1992 Fiscal Year Final Research Report Summary
Study for racial difference of alpha-ray late effects --- Comparative study on Japanese and German Thorotrast patients
| Project/Area Number |
03044054
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MACHINAMI Rikuo Faculty of Medicine, The University of Tokyo, 医学部(医), 教授 (30010052)
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| Co-Investigator(Kenkyū-buntansha) |
WESCH Horst German Cancer Research Center, 放射線部, 研究員
WEGENER Kurt Stadtischen Krankenanstalten, Ludwigshafen, 病理部, 部長
KAUL Alexander Bundesamt fur Strahlenschutz, 機関長
VAN Kaick GE ドイツ癌研究センター, 放射線部, 教授
ISHIKAWA Yuichi Cancer Institute, Tokyo, 病理部, 研究員 (80222975)
MORI Takesaburo National Institute of Radiological Sciences, 特別研究員 (00124248)
IWATA Shiro Research Reactor Institute, Kyoto University, 原子炉実験所, 名誉教授 (50027398)
KOJIRO Masamichi Faculty of Medicine, Kurume University, 医学部, 教授 (90080580)
SHIGA Junji Faculty of Medicine, Teikyo University, 医学部, 教授 (10110694)
KAMIYAMA Ryuiichi Faculty of Medicine, Tokyo Medical and Dental University, 医学部, 教授 (20014095)
HATAKEYAMA Shigeru Faculty of Medicine, Tokyo Medical and Dental University, 医学部, 名誉教授 (30045926)
KAICK Gerhard van German Cancer Research Center
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| Project Period (FY) |
1991 – 1992
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| Keywords | Alpha-ray / Internal exposure / Thorotrast / Malignant tumor / Histopathological diagnosis / Epidemiology / Radon / Comparison between Japanese and German |
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| Research Abstract |
In order to compare the racial difference of alpha ray late effects between Japanese and German, 2 Japanese researchers were sent to Heidelberg and 2 German scientists were invited to Japan exchanging ideas and understanding each other.
The widely accepted concept that the alpha-emitting radionuclide radon induces lung cancers in humans has been based on the excess of lung tumors observed in underground miners extracting uranium or other substances.
Patients to whom Thorotrast was administered continuously exhale radon derived from TH 232 deposits in the body. We therefore investigated lungcancer incidence in our epidemiological follow up series in Japan. While the proportion of small-cell lung cancers considered to be related to alpha-particles was significantly increased, the overall lung cancer incidence was not significantly higher than in controls. Thus, excess lung cancers among the miners might be related to the combined effects of exposure to radon and dusts, and not solely to ra
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don.
An animal experiment has been done in Germany to confirm this hypothesis examining the effects of Thorotrast and quartz on the induction of lung tumors in rats. A significant interaction between quartz and Thorotrast(exhalation of Rn 220) has been shown in the induction of lung cancer.
Several unsolved problems in human and animal thorotrastosis have been pointed out by German study group. They are lack of precancerous lesions in most human thorotrast livers, proliferation of Kupffer cells as possibly presarcomatous lesion in men, lack of particle-storage in cells of hemangiosarcomas in men and animals, lack of primary tumors in spleen and lymph modes despite of high content of Th232 in these organs, and lack of primary tumors in the surrounding of thorotrastomas.
German study group has discovered an important fact by liver transplantation that there is a permanent lifelong translocation of a mobile fraction of Thorotrast in the body. This means that Thorotrast patients have a chronic radiation of all other organs than main storing organs such as the liver, spleen, lymph modes and bone marrow. Less
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