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Sarcopenia, characterized by progressive and generalized loss of skeletal muscle (SkM) mass, strength, and physical performance, is a prevalent complication in type 2 diabetes (T2D). Nitric oxide (NO), a multifunctional gasotransmitter involved in whole-body glucose and insulin homeostasis, plays key roles in normal SkM physiology and function. Here, we highlight the role of NO in SkM mass maintenance and its potential contribution to the development of T2D-related sarcopenia. Physiologic NO level, primarily produced by sarcolemmal neuronal nitric oxide synthase (nNOSμ isoform), is involved in protein synthesis in muscle fibers and maintenance of SkM mass. The observed effect of nNOSμ on SkM mass is muscle-type specific and sex-dependent. Impaired NO homeostasis [due to a diminished nNOSμ-NO availability and excessive NO production through inducible NOS (iNOS) in response to atrophic stimuli, e.g., inflammatory cytokines] in SkM occurred during the development and progression of T2D, may cause sarcopenia. Theoretically, restoration of NO through nNOS overexpression, supplying NOS substrates (e.g., L-arginine and L-citrulline), phosphodiesterase (PDE) inhibition, and supplementation with NO donors (e.g., inorganic nitrate) may be potential therapeutic approaches to preserve SkM mass and prevents sarcopenia in T2D. [ABSTRACT FROM AUTHOR]

Proteins and essential fatty acids are crucial components of the human diet. However, lipids and proteins are susceptible to oxidative modification during food processing resulting in changes to their structural characteristics and functional properties. Food products rich in polyunsaturated fatty acids are highly susceptible to lipid peroxidation and generate bifunctional reactive aldehydes. Bifunctional aldehydes such as malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), and 4-oxo-2-nonenal (4-ONE) readily bind to protein nucleophiles and lead to intra- or intermolecular protein cross-linking. In comparison with lipid oxidation, the degradation of proteins by prooxidants appears to be more intricate and results in a greater diversity of oxidation products. Although individual oxidation processes involving lipids and proteins received increasing attention in the past decades, the interactions between those aldehydes and protein oxidation in food have not been extensively explored. Studies indicate that the reactions of lipid and protein oxidation may take place simultaneously or independently, but oxidation products that arose from one reaction may further interact with lipids or proteins. The present review presents a perspective on reactive aldehydes and the role of aldehydes in inducing protein oxidation in muscle foods. Emphasis is focused on the interaction mechanism of the lipid, protein, and myoglobin protein oxidations. In addition, the occurrence of aldehydes derived from lipid oxidation in food systems as well as the endogenous antioxidant peptides or amino acids in meat and plant proteins are also briefly described. [ABSTRACT FROM AUTHOR]

Murine models lacking CLOCK/BMAL1 proteins in skeletal muscle (SkM) present muscle deterioration and mitochondria abnormalities. It is unclear whether humans with lower levels of these proteins in the SkM have similar alterations. Here we evaluated the association between BMAL1 and CLOCK protein mass with mitochondrial dynamics parameters and molecular and functional SkM quality markers in males. SkM biopsies were taken from the vastus lateralis of 16 male (non‐athletes, non‐obese and non‐diabetic) subjects (8–9 a.m.). The morphology of mitochondria and their interaction with the sarcoplasmic reticulum (mitochondria‐SR) were determined using transmission electron microscopy images. Additionally, protein abundance of the OXPHOS complex, mitochondria fusion/fission regulators, mitophagy and signalling proteins related to muscle protein synthesis were measured. To evaluate the quality of SkM, the cross‐sectional area and maximal SkM strength were also measured. The results showed that BMAL1 protein mass was positively associated with mitochondria‐SR distance, mitochondria size, mitochondria cristae density and mTOR protein mass. On the other hand, CLOCK protein mass was negatively associated with mitochondria‐SR interaction, but positively associated with mitochondria complex III, OPA1 and DRP1 protein mass. Furthermore, CLOCK protein mass was positively associated with the protein synthesis signalling pathway (total mTOR, AKT and P70S6K protein mass) and SkM strength. These findings suggest that the BMAL1 and CLOCK proteins play different roles in regulating mitochondrial dynamics and SkM function in males, and that modulation of these proteins could be a potential therapeutic target for treating muscle diseases. Key points: In murine models, reductions in BMAL1 and CLOCK proteins lead to changes in mitochondria biology and a decline in muscle function. However, this association has not been explored in humans.We found that in human skeletal muscle, a decrease in BMAL1 protein mass is linked to smaller intermyofibrillar mitochondria, lower mitochondria cristae density, higher interaction between mitochondria and sarcoplasmic reticulum, and reduced mTOR protein mass.Additionally, we found that a decrease in CLOCK protein mass is associated with a higher interaction between mitochondria and sarcoplasmic reticulum, lower protein mass of OPA1 and DRP1, which regulates mitochondria fusion and fission, lower protein synthesis signalling pathway (mTOR, AKT and P70S6K protein mass), and decreased skeletal muscle strength.According to our findings in humans, which are supported by previous studies in animals, the mitochondrial dynamics and skeletal muscle function could be regulated differently by BMAL1 and CLOCK proteins. As a result, targeting the modulation of these proteins could be a potential therapeutic approach for treating muscle diseases and metabolic disorders related to muscle. [ABSTRACT FROM AUTHOR]

• Protein hydrolyzates and biopeptides can provide a source of protein with good functional properties. • PPH902 treatment significantly RTR and activate p-AMPK and inhibit adipogenesis in adipocytes. • PPH902 is an effective anti-lipogenesis and lipolysis-promoting hydrolyzate, which has the potential to develop anti-obesity products. Obesity is a chronic metabolic disease caused by unbalanced caloric intake, which has serious harm to health and increases the risk of hypertension, hyperlipidemia, diabetes and cardiovascular diseases. Previous studies have shown that Alcalase treatment-derived potato protein hydrolysate (PPH) has the effects of regulating blood pressure and blood sugar in animal experiments, and has cardioprotective, hepato-protective activity and inhibited muscle protein degradation. This study aims to screen the optimal conditions isolating potato protein hydrolysate with potential anti-obesity activity by regulating the mechanism of lipogenesis and lipolysis. 9% potato protein (PP) hydrolysed for 2 h (PPH902) shows high yield and better activity; thus, PPH902 was used in all other experiments. PPH902 at 1600 ppm does not affect the cell viability of 3T3-L1 adipocytes. PPH902 regulates the expression of lipid production-related transcription factors PPARγ, SREBP-1c, and FAS by activating AMPK, thereby inhibiting lipogenesis, and activating phosphorylated HSL to promote lipolysis to increase lipid metabolism. These results show that PPH902 is an effective anti-lipogenesis and lipolysis-promoting hydrolyzate, which has the potential to develop anti-obesity products. [ABSTRACT FROM AUTHOR]

Purpose: Reduced capillary number in skeletal muscle due to disuse can hinder the delivery of insulin and amino acid delivery to muscle cells, diminishing insulin activity and muscle protein synthesis, ultimately contributing to anabolic resistance. However, it remains unknown whether mitigating capillary regression during inactivity improves anabolic resistance. This study aimed to investigate the effect of increasing capillary number through the administration of prazosin, which can increase blood flow and prevent capillary regression, on anabolic resistance in skeletal muscle induced by disuse. Methods: Male Sprague Dawley rats were divided into control and hindlimb unloading (HU) groups, with half of each group receiving prazosin (50 mg/L) in their drinking water for 2 weeks. Histological analysis of the soleus muscles was conducted to measure the capillary-to-fiber (C/F) ratio, while western blotting was performed to measure the activation of the Akt/mTORC1 muscle protein synthesis pathway before and after insulin stimulation. Results: The C/F ratios were significantly lower in the HU and HU + Prz groups than in the control group but were significantly higher in the HU + Prz group than in the HU group. Following insulin stimulation, the phosphorylation levels of Akt, p70S6K, and S6RP increased in all groups, with a significantly greater increase observed in the HU + Prz group compared to the HU group, indicating improved molecular signaling related to muscle protein synthesis. Conclusion: Administration of prazosin during hindlimb unloading mitigated capillary regression and enhanced insulin-stimulated muscle protein synthesis response. These findings suggest that enhancing capillary number may reduce the anabolic resistance caused by muscle disuse. [ABSTRACT FROM AUTHOR]

Weekly Steroids in Muscular Dystrophy (WSiMD) was a pilot study to evaluate once weekly prednisone in patients with Limb Girdle and Becker muscular dystrophy (LGMD and BMD, respectively). At study endpoint, there were trends towards increased lean mass, reduced fat mass, reduced creatine kinase and improved motor function. The investigation was motivated by studies in mouse muscular dystrophy models in which once weekly glucocorticoid exposure enhanced muscle strength and reduced fibrosis. WSiMD participants provided blood samples for aptamer serum profiling at baseline and after 6 months of weekly steroids. A subset completed magnetic resonance (MR) evaluation of muscle at study onset and endpoint. At baseline compared to age and sex-matched healthy controls, the aggregate serum protein profile in the WSiMD cohort was dominated by muscle proteins, reflecting leak of muscle proteins into serum. Disease status produced more proteins differentially present in serum compared to steroid-treatment effect. Nonetheless, a response to prednisone was discernable in the WSiMD cohort, even at this low dose. Glucocorticoids decreased muscle proteins and increased certain immune process- and matrix-associated proteins. Muscle MR fat fraction showed trends with functional status. The prednisone-responsive markers could be used in larger trial of prednisone efficacy. [ABSTRACT FROM AUTHOR]

