• The Korean Journal of Physiology and Pharmacology
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• 제2권2호
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• pp.155-163
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• 1998

The purpose of present study was to compare the effects of somatostatin (SOM) and morphine (Mor) on the responses of wide dynamic range (WDR) cells to peripheral noxious stimulation. Single neuronal activity was recorded with a carbon-filament electrode at the lumbosacral enlargement of cat spinal cord. After identifying WDR cells, their responses to peripheral noxious mechanical or thermal stimuli were characterized and the effects of SOM and Mor, applied either iontophoretically or intrathecally, were studied. In most cells SOM and Mor suppressed noxious stimulus-evoked WDR neuronal activity, though a few WDR neurons showed no change or were excited by SOM and Mor. Systemically applied naloxone, a non-specific opioid antagonist, always reversed the Mor induced suppression of neuronal activity evoked by noxious mechanical stimuli, but did not always reverse the suppression of neuronal activity elicited by SOM. The suppressive effect of Mor on thermal stimulus-evoked neuronal activity was partially reversed by naloxone, while that of SOM were not reversed at all. The above results suggest that both Mor and SOM exert an inhibitory effect on thermal and mechanical stimulus-evoked WDR neuronal activity in cat spinal dorsal horn, but the mechanisms are dependent upon the functional populations of dorsal horn nociceptive neurons.

• 한국소음진동공학회논문집
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• 제23권1호
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• pp.9-16
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• 2013

This paper experimentally deals with the excitation by functional electrical stimulus(FES) and the response of electromyo-potential at the muscles of antebrachial joint in a human body. The excitation of FES, which results in the contraction of the muscles and thus the flection of the joint, shows that the flection angle of the joint is proportional to the magnitude of the stimulus current. The response of electromyo-potential measured according to the FES shows the linearly-proportional relation between the joint torque and the electromyo-potential. The results can be used for active motion of joint rehabilitation.

• The Korean Journal of Physiology and Pharmacology
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• 제14권3호
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• pp.169-176
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• 2010

The hyperosmotic stimulus is regarded as a mechanical factor for bone remodeling. However, whether the hyperosmotic stimulus affects $1{\alpha}$, 25-dihydroxyvitamin $D_3$ ($1{\alpha},25(OH)_2D_3$)-induced osteoclastogenesis is not clear. In the present study, the effect of the hyperosmotic stimulus on $1{\alpha},25(OH)_2D_3$-induced osteoclastogenesis was investigated in an osteoblast-preosteoclast co-culture system. Serial doses of sucrose were applied as a mechanical force. These hyperosmotic stimuli significantly evoked a reduced number of $1{\alpha},25(OH)_2D_3$-induced tartrate-resistant acid phosphatase-positive multinucleated cells and $1{\alpha},25(OH)_2D_3$-induced bone-resorbing pit area in a co-culture system. In osteoblastic cells, receptor activator of nuclear factor ${\kappa}B$ ligand (RANKL) and Runx2 expressions were down-regulated in response to $1{\alpha},25(OH)_2D_3$. Knockdown of Runx2 inhibited $1{\alpha},25(OH)_2D_3$-induced RANKL expression in osteoblastic cells. Finally, the hyperosmotic stimulus induced the overexpression of TonEBP in osteoblastic cells. These results suggest that hyperosmolarity leads to the down-regulation of $1{\alpha},25(OH)_2D_3$-induced osteoclastogenesis, suppressing Runx2 and RANKL expression due to the TonEBP overexpression in osteoblastic cells.

• The Korean Journal of Physiology
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• 제23권1호
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• pp.151-167
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• 1989

