PubMed Health⌕ Search

Biomedical subjects

I Ueda

Publications and source records attributed to I Ueda.

At least 37 records · Page 2Linked to original sources
PubMed1990

Proton flow along lipid bilayer surfaces: effect of halothane on the lateral surface conductance and membrane hydration.

Impedance dispersion in liposomes measures the lateral charge transfer of lipid membrane surfaces. Depending on the choice of frequency between 1 kHz and 100 GHz, relaxation of the counterions at the interface, orientation of the head group, and relaxation of the bound and free water are revealed. This study measured the impedance dispersion in dipalmitoylphosphatidylcholine (DPPC) liposomes at 10 kHz. The surface conductance and capacitance showed breaks at pre- and main transition temperatures. Below the pre-transition temperature, the activation energy of the ion movement was 18.1 kJ.mol-1, which corresponded to that of the spin-lattice relaxation time of water (18.0 kJ.mol-1). At temperatures between pre- and main transition it increased to 51.3 kJ.mol-1, and agreed with 46.2-58.0 kJ.mol-1 of the activation energy of the dielectric relaxation of ice. Because the present system was salt-free, the ions were H3O+ and OH-, hence, their behavior represents that of water. The above results show that below the pre-transition temperature, the conductance is regulated by the mobility of free ions, or the number of free water molecules near the interface. On the other hand when the temperature exceeded pre-transition, melting of the surface-bound water crystals became the rate-limiting step for the proton flow. Halothane did not show any effect on the ion movement when the temperature was below pre-transition. When the temperature exceeded pre-transition, 0.35 mM halothane (equilibrium concentration) decreased the activation energy of the ion movement to 29.3 kJ.mol-1. This decrease indicates that halothane enhanced the release of the surface-bound water molecules at pre-transition. The surface-disordering effect of halothane was also shown by depression of the pre-transition temperature and decrease of the association energy among head groups from 9.7 kJ.mol-1 of the control to 5.2 kJ.mol-1 at 0.35 mM.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

Anesthesia cutoff phenomenon: interfacial hydrogen bonding.

Anesthesia "cutoff" refers to the phenomenon of loss of anesthetic potency in a homologous series of alkanes and their derivatives when their sizes become too large. In this study, hydrogen bonding of 1-alkanol series (ethanol to eicosanol) to dipalmitoyl-L-alpha-phosphatidylcholine (DPPC) was studied by Fourier transform infrared spectroscopy (FTIR) in DPPC-D2O-in-CCl4 reversed micelles. The alkanols formed hydrogen bonds with the phosphate moiety of DPPC and released the DPPC-bound deuterated water, evidenced by increases in the bound O-H stretching signal of the alkanol-DPPC complex and also in the free O-D stretching band of unbound D2O. These effects increased according to the elongation of the carbon chain of 1-alkanols from ethanol (C2) to 1-decanol (C10), but suddenly almost disappeared at 1-tetradecanol (C14). Anesthetic potencies of these alkanols, estimated by the activity of brine shrimps, were linearly related to hydrogen bond-breaking activities below C10 and agreed with the FTIR data in the cutoff at C10.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

Spontaneous oscillation of artificial membrane: equivalence in effects of temperature and volatile anesthetic.

Oscillatory phenomenon at an oil-water interface in the presence of hexadecyltrimethylammonium bromide (CTAB) has been studied. The oscillation was attributable to successive formation and destruction of surfactant monolayer. According to the temperature elevation, the frequency of the electrical oscillation increased whereas the amplitude decreased. Addition of diethylether increased the frequency and decreased the amplitude. These effects of temperature and anesthetic were analyzed by the theory of the "N"-shaped relationship between surface-pressure and surface-concentration of the surfactant.

Cetrimonium↗
PubMed1990

Infrared spectra of phospholipid membranes: interfacial dehydration by volatile anesthetics and phase transition.

Fourier-transform infrared attenuated total reflection (ATR) spectroscopy was used to study the effect of volatile anesthetics on fully hydrated dipalmitoylphosphatidylcholine (DPPC) vesicle membranes. The main phase transition was monitored by the change in the C-H2 asymmetric stretching frequencies of the lipid tails. The surface property was analyzed by the changes in the P = O stretching, (CH3)3-N+ stretching of the hydrophilic head, and C = O stretching of the glycerol skeleton. The partial pressures of those agents that decreased the transition temperature 1.0 C degree were halothane 0.75, enflurane 1.90 and CCl4 0.85 kPa. At a 2:1 lipid/anesthetic mole ratio, the polar anesthetics, halothane and enflurane, increased the ratio of (P = O stretching band area)/((CH3)3-N+ stretching band area) by 26.3% and 21.1%, respectively, whereas apolar CCl4 increased it 10.5%. The water molecules bound to the P = O moiety are apparently replaced by the anesthetic molecules. The deconvoluted C = O spectra showed two peaks: free sn-1 that is closer to the lipid core and hydrogen-bonded sn-2 that is closer to the polar head. Addition of halothane and enflurane, but not CCl4, increased the number of peaks to three. The third peak is free sn-2, formed by disrupting hydrogen-bonding to water. Because the temperature-induced spectral change was limited to C-H2 stretching at the main phase transition, the effects of anesthetics on the lipid membrane structure are not identical to temperature elevation. Among anesthetics, the effects of apolar and polar molecules on the interfacial properties are different.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

Use of ion-exchange membranes to measure transfer free energies of charged local anesthetics: correlation to anesthetic potency.

