Okayama University Medical SchoolActa Medica Okayama0386-300X7742023Association between Radon Hot Spring Bathing and Health Conditions: A Cross-Sectional Study in Misasa, Japan387394ENTakahiroKataokaDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesHiroshiHabuDepartment of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesAyumiTanakaDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesShotaNaoeDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesKaitoMurakamiDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesYukiFujimotoDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesRyoheiYukimineDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesSoshiTakaoDepartment of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesFumihiroMitsunobuDepartment of Longevity and Social Medicine (Geriatrics), Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesTakashiYorifujiDepartment of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical SciencesKiyonoriYamaokaDepartment of Radiological Technology, Okayama University Graduate School of Health SciencesOriginal Article10.18926/AMO/65749No epidemiological studies have examined the health effects of daily bathing in radon hot springs. In this cross-sectional study, we investigated the associations between radon hot spring bathing and health conditions. The target population was 5,250 adults ≥ 20 years old in the town of Misasa, Japan. We collected information about the participants’ bathing habits and alleviation of a variety of disease symptoms, and their self-rated health (SRH). Unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CI) were calculated. In both the adjusted and unadjusted models of hypertension, significant associations between the > 1×/week hot spring bathing and the alleviation of hypertension symptoms were observed compared to the group whose hot spring bathing was <1×/week: adjusted model, OR 5.40 (95%CI: 1.98-14.74); unadjusted model, 3.67 (1.50-8.99) and for gastroenteritis: adjusted model, 9.18 (1.15-72.96); unadjusted model, 7.62 (1.59-36.49). Compared to the no-bathing group, higher SRH was significantly associated with both bathing < 1×/week: unadjusted model, 2.27 (1.53-3.37) and > 1×/week: adjusted model, 1.91 (1.15-3.19). These findings suggest that bathing in radon hot springs is associated with higher SRH and the alleviation of hypertension and gastroenteritis.No potential conflict of interest relevant to this article was reported.Oxford University Press Acta Medica Okayama0449-30606442023Effects of low-dose/high-dose-rate X-irradiation on oxidative stress in organs following forced swim test and its combined effects on alcohol-induced liver damage in mice635643ENShotaNaoeGraduate School of Health Sciences, Okayama UniversityYukiFujimotoGraduate School of Health Sciences, Okayama UniversityKaitoMurakamiGraduate School of Health Sciences, Okayama UniversityRyoheiYukimineGraduate School of Health Sciences, Okayama UniversityAyumiTanakaGraduate School of Health Sciences, Okayama UniversityKiyonoriYamaokaFaculty of Health Sciences, Okayama UniversityTakahiroKataokaFaculty of Health Sciences, Okayama UniversityThe liver's susceptibility to oxidative stress after a combination of forced swim test (FST) and low-dose-rate gamma-irradiation has been observed. Therefore, this study aims to clarify the effects of low-dose (0.1 and 0.5 Gy)/high-dose-rate (1.2 Gy/min) irradiation on combined oxidative stressors-liver damage associated with FST and alcohol administration. In addition, the effects of similar irradiation on FST-induced immobility, which induces psychomotor retardation, and antioxidative effects on the brain, lungs, liver and kidneys were investigated, and the results were compared with those of a similar previous study that utilized low-dose-rate irradiation. Low-dose/high-dose-rate (especially 0.5 Gy) irradiation temporarily worsened liver antioxidant function and hepatic function with FST- and alcohol administration-related oxidative damage; however, the damages improved soon after. In addition, the increase in total glutathione content in the liver contributed to the early improvement of hepatic functions. However, pre-irradiation did not suppress immobility during the FST. The results also suggested that the effects of low-dose/high-dose-rate irradiation on the antioxidant functions of each organ after the FST were different from those of low-dose/low-dose-rate