| Project/Area Number |
60580163
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
放射線5生物学
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| Research Institution | Faculty of Science, University of Tokyo |
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Principal Investigator |
IJIRI Ken-ichi Zoological Institute, Faculty of Science, University of Tokyo, 理学部, 助手 (40111447)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1986: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Mouse / Stem cells / Intestine / Crypt / Radiation / Radiosensitivity / Hypersensitive cells / 細胞死 |
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| Research Abstract |
Cell death,induced by a test dose of 0.5 Gy in regenerating crypts(after a priming dose of 9.0 Gy), was counted to assess when the number of radiation-hypersensitive cells was re-established. The increase in the number of both proliferative and clonogenic cells began between days 2 and 3 after 9.0 Gy. There was a difference of one day in the recovery kinetics of clonogenic cells and radiation-hypersensitive cells. In regenerating crypts, both the positions of DNA synthesizing cells and that of radiation-hypersensitive cells were also studied. The results again showed that they are two different cell populations.
The number of hypersensitive cells in crypt was studied at each time of day. At each time, mice were irradiated with 0.5 Gy and killed 3 h later. A marked diurnal variation in the number of hypersensitive cells was observed, with a peak at 09.00 and a trough at 18.00 or 21.00. When this diurnal variation was compared with that of clonogenic cells at each time of day,there seem to exist about 6 hours difference in the diurnal patterns of clonogenic cells and radiation-hypersensitive cells.
To the mice which received 9.0 Gy of gamma rays only at the lower half of the body, tritiated thymidine was repeatedly injected at 3-4 days after irradiation. After 1-2 months, mice were given a small test dose of 0.5 Gy and killed 3 h later. On the radioautograph of the crypt section, the grain count of tritium and cell death were examined. There was a good corelation between the hypersensitive cells and the cells which retained tritium for a long time.
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