• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1674-1678
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• 2008

본 연구에서는 심장의 세포 변화에서부터 혈류 순환의 시스템 변화까지 일련의 과정을 시뮬레이션 할 수 있는 통합모델을 개발하였다. 본 통합 모델을 이용하여 대동맥의 탄성도 변화 따른 Pulse Wave Velocity를 추정하였으며 심근의 수축 Mechanics의 변화를 시뮬레이션 하였다. 심장은 단순한 구 형상으로 모델링 되었다. 특히 동맥순환의 특성인 Wave propagation 과 Wave deflection의 현상을 모델링하기 위해 기존 모델에서 사용된 동맥계 순환 모델을 수정하였다. 즉 기존의 동맥 모델을 1차원의 운동방정식과 연속방정식을 기반으로 하는 Distributed arterial model로 대체하였다. Distributed arterial model은 혈액의 점성에 의한 에너지 손실, 혈관의 점탄성 효과 그리고 분지 되는 혈관에서의 에너지 손실을 포함하는 정교한 동맥 순환 모델이다. 정교한 동맥계 순환 모델의 동맥 탄성도 값을 조절함으로써 탄성도 변화에 대한 PWV를 계산 할 수 있었다. 이러한 수치적 방법을 사용하여 노화에 따른 동맥벽 탄성도의 저하가 심근세포의 Cross-bridge 동역학에 미치는 영향을 시뮬레이션 하였다.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.4
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• pp.239-252
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• 2007

Objectives: In the present study, we examined the differentiation potential of human adipose-(HAD) and human umbilical cord-derived mesenchymal like stem cells (HUC) into cardiomyocytes. Methods: Cells were initially exposed to 5-azacytidine for 24h cells and then were cultivated in the presence or absence of activin A, TGF-$\beta$1, or Wnt inhibitor with various combinations of BMP and FGF. Assessment of cardiomyogenic differentiation was made upon the expression of cardiomyocyte-specific genes using RT-PCR. Results: HAD that cultivated in control medium for 4 weeks after 5-azacytidine expose showed new expression of TnT gene and increased expression of Cmlc1 and kv4.3 genes. However, HAD cultivated in the presence of combinations of BMP-4/FGF-4 (B4/F4) and BMP-4/FGF-8 (B4/F8) showed new expression of $\beta$-MHC gene and more increased expression of Cmlc1, TnT, TnI, Kv4.3 genes. Significantly enhanced expression of Cmlc1, TnT, and Kv4.3 genes were also observed compared to that cultivated in the control medium. Treatment of HUC with either 5-azacytidine or combinations of BMP and FGF did not affect the expression profile of these genes. However, when activin A or TGF-$\beta$1 was present in addition to the BMP-2/FGF-8 (B2/F8) after 5-azacytidine exposure, HUC exhibited new expression of $\beta$-MHC gene and increased expression of $\alpha$-CA, TnT and Kv4.3 genes. When Wnt inhibitor was present in addition to BMP and FGF, HUC showed new expression of Cmlc1 gene and increased expression of $\alpha$-CA, TnT, TnI and Kv4.3 genes. Conclusions: Based on these observations, it is suggested that HAD and HUC could differentiate into cardiomyocytes which might be used as therapeutic cells for the heart diseases.

• Journal of Chest Surgery
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• v.37 no.7
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• pp.547-552
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• 2004

Recently, autologous bone marrow cell transplantation (CTx) for angiogenesis and myogenesis in ischemic myocardium has been extensively investigated to improve heart functions. This study was designed to evaluate the effects of CTx with off-pump coronary artery bypass grafting (OPCAB) in patients who were not feasible for complete revascularization. Material and Method: Four male patients underwent CTx and OPCAB simultaneously. Bone marrow was aspirated from iliac bone. Mean 1.5 ${\times}$ 10$^{9}$ mononuclear cells including mean 6.7 ${\times}$ 10$^{6}$ CD34 + cells and 3.7 ${\times}$ 10$^{6}$ AC133 + cells were obtained and concentrated with 10 cc. These cells were transplanted into non-graftable ischemic myocardium after OPCAB. The heart function of all patients were evaluated using the MIBI scan, echocardiogram and MRI preoperatively. The effects of CTx was evaluated using MIBI scan and echocardiogram at 1 month postoperatively. Result: An average of 2 grafts were bypassed to left anterior descending artery territory. Other territories were transplanted with isolated mononuclear cell. All patients had uncomplicated postoperative course. After 1 month follow up, there were improvement in symptom, ejection fraction (from 49% to 55%) on echocardiogram and myocardial perfusion on MIBI scan in all patients. Conclusion: These preliminary data showed improvement of heart function and myocardial perfusion and also showed the feasibility and safety of combined therapy with OPCAB and CTx in ischemic myocardium. However, the effectiveness of CTx alone cannot be readily assessed. Further randomized, controlled studies are required to evaluate the effectiveness of CTx alone.

