Muscle Fibers Research Articles

The impact of mitokine MOTS-c administration on the soleus muscle of rats subjected to a 7-day hindlimb suspension.

The aim of the study was to investigate the effect of MOTS-c on the key functional alterations in the rat soleus muscle during 7-day unloading - the transformation of slow fibers into fast ones, atrophy and increased fatigue. We daily intraperitoneally injected male Wistar rats with a short mitochondrial peptide MOTS-c during 7-day unloading of their hind limbs. After the end of the experiment, we conducted an ex vivo fatigue test of soleus muscle and showed that the MOTS-c administration prevents increased fatigue during 7-day hind limb unloading. Also, using immunohistochemical analysis, we showed that MOTS-c prevents the transformation of slow fibers into fast ones, mitigates the slow muscle atrophy fibers (but not fast ones) of the soleus muscle. In the group receiving MOTS-c, the decrease in Akt and GSK3β phosphorylation was prevented, and the 18S and 28S rRNA levels were at the control level. The ubiquitin ligases MuRF and Atrogin-1 mRNA were also reduced compared to the hindlimb unloading group with placebo. In addition, MOTS-c prevented a decrease in the expression of a few mitochondrial biogenesis parameters and the level of ACC phosphorylation (AMPK target). Thus, the MOTS-C injections during hind limb unloading lead to the normalization of several protein synthesis and degradation processes and support the expression of genes that ensure muscle resistance to fatigue.

Adolescent late-onset riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency manifesting with severe multi-organ failure: a case report

BackgroundMultiple acyl-CoA dehydrogenase deficiency (MADD) is a rare autosomal recessive disorder characterized by dysfunctional acyl-CoA dehydrogenases, leading to lipid accumulation in various tissues, including skeletal muscles, liver, and cardiac muscles, etc. Late-onset MADD presents with progressive muscular symptoms (muscle weakness, atrophy, and myalgia) and even multisystem disorders (metabolic encephalopathy, dilated cardiomyopathy, liver failure, acute kidney injury, respiratory failure, and cardiac arrest). Over the past decade, only one case of childhood late-onset MADD with severe multi-organ failure has been reported.Case presentationWe report a 15-year-old girl with worsening muscle weakness, atrophy, myalgia, hepatic insufficiency, respiratory failure and even cardiac arrest. Laboratory tests showed significantly elevated levels of creatine kinase MB isoenzyme (CK-MB) and lactate dehydrogenase (LDH). A weakly positive serum small ubiquitin-like modifier 1 activating enzyme (SAE1) antibody suggested antibody-negative polymyositis (PM), but serum acylcarnitine analysis indicated increased concentrations of various acylcarnitines, while urine organic acids was normal. Muscle biopsy revealed significant lipid deposition within muscle fibers pointing to the diagnosis of lipid storage myopathy (LSM). Genetic testing identified a homozygous c.250G>A (p.Ala84Thr) mutation in electron transfer flavoprotein dehydrogenase (ETFDH), inherited from her parents. Although this pathogenic mutation is known in MADD, it has not been associated with adolescent late-onset MADD with severe multi-organ failure. After riboflavin supplementation, the patient regained mobility without ventilator support, with no recurrence of myopathic symptoms upon follow-up.ConclusionMADD is a rare but treatable disease and its diagnosis is challenging due to its high clinical heterogeneity. Therefore, based on clinical, biochemical and pathological findings, gene analysis is critical for accurate diagnosis and clinical intervention, as riboflavin supplementation has shown lifesaving therapeutic benefit even in adolescent late-onset MADD with severe multi-organ failure.

Immediate Effects of Multiple Ischemic Compression Applications on Pain Sensitivity and Biomechanical Properties of Myofascial Trigger Points

