• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.225-234
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• 1992

In order to use a low cost polymer valve in our total artificial heart and ventricular assist device, we have developed a slit-type bileaflet polymer valve[BPV 1. The aim of this study is to determine the hydrodynamic effectiveness of the newly-designed BPV and its feasibility for temporary use in the blood pumps. For hydrodynamic comparison, we investigated in-vitro the pressure drop across the valve, the leakage volume, the flow rate and the flow pattern of the BPV, two mechanical valves and a trileaflet polymer valve. We employed the ventriculo-pulmonary bypassing method for in-vivo tests of the BPV's together vilh our electrohydraulic left venIn ricular assist device in mongrel dogs. The BPV showed adquate gydrodynamic performances and in the preliminary animal bests, there was no xvi dence of thrombus formation on the valve leaflets and around the struts. Detailed results obtained from the animal tests will be separately reported. This report involves the design criteria, fabrication and hydrodynamic charateristics of she BPV, and the basic merits and demerits of the valve are dis- cussed from the hydrodynamic point of view.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.77-88
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• 1992

Recently, diabetic patients are increasing in the field of microvascular surgery. Diabetes melltius is known to be related to arterial damage, platelet malfunction and thrombus formation. After microvascular anastomosis, delayed repair and vascular occlusion occurred more frequently in diabetic state. This study was performed to investigate the patency rate and process of endothelial healing after microvascular anastomosis of femoral artery in diabetic rat by scanning electron microscope. The animals were divided into two groups, 20 diabetic-induced and 20 non-diabetic groups. Diabetes was induced with a injection of Streptozotocin(50mg/kg b.w., Sigma Chemical Co.) to tail vein. The results obtained were as follows: 1. Macroscopically, anastomotic site was intact except a few cases showed minimal inflammatory sign around the wound site. But the inflammatory change was frequently occurred in diabetic-induced group. 2. The patency rate was 95% (19/20) in non-diabetic group and 65% (13/20) in diabetic-induced group. 3. In the non-diabetic group, anstomotic region was mostly endothelized by the alignment along the long axis of vessel but stitchs were not covered with endothelial cells. The thichkening of vessel wall was not observed. 4. In the diabetic-induced group, anastomotic region was not endothelized but covered with blood cellular components and connective tissue instead of endothelial cells. The thickening of the vessel wall was prominent in some diabetic-induced rats. These results suggest that diabetes was related to delayed regeneration of endothelium of vessels after microsurgical anastomosis.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.947-954
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• 1992

Polyethylene glycol (PEG) grafted poly (γ-benzyl L-glutamate) (PBLG) was synthesized by the substitution reaction of PBLG and PEG having primary amino groups at both ends. PEG-g-PBLG films containing hydroxyl group were also prepared by the substitution reaction of PEG-g-PBLG film and ethanolamine (EA). Adhesion of platelets and activation of plasma proteins on the copolypeptide films were studied. The results showed that platelets are less adhered and activated on the PEG-g-PBLG than on other polypeptides and plasma recalcification time (PRT) on the PEG-g-PBLG was longer than that on other polypeptides. These results were consistent with those of blood clotting time and thrombus formation on the polypeptides. As a results, PEG-g-PBLG surfaces showed better blood compatibility than PBLG or PEG-g-PBLG-EA surfaces.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.375-383
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• 2002

Aneurysm embolisation method using coils have been widely used. Micro coils are introduced via a small catheter, and are packed inside of aneurysm sac, which induces intraaneurysmal flow stagnation and thrombus formation. When partial blocking of an aneurysm is inevitable, the location of coils is important since it changes the flow patterns inside the aneurysm, which affect the embolisation process. We measured the flow field inside the partially blocked lateral aneurysm models in vitro, and tried to suggest the effective locations of coils for aneurysm embolisation. Velocity fields are measured using a particle image velocitimeter for different coil locations- proximal neck, distal neck, proximal dome and distal dome. Flow into the aneurysm sac was significantly reduced in the distally blocked models, and coils at distal neck blocked inflow more effectively comparing to those at distal dome. This study suggests that distal neck should be the most effective location for aneurysm embolisation.

