Abstract: The present invention provides a pharmaceutical agent that is useful for preventing periodontal disease. The pharmaceutical agent contains a compound in which a mucin-type sugar chain-binding lectin is bound to a polypeptide having an integrin recognition sequence.

Abstract: In a GaAs field effect transistor of the invention, a gate layer is formed on a semi-insulative substrate. The gate layer is made of a conductive material forming a Schottky junction between the substrate and the gate layer. Source and drain regions are formed in the substrate to have a first conductivity type. Barrier layers are formed in the substrate to have a second conductivity type. The barrier layers are formed to surround the source and drain regions, and suppress a current component from leaking from the source and drain regions to the substrate when the field effect transistor is operative.