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Biomedical subjects

C Jakobs

Publications and source records attributed to C Jakobs.

At least 271 records · Page 15Linked to original sources
PubMed1991

Pristanic acid does not accumulate in peroxisomal acyl-CoA oxidase deficiency: evidence for a distinct peroxisomal pristanyl-CoA oxidase.

The concentration of pristanic acid was measured in plasma from a patient with an isolated peroxisomal very long chain fatty acid (VLCFA) acyl-CoA oxidase deficiency, a defect in peroxisomal beta-oxidation resulting in accumulation of VLCFA in plasma and tissues. Although peroxisomes are believed to be involved in pristanic acid beta-oxidation, the pristanic acid level in the patient's plasma was within the control range. This finding provides evidence for the existence of a pristanyl-CoA oxidase distinct from the specific trihydroxycholestanoyl-CoA and VLCFA acyl-CoA oxidases.

Acyl-CoA Oxidase↗
PubMed1991

Renal failure in adult patients with hereditary tyrosinaemia type I.

An adult patient with hereditary tyrosinaemia type I who developed renal failure is reported. She received a renal transplant at the age of 23 years. In childhood her kidney disease was dominated by multiple tubular defects with resulting hypophosphataemic rickets. Metabolic acidosis was the most prominent feature in the years preceding the transplantation. Her kidneys were contracted to 40 g. The major morphological finding was that of a tubulointerstitial nephropathy. Liver biopsies taken at the ages of 5.5 and 23 years showed cirrhotic changes. Crystalloid inclusions in the liver mitochondriae were a prominent finding on electron microscopy. Fumarylacetoacetase was deficient in liver, kidneys, fibroblasts and lymphocytes. The typical biochemical parameters of tyrosinaemia, succinylacetone, p-hydroxyphenyllactate, p-hydroxyphenylpyruvate and serum tyrosine were only slightly elevated. A brief history of a second adult tyrosinaemia patient with decreasing renal function is also given.

Adolescent↗
PubMed1991

Infantile isolated sulphite oxidase deficiency: report of a case with negative sulphite test and normal sulphate excretion.

We present the clinical and biochemical data of a patient with infantile isolated sulphite oxidase deficiency with late onset of symptoms. A comparison of the biochemical parameters is made with the neonatal type of this disease and with the data of described patients with the combined defect of sulphite oxidase and xanthine oxidase, due to molybdenum cofactor deficiency. False-negative sulphite dip stick test as a pitfall in the diagnosis of sulphite oxidase deficiency is discussed.

Humans↗
PubMed1991

Characterization of oxygen-resistant Chinese hamster ovary cells. III. Relative resistance of succinate and alpha-ketoglutarate dehydrogenases to hyperoxic inactivation.

We have recently shown that exposure of Chinese hamster ovary (CHO) cells to a toxic dose of normobaric hyperoxia (98% O2 for 3 days) caused a disturbance of cellular energy metabolism, that is, respiratory failure followed by stimulation of glycolytic activity and a net depletion of ATP. Respiratory failure was correlated with a selective inactivation of three mitochondrial enzymes, that is, partial inactivation of NADH dehydrogenase and virtually complete inactivation of succinate and alpha-ketoglutarate dehydrogenase activities (Schoonen et al., 1990). To elucidate the biochemical basis of resistance to hyperoxia in a previously described oxygen-resistant substrain of Chinese hamster ovary (CHO) cells, we compared the resistant cells with wildtype CHO cells with respect to several key parameters of oxidative and glycolytic energy metabolism. The two cell types were critically different in that the succinate and alpha-ketoglutarate dehydrogenases of the oxygen-resistant cells were relatively resistant to inactivation by hyperoxia, which may at least partly explain their enhanced capacity to respire and survive under hyperoxic conditions. Although the biochemical basis for the observed enzyme resistance to hyperoxic inactivation remains to be elucidated, the present data underscore the importance of succinate and alpha-ketoglutarate dehydrogenases as critical targets in hyperoxic killing of wildtype CHO cells.

Adenosine Triphosphate↗
PubMed1991

[Pearson's syndrome: a multi-system disorder based on a mt-DNA deletion].

In 1979 Pearson described a syndrome, in which the main symptoms were severe sideroblastic anemia and exocrine pancreas dysfunction. The aetiology was still unknown. A decade later, the Pearson syndrome can be described as a lethal multisystem disorder, in which the bone marrow and exocrine pancreas show major dysfunction, but also other organs (like kidneys, liver, gut and skin) can be affected. These patients also show growth retardation. The study of the mitochondrial DNA allowed identification of a deletion in the mitochondrial DNA. The case of a patient suffering from Pearson's syndrome is reported.

Acidosis, Lactic↗
PubMed1990

Stable isotope dilution analysis of very long chain fatty acids in plasma, urine and amniotic fluid by electron capture negative ion mass fragmentography.

