Apoptotic muscle fiber degeneration in distal myopathy with rimmed vacuoles

Rimmed vacuole formation, tubulofilamentous nuclear inclusions and muscle fiber atrophy are the characteristic pathological findings in distal myopathy with rimmed vacuoles (DMRV). Necrotic muscle fibers were few in number and did not appear to account for the muscle weakness, but the nuclear changes with myofibrillar degeneration followed by rimmed vacuole formation appeared to be the major reason for the muscle fiber atrophy in DMRV. To determine whether the nuclear change in DMRV was related to apoptosis, we examined 15 muscle biopsy specimens immunohistochemically, and 7 of them ultrastructurally. The characteristic tubulofilamentous nuclear inclusions were found in 4 and the typical fragmented apoptotic nuclei in 3 of the 7 muscle biopsy samples examined by electron microscopy. TUNEL-positive nuclei reflecting apoptotic DNA fragmentation were found in 13 of 15 biopsies ranging from a few to approximately 1.5% of myonuclei. Apoptosis-specific protein was expressed in the sarcoplasm of atrophic fibers in 13 biopsies both with or without rimmed vacuoles. These findings suggest that the apoptotic process plays a crucial role in myofibrillar degeneration followed by autophagocytosis, i.e., rimmed vacuole formation, in DMRV.

Caveolin-3 deficiency causes muscle degeneration in mice

Caveolin-3 is a muscle-specific protein integrated in the caveolae, which are small invaginations of the plasma membrane. Mutations of the caveolin-3 gene, localized at 3p25, have been reported to be involved in the pathogenesis of limb-girdle muscular dystrophy (LGMD1C or caveolinopathy) with mild clinical symptoms, inherited through an autosomal dominant form of genetic transmission. To elucidate the pathogenetic mechanism, we developed caveolin-3-deficient mice for use as animal models of caveolinopathy. Caveolin-3 mRNA and its protein were absent in homozygous mutant mice. In heterozygous mutant mice, both the mRNA and its protein were normal in size, but their amounts were reduced by about half. The density of caveolae in skeletal muscle plasma membrane was roughly proportional to the amount of caveolin-3. In homozygous mutant mice, muscle degeneration was recognized in soleus muscle at 8 weeks of age and in the diaphragm from 8 to 30 weeks, although there was no difference in growth and movement between wild-type and mutant mice. No apparent muscle degeneration was observed in heterozygous mutant mice, indicating that pathological changes caused by caveolin-3 gene disruption were inherited through the recessive form of genetic transmission.

Siblings of Schwartz-Jampel syndrome with abnormal muscle computed tomographic findings

Schwartz-Jampel syndrome (SJS) is a disorder characterized by myotonia, joint contractures, skeletal abnormalities, facial dysmorphism and growth retardation. We present two boys of ages 4 and 8 years with SJS. Their clinical, electromyographic and histopathological findings were similar to those described, except for computed tomography (CT) images that revealed diffuse high attenuation in sternocleidomastoid muscles and low attenuation in the paraspinal, quadriceps, sartorius, soleus and gastrocnemius muscles. This is the first report describing abnormal muscle CT findings associated with SJS. Additional studies of muscle CT might help to improve understanding of the pathogenesis of SJS.

Frequent mutations in Japanese patients with acid maltase deficiency

We screened 22 Japanese patients with acid maltase deficiency (seven with the infantile type, eight with the juvenile type and seven with the adult type) for three previously described mutations, D645E, S529V and R672Q, and a novel mutation, R600C. Although D645E has been reported to be common in Chinese patients with the infantile type, only three of 44 alleles (two of 14 infantile type alleles) from Japanese patients harbored the D645E mutation. The S529V mutation was identified in six of 14 alleles from adult-onset patients. None of the infantile or juvenile patients harbored the S529V mutation. Therefore, S529V apparently results in the adult type disease and is common in Japanese adult-onset patients. R672Q was identified in two pairs of siblings with the juvenile type. A novel mutation, R600C, was identified in eight of 22 patients (nine of 44 alleles). Therefore, R600C is another common Japanese mutation occurring at a CpG dinucleotide "hot spot". Homozygosity for this mutation apparently results in the infantile phenotype. Genetic diagnosis by detecting these four mutations might be feasible for most Japanese patients with acid maltase deficiency.

[Myositis and rhabdomyolysis with influenza infection]

Myositis and rhabdomyolysis with influenza are rare, but sometimes serious complications. Patients with myositis more commonly have influenza B infection than influenza A. On the other hand, rhabdomyolysis are more frequently recognized in patients with influenza A infection than those with influenza B. Upper respiratory symptoms usually precede myositis, while rhabdomyolysis occurs simultaneously or shortly after the respiratory symptoms. Creatine kinase levels are elevated in myositis mildly and in rhabdomyolysis markedly. Influenza myositis improve spontaneously within 6 weeks, but influenza rhabdomyolysis sometimes induce renal failure with fatal outcome. Although the true incidence of myositis and rhabdomyolysis in the influenza infection remains unknown, careful medical care is necessary when patients have muscle pain and weakness.

