PubMed Health⌕ Search

Biomedical subjects

R J Wanders

Publications and source records attributed to R J Wanders.

At least 289 records · Page 16Linked to original sources
PubMed1994

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency: a severe fatty acid oxidation disorder.

3-Hydroxyacyl-CoA dehydrogenase deficiency is a newly recognised fatty acid oxidation disorder with a usually fatal outcome. We present a further patient who presented with hypoketotic hypoglycaemia, hepatopathy, secondary carnitine deficiency and increased plasma long-chain acylcarnitines. 3-Hydroxydicarboxylic aciduria was present and the diagnosis confirmed in cultured skin fibroblasts. Our patient is compared with those reported in the literature with respect to clinical symptoms, differential diagnosis and possible therapeutic regimens.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1994

Clinical and biochemical characteristics of peroxisomal disorders: an update.

Peroxisomal disorders represent a recently recognized group of inherited diseases in man, now comprising 14 different disorders. If discussion is restricted to those peroxisomal disorders in which there is neurological involvement (thereby excluding hyperoxaluria and acatalasaemia), results over the least few years have shown that analysis of very-long-chain fatty acids (VLCFAs) is a highly reliable initial test to establish whether or not one is dealing with a peroxisomal disorder. Rhizomelic chondrodysplasia punctata, its recently identified variant form and glutaryl-CoA oxidase deficiency will show no abnormalities and must be identified by other means. Recently we have found a few clinically proven cases of adrenoleukodystrophy showing normal VLCFA in plasma but clearly abnormal values in fibroblasts. This suggests that great care is warranted in interpreting plasma VLCFA analyses. Furthermore, plasma bile acids, phytanic acid, pristanic acid and pipecolic acid should be analysed in any patient with clinical symptoms suggestive for a peroxisomal disorder but normal plasma VLCFAs.

Adrenoleukodystrophy↗
PubMed1994

Measurement of short-chain acyl-CoA dehydrogenase (SCAD) in cultured skin fibroblasts with hexanoyl-CoA as a competitive inhibitor to eliminate the contribution of medium-chain acyl-CoA dehydrogenase.

Short-chain acyl-CoA dehydrogenase (SCAD) deficiency has so far been reported in only very few patients. This is due, in part, to the problems involved in measuring the activity of SCAD unequivocally. The main reason for this difficulty is that butyryl-CoA, the substrate preferably used for SCAD activity measurements, is also dehydrogenated by medium-chain acyl-CoA dehydrogenase (MCAD). Elimination of this contribution can be achieved by means of immune precipitation with a specific MCAD antibody. We now describe a relatively straightforward assay based on the use of gas chromatography/mass spectrometry for detection. The contribution of MCAD to overall butyryl-CoA dehydrogenation was eliminated by adding excess hexanoyl-CoA to the assay medium. The validity of the method developed was checked by SCAD-activity measurements in fibroblasts from an established SCAD-deficient patient.

Acyl Coenzyme A↗
PubMed1994

A new type of peroxisomal disorder with variable expression in liver and fibroblasts.

We describe two siblings, presently 5 and 9 years of age, who had neurodegenerative symptoms after the first year of life. Although they lacked clinical characteristics of a peroxisomal disorder, they had elevated levels of plasma very long chain fatty acids, pipecolic and phytanic acids, and abnormal bile acid intermediates, which suggested a generalized peroxisome deficiency disorder. Immunocytochemical study and electron microscopy of the liver disclosed absence of peroxisomes in approximately 90% of hepatocytes. However, the remaining 10% of the hepatocytes had numerous normal-looking peroxisomes containing catalase activity and catalase antigen. Alanine glyoxylate aminotransferase and the peroxisomal beta-oxidation enzymes acyl-coenzyme A oxidase and 3-ketoacyl coenzyme A thiolase were also present in the organelles. Both cell types were grouped in clusters. In contrast to most of the liver cells, fibroblasts cultured from skin biopsy specimens had normal peroxisomal functions. Thus this defect in peroxisome biogenesis is characterized by variable expression in different tissues (liver vs fibroblasts), as well as within individual cells in the same tissue (liver mosaicism). Awareness of the heterogeneity in tissue expression of peroxisomal disorders could be of critical importance in prenatal diagnosis.

