A probabilistic approach to measure the strength of bone cell adhesion to chemically modified surfaces

Patterned surfaces with alternating regions of amino silanes [N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (EDS)] and alkyl silanes [dimethyldichlorosilane (DMS)] have been used to alter the kinetics of spatial distribution of cellsin vitro. In particular, we have previously observed the preferential spatial distribution of bone cells on the EDS regions of EDS/DMS patterned surfaces (10). In this study, we examined whether the mechanism of spatial distribution of cells on the EDS regions was adhesion mediated. Homogeneous layers of EDS and DMS were immobilized on quartz substrates and characterized by contact angle, X-ray photoelectron spectroscopy, and spectroscopic ellipsometry. The strength of bone cell attachment to the modified substrates was examined using a radial flow apparatus, within either 20 min or 2 hr of cell incubation in the presence of serum. A Weibull distribution was chosen to characterize the strength of cell-substratum adhesion. Within 20 min of cell exposure, the strength of adhesion was significantly larger on EDS and clean surfaces, compared with DMS surfaces (p<0.0001). Within 2 hr of cell incubation, there was no statistical difference between the strength of cell adhesion to EDS, DMS, and clean surfaces. The results of this study suggest that the surface chemistry mediates adhesion-based spatial cell arrangement through a layer of adsorbed serum proteins.     

软骨组织工程中力学因素的影响及应用

力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明，力学作用可以刺激细胞因子及激素的分泌，改变三维支架上培养的软骨细胞的新陈代谢，从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道，但对于其中的力学因素的影响（包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等）还没有完全认识。就以上几方面做一综述，并简单介绍生物反应器在软骨组织工程中的应用。     

胶原基真皮再生支架的微结构控制

综述了影响胶原基真皮再生支架微结构的各种因素及其控制方法。胶原基真皮支架的生物活性和修复创面的能力受到诸如除胶原外的其它主要材料 (第二组分 )、支架的孔径和孔隙率、支架厚度、生物活性因子以及交联度等多方面因素的综合影响。从材料学、生物学和医学的角度综合地应用物理、化学和生物学的手段探索各种影响因素的控制方法是组织工程皮肤研究的重点。     

骨髓基质细胞和壳聚糖/明胶共混材料生物相容性研究

目的:研究壳聚糖/明胶共混材料对离体培养的骨髓基质细胞粘附及增殖的影响,寻找骨髓基质细胞新的载体材料。方法:取2周龄幼兔的长骨采集骨髓,培养骨髓基质细胞,体外扩增1周后,种植于纯壳聚糖和壳聚糖/明胶共混材料的表面。在倒置光学显微镜、扫描电镜的辅助下,观察细胞的粘附和生长情况,种植7d后用透射电镜观察细胞功能状况,用MTT方法检测种植后2d、4d、6d、8d细胞的增殖情况。结果:壳聚糖/明胶共混材料和纯壳聚糖能促进骨髓基质细胞在材料表面粘附并保持其在机体内的形态。壳聚糖/明胶共混材料表面的骨髓基质细胞功能活跃。在材料表面和培养板表面培养的骨髓基质细胞均能持续增殖,而壳聚糖/明胶共混材料能显著促进骨髓基质细胞的增殖(P<0.01)。结论:壳聚糖/明胶共混材料保持了壳聚糖的某些生物活性,同时由于加入明胶,能促进骨髓基质细胞的增殖,可作为骨髓基质细胞的载体应用于组织工程。     

羟基磷灰石/胶原-聚乳酸三维多孔框架材料的制备成形及分析

目的：合成新型的复合生物材料框架作为骨组织工程研究的细胞外基质材料。方法：本研究采用材料学自组装技术的原理，以Ⅰ型胶原蛋白为分子模板，引导钙磷盐在液相中的矿化，制备具有天然骨基质层状结构的羟基磷灰石／胶原复合材料，并以热致分相法制备了羟基磷灰石／胶原-聚乳酸复合三维多孔框架。结果：羟基磷灰石／胶原复合材料具有与天然骨基质相似的成分与结构，加入聚乳酸制备成三维多孔框架，孔隙直径界于50um-300um。结论：羟基磷灰石／胶原-聚乳酸复合三维多孔框架可能作为骨组织工程良好的细胞外基质材料。     

