A scheme for the interpretation of primary and secondary disturbances of plasma and urinary amino acid profiles. A possible way to an expert system

doi:10.1016/0009-8981(94)05992-9

Clinica Chimica Acta

Volume 235, Issue 1, 28 February 1995, Pages 1-10

https://doi.org/10.1016/0009-8981(94)05992-9 Get rights and content

Abstract

A general scheme for the interpretation of primary and secondary abnormalities of plasma and urine amino acid concentrations is described. The key steps of this scheme are: analytical assessment of the measurements, comparison of results obtained with the reference values expressed in absolute and/or relative concentrations and identification of abnormally increased ninhydrin-positive compounds. The interpretation of results takes account of the various abnormalities induced by drugs or diet. The origins of these abnormalities are ordered by their frequency. A part of the proposed scheme is now computerized as the first step in the development of an expert system.

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Se presenta una revision sobre el papel que la hiperhomocisteinemia tieneen el desarrollo de preeclampsia, aportando nuestra experiencia endiferentes aspectos bioquimicos y geneticos relacionados con el tema.
Las concentraciones de homocisteina plasmatica total (Hct) observadasen gestantes son inferiores a las de mujeres fertiles no gestantes:2.o trimestre (mediana, 5,3 μÊmol/l; rango, 3,1-10 μÊmol/l); 3.er trimestre(mediana, 6,3 μÊmol/l; rango, 3,2-13,0 μÊmol/l). Definimos hiperhomocisteinemia(Hct > P95) durante el embarazo toda concentracion > 7,7 μÊmol/l (2.o trimestre) y > 10,5 μÊmol/l (3.er trimestre).
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La velocimetria Doppler de arterias uterinas en el 2.o trimestre es unmetodo que puede ser util para identificar a gestantes con riesgo depreeclampsia. La adicion de la determinacion de Hct no mejora significativamentesu predictibilidad.
Los polimorfismos en los genes implicados en el metabolismo de lahomocisteina estudiados no pueden ser considerados como determinantesde la hiperhomocisteinemia observada en las gestantes conpreeclampsia.
A revision about the role of hyperhomocysteinemia in the developmentof preeclampsia is presented, which summarises our experiencein different biochemical and genetic points in relation to this possibleassociation.
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We found an association between hyperhomocysteinemia and preeclampsia:tHcy values were significantly higher in the preeclampticgroup than in uncomplicated pregnancies; the OR for preeclampsia inhyperhomocysteinemic patients was 7.7 (CI 95%, 1.7-34.8). The otheramino acid concentrations were also higher in preeclamptic women.The negative correlation observed between homocysteine andfolate in the control group, was not present in preeclamptic women.
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Homocysteine and other plasma amino acids in preeclampsia and in pregnancies without complications
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To evaluate a) the plasma amino acid changes observed in pregnant women (n = 124) and b) the homocysteine and other amino acid changes in preeclampsic patients (n = 18), and to determine c) whether these changes were also evident in nonpregnant women with a prior history of preeclampsia (n = 18).
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Effect of lysine infusion on urea cycle in lysinuric protein intolerance
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Poor intestinal absorption and excessive renal loss of dibasic amino acids result in low plasma concentrations in patients with lysinuric protein intolerance (LPI). Arginine and ornithine deficiency impair the function of the urea cycle and cause hyperammonemia after protein intake, while chronic lysine deficiency may cause growth failure and lead to reduced bone density in such patients. Since high lysine concentrations inhibit several enzymes of the urea cycle in the liver, lysine supplementation may induce hyperammonemia in LPI. We thus studied how LPI patients tolerate high plasma lysine by intravenous (IV) infusion of 3.3 mmol/kg lysine hydrochloride over 90 minutes in 6 adult patients and 4 healthy controls. The plasma lysine concentration (mean ± SD, range) peaked in the patients (9,114 ± 1,864, 7,156 to 12,044 μmol/L) and controls (10,185 ± 2,253, 7,714 to 13,122 μmol/L) at 90 minutes. Urinary lysine excretion peaked in the second 2-hour urine collection in the patients (4,582 ± 1,276, 3,018 to 6,315 μmol/m² body surface area per hour) and in the first 2-hour collection in the controls (5,373 ± 1,766, 3,551 to 7,286 μmol/m²/h). Two patients had mild nausea but no hyperammonemia and one patient had moderate hyperammonemia (peak, 112 μmol/L) at the end of the infusion. Orotic acid excretion increased in 2 subjects with a peak excretion rate of 33 and 251 μmol/m²/h in the third 2-hour collection after starting the load. All other subjects remained asymptomatic and showed no change in plasma ammonia or urinary orotic acid excretion. We thus conclude that an acute increase in plasma lysine caused minimal clinical or biochemical untoward effects in patients with LPI. Moderate increases in plasma lysine after low-dose oral supplementation with lysine or well-absorbed lysine derivatives are probably well tolerated in LPI.
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Research communicationA scheme for the interpretation of primary and secondary disturbances of plasma and urinary amino acid profiles. A possible way to an expert system

Abstract

Clin Chim Acta

J Chromatogr

A collaborative study on the determination of free amino acids in blood plasma

J Sci Food Agric

Proficiency testing for biochemical genetics laboratories: the first of 10 rounds of testing (letter)

Am J Hum Genet

Establishement of an external quality assessment scheme of amino acid analysis: results from assays of samples distributed during two years

Clin Chem

An intra- and interlaboratory quality control for assay of amino acids in biological fluids: fourteen years of the french experience

Clin Chem

Ion-exchange chromatography and clinical criteria in the screening of the amino acidopathies

Clin Chim Acta

Clinical approach to inherited metabolic diseases in the neonatal period: a 20-year survey

J Inherit Metab Dis

Amino acid analysis of physiological samples

Modifications des concentrations des acides amines plasmatiques et urinaires induites par des therapeutiques

Ann Biol Clin

Research communication
A scheme for the interpretation of primary and secondary disturbances of plasma and urinary amino acid profiles. A possible way to an expert system