Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “mitochondrial dysfunction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

Biochemical and morphological changes in myocardium during coronary occlusion and reperfusion in canine hearts: effects of propranolol on myocardial damage.

To clarify the mechanism of irreversible myocardial damage, we studied the relationship between ischaemic mitochondrial dysfunction and leakage of lysosomal enzymes, and the effects of propranolol on myocardial damage. Open chest anaesthetised dogs were divided into six groups: 30 min occlusion of the left anterior coronary artery (LAD); 2 h LAD occlusion; 2 h LAD occlusion after premedication with 0.3 mg.kg-1 propranolol; 30 min LAD occlusion/l h reperfusion; 2 h LAD occlusion/l h reperfusion; and 2 h LAD occlusion/l h reperfusion after propranolol premedication. After occlusion or reperfusion, heart mitochondria were prepared from normal and occluded or reperfused areas, and mitochondrial function (rate of oxygen consumption in State III, and respiratory control index) was measured polarographically. Myocardial tissue was fractionated and activities of lysosomal enzymes (N-acetyl-beta-glucosaminidase and beta-glucuronidase) were measured. Electron microscopic studies were performed. Thirty min occlusion induced mitochondrial dysfunction without leakage of lysosomal enzymes. Reperfusion for 1 h reversed these changes. However occlusion for 2 h induced mitochondrial dysfunction associated with the leakage of lysosomal enzymes, and mitochondrial dysfunction was not reversed by 1 h reperfusion. Propranolol reduced mitochondrial dysfunction after 2 h occlusion and prevented leakage of lysosomal enzymes. Mitochondrial function was fairly well maintained after 1 h reperfusion in dogs premedicated with propranolol. Structural changes in mitochondria were observed in the 2 h occlusion/l h reperfusion group, and were reduced by premedication with propranolol. These results suggest that irreversible injury of ischaemic mitochondria is closely linked with instability of lysosomal membranes, and that propranolol prevented irreversible myocardial mitochondrial dysfunction.

Animals↗

Genetic Landscape and Mitochondrial Metabolic Dysregulation in Patients Suffering From Severe Long COVID.

Long COVID represents a significant global health challenge with an unclear etiology. Alongside accumulating evidence of mitochondrial dysfunction in patients with acute SARS-CoV-2 infection, a symptomatic overlap exists between long COVID and mitochondrial disorders. However, the genetic underpinnings of mitochondrial dysfunction in long COVID have not been previously explored. We employed whole genome sequencing to analyze 13 patients with severe long COVID to identify genetic defects related to mitochondrial function. We performed extracellular bioenergetics flux analysis on peripheral blood mononuclear cells and proteomics to evaluate cellular bioenergetics and compared the results to those of healthy controls. Our investigation identified 10 variants classified as pathogenic or likely pathogenic and 83 variants of unknown significance affecting a wide range of mitochondria-associated biological functions. Bioenergetics flux analysis in peripheral blood mononuclear cells revealed an altered ATP production rate in four long COVID patients compared to healthy controls. This study presents initial evidence of a potential underlying genetic predisposition to mitochondrial dysfunction in long COVID while demonstrating altered cellular energy capacity in a subset of these patients. These findings open avenues for further research into the role of mitochondrial dysfunction and pathology in patients suffering from long COVID and may pave the way for targeted therapeutic strategies aimed at mitigating mitochondrial dysfunction.

Humans↗

Overproduction of Cu/Zn-superoxide dismutase or Bcl-2 prevents the brain mitochondrial respiratory dysfunction induced by glutathione depletion.