The present study was undertaken to investigate modification in electrophysiological characteristics of cat dorsal horn cells resulting from carrageenin-induced inflammation. The followings were studied; 1) the time-course of changes in responses of the WDR (wide dynamic range) cell 1-3h after subcutaneous injection of carrageenin in its receptive field; 2) the responses of the same dorsal hern cells before and after induction of inflammation; 3) the effect of inflammation on the responsiveness of dorsal horn neurons to algogens (bradykinin & potassium); and 4) the effect of inflammation on the activity of WDR cell following administration of indomethacin and clonidine. Though responses of WDR neuron were increased dramatically during first 1h, the maximal enhancement was observed 3h after induction of inflammation especially by repetitive light tactile stimulus. Following carrageenin injection the majority of WDR neurons (10/15 units) showed enhanced responses to all the mechanical stimuli while in 3 cases responsiveness were intensified during activation by one tactile stimulus (brush or pressure). One cell was unaffected by inflammation and in another case the response was enhanced only to noxious stimulus. Five of 9 cells that could initially be driven by noxious stimulus were activated more strongly by same stimulus and even by tactile stimulus (pressure) following inflammation. In 2 cases neurons were sensitized only to noxious stimulus whereas in another 2 cells that did not show enhanced responses to noxious stimulus responses to light tactile stimulus (pressure) appeared after inflammation. Of 16 LT cells tested 6 responded to squeeze while 4 showed the characteristics of WDR cell following inflammation. No modification in responsiveness was recognized in 3 cells whereas response to only brush was enhanced in another 3 neurons. Following carrageenin injection responses of LT cell to bradykinin or $K^{+}$ were not altered whereas those of WOR neurons to bradykinin or $K^{+}$ were suppressed in 22.2% and 33.3% of cases, respectively. In two of 8 activity of HT cells were inhibited by bradykinin while in five of 8 responsiveness to $K^{+}$ were rather enhanced by inflammation. In the rest inflammation was ineffective. In inflammation-induced animal the receptive field of LT cell was not changed whereas those of WDR cell and HT cell were tremendously expanded. The enhanced responses of WDR neurons to mechanical stimuli resulted from inflammation were suppressed by intravenously injected indomethacin and clonidine suggesting that postaglandin is involved in inflammation-induced sensitization of these cells. The involvement of peripheral and central mechanisms in the modification in responsiveness of dorsal horn cells in the carrageenin-induced inflammation was discussed.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1103-1109
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• 2003

An adaptive bone remodeling is simulated by using the cellular automata (CA) method. It is assumed that bone tissue consist of bone marrow, osteoclast, osteoblast cell or osteoprogenitor cell. Two types of local rule are adopted; those are the metabolism rule and adaptive bone formation rule. The metabolism rule is based on the interactions of cells and the bone formation rule is based on the adaptation against the mechanical stimulus. The history of load and memory of mechanical stimulus are also considered in the local rules. As a result, the pattern of distribution of the bone tissue is dynamically adequate and it is similar to intact cancellous bone.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.429-438
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• 1994

An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate eleclromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocnemius m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher'stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical slimulator restored partially gait function in paraplegic patients.

• 한국정보전자통신기술학회논문지
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• 제1권3호
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• pp.27-32
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• 2008

뼈가 왜 고주파 미세자극(low amplitude and high frequency)에 반응하는가를 진동의 공명현상(resonance)을 이용하여 접근해 보았다. 예를 들면 30Hz, $5{\mu}{\epsilon}$ 정도의 진동이 뼈 내 골수 간질액 (bone fluid)의 흐름을 주관하는 미세관(canaliculus) 내벽에 작용할 경우 빔 형태의 구조물들로 연결되어 있는 골세포돌기 세포막 (osteocytic process membrane)은 공명현상에 의해서 $1,000{\mu}{\epsilon}$ 이상으로 증폭된다. 이 결과는 사전조사 형태에 속하며, 향후 (1) 세포실험을 통하여 세포내 신호전달체계변화를 분자생물학적인 방법으로, 그리고 (2) 세포내 골격계에 해당하는 액틴필라멘트의 변화를 공초점 주사 레이져 현미경 (Confocal Laser Scanning Microscope)등의 영상기기의 사용으로 관찰하려고 한다.

• 대한의용생체공학회:의공학회지
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• 제10권2호
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• pp.109-111
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• 1989

An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate electromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocneminus m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical stimulator restored partially gait function in paraplegic patients.

• 한국가시화정보학회지
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• 제13권2호
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• pp.22-27
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• 2015

Caenorhabditis elegans (C.elegans) has various interesting behavioral properties, such as chemotaxis, thermotaxis, and electrotaxis. However, most previous research were only focused on single-stimulus for studying its behavioral properties. In this paper, we propose a simple and effective device for analyzing the behavior of C.elegans with combined stimuli, electric field and temperature. We compared and analyzed wild type worms (N2) and four mutant worms (tax-4, ttx-7, unc-54, unc-6). We analyzed the reaction of worms to certain stimulus and identified that this device is effective to apply a combined stimulus.

• 접착 및 계면
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• 제21권4호
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• pp.162-167
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• 2020

피부 모사형 다기능 유연 센서는 인체 피부의 높은 자극 감지 성능과 기계적 안정성을 모사하고자 다학계적 접근을 통해 발전되어 왔다. 하지만, 실제 적용을 위해서는 일상생활 속에서 접하는 다양한 종류의 자극을 명확히 구분하고 각 자극의 세기를 정확히 감지하는 높은 수준의 자극 구별 능력이 필수적임에도 불구하고, 아직까지 낮은 수준의 자극 구별 능력을 보이는 실정이다. 본고에서는 기존 피부 모사형 유연 센서의 기본적인 작동 메커니즘과 대표적인 연구들을 간략히 소개하고, 최근 보고된 피부 모사형 다기능 유연 센서 관련 연구들의 연구 결과 및 자극 구별 능력에 대해 깊이 있게 다루고자 한다.