Self-administering emergency hormonal contraception.
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Adolescent↗
Biomedical subjects
J P McMullen
Publications and source records attributed to J P McMullen.
Interactions of chlorphenesin and divalent metal ions with phosphodiesterase.
Chlorphenesin inhibition of the hydrolysis of cyclic AMP by guinea-pig lung phosphodiesterase was reversed by the addition of exogenous magnesium ions. Chlorphenesin and theophylline inhibition of this enzyme was shown to be noncompetitive when the substrate concentration was low. Kinetic studies of the inhibition of beef heart phosphodiesterase by chlorphenesin and theophylline indicated that the substrate concentration was a factor in determining whether inhibition was competitive or noncompetitive. Calcium, cobalt and copper ions were inhibitory to guinea-pig lung phosphodiesterase. The inhibition due to chlorphenesin was partially reversed by low (40 mM or less) concentrations of barium ions; high concentrations of barium ions, or manganese ions, were inhibitory. The concentration of the divalent cation did not affect the type of inhibition that was observed.
3',5'-Cyclic-AMP Phosphodiesterases↗
Hexachlorophene metabolism in rats: the hepatic route.
The terminal elimination rate of radioactivity from the bile of bile-duct cannulated rats, that had received hexachlorophene-14C via the hepatic portal vein, had an apparent first-order half-life of about 10 hr. Tissue distribution studies in these rats indicated that 35-47% of the carbon-14 of the dose was eliminated through the bile within 24 hr. Significant amounts of radioactivity were also found in the liver and carcass at that time; the brain was the only tissue that did not consistently have much higher concentrations of carbon-14 than the blood. The rate limiting step in the disposition of hexachlorophene may be excretion into the bile. A bile-feeding technique demonstrated enterohepatic circulation.
Animals↗
O-Demethylation of p-nitroanisole by Escherichia coli. Stimulation by phenobarbital.
Intact cells of the bacterium Escherichia coli ATCC 11229, can convert p-nitroanisole into p-nitrophenol. The presence of phenobarbital in the culture medium during growth of the cells results in an inhibition of bacterial cell mass and an increased ability of the bacterial cell to carry out the O-demethylation reaction. There was a linear relationship between the amount of product formed and the bacterial cell mass in the incubation mixture. Varying the substrate concentration gave a concomitant change in activity, defined as the amount of product formed per mg of bacterial cell mass per 150 min. The optimum temperature for the production of p-nitrophenol by the stimulated cells was 33 degrees C; 7.0 was the pH optimum.
Escherichia coli↗