Recent work has focused attention on the role of oxidative stress in various acute and chronic neurodegenerative diseases. Low concentrations of the powerful antioxidant glutathione (GSH) and impaired brain energy metabolism, particularly in the substantia nigra, are key features of Parkinson's disease (PD). The main goal of this study was to better characterize the deleterious effects of brain GSH depletion on mitochondrial function. We depleted GSH in the brains of newborn wild-type (WT) and transgenic (Tg) mice overproducing either human Cu/Zn-superoxide dismutase (h-CuZnSOD) or human Bcl2 (h-Bcl-2), by subcutaneous injection of l-buthionine sulfoximine (BSO), a specific inhibitor of gamma-glutamylcysteine synthetase. GSH was 97% depleted in brain homogenates and 90% depleted in brain mitochondria for both WT and Tg mice. This depletion of brain GSH led to a decrease in the activity of the GSH-dependent antioxidant enzyme glutathione peroxidase, both in WT and in Tg animals. BSO treatment decreased the activities of respiratory complexes I, II, and IV in the brain homogenates of WT mice. BSO-treated h-CuZnSOD or h-Bcl-2 Tg mice had no respiratory chain deficiencies. Thus, brain GSH depletion leads to the impairment of mitochondrial respiratory chain activity. The protection of mitochondrial respiratory function by overproduction of Bcl-2 may result from a decrease in the generation of reactive oxygen species (ROS) or lipid peroxidation. The protection of mitochondria by overproduction of CuZnSOD is consistent with the involvement of superoxide or superoxide-derived ROS in the mitochondrial dysfunction caused by brain GSH depletion. This study demonstrates that the antioxidant balance is critical for maintenance of brain mitochondrial function, and its disruption may contribute to the pathogenesis of PD.

Animals↗

Revolution in mitochondrial medicine.

A revolution in chemical pathology occurred about 40 years ago with the discovery of a patient with mitochondrial dysfunction. The field of mitochondrial medicine has experienced explosive growth during the last decade. More than 50 mtDNA mutations and several nuclear gene mutations have been identified in affected patients. The recent development of animal models will continue the revolution in mitochondrial medicine by facilitating in depth studies of the molecular pathogenesis and development of novel drug and gene therapy strategies for mitochondrial dysfunction. As we enter the next millennium, we can expect mitochondrial medicine to remain a dynamic and rapidly developing field.

Aging↗

[Mitochondrial tRNA(leu(UUR)) gene mutation and the decreased activity of cytochrome C oxidase in preeclampsia].

OBJECTIVE: To study the effect of mitochondrial tRNA(leu(UUR)) gene mutation at nuecleotide 3243 and the activity of cytochrome C oxidase on the pathogenesis of pregnancy induced hypertension(PIH). METHODS: 57 cases of PIH and 60 normal pregnancy women were detected of tRNA(leu(UUR)) nt3243A-->G mutation with the method of polymerase chain reaction (PCR) and restriction fragment length polymorphism. Cytochrome C oxidase activity was measured by the rate of cyanide-sensitive oxidation of reduced cytochrome C using luminosity photographer. RESULTS: Cytochrome C oxidase activity was significantly lower in the PIH group than that of controls. The mitochondrial DNA mutation at position 3243 was not found in any of the cases. CONCLUSION: These results suggested that the decreased activity of cytochrome C oxidase might impair the energy production, leading to the mitochondrial dysfunction and placental dysfunction in PIH patients. Mitochondrial dysfunction may be involved in the pathogenesis of preeclampsia. The particular mutation of mitochondrial DNA may not be the common contributor of PIH.

Adult↗

Detection of mitochondrial respiratory dysfunction in circulating lymphocytes using resazurin.

CONTEXT: Laboratory methods currently available for detecting mitochondrial respiratory dysfunction are labor-intensive, require large amounts of isolated mitochondrial protein, invasive (require a skeletal muscle biopsy), and usually produce conflicting results. OBJECTIVE: To develop a rapid, reliable, and noninvasive method for detecting oxidative phosphorylation activity without the need to isolate mitochondrial fractions. DESIGN: Lymphocytes from 6 patients with mitochondrial disorders (3 with mitochondrial myopathy and 3 with Leber hereditary optic neuropathy) and 51 normal control subjects were incubated with 6 microM resazurin without and with mitochondrial inhibition by amiodarone (200 microM), and the fluorescence intensity resulting from resazurin reduction was monitored spectrofluorometrically over time. Mitochondrial respiratory activity was calculated as the difference between uninhibited and inhibited measurements. RESULTS: Mitochondrial respiratory activity was established for 51 normal control subjects and was decreased in all 6 patients with mitochondrial syndromes. Mitochondrial respiratory activity values for patients 1 through 6 compared to the control group after 240 minutes' incubation with resazurin were 55%, 71%, 49%, 61%, 68%, and 59%, respectively (mean mitochondrial respiratory activity of patients, 13.6% or 60.5% of control mean; P < .001). CONCLUSION: This resazurin-based technique proved to be a fast and reproducible method for quantifying mitochondrial activity and identifying respiratory functional defects in patients with mitochondrial disorders.