• Journal of Korean Neurosurgical Society
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• v.64 no.6
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• pp.853-863
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• 2021

Objective : Biodegradable poly-L-lactic acid (PLLA) with a highly biocompatible surface via tantalum (Ta) ion implantation can be an innovative solution for the problems associated with current biodegradable stents. The purpose of this study is to develop a Taimplanted PLLA stent for clinical use and to investigate its biological performance capabilities. Methods : A series of in vitro and in vivo tests were used to assess the biological performance of bare and Ta-implanted PLLA stents. The re-endothelialization ability and thrombogenicity were examined through in vitro endothelial cell and platelet adhesion tests. An in vivo swine model was used to evaluate the effects of Ta ion implantation on subacute restenosis and thrombosis. Angiographic and histologic evaluations were conducted at one, two and three months post-treatment. Results : The Ta-implanted PLLA stent was successfully fabricated, exhibiting a smooth surface morphology and modified layer integration. After Ta ion implantation, the surface properties were more favorable for rapid endothelialization and for less platelet attachment compared to the bare PLLA stent. In an in vivo animal test, follow-up angiography showed no evidence of in-stent stenosis in either group. In a microscopic histologic examination, luminal thrombus formation was significantly suppressed in the Ta-implanted PLLA stent group according to the 2-month follow-up assessment (21.2% vs. 63.9%, p=0.005). Cells positive for CD 68, a marker for the monocyte lineage, were less frequently identified around the Ta-implanted PLLA stent in the 1-month follow-up assessments. Conclusion : The use of a Ta-implanted PLLA stent appears to promote re-endothelialization and anti-thrombogenicity.

• Journal of Ginseng Research
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• v.43 no.2
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• pp.236-241
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• 2019

Background: Thromboxane A2 ($TXA_2$) induces platelet aggregation and promotes thrombus formation. Although ginsenoside Ro (G-Ro) from Panax ginseng is known to exhibit a $Ca^{2+}-antagonistic$ antiplatelet effect, whether it inhibits $Ca^{2+}-dependent$ cytosolic phospholipase $A_2$ ($cPLA_{2{\alpha}}$) activity to prevent the release of arachidonic acid (AA), a $TXA_2$ precursor, is unknown. In this study, we attempted to identify the mechanism underlying G-Ro-mediated $TXA_2$ inhibition. Methods: We investigated whether G-Ro attenuates $TXA_2$ production and its associated molecules, such as cyclooxygenase-1 (COX-1), $TXA_2$ synthase (TXAS), $cPLA_{2{\alpha}}$, mitogen-activated protein kinases, and AA. To assay COX-1 and TXAS, we used microsomal fraction of platelets. Results: G-Ro reduced $TXA_2$ production by inhibiting AA release. It acted by decreasing the phosphorylation of $cPLA_{2{\alpha}}$, p38-mitogen-activated protein kinase, and c-Jun N-terminal kinase1, rather than by inhibiting COX-1 and TXAS in thrombin-activated human platelets. Conclusion: G-Ro inhibits AA release to attenuate $TXA_2$ production, which may counteract $TXA_2-associated$ thrombosis.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.93-100
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• 2019

The root of Panax ginseng is used in ethnomedicine throughout eastern Asia and various recent studies have proved that Panax ginseng has inhibitory effects on cardiovascular disease. Each factor causing cardiovascular disease is known to have a very complex process which is achieved by a diverse number of mechanisms. Among these factors, platelets are the most important because they directly participate in thrombogenesis. Therefore, inhibiting the activity of platelets is an essential element for prevention of cardiovascular diseases. Our previous study showed the antiplatelet effects of Korean red ginseng extract and two of its components, ginsenoside Rg3 and ginsenoside Ro. However, the inhibitory mechanism of other ginsenosides remains unclear. Therefore, we investigated the inhibitory mechanism of ginsenoside F4 (G-F4) from Korean red ginseng on the regulation of signaling molecules involved in human platelet aggregation. With the use of G-F4, collagen-induced human platelet aggregation was inhibited in a dose-dependent manner, and it suppressed collagen-induced elevation of $[Ca^{2+}]_i$ mobilization through elevated phosphorylation of inositol 1, 4, 5-triphosphate receptor I ($Ser^{1756}$). In addition, G-F4 inhibited fibrinogen binding to ${\alpha}IIb/{\beta}_3$ during collagen-induced human platelet aggregation. Thus, in the present study, G-F4 showed an inhibitory effect on human platelet activation, suggesting its potential use as a new natural medicine for preventing platelet-mediated cardiovascular diseases.

