放射性核種の摂取に対する体内動態解析とその内部被曝評価への応用

学位の種別:課程博士University of Tokyo(東京大学

Androgen in postmenopausal women

Menopausal symptoms, bone loss, changes in lipid profiles and reduction of insulin sensitivity due to an abrupt decrease in circulating estrogen level are well known in women during the menopausal transition. On the other hand, the effect of androgen on women’s health has not been fully elucidated. Circulating levels of testosterone and dehydroepiandrosterone sulfate (DHEA-S) gradually decrease with age in postmenopausal women, although transient increases have been observed during the menopausal transition. High testosterone level has been suggested to be associated with increased risk of cardiovascular disease, increased triglyceride, insulin resistance and increase in the risk of developing breast cancer in postmenopausal women. Circulating DHEA-S level does not affect the risk of cardiovascular disease, mortality or lipid profiles in women. Female androgen insufficiency, which is characterized by the presence of reduced androgen level in circulation, leads to an impairment in sexual drive, reduced libido, depressed mood, and signs and symptoms of limited androgen exposure such as decreased muscle mass, reduced bone density and decreased sense of well-being. An appropriate level of androgen may play important roles in metabolic, psychological and sexual functions in women. In addition, the roles of testosterone and DHEA-S in women’s health may be different

Androgen in postmenopausal women

Menopausal symptoms, bone loss, changes in lipid profiles and reduction of insulin sensitivity due to an abrupt decrease in circulating estrogen level are well known in women during the menopausal transition. On the other hand, the effect of androgen on women’s health has not been fully elucidated. Circulating levels of testosterone and dehydroepiandrosterone sulfate (DHEA-S) gradually decrease with age in postmenopausal women, although transient increases have been observed during the menopausal transition. High testosterone level has been suggested to be associated with increased risk of cardiovascular disease, increased triglyceride, insulin resistance and increase in the risk of developing breast cancer in postmenopausal women. Circulating DHEA-S level does not affect the risk of cardiovascular disease, mortality or lipid profiles in women. Female androgen insufficiency, which is characterized by the presence of reduced androgen level in circulation, leads to an impairment in sexual drive, reduced libido, depressed mood, and signs and symptoms of limited androgen exposure such as decreased muscle mass, reduced bone density and decreased sense of well-being. An appropriate level of androgen may play important roles in metabolic, psychological and sexual functions in women. In addition, the roles of testosterone and DHEA-S in women’s health may be different

Difference in the Cesium Body Contents of Affected Area Residents Depending on the Evacuation Timepoint Following the 2011 Fukushima Nuclear Disaster

Estimating the internal thyroid dose received by residents involved in the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been a challenging task because of the shortage of direct human measurements related to the largest contributing radioisotope to the dose, I. In a previous dose estimation, we used the results of whole-body counter (WBC) measurements targeting Cs and Cs, based on the assumption that these radioisotopes were incorporated at the same time as I in the early phase of the accident. The main purpose of this study was to clarify whether the trace of the early intake remained in the WBC measurements that were started several months after the accident. In the present work, WBC data of 1,639 persons from Namie town, one of the heavily contaminated municipalities, were analyzed together with their evacuation behavior data. The results demonstrated that the cesium detection rate in the WBC results was several times higher in the late evacuees [who evacuated outside the 20-km radius of the FDNPP at 3:00 p.m. (Japanese Local Time) on 12 March or later] compared to the prompt evacuees (who evacuated before 3:00 p.m. on 12 March). Among the adults, the cesium detection rates (and the 90th percentile values of the Cs intake) of the prompt and late evacuees were about 20% (5.4 × 10 Bq) and 60% (1.6 × 10 Bq), respectively. Approximately 20% of the individuals analyzed were categorized as late evacuees. These differences in cesium would be caused by exposure to the radioactive plume in the afternoon on 12 March, which was likely to influence the late evacuees. On the other hand, the intake on 15 March, when the largest release event occurred, was expected to be relatively small for Namie town's residents. In conclusion, the trace of the early intake remained in the WBC measurements, although this would not necessarily be true for all subjects. The results obtained from this study would provide useful information for the reconstruction of the early internal thyroid doses from radioiodine in the future

Early Intake of Radiocesium by Residents Living Near the Tepco Fukushima Dai-ichi Nuclear Power Plant After the Accident. Part 2: Relationship Between Internal Dose and Evacuation Behavior in Individuals

The Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident exposed members of the public to radiation. This study analyses the relation between personal behavior data obtained from 112 out of 174 subjects who underwent whole-body measurements by the National Institute of Radiological Sciences (NIRS) during the period from 27 June to 28 July 2011 and their committed effective doses (CEDs) from Cs and Cs. The whereabouts of the 112 persons living in municipalities near the FDNPP (mainly, Namie town) on several days in March 2011 are graphed on maps. It was confirmed that most subjects started evacuation promptly and had left the 20-km-radius of the FDNPP by the end of 12 March. The individual CEDs were poorly correlated with the person's distances from the FDNPP at any day in March. Meanwhile, the percentage of persons remaining within the 20-km radius of the FDNPP was 100% at 16:00 on 12 March and 42.9% at 0:00 on 15 March for those with CEDs > 0.1 mSv, whereas the corresponding values were much lower for those with CEDs ≤ 0.1 mSv. This suggests that the time of evacuation would be one of the crucial factors for the early intake; however, more personal behavior data are needed to be analyzed to clarify the relevance to the individual internal dose