Background: Rhabdomyosarcoma is the most common soft tissue sarcoma among children which has two major subtypes: embryonal rhabdomyosarcoma (ERMS) and alveolar rhabdomyosarcoma (ARMS). Distinction between these subtypes is mandatory to choose proper treatment and to determine prognosis. Histopathologic study is the main method, but nowadays molecular studies like PCR are also used. The aim of this study was to evaluate the frequency of PAX3 and PAX7 mutations in children with rhabdomyosarcoma.Materials and Methods: In this cross- sectional survey, Paraffin blocks of 34 Rhabdomyosarcoma cases with mean age of 6.3±2.9 years were studied in Mofid Children's Hospital's Pathology Department, Tehran, Iran, during a 10-year period. Tumoral lesions dissected and embedded in paraffin blocks for PCR study (Tissue dissection method). Pure RNA extraction, cDNA synthesis, and PCR process were performed according to iNtRON biotechnology company kits’ protocols. All of these cases were analyzed regardingPAX3 and PAX7 mutations.Results: Out of 34 cases, 32 were ERMS and two were ARMS. None of the ERMS samples was t (2; 13) or t (1; 13) positive. Moreover, two ARMS cases were negative for PAX3 and PAX7 mutations. No significant difference was seen for age below and above five years (P=0.69) as well as for tumor location (trunk tumor and limbs/head tumor) (P=0.11).Conclusions: This study revealed lack of PAX3 and/or PAX7 mutations in both ERMS and ARMS. However, careful morphological evaluation cannot be replaced by the PCR-based t(2; 13) and t(1; 13) assay  of  childhood sarcomas, it can be used to make certain current histopathological diagnosis.

Background and Purpose: Aging leads to a reduction in muscle fibers, the number of stem cells, and their regenerative potential Strength training is utilized as a factor to enhance muscle strength and performance. This study aimed to investigate the effect of six weeks of TRX training on paired box 7 (PAX7) protein levels and functional performance indices of upper and lower body strength, flexibility, agility, and cardiorespiratory endurance in elderly women. Materials and Methods: This applied research utilized a pre-test/post-test design. Thirty-two elderly women (age, 62.5 ± 5.16 years; height,162.60 ± 4.68 cm; weight 73.92 ± 9.29 kg; body mass index, 27.97 ± 3.38 kg/m2) were randomly assigned to either a training group (n = 16) or a control group (n = 16). The training protocol consisted of six weeks of TRX exercises, two sessions per week. Eight exercises, including various rows, assisted squats, biceps curls, chest presses, shoulder presses, squats, triceps extensions, and a squat-biceps curl-row combination, were performed for 50 minutes per session. Six Fullerton functional fitness tests were administered as dependent variables in both the pre-test and post-test. Blood samples were collected 48 hours before the first session and after the last session. PAX7 protein levels were measured using the ELISA method. Following confirmation of data normality using the Shapiro-Wilk test and homogeneity of variance using Leven's test, a one-way analysis of covariance (ANCOVA) was conducted using SPSS 26 to test the hypotheses. Results: Six weeks of TRX resistance training significantly increased PAX7 protein levels in the training group compared to the control group (p= 0.001). Furthermore, the training program significantly improved upper body strength (p = 0.011), upper body flexibility (p = 0.001), lower body flexibility (p = 0.001), agility (p = 0.018), and cardiorespiratory endurance (p = 0.008) in the elderly women. However, six weeks of TRX resistance training did not significantly affect lower body strength (p = 0.479). Conclusion: Six weeks of TRX training resulted in a significant increase in serum PAX7 protein levels in elderly women and improved functional performance indices of upper body strength, upper and lower body flexibility, and cardiorespiratory endurance. Based on these findings, TRX training can be utilized to enhance functional fitness in elderly individuals. However, given the lack of significant impact on lower body strength and its critical role in preventing falls and improving quality of life, it is recommended to implement a modified protocol with more targeted lower body exercises to enhance lower limb strength, functional capacity, and postural control in elderly populations

