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Cholesterol is one of the major components of plasma membrane, where its distribution is nonhomogeneous and it participates in lipid raft formation. In skeletal muscle cholesterol and lipid rafts seem to be important for excitation-contraction coupling and for neuromuscular transmission, involving cholesterol-rich synaptic vesicles. In the present study, nerve and muscle stimulation-evoked contractions were recorded to assess the role of cholesterol in contractile function of mouse diaphragm. Exposure to cholesterol oxidase (0.2 U/ml) and cholesterol-depleting agent methyl-β-cyclodextrin (1 mM) did not affect markedly contractile responses to both direct and indirect stimulation at low and high frequency. However, methyl-β-cyclodextrin at high concentration (10 mM) strongly decreased the force of both single and tetanus contractions induced by phrenic nerve stimulation. This decline in contractile function was more profoundly expressed when methyl-β-cyclodextrin application was combined with phrenic nerve activation. At the same time, 10 mM methyl-β-cyclodextrin had no effect on contractions upon direct muscle stimulation at low and high frequency. Thus, strong cholesterol depletion suppresses contractile function mainly due to disturbance of the neuromuscular communication, whereas muscle fiber contractility remains resistant to decline. [ABSTRACT FROM AUTHOR]

An unusually large amplitude spontaneous miniature endplate potentials (gMEPPs) occur naturally at low frequency at the vertebrate neuromuscular junction. Unlike the normal miniature endplate potentials (nMEPPs), these gMEPPs have long duration and long time to peak. More strikingly, gMEPPs seem to be independent of extracellular and intracellular Ca+2. and have a greater temperature sensitivity than nMEPPs. They are potentiated by tetrodotoxin but inhibited by acetylcholine (ACh) receptor blockers indicating ACh is the neurotransmitter responsible for gMEPPs. The frequency of gMEPPs is greatly increased in muscles weakened by various drugs, toxins or disease conditions suggesting that gMEPPs may be a part of possible neurotrophic mechanism to preserve effective neuromuscular transmission when the normal function is compromised. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Methods Results Discussion In motor nerve conduction studies (MNCS), proximal stimulation should give a longer duration and lower amplitude compound muscle action potential (CMAP) due to higher temporal dispersion. Yet the CMAP waveforms at the distal and proximal stimulation sites appear remarkably similar. The objective of this study was to confirm this anomaly and investigate its possible cause by studying the median and ulnar nerves.Recordings from 50 subjects with normal electrodiagnostic studies were reviewed. The conduction velocity (CV) was measured using different points on the negative phase of the CMAP including its peak and baseline crossing. Collision studies were performed in three healthy subjects to measure the dispersion when nerve action potentials (APs) propagated from elbow to wrist.CV was relatively unaffected by the measurement point on the CMAP. The CMAP duration with elbow stimulation increased minimally compared to wrist stimulation. This was inconsistent with the dispersion of the AP from wrist to elbow measured in collision studies.The insignificant change in the CMAP in spite of axon AP dispersion is an enigma. We hypothesize that the terminal conduction time (TCT) (i.e., conduction in terminal axon branches, neuromuscular transmission, etc.) is independent of axon CV, represents a significant portion of the latency, masks AP dispersion, and reduces CMAP dispersion. This yields similar CMAPs with distal and proximal stimulation. The onset latency at the distal stimulation site does not depend on CV. Thus, onset latency and CV may not reflect the conduction properties of the fastest conducting axons. [ABSTRACT FROM AUTHOR]

In this article, I present three main points that could benefit the "vocal learning and rhythmic synchronization hypothesis", encompassing neurogenetic mechanisms of gene expression transmission and single motor neuron function, classification of different behavioral motor phenotypes (e.g., spontaneous vs. voluntary), and other evolutionary considerations (i.e., the involvement of reward mechanisms). [ABSTRACT FROM AUTHOR]

Neural conditioning to scenarios of muscle disuse is undoubtedly a cause of functional decrements that typically exceed losses of muscle size. Yet establishing the relative contribution of neural adaptation and the specific location in the motor pathway remains technically challenging. Several studies of healthy humans have targeted this system and have established that motor unit firing rate is suppressed following disuse, with a number of critical caveats. It is suppressed in the immobilized limb only, at relative and absolute force levels, and preferentially targets lower‐threshold motor units. Concomitantly, electrophysiological investigation of neuromuscular junction transmission (NMJ) stability of lower‐threshold motor units reveals minimal change following disuse. These findings contrast with numerous other methods, which show clear involvement of the NMJ but are unable to characterize the motor unit to which they belong. It is physiologically plausible that decrements observed following disuse are a result of suppressed firing rate of lower‐threshold motor units and impairment of transmission of the NMJ of higher‐threshold motor units. As such, motor units within the pool should be viewed in light of their varying susceptibility to disuse. [ABSTRACT FROM AUTHOR]

Congenital myasthenic syndromes (CMS) are clinically and genetically heterogeneous diseases caused by mutations affecting neuromuscular transmission. Even if the first symptoms mainly occur during childhood, adult neurologists must confront this challenging diagnosis and manage these patients throughout their adulthood. However, long-term follow-up data from large cohorts of CMS patients are lacking, and the long-term prognosis of these patients is largely unknown. We report the clinical features, diagnostic difficulties, and long-term prognosis of a French nationwide cohort of 235 adult patients with genetically confirmed CMS followed in 23 specialized neuromuscular centres. Data were retrospectively analysed. Of the 235 patients, 123 were female (52.3%). The diagnosis was made in adulthood in 139 patients, 110 of whom presented their first symptoms before the age of 18. Mean follow-up time between first symptoms and last visit was 34 years [standard deviation (SD) = 15.1]. Pathogenic variants were found in 19 disease-related genes. CHRNE -low expressor variants were the most common (23.8%), followed by variants in DOK7 (18.7%) and RAPSN (14%). Genotypes were clustered into four groups according to the initial presentation: ocular group (CHRNE -LE, CHRND , FCCMS), distal group (SCCMS), limb-girdle group (RAPSN , COLQ , DOK7 , GMPPB , GFPT1), and a variable-phenotype group (MUSK , AGRN). The phenotypical features of CMS did not change throughout life. Only four genotypes had a proportion of patients requiring intensive care unit admission that exceeded 20%: RAPSN (54.8%), MUSK (50%), DOK7 (38.6%) and AGRN (25.0%). In RAPSN and MUSK patients most ICU admissions occurred before age 18 years and in DOK7 and AGRN patients at or after 18 years of age. Different patterns of disease course (stability, improvement and progressive worsening) may succeed one another in the same patient throughout life, particularly in AGRN, DOK7 and COLQ. At the last visit, 55% of SCCMS and 36.3% of DOK7 patients required ventilation; 36.3% of DOK7 patients, 25% of GMPPB patients and 20% of GFPT1 patients were wheelchair-bound; most of the patients who were both wheelchair-bound and ventilated were DOK7 patients. Six patients died in this cohort. The positive impact of therapy was striking, even in severely affected patients. In conclusion, even if motor and/or respiratory deterioration could occur in patients with initially moderate disease, particularly in DOK7 , SCCMS and GFPT1 patients, the long-term prognosis for most CMS patients was favourable, with neither ventilation nor wheelchair needed at last visit. CHRNE -LE patients did not worsen during adulthood and RAPSN patients, often severely affected in early childhood, subsequently improved. [ABSTRACT FROM AUTHOR]

