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Biomedical subjects

H R Scholte

Publications and source records attributed to H R Scholte.

At least 19 recordsLinked to original sources
PubMed1991

Confocal scanning laser microscopy of mitochondria: a possible tool in the diagnosis of mitochondrial disorders.

This paper describes a non-invasive method for the study of mitochondrial morphology in cultured human skin fibroblasts by confocal scanning laser microscopy after staining the mitochondria with 2-[4-(dimethylaminostyryl]-1-methylpyridinium iodide. This method is applied to compare mitochondria in fibroblasts from healthy individuals and from patients with mitochondrial myopathy. In most cases there is a striking swelling of the patient's mitochondria and a loss of fine structure. The results with respect to the potential of this method as a diagnostic tool are discussed.

Humans↗
PubMed1991

Neonatal cardiomyopathy and lactic acidosis responsive to thiamine.

A congestive cardiomyopathy was diagnosed in a girl at the age of 4 weeks. In the weeks following she developed general muscle hypotonia and plasma lactate increased to 8.5 mmol/L. Biochemical investigations of a muscle biopsy at the age of 3 months showed a deficiency in the oxidation of all substrates tested: pyruvate plus malate, 2-ketoglutarate and palmitate plus malate. After freezing and thawing of the homogenate and the addition of essential cofactors, the oxidation of the ketoacids normalized. The oxidation defect in the untreated homogenate can be explained by a deficiency in one of the cofactors (such as thiamine pyrophosphate, NAD+ or CoASH), or by a defect in the oxidative phosphorylation. Treatment with thiamine and carnitine resulted in a decrease in blood lactate to normal levels and a dramatic clinical improvement. Suspension of thiamine caused deterioration of her clinical condition and lactic acidaemia. The thiamine therapy was then continued. The girl is now 6 years old and in perfect health.

Acidosis, Lactic↗
PubMed1990

Oxidative phosphorylation in human muscle in patients with ocular myopathy and after general anaesthesia.

The fuel preference of human muscle mitochondria has been given. Substrates which are oxidized with low velocity cannot be used to detect defects in oxidative phosphorylation. After general anaesthesia, the oxygen uptake with the different substrates is much lower than after local analgesia. The latter was therefore used in the subsequent study. In 15 out of 18 patients with ocular myopathy, defects in oxidative phosphorylation could be detected in isolated muscle mitochondria prepared from freshly biopsied tissue. Measurement of the activity of segments of the respiratory chain in homogenate from frozen muscle showed no, or minor defects. In two of these patients showing exercise intolerance, decreased oxidation of NAD(+)-linked substrates and apparently normal mitochondrial DNA, further study revealed deficiency of pyruvate dehydrogenase in a girl with ptosis and a high Km of complex I for NADH in a man. Both patients responded to vitamin therapy.

Adolescent↗
PubMed1990

Primary carnitine deficiency.

Carnitine deficiency can be defined as a decrease of intracellular carnitine, leading to an accumulation of acyl-CoA esters and an inhibition of acyl-transport via the mitochondrial inner membrane. This may cause disease by the following processes. A. Inhibition of the mitochondrial oxidation of long-chain fatty acids during fasting causes heart or liver failure. The latter may cause encephalopathy by hypoketonaemia, hypoglycaemia and hyperammonaemia. B. Increased acyl-CoA esters inhibit many enzymes and carriers. Long-chain acyl-CoA affects mitochondrial oxidative phosphorylation at the adenine nucleotide carrier, and also inhibits other mitochondrial enzymes such as glutamate dehydrogenase, carnitine acetyltransferase and NAD(P) transhydrogenase. C. Accumulation of triacylglycerols in organs increases stress susceptibility by an exaggerated response to hormonal stimuli. D. Decreased mitochondrial acetyl-export lowers acetylcholine synthesis in the nervous system. Primary carnitine deficiency can be defined as a genetic defect in the transport or biosynthesis of carnitine. Until now only defects at the level of carnitine transport have been discovered. The most severe form of primary carnitine deficiency is the consequence of a lesion of the carnitine transport protein in the brush border membrane of the renal tubules. This defect causes cardiomyopathy or hepatic encephalopathy usually in combination with skeletal myopathy. In a patient with cardiomyopathy and without myopathy, we found that carnitine transport at the level of the small intestinal epithelial brush border was also inhibited. The patient was cured by carnitine supplementation. Muscle carnitine increased, but remained too low. This suggests that carnitine transport in muscle is also inhibited. Carnitine transport in fibroblasts was normal, which disagrees with literature reports for similar patients.

Carnitine↗
PubMed1990

[Pathogenesis and pathophysiology of carnitine deficiency, a predictable risk].

When patients suffer from hepato-encephalopathy, (cardio)myopathy, dystrophy, hypoglycaemia, some metabolic diseases and several other disease states, carnitine deficiency should be considered. In this article a survey is given of the pathophysiology, laboratory diagnostics, clinical symptomatology and some therapeutic approaches. Some different cases will be demonstrated.

