| Project/Area Number |
13680632
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
環境影響評価(含放射線生物学)
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| Research Institution | Nara Medical University |
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Principal Investigator |
MORI Toshio Nara Medical University, Medicine, Associate professor, 医学部, 助教授 (10115280)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | UV / cyclobutane pyrimidine dimer / (6-4) photoproduct / micropore UV irradiation / apoptosis / nucleotide excision repair / DNA damage / Cockayne syndrome / UVC / マイクロビーム / ミクロブタン型ダイマー / 6-4型ダイマー / UV / 紫外線局所照射 / 色素性乾皮症 / XP / PCNA |
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| Research Abstract |
We have recently developed a micropore ultraviolet (UV) irradiation technique. An isopore membrane filter with 3μm diameter pores shields UVC radiation from cultured human fibroblasts, leading to partial irradiation within the cells with an average of about 3 exposed areas per nucleus. The present study addressed the question of whether the spatial distribution of DNA damage within a cell nucleus is important in triggering UV-induce cytotoxicity. We have examined whether there are differences incytotoxicity between partially UV-irradiated cells and uniformly irradiated cells after equal amounts of DNA damage were induced in the cell nuclei. We first determined DNA damage formation in normal human fibroblasts using anenzyme-linked immunosorbent assay. We found that 5 J per m^2 UV irradiation produced an equivalent amount of cyclobutane pyrimidine dimers and (6-4) photoproducts per cell as 100 J per m^2 with the membrane filter shield. At those doses, we found that both types of UV irradiation induced similar levels of cytotoxicity as assessed by an MTS assay. Both types of UV irradiated cells also had similar cell-cycle distribution and apoptosis as measured by flowcytometry. Moreover, no significant differences in repair kinetics for either type of photolesion were observed between the two different UV treatments. Similar results were obtained in Cockayne syndrome cells that are defective in transcription-coupled nucleotide excision repair Present results indicate that in the range of photoproducts studied, the spatial distribution of DNA damage within a cell is less important than the amount of damage in triggering UV-induced cytotoxicity.
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