Age, sex, and race influence single-strand break repair capacity in a human population.
Recently, we developed an improved comet assay protocol for evaluating single-strand break repair capacity (SSB-RC) in unstimulated cryopreserved human peripheral blood mononuclear cells (PBMCs). This methodology facilitates control of interexperimental variability [A.R. Trzeciak, J. Barnes, M.K. Evans, A modified alkaline comet assay for measuring DNA repair capacity in human populations. Radiat. Res. 169 (2008) 110-121]. The fast component of SSB repair (F-SSB-RC) was assessed using a novel parameter, the initial rate of DNA repair, and the widely used half-time of DNA repair. The slow component of SSB repair (S-SSB-RC) was estimated using the residual DNA damage after 60 min. We have examined repair of gamma-radiation-induced DNA damage in PBMCs from four age-matched groups of male and female whites and African-Americans between ages 30 and 64. There is an increase in F-SSB-RC with age in white females (P<0.01) and nonsignificant decrease in F-SSB-RC in African-American females (P=0.061). F-SSB-RC is lower in white females than in white males (P<0.01). There is a decrease in F-SSB-RC with age in African-American females as compared to white females (P<0.002) and African-American males (nonsignificant, P=0.059). Age, sex, and race had a similar effect on intercellular variability of DNA damage in gamma-irradiated and repairing PBMCs. Our findings suggest that age, sex, and race influence SSB-RC as measured by the alkaline comet assay. SSB-RC may be a useful clinical biomarker.
Laboratory of Cellular and Molecular Biology, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
Andrzej R
AR
Trzeciak
Janice
J
Barnes
Ngozi
N
Ejiogu
Kamala
K
Foster
Larry J
LJ
Brant
Alan B
AB
Zonderman
Michele K
MK
Evans
D000328:Adult; D001741:Black or African American; D000367:Age Factors; D020552:Comet Assay / Q000379:methods; D004249:DNA Damage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000032:analysis* / Q000235:genetics*; D005260:Female; D005720:Gamma Rays; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D044469:Racial Groups / Q000235:genetics*; D012737:Sex Factors; D044465:White People
D004277:DNA, Single-Stranded