A sensitive and selective stable isotope dilution electron capture negative ion chemical ionization mass fragmentography method applying pentafluorobenzyl derivatives was developed for the accurate quantitation of very long chain fatty acids. This technique allowed detection of 1-5 pg of each compound and was applied to plasma (100 microliters), amniotic fluid (1 ml) and urine (1 ml). Normal concentrations were established and the concentrations in samples of selected patients with classified peroxisomal disorders were determined. In plasma samples of all patients the C26:0/C22:0 ratios were elevated (range 0.03-0.43), compared to the control ratios (range 0.003-0.021). The ratio C26:0/C22:0 was elevated in four of five amniotic fluid samples from fetuses with peroxisomal disorders (range 0.18-0.54) when compared with controls (range 0.05-0.25). An elevation of the ratio C26:1/C22:0 was observed in all five amniotic fluid samples (range 0.22-0.60 vs. 0-0.08 in controls). Urinary C26:0 concentrations were lower than in plasma and amniotic fluid and diagnostic ratios were not elevated in patients with peroxisomal disorders.

Adolescent↗
PubMed1990

Identification of pristanoyl-CoA oxidase activity in human liver and its deficiency in the Zellweger syndrome.

The ability of human liver to oxidize pristanic acid was investigated. Liver from control subjects was found to contain pristanic acid oxidase activity, an H2O2-producing enzyme activity not previously demonstrated in mammals. In livers from patients with the cerebro-hepato-renal syndrome of Zellweger, a genetic disease characterized by the absence of morphologically distinguishable peroxisomes, pristanic acid oxidase activity was found to be deficient. These results indicate that pristanic acid is oxidized in peroxisomes rather than in mitochondria as believed until now. Furthermore, our findings provide an explanation for the elevated levels of pristanic acid in body fluids from patients lacking peroxisomes.

Acyltransferases↗
PubMed1990

Respiratory failure and stimulation of glycolysis in Chinese hamster ovary cells exposed to normobaric hyperoxia.

Continuous exposure of Chinese hamster ovary (CHO) cells to an atmosphere of 98% O2, 2% CO2 (normobaric hyperoxia) leads within a period of several days to cytostasis and clonogenic cell death. Here we report respiratory failure as an important early symptom of oxygen intoxication in CHO cells, resulting in a more than 80% inhibition of oxygen consumption within 3 days of hyperoxic exposure. This inhibition appeared to be correlated with selective inactivation of three mitochondrial key enzymes, NADH dehydrogenase, succinate dehydrogenase, and alpha-ketoglutarate dehydrogenase. The latter enzyme controls the influx of glutamate into the Krebs cycle and is particularly critical for oxidative ATP generation in most cultured cells, which depends on exogenous glutamine rather than glucose as a carbon source. As expected, the inactivation of alpha-ketoglutarate dehydrogenase was correlated with a fall in cellular glutamine utilization, which became apparent from the first day of hyperoxic exposure. Thereafter, glucose utilization and lactate excretion started to increase, up to 3-fold, indicating a cellular response to respiratory failure aimed at increased ATP generation from glycolysis. However, in spite of this response, the cellular ATP level progressively decreased, up to 2.5-fold. Thus, killing of CHO cells by normobaric hyperoxia seems to be due to a severe disturbance of mitochondrial metabolism eventually leading to a depletion of cellular ATP pools.

Adenosine Triphosphate↗
PubMed1990

Stable isotope dilution analysis of 4-hydroxybutyric acid: an accurate method for quantification in physiological fluids and the prenatal diagnosis of 4-hydroxybutyric aciduria.

A quantitative assay for 4-hydroxybutyric acid was developed using D6-4-hydroxybutyric acid as an internal standard. 4-Hydroxybutyric acid was isolated by liquid chromatography and the amount quantified by selected ion monitoring, ammonia chemical ionization gas chromatography/mass spectrometry of the trimethylsilyl derivatives. The concentrations of 4-hydroxybutyric in control physiological fluids were: 2.64 +/- 3.46 mmol mol-1 creatinine in urine, 1.09 +/- 2.87 mumol l-1 in plasma, 0.98 +/- 1.17 mumol l-1 in cerebrospinal fluid and 1.28 +/- 0.47 mumol l-1 in amniotic fluid. The concentration of 4-hydroxybutyric acid in the amniotic fluid from a pregnancy at risk for 4-hydroxybutyric aciduria was 2.30 mumol l-1, indicating an unaffected fetus. The stable isotope dilution assay of 4-hydroxybutyric acid in physiological fluid samples is a rapid, sensitive and accurate method for quantification, as well as a valuable technique for the prenatal diagnosis of 4-hydroxybutyric aciduria.

Acidosis↗