Neuromuscular Research Articles

Congenital Myasthenic Syndromes in Belgium: Genetic and Clinical Characterization of Pediatric and Adult Patients

BackgroundCongenital myasthenic syndromes (CMS) are a group of genetic disorders characterized by impaired neuromuscular transmission. CMS typically present at a young age with fatigable muscle weakness, often with an abnormal response after repetitive nerve stimulation (RNS). Pharmacologic treatment can improve symptoms, depending on the underlying defect. Prevalence is likely underestimated. This study reports on patients with CMS followed in Belgium in 2022. MethodsData were gathered retrospectively from the medical charts. Only likely pathogenic and pathogenic variants were included in the analysis. ResultsWe identified 37 patients, resulting in an estimated prevalence of 3.19 per 1,000,000. The patients harbored pathogenic variants in CHRNE, RAPSN, DOK7, PREPL, CHRNB1, CHRNG, COLQ, MUSK, CHRND, GFPT1, and GMPPB. CHRNE was the most commonly affected gene. Most patients showed disease onset at birth, during infancy, or during childhood. Symptom onset was at adult age in seven patients, caused by variants in CHRNE, DOK7, MUSK, CHRND, and GMPPB. Severity and distribution of weakness varied, as did the presence of respiratory involvement, feeding problems, and extraneuromuscular manifestations. RNS was performed in 23 patients of whom 18 demonstrated a pathologic decrement. Most treatment responses were predictable based on the genotype. ConclusionsThis is the first pooled characterization of patients with CMS in Belgium. We broaden the phenotypical spectrum of pathogenic variants in CHRNE with adult-onset CMS. Systematically documenting larger cohorts of patients with CMS can aid in better clinical characterization and earlier recognition of this rare disease. We emphasize the importance of establishing a molecular genetic diagnosis to tailor treatment choices.

Beadex, the Drosophila LIM only protein, is required for the growth of the larval neuromuscular junction.

The appropriate growth of the neurons, accurate organization of their synapses, and successful neurotransmission are indispensable for sensorimotor activities. These processes are highly dynamic and tightly regulated. Extensive genetic, molecular, physiological, and behavioral studies have identified many molecular candidates and investigated their roles in various neuromuscular processes. In this paper, we show that Beadex (Bx), the Drosophila LIM only (LMO) protein, is required for motor activities and neuromuscular growth of Drosophila. The larvae bearing Bx7, a null allele of Bx, and the RNAi-mediated neuronal-specific knockdown of Bx show drastically reduced crawling behavior, a diminished synaptic span of the neuromuscular junctions (NMJ) and an increased spontaneous neuronal firing with altered motor patterns in the central pattern generators (CPGs). Microarray studies identified multiple targets of Beadex that are involved in different cellular and molecular pathways, including those associated with the cytoskeleton and mitochondria, that could be responsible for the observed neuromuscular defects. With genetic interaction studies, we further show that Highwire (Hiw), a negative regulator of synaptic growth at the NMJs, negatively regulates Bx, as the latter's deficiency was able to rescue the phenotype of the Hiw null mutant, HiwDN. Thus, our data indicates that Beadex functions downstream of Hiw to regulate the larval synaptic growth and physiology.

Optimization of an electric field calibration chamber for high-precision measurements for imaging applications

The DEVCOM Army Research Laboratory (ARL) electric field “cage” generates a uniform E-field over a large working volume, along the lines of the IEEE-Std 1308–1994. The end plates are spaced farther apart than the IEEE standard field source, and the fringing fields are controlled by the addition of “guard tubes.” This chamber was originally constructed to calibrate and characterize electric field sensors, and it has been redesigned to support quasi-static electric field imaging applications. A planar array of sensors forms a grounded end plate of the cage and is used to measure distortions in the uniform field generated by the cage due to objects placed inside. However, the array itself distorts this field and introduces significant errors. Several modifications were made to mitigate the errors, including adding nonfunctional “dummy” elements, a border around the array, and a back plane behind it. The parameter space for these additions is very large, since the number of nonfunctional elements, the width of the border, and the size and placement of the back plane can all be tuned independently. Extensive computer modeling was used to explore this parameter space and test thousands of possible designs. The design chosen yields modeled absolute field errors over a 1.2-m × 0.8-m sensing plane that are less than 0.5 % for a uniform ambient field (empty cage), and less than 1 % for a sphere with a 0.5-m radius in an ambient field.

