Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Mitochondrial disorder is an inborn error of metabolism affecting the cellular respiratory chain. Defective energy production leads to a wide variety of clinical manifestations (ataxia, epilepsy, dementia, myopathy, polyneuropathy, retinal pigment anomalies, and cardiomyopathy with conduction anomalies). Hearing loss is a regular feature and is often the first clinical symptom. Audiologic data from 26 members of a family in three generations is presented. One of these patients was examined for the biochemical error. Respiratory study of muscle biopsy revealed a mild defect in the NADH-ubiquinone oxidoreductase step of the oxidative phosphorylation (complex I). The content of cytochrome aa3 (complex IV) was also reduced. Adult onset sensorineural hearing loss starting in the high frequency region progresses with a fairly constant speed in this family. A cochlear type of hearing loss is found in the less pronounced cases. Advanced cases present features of retrocochlear affection with decreasing speech recognition, elevated acoustic reflex thresholds, and increased ABR latency with derangement of potentials. Caloric sensitivity was unaffected.
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PMID:Audiologic findings in a family with mitochondrial disorder. 180 40

A case of mitochondrial encephalomyopathy (Kearns-Sayre syndrome) with corneal endothelial abnormality is reported. A 22-year-old woman had retinitis pigmentosa, external ophthalmoplegia, complete heart block, ataxia, muscle weakness, dementia, sensorineural hearing loss, and was of short stature. Renal dysfunction, diabetes mellitus, and amenorrhea were also observed. Biopsy revealed decreased cytochrome c oxidase (complex IV) activity in muscle mitochondria. The corneal endothelium examined by specular microscope showed decreased cell density, severe polymegathism, and pleomorphism in both eyes. To our knowledge, this is the first report concerning primary corneal endothelial abnormality in a case with mitochondrial encephalomyopathy. The corneal endothelium is one of the tissues that could be affected by the enzyme deficiency present in this disease.
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PMID:Corneal endothelium in a case of mitochondrial encephalomyopathy (Kearns-Sayre syndrome). 274 82

Abnormalities of cerebral oxidative metabolism were investigated in "animal models" of Parkinson disease by in situ optical measurements of local cerebral blood volume and cytochrome oxidase redox shifts in rats two weeks after unilateral 6-hydroxydopamine lesions of the substantia nigra with or without interruption of ascending noradrenergic pathways. The data demonstrate oxidative metabolic dysfunction of ipsilateral cerebral hemispheres caused by lesions that involve both dopaminergic and noradrenergic systems but not when dopaminergic neurons only are affected. We speculate that the dementia of Parkinson disease may be more prevalent when degeneration of catecholaminergic systems is widespread and not restricted to the dopaminergic system.
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PMID:Abnormalities of cerebral oxidative metabolism in animal models of Parkinson disease. 627 64

A novel mitochondrial DNA transfer RNA mutation at position 5549 was identified in a patient with dementia, chorea, cerebellar ataxia, deafness, and peripheral neuropathy in the absence of clinical myopathy. Muscle biopsy specimens showed ragged red and cytochrome oxidase-negative fibers, and reduced complex I activity on polarography. There was diffuse neuronal loss and gliosis throughout the brain on postmortem examination. The heteroplasmic mutation had a widespread distribution in autopsy tissues.
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PMID:A new mitochondrial DNA mutation associated with progressive dementia and chorea: a clinical, pathological, and molecular genetic study. 769 40

