• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.61-68
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• 2007

When an active muscle is stretched, its steady-state isometric force following stretch is greater than that of a purely isometric contraction as the corresponding muscle length, referred to as force enhancement (FE). The purpose of this study was to investigate possible effects of muscle architecture on the FE. While subject performed maximal isometric dorsiflexion (REF) and isometric-stretch-isometric dorsiflexion (ECC) contractions, ankle joint angle and dorsiflexion torque using a dynamometer and electromyography of the tibialis anterior and the medical gastrocnemius muscles were measure. Simultaneously, real-time ultrasound images of the tibialis anterior were acquired. Regardless of the speed of stretch of the ECC contractions. the torques produced during the isometric phase following stretch ($37.3{\pm}1.5\;Nm$ ($10{\pm}3%$ FE) and $38.3{\pm}1.5$ ($12{\pm}3%$ FE) for the ECC contractions with $15^{\circ}$/s and $45^{\circ}$/s stretch speeds, respectively) were greater than those of the REF contractions ($34.5{\pm}2.5\;Nm$). Moreover, the amount of FE was found to be stretch speed dependent. Angles of pennation ($\alpha$) during the isometric phase following stretch were the same for the REF ($15{\pm}1^{\circ}$) and the ECC ($14{\pm}1^{\circ}$(LS), $15{\pm}1^{\circ}$(LF)). During the same phase, muscle thicknesses were the same ($14.9{\pm}0.6$, and $14.9{\pm}0.5\;mm$ for the REF and the ECC contractions, respectively). For a large limb muscle, the tibialis anterior muscle, a similar amount of force enhancement was observed as did for other human skeletal muscles. Architectural variables, pennation angle and thickness, were not systematically different between the REF and ECC contractions when FE occurred. Therefore, the results of this study suggest that muscle architecture may have little influence on the production of FE.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.10
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• pp.1612-1617
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• 2007

In this study, we have compared the skeletal muscle proteome at various stages of porcine postnatal development. Korean native pigs were divided into five postnatal stages of 30, 70, 130, 170 and 300 d and their loin muscles were analyzed for muscle proteome by using two-dimensional electrophoresis and mass spectrometry. We found 5 proteins showing a consistent pattern during skeletal muscle growth. Four proteins were identified as myosin light chain 1 slow-twitch (MLC1sa) isoform, troponin T, triosephosphate isomerase (TIP) and DJ-1 protein. The remaining protein was not identified. Two muscle fiber proteins of MLC1sa isoform and troponin T showed a high expression level at an early postnatal stage and then their levels were decreased markedly during growth stages. On the other hand, the expression of TIP and DJ-1 protein, which are well known as catalysis enzyme and antioxidant-related protein, respectively, were linearly increased during growth stages. Thus, the stage-related muscle proteins may be useful as parameters for understanding the developmental characteristics of biochemical and physiological properties in Korean native pig skeletal muscle.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.585-592
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• 2021

Cisplatin has been reported to cause side effects such as muscle wasting in humans and rodents. The physiological mechanisms involved in preventing muscle wasting, such as the regulation of AKT, PGC1-α, and autophagy-related factor FOXO3a by MuRF 1 and Atrogin-1, remain unclear following different types of exercise and in various skeletal muscle types. Eight-week-old male Wistar rats (n = 34) were assigned to one of four groups: control (CON, n = 6), cisplatin injection (1 mg/kg) without exercise (CC, n = 8), cisplatin (1 mg/kg) + resistance exercise (CRE, n = 9) group, and cisplatin (1 mg/kg) + aerobic exercise (CAE, n = 11). The CRE group performed progressive ladder exercise (starting with 10% of body weight on a 1-m ladder with 2-cm-interval grids, at 85°) for 8 weeks. The CAE group exercised by treadmill running (20 m/min for 60 min daily, 4 times/week) for 8 weeks. Compared with the CC group, the levels of the autophagy-related factors BNIP3, Beclin 1, LC3-II/I ratio, p62, and FOXO3a in the gastrocnemius and soleus muscles were significantly decreased in the CRE and CAE groups. The CRE and CAE groups further showed significantly decreased MuRF 1 and Atrogin-1 levels and increased phosphorylation of AKT, FOXO3a, and PGC1-α. These results suggest that both ladder and aerobic exercise directly affected muscle wasting by modulating the AKT/PGC1-α/FOXO3a signaling pathways regardless of the skeletal muscle type.