Extracellular Vesicles from NSC-34 MN-like Cells Transfected with Mutant SOD1 Modulate Inflammatory Status of Raw 264.7 Macrophages.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease targeting the brain and spinal cord. Non-neuronal cells, including macrophages, may contribute to the disruption of motor neurons (MNs), neuromuscular junction dismantling and clinical signs of ALS. Understanding the modality and the effect of MNs-macrophage communication is pivotal. Here, we focus on extracellular vesicle (EVS)-mediated communication and, in particular, we analyze the response of macrophages. NSC-34 cells transfected with mutant SOD1 (G93A, A4V, G85R, G37R) and differentiated towards MN-like cells, and Raw 264.7 macrophages are the cellular models of the study. mSOD1 NSC-34 cells release a high number of vesicles, both large-lEVs (300 nm diameter) and small-sEVs (90 nm diameter), containing inflammation-modulating molecules, and are efficiently taken up by macrophages. RT-PCR analysis of inflammation mediators demonstrated that the conditioned medium of mSOD1 NSC-34 cells polarizes Raw 264.7 macrophages towards both pro-inflammatory and anti-inflammatory phenotypes. sEVs act on macrophages in a time-dependent manner: an anti-inflammatory response mediated by TGFβ firstly starts (12 h); successively, the response shifts towards a pro-inflammation IL-1β-mediated (48 h). The response of macrophages is strictly dependent on the SOD1 mutation type. The results suggest that EVs impact physiological and behavioral macrophage processes and are of potential relevance to MN degeneration.

Inter-alpha-trypsin inhibitor heavy chain H3 is a potential biomarker for disease activity in myasthenia gravis

Myasthenia gravis is a chronic antibody-mediated autoimmune disease disrupting neuromuscular synaptic transmission. Informative biomarkers remain an unmet need to stratify patients with active disease requiring intensified monitoring and therapy; their identification is the primary objective of this study. We applied mass spectrometry-based proteomic serum profiling for biomarker discovery. We studied an exploration and a prospective validation cohort consisting of 114 and 140 anti-acetylcholine receptor antibody (AChR-Ab)-positive myasthenia gravis patients, respectively. For downstream analysis, we applied a machine learning approach. Protein expression levels were confirmed by ELISA and compared to other myasthenic cohorts, in addition to myositis and neuropathy patients. Anti-AChR-Ab levels were determined by a radio receptor assay. Immunohistochemistry and immunofluorescence of intercostal muscle biopsies were employed for validation in addition to interactome studies of inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3). Machine learning identified ITIH3 as potential serum biomarker reflective of disease activity. Serum levels correlated with disease activity scores in the exploration and validation cohort and were confirmed by ELISA. Lack of correlation between anti-AChR-Ab levels and clinical scores underlined the need for biomarkers. In a subgroup analysis, ITIH3 was indicative of treatment responses. Immunostaining of muscle specimens from these patients demonstrated ITIH3 localization at the neuromuscular endplates in myasthenia gravis but not in controls, thus providing a structural equivalent for our serological findings. Immunoprecipitation of ITIH3 and subsequent proteomics lead to identification of its interaction partners playing crucial roles in neuromuscular transmission. This study provides data on ITIH3 as a potential pathophysiological-relevant biomarker of disease activity in myasthenia gravis. Future studies are required to facilitate translation into clinical practice.

Gap-junction-mediated bioelectric signaling required for slow muscle development and function in zebrafish.