Adolescent↗

Cell membrane permeability and mitochondrial dysfunction-inducing activities in cell-free supernatants from Serpulina hyodysenteriae serotypes 1 and 2.

Membrane permeability (MP) and mitochondrial dysfunction-inducing (MDI) activities were detected in cell-free supernatants (CFS) of Serpulina hyodysenteriae, using either hemoglobin release from porcine red blood cells (RBC) or cytoplasmic lactate dehydrogenase release from porcine peripheral blood lymphocytes (PBL), and reduction of the 3-(4,5-dimethylthiazoyl-2-y1)-2,5-diphenyltetrazolium bromide dye by porcine PBL. The MP and MDI activities of CFS correlated with each other for serotype 1 and 2 isolates taken at different population densities; however, the kinetics of toxin production varied between each serotype. The loss of enteropathogenicity of two field isolates with nonpathogenic phenotypes and pathogenic isolates passaged up to 45 times in vitro was not attributable to a loss of either membrane permeability or mitochondrial dysfunction-inducing activity of cell-free supernatants. Results from this study suggested the potential for two separate toxins being involved in the pathogenesis of swine dysentery, with the MDI activity correlating with age susceptibility to clinical disease.

Age Factors↗

Adriamycin induced myocardial failure in rats: protective role of Centella asiatica.

Generation of reactive oxygen species and mitochondrial dysfunction has been implicated in adriamycin induced cardiotoxicity. Mitochondrial dysfunction is characterized by the accumulation of oxidized lipids, proteins and DNA, leading to disorganization of mitochondrial structure and systolic failure. The present study was aimed to evaluate the efficacy of Centella asiatica on the mitochondrial enzymes; mitochondrial antioxidant status in adriamycin induced myocardial injury. Adriamycin (2.5 mg/kg body wt., i.p.) induced mitochondrial damage in rats was assessed in terms of decreased activities (p<0.05) of cardiac marker enzymes (lactate dehydrogenase, creatine phosphokinase, amino transferases), TCA cycle enzymes (isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, malate dehydrogenase, respiratory marker enzymes (NADH-dehydrogenase, cytochrome-C-oxidase), mitochondrial antioxidant enzymes (GPx, GSH, SOD,CAT) and increased (p<0.05) level of lipid peroxidation. Mitochondrial damage was confirmed by transmission electron microscopic examination. Pre-co-treatment with aqueous extract of Centella asiatica (200 mg/kg body wt, oral) effectively counteracted the alterations in mitochondrial enzymes and mitochondrial defense system. In addition, transmission electron microscopy study confirms the restoration of cellular normalcy and accredits the cytoprotective role of Centella asiatica against adriamycin induced myocardial injury. Our results demonstrated elevated oxidative stress and mitochondrial dysfunction in adriamycin treated rats. Moreover, on the basis of our findings it may be concluded that the aqueous extract of C. asiatica not only possesses antioxidant properties but it may also reduce the extent of mitochondrial damage.

Animals↗

Loss of function mutations in the gene encoding Omi/HtrA2 in Parkinson's disease.

Recently targeted disruption of Omi/HtrA2 has been found to cause neurodegeneration and a parkinsonian phenotype in mice. Using a candidate gene approach, we performed a mutation screening of the Omi/HtrA2 gene in German Parkinson's disease (PD) patients. In four patients, we identified a novel heterozygous G399S mutation, which was absent in healthy controls. Moreover, we identified a novel A141S polymorphism that was associated with PD (P<0.05). Both mutations resulted in defective activation of the protease activity of Omi/HtrA2. Immunohistochemistry and functional analysis in stably transfected cells revealed that S399 mutant Omi/HtrA2 and to a lesser extent, the risk allele of the A141S polymorphism induced mitochondrial dysfunction associated with altered mitochondrial morphology. Cells overexpressing S399 mutant Omi/HtrA2 were more susceptible to stress-induced cell death than wild-type. On the basis of functional genomics, our results provide a novel link between mitochondrial dysfunction and neurodegeneration in PD.