Child↗
PubMed1994

A new peroxisomal disorder with fetal and neonatal adrenal insufficiency.

A boy with a new type of adrenoleukodystrophy is described. This was characterised by fetal and neonatal adrenal insufficiency, a neurological picture as seen in neonatal adrenoleukodystrophy, but with a normal number of peroxisomes in the liver and a peroxisomal dysfunction limited to the very long chain fatty acids and pristanic acid.

Adrenal Insufficiency↗
PubMed1994

Mitochondrial trifunctional protein deficiency. Catalytic heterogeneity of the mutant enzyme in two patients.

We examined the enzyme protein and biosynthesis of human trifunctional protein harboring enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase activity in cultured skin fibroblasts from two patients with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency. The following results were obtained. (a) In cells from patient 1, immunoblot analysis and pulse-chase experiments indicated that the content of trifunctional protein was < 10% of that in control cells, due to a very rapid degradation of protein newly synthesized in the mitochondria. The diminution of trifunctional protein was associated with a decreased activity of enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase, when measured using medium-chain to long-chain substrates. (b) In cells from patient 2, the rate of degradation of newly synthesized trifunctional protein was faster than that in control cells, giving rise to a trifunctional protein amounting to 60% of the control levels. The 3-hydroxy-acyl-CoA dehydrogenase activity with medium-chain to long-chain substrates was decreased drastically, with minor changes in activities of the two other enzymes. These data suggest a subtle abnormality of trifunctional protein in cells from patient 2. Taken together, the results obtained show that in both patients, long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency is caused by an abnormality in the trifunctional protein, even though there is a heterogeneity in both patients.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1994

Re-evaluation of conditions required for measurement of true alanine:glyoxylate aminotransferase activity in human liver: implications for the diagnosis of hyperoxaluria type I.

In this paper we studied the glyoxylate-dependent transamination of L-alanine and L-glutamate in human liver homogenates in order to develop a reliable method for the determination of true alanine:glyoxylate aminotransferase activity in liver homogenates from patients suspected to suffer from hyperoxaluria type I. Measurements were made according to two protocols described in literature in control human liver homogenates which were either untreated or treated with an antiserum raised against purified alanine:glyoxylate aminotransferase. The results obtained show that enzyme activity can best be determined at pH 8.0 as compared to pH 7.4 since the former leads to a higher sensitivity of the method. Alanine:glyoxylate aminotransferase activities measured at pH 8.0 are approximately 50% higher compared to the enzyme activities measured at pH 7.4. Accordingly, it is proposed to measure alanine:glyoxylate aminotransferase activity at pH 8.0 using the newly determined correction factor as described in this paper.

Alanine↗
PubMed1994

beta-Oxidation enzymes in fibroblasts from patients with 3-hydroxydicarboxylic aciduria.

The activities of 3-hydroxyacyl-CoA dehydrogenase, enoyl-CoA hydratase, and 3-ketoacyl-CoA thiolase were measured in fibroblasts from eight patients with 3-hydroxydicarboxylic aciduria. Measurement of 3-hydroxyacyl-CoA dehydrogenase with 3-ketopalmitoyl-CoA as substrate provided conclusive evidence for a deficiency of the long-chain 3-hydroxyacyl-CoA dehydrogenase in seven of the patients. Measurement of the enzyme in the normal direction cannot be recommended because this gives a higher residual activity. A trifunctional enzyme protein is responsible for the 3-hydroxyacyl-CoA dehydrogenase as well as for the hydratase and thiolase activities. A slight decrease in one or both of the other two activities was observed in four of the seven deficient patients, indicating that a defect in the trifunctional enzyme protein may affect the three enzyme activities to different degrees.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1993

L-2-hydroxyglutarate dehydrogenase: identification of a novel enzyme activity in rat and human liver. Implications for L-2-hydroxyglutaric acidemia.

