• 한국식품과학회지
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• 제18권3호
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• pp.226-233
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• 1986

근원섬유단백질의 열안정성에 대한 pH의 영향에 있어서 소의 근육의 경우에 fiber type에 따라 차이를 보이지 않으나, 닭의 근육의 경우에는 fiber type에 따라 안정 pH 범위에 차이를 나타내었다. 한편, 이온강도 및 유기용매의 농도변화에 따른 영향에 있어서는 이온강도가 증가함에 따라 그리고 유기용매의 농도가 증가함에 따라 변성속도가 증가하였으며, 또한 actomyosin의 열안정성이 myosin과 HMM의 열안정성보다 높은 것으로 나타났다. 열안정성에 대한 열역학량$(D\;value,Z\;value,\;{\Delta}H^{\ddag},\;{\Delta}S{\ddag},\;{\Delta}G^{\ddag})$은 red muscle과 white muscle 사이에 명백한 차이를 보였으며 white muscle이 red muscle보다 높은 열안정성을 나타내었으며, 동물의 종류에 따라서도 현저한 차이를 보였다.

• Journal of Nutrition and Health
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• 제55권1호
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• pp.70-84
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• 2022

Purpose: Skeletal muscles display significant heterogeneity in metabolic responses, owing to the composition of metabolically distinct fiber types. Recently, numerous studies have reported that in skeletal muscles, suppression of genes related to fatty acid channeling alters the triacylglycerol (TAG) synthesis and switches the energy substrates. However, such responses may differ, depending on the type of muscle fiber. Hence, we conducted in vitro and animal studies to compare the metabolic responses of different types of skeletal muscle fibers to the deficiency of fatty acyl-CoA synthetase (Acsl)6, one of the main fatty acid-activating enzymes. Methods: Differentiated skeletal myotubes were transfected with selected Acsl6 short interfering RNA (siRNA), and C57BL/6J mice were subjected to siRNA to induce Acsl6 deficiency. TAG accumulation and expression levels of insulin signaling proteins in response to acute glucose supplementation were measured in immortalized cell-based skeletal myotubes, oxidative muscles (OM), and glycolytic muscles (GM) derived from the animals. Results: Under conditions of high glucose supplementation, suppression of the Acsl6 gene resulted in decreased TAG and glycogen synthesis in the C2C12 skeletal myotubes. The expression of Glut4, a glucose transporter, was similarly downregulated. In the animal study, the level of TAG accumulation in OM was higher than levels determined in GM. However, a similar decrease in TAG accumulation was obtained in the two muscle types in response to Acsl6 suppression. Moreover, Acsl6 suppression enhanced the phosphorylation of insulin signaling proteins (Foxo-1, mTORc-1) only in GM, while no such changes were observed in OM. In addition, the induction ratio of phosphorylated proteins in response to glucose or Acsl6 suppression was significantly higher in GM than in OM. Conclusion: The results of this study demonstrate that Acsl6 differentially regulates the energy metabolism of skeletal muscles in response to glucose supplementation, thereby indicating that the fiber type or fiber composition of mixed muscles may skew the results of metabolic studies.

• Journal of Korean Biological Nursing Science
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• 제14권1호
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• pp.49-56
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• 2012

Purpose: The purpose of this study was to compare the effects of anorexia induced by consecutive low-dose and high-dose of cisplatin (CDDP) on the hindlimb muscles of rats. Methods: Male Sprague-Dawley rats were assigned to three groups: Control group (C) received a saline (the same dose and duration as the low CDDP group), the high-dose cisplatin (High CDDP) group received a single 5 mg/kg dose of cisplatin, the consecutive low-dose cisplatin (Low CDDP) group had 1 mg/kg of cisplatin administered for five consecutive days. On the 8th day the soleus and gastrocnemius muscles were dissected. Body weight, food intake, activity, muscle weight, Type I, II fiber cross-sectional area (CSA) of the dissected muscles were measured. Results: Body weight, food intake, muscle weight and Type I, II fiber CSA of the High CDDP and Low CDDP groups were significantly less than the C group. The High CDDP group showed significant decreases, compared to the Low CDDP group, in body weight, food intake, activity score, muscle weight and Type I, II fiber CSA. Conclusion: Hindlimb muscle atrophy occurs due to anorexia induced by both consecutive low-dose and high-dose cisplatin. The muscle atrophy induced by consecutive low-dose cisplatin is less apparent than high-dose cisplatin.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.1046-1053
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• 1999

The musculotendon model is presented to show the declines in muscle force and shortening velocity during muscle fatigue due to the repeated functional electrical stimulation (FES). It consists of the nonlinear activation and contraction dynamics including physiological concepts of muscle fatigue. The activation dynamics represents $Ca^{2+}$ binding and unbinding mechanism with troponins of cross-bridges in sarcoplasm. It has the constant binding rate or activation time constant and two step nonlinear unbinding rate or inactivation time constant. The contraction dynamics is the modified Hill type model to represent muscle force - length and muscle force - velocity relations. A muscle fatigue profile as a function of the intracellular acidification, pH is applied into the contraction dynamics to represent the force decline. The computer simulation shows that muscle force and shortening velocity decline in stimulation time. And we validate the model. The model can predicts the proper muscle force without changing its parameters even when existing the estimation errors of the optimal fiber length. The change in the estimate of the optimal fiber length has an effect only on muscle time constant in transient period not on the tetanic force in the steady-state and relaxation periods.

• Journal of Korean Biological Nursing Science
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• 제13권1호
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• pp.1-7
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• 2011

Purpose: The purpose of this study was to compare the hypertrophic effects of low-intensity exercise on weight, myofibrillar protein content and Type I, II fiber cross-sectional area of hindlimb muscles of rats between every other day exercise and every day exercise. Methods: Adult male Sprague-Dawley rats were assigned to 1 of 3 groups: control group (C, n=6), experimental group 1 (E1, n=7) and experimental group 2 (E2, n=7). Rats in E1 group had 7 sessions (every other day) and those in E2 group had 14 sessions (every day) of exercise in which they ran on a treadmill for 30 min/day at 10 m/min. Results: Muscle weight, cross-sectional area of type I fiber and myofibrillar protein content of soleus and myofibrillar protein content of plantaris in E1 group, and myofibrillar protein content of soleus and cross-sectional area of type I fiber of plantaris in E2 group were greater than those in C group. Cross-sectional area of type I fiber of soleus of E1 group was higher than E2 group while cross-sectional area of type I fiber of plantaris of E2 group was higher than E1 group. Conclusion: Hypertrophy of hindlimb muscles occurs from every other day exercise similar to every day exercise.

• 대한본초학회지
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• 제23권2호
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• pp.159-168
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• 2008

Objectives : The present study has been undertaken to investigate the effects of Dipsaci Radix on Muscle Fiber Atrophy and MyoD Expression in Gastrocnemius of MCAO Rats Methods : In order to investigate effects of Dipsaci radix on the skeletal muscle atrophy following stroke, cerebral infarct was induced by the middle cerebral artery occlusion (MCAO) in the rats. Water extract of Dipsaci radix (184.4 mg/100 g) was treated for 4 weeks, once a day orally, after the MCAO. Effects were evaluated with muscle fiber type composition and cross-sectioned area of muscle fibers in gastrocnemius of the unaffected & affected hind limbs. And MyoD protein expression in gastrocnemius was demonstrated with immunohistochemistry and western blotting. Results : Obtained results were as follows; 1. Infarct volume was not attenuated by Dipsaci radix treatment in the MCAO rats. 2. At the affected-side hind limb of the MCAO rats, the increase of type-I fibers and the decrease of type-II fibers were induced by Dipsaci radix treatment. 3. At the affected-side hind limb of the MCAO rats, decreases of cross-sectioned areas of type-I and type-II fibers were attenuated by Dipsaci radix treatment. 4. At the affected-side hind limb of the MCAO rats, MyoD positive cells were increased by Dipsaci radix treatment. 5. At the affected-side hind limb of the MCAO rats, MyoD expressions were increased by Dipsaci radix treatment. Conclusions : These results suggest that Dipsaci radix has a protective effect against muscle atrophy, through the inhibition of the muscle cell apoptosis, following the central nervous system demage.

• 한국전문물리치료학회지
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• 제7권3호
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• pp.34-48
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• 2000

The purpose of this study was to determine the effects of mild-intensity exercise training on the denervated muscle atrophy in the sciatic nerve injured rat. Thirty-six male Sprague-Dawley rats (250~300 g) were randomly assigned into three groups; sham-denervated group (n=8), denervated group (n=8), and denervated-exercised group (n=20). Exercise consisted of treadmill running at 20 m/min speed with 0% grade for 30 min/day. The animals were decapitated at the second and sixth weeks postcrush. Soleus and medial gastrocnemius were immediately excised to be weighed. Type I and II fibers of the muscles were differentiated by m-ATPase (pH 9.4) stain, and fiber diameters were evaluated. The results were as follows: 1) The weight of the soleus and medial gastrocnemius muscles showed a tendency to increase in both the denervation-exercised groups compared to the denervated group. 2) In the 2-week denervation-exercised group, type II fiber diameter of soleus and type I fiber diameter of medial gastrocnemius were increased significantly compared to the denervated control group. 3) In the 6-week denervated-exercised group, type I fiber diameter of soleus and type II fiber diameter of medial gastrocnemius were hypertrophied significantly compared to sham-denervated group. The results of this study suggested that treadmill exercise partially prevented denervation atrophy in the soleus and medial gastrocnemius of the rat.

