Anti-neuronal antibodies in acute pandysautonomia

We encountered two patients with acute pandysautonomia who subacutely exhibited extensive autonomic dysfunction after antecedent infections. Although these patients had been suffering from autonomic disturbance for several months, they both had a good clinical course after plasma exchange and intravenous immunoglobulin therapy. Thin-layer chromatography (TLC)-immunostaining did not demonstrate any antibodies against gangliosides, but immunoblot analysis showed antibodies against a neuroblastoma cell line, SH-SY5Y, in serum samples. Furthermore, ganglionic acetylcholine receptor autoantibodies were detected in one patient. These findings suggest that neuronal antibodies against the autonomic nervous system play an important role in the pathogenesis of acute pandysautonomia.

Cardiac dysfunction in patients with chronic progressive external ophthalmoplegia

BACKGROUND

Chronic progressive external ophthalmoplegia (CPEO), which includes Kearns-Sayre syndrome, is a mitochondrial disorder with large deletions of mitochondrial DNA. Recently, mtDNA deletions in cardiac muscle cells were thought to be a cause of dilated cardiomyopathy. However, the cardiac involvement in patients with CPEO is generally considered to be limited to the cardiac conduction system.

HYPOTHESIS

The purpose of this study was to evaluate left ventricular function in patients with CPEO.

METHODS

We evaluated the cardiac function of five patients with CPEO by means of carotid pulse recording and Doppler echocardiography.

RESULTS

The ratio of the pre-ejection period to ejection time was increased to 0.67 in one patient and to 0.50 in another. Echocardiography showed left ventricular dilatation and diffuse hypokinetic wall motion in both cases. Left ventricular fractional shortening was decreased to 5 and 19%, respectively, and the mean rate of circumferential shortening was decreased to 0.12 and 0.63 circ/s, respectively. One of the two patient died of congestive heart failure 2 months after the study. The Doppler pattern of left ventricular filling in the three remaining patients showed a decrease in the ratio of peak flow velocity in early diastole to that in late diastole, with an increase in deceleration time.

CONCLUSION

Although cardiac involvement in patients with CPEO is generally considered to be limited to the cardiac conduction system, left ventricular dysfunction may be present and should receive more attention in the management of patients with CPEO.

Beneficial Effect of Tacrolimus on Myasthenia Gravis With Thymoma

We examined the effect of tacrolimus on myasthenia gravis (MG). Five patients with thymoma and 5 patients without thymoma underwent prior thymectomy but showed persistent myasthenic symptoms. Oral administration with tacrolimus significantly improved MG scores 1, 3, and 6 months following the beginning of treatment in all patients (P < 0.05), and the improvement was significantly higher in the thymoma group compared with the nonthymoma group (P < 0.05). However, there was no significant change in antiacetylcholine receptor titers in either group. This indicates a particular application of immunosuppressive therapy for thymomatous MG following thymectomy.

Parkin affects mitochondrial function and apoptosis in neuronal and myogenic cells

We investigated the effect of parkin on mitochondrial function and apoptosis in SH-SY5Y, L6, RD, and COS-1 cells. Wild-type parkin attenuated reactive oxygen species (ROS) production in SH-SY5Y cells and mutant parkin enhanced ROS production in SH-SY5Y and L6 cells. Reactive oxygen intermediates, that were detected in mitochondria, were decreased in cells with overexpression of parkin. Parkin prevented apoptosis and enhanced mitochondrial membrane potentials in SH-SY5Y and L6 cells not in COS-1 cells. Expressions and enzymatic activities of mitochondrial respiratory chain complexes were not uniformly enhanced but those of complex 1 were selectively enhanced. The present results suggest the cell-selective function of parkin, i.e., parkin possesses anti-apoptotic and anti-oxidant function in neuronal or myogenic cells but not in kidney cells.

Parkin enhances mitochondrial biogenesis in proliferating cells

We describe a novel function of parkin, a RING protein, which is elaborately involved in mitochondrial biogenesis. Parkin was located within the mitochondrial organelle of proliferating cells. Anti-proliferative treatments released parkin from mitochondria to cytosol. Results of pharmacological treatments indicate that parkin was released from mitochondria when permeability transition pore was opened. The extra-mitochondrial localization was also observed in differentiated cells. In proliferating cells, transcription and replication of mitochondrial DNA was enhanced by parkin overexpression and attenuated by parkin suppression with siRNA. Parkin was associated with mitochondrial transcription factor A (TFAM) and enhanced TFAM-mediated mitochondrial transcription. These results indicate that parkin is involved in the regulation of mitochondrial transcription/replication other than the ubiquitin-mediated protein degradation system in proliferating cells.