irradiation. Overall, this study provides further insights into the effects of low-dose irradiation on exposure to a combination of different oxidative stressors. It will also contribute to the elucidation of dose rate effects on oxidative stress in the low-dose irradiation range.No potential conflict of interest relevant to this article was reported.MDPIActa Medica Okayama1660-460119172022Immunomodulatory Effects of Radon Inhalation on Lipopolysaccharide-Induced Inflammation in Mice10632ENTakahiroKataokaFaculty of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityKaitoMurakamiGraduate School of Health Sciences, Okayama UniversityYukiFujimotoGraduate School of Health Sciences, Okayama UniversityRyoheiYukimineGraduate School of Health Sciences, Okayama UniversityAyumiTanakaGraduate School of Health Sciences, Okayama UniversityKiyonoriYamaokaFaculty of Health Sciences, Okayama UniversityTypical indications for radon therapy include autoimmune diseases such as rheumatoid arthritis (RA). We had previously reported that radon inhalation inhibits Th17 immune responses in RA mice by activating Th1 and Th2 immune responses. However, there are no reports on how radon inhalation affects the activated Th1 and Th17 immune responses, and these findings may be useful for identifying new indications for radon therapy. Therefore, in this study, we investigated the effect of radon inhalation on the lipopolysaccharide (LPS)-induced inflammatory response, focusing on the expression of related cytokines and antioxidant function. Male BALB/c mice were exposed to 2000 Bq/m(3) radon for one day. Immediately after radon inhalation, LPS was administered intraperitoneally at 1.0 mg/kg body weight for 4 h. LPS administration increased the levels of Th1- and Th17-prone cytokines, such as interleukin-2, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor, compared to no treatment control (sham). However, these effects were suppressed by radon inhalation. IL-10 levels were significantly increased by LPS administration, with or without radon inhalation, compared to sham. However, radon inhalation did not inhibit oxidative stress induced by LPS administration. These findings suggest that radon inhalation has immunomodulatory but not antioxidative functions in LPS-induced injury.No potential conflict of interest relevant to this article was reported.Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology. Acta Medica Okayama0449-30602022Potential inhibitory effects of low-dose thoron inhalation and ascorbic acid administration on alcohol-induced hepatopathy in miceENTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityTsuyoshiIshidaGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityNorieKanzakiNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyAkihiroSakodaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyHiroshiTanakaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyFumihiroMitsunobuGraduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityAlthough thoron inhalation exerts antioxidative effects in several organs, there are no reports on whether it inhibits oxidative stress-induced damage. In this study, we examined the combined effects of thoron inhalation and ascorbic acid (AA) administration on alcohol-induced liver damage. Mice were subjected to thoron inhalation at 500 or 2000 Bq/m(3) and were administered 50% ethanol (alcohol) and 300 mg/kg AA. Results showed that although alcohol administration increased the levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) in the serum, the combination of thoron inhalation (500 Bq/m(3)) and AA administration 24 h after alcohol administration effectively inhibited alcohol-induced liver damage. The combination of thoron inhalation (500 Bq/m(3)) and AA administration 24 h after alcohol administration increased catalase (CAT) activity. Alcohol administration significantly decreased glutathione (GSH) levels in the liver. The GSH content in the liver after 2000 Bq/m(3) thoron inhalation was lower than that after 500 Bq/m(3) thoron inhalation. These findings suggest that the combination of thoron inhalation at 500 Bq/m(3) and AA administration has positive effects on the recovery from alcohol-induced liver damage. The results also suggested that thoron inhalation at 500 Bq/m(3) was more effective than that at 2000 Bq/m(3), possibly because of the decrease in GSH content in the liver. In conclusion, the combination