• Journal of Mechanical Science and Technology
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• v.17 no.7
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• pp.1104-1110
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• 2003

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the blood samples after treatment was higher than before treatment. These treated blood samples were forced to flow through a capillary tube that was vibrated perpendicularly to the direction of the flow. The experimental results showed that vibration caused a reduction of the flow resistance of the non-aggregated blood. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. These results show potential in treating various diseases in the microcirculation associated with blood cell aggregation.

• Korea-Australia Rheology Journal
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• v.19 no.2
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• pp.61-66
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• 2007

The aggregation characteristics of red blood cells (RBCs) are known as important factors in the microvascular flow system, and increased RBC aggregation has been observed in various pathological diseases, such as thrombosis and myocardial infarction. This paper describes a simple microfluidic device for measuring the RBC aggregation by integrating a microfluidic slit rheometry and laser-backscattering technique. While a decreasing-pressure mechanism was applied to the microfluidic rheometry, a syllectogram (the light intensity versus time) showed an initial increase and a peak caused by the high shear stress-induced disaggregation, immediately followed by a decrease in the light intensity due to RBC aggregation. The critical shear stress (CST) corresponding to the peak intensity was examined as a new index of the RBC aggregation characteristics. The CST of RBCs increased with increasing aggregation-dominating protein (fibrinogen) in the blood plasma. The essential feature of this design was the combination of the rheometric-optic characterization of RBC aggregation with a microfluidic chip, which may potentially allow cell aggregation measurements to be easily carried out in a clinical setting.

• Journal of Chest Surgery
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• v.49 no.3
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• pp.145-150
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• 2016

Background: Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. Methods: Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was performed before and at 1, 2, and 3 hours after ECC commencement. To eliminate bias induced by hematocrit and plasma, all blood samples were adjusted to a hematocrit of 45% using baseline plasma. Blood viscoelasticity, plasma viscosity, hematocrit, arterial blood gas analysis, central venous $O_2$ saturation, and lactate were measured. Results: The blood viscosity and aggregation index decreased abruptly 1 hour after ECC and then remained low during ECC in both groups, but blood elasticity did not change during ECC. Blood viscosity, blood elasticity, plasma viscosity, and the aggregation index were not significantly different in the groups at any time. Hematocrit decreased abruptly 1 hour after ECC in both groups due to dilution by the priming solution used. Conclusion: After ECC, blood viscoelasticity and RBC aggregation were not different in the pulsatile and nonpulsatile groups in the adult dog model. Furthermore, pulsatile flow did not have a more harmful effect on blood viscoelasticity or RBC aggregation than nonpulsatile flow.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.109-115
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• 2007

A new microchip-based aggregometer that uses a stirring-aided disaggregation mechanism in a microchip was developed to measure red blood cell (RBC) aggregation in blood and RBC suspensions. Conventional methods of RBC disaggregation, such as the rotational Couette system, were replaced with a newly designed stirring-induced disaggregation mechanism. Using a stirrer in a microchip, the aggregated RBCs stored in a microchip can be easily disaggregated. With an abrupt halt of the stirring, the backscattered light intensity can be measured in a microchip with respect to time. The time recording of the backscattered light intensity (syllectogram) shows an exponential decreasing curve representing the RBC aggregation. By analyzing the syllectogram, aggregation indices such as AI and M were determined. The results showed excellent agreement with LORCA. The essential feature of this design is the incorporation of a disposable microchip and the stirring-induced disaggregation mechanism.

• Journal of Ginseng Research
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• v.46 no.5
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• pp.683-689
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• 2022

Background: Since ginsenosides exert an anti-thrombotic activity, blood flow-improving effects of DK-MGAR101, an extract of mountain ginseng adventitious roots (MGAR) containing various ginsenosides, were investigated in comparison with an extract of Korean Red Ginseng (ERG). Methods: In Sprague-Dawley rats orally administered with DK-MGAR101 or ERG, oxidative carotid arterial thrombosis was induced with FeCl₃ (35%), and their blood flow and occlusion time were measured. To elucidate underlying mechanisms, the cytoprotective activities on rat aortic endothelial cells (RAOECs) exposed to hydrogen peroxide (H₂O₂) were confirmed. In addition, the inhibitory activities of DK-MGAR101 and ERG on agonist-induced platelet aggregation, thromboxane B₂ production, and ATP granule release from stimulated platelets as well as blood coagulation were analyzed. Results: DK-MGAR101 containing high concentrations of Rb1, Rg1, Rg3, Rg5, and Rk1 ginsenosides (55.07 mg/g) was more effective than ERG (ginsenosides 8.45 mg/g) in protecting RAOECs against H₂O₂ cytotoxicity. DK-MGAR101 was superior to ERG not only in suppressing platelet aggregation, thromboxane B₂ production, and granule release, but also in delaying blood coagulation, FeCl₃-induced arterial occlusion, and thrombus formation. Conclusions: The results indicate that DK-MGAR101 prevents blood vessel occlusion by suppressing platelet aggregation, thrombosis, and blood coagulation, in addition to endothelial cell injury.