Neuromuscular junction disorders lead to secession of bioelectrical activity transmission between motor nerve endings and muscle fibers. In diseases that are severe enough, impulse blockings are observed. This study aims to reveal the behavior of neuromuscular junction before and after impulse blockings. Fourteen recordings harboring impulse blockings from nine myasthenia gravis (MG) patients were included. Recordings were made from frontalis muscle by using concentric needle electrode during voluntary contraction. One hundred traces were acquired in each session. In addition to well-known jitter parameters, new parameters were calculated such as number of consecutive impulse blocking groups, number of impulse blockings in each group, ratio of maximum number of consecutive impulse blockings to all number of blockings. Graphics were composed to show location change behavior of jittering potential in all traces. For jittering potential, before or after a single impulse blocking the amount of getting further away from trigger peak was greater than getting closer to trigger peak. However, after consecutive impulse blockings the amount of getting closer to trigger peak was greater than the amount of getting further away. The behavior of neuromuscular junction before and after impulse blockings was demonstrated in MG patients. Moreover, new features were extracted for jitter studies. Building models for different diseases according to their impulse blockings may be possible with the developed algorithm. [ABSTRACT FROM AUTHOR]

The neuromuscular junction (NMJ) is the site where the motor neuron innervates skeletal muscle, enabling muscular contraction. Congenital myasthenic syndromes (CMS) arise when mutations in any of the approximately 35 known causative genes cause impaired neuromuscular transmission at the NMJ, resulting in fatigable muscle weakness. A subset of five of these CMS-causative genes are associated with protein glycosylation. Glutamine-fructose-6-phosphate transaminase 1 (Gfpt1) is the rate-limiting enzyme within the hexosamine biosynthetic pathway (HBP), a metabolic pathway that produces the precursors for glycosylation. We hypothesized that deficiency in Gfpt1 expression results in aberrant or reduced glycosylation, impairing the proper assembly and stability of key NMJ-associated proteins. Using both in vitro and in vivo Gfpt1-deficient models, we determined that the acetylcholine receptor delta subunit (AChRδ) has reduced expression and is hypo-glycosylated. Using laser capture microdissection, NMJs were harvested from Gfpt1 knockout mouse muscle. A lower-molecular-weight species of AChRδ was identified at the NMJ that was not detected in controls. Furthermore, Gfpt1-deficient muscle lysates showed impairment in protein O-GlcNAcylation and sialylation, suggesting that multiple glycan chains are impacted. Other key NMJ-associated proteins, in addition to AChRδ, may also be differentially glycosylated in Gfpt1-deficient muscle. [ABSTRACT FROM AUTHOR]

Botulinum toxin A (BT-A), a potential neurotoxin produced by the bacterium Clostridium botulinum, is known for its ability to prevent the release of acetylcholine at the neuromuscular synapse, leading to temporary muscle paralysis. BT-A is used for a wide range of therapeutic applications. Several studies have shown mechanisms beyond the inhibition of acetylcholine release for pain control. BT-A inhibits the release of neurotransmitters associated with pain and inflammation, such as glutamate, CGRP, and substance P. Additionally, it would be effective in nerve entrapment leading to neuronal hypersensitivity, which is known as a new pathogenesis of painful conditions. BT-A has been applied to the treatment of a wide variety of neurological disorders. Since 2010, BT-A application has been approved and widely used as a chronic migraine prophylaxis. Moreover, due to its effects on pain through sensory modulation, it may also be effective for other headaches. Several studies using BT-A, at different doses and administration sites for headaches, have shown beneficial effects on frequency and severity. In this review, we provide an overview of using BT-A to treat primary and secondary headache disorders. [ABSTRACT FROM AUTHOR]

Background: Neuromuscular blocking agents (NMBAs) are a crucial component of anesthesia and intensive care through the relaxation of skeletal muscles. They can lead to adverse reactions such as postoperative residual neuromuscular block. Only one agent is capable of an instant block reversal in deep block situations, but is restricted to aminosteroid agents. Among animal models, non‐human primates are an essential model for a great diversity of human disease models. The main objective of this study was to establish a model for NMBA monitoring with current available drugs before testing new reversal agents. Methods: Seven healthy male cynomolgus macaques were randomly assigned to this study. Experiments using macaques were approved by the local ethical committee (CEtEA #44). All animals were anesthetized according to institutional guidelines, with ketamine and medetomidine, allowing IV line placement and tracheal intubation. Anesthesia was maintained with isoflurane. Either rocuronium bromine (with or without sugammadex reversal) or atracurium besylate was evaluated. Monitoring was performed with two devices, TOF‐Watch and ToFscan, measuring the T4/T1 and the T4/Tref ratios, respectively. Nonparametric Mann–Whitney statistical analyses were done when indicated. Results: NMBA monitoring required adaptation compared to humans, such as stimulus intensity and electrode placement, to be efficient and valid in cynomolgus macaques. When administered, both NMBAs induced deep and persistent neuro‐muscular block at equivalent doses to clinical doses in humans. The rocuronium‐induced profound neuromuscular block could be reversed using the cyclodextrin sugammadex as a reversal agent. We report no adverse effects in these models by clinical observation, blood chemistry, or complete blood count. Conclusion: These results support the use of non‐human primate models for neuromuscular block monitoring. This represented the first step before the forthcoming testing of new NMBA‐reversal agents. [ABSTRACT FROM AUTHOR]

• More than 90 % of both patient groups, oMG and gMG were antibody-positive. • AChR antibody titer above 100 nmol/L seems to predict generalization. • oMG patients responded better to treatment, achieving quicker symptom satisfaction. • 1/3 (350) of all MG patients in Denmark was included in this chart review. • No difference in thymus pathology was found between oMG and gMG patients. The aim of this study was to evaluate clinical and serological differences between the ocular myasthenia gravis (oMG) and generalized MG (gMG). This study is a retrospective chart review, in which data was collected from patients fulfilling 2 of 3 diagnostic MG criteria (positive antibodies, evidence of neuromuscular transmission defect on neurophysiological examination, positive effect of pyridostigmine treatment). 350 patients were included and data concerning demographics and MG medical history were collected. Patients with oMG accounted for 15.7 % of the included patients. The two subgroups differed significantly in oMG having a later age at onset, lower AChR antibody-titers, longer doctor-to-diagnosis delay and less intensive MG treatment. Additionally, patients with oMG were faster at reaching a well-controlled disease state. Thymus pathology, number of antibody-positive (95.9 % of gMG and 94.5 % of oMG), sex, number of other autoimmune diseases and delay before drug stability did not differ between oMG and gMG. In conclusion, oMG is presumably a milder form of gMG characterized by lower AChR antibody-titers, a milder phenotype, and a quicker response to a less aggressive treatment. But otherwise, oMG and gMG show very similar characteristics, including the same frequency of positive AChR antibodies, which seems new compared to previous reports. [ABSTRACT FROM AUTHOR]

For animals to meet environmental challenges, the activity patterns of specialized oscillatory neural circuits, central pattern generators (CPGs), controlling rhythmic movements like breathing and locomotion, are adjusted by neuromodulation. As a representative example, the leech heartbeat is controlled by a CPG driven by two pairs of mutually inhibitory interneurons, heart interneuron (HN) half-center oscillators (HCO). Experiments and modeling indicate that neuromodulation of HCO navigates this CPG between dysfunctional regimes by employing a co-regulating inverted relation; reducing Na+/K+ pump current and increasing hyperpolarization-activated (h-) current. Simply reducing pump activity or increasing h-current leads to either seizure-like bursting or an asymmetric bursting dysfunctional regime, respectively. Here, we demonstrate through modeling that, alongside this coregulation path, a new bursting regime emerges. Both regimes fulfill the criteria for functional bursting activity. Although the cycle periods and burst durations of these patterns are roughly the same, the new one exhibits an intra-burst spike frequency that is twice as high as the other. This finding suggests that neuromodulation could introduce additional functional regimes with higher spike frequency, and thus more effective synaptic transmission to motor neurons. We found that this new regime co-exists with the original bursting. The HCO can be switched between them by a short pulse of excitatory or inhibitory conductance. In this domain of coexisting functional patterns, an isolated cell model exhibits only one regime, a severely dysfunctional plateau-containing, seizure-like activity. This aligns with widely reported notion that deficiency of inhibition can cause seizures and other dysfunctional neural activities. We show that along the coregulation path of neuromodulation, the high excitability of the single HNs induced by myomodulin is harnessed by mutually inhibitory synaptic interactions of the HCO into the functional bursting pattern. [ABSTRACT FROM AUTHOR]

