Nanostructure of collagen fibrils in human nucleus pulposus and its correlation with macroscale tissue mechanics

Collagen fibrils are the main structural components of the nucleus pulposus tissue in the intervertebral discs. The structure–property relationship of the nucleus pulposus (NP) tissues is still unclear. We investigated the structure of individual collagen fibrils of the NP and evaluated its correlation with the bulk mechanical properties of the tissue. Collagen fibrils were extracted from the NP of discs retrieved from adolescents during scoliosis correction surgery, and the extracts were confirmed by SDS‐PAGE. The diameters of the individual collagen fibrils were measured through atomic force microscopy, and the compressive mechanical properties of the tissues were evaluated by confined compression. The correlations between the nanoscale morphology of the collagen fibrils and the macroscale mechanical properties of the tissues were evaluated by linear regression. The SDS‐PAGE results showed that the fibril extracts were largely composed of type II collagen. The mean diameter of the collagen fibrils was 92.1 ± 26.54 nm; the mean swelling pressure and compressive modulus of the tissues were 6.15 ± 4.3 kPa and 1.23 ± 0.7 MPa, respectively. The mean fibril diameter had no linear correlation (R² = 0.30) with the swelling pressure of the tissues. However, it had a mild linear correlation with the compressive modulus (p = 0.023, R² = 0.68). This is the first study, to our knowledge, to evaluate the nanostructure of the individual collagen fibrils of the nucleus pulposus and its relationship with macroscale mechanical properties of the NP tissues. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:497–502, 2010     

大鼠上颌第一磨牙正畸移动中牙周膜神经PGP9.5的表达

目的：建立大鼠正畸牙移动模型,观察PGP9.5在牙周膜（PDL）神经中的表达及变化,探讨正畸力转化成神经元的反应的细胞调控机制。方法：成年雄性SD大鼠25只,随机分为5组：加力0、3、7、14、21天组,每组5只。上颌第一磨牙（URM1）施加50g近中向的拉力,按实验期限,分别取不同组大鼠含磨牙及其周围牙槽骨的组织块切片,进行PGP9.5免疫组化染色。镜下观察牙齿压力侧牙周膜神经纤维PGP9.5免疫阳性的变化情况,并进行灰度值分析、统计学方差分析和t检验。结果：压力侧的神经纤维的密度增加。在第7天牙槽骨表面出现类骨质的沉积;第21天根吸收陷窝处可见免疫阳性的牙周神经纤维。第3、7天牙周膜神经纤维PGP9.5的表达最强（P〈0.05）,之后神经的表达开始下降,牙周膜神经密度也逐渐恢复。结论：正畸加力使大鼠牙周膜神经中PGP9.5表达增强,PGP9.5调控神经肽的合成和分泌,可能是神经元细胞调控的重要机制。牙周膜神经在调节骨细胞活性和促进类骨质的形成,以及牙根吸收和修复等过程中可能也发挥重要作用。     

A Comparative Reliability and Performance Study of Different Stent Designs in Terms of Mechanical Properties: Foreshortening,Recoil, Radial Force,and Flexibility

This study seeks to improve the mechanical performance of stents by conducting reliability performance testing and finite element method (FEM)‐based simulations for coronary stents. Three commercially available stent designs and our own new design were tested to measure the factors affecting performance, specifically foreshortening, recoil, radial force, and flexibility. The stents used in the present experiments were 3 mm in working diameter and 18 mm of working length. The results of the experiments indicate that the foreshortening of stents A, B, C, and our new design, D, was equivalent to 2.25, 0.67, 0.46, and 0.41%, respectively. The recoil of stents A, B, C, and D was 6.00, 4.35, 3.50, and 4.36%, respectively. Parallel plate radial force measurements were A, 3.72 ± 0.28 N; B, 3.81 ± 0.32 N; C, 4.35 ± 0.18 N; and D, 4.02 ± 0.24 N. Radial forces determined by applying uniform pressure in the circumferential direction were A, 28.749 ± 0.81 N; B, 32.231 ± 1.80 N; C, 34.522 ± 3.06 N; and D, 42.183 ± 2.84 N. The maximum force of crimped stent at 2.2‐mm deflection was 1.01 ± 0.08 N, 0.82 ± 0.08 N, 0.92 ± 0.12 N, and 0.68 ± 0.07 N for each of stents A, B, C and D. The results of this study enabled us to identify several factors to enhance the performance of stents. In comparing these stents, we found that our design, stent D, which was designed by a collaborative team from seven universities, performed better than the commercial stents across all parameter of foreshortening, recoil, radial force, and flexibility.     

