Study on Fluid Shear Flow on Osteoblast-like Cells in Their Tensile Loading Experiments

In vitro cell loading experiments are used to investigate stimulation of strain to cellular proliferation. As the flowing conditions of culture fluid in loading systems has been little known, strictly people can not detect the influence of strain to cellular proliferation exactly because shear flow can enhance cell proliferation either. Based on the working principle and cyclic loading parameters, we simplify Navier-Stokes equation to describe the flow of culture fluid on substrates of uniaxial and equi-biaxial fiat tensile loading systems and four point bending system. With approximate solutions, the distributions of velocity field and wall shear flow to cells are gained. Results show: shear flows are zero in the middle (or fixed point or line) of substrate for all systems, and they get larger proportionally to distance from middle and substrate elongate; the shear flow on the substrate of four point bending system is much greater than those of others. This shear flow in four point bending system, confirmed by Owan, I., et al with OPN mRNA increase in their experiment, could cause more influence to osteoblast-like cells than that caused by strain. We estimate the average magnitude of shear stress in Owan‘ s device, the results are consistent with other experimental data about shear flow. In conclusion our study makes it possible to differentiate the influence of strain on cellular proliferation to that of shear flow in loading experiments with the devices mentioned above quantitatively.     

一种用于体外培养细胞的静磁场加载装置

磁性附着体均存在漏磁,应用于患者口腔中时将对邻近组织施加一定强度的静磁场。磁性附着体磁场对机体组织的生物学效应尚鲜见研究报道。本研究研制了一套细胞静磁场加载装置,并模拟磁性附着体静磁场对体外培养人牙周膜细胞加载。该装置能产生恒定的静磁场且磁场强度可调,体积小巧,可对培养皿、培养孔板等多种规格细胞培养器皿中的细胞加载静磁场,便于对细胞的多项生物学指标进行研究。对人牙周膜细胞加载静磁场的结果显示该装置可以有效地对体外培养细胞进行不同强度、不同时间的静磁场加载。该装置为研究静磁场细胞生物学效应提供了必要的手段。     

外扰作用下细胞内稳态鲁棒性实验研究

内稳态是一种重要的生理现象,是生物反应动态平衡的结果.以内皮细胞为对象,用H2O2作为外源扰动剂,建立一种外扰作用下细胞内钙稳态鲁棒性的分析方法,包括以控制理论Lyapunov及鲁棒性理论为基础的扰动前稳态点和稳定域、扰动后状态转移和稳定鲁棒域.通过对照和1、10、30、50、100 μmol/L 5种不同剂量H2O2...     

灌注速度对悬浮细胞在微流道中运动的影响

目的 建立细胞灌注培养有限元模型,研究不同灌注速度对悬浮细胞运动的影响.方法 利用COMSOL Multiphysics建立细胞和微流道二维模型并进行网格划分,根据灌注速度不同分为3组,分别为u0=0.196 mm/s、u1=0.117mm/s、u2=0.04mm/s,利用流固耦合模块进行计算.结果 微流道中流场分布比...     

动物体内磁场与红细胞电泳速度的实验研究

用稀土元素铈（Ｃｅ）、钴（Ｃｏ）等制成磁注射剂（浓度为３００ｇ／Ｌ）作为磁疗新方法，将０．１～０．２ｍｌ（３０～６０ｍｇ）该注射剂注入小鼠股动、静脉周围，并使其在４７５．２Ａ／ｍ电磁场下感应成永磁体，其体表磁场强度为０．０８～０．１６ｍＴ，体内强度为１．２５～１．６ｍＴ。用断尾取血法测定小鼠红细胞电泳速度，结果发现：电泳速度明显增快，与对照组、空白组比较，有非常显著的差异（Ｐ＜０．０１）。提示：弱磁场的生物效应能提高红细胞表面的电荷，使细胞间的排斥力加强，减少红细胞聚集发生的可能性；另一方面，动、静脉血液循环流经磁场时，受磁力线的切割而导致血浆分子结构发生改变，从而使血液粘度降低，血流速度加快。因此，体内磁场可作用于某些疾病，起到活血化瘀、改善微循环的作用。     

脐动脉血流测定与胎儿脐带绕颈

目的 :研究脐血流测定对脐带绕颈的预后评估。方法 :对 2 8例B超诊断为脐带绕颈的胎儿产前进行了脐动脉血流S/D值的测定 ,追踪观察围产儿出生时羊水性状、Apgar评分、脐带绕颈情况。 结果 :2 8例B超诊断为脐带绕颈的胎儿产时有 5例未发现脐带绕颈 ;而且S/D值 <3 .0的 2 4例 ,围产结局良好 ;S/D值 >3 .0的 4例 ,娩出时均是脐带绕颈很紧 ,其中 3例羊水粪染 ,Apgar评分均 <7分。结论 :S/D值可作为衡量脐带绕颈对胎儿危害程度的一种方法 ,结合B超为临床决定分娩方式提供依据     

Macrophage-Like Cells as Research Tools in Transfer Experiments

Transfer experiments with macrophages are only possible to a limited extent in mice as this kind of experiment usually requires large numbers of macrophages. The usual source of macrophages is the peritoneal cavity, which yields on the average only 2–20 × 10⁶ macrophages per mouse. Instead, we now use for transfer experiments macrophage-like cells, such as the macrophage tumors WEHI-3, J774A and P388D₁. To prevent replication after transfer, the cells can be treated with mitomycin-C. Our data illustrate that these macrophage-like cells can co-operate with sensitized lymphocytes in the eradication of lymphosarcoma cells in a fashion similar to macrophages (1). The vast amount of available data on properties of these cells (2) will allow to correlate their macrophage properties with in-vivo function.     

一种体外贴壁细胞应变加载装置的研制

目的开发一套新型的应变加载装置,用于贴壁细胞力学生物学研究。方法该装置基于基底形变加载技术,采用可控制编程器驱动步进器,引起硅橡胶小室变形,实现多单元大应变的细胞加载;研制该装置,检测机械性能;建立硅橡胶小室的三维模型,利用有限元技术对硅橡胶小室进行仿真,分析该小室的应变场均匀性问题;采用该装置对骨髓间充质干细胞(bone marrow stromal cells,BMSCs)加载5%机械应变,频率0.5 Hz,2 h/d,持续5 d,并在倒置显微镜下观察细胞形态的变化。结果所研制的适用于体外细胞加载装置可对3组细胞加载基底实现最大至50%机械单向应变;在10%应变范围内,硅橡胶小室底部的均匀应变场面积占比保持在50%以上,保证了细胞受力均匀; BMSCs形态发生明显变化,排列方向趋于垂直主应变加载方向。结论该装置运行可靠,应变范围宽,频率可调,操作方便,可同时对多组细胞培养基底进行应变加载,为细胞力学生物学研究提供了便利条件。