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Biomedical subjects

K Kakehi

Publications and source records attributed to K Kakehi.

At least 73 records · Page 4Linked to original sources
PubMed1987

Separation of carbohydrates and lectins on carbohydrate-immobilized resins.

A few carbohydrate-immobilized resins were prepared by coupling glycamines of mono- and disaccharides to an epoxy-activated methacrylate base, and the elution profiles of various carbohydrates and lectins from columns packed with the resultant resins were compared. The introduction of glucamine, maltamine or lactamine to the methacrylate base had little effect on the separation of stereoisomers of aldoses, though it enabled group separation of pentoses as well as 6-deoxyhexoses from hexoses. On the other hand, the maltamine-immobilized resin showed strong specific affinity for concanavalin A, as well as lentil and pea lectins. The lactamine-immobilized resin was specific to ricinus agglutinin, peanut agglutinin and soy bean agglutinin. These carbohydrate-immobilized resins were also useful for the isolation of a lectin-like substance from rat liver.

Animals↗
PubMed1987

Fluorometric determination of sialic acids using malononitrile in weakly alkaline media and its application to postcolumn labeling in high-performance liquid chromatography.

A sensitive method for determination of sialic acids by monitoring the fluorescence produced with malononitrile in borate buffer has been established. Measurement of the fluorescence intensity of the reaction mixture at 430 nm with irradiation at 360 nm allowed determination of 3-60 nmol of sialic acids with high reproducibility. A few amino sugars and deoxy sugars, as well as catecholamines reacted with this reagent; however other carbohydrates, amino acids, amines, aldehydes, and carboxylic acids including alpha-keto acids, etc., showed little reactivity. This method was successfully applied to postcolumn fluorescence labeling of sialic acids in high-performance liquid chromatography.

Animals↗
PubMed1987

Catecholamine levels in the brain of SART (repeated cold)-stressed rats.

1 The catecholamine levels in the brains of SART (specific alternation of rhythm in temperature)-stressed (repeated cold-stressed) rats with vagotonic-type dysautonomia, were examined by high performance liquid chromatography with electrochemical detection techniques. 2 The cerebral cortex, hypothalamus and hippocampus of the SART-stressed rats had increased levels of noradrenaline. All brain areas examined showed increased levels of dopamine. 3 These increased catecholamine levels were still maintained by day 10 of SART stress. 4 Among brain areas examined, the hypothalamus showed most rapid change. 5 Cold-stressed rats showed increased noradrenaline levels only in the basal ganglia and dopamine levels in the hippocampus. 6 Rats suffering from restraint and water immersion stress showed decreased noradrenaline levels and increased dopamine levels. 7 These results suggest that SART-stressed animals are in a disease state differing from that of other so-called stressed animals, and changes in the hypothalamus give rise to the various symptoms in SART-stressed animals.

Animals↗
PubMed1986

Profiling of carbohydrates, glycoproteins and glycolipids.

Current chromatographic methods for the analysis of a variety of carbohydrate materials in body fluids and tissues have been reviewed, from the viewpoints of clean-up of samples, separation modes, methods for detection and quantification, and degree of convenience. This review also contains several tables, listing names of samples, methods of analysis, analytical conditions, and normal as well as pathological levels reported, from representative publications.

Animals↗
PubMed1986

The instrument accuracy limit for objectively measuring the loudness rating of telephone systems.

This paper investigates a sensitivity measurement method for carbon transmitters and a calculation method for the loudness rating of a telephone system. The sensitivity varies depending on the artificial voice used for the measurement and the conditioning procedures. The most preferable methods for obtaining values which coincide with those in the subjective loudness rating test are discussed. With respect to the loudness calculation method, the algorithm, parameter values, ear leakage loss, and voice spectrum are discussed. As a result of these investigations, the deviation between the objective and subjective rating is found to be 0.7 dB for the various types of handset telephones when the measurement conditions are optimized. This deviation is considered to be the limit of measurement accuracy. The performance of currently developed objective measurement instruments is close to this limit. Considering the fluctuations accompanying repetitive subjective measurements, the objective rating corresponds satisfactorily with the subjective rating.

Humans↗
PubMed1985

Functional and morphometric study of the liver in motor neuron disease.

In routine liver function tests, 23 of 44 patients with motor neuron disease (MND) had abnormal findings, and there was disturbance of unconjugated bilirubin metabolism in 10 of the 33 patients tested. Liver-biopsy specimens from 10 MND patients were compared by electron microscopic examination with specimens from age-matched controls who had chronic persistent hepatitis. The MND patients had a higher incidence of intramitochondrial inclusions, less abundant mitochondria in a given area of cytoplasm and enlarged mitochondria. Electron-probe X-ray microanalysis of hepatocytic lysosomes found copper in 8 of 13 MND patients, but not in the controls. These findings suggest that the pathogenetic processes in MND may involve not only motor neurons but also hepatic cells.

Adult↗
PubMed1983

Automated analysis of hexosamines by high-performance liquid chromatography with photometric and fluorimetric postcolumn labeling using 2-cyanoacetamide.

