• 제목/요약/키워드: Contraction force

검색결과 275건 처리시간 0.023초

Die spacer의 두께에 따른 복합레진 inlay의 치은 변연부 미세누출 및 접착양태에 관한 연구 (GINGIVAL MARGIAL LEAKAGE AND BONDING PATTERN OF THE COMPOSITE RESIN INLAY ACCORDING TO VARIOUS THICKNESS OF DIE SPACER)

  • 박태일;신동훈;홍찬의
    • Restorative Dentistry and Endodontics
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    • 제20권1호
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    • pp.152-163
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    • 1995
  • This experiment was performed to observe the adhesion pattern and microleakage in the gingival margin according to variation in the resin cement thickness which results from thickness of Die spacer. which is considered to effect the adaptability of the composite resin inlays. Clearfil CR inlays were fabricated on stone models with CR Sep applicated once and Nice fit twice, 4 times, and 6 times each. After 2nd curing within the CRC-100 oven, CR inlays were cemented with CR inlay cement. Dye(2% methylene blue) penetration and adhesion pattern were evaluated after sectioning of gingival margin into :3 pieces. The results were as follows ; 1. The thickness of resin cement showed unevenchanging pattern with that of die spacer, namely, it was increased until 4 times' application of Nice-Fit but was decreased with 6 times' application of that. 2. The degree of dye penetration wasn't affected by cement thickness within a limited value. 3. Most of dye penetration was shown through the interface between cement and enamel rather than the interface between cement and CR inlay. This shows that the affinity of resin cement for CR inlay was superior to the adhesive strength with tooth structure. 4. No gap was found at the interface between enamel and cement but some showed separation between dentin and cement. It is concidered that the contraction force of cement was less than the bond strength with the enamel. 5. Lots of voids were found in the CR inlay and resin cement. There was a pooling tendency of bonding agent and cement in the axiogingival line angle portion. 6. In some specimens, cracks were shown in enamel margin. From this it could be considered that cavity preparation and surface treatment weakened the tooth structure.

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Neuroprotective Effect of Visnagin on Kainic Acid-induced Neuronal Cell Death in the Mice Hippocampus

  • Kwon, Min-Soo;Lee, Jin-Koo;Park, Soo-Hyun;Sim, Yun-Beom;Jung, Jun-Sub;Won, Moo-Ho;Kim, Seon-Mi;Suh, Hong-Won
    • The Korean Journal of Physiology and Pharmacology
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    • 제14권5호
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    • pp.257-263
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    • 2010
  • Visnagin (4-methoxy-7-methyl-5H-furo[3,2-g][1]-benzopyran-5-one), which is an active principle extracted from the fruits of Ammi visnaga, has been used as a treatment for low blood-pressure and blocked blood vessel contraction by inhibition of calcium influx into blood cells. However, the neuroprotective effect of visnagin was not clearly known until now. Thus, we investigated whether visnagin has a neuroprotective effect against kainic acid (KA)-induced neuronal cell death. In the cresyl violet staining, pre-treatment or post-treatment visnagin (100 mg/kg, p.o. or i.p.) showed a neuroprotective effect on KA ($0.1{\mu}g$) toxicity. KA-induced gliosis and proinflammatory marker (IL-$1{\beta}$, TNF-${\alpha}$, IL-6, and COX-2) inductions were also suppressed by visnagin administration. These results suggest that visnagin has a neuroprotective effect in terms of suppressing KA-induced pathogenesis in the brain, and that these neuroprotective effects are associated with its anti-inflammatory effects.

인삼(人蔘)이 백서심장(白鼠心臟)의 cyclic AMP함량(含量) 변화(變化)에 미치는 영향(影響)에 관(關)한 연구(硏究) (Study on the Effect of Ginseng on the cyclic AMP Content in the Rat Hearts)