Bioelectric signaling, intercellular communication facilitated by membrane potential and electrochemical coupling, is emerging as a key regulator of animal development. Gap junction (GJ) channels can mediate bioelectric signaling by creating a fast, direct pathway between cells for the movement of ions and other small molecules. In vertebrates, GJ channels are formed by a highly conserved transmembrane protein family called the connexins. The connexin gene family is large and complex, creating challenges in identifying specific connexins that create channels within developing and mature tissues. Using the embryonic zebrafish neuromuscular system as a model, we identify a connexin conserved across vertebrate lineages, gjd4, which encodes the Cx46.8 protein, that mediates bioelectric signaling required for slow muscle development and function. Through mutant analysis and invivo imaging, we show that gjd4/Cx46.8 creates GJ channels specifically in developing slow muscle cells. Using genetics, pharmacology, and calcium imaging, we find that spinal-cord-generated neural activity is transmitted to developing slow muscle cells, and synchronized activity spreads via gjd4/Cx46.8 GJ channels. Finally, we show that bioelectrical signal propagation within the developing neuromuscular system is required for appropriate myofiber organization and that disruption leads to defects in behavior. Our work reveals a molecular basis for GJ communication among developing muscle cells and reveals how perturbations to bioelectric signaling in the neuromuscular system may contribute to developmental myopathies. Moreover, this work underscores a critical motif of signal propagation between organ systems and highlights the pivotal role of GJ communication in coordinating bioelectric signaling during development.

Neuromuscular Emergencies.

This article aims to familiarize the reader with the clinical approach, diagnostic considerations, and treatment strategies for patients presenting with abrupt-onset or acutely worsening weakness due to neuromuscular disorders. Neuromuscular weakness is often the result of an inflammatory process. In recent years, there has been growing recognition of pathologic antibodies that cause neuromuscular injury. This has allowed clinicians to make a more accurate diagnosis. Additionally, neuromuscular junction disorders and myopathies are increasingly identified as the adverse effects of novel anticancer therapies, namely immune checkpoint inhibitors. More data are being incorporated into frameworks for neuroprognostication after neuromuscular emergencies, especially for commonly encountered disorders such as Guillain-Barré syndrome. Care of patients with neuromuscular emergencies requires prompt attention to respiratory status. Once supportive measures are in place to protect the airway and facilitate effective ventilation, diagnostic considerations should hinge on appropriate neurologic localization. Aggressive immunosuppression is often required for immune-mediated neuromuscular disorders, and clinicians must be thoughtful in selecting a strategy that best aligns with each patient's risk factors and comorbidities.

Neuronal LRP4 directs the development, maturation and cytoskeletal organization of Drosophila peripheral synapses.

Synaptic development requires multiple signaling pathways to ensure successful connections. Transmembrane receptors are optimally positioned to connect the synapse and the rest of the neuron, often acting as synaptic organizers to synchronize downstream events. One such organizer, the LDL receptor-related protein LRP4, is a cell surface receptor that has been most well-studied postsynaptically at mammalian neuromuscular junctions. Recent work, however, identified emerging roles, but how LRP4 acts as a presynaptic organizer and the downstream mechanisms of LRP4 are not well understood. Here, we show that LRP4 functions presynaptically at Drosophila neuromuscular synapses, acting in motoneurons to instruct pre- and postsynaptic development. Loss of presynaptic LRP4 results in multiple defects, impairing active zone organization, synapse growth, physiological function, microtubule organization, synaptic ultrastructure and synapse maturation. We further demonstrate that LRP4 promotes most aspects of presynaptic development via a downstream SR-protein kinase, SRPK79D. These data demonstrate a function for presynaptic LRP4 as a peripheral synaptic organizer, highlight a downstream mechanism conserved with its CNS function in Drosophila, and underscore previously unappreciated but important developmental roles for LRP4 in cytoskeletal organization, synapse maturation and active zone organization.

