DEVELOPMENT OF THE EARLY INDICATOR FOR LATE RADIATION DAMAGE

我们以前曾描述过放射后肾近端小管细胞增殖增加和异常大核的出现。提出了一个大核细胞可能正在死亡的模型，增殖增加可能导致这些细胞有丝分裂死亡并引起功能损伤。我们采用RT-PCR方法测量了c-fos和c-myc的表达，采用照射部分与未照射部分的条带密度之比，发现c-fos和c-myc的表达在照射后很早就（24小时）增加，可能代表了DNA合成的增加。c-myc高表达的发生率随辐照剂量的增加而增加。然后在12 Gy照射后24小时测量c-fos和c-myc的表达，并在照射后9个月跟踪放射和右肾切除小鼠的BUN值。大部分c-fos和c-myc阳性小鼠BUN水平升高，而c-fos和c-myc阴性小鼠BUN水平无变化。测量c-fos和c-myc表达似乎是肾脏晚期放射损伤的潜在早期指标。

We have previously described the increased proliferation and appearance of abnormally large nuclei in renal proximal tubule cells after radiation. A model has been proposed that the large nuclear cells might be dying and the increased proliferation might lead to mitotic death of these cells and cause functional damage. We measured the expression of c-fos and c-myc taking the ratio of densities of bands for irradiated portion to unirradiated portion of the kidney after RT-PCR procedure, and found the c-fos and c-myc expression increased very early (24 hours) after irradiation, probably representing increased DNA synthesis. The incidence of high c-myc expression increased according to radiation dose from 9 to 15 Gy. Then we measured the c-fos and c-myc expression 24 hours after 12 Gy irradiation, and followed BUN values representing the renal function of irradiated and right nephrectomized mice for 9 months after irradiation. Most of c-fos and c-myc positive mice showed increased BUN level, while all mice with negative c-fos and c-myc showed no BUN change. Measuring c-fos and c-myc expression seems to be a potential very early indicator of late radiation damage of kidney.