[A patient of infantile polymyositis triggered by respiratory syncytium virus infection]

An 11-month-old boy developed acute polymyositis about 1 week after respiratory syncytium virus (RSV) pneumonia. He was admitted to our hospital because of interstitial pneumonia. RSV infection was confirmed by the presence of its antigen in his nasal discharge. Two weeks later, his chest X-ray findings improved and RSV antigen became negative, but severe generalized muscle weakness developed, causing respiratory failure. Muscle biopsy demonstrated inflammatory cellular infiltration with occasional fiber necrosis. Intravenous steroid pulse therapy was remarkably effective resulting in complete recovery of his muscle power. In this patient polymyositis was preceded with RSV infection, suggesting a close relationship between polymyositis and RSV infection. Although many patients of viral myositis have been reported to be associated with coxsackie B, HCV and HTLV-1 viruses, our patient is the first infantile polymyositis secondary to RSV infection.

Generation of mice with mitochondrial dysfunction by introducing mouse mtDNA carrying a deletion into zygotes

Mice carrying mitochondrial DNA (mtDNA) with pathogenic mutations would provide a system in which to study how mutant mtDNAs are transmitted and distributed in tissues, resulting in expression of mitochondrial diseases. However, no effective procedures are available for the generation of these mice. Isolation of mouse cells without mtDNA (rho0) enabled us to trap mutant mtDNA that had accumulated in somatic tissues into rho0 cells repopulated with mtDNA (cybrids). We isolated respiration-deficient cybrids with mtDNA carrying a deletion and introduced this mtDNA into fertilized eggs. The mutant mtDNA was transmitted maternally, and its accumulation induced mitochondrial dysfunction in various tissues. Moreover, most of these mice died because of renal failure, suggesting the involvement of mtDNA mutations in the pathogeneses of new diseases.

A case of Walker-Warburg syndrome

Walker-Warburg syndrome (WWS) is an autosomal recessive disorder characterized by type II lissencephaly, cerebellar and retinal anomalies, and congenital muscular dystrophy. We report a female diagnosed with WWS based on clinical criteria. This patient was found to have fetal hydrocephalus on ultrasonography at 29 weeks of gestation, and exhibited severe hypotonia, ocular malformations, and hydrocephalus at birth. MRI revealed type II lissencephaly, hydrocephalus, and other severe brain malformations. Genetic analysis was performed to distinguish WWS from severe Fukuyama-type congenital muscular dystrophy (FCMD), which has numerous findings in common. This revealed no expression of the founder haplotype or single-stranded conformation polymorphism (SSCP) abnormalities. Since the life expectancy of patients with FCMD is longer, differential diagnosis should be performed precisely.

[Overloading to neck extensor muscles is an aggravating factor to induce further neck drop in isolated neck extensor myopathy (Katz). A case report]

A 78-year-old woman was hospitalized because of progressive anterior neck drop over 4 months prior to admission. She was normal except for mild weakness of her neck, trapezius and biceps brachii muscles. EMG revealed mild myopathic changes in the neck extensors, trapezius, deltoid and sternocleidomastoid muscles. Bilateral splenius capitis muscles had high intensities on T2-weighted and STIR pulse-sequenced MRI. However, there were no inflammatory changes in the right splenius muscle biopsy. Accordingly, the abnormal MRI finding seems not to result from an inflammatory process but from an physiological increase of intracellular water content due to sustained muscle contraction. Because apparent neuromuscular diseases responsible for neck drop were excluded, her clinical features met the criteria of isolated neck extensor myopathy (INEM, Katz). After strict bed-rest for one month, her neck drop improved dramatically. When she returned to the previous life style after discharge, her symptoms of the neck drop reappeared. Although the cause of INEM remains unclear, the present case indicates that the condition is reversible at least in the early stage of the disease, and the overloading to the neck extensor muscles is an aggravating factor of the neck drop in INEM.

[Muscle involvement of Stormorken's syndrome]

We described two patients, a mother and daughter, of Stormorken's syndrome. The syndrome is characterized clinically by autosomal dominant inheritance, congenital miosis, thrombocytopenia, asplenia and muscle weakness. Both patients had bleeding tendency, ichthyosis of arms, and muscle weakness. The daughter additionally had short stature (146 cm), low body weight (32 kg) and muscle cramp. Neurological findings of the patients included migraine-like headache, cognitive dysfunction, limitation of upward and lateral gaze, and amydriasis. Femoral muscle MRI of the daughter demonstrated decreased volume with patchy high intensity areas in the hamstrings. A muscle biopsy from the daughter showed myogenic changes with muscle fiber necrosis and regeneration, variation in fiber size, tubular aggregates in approximately 5% of fibers, and fibrous tissue proliferation. Dystrophin, dystrophin-associated proteins and dysferlin were normally expressed. Although both patients had elevated creatine kinase levels and generalized muscle wasting, muscle weakness was mild with slow progression. A certain membrane defect in the platelet and muscle fiber might be responsible for the pathogenesis of this syndrome.

