• Journal of Chest Surgery
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• v.32 no.7
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• pp.603-612
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• 1999

Background : It has been documented that brief repetitive periods of ischemia and reperfusion (ischemic preconditioning, IP) enhances the recovery of post-ischemic contractile function and reduces infarct size after a longer period of ischemia. Many mechanisms have been proposed to explain this process. Recent studies have suggested that transient increase in the intracellular calcium may have triggered the activation of protein kinase C(PKC); however, there are still many controversies. Accordingly, the author performed the present study to test the hypothesis that preconditioning with high concentration of calcium before sustained subsequent ischemia(calcium preconditioning) mimics IP by PKC activation. Material and Method : The isolated hearts from the New Zealand White rabbits(1.5∼2.0 kg body weight) Method: The isolated hearts from the New Zealand White rabbits(1.5∼2.0 kg body weight) were perfused with Tyrode solution by Langendorff technique. After stabilization of baseline hemodynamics, the hearts were subjected to 45-minute global ischemia followed by a 120-minute reperfusion with IP(IP group, n=13) or without IP(ischemic control, n=10). IP was induced by single episode of 5-minute global ischemia and 10-minute reperfusion. In the Ca2+ preconditioned group, perfusate containing 10(n=10) or 20 mM(n=11) CaCl2 was perfused for 10 minutes after 5-minute ischemia followed by a 45-minute global ischemia and a 120-minute reperfusion. Baseline PKC was measured after 50-minute perfusion without any treatment(n=5). Left ventricular function including developed pressure(LVDP), dP/dt, heart rate, left ventricular end-diastolic pressure(LVEDP) and coronary flow(CF) was measured. Myo car ial cytosolic and membrane PKC activities were measured by 32P-${\gamma}$-ATP incorporation into PKC-specific pepetide. The infarct size was determined using the TTC (tetrazolium salt) staining and planimetry. Data were analyzed using one-way analysis of variance(ANOVA) variance(ANOVA) and Tukey's post-hoc test. Result: IP increased the functional recovery including LVDP, dP/dt and CF(p<0.05) and lowered the ascending range of LVEDP(p<0.05); it also reduced the infarct size from 38% to 20%(p<0.05). In both of the Ca2+ preconditioned group, functional recovery was not significantly different in comparison with the ischemic control, however, the infarct size was reduced to 19∼23%(p<0.05). In comparison with the baseline(7.31 0.31 nmol/g tissue), the activities of the cytosolic PKC tended to decrease in both the IP and Ca2+ preconditioned groups, particularly in the 10 mM Ca2+ preconditioned group(4.19 0.39 nmol/g tissue, p<0.01); the activity of membrane PKC was significantly increased in both IP and 10 mM Ca2+ preconditioned group (p<0.05; 1.84 0.21, 4.00 0.14, and 4.02 0.70 nmol/g tissue in the baseline, IP, and 10 mM Ca2+ preconditioned group, respectively). However, the activity of both PKC fractions were not significantly different between the baseline and the ischemic control. Conclusion: These results indicate that in isolated Langendorff-perfused rabbit heart model, calcium preconditioning with high concentration of calcium does not improve post-ischemic functional recovery. However, it does have an effect of limiting(reducing) the infart size by ischemic preconditioning, and this cardioprotective effect, at least in part, may have resulted from the activation of PKC by calcium which acts as a messenger(or trigger) to activate membrane PKC.

• Journal of Life Science
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• v.20 no.4
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• pp.555-560
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• 2010

The objective of this study was to investigate levels of serum creatinine, CuSOD and MnSOD protein expression in the kidney after renal ischemic reperfusion with pre-exercise using heat shock protein 70.1 in knock-out mice (KO). The C57/BL6 strain (Wild type: WT) and KO were divided into 4 groups as follows: Sham control group (Sham), pre-exercise group (Ex), pre-exercise +ischemia group (Ex+IR), and ischemia group (IR). CuSOD and MnSOD expression were significantly decreased (p<0.01, p<0.05) and blood creatinine concentration was significantly increased (p<0.01) in the IR group of KO. In contrast, CuSOD and MnSOD expression in the Ex+IR group of KO were higher than the IR group, while creatinine concentration was significantly lower. These results suggest that Hsp70 is directly correlated to renal ischemic reperfusion injury. Pre-exercise in renal ischemia might prevent or inhibit positive oxidative stress inhibitory effects by increasing anti-oxidative enzymes (CuSOD, MnSOD) within the kidney and improve to prevent renal function. Thus, pre-exercise may have a protective role against renal injury after renal ischemia.

