Significant Muscle Weakness Research Articles

Platelet-rich plasma ameliorates dexamethasone-induced myopathy by suppressing autophagy and enhancing myogenic potential through modulation of Myo-D, Pax-7, and myogenin expression

BackgroundMuscle tissue is essential for overall well-being that declines with age and different illnesses. Glucocorticoids, despite being efficient in treating inflammation, can induce muscle weakness (known as glucocorticoid-induced myopathy) by affecting protein breakdown and synthesis. Glucocorticoids have a negative impact on satellite cells, which play a role in muscle regeneration. Platelet rich plasma (PRP), containing concentrated growth factors, has a potential role in enhancing tissue repair and could be used to ameliorates combat muscle wasting caused by glucocorticoids. AimThe purpose of this study was to identify how PRP can affect dexamethasone-induced myopathy in a rat model. MethodsTwenty-four male rats were divided into four equal groups: control, PRP, steroid (dexamethasone) treated for induction of myopathy, and steroid then treated with PRP for three weeks. Skeletal muscle contractile properties, protein content of the muscle, oxidative stress markers, histological structure, myogenin gene expression and immunohistochemical expression of Myo-D, Pax-7 and LC3 were assessed. Resultsdexamethasone caused significant muscle weakness, decreased protein content, increased oxidative stress, decreased expression of myogenic genes and upregulated LC3 expression. PRP administration significantly improved muscle function, increased protein content, reduced oxidative stress, and upregulated myogenic genes. Histological results confirmed these findings. Additionally, PRP decreased autophagy marker LC3 expression and increased muscle stem cell markers MyoD and Pax7. ConclusionThese results suggested that PRP could effectively prevent and reverse dexamethasone-induced muscle atrophy by promoting muscle protein synthesis, reducing oxidative stress, decreasing autophagy, and enhancing muscle stem cell activity. This study supports the potential role of PRP as a therapeutic strategy for muscle wasting disorders.

Genotype‒phenotype correlation in recessive DNAJB4 myopathy.

Protein aggregate myopathies can result from pathogenic variants in genes encoding protein chaperones. DNAJB4 is a cochaperone belonging to the heat shock protein-40 (HSP40) family and plays a vital role in cellular proteostasis. Recessive loss-of-function variants in DNAJB4 cause myopathy with early respiratory failure and spinal rigidity, presenting from infancy to adulthood. This study investigated the broader clinical and genetic spectrum of DNAJB4 myopathy. In this study, we performed whole-exome sequencing on seven patients with early respiratory failure of unknown genetic etiology. We identified five distinct pathogenic variants in DNAJB4 in five unrelated families of diverse ethnic backgrounds: three loss-of-function variants (c.547C > T, p.R183*; c.775C > T, p.R259*; an exon 2 deletion) and two missense variants (c.105G > C, p.K35N; c.181A > G, p.R61G). All patients were homozygous. Most affected individuals exhibited early respiratory failure, and patients from three families had rigid spine syndrome with axial weakness in proportion to appendicular weakness. Additional symptoms included dysphagia, ankle contractures, scoliosis, neck stiffness, and cardiac dysfunction. Notably, J-domain missense variants were associated with a more severe phenotype, including an earlier age of onset and a higher mortality rate, suggesting a strong genotype‒phenotype correlation. Consistent with a loss of function, the nonsense variants presented decreased stability. In contrast, the missense variants exhibited normal or increased stability but behaved as loss-of-function variants in yeast complementation and TDP-43 disaggregation assays. Our findings suggest that DNAJB4 is an emerging cause of myopathy with rigid spine syndrome of variable age of onset and severity. This diagnosis should be considered in individuals presenting with suggestive symptoms, particularly if they exhibit neck stiffness during infancy or experience respiratory failure in adults without significant limb muscle weakness. Missense variants in the J domain may predict a more severe phenotype.

An Orai1 gain-of-function tubular aggregate myopathy mouse model phenocopies key features of the human disease.

Tubular aggregate myopathy (TAM) is a heritable myopathy primarily characterized by progressive muscle weakness, elevated levels of creatine kinase (CK), hypocalcemia, exercise intolerance, and the presence of tubular aggregates (TAs). Here, we generated a knock-in mouse model based on a human gain-of-function mutation which results in a severe, early-onset form of TAM, by inducing a glycine-to-serine point mutation in the ORAI1 pore (Orai1G100S/+ or GS mice). By 8 months of age, GS mice exhibited significant muscle weakness, exercise intolerance, elevated CK levels, hypocalcemia, and robust TA presence. Unexpectedly, constitutive Ca2+ entry in mutant mice was observed in muscle only during early development and was abolished in adult skeletal muscle, partly due to reduced ORAI1 expression. Consistent with proteomic results, significant mitochondrial damage and dysfunction was observed in skeletal muscle of GS mice. Thus, GS mice represent a powerful model for investigation of the pathophysiological mechanisms that underlie key TAM symptoms, as well as those compensatory responses that limit the damaging effects of uncontrolled ORAI1-mediated Ca2+ influx.

Genotype-phenotype correlation in recessive DNAJB4 myopathy.

Protein aggregate myopathies can result from pathogenic variants in genes encoding protein chaperones. DNAJB4 is a cochaperone belonging to the heat shock protein-40 (HSP40) family and plays a vital role in cellular proteostasis. Recessive loss-of-function variants in DNAJB4 cause myopathy with early respiratory failure and spinal rigidity, presenting from infancy to adulthood. This study investigated the broader clinical and genetic spectrum of DNAJB4 myopathy. In this study, we performed whole-exome sequencing on seven patients with early respiratory failure of unknown genetic etiology. We identified five distinct pathogenic variants in DNAJB4 in five unrelated families of diverse ethnic backgrounds: three loss-of-function variants (c.547C > T, p.R183*; c.775C > T, p.R259*; an exon 2 deletion) and two missense variants (c.105G > C, p.K35N; c.181A > G, p.R61G). All patients were homozygous. All affected individuals exhibited early respiratory failure, and patients from three families had rigid spine syndrome with axial weakness in proportion to appendicular weakness. Additional symptoms included dysphagia, ankle contractures, scoliosis, neck stiffness, and cardiac dysfunction. Notably, J-domain missense variants were associated with a more severe phenotype, including an earlier age of onset and a higher mortality rate, suggesting a strong genotype-phenotype correlation. Consistent with a loss of function, the nonsense variants presented decreased stability. In contrast, the missense variants exhibited normal or increased stability but behaved as loss-of-function variants in yeast complementation and TDP-43 disaggregation assays. Our findings suggest that DNAJB4 is an emerging cause of myopathy with rigid spine syndrome of variable age of onset and severity. This diagnosis should be considered in individuals presenting with suggestive symptoms, particularly if they exhibit neck stiffness during infancy or experience respiratory failure in adults without significant limb muscle weakness. Missense variants in the J-domain may predict a more severe phenotype.

Patients with anti-small ubiquitin-like modifier activating enzyme-positive dermatomyositis resembling antisynthetase syndrome with poor prognosis: a bicentric international retrospective study and literature review.

This study aimed to describe adult Brazilian and Japanese patients with anti-small ubiquitin-like modifier activating enzyme (SEA)-positive dermatomyositis (DM), as there are few studies in the literature. A literature review was also conducted. This bicentric international retrospective study, conducted between 2012 and 2023, included patients with anti-SAE-positive DM (2017 European League Against Rheumatism/American College of Rheumatology classification criteria). All demographic features and clinical, laboratory, therapeutic, and follow-up data were collected from Brazilian and Japanese centers using pre-standardized and parameterized information. We included 17 adult patients with a median age of 65 (56-76) and a predominance of females (82.4%). Constitutional symptoms at baseline were present in 58.8% of the patients. In addition to classical cutaneous DM lesions, one-third of the patients had myalgia and significant muscle weakness, whereas half presented with dysphagia, interstitial lung disease, and joint manifestations. The first-line treatment consisted of intravenous methylprednisolone and immunoglobulin pulse therapy in 41.2% and 28.6% of the patients, respectively. The median follow-up duration was 20 (13-74) months; at the last medical evaluation, half had active disease and were still using oral glucocorticoids (median dosage, 10.0 mg/day). Approximately one-fifth to one-third of the patients were diagnosed with different types of cancer, had severe infections, or died. Patients with anti-SAE-positive DM not only resemble the phenotype of antisynthetase syndrome but are also associated with a poor prognosis.

Consensus Recommendations for Neurogenic Thoracic Outlet Syndrome from the INTOS Workgroup.

There is significant variation in methods used for diagnosis and treatment of neurogenic thoracic outlet syndrome (NTOS). The lack of definitions and criteria for diagnosis as well as controversy in treatment options hampers standardized reporting of outcomes. In the orthopedic and plastic hand surgery literature, there are not standardized guidelines to direct evidence-based practice for hand surgeons relating to NTOS. Hence, expert consensus may provide guidance for clinical practice. An international workgroup of 21 expert hand surgeons with cumulative experience of 5519 NTOS procedures was assembled. The Delphi method was used to arrive at consensus recommendations to guide diagnosis, treatment, surgery, and postoperative management of patients with NTOS. The workgroup achieved majority (greater than 75%) consensus with 17 statements. A modified version of the Society for Vascular Surgery clinical diagnostic criteria is recommended for diagnosis of NTOS. The elevated arm stress test and Tinel sign are recommended as provocative maneuvers. A cervical spine or chest radiograph should be routinely obtained preoperatively. Conservative management should be first line for NTOS, except in patients with significant muscle atrophy or weakness. An anterior supraclavicular approach is recommended for exposure of the supraclavicular brachial plexus, with the necessity for an additional infraclavicular approach or adjunctive surgeries indicated for specific patients. Standardized consensus guidelines help guide management of NTOS by specialized hand surgeons, with an aim toward standardizing criteria for diagnosis and treatment of patients as well as measures and tools used for research and reporting of outcomes.

Spaceflight increases sarcoplasmic reticulum Ca2+ leak and this cannot be counteracted with BuOE treatment

Spending time in a microgravity environment is known to cause significant skeletal muscle atrophy and weakness via muscle unloading, which can be partly attributed to Ca2+ dysregulation. The sarco(endo)plasmic reticulum Ca2+ ATPase (SERCA) pump is responsible for bringing Ca2+ from the cytosol into its storage site, the sarcoplasmic reticulum (SR), at the expense of ATP. We have recently demonstrated that, in the soleus of space-flown mice, the Ca2+ uptake ability of the SERCA pump is severely impaired and this may be attributed to increases in reactive oxygen/nitrogen species (RONS), to which SERCA is highly susceptible. The purpose of this study was therefore to investigate whether treatment with the antioxidant, Manganese(III) meso-tetrakis(N-n-butoxyethylpyridinium-2-yl)porphyrin, MnTnBuOE-2-PyP5+ (BuOE), could attenuate muscle atrophy and SERCA dysfunction. We received soleus muscles from the rodent research 18 mission which had male mice housed on the international space station for 35 days and treated with either saline or BuOE. Spaceflight significantly reduced the soleus:body mass ratio and significantly increased SERCA’s ionophore ratio, a measure of SR Ca2+ leak, and 4-HNE content (marker of RONS), none of which could be rescued by BuOE treatment. In conclusion, we find that spaceflight induces significant soleus muscle atrophy and SR Ca2+ leak that cannot be counteracted with BuOE treatment. Future work should investigate alternative therapeutics that are specifically aimed at increasing SERCA activation or reducing Ca2+ leak.

Exercise Rehabilitation Preserves Cardiorespiratory Muscle Function Following Doxorubicin Treatment

Doxorubicin (DOX) is a highly effective chemotherapeutic agent. Unfortunately, cancer patients who have completed DOX treatment often experience exercise intolerance, reduced cardiac function, dyspnea and unfavorable changes to body composition, ultimately, leading to increased incidence of heart failure. Exercise has been shown to reduce the risk of developing chemotherapy-induced cardiorespiratory dysfunction; however, the ability of cancer patients to exercise during treatment can be limited by cancer type, stage and fatigue. Therefore, these experiments utilized a chronic DOX-induced cardiotoxicity model to determine the effects of rehabilitative exercise on cardiorespiratory muscle function. Female Sprague-Dawley rats were treated with DOX once every three weeks for four total cycles via intravenous infusion (i.e., cumulative dose of ~160mg/m2). One-week following the completion of DOX treatment, rats remained sedentary (Sed-DOX) or were prescribed 10-weeks of moderate intensity treadmill running at 30m/min, 0% grade, 1-hour/day, and 3x/week (Mod-DOX). Body composition, exercise tolerance and echocardiography were assessed at three timepoints: 1) pre-treatment; 2) post-treatment and; 3) post-rehabilitation. Diaphragm muscle specific force production was measured post-rehabilitation. From pre- to post-treatment each group gained weight and no differences existed between groups. However, from post-treatment to post-rehabilitation body weight of the DOX-treated groups did not change and was significantly reduced compared to sedentary saline-treated (Sed-Sal) rats from week 15 onwards. Although mean body weight did not differ between the DOX-treated groups, lean mass increased in Mod-DOX rats between each timepoint with no change in fat mass, while fat mass increased in Sed-DOX rats and an initial increase in lean mass was attenuated from post-treatment to post-rehabilitation. Exercise time to fatigue did not change between timepoints within each group; however, exercise run time from post-treatment to post-rehabilitation was significantly longer in Mod-DOX rats compared to Sed-DOX and Sed-Sal. Cardiac fractional shortening percentage (FS%) was reduced in Sed-DOX rats at post-treatment and post-rehabilitation compared to pre-treatment. Additionally, posterior wall shortening velocity (PWSV) was reduced in Sed-DOX rats at post-treatment compared to pre-treatment. No differences in FS% or PWSV were seen between any timepoint in the Mod-DOX group. Finally, ex vivo diaphragm muscle function showed significant diaphragm muscle weakness in Sed-DOX rats at 15-60Hz stimulations compared to Sed-Sal. Diaphragm force production did not differ in Mod-DOX rats compared to Sed-Sal at any stimulation frequency. These results demonstrate a beneficial effect of moderate intensity rehabilitation exercise for the maintenance of body composition, cardiac function and diaphragm muscle function following DOX treatment compared to sedentary rats. NIH R01 HL144858, NIH R01 HL146443, NIH HL134621. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Peripheral Neuropathy and Muscle Disorders as Immune-Related Adverse Events

Neurological immune-related adverse events (irAEs) associated with cancer treatment with immune checkpoint inhibitors (ICI) present diverse clinical characteristics. Neurological irAEs affect the peripheral nervous system and muscles more than they affect the central nervous system. Among the various subsets of peripheral neuropathies, polyradiculoneuropathy, which includes Guillain-Barre syndrome and chronic inflammatory demyelinating polyneuropathy, stands out as the most severe form, leading to significant muscle weakness. ICIs can induce dysautonomia, including autoimmune autonomic ganglionopathy. Autonomic neuropathy represents a neurological irAE. Neurological irAEs of neuromuscular junctions include myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS). Diagnosing MG or myositis independently can be challenging when they occur as irAEs. Myocarditis is sometimes observed as an irAE in patients with MG and can cause both severe heart failure and lethal arrhythmias, resulting in fatal outcomes. Anti-Kv1.4 antibodies are biomarkers of the severe form of MG and myocarditis. The administration of ICI in patients with small cell lung cancer increases the risk of LEMS. The distinction between LEMS is an irAE or a manifestation of paraneoplastic neurological syndrome is unclear as both conditions share common immunological mechanisms.

Metabolic characteristics of transmembrane prolyl 4-hydroxylase (P4H-TM) deficient mice

Transmembrane prolyl 4-hydroxylase (P4H-TM) is an enigmatic enzyme whose cellular function and primary substrate remain to be identified. Its loss-of-function mutations cause a severe neurological HIDEA syndrome with hypotonia, intellectual disability, dysautonomia and hypoventilation. Previously, P4H-TM deficiency in mice was associated with reduced atherogenesis and lower serum triglyceride levels. Here, we characterized the glucose and lipid metabolism of P4h-tm−/− mice in physiological and tissue analyses. P4h-tm−/− mice showed variations in 24-h oscillations of energy expenditure, VO2 and VCO2 and locomotor activity compared to wild-type (WT) mice. Their rearing activity was reduced, and they showed significant muscle weakness and compromised coordination. Sedated P4h-tm−/− mice had better glucose tolerance, lower fasting insulin levels, higher fasting lactate levels and lower fasting free fatty acid levels compared to WT. These alterations were not present in conscious P4h-tm−/− mice. Fasted P4h-tm−/− mice presented with faster hepatic glycogenolysis. The respiratory rate of conscious P4h-tm−/− mice was significantly lower compared to the WT, the decrease being further exacerbated by sedation and associated with acidosis and a reduced ventilatory response to both hypoxia and hypercapnia. P4H-TM deficiency in mice is associated with alterations in whole-body energy metabolism, day-night rhythm of activity, glucose homeostasis and neuromuscular and respiratory functions. Although the underlying mechanism(s) are not yet fully understood, the phenotype appears to have neurological origins, controlled by brain and central nervous system circuits. The phenotype of P4h-tm−/− mice recapitulates some of the symptoms of HIDEA patients, making this mouse model a valuable tool to study and develop tailored therapies.

Diffuse Large B-cell Lymphoma Complicated with Anti-3-hydroxy-3-methylglutaryl-Coenzyme A Reductase Immune-mediated Necrotizing Myopathy: A Case Report.

A 75-year-old woman presented with significant muscle weakness after statin use. A muscle biopsy revealed necrotizing myopathy, and the patient tested positive for serum anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibodies, leading to a diagnosis of anti-HMGCR immune-mediated necrotizing myopathy (IMNM). Computed tomography revealed intraperitoneal lymphadenopathy, which was diagnosed as a diffuse large B-cell lymphoma. Immunostaining confirmed HMGCR expression in the lymphoma cells. The patient received chemotherapy and achieved complete remission of the lymphoma, along with nearly complete recovery from IMNM. Although the etiologies of IMNM and lymphoma remain unclear, HMGCR expression in lymphoma cells is likely to be associated with the development of IMNM.

Respiratory muscle strength in stroke: a case-control study.

The aim of the study was to determine the respiratory muscle strength of stroke patients and compare them with healthy individuals. The study was conducted with 171 patients who had a stroke between 2017 and 2021 and 32 healthy controls. Respiratory muscle strength and inspiratory and expiratory mouth pressure (MIP and MEP) were measured using the portable MicroRPM device (Micro Medical, Basingstoke, UK). The stroke group exhibited significantly lower values in both MIP for men (p<0.001) and women (p=0.013) and maximal expiratory pressure for men (p<0.001) and women (p=0.042), compared with the healthy control group. Notably, there was a significant difference in the MIPmen (p=0.026) and MEPmen (p=0.026) values when comparing the reference values, which were calculated based on age and sex, with those of the healthy group. The baseline values calculated according to age for stroke patients were as follows: MIPmen 31.68%, MIPwomen 63.58%, MEPmen 22.54%, and MEPwomen 42.30%. This study highlights the significant respiratory muscle weakness experienced by stroke patients, with gender-specific differences. It highlights the importance of incorporating respiratory assessments and interventions into stroke rehabilitation protocols to improve the overall health and well-being of stroke patients.

Prefrontal cortex hemodynamic activity during a test of lower extremity functional muscle strength in children with cerebral palsy: A functional near-infrared spectroscopy study.

Children with cerebral palsy (CP) exhibit impaired motor control and significant muscle weakness due to a brain lesion. However, studies that assess the relationship between brain activity and performance on dynamic functional muscle strength assessments in CP are needed. The aim of this study was to determine the effect of a progressive lateral step-up test on prefrontal cortex (PFC) hemodynamic activity in children with CP. Fourteen ambulatory children with spastic CP (Gross Motor Function Classification System level I; 5-11 y) and 14 age- and sex-matched typically developing control children completed a progressive lateral step-up test at incremental step heights (0, 10, 15 and 20 cm) using their non-dominant lower limb. Hemodynamic activity in the PFC was assessed using non-invasive, portable functional neuroimaging (functional near-infrared spectroscopy). Children with CP completed fewer repetitions at each step height and exhibited lower PFC hemodynamic activity across step heights compared to controls. Lower PFC activation in CP was maintained after statistically controlling for the number of repetitions completed at each step height. PFC hemodynamic activity was not associated with LSUT task performance in children with CP, but a positive relationship was observed in controls at the most challenging 20 cm step height. The results suggest there is an altered PFC recruitment pattern in children with CP during a highly dynamic test of functional strength. Further studies are needed to explore the mechanisms underlying the suppressed PFC activation observed in children with CP compared to typically developing children.

An odd case of immune-mediated necrotizing myopathy, complicated with sagittal, transverse and sigmoid sinus thrombosis

INTRODUCTION: Immune-mediated necrotizing myopathy (IMNM) is a rare variant of immune-mediated inflammatory myopathy (IMIM) that exhibits a severe prognosis and is unresponsive to conventional treatment. (1,2)Notably, the incidence of immune-mediated inflammatory myopathies (IMIMs) is low, estimated at 1.16 to 19/million/year and only 3-6% of IMIMs are diagnosed as IMNM. (1,3–5). Systemic inflammation has been found to play a crucial role in promoting the onset of cerebral venous thrombosis. (6,7) MATERIAL AND METHODS: We present the case of a 46-years-old Chinese woman, without any known prior pathology, who was referred to the Rheumatology Department for symmetrical, proximal muscle weakness of the limbs, dysphagia for solid food, and weight loss (5 kg within 2 months). The pathologic clinical examination revealed itchy erythematous plaques on the posterior thoracolumbar region and signs of muscle weakness. Laboratory workup showed significant inflammatory syndrome, severe muscle and hepatic cytolysis syndrome, and positivity for thyroid-specific autoantibodies but with normal thyroid function, positivity for antinuclear antibodies (more precisely: SS-A, Ro-52, SS-B), and myositis antibodies (SRP, Ro-52, SAE1, PM-Scl, MDA5). The CT scan of the thoracic, abdominal, and pelvis showed fibrosis of the lungs, hepatic hypertrophy, and an enlarged uterus, further diagnosed by transvaginal ultrasound as adenomyosis. The positive diagnosis is immune-mediated necrotizing myopathy. Differential diagnoses included dermatomyositis, toxic/infectious myositis, hypothyroidism, and neuro-muscular diseases (5,8). The initial treatment was made with glucocorticoids (pulse therapy followed by oral therapy) and immunosuppressants (Mycophenolate Mofetil – stopped because of severe dyspepsia and myelosuppression). After five days of pulse therapy, the patient developed muscle weakness and paresthesia on the left side of the body, and the cerebral CT scan revealed sagittal, transverse, and sigmoid sinus thrombosis. Thrombophilia screening uncovered the positivity of the lupus anticoagulant. (9) RESULTS: The patient was treated with anticoagulants (low molecular weight heparin, and afterward Vitamin K antagonist), low doses of oral glucocorticoids, and immunosuppressant (Methotrexate), without any other adverse event. CONCLUSION: In the presence of the lupus anticoagulant, even though the antiphospholipid syndrome is not confirmed, the only anticoagulant therapy that has proven its efficacy is the Vitamin K antagonist. Immune inflammatory myopathies, like IMNMs, create a significant inflammatory status that leads to hypercoagulability and endothelial injury, which exposes collagen and tissue factors, promoting further platelet aggregation, and can even lead to cerebral thrombosis. (2,6)

Geographic variation in the clinical features of Mohave rattlesnake (Crotalus scutulatus) envenomations reported to the North American Snakebite Registry

The geographic variation of Mohave rattlesnake (Crotalus scutulatus) venom is well established. We reviewed all the Mohave rattlesnake bites reported to the Toxicology Investigators Consortium's North American Snakebite Registry between January 1, 2015 and 12/31/2021. Data reviewed for this study included details regarding the snake encounter, patient demographics, signs and symptoms, treatment, and outcomes. Our objective was to describe the epidemiology, clinical manifestations, and management of Mohave rattlesnake envenomations using prospective data from two geographically distinct sites. There were 20 subjects, including eight nonpregnant females. Ages ranged from seven to 75 years, median age 48. Nine of the bites were managed in Arizona and 11 in California. In Arizona, all envenomated patients had local swelling. None had neurological toxicity. In California, swelling was present in nine patients. Neurological effects were observed in five subjects. Four Arizona patients and one California patient had hypotension requiring treatment. Each site had one patient with thrombocytopenia. An Arizona patient who sustained a bite to the face was intubated. Rhabdomyolysis occurred in two California patients. All envenomated patients received antivenom. Mohave rattlesnakes have the potential to cause significant local and/or systemic toxicity. Neurotoxicity was not observed in envenomations from Mohave rattlesnakes that presumably lack Mohave toxin, but hypotension and gastrointestinal signs were more common than in bites from snakes believed to possess Mohave toxin. Neurological toxicity was limited to paresthesias and fasciculations. Significant skeletal or respiratory muscle weakness was not observed in our study population.

Abstract 16715: Rare or Disregarded; A Case of Autoimmune Myopathy

Introduction: Statin-induced myopathy can present with symptoms ranging from mild myalgia to significant muscle weakness. This case report highlights how statin-induced autoimmune myopathy often goes undiagnosed. Case Presentation: We present a 69 year old male with a past medical history of coronary artery disease who presented with myalgia and progressive proximal muscle weakness for 2 months. On admission, creatinine kinase (CK) level was noted to be elevated at 8323 u/L. Atorvastatin was held on admission and the patient received intravenous (IV) fluid as treatment for presumed rhabdomyolysis. Although CK was trending down, the patient did not show any significant improvement in muscle weakness or myalgia. At this point, myositis was suspected, so a myositis panel including anti-HMG Co-A Reductase antibody was ordered and the patient was started on IV steroids. Anti-HMG Co-A Reductase antibody was positive and the rest of myopathy workup was negative; meanwhile, the patient's muscle weakness significantly improved. The patient was discharged on a methylprednisolone with close outpatient rheumatology follow-up. Discussion: Drug-induced rhabdomyolysis is one of many causes of myalgia. It is crucial to review a patient’s medication list and discontinue any possible medications that are possible offenders. Statin-induced myopathy should also be suspected when typical treatment for rhabdomyolysis is failing. Statin induced autoimmune myopathy is associated with muscle weakness, elevated CK and a positive anti-HMG Co-A Reductase antibody, which requires discontinuation of Statin and initiation of immunosuppressive therapy. Conclusions: This case report highlights the importance of early identification and management of statin-induced autoimmune myopathy as a possible differential diagnosis in patients with muscle weakness, elevated CK levels while on statin therapy who do not respond to IV fluid alone.

PI3KC2β: A promising therapeutic target in myotubular myopathy

Myotubular myopathy is a rare disease of genetic origin characterized by significant muscle weakness leading to respiratory disorders and for which no treatment exists today. In this paper, we show that inhibition of the activity of the enzyme PI3KC2β prevents the development of this myopathy in a mouse model of the disease, thus identifying a therapeutic target to treat myotubular myopathy in humans.

Maximal Respiratory Mouth Pressures Assessment in Stable Chronic Obstructive Pulmonary Disease Patients in a Tertiary Hospital in Southwest Nigeria

Objective: This study aimed to assess the respiratory muscle strength in stable chronic obstructive pulmonary disease (COPD) patients, via measuring maximal respiratory mouth pressures [maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax)] to determine its association with disease severity and quality of life.Material and Methods: The study was a cross-sectional comparative study. A hundred and forty subjects (70 COPD patients and 70 controls) were recruited. Measurements of PImax, PEmax and spirometry were then performed. The health-related quality of life, severity of obstruction and dyspnea in the COPD patients were assessed using the COPD Assessment Test (CAT), post-bronchodilator Forced Expiratory Volume in 1 second (FEV 1) and the modified Medical Research Council (mMRC) dyspnea scale, respectively. Data was analyzed using Statistical Package for the Social Science (SPSS) version 25.0 (SPSS IL USA.).Results: The mean (±S.D.) PImax and PEmax of the COPD patients (31.78±14.40 cmH2O and 54.80±18.89 cmH2O, respectively) were significantly lower (p&lt;0.001) than the controls (80.40±7.50 cmH2O and 95.44±12.52 cmH2O, respectively). Both the PImax and PEmax correlated positively with the FEV1 of the COPD patients (r=0.658 and 0.534, respectively, p&lt;0.001). The PImax and PEmax decreased as the mMRC dyspnea grade worsened (p&lt;0.001). There was a negative correlation between PImax; PEmax and the CAT score of the COPD patients (r=-0.704 and–0.583, respectively, p&lt;0.001).Conclusion: There was significant respiratory muscle weakness in the COPD patients compared with the controls. The respiratory muscle weakness worsened as the airflow obstruction and dyspnea worsened. Respiratory muscle weakness may also add to the negative impact COPD has on the health status of COPD patients.

Brazilian version of the CHOP INTEND scale: cross-cultural adaptation and validation.

Spinal muscular atrophy (SMA) is a rare genetic disease that causes progressive muscle weakness and impacts motor function. The type I is the most severe presentation and affects infants before 6 months old. In addition, the instruments available for assessing motor function have limitations when applied to infants with neuromuscular diseases and significant muscle weakness. To translate, cross-culturally adapt, and validate the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP INTEND) to Brazilian Portuguese. The present study comprised the translation, synthesis of translations, backtranslation, consolidation by a committee of experts, and test of the final version of the CHOP INTEND in 13 patients with SMA type I. We also assessed the content validity and reliability of the translated version. The scale was translated considering semantic, structural, idiomatic, and cultural aspects. All agreement rates were > 0.8, the overall content validity index of the instrument was 0.98, and inter-rater reliability using the intraclass correlation coefficient was 0.998. The Brazilian version of the CHOP INTEND met semantic and technical equivalence criteria with the original version and was valid and reliable for patients with SMA type I.

Nutrition Assessment and Management of Late-Onset Tay-Sachs Disease: A Clinical Case Report.

Tay-Sachs disease is a sphingolipidoses disorder characterized by failure to produce enzymes necessary for the degradation of sphingolipids in lysosomes, which leads to muscle weakness, ataxia, and mental and speech disorders. The treatment for such disorders commonly includes the use of miglustat, a medication that may cause several side effects (e.g., diarrhea and weight loss) that can contribute to the development of malnutrition. To our knowledge, no reports are available in the literature on the nutritional assessment and intervention recommended for those with Tay-Sachs disease. This case report aimed to describe the case of a female patient diagnosed with late-onset Tay-Sachs disease. The patient presented with diarrhea (adverse effect to treatment) and malnutrition when referred to the dietitian. She had significant muscle loss, asthenia, and weakness. The nutritional interventions prescribed were: dietary modification; supplementation with beta-hydroxymethyl-butyrate (HMB); use of lactase enzyme; probiotic (Saccharomyces boulardii); and oral nutritional supplement with low osmolarity. Recommendations aimed to meet the patient's nutritional requirements, including energy needs. In response to the nutrition intervention, the patient progressed with diarrhea cessation, weight recovery, and improvement in physical function measured by the dynamometer. As patients undergoing treatment for Tay-Sachs disease quickly progress to malnutrition, and given the lack of guidelines to inform healthcare providers on nutritional recommendations for this cohort, the description of a case that had positive progression may inform healthcare providers and help to initiate a discussion on the need to conduct research in this field for the development of therapeutic protocols and nutrition recommendations.