Potentiating and inhibiting effects of steroid hormones on the incidence of 90Sr induced XXXX .

@entity2931 @entity19 @entity5 @entity421 @entity617
Eight hundred and twenty male CBA- @entity19 , 75 +/- 3 days of age were divided into four main series. Three of these; A, B and C were further divided into three subgroups. To these 90Sr was given at three different dose levels alone (A) or in combination with either @entity2931 (B) or @entity617 (C). In one series (D) all animals were given only @entity2931 . The development of intramedullary @entity2931 induced bone formation and the early events of @entity5 induction are reported. The 90Sr activities were selected in such a way that the lowest one would be below, the intermediate beyond and the highest well above the limit of @entity5 induction. Comparing the 90Sr injected animals with those given also @entity2931 revealed that @entity2931 had no promoting effect at the lowest and intermediate dose levels but increased the @entity5 incidence with a factor 4 at the highest dose level whereas @entity617 had an inhibitory effect. From the results obtained it was proposed that @entity2931 may act only as a preparatory promoter and not assist in the initiating events. As has been reported elsewhere, the frequency of osteoblastic and @entity421 was higher in animals given @entity2931 and 90Sr than 90Sr only. @entity19 given only @entity2931 did not develop @entity5 .
