Tetsuya Tajima
Eisai
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Featured researches published by Tetsuya Tajima.
European Journal of Pharmacology | 1994
Yasuhiro Akiyama; Kuniko Hara; Tetsuya Tajima; Sei-itsu Murota; Ikuo Morita
The effects of menatetrenone, a vitamin K2 homologue, on osteoclast-like cell formation in mouse bone marrow culture were investigated. After 7 days of incubation, menatetrenone at 10(-6) M, 3 x 10(-6) M and 10(-5) M dose dependently inhibited the tartrate-resistant acid phosphatase-positive multinucleated cell formation induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). The addition of menatetrenone for the last 3 days of the 7-day incubation period was required to inhibit formation of multinucleated cells in response to 1,25(OH)2D3. Moreover, the addition of 1,25(OH)2D3 for the last 3 days was essential for multinucleated cell formation, and this activity was markedly inhibited by the simultaneous addition of menatetrenone. The inhibitory effects of menatetrenone on multinucleated cell formation may contribute to its ameliorative action on bone loss in vivo, and may indicate a new mechanism of vitamin K2 activity in bone metabolism.
Bone | 1993
Kuniko Hara; Yasuhiro Akiyama; Isao Ohkawa; Tetsuya Tajima
This study was carried out to evaluate the effect of menatetrenone, a vitamin K2 with 4 isoprene units, on prednisolone-induced bone loss. Three experiments were performed in rats which received menatetrenone as a dietary supplement. In experiment 1, a soluble form of prednisolone, dissolved in drinking water, was administered to rats at 7 mg/kg/day for 9 weeks. The length, dry weight, and bone density of femurs and tibiae, as well as urinary gamma-carboxyglutamic acid (Gla) content, were significantly lower in the prednisolone-control group than in the intact group. Menatetrenone (17 mg/kg/day) significantly inhibited the decrease in these bone parameters, especially in tibiae, and completely inhibited the decrease in urinary Gla content. In experiments 2 and 3, prednisolone (10 mg/kg), dissolved in cottonseed oil, was given to rats intramuscularly three times a week for 4 and 10 weeks, respectively. In experiment 2, bone length, bone strength and calcium content in the femur were reduced by 4-week prednisolone treatment. These reductions were significantly improved by menatetrenone (21 mg/kg/day). In experiment 3, 10-week prednisolone treatment reduced bone length and the calcium and hydroxyproline content of the femur. Menatetrenone (0.4, 10, and 50 mg/kg/day) significantly inhibited the reduction of calcium content in the femur. These results suggest that menatetrenone may inhibit the bone loss induced by corticosteroid treatment.
Analytical Biochemistry | 1991
Motoaki Bessho; Fumitaka Ohsuzu; Shigeki Yanagida; Nobuhiro Sakata; Noboru Aosaki; Tetsuya Tajima; Haruo Nakamura
To compare the extractability of creatine phosphate with that of ATP by alcohol extraction, both compounds were extracted from normal perfused rat heart tissues by using various stepwise concentrations of ethanol and 0.4 M HClO4. Powdered samples (6-15 mg wet wt) from the freeze-clamped tissues were homogenized in 2 ml of the ethanol solutions. After centrifugation, the supernatant was removed; each centrifuged sediment was rehomogenized with 2 ml of 0.4 M HClO4 and centrifuged. The supernatant was neutralized with 0.4 m KHCO3. The same powdered samples were directly homogenized with 2 ml of 0.4 M HClO4 and treated in the same manner. Only a small amount of ATP in the tissues was extracted by an 85% or higher concentration of ethanol. Further, about 13% of the tissue ATP was not extractable by the subsequent perchloric acid extraction. In contrast to ATP, creatine phosphate in the tissues was partially extracted by 95% ethanol and nearly all of the tissue creatine phosphate was extracted by 70% ethanol. The total creatine phosphate obtained by 70% ethanol and by subsequent perchloric acid extraction was significantly higher than that obtained by direct perchloric acid extraction. From these results, it was concluded that the extractability of creatine phosphate in the tissue by alcohol extraction is clearly different from that of ATP. Additionally, the stepwise extraction is recommended as a useful method for the extraction of energy metabolites in perfused rat heart tissue.