Ion-selective electrodes, sensitive to local anesthetic cations, were prepared with carboxylated poly(vinyl chloride) (PVC) membranes. Three plasticizers with varying degrees of polarity were used to adjust the hydrophobicity of the membrane. The affinity of the drug to the ion-exchange membrane was measured by the electromotive force of the cation-selective electrodes. The difference in the transfer free energies of the anesthetics for the membrane was estimated in reference to dibucaine. The values correlated to their clinical potencies. By comparing drugs with similar structures, the transfer free energy per methylene moiety linked to the hydrophilic domain was found to be -1.7 kJ.mol-1, and that of Cl linked to the hydrophobic domain was -3.1 kJ.mol-1. Interferences from Na+ and K+ were estimated as the selectivity coefficients against dibucaine. The values were 2.6 x 10(-5) for Na+ and 1.2 x 10(-4) for K+. The ion-exchange membrane appears to mimic the surface properties of cell membranes. These cation-selective electrodes have potential applicability in measuring charged local anesthetic concentrations (activities) in biological materials under limited conditions.

Anesthetics↗
PubMed1990

Adsorption of local anesthetics on activated carbon: Freundlich adsorption isotherms.

We have shown that adsorbability of local anesthetics onto activated carbon, expressed by the partition coefficients at infinite dilution, correlated well with the pharmacological activity. However, there is no parameter that can singly express the tendency to be adsorbed. Adsorbability is a loosely defined term and its meaning varies with the adsorption model. This study showed that the logarithm of the adsorbed amount of drugs was linearly related to the logarithm of the free drug concentration, in conformity to the Freundlich adsorption isotherms. The slope of the double logarithmic plot is expressed by 1/N in the Freundlich equation and is considered to be inversely related to the drug affinity to the adsorbent. The slope was used to evaluate the tendency to be adsorbed, or "adsorbability" of seven aromatic amine local anesthetics. Phenobarbital was included to compare anionic drugs in contrast to the cationic local anesthetics. The slopes were nearly equal between the cationic and neutral local anesthetics. Apparently, the lower hydrophobicity of the cationic forms is compensated by the electrostatic attraction from the negative charges present on the activated carbon surface. With phenobarbital, the slope value of the anionic form was larger than the neutral form. The lower affinity of the anionic form may be caused by the electrostatic repulsion. The molecular size parameters (i.e., molecular weight, molar refraction, and parachor) showed a linear relationship to the slope values. It may be possible to estimate the affinity-related slope values from these parameters.

Adsorption↗
PubMed1990

High pressure and anesthesia: compressibility, molal volume, and partial molal volume of volatile anesthetics.

This study was undertaken to provide volume data of volatile anesthetics under high pressure. Molal volumes of liquid halothane, enflurane, and isoflurane and their partial molal volumes in water and in 1-octanol were determined by high-precision solution densitometry at 25.000 +/- 0.0005 degrees C over the pressure range from ambient to 34.56 MPa (341 atm). The isothermal compressibilities of the pure anesthetics and their isothermal partial molal compressibilities at their infinite dilution in water and in 1-octanol have also been calculated at 0.1013 MPa (1 atm).

1-Octanol↗
PubMed1990

Synthesis and pharmacological properties of N-[3-(3-(1-Piperidinylmethyl)phenoxy)propyl]-2-(2-hydroxyethylthio)- acetamide and related compounds as antiulcer agents. I.

N-Phenoxypropylacetamide derivatives were prepared and tested for antiulcer activity. These compounds exhibited both gastric acid antisecretory and cytoprotective properties. Structure-activity studies led to the identification of N-[3-(3-(1-piperidinylmethyl)phenoxy)propyl]-2-(2-hydroxyethylt hio)acetamide (8), which was selected for further development and clinical evaluation.

Animals↗
PubMed1989

Differential affinity of charged local anesthetics to solid-gel and liquid-crystalline states of dimyristoylphosphatidic acid vesicle membranes.