Clinical outcomes, demographics and associative analysis of lung cancer patients with Lambert-Eaton myasthenic syndrome: Insights from the National Inpatient Sample (NIS) database.

e20134 Background: Lambert-Eaton myasthenic syndrome (LEMS) is a rare neuromuscular junction disorder that may present as a paraneoplastic syndrome or a primary autoimmune disorder. Approximately 60% of LEMS patients have an underlying tumor, with the paraneoplastic form predominantly associated with small cell lung cancer (SCLC). Understanding the clinical outcomes and risks associated in lung cancer patients with LEMS is crucial in effective management of such patients. Methods: This retrospective study utilized inpatient hospitalization data from the National Inpatient Sample (NIS) between January 1, 2016, and December 31, 2019. Data of patients with a primary or secondary discharge diagnosis of lung cancer (ICD10-CM codes C34, C78.0, C46.5, D02.2) were obtained. Then, out of this population, we identified Lambert-Eaton myasthenic syndrome with ICD-10 codes (G70.80, G70.81, G73.1). The objective was to run a descriptive analysis of clinical outcomes, risks, demographics and associations of LEMS in patients with lung cancer. Results: A total of 204 cases of lung cancer hospitalizations with LEMS were analyzed. The mean age was 68.23 years, with a slight female (51.72%) preponderance as compared to male (48.28%). Race distribution revealed increased prevalence in White Caucasians (83%), followed by Black (7%), Hispanic (4.5%), Asian or Pacific Islander (3%), Native American (0.5%), and Other (2%). The majority were covered by Medicare (66.33%), followed by private insurance (26.13%). The mortality rate was 8.9%, with a mean length of stay of 10.35 days and mean hospital charges of $118,676. Clinical outcomes and risks were analyzed, with sepsis occurring in 17.6% of cases, pneumonia in 22.5%, and acute respiratory failure in 26.9%. Intubation/mechanical ventilation was necessary in 18.1% of cases. The incidence of urinary tract infection (UTI) was 16.7%, acute kidney injury (AKI) was 17.2%, and venous thromboembolism (VTE) was 6.4%. Additionally, interventions such as intravenous immunoglobulin (IVIG) therapy and blood transfusions were also noted. Conclusions: This study provides insights into the demographic characteristics and clinical outcomes of lung cancer patients with Lambert-Eaton myasthenic syndrome (LEMS). The findings highlight the need for comprehensive management strategies targeting associated complications like acute respiratory failure, intubation and need for mechanical ventilation, pneumonia, UTI, AKI, and VTE to improve patient outcomes, quality of care and effective patient education with regards to their diagnosis of LEMS in lung cancer.

Synthesis and Biological Evaluation of Novel MB327 Analogs as Resensitizers for Desensitized Nicotinic Acetylcholine Receptors after Intoxication with Nerve Agents

Poisoning with organophosphorus compounds, which can lead to a cholinergic crisis due to the inhibition of acetylcholinesterase and the subsequent accumulation of acetylcholine (ACh) in the synaptic cleft, is a serious problem for which treatment options are currently insufficient. Our approach to broadening the therapeutic spectrum is to use agents that interact directly with desensitized nicotinic acetylcholine receptors (nAChRs) in order to induce functional recovery after ACh overstimulation. Although MB327, one of the most prominent compounds investigated in this context, has already shown positive properties in terms of muscle force recovery, this compound is not suitable for use as a therapeutic agent due to its insufficient potency. By means of in silico studies based on our recently presented allosteric binding pocket at the nAChR, i.e. the MB327-PAM-1 binding site, three promising MB327 analogs with a 4-aminopyridinium ion partial structure (PTM0056, PTM0062 and PTM0063) were identified. In this study, we present the synthesis and biological evaluation of a series of new analogs of the aforementioned compounds with a 4-aminopyridinium ion partial structure (PTM0064-PTM0072), as well as hydroxy-substituted analogs of MB327 (PTMD90-0012 and PTMD90-0015) designed to substitute entropically unfavorable water clusters identified during molecular dynamics simulations. The compounds were characterized in terms of their binding affinity towards the aforementioned binding site by applying the UNC0642 MS Binding Assays and in terms of their muscle force reactivation in rat diaphragm myography. More potent compounds were identified compared to MB327, as some of them showed a higher affinity towards MB327-PAM-1 and also a higher recovery of neuromuscular transmission at lower compound concentrations. To improve the treatment of organophosphate poisoning, direct targeting of nAChRs with appropriate compounds is a key step, and this study is an important contribution to this research.

