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K Kakehi

Publications and source records attributed to K Kakehi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Capillary electrophoresis of N-acetylneuraminic acid polymers and hyaluronic acid: correlation between migration order reversal and biological functions.

High-resolution analysis of polymers of N-acetylneuraminic acid and hyaluronic acid was performed by capillary electrophoresis in a buffer containing a neutral polymer. Both polysaccharides having more than 100 monosaccharide residues were well separated into their molecular species by capillary electrophoresis using a combination of a chemically modified capillary and a buffer containing poly(ethylene glycol) as an additive. During optimization of the separation conditions, small oligomers of both polysaccharides were observed to migrate in the reverse order of their molecular masses on the electropherograms. However, oligomers larger than pentamer and decamer for N-acetylneuraminic acid polymers and hyaluronic acid, respectively, migrated in the order of their molecular masses. We propose that these unusual migration patterns are closely related to the stereochemical structures and the oligomer migrating the fastest is the minimum unit that forms the regular three-dimensional structure required for the biological function.

Carbohydrate Sequence↗
PubMed1999

In vitro regioselective stability of beta-1-O- and 2-O-acyl glucuronides of naproxen and their covalent binding to human serum albumin.

beta-1-O- (NAG) and 2-O-glucuronides (2-isomer) of (S)-naproxen (NA) were prepared to determine which positional isomer(s) of the acyl glucuronide of NA is responsible for forming covalent adducts with human serum albumin (HSA). Their comparative stability and covalent binding adduct formation with HSA were investigated at pH 7.4 and at 37 degreesC. NA and its acyl glucuronides were simultaneously determined by HPLC. Three positional isomers were formed successively after incubation of NAG in the buffer only. However, when NAG was incubated with HSA (30 mg/mL), isomers other than the 2-isomer were formed in little or negligible quantities. In HSA solution, NAG (kd = 2.08 +/- 0.08 h-1) was four times less stable than 2-isomer (kd = 0.51 +/- 0.02 h-1). NAG was degraded by hydrolysis (khyd = 1.01 +/- 0.10 h-1) and isomerization (kiso = 1.07 +/- 0.07 h-1) to the same extent; however, hydrolysis was predominant for the 2-isomer (kd = 0.51 +/- 0.02 h-1). The incubation of both NAG and 2-isomer with HSA led to the formation of a covalent adduct; however, the adduct formation from the 2-isomer proceeded more slowly than that from NAG. The present results suggest that the covalent binding of NA to HSA via its acyl glucuronides proceeds through both transacylation (direct nucleophilic displacement) and glycation mechanisms; NAG rapidly forms an adduct that may be unstable, and the protein adduct from the 2-O-acyl glucuronide is as important for the covalent binding as those from the 1-O-acyl glucuronides.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Sulfated sialic acid-polymers inhibit the cytotoxic action of bee and snake venom.

Colominic acid is an alpha2,8-linked sialic acid polymer produced by Escherichia coli. We found that synthetic sulfated-colominic acids (SC) remarkably inhibited the cytotoxicity of bee and snake venom toward mouse fibroblast cells, but colominic acids showed no inhibition themselves, indicating the important role of sulfate groups in the inhibitory activity of SC. Other sulfated carbohydrates such as chondroitin sulfates, heparin and heparan sulfate showed no inhibition. SC also exhibited potent inhibition of melittin, a highly basic peptide, which is a major cytotoxic component of bee venom. SC did not inhibit phospholipase A2 activity in bee venom. This suggests that the inhibition of bee and snake venom by SC is due to inhibition of melittin and cardiotoxin, which is a cytolytic peptide in snake venom, respectively. SC with a higher sulfur content and a larger molecular mass showed more potent activity. The interaction between SC and melittin basically seems an ionic one, however, the conformation of SC is also likely important. For the binding of SC to melittin leading loss of its cytotoxic activity, the sulfate groups of SC must be properly arranged to interact with lysine and arginine residues of melittin molecules, which play an important role in the cytolytic activity. A higher molecular mass of SC substituted with more sulfate groups is required for more obvious inhibition of the cytotoxic activity.