Amino Acid Sequence↗

Elevated plasma deoxyuridine in patients with thymidine phosphorylase deficiency.

Mutations in the nuclear gene encoding thymidine phosphorylase (TP) cause mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), an autosomal recessive disease with mitochondrial dysfunction and mitochondrial DNA abnormalities. We have demonstrated alterations of thymidine (dThd) metabolism in MNGIE patients. Here, we report the accumulation of another substrate of TP, deoxyuridine (dUrd), whose circulating levels ranged from 5.5 to 24.4 microM (average 14.2) in MNGIE and were undetectable (<0.05 microM) in both TP mutation carriers and controls. The dramatic accumulation of dUrd may contribute to nucleotide pool imbalances and, together with the increased levels of dThd, is likely to contribute to the pathogenesis of MNGIE.

Base Sequence↗

Early release of cytochrome C and activation of caspase-3 in hyperglycemic rats subjected to transient forebrain ischemia.

The mechanisms underlying the aggravating effect of hyperglycemia on brain damage are still elusive. The present study was designed to test our hypothesis that hyperglycemia-mediated damage is caused by mitochondrial dysfunction with mitochondrial release of cytochrome c (cyt c) to the cytoplasm, which leads to activation of caspase-3, the executioner of cell death. We induced 15 min of forebrain ischemia, followed by 0.5, 1, and 3 h of recirculation in sham, normoglycemic and hyperglycemic rats. Release of cyt c was observed in the neocortex and CA3 in hyperglycemic rats after only 0.5 h of reperfusion, when no obvious neuronal damage was observed. The release of cyt c persisted after 1 and 3 h of reperfusion. Activation of caspase-3 was observed after 1 and 3 h of recovery in hyperglycemic animals. No cyt c release or caspase-3 activation was observed in sham-operated controls while a mild increase of cyt c was observed in normoglycemic ischemic animals after 1 and 3 h of reperfusion. The findings that there is caspase activation and cyt c relocation support a notion that the biochemical changes that constitute programmed cell death occur after ischemia and contribute, at least in part, to hyperglycemia-aggravated ischemic neuronal death.

Animals↗

Normalization of cytochrome-c oxidase activity in the rat brain by neuroleptics after chronic treatment with PCP or methamphetamine.

Previous studies, primarily involving the use of positron emission tomography (PET), have contributed to the hypothesis that a state of hypometabolism may underlie schizophrenia. The chronic use of methamphetamine (MAP) or phencyclidine (PCP), both of which have been shown to enhance dopaminergic function in the brain, leads to a psychotic state in man which has prompted the suggestion that these compounds may have utility as models of schizophrenia. In the present study, regional alterations in energy metabolism were examined in the rat brain using cytochrome-c oxidase (COX) and succinate dehydrogenase (SDH) histochemistry following chronic treatment with PCP and MAP. PCP and MAP were administered alone or in the presence of fluphenazine or clozapine to animals for 28 days, after which mitochondrial enzyme activities were estimated. Both PCP and MAP produced profoundly similar decreases in COX activity in a broad spectrum of regions. Most prominent in this regard were the caudate-putamen, nucleus accumbens and septum. No changes were noted in sections stained for SDH activity, suggesting that results were dependent upon neither a generalized mitochondrial dysfunction nor mitochondrial loss. Cell counts and TUNEL histochemistry also failed to reveal any significant differences between control and treated animals, implying that reductions were not a result of cell loss. Both clozapine and fluphenazine offered varying degrees of protection from the effects of PCP and MAP. The results provide evidence which implicates dopaminergic hyperactivity in the finding of reduced energy metabolism in the brains of schizophrenics.

Animals↗

Cerebral energy metabolism in hepatic encephalopathy and hyperammonemia.

