• Title/Summary/Keyword: Contraction factor

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A Comparison of Muscle Contraction Using Functional Electrical Stimulation: Intermittent High Frequency Alternating Stimulation Versus Intermittent Low Frequency Synchronous Stimulation (기능적 전기자극기를 이용한 간헐적 고주파 교대자극과 간헐적 저주파 동시자극의 근 수축력 비교)

  • Song, Young-Hee;Cho, Sang-Hyun;Lee, Young-Hee
    • Physical Therapy Korea
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    • v.9 no.2
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    • pp.115-131
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    • 2002
  • Functional electrical stimulation (FES) training of the knee extensors is a useful way to rehabilitate the ability to stand and walk. However, training using FES has not been able to solve the problem of fatigue; clinical application of FES quickly produces muscle fatigue, due to the continuous activation of the muscles of the lower extremity. Therefore, reduction of muscle fatigue is an important factor in increasing the effectiveness of FES training in paraplegia. Intermittent high frequency alternating stimulation is a method that combines the advantages of high frequency (leading to strong muscle contractions) and alternating stimulation (reducing muscle fatigue), thereby continuously strengthening muscles. It is not known whether low frequency simultaneous stimulation results in stronger muscle contraction than high frequency alternating stimulation. This study compared the effectiveness of high frequency alternating stimulation with low frequency synchronized stimulation. Muscle power using FES on the quadriceps of 20 normal subjects were compared. Intermittent high frequency alternating stimulation did not produce more powerful muscle contraction than intermittent low frequency synchronized stimulation, because the muscle characteristics differed individually. Significant individual variation according to muscle characteristics was founded when applying FES. Accordingly, when physical therapists use FES to treat patients, they must be aware of individual variation in muscle characteristics.

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Glucosamine increases vascular contraction through activation of RhoA/Rho kinase pathway in isolated rat aorta

  • Kim, Do-Hyung;Seok, Young-Mi;Kim, In-Kyeom;Lee, In-Kyu;Jeong, Seong-Yun;Jeoung, Nam-Ho
    • BMB Reports
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    • v.44 no.6
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    • pp.415-420
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    • 2011
  • Diabetes is a well-known independent risk factor for vascular disease. However, its underlying mechanism remains unclear. It has been reported that increased influx of the hexosamine biosynthesis pathway (HBP) induces O-GlcNAcylation of proteins, leading to insulin resistance. In this study, we determined whether or not O-GlcNAc modification of proteins could increase vessel contraction. Using an endothelium-denuded aortic ring, we observed that glucosamine induced OGlcNAcylation of proteins and augmented vessel contraction stimulated by U46619, a thromboxane $A_2$ agonist, via augmentation of the phosphorylation of MLC20$MLC_{20}$, MYPT1(Thr855), and CPI17, but not phenylephrine. Pretreatment with OGT inhibitor significantly ameliorated glucosamine-induced vessel constriction. Glucosamine treatment also increased RhoA activity, which was also attenuated by OGT inhibitor. In conclusion, glucosamine, a product of glucose influx via the HBP in a diabetic state, increases vascular contraction, at least in part, through activation of the RhoA/Rho kinase pathway, which may be due to O-GlcNAcylation.

A Rule Extraction Method Using Relevance Factor for FMM Neural Networks (FMM 신경망에서 연관도요소를 이용한 규칙 추출 기법)

  • Lee, Seung Kang;Lee, Jae Hyuk;Kim, Ho Joon
    • KIPS Transactions on Software and Data Engineering
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    • v.2 no.5
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    • pp.341-346
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    • 2013
  • In this paper, we propose a rule extraction method using a modified Fuzzy Min-Max (FMM) neural network. The suggested method supplements the hyperbox definition with a frequency factor of feature values in the learning data set. We have defined a relevance factor between features and pattern classes. The proposed model can solve the ambiguity problem without using the overlapping test process and the contraction process. The hyperbox membership function based on the fuzzy partitions is defined for each dimension of a pattern class. The weight values are trained by the feature range and the frequency of feature values. The excitatory features and the inhibitory features can be classified by the proposed method and they can be used for the rule generation process. From the experiments of sign language recognition, the proposed method is evaluated empirically.

