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Biomedical subjects

Y Matsuki

Publications and source records attributed to Y Matsuki.

At least 109 records · Page 6Linked to original sources
PubMed1987

Determination of chinoform in biological fluids and nervous tissues of the dog by gas chromatography-mass spectrometry.

A sensitive gas chromatographic-mass spectrometric method for the determination of 5-chloro-7-iodo-8-hydroxyquinoline (chinoform, clioquinol) in biological fluids and nervous tissues is described. Chinoform was converted into the pentafluorobenzyl ether, which was separated on a 10% Dexsil 300GC column and determined by the use of chinoform-d4 as an internal standard. The clean-up of chionoform in plasma and urine was efficiently achieved by extracting with benzene, while the drug in the tissue was pretreated successively by extraction with 12.5% v/v pyridine-benzene, separation on a Clin-Elut cartridge and adsorption on alumina. The quantitation limit of chinoform was 100 pg, and the recovery rates of chinoform added to plasma and tissue were 98% and 92%, respectively. The chinoform levels in biological fluids and tissues in dogs after prolonged administration of the drug at a dose of 400 mg/kg/day were measured by the proposed method. The plasma level and tissue distribution of chinoform are also discussed.

Animals↗
PubMed1986

Examination of Chinese and U.S.S.R. cereals for the Fusarium mycotoxins, nivalenol, deoxynivalenol and zearalenone.

Cereals, foods and feeds sampled in Taiwan, China and the U.S.S.R. were contaminated with nivalenol, deoxynivalenol and zearalenone. The frequencies and levels of contamination are similar to those observed in the cereals of Japan and Korea. This is the first report on the natural occurrence of nivalenol, deoxynivalenol and zearalenone in Chinese and U.S.S.R. cereals, foods and feeds.

China↗
PubMed1985

Rapid and sensitive determination of zearalenone in cereals by high-performance liquid chromatography with fluorescence detection.

Zearalenone, an estrogenic mycotoxin of Fusarium species, in cereals can be extracted with acetonitrile-water (3:1), purified on a Florisil column, resolved by high-performance liquid chromatography (HPLC) with a Nucleosil 50-10 column using 90% water-saturated chloroform-cyclohexane-acetonitrile-ethanol (50:15:2:1) and quantitated by fluorescence measurement. This method is rapid, simple and reproducible, and detects zearalenone in wheat, barley, corn and other cereals with picogram sensitivity. A combination of this HPLC method with a gas-liquid chromatographic method for trichothecenes may be applied to the simultaneous detection of Fusarium mycotoxins (zearalenone, nivalenol and deoxynivalenol) in cereals.

Chromatography, High Pressure Liquid↗
PubMed1985

Separate determination of ethylenediaminetetraacetic acid and its calcium chelate in foods by colorimetry.

A simple colorimetric method is described for the separate determination of ethylenediaminetetra acetic acid (free EDTA) and its calcium chelate (Ca-EDTA) in commercial foods. The underlying principle of the method is that free EDTA is adsorbed by a cation exchange column, but Ca-EDTA is not under weak alkaline conditions. The sample was homogenized with 0,1 n-NaOH and then subjected to equilibrium dialysis against 0,02 n-NaOH at ambient temperature for a definite time (not less than 12 h). An aliquot of the dialysate was measured into a beaker. After the pH of the solution had been adjusted to 8.5 it was applied to a pre-packed cation-exchange column (Amino-form). Free EDTA was adsorbed by this column, whilst Ca-EDTA passed through it without any loss. For assay of Ca-EDTA, the pH of the eluate was adjusted to 2.5, followed by the addition of an excess amount of CuSO4 to convert Ca-EDTA into Cu-EDTA. This solution was then divided into two portions of equal volume. One portion was subjected to the assay of free copper ions, and the other to the assay of total (the sum of free and chelated) copper ions. The difference between the two values is a measure of Ca-EDTA. For the assay of free EDTA, EDTA adsorbed by the column was eluted with 0.5 n-acetate buffer (pH 5.0), followed by the treatment in the same manner as in the case of Ca-EDTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed1985

Colorimetric determination of ethylenediaminetetra-acetic acid in foods.

A simple colorimetric method is described for the determination of ethylenediaminetetra-acetic acid (EDTA) in three kinds of foods. The samples were homogenized with 0.1 N-NaOH, then subjected to equilibrium dialysis against 0.02 N-NaOH. EDTA in the dialyzate was converted into a Cu-EDTA complex by the addition of CuSO4. Afterwards, this solution was subjected to the determination of both free and total (free plus complexed) copper ion. EDTA was calculated from the difference between the absorbances (477 nm) obtained with free and total copper ions. Analyses of mayonnaise, dressings and canned mushroom samples with EDTA added at the 1-mM level showed a recovery of greater than 98%.

