers of acatalasemic mice was significantly higher than that of normal mice. At 10 days after 6.0 Gy irradiation, the catalase activities in livers of acatalasemic and normal mice and that in spleens of normal mice significantly decreased compared with no-irradiation control, and there were no differences between those catalase activities. The total glutathione content in acatalasemic mice was significantly higher than that in normal mice at 10 days after 6.0 Gy irradiation. These findings suggested that the radiosensitivity of acatalasemic mice in terms of whole body irradiation doesn't significantly differ from that of normal mice, probably due to compensated sufficient contents of glutathione peroxidase and total glutathione in acatalasemic mice.

DOI： 10.3164/jcbn.2008042

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Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.57.241

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We 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 I hr after reperfusion from ischemia for I 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 I 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.

DOI： 10.1269/jrr.07060

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Language：English   Publishing type：Research paper (scientific journal)  

Exposure to water in hot springs containing thoron is thought to exercise beneficial effects on hypertension and diabetes mellitus. To put to a test this hypothesis we examined the time dependent changes in the levels of lipid peroxide, vasoactive- and diabetes associated substances in human blood in order to throw further light on the possible beneficial influence of thoron and thermal therapy on the mechanism of hypertension and diabetes mellitus. Every 2 days, nasal inhalation of vapor containing thoron was performed for 40 min. Blood samples were collected after each treatment at 1,2, and 3 weeks after the first treatment. Results show that the treatment decreased the lipid peroxide levels. The finding suggests that the treatment contributes to the prevention of peroxidation reaction related to hypertension and diabetes mellitus. Moreover, the changes in vasoactive-associated substances indicate an increase in tissue perfusion, suggesting that the treatment plays a role in alleviating hypertension. The treatment decreased the total ketone body levels and the finding suggests that the treatment contributes to the prevention of diabetes mellitus related to the insulin deficiency.

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Language：English   Publishing type：Research paper (scientific journal)  

We have previously determined by using immune-assay or bio-assay methods that low-dose irradiation enhances immune and anti-oxidation functions. In this study, we examined histological changes of lymphatic follicles at 4, 24, or 48 hrs after sham, 0.25, 0.5, or 15 Gy irradiation in the spleens of BALB/c mice, which are sensitive to radiation compared with other strains, and C57BL/6J mice, which are resistant to radiation, using hematoxylin-eosin staining for lymphatic follicles or methylgreen pyronin staining for plasma cells. Results show that the lymphatic follicles in the spleens of the two mouse strains decreased at 24 or 48 hrs after 15 Gy irradiation. The number of plasma cells in the spleens of sham irradiated BALB/c mice was greater than that of sham irradiated C57BL/6J mice. At 4 hrs after 0.25 Gy irradiation, plasma cells increased in the spleens of the two mouse strains. These findings suggest, by histology, that low-dose irradiation activates the plasma cells and enhances the immune function. Although those two mouse strains have different sensitivities to radiation, the above changes were similar in both time course and degree of response. Therefore, the phenomena observed may be common in mice.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN RADIATION RESEARCH SOC  

To 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.

DOI： 10.1269/jrr.46.21

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Language：English   Publishing type：Research paper (scientific journal)  

The catalase activities in the blood and organs of the acatalasemic (C3H/AnLCsb-Csb) mouse of the C3H strain are lower than those of the normal (C3H/AnLCsa-Csa) mouse. We examined the effects of post low-dose (0.5 Gy) X-ray irradiation which reduced the oxidative damage under carbon tetrachloride-induced hepatopathy in acatalasemic or normal mice. As a result, the 0.5 Gy irradiation after carbon tetrachloride administration decreased the glutamic oxaloacetic and glutamic pyruvic transaminase activity in the acatalasemic mouse blood to a level similar to that of the acatalasemic mouse blood not treated with carbon tetrachloride
this is in contrast to a high-dose (15 Gy) irradiation. In the same manner, pathological disorder was improved by 0.5 Gy irradiation. The fat degeneration in normal mice was quickly reduced, in contrast to acatalasemic mice. These findings suggest that low-dose irradiation after carbon tetrachloride administration accelerates the rate of recovery and that catalase plays an important role in the recovery from hepatopathy induced by carbon tetrachloride, in contrast to high-dose irradiation.

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Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.54.375

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN RADIATION RESEARCH SOC  

The catalase activities in blood and organs of the acatalasemic (C3H/AnLCs(b)Cs(b)) mouse of C3H strain are lower than those of the normal (C3H/AnLCs(a)Cs(a)) 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.

DOI： 10.1269/jrr.45.89

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Language：Japanese   Publisher：公益社団法人 日本アイソトープ協会  

<p>トロン（Rn）吸入とアスコルビン酸（AA）投与による急性アルコール性マウス肝障害の抑制効果について検討した。その結果，肝障害の程度はアルコール投与後6時間の方が24時間より，肝臓への中性脂肪の蓄積は投与後24時間の方が6時間より，各々大きいことがわかった。また，アルコール投与後24時間のRn吸入とAA投与の併用は，肝障害と肝臓への中性脂肪の蓄積の回復を早めることもわかった。</p>

DOI： 10.50955/happyokai.1.0_85

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Language：Japanese   Publisher：公益社団法人 日本アイソトープ協会  

<p>ウイルス感染症などで注目されている血中サイトカインに着目し，ラドン吸入による変化特性についてマウスを用い検討した。その結果，IL-6やTNF-α等の炎症性サイトカイン，IL-4やIL-10等の抗炎症性サイトカインが，各々興味深い変化をすることがわかった。また，吸入時間は４週間の方が２週間よりも顕著であることから，その変化特性に時間依存性があることもわかった。</p>

DOI： 10.50955/happyokai.1.0_87

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Language：Japanese   Publisher：公益社団法人 日本アイソトープ協会  

<p>本研究では、ラドン吸入とイオウ関連代謝物との関連を検討することを目的とし、ラドンを吸入させたマウスの臓器を用いてメタボローム解析を行った。しかしながら、代謝物の変化とラドン総曝露量に相関はなかった。そこで、機械学習によるデータ解析を行い、メタボローム解析結果を可視化した。ここでは、多数の代謝物の変化を総合的に評価することで明らかになったラドン曝露量とイオウ関連代謝物との関連について報告する。</p>

DOI： 10.50955/happyokai.1.0_131

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Language：Japanese   Publisher：放射線生物研究会  

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Event date： 2021.7.7 - 2021.7.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.5.19 - 2021.5.20

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Event date： 2018.11.17

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Event date： 2018.11.17

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