Publications by authors named "Yasumichi Kogai"

Electron beam melting (EBM) has been used to fabricate three-dimensional (3D) porous Ti-6Al-4V surfaces for acetabular cups in total hip arthroplasty. However, there are radiographic concerns regarding poor implant fixation and bone ingrowth around electron beam melted (EBMed) 3D porous cups. We hypothesize that nano-hydroxyapatite (nHA) coating can promote bone ingrowth and thus decrease the occurrence of radiolucent lines around EBMed 3D porous cups.

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Background: Thirteen patients with chlorhexidine-silver sulfadiazine-impregnated catheters have experienced serious anaphylactic shock in Japan. These adverse reactions highlight the lack of commercially available catheters impregnated with strong antibacterial chemical agents. A system should be developed that can control both biocompatibility and antibacterial activity.

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We obtained hydroxyapatite (HAp) materials as a block by mixing HAp nanoparticles and polymer, and then calcining the mixtures. The surface morphology of the HAp materials was tuned by varying heat treatment conditions. After calcining the mixtures at 1200 or 800°C for 4h, the surface morphology of the HAp materials was flat or convexo-concave, respectively.

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To develop a nanoscaled coating material for medical devices possessing weak antibacterial activity, dispersible and crystalline fluorinated hydroxyapatite (F-HAp) nanoparticles were prepared using antisintering agent to avoid calcination-induced sintering. The product was identical to fluorapatite, as determined by X-ray diffraction and Fourier transform infrared spectroscopy. The primary particles generally showed rod-shaped morphology with a length of 367 ± 67 nm and a width of 223 ± 21 nm measured by scanning electron microscopy (SEM).

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Various particles such as Alum or silica are known to act as an adjuvant if co-administered with vaccine antigens. Several reports have demonstrated that the adjuvanticity is strongly affected by the physicochemical properties of particles such as the size, shape and surface charge, although the required properties and its relationship to the adjuvanticity are still controversial. Hydroxyapatite particle (HAp) composed of calcium phosphate has been shown to work as adjuvant in mice.

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Purpose: Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity.

Methods: The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.

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