应力培养对血管内皮细胞形态结构的影响

为在体外形成一个抗流动切应力作用能力强的单层内皮细胞，在１５ｄｙｎｅｓ／ｃｍ＾２切应力的条件下，培养内皮细胞２４ｈ。细胞内皮细胞中央出现应力纤维，Ｇ０／Ｇ１期细胞增加，这一现象提示，在切应力条件下培养内皮细胞，可增强细胞抗血流冲击的能力。     

切应力对培养人脐静脉内皮细胞形态的影响

用可模拟生理及超生理切应力的平行板模拟循环流动装置进行实验，发现模拟生理脉动切应力及超生理脉动切应力均可使培养人脐静脉内皮细胞沿液体流动方向伸长。采用计算机半自动图像分析系统半定量处理，进一步发现内皮细胞伸长程度与切应力大小及作用时间呈正相关、并且，模拟超生理切应力对内皮细胞形态的影响较生理脉动切应力大。     

流动切应力对培养的血管内皮细胞形态的影响

为探索培养的血客内皮细胞承受流体冲击的能力，以便在人工心脏瓣膜表面形成一个抵抗血流切应力作用强的血管内皮细胞层，在我们研制的内皮细胞切应力反应测试装置上，观察了培养在盖玻片表现的牛主动脉内皮细胞形成单层细胞后在切应力分别在１５ｄｆｙｍｅｓ／ｃｍ＾２２４小时和１１５ｄｙｍｓ／ｃｍ＾２８小时作用下细胞的形态张脱落情况。     

血流切应力影响动脉内皮形态重建的在体研究

目的　探讨动脉血流受阻后壁切应力 (WSS)变化对内皮细胞形态适应性重建的影响。　方法　 6 0只实验兔建立颈总动脉血流减小模型 ,在术后 0～ 30d 8个不同时相点 ,制作血流减小后的颈总动脉铺片 ,应用银染及荧光素标记的鬼笔环肽特染方法 ,显微镜及共聚焦激光扫描显微镜下观察动脉内皮细胞 (AEC)的形状及骨架纤维肌动蛋白 (F actin)的变化 ,计量AEC结构参数。　结果　WSS减小后 12h即导致AEC张力纤维的减少或消失 ,形状由棱形变为椭圆形 ,计量显示 ,AEC形状指数、长宽比分别较正常对照显著增大、减小 (P <0 0 1)。术后 7d改变最为显著 ,外周带微丝增粗 ,中央张力纤维完全消失 ,细胞排列无明显定向。随着WSS的递增 ,部分细胞可见张力纤维 ,AEC形状指数在逐渐减小 ,长宽比增大。　结论　AEC的形态随WSS的动态变化而改变 ,提示WSS是导致AEC形态结构重建的主要因素。     

红细胞-固面撞击损伤的实验研究

研究不同撞击速度下,红细胞损伤情况。采用自由落体撞击法进行血液撞击实验,通过血液流变仪对撞击样本进行分析。结果表明,人体血液作为一种特殊的流体,在较高的撞击速度下红细胞有可能发生破裂导致溶血,当撞击速度达到6m/s以上时,红细胞受损破裂趋势增大。血泵的额定转速内,红细胞撞击破碎而造成的损伤并不明显。     

原子力显微镜对红细胞表面形态的研究

扫描电镜已不能满足细胞精细结构研究的需要，原子力显微镜克服了扫描电镜在这方面的不足，并在生物领域得到应用。本实验就是用原子力显微镜研究红细胞损伤，可观察到被内皮素损伤的红细胞的三维图象，发现金属硫蛋白有保护红细胞的作用。     

猪单个核细胞对自身红细胞溶血活性的影响

以简易法测定后得出结论:猪单个核细胞对自身红细胞溶血活性的影响属自发的细胞毒功能;IFN—α和IL—2等重要的免疫调节因子对溶血活性有增强作用,该活性和NK活性密切相关。同时证明,建立简便的测定法是经济可行的。     

流体切应力对血管内皮细胞的作用

20世纪80年代生物医学科学领域出现了一个新的热点一血管内皮细胞的形态和机能的研究。不仅因为血管内皮细胞的异常与心脑血管病、肿瘤、免疫性疾病、出血、辐射、移植排斥反应等等重要疾病发病和防治有关,而且和组织工程、人工器官等的开发有着密切关系。所以该领域一开始就吸引着国内外很多学者的兴趣和关注,该领域的炽热状态可能会维持到下世纪中叶。一、血管内皮细胞的形态和功能内皮细胞（endothelialcell,EC）是衬贴在心血管内脏面的单层鳞状细胞。厚约0．1－1μm,大小为（10－50）μm×（25－40）μm,多角形,全身血管内皮细胞…     