Hepatic encephalopathy (HE) is an important cause of morbidity and mortality in patients with severe liver disease. Although the molecular basis for the neurological disorder in HE remains elusive, elevated ammonia and its chief metabolite glutamine are believed to be important factors responsible for altered cerebral functions, including multiple neurotransmitter system(s) failure, altered bioenergetics, and more recently oxidative stress. Accumulated evidence suggests that direct interference of ammonia at several points in cerebral energy metabolism, including glycolysis, TCA cycle, and the electron transport chain, could lead to energy depletion. Additionally, recent studies from our laboratory have invoked the possibility that ammonia and glutamine may induce the mitochondrial permeability transition in astrocytes, a process capable of causing mitochondrial dysfunction. Altered mitochondrial metabolism appears to be an important mechanism responsible for the cerebral abnormalities associated with HE and other hyperammonemic states.

Brain↗

Trichostatin A induces apoptosis in lung cancer cells via simultaneous activation of the death receptor-mediated and mitochondrial pathway?

Trichostatin A (TSA), originally developed as an antifungal agent, is one of potent histone deacetylase (HDAC) inhibitors, which are known to cause growth arrest and apoptosis induction of transformed cells, including urinary bladder, breast, prostate, ovary, and colon cancers. However, the effect of HDAC inhibitors on human non-small cell lung cancer cells is not clearly known yet. Herein, we demonstrated that treatment of TSA resulted in a significant decrease of the viability of H157 cells in a dose-dependent manner, which was revealed as apoptosis accompanying with nuclear fragmentation and an increase in sub-G0/G1 fraction. In addition, it induced the expression of Fas/FasL, which further triggered the activation of caspase-8. Catalytic activation of caspase-9 and decreased expression of anti-apoptotic Bcl-2 and Bcl-XL proteins were observed in TSA-treated cells. Catalytic activation of caspase-3 by TSA was further confirmed by cleavage of pro-caspase-3 and intracellular substrates, including poly (ADP-ribose) polymerase (PARP) and inhibitor of caspase-activated deoxyribonuclease (ICAD). In addition, a characteristic phenomenon of mitochondrial dysfunction, including mitochondrial membrane potential transition and release of mitochondrial cytochrome c into the cytosol was apparent in TSA-treated cells. Taken together, our data indicate that inhibition of HDAC by TSA induces the apoptosis of H157 cells through signaling cascade of Fas/FasL-mediated extrinsic and mitochondria-mediated intrinsic caspases pathway.

Acetylation↗

Ian4 is required for mitochondrial integrity and T cell survival.

Apoptosis is a regulated cell death program controlled by extrinsic and intrinsic signaling pathways. The intrinsic pathway involves stress signals that activate pro-apoptotic members of the Bcl-2 family, inducing permeabilization of mitochondria and release of apoptogenic factors. These proteins localize to the outer mitochondrial membrane. Ian4, a mitochondrial outer membrane protein with GTP-binding activity, is normally present in thymocytes, T cells, and B cells. We and others have recently discovered that a mutation in the rat Ian4 gene results in severe T cell lymphopenia that is associated with the expression of autoimmune diabetes. The mechanism by which Ian4 controls T cell homeostasis is unknown. Here we show that the absence of Ian4 in T cells causes mitochondrial dysfunction, increased mitochondrial levels of stress-inducible chaperonins and a leucine-rich protein, and T cell-specific spontaneous apoptosis. T cell activation and caspase 8 inhibition both prevented apoptosis, whereas transfection of T cells with Ian4-specific small interfering RNA recapitulated the apoptotic phenotype. The findings establish Ian4 as a tissue-specific regulator of mitochondrial integrity.

Animals↗

A Bcr/Abl-independent, Lyn-dependent form of imatinib mesylate (STI-571) resistance is associated with altered expression of Bcl-2.