The results of laboratory investigations in concerning 15 patients suspected of mitochondrial disease (MD) are presented. Our purpose is to provide an outline of the investigative modalities that support the clinical suspicion and have been found to be useful in the diagnosis. Five clinical groups were studied including 5 exercise intolerances (2 with inflammatory myopathy), 3 with myopathies (1 with dilated cardiomyopathy), 2 with progressive external oftalmoplegia (1 associated with cerebellar ataxia+epilepsy+hypertrophic cardiomyopathy+pes cavus), 4 with encephalopathies (3 with myoclonic encephalopathies with ataxia and dementia and 1 with epilepsy and tremor), and 1 with metabolic acidosis and cardiomyopathy. We used the following categories of investigative procedures: clinical phenotype analysis including pedigree study, neurophysiological tests, bicycle ergometric evaluation, neuroimaging, microscopic study of skeletal muscle biopsy, post-mortem examination, biochemical assays and molecular genetic studies. EMG showed myopathic changes in 5 cases, features of neuropathy in 2, mixed myopathic and neuropathic pattern in 1 and nonspecific changes in 3. EMG was normal in 3 patients. The most common skeletal muscle abnormalities were variation in fiber size (60%), lipid inclusions (33.3%), oxidative subsarcolemmal aggregates (26.7%) and ragged-red fibers (26.7%). Electron microscopy revealed mitochondrial abnormalities in 8 out of 14 patients' muscle biopsies, and in myocardiac and hepatic tissues of another. Site of biochemical defect was located in 12 patients. Complex I defect in 6, complexes I+IV deficiencies in 3, complex II defect in 1, complex IV deficiency in 1, complexes II+IV deficiencies in 1, and complex III defect in 1. In 2 patients the biochemical defect was not located. Mitochondrial DNA alterations were not found in 7 investigated patients. The clinical spectrum of MD has become increasingly wider. After the clinica suspicion, the diagnosis depends up on the appropriate use of skeletal muscle biopsy, biochemical investigations and molecular genetic techniques. Conventional EMG and automatic measurement of the electromyogram are particularly helpful in confirming the clinical suspicion in patients with predominantly central nervous system disease or in cases in which clinical signs are few.
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PMID:[Clinical and investigative approaches in mitochondrial diseases. A review of 15 cases]. 780 49

Several reports have indicated that point mutations of the mitochondrial DNA (mtDNA) contribute to the pathogenesis of Alzheimer's disease (AD). However, other groups have failed to find similar associations between these mutations and AD. A recent report described a set of mutations in the mtDNA encoded cytochrome oxidase genes which may account for 20% of all AD cases. We screened brain tissue from 65 AD patients for each of these previously reported mtDNA mutations but were unable to find an increased incidence of any of them in our AD sample. However, one patient with a mutation in the APP gene did harbour a novel mtDNA mutation (G to C at position 5705 in the tRNAAsn gene) that might have contributed to the very early onset of dementia in this individual. The role of mtDNA mutations in the pathogenesis of AD remains unclear, but they do not appear to be primary causes but may contribute to the onset of the disease.
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PMID:Mitochondrial DNA mutations in Alzheimer's disease. 942 53

In vivo brain imaging of patients with Alzheimer's disease (AD) using positron emission tomography (PET) demonstrates progressive reductions in resting-state brain glucose metabolism and blood flow in relation to dementia severity, more so in association than primary cortical regions. During cognitive or psychophysical stimulation, blood flow and metabolism in the affected regions can increase to the same extent in mildly demented AD patients as in age-matched controls, suggesting that energy delivery is not rate limiting. Activation declines with dementia severity, and is markedly reduced in severely demented patients. These results suggest that there is an initial "normal" functionally-responsive stage in AD, followed by a late less responsive stage. Studies of biopsied and postmortem brain indicate that the initial stage is accompanied by selective and potentially reversible down-regulation of the brain enzymes, including cytochrome oxidase, which mediate mitochondrial oxidative-phosphorylation.
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PMID:Functional brain imaging in the resting state and during activation in Alzheimer's disease. Implications for disease mechanisms involving oxidative phosphorylation. 1067 35

