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Biomedical subjects

V R Villanueva

Publications and source records attributed to V R Villanueva.

11 recordsLinked to original sources

Chromatography, flow injection analysis and electrophoresis in computer-assisted comparative biochemistry: its application and possibilities in clinical research. Preliminary studies on Crohn's disease.

A computer-assisted multicomponent analytical system, developed for comparative biochemical studies, was used for a clinical study of Crohn's disease in which 73 subjects, of comparable age and sex distribution, were considered: 40 with Crohn's disease, 16 with ulcerative colitis and 17 healthy volunteers as controls. Blood samples (5 ml) were taken to recover plasma and red cells. After extraction and fractionation of low- and high-molecular weight substances, the samples were analysed by ion-exchange chromatography and electrophoresis. The contents of amino acids, sugars, polyamines and proteins in the plasma and the red cells from the three groups of individuals were compared using statistical (means, variance, principal components analysis) and graphical profile methods. The first results indicate that the content of red cells, in comparison with plasma, allows the best differentiation of the three groups of subjects considered. In particular, the amino acids (Asp, Thr, Ser, Glu, Gly, Ala and Leu), the polyamines (spermidine and spermine) and glucose, show the most significant differences. The methodology followed and the results obtained, together with possible uses of this computer-assisted multicomponent analytical system in problems concerning clinical research, are discussed.

Adult

On the presence of carnitine acetyl transferase in human platelets.

The presence of carnitine acetyl transferase (E.C.2.3.1.7) activity has been found for the first time in human platelets. The enzymic activity was measured by a radiometric method based on the separation of labelled acetylcarnitine and carnitine on a cation exchange column. Carnitine acetyl transferase activity closely paralleled the activity distribution of the mitochondrial marker carnitine palmitoyl-transferase. Contrary to the marker enzyme, human platelet carnitine acetyl-transferase is rather thermosensitive: 60% of its activity is lost after 10 min when kept at 37 degree C.

Acetyltransferases

Human platelet arginase.

We report here, for the first time the presence of arginase in human platelets. This enzyme has been partially purified and some of it properties studied. Its biological significance and its involvement in polyamine biosynthesis are considered.

Arginase

Purification and characterization of epsilon-N-trimethyllysine L-amino oxidase from Neurospora crassa.

epsilon-N-Trimethyllysine L-amino oxidase from Neurospora crassa has been purified to electrophoretic homogeneity. A 1500-fold purification was obtained by centrifugation and successive column chromatography on ion-exchange and gel filtration supports. The enzyme has an estimated molecular weight of 160 000. It transforms epsilon-N-trimethyllysine into alpha-keto, epsilon-N-trimethylhexanoic acid by oxidative deamination. Kinetic studies of this new enzyme are reported and its probable physiological role is discussed.

Amino Acid Oxidoreductases

Automated analysis of common basic amino acids, mono-, di-, and polyamines, phenolicamines, and indoleamines in crude biological samples.

A fully automated, fast, and sensitive method for the separation of common basic amino acids and mono-, di-, and polyamines as well as phenolic- and indoleamines is described. Picomole level determination of hydroxytryptophan, tryptophan, histidine, lysine, ethanol amine, arginine, noradrenaline, diaminopropane, putrescine, histamine, cadaverine, dopamine, hexamethylenediamine, agmatine, tyramine, phenethylamine, serotonin, 5,6-dihydroxytryptamine, 5-methoxytryptamine, tryptamine, spermidine, and spermine is carried out by ion-exchange column chromatography on a single sample in 170 min of total analysis. This method is well suited for crude extracts without preliminary purification, thus reducing preparative losses. The reproducibility of the method has been studied and the percentage recovery of the different compounds after column chromatography is reported. Its application to crude samples from different biological sources such as microorganisms, vegetables, platelets, and urine is presented. This method could serve as a powerful tool for the analysis of these amino compounds in which there is currently a considerable interest.

Adult

[Isolation of a new keto-acid, produced from epsilon-N-trimethyllysine by Neurospora crassa].

A new epsilon-N-trimethyllysine metabolite has been isolated from the mycelium of Neurospora crassa. The labelled compound produced from incubations in vivo and in vitro from epsilon-N-trimethyl ([14-C]H3)L-lysine has been identified as 2-keto-epsilon-N-trimethyl-hexanoic acid by reducing its 2,4-dinitrophenyl hydrazone back to epsilon-N-trimethyllysine by hydrogenolysis in a Parr bomb. Analyses on TLC and in four different ion exchange chromatographic systems show the appearance of a ninhydrin positive product having the same Rf and the same retention time as epsilon-N-trimethyllysine; it contains more than 85% of the radioactivity of the 2,4-dinitrophenylhydrazone of the keto acid.

Chromatography, Ion Exchange