  • 김낙두;차수만
    • 생약학회지
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    • 제13권4호
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    • pp.137-144
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    • 1982
  • It was previously reported from our laboratory that the rate of deterioration of the force of contraction was slower in heart from Panax ginseng extract treated rats. The study carried out to elucidate its mechanism of the action on hearts. The cyclic AMP content in the rat hearts was measured by the method of radioimmunoassay techniques. Panax ginseng extract (100mg/kg/day) was administered orally to male Sprague-Dawley rats weighing 150g to 250g for 1 week and after 24 hrs the hearts were isolated and the cyclic AMP content in the fresh heart was assayed. The difference in cyclic AMP content between the rats treated with Panax ginseng extracts and normal rats was not significant. Panax ginseng extract(l00mg/kg/day) was administered orally to the rats for I week and after 24 hrs the hearts were isolated and perfused with Krebs-Henseleit buffer (pH7.4) for 90min. The cyclic AMP content in the both treated and normal rats was not also significantly different. On the other hand, when total ginseng saponin (50mg/kg/day) was administered orally to rats for 1 week and after 24 hrs, the isolated hearts were perfused with Krebs Henseleit solution for 32min, the cyclic AMP content in total ginseng soponin treated hearts was decreased by 18.7% compared to normal rats. It was also observed that when isolated hearts were perfused with total ginseng saponin $(10^{-4}g/ml)$ for 12 min after 30 min equilibration period, the cyclic AMP content in total ginseng saponin treated hearts was decreased by 23.7% compared to normal rats. Isolated hearts were perfused with ginseng saponins $(10^{-4}g/ml)$ or with Krebs-Henseleit solution alone for 10min and subsequently with dl-isoproterenol $(1/2{\times}10^{-6}M)$ until the positive inotropic effect of isoproterenol was initiated. The cyclic AMP content in each rat hearts treated with total ginseng saponin, or with ginsenoside $Rb_1$, or with Krebs-Henseleit solution alone were increased by 35.5%, 42.4%, 47.5%, respectively, compared to normal rats.

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로봇 손용 인체모방형 구동기 및 센서 (Biomimetic Actuator and Sensor for Robot Hand)

  • 김백철;정진아;조한정;신승훈;이형석;문형필;최혁렬;구자춘
    • 대한기계학회논문집A
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    • 제36권12호
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    • pp.1497-1502
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    • 2012
  • 복잡한 구조와 다채로운 기능을 수행하는 사람 손의 기능을 모사하는 로봇 손을 제작함에 있어서 유연성 있는 구동기와 센서의 개발이 필수적으로 요구되고 있다. 본 논문에서는 전기활성 고분자를 기반으로 하여 로봇 손에 사용될 수 있는 구동기와 슬립센서의 설계, 제작 및 성능검증에 대한 내용을 소개한다. 전기활성 고분자는 필름형태로 제작되며 양단에 전압을 가하여 수축과 팽창에 따른 움직임이 발생하게 한다. 이와 반대로 전기활성 고분자에 외부의 압력으로 인해 두께나 면적의 변화가 발생하게 되면 정전용량의 변화가 발생하게 된다. 이러한 에너지의 변화소자를 이용하여 구동기와 센서로 이용하였다. 본 논문에서는 전기활성 고분자를 이용한 구동기와 센서를 제시하고 성능평가를 통해 새로운 로봇 손용 에너지 변환 소자로서의 가능성을 연구하였다.

Characteristics of Hypoxic Pulmonary Vasoconstriction of the Rat: Study by the Vessel Size and Location in the Lung

  • Lee, Sang-Jin;Kim, Ki-Whan
    • The Korean Journal of Physiology and Pharmacology
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    • 제3권3호
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    • pp.321-328
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    • 1999
  • Pulmonary blood vessels with diameters of $200{\sim}400\;{\mu}m$ produce considerably more force in response to vasoconstrictor drugs than those which are either smaller or larger. We have therefore investigated whether or not hypoxic pulmonary vasoconstriction (HPV) is more powerful in vessels of these diameters. We have also looked at the possibility that vessels from different regions of the lung respond differently. To do this we have grouped vessels according to their location within the lung as well as by size. We used a small vessel myograph (Cambustion AM10, Cambridge, UK) to study 208 preconstricted $(1\;{\mu}M\;PGF_{2{\alpha}})$ small pulmonary arteries $(300{\sim}800\;{\mu}m$ diameter when stretched to a tension equivalent to 25 mmHg transmural pressure) from 39 rats anaesthetized with 2% inspired halothane. A biphasic contraction was observed in response to hypoxia (ca. 25 mmHg $Po_2).$ The magnitudes of both the first, transient, phase (PT, peak tension) and of the second, sustained, phase (SST, steady state tension) were measured. The latter was measured 40 min after the start of hypoxia. The first phase was most pronounced in vessels with an average diameter of 423 ${\mu}m$ while the second phase was most pronounced in larger vessels (mean diameter 505 ${\mu}m).$ These maximal responses were all seen in vessels somewhat larger than reported by others. The responses of smaller vessels $(400{\sim}500\;{\mu}m)$ did not depend upon their location within the lung, but those of larger vessels $(600{\sim}700\;{\mu}m)$ showed regional differences. Those from the right lobe and those from the base of the lung gave the largest responses. It was especially noticeable that large vessels (631 ${\mu}m$ diameter) from the base of the right lung gave the biggest responses. Thus HPV seems to occur not in a uniform manner, dependent solely to the size of vessels, but it also depends to some degree on the region of the lung from which vessels have been taken. Furthermore, our results suggest that larger vessels, as well as smaller ones, may contribute significantly to HPV.

