Robust fluidic connections to freestanding microfluidic hydrogels

Biomimetic scaffolds approaching physiological scale, whose size and large cellular load far exceed the limits of diffusion, require incorporation of a fluidic means to achieve adequate nutrient/metabolite exchange. This need has driven the extension of microfluidic technologies into the area of biomaterials. While construction of perfusable scaffolds is essentially a problem of microfluidic device fabrication, functional implementation of free-standing, thick-tissue constructs depends upon successful integration of external pumping mechanisms through optimized connective assemblies. However, a critical analysis to identify optimal materials/assembly components for hydrogel substrates has received little focus to date. This investigation addresses this issue directly by evaluating the efficacy of a range of adhesive and mechanical fluidic connection methods to gelatin hydrogel constructs based upon both mechanical property analysis and cell compatibility. Results identify a novel bioadhesive, comprised of two enzymatically modified gelatin compounds, for connecting tubing to hydrogel constructs that is both structurally robust and non-cytotoxic. Furthermore, outcomes from this study provide clear evidence that fluidic interconnect success varies with substrate composition (specifically hydrogel versus polydimethylsiloxane), highlighting not only the importance of selecting the appropriately tailored components for fluidic hydrogel systems but also that of encouraging ongoing, targeted exploration of this issue. The optimization of such interconnect systems will ultimately promote exciting scientific and therapeutic developments provided by microfluidic, cell-laden scaffolds.     

Cell chip array for microfluidic proteomics enabling rapid in situ assessment of intracellular protein phosphorylation

We discuss the ability to perform fluorescent immunocytochemistry, following cell fixation, using a microfluidic array of primary, nonadherent, single CD34+ stem cells. The technique requires small cell samples and proceeds with no cell loss, making it well-suited to monitoring these rare patient-derived cells. The chip allows us to correlate live cell dynamics across arrays of individual cells with post-translational modifications of intracellular proteins, following their exposure to drug treatments. Results also show that due to the microfluidic environment, the time scale of cell fixation was significantly reduced compared to conventional methods, leading to greater confidence in the status of the protein modifications studied.     

减少和抑制核HDAC5对骨骼肌细胞GLUT4基因表达的影响

验证收缩骨骼肌细胞葡萄糖转运蛋白4（GLUT4）基因的表达在转录水平上是否受转录抑制子Ⅱ型HDAC5蛋白（简写为HDAC5）的调节。研究运用运动模拟信号5-氨基-4-甲酰胺咪唑核糖核苷酸（AICAR）和HDACs抑制剂SCRIPTAID孵育骨骼肌细胞。用蛋白印迹技术测定HDAC5蛋白表达,定量RT-PCR法检测GLUT4 mRNA表达。与无AICAR的对照组相比,AICAR组骨骼肌细胞内HDAC5减少了29%,并伴随有124% GLUT4 mRNA的增加,但肌细胞内HDAC5的蛋白总量无变化;使用HDACs抑制剂SCRIPTAID刺激骨骼肌细胞能够明显增加核心组蛋白乙酰化水平和上调GLUT4基因的表达。这些结果提示,通过AICAR和SCRIPTAID分别减少或抑制核HDAC5均能上调骨骼肌细胞GLUT4基因的转录,HDAC5可能在转录水平上对肌肉收缩引起的GLUT4基因的表达起着重要的调节作用。     

When culture and the law clash: A primer on the extraterritorial implications of U.S. anti-discrimination rules and regulations

The rapid globalization of U.S. business has generated many questions about the extraterritorial implications of U.S. anti-discrimination rules and regulations. This paper provides an introduction to the relevant statutes and related case law that govern the extraterritorial responsibilities of U.S. companies with interests in foreign firms. Particular attention is paid to the extraterritorial requirements of the Civil Rights Act of 1964, including important amendments to the Act added when Congress passed the Civil Rights Act of 1991. This paper also describes the defenses U.S. firms can use to insulate themselves from the extraterritorial requirements of these rules and regulations as well as issues and problems created when the cultural norms and customs of foreign countries clash with U.S. law. Suggestions are then made about how U.S. firms can meaningfully comply with the extraterritorial requirements of U.S. anti-discrimination rules and regulations. Finally, the paper examines legal and organizational issues that require further clarification and interpretation.