• Korea-Australia Rheology Journal
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• v.20 no.4
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• pp.253-260
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• 2008

A method based on transient shear flow dynamics of red cell aggregates was developed to investigate reversible re-aggregation processes with decreasing shear flow. In the microchannel-flow aggregometry, the aggregated red blood cells that are subjected to continuously decreasing shear stress in microchannel flow were measured with the use of a laser-scattering technique. Both the laser-backscattered intensity and pressure were simultaneously measured with respect to time, resulting in shear stress ranging from $0{\sim}35\;Pa$ for a time period of less than 30 seconds. The time dependent recording of the backscattered light intensity (syllectogram) yielded an upward convex curve with a peak point, which reflected the transition threshold of aggregation in the RBC suspensions. Critical-time and critical-shear stress corresponding to the peak point were examined by varying the initial pressure-differential and the micro channel depth, and these results showed good potential for being used as new aggregation indices. In the present study, these newly proposed indices were also validated by differentiating the effect of fibrinogen on RBC aggregation and then these indices were compared to the conventional indices that were measured by a rotational aggregometer.

• 순환기질환의공학회:학술대회논문집
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• 2004.11a
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• pp.36-37
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• 2004

• The Journal of Internal Korean Medicine
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• v.21 no.5
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• pp.705-713
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• 2000

Objectives : The purpose of this study was to investigate the effect of Intravascular Laser Irradiation of Blood(ILlB) by the live blood analysis. Methods : We had analysed the changing forms of the live blood samples with Ultra Darkfield Microscope before and after Intravascular Laser Irradiation of Blood. Results : 1. Somatid did not showed significant change. 2. In the rouleau of red blood cells was decreased significantly. 3. In the morphological change of red blood cells, Burr cell, Ovalocyte and Poikilocyte were decreased significantly, but Acanthocyte and Target cell were increased significantly. 4. In the abnormal matters in plasma, the Cholesterol cristal did not showed significant change, but the Aggregation of platelet, Lipids, Spicule, Leucocyte, Uric acid cristal did showed a little significant decrease. Conclusion : These findings suggest that live blood analysis is useful to judge the effect of treatment and diagnosis in oriental medicine, and with the effect of Intravascular Laser Irradiation of Blood, it had showed significant effect on rouleau of red blood cells, morphological change of red blood cells and abnormal matters in plasma.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.41-49
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• 1989

The study was undertaken to obtain indirect values of volume of packed red cell (VPRC) without centrifugation, using the erythrocyte sedimentation rate (ESR) of diluted blood in dogs. ESRs of diluted blood using the diluent of autologous plasma in which formed numerous RBC-rouleau clumps, autologous serum in which formed a few RBC-rouleau clumps, and 5% dextrose or 6% sucrose solutions in which formed numerous RBC-aggregation clumps, were accelerated. But, ESR of diluted blood using the 0.9% saline, D-S, ACD-B, CDP or D-PBS solutions were sluggish, because erythrocytes were dispersed in these diluents. Reliable values of VPRC on the basis of the correlating regressive equation to the ESR could be derived from values of$60^{\circ}$-angled-micro-ESR/40 min in the mixture, four parts of 5% dextrose solution and one part of whole blood. In the ESR values of diluted blood with low ratio, 1:1~3:1, $60^{\circ}$-micro-ESR was higher than $60^{\circ}$-Wintrobe-ESR. But, in the diluted blood with high ratio, 4:1~5:1, there was no different ESR values. For an aid of practical use, authers suggested a list of the $60^{\circ}$-micro-ESR/40 min in the diluted blood with equivalent VPRC of whole blood.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.371-372
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• 2002

It is well known that red blood cells (RBCs) are suffered from chronic stresses in systemic circulation. The objective of this study is to clarify the effect of the aging of RBCs on rheological properties and hemolysis. Initially, RBCs age fractionation was performed by using a high-speed centrifugation (15[min] at 1500[G]), then young and aged RBCs were suspended in plasma to adjust the hematocrit level of 40[%]. After this pretreatment, the viscosity was measured by using a capillary type and a cone-plate type viscometers, respectively, and the hemolysis test was carried out by a seesaw type shaker. Results from these experiments showed that the viscosity of the aged RBCs measured by the capillary viscometer was increased by 10[%] as compared with that of the young RBCs. Under the condition of all shear zones, the viscosity of the aged RBCs was increased in case of using the cone-plate type viscometer. And the hemolytic level was increased twice as the aging. The data obtained in this study indicated that the ability of aggregation of RBCs was increased and the deformability of RBCs membrane got lower with the aging. Furthermore, it was exhibited that the fragility of RBCs ’ membrane was increased with the aging.