Objective: Satellite cells play an important role in muscle regeneration, which this process can be affected by different genes including PAX7 and MyoD. Exercise training known as an important strategy for mediating the satellite cell’, s function. Therefore, the main purpose of the present study is to investigate the changes in PAX7 and MyoD protein expression in response to eccentric and concentric resistance exercise in healthy young men. Materials and Methods: In this semi-experimental and cross-sectional study, 10 healthy men (age range 18-30 years old) participated. They were randomly divided into two equal groups (n=5) to perform one of two high-intensity eccentric or concentric knee extensions muscle contraction protocols. The contractions included a maximum of 12 sets of 10 repetitions, with a 30 second rest time interval between sets. PAX7 and MyoD protein expression was assessed using Immunohistochemistry analysis from the Vastus Lateralis muscle needle biopsy samples that have been taken 24 hours before and 3 to 4 hours after the end of the exercise protocol. Results: We observed that the PAX7 protein expression level increased significantly after eccentric (47. 75%) and concentric (39. 21%) (P=0. 01) intervention. While, the MyoD protein expression level reduced (38. 14%) significantly following acute eccentric resistance exercise (P=0. 01). Conclusion: It seems that eccentric or concentric muscular contraction modulates the expression of PAX7 and MyoD protein expression in the skeletal muscle, with further effects observed in eccentric resistance exercise.

Sheep satellite cells more than satellite cells of the rat and mouse are similar to human satellite cells. These cells are widely used in the modeling and treatment of diseases like heart insufficiency, neurological diseases, muscular dystrophy, cerebral cell transplantation for the treatment of migraines, screening, and the production of new drugs. This study was aimed to isolate and culture primary satellite cells (PSCs) obtained from sheep fetus, and perform clonal expansion of transfected PSCs. Skeletal muscle tissues of hind limbs were collected from sheep fetuses obtained from a local abattoir. After enzymatic digestion, flasks were replaced after 3 hours to isolate non-myogenic cells, such as fibroblasts. After six days, the cells were differentiated to myoblasts. Using a differentiation medium containing the horse serum, myotube cells were observed in the flask, indicating that the cultured cells were satellite cells. The mRNA expression of the PAX7 gene was used to confirm the presence of satellite cells. In addition, the results showed that satellite cells grow in a culture medium containing 5% FBS without differentiation, while 10% FBS initiates their differentiation.

Myocardial infarction is a disease that not only influences cardiovascular system, but also influences other body systems including skeletal muscles. Thus, the aim of this study was to examine two type of interval training with low and high intensity on gene expression of MyoD and Pax7. 24 Wistar rats (age: 10 weeks) were selected and underwent a coronary artery blocking surgery. Eventually, they were randomly divided into 4 groups: low intensity training (LIT) (n=6), high intensity training (HIT) (n=6), sham (n=6) and control (con) (n=6). 4 weeks after operation, subjects trained for 6 weeks, 3 session per week. After 6th week, subjects were anesthetized and killed and their soleus muscle were separated for further analysis. Data from RT-PCR technique were quantified by Δ Δ Ct formula and analyzed by one-way ANOVA test after Shapiro-Wilk and Leven tests. The results showed no significant differences in the effect of training intensities on MyoD and Pax7 among groups. However, it has shown that training has positive effects of cardiovascular system and muscular disorders resulted from MI, further studies with more control of other effective factors are required for a definite comment on the effects of different types of training on markers such as MyoD and Pax7 which are highly associated with treating muscle atrophy.

Background & Objective: Many cancer patients suffer from cachexia or cancer-induced muscle atrophy. Cachexia can have various causes one of which is the reduction of muscle regeneration. Resistance training has been suggested as one of the proper stimulator of increasing muscular regeneration. The present study aimed at evaluating the effect of resistance training on two factors of regeneration including PAX7 and eMHC, tumor-free weight and tumor weight of mice. Materials & Methods: This study was a kind of experimental intervention. Subjects of the study included 10 BALB-C mice (age: 6 weeks) which CT-26 tumor was transplanted to them. Mice were divided into two groups of resistance training (n=5) and control (n=5) randomly. Training group performed six-week progressive resistance training and control groups were kept in cages without any exercise intervention. At the end of the experiment, gastrocnemius muscle was taken for evaluating related factors. Data were analyzed using the independent t-test. Results: There was no significant difference in PAX7 between two groups of training and control, but eMHC reduced significantly in training compared to the control group (P=0. 038). Tumor-free bodyweight of training group increased significantly compared to the control group (P=0. 0004) and there was no significant difference in tumor weight between two groups of training and control. Conclusion: Although resistance training does not increase tumor growth but probably reduce some muscle regeneration factors in cancer-bearing mice. So, for improving muscular regeneration in cachexia bearing patients, probably resistance training is not a good choice. However, more future researches are required.