of thoron inhalation at 500 Bq/m(3) and AA administration promoted an early recovery from alcohol-induced liver damage.No potential conflict of interest relevant to this article was reported.The Society for Free Radical Research JapanActa Medica Okayama0912-00097022022Confirmation of efficacy, elucidation of mechanism, and new search for indications of radon therapy8792ENKiyonoriYamaokaHealth Sciences, Institute of Academic and Research, Okayama UniversityTakahiroKataokaHealth Sciences, Institute of Academic and Research, Okayama UniversityIndications of radon therapy include various diseases related to respiratory, painful, digestive, chronic degenerative, senile, etc. derived from reactive oxygen species, but most are based on empirical prescriptions. For this reason, we have evaluated the relation between the biological response caused by radon and the tissue/organ absorbed dose more quantitatively, and have promoted the elucidation of mechanisms related to the indication and searching newly. As a result, as a mechanism, a series of moderate physiological stimulative effects accompanying a small amount of oxidative stress by radon inhalation are being elucidated. That is, hyperfunction of anti-oxidation/immune regulation/damage repair, promotion of anti-inflammation/circulating metabolism/hormone secretion, induction of apoptosis/heat shock protein, etc. Also, new indications include inflammatory/neuropathic pain, hepatic/renal injury, colitis, type 1 diabetes, complication kidney injury, hyperuricemia, transient cerebral ischemia, and inflammatory edema. Furthermore, we examined the combined antioxidant effect of radon inhalation and antioxidants or therapeutic agents. As a result, it was clear that any combination treatment could enhance the suppression effect of disease. It can be expected that radon therapy can be used effectively by applying it in addition to usual treatment, since reduction in its dosage can also be expected by concomitant use for drugs with strong side effects.No potential conflict of interest relevant to this article was reported.The Society for Free Radical Research JapanActa Medica Okayama0912-00097022022Mechanisms of action of radon therapy on cytokine levels in normal mice and rheumatoid arthritis mouse model154159ENTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityKaitoMurakamiGraduate School of Health Sciences, Okayama UniversityRyoheiYukimineGraduate School of Health Sciences, Okayama UniversityYukiFujimotoGraduate School of Health Sciences, Okayama UniversityNorieKanzakiNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyAkihiroSakodaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyFumihiroMitsunobuGraduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityThe typical indication of radon therapy is rheumatoid arthritis. Although there are several reports that radon therapy has regulation effects on Th17 cells, there has been no study reporting that radon inhalation affects the immune balance among Th1, Th2, and Th17. The purpose of this study is to examine the cytokine changes after radon inhalation. BALB/c mice inhaled radon at 2,000 Bq/m3 for 2 or 4 weeks. SKG/Jcl mice inhaled radon at 2,000 Bq/m3 for 4 weeks after zymosan administration. The results showed that radon inhalation for 4 weeks activated the immune response of Th1, Th2, and Th17. Moreover, the balance among them was not lost by radon inhalation. Radon inhalation for 4 weeks decreased superoxide dismutase activity and increased catalase activity in spleen. These findings suggest that an imbalance of oxidative stress may contribute to activate the immune response. Although zymosan administration activated Th17 immune response and decreased Th1 and Th2 immune response in SKG/Jcl mice, most cytokines related to Th1, Th2, and Th17 approached the normal level by radon inhalation. These findings suggested that radon inhalation has a different action between SKG/Jcl mice and normal BABL/c mice. This may indicate that radon inhalation has an immunomodulation function.No potential conflict of interest relevant to this article was reported.Oxford University PressActa Medica Okayama0449-30606252021Radon inhalation decreases DNA damage induced by oxidative stress in mouse organs via the activation of antioxidative functions861867ENTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityHinaShutoGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityJunkiYanoGraduate School of Health Sciences, Okayama UniversityNorieKanzakiNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyAkihiroSakodaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyHiroshiTanakaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyKatsumiHanamotoGraduate School of Health Sciences, Okayama UniversityFumihiroMitsunobuGraduate School ofMedicine Dentistry and Pharmaceutical Sciences, Okayama UniversityHiroakiTeratoAdvanced Science Research Center Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityRadon 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/m(3) (for one, three, or 10 days). The 8-hydroxy-2 '-deoxyguanosine (8-OHdG) levels decreased in the brains of mice that inhaled 20 kBq/m(3) radon for three days and in the kidneys of mice that inhaled 2 or 20 kBq/m(3) radon for one, three or 10 days. The 8-OHdG levels in the small intestine decreased by approximately 20-40% (2 kBq/m(3) for three days or 20 kBq/m(3) 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.No potential conflict of interest relevant to this article was reported.Oxford Univ PressActa Medica Okayama0449-30606232021Evaluation of the redox state in mouse organs following radon inhalation390400ENTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityNorieKanzakiNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyAkihiroSakodaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyHinaShutoGraduate School of Health Sciences, Okayama UniversityJunkiYanoGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityHiroshiTanakaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyKatsumiHanamotoGraduate School of Health Sciences, Okayama UniversityHiroakiTeratoAdvanced Science Research Center, Okayama UniversityFumihiroMitsunobuGraduate School ofMedicine Dentistry and Pharmaceutical Sciences, Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityRadon 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/m(3) 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.No potential conflict of interest relevant to this article was reported.OXFORD UNIV PRESSActa Medica Okayama0449-30606142020X-Irradiation at 0.5 Gy after the forced swim test reduces forced swimming-induced immobility in mice517523ENTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityHinaShutoGraduate School of Health Sciences, Okayama UniversityJunkiYanoGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityTsuyoshiIshidaGraduate School of Health Sciences, Okayama UniversityTetsuyaNakadaGraduate School of Health Sciences, Okayama UniversityKeikoYamatoLaboratory of Neurology and Neurosurgery, National Cerebral and Cardiovascular CenterKatsumiHanamotoGraduate School of Health Sciences, Okayama UniversityTakaharuNomuraCentral Research Institute of Electric Power IndustryKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityThe 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 4h 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.No potential conflict of interest relevant to this article was reported.SpringerActa Medica Okayama0301634X5932020Comparison of antioxidative effects between radon and thoron inhalation in mouse organsENYusukeKobashiGraduate School of Health Sciences, Okayama UniversityTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityNorieKanzakiGraduate School of Health Sciences, Okayama UniversityTsuyoshiIshidaGraduate School of Health Sciences, Okayama UniversityAkihiroSakodaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyHiroshiTanakaNingyo-toge Environmental Engineering Center, Japan Atomic Energy AgencyYuuIshimoriPrototype Fast Breeder Reactor Monju, Japan Atomic Energy AgencyFumihiroMitsunobuGraduate School of Medicine Dentistry and Pharmaceutical Sciences, Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityRadon 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.No potential conflict of interest relevant to this article was reported.Acta Medica Okayama0962-935120122012Inhibitory Effects of Pretreatment with Radon on Acute Alcohol-Induced Hepatopathy in MiceENTeruakiToyotaTakahiroKataokaYuichiNishiyamaTakehitoTaguchiKiyonoriYamaokaWe 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.No potential conflict of interest relevant to this article was reported.Japan Radiation Research Society and Japanese Society for Therapeutic Radiology and OncologyActa Medica Okayama0449-30605362012Comparative study on the inhibitory effects of antioxidant vitamins