Tomoaki Imamura

Nara Medical University, Kashihara, Nara, Japan

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Publications (100)170.97 Total impact

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    ABSTRACT: The Yusho incident is an unprecedented mass food poisoning that occurred in Japan in 1968. It was caused by the ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds, such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The victims of Yusho have suffered from characteristic skin manifestations associated with systemic, ophthalmological, and mucosal symptoms for a long period of time. The Study Group of Yusho (the Yusho Group) has been conducting annual medical check-ups on Yusho victims for more than 45years. Since 2002, when concentrations of dioxins in the blood of Yusho patients started to be measured, the pharmacokinetics of dioxins, relationship between blood levels of dioxins and symptoms/signs in patients directly exposed to dioxins, and the adverse effects on the next generation have become dramatically clear. Herein we review recent findings of studies conducted by the Yusho Group to evaluate chronic dioxin-induced toxicity to the next generation as well as Yusho patients in comparison with a similar food mass poisoning, the Yucheng incident. Additionally, we summarized basic studies carried out by the Yusho Group to re-evaluate the mechanisms of dioxin toxicities in experimental models and various functions of the aryl hydrocarbon receptor (AhR), known as the dioxin receptor, pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Environment international 09/2015; 82. DOI:10.1016/j.envint.2015.05.004 · 5.66 Impact Factor
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    ABSTRACT: Yusho disease was first reported in October 1968 in western Japan. Although a previous survey revealed that Yusho patients have suffered from various symptoms for 40 years after the outbreak of Yusho, some symptoms could be caused by aging. Therefore, we compared the prevalence of symptoms and medical histories (symptoms or patient-reported diseases) between Yusho patients and healthy controls to demonstrate the effects of Yusho on health conditions. We conducted a survey of healthy controls who had already registered to a survey company and created a dataset of symptoms and medical histories. We then merged the healthy control data with the Yusho survey data obtained from The Ministry of Health, Labour, and Welfare of Japan. Statistical analyses were performed using a chi-square analysis for the incidence of symptoms. Symptoms included in the major diagnostic criteria for Yusho, such as pigmentation and acneform eruption, were expectedly higher in the Yusho patients than in the healthy individuals. Symptoms that could be caused by aging, such as general fatigue, arthralgia, and numbness in the extremities, were also significantly higher in the Yusho patients after adjustment for age, indicating the possibility that Yusho may cause various systemic symptoms and diseases.
    Fukuoka igaku zasshi = Hukuoka acta medica 05/2015; 106(5):85-118.
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    ABSTRACT: Half-lives of blood levels of 2,3,4,7,8-Pentachlorodibenzofuran (PeCDF) are varied in Yusho patients. The objective was to evaluate a relationship between half-lives of PeCDF levels and types of SNP rs10249788 of aryl hydrocarbon receptor (AHR) gene in 93 Yusho patients. Based on physical symptoms, age, sex, body mass index and other factors, we set up suitable calculation formulas to fit the actual PeCDF levels thorough rates of change in PeCDF. We found that patients with C/T SNP had longer half lives than patients with C/C and T/T SNPs. Patients with T/T SNP are known to express higher amount of AHR mRNAs. However, detailed analysis could not be carried out in T/T group due to a limited number of patients (n = 11). Further research is warranted to determine the cause of the longer half-lives in C/T patients.
    Fukuoka igaku zasshi = Hukuoka acta medica 05/2015; 106(5):139-43.
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    ABSTRACT: Abstract The awareness of food terrorism has increased following the September 11, 2001 terrorist attacks in New York City, United States, and many measures and policies dealing with this issue have been established worldwide. Suspected deliberate food-poisoning crimes have occurred in Japan, although they are not regarded as acts of food terrorism. One area of concern is that the small- to medium-sized companies that dominate Japan's food industry are extremely vulnerable to deliberate food poisoning. We conducted a literature research on food defense measures undertaken by the World Health Organization and in the United States and Europe. Using the Carver+Shock vulnerability assessment tool, eight food factories and related facilities in Japan were evaluated and we found the level of awareness of food defense to be low and the measures inappropriate. On the basis of this evaluation, we developed a set of guidelines that Japanese food companies can use to help develop their food defense strategies and to serve as a reference in considering specific measures.