Animals↗
PubMed1999

Release characteristics of endogenous constituents by exposure of small intestine to modified beta-cyclodextrins.

The aim of the present research is to characterize the leakage of intestinal constituents induced by beta-cyclodextrin (beta-CyD) derivatives using an in situ perfusion and an in vitro everted sac. The efficacy of 6-O-alpha-D-glucosyl (G1)- and 6-O-alpha-D-maltosyl (G2)-beta-CyDs as oral carriers was also compared with that of 2-hydroxypropyl-(HP1; average molar degree of substitution, 0.9) and 2,6-di-O-methyl (DM)-beta-CyDs. In the in situ studies, phenol red (PR) penetration and the release profiles of intestinal constituents for G2-beta-CyD were fairly close to those for HP1-beta-CyD. However, the ability of G2-beta-CyD to include cholesterol was greater than that of HP1-beta-CyD. To characterize the release of intestinal constituents induced by modified beta-CyDs, the capability of including cholesterol was held constant between DM- and branched beta-CyDs. The everted sac study showed that the amount of DM-beta-CyD transferred to the serosal side was not significantly different from the branched beta-CyDs. On the serosal side, the amount of cholesterols released was approximately 3 times higher for DM-beta-CyD than for the branched beta-CyDs at 60 min. The cumulative amounts of cholesterols for DM-beta-CyD increased approximately 6 times at 60 min compared with at 30 min, predominating over the leakage (average 2.6-fold) on the mucosal side. In contrast, the exposure of the branched beta-CyDs resulted in an insignificant increase over the period of this experiment. The present study suggests that permeable beta-CyD derivatives play an important role in the leakage of intestinal components. G2-beta-CyD is preferably recommended as a drug solubilizer in oral formulations as well as HP1-beta-CyD, based on the lower release of intestinal constituents.

Administration, Oral↗
PubMed1999

[Examination of the stability of chloral hydrate and its preparation by capillary electrophoresis].

Stabilities of chloral hydrate in an aqueous solution and its medicated syrup were examined by high performance capillary electrophoresis. Analysis of the concentration of chloral hydrate indicated that there was no obvious change in the concentration of chloral hydrate both in the aqueous solution and in the syrup preparation after keeping them for 3 months at room temperature or at 60 degrees C. The lowering of pH was more obvious in the syrup solution than in the aqueous solution, and this tendency was estimated to be due to the formation of hydrochloric acid. We propose that the stabilities of the preparation of chloral hydrate should be monitored by observing pH changes.

Chloral Hydrate↗
PubMed1998

Simultaneous determination of nicotinic acid and its metabolites in rat urine by micellar electrokinetic chromatography with photodiode array detection.

Nicotinic acid, nicotinamide and their possible metabolites were successfully separated within 17 min by micellar electrokinetic chromatography using 50 mM borate buffer (pH 9.0) containing 150 mM sodium dodecyl sulfate as the running buffer. Calibration curves for all compounds showed good linearity in a range of 5 microg/ml and 250 microg/ml with good correlation. The present method did not require any clean-up procedures and made it possible to determine all metabolites without interference on a photodiode array detector. Urine samples collected from Wistar male rats were analyzed after high-dose oral or intravenous administration of nicotinic acid or nicotinamide. Metabolic pathways of nicotinic acid in male Wistar rats are also discussed.

Animals↗
PubMed1998

Analysis of glucuronolactone and glucuronic acid in drug formulations by high-performance liquid chromatography.

Glucuronolactone and glucuronic acid in drug formulations and beverages are determined as 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatives using high-performance liquid chromatography. Intra-ester linkage (i.e., the lactone of glucuronolactone) is spontaneously hydrolyzed to free-acid form and is analyzed as the PMP derivative of glucuronic acid. By omitting three evaporation steps in the original derivatization procedure, the total analysis time is shortened to approximately 40 min. Reproducibility of determination is within 4.0% for all drug formulations. The present method satisfies the requirements for routine analysis in the quality control of drug formulations containing glucuronolactone or glucuronic acid.

Antipyrine↗
PubMed1998

Evaluation of fluorescence polarization method for binding study in carbohydrate-lectin interaction.

