Quantitative amino acids in amniotic fluid and maternal plasma in early and late pregnancy. Preliminary report

Antenatal Growth, Gestational Age, Birth, Enteral Feeding, and Blood Citrulline Levels in Very Low Birth Weight Infants

Early enteral nutrition using reliable biomarkers of intestinal function must be established to improve neurodevelopmental outcomes in very low birth weight infants (VLBWIs). Serum citrulline levels reflect the intestinal function in adults. To elucidate the relationship among antenatal growth, postnatal enteral nutrition, and blood citrulline levels, a retrospective single-center observational study was conducted on 248 VLBWIs born between April 2014 and March 2021. A mixed effect model and post hoc simple slope analysis were used to estimate the correlations between clinical variables and citrulline levels at Early (day 5.1) and Late (day 24.3) postnatal ages. Greater gestational age, birth weight, and amount of enteral nutrition at the time of blood sampling were associated with lower citrulline levels at the Early postnatal age and higher citrulline levels at the Late postnatal age. Provided that Early citrulline levels predominantly reflect the consequence of antenatal citrulline metabolism, it is suggested that fetal growth and maturation are likely to promote citrulline catabolism in utero and its synthesis after birth. With additional insights into the temporal transition point wherein the maturation-dependent balance of citrulline metabolism shifts from catabolism-dominant to synthesis-dominant, citrulline emerges as a potential biomarker for assessing intestinal function and gastrointestinal disorders.

Successful pregnancy outcome in atypical hyperglycinaemia

A female patient with atypical nonketotic hyperglycinaemia is reported having undergone two successful pregnancies. During pregnancy, plasma glycine was raised. Neuropsychometric outcome of both offspring shows IQs average for population.

Gestational age-related reference values for amniotic fluid amino acids: a useful tool for prenatal diagnosis of aminoacidopathies

In this study we have measured the concentration of 24 amino acids and total homocysteine in amniotic fluids obtained between the tenth and 32nd week of gestation from pregnancies not at risk for metabolic diseases. These results are used as reference values to which are compared values obtained from pregnancies at risk for citrullinaemia, argininosuccinic aciduria, HHH (hyperornithinaemia, hyperammonaemia and homocitrullinaemia) syndrome, cobalamin metabolism disorders (CblC or CblD), and sulphite oxidase deficiency. We discuss the helpfulness of amino acid analysis in amniotic fluid for prenatal diagnosis of aminoacidopathies.

Maternal nutrition and obstetric outcome

In general, maternal nutritional status in civilized countries is not at risk. However, even a marginal malnutritional state for some (micro)nutrients for the pregnant women can adversely affect obstetrical outcome. From the data available so far, only folic acid supplementation is advised. However, the importance of an adequate iron and zinc status has to be stressed. In addition, women should be warned preconceptionally about excessive intake of vitamins, especially of those products containing large amounts of vitamin A.

Quantification of human amniotic fluid constituents by high resolution proton nuclear magnetic resonance (NMR) spectroscopy

We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal alpha-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mM phosphate buffer and 6.02 mM disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were 'NMR visible' in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 microM. Good agreement with literature values based on other analytical techniques was obtained.

Serum free amino acids of healthy males and pregnant women from Ethiopia

Several clinical, anthropometric and biochemical parameters have been used for the evaluation of the nutritional status and diagnosis of protein-energy malnutrition [1]. Analysis of the complete serum amino-acid spectrum by ion-exchange chromatography provides valuable information on the adequacy of protein intake and on the metabolic response to protein depletion in undernourished subjects. However, the serum aminogram is quite differently affected by acute or chronic starvation or the great variety of starchy but low-protein foods and further toxic factors (e.g. mycotoxins) leading to kwashiorkor. Thus, very complex alterations of the serum amino-acid spectrum had to be expected [5, 9] and stimulated the present investigation for reference purposes. We report the results of amino acid determinations in apparently healthy adult males and pregnant women taking the traditional Ethiopian diet. For want of a better evaluation of the specific nutritional influence, we also collected data on serum amino acids of healthy Ethiopians consuming an average European diet.

Maternal homocystinuria: studies of an untreated mother and fetus

A 20-year-old woman with untreated homocystinuria was examined when she was 18 weeks' pregnant. Amniocentesis was performed and raised levels of homocystine and methionine were present in the amniotic fluid. Assay of cystathionine synthetase activity in cultured amniotic fluid cells showed the carrier state for homocystinuria. An abortion was performed because of the possible adverse effects of continuing the pregnancy both for the mother and the fetus. No pathological abnormality was found in the aborted fetus. Further data are needed to assess the possible teratogenic effects of maternal homocystinuria and the adverse consequences of pregnancy in the affected mother.

Free amino acids in plasma throughout pregnancy

Plasma amino acid analyses on 27 amino acids in serial samples from 15 pregnancies in 14 patients are reported. Variations of amino acid levels with gestational age are reported both for absolute amino acid levels and for levels normalized to total amino acids, with a t test used to determine which amino acids vary significantly. The extent to which individual results differ from the means is indicated. Correlation and regression analyses were done for each amino acid vs. every other amino acid and for each amino acid vs. gestational age. Significant differences were found in amino acid results for plasma from an individual in whom pregnancy resulted in spontaneous abortion.

Amino acid composition of amniotic fluid in intrahepatic cholestasis of pregnancy, pre-eclampsia and rhesus incompatibility

The levels of free amino acids in amniotic fluid were determined in twenty patients with normal pregnancy, five with intrahepatic cholestasis of pregnancy, twelve with pre-eclampsia, and four with rhesus incompatibility. In pre-eclampsia there was no significant change in the amino acid composition of the amniotic fluid. In recurrent intrahepatic cholestasis the concentration of 15 out of the 22 amino acids studied was significantly higher than normal and the mean concentration of 4 others was more than 20 per cent above normal without this being statistically significant. In rhesus incompatibility there was a significant decrease in the concentration of 13 amino acids, and a decrease of more than 20 per cent in the mean concentration of 5 others.