    Foodborne Pathogens and Disease 12/2014; 11(12):953-959. DOI:10.1089/fpd.2014.1767 · 2.09 Impact Factor
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    ABSTRACT: Cedar pollinosis in Japan affects nearly 25 % of Japanese citizens. To develop a treatment for cedar pollinosis, it is necessary to understand the relationship between the time of its occurrence and the amount of airborne cedar pollen. In the spring of 2009, we conducted daily Internet-based epidemiologic surveys, which included 1453 individuals. We examined the relationship between initial date of onset of pollinosis symptoms and daily amount of airborne cedar pollen to which subjects were exposed. Approximately 35.2 % of the subjects experienced the onset of pollinosis during a one-week interval in which the middle day coincided with the peak pollen count. The odds ratio for this one-week time interval was 4.03 (95 % confidence interval: 3.34-4.86). The predicted date of the cedar pollen peak can be used to determine the appropriate date for initiation of self-medication with anti-allergy drugs and thus avoid development of sustained and severe pollinosis.
    International Journal of Environmental Health Research 04/2014; 25(1). DOI:10.1080/09603123.2014.903904 · 1.51 Impact Factor
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    Open Journal of Preventive Medicine 01/2014; 04(05):347-353. DOI:10.4236/ojpm.2014.45042
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    ABSTRACT: Objectives With increasing global interest in intentional food contamination, expert meetings have been held by the G8, while the U.S. government has proposed policies for preventing food terrorism and intentional contamination. However, Japan has no food defense policy, and some food companies are concerned about an impending terrorism and contamination crisis.Methods We developed a Food Defense Checklist for Food Producers and Processors and published the details on the website. We also developed tentative Food Defense Guidelines for Food Producers and Processors on the basis of the checklist. In this study, we tested the usability of the guidelines through a hearing survey regarding food plants. We also compared the checklist with the implementation manual for the approval system of Comprehensive Sanitation Management and Production Process (the Japanese equivalent of the HACCP).Results We organized the comments gleaned from the hearing survey and provided a detailed explanation of the guidelines. As the HACCP has been adopted by Japanese food companies, we included both precautionary measures and the HACCP perspective in the explanation regarding the rapid dissemination of information.Conclusion The guidelines are useful for Japanese food companies, and it is important to disseminate knowledge on this topic and implement food defense measures.
    [Nippon kōshū eisei zasshi] Japanese journal of public health 01/2014; 61(2):100-9.
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    ABSTRACT: Patients with a history of ischemic stroke are known to develop new ischemic stroke. While asymptomatic, the presence and progression of silent brain infarcts and white matter lesions on magnetic resonance imaging are associated with an increased risk of future strokes. Both angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are recommended for the primary and secondary prevention of stroke, but there are no direct comparisons of angiotensin-converting enzyme inhibitors versus angiotensin II receptor blockers regarding their cerebroprotective effects, including their effect on asymptomatic cerebral lesions detected by magnetic resonance imaging. Elderly (65 years or older) patients with essential hypertension who underwent cerebral magnetic resonance imaging and were found to have any cerebral ischemic lesions, such as cerebral infarction, silent brain infarct, or white matter lesion, were enrolled in this CEREBRAL study. Patients who agreed to participate were enrolled in the randomized controlled trial portion. Patients who did not agree to participate in the randomized controlled trial were enrolled in the cohort study portion. After two-years of angiotensin-converting enzyme inhibitor or angiotensin II receptor blockers treatment, follow-up magnetic resonance imaging examination will be performed. The primary end-point is the composite of (1) occurrence of a fatal or nonfatal cerebrovascular event or (2) progression of cerebrovascular lesions as evaluated by magnetic resonance imaging, including white matter lesions or silent brain infarcts. After enrollment, cognitive function was evaluated, if possible, using the Mini-Mental State Examination. Our study will clarify whether angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers are more effective for preventing primary and recurrence of ischemic stroke, including the progression of asymptomatic cerebral lesions on magnetic resonance imaging, in elderly hypertensive patients.
