Papers by Author: Masanori Kikuchi

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Authors: Masanori Kikuchi, Toshiyuki Ikoma, D. Syoji, Hiroshi Matsumoto, Yoshihisa Koyama, Shigeru Itoh, Kazuo Takakuda, Kenichi Shinomiya, M. Tanaka
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Authors: Akinori Kochi, Masanori Kikuchi, Yuki Shirosaki, Satoshi Hayakawa, Akiyoshi Osaka
Abstract: Injectable hydroxyapatite/collagen nanocomposite (HAp/Col) artificial bone was prepared utilizing gelation of sodium alginate (Na-Alg). Mass ratio of the HAp/Col powder, with or without Ca adsorption treatment and Na-Alg (80-120, 300-400, 500-600 cP in viscosity at 10 g/dm3) was fixed at 90/10. Injectable HAp/Col was prepared by mixing the HAp/Col powder with Na-Alg solution at several powder (HAp/Col)/liquid (Na-Alg solution) ratios (P/L ratio, g/cm3). The result of consistency measurement suggested that the operability of injectable HAp/Col paste could be controlled by both the P/L ratio and the viscosity of Na-Alg solution. According to the consistency measurement and practical feelings during mixing, P/L=1/1.67 (80-120 cP) and 1/1.89 (300-400, 500-600 cP) were considered to be the highest P/L ratio allowed to mix the HAp/Col paste with a spatula. At the P/L=1/2.33 (80-120 cP), the paste prepared with the non-treated HAp/Col powder, placed in an incubator (37 °C,relative humidity 100%) for 24h, demonstrated gel-like property, while the paste prepared with Ca-treated HAp/Col powder did putty-like property. The difference in their property might be caused by the initial bonding behavior between Alg and Ca2+ after mixing. The setting time measurement with Gillmore needle was impossible because they were toosoft for this method. Even though, their operability and coalescence/settingproperty could be used as the injectable bone filler.
689
Authors: Masanori Kikuchi
Abstract: Effect of osteogenic activities of MG63 on the HAp/Col membrane was examined at day 10 and 14 by reverse-transcript and real-time polymerase chain reactions. Osteogenic activities of MG63 were upregulated by culture them on the HAp/Col membrane in comparison to those on tissue culture polystyrene. The novel three-dimensional HAp/Col scaffold was prepared from the HAp/Col wavy membrane. The cylindrical HAp/Col scaffold was successfully prepared and indicated at least 2.5-times higher compressive strength and Young's modulus compared to the previous HAp/Col composites. The novel scaffold could be useful for regenerative medicine.
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Authors: Yasushi Suetsugu, Toshiyuki Ikoma, Masanori Kikuchi, M. Tanaka
Abstract: Single crystals of AB-type carbonate apatite were grown by a CaCO3-Na2CO3 flux method under high pressure of Ar gas. The crystals obtained were hexagonal prismatic elongated along the c-axis with the length of 2mm and the diameter of 0.3mm at a maximum. Chemical formula was Ca8.8Na1.2[(PO4)4.8(CO3)1.2]CO3 and the space group was hexagonal P6 with cell parameters a = 0.9379(2)nm, c = 0.6935(1)nm. The detailed crystal structure determined with a reliability factor Rw = 0.047 indicated that the triangular plane of carbonate ion occupying B-site was slanted off the crystallographic mirror plane and the angle of the carbonate triangle with the mirror plane varied depending on Na-substitution of adjacent Ca sites whilst the A-site carbonate ion was parallel to the c-axis.
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Authors: Yasushi Suetsugu, Yuji Hotta, Masashi Iwasashi, Masataka Sakane, Masanori Kikuchi, Toshiyuki Ikoma, Tatsuhiko Higaki, Naoyuki Ochiai, M. Tanaka
Abstract: Porous ceramics of hydroxyapatite was fabricated utilizing the crystal growth of thin ice columns parallel to one another in gelatin gel containing hydroxyapatite nanoparticles. The obtained ceramics possessed unidirectional pore channels with a porosity of around 75% and showed compressive strength of up to 13.1 MPa. As control materials, porous hydroxyapatite ceramics with a directionless pore structure were also fabricated by isotropic freezing and compared with the unidirectional samples regarding compressive strength and tissue reaction in vivo. Although the porosity and pore size distribution were similar, the compressive strength and new bone formation ability of the unidirectional samples were significantly greater than those of the random structured porous ceramics.
1003
Authors: M. Otsuka, S. Shibasaki, Masanori Kikuchi
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Authors: Masanori Kikuchi, M. Tanaka
Abstract: Soft-nanotechnologies are based upon the synthesis technologies of nanomaterials and construction technologies of nanostructures by life forms. They are expected as new preparation methods for biomaterials that could be recognized as regular extracellular matrices (ECM) in our body by cells. We applied the soft-nanotechnology to synthesis of artificial bones made of HAp and collagen with bone-like nanostructure and examined their physical and biological properties. The nanocomposite obtained indicates bone-like nanostructure. Computer simulation and FT-IR suggested that the self-organization of HAp and collagen is based on chemical interaction between calcium ions on HAp surface and carboxy groups on collagen. After implantation in rats and dogs, the nanocomposites are resorbed by osteoclasts followed by osteogenesis; therefore, the nanocomposites are recognized as bone in the living body. Resorption rate can be controlled by crosslinkage. We also prepared sponge-like elastic porous body by gel-lyophilization technique using additional small amount of collagen solution. Bone tissue reactions of it are the same as the nanocomposites as prepared. The nanocomposites are now in clinical research in Japan to be commercialized in near future by Pentax Co.
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