Search Results (206)

Laboratory-based assessment of cardiorespiratory function is a widely applied method in sports science. Most performance evaluations focus on oxygen uptake parameters. Despite the well-established concept of oxygen deficit introduced by Hill in the 1920s, relatively few studies have examined its behavior during submaximal exercise, with limited exploration of deficit dynamics. The present study aimed to analyze the behavior of oxygen deficit in young female handball players (N = 42, age: 15.4 ± 1.3 years) during graded exercise. Oxygen deficit was estimated using the American College of Sports Medicine (ACSM) algorithm, restricted to subanaerobic threshold segments of a quasi-ramp exercise protocol. Cardiorespiratory parameters were measured with the spiroergometry test on treadmills, and body composition was assessed via Dual Energy X-ray Absorptiometry (DEXA). Cluster and principal component analyzes revealed two distinct athlete profiles with statistically significant differences in both morphological and physiological traits. Cluster 2 showed significantly higher relative VO₂ peak (51.43 ± 3.70 vs. 45.70 ± 2.87 mL·kg⁻¹·min⁻¹; p < 0.001; Cohen’s d = 1.76), yet also exhibited a greater oxygen deficit per kilogram (39.03 ± 16.71 vs. 32.56 ± 14.33 mL·kg⁻¹; p = 0.018; d = 0.80). Cluster 1 had higher absolute body mass (69.67 ± 8.13 vs. 59.66 ± 6.81 kg; p < 0.001), skeletal muscle mass (p < 0.001), and fat mass (p < 0.001), indicating that body composition strongly influenced oxygen deficit values. The observed differences in oxygen deficit profiles suggest a strong influence of genetic predispositions, particularly in cardiovascular and muscular oxygen utilization capacity. Age also emerged as a critical factor in determining the potential for adaptation. Oxygen deficit during submaximal exercise appears to be a multifactorial phenomenon shaped by structural and physiological traits. While certain influencing factors can be modified through training, others especially those of genetic origin pose inherent limitations. Early development of cardiorespiratory capacity may offer the most effective strategy for long-term optimization. Full article

The postmortem interval (PMI), defined as the time elapsed between death and the discovery or examination of the body, is a crucial parameter in forensic science for estimating the time of death. There are many ways to measure the PMI, such as Henssge’s nomogram, which uses rectal temperature measurement; livor mortis; rigor mortis; and forensic entomology. However, these methods are usually affected by various conditions in the surrounding environment. The purpose of the present study was to compare molecular genetics and histological changes in the brain and skeletal muscle tissues of SD rats over increasing periods of time after death. For the PMIs, we considered 0 h, 6 h, 12 h, 24 h, 36 h, 48 h, 4 days, 6 days, 8 days, 10 days, 14 days, and 21 days and compared them at 4 °C and 26 °C. Hematoxylin and Eosin (H&E) staining was performed to observe tissue changes. Morphological tissue changes were observed in cells for up to 21 days at 4 °C, and cell destruction was visually confirmed after 14 days at 26 °C. Total RNA (tRNA) was isolated from each tissue sample, and complementary DNA (cDNA) was synthesized. A reverse transcription quantitative PCR (RT-qPCR) SYBR Green assay targeting three types of housekeeping genes, including Gapdh, Sort1, B2m, and 5S rRNA, was performed. The results showed that Gapdh and 5S rRNA were highly stable and could be better RNA targets for estimating the PMI in brain and skeletal muscle tissues. Conversely, Sort1 and B2m showed poor stability and low expression levels. In conclusion, these molecular biomarkers could be used as auxiliary indicators of the PMI in human, depending on the stability of the marker. Full article

