Enikson Pontes da Silva

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A sensitive and simple method was developed for the quantitation of levodopa and its metabolite 3-O-methyldopa, in human plasma, after oral administration of tablet formulations containing levodopa (200 mg) and benserazide (50 mg). The analytes were extracted by a protein precipitation procedure, using carbidopa as an internal standard. A mobile phase(More)
A rapid method for the quantification of glucosamine in human plasma using high-performance liquid chromatography coupled to tandem mass spectrometry was developed and validated. The sample preparation includes a simple deproteinization step, using D-[1-¹³C] glucosamine hydrochloride as an internal standard. Chromatographic separation was performed on an(More)
A new method was developed for the quantitation of 3-α-hydroxy tibolone, in human plasma, after oral administration of a tablet formulation containing tibolone (2.5 mg). 3-α-Hydroxy tibolone was extracted by a liquid-liquid procedure, using cyproterone acetate as internal standard and chlorobutane as extraction solvent. After extraction, samples were(More)
Poultry maintenance requirements for valine, isoleucine, and tryptophan were measured by nitrogen balance using different unit systems. The nitrogen balance trial lasted 5 d with 48 h of fasting (with roosters receiving only water+sucrose) and the last 72 h for feeding and excreta collection. Forty grams of each diet first-limiting in valine, isoleucine, or(More)
AIM The aim of this study was to evaluate the effects of N-acetylcysteine or L-arginine in the antioxidant system of skeletal muscle cells in culture. METHODS We used C2C12 cells which were supplemented or not with N-acetylcysteine or L-arginine at different time points. Antioxidant enzymes' activities and protein expression were evaluated. Additionally,(More)
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