Clinical and biochemical studies on cytochrome oxidase deficiencies.
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Animals↗
Biomedical subjects
S DiMauro
Publications and source records attributed to S DiMauro.
Immunocytochemical study of nebulin in Duchenne muscular dystrophy.
We used antibodies to nebulin in immunocytochemical studies. In normal muscle, nebulin was localized at the I band. The protein was also present in most fibers from all 15 Duchenne muscular dystrophy (DMD) patients studied, including patients who seemed to lack nebulin in electrophoretic gels and patients who demonstrated deletions of DNA in the region of Xp21. These results conform to other evidence that nebulin is not the primarily affected gene product in DMD; it may be affected secondarily.
Child↗
Late-onset muscle phosphofructokinase deficiency.
A 75-year-old man had a 10-year history of slowly progressive limb weakness without cramps or myoglobinuria. Clinical, morphologic, and biochemical studies showed muscle phosphofructokinase (PFK) deficiency. Erythrocyte PFK activity in his asymptomatic daughter was 63% of normal, compatible with a carrier state. The chronic myopathic variant of muscle PFK deficiency appears to be transmitted as an autosomal recessive trait and may be due to a distinct genetic defect.
Aged↗
Deletions of mitochondrial DNA in Kearns-Sayre syndrome.
We have identified large-scale deletions in muscle mitochondrial DNA (mtDNA) in seven of seven patients with Kearns-Sayre syndrome (KSS). We found no detectable deletions in the mtDNA of ten non-KSS patients with other mitochondrial myopathies or encephalomyopathies, or three normal controls. The deletions ranged in size from 2.0 to 7.0 kb, and did not localize to any single region of the mitochondrial genome. The proportion of mutated genomes in each KSS patient ranged from 45% to 75% of total mtDNA. There was no correlation between the size or site of the deletion, biochemical abnormality of mitochondrial enzymes, or clinical severity. The data bolster arguments that KSS is a unique disorder and genetic in origin.
Adolescent↗
Kearns-Sayre syndrome in twins: lethal dominant mutation or acquired disease?
We studied twin brothers who met all diagnostic criteria for the Kearns-Sayre syndrome (KSS). The twins reinforce the view that KSS is a specific syndrome. They raise the possibility that the condition is inherited as a lethal dominant trait, a mode of inheritance that explains the observed paucity of familial cases. However, these cases do not exclude the possibility of an acquired cause, such as persistent viral infection of the brain.
Adult↗
Biochemical and molecular aspects of cytochrome C oxidase deficiency.
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Amino Acid Sequence↗
Isolation of a cDNA encoding the muscle-specific subunit of human phosphoglycerate mutase.
We have isolated a full-length cDNA specifying the muscle-specific subunit of human phosphoglycerate mutase (PGAM-M). The cDNA encodes a deduced protein 253 amino acids in length and contains an unusually short (37 nucleotides) 3'-untranslated region. The deduced human PGAM-M protein is clearly related to yeast PGAM and to human diphosphoglycerate mutase. Genomic Southern analysis using the PGAM-M cDNA as a probe implies the presence of a large PGAM gene family in the human genome, while Northern analysis demonstrates tissue-specific transcription of this isoenzyme gene.
Amino Acid Sequence↗
[Rhabdomyolysis caused by carnitine palmitoyltransferase deficiency].
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Acyltransferases↗
Is nebulin the defective gene product in Duchenne muscular dystrophy?
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Child↗
Cytochrome c oxidase deficiency in Leigh syndrome.
We studied 6 mitochondrial enzymes in crude extracts and isolated mitochondria from 5 children with pathologically proven subacute necrotizing encephalomyelopathy (Leigh syndrome). Samples were taken from brain (5 patients), skeletal muscle (4 patients), liver (4 patients), kidney (4 patients), heart (1 patient), and cultured fibroblasts (3 patients). An isolated defect of cytochrome c oxidase (COX) activity was found in brain (decrease of activity to 15 to 39% of the normal mean), muscle (9 to 20%), kidney (1 to 67%), and in the 1 available heart (4%) from a patient with cardiopathy. COX activity was also decreased in liver of 3 patients (2 to 13% of normal) and in cultured fibroblasts of 2 patients (18 and 27%), but it was normal in both liver and fibroblasts from 1 patient. Immunotitration using polyclonal antibodies against human heart COX showed essentially normal amounts of cross-reacting enzyme protein in various tissues from different patients. Electrophoresis of COX immunoprecipitated from brain mitochondrial extracts showed normal patterns of COX subunits in 2 patients. This study confirms the theory that COX deficiency is an important cause of Leigh syndrome.
Brain↗
High serum levels of creatine kinase: asymptomatic prelude to distal myopathy.
Two brothers and an unrelated man had serum creatine kinase values of 3000-8000 units when they were asymptomatic, and there was no weakness on examination. EMG and muscle biopsy showed changes indicative of myopathy. Years later, all three developed weakness that was limited to the gastrocnemius. Because siblings were affected, the disorder can be regarded as a form of muscular dystrophy. The distribution of weakness, serum enzyme changes, and histologic changes resembled an autosomal recessive distal myopathy first described by Miyoshi and differed from many other reported cases of distal myopathy. Our cases also indicate that myopathy may be asymptomatic.
Adolescent↗
Myo-, neuro-, gastrointestinal encephalopathy (MNGIE syndrome) due to partial deficiency of cytochrome-c-oxidase. A new mitochondrial multisystem disorder.