Background Methods Results Conclusions Inhibitory neuromuscular transmission in the gastrointestinal tract is mediated by intrinsic nitrergic and purinergic neurons. Purines activate G protein‐coupled receptor P2Y1 receptors, increasing intracellular Ca2+ that activates small conductance calcium‐activated potassium (SKCa) channels. Little is known about the effect of adrenergic receptor activation on intestinal smooth muscle. In vascular tissue, stimulation of α‐adrenoceptors causes smooth muscle contraction, while their effect on intestinal tissue is poorly understood. This study aimed to pharmacologically characterize the effect of α‐adrenoceptor activation in the rat colon, which shares similar inhibitory pathways to the human colon.Muscle bath experiments were performed with the rat proximal, mid, and distal colon oriented both circularly and longitudinally.The α1‐adrenoceptor agonist phenylephrine (PE) (10−8–10−5 M) evoked concentration‐dependent relaxations of the intestinal smooth muscle from all regions and orientations. However, in the mid‐circular colon at low PE concentrations, a contraction sensitive to 10−5 M phentolamine (non‐selective α‐adrenoceptor blocker), the neural blocker tetrodotoxin (TTX; 10−6 M), and atropine (10−6 M) was recorded. PE‐induced relaxations were insensitive to TTX (10−6 M) and the nonselective β‐adrenoceptor blocker propranolol (10−6 M). In contrast, PE‐induced relaxations were blocked by phentolamine (10−5 M), prazosin (10−6 M) (α1‐adrenoceptor blocker), and RS17053 (10−6 M) (α1A‐blocker), but not by yohimbine (10−6 M) (α2‐adrenoceptor blocker). Apamin (10−6 M), a SKCa channel blocker, abolished PE‐induced relaxations.Contractile responses in the circular muscle of the mid colon could be attributed to α‐adrenoceptors located on enteric cholinergic neurons. Stimulation of α1A‐adrenoreceptors activates SKCa channels to cause smooth muscle relaxation, which constitutes a signaling pathway that shares similarities with P2Y1 receptors. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is an antibody-mediated autoimmune disorder characterized by altered neuromuscular transmission, which causes weakness and fatigability in the skeletal muscles. The etiology of MG is complex, being associated with multiple genetic and environmental factors. Over recent years, progress has been made in understanding the immunological alterations implicated in the disease, but the exact pathogenesis still needs to be elucidated. A pathogenic interplay between innate immunity and autoimmunity contributes to the intra-thymic MG development. Epigenetic changes are critically involved in both innate and adaptive immune response regulation. They can act as (i) pathological factors besides genetic predisposition and (ii) co-factors contributing to disease phenotypes or patient-specific disease course/outcomes. This article reviews the role of non-coding RNAs (ncRNAs) as epigenetic factors implicated in MG. Particular attention is dedicated to microRNAs (miRNAs), whose expression is altered in MG patients' thymuses and circulating blood. The long ncRNA (lncRNA) contribution to MG, although not fully characterized yet, is also discussed. By summarizing the most recent and fast-growing findings on ncRNAs in MG, we highlight the therapeutic potential of these molecules for achieving immune regulation and their value as biomarkers for the development of personalized medicine approaches to improve disease care. [ABSTRACT FROM AUTHOR]

The initiation of the fast synchronous quantal release of neurotransmitters in central and peripheral synapses is ensured by a local increase in the concentration of Ca2+ ions in the nerve terminals near the Ca2+ sensors of synaptic vesicles in response to depolarization of the presynaptic membrane by an action potential (AP) propagating along the axon. Ca2+ entry into the nerve terminal through presynaptic voltage-dependent Ca2+ channels CaV2.1 or CaV2.2 (P/Q- or N-type) is the main route to form a dynamic Ca2+ signal that triggers the process of exocytosis of synaptic vesicles in virtually all types of chemical synapses and is able to induce the development of certain Ca2+-dependent forms of synaptic plasticity. However, in recent years it has become obvious that the set of sources and the spectrum of presynaptic Ca2+ signals are very diverse. Identification of the ensemble of regulatory Ca2+ entries co-operating with their targets, as well as characterization of their contribution to the mechanisms controlling quantal neurotransmitter release, is a topical area of modern synaptic physiology. Among the Ca2+ entries additional to those involved in triggering vesicular endocytosis, L-type Ca2+ channels are of particular interest. Their function and activation conditions in neuromuscular junctions (NMJs) are poorly studied, providing no unambiguous idea of the role of this Ca2+ entry in the regulation of acetylcholine (ACh) release in vertebrate motor synapses. This review systematizes the currently available data on the diverse functional role of voltage-gated Ca2+ channels in mammalian NMJs and presynaptic signaling pathways that control these Ca2+-inputs and their implication in the processes of fine-tuning ACh quantal release. [ABSTRACT FROM AUTHOR]

Background We previously reported that normalization of motor evoked potential (MEP) monitoring amplitude by compound muscle action potential (CMAP) after peripheral nerve stimulation prevented the expression of anesthetic fade (AF), suggesting that AF might be due to reduced synaptic transfer in the neuromuscular junction. Methods We calculated the time at which AF began for each of craniotomy and spinal cord surgery, and examined whether AF was avoided by CMAP after peripheral nerve stimulation normalization in each. Similar studies were also made with respect to the upper and lower limb muscles. Results AF was observed in surgery lasting 160 minutes for craniotomy and 260 minutes or more for spinal surgery, and 195 minutes in the upper limb muscles and 135 minutes in the lower limb muscles. In all the series, AF could be avoided by CMAP after peripheral nerve stimulation normalization. Conclusion AF of MEP occurred in both craniotomy and spinal cord surgery, and it was also corrected by CMAP after peripheral nerve stimulation. AF is considered to be mainly due to a decrease in synaptic transfer of the neuromuscular junction due to the accumulation of propofol because of the avoidance by CMAP normalization. However, it may be partially due to a decrease in the excitability of pyramidal tracts and α-motor neurons, because AF occurred earlier in the lower limb muscles than in the upper limb muscles. [ABSTRACT FROM AUTHOR]

Congenital 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. Data were gathered retrospectively from the medical charts. Only likely pathogenic and pathogenic variants were included in the analysis. We 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. This 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. [ABSTRACT FROM AUTHOR]

Background: Congenital Myasthenic Syndromes (CMS) are rare genetic diseases, which share as a common denominator muscle fatigability due to failure of neuromuscular transmission. A distinctive clinical feature of presynaptic CMS variants caused by defects of the synthesis of acetylcholine is the association with life-threatening episodes of apnea. One of these variants is caused by mutations in the SLC5A7 gene, which encodes the sodium-dependent HC-3 high-affinity choline transporter 1 (CHT1). To our knowledge there are no published cases of this CMS type in Latin America. Case presentation: We present two cases of CHT1-CMS. Both patients were males presenting with repeated episodes of apnea, hypotonia, weakness, ptosis, mild ophthalmoparesis, and bulbar deficit. The first case also presented one isolated seizure, while the second case showed global developmental delay. Both cases, exhibited incomplete improvement with treatment with pyridostigmine. Conclusions: This report emphasizes the broad incidence of CMS with episodic apnea caused by mutations in the SLC5A7 gene and the frequent association of this condition with serious manifestations of central nervous system involvement. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: High-resolution manometry (HRM) can quantify swallowing pathophysiology to evaluate the status of the pharynx. Sequential 4-channel neuromuscular electrical stimulation (NMES) was recently developed based on the normal contractile sequences of swallowing-related muscles. This study aimed to examine the effects of sequential 4-channel NMES for compensatory application during swallowing and to observe the residual effects after the application of NMES using HRM. Results: Sequential 4-channel NMES significantly improved the HRM parameters, with respect to the maximal pressure and area of the velopharynx (VP), maximal pressure and area of the mesopharynx (MP), and upper esophageal sphincter (UES) activation and nadir duration. Furthermore, the improvement in the pressure and area variables of the VP and MP showed a tendency to maintain even when measured after NMES, but there are no significant differences. Conclusions: The present study suggests that the sequential 4-channel NMES application of the suprahyoid and infrahyoid muscles during swallowing improves the pressure, area, and time variables of the oropharynx, as measured by HRM, and it is likely that the effects may persist even after stimulation. Trial Registration Clinicaltrials.gov, registration number: NCT02718963 (initial release: 03/20/2016, actual study completion date: 06/24/2016, last release: 10/20/2020). [ABSTRACT FROM AUTHOR]

