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Biomedical subjects

H Terada

Publications and source records attributed to H Terada.

At least 289 records · Page 16Linked to original sources
PubMed1986

Binding of cobalamin analogs to intrinsic factor-cobalamin receptor and its prevention by R binder.

It is now known that nonphysiological cobalamin analogs exist in the gastrointestinal tract, but their metabolic behavior is unclear. In this study, [57Co]cobinamide was used to study its affinity to hog intrinsic factor-cobalamin (IF-Cbl) receptor which has no species specificity against human IF-Cbl receptor, and its relation to human saliva R binder. Cobinamide was prepared from [57Co]cyanocobalamin and separated by paper chromatography. Human IF-Cbl complex was bound to IF-Cbl receptor but free cyanocobalamin was not. Although R binder-cobinamide was not bound to the IF-Cbl receptor, free cobinamide was bound to the IF-Cbl receptor to a significant extent (about one-half of IF-cyanocobalamin binding to the IF-Cbl receptor). We then investigated the binding of cobinamide to R binder and trypsin-treated R binder. Association constant of cobinamide binding to the IF-Cbl receptor was 1.0 X 10(9) M-1 which was much lower than that of cobinamide binding to trypsin-treated R binder and to untreated R binder. Further study indicated that cobinamide binding to the IF-Cbl receptor was blocked by the addition of R binder and also by trypsin-treated R binder. We conclude that one of the roles of R binder is to prevent binding of free cobalamin analogs to the IF-Cbl receptor in the gut.

Cobamides↗
PubMed1985

Studies on residual antibacterials in foods. IV. Simultaneous determination of penicillin G, penicillin V and ampicillin in milk by high-performance liquid chromatography.

A rapid and simple method for the simultaneous determination of penicillin G (PCG), penicillin V (PCV) and ampicillin (ABPC) in milk is described. The retention behaviour of these beta-lactam antibiotics in reversed-phase liquid chromatography with mobile phases containing sodium alkylsulphonate was studied. Good separations were obtained with methanol-water-0.2 M phosphate buffer (pH 4.0) (5:13:2) containing 11 mM sodium 1-heptanesulphonate and a LiChrosorb RP-18 column. The sample was pre-treated with a Sep-Pak C18 cartridge. The peaks corresponding to each beta-lactam antibiotics can be confirmed with the treatment using penicillinase. The recoveries from milk fortified with sodium PCG, potassium PCV and ABCP at levels of 0.5 and 0.1 micrograms/g each were generally better than 87% and the relative standard deviations were 1.17-4.98%. The detection limits corresponded to 0.03 microgram/g of these beta-lactam antibiotics in milk.

Ampicillin↗
PubMed1985

Studies on the analysis of food additives by high-performance liquid chromatography. V. Simultaneous determination of preservatives and saccharin in foods by ion-pair chromatography.

A high-performance liquid chromatographic method for the simultaneous determination of sorbic acid, benzoic acid, p-hydroxybenzoic acid and its methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl esters and saccharin in foodstuffs is described. For good separations of these compounds, acetonitrile-water-0.2 M phosphate buffer pH 3.6 (7:12:1) containing 2 mM cetyltrimethylammonium bromide as an ion-pair reagent and a Nucleosil 5C18 column are required. A steam distillation method and a Sep-Pak C18 cartridge method for the sample preparation are compared. The recoveries from a coffee drink were generally better than 93.8% and the relative standard deviations were 0.85-2.15% for the Sep-Pak C18 cartridge method.

Beverages↗
PubMed1985

Formation of a leakage-type ion pathway in lipid bilayer membranes by divalent cationic cyanine dyes in cooperation with inorganic phosphate. Role of the cyanine dye in uncoupling of oxidative phosphorylation.

Divalent cationic cyanine dyes, such as 2,2'-[3-[2-(3-butyl-4-methyl-2-thiazoline-2-ylidene)-ethylidene] propenylene]bis[3-butyl-4-methylthiazolinium iodide] and platonin induced large membrane current fluctuation when an electrical potential difference was applied across a planar phosphatidylserine bilayer membrane in medium containing inorganic phosphate (Pi). Without Pi, the dyes did not induce current fluctuation at concentrations of less than 30 microM. Noise analysis of current fluctuation indicated formation of a pathway for ion leakage. From measurements of the interfacial tension between oil and aqueous phases, and of water permeability across liposomal membranes, Pi was concluded to relax the phospholipid bilayer structure, resulting in great reduction in the concentration of the cyanine dye necessary for induction of the leakage-type pathway. In the presence of Pi, cationic ions such as tetrabutyl ammonium and tetraphenyl phosphonium did not induce the leakage-type pathway, although they had electrophoretic effects at high concentrations. These facts suggest that the mechanism of the uncoupling of oxidative phosphorylation by dicationic cyanine dyes in mitochondria is different from that of cationic uncouplers such as tetrabutyl ammonium ion.

Cations, Divalent↗
PubMed1985

Specific and non-specific ligand binding to serum albumin.