Delayed motor and sensory neuropathy in a patient with brainstem encephalitis

Bickerstaff's brainstem encephalitis (BBE), Miller Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS) are thought to be closely related and to form a continuous spectrum. However, chronic polyneuropathy in BBE has not been reported. We report the temporal profile of anti-ganglioside antibody titer in a case of BBE-like brainstem encephalitis complicated with chronic polyneuropathy. A 71-year-old Japanese woman presented with drowsiness and cerebellar ataxia in addition to mild weakness in distal limb muscles. Anti-GalNAc-GD1a IgG and anti-GalNAc-GM1b IgG antibodies were positive in her serum. Brain magnetic resonance imaging revealed high-intensity signals in the midbrain, pons, and middle cerebellar peduncles on T2-weighted images. Central nervous system manifestations improved after immunomodulating therapy that included prednisolone, plasmapheresis and intravenous immunoglobulin. Nevertheless, the distal muscle weakness was exacerbated when the anti-GalNAc-GD1a IgG titer was elevated. Nerve conduction study indicated motor and sensory neuropathy which was developed motor dominant axonal damage. These findings suggest that anti-ganglioside antibodies, including anti-GalNAc-GD1a IgG, may be involved in a common autoimmune mechanism in BBE-like brainstem encephalitis and chronic motor dominant axonal neuropathy. However, the fact that the latter manifestation exacerbated after the improvement of former one possibly indicates different thresholds of neurologic symptoms mediated by anti-ganglioside antibodies in the present patient.

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.

Involvement of mitochondria in myasthenia gravis complicated with dermatomyositis and rheumatoid arthritis: a case report

We report a 57-year-old male with myasthenia gravis complicated with dermatomyositis and rheumatoid arthritis without evidence of thymoma. He showed prominent muscle wasting and weakness in the four extremities and trunk in addition to swallowing disturbance. He showed intolerance to exercise on a bicycle ergometer, and muscle biopsy specimens demonstrated ragged-red fibers. An anti-acetylcholine receptor (AChR) antibody was detected in his serum but no anti-mitochondrial M2 component antibody was found. In contrast, results of immunohistochemical study indicated that his serum sample reacted to muscle mitochondria as well as AChR. These results indicate the presence of an unidentified anti-mitochondrial antibody that may be involved in the development of mitochondrial dysfunction in skeletal muscle of the present patient.

Central motor conduction in cervical dystonia with cervical spondylotic myelopathy

OBJECTIVES

It has been known that cervical dystonia develops secondarily to spinal cord injuries as secondary dystonia. However, little is known about the pathophysiological mechanism.

PATIENTS AND METHODS

We examined motor and sensory conduction in six patients with symptomatic cervical dystonia by transcranial magnetic stimulation (TMS). All of the patients exhibited unilateral head rotation. They had symptoms corresponding to cervical myelopathy and felt discomfort in the neck, shoulders or arms before involuntary movement occurred.

RESULTS

Although the overall central motor conduction time (CMCT) was not different from that of normal controls, contralateral CMCT was significantly delayed compared to ipsilateral CMCT (p<0.05). The results of somatosensory evoked potential study demonstrated that contralateral central conduction time (CCT) was not significantly different from ipsilateral CCT.

CONCLUSION

These findings indicate that there is a selective interference with the contralateral corticospinal tract in patients with symptomatic cervical dystonia.

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.