Improvement of the Tissue-adhesive and Sealing Effect of Fibrin Sealant Using Polyglycolic Acid Felt

Although fibrin sealant (FS) has an advantage of high biocompatibility, its adhesive force and sealing effect have been generally considered to be inadequate. In the present study, a high adhesive force and sealing effect were obtained by first rubbing fibrinogen solution into the target tissue, attaching polyglycolic acid (PGA) felt to the treated area, and finally spraying it with FS. This method was compared with three conventional FS application methods and a method using fibrin glue-coated collagen fleece. The adhesive force resulting from the present method was 12 times higher than that for the sequential application method, 4.5 times higher than the spray method, 2.5 times higher than the rubbing and spray method, and 2.2 times higher than the use of fibrin glue-coated collagen fleece. The high adhesive force of FS with PGA felt seemed to be due the high fibrin content of the fibrin gel (FG). Light and electron microscopic observations suggested that the formation of FG in closer contact with the muscle fibers was a factor contributing to this superior adhesive force. Comparison of the sealing effect of the present method with other methods using various biomaterials in combination with FS showed that the sealing effect of FS with PGA felt was 1.4 times higher that of polyglactin 910, 1.8 times that of polytetrafluoroethylene, and 6.7 times that of oxidized regenerated cellulose.     

原子力显微镜检测α-突触核蛋白转基因鼠线粒体微观结构的变化

目的 使用原子力显微镜检测α-突触核蛋白（α-synuclein,α-syn）转基因小鼠模型中,皮质线粒体表面微观结构的变化。方法 提取野生型和转基因小鼠皮质细胞线粒体,使用共聚焦显微镜检测其膜电势变化,使用原子力显微镜的敲击模式检测线粒体膜表面的微观结构。结果 JC-1染色法检测线粒体膜电势结果显示,转基因小鼠线粒体膜电势与野生组相比降低20.4%,差异有统计学意义（P<0.01）;原子力显微镜观察结果显示,转基因小鼠线粒体长度与野生组相比增加,表面光滑度减低,线粒体膜孔增多（P<0.05）。结论 α-Syn的转基因小鼠线粒体膜电势减低,线粒体膜完整性受到破坏。在原子力显微镜敲击模式下检测离体线粒体,能反映出转基因小鼠线粒体膜表面微观结构的变化。     

三种数字化分析算法测量咬合接触分布及面积的对比研究

目的:研究三种数字化分析算法测量石膏牙颌模型三维咬合接触分布及面积的检测效果,并与传统咬合分析方法进行比较,探究各数字化分析算法的特点和应用。方法:选取一副正常受试者的上、下颌石膏牙颌模型,使用3shape E4牙颌模型三维扫描仪进行数字化扫描得到数字模型,在三维测量分析软件Geomagic Studio 2013及Geomagic Qualify 2013中采用“三维偏差色阶图法”、“点云统计分析法”和“虚拟咬合纸法”三种数字化分析算法获得相应的三维咬合接触分布及面积,同时使用牙合记录硅橡胶法及咬合纸扫描法两种传统咬合分析方法获得咬合接触分布和面积。各方法的咬合检测阈值为100 μm,量化评价各数字化分析算法与传统咬合分析方法的检测结果。结果:上述五种方法所得的全牙列咬合接触分布的定性评价结果基本一致,三维偏差色阶图法、点云统计分析法、虚拟咬合纸法、牙合记录硅橡胶法和咬合纸扫描法所得到的总咬合接触面积分别为133.10 mm ²、142.08 mm ²、128.95 mm ²、163.31 mm ²、100.55 mm ²。三种数字化分析算法间的检测结果差异性不大,数字化方法与传统方法检测的总咬合接触面积有一定差异。结论:三种数字化分析算法均可提供较为可靠、准确的牙颌模型咬合接触分布及面积量化分析结果,可为口腔临床修复体数字化设计制作及咬合分析提供参考。     