We examined changes in skeletal muscle protein lactylation and acetylation in response to acute resistance exercise, chronic resistance training (RT), and a single endurance cycling bout. Additionally, we performed in vitro experiments to determine if different sodium lactate treatments affect myotube protein lactylation and acetylation. The acute and chronic RT study (12 college-aged participants) consisted of 10 weeks of unilateral leg extensor RT with vastus lateralis (VL) biopsies taken at baseline, 24 h following the first RT bout, and the morning of the last day of the RT bout. For the acute cycling study (9 college-aged participants), VL biopsies were obtained before, 2 h after, and 8 h after 60 min of cycling. For in vitro experiments, C2C12 myotubes were treated with varying levels of sodium lactate, including LOW (1 mM for 24 h), HIGH (10 mM for 24 h), and PULSE (10 mM for 30 min followed by 1 mM for 23.5-h). Neither acute nor chronic RT significantly affected nuclear or cytoplasmic protein lactylation. However, cytoplasmic protein acetylation was significantly reduced following one RT bout (−15%, p = 0.002) and chronic RT (−16%, p = 0.006). Cycling did not acutely alter post-exercise global protein lactylation or acetylation patterns. Lastly, varying 24 h lactate treatments did not alter nuclear or cytoplasmic protein lactylation or acetylation, cytoplasmic protein synthesis levels, or myotube diameters. These findings continue to support the idea that exercise induces more dynamic changes in skeletal muscle protein acetylation, but not lactylation. However, further human research with more sampling timepoints and a lactylomics approach are needed to determine if, at all, different exercise modalities affect skeletal muscle protein lactylation. [ABSTRACT FROM AUTHOR]

Increased dietary salt intake is a well-established risk factor for hypertension and related cardiovascular diseases, involving complex vascular remodeling processes. However, the specific role of hypoxia-inducible factor-1α (HIF-1α) in vascular pathophysiology under high-salt conditions remains poorly understood. This study investigates the role of HIF-1α in high-salt-induced vascular remodeling using human aortic vascular smooth muscle cells (HA-VSMCs) cultured in vitro. HA-VSMCs were divided into three groups: high-salt with HIF-1α knockdown (shHIF-1α + HS), negative control (shcontrol), and high-salt (HS). Cell viability, migration, gene expression, and protein levels were evaluated. High-salt conditions significantly increased mRNA expression of α-smooth muscle actin (α-SMA), smooth muscle protein 22 (SM22), angiotensin II type 1 receptor (AT1R), collagen I, and collagen III (p < 0.0001). HIF-1α knockdown partially attenuated these increases, particularly for α-SMA, SM22, and AT1R (p < 0.01). At the protein level, high-salt exposure markedly elevated expression of collagen III, HIF-1α, osteopontin (OPN), and angiotensin II (Ang II) (p < 0.0001). HIF-1α knockdown significantly reduced the high-salt-induced increases in collagen III and HIF-1α protein levels (p < 0.001) but had a limited effect on OPN and Ang II upregulation. Interestingly, SM22 protein expression was significantly decreased under high-salt conditions (p < 0.0001), an effect partially reversed by HIF-1α knockdown (p < 0.0001). These findings demonstrate that high-salt conditions induce complex changes in gene and protein expression in HA-VSMCs, with HIF-1α playing a crucial role in mediating many of these alterations. The study highlights the differential effects of HIF-1α on various markers of vascular remodeling and suggests that HIF-1α may be a potential therapeutic target for mitigating salt-induced vascular pathology. Further research is warranted to elucidate the mechanisms underlying the HIF-1α-dependent and -independent effects observed in this study. [ABSTRACT FROM AUTHOR]

Background: Diabetes is accompanied by a high prevalence of hyposalivation, causing severe damage to oral and systemic health. Mitochondrial dynamics play important roles in the pathogenesis of various diabetic complications; however, little is known about their roles in diabetic hyposalivation. Materials and Methods: A diabetic mouse model and a high glucose (HG)‐induced diabetic submandibular gland (SMG) cell model were employed. Results: More mitochondria surrounded by autophagosomes and higher expression of mitophagy‐related proteins were detected in the SMGs of diabetic mice and HG‐treated SMG cells. In diabetic SMGs, dynamin‐related protein 1 (DRP1) was upregulated, whereas mitofusin‐2 was downregulated both in vivo and in vitro. Shortened mitochondria and impaired mitochondrial functions were observed in the HG group. A DRP1‐specific inhibitor, mdivi‐1, suppressed mitochondrial fission and mitophagy, as well as restored mitochondrial functions in the HG condition. Moreover, the interaction of F‐actin and DRP1 was enhanced in the diabetic group. Inhibiting F‐actin with cytochalasin D repaired the injured effects of HG on mitochondrial dynamics and functions. Conversely, the F‐actin‐polymerization‐inducer jasplakinolide aggravated mitochondrial fission and dysfunction. Conclusions: F‐actin contributes to HG‐evoked mitochondrial fission by interacting with DRP1, which induces mitophagy and impairs mitochondrial function in SMG cells, ultimately damaging the SMG. [ABSTRACT FROM AUTHOR]

Leucine is an essential amino acid that cannot be produced endogenously in the human body and therefore needs to be obtained from dietary sources. Leucine plays a pivotal role in stimulating muscle protein synthesis, along with isoleucine and valine, as the group of branched-chain amino acids, making them one of the most popular dietary supplements for athletes and gym-goers. The individual effects of leucine, however, have not been fully clarified, as most of the studies so far have focused on the grouped effects of branched-chain amino acids. In recent years, leucine and its metabolites have been shown to stimulate muscle protein synthesis mainly via the mammalian target of the rapamycin complex 1 signaling pathway, thereby improving muscle atrophy in cancer cachexia. Interestingly, cancer research suggests that leucine may have either anti-cancer or pro-tumorigenic effects. In the current manuscript, we aim to review leucine's roles in muscle protein synthesis, tumor suppression, and tumor progression, specifically summarizing the molecular mechanisms of leucine's action. The role of leucine is controversial in hepatocellular carcinoma, whereas its pro-tumorigenic effects have been demonstrated in breast and pancreatic cancers. In summary, leucine being used as nutritional supplement for athletes needs more attention, as its pro-oncogenic effects may have been identified by recent studies. Anti-cancer or pro-tumorigenic effects of leucine in various cancers should be further investigated to achieve clear conclusions. [ABSTRACT FROM AUTHOR]

We evaluated associations between muscle phenotype, positional role, and on‐ice performance in male U20 Danish national team ice hockey players. Sixteen players (10 forwards, six defensemen) participated in a game with activity tracking. Resting thigh muscle biopsies were analyzed for metabolic enzyme activity and protein expression linked to performance. On‐ice intermittent exercise capacity, repeated sprint ability, and maximal isometric knee‐extensor torque were also assessed. No significant position‐specific muscle phenotype characteristics were found, but forwards generally exhibited higher levels of several membrane proteins (p = 0.100–0.991). NAKα2, NAK∑, KATP, ClC‐1, and NHE1 showed significant correlations with total distance (r = 0.52–0.59, p = 0.016–0.046), however, within positions these only persisted for KATP (r = 0.70, p = 0.024) and NAKα2 (r = 0.57, p = 0.085) in forwards, where CS enzyme activity also displayed a strong association with distance covered (r = 0.75, p = 0.019). For high‐intensity skating, NAKα2 (r = 0.56, p = 0.025) and KATP (r = 0.50, p = 0.048) similarly exhibited the strongest associations, persisting within forwards (r = 0.63, p = 0.052 and r = 0.72; p = 0.018, respectively). In conclusion, although several muscle proteins involved in ion and metabolic regulation were associated with performance, only NAKα2 and KATP displayed consistent relationships within positions. Moreover, CS enzyme activity was strongly related to total distance within forwards, coherent with the proposed importance of oxidative capacity in intense intermittent exercise. [ABSTRACT FROM AUTHOR]

Strenuous physical training increases total blood volume (BV) through expansion of plasma volume (PV) and red cell volume (RCV). In contrast, exogenous erythropoietin (EPO) treatment increases RCV but decreases PV, rendering BV stable or slightly decreased. This study aimed to determine the combined effects of strenuous training and EPO treatment on BV and markers of systemic and muscle iron homeostasis. In this longitudinal study, eight healthy nonanemic males were treated with EPO (50 IU/kg body mass, three times per week, sc) across 28 days of strenuous training (4 days/wk, exercise energy expenditures of 1,334 ± 24 kcal/day) while consuming a controlled, energy-balanced diet providing 39 ± 4 mg/day iron. Before (PRE) and after (POST) intervention, BV compartments were measured using carbon monoxide rebreathing, and markers of iron homeostasis were assessed in blood and skeletal muscle (vastus lateralis). Training + EPO increased (P < 0.01) RCV (13 ± 6%) and BV (5 ± 4%), whereas PV remained unchanged (P = 0.86). The expansion of RCV was accompanied by a large decrease in whole body iron stores, as indicated by decreased (P < 0.01) ferritin (−77 ± 10%) and hepcidin (−49 ± 23%) concentrations in plasma. Training + EPO decreased (P < 0.01) muscle protein abundance of ferritin (−25 ± 20%) and increased (P < 0.05) transferrin receptor (47 ± 56%). These novel findings illustrate that strenuous training combined with EPO results in both increased total oxygen-carrying capacity and hypervolemia in young healthy males. The decrease in plasma and muscle ferritin suggests that the marked upregulation of erythropoiesis alters systemic and tissue iron homeostasis, resulting in a decline in whole body and skeletal muscle iron stores. NEW & NOTEWORTHY: Strenuous exercise training combined with erythropoietin (EPO) treatment increases blood volume, driven exclusively by red cell volume expansion. This hematological adaptation results in increased total oxygen-carrying capacity and hypervolemia. The marked upregulation of erythropoiesis with training + EPO reduces whole body iron stores and circulating hepcidin concentrations. The finding that the abundance of ferritin in muscle decreased after training + EPO suggests that muscle may release iron to support red blood cell production. [ABSTRACT FROM AUTHOR]