Guillain-Barré syndrome and hemophagocytic lymphohistiocytosis in a patient with severe chronic active Epstein-Barr virus infection syndrome

Epstein-Barr virus (EBV) infection causes a wide range of neurologic and hematologic manifestations. We report a 72-year-old Japanese male patient with severe chronic active EBV infection syndrome (SCAEBV) who presented with Guillain-Barré syndrome (GBS) and developed hemophagocytic lymphohistiocytosis (HLH) several months after the onset of GBS. He showed acute onset of distal muscle weakness, ophthalmoplegia and bulbar palsy. Results of nerve conduction study revealed acute motor-sensory axonal neuropathy (AMSAN). His serum was positive for anti-LM1 IgG and anti-GM1b IgM. Titers of antibodies to EBV-related antigens indicated chronic reactivated EBV infection. Treatment with IVIg resolved the acute ophthalmoplegia, but there was no notable improvement in the AMSAN and bulbar palsy despite repeated. Finally, he developed refractory HLH resulting in a fatal outcome. In the present patient, it seems that SCAEBV was associated with the development of GBS and fatal HLH via parainfectious autoimmunity and direct infectious immune mechanisms, respectively.

Isolated cranial neuropathy associated with anti-glycolipid antibodies

We describe seven patients with isolated cranial neuropathy in whom serum anti-glycolipid antibodies were detected. Trigeminal sensory neuropathy was found in four patients, who had exhibited symptoms for 2 months to 4 years. The other three patients showed facial nerve palsy with or without ophthalmoparesis. Temporal profile analysis of anti-glycolipid antibodies revealed that titers of anti-glycolipid IgM antibodies against GM2 and LM1 gradually decreased in patients having chronic trigeminal sensory neuropathy. In patients with acute trigeminal sensory neuropathy, elevation of anti-LM1 antibody titers continued over 12 months although anti-GalNAc-GD1a antibody disappeared. On the other hand, titers of anti-glycolipid antibodies rapidly decreased in patients with acute facial nerve palsy with or without ophthalmoparesis. We conclude that anti-glycolipid antibodies may play an important role in the development of isolated cranial neuropathy in some patients.

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.

Neuro-Beh�et?s disease with chorea after remission of intestinal Beh�et?s disease

Neuro-Behçet's disease shows various neuropsychiatric symptoms, but chorea has rarely been reported. We report a case of neuro-Behçet's disease in a 67-year-old woman with depression and chorea that occurred 22 years after the onset of intestinal Behçet's disease. Brain magnetic resonance imaging (MRI) using a fluid-attenuated inversion-recovery (FLAIR) sequence demonstrated lesions more clearly than did T2-weighted MRI. Some of the lesions appeared as small ring-like foci, i.e. low-intensity spots rimmed with remarkable hyperintense signals, in the periventricular white matter and basal ganglia. A review of the literature revealed that the onset of chorea in cases of Behçet's disease varied from the time of onset of Behçet's disease to 31 years after onset of the disease. Psychiatric manifestations have often been associated with neuro-Behçet's disease. In the present patient, treatment with prednisolone resolved the chorea, suggesting that the chorea was caused by an autoimmune mechanism. It seems likely that the long-term development of vasculitis in patients with Behçet's disease results in the formation of these particular brain lesions on FLAIR MR images. Chorea should be taken into consideration as one of the manifestations of Behçet's disease, even many years after remission of the disease.

Complicated paraneoplastic neurological syndromes: a report of two patients with small cell or non-small cell lung cancer

Paraneoplastic neurological syndromes are frequently associated in patients with small cell lung cancer (SCLC) and antineuronal antibodies are involved in the autoimmune mechanism. Multiple syndromes are sometimes complicated in a single patient with SCLC. However, little is known about non-SCLC-associated neurological manifestations. We report two patients with complicated paraneoplastic neurological syndromes. Patient 1 showed paraneoplastic limbic encephalitis (PLE), paraneoplastic sensory neuropathy (PSN) and Lambert-Eaton myasthenic syndrome (LEMS) associated with SCLC. Patient 2 developed opsoclonus-ataxia and probable PLE associated with non-SCLC. Analysis of various antineuronal antibodies revealed that anti-Hu and P/Q-type voltage-gated calcium channel (VGCC) antibodies were positive in Patient 1 but any antibodies were not in Patient 2. Brain MRI demonstrated high intensity signals in temporal lobes particularly on fluid-attenuated inversion recovery (FLAIR) or diffusion-weighted images. These findings suggest that complicated paraneoplastic neurological syndromes occur in non-SCLC as well as SCLC and that unidentified antineuronal autoantibodies may underlie the pathophysiology.

