Epstein J H, Grekin D A
Photodermatol. 1984 Oct;1(5):237-40.
The effect of chronic applications of HN2 on acute responses of DNA synthesis to UVB radiation was studied in Uscd strain hairless mouse skin in vivo. 0.1 mg of HN2 in 95% ethyl alcohol and the diluent were applied weekly to the backs of the mice for 69 wk. The mice were then exposed to 1.98 X 10(2) J/m2 of UVB energy and were sacrified 4 hours and 48 h post-irradiation. The effects on DNA synthesis were evaluated using TdRH3 as the radioactive tracer. The results of the study revealed that the chronic HN2 applications increased the number of basal cells in the DNA synthesis phase of the mitotic cycle. This was associated with acanthosis and cellular hypertrophy. 4 h post-irradiation there was the expected depression in DNA synthesis in both the HN2- and diluent-treated mice. In addition, 48 h post-irradiation the number of basal cells synthesizing DNA was accelerated in both the HN2- and diluent-treated mice. However, it was much more noticeable in the HN2-treated animals. Whether this increased activity is related to the additive carcinogenesis generated between UVB and HN2 remains to be determined.
在体内对Uscd品系无毛小鼠皮肤研究了长期应用HN2对DNA合成急性反应于UVB辐射的影响。将0.1毫克HN2溶于95%乙醇中，每周将其及稀释剂涂抹于小鼠背部，持续69周。然后将小鼠暴露于1.98×10(2)J/m2的UVB能量下，并在照射后4小时和48小时处死。使用TdRH3作为放射性示踪剂评估对DNA合成的影响。研究结果显示，长期应用HN2增加了有丝分裂周期DNA合成期的基底细胞数量。这与棘皮症和细胞肥大有关。照射后4小时，HN2处理组和稀释剂处理组小鼠的DNA合成均出现预期的抑制。此外，照射后48小时，HN2处理组和稀释剂处理组小鼠中合成DNA的基底细胞数量均加速增加。然而，在HN2处理的动物中更为明显。这种增加的活性是否与UVB和HN2之间产生的附加致癌作用有关仍有待确定。
