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Biomedical subjects

B S Yu

Publications and source records attributed to B S Yu.

At least 19 recordsLinked to original sources
PubMed2001

Ion chromatographic determination of calcium and magnesium cations in human saliva and urine with a piezoelectric detector.

In this present paper, simultaneous determination of Ca(2+) and Mg(2+) cations in saliva, urine was achieved using an ion chromatography method, in which a piezoelectric quartz crystal (PQC) sensor was used as a detector, and a solution containing tartaric acid (4 mmol 1(-1)) and ethylenediamine (2 mmol 1(-1)) as a mobile phase. Good linearities were obtained over the ranges of 0.8-500 mg 1(-1) Ca(2+) and 1.0-500 mg 1(-1) Mg(2+). The detection limits were 0.4 mg 1(-1) for Ca and 0.2 mg 1(-1) for Mg, respectively.

Calcium↗
PubMed2001

Simultaneous determination of nitrate and nitrite in saliva and foodstuffs by non-suppressed ion chromatography with bulk acoustic wave detector.

In the present paper, nitrate and nitrite in foodstuffs and saliva were simultaneously determined using a non-suppressed ion chromatography (IC) method with a bulk acoustic wave sensor (BAW) as detector, and 1.5 mmol/L potassium hydrogenphthalate (KHP) as mobile phase. The IC-BAW method is simple, rapid and accurate. The determination limits for nitrite and nitrate are 0.20 and 0.30 mg/L, respectively. The IC-BAW is comparable and agrees with the conventional spectrophotometric method for nitrite and nitrate determination.

Chromatography, Ion Exchange↗
PubMed2000

Video assisted thoracoscopic ligation of patent ductus arteriosus. Technique of sliding loop ligation.

Variant video-assisted thoracoscopic surgical technique for closure of patent ductus arteriosus has been introduced. Although the endoscopic clipping device may be a preferred method for interruption of the patent ductus arteriosus, there is always the risk of inadequate clip placement and limitation of application in width of ductus arteriosus. In an effort to overcome this problem we have used a self-made endoscopic loop ligation in 10 patients and herein report the method. Only a small window and one port of access are necessary to dissect the patent ductus arteriosus from the surrounding tissues and to apply the extracorporeally created sliding loop. Successful ligation without shunt is obtained in all cases. The technique is simple and safe even in the presence of a wide ductus.

Child↗
PubMed1998

Inhibition of electric eel acetylcholinesterase by porphin compounds.

Synthetic porphin compounds have been found to be reversible inhibitors of acetylcholinesterase from electric eel with Ki values of microM range. It seems that the number and position of fluorine on the phenyl ring and metal of an inhibitor play an important role for binding of an inhibitor to the enzyme active site.

Acetylcholinesterase↗
PubMed1998

Flow-injection determination of total ammonia and total carbon dioxide in blood based on gas-diffusion separation and with a bulk acoustic wave impedance sensor.

A novel flow-injection (FIA) system, for the rapid and direct determination of both total ammonia (T[NH3]) and total carbon dioxide (T[CO2]) in clinical blood samples, has been developed. Samples were injected into a carrier stream of H2O, then emerged with a reagent stream, where the analyte was converted into a gaseous species and diffused across a PTFE gas-permeable membrane into an acceptor stream. The trapped NH3/CO2 in the acceptor was determined on line by a bulk acoustic wave (BAW) impedance sensor. At a through-put of 20 and 65 h(-1), the proposed system exhibited a linear frequency response up to 200 micromol l(-1) ammonium and 20 mmol l(-1) bicarbonate with a detection limit of 1.0 and 10 micromol l(-1), respectively. Results obtained for T(NH3) in serum and T(CO2) in plasma were in agreement with those obtained by the conventional glutamate dehydrogenase (GDH) method and gas-sensing electrode method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rate and potential interferents on the FIA signals were also discussed.

Acoustics↗
PubMed1997

Ion chromatographic study of sodium, potassium and ammonium in human body fluids with bulk acoustic wave detection.

In the present paper, determination of Na+, K+ and NH4+ in saliva and serum was carried out using an ion chromatography (IC) method with a bulk acoustic wave (BAW) sensor as detector and 2.0 mmol/l nitric acid as mobile phase. The IC-BAW method is simple, rapid and accurate. Comparison between the BAW detector and the conventional conductivity detector (CDD) was discussed. The IC-BAW showed agreement with the commonly used flame photometric method for Na+ and K+ and enzymatic method for NH4+, as well as IC-CDD for those three cations.

Body Fluids↗
PubMed1989

Dynamic properties of interaction between nucleic acid bases and models of amino acids.

We have discussed the possible hydrogen bonding mode of adenine-uracil base dimers and peptide side chains, together with their characteristic effects on the stability of adenine-uracil base pairing in chloroform solution by using proton nuclear magnetic resonance methods, where acetamide and butyric acid were used as a model of residues of glutamine and glutamic acid, respectively, and were added to an adenine-uracil equimolar mixture. The stability of base pairing was affected significantly when the model compounds approached the adenine-uracil base pairs; that is, the Hoogsteen type was destroyed, while the Watson-Crick type was formed more favorably.

Acetamides↗
PubMed1987

Association of polyene antibiotics with sterols.