The fluorescence polarization (FP) technique was evaluated to determine molecular interaction between plant lectins and polysaccharides, yeast cells and glycopeptide after labeling the lectins with fluorescein isothiocyanate. Use of Lycoris radiata agglutinin allowed determination of the molecular interactions with large biomolecules containing mannose oligomers and polymers. Another example using a fluorescein-labeled glycopeptide also indicated that use of the FP method would allow easy observation of the molecular interactions on the quantitative base. The present technique is highly sensitive and facile because it does not require any washing procedures before measurement.

Binding Sites↗
PubMed1997

Fluorometric assay of binding specificity of plant lectins to yeast cells by biotin-avidin system and its application to the classification of yeast cells.

A fluorometric assay of lectin binding to yeast cells is reported. The relative amount of biotinylated lectins bound to the yeast cells was estimated by enzyme activity using 4-methylumbelliferyl-beta-D-galactoside as a substrate for the lectin-bound beta-galactosidase through biotin-avidin interaction. Binding properties of 4 mannose-specific and 3 glucose/mannose-specific lectins to 22 different species of yeast cells were studied. The binding reaction of biotinylated lectins to the yeast cells was rapid and became constant within 10 min. Each lectin showed its characteristic binding specificity to each yeast species. The relative fluorescent intensities observed for 4-methylumbelliferone released by the action of bound beta-galactosidase were good indicators for the classification of yeast cells in quantitative base. We found that the yeast cells of the Saccharomyces genus can be classified into three groups, and those of Pichia were grouped into two groups. The present method can examine many samples simultaneously and be completed within 3 h.

Agglutination↗
PubMed1997

Use of a binary mixture of quaternary ammonium salts in fluorometric determination of glycosaminoglycans.

The concentration of glycosaminoglycans, in an aqueous solution was determined by observing the fluorescent intensity of the ion of 2-hexadecyl-9H-pyrido[4,3b]indole at 450 nm by irradiating 253-nm light after dissolution of the insoluble salt in ethanol, which was formed by the reaction between a solution of a sample of glycosaminoglycan and an aqueous solution of the binary mixture of fluorescent 2-hexadecyl-9H-pyrido[4,3b]indolium bromide and hexadecyl pyridinium chloride. The fluorescent quaternary ammonium salt, which was slightly soluble in water, was solubilized in water by forming mixed micelles with a nonfluorescent soluble quaternary ammonium salt. The present method showed good linearity for the calibration curves between 5 and 1000 micrograms/ml in all samples of glycosaminoglycan except keratan sulfate. The relative standard deviation in determination was less than 3% for the whole calibration range.

Chondroitin Sulfates↗
PubMed1997

High-performance capillary electrophoresis of hyaluronic acid: determination of its amount and molecular mass.

The amount and the molecular mass of hyaluronic acid (HA) were determined by high-performance capillary electrophoresis. HA was observed at around 15 min by using an untreated fused-silica capillary (75 microns I.D.) of 58 cm length (effective length, 50 cm) at 20 kV in 50 mM phosphate buffer (pH 4.0). Calibration curves showed good linearity from 0.01 mg/ml to 3.3 mg/ml for all HA samples examined. The lower limit of detection by monitoring the absorbance at 185 nm was 1.0 microgram/ml at the signal-to-noise ratio of 5. HA samples were examined in a buffer containing pullulan (PU) as an additive for the matrix formation material. The HA samples showed marked peak-broadening when analyzed in the buffer solution containing PU with a specified molecular mass. The peak broadening was based on the dispersion of the molecular mass of the HA sample analyzed.

Buffers↗
PubMed1997

Telescience for the reduced gravity flight experiments.

To improve the efficiency of the preliminary experiments for the JEM, the telescience capabilities have been implemented into the parabolic flight experiments on the small jet plane. In this paper, we will describe the results of the 1st telescience support experiments using the two commercial airline telephone system. In the experiments, these lines have been used not only for the voice communication, but also for the data transfer, such as FAX, still TV image transmission, and data transfer. Utilizing these capability, human physiological experiment was tested as the sample experiment. The parabolic flights were done in the two major training/testing area, that are C & K area.