导航监测下股骨旋转角度及胫骨截骨后内翻角度对下肢动态力线的影响

目的 在计算机导航系统监测下模拟全膝关节置换术,观察不同股骨假体旋转角度及胫骨内翻角度对下肢动态力线的影响。方法 应用计算机导航技术于假骨上模拟人工全膝关节置换术,分别设定在股骨侧假体外旋不足及股骨侧假体过度外旋的情况下,设定胫骨截骨后内翻为0°、3°、5°不同角度时,活动膝关节记录膝关节0°、30°、60°、90°时下肢力线角度并进行分析,得到其变化的趋势和规律。结果 在股骨假体外旋不足的情况下,随着胫骨截骨后内翻角度的逐渐增大,下肢机械轴线内翻角度随之减少(P＜0.05或＜0.01);在股骨假体外旋不足的情况下,相同的胫骨截骨后内翻角度,在0～90°区间内下肢机械轴线内翻角度逐渐减少(P＜0.05);在股骨假体过度外旋情况下,随着胫骨截骨后内翻角度的逐渐增大,下肢机械轴线内翻角度随之增大(P＜0.05或＜0.01);在股骨假体过度外旋情况下,相同的胫骨截骨后内翻角度,在0～90°区间内下肢机械轴线内翻角度逐渐增大(P＜0.05)。结论 股骨假体旋转角度及胫骨内翻角度是影响下肢力线的重要因素。     

Share control of surgery robot master manipulator guiding tool along the standard path

Recently, minimally invasive surgery (MIS) robotics enters the phase of autonomous operation. However, because of the high variability of the environment, conducting a fully autonomous surgery is still extremely difficult. This paper presents a share control system, the objective of which is to suggest the optimum path of tool guidance through the use of force on the master manipulator (hereinafter as master), meaning the surgeon's hand. Owing to this type of control, the surgeon has full control over the position of the tool the entire time and is supported by the system to better and faster guide the tool during surgery. The force should be felt by the surgeon but, simultaneously, must not hinder or impact the surgical process. Furthermore, the share control system presented in the paper can be turned on or off at any moment during surgery.     

Combined local impedance and contact force for radiofrequency ablation assessment

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Monitoring film coalescence from aqueous polymeric dispersions using atomic force microscopy: Surface topographic and nano-adhesion studies

The aim of the investigation was to develop the use of topographic and nano-adhesion atomic force microscopy(AFM) studies as a means of monitoring the coalescence of latex particles within films produced from a pharmaceutically relevant aqueous dispersion(Eudragit~?NE30 D). Films were prepared via spin coating and analysed using AFM, initially via tapping mode for topographic assessment followed by force-distance measurements which allowed assessment of site-specific adhesion. The results showed that colloidal particles were clearly observed topographically in freshly prepared samples, with coalescence detected on curing via the disappearance of discernible surface features and a decrease in roughness indices. The effects of temperature and humidity on film curing were also studied, with the former having the most pronounced effect. AFM force measurements showed that the variation in adhesive force reduced with increasing curing time, suggesting a novel method of quantifying the rate of film formation upon curing. It was concluded that the AFM methods outlined in this study may be used as a means of qualitatively and quantitatively monitoring the curing of pharmaceutical films as a function of time and other variables, thereby facilitating rational design of curing protocols.