The decline in differentiation capacity during skeletal muscle (SkM) aging contributes to the deterioration of skeletal muscle function and impairs regenerative ability. Epicatechin gallate (ECG), a major functional component of catechins found in tea, has an unclear role in aging-related sarcopenia. In vivo experiments in 54-week-old C57BL/6J mice showed that ECG treatment improved exercise performance, muscle mass, and fiber morphology and downregulated the expression of the testosterone metabolic enzyme gene UGT2A3 in aged mice. In vitro experiments with Leydig cells (TM3) demonstrated that ECG upregulated the mRNA and protein expression levels of testosterone synthase genes, including StAR, P450scc, 3β-HSD, CYP17a1, and 17β-HSD. Network pharmacology analysis further suggested that ECG can influence testosterone secretion through the regulation of cytokines, thereby promoting skeletal muscle differentiation. These findings indicate that ECG enhances the differentiation of skeletal muscle cells by modulating testosterone levels, which helps alleviate age-related muscle function decline. Full article

Efficient new methods are needed to support initiatives to reduce, refine, and/or replace toxicity testing in vertebrates. 5-fluorouracil (5FU), hydroxyurea (HU), and ribavirin (RV) are mammalian teratogens. Skeletal, endocrine organ, and cardiac effects are often associated with teratogenesis, and a simple nematode like C. elegans lacks these systems. However, many genetic pathways required for mammalian morphogenesis have at least some conserved elements in this small, invertebrate model. The C. elegans lifecycle is 3 days. The effects of 5FU, HU, and RV on the C. elegans morphology were evaluated on day 4 post-initiation of the feeding after hatching for continuous and 24 h (early-only) developmental exposures. Continuous exposures to 5FU and HU induced increases in the incidences of abnormal gonadal structures that were significantly reduced in early-only exposure groups. The incidence of prolapse increased with continuous 5FU and HU exposures and was further increased in early-only exposure groups. Intestinal prolapse through the vulval muscle in C. elegans may be related to reported 5FU and HU effects on skeletal muscle and the gastrointestinal tract in mammals. Continuous RV exposures induced a phenotype lacking a uterus and gonad arms, as well as vulval anomalies that were largely, but not completely, reversed with early-only exposures, which is consistent with reported reversible reproductive tract anomalies after an RV exposure in mammals. These findings suggest that C. elegans can be used to detect the hazard risk from chemicals that adversely affect conserved pathways involved in organismal morphogenesis, but to determine the fit-for-purpose use of this model in chemical safety evaluations, further studies using larger and more diverse chemical test panels are needed. Full article

Background/Objectives: Temporomandibular disorders (TMDs) are a group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles, and related anatomical structures. Although magnetic resonance imaging (MRI) is considered a noninvasive and highly informative imaging modality for assessing TMJ soft tissues, few studies have examined how TMJ structural features observed on MRI findings relate to oral function and craniofacial morphology in female patients with malocclusion. To investigate the associations among TMJ structural features, oral function, and craniofacial morphology in female patients with malocclusion, using MRI findings interpreted in conjunction with a preliminary assessment based on selected components of the DC/TMDs Axis I protocol. Methods: A total of 120 female patients (mean age: 27.3 ± 10.9 years) underwent clinical examination based on DC/TMDs Axis I and MRI-based structural characterization of the TMJ. Based on the structural features identified by MRI, patients were classified into four groups for comparison: osteoarthritis (OA), bilateral disk displacement (BDD), unilateral disk displacement (UDD), and a group with Osseous Change/Disk Displacement negative (OC/DD (−)). Occlusal contact area, occlusal force, masticatory efficiency, tongue pressure, and lip pressure were measured. Lateral cephalometric analysis assessed skeletal and dental patterns. Results: OA group exhibited significantly reduced occlusal contact area (p < 0.0083, η² = 0.12) and occlusal force (p < 0.0083, η² = 0.14) compared to the OC/DD (−) group. Cephalometric analysis revealed that both OA and BDD groups had significantly larger ANB angles (OA: 5.7°, BDD: 5.2°, OC/DD (−): 3.7°; p < 0.0083, η² = 0.21) and FMA angles (OA: 32.4°, BDD: 31.8°, OC/DD (−): 29.0°; p < 0.0083, η² = 0.17) compared to the OC/DD (−) group. No significant differences were observed in masticatory efficiency, tongue pressure, or lip pressure. Conclusions: TMJ structural abnormalities detected via MRI, especially osteoarthritis, are associated with diminished oral function and skeletal Class II and high-angle features in female patients with malocclusion. Although orthodontic treatment is not intended to manage TMDs, MRI-based structural characterization—when clinically appropriate—may aid in treatment planning by identifying underlying joint conditions. Full article