In this paper we studied the degradation of L-2-hydroxyglutarate in tissues from rat and man in order to try and find the underlying basis for the accumulation of this metabolite in L-2-hydroxyglutaric acidemia patients. The results show that L-2-hydroxyglutarate is not degraded by an oxidase but via a dehydrogenase which was found to be present in liver only. This newly identified enzyme activity was characterized kinetically, although the nature of the reaction product remains to be identified.

Alcohol Oxidoreductases↗
PubMed1993

Permeability properties of peroxisomes in digitonin-permeabilized rat hepatocytes. Evidence for free permeability towards a variety of substrates.

In order to investigate the permeability properties of rat-liver peroxisomes in situ, we selectively permeabilized hepatocytes with digitonin in a medium mimicking the cytosol. This system permitted us to study the latency of peroxisomal oxidases by means of measurement of their activities in permeabilized compared to disrupted hepatocytes. The activity of peroxisomal oxidases was studied using three different methods: (1) measurement of the oxidase-mediated production of H2O2 in a system containing homovanillic acid, horseradish peroxidase and azide; (2) measurement of the rate of substrate utilization or product formation; (3) measurement of the production of H2O2 via the peroxidative action of catalase in the presence of an excess of methanol. The results obtained depended on which system was used to measure the activity of the different oxidases. Our observations lead us to conclude that method 1 cannot be used for latency studies, whereas methods 2 and 3 are suitable under defined circumstances. Based on the results of methods 2 and 3, we conclude that urate oxidase, L-alpha-hydroxyacid oxidase A and D-amino acid oxidase show no structure-linked latency in digitonin-permeabilized hepatocytes, suggesting that the substrates for these enzymes permeate freely through the peroxisomal membrane.

Alcohol Oxidoreductases↗
PubMed1993

Studies on the effect of fenoprofen on the activation and oxidation of long chain and very long chain fatty acids in hepatocytes and subcellular fractions from rat liver.

We studied the effect of fenoprofen on the activation of palmitic acid (C16:0), lignoceric acid (C24:0) and cerotic acid (C26:0) in microsomal and peroxisomal fractions from rat liver. Fenoprofen was found to inhibit the formation of palmitoyl-CoA in both microsomal and peroxisomal fractions whereas the formation of lignoceroyl-CoA and cerotoyl-CoA was not inhibited at all. In freshly isolated rat hepatocytes palmitic acid beta-oxidation was progressively inhibited at increasing concentrations of fenoprofen, most probably due to its inhibitory effect on palmitoyl-CoA synthetase activity. On the other hand, fenoprofen was also found to inhibit the beta-oxidation of lignoceric acid and cerotic acid in rat hepatocytes. It is shown that the acyl-CoA oxidase activity with lignoceroyl-CoA as substrate was inhibited by fenoprofen whereas the palmitoyl-CoA and pristanoyl-CoA oxidase activities were not inhibited by fenoprofen. This finding provides an explanation for the inhibitory effect of fenoprofen on lignocerate and cerotate beta-oxidation in hepatocytes.

Animals↗
PubMed1993

Studies on mitochondrial oxidative phosphorylation in permeabilized human skin fibroblasts: application to mitochondrial encephalomyopathies.

In this report we describe that the functional capacity of the mitochondrial oxidative phosphorylation system can be studied in cultured skin fibroblasts permeabilized with a limited amount of digitonin. By using a variety of different oxidizable substrates, information can be obtained on the functional activity of complex I, for instance, which is important since different diseases in man have recently been identified in which complex I is deficient. The method described may contribute to the biochemical characterization of patients suffering from one of a variety of encephalomyopathies.

Adenosine Triphosphate↗
PubMed1993

The CoA esters of 2-methyl-branched chain fatty acids and of the bile acid intermediates di- and trihydroxycoprostanic acids are oxidized by one single peroxisomal branched chain acyl-CoA oxidase in human liver and kidney.