Extended AbstractBackground and Aim: Sarcopenia is a prevalent age-related condition characterized by the progressive loss of skeletal muscle mass, strength, and function. This deterioration leads to significant health consequences, including impaired mobility, loss of independence, increased risk of falls, fractures, and even mortality (3). From a pathophysiological standpoint, sarcopenia is associated with multiple interrelated mechanisms, such as reduced satellite cell activity, chronic inflammation, oxidative stress, diminished muscle protein synthesis, and impaired  neuromuscular signaling (1, 4). Several key proteins have been identified as crucial molecular indicators in the progression or reversal of sarcopenia. For instance, Paired Box 7 (PAX7) is essential for satellite cell activation and muscle regeneration, and its reduction signals impaired muscle repair associated with aging (5). Nuclear factor kappa B (NF-κB), a central regulator of chronic inflammation, contributes to muscle atrophy and exhibits elevated activity in aged muscle tissue (7). Forkhead box O (FOXO3) is another essential factor involved in regulating apoptosis, autophagy, and protein turnover (10, 11). Additionally, Nicotinic acetylcholine receptor (nAChRs) play a critical role at the neuromuscular junction, facilitating nerve-to-muscle signaling; their reduction compromises muscle contraction and strength (14). While pharmacological interventions have shown limited efficacy in managing sarcopenia, exercise—particularly resistance and endurance training—has emerged as a safe and effective strategy. Resistance training primarily enhances muscular strength, whereas endurance training exerts anti-inflammatory effects and improves metabolic function (13, 17). Given these distinct but complementary mechanisms, the present study aimed to investigate and compare the effects of six weeks of resistance versus endurance training on the levels of four key proteins in the gastrocnemius muscle of female rats modeled with sarcopenia.Materials and Methods: This experimental laboratory study was conducted on 20 adult female Wistar rats (aged 12 ± 1 weeks, weight 200–250 g). All animals were housed under standard environmental conditions (controlled temperature, humidity, and lighting) with ad libitum access to food and water. The rats were randomly assigned to four equal groups: (1) healthy control, (2) sarcopenic control, (3) sarcopenia + resistance training, and (4) sarcopenia + endurance training. Sarcopenia was induced by intraperitoneal injection of dexamethasone (0.1 mg/kg) for 10 consecutive days. Resistance training consisted of ladder climbing at an 80° incline with a 110 cm height, while carrying a load equivalent to 60% of body weight attached to the tail. This was performed three times weekly for six weeks. Endurance training involved treadmill running at moderate intensity (60–70% of maximum speed capacity), with gradual increases over the six-week period. At the end of the intervention period, animals were anesthetized using appropriate agents and euthanized. The gastrocnemius muscle of the hind limbs was dissected for protein analysis. Western blotting was used to quantify PAX7, NF-κB, FOXO3, and nAChR protein levels. For statistical analysis, data normality was assessed using the Shapiro–Wilk test, and homogeneity of variances was confirmed using Levene’s test. Group differences were analyzed using one-way ANOVA, followed by Tukey’s post hoc test for pairwise comparisons. Statistical significance was accepted at p<0.05.Findings: Dexamethasone administration effectively induced sarcopenia in the model, as evidenced by significant reductions in body weight and decreased levels of PAX7 and nAChR, alongside marked increases in NF-κB and FOXO3. These alterations reflect activation of inflammatory and catabolic pathways, as well as impaired muscle regenerative capacity. Both resistance and endurance training significantly reversed these changes. PAX7 levels increased in both intervention groups, with endurance training producing a significantly greater enhancement, indicating more effective stimulation of satellite cells and muscle regeneration. NF-κB levels significantly decreased following endurance training, highlighting its potent anti-inflammatory effect. Conversely, FOXO3, which is associated with muscle degradation and cell death, was reduced in both exercise groups, with a greater reduction observed in the resistance training group, suggesting superior efficacy in inhibiting muscle catabolism. nAChR expression improved significantly in both training groups compared to the sarcopenic control, although no significant difference was found between resistance and endurance protocols. Conclusion: Overall, the results demonstrate that both resistance and endurance training confer beneficial effects on sarcopenia-related molecular pathways. Endurance training was more effective in stimulating muscle regeneration and attenuating inflammatory responses, whereas resistance training more strongly inhibited catabolic processes and supported neuromuscular stability. These differential adaptations highlight the potential for targeted exercise prescriptions to address specific pathophysiological aspects of sarcopenia.This study demonstrates that both resistance and endurance training exert significant, beneficial effects on molecular markers associated with sarcopenia. Endurance training enhances muscle regeneration and reduces inflammation through increased PAX7 and decreased NF-κB, whereas resistance training more effectively suppresses muscle degradation via reduction of FOXO3. These distinctions highlight the potential for either modality to be used independently or in combination, depending on therapeutic objectives. The findings underscore the value of targeted physical exercise as a non-pharmacological, cost-effective, and safe strategy for managing sarcopenia. Future studies with larger sample sizes, prolonged intervention periods, and comprehensive molecular analyses are warranted to further clarify the mechanisms underlying exercise-induced muscle adaptations and optimize individualized treatment protocols for sarcopenia.Ethical Considerations: All ethical principles in this research were meticulously adhered to by the researchers.Funding: The authors of this article declare that they have not received any financial support from any organization.Conflicts of interest: The authors report no conflicts of interest in relation to this manuscript.

