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Dive into the research topics where Masami Kojima is active.

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Featured researches published by Masami Kojima.


European Journal of Pharmacology | 1990

Effect of a thromboxane A2 synthetase inhibitor (OKY-046.HCl) on airway hyperresponsiveness in guinea pigs.

Hidetada Komatsu; Yasuo Takehana; Shinji Kikuchi; Masami Kojima; Shuichiro Hamano; Hiroshi Kusama; Tadao Okegawa; Shigeru Ikeda

We studied the effect of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate (OKY-046.HCl), a specific thromboxane (TX) A2 synthetase inhibitor, on airway hyperresponsiveness of guinea pigs. OKY-046.HCl (30-100 mg/kg, intraduodenally (i.d.) or orally (p.o.)) suppressed dose dependently the airway hyperresponsiveness to acetylcholine (ACh) induced by formyl-methionyl-leucyl-phenylalanine (FMLP), platelet activating factor (PAF) and repetitive antigen. OKY-046.HCl (100 mg/kg) also inhibited the increase in TXB2 in bronchoalveolar lavage fluid (BALF) induced by FMLP, PAF and antigen. Aspirin 10 or 30 mg/kg i.d. or p.o.) suppressed the airway hyperresponsiveness induced by FMLP and PAF but not by antigen. Azelastine (10 mg/kg i.d.) was ineffective on PAF- and antigen-induced airway hyperresponsiveness. TXA2 mimetic drugs caused airway hyperresponsiveness that was not inhibited by OKY-046.HCl (30 mg/kg i.v.). Furthermore, OKY-046.HCl showed no effect on propranolol- and physostigmine-induced airway hyperresponsiveness which did not accompany TXB2 generation in BALF. The number of eosinophils in BALF increased after FMLP exposure, an effect which was not inhibited by OKY-046.HCl. These results suggest that OKY-046.HCl inhibits airway hyperresponsiveness by suppressing TXA2 generation. We suggest that OKY-046.HCl will be a new antiasthmatic drug.


Pharmacology | 1999

Effect of Ozagrel on Locomotor and Motor Coordination after Transient Cerebral Ischemia in Experimental Animal Models

Kiyoshi Ichikawa; Shigeki Tazawa; Shuichiro Hamano; Masami Kojima; Seiji Hiraku

The effect of ozagrel, a selective thromboxane A2 (TXA2) synthetase inhibitor, on the obstruction after cerebral ischemia-reperfusion was studied in experimental animal models. The reduced spontaneously locomotor activity and the obstruction of motor coordination were improved by the administration of ozagrel in the conscious cerebral ischemia-reperfusion mouse model. Ozagrel suppressed the decrease in specific gravity of the brain tissue induced by the occlusion-reperfusion in the conscious cerebral ischemia-reperfusion SHR model, and recovered the postischemic decrease in cortical PO2 after middle cerebral artery occlusion-reperfusion in cats. The level of TXB2, a metabolite of TXA2, in the brain increased after the cerebral ischemia-reperfusion, and ozagrel prevented this increase. Additionally, ozagrel also increased the level of 6-keto-PGF1α, a metabolite of prostaglandin I2 (PGI2), in the brain tissue after cerebral ischemia-reperfusion, and the administration of PGI2 improved the reduced spontaneous locomotor activity in the conscious cerebral ischemia-reperfusion mouse model. Our data suggest that ozagrel suppressed the obstruction following cerebral ischemia-reperfusion by preserving the cerebral blood flow via preventing the increase in TXA2 and causing an increase in the PGI2 level.


Bone and Mineral | 1994

In vitro effect of KCA-098, a derivative of coumestrol, on bone resorption of fetal rat femurs

Naoyuki Tsutsumi; Kohtaro Kawashima; Nobuhiko Arai; Hideo Nagata; Masami Kojima; Arao Ujiie; Hiroyoshi Endo

The effects of 3,9-bis(N,N-dimethylcarbamoyloxy)-5H-benzofuro[3,2-c]quinoli ne-6-one (KCA-098), a derivative of coumestrol, on bone resorption was studied in organ cultures of 20-day fetal rat femora. KCA-098 increased the length, dry weight, and calcium and phosphorus contents of parathyroid hormone (PTH)-treated fetal rat femur. As PTH significantly reduced the calcium and phosphorus contents of the femora, probably by stimulating bone resorption, KCA-098 seems to inhibit bone resorption. In fact, KCA-098 inhibited the PTH-induced release of 45Ca from pre-labeled fetal rat femora into the medium in organ culture. Coumestrol also inhibited the release of 45Ca from bone into the medium. However, KCA-098 did not increase the uterine weight of ovariectomized rats, whereas coumestrol did so. Thus KCA-098 is a unique, new inhibitor of bone resorption that has no estrogenic activity.


