三维超声用于青少年特发性脊柱侧凸评估的信度与效度研究

目的:探索三维超声成像技术在临床上评估和测量青少年特发性脊柱侧凸(AIS)患者椎体侧凸角度的可行性;通过与磁共振成像(MRI)的测量方法比较,评价三维超声测量结果的信度与效度。方法:16例AIS女性患者在同一上午进行三维超声和MRI的全脊柱扫描。将三维超声和MRI的图像进行随机分配,两位评测者随机抽取图像进行测量;所有图像均需进行3次测量,每次测量间隔1周,且测量过程中对两位评测者采取盲法。在冠状面上,三维超声成像采用椎板中心法(COL)测量AIS的椎体侧凸角度;而MRI成像采用Cobb方法。通过计算组内相关系数(ICC[2,k])评价三维超声测量方法的信度;通过与MRI测量结果比较,采用配对t检验及Pearson相关系数,评价三维超声测量方法的效度。结果:在冠状面上,三维超声成像COL测量方法评估AIS患者椎体侧凸角度具有较高的评测者内和评测者间信度(ICC[2,K]0.9,P0.05)。三维超声成像COL测量方法和MRI成像Cobb测量方法评估AIS椎体侧凸角度的结果之间没有显著性差异(P0.05);两种测量方法具有较高的相关性(r0.9)。结论:三维超声成像技术可用于评估AIS患者椎体在冠状面上的侧凸角度,具有较高的信度和效度。     

Elastocapillary interactions on nematic films

Rod-like colloids distort fluid interfaces and interact by capillarity. We explore this interaction at the free surface of aligned nematic liquid crystal films. Naive comparison of capillary and elastic energies suggests that particle assembly would be determined solely by surface tension. Here, we demonstrate that, under certain circumstances, the capillary and elastic effects are complementary and each plays an important role. Particles assemble end-to-end, as dictated by capillarity, and align along the easy axis of the director field, as dictated by elasticity. On curved fluid interfaces, however, curvature capillary energies can overcome the elastic orientations and drive particle migration along curvature gradients. Domains of dominant interaction and their transition are investigated.Whereas directed assembly of colloids to form organized structures is often guided by external applied fields (1–3), recent advances instead rely on interactions that emerge when particles are placed in a soft material. Two important examples are elastic interactions between particles in liquid crystals (LCs) (4–9) and capillary interactions between particles at fluid interfaces (10–13). Well-defined director fields with associated elastic energy landscapes can be imposed by confining nematic LCs between surfaces that favor given molecular orientations. When particles are introduced, they elicit an elastic response that moves them to preferred locations or drives them to interact with each other (14–17). Capillary interactions occur between particles trapped at fluid interfaces; the particles distort the interface and assemble to minimize the interfacial area (10, 18, 19). Interface curvature fields can steer particles along well-defined paths and orient them via curvature capillary energies. Because both fluid interfaces and LC director fields are readily reconfigured, a deeper understanding of these mechanisms paves the way for responsive or reconfigurable materials. Can capillarity and elasticity together direct interactions between colloids on free surfaces of nematic films? To our knowledge, thus far only spherical colloids have been studied at nematic interfaces; for such particles, capillary interactions are typically weak (9). Anisotropic particles, however, create larger interface deformations with associated significant capillary interactions, as has been established in studies on isotropic fluids with planar (12, 20) and curved (21) interfaces.An a priori comparison of capillarity to elastic interactions suggests that capillarity would dominate, and elasticity would not play an important role. For example, a particle of radius R ～ 10^?5 m on a nematic LC of average elastic constant K ～ 10^?11 N with surface tension γ ～ 10^?2 Nm^–1 has an elasto-capillary number γR/K ～ 10³ ? 10⁴, indicating that capillary effects are far larger than those of elastic origin. However, a more careful scrutiny of the magnitude of these interactions for, for example, cylindrical microparticles on nematic films indicates otherwise. When immersed in an oriented hybrid nematic film, cylindrical microparticles of length L and radius R chain by elastic dipolar interactions and orient along the director field, with elastic energies and torques  ～ KL (22, 23). On fluid interfaces, such microparticles distort fluid interfaces with characteristic deformation magnitudes H_p ? R and associated capillary energy ∼γHp2. For this situation, the ratio of capillary to elastic energies is far smaller, indicating that there may be a more interesting interplay of these effects. We probe this interplay in a study of cylindrical microparticles with homeotropic anchoring at free surfaces of an aligned hybrid nematic film, a system in which elastic effects and capillary effects can play complementary or competing roles.     

