Contribution of indirect action to radiation-induced mammalian cell inactivation: Dependence on photon energy and heavy-ion LET
Contribution of indirect action to radiation-induced mammalian cell inactivation: Dependence on photon energy and heavy-ion LET
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DOI：
10.1667/rr3557.1
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发表时间：
2006-06-01
影响因子：
3.4
通讯作者：
Shinohara, K
中科院分区：
文献类型：
--
作者：
Ito, A;Nakano, H;Shinohara, K
OH自由基介导的电离辐射细胞灭活的间接作用的贡献进行了评估，光子的能量范围从12.4千电子伏至1.25兆电子伏和重离子的线性能量转移（LET）范围从20千电子伏/μ m至440千电子伏/μ m的应用竞争动力学分析使用OH自由基清除剂DMSO。DMSO（可保护部分）提供的最大保护水平随着光子能量的降低而降低，在12.4 keV时降至63%。对于重离子，65%的可保护部分被发现为LET约200千电子伏/亩米;以上的LET，该值保持不变。OH自由基与细胞内分子负责细胞灭活的反应速率几乎是恒定的光子灭活，而对于重离子，该速率随着LET的增加而增加，这表明高LET离子与密集产生的OH自由基的反应。使用可保护级分，将细胞杀伤分成两个组分，一个是由于间接作用，另一个是由于直接作用。在所测试的光子能量范围和离子LET范围内，间接作用的灭活效率大于直接作用的灭活效率。一个显着的贡献，直接行动也被发现在低光子能量区域的RBE增加。(c)2006年，辐射研究协会。
The contribution of indirect action mediated by OH radicals to cell inactivation by ionizing radiations was evaluated for photons over the energy range from 12.4 keV to 1.25 MeV and for heavy ions over the linear energy transfer (LET) range from 20 keV/mu m to 440 keV/mu m by applying competition kinetics analysis using the OH radical scavenger DMSO. The maximum level of protection provided by DMSO (the protectable fraction) decreased with decreasing photon energy down to 63% at 12.4 keV. For heavy ions, a protectable fraction of 65% was found for an LET of around 200 keV/mu m; above that LET, the value stayed the same. The reaction rate of OH radicals with intracellular molecules responsible for cell inactivation was nearly constant for photon inactivation, while for the heavy ions, the rate increased with increasing LET, suggesting a reaction with the densely produced OH radicals by high-LET ions. Using the protectable fraction, the cell killing was separated into two components, one due to indirect action and the other due to direct action. The inactivation efficiency for indirect action was greater than that for direct action over the photon energy range and the ion LET range tested. A significant contribution of direct action was also found for the increased RBE in the low photon energy region. (c) 2006 by Radiation Research Society.