A Novel Bipedicular Dissociation Fracture Pattern of Vertebral Osteoporotic Fractures of the Elderly.

CVFs are common, with several classification systems available. We have encountered osteoporotic vertebral fractures (OVFs) with PDF, a never-described fracture pattern.This study evaluates this unique fracture's characteristics. Retrospective study of surgically treated OVFs during 2016 to 2020. Of 105 patients, 85 had classifiable OVFs and 20 had uni-PDF (n = 10, 9.5%) or bi-PDF (n = 10, 9.5%). Both cohorts mainly had single vertebral fractures and upper end plate involvement with cleft sign found in 30% of PDFs versus 15.3% of OVFs (P < 0.001), higher incidence of burst fractures (40% vs. 25.9%; P < 0.001). Posterior vertebral body collapse was higher for PDFs (13.2 ± 9.3% vs. 18.3 ± 8.5%; P = 0.02). Most OVFs underwent balloon kyphoplasty (BKP) (94%). Most bi-PDFs were regarded unstable; six patients underwent PSF (2 short PSF, 1 PSF + BKP, and 3 BKP with intravertebral pedicular lag screws at the fractured vertebra). Half of the bi-PDFs underwent BKP-developed nonunion. Our study is novel in describing an unrecognized OVF pattern disregarded in current classification systems. We found notable differences in fracture characteristics, prefracture functional status, and surgical results between OVF and PDF cohorts. We suggest adding this fracture pattern as a unique OF-4 subtype or a specific entity between OF-4 and 5, with uni-PDF as type A and bi-PDF as type B.

A bioinspired neuromuscular system enabled by flexible electro-optical N2200 nanowire synaptic transistor

Mimicking the functional traits of the muscle system evolves the development of the neuromorphic prosthetic limbs. Herein, a bioinspired neuromuscular system was constructed by connecting an information processor that uses a flexible electro-optical synaptic transistor (FNST) to an effector that uses artificial muscle fibers. In this system, the response of artificial muscle fibers, which imitate the movement of biological muscle fibers, is manipulated by neuromorphic synaptic devices. The FNST is regulated by light pulses and electrical spikes to emulate biological synaptic functions, and thereby applied in secure communication. The feasibility of n-type organic nanowires acting as the channels for neuromorphic devices was demonstrated. Attributing to the flexibility of the n-type organic semiconductor N2200 nanowires, the current of the FNST retains >85% of its initial value after the 5000 bending cycles to radius = 1 cm. The tolerance of bending of the FNST implies its potential applications in wearable electronics. This work offers an approach to potentially advancing electronic skin, neuro-controlled robots, and neuromorphic prosthetic limbs.

Age related progression of lower limb coordination during gait in children with cerebral palsy without a history of surgical intervention

Walking requires precise movement between body segments, referred to as intersegmental coordination, which is an important factor in efficient motor performance. For children with cerebral palsy (CP), who often demonstrate an impaired neuromuscular system, intersegmental coordination has been shown to be different when compared to their typically developed (TD) peers. However, how intersegmental coordination changes over time in these children is unclear. The aim of this study was to quantify age-related changes in intersegmental coordination in children with bilateral CP without a history of surgical intervention and to compare to control groups of children with TD of similar age, weight, and height. A retrospective analysis of 162 children with bilateral CP who had a baseline and follow-up 3D gait assessment, and no history of surgical intervention, was conducted. Two age, weight, and height control groups of children with TD were included. A full 3-dimensional kinematic analysis was performed, and continuous relative phase analysis of the thigh-shank and shank-foot, while walking at a self-selected walking speed, was used to measure intersegmental coordination. Differences were present for children with CP compared to children with TD at baseline for thigh-shank intersegmental coordination. However, children with CP demonstrated a change over time with a move towards TD patterns at follow-up assessment. This study provides insights into the acquisition and stabilisation of intersegmental coordination between children with CP and TD.

