Polischouk A G, StenerlOw B, Edgren M R, Lewensohn R
Division of Medical Radiation Biology, Department of Oncology-Pathology Cancer Centre Karolinska, R8:00, SE-171 76 Stockholm Sweden.
Int J Radiat Biol. 2003 Dec;79(12):965-71. doi: 10.1080/09553000310001632912.
To compare the repair efficiency of X-ray (low linear energy transfer [LET]) and nitrogen ion (high LET)-induced single-strand breaks (SSB) in a human cell-free end-joining system.
SSB were introduced into a bacterial plasmid, pBR322, by X-rays (4 MeV photons) and nitrogen ions with an LET=125 keV micro m(-1). Repair efficiency was studied under incubation with the protein extracts from human squamous carcinoma cells, UT-SCC-5.
A several fold higher dose of nitrogen ion radiation compared with X-ray radiation was needed to induce a similar loss of supercoiled plasmid DNA. There was no difference in the repair efficiency of SSB induced by these two types of radiation.
The data indicate that X-rays at 25 Gy and nitroging ions at 100 Gy radiation doses, under condition of low scavenging capacity (10 mM Tris), induce SSB of similar complexity or, alternatively, differences in SSB complexity do not alter the repair rate.
在人无细胞末端连接系统中比较X射线（低传能线密度[LET]）和氮离子（高LET）诱导的单链断裂（SSB）的修复效率。
通过X射线（4 MeV光子）和LET = 125 keVμm⁻¹的氮离子将SSB引入细菌质粒pBR322。在与人类鳞状癌细胞UT-SCC-5的蛋白质提取物孵育的条件下研究修复效率。
与X射线辐射相比，需要几倍剂量的氮离子辐射才能诱导出类似的超螺旋质粒DNA损失。这两种类型辐射诱导的SSB的修复效率没有差异。
数据表明，在低清除能力（10 mM Tris）条件下，25 Gy的X射线和100 Gy的氮离子辐射诱导的SSB具有相似的复杂性，或者说，SSB复杂性的差异不会改变修复率。
