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OBJECTIVE@#To study the effect of gradient shear stress on platelet aggregation by microfluidic chip Technology.@*METHODS@#Microfluidic chip was used to simulate 80% fixed stenotic microchannel, and the hydrodynamic behavior of the stenotic microchannel model was analyzed by the finite element analysis module of sollidwork software. Microfluidic chip was used to analyze the adhesion and aggregation behavior of platelets in patients with different diseases, and flow cytometry was used to detect expression of the platelet activation marker CD62p. Aspirin, Tirofiban and protocatechuic acid were used to treat the blood, and the adhesion and aggregation of platelets were observed by fluorescence microscope.@*RESULTS@#The gradient fluid shear rate produced by the stenosis model of microfluidic chip could induce platelet aggregation, and the degree of platelet adhesion and aggregation increased with the increase of shear rate within a certain range of shear rate. The effect of platelet aggregation in patients with arterial thrombotic diseases were significantly higher than normal group (P<0.05), and the effect of platelet aggregation in patients with myelodysplastic disease was lower than normal group (P<0.05).@*CONCLUSION@#The microfluidic chip analysis technology can accurately analyze and evaluate the platelet adhesion and aggregation effects of various thrombotic diseases unde the environment of the shear rate, and is helpful for auxiliary diagnosis of clinical thrombotic diseases.
Subject(s)
Humans , Microfluidics , Platelet Adhesiveness , Platelet Aggregation , Blood Platelets/metabolism , Platelet Aggregation Inhibitors/pharmacology , Platelet Activation/physiology , ThrombosisABSTRACT
Objective To examine the antiplatelet effect of ticagrelor by microfluidic chip and flow cytometry under shear stress in vitro. Methods Microfluidic chip was used to examine the effect of ticagrelor on platelet aggregation at the shear rates of 300/s and 1500/s.We adopted the surface coverage of platelet aggregation to calculate the half inhibition rate of ticagrelor.The inhibitory effect of ticagrelor on ADP-induced platelet aggregation was verified by optical turbidimetry.Microfluidic chip was used to construct an in vitro vascular stenosis model,with which the platelet reactivity under high shear rate was determined.Furthermore,the effect of ticagrelor on the expression of fibrinogen receptor (PAC-1) and P-selectin (CD62P) on platelet membrane activated by high shear rate was analyzed by flow cytometry. Results At the shear rates of 300/s and 1500/s,ticagrelor inhibited platelet aggregation in a concentration-dependent manner,and the inhibition at 300/s was stronger than that at 1500/s (both P<0.001).Ticagrelor at a concentration ≥4 μmol/L almost completely inhibited platelet aggregation.The inhibition of ADP-induced platelet aggregation by ticagrelor was similar to the results under flow conditions and also in a concentration-dependent manner.Ticagrelor inhibited the expression of PAC-1 and CD62P. Conclusion We employed microfluidic chip to analyze platelet aggregation and flow cytometry to detect platelet activation,which can reveal the responses of different patients to ticagrelor.
Subject(s)
Humans , Ticagrelor/pharmacology , Platelet Aggregation Inhibitors/pharmacology , Flow Cytometry/methods , Microfluidics , Platelet AggregationABSTRACT
Objective To investigate platelet aggregation on glass surface under physiological flow condition. Methods The polydimethylsiloxane (PDMS)-glass microchannel chips were fabricated by soft lithography. Anti-coagulant human peripheral whole blood was flowed through the microchannel chip at flow shear rate of 300 s-1 and 1 500 s-1, respectively. The fluorescence images of platelet aggregates formed on glass surface at the bottom of the microchannel were captured after 150 s using an inverted fluorescence microscope. The number of platelet aggregates, average size, surface coverage and average fluorescence intensity were quantified by image analysis. The glass surface was treated with oxygen plasma, BSA blocking or collagen modification to establish different surfaces for platelet aggregation. The hematocrit (Hct) of blood sample was adjusted, and the whole blood was treated with different anti-platelet agents. The platelet aggregation on glass surface was observed under the above experimental conditions. The platelet aggregations in healthy people and diabetic patients were also analyzed. Results Under the flow condition, platelet aggregation on glass surface was three-dimensional. Platelet aggregation was dependent on wall shear rate, the hydrophilicity of glass surface and Hct, and was mainly regulated by GPIIb/IIIa-fibrinogen and ADP-P2Y12 receptor pathways. The aggregation of platelets on the glass surface could also reflect the high activity of platelets in diabetic patients. Conclusions At the flow conditions of 300 s-1 and 1 500 s-1, platelet aggregation on glass surface is related to flow rate, protein adsorption, platelet related receptors and platelet activation state. In this study, a new model for microfluidic platelet function analysis without additional adhesion protein modification was established, and it could be used for clinical evaluation of platelet function.
