Williams J K, Davidson S F, Johnson S G, Hsu H S, Das S K
Department of Surgery, University of Mississippi Medical Center, Jackson.
Br J Plast Surg. 1992 Jul;45(5):349-53. doi: 10.1016/0007-1226(92)90003-g.
The recent availability of a 99.9% UVA source has made possible studies that show that low energy wavelengths, previously considered innocuous, significantly affected wound healing in hairless guinea pigs. Decreased wound tensile strength and a slower rate of wound contraction in irradiated animals were among the changes noted. Because of their advocated role in the wound healing process, fibroblasts were chosen to study the effects of pure UVA exposure at a cellular level. 3H-thymidine uptake levels were measured in 8 groups of fibroblast cultures (12 samples/group). The cultures were exposed to varying concentrations of pure UVA. Previously incorporated 14C-thymidine levels were used to compensate for differences in cell numbers between samples. At a fluence of 3.65 x 10(-3) watts/cm2, a significant decrease in 3H-thymidine incorporation (compared to controls) was seen for all exposure periods and there was a dose-dependent decrease only in 3H-thymidine uptake for cells exposed to 1-4 min of UVA. Using post-exposure incubations of 2-16 h, a time-dependent recovery of 3H-thymidine uptake was also demonstrated, from 40% of control at 4 h, to 75% at 8 h, and 99% at 16 h. The near-complete recovery at 16 h was seen in exposures up to 2.73 joules/cm2 (12 min), whereas higher concentrations showed only partial recovery. These studies demonstrated the deleterious, though reversible, effects of UVA on fibroblasts and suggest a possible pathophysiologic process for UVA's effect on wound healing in this animal model.
最近有了99.9%的UVA光源，使得一些研究成为可能，这些研究表明，以前被认为无害的低能量波长，对无毛豚鼠的伤口愈合有显著影响。辐照动物伤口抗张强度降低和伤口收缩速度减慢是所观察到的变化之一。由于成纤维细胞在伤口愈合过程中所起的作用，因此选择它们来研究在细胞水平上纯UVA照射的影响。在8组成纤维细胞培养物（每组12个样本）中测量了3H-胸腺嘧啶核苷摄取水平。培养物暴露于不同浓度的纯UVA中。先前掺入的14C-胸腺嘧啶核苷水平用于补偿样本间细胞数量的差异。在3.65×10(-3)瓦/平方厘米的通量下，在所有暴露时间段内均观察到3H-胸腺嘧啶核苷掺入量显著降低（与对照相比），并且仅在暴露于UVA 1-4分钟的细胞中，3H-胸腺嘧啶核苷摄取量呈剂量依赖性降低。使用2-16小时的暴露后孵育，还证明了3H-胸腺嘧啶核苷摄取量随时间的恢复，从4小时时对照的40%，到8小时时的75%，以及16小时时的99%。在高达2.73焦耳/平方厘米（12分钟）的暴露中，16小时时几乎完全恢复，而更高浓度时仅显示部分恢复。这些研究证明了UVA对成纤维细胞具有有害但可逆的影响，并提示了在该动物模型中UVA对伤口愈合作用的可能病理生理过程。