    International Journal of Stroke 07/2013; 10(3). DOI:10.1111/ijs.12085 · 4.03 Impact Factor
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    ABSTRACT: BACKGROUND: In 1968, many people developed dioxin poisoning (Yusho) in Japan. Ingestion of 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PeCDF) was considered to be the cause of this poisoning. Although some patients had high concentrations of 2,3,4,7,8-PeCDF in their blood, individuals' half-lives of 2,3,4,7,8-PeCDF were long. OBJECTIVES: To evaluate the relationship between clinical and laboratory parameters and the individual half-life of 2,3,4,7,8-PeCDF in blood. METHODS: Clinical and laboratory data were collected during annual check-ups from 2001 to 2008. We enrolled 71 patients, who were measured more than 3 times, and who had 2,3,4,7,8-PeCDF concentrations in blood >50pgg(-1) lipid. The half-life of 2,3,4,7,8-PeCDF for each patient was estimated using linear regression. Moreover, relationships between clinical and laboratory parameters and individual half-life were investigated by linear regression. RESULTS: A shortened individual half-life for 2,3,4,7,8-PeCDF was significantly correlated with an increased red blood cell count, increased viscous secretions from the meibomian glands, existing black comedones, and severe cedar pollen allergy. CONCLUSIONS: Symptoms that accelerate excretion of lipids from the body, such as viscous secretions from the meibomian glands, may lead to a shorter half-life of 2,3,4,7,8-PeCDF. Red blood cells are related to the half-life of 2,3,4,7,8-PeCDF. However, further studies are required to investigate the excretory mechanism of 2,3,4,7,8-PeCDF.
    Chemosphere 05/2013; 92(7). DOI:10.1016/j.chemosphere.2013.04.005 · 3.50 Impact Factor
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    ABSTRACT: The relationships among dioxin isomers are not well understood. This study aimed to clarify the relationships among isomers using two methods. First, the relationships between isomers and symptoms were analyzed by analysis of variance. Second, concentrations and half-lives were determined for each isomer in each patient, and correlation coefficients for the concentrations and half-lives among isomers were calculated. Two isomers very similar to 2, 3, 4, 7, 8-pentachlorodibenzofuran (2, 3, 4, 7, 8-PeCDF) were correlated with symptoms of Yusho disease. The correlation coefficients among three isomers similar to 2, 3, 4, 7, 8-PeCDF were very high at 0.98, indicating that there may be a mechanism which maintains constant ratios among these isomers.
    Fukuoka igaku zasshi = Hukuoka acta medica 04/2013; 104(4):78-84.
