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Biomedical subjects

P Ballesteros

Publications and source records attributed to P Ballesteros.

29 records · Page 2Linked to original sources
PubMed1986

Pyruvate decarboxylating action of L-cycloserine. The significance of this in understanding its metabolic inhibitory action.

We present evidence which demonstrates that L-cycloserine, structural analog of L-alanine, which is known to be an effective aminotransferase inhibitor, is also a potent inhibitor of cellular pyruvate metabolism. This effect was found to be related to its almost instantaneous action in decreasing pyruvate concentrations in a dose-dependent manner. 1H nuclear magnetic resonance studies clearly demonstrate that the irreversible removal of pyruvate induced by L-cycloserine is caused by the decarboxylating action of the latter. Pyruvate disappearance induced by L-cycloserine can be stoichiometrically accounted for as acetate. The process does not involve any chemically detected transformation of L-cycloserine. These observations lead to two main considerations regarding the known action of L-cycloserine. First, its inhibitory effect on gluconeogenesis from lactate could be explained only on the basis of its ability to reduce pyruvate availability with no apparent need for transaminase inhibition. Second, its ability as a transaminase inhibitor should be reconsidered in view of its potent decarboxylating action on pyruvate and probably other oxoacids.

Animals↗
PubMed1983

Synthesis and transport applications of 3-aminobicyclo[3.2.1] octane-3-carboxylic acids.

The isomeric 3-aminobicyclo[3.2.1]octane-3-carboxylic acids were synthesized and compared with the widely used (1R,2S,4S)-2-aminobicyclo[2.2.1]heptane-2-carboxylic acid as to specificity to the Na+-independent membrane transport system L of the Ehrlich ascites tumor cell and of the rat hepatoma cell line HTC. The presence of an additional methylene group in the ring system leads to an optically symmetrical amino acid, with the advantages that the product is devoid of isomeric contamination. Hence, optical resolution is not necessary to secure a homogeneous test substrate for discrimination of amino acid transport systems. Through its inhibitory action on the cellular uptake of known system-specific amino acids, the bicyclo[3.2.1]octane amino acid proved more reactive than the bicycloheptane analogue with the Na+-independent amino acid transport system of the test cells and not perceptibly reactive with the accompanying Na+-dependent systems. Recent evidence of the presence of a second component of Na+-independent amino acid transport, beyond system L, increases the importance of securing a variety of possibly discriminatory model substrates.

Amino Acids↗
PubMed1983

Psychological evaluation of intensive care nurses.

To understand the possible psychological repercussions of working in an ICU, we report on 18 nurses in our unit, who took the Minnesota Multiphasic Personality Inventory (MMPI), the Rorschach test, and two prints from the Phillipson test. Each nurse took these tests during her 1st month of work and again at 12 months; 9 repeated the tests once more 24 months after entering the ICU. The results demonstrated the absence of clinical evidence in all cases. Findings of the Rorschach indicate that the larger part of the group use defense mechanisms to confront the numerous harmful stimuli and the high level of anxiety. In spite of this, the Phillipson test shows approximately one-half of them to manage depressive situations correctly and formulate solutions and mechanisms of reparation.

Adaptation, Psychological↗
PubMed1981

Effect of diphenylhydantoin, granatane-3-spiro-5'-hydantoin and leptazol on mouse brain glutamate dehydrogenase, urea and ammonia levels in brain.

The effect of diphenylhydantoin (DPH), granatane-3-spiro-5'-hydantoin and leptazol has been checked on both GDH activity and ammonia and urea levels in brain. Concentrations of 90 mg/kg of leptazol decreased, significantly, the ammonium and urea levels in brain with respect to normal control. DPH and G-3SH had no effect on these metabolites against normal control. The association of DPH and leptazol decreased both urea and ammonium levels in brain but the association of G-3SH and leptazol decreased, significantly, urea levels but not ammonium's. DPH, leptazol at 90 mg/kg concentration and the association of DPH or G-3SH with leptazol had no significant effect on GDH activity while G-3SH increased the enzyme activity when it was measured in the direction of glutamate degradation. DPH, G-3SH and both concentrations of leptazol decreased the GDH activity when it was checked in the direction of glutamate synthesis. The association of DPH and leptazol did not produce any effects, while the association of G-3SH-leptazol increased the enzyme activity. DPH and G-3SH and leptazol at 110 mg/kg concentration decreased the relation of GDH activity between the biosynthetic and degradative sense. The association of G-3SH-leptazol increased this relation while leptazol and its association with DPH did not affect it.

Ammonia↗