微悬臂梁阵列在细胞牵引力测量中的应用

精确测量细胞牵引力的大小及分布对细胞生物学、组织工程等研究具有重要意义.近年来,基于生物微机电系统技术制作的高深宽比聚二甲基硅氧烷 (PDMS) 微悬臂梁阵列作为细胞牵引力测量传感器受到广泛关注.不同于传统基于连续基质的测量方法,细胞在致密、垂直、离散的微悬臂梁阵列顶端贴附并延展、迁移,引起微悬臂梁形变.通过对扫描电子显微镜图像处理,细胞牵引力测量精度可以达到数十 nN/m.我们综述了基于微悬臂梁阵列细胞牵引力传感器测量方法,重点论述了实验原理、制作工艺和细胞实验,并讨论了微悬臂梁阵列结构倒塌机理.     

基于BioMEMS微柱矩阵的细胞牵引力测量

本文综述了基于生物微机电系统 (BioMEMS) 微柱矩阵的细胞牵引力测量方法。细胞牵引力对于许多生物学过程非常关键,决定着许多细胞功能,包括细胞迁移、细胞外基质构建、信号传导等。细胞通过纳牛顿量级的牵引力使细胞外基质局部变形来探测其机械顺从性。精确测量细胞牵引力大小及分布对细胞生物学、组织工程等生物医学研究具有重要意义。BioMEMS 的进步使高深宽比聚二甲基硅氧烷 (PDMS) 微柱矩阵被开发出来作为传感器用来探测细胞纳牛力学及在体外研究细胞的机械性质。细胞贴附在微柱矩阵顶端,并且在多个柱顶端间延展迁移,这个过程会造成微柱发生如垂直悬臂梁般的弯曲形变。采用这种致密、垂直、离散微柱矩阵结构替代传统测量的连续介质,通过对微柱形变的显微图像处理,细胞牵引力可以被直接定性定量测量,精度可以达到数十 nN/?m 量级。首先简要总结了传统细胞牵引力测量方法,接下来着重于基于 BioMEMS 微柱矩阵的测量方法,论述了其原理、制作工艺、表面处理及细胞实验等。最后对微柱矩阵结构的坍塌问题进行了讨论。     

光寻址单细胞传感器的设计及药物检测的研究

本研究提出了一种基于光寻址电位传感器（Light-Addressable Potentiometric Sensor，LAPS）的新型单细胞传感器。该传感器可以通过移动激发对作为敏感元件的单个细胞进行寻址测量，克服了基于场效应管和微电极阵列的细胞传感器中测量位点固定、细胞定位培养困难等缺欠，探索了这种光寻址单细胞传感器的结构设计和检测活细胞电生理特性的可行性。最后分析了该传感器在药物检测方面的应用。实验结果表明了该细胞传感器在单细胞电生理研究和药物分析中是可行的。     

基于线阵电荷耦合器件的数字差分式肌张力传感器

基于线阵电荷耦合器件(charge coupled device,CCD)设计了一种数字差分式肌张力传感器,以悬臂梁为弹性元件,线阵CCD为检测元件,将张力变化转化为激光光斑在CCD感光窗口上的位置变化,实现了肌张力的数字差分式测量。采用两组线阵CCD对称式设计,使传感器具有差动式测量的优点;位移变化是以线阵CCD像元的数量来体现,使传感器具有数字化测量的特点。结果证明,测量方法具有数字差分的特征,显著降低了传感器的非线性误差和迟滞,适用于微张力的数字化测量。     

微机器人结肠镜样机及离体肠道试验研究

为了对结肠进行微创无创检查，依据仿生学原理，使用微细加工技术，开发了一种基于电磁蠕动的仿蚯蚓微机器人结肠镜样机，进行了离体肠道试验。微机器人结肠镜使用电磁直线驱动器，运动单元之间由万向节连接，机器人整体柔软灵活。头部通过形状记忆合金控制行走方向和成像方向。在试验中，对机器人的运动效率、运动能力进行了深入的分析，测量了运动速度、牵引力。设计并制造出样机，进行了猪结肠离体实验，结果表明机器人结肠镜运动可靠、控制方便，该研究对机器人结肠镜进人临床应用具有一定的参考价值。     

