It is known that dentin sialophosphoprotein (DSPP) is processed into NH2- and COOH-terminal fragments, but its key cleavage site has not been identified, nor has its full-length form been discovered. The objectives of this study were to identify the key cleavage site during DSPP processing and to search for full-length DSPP in vivo. We generated a construct encoding DSPP, in which Asp452, a cleavage site residue, was replaced by Ala452. The pulp-odontoblast complex and dentin were extracted, chromatographically separated, and assessed by Stains-All staining, Western immunoblotting, and mass spectrometry. These studies showed that the substitution of Asp452 by Ala452 completely blocks the cleavage of mouse DSPP in the transfected cells, indicating that the NH2-terminal peptide bond of Asp452 is essential for the initiation of DSPP proteolytic processing. The results of this study revealed the presence of full-length DSPP and its processed fragments in extracts from the pulp/odontoblast and dentin.

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M icroelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) technologies enable us to create varioius useful sensing and actuating devices integrated with other microelectronic, optoelectronic, microwave, thermal and mechanical devices for advanced microsystems. One of the critical issues for cost-effective integration is MEMS/NEMS packaging, which is often neglected and therefore blocks potential products from a successful market launch. This special issue has a collection of 16 papers covering different challenging aspects in MEMS/NEMS packaging. It begins with an introduction to MEMS/NEMS packaging, followed by wafer-level MEMS packaging and self-assembly for nano-devices. These three papers will help readers understand the field with representative applications and packaging technologies. The next five papers will present studies on MEMS packaging for different applications: bioMEMS, RF MEMS, optical MEMS and MEMS for fluid mixing. The second group of papers will address specific design or technology issues in details. In this group, the first five papers study the use of getters, laser-assisted sealing, glass-to-glass wafer bonding, improved corrosion resistance, and through-wafer vias. The last three papers present thermal and mechanical designs for

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