• Korea-Australia Rheology Journal
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• 제17권1호
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• pp.9-13
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• 2005

The aggregation of red blood cells (RBCs) is a major determinant of blood flow resistance passing through various veins. Available techniques for measuring RBC aggregation often require pretreating and washing after each measurement, which is not optimal for day-to-day clinical use. A laser reflection technique has been combined with a vibration-aided disaggregation mechanism, which shows significant advances in aggregometer design, operation and data analysis. The essential features of this design are in its simplicity and a disposable element that is in contact with the blood sample. Using extremely small quantities of blood, the RBCs subjected to vibrations can be quickly and completely disaggregated. This is followed by measuring the backscattered light intensity. The measurements with the present sensor were compared with those of a commercial aggregometer and a strong correlation was found between them. The newly-developed optical aggregometer can measure the RBC aggregability difference between young and old cell suspension with ease and accuracy.

• Korea-Australia Rheology Journal
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• 제19권3호
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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.

• 동의생리병리학회지
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• 제23권5호
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• pp.980-985
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• 2009

The study was designed to test anti-platelet effect and find out anti-platelet mechanism of extract from Gamisopunghwalheol-tang in vitro. The extract was investigated for the inhibition against the aggregation of human platelet suspensions induced from collagen by aggregometer. And also the extract was investigated for the inhibition against the aggregation of human platelet suspensions who is taking aspirin or clopidogrel induced from collagen by aggregometer. In collagen-induced platelet aggregation test, the extract significantly inhibited collagen-induced platelet aggregation in a concentration-dependent manner(p<0.05). The extract significantly inhibited collagen-induced platelet aggregation of human platelet who is taking aspirin or clopidogrel ing 0 mg/ml concentration(p<0.05). And the extract inhibited more ingpatients who is taking aspirin. These results show that the extract from Gamisopunghwalheol-tang has anti-platelet aggregation effect.

• 약학회지
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• 제56권6호
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• pp.382-389
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• 2012

Effects of citrate-capped silver nanoparticles (AgNPs) on the blood coagulation and platelet aggregation were investigated using whole blood, platelet rich plasma (PRP) and washed platelet obtained from SD male rats. To confirm the stability of AgNPs in the test, size distribution of the nanoparticles was measured in the vehicles including distilled water, serum, and platelet buffers. The average size of AgNPs was 20 nm in the vehicles, which means that the stability was maintained during the whole experimental period. When blood coagulation was monitored by using whole blood impedance aggregometer, coagulation was not observed at the concentration of 1, 10 and 50 ppm. Platelets in plasma or in buffer were not aggregated by AgNPs at the concentration of 1, 2 and 4 ppm, respectively. The test concentration of AgNPs could not be increased because the dark color of the nanoparticles impeded the transmission of light, which is an indicator of aggregation. Although the blood or platelets were pre-activated by collagen, thrombin, or ADP with sub-threshold level, aggregation was not observed at the test concentration. Microscopic observation also supported the result obtained by the aggregometer.

• Food Science and Biotechnology
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• 제15권5호
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• pp.763-767
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• 2006

The anticoagulant properties of compounds derived from fennel (Foeniculum vulgare Gaertner) fruits were evaluated using a platelet aggregometer and compared with aspirin. The active constituents of fennel fruits were isolated and identified as (+)-fenchone and extragole by various spectral analysis techniques. With regard to the 50% inhibitory concentration ($IC_{50}$), (+)-fenchone effectively inhibited platelet aggregation induced by treatment with collagen ($IC_{50}$, $3.9\;{\mu}M$) and arachidonic acid (AA) ($IC_{50}$, $27.1\;{\mu}M$), and estragole inhibited collagen-induced platelet aggregation ($IC_{50}$, $4.7\;{\mu}M$). By way of comparison, (+)-fenchone and estragole proved to be significantly more potent than aspirin at inhibiting platelet aggregation induced by collagen. The inhibitory activity of (+)-fenchone toward platelet aggregation induced by AA was 1.3 times stronger than that of aspirin. These results indicate that (+)- fenchone and estragole may be useful as lead compounds for inhibiting platelet aggregation induced by arachidonic acid and collagen.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1510-1515
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• 2004