The INSPIRE randomized clinical trial demonstrated that a high protein diet (HPRO) combined with neuromuscular electrical stimulation (NMES) attenuates muscle atrophy and may improve outcomes after aneurysmal subarachnoid hemorrhage We sought to identify specific metabolites mediating these effects. Blood samples were collected from subjects on admission prior to randomization to either standard of care (SOC; N = 12) or HPRO + NMES (N = 12) and at 7 days. Untargeted metabolomics were performed for each plasma sample. Sparse partial least squared discriminant analysis identified metabolites differentiating each group. Correlation coefficients were calculated between each metabolite and total protein per day and muscle volume. Multivariable models determined associations between metabolites and muscle volume. Unique metabolites (18) were identified differentiating SOC from HPRO + NMES. Of these, 9 had significant positive correlations with protein intake. In multivariable models, N-acetylleucine was significantly associated with preserved temporalis [OR 1.08 (95% CI 1.01, 1.16)] and quadricep [OR 1.08 (95% CI 1.02, 1.15)] muscle volume. Quinolinate was also significantly associated with preserved temporalis [OR 1.05 (95% CI 1.01, 1.09)] and quadricep [OR 1.04 (95% CI 1.00, 1.07)] muscle volume. N-acetylserine and β-hydroxyisovaleroylcarnitine were associated with preserved temporalis or quadricep volume. Metabolites defining HPRO + NMES had strong correlations with protein intake and were associated with preserved muscle volume. [ABSTRACT FROM AUTHOR]

Purpose: Spinal muscular atrophy (SMA) is a rare, autosomal-recessive disease characterized by progressive muscular atrophy and weakness resulting in substantial disability and short life expectancy. The objective of this cross-sectional study was to assess health-related quality of life (HRQoL) of adults with SMA in Germany in the era of disease-modifying therapy. Methods: Adults with SMA were recruited via the German national TREAT-NMD SMA patient registry. HRQoL was measured using the EQ-5D-5L, the Health Utilities Index Mark III (HUI), and the Short Form (36) Health Survey (SF-36). Estimates were stratified by current best motor function of the lower limb and trunk (i.e., non-sitter, sitter, and walker) and SMA type (i.e., type I, II, and III). Results: A total of 82 adults with SMA (mean age: 42 years, 51% female) self-completed the study questionnaire. The mean EQ-5D-5L utility was estimated at 0.5135 (range across subgroups: 0.31–0.99), mean EQ-VAS at 69.71 (64.67–90.00), mean HUI-derived utility at 0.3171 (– 0.02–0.96), mean SF-6D utility at 0.6308 (0.58–0.65), and mean SF-36 Physical Component Summary and Mental Health Component Summary scores at 33.78 (9.92–53.10) and 53.49 (21.02–72.25), respectively. Conclusions: We show that adults with SMA experience considerable impairment across a wide range of health dimensions, including mobility, dexterity, pain, and emotional well-being. However, our results exhibit non-trivial variability across clinical subgroups and HRQoL measures. These data contribute to our understanding of the subjective impact of living with a severely debilitating neuromuscular disease, such as SMA. [ABSTRACT FROM AUTHOR]

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A 76‐year‐old man with spinal and bulbar muscular atrophy (SBMA) developed an acute course of the dropped head with diurnal fluctuations that worsened in the evening. He was diagnosed with myasthenic syndrome based on a decreased response to repeated stimulation, as well as increased jitter and blocking on single‐fiber electromyography, indicating disturbed neuromuscular transmission. Dropped head symptom was successfully alleviated and maintained by immunotherapy. Although limited reports are available on SBMA cases accompanied by myasthenic syndrome and on the clinical impact of impaired neuromuscular transmission on SBMA, myasthenic syndrome may be a common condition and even a part of the phenotypic spectrum of SBMA. To our knowledge, this is the first case of SBMA comorbid with myasthenic syndrome limited to the dropped head. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• We report a recurrent intronic homozygous c.1023+5G> A desmin mutation in indian patients. • Second report of recessive desminopathy associated with mixed limb girdle CMS – myofibrillar myopathy. • Partial loss of desmin leading to NMJ dysfunction and CMS phenotype. • Leaky splice site with intron retention leads to partial desmin loss. Recessive desminopathies are rare and often present as severe early-onset myopathy. Here we report a milder phenotype in three unrelated patients from southern India (2 M, 1F) aged 16, 21, and 22 years, who presented with childhood-onset, gradually progressive, fatigable limb-girdle weakness, ptosis, speech and swallowing difficulties, without cardiac involvement. Serum creatine kinase was elevated, and repetitive nerve stimulation showed decrement in all. Clinical improvement was noted with pyridostigmine and salbutamol in two patients. All three patients had a homozygous substitution in intron 5: DES(NM_001927.4):c.1023+5G> A , predicted to cause a donor splice site defect. Muscle biopsy with ultrastructural analysis suggested myopathy with myofibrillar disarray, and immunohistochemistry showed partial loss of desmin with some residual staining, while western blot analysis showed reduced desmin. RT-PCR of patient muscle RNA revealed two transcripts: a reduced normal desmin transcript and a larger abnormal transcript suggesting leaky splicing at the intron 5 donor site. Sequencing of the PCR products confirmed the inclusion of intron 5 in the longer transcript, predicted to cause a premature stop codon. Thus, we provide evidence for a leaky splice site causing partial loss of desmin associated with a unique phenotypic presentation of a milder form of desmin-related recessive myopathy overlapping with congenital myasthenic syndrome. [ABSTRACT FROM AUTHOR]

