High cell density alters the ratio of type III to I collagen synthesis by fibroblasts

HUMAN fibroblasts in culture synthesise both type I and type III collagen(1), with type I accounting for 70-90% of the total(2). In culture, the rates at which these proteins are synthesised is constant and apparently rather rigidly controlled(3). However, the proportions of these collagens differs in cells cultured with increased amounts of serum (increased type III/I)(4) as well as in cells obtained from patients with certain diseases. Cells from patients with the Ehlers-Danlos type IV syndrome make little or no type III collagen(5,6), whereas cells from patients with osteogenesis imperfecta have an increased type III/I (refs 7, 8). We have found that cells from some patients with systemic sclerosis (scleroderma), have a reduced type III/I ratio. However, as previously reported, these cells grew to a lower density than control cells(9). We report here that normal fibroblasts from human and guinea pig skin produce proportionally more type III collagen at high cell density, probably because of a reduction in the synthesis of type I collagen.     

HMGB1对心肌成纤维细胞增殖和Ⅰ、Ⅲ胶原蛋白分泌的影响及意义

摘要：目的：通过观察HMGB1（ High mobility group protein-B1）对新生SD（Sprague-Dawley）大鼠心肌成纤维细胞(CFs)增殖和胶原合成的影响,探讨HMGB1在心梗后心脏重构过程中的作用。方法：以培养的新生SD（Sprague-Dawley）大鼠CFs为实验对象,分别给予0(对照组)、0.01、0.1、和1 mg/L 浓度的HMGB1进行干预,6、12、18、24和48小时后进行四氮唑盐(MTT)比色法检测CFs增殖水平,采用荧光实时定量PCR法检测Ⅰ、Ⅲ型胶原蛋白mRNA表达。结果：1.与对照组相比,48小时后,不同浓度的HMGB1组新生SD大鼠CFs增殖水平和Ⅰ、Ⅲ型胶原mRNA的表达水平均较对照组有所增高(p<0.05)。2.HMGB1浓度为0.1mg/L时CFs增殖水平和I、Ⅲ型胶原mRNA表达水平较其他处理组均升高(p<0.05)。结论：HMGB1能促进SD大鼠CFs增殖及Ⅰ、Ⅲ型胶原蛋白mRNA的表达,其作用显示在低水平时可能呈浓度依赖性,并且浓度为0.1mg/L时效应最明显,结果显示HMGB1参与了心梗后的心脏重构过程并发挥了重要作用。     

重组大肠杆菌分批-补料培养生产类人胶原蛋白的过程控制

目的优化重组大肠杆菌高密度发酵的调控工艺。方法通过考察比生长速率、3种控氧方式以及诱导强度对细胞和类人胶原蛋白产量的影响,确定最佳的发酵工艺。结果比生长速率显著影响类人胶原蛋白的产量,且最适比生长速率为0.15～0.20h-1;在提高罐压的条件下,细胞和类人胶原蛋白的浓度均显著高于其他两种控氧方式,充入富氧空气的细胞和类人胶原蛋白的浓度均最低;诱导强度对细胞生长和蛋白质表达的影响非常大,当细胞浓度达47±2g/L(DCW)时,开始升温至42℃进行诱导,最佳条件为42℃保温2～3h,然后降温至39℃继续培养5～6h。结论通过优化重组大肠杆菌分批补料培养生产类人胶原蛋白的工艺,使得细胞和类人胶原蛋白浓度分别达68.94g/L(DCW)和13.02g/L。     

大跨度连续刚构桥的施工监控

结合东江南特大桥工程实例,介绍了预应力混凝土连续刚构桥施工监控的目的、工况、仿真分析、线形和应力的控制、参数识别等。实测数据表明,大桥监控取得了良好效果。     

论语言个性的言语文明类型及其运用

归纳了具体个人的语言个性和言语文明类型，并阐述了形成言语文明类型的原因。了解各种人的语言个性和他们特有的交际手段，有助于我们言语的表达。掌握各种言语文明类型可以更好地提高我们言语文明水平和教学水平。     

Apoptosis in suspension culture of tobacco cells induced by heat shock

The induction of apoptosis in suspension culture of tobacco cells by heat shock is reported for the first time. Heat treatment (48℃ for 4 h) of tobacco cells led to the appearance of typical hallmarks of apoptosis. It was demonstrated by DNA laddering analysis that the cells treated with heat shock at 48℃ for 4 h had a serious degradation of nuclear DNA into multi-nu-cleosomal sizes, suggesting that heat shock activated endogenous nuclease which led to DNA cleavage at the linkage sites between the nucleosomes, but ladders were very faint for DNA from 2 and 9 h heat-treated cells. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL) detection also showed that most of these treated cells (48℃ for 4 h) displayed positive reactions, indicating a serious DNA 3'-OH cleavage in their nuclei. Moreover, some other cytological changes in apoptotic cells, such as cell shrinkage, chromatin aggregation, nucleus collapse, have also been observed by 4', 6'-diamidino-2-phenyl-indole (DAPI) staining.