Journal of Bone and Mineral Metabolism | 1999

Treatment effects of bisphosphonates on ovariectomy-induced osteopenia in rats: Comparison between clodronate and etidronate

Fumiaki Itoh; Masataka Shiraki; Hanako Komatsu; Yohsuke Imai; Yoshimitsu Komatsu; Fumie Taya; Masami Kojima

Abstract: We studied the effects of clodronate and etidronate on bone loss induced by ovariectomy (OVX) in rats. Drug administration was initiated 8 weeks after the surgery and continued for 12 weeks (twice per week, s.c.). Lumbar (L4–L5) bone mineral density (BMD) and femoral BMD in the sham-operated group were increased to 113% and 114%, respectively, whereas those in OVX group were suppressed to 98.8% and 105%. Clodronate significantly restored the suppressed BMD over the entire dose range used (4–25 mg/kg). Etidronate restored BMD only at 4 mg/kg. In a histomorphometric analysis of lumbar vertebrae, both bisphosphonates depressed the amount of labeled surface, which was increased by OVX, to 11.9%–20.1% of the OVX group value for clodronate and to 0.23%–9.7% of the OVX group value for etidronate. The osteoid area was significantly increased by etidronate treatment over the entire dose range (OS/BS, 175%–295%). On the other hand, the osteoid area in the clodronate group did not increase at any dose tested (OS/BS, 38.1%–49.9%). Urinary excretion of deoxypyridinoline and plasma level of osteocalcin were elevated in the OVX group (162%–182% and 123%, respectively), suggesting that OVX enhanced bone turnover. Both bisphosphonates suppressed the bone turnover accelerated by OVX, and the data indicated that both bisphosphonates recovered BMD by means of inhibition of bone resorption. These data suggested that clodronate and etidronate reversed osteopenia induced by ovariectomy in rats. As judged from the dose response of BMD and histomorphometric findings, clodronate showed a wider safety margin than etidronate.


Japanese Journal of Pharmacology | 1988

Study of the Mechanism of Inhibitory Action of Tranilast on Chemical Mediator Release

Hidetada Komatsu; Masami Kojima; Naoyuki Tsutsumi; Shuichiro Hamano; Hiroshi Kusama; Arao Ujiie; Shigeru Ikeda; Masayuki Nakazawa


The Journal of Urology | 2003

Functional Characterization of β-adrenoceptor Subtypes in the Canine and Rat Lower Urinary Tract

Hiroo Takeda; Akane Matsuzawa; Yasuhiko Igawa; Yoshinobu Yamazaki; Kouich Kaidoh; Satoshi Akahane; Masami Kojima; Hiroshi Miyata; Masuo Akahane; Osamu Nishizawa


Biological & Pharmaceutical Bulletin | 1996

Dopamine Receptor Affinities in Vitro and Stereotypic Activities in Vivo of Cabergoline in Rats

Masaharu Miyagi; Fumiaki Itoh; Fumie Taya; Nobuhiko Arai; Masayuki Isaji; Masami Kojima; Arao Ujiie


Japanese Journal of Pharmacology | 1988

Mechanism of Inhibitory Action of Tranilast on the Release of Slow Reacting Substance of Anaphylaxis (SRS-A) In Vitro: Effect of Tranilast on the Release of Arachidonic Acid and Its Metabolites

Hidetada Komatsu; Masami Kojima; Naoyuki Tsutsumi; Shuichiro Hamano; Hiroshi Kusama; Arao Ujiie; Shigeru Ikeda; Masayuki Nakazawa


Japanese Journal of Pharmacology | 1984

Effect of N-5' on histamine release from rat peritoneal exudate cells induced by calcium ionophore and ATP.

Arao Ujiie; Masami Kojima; Jun Naito; Masayuki Nakazawa; Akihide Koda


Biological & Pharmaceutical Bulletin | 1996

Effect of cabergoline, a long-acting dopamine D2 agonist, on reserpine-treated rodents

Masaharu Miyagi; Nobuhiko Arai; Fumie Taya; Fumiaki Itoh; Yoshimitsu Komatsu; Masami Kojima; Masayuki Isaji

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Akihide Koda

Gifu Pharmaceutical University

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