Objective: The effect of vertebral osteoporosis on disc degeneration remains controversial. The aim of this study was to conduct a systematic review and meta-analysis of relevant animal studies to shed more light on the effects and mechanisms of vertebral osteoporosis on disc degeneration and to promote the resolution of the controversy. Methods: The PubMed, Cochrane Library, and Embase databases were searched for studies that met the inclusion criteria. Basic information and data were extracted from the included studies and data were analyzed using STATA 15.1 software. This study was registered on INPLASY with the registration number INPLASY202370099 and https://doi.org/10.37766/inplasy2023.7.0099. Results: A total of 13 studies were included in our study. Both animals, rats and mice, were covered. Meta-analysis results showed in disc height index (DHI) (P < 0.001), histological score (P < 0.001), number of osteoblasts in the endplate (P = 0.043), number of osteoclasts in the endplate (P < 0.001), type I collagen (P < 0.001), type II collagen (P < 0.001), aggrecan (P < 0.001), recombinant a disintegrin and metalloproteinase with thrombospondin-4 (ADAMTS-4) (P < 0.001), matrix metalloproteinase-1 (MMP-1) (P < 0.001), MMP-3 (P < 0.001), MMP-13 (P < 0.001), the difference between the osteoporosis group and the control group was statistically significant. In terms of disc volume, the difference between the osteoporosis group and the control group was not statistically significant (P = 0.459). Conclusion: Our study shows that vertebral osteoporosis may exacerbate disc degeneration. Abnormal bone remodeling caused by vertebral osteoporosis disrupts the structural integrity of the endplate, leading to impaired nutrient supply to the disc, increased expression of catabolic factors, and decreased levels of type II collagen and aggrecan may be one of the potential mechanisms. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to evaluate the implementation of NGS within the French mitochondrial network, MitoDiag, from targeted gene panels to whole exome sequencing (WES) or whole genome sequencing (WGS) focusing on mitochondrial nuclear‐encoded genes. Methods: Over 2000 patients suspected of Primary Mitochondrial Diseases (PMD) were sequenced by either targeted gene panels, WES or WGS within MitoDiag. We described the clinical, biochemical, and molecular data of 397 genetically confirmed patients, comprising 294 children and 103 adults, carrying pathogenic or likely pathogenic variants in nuclear‐encoded genes. Results: The cohort exhibited a large genetic heterogeneity, with the identification of 172 distinct genes and 253 novel variants. Among children, a notable prevalence of pathogenic variants in genes associated with oxidative phosphorylation (OXPHOS) functions and mitochondrial translation was observed. In adults, pathogenic variants were primarily identified in genes linked to mtDNA maintenance. Additionally, a substantial proportion of patients (54% (42/78) and 48% (13/27) in children and adults, respectively), undergoing WES or WGS testing displayed PMD mimics, representing pathologies that clinically resemble mitochondrial diseases. Interpretation: We reported the largest French cohort of patients suspected of PMD with pathogenic variants in nuclear genes. We have emphasized the clinical complexity of PMD and the challenges associated with recognizing and distinguishing them from other pathologies, particularly neuromuscular disorders. We confirmed that WES/WGS, instead of panel approach, was more valuable to identify the genetic basis in patients with "possible" PMD and we provided a genetic testing flowchart to guide physicians in their diagnostic strategy. [ABSTRACT FROM AUTHOR]

Organophosphate pesticide poisoning challenges health care systems worldwide. Furthermore, nerve agents remain a continuous threat. The treatment options for organophosphate poisoning have virtually been unchanged for decades, relying on symptomatic treatment and the use of oximes to indirectly restore neuromuscular function. Hence, compounds targeting directly nicotinic acetylcholine receptors (nAChRs) might substantially improve treatment options. The current study investigated a series of bispyridinium analogues with a trimethylene or 2,2′-diethyloxy linker in a rat hemidiaphragm model, using indirect field stimulation. Methyl- and ethyl-substituted bispyridinium analogues restored neuromuscular function up to 37 ± 17% (MB419, a 3-methyl analogue) at a stimulation frequency of 20 Hz. The bispyridinium analogues with a 2- or 3-methyl group, or a 2- or 3-ethyl group, tended towards a higher restoration of neuromuscular function than those with a 4-methyl or 4-ethyl group, respectively. The current data can be used for future studies to optimize structure-based molecular modeling of compounds targeting the nAChR. [Display omitted] • Bispyridinium non-oximes analogues with a trimethylene or 2,2′-diethyloxy linker and various substituents were studied. • Methyl- and ethyl- substituted compounds with a trimethylene linker were able to partially restore muscle force. • The investigated bispyridinium analogues can be used for future studies to optimize structure-based molecular modeling. [ABSTRACT FROM AUTHOR]

Loss-of-function mutations in MEGF10 lead to a rare and understudied neuromuscular disorder known as MEGF10-related myopathy. There are no treatments for the progressive respiratory distress, motor impairment, and structural abnormalities in muscles caused by the loss of MEGF10 function. In this study, we deployed cellular and molecular assays to obtain additional insights about MEGF10-related myopathy in juvenile, young adult, and middle-aged Megf10 knockout (KO) mice. We found fewer muscle fibers in juvenile and adult Megf10 KO mice, supporting published studies that MEGF10 regulates myogenesis by affecting satellite cell differentiation. Interestingly, muscle fibers do not exhibit morphological hallmarks of atrophy in either young adult or middle-aged Megf10 KO mice. We next examined the neuromuscular junction (NMJ), in which MEGF10 has been shown to concentrate postnatally, using light and electron microscopy. We found early and progressive degenerative features at the NMJs of Megf10 KO mice that include increased postsynaptic fragmentation and presynaptic regions not apposed by postsynaptic nicotinic acetylcholine receptors. We also found perisynaptic Schwann cells intruding into the NMJ synaptic cleft. These findings strongly suggest that the NMJ is a site of postnatal pathology in MEGF10-related myopathy. In support of these cellular observations, RNA-seq analysis revealed genes and pathways associated with myogenesis, skeletal muscle health, and NMJ stability dysregulated in Megf10 KO mice compared to wild-type mice. Altogether, these data provide new and valuable cellular and molecular insights into MEGF10-related myopathy. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is a rare chronic autoimmune disease caused by the production of autoantibodies against the postsynaptic membrane receptors present at the neuromuscular junction. This condition is characterized by fatigue and muscle weakness, including diplopia, ptosis, and systemic impairment. Emerging evidence suggests that in addition to immune dysregulation, the pathogenesis of MG may involve mitochondrial damage and ferroptosis. Mitochondria are the primary site of energy production, and the reactive oxygen species (ROS) generated due to mitochondrial dysfunction can induce ferroptosis. Nanomedicines have been extensively employed to treat various disorders due to their modifiability and good biocompatibility, but their application in MG management has been rather limited. Nevertheless, nanodrug delivery systems that carry immunomodulatory agents, anti-oxidants, or ferroptosis inhibitors could be effective for the treatment of MG. Therefore, this review focuses on various nanoplatforms aimed at attenuating immune dysregulation, restoring mitochondrial function, and inhibiting ferroptosis that could potentially serve as promising agents for targeted MG therapy. [ABSTRACT FROM AUTHOR]

Purpose: Vertebral endplate lesions (EPLs) caused by severe disk degeneration are associated with low back pain. However, its pathophysiology remains unclear. In this study, we aimed to develop a vertebral EPL rat model mimicking severe intervertebral disk (IVD) degeneration by injecting monosodium iodoacetate (MIA) into the IVDs and evaluating it by assessing pain-related behavior, micro-computed tomography (CT) findings, and histological changes. Methods: MIA was injected into the L4-5 and L5-6 IVDs of Sprague–Dawley rats. Their behavior was examined by measuring the total distance traveled and the total number of rearing in an open square arena. Bone alterations and volume around the vertebral endplate were assessed using micro-CT. Safranin-O staining, immunohistochemistry, and tartrate-resistant acid phosphatase (TRAP) staining were performed for histological assessment. Results: The total distance and number of rearing times in the open field were significantly reduced in a time-dependent manner. Micro-CT revealed intervertebral osteophytes and irregularities in the endplates at 12 weeks. The bone volume/tissue volume (BV/TV) around the endplates significantly increased from 6 weeks onward. Safranin-O staining revealed severe degeneration of IVDs and endplate disorders in a dose- and time-dependent manner. Calcitonin gene-related peptide-positive nerve fibers significantly increased from 6 weeks onward. However, the number of osteoclasts decreased over time. Conclusion: Our rat EPL model showed progressive morphological vertebral endplate changes in a time- and concentration-dependent manner, similar to the degenerative changes in human IVDs. This model can be used as an animal model of severe IVD degeneration to better understand the pathophysiology of EPL. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that the levels of IgG against neurotransmitter receptors are increased in patients with schizophrenia. Genome-wide association (GWA) studies of schizophrenia confirmed that 108 loci harbouring over 300 genes were associated with schizophrenia. Although the functional implications of genetic variants are unclear, theoretical functional alterations of these genes could be replicated by the presence of autoantibodies. This study examined the levels of plasma IgG antibodies against four neurotransmitter receptors, CHRM4, GRM3, CHRNA4 and CHRNA5, using an in-house ELISA in 247 patients with schizophrenia and 344 non-psychiatric controls. Four peptides were designed based on in silico analysis with computational prediction of HLA-DRB1 restricted and B-cell epitopes. The relationship between plasma IgG levels and psychiatric symptoms, as defined by the Operational Criteria Checklist for Psychotic Illness and Affective Illness (OPCRIT), were examined. The results showed that the levels of plasma IgG against peptides derived from CHRM4 and CHRNA4 were significantly increased in patients with schizophrenia compared with control subjects, but there was no significant association of plasma IgG levels with any symptom domain or any specific symptoms. These preliminary results suggest that CHRM4 and CHRNA4 may be novel targets for autoantibody responses in schizophrenia, although the pathogenic relationship between increased serum autoantibody levels and schizophrenia symptoms remains unclear. [ABSTRACT FROM AUTHOR]