毛细血管内红细胞流变形态的平面观

作者应用微循环显微录像系统。对活体大白鼠肠系膜毛细血管内红细胞流变形态的平面观察,结果提示:红细胞流变形态的改变与其通过的血管管径大小有关;各种原因所致的红细胞变形能力降低,将导致严重的微循环障碍。     

在恒定切应力场中切应力损伤癌细胞的研究

本文报道了流体切应力对癌细胞的破坏。实验结果表明:在恒定切应力场中,切应力对癌细胞有极强烈的破坏作用。在假定同株癌细胞群体与切应力作用有关的各性质是均一的条件下,可以认为存活率与时间的关系为指数关系,即存活率V=e(-kt)(k为常数,t为时间),此结论与实验结果十分吻合。本文研究了癌细胞在恒定切应力场中存活率与温度的关系,揭示了癌细胞存活率的变化反映了膜的流变性质的变化,膜的相变导致了存活率的剧烈变化。并通过实验证实细胞的骨架系统影响着细胞的变形能力。本文还探讨了切应力破坏癌细胞的机制,提出了切应力破坏癌细胞的模型,并指出切应力对细胞膜的破坏是致死癌细胞的主要原因。     

磁力驱动轴流血泵溶血实验和动物实验

目的对研制开发的一种新型的磁力外驱动轴流式心室辅助血泵的血液相容性能进行测试。方法利用特制血袋作为模拟循环管道,羊血作为循环介质,采用标准溶血指数衡量体外溶血实验性能。通过3只山羊12h在体实验衡量其在体适应性。结果实验测得轴流血泵体外实验标准溶血指数(NIH)为(0.158±0.043)mg/L。3例实验动物12h在体辅助无机械故障,血泵辅助后实验动物血液中游离血红蛋白(FHb)开始上升,最高达到164.8mg/L。结论磁力外驱动轴流血泵实验结果比较理想,值得进一步改进。     

心室辅助装置引发血管性血友病因子损伤的检测方法研究

目的由于血液成分血管性血友病因子(von Willebrand factor,vWF)的机械损伤现象发现和研究较晚,至今仍然定义模糊且缺乏相关的评价标准,非常不利于心室辅助装置(ventricular assist device,VAD)的创新设计与发展。本文通过研究分析,提出检测vWF受高剪切应力损伤的实验方法。方法人血作为基础血样,离心式血泵BPX-80剪切前后的猪血作为测试血样,通过免疫印迹法,将电泳分离的vWF转移到膜上,然后用特异性抗体检测膜上vWF多聚体的分子量分布情况,根据vWF分子量的灰度值比值,定量分析vWF多聚体的机械损伤,整个实验过程包括制胶、电泳、转印、免疫反应和显色5部分。结果得到条带清晰完整且容易区分的vWF分子量分布图。其中健康人血vWF高分子量、中分子量、低分子量区域的灰度值比值与文献中健康人血vWF的实际比值相一致。BPX-80血泵剪切猪血中高分子量vWF与未经剪切的猪血高分子量vWF灰度值的比值随时间呈下降趋势,表明BPX-80血泵剪切对猪血中vWF的降解情况。结论成功设计并建立了vWF多聚体分析实验方法,为此后制定vWF机械损伤的标准化体外评价方案提供重要参考。     

Numerical studies of blood shear and washing in a continuous flow ventricular assist device

The third prototype of a continuous flow ventricular assist device (CF3) is being developed and tested for implantation in humans. The blood in the pump flows through a fully shrouded four bladed impeller (supported by magnetic bearings) and through small clearance regions on either side of the impeller. Computational fluid dynamics (CFD) solutions for this flow have been obtained by using TascFlow, a software package available from AEA Technology, UK. These flow solutions have been used to estimate the shear stresses on the blood in the pump and, hence, to minimize hemolysis. In addition, the solutions are informative for achieving a design that will provide good washing of the blood to minimize the possibility of stagnation points that can lead to thrombosis. This study presents numerical studies of these phenomena in the CF3. The calculated shear rate results are compared with values published in the open literature. The comparisons indicate that hemolysis will not be a problem with CF3, which is in agreement with preliminary experimental measurements. Flow studies are being conducted to determine the optimal size of the clearance regions.     