Architecture and migration of an epithelium on a cylindrical wire

In a wide range of epithelial tissues such as kidney tubules or breast acini, cells organize into bidimensional monolayers experiencing an out-of-plane curvature. Cancer cells can also migrate collectively from epithelial tumors by wrapping around vessels or muscle fibers. However, in vitro experiments dealing with epithelia are mostly performed on flat substrates, neglecting this out-of-plane component. In this paper, we study the development and migration of epithelial tissues on glass wires of well-defined radii varying from less than 1 µm up to 85 µm. To uncouple the effect of out-of-plane curvature from the lateral confinement experienced by the cells in these geometries, we compare our results to experiments performed on narrow adhesive tracks. Because of lateral confinement, the velocity of collective migration increases for radii smaller than typically 20 µm. The monolayer dynamics is then controlled by front-edge protrusions. Conversely, high curvature is identified as the inducer of frequent cell detachments at the front edge, a phenotype reminiscent of the Epithelial−Mesenchymal Transition. High curvature also induces a circumferential alignment of the actin cytoskeleton, stabilized by multiple focal adhesions. This organization of the cytoskeleton is reminiscent of in vivo situations such as the development of the trachea of the Drosophila embryo. Finally, submicron radii halt the monolayer, which then reconfigures into hollow cysts.In the last years, the physical microenvironment has been repeatedly demonstrated to be crucial in defining cellular behaviors and phenotypes. For example, the rigidity of a substrate on which a cell adheres can dictate its morphology, phenotype, and even fate (1, 2). Also, the substrate’s microtopography or nanotopography can change cell adhesion and orientation (3, 4). Few studies, however, have focused on quantifying the role of out-of-plane curvature on cells or cell assemblies. This is surprising because epithelial sheets are often naturally curved, organizing into tubes, cysts, crypts, or vili whose radius of curvature is typically on the order of a few cells or tens of microns (5). Tubules can even be formed out of a cohesive chain of single cells, each enclosing a central lumen (6), as has been observed for the Drosophila trachea tip cells (7) and in some parts of the Caenorhabditis elegans digestive tract (8).In vitro, curved substrates provide a controlled way to study the role of an out-of-plane curvature on a system otherwise identical to the classic 2D culture assay on flat substrates. Because multicellular assemblies are largely controlled by the interactions between cells, the influence of curvature on epithelial tissues must be explored on monolayers. In that case, most of the reported experiments have been performed in negative curvature conditions (i.e., tubes or channels) under perfusion (9, 10). In contrast, experiments on positively curved substrates (i.e., wires) have been mostly conducted on single cells. In particular, Schwann cells (11) or fibroblasts (12–15) seeded on glass wires of radii of the order of 10 µm have been shown to align with the wire long axis. More recently, it has been observed that the response of cells to positive curvature depends strongly on the cell type: Epithelial single cells spread in all directions and favor a circumferential alignment of their actin cytoskeleton (16), while fibroblasts align their cell body and their actin fibers longitudinally (16, 17). Some of these differences are captured by a theoretical model in which cell adhesion and active contractility balance the anisotropic bending stiffness of the stress fibers (18). Very recently, monolayers formed from different endothelial cell types cultured on wires were shown to exhibit cell type-dependent orientations (19).Since growing monolayers on cylindrical wires intrinsically induces a lateral, although borderless, confinement, it is possible that confinement rather than curvature dictates the behavior of these epithelia. To uncouple these two contributions, we grew cells on smooth cylindrical rods of varying radii and systematically compared our results with experiments conducted on confining tracks of equivalent confinement. We note that, here, the basal side of the cell faces the wire and is inside the tube. The cells therefore have an inverted polarity compared with tubule formation during development. Conversely, the in vivo situation of collective migration on blood vessels, nerves, or myofibers (20–22), in particular originating from tumors, is directly comparable to our experiments.We show that below a radius of the order of 40 µm, the curvature imposes a transverse actin alignment. This cell architecture is coupled with an increase in the number of focal adhesions (FAs) and with a curvature-induced breaking off of the cells at the front edge. In contrast, confinement rather than curvature controls the dynamics of collective migration. Moreover, we show that there exists a critical submicrometric radius under which cells are unable to migrate collectively, resulting in the formation of hollow cysts.     