Glucosamine and galactosamine were well separated in ca. 60 min on a Hitachi 2617 column (polystyrene sulfonate type, 4 mm X 25 cm) with a borate buffer (pH 7.5) containing sodium chloride. The hexosamines in the eluate were monitored fluorimetrically and photometrically at 331 (excitation)/383 (emission) and 276 nm, respectively, by postcolumn labeling with 2-cyanoacetamide. This simple method allowed the simultaneous, automated determination of 10-500 nmol of glucosamine and galactosamine with high reproducibility. This method was applied successfully to the analysis of hexosamines in some glycoconjugates.

Adult↗
PubMed1983

Automated analysis of uronic acids by high-performance liquid chromatography with photometric and fluorimetric postcolumn labelling using 2-cyanoacetamide.

A convenient method for the rapid and sensitive automated analysis of uronic acids, based on high-performance anion-exchange chromatography on a Hitachi 2633 column and photometric as well as fluorimetric postcolumn labeling with 2-cyanoacetamide, has been developed. This method allows the simultaneous determination of 1-1000 nmol of D-mannuronic and D-galacturonic acids and 5-1000 nmol of L-iduronic and D-glucuronic acids in approx 70 min with high precision by photometric monitoring. In fluorimetric monitoring the linearity range was 1-1000 nmol for all these uronic acids, but reproducibility was rather low at the lowest limit of linearity. Application of this method to the analysis of component uronic acids in some polyuronides has suggested the inadequacy of generally accepted conditions for hydrolysis.

Animals↗
PubMed1983

Postcolumn derivatization of catecholamines with 2-cyanoacetamide for fluorimetric monitoring in high-performance liquid chromatography.

Catecholamines in the eluates of high-performance liquid chromatography were reacted with 2-cyanoacetamide in borate buffer in flow analysis mode, and the intensity of fluorescence developed was recorded. Under the optimum conditions (column: Hitachi 3011 C, 25 cm X 2.6 mm I.D., 45 degrees C; eluent: 0.05 M KH2PO4 containing 0.05% H3PO4, 0.60 ml/min; reagent solution: a mixture of 1% 2-cyanoacetamide, 0.50 ml/min, and a 0.60 M H3BO3--KOH buffer, 1.0 ml/min; size of reaction coil: 5 m X 0.5 mm I.D.; reaction temperature: 100 degrees C; wavelengths for detection: 383 nm for excitation and 486 nm for emission), this method allowed simultaneous determination of 5-500 pmol catecholamines with high reproducibility. The lower limits of detection (signal-to-noise ratio = 2) for epinephrine, norepinephrine and dopamine were 0.28, 0.11 and 0.098 pmol, respectively. Some applications of the analysis of urinary and serum catecholamines are also presented.

Catecholamines↗
PubMed1983

Automated analysis of alditols by anion-exchange chromatography with photometric and fluorimetric postcolumn derivatization.

Eight alditols were separated in ca. 80 min as their borate complexes by stepwise elution with three borate buffers on a column packed with Hitachi 2633 resin. The alditols in the eluate were derivatized automatically to colored, fluorescent products by applying sequential reactions of periodate oxidation and Hantzsch condensation, and the products were detected either photometrically or fluorimetrically. This automated method allowed simultaneous determination of 20-500 and 20-200 nmol amounts of alditols by photometric and fluorimetric monitorings, respectively. The lower limits of detection were ca. 2 and 0.5 nmol, respectively. The interference by aldoses was slight. Aldoses may be also determined as alditols by direct injection of aqueous solutions to which excess amounts of sodium borohydride have been added. This method was applied with success to urinary alditol assay and to molecular weight determination by end group analysis.

Adult↗
PubMed1983

Analysis of sialic acids by gas chromatography of the mannosamine derivatives released by the action of N-acetylneuraminate lyase.

A convenient method for the analysis of sialic acids is proposed, which is based on their dissociation into pyruvate and N-acylmannosamines by the action of N-acetylneuraminate lyase, followed by gas-chromatographic analysis of the latter products as trimethylsilylated diethyl dithioacetals. Conjugated sialic acids should be freed with neuraminidase before being subjected to the action of the lyase, but these sequential enzymic reactions may be performed in one pot. N-Acetyl-, N-glycolyl- and N,O-diacetylneuraminic acids gave the corresponding mannosamines, and the dithioacetal derivatives of these mannosamines were well separated on a column of silicone OV-1. Quantitation of this enzymic and gas chromatographic method indicated that the error and coefficient of variation for free N-acetylneuraminic acid were 1.1% and 2.5%, respectively, for ten determinations at the 100 nmol level. The values for conjugated N-acetylneuraminic acid in N-acetylneuraminlactose were 2.9% and 5.9%, respectively. This method was applied to the analysis of sialic acids in some biological samples, and the results were compared with those obtained by the conventional colorimetric method. Preliminary data on urinary sialic acids indicated that cancerous patients gave significantly higher levels of urinary N-acetylneuraminic acid than normal subjects.

Adult↗