• The korean journal of orthodontics
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• v.49 no.4
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• pp.254-264
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• 2019

Objective: To evaluate the short-term changes in masticatory muscle activity and mandibular movement patterns after orthognathic surgery in skeletal Class III patients with facial asymmetry. Methods: Twenty-seven skeletal Class III adult patients were divided into two groups based on the degree of facial asymmetry: the experimental group (n = 17 [11 male and 6 female]; menton deviation ${\geq}4mm$) and control group (n = 10 [4 male and 6 female]; menton deviation < 1.6 mm). Cephalography, electromyography (EMG) for the anterior temporalis (TA) and masseter muscles (MM), and mandibular movement (range of motion [ROM] and average chewing pattern [ACP]) were evaluated before (T0) and 7 to 8 months (T1) after the surgery. Results: There were no significant postoperative changes in the EMG potentials of the TA and MM in both groups, except in the anterior cotton roll biting test, in which the masticatory muscle activity had changed into an MM-dominant pattern postoperatively in both groups. In the experimental group, the amount of maximum opening, protrusion, and lateral excursion to the non-deviated side were significantly decreased. The turning point tended to be shorter and significantly moved medially during chewing in the non-deviated side in the experimental group. Conclusions: In skeletal Class III patients with facial asymmetry, the EMG activity characteristics recovered to presurgical levels within 7 to 8 months after the surgery. Correction of the asymmetry caused limitation in jaw movement in terms of both ROM and ACP on the non-deviated side.

• Korean Journal of Exercise Nutrition
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• v.13 no.2
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• pp.155-160
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• 2009

PURPOSE. The purpose of this study was to investigate the effects of fasting and high-fat diet feeding on uncoupling protein 3 (UCP3) mRNA levels, uncoupling the respiratory chain and producing heat, of skeletal muscle in rat. METHODS. Fasting experiment: Forty Male Sprague-Dawley rats (5 wk) were divided into non-fasting groups (CON) and fasting groups (FG) for 0 day, 0.5 day (12 hr), 1 day, 2 day and 3 day. The rats of CON were sacrificed at 0 and 3 day. High-fat diet experiment: Forty Male Sprague-Dawley rats (5 wk) were divided into low-fat diet groups (LF) and high-fat diet group feeding for 0 day, 0.5 day (12 hr), 1 day, 2 day and 3 day. The rats of LF were sacrificed at 0 and 3 day. Analysis: Analysis of UCP3 mRNA expression was used by Real-time PCR. RESULTS. UCP3 mRNA levels of FG group were increased according to time course for 2 days- fasting but decreased at 3 day-fasting. UCP3 mRNA of HF were increased during HF diet feeding for 2 day, and peaked at 1 day-HF feeding, but decreased 2 day and 3 day-HF feeding CONCLUSION. Therefore, it may be rational that UCP3 is up-regulation when a large amount of fatty acids influx occurs in skeletal muscles as well as might have a role for fine adjustments of energy expenditure.

• Journal of Ginseng Research
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• v.48 no.1
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• pp.52-58
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• 2024

Background: Skeletal muscle denervation leads to motor neuron degeneration, which in turn reduces muscle fiber volumes. Recent studies have revealed that apoptosis plays a role in regulating denervation-associated pathologic muscle wasting. Korean red ginseng (KRG) has various biological activities and is currently widely consumed as a medicinal product worldwide. Among them, ginseng has protective effects against muscle atrophy in in vivo and in vitro. However, the effects of KRG on denervation-induced muscle damage have not been fully elucidated. Methods: We induced skeletal muscle atrophy in mice by dissecting the sciatic nerves, administered KRG, and then analyzed the muscles. KRG was administered to the mice once daily for 3 weeks at 100 and 400 mg/kg/day doses after operation. Results: KRG treatment significantly increased skeletal muscle weight and tibialis anterior (TA) muscle fiber volume in injured areas and reduced histological alterations in TA muscle. In addition, KRG treatment reduced denervation-induced apoptotic changes in TA muscle. KRG attenuated p53/Bax/cytochrome c/Caspase 3 signaling induced by nerve injury in a dose-dependent manner. Also, KRG decreases protein kinase B/mammalian target of rapamycin pathway, reducing restorative myogenesis. Conclusion: Thus, KRG has potential protective role against denervation-induced muscle atrophy. The effect of KRG treatment was accompanied by reduced levels of mitochondria-associated apoptosis.

• Korean Journal of Radiology
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• v.24 no.9
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• pp.849-859
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• 2023

Objective: The prognostic value of the volume and density of skeletal muscles in the abdominal waist of patients with colon cancer remains unclear. This study aimed to investigate the association between the automated computed tomography (CT)-based volume and density of the muscle in the abdominal waist and survival outcomes in patients with colon cancer. Materials and Methods: We retrospectively evaluated 474 patients with colon cancer who underwent surgery with curative intent between January 2010 and October 2017. Volumetric skeletal muscle index and muscular density were measured at the abdominal waist using artificial intelligence (AI)-based volumetric segmentation of body composition on preoperative pre-contrast CT images. Patients were grouped based on their skeletal muscle index (sarcopenia vs. not) and muscular density (myosteatosis vs. not) values and combinations (normal, sarcopenia alone, myosteatosis alone, and combined sarcopenia and myosteatosis). Postsurgical disease-free survival (DFS) and overall survival (OS) were analyzed using univariable and multivariable analyses, including multivariable Cox proportional hazard regression. Results: Univariable analysis showed that DFS and OS were significantly worse for the sarcopenia group than for the non-sarcopenia group (P = 0.044 and P = 0.003, respectively, by log-rank test) and for the myosteatosis group than for the non-myosteatosis group (P < 0.001 by log-rank test for all). In the multivariable analysis, the myosteatotic muscle type was associated with worse DFS (adjusted hazard ratio [aHR], 1.89 [95% confidence interval, 1.25-2.86]; P = 0.003) and OS (aHR, 1.90 [95% confidence interval, 1.84-3.04]; P = 0.008) than the normal muscle type. The combined muscle type showed worse OS than the normal muscle type (aHR, 1.95 [95% confidence interval, 1.08-3.54]; P = 0.027). Conclusion: Preoperative volumetric sarcopenia and myosteatosis, automatically assessed from pre-contrast CT scans using AI-based software, adversely affect survival outcomes in patients with colon cancer.