Colorimetry↗
PubMed1985

Dynamic stiffness of the isolated guinea-pig gall-bladder during contraction induced by cholecystokinin.

The visco-elastic properties of the isolated guinea-pig gall-bladder were investigated by the dynamic method. The sinusoidal volume changes (up to 0.2 ml) and the resulting sinusoidal pressure changes were displayed on the cathode ray oscilloscope, the volume being on abscissa and the pressure on ordinate. The frequencies of the sinusoidal change in volume were 0.17-0.5 Hz which were 10 times higher than those in Schoetz et al.'s work (Am. J. Physiol. 241: G376-G381, 1981). The dynamic pressure-volume relation of the resting gall-bladder was nearly linear, but showed the elliptical hysteresis loop during CCK- or ACh-induced contractions. If frequencies of the sinusoidal change in volume were increased to 1.7-3.3 Hz, the hysteresis loop for either relaxing or contracting gall-bladder became narrow and guiter-shaped. The dynamic stiffness, the slope of the hysteresis loop or the ratio of the maximum of pressure change to the maximum of volume change, increased in linear proportion to intraluminal pressure rise during contraction. The data could be analysed on the assumption that the visco-elastic property of the gall-bladder was explained by two Voigt models placed in series. The one indicated the property of the smooth muscle tissue, and it had low elastance at the resting state, or middle-grade elastance together with high viscous resistance at the contraction state. Another one had high elastance and low viscous resistance, and it was characterized by collagen fibers involved within the organ.

Acetylcholine↗
PubMed1985

[Spontaneous contractions and the visco-elastic properties of the isolated guinea-pig gall-bladder].

The isolated guinea-pig gall-bladder showed the spontaneous changes in luminal pressure at the rate of 7-12/min at 38 degrees C. These spontaneous contractions were increased in rates as the increase in luminal volume. On the other hand, they were reduced in rates and in amplitudes by lowering the temperatures. Decrease in [Ca2+]o from 2.4 mM to 0.8 mM depressed or even abolished the spontaneous contractions, whereas increase in [Ca2+]o from 2.4 mM to 7.2 mM produced slow pressure rise accompanied with small pressure fluctuations, suggesting that [Ca2+]i was increased as the results of facilitation of Na-Ca exchange mechanism. The pressure-volume relation measured during the first inflation was steeper than that during the following deflation; namely, the gall-bladder showed plasticity. The visco-elastic property was investigated by recording the time course of the pressure change, stress relaxation, following the sudden increase in volume. Thus, the tissue visco-elasticity was divided into three components; the instantaneous elastic component and two viscoelastic components that had the time constants of 4-12 sec and of 5-10 min.

Animals↗
PubMed1982

Determination of captopril and its disulphide in biological fluids.

A gas chromatographic-mass spectrometric method for the simultaneous determination of captopril (SQ 14,255) and its disulphide (SQ 14,551) in biological fluids by means of selected ion monitoring is described. In order to prevent oxidative degradation, captopril was treated with N-ethylmaleimide (NEM). The captopril-NEM adduct and the disulphide were converted into the hexafluoroisopropyl esters, which were separated on a 10% Dexsil 300 GC column and determined by employing the captopril-N-butylmaleimide adducts as an internal standard. The blood and urine levels of captopril and its disulphide in dogs to which captopril had been administered orally were measured by the proposed method. The urinary excretion of these two substances in rats was also determined in a similar manner.

Animals↗
PubMed1981

Characterization of aminoindamines and aminoindoanilines formed by oxidative hair dyeing and their mutagenicity.

2-Amino-5-methoxy-2'(or 3')-methylindamine and 2-amino-5-methoxy-2'(or 3')-methylindoaniline were isolated from a coloring matter formed by oxidative condensation of 2,5-diaminotoluene with 2,4-diaminoanisole, and their structures were elucidated on the basis of nuclear magnetic resonance and mass spectral data. These two main components of the oxidation product formed at the early stage exhibited a positive result in the mutagenicity test on the thin-layer chromatography plate. The mutagenic activities of purified aminoindamines and aminoindoanilines against Salmonella typhimurium TA 98 were as strong as that of 2-acetamidofluorene. It was also demonstrated that 5-methoxy-2'(or 3')-methylindamine was formed in 10% yield under the conditions used for hair dyeing and the yield was dependent upon the molar ratio of 2,5-diaminotoluene to 2,4-diaminoanisole.

Aniline Compounds↗