and radon on carbon tetrachloride-induced hepatopathy830839ENTakahiroKataokaYuichiNishiyamaKeikoYamatoJunichiTeraokaYujiMoriiAkihiroSakodaYuuIshimoriTakehitoTaguchiKiyonoriYamaokaWe have previously reported that radon inhalation activates anti-oxidative functions and inhibits carbon tetrachloride (CCl(4))-induced hepatopathy. It has also been reported that antioxidant vitamins can inhibit CCl(4)-induced hepatopathy. In the current study, we examined the comparative efficacy of treatment with radon, ascorbic acid and α-tocopherol on CCl(4)-induced hepatopathy. Mice were subjected to intraperitoneal injection of CCl(4) 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 α-tocopherol (100, 300, or 500 mg/kg bodyweight). We estimated the inhibitory effects on CCl(4)-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 α-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 CCl(4) alone. These findings suggest that radon inhalation has an anti-oxidative effect against CCl(4)-induced hepatopathy similar to the anti-oxidative effects of ascorbic acid or α-tocopherol due to the induction of anti-oxidative functions.No potential conflict of interest relevant to this article was reported.Informa HealthcareActa Medica Okayama1525-60493492012Comparative Study on the Inhibitory Effects of α-Tocopherol and Radon on Carbon Tetrachloride-Induced Renal Damage11811187ENTakahiroKataokaKeikoYamatoYuichiNishiyamaYujiMoriiReoEtaniYujiTakataKatsumiHanamotoAtsuishiKawabeAkihiroSakodaYuuIshimoriTakehitoTaguchiKiyonoriYamaokaSince 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 (CCl<sub>4</sub>)-induced renal damage. Mice were subjected to intraperitoneal (i.p.) injection of CCl<sub>4</sub> after inhaling approximately 1000 or 2000 Bq/m<sup>3</sup> radon for 24 h, or immediately after i.p. injection of α-tocopherol (100, 300, or 500 mg/kg bodyweight). In case of renal function, radon inhalation at a concentration of 2000 Bq/m<sup>3</sup> has the inhibitory effects similar to α-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 CCl<sub>4</sub> alone. These findings suggest that radon inhalation has an antioxidative effect against CCl<sub>4</sub>-induced renal damage similar to the antioxidative effects of α-tocopherol due to induction of antioxidative functions.No potential conflict of interest relevant to this article was reported.Japan Radioisotope AssociationActa Medica Okayama0033-83036112012ラドン吸入がペットの健康改善に及ぼす効果に関する基礎的検討18ENTakahiroKataokaRikizoTokunagaAkihiroSakodaAtsushiKawabeKatsumiHanamotoKiyonoriYamaoka著者らは今までに,共同開発したラドン吸入装置を用いマウスにラドン吸入をさせた場合,諸臓器中の抗酸化機能が亢進する可能性などを明らかにしてきた。本研究では,ラドン吸入の獣医療への応用の可能性について新たに検討するため,健常なイヌ5頭(オス:2(1,9才),メス:3(1~5才))及び慢性腎不全症のネコ8頭(オス:3(2~6才),メス:5(5~7才))を対象に基礎的な検討をした。すなわち,約5500Bq/m<sup>3</sup>のラドンを1回30分で隔日に30日間(計15回)それぞれ吸入させた。その結果,イヌにおいて,中性脂肪が減少する可能性が示された。また,その効果は吸入開始20~30日後に現れることも示唆できた。他方,ネコにおいて,飲水量が改善し血清中クレアチニンが基準値内に減少する症例がみられるなど,慢性腎不全症に対し一定の効果が期待できる可能性が示唆された。No potential conflict of interest relevant to this article was reported.Japan Radioisotope AssociationActa Medica Okayama0033-83035742008ラドン吸入試作装置によるマウス諸臓器中の抗酸化機能の亢進に関する研究241251ENShinyaNakagawaTakahiroKataokaAkihiroSakodaYuuIshimoriKatsumiHanamotoKiyonoriYamaokaラドン療法の適応症には活性酸素に由来する生活習慣病が多く,その機構の更なる解明が期待されている。また,汎用性があり医学的効果が再現できるラドン吸入装置の構築は意義が大きい。このため,著者らは共同で開発したラドン吸入試作装置を用い,マウス諸臓器中の抗酸化機能の変化特性を検討した。ラドン吸入試作装置は,特殊加工したラドン線源を収納したユニットの数量,それへの送風量及び湿度などを調節することによりラドン濃度を自在に調整可能にするものである。この装置によりマウスに400Bq/m<sup>3</sup>あるいは4000Bq/m<sup>3</sup>のラドンを吸入させた。その結果,脳・肺・肝臓・腎臓において,抗酸化系酵素であるSODとカタラーゼの両活性が増加し,過酸化脂質量が減少した。この抗酸化機能の亢進により,本実験条件でのラドン吸入は活性酸素障害の抑制,すなわち,生活習慣病の予防や症状緩和に効果のある可能性が改めて示唆できた。No potential conflict of interest relevant to this article was reported.Japan Radioisotope AssociationActa Medica Okayama0033-83036152012Inhibitory Effects of Pre and Post Radon Inhalation on Carbon Tetrachloride-induced Oxidative Damage in Mouse Organs231241ENYuichiNishiyamaTakahiroKataokaJunichiTeraokaAkihiroSakodaYuuIshimoriKiyonoriYamaokaRadon inhalation activates antioxidative functions in some organs of mice. We examined the prevention effects of pre radon inhalation and the alleviation effects of post radon inhalation on carbon tetrachloride (CCl<sub>4</sub>)-induced oxidative damage in the brain, heart, lung, liver, and kidney of mice. In addition, we compared the effect of pre and post radon inhalation on oxidative damage. Mice inhaled radon at a concentration of 18000Bq/m<sup>3</sup> for 6hrs before or after