Local Silencing of Connective Tissue Growth Factor by siRNA/Peptide Improves Dermal Collagen Arrangements

  • Cho Lee, Ae-Ri;Woo, Inhae
    • Tissue Engineering and Regenerative Medicine
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    • v.15 no.6
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    • pp.711-719
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    • 2018
  • BACKGROUND: Collagen organization within tissues has a critical role in wound regeneration. Collagen fibril diameter, arrangements and maturity between connective tissue growth factor (CTGF) small interfering RNA (siRNA) and mismatch scrambled siRNA-treated wound were compared to evaluate the efficacy of CTGF siRNA as a future implement for scar preventive medicine. METHODS: Nanocomplexes of CTGF small interfering RNA (CTGF siRNA) with cell penetrating peptides (KALA and $MPG^{{\Delta}NLS}$) were formulated and their effects on CTGF downregulation, collagen fibril diameter and arrangement were investigated. Various ratios of CTGF siRNA and peptide complexes were prepared and down-regulation were evaluated by immunoblot analysis. Control and CTGF siRNA modified cells-populated collagen lattices were prepared and rates of contraction measured. Collagen organization in rabbit ear 8 mm biopsy punch wound at 1 day to 8 wks post injury time were investigated by transmission electron microscopy and histology was investigated with Olympus System and TS-Auto software. CONCLUSION: CTGF expression was down-regulated to 40% of control by CTGF siRNA/KALA (1:24) complexes (p<0.01) and collagen lattice contraction was inhibited. However, down-regulated of CTGF by CTGF $siRNA/MPG^{{\Delta}NLS}$ complexes was not statistically significant. CTGF KALA-treated wound appeared with well formed-basket weave pattern of collagen fibrils with mean diameter of $128{\pm}22nm$ (n = 821). Mismatch siRNA/KALA-treated wound showed a high frequency of parallel small diameter fibrils (mean $90{\pm}20nm$, n = 563). CONCLUSION: Controlling over-expression of CTGF by peptide-mediated siRNA delivery could improve the collagen orientation and tissue remodeling in full thickness rabbit ear wound.

A Casuistics of a Patient with Facial Palsy and Paralytic Strabismus (안면신경마비와 마비성 사시를 병발한 환자의 증례보고)

  • Cho, Jae-Hun;Kim, Yoon-Bum;Chae, Byung-Yoon
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.13 no.2
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    • pp.152-164
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    • 2000
  • 1. We experienced one case with facial palsy and paralytic strabismus, which improved under the treatment of Acupuncture, Infrared, Electroacupuncture and Massage. 2. The prognostic factor of facial palsy was affected by On Set and neurodegeneration (such as synkinesis, contraction, spasm and crocodile tear). 3. In facial palsy, Myoneural Excitability Test by Electroacupuncture, which will need the objective clinical standard, was available for the evaluation of therapeutic effect and prognosis.

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Effect of forearm length applied on empirical models of maximum endurance time during isometric elbow flexion (등척성 팔굽 굽힘시 최대근지구력시간의 실증적 모델에 적용한 전완길이의 영향)

  • Sang-Sik Lee;Kiyoung Lee
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.16 no.5
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    • pp.338-346
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    • 2023
  • During isometric elbow flexion, forearm length should be an important factor to determine not only joint torque but also maximum endurance time (MET), when the forearm is perpendicular to the direction of the force. The purpose of this paper is to examine the effect of forearm length as an additional factor on empirical models of MET such as an exponential model and a power model during isometric elbow flexion. Thirty volunteers participated in our experiment to measure factor variables such as circumferences and lengths of their upper and lower arms. Their METs were measured according to the percent of maximum voluntary contraction intensity (%MVC). For the multiple linear regression model of ln(MET) using these measurements, significant variables could be observed in %MVC and forearm lengths (P<0.05). The empirical models were assessed by these models using forearm length as the additional factor. Mean absolute deviations (MAD) between the measured METs amd the two empirical models were about 19.4 [s], but MAD using models applied forearm lengths were reduced to about 16.2 [s]. The correlation coefficients and intraclass correlation coefficients were about 0.87, but those applied forearm lengths were increased to about 0.91. These results demonstrated that forearm length was a significant additional factor to the empirical model.

The Absence of Atrial Contraction as a Predictor of Permanent Pacemaker Implantation after Maze Procedure with Cryoablation

  • Jeon, Chang-Seok;Shim, Man-shik;Park, Seung-Jung;Jeong, Dong Seop;Park, Kyoung-Min;On, Young Keun;Kim, June Soo;Park, Pyo Won
    • Journal of Chest Surgery
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    • v.50 no.3
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    • pp.163-170
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    • 2017
  • Background: The absence of atrial contraction (AC) after the maze procedure has been reported to cause subsequent annular dilatation and to increase the risk of embolic stroke. We hypothesized that the lack of AC could increase the risk of permanent pacemaker (PPM) implantation in patients undergoing the maze procedure. Methods: In 376 consecutive patients who had undergone a cryo-maze procedure and combined valve operation, recovery of AC was assessed at baseline and at immediate (${\leq}2$ weeks), early (${\leq}1$ year, $4.6{\pm}3.8$ months), and late (>1 year, $3.5{\pm}1.1$ years) postoperative stages. Results: With a median follow-up of 53 months, 10 patients underwent PPM implantation. Seven PPM implants were for sinus node dysfunction (pauses of $9.6{\pm}2.4$ seconds), one was for marked sinus bradycardia, and two were for advanced/complete atrioventricular block. The median (interquartile range) time to PPM implantation was 13.8 (0.5-68.2) months. Our time-varying covariate Cox models showed that the absence of AC was a risk factor for PPM implantation (hazard ratio, 11.92; 95% confidence interval, 2.52 to 56.45; p=0.002). Conclusion: The absence of AC may be associated with a subsequent risk of PPM implantation.