Littorina snails and Microphallus trematodes: Diverse consequences of the trematode-induced metabolic shifts.

The intricate relationships between parasites and hosts encompass a wide range of levels, from molecular interactions to population dynamics. Parasites influence not only the physiological processes in the host organism, but also the entire ecosystem, affecting mortality of individuals, the number of offspring through parasitic castration, and matter and energy cycles. Understanding the molecular mechanisms that govern host-parasite relationships and their impact on host physiology and environment remains challenging. In this study, we analyzed how infection with Microphallus trematodes affects the metabolome of two Littorina snail species inhabiting different intertidal zone shore levels. We applied non-targeted GC-MS-based metabolomics to analyze biochemical shifts induced by trematode infection in a host organism. We have identified changes in energy, amino acid, sugar, and lipid metabolism. In particular, we observed intensified amino acid catabolism and nitrogenous catabolites (glutamine, urea) production. These changes primarily correlated with infection and interspecies differences of the hosts rather than shore level. The changes detected in the host metabolism indicate that other aspects of life may have been affected, both within the host organism and at a supra-organismal level. Therefore, we explored changes in microbiota composition, deviations in the host molluscs behavior, and acetylcholinesterase activity (ACE, an enzyme involved in neuromuscular transmission) in relation to infection. Infected snails displayed changes in their microbiome composition. Decreased ACE activity in snails was associated with reduced mobility, but whether it is associated with trematode infection remains unclear. The authors suggest a connection between the identified biochemical changes and the deformation of the shell of molluscs, changes in their behavior, and the associated microbiome. The role of parasitic systems formed by microphallid trematodes and Littorina snails in the nitrogen cycle at the ecosystem level is also assumed.

In vitro modeling of skeletal muscle ischemia-reperfusion injury based on sphere differentiation culture from human pluripotent stem cells

Skeletal muscle ischemia-reperfusion (IR) injury poses significant challenges due to its local and systemic complications. Traditional studies relying on two-dimensional (2D) cell culture or animal models often fall short of faithfully replicating the human in vivo environment, thereby impeding the translational process from animal research to clinical applications. Three-dimensional (3D) constructs, such as skeletal muscle spheroids with enhanced cell-cell interactions from human pluripotent stem cells (hPSCs) offer a promising alternative by partially mimicking human physiological cellular environment in vivo processes. This study aims to establish an innovative in vitro model, human skeletal muscle spheroids based on sphere differentiation from hPSCs, to investigate human skeletal muscle developmental processes and IR mechanisms within a controlled laboratory setting. By eticulously recapitulating embryonic myogenesis through paraxial mesodermal differentiation of neuro-mesodermal progenitors, we successfully established 3D skeletal muscle spheroids that mirror the dynamic colonization observed during human skeletal muscle development. Co-culturing human skeletal muscle spheroids with spinal cord spheroids facilitated the formation of neuromuscular junctions, providing functional relevance to skeletal muscle spheroids. Furthermore, through oxygen-glucose deprivation/re-oxygenation treatment, 3D skeletal muscle spheroids provide insights into the molecular events and pathogenesis of IR injury. The findings presented in this study significantly contribute to our understanding of skeletal muscle development and offer a robust platform for in vitro studies on skeletal muscle IR injury, holding potential applications in drug testing, therapeutic development, and personalized medicine within the realm of skeletal muscle-related pathologies.

Mechanism of Purinergic Regulation of Neurotransmission in Mouse Neuromuscular Junction: The Role of Redox Signaling and Lipid Rafts.

