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

---

Query: EC:1.6.5.3 (complex I)
8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Whether pure thiamine deficiency produces a neuropathy in Mammalia is still debated. Rats were pair-fed-synthetic diets with and without thiamine. When studied histochemically, soleus muscles from thiamine-deficient rats showed (1) small, angular fibers that had high NADH dehydrogenase activities; (2) a loss of 43% of type II (FOG) fibers; (3) decreased intensity of the reaction for betaOHB dehydrogenase; and (4) fibers with subsarcolemmal collections resembling "ragged-red" muscle. Electron microscopy revealed degeneration of some small myelin sheaths of distal and intramuscular nerves; atrophic, degenerating, hypoosmophilic muscle fibers in soleus and vastus medialis; and scattered muscle fibers with abnormal collections of deranged mitochondria accompanied by lipid droplets. These abnormalities, not found in control muscles, indicate that both motor neuropathy and mild mitochondrial changes, such as are seen in the "ragged-red" diseases, are induced by pure thiamine deficiency.
...
PMID:Experimental thiamine deficiency. Neuropathic and mitochondrial changes induced in rat muscle. 5 58

Diagnosis of respiratory chain defects in cultured skin fibroblasts is a difficult diagnostic procedure. We investigated the feasibility of using survival of skin fibroblasts in culture medium with galactose as the major carbon source as a method of quickly diagnosing cell lines that were compromised in oxidative metabolism. We found that cells from patients with most forms of cytochrome oxidase deficiency, cells with complex I deficiency, cells with multiple respiratory chain defects and cells with severe pyruvate dehydrogenase (PDH) complex deficiency failed to survive when subcultured into galactose (5 mM) medium. Cells from patients with Lebers hereditary optic neuropathy (LHON), Kearns-Sayre syndrome (KSS), myoclonus-epilepsy-lactic acidosis-stroke (MELAS), the hepatic form of cytochrome oxidase deficiency, and mild PDH complex deficiency survived well in galactose (5 mM)-containing medium. This could be used as a rapid screening test for skin fibroblasts with major oxidative defects.
...
PMID:Nonviability of cells with oxidative defects in galactose medium: a screening test for affected patient fibroblasts. 132 73

The Tas2 and Vic2 Australian families are affected with a variant of Leber hereditary optic neuropathy (LHON). The risk of developing the optic neuropathy shows strict maternal inheritance, and the ophthalmological changes in affected family members are characteristic of LHON. However, in contrast to the common form of the disease, members of these two families show a high frequency of vision recovery. To ascertain the mitochondrial genetic etiology of the LHON in these families, both (a) the the nucleotide sequences of the seven mitochondrial genes encoding subunits of respiratory-chain complex I and (b) the mitochondrial cytochrome b gene were determined for representatives of both families. Neither family carries any of the previously identified primary mitochondrial LHON mutations: ND4/11778, ND1/3460, or ND1/4160. Instead, both LHON families carry multiple nucleotide changes in the mitochondrial complex I genes, which produce conservative amino acid changes. From the available sequence data, it is inferred that the Vic2 and Tas2 LHON families are phylogenetically related to each other and to a cluster of LHON families in which mutations in the mitochondrial cytochrome b gene have been hypothesized to play a primary etiological role. However, sequencing analysis establishes that the Vic2 and Tas2 LHON families do not carry these cytochrome b mutations. There are two hypotheses to account for the unusual mitochondrial genetic etiology of the LHON in the Tas2 and Vic2 LHON families. One possibility is that there is a primary LHON mutation within the mitochondrial genome but that it is at a site that was not included in the sequencing analyses. Alternatively, the disease in these families may result from the cumulative effects of multiple secondary LHON mutations that have less severe phenotypic consequences.
...
PMID:A variant of Leber hereditary optic neuropathy characterized by recovery of vision and by an unusual mitochondrial genetic etiology. 146 7

