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Biomedical subjects

I Ueda

Publications and source records attributed to I Ueda.

At least 163 records · Page 9Linked to original sources
PubMed1982

Interfacial adsorption of an inhalation anesthetic onto ionic surfactant micelles and its desorption by high pressure.

The effects of pressure and temperature on the critical micelle concentration (CMC) of sodium dodecylsulfate (SDS) wer measured in the presence of various concentrations of an inhalation anesthetic, methoxyflurane. The change in the partial molal volume of SDS on micellization delta Vm, increased with the increase in the concentration of methoxyflurane. The CMC-decreasing power, which is defined as the slope of the linear plot between In(CMC) vs. mole fraction of anesthetic, was determined as a function of pressure and temperature. Since the CMC-decreasing power is correlated to the micelle/water partition coefficient of anesthetic, the volume change of the transfer (delta Vop) of methoxyflurane from water to the micelle can be determined from the pressure dependence of the CMC-decreasing power. The value of delta Vop amounts 6.5 +/- 1.8 cm3.mol-1, which is in reasonable agreement with the volume change determined directly from the density data, 5.5+/-0.6 cm3.mol-1. Under the convention of thermodynamics, this indicates that the application of pressure squeezes out anesthetic molecules from the micelle. The transfer enthalpy of anesthetic from water to the micelle is slightly endothermic. The partial molal volume of methoxyflurane in the micelle (112.0 cm3.mol-1) is smaller than that in decane (120.5 cm3.mol-1) and is larger than that in water (108.0 cm3. mol-1. This indicates that the anesthetic molecules are incorporated into the micellar surfaces region, i.e., the palisade layer of the micelle in contact with water molecules, rather than into the micelle core.

Anesthesia, Inhalation↗
PubMed1982

Effect of L-leucine-supplemented diet on the nicotinamide adenine dinucleotide content of rat liver.

The hepatic nicotinamide adenine dinucleotide (NAD) content was significantly lower in rats fed a diet supplemented with 0.45-10% L-leucine for 1-3 weeks than in control rats fed laboratory chow (24.6% protein). High dietary levels of leucine did not affect the activity of hepatic tryptophan pyrrolase or quinolinate phosphoribosyltransferase, which are key enzymes in the tryptophan leads to NAD pathway. The increased hepatic NAD contents 4 hours after intraperitoneal injections of the NAD precursors L-tryptophan, niacin and nicotinamide were not influenced by excess dietary leucine. These observations suggest that decrease in the hepatic NAD content by excess dietary leucine is not due to alteration of NAD metabolism resulting from accumulation of leucine or its metabolite. The uptake of 1 mM L-[side chain-2,3-3H]tryptophan into isolated jejunal segments was inhibited markedly by 10 mM-leucine. Similar inhibitory effects were observed with 10 mM L-valine, L-isoleucine, L-phenylalanine and L-methionine, but not-L-lysine, L-aspartate, L-alanine or glycine. The radioactivity in portal blood after administration of a solution of 10 mumol of L-[side chain-3-14C]tryptophan in 1 ml of physiological saline by stomach tube was inhibited markedly by addition to the solution of 100 mumol of L-leucine or the other amino acids that inhibited L-tryptophan uptake by isolated jejunal segments. These findings strongly suggest that decrease in the liver NAD content by excess dietary leucine is mainly due to competitive inhibition by L-leucine of intestinal absorption of L-tryptophan.

Animals↗
PubMed1982

Anesthetics expand partial molal volume of lipid-free protein dissolved in water: electrostriction hypothesis.

The present study was undertaken to critically examine whether the dilating action of inhalation anesthetics is specific to lipid membranes. Delipidated crystalline bovine serum albumin was used as a model and the density of a salt-free aqueous solution was measured by a high-precision oscillation densimeter. The partial molal volumes of albumin at infinite dilution were 50,326, 51,019 and 51,698 cm3 . mol-1, respectively at 293, 308 and 323 degrees K. From the difference between the present value and the volume of dry albumin, the number of electrostricted water molecules at the surface of albumin in aqueous solution at 293.15 degrees K is estimated to be about 720. Addition of diethylether to the albumin solution increased the partial molal volume of albumin, dose-dependently. At 57.88 mmolal, diethylether expanded the partial molal volume of albumin at 293 degrees K by 295 cm3 . mol-1 or 0.59%. This volume expansion does not include the space occupied by the anesthetic molecules in albumin. If the expansion can be assumed to be caused mainly by melting of electrostricted water molecules, about 110 water molecules were released from the protein surface. The partial molal volume of diethylether was increased when bound to albumin. The increase indicates that the contact between diethylether and water is partially destroyed and that high pressure squeezes out anesthetic molecules from the protein.

Anesthetics↗
PubMed1981

The effect of pyrazines on the metabolism of tryptophan and nicotinamide adenine dinucleotide in the rat. Evidence of the formation of a potent inhibitor of aminocarboxy-muconate-semialdehyde decarboxylase from pyrazinamide.

The intraperitoneal or oral administration of pyrazinamide and pyrazinoic acid (pyrazine 2-carboxylic acid) resulted in a marked increase of the NAD content in rat liver. The injections of pyrazine and pyrazine 2,3-dicarboxylic acid exhibited no significant effect on the hepatic NAD content. The boiled extract obtained from liver and kidney of rat injected with either pyrazinamide or pyrazinoic acid exhibited a potent inhibitory effect on the aminocarboxymuconate-semialdehyde decarboxylase (EC 4.1.1.45) activity in either lier or kidney, although pyrazinamide or pyrazinoic acid per se did not inhibit the enzyme activity. The unknown inhibitor of aminocarboxymuconate-semialdehyde decarboxylase was dialysable and heat-stable, and mostly excreted in urine by 6 and 12 h after injected of pyrazinoic acid and pyrazinamide, respectively. Pyrazine 2,3-dicarboxylic acid, pyrazine, nicotinamide, nicotinic acid, tryptophan, anthranilic acid, 5-hydroxyanthranilic acid and quinolinic acid exhibited no significant effect on the aminocarboxymuconate-semialdehyde decarboxylase activity in liver and kidney at the concentration of 1 mM in the reaction mixture. The expired 14CO2 from L-[benzen ring-U-14C]tryptophan was markedly decreased by the pyrazinamide injection, while the urinary excretion of 14C-labeled metabolites from L-tryptophan, mainly quinolinic acid, was markedly increased. These results suggest that the glutarate pathway of L-tryptophan was strongly inhibited by the inhibitor produced after the administration of pyrazinoic acid and pyrazinamide. Pyrazinamide but not pyrazinoic acid also exhibited a significant inhibition of the nuclear enzyme poly(ADP-ribose) synthetase in rat liver.

Animals↗