Muscle Contraction Research Articles

Pharmacological characterization of alpha adrenoceptor-mediated motor responses in the rat colon.

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.

Investigating Skeletal Muscle Pump Function Using Thigh EMG, Thigh NIRS, And Stroke Volume Data In The FRAILMatics Physiological Cohort

Abstract Background The pioneering female physiologist Frances Hellebrandt first highlighted the significance of the skeletal muscle pump in circulation in the 1930s. However, the mechanisms underlying the muscle pump's function remain elusive, particularly in older individuals. It is thought that during muscle contraction, increased intramuscular pressure facilitates the expulsion of blood from the muscle's veins, aiding venous return. This contraction-induced pressure gradient assists in pushing blood towards the heart, increasing preload, and subsequently stroke volume (SV). In this study we investigated muscle pump activity using continuous measurements of thigh muscle activity, thigh total haemoglobin concentration (Hb), and cardiac SV. Methods 22 individuals (aged 70.8±5.3 years, 77.3% female) recruited from a Falls and Syncope Unit (St James’s Hospital, Dublin) underwent non-invasive measurements of Hb (NIRS PortaLite, Artinis Medical Systems, The Netherlands), electromyography (EMG) (Shimmer3, Research Ltd, Ireland), and SV (Finapres Nova, Finapres Medical Systems, The Netherlands) during a 10-second thigh squeeze test. Pre-processing involved data quality checks, alignment, and resampling. 60-second regions of interest were extracted, normalised, and processed using MATLAB (R2023a, TheMathWorks, Inc., Natick, MA, USA). Cross-correlation and Granger causality analyses were conducted to explore relationships between signals. Results Thigh Hb and EMG signals lagged 8.4 and 8.5 seconds behind SV, respectively. Granger Causality analysis revealed a significant causal relationship from both Hb and EMG to SV in 68% of participants at measured lags. Conclusion The observed ~8.5-second lag between thigh measurements and SV implies a plausible temporal relationship between muscle activation and venous return, further supported by significant causal relationships found in a substantial portion of participants using Granger causality analysis. These findings underscore the importance of continued research in this area, not only for advancing our understanding of physiological mechanisms but also for informing potential clinical applications aimed at optimising cardiovascular health and function.

Development of prediction model for risks of musculoskeletal chronic lumbopelvic pain in Indian women

Chronic lumbopelvic pain (CLPP) and its associated disabilities significantly affect women's social, professional, and personal lives. However, the specific factors contributing to CLPP in women remain unclear. To address this gap, this prospective cross-sectional study aims to identify the risk factors predicting CLPP in women and develop a prediction model that can predict CLPP in women. The study was conducted across Delhi, India, where free health camps were held, and 2400 women were assessed. Among the assessed individuals, the study revealed a high prevalence rate of CLPP among Indian women, standing at 70.4%. Seven risk factors namely, hamstring muscle tightness (> 20° on passive knee extension test), increased lumbar lordosis (> 11.5 cm of the lumbar lordotic index), reduced hip flexibility (> 15 cm on bent knee fallout test), altered foot posture (≥ 20 on foot posture index score), increased perception of psychological stress (> 25 on cohen’s perceived stress scale-10 score), reduced physical activity level (< 475 metabolic/minute on international physical activity questionnaire) and reduced performance of transversus abdominis muscle (≤ 5 on deep muscle contraction scale score) strongly predict the risks of CLPP in women. Identifying these risk factors is crucial for effectively preventing and managing CLPP symptoms, especially considering its high prevalence among Indian women. Health professionals should prioritize raising awareness about CLPP and its causative factors, as well as implementing strategies for early detection and intervention.

Effect of Different Fluorescence Iabelling Methods of the Actin Cytoskeleton for Storm Application

The Abbe limit was a major challenge in optical microscopy, making it difficult to observe microscopic biological structures. However, the development of STORM, a new fluorescence localization microscopy technique, has enabled much higher resolution imaging by causing dye molecules to blink under laser light. Advances in computational analysis have further improved image processing and resolution, leading to clearer observations and a better understanding of biological structures. Actin, a common protein in eukaryotic cells, forms F-actin, a filament involved in essential processes like cell division, migration, and muscle contraction. Fluorescence labeling is crucial for visualizing F-actin and other cellular structures, allowing scientists to study these important processes. This project explored two methods to visualize actin structures in Hela cells: phalloidin labeling with Alexa-647 dye and DNA-PAINT using GFP. ThunderSTORM analysis produced normalized images for both methods, and resolution values were calculated using FRC. The results indicated that phalloidin labeling provided higher resolution but lower-quality images, while DNA-PAINT with GFP offered better-quality images but with lower resolution.

