Masaki Hirashima
Hisamitsu Pharmaceutical Co., Inc.
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Publication
Featured researches published by Masaki Hirashima.
Biochemical Journal | 2004
Yoshiro Saito; Noriko Sato; Masaki Hirashima; Gen Takebe; Shigeharu Nagasawa; Kazuhiko Takahashi
Human selenoprotein P (SeP), a selenium-rich plasma glycoprotein, is presumed to contain ten selenocysteine residues; one of which is located at the 40th residue in the N-terminal region and the remaining nine localized in the C-terminal third part. We have shown that SeP not only catalyses the reduction of phosphatidylcholine hydroperoxide by glutathione [Saito, Hayashi, Tanaka, Watanabe, Suzuki, Saito and Takahashi (1999) J. Biol. Chem. 274, 2866-2871], but also supplies its selenium to proliferating cells [Saito and Takahashi (2002) Eur. J. Biochem. 269, 5746-5751]. Treatment of SeP with plasma kallikrein resulted in a sequential limited proteolysis (Arg-235-Gln-236 and Arg-242-Asp-243). The N-terminal (residues 1-235) and C-terminal (residues 243-361) fragments exhibited enzyme activity and selenium-supply activity respectively. These results confirm that SeP is a bi-functional protein and suggest that the first selenocysteine residue is the active site of the enzyme and the remaining nine residues function as a selenium supplier.
PLOS ONE | 2010
Akihiro Higuchi; Kazuhiko Takahashi; Masaki Hirashima; Tetsuya Kawakita; Kazuo Tsubota
The ocular surface is always attacked by oxidative stress, and cornea epithelial cells are supposed to have their own recovery system against oxidative stress. Therefore we hypothesized that tears supply key molecules for preventing oxidative stress in cornea. The potential target key molecule we focused is selenoprotein P (SeP). SeP is a carrier of selenium, which is an essential trace element for many animals, for oxidative stress metabolism in the organism, and was extremely expressed in lacrimal gland. An experiment was performed with SeP eye drops in a rat dry eye model, prepared by removing the lacrimal glands. The anticipated improvement in corneal dry eye index and the suppression of oxidative stress markers were observed in SeP eye drop group. Furthermore, the concentration of SeP was significantly higher in dry eye patients compared with normal volunteers. Collectively, we concluded that tear SeP is a key molecule to protect the ocular surface cells against environmental oxidative stress.
Journal of Biochemistry | 2016
Masaki Hirashima; Takayuki Imamura; Kentaro Yano; Ryoichi Kawamura; Akihiro Meta; Yoshiyuki Tokieda; Toshihiro Nakashima
Fibrinogen is a large and complex glycoprotein containing two sets of each of three different chains (α, β and γ). There have been no reports of high-level expression of fibrinogen at commercial levels using mammalian cultured cells such as CHO cells because of the difficulty in highly expressing a protein with such a complex structure. We achieved high-level (1.3 g/l or higher) expression of recombinant human fibrinogen using CHO DG44 cells by optimizing the expression system and culture conditions. We also succeeded in establishing a high-recovery preparation method for recombinant fibrinogen that rarely yields degraded products. To characterize the properties of the recombinant human fibrinogen, we performed SDS-PAGE; western blotting of the α, β and γ chains using specific antibodies and scanning electron microscopy observations of fibrin fibres. We also evaluated the functional equivalence between recombinant fibrinogen and plasma fibrinogen with respect to the release of fibrinopeptides initiated by thrombin and its cross-linking properties. The basic properties of recombinant fibrinogen showed no apparent differences from those of plasma fibrinogen. Here, we report the development of methods for the culture and preparation of recombinant human fibrinogen of satisfactory quality that can be scaled up to the commercial level.
Journal of Biochemistry | 2006
Kenji Soejima; Hitomi Nakamura; Masaki Hirashima; Wataru Morikawa; Chikateru Nozaki; Tomohiro Nakagaki
Nutrition | 2005
Akira Andoh; Masaki Hirashima; Hiroaki Maeda; Kazunori Hata; Osamu Inatomi; Tomoyuki Tsujikawa; Masaya Sasaki; Kazuhiko Takahashi; Yoshihide Fujiyama
Biological & Pharmaceutical Bulletin | 2003
Masaki Hirashima; Takeshi Naruse; Hiroaki Maeda; Chikateru Nozaki; Yoshiro Saito; Kazuhiko Takahashi
Archive | 1999
Masaki Hirashima; Hiroaki Maeda; Chikateru Nozaki
Archive | 2004
Tomoko Ono; Kenji Soejima; Masaki Hirashima; Wataru Morikawa; Yoichi Sakata
Archive | 2002
Masaki Hirashima; Takeshi Naruse; Hiroaki Maeda; Chikateru Nozaki; Takeshi Goto; Katsuhiko Akiyama; Hidenao Fukushima
Archive | 2008
Masaki Hirashima; Takayuki Imamura; Hiroaki Maeda; Hitomi Owaki; Hitomi Tsugo; Kentaro Yano; 隆幸 今村; 浩明 前田; 瞳 尾脇; 正樹 平嶋; 健太郎 矢野; 瞳 都合