Primary LAMP-2 deficiency causes X-linked vacuolar cardiomyopathy and myopathy (Danon disease)

"Lysosomal glycogen storage disease with normal acid maltase" which was originally described by Danon et al., is characterized clinically by cardiomyopathy, myopathy and variable mental retardation. The pathological hallmark of the disease is intracytoplasmic vacuoles containing autophagic material and glycogen in skeletal and cardiac muscle cells. Sarcolemmal proteins and basal lamina are associated with the vacuolar membranes. Here we report ten unrelated patients, including one of the patients from the original case report, who have primary deficiencies of LAMP-2, a principal lysosomal membrane protein. From these results and the finding that LAMP-2-deficient mice manifest a similar vacuolar cardioskeletal myopathy, we conclude that primary LAMP-2 deficiency is the cause of Danon disease. To our knowledge this is the first example of human cardiopathy-myopathy that is caused by mutations in a lysosomal structural protein rather than an enzymatic protein.

Walker-Warburg syndrome is genetically distinct from Fukuyama type congenital muscular dystrophy

A female patient who fulfilled the diagnostic criteria of Walker-Warburg syndrome had muscle biopsy finding of muscular dystrophy. There was normal expression of merosin (laminin alpha2 chain) and dystrophin and only slightly reduced dystrophin-associated glycoprotein expression. On genetic analysis, she had no specific haplotype, the common mutation of 3kb insertion, or point mutations in the Fukuyama-type congenital muscular dystrophy gene, suggesting that the two diseases are not genetically identical.

Muscle mitochondrial changes by experimental immobility and hindlimb suspension

It is one of the key themata to investigate the circulatory, muscular, nervous and nutritional systems when humans stay for long time in the space environment in order to improve the safety and efficiency in manned space flight. It is well known that immobility and microgravity [correction of microgravidity] induce selective skeletal muscle atrophy. Previous experiments indicated red soleus muscle was selectively involved and the most striking finding was myofibrillar degeneration without necrosis or phagocytosis. This study is focused on the mitochondrial function in this degenerative process because red soleus muscle contains much mitochondria than white muscles, and mitochondrial changes may be closely associated with the core structure observed as the myofibrillar disorganization.

Dependence of normal development of skeletal muscle in neonatal rats on load bearing

Antigravity function plays an important role in determining the morphological and physiological properties of the neuromuscular system. Inhibition of the normal development of the neuromuscular system is induced by hindlimb unloading during the neonatal period in rats. However, the role of gravitational loading on the development of skeletal muscle in rats is not well understood. It could be hypothesized that during the early postnatal period, i.e. when minimal weight-supporting activity occurs, the activity imposed by gravity would be of little consequence in directing the normal development of the skeletal musculature. We have addressed this issue by limiting the amount of postnatal weight-support activity of the hindlimbs of rats during the lactation period. We have focused on the development of three characteristics of the muscle fibers, i.e. size, myonuclear number and myosin heavy chain expression.

[Two sibling patients with non-Fukuyama type congenital muscular dystrophy with low serum selenium levels--therapeutic effects of oral selenium administration]

We report a pair of siblings with non-Fukuyama type, merosin-positive congenital muscular dystrophy, born to unrelated parents. Patient 1 was a 16-year-old girl with myopathy, cardiomyopathy, severe mental retardation and epilepsy. Patient 2 was a younger brother of patient 1, a 10-year-old boy with myopathy, severe mental retardation and epilepsy. Their serum selenium levels were decreased to 25 micrograms/l and 55 micrograms/l, respectively (normal 97-147 micrograms/l). Their muscle biopsy findings were similar to those seen in selenium deficient myopathy, showing abnormal mitochondrial distribution and giant mitochondria. After oral administration of selenium for 3 months, their gait disturbance apparently improved, which was confirmed by a gait analysis system. Why their gait improved remain unclear, but a defect in selenium metabolism may play a role in the development of congenital muscular dystrophy and mental retardation.

Haemopoietic biglycan produced by brain cells stimulates growth of microglial cells

We have recently found that soluble biglycan purified from rat thymic myoid cells had haemopoietic activity capable of inducing preferential growth and differentiation of monocytic lineage cells from various haemopoietic sources, including brain microglial cells. In the present study, to understand developmental mechanisms of microglial/monocytic cells in the brain, we have attempted to identify haemopoietic activity of the brain biglycan. The mRNA and the immunological epitope of biglycan were detected in the rat brain homogenates and several rat glial cell lines. Immunohistochemical study showed that several different types of brain cells produced biglycan. During development biglycan synthesis in the brain appeared to be increased. The brain haemopoietic biglycan was easily separated by DEAE-Sepharose chromatography from the macrophage colony stimulating factor (M-CSF) which was concomitantly produced from the brain cells. The brain haemopoietic biglycan, purified through immunoaffinity column, indeed stimulated growth of primarily cultured microglial cells. Taken together, these results suggest that the haemopoietic biglycan plays an important role in generating brain-specific circumstances for development of microglial/monocytic cells.