Aggregability of red blood cells (RBCs) was determined by a laser backscattering light analysis in a microfluidic channel. Available techniques for RBC aggregation often adopt a rotational Couette-flow using bob-and-cup system for disaggregating RBCs, which causes the system to be complex and expensive. A disposable microfluidic channel and vibration generating mechanism were used in the proposed new detection system for RBC aggregation. Prior to measurement, RBC aggregates in a blood sample were completely disaggregated by applying vibration-induced shear. With the present apparatus, the aggregation indexes of RBCs can be easily measured with small quantities of blood sample. The measurements with the present aggregometer were compared with those of LORCA and showed a strong correlation between them. The aggregability of the defibrinogenated blood RBCs is markedly lower than that of the normal RBCs. The noble feature of this design is the vibration-induced disaggregation mechanism, which enables to incorporate disposable element that holds the blood sample.

• Environmental Analysis Health and Toxicology
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• 제23권4호
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• pp.285-290
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• 2008

Effects of titanium dioxide nanoparticles on blood coagulation and platelet aggregation were investigated using diluted whole blood and platelet rich plasma (PRP) solution prepared from human and rat blood, respectively. Blood coagulation was monitored by using a whole blood impedance aggregometer and titanium dioxide nanoparticle (10, 20, and 40 ppm) did not show any effect on the coagulation both in human and in rat blood. When platelet aggregation was measured by turbidometric method after addition of titanium dioxide nanoparticles to PRP solution with final concentrations of 1, 5 and 10 ppm. no aggregation was observed.

• 한국식품과학회지
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• 제28권4호
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• pp.684-688
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• 1996

전통식품인 된장으로부터 혈소판 응집 저해활성을 갖는 항혈전 펩타이드를 탐색하고자 하였다. 증류수로 추출한 된장액을 한외 여과하여 얻은 분자량 3,000 dalton 이하의 여액에 대하여, SD흰쥐의 세척혈소판 (washed platelet)을 이용하여 ADP 자극으로 유도되는 혈소판응집의 저해정도를 aggregometer에서의 탁도로 측정하였을 때, $96\;{\mu}g/ml$로 처리시 90% 가량의 응집 저해효과가 확인되었다. 추출물을 Dowex 50W X-2 강양이온 교환칼럼을 이용하여 pyridine-formic acid 완충액의 pH (2.8-5.0) 및 몰농도(0.1-3.0M)를 단계별로 증가시키면서 용출시켜 19개의 획분(No.B-18)으로 분리하였다. 이들 획분의 활성을 microplate를 이용한 방법으로 측정하였을 때, 전체적으로 앞의 방법보다는 감도가 낮게 나타났으나 모든 분획에서 응집억제 효과가 확인되었다. 이때 용량반응 곡선으로부터 구한 각 획분의 $IC_{50}$은 $10-1,000\;{\mu}g/ml)$의 범위를 보였으며, 대부분의 획분들은 양성대조구인 RGDS $(IC_{50},\;205\;{\mu}g/ml)$보다 높은 활성을 나타내었다. 또한, 후반부의 염기성 획분$(IC_{50},\;10-20\;{\mu}g/ml)$에서 된장추출물$(IC_{50},\;30\;{\mu}g/ml)$보다 활성이 높게 나타났다. 이들 중 활성이 가장 높은 16번 획분을 아미노산 분석한 결과, 펩타이드 부분에 histidine, arginine, alanine 등이 높은 비율로 존재하였다.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.887-893
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• 2005

The aggregability of red blood cells (RBCs) was determined by laser backscattering light analysis in a microfluidic channel. Available techniques for RBC aggregation often adopt a rotational Couette-flow using a bob-and-cup system for disaggregating RBCs, which causes the system to be complex and expensive. A disposable microfluidic channel and vibration generating mechanism were used in the proposed new detection system for RBC aggregation. Prior to measurement, RBC aggregates in a blood sample were completely disaggregated by the application of vibration-induced shear. With the present apparatus, the aggregation indexes of RBCs can be measured easily with small quantities of a blood sample. The measurements with the present aggregometer were compared with those of LORCA and the results showed a strong correlation between them. The aggregability of the defibrinogenated blood RBCs is markedly lower than that of the normal RBCs. The noble feature of this design is the vibration-induced disaggregation mechanism, which can incorporate the disposable element that holds the blood sample.

• Korea-Australia Rheology Journal
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• 제20권4호
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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.