The effects of EGb 761 on the CNS underlie one of its major therapeutic indications; i.e., individuals suffering from deteriorating cerebral mechanisms related to age-associated impairments of memory, attention and other cognitive functions. EGb 761 is currently used as symptomatic treatment for cerebral insufficiency that occurs during normal ageing or which may be due to degenerative dementia, vascular dementia or mixed forms of both, and for neurosensory disturbances. Depressive symptoms of patients with Alzheimer's disease (AD) and aged non-Alzheimer patients may also respond to treatment with EGb 761 since this extract has an "anti-stress" effect. Basic and clinical studies, conducted both in vitro and in vivo, support these beneficial neuroprotective effects of EGb 761. EGb 761 has several major actions; it enhances cognition, improves blood rheology and tissue metabolism, and opposes the detrimental effects of ischaemia. Several mechanisms of action are useful in explaining how EGb 761 benefits patients with AD and other age-related, neurodegenerative disorders. In animals, EGb 761 possesses antioxidant and free radical-scavenging activities, it reverses age-related losses in brain alpha 1-adrenergic, 5-HT1A and muscarinic receptors, protects against ischaemic neuronal death, preserves the function of the hippocampal mossy fiber system, increases hippocampal high-affinity choline uptake, inhibits the down-regulation of hippocampal glucocorticoid receptors, enhances neuronal plasticity, and counteracts the cognitive deficits that follow stress or traumatic brain injury. Identified chemical constituents of EGb 761 have been associated with certain actions. Both flavonoid and ginkgolide constituents are involved in the free radical-scavenging and antioxidant effects of EGb 761 which decrease tissue levels of reactive oxygen species (ROS) and inhibit membrane lipid peroxidation. Regarding EGb 761-induced regulation of cerebral glucose utilization, bilobalide increases the respiratory control ratio of mitochondria by protecting against uncoupling of oxidative phosphorylation, thereby increasing ATP levels, a result that is supported by the finding that bilobalide increases the expression of the mitochondrial DNA-encoded COX III subunit of cytochrome oxidase. With regard to its "anti-stress" effect, EGb 761 acts via its ginkgolide constituents to decrease the expression of the peripheral benzodiazepine receptor (PBR) of the adrenal cortex.
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PMID:Ginkgo biloba extract (EGb 761) and CNS functions: basic studies and clinical applications. 1147 35

Over 100 mutations of mitochondrial DNA (mtDNA) have been associated with human disease. The phenotypic manifestation of mtDNA mutations is extremely broad, from oligosymptomatic patients with isolated deafness, diabetes, ophthalmoplegia, etc., to complex encephalomyopathic disorders that may include dementia, seizures, ataxia, stroke-like episodes, etc. The genotype variants are also wide, with rearrangements (deletions, duplications) and point mutations affecting protein coding genes, tRNAs and rRNAs. There are some broad genotype/phenotype correlations but also substantial overlap. The pathogenetic mechanisms involved in the expression of mtDNA mutations are still not yet fully understood. More recently, mutations of nuclear genes encoding subunits of the respiratory chain, particularly those of complex I, have been identified. These predominantly, but not exclusively, involve infant onset disease with early death. Recently it has become clear that the function of the respiratory chain may be impaired by mutations affecting other mitochondrial proteins or as a secondary phenomenon to other intracellular biochemical derangements. Examples include Friedreich ataxia where a mutation of a nuclear encoded protein (frataxin), probably involved in iron homeostasis in mitochondria, results in severe deficiency of the respiratory chain in a pattern indicative of free radical mediated damage. Mutations of nuclear encoded proteins involved in cytochrome oxidase assembly and maintenance have been characterised and, as predicted, are associated with severe deficiency of cytochrome oxidase and, most frequently, Leigh syndrome. Defects of intracellular metabolism, with particularly excess-free radical generation including nitric oxide or peroxynitrite, may cause secondary damage to the respiratory chain. This is probably of relevance in Huntington disease, motor neuron disease (amyotrophic lateral sclerosis) and Wilson disease. These disorders seem to have defective oxidative phosphorylation as a common pathway in their pathogenesis and it may be that treatments designed to improve respiratory chain function may ameliorate the progression of these disorders.
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PMID:Primary and secondary defects of the mitochondrial respiratory chain. 1213 29

Three models are described in rats which attempt to mimic morphological and behavioural pathology of Alzheimer's dementia; intracerebroventricular injection of streptozotocin (STZ), permanent bilateral carotid artery occlusion (2VO) and brain mitochondrial cytochrome oxidase inhibition by sodium azide. Learning and memory are impaired within 4 weeks in all models. This probably involves a reduction in cortical and/or hippocampal cholinergic neurotransmission. STZ causes microglial activation and specific damage to myelinated tracts in the fornix through generation of oxidative stress, thereby disrupting connections between the septum and hippocampus. 2VO results in damage to myelin and CA1 cells in hippocampus and in abnormal processing of APP to beta-amyloid. It is not known if microglial activation and neuronal damage occur after sodium azide administration. Memory and learning can be improved in the STZ and 2VO models by estradiol, melatonin and cholinesterase inhibitors. Antioxidants and neuroprotective agents may also decrease memory deficits by preventing inflammation and neurodegeneration.
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PMID:Rat models of dementia based on reductions in regional glucose metabolism, cerebral blood flow and cytochrome oxidase activity. 1499 59


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