CCl<sub>4</sub> administration. As a result, the total glutathione(t-GSH) contents and catalase(CAT) activities in the brain, heart, lung, liver, and kidney and superoxide dismutase(SOD) activities in the heart and lung were significantly higher in pre and post radon-inhaled mice than in mice treated with only CCl<sub>4</sub>. Pre radon inhalation inhibited and post radon inhalation reduced lipid peroxidation induced by CCl<sub>4</sub>. In addition, there were no significant differences in lipid peroxide(LPO) levels in the brain, heart, lung, liver, and kidney between pre and post radon-inhaled mice. These findings suggested that post radon inhalation has the same effects as pre radon inhalation against CCl<sub>4</sub>-induced oxidative damage in the brain, heart, lung, liver, and kidney.No potential conflict of interest relevant to this article was reported.Oxford University PressActa Medica Okayama0144-84201461-32011Studies on possibility for alleviation of lifestyle diseases by low-dose irradiation or radon inhalation360363ENTakahiroKataokaAkihiroSakodaMasaakiYoshimotoShinyaNakagawaTeruakiToyotaYuichiNishiyamaKeikoYamatoYuuIshimoriAtsushiKawabeKatsumiHanamotoTakehitoTaguchiKiyonoriYamaokaOur 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<sub>4</sub>) administration. Results showed that radon inhalation alleviates CCl<sub>4</sub>-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.No potential conflict of interest relevant to this article was reported.The Editorial Secretariat of JCBNActa Medica Okayama0912-00094522009Basic Study on Active Changes in Biological Function of Mouse Liver Graft in Cold Storage after Low-Dose X-Irradiation219226ENTakahiroKataokaMasaakiYoshimotoShinyaNakagawaYukoMizuguchiTakehitoTaguchiKiyonoriYamaokaWe 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.No potential conflict of interest relevant to this article was reported.The Editorial Secretariat of JCBNActa Medica Okayama0912-00094312008No Different Sensitivity in Terms of Whole-Body Irradiation between Normal and Acatalasemic Mice4149ENShinyaNakagawaTakahiroKataokaYukoMizuguchiMasaakiYoshimotoAkihiroSakodaTakaharuNomuraDa-HongWangAtsushiKawabeTakehitoTaguchiKiyonoriYamaokaTo 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.No potential conflict of interest relevant to this article was reported.Hindawi Publishing CorporationActa Medica Okayama20122012Activation of Biodefense System by Low-Dose Irradiation or Radon Inhalation and Its Applicable Possibility for Treatment of Diabetes and Hepatopathy1111ENTakahiroKataokaKiyonoriYamaokaAdequate oxygen stress induced by low-dose irradiation activates biodefense system, such as induction of the synthesis of superoxide dismutase (SOD) and glutathione peroxidase. We studied the possibility for alleviation of oxidative damage, such as diabetes and nonalcoholic liver disease. Results show that low-dose γ-irradiation increases SOD activity and protects against alloxan diabetes. Prior or post-low-dose X- or γ-irradiation increases antioxidative functions in livers and inhibits ferric nitrilotriacetate and carbon tetrachloride-induced (CCl<sub>4</sub>) hepatopathy. Moreover, radon inhalation also inhibits CCl<sub>4</sub>-induced hepatopathy. It is highly possible that low-dose irradiation including radon inhalation activates the biodefence systems and, therefore, contributes to preventing or reducing reactive oxygen species-related diabetes and nonalcoholic liver disease, which are thought to involve peroxidation.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604862007Inhibitory Effects of Prior Low-dose X-irradiation on Ischemia-reperfusion Injury in Mouse Paw505513ENTakahiroKataokaYukoMizuguchiMasaakiYoshimotoTakehitoTaguchiKiyonoriYamaokaWe have reported that low-dose, unlike high-dose, irradiation enhanced antioxidation function and reduced oxidative damage. On the other hand, ischemia-reperfusion injury is induced by reactive oxygen species. In this study, we examined the inhibitory effects of prior low-dose X-irradiation on ischemia-reperfusion injury in mouse paw. BALB/c mice were irradiated by sham or 0.5 Gy of X-ray. At 4 hrs after irradiation, the left hind leg was bound 10 times with a rubber ring for 0.5, 1, or 2 hrs and the paw thickness was measured. Results show that the paw swelling thickness by ischemia for 0.5 hr was lower than that for 2 hrs. At 1 hr after reperfusion from ischemia for 1 hr, superoxide dismutase activity in serum was increased in those mice which received 0.5 Gy irradiation and in the case of the ischemia for 0.5 or 1 hr, the paw swelling thicknesses were inhibited by 0.5 Gy irradiation. In addition, interstitial edema in those mice which received 0.5 Gy irradiation was less than that in the mice which underwent by sham irradiation. These findings suggest that the ischemia-reperfusion injury is inhibited by the enhancement of antioxidation function by 0.5 Gy irradiation.