Stress triggers irritable bowel syndrome with diarrhea through a spermidine-mediated decline in type I interferon.

Irritable bowel syndrome with diarrhea (IBS-D) is a common and chronic gastrointestinal disorder that is characterized by abdominal discomfort and occasional diarrhea. The pathogenesis of IBS-D is thought to be related to a combination of factors, including psychological stress, abnormal muscle contractions, and inflammation and disorder of the gut microbiome. However, there is still a lack of comprehensive analysis of the logical regulatory correlation among these factors. In this study, we found that stress induced hyperproduction of xanthine and altered the abundance and metabolic characteristics of Lactobacillus murinus in the gut. Lactobacillus murinus-derived spermidine suppressed the basal expression of type I interferon (IFN)-α in plasmacytoid dendritic cells by inhibiting the K63-linked polyubiquitination of TRAF3. The reduction in IFN-α unrestricted the contractile function of colonic smooth muscle cells, resulting in an increase in bowel movement. Our findings provided a theoretical basis for the pathological mechanism of, and new drug targets for, stress-exposed IBS-D.

An efficient approach for EMG controlled pattern recognition system based on MUAP identification and segregation

An Electromyography (EMG) based pattern recognition system constitutes various steps of signal processing and control engineering from signal acquisition to real-time control. Efficient control of external devices largely depends on the signal processing steps executed before the final output. This work presents a new approach to signal processing using Motor Unit Action Potential (MUAP) based signal decomposition and segmentation. An MUAP is a neurological response during muscle contraction. Due to the higher contact area of surface electrodes, MUAPs from multiple muscles are captured. An MUAP generated from a single muscle usually has identical waveshapes and similar discharging rates and usually lasts for 8–15 ms. These are known as primary MUAPs. The proposed algorithm identifies and uses the primary observed MUAPs for feature extraction and classification. Firstly, noise signals are eliminated by a determined noise margin, which also separates the active muscle movement signals. Next, a novel MUAP identification algorithm is implemented to detect the MUAP trains. Then, identified primary MUAPs are used to make segments with variable widths to extract feature vectors. Based on the correlation score of all the primary MUAPs, the segmentation is performed, which results in segmentation width varying from 110–200 ms. The achieved segmentation width is lesser than the conventional overlapping and non-overlapping methods — the proposed approach results in a 20 to 50% reduction in the segmentation width. Four different classifiers are tested during the machine learning stage to investigate the performance of the proposed approach. The obtained feature sets are then used to train the Linear Discriminant Analysis (LDA), K-Nearest Neighbor (kNN), Decision Tree (DT), and Random Forest (RF) classifiers. The classifiers are tested with precision, recall, F1 score, and accuracy. The kNN and DT classifiers performed better than the LDA and RF classifiers. The maximum precision and recall are 100% while the maximum achieved accuracy is 98.56%. The comparative results show higher accuracy even at lower segmentation widths than the conventional constant window scheme. The kNN and DT classifiers provide a 5% to 15% increment in accuracy compared to the constant window segmentation-based approach.

Digital ergonomic assessment to enhance the physical resilience of human-centric manufacturing systems in Industry 5.0

The emergence of Industry 5.0 promotes the creation of human-centric values. To fulfill this objective, Internet of Things (IoT) technologies are increasingly being exploited to digitize the human factor and monitor the ergonomics of manual manufacturing systems. These digital assessments, combined with computational algorithms, contribute to the establishment of socially inclusive workplaces while offering detailed insights to safeguard the health of the aging workforce. In this scenario, this study proposes a digital architecture for evaluating the European Assembly Worksheet (EAWS) in human-centric manufacturing systems. Three distinct enabling technologies are leveraged to acquire heterogeneous data streams. A radio-frequency-based smart glove detects the operator’s interactions with the surrounding environment, while a network of marker-less cameras and a four-channel surface Electromyography (sEMG) system capture body joint movements and muscular contractions of the upper limbs, respectively. The acquired data are processed by computational algorithms to define an EAWS-driven set of Key Risk Indicators (KRIs), embedded in an ergonomic decision support system. These risk metrics highlight operator-driven process weaknesses in musculoskeletal, muscular, and material handling dimensions. Finally, the validity of the proposed digital architecture is demonstrated in an industrial-related pilot environment, where an operator assembles a piece of home furniture.

