title: Measuring oxidative damage to DNA and its repair with the comet assay.
abstract: BACKGROUND
  Single cell gel electrophoresis, or the comet assay, was devised as a sensitive method for detecting DNA strand breaks, at the level of individual cells. A simple modification, incorporating a digestion of DNA with a lesion-specific endonuclease, makes it possible to measure oxidised bases.
  
  
  METHODS
  With the inclusion of formamidopyrimidine DNA glycosylase to recognise oxidised purines, or Nth (endonuclease III) to detect oxidised pyrimidines, the comet assay has been used extensively in human biomonitoring to monitor oxidative stress, usually in peripheral blood mononuclear cells.
  
  
  CONCLUSIONS
  There is evidence to suggest that the enzymic approach is more accurate than chromatographic methods, when applied to low background levels of base oxidation. However, there are potential problems of over-estimation (because the enzymes are not completely specific) or under-estimation (failure to detect lesions that are close together). Attempts have been made to improve the inter-laboratory reproducibility of the comet assay.
  
  
  CONCLUSIONS
  In addition to measuring DNA damage, the assay can be used to monitor the cellular or in vitro repair of strand breaks or oxidised bases. It also has applications in assessing the antioxidant status of cells. In its various forms, the comet assay is now an invaluable tool in human biomonitoring and genotoxicity testing. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.
authors.affiliation: Department of Nutrition, University of Oslo, Norway. Electronic address: a.r.collins@medisin.uio.no.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Collins
mesh_terms: D000818:Animals; D020552:Comet Assay / Q000379:methods*; D004247:DNA / Q000032:analysis*; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D006801:Humans
chemical_list: D004247:DNA
keywords: Antioxidant defence; Base oxidation; Comet assay; DNA damage; DNA repair