• Journal of Korean Institute of Industrial Engineers
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• v.5 no.2
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• pp.21-36
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• 1979

Static muscle contractions when prolonged or frequently repeated result in discomfort, fatigue, and musculosketal injuries. An analytic and quantitative model has been developed in order to expand the working knowledge on muscle fatigue. In this paper, three Markov models of muscle fatigue are developed. These models are based on motor unit fatigue-recovery characteristics obtained from information on motor unit behavior as it relates to fatigue and graded exertions. Three successively more realistic models are developed that involve: (1) homogeneous motor units with intensity-dependent fatigue rates and state-independent recovery rates (the HMSI model); (2) homogeneous motor units, intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model); and (3) non-homogeneous motor units (i.e., Type S and Type F), intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model). The result indicate that a simple stochastic model provide a means to analyze the complex nature of muscle fatigue in sequential static exertions.

• Journal of Korean Medicine Rehabilitation
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• v.18 no.1
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• pp.47-63
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• 2008

Objectives : Eucommiae cortex is reported that it helps bone and skeletal muscle stronger. In case of bone, many report is presented, but reports related to skeletal muscle are rarely existed. So in order to investigate effects of Eucommiae cortex on the skeletal muscle atrophy following stroke, cerebral infarct was induced by the middle cerebral artery occlusion (MCAO) in the rats. Methods : In order to induce MCAO rats, nylon suture was advanced and then blocked middle cerebral artery(MCA). Water extract of Eucommiae cortex was treated for 15 days, once a day orally, after the MCAO. Effects were evaluated with muscle weights, muscle fiber type composition, cross-sectioned area of muscle fibers in soleus and gastrocnemius of the unaffected and affected hind limbs. And MyoD protein expression in gastrocnemius was demonstrated with immunohistochemistry and western blotting. Results : In the affected hind limb of the MCAO rats, muscle weight loss of gastrocnemius and tibialis anterior muscles were attenuated by Eucommiae cortex treatment. In soleus muscle of the affected hind limb of the MCAO rats, increase of type-I fibers and decrease of type-II fibers were induced by Eucommiae cortex treatment. In soleus muscle of the affected hind limb of the MCAO rats, decrease of cross-sectioned areas of type-I fibers was attenuated by Eucommiae cortex treatment. In gastrocnemius muscle of the affected hind limb of the MCAO rats, increase of type-I fibers and decrease of type-II fibers were induced by Eucommiae cortex treatment. In gastrocnemius muscle of the affected hind limb of the MCAO rats, decreases of cross-sectioned areas of type-I and type-II fibers were attenuated by Eucommiae cortex treatment. In gastrocnemius muscle of the affected and unaffected hind limb of the MCAO rats, MyoD expressions were increased by Eucommiae cortex treatment. Conclusions : These results suggest that Eucommiae cortex has a protective effect against muscle atrophy, through the inhibition of the muscle cell apoptosis, following the central nervous system demage.

• Korean Journal of Agricultural Science
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• v.44 no.4
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• pp.586-594
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• 2017

Mitochondrial activity affects skeletal muscle energy metabolism and phenotype. To address whether mitochondrial activity can modulate muscle phenotype in vitro, protein expression of myosin heavy chain (MyHC) in C2C12 muscle cell lines was investigated after treated with antimycin A, an inhibitor of oxidative phosphorylation in mitochondria. Fully differentiated C2C12 myotubes were administrated with different concentration of antimycin A including 0, 100, 200, 500, 700, and 1000 ng/mL. After 72 h treatment, myosin heavy chain isoform expression and related enzyme activity (lactate dehydrogenase; LDH and creatine kinase) were analyzed. Administration of antimycin A changed expression of MyHC in C2C12 myotubes showing a shift from slow to fast twitching muscle type. Protein expression of MyHC type 2b (fast twitching muscle type) was decreased (P < 0.05) by antimycin A treatment (500, 700, and 1000 ng/mL) when compared with control group. Administration of antimycin A (1000 ng/mL), however, decreased (P < 0.05) MyHC type I (slow twitching muscle type). Interestingly, LDH activity was increased (P < 0.05) by antimycin A treatment. Results from our current study proposed a possibility that skeletal muscle phenotype, including MyHC and LDH activity, can be shifted from slow to fast twitching type by inhibiting the mitochondrial activity in C2C12 myotubes.