Spontaneous mutation in Big Blue mice from fetus to old age: tissue-specific time courses of mutation frequency but similar mutation types

Transgenic mouse mutation detection systems permit rapid determination of the frequency and type of mutations allowing direct examination of mutational markers for aging, neurodegeneration, and cancer. The Big Blue transgenic mouse mutation detection system was used to determine the frequency and nature of spontaneous mutations versus age in multiple tissue types. Nuclear DNA was extracted from whole fetus at 13.5 days postcoitus (dpc) and from six tissues postbirth (cerebellum, forebrain, thymus, liver, adipose tissue, and male germline) of Big Blue transgenic mice at four ages: 10 days and at 3, 10, and 25 months postbirth. Forty million total plaque-forming units (pfu) were screened. The time course of mutation frequency with age had a significantly different shape in different tissues (P < 10(-6)). By 13.5 dpc, the whole fetus mutation frequency had already started increasing from the theoretical zero at conception to a value that was about one-half the mid-adulthood (3-10 months) average. From 10 days to 3 months, mutation frequency increased significantly in liver (P = 0.007) and showed an increasing trend in cerebellum, forebrain, and thymus. From 3 to 10 months, there was no significant change in mutation frequency in any tissue examined. From 10 to 25 months, the mutation frequency increased significantly in liver (P < 10(-6)) and adipose tissue (P = 0.002), but not in the other tissues examined (cerebellum, forebrain, and male germline). It is of interest that the mutation frequency in the male germline is consistently the lowest, remaining essentially unchanged in old age. The spectrum of mutation types was unaltered with age, tissue type and gender, although, as previously reported, tandem GG-->TT mutations are tissue specific and show significant increases with age and certain hotspots (Buettner VL et al. [1999]: Environ Mol Mutagen 33:320-324; Hill KA et al. [2003]: Mutat Res 534:173-186). The spectrum of mutation types was generally the same for all tissue types, despite the tissue-specific increases in mutation frequency with age. These data provide a useful reference for future studies of endogenous and exogenous mutagenesis.

Oxidative stress-associated mitochondrial dysfunction in corticosteroid-treated muscle cells

We analyzed the effects of corticosteroid on mitochondrial membrane potentials (DeltaPsi(m)), generation of reactive oxygen species (ROS), and apoptosis in a human rhabdomyosarcoma cell line, RD, and a dopaminergic neuroblastoma cell line, SH-SY5Y. The cell lines were cultured in the presence or absence of dexamethasone and superoxide dismutase (SOD) for up to 1 week. Dexamethasone treatment increased DeltaPsi(m), ROS generation, and apoptosis in proliferating RD cells. Treatment with SOD attenuated ROS generation and apoptosis, but not DeltaPsi(m). The increase in DeltaPsi(m) seemed to be the primary effect of dexamethasone on proliferating RD cells, which is probably mediated by mitochondrial transcription. In differentiated RD cells, but not differentiated SH-SY5Y cells, dexamethasone treatment showed a delayed effect of interfering with the DeltaPsi(m) and increasing ROS generation and apoptosis. Since these changes disappeared in the presence of SOD, dexamethasone primarily induced ROS generation, resulting in apoptosis. We speculate that this mechanism provides the basis of a pathophysiological model of corticosteroid myopathy.

Dermatomyositis with peripheral nervous system involvement: activation of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) in vasculitic lesions

We describe two cases of dermatomyositis (DM) with nervous system involvement. Polyneuropathy was observed in both patients, and cerebral vasculitis was suspected in one patient. Histological examination of biopsied specimens of skeletal muscles, skin and sural nerves revealed vasculitis. Furthermore, vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) were overexpressed in vasculitic lesions. Although, VEGF and VEGFRs were not detected in biopsied specimens of skeletal muscle from normal subjects, they were observed in one of two patients with DM who did not exhibit neuropathy. These findings suggest the possibility that VEGF overproduction is associated with development of vasculitis in some cases of DM complicated with peripheral neuropathy.

Beneficial Effect of Steroid Pulse Therapy on Acute Viral Encephalitis

Corticosteroids are often used in the treatment of acute viral encephalitis, although the efficacy of corticosteroid therapy has not been proven. We examined the effects of high-dose corticosteroid therapy on acute viral encephalitis in 5 patients with progressive disturbances of consciousness. In 3 patients who were treated within 5 days after the onset of illness, pulse therapy dramatically reduced the degree of consciousness disturbance. They became alert within 24 h, and then neurological symptoms gradually improved. Corticosteroid therapy in the other 2 patients, in whom treatment was started more than 3 weeks after the onset of illness, was not as effective, but repeated therapy at 2-week intervals resulted in complete recovery. These findings suggest that high-dose corticosteroid therapy is effective, particularly for disturbances of consciousness, an important prognostic factor in acute viral encephalitis.

