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  • 1
    Electronic Resource
    Electronic Resource
    Electrochemical Ceramic Device for Hydrogen-Phosphate Ion Sensor (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 45 (Oct. 2006), p. 1792-1798 
    Details
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: Novel sol-gel processing techniques of ceramic materials were developed for designingnew functional environmental ion sensors. Wet-chemical preparation methods for metal-oxidethin-films, perovskite-type oxide thin-films, and solid-electrolyte discs could be developed by usingsolution techniques based on polymer precursors, etc. New electrochemical sensing techniques tohydrogen-phosphate ion with high sensitivity and selectivity were developed by the use ofceramic-based sensors. A sol-gel processing technique was developed for the preparation ofLa-based perovskite-type oxide thin-films using an acetylacetone (AcAc)-modified poly(vinylalcohol) (PVA)-based polymeric precursor method. The AcAc modified PVA-based sol made itpossible to deposit a thin-film as well as to lower the sintering temperatures. The La0.8Sr0.2CoO3perovskite-type oxide thin-film electrode prepared at 500°C showed good properties ofamperometric sensing to hydrogen-phosphate ion. A new solid-electrolyte ion sensor device using aNa+-ion conductor (Na5DySi4O12: NaDyCON) as an impedancemetric transducer and aperovskite-type oxide thin-film as a receptor has been further developed. The AC impedance of thedevice with a LaCoO3 receptor was found to vary logarithmically with increasing K2HPO4concentration between 1.0 x 10-5 and 1.0 x 10-2 M at 10 kHz. The 90% response time was ca. 2 minat room temperature. The sensor showed a little sensitivity to NO3- at higher concentration, while noresponse was observed to the examined anions of Cl- and ClO4-
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.1792.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Transport Characteristics of Ceftibuten (7432-S), a New Oral Cephem, in Rat Intestinal Brush-Border Membrane Vesicles: Proton-Coupled and Stereoselective Transport of Ceftibuten (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 302-307 
    Details
    ISSN: 1573-904X
    Keywords: ceftibuten ; proton-coupled uphill transport ; rat intestinal brush-border membrane vesicles ; stereoselective transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The transport characteristics of ceftibuten in rat intestinal brush-border membrane vesicles were investigated by a rapid filtration technique. Ceftibuten uptake was markedly stimulated by an inwardly directed H+ gradient (pH 7.5 inside, pH 5.5 outside) in comparison with that in the absence of a H+ gradient. The uptake at 30 sec was four times greater than that observed at equilibrium (overshoot phenomenon), while the H+ gradient-stimulated uptake of ceftibuten was markedly reduced in the presence of FCCP, a protonophore. These results suggested H+-coupled uphill transport of ceftibuten. In contrast, an inwardly directed Na+ gradient had no effect on ceftibuten uptake. The valinomycin-induced K+ diffusion potential (inside positive) significantly stimulated the ceftibuten uptake, suggesting net transfer of the negative charge. In contrast to the cis-isomer ceftibuten, the trans isomer of ceftibuten is not readily absorbed from the intestine, and its uptake was found not to be affected by a H+ gradient. Since the lipophilicity of the trans isomer is similar to that of ceftibuten, the uptake process appears to be stereoselective. The initial uptake of ceftibuten and its analogue cefaclor was concentration dependent under a H+ gradient. The apparent K m value was 0.2 mM for ceftibuten and 3.0 mM for cefaclor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015994323639
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  • 3
    Electronic Resource
    Electronic Resource
    Transport Characteristics of Ceftibuten, a New Oral Cephem, in Rat Intestinal Brush-Border Membrane Vesicles: Relationship to Oligopeptide and Amino β-Lactam Transport (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 308-312 
    Details
    ISSN: 1573-904X
    Keywords: ceftibuten ; transport ; brush-border membrane ; oligopeptide ; amino β-lactam ; oral cephem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ceftibuten undergoes H+-coupled uphill transport across rat small intestinal brush-border membrane vesicles. The effects of amino acids, peptides, folate, and β-lactams on the uptake of ceftibuten were examined. Uptake of ceftibuten was competitively inhibited by dipeptides or tripeptides. A counter-transport effect on ceftibuten uptake was observed in the vesicle preloaded with these peptides, and the transport was temporarily against a concentration gradient (overshooting). On the other hand, ceftibuten uptake was not changed by amino acids and a tetrapeptide. Therefore, ceftibuten is predominantly transported via the oligopeptide transport system in the brush-border membranes. The relationship of ceftibuten transport to folate and other oral antibiotics was also investigated. Cyclacillin, cephradine, and cefadroxil exhibited both inhibitory and countertransport effects, but folate, cefaclor, and cephalexin showed only a slight inhibitory effect. As the transport of cefaclor showed no uphill uptake in the presence of a H+ gradient and its H+ stimulated uptake was small, a H+ gradient-independent carrier-mediated system seems to participate in its transport. These findings suggest that two different carrier-mediated transport systems, H+ gradient dependent and independent, may exist for oral cephems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015946407709
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