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    ABSTRACT: The Great East Japan Earthquake occurred on March 11, 2011. Tokyo and Osaka, which are located 375 km and 750 km, respectively, from the epicenter, experienced tremors of 5.0 lower and 3.0 seismic intensity on the Japan Meteorological Agency scale. The Great East Japan Earthquake was the fourth largest earthquake in the world and was accompanied by a radioactive leak at a nuclear power plant and a tsunami. In the aftermath of a disaster, some affected individuals presented to mental health facilities with acute stress disorder (ASD) and/or post-traumatic stress disorder (PTSD). However, few studies have addressed mental stress problems other than ASD or PTSD among the general public immediately after a disaster. Further, the effects of such a disaster on residents living at considerable distances from the most severely affected area have not been examined. This study aimed to prospectively analyze the effect of a major earthquake on the prevalence of insomnia among residents of Tokyo and Osaka. A prospective online questionnaire study was conducted in Tokyo and Osaka from January 20 to April 30, 2011. An Internet-based questionnaire, intended to be completed daily for a period of 101 days, was used to collect the data. All of the study participants lived in Tokyo or Osaka and were Consumers' Co-operative Union (CO-OP) members who used an Internet-based food-ordering system. The presence or absence of insomnia was determined before and after the earthquake. These data were compared after stratification for the region and participants' age. Multivariate analyses were conducted using logistic regression and a generalized estimating equation. This study was conducted with the assistance of the Japanese CO-OP. The prevalence of insomnia among adults and minors in Tokyo and adults in Osaka increased significantly after the earthquake. No such increase was observed among minors in Osaka. The overall adjusted odds ratios for the risk of insomnia post-earthquake versus pre-earthquake were 1.998 (95% CI 1.571-2.542) for Tokyo, 1.558 (95% CI 1.106-2.196) for Osaka, and 1.842 (95% CI,1.514-2.242) for both areas combined. The prevalence of insomnia increased even in regions that were at a considerable distance from the epicenter. Both adults and minors in Tokyo, where the seismic intensity was greater, experienced stress after the earthquake. In Osaka, where the earthquake impact was milder, disturbing video images may have exacerbated insomnia among adults.
    01/2013; 2(1):e2. DOI:10.2196/ijmr.2485
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    ABSTRACT: OBJECTIVES:: There is a paucity of data examining nationwide population-based incidences and outcomes of pediatric out-of-hospital cardiac arrest. The objective of this study is to describe the detailed characteristics of pediatric out-of-hospital cardiac arrest by scholastic age category and to evaluate the impact of bystander cardiopulmonary resuscitation and public access-automated external defibrillators on the 1-month survival and favorable neurological status of pediatric out-of-hospital cardiac arrest patients. DESIGN:: A nationwide, population-based, observational study. SETTING:: Nationwide emergency medical system in Japan. PATIENTS:: Out-of-hospital cardiac arrest patients aged ≤ 18 yr. MEASUREMENTS AND MAIN RESULTS:: We identified 7,624 pediatric out-of-hospital cardiac arrest patients (≤ 18 yr old) from a nationwide population-based out-of-hospital cardiac arrest database in Japan from 2005 to 2008 and stratified them into five categories by scholastic age. The overall rates of 1-month survival and favorable neurological outcomes were 11.0% and 5.1%, respectively. Bystander cardiopulmonary resuscitation resulted in a significant improvement in both 1-month survival (odds ratio 2.81; 95% confidence interval 2.30-3.44) and favorable neurological outcomes (odds ratio 4.55; 95% confidence interval 3.35-6.18). Performing public access-automated external defibrillators had a significant effect on the 1-month survival rate (odds ratio 3.51; 95% confidence interval 1.81-6.81) and favorable neurological outcomes (odds ratio 5.13; 95% confidence interval 2.64-9.96). CONCLUSIONS:: This study demonstrated that bystander cardiopulmonary resuscitation and public access-automated external defibrillators had a significant impact on the outcomes of pediatric out-of-hospital cardiac arrest. The improved survival associated with bystander cardiopulmonary resuscitation and public access-automated external defibrillators are clinically important and are of major public health importance for school-aged out-of-hospital cardiac arrest patients.
