title: Cyclobutane thymidine dimers are present in human urine following sun exposure: quantitation using 32P-postlabeling and high-performance liquid chromatography.
abstract: Cyclobutane thymidine dimer (T=T) is the major DNA photoproduct formed in human skin after solar radiation. We have developed a 32P-postlabeling method suitable for quantitating T=T in human urine with a detection limit of about 0.5 fmol per 10 microl urine. The method was used in the present study to measure the daily T=T urinary level of two volunteers over a 15 d period, including frequent sun exposures ranging from 0 to 5 h daily. T=T was not detected before or immediately (4 h) after the initial sun exposure but was first observed in urine samples collected 18 h after the initial exposure. Thereafter, urinary T=T levels gradually increased up to a peak reached about 3 d after the maximum sun exposure. The levels decreased during the following days but were still detectable 8 d after the last sun exposure. About 70-75% decrease in excreted T=T was observed after 8 d. The T=T levels measured in urine were lower but in the same order of magnitude as the levels expected after a theoretical calculation based on previous published results and reasonable assumptions. This study shows the occurrence of cyclobutane thymidine dimers in human urine after skin exposure to solar radiation.
authors.affiliation: Department of Biosciences at Novum, Karolinska Institute, Huddinge, Sweden.
authors.forename: F
authors.initials: F
authors.lastname: Le Curieux
authors.forename: K
authors.initials: K
authors.lastname: Hemminki
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003404:Creatinine / Q000032:analysis / Q000652:urine; D004247:DNA / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D010761:Phosphorus Radioisotopes; D011740:Pyrimidine Dimers / Q000032:analysis* / Q000652:urine*; D012867:Skin / Q000528:radiation effects*; D013471:Sunburn / Q000175:diagnosis* / Q000652:urine; D013472:Sunlight / Q000009:adverse effects*
chemical_list: D010761:Phosphorus Radioisotopes; D011740:Pyrimidine Dimers; D004247:DNA; D003404:Creatinine