Abstract
Summary
1. The effects of 8-azaguanine, 8-azaxanthine, benzimidazole, and 1,4-dimethanesulfonyloxybutane on the Brown-Pearce tumor in vitro were investigated. 8-Azaguanine proved lethal in 0.0016 M concentration in 5 days and in 0.0008 M concentration in 10 days, and benzimidazole was lethal in 0.005 M concentration in 10 days. 8-Azaxanthine and 1,4-dimethanesulfonyloxybutane proved ineffective in all concentrations used. 2. The comparative effects of 8-azaguanine on the Brown-Pearce tumor, which does not exhibit azaguanine deaminase activity, and on the normal rabbit testis, which also lacks this deaminase, were studied; and in both instances complete inhibition was obtained in the same time and at the same concentration. Paper chromatography tests on the feeding fluids of these 2 tissues also showed them to have negligible deaminase activity. 3. No reason is yet known for the disagreement, in the case of this rabbit tumor, between the results in vivo and those in vitro as regards inhibition by benzimidazole and by 1,4-dimethanesulfonyloxybutane (Haddow's GT 41); for 8-azaguanine, however, the results are consistent in animal and tissue culture.
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