Overexpressions of myoglobin and antioxidant enzymes in ragged-red fibers of skeletal muscle from patients with mitochondrial encephalomyopathy

To determine the relationship between myoglobin (Mb) and the defense system against reactive oxygen species in various myopathies, we performed immunohistochemical analyses of Mb and various antioxidant enzymes, including manganese superoxide dismutase (Mn-SOD), copper zinc SOD (CuZn-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px). Biopsied muscle specimens were obtained from patients with chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayre syndrome (KSS), Duchenne muscular dystrophy (DMD), and polymyositis (PM). In patients with CPEO/KSS, stainings of Mb, SOD, CAT, and GSH-Px in nonatrophic ragged-red fibers (RRFs) were more intense than those in non-RRFs. These pronounced stainings corresponded to ragged-red lesions. The staining intensities of these antioxidant enzymes were significantly correlated with that of Mb (P < 0.001). Atrophic RRFs in specimens from patients with CPEO/KSS showed intense stainings of these antioxidant enzymes but not intense staining of Mb. In specimens from patients with DMD/PM, the antioxidant enzymes but not Mb were overexpressed in degenerative fibers. These results suggest that oxidative stress is associated with Mb expression specifically in mitochondrial diseases. The antioxidant enzymes seem to be upregulated to protect against muscle damage in nonatrophic RRFs. However, the Mb-mediated oxidative damage may become more extensive and result in further mitochondrial dysfunction and progressive atrophy of RRF with impaired upregulation of Mb.

Dissociation between titer of anti-ganglioside antibody and severity of symptoms in a case of Guillain-Barré syndrome with treatment-related fluctuation

Since plasma exchange (PE) and intravenous immunoglobulin (i.v.Ig) have been widely used in treatment for Guillain-Barré syndrome (GBS), early relapse and treatment-related fluctuation have been a potential problem, but little is known about the mechanism of relapse and fluctuation. We describe a patient who had GBS with treatment-related fluctuation. A 37-year-old Japanese man exhibited acute distal-dominant weakness in upper limbs after upper respiratory infection. His cranial nerve system was normal and muscle weakness was limited to upper limbs. Anti-GT1a IgG was strongly positive and anti-GQ1b IgG was also detected in his serum. Muscle weakness responded well to double-filtration plasmapheresis (DFPP) followed by i.v.Ig, but relapsed 45 days after the initial treatment. Although repeated treatments were effective, the patient showed additional minor deterioration twice. Motor nerve conduction velocities (MCVs) corresponded to the muscle weakness, but elevated level of cerebrospinal fluid (CSF) protein remained and anti-ganglioside antibody titers steadily decreased throughout the clinical course. These findings indicate that the clinical fluctuation was not due to changes in the production of anti-ganglioside antibodies but presumably to the transient beneficial effects of DFPP/i.v.Ig and the outlasting inflammatory response in peripheral nerves.

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.

Spontaneous mutation frequency and pattern in Big Blue mice fed a vitamin E-supplemented diet

Endogenous oxidative DNA damage caused by normal cellular processes may play a vital role in carcinogenesis. To directly test the hypothesis that antioxidants will protect DNA from oxidative damage in vivo, Big Blue((R)) mice were fed either a control diet (66 IU vitamin E/kg diet) or a high-dose vitamin E diet containing 1000 IU vitamin E/kg diet of racemic d,l-alpha-tocopherol acetate from conception until 3 months of age. Using the standard Big Blue((R)) protocol, 15.5 million plaque forming units (pfu) were examined from five tissues (heart, liver, adipose tissue, thymus, and testis) of three control and three high-dose vitamin E supplemented male mice generating 433 mutants, which represented 373 independent mutations upon sequencing the lacI transgene. The alpha-tocopherol tissue concentration increased with high-dose vitamin E supplementation. In four of the tissues, individually or combined, mutation frequency changed little if any with vitamin E supplementation. In adipose tissue, which accumulated the highest levels of vitamin E, mutation frequency was significantly reduced with high-dose vitamin E supplementation (P = 0.047). Within the constraints of sample size, the pattern of mutation in adipose tissue was not altered significantly (P = 0.40). When data from all tissues were combined, a reduction in G:C --> T:A transversions was observed (P = 0.044). These results may have implications for cancer chemoprevention and provide insight into the efficacy of vitamin E supplementation in reducing spontaneous oxidative DNA damage in vivo. More dramatic alterations of mutation frequency and pattern may be observed with higher doses of vitamin E and substitution of the racemic supplement with d-alpha-tocopherol acetate.