• Journal of Chest Surgery
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• v.36 no.3
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• pp.123-130
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• 2003

Background: In order to develop the acute heart failure model for the animal experiment of the pneumatic ventricular assist device, we decided to use young pig whose coronary artery distribution is almost the same as humans and also very cheap in price. The purpose of this study is to develop stable, reproducible acute ischemic heart failure model in swine using coronary artery ligation method. Material and Method: Five young pigs whose weights are the same as adult humans are under experiment. Each pig was under endotracheal intubation and connected to a mechanical ventilator. Through left lateral thoracotomy, we exposed the heart and induced ischemic heart failure by coronary artery ligation. The ligation began at the distal part of the left anterior descending coronary artery. After 5 minutes of initial ligation we reperfused the artery and then re-ligated. Before and after each ligation-reperfusion procedure we assessed the left ventricular end-diastolic pressure, arterial pressure, and cardiac index. We also measured left ventricular end-diastolic dimension, end-systolic dimension, fractional shortening, ejection fraction using intraoperative epicardial echocardiography. After appropriate heart failure was established with sequential (from distal part of LAD to proximal location) ligation-reperfusion-ligation procedure, we inserted the ventricular assist device and operated. Result: We established stable acute ischemic heart failure in 3 of 5 young pigs with this sequential ligation-reperfusion-ligation procedure, and could maintained 50% less ejection fraction before the procedure according to intraoperative epicardial echocardiography. We also observed no ventricular arrhythmia usually associated with simple coronary artery ligation in large animals and no cardiac arrest associated with ventricular arrhythmia or myocardial stunning. In pathologic specimen, we observed scattered ischemic myocardium in all around the ischemic field induced by coronary artery ligation. Conclusion: Under the concept of ischemic preconditioning, we developed safe and reproducible acute ischemic heart failure model in swine using sequential coronary artery ligation-reperfusion-ligation method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2223-2230
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• 2011

ECG is used to diagnose heart diseases such as myocardial ischemia, arrhythmia and myocardial infarction. Particularly, myocardial ischemia causes the shape change of the ST segment, this change is transient and may occur without symptoms. So it is important to detect the transient change of ST segment through long term monitoring. ST segment classification algorithm for making diagnosis myocardial ischemia is presented in this paper. The first step in the ST segment shape classification process is to detect R wave point and feature points based adaptive threshold and window. And then, the suggested algorithm detects the ST level change, To classify the ST segment shape, the suggested algorithm uses the slope values of the four points between the S and T wave. The ECG data in the European ST-T database were used to verify the performance of the developed algorithm. The best correct rate was 99.40% and the worst correct rate was 68.48%.

• Journal of Veterinary Clinics
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• v.27 no.5
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• pp.553-558
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• 2010

The purpose of this study was to investigate the effects of premedicated ascorbic acid and hepa-saline irrigation/aspiration on attenuation of ischemia-reperfusion (I/R) injury and recovery of renal function in canine nephrotomy model. In the canine model, nine mixed dogs were subjected to renal nephrotomy with premedicated ascorbic acid and hepa-saline irrigation-aspiration (treatment group 2), and only hepa-saline irrigation-aspiration (treatment group 1). The level of renal function and antioxidant enzymes after nephrotomy were measured. And the expression pattern of TNF-${\alpha}$ and INF-${\gamma}$ was examined in the renal tissue at $7^{th}$ day after nephrotomy. BUN and creatinine levels significantly decreased in the treatment group 1 and 2 compared to that of control group at the $3^{rd}$, 5th and $7^{th}$ day after reperfusion (p < 0.05). And, there was significant difference between treatment group 1 and 2 at the $3^{rd}$ day after reperfusion (p < 0.05). The activities of antioxidant enzymes in plasma was significantly increased in the treatment group 1 and 2 compared to that of control group at the $3^{rd}$, $5^{th}$ and $7^{th}$ day after reperfusion (p < 0.05). And, there was significant difference between treatment group 1 and 2 at the $3^{rd}$ day after reperfusion (p < 0.05). TNF-${\alpha}$ was decreased and INF-${\gamma}$ was increased in treatment groups. The result of this study suggested that irrigation-aspiration has effects on attenuation of renal ischemia-reperfusion injury, and the exogenous ascorbic acid has a role in the attenuation of renal ischemia-reperfusion injury and recovery of renal function in canine nephrotomy model.

