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At least 253 records · Page 14Linked to original sources
PubMed1991

Functional and molecular analysis of mitochondria in thyroid oncocytoma.

We report a functional and molecular analysis of nine oncocytic tumors of the human thyroid. In all the abundance of mitochondria observed ultrastructurally was accompanied by an increase in enzymatic activities of respiratory complexes 1 (NADH dehydrogenase), 11 (succinate dehydrogenase) IV (cytochrome c oxidase), and V (ATPase). Western blot analysis failed to detect uncoupling protein in the tumors. The elevated respiratory enzyme activities were paralleled by an increase in the mitochondrial DNA content. Restriction analysis of mitochondrial DNA gave no indication of heteroplasmy or other gross alterations. We conclude that the mitochondrial proliferation in oncocytic tumors is probably not the result of a compensatory mechanism for the deficiency in enzyme complexes of the mitochondrial respiratory chain.

Adenoma↗
PubMed1984

Inhibition of axoplasmic transport in the developing visual system of the rat: IV. Quantitative Golgi, electron microscopic, and histochemical analyses of the maturation of the visual cortex.

Intraocularly injected colchicine suppresses axonal transport within the developing rat's optic nerve throughout the critical period of visual system development. This results in a stunting of retinofugal terminals and relay neurons in the lateral geniculate nucleus. The present study focuses upon the effects of this unique form of developmental deprivation on the maturation of the visual cortex. Colchicine, in concentrations of from 10(-5) to 10(-2) M, was injected into the eyes of albino rats at birth or at 5, 10, or 15 days of age. Litters were killed at 5 to 50 days after this single injection, and the brains were processed for Nissl, rapid Golgi, histochemical, or electron microscopic analysis. The following results were obtained: Planimetry of coronal sections of the striate cortex revealed a reduction in the thickness of the cortex and in the ratio of neuropil area to neuronal soma area contralateral to the injected eye which was confined principally to layer IV, lower layer III, and upper layer V. This effect was inversely related to postnatal age at injection and directly proportional to colchicine concentration. A rapid Golgi analysis of 51 pairs of layer V pyramidal neurons in control and experimental cortex demonstrated a reduction in the number and size of spines along the portion of the apical dendrite passing through lower layer III and IV following colchicine administration at birth or 5 or 10 days of age but no significant change in the branching pattern of the entire dendritic arbor. Electron microscopy revealed a reduction in the number of small, asymmetric synaptic complexes with the result that the average size of remaining profiles was increased in layers III and IV. Histochemical analysis of cortical succinic dehydrogenase and cytochrome oxidase revealed a distinct band of intense enzyme activity in lower layers III and IV in normal cortex at 20-30 days of age. This band was significantly reduced in intensity after neonatal injection of colchicine as shown by densitometric measurements and comparison of experimental and control cortex. It is concluded that the geniculocortical projection, while not affected directly by colchicine administration, is altered by the secondary effects of axonal transport suppression, leading to an alteration in the establishment of cortical synaptic patterns and arborizations of their postsynaptic neurons whose dendrites are located in those layers recipient to this projection.

Animals↗
PubMed2006

Novel mitochondrial transfer RNA(Phe) gene mutation associated with late-onset neuromuscular disease.

BACKGROUND: An extensive range of molecular defects have been identified in the human mitochondrial genome (mitochondrial DNA); many are associated with well-characterized, progressive neurological syndromes, but a minority of patients have uncharacteristic phenotypes in which symptoms may be relatively mild. OBJECTIVE: To describe a novel transfer RNA(Phe) mutation of mitochondrial DNA in a late-onset case with a mild phenotype of mitochondrial disease. DESIGN: Case report. PATIENT: A 66-year-old woman presented with a 4-year history of walking difficulties due to exercise intolerance and paresthesia in the feet. Clinical examination results were normal. Her deceased mother had similar walking difficulties, but her sister and 2 children were unaffected. RESULTS: The demonstration of a marked histochemical defect in cytochrome c oxidase activity on muscle biopsy prompted molecular investigation of mitochondrial DNA, revealing a novel maternally inherited mutation in the variable loop of the mitochondrial transfer RNA(Phe) gene. This 622G>A transition was heteroplasmic and segregated with cytochrome c oxidase deficiency in single fibers. CONCLUSION: This case serves to illustrate that primary defects of the mitochondrial genome should be considered even in older patients with late-onset, mild neuromuscular symptoms.

Age of Onset↗
PubMed1985

Changes in ultrastructure and function of hypoxic V79 fibroblast cells after treatment with misonidazole.

Morphologic and enzymatic changes due to exposure to the radiosensitizing chemical, misonidazole, have been identified in V79 cells grown in a system in which oxygen tensions and culture density have been controlled. Misonidazole prevented the increase in mitochondrial size normally seen during exposure of these cells to conditions of moderate hypoxia (2 X 10(3) ppm O2). Mitochondrial size was also significantly decreased in cells from exponential cultures exposed to 1 mmol/l misonidazole. Morphologic changes to the mitochondria that varied from data reported elsewhere were also noted. Misonidazole caused a significant initial decrease in cytochrome oxidase activity after 4 hours of exposure of aerobic and moderately hypoxic cultures that did not return to normal in chronically hypoxic cells during continued exposure to the drug.