A 42-year-old woman had a 10-year history of external ophthalmoplegia, malabsorption resulting in chronic malnutrition, muscle atrophy and polyneuropathy. Computer tomography revealed hypodensity of her cerebral white matter. A metabolic disturbance consisted of lactic acidosis after moderate glucose loads with increased excretion of hydroxybutyric and fumaric acids. Post-mortem studies revealed gastrointestinal scleroderma as the morphological manifestation of her malabsorption syndrome, ocular and skeletal myopathy with ragged red fibers, peripheral neuropathy, vascular abnormalities of meningeal and peripheral nerve vessels. Biochemical examination of the liver and muscle tissues revealed a partial defect of cytochrome-c-oxidase (complex IV of the respiratory chain). This mitochondrial multisystem disorder may represent a separate entity to be classified between the spectrum of myoencephalopathies and oculo-gastrointestinal muscular dystrophy.
Adult↗
Mitochondrial myopathies.
The mitochondrial myopathies or encephalomyopathies with known biochemical defects can be divided into 5 groups: (1) defects of mitochondrial transport, such as CPT deficiency or carnitine deficiencies; (2) defects of substrate utilization, such as PDHC deficiency or defects of beta-oxidation; (3) defects of the Krebs cycle, such as fumarase deficiency; (4) defects of oxidation-phosphorylation coupling, such as Luft disease, and (5) defects of the respiratory chain. These disorders are reviewed, with particular emphasis on the defects of the respiratory chain. Defects of complex I, III and IV show remarkable clinical and biochemical heterogeneity. All 3 complexes contain some subunits encoded by mtDNA and others encoded by nuclear DNA. At least some of the cytoplasmically made subunits appear to be tissue specific and may be developmentally regulated, thus explaining the genetic heterogeneity of these disorders.
Adenosine Triphosphatases↗
Peripheral neuropathy in mitochondrial disease.
Clinical, electrophysiological, histological and biochemical studies of two patients with mitochondrial disease revealed a moderately advanced axonal neuropathy with mitochondrial paracrystalline inclusions in Schwann cells, fibroblasts and muscle fibers. In addition there was a myopathy, and the activity of muscle cytochrome c oxidase was diminished by more than 50%. There were electrophysiological signs of myopathy, neuropathy and failure of excitation-contraction coupling in both patients. The partial enzyme deficiency raises some questions as to its pathogenetic role in these neuromyopathies.
Adult↗
Isolation of a cDNA clone encoding subunit IV of human cytochrome c oxidase.
We have isolated a full-length human liver cDNA clone specifying the nuclear-encoded subunit IV of the human mitochondrial respiratory chain enzyme, cytochrome c oxidase (COX; EC 1.9.3.1). The human cDNA clone is highly homologous to its bovine counterpart in the coding regions for both the mature polypeptide and the presequence, and the gene is evolving more slowly than that of any of the three mitochondrially encoded COX subunit genes. We find no preliminary evidence for tissue-specific isoforms of COX subunit IV, as Northern analysis of muscle, liver, and HeLa cell RNA shows an identically sized transcript in each cell type.
Amino Acid Sequence↗
Severe cardiopathy in branching enzyme deficiency.
A 7 1/2-year-old girl had exercise intolerance and exertional dyspnea. Four months later, congestive heart failure developed, with recurrent chylous pleural effusions, and she died at age 8 1/2 years. Endomyocardial biopsy tissue showed abundant PAS-positive, diastase-resistant cytoplasmic deposits. Similar inclusions were seen in muscle, skin, and liver specimens. Postmortem studies showed that the abnormal polysaccharide was especially abundant in heart and muscle, but was also present in all other tissues, including the central nervous system. Glycogen isolated from heart, muscle, and spinal cord showed a shift of the iodine spectrum toward higher than normal wavelengths. Branching enzyme activity was lacking in the muscle biopsy specimen and in all postmortem tissues; glycogenolytic enzymes had normal activities. These studies show that cardiomyopathy can be the first symptom of generalized branching enzyme deficiency and that the degree of accumulation of the abnormal polysaccharide may vary in different tissues.
Biopsy↗
Biochemical studies in mitochondrial encephalomyopathy.
The alpha-keto acid dehydrogenase complex and its component enzymes, lactate dehydrogenase, pyruvate carboxylase, cytochrome c oxidase, succinate-cytochrome c reductase, NADH-cytochrome c reductase, and the concentration of cytochromes and enzymes of beta-oxidation in muscle from a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes were studied and no specific defect was found. These results raise the possibility that the mitochondrial changes in the patient may be secondary.
Acidosis, Lactic↗
Characterization of the enzymatic defect in late-onset muscle phosphofructokinase deficiency. New subtype of glycogen storage disease type VII.
Human phosphofructokinase (PFK) exists in tetrameric isozymic forms, at least in vitro. Muscle and liver contain homotetramers M4 and L4, respectively, whereas red cells contain five isozymes composed of M (muscle) and L (liver) type subunits, i.e., M4, M3L, M2L2, and ML3, and L4. Homozygous deficiency of muscle PFK results in the classic glycogen storage disease type VII characterized by exertional myopathy and hemolytic syndrome beginning in early childhood. The genetic lesion results in a total and partial loss of muscle and red cell PFK, respectively. Characteristically, the residual red cell PFK from the patients consists of isolated L4 isozyme; the M-containing hybrid isozymes are completely absent. In this study, we investigated an 80-yr-old man who presented with a 10-yr history of progressive weakness of the lower limbs as the only symptom. The residual red cell PFK showed the presence of a few M-containing isozymes in addition to the predominant L4 species, indicating that the genetic lesion is a "leaky" mutation of the gene coding for the M subunit. The presence of a small amount of enzyme activity in the muscle may account for the atypical myopathy in this patient.
Aged↗