Tokyo University of Science

About: Tokyo University of Science is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 15800 authors who have published 24147 publications receiving 438081 citations. The organization is also known as: Tōkyō Rika Daigaku & Science University of Tokyo.

Functional Characterization of pH-Sensitive Organic Anion Transporting Polypeptide OATP-B in Human

Abstract: The pH-sensitive activity of human organic anion transporting polypeptide OATP-B, which is expressed at the apical membrane of human small intestinal epithelial cells, was functionally characterized. When initial uptake of estrone-3-sulfate, a typical substrate of OATP, was studied kinetically, we observed an increase in V(max) with decrease of pH from 7.4 to 5.0, whereas the change in K(m) was negligible. OATP-B-mediated uptake of estrone-3-sulfate was independent of sodium, chloride, bicarbonate, or glutathione, whereas the proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone exhibited a pH-dependent inhibitory effect, suggesting that a proton gradient is a driving force for OATP-B. When OATP-B was expressed in human embryonic kidney 293 cells, uptake activities for anionic compounds showed various kinds of pH sensitivity. Dehydroepiandrosterone-sulfate, estrone-3-sulfate, and fexofenadine were transported by OATP-B at both neutral and acidic pH, whereas estradiol-17beta-glucuronide, acetic acid, and lactic acid were not transported at all. Transport of taurocholic acid and pravastatin by OATP-B was observed only at acidic pH, demonstrating a pH-sensitive substrate specificity of OATP-B. Because the physiological pH close to the surface of intestinal epithelial cells is acidic, the roles of OATP-B in the small intestine might be different from those in other tissues, such as liver basolateral membrane. Although the driving force for OATP-B has not been fully established, the clarification of factors, such as pH, that affect the OATP-B-activity is essential for an understanding of the physiological and pharmacological relevance of the transporter in the small intestine.

An effective use of benzoic anhydride and its derivatives for the synthesis of carboxylic esters and lactones: A powerful and convenient mixed anhydride method promoted by basic catalysts

Abstract: Various carboxylic esters are obtained at room temperature in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2-methyl-6-nitrobenzoic anhydride with triethylamine by the promotion of a basic catalyst such as 4-(dimethylamino)pyridine. A variety of lactones are also prepared in high yields at room temperature from the corresponding ω-hydroxycarboxylic acids with use of 2-methyl-6-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine. A similar reaction occurs with triethylamine when using a catalytic amount of 4-(dimethylamino)pyridine 1-oxide as an effective promoter for the intramolecular condensation reaction. These methods are successfully applied to the synthesis of erythro-aleuritic acid lactone and an eight-membered-ring lactone moiety of octalactins A and B. The efficiency of the cyclizations is compared to those of other reported lactonizations.

βKlotho Is Required for Fibroblast Growth Factor (FGF) 21 Signaling through FGF Receptor (FGFR) 1c and FGFR3c

Abstract: Fibroblast growth factor (FGF) 21, a structural relative of FGF23 that regulates phosphate homeostasis, is a regulator of insulin-independent glucose transport in adipocytes and plays a role in the regulation of body weight. It also regulates ketogenesis and adaptive responses to starvation. We report that in a reconstituted receptor activation assay system using BaF3 cells, which do not endogenously express any type of FGF receptor (FGFR) or heparan sulfate proteoglycan, FGF21 alone does not activate FGFRs and that βKlotho is required for FGF21 to activate two specific FGFR subtypes: FGFR1c and FGFR3c. Coexpression of βKlotho and FGFR1c on BaF3 cells enabled FGF21, but not FGF23, to activate receptor signaling. Conversely, coexpression of FGFR1c and Klotho, a protein related to βKlotho, enabled FGF23 but not FGF21 to activate receptor signaling, indicating that expression of βKlotho/Klotho confers target cell specificity on FGF21/FGF23. In all of these cases, heparin enhanced the activation but was not e...

Nanoparticles Transferred from Pregnant Mice to Their Offspring Can Damage the Genital and Cranial Nerve Systems

Abstract: Nanomaterials are being used increasingly for commercial purposes, yet little is known about the potential health hazards such materials may pose to consumers and workers. Here we show that nano-sized titanium dioxide (TiO2), which is used widely as a photo-catalyst and in consumer products, administered subcutaneously to pregnant mice is transferred to the offspring and affects the genital and cranial nerve systems of the male offspring. Nanoparticles identified as TiO2 by energy-dispersive X-ray spectroscopy were found in testis and brain of exposed 6-week-old male mice. In the offspring of TiO2-injected mice, various functional and pathologic disorders, such as reduced daily sperm production and numerous caspase-3 (a biomarker of apoptosis) positive cells in the olfactory bulb of the brain, were observed. Our findings suggest the need for great caution to handle the nanomaterials for workers and consumers.

Study on polymer binders for high-capacity SiO negative electrode of Li-Ion batteries

Abstract: High-capacity SiO powder composite electrodes for rechargeable lithium-ion batteries are prepared with different polymer binders of poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), sodium carboxymethyl cellulose (CMCNa), and conventional poly(vinylidene fluoride) (PVdF). Electrode performance of the SiO composites highly depends on selection of binders, and their electrochemical reversibility is drastically improved by using PAA as the binder in comparison to the PVdF, CMCNa, and PVA binders. Coulombic efficiency at the initial cycle is improved for the SiO–PAA composite electrode, and the reversible capacity reaches 700–750 mAh g–1 for continuous fifty cycling test at a rate of 100 mA g–1. The improvement mechanism of SiO–PAA composite electrode is characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, self-discharge test, and adhesive strength test. Amorphous PAA polymer not only tightly binds but also covers the individual SiO particles. Mo...