Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three children displaying hypotonia, cardiac involvement and defects of the mitochondrial respiratory chain complexes are reported. The first case showed severe neonatal hypotonia, failure to thrive, hepatomegaly, dilation of the right cardiac cavities, profound lactic acidosis and amino aciduria. The boy died at the age of 7 weeks. In the second case hypotonia, severe cardiomyopathy, cyclic neutropenia, lactic acidosis and 3-methylglutaconic aciduria occurred. The boy died at the age of 27 months. The third case presented at the age of 16 months as an acute hypokinetic hypertrophic cardiomyopathy with transient hypotonia and mild lactic acidosis. Spontaneous clinical remission occurred. In all cases muscle biopsy was performed. Morphological studies failed to show ragged-red fibers but there was lipid storage myopathy and decreased cytochrome c oxidase activity. Biochemical studies confirmed the cytochrome c oxidase deficiency in muscle in all cases. It was associated with complex I III deficiency in case 1 and with severe deficits of all respiratory chain complexes in case 2. Post-mortem studies in case 1 indicated that complex IV was reduced in the liver but not in the heart and quantitative analysis of mtDNA revealed a depletion in muscle. Cases 1 and 2 shared some clinical features with fatal infantile myopathy associated with cytochrome c oxidase deficiency, while case 3 displayed a very unusual clinical presentation. The histochemical enzyme reaction of cytochrome c oxidase is useful for the diagnosis of mitochondrial myopathy because ragged-red fibers may be lacking. Finally, biochemical measurement of the different mitochondrial respiratory chain complexes is required because multiple defects are frequent and occasionally related to mtDNA depletion.
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PMID:Defects of the mitochondrial respiratory chain complexes in three pediatric cases with hypotonia and cardiac involvement. 132 Jun 61

Using in situ hybridization and histochemistry we have studied muscle biopsy samples from eight patients with mitochondrial encephalomyopathies and known defects of mitochondrial DNA (mtDNA). In four patients with heteroplasmic mtDNA deletions there were focal accumulations of deleted mtDNA and its transcripts within ragged red fibres (RRF). In one of these, a probe designed specifically to detect deleted mtDNA identified abundant deleted mtDNA and its fusion transcript in RRF and lesser accumulations in non-ragged red cytochrome oxidase (COX) deficient fibres. A further patient with a deletion involving the heavy strand promoter region showed accumulation of deleted mtDNA and light strand transcripts in RRF, but concomitant depletion of all heavy strand transcripts. In all patients with deletions, normal mtDNA transcripts were depleted in COX deficient fibres irrespective of ragged red change. Deleted mtDNA was rare or absent in normal fibres. Within RRF, COX activity was more profoundly impaired in patients with deletions involving COX subunits. In two patients heteroplasmic for the base pair (bp) 3243 mutation associated with mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes (MELAS), RRF contained a great excess of mtDNA and transcripts of all species. Some RRF showed excess COX activity. Non-ragged red COX deficient fibres showed equal increases of ribosomal RNA (rRNA) and messenger RNA, suggesting that focal biochemical defects were not associated with a quantitative defect of transcription termination at the 3' end of the 16S rRNA which might be predicted. A patient heteroplasmic for the bp 8344 mutation (associated with myoclonic epilepsy and ragged red fibres: MERRF) showed subnormal COX activity within RRF, although the tissue distribution of mtDNA and its transcripts was similar to that seen with the bp 3243 mutation. Within mitochondrial encephalomyopathies, the relationships between the distribution and expression of abnormal mtDNA and the focal biochemical consequences are complex and heterogeneous.
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PMID:A molecular genetic study of focal histochemical defects in mitochondrial encephalomyopathies. 160 73

