While in the control and placebo groups NPL values remained relatively stable , in the two treatment groups such values decreased marginally , with the greatest effects observed in the 4.0 J/cm2 group ( e.g. , at 5 min , differences in NPL [ mean + / - SEM ] : control group , 0.02 + / -0.03 msec ; treatment group 2 , 4 J/cm2 , -0.07 + / -0.03 msec ) .
