Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is now a great deal of evidence to link genetic defects of pyruvate metabolism to brain disease. Experimental evidence is reviewed in Chapter 12, and clinical evidence has been reviewed above. Severe lesions of components of the pyruvate dehydrogenase complex are associated with severe generalized brain disease, and milder defects with inherited ataxias. Nearly half of one series of our ataxic patients had deficient activity of pyruvate dehydrogenase, and 40% of another series have deficient activity of the lipoamide dehydrogenase component. This last group corresponds to 60% of the patients with Friedreich's ataxia and its clinical variants at UCLA. There is an association between defective activity of lipoamide dehydrogenase and disease, and the data suggest there is a structural mutation of the gene for the enzyme. Preliminary studies suggest that obligate heterozygotes as a group have enzyme activities between those for controls and those for patients. Moreover, the obligate heterozygotes from families in which there are kinetic defects of lipoamide dehydrogenase also appear to have kinetic abnormalities of the enzyme. The ataxic patients with reduced lipoamide dehydrogenase activity currently fall into two clinical groups. One is ragged-red ataxia, and the other is a disorder that is a subgroup of the classic Friedreich's ataxia syndrome. Studies need to be undertaken on a larger group of patients, with more diverse inherited ataxias, to test the present clinical associations of the enzyme defect. A dietary treatment derived from a knowledge of the presumed defect has modified the ataxia that is associated with defects of pyruvate decarboxylase, but the diet has not yet been tested with defects of lipoamide dehydrogenase.
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PMID:Evidence for a primary defect of lipoamide dehydrogenase in Friedreich's ataxia. 10 55

A patient with congenital lactic acidosis, muscular hypotonia and severe ataxia is reported. The aetiology of his disease was found to be a deficiency of pyruvate dehydrogenase (E.C. 4.1.1.1.). Thiamine treatment (1.8 g/day) was successful in correcting biochemical and clinical symptoms. The mechanism of its action is probably based on activation of pyruvate dehydrogenase through interference in the physiologic regulation.
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PMID:Thiamine dependency in a patient with congenital lacticacidaemia due to pyruvate dehydrogenase deficiency. 41 46

Two brothers, aged 11 years 6 months and 2 years 3 months, with psychomotor and growth retardation, episodes of weakness, ataxia, ophthalmoplegia, and elevated levels of blood pyruvate were shown to have a deficiency in the pyruvate dehydrogenase complex (PDH). When they ate a diet high enough in fats to cause ketonemia but not acidosis, there was a fall in blood pyruvate levels, a decrease in the frequency and severity of the episodes of neurological deterioration, an increased rate of growth and development in the younger brother, and increased strength and endurance in the older one. The possibility of dietary treatment makes the early diagnosis of PDH deficiency more important. Determination of blood pyruvate and lactate levels following a standard glucose meal (glucose-pyruvate test) appears to be the most reliable screening test for this condition.
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PMID:Ketonic diet in the management of pyruvate dehydrogenase deficiency. 82 10

Defects of the pyruvate dehydrogenase complex and of mitochondrial fatty acid oxidation are important causes of disease. Defects of pyruvate dehydrogenase may present in early childhood with severe CNS changes or, as lactic acidosis or later with ataxia. Defects of fatty acid oxidation may present with hypoglycaemic coma, myopathy, liver disease with encephalopathy, cardiomyopathy or sudden infant death. The investigation of both these groups of disorders is difficult and depends upon a combination of biochemical and molecular biology techniques.
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PMID:Deficiency of the pyruvate dehydrogenase complex and of mitochondrial fatty acid oxidation. 196 58

We examined the pyruvate dehydrogenase (PDH) complex using bio- and immunochemical methods with cultured cells derived from 2 boys with mental retardation, ataxia, and primary lactic acidemia due to partial deficiency in the PDH complex. We found a defect in dephosphorylation and the subsequent activation of the E1 alpha subunit of the enzyme.
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PMID:Immunochemical analysis of pyruvate dehydrogenase complex in 2 boys with primary lactic acidemia. 238 45

Disturbances of pyruvate metabolism have been implicated in the aetiology of several neurological disorders including Leigh's disease and familial ataxia. We have re-investigated a patient whose initial description documented intermittent ataxia, a presumed disorder of pyruvate metabolism and an X-linked pattern of inheritance. Recent studies showed he had slow oxidation of pyruvate, low pyruvate dehydrogenase complex (PDC) activity and immunochemical evidence of E1 deficiency in skeletal muscle mitochondria. This is consistent with the recent finding that the gene for E1 alpha is on the X chromosome.
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PMID:Familial intermittent ataxia due to a defect of the E1 component of pyruvate dehydrogenase complex. 259 88

We have investigated electron transfer activities of respiratory chain complexes in platelet mitochondria of a patient with intermittent ataxia and lactic acidosis who was previously reported to be deficient in the E1 (decarboxylase) component of the pyruvate dehydrogenase complex. Electron transfer from succinate to cytochrome c was normal, but the mitochondria exhibited moderately decreased (63% of control) quinol: cytochrome-c oxidoreductase activity, suggesting a defect in complex III. Consistent with some perturbation in complex III, electron flux through complex III was resistant to inhibition by myxothiazol compared to normal controls. In contrast, titration with antimycin revealed a less abnormal pattern of inhibition. The extreme specificity of myxothiazol binding at or near the quinol oxidase domain of mitochondrial cytochrome b, i.e., b-566, suggests a defect in this region of complex III which may perturb the kinetics or thermodynamics of quinol oxidation in the complex. These data suggest that the patient's illness results from a mutation in the quinol oxidase domain of mitochondrial cytochrome b (b-566).
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PMID:Myxothiazol resistance in human mitochondria. 284 49