关于研究生课程"生物医学工程前沿"建设的意见

"生物医学工程前沿"是国家所规定的生物医学工程专业研究生的课程之一.它以极广的知识领域,最新的学术动态,最先进的医疗技术等为主要内容,展示该专业的研究范围、前沿动态、发展趋向及未来前景,是学生们全面了解本专业的最好窗口,也是获取专业知识的最丰富园地.     

Evaluation of activities in the health services

For planning or co-ordinating health services it is necessary to have reference points for evaluating similar departments in which homogeneous or equivalent activities are carried out. It is also necessary to consider the cost/benefit of the services. The paper presents several new indices of performance which may be applied to this problem and which enable quantitative comparisons to be made between hospitals and between departments. These indices include assessment of electrical hazards and service ability of equipment as well as the ratio of technical support staff to inpatient stay. The indices have been evaluated in a few large hospitals and found to be an effective management tool.     

1978—1987年北京市十六所大学本科生因精神疾病休学、退学情况分析

本文对北京市十六所大学十年来因精神疾病休学、退学的资料进行了分析。结果表明,因精神疾病休学率有所上升,精神疾病是大学生因病休、退学的主要原因,其中以神经症为主。因精神疾病的休退学率以二、三年级学生,及理工科大学学生最高。     

含人发角蛋白和胶原的真皮类似物的研究

目的　以大鼠为动物模型 ,探讨由人发角蛋白和胶原组成的真皮类似物植入体内后真皮重建过程中的形态学变化。方法　将含人发的活性皮肤替代物植入大鼠皮下 ,于术后不同时间取出植入物及其周围组织 ,作组织学和免疫组化观察。结果　术后 4天 ,为急性炎症期 ,同时可见有约 1/2的内皮细胞以及成纤维细胞等 ;术后第 7天 ,植入物内可见大量的血管及其他迁入的细胞 ;第 3周人发开始降解 ,出现胶原纤维 ;6周后 ,人发碎裂降解 ,胶原纤维粗大 ,集结成束 ,与真皮胶原无明显区别。结论　组织学的结果显示人发可以作为真皮基质来修复皮肤缺损     

Decellularized ureter for tissue-engineered small-caliber vascular graft

Previous attempts to create small-caliber vascular prostheses have been limited. The aim of this study was to generate tissue-engineered small-diameter vascular grafts using decellularized ureters (DUs). Canine ureters were decellularized using one of four different chemical agents [Triton-X 100 (Tx), deoxycholate (DCA), trypsin, or sodium dodecyl sulfate (SDS)] and the histology, residual DNA contents, and immunogenicity of the resulting DUs were compared. The mechanical properties of the DUs were evaluated in terms of water permeability, burst strength, tensile strength, and compliance. Cultured canine endothelial cells (ECs) and myofibroblasts were seeded onto DUs and evaluated histologically. Canine carotid arteries were replaced with the EC-seeded DUs (n = 4). As controls, nonseeded DUs (n = 5) and PTFE prostheses (n = 4) were also used to replace carotid arteries. The degree of decellularization and the maintenance of the matrix were best in the Tx-treated DUs. Tx-treated and DCA-treated DUs had lower remnant DNA contents and immunogenicity than the others. The burst strength of the DUs was more than 500 mmHg and the maximum tensile strength of the DUs was not different to that of native ureters. DU compliance was similar to that of native carotid artery. The cell seeding test resulted in monolayered ECs and multilayered alpha-smooth muscle actin-positive cells on the DUs. The animal implantation model showed that the EC-seeded DUs were patent for at least 6 months after the operation, whereas the nonseeded DUs and PTFE grafts become occluded within a week. These results suggest that tissue-engineered DUs may be a potential alternative conduit for bypass surgery.