Adult↗
PubMed1989

Carnitine deficiency, mitochondrial dysfunction and the heart. Identical defect of oxidative phosphorylation in muscle mitochondria in cardiomyopathy due to carnitine loss and in Duchenne muscular dystrophy.

Cardiomyopathies are often caused by a metabolic defect. Carnitine deficiency and mitochondrial defects in the metabolism of acyl-CoA, including defects in oxidative phosphorylation, start the same circular mechanism of mitochondrial doom. Patients with cardiomyopathy due to carnitine loss are cured by carnitine supplementation. In such a patient we found defective oxidative phosphorylation in isolated muscle mitochondria. The stimulation of the respiratory rate with all substrates by ADP was decreased, probably the cause of inhibition of the adenine nucleotide translocator by accumulating long-chain acyl-CoA. The same condition was encountered in patients with Duchenne muscular dystrophy, who often get cardiomyopathy in the course of the disease process.

Acetyl Coenzyme A↗
PubMed1989

Muscle carnitine level in endurance training and running a marathon.

Twenty sedentary volunteers (13 men and 7 women) who were subjected to an 18- to 20-month training program aimed at completing a marathon after the onset of training participated in this study. In the course of the training and after running a marathon, the content of total carnitine in the m. vastus lateralis did not change. The content of muscle total carnitine was not sex related. However, significant correlations were demonstrated between muscle total carnitine content and plasma urea and creatinine concentrations. Also a negative significant correlation was found between the content of muscle total carnitine and the plasma activity of CK before running a marathon.

Adaptation, Physiological↗
PubMed1989

Studies on the formation of lactate and pyruvate from glucose in cultured skin fibroblasts: implications for detection of respiratory chain defects.

We investigated the time course of the formation of lactate and pyruvate from glucose in cultured skin fibroblasts from controls, from a patient with a cytochrome c oxidase deficiency and from controls treated with inhibitors of the individual respiratory chain complexes. Fibroblasts from the patient and inhibitor treated fibroblasts produced more lactate and less pyruvate; this resulted in a significant increase in the lactate to pyruvate ratio, reflecting an increased cytosolic NADH/NAD+ redox state. We conclude that measurement of lactate and pyruvate production from glucose in cultured skin fibroblasts can be of value in the diagnosis of inherited diseases of the mitochondrial respiratory chain.

Cells, Cultured↗
PubMed1989

[Mitochondrial myopathy. Encephalopathy with lactic acidosis and cerebral infarction].

A 21 year-old man presented with a history of sudden onset of aphasia and headache. CT showed a left parietal hypodensity and pallidal calcifications. The ECG showed a Wolff-Parkinson-White's syndrome. The patient then developed successively focal epileptic seizures, temper disorders, a cardiomyopathy, a pepper and salt retinopathy with hemeralopia, a left hemiplegia, deafness, and fever of unexplained origin. Left carotid angiography showed thin, irregular or occluded branches of the middle and anterior cerebral arteries. Blood muscle enzymes, lactate and pyruvate, were elevated with acidosis. Muscle biopsy revealed a mitochondrial myopathy and blood chemistry showed a severe deficiency of respiratory chain enzymes. Death occurred after 28 months. This case showed the diagnostic features of Melas, with some elements of the Kearns-Sayre syndrome. To our knowledge, this is the first case were serial angiographies allowed demonstration of arterial changes capable of explaining cerebral infarctions.

Acidosis, Lactic↗
PubMed1988

Cardiomyopathy associated with carnitine loss in kidneys and small intestine.

A boy was first seen at the age of 1 year on account of congestive cardiomyopathy. Growth and development had been normal. Total plasma carnitine was extremely low (1.8 mumol/l; normal range: 25-64 mumol/l). No hypoglycaemia, lactic acidaemia or dicarboxylic aciduria were found. Other laboratory findings were unremarkable except for a slight deficiency in iron, vitamin D and vitamin E. Total muscle carnitine was 1.5% of normal; however, no signs or symptoms of myopathy could be detected. After carnitine loading, liver carnitine increased to 24% of normal. Isolated muscle mitochondria showed decreased oxidative capacity with all substrates tested. Stimulation of O2 uptake by adenosine diphosphate (ADP) was decreased. After loading with both intravenous and oral carnitine, there was a rise in plasma carnitine and a rapid loss in the urine and the faeces. These findings suggest a defect in the brush border carnitine transport system of the kidneys and of the small intestine. Renal clearance of carnitine was abnormally high. Therapy with 1 g oral L-carnitine/kg per day was instituted without any problems and the cardiac disease resolved within 3 months. The parents and the patient's five sibs also had low plasma carnitine but displayed no cardiomyopathy.

Cardiomyopathies↗