title: Analysis of urinary 8-oxo-7,8-dihydro-purine-2'-deoxyribonucleosides by LC-MS/MS and improved ELISA.
abstract: Non-invasive monitoring of oxidative stress is highly desirable. Urinary 7,8-8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a biologically relevant and convenient analytical target. However, immunoassays can over-estimate levels of urinary 8-oxodG. Measurement of more than one DNA oxidation product in urine would be advantageous in terms of mechanistic information. Urines samples were analysed for 8-oxodG by solid-phase extraction/LC-MS/MS and ELISA. The solid-phase extraction/LC-MS/MS assay was also applied to the analysis of urinary 7,8-dihydro-8-oxo-2'-deoxyadenosine (8-oxodA). Concurring with previous reports, urinary 8-oxodG measured by ELISA was significantly higher than levels measured by LC-MS/MS. However, apparent improvement in the specificity of the commercially available Japanese Institute for the Control of Ageing (JaICA) ELISA brought mean LC-MS/MS and ELISA measurements of urinary 8-oxodG into agreement. Urinary 8-oxodA was undetectable in all urines, despite efficient recovery by solid phase extraction. Exploitation of the advantages of ELISA may be enhanced by a simple modification to the assay procedure, although chromatographic techniques still remain the 'gold standard' techniques for analysis of urinary 8-oxodG. Urinary 8-oxodA is either not present or below the limit of detection of the instrumentation.
authors.affiliation: Department of Cancer, Radiation and Oxidative Stress Section, Studies and Molecular Medicine, University of Leicester, Leicester Royal Infirmary, University Hospitals of Leicester, Leicester, UK. mde2@le.ac.uk
authors.forename: Mark D
authors.initials: MD
authors.lastname: Evans
authors.forename: Rajinder
authors.initials: R
authors.lastname: Singh
authors.forename: Vilas
authors.initials: V
authors.lastname: Mistry
authors.forename: Karendeep
authors.initials: K
authors.lastname: Sandhu
authors.forename: Peter B
authors.initials: PB
authors.lastname: Farmer
authors.forename: Marcus S
authors.initials: MS
authors.lastname: Cooke
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002853:Chromatography, Liquid; D004249:DNA Damage; D003839:Deoxyadenosines / Q000652:urine*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000652:urine; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D018384:Oxidative Stress; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003839:Deoxyadenosines; C078251:2'-deoxy-7,8-dihydro-8-oxoadenosine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine