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The cortex of Cinnamomumcassia Presl (Cinnamomi Cortex: CC) has commonly been used for weight control in traditional medicines, but without a scientific basis. Therefore, this study was undertaken to investigate the anti-obesity effect of CC extract in a high-fat diet (HFD)-induced obese mouse model and in C2C12 mouse skeletal muscle cells. Male C57BL/6 mice were fed a normal diet or a HFD for 16 consecutive weeks, and orally administered CC extract (100 or 300mg/kg) or metformin (250mg/kg; positive control) daily for 16 weeks. CC extract administration significantly decreased body weights, food intakes, and serum levels of glucose, insulin, total cholesterol and ALT levels, prevented oral glucose tolerance and insulin resistance, inhibited the protein expressions of MyHC and PGC1$\alpha$ and the phosphorylation of AMPK, suppressed lipid accumulation in liver, decreased adipocyte size and increased muscle mass in obese mice. For this in vitro study, C2C12 myoblasts were differentiated into the myotubes for five days, and then treated with CC extract (0.1 or 0.2mg/ml) for 24h. CC extract significantly increased ATP levels by increasing the mRNA expressions of mitochondrial biogenesis-related factors, such as, PGC1$\alpha$, NRF-1, and Tfam, and the phosphorylations of AMPK and ACC. Our results suggest CC extract controls weight gain in obese mice by inhibiting lipid accumulation and increasing energy expenditure, and that its action mechanism involves the up-regulation of mitochondrial biogenesis in skeletal muscle cells.

In vitro incubation of tissues; in particular, skeletal muscles from rodents, is a widely-used experimental method in diabetes research. This experimental method has previously been validated, both experimentally and theoretically. However, much of the method's experimental data remains unclear, including the high-rate of lactate production and the lack of an observable increase in glycogen content, within a given time. The predominant hypothesis explaining the high-rate of lactate production is that this phenomenon is dependent on a mechanism in glycolysis that works as a safety valve, producing lactate when glucose uptake is super-physiological. Another hypothesis is that existing anoxia forces more ATP to be produced from glycolysis, leading to an increased lactate concentration. The lack of an observable increase in glycogen content is assumed to be dependent on limitations in sensitivity of the measuring method used. We derived a mathematical model to investigate which of these hypotheses is most likely to be correct. Using our model, data analysis indicates that the in vitro incubated muscle specimens, most likely are sensing the presence of existing anoxia, rather than an overflow in glycolysis. The anoxic milieu causes the high lactate production. The model also predicts an increased glycogenolysis. After mathematical analyses, an estimation of the glycogen concentration could be made with a reduced model. In conclusion, central anoxia is likely to cause spatial differences in glycogen concentrations throughout the entire muscle. Thus, data regarding total glycogen levels in the incubated muscle do not accurately represent the entire organ. The presented model allows for an estimation of total glycogen, despite spatial differences present in the muscle specimen.

Peripheral nerve injury changes the kinetics of neurotrophins. The production of several neurotrophins increases at the site of injury. Although numerous reports have described changes in neurotrophins over time in areas of nerve injury, neurotrophin mRNA is present at very low levels in target tissues, making accurate quantitation difficult. We developed a reverse transcription–polymerase chain reaction/high-performance liquid chromatography (RT-PCR/HPLC) method that enables accurate quantitation of neurotrophin mRNA. We then attempted to quantitate mRNA levels for nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) produced by skeletal muscle innervated by the sciatic nerve following transection and reattachment of the nerve in mice. In addition, wet weights of the muscle were measured and changes in weight over time were determined. The results indicated that neurotrophin production in muscle increases as a result of peripheral nerve denervation due to transection, and decreases with nerve regeneration and reinnervation resulting from reattachment.

Purpose: We investigated the kinematics of nerve growth factor (NGF)mRNA and brain-derived neurotrophic factor (BDNF)mRNA in a skeletal muscle following spinal cord and peripheral nerve injuries by utilizing the reverse-transcription polymerase chain reaction/high-performance liquid chromatography (RT-PCR/HPLC) method. Methods: We made mice models of spinal cord transection and sciatic nerve transection, plus sham and control groups. After RNA extraction from gastrocnemius muscle of mice, RT-PCR was done. We measured the levels of NGFmRNA and BDNFmRNA in a skeletal muscle following spinal cord and peripheral nerve injuries by utilizing the RT-PCR/HPLC method. All values are analyzed and graphed as means ±SED. Bonferroni test (Post-hoc test) was used when two values were compared. Differences were considered statistically significant when p < 0.05. Results: According to the wet muscle weight, at day 7, a significant difference was found between the peripheral lesion and control group, and at days 14 and 28, significant differences were found between the spinal and peripheral lesion and control group. According to the NGFmRNA, in the peripheral nerve injury group, the levels increased up to day 28 and when compared with the control group, the levels were significantly higher at days 14 and 28. According to the BDNFmRNA, levels at days 2, 7, 14, and 28 were significantly lower in the spinal cord injury group than in the control group. However, in peripheral nerve injury group, when compared with the control group, the levels significantly increased at days 7, 14, and 28. Conclusion: We clarified marked differences in chronological changes in neurotrophin kinetics in a skeletal muscle between spinal cord injury and peripheral nerve injury.

The role of antioxidant supplementation on muscle recovery after disuse is unknown. The aim was to investigate the effect of Vitamin C and E supplementation on muscle recovery after hindlimb suspension. Twenty-two Wistar rats were allocated into 4 groups: exercise with supplementation (VIT, $n=5$); exercise with placebo (PLA, $n=5$); hindlimb suspension (SUSP, $n=6$), and control (CON, $n=6$). All groups, except for CON, were submitted to a hindlimb suspension protocol for 10 days. Then, VIT and PLA underwent 10 days of a rehabilitation protocol consisting of exercise on a treadmill. VIT received vitamin C (250 mg/kg/day) and E (360 mg/kg) during rehabilitation. Samples of soleus and tibialis anterior were prepared for cross-sectional area (CSA) and biochemical analysis. Both VIT (1265.6m$\mu$², 95% CI: 1234.6–1290.3) and PLA (1280.9m$\mu$², 95% CI: 1296.4–1354.9) presented higher CSA of the soleus in relation to CON (816.66m$\mu$², 95% CI: 866.3–904.0, $P$$<$ 0.05) with no difference between them. Both VIT (1276.9m$\mu$², 95% CI: 1378.7–1484.6) and PLA (1573.3m$\mu$², 95% CI: 1553.9–1651.5) presented higher tibialis anterior CSA in relation to CON (1041.56m$\mu$², 95% CI: 1119.1–1185.2, $P$$<$ 0.05). In this muscle, CSA of PLA was higher than VIT ($P$$<$ 0.05). Vitamin’s supplementation attenuated tibialis anterior hypertrophy following the rehabilitation protocol.

The effect of endurance exercise training on mechanical properties of skeletal muscle with chronic ethanol ingestion was determined in this study. Three to four-week-old male Wistar rats were randomly assigned to four groups: control (CON), control with exercise (CON/EXE), ethanol (ETH), and ethanol with exercise (ETH/EXE). The CON/EXE and ETH/EXE groups were trained to run for 12 weeks on a motor driven treadmill. ETH and ETH/EXE groups were adapted to a liquid alcohol diet (Lieber–DeCarli). Tetanic, twitch force generation, specific force, fatigue time, and shortening velocity of extensor digitorum longus (EDL) and soleus muscles were tested by using an in vitro muscle testing system. Our study shows that exercise does not improve the contractile properties of skeletal muscle with chronic ethanol ingestion indicated by similar twitch force and fatigue time between ETH/EXE and ETH groups in Types I and II fibers, and by lowered tetanic and specific forces in Type I fibers in ETH/EXE group compared to ETH group, possibly due to damage induced by oxidative stress. Future studies on interaction of the biochemical changes and contractile properties of the skeletal muscle with chronic ethanol ingestion will be conducted to better understand mechanisms behind alterations in contractile properties.

With the aim to build an accurate skeletal muscle simulation model, the biomechanical modeling and solution method of skeletal muscle were developed. First, the Mooney–Rivlin model, polynomial model, exponential model, logarithmic model, combined exponential and polynomial model were compared. The biomechanical model of skeletal muscle was built by combining the exponential and polynomial models. Second, the geometric non-linearity problem and material non-linearity problem of the biomechanical model were solved by using the finite element method. The program for this solution was implemented using Visual Studio 2012. Finally, the simulation results were compared to the experimental results. The maximum error between the simulation curve and the experiment stress–strain curve was 0.00149MPa. Finite element simulation for the lateral femoral muscle was conducted using the program developed in this study.

Skeletal muscle energy metabolism plays a very important role in controlling movement of the whole body and has important theoretical guidance for making exercise training plans and losing weight. In this paper, we developed a mathematical model of skeletal muscle excitation–contraction pathway based on the energy metabolism that links excitation to contraction to explore the effects of different metabolic energy systems on calcium ion changes and the force during skeletal muscle contraction. In this paper, a membrane potential model, a calcium cycle model, a cross-bridge dynamics model and an energy metabolism model were established. Finally, the physiological phenomenon of calcium ion transport and calcium ion concentration change of the sarcoplasm was simulated. The results show that the phosphagen system has the fastest metabolic rate and the phosphagen system has the largest impact on the explosive power of skeletal muscle exercise. The specific characteristics of the three metabolic energy systems supporting skeletal muscle movement in vivo were also analyzed in detail.