Disused muscle atrophy (DMA) is characterized by skeletal muscle loss and functional decline due to prolonged inactivity. Though evidence remains limited, recent studies suggest that ferroptosis, an iron-dependent, lipid peroxidation-driven form of cell death, may contribute to DMA. Taurine, a natural amino acid enriched in energy drinks, can improve the proliferation and myogenic differentiation potential of myoblasts. This study aimed to investigate whether taurine supplementation could protect against DMA and explore its potential role in modulating ferroptosis. Using a hindlimb suspension-induced DMA model in male C57BL/6J mice (6–8 weeks old), we assessed muscle mass, function, ferroptosis-related markers, histopathological changes, and metabolic alterations. The results showed that taurine supplementation improved muscle strength and morphology while attenuating markers of ferroptosis, including iron accumulation, lipid peroxidation, and glutathione and related protein (NRF2, GPX4, and xCT) depletion. Metabolomic analysis suggested that taurine modulates disorders in glutathione and lipid metabolism, potentially associated with the regulation of the xCT-GSH-GPX4 and AMPK-ACC-ACSL4 pathways. While these findings support a protective role for taurine and a possible link between ferroptosis and DMA, further functional studies are needed to confirm causality and assess the compound’s translational potential. This study provides initial in vivo evidence implicating ferroptosis in DMA and highlights taurine as a promising candidate for future therapeutic exploration. Full article

The biological complexity of sarcopenia presents a major challenge for therapeutic intervention due to the wide range of degenerative changes it induces in skeletal muscle. This study demonstrates the potential of liposomal controlled release systems to address these challenges by combining two bioactive agents with complementary actions: caffeine (CAF), encapsulated in DMPC-based liposomes, and hyaluronic acid methacrylate (HAMA), encapsulated in DOPC-based liposomes. A hybrid system was also developed to deliver both substances simultaneously, aiming to restore tissue function through combined metabolic, anti-inflammatory, and regenerative effects. The liposomes exhibited nanoscale dimensions, spherical morphology, and intact membrane structure, as confirmed by electron microscopy. DLS analysis indicated good colloidal stability and monodisperse size distribution across all formulations, with improved stability observed in the hybrid system. Drug release studies showed a time-dependent profile, with HAMA releasing rapidly and CAF releasing gradually, supporting a dual-action therapeutic approach tailored to the multifactorial pathology of sarcopenia. The biological assays, performed in an established in vitro sarcopenia model, revealed the potential of liposomes co-delivering caffeine and HAMA to mitigate oxidative stress, preserve mitochondrial function, and reduce apoptosis in H₂O₂-damaged myotubes. Full article

Flight loss has independently evolved across nearly all winged insect orders. Comparing the thoracic structures of flightless insects with those of their flight-capable relatives can reveal key characteristics linked with flight. Although flight loss has been widely studied in beetles, exploration of this phenomenon has been limited to taxonomic and geographic distribution studies in the species-rich family Chrysomelidae, with little analysis of thoracic anatomical structures. This study employs a suite of morphological techniques to examine the thoracic structures of two flightless beetle species Chrysolina: sulcicollis and Chrysolina virgata, originating from desert and temperate regions, respectively. A comparison between the two flightless species reveals that C. sulcicollis has fewer tergo-pleural muscles involved in elytral movement likely to save water, but more muscles that contribute to stabilizing larger body structures. Meanwhile, differences are also observed in the elytral base, the anterior corner of the mesal suture, and the setae on the meso-inner region of the epipleuron. Compared to other flight-capable chrysomelid beetles, apart from the absence of flight-related muscles, the two flightless beetles exhibit similar thoracic skeletal structures. The absence of lateral cervical sclerites, along with the presence of muscles Idvm4, 5 and Itpm5, could enhance head mobility as a compensatory adaptation doe the loss of flight capability. Additionally, the greater number of tergo-pleural muscles in the mesothorax of C. virgata could suggest that its elytra serve a specialized function. Compared to other flightless beetles, aside from the similarly reduced flight muscles, these two species have relatively intact thoracic skeletons. Further data on habitat, functional compensation and other related factors are needed to compare their evolutionary processes with those of other flightless beetles. Full article

Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors continually stabilize hypoxia-inducible factor-1α (HIF-1α). These inhibitors are effective in the clinical treatment of renal anemia. However, the effects of continued HIF-1α stabilization on skeletal muscle differentiation remain unclear. This study aimed to investigate the effects of continued HIF-1α stabilization on skeletal muscle differentiation using a HIF-PH inhibitor in both in vitro and in vivo models. We cultured mouse C2C12 myoblasts to differentiate into myotubes with or without FG-4592, a HIF-PH inhibitor. Additionally, we treated nine-week-old male C57BL/6 mice with either FG-4592 or vehicle via intraperitoneal injections three times a week for four weeks. In vitro, FG-4592 treatment stabilized HIF-1α continually. Morphological analysis revealed that 72 h FG-4592 treatment suppressed differentiation of C2C12 myoblasts into myotubes. This treatment decreased the gene and protein expression of MyoD and myogenin, reduced the protein expression of myosin heavy chain (MHC), and increased the gene and protein expression of myostatin. HIF-1α knockdown mitigated the decrease in MHC protein expression induced by FG-4592. In vivo, FG-4592 treatment increased HIF-1α protein expression and decreased MyoD, myogenin, and MHC protein expression in gastrocnemius muscle. These findings suggest that pharmacological HIF-PH inhibition suppresses myoblast differentiation through continued HIF-1α stabilization. Full article

Liaoning cashmere goats is a dual-purpose breed valued for premium cashmere fiber and meat yields, and there is currently a lack of optimized strategies for meat quality, including skeletal muscle development and lipid partitioning. This investigation systematically examines how melatonin administration modulates gastrointestinal microbiota and antioxidant capacity to concurrently enhance skeletal muscle hypertrophy and redirect lipid deposition patterns, ultimately improving meat quality and carcass traits in Liaoning cashmere goats. Thirty female half-sibling kids were randomized into control and melatonin-treated groups (2 mg/kg live weight with subcutaneous implants). Postmortem analyses at 8 months assessed carcass traits, meat quality, muscle histology, plasma metabolites, and gut microbiota (16S rRNA sequencing). Melatonin supplementation decreased visceral adiposity (perirenal, omental, and mesenteric fat depots with a p < 0.05) while inducing muscle fiber hypertrophy (longissimus thoracis et lumborum (LTL) and biceps femoris (BF) with p < 0.05). The melatonin-treated group demonstrated elevated postmortem pH₂₄h values, attenuated muscle drip loss, enhanced intramuscular protein deposition, and improved systemic antioxidant status (characterized by increased catalase and glutathione levels with concomitant reduction in malondialdehyde with p < 0.05). Melatonin reshaped gut microbiota, increasing α-diversity (p < 0.05) and enriching beneficial genera (Prevotella, Romboutsia, and Akkermansia), while suppressing lipogenic Desulfovibrio populations, and concomitant with improved intestinal morphology as evidenced by elevated villus height-to-crypt depth ratios. These findings establish that melatonin-mediated gastrointestinal microbiota remodeling drives anabolic muscle protein synthesis while optimizing fat deposition, providing a scientifically grounded strategy to enhance meat quality. Full article

