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Introduction/aims: Small fiber neuropathies (SFN) have been associated with two autoantibodies, trisulfated heparin disaccharide (TS-HDS) and fibroblast growth factor receptor 3 (FGFR-3), and intravenous immune globulin (IVIG) has been suggested as a potential therapy. The study objective is to determine the efficacy of IVIG on nerve density, pain and neurologic examinations in patients with SFN associated with TS-HDS and FGFR-3 autoantibodies.Methods: This was a double-blind placebo-controlled pilot study. Subjects with SFN confirmed by history, examination, and skin biopsy with elevated autoantibodies to TS-HDS and/or FGFR-3 received IVIG (or blinded placebo) 2 grams/kg followed by 1 gram/kg every 3 wk for a total of 6 treatments. All subjects had Utah Early Neuropathy Scores (UENS), questionnaires and skin biopsies with quantitation of intra-epidermal nerve fiber density (IENFD) taken from adjacent sites at the distal leg at baseline and 6 mo later. The primary outcome was the change in IENFD over 6 mo.Results: Twenty subjects were enrolled; 17 completed treatment (8 IVIG, 9 placebo). Three did not have final data due to coronavirus disease 2019 (COVID-19). Skin biopsy IENFD improved by 0.5 ± 0.8 fibers/mm in the placebo group and improved by 0.6 ± 0.6 fibers/mm in the IVIG-treated group (p = NS).Over 24 wk the change in pain scores (11 point pain scale) was -1.9 ± 2.6 in the placebo group, and - 1.7 ± 0.9 in the IVIG group (p = NS), the UENS improved by 3.0 ± 5.8 in the placebo group and improved by 1.8 ± 3.9 in the IVIG group (p = NS).Discussion: This pilot study did not detect a benefit of treatment with IVIG in patients with SFN and autoantibodies to TS-HDS and FGFR-3. [ABSTRACT FROM AUTHOR]

Background: Anti-cytosolic 5'-nucleotidase 1A (cN1A) antibodies are commonly detected in patients with sporadic inclusion body myositis (sIBM). However, their pathogenic role has not been established. Moreover, efforts toward identifying sIBM distinct clinicopathologic characteristics associated with these antibodies have yielded conflicting results.Methods: We first searched for patients, seen in our clinics, tested for anti-cN1A antibodies between December 2015 and December 2019. We identified 92 patients who were diagnosed with sIBM, according to the 2011 ENMC or Griggs et al criteria. Thereafter, we reviewed and compared the clinical and investigational findings of these patients in relation to their antibody status.Results: Anti-cN1A antibodies were present in 47/92 (51%) patients with sIBM. Comparison of seropositive and seronegative cohorts yielded no significant difference in clinical features, including facial weakness, oropharyngeal and respiratory involvement, or disease severity. The antibody titer did not correlate with the clinical phenotype, CK value, or presence of myotonic discharges on EMG. Anti-cN1A antibody positive patients appeared to have more frequent auto-aggressive inflammation on muscle biopsy but not as an isolated myopathological feature.Conclusions: Our study showed that anti-cN1A antibody positive and negative sIBM patients have similar clinical features and disease severity. Anti-cN1A antibodies in our sIBM cohort did not correlate with any studied clinical or laboratory parameter and, therefore, were of limited value in the patient's assessment. [ABSTRACT FROM AUTHOR]

Introduction: In this study we aimed to clarify the association between interleukin-6 (IL-6) secretion in fibroblasts in carpal tunnel syndrome (CTS) patients and their biophysical parameters, including association with trigger finger and whether tranilast inhibits IL-6 secretion in fibroblasts.Methods: Fibroblasts were obtained from tenosynovial tissue harvested from idiopathic CTS patients undergoing carpal tunnel release and tenosynovectomy and cultured in media containing tranilast with or without tumor necrosis-α (TNF-α) or interleukin-1β (IL-1β). Their proliferation was evaluated and secreted IL-6 levels and IL-6 mRNA expression were quantified. Correlations between IL-6 concentration and patient characteristics were examined.Results: IL-6 secretion was significantly associated with trigger finger (P = .001). Tranilast inhibited fibroblast proliferation in a dose-dependent manner and suppressed IL-6 secretion.Discussion: IL-6 overproduction in tenosynovial tissue may account for the association between CTS and trigger finger. Future studies should investigate whether tranilast can be used to treat patients with CTS. [ABSTRACT FROM AUTHOR]

Introduction: HMG-CoA reductase inhibitors (statins) and H63D HFE polymorphism may modify amyotrophic lateral sclerosis (ALS). We hypothesized that statins worsen phenotype in ALS mice, dependent on HFE genotype.Methods: Mice harboring SOD1(G93A) heterozygous for H67D Hfe (homologous to human H63D HFE) were administered simvastatin and/or coenzyme Q10, and were allowed to reach end stage. Disease progression was measured by grip strength. A separate group of animals was administered simvastatin and euthanized at the symptomatic 120-day time-point. Mitochondria from gastrocnemius muscle and lumbar spine were analyzed.Results: Simvastatin and H67D Hfe accelerated disease progression. Simvastatin decreased survival. Coenzyme Q10 did not rescue statin-induced effects. Statins did not alter mitochondrial protein levels.Conclusions: Statins and Hfe genotype alter disease course in the ALS mouse model. Because the H63D HFE polymorphism is present in 30% of patients with ALS, studying disease progression in patients who receive statins, stratified for HFE genotype, may guide therapy. Muscle Nerve, 2016 Muscle Nerve 54: 284-291, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT The paraproteinemias are a heterogeneous group of disorders in which monoclonal plasma cells cause the proliferation of monoclonal proteins. They are of importance to clinicians because they often occur in association with neuropathies. Neurologists play a particularly important role when the neuropathy is the presenting feature, in which case they may uncover clinical, laboratory, radiologic, electrodiagnostic, or biopsy findings that lead to identification of the underlying paraproteinemia. The frequency of neuropathies in these patients, and the extent to which such neuropathies dominate the clinical picture, varies significantly between the different paraproteinemias. Treatments may be aimed specifically at the neuropathy, or against the underlying hematologic disorder. In all patients with paraproteinemias, the neurologist can work collaboratively with the hematologist to formulate therapeutic plans and goals and can provide follow-up and monitoring to determine the response of the neuropathy to treatment. Muscle Nerve 51: 1-13, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT Statins are among the most commonly prescribed medications that significantly reduce cardiovascular risk in selected individuals. However, these drugs can also be associated with muscle symptoms ranging from mild myalgias to severe rhabdomyolysis. Although statin myotoxicity is usually self-limited, in some instances statin-exposed subjects can develop an autoimmune myopathy typically characterized by progressive weakness, muscle enzyme elevations, a necrotizing myopathy on muscle biopsy, and autoantibodies that recognize 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the pharmacologic target of statins. These antibodies are also found in some autoimmune myopathy patients without statin exposure. Importantly, anti-HMGCR antibodies are not found in the vast majority of statin-exposed subjects without autoimmune myopathy, including those with self-limited statin intolerance. Thus, testing for these antibodies may help differentiate those with self-limited statin myopathy who recover after statin discontinuation from those with a progressive statin-associated autoimmune myopathy who typically require immunosuppressive therapy. Muscle Nerve 48: 477-483, 2013 [ABSTRACT FROM AUTHOR]

Introduction: Viperid snakebite envenomings are characterized by muscle necrosis and a deficient regenerative response. Methods: Homogenates from gastrocnemius muscles of mice injected with the venom of the snake Bothrops asper or with 2 tissue-damaging toxins were added to cultures of C2C12 myogenic cells. Myoblasts proliferation and fusion were assessed. Venom was detected by immunoassay in mouse muscle during the first week after injection. Results: Homogenates from venom-injected muscle induced a drop in the number of proliferating myoblasts and a complete elimination of myotube formation. The inhibitory effect induced by homogenates from venom-injected mice was abrogated by preincubation of the homogenate with antivenom antibodies but not with control antibodies. This finding provides evidence that the effect is due to the action of venom in the tissue. Conclusions: Our observations suggest that traces of venom in muscle tissue might inhibit myotube formation and preclude a successful regenerative response. Muscle Nerve, 2013 [ABSTRACT FROM AUTHOR]

Introduction: We previously reported that protein biomarkers of neuronal death and glial pathology were elevated in the cerebrospinal fluid of patients with West Nile virus (WNV) infection, including WNV fever. Therefore, we hypothesized that the glial biomarker S100B would also be elevated in serum across the spectrum of WNV disease. Methods: Serum levels of S100B were measured by enzyme-linked immunoassay (ELISA) in 90 WNV patients (35 with neuroinvasive disease and 55 with WNV fever) and compared with 34 healthy controls. Results: Serum S100B was significantly higher in patients (median 0.17 ng/ml) than in controls (0.09 ng/ml, P < 0.0001). Serum S100B was elevated in 16 cases (46%) with neuroinvasive disease and in 19 cases (35%) with WNV fever. Conclusions: The increase in serum S100B reaffirms pathological changes across the spectrum of WNV disease. The elevated S100B in over one third of WNV fever cases implies that neuroinvasion occurs in a much greater proportion of patients than anticipated by clinical and epidemiological data. Muscle Nerve 45: 826-830, 2012 [ABSTRACT FROM AUTHOR]

