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Biomedical subjects

S Ferraris

Publications and source records attributed to S Ferraris.

7 recordsLinked to original sources
PubMed1991

Tetrahydrobiopterin loading test in hyperphenylalaninemia.

Some cases of primary hyperphenylalaninemia are not caused by the lack of phenylalanine hydroxylase, but by the lack of its cofactor tetrahydrobiopterin. These patients are not clinically responsive to a phenylalanine-restricted diet, but need specific substitution therapy. Thus, it became necessary to examine all newborns screened as positive with the Guthrie test for tetrahydrobiopterin deficiency. Methods based on urinary pterin or on specific enzyme activity measurements are limited in their availability, and the simplest method, based on the lowering of serum phenylalanine after loading with cofactor, was discouraged by the finding that some dihydropteridine reductase-deficient patients were unresponsive. The preliminary observation that this limitation could be overcome by increasing the dose of the administered cofactor prompted us to reevaluate the potential of the tetrahydrobiopterin loading test in hyperphenylalaninemia. Fifteen patients, eight with ultimate diagnosis of phenylketonuria, three with 6-pyruvoyl tetrahydropterin synthase-, and four with dihydropteridine reductase-deficiency, have been examined by administering synthetic tetrahydrobiopterin both orally, at doses of 7.5 and 20 mg/kg, and i.v., at a dose of 2 mg/kg. All the tetrahydrobiopterin-deficient patients, unlike those with phenylketonuria, responded to the oral dose of 20 mg/kg cofactor by lowering their serum phenylalanine concentration markedly below baseline to an extent easily detectable by Guthrie cards. This method allows for a simple screening method when enzyme or pterin studies are not available.

Administration, Oral↗
PubMed1990

Determination of the oximes 2-hydroxyiminomethyl-3-methyl-1-[2-(3-methyl- 3-nitrobutyloxymethyl)]imidazolium chloride and 1-[1-(3-butynyloxymethyl)]-2-hydroxyiminomethyl-3-methylimida zolium chloride in plasma by high-performance liquid chromatography.

An assay is presented for the extraction and quantitation of two oximes, 2-hydroxyimino-methyl-3-methyl-1-[2-(3-methyl-3-nitrobutyloxyme thyl)] imidazolium chloride (oxime A) and 1-[1-(3-butynyloxymethyl)]-2-hydroxyiminomethyl-3-methylimidazo lium chloride (oxime B), in human plasma and is demonstrated to be linear over two overlapping concentration ranges: 10-500 and 100-1000 ng/ml. The assay utilizes a liquid-liquid, ion-pair extraction and a normal-phase chromatographic separation on a silica column with ultraviolet detection at 270 nm. The method is sensitive, rapid and accurate. The limit of detection is 10 ng/ml (signal-to-noise ratio S/N greater than 10). The mean extraction recoveries of the oximes were greater than 86% at all concentration levels. The intra-assay variability was less than 3.3%, the inter-assay variability less than 7.2%. The compound is stable in plasma for 23 weeks when stored at -15 degrees C or -80 degrees C.

Chromatography, High Pressure Liquid↗
PubMed1989

[Amino acid profile in patients with orthotopic liver transplant].

Plasma amino acids profile is assumed to be a good index of whole body amino acids balance and in particular to give information on the actual control of the transplanted liver on protein metabolism. Variations in plasma amino acids profile were studied in 12 patients undergoing orthotopic liver transplantation. Total parenteral nutrition (TPN) was maintained at 26.05 +/- 1.53 kcal/kg and 0.117 +/- 0.01 gN/kg until the 7th postoperative day. Following this, an enteral nutrition (EN) was added as to maintain a mixed metabolic therapy at 30.28 +/- 2.76 kcal/kg and 0.198 +/- 0.01 gN/kg. Such a treatment completely satisfied the caloric needs, while nitrogen input was prudently kept low in accordance to the lack of data on the metabolic effectiveness of the transplanted liver. Amino acids profiles showed an early metabolic recovery of the new liver. Therefore nitrogen input could be higher and more adequate to nitrogen needs.

Adult↗