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Myoplasmic [$Ca^{2+}$], Crossbridge Phosphorylation and Latch in Rabbit Bladder Smooth Muscle

  • Kim, Young-Don;Cho, Min-Hyung;Kwon, Seong-Chun
    • The Korean Journal of Physiology and Pharmacology
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    • 제15권3호
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    • pp.171-177
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    • 2011
  • Tonic smooth muscle exhibit the latch phenomenon: high force at low myosin regulatory light chains (MRLC) phosphorylation, shortening velocity (Vo), and energy consumption. However, the kinetics of MRLC phosphorylation and cellular activation in phasic smooth muscle are unknown. The present study was to determine whether $Ca^{2+}$-stimulated MRLC phosphorylation could suffice to explain the agonist- or high $K^+$-induced contraction in a fast, phasic smooth muscle. We measured myoplasmic [$Ca^{2+}$], MRLC phosphorylation, half-time after step-shortening (a measure of Vo) and contractile stress in rabbit urinary bladder strips. High $K^+$-induced contractions were phasic at both $22^{\circ}C$ and $37^{\circ}C$: myoplasmic [$Ca^{2+}$], MRLC phosphorylation, 1/half-time, and contractile stress increased transiently and then all decreased to intermediate values. Carbachol (CCh)-induced contractions exhibited latch at $37^{\circ}C$: stress was maintained at high levels despite decreasing myoplasmic [$Ca^{2+}$], MRLC phosphorylation, and 1/half-time. At $22^{\circ}C$ CCh induced sustained elevations in all parameters. 1/half-time depended on both myoplasmic [$Ca^{2+}$] and MRLC phosphorylation. The steady-state dependence of stress on MRLC phosphorylation was very steep at $37^{\circ}C$ in the CCh- or $K^+$-depolarized tissue and reduced temperature flattend the dependence of stress on MRLC phosphorylation compared to $37^{\circ}C$. These data suggest that phasic smooth muscle also exhibits latch behavior and latch is less prominent at lower temperature.

팬터그래프와 전차선간 최소 이선아크 지속시간에 따른 이선율 변화량 분석 (Analysis of Percentage of Arcing between Pantograph and Overhead Contact Line as a Function of Duration of Arc)

  • 박영;이기원;권삼영;박철민;김재광;최원석
    • 전기학회논문지
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    • 제63권6호
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    • pp.855-859
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    • 2014
  • Quality criteria for interaction between a pantograph and overhead contact wire is a most important requirement to assess of the performance for the current collection system. Interaction performance between pantograph and catenary system is subject to approval by the infrastructure manager when a new design and contraction of overhead contact line and pantograph are installed. Among the various performance, percentage of arcing at maximum line speed is a simple test method compared with contact force of pantograph due to direct sensing of pantagraph, calibrations, installations of train, and etc. On the other hand, percentage of arcing is need to reliable arcing detector and general requirements with accordance with EN 50317. In this paper, percentage of arcing are investigated on the function of duration of arc and proposed which is satiable of percentage of arcing. As a results, we proposed which duration of arcs are unsuitable from infrastructures point of view as performance testing for quality of current collection.

칼슘 및 칼륨이온이 흰쥐 자궁근(子宮筋) 활동전압(活動電壓)에 미치는 영향(影響) (Effects of $Ca^{2+}$ and $K^+$ on the Spike Action Potentials in Oxytocin-induced Uterine Contractions)

  • 김철수;김기환
    • The Korean Journal of Physiology
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    • 제20권1호
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    • pp.43-52
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    • 1986
  • The influences of extracellular $Ca^{2+}\;and\;K^+$ upon the spike action potentials were studied in isolated uterine strips of rat. Regular, rhythmic uterine contractions were induced by the administration of oxytocin$(0.2{\sim}0.5\;I.U.)$, and recorded with force transducer. Spike action potentials were extracellularly measured by use of suction electrode, and compared with those recorded intracellularly by glass microelectrode. The results obtained were as follows : 1) The frequency and duration of spike bursts, and the number of spikes in a burst could be analyzed by use of both methods. But the absolute values of membrane potential were not measurable with the suction electrode. 2) The duration of contraction$(CD_{90};\;the\;duration\;of\;90%\;relaxation)$ was lengthened from the control 17.0 sec to 20.6 sec, in parallel with the increase of spike number from the control 21 to 26, as the increase in $Ca^{2+}$ concentration from 2 to 4 mM. 3) The amplitude and frequency of contractions were gradually decreased, simultaneously with the decrease in the number of spikes in a burst, when the $Ca^{2+}-antagonist$, verapamil was administered cumulatively. 4) The number of spikes was changed from the control 15 to 7, in cabs of the administration of ver)'low dose of verapamil$(10^{-6}\;g/l)$. 5) Increase in the numbers of spike bursts was well matched to the increase in frequency of contractions when extracellular $K^+$ was increased.

