Molecular biological investigation about the effect of heavy-ion beam on normal brain

1)碳离子束对未成熟海马神经元的作用比X射线强10倍。X射线照射后立即引起轴突和树突的形态学变化。2）在严重缺氧条件下1h，X射线的氧增强比（OER）为2.7。在重度低氧条件下24小时，X线的OER为2.6。通过X射线照射和mTOR抑制剂的组合使用，OER降低至1.1。然而，联合使用碳离子束照射和mTOR照射并没有改变OER。3）采用大鼠器官型切片培养系统，在正常幼年大鼠小脑中，C-束对X射线的RBE被假定为1.4。

1) Carbon-ion beams were about 10-fold more effective than X-rays in immature hippocampal neurons. X-irradiation immediately induced morphological changes in axons and dendrite. These changes seemed to be caused by x-irradiation evoking depolymerization of microfilament.2) Under severe hypoxic condition for 1 hour, oxygen enhancement ratio (OER) of X-ray was calculated as 2.7. Also, Under severe hypoxic condition for 24 hour, OER of X-ray was calculated as 2.6. OER was decreased to 1.1 by the combination use of X-ray irradiation and mTOR inhibitor. However, OER was not changed by combination use of carbon-ion beam irradiation and mTOR inhibitor.3) The RBE of C-beams to X-rays in the normal cerebellum of infant rats with rat organotypic slice culture system was assumed to be 1.4.