title: Induction of cyclobutane pyrimidine dimers, pyrimidine(6-4)pyrimidone photoproducts, and Dewar valence isomers by natural sunlight in normal human mononuclear cells.
abstract: Immunocytochemistry was used for the direct measurement of cyclobutane pyrimidine dimers, (6-4) photoproducts, and Dewar isomers in normal human mononuclear cells following irradiation by natural sunlight or by a FS20 broad spectrum UVB sunlamp. The induction of each type of photoproduct was detected following 30-60 min sunlight exposure or with FS20 fluences as low as 50-100 Jm-2. With increasing FS20 fluences, there was a dose-dependent increase in the binding of pyrimidine dimer, (6-4) photoproduct, and Dewar isomer-specific monoclonal antibodies. The relative ratio of Dewar isomer to (6-4) photoproduct antibody binding sites was much higher following exposure to natural sunlight than to broad spectrum UVB. With the (6-4) monoclonal antibody, a small increase in binding sites was evident after a 1-h exposure to natural sunlight. This remained relatively constant with further exposure. These results are consistent with the hypothesis that, following irradiation with natural sunlight, the majority of (6-4) photoproducts are converted into Dewar valence isomers.
authors.affiliation: MRC Cell Mutation Unit, Sussex University, Falmer, Brighton, United Kingdom.
authors.forename: P H
authors.initials: PH
authors.lastname: Clingen
authors.forename: C F
authors.initials: CF
authors.lastname: Arlett
authors.forename: L
authors.initials: L
authors.lastname: Roza
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: O
authors.initials: O
authors.lastname: Nikaido
authors.forename: M H
authors.initials: MH
authors.lastname: Green
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000097:blood* / Q000528:radiation effects*; D004249:DNA Damage; D006801:Humans; D007150:Immunohistochemistry; D007536:Isomerism; D007963:Leukocytes, Mononuclear / Q000378:metabolism* / Q000528:radiation effects*; D010777:Photochemistry; D011740:Pyrimidine Dimers / Q000096:biosynthesis / Q000097:blood*; D013472:Sunlight / Q000009:adverse effects*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D000911:Antibodies, Monoclonal; D011740:Pyrimidine Dimers; C058406:pyrimidine-pyrimidone dimer; D004247:DNA