Organic acids, Amniotic fluid

Kumps A, Vamos E, Mardens Y, Abramowicz M, Genin J, Duez P (2004) Assessment of an electron-impact GC-MS method for organic acids and glycine conjugates in amniotic fluid. J Inherit Metab Dis 27 567-579... 

Holocarboxylase synthetase deficiency can be diagnosed prenatally by assessing the response of carboxylase activity in cultured amniocytes (obtained by amniocentesis) to the addition of biotin, or by the detection of methylcitric and hydroxyisovaleric acids in the amniotic fluid. Prenatal therapy, by giving the mother 10 mg of biotin per day, results in sufficiently elevated fetal blood concentrations of biotin to prevent the development of organic acidemia at birth. 

Organic acids have also been studied in plasma, e.g. [341], amniotic fluid [363] and CSF [364]. Several other classes of compounds have received attention in profile analysis, most notably steroids (see above under Steroids) and amino acids [340,341]. 

The formation of cyclic isoxazolinones on reaction of organic acids with hydroxylamine hydrochloride [13] is utilized for the derivatization of succinylacetone (2,4-dioxoheptanoic acid). After stabilization of the keto groups by isoxazole formation in this way, the remaining carboxylic acid group is esterified with pentafluoro-benzyl bromide for GC—MS assay in El [193] or NlCl [194] mode. The latter mode is required to measure the low levels present in amniotic fluid. 

Gas Chromatography-Mass Spectrometric Analysis of Organic Acids and Amino Acids in Amniotic Fluid Koenshu - lyo Masu Kenkyukai 3 137-142 (1978) GA 92 193773k... 

Adsorption of Organic Acids from Amniotic Fluid and Urine Onto Silica Glass Before Analysis by Gas Chromatography and Combined Gas Chromatography/Mass Spectrometry... 

Amniotic fluid has limited value in prenatal diagnosis for the aminoacid-opathies. Unlike the organic acid disorders, in most amino acid disorders the metabolites do not accumulate before birth. Abnormal amino acid patterns in amniotic fluid have only been found in two of the urea cycle disorders, namely argininosuccinate lyase deficiency (argininosuccinic acidemia) and argininosuccinate synthetase deficiency (citrullinemia). 

The second part of the book is concerned with the organic acids in physiological fluids from normal subjects and presents both qualitative and quantitative data on adults and on the normal infant and normal neonate. The prenatal diagnosis of organic aciduria by direct chemical analysis of amniotic fluid has been achieved and the potential of this technique is underlined by a section on the organic acids normally present in this fluid. 

Amniotic fluid is of interest because of the possibility of prenatal diagnosis of metabolic diseases by direct chemical analysis (as well as enzyme activity measurements as cultured cells) and this is discussed in detail in Section 9.3. The nature of the fluid and normal data for organic acids are discussed in Section 8.1. 

Hagenfeldt, L. and Hagenfeldt, K. (1972), Gas chromatographic-mass spectrometric analysis of organic acids in amniotic fluid. Clin. Chim. Acta, 42,219. 

Some data on specific organic acids in amniotic fluid near term were given by Raiha (1963), who used enzymic and colorimetric methods to determine lactate, pyruvate, 2-oxoglutarate and citrate concentrations in an investigation of neonatal metabolic acidosis. Silicic acid chromatography was also used to demonstrate the presence of citric, lactic and pyruvic acids. Typical concentrations observed were lactate 75.69 21.29 mg (100 ml) pyruvate 0.82 0.40 mg (100 ml) citrate 5.55 1.27 mg (100 ml) and 2-oxoglutarate 0.74 0.33 mg (100 ml) (all near-term). 

Table 8.1 Organic acids in amniotic fluid (from Hagenfeldt and Hagenfeldt, 1972) ( = 18, mean gestational age 17.6 weeks range 15-20 weeks).

Table 8.3 Quantitative levels of organic acids in amniotic fluid (DEAE-Sephadex extraction) (Chalmers and Lawson, unpublished). 

Chalmers, R.A., Lawson, A.M. and Raymond, F.D. (1979), Organic acids in human amniotic fluid and the prenatal diagnosis of the organic acidurias. Clin. ScL, 35, 5p. 

Raiha, N.C.R. (1963), Organic acids in fetal blood and amniotic fluid. Pediatrics, 1025. 

Williams, V.P., Ching, D.K. and Cederbaum, S.D. (1979), Absorption of organic acids from amniotic fluid and urine onto silica gel before analysis by gas chromatography and combined gas chromatography/mass spectrometry. Clin. Chem., 25,1814. 

Fig. 9.4 Chromatograms of organic acids extracted using DEAE-Sephadex from amniotic fluid obtained at 15-18 weeks gestation and chromatographed as their ethoxime and trimethylsilyl derivatives on 10 per cent OV-101 on HP Chromosorb W (80-100 mesh) by temperature progranuning from 110°C to 285 C at 4°C min with a 5 min initial isothermal delay. The chromatograms show the first part of the analysis and illustrate (from left to right) amniotic fluid containing none, 2, 5 and lO/ g of added methylmalonic acid ml of amniotic fluid.

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