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604612005The Elevation of p53 Protein Level and SOD Activity in the Resident Blood of the Misasa Radon Hot Spring District2124ENKiyonoriYamaokaFumihiroMitsunobuShujiKojimaMisakoShibakuraTakahiroKataokaKatsumiHanamotoYoshiroTanizakiTo clarify the mechanism by which radon hot springs prevent cancer or not, in this study, blood was collected from residents in the Misasa hot spring district and in a control district. The level of a representative cancer-suppressive gene, p53, and the activity of a representative antioxidant enzyme, superoxide dismutase (SOD), were analyzed as indices. The level of serum p53 protein in the males in the Misasa hot spring district was found to be 2-fold higher than that in the control district, which is a significant difference. In the females in the Misasa hot spring district, SOD activity was approximately 15% higher than that in the control district, which is also statistically significant, and exceeded the reference range of SOD activity despite advanced age. These results suggested that routine exposure of the residents in the Misasa hot spring district to radon at a concentration about 3 times higher than the national mean induces trace active oxygen in vivo, potentiating products of cancer-suppressive gene and antioxidant function. As the p53 protein level was high in the residents in the Misasa hot spring district, apoptosis of cancer cells may readily occur.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30604512004Inhibitory Effects of Prior Low-dose X-ray Irradiation on Carbon Tetrachloride-induced Hepatopathy in Acatalasemic Mice8995ENKiyonoriYamaokaTakahiroKataokaTakaharuNomuraTakehitoTaguchiDa-HongWangShujiMoriKatsumiHanamotoShoheiKiraThe catalase activities in blood and organs of the acatalasemic (C3H/AnLCs<sup>b</sup>Cs<sup>b</sup>) mouse of C3H strain are lower than those of the normal (C3H/AnLCs<sup>a</sup>Cs<sup>a</sup>) mouse. We examined the effects of prior low-dose (0.5 Gy) X-ray irradiation, which reduced the oxidative damage under carbon tetrachloride-induced hepatopathy in the acatalasemic or normal mice. The acatalasemic mice showed a significantly lower catalase activity and a significantly higher glutathione peroxidase activity compared with those in the normal mice. Moreover, low-dose irradiation increased the catalase activity in the acatalasemic mouse liver to a level similar to that of the normal mouse liver. Pathological examinations and analyses of blood glutamic oxaloacetic and glutamic pyruvic transaminase activity and lipid peroxide levels showed that carbon tetrachloride induced hepatopathy was inhibited by low-dose irradiation. These findings may indicate that the free radical reaction induced by the lack of catalase and the administration of carbon tetrachloride is more properly neutralized by high glutathione peroxidase activity and low-dose irradiation in the acatalasemic mouse liver.No potential conflict of interest relevant to this article was reported.Journal of Radiation Research Editorial CommitteeActa Medica Okayama0449-30605262011Study of the Response of Superoxide Dismutase in Mouse Organs to Radon Using a New Large-scale Facility for Exposing Small Animals to Radon775781ENTakahiroKataokaAkihiroSakodaYuuIshimoriTeruakiToyotaYuichiNishiyamaHiroshiTanakaFumihiroMitsunobuKiyonoriYamaokaWe examined dose–dependent or dose rate–dependent changes of superoxide dismutase (SOD) activity using a new large-scale facility for exposing small animals to radon. Mice were exposed to radon at a concentration of 250, 500, 1000, 2000, or 4000 Bq/m<sup>3</sup> for 0.5, 1, 2, 4, or 8 days. When mice were exposed to radon at 2000 day•Bq/m<sup>3</sup>, activation of SOD activities in plasma, liver, pancreas, heart, thymus, and kidney showed dose–rate effects. Our results also suggested that continuous exposure to radon increased SOD activity, but SOD activity