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K Tsujii

Publications and source records attributed to K Tsujii.

At least 19 recordsLinked to original sources
PubMed2006

Menger sponge-like fractal body created by a novel template method.

We have established experimental strategies on how to create a Menger sponge-like fractal body and how to control its fractal dimension. The essence was to utilize alkylketene dimer (AKD), which spontaneously forms super-water-repellent fractal surface. We prepared "fractal AKD particles" with fractal surface structure as templates of pores in fractal body. The fractal body was synthesized by filling the remained space between the packed template particles with a tetramethyl orthosilicate solution, solidifying it by the sol-gel process, and removing the template by calcinations. We have succeeded in systematically creating fractal bodies of silica with different cross-sectional fractal dimensions D(cs)=1.87, 1.84, and 1.80 using "fractal template particles" compressed under the ratio=1.0, 2.0, and 3.0, respectively. We also discussed the possibilities of their fractal geometries in comparison with mathematical models. We concluded that the created fractal bodies were close to a Menger sponge and its modified one. Our experimental strategy allows us to design fractality of porous materials.

Journal Article↗
PubMed2002

1H-MR spectroscopy and gray matter volume of the anterior cingulate cortex in schizophrenia.

Schizophrenic and normal control subjects were examined using both H-magnetic resonance spectroscopy (MRS) and structural MR imaging, in order to accurately assess the partial volume within the spectroscopic volume of interest (VOI) in the anterior cingulate cortex. The gray matter volume within VOI correlated positively with the N-acetyl-aspartate (NAA) to choline (Cho) ratio in schizophrenics only, not in controls. Schizophrenic patients had a reduced NAA/Cho ratio and an elevated Cho/creatine ratio compared to controls after the partial volume effect was eliminated. There was a significant negative correlation between the NAA/Cho ratio and the severity of blunted affect symptom in schizophrenics. These results provide further support to the idea that the measures of H-MRS indicate not only neuronal loss but also neuronal dysfunction in schizophrenia.

Adult↗
PubMed2001

Stable colloidal dispersions of fullerenes in polar organic solvents.

Colloidal dispersions of C60 and C70 were prepared by simply mixing a fullerene solution in a good solvent with a poor polar organic solvent for fullerenes. The process was very easy and fast and the formation of particles with average diameter in the colloidal range was detected immediately after the components were mixed. The formation and the properties of the fullerene particles were studied mainly with dynamic light scattering and high-resolution transmission electron microscopy. The most interesting findings are the long-term colloid stability of the samples in the absence of any stabilizers, the relatively narrow size distribution, and the different average sizes of the particles formed by C60, C70, and their mixtures. The influence of various factors such as fullerene concentration, mixing procedure, solvent properties, and C60/C70 ratio was investigated. It is shown that the smaller particles are formed when the total fullerene concentration in the good solvent is decreased and that the fullerene particles have crystalline structure. The measured negative values for the electrophoretic mobility of the particles suggest that fullerene dispersions in polar organic solvents are stabilized by repulsive electrostatic interactions.

Journal Article↗
PubMed2001

ATP-binding cassette transporter-1 induces rearrangement of actin cytoskeletons possibly through Cdc42/N-WASP.

Positional cloning approaches revealed that Tangier disease (TD), a genetic high density lipoprotein deficiency, is associated with mutations in the ATP-binding cassette transporter-1 (ABCA1) gene. However, the biological function of ABCA1 is still not fully investigated. Recently, we have reported that the cells from the patients with TD had abnormal actin cytoskeletons in association with decreased expression of Cdc42, a member of RhoGTPases family. In the present study, we have found that actin cytoskeletons were altered in HEK293 cells transfected with human ABCA1 (hABCA1) cDNA. Cells expressing hABCA1 were divided into the following two groups by the distinct morphology with altered actin cytoskeletons: one had increased formation of filopodia (designated as Type I) and the other had long protrusions (designated as Type II). Type I cells had morphology similar to that of cells transfected with dominant active form of Cdc42 (Cdc42-DA, V12Cdc42Hs-DA). Type II cells had morphology similar to that of cells transfected with neural Wiskott-Aldrich Syndrome Protein (N-WASP),one of the established downstream effector molecules of Cdc42. We have obtained the data showing a possible pathway of ABCA1/Cdc42/N-WASP by the following experiments. Introduction of mutant of Cdc42 (dominant negative form of Cdc42, N17Cdc42Hs-DN) and N-WASP (N-WASP lacking verprolin homology domain, N-WASPDeltaVPH), both of which are supposed to have potential to inhibit rearrangement of actin cytoskeletons, significantly inhibited the morphological changes induced by expression of hABCA1. Immunoprecipitation study with FLAG-tagged ABCA1 (hABCA1-FLAG) revealed that Cdc42 was coimmunoprecipitated with hABCA1-FLAG. In addition, we have demonstrated possible intracellular colocalization of these two molecules in the overexpressing cells by the confocal laser microscopy. These results may suggest that hABCA1 regulates actin organization through the possible interaction with Cdc42Hs.