Clinical, pathological, and genetic features of limb-girdle muscular dystrophy type 2A with new calpain 3 gene mutations in seven patients from three Japanese families

We report on the clinical, pathological, and genetic features of 7 patients with limb-girdle muscular dystrophy type 2A (LGMD2A) from three Japanese families. The mean age of onset was 9.7+/-3.1 years (mean+/-SD), and loss of ambulance occurred at 38.5+/-2.1 years. Muscle atrophy was predominant in the pelvic and shoulder girdles, and proximal limb muscles. Muscle pathology revealed dystrophic changes. In two families, an identical G to C mutation at position 1080 the in calpain 3 gene was identified, and a frameshift mutation (1796insA) was found in the third family. The former mutation results in a W360R substitution in the proteolytic site of calpain 3, and the latter in a deletion of the Ca2+-binding domain.

New missense mutation in the alpha-sarcoglycan gene in a Japanese patient with severe childhood autosomal recessive muscular dystrophy with incomplete alpha-sarcoglycan deficiency

A new homozygous alpha-sarcoglycan (adhalin) gene mutation was found in a Japanese patient with severe childhood autosomal recessive muscular dystrophy (SCARMD). Muscle biopsy specimens from the patient showed marked reduction but not complete deficiency of alpha-sarcoglycan. The sequence of part of exon 3 of the alpha-sarcoglycan gene exhibited a cytosine to thymidine substitution at nucleotide position 220. Since the same mutation was not found in 100 normal control samples, this new alpha-sarcoglycan gene mutation is not a polymorphism but is presumed to be responsible for the marked reduction of alpha-sarcoglycan in skeletal muscle. Most patients with homozygous alpha-sarcoglycan gene mutation were reported to show complete alpha-sarcoglycan deficiency. Present case showed the homozygous missense mutation of alpha-sarcoglycan and associated with incomplete alpha-sarcoglycan deficiency and severe clinical phenotype.

Interferon alpha-2a therapy for disseminated intravascular coagulation in a patient with blue rubber bleb nevus syndrome. A case report

The authors present a sixteen-year-old girl with blue rubber bleb nevus syndrome (BRBNS) associated with disseminated hemangiomas involving the skin, oral cavity, skeletal muscle, and cerebrum. Although she denied neurologic symptoms, magnetic resonance imaging of the brain demonstrated dilatated cerebral veins and the Chiari I malformation. Examination of hemostasis revealed disseminated intravascular coagulation (DIC) manifesting as Kasabach-Merritt syndrome, with the potential for life-threatening bleeding or thrombosis in the central nervous system. Since successful management of life-threatening hemangiomas with interferon alpha-2a (IFN alpha-2a) has been reported, the authors administered IFN alpha-2a with an improvement in hemostasis. These findings suggest that IFN alpha-2a therapy is beneficial for relieving the life-threatening consumptive coagulopathy associated with BRBNS.

Preferential subsarcolemmal localization of dystrophin and beta-dystroglycan mRNA in human skeletal muscles

The intracellular localization of dystrophin and beta-dystroglycan mRNA in skeletal muscles of patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) and normal subjects was examined by in situ hybridization using biotinylated oligonucleotide probes. These mRNAs were found preferentially in sarcolemma in the skeletal muscles of both normal subjects and affected patients. Quantitative analysis of mRNA signals demonstrated no prominent reduction of dystrophin or beta-dystroglycan mRNA in DMD/BMD muscles. These results suggest that even mRNAs with deletions contain specific information that affects their localization, and the characteristic defect of dystrophin in DMD/BMD muscles seems to be caused mainly by the instability of dystrophin protein, as a post-transcriptional event.

