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P Roca

Publications and source records attributed to P Roca.

41 records · Page 3Linked to original sources
PubMed1985

Enzymatic lactate-specific radioactivity determination in biological samples.

A method for the measurement of specific lactate radioactivity in biological samples is presented. It is based on the following steps: (a) enzymatic conversion of lactate to pyruvate, (b) pyruvate conversion to 2,4-dinitrophenylhydrazone, (c) concentration-separation of the latter in reusable Amberlite XAD-7 polymeric adsorbent columns, and finally (d) estimation of the radioactivity thus retained compared with that of enzymatically untreated aliquots of the same samples. Specificity was ensured by the use of lactate dehydrogenase as specific recognizing agent for lactic acid. No interference from glucose, lactate, or amino acids was observed. The method presented is simple and can be applied in routine multiple estimations of lactic acid radioactivity in conjunction with the enzymatic measurement of lactate in biological samples in tracer metabolic studies.

Animals↗
PubMed1984

An enzyme specific method for estimation of pyruvic acid radioactivity in biological samples.

A method for the estimation of pyruvate radioactivity in complex biological samples is presented. After perchloric acid deproteinization, the samples were divided in two aliquots. All pyruvate was removed from the first aliquot with lactate dehydrogenase and NADH; the other was left undisturbed. Then all hydrophilic components of the sample were removed through an Amberlite XAD-7 column. The samples were treated with dinitrophenylhydrazine to obtain the corresponding hydrazones, which were retained in an Amberlite XAD-7 column and then were eluted with acetone and their radioactivity counted. The difference between both aliquots corresponded to the pyruvate radioactivity in the sample. No contamination by lactate, glycerol, glucose or amino acids was observed. The mean recovery of 5 determinations of pyruvate radioactivity was 91.3% +/- 1.0.

Acrylic Resins↗
PubMed1983

A simplified method for the estimation of individual amino acid radioactivity in plasma samples.

A method is presented for the quantitative estimation of the individual amino acid radioactivity in biological samples. The material is deproteinized with cold acetone, and, after acetone evaporation, is passed through a column containing 1 g of Amberlite XAD-2, then eluted with 10% ethanol. The samples are derivatized with Sanger's reagent (alkaline 1-fluoro-2,4-dinitrobenzene) and passed again through the Amberlite XAD-2 column; the 10% ethanol eluate is now discarded and the DNP-amino acids eluted with acetone. Aliquots are used for TLC chromatography on Silicagel plates; the spots are identified, cut away and their radioactivity estimated. The actual recovery of radioactivity in the spots is about 86-92% of the initial radioactivity. No contamination with radioactive glucose, lactate, pyruvate or glycerol has been observed.

Amino Acids↗
PubMed1981

A method for the simultaneous determination of total carbohydrate and glycerol in biological samples with the anthrone reagent.

A method for quantitative estimation of glycerol and total carbohydrate in biological samples is described. The samples, deproteinized with cold acetone or trichloroacetic acid, were treated in the cold with 10 vols. of 0.75% (w/w) anthrone in 84% (w/w) sulphuric acid, and then heated 10 min at 100 degrees C. Absorbance at 590 nm was used for evaluation of total carbohydrate content in the sample. The absorbance at 510 nm was used for the combined carbohydrate and glycerol estimation. This latter observation leads to the determination of the glycerol content of the sample because the carbohydrate interference is known from the data obtained at 590 nm. Uses of this method to determine glycerol and carbohydrate content in lipids of chicken egg-yolk samples are presented.

Animals↗