Efficacy of lower limb strengthening exercises based on different muscle contraction characteristics for knee osteoarthritis: a systematic review and network meta-analysis.

While strengthening exercises are recommended for knee osteoarthritis (KOA) treatment, the optimal type of muscle contraction remains unclear, with current research showing conflicting results. This network meta-analysis (NMA) aims to evaluate the efficacy of lower limb strengthening exercises based on different muscle contraction characteristics for KOA patients and provide clinical references. We conducted the NMA following the PRISMA-NMA. A comprehensive search of five databases (PubMed, Web of Science, CENTRAL, Embase, and SPORTDiscus) up to August 2024 identified randomized controlled trials (RCTs) investigating lower limb strengthening exercises in KOA patients. Control groups included receiving usual care, only providing health education, or no intervention at all. Outcomes analyzed included pain, physical function, quality of life, and muscle strength. Forty-one studies (2,251 participants) were included. Twenty-eight studies used rigorous randomization; eighteen reported allocation concealment. All had high performance bias risk due to exercise interventions. Regarding efficacy, isokinetic exercise ranked highest in pain relief (SMD = 0.70, 95% CI: 0.50-0.91, SUCRA = 82.6%), function improvement (SMD = 0.75, 95% CI: 0.57-0.92, SUCRA = 96.1%), and enhancement in muscle strength (SMD = 0.56, 95% CI: 0.34-0.78, SUCRA = 90.1%). Isometric exercise ranked highest in improving quality of life (SMD = 0.80, 95% CI: 0.28-1.31, SUCRA = 90.5%). Mixed strengthening exercise ranked lowest across all outcomes. High-frequency interventions (≥5 times/week) showed superior pain relief compared with low-frequency (≤3 times/week) for isotonic, isometric, and isokinetic exercise. This NMA suggests isokinetic exercise may be most effective for pain, function, and muscle strength in KOA patients, while isometric exercise benefits quality of life most. Mixed strengthening exercise ranked lowest across all outcomes. High-frequency interventions appear more effective than low-frequency ones. These findings support personalized KOA treatment, considering efficacy, accessibility, and patient-specific factors. Study biases, heterogeneity, and other limitations may affect result reliability. Future research should focus on high-quality studies with standardized protocols and analyze dose-response relationships to refine KOA treatment strategies. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024582525, identifier: CRD42024582525.

Ozone therapy vs. classical treatment in musculoskeletal disorders

With aging and weight gain, the population is significantly overweight and faces additional pressure on vertebral and peripheral joints (ankles, knees, hips, shoulders), which affects muscles, tendons, ligaments, and nerves. Muscle contraction, translated by pain, sends the patient to the doctor. Lumbar and cervical spine disorders occur in 70-80% of the world's population during their lifetime. They are a major problem because they reduce the quality of life and increase the costs borne by health services and patients. There are multiple therapeutic options, both classic medication and alternative treatment, to combat pain for a longer or shorter period. Relief or suppression of pain, the dominant symptom in the manifestations of degenerative arthritic diseases, is an important goal of treatment, ultimately improving the quality of life. Patients, for various reasons, frequently seek alternative therapies, especially to surgical treatment. Finding the most comprehensive treatment is often a challenge. If we consider the benefit that a treatment (therapy) should bring to the health condition, then an individualized therapeutic plan must be chosen. A retrospective study on the effects of ozone and platelet-rich plasma (PRP) treatment compared to classic medication shows the role of ozone therapy in pain relief and the beneficial effect of this therapy, especially in combination with PRP, over a longer period.

Inducible and reversible SOD2 knockdown in mouse skeletal muscle drives impaired pyruvate oxidation and reduced metabolic flexibility.

