title: Exposure to ultraviolet B radiation increases the tolerance of mouse skin to daily X irradiation.
abstract: Based on the hypothesis that acceleration of repopulation in skin during fractionated irradiation is triggered by an inflammatory response of the dermis to radiation-induced epidermal hypoplasia, we produced a mild erythema by exposure to UVB radiation before applying different X-irradiation schedules. At different times ranging from 6 h to 14 days after a single exposure to UVB radiation which caused a distinct erythema, a 2-cm skin field on the legs of mice was irradiated with either different single doses or five daily fractions of 3 Gy followed by different single top-up doses of 300 kV X rays. Skin reactions were scored daily for 4 weeks and the occurrence of moist desquamation was taken to construct dose-response curves and to calculate ED50 values. Five days after exposure to UVB radiation and later, radioresistance of epidermis to single and fractionated X irradiation was significantly increased. Results were analyzed using the linear-quadratic formalism to identify possible mechanisms for this UV-radiation-induced radioresistance. The data suggest that exposure to UVB radiation led to a gradual increase in the number of epidermal stem cells and their repopulation rate.
authors.affiliation: Department of Radiation Biology, St. Bartholomew's Medical College, London, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Shirazi
authors.forename: K
authors.initials: K
authors.lastname: Liu
authors.forename: K R
authors.initials: KR
authors.lastname: Trott
mesh_terms: D000818:Animals; D001345:Autoradiography; D002455:Cell Division / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects; D004487:Edema; D004847:Epithelial Cells; D004848:Epithelium / Q000528:radiation effects; D004890:Erythema; D005260:Female; D015603:Keratinocytes / Q000166:cytology / Q000528:radiation effects; D051379:Mice; D008815:Mice, Inbred Strains; D011836:Radiation Tolerance; D012867:Skin / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014316:Tritium; D014466:Ultraviolet Rays; D014965:X-Rays
chemical_list: D014316:Tritium; D004247:DNA; D013936:Thymidine