The changes induced by biologically active substances in the permeability to K+ and calcein of liposomes composed of egg phosphatidylcholine and cholesterol were measured simultaneously in order to rapidly screen the sizes of pores formed in a membrane, using different sized markers. The substances examined in the present study were classified into three types based on differences in the rates at which K+ and calcein were released. The first type released only K+, and included gramicidin A. The second type predominantly released K+, preceding the release of calcein, and included amphotericin B and nystatin. The third type, including antimicrobial peptides, such as gramicidin S, alamethicin, and melittin, and several membrane-active drugs, like celecoxib (non-steroidal anti-inflammatory drug), 1-dodecylazacycloheptan-2-one (named azone; skin permeation enhancer), and chlorpromazine (tranquilizer), caused the release of K+ and calcein simultaneously. Thus, the sizes of pores formed in a liposomal membrane increased in the following order: types one, two, and three. We determined the size more precisely by conducting an osmotic protection experiment, measuring the release of calcein in the presence of osmotic protectants of different sizes. The radii of pores formed by the second type, amphotericin B and nystatin, were 0.36 - 0.46 nm, while the radii of pores formed by the third type were much larger, 0.63 - 0.67 nm or more. The permeability changes induced by substances of the third type are discussed in connection with a transient pore formed in a lipid packing mismatch taking place during the phase transition of dipalmitoylphosphatidylcholine liposomes.
en-copyright= kn-copyright= en-aut-name=KatsuTakashi en-aut-sei=Katsu en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ImamuraTomonori en-aut-sei=Imamura en-aut-mei=Tomonori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KomagoeKeiko en-aut-sei=Komagoe en-aut-mei=Keiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MasudaKazufumi en-aut-sei=Masuda en-aut-mei=Kazufumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MizushimaTohru en-aut-sei=Mizushima en-aut-mei=Tohru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=5 en-affil= kn-affil=Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University END start-ver=1.4 cd-journal=joma no-vol=134 cd-vols= no-issue=2 article-no= start-page=516 end-page=520 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=20080530 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Oxygen electrode as a new tool to evaluate hydroxyl radical-scavenging ability en-subtitle= kn-subtitle= en-abstract= kn-abstract=An oxygen electrode was applied to determine hydroxyl radical ((OH)-O-center dot) levels for the first time. The method is based on the determination of (OH)-O-center dot generated by the Fenton reaction using the reaction of (OH)-O-center dot with a scavenger and the resulting radical consuming an oxygen molecule stoichiometrically. Thus, the (OH)-O-center dot-scavenging abilities of antioxidant reagents, as well as the concentration of (OH)-O-center dot, can be determined by the measurement of consumption of dissolved oxygen using an oxygen electrode. A good correlation between the present method and conventional colorimetry was obtained for the estimation of the (OH)-O-center dot-scavenging activities of antioxidants. Furthermore, the results correlated with the (OH)-O-center dot-scavenging rate constants of the reagents evaluated by a "cupric ion reducing antioxidant capacity (CUPRAC)" assay. We applied the present method to estimate the (OH)-O-center dot-scavenging abilities of commercially available alcoholic drinks.
en-copyright= kn-copyright= en-aut-name=KomagoeKeiko en-aut-sei=Komagoe en-aut-mei=Keiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakeuchiHiroaki en-aut-sei=Takeuchi en-aut-mei=Hiroaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KatsuTakashi en-aut-sei=Katsu en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University en-keyword=Oxygen electrode kn-keyword=Oxygen electrode en-keyword=Oxygen consumption kn-keyword=Oxygen consumption en-keyword=Hydroxyl radical kn-keyword=Hydroxyl radical en-keyword=Hydroxyl radical-scavenger kn-keyword=Hydroxyl radical-scavenger en-keyword=Antioxidant kn-keyword=Antioxidant en-keyword=Alcoholic drink kn-keyword=Alcoholic drink END start-ver=1.4 cd-journal=joma no-vol=387 cd-vols= no-issue=6 article-no= start-page=2057 end-page=2064 dt-received= dt-revised= dt-accepted= dt-pub-year=2007 dt-pub=200703 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=S,S,S-Tris(2-ethylhexyl) phosphorotrithioate as an effective solvent mediator for a mexiletine-sensitive membrane electrode en-subtitle= kn-subtitle= en-abstract= kn-abstract=S,S,S-Tris(2-ethylhexyl) phosphorotrithioate proved to be an effective solvent mediator for constructing a mexiletine-sensitive membrane electrode in combination with an ion-exchanger, sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate. Among a series of phosphorus compounds containing phosphoryl (P=O) groups, this solvent mediator showed the highest sensitivity to mexiletine in phosphate-buffered physiological saline containing 0.15 mol L-1 NaCl and 0.01 mol L-1 NaH2PO4/Na2HPO4 (pH 7.4), giving a detection limit of 2 x 10(-6) mol L-1 with a slope of 58.8 mV decade(-1). This is the best reported detection limit of any mexiletine-sensitive electrode developed to date. Owing to its high selectivity toward inorganic cations, the electrode was used to determine the level of mexiletine in saliva, the monitoring of which is quite effective for controlling the dose of this drug noninvasively. The mexiletine concentrations determined with the mexiletine-sensitive electrode compared favorably with those determined by high-performance liquid chromatography. en-copyright= kn-copyright= en-aut-name=KatsuTakashi en-aut-sei=Katsu en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TsunamotoYumi en-aut-sei=Tsunamoto en-aut-mei=Yumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HaniokaNobumitsu en-aut-sei=Hanioka en-aut-mei=Nobumitsu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KomagoeKeiko en-aut-sei=Komagoe en-aut-mei=Keiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MasudaKazufumi