Animals↗
PubMed2006

Effects of veratrine on skeletal muscle mitochondria: ultrastructural, cytochemical, and morphometrical studies.

The alkaloid veratrine is a lipid-soluble neurotoxin, which target voltage-gated Na+ channels for their primary action. Recently, we showed that this alkaloid may cause myonecrosis and evidences suggest mitochondria as one of its cell targets. Herein, we investigate the effects caused by variable concentration of veratrine (250 and 550 microg/mL) on mitochondrial oxygen consumption, respiratory chain enzymes activities, and ultrastructure, combining electron microscopy with cytochemical and biochemical approaches. The results showed different sort of ultrastructural changes, both in isolated and intramuscular mitochondria. Veratrine decreased mitochondrial nicotinamide adenine dinucleotide dehydrogenase (NADH-d), succinic dehydrogenase (SDH), and cytochrome oxidase (COX) activities, significantly and dose-dependently inhibited the state 3 respiration rate, respiratory control ratio (RCR), and ADP/O on isolated rat skeletal muscle mitochondria, whereas state 4 was unaffected. A tendency of increase in mitochondria diameter was seen with 250 microg/mL veratrine. We conclude that the alkaloid would probably act on mitochondrial membrane phospholipid configuration, which would explain the changes observed.

Animals↗
PubMed1983

Focal deficiency of cytochrome-c-oxidase in skeletal muscle of patients with progressive external ophthalmoplegia. Cytochemical-fine-structural study.

In skeletal muscle biopsies of 8 patients with progressive external ophthalmoplegia combined light and fine structural cytochemical studies of cytochrome-c-oxidase revealed the absence of the enzyme in single fibres with or without accumulation of abnormal mitochondria. However, some fibres showed abnormal mitochondria without any deficiency of the enzyme. In one case with only slight mitochondrial proliferation the existence of the enzyme defect was the most remarkable finding. The occurrence of the enzyme defect obviously does not depend on concomitant structural alterations of the chondriom. The results are consistent with an acquired mitochondrial injury leading to a gradual loss of enzyme activity either earlier (with or without a minimal reactive mitochondrial proliferation) or later (after a phase of mitochondrial proliferation) in the course of the disease. Focal lack of cytochrome-c-oxidase activity is apparently a constant feature of the syndrome; it therefore may be not only of pathogenetic but also of diagnostic importance and in this connection cytochemical-fine-structural demonstration of cytochrome-c-oxidase is a valuable method. In contrast to the biochemical approach it allows not only the detection but also the exact anatomical localization of single fibre defects.

Biopsy↗
PubMed1976

Fusion of phospholipid vesicles reconstituted with cytochrome c oxidase and mitochondrial hydrophobic protein.

Reconstituted cytochrome oxidase liposomes were fused with liposomes reconstituted with mitochondrial hydrophobic protein, which acts as a membrane-bound uncoupler of cytochrome oxidase. Fusion was assayed by the loss of respiratory control of cytochrome oxidase as measured by the increased rate of ascorbate oxidation induced by hydrophobic protein when both proteins shared the same vesicles. Fusion was dependent on the presence of phosphatidylserine in the liposomes Ca++ in the aqueous medium. Phosphatidylcholine-phosphatidylserine liposomes required higher concentrations of phosphatidylserine and Ca++ than did phosphatidylethanolamine-phosphatidylserine liposomes. Cytochrome oxidase vesicles containing high concentrations of phosphatidylserine showed little or no respiratory control, while those with lower concentrations showed high respiratory control; respiratory control could be induced by fusing cytochrome oxidase vesicles containing high phosphatidylserine with protein-free liposomes containing low phosphatidylserine concentration. If cytochrome oxidase vesicles and hydrophobic protein vesicles were prefused separately for 15 min, they lost the ability to fuse upon being subsequently mixed together. The reconstituted vesicles had diameters of about 200 A; fusion yielded vesicles with diameters in excess of 1000 A.

Animals↗
PubMed1988

Mitochondrial oculoskeletal myopathy: case report.

We report a case of oculoskeletal myopathy with abnormal mitochondria in which the chief clinical feature was ophthalmoplegia. Muscle weakness was mild and there were no retinal or cerebellar abnormalities, no deafness and no cardiac defects. The muscle biopsy specimen revealed subsarcolemmal mitochondrial aggregates and ragged red fibers. Electronmicroscopy showed that the aggregates were made up of mitochondria of variable size with structural abnormalities of the cristae and crystalloid inclusions. We believe that this oculoskeletal myopathy is distinct from Kearn-Sayre syndrome.

Adult↗