Skeletal muscle mitochondrial dysfunction is a key characteristic of aging muscle and contributes to age related diseases such as sarcopenia, frailty, and type 2 diabetes. Mitochondrial oxidative distress has been implicated as a driving factor in these age-related diseases, however whether it is a cause, or a consequence of mitochondrial dysfunction remains to be determined. The development of more flexible genetic models is an important tool to test the mechanistic role of mitochondrial oxidative stress on skeletal muscle metabolic dysfunction. We characterize a new model of inducible and reversible mitochondrial redox stress using a tetracycline controlled skeletal muscle specific short hairpin RNA targeted to superoxide dismutase 2 (iSOD2). iSOD2 KD and control (CON) animals were administered doxycycline for 3- or 12- weeks and followed for up to 24 weeks and mitochondrial respiration and muscle contraction were measured to define the time course of SOD2 KD and muscle functional changes and recovery. Maximum knockdown of SOD2 protein occurred by 6 weeks and recovered by 24 weeks after DOX treatment. Mitochondrial aconitase activity and maximum mitochondrial respiration declined in KD muscle by 12 weeks and recovered by 24 weeks. There were minimal changes in gene expression between KD and CON muscle. Twelve-week KD showed a small, but significant decrease in muscle fatigue resistance. The primary phenotype was reduced metabolic flexibility characterized by impaired pyruvate driven respiration when other substrates are present. The pyruvate dehydrogenase kinase inhibitor dichloroacetate partially restored pyruvate driven respiration, while the thiol reductant DTT did not. We use a model of inducible and reversible skeletal muscle SOD2 knockdown to demonstrate that elevated matrix superoxide reversibly impairs mitochondrial substrate flexibility characterized by impaired pyruvate oxidation. Despite the bioenergetic effect, the limited change in gene expression suggests that the elevated redox stress in this model is confined to the mitochondrial matrix.

The impact of short-term pelvic floor muscle training on the biomechanical parameters of the pelvic floor among patients with stress urinary incontinence: A pilot study

ObjectiveOur study aimed to improve the understanding of the biomechanical changes occurring in the pelvic floor due to pelvic floor muscle training (PFMT), which is responsible for improving stress urinary incontinence (SUI) symptoms. Study designIn this prospective cohort study, we examined the impact of a six-week PFMT program in women with stress or stress-predominant urinary incontinence on the biomechanical parameters of the pelvic floor. Fifty-two biomechanical parameters were measured by Vaginal Tactile Imager (VTI) at baseline and at a six-week follow-up. In addition, we have assessed the Urinary Distress Inventory (UDI-6), Incontinence Impact Questionnaire (IIQ-7), and Patient’s Global Impression of Severity (PGI-S) scores at enrolment and at six-week follow-up. We have divided our cohort into two groups, Improved Group (IG) and Not-improved Group (NIG), based on the change in UDI-6 score after six weeks and compared the biomechanical changes within and between the two groups. ResultsThe overall cohort included twenty women with stress or stress-predominant SUI based on MESA questionnaire [MESA SUI index (mean ± SD) 63.3 % ± 24.0 %, MESA UUI index (mean ± SD) 13.3 % ± 15.3 %, p < 0.01]. Nine of the 52 VTI parameters have changed significantly after six weeks of PFMT in the entire cohort. Eleven women (IG) achieved the minimum 11-point change in the UDI-6 scaled score. In IG, we found that three VTI parameters differed significantly: Parameter 1: the maximum value of force measured during the VTI probe insertion [(N, mean ± SD) 0.55 ± 0.18 vs. 0.78 ± 0.31, p < 0.049], parameter 18: the maximum gradient at the upper third of the vagina (posterior) [(kPa/mm, mean ± SD) 0.16 ± 0.05 vs. 0.36 ± 0.28, p < 0.048], and parameter 47: integral force change in the anterior compartment at reflex pelvic muscle contraction (cough) [(N, mean ± SD) 1.61 ± 0.85 vs. 1.97 ± 0.71, p < 0.045]. ConclusionOur study revealed a significant association between the improvement of strength in targeted muscle groups and a reduction in urinary incontinence symptoms. Identifying specific muscles changing PFMT provides valuable insights for specific interventions. Our findings may help to create personalized and targeted interventions to improve the quality of life of women affected by SUI.

Myokines May Be the Answer to the Beneficial Immunomodulation of Tailored Exercise-A Narrative Review.

Exercise can regulate the immune function, activate the activity of immune cells, and promote the health of the organism, but the mechanism is not clear. Skeletal muscle is a secretory organ that secretes bioactive substances known as myokines. Exercise promotes skeletal muscle contraction and the expression of myokines including irisin, IL-6, BDNF, etc. Here, we review nine myokines that are regulated by exercise. These myokines have been shown to be associated with immune responses and to regulate the proliferation, differentiation, and maturation of immune cells and enhance their function, thereby serving to improve the health of the organism. The aim of this article is to review the effects of myokines on intrinsic and adaptive immunity and the important role that exercise plays in them. It provides a theoretical basis for exercise to promote health and provides a potential mechanism for the correlation between muscle factor expression and immunity, as well as the involvement of exercise in body immunity. It also provides the possibility to find a suitable exercise training program for immune system diseases.