Rat liver peroxisomes contain three acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins; pristanoyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids (e.g. pristanic acid); and trihydroxycoprostanoyl-CoA oxidase, which oxidizes the CoA esters of the bile acid intermediates di- and trihydroxycoprostanic acids (Van Veldhoven, P. P., Vanhove, G., Asselberghs, S., Eyssen, H. J., and Mannaerts, G. P. (1992) J. Biol. Chem. 267, 20065-20074). In the present report we demonstrate that human liver peroxisomes contain only two acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins, and a novel branched chain acyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids as well as those of the bile acid intermediates (which also possess a 2-methyl substitution in their side chains). The branched chain acyl-CoA oxidase was purified to near homogeneity by means of column chromatography. It appeared to be a 70-kDa monomeric protein that did not cross-react with antisera raised against rat palmitoyl-CoA oxidase and pristanoyl-CoA oxidase. No indication was found for the presence of a separate trihydroxycoprostanoyl-CoA oxidase in human liver. The branched chain acyl-CoA oxidase was present also in human kidney, suggesting that it is expressed in other extrahepatic tissues as well. Our results explain a number of clinical-chemical observations made in certain cases of peroxisomal beta-oxidation disorders.

Acyl Coenzyme A↗
PubMed1993

Studies on phytanic acid alpha-oxidation in rat liver and cultured human skin fibroblasts.

We have studied the alpha-oxidation of phytanic acid in rat liver and human skin fibroblasts in order to try to resolve the controversial issue of the subcellular site of alpha-oxidation of phytanic acid. The results show that isolated mitochondria are able to alpha-oxidize phytanic acid whereas isolated peroxisomes show no phytanic acid alpha-oxidation activity. Intact hepatocytes were found to alpha-oxidize phytanic acid at a rate which is more than 20-fold higher than the activity found in postnuclear supernatant fractions incubated under optimal conditions. The alpha-oxidation of phytanic acid was found to be sensitive to inhibitors of the respiratory chain and an uncoupler of oxidative phosphorylation. Furthermore, the alpha-oxidation of phytanic acid was found to be deficient in cultured human skin fibroblasts with an inherited deficiency of cytochrome c oxidase and in fibroblasts with a deficiency of functional peroxisomes. We conclude that mitochondria are indispensable for phytanic acid alpha-oxidation. Furthermore, we propose that one (or more) of the partial reactions in phytanic acid alpha-oxidation proceeds in peroxisomes leading to the concept that phytanic acid oxidation in the intact cell requires the participation of both mitochondria and peroxisomes.

Adenosine Triphosphate↗
PubMed1993

Subcellular fractionation of cultured normal human melanocytes: new insights into the relationship of melanosomes with lysosomes and peroxisomes.

In order to obtain information on the disputed nature of melanosomes a comparison was made between the localization of melanosomal markers with those of other well-defined subcellular organelles such as lysosomes and peroxisomes. The distribution of marker enzymes was studied using two different density gradient systems, i.e., Percoll and Nycodenz. Furthermore, the subcellular localization of various types of antigens was analyzed using indirect immunofluorescence and immuno-electron microscopy. All methods revealed the existence of partial co-localization of melanosomal and lysosomal proteins and different localization of peroxisomal markers. The results suggest that melanosomes may share a common origin with lysosomal structures.

Cell Fractionation↗
PubMed1993

Differentiation and proliferation of respiration-deficient human myoblasts.

Replication and transcription of mitochondrial DNA were impaired in dividing human myoblasts exposed to ethidium bromide. MtDNA content decreased linearly per cell division and mitochondrial transcript levels declined rapidly, resulting in respiration-deficiency of the myoblasts. Despite the absence of functional mitochondria the cells remained able to proliferate when grown under specific culture conditions. However, the formation of myotubes was severely impaired in respiration-deficient myoblasts. We conclude that differentiation of myoblasts into myotubes is more dependent on mitochondrial function than proliferation of myoblasts.

Adenosine Triphosphate↗