REDUCTION OF SUNBURN DAMAGE TO SKIN BY TOPICAL APPLICATION OF VITAMIN-E ACETATE FOLLOWING EXPOSURE TO ULTRAVIOLET-B RADIATION - EFFECT OF DELAYING APPLICATION OR OF REDUCING CONCENTRATION OF VITAMIN-E ACETATE APPLIED

The skin of the skh-1 mouse after ultraviolet B (280-320 nm, UVB) irra diation shows the pathological changes typical of sunburn damage: spon giosis (edematous spaces) around some cells, necrosis of keratinocytes , giving rise to sunburn cells, inflammatory infiltration of polymorph onuclear leucocytes, etc. In our previous study, these were accompanie d by erythema, increased skin sensitivity, and edematous swelling. The topical application of tocopherol acetate (TA) immediately after the UVB exposure decreased these changes. In this paper, multiple measurem ents of the skin thick ness were made at different locations along the magnetic resonance imaging (MRI) cross-sectional image of the skin. T his permits effects to be quantified with (if desired) the contralater al half of the back serving as an internal control, either exposed (po sitive control) or unexposed (negative control). Topical application o f TA resulted in an increase in the concentration of free tocopherol i n the skin. No qualitative differences in ultrastructural appearance o f the UVB-irradiated, TA-treated skin could be discerned by careful ex amination. In vivo high resolution video microscopy of blood flow in v enules of the irradiated mouse ear revealed a large (tenfold) but not statistically significant decrease in stationary lymphocytes adhering to the venule walls. The delaying of the application of TA up to 8 hou rs after the termination of UVB irradiation still offered statisticall y significant protection as did immediate application of 5% TA in dilu ent Myritol 318 (Delios S, Henkel).