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Development of a rapid and sensitive radioassay has permitted study of the conversion of tryptophan to 5-hydroxytryptophan in mammalian tissues. Of normal tissues examined, beef and rat pineal gland contained the highest activity. This is the first direct demonstration of tryptophan hydroxylase in this hydroxyindole-rich tissue. Rat and rabbit brainstem and(More)
alpha-Difluoromethylornithine (RMI 71,782), a specific irreversible inhibitor of the first step in polyamine biosynthesis, that is, the formation of putrescine from ornithine by ornithine decarboxylase, cures mice infected with a virulent, rodent-passaged strain of Trypanosoma brucei brucei. This parasite is closely related to the trypanosomes that cause(More)
alpha-Difluoromethylornithine (DFMO), an enzyme-activated, irreversible inhibitor of ornithine decarboxylase, blocks polyamine biosynthesis and has antitumor effects in animal tumor models as well as in athymic mice implanted with human small cell carcinoma. This study was designed to determine the maximally tolerated dose of oral DFMO administered every(More)
The urinary excretion of kallikrein, an enzyme which cleaves a vasodilator kinin from kininogen substrate, was examined in three types of hypertensive rats. Enzyme activity was measured by both esterase activity (isotopic assay) and bioassay with purified rat urinary kallikrein as a standard. Excretion of kallikrein was found to increase with age in(More)
The presence of dialyzable hydroxyproline-containing peptides in plasma (1) and urine (2-4) has been known for some t,ime. Although their exact significance is not clear, the levels of these peptides in the absence of collagen or gelatin in the diet are a reflection of endogenous collagen metabolism (l-5). In a previous publication (6) it was shown that, in(More)