Acetylcholine is the main neurotransmitter at the vertebrate neuromuscular junctions (NMJs). ACh exocytosis is precisely modulated by co-transmitter ATP and its metabolites. It is assumed that ATP/ADP effects on ACh release rely on activation of presynaptic Gi protein-coupled P2Y13 receptors. However, downstream signaling mechanism of ATP/ADP-mediated modulation of neuromuscular transmission remains elusive. Using microelectrode recording and fluorescent indicators, the mechanism underlying purinergic regulation was studied in the mouse diaphragm NMJs. Pharmacological stimulation of purinoceptors with ADP decreased synaptic vesicle exocytosis evoked by both low and higher frequency stimulation. This inhibitory action was suppressed by antagonists of P2Y13 receptors (MRS 2211), Ca2+ mobilization (TMB8), protein kinase C (chelerythrine) and NADPH oxidase (VAS2870) as well as antioxidants. This suggests the participation of Ca2+ and reactive oxygen species (ROS) in the ADP-triggered signaling. Indeed, ADP caused an increase in cytosolic Ca2+ with subsequent elevation of ROS levels. The elevation of [Ca2+]in was blocked by MRS 2211 and TMB8, whereas upregulation of ROS was prevented by pertussis toxin (inhibitor of Gi protein) and VAS2870. Targeting the main components of lipid rafts, cholesterol and sphingomyelin, suppressed P2Y13 receptor-dependent attenuation of exocytosis and ADP-induced enhancement of ROS production. Inhibition of P2Y13 receptors decreased ROS production and increased the rate of exocytosis during intense activity. Thus, suppression of neuromuscular transmission by exogenous ADP or endogenous ATP can rely on P2Y13 receptor/Gi protein/Ca2+/protein kinase C/NADPH oxidase/ROS signaling, which is coordinated in a lipid raft-dependent manner.

Verification of the analytical performance of the serum magnesium assay on Abbott Architect ci8200

Magnesium is recognized as the fourth most important cation in the body and the second most abundant intracellular cation, following potassium. Its physiological significance lies in its capacity to form complexes with crucial intracellular anionic ligands, notably ATP, and its ability to compete with calcium for specific binding sites on proteins and cell membranes. Over 300 enzyme reactions rely on magnesium. The concentration of free magnesium within cells determines the magnesium content of these enzymes. Magnesium influences myocardial contraction and the electrical activity of myocardial cells, as well as the specialized conduction systems of the fetus, by modulating the transmembrane movements of ions like sodium, potassium, and calcium. Furthermore, magnesium can affect the contractility of vascular smooth muscle, and alterations in intracellular magnesium levels may impact cell proliferation or contraction. Magnesium is involved in nucleic acid and protein metabolism, intermediary metabolism, energy production, and consumption reactions, and it plays specific roles in various physiological systems such as the neuromuscular and cardiovascular systems. Our research aims to assess the analytical accuracy of the serum magnesium assay method utilizing an Abbott kit on the Architect ci8200 automated system in the biochemistry laboratory of Mohammed VI University Hospital of Oujda. The evaluation of the kit's analytical accuracy was conducted within the flexible scope A by conducting a performance analysis on the Architect ci8200. We examined repeatability, reproducibility, measurement imprecision, and compared results between two Architect ci8200 instruments. All findings align with the acceptability criteria recommended by the supplier and the Valtec protocol of the Société Française de Biologie Clinique (SFBC), indicating overall satisfactory outcomes for the study. The Architect ci8200 automated system demonstrated satisfactory analytical performance for reliably determining serum magnesium levels. Method verification in medical laboratories is essential to guarantee the accuracy, precision, and reliability of test results. Verification entails confirming that the test method used is suitable for its intended purpose, yields result consistent with the claimed performance characteristics, and meets the laboratory's quality control and quality assurance standards.