• 순환기질환의공학회:학술대회논문집
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• 2005.12a
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• pp.55-56
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• 2005

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.70.1-70.1
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• 2005

• Biomedical Science Letters
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• v.6 no.4
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• pp.269-279
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• 2000

This present study was investigated to elucidate degenerative changes according to the change of habitual environment on the myocytes of doves by restricting them from flight that is instinct behavior of this animal and strong exercise. To restrict doves from flight, they were confined in the cage (1 $m^3$) for 2 months. After this period, the myocardium of the experimental group was compared to that of wild doves in the ultrastructural and cytochemical ways. In addition, stereological changes were also examined. The results were as followings: 1. The body weight of the confined experimental groups was higher than that of the wild doves, but the ratios of the pectoral muscle/body weight (p<0.05) and the heart/body weight were lower. 2. At the ultrastructural level, the myocardium of confined doves appeared as wavy fibers in the smaller area than in the myocardium of wild doves. Also, the length of sarcomeres was longer in the confined doves. The number of sarcoplasmic reticulum and capillary was smaller in the myocardium of confined doves. 3. Cytochemical examinations showed that the activities of cytochrome oxidase were lowered in the confined doves. 4. Stereological analysis revealed that the density of myofibrils was greater in the confined doves. In contrast the volume density of sarcoplasmic reticulum (p<0.05) and the surface density of mitochondrial inner membrane (p<0.05) was lower in the confined doves, while the numerical density of mitochondrial inner membrane was higher (p<0.05). These results suggest that even the short period of restricted exercise can induce negative effects on the functions of myocytes of doves that are adapted for the strong exercise such as flight. Therefore, the maintenance of prolonged exercise seems to be one of the important factors that are critical to retain the functions of myocardium.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.21-29
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• 2004

Purpose: Much evidence suggests long-term cigarette smoking alters coronary vascular endothelial response. On this study, we applied nonnegative matrix factorization (NMF), an unsupervised learning algorithm, to CO-less $H_2^{15}O-PET$ to investigate coronary endothelial dysfunction caused by smoking noninvasively. Materials and methods: This study enrolled eighteen young male volunteers consisting of 9 smokers $(23.8{\pm}1.1\;yr;\;6.5{\pm}2.5$ pack-years) and 9 nonsmokers $(23.8{\pm}2.9 yr)$. They do not have any cardiovascular risk factor or disease history. Myocardial $H_2^{15}O-PET$ was performed at rest, during cold ($5^{\circ}C$) pressor stimulation and during adenosine infusion. Left ventricular blood pool and myocardium were segmented on dynamic PET data by NMF method. Myocardial blood flow (MBF) was calculated from input and tissue functions by a single compartmental model with correction of partial volume and spillover effects. Results: There were no significant difference in resting MBF between the two groups (Smokers: 1.43 0.41 ml/g/min and non-smokers: $1.37{\pm}0.41$ ml/g/min p=NS). during cold pressor stimulation, MBF in smokers was significantly lower than 4hat in non-smokers ($1.25{\pm}0.34$ ml/g/min vs $1.59{\pm}0.29$ ml/gmin; p=0.019). The difference in the ratio of cold pressor MBF to resting MBF between the two groups was also significant (p=0.024; $90{\pm}24%$ in smokers and $122{\pm}28%$ in non-smokers.). During adenosine infusion, however, hyperemic MBF did not differ significantly between smokers and non-smokers ($5.81{\pm}1.99$ ml/g/min vs $5.11{\pm}1.31$ ml/g/min ; p=NS). Conclusion: in smokers, MBF during cold pressor stimulation was significantly lower compared wi4h nonsmokers, reflecting smoking-Induced endothelial dysfunction. However, there was no significant difference in MBF during adenosine-induced hyperemia between the two groups.