    Pediatric Critical Care Medicine 01/2013; 14(2). DOI:10.1097/PCC.0b013e31827129b3 · 2.33 Impact Factor
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    ABSTRACT: Introduction Conventional monophasic defibrillators for out-of-hospital cardiac-arrest patients have been replaced with biphasic defibrillators. However, the advantage of biphasic over monophasic defibrillation for pediatric out-of-hospital cardiac-arrest patients remains unknown. This study aimed to compare the survival outcomes of pediatric out-of-hospital cardiac-arrest patients who underwent monophasic defibrillation with those who underwent biphasic defibrillation. Methods This prospective, nationwide, population-based observational study included pediatric out-of-hospital cardiac-arrest patients from January 1, 2005, to December 31, 2009. The primary outcome measure was survival at 1 month with minimal neurologic impairment. The secondary outcome measures were survival at 1 month and the return of spontaneous circulation before hospital arrival. Multivariable logistic regression analysis was performed to identify the independent association between defibrillator type (monophasic or biphasic) and outcomes. Results Among 5,628 pediatric out-of-hospital cardiac-arrest patients (1 through 17 years old), 430 who received defibrillation shock with monophasic or biphasic defibrillator were analyzed. The number of patients who received defibrillation shock with monophasic defibrillator was 127 (30%), and 303 (70%) received defibrillation shock with biphasic defibrillator. The survival rates at 1 month with minimal neurologic impairment were 17.5% and 24.4%, the survival rates at 1 month were 32.3% and 35.6%, and the rates of return of spontaneous circulation before hospital arrival were 24.4% and 27.4% in the monophasic and biphasic defibrillator groups, respectively. Hierarchic logistic regression analyses by using generalized estimation equations found no significant difference between the two groups in terms of 1-month survival with minimal neurologic impairment (odds ratio (OR), 1.57; 95% confidence interval (CI), 0.87 to 2.83; P = 0.14) and 1-month survival (OR, 1.38; 95% CI, 0.87 to 2.18; P = 0.17). Conclusions The present nationwide population-based observational study could not confirm an advantage of biphasic over monophasic defibrillators for pediatric OHCA patients.
    Critical care (London, England) 11/2012; 16(6):R219. DOI:10.1186/cc11864
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    ABSTRACT: Background A growing elderly population along with advances in equipment and approaches for pre-hospital resuscitation necessitates up-to-date information when developing policies to improve elderly out-of-hospital cardiac arrest (OHCA) outcomes. We examined the effects of bystander type (family or non-family) intervention on 1-month outcomes of witnessed elderly OHCA patients. Methods Data from a total of 85,588 witnessed OHCA events in patients aged ≥65 years, which occurred from 2005 to 2008, were obtained from a nationwide population-based database. Patients were stratified into three age categories (65–74, 75–84, ≥85 years), and the effects of bystander type (family or non-family) on initial cardiac rhythm, rate of bystander cardiopulmonary resuscitation (CPR), and 1-month outcomes were assessed. Results The overall survival rate was 6.9% (65–74 years: 9.8%, 75–84 years: 6.9%, ≥85 years: 4.6%). Initial VF/VT was recorded in 11.1% of cases with a family bystander and 12.9% of cases with a non-family bystander. The rate of bystander CPR was constant across the age categories in patients with a family bystander and increased with advancing age categories in patients with a non-family bystander. Patients having a non-family bystander were associated with significantly higher 1-month rates of survival (OR: 1.26; 95% CI: 1.19–1.33) and favorable neurological status (OR: 1.47; 95% CI: 1.34–1.60). Conclusions Elderly patient OHCA events witnessed by a family bystander were associated with worse 1-month outcomes than those witnessed by a non-family bystander. Healthcare providers should consider targeting potential family bystanders for CPR education to increase the rate and quality of bystander CPR.
    International Journal of Emergency Medicine 11/2012; 5(1):41. DOI:10.1186/1865-1380-5-41
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    ABSTRACT: We have previously reported on both the os-teogenic potential of hydroxyapatite (HA) com-bined with bone marrow-derived mesenchymal stem cells (BMSCs) and a method involving os-teogenic matrix cell sheet transplantation of BMSCs. In the present study, we assessed the osteogenic potential of serially-passaged BMS-Cs, both in vitro and in vivo. We also assessed whether an additional cell-loading technique can regain the osteogenic potential of the constructs combined with serially-passaged BMSCs. The present study revealed that passage (P) 1 cells cultured in osteogenic-induced medium showed strong positive staining for alkaline phosphat-ase (ALP) and Alizarin Red S, whereas P3 cells showed faint staining for ALP, with no Alizarin Red S staining. Staining of P1, P2 and P3 cells were progressively weaker, indicating that the osteogenic potential of the serially-passaged rat BMSCs is lost after P3 in vitro. The in vivo study showed that little bone formation was observed in the HA constructs seeded with P3 cells, 4 weeks after subcutaneous implantation. How-ever, P3 cell/HA constructs which had incre-ased cell-loading showed abundant bone for-mation within the pores of the HA construct. ALP and osteocalcin mRNA expression in these constructs was significantly higher than that of constructs with regular cell-seeding. The pre-sent study indicates that the osteogenic poten-tial of the constructs with serially-passaged BMSCs is increased by additional cell-loading. This method can be applied to cases requiring hard tissue reconstruction, where BMSCs re-quire serial expansion of cells.