Background: Box 7 protein (PAX7) and myogenic differentiation (MyoD) proteins are the essential proteins to regulate the satellite cell and muscle hypertrophy. Objectives: We aimed to investigate the effect of resistance training (RT) on PAX7 and MyoD in soleus and extensor digitorum longus (EDL) muscles of old rats. Methods: In this experimental study, 12 old female rats were randomly divided into two groups including RT and control groups. The RT program was three days a week for eight weeks, in which the rats climbed a one-meter vertical ladder with 26 steps. The carried weights varied from 50% of body weight in the first week to 100% of body weight in the 8th week. Kolmogorov-Smirnov test and independent sample t test was used for statistical analysis (P≤, 0. 05). Results: MyoD protein in RT group significantly increased in soleus and EDL muscles compared with the control group (P = 0. 001). Also, Pax7 significantly increased in the soleus muscle in the RT group compared with control group (P = 0. 002),nevertheless, there was no significant difference in Pax7 protein in the EDL muscle between the RT and control groups (P = 0. 10). Conclusion: RT can lead to proliferation and renewal of satellite cells in the soleus and EDL muscles by increasing PAX7 and MyoD proteins.

Introduction: Myopathy caused by diabetes can accelerate the disease process in diabetic people. Myopathy has important indicators in muscle tissue related to regeneration and intracellular metabolism in skeletal muscles. The current study aimed to evaluate the effect of eight weeks of resistance training in hypoxia on the content of PAX 7 and PGC-1α proteins in the gastrocnemius muscle of type 2 diabetic rats. Methods: This experimental study was conducted on 24 male Wistar rats for six weeks after induction of type 2 diabetes. Rats were divided into three groups: healthy control (HC), diabetic control (DC), and hypoxia group (HPX). Resistance training was applied for eight weeks under oxygen deficiency conditions in the groups of resistance training in hypoxia. The tissue sample was taken from the biceps muscle after finishing the exercises and evaluated to measure the concentration of PAX7 and PGC-1α proteins. The results were analyzed by one-way analysis of variance at a significance level α ≤0. 05. Results: There was a significant difference in PAX7 and PGC-1α proteins between the research groups (P=0. 0001). Induction of diabetes led to a significant decrease in PAX7 compared to the control group. PGC1-α protein levels also decreased significantly in the diabetes induction group compared to the control group (P=0. 0001). However, exposure to hypoxia did not change the gene expression values of this variable compared to the diabetic patient group (P=0. 451). Conclusion: Exposure to temporary and passive hypoxia can be considered as a suggested strategy to improve indicators related to type 2 diabetes in humans.

Background and objectives: Osteoarthritis is one of the most common arthritic diseases and a main cause of pain and disability. Simultaneous downexpression of paired box 7 (Pax7) and myogenin genes, as indicators of satellite cells activation is evident in osteoarthritis. This study assessed effects of an exercise training course and stem cell injection on the expression of Pax7 and myogenin in gastrocnemius muscle of rats with arthritis. Methods: Thirty five male rats aged 6– 8 weeks and weighing 250– 300 g were divided into five groups: control, patient, exercise, mesenchymal stem cell (MSC), and exercise+MSC. Osteoarthritis was induced in rats by surgery. The training program consisted of 30 minutes of running on a non-slip treadmill at a speed of 16 m/min. The rats were injected with 1×106 cells/kg MSC. The expression of Pax7 and myogenin was measured by real– time PCR. Data were analysed with SPSS (version 23) using one-way analysis of variance. Results: Both Pax7 and myogenin were significantly overexpressed in the exercise+MSC group compared to the patient group (P<0. 001). Conclusion: The combination of MSC therapy and training had more positive effects on Pax7 and myogenin expression compared to training and MSC therapy alone.