The receptor for advanced glycation end products (RAGE) is a multiligand cell surface receptor, and amyloid beta peptide (Abeta) is one of the ligands for RAGE. Because RAGE is a transporter of Abeta from the blood to the brain, RAGE is believed to play an important role in Alzheimer's disease (AD) pathogenesis. In the present study, the role of RAGE in Abeta production was examined in the brain tissue of an AD animal model, Tg2576 mice, as well as cultured cells. Because beta-site APP-cleaving enzyme 1 (BACE1), an essential protease for Abeta production, is up-regulated in cells overexpressing RAGE and in RAGE-injected brains of Tg2576 mice, the molecular mechanisms underlying RAGE, BACE1 expression, and Abeta production were examined. Because RAGE stimulates intracellular calcium, nuclear factor of activated T-cells 1 (NFAT1) was examined. NFAT1 was activated following RAGE-induced BACE1 expression followed by Abeta generation. Injection of soluble RAGE (sRAGE), which acts as a competitor with full-length RAGE (fRAGE), into aged Tg2576 mouse brains reduced the levels of plaques, Abeta, BACE1, and the active form of NFAT1 compared with fRAGE-injected Tg2576 mice. Taken together, RAGE stimulates functional BACE1 expression through NFAT1 activation, resulting in more Abeta production and deposition in the brain.
Ferroelectric Bi4Ti3O12 thin films have been grown on MgO (100) and MgO(110) substrates by the pulsed laser deposition. X-ray diffraction studies show that the films on both substrates have preferential crystallographic orientation such that most of their c axes are close to the substrate normal direction. The film on MgO(110) shows quadratic and hysteretic electro-optic characteristics with the effective coefficient of about 3.8×10−15 m2/V2.
Bi4Ti3O12 thin films have been grown on indium tin oxide coated glass by pulsed laser deposition. The films are rapidly thermal annealed at 650 °C in various kinds of ambients. X-ray diffraction and scanning electron microscopy are used to investigate crystallization and microstructures, respectively. Using Auger electron microscopy, chemical compositions and depth profiles are examined. Optical and current-voltage characteristics measurements of the films show that their transmittance and leakage current behaviors are strongly dependent upon the microstructures. O2 partial pressure in the rapid thermal annealing process is found to be an important parameter which determines crystallization, microstructures, and leakage current behaviors of the Bi4Ti3O12 thin films.
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