ATP Binding Cassette Transporter 1↗
PubMed1998

Super Water- and Oil-Repellent Surfaces Resulting from Fractal Structure.

Super water- and oil-repellent surfaces have been made utilizing the fractal structure of the solid surfaces. Super water-repellent surfaces showing a contact angle of 160 degrees for water droplets have been made of anodically oxidized aluminum surfaces treated with hydrophobic surface coupling agent (1H,1H,2H,2H-perfluorooctyltrichlorosilane). The fractal dimension of this surface was evaluated to be 2.19 by box counting fractal analysis. The anodically oxidized aluminum surface itself was superwettable for water (and also other solvents), and the surface hydrophobized with the surface coupling agent was altered to a super water-repellent surface. The super oil-repellent surfaces are also prepared by treating the same aluminum surface with fluorinated monoalkyl phosphates (1H,1H,2H,2H-perfluorodecyl- and -perfluorododecyl-phosphate). A rapeseed oil droplet having a surface tension of approximately 35 mN/m rolls around on the surface without attaching. The contact angle of the rapeseed oil on the super oil-repellent surface was 150 degrees. Most of the oils having a surface tension greater than 23 mN/m show greater contact angle than 120 degrees on the super-oil-repellent surfaces. The critical surface tension, gammac, was estimated to be 14.8 mN/m from the Zisman plot of the contact angles on the flat surface treated with 1H,1H,2H,2H-perfluorododecyl phosphate. This value is between the gammac of Teflon (18.5 mN/m) and that of -CF3 group ( approximately 6 mN/m). Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Liposome-induced release of cell membrane proteins from intact tissue epithelium.

During extraction and purification, membrane proteins very often undergo denaturation and deactivation. To overcome this problem, the authors have tried to establish a better methodology to make the study at in vivo tissue level, not at the isolated cellular level, possible and easier. This is in vivo direct exposure of animal tissue to the liposome that contains an artificial boundary lipid (D14DPC, 1,2-dimyristamido-1,2,-deoxyphosphatidylcholine). Bullfrog and rat tongues were used. To confirm the reasonableness of this methodology, several different techniques were adopted; the nerve response study, gel electrophoretic analysis, quartz crystal microbalance (QCM) measurement and the affinity gelchromatography. When the tongue was exposed to the D14DPC-containing DMPC liposome, a significant amount of membrane protein was found in the recovered liposome (this was the production of proteoliposome). The nerve response in the neurophysiological measurement to several taste stimuli, such as L-alanine, L-leucine, sucrose and quinine hydrochloride significantly decreased when the tongue was exposed to the same liposome. These phenomena were common to both bullfrog and rat tongues. The nerve response to the stimulation with L-alanine was the most remarkably affected in the liposomal treatment. Therefore, the L-alanine-binding protein was focused upon to confirm the reasonableness of the QCM measurement and the affinity gelchromatography. The D14DPC-containing proteoliposome always showed significant binding to both the L-alanine affinity gel and the L-alanine-conjugated QCM. The results revealed that membrane proteins can be directly and effectively released, even from intact animal tissue epithelium, using the artificial boundary lipid-containing liposome.

Animals↗
PubMed1998

A novel monoclonal antibody that recognizes apical membrane of frog taste cells.

