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PubMed1976

Cardiac abnormalities in chronic progressive external ophthalmoplegia.

This report describes heart disease in a 32-year-old man with the syndrome of chronic progressive external ophthalmoplegia (CPEO). The surface electrocardiogram showed first degree AV block and left bundle-branch block and there was HV prolongation on the His bundle electrogram. Endomyocardial biopsy showed the changes of hypertrophy on light microscopy, and on electron microscopy there were increased numbers of mitochondria which appeared structurally normal. A permanent demand pacemaker was inserted because these patients are prone to develop complete heart block.

Adult↗
PubMed1989

Endocrine involvement in mitochondrial encephalomyopathy with partial cytochrome c oxidase deficiency.

A 19-year-old man born with thyroprivic hypothyroidism, due to congenital development defect, manifested hypogonadism, stunted growth, chronic progressive external ophthalmoplegia (CPEO), diffuse muscle weakness and wasting, right bundle branch block, cerebral atrophy. Muscle biopsy showed mitochondrial abnormalities. Biochemical investigations on muscle disclosed partial (50%) cytochrome c oxidase deficiency, 58% decrease of cytochrome aa3 and 41% decrease of cytochrome b. Enzyme-linked immunosorbent assay showed decrease of the immunologically active enzyme protein.

Adult↗
PubMed1997

Measurement of tissue oxygen consumption in patients with mitochondrial myopathy by noninvasive tissue oximetry.

We measured oxygen consumption in the exercising lower limb by using noninvasive tissue oximetry with the near-infrared spectra of hemoglobin in the quadriceps muscle during bicycle ergometer exercise in four normal controls and three patients with chronic progressive external ophthalmoplegia (CPEO) as well as one patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Normal controls showed constant oxygenation during exercise and a rapid recovery after exercise. However, all four patients with mitochondrial myopathy showed abnormal oxygenation during exercise and a slow recovery afterward. The results reflected the defect in oxidative phosphorylation and the impairment in oxygen utilization in those patients. The distinctive patterns of imbalance between oxygen delivery and utilization correlated well with the severity of mitochondrial myopathy as judged by the sum of the serum lactate and pyruvate content during exercise. Noninvasive tissue oximetry may be useful to measure the severity of myopathy and exercise intolerance in patients with mitochondrial myopathy.

Adult↗
PubMed2001

Cricopharyngeal achalasia is a common cause of dysphagia in patients with mtDNA deletions.

To assess dysphagia, the authors examined 12 patients with Kearns-Sayre syndrome (KSS) or chronic progressive external ophthalmoplegia (CPEO) due to mitochondrial DNA (mtDNA) deletion by videofluoroscopy and manometry. Cricopharyngeal achalasia was documented in nine of 12 patients (75%), whereas deglutitive coordination problems were found in one patient. Cricopharyngeal myotomy may be an effective treatment in selected cases with severe cricopharyngeal obstruction.

Adult↗
PubMed1993

Human aging is associated with various point mutations in tRNA genes of mitochondrial DNA.

In extraocular muscle tissue of elderly humans small amounts of point mutations in tRNA genes of mitochondrial DNA (mtDNA) were identified by point mutation-specific PCR. These mutations were not found in navel-string samples from newborns. While the mutations in tRNA(Leu(UUR)) (np 3243) and tRNA(Gly) (np 10006), previously identified in patients with MELAS and CIPO, respectively, were found in most elderly people, the mutations in tRNA(Ser(GCU)O (np 12246) and tRNA(Asn) (np 5692), identified in patients with CIPO and CPEO, respectively, were found only in two of 15 tissue samples from different individuals. The data suggest that some nucleotides of mtDNA represent "hot spots" for somatic mutations, which contribute to human aging.

Adolescent↗
PubMed2002

[A case of late onset mitochondrial neuromyopathy].

A 68-year-old woman was admitted with dysesthesia on both soles, hands and buttocks. She first noticed the dysesthesia in the left first toe two years before admission. One year before admission, serum creatine kinase and lactate dehydrogenase levels were elevated but she had no clinical symptoms suggesting myopathy. Nerve conduction study showed no apparent abnormalities, and an electromyogram showed mild myogenic change. Computed tomography of the muscle showed fatty degeneration of the trunk, major gluteus muscle, and biceps femoris muscle and atrophic change of the biceps femoris muscle. Muscle biopsy revealed a slight variation in fiber size, the presence of cytochrome c oxidase (CCO)-negative fibers by CCO staining, ragged-red fibers by Gomori trichrome staining, and mild denervation fiber by neuron specific enolase (NSE) staining. Analysis of her mitochondrial DNA (mtDNA) revealed a large deletion of mtDNA (approximately 8.5 Kb), and mitochondrial neuromyophy was diagnosed. The frequency of mtDNA deletion increases with aging. Although her mtDNA abnormality was compatible with chronic progressive external ophthalmoplegia (CPEO), we speculate that the aging process may be contributed to the mtDNA abnormality, which would be related to the late onset of her symptoms. As the phenotype of this mitochondrial disorder shows a wide variation and mtDNA abnormality is more frequent among elderly people, we should consider the possibility of mitochondrial disorders even in elderly people.

Age of Onset↗
PubMed2001

Oxidative stress in human aging and mitochondrial disease-consequences of defective mitochondrial respiration and impaired antioxidant enzyme system.

Respiratory function of mitochondria is compromised in aging human tissues and severely impaired in the patients with mitochondrial disease. A wide spectrum of mitochondrial DNA (mtDNA) mutations has been established to associate with mitochondrial diseases. Some of these mtDNA mutations also occur in various human tissues in an age-dependent manner. These mtDNA mutations cause defects in the respiratory chain due to impairment of the gene expression and structure of respiratory chain polypeptides that are encoded by the mitochondrial genome. Since defective mitochondria generate more reactive oxygen species (ROS) such as O2- and H2O2 via electron leak, we hypothesized that oxidative stress is a contributory factor for aging and mitochondrial disease. This hypothesis has been supported by the findings that oxidative stress and oxidative damage in tissues and culture cells are increased in elderly subjects and patients with mitochondrial diseases. Another line of supporting evidence is our recent finding that the enzyme activities of Cu,Zn-SOD, catalase and glutathione peroxidase (GPx) decrease with age in skin fibroblasts. By contrast, Mn-SOD activity increases up to 65 years of age and then slightly declines thereafter. On the other hand, we observed that the RNA, protein and activity levels of Mn-SOD are increased two- to three-fold in skin fibroblasts of the patients with CPEO syndrome but are dramatically decreased in patients with MELAS or MERRF syndrome. However, the other antioxidant enzymes did not change in the same manner. The imbalance in the expression of these antioxidant enzymes indicates that the production of ROS is in excess of their removal, which in turn may elicit an elevation of oxidative stress in the fibroblasts. Indeed, it was found that intracellular levels of H2O2 and oxidative damage to DNA and lipids in skin fibroblasts from elderly subjects or patients with mitochondrial diseases are significantly increased as compared to those of age-matched controls. Furthermore, Mn-SOD or GPx-1 gene knockout mice were found to display neurological disorders and enhanced oxidative damage similar to those observed in the patients with mitochondrial disease. These observations are reviewed in this article to support that oxidative stress elicited by defective respiratory function and impaired antioxidant enzyme system plays a key role in the pathophysiology of mitochondrial disease and human aging.

Aging↗
PubMed2002

A case of Kearns-Sayre syndrome with autoimmune thyroiditis and possible Hashimoto encephalopathy.

The Kearns-Sayre syndrome (characterized by onset before 20, chronic ophthalmoplegia, pigmentary retinal degeneration and at least 1 of the following symptoms: ataxia, heart block and high protein content in the cerebrospinal fluid) is a severe variant of chronic progressive external ophthalmoplegia (CPEO) with frequent re-arrangements of the mitochondrial DNA (mtDNA). The aim of this paper is to report a sporadic paediatric case of Kearns-Sayre syndrome with mtDNA heteroplasmic deletion, absence of cytochrome c oxidase in many muscle fibers, autoimmune thyroiditis followed by depressive phobic disturbances, slowing EEG, hyperreflexia, tremor and visual hallucinations, in which the diagnosis of possible encephalopathy associated with autoimmune thyroid disease (Hashimoto encephalopathy) was made. We speculated that in this patient, predisposed by mitochondrial deletion, anti-thyroid antibodies may have interfered with mitochondrial cerebral function, causing Hashimoto encephalopathy and facilitating ophthalmoplegia. It seems important to study anti-thyroid antibodies in every case of Kearns-Sayre syndrome, specially if ophthalmoplegia is recent, even in order to the therapy.

Brain Diseases↗
PubMed1992

The molecular genetics of mitochondrial cytopathies: the Melbourne experience.

Mitochondrial DNA is a unique, maternally inherited molecule encoding several subunits of the respiratory enzyme chain. In several mitochondrial cytopathies mutations have been described in this genome viz. large-scale heteroplasmic deletions in syndromes with progressive external ophthalmoplegia and point mutations in MELAS and MERRF encephalomyopathies. We here report Southern blot analyses in the cases of CPEO we have seen and describe the search for point mutations in MELAS and MERRF. Mitochondrial genetic sequencing in normal and disease controls as well as in patients has confirmed the pathogenic nature of a tRNA Lys point mutation in MERRF. We propose a novel mitochondrial structural gene mutation in a MELAS--like encephalomyopathy: an A-->G substitution at position 11084 leading to a Thr to Ala replacement in the ND4 subunit of complex I.

Base Sequence↗
PubMed1992

Mitochondrial diseases.

With the discovery of mitochondrial DNA (mtDNA) mutations in different neuromuscular disorders, investigations now seek to clarify how the mutant mtDNA induces biochemical and morphologic defects. In one of the most important approaches human mutant mtDNA is transferred into cells that lack mtDNA to examine the relationship between the amount of mutant mtDNA and defects in cell growth, respiration and enzyme activities. The resulting cells are 'cybrids'; these clonal cells contain the heteroplasmic mutant and normal mtDNA from patients with mitochondrial diseases. The mitochondria become functionally defective when the amount of mutant mtDNA exceeds a certain threshold, which differs from mutation to mutation: 60 to 70% in chronic progressive external ophthalmoplegia (CPEO) and probably 95% in the syndromes of mitochondrial encephalopathy, myopathy, lactic acidosis, and stroke-like episodes (MELAS), and myoclonic epilepsy with ragged red fibers (MERRF). This threshold effect may explain the tissue-specific patterns of clinical expression.

Chromosome Deletion↗
PubMed1992

[Strongly succinate dehydrogenase-reactive blood vessels (SSV) in various neuromuscular diseases].

The strongly succinate dehydrogenase-reactive blood vessels (SSV) are shown to have increased numbers of enlarged mitochondria in smooth muscle cells of the vessel wall on electron microscopy. They are seen in biopsied skeletal muscles from patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) at high frequency. The present study was done to examine the incidence of SSV in biopsied muscles from various neuromuscular diseases. Among 107 patients with mitochondrial encephalomyopathies (MEM) including 50 with chronic progressive external ophthalmoplegia (CPEO), 7 with myoclonus epilepsy with ragged-red fibers (MERRF), and 50 with MELAS, SSV were seen in nearly a half of the patients, and comprised approximately 24% of small arteries. On the other hand, SSV in 100 patients with various neuromuscular diseases other than MEM were exceptional, and only one of 8 patients with myotonic dystrophy had SSV. These findings suggest that the SSV are induced by functional abnormality of mitochondria in smooth muscle cells, and that an identification of the SSV is an additional crucial evidence to make a pathological diagnosis of MEM.

Blood Vessels↗
PubMed2003

Only transient increase of serum CoQ subset 10 during long-term CoQ10 therapy in mitochondrial ophthalmoplegia.

BACKGROUND: Coenzyme Q10 (CoQ10) is frequently administered in mitochondrial diseases. Mitochondrial dysfunction and CoQ10 treatment was also proposed in neurodegenerative disorders as amyotrophic lateral sclerosis and Parkinsons disease. PATIENTS AND METHODS: Seventeen patients with mitochondrial CPEO were treated with CoQ10 (dosage: 0.60 1.80 mg/kg body wt) in an open trial. Serum levels of CoQ10 were monitored before and after 6-9 and 12-15 months of CoQ10 therapy. CoQ10 concentration in muscle was measured in all patients before treatment. RESULTS: Prior to treatment CoQ10 concentration in muscle was normal in all patients. Eight patients completed the study after 12-15 months. Prior to treatment there was no correlation between CoQ10 in muscle and serum. There was no inverse correlation of serum lactate with CoQ10 in muscle before and in serum before and during therapy. CoQ10 serum level and body weight related CoQ10 dosage correlated significantly after 6-9 months but not after 12-15 months (p = 0.043 and n. s., respectively). During continued administration of CoQ10 the CoQ10 serum level was increased 2.76 +/- 1.00-fold after 6-9 months (range: 1.04-3.80). but returned to 1.70 +/- 0.98-fold after 12-15 months (range: 0.91-3.83). Serum lactate did not significantly change during treatment. There was no effect of CoQ10 treatment on signs and symptoms. CONCLUSION: The only transient increase of CoQ10 in serum has to be considered in any low dose long-term treatment with CoQ10.

Adolescent↗
PubMedDate not supplied

[A single deletion of mitochondrial DNA in a Brazilian patient with chronic progressive external ophthalmoplegia].

INTRODUCTION: The syndrome of chronic progressive external ophthalmoplegia (CPEO) has been associated to the presence of large deletion, single or multiple, in the mitochondrial DNA of skeletal muscle. CASE REPORT: We report a sporadic case of chronic progressive external ophthalmoplegia that began at age 19 years and was associated with ragged red fibers in skeletal muscle. Genetic analysis of mitochondrial DNA revealed the presence of a single deletion of 4237 bp that encompasses the nucleotide positions 9486 to 13722, a location that has not been described before, and flanked by a direct repeat sequence. The deletion is flanked by a direct repeat. CONCLUSIONS: The amount of deleted mitochondrial DNA (55%) in this patient's muscle suggests that this deletion is the molecular cause of the phenotypic presentation of this patient.

Adult↗
PubMed2006

Overview on visceral manifestations of mitochondrial disorders.

Mitochondriopathies (MCPs) that reach adult age not only manifest in the central and peripheral nervous systems, eyes, ears, and dermis, but also in visceral organs, such as endocrine organs, heart, liver, guts, kidneys and blood. Visceral manifestations occur as part of a multisystem involvement or rarely as single organ affection. Endocrinological abnormalities are found in the MELAS, MERRF , KSS , MID and DID MOAD syndromes. Cardiac involvement occurs in the MELAS, MERRF , KSS , CPEO, LHO N, NARP, and Leigh syndromes. Gastrointestinal manifestations are common in the MERRF , MNGI E, DID MOAD, and Leigh syndromes. Mitochondrial syndromes with renal manifestations are the KSS , Pearson, DID MOAD, and Leigh syndromes. The haematopoetic system is affected in the KSS , MERRF , and Leigh syndromes. In addition, visceral manifestations are found in many nonsyndromic MCPs. Although there is no causal therapy for MCPs, adequate symptomatic therapy, particularly of visceral manifestations, markedly improves quality of life and prognosis of these still often neglected or overlooked disorders.

Algorithms↗
PubMed1991

Oxidative energy failure in post-mitotic cells: a major factor in senescence.

A significant decline with age in state III respiration rates has been documented in man and experimental animals in several tissues. Focal areas of cytochrome oxidase negativity, resembling those in skeletal muscle fibres in patients with chronic progressive external ophthalmoplegia (CPEO) syndromes, appear in old age. The mitochondrial genome is susceptible to mutation because of a high turnover rate, ineffective DNA repair mechanisms and a hostile environment rich in free radicals. The available data supports the development of mitochondrial failure in old age in fixed post-mitotic tissues suggesting that mitochondrial failure may be central to the senescent process.

Aging↗
PubMed1989

Mitochondrial encephalomyopathies.

Increasingly numerous studies are being devoted to mitochondrial diseases, notably those which involve the neuromuscular system. Our knowledge and understanding of these diseases is progressing rapidly. We owe to Luft et al. (1962) the first description of this type of diseases. Their patient, a woman, presented with clinical symptoms suggestive of mitochondrial dysfunction, major histological abnormalities of skeletal muscle mitochondria and defective oxidative phosphorylation coupling clearly demonstrated in mitochondria isolated from muscle. This clinical, histological and biochemical triad led to the definition of mitochondrial myopathies. Subsequently, the triad was seldom encountered, and most mitochondrial myopathies were primarily defined by the presence of morphological abnormalities of muscle mitochondria. This review deals with the morphological, clinical, biochemical and genetic aspects of mitochondrial encephalomyopathies. The various morphological abnormalities of mitochondria are described. These are not specific of any particular disease. They may be present in some non-mitochondrial diseases and may be lacking in diseases due to specific defects of mitochondrial enzymes (e.g. carnitine palmityl-transferase or pyruvate dehydrogenase). The clinical classification of mitochondrial encephalomyopathies is discussed. There are two main schools of thought: the "lumpers" do not recognize specific syndromes within the spectrum of mitochondrial "cytopathies", the "splitters" try to identify specific syndromes while recognizing the existence of borderline cases. The following syndromes are described: chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayre syndrome (KSS), MERRF syndrome (myoclonic epilepsy with ragged-red fibers), MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes) and Leigh and Alpers syndromes. The biochemical classification comprises five types of abnormalities: defects of transport through the mitochondrial membrane, of substrate utilization, of Krebs' cycle, of oxidative phosphorylation and of various complexes of the respiratory chain. The clinical pictures corresponding to these defects are briefly described. The genetic aspects of these diseases are especially interesting because mitochondria have their own genome coding for thirteen proteins, all of them belonging to the respiratory chain. Genetic mitochondrial diseases may result from alterations of the nuclear genome, which are transmitted by mendelian inheritance, but they may also be due to alterations of the mitochondrial genome and transmitted by non-mandelian "maternal" heredity. A few examples are discussed, including Leber's optic atrophy and MERRF syndrome. (ABSTRACT TRUNCATED AT 400 WORDS)

Brain Diseases, Metabolic↗
PubMed1982

Chronic progressive external ophthalmoplegia. Clinical, electrophysiological, histochemical and ultrastructural studies of 14 cases.

Clinical, histochemical and ultrastructural findings concerning 14 cases with diagnosis of Chronic Progressive External Ophthalmoplegia are described. According to the clinical features the patients have been rated in two groups: the first including subjects with isolated ptosis or ptosis with external ophthalmoplegia and the second including subjects with a spreading of the muscular deficit and involvement of the neck and limbs. The most frequent histological and histochemical features are type I fibre atrophy, ragged-red fibres, DPNH-diaphorase reaction disorders and abnormal accumulation of lipids into the fibres. Electron microscopy reveal myofibrillar disorganization and clusters of polymorphous, abnormal mitochondria. In five cases mitochondria contain a variety of crystalline inclusions. Correlations between clinical data and histochemical and ultrastructural findings are discussed. Mitochondrial abnormalities are postulated to be a characteristic physiopathological pattern in CPEO.

Adult↗
PubMed1994

[Clinical characterization of diabetes mellitus in the families with mitochondrial encephalomyopathies].

We clinically characterized 18 diabetic patients in 7 families with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) and mitochondrial DNA mutations of tRNALEU(UUR) (3243), 5 diabetics in a family with myoclonic epilepsy and ragged red fiber (MERRF) and tRNALYS (8344) mutation and 11 diabetics in a family with chronic external ophthalmoplegia (CPEO) and multiple deletions. Insulin secretory capacities were significantly reduced in the mutant relatives, as compared with the non-mutant members. It is speculated that the mutation-induced OPHOS defects in the pancreatic beta- cells might result in insulin secretory defects.

DNA, Mitochondrial↗