Biomedical subjects

D Ishii

Publications and source records attributed to D Ishii.

31 records · Page 2Linked to original sources

PubMed1983

Determination of catecholamines in human serum by micro high-performance liquid chromatography with micro precolumn and dual electrochemical detection.

A dual electrochemical detector having two working electrodes (anode and cathode) in parallel--opposed configuration suitable for micro high-performance liquid chromatography was developed for the selective and sensitive detection of catecholamines on the basis of their electrochemical reversibility and catalytic amplification by recycling oxidation and re-reduction. The micro high-performance liquid chromatographic system with a micro alumina precolumn for enriching catecholamines and the dual electrochemical detector in parallel--opposed configuration was successfully utilized for the determination of catecholamines in healthy human serum injected directly after ultrafiltration.

Catecholamines↗

PubMed1983

Micro high-performance liquid chromatographic separations of bile acids.

Separations of bile acids by micro high-performance liquid chromatography (micro-HPLC) using an immobilized 3 alpha-hydroxysteroid dehydrogenase post-column and a spectrofluorimeter are described. The sensitivity of detection is greatly increased by pre-mixing beta-nicotinamide adenine dinucleotide with the mobile phase, using a single pump. The detection limit is 0.04-0.7 ng, depending on the solute. Instruments suitable for the analysis of bile acids in micro-HPLC are discussed.

Bile Acids and Salts↗

PubMed1982

Dual electrochemical detector for micro high-performance liquid chromatography and its application to the selective detection of catecholamines.

A dual electrochemical detector having two working electrodes (anode and cathode) suitable for micro high-performance liquid chromatography has been characterized for the selective detection of catecholamines on the basis of their electrochemical reversibility. The rapid determination of applied potentials for such electrochemical detectors in liquid chromatography by means of cyclic semi-differential voltammetry is described. The dual electrochemical detector has been successfully utilized for the selective determination of catecholamines in human urine injected directly into a micro high-performance liquid chromatograph with an alumina preconcentration micro-column.

Catecholamines↗

PubMed1981

Micro high-performance liquid chromatographic system with micro precolumn and dual electrochemical detector for direct injection analysis of catecholamines in body fluids.

A new micro high-performance liquid chromatographic system has been developed, which determines catecholamines from directly injected human urine without any sample pretreatment. The system consists of a mixing junction for adjusting the sample to pH 8.5, a micro alumina precolumn for enriching catecholamines in the sample, and a dual electrochemical detector for selectively detecting catecholamines based on their electrochemical reversibility. The system is able to operate with directly injected body fluids and to determine simultaneously all of the four catecholamines with high precision.

Catecholamines↗

PubMed1980

Analgesic and other pharmacological activities of a new narcotic antagonist analgesic (-)-1-(3-methyl-2-butenyl)-4-[2-(3-hydroxyphenyl)-1-phenylethyl]-piperazine and its enantiomorph in experimental animals.

Of 1-chclohexyl-4-[2-(3-hydroxyphenyl)-1-phenylethyl]piperazine (I) and its 1-(3-methyl-2-butenyl) derivative (II), the S(+)-isomers were analgesically more active than either their +(-)-isomers or their racemates, having 15 to 44 times the potency of morphine in mice and rats. R(-)-I had comparable analgesic activity to morphine R(-)-II to pentazocine in mice, rats and dogs and they were nearly equipotent with pentazocine in reversing some actions of morphine. The S(+)-isomers and racemates lacked this action. R(-)-II required about 10 times more naloxone to reverse its analgesic activity than was needed to antagonise the S(+)-isomers, morphine and pentazocine. The S(+)-isomers and racemates produce a typical Straub tail reaction and increased spontaneous locomotor activity in mice, but the R(-)-isomers did not. R(-)-II had no significant physical dependence liability in mice, rats and monkeys. From these results, it is suggested that the compounds show an uncommon steroselectivity in comparison with morphine and its surrogates, and that R(-)-II is worth investigating further as a narcotic antagonist analgesic.

Analgesics↗

PubMed1978

Studies of microhigh-performance liquid chromatography. IV. Application of the micro pre-column method to the analysis of corticosteroids in serum.

The micro pre-column method, which is a useful method for the pre-treatment of samples, was applied to the analysis of corticosteroids in serum. Corticosteroids were concentrated in a micro pre-column packed with porous styrene-divinylbenzene copolymer particles and separated in a micro separation column packed with porous silica particles. Concentrations of corticosterone, cortisone and cortisol in the 20-130 ppb range were determined individually by pre-treatment of only 0.2 ml of serum.

Adrenal Cortex Hormones↗

PubMed1972