Objective: Whether single low shear stress can result in atherosclerosis without hyperliposis-diet in vivo or not is unknown. Methods: Based on an electromagnetic blood flow meter and a method to determine the pulsati...Objective: Whether single low shear stress can result in atherosclerosis without hyperliposis-diet in vivo or not is unknown. Methods: Based on an electromagnetic blood flow meter and a method to determine the pulsatile shear stress from blood flow rate waveform and its software,we developed an in vivo pulsatile blood flow rate-shear stress determining system.The left external carotid arteries of 20 adult New Zealand white rabbits were ligated and the rabbits were fed with a standard chow for 2,4,8 or 12 weeks,then the common carotid arteries of 2 sides in each rabbit were harvested for morphologic test. Results: The ligation reduced pulsatile shear stress of left common carotid significantly,for example,τ_ mean changed from(21.16±7.17) dynes/cm 2 to(3.13±2.28) dynes/cm 2(p=2.176E-21),meanwhile,the pulsatile shear stress of right common carotid did not change significantly,which lasted more than 12 weeks.Atherosclerotic plaques were found after 8 and 12 weeks in pulsatile-low-shear-stress left(not normal-shear-stress right) common carotid arteries.Conclusion:Single pulsatile low shear stress can result in atherosclerosis.It supports the pulsatile low shear stress(not hypolipidemia) is the key risk factor for atherosclerosis.展开更多
Instruction Shear stress,caused by the parallel frictional drag force of blood flow,is a biomechanical force which plays an important role in the control of blood vessels growth and functions [1]. Clinical researches ...Instruction Shear stress,caused by the parallel frictional drag force of blood flow,is a biomechanical force which plays an important role in the control of blood vessels growth and functions [1]. Clinical researches had found out that atherosclerotic le-展开更多
Background Cardiovascular disease has become a major cause of death worldwide.Atherosclerosis is the pathological basis of many cardiovascular diseases.It is well established that hemodynamics also play an important r...Background Cardiovascular disease has become a major cause of death worldwide.Atherosclerosis is the pathological basis of many cardiovascular diseases.It is well established that hemodynamics also play an important role in endothelial cell mediated atherosclerotic development.In the process of inflammatory reaction,the damage of vascular endothelial cells is the initial link,and various factors can cause damage of endothelial cells.The change of shear stress is considered to be one of the important factors.In the body,vascular endothelial cells are constantly exposed to blood flow.Flow conditions critically regulate endothelial cell functions in the vasculature.Shear stress not only influences the endothelial cell morphology,migration,differentiation and proliferation,but also regulates the expression of proteins in the endothelial cells.Reduced shear stress resulting from disturbed blood flow can drive the development of vascular inflammatory lesions and promote the formation of atherosclerosis.In the present study,the objective of our study is the comprehensive identification of CX3CR1/NF-κB signaling pathway involved in low shear stress(LSS)-induced inflammation in HUVECs through protein profiling and cell function experiment.Methods Human umbilical vein endothelial cell was cultured onglass slides and placed in a parallel plate flow chamber.M199 culture medium was used for low laminar shear stress at 4.14 dyn/cm2,2 h for the testing group,CX3CR1 sh-RNA and NF-κB inhibitor PDTC are used to block the effects of CX3CR1 and P65.The expression levels of the protein were determined by western blot analysis.Mononuclear cell adhesion assays and scratch assays are used to detect cell adhesion and migration.Results Western blotting analyses revealed that compared with the controls,there is a significant increase in the expression of CX3CR1,nucleusP65,intercellular adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1)and Interleukin-6(IL-6),while the expression of cytosolic P65 and IκB was significantly reduced in human umbilical vein endothelial cells(HUVECs)treated with LSS.CX3CR1 Sh-RNA was use to