Muscles, Volume 3, Issue 1 (March 2024) – 10 articles

SYNE2 mutations have been associated with skeletal and cardiac muscle diseases, including Emery-Dreifuss muscular dystrophy (EDMD). Here, we present a 70-year-old male patient with muscle pain and elevated serum creatine kinase levels in whom whole-exome sequencing revealed a novel heterozygous SYNE2 splice site mutation (NM_182914.3:c.15306+2T>G). This mutation is likely to result in the loss of the donor splice site in intron 82. While a diagnostic muscle biopsy showed unspecific myopathological findings, immunofluorescence analyses of skeletal muscle and dermal cells derived from the patient showed nuclear shape alterations when compared to control cells. In addition, a significantly reduced nesprin-2 giant protein localisation to the nuclear envelope was observed in patient-derived dermal fibroblasts. Our findings imply that the novel heterozygous SYNE2 mutation results in a monoallelic splicing defect of nesprin-2, thereby leading to a rare cause of myalgia and hyperCKemia. Full article

This study’s primary objective was to examine the differences in body composition, abdominal strength, absolute and relative power, handgrip strength, one repetition maximum for squat and bench press, and the maximum count of push-up and sit-up repetitions executed within a minute across different age cohorts of firefighters. Furthermore, this study aimed to evaluate the age-related differences in firefighters’ completion times of six firefighting tasks. Eighty-four male volunteer firefighters (age 33.79 ± 6.97 years) were grouped into three age categories, 20–30 years, 31–40 years, and 41–50 years, and underwent the aforementioned evaluations. One-way analysis of variance (MANOVA) revealed that age exerts a statistically significant influence (p < 0.001) on body fat percentage, waist circumference, and waist-to-hip ratio. Furthermore, age significantly affected the overall time of the ability test (p < 0.001) and the duration required to accomplish each individual task (p < 0.001). Additionally, age significantly affected abdominal strength, relative power (as measured by the step test), and the maximum count of push-up and sit-up repetitions performed within a minute. These outcomes support earlier research indicating an age-associated decrement in physical fitness parameters among firefighters. It is recommended that firefighters prioritize maintaining strength and endurance of the abdominal muscles, upper body muscular endurance, and a healthy body weight. The emphasis on specific muscular groups is essential for improving task performance within this profession. Full article

This comprehensive review focuses on the dynamics of branched-chain amino acids (BCAAs) metabolism and its clinical implications in chronic liver disease, with emphasis on the emerging concept of muscle–liver crosstalk. BCAAs, indispensable for protein synthesis and metabolic pathways, undergo unique tissue-specific processing in skeletal muscle and liver. The liver, responsible for amino acid metabolism, plays a distinctive role in sensing BCAAs catabolism, influencing glucose regulation and contributing to the systemic metabolism of BCAAs. Within the context of chronic liver disease, compromised liver metabolism becomes evident through amino acid abnormalities, particularly in the decrease of the Fischer ratio (BCAAs/aromatic amino acids concentrations in plasma). This reduction becomes important in assessing the severity of liver dysfunction due to its associations with adverse outcomes, including increased mortality and complications related to the liver disease. BCAAs supplementation, as explored in this review, emerges as a promising avenue, displaying positive effects on skeletal muscle mass, strength, and overall nutritional status in cirrhosis management. Understanding this interplay offers insights into therapeutic strategies for chronic liver diseases, exploring the way for precision interventions in clinical practice. Full article

Muscle strength and mass strongly influence performance. The role of the trunk, upper limbs, and lower limbs in a specific performance is important but unclear in terms of muscle strength, muscle mass, and the degree of influence of each part. Standing long jump is a performance that produces results by not only the muscles of the lower limbs working together but also the entire body, including the trunk and upper limbs. To determine the influence of muscle strength and the mass of each body part on standing long jump, 31 healthy young adults (18 males and 13 females) participated in this study. Abdominal trunk muscle strength, grip strength, and knee extension muscle strength were measured, each of which was defined as trunk, upper limb, and lower limb muscle strength. The trunk, upper limb, and lower limb muscle masses were measured using a body composition analyzer. Performance was measured using the standing long jump test (jumping power). Factors influencing standing long jump were examined. A multiple regression analysis revealed that trunk (β = 0.367, p = 0.006) and upper limb (β = 0.608, p < 0.001) muscle strength values were extracted for standing long jump (adjusted R² = 0.574, p < 0.01). Trunk and upper limb muscle strength influence standing long jumps. Full article

Pleural mesothelioma (PM) is a tumor related to adverse prognosis. The PM WHO classification has mainly identified three major subtypes of PM which are epithelioid, biphasic, and sarcomatoid. Sarcopenia is a medical issue related to a reduction in muscle mass and strength. It represents a major health issue globally because it is related to adverse effects such as hospitalization, increased length of stay, disability, increased morbidity and mortality and augmented health care expenditures. In this literature review, we attempted to examine the upcoming association between sarcopenia and PM. As recorded by the current literature, muscle loss in PM subjects was related to poorer survival and lower levels of activity. Subjects with PM had increased rates of pre-sarcopenia and malnutrition, while pre-sarcopenia was related to worse activity levels, and malnutrition was related to worse quality of life (QoL). Both tumor volume and sarcopenia were related to long-term mortality in surgically treated PM subjects, while sarcopenia was present both pre-operatively and post-operatively in these subjects. In addition, post-operative sarcopenic subjects showed a decreased 3-year overall survival (OS) in comparison with those who did not have sarcopenia, while pre-operative sarcopenia was importantly related to an increased rate of post-operative adverse outcomes. More studies are needed to validate these claims. Full article

Eculizumab is a monoclonal antibody blocking the terminal complement protein C5. As demonstrated in the phase III randomized, placebo-controlled, REGAIN clinical trial, eculizumab is efficacious in acetylcholine receptor antibody (AChR-Ab)-positive refractory generalized myasthenia gravis (gMG) (Myasthenia Gravis Foundation of America—MGFA class II–IV). It has not been studied in severe myasthenic exacerbation or myasthenic crisis (MGFA V). A 73-year-old man diagnosed with myasthenia gravis AChR-Ab positivity came to our observation for symptoms of bulbar and ocular weakness and unresponsiveness or intolerability to conventional immunosuppressive therapies (prednisone and azathioprine). Due to the recurrent clinical worsening with intubation over a short-term period, the patient was treated with eculizumab. After 15 days of eculizumab treatment, we observed a significant recovery of clinical condition. We discharged the patient to an outpatient regimen, where he is continuing with maintenance doses of eculizumab and slowly tapering steroid intake. The use of eculizumab in myasthenic crises is still anecdotal. Our case aims to provide eculizumab benefit for refractory severe gMG in a practical, real-world setting beyond the criteria of the REGAIN study. Further studies are needed to evaluate the efficacy and safety of eculizumab in myasthenic crises. Full article

Background: Approximately 90% of scoliosis cases are adolescent-idiopathic (AIS). From the first appearance of scoliosis at 10–14 years of age until the age of 18, the spine is most vulnerable to deterioration; young, growing people are most susceptible to the worsening of one or more scoliotic curves. An effective non-surgical means of remediation would be welcome. Design: This was a randomized, controlled, two-arm study assessing the safety and efficacy of combining incobotulinum injections with yoga to reverse lumbar and thoracolumbar AIS. Methods: In a private clinic setting, non-pregnant, healthy 12–18 year-olds were either taught a symmetrical “placebo” yoga pose (control sub-group 1), performed the side plank (Vasisthasana) three times daily with a placebo injection (control sub-group 2) or performed the three-times-daily side plank with a botulinum injection (intervention group 3). Injection: For the injection, 33 IU of incobotulinumtoxin type A (Xeomin) was injected into the concave-side lumbar paraspinals and quadratus lumborum at L2–3 and the psoas muscle at L3–4, or participants were injected similarly with a placebo. Randomization was achieved using random.org. Objective: The objective was to determine whether the treatment of muscular asymmetry with botulinum toxin injections and side planks is safe and effective in AIS. Results/Outcome: Eleven intervention and thirteen placebo patients (Groups 1 + 2), who were 12–18 years old, completed the three-month study. Mean daily side plank time = 165 s. The mean initial lumbar curvature was 36.9 degrees (SD 14.36), (p < 0.0001); the mean Group 3 curvature at 3 weeks was 29.5 degrees (SD 14.23) (p < 0.0001); and the mean Group 3 curvature at 3 months was 26.0 degrees (SD 12.81). Onset vs. 3-month value: p < 0.0001. Harms were limited to one patient in Group 2 and one in Group 3, who complained of transient shoulder pain and supported themselves temporarily on their forearm instead of the palm of the extended hand. Conclusion: Muscle strength asymmetry appears to be relevant to AIS treatment. Incobotulinum injections combined with side planks performed with the convex side downward may be more effective in reversing lumbar AIS than placebo exercises or side planks and placebo injections. Full article

The use of electromyographic biofeedback (EMG-BF) in the rehabilitation of injuries has been widely referenced in the psychological literature. However, despite some pioneering work in the field of sports, its use in the rehabilitation of sports injuries has hardly been explored. A case of two professional soccer players who each suffered a distal radius fracture is presented here. Parallel to the rehabilitation plan established by medical services, an intervention strategy using EMG-BF was established. An EMG-BF intervention was performed on the brachioradialis muscle with the aim of improving the voluntary control of its electromyographic activity. The study protocol was registered with the identifier NCT05376072. An ABA design was used. In each session, a pre- and postline was recorded to determine the EMG gain acquired at each point of the session. After six sessions, the intervention was terminated. One more follow-up session was performed. The results obtained indicated the efficacy of the intervention; a statistically significant increase in muscle activity in the brachioradialis muscle was observed. Full article

An 18-year-old man presented with slowly progressive infancy-onset spasticity of the lower limbs and cerebellar ataxia, associated with painless strabismus, intellectual disability, urinary incontinence, bilateral progressive visual loss, and cognitive decline since early adolescence. A neurological examination disclosed spastic dysarthria, left eye divergent strabismus, bilateral ophthalmoparesis, impaired smooth pursuit, severe spastic paraparesis of the lower limbs with global brisk tendon reflexes, bilateral extensor plantar responses, and bilateral ankle clonus reflex. Bilateral dysdiadochokinesia of the upper limbs, Stewart-Holmes rebound phenomenon, bilateral dysmetria, and a bilateral abnormal finger-to-nose test were observed. Markedly reduced bilateral visual acuity (right side 20/150, left side 20/400) and moderate to severe optic atrophy were detected. Neuroimaging studies showed cerebellar atrophy and bilateral optic nerves and optic tract atrophy as the main findings. As a complicated Hereditary Spastic Paraplegia, autosomal dominant Spinocerebellar Ataxia, or inherited neurometabolic disorders were suspected, a large next-generation sequencing-based gene panel testing disclosed the heterozygous pathogenic variant c.162-1G>A in intron 1 of the PNPT1 gene. A diagnosis of PNPT1-related spastic ataxia was established. Clinicians must be aware of the possibility of PNPT1 pathogenic variants in cases of spastic ataxia and spastic paraplegias that are associated with optic atrophy and marked cognitive decline, regardless of the established family history of neurological compromise. Full article