The applicability of a model of specific and non-specific binding sites for the binding of organic ligands to serum albumin was examined statistically. It is proposed in this model that there are a limited number of a single class of high affinity sites and an unlimited number of low affinity sites. Ligands bind to the former sites independently, as in the Scatchard model for a single class of binding sites, and to the latter sites in a partition-like manner, the amounts bound increasing linearly with the concentration of free ligands. In this study, data on the binding of warfarin to human serum albumin reported by Wilting et al. [J. Wilting et al., J. biol. Chem. 255, 3032 (1980)] and on the bindings of indomethacin and salicylic acid to human serum albumin reported by Hultmark et al. [D. Hultmark et al., Acta pharm. suecica 12, 259 (1975)] were used. These binding data were analyzed according to the model of specific and non-specific sites as well as the Scatchard model of two classes of binding sites. Statistical analyses showed that the model of specific and non-specific binding sites fitted the data for binding of all compounds very well, indicating the applicability of this model. An index of the upper limit of ligand concentrations necessary for accurate analysis of the binding data was also discussed.

Binding Sites↗
PubMed1985

Uncoupling of oxidative phosphorylation by divalent cationic cyanine dye. Participation of phosphate transporter.

The trinuclear cationic cyanine dye tri-S-C4(5) was found to be an uncoupler of oxidative phosphorylation. Its uncoupling required inorganic phosphate (Pi) or arsenate, which is transported into mitochondria via the Pi transport system, and was abolished by the Pi-transport inhibitor N-ethylmaleimide or mersalyl. The dye stimulated Pi uptake into mitochondria, and its uncoupling action was accompanied by swelling of the mitochondria. The adenine nucleotides ADP and ATP protected mitochondria from uncoupling by the dye. The dye taken up by mitochondria was released into the incubation medium on induction of uncoupling. In the absence of Pi, the dye did not cause uncoupling, but its uptake was much greater than in the presence of Pi. The cyanine dye is suggested to induce uncoupling by acting on the membrane, rather than after its electrophoretic transfer into the mitochondria.

Adenine Nucleotides↗
PubMed1985

Studies on residual antibacterials in foods. III. High-performance liquid chromatographic determination of penicillin G in animal tissues using an on-line pre-column concentration and purification system.

A simple and reproducible method for the determination of residual penicillin G in edible animal tissues by high-performance liquid chromatography (HPLC) is described. The method consists in an off-line clean-up step using a basic aluminium oxide column and a Sep-Pak C18 cartridge and an on-line pre-column concentration and purification system. The procedure shows good sensitivity and precision. The recoveries from cattle liver, kidney and muscle fortified with 1 microgram/g of sodium penicillin G were 75.0-92.6% and the relative standard deviations were 2.35-4.06%. The detection limit corresponded to 0.05 micrograms/g of sodium penicillin G in animal tissues.

Animals↗
PubMed1985

Caffeine degradation and increased ochratoxin A production by toxigenic strains of Aspergillus ochraceus isolated from green coffee beans.

The growth and ochratoxin A production of Aspergillus ochraceus strains S-235-100 and IFM 0458, which were isolated from green coffee beans and glutinous rice, respectively, were examined in yeast extract-sucrose (YES) medium containing 0.1 to 1.0% caffeine. The mycelial growth and ochratoxin A formation of strain IFM 0458 was inhibited by caffeine at concentrations over 0.1%, and ochratoxin A was not produced at caffeine levels of 0.5% and 1.0%. Contrary to this, A. ochraceus strain S-235-100 produced a larger amount of ochratoxin A in the presence of 0.5% and 1.0% caffeine when grown on YES medium, reaching a maximum after 15 to 20 days of incubation. The formation of ochratoxin A by nine additional strains of A. ochraceus, three strains of A. elegans and one strain of A. sclerotiorum isolated from green coffee beans was determined on rice and ground green coffee media. A significant degree of degradation of caffeine in the green coffee medium was demonstrated with cultures of nine A. ochraceus isolates from green coffee beans. Most of these isolates showed the potential to grow on moist green coffee beans and to produce a significant amount of ochratoxins.

Aspergillus↗
PubMed1985

Quantitative determination by derivative spectrophotometry of Triton X-100 in solubilized preparations of membrane proteins.

The amount of the nonionic detergent Triton X-100 in protein preparations cannot be determined spectrophotometrically from the normal spectrum because the spectral bands of the detergent and proteins overlap, but it was found that the detergent could be determined accurately by 4th-derivative spectrophotometry. The intensity of the derivative absorbance difference between the positive and negative peaks at about 277.5 and 281 nm, respectively, increased linearly with increase in the detergent concentration at more than its critical micelle concentration (about 0.03%). Proteins had little effect on these spectral bands of the detergent. This method is very simple and accurate for determination of the concentration of Triton X-100 in solubilized preparations of membrane proteins.

Animals↗
PubMed1985

Effects of pantethine on action potential of canine papillary muscle during hypoxic perfusion.

Pantethine, which is known to be converted to coenzyme A, has been reported to have antiarrhythmic action on experimental cardiac arrhythmias. Using standard microelectrode techniques, the electrophysiological effects of pantethine under hypoxic (95% N2 + 5% CO2) perfusion were studied. Hypoxia decreased resting membrane potential, action potential amplitude and maximum velocity of phase 0 and shortened action potential duration and effective refractory period. Application of pantethine 5 X 10(-3) Gm/ml under hypoxic perfusion prolonged action potential duration and effective refractory period significantly. Prolongation of action potential duration by pantethine might be caused by an increase in intracellular ATP. The findings in this study could be an explanation of the possible antiarrhythmic effects of pantethine.

Action Potentials↗