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标题：Repair Kinetics of DNA-DSB Induced by X-rays or Carbon Ions under Oxic and Hypoxic Conditions
其他标题：Repair Kinetics of DNA-DSB Induced by X-rays or Carbon Ions under Oxic and Hypoxic Conditions
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作者：Ryoichi HIRAYAMA ; Yoshiya FURUSAWA ; Takeshi FUKAWA 等
期刊名称：Journal of Radiation Research
印刷版ISSN：0449-3060
电子版ISSN：1349-9157
出版年度：2005
卷号：46
期号：3
页码：325-332
DOI：10.1269/jrr.46.325
摘要：We studied the relation between initial DNA double-strand breaks (DNA-DSB) and the rejoining kinetics of the strand breaks, as well as the OER (oxygen enhancement ratio) after low- and high-LET (linear energy transfer) radiations. CHO cells were exposed to 200 kVp X-rays or 80 keV/μm carbon ions under oxic and hypoxic conditions. DNA-DSB in the cells were analyzed by a static-field gel electrophoresis (SFGE). The kinetics of the rejoining could be described by a sum of fast and slow components. The initial released DNA after X-ray irradiation was higher for cells irradiated under an oxic condition than that under a hypoxic condition. The OER of DNA-DSB after X-ray irradiation was 5.7. This value decreased rapidly to be 3.4 with the fast component by 15 minutes. On the other hand, the OER of DNA-DSB after carbon ion irradiation was 2.2, and this value was not changed by rejoining incubation. The OER values for cell killing were 2.8 and 1.8 after X-ray and carbon ion irradiations, respectively. These values matched to the OER for DNA-DSB with complete rejoining. We conclude that the rejoining of DNA-DSB is an important factor in the mechanism of the oxygen effect.
关键词：Oxygen effect; DNA double-strand breaks; Rejoining kinetics; Carbon ions