Expression of MyoD and myogenin in dystrophic mice, mdx and dy, during regeneration

Expression of two myogenic regulatory factors, MyoD and myogenin, was studied in regenerating muscles of dystrophic mice and compared to a chemically induced regeneration process. First, the distribution of the two proteins was determined immunohistochemically at various time points after single administrations of a local anaesthetic, bupivacaine hydrochloride, which causes myonecrosis followed by regeneration. Detectable levels of MyoD appeared at 18 h and the expression reached their maximum levels at 48 h after the injection, which coincide with the stage when satellite cells are activated and start to proliferate. Myogenin became detectable in 24 h and its expression reached its highest level at 72 h after injection when newly formed myotubes appeared. The two genes were also expressed in the dystrophic muscles from dy and mdx mice which exhibit dystrophic pathological features but are associated with different phenotypes. In mdx mice the two genes were expressed at reasonably high levels in parallel with the active regenerating process, whereas in dy mice MyoD and myogenin expressions decreased as fibrosis progressed. However, MyoD was relatively more strongly expressed in the larger mature myotubes of dy mice than in those of mdx mice, suggesting prolonged regenerative activity. In dy and mdx mice, MyoD and myogenin were expressed in different quantities, indicating that these animals have distinct regenerating activities. Our findings confirm that expression of both MyoD and myogenin genes is necessary in the regenerative process for the proliferation of satellite cells (myoblasts) and for the development of early regenerating fibers (myotubes) even in dystrophic muscles.

Central core disease and congenital neuromuscular disease with uniform type 1 fibers in one family

We report a family in which the father had central core disease and his son had congenital neuromuscular disease with uniform type 1 fibers. This is the first report of such a combination. Although they had no recognized mutation in the ryanodine receptor gene, it is highly likely that the son also had central core disease but without core structures. The absence of cores may be due to the muscle sample or the young age of the patient since core structures have been reported to increase with age. Although the prevalence of core structures in individual muscles is unknown, there is a possibility of sampling error. In some patients, congenital neuromuscular disease with uniform type 1 fibers is closely related to or identical with central core disease.

Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder defined clinically by severe gastrointestinal dysmotility; cachexia; ptosis, ophthalmoparesis, or both; peripheral neuropathy; leukoencephalopathy; and mitochondrial abnormalities. The disease is caused by mutations in the thymidine phosphorylase (TP) gene. TP protein catalyzes phosphorolysis of thymidine to thymine and deoxyribose 1-phosphate. We identified 21 probands (35 patients) who fulfilled our clinical criteria for MNGIE. MNGIE has clinically homogeneous features but varies in age at onset and rate of progression. Gastrointestinal dysmotility is the most prominent manifestation, with recurrent diarrhea, borborygmi, and intestinal pseudo-obstruction. Patients usually die in early adulthood (mean, 37.6 years; range, 26-58 years). Cerebral leukodystrophy is characteristic. Mitochondrial DNA (mtDNA) has depletion, multiple deletions, or both. We have identified 16 TP mutations. Homozygous or compound heterozygous mutations were present in all patients tested. Leukocyte TP activity was reduced drastically in all patients tested, 0.009 +/- 0.021 micromol/hr/mg (mean +/- SD; n = 16), compared with controls, 0.67 +/- 0.21 micromol/hr/mg (n = 19). MNGIE is a recognizable clinical syndrome caused by mutations in thymidine phosphorylase. Severe reduction of TP activity in leukocytes is diagnostic. Altered mitochondrial nucleoside and nucleotide pools may impair mtDNA replication, repair, or both.

Myopathy phenotype of transgenic mice expressing active site-mutated inactive p94 skeletal muscle-specific calpain, the gene product responsible for limb girdle muscular dystrophy type 2A

A defect of the gene for p94 (calpain 3), a skeletal muscle-specific calpain, is responsible for limb girdle muscular dystrophy type 2A (LGMD2A), or 'calpainopathy', which is an autosomal recessive and progressive neuromuscular disorder. To study the relationships between the physiological functions of p94 and the etiology of LGMD2A, we created transgenic mice that express an inactive mutant of p94, in which the active site Cys129 is replaced by Ser (p94:C129S). Three lines of transgenic mice expressing p94:C129S mRNA at various levels showed significantly decreased grip strength. Sections of soleus and extensor digitorum longus (EDL) muscles of the aged transgenic mice showed increased numbers of lobulated and split fibers, respectively, which are often observed in limb girdle muscular dystrophy muscles. Centrally placed nuclei were also frequently found in the EDL muscle of the transgenic mice, whereas wild-type mice of the same age had almost none. There was more p94 protein produced in aged transgenic mice muscles and it showed significantly less autolytic degradation activity than that of wild-type mice. Although no necrotic-regenerative fibers were observed, the age and p94:C129S expression dependence of the phenotypes strongly suggest that accumulation of p94:C129S protein causes these myopathy phenotypes. The p94:C129S transgenic mice could provide us with crucial information on the molecular mech-anism of LGMD2A.

[Congenital nemaline myopathy with mitochondrial abnormalities. An adult case report]

We report a 42-year-old male suffering from congenital nemaline myopathy accompanied with mitochondrial abnormalities in his muscle biopsy. He had a dysmorphic face with a high-arched and narrow palate and slowly progressive generalized muscle weakness. He was still able to walk with a cane. CT showed symmetrical muscle atrophy and low densities in the thigh muscles, especially in the posterior compartment, and in the soleus muscles. Preferential posterior thigh involvement was unusual in congenital nemaline myopathy. The lumbar quadrate and paravertebral muscles were relatively well preserved; these muscles were reported to be severely involved in adult-onset nemaline myopathy patients. Muscle biopsy findings were consistent with nemaline myopathy; nemaline rods in approximately 10% of fibers, type 1 fiber atrophy, and type 2B fiber deficiency. In addition, ragged-red fibers were scattered and focal cytochrome c oxidase (CCO) deficiency was present. Formazan granules were large on succinate dehydrogenase stain. Many fibers with nemaline rods showed focal CCO deficiency. On electron microscopy, large (megaconial) mitochondria were lined regularly between Z lines. PCR and Southern blot analysis of muscle mitochondrial DNA revealed multiple deletions. It remains to be clarified whether mitochondrial abnormalities are primarily related to nemaline myopathy or secondarily induced phenomenon after a long-standing disease process.