The neurotensin receptor 1 agonist PD149163 alleviates visceral hypersensitivity and colonic hyperpermeability in rat irritable bowel syndrome model.

An impaired intestinal barrier with the activation of corticotropin-releasing factor (CRF), Toll-like receptor 4 (TLR4), and proinflammatory cytokine signaling, resulting in visceral hypersensitivity, is a crucial aspect of irritable bowel syndrome (IBS). The gut exhibits abundant expression of neurotensin; however, its role in the pathophysiology of IBS remains uncertain. This study aimed to clarify the effects of PD149163, a specific agonist for neurotensin receptor 1 (NTR1), on visceral sensation and gut barrier in rat IBS models. The visceral pain threshold in response to colonic balloon distention was electrophysiologically determined by monitoring abdominal muscle contractions, while colonic permeability was measured by quantifying absorbed Evans blue in colonic tissue invivo in adult male Sprague-Dawley rats. We employed the rat IBS models, i.e.,lipopolysaccharide (LPS)- and CRF-induced visceral hypersensitivity and colonic hyperpermeability, and explored the effects of PD149163. Intraperitoneal PD149163 (160, 240, 320 μg kg-1) prevented LPS (1 mg kg-1, subcutaneously)-induced visceral hypersensitivity and colonic hyperpermeability dose-dependently. It also prevented the gastrointestinal changes induced by CRF (50 μg kg-1, intraperitoneally). Peripheral atropine, bicuculline (a GABAA receptor antagonist), sulpiride (a dopamine D2 receptor antagonist), astressin2-B (a CRF receptor subtype 2 [CRF2] antagonist), and intracisternal SB-334867 (an orexin 1 receptor antagonist) reversed these effects of PD149163 in the LPS model. PD149163 demonstrated an improvement in visceral hypersensitivity and colonic hyperpermeability in rat IBS models through the dopamine D2, GABAA, orexin, CRF2, and cholinergic pathways. Activation of NTR1 may modulate these gastrointestinal changes, helping to alleviate IBS symptoms.

Evaluation of the efficacy of the combination of high intensity electromagnetic field and radiofrequency in promoting lipolysis

Introduction: The organization of skeletal muscle is complex, structured in distinct layers. This organization allows skeletal muscles to respond to electrical stimuli with precise and coordinated contractions. Muscle contraction occurs through responses to electrical stimuli sent by the brain to the motor neurons in the muscle fiber, these stimuli can also be induced by technologies, one of which is the high intensity electromagnetic field, also known as the HIFEM current, leading to contractions considered to be supramaximal that cannot be achieved with normal contraction, resulting in muscle hypertrophy. Objective: This study aims to analyze the results of the combination of these technologies to reduce adipose tissue. Methods: This is a clinical, observational, cross-sectional study investigating the effectiveness of the combination of high-intensity electromagnetic field and radiofrequency technologies. The sample consisted of 6 volunteers. Conclusion: It is concluded that the combination of muscle contraction and radiofrequency technologies represents an innovative approach to fat burning, combining the efficiency of lipolysis promoted by muscle energy demand with the thermal effect of radiofrequency, reducing the thickness of the fat layer by 19.53%.

Current knowledge and scientific trends in myokines and exercise research in the context of obesity.

The relationship between exercise and obesity has attracted increasing attention from researchers worldwide in recent years. The aim of the present study was to analyze the current knowledge and scientific trends of research into myokines and exercise in the context of obesity and provide ideas for future research strategies to prevent obesity. The study conducted a comprehensive bibliometric analysis of 300 scientific publications related to myokines, exercise, and obesity from 2004 to 2024. Applying the VOSviewer tool, the analysis revealed a significant increase over time in the number of publications on these topics, with a total of 1,142 related keywords identified. Key themes identified in the analysis included molecular processes, new organokines, skeletal muscle research, model organism studies, and human studies based on sex and age differences. The study highlighted the growing interest in the molecular mechanisms of obesity and role of myokines. Results showed a substantial increase in publications from 2014 to 2024, with a focus on new organokines (myokines, adipokines) and animal models. The analysis underscored the importance of myokines in modulating metabolic processes and their potential therapeutic implications in managing non-communicable diseases such as obesity. Furthermore, the study revealed the close relationship between exercise, myokine production, and regulation of metabolism, stress response, and inflammation. In conclusion, over the last years, increasing research interest has been focused on the molecular mechanisms of obesity and benefits of exercise, and probably will be focused on a set of myokines released during muscle contraction. A newly identified myokines has emerged as a promising marker for the prevention and control of obesity.