Induction of dystrophin-associated proteins together with nicotinic acetylcholine receptors by denervation in the absence of dystrophin in skeletal muscles of mdx mice

We purified the nicotinic acetylcholine receptor from digitonin-solubilized rabbit skeletal muscle by affinity chromatography and detected many proteins linked to AChR, including dystrophin, adhalin, beta-dystroglycan, utrophin, rapsyn, and actin. To determine whether or not AChR links to dystrophin-associated proteins (DAPs) without dystrophin, we studied the effects of denervation on AChR and DAPs in the skeletal muscle of a mdx mouse. Following surgical denervation, the levels of adhalin and beta-dystroglycan dramatically increased at the extrajunctional sarcolemma with AChR, suggesting that their association is independent of dystrophin. Furthermore, the diffuse extrajunctional appearance of adhalin, beta-dystroglycan, and AChR was observed after pharmacological denervation through the subcutaneous administration of succinylcholine. Since the depletion of DAPs and the subsequent disruption of sarcolemmal linkage are believed to be a primary cause of muscle cell necrosis in dystrophinopathies, pharmacological denervation may have some beneficial effect on these diseases.

Oxidative damage to skeletal muscle DNA from patients with mitochondrial encephalomyopathies

To estimate the oxidative damage to skeletal muscle DNA in mitochondrial encephalomyopathies, we studied the amount of 8-hydroxy-deoxyguanosine (8-OH-dG) and the localization of superoxide dismutase (SOD) in the skeletal muscles of patients with progressive external ophthalmoplegia (PEO) or Kearns-Sayre syndrome (KSS). The molar ratio of 8-OH-dG/deoxyguanosine in skeletal muscle from PEO or KSS patients was significantly higher than the control value. The ratio from patients with polymyositis or Duchenne's muscular dystrophy was not significantly elevated. Immunohistochemical staining for both Mn-SOD and Cu,Zn-SOD showed pronounced staining in the subsarcolemmal and intermyofibrillar regions of cytochrome-oxidase-negative ragged red fibers of KSS or PEO muscles. Our findings suggest that overproduction of 8-OH-dG and mitochondrial dysfunction with gene deletions are associated with each other in muscle cells of patients with PEO or KSS, and that free radicals may play an important role in the pathophysiology of mitochondrial encephalomyopathies.

Localization and amount of myoglobin and myoglobin mRNA in ragged-red fiber of patients with mitochondrial encephalomyopathy

The localization and amounts of myoglobin (Mb) and Mb mRNA in ragged-red fibers (RRF) in skeletal muscle of 6 patients with mitochondrial encephalomyopathy were examined immunohistochemically and by in situ hybridization. The amounts of Mb and Mb mRNA were expressed in terms of optical densities (ODs) of Mb immunostaining and Mb mRNA signals. In nonatrophic RRF, Mb was predominantly seen in the ragged-red region and Mb mRNA signals were increased throughout the sarcoplasm. The amounts of Mb and Mb mRNA in nonatrophic RRF were greater than those in nonatrophic non-RRF. In contrast, the localization and amount in atrophic RRF were similar to those in atrophic non-RRF. Thus, Mb synthesis in nonatrophic RRF may increase to compensate for mitochondrial dysfunction and to supply sufficient oxygen to mitochondria, but this compensatory function may be impaired in atrophic RRF.

Lysosomal enzyme activities in skeletal muscle of patients with neuromuscular diseases

Activities of nine lysosomal enzymes and pH-dependent isozyme patterns of alpha-mannosidase were examined in the skeletal muscle of patients with neuromuscular diseases, and the ratios of these enzyme activities in leukocytes to those in myocytes (L/M ratio) were determined. The activities of enzymes with a high L/M ratio were markedly increased in the muscles of patients with Duchenne muscular dystrophy (DMD), myotonic dystrophy (MyD), or polymyositis (PM). In contrast, those which showed a low L/M ratio were increased in the muscles of amyotrophic lateral sclerosis (ALS) and disuse muscle atrophy (DUA). The isozyme pattern of alpha-mannosidase in DMD muscle resembled that in leukocytes, while those in ALS and DUA muscle resembled that in normal muscle. These results may suggest that the increased activity of lysosomal enzymes in the muscles of patients with DMD, MyD, or PM is due primarily to infiltrating leukocytes, while that in patients with ALS or DUA is due to intramyofiber lysosomes.

