Etching characteristics of nondoped GaN films with the polar surface in KOH solution have been investigated. It is confirmed that the continuous etching in KOH solution takes place only for the GaN films with N-face (Ϫc) polarity independent of the deposition method and growth condition. It is found by x-ray photoelectron spectroscopy ͑XPS͒ analysis for the Ga face (ϩc) and N-face (Ϫc) GaN films that the atomic composition of the ϩc surface is not changed before and after dipping in KOH solution and that on the other hand, the amount of oxygen ͑oxide͒ on the Ϫc surface is significantly decreased by the etching. It is also found that the band bending increases by Ϫ0.4Ϯ0.2 and 0.6Ϯ0.2 eV for the ϩc and Ϫc surfaces after etching, respectively. This is discussed in terms of the surface chemistry. Based on the XPS result, the selective etching of the GaN polar surface is pointed out to originate from bonding configuration of nitrogen at the surface.

The infrared absorption spectra of CO2 adsorbed on MgO and GaO were measured in the wide region 700–4000 cm−1 at various amounts of adsorbed CO2 and temperatures of adsorption and desorption. It has been found that both uni- and bidentate carbonates are formed on MgO when a small amount of CO2 is adsorbed and that unidentate carbonates predominate as the amount of adsorbed CO2 is increased. On the other hand, only unidentate species were formed on CaO at room temperature independently of the amount of adsorbed CO2, but bidentate species were also formed on CaO when the temperature of adsorption was high. The unidentate carbonates formed on both MgO and CaO at room temperature partially changed to bidentate carbonates upon evacuation at higher temperatures. The correlation between Δv=|v1–v5| and the partial charge on oxygen atoms of various oxides, which corresponds to basic strength on the surface, was examined.

We have reported previously that alterations to beta-catenin occur frequently in adamantinomatous craniopharyngioma. Based on its histological resemblance to some odontogenic tumors, we suspected the presence of common genetic alterations among these tumors. To address this issue, 11 cases of calcifying odontogenic cyst (COC) and 20 cases of ameloblastoma were investigated for the presence of beta-catenin mutations and beta-catenin expression. Ten COCs were successfully analyzed by direct sequencing, and nine of them were found to harbor somatic beta-catenin mutations. Immunohistochemically, all of the COCs showed nuclear and cytoplasmic expression of beta-catenin with a heterogeneous pattern. No beta-catenin mutations were found in ameloblastomas, except for one case of the follicular type. All follicular ameloblastomas exhibited moderate nuclear and cytoplasmic accumulation of beta-catenin, in contrast to the predominantly membranous expression seen in the plexiform type. beta-Catenin mutation is considered to be a characteristic genetic feature of COC, and may play a critical role in its histogenesis. Although ameloblastoma closely resembles COC histologically, the two have genetically distinctive features.

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Intercellular adhesion molecule-1 (ICAM-1) is a transmembrane glycoprotein in the immunoglobulin superfamily, which plays an important role in cell adhesion and signal transduction. Although ICAM-1 is believed to play a role in several malignancies, it is still uncertain whether or not ICAM-1 expression contributes to cancer progression. In this study, we performed clinicopathological and cell biological analyses of ICAM-1 expression in oral squamous cell carcinoma (SCC). First, we examined the ICAM-1 expression in tongue SCC immunohistochemically, and revealed that ICAM-1 was expressed predominantly at the invasive front area of tongue SCC. ICAM-1 expression at the invasive front area was correlated with invasion, lymph node metastasis and increased blood and lymphatic vessel density of the tongue SCC. The relationship between ICAM-1 expression and clinicopathological factors were consistent with the increased proliferation, invasion and cytokine-production activities of ICAM-1-transfected SCC cells. Second, we analyzed the relationship between macrophages and ICAM-1-expressing tongue SCC cells because ICAM-1 is known to act as a ligand for adhesion of immune cells. Increased ICAM-1 expression in tongue SCC was correlated with increased macrophage infiltration within SCC nests. Moreover, macrophage/SCC-cell adhesion through ICAM-1 molecule was revealed using an in vitro cell adhesion and blockade assay. These findings indicate that ICAM-1 plays an important role in tongue SCC progression, which may result from the SCC-cell activity, angiogenic activity, lymphangiogenic activity and macrophage/SCC-cell adhesion.Intercellular adhesion molecule-1 (ICAM-1; also known as CD54) is a transmembrane glycoprotein in the immunoglobulin superfamily present at basal levels in a wide variety of cell types and is upregulated in response to a number of inflammatory mediators. During the inflammatory process, ICAM-1 expressed on endothelial cells interacts with the b2 integrin counter-receptors CD11a/CD18 (also known as lymphocyte function-associated antigen-1, LFA-1) and CD11b/ CD18 (also known as macrophage antigen-1, Mac-1) on the surface of immune cells, facilitating their transendothelial migration from the circulation to the site of inflammation.