Branched-chain amino acids (BCAAs) are essential for muscle protein synthesis and are widely acknowledged for mitigating sarcopenia. Oligonol® (Olg), a low-molecular-weight polyphenol from Litchi chinensis, has also been found to attenuate sarcopenia by improving mitochondrial quality and positive protein turnover. This study aims to investigate the effect of Olg on BCAA-stimulated protein synthesis in sarcopenia. In sarcopenic C57BL/6 mice and senescence-accelerated mouse-prone 8 (SAMP8) mice, BCAAs were significantly decreased in skeletal muscle but increased in blood serum. Furthermore, the expressions of membrane L-type amino acid transporter 1 (LAT1) and branched-chain amino acid transaminase 2 (BCAT2) in skeletal muscle were lower in aged mice than in young mice. The administration of Olg for 8 weeks significantly increased the expressions of membrane LAT1 and BCAT2 in the skeletal muscle when compared with non-treated SAMP8 mice. We further found that BCAA deprivation via LAT1-siRNA in C2C12 myotubes inhibited the signaling of protein synthesis and facilitated ubiquitination degradation of BCAT2. In C2C12 cells mimicking sarcopenia, Olg combined with BCAA supplementation enhanced mTOR/p70S6K activity more than BCAA alone. However, blocked LAT1 by JPH203 reversed the synergistic effect of the combination of Olg and BCAAs. Taken together, changes in LAT1 and BCAT2 during aging profoundly alter BCAA availability and nutrient signaling in aged mice. Olg increases BCAA-stimulated protein synthesis via modulating BCAA transportation and BCAA catabolism. Combining Olg and BCAAs may be a useful nutritional strategy for alleviating sarcopenia. [ABSTRACT FROM AUTHOR]

Human sepsis is characterized by increased protein breakdown and changes in arginine and citrulline metabolism. However, it is unclear whether this is caused by changes in transorgan metabolism. We therefore studied the changes in protein and arginine-related metabolism on the whole body (Wb) and transorgan levels in a Pseudomonas aeruginosa-induced pig sepsis model. We studied 22 conscious pigs for 18 h during sepsis induced by infusing live bacteria (Pseudomonas aeruginosa) or after placebo infusion (Control). We used stable isotope tracers to measure Wb and skeletal muscle protein synthesis and breakdown, as well as Wb, splanchnic, skeletal muscle, hepatic, and portal-drained viscera (PDV) arginine and citrulline disposal and production rates. During sepsis, arginine Wb production (P = 0.0146), skeletal muscle release (P = 0.0035), and liver arginine uptake were elevated (P = 0.0031). Wb de novo arginine synthesis, citrulline production, and transorgan PDV release of citrulline, glutamine, and arginine did not differ between Sepsis and Control pigs. However, Wb (P < 0.0001) and muscle (P < 0.001) protein breakdown were increased, suggesting that the enhanced arginine production is predominantly derived from muscle breakdown in sepsis. In conclusion, live bacterium sepsis increases muscle arginine release and liver uptake, mirroring previous pig endotoxemia studies. In contrast to observations in humans, acute live bacterium sepsis in pigs does not change citrulline production or arterial arginine concentration. We therefore conclude that the arginine dysregulation observed in human sepsis is possibly initiated by enhanced protein catabolism and splanchnic arginine catabolism, whereas decreased arterial arginine concentration and citrulline metabolism may require more time to fully manifest in patients. NEW & NOTEWORTHY: Our work highlights that arginine availability may be largely determined by muscle breakdown and hepatic extraction in early sepsis, while citrulline production appears maintained. Additionally, our work highlights a novel ANCOVA approach for transorgan analysis to control for inherent variation in transorgan data and increase statistical sensitivity. [ABSTRACT FROM AUTHOR]

The use of hormone replacement and myostatin-based therapies in clinical trials – aimed at promoting muscle hypertrophy – has not resulted in notable advancements in muscle strength or functional performance. The decline in sex hormones that occurs with aging is closely tied to the development of sarcopenia. However, the potential adverse effects of sex hormone replacement therapy outweigh its modest advantages in mitigating muscle aging. There is no conclusive association between circulating myostatin level and muscle aging, and myostatin-based therapy does not affect muscle aging. While effective in promoting muscle growth, hypertrophic signaling compromises muscle protein quality control, exacerbating age-related muscle dysfunction. An alternative intervention to refine mechanistic target of rapamycin (mTOR) functions is proposed to benefit muscle health in the elderly. A healthy lifespan relies on independent living, in which active skeletal muscle is a critical element. The cost of not recognizing and acting earlier on unhealthy or aging muscle could be detrimental, since muscular weakness is inversely associated with all-cause mortality. Sarcopenia is characterized by a decline in skeletal muscle mass and strength and is associated with aging. Exercise is the only effective therapy to delay sarcopenia development and improve muscle health in older adults. Although numerous interventions have been proposed to reduce sarcopenia, none has yet succeeded in clinical trials. This review evaluates the biological gap between recent clinical trials targeting sarcopenia and the preclinical studies on which they are based, and suggests an alternative approach to bridge the discrepancy. [ABSTRACT FROM AUTHOR]

The preservation of harvested fish is important in fisheries production. To investigate the effect of acute cold stress on preserving the freshness of large yellow croaker, which has the highest expression of ISP2 mRNA in its muscle, under ice-temperature storage and frozen storage, acute cold stress durations were investigated first. According to the results of the above test, large yellow croakers were subjected to acute cold stress for 40 min, followed by ice-temperature storage or frozen storage. The K values, sensory attributes, and protein compositions of large yellow croaker under ice-temperature storage or frozen storage for different durations were investigated in this study. The results showed that acute cold stress treatment affects the ice-temperature storage and frozen storage of large yellow croaker. In the muscle of large yellow croaker under ice-temperature storage for 1, 2, 3, and 5 d, the K values of the acute cold stress groups were significantly lower than those of the control groups (not subjected to acute cold stress). In the muscle of large yellow croaker under frozen storage, the sensory evaluation scores of the acute cold stress groups were greater than those of the control group until a storage time of 60 d. With an extension of frozen storage, there were changes in the contents of myofibrillar protein, myogen, muscle matrix protein, and alkali-soluble protein. The myofibrillar protein, myogen, and muscle matrix protein contents of the acute cold stress groups were greater than those of the control groups after short-term frozen storage, while the alkali-soluble protein contents of the acute cold stress groups were lower than those of the control groups, except for durations of 1, 3, 15, 19, and 22 d. In addition, the K values of the acute cold stress groups were significantly lower than those of the control groups after frozen storage for 1, 2, 3, 5, 9, 15, 19, and 22 d. The results indicate that treatment with acute cold stress for 40 min affects the preservation of large yellow croaker. [ABSTRACT FROM AUTHOR]

Single‐molecule localisation microscopy (SMLM) has the potential to reveal the underlying organisation of specific molecules within supramolecular complexes and their conformations, which is not possible with conventional microscope resolution. However, the detection efficiency for fluorescent molecules in cells can be limited in SMLM, even to below 1% in thick and dense samples. Segmentation of individual complexes can also be challenging. To overcome these problems, we have developed a software package termed PERPL: Pattern Extraction from Relative Positions of Localisations. This software assesses the relative likelihoods of models for underlying patterns behind incomplete SMLM data, based on the relative positions of pairs of localisations. We review its principles and demonstrate its use on the 3D lattice of Z‐disk proteins in mammalian cardiomyocytes. We find known and novel features at ~20 nm with localisations of less than 1% of the target proteins, using mEos fluorescent protein constructs. LAY DESCRIPTION: Single‐molecule localisation microscopy (SMLM) finds the positions of fluorescently labelled molecules in cells with a precision of between 1 and 10 nm. Interpreting this data helps us to uncover how these molecules are organised within cells and within specific structures important for their cellular roles. However, imperfect fluorescent labelling and low signal‐to‐noise ratios in experimental SMLM data limit its ability to detect all of the fluorescent molecules. Sometimes less than 1% of these molecules are located with high precision, which makes determining their molecular arrangement very challenging. To overcome this challenge, we have developed a new method called PERPL: Pattern Extraction from Relative Positions of Localisations (https://github.com/AlistairCurd/PERPL‐Python3, https://www.youtube.com/watch?v=uB1aU8QC%5fZ4) to analyse this type of data. In this method, we determine the relative positions of pairs of precisely localised molecules in 3D, and determine characteristic relative positions from collecting data over multiple instances of the molecular complex in a single cell, or over multiple cells. The combination of the most common relative positions of pairs of molecules gives us information about their 3D arrangement and the structure of the complex they are found in. We then build mathematical models for the distribution of relative positions in different candidate structures, which represent hypotheses about the underlying molecular organisation. Fitting these models to the experimental data allows us to select the model most likely to represent the best hypothesis. We demonstrate this method on an eightfold symmetric protein distribution in the nuclear pore complex and on a repeating pattern in muscle cell protein arrangements found from approx. 1% and 0.1% of these molecules in different SMLM techniques. We also explore the patterns of other muscle cell proteins that are as yet less well understood. PERPL can also analyse the arrangement of more than one molecule of interest in a complex and features within standard pixelated image data that can be described by coordinates. Finally, PERPL can also be used to test systematic variability due to SMLM data acquisition techniques, when a well‐characterised sample is used, or to test the variability of a sample. [ABSTRACT FROM AUTHOR]

Sepsis-induced myopathy is one of the serious complications of sepsis, which severely affects the respiratory and peripheral motor systems of patients, reduces their quality of life, and jeopardizes their lives, as evidenced by muscle atrophy, loss of strength, and impaired regeneration after injury. The pathogenesis of sepsis-induced myopathy is complex, mainly including cytokine action, enhances free radical production in muscle, increases muscle protein hydrolysis, and decreases skeletal muscle protein synthesis, etc. The above mechanisms have been demonstrated in existing studies. However, it is still unclear how the overall pattern of gene co-expression affects the pathological process of sepsis-induced myopathy. Therefore, we intend to identify hub genes and signaling pathways. Weighted gene co-expression network analysis was our main approach to study gene expression profiles: skeletal muscle transcriptome in ICU patients with sepsis-induced multi-organ failure (GSE13205). After data pre-processing, about 15,181 genes were used to identify 13 co-expression modules. Then, 16 genes (FEM1B, KLHDC3, GPX3, NIFK, GNL2, EBNA1BP2, PES1, FBP2, PFKP, BYSL, HEATR1, WDR75, TBL3, and WDR43) were selected as the hub genes including 3 up-regulated genes and 13 down-regulated genes. Then, Gene Set Enrichment Analysis was performed to show that the hub genes were closely associated with skeletal muscle dysfunction, necrotic and apoptotic skeletal myoblasts, and apoptosis in sepsis-induced myopathy. Overall, 16 candidate biomarkers were certified as reliable features for more in-depth exploration of sepsis-induced myopathy in basic and clinical studies. [ABSTRACT FROM AUTHOR]