    Stem Cell Discovery 10/2012; 2(04):133-140. DOI:10.4236/scd.2012.24018
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    ABSTRACT: Background- The use and popularity of the biphasic waveform defibrillator as a replacement for the monophasic waveform defibrillator are increasing, but it is unclear whether this can improve the rate of survival among out-of-hospital cardiac arrest patients. This study aimed to verify the hypothesis that the outcome of out-of-hospital cardiac arrest patients who received defibrillation shock with the biphasic waveform defibrillator was better than that of patients who received defibrillation shock with the monophasic defibrillator. Methods and Results- This prospective, nationwide, population-based, observational study included 21 172 out-of-hospital cardiac arrest patients with initial ventricular fibrillation or pulseless ventricular tachycardia from January 1, 2005, through December 31, 2007. Defibrillation shock was performed by monophasic defibrillator on 8224 (39%) patients and by biphasic defibrillator on 12 948 (61%) patients. The rate of survival at 1 month with minimal neurological impairment was 11.6% (951/8192) in the monophasic defibrillator group and 12.8% (1653/12 928) in the biphasic defibrillator group. Hierarchical logistic regression analysis using a generalized estimation equation showed no significant difference between the biphasic and monophasic groups in 1-month survival with minimal neurological impairment (adjusted odds ratio, 1.07; 95% confidence interval, 0.91-1.26; P=0.42). Confirmatory propensity score analyses showed similar results. Conclusions- Although monophasic defibrillators are being replaced by biphasic defibrillators, our nationwide population-based observational study failed to demonstrate a statistically significant association between defibrillation waveform and 1-month survival rate with minimal neurological impairment.
    Circulation Cardiovascular Quality and Outcomes 09/2012; 5(5):689-96. DOI:10.1161/CIRCOUTCOMES.112.965319 · 5.04 Impact Factor
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    ABSTRACT: With increasing Internet coverage, the use of a web-based survey for epidemiological study is a possibility. We performed an investigation in Japan in winter 2008 using the web-based daily questionnaire for health (WDQH). The WDQH is a web-based questionnaire survey formulated to obtain information about the daily physical condition of the general public on a real-time basis, in order to study correlations between changes in physical health and changes in environmental factors. Respondents were asked whether they felt ill and had specific symptoms including fever. We analysed the environmental factors along with the health conditions obtained from the WDQH. Four factors were found to influence health: minimum temperature, hours of sunlight, median humidity and weekday or holiday. The WDQH allowed a daily health survey in the general population in real time via the Internet.
    International Journal of Environmental Health Research 09/2012; 23(3). DOI:10.1080/09603123.2012.717916 · 1.51 Impact Factor

Publication Stats

641 Citations
170.97 Total Impact Points

Institutions

  • 2008–2015
    • Nara Medical University
      • Department of Public Health, Health Management and Policy
      Kashihara, Nara, Japan
  • 2006–2009
    • Tokyo Medical University
      Edo, Tōkyō, Japan
  • 2007
    • The University of Tokyo
      • Department of Health Science and Nursing
      Tokyo, Tokyo-to, Japan
  • 2005
    • Kyushu University
      • Graduate School of Medical Sciences
      Hukuoka, Fukuoka, Japan
  • 2002
    • Ministry of Health, Labour and Welfare - Japan
      Edo, Tōkyō, Japan