| Co-Investigator(Kenkyū-buntansha) |
ABE Hirohiko Kurume University, School of Med., Ass. Professor, 医学部, 助教授 (20080658)
KOJIRO Masamichi Kurume University, School of Med., Professor, 医学部, 教授 (90080580)
IWATA Shiro Kyoto University, Res. Reactor Inst., Professor, 原子炉実験所, 教授 (50027398)
KATO Yoshio National Institute of Radiological Sciences, Training School, Head of the Dept., 養成訓練部, 部長 (30161128)
MORI Takesaburo National Institute of Radiological Sciences, Div. of Physiol. & Pathol., Chief R, 生理病理研究部, 主任研究官 (00124248)
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| Research Abstract |
1. Epidemiological study : The mortality rate of hepatocellular carcinoma, liver cirrhosis, leukemia, Thorotrast sarcoma, epilepsy, extrahepatic cholangiocarcinoma and malignant peritoneal tumor was significantly higher in Thorotrast-administered patients than in control series. In addition, the high incidence of inflammatory diseases suggests the disturbance of immune system by Thorotrast deposition. Median survival time was decreased in proportion to the injection amounts of Thorotrast.
2. Dosimetry : It was estimated that dose rate in alveolar region was about 1 rad/y by concentration of thoron in expiration of Thorotrast-administered patients. It seems that the relationship between the occurrence of lung cancer by high LET radiation and absorbed dose must be further investigated. Thorium content detection method was determined by the neutron activation analysis using tissue samples of Thorotrast-administered patients.
3. Clinical study : In Thorotrast-administered patients, the funct
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ion of the reticuloendothelial system, especially phagocytic activity, was depressed and endotoxemia was frequently revealed. The increase of type III collagen in the portal area and sinusoidal wall and type I collagen along the liming plate was observed in Thorotrast liver fibrosis.
4. Pathological study : The majority (95.4%) of Thorotrast-related cholangiocarcinoma was located in the middle-peripheral portion of the liver. In contrast, 77.7% of the non-Thorotrast-related cases were located in the hilar region. This prominent difference in tumor location suggests that Thorotrast most likely affects relatively small bile ducts in the periphery or middle portion of the liver. Thorotrast deposition in the spleen was predominantly in the white pulp, marginal zone and in/around the trabecula in the early stage. It is thought that the fibrosis developed from these regions and interconnected each other. In the advanced stage, these spleens became fibrotic shrunken state. Thus, the hypofunction of the spleen such as the increase of erythrocytes having Howell-Jolly bodies appears in these advanced states. In a small number of Thorotrast-administered patients, the cases with splenomegaly were highly complicated by esophageal variceal bleeding as the cause of death. Less
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