• Journal of Ginseng Research
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• v.45 no.4
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• pp.490-497
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• 2021

Background and objective: Synthetic ginsenoside compounds G-Rp (1,3, and 4) and natural ginsenosides in Panax ginseng 20(S)-Rg3, Rg6, F4 and Ro have inhibitory actions on human platelets. However, the inhibitory mechanism of ginsenoside Rk1 (G-Rk1) is still unclear thus, we initiated investigation of the anti-platelet mechanism by G-Rk1 from Panax ginseng. Methodology: Our study focused to investigate the action of G-Rk1 on agonist-stimulated human platelet aggregation, inhibition of platelet signaling molecules such as fibrinogen binding with integrin α_IIbβ₃ using flow cytometry, intracellular calcium mobilization, fibronectin adhesion, dense granule secretion, and thromboxane B2 secretion. Thrombin-induced clot retraction was also observed in human platelets. Key Results: Collagen, thrombin, and U46619-stimulated human platelet aggregation were dose-dependently inhibited by G-Rk1, while it demonstrated a more effective suppression on collagen-stimulated platelet aggregation using human platelets. Moreover, G-Rk1 suppressed collagen-induced elevation of Ca²⁺ release from endoplasmic reticulum, granule release, and α_IIbβ₃ activity without any cytotoxicity. Conclusions and implications: These results indicate that G-Rk1 possess strong anti-platelet effect, proposing a new drug candidate for treatment and prevention of platelet-mediated thrombosis in cardiovascular disease.

• Journal of the Korean Orthopaedic Association
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• v.56 no.5
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• pp.450-454
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• 2021

A 75-year-old male patient without any significant medical and habitual risk factors for acute atherosclerosis obliterans except for hypertension was diagnosed with coronavirus disease 2019 with dyspnea, coughing, and mild fever. After a week of hospitalization, he complained of right foot pain and numbness. The symptoms were aggravated during the next week, resulting in a complete toe color change and loss of dorsalis artery pulse. Enhanced 3-dimensional computed tomography angiography revealed thrombus formation in the right common iliac artery and a loss of blood flow below the popliteal artery on both sides. The patient underwent percutaneous balloon angioplasty with stent insertion followed by medical therapy for anticoagulation. The clinical symptoms immediately were improved after the intervention, but the great toe necrosis was not recovered. Finally, amputation of the great toe was performed.

• Archives of Pharmacal Research
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• v.26 no.3
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• pp.224-231
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• 2003

The anti-thrombotic effects of LB30057, a direct thrombin inhibitor, were evaluated with in vivo rat and dog thrombosis models. In rats, 1 mg/kg of LB30057 inhibited half of the clot formations in the inferior vena cava at 5 minutes after intravenous application. When measured at 2 hours after oral application, 100 mg/kg prevented approximately half of the clot formations in the inferior vena cava and 50 mg/kg prolonged the mean occlusion time from $15.6{\pm}1.3$ minutes to $47.2{\pm}8.3$ minutes in the carotid artery. In dogs, the formation of thrombus in the jugular vein was reduced to half at a dose range of 20-30 mg/kg at 6 hours after oral application. In addition, the LB30057 dosage required to reduce venous clot formation by approximately 80-90% in dogs was only about 10% of that required for the same reduction in rats. This is probably due to the variation in its time-dependent blood concentration profiles in each species; for example, the plasma half-life of LB71350 in dogs was longer than that in rats ($153.0{\pm}3.0$ vs. $129.7{\pm}12.7$ min at 30 mg/kg, i.v., respectively). AUG, $T_{max},{\;}G_{max}$, and BA in dogs were 59, 8.9, 9.17, and 13.3 times higher than those in rats at oral 30 mg/kg, respectively. Taken together, these results suggest that LB30057 administered orally is effective in the prevention of arterial and venous thrombosis in rats and dogs. It therefore represents a good lead compound for investigations to discover a new, orally available, therapeutic agent for treating thrombotic diseases.