Cationic local anesthetics decreased the transition temperature of the anionic phospholipid (dimyristoylphosphatidic acid, DMPA) vesicles. The counterion concentration changes the electrical double layer effect, and affects the magnitude of temperature depression caused by anesthetics. From the counterion effect on the transition-temperature depression, the partition coefficients of cationic local anesthetics to liquid-crystalline and solid-gel DMPA membranes were separately estimated. The differences in the partition coefficients between solid-gel and liquid-crystalline membranes correlated to the nerve blocking potencies. There are at least two states in the nerve membranes: resting state at higher temperature and excited state at lower temperature. We speculate that the resting state corresponds to the liquid-crystalline state, and the excited state to the solid-gel state. The difference in the partition coefficients to the resting and excited states is the cause of local anesthesia.

Anesthetics, Local↗
PubMed1989

Molecular orientation of volatile anesthetics at the binding surface: 1H- and 19F-NMR studies of submolecular affinity.

The shift of 1H- and 19F-NMR peaks in the frequency domain was used to resolve the solubilization of volatile anesthetics into sodium dodecylsulfate micelles to submolecular level. Enflurane has protons at both ends of the molecule, and the solubilization parameters (partition coefficients in a broad sense) of each end were estimated by 1H-NMR. The values were: 2130 for the hydrophobic end and 1980 for the hydrophilic end. The hydrophobic end of halothane is CF3, hence 19F-NMR was used: 4330 for the hydrophobic end and 2670 for the hydrophilic end. The ratios of the solubilization parameters between hydrophobic and hydrophilic ends were methoxyflurane 1.9 (Kaneshina et al. (1981) Biochim. Biophys. Acta 647, 223-226), enflurane 1.1, and halothane 1.6. The results indicate that methoxyflurane and halothane adsorb perpendicular to the membrane surface, whereas enflurane molecules stay parallel to the interface. The averaged solubilization parameters of both ends of these anesthetics were in good agreement with their conventional partition coefficients between dipalmitoylphosphatidylcholine (DPPC) membranes and water. The solubilization parameter of chloroform (1H-NMR) was 1580 in agreement with the reported values of DPPC-water partition coefficient.

Anesthetics↗
PubMed1989

Changes in surface capacitance and conductance parallel to phospholipid membranes associated with phase transition: effects of halothane.

The effects of phase transition on the surface capacitance and conductance parallel to dipalmitoyl- (DPPC) and dimyristoyl-phosphatidylcholine (DMPC) membranes were studied by impedance dispersion. The phospholipid aggregates were embedded into pores of a polycarbonate filter and the impedance dispersions were measured at a frequency range from 30 Hz to 1.0 MHz. When the frequency was below 120 kHz, the capacitance showed a peak at the pretransition temperature and a steep rise at the main-transition temperature. In this system, the observed capacitance consists of frequency-dependent and -independent parts. The frequency-dependent part is a surface phenomenon and arises from the lateral motion of counterions at the membrane/water interface. The frequency-independent part represents mainly the properties of the bulk lipid phase. Addition of halothane decreased the total capacitance of the DPPC aggregates at the low frequency range to 1/2 to 1/8 of the control depending upon the temperature. The surface component was solely responsible for this capacitance decrease, because the non-surface component was slightly increased instead. The data suggest that halothane inhibited the lateral ionic flow parallel to the interface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

400 MHz two-dimensional nuclear Overhauser spectroscopy on anesthetic interaction with lipid bilayer.

Interaction between a volatile anesthetic, methoxyflurane, and dipalmitoylphosphatidylcholine (DPPC) vesicle membrane was analyzed by nuclear Overhauser effect (NOE) difference spectroscopy and two-dimensional nuclear Overhauser spectroscopy (NOESY). The NOE difference spectra were obtained by selectively irradiating methoxy protons (hydrophobic end) of the anesthetic: a negative nuclear Overhauser effect of -2.94% was observed with the choline methyl protons of DPPC. The NOESY spectra revealed a cross-peak between the anesthetic methoxy protons and the choline methyl protons. A dipole-dipole interaction exists between the hydrophobic end of the anesthetic and the hydrophilic head group of DPPC. No other cross-peaks were observed. The anesthetic orients itself at the membrane/water interface by interacting with the hydrophilic surface of the DPPC membrane, leaving the hydrophilic end of the anesthetic molecule in the aqueous phase. The preferred residence site of dipolar volatile anesthetics is the membrane/water interface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Saturable and unsaturable binding of a volatile anesthetic enflurane with model lipid vesicle membranes.