We established a hybridoma clone 1N1 that produced a monoclonal antibody to stain the apical portion of frog taste cells, by directly immunizing taste discs of the bullfrog (Rana catesbeiana) without any dispersion procedure of the taste organ. The antibody stained discrete regions on the surface of the taste discs, but did not stain the epithelium sheet of the tongue devoid of taste discs. The antibody stained approximately 93% of the taste discs tested (172/184) derived from nine frogs, showing that distribution of the antigen was common to most of the taste discs. The following observations strongly suggested that the antibody recognized a certain antigen on the apical membrane of the taste cells. (i) The antibody selectively stained cross points of intermucus areas on the surface of the taste disc. Neither the mucus cells nor the wing cells that mainly cover the surface were stained with the antibody. (ii) Dispersed taste cells were prepared by calcium ion chelating and subsequently by collagenase treatment to avoid digestion of the antigen. The antibody stained the apical end of the taste cells.

Animals↗
PubMed1994

Taste receptor proteins directly extracted by liposome from intact epithelium of bullfrog tongue.

This work first provides that epithelial membrane proteins can be directly transferred from animal intact tissue to liposome. Bullfrog tongue was treated with a specially modified liposome that contains an artificial boundary lipid. Glossopharyngeal nerve responses of the treated tongue were then measured to five taste stimuli (NH4Cl, L-Ala, sucrose, L-Leu, and quinine hydrochloride). The liposomal treatment caused remarkable changes of the taste nerve responses. Gel electrophoretic analysis of the treated liposome revealed that the direct transfer of proteins, likely taste receptor, certainly occurred from the tongue epithelium to the liposome.

Animals↗
PubMed1986

Differential scanning calorimetric studies on the melting behavior of water in stratum corneum.

The melting behavior of water in human stratum corneum (s. corneum) has been studied by using differential scanning calorimetry (DSC) in the temperature range from -40 degrees to 20 degrees C. The DSC thermogram was analyzed in terms of the amount of bound water and the melting temperature of water in s. corneum. Extraction of the s. corneum with the mixed solvent of chloroform: methanol (2:1, v/v) or 0.5% sodium dodecyl sulfate aqueous solution decreased the bound water content, whereas extraction with water did not change the bound water content. The melting temperature of water in the s. corneum was lowered as the water contents decreased. Extraction of the water-soluble components from the s. corneum increased the melting temperature of water when the water contents were constant. The results suggest that 20-30% of water in the s. corneum is bound water interacting strongly with the protein or lipids in the s. corneum, and the excess of water over the bound water content is unbound water solubilizing the water-soluble components such as amino acids and urea in the s. corneum. The thermodynamic theory for freezing-point depression is favorably applied to the melting temperature change of the unbound water, which implies that the water-soluble components are present as an aqueous solution in the s. corneum. Measurements of the melting-point depression of water in s. corneum provide us the quantitative information on the amount of water-soluble components in the s. corneum. This technique is a sensitive and useful tool to evaluate the hydration behavior of s. corneum.

Calorimetry↗
PubMed1980

[Clinical evaluation of cefamandole on urinary tract and genital organ infections (author's transl)].

Ten patients suffering from genital organ infections, urinary tract infections and symptomless bacteriuria were treated with cefamandole (CMD). CMD was administered intravenously and drip infusion at a dosage of 4.0 g/day for 4 approximately 10 days. Clinical results obtained were as follows: Of 6 patients with genital organ infections, excellent responses were seen in 2 patients, good responses in 4 patients. Of 3 patients with urinary tract infections, excellent responses were seen in 2 patients, and good response in 1 patient. The overall efficacy rate was 100%. In the cases of urinary tract infections and symptomless bacteriuria, 3 strains of E. coli and 1 strain of Streptococcus faecalis disappeared. On the other hand, in genital organ infections, we had no bacterial findings. No significant reaction was observed in clinical laboratory findings of hemogram or in test on renal and hepatic functions, except slight transient leukopenia observed in 1 patient.

Adult↗
PubMed1975

Use of octylbenzenesulfonate in place of dodecyl sulfate in SDS-polyacrylamid gel electrophoresis.

Sodium n-octylbenzene-p-sulfonate was successfully used in place of sodium dodecyl sulfate in SDS-polyacrylamide gel electrophoresis. This modification of the usual technique made it possible to scan the polyacrylamide gel for the distribution of the surfactant by measurement of UV absorption. It was found that a band electrophoresed in advance of the complexes formed between protein polypeptides and the surfactant. The band could be observed even in the absence of protein polypeptide, and was ascribed to micelles derived from surfactant added in excess to the sample solution. The complexes were found to be detectable by scanning at 261 nm, usually with better sensitivity than by scanning at 280 nm. Thus, this modification of SDS-polyacrylamide gel electrophoresis is useful both to investigate what is going on in the gel during electrophoresis and to improve the sensitivity of detection by UV scanning of protein complexes.