Biochemical Pharmacology | 1995
Yasuhiro Akiyama; Kuniko Hara; Akira Matsumoto; Sumiko Takahashi; Tetsuya Tajima
To examine the physiological activities of vitamin K2 (menaquinone, MK) homologues with different numbers of isoprene units, MK with 1-14 isoprene units and menadione (MK-0) were administered to rats with hypoprothrombinaemia, and the absorption, concentration in liver and ameliorating effect of these MK on hypoprothrombinaemia were compared. Hypoprothrombinaemia was induced by giving a vitamin K-deficient diet and warfarin (0.06 mg/kg body weight) for 8 days. Before MK treatment, the MK were undetectable in plasma and liver. At 6 hr after oral MK administration (0.1 mg/kg): MK was not detected in the plasma in rats treated with MK with 1, 2, 3 or more than 12 isoprene units; the MK level in the liver was increased but blood coagulation activity was not improved in rats treated with MK with 0, 9, 10 or 11 isoprene units; the MK level in the liver was increased and hypoprothrombinaemia was slightly improved in rats treated with MK with 7 or 8 isoprene units; and the MK level in the liver was increased and hypoprothrombinaemia was markedly improved in rats treated with MK with 4, 5 or 6 isoprene units. Almost identical results were observed 3 hr after intravenous injection of MK with 4, 5 or 6 isoprene units (10 nmol/kg). These findings suggest that the number of isoprene units of MK is an important factor in its absorption and incorporation into the liver and that the ameliorating effect of MK on hypoprothrombinaemia does not parallel their concentrations in the liver.
Analytical Biochemistry | 1989
Motoaki Bessho; Tetsuya Tajima; Shingo Hori; Toru Satoh; Keiichi Fukuda; Shingo Kyotani; Yozo Ohnishi; Yoshiro Nakamura
To clarify the most quantitative extraction method for the determination of NAD and NADH in dog heart tissues, both pyridine dinucleotides were extracted from normal and ischemic heart tissues by the Klingenberg method and the Karp method and determined by bacterial luciferase. Tissues from normal beating hearts were sampled by a specially developed freeze-clamping device in 120 ms to minimize ischemic NADH production during sampling. Samples were obtained from both the subendocardium and the subepicardium of the frozen heart tissues. In the Klingenberg method, NAD and NADH were separately extracted with 0.6 M HClO4 and 0.5 M KOH in 50% ethanol, respectively. Both pyridine dinucleotides were simultaneously extracted with 70% ethanol in 0.01 M phosphate buffer in the Karp method. The mean values of NAD and NADH in the normal tissues were 5.08 +/- 0.84 and 0.18 +/- 0.10 nmol/mg protein, respectively, with a NAD/NADH ratio of 25-30 by the Klingenberg method. While the values by the Karp method were 4.37 +/- 0.68 and 0.09 +/- 0.04 nmol/mg protein, with a NAD/NADH ratio of 55-65. The efficiency of extraction of both pyridine dinucleotides by the Karp method was lower than that by the Klingenberg method in all tested samples and states of the tissues. These results suggest that the Klingenberg method is preferable for the extraction of both pyridine dinucleotides from dog heart tissues and that the mean NAD/NADH ratio in normal dog heart tissues is 25-30.
Journal of Bone and Mineral Research | 2009
Kuniko Hara; Yasuhiro Akiyama; Tetsuya Tajima; Masataka Shiraki
Japanese Journal of Pharmacology | 1993
Yasuhiro Akiyama; Kuniko Hara; Isao Ohkawa; Tetsuya Tajima
Japanese Journal of Pharmacology | 1997
Hidetoshi Kawashima; Yoshikage Nakajima; Yoshio Matubara; Junichi Nakanowatari; Taneo Fukuta; Saburo Mizuno; Sumiko Takahashi; Tetsuya Tajima; Tetsuya Nakamura
Folia Pharmacologica Japonica | 1994
Kuniko Hara; Yasuhiro Akiyama; Takashi Tomiuga; Masatoshi Kobayashi; Tetsuya Nakamura; Tetsuya Tajima
Japanese Journal of Pharmacology | 1994
Takashi Tomiuga; Masatoshi Kobayashi; Yoshikage Nakajima; Motoaki Bessho; Yoshinori Katoh; Kuniko Hara; Yasuhiro Akiyama; Tetsuya Nakamura; Tetsuya Tajima