Yoichiro Shiba

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Malaria is a global health problem that threatens 300-500 million people and kills more than one million people annually. Disease control is hampered by the occurrence of multi-drug-resistant strains of the malaria parasite Plasmodium falciparum. Synthetic antimalarial drugs and malarial vaccines are currently being developed, but their efficacy against(More)
Amorphadiene, a sesquiterpene precursor to the anti-malarial drug artemisinin, is synthesized by the cyclization of farnesyl pyrophosphate (FPP). Saccharomyces cerevisiae produces FPP through the mevalonate pathway using acetyl-CoA as a starting compound. In order to enhance the supply of acetyl-CoA to the mevalonate pathway and achieve high-level(More)
Phospholipase A1 (PLA1) is a hydrolytic enzyme that catalyzes the removal of the acyl group from position 1 of lecithin to form lysolecithin. The PLA1 gene, which had been cloned from Aspergillus oryzae, was expressed in Saccharomyces cerevisiae and A. oryzae. Through the modification of the medium composition and the feeding conditions of substrate, the(More)
BACKGROUND & AIMS EM523, a motilin agonist, is intended to be used as a gastroprokinetic during the postprandial period, but the mechanism(s) by which EM523 stimulates postprandial contractions in the stomach has not been studied before. The aim of this study was to examine the mechanism of contraction-stimulating activity by EM523 in fed dogs. METHODS(More)
Carboxypeptidase Y (CPY; EC 3.4.16.1) is the yeast vacuolar protease. To have CPY secreted and to increase its secretion level, we tried to express the prepro-CPY gene under the control of the inducible GAL10 promoter or constitutive ENO1 promoter on a multicopy plasmid. In the strains KK4, PEP4, and A2-1-1A, carrying the CPY expression plasmid, active CPY(More)
Motilin-immunopositive cells (Mo cells) are known to be present in the upper small intestine of various species, including man. However, whether Mo cells are present in the rabbit gastrointestinal tract remained to be elucidated. Therefore, this study was designed to investigate the distribution of Mo cells in the rabbit gastrointestinal tract by the(More)
Many studies have suggested that 5-hydroxytryptamine (5HT, serotonin) plays an important role in the control of gastrointestinal motility. However, most of these studies have been carried out on guinea-pig ileum in vitro. Therefore, we investigated the mechanisms of action of 5HT on gastrointestinal motility in conscious guinea-pigs. In order to investigate(More)
We found that CPY production in Saccharomyces cerevisiae KS58-2D/pCY303 was increased by the addition of thiamine into the medium, while the addition of thiamine had no effect on cell growth. It became clear that the positive effect of thiamine was due to transcriptional increase, because the levels of CPYmRNA were increased according to the amount of(More)
BACKGROUND & AIMS EM523, a nonpeptide motilin agonist, is being developed for clinical use to improve delayed gastric emptying. The aim of this study was to examine the effect of EM523 on endogenous release of gut and pancreatic hormones in conscious dogs. METHODS Motility of the gastrointestinal tract was monitored using force transducers. Blood(More)
We compared the inhibitory effects of histamine and pentagastrin (PG) on motilin-induced upper gastrointestinal phase III activity in conscious dogs that had surgically prepared Heidenhain pouchs (HP). Contractile activity was measured by means of chronically implanted force transducers, and changes in pH of the perfusate through the HP were monitored(More)