利用微悬臂梁传感对瘦肉精进行非标记检测

目的 利用微悬臂梁传感技术对瘦肉精抗原抗体的特异性结合进行检测。 方法 将巯基化的瘦肉精抗体通过自组装修饰到微悬臂梁的金面,在加入不同浓度的瘦肉精标准样品的过程中,通过光杠杆原理监测微悬臂梁的实时弯曲信号。巯基化瘦肉精抗体的活性和微悬臂梁上抗原抗体的结合得到酶联免疫吸附（ELISA）实验的验证。结果 该系统能够检测至少1ng/ml浓度的瘦肉精标准样品,而且具有很强的选择性,在对照实验中加入不含瘦肉精的1μg/ml氯霉素溶液没有响应。另外,瘦肉精抗原抗体的结合导致微悬臂梁产生压应力,而且微悬臂梁表面应力的改变与样品浓度的对数成线性关系。 结论 利用微悬臂梁传感技术对瘦肉精的检测是可行的。     

基于微机械薄膜变形镜的人眼视网膜成像研究

高分辨率视网膜图像能够为视网膜疾病的早期诊断、治疗、人眼视觉的科学研究提供重要依据。本研究探讨人眼像差和高分辨率视网膜图像的像差补偿技术,着重H-S传感器像差测量、波前重构算法、变形镜控制算法,提出了基于微机械薄膜变形镜的自适应光学系统闭环控制。通过校正模拟眼的静态像差和人眼的动态像差的实验表明,能够达到减小人眼像差、获得人眼视网膜细胞的初步图像,为进一步获取视网膜各层细胞图像提供了理论和实验依据。     

基于光纤传感器的透析穿刺针头漏血检测方法研究

基于光导纤维设计了一种检测血红细胞浓度的光纤传感器,并将光纤传感器用于透析穿刺针头的漏血检测,提出了一种漏血检测的新方法。通过动物血样实验,分别测量了红、绿、蓝三色光为光源的光纤传感器的输出曲线,对比分析了三色光源的光纤传感器的输出特性,证明蓝光源光纤传感器检测灵敏度最高;通过志愿者血样实验测量了蓝光源光纤传感器输出特性曲线,并确定了报警阈值范围。结果证明,以蓝光为光源的光纤传感器漏血检测方法具有灵敏度高和安全可靠的优点,能够准确检测透析穿刺针头的微漏血量。此种漏血检测报警装置能够在透析过程中对穿刺针头的微量漏血进行实时监测,避免透析中发生漏血事故。     

基于微机电系统运动传感器在人体运动测量中的应用**

背景：基于微机电系统的运动传感器以其安装简易、使用便利、成本低廉的特点给人体运动测量变革带来了契机。 目的：分析总结运动传感器中适合人体运动测量的几型传感器,以及利用这些运动传感器取得的研究成果。 方法：应用计算机检索CNKI和ISI数据库中2005/2011-08关于基于微机电系统运动传感器技术的文章,在标题和摘要中以“微机电系统、运动传感器、人体运动”或“micro electro mechanical systems sensor,human motion,human movement”为检索词进行检索。选择内容与微机电系统运动传感器技术在人体运动测量中的应用相关的文章,且尽量选择近5年发表或发表在权威杂志的文章。 结果与结论：初检得到180篇文献,根据纳入标准选择34篇文章进行综述。人体运动测量中对各种运动传感器技术的关注和应用越来越多,运动传感器能够迅速简便地检测人体的运动信息,而其捕获的运动信息可广泛运用于各种临床领域。随着软硬件技术的不断发展将成为人体运动测量的主流手段。 关键词：运动传感器;微机电系统;人体运动测量;测量;应用;进展 doi:10.3969/j.issn.1673-8225.2012.09.041     

细胞在三维结构中牵张力的产生及其应用北大核心

背景:贴壁生长的细胞通过肌动-肌球蛋白之间的相互作用对细胞外基质或基底施加一定的牵张力,该过程与许多生理和病理过程密切相关。目的:综述了目前几种主要的细胞牵张力技术的基本原理及应用情况。方法:第一作者以"细胞牵张力、细胞力学"检索CNKI数据库、万方数据库,以"Cell traction force、Biomechanics"检索PubMed数据库、SpringerLink数据库。收入有关细胞牵张力测量方法的研究,排除重复研究。通过阅读,最终选取30篇文献进行综述,其中中文1篇,英文29篇。结果与结论:细胞牵张力的测量方法主要有3种:硅胶薄膜测量法、细胞牵张力显微镜技术、微组装悬臂梁。准确估算细胞牵张力,将进一步拓展对细胞-细胞以及细胞-微环境之间的力学作用等诸多基本问题的理解。     

Immunolocalization of ubiquitin in muscle biopsies of patients with inclusion body myositis and oculopharyngeal muscular dystrophy.

