Herman J Ten Brink

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We investigated the presence of hydroxyacid–oxoacid transhydrogenase (HOT), which catalyses the cofactor-independent conversion of γ-hydroxybutyrate (GHB) to succinic semialdehyde coupled to reduction of 2-ketoglutarate (2-KG) to D-2-hydroxyglutarate (D-2-HG), in human liver extracts employing [2H6]GHB and 2-KG as substrates. We measured incorporation of 2H(More)
A sensitive and selective analytical technique is described for the determination ofN-acetylaspartic acid in body fluids using stable isotope dilution in combination with positive chemical ionization mass spectrometry with selected ion monitoring. Control mean and ranges have been established: in urine 19.5 and 6.6–35.4 µmol/mmol creat.; in plasma 0.44 and(More)
ABSTRACT: A stable-isotope dilution assay has been developed for quantitation of D- and L-2-hydroxyglutaric acids in physiologic fluids. D- and L-2-hydroxyglutaric acids are separated as the O-acetyl-di-(o)-2-butyl esters. The method uses D,L-[3,3,4,4-2H4]-2-hydroxyglutaric acid as internal standard with ammonia chemical ionization, selected ion monitoring(More)
A series of in vivo experiments is described in which [1-13C]phytanic acid was given as an oral substrate to a healthy subject and two patients showing an impairment in phytanic acid degradation, one with Refsum's disease and one with Chondrodysplasia punctata. After intake of the substrate by the control in a dose of 20 mg/kg body weight, the production of(More)
Succinylacetone (SA) is a specific marker for the inherited metabolic disease, hepatorenal tyrosinemia. We developed a stable-isotope dilution liquid chromatography tandem mass spectrometry for the determination of SA in dried blood spots (DBS) and liquid urine using a (13)C(4)-SA as internal standard. SA was extracted, converted to the butyl ester and(More)
Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a saturated, branched-chain fatty acid which because of the occurrence of a fi-methyl group cannot undergo direct //-oxidation. Instead, phytanic acid is first subjected to e-oxidative decarboxylation, yielding pristanic acid and CO2 (Steinberg, 1989). Pristanic acid(More)
R. J. A. WANDERS 1., C. W. T. VAN ROERMUND 1, D. S. M. SCHOR 2, H. J. TEN BRINK 2 and C. JAKOBS 2 ~Academic Medical Centre, University of Amsterdam, Departments of Pediatrics and Clinical Chemistry; 2Free University of Amsterdam, Department of Pediatrics, Amsterdam, The Netherlands *Correspondence: Department of Pediatrics, Academic Medical Center,(More)
Peroxisomes are the metabolic sites of a variety of substrates that are poorly oxidized in mitochondria. Impairment of one or more peroxisomal functions results in serious disease. Most of the peroxisomal disorders present with severe neurological abnormalities like psychomotor retardation, hypotonia, seizures, hearing deficiencies and ocular involvement(More)
This was directly supplemented intravenously and there was a rapid improvement in her condition together with normalisation of the serum calcium concentration. Phosphate determination showed an abnormal high concentrat ion of 6.66mmol/1 (n = 1.62-3.07mmol/1) , which also normalised in a couple of days. A thorough investigation revealed a mistake in the(More)
L-2-Hydroxyglutaric aciduria: Normal L-2-hydroxyglutarate dehydrogenase activity in liver from two new patients R. J. A. Wanders1,2*, L. Vilarinho3, H. P. Hartung4, G. F. Hoffmann5, P. A. W. Mooijer2, G. A. Jansen2, J. G. M. Huijmans6, J. B. C. de Klerk7, H. J. ten Brink8, C. Jakobs8 and M. Duran9 University Hospital Amsterdam, Academic Medical Centre,(More)