title: Multiple small exposures of filtered mid-UV radiation increase the resistance of Chinese hamster cells to far-UV, mid-UV and filtered mid-UV radiation.
abstract: The response of Chinese hamster cells (V79-MI2G) to multiple, low doses of filtered mid-UV radiation (wavelengths longer than 300 nm) were examined over an exposure period of 30 days. Cell survival and the induction of mutation at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus using resistance to 6-thioguanine (TG) were the endpoints in this study. With increasing total accumulated dose given at 500 J/m2/day as a single short exposure, an increased resistance to cell killing was observed. This increase in resistance to cell killing was accompanied by a gradual decrease in sensitivity to the induction of mutants resistant to 6-TG. Above total accumulated doses of 5000 J/m2 the frequency of 6-TG resistance did not increase. After multiple doses of filtered mid-UV radiation the cells became more resistant to subsequent challenges with acute doses of far-UV, mid-UV or filtered mid-UV. The increased resistance to the cell killing action and to the mutation induction by UV suggests that during exposure to low, multiple doses of filtered mid-UV radiation the cells become adapted to the damaging effects of filtered mid-UV radiation.
authors.affiliation: USC School of Medicine, Radiation Oncology Department, Southern California Cancer Center, Los Angeles.
authors.forename: M
authors.initials: M
authors.lastname: Osmak
authors.forename: A
authors.initials: A
authors.lastname: Han
authors.forename: M
authors.initials: M
authors.lastname: Ikebuchi
authors.forename: C K
authors.initials: CK
authors.lastname: Hill
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D009154:Mutation; D011829:Radiation Dosage; D011836:Radiation Tolerance; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase