[Show abstract][Hide abstract] ABSTRACT: Mitochondrial myopathy with episodic hyper-creatine kinase (CK)-emia (MIMECK) is a new disease entity characterized by episodic or persistent muscle weakness and elevated CK levels. We herein report two cases of MIMECK with the findings of histopathological studies. Histopathological examinations revealed strongly succinate dehydrogenase-reactive vessels. Electron microscopy showed abnormal mitochondria in the vessels and proliferating and vacuolated mitochondria under the sarcolemma. Both patients exhibited recurrent severe myalgia, weakness and increased CK levels. L-arginine treatment significantly ameliorated their muscle symptoms. These findings indicate that mitochondrial angiopathy plays an important role in the pathophysiology of MIMECK. L-arginine may be a potential therapeutic agent for this disorder.
Full-text · Article · Dec 2015 · Internal Medicine
[Show abstract][Hide abstract] ABSTRACT: The clinical features of myositis related with Human T-cell leukemia virus type 1 (HTLV-1) remains unclear despite epidemiological studies suggesting inflammatory myopathy associated with the virus.
Here, we described the clinical presentations, muscle biopsy studies and laboratory results of two siblings with HTLV-1-associated myelopathy / tropical spastic paraparesis (HAM/TSP) who were affected with lumbar lordosis. Computed tomography (CT) scans demonstrated marked paraspinal muscle atrophy in both patients. Immunohistochemical studies of biopsy tissue obtained from one of the patients revealed inflammatory change of the muscle. Upon oral prednisolone therapy, the patient showed improvement in muscle strength and serum creatine kinase (CK) level.
Myopathy or specifically axial myopathy should be considered as clinical symptom when treating the patients with HTLV-1 infection.
[Show abstract][Hide abstract] ABSTRACT: To determine the causative pathogen and investigate the effective treatment of a new type of encephalomyelitis with an unknown pathogen in Japan and report the preliminary ultrastructural and genomic characterization of the causative agent.
From 2005 to 2012, we treated 4 Japanese patients with geographic clustering and comparable clinical features, serum/CSF cytology, and radiologic findings. Brain biopsy was conducted in all patients to analyze neuropathologic changes by histology, and electron microscopy was applied to reveal the features of the putative pathogen. Genomic DNA was obtained from the affected brain tissues and CSF, and an unbiased high-throughput sequencing approach was used to screen for specific genomic sequences indicative of the pathogen origin.
All patients exhibited progressive dementia with involuntary tongue movements. Cytologic examination of CSF revealed elevated mononuclear cells. Abnormal MRI signals were observed in temporal lobes, subcortical white matter, and spinal cord. Biopsied brain tissue exhibited aggregated periodic acid-Schiff-positive macrophages and 2-7 μm diameter round/oval bodies without nuclei or cell walls scattered around the vessels. Unbiased high-throughput sequencing identified more than 100 archaea-specific DNA fragments. All patients were responsive to trimethoprim/sulfamethoxazole (TMP-SMX) plus corticosteroid therapy.
We report 4 cases of encephalomyelitis due to an unknown pathogen. On the basis of ultrastructural and genomic studies, we propose a new disease entity resulting from a causative pathogen having archaeal features. TMP-SMX therapy was effective against this new type of encephalomyelitis.
[Show abstract][Hide abstract] ABSTRACT: Mutation of the AMP deaminase 1 (AMPD1) gene, the predominate AMPD gene expressed in skeletal muscle, is one of the most common inherited defects in the Caucasian population; 2–3% of individuals in this ethnic group are homozygous for defects in the AMPD1 gene. Several studies of human subjects have reported variable results with some studies suggesting this gene defect may cause symptoms of a metabolic myopathy and/or easy fatigability while others indicate individuals with this inherited defect are completely asymptomatic. Because of confounding problems in assessing muscle symptoms and performance in human subjects with different genetic backgrounds and different environmental experiences such as prior exercise conditioning and diet, a strain of inbred mice with selective disruption of the AMPD1 was developed to study the consequences of muscle AMPD deficiency in isolation. Studies reported here demonstrate that these animals are a good metabolic phenocopy of human AMPD1 deficiency but they exhibit no abnormalities in muscle performance in three different exercise protocols.
Full-text · Article · Dec 2014 · Molecular Genetics and Metabolism Reports
[Show abstract][Hide abstract] ABSTRACT: Emery-Dreifuss muscular dystrophy (EDMD) is caused by mutations in the EMD gene on the X chromosome, which codes for emerin, an inner nuclear membrane protein. Monoclonal antibodies against the N-terminus of emerin protein are used to screen for emerin deficiency in clinical practice. However, these tests may not accurately reflect the disease in some cases. We herein describe the identification of a splice site mutation in the EMD gene in a Japanese patient who suffered from complete atrioventricular conduction block, mild muscle weakness and joint contracture, and a persistently elevated serum creatine kinase level. We used multiple antibodies to confirm the presence of a novel truncating mutation in emerin without the transmembrane region and C-terminus in the skeletal muscle.
No preview · Article · Jul 2014 · Internal Medicine
[Show abstract][Hide abstract] ABSTRACT: Nonsense-mediated mRNA decay (NMD) is an mRNA surveillance mechanism that eliminates aberrant mRNAs containing premature termination codons (PTCs). NMD inhibits the production of aberrant proteins that still retain, at least in part, wild-type function as well as dominant-negative peptides. Therefore, the selective inhibition of NMD has the potential to ameliorate NMD-exacerbated mutant phenotypes. However, we do not have sufficient knowledge of how to effectively suppress NMD with minimum cytotoxic effects. In this study, we aimed to identify NMD-related factors that can be targeted to efficiently inhibit NMD without causing significant cytotoxicity to restore the levels of truncated but partially functional proteins. We evaluated the knockdown of 15 NMD components in Ullrich congenital muscular dystrophy fibroblasts, which have a homozygous frameshift mutation causing a PTC in the collagen type VI α 2 gene. Of the 15 NMD factors tested, knockdown of SMG-8 produced the best effect for restoring defective mRNA and protein levels without affecting cell growth, cell-cycle progression, or endoplasmic reticulum stress. The efficacy of SMG-8 knockdown to improve the mutant phenotype was confirmed using another cell line, from a cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy patient who carries a PTC-containing mutation in HtrA serine peptidase 1. Our results suggest that SMG-8 is an appropriate target for inhibiting NMD to improve NMD-exacerbated mutant phenotypes. NMD inhibition by knockdown of SMG-8 may also be useful to induce synergy in combining the use of read-through drugs for patients with nonsense mutation-associated diseases.
No preview · Article · Aug 2013 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: Not only joint destruction but also muscle wasting due to rheumatoid cachexia has been problem in terms of quality of life of patients with rheumatoid arthritis (RA). In the present study, we performed histopathological examination and assessed relationships between characteristic parameters relating to muscle and joint swelling in a collagen-induced arthritis (CIA) model using cynomolgus monkeys (CMs).
Female CMs were used and CIA was induced by twice immunizations using bovine type II collagen with Freund's complete adjuvant. Arthritis level was evaluated from the degree of swelling at the peripheral joints of the fore and hind limbs. Food consumption, body weight, and serum biochemical parameters were measured sequentially. Five or 6 animals per time point were sacrificed at 2, 3, 5 and 9 weeks after the first immunization to obtain quadriceps femoris specimens for histopathology. Pimonidazole hydrochloride was intravenously administered to determine tissue hypoxia in skeletal muscle.
Gradual joint swelling was observed and the maximum arthritis score was noted at Week 5. In histopathology, necrosis of muscle fiber in the quadriceps femoris was observed only at Week 2 and the most significant findings such as degeneration, atrophy, and regeneration of muscle fiber were mainly observed at Week 5. Food consumption was decreased up to Week 4 but recovered thereafter. Body weight decreased up to Week 5 and did not completely recover thereafter. A biphasic increase in serum cortisol was also observed at Weeks 2 and 5. Histopathology showed that muscle lesions were mainly composed of degeneration and atrophy of the muscle fibers, and ATPase staining revealed that the changes were more pronounced in type II muscle fiber than type I muscle fiber. In the pimonidazole experiment, mosaic pattern in skeletal muscle was demonstrated in the intact animal, but not the CIA animal. Increased arthritis score was accompanied by a decrease in serum creatinine, a marker that reflects muscle mass.
Muscle wasting might exacerbate joint swelling in a collagen-induced arthritis model of cynomolgus monkeys.
[Show abstract][Hide abstract] ABSTRACT: AimUllrich congenital muscular dystrophy, caused by collagen VI deficiency, is heterogeneous in both clinical and pathological phenotype. The aim of the present study was to identify the molecular mechanisms in two sporadic Japanese patients with congenital multiple joint contractures, hyperextension of joints and muscle weakness, but without severe respiratory failure in their 20s. Methods
Collagen VI and several other congenital muscular dystrophy-related proteins were examined with immunohistochemical staining on biopsies of skeletal muscle. Using a high-throughput next-generation sequencing system, we screened the COL6A1, COL6A2 and COL6A3 genes. A confocal microscopy study was then applied to detect the potential partial deficiency of collagen VI, and to confirm the pathogenicity of the suspected mutations. ResultsNo diagnostic abnormality was observed by conventional immunohistochemical staining. The mutation screening discovered two novel heterozygous mutations, c.1499G>A (p.G500E) in COL6A1 and c.801G>T (p.K267N) in COL6A2, in patient 1 and 2, respectively. Subsequently, we identified discontinuous expression of collagen VI in the basal lamina and blood vessels by confocal microscopy study. Conclusion
We established a diagnostic procedure for suspected collagen VI-related disorders, specifically for the patients with a mild phenotype and without diagnostic information in the routine pathological studies. The partially preserved collagen VI in the two patients could be involved in the relatively benign clinical phenotype.
[Show abstract][Hide abstract] ABSTRACT: Background and aims:
In mitochondrial myopathy, autophagy is presumed to play an important role in mitochondrial dysfunction. Rimmed vacuoles (RVs), a sign of autophagy, can be seen as a secondary phenomenon in muscle ragged-red fibres (RRFs), whereas the uncommon presentation is that some fibres contain RVs, but without any mitochondrial abnormalities. To investigate the pathogenesis beneath this pathological phenomenon.
We reviewed 783 skeletal muscle specimens and selected five obtained from patients with suspected mitochondrial myopathy, characterised by clearly visible autophagic vacuoles in non-RRFs, besides the coexistence of RRFs and cytochrome oxidase-negative fibres. Immunohistochemical staining with LC-3, and electron microscopy studies were performed. Using resequencing microarray and a next-generation sequencing system, the mitochondrial DNA was screened for mutations and the heteroplasmic level was measured in skeletal muscle and blood.
Muscle fibres with RVs and RRFs, as well as some morphologically normal fibres, stained strongly for LC-3. Electron microscopy disclosed significant abnormal mitochondrial proliferation and existence of autophagic vacuoles. After mutation screening, m.8344A>G in the tRNA(Lys) gene was detected in two patients. The heteroplasmy of mutated G was 45.1% in skeletal muscle and 17.8% in blood in patient 1; patient 2 exhibited 80.3% mutated G in skeletal muscle and 25.2% in blood.
These findings demonstrate a new pathological phenotype for the m.8344A>G mutation- related disease and also provide pathological evidence of a correlation between mitochondrial abnormalities and autophagy.
No preview · Article · Apr 2013 · Journal of clinical pathology
[Show abstract][Hide abstract] ABSTRACT: Objective:
Dysferlinopathies belong to heterogeneous group of autosomal recessive muscular disorders caused by mutations in the gene encoding dysferlin. The classifications of the dysferlinopathies mainly include limb-girdle muscular dystrophy 2B (LGMD2B) with predominantly proximal weakness, Miyoshi myopathy (MM) with calf muscle weakness and atrophy, and distal myopathy with anterior tibial onset (DMAT) with tibialis muscle atrophy. We describe the genetic character of dysferlinopathies in a group of Chinese patients.
DYSF mutations screening were done after muscle biopsy and immunohistochemical staining.
Eight patients showed an absence or drastic decrease of dysferlin expression in biopsied muscle. We identified 6 different mutations, including one nonsense mutation, two insertion mutation, two deletion mutations and one splice site mutation. Five of them were novel mutations.
We described 8 Chinese patients with dysferlinopathy (four had a distal phenotype of MM; one had a phenotype of DMAT and three presented with LGMD2B). It is the first report of genetic confirmed DMAT in China. Mutations c.3112C>T and c.1045dup, may be recurrent mutations in China.