Effects of Intramuscular Electrical Stimulation for Treatment of Non-Traumatic Shoulder Pain

Non-traumatic shoulder pain is the third most common cause of consultations for musculoskeletal pain in primary health care. It is one of the common musculoskeletal conditions of the shoulder which may develop sensory-motor and autonomic dysfunctions at the various level of the neuromuscular system. The objective of the study to find out the Effects of Intramuscular Electrical Stimulation for Treatment of Non-Traumatic Shoulder Pain. The pain and dysfunction caused by NSP were primarily treated with physical therapy and pharmacological agents in order to achieve pain free movements. However, in recent years intramuscular electrical stimulation (IMES) with conventional electrode placement was used by researchers to maximize therapeutic values. But, in this study an inverse electrode placement was used to deliver electrical impulses intramuscularly to achieve neuro-modulation at the various level of the nervous system. Nine patients with NSP were treated with intramuscular electrode stimulation using inversely placed electrodes for a period of three weeks. All nine subjects recovered from their shoulder pain and disability within the few weeks of intervention. So, this IMES may be more appropriate for treatment approach for Non traumatic shoulder pain management.

Neuromuscular junction in amyotrophic lateral sclerosis. Is there more to follow?

Background. Amyotrophic lateral sclerosis (ALS) causes progressive degeneration of upper motor neurons in the cortex, and lower motor neurons in the spine. In addition, it is unclear where motor neuron dysfunction begins and what causes motor neuron degeneration: whether it is the dying forward process or the dying back phenomenon where motor neuron degeneration begins distally at the nerve terminal or at the neuromuscular junction and progresses toward the cell body, is still a matter of debate. Materials and methods. Are there neuromuscular junction disorders in the early stages of ALS? To answer this, we described 5 patients with ALS presented at Petre Sarajishvili Institute of Neurology in 2018–2022, 3 males and 2 females aged 50–61 years. ALS diagnosis was based on clinical signs, the Gold Coast criteria, electromyography (Awaji), neuroimaging, blood and urine tests. At the early stage of the disease, only asymmetric ptosis and diplopia were noted, which did not improve on pyridostigmine or steroids. Results. We studied patients’ anamnesis, physical data, evaluated their mental, cognitive functions and neurological status. We have also interviewed family members, as it was often difficult for the patient to accurately describe the symptoms. Acetylcholine receptor antibodies were mildly positive only in one patient. Thymoma was excluded. The neurophysiological study showed only marked neuromuscular transmission failure in orbicularis oculi, there were no clinical and electromyographic signs of motor neuron damage. Conclusions. Approximately 2 years later, all five patients developed clinical and electromyographic signs of ALS. In the present study, neuromuscular junction disorders are found to play an important role in the pathogenesis of ALS and may serve as a useful early diagnostic marker.

Seismic cyclic test of perforated replaceable link for eccentrically braced frames

This study introduces a design comprising a unweakened link and four variants of perforated replaceable links, denoted as specimens RX1 (unweakened link), RX2 and RX3 (with circular holes of 50 mm diameter on the web), RX4 and RX5 specimens (with elliptical holes on the web), and RX6 and RX7 specimens (with weakened flanges and circular holes of 50 mm and 80 mm diameter on the web). Seven link specimens underwent cyclic loading tests. RX1 ultimately failed due to tearing of the weld at the connection between the flange and the end plate, while RX2 to RX7 exhibited deformation concentrated within the energy dissipating region, ceasing loading upon failure of this region, demonstrating enhanced safety and stability. All specimens exhibited relatively full hysteretic curves, with a decrease in the area of hysteretic curves corresponding to an increase in the web perforation ratio. The overstrength coefficient for specimen RX1 ranged from 1.81 to 1.82, while for specimens RX2 to RX7, it ranged from 1.80 to 3.65. Not only were the overstrength coefficients greater than RX1, but also the cumulative energy dissipation was higher than RX1. This indicates that RX2 to RX7 can accommodate larger plastic deformations, effectively utilizing plastic deformation for energy dissipation, thereby exhibiting superior safety. Moreover, an increase in web perforation ratio and weakening of the flanges resulted in a decrease in the overstrength coefficient, load-bearing capacity, and plastic deformation capacity of the specimens. Ductility decreased with increasing web perforation ratio but increased with flange weakening. Additionally, through analysis of link replacement time and residual rotation of links after unloading, it was observed that perforated replaceable links exhibited favorable replaceability.