In this study, we aimed to provide safe exercises with automatic service for easy access to active seniors, develop Smart One Repetition Maximum (1RM) measurement system applying electronic load that can reduce injuries, and optimize exercise effects by accurately evaluating physical functions and exercise effects. In this study, a smart, customized exercise and 1RM measurement system was developed to improve and maintain the daily living ability of healthy older adults. This system applies a power brake to provide a safe and detailed exercise load for older adults and consists of six types of exercises, including leg extension, leg press, long pull, in and out thigh, abdominal, and chest press exercises. The subjects of this study were 30 adults aged 65 years or older who had no history of musculoskeletal or nervous system disorders in the past 6 months and who attended an elderly fitness center in Gwangju city. Whole-body aerobic exercise was performed using a sedentary bicycle for 20min before exercise. Exercise load was performed by converting the weight of 30RM based on the 1RM measured before evaluation. The exercises were chest press, long pull, abdominal flexion, hip adduction, leg extension, and leg press. All the exercises were performed 30 times in a set, three sets a day, 3–5 times a week, with 5min of rest between workouts. As a result of the experiment, the maximum muscle strength for all exercise modes increased significantly ($p<0.05$), and a safe muscle strength enhancement effect for the elderly was observed. These results suggest that the smart, customized exercise system developed in this study can positively result in a safe increase in the muscle strength of the elderly.

The musculoskeletal system, containing bones, cartilage, skeletal muscles, tendons, ligaments, and some other tissues, is a perfect system that undergoes the external and internal load properly and controls the body’s motion efficiently. In this system, skeletal muscle is obviously indispensable. People have been studying the mystery of skeletal muscle mechanics for the last 80 years. Many modeling methods have been used to study skeletal muscles. Among these methods, multi-scale modeling methods are increasingly frequently used in studying musculoskeletal systems, especially those of skeletal muscles. In this review, we summarize the multi-scale modeling methods in studying works of skeletal muscle modeling reported so far. Then, several multi-scale methods of other tissues which possibly could be used in research on skeletal muscle modeling are discussed. Finally, the future research direction and the main challenges of multi-scale skeletal muscle modeling are briefly presented.

Cardiac and skeletal muscles are two tissues that would benefit from an electrically conductive scaffold to regenerate lost or lower functioning areas. By augmenting polymeric scaffolds with conductive elements, the contractile process for both muscles could increase. In this review, the components reviewed include polyaniline (PANi), gold (Au) nanoparticles, and carbon nanotubes (CNT). PANi has been combined with several polymers and increased the conductivity of the scaffolds. It is biocompatible, but increases mechanical properties and decreases scaffold elongation. Tissue engineering using nanoparticles is an emerging area and considerable research focuses on determining possible toxicity due to nanoparticle concentration. Contradicting data exists for both Au nanoparticles and CNT. Smaller Au nanoparticles damage cardiac tissue in vivo while larger ones do not. By comparison, in vitro data shows no harmful results for skeletal muscle cells. Data for CNT is just as diverse as the amount, orientation and further purification or functionalization could all play a role in determining biocompatibility. Future research should focus on establishing the conductivity level needed for each muscle tissue to ascertain the amount of conductive element needed so the most suitable one can be utilized.

We present the theory and application of non-invasive or minimally invasive imaging of bioelectromagnetic sources. We are not concerned with imaging secondary effects of the sources (that might be used to infer their location), such as changes in tissue oxygenation, blood flow, or glucose utilization (as with BOLD or dynamic gadolinium functional MRI strategies, or PET). Thus, we are directly concerned with providing images of source currents or source potentials. These sources reside in “excitable tissues”, such as brain, heart, gut, and skeletal muscle.

While we will not be conducting a comprehensive literature survey, this chapter is intended to provide an overview of the general approaches and trends in bioelectromagnetic imaging that presently characterize the field. Within reason, we attempt this by considering the relevant physiology, physics, engineering, and mathematics that in concert allow a coherent understanding of the present state of affairs. Accordingly, this chapter's sections are arranged as follows:

• General Principles

— Modeling of excitable tissue

— Physics of bioelectromagnetism

— Engineering issues: Signal acquisition

— Mathematical methods

• Source Categories

— Brain: Source physiology, dipole localization, imaging formulations, linear versus nonlinear problems

— Heart: Source physiology, endocardial, epicardial, and transmembrane potential imaging

— Smooth and Skeletal muscle: Source physiology, inverse problems related to electromyography and electrogastrography.

Engineered skeletal muscle grafts have made great progress during the past decades, benefiting from a growing understanding of mechanobiology and stem cell differentiation. Current techniques are widely varied, ranging from in vitro methods following the classical tissue engineering paradigm to in situ approaches such as host cell recruitment. In different ways, all of these try to supply mechanical toughness while providing the necessary signals for differentiation and maturation of the engineered skeletal muscle.