reveal its effect on LSS-induced inflammation.Further,specific NF-κB P65 inhibitors(PDTC)were used to reveal the downstream NF-κB P65 exclusively involved in LSS-induced inflammation in HUVECs,this effect can be abrogated by CX3CR1 sh-RNA and NF-κB inhibitors.Monocyte adhesion assay and scratch test revealed LSS promotes adhesion of monocytes and migration of cells,this effect can be abrogated by CX3CR1 sh-RNA and NF-κB inhibitors.LSS is involved in the expression of adhesion moleculesand chemokines,which are important for the initiation of endothelial inflammation-related atherosclerosis.Conclusions The activation of CX3CR1/NF-κB signaling pathway induced by low shear stress in endothelial cells may lead to the future therapeutic targets of atherosclerotic inflammation.展开更多
With Zunyi CINRAD/CD Doppler radar data and other data,a hail wind and heavy rainfall in short time occurred on July 10,2008 in northern Guizhou Province was analyzed in this study.The results showed that the system w...With Zunyi CINRAD/CD Doppler radar data and other data,a hail wind and heavy rainfall in short time occurred on July 10,2008 in northern Guizhou Province was analyzed in this study.The results showed that the system was affected by the southward of cold air pressure in a low-shear vortex zone.Echo monomer initially developed and arranged along the shear line,and there was hail weather in echo location with intense development.Before the hail shooting,the strongest echo value was 60-65 dBz.When the hail shooting,the low-elevation echo intensity sharply increased to 55-60 dBz with echo height of 11-15 km and VIL values>35 kg/m2,and its echo distribution showed band characteristics of vortex.When the vortex center moved to the original echo,echo intensity increased,resulting in a profound and lasting convergence of cyclones,and hail or strong wind occurred on the ground.Hail and strong short-term precipitation in towns of northern Renhuai might be related to the left inverted U-terrain.Echoes from Yongxing and Yuquan in Meitan,Xuekong and Xitou in Renhuai were the supercell echoes,and other regional hail shooting echoes were strong multi-monomer echoes.展开更多
Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon i...Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon in south Asia is derived. The stress is on the influence of the flows on the formation,transformation and intensity of the monsoon in south Asia. The results show that the influence on the monsoon in south Asia is significantly different among the primary shear flow, the basic flow and the secondary shear flow.展开更多
针对半球共形阵体制下进行低空风切变检测时会受到强地杂波信号的干扰,导致风切变信号难以检测的问题,提出了一种基于空时自回归的直接数据域算法(Space-Time Autoregressive Direct Data Domain,D3AR)的低空风切变风速估计方法。该方...针对半球共形阵体制下进行低空风切变检测时会受到强地杂波信号的干扰,导致风切变信号难以检测的问题,提出了一种基于空时自回归的直接数据域算法(Space-Time Autoregressive Direct Data Domain,D3AR)的低空风切变风速估计方法。该方法首先将待检测距离单元的数据从空域、时域以及空时域进行信号对消处理;然后将处理后的数据矩阵描述为空时自回归(Autoregression,AR)模型并估计模型参数;再通过构造与杂波子空间正交的空间来实现对杂波的抑制,最后通过提取待检测单元的最大多普勒频率来估计风场速度。根据仿真结果显示,该方法有效地实现了地杂波抑制,并且能够精确估计风速。展开更多
文摘Objective: Whether single low shear stress can result in atherosclerosis without hyperliposis-diet in vivo or not is unknown. Methods: Based on an electromagnetic blood flow meter and a method to determine the pulsatile shear stress from blood flow rate waveform and its software,we developed an in vivo pulsatile blood flow rate-shear stress determining system.The left external carotid arteries of 20 adult New Zealand white rabbits were ligated and the rabbits were fed with a standard chow for 2,4,8 or 12 weeks,then the common carotid arteries of 2 sides in each rabbit were harvested for morphologic test. Results: The ligation reduced pulsatile shear stress of left common carotid significantly,for example,τ_ mean changed from(21.16±7.17) dynes/cm 2 to(3.13±2.28) dynes/cm 2(p=2.176E-21),meanwhile,the pulsatile shear stress of right common carotid did not change significantly,which lasted more than 12 weeks.Atherosclerotic plaques were found after 8 and 12 weeks in pulsatile-low-shear-stress left(not normal-shear-stress right) common carotid arteries.Conclusion:Single pulsatile low shear stress can result in atherosclerosis.It supports the pulsatile low shear stress(not hypolipidemia) is the key risk factor for atherosclerosis.