In 10/10 inclusion body myositis (IBM) patients and 2/2 oculopharyngeal muscular dystrophy (OPMD) patients, vacuolated muscle fibers contained darkly stained ubiquitin (Ub)-immunoreactive cytoplasmic inclusions. By electronmicroscopy, Ub-immunoreactive material was strictly localized to the 15-21 nm pathologic cytoplasmic tubulofilaments (CTFs). None of 18 control muscle biopsies contained the Ub-immunoreactive inclusions that are typical for IBM and OPMD. Thus, (a) finding that CTFs are ubiquitinated places their protein in the Ub-mediated turnover pathway and provides their first molecular marker; (b) easy accessibility, as compared to the central nervous system, of muscle tissue containing ubiquitinated inclusions should be advantageous for biochemical and molecular studies and may provide information important to both systems.     

Efficient nonlinear registration of 3D images using high order co-ordinate transfer functions

There is an increasing interest in image registration for a variety of medical imaging applications. Image registration is achieved through the use of a co-ordinate transfer function (CTF) which maps voxels in one image to voxels in the other image, including in the general case changes in mapped voxel intensity. If images of the same subject are to be registered the coordinate transfer function needs to implement a spatial transformation consisting of a displacement and a rigid rotation. In order to achieve registration a common approach is to choose a suitable quality-of-registration measure and devise a method for the efficient generation of the parameters of the CTF which minimize this measure. For registration of images from different subjects more complex transforms are required. In general function minimization is too slow to allow the use of CTFs with more than a small number of parameters. However, provided the images are from the same modality and the CTF can be expanded in terms of an appropriate set of basis functions this paper will show how relatively complex CTFs can be used for registration. The use of increasingly complex CTFs to minimize the within group standard deviation of a set of normal single photon emission tomography brain images is used to demonstrate the improved registration of images from different subjects using CTFs of increasing complexity.     

Light and electron microscopic localization of beta-amyloid protein in muscle biopsies of patients with inclusion-body myositis.

In 11 of 11 inclusion-body myositis (IBM) patients, including one hereditary case, vacuolated muscle fibers contained large and multiple small inclusions immunoreactive for beta-amyloid protein (beta AP). All IBM muscle biopsies had characteristic cytoplasmic tubulo-filaments (CTFs) by electron microscopy. None of 14 control muscle biopsies contained the beta AP immunoreactive (IR) inclusions characteristic of IBM. On the light microscopy level, beta AP-IR inclusions colocalized with ubiquitin immunoreactivity. By immunogold electronmicroscopy, beta AP immunoreactivity was localized to a) amorphous, poorly defined structures, b) dense floccular material, c) clusters of loosely packed amyloidlike fibrils 6-8 nm in diameter, and d) poorly defined loose fibrillar structures 6-8 nm in diameter. beta AP immunoreactive structures were often in proximity to CTFs, but CTFs themselves never contained beta AP-IR. Our study provides the first demonstration of beta AP accumulations in abnormal human muscle. This finding suggests that in addition to Alzheimer's disease, Down syndrome, and Dutch-type hereditary cerebrovascular amyloidosis, beta AP may play an important role in the pathogenesis of other diseases, including ones outside the central nervous system, for example, IBM.     

Efficient nonlinear registration of 3D images using high order co-ordinate transfer functions

There is an increasing interest in image registration for a variety of medical imaging applications. Image registration is achieved through the use of a co-ordinate transfer function (CTF) which maps voxels in one image to voxels in the other image, including in the general case changes in mapped voxel intensity. If images of the same subject are to be registered the co-ordinate transfer function needs to implement a spatial transformation consisting of a displacement and a rigid rotation. In order to achieve registration a common approach is to choose a suitable quality-of-registration measure and devise a method for the efficient generation of the parameters of the CTF which minimize this measure. For registration of images from different subjects more complex transforms are required. In general function minimization is too slow to allow the use of CTFs with more than a small number of parameters. However, provided the images are from the same modality and the CTF can be expanded in terms of an appropriate set of basis functions this paper will show how relatively complex CTFs can be used for registration. The use of increasingly complex CTFs to minimize the within group standard deviation of a set of normal single photon emission tomography brain images is used to demonstrate the improved registration of images from different subjects using CTFs of increasing complexity.     