"Energy metabolism" is deranged in a wide variety of disorders of the nervous system. This term refers rather loosely to the pathways responsible for the utilization of the major substrates of brain. Primary disorders of energy metabolism are those in which the primary insult affects the cellular machinery required for energy metabolism. A typical example would be a defect in a gene coding for a mitochondrial protein. Biochemically, defects which appear to be hereditary and which lead to disease of the central nervous system have been described in each of the pathways of energy metabolism: glycogenolysis (the break-down of glycogen to glucose); glycolysis (the break down of glucose to pyruvate and lactate); the pyruvate dehydrogenase complex (which oxidizes pyruvate to enter the Krebs tricarboxylic acid cycle); the tricarboxylic acid cycle itself (which completes the oxidation of carbohydrates and other substrates to carbon dioxide); electron transport (which carries out their oxidation to water); the pentose phosphate pathway (an alternate pathway for glucose oxidation); and several "minor" mitochondrial pathways. Clinically, the spectrum of syndromes associated with primary disorders of energy metabolism is wide. Common manifestations include psychomotor retardation, with associated lactic acidosis and/or hypoglycemia. The laboratory abnormalities may be intermittent. Syndromes which have been culled out include congenital lactic acidosis, Leigh disease, intermittent ataxia, Kearns-Sayre-Shy syndrome (KSS), myoclonus epilepsy with ragged red fibers (MERRF), and mitochondrial myopathy-encephalopathy-lactic acidosis-stroke (MELAS). As with other families of inborn errors, both clinical and biochemical heterogeneity occur. Patients with apparently similar clinical syndromes can turn out to have different inborn errors, and patients with abnormalities of the same gene product can have clinically distinguishable syndromes. Secondary disorders are those in which the derangements of energy metabolism are presumably secondary to some other insult but may still be important for the cellular pathophysiology. These include the metabolic encephalopathies and probably a number of well-known neurodegenerative disorders. In the hereditary ataxias, abnormalities of mitochondrial markers are common but do not correlate consistently with the disorders as conventionally classified; a new classification into axonal ataxias, multiple system degenerations, and ataxic encephalopathies may be easier to relate to the pathophysiology.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Energy metabolism in disorders of the nervous system. 297 43

A simple and rapid method based on the NADH-linked reduction of a tetrazolium dye was described for the determination of pyruvate dehydrogenase activity in rat brain homogenates. The method (method 3) gave a value of 36.06 +/- 1.24 nmol of pyruvate utilised/min/mg of whole brain protein. This value was higher than that obtained by measurement of the rate of decarboxylation of [1-14C]pyruvate (15.10 +/- 0.88 nmol/min/mg of protein; method 1) and was comparable with the rate of transfer of acetyl groups to an arylamine (39.04 +/- 1.32 nmol/min/mg of protein; method 2). A critique of the values reported by others by different methods was given. The pyruvate dehydrogenase activity in the mitochondria isolated from rat brain was in the "active" (nonphosphorylated) form. A deficiency of thiamine in rats was produced by treatment with pyrithiamine, an antagonist of thiamine. This treatment resulted in abnormal neurological signs, such as ataxia and convulsions. The measurement of the total activity of pyruvate dehydrogenase in the brain by all three methods showed no significant change in the enzymic activity in thiamine-deficient rats after treatment with pyrithiamine. The activities of the enzyme in the brains of pair-fed animals were similar to those in the controls.
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PMID:Effect of a deficiency of thiamine on brain pyruvate dehydrogenase: enzyme assay by three different methods. 313 33

Chronic thiamine deprivation in the rat leads to selective neuropathological damage in brainstem structures whereas treatment with the central thiamine antagonist, pyrithiamine, results in more widespread damage. In order to further elucidate the neurochemical mechanisms responsible for this selective damage, the thiamine-dependent enzyme complex pyruvate dehydrogenase (PDHC) was measured in 10 brain structures in the rat during progression of thiamine deficiency produced by chronic deprivation or by pyrithiamine treatment. Feeding of a thiamine-deficient diet to adult rats resulted in 5-7 weeks in ataxia and loss of righting reflex accompanied by decreased blood transketolase activities. PDHC activities were selectively decreased by 15-30% in midbrain and pons (lateral vestibular nucleus). Thiamine treatment of symptomatic rats led to reversal of neurological signs and to concomitant reductions of the cerebral PDHC abnormalities. Daily pyrithiamine treatment led within 3 weeks to loss of righting reflex and convulsions and to decreased blood transketolase of a comparable magnitude to that observed in chronic thiamine-deprived rats. No significant regional alterations of PDHC, however, were observed in pyrithiamine-treated rats.
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PMID:Activities of thiamine-dependent enzymes in two experimental models of thiamine-deficiency encephalopathy: 1. The pyruvate dehydrogenase complex. 406 11


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