人体的循环系统里有一些有害的化学物质，血脑屏障是一道防御这些有害物质的天然屏障，但这道屏障同时也将治疗药物隔于脑外。

This barrier is a natural defence against potentially harmful chemicals floating around the body but has also stopped useful drugs reaching the brain as well.

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方法应用透射电镜观察脑胶质瘤侵袭微生态系统中血瘤屏障的超微结构改变；

Methods The ultrastructure of blood tumor barrier in gliomas was observed by transmission electronic microscope.

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糖蛋白抑制剂可促进药物通过血脑屏障，对提高脑内药物的浓度和中枢神经系统药物的生物利用度具有重要意义。

P-glycoprotein inhibitors can get drugs across the blood-brain barrier. It is of great importance to improve the blood concentration in brain and bioavailability of central nervous system drugs.

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