Optimization of 3-D hepatocyte culture by controlling the physical and chemical properties of the extra-cellular matrices

Hepatocytes are anchorage-dependent cells sensitive to microenvironment; the control of the physicochemical properties of the extra-cellular matrices may be useful to the maintenance of hepatocyte functions in vitro for various applications. In a microcapsule-based 3-D hepatocyte culture microenvironment, we could control the physical properties of the collagen nano-fibres by fine-tuning the complex-coacervation reaction between methylated collagen and terpolymer of hydroxylethyl methacrylate-methyl methacrylate-methylacrylic acid. The physical properties of the nano-fibres were quantitatively characterized using back-scattering confocal microscopy to help optimize the physical support for hepatocyte functions. We further enhanced the chemical properties of the collagen nano-fibres by incorporating galactose onto collagen, which can specifically interact with the asialoglycoprotein receptor on hepatocytes. By correlating a range of collagen nano-fibres of different physicochemical properties with hepatocyte functions, we have identified a specific combination of methylated and galactosylated collagen nano-fibres optimal for maintaining hepatocyte functions in vitro. A model of how the physical and chemical supports interplay to maintain hepatocyte functions is discussed.     

骨折愈合塑形的力学机理I^＊——骨表面再造理论的应用

深入探讨长骨骨折愈合塑形阶段的力学机理,采用骨表面再造理论与有限元结合的方法。我们选取用应变能密度作为力学激励的骨表面再造理论,有限元分析采用三维的空间模型,利用我们编制的长骨表面再造系统“BRSS97”对长骨骨折愈合塑形阶段的三种类型：外骨痂型、骨内缺损型和骨外缺损型的力学机理进行研究。结果表明：骨痂可以完全吸收,骨缺损可以恢复,三种情况下骨均可以恢复到正常状态。由此说明长骨骨折愈合塑形过程就是骨材料对力学激励的适应过程。     

Galectin-1 and galectin-3 in chronic pancreatitis

Galectin-1 and galectin-3 have important functions in cell-cell interactions, cell adhesion to extracellular matrix, the organization of extracellular matrix, and tissue remodeling. To assess their potential role in chronic pancreatitis (CP), we examined their expression by Northern blot analysis, in situ hybridization, immunohistochemistry, and Western blot analysis in normal and CP pancreatic tissues. Northern blot analysis revealed a 4.5-fold increase of galectin-1 mRNA (p < 0.01) and a 3.8-fold increase of galectin-3 mRNA (p < 0.01) in CP samples compared with normal controls. In situ hybridization analysis of normal pancreas indicated low abundance of galectin-1 mRNA in fibroblasts, whereas galectin-3 mRNA was moderately present in ductal cells. CP samples exhibited moderate to intense galectin-1 mRNA signals in fibroblasts, whereas galectin-3 mRNA signals were intense in the cells of ductular complexes and weak in the degenerating acinar cells. In addition, intense galectin-1 and galectin-3 mRNA signals were present in nerves of normal and CP samples. Immunohistochemistry showed a distribution pattern of galectin-1 and galectin-3 similar to that described for in situ hybridization. Relative quantification of galectin-1 and galectin-3 protein by immunoblotting revealed an increase of 3.2-fold and 3.0-fold, respectively, in CP compared with normal controls. There was a significant correlation between galectin-1 and fibrosis and between galectin-3 and fibrosis and the density of ductular complexes. Up-regulation of galectin-1 in fibroblasts and galectin-3 in ductular complexes suggests a role of these lectins in tissue remodeling in CP. Galectin-1 might participate in ECM changes, whereas galectin-3 seems to be involved in both ECM changes and ductular complex formation.     

Molecular and genetic characterizations of five pathogenic and two non-pathogenic monoclonal antiphospholipid antibodies

Antiphospholipid syndrome (APS) is an autoimmune disease that is characterized by thrombosis, recurrent fetal loss and thrombocytopenia. Antiphospholipid antibodies, detected by enzyme-linked immunoabsorbent assays (aCL) and/or in vitro blood clotting assays (LAC) are strongly associated with APS. Both the molecular structures used by pathogenic antiphospholipid antibodies and the genetic mechanisms leading to their production are unknown. We describe here the variable region genes of seven IgG antiphospholipid antibodies derived from two APS patients. Of these, five are pathogenic as defined in a mouse model of thrombosis and two are not. Analyses of the expressed variable region genes show no preferential V gene usage. However, similar to anti-DNA antibodies, pathogenic antiphospholipid antibodies contain an increased number of arginine residues in the third complimentarity-determining region (CDR3) of their H chains. The increased accumulation of arginine residues in the V(H) CDR3 may act to enhance antigen binding, promote disease and point to the importance of the H chain in the pathogenic potential of certain antiphospholipid antibodies.     

