Table 1.

Sensitivity of PBLs to oxidative stress challenge, but not endogenous DNA damage in PBLs, is associated with high prostatic DNA damage in elderly beagle dogs

Endogenous DNA damage in PBLsRange of extensive DNA damage (%)Univariate OR (95% CI)Multivariate* OR (95% CI)
First tertile (n = 28)5-121.0 (reference)1.0 (reference)
Second tertile (n = 20)13-180.6 (0.16 to 2.1)No selection
Third tertile (n = 17)19-281.1 (0.33 to 3.8)No selection
Oxidative stress-induced DNA damage in PBLs
Range of extensive DNA damage (%)
Univariate OR (95% CI)
Multivariate* OR (95% CI)
First tertile (n = 23)15-301.0 (reference)1.0 (reference)
Second tertile (n = 20)31-394.9 (1.1 to 22.1)6.6 (1.3 to 32.2)
Third tertile (n = 22)40-975.6 (1.3 to 24.3)7.6 (1.5 to 38.2)
  • NOTE: Endogenous DNA damage measured by alkaline Comet assay was quantified by the percentage of cells with extensive DNA damage (visually scored as type 3 or type 4 damage). Oxidative stress-induced PBL damage is expressed as the H2O2-inducible DNA damage index, which is calculated as follows: (damage after H2O2 challenge − endogenous damage)/(100 − endogenous damage). The end point of the study, high prostatic DNA damage, was defined as the highest tertile of prostatic DNA damage found in the prostates of the 65 dogs in the study population for which complete data were available. Mean prostatic DNA damage in elderly beagle dogs was 67%, with a range of 40% to 97%. Ranges for tertiles of prostatic DNA damage were as follows: lowest (40-54%), middle (55-77%), and highest (78-97%) tertiles of prostatic DNA damage.

  • * Multivariate OR adjusted for toenail selenium concentration, age, change in body weight, and serum testosterone.

  • Not selected as a significant predictor of high prostatic DNA damage in stepwise multivariate logistic regression.