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Mitochondrial Respiratory Chain Complexes (mitochondrial + respiratory_chain_complex)
Selected AbstractsClinical characteristics of patients with non-specific and non-categorized mitochondrial diseasesACTA PAEDIATRICA, Issue 11 2009Jeong Tae Kim Abstract Aim:, Mitochondrial disease is a heterogeneous disorder entity induced by defects in mitochondrial respiratory chain complex (MRC). A significant portion of patients with MRC defect will not conform to a specific, known syndrome. We have analysed the clinical features of 108 Korean paediatric patients with non-specific and non-categorized mitochondrial disease. Methods:, We retrospectively reviewed the clinical and laboratory features of 108 paediatrics patients with non-specific and non-categorized mitochondrial diseases who showed defects in MRC activity, confirmed by spectrophotometric biochemical enzyme assay of their muscles. Results:, Neuromuscular involvement was noted in all patients, with developmental delay and seizure accounting for 92.6% and 77.8% of total patients respectively. Various extraneurological symptoms were observed. Most patients exhibited MRC I defect, accounting for 100 (92.6%) patients. The most common brain magnetic resonance imaging (MRI) finding was diffuse cerebral atrophy. However, in 23.1% of patients, no notable changes were visible on MRI. Conclusions:, Mitochondrial respiratory chain complex I defect was the most common finding in this study. Though neuromuscular symptoms predominated, with presence of numerous extraneurological findings, we could not find any novel symptoms that might be unique to this category of mitochondrial disease. But, comparatively, more patients presented with unremarkable birth histories and normal brain MRI findings. [source] Evaluation of renal function in children with mitochondrial respiratory chain complex defect: usefulness of cystatin CACTA PAEDIATRICA, Issue 6 2009Soon Min Lee Abstract Aim: Mitochondrial disorders with respiratory chain complex defect are known to show a broad spectrum of clinical phenotypes, though their contribution to renal disease has not received much attention. The aim of this study was to evaluate renal function using different markers of the glomerular filtration rate (GFR) in children with mitochondrial respiratory chain complex (MRC) defects. Methods: Twenty-two patients with MRC I defect confirmed by biochemical enzyme assays using muscle tissue, were evaluated for renal function with diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy, urine creatinine clearance, serum creatinine (Scr) and cystatin C (Cys C) levels. Results: All patients showed lower levels within normal range of Scr (0.4,0.7 mg/dL, mean 0.47 mg/dL), and with no significant correlation with DTPA,GFR. Cys C showed significant correlation with DTPA,GFR (p < 0.01) providing higher diagnostic accuracy than creatinine in patients with MRC defect. Conclusion: In mitochondrial disorder with MRC defect, Scr could not fully reflect renal function due to the relatively small body mass of patients. Considering the limited clinical availability of DTPA renal scintigraphy, Cys C should be taken as the first step to evaluate GFR in mitochondrial disorders. [source] Decreased activities of mitochondrial respiratory chain complexes in non-mitochondrial respiratory chain diseasesDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2006Joannie Hui MBBS The aim of this study was to illustrate the difficulties in establishing a diagnosis of mitochondrial respiratory chain (MRC) disorders based on clinical grounds in combination with intermediate activities of the MRC enzyme complexes. We reviewed retrospectively all medical and laboratory records of patients initially considered likely to have MRC disorders on clinical grounds, and subsequently diagnosed with other disorders (n=20; 11 males, 9 females). Data were retrieved from hospital records, referral letters, and results of enzymatic analysis at a reference laboratory. Clinical symptoms included developmental delay, epilepsy, hypotonia, movement disorder, spastic quadriplegia, tetany, microcephaly, visual problems, carpopedal spasms, dysmorphism, hearing loss, muscle weakness and rhabdomyolysis, and fulminant hepatitis. Blood and cerebrospinal fluid lactate levels were elevated in 13/20 and 9/20 respectively. One or more MRC complex activities (expressed as ratios relative to citrate synthase and/or complex II activity) were less than 50% of control mean activity in 11/20 patients (including patients with deficiencies of pyruvate dehydrogenase complex, pantothenate kinase, holocarboxylase synthetase, long-chain hydroxy acyl-CoA dehydrogenase, molybdenum co-factor, and neonatal haemochromatosis). One patient had a pattern suggestive of mitochondrial proliferation. We conclude that intermediate results of MRC enzymes should be interpreted with caution and clinicians should be actively looking for other underlying diagnoses. [source] NO message from muscleMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2001Zarko Grozdanovic Abstract The synthesis of the free radical gas nitric oxide (NO) is catalyzed by the enzyme NO synthase (NOS). NOS converts arginine and molecular oxygen to NO and citrulline in a reaction that requires NADPH, FAD, FMN, and tetrahydrobiopterin as cofactors. Three types of NOS have been identified by molecular cloning. The activity of the constitutively expressed neuronal NOS (nNOS) and endothelial NOS (eNOS) is Ca2+/calmodulin-dependent, whereas that the inducible NOS (iNOS) is Ca2+ -insensitive. The predominant NOS isoform in skeletal muscle is nNOS. It is present at the sarcolemma of both extra- and intrafusal muscle fibers. An accentuated accumulation of nNOS is found in the endplate area. This strict sarcolemmal localization of nNOS is due its association with