Biochemical and biophysical analysis of heptad repeat regions from the fusion protein of Menangle virus,a newly emergent paramyxovirus

E. coli in vitro expression system. The GST-removed purified 2-Helix protein could form a stable trimer in vitro judging by gel-filtration and chemical cross-linking. CD spectra showed that the 2-Helix protein had a high percentage of α-helix and was very thermo-stable. Crystals of the 2-Helix protein preparations have been obtained in many conditions with hanging-drop diffusion method. These results indicated that Menangle virus has the common features of the fusion protein for other paramyxoviruses and should adopt a similar fusion mechanism to other members. As the HR regions of Menangle virus F protein could form stable six-helix bundle coiled coil structure, they should be used as drug target for the design of fusion inhibitors, as successfully used for other parmyxoviruses. This is especially relevant to such a newly emergent virus with zoonotic potentials. Received January 23, 2003; accepted February 28, 2003 Published online April 28, 2003     

用小波变换提取视觉诱发电位信号

视觉诱发电位（ＶＥＰ）信号的动态提取及处理具有重要的临床意义。通过硬件采集的ＶＥＰ信号经过叠加平均处理后仍含有大量背景噪声，不能直接用于诊断分析。小波变换是一种新兴时频分析方法，适于分析非平稳信号。在我们研制的视觉生理地形图系统中，成功地用它从背景噪声中提取出ＶＥＰ信号，完成信号的预处理。     

5一羟色胺能神经对横断损伤脊髓的再支配-脊髓内移植研究

用成年SD大鼠20只在脊髓的低位胸髓完全横断损伤,分别在1周和1月后,用富含5一羟色胺(5—HT)神经元的胚鼠脑干中缝组织悬液植人损伤尾侧的脊髓内,动物存活2个月,脊髓作5—HT免疫组化观察.结果:(1)胚5-HT能神经元能在成年大鼠脊髓内存活,5-HT纤维大多在灰质中延伸并向靶区分布,(2)损伤后1周移植组的5-HT能神经元存活量,5-HT纤维在宿主脊髓内延伸距离,以及5-HT末梢再分布的密度都优于损伤后1月移植组.     

异种骨内固定器力学性能的实验研究

目的了解牛骨材料及其构件的力学强度[抗拉、抗压、抗折(弯曲)和抗扭(剪切)强度].方法将材料分为天然、处理和构件(即产品)三组并制成标准试件,用规定设备按标准方法进行检测.结果(1)牦牛股骨拉伸、压缩、抗折、扭转极限应力分别为106.35±3.45、127.60±2.65、225.9±4.1、53.45±1.55(MPa),胫骨拉伸、压缩、抗折、扭转极限应力分别为114.96±1.46、184.75±3.25、211.35±2.45、51.9±0.5(MPa).湖区水牛胫骨拉伸、压缩、抗折、扭转极限应力分别为1 28.1±11、195.8±9.4、167.4±1 2.7、54.25±0.75(MPa).(2)E0气薰灭菌对牛骨材料的力学性能无明显影响,幅照灭菌对牛骨材料的力学性能稍有影响.(3)处理后,牛骨螺钉、圆钉的抗折强度较材料有所降低,而抗拉强度、抗压强度、抗扭强度变化不大.结论牛骨是一种力学性能良好,适合制作内固定构件的高强度生物材料.     

单克隆抗体2A7亲和层析法纯化红细胞膜表面的CD59分子

用抗ＣＤ５９单抗２Ａ７与ＣＮＢｒ－Ｓｅｐｈａｒｏｓｅ４Ｂ偶联制备亲和层析柱，从正常人红细胞膜蛋白抽提物中分离纯化出ＣＤ５９分子。本法纯化的ＣＤ５９分子量为１８－２０ＫＤａ对还原剂敏感，与ＭｃＡｂｓｓＭＥＭ４３和１Ｆ５有高亲和性，再掺入豚鼠红细胞后，能够抑制人体补体的反应性溶血，本文还对三株抗ＣＤ５９单抗２Ａ７，ＭＥＭ４３及１Ｆ５的抗原特异性进行了初步分析。