en-aut-sei=Masuda en-aut-mei=Kazufumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=NarimatsuShizuo en-aut-sei=Narimatsu en-aut-mei=Shizuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=5 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=6 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University en-keyword=Ion-selective electrode kn-keyword=Ion-selective electrode en-keyword=Mexiletine determination kn-keyword=Mexiletine determination en-keyword=S,S,S-Tris(2-ethylhexyl) phosphorotrithioate kn-keyword=S,S,S-Tris(2-ethylhexyl) phosphorotrithioate en-keyword=Solvent mediator kn-keyword=Solvent mediator en-keyword=Drug monitoring kn-keyword=Drug monitoring END start-ver=1.4 cd-journal=joma no-vol=620 cd-vols= no-issue=1-2 article-no= start-page=50 end-page=54 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=20080714 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=A caffeine-sensitive membrane electrode: Previous misleading report and present approach en-subtitle= kn-subtitle= en-abstract= kn-abstract=Although a previous study [S.S.M. Hassan, M.A. Ahmed, M.M. Saoudi, Anal. Chem. 57 (1985) 1126] had shown that a caffeine-sensitive electrode made with picrylsulfonate and 1-octanol as a cation-exchanger and a solvent mediator, respectively, had a wide working pH range (5.5-9.5) and exhibited a Nernstian response, we could not find such response in this electrode. The present result was reasonable, because the pK, value of caffeinium ion was reported to be around 0.7 and the neutral form of caffeine was predominant in the pH range examined. Thus, we reinvestigated the response characteristics of a caffeine electrode, taking into consideration the pKa value, and constructed a new electrode with a combination of the lipophilic cation-exchanger, tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate (HFPB), and the solvent mediator with high degree of dielectric constant, 2-fluoro-2'-nitrodiphenyl ether (FNDPE). This electrode showed a pH-dependent response to caffeinium ion and gave a detection limit of 50 mu M with a slope of 55 mV per concentration decade at pH 2. The use of other solvent mediators was less effective than that of FNDPE. The electrode was applied for the determination of caffeine in some central stimulants. en-copyright= kn-copyright= en-aut-name=KatsuTakashi en-aut-sei=Katsu en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TsunamotoYumi en-aut-sei=Tsunamoto en-aut-mei=Yumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HaniokaNobumitsu en-aut-sei=Hanioka en-aut-mei=Nobumitsu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KomagoeKeiko en-aut-sei=Komagoe en-aut-mei=Keiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MasudaKazufumi en-aut-sei=Masuda en-aut-mei=Kazufumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=NarimatsuShizuo en-aut-sei=Narimatsu en-aut-mei=Shizuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=5 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=6 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University en-keyword=ion-selective electrode kn-keyword=ion-selective electrode en-keyword=caffeinium ion kn-keyword=caffeinium ion en-keyword=solvent mediator kn-keyword=solvent mediator en-keyword=2-fluoro-2 '-nitrodiphenyl ether kn-keyword=2-fluoro-2 '-nitrodiphenyl ether en-keyword=caffeine determination kn-keyword=caffeine determination END start-ver=1.4 cd-journal=joma no-vol=1808 cd-vols= no-issue=1 article-no= start-page=490 end-page=497 dt-received= dt-revised= dt-accepted= dt-pub-year=2011 dt-pub=201101 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comparative study of the membrane-permeabilizing activities of mastoparans and related histamine-releasing agents in bacteria, erythrocytes, and mast cells en-subtitle= kn-subtitle= en-abstract= kn-abstract=The membrane-permeabilizing activities of mastoparans and related histamine-releasing agents were compared through measurements of K(+) efflux from bacteria, erythrocytes, and mast cells. Changes in bacterial cell viability, hemolysis, and histamine release, as well as in the shape of erythrocytes were also investigated. The compounds tested were mastoparans (HR1, a mastoparan from Polistes jadwagae, and a mastoparan from Vespula lewisii), granuliberin R, mast cell-degranulating peptide, and compound 48/80, as well as antimicrobial peptides, such as magainin I, magainin II, gramicidin S. and melittin. We used a K(+)-selective electrode to determine changes in the permeability to K(+) of the cytoplasmic membranes of cells. Consistent with the surface of mast cells becoming negatively charged during histamine release, due to the translocation of phosphatidylserine to the outer leaflet of the cytoplasmic membrane, histamine-releasing agents induced K(+) efflux from mast cells, dependent on their ability to increase the permeability of bacterial cytoplasmic membranes rich in negatively charged phospholipids. The present results demonstrated that amphiphilic peptides, possessing both histamine-releasing and antimicrobial capabilities, induced the permeabilization of the cytoplasmic membranes of not only bacteria but mast cells. Mastoparans increased the permeability of membranes in human erythrocytes at higher concentrations, and changed the normal discoid shape to a crenated form. The structural requirement for making the crenated form was determined using compound 48/80 and its constituents (monomer, dimer, and trimer), changing systematically the number of cationic charges of the molecules. en-copyright= kn-copyright= en-aut-name=NakaoSatoshi en-aut-sei=Nakao en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KomagoeKeiko en-aut-sei=Komagoe en-aut-mei=Keiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=InoueTsuyoshi en-aut-sei=Inoue en-aut-mei=Tsuyoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KatsuTakashi en-aut-sei=Katsu en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University en-keyword=Mastoparan kn-keyword=Mastoparan en-keyword=Compound 48/80 kn-keyword=Compound 48/80 en-keyword=Antimicrobial peptide kn-keyword=Antimicrobial peptide en-keyword=Histamine-releasing agent kn-keyword=Histamine-releasing agent en-keyword=Membrane permeability kn-keyword=Membrane permeability en-keyword=Cell shape kn-keyword=Cell shape END