Background: Myofascial trigger points (MTrPs) are hyperirritable spots within taut bands of skeletal muscle fibers, often developing in overloaded muscles. Ischemic compression (IC) is a frequently used therapeutic technique for MTrP treatment. Material and Methods: Seventy-nine participants with MTrPs in the upper trapezius muscle were included. Three IC protocols were used. In group 1, the compression force was increased once; in group 2, twice; and in group 3, three times—each time up to the pain threshold, then held constant until the pain subsided. Evaluations included pressure pain threshold (PPT), pressure pain perception (PPP), and myotonometric measurements. Results: PPT values increased significantly in group 2 (p = 0.009) and group 3 (p = 0.009), while PPP values decreased significantly in both groups (group 2: p = 0.016; group 3: p = 0.041) post-intervention. Group 1 showed a significant reduction in muscle tone (p < 0.001), and group 2 in muscle stiffness (p = 0.036). Muscle elasticity significantly improved in all groups: group 1 (p = 0.022), group 2 (p = 0.001), and group 3 (p = 0.042). Conclusions: IC applied with a constant force at the individual’s pain perception threshold effectively elevates the pain threshold and enhances the biomechanical parameters of muscle fibers in the trigger point area.

International Symposium on Ruminant Physiology: Nutrient signaling to skeletal muscle and adipose tissue.

Accretion of key carcass tissues such as skeletal muscle and adipose tissue is a direct effect of the specific nutrients available to support the growth and development of these key tissues. Whereas these nutrients vary greatly, many often are key regulators of important cell signaling pathways that regulate the growth and differentiation of these tissues. Postnatal skeletal muscle growth is a result of hypertrophy of the existing skeletal muscle fibers in animals. A major driver of skeletal muscle hypertrophy is protein accretion in the existing muscle fibers. This is a result of the balance between rate of protein synthesis and rate of protein degradation. Certain signaling pathways can alter the myosin heavy chain (MyHC) isoform type in postnatal skeletal muscle. Alterations in the various MyHC isoforms result in different degrees of postnatal skeletal muscle hypertrophy. An enzyme, AMP-activated protein kinase α, has been shown to affect expression of MyHC depending on sources and availability of energy to the skeletal muscle. The mTOR signaling pathway has been shown to be a critical regulator of protein synthesis in tissues such as skeletal muscle. Different components of this mTOR pathway are regulated by key nutrients such as individual AA. In many meat animals, such as cattle and sheep, there are different types of adipose tissue depots that grow and differentiate differently from each other. Two key types of adipose tissue in ruminants that have economic importance are subcutaneous and intramuscular adipose tissue. Many of the genes that control preadipocyte differentiation of these different adipose tissues in cattle are regulated by fatty acids circulating in plasma. It appeared that various fatty acids could affect cell signaling through a membrane bound G protein-coupled receptor signaling pathway. These nutrients, as well as micronutrients such as chromium, all have economic viability in the cattle feeding industry.

The role of electromyography in postoperative total knee arthroplasty: A systematic review.

The role of electromyography in postoperative total knee arthroplasty: A systematic review.

Bu-zhong-yi-qi decoction regulates JNK/c-JUN signaling pathway to improve skeletal muscle atrophy caused by cancer cachexia.

Bu-zhong-yi-qi decoction regulates JNK/c-JUN signaling pathway to improve skeletal muscle atrophy caused by cancer cachexia.

Differentially abundant proteins, metabolites, and lipid molecules in spaghetti meat compared to normal chicken breast meat: Multiomics analysis.

Differentially abundant proteins, metabolites, and lipid molecules in spaghetti meat compared to normal chicken breast meat: Multiomics analysis.

The extract of chrysanthemum flos mitigates post-stroke sarcopenia by inhibiting PANoptosis and restoring muscle homeostasis.

The extract of chrysanthemum flos mitigates post-stroke sarcopenia by inhibiting PANoptosis and restoring muscle homeostasis.

An innovative method of vacuum cooling for cooked pork meat: Uninterrupted operation between immersion vacuum cooling and vacuum cooling.

An innovative method of vacuum cooling for cooked pork meat: Uninterrupted operation between immersion vacuum cooling and vacuum cooling.

Prolonged sepsis triggers abnormal mitochondrial dynamics in the limb muscles and diaphragm.

