Fabrication of high quality plan-view TEM specimens using the focused ion beam

We describe a technique using a focused ion beam instrument to fabricate high quality plan-view specimens for transmission electron microscopy studies. The technique is simple, site-specific and is capable of fabricating multiple large, >100 μm2 electron transparent windows within epitaxially-grown thin films. A film of La0.67Sr0.33MnO3 is used to demonstrate the technique and its structural and functional properties are surveyed by high resolution imaging, electron spectroscopy, atomic force microscopy and Lorentz electron microscopy. The window is demonstrated to have good thickness uniformity and a low defect density that does not impair the film’s Curie temperature. The technique will enable the study of in–plane structural and functional properties of a variety of epitaxial thin film systems

Functional expression of chemokine receptor CXCR4 on human epithelial cells

Chemokines and their receptors play an important role in the process of leucocyte recruitment at sites of inflammation. However, recent evidence suggests that these proteins can also regulate non-leucocyte cell functions such as angiogenesis, migration and proliferation. We have investigated the expression of the CXC chemokine receptor 4 (CXCR4) on primary cultures of type II alveolar epithelial cells, their transformed counterpart, the A549 cell line and also on other epithelial cell lines from various tissues. We found that all epithelial cell types tested express mRNA for CXCR4. Flow cytometric analysis and immunocytochemical staining shows that CXCR4 chemokine receptor is abundantly expressed on the surface of A549 epithelial cells. Furthermore, A549 cells responded to the CXCR4 ligand, stromal-derived factor-1α (SDF-1α) with a rapid and robust calcium mobilization and not to other CXC chemokines, suggesting that CXCR4 is functionally active and is able to couple to G-protein signalling mechanisms. A549 cells did not proliferate in response to either SDF-1α or interleukin-8 (IL-8) CXC chemokines. These findings may have important implications for epithelial physiology and pathology