No preview · Article · Dec 2012 · Clinical neurology and neurosurgery
[Show abstract][Hide abstract] ABSTRACT: We report two patients with myotonic dystrophy type 1 (DM1) showing winged scapula in a single family. Genomic analysis revealed a marked expansion of CTG repeats in the 3' untranslated region; 1100 in patient 1 and 667 in patient 2. Muscle MRI revealed marked atrophy in the serratus anterior muscle in both patients. Muscle biopsy findings showed central nuclei and variations in fiber size. One of the patients showed ragged red fibers in muscles of the biceps brachii. To our knowledge, this is the first report of typical winged scapula in DM1.
No preview · Article · Jun 2012 · Neuromuscular Disorders
[Show abstract][Hide abstract] ABSTRACT: Inclusion body myositis is an inflammatory myopathy characterized pathologically by rimmed vacuoles and the accumulation of amyloid-related proteins. Autopsy studies in these patients, including histochemical examinations of multiple skeletal muscles, have not yet been published. In this paper, we describe the autopsy findings of a patient with inclusion body myositis and hypertrophic cardiomyopathy. A 69-year-old man, who was a human T lymphotropic virus type 1 carrier, exhibited slowly progressive muscle weakness and atrophy, predominantly affecting the scapular, quadriceps femoris, and forearm flexor muscles. His disease course was more rapidly progressive than that typically observed; the patient died suddenly of arrhythmia 5 years after diagnosis. Autopsy findings revealed that multiple muscles, including the respiratory muscles, were involved. Longitudinal studies revealed an increased frequency of rimmed vacuoles and p62/sequestosome 1- and/or TAR DNA-binding protein 43-positive deposits in autopsied muscles, although the amount of inflammatory infiltrate appeared to be decreased. We speculated that muscle degeneration may be more closely involved in disease progression compared with autoimmunity. Genetic analysis revealed a myosin binding protein C3 mutation, which is reportedly responsible for familial hypertrophic cardiomyopathy. This mutation and human T lymphotropic virus type 1 infection may have affected the skeletal muscles of this patient.
No preview · Article · May 2012 · Neuromuscular Disorders
[Show abstract][Hide abstract] ABSTRACT: Objective: Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme, acid alpha-glucosidase (GAA). To the best of our knowledge, no studies have reported the results of systematic and sequential CT analyses before and during ERT. In this study we have treated three patients with late onset Pompe disease by ERT, and investigated the efficacy of treatment by computed tomography number. Methods: We measured the serial changes in the computed tomography (CT) number of multiple organs in three patients with late onset of Pompe disease during 24months of enzyme replacement therapy (ERT). Results: Before treatment, the liver and muscle CT numbers were higher in these patients than in the controls. The liver CT number decreased after performing ERT. Furthermore, the urinary glucose tetrasaccharide levels, a biomarker of glycogen accumulation, were elevated before ERT and reduced thereafter. Conclusions: The findings in these cases suggest that the elevation of the liver CT number represents glycogen accumulation in the liver and that the analysis of the liver CT number is therefore a useful tool for assessing the efficacy of ERT.
No preview · Article · Apr 2012 · Brain & development
[Show abstract][Hide abstract] ABSTRACT: To elucidate the relationship between mitochondrial DNA (mtDNA) alterations and a mitochondrial disease with a distinct combination of characteristic symptoms, namely episodic hyper-creatine kinase (CK)-emia and mild myopathy.
We selected 9 patients with mtDNA np8291 alteration from 586 patients suspected to have a mitochondrial disease, and assessed them clinically, pathologically, and genetically. These 9 patients had undiagnosed mitochondrial myopathy with episodic hyper-CK-emia, all showing similar symptoms and progression.
Patients had mild muscle weakness and episodic hyper-CK-emia triggered by infections or drugs. Five of 9 patients were initially diagnosed with other conditions, such as myasthenia gravis, polymyositis, viral myositis, and drug-induced myopathy, because these conditions were acute or subacute, and 9 patients showed the same 16 mtDNA alterations, which have been reported to be nonpathological polymorphisms. Muscle biopsy revealed ragged-red fibers, highly expressed succinate dehydrogenase staining fibers, and cytochrome c oxidase-deficient fibers. Because their mitochondrial sequence data was almost the same, and 9 patients live in widely separated cities in Japan, the alterations may have arisen from a single source.
