Hirayama R, Uzawa A, Matsumoto Y, Noguchi M, Kase Y, Takase N, Ito A, Koike S, Ando K, Okayasu R, Furusawa Y
Heavy-ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Radiat Prot Dosimetry. 2011 Feb;143(2-4):508-12. doi: 10.1093/rpd/ncq478. Epub 2010 Dec 9.
We studied double-strand breaks (DSB) induction and rejoining in clamped and non-clamped transplanted tumours in mice leg after exposure to 80 keV µm(-1) carbon ions and X rays. The yields of DSB in the tumours were analysed by a static-field gel electrophoresis. The OER of DSB after X rays was 1.68±0.31, and this value was not changed after 1 h rejoining time (1.40±0.26). These damages in oxygenated conditions were rejoined 60-70% within 1 h in situ. No difference was found between the exposure to X rays and carbon ions for the induction and rejoining of DSB. Thus, the values of OER and rejoined fraction after exposure to carbon ions were similar to those after X rays, and the calculated relative biological effectivenesses of carbon ion were around 1 under both oxygen conditions. The yields of DSB in vivo depend on exposure doses, oxygen conditions and rejoining time, but not on the types of radiation quality.
我们研究了80 keV µm(-1)碳离子和X射线照射后，小鼠腿部夹闭和未夹闭移植瘤中双链断裂（DSB）的诱导和修复情况。通过静态场凝胶电泳分析肿瘤中DSB的产量。X射线照射后DSB的氧增强比（OER）为1.68±0.31，再结合1小时后该值未发生变化（1.40±0.26）。在有氧条件下，这些损伤在原位1小时内60%-70%得到修复。在DSB的诱导和修复方面，X射线照射和碳离子照射之间未发现差异。因此，碳离子照射后的OER值和修复分数与X射线照射后的相似，并且在两种氧条件下计算得出的碳离子相对生物效能约为1。体内DSB的产量取决于照射剂量、氧条件和再结合时间，但不取决于辐射质量类型。