Different aggregation states of a nuclear localization signal‐tagged 25‐kDa C‐terminal fragment of TAR RNA/DNA‐binding protein 43 kDa

The mechanism and cause of motor neuronal cell death in amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disorder, are unknown; gain of function of oligomers and aggregation of misfolded proteins, including carboxyl‐terminal fragments (CTFs) of TAR RNA/DNA‐binding protein 43 kDa (TDP‐43), have been proposed as important causative factors in the onset of ALS. We recently reported that a nuclear localization signal (NLS)‐tagged 25‐kDa CTF of TDP‐43 (TDP25) could decrease the cell‐death proportion compared with that promoted by TDP25. Here, we show oligomeric states of NLS‐TDP25 and its detailed localization property using super‐resolution fluorescence microscopy, FRET, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy analysis. NLS‐TDP25 efficiently formed a nucleolar cap structure via RNA binding in the presence of actinomycin D, but TDP25 did not. Although cytoplasmic inclusion bodies including TDP25 had a disordered and immobile structure, NLS‐TDP25 in the nucleolus was ordered and dynamic. In the diffuse state, TDP25 formed fewer oligomers and interacted with the molecular chaperone, HSP70; however, NLS‐TDP25 formed oligomers. These results suggested that NLS‐tagged TDP25 can change its structure to use ordered oligomeric but nontoxic state. Moreover, the structure of ordered oligomers as well as nuclear sequestration may be important in mediating cytotoxicity in ALS pathology.     

gamma-Secretase can cleave amyloid precursor protein fragments independent of alpha- and beta-secretase pre-cutting

Abeta is the major component of amyloid in the brain in Alzheimer's disease and is derived from an amyloid precursor protein (APP) by the sequential proteolytic processing of two putative proteases, called beta- and gamma-secretase. To clarify the mechanism of gamma-secretase processing, we created constructs contained the C-terminal domain of APP and analyzed the processing in COS-1 cells. We found that C-terminal fragments (CTFs) containing a short extra N-terminal region before the beta-secretase cleavage site were directly processed at gamma-secretase cleavage site. This suggests that gamma-secretase cleavage occurs independently and is not dependent on alpha- and beta-secretase cleavage.     

Calpastatin modulates APP processing in the brains of β-amyloid depositing but not wild-type mice

We report that neuronal overexpression of the endogenous inhibitor of calpains, calpastatin (CAST), in a mouse model of human Alzheimer's disease (AD) β-amyloidosis, the APP23 mouse, reduces β-amyloid (Aβ) pathology and Aβ levels when comparing aged, double transgenic (tg) APP23/CAST with APP23 mice. Concurrent with Aβ plaque deposition, aged APP23/CAST mice show a decrease in the steady-state brain levels of the amyloid precursor protein (APP) and APP C-terminal fragments (CTFs) when compared with APP23 mice. This CAST-dependent decrease in APP metabolite levels was not observed in single tg CAST mice expressing endogenous APP or in younger, Aβ plaque predepositing APP23/CAST mice. We also determined that the CAST-mediated inhibition of calpain activity in the brain is greater in the CAST mice with Aβ pathology than in non-APP tg mice, as demonstrated by a decrease in calpain-mediated cytoskeleton protein cleavage. Moreover, aged APP23/CAST mice have reduced extracellular signal-regulated kinase 1/2 (ERK1/2) activity and tau phosphorylation when compared with APP23 mice. In summary, in vivo calpain inhibition mediated by CAST transgene expression reduces Aβ pathology in APP23 mice, with our findings further suggesting that APP metabolism is modified by CAST overexpression as the mice develop Aβ pathology. Our results indicate that the calpain system in neurons is more responsive to CAST inhibition under conditions of Aβ pathology, suggesting that in the disease state neurons may be more sensitive to the therapeutic use of calpain inhibitors.     

Two-dimensional manipulation of confluently cultured vascular endothelial cells using temperature-responsive poly(N-isopropylacrylamide)-grafted surfaces

Temperature-responsive hydration/dehydration changes in surface-grafted poly(N-isopropylacrylamide) (PIPAAm) were utilized for hydrophilic/hydrophobic surface property alterations in cell culture. In this report, we utilized PIPAAm-grafted surfaces to recover confluently-cultured vascular endothelial cells as coherent monolayers from this cell culture substrate and to transfer to new cell culture substrates. For this purpose, we used two different methods to recover and transfer cell monolayer cultures: (1) chitin membranes used as an apical side cell support during cultured cell transfer, allowing cell basal side reattachment to new culture substrates after transfer; and (2) a cell culture insert? (porous PET) used as both a support as well as new substrate, allowing basal surfaces of cultured cells to be exposed to the medium after transfer. In both cases, all cells grown on PIPAAm-grafted surfaces detach completely with maintenance of basement membrane-like structure. Recovered cells attach to the second culture surfaces, covering more than 60% of the new substrate, and retain approximately 90% viability and their original function as judged from tissue-type plasminogen activator secretion. This technique could be utilized to prepare novel bioartificial organs as well as cell co-culture systems by multi-layering different cell types to mimic tissue structures for tissue engineering.