Stepán Václav, Davídková Marie
Faculty of Nuclear Sciences and Physical Engineering, Department of Dosimetry and Application of Ionizing Radiation, Czech Technical University, Brehová, Prague, Czech Republic.
Radiat Prot Dosimetry. 2006;122(1-4):113-5. doi: 10.1093/rpd/ncl418. Epub 2007 Jan 17.
The yields and composition of DNA damages caused by ionising radiation depends on radiation quality. With increasing light energy transfer (LET), the proportion of isolated DNA damages with respect to cluster damaged sites decreases. Non-double strand break complex damages are induced by gamma radiation in mammalian cells at least four times more frequently that prompt DSB. The most important product of oxidative damage to DNA bases is 8-oxo-7,8-dihydroguanine (8-oxoG). The modelling of DNA damage induced by ionising radiation of different qualities was performed to assess frequencies and composition of complex damages containing 8-oxoG. The occurrence of clusters containing 8-oxoG increases from 6 to 11% for LET in the range 0.4-160 keV microm(-1). Distributions of single strand break (SSB) on opposite DNA strand around induced 8-oxoG have similar shape for different ionising radiations, but differ in their occurrence in the whole spectrum of DNA damages. The most probable configuration is a strand break localised at position +/-3 bases from 8-oxoG.
电离辐射引起的DNA损伤的产量和组成取决于辐射质量。随着线性能量传递（LET）的增加，相对于簇状损伤位点，孤立DNA损伤的比例会降低。在哺乳动物细胞中，γ辐射诱导的非双链断裂复合损伤的频率至少是即时双链断裂（DSB）的四倍。DNA碱基氧化损伤的最重要产物是8-氧代-7,8-二氢鸟嘌呤（8-氧代鸟嘌呤，8-oxoG）。对不同质量的电离辐射诱导的DNA损伤进行建模，以评估含有8-氧代鸟嘌呤的复合损伤的频率和组成。对于LET在0.4 - 160 keV·μm⁻¹范围内，含有8-氧代鸟嘌呤的簇的发生率从6%增加到11%。在诱导的8-氧代鸟嘌呤周围，单链断裂（SSB）在相反DNA链上的分布对于不同的电离辐射具有相似的形状，但在整个DNA损伤谱中的发生率有所不同。最可能的构型是在距8-氧代鸟嘌呤±3个碱基位置处的链断裂。