A patient with mitochondrial myopathy associated with isolated succinate dehydrogenase deficiency

We report on a boy with normal mental development who had muscle hypotonia and congenital dislocation of the hip and knee joints. Histochemical and biochemical examinations of his muscle specimen revealed no succinate dehydrogenase (SDH) activity. Since the NADH cytochrome c reductase and cytochrome c oxidase activities were normal, we concluded that he had an isolated SDH deficiency. Our patient provides further evidence for the clinical variability of this disorder.

Mitochondrial DNA mutations in Leigh syndrome and their phylogenetic implications

Of 100 patients with the clinical diagnosis of Leigh syndrome, 21 were found to have specific enzyme defects: 15 involving cytochrome c oxidase (COX); 4, pyruvate dehydrogenase complex (PDHC); one, complex I (reduced nicotinamide adenine dinucleotide [NADH]-coenzyme Q reductase) and one, complex II (succinate-ubiquinone reductase) deficiencies. In addition to the most common form of COX deficiency, mtDNA mutations in the adenosine triphosphatase (ATPase) 6 coding region were also commonly seen. Eighteen patients (18%) had mtDNA mutations at nucleotide position (np) 8993 or 9176. The mutated DNAs were present in a heteroplasmic state, comprising more than 90% of the DNA in muscle and/or blood samples from all patients. Patients with the T-to-G mutation at np 8993 usually had early onset of the disease with rapid progression, showing the typical clinical features of Leigh syndrome. On the other hand, those with the T-to-C 8993 mutation showed a milder and more chronic course. Patients with the mutation at np 9176 showed variable courses. Phylogenetic analysis of mtDNA D-loop sequences for the patients with the ATPase 6 mutations and normal Japanese subjects revealed that a T-to-G/C mutation at np 8993 and a T-to-C mutation at np 9176 occurred many times independently in the Japanese population.

[Preliminary report: first identification of known mutation in the ryanodine receptor gene in a Japanese malignant hyperthermia pedigree]

In Japan, the rate of Ca-induced Ca release (CICR) using skinned fibers of skeletal muscle has been employed as a diagnostic test for malignant hyperthermia (MH) susceptibility, since most of the typical fulminant MH patients showed an enhancement of CICR rate. Recently the Ca releasing channel responsible for the CICR was reported to be mainly the ryanodine binding Ca protein which was identified as the causative site of MH muscle according to recent genetic studies. Among patients with enhanced CICR rate, one point mutation for Arg 2434 His was recognized in a family. Although this site is related to the central core disease (CCD), this pathological change could not be observed in this patient. This is the first report describing a gene mutation in a MH family identified in Japan.

A novel congenital myopathy with apoptotic changes

We report on a female child with congenital myopathy with delayed developmental milestones and mental retardation. The most striking pathological finding was the presence of many condensed to fragmented myonuclei. DNA fragmentation was confirmed by the TUNEL method and supported by the ultrastructural characteristics of apoptotic nuclear changes. We also demonstrated immunohistochemically the activation of caspase-3 and caspase-9. This appears to be the first reported case of congenital myopathy with apoptotic process.

[A case of riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (glutaric aciduria type II)]

We reported a male infant with multiple acyl CoA dehydrogenase deficiency, probably due to electron transfer flavoprotein dehydrogenase deficiency. He was noted to have severe muscle weakness, a high serum creatine kinase (CK) level up to 6920 IU/L, lipid storage myopathy and fatty liver at 6 months of age. A GC/MS analysis of urinary organic acids showed excess excretion of dicarboxylic acids, including glutaric, 2-hydroxyglutaric, adipic, suberic, sebacic, malonic, ethylmalonic and methylsuccinic acids. On a urinary acylglycine analysis, hexanoylglycine and suberylglycine were increased, but not isovalerylglycine, in amount. No ketosis was noted. The muscle pathology showed increased oil-red O positive lipid droplets of various sizes indicative of lipid storage myopathy. There was diffuse decrease in the activity of cytochrome c oxidase. No ragged-red fibers were noted. His clinical symptoms improved remarkably after the administration of riboflavin (100 mg/day) and L-carnitine (1000 mg/day). He was then diagnosed as having probable riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency. The glutaryl CoA dehydrogenase activity in lymphocytes was normal, as were the alpha- and beta-subunits of electron transfer flavoprotein. These findings led us to suspect electron transfer flavoprotein dehydrogenation deficiency. Although he had several episodes of short-term deterioration in clinical and laboratory findings, he developed normally with normal intelligent till 10 years of age.