基金supported by grants from the National Natural Science Foundation of China,Nos10732070,10702043,30970703,10972140 and 30470432
文摘Instruction Shear stress,caused by the parallel frictional drag force of blood flow,is a biomechanical force which plays an important role in the control of blood vessels growth and functions [1]. Clinical researches had found out that atherosclerotic le-
基金supported by a project grant from the National Natural Science Foundation of China ( 31860261)
文摘Background Cardiovascular disease has become a major cause of death worldwide.Atherosclerosis is the pathological basis of many cardiovascular diseases.It is well established that hemodynamics also play an important role in endothelial cell mediated atherosclerotic development.In the process of inflammatory reaction,the damage of vascular endothelial cells is the initial link,and various factors can cause damage of endothelial cells.The change of shear stress is considered to be one of the important factors.In the body,vascular endothelial cells are constantly exposed to blood flow.Flow conditions critically regulate endothelial cell functions in the vasculature.Shear stress not only influences the endothelial cell morphology,migration,differentiation and proliferation,but also regulates the expression of proteins in the endothelial cells.Reduced shear stress resulting from disturbed blood flow can drive the development of vascular inflammatory lesions and promote the formation of atherosclerosis.In the present study,the objective of our study is the comprehensive identification of CX3CR1/NF-κB signaling pathway involved in low shear stress(LSS)-induced inflammation in HUVECs through protein profiling and cell function experiment.Methods Human umbilical vein endothelial cell was cultured onglass slides and placed in a parallel plate flow chamber.M199 culture medium was used for low laminar shear stress at 4.14 dyn/cm2,2 h for the testing group,CX3CR1 sh-RNA and NF-κB inhibitor PDTC are used to block the effects of CX3CR1 and P65.The expression levels of the protein were determined by western blot analysis.Mononuclear cell adhesion assays and scratch assays are used to detect cell adhesion and migration.Results Western blotting analyses revealed that compared with the controls,there is a significant increase in the expression of CX3CR1,nucleusP65,intercellular adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1)and Interleukin-6(IL-6),while the expression of cytosolic P65 and IκB was significantly reduced in human umbilical vein endothelial cells(HUVECs)treated with LSS.CX3CR1 Sh-RNA was use to reveal its effect on LSS-induced inflammation.Further,specific NF-κB P65 inhibitors(PDTC)were used to reveal the downstream NF-κB P65 exclusively involved in LSS-induced inflammation in HUVECs,this effect can be abrogated by CX3CR1 sh-RNA and NF-κB inhibitors.Monocyte adhesion assay and scratch test revealed LSS promotes adhesion of monocytes and migration of cells,this effect can be abrogated by CX3CR1 sh-RNA and NF-κB inhibitors.LSS is involved in the expression of adhesion moleculesand chemokines,which are important for the initiation of endothelial inflammation-related atherosclerosis.Conclusions The activation of CX3CR1/NF-κB signaling pathway induced by low shear stress in endothelial cells may lead to the future therapeutic targets of atherosclerotic inflammation.
文摘With Zunyi CINRAD/CD Doppler radar data and other data,a hail wind and heavy rainfall in short time occurred on July 10,2008 in northern Guizhou Province was analyzed in this study.The results showed that the system was affected by the southward of cold air pressure in a low-shear vortex zone.Echo monomer initially developed and arranged along the shear line,and there was hail weather in echo location with intense development.Before the hail shooting,the strongest echo value was 60-65 dBz.When the hail shooting,the low-elevation echo intensity sharply increased to 55-60 dBz with echo height of 11-15 km and VIL values>35 kg/m2,and its echo distribution showed band characteristics of vortex.When the vortex center moved to the original echo,echo intensity increased,resulting in a profound and lasting convergence of cyclones,and hail or strong wind occurred on the ground.Hail and strong short-term precipitation in towns of northern Renhuai might be related to the left inverted U-terrain.Echoes from Yongxing and Yuquan in Meitan,Xuekong and Xitou in Renhuai were the supercell echoes,and other regional hail shooting echoes were strong multi-monomer echoes.
文摘Using the equatorial balanced model and the low-corder spectral method to consider the effect of the basic flow, the primary and secondary shear flows, the nonlinear equation describing the winter and summer monsoon in south Asia is derived. The stress is on the influence of the flows on the formation,transformation and intensity of the monsoon in south Asia. The results show that the influence on the monsoon in south Asia is significantly different among the primary shear flow, the basic flow and the secondary shear flow.
文摘针对半球共形阵体制下进行低空风切变检测时会受到强地杂波信号的干扰,导致风切变信号难以检测的问题,提出了一种基于空时自回归的直接数据域算法(Space-Time Autoregressive Direct Data Domain,D3AR)的低空风切变风速估计方法。该方法首先将待检测距离单元的数据从空域、时域以及空时域进行信号对消处理;然后将处理后的数据矩阵描述为空时自回归(Autoregression,AR)模型并估计模型参数;再通过构造与杂波子空间正交的空间来实现对杂波的抑制,最后通过提取待检测单元的最大多普勒频率来估计风场速度。根据仿真结果显示,该方法有效地实现了地杂波抑制,并且能够精确估计风速。