UNC-89 is a giant sarcomeric M-line protein required for sarcomere organization and optimal muscle function. UNC-89 contains two protein kinase domains, PK1 and PK2, separated by an elastic region. Here we show that PK2 is a canonical kinase expected to be catalytically active. C. elegans expressing UNC-89 with a lysine to alanine (KtoA) mutation to inactivate PK2 have normally organized sarcomeres and SR, and normal muscle function. PK2 KtoA mutants have fragmented mitochondria, correlated with more mitochondrially-associated DRP-1. PK2 KtoA mutants have increased ATP levels, increased glycolysis and altered levels of electron transport chain complexes. Muscle mitochondria show increased complex I and decreased complex II basal respiration, each of which cannot be uncoupled. This suggests that mutant mitochondria are already uncoupled, possibly resulting from an increased level of the uncoupling protein, UCP-4. Our results suggest signaling from sarcomeres to mitochondria, to help match energy requirements with energy production. UNC-89, a giant protein localized to muscle sarcomeres, contains 2 protein kinase domains, one of which, PK2 is a canonical kinase. A missense mutation expected to inactivate PK2 results in worms with an unexpected phenotype suggesting signaling from sarcomeres to mitochondria. [ABSTRACT FROM AUTHOR]

The document "Advances in Muscle Research in Health and Disease" published in the journal Cells highlights the critical role of muscle tissue in maintaining overall health and explores recent advancements in muscle research. Key areas of focus include myogenesis, muscle as an endocrine organ, non-invasive treatments for muscle-related diseases, and the impact of lysine on myogenic differentiation in fast and slow muscles. The research presented in this special issue provides valuable insights into muscle biology, potential therapeutic strategies, and innovative approaches for managing muscle-related diseases, ultimately aiming to improve muscle health and overall well-being. [Extracted from the article]

Myofibrillar proteins (MPs), the most important proteins in muscle, play a vital role in the texture, flavor, sensory and consumer acceptance of final muscle-based food products. Over the past several decades, conjugation of carbohydrates to MPs via glycosylation is of particular interest due to the substantial enhancement in MPs characteristics. Studying the covalent interactions between carbohydrates and MPs under various processing conditions and molecular mechanisms by which carbohydrates affect the functionalities of MPs can introduce new perspectives for design and production of muscle-based foods. However, there is no insightful and comprehensive summary of the structural, physicochemical and functional characteristics changes of MPs induced by glycosylation modification and how these changes can be adopted to potentially promote the science-based development of tailor-made muscle foods. Based on this, the functionalities of MPs as well as their practical limiting issues are initially highlighted. A comprehensive overview of fabrication strategies is then introduced. Additionally, changes in the structural and functional properties of MPs regulated by glycosylation have also been carefully summarized. On this basis, the research limitations to be solved and our perspectives for the future development of muscle-based foods are put forward. [ABSTRACT FROM AUTHOR]

Background: Crab-flavored seafood is a well-known traditional Japanese product that is sold as "imitation crab" worldwide. Although it is a low-cost, low-fat, high-protein food, there are few data on its potential health benefits. Here, we have assessed the effects of crab-flavored seafood consumption on organ weight and serum biomarkers levels in rats. Methods: Sprague–Dawley rats (male; aged 6 weeks) were fed a normal diet (n = 8) or a normal diet with 5% dried crab-flavored seafood (n = 8) for 84 days. Food intake and overall body weight were measured every week; organ weight and blood biochemistry were evaluated at the end of the administration period. Results: After 84 days, there were no significant differences in food intake, overall body weight, or organ weight between the 2 groups; however, the muscle weight of rats fed crab-flavored seafood tended to be higher than that of rats fed the normal diet. Several serum biomarkers did not differ between the 2 groups, but serum high-density lipoprotein, total bilirubin, and indirect bilirubin levels were significantly raised in rats fed crab-flavored seafood. Moreover, blood urea nitrogen was significantly lower, and some liver function parameters tended to be lower in rats fed crab-flavored seafood. Conclusions: Consumption of crab-flavored seafood may be effective for promoting muscle protein synthesis and improving serum biomarkers associated with disorders such as cardiovascular disease and stroke. Thus, crab-flavored seafood may have application as a functional food for the global management of human health. [ABSTRACT FROM AUTHOR]

Introduction: Patients with mild burns take most accounts, however, the impact of mild burns is less known. Nerve destruction leads to muscle atrophy. We posit that even mild burn injury could worsen demyelinated nerves related to muscle pathophysiological impairment. Methods: Young adult C57BL/6 (male, n = 60) mice were randomly fed with either a 0.2% cuprizone diet or a regular rodent diet for 4 weeks. At week 5, all mice were then grouped into mild scald burn with 10% TBSA and sham injury groups. Mice received animal behavior tests and in situ muscle isometric force measurement before euthanasia for tissue collection. Results: Total horizontal ambulation and vertical activity were significantly reduced in mice with mild burn injury (p<0.05). Mice with the cuprizone diet had significantly less time to fall than those with the regular diet on day 7 after burn (p<0.05). No significant difference was found in gastrocnemius tissue weight among the groups, nor muscle isometric tensions (all p>0.05). The cuprizone diet increased the maximal phosphorylating respiration in mice muscle mitochondria (p<0.05). The muscle protein expressions of caspase 3, Fbx-32, and Murf1 significantly increased in mice with the cuprizone diet 3 days after burn (p<0.05). The signal expression of S100B significantly increased in mice with the cuprizone diet, and its expression was even greater on day 7 after burn injury. (p<0.05) Conclusion: The cuprizone diet-induced locomotion and cognitive disorders were amplified by the mild burn injury in mice, which is associated with muscle intracellular signal alterations. However, mild burn injury does not cause mouse muscle weight loss and function impairment. The potential risk of pre-existed neural impairment could be aware when patients encounter even small or mild burns. [ABSTRACT FROM AUTHOR]

Key points Prolonged passive heat treatment (PHT) has been suggested to trigger skeletal muscle adaptations that may improve muscle maintenance in older individuals. To assess the effects of PHT on skeletal muscle tissue capillarization, perfusion capacity, protein synthesis rates, hypertrophy and leg strength, 14 older adults (9 males, 5 females; 73 ± 6 years) underwent 8 weeks of PHT (infrared sauna: 3× per week, 45 min at ∼60°C). Before and after PHT we collected muscle biopsies to assess skeletal muscle capillarization and fibre cross‐sectional area (CSA). Basal and postprandial muscle tissue perfusion kinetics and protein synthesis rates were assessed using contrast‐enhanced ultrasound and primed continuous l‐[ring‐13C6]phenylalanine infusions, respectively. One‐repetition maximum (1RM) leg strength and vastus lateralis muscle CSA were assessed. Type I and type II muscle fibre capillarization strongly increased following PHT (capillary‐to‐fibre perimeter exchange index: +31 ± 18 and +33 ± 30%, respectively; P < 0.001). No changes were observed in basal (0.24 ± 0.27 vs. 0.18 ± 0.11 AU; P = 0.266) or postprandial (0.20 ± 0.12 vs. 0.18 ± 0.14 AU; P = 0.717) microvascular blood flow following PHT. Basal (0.048 ± 0.014 vs. 0.051 ± 0.019%/h; P = 0.630) and postprandial (0.041 ± 0.012 vs. 0.051 ± 0.024%/h; P = 0.199) muscle protein synthesis rates did not change in response to prolonged PHT. Furthermore, no changes in vastus lateralis muscle CSA (15.3 ± 4.6 vs. 15.2 ± 4.6 cm2; P = 0.768) or 1RM leg strength (46 ± 12 vs. 47 ± 12 kg; P = 0.087) were observed over time. In conclusion, prolonged PHT increases muscle tissue capillarization but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates in healthy, older adults. Prolonged PHT does not induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. Repeated exposure to heat has been suggested to trigger skeletal muscle adaptive responses. We investigated the effect of 8 weeks of whole‐body passive heat treatment (PHT; infrared sauna: 3× per week for 45 min at ∼60°C) on skeletal muscle tissue capillarization, perfusion capacity, basal, and postprandial muscle protein synthesis rates, muscle (fibre) hypertrophy, and leg strength in healthy, older adults. Prolonged PHT increases muscle tissue capillarization, but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates. Despite increases in muscle tissue capillarization, prolonged PHT does not suffice to induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. [ABSTRACT FROM AUTHOR]

Aims and Objectives: This study aimed to investigate the effects of Umbilical Cord Mesencymal Stem Cell Conditioning Medium (UC MSC-CM) administration on body weight recovery and the level of four molecular biomarkers, namely Superoxide Dismutase (SOD), vascular Endothelial Growth Factor (VEGF), C-Reactive Protein (CRP), and myostatin. Materials and Methods: Secretome was injected intramuscularly twice at 1.5 mL (day 7 and 14) into the right thigh of high-dose, short-term galactose-induced aging rats. The data of day 7 (before) and day 21 (after the administration) were evaluated. The body weights and the four biomarkers were measured before (day 7) and after intervention (day 21). Results: This study showed that the UC MSC-CM intramuscular administrations did not influence body weight regeneration. However, it could increase SOD and VEGF levels and decrease CRP and myostatin levels. Conclusion: Treatment with UC MSC-CM is a promising and potential agent in treating sarcopenia. [ABSTRACT FROM AUTHOR]