• Journal of Oral Medicine and Pain
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• v.13 no.1
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• pp.61-69
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• 1988

The study of the muscle fiver composition and the muscle fiver type conversion during unilateral edentulous condition was undertaken in the rostral superficial masseter muscle of the whiter rat. 16 4-week-old male white rats weighting approximately 130gm that crowns of left upper and lower molare were cut intentionally, were divided into 4 groups (one control group and 3 experimental groups). After experimental groups were sacrificed by etherization in 6 days($E_1$), 18 days($E_2$) and 36 days($E_3$) separately, samples of the rostral superficial masseter muscle were obtained bilaterally and the proportion of type I, type IIA, type IIB, and type IIC fibers was determined and counted according to their histochemical activity of myosin ATPase (at pH 9.4, pH 4.6, and pH 4.2)and PAD staining. The obtained results were as follows : 1. The rostral superficial masseter muscle of the white rat contained approximately 47.5% type I fiber and 52.5% type II fiber. 2. Type I/ Type II ratio of molar-present side was increased significantly in the group E2 (18 days group) 3. Type IIA fiber was increased at molar-present side and decreased at molar-absent side in experimental groups.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.19-40
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• 2002

The purpose of this study was to determine the effect of DHEA on Type I(soleus) and II muscles(plantaris, gastrocnemius) in a focal brain ischemia model rat. Thirty-seven male Sprague-Dawley rats with $200{\sim}250g$ body weights were randomly divided into four groups : CINS(cerebral ischemia + normal saline), CIDH(cerebral ischemia + DHEA), SHNS(sham + normal saline), SHDH (sham + DHEA). Both the CINS and CIDH groups were undergone a transient right middle cerebral artery occlusion operation. In the SHNS and SHDH groups, a sham operation was done. DHEA was administered daily at a dose of 0.34mmol/kg, and normal saline was administered daily at the same dose by intraperitoneal injection for 7days after operation. Cerebral infarction in the CINS and CIDH groups was identified by staining with 2% triphenyltetrazolium chloride solution for 60 minutes. The data were analyzed by Kruskal-Wallis test and Mann-Whitney U test using the SPSSWIN 9.0 program. The results were summarized as follows: 1) The muscle weights of soleus(Type I), plantaris and gastrocnemius(Type II) in CINS group were significantly less than those of the SHNS group(p<.01). The muscle fiber cross-sectional area of the CINS group was significantly less than that of the SHNS group in Type I muscle fiber of the soleus and Type II muscle fiber of the plantaris and gastrocnemius(p<.05). The myofibrillar protein content of the CINS group was significantly less than that of the SHNS group in the left gastrocnemius and right soleus(p<.05). 2) The muscle weights of the soleus, plantaris and gastrocnemius except the unaffected side of the plantaris in the CIDH significantly increased compared to those of the CINS group(p<.05). The muscle fiber cross-sectional area of the CIDH group significantly increased compared to that of the CINS group in Type II muscle fiber of the plantaris and gastrocnemius(p<.05). The myofibrillar protein content of the CIDH group significantly increased compared to that of the CINS group in the left soleus(p<.05). 3) On the post-op 8 day, the body weight of the CINS group was significantly less than that of the CIDH, SHNS and SHDH groups(p<.01). Total diet intake of the CINS and CIDH groups was significantly less than that of the SHNS and SHDH groups(p<.01). Based on these results, it was identified that muscle atrophy could be induced during the 7 days after cerebral infarction, and DHEA administration during the early stage of cerebral infarction might attenuate muscle atrophy.

• Food Science of Animal Resources
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• v.36 no.5
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• pp.583-593
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• 2016

The aim of this study was to investigate the effects of morphological characteristics of porcine muscle fibers on growth performance, muscle fiber characteristics, and pork quality taken from the longissimus dorsi muscle. A total of 239 crossbred pigs (164 castrated males and 75 females) were used in this study. Experimental pigs were categorized by the total number of muscle fiber (TNF: High and Low) and cross sectional area of muscle fiber (CSAF: Large, Middle, and Small). Their combinations were classified into six groups (High-Large, HL; High-Middle, HM; High-Small, HS; Low-Large, LL; Low-Middle, LM; Low-Small, LS). The TNF and CSAF were significantly (p<0.05) correlated with growth rate and carcass productivity, while the only of the type I number had no meaningful relationships excluding the correlation with loin area (p<0.001). The proportion of type I area was positively correlated with pH_{45 min} while the proportion of type IIB area was negatively correlated with pH_{45 min} and pH_{24 h} (p<0.05). Drip loss and protein denaturation had strong relationships with the proportion of type IIB number or area. The HL group exhibited the greatest growth performance. In addition, the HL group had significantly greater values in protein solubility than the other groups. In conclusion, this study suggest that high TNF combined to large CSAF improve the ultimate lean meat productivity and assure normal meat quality simultaneously with increased both proportion of number and area of type I, type IIA muscle fibers and lowered proportion of number and area of type IIB.

