PARP exercise calculated in the permeabilized mononuclear leukocyte blood cells of 13 mammalian species correlated with most lifespan of the species. Researchers in Denmark have also observed that centenarians show a high action of glutathione reductase in crimson blood cells. Due to the significant variety of these present in some burials, it is believed they had a rather large financial price, and could be applied for "day to working day" buys.