• Transactions of Materials Processing
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• v.18 no.1
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• pp.20-25
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• 2009

A finite element analysis was carried out for a 4:1 planar contraction die for polymer melts using the viscoelastic constitutive equation of Leonov. Viscoelastic fluids showed significant differences in pressure drop and birefringence in contraction and expansion flows. The pressure drop was higher and the birefringence smaller in expansion than in contraction flow. The difference increased with increasing flow rate. The nonlinear Leonov model was shown to describe the viscoelastic effects observed in experiments.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.103-107
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• 2015

Objective: Pelvic floor muscles (PFMs) form the base of the abdomino-pelvic cavity and also the PFMs function is important for urinary continence. PFMs training (PFMT) is considered to be the first method for PFM dysfunction. This study demonstrated correct PFMs contraction among commonly used different contraction methods for PFMT. Design: Cross-sectional study. Methods: In this study, nineteen middle-aged (40-70 years) women participated. To evaluate PFM function, ultrasonography was used to measure the distance of the bladder base movement. The distance of the PFM movements were calculated at rest and during the other contractions. The following four different contraction methods were performed randomly: (1) PFM contraction, (2) abdominal drawing-in maneuver (ADIM), (3) anal contraction, and (4) hip adductor muscle contraction. The participants held the contraction for 3 seconds for a total of 3 times with a 30 seconds rest period between each trial. The mean of three measurements in each position were obtained and compared with that in the resting position. Results: The bladder base movement values were significantly greater when comparing PFM with ADIM and hip adductor contractions (p<0.05). The bladder base movement values were significantly greater when comparing ADIM and anal contractions with hip adductor contractions (p<0.05). Conclusions: The results of this study suggest that performing PFM contractions is the best method among the common methods for PFMT. Performing PFM contractions was more effective than the other contraction methods.

• Molecules and Cells
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• v.38 no.7
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• pp.616-623
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• 2015

P2 receptors are membrane-bound receptors for extracellular nucleotides such as ATP and UTP. P2 receptors have been classified as ligand-gated ion channels or P2X receptors and G protein-coupled P2Y receptors. Recently, purinergic signaling has begun to attract attention as a potential therapeutic target for a variety of diseases especially associated with gastroenterology. This study determined the ATP and UTP-induced receptor signaling mechanism in feline esophageal contraction. Contraction of dispersed feline esophageal smooth muscle cells was measured by scanning micrometry. Phosphorylation of $MLC_{20}$ was determined by western blot analysis. ATP and UTP elicited maximum esophageal contraction at 30 s and $10{\mu}M$ concentration. Contraction of dispersed cells treated with $10{\mu}M$ ATP was inhibited by nifedipine. However, contraction induced by $0.1{\mu}M$ ATP, $0.1{\mu}M$ UTP and $10{\mu}M$ UTP was decreased by U73122, chelerythrine, ML-9, PTX and $GDP{\beta}S$. Contraction induced by $0.1{\mu}M$ ATP and UTP was inhibited by $G{\alpha}i_3$ or $G{\alpha}q$ antibodies and by $PLC{\beta}_1$ or $PLC{\beta}_3$ antibodies. Phosphorylated $MLC_{20}$ was increased by ATP and UTP treatment. In conclusion, esophageal contraction induced by ATP and UTP was preferentially mediated by P2Y receptors coupled to $G{\alpha}i_3$ and $G{\alpha}q$ proteins, which activate $PLC{\beta}_1$ and $PLC{\beta}_3$. Subsequently, increased intracellular $Ca^{2+}$ and activated PKC triggered stimulation of MLC kinase and inhibition of MLC phosphatase. Finally, increased $pMLC_{20}$ generated esophageal contraction.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.4
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• pp.287-297
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• 2001

Contraction of smooth muscle is initiated by an increase in cytosolic $Ca^{2+}$ leading to activation of $Ca^{2+}$/ calmodulin-dependnet myosin light chain (MLC) kinase and phosphorylation of MLC. The types of contraction and signaling mechanisms mediating contraction differ depending on the region. The involvement of these different mechanisms varies depending on the source of $Ca^{2+}$ and the kinetic of $Ca^{2+}$ mobilization. $Ca^{2+}$ mobilizing agonists stimulate different phospholipases $(PLC-{\beta},\;PLD\;and\;PLA_2)$ to generate one or more $Ca^{2+}$ mobilizing messengers $(IP_3\;and\;AA),$ and diacylglycerol (DAG), an activator of protein kinase C (PKC). The relative contributions of $PLC-{\beta},\;PLA_2$ and PLD to generate second messengers vary greatly between cells and types of contraction. In smooth muscle cell derived form the circular muscle layer of the intestine, preferential hydrolysis of $PIP_2$ and generation of $IP_3$ and $IP_3-dependent\;Ca^{2+}$ release initiate the contraction. In smooth muscle cells derived from longitudinal muscle layer of the intestine, preferential hydrolysis of PC by PLA2, generation of AA and AA-mediated $Ca^{2+}$ influx, cADP ribose formation and $Ca^{2+}-induced\;Ca^{2+}$ release initiate the contraction. Sustained contraction, however, in both cell types is mediated by $Ca^{2+}-independent$ mechanism involving activation of $PKC-{\varepsilon}$ by DAG derived form PLD. A functional linkage between $G_{13},$ RhoA, ROCK, $PKC-{\varepsilon},$ CPI-17 and MLC phosphorylation in sustained contraction has been implicated. Contraction of normal esophageal circular muscle (ESO) in response to acetylcholine (ACh) is linked to $M_2$ muscarinic receptors activating at least three intracellular phospholipases, i.e. phosphatidylcholine-specific phospholipase C (PC-PLC), phospholipase D (PLD) and the high molecular weight (85 kDa) cytosolic phospholipase $A_2\;(cPLA_2)$ to induce phosphatidylcholine (PC) metabolism, production of diacylglycerol (DAG) and arachidonic acid (AA), resulting in activation of a protein kinase C (PKC)-dependent pathway. In contrast, lower esophageal sphincter (LES) contraction induced by maximally effective doses of ACh is mediated by muscarinic $M_3$ receptors, linked to pertussis toxin-insensitive GTP-binding proteins of the $G_{q/11}$ type. They activate phospholipase C, which hydrolyzes phosphatidylinositol bisphosphate $(PIP_2),$ producing inositol 1, 4, 5-trisphosphate $(IP_3)$ and DAG. $IP_3$ causes release of intracellular $Ca^{2+}$ and formation of a $Ca^{2+}$-calmodulin complex, resulting in activation of myosin light chain kinase and contraction through a calmodulin-dependent pathway.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.6
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• pp.1107-1115
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• 1996

An investigation made of the easing contraction ratio according to sewing condition (seam line; wp, wf, 45$^{\circ}$ bias, stitch density; 13 stitch/cm (0.8 mm), 9 stitch/cm (1.1 mm), 6.5 stitch/ cm (1.5 mm), 5 stitch/cm (2 mm), 4 stitch/cm (2.5 mm), thread; sp 60$^{\circ}$s/2, sp 60$^{\circ}$s/3, st 60$^{\circ}$s/3, st 50$^{\circ}$s/3)) by lockstitch industrial sewing machine with shirring foot. The correlations of the easing and sewing conditions were by SPSS PC), and visual test was done by enlarged photo. The results obstained were as follows:. 1. The easing contraction ratio is increased in proportion to the low of stitch density. 2. The easing contraction ratio of wp, 45$^{\circ}$ bias is correlated with stitch density, and that of wf be with stitch density, elongation & weight. 3. The easing contraction ratio of 13 stitch/cm (0.8 mm), 9 stitch/cm (1.1 mm), 6.5 stitch/ cm (1.5 mm), 5 stitch/cm (2.0 mm) is correlated with flexible rigidity, and that of 4 stitch/ cm (2.5 mm) be with flexible rigidity and crease-resistance. 4. As a results of SPSS PC+ statistics, the easing contraction ratio is statistically correlated to the seam line, stitch density, upper thread tension, and fabric characteristics. 5. As a results of visual test by the enlarged photo, the limit of stitch density for easing contraction was 5 stitch/cm (2.0 mm).

• Journal of the Korean Society of Physical Medicine
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• v.8 no.1
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• pp.11-18
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• 2013

PURPOSE: The purpose of this study was to investigate the difference of trunk muscles activity during abdominal hollowing and bracing contraction in various position. METHODS: This pilot test was carried out in a volunteer sample of normal adults(n=24) without a history of low back pain or injury. 24 subjects were randomly allocated to three groups(n=8) as a contraction method respectively. In hooklying position, trunk muscles activity of subjects was measured using EMG in various bridging position. RESULTS: Abdominal bracing contraction made to more great trunk deep and superficial muscles activity than hollowing contraction.(p<0.00) Especially, Multifidus activity was the biggest.(p<0.00) CONCLUSION: The result from this study showed that abdominal bracing contraction made to more balancing activity of trunk muscles than abdominal hollowing contraction. Thus, It will good for trunk muscles unbalanced LBP patient to improve lumbar stabilization.

• Journal of Life Science
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• v.10 no.6
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• pp.584-590
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• 2000

Natural products are one of the useful source of cardiovascular drugs, in particular, when they have antioxidant activity. Gagaminine, an alkaloid isolated from the roots of Cynanchum wilfordi Hemsley, has been reported to potently inhibit the aldehyde oxidase activity ({TEX}$IC_{50}${/TEX}=0.8$\mu$M) and reduce lipid peroxidation. However, the effect of gagaminine on vascular smooth muscle has not yet been investigated. In the present study, we examined whether gagaminine relaxes vascular smooth muscle by isometric tension study. In order to observe its relaxation effect on the arteries, conductivel vessel (rat thoracic aorta) and resistance vessel (pig coronary artery) were purposely used. Results indicated that gagaminine relaxed in a concentration-dependent manner $\alpha$-adrenoceptor agonist, phenylephrine (PE)-induced contraction of rat aorta. Pretreatment with gagaminine inhibited PE-induced contraction, noncompetitively. {TEX}$Ca^{2+}${/TEX}-induced contraction was significantly diminished by gagaminine. In pig coronary artery, gagaminine relaxed thromboxane receptor (U 46619)-mediated contraction in dose-dependent manner. Pretreatment with gagaminine also reduced the maximum contraction induced by KCl. These observations strongly suggest that agagminnine relaxes vascular smooth muscle, irrespective of both resistance and conductive artery. We demonstrate that gagaminine, a potent natural antioxidant, has a significant vasodilatory effect and its action mechanism van be ascribed at least in part to {TEX}$Ca^{2+}${/TEX} antagonistic action as evidenced by inhibition {TEX}$Ca^{2+}${/TEX}-induced contraction (rat aorta) and KCl-induced contraction (porcine artery). Furthermore, neither $\alpha$ -adrenoceptor nor thromboxane receptor seems responsible for the relaxation of gagaminine.

• The Korean Journal of Physiology
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• v.24 no.2
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• pp.353-362
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• 1990

Fluoride (F-), a known stimulator of G-protein, induced strong contraction in rabbit trachealis muscle. $AlCl_3\;(5{\sim}20\;{\mu}M)$, which is required for G-protein stimulation by $F^-$, potentiated the contractile response to $F^-$. $Ca^{2+}-removal$ and verapamil, a calcium channel blocker, inhibited the fluoroaluminate-induced contraction. Fluoroaluminate increased $^{45}Ca$ influx in the absence and presence of verapamil. In heparin-loaded muscle high $K^+-induced$ contraction was not affected, but acetylcholine and fluoroaluminate-induced contractions were inhibited. The fluoroaluminate-induced contraction was partially relaxed by isoproterenol, a stimulator of adenylate cyclase. Pertussis toxin partially inhibited fluoroaluminate-induced contraction and potentiated isoproterenol-induced relaxation in the presence of fluoroaluminate, but had no effect on acetylcholine-induced contraction and the isoproterenol-induced relaxation in the presence of acetylcholine. These results suggest that fluoroaluminate has the ability to stimulate at least two putative G-proteins in rabbit trachealis muscle; One causes $Ca^{2+}$ influx through the potential-operated $Ca^{2+}$ channel and the other induces intracellular $Ca^{2+}$ release by the increase of inositol-1, 4, 5-triphosphate.

• Molecules and Cells
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• v.21 no.1
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• pp.42-51
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• 2006

We investigated the mechanism of contraction induced by S1P in esophageal smooth muscle cells. Western blot analysis demonstrated that $S1P_1$, $S1P_2$, $S1P_3$, and $S1P_5$ receptors existed in the cat esophagus. Only penetration of EDG-5 ($S1P_2$) antibody into permeabilized cells inhibited S1P-induced contraction. Pertussis toxin (PTX) also inhibited contraction, suggesting that it was mediated by $S1P_2$ receptors coupled to a PTXsensitive $G_i$ protein. Specific antibodies to $G_{i2}$, $G_q$ and $G_{\beta}$ inhibited contraction, implying that the S1P-induced contraction depends on PTX-insensitive $G_q$ and $G_{\beta}$ dimers as well as the PTX-sensitive $G_{i2}$. Contraction was not affected by the phospholipase $A_2$ inhibitor DEDA, or the PLD inhibitor ${\rho}$-chloromercuribenzoate, but it was abolished by the PLC inhibitor U73122. Incubation of permeabilized cells with $PLC{\beta}3$ antibody also inhibited contraction. Contraction involved the activation of a PKC pathway since it was affected by GF109203X and chelerythrine. Since $PKC{\varepsilon}$ antibody inhibited contraction, $PKC{\varepsilon}$ may be required. Preincubation of the muscle cells with the MEK inhibitor PD98059 blocked S1P-induced contraction, but the p38 MAP kinase inhibitor SB202190 did not. In addition, co-treatment of cells with GF 109203X and PD98059 did not have a synergistic effect, suggesting that these two kinases are involved in the same signaling pathway. Our data suggest that S1P-induced contraction in esophageal smooth muscle cells is mediated by $S1P_2$ receptors coupled to PTX-sensitive $G_{i2}$ proteins, and PTX-insensitive $G_q$ and $G_{\beta}$ proteins, and that the resulting activation of the $PLC{\beta}3$ and $PKC{\varepsilon}$ pathway leads to activation of a p44/p42 MAPK pathway.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.4
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• pp.87-96
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• 1993

Spectrum analysis of surface electromyogram (FMG) signals is an effective approach to the study of localized muscular fatigue during isometric contraction. Many investigators have con firmed the frequency of the EMG signals being lowered during sustained contaction. In this study, the cyclic loading tasks were performed, and a comparison was made for the median power frequency shift pattern of the EMG signals with the sustained contraction of the same load. The median power frequency shift of the EMG signals for the cyclic loading task was found to be a part of that for the sustained contraction. Based on this result, a new muscle fatigue index was computed by normalizing the duration of the sustained contraction. A fatigue index was obtained as a function of exertion level and the work/rest schedule. With the proposed fatigue index, it is possible to evaluate or predict the degree of muscular fatigue for a physically demanding task.