A novel method to determine small intestinal barrier function in human neonates in vivo.
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Enterocolitis, Necrotizing↗
Biomedical subjects
H Schierbeek
Publications and source records attributed to H Schierbeek.
Hereditary tyrosinaemia type I: a long-term study of the relationship between the urinary excretions of succinylacetone and delta-aminolevulinic acid.
Patients with hereditary tyrosinaemia type I (HT) excrete large amounts of succinylacetone (SA) in urine. Owing to structural resemblance of SA to delta-aminolevulinic acid (ALA), SA inhibits the second enzyme in the pathway for haeme biosynthesis, porphobilinogen synthase, resulting in increased urinary ALA excretion. We investigated the relationship between urinary SA and ALA excretions of two patients with different forms of HT (late-infantile and juvenile). In both patients the urinary SA and ALA excretions showed a more or less inverse correlation. The patient with the early-infantile form of HT had a relatively greater increase in urinary SA and ALA excretions in comparison to the patient with the juvenile form of HT. A possible explanation for this unexpected inverse correlation between the urinary excretion of SA and ALA might be a lack of intramitochondrial glycine, a substrate for delta-aminolevulinic acid synthesis. It has been reported previously that high concentrations of SA reversibly and competitively inhibit the transport of glycine through membranes.
Amino Acid Metabolism, Inborn Errors↗
Stable isotope dilution analysis of cystine in granulocyte suspensions as cysteine: a powerful method for the diagnosis, the follow-up, and treatment of patients with cystinosis.
A stable isotope dilution method was developed for the determination of cystine in granulocytes. Granulocytes were isolated from blood samples of treated cystinosis patients. Cystine in the granulocyte suspension was decoupled from proteins and converted to cysteine by treatment with a tri-butyl phosphine solution. Tertiary butyldimethyl silyl derivatives were prepared and analyzed by gas chromatography/mass spectrometry. Selective ion monitoring was carried out at m/z 304.3 (M-159 and m/z 406.4 (M-57) for the natural, and at m/z 306.3 and 408.4 for the labelled compound. [3,3,3',3'-2H]-DL-cystine was used as internal standard for the isotope dilution analysis. Concentrations of cystine in granulocytes could be accurately measured. There was a distinct difference in cystine concentrations in healthy individuals and treated patients.
Adolescent↗
Determination of succinylacetone and succinylacetoacetate in physiological samples as the common product 5(3)-methyl-3(5)-isoxazole propionic acid using an isotope dilution method and mass spectrometry.
A stable isotope dilution method was developed for the determination of succinylacetone and succinylacetoacetate in physiological samples. Succinylacetone and succinylacetoacetate were both converted to 5(3)-methyl-3(5)-isoxazole propionic acid by treating them with a solution of hydroxylamine-HCl at a pH less than 3 and at 80 degrees C. After extraction with diethyl ether tertiary butyldimethyl silyl derivatives were prepared using N-methyl-N-t. butyldimethyl silyl-trifluoro acetamide and analyzed by gas chromatography mass spectrometry. Selective ion monitoring was carried out at m/z 138.1 (M-131) and m/z 212.1 (M-57) for the natural, and at m/z 139.1 and 213.1 for the labelled compound. (15N)-5(3)-methyl-3(5)-isoxazole propionic acid was synthesized and used as internal standard for the isotope dilution analysis. Concentrations in physiological samples as low as 10 nmol/l could be accurately measured.
Acetoacetates↗
Age-related accumulation of phytanic acid in plasma from patients with the cerebro-hepato-renal (Zellweger) syndrome.
Plasma samples from several Zellweger patients were found to contain elevated phytanic acid levels. It was subsequently found that the level of phytanic acid in plasma from Zellweger patients depends upon the age of the patients at the time of sampling. In patients 17 weeks of age or younger, plasma phytanic acid levels were found to be normal, whereas in patients 40 weeks of age or older plasma phytanic acid levels were found to be elevated. The relationship between the age of the patients at sampling and the level of phytanic acid in the patients' plasma is probably the resultant of dietary intake of phytanic acid combined with a defective catabolism of this compound.
Age Factors↗
Capillary gas chromatographic profiling of urinary, plasma and erythrocyte sugars and polyols as their trimethylsilyl derivatives, preceded by a simple and rapid prepurification method.
A capillary gas chromatographic method for the profiling of trimethylsilylated mono- and disaccharides and polyols in urine, plasma and unwashed and washed erythrocytes is described. The prepurification method is based on the moderate inhibition of the derivatization experienced in the presence of physiological amounts of inorganic salts and the relative stability of the formed trimethylsilylethers towards treatment with water and dilute hydrochloric acid. Series to series quality control data for 31 sugars/polyols in a pooled urine are given. The method was used to establish age-dependent concentrations of 18 sugars/polyols in urines of 72 control persons on a free diet. Gas chromatographic profiles and quantitative data obtained from urines of pediatric patients with galactosemia treated with a diet low in lactose and galactose, type 1 hereditary tyrosinemia treated with a diet low in phenylalanine and tyrosine, and a neurological disorder with a high calorie gastric drip feeding, are presented and discussed. Examples of the profiling of sugars/polyols in the plasma, unwashed and washed erythrocytes of a healthy adult, and the plasma of a newborn with galactosemia prior to treatment, are given.
Adolescent↗
Mevalonic aciduria: an inborn error of cholesterol biosynthesis?
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Cerebellar Ataxia↗