Introduction: In this investigation we studied clinical and laboratory features of polyneuropathies in patients with serum IgM binding to the trisulfated disaccharide IdoA2S-GlcNS-6S (TS-HDS). Methods: We retrospectively compared 58 patients with selective IgM binding to TS-HDS to 41 consecutive patients with polyneuropathies without TS-HDS binding. Results: Patients with IgM vs. TS-HDS commonly had distal, sensory, axonal neuropathies. Weakness was associated with IgM M-proteins. Hand pain and serum IgM M-proteins were more common than in control neuropathy patients. TS-HDS antibody binding was often selectively κ class. Biopsies showed capillary pathology with thickened basal lamina and C5b9 complement deposition. IgM in sera with TS-HDS antibodies often bound to capillaries. Conclusions: Serum IgM binding to TS-HDS is associated with painful, sensory > motor, polyneuropathies with an increased frequency of persistent hand discomfort, serum IgM M-proteins, and capillary pathology. Serum IgM binding to TS-HDS suggests a possible immune etiology underlying some otherwise idiopathic sensory polyneuropathies. Muscle Nerve 45: 866-872, 2012 [ABSTRACT FROM AUTHOR]

Introduction: HLA-DQ8 transgenic mice develop ocular myasthenia gravis (oMG), which then progresses to generalized MG (gMG) when immunized with the human acetylcholine receptor (H-AChR) α subunit. Because the fetal AChR γ subunit is expressed in adult extraocular muscles, we anticipated that γ subunit immunization would generate an immune response to mouse AChR and induce MG in mice. Results: H-AChR γ subunit immunization in HLA-DQ8 mice induced an autoimmune response to mouse AChR and led to the destruction of AChR in the neuromuscular junction (NMJ) by anti-AChR antibody and complement activation, and it triggered upregulation of AChR gene transcription. Conclusion: Our findings indicate that oMG may be induced by immunity to the AChR γ subunit. Muscle Nerve, 2012 [ABSTRACT FROM AUTHOR]

Overproduction of reactive oxygen species (ROS) can damage cellular macromolecules and lead to cellular dysfunction or death. Exercise training induces beneficial adaptations in skeletal muscle that may reduce cellular damage from exposure to ROS. To determine the response of exercise-conditioned muscle to acute increases in ROS, four groups of mice were used: non-trained (NT, n = 12); NT + high-dose radiation (HDR, n = 3); exercise-trained (EX, n = 13, 3 days/week for 10 weeks, 10 m/min to 18 m/min); and EX + HDR ( n = 3/group). Quadriceps muscle was harvested 3-5 days following the last exercise bout in the training program for measurement of antioxidant enzyme and metabolic enzyme activity. Total superoxide dismutase (41%), and manganese sodium oxide dismutase (51%) activities were significantly increased in radiation-challenged EX mice as compared with unchallenged EX mice (all P ≤ 0.05). No such increase was observed in NT mice. Citrate synthase (42%) and cytochrome c oxidase (38%) activities were both elevated in radiation-challenged EX mice as compared with unchallenged EX mice (both P < 0.05), and no such increase was observed in NT. We demonstrate that preconditioning skeletal muscle with EX enhances the response of antioxidant and mitochondrial enzymes to radiation. Muscle Nerve, 2011 [ABSTRACT FROM AUTHOR]

Denervation of skeletal muscles results in loss of muscle mass and contractile force. Recent evidence suggests that local immune system activation plays a key role in these processes, but the mechanisms underlying muscle-immune system cross-talk are not understood. The purpose of this study was to address the mechanisms by which muscle responds to denervation and to elucidate the specific role played by FYN in local immune system activation. We studied initial events taking place in the gastrocnemius of wild-type and Fyn−/− mice following sciatic nerve transection. Discontinuous sucrose gradient centrifugation was used to prepare lipid rafts at different time-points (1, 7, and 14 days) after surgery. Activation of FYN, cytokine expression (IL-1β and TNF-α), and T-cell activation (CD3 and IL-15) were followed by in vitro kinase assays, enzyme-linked immunoassay (ELISA), Western blotting, and immunoprecipitation. Sciatic nerve injury resulted in increased SRC kinase activity in gastrocnemius lipid rafts. Production of both IL-1β and TNF-α was increased, peaking after 1 day, followed after 7 and 14 days by upregulation of IL-15 and CD3 expression and the development of caveolin-3 and CD3 complexes. The integrity of lipid rafts and the upregulation of SRC kinase activity, cytokine expression, and T-cell activation and cross-talk with muscle cells following denervation were abolished in Fyn−/− mice. The integrity of FYN-dependent lipid rafts is required for local immune system activation within denervated muscle, and lipid rafts are implicated in orchestrating muscle-immune-cell cross-talk. These results are likely to provide new insights into the therapy of neuromuscular injury. Muscle Nerve, 2010 [ABSTRACT FROM AUTHOR]