[Lysosomal glycogen storage disease with normal acid maltase (Danon) without apparent cardiomyopathy and mental retardation]

A 29-year-old male who had a past history of mild ECG abnormality of arrhythmia at the age of 14 years, was referred to our hospital because of elevated serum creatine kinase (CK) level. He had never been aware of muscular weakness nor cardiac symptoms. Neurological examination revealed normal muscle strength of all extremities except marked back muscle weakness. He had normal intelligence. On laboratory examination, serum AST, ALT, LDH, aldolase, CK and myoglobin levels were elevated. Both lactate and pyruvate levels were normally responded after an ischemic exercises test. Acid maltase activity was normal in white blood cells. A muscle biopsy obtained from rectus femoris muscle revealed vacuolar myopathy with mildly increased PAS positive material. On electron microscopy, there were autophagic vacuoles scavenging glycogen particles and cytoplasmic debris, and sarcolemmal indentation, compatible with the findings of lysosomal glycogen storage disease with normal acid maltase. This patient had unusual clinical features of absent mental retardation and no apparent cardiomyopathy. Accordingly, mental retardation is probably not necessary to see later onset of cardiac muscle involvement.

Oculopharyngeal muscular dystrophy in a Japanese family with a short GCG expansion (GCG)(11) in PABP2 gene

Clinicopathological and molecular genetic findings on a new Japanese family with oculopharyngeal muscular dystrophy are reported. The family has 54 members, ten of whom are affected (seven male and three female), in 3 generations. Three affected males, one affected female and one unaffected female of seven living siblings in the third generation were examined. Bilateral ptosis developed in the 4th and 5th decades in the three male cases, and in the 7th decade in the female, and this was followed by diplopia, nasal voice, dysphagia and muscle weakness. In addition, severe external ophthalmoplegia, dysphonia, and proximal amyotrophy were prominent in this family. Electromyographs revealed myogenic/neurogenic changes, and computed tomography disclosed selective muscle wasting with fatty replacement, predominantly in the lower extremities. Muscle biopsy in the four affected patients showed variation in fiber size, and the presence of small angulated fibers and occasional rimmed vacuoles. Electron microscopic examination revealed an accumulation of filamentous inclusions in muscle fiber nuclei. DNA analysis identified that (GCG)(6) in the PABP2 gene was expanded to (GCG)(11) in the four affected cases examined. All studies were negative in the one unaffected. These results confirm that OPMD is caused by GCG short expansion and provides insights into the genetic mechanisms which may contribute to adult onset myopathy, confined to oculopharyngeal muscles.

Histochemical responses of human soleus muscle fibers to long-term bedrest with or without countermeasures

Effects of 2- or 4-month bedrest in -6 degrees head-down tilt position with or without countermeasures on the histochemical properties of fiber phenotype and cross-sectional area (CSA) were studied in human soleus. The CSAs in slow fibers decreased approximately 32% during 4-month bedrest. This reduction was normalized after 1-month recovery. Although the reduction of percent slow fibers was not significant statistically, the percent intermediate fibers was significantly elevated 4 months after bedrest. Such shift in fiber type was not normalized following 1-month recovery. Effects of wearing an anti-g Penguin suit which has a modest, but continuous resistance at the knee and ankle (Penguin-1) or with knee resistance without loading on the ankle (Penguin-2) for 10 consecutive hours daily were also investigated during approximately 2 months of bedrest. The subjects performed knee extension and flexion for the last 15 min of each hour while in a supine position in bed. Bedrest-induced fiber atrophy was prevented in the Penguin-1 group but not the Penguin-2 group. Transformation of fiber type was not prevented in either Penguin suit group. It is suggested that long-term bedrest causes an atrophy and a shift of fiber phenotype toward fast-twitch type in human soleus. Data also indicated that loading on the muscle is an effective countermeasure for prevention of fiber atrophy but not fiber-type transformation.

Necrotizing myopathy in a patient with chronic hepatitis C virus infection: a case report and a review of the literature

We describe a 61-year-old man presenting with necrotizing myopathy associated with chronic active hepatitis due to hepatitis C virus (HCV) infection. Thirteen patients with HCV-associated myopathy have been reported previously. In most of these cases, varying degrees of inflammatory changes were observed in the muscle tissue. In 2 patients, myopathy developed after initiation of interferon therapy for chronic HCV hepatitis. Our case was unusual due to long-standing elevation of creatine kinase values which improved following interferon therapy and the non-inflammatory features of the muscle tissue where the HCV RNA minus strand, a marker for replicative intermediates of the virus, was undetectable. The association of myopathy with HCV infection might represent a unique clinical entity, although the underlying pathological mechanisms remain unknown.

Glycogen storage myopathies

The glycogen storage myopathies are caused by enzyme defects in the glycogenolytic or in the glycolytic pathway affecting skeletal muscle alone or in conjunction with other tissues. The authors review recent findings in this area, including a new entity, aldolase deficiency, and the wealth of molecular genetic data that are rapidly accumulating. Despite this progress, genotype-phenotyp3 correlations are still murky in most glycogen storage myopathies.

Genetic heterogeneity in three Chinese children with Fukuyama congenital muscular dystrophy

Three Chinese patients, two boys and one girl, were afflicted with the typical clinical, myopathological and neuroradiological findings of Fukuyama congenital muscular dystrophy (FCMD). Polymorphism analysis of our patients did not reveal the founder haplotype (138-192-147-183 in D9S2105-D9S2170-D9S2171-D9S2107) of Japanese FCMD, even though one patient was descended from Japanese ancestry. Full mutational analysis of the fukutin gene revealed that there is neither 3 kb insertion nor point mutation. These findings suggest genetic heterogeneity between Chinese and Japanese FCMD patients.