• Applied Microscopy
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• v.41 no.4
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• pp.277-284
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• 2011

This study was conducted to determine the antiseptic effect of stabilized chlorine dioxide (S-$ClO_2$) on muscle tissue of rats. Skeletal muscle of 8-week old Sprague-Dawley rats was used. Light and transmission electron microscopic findings were observed in the control group, which was not treated with stabilized chlorine dioxide, and in the experimental group, which was treated with a stabilized chlorine dioxide powder in aqueous solution. According to the LM and TEM observations, the day 1 control group showed the initiation of endomysium collapse resulting in an unclear boundary of muscle fibers, and partial collapse of the mitochondrial membranes. All endomysium had collapsed, and bacteria were observed among muscle fibers in the day 2 and later groups. Shapes of muscles were not distinguishable in day 3 or later groups. In contrast, the day 1 and 3 experimental groups revealed detailed structure of typical muscles, but partial collapse of the mitochondrial membranes was observed in the day 3 and later groups. Subsequently, connective tissues collapsed and structures in the shape of concentric circles were observed. In summary, the day 1 control group showed the initial collapse of tissues, and shapes were not distinguishable in the day 3 and later groups because most of the tissues had collapsed. In contrast, the day 3 experimental group showed partial collapse, but the overall shapes of muscles were maintained as time went on, confirming the antiseptic effect of stabilized chlorine dioxide on muscles.

• Journal of Life Science
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• v.26 no.4
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• pp.387-397
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• 2016

The purpose of this study was to determine if heat shock proteins are involved in autophagy in skeletal muscle. We used the autophagy flux strategy, which is an LC3 II/p62 turnover assay conducted with and without an autophagy inhibitor, to determine whether 17-DMAG (an Hsp90 inhibitor/Hsp72 activator) stimulates autophagy in skeletal muscle. We treated C2C12 cells with 17-DMAG (500 nM) for 24 hr with and without the autophagy inhibitor (Bafilomycin A1, 200 ng/ml), and we injected C57BL/6 mice i.p. with 17-DMAG (10 mg/kg) daily for 7 days with and without colchicine as an autophagy inhibitor (0.4 mg/kg/day, administered on the last 2 days). C2C12 myotubes and tibialis anterior muscles were harvested for analysis of mTOR-dependent autophagy signaling pathway proteins and autophagic marker proteins (p62 and LC3 II) by Western blot analysis. The blots showed that 17-DMAG upregulated hsp72 and decreased Akt protein levels and S6 phosphorylation in C2C12 cells. However, an in vitro autophagic flux assay demonstrated that 17-DMAG did not increase LC3 II and p62 protein concentrations to a greater extent than Bafilomycin A1 treatment alone. Similarly, 17-DMAG increased Hsp72 protein levels and decreased the expression of Akt and the phosphorylation of S6 in mouse skeletal muscle. However, unlike the response seen in C2C12 myotubes, the p62 protein levels were significantly decreased in 17-DMAG-treated mouse skeletal muscle (~50%; p<0.05). The LC3 II protein levels in 17-DMAG-treated mice were increased ~2-fold more when degradation was inhibited by colchicine (p<0.01). This suggests that 17-DMAG stimulates basal autophagy in skeletal muscle but is not found in C2C12 myotubes.

• Physical Therapy Korea
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• v.22 no.3
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• pp.98-105
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• 2015

Muscular dystrophy is a hereditary musculoskeletal disorder caused by a mutation in the dystrophin gene. Duchenne muscular dystrophy (DMD) is one of the most common, and progresses relatively faster than other muscular dystrophies. It is characterized by progressive myofiber degeneration, muscle weakness and ultimately ambulatory loss. Since it is an X-linked recessive inheritance, DMD is mostly expressed in males and rarely expressed or less severe in females. The most effective measurement tool for DMD is magnetic resonance imaging (MRI), which allows non-invasive examination of longitudinal measurement. It can detect progressive decline of skeletal muscle size by measuring a maximal cross-sectional area of skeletal muscle. Additionally, other techniques in MRI, like $T_2$-weighted imaging, assess muscle damage, including inflammation, by detecting changes in $T_2$ relaxation time. Current MRI techniques even allow quantification of metabolic differences between affected and non-affected muscles in DMD. There is no current cure, but physical therapist can improve their quality of life by maintaining muscle strength and function, especially if treatment (and other forms of medical intervention) begins in the early stages of the disease.