Papers by Author: Atsushi Yamazaki

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Authors: Yu Sogo, Yuusuke Ishikawa, Nao Kondo, Eiji Uchimura, Ayako Oyane, Tadao Ohno, Atsuo Ito, Atsushi Yamazaki
Abstract: Fibronectin (FN) and type I collagen (Col), which are kinds of extracelluar matrices, were coprecipitated with calcium phosphate to form a composite layer on a hydroxyapatite (HAP) ceramic using a supersaturated calcium phosphate solution (CP solution). The amounts of protein immobilized in the layers were determined to be 20.97±3.04 µg·cm-2 for FN, 5.26±0.19 µg·cm-2 for Col and 21.72±2.30 µg·cm-2 for simultaneously immobilized FN and Col. When osteoblastic MC3T3-E1 cells were cultured on the HAP ceramics with the composite layer containing FN and/or Col, calcified tissue was formed through the activity of the cells. The result showed that the composite layer accelerated the differentiation of MC3T3-E1 to bone-forming cells. It is assumed that osteoblastic cells in alveolar bone migrated and differentiated on the surface of the tooth roots when the artificial tooth roots were covered with the composite layer.
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Authors: Toshiyuki Ikoma, Yosinori Kubo, Atsushi Yamazaki, Masaru Akao, M. Tanaka
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Authors: Yuusuke Ishikawa, Nao Kondo, Yu Sogo, Atsuo Ito, Eiji Uchimura, Ayako Oyane, Tadao Ohno, Atsushi Yamazaki, Takashi Ushida, Katsuko S. Furukawa
Abstract: Fibronectin (FN)-apatite composite layers were formed on a hydroxyapatite (HAP) ceramic using supersaturated calcium phosphate (CP) solutions. The surface roughness of the composite layer could be controllable by changing the magnesium (Mg) concentration in the CP solution. The higher the Mg concentration, the smaller the apatite crystals in the layer were. The thickness of the layer formed in the CP solution containing 1.5 mM Mg decreased to 68% that formed in the Mg-free CP solution. The amount of FN immobilized in the layer was almost constant regardless of Mg concentration in the CP solution in the range from 0 to 1.5 mM. The results of the present study revealed that a thin FN-apatite composite layer with a smooth surface and a high protein content is formed in a CP solution at a Mg concentration of 1.5 mM.
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Authors: Ayako Oyane, Yuusuke Ishikawa, Yu Sogo, Atsushi Yamazaki, Katsuko S. Furukawa, Takashi Ushida, Atsuo Ito
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Authors: Yu Sogo, Daiki Yokoyama, Atsuo Ito, Atsushi Yamazaki, Racquel Z. LeGeros
Abstract: Abstract. Fluoride (F-)-substituted type-B carbonate-containing hydroxyapatites (CHAPs) were prepared as bone substitutes with a F-releasing ability. The F- contents in the F-substituted CHAPs were 16-22 times larger than that in normal adult human bones. The carbonate contents in the F-substituted CHAPs corresponded to that in human bones. The F-substituted CHAPs released F- in an acetic acid – sodium acetate buffer at pH 4.9; within only 3 h, the F- concentration in the buffer increased to more than 63.9 µg L-1, which was 1.5~8.9 times higher than that in a body fluid of normal adult humans. Although the F- concentration rapidly decreased probably due to the precipitation of a certain phase containing F-, the F-substituted CHAPs exhibited the ability to increase the F- concentration in a body fluid by bone resorption. Therefore, it is expected that the F-substituted CHAPs will be feasible as a F-releasing material for promoting bone formation.
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Authors: Hajime Ohsawa, Atsuo Ito, Yu Sogo, Atsushi Yamazaki, Tadao Ohno
Abstract: Highly disgregated dicalcium phosphate anhydrate (DCP) nanoparticles 240-367 nm in diameter were synthesized by a reaction between calcium carbonate and phosphoric acid. When the DCP nanoparticles were immersed in a supersaturated calcium phosphate solution containing bovine serum albumin (BSA) and ethanol, BSA/DCP nano-composite particles were synthesized through the coprecipitation of BSA on the DCP nanoparticles. BSA was firmly immobilized on the BSA/DCP nano-composite particles. The results of this study suggest that DCP nanoparticles appear to be useful as a drug delivery vehicle.
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Authors: Naoko Kobayashi, Kazuo Onuma, Ayako Oyane, Atsushi Yamazaki
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