Presence of specific receptors for volatile anesthetics has recently been proposed (Evers, A.S. et al. (1987) Nature 328, 157-160) by a finding that halothane uptake by the rat brain was characterized, in part, by saturable binding. We report here that volatile anesthetics bind model lipid membranes also with saturable and unsaturable kinetics. Binding of enflurane to dipalmitoylphosphatidylcholine vesicle membranes was measured by gas chromatography. At low anesthetic concentrations, comparable to the clinical level, the interaction was saturable. After reaching a temporary saturation, a sudden increase in the anesthetic binding to the membrane occurred, when the anesthetic concentration in the aqueous phase exceeded 2.7 mM, or 6.3 x 10(-2) atm partial pressure in the gas phase in equilibrium with the aqueous phase. The secondary binding was linear to the aqueous anesthetic concentrations and was unsaturable to the limit of this study. We also found that enflurane self-aggregated in water above 4 mM. When the aqueous concentration exceeded 6 mM, the aggregation number was about 8. We conclude that the saturable binding indicates adsorption onto the vesicle surface, and the unsaturable binding indicates multilayer stacking of the enflurane molecules, where the initially adsorbed molecules provide the binding sites to the succeeding molecules according to the multilayer condensation kinetics. The tendency of enflurane to self-aggregate in water promotes the multilayer stacking at the surface of the membrane.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Application of Namalva interferon-alpha monoclonal antibodies for purification and enzyme immunoassay of interferon-alpha.

Namalva (or Namalwa) interferon (IFN)-alpha was partially purified using a combination of conventional methods and modified acid-ethanol extraction. Four mouse monoclonal antibodies against Namalva IFN-alpha were prepared by hybridoma technology after immunization with Namalva IFN-alpha thus purified. Three of these monoclonal antibodies recognized the same or a similar epitope on Namalva IFN-alpha. One of these antibodies was paired with the fourth recognizing a different epitope and used respectively as enzyme-conjugated antibody and solid-phase antibody in our one step enzyme immunoassay (EIA) for IFN-alpha. This assay is simple and was able to detect as little as 5 pg of IFN-alpha in 100 microliters of sample in the short time of 5 hr. There was a good correlation between the EIA and bioassay. The use of one of the monoclonal antibodies as an immunoadsorbant to purify Namalva IFN-alpha is also described.

Animals↗
PubMed1989

[Dental caries of primary teeth and life habits in Shinshinotsu Nursery School: three years of observations].

It is well known that there is a high positive correlation between increases in caries increment and life habits such as use of nursing bottle, tooth brushing, between-meal eating, and sweet consumption. The purpose of this study was to analyze data of caries status in primary dentition and life habits observed in 373 Shinshinotsu nursery schoolchildren aged 3-5 years over three years. Dental examinations were conducted in good natural light using dental mirror and probe. Caries was diagnosed according to the Welfare Ministry criteria and life habits were examined by a questionnaire. The mean number of df was 7.1 for the whole sample for three years and 17.6 of the children were caries free, whereas 47.3 were more than 10 df. The former group showed the best score for the frequency of between-meal eating, frequency of sweet consumption, tooth brushing habits, and frequency of fluoride application. The latter group showed a tendency to lower sweet consumption during the three years. Our data also showed that the life habits at nursing (use of nursing bottle and weaning period) influenced incidence of caries.

Child, Preschool↗
PubMed1989

[Dental caries of deciduous teeth in nursery school children in Shinshinotsu: changes in prevalence data for three years from 1986 to 1988].

The purpose of this study was to survey the changes in dental caries prevalence in 3-, 4-, and 5-year-old nursery school children in Shinshinotsu for 3 years from 1986 to 1988. The results obtained were as follows: 1) The caries prevalence in 5-year-old Shinshinotsu children decreased from 1986, and was 87.5% in 1988, lower than the national survey in 1987. On the other hand, the number of df teeth per person and the incidence of type C caries increased in 5-year-old Shinshinotsu children. 2) The caries prevalence rate in 3-year-old Shinshinotsu children was 89.5% in 1988, rather higher than the national survey in 1987.

Child, Preschool↗
PubMed1989

Smooth muscle contraction and local anesthetics: calmodulin-dependent myosin light-chain kinase.

Myocardial depressant action of local anesthetics at toxic concentrations is well documented. Their effect on vascular smooth muscle, however, remains controversial. This study analyzed local anesthetic action on the subcellular smooth-muscle contractile system. Highly purified smooth-muscle myosin and myosin light-chain kinase (MLCK) were prepared from fresh turkey gizzards, and the phosphorylation of the myosin light-chain in the presence of Ca++ and calmodulin was evaluated by the urea gel-electrophoresis. Tetracaine 1.3.10(-3) M and bupivacaine 7.5.10(-3) M inhibited the MLCK 50%, whereas lidocaine 2.5.10(-2) M inhibited the MLCK 40%. The inhibitory action was partially reversed by increasing the calcium ion concentration from 1.10(-5) to 2.10(-4) M. On the other hand, raising the calmodulin concentration from 1.10(-7) M to 6.10(-7) M completely reversed the inhibition. A possible cause of the discrepancy in the anesthetic concentrations between subcellular and in vivo studies is discussed.

Bupivacaine↗