I think he still holds World record as human who can wihstand the highest power frequency voltage hand-to-hand(don't know exactly how much it is but it is order of several thousand volts).At least Guinnes book of records says so.In USA he wanted to try an electric chair some 20 years ago but they didn't let him!
Scientists did some tests on him.All they could find was that he doesn't sweat at all (makes extremely high skin resistance) and when he conducts small currents his tissues behave like condensers.Curious thing that electronic devices tend to mailfunction in his vicinity.Anyway,he is a medical phenomenon.