ARYLSULFATASE A ACTIVITY/GENETIC ALTERATION AND RADIATION INDUCED LEUKOENCEPHALOPATHY

辐射敏感性作为生物学因素之一，在成人放射性脑白质病中起着重要作用。我们推测芳基硫酸酯酶A的活性可能与脑的辐射敏感性有关，因为最近的研究揭示了芳基硫酸酯酶A的活性可能与脱髓鞘疾病有关。在征得知情同意后，用硫酸盐对硝基阴离子进行人工底物法测定血液中芳基硫酸酯酶A的活性。此外，还进行了22q13(E2400-PA2723)的DNA分析，以检测芳基硫酸酯酶A基因的异常。本文比较了20例正常志愿者和20例脑胶质瘤患者的芳基硫酸酯酶活性。芳基硫酸酯酶A活性在正常范围内(60~144mol/mg蛋白/h)，两组间差异无统计学意义。并比较了放射治疗后脑白质病变患者和无脑白质病变的脑胶质瘤患者的芳基硫酸酯酶A活性。染色体22q13上的DNA分析也未发现基因异常。这些结果表明，芳基硫酸酯酶A活性与放射治疗后脑白质病变的发生无直接关系。我们已经完成了全脑照射对体神经干细胞影响的初步实验。进一步的实验可能会阐明体细胞神经干细胞在放射性脑白质病变中的作用。

As one of the biological factors, radiation sensitivity plays a critical role in radiation induced leukoencephalopathy in adults. We hypothesized that arylsulfatase A activity might be involved in radiation sensitivity of the brain because recent studies disclosed that arylsulfatase A activity may related to demyelinating disease.After receiving informed consent, blood arylsulfatase A activity was measured by artificial substrate method using Pnitrocathecole sulfate. Furthermore, DNA analysis at 22ql3 (E2400-PA2723) were performed to detect abnormality in arylsulfatase A gene. Arylsulfatase activity was compared between 20 normal volunteer and 20 patients with gliomas. Arylsulfatase A activity was within normal range (60- 144 mol/mg protein/h) and there was no significat difference between two groups. Arylsulfatase A activity was also compared between patients with leukoencephalopathy after radiation therapy and patients without leukoencephalopathy in gliomas. There was no significant difference between them.DNA analysis on chromosome 22q13 also showed no gene abnormality. These results indicated that arylsulfatase A activity was not directly related to the induction of leukoencephalopathy after radiation therapy. We have finished a preliminary experiment for the effect of whole brain radiation on somatic neuronal stem cells. Further experiments might clarify the role of somatic neuronal stem cells on radiation induced leukoencephalopathy.