Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall.In our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses.In order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow conditions.The numerical models were created based on our previous experimental studies.The simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion tube.The present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.
[Objective] To extract the effective component rosmarinic acid from Folium perillae,study preparation technology and quality control of rosmarinic acid injection and provide test basis for hemorheological drug development and clinic application.[Method]The coarse powder of Folium perillae(40 μm)was lixiviated with hot water and acidized to make aqueous extracts.Rosmarinic acid from the aqueous mixture was extracted with Ethyl Acetate.And Et Ac was evaporated to obtain primary product.The injection was purified by pH adjustment.Concentration of rosmarinic acid in the injection was detected by high performance liquid chromatography(HPLC).Contents of tannin,resin and oxalate were eliminated according to the Chinese Pharmacopeia(2005 edition).Stability,irritation,haemolyticus,LD50 and thermogenic substance of this injection were also detected.[Result]The content of rosmarinic acid in Folium perillae injection is 2.81 mg/ml,and the content of LD50 was 406.82 mg/kg.This injection was consistent with the stipulation of Chinese Pharmacopeia(2005 edition).[Conclusion]The preparation technology of this experiment was reasonable.The stable qualities of the prepared injection meet the injection requirement.
Both clinical and post mortem studies indicate that, in humans, the carotid sinus of the carotid artery bifurcation is one of the favored sites for the genesis and development of atherosclerotic lesions. Hemodynamic factors have been suggested to be important in atherogenesis. To understand the correlation between atherogenesis and fluid dynamics in the carotid sinus, the blood flow in artery was simulated numerically. In those studies, the property of blood was treated as an incompressible, Newtonian fluid. In fact, however, the blood is a complicated non-Newtonian fluid with shear thinning and viscoelastic properties, especially when the shear rate is low. A variety of non-Newtonian models have been applied in the numerical studies. Among them, the Casson equation was widely used. However, the Casson equation agrees well only when the shear rate is less than 10 s-1. The flow field of the carotid bifurcation usually covers a wide range of shear rate. We therefore believe that it may not be sufficient to describe the property of blood only using the Casson equation in the whole flow field of the carotid bifurcation. In the present study, three different blood constitutive models, namely, the Newtonian, the Casson and the hybrid fluid constitutive models were used in the flow simulation of the human carotid bifurcation. The results were compared among the three models. The results showed that the Newtonian model and the hybrid model had verysimilar distributions of the axial velocity, secondary flow and wall shear stress, but the Casson model resulted in significant differences in these distributions from the other two models. This study suggests that it is not appropriate to only use the Casson equation to simulate the whole flow field of the carotid bifurcation, and on the other hand, Newtonian fluid is a good approximation to blood for flow simulations in the carotid artery bifurcation.
Yubo FanWentao JiangYuanwen ZouJinchuan LiJunkai ChenXiaoyan Deng
