Isolation of human epidermal stem cells by adherence and the reconstruction of skin equivalents

The isolation of human epidermal stem cells is critical for their clinical applications. In the present study, we isolated three populations of epidermal keratinocytes according to their ability to adhere to collagen type IV: i.e., rapidly adhering (RA), slowly adhering (SA), and non-adhering (NA) cells. The aim of this study was to characterize RA cells and to investigate the possibility of using these cells for epidermis reconstruction. To identify RA cells, flow cytometric analysis was performed using anti-₆ integrin and anti-CD71 antibodies. RA cells express high levels of ₆ integrin and low levels of CD71, which are considered as markers of an epidermal stem cell nature. Furthermore, electron microscopy showed that RA cells are small and have a high nuclear to cytoplasmic ratio, whereas SA and NA cells have well-developed cellular organelles and abundant tonofilaments. Western blot analysis showed that RA cells are slow cycling and express p63, a putative epidermal stem cell marker, whereas SA and NA cells express c-Myc, which is known to regulate stem cell fate. To compare epidermal regenerative abilities, skin equivalents (SEs) were made using RA, SA, and NA cells. The epidermis constructed from RA cells was well formed compared to those formed from SA or NA cells. In addition, only SEs with RA cells expressed ₆ integrin and ₁ integrin at the basal layer. These results indicate that RA cells represent epidermal stem cells and are predominately comprised of stem cells. Therefore, the isolation of RA cells using a simple technique offers a potential route to their clinical application, because they are easily isolated and provide a high yield of epidermal stem cells.Received 2 July 2004; received after revision 20 August 2004; accepted 10 September 2004     

Profiling of the secreted proteins during 3T3-L1 adipocyte differentiation leads to the identification of novel adipokines

Adipose tissue is an endocrine organ capable of secreting a number of adipokines with a role in the regulation of adipose tissue and whole-body metabolism. We used two-dimensional gel electrophoresis combined with mass spectrometry to profile the secreted proteins from (pre)adipocytes. The culture medium of 3T3-L1 cells during adipocyte differentiation was screened, and 41 proteins that responded to blocking of secretion by 20°C treatment and/or brefeldin A treatment were identified. Prohibitin, stress-70 protein, and adhesion-regulating molecule 1 are reported for the first time as secreted proteins. In addition, procollagen C-proteinase enhancer protein, galectin-1, cyclophilin A and C, and SF20/IL-25 are newly identified as adipocyte secreted factors. Secretion profiles indicated a dynamic environment including an actively remodeling extracellular matrix and several factors involved in growth regulation.Received 15 June 2004; received after revision 26 July 2004; accepted 2 August 2004     

Apoptotic cell death in the lactating mammary gland is enhanced by a folding variant of α-lactalbumin

Apoptosis is essential to eliminate secretory epithelial cells during the involution of the mammary gland. The environmental regulation of this process is however, poorly understood. This study tested the effect of HAMLET (human -lactalbumin made lethal to tumor cells) on mammary cells. Plastic pellets containing HAMLET were implanted into the fourth inguinal mammary gland of lactating mice for 3 days. Exposure of mammary tissue to HAMLET resulted in morphological changes typical for apoptosis and in a stimulation of caspase-3 activity in alveolar epithelial cells near the HAMLET pellets but not more distant to the pellet or in contralateral glands. The effect was specific for HAMLET and no effects were observed when mammary glands were exposed to native a-lactalbumin or fatty acid alone. HAMLET also induced cell death in vitro in a mouse mammary epithelial cell line. The results suggest that HAMLET can mediate apoptotic cell death in mammary gland tissue.Received 30 January 2004; received after revision 5 March 2004; accepted 16 March 2004     

团簇Y_3O,Y_3Oˉ和Y_3O~+的几何和电子结构

采用密度泛函理论(DFT)中的B3LYP方法,在LANL2DZ基组下,对团簇Y3O、Y3O-、Y3O+的几何结构进行优化。结果表明,Y3O团簇的平衡构型都是四面体结构,具有CS对称性。Y3O的基态是两重态2A′,Y3O-的基态是三重态3A′′,Y3O+的基态是单一态1A′。计算得到的电子亲和能和电离能都与实验吻合。电荷分布和自旋密度分析表明团簇Y3O的性质主要取决于"碎块"Y3。     

“3＋X”高考模式下“X”的教学思考

“3＋2”的高考模式已完成历史使命,“3＋X”的模式将在2002年全国大多数省、市推行。为了适应新的高考模式,我们很有必要认真研究全国“3＋X”科综合试卷,从中得到一些启迪,以利于搞好今后的综合学科教学。     

优化设计中的拟网格原理（I）

在研究目标函数和约束条件的性质与允许误差的条件下,研究了断定全局优化方案就存在于变量网格结点中的若干个结点之间的问题.提出了拟三维空间和超球体概念;导出了确定可计算的网格结点公式,证明了持定点的覆盖定理。     

应用Delphi4的MIDAS构件组开发起重机零部件管理系统

Delphi自版本4就开始提供一组新的构件MIDAS,使用它,可以方便地开发具有三层体系结构的数据库应用程序。本文分析了MIDAS构件组的开发原理,并以起重机为例,论述了开发基于三层结构的起重机零部件管理系统的基本步骤,并详细讨论了开发中三层结构的实现过程。     

“雅”译观的历史与现实

本文探讨了严氏“雅”译观产生的历史、社会、教育背景和哲学基础。从辩证历史观的角度看 ,“雅”译观作为译事中宏观的指导理论和译文评鉴标准 ,与西学的“等值论”相得益彰 ,仍不失具有重要的现实意义和指导作用