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.94-98
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• 2007

This study was to investigate the effects of ascorbic acid and alpha-tocopherol on the attenuation of renal ischemia-reperfusion (IR) injury in pigs. Ten pigs were subjected to 60 minutes of warm unilateral renal ischemia followed by removal of contralateral kidney and then divided into two groups. Treatment group was performed ascorbic acid and alpha-tocopherol pretreatment 2 days before operation and ascorbic acid with heparin-saline solution irrigation-aspiration. Otherwise, control group used only irrigation-aspiration of heparin-saline solution. Blood samples were collected from these pigs for measurement of serum blood urea nitrogen (BUN) and creatinine values, antioxidant superoxide dismutase (SOD) at pre, day 1, day 3, day 7 and day 14. The kidneys were taken for histopathologic evaluation after euthanasia on postoperative day 14. The levels of BUN were significantly increased in the control group on day 1, day 3 and day 7 (P<0.05). And the level of creatinine was significantly increased in the control group on day 3 (p<0.05). Activity of antioxidant enzymes in plasma revealed significant difference (p<0.05) between control and treatment group at day 14. In histopathologic findings, treatment group was showed less damage than that of control group on the basis of renal tubular damage. It was concluded that ascorbic acid and alpha-tocopherol attenuated renal I/R injury in the pigs.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.29-35
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• 2009

This study was to determine the effects of ascorbic acid and alpha-tocopherol on the attenuation of an ischemia-reperfusion injury (IRI) after renal auto-transplantation in a pig model. In the treatment group, three pigs were subjected to a renal auto-transplantation followed by the administration of ascorbic acid and alpha-tocopherol and the flushing of ascorbic acid plus hepa-saline solution. Otherwise, the control group used only flushing of hepa-saline solution. Blood samples were collected from these pigs for measurement of serum blood urea nitrogen (BUN) and creatinine values on the day before surgery and day 1, 3, 5 and 7 after surgery. The kidneys were taken for histopathological evaluation following euthanasia on day 14 after surgery. Serum creatinine and BUN values showed a significantly difference between control and treatment group on day 1, 3 and 5 (P<0.05). In histopathologic findings, treatment group showed less damage than that of the control group on the basis of renal tubular damage. As a result, this study suggests that the exogenous ascorbic acid and alpha-tocopherol pretreatment therapy with ascorbic acid irrigation-aspiration has a role of attenuation of renal I/R injury and recovery of renal function in a pig transplantation model.

• Journal of Life Science
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• v.19 no.6
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• pp.818-824
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• 2009

The mechanisms responsible for ischemia/reperfusion (I/R) injury have direct or indirect relevance to clinical lung injury after severe shock, cardiopulmonary bypass, and transplantation. This study investigated the effects of aspirin on intestinal I/R-induced acute lung injury (ALI) in rats. Lipopolysaccharide (LPS) induced cyclooxygenase-2 (COX-2) expression in A549 and RAW264.7 cells. RAW264.7 macrophages had shown greater expression of COX-2 than A549 cells. In addition, the NADPH oxidase inhibitor apocynin and p38 MAPK inhibitor SB203580 attenuated LPS-stimulated COX-2 expression. To induce ALI, intestinal ischemia was performed for 60 min prior to the 4 hr reperfusion by clamping the superior mesenteric artery in Sprague-Dawley rats. In order to test and compare the effect of non-specific COX inhibitor aspirin with the effect of mepacrine, a well known phospholipase$A_{2}$ inhibitor, rats were divided into 4 groups: Sham, I/R, Mepa+I/R (mepacrine, 60 mg/kg, i.p.), ASA+I/R (aspirin, 10 mg/kg, i.p.). In the present investigation, myeloperoxidase activities in the lung and intestinal tissues were increased by I/R. These changes were reduced by single pretreatment of mepacrine (60 mg/kg, i.p.) or aspirin (10 mg/kg, i.p.) 30 min before I/R. Structural studies demonstrated that the tissue injuries in the lung and intestine after I/R were also attenuated by the pretreatment of mepacrine or aspirin. These results suggest that I/R-induced ALI is mediated, in part, by the activation of COX. In addition, pretreatment of aspirin might be helpful for the prevention of ALI in ARDS-prone patients. In addition, the p38 MAPK inhibitor and apocynin also might be helpful to ALI through the inhibition of COX-2 expression.