Molecular interaction between amphotericin B and sterols in non-aqueous solutions was examined quantitatively by spectroscopic methods in order to support the view point that selectivity of amphotericin B is more pronounced in the presence of ergosterol than of cholesterol. The most likely association complexes between ergosterol and amphotericin B are 4:1, 6:1 stoichiometric complex when the concentrations of amphotericin B are 3.93 x 10(-4) M, 1.94 x 10(-4) M respectively. The presence of 3 beta-OH group is necessary but not enough for the association with amphotericin B. It appears that the extent of spectral change of amphotericin B induced by complexing sterol is greater for ergosterol than cholesterol.

Amphotericin B↗
PubMed1987

Development of immunoassay methods by use of liposomes.

In order to develop liposomes for use in an immunoassay system, the preparation of immune liposomes and their characterization have been investigated. Liposomes have potential use in extremely sensitive analytical immunoassays, in addition to serving as an attractive drug delivery system. This liposome immunoassay system is based on membrane immunochemistry and an enzymatic reaction. An intense yellow color, easily detectable with the naked eye, was produced quite rapidly by the lysis of bovine serum albumin (BSA)-labeled, alkaline phosphatase-entrapped liposomes in the presence of anti-BSA rabbit serum and active complement under alkaline conditions. Sensitive detection is possible because of the antigen-antibody complex reaction, which leads to liposome lysis and an enzymatic reaction. The liposome immunoassay method offers a rapid, simple, and sensitive testing procedure which can quantitatively and qualitatively determine the presence or absence of antigenic materials and antibodies.

Amines↗
PubMed1985

Effects of purified ginseng saponins on multilamellar liposomes.

To elucidate the mode of interaction between purified ginseng saponins and liposomes, the effects of ginseng saponins at concentrations below and above their critical micelle concentration on the osmotic behavior of liposomes were observed. Liposomes composed of egg phosphatidylcholine (PC), phosphatidic acid (PA) and/or cholesterol (Ch) behave as an ideal osmometer and this activity was described by the linear relationship between (1/A450)3/2 and Cin/Cout. Total saponin prepared from the lateral roots of ginseng cultivated in Korea interacted with multilamellar liposomes and prevented them from behaving as an ideal osmometer. 20-S-Protopanaxadiol saponin showed similar activity but 20-s-protopanaxatriol saponin had weak activity. Ginsenoside Rb1 whose genin is 20-S-protopanaxadiol, disturbed osmotic behavior of Ch-free liposomes but not Ch-containing liposomes as monomers and lyzed both liposomes as micelles. Rg1 whose genin is 20-S-protopanaxatriol, showed no activity on liposomes with or without Ch. It can be suggested that ginseng saponins may interact with and destroy liposomal membranes and that structure of sugar moiety is an important factor to their activities. Ch is not a target in this interaction but suppresses the activity of ginseng saponins.

Brassica↗
PubMed1984

Interaction of sea cucumber saponins with multilamellar liposomes.

The effect of three sea cucumber saponins, echinoside A, bivittoside D and holothurin A, on multilamellar liposomes was investigated. An ideal osmotic behavior of liposomes was described as a linear relationship between the reciprocal 3/2 s power of absorbance at 450 nm and the osmotic gradient across the membrane. Sea cucumber saponins at concentrations below critical micelle concentration (CMC) disturbed this linear relationship in liposomes composed of egg phosphatidylcholine, phosphatidic acid and cholesterol. Cholesterol-free liposomes were not susceptible to these saponins. Results of optical measurements were consistent with those of transmission electron microscopy, which showed saponin-induced changes in liposomal structure. The lytic activity of sea cucumber saponins on liposomes depended on their chemical structure. These results suggest that sea cucumber saponins as monomers can interact with liposomes and that cholesterol serve as a principal binding site for the sea cucumber saponins.

Animals↗
PubMed1983

Molecular interaction between riboflavin and salicylic acid derivatives in nonpolar solvents.

The interaction of riboflavin-2',3',4',5'-tetrabutyrate (I) with salicylic acid (II), aspirin (acetylsalicylic acid, III), and salicylamide (IV) has been spectroscopically investigated to determine the binding mechanism. NMR and absorption spectra were measured in nonpolar solvents. The association constant K of the formation of complex was calculated from the absorption spectra. Compounds I and II form a 1:1 cyclic hydrogen-bonded dimer through the N-3 proton and the C-2 carbonyl oxygen of the isoalloxazine ring, and the carboxylic hydroxyl proton and carbonyl oxygen of II. Compounds I and III form a 1:1 cyclic hydrogen-bonded dimer by the same mode. Compound IV forms a 1:1 cyclic hydrogen-bonded dimer with I through the N-3 proton and the C-2 carbonyl oxygen of the isoalloxazine ring, and the amino proton and the carbonyl oxygen of IV. Salicylates produce marked changes in the absorption spectra of I. These spectral changes are attributed to the formation of the hydrogen-bonded dimer. It appeared that the strongest complex was formed with salicylic acid, a weaker one with aspirin, and an even weaker one with salicylamide.

Chemical Phenomena↗
PubMed1982

Interaction between flavins and alcohols.

The effect of alcohols on the spectral properties of riboflavin derivatives in non-polar solvent was studied by various spectroscopic methods in order to support the view point that alcohol may directly interact with the isoalloxazine moiety of FAD and enhance the catalytic activity of D-amino acid oxidase (DAAO). The most likely association complex between alcohol and riboflavin is 1 : 1 stoichiometric complex through the 3-N imino and the 2-C carbonyl groups of the isoalloxazine ring and the hydroxyl group of alcohols. It appears that methanol has a larger association constant than any other alcohols, and the association constant decreases with the increase in carbon number and with the steric requirement of the alkyl group of alcohols.

Alcohols↗