Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.3 (complex I)
 8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We reported a girl with mitochondrial encephalomyopathy, who had various neuromuscular symptoms including dilated cardiomyopathy, generalized convulsions, myoclonus, muscular weakness and growth retardation. Lactate levels in the serum and CSF were elevated. Muscle biopsy showed scattered ragged-red fibers, and complex I (NADH-CoQ reductase) and complex IV (cytochrome c oxidase) were markedly reduced. Although she was treated with coenzyme Q, DL-carnitine and sodium succinate, she died of progressive congestive heart failure at 9 10/12 years of age.
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PMID:[A case of mitochondrial encephalomyopathy with cardiomyopathy due to decreased complex I and IV activities]. 255 57

We report an autopsy case of a 19 year-old man with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) a subgroup of mitochondrial encephalomyopathy presenting cardiomyopathy. He had repeatedly suffered from transient unconsciousness, hemiplegia, hemianopsia and convulsion attacks since the age of 9, and he died of severe congestive heart failure. In laboratory findings, blood lactate and pyruvate were markedly increased. Skeletal muscle biopsy demonstrated numerously scattered ragged-red fibers with modified Gomori's trichrome staining. Enzymatic activities of the mitochondrial respiratory chain showed a marked decrease of NADH cytochrome c reductase (complex I). In postmortem examination, the heart was 310g in weight and had right ventricular dilatation. Microscopically, degenerated and scattered myocardial cells (ragged-red fibers), interstitial edema and microvascular hyperplasia were demonstrated in the myocardium. Under the electron microscope, abnormal mitochondria proliferated and myofibrils were unusually sparse. Immunohistochemical studies with specific antibodies against the mitochondrial electron transfer enzyme subunits revealed a reduction of immunoreactive materials for complex I in the myocardium. These results suggested the relationship of myocardial disorders and decreased activity of complex I in electron transfer enzymes in this patient.
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PMID:[A study of myocardial disorders in an autopsy case of mitochondrial encephalomyopathy]. 846 36

Mitochondrial (mt)DNA defects, both deletions and tRNA point mutations, have been associated with cardiomyopathies. The aim of the study was to determine the prevalence of pathological mtDNA mutations and to assess associated defects of mitochondrial enzyme activity in dilated cardiomyopathy (DCM) patients with ultrastructural abnormalities of cardiac mitochondria. In a large cohort of 601 DCM patients we performed conventional light and electron microscopy on endomyocardial biopsy samples. Cases with giant organelles, angulated, tubular, and concentric cristae, and crystalloid or osmiophilic inclusion bodies were selected for mtDNA analysis. Mutation screening techniques, automated DNA sequencing, restriction enzyme digestion, and densitometric assays were performed to identify mtDNA mutations, assess heteroplasmy, and quantify the amount of mutant in myocardial and blood DNA. Of 601 patients (16 to 63 years; mean, 43.5 +/- 12.7 years), 85 had ultrastructural evidence of giant organelles, with abnormal cristae and inclusion bodies; 19 of 85 (22.35%) had heteroplasmic mtDNA mutations (9 tRNA, 5 rRNA, and 4 missense, one in two patients) that were not found in 111 normal controls and in 32 DCM patients without the above ultrastructural mitochondrial abnormalities. In all cases, the amount of mutant was higher in heart than in blood. In hearts of patients that later underwent transplantation, cytochrome c oxidase (Cox) activity was significantly lower in cases with mutations than in those without or controls (P = 0.0008). NADH dehydrogenase activity was only slightly reduced in cases with mutations (P = 0.0388), whereas succinic dehydrogenase activity did not significantly differ between DCM patients with mtDNA mutations and those without or controls. The present study represents the first attempt to detect a morphological, easily identifiable marker to guide mtDNA mutation screening. Pathological mtDNA mutations are associated with ultrastructurally abnormal mitochondria, and reduced Cox activity in a small subgroup of non-otherwise-defined, idiopathic DCMs, in which mtDNA defects may constitute the basis for, or contribute to, the development of congestive heart failure.
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PMID:Mitochondrial DNA mutations and mitochondrial abnormalities in dilated cardiomyopathy. 981 42

