| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2012: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2011: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2010: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Research Abstract |
Cerebral dysfunction is one of the major concerns associated with radiotherapy of brain tumors and acute lymphoblastic leukemia. Side effects such as learning impairment and cognitive dysfunction are reported on the central nervous system (CNS) tissue after exposure to radiation during cancer therapy. This study investigated early effects on the cognitive function and microvessel density (MVD) after local brain irradiation with carbon ions using mice. Irradiation was carried out a 290 MeV/u 5 mm-SOBP carbon beam produced by the Heavy Ions Medical Accelerator in Chiba, Japan. The whole of brain was irradiated, excluding eyes and brain stem. The mice irradiated with single dose of 10-30 Gy showed deficit in short-term working memory assessed at 36 hr after irradiation, whereas mice receiving carbon irradiation showed no deficit in long-term memory.Histopathological observation revealed no abnormal finding in the irradiated brain at 1 week after irradiation, although irradiated mice showed marked neuronal degeneration at the hippocampus within CA1 to CA3 layers at 16 weeks after irradiation. In the irradiated group, neuronal cells in the hippocampal CA1-3 areas were reduced by 30-49%. However, MVD of the hippocampus and cerebral cortex decreased rapidly from 1 week after irradiation. The cerebral MVD also declined from 1 to 12 weeks and radiation vasculopathy generally was dose and time dependent. It is possibility that radiation-induced degeneration of neuronal cells caused by same mechanism as the ischemia follow vasculature breakdown.
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