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Biomedical subjects

J M Barba

Publications and source records attributed to J M Barba.

2 recordsLinked to original sources

[Intraventricular meningiomas].

Eight cases of surgically intervened intraventricular meningiomas are presented. The patients were six males and 2 females with a mean age of 41.7 years (11-70). The length of symptoms was of several months in 6 (75%) of the cases. The most frequent symptoms observed were cephalea and alterations of the upper functions which were presented in six and four cases, respectively. Papilloedema and involvement of long pathways were the most usual findings observed in neurological examination. Diagnosis was made by computerized tomography and angiography in all the cases. Surgery using a transtemporal approach was carried out in six patients and in the other two a parietal-occipital route was used. Two patients were dead and other two presented bilateral amaurosis. The other patients had good postsurgery.

Adolescent↗

Dissociation of aspartate aminotransferase into subunits. Effect of ligands upon this dissociation.

Frontal and zonal analysis of the chromatography of aspartate aminotransferase (EC2.61.1), pig heart cytosolic enzyme, on Bio-Gel P150 shows that holo- and apoenzyme can dissociate at pH 8.3. Ultracentrifugation and fluorescence depolarization confirm this result. Kinetic analysis of the fluorescence depolarization experiments favors a biphasic phenomenon: a few minutes for the faster one and several hours for the slower one. The apparent dissociation constant is 0.8 muM for the apoenzyme and 0.18 muM for the pyridoxal 5'-phosphate form of the holoenzyme. In the presence of sucrose or 0.1 M L-aspartate or a mixture of 70 mM L-glutamate and 2 mM alpha-ketoglutarate, the holoenzyme is dimeric at concentrations higher than 5 nM. The addition of a mixture of the substrates L-glutamate and alpha-ketoglutarate to a monomeric holoenzyme leads to dimerization. The stability of the dimeric form is in the order: holoenzyme + substrates greater than apoenzyme.

Aspartate Aminotransferases↗