Oxidative stress in the myocardium may play an important role in the pathogenesis of congestive heart failure (HF). However, the cellular sources and mechanisms for the enhanced generation of reactive oxygen species (ROS) in the failing myocardium remain unknown. The amount of thiobarbituric acid reactive substances increased in the canine HF hearts subjected to rapid ventricular pacing for 4 weeks, and immunohistochemical staining of 4-hydroxy-2-nonenal ROS-induced lipid peroxides was detected in cardiac myocytes but not in interstitial cells of HF animals. The generation of superoxide anion was directly assessed in the submitochondrial fractions by use of electron spin resonance spectroscopy with spin trapping agent, 5, 5'-dimethyl-1-pyrroline-N-oxide, in the presence of NADH and succinate as a substrate for NADH-ubiquinone oxidoreductase (complex I) and succinate-ubiquinone oxidoreductase (complex II), respectively. Superoxide production was increased 2.8-fold (P<0.01) in HF, which was due to the functional block of electron transport at complex I. The enzymatic activity of complex I decreased in HF (274+/-13 versus 136+/-9 nmol. min(-1). mg(-1) protein, P<0.01), which may thus have caused the functional uncoupling of the respiratory chain and the deleterious ROS production in HF mitochondria. The present study provided direct evidence for the involvement of ROS in the mitochondrial origin of HF myocytes, which might be responsible for both contractile dysfunction and structural damage to the myocardium.
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PMID:Mitochondrial electron transport complex I is a potential source of oxygen free radicals in the failing myocardium. 1045 64

An Argentine male child died at 4.5 years of age of a lethal mitochondrial disease associated with a MELAS mutation and a Barth syndrome-like presentation. The child had severe failure to thrive from the early months and for approximately two years thereafter. In addition, the patient had severely delayed gross motor milestones, marked muscle weakness, and dilated cardiomyopathy that progressed to congestive heart failure. He also had persistently elevated urinary levels of 3-methylglutaconic and 2-ethylhydracrylic acids and low blood levels of cholesterol. Detailed histopathologic evaluation of the skeletal muscle biopsy showed high activity of succinate dehydrogenase, a generalized decrease of COX activity, and abundant ragged-red fibers. Electron microscopic studies revealed multiple mitochondrial abnormalities in lymphocytes and monocytes, in the striated muscle, and in the postmortem samples (muscle, heart, liver, and brain). Biochemical analysis showed a pronounced and constant lactic acidosis, and abnormal urinary organic acid excretion (unchanged in the fasting and postprandial states). In addition, in CSF there was a marked increase of lactate and beta-hydroxybutyrate (beta-HOB) and also a high systemic ratio beta-HOB/acetoacetate. Enzymatic assay of the respiratory chain in biopsied muscle showed 10% of complex I activity and 24% of complex IV activity compared with controls. Molecular studies of the mitochondrial genome revealed an A to G mutation at nucleotide pair 3243 in mitochondrial DNA, a well-known pathogenetic mutation (MELAS mutation) in all the patient's tissues and also in the blood specimens of the probands mother and sibs (4 of 5). The diagnosis of MELAS mutation was reinforced by the absence of an identifiable mutation in the X-linked G4.5 gene of the propositus. The present observation gives additional evidence of the variable clinical expression of mtDNA mutations in humans and demonstrates that all clinical variants deserve adequate investigation to establish a primary defect. It also suggests adding Barth-like syndrome to the list of phenotypes with the MELAS mutation.
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PMID:Barth's syndrome-like disorder: a new phenotype with a maternally inherited A3243G substitution of mitochondrial DNA (MELAS mutation). 1124 64

Congestive heart failure (CHF) causes arrhythmogenic, structural and contractile remodeling, with important atrial-ventricular differences: atria show faster and greater inflammation, cell-death and fibrosis. The present study assessed time-dependent left atrial (LA) and ventricular (LV) gene-expression changes in CHF. Groups of dogs were submitted to ventricular tachypacing (VTP, 240 bpm) for 24 h or 2 weeks, and compared to sham-instrumented animals. RNA from isolated LA and LV cardiomyocytes of each dog was analyzed by canine-specific microarrays (>21,700 probe-sets). LA showed dramatic gene-expression changes, with 4785 transcripts significantly-altered (Q<5) at 24-hour and 6284 at 2-week VTP. LV gene-changes were more limited, with 52 significantly-altered at 24-hour and 130 at 2-week VTP. Particularly marked differences were seen in ECM genes, with 153 changed in LA (e.g. approximately 65-fold increase in collagen-1) at 2-week VTP versus 2 in LV; DNA/RNA genes (LA=358, LV=7); protein biosynthesis (LA=327, LV=14); membrane transport (LA=230, LV=8); cell structure and mobility (LA=159, LV=6) and coagulation/inflammation (LA=147, LV=1). Noteworthy changes in LV were genes involved in metabolism (35 genes; creatine-kinase B increased 8-fold at 2-week VTP) and Ca(2+)-signalling. LA versus LV differential gene-expression decreased over time: 1567 genes were differentially expressed (Q<1) at baseline, 1499 at 24-hour and 897 at 2-week VTP. Pathway analysis revealed particularly-important changes in LA for mitogen-activated protein-kinase, apoptotic, and ubiquitin/proteasome systems, and LV for Krebs cycle and electron-transfer complex I/II genes. VTP-induced CHF causes dramatically more gene-expression changes in LA than LV, dynamically altering the LA-LV differential gene-expression pattern. These results are relevant to understanding chamber-specific remodeling in CHF.
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PMID:Marked differences between atrial and ventricular gene-expression remodeling in dogs with experimental heart failure. 1880 23