We investigated a family with Leber's hereditary optic neuropathy in which affected individuals were homoplasmic for the point mutation of the NADH-dehydrogenase 4 gene of mitochondrial DNA, described by Wallace and colleagues in 1988. The proband had bilateral optic atrophy, tremor, dystonia, and sharply defined lesions in the putamen on magnetic resonance images. Optic atrophy was found in another 3 of 13 investigated relatives on the maternal side. Additional neurological signs were found but only in patients with optic neuropathy. The morphological appearance and the respiratory chain function of muscle tissue were investigated in the proband, his mother, and 3 siblings. Polarographic measurements revealed complex I deficiency in the 5 investigated subjects. Morphological changes of mitochondria were found in 4 of these subjects. There was no decrease in complex I activity measured as NADH ferricyanide reductase or rotenone-sensitive NADH cytochrome c reductase activities. In other cases with complex I deficiency, good agreement between polarographic and spectrophotometric measurements was found. This study showed that there is decreased activity of complex I of the respiratory chain in muscle and that cerebral striatal lesions occur in Leber's hereditary optic neuropathy with the NADH-dehydrogenase 4 gene point mutation.
...
PMID:Leber's hereditary optic neuropathy and complex I deficiency in muscle. 176 94

We describe a 6-year-old boy who presented with progressive muscle weakness. Additional investigations revealed the existence of a myopathy and a pure motor neuropathy. Biochemical studies in muscle tissue showed a defect of NADH dehydrogenase (complex I). The patient dramatically improved on treatment with riboflavin and L-carnitine. Seven months after the start of the treatment, complex I activity was determined again and appeared to be normalized. Normalization of the enzymatic defect at this level has not been reported before. We provide a survey of nine patients with pure myopathy, associated with complex I deficiency and onset of symptoms in childhood.
...
PMID:Successful treatment of pure myopathy, associated with complex I deficiency, with riboflavin and carnitine. 133 58

Mitochondrial dysfunctions of the muscle in diabetic amyotrophy and of the liver in diabetic fatty liver have been reported. We investigated mitochondrial gene mutations in three cases: (1) a patient with diabetic amyotrophy in the muscles of the lower extremities, and neuropathy; (2) 5 diabetics with myoatrophy, diabetic nephropathy, and chronic renal failure; and (3) an IDDM patient with a diabetic fatty liver. We identified a 5778-bp deletion (8214-13991) in mitochondrial DNA from the muscle and liver biopsy specimens by the primer shift PCR and PCR-direct sequence methods. It is speculated that 5778-bp deletion is due to homogeneous recombination in the 7-bp repeat sequence of TCCTAGA flanking the region deleted in the mitochondrial DNA. Determination of respiratory chain enzyme activities in fresh muscle mitochondria demonstrated the defect in complex I activity. The deletion covers areas coding ND3, ND4, ND4L, and ND5 in complex I. The 5778-bp deletion might cause a defect in mitochondrial oxidative phosphorylation and contribute to the pathogenesis of diabetic amyotrophy, myoatrophy with diabetic nephropathy, and chronic renal failure, as well as diabetic fatty liver in IDDM.
...
PMID:A new mitochondrial DNA deletion associated with diabetic amyotrophy, diabetic myoatrophy and diabetic fatty liver. 760 16

We studied the clinical, biochemical, and genetic features of eight patients with the autosomal recessive mitochondrial syndrome mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). MNGIE is clinically characterized by ophthalmoparesis, peripheral neuropathy, leukoencephalopathy, gastrointestinal symptoms (recurrent nausea, vomiting, or diarrhea) with intestinal dysmotility, and histologically abnormal mitochondria in muscle. Brain MRI scans were consistent with leukodystrophy in seven patients examined. Nerve conduction and EMG studies were compatible with a sensorimotor neuropathy; quantitative EMG of two patients suggested a myogenic process. Muscle mitochondrial enzyme analysis revealed a partial defect of cytochrome c oxidase activity in five patients; three had additional respiratory chain enzyme defects. Two patients had isolated complex I defects, and one had normal respiratory chain function. Southern blot analysis revealed multiple deletions of mitochondrial DNA in four of eight patients.
...
PMID:Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): clinical, biochemical, and genetic features of an autosomal recessive mitochondrial disorder. 816 33