Mitochondrial dysfunction is considered as a major trigger of sepsis-induced intensive care unit-acquired weakness (ICU-AW), but the precise role of impaired mitochondrial dynamics in sepsis-induced ICU-AW remains unclear. The cecal ligation and puncture (CLP) model was used to induce sepsis in mice. Fluid resuscitation and antibiotic treatment were used to establish a 5-day duration sepsis model, with sham-operated animals serving as controls. The muscle function of the diaphragm (DM) and tibialis anterior (TA) was assessed individually. Transmission electron microscopy (TEM) was used to observe changes in mitochondrial ultrastructure and measure the morphological parameters. Western blot analysis and quantitative real-time polymerase chain reaction were used to examine the expression of mitochondrial fusion and fission proteins and genes in DM and TA muscles. Additionally, inflammation and apoptosis were assessed in these muscles by measuring the level of pro-inflammatory cytokines and apoptotic DNA degradation, respectively. Mice subjected to CLP developed severe sepsis. Limb muscle dysfunction was more severe than that of the DM, as indicated by a greater reductions in compound muscle action potential, strength, fatigue index, and muscle fiber cross-sectional area. TEM analysis revealed sepsis-induced intermyofibrillar mitochondrial fragmentation and accumulation of injury. Both muscles showed reduced levels of Opa1 and Mfn2 mRNA and protein, and increased levels of Fis1 mRNA and protein. Correlation analysis revealed significant associations between muscle strength and Opa1, Mfn2, and Opa1/Drp1 at 5days post-sepsis. Surviving mice at 5days showed persistent inflammation, injury, and apoptosis in both muscles, but were more pronounced in the TA muscle. Prolonged sepsis leads to an impairment in mitochondrial dynamics, resulting in skeletal muscle weakness and atrophy, which may be one of the possible mechanisms of sepsis-induced ICU-AW.

Effects of environmental temperature on growth performance, muscle fiber structure, fatty acid composition, and gene expression in ducks.

Effects of environmental temperature on growth performance, muscle fiber structure, fatty acid composition, and gene expression in ducks.

Central optical power of the isolated human lens without zonular tension.

The ability to focus at near is achieved by dynamic changes in the shape of the lens of the eye. The Helmholtz hypothesis of accommodation proposes that, at distance gaze, all of the lenticular supporting zonules are at maximal tension. To bring a near object into focus, this tension is reduced by action of the ciliary muscle. The resultant release of tension allows the elastic lens capsule to mold the lens into a more rounded shape, increasing both its central thickness and central optical power (COP). Based upon Helmholtz's hypothesis, complete removal of these zonules should result in a rounded shaped lens of maximal COP. Schachar has offered an alternative mechanism of accommodation based upon the distinct actions of the three different groups of lenticular zonules. Schachar believes that for distant objects, all the zonules are under the minimum tension required to maintain lens stability; however, during lenticular accommodation, equatorial zonular tension increases while, simultaneously, the anterior and posterior zonular tension decreases. The selective increase in equatorial zonular tension results from the unique orientation of the different ciliary muscle fiber groups. With this increase in equatorial zonular tension, the peripheral lens surfaces flatten, central surfaces steepen and central lens thickness and COP increase. Schachar's hypothesis would anticipate that with zonular removal, the COP of the isolated lens would be minimal and diametrically opposite to the high lens COP expected with the Helmholtz hypothesis. In order to determine the COP of the isolated human lens, we obtained, through the kindness of the authors of an independent research study, the x-y coordinates of the central sagittal lens profiles of 10 freshly isolated human lenses (donors aged 20-30 years). These coordinate data were then mathematically utilized by fitting them into Chien, Forbes, Fourier, and elliptical equations. Additionally, the coordinate data was smoothed and fit to third-degree polynomials (S4W 3rd Poly). Independent of which of these equations was employed, within central optical zone diameters of [Formula: see text] 3 mm, the COP was found to be minimal. Since the S4W 3rd Poly provided the best fit, it was used to represent lens surfaces in optically modeled eyes. In all modeled eyes, Zernike spherical aberration (SA) coefficients were positive. These findings are consistent with in vivo measurements of SA obtained from human eyes while viewing distant visual objects. Having thus demonstrated that freshly removed human lenses, free of zonular tension, have their least COP, it is likely that this condition mimics the physiologic status of the human lens in the eye while attending to the most distant visual objects. In an independent, companion paper, we observed, using interferometric measurements of surface radius of curvatures of 12 fresh, isolated human lenses, obtained from donors aged 20-30 years, that the minimal COP was also associated with the unaccommodated state in vivo.

The differential response in fascicle behaviors of the individual plantarflexors to the post-activation potentiation.

The differential response in fascicle behaviors of the individual plantarflexors to the post-activation potentiation.

