Systemic muscular inflammation in a patient with recurrent orbital myositis.

We report a 53-year-old Japanese woman who had recurrent orbital myositis for 14 years. She exhibited mild muscle weakness in proximal limbs 13 years after the onset of orbital myositis. An electromyogram revealed myopathic potentials and denervation potentials in proximal limb muscles. Quadriceps biopsy showed infiltrates of mononuclear cells around intramuscular vessels and mild degenerative changes in muscle cells. These findings indicate that the present case belongs to the spectrum of localized nodular myositis.

Dermatomyositis associated with impairment in both muscle aerobic and anaerobic function.

We report a 50-year-old Japanese woman with dermatomyositis in whom an anti-mitochondrial antibody was detected. Muscle biopsy demonstrated periodic acid Schiff- (PAS) positive vacuoles in addition to infiltrates of mononuclear cells. Histochemical analysis showed reduced phosphorylase activity. An aerobic exercise test demonstrated that the concentrations of serum lactate and pyruvate were elevated before corticosteroid therapy but decreased after the therapy. On the other hand, in forearm ischemic exercise tests, the responses of serum lactate and pyruvate were attenuated before corticosteroid therapy but recovered after the therapy. These findings indicate that an inflammatory mechanism interfered with myophosphorylase activity and muscle aerobic function.

Dermatomyositis associated with Sjögren's syndrome: VEGF involvement in vasculitis.

Two patients with dermatomyositis complicated with Sjögren's syndrome (SjS), are reported. Both patients exhibited sensory-dominant polyneuropathy, compatible with neurologic involvement in SjS. Vascular endothelial growth factor (VEGF) levels were increased in their plasma. Histological examination demonstrated vasculitic changes in biopsied specimens of muscle and salivary glands from the patients, and VEGF was overexpressed in the vasculitic lesions. These findings suggest that VEGF overexpression was associated with the development of vasculopathy in skeletal muscle and salivary glands and possibly in the peripheral nervous system.

Central motor conduction in patients with anti-ganglioside antibody associated neuropathy syndromes and hyperreflexia.

OBJECTIVES: Several serum antibodies against gangliosides are diagnostically important, particularly in Guillain-Barré syndrome (GBS), Miller Fisher syndrome (MFS), and multifocal motor neuropathy (MMN). Although hyperreflexia is an atypical symptom in these disorders, it has been found in some patients with GBS, MFS, and MMN. The aim of the study was to determine whether hyperreflexia corresponds to corticospinal tract dysfunction in these patients. METHODS: The study examined central and peripheral motor conduction in patients with hyperreflexia who exhibited acute paralysis (group 1, n=5), acute ataxia and ophthalmoplegia (group 2, n=7), or chronic paralysis with conduction block (group 3, n=2). The clinical symptoms are similar to those in patients with GBS, MFS, and MMN, respectively, and serum anti-ganglioside antibodies were found to be positive in all patients. Using magnetic and electrical stimulation techniques, central and peripheral motor conduction were compared in patients in groups 1, 2, and 3 and patients with GBS (n=7), MFS (n=8), and MMN (n=6). RESULTS: Central motor conduction times (CMCTs) in patients in groups 1, 2, and 3 were significantly delayed compared with those in patients with GBS, MFS, and MMN (p<0.01, p<0.05, p<0.05, respectively), and the delayed CMCTs significantly improved in the recovery periods (p<0.01, p<0.01, p<0.05, respectively). However, motor conduction velocity, compound muscle action potential, and F wave conduction velocity were not significantly different between the patients. CONCLUSION: These findings indicate that corticospinal tract is functionally involved in patients with anti-ganglioside antibody associated neuropathy syndromes and hyperreflexia

Mutation frequency is reduced in the cerebellum of Big Blue mice overexpressing a human wild type SOD1 gene.

Amyotrophic lateral sclerosis (ALS) is a progressive paralytic disorder caused by motor neuron degeneration. A similar disease phenotype is observed in mice overexpressing a mutant human hSOD1 gene (G93A, 1Gurd(1)). Mice transgenic for lacI (Big Blue) and human mutant (1Gurd(1), Mut hSOD1) or wild type (2Gur, Wt hSOD1) SOD1 genes were used to examine spontaneous mutation, oxidative DNA damage, and neurodegeneration in vivo. The frequency and pattern of spontaneous mutation were determined for forebrain (90% glia), cerebellum (90% neurons) and thymus from 5-month-old male mice. Mutation frequency is not elevated significantly and mutation pattern is unaltered in Mut hSOD1 mice compared to control mice. Mutation frequency is reduced significantly in the cerebellum of Wt hSOD1 mice (1.6x10(-5); P=0.0093; Fisher's Exact Test) compared to mice without a human transgene (2.7x10(-5)). Mutation pattern is unaltered. This first report of an endogenous factor that can reduce in vivo, the frequency of spontaneous mutation suggests potential strategies for lowering mutagenesis related to aging, neurodegeneration, and carcinogenesis.

Functional association between nicotinic acetylcholine receptor and sarcomeric proteins via actin and desmin filaments.

By affinity chromatography utilizing alpha-cobrotoxin from digitonin-solubilized fractions of rabbit skeletal muscle, we found that many proteins are associated with the nicotinic acetylcholine receptor (AChR). In addition to the proteins we previously reported to bind to AChR (including dystrophin-dystrophin-associated protein (DAP) complex, utrophin, rapsyn, and actin; Mitsui et al. [1996] Biochem. Biophys. Res. Commun.224:802-807), alpha-actinin, desmin, myosin, tropomyosin, troponin T, and titin are also identified to be associated with AChR. Alkaline treatment or Triton X-100 solubilization released dystrophin-DAP complex, utrophin, and rapsyn from the AChR fraction, while actin and desmin remained associated. These findings demonstrate that AChR is supported primarily by a submembranous organization of actin and desmin filaments, and is linked to sarcomeric proteins via these filaments. To further investigate whether the association has any functional role, we studied the effect of acetylcoline on ATPase activity of the AChR fraction. Acetylcholine (0.5-4 microM) significantly activated Mg(2+)-ATPase activity of digitonin-solubilized AChR fraction (P < 0.05). Furthermore, we found that desmin as well as actin activated myosin Mg(2+)-ATPase activity. From these findings, it is suggested that desmin and actin form a submembranous organization in the postsynaptic region, and function as mediators of excitation of AChR to the sarcomeric contraction system.