A 5-month-old boy died of progressive heart failure that started at the age of 3 months. Autopsy revealed a mitochondrial cardiomyopathy and a mitochondrial myopathy of the limb muscle and diaphragm. Cytochemically random defects of cytochrome c oxidase were visualized by light and electron microscopy in the diaphragm and especially the heart muscle, the limb muscle showing a diffuse attenuation whereas the liver and kidneys reacted normally. The activities of NADH-dehydrogenase (complex I) and cytochrome c oxidase (complex IV) were severely diminished (20% residual activity of controls) in the skeletal and heart muscle. In the heart, succinate cytochrome c reductase (complex II/III) was additionally decreased to the same degree. Loss of cytochrome c oxidase activity was based on a reduction of both mitochondrial and nuclear derived subunits in the heart and diaphragm as revealed by immunohistochemical analysis, whereas the limb muscle showed a normal immunoreactive protein content. The results illustrate heterogeneous tissue expression of respiratory chain enzyme defects and demonstrate that a cardiomyopathy may be the leading presentation of a mitochondrial disorder in early infancy.
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PMID:Fatal infantile mitochondrial cardiomyopathy and myopathy with heterogeneous tissue expression of combined respiratory chain deficiencies. 165 34

During a 4-year period 1984 to 1988, 20 children referred with manifestations of central nervous system or neuromuscular disease combined with hyperlactatemia were found to have a mitochondrial disease. Each diagnosis was based on the results of thorough biochemical and morphologic investigations. The patients were separated into one series with mainly encephalopathy (n = 14) and another with mainly myopathy (n = 6). The patients with encephalopathy had the following syndromes: Kearns-Sayre (n = 2), MERRF (myoclonus epilepsy and ragged red fibers; n = 2), MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes; n = 3), Alpers (n = 3), Leigh (n = 1), and other variants (n = 3). In patients with myopathy, three had hypertrophic nonobstructive cardiomyopathy. Ultrastructural abnormalities of mitochondria were the most common morphologic changes in the muscle biopsies. Complex I deficiency was most common in the patients with encephalopathy. All of the patients with myopathy had complex IV deficiency. Mutations of mitochondrial DNA were found in six patients with encephalopathy. We conclude that identification of defects at the DNA level and determination of the phenotypic expression with clinical, morphologic, and biochemical methods are fundamental for future rational classification of mitochondrial disorders.
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PMID:Mitochondrial encephalomyopathies in childhood. II. Clinical manifestations and syndromes. 186 Dec 10

Chronic pancreatitis is described in a 10-year-old boy with mitochondrial myopathy due to cytochrome c oxidase (complex IV) deficiency. There have been few reports of chronic pancreatitis associated with congenital metabolic diseases. Marked pancreatic calcifications and pseudocysts of the pancreatic head and tail were demonstrated by computed tomography of the abdomen and by endoscopic retrograde pancreatography, which were thought to be useful methods for morphological examination of the pancreas. In the patient, no possible etiological factors were identified, including anomalous pancreatobiliary ductal junction or biochemical abnormalities. The association between cytochrome c oxidase deficiency and chronic pancreatitis remains to be established.
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PMID:Chronic pancreatitis in muscular cytochrome c oxidase deficiency. 217 84

Electron microscopic examination of muscle specimens taken at biopsy in 6 patients with complex I deficiency and 1 patient with an unknown primary chemical defect who had the clinical characteristics of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) revealed striking abnormalities in blood vessels in 5. Abnormalities consisted of an increased number of enlarged mitochondria with complicated cristae in the pericytes of capillaries, endothelial cells, and smooth muscle cells of the small arteries, including terminal arterioles and precapillary sphincters, predominantly in smooth muscle cells. On statistical analysis, the number of mitochondria and the ratio of mitochondrial area to the total area of the smooth muscle cells were increased approximately tenfold (p less than 0.001). Although stroke-like episodes were not present, similar mitochondrial abnormalities in blood vessels were found in 1 patient who had the encephalomyopathic form of complex IV deficiency and in 2 patients in whom the primary chemical defects could not be clearly defined. Such abnormalities in small arteries might be responsible for the occasional occurrence of transient cerebral ischemia causing stroke-like episodes and progressive mental deterioration.
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PMID:Vascular involvement in mitochondrial myopathy. 250 Aug 89