transiently returned to normal levels at around 2 days. Moreover, we classified the organs into four groups (1. plasma, brain, lung; 2. heart, liver, pancreas, small intestine; 3. kidney, thymus; 4. stomach) based on changes in SOD activity. Thymus had the highest responsiveness and stomach had lowest. These data provide useful baseline measurements for future studies on radon effects.No potential conflict of interest relevant to this article was reported.Springer Science+Business Media, LLCActa Medica Okayama0360-39973522012Protective Effects of Radon Inhalation on Carrageenan-Induced Inflammatory Paw Edema in Mice713722ENTakahiroKataokaJunichiTeraokaAkihiroSakodaYuichiNishiyamaKeikoYamatoMayukoMondenYuuIshimoriTakaharuNomuraTakehitoTaguchiKiyonoriYamaokaWe 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<sup>3</sup> 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-α) and nitric oxide in serum. However, radon inhalation significantly reduced carrageenan-induced paw edema. Serum TNF-α 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.No potential conflict of interest relevant to this article was reported.Springer Science+Business Media, LLCActa Medica Okayama0360-39973462011Radon Inhalation Protects Mice from Carbon-Tetrachloride-Induced Hepatic and Renal Damage559567ENTakahiroKataokaYuichiNishiyamaTeruakiToyotaMasaakiYoshimotoAkihiroSakodaYuuIshimoriYutakaAoyamaTakehitoTaguchiKiyonoriYamaokaNo potential conflict of interest relevant to this article was reported.Springer Science+Business Media, LLCActa Medica Okayama0360-39973512012Inhibitory Effects of Prior Low-dose X-irradiation on Cold-induced Brain Injury in Mouse8997ENMasaakiYoshimotoTakahiroKataokaTeruakiToyotaTakehitoTaguchiKiyonoriYamaokaWe 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.No potential conflict of interest relevant to this article was reported.岡山大学医学部保健学科Acta Medica Okayama1345-09481412003化学発がんの非遺伝毒性的メカニズムの解明に関する最近の動向114ENKiyonoriYamaokaKatsumiHanamotoYasuhiroInaTakahiroKataokaAtsusiKawabeMasanobuSanoAyakoUjifuku10.18926/15202本総説は,筆者らが進めている「低線量放射線の健康への影響と医療への応用」に関する研究に資するために調査した,化学発がんの非遺伝毒性的メカニズムの解明に関する最近の動向の概要についてまとめたものである。即ち,非遺伝毒性的発がんにおける細胞増殖,シトクロムP450誘導,酸化的ストレス,および遺伝子発現のそれぞれの役割,並びに量的な応答性について言及した。また,後成的発がんにおけるアポトーシス,およびギャップ結合による情報伝達のそれぞれの役割についても触れた。その結果,非遺伝毒性的な発がん物質の作用の様式とメカニズムやこれによる後成的な影響などについては解明さ
れつつあり,特に,これらの発がん物質がゲノムDNAに対し直接的な相互作用,突然変異,修飾などを行う発がん物質とは機能的に異なった作用をすることが明らかになった。また,これらは放射線発がんなど低線量放射線の健康への影響などについて研究する上で,重要な知見となっていることもわかった。No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2008Study on Effects of Low-dose Irradiation on Oxidative Damage in MiceENTakahiroKataokaNo potential conflict of interest relevant to this article was reported.Okayama University Medical SchoolActa Medica Okayama0386-300X7522021The Effects of Low-Dose-Rate γ-irradiation on Forced Swim Test-Induced Immobility and Oxidative Stress in Mice169175ENTetsuyaNakadaGraduate School of Health Sciences, Okayama UniversityTakahiroKataokaGraduate School of Health Sciences, Okayama UniversityTakaharuNomuraCentral Research Institute of Electric Power IndustryHinaShutoGraduate School of Health Sciences, Okayama UniversityJunkiYanoGraduate School of Health Sciences, Okayama UniversityShotaNaoeGraduate School of Health Sciences, Okayama UniversityKatsumiHanamotoGraduate School of Health Sciences, Okayama UniversityKiyonoriYamaokaGraduate School of Health Sciences, Okayama UniversityOriginal Article10.18926/AMO/61896The 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.No potential conflict of interest relevant to this article was reported.Okayama University Medical SchoolActa Medica Okayama0386-300X6522011An Assessment of Radioactivity Levels of 210Pb and 40K in Tobacco and Radiation Exposure from Smoking9195ENTomohiroNagamatsuAkihiroSakodaTakahiroKataokaToshiroOnoKiyonoriYamaokaOriginal Article10.18926/AMO/45267No 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 210Pb and 40K 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 210Pb and 40K in the cigarette tobacco were 0.01 and 0.3 Bq/cigarette. Since this 210Pb activity and the 210Po 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 210Pb (12%) into smoke was almost the same as that of 40K (15%), whereas the reported value for 210Po (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 210Pb and 210Po. 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.No potential conflict of interest relevant to this article was reported.