Fish red blood cells (RBCs) are nucleated, transcriptionally active, and key players in both gas transport and immune responses. They are the primary targets of Orthoreovirus piscis (PRV), the etiological agent of heart and skeletal muscle inflammation (HSMI), which includes three genotypes (PRV-1, PRV-2, and PRV-3), linked to circulatory disorders in farmed salmon. In Chile, PRV-3 affects the coho salmon (Oncorhynchus kisutch), but host–pathogen interactions remain poorly characterized. This study compared the interactions of PRV-3 in coho salmon and PRV-1 in Atlantic salmon (Salmo salar) using RBC infection models. RBCs were isolated from healthy juvenile salmon (n = 3) inoculated with either PRV-1 (Ct = 18.87) or PRV-3 (Ct = 21.86). Poly I:C (50 µg/mL) was used as a positive control for the antiviral response. Cells were monitored for up to 14 days post-infection (dpi). PRV-3 infection in coho salmon RBCs caused significant metabolic disruption, apoptosis from 7 dpi, and correlated with increasing viral loads. In contrast, PRV-1 infection in Atlantic salmon RBCs showed limited apoptosis and maintained cell viability. Coho salmon RBCs upregulated rig-i, mx, and pkr transcripts, indicating activation of the type I interferon pathway, whereas Atlantic salmon RBCs exhibited a more attenuated response. PRV-3 induced notable morphological changes in coho salmon RBCs, although neither PRV-3 nor PRV-1 caused hemolysis. These findings highlight species-specific differences in RBC responses to PRV infection and provide new insights into the pathogenesis of PRV-3 and PRV-1. Full article

As a chronic inflammatory disease, atherosclerosis can affect the occurrence of skeletal muscle autophagy through a variety of mechanisms. Previous studies have demonstrated that exercise enhances autophagic activity through irisin-mediated pathways. Building upon this evidence, this study investigated the effects of a 12-week aerobic exercise training on irisin levels and skeletal muscle autophagy-related proteins in atherosclerotic mice. Male C57BL/6J and ApoE^−/− mice were randomly assigned to four groups: Control Group (C), Aerobic Exercise Group (CE), ApoE^−/− Control Group (AC), and ApoE^−/− Aerobic Exercise Group (AE). Serum and muscle irisin levels were measured by ELISA; the expression levels of FNDC5, AMPK/mTOR pathway proteins and autophagy markers were detected by immunoblots, and muscle morphology was examined using H&E staining. Compared with the C group, the serum levels of TAG, TC, and LDL-C were higher than the AC group. Aerobic exercise increased irisin levels in skeletal muscle, upregulated the expression of LKB1 and p-AMPK, and presented an elevated LC3-II/I ratio, accompanied by reduced mTORC1 expression in CE mice. Aerobic exercise increased FNDC5 expression and irisin levels in serum and skeletal muscle, but also upregulated mTORC1 expression and reduced the LC3-II/I ratio in the AE group. Aerobic exercise enhances irisin synthesis and improves dyslipidemia in ApoE^−/− mice. However, the increased expression of the mTORC1 protein contributed to decreasing the expression of autophagy-related proteins following exercise. Full article

Objectives: This study aims to elucidate the metabolic differences between obese adolescents categorized into low-weight-loss (LWL) and high-weight-loss (HWL) groups. Methods: The objective of this study is to investigate the metabolic characteristics of obese adolescents, with a focus on the statistically significant individual differences observed in weight loss outcomes after the same dietary and exercise training intervention. A four-week exercise and dietary intervention was administered to the participants. Obese adolescents were categorized into LWL (with a weight loss percentage of 5–10%) and HWL (with a weight loss percentage of >10%) groups on the basis of their weight loss outcomes. Post-intervention changes in body morphology and body composition between the two groups were compared using Analysis of Covariance (ANCOVA), with gender as a covariate. Additionally, metabolic changes were analyzed in depth; differential metabolites between the groups were identified through ANCOVA adjusted for gender, followed by pathway analysis. Results: After the four-week exercise intervention, the body morphology and composition of the obese adolescents showed significant improvements compared with those before the intervention (p < 0.001). For example, weight decreased from 80.65 kg to 72.35 kg, BMI decreased from 30.57 kg/m² to 27.26 kg/m², waist circumference decreased from 103.64 cm to 94.72 cm, and body fat percentage decreased from 32.68% to 28.54%. Prior to the exercise intervention, no significant differences in body morphology and composition were observed between the HWL and LWL groups (p > 0.05). After the intervention, the HWL group demonstrated significant improvements in weight, body mass index, waist circumference, body fat percentage, fat mass, fat-free mass, body water amount, and skeletal muscle mass compared with the LWL group (p < 0.001). After controlling for the levels of pre-intervention metabolites, 27 differential metabolites were identified between the HWL and LWL groups. These metabolites were categorized into fatty acids, amino acids, organic acids, carnitines, indoles, benzoic acids, and carbohydrates. Notably, they were significantly enriched in the eight metabolic pathways involved in amino acid metabolism, fatty acid biosynthesis, and coenzyme A biosynthesis. Conclusions: A four-week exercise intervention enhanced the body morphology and physical fitness of obese adolescents, although the degree of weight loss varied among individuals. Considerable weight reduction was significantly correlated with metabolites involved in lipid, amino acid, organic acid, carbohydrate, and gut microbiota metabolism and with the enrichment of pathways involved in amino acid metabolism, fatty acid biosynthesis, and coenzyme A biosynthesis. These findings indicate that intrinsic metabolic characteristics considerably influence individual responsiveness to exercise-based weight-loss interventions. Full article