The stromal cell-derived factor (SDF)-1/CXC receptor 4 (CXCR4) axis has been shown to play a role in skeletal muscle development, but its contribution to postnatal myogenesis and the role of the alternate SDF-1 receptor, CXC receptor 7 (CXCR7), are poorly characterized. Western blot analysis and real-time polymerase chain reaction (PCR) were performed to evaluate in vitro the effect of SDF-1 and CXCR4 and CXCR7 inhibition on myogenic differentiation. Proliferating myoblasts express CXCR4, CXCR7, and SDF-1; during myogenic differentiation, CXCR4 and CXCR7 levels are downregulated, and SDF-1 release is decreased. SDF-1 anticipates myosin heavy chain accumulation and myotube formation in both C2C12 myoblasts and satellite cells. Interestingly, inhibition of CXCR4 and CXCR7 signaling, either by drugs or RNA interfererence, blocks myogenic differentiation. Further, the CXCR4 antagonist, 4F-benzoyl-TN14003, inhibits myoblast cell cycle withdrawal and decreases the retinoblastoma gene (pRb) product accumulation in its hypophosphorylated form. Our experiments demonstrate that SDF-1 regulates myogenic differentiation via both CXCR4 and CXCR7 chemokine receptors. Muscle Nerve 000:000-000, 2010 [ABSTRACT FROM AUTHOR]

Both multifocal, demyelinating features and prednisone responsiveness are rare in Charcot-Marie-Tooth (CMT) disease. We report a mother and son with a prednisone-responsive, multifocal, demyelinating, predominantly sensory polyneuropathy that was associated with an isoleucine92valine polymorphism of lipopolysaccharide-induced TNF-alpha factor (LITAF). The mother had a multifocal, acquired, demyelinating sensory and motor polyneuropathy (MADSAM)-like presentation. The son developed left peroneal neuropathy during acute Lyme disease with a subsequent relapsing, MADSAM-like illness, despite antibiotic treatment. Both shared prednisone responsiveness and multifocal, demyelinating features electrophysiologically. MADSAM may be familial (FaDSAM) and respond to prednisone. Muscle Nerve 41: 558-562, 2010 [ABSTRACT FROM AUTHOR]

We describe a patient with both neurofibromatosis type 1 and Charcot-Marie-Tooth disease type 1B. Although one might expect an overwhelming tumor burden due to the combination of these two disorders, the two mutations did not appear to interact. Muscle Nerve 41: 555-558, 2010 [ABSTRACT FROM AUTHOR]

Introduction: A 56-year-old man with a distant history of statin use presented with progressive isolated very proximal lower limb and truncal weakness. Electromyogram (EMG) showed isolated gluteal and lumbar paraspinal muscle involvement. Methods: Gluteus medius muscle biopsy was performed under general anesthesia. Results: The biopsy showed a pauci-inflammatory necrotizing myopathy. Serum antibodies to 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) were positive. He has since partially responded to corticosteroids and methotrexate. Conclusions: Anti-HMGCR-associated necrotizing autoimmune myopathy (NAM) can present in a restricted form after cessation of a statin. Biopsy of a symptomatic but uncommonly studied muscle is worthwhile. Muscle Nerve 54: 150-152, 2016 [ABSTRACT FROM AUTHOR]

Previous studies have shown increased expression of acetylcholine receptor-alpha (AChR-α) subunit transcripts in myasthenia gravis (MG) and experimental MG (EAMG), but none examined the functional properties of this overexpression. In this study we examined the mRNA and protein expression of AChR-α as well as the pattern of α-bungarotoxin labeling in muscle tissue from EAMG mice with varying disease severity. AChR-α expression was increased considerably in endplates from mice with severe EAMG, but it was distinct and greatly in excess of α-bungarotoxin labeling. This 'aberrant expression' occurred in mice with morphologic endplate damage, and the pattern of complement and immunoglobulin deposition in muscle from these mice appeared to mirror the pattern of AChR-α expression. The loss of functional AChR in severe MG increases transcription of AChR-α mRNA, but the expressed protein is 'functionally inert,' failing to compensate for loss of AChR. This enhanced expression of AChR may play a role in driving the ongoing autoimmune response. Muscle Nerve 40: 279-286, 2009 [ABSTRACT FROM AUTHOR]

