Enhancement of @entity18878 -promoted XXXX formation by treatment with @entity864 or @entity18878 prior to initiation.

@entity3653 @entity19 @entity5 @entity1185 @entity1373 @entity18575 @entity106 @entity865 @entity3365 @entity18878 @entity864
The effects of promoter treatments prior to initiation on subsequent promotion by @entity18878 were examined in SENCAR @entity19 . Groups of @entity19 received two applications of various complete as well as first and second stage promoters given at various time intervals prior to initiation ranging from 3 days to 10 weeks. The @entity19 were then initiated with 2 micrograms of @entity3653 ( @entity106 ) followed 2 weeks later by twice-weekly treatments with 2 micrograms of @entity18878 . The @entity1185 response in @entity19 , receiving pretreatments with 2 micrograms of @entity864 ( @entity865 ) either 3 days, 1, 2, 3 or 5 weeks before initiation, was similar to that seen when @entity865 was given after initiation during stage I of promotion followed by stage II of promotion with @entity18878 (4-5 @entity1185 per @entity19 in all groups). Surprisingly, pretreatment with the stage II promoter, @entity18878 (2 micrograms), either 2 or 5 weeks prior to initiation, also gave @entity1185 responses similar to that induced with the standard two-stage promotion protocol (4.7 and 6.4 @entity1185 per @entity19 , respectively). The @entity1185 response was less than that in the standard two-stage promotion protocol when pretreatments with the stage I promoter @entity3365 (80 micrograms/ @entity19 ) were given either 2 or 5 weeks before initiation (2.6 and 2.3 @entity1185 per @entity19 , respectively). However, a repeat experiment (currently in progress) with a higher dose of @entity3365 (160 micrograms/ @entity19 ) given 2 weeks prior to initiation indicates that it is more effective than the 80 micrograms dose. When the time interval between pretreatment and initiation was increased to 10 weeks, the @entity1185 response with @entity865 and @entity3365 pretreatment was reduced to below two @entity1185 per @entity19 and with @entity18878 pretreatment to below three @entity1185 per @entity19 , indicating the effect was reversible. Histological changes in epidermis of @entity19 which received two applications of these compounds correlated with the @entity5 response. In this regard, treatment with two applications of @entity865 and @entity18878 resulted in an @entity1373 of similar magnitude (epidermal thickness of 53.5 +/- 1.5 and 50.0 +/- 1.1 microns, respectively). The @entity1373 produced by treatment with two applications of 80 micrograms @entity3365 (39.4 +/- 1.8 microns) was significantly less. The ability of pretreatments with @entity18575 (20 mg) and chrysarobin (50 micrograms) to affect the subsequent promoting activity of @entity18878 was also examined.(ABSTRACT TRUNCATED AT 400 WORDS)
