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

1)在未成熟的海马神经元中，碳离子束的效率大约是X射线的10倍。X射线照射后即刻引起轴突和树突的形态变化。这些变化可能是由于X射线照射引起微丝解聚引起的。2)在严重低氧条件下，X射线的氧增强比(OER)为2.7。此外，在严重缺氧条件下24小时，计算出X射线的OER为2.6。联合应用X射线照射和mTOR抑制剂后，OER降至1.1。然而，碳离子束照射和mTOR抑制剂的联合使用并不改变OER。3)采用大鼠器官型切片培养系统，正常幼鼠小脑对C射线的RBE假设为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.