Mutations of calpain 3 gene in patients with sporadic limb-girdle muscular dystrophy in Japan

Mutations of the calpain 3 gene, an intracellular calcium-activated neutral protease, is one of the causes of limb-girdle muscular dystrophy (LGMD). We examined 14 Japanese patients with sporadic LGMD for calpain 3 mutations, and found four mutations in five patients. Three (R461C, D707G and R147P) were novel missense mutations, and one was a splice-site mutation (801+1g-->a) resulting in skipping of exons 4 and 5. Of the five patients, three patients with homozygous missense mutations showed later onset and slower progression than the other two patients with an exon skipping or mRNA loss of unknown cause. It would appear that the occurrence of calpain 3 gene mutations in sporadic LGMD in Japan may be quite high since all five patients with mutations in this gene were among the 14 patients without apparent family history, an incidence of 36%. These findings also suggest that calpain 3 deficiency occurs in both sporadic and familial LGMD and that direct analysis of the calpain 3 gene may be useful in the definitive diagnosis not only of the 15q-linked familial but also of sporadic cases of LGMD.

Myonuclear domain and myosin phenotype in human soleus after bed rest with or without loading

After 2 or 4 mo of bed rest (6 degrees head-down tilt) and 1 mo of ambulation, there was a tendency toward a higher percentage of fibers expressing fast myosin heavy chain (MHC) isoforms and a de novo appearance of fibers coexpressing type I+IIa+IIx and IIa+IIx MHC in human soleus fibers. After 2 and 4 mo of bed rest, the mean size of type I fibers decreased by 12 (P > 0.05) and 39%, respectively. Because myonuclear number/mm of fiber length was unchanged, myonuclear domain was smaller after bed rest than before. The mean size and myonuclear domain of type I fibers were largest after 1 mo of recovery. The effects of wearing an antigravity device (Penguin suit), which had a modest but continuous resistance at the knee and ankle (Penguin-1) or knee resistance without loading on the ankle (Penguin-2), for 10 consecutive h/day were determined during 2 mo of bed rest. Mean fiber sizes in Penguin-1, but not Penguin-2, group were maintained at or above pre-bed-rest levels, whereas neither group showed phenotype changes. Myonuclear domain in type I fibers was larger in Penguin-1 and smaller in Penguin-2 group post- compared with pre-bed rest, indicating that a single daily 10-h bout of modest muscle loading can prevent bed-rest-induced soleus fiber atrophy but has minimal effect on myosin phenotype. The specific adaptive cellular strategies involved may be a function of the duration and magnitude of the adaptive stimulus as well as the immediate activity history of the fiber before the newly changed functional demands.

Distal myopathies

Among various previously described distal myopathies, several diseases have now been established as clinically and genetically distinct entities. The most representative diseases are dominantly inherited Welander distal myopathy and tibial muscular dystrophy, and the recessively inherited distal myopathy with rimmed vacuoles and distal muscular dystrophy (Miyoshi myopathy). Since the discovery of the gene loci for several distal myopathies, several diseases previously categorized as different disorders have now proven to be the same or allelic disorders (e.g. distal myopathy with rimmed vacuoles and hereditary inclusion body myopathy, Miyoshi myopathy and limb-girdle muscular dystrophy with gene locus at 2p13). Except for Miyoshi myopathy, which has the typical findings of muscular dystrophy, most of the distal myopathies share the common pathologic features of myopathic changes with rimmed vacuoles. The pathologic changes are somewhat similar to those seen in chronic muscular dystrophy, but necrotic and regenerative processes are less prominent and creatine kinase levels are either normal or only mildly elevated. Further study is necessary to determine why rimmed vacuoles are so common in the distal myopathies, and what role they play in the pathogenesis of muscle fibre atrophy and loss, predominantly in the distal portions of the extremities.

[A sporadic case of Charcot-Marie-Tooth disease type 1 A associated with a duplication in chromosome 17 p11.2-p12]

Charcot-Marie-Tooth disease type 1A (CMT1A) is an autosomal dominant demyelinating peripheral neuropathy. Most patients with CMT1A including sporadic cases have been found to have a 1.5 megabase tandem DNA duplication in chromosome 17 p11.2-p12 (CMT1A duplication). We reported a 7-year-old girl with sporadic CMT 1 associated with the CMT1A duplication. The diagnosis of CMT 1 was based on the symmetrical distal muscle weakness, per cavus deformity, reduced motor and sensory nerve conduction velocities, and segmental de- and remyelinatin on sural nerve biopsy. To detect the CMT 1A duplication, peripheral myelin protein 22 (PMP-22) cDNA and a polymorphic marker in this region, VAW409 R3, were employed as probes for Southern blot analysis. Sporadic cases of autosomal dominant-CMT type 1 can not be clinically differentiated from recessive-CMT1. Testing for the CMT1A duplication is an important first step even in the molecular diagnosis of sporadic CMT1.