有限长节段融合固定治疗退变性下腰段侧凸的临床研究

目的：探讨有限长节段融合固定治疗无严重胸腰段后凸的退变性下腰段侧凸的可行性。方法回顾研究2003年6月至2012年9月,于我院接受脊柱手术的退变性下腰段侧凸患者36例,男10例,女26例,平均年龄59.7(55～73)岁。侧凸顶点 L3～4,端椎为 L2或 L3,T10～L2后凸角＜20°,其中有限长节段融合固定组(上端椎 L2)16例,长节段融合固定组(上端椎 T9～11)20例,对比两组术前及末次随访的影像学参数及 Oswestry 功能障碍评分。结果有限长节段固定组与长节段固定组比较,腰椎弯曲 Cobb’s 角、腰椎前凸角、骨盆倾斜角、骶骨倾斜角、T10～L2后凸角、近端交界性后凸角及 Oswestry 功能障碍评分等指标术前及末次随访,差异无统计学意义(P＞0.05);有限长节段融合固定组未发生术后近端交界性后凸。结论有限长节段融合固定可用于治疗无严重胸腰段后凸的退变性下腰段侧凸。     

中度曲率性近视与轴性近视的高阶像差比较研究

目的：针对不同类型中度近视眼高阶像差的分析,探讨中度近视眼中曲率性近视与轴性近视高阶像差的差异。方法：采用前瞻性研究,选取单纯性中度近视眼患者39例56眼,将其分为两组：A组为中度曲率性近视眼组（11例/16眼）,平均年龄22±2岁,平均眼轴长度23.89±0.13mm,平均角膜曲率45.56±0.95D,平均屈光度4.58±0.82D;B组为轴性近视眼组共28例40眼,平均年龄22±3岁,平均眼轴长度25.82±0.44mm,平均角膜曲率41.93±0.85D,平均屈光度4.50±0.78D。利用波前像差仪获取入选患眼瞳孔分别为4,5,6mm时高阶像差值,进行分组比较。结果：A,B两组平均年龄与平均屈光度比较,差异无显著性（P〉0.05）;两组平均角膜曲率与平均眼轴长比较,差异有显著性（P〈0.05）。A组与B组在瞳孔为6mm时RMS3,RMS4,RMS6,RMSh,C12值比较,A组/B组分别为：0.165±0.064/0.098±0.045,0.127±0.034/0.059±0.025,0.040±0.014/0.028±0.010,0.218±0.059/0.129±0.040,0.137±0.057/0.048±0.037,差异有显著性（P〈0.05）。其余不同直径瞳孔下的高阶像差各值比较,前者均高于后者,差异均有显著性（P〈0.05）。结论：在正常及中度散大瞳孔下,中度近视眼中曲率性近视的彗差、球差、次级球差及总高阶像差均较轴性近视眼为大。     

不同仪器测量角膜直径和角膜曲率的一致性评价

目的比较验光曲率仪、OrbscanⅡz眼前节分析系统和光学相干生物测量仪IOLMaster测量角膜直径和角膜曲率的差异,并评价三种测量结果的一致性。方法对70例(140眼)屈光不正患者,采用三种仪器分别测量双眼角膜水平直径和角膜前表面曲率,对这些参数进行统计学分析,应用Bland-Altman分析对三种测量结果进行一致性评价。结果验光曲率仪和OrbscanⅡz测得的角膜直径分别为(11.51±0.32)mm和(11.52±0.33)mm,差异无统计学意义(P>0.05),一致性较好;IOLMaster测得值为(12.10±0.34)mm,与另外两种仪器所测结果比较差异均有统计学意义(均为P<0.05),一致性较差。三种仪器测得的平均角膜曲率分别为(43.46±1.32)D、(43.36±1.32)D和(43.65±1.35)D,差异均无统计学意义(均为P>0.05),一致性较好。结论三种仪器在临床应用中,验光曲率仪和OrbscanⅡz测得的角膜直径值可相互替代使用,而IOLMaster测得的角膜直径偏大,不宜作为大小角膜的诊断依据。三者测得的角膜曲率值可相互替代使用,但各有优缺点,临床应互相参照、比较,确保眼球生物学参数的可靠性。     

椎动脉优势与基底动脉弯曲的关系及其对脑梗死发生率的影响

目的探讨椎动脉优势与基底动脉弯曲的关系对两者连接处脑梗死发生的影响。方法选取在我院神经内科住院治疗符合本研究纳入标准的109例急性脑梗死患者。对患者的影像学资料、梗死灶情况、椎动脉优势以及基底动脉弯曲等情况进行分析。结果92．66％（101／109）的患者表现为一侧椎动脉直径大于另一侧。68．81％（75／109）的患者椎动脉优势位于左侧。74．31％（81／109）的患者有基底动脉弯曲。随着椎动脉直径差异级别的增高,患高血压痛、中重度基底动脉弯曲的比例显著增高,且右侧椎动脉直径显著减小（P〈0．05）。3级椎动脉直径差异的患者大多有高血压病（88．89％）以及中重度基底动脉弯曲（75．00％）。单因素分析显示,老年、患有高血压病以及椎动脉直径差异是中重度基底动脉弯曲的相关因素;多因素Logistic回归分析显示,椎动脉直径差异为中重度基底动脉弯曲的独立危险因素。结论中重度基底动脉弯曲的独立危险因素是椎动脉直径差异,两者的存在促进了相应部位脑梗死的发生。