Denekamp J, Stewart F A, Douglas B G
Cell Tissue Kinet. 1976 Jan;9(1):19-29. doi: 10.1111/j.1365-2184.1976.tb01250.x.
The proliferative response of mouse skin to damage caused by X-irradiation has been tested by giving repeated injections of tritiated thymidine and scoring the percentage of labelled cells in high resolution autoradiography. Four, nine and fourteen daily fractions of 300 rads of X-rays were used and labelling commenced 4 days after the last fraction. The epidermis of the upper surface and the sole of the foot were scored separately and were compared with the skin of unirradiated feet. In unirradiated skin the proliferation rate of the basal layer cells is more rapid on the sole than on the upper surface. The cell cycle times deduced from continuous labelling curves were 81 hr and 111 hr respectively and the growth fractions were 97% and85%. After irradiation with small daily doses the homeostatic response to cell killing was slow. More rapid proliferation occurred after nine fractions in the sole, but was not apparent in the skin of the upper surface until fourteen fractions had been given. After fourteen fractions the cell cycle time was about 24 hr on both surfaces and the growth fraction was about 90%. The initial labelling index after a single thymidine injection was a poor measure of proliferation rate. The delay in the time of onset of faster proliferation is similar, both qualitatively and quantitatively, to that measured previously from the additional dose increments needed if large doses were given at different times after the multifraction treatments (Denekamp, 1973).
通过反复注射氚标记的胸腺嘧啶核苷，并在高分辨率放射自显影中对标记细胞的百分比进行评分，来测试小鼠皮肤对X射线照射造成损伤的增殖反应。使用了每日分次给予300拉德X射线，共4次、9次和14次，在最后一次分次照射后4天开始标记。分别对足背和足底的表皮进行评分，并与未照射足部的皮肤进行比较。在未照射的皮肤中，足底基底层细胞的增殖速率比足背更快。从连续标记曲线推导得出的细胞周期时间分别为81小时和111小时，生长分数分别为97%和85%。每日给予小剂量照射后，对细胞杀伤的稳态反应缓慢。在足底，9次分次照射后出现更快的增殖，但在足背皮肤中，直到给予14次分次照射后才明显。14次分次照射后，两个表面的细胞周期时间约为24小时，生长分数约为90%。单次注射胸腺嘧啶核苷后的初始标记指数并不能很好地衡量增殖速率。更快增殖开始时间的延迟，在定性和定量方面，都与之前从多分次治疗后不同时间给予大剂量时所需的额外剂量增量所测量的结果相似（德内坎普，1973年）。
