Zhou Hongning, Randers-Pehrson Gerhard, Geard Charles R, Brenner David J, Hall Eric J, Hei Tom K
Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
Radiat Res. 2003 Nov;160(5):512-6. doi: 10.1667/rr3083.
Two conflicting phenomena, the bystander effect and the adaptive response, are important in determining biological responses at low doses of radiation and have the potential to have an impact on the shape of the dose-response relationship. Using the Columbia University charged-particle microbeam and the highly sensitive AL cell mutagenic assay, we reported previously that nonirradiated cells acquired mutagenesis through direct contact with cells whose nuclei had previously been traversed with either a single or 20 alpha particles each. Here we show that pretreatment of cells with a low dose of X rays 4 h before alpha-particle irradiation significantly decreased this bystander mutagenic response. Furthermore, bystander cells showed an increase in sensitivity after a subsequent challenging dose of X rays. Results from the present study address some of the pressing issues regarding both the actual target size and the radiation dose response and can improve on our current understanding of radiation risk assessment.
两种相互矛盾的现象，旁观者效应和适应性反应，在确定低剂量辐射的生物学反应中很重要，并且有可能影响剂量反应关系的形状。利用哥伦比亚大学的带电粒子微束和高度灵敏的AL细胞诱变试验，我们先前报道未受辐射的细胞通过与细胞核先前分别被单个或20个α粒子穿过的细胞直接接触而获得诱变作用。在此我们表明，在α粒子照射前4小时用低剂量X射线对细胞进行预处理可显著降低这种旁观者诱变反应。此外，旁观者细胞在随后受到挑战性剂量的X射线照射后敏感性增加。本研究结果解决了一些关于实际靶标大小和辐射剂量反应的紧迫问题，并可增进我们目前对辐射风险评估的理解。