AIM: To investigate the role of proviral integration site for Moloney murine leukemia virus 1 （PIM1） in the phenotypic switching of vascular smooth muscle cells （VSMCs） induced by oxidized low-density lipoprotein （oxLDL）, and to explore the underlying mechanisms. METHODS: Eighteen male ApoE-/- mice （8 weeks old） were randomly divided into general diet group and high-fat diet group, with 9 mice per group. After 16 weeks, aortic samples were analyzed using HE staining to observe plaque formation. In vitro, VSMCs were exposed to oxLDL to induce phenotypic transformation. Western blot and immunofluorescence were used to measure the protein expression levels of PIM1 and phenotypic markers including α-smooth muscle actin （α-SMA）, smooth muscle protein 22α （SM22α）, osteopontin （OPN）, and CD68. Glycolysis levels were assessed by detecting the expression of glycolytic enzymes 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase （PFKFB3） and hexokinase 2 （HK2） by Western blot, and lactate secretion was measured using a lactate test kit. The effects of SMI-4a（ a specific inhibitor of PIM1） and PIM1 small interfering RNA on oxLDL-induced phenotypic markers in VSMCs were evaluated. Moreover, the impact of 3-（3-pyridinyl）-1-（4-pyridinyl）-2-propen-1-one （3PO; a glycolysis inhibitor） on oxLDL-induced phenotypic switching and glycolysis in VSMCs was investigated. RESULTS: HE staining revealed atherosclerotic plaque formation in the aortas of ApoE-/- mice fed with high-fat diet. Immunofluorescence showed high accumulation of PIM1 and OPN in the tunica intima of atherosclerotic plaques. Compared with control group, aortic plaques exhibited significantly elevated levels of PIM1, OPN and CD68 proteins（ P<0. 01）, accompanied by reduced expression of contractile phenotype markers α-SMA and SM22α （P<0. 01）. In vitro, oxLDL treatment led to gradual decrease in α-SMA and SM22α expression（ P<0. 05 or P<0. 01）, while OPN and CD68 expression increased （P<0. 05 or P<0. 01）. Moreover, oxLDL significantly up-regulated the protein expression of PIM1, PFKFB3 and HK2, and increased lactate secretion in VSMCs （P<0. 05 or P<0. 01）. Knockdown of PIM1 or treatment with SMI-4a markedly attenuated these oxLDL-induced effects on VSMCs（ P<0. 05 or P<0. 01）. Treatment with 3PO also abolished oxLDL-induced phenotypic transformation and glycolysis in VSMCs （P<0. 05 or P<0. 01）. CONCLUSION: PIM1 highly accumulates in the atherosclerotic plaques of ApoE-/- mice. The phenotypic transformation of VSMCs was correlated with the expression of PIM1. PIM1 can regulate the phenotypic transformation of oxLDL-treated VSMCs by inducing glycolysis. [ABSTRACT FROM AUTHOR]

Using produced polyclonal antibodies specific to the N-terminal sequence (residues 61-298) of rat obscurin, we investigated the isoform composition of this protein in 4 striated muscles: myocardium of the left ventricle, diaphragm, skeletal m. gastrocnemius (containing mainly fast fibers), and m. soleus (containing mainly slow fibers). The m. gastrocnemius, m. soleus, and diaphragm were found to have 2 giant isoforms of obscurin: a smaller A-isoform and a larger B-isoform. Their molecular weights were ~870 and ~1150 kDa in the diaphragm and m. gastrocnemius and ~880 and ~1130 kDa in m. soleus, respectively. The B-isoform to A-isoform ratio was 1:3 in the diaphragm and m. soleus and 1:4 in the m. gastrocnemius. In the left-ventricular myocardium, A-isoform of obscurin with a molecular weight of ~880 kDa was found. No other obscurin isoforms or their fragments within the molecular weight range of 10 up to ~800 kDa were revealed in the investigated rat striated muscles. The antibodies produced are recommended for research into qualitative and quantitative changes of giant obscurin isoforms in rat striated muscles in the norm and during the development of pathological processes. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate whether flow fluid shear stress (FFSS)‐mediated signal transduction affects the function of Piezo1 ion channel in chondrocyte and to further explore the role of mechanical overloading in development of temporomandibular joint osteoarthritis (TMJ OA). Methods: Immunohistochemical staining was used to determine the expression of Piezo1 in TMJ OA tissue collected from rat unilateral anterior crossbite (UAC) models. Chondrocytes harvested from normal adult SD rats were treated with FFSS (0, 4, 8, 12 dyn/cm2) in vitro. Immunofluorescent staining, real‐time polymerase chain reaction, western blotting, flow cytometry and phalloidin assay were performed to detect the changes of cellular morphology as well as the expression of Piezo1 and certain pro‐inflammatory and degradative factors in chondrocyte. Results: Immunohistochemical analysis revealed that significantly increased Piezo1 expression was associated with UAC stimulation (p <.05). As applied FFSS escalated (4, 8 and 12 dyn/cm2), the expression levels of Piezo1, ADAMTS‐5, MMP‐13 and Col‐X gradually increased, compared with the non‐FFSS group (p <.05). Administering Piezo1 ion channel inhibitor to chondrocytes beforehand, it was observed that expression of ADAMTS‐5, MMP‐13 and Col‐X was substantially decreased following FFSS treatment (p <.05) and the effect of cytoskeletal thinning was counteracted. The activated Piezo1 ion channel enhanced intracellular Ca2+ excess in chondrocytes during abnormal mechanical stimulation and the increased intracellular Ca2+ thinned the cytoskeleton of F‐actin. Conclusions: Mechanical overloading activates Piezo1 ion channel to promote pro‐inflammation and degradation and to increase Ca2+ concentration in chondrocyte, which may eventually result in TMJ OA. [ABSTRACT FROM AUTHOR]

Sarcopenia is characterized by a decline in muscle strength, generalized loss of skeletal muscle mass, and impaired physical performance, which are common outcomes used to screen, diagnose, and determine severity of sarcopenia in older adults. These outcomes are associated with poor quality of life, increased risk of falls, hospitalization, and mortality in this population. The development of sarcopenia is underpinned by aging, but other factors can lead to sarcopenia, such as chronic diseases, physical inactivity, inadequate dietary energy intake, and reduced protein intake (nutrition‐related sarcopenia), leading to an imbalance between muscle protein synthesis and muscle protein breakdown. Protein digestion and absorption are also modified with age, as well as the reduced capacity of metabolizing protein, hindering older adults from achieving ideal protein consumption (i.e., 1–1.5 g/kg/day). Nutritional supplement strategies, like animal (i.e., whey protein) and plant‐based protein, leucine, and creatine have been shown to play a significant role in improving outcomes related to sarcopenia. However, the impact of other supplements (e.g., branched‐chain amino acids, isolated amino acids, and omega‐3) on sarcopenia and related outcomes remain unclear. This narrative review will discuss the evidence of the impact of these nutritional strategies on sarcopenia outcomes in older adults. [ABSTRACT FROM AUTHOR]

Simple Summary: The eating quality of fish is considered best when the durations between the slaughter, cooking, and consumption of the fish are minimized. Such a perception has raised animal welfare issues, as fish are captured, potentially under stress, before slaughter. In this study, it was revealed that with proper storage handling (in an ice box; ratio of fish to ice = 1:1; 2 h ice refills), the epaxial muscle samples of Asian seabass, one of the most economically important fish species, collected 24 h postmortem exhibited a greater degree of water-holding capacity and a more tender texture than 1 h postmortem samples. Free amino acids related to umami and sweetness were increased in the cooked samples collected 24 h postmortem. At 24 h postmortem, although the structural proteins of the epaxial muscles of Asian seabass remained intact, the myofibrils had undergone fragmentation to a greater extent, corresponding to meat tenderization without negative impacts on the springiness and cohesiveness of the cooked meat. The aim of this study was to compare the changes in the epaxial muscle proteins of Asian seabass at two different postmortem durations. The epaxial muscles of Asian seabass were collected 1 h or 24 h postmortem (PM). Whole, ungutted fish were stored in an ice box, with the ice refilled every two hours. The results show significant increases in the MFI values and the contents of solubilized sarcoplasmic proteins, with a molecular weight of proteins of 47 kDa in the 24 h PM samples (p < 0.05). Myofibrillar and alkaline-soluble proteins in the epaxial muscle remained intact 24 h postmortem. Compared with the 1 h PM samples, the 24 h PM meat exhibited lower degrees of expressible water and hardness (p < 0.05), indicating superior water-holding capacity and meat tenderness. However, no differences in springiness or cohesiveness of the cooked meat were observed. Free L-glutamic acid, known as an umami-tasting amino acid, was significantly increased upon the extension of postmortem duration, and its level was above the taste threshold concentration. Overall, the findings indicated that the 24 h PM epaxial muscle of Asian seabass exhibited superior technological properties, along with higher contents of taste-related amino acids. [ABSTRACT FROM AUTHOR]

Proteolytic products are extensively used in the nutraceutical sector to improve protein digestion and muscle quality in target populations (e.g., athletes or elderly). These products are processed using techniques that often lead to low purity but competitive pricing. Despite their widespread use and well-established production methods, the industry lacks standardized analytical methods for assessing these products and detecting potential fraud. This study proposes a comprehensive and harmonized pipeline for their analysis, which includes quantifying total soluble protein and proteolytic activity, as well as the determination of product stability and protein profile using SDS-PAGE and proteomic techniques. Despite the fact that protease extracts from pineapple had the highest protein content, most of the bromelain remained inactive, unlike in kiwi and papaya. SDS-PAGE revealed partial protein degradation of pineapple extracts, whereas kiwi extracts reflected a lower purification level but a higher protein integrity. The application of proteomic approaches strengthened the identification and origin tracing of the proteases. This study contributes to the development of a robust framework for analyzing proteolytic extracts, spanning from soluble protein quantification to protein profiling and activity determination. It may also ensure reliable supplier selection, high-quality manufacturing practices, and the implementation of optimal storage and formulation strategies in the nutraceutical industry. [ABSTRACT FROM AUTHOR]