the dystrophin-glycoprotein complex, which is mediated by the syntrophins. The activity of nNOS in skeletal muscle is regulated by developmental, myogenic, and neurogenic influences. NO exerts several distinct effects on various aspects of skeletal muscle function, such as excitation-contraction coupling, mitochondrial energy production, glucose metabolism, and autoregulation of blood flow. Inside the striated muscle fibers, NO interacts directly with several classes of proteins, such as soluble guanylate cyclase, ryanodine receptor, sarcoplasmic reticulum Ca2+ -ATPase, glyceraldehyde-3-phosphate dehydrogenase, and mitochondrial respiratory chain complexes, as well as radical oxygen species. In addition, NO produced and released by contracting muscle fibers diffuses to nearby arterioles where it acts to inhibit reflex sympathetic vasoconstriction. Microsc. Res. Tech. 55:148,153, 2001. © 2001 Wiley-Liss, Inc. [source] Computerized analysis of cytochemical reactions for dehydrogenases and oxygraphic studies as methods to evaluate the function of the mitochondrial sheath in rat spermatozoaANDROLOGIA, Issue 1 2001M. Piasecka Cytochemical reactions for mitochondrial NADH-dependent dehydrogenases (diaphorase/NADH which is related to flavoprotein), NAD-dependent dehydrogenases (isocitrate, malate) and succinate dehydrogenase were carried out in rat spermatozoa. In addition to a morphological evaluation, the intensity of the reactions was assessed using a computer image analysing system (Quantimet 600 S). The intensity of the reactions was examined in sperm midpieces by measuring integrated optical density (IOD) and mean optical density (MOD). The activity of mitochondrial respiratory chain complexes was also analysed using the polarographic method. In the population of spermatozoa studied, all whole spermatozoa midpieces were completely filled with formazans, the product of the cytochemical reaction. These morphological findings corresponded to the values obtained for IOD and MOD for the given enzymes. In the oxygraphic studies, the spermatozoa demonstrated consumption of oxygen in the presence of substrates for I, II and IV complexes and their mitochondria revealed normal integrity and sensitivity to the substrates and inhibitors. However, the oxygraphic studies revealed differences between the sperm and somatic cells. These differences concerned the stimulation of pyruvate oxidation by malate, the lack of an effect of malonic acid on phenazine methosulphate (an acceptor of electrons) oxidation and the lack of an effect of cytochrome c on ascorbate oxidation. The cytochemical method, together with densitometric measurements, enables: (1) the reaction intensity to be determined objectively; (2) subtle and dramatic differences in reaction intensity to be revealed between spermatozoa that do not differ under morphological evaluation of the intensity; (3) possible defects within the mitochondrial sheath to be located and assessed in a large number of spermatozoa. This method can be used as a screening method alongside the routine morphological examination of spermatozoa. On the other hand, the oxygraphic method in the inner membrane of mitochondria can reveal functional changes which are related to the action of respiratory chain complexes and display characteristic features of mitochondria energy metabolism. The methods used are complementary and allow the complex evaluation of mitochondria in spermatozoa. Both methods can be used in experimental and clinical studies. [source] Mitochondrial metabolism in the rat during bladder regeneration induced by small intestinal submucosaBJU INTERNATIONAL, Issue 3 2004Rozbeh Faramarzi-Roques OBJECTIVE To assess mitochondrial metabolism of bladder tissue induced by small-intestinal submucosa (SIS), by comparing the mitochondrial enzyme metabolism in this tissue with that in normal bladder tissue and thus evaluate intracellular normality. MATERIAL AND METHODS In all, 70 rats were grouped into healthy controls (10), surgical controls with a simple bladder incision (15) and rats treated by partial cystectomy with replacement by the SIS graft (45). At 1, 3 and 6 months the rats were killed, the enzymes of mitochondrial respiratory chain complexes assayed, and the respiration of permeabilized bladder fibres assessed using polarographic analysis. RESULTS The enzyme activities of control and treated rats at 3 months were identical. The results from the polarographic analysis of respiration were also similar to that in normal tissue apart from a decrease in the number of mitochondria. Histologically, there was complete regeneration at 6 months. CONCLUSION After a phase of inflammation the bladder regenerates after a patch is placed. The new tissue has the same enzymatic and histological features as normal bladder tissue. [source] A non-syndromic hearing loss caused by very low levels of the mtDNA A3243G mutationACTA NEUROLOGICA SCANDINAVICA, Issue 1 2004M. Mancuso We described a patient with progressive non-syndromic hearing loss (NSHL) harboring the A3243G mutation in the mitochondrial DNA (mtDNA). Muscle biopsy showed scattered ragged-red, cytochrome c oxidase negative fibers, whereas the biochemical analysis of the mitochondrial respiratory chain complexes was normal. Restriction fragment length polymorphism (RFLP) analysis showed A3243G mtDNA transition, present at very low in patient's muscle (3%) and in urinary sediments (1%), and not detectable in blood and buccal mucosa. The patient was submitted to a bilateral cochlear implantation with post-operative excellent hearing and communicative outcomes. Our findings indicate that A3243G mutation may be responsible both for SHL and NSHL, may be depending on the levels of mutated mtDNA. Patients with hearing loss due to mtDNA mutations should be considered as good candidates for cochlear implantation. [source] | ||||||||||