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Objective • To examine the carotid viscoelasticity by using ultrasonic shear wave dispersion (USWD) technique, and to preliminarily analyze its correlation with blood flow shear rate. Methods • Forty-five patients of General Surgery Department of Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine from December 2018 to January 2019 were recruited, and divided into the elder group (≥ 50 years old) and the younger group (<50 years old) according to the median age. The carotid viscoelasticity of the patients was examined by USWD technique and the indexes were obtained, including carotid shear wave elasticity (SWER), shear wave dispersion (SWDR), blood flow maximum shear rate (SRmax) and mean shear rate (SRmean). The correlations between SWER, SWDR and blood flow shear rate were analyzed by Pearson correlation, respectively. Results • ① Compared with the younger group, the carotid artery SWER, SWDR, SRmax and SRmean of the patients in the elder group were lower (all P<0.05). ② The SWER and SWDR of carotid artery of all patients were positively correlated with SRmax and SRmean, respectively (all P<0.05). Conclusion • Carotid arterial viscoelastic index based on USWD technique is closely related to the blood flow shear rate, which is expected to provide a new perspective for the study of carotid arterial diseases.
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Objective To investigate the shear rate and VWF-A1-mediated platelets calcium response. Methods Flou-4 AM was used as the fluorescent indicator of intracellular calcium, and the intracellular calcium concentrations of adherent platelets on VWF-A1 with different concentrations at different shear rates were detected by parallel plate flow chamber system combined with fluorescence microscope. The effect of shear stress and chemical signaling on intensity and speed of calcium response was also analyzed. Results VWF-A1 specifically mediated platelet adhesion and calcium response under flow. The shear rate and molecular concentrations had positive regulation of platelets activation ratio and negative regulation of delay time of calcium response. Compared with static conditions, the activation ratio was increased by 37 times at shear rate of 500 s-1. When the concentration of VWF-A1 was increased from 60 mg/L to 240 mg/L, the delay time of calcium response was shortened by 10 s. Conclusions The shear rate could modulate the calcium response of platelets in cooperation with VWF-A1. The result of this study will be helpful to deepen the understanding about the process of hemostatic reaction of platelet coagulation in bloodstream.
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Objective To develop a simple microfluidic chip technology for analyzing platelet adhesion and aggregation under the condition of physiological flow .Methods The basic structure of the proposed microfluidic chip was a straight microchannel , where a sample pool and an outlet were located on each side respectively .The fluid dynamic behavior ,of the fluid in the microchannel was analyzed by theoretical calculation and finite element numerical analysis software ANSYS . The microchannel was first coated with type Ⅰ collagen protein.Then,blood flowed through the microchannel at 200 s-1 venous physiological shear rate and 1000 s-1 arterial physiological shear rate respectively .The behavior of the fluorescence labeled platelet adhesion and aggregation was recorded by fluorescence microscopy .Results Theoretical calculation and finite element numerical analysis showed that the microchannel with a width of 700 μm and a height of 70 μm ( aspect ration 10:1 ) had a uniform fluidic shear rate distribution .Compared with those at the 200 s-1 shear rate, the initial adhesion time, aggregation rate and the maximum surface cover rate of the platelet were significantly reduced at the 1000 s-1 shear rate ( P<0.05 ) .At the 1000 s-1 shear rate, tirofiban, an anticoagulant drug , significantly reduced the platelet aggregation in a concentration-dependent manner and the IC 50 was 23.8 nmol/L.Conclusion The technology developed in this paper can dynamically assay platelet adhesion and aggregation under the condition of physiological flow . The proposed microfluidic methods have the advantage of simple implementation and low sample cousumpation , and can be used for point-of-care detection of human platelet function , assay of the efficacy of anticoagulant drugs and for inspection of the thrombin behaviors of small animal models .
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Objective To develop a simple microfluidic chip technology for analyzing platelet adhesion and aggregation under the condition of physiological flow .Methods The basic structure of the proposed microfluidic chip was a straight microchannel , where a sample pool and an outlet were located on each side respectively .The fluid dynamic behavior ,of the fluid in the microchannel was analyzed by theoretical calculation and finite element numerical analysis software ANSYS . The microchannel was first coated with type Ⅰ collagen protein.Then,blood flowed through the microchannel at 200 s-1 venous physiological shear rate and 1000 s-1 arterial physiological shear rate respectively .The behavior of the fluorescence labeled platelet adhesion and aggregation was recorded by fluorescence microscopy .Results Theoretical calculation and finite element numerical analysis showed that the microchannel with a width of 700 μm and a height of 70 μm ( aspect ration 10:1 ) had a uniform fluidic shear rate distribution .Compared with those at the 200 s-1 shear rate, the initial adhesion time, aggregation rate and the maximum surface cover rate of the platelet were significantly reduced at the 1000 s-1 shear rate ( P<0.05 ) .At the 1000 s-1 shear rate, tirofiban, an anticoagulant drug , significantly reduced the platelet aggregation in a concentration-dependent manner and the IC 50 was 23.8 nmol/L.Conclusion The technology developed in this paper can dynamically assay platelet adhesion and aggregation under the condition of physiological flow . The proposed microfluidic methods have the advantage of simple implementation and low sample cousumpation , and can be used for point-of-care detection of human platelet function , assay of the efficacy of anticoagulant drugs and for inspection of the thrombin behaviors of small animal models .
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Objective To analyze the relation between carotid intima-media thickness (IMT) and the shear rate (SR),and to explore the effect of SR on IMT in the patients with end-stage renal disease (ESRD)and the kidney transplant recipients (KTR).Methods From March 2014 to December 2015,31 KTR and 31 patients with ESRD supported by hemodialysis and 84 control subjects underwent an carotid ultrasound in Shanghai General Hospital affiliated to Shanghai Jiaotong University.Bilateral carotid IMT and SR were measured.The differences of IMT and SR in three groups were compared by single factor analysis of variance.SNK-q test was used to compare the two groups.The correlation between SR and bilateral IMT was analyzed by linear regression analysis in healthy control group,ESRD group and KTR group.Results On the right,in ESRD,KTR and control group,the IMTs were (561.9± 147.7) μm,(480.5±90.3) μtm and (529.7±131.80) μtm respectively.Compared with KTR and control group,the IMT on right was thickest in ESRD,but there was no significant difference between KTR and control group in right IMT.On the left,the IMTs were (517.5± 164.7) μm,(506.7± 126.3) μm and (467.0± 106.4) μm in control group,ESRD and KTR,respectively.Among groups,there was no significant difference.On the right,the SRs were (134.01 ±56.4) s-1,(133.4±43.7) s-1 and (175.8±68.3) s-1 in ESRD,KTR and control group,respectively.In ESRD and KTR groups,the SR of the right carotid artery was less than that of the control group,and had significant difference (q=3.133,P=0.002;q=3.470,P ＜ 0.001).There was no significant difference in right SR between ESRD and KTR.On the left,the SRs were (146.3±55.9) s-1,(138.5±43.8) s-1 and (154.7±60.8) s-1 in ESRD,KTR and control group,respectively,and had no significant difference.There was linear negative correlation between SR and IMT in healthy control group,ESRD group and KTR group,respectively (right:r=-0.384,-0.082,-0.454;left:r=-0.572,0.223,-0.276,all P ＜ 0.05).Conclusions The IMT was thickened in ESRD group,but got thinning after successful kidney transplantation.The SR played a vital role in this alteration of IMT.
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Objective：The aim of this study is to obtain information for setting a common shear rate for the viscosimetry of thickened liquids.Materials & Methods：The panelists (healthcare professionals involved in dysphagia) drank five maltose syrups, and organized them in the order of viscosity based on their pharyngeal sense. Then, they drank three thickened liquids, i.e., 1.4% and 0.95% xanthan gum (XAN) solutions, and 1.4% guar gum (GUA) solution, and aligned them with the maltose syrups. We carried out the test twice using different concentrations of maltose syrups and obtained 126 answers. Results：Of all panelists, 77% could correctly arrange the five maltose syrups in the order of viscosity. The answers of the panelists who could serialize the five maltose syrups and the two XAN solutions were as follows. There were few answers that corresponded to shear rate of less than 11 sec<sup>-1</sup> for each of the thickened liquids. Meanwhile, most frequently answers corresponded to the shear rates of 61-140 sec<sup>-1</sup>, 80-240 sec<sup>-1</sup>, 210-620 sec<sup>-1</sup> for 1.4% XAN, 0.95% XAN, and 1.4 GUA solutions, respectively. Conclusion：The common shear rate for the viscosimetry of thickened liquids was not equivalent to the shear rate of 3 sec<sup>-1</sup> historically adopted in Japan；it was at least 50 sec<sup>-1</sup> according to the results of the sensory evaluation.
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Objective To study the different effects from different concentration ratios of polymorphonuclear neutrophil (PMN) to tumor cell (TC) on the process of tumor cell adhesion to endothelial cell (EC) in shear flow. Methods PMNs and TCs with different concentration ratios (PMN-TC ratio) were added into the parallel plate flow chamber, and changes in the numbers of transient and accumulative adhered TCs on ECs at different shear rates (50 s-1，100 s-1，200 s-1) were analyzed. Results The transient and accumulative adhesion of TCs on ECs at PMN-TC ratio of 3︰1 significantly increased as compared to that at PMN-TC ratio of 1︰1, especially under high shear flow condition (100 s-1 and 200 s-1). Moreover, in the 5 minute-observation period, the effect of PMN-TC ratio on TC adhered to ECs occurred earlier when the shear rate increased. Conclusions The increase of PMN-TC concentration ratio can promote TC adhesion to ECs in shear flow, and the research findings provide significant references for studying TC metastasis in blood vessels and the target therapy of tumors.
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A disfagia se caracteriza por uma disfunção no processo de deglutição, sinal prevalente de doenças degenerativas como esclerose múltipla e doença de Parkinson. Alimentos de textura modificada e bebidas espessadas são tradicionalmente utilizados no auxílio para o tratamento clínico da disfagia. Assim, este trabalho objetivou desenvolver uma formulação de espessante alimentar com valor nutricional agregado, e avaliar sua eficiência em diferentes alimentos líquidos (leite integral, sucos de maçã, uva e laranja), sob diferentes condições de tempo de preparo (10 e 120 minutos e 24 horas) e temperatura ambiente (25°C) e refrigerada (10°C). A formulação foi composta de concentrado proteico de soro, mix de vitaminas e minerais e goma guar como agente espessante. Os valores obtidos para a viscosidade mostraram diferença estatisticamente significativa (P<0,05) entre os tempos de espessamento, sendo que as viscosidades no tempo de 10 minutos e após 24 horas variaram, respectivamente, 58±3cP a 180±2cP na consistência de néctar; de 310±4Cp a 1084±3cP na consistência de mel e 844±14 a 2848±22cP na consistência de pudim. No entanto, a maioria das bebidas permaneceu dentro dos padrões internacionais sugeridos pela National Dysphagia Diet (NDD), para a consistência de alimentos destinados a pacientes disfágicos.
