放疗对肿瘤患者外周血淋巴细胞DNA损伤的研究

目的　检测放疗对肿瘤患者外周血淋巴细胞DNA损伤情况 ,为监测放射剂量对机体正常组织的损伤提供可靠的量化指标。方法　采用单细胞凝胶电泳技术 ,测定 31例放疗患者不同阶段外周血淋巴细胞DNA损伤情况 ,同时测定血清中丙二醛 (MDA)浓度和过氧化氢酶 (CAT)的活性。结果　 31例肿瘤患者中有 9例出现细胞损伤 ,其中有 3例患者拖尾长度随着照射剂量的增大而增加。本次实验最早出现慧星现象是在体外放疗剂量达 2 0Gy(体外放疗 10次 )。MDA的含量在放疗前与放疗 2 0次后 (约 4 0Gy)比较差异有显著性 ;血清中CAT活性在放疗前与放疗 10次后比较有差异 (P <0 .0 5 )。结论　一定剂量放射线对肿瘤患者外周血淋巴细胞DNA有损伤作用 ,把握好放射剂量是临床治疗的关键。

Radiotherapy effect on DNA damage of peripheral blood lymphocytes in the patients with tumor

Objective To determine the effect of radiotherapy on DNA damage of peripheral blood lymphocytes(PBL) in the patients with tumor to provide the reliable quantitative index for monitoring damage of the radiotherapy dosage to normal tissues. Methods DNA damage of PBL was detected by single cell gel electrophoresis(SCGE) in 31 cases with tumor and the concentration of Malonatealdehyde(MDA)and the activity of CAT were examined. Results 9 of 31 patients showed a damaged DNA,3 of whom had an increased DNA strand breaks(indicated by comet length) with the increasing of radiation dose. The early comet appeared when radiotherapy dose rose to 20Gy(10 times in vitro). In addition, the differences of the concentration of MDA and the activity of CAT were statistically significant(P<0.05) before and after radiotherapy. Conclusion Radiotherapy can cause DNA damage in PBL of tumor patients so the dose of radiotherapy is the key to the clinical treatment.