“…This occurred even in patients in whom the DFMO was clearly acting effec tively as an ODC inhibitor, as evidenced by the decline achieved in the cellular po lyamine levels during the pretreatment period. Administration of MGBG to animals promotes large increases in the putrescine levels of rat intestinal mucosa [30], mouse brain [14], ventral prostate [18], spleens of LI210 leukemia-bearing mice [11], and transplantable prostate cancer [7], How ever, in contrast to the present findings in humans, all of the animal studies, except that done with ventral prostate, found that MGBG promoted a decrease or no change in tissue spermidine levels and little change in spermine levels. Administration of MGBG to animals promotes an in crease in tissue activities of both ODC [7,9,12,14,18,30] and AMeDC [9,15,18,27,30] providing a potential explanation for the increased cellular polyamines noted in the present study.…”