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Dexmedetomidine inhibits vasoconstriction via activation of endothelial nitric oxide synthase

  • Nong, Lidan;Ma, Jue;Zhang, Guangyan;Deng, Chunyu;Mao, Songsong;Li, Haifeng;Cui, Jianxiu
    • The Korean Journal of Physiology and Pharmacology
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    • 제20권5호
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    • pp.441-447
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    • 2016
  • Despite the complex vascular effects of dexmedetomidine (DEX), its actions on human pulmonary resistance arteries remain unknown. The present study tested the hypothesis that DEX inhibits vascular tension in human pulmonary arteries through the endothelial nitric oxide synthase (eNOS) mediated production of nitric oxide (NO). Pulmonary artery segments were obtained from 62 patients who underwent lung resection. The direct effects of DEX on human pulmonary artery tension and changes in vascular tension were determined by isometric force measurements recorded on a myograph. Arterial contractions caused by increasing concentrations of serotonin with DEX in the presence or absence of L-NAME (endothelial nitric oxide synthase inhibitor), yohimbine (${\alpha}_2$-adrenoceptor antagonist) and indomethacin (cyclooxygenase inhibitor) as antagonists were also measured. DEX had no effect on endothelium-intact pulmonary arteries, whereas at concentrations of $10^{-8}{\sim}10^{-6}mol/L$, it elicited contractions in endothelium-denuded pulmonary arteries. DEX (0.3, 1, or $3{\times}10^{-9}mmol/L$) inhibited serotonin-induced contraction in arteries with intact endothelium in a dose-dependent manner. L-NAME and yohimbine abolished DEX-induced inhibition, whereas indomethacin had no effect. No inhibitory effect was observed in endothelium-denuded pulmonary arteries. DEX-induced inhibition of vasoconstriction in human pulmonary arteries is mediated by NO production induced by the activation of endothelial ${\alpha}_2$-adrenoceptor and nitric oxide synthase.

Mechanisms of Motility Change on Trinitrobenzenesulfonic Acid-Induced Colonic Inflammation in Mice

  • Cheon, Gab Jin;Cui, Yuan;Yeon, Dong-Soo;Kwon, Seong-Chun;Park, Byong-Gon
    • The Korean Journal of Physiology and Pharmacology
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    • 제16권6호
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    • pp.437-446
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    • 2012
  • Ulcerative colitis is an inflammatory bowel disease (IBD) characterized by recurrent episodes of colonic inflammation and tissue degeneration in human or animal models. The contractile force generated by the smooth muscle is significantly attenuated, resulting in altered motility leading to diarrhea or constipation in IBD. The aim of this study is to clarify the altered contractility of circular and longitudinal smooth muscle layers in proximal colon of trinitrobenzen sulfonic acid (TNBS)-induced colitis mouse. Colitis was induced by direct injection of TNBS (120 mg/kg, 50% ethanol) in proximal colon of ICR mouse using a 30 G needle anesthetized with ketamin (50 mg/kg), whereas animals in the control group were injected of 50% ethanol alone. In TNBS-induced colitis, the wall of the proximal colon is diffusely thickened with loss of haustration, and showed mucosal and mucular edema with inflammatory infiltration. The colonic inflammation is significantly induced the reduction of colonic contractile activity including spontaneous contractile activity, depolarization-induced contractility, and muscarinic acetylcholine receptor-mediated contractile response in circular muscle layer compared to the longitudinal muscle layer. The inward rectification of currents, especially, important to $Ca^{2+}$ and $Na^+$ influx-induced depolarization and contraction, was markedly reduced in the TNBS-induced colitis compared to the control. The muscarinic acetylcholine-mediated contractile responses were significantly attenuated in the circular and longitudinal smooth muscle strips induced by the reduction of membrane expression of canonical transient receptor potential (TRPC) channel isoforms from the proximal colon of the TNBS-induced colitis mouse than the control.