title: Inter-individual and inter-cell type variation in residual DNA damage after in vivo irradiation of human skin.
abstract: OBJECTIVE
  The aim of this study was to compare inter-individual and inter-cell type variation in DNA double-strand break (DSB) repair following in vivo irradiation of human skin.
  
  
  METHODS
  Duplicate 4mm core biopsies of irradiated and unirradiated skin were collected from 35 patients 24h after 4Gy exposure using 6MeV electrons. Residual DSB were quantified by scoring 53BP1 foci in dermal fibroblasts, endothelial cells, superficial keratinocytes and basal epidermal cells.
  
  
  RESULTS
  Coefficients of inter-individual variation for levels of residual foci 24h after in vivo irradiation of skin were 39.9% in dermal fibroblasts, 44.3% in endothelial cells, 32.9% in superficial keratinocytes and 46.4% in basal epidermal cells (p<0.001, ANOVA). In contrast, the coefficient of inter-cell type variation for residual foci levels was only 11.3% in human skin between the different epidermal and dermal cells (p=0.034, ANOVA). Foci levels between the different skin cell types were correlated (Pearson's R=0.855-0.955, p<0.001).
  
  
  CONCLUSIONS
  Patient-specific factors appear to be more important than cell type-specific factors in determining residual foci levels following in vivo irradiation of human skin.
authors.affiliation: Health Protection Agency, Chilton, UK. drmelvinchua@gmail.com
authors.forename: Melvin Lee Kiang
authors.initials: ML
authors.lastname: Chua
authors.forename: Navita
authors.initials: N
authors.lastname: Somaiah
authors.forename: Sara
authors.initials: S
authors.lastname: Bourne
authors.forename: Frances
authors.initials: F
authors.lastname: Daley
authors.forename: Roger
authors.initials: R
authors.lastname: A'hern
authors.forename: Otilia
authors.initials: O
authors.lastname: Nuta
authors.forename: Sue
authors.initials: S
authors.lastname: Davies
authors.forename: Carsten
authors.initials: C
authors.lastname: Herskind
authors.forename: Ann
authors.initials: A
authors.lastname: Pearson
authors.forename: Jim
authors.initials: J
authors.lastname: Warrington
authors.forename: Sarah
authors.initials: S
authors.lastname: Helyer
authors.forename: Roger
authors.initials: R
authors.lastname: Owen
authors.forename: John
authors.initials: J
authors.lastname: Yarnold
authors.forename: Kai
authors.initials: K
authors.lastname: Rothkamm
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001706:Biopsy; D001943:Breast Neoplasms / Q000532:radiotherapy*; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D042783:Endothelial Cells / Q000528:radiation effects*; D005260:Female; D005347:Fibroblasts / Q000528:radiation effects*; D006801:Humans; D007124:Immunoenzyme Techniques; D015603:Keratinocytes / Q000528:radiation effects*; D011832:Radiation Injuries / Q000235:genetics*; D012867:Skin / Q000166:cytology* / Q000528:radiation effects*