The IMP dehydrogenase catalysed reaction in erythrocytes of normal individuals and patients with hypoxanthine guanine phosphoribosyltransferase deficiency.
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Biomedical subjects
Publications and source records attributed to J M Trijbels.
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A 4 1/2 months old female baby was admitted to our hospital after an unexpected heart attack. Birth was in the 37th gestational week after an uneventful pregnancy and delivery by sectio, birth weight 1650 g, Apgar 9/10/10. In the following weeks the baby showed general muscle hypotonia, failure to thrive and sometimes an uncharacteristic heart murmur. Besides a chronic lactic acidemia we found a hypertrophic cardiomyopathy, cataract and small defects of the pigment epithelium of the retina. The CT-scan of the brain showed hypodense areas of both thalami and the mid-brain. Metabolic examination of two muscle specimens showed a deficiency of cytochrome-c-oxidase activity (I: 30, II: 20, normal: 73-284 mU/mg protein). So our patient may be the first case with an established defect in the respiratory chain suffering from cardiomyopathy, cataract and mitochondrial dysfunction. There is also a strong similarity to other encephalomyopathies especially to the Leigh-Syndrome.
Lafora disease is an autosomal recessive and progressive degenerative disorder of the central nervous system (CNS). The pathogenic mechanism has been presumed to be an inborn error of carbohydrate metabolism, although this has never been proved. In a case of proven Lafora disease, pyruvate metabolism, which has a central position in carbohydrate metabolism, was studied in body fluids under various conditions and in brain biopsy material. No abnormalities in this metabolic pathway were found. This finding plus earlier reports in the literature exclude a defect in glycolysis; thus, a disturbance of carbohydrate metabolism as the pathogenic mechanism of Lafora disease is unlikely.
In this study we present a patient with Canavan disease or Van Bogaert and Bertrand type of spongiform leukodystrophy, proven by brain biopsy. We performed morphological studies and biochemical assays on fresh homogenates of the grey and white matter. Quantitative neuromorphological analysis of the cortex showed normal values except for poor dendritic arborization of the inner layers. No signs of neuronal damage were observed. The Na-K-ATPase activity was increased. Pyruvate and ketone bodies oxidation rates and the activity of cytochrome-c oxidase were normal. We conclude that there is neither a primary neuronal damage nor a primary mitochondrial dysfunction in the oxidative processes despite the abnormal morphology of mitochondria in this disease.