• Journal of Korean Academy of Nursing
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• v.36 no.7
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• pp.1232-1241
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• 2006

Purpose: The purpose of this study was to examine the effects of cerebral ischemia on Type I(soleus) and Type II(plantaris, gastrocnemius) muscles, and to determine the effects of isometric contraction training by electro- stimulation on Type I and II muscles in cerebral ischemia model rats. Method: Twenty-five male Sprague-Dawley rats were randomly divided into four groups: ST(stroke), STES(stroke+electrostimulation), SH(sham) and SHES (sham+electrostimulation). The ST and STES groups received a transient right middle cerebral artery occlusion operation. The SH and SHES groups received a sham operation. The STES and SHES groups had daily isometric contraction training by electrostimulation(100Hz, 45mA, 7.5V) on hindlimb muscles for 7days. Result: Plantaris and gastrocenmius muscle weight, myofibrillar protein contents of soleus and gastrocnemius, and the muscle fiber cross-sectional area of gastrocnemius in the ST group significantly decreased compared with the SH group. Soleus, plantaris, gastrocnemius muscle weight, myofibrillar protein contents of soleus and gastrocnemius, and the Type I muscle fiber cross-sectional area of soleus and the Type II muscle fiber cross-sectional area of gastrocnemius in the STES group significantly increased compared with the 57 group. Conclusion: Hindlimb muscle atrophy occurs after acute stroke and isometric contraction training by electrostimulation during early stages of a stroke attenuates muscle atrophy of Type I and Type II muscles.

• Applied Microscopy
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• v.27 no.1
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• pp.1-12
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• 1997

Dorsal and ventral epithelium of leech, Whitemenia edentula, were observed, using both light and electron-microscope. Results are as follows. Epithelia are composed of simple columnar or irregularly-shaped epithelium, the transveral folds were seen in the cross-sectioned dorsal and ventral epithelia, but only longitudinal folds(depth $500{\mu}m$, width $350{\mu}m$) were discovered in the ventral epithelium. As to muscular tissue under the dorsal epithelium of Whitemenia edentula, that of longitudinal muscle layer is thicker and more developed than that of circular muscle layer. Seven gland cells (type-A, B, C, D, E, F and H cells) and one pigment cell (type-G cell) were discovered in the whitemenia edentula. Those were identified as three kinds of the neutral mucopolysaccharide granoles (type-A, B and F cells), two kinds of acidic mucopolysaccharide granules (type-C and D cells), and two kinds of non-reactive granules respectively (type-E and F cells). The glanules of the type-A and type-B gland cells ae electronly high-dense, and surrounded by the muscular tissue. As to the distribution of gland cells, the type-A, type-B, type-C, type-D, type-I and type-H gland cells were discovered only between the connective tissue and the circular muscle layer, while type-F gland cells were discovered only between tile circular muscle layer and the longitudinal muscle layer.

• Food Science of Animal Resources
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• v.39 no.6
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• pp.988-999
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• 2019

To investigate the relationship between muscle fiber characteristics and meat quality traits by age of Korean native black goat (KNBG), four muscles (longissimus dorsi, LD; psoas major, PM; semimembranosus, SM; gluteus medius, GM) were obtained from five adult goat (AG; 18 months old) and five young goat (YG; 9 months old). PM muscle had the highest fiber number percentage (FNP) and fiber area percentage (FAP) of type I, followed by SM, GM, and LD muscles. FNP and FAP of type IIB were significantly (p<0.001) higher in AG than those in YG. YG had higher L^* values but lower b^* values than AG. The highest L^* and b^* values were observed in LD muscle (p<0.001). Age and muscle type had detrimental (p<0.001) effect on shear force and collagen content for all muscle in AG as compared to YG. YG had significantly (p<0.001) higher myofibrillar fragmentation index (MFI) than AG for all four muscles. These results suggest that muscle fiber compositions of different muscle types of KNBG depend on age, resulting in variations of meat color, MFI, collagen content, and shear force.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.122-130
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• 2009

The analysis of human movement requires the knowledge of the Hill type muscle parameters, the muscle-tendon and moment arm length change as a function of joint angles. However, values of a subject's muscle parameters are very difficult to identify. It turns out from a sensitivity analysis that the tendon slack length and maximum muscle force are the two critical parameters among the Hill-type muscle model. Therefore, it could be claimed that the variation of the tendon slack length and maximum muscle force from the Delp's reference data will change the muscle characteristics of a subject remarkably. A numeric optimization method to search these tendon parameters specific to a subject is proposed, and the accuracy of the developed algorithm is evaluated through a numerical simulation.