• The Korean Journal of Pharmacology
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• v.30 no.3
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• pp.321-330
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• 1994

The protective effect of 'ischemic preconditioning (PC)' on ischemia-reperfusion injury of heart has been reported in various animal species, but without known mechanisms in detail. In an attempt to investigate the cardioprotective mechanism of PC, we examined the effects of PC on the myocardial oxidative injuries and the oxygen free radical production in the ischemia-reperfusion model of isolated Langendorff preparations of rat hearts. PC was performed with three episodes of 5 min ischemia and 5 min reperfusion before the induction of prolonged ischemia (30 min)-reperfusion(20 min). PC prevented the depression of cardiac function (left ventricular pressure x heart rate) observed in the ischemic-reperfused heart, and reduced the release of lactate dehydrogenase during the reperfusion period. On electron microscopic pictures, myocardial ultrastructures were relatively well preserved in PC hearts as compared with non-PC ischemic-reperfused hearts. In PC hearts, lipid peroxidation of myocardial tissue as estimated from malondialdehyde production was markedly reduced. PC did not affect the activity of xanthine oxidase which is a major source of oxygen radicals in the ischemic rat hearts, but the myocardial content of hypoxanthine (a substrate for xanthine oxidase) was much lower in PC hearts. It is suggested from these results that PC brings about significant myocardial protection in ischemic-reperfused heart and this effect may be related to the suppression of oxygen free radical reactions.

• Korean Journal of Ichthyology
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• v.27 no.1
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• pp.26-32
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• 2015

The histological structure of the heart in Pseudorasbora parva was investigated by light microscope. The heart consisted of four consecutive chambers, the sinus venosus, atrium, ventricle and bulbus arteriosus. The wall of the sinus venosus was divided into endocardium, myocardium and epicardium, and the walls of the atrium and ventricle were divided into endocardium, subendocardium, myocardium, subepicardium and epicardium, and the wall of the bulbus arteriosus was divided into endocardium, subendocardium (ridge tissue), middle layer, subepicardium and epicardium. The valves were observed in the sinoatrial, artrioventricular and bulboventricular junctions. The sinus venosus wall was mostly made up of collagen. The rings of tissue were observed at the sinoatrial junction. The atrium was composed of a spongy trabeculate myocardium surrounded by an external rim of thin myocardium, and collagens were distributed in the subepicardium and trabeculae. The ventricle was a spongy myocardium with vessels in subepicardium. In the subepicardium and trabeculae of the ventricle, collagens were distributed. In the bulbus arteriosus, the diameter and length of the ridges were differed. The endocardial cells were convex and the non-clustered subendocardial cells showed irregular shapes. The cells of the middle layer were arranged into incomplete layers that showed different orientations. The subepicardium was formed by cells of different morphology. Collagens and elastins were demonstrated in the subendocardium, middle layer and subepicardium of the bulbus arteriosus. The epicardium was a single layer composed of flattened cells.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1992.05a
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• pp.36-36
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• 1992

기니픽심장에서 유두근을 적출하여 valve 쪽은 silver wire에 연결하여 수축력을 측정하고 mural end는 sylgard floor에 pin으로 고정하여 1Hz로 자극하였다. 이때 사용된 영양액은 Tyrode Ringer로 bath내 은도는 36$^{\circ}C$이고 97% 0$_2$, 3% $CO_2$로 포화시켜 사용하였다. 수축력이 일정해진 후 막전위는 conventional electrode를 이용해서 기록하고, 세포내 $Na^{＋}$ 이온 활성도( $a_{Na}$ $^{i}$ )는 $Na^{＋}$ 선택적 전극을 이용해서 기록하였다. 적출 기니픽 심근에서 pinacidil, cromakalim, RP49356 둥의 $K^{＋}$ channel opener는 활동전위 기간(APD)과 수축력 감소을 일으켰고, pinacidil과 cromakalim에 의한 APD 감소는 glibenclamide (10 $\mu$M)에 의해 거의 억제되었다. Pinacidil, RP49356 및 cromakalim에 의한 수축력 감소시 세포내 $Na^{＋}$ 이온농도( $a_{Na}$ $^{i}$ )의 감소가 나타났으며 glibenclamide(10 $\mu$M)에 의한 APD의 감소는 거의 차단되었으나 $a_{Na}$ $^{i}$ 감소는 일부 나타났으며 이때 수축력의 감소도 나타났다.