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Biomedical subjects

E I Szabo

Publications and source records attributed to E I Szabo.

7 recordsLinked to original sources
PubMed1987

Control of low Km cyclic adenosine 3',5'-monophosphate-phosphodiesterase in prostate and heart of adult and aged rats.

The activity of low Km cAMP-phosphodiesterase (PDE) was determined in extracts of prostate and heart of adult (10-12 months old) and aged (32-35 months old) Sprague-Dawley rats; the enzyme's response to endogenous inhibitors extracted from the two organs was analyzed by kinetic studies. Different mechanisms of inhibition, non-competitive in prostate and competitive in heart extracts, indicate organ-specificity of the inhibitor. The decreased PDE activity in organ extracts of aged rats and its continued sensitivity to the endogenous inhibitor suggest an age-associated impairment of the tissues' ability to terminate cAMP-mediated signals.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1986

Endogenous inhibitors of cyclic adenosine 3',5'-monophosphate-phosphodiesterase in rat epididymis.

Stabilization of cyclic adenosine 3',5'-monophosphate (cAMP)-phosphodiesterase (PDE) in 50% glycerol made possible the removal of endogenous inhibitors from tissue extracts by dialysis and the storage of the extracts at -20 degrees C without loss of PDE activity. Dialysates of heat-inactivated epididymal extracts were fractionated by liquid chromatography, and 4 fractions-F2, F5, F7, and F12-were found to contain endogenous inhibitors of PDE. The masses of the fractions required to inhibit low-Km PDE activity by ca. 50% in 430-microliter incubation mixtures were F2, 89 micrograms; F5, 23 micrograms; F7, 275 micrograms; and F12, 1.2 mg. The mechanisms of inhibition of low-Km PDE by the endogenous inhibitors were investigated by kinetic analysis of enzyme-inhibitor interaction. F2 and F12 inhibited PDE competitively; F5 and F7 decreased both apparent Km and Vmax, suggesting an uncompetitive mechanism of inhibition. The high potency of F5 in low concentration suggests that it may be a physiological modulator of low-Km cAMP-PDE activity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Presence of squalene in gram-positive bacteria.

The presence of the isoprenoid squalene, synthesized de novo, was demonstrated in 64 out of 73 strains of gram-positive bacteria by thin-layer chromatography. This observation was confirmed by gas-liquid chromatography, chemical reactivity, incorporation of radiolabeled precursor, and by gas chromatography mass spectroscopy of thin-layer chromatography-recovered material.

Bacteria↗