Anti‐acetylcholine receptor antibody (AChRAb) targets nicotinic acetylcholine receptors (AChRs) of the neuromuscular junction (NMJ). AChRAb induces degradation of AChRs, which causes a decrease in the efficacy of neuromuscular transmission. The clinical condition induced by this process is myasthenia gravis (MG). Transmission failure at the NMJ is detectable by a repetitive nerve stimulation test. AChRAb may be complicated with thymic abnormalities (thymoma and/or lymphoreticular hyperplasia [LFH]). Moreover, autoimmune thyroid disease may accompany MG. Thymoma and LFH have etiological roles in AChRAb production, and the removal of thymoma and LFH improve MG symptoms. MG therapies, such as acetylcholine esterase inhibitor (AChEI), aim to increase the efficacy of NMJ transmission; however, the effect of AChEI is limited. The primary therapy aims to decrease AChRAb and is combined with thymectomy. There are two methods to remove AChRAb from the patients' blood: (1) reduce the production of immunoglobulins by administration of corticosteroid and/or immunosuppressants and (2) remove immunoglobulin by blood purification. In some patients, long‐lasting immunosuppression is necessary, which causes adverse events. Combinatory use of other immunosuppressants reduces the adverse events of corticosteroids. In addition, intravenous immunoglobulin is available to modify the proportion of immunoglobulin in patients' blood. Recently, humanized monoclonal antibodies against specific molecules have been introduced for immunoglobulin modification; however, they are not AChRAb specific. Thus, it is necessary to consider the safety and cost‐effectiveness of therapies. [ABSTRACT FROM AUTHOR]

Objective: Obstructive sleep apnea (OSA) is a sleep disorder accompanied by intermittent hypoxia. Neuromuscular transmission (NT) is known to be disturbed under chronic hypoxia. In this descriptive study, it has been aimed to test NT under intermittent hypoxia in OSA. Methods: Thirty-nine newly diagnosed OSA patients without any comorbidities or conditions that alter NT were included in the study. Jitter analysis was performed using a concentric needle electrode. Results: The mean jitter value of 39 OSA patients was 25.9 ± 3.7 μs. When compared to the mean reference jitter values, patients in the present study had significantly higher jitter (p < 0.001). Seven (17.9%) patients met the electrophysiological criteria for NT failure. Conclusion: The authors propose that intermittent hypoxia can be the trigger for NT failure in OSA. The interaction between increased oxidative stress and disturbed mitochondrial functions may also contribute. [ABSTRACT FROM AUTHOR]

Neuromuscular blocking agents are a crucial pharmacological element of general anesthesia. Decades of observations and scientific studies have resulted in the identification of many risks associated with the uncontrolled use of neuromuscular blocking agents during general anesthesia or an incomplete reversal of neuromuscular blockade in the postoperative period. Residual relaxation and acute postoperative respiratory depression are the most serious consequences. Cyclic recommendations have been developed by anesthesiology societies from many European countries as well as from the United States and New Zealand. The newest recommendations from the American Society of Anesthesiologists and the European Society of Anesthesiology were published in 2023. These publications contain very detailed recommendations for monitoring the dosage of skeletal muscle relaxants in the different stages of anesthesia—induction, maintenance and recovery, and the postoperative period. Additionally, there are recommendations for various special situations (for example, rapid sequence induction) and patient populations (for example, those with organ failure, obesity, etc.). The guidelines also refer to pharmacological drugs for reversing the neuromuscular transmission blockade. Despite the development of several editions of recommendations for monitoring neuromuscular blockade, observational and survey data indicate that their practical implementation is very limited. The aim of this review was to present the professional, technical, and technological factors that limit the implementation of these recommendations in order to improve the implementation of the guidelines and increase the quality of anesthesiological procedures and perioperative safety. [ABSTRACT FROM AUTHOR]

• A familial childhood onset, slowly progressive TTN myopathy can be associated with late-onset cardiomyopathy. • Next generation sequencing allows to include TTN in the testing of genetic neuromuscular and cardiac diseases. • Parallel assessment of muscle RNA and protein studies might explain the phenotypic variability among carriers of similar pathogenic TTN variants. This report describes a novel TTN -related phenotype in two brothers, both affected by a childhood onset, very slowly progressive myopathy with cores, associated with dilated cardiomyopathy only in their late disease stages. Clinical exome sequencing documented in both siblings the heterozygous c.2089A>T and c.19426+2T>A variants in TTN. The c.2089A>T, classified in ClinVar as possibly pathogenic, introduces a premature stop codon in exon 14, whereas the c.19426+2T>A affects TTN alternative splicing. The unfeasibility of segregation studies prevented us from establishing the inheritance mode of the muscle disease in this family, although the lack of any reported muscle or heart symptoms in both parents might support an autosomal recessive transmission. In this view, the occurrence of cardiomyopathy in both probands might be related to the c.2089A>T truncating variant in exon 14, and the childhood onset, slowly progressive myopathy to the c.19426+2T>A splicing variant, possibly allowing translation of an almost full length TTN protein. [ABSTRACT FROM AUTHOR]

Aim: Force expression is characterized by an interplay of biological and molecular determinants that are expected to differentiate males and females in terms of maximal performance. These include muscle characteristics (muscle size, fiber type, contractility), neuromuscular regulation (central and peripheral factors of force expression), and individual genetic factors (miRNAs and gene/protein expression). This research aims to comprehensively assess these physiological variables and their role as determinants of maximal force difference between sexes. Methods: Experimental evaluations include neuromuscular components of isometric contraction, intrinsic muscle characteristics (proteins and fiber type), and some biomarkers associated with muscle function (circulating miRNAs and gut microbiome) in 12 young and healthy males and 12 females. Results: Male strength superiority appears to stem primarily from muscle size while muscle fiber‐type distribution plays a crucial role in contractile properties. Moderate‐to‐strong pooled correlations between these muscle parameters were established with specific circulating miRNAs, as well as muscle and plasma proteins. Conclusion: Muscle size is crucial in explaining the differences in maximal voluntary isometric force generation between males and females with similar fiber type distribution. Potential physiological mechanisms are seen from associations between maximal force, skeletal muscle contractile properties, and biological markers. [ABSTRACT FROM AUTHOR]

Background. The idea of a neuromuscular defect in migraine relates to the emergence of mutations in the CACNA1A gene that encodes the subunit of P/Q-type calcium channels in the motor nerve terminals. This study used single-fi bre electromyography (SFEMG) to investigate the potential impact of an underlying channelopathy on subclinical neuromuscular transmission at the motor end plate in different types of migraine. Additionally, we sought to validate previous findings, explore the pathophysiology, and examine any potential relationship between neuromuscular dysfunction and disease severity using the Migraine Disability Assessment Scale (MIDAS) and Visual Analog Scale (VAS). Material and methods. We enrolled 25 healthy volunteers, 30 migraineurs with aura and 30 without aura diagnosed according to the 2018 criteria of the International Headache Society. Voluntary SFEMG was performed on the frontalis muscle. Jitter values were analysed, including the mean individual jitter values of the migraine group, the number of fibers with increased jitter, the mean Mean Consecutive Difference (MCD), and the lowest and highest jitter values, which were then compared with those of the control group. The intensity of the migraine attacks was assessed using the VAS, while disability was evaluated using the MIDAS. Results. Our findings revealed that the highest jitter values in migraine patients were significantly higher than those observed in the control group. Furthermore, we conducted a subgroup analysis within the migraine group and found that individuals with aura had higher average MCD values compared to those without aura and the control group. Additionally, we examined the association between MIDAS and VAS scores with increased jitter values and neuromuscular transmission abnormalities, but no statistically significant correlation was found (p = 0.327). Conclusions. Our study supports the presence of motor endplate dysfunction in migraines, as indicated by previous literature, particularly in migraines with aura when compared to individuals without aura and controls. This finding aligns with the concept that this dysfunction may stem from a channelopathy associated with a genetic predisposition. Additionally, we found no clinical relationship between the neuromuscular disorder, the severity of the disease, and its disability. [ABSTRACT FROM AUTHOR]

