title: Inter-laboratory variation in DNA damage using a standard comet assay protocol.
abstract: There are substantial inter-laboratory variations in the levels of DNA damage measured by the comet assay. The aim of this study was to investigate whether adherence to a standard comet assay protocol would reduce inter-laboratory variation in reported values of DNA damage. Fourteen laboratories determined the baseline level of DNA strand breaks (SBs)/alkaline labile sites and formamidopyrimidine DNA glycosylase (FPG)-sensitive sites in coded samples of mononuclear blood cells (MNBCs) from healthy volunteers. There were technical problems in seven laboratories in adopting the standard protocol, which were not related to the level of experience. Therefore, the inter-laboratory variation in DNA damage was only analysed using the results from laboratories that had obtained complete data with the standard comet assay protocol. This analysis showed that the differences between reported levels of DNA SBs/alkaline labile sites in MNBCs were not reduced by applying the standard assay protocol as compared with the laboratory's own protocol. There was large inter-laboratory variation in FPG-sensitive sites by the laboratory-specific protocol and the variation was reduced when the samples were analysed by the standard protocol. The SBs and FPG-sensitive sites were measured in the same experiment, indicating that the large spread in the latter lesions was the main reason for the reduced inter-laboratory variation. However, it remains worrying that half of the participating laboratories obtained poor results using the standard procedure. This study indicates that future comet assay validation trials should take steps to evaluate the implementation of standard procedures in participating laboratories.
authors: Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen K, Denmark.
authors: Lykke
authors: L
authors: Forchhammer
authors: Clara
authors: C
authors: Ersson
authors: Steffen
authors: S
authors: Loft
authors: Lennart
authors: L
authors: Möller
authors: Roger W L
authors: RW
authors: Godschalk
authors: Frederik J
authors: FJ
authors: van Schooten
authors: George D D
authors: GD
authors: Jones
authors: Jennifer A
authors: JA
authors: Higgins
authors: Marcus
authors: M
authors: Cooke
authors: Vilas
authors: V
authors: Mistry
authors: Mahsa
authors: M
authors: Karbaschi
authors: Andrew R
authors: AR
authors: Collins
authors: Amaya
authors: A
authors: Azqueta
authors: David H
authors: DH
authors: Phillips
authors: Osman
authors: O
authors: Sozeri
authors: Michael N
authors: MN
authors: Routledge
authors: Kirsty
authors: K
authors: Nelson-Smith
authors: Patrizia
authors: P
authors: Riso
authors: Marisa
authors: M
authors: Porrini
authors: Giuseppe
authors: G
authors: Matullo
authors: Alessandra
authors: A
authors: Allione
authors: Maciej
authors: M
authors: Stępnik
authors: Maciej
authors: M
authors: Steepnik
authors: Magdalena
authors: M
authors: Komorowska
authors: João Paulo
authors: JP
authors: Teixeira
authors: Solange
authors: S
authors: Costa
authors: Laura-Ana
authors: LA
authors: Corcuera
authors: Adela
authors: A
authors: López de Cerain
authors: Blanca
authors: B
authors: Laffon
authors: Vanessa
authors: V
authors: Valdiglesias
authors: Peter
authors: P
authors: Møller
mesh_terms: D002138:Calibration; D020552:Comet Assay / Q000379:methods* / Q000592:standards*; D004249:DNA Damage; D043382:DNA-Formamidopyrimidine Glycosylase / Q000032:analysis; D023381:Endpoint Determination; D006801:Humans; D007753:Laboratories / Q000592:standards*; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000166:cytology; D016014:Linear Models
chemical_list: D043382:DNA-Formamidopyrimidine Glycosylase