title: Temporal variation of hydroxyl radical generation and 8-hydroxy-2'-deoxyguanosine formation by coarse and fine particulate matter.
abstract: OBJECTIVE
  To determine the induction of 8-hydroxy-2'-deoxyguanosine (8-OHdG) by fine (<2.5 microm) and coarse (10-2.5 microm) particulate matter (PM) sampled over time at one sampling location, and to relate the observed effects to the hydroxyl radical (*OH) generating activities and transition metal content of these samples, and to meteorological parameters.
  
  
  METHODS
  Weekly samples of coarse and fine PM were analysed for H(2)O(2) dependent *OH formation using electron spin resonance (ESR) and formation of 8-OHdG in calf thymus DNA using an immuno-dotblot assay. Immunocytochemistry was used to determine 8-OHdG formation in A549 human epithelial lung cells. To determine temporal effects, samples from six weeks in summer and six weeks in autumn/winter were compared using ESR and the dotblot assay. Concentrations of leachable V, Cr, Fe, Ni, and Cu were determined by inductively coupled plasma mass spectrometry.
  
  
  RESULTS
  Both PM fractions elicited *OH generation as well as 8-OHdG formation in calf thymus DNA and in A549 cells. 8-OHdG formation in the naked DNA was significantly related to *OH generation, but not to metal concentrations except for copper. A significantly higher *OH generation was observed for coarse PM, but not fine PM collected during the autumn/winter season; this was not due to differences in sampled mass or metal content. Specific weather conditions under which increased *OH formation in the coarse mode was observed suggest that other, as yet unknown, anthropogenic components might affect the radical generating capacity of PM.
  
  
  CONCLUSIONS
  Both coarse and fine PM are able to generate *OH, and induce formation of 8-OHdG. When considered at equal mass, *OH formation shows considerable variability with regard to the fraction of PM, as well as the sampling season. The toxicological implications of this heterogeneity in *OH formation by PM, as can be easily determined by ESR, need further investigation.
authors.affiliation: Institut für umweltmedizinische Forschung (IUF) an der Heinrich-Heine-Universität Düsseldorf gGmbH, Auf'm Hennekamp 50, D-40225 Düsseldorf, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Shi
authors.forename: A M
authors.initials: AM
authors.lastname: Knaapen
authors.forename: J
authors.initials: J
authors.lastname: Begerow
authors.forename: W
authors.initials: W
authors.lastname: Birmili
authors.forename: P J A
authors.initials: PJ
authors.lastname: Borm
authors.forename: R P F
authors.initials: RP
authors.lastname: Schins
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000378:metabolism; D003839:Deoxyadenosines / Q000378:metabolism*; D004306:Dose-Response Relationship, Immunologic; D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000737:chemistry* / Q000378:metabolism; D008685:Meteorological Concepts; D010316:Particle Size; D013950:Thymus Gland / Q000378:metabolism
chemical_list: C436623:8-hydroxy-2'-deoxyadenosine; D003839:Deoxyadenosines; D017665:Hydroxyl Radical; D004247:DNA