While physical performance has long been thought to be limited only by physiological factors, many experiments denote that psychological ones can also influence it. Specifically, the deception paradigm investigates the effect of psychological factors on performance by manipulating a psychological variable unbeknownst to the subjects. For example, during a physical exercise performed to failure, previous results revealed an improvement in performance (i.e., holding time) when the clock shown to the subjects was deceptively slowed down. However, the underlying neurophysiological changes supporting this performance improvement due to deceptive time manipulation remain unknown. Here, we addressed this issue by investigating from a neuromuscular perspective the effect of a deceptive clock manipulation on a single‐joint isometric task conducted to failure in 24 healthy participants (11 females). Neuromuscular fatigue was assessed by pre‐ to post‐exercise changes in quadriceps maximal voluntary torque (Tmax), voluntary activation level (VAL), and potentiated twitch (TTW). Our main results indicated a significant performance improvement when the clock was slowed down (Biased: 356 ± 118 s vs. Normal: 332 ± 112 s, p =.036) but, surprisingly, without any difference in the associated neuromuscular fatigue (p >.05 and BF < 0.3 for Tmax, VAL, and TTW between both sessions). Computational modeling showed that, when observed, the holding time improvement was explained by a neuromuscular fatigue accumulation based on subjective rather than actual time. These results support a psychological influence on neuromuscular processes and contribute significantly to the literature on the mind–body influence, by challenging our understanding of fatigue. Limits of physical performance can be extended by psychological manipulation. However, the fundamental mechanisms underlying this phenomenon remain unclear. Here we explore the underlying neurophysiological changes that support performance improvement due to deceptive clock manipulation. Our results showed that fatigue accumulation followed subjective rather than real time for participants who improved their performance, thus allowing to overcome physical performance limits without increasing the generated neuromuscular fatigue. [ABSTRACT FROM AUTHOR]

We assessed aging hallmarks in skin, muscle, and adipose in the genetically diverse HET3 mouse, and generated a broad dataset comparing these to individual animal diagnostic SNPs from the 4 founding inbred strains of the HET3 line. For middle- and old-aged HET3 mice, we provided running wheel exercise to ensure our observations were not purely representative of sedentary animals, but age-related phenotypes were not improved with running wheel activity. Adipose tissue fibrosis, peripheral neuropathy, and loss of neuromuscular junction integrity were consistent phenotypes in older-aged HET3 mice regardless of physical activity, but aspects of these phenotypes were moderated by the SNP% contributions of the founding strains for the HET3 line. Taken together, the genetic contribution of founder strain SNPs moderated age-related phenotypes in skin and muscle innervation and were dependent on biological sex and chronological age. However, there was not a single founder strain (BALB/cJ, C57BL/6J, C3H/HeJ, DBA/2J) that appeared to drive more protection or disease-risk across aging in this mouse line, but genetic diversity in general was more protective. [Display omitted] • Genetically diverse HET3 mice are susceptible to age-related neuromuscular decline. • Voluntary exercise was ineffective at preventing age-related neuromuscular decline. • Relative contributions of HET3 founder strain genetics moderated neuropathy onset. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is a rare, autoimmune, antibody-mediated, neuromuscular disease. This study analyzed digital conversations about MG to explore unprovoked perspectives. Advanced search, data extraction, and artificial intelligence-powered algorithms were used to harvest, mine, and structure public domain digital conversations about MG from US Internet Protocol addresses (August 2021 to August 2022). Thematic analyses examined topics, mindsets, and sentiments/key drivers via natural language processing and text analytics. Findings were described by sex/gender and treatment experience with steroids or intravenous immunoglobulin (IVIg). The 13,234 conversations were extracted from message boards (51%), social media networks (22%), topical sites (21%), and blogs (6%). Sex/gender was confirmed as female in 5703 and male in 2781 conversations, and treatment experience was with steroids in 3255 and IVIg in 2106 conversations. Topics focused on diagnosis (29%), living with MG (28%), symptoms (24%), and treatment (19%). Within 3176 conversations about symptoms, eye problems (21%), facial muscle problems (18%), and fatigue (18%) were most commonly described. Negative sentiments about MG were expressed in 59% of conversations, with only 2% considered positive. Negative conversations were dominated by themes of impact on life (29%), misdiagnosis problems (27%), treatment issues (24%), and symptom severity (20%). Impact on life was a key driver of negativity in conversations by both men (27%) and women (34%), and treatment issues was a dominant theme in conversations by steroid-treated (29%) and IVIg-treated (31%) patients. Of 1382 conversations discussing treatment barriers, 36% focused on side effects, 33% on lack of efficacy, 21% on misdiagnosis, and 10% on cost/insurance. Side effects formed the main barrier in conversations by both steroid-treated and IVIg-treated patients. Capturing the patient voice via digital conversations reveals a high degree of concern related to burden of disease, misdiagnosis, and common MG treatments among those with MG, pointing to a need for treatment options that can improve quality of life. [ABSTRACT FROM AUTHOR]

Background: Residual neuromuscular blockade (rNMB) remains a persistent and preventable problem, with serious risks. Methods: Our objective was to describe and assess patterns in the use of neuromuscular blocking agents (NMBAs), neuromuscular transmission (NMT) monitoring, and factors associated with the use of sugammadex. We performed a retrospective, observational cohort study based on electronic medical records in a large teaching hospital in the Netherlands that introduced an integrated NMT monitoring module with automatic recording in 2017. A total of 22,000 cases were randomly selected from all surgeries between January 2015 and December 2019 that required endotracheal intubation with the use of an NMBA. A total of 14,592 cases fulfilled all the inclusion criteria for complete analyses. Results: Relative NMBA usage remained the same over time. For rocuronium, spontaneous reversal decreased from 86 to 81%, sugammadex reversal increased from 12 to 18%. There was a decline in patients extubated in the operating room (OR) with neither documented NMT monitoring nor sugammadex-mediated reversal from 46 to 31%. The percentage of patients extubated in the OR without a documented train-of-four ratio ≥ 0.9, decreased from 77 to 56%. Several factors were independently associated with the use of sugammadex, including BMI > 30 kg/m2 (odds ratio: 1.41; 95% CI: 1.24–1.60), ASA class 3 or 4 (1.20; 1.07–1.34), age > 60 years (1.37; 1.23–1.53), duration of surgery < 120 min (3.01; 2.68–3.38), emergency surgery (1.83; 1.60–2.09), laparoscopic surgery (2.01; 1.71–2.36), open abdominal/thoracic surgery (1.56; 1.38–1.78), NMT monitoring used (5.31; 4.63–6.08), total dose of rocuronium (1.99; 1.76–2.25), and (inversely) use of inhalational anaesthetics (0.88; 0.79–0.99). Conclusion: Our data demonstrate that the implementation of NMT monitoring with automatic recording coincides with a gradual increase in the (documented) use of NMT monitoring and an increased use of sugammadex with a more precise dose. Factors associated with sugammadex use include higher age, ASA score, BMI, abdominal and thoracic surgery, higher rocuronium doses, emergency surgery and the use of NMT monitoring. Trial registration N/A. Key points: • Introduction of NMT monitoring with automatic recording coincides with an increase in (documented) use of NMT monitoring. • Sugammadex is more frequently used in patients with a presumed higher a priori risk of pulmonary complications. • Despite increased NMT monitoring and use of sugammadex a significant percentage of patients remain at potential risk of rNMB. [ABSTRACT FROM AUTHOR]