Benzenesulfonates↗
PubMed1975

Proton magnetic resonance studies of the binding of an anionic surfactant with a benzene ring to a protein polypeptide with special reference to SDS-polyacrylamide gel electrophoresis.

The binding of an anionic surfactant to a protein polypeptide has been studied by the proton magnetic resonance (PMR) technique to form a part of our studies on the principles of SDS-polyacrylamide gel electrophoresis. Sodium 4-(p-butylphenyl) butane-1-sulfonate (CH3-(CH2)3-0-(CH2)4-SO3-Na+) was employed as an anionic surfactant, and reduced and carbosyamidomethylated (RCAM) bovine serum albumin as a typical protein polypeptide. The binding isotherm of the surfactant to RCAM bovine serum albumin was similar to that of sodium dodecyl sulfate (SDS). The surfactant could replace SDS in SDS-polyacrylamide gel electrophoresis without affecting the wellknown mode of spearation of protein bands. These results gave a sound basis for the assumption that the investigation of the complex between a surfactant with a benzene ring and RCAM bovine serum albumin would provide useful knowledge concerning the principles of SDS-polyacrylamide gel electrophoresis. Aggregation of the aromatic surfactant necessarily brings benzene rings together. A benzene ring is a strong source of the ring current effect on chemical shifts in nuclear magnetic resonance (NMR). Chemical shifts of the surfactant in NMR are, therefore, sensitive to whether the surfactant molecules are single-molecularly dissolved or aggregated. Full advantage was taken of the above fact in the present PMR study of the binding of the surfactant to RCAM bovine serum albumin. The chemical shifts of the phenyl and methyl protons both for the single-molecular and micellar aggregated states were estimated from measurements of the shifts as a function of the surfactant concentration. They shifted to a higher magnetic field on micelle formation, due to the increase of the ring current effect. Corresponding measurements for the complex between the surfactant and RCAM bovine serum albumin gave estimates of the chemical shifts of the phenyl and methyl groups of the surfactant bound to the protein polypeptide. They were found to shift to a magnetic field somewhat higher than that for the micellar state throughout the concentration range of the surfactant examined. These results strongly suggest that the surfactant molecules bind to the protein polypeptide in the form of micelle-like clusters, and that PMR of the groups are further influenced by the diagmagnetic effect of the protein polypeptide present as a core. No appreciable change in the mode of binding, corresponding to the steep increase in the amount of binding in the binding isotherm, was observed from the PMR studies. Taking the observed similarity between SDS and the aromatic surfactant in the binding and the gel electrophoresis into consideration, the present results strongly suggest that SDS also binds to protein polypeptides in the form of micelle-like clusters under the conditions of SDS-polyacrylamide gel electrophoreses, and support our "necklace model".

Benzene Derivatives↗
PubMed1975

Binding isotherms of sodium dodecyl sulfate to protein polypeptides with special reference to SDS-polyacylamide gel electrophoresis.

To clarify the mode of interaction between sodium dodecyl sulfate (SDS) and protein polypeptides with special reference to SDS-polyacrylamide gel electrophoresis, the binding of SDS to several protein polypeptides was investigated by the equilibrium dialysis technique. Each of the binding isotherms was characterized by the presence of two phases: an initial gradual increase in the amount of binding to 0.3-0.6 g/g (first phase) and a subsequent steep increase to 1.2-1.5 g/g (second phase). The binding was completed at a concentration of SDS below the critical micelle concentration. Throughout the first and second phases, the isotherms obtained were different for each kind of protein. On the basis of experiments with bovine serum albumin and ribonuclease (EC 3.1.4.22], the isotherms were profoundly affected by the method used for modification of the sulfhydryl groups. The claim of Reynolds and Tanford (Proc. Natl, Acad. Sci. U.S., 66, 1002 (1970)) that the isotherms are virtually identical for many kinds of proteins was not supported by the present data. Changes in the gross and local conformations were examined with reference to the isotherms by measurements of CD spectrum, free boundary electrophoresis, and gel filtration. The results obtained were collectively interpreted based on the model of SDS-protein polypeptide complexes proposed by the present authors (J. Biochem., 75, 309 (1974)).

Amylases↗