Several observational and experimental studies in humans have suggested that high protein intake (PI) causes intraglomerular hypertension leading to hyperfiltration. This phenomenon results in progressive loss of renal function with long-term exposure to high-protein diets (HPDs), even in healthy people. The recommended daily allowance for PI is 0.83 g/kg per day, which meets the protein requirement for approximately 98% of the population. A HPD is defined as a protein consumption > 1.5 g/kg per day. Athletes and bodybuilders are encouraged to follow HPDs to optimize muscle protein balance, increase lean body mass, and enhance performance. A series of studies in resistance-trained athletes looking at HPD has been published concluding that there are no harmful effects of HPD on renal health. However, the aim of these studies was to evaluate body composition changes and they were not designed to assess safety or kidney outcomes. Here we review the effects of HPD on kidney health in athletes and healthy individuals with normal kidney function. [ABSTRACT FROM AUTHOR]

Precise regulation of sarcomeric contraction is essential for normal cardiac function. The heart must generate sufficient force to pump blood throughout the body, but either inadequate or excessive force can lead to dysregulation and disease. Myosin regulatory light chain (RLC) is a thick‐filament protein that binds to the neck of the myosin heavy chain. Post‐translational phosphorylation of RLC (RLC‐P) by myosin light chain kinase is known to influence acto‐myosin interactions, thereby increasing force production and Ca2+‐sensitivity of contraction. Here, we investigated the role of RLC‐P on cardiac structure and function as sarcomere length and [Ca2+] were altered. We found that at low, non‐activating levels of Ca2+, RLC‐P contributed to myosin head disorder, though there were no effects on isometric stress production and viscoelastic stiffness. With increases in sarcomere length and Ca2+‐activation, the structural changes due to RLC‐P become greater, which translates into greater force production, greater viscoelastic stiffness, slowed myosin detachment rates and altered nucleotide handling. Altogether, these data suggest that RLC‐P may alter thick‐filament structure by releasing ordered, off‐state myosin. These more disordered myosin heads are available to bind actin, which could result in greater force production as Ca2+ levels increase. However, prolonged cross‐bridge attachment duration due to slower ADP release could delay relaxation long enough to enable cross‐bridge rebinding. Together, this work further elucidates the effects of RLC‐P in regulating muscle function, thereby promoting a better understanding of thick‐filament regulatory contributions to cardiac function in health and disease. Key points: Myosin regulatory light chain (RLC) is a thick‐filament protein in the cardiac sarcomere that can be phosphorylated (RLC‐P), and changes in RLC‐P are associated with cardiac dysfunction and disease.This study assesses how RLC‐P alters cardiac muscle structure and function at different sarcomere lengths and calcium concentrations.At low, non‐activating levels of Ca2+, RLC‐P contributed to myofilament disorder, though there were no effects on isometric stress production and viscoelastic stiffness.With increases in sarcomere length and Ca2+‐activation, the structural changes due to RLC‐P become greater, which translates into greater force production, greater viscoelastic stiffness, slower myosin detachment rate and altered cross‐bridge nucleotide handling rates.This work elucidates the role of RLC‐P in regulating muscle function and facilitates understanding of thick‐filament regulatory protein contributions to cardiac function in health and disease. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy (DN) is one of microvascular complication associated with diabetes. Circular RNAs (circRNAs) have been shown to be involved in DN pathogenesis. Hence, this work aimed to explore the role and mechanism of circ_Arf3 in DN. Mouse mesangial cells (MCs) cultured in high glucose (HG) condition were used for functional analysis. Cell proliferation was determined using 5-ethynyl-2'-deoxyuridine (EdU) and cell counting kit-8 assays. Western blotting was used to measure the levels of proliferation indicator PCNA and fibrosis-related proteins α-smooth muscle actin (α-SMA), collagen I (Col I), fibronectin (FN), and collagen IV (Col IV). The binding interaction between miR-107-3p and circ_Arf3 or Tmbim6 (transmembrane BAX inhibitor motif containing 6) was confirmed using dual-luciferase reporter and pull-down assays. Circ_Arf3 is a stable circRNA, and the expression of circ_Arf3 was decreased after HG treatment in MCs. Functionally, ectopic overexpression of circ_Arf3 protected against HG-induced proliferation and elevation of fibrosis-related proteins in MCs. Mechanistically, circ_Arf3 directly bound to miR-107-3p, and Tmbim6 was a target of miR-107-3p. Further rescue assay showed miR-107-3p reversed the protective action of circ_Arf3 on MCs function under HG condition. Moreover, inhibition of miR-107-3p suppressed HG-induced proliferation and fibrosis, which were attenuated by Tmbim6 knockdown in MCs. CircRNA Arf3 could suppress HG-evoked mesangial cell proliferation and fibrosis via miR-107-3p/Tmbim6 axis, indicating the potential involvement of this axis in DN progression. Highlight: Circ_Arf3 expression was decreased after HG treatment in MCs. Ectopic overexpression of circ_Arf3 suppresses MC proliferation and fibrosis under HG condition. Circ_Arf3 can indirectly regulate Tmbim6 expression via sponging miR-107-3p. The miR-107-3p/Tmbim6 axis mediates the protective effects of circ_Arf3 on MC function in the presence of HG. [ABSTRACT FROM AUTHOR]

Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway. What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K. What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training. [ABSTRACT FROM AUTHOR]

After an initial increase, isovelocity elongation of a muscle fiber can lead to diminishing (referred to as Give in the literature) and subsequently increasing force. How the stretch velocity affects this behavior in slow-twitch fibers remains largely unexplored. Here, we stretched fully activated individual rat soleus muscle fibers from 0.85 to 1.3 optimal fiber length at stretch velocities of 0.01, 0.1, and 1 maximum shortening velocity, vmax, and compared the results with those of rat EDL fast-twitch fibers obtained in similar experimental conditions. In soleus muscle fibers, Give was 7%, 18%, and 44% of maximum isometric force for 0.01, 0.1, and 1 vmax, respectively. As in EDL fibers, the force increased nearly linearly in the second half of the stretch, although the number of crossbridges decreased, and its slope increased with stretch velocity. Our findings are consistent with the concept of a forceful detachment and subsequent crossbridge reattachment in the stretch's first phase and a strong viscoelastic titin contribution to fiber force in the second phase of the stretch. Interestingly, we found interaction effects of stretch velocity and fiber type on force parameters in both stretch phases, hinting at fiber type-specific differences in crossbridge and titin contributions to eccentric force. Whether fiber type-specific combined XB and non-XB models can explain these effects or if they hint at some not fully understood properties of muscle contraction remains to be shown. These results may stimulate new optimization perspectives in sports training and provide a better understanding of structure–function relations of muscle proteins. [ABSTRACT FROM AUTHOR]

3-Methylhistidine (3-MeHis) is increasingly used as an indicator of muscle protein breakdown. The development of a sensitive, simple, and non-invasive method for 3-MeHis assay is important in clinical practice. Herein, a sensitive, simple, and non-invasive electrogenerated chemiluminescence (ECL) method was proposed for the quantitation of 3-MeHis in urine by using an iridium(III) solvent complex ([Ir(dfppy)2(DMSO)Cl], dfppy = 2-(2,4-difluorophenyl)pyridine, Ir-DMSO) as a signal reagent. The photoluminescence (PL) and ECL responses of Ir-DMSO to 3-MeHis were studied. The ECL intensity of Ir-DMSO was enhanced in the presence of 3-MeHis because of the coordination recognition between Ir-DMSO and the imidazole group of 3-MeHis. Based on the enhancement of ECL intensity, 3-MeHis can be sensitively detected in the range of 5 to 25 μM. The detection limit was 0.4 μM. This is the first report of an ECL method for the quantitation of 3-MeHis. Further, to investigate the feasibility of the Ir-DMSO-based ECL method in practical applications, the developed ECL method was applied for 3-MeHis assay in urine samples of 28 healthy volunteers and 2 patients. The urine samples from patients hospitalized with obesity and kidney disease and healthy individuals were distinguished by the ECL responses of Ir-DMSO. The proposed ECL method based on the coordination recognition between iridium(III) solvent complex and the imidazole group of 3-MeHis allows inexpensive, fast, non-invasive, and sensitive detection of 3-MeHis in urine, which is promising for assessing large volumes of patients for routine analysis in clinical practices. [ABSTRACT FROM AUTHOR]

Dietary protein plays a crucial role in the modulation of several physiological processes to sustain health and well‐being. There is robust evidence of enhanced muscle protein synthesis, improved physical fitness, body composition, and performance contributed by protein supplementation combined with exercise among trained individuals or athletes. Evidence of the efficacy of such intervention on healthy adults having a sedentary lifestyle is limited. The objective of this study was to evaluate the impact of 12 g of additional protein in the form of a protein supplement compared to a placebo combined with a simple exercise program on plasma amino acid level, body composition, and muscle strength among healthy Indian adults having a relatively sedentary lifestyle. This double‐blinded, randomized controlled trial was conducted on sedentary healthy adults 20–45 years of age, with a body mass index (BMI) between 18.5 and 27.9 kg/m2. Eighty‐two participants were randomized into either the protein (intervention) or placebo (control) group. The exercise regime was the same for both groups. Out of 82 randomized participants, 58 completed the intervention. Blood tests were conducted for the amino acid OMICS measurement followed by dual‐energy X‐ray absorptiometry (DXA) for body composition and isokinetic dynamometry for muscle strength. A significant improvement was observed in the lean mass (kg) and appendicular muscle mass (AMM) adjusted for weight in the intervention group compared to the control group (p < 0.05). The muscle strength and contractile quality were comparable in the 2 groups. Plasma BCAA showed a significant negative association with body fat % (r = −0.43, p < 0.05 for the intervention group and r = −0.33, p = 0.07 for the control group) and a positive association with lean body mass % (r = 0.56, p < 0.01 in the intervention group vs r = 0.29, p = 0.10 in the control group) in the intervention group compared to control. In conclusion, this study highlighted the value of incorporating a lifestyle intervention including protein supplementation with simple exercises to optimize body composition in sedentary healthy individuals. This trial is registered with CTRI/2018/12/016777. [ABSTRACT FROM AUTHOR]