Diabetic neuropathy is the most common complication of diabetes and lacks effective treatments. Although sensory dysfunction during the early stages of diabetes has been extensively studied in various animal models, the functional and morphological alterations in sensory and motor systems during late stages of diabetes remain largely unexplored. In the current work, we examined the influence of diabetes on sensory and motor function as well as morphological changes in late stages of diabetes. The obese diabetic Leprdb/db mice (db/db) were used for behavioral assessments and subsequent morphological examinations. The db/db mice exhibited severe sensory and motor behavioral defects at the age of 32 weeks, including significantly higher mechanical withdrawal threshold and thermal latency of hindpaws compared with agematched nondiabetic control animals. The impaired response to noxious stimuli was mainly associated with the remarkable loss of epidermal sensory fibers, particularly CGRP-positive nociceptive fibers. Unexpectedly, the area of CGRPpositive terminals in the spinal dorsal horn was dramatically increased in diabetic mice, which was presumably associated with microglial activation. In addition, the db/db mice showed significantly more foot slips and took longer time during the beam-walking examination compared with controls. Meanwhile, the running duration in the rotarod test was markedly reduced in db/db mice. The observed sensorimotor deficits and motor dysfunction were largely attributed to abnormal sensory feedback and muscle atrophy as well as attenuated neuromuscular transmission in aged diabetic mice. Morphological analysis of neuromuscular junctions (NMJs) demonstrated partial denervation of NMJs and obvious fragmentation of acetylcholine receptors (AChRs). Intrafusal muscle atrophy and abnormal muscle spindle innervation were also detected in db/db mice. Additionally, the number of VGLUT1-positive excitatory boutons on motor neurons was profoundly increased in aged diabetic mice as compared to controls. Nevertheless, inhibitory synaptic inputs onto motor neurons were similar between the two groups. This excitation-inhibition imbalance in synaptic transmission might be implicated in the disturbed locomotion. Collectively, these results suggest that severe sensory and motor deficits are present in late stages of diabetes. This study contributes to our understanding of mechanisms underlying neurological dysfunction during diabetes progression and helps to identify novel therapeutic interventions for patients with diabetic neuropathy. [ABSTRACT FROM AUTHOR]

Myasthenia gravis (MG) is an autoimmune disease in which autoantibodies target structures within the neuromuscular junction, affecting neuromuscular transmission. Muscle-specific tyrosine kinase receptor-associated MG (MuSK-MG) is a rare, often more severe, subtype of the disease with different pathogenesis and specific clinical features. It is characterized by a more severe clinical course, more frequent complications, and often inadequate response to treatment. Here, we review the current state of knowledge about potential pathomechanisms of the MuSK-MG and their therapeutic implications as well as ongoing research in this field, with reference to key points of immune-mediated processes involved in the background of myasthenia gravis. [ABSTRACT FROM AUTHOR]

Background: Neurovascular cells have wide-ranging implications on skeletal muscle biology regulating myogenesis, maturation, and regeneration. Although several in vitro studies have investigated how motor neurons and endothelial cells interact with skeletal myocytes independently, there is limited knowledge about the combined effect of neural and vascular cells on muscle maturation and development. Methods: Here, we report a triculture system comprising human-induced pluripotent stem cell (iPSC)-derived skeletal myocytes, human iPSC-derived motor neurons, and primary human endothelial cells maintained under controlled media conditions. Briefly, iPSCs were differentiated to generate skeletal muscle progenitor cells (SMPCs). These SMPCs were seeded at a density of 5 × 104 cells/well in 12-well plates and allowed to differentiate for 7 days before adding iPSC-derived motor neurons at a concentration of 0.5 × 104 cells/well. The neuromuscular coculture was maintained for another 7 days in coculture media before addition of primary human umbilical vein endothelial cells (HUVEC) also at 0.5 × 104 cells/well. The triculture was maintained for another 7 days in triculture media comprising equal portions of muscle differentiation media, coculture media, and vascular media. Extensive morphological, genetic, and molecular characterization was performed to understand the combined and individual effects of neural and vascular cells on skeletal muscle maturation. Results: We observed that motor neurons independently promoted myofiber fusion, upregulated neuromuscular junction genes, and maintained a molecular niche supportive of muscle maturation. Endothelial cells independently did not support myofiber fusion and downregulated expression of LRP4 but did promote expression of type II specific myosin isoforms. However, neurovascular cells in combination exhibited additive increases in myofiber fusion and length, enhanced production of Agrin, along with upregulation of several key genes like MUSK, RAPSYN, DOK-7, and SLC2A4. Interestingly, more divergent effects were observed in expression of genes like MYH8, MYH1, MYH2, MYH4, and LRP4 and secretion of key molecular factors like amphiregulin and IGFBP-4. Conclusions: Neurovascular cells when cultured in combination with skeletal myocytes promoted myocyte fusion with concomitant increase in expression of various neuromuscular genes. This triculture system may be used to gain a deeper understanding of the effects of the neurovascular niche on skeletal muscle biology and pathophysiology. [ABSTRACT FROM AUTHOR]

Lambert–Eaton myasthenic syndrome (LEMS) is a rare paraneoplastic neurological syndrome of the neuromuscular transmission. The symptoms often progress slowly and can be misdiagnosed in early stage. Seropositive SOX‐1 antibodies are support for the diagnosis of LEMS and have high specificity for small cell lung cancer (SCLC). In this paper, we report a case of a 56‐year‐old man with smoking history who was admitted to hospital with progressive muscle weakness of the proximal legs. LEMS was diagnosed by repetitive nerve stimulation (RNS) testing and seropositive SOX‐1 antibodies. Primary screening with chest computed tomography (CT) and integrated PET/CT did not reveal any tumor. After continuous follow‐up, SCLC was found by chest CT and confirmed with pathological examination 10 months after the diagnosis of LEMS. Long‐term follow‐up and screening for occult SCLC in LEMS patients with positive SOX‐1 antibodies are very important. [ABSTRACT FROM AUTHOR]

• Under condition of compromised neuromuscular transmission, recovery of the readily releasable pool of acetylcholine is insufficient to maintain peak force production during functional movement. • Our data suggest that CMAP decrement more clearly reflect weakness rather than fatigability. • Even very slight activity may impact the sensitivity of RNS recordings. Everyday physical activities, such as walking, are enabled by repeated skeletal muscle contractions and require a well-functioning neuromuscular transmission. In myasthenic disorders, activities of daily living are debilitated by a compromised neuromuscular transmission leading to muscle weakness and fatiguability in patients. To enable physical activity, acetylcholine (ACh) is released repeatedly from the motor nerve, however, the role of the nerve terminals' capacity to sustain ACh release to support repetitive contractions under compromised neuromuscular transmission remains unclear. To explore this, we studied synaptic and contractile function during repeated contractions in healthy rat skeletal muscles under conditions of pharmacological induced compromised neuromuscular transmission. Using recordings of endplate potentials, compound muscle action potential (CMAP) and force production in isolated skeletal muscles and living, anesthetized animals, we found that force and CMAP were markedly reduced by even very light activity performed up to 5 s prior to contraction showing that recovery of ACh release was insufficient to maintain synaptic transmission strength. Our results suggest that the timing of depletion and restoration of ACh release may impact clinical signs of weakness and fatigability in patients with impaired neuromuscular transmission and affect the sensitivity of electromyographic recordings in the clinic. [ABSTRACT FROM AUTHOR]