Metformin inhibits muscle atrophy through the PI3K/AKT/mTOR pathway in a rat model of acute rotator cuff tears.

Metformin inhibits muscle atrophy through the PI3K/AKT/mTOR pathway in a rat model of acute rotator cuff tears.

Transcriptome analysis and CRISPR-Cas9-mediated mutagenesis identify gpr116 as a candidate gene for growth reduction in grass carp (Ctenopharyngodon idella).

Transcriptome analysis and CRISPR-Cas9-mediated mutagenesis identify gpr116 as a candidate gene for growth reduction in grass carp (Ctenopharyngodon idella).

SERCA activation prevents Ca2+ and ATP upregulation during 3-day soleus muscle unloading in rats.

The imbalance in the ratio of protein synthesis versus protein degradation results in skeletal muscle atrophy following unloading. The onset of these processes is regulated by the sarcoplasmic concentrations of ATP and calcium (Ca2+). We tested the hypothesis that unloading-induced inactivation of sarcoendoplasmic reticulum calcium ATPase (SERCA) results in raised Ca2+ concentrations, triggering catabolic processes. CDN1163, an activator of SERCA, was used to test this hypothesis. Three groups of male rats were used: control rats with intraperitoneal injection of placebo (C), 3 days of unloading with placebo injection (3HS), and 3 days of unloading injected with CDN1163 (3HSC). Treatment with CDN1163 during 3 days of soleus muscle unloading prevented the upregulation of Ca2+ and ATP and the slow-to-fast shift in muscle fiber composition. This treatment blocked the decrease in the phosphorylation of the anabolic markers [glycogen synthase kinase-3β (GSK3β), eukaryotic translation elongation factor 2 (eEF2), and ribosomal protein S6 (S6, Ser240/244/Ser235/236)], and therefore it is likely that it improved the efficiency of translation in the unloaded muscle, but it did not affect mTORC1-dependent signaling. Treatment with CDN1163 also modulated the regulation of the Ca2+-dependent signaling in muscle during unloading via SERCA1 and calsequestrin 2 (CSQ2) and changes in the calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylation and the content of inositol 1,4,5-trisphosphate receptor (IP3R). In addition, CDN1163 prevented the upregulation of the mRNA expression of muscle-specific RING finger protein 1 (MuRF1) [but not ubiquitin ligase muscle atrophy F-box (MAFbx)] and attenuated the increase of casitas B lymphoma-b (Cbl-b) and ubiquitin mRNA expression during unloading. Activation of SERCA with CDN1163 prevents the upregulation of Ca2+ and ATP, as well as calcium-dependent and ubiquitin-proteasome pathways markers, and improves protein translation efficiency in 3-day unloaded soleus muscle.NEW & NOTEWORTHY A hypothesis was tested that unloading-induced inactivation of SERCA results in the accumulation of increased Ca2+ concentrations and activation of catabolic processes. CDN1163, an activator of SERCA, was used to test this hypothesis. CDN1163 prevented the decrease in phosphorylation of anabolic markers, which likely improved translation efficiency in unloaded muscle. CDN1163 prevented unloading-induced upregulation of mRNA expression of MuRF1 (but not MAFbx) and attenuated the increase of Cbl-b and ubiquitin mRNA expression.

Wheat alkylresorcinols regulate muscle fiber type conversion and myogenic differentiation via miR-34a/SIRT1 axis.

Alkylresorcinols (ARs) are phenolic lipids and widely distributed in whole grains such as wheat and rye. Obesity-induced skeletal muscle dysregulation is exhibited as muscle weakness and muscle atrophy. ARs have been demonstrated to mitigate muscle dysfunction, while their potential role in modulating myotube differentiation and myofiber type transition remains unclear. This study employed palmitic acid-treated C2C12 cells and high-fat diet (HFD)-induced murine models to elucidate the underlying mechanisms through which ARs potentially ameliorate skeletal muscle impairment associated with obesity. The results showed that ARs significantly increased exercise capacity of HFD-fed mice. The transformation from fast-twitch myofibers to slow-twitch myofibers, muscle growth and differentiation were improved by ARs treatment in obese mice. The expression levels of MyoD, MyoG and slow-MyHC proteins were upregulated, and the expression levels of MSTN and fast-MyHC proteins were downregulated after ARsintervention. Furthermore, ARs exhibited beneficial effects by regulating the miR-34a/SIRT1 axis which was evidenced by inhibiting the level of miR-34a and increasing the level of downstream SIRT1. Additionally, the expression of MyoD, MyoG and slow-MyHC proteins was decreased in miR-34a mimic-transfected C2C12 cells, while ARs pretreatment abolished this trend. These findings indicate that ARs exert essential roles in obesity-associated skeletal muscle dysfunction via the miR-34a/SIRT1 axis. © 2025 Society of Chemical Industry.