These findings suggest that mild myopathy with episodic hyper-CK-emia associated with some of the 16 mtDNA alterations or at least with their mitochondria, could be a novel mitochondrial disease. Therefore, we propose that this disease be named as "mitochondrial myopathy with episodic hyper-CK-emia (MIMECK)." These alterations could work concomitantly and probably modify the impact of medications or other environmental factors. We believe these findings provide an insight into a novel aspect of mitochondrial disease pathogenesis.
No preview · Article · Sep 2011 · Annals of Neurology
[Show abstract][Hide abstract] ABSTRACT: Objectives: Epidemiological studies show that human T-lymphotropic virus type 1 (HTLV-1) is closely associated with polymyositis (PM). However, the pathogenic roles of HTLV-1 in PM remain unknown. The present study aims to assess skeletal muscle morphology in the presence of HTLV-1 infection to compare the histopathological findings of HTLV-1-positive and HTLV-1-negative PM.
Methods: Among the 68 patients with inflammatory myopathy diagnosed through muscle biopsy over the previous 10 years at Kagoshima University Hospital, we retrospectively selected 21 patients with PM not associated with any other disease; we evaluated HTLV-1 positivity through serology, confirmed it by nested polymerase chain reaction using DNA extracted from muscles, and then assessed the tissue viral load. Meticulous histopathological examination was carried out using routine histochemical and immunohistochemical staining, and specimens from selected cases were examined by electron microscopy.
Results: The clinical and histopathological findings of muscle biopsy specimens of HTLV-1-positive (n = 11) and HTLV-1-negative PM cases (n = 10) were compared. Compared with HTLV-1-negative patients, HTLV-1-positive patients showed protracted clinical courses, prominent endomysial infiltrates, infrequent necrotic fibers and prominent regenerative activities. Furthermore, they showed frequent cytochrome c oxidase deficiency and ultrastructural abnormalities in mitochondria.
Conclusions: These differences are significant, but not specific to HTLV-1-positive PM. Therefore, HTLV-1 might induce the clinical and histopathological modifications of PM observed in the present study. (Clin. Exp. Neuroimmunol. doi: 10.1111/j.1759-1961.2011.00017.x, January 2011)
[Show abstract][Hide abstract] ABSTRACT: Axial myopathy is a rare neuromuscular disease that is characterized by paraspinal muscle atrophy and abnormal posture, most notably camptocormia (also known as bent spine). The genetic cause of familial axial myopathy is unknown. Described here are the clinical features and cause of late-onset predominant axial myopathy and encephalopathy. A 73-year-old woman presented with a 10-year history of severe paraspinal muscle atrophy and cerebellar ataxia. Her 84-year-old sister also developed late-onset paraspinal muscle atrophy and generalized seizures with encephalopathy. Computed tomography showed severe atrophy and fatty degeneration of their paraspinal muscles. Their mother and maternal aunt also developed bent spines. The existence of many ragged-red fibers and cytochrome c oxidase-negative fibers in the biceps brachii muscle of the proband indicated a mitochondrial abnormality. No significant abnormalities were observed in the respiratory chain enzyme activities; however, the activities of complexes I and IV were relatively low compared with the activities of other complexes. Sequence analysis of the mitochondrial DNA from the muscle revealed a novel heteroplasmic mutation (m.602C>T) in the mitochondrial tRNA(Phe) gene. This familial case of late-onset predominant axial myopathy and encephalopathy may represent a new clinical phenotype of a mitochondrial disease.
Full-text · Article · Mar 2011 · Acta Neuropathologica
[Show abstract][Hide abstract] ABSTRACT: It has been suggested that mitochondrial dysfunction is important in the pathogenesis of psychiatric disorders such as depression, schizophrenia and dementia. We report herein three adult patients exhibiting such psychiatric symptoms as the core manifestation, accompanied by various degrees of myopathic symptoms. Pathological findings in biopsied skeletal muscle were compatible with mitochondrial myopathy in all cases. Maternal inheritance was not apparent in all three cases; however, two patients were born to consanguineous parents. Mutation analysis on the mitochondrial DNA (mtDNA) and seven nuclear genes, in which pathogenic mutations are known to cause mtDNA deletions, was performed. MtDNA deletion mutations were identified in skeletal muscles of all patients. Neither pathogenic mutations nor copy number variation was identified among the nuclear genes. Although further studies are needed, the molecular pathways inducing mitochondrial abnormalities may be implicated in a variety of psychiatric conditions.
No preview · Article · Dec 2010 · Neuroscience Research