A rare form of Leber hereditary optic neuropathy (LHON) that is associated with hereditary spastic dystonia has been studied in a large Dutch family. Neuropathy and ophthalmological lesions were present together in some family members, whereas only one type of abnormality was found in others. mtDNA mutations previously reported in LHON were not present. Sequence analysis of the protein-coding mitochondrial genes revealed two previously unreported mtDNA mutations. A heteroplasmic A-->G transition at nucleotide position 11696 in the ND4 gene resulted in the substitution of an isoleucine for valine at amino acid position 312. A second mutation, a homoplasmic T-->A transition at nucleotide position 14596 in the ND6 gene, resulted in the substitution of a methionine for the isoleucine at amino acid residue 26. Biochemical analysis of a muscle biopsy revealed a severe complex I deficiency, providing a link between these unique mtDNA mutations and this rare, complex phenotype including Leber optic neuropathy.
...
PMID:Genetic and biochemical impairment of mitochondrial complex I activity in a family with Leber hereditary optic neuropathy and hereditary spastic dystonia. 864 32

Mitochondrial DNA from two genetically unrelated patients carrying the mutation at position 11778 that causes Leber's hereditary optic neuropathy has been transferred with mitochondria into human mtDNA-less rho0206 cells. As analyzed in several transmitochondrial cell lines thus obtained, the mutation, which is in the gene encoding subunit ND4 of the respiratory chain NADH dehydrogenase (ND), did not affect the synthesis, size, or stability of ND4, nor its incorporation into the enzyme complex. However, NADH dehydrogenase-dependent respiration, as measured in digitonin-permeabilized cells, was specifically decreased by approximately 40% in cells carrying the mutation. This decrease, which was significant at the 99.99% confidence level, was correlated with a significantly reduced ability of the mutant cells to grow in a medium containing galactose instead of glucose, indicating a clear impairment in their oxidative phosphorylation capacity. On the contrary, no decrease in rotenone-sensitive NADH dehydrogenase activity, using a water-soluble ubiquinone analogue as electron acceptor, was detected in disrupted mitochondrial membranes. This is the first cellular model exhibiting in a foreign nuclear background mitochondrial DNA-linked biochemical defects underlying the optic neuropathy phenotype.
...
PMID:Respiration and growth defects in transmitochondrial cell lines carrying the 11778 mutation associated with Leber's hereditary optic neuropathy. 866 57

Rapid progress has been made in the identification of mitochondrial DNA mutations which are typically associated with diseases of the nervous system and muscle. The well established mitochondrial disorders are maternally inherited and males and females are equally affected. An exception is Leber's hereditary optic atrophy (LHON) which is observed much more frequently in males than in females. There are three common point mutations in LHON which can be homoplasmic or heteroplasmic. In mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) most mutations are single base changes and lie within the tRNA-Leu gene. Point mutations in myoclonic epilepsy with ragged red fibres (MERRF) usually occur within the tRNA-Lys gene but mutations of the tRNA-Leu gene are also observed. MELAS and MERRF mutations are heteroplasmic and there is considerable clinical overlap between these diseases. Point mutations within the ATPase6 gene result in either neuropathy, ataxia and retinitis pigmentosa (NARP) or in Leigh's syndrome. The latter occurs if the mutation is present in the majority of mitochondria (extreme heteroplasmy). Finally, mitochondrial DNA deletions are the cause underlying Kearns-Sayre syndrome (KSS). Apart from the well-established mitochondrial diseases, there is increasing evidence that mitochondrial mutations may also play a role in the neurodegenerative disorders Parkinson, Alzheimer and Huntington disease. The complex I defect found in Parkinson disease is especially interesting in this respect. However, no causative mitochondrial mutation has as yet been established in any of these three common disorders.
...
PMID:Recent developments in the molecular genetics of mitochondrial disorders. 951 82


1 2 3 4 5 Next >>

---