Respiratory chain enzymes were studied in isolated mitochondria of two patients with mitochondrial myopathy. Both patients had been suffering from chronic progressive external ophthalmoplegia and abnormal muscular fatigability since late childhood. One of the patients exhibited the complete triad of symptoms characteristic of Kearns-Sayre syndrome. Venous lactate levels at rest and during minimal exercise were increased in both patients. Histochemical examination of muscle revealed ragged red fibres and intermingled fibres negative for cytochrome c oxidase. Biochemical studies showed decreased activities of complex I and complex IV of the respiratory chain in both patients. Reduced minus oxidized spectra of mitochondrial cytochromes revealed a decreased content of cytochrome aa3 in only one patient, but a normal content in the other. A combined deficiency of complexes I and IV in muscle might either be due to a deficiency of a single subunit common to both complexes or to a coincidental deficiency of both complexes expressed either in the same or in different fibres.
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PMID:Partial deficiency of complexes I and IV of the mitochondrial respiratory chain in skeletal muscle of two patients with mitochondrial myopathy. 254 13

The yeast box-mutant W7 exhibits deficiencies in cytochrome b and in nuclear coded complex III subunits, a phenotype observed previously in a patient with mitochondrial myopathy. DNA sequence analysis of mutant W7 revealed a single base transition in the cytochrome b gene; the mutated residue Gly 131 is perfectly conserved in all known cytochromes b and belongs to the Qo domain. Mutant W7 provides a model system for evaluating the action of therapeutic agents, such as vitamin K3 which restored NADH-oxidase activity in the mutant as well as in the antimycin-inhibited wild type. However, with the mutant, a greater quantity of menadione was necessary due to a decrease in other complex activities, and a much lower electron-flow fraction passed through cytochrome oxidase.
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PMID:Electron-transfer restoration by vitamin K3 in a complex III-deficient mutant of S. cerevisiae and sequence of the corresponding cytochrome b mutation. 255 31

Ultrastructural localization of mitochondrial electron transport enzymes in biopsied muscle from a patient with mitochondrial myopathy was studied. We applied the immunoelectron microscopic technique using colloidal-gold labeled antibodies. The results demonstrated a very distinct and dense labeling by gold particles of complexes I, III, and IV in the inner mitochondrial membrane. The density of gold particles reacted to complex IV was cleanly decreased. This result was correlated with the decreased biochemical activity of complex IV. Labeling on the paracrystalline inclusions was substantially decreased in abnormal giant mitochondrial, but gold particles were extensively confined on the membrane of cristae surrounding the inclusions.
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PMID:[Ultrastructural immunocytochemical localization of electron-transport enzymes in mitochondrial myopathy]. 255 30

The mitochondrial myopathies give rise to a diverse group of clinical syndromes, variably involving skeletal muscle and the central nervous system, with onset in childhood or adult life. In vitro studies of mitochondrial metabolism have identified a variety of functional defects of the respiratory chain, predominantly affecting complex I or complex III in adults, and complex IV in children. The increased incidence of maternal, as opposed to paternal, transmission in familial mitochondrial myopathy has led to the suggestion that these disorders may be caused by mutations of mitochondrial (mt) DNA. This hypothesis is derived from observations that mtDNA encodes subunits of the respiratory chain proteins and is exclusively maternally transmitted. Analysis of muscle mtDNA shows two populations, one normal and the other deleted by up to nearly half its length, in about 40% of cases of mitochondrial myopathy. Only a single normal length population of mtDNA is seen in blood from these patients, and in blood and muscle from control subjects. Patients with muscle mtDNA deletions reported to date have all presented with progressive external ophthalmoplegia, including some with the Kearns-Sayre syndrome. They rarely have affected relatives. Deletions are not detected in cases of proximal myopathy alone, or those with adult onset syndromes predominantly affecting the central nervous system. There is no clear correlation between the deleted coding regions and the biochemical defects; even patients with seemingly identical muscle mtDNA deletions may be clinically and biochemically heterogeneous.
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PMID:Mitochondrial myopathies. 268 27


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