Inter-laboratory validation of procedures for measuring 8-oxo-7,8-dihydroguanine/8-oxo-7,8-dihydro-2'-deoxyguanosine in DNA.
The aim of ESCODD, a European Commission funded Concerted Action, is to improve the precision and accuracy of methods for measuring 8-oxo-7,8-dihydroguanine (8-oxoGua) or the nucleoside (8-oxodG). On two occasions, participating laboratories received samples of different concentrations of 8-oxodG for analysis. About half the results returned (for 8-oxodG) were within 20% of the median values. Coefficients of variation (for three identical samples) were commonly around 10%. A sample of calf thymus DNA was sent, dry, to all laboratories. Analysis of 8-oxoGua/8-oxodG in this sample was a test of hydrolysis methods. Almost half the reported results were within 20% of the median value, and half obtained a CVof less than 10%. In order to test sensitivity, as well as precision, DNA was treated with photosensitiser and light to introduce increasing amounts of 8-oxoGua and samples were sent to members. Median values calculated from all returned results were 45.6 (untreated), 53.9, 60.4 and 65.6 8-oxoGua/10(6) Gua; only seven laboratories detected the increase over the whole range, while all but one detected a dose response over two concentration intervals. Results in this trial reflect a continuing improvement in precision and accuracy. The next challenge will be the analysis of 8-oxodG in DNA isolated from cells or tissue, where the concentration is much lower than in calf thymus DNA.
D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D008401:Gas Chromatography-Mass Spectrometry; D006147:Guanine / Q000031:analogs & derivatives* / Q000032:analysis*; D006801:Humans; D013058:Mass Spectrometry; D012680:Sensitivity and Specificity; D013950:Thymus Gland / Q000737:chemistry
D015415:Biomarkers; C024829:8-hydroxyguanine; D006147:Guanine; D004247:DNA; C427203:calf thymus DNA