【Objective】In the early stage of the study, the high-efficient and low-fishmeal compound feed developed by our research group showed good application effects in the aquaculture of small-sized Trachinotus ovatus. The study was conducted to further evaluate the application effect of this feed in the aquaculture of large-sized T. ovatus, to provide some references for practical production.【Method】Based on the formula of commercial feed (CK) and high-efficient and low-fishmeal compound feed (test feed), two groups of feed were prepared by feed processing technology and equipment of the enterprise, and large-sized Trachinotus ovatus (125.8 ± 0.70 g) were fed for 95 d. The growth performance, serum biochemical indicators, digestive enzyme activity and muscle quality of each group were compared and analyzed.【Result】There was no significant difference in the growth performance, morphological indicators, serum and liver antioxidant performance indicators, and intestinal digestive enzyme activities between the two groups (P > 0.05). However, the daily feed intake, specific growth rate, daily weight gain rate and weight gain rate of the test group T. ovatus were 2.64%, 1.35%, 2.73%, 247.34%, which were 0.21, 0.03, 0.07, 2.25 percentage point higher than those of the control group, respectively, while the feed coefficient that was 0.03 percentage point lower. The levels of total cholesterol (T-CHO), serum triglyceride(TG), low-density lipoprotein cholesterol(LDL-C) in the test group were 0.88, 0.18, 0.30 mmol/L, which were significantly reduced when compared with the control group, while the HDL-C/LDL-C ratio (102.20%) was significantly increased (P < 0.05). In terms of muscle quality, there was no significant difference in muscle protein and fat content as well as amino acid composition (total amino acids, essential amino acids and flavor amino acids) between the two groups (P > 0.05). However, the test feed significantly improved the texture characteristics of the muscle and increased the EPA level in the muscle. Furthermore, compared with the commercial feed, the cost of the test feed was reduced by 8.65%, and the aquaculture benefit was increased by 17.76%.【Conclusion】In the aquaculture of large-sized T. ovatus, the high-efficient and low-fishmeal compound feed exhibits similar growth-promoting effects as commercial feed, and it helps to reduce blood lipids, lower aquaculture costs, and improve aquaculture benefits. The above results indicate that the high-efficient and low-fishmeal compound feed can be applied in the entire aquaculture cycle of T. ovatus. [ABSTRACT FROM AUTHOR]

The intermuscular bones of fish are closely related to their locomotion; the more athletic the fish is, the greater the number of intermuscular bones and the relatively higher the muscle fat content. In order to investigate whether C. brachygnathus exists migratory ecological taxa in Poyang Lake, samples of C. brachygnathus were collected from different sampling sites of Poyang Lake, such as Qianyanqiao. In addition, samples of C. nasus from Zhoushan Shengsi and Qingcaosha Reservoir at the mouth of the Yangtze River were collected in order to investigate the effect of migration on the formation of intermuscular bones of C. nasus. The morphology, number and muscle protein and fat content of medullary arch ossicles and pulse arch ossicles were compared by anatomical method and conventional measurement method. The results showed that： (1) The number of intermuscular bones of C. brachygnathus was the least in the Poyang Lake which was 100.67±6.34; The number of intermuscular bones in Qianyanqiao was the largest which was 127.67±6.18. (2)The intermuscular bone number of C.nasus in Poyang Lake was 129.60±0.98 which was significantly higher than C. brachygnathus of 110.60±2.97. (3) The number of Poyanghu intermuscular bones of the same species was significantly higher than that of 113.67±3.29 intermuscular bones of the Qingcaosha but lower than that of 147.67±3.09 intermuscular bones of Shengsi ; (4) The protein content of muscle in the C.nasus in Poyang Lake was lower than that of the C. brachygnathus, and the fat content was higher than that of the C.brachygnathus. Suggesting that the C.nasus need to oscillate more in order to fulfil the needs of long-distance migration and to stimulate more intermuscular spine formation. These results are important for the understanding of the difference in the origin of the migratory populations of C. nasus and C. brachygnathus in Poyang Lake, and lay the foundation for the further research on the biology of the migratory populations in Poyang Lake. [ABSTRACT FROM AUTHOR]

CCDC78 was identified as a novel candidate gene for autosomal dominant centronuclear myopathy-4 (CNM4) approximately ten years ago. However, to date, only one family has been described, and the function of CCDC78 remains unclear. Here, we analyze for the first time a family harboring a CCDC78 nonsense mutation to better understand the role of CCDC78 in muscle. Methods: We conducted a comprehensive histopathological analysis on muscle biopsies, including immunofluorescent assays to detect multiple sarcoplasmic proteins. We examined CCDC78 transcripts and protein using WB in CCDC78-mutated muscle tissue; these analyses were also performed on muscle, lymphocytes, and fibroblasts from healthy subjects. Subsequently, we conducted RT-qPCR and transcriptome profiling through RNA-seq to evaluate changes in gene expression associated with CCDC78 dysfunction in muscle. Lastly, coimmunoprecipitation (Co-Ip) assays and mass spectrometry (LC-MS/MS) studies were carried out on extracted muscle proteins from both healthy and mutated subjects. Results: The histopathological features in muscle showed novel histological hallmarks, which included areas of dilated and swollen sarcoplasmic reticulum (SR). We provided evidence of nonsense-mediated mRNA decay (NMD), identified the presence of novel CCDC78 transcripts in muscle and lymphocytes, and identified 1035 muscular differentially expressed genes, including several involved in the SR. Through the Co-Ip assays and LC-MS/MS studies, we demonstrated that CCDC78 interacts with two key SR proteins: SERCA1 and CASQ1. We also observed interactions with MYH1, ACTN2, and ACTA1. Conclusions: Our findings provide insight, for the first time, into the interactors and possible role of CCDC78 in skeletal muscle, locating the protein in the SR. Furthermore, our data expand on the phenotype previously associated with CCDC78 mutations, indicating potential histopathological hallmarks of the disease in human muscle. Based on our data, we can consider CCDC78 as the causative gene for CNM4. [ABSTRACT FROM AUTHOR]

Simple Summary: Due to the underdeveloped digestive tracts of larval fish, predigested fish protein has been included in feeds to help increase dietary protein utilization. The predigested protein has been produced from various protein sources and broken down using different methods. This has ultimately led to variable results when included in larval diets, and there is still a lack of an optimal dry diet for larval fish. This study tested the use of adult Walleye muscle as a protein source to provide the optimal dietary amino acid composition for same-species larvae. The muscle was also broken down with enzymes from the adult Walleye gut to predigest protein in a way that mimics the digestion of live Walleye. This protein source was tested against protein produced from muscle and/or enzymes from Nile Tilapia, as a non-species-specific source. The dietary inclusion of predigested protein produced from same-species muscle and digestive enzymes led to increased growth and amino acid absorption in larval Walleye. However, reduced survival in fish fed with the predigested protein suggests that further research is required to improve the pellet stability of the larval diets and reduce the loss of nutrients to the water. Fish protein hydrolysates used in larval diets have been prepared from a variety of fish species, with different enzymes used to hydrolyze the protein. This study's objectives were to determine the effect of the dietary inclusion of fish muscle hydrolysates obtained from species-specific muscle/enzymes—versus hydrolysates produced from muscle/enzymes of a different species—on the growth performance, survival, skeletal development, intestinal peptide uptake, and muscle-free amino acid (FAA) composition of larval Walleye (Sander vitreus). Eight protein products were obtained for this study, comprising an unhydrolyzed and hydrolyzed product from each combination of muscle/enzymes from Walleye and Nile tilapia (Oreochromis niloticus). Four diets were produced, and the dietary protein was provided in a 50/50 ratio of unhydrolyzed and hydrolyzed protein from the respective muscle/enzyme combination. Four groups were fed one of the corresponding formulated diets, and two groups of larvae, fed a commercial starter diet and Artemia, respectively, served as reference groups. Larval Walleye fed the diet containing protein produced with the species-specific muscle and enzymes had a significantly higher weight after the study—30% higher than any other group. A significant interaction effect between muscle and enzyme sources on the growth of Walleye larvae was observed. The species-specific combination also led to a significant increase in postprandial FAA and indispensable amino acid concentrations in muscle. No significant differences were observed between the hydrolysate-fed groups in survival, deformity occurrence, or peptide uptake. Each hydrolysate-based diet significantly reduced skeletal deformities and survival compared to the commercial diet. The results of this study suggest that species-specific muscles and enzymes produce a more optimal dietary protein source for larval fish than non-species-specific products. Further research should focus on improving the physical properties of the formulated diets to reduce possible leaching of hydrolyzed protein and improve the survival of fish larvae. [ABSTRACT FROM AUTHOR]

The elongation of Caenorhabditis elegans embryos allows examination of mechanical interactions between adjacent tissues. Muscle contractions during late elongation induce the remodeling of epidermal circumferential actin filaments through mechanotransduction. Force inputs from the muscles deform circumferential epidermal actin filament, which causes them to be severed, eventually reformed, and shortened. This squeezing force drives embryonic elongation. We investigated the possible role of the nonmuscle myosins NMY-1 and NMY-2 in this process using nmy-1 and nmy-2 thermosensitive alleles. Our findings show these myosins act redundantly in late elongation, since double nmy-2(ts); nmy-1(ts) mutants immediately stop elongation when raised to 25°C. Their inactivation does not reduce muscle activity, as measured from epidermis deformation, suggesting that they are directly involved in the multistep process of epidermal remodeling. Furthermore, NMY-1 and NMY-2 inactivation is reversible when embryos are kept at the nonpermissive temperature for a few hours. However, after longer exposure to 25°C double mutant embryos fail to resume elongation, presumably because NMY-1 was seen to form protein aggregates. We propose that the two C. elegans nonmuscle myosin II act during actin remodeling either to bring severed ends or hold them. [ABSTRACT FROM AUTHOR]