Automated Microfluidics-Assisted Hydrogel-Based Wet-Spinning for the Biofabrication of Biomimetic Engineered Myotendinous Junction.

The muscle-tendon junction (MTJ) plays a pivotal role in efficiently converting the muscular contraction into a controlled skeletal movement through the tendon. Given its complex biomechanical intricacy, the biofabrication of such tissue interface represents a significant challenge in the field of musculoskeletal tissue engineering. Herein, a novel method to produce MTJ-like hydrogel yarns using a microfluidics-assisted 3D rotary wet-spinning strategy is developed. Optimization of flow rates, rotational speed, and delivery time of bioinks enables the production of highly compartmentalized scaffolds that recapitulate the muscle, tendon, and the transient MTJ-like region. Additionally, such biofabrication parameters are validated in terms of cellular response by promoting an optimal uniaxial alignment for both muscle and tendon precursor cells. By sequentially wet-spinning C2C12 myoblasts and NIH 3T3 fibroblasts, a gradient-patterned cellular arrangement mirroring the intrinsic biological heterogeneity of the MTJ is successfully obtained. The immunofluorescence assessment further reveals the localized expression of tissue-specific markers, including myosin heavy chain and collagen type I/III, which demonstrate muscle and tenogenic tissue maturation, respectively. Remarkably, the muscle-tendon transition zone exhibits finger-like projection of the multinucleated myotubes in the tenogenic compartment, epitomizing the MTJ signature architecture.

Big data in myoelectric control: large multi-user models enable robust zero-shot EMG-based discrete gesture recognition.

Myoelectric control, the use of electromyogram (EMG) signals generated during muscle contractions to control a system or device, is a promising input, enabling always-available control for emerging ubiquitous computing applications. However, its widespread use has historically been limited by the need for user-specific machine learning models because of behavioural and physiological differences between users. Leveraging the publicly available 612-user EMG-EPN612 dataset, this work dispels this notion, showing that true zero-shot cross-user myoelectric control is achievable without user-specific training. By taking a discrete approach to classification (i.e., recognizing the entire dynamic gesture as a single event), a classification accuracy of 93.0% for six gestures was achieved on a set of 306 unseen users, showing that big data approaches can enable robust cross-user myoelectric control. By organizing the results into a series of mini-studies, this work provides an in-depth analysis of discrete cross-user models to answer unknown questions and uncover new research directions. In particular, this work explores the number of participants required to build cross-user models, the impact of transfer learning for fine-tuning these models, and the effects of under-represented end-user demographics in the training data, among other issues. Additionally, in order to further evaluate the performance of the developed cross-user models, a completely new dataset was created (using the same recording device) that includes known covariate factors such as cross-day use and limb-position variability. The results show that the large data models can effectively generalize to new datasets and mitigate the impact of common confounding factors that have historically limited the adoption of EMG-based inputs.

Effect of biofeedback pelvic floor training on urodynamic study in children with detrusor sphincter dyssynergia

ABSTRACT Introduction Detrusor sphincter dyssynergia (DSD) is the urodynamic description of bladder outlet obstruction from detrusor muscle contraction with concomitant involuntary urethral sphincter activation. DSD is associated with neurologic conditions such as spina bifida. It is associated with urinary incontinence (UI), nocturnal enuresis, urgency, intermittency, and recurrent urinary tract infections (UTIs). The Aim of this Study It aims to assess the efficacy of biofeedback (BF) for achieving perineal synergy and improving symptoms in thirty children with refractory DSD who failed to improve with medical treatment in the last 2 to 3 years. Material and Methods Thirty children (20 girls and 10 boys) aged 6–18 years (mean: 9.2 ± 2.2 yrs) with refractory DSD who failed to show improvement after 2–3 years of medical treatment with recurrent UTI and failure to emptying completely their bladder using urodynamic study. After patients understood the concept of BF pelvic floor training were regularly scheduled twice weekly for up to 3 months. Improvement was assessed using interview with parents after 3 months with measurement of manomeric pelvic floor muscles (PFMs) during straining and urodynamic study. Results Seven (23.3%) of the 30 children had daytime UI and 11 (36.7%) had nighttime incontinence. 4/30 (13.3%) children had increased urgency and 5 (16.7%) had straining intermittency and 3% (10%) had Dysuria. After 3 months of BF pelvic floor training 7/30 (23.3%) of children were fully responsive 100% decrease of symptoms, 14/30 (46%) responded more than 90% decrease of their symptoms, 7/30 (23.3%) of children responded partial decrease of symptoms and 2/30 (0 to 49%) decrease of symptoms to BF pelvic floor training. Conclusions BF pelvic floor training is an effective therapeutic option for children with refectory DSD. It improves symptoms of children with DSD with decreased UTIs through decreasing pressure of PFMs during urination.