The relationship between the Src kinase Lyn and Bcl-2 expression was examined in chronic myelogenous leukemia cells (K562 and LAMA84) displaying a Bcr/Abl-independent form of imatinib mesylate resistance. K562-R and LAMA-R cells that were markedly resistant to induction of mitochondrial dysfunction (e.g. loss of mitochondrial membrane potential, Bax translocation, cytochrome c, and apoptosis-inducing factor release) and apoptosis by imatinib mesylate exhibited a pronounced reduction in expression of Bcr/Abl, Bcl-x(L), and STAT5 but a striking increase in levels of activated Lyn. Whereas basal expression of Bcl-2 protein was very low in parental cells, imatinib-resistant cells displayed a marked increase in Bcl-2 mRNA and/or protein levels. Treatment of LAMA-R cells with the Src kinase inhibitor PP2 significantly reduced Lyn activation as well as Bcl-2 mRNA and protein levels. Transient or stable transfection of LAMA84 or K562 cells with a constitutively active Lyn (Y508F), but not with a kinase-dead mutant (K275D), significantly increased Bcl-2 protein expression and protected cells from lethality of imatinib mesylate. Ectopic expression of Bcl-2 protected K562 and LAMA84 cells from imatinib mesylate- and PP2-mediated lethality. Conversely, interference with Bcl-2 function by co-administration of the small molecule Bcl-2 inhibitor HA14-1 or down-regulation of Bcl-2 expression by small interfering RNA or antisense strategies significantly increased mitochondrial dysfunction and apoptosis induced by imatinib mesylate and the topoisomerase inhibitor VP-16 in LAMA-R cells. In marked contrast, these interventions had little effect in parental LAMA84 cells that display low basal levels of Bcl-2. Together, these findings indicate that activation of Lyn in leukemia cells displaying a Bcr/Abl-independent form of imatinib mesylate resistance plays a functional role in Bcl-2 up-regulation and provide a theoretical basis for the development of therapeutic strategies targeting Bcl-2 in such a setting.

Apoptosis↗

Hypothalamic digoxin, cerebral chemical dominance and myalgic encephalomyelitis.

The isoprenoid pathway was assessed in 15 patients with chronic fatigue syndrome. The pathway was also assessed in individuals with differing hemispheric dominance to assess whether hemispheric dominance had any correlation with these disease states. The isoprenoid metabolites--digoxin, dolichol, and ubiquinone--RBC membrane Na+-K+ ATPase activity, serum magnesium and tyrosine/tryptophan catabolic patterns were assessed. The free-radical metabolism, glycoconjugate metabolism, and RBC membrane composition was also assessed. Membrane Na+-K+ ATPase activity and serum magnesium levels were decreased while HMG CoA reductase activity and serum digoxin levels were increased in myalgic encephalomyelitis (ME). There were increased levels of tryptophan catabolites--nicotine, strychnine, quinolinic acid, and serotonin--and decreased levels of tyrosine catabolites--dopamine, noradrenaline, and morphine in ME. There was an increase in dolichol levels, carbohydrate residues of glycoproteins, glycolipids, total/individual GAG fractions, and lysosomal enzymes in ME. Reduced levels of ubiquinone, reduced glutathione, and free-radical scavenging enzymes, as well as increased lipid peroxidation products and nitric oxide, were noticed in ME. The biochemical patterns in ME correlated with those obtained in right hemi spheric chemical dominance. The role of hypothalamic digoxin and neurotransmitter induced immune activation, altered glycoconjugate metabolism, and resultant defective viral antigen presentation, NMDA excitotoxicity and cognitive dysfunction, and mitochondrial dysfunction related myalgia in the pathogenesis of ME is stressed. ME occurs in individuals with right hemispheric chemical dominance.

Adult↗

Acute cigarette smoke exposure induces apoptosis of alveolar macrophages.

Alveolar macrophages (AMs) may play a critical role in cigarette smoke (CS)-related pulmonary diseases. This study was designed to determine whether CS induces apoptosis of AMs. In in vitro studies, mouse, rat, and human AMs and human blood monocyte-derived macrophages cultured with aqueous whole CS extracts underwent apoptosis that was detected by light and electron microscopy and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. The gas phase of CSE did not cause apoptosis. The CS-induced apoptosis was associated with increased oxidative stress, Bax protein accumulation, mitochondrial dysfunction, and mitochondrial cytochrome c release but was independent of p53, Fas, and caspase activation. This apoptosis was inhibited by antioxidants such as glutathione, ascorbic acid, and alpha-tocopherol. In in vivo studies where rats were exposed to the smoke from 10 cigarettes over 5 h in an exposure chamber, approximately 3% of AMs obtained by bronchoalveolar lavage after 24 h showed apoptosis. These results suggest that acute CS exposure is capable of inducing apoptosis of AMs.

Acute Disease↗