Platelet-derived microparticle (PDMP) levels were measured using an enzyme-linked immunosorbent assay (ELISA) to elucidate the role of platelet activation in patients with polymyositis or dermatomyositis (PM/DM). PDMP levels in active PM/DM patients (median 13.3 U/ml, interquartile range 9.9-20.7 U/ml, n = 16) and those in patients undergoing treatment (12.1 U/ml, 7.4-16.7 U/ml, n = 12) were significantly higher than in controls (6.5 U/ml, 5.0-8.4 U/ml, n = 26, vs. active, P = 0.0001; vs. treatment, P = 0.004). In a paired sampling study, PDMP decreased significantly after glucocorticoid treatment ( P = 0.04). PDMP in the active PM/DM patients correlated significantly with serum C-reactive protein levels ( rs = 0.67, P = 0.01). These results suggest that platelets may play an important role in the inflammatory process, and that PDMP level could be a useful marker of inflammatory activity in PM/DM patients. Muscle Nerve 39: 586-590, 2009 [ABSTRACT FROM AUTHOR]

Celiac disease is usually associated with autoimmune disorders and has occasionally been reported in patients with inflammatory myopathies. Our aim was to determine the presence of celiac disease and antibodies associated with celiac disease in patients with inflammatory myopathies and to investigate their relationship. Serum antigliadin, anti-tissue transglutaminase, and antiendomysial antibodies were determined in 51 patients with inflammatory myopathies. HLA-DQ2 and -DQ8 alleles were studied to assess their complementary diagnostic value. Jejunal biopsy was performed in patients with moderate to high levels of antigliadin antibodies. Patients with jejunal histology consistent with celiac disease initiated a gluten-free diet. Seventeen patients (31%) were positive for antigliadin antibodies, which were significantly more frequent in patients with inclusion-body myositis than dermatomyositis ( P < 0.001). Positive status to HLA-DQ2 and/or -DQ8 did not differ between antigliadin-positive (75% and 12.5%) or -negative (60% and 15%) patients. Three of five jejunal biopsies were diagnostic for celiac disease with histological normalization after a gluten-free diet. Thus, celiac disease is more prevalent in patients with inflammatory myopathies than in the general population. Positive status to HLA-DQ2 allele, which is known to be more frequent in patients with inflammatory myopathies, could explain the high prevalence of antigliadin antibodies in this population. The diagnostic value of HLA-DQ2 or -DQ8 haplotypes to detect celiac disease in patients with inflammatory myopathy is limited. Muscle Nerve, 2006 [ABSTRACT FROM AUTHOR]

Lyme disease is sometimes part of the differential diagnosis for amyotrophic lateral sclerosis (ALS). Herein we report on 414 individuals with ALS at the Massachusetts General Hospital who underwent laboratory testing for Lyme disease. Twenty-four (5.8%) were seropositive, but only 4 (0.97%) had confirmed past immunoreactive infection. Two of these patients received ceftriaxone for 1 month without clinical improvement. Lyme disease was rare in 414 patients with ALS and is not likely to be causative. Muscle Nerve, 2009 [ABSTRACT FROM AUTHOR]

ABSTRACT Introduction: The aim of this study was to examine the relationship between serum C-terminal agrin fragment (CAF) concentrations and neuromuscular fatigue in older adults. Methods: Twenty-two healthy older men and women volunteered for this study. Resting fasted blood samples were collected and prepared for measurement of serum CAF concentration by a commercially available ELISA kit. The onset of neuromuscular fatigue was measured by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at fatigue threshold (PWCFT) test. Results: A significant inverse correlation for men was observed between CAF and PWCFT ( r = −0.602; P = 0.05), but not for women ( r = 0.208; P = 0.54). After controlling for age and body mass index, significant correlations ( r = −0.69; P = 0.042) remained for men, but not for women ( r = 0.12; P = 0.76). Conclusions: These data suggest that serum CAF concentrations were significantly related to the onset of neuromuscular fatigue independent of age and BMI in men only. Muscle Nerve 51: 132-133, 2015 [ABSTRACT FROM AUTHOR]