Distinct Genomic Expression Signatures after Low-Force Electrically Induced Exercises in Persons with Spinal Cord Injury.

People with a spinal cord injury are at an increased risk of metabolic dysfunction due to skeletal muscle atrophy and the transition of paralyzed muscle to a glycolytic, insulin-resistant phenotype. Providing doses of exercise through electrical muscle stimulation may provide a therapeutic intervention to help restore metabolic function for people with a spinal cord injury, but high-frequency and high-force electrically induced muscle contractions increase fracture risk for the underlying osteoporotic skeletal system. Therefore, we investigated the acute molecular responses after a session of either a 3 Hz or 1 Hz electrically induced exercise program. Ten people with a complete spinal cord injury completed a 1 h (3 Hz) or 3 h (1 Hz) unilateral electrically induced exercise session prior to a skeletal muscle biopsy of the vastus lateralis. The number of pulses was held constant. Tissue samples were analyzed for genomic and epigenomic expression profiles. There was a strong acute response after the 3 Hz exercise leading to the upregulation of early response genes (NR4A3, PGC-1α, ABRA, IRS2, EGR1, ANKRD1, and MYC), which have prominent roles in regulating molecular pathways that control mitochondrial biogenesis, contractile protein synthesis, and metabolism. Additionally, these genes, and others, contributed to the enrichment of pathways associated with signal transduction, cellular response to stimuli, gene expression, and metabolism. While there were similar trends observed after the 1 Hz exercise, the magnitude of gene expression changes did not reach our significance thresholds, despite a constant number of stimuli delivered. There were also no robust acute changes in muscle methylation after either form of exercise. Taken together, this study supports that a dose of low-force electrically induced exercise for 1 h using a 3 Hz stimulation frequency is suitable to trigger an acute genomic response in people with chronic paralysis, consistent with an expression signature thought to improve the metabolic and contractile phenotype of paralyzed muscle, if performed on a regular basis.

Flexible and Multifunctional Pressure/Gas Sensors with Polypyrrole-Coated TPU Hierarchical Array.

A promising strategy is proposed for fabricating flexible pressure/gas sensors, which have a microprotuberance and microwrinkle structure at micropillars on their sensing substrates. The sensing substrates were prepared by compression molding thermoplastic polyurethane (TPU; an industrial grade polymer) and subsequent pyrrole polymerization. Benefiting from the hierarchical structure on the sensing substrates, the flexible sensors exhibit high performances in detecting both pressure and ammonia (NH3). Mechanism for the functionalities of the hierarchical structure of the pressure sensors was analyzed. Such unique hierarchical structure endows the interlocked pressure sensor by assembling the substrates prepared at 60 min polymerization time with a relatively high sensitivity in a wider linearity range (1.15 kPa-1, 0-800 Pa), a lower detection limit of 6.2 Pa, and shorter response and recovery times (26/28 ms). The combination of stronger interfacial interaction between the TPU and polypyrrole layer, the mutual support of the interlocked micropillars, and the inherent high resilience of TPU endows the pressure sensor with lower hysteresis, good repeatability and stability, and higher durability (10,000 cycles). The interlocked pressure sensor can detect full-range human physiological activities from weak physiological signals (such as face muscle contraction, heartbeat, and breath) to body movements (such as head, elbow, and foot movement). The gas sensor assembled with the hierarchical sensing substrate prepared at 60 min polymerization time exhibits selective, stable, and faster sensing responses to NH3. The proposed facile and cost-effective preparation strategy can be an excellent candidate for fabricating high-performance and multifunctional sensors.