Multi-omics insights into the mechanisms of muscle damage induced by molybdenum exposure in goats.

Multi-omics insights into the mechanisms of muscle damage induced by molybdenum exposure in goats.

Protocol for a Trial to Assess the Efficacy and Applicability of Isometric Strength Training in Older Adults with Sarcopenia and Dynapenia

Background: Sarcopenia (loss of muscle mass) and dynapenia (loss of strength) are prevalent in older adults aged 70 years and over. Both have an impact on their functional ability and quality of life, with type II muscle fibres being particularly affected. Although traditional resistance training (TRT) is effective, it presents technical difficulties and an increased risk of injury among this vulnerable population. Isometric strength training (IST) is a potentially safer, more accessible and more effective alternative. Objective: To describe the protocol of a single-arm, pre-post intervention trial designed to evaluate the efficacy and applicability of a 16-week IST programme on muscle strength, skeletal muscle mass, quality of life and applicability (safety, acceptability, perceived difficulty) in 18 older adults aged 70 years and above with a diagnosis of sarcopenia and dynapenia. The influence of genetic and environmental factors on the variability of response to IST will also be explored. Methodology: The participants, who have all been diagnosed with sarcopenia according to EWGSOP2 (European Working Group on Sarcopenia in Older People 2) criteria, will perform two IST sessions per week for 16 weeks. Each 30-min session will consist of one progressive set (total duration 45 s to 90 s) for each of the eight major muscle groups. This series will include phases at 20% and 40% of individual Maximal Voluntary Isometric Contraction (MVIC), culminating in 100% Maximal Effort (ME), using the CIEX SYSTEM machine with visual feedback. The primary outcome variables will be: change in knee extensor MVIC and change in Appendicular Skeletal Muscle Mass Index (ASMMI). Secondary variables will be measured (other components of sarcopenia, quality of life by EQ-5D-5L, use of Likert scales, posture and physiological variables), and saliva samples will be collected for exploratory genetic analyses. The main statistical analyses will be performed with t-tests for related samples or their non-parametric analogues. Discussion: This protocol details a specific IST intervention and a comprehensive evaluation plan. The results are expected to provide evidence on the feasibility and effects of IST among older adults with sarcopenia and dynapenia. Understanding individual variability in response, including genetic influence, could inform the design of more personalised and effective exercise strategies for this population in the future.

Natural Dye as an Alternative to Hematoxylin-Eosin Staining on Histological Preparations

Hematoxylin-eosin is widely utilized in the field of animal microtechniques. However, the need to develop alternative dyes from natural sources such as plants has gained attention. Several studies have shown that many plants contain secondary metabolites with the potential to be developed as natural dyes. Lonchocarpus cyanescens and Syzygium cumini are promising candidates as alternative dyes for hematoxylin, while Lawsonia inermis and Hibiscus sabdariffa have shown potential as substitute dyes for eosin. These plants contain various secondary metabolites, including anthocyanins, flavonoids, chlorophyll, betalains, alkaloids, saponins, tannins, carbohydrates, proteins, phenolics, terpenoids, quinones, coumarins, xanthones, and resins. L. cyanescens exhibits a strong binding affinity to cells and tissues, particularly testicular tissue. Dyes derived from Syzygium cumini have been shown to provide a good staining result for rat liver cells. In contrast, dyes from Lawsonia inermis can stain cytoplasmic components and muscle fibers. Additionally, the dye from Hibiscus sabdariffa is capable of staining various biological components, including sperm, nerve cells, and blood cells. The dye preparation process involved extraction from different plant organs, such as leaves, flowers, and fruit. These findings suggest that secondary metabolites from these four plants hold significant potential for development as natural dyes to replace hematoxylin-eosin in histological applications.