Leakage flow rate and wall shear stress distributions in a biocentrifugal ventricular assist device

In previous studies, the radial and tangential leakage flow velocities in the gap between the rotating impeller and the pump casing of a biocentrifugal ventricular assist device (VAD) model were obtained by hot wire. Based on the velocities obtained, the leakage flow rate through the clearance gap between the impeller and the stationary casing, as well as the wall shear stress distributions on the inner surface of the stationary casing, can be determined. By integrating the radial velocities numerically, the leakage flow rate through the clearance gap was found to be 6.43 x 10(-4) m3/s under operating conditions, which is 25.7% of the inlet flow. This is equivalent to approximately 1.7 L/min in the prototype. The leakage flow rate was found to be 5.22 x 10(-4) m3/s and 3.66 x 10(-4) m3/s under fully opened and fully closed conditions, respectively. The double volute design significantly affected wall shear stress distributions, with the high wall shear stress region concentrated at the beginning of the splitter plate under all three flow conditions. In contrast, the high wall shear stress region could only be observed at the cutwater in the fully closed condition. The highest wall shear stress was found to be 44.1 Pa, which is much lower than the threshold values that cause hemolysis. On the other hand, the lowest wall shear stress was found to be 21.31 Pa. This wall shear stress level is much higher than the shear stress required to disrupt aggregates of blood cells and platelets. These findings explain why hemolysis and thrombosis are at the low level in the clearance gap of this VAD.     

流体切应力对血管内皮细胞基因表达的影响

血液产生的切应力可以引起血管中的内皮细胞发生生物物理、生化和基因调控水平上的反应,从而调节内皮的结构和功能。当内皮细胞受到的切应力发生变化时,即可引起细胞基因表达上的变化,从而可能引发一些常见的心血管疾病。对切应力调控内皮细胞基因表达机制的研究,有助于找到治疗以上疾病的临床方法。综述了切应力对内皮细胞基因表达的影响及其调控机制,并对其在临床治疗、小口径人工血管构建和药物设计等方面的应用前景进行了展望。     

流体剪切力作用下无间隙连接成骨细胞阵列内的钙响应

目的 研究间隙连接和ATP在力致胞间钙传递过程中各自的作用。方法 首先应用微模式化方法建立无间隙连接的成骨细胞阵列,再利用流动腔对细胞施加流体剪切力,观察并分析细胞的钙响应特征参数。结果 细胞间无物理连接时,仍会出现多个钙响应峰,但第1峰的响应时间与有间隙连接时相比明显加长。除去胞外或胞内钙时,只有约40%的细胞发生钙响应,且单峰与多峰约各占一半。阻断胞外ATP通路后,只有约20%的细胞有钙响应,且大多为单峰。结论 细胞间的间隙连接不存在时,ATP是介导细胞间钙传递的主要途径,说明间隙连接不是细胞间力致钙响应的必需途径。     

Particle image velocimetry measurements of blood velocity in a continuous flow ventricular assist device

The third prototype of a continuous flow ventricular assist device (CFVAD3) is being developed and tested for implantation in humans. The blood in the pump flows through a fully shrouded four-bladed impeller (supported by magnetic bearings) and through small clearance regions on either side of the impeller. Measurements of velocities using particle image velocimetry of a fluid with the same viscosity as blood have been made in one of these clearance regions. Particle image velocimetry is a technique that measures the instantaneous velocity field within an illuminated plane of the fluid field by scattering light from particles added to the fluid. These measurements have been used to improve understanding of the fluid dynamics within these critical regions, which are possible locations of both high shear and stagnation, both of which are to be avoided in a blood pump. Computational models of the pump exist and these models are currently being used to aid in the design of future prototypes. Among other things, these models are used to predict the potential for hemolysis and thrombosis. Measurements of steady flow at two operating speeds and flow rates are presented. The measurements are compared with the computed solutions to validate and refine, where necessary, the existing computational models.     

Effect of desmopressin on erythrocyte aggregation

Experiments on rats showed that desmopressin in doses recommended for single injections to humans increased erythrocyte aggregation. A close correlation between erythrocyte aggregation index and blood viscosity, on the one hand, and plasma content of acid glycosaminoglycans on the other was detected. Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 146, No. 9, pp. 301–303, September, 2008     

Effects of continuous flow left ventricular assist device support on skin tissue microcirculation and aortic hemodynamics

Continuous flow ventricular assist devices (CFVADs) are thought to be the next generation of circulatory assist devices. With many now in various stages of development or clinical trial, it is important that the physiologic aspects of these pumps be critically analyzed. In this study, 15 calves were divided into two groups. One group received a CFVAD, and the other a sham implant. Two additional animals were used in an acute study to examine aortic blood flow patterns from a CFVAD. Tissue perfusion was measured on all animals before surgery and then weekly thereafter. Before surgery, there was no difference in hemodynamics or tissue perfusion between studied animals. Postoperatively, CFVAD animals had statistically significant increased diastolic pressure. Significantly decreased pulse pressure, pulse index, and tissue perfusion were also observed in CFVAD animals. Results from the flow pattern studies suggested that at moderate levels of pump support (40-75%), the amount of blood flow distal to the outflow graft anastomosis decreased approximately 25% because of increased regurgitant blood flow in the aorta. These results suggest that the diminished tissue perfusion is likely due to changes in aortic hemodynamics and provide some insight into the distribution of flow from CFVADs.