• 한국축산식품학회지
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• 제39권2호
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• pp.197-208
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• 2019

The aim of this study was to investigate the relation of sensory quality traits of cooked beef to fresh meat quality and histochemical characteristics, especially muscle bundle traits, in the longissimus thoracis muscle of Hanwoo steers. Cooking loss negatively correlated with softness, initial tenderness, chewiness, rate of breakdown (RB), and amount of perceptible residue (AR) after chewing (p<0.05), and drip loss showed negative correlation with RB and AR (p<0.05). All the attributes of tenderness exhibited negative correlation with the Warner-Bratzler shear force value (p<0.05). Marbling score and the intramuscular fat (IMF) content showed positive correlation with all the organoleptic characteristics, including tenderness attributes, juiciness, and flavor (p<0.05). Regarding histochemical characteristics, muscle fiber size did not have a significant correlation with all the sensory quality traits, although the area percentage of type I fiber was related with softness, initial tenderness, and chewiness (p<0.05). On the contrary, the characteristics of muscle bundle were related to all the sensory tenderness attributes (p<0.05), and the sensory tenderness increased with smaller muscle bundle size (p<0.05). These results suggest that the IMF content and bundle characteristics can be used as indicators for explaining the variations in sensory tenderness in well-marbled beef.

• Asian-Australasian Journal of Animal Sciences
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• 제33권5호
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• pp.704-711
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• 2020

Objective: Muscle fiber types, numbers and area are crucial aspects associated with meat production and quality. However, there are few studies of pig muscle fibre traits in terms of the detection power, false discovery rate and confidence interval precision of whole-genome quantitative trait loci (QTL). We had previously performed genome scanning for muscle fibre traits using 183 microsatellites and detected 8 significant QTLs in a White Duroc×Erhualian F₂ population. The confidence intervals of these QTLs ranged between 11 and 127 centimorgan (cM), which contained hundreds of genes and hampered the identification of QTLs. A whole-genome sequence imputation of the population was used for fine mapping in this study. Methods: A whole-genome sequences association study was performed in the F₂ population. Genotyping was performed for 1,020 individuals (19 F₀, 68 F₁, and 933 F₂). The whole-genome variants were imputed and 21,624,800 single nucleotide polymorphisms (SNPs) were identified and examined for associations to 11 longissimus dorsi muscle fiber traits. Results: A total of 3,201 significant SNPs comprising 7 novel QTLs showing associations with the relative area of fiber type I (I_RA), the fiber number per square centimeter (FN) and the total fiber number (TFN). Moreover, one QTL on pig chromosome 14 was found to affect both FN and TFN. Furthermore, four plausible candidate genes associated with FN (kinase non-catalytic C-lobe domain containing [KNDC1]), TFN (KNDC1), and I_RA (solute carrier family 36 member 4, contactin associated protein like 5, and glutamate metabotropic receptor 8) were identified. Conclusion: An efficient and powerful imputation-based association approach was utilized to identify genes potentially associated with muscle fiber traits. These identified genes and SNPs could be explored to improve meat production and quality via marker-assisted selection in pigs.

• Asian-Australasian Journal of Animal Sciences
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• 제31권2호
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• pp.301-308
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• 2018

Objective: This study compared the meat quality, muscle fiber characteristics, and fatty acids between Jinjiang yellow cattle (JJ) and F1 Simmental${\times}$Jinjiang yellow cattle (SJ) which were offered the same diet. Methods: Six JJ and six SJ individuals were reared and fattened from 10 to 26 months of age. After feeding, the highrib (HR), ribeye (RB), and tenderloin (TL) samples were taken from the carcass for meat quality evaluations. Results: The results showed that growth performance of SJ was higher than that of JJ (higher live weight and average daily gain), and the hot carcass weight of SJ was higher than that of JJ (p<0.05). pH of JJ was higher than that of SJ in TL (p<0.05); the color of $a^{\ast}$ of SJ was higher than that of JJ in TL and RB (p<0.05); the cooking loss of SJ was significantly lower than that of JJ in TL and RB (p<0.05); the shear force value was significantly lower in SJ compared to JJ (p<0.05); the muscle fiber diameter was higher and the fiber density was lower in SJ compared to JJ in HR and TL (p<0.05); compared to SJ, the muscles of JJ had higher saturated fatty acid (SFA) composition; the sum of monounsaturated fatty acid and polyunsaturated fatty acid (PUFA) were lower in the muscle of JJ; the mRNA expressions of myosin heavy chain-I (MyHC-I) and MyHC-IIa were higher in SJ compared to JJ in muscle of HR and RB; the mRNA expressions of MyHC-IIx and MyHC-IIb were lower in SJ compared to JJ in HR and RB (p<0.05). Conclusion: Meat quality and fatty acid profile differed between SJ and JJ; the muscle of SJ had higher $a^{\ast}$ and SFA; SJ had lower cooking loss, shear force and PUFA compared to the muscle of JJ. In addition, the type and development characteristics of the muscle fiber had some difference between SJ and JJ; these might be factors which caused the differences in meat quality and fatty acid profile between SJ and JJ.