• Journal of Chest Surgery
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• v.40 no.3 s.272
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• pp.168-179
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• 2007

Background: The recent trend of an increasing number of patients with acute cardiogenic shock or chronic congestive heart failure following myocardial infarction, as well as the considerable number who can not be weaned from cardiopulmonary bypass after open heart surgery, call for immediate efforts to develop affordable ventricular assist devices that are suitable for the Korean physique. Recently, a pneumatic pulsatile ventricular assist device (VAD), named DKUH-75, has been developed by the Department of Biomedical Engineering, in collaboration with the Department of Thoracic and Cardiovascular Surgery of Dankook University College of Medicine. The feasibility of the DKUH-75 VAD was evaluated on the bases of common hemodynamic variables and echocardiographic measurements in pigs, which are subjected to an acute cardiogenic shock state following myocardial infarction, using a novel coronary artery ligation method employing the ischemic preconditioning concept. Material and Method: Acute cardiogenic shock was induced in 10 Yorkshire Landrace Duroc strain pigs by ligating the left anterior descending coronary artery via an ischemic preconditioning process. The hemodynamic variables were monitored, with epicardial echocardiographic measurements performed before and one hour after the ligation. The DKUH-75 VAD was implanted into 5 pigs one hour after the onset of the shock. The hemodynamic variables and echocardiographic measurements were taken one hour after installation of the VAD. Result: The systolic, diastolic and mean systemic arterial pressures were significantly decreased in all the experimental animals one hour after the ligation. The systolic, diastolic and mean pulmonary arterial pressures were increased (Eds note: this completely contradicts the preceding statement? However, if you mean the non-experimental animals this should be stated?). The left ventricular end diastolic pressure (LVEDP) was increased, but the cardiac index decreased, An increase in the left ventricular end systolic dimension and decreases in the fractional shortening and ejection fraction were observed all animals one hour after the coronary artery ligation. In all 5 of the VAD implanted pigs, the systolic and mean systemic arterial pressures were increased, and the pulmonary arterial pressures decreased one hour after the implantation; the LVEDP decreased, but the cardiac index was significantly increased, In the echocardiographic measurements, the left ventricular end systolic dimension decreased after the implantation of the VAD, but the fractional shortening and ejection fraction significantly increased. Conclusion: Significant improvements in the hemodynamic variables and echocardiographic measurements were observed in the 5 VAD implanted animals one hour after installation, which had been subjected to an acute cardiogenic shock state by ligation of the coronary artery, indicating that the DKUH-75 VAD could help in the recovery of the myocardial function. This suggests that the DKUH-75 VAD is feasible in the short term in relation to an acute cardiogenic shock state due to myocardial infarction.

• Composites Research
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• v.12 no.4
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• pp.71-78
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• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with diaminodiphenyl methane (DDM), diaminodiphenyl sulphone (DDS) in a stoichiometrically equivalent ratio. From this work, the effect of aromatic amine curing agents. In contrast, the results show that the DGEBA/DDS cure system having the sulfone structure between the benzene rings had higher values in the conversion of epoxide, density, shrinkage (%), glass transition temperature, tensile modulus and strength, flexural modulus and strength than the DGEBA/DDM cure system having methylene structure between the benzene rings, whereas the DGEBA/DDM cure system presented higher values in the maximum exothermic temperature, thermal expansion coefficient, and thermal stability. These results are caused by the relative effects of sulfone group having strong electronegativity and methylene group having (+) repulsive property and stem from the effect of the conversion ratio of epoxide group. The result of fractography shows that the each grain size of the DDM/DGEBA system with feather-like structure is larger than that of the DDS/DGEBA system.