[A patient of Walker-Warburg syndrome with a haplotype different from that in Fukuyama-type congenital muscular dystrophy]

A 3-month-old female baby was diagnosed as having Walker-Warburg syndrome (WWS), based on the following clinical findings: type II lissencephaly associated with marked ventricular dilatation, cerebellar malformation, retinal malformation, elevated serum creatine kinase level and abnormal muscle CT findings. She was a product of parents with consanguineous marriage. She presented with severe hypotonia and profound psychomotor retardation since birth. She developed infantile spasms at 8 months of age, and vitamin B6 was very effective. A genetic analysis revealed the absence of the founder haplotype commonly seen in Fukuyama-type congenital muscular dystrophy (FCMD), suggesting that the WWS gene is not always identical to the FCMD gene. When she was examined at the age of 4 years, she had no apparent further psychomotor development. Her clinical symptoms were more severe than those of the typical FCMD.

[Hepatic involvement in a case of lysosomal glycogen storage disease with normal acid maltase]

A 19-year-old man, who could run only slowly since childhood and who walked on his toes since 12 years of age, noted difficulty in climbing upstairs at 17 years of age. He was admitted to Kyushu University Hospital because of elevated AST, ALT and CK levels. On admission, the liver was palpable two fingerbreadths beneath the right costal margin. A neurological examination revealed a low IQ on WAIS-R, a decreased muscle tonus in his four limbs, moderate weakness of the neck flexor and bilateral tibialis anterior muscles, contracture of the ankle joints, and bilateral pes cavus. The serum CK was elevated to 1,124U/l. Hepatic enzymes, such as AST, ALT, LDH and gamma-GTP were also moderately increased in the sera. A needle EMG disclosed myogenic patterns in the limb muscles. Biopsied biceps brachii muscle showed a mild variation in the fiber size and multiple tiny vacuoles in 5-10% of the muscle fibers. PAS and acid phosphatase were strongly positive in some vacuoles. On electron microscopy, numerous autophagic vacuoles containing glycogen granules were observed. The acid maltase activities were, however, normal in the peripheral blood lymphocytes, the biopsied muscle, and the cultured skin fibroblasts. He was thus diagnosed to have lysosomal glycogen storage disease with normal acid maltase. A histological examination of the biopsied liver revealed the portal and central veins to be slightly sclerotic. In addition, mild fatty changes and frequent nuclear vacuolization were present in the hepatocytes. On electron microscopy, enlarged mitochondria with irregular cristae were also observed. Due to the fact that the cardiac function was well preserved, these hepatic lesions were thought to result from the metabolic abnormalities underlying in this disorder.

Transforming growth factor-beta2 is elevated in skeletal muscle disorders

The transforming growth factor betas (TGF-betas) are multifunctional growth factors that act on both fibroblasts and myosatellite cells. In rodent models of muscle diseases, high levels of TGF-beta2 are expressed by myogenic cells. We have examined whether the expression of TGF-beta2 is also elevated in diseased human muscles. The disorders examined were Duchenne muscular dystrophy, myotonic dystrophy, myotubular myopathy, spinal muscular atrophy, and amyotrophic lateral sclerosis. The levels of TGF-beta2 immunoreactivity were elevated in atrophic, necrotic, and regenerating fibers and in fibers with central nuclei or cytoplasmic masses, irrespective of whether fibrosis was present. We therefore suggest that TGF-beta2 is important for muscle repair and that the presence of a TGF-beta within a muscle only leads to fibrosis if certain other factors are present.

A case of McLeod syndrome with unusually severe myopathy

A 51-year-old man developed weakness and muscle atrophy in the legs at the age of 41, later followed by choreiform involuntary movements. Neurological and laboratory examinations revealed severe muscle weakness and atrophy, and areflexia in all the extremities, acanthocytosis and an elevated serum creatine kinase level. Together with these findings, the weak expression of Kell blood group antigens and the absence of the Kx antigen led to a definite diagnosis of McLeod syndrome for his condition. Brain magnetic resonance imaging revealed marked atrophy of the head of the caudate nuclei. Although immunocytochemical analysis of dystrophin in muscle specimens from our patient revealed normal staining, we found prominent fiber size variability, central nuclei, and connective tissue proliferation as well as necrotic and regenerating fibers, which are as a whole compatible with the myopathology of muscular dystrophy. Moreover, muscle computerized tomography of the lower extremities revealed the 'selectivity pattern' characteristically reported in muscular dystrophies including Duchenne type muscular dystrophy. The muscular symptoms and pathology in McLeod syndrome have been reported to be mild, but the present case clearly shows that the muscular features in this condition may be much more severe than previously thought.

Early onset of X-linked Emery-Dreifuss muscular dystrophy in a boy with emerin gene deletion

A boy developed contractures of the Achilles tendons at 3 years and of the postcervical muscles at 7 years, although neither contractures of the elbows nor cardiac abnormality were recognized by the age of 9 years. Muscle computed tomography scanning revealed changes characteristic of muscle involvement. Emerin was not detected in the biopsied muscle, and RT-PCR and PCR-based genomic DNA analyses of the emerin gene demonstrated no amplification product in the patient. These results confirmed the diagnosis of X-linked Emery-Dreifuss muscular dystrophy (EDMD), and reinforce the necessity of molecular genetic diagnosis of the membrane protein emerin in younger patients with possible EDMD before appearance of the typical symptoms, to avoid sudden cardiac death.