-The effects of various cytotoxic chemicals, as measured by viable cell counts, colony-forming ability and proliferative capacity, have been studied using Chinese hamster cells in exponential and plateau (stationary) phases of growth. The proliferating cells were altogether more sensitive to the action of the drugs than nonproliferating cells. However, imuran (azathioprine) a purine antimetabol...

A simple bacteriological technique involving inhibition zone production on a lawn of Escherichia coli was developed to detect antimetabolite toxin production by phytopathogenic species of Pseudomonas. It was established that the mechanism of E. coli inhibition paralleled that of phytotoxin-induced chlorosis of plant tissue. Derivatives of Pseudomonas tabaci and Pseudomonas phaseolicola which di...

INTRODUCTION Mitomycin C is gaining widespread popularity as an adjunctive with trabeculectomy, as it significantly increases the success rate of the procedure. But it is associated with serious sight-threatening complications. MATERIALS AND METHODS Twenty eyes planned for trabeculectomy from the glaucoma clinic were enrolled for the study after obtaining an informed consent. The baseline imp...

The molecular formula of a new antimetabolite produced by Streptomyces purpurascens was determined to be C5H5N5O2 by elemental analysis, FD-MS and 13C NMR. Reduction of this antimetabolite with Raney nickel yielded guanine. The antimetabolite was distinguishable from known N-hydroxyguanines by comparison of their UV spectra. The structure of the antimetabolite was finally established to be 7-hy...

Memory of a shock-avoidance task in goldfish (Carassius auratus) maintained at 20°C shows a temporal gradient of insusceptibility to post-trial injection of puromycin upon testing 7 days later. Treatment with the antimetabolite 24 hr after training has no effect on retention. There is a significant decrease in the puromycin-induced memory loss if fish are warmed to 30°C for a 90-minute interval...

The roles of anthranilate and histidine in the regulation of tryptophan synthesis were implicated by observations of antagonistic relationships with 5-methyltryptophan in Bacillus subtilis.

Present knowledge of the metabolic role of thioctic acid (lipoic acid) is derived almost exclusively from studies of bacterial enzyme systems, although it may well have similar functions in higher plants and animals. A number of microorganisms are known which have an absolute growth requirement for thioctic acid but higher animals do not seem to require preformed thioctic acid for growth. If ef...