Ultrasound Imaging and Electrophysiological Characteristic According to Activity Levels of Myofascial Trigger Point (근근막 발통점의 활성도에 따른 초음파 영상구조 및 전기생리학적 특성)

  • Kim, Hyun-Jin;Kim, Su-Hyun;Park, Young-Hyun;Oh, Seok;Choi, Ji-Ho;Kim, Tae-Youl
    • Journal of the Korean Academy of Clinical Electrophysiology
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    • v.8 no.1
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    • pp.23-29
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    • 2010
  • Purpose : This study is to offer clinical primary data that examines the change of imaging structure and the quantitative evaluation of muscle activity on myofascial trigger points. This study examines neuromuscular physiological characteristic by comparing the differences in physical findings, pressure pain threshold, imaging, and electrophysiological characteristics in latent and active myofascial trigger points muscle and normal muscle through the following experimental procedures. Methods : The participants for the study were thirty-three adults in their twenties. We divided three groups into normal, latent and active myofascial trigger points groups by physical findings. We analyzed the results of measured pressure pain, threshold for pain, ultrasound imaging perform for structure characteristic of muscle, surface EMG according to type of muscle contraction for function of muscle contraction. Results : Significant differences were indicated in pressure pain threshold (p<0.05). Significant differences were discovered in the ultrasound imaging analysis. There were increases in muscle Echogenicity white area index (p<0.001). There were significant differences that decrease in %MVIC (p<0.05), increase in MDF (p<0.05). Conclusion : From these results, active rnyotascial trigger points muscle showed quality deterioration on ultrasound imaging and decreased function of muscle contraction, increased motor unit action potential of II type fiber, and electrophysiologically. Imaging structure and neuromuscular physiological characteristic can be diagnostic and quantitative analytical techniques for myofascial pain syndrome and a primary factor that reflected in physical therapy intervention.

Characteristics of Multipath Ultrasonic Flowmeter Installed Upstream and Downstream of Flow Disturbance Factors-Contraction, Expansion, and Tee Pipe (유동교란인자(축소·확대관, Tee관)상하류에 설치된 다회선초음파 유량계의 특성)

  • Lee, Dong-Keun;Cho, Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.8
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    • pp.877-883
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    • 2012
  • Multipath ultrasonic flowmeters are increasingly being used for the purpose of accurate flow measurement. However, an installation standard has not yet been established for these flowmeters, and this can cause considerable confusion during field installation. There is a need for a minimum straight run to ensure the measurement accuracy of a flowmeter installed upstream and downstream of flow disturbance factors-expansion, contraction, and tee pipes. Experiments were performed by using multipath flowmeters that have less than ${\pm}0.5%$ accuracy-4-paths 1-unit and 2-paths 1-unit are of foreign make, whereas 5-paths 2-units are of domestic make-to determine the straight run under the above conditions. We carried out experiments repeatedly by considering a straight run, velocity, and suggested installation standards for a multipath ultrasonic flowmeter that satisfies the tolerance limits.

Estrogen modulates serotonin effects on vasoconstriction through Src inhibition

  • Kim, Jae Gon;Leem, Young-Eun;Kwon, Ilmin;Kang, Jong-Sun;Bae, Young Min;Cho, Hana
    • Experimental and Molecular Medicine
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    • v.50 no.12
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    • pp.11.1-11.9
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    • 2018
  • Estrogen has diverse effects on cardiovascular function, including regulation of the contractile response to vasoactive substances such as serotonin. The serotonin system recently emerged as an important player in the regulation of vascular tone in humans. However, hyperreactivity to serotonin appears to be a critical factor for the pathophysiology of hypertension. In this study, we examined the modulatory mechanisms of estrogen in serotonin-induced vasoconstriction by using a combinatory approach of isometric tension measurements, molecular biology, and patch-clamp techniques. $17{\beta}$-Estradiol (E2) elicited a significant and concentration-dependent relaxation of serotonin-induced contraction in deendothelialized aortic strips isolated from male rats. E2 triggered a relaxation of serotonin-induced contraction even in the presence of tamoxifen, an estrogen receptor antagonist, suggesting that E2-induced changes are not mediated by estrogen receptor. Patch-clamp studies in rat arterial myocytes showed that E2 prevented Kv channel inhibition induced by serotonin. Serotonin increased Src activation in arterial smooth muscle required for contraction, which was significantly inhibited by E2. The estrogen receptor-independent inhibition of Src by E2 was confirmed in HEK293T cells that do not express estrogen receptor. Taken together, these results suggest that estrogen exerts vasodilatory effects on serotonin-precontracted arteries via Src, implying a critical role for estrogen in the prevention of vascular hyperreactivity to serotonin.