Background/Objectives: Recent studies have highlighted the role of the gut–muscle axis, suggesting that modulation of the gut microbiota may indirectly benefit skeletal muscle. This study aimed to evaluate the effects of Lactobacillus fermentum (L. fermentum) supplementation in a model of muscle atrophy induced by chronic ethanol (EtOH) intake, focusing on inflammatory and antioxidant mechanisms. Methods: Sixty 12-month-old female Balb/c mice were divided randomly into three groups (n = 20/group): (1) Ethanol (EtOH) group, receiving ethanol daily for 8 and 12 weeks to induce systemic oxidative stress and inflammation; (2) Ethanol + Probiotic (EtOH + P) group, receiving both ethanol and L. fermentum supplementation for the same durations; and (3) Control (Ctrl) group, receiving only water. Muscle samples were analyzed for the fiber morphology, inflammatory markers, oxidative stress indicators, and satellite cell (SC) activity. All data were tested for normality using the Shapiro–Wilk test before applying a parametric analysis. A statistical analysis was performed using one-way ANOVA followed by a Bonferroni post-hoc test. The level of significance was set at p < 0.05. Results: EtOH exposure caused significant atrophy in all muscle fiber types (type I, IIa, and IIb), with the most pronounced effects on oxidative fibers. L. fermentum supplementation significantly reversed atrophy in type I and IIa fibers, accompanied by a significant reduction in IL-6, TNF-α, and Hsp60 expression levels, indicating the protective effect of L. fermentum against oxidative stress and inflammation. Moreover, the probiotic treatment increased MyoD expression in SCs, suggesting enhanced regenerative activity, without histological evidence of fibrosis. Conclusions: These findings suggest that L. fermentum supplementation could counteract EtOH-induced skeletal muscle damage by reducing inflammation and oxidative stress and promoting muscle repair, indicating its potential as an adjuvant, in the therapeutic strategy of models of muscle degeneration. Full article

Skeletal muscle satellite cells (SMSCs) are quiescent stem cells located in skeletal muscle tissue and function as the primary reservoir of myogenic progenitors for muscle growth and regeneration. However, the molecular and metabolic mechanisms governing their differentiation in geese remain largely unexplored. This study comprehensively examined the morphological, transcriptional, and metabolic dynamics of goose SMSCs across three critical differentiation stages: the quiescent stage (DD0), the differentiation stage (DD4), and the late differentiation stage (DD6). By integrating transcriptomic and metabolomic analyses, stage-specific molecular signatures and regulatory networks involved in SMSC differentiation were identified. Principal component analysis revealed distinct clustering patterns in gene expression and metabolite profiles across these stages, highlighting dynamic shifts in lipid metabolism and myogenesis. The PPAR signaling pathway emerged as a key regulator, with crucial genes such as PPARG, IGF1, ACSL5, FABP5, and PLIN1 exhibiting differentiation-dependent expression patterns. Notably, PPARG and IGF1 displayed negative correlations with adenosine and L-carnitine levels, suggesting their role in metabolic reprogramming during myotube formation. Additionally, MYOM2 and MYBPC1 exhibited stage-specific regulation and positively correlated with 2,3-dimethoxyphenylamine. This study provides a foundational framework for understanding muscle development and regeneration, offering valuable insights for both agricultural and biomedical research. Full article