John G. Olenick

Leishmania braziliensis panamensis: Increased infectivity resulting from heat shock

Promastigotes of Leishmania braziliensis panamensis were subjected to a heat shock transformation yielding an amastigote-like stage. During the process of conversion, the heat-induced differentiating form displayed an increase in infectivity (as determined by lesion size) accompanied by a total protein composition unlike that of the promastigote and a morphology resembling that of the amastigote. These biological/functional changes may be related to an involvement of a heat shock response in the differentiation of leishmania, thus having important implications in the development of prevention and treatment stratagems.

Mode of action of primaquine: preferential inhibition of protein biosynthesis in Bacillus megaterium.

The growth of a strain of Bacillus megaterium was prevented by a minimal inhibitory concentration of primaquine of 52 μg/ml or 2 × 10−4m. When exponentially growing cultures received the drug at 6 × 10−4m, the rate of growth was drastically reduced and no further growth occurred after 15 min of exposure. At this concentration, primaquine was bactericidal, causing a 50% reduction in the viable population after one doubling time of 45 min. Supplying primaquine to cultures 30 min after adding radioactive-labeled phenylalanine, thymidine, uracil, or diaminopimelic acid produced an immediate and complete inhibition of protein biosynthesis but no inhibition of deoxyribonucleic acid biosynthesis for at least 15 min, and caused the formation of ribonucleic acid and cell wall polymer to proceed linearly at rates similar to those established prior to the addition of drug. This pattern of inhibition of macromolecular biosyntheses suggests that the major in vivo action of primaquine in B. megaterium is to block protein synthesis.

A 50 s ribosomal determinant: Immunological studies correlating function and structure

Ribosomes sedimented to equilibrium in cesium chloride are partially stripped of proteins and result in particles having sedimentation coefficients of 40 s and 23 s. Preparations of 50 s ribosomal subunits from Escherichia coli were banded in cesium chloride, and the split proteins were used to obtain specific antiserum. This antiserum reacted with 50 s subunits and 70 s ribosomes; core (40 and 23 s) particles and 30 S subunits were non-reactive. Only 50 s ribosomal subunits isolated from bacteria taxonomically related to E. coli displayed similar immunological reactivity. Immunoelectrophoretic analyses demonstrated one precipitin band, suggesting that the antiserum was specific for a 50 s split protein determinant. Ribosomes pre-incubated with sRNA exhibited a significant reduction in serological reactivity. Soluble RNA preparations were oxidized by periodate and were exposed to cyclohexylamine, a treatment known to remove the terminal nucleoside and to result in a drastic reduction of sRNA binding to ribosomes. When such an sRNA preparation was used in the pre-incubation, no protection was afforded, and the ribosomes showed the usual serological reactivity. These results indicate that the 50 s split protein determinant studied was located near, or was perhaps identical to, the sRNA binding site.

Antibacterial Action of Primaquine: Effects In Vitro on Polypeptide Synthesis and In Vivo on Ribosomes and Ribosomal Ribonucleic Acid

Primaquine inhibited polyphenylalanine formation directed by poly(U) in a cell-free system obtained from Bacillus megaterium only when the drug was preincubated with transfer ribonucleic acid (tRNA), poly(U), or ribosomes. Considerably less inhibition was produced when the ionic strength of the preincubation mixture of tRNA or poly(U) plus primaquine was increased; with ribosomes, the extent of inhibition was only slightly reduced. In cultures of B. megaterium, primaquine induced the breakdown of ribosomes and their RNA.

Peptide Mapping of Variant Glycoproteins from Trypanosoma Rhodesiense by Reverse Phase Liquid Chromatography

Abstract Peptides of trypsin-digested surface coat glycoproteins isolated and purified from 4 cloned variants of Trypanosoma rhodesiense (Wellcome strain) were mapped by reverse phase high performance liquid chromatography. The peptide maps provide definitive chemical data demonstrating a lack of structural homology among the variant glycoproteins.

Bacteriological Studies with Morphine-Like Narcotics: Relevance to Narcotic Actions in Mammals?

A search for active bacterial growth inhibitors among seven highly potent morphine-like narcotics revealed that NIH 7591 and etorphine inhibited the rates of growth of Escherichia coli by 50% at 1.9 × 10−4 M. Bacterial cultures escaped from growth inhibition by NIH 7591 after times which were proportional to the drug concentrations and inversely proportional to the initial bacterial densities. Populations of E. coli could adapt to resist and cross-resist growth inhibitions by NIH 7591 and phenazocine. Resistance was lost after growth in drug-free medium for a few doubling times. The agonist-antagonist pair, etorphine and diprenorphine, inhibited growth of E. coli additively without any indication of antagonism. Actions of narcotics in bacteria is considered a theme in its own right.