Mitochondrial encephalomyopathy with autosomal dominant inheritance: a clinical and genetic entity of mitochondrial diseases

We report a Japanese family with chronic progressive external ophthalmoplegia (CPEO) with autosomal dominant inheritance, and review 54 reported CPEO patients in seven families (including the present family) with autosomal dominant inheritance and mtDNA deletions in the skeletal muscle. Mean age at onset in the CPEO was 26 years, which is older than that in published solitary cases. In addition to blepharoptosis and external opthalmoplegia, proximal muscle atrophy and weakness were found in 62%, hearing loss in 25%, and ataxia in 17% of the patients. Retinal degeneration was not found, and cardiac involvement was very rare. mtDNA deletions in the muscle were multiple and large scale, and all such deletions were located in the non-D-loop region. Autosomal dominant CPEO has unique clinical features which differ from those of solitary CPEO, and is associated with multiple large-scale mtDNA deletions. Thus, autosomal dominant CPEO can be considered a clinical and genetic entity of mitochondrial diseases.

Graves' disease in HTLV-I carriers

Three carriers of human T-lymphotropic virus type I (HTLV-I) with Graves' disease are reported. All three cases were complicated with uveitis, and one also showed chronic arthropathy. Anti-HLTV-I antibody was found in the serum by the particle agglutination method and western blotting, and HTLV-I proviral DNA was detected in peripheral lymphocytes by the polymerase chain reaction and Southern blotting. HTLV-I is a causal agent of adult T-cell leukemia and HTLV-I associated myelopathy/tropical spastic paraparesis, and is believed to be related to the pathogenesis of diseases such as chronic arthropathy, uveitis, chronic bronchoalveolitis, and Sjögren's syndrome. On the other hand, retrovirus infection is considered to cause autoimmune diseases. Thus, the pathogenesis of Graves' disease in the present patients might be associated with HTLV-I infection.

[A case of Kearns-Sayre syndrome whose asymptomatic mother had abnormal mitochondria in skeletal muscle]

The mode of inheritance of Kearns-Sayre syndrome (KSS) and chronic progressive external ophthalmoplegia (CPEO) have not yet been established, since most cases are sporadic. We studied skeletal muscle pathology and mitochondrial DNA (mtDNA) in a sporadic KSS patient (proband) and examined mitochondrial function of the muscle in his asymptomatic family members. The proband was a 56-year-old male with bilateral ptosis, external ophthalmoplegia, retinal degeneration and cardiac conduction disturbance. Biopsied deltoid muscle showed 9.7% of ragged red fibers without cytochrome oxidase (COX) activity and abnormal mitochondria on electron microscopy. Analysis of muscle mtDNA revealed a 4,977 bp deletion between nt. 8,483 and 13,459. None of the family members had symptoms similar to those of the proband. However, an aerobic exercise test of 15W for 15 minutes with an ergometer induced a marked increase in serum lactate levels in the proband's mother. Histology of her biopsied deltoid muscle showed 0.3% of ragged red fibers without COX activity and morphologically abnormal mitochondria. These findings indicate that the abnormal mitochondria of the proband were transmitted from his asymptomatic mother. This also suggests that some of the sporadic KSS/CPEO cases are inherited one.

Syndrome of inappropriate secretion of ADH (SIADH) due to small cell lung cancer with extremely high plasma vasopressin level

A 76-year-old man with small cell lung cancer associated with the syndrome of inappropriate secretion of ADH (SIADH) visited our hospital. The serum Na level was normal on the first visit, but 2 weeks later it decreased to 114 mEq/L with an extremely high plasma vasopressin (VP) level of 1520 pg/ml. Serum Na was normalized after the reduction of the tumor size by chemotherapy, but the plasma VP level remained between 150 to 600 pg/ml. On gel filtration of plasma VP two peaks of immunoreactive VP were eluted at the positions of a larger molecule than authentic VP and authentic VP, and VP in urine gave only one peak compared to that of authentic VP. The dilution curve of plasma VP was almost parallel and that of urine was completely parallel to the standard curve. These findings suggest that a larger VP with low physiological activity was predominantly secreted in the present patient and manifested relatively mild symptoms despite the extremely high plasma VP level.