Data are presented as means 6 standard errors of the means (SEM). Differences between two groups were determined by Student's two-tailed unpaired t tests or paired t tests (when normalized DI were compared), using GraphPad Prism 5.03 software. Differences with values of P,0.05 were considered significant. *, P,0.05; **, P,0.01; ***, P,0.001.