Dysphagia is characterized by a dysfunction of the swallowing process, being a prevalent symptom of degenerative diseases such as multiple sclerosis and Parkinson's disease. Foods with modified texture and thickened beverages are traditionally used in the clinical treatment of dysphagia. This study aims to develop a formulation of food thickener with value nutritional aggregate, as well as evaluate its action on various liquid food , under different conditions of preparation time (10 and 120 minutes and 24 hours) temperature (25°C) and refrigeration (10°C). The formulation was composed of whey protein concentrate (WPC), mix of vitamins and minerals and guar gum as a thickening agent. The values obtained for the viscosity showed a difference statistically significant at the 5% level, between the times of thickening, ranging from 58±3CP to 2848±3CP, as well as between different samples tested when compared to each other for the same time. However, viscosity measurements showed that the most beverages are in international standards suggested by the National Dysphagia Diet (NDD), for consistency of food for dysphagia patients.
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Objective To investigate the correlation of intima-media thickness (IMT) of the lower peripheral arteries and maximal shear rate (SR) in diabetic (DM) patients and to analyze the related risk factors.Methods A total of 84 diabetic patients and 46 controls were recruited in the study.Color Doppler ultrasonography technique was applied to observe the IMT,diameter(D) and hemodynamics of the lower peripheral arteries and the comparison with biochemical parameters was carried out in order to reveal their correlation to the pathological changes of vascular in DM patients.ResultsIn DM group,the SR was lower than that in control group (P＜0.05).The risk factors related to the lower peripheral arteries of DM patients also were significant difference to that of control group (P＜0.05).Conclusion The decrease of SR in diabetes patients can cause the thicker IMT,which is one of the important factors leading to atherosclerosis and is correlated to various risk factors for metabolic syndrome.
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Guaran was transformed into grafted polymer using vinyl monomer. The vinyl monomer used for the graft was acrylamide. The grafting was initiated through the formation of free radical centers on the polymer backbone by oxidation of guaran with cerium (IV) in nitric acid medium. The degree of grafting was varied by using varying amount of acrylamide vinyl monomer. The rheological properties of the guaran grafted polyacrylamide copolymer have been studied by varying the degree of grafting, time, concentration, temperature, spindle number and shear rate. Thermal Characteristics of the guaran-grafted polyacrylamide was studied using thermo gravimetric analysis under nitrogen atmosphere. The prepared copolymer was characterized by FTIR.
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O princípio da reometria é relativamente simples, e a construção de equipamentos para avaliação do comportamento reológico de materiais pode ser realizada com poucos investimentos. O presente trabalho teve por objetivos projetar e construir um reômetro capilar para caracterizar ingredientes e misturas utilizadas em alimentação animal. Durante os testes, observou-se atrito desprezível (0,20 a 0,01 por cento da força aplicada) entre pistão e cilindro e não se observou refluxo de amostra. A força necessária para o escoamento das amostras através do capilar foi de 986,02±52,05; 559,60±52,24 e 338,25±45,86N, para as amostras com 29,04±0,08, 31,91±1,01 e 34,98±0,30 por cento de umidade, respectivamente. A partir da fundamentação teórica de reologia de materiais, foi possível construir um reômetro fundamental utilizando materiais e operações simples de tornearia, com custo total de R$ 4.500,00.
The fundaments of rheometry are relatively simple, and the construction of equipments to measure the rheological behavior of materials can be accomplished with small investment. The aim of this paper is to describe the design and construction of a capillary rheometer to characterize feed ingredients. The force required to extrude and maintain sample flow was 986.02±52.05; 559.60±52.24 and 338.25±45.86N for the samples with 29.04±0.08, 31.91±1.01 and 34.98±0.30 percent moisture, respectively, with negligible (0.20 to 0.01 percent of total force) friction among moving parts, neither any mass reflux between piston and cylinder. Based on the fundaments of rheology, it was possible to build a capillary rheometer using simple materials and operations usually available in an engineering laboratory at a total cost of R$ 4,500.00.
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The objective of the current study is to investigate the effect of physical vibration on blood viscosity. The "capillary tube viscometer concept" is applied to measure blood viscosity. Blood viscosity can be measured at the minimum shear rate of 12 s(-1) by the capillary tube viscometer. To examine the effect of physical vibration on blood viscosity, the vibrations are produced by contact with an electronic speaker. The frequencies of vibration are varied from 0 to 1000 Hz. The experimental results show that blood viscosity can be effectively reduced by applying vibration. Blood viscosity decreases as much as 10~12 % by applying vibration.