Aerospace Medicine↗
PubMed1996

Comparison of the sensitivities of various derivatives of oligosaccharides in LC/MS with fast atom bombardment and electrospray ionization interfaces.

Sensitivities of the following derivatives of oligosaccharides in MS and LC/MS with frit FAB and ESI interfaces were compared under the conditions where samples were supplied to the probes in solutions at constant rates: 2-aminopyridine, 4-aminobenzoic acid ethyl ester (ABEE), 1-phenyl-3-methyl-5-pyrazolone (PMP) as well as 4-methoxyphenyl analogue, 2-aminoethanethiol, and 2-aminobenzenethiol. In FAB-MS, maltopentaose labeled with ABEE gave the most abundant [M + H]+ ions in positive ion mode when ionized in thioglycerol or glycerol matrix supplied in 50% (v/v) aqueous methanol. The lowest limit of detection was obtained for this compound in these matrices in water. The [M - H]- ion in negative ion mode was also abundant in all matrices examined in both 50% (v/v) aqueous methanol and water. On the other hand PMP derivatives gave the highest sensitivities in ESI-MS under the optimized conditions. On the basis of these findings, authentic oligosaccharides and oligosaccharides derived from a few glycoprotein samples were analyzed by LC/MS with frit FAB and ESI interfaces. The results indicated the usefulness of these derivatives for simultaneous microanalysis of oligosaccharides.

Carbohydrate Sequence↗
PubMed1996

Analysis of glycoproteins, glycopeptides and glycoprotein-derived oligosaccharides by high-performance capillary electrophoresis.

Recent developments in the analysis of glycoproteins by high-performance capillary electrophoresis are reviewed, with emphasis on their carbohydrate chains. Glycoforms of glycoproteins were directly separated from each other by careful optimization of the analytical conditions. Glycopeptides in tyrptic digests were separated and the peptides carrying glycosylation sites were differentiated from others. Released oligosaccharide chains were separated from each other by direct or modified zone electrophoresis and directly detected by measuring the UV absorption at a low wavelength. Precolumn derivatization by various methods extended the utility of both the separation mode and detection technique. Dual mode analysis after derivatization permitted reliable identification and quantification without references.

Carbohydrate Sequence↗
PubMed1995

Modality dependency of familiarity ratings of Japanese words.

Familiarity ratings for a large number of aurally and visually presented Japanese words wer measured for 11 subjects, in order to investigate the modality dependency of familiarity. The correlation coefficient between auditory and visual ratings was .808, which is lower than that observed for English words, suggesting that a substantial portion of the mental lexicon is modality dependent. It was shown that the modality dependency is greater for low-familiarity words than it is for medium- or high-familiarity words. This difference between the low- and the medium- or high-familiarity words has a relationship to orthography. That is, the dependency is larger in words consisting only of kanji, which may have multiple pronunciations and usually represent meaning, than it is in words consisting only of hiragana or katakana, which have a single pronunciation and usually do not represent meaning. These results indicate that the idiosyncratic characteristics of Japanese orthography contribute to the modality dependency.

Adolescent↗
PubMed1994

High-performance capillary electrophoresis of O-glycosidically linked sialic acid-containing oligosaccharides in glycoproteins as their alditol derivatives with low-wavelength UV monitoring.

Several O-glycosidically linked monosialooligosaccharides from glycoproteins were separated as their alditol derivatives in ca. 10 min in borate buffer (pH 9.6) containing sodium dodecyl sulfate (SDS), and sensitively detected at the 10(-4) M level by measuring absorption at 185 nm. Oligosaccharides having higher degree of polymerizations migrated faster, and N-acetyl- and N-glycolylneuraminic acid-containing oligosaccharide analogues could be resolved from each other under the conditions employed. Good linearity was demonstrated between 0.9 and 20 mM concentrations for relative response of N-acetylneuraminyllactose as a model compound to lactobionic acid as an internal standard. The detection limit was 0.2 mM, which corresponded to 0.80 pmol as the injected amount. The relative standard deviation of relative response at 9 mM was 1.97% (n = 7). The established system was successfully applied to microanalysis of sialooligosaccharides in bovine submaxillary mucin and swallow nest material.

Animals↗