Introduction: Lenvatinib and sorafenib are key therapeutic agents for hepatocellular carcinoma (HCC). However, there are no useful biomarkers for selecting molecular-targeted agents (MTAs). Skeletal muscle volume is associated with the clinical outcomes in these patients. We investigated the effects of lenvatinib and sorafenib on the skeletal muscles of patients with HCC. Methods: We evaluated the impact of skeletal muscle changes over a 3-month period for each MTA (n = 117; lenvatinib/sorafenib, 45/72). The skeletal muscle mass index (SMI) was measured at the third lumbar vertebra. Furthermore, we evaluated the direct effect of each MTA on primary human skeletal muscle cells by estimating muscle protein synthesis using western blot analysis. Results: The median change in SMI was −0.7% (p = 0.959) and −5.9% (p < 0.001) for the lenvatinib and sorafenib groups, respectively. Sorafenib had a greater effect on skeletal muscle loss than lenvatinib (p < 0.001). Additionally, SMI significantly decreased in the sorafenib group regardless of initial skeletal muscle volume (p < 0.001), whereas no significant differences were observed in the lenvatinib group. Sorafenib therapy (odds ratio [OR], 2.98; p = 0.023) and non-muscle depletion (OR, 3.31; p = 0.009) were associated with a decreased SMI. In vitro analysis showed that sorafenib negatively affected muscle synthesis compared to lenvatinib. Conclusions: Sorafenib may have a more negative effect on skeletal muscle than lenvatinib. [ABSTRACT FROM AUTHOR]

Small-angle X-ray scattering (SAXS) and Fourier transform infrared (FTIR) spectroscopy were used to investigate structural peculiarities of two types of amyloid aggregates of smooth muscle titin, which differed in their morphology and ability to disaggregate, and differently bound thioflavin T dye. SAXS showed that the structure/shape of the two titin aggregate types was close to a flat shape. FTIR spectroscopy revealed no differences in the secondary structure of the two types. These data suggest that both types of "flat-shape" titin aggregates are identical in their secondary structure and, as shown previously, have a quaternary cross-β structure. An assumption was made that the most stable supramolecular complexes of a cross-β structure, which do not differ in their secondary structure, formed first during the aggregation of smooth muscle titin. Then, depending on ambient conditions, these supramolecular structures could form titin aggregates of different morphology and properties. [ABSTRACT FROM AUTHOR]

Purpose: Whey protein ingestion is typically considered an optimal dietary strategy tomaximizemyofibrillar protein synthesis (MyoPS) after resistance exercise. Although single-source plant protein ingestion is typically less effective, at least partly, due to less favorable amino acid profiles, this could theoretically be overcome by blending plant-based proteins with complementary amino acid profiles. We compared the postexercise MyoPS response after the ingestion of a novel plant-derived protein blend with an isonitrogenous bolus of whey protein. Methods: Ten healthy, resistance-trained, young adults (male/female: 8/2; age: 26 ± 6 yr; BMI: 24 ± 3 kg·m-2) received a primed continuous infusion of L-[ring-²H5]-phenylalanine and completed a bout of bilateral leg resistance exercise before ingesting 32 g protein from whey (WHEY) or a plant protein blend (BLEND; 39.5% pea, 39.5% brown rice, 21.0% canola) in a randomized, double-blind crossover fashion. Blood and muscle samples were collected at rest, and 2 and 4 h after exercise and protein ingestion, to assess plasma amino acid concentrations, and postabsorptive and postexercise MyoPS rates. Results: Plasma essential amino acid availability over the 4 h postprandial postexercise period was ~44% higher inWHEY compared with BLEND (P = 0.04). From equivalent postabsorptive values (WHEY, 0.042 ± 0.020%·h-1; BLEND, 0.043 ± 0.015%·h-1) MyoPS rates increased after exercise and protein ingestion (time effect; P < 0.001) over a 0- to 2-h period (WHEY, 0.085 ± 0.037%·h-1; BLEND, 0.080 ± 0.037%·h-1) and 2- to 4-h period (WHEY, 0.085 ± 0.036%·h-1; BLEND, 0.086 ± 0.034%·h-1), with no differences between conditions during either period or throughout the entire (0-4 h) postprandial period (time-condition interactions; all P > 0.05). Conclusions: Ingestion of a novel plant-based protein blend stimulates postexercise MyoPS to an equivalent extent as whey protein, demonstrating the utility of plant protein blends to optimize postexercise skeletal muscle reconditioning. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the impact of a 5-wk sprint interval training (SIT) intervention on time to task failure (TTF) during severe-intensity constant work rate (CWR) exercise, as well as in glycolytic enzymatic content and activity, and glycogen content. Methods: Fourteen active males were randomized into either a SIT group (n = 8) composed of 15 SIT sessions over 5 wk, or a control group (n = 6). At pretraining period, participants performed i) ramp incremental test to measure the cardiorespiratory function; ii) CWR cycling TTF at 150%of the power output (PO) at the respiratory compensation point (RCP-PO) with muscle biopsies at rest and immediately following task failure. After 5 wk, the same evaluations were repeated (i.e., exercise intensities matched to current training status), and an additional cycling CWR matched to pretraining 150% RCP-PO was performed only for TTF evaluation. The content and enzymatic activity of glycogen phosphorylase (GPhos), hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH), as well as the glycogen content, were analyzed. Content ofmonocarboxylate transporter isoform 4 (MCT4) and muscle buffering capacity were also measured. Results: Despite improvements in total work performed at CWR posttraining, no differences were observed for TTF. The GPhos, HK, PFK, and LDHcontent and activity, and glycogen content also improved after training only in the SIT group. Furthermore, theMCT4 concentrations andmuscle buffering capacitywere also improved only for the SIT group. However, no difference in glycogen depletion was observed between groups and time. Conclusions: Five weeks of SIT improved the glycolytic pathway parameters and total work performed; however, glycogen depletion was not altered during CWR severe-intensity exercise, and TTF remained similar. [ABSTRACT FROM AUTHOR]

To survive daily damage, the formation of actomyosin ring at the wound edge is required to rapidly close cell wounds. Calcium influx is one of the start signals for these cell wound repair events. Here, we find that the rapid recruitment of all 3 Drosophila calcium-responding and phospholipid-binding Annexin proteins (AnxB9, AnxB10, and AnxB11) to distinct regions around the wound is regulated by the quantity of calcium influx rather than their binding to specific phospholipids. The distinct recruitment patterns of these Annexins regulate the subsequent recruitment of RhoGEF2 and RhoGEF3 through actin stabilization to form a robust actomyosin ring. Surprisingly, while the wound does not close in the absence of calcium influx, we find that reduced calcium influx can still initiate repair processes, albeit leading to severe repair phenotypes. Thus, our results suggest that, in addition to initiating repair events, the quantity of calcium influx is important for precise Annexin spatiotemporal protein recruitment to cell wounds and efficient wound repair. [ABSTRACT FROM AUTHOR]

Insulin resistance (IR) is a risk factor for the development of several major metabolic diseases. Muscle fiber composition is established early in life and is associated with insulin sensitivity. Hence, muscle fiber composition was used to identify early defects in the development of IR in healthy young individuals in the absence of clinical manifestations. Biopsies were obtained from the thigh muscle, followed by an intravenous glucose tolerance test. Indices of insulin action were calculated and cardiovascular measurements, analyses of blood and muscle were performed. Whole body insulin sensitivity (SIgalvin) was positively related to expression of type I muscle fibers (r = 0.49; P < 0.001) and negatively related to resting heart rate (HR, r = −0.39; P < 0.001), which was also negatively related to expression of type I muscle fibers (r = −0.41; P < 0.001). Muscle protein expression of endothelial nitric oxide synthase (eNOS), whose activation results in vasodilation, was measured in two subsets of subjects expressing a high percentage of type I fibers (59 ± 6%; HR = 57 ± 9 beats/min; SIgalvin = 1.8 ± 0.7 units) or low percentage of type I fibers (30 ± 6%; HR = 71 ± 11; SIgalvin = 0.8 ± 0.3 units; P < 0.001 for all variables vs. first group). eNOS expression was 1) higher in subjects with high type I expression; 2) almost twofold higher in pools of type I versus II fibers; 3) only detected in capillaries surrounding muscle fibers; and 4) linearly associated with SIgalvin. These data demonstrate that an altered function of the autonomic nervous system and a compromised capacity for vasodilation in the microvasculature occur early in the development of IR. NEW & NOTEWORTHY: Insulin resistance (IR) is a risk factor for the development of several metabolic diseases. In healthy young individuals, an elevated heart rate (HR) correlates with low insulin sensitivity and high expression of type II skeletal muscle fibers, which express low levels of endothelial nitric oxide synthase (eNOS) and, hence, a limited capacity to induce vasodilation in response to insulin. Early targeting of the autonomic nervous system and microvasculature may attenuate development of diseases stemming from insulin resistance. [ABSTRACT FROM AUTHOR]

Background and aims: PKC‐fused blue naevi are a recently described group of melanocytic tumours that have distinctive morphological features, including a pigmented epithelioid melanocytoma‐like junctional component or a dermal biphasic architecture associating with naevocytoid nests surrounded by dendritic and spindled pigmented melanocytes (so‐called 'combined common and blue naevus'). There have been reports of smooth muscle hyperplasia in a hamartoma‐like pattern in cases of combined blue naevi without genetic exploration. Materials and methods: Herein, we describe 12 cases of protein kinase C (PKC)‐fused blue tumours associated with a co‐existing smooth muscle hyperplasia, identified from a total of 98 PKC‐fused melanocytic tumours. Archived slides of PKC‐fused blue naevi with haematoxylin, eosin and phloxin staining, immunohistochemistry and molecular confirmation of a PKC‐fusion by fluorescence in‐situ hybridisation (FISH) or RNAseq were re‐evaluated for identification of notable smooth muscle hyperplasia. Fifty‐one of these slides had already been studied in a previous publication from our group. Results: The hyperplasia ranged from hypertrophic arrector pili muscles to extensive horizontal bundles of disorganised fibres constantly associated and limited within a biphasic dermal melanocytic component. At least one arrector pili muscle was always visible within the tumour, with occasionally direct extension of the hyperplastic fibres from the main muscle body. These muscle fibres were devoid of a PKC‐fusion signal by FISH. PKC molecules are involved in the regulation of smooth muscle function, offering an explanatory framework. Conclusions: These data suggest incorporating smooth muscle hyperplasia as a diagnostic morphological feature of PKC‐fused blue melanocytic tumours. [ABSTRACT FROM AUTHOR]