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Toshinori Sato

Publications and source records attributed to Toshinori Sato.

18 recordsLinked to original sources
PubMed2007

Specific binding of GM1-binding peptides to high-density GM1 in lipid membranes.

The ganglioside Galbeta1-3GalNAcbeta1-4(Neu5Acalpha2-3)Galbeta1-4Glcbeta1-1'Cer (GM1) is an important receptor. We have previously identified GM1-binding peptides based on affinity selection from a random peptide library. In the present study, we determined the amino acids essential for binding GM1 and investigated the specific interaction with GM1 in the lipid membrane. Arginines and aromatic amino acids in the consensus sequence (W/F)RxL(xP/Px)xFxx(Rx/xR)xP contributed to the ability of the peptides to bind GM1. The peptide p3, VWRLLAPPFSNRLLP, having the consensus sequence, showed high affinity for GM1 with a dissociation constant of 1.2 microM. Furthermore, the density-dependent binding of p3 was investigated using mixed monolayers of GM1 and Glcbeta1-1'Cer (GlcCer). p3 binds preferentially to high-density GM1, and its interaction with GM1 was found to be cooperative based on a Hill plot. These results indicated that a lateral assembly of GM1 molecules was required for the recognition of carbohydrates by p3. The GM1-binding peptide played a role as a unique anti-GM1 probe differing from the cholera toxin B subunit or antibodies.

Amino Acid Sequence↗
PubMed2007

The distinction of underivatized monosaccharides using electrospray ionization ion trap mass spectrometry.

A convenient method for distinguishing underivatized isomeric monosaccharides has been established using electrospray ionization ion trap mass spectrometry (ESI-ITMS). Mass spectra of hexoses (glucose, galactose, and mannose), N-acetylhexosamines (N-acetylglucosamine, N-acetylgalactosamine, and N-acetylmannosamine) and hexosamines (glucosamine, galactosamine, and mannosamine) dissolved in solvent containing 1 mM ammonium acetate were obtained in the positive ion mode. Glucose was distinguished from galactose and mannose in the MS(2) spectrum of the [M+NH(4)](+) ion at m/z 198. The MS(3) spectra generated from [M+NH(4)-H(2)O-NH(3)](+) at m/z 163 showed that galactose and mannose could be distinguished by the ratio of peak intensities at m/z 145 and 127, while the three N-acetylhexosamine and hexosamine stereochemical isomers could be identified by the relative abundance ratios of product ions observed in MS(3) spectra. The investigation of MS and MS(2) spectra from complexes of these monosaccharides with Na(+) and Pb(2+) failed to distinguish these monosaccharide isomers. Therefore, multiple stage mass analysis by ESI-ITMS using either [M+NH(4)](+) or [M+H](+) was useful to distinguish between the isomers of monosaccharides.

Isomerism↗
PubMed2006

Apparent suppression of MMP-9 activity by GD1a as determined by gelatin zymography.

Gelatin zymography is widely used to detect and evaluate matrix metalloproteinase-9 (MMP-9) activity. MMP-9 transcription was previously shown to be negatively regulated by ganglioside GD1a [D. Hu, Z. Man, T. Xuan, P. Wang, T. Takaku, S. Hyuga, X.S. Yao, T. Sato, S. Yamagata, T. Yamagata, Ganglioside GD1a regulation of matrix metalloproteinase-9 (MMP-9) expression in mouse FBJ cell Lines: GD1a suppression of MMP-9 expression stimulated by PI3K-Akt and p38 though not by the Erk signaling pathway, 2006, submitted for publication.]. Zymography of MMP-9 of FBJ-M5 cells preincubated with GD1a indicated a greater decrease in activity than expected from mRNA suppression. Incubation of conditioned medium containing MMP-9 with GD1a caused MMP-9 activity to decrease. Examination was thus made to confirm that MMP-9 activity is actually suppressed and/or MMP-9 protein undergoes degradation by GD1a. GD1a was found to have no effect on MMP-9 activity and Western blots indicated GD1a not to diminish MMP-9 during electrophoresis under reducing conditions. GD1a appeared to mediate the binding of a portion of MMP-9 with certain molecules, with consequently greater molecular mass on the gel, to cause decrease in the activity of MMP-9 at the site where it would normally appear. Caution should be used in doing gelatin zymography since molecules other than GD1a may similarly work, causing decrease in MMP-9 activity in zymography.

Animals↗
PubMed2006

Gene transfer by DNA/mannosylated chitosan complexes into mouse peritoneal macrophages.

Chitosan is a biodegradable and biocompatible polymer and is useful as a non-viral vector for gene delivery. In order to deliver pDNA/chitosan complex into macrophages expressing a mannose receptor, mannose-modified chitosan (man-chitosan) was employed. The cellular uptake of pDNA/man-chitosan complexes through mannose recognition was then observed. The pDNA/man-chitosan complexes showed no significant cytotoxicity in mouse peritoneal macrophages, while pDNA/man-PEI complexes showed strong cytotoxicity. The pDNA/man-chitosan complexes showed much higher transfection efficiency than pDNA/chitosan complexes in mouse peritoneal macrophages. Observation with a confocal laser microscope suggested differences in the cellular uptake mechanism between pDNA/chitosan complexes and pDNA/man-chitosan complexes. Mannose receptor-mediated gene transfer thus enhances the transfection efficiency of pDNA/chitosan complexes.

Animals↗
PubMed2006

Hyaluronic acid and its derivative as a multi-functional gene expression enhancer: protection from non-specific interactions, adhesion to targeted cells, and transcriptional activation.

Hyaluronic acid (HA), a natural anionic mucopolysaccharide, can be deposited onto the cationic surface of DNA/polyethyleneimine (PEI) complexes to recharge the surface potential and reduce nonspecific interactions with proteins. HA can also be used as a ligand to target specific cell receptors. Furthermore, HA-coating enhanced the transcriptional activity of the plasmid/PEI complexes, probably by loosening the tight binding between DNA and PEI, which facilitated the approach of transcription factors. Amphoteric HA derivative having spermine side chains (Spn-HA) with a structure similar to HMG protein showed higher transcription-enhancing activity than HA. Plasmid/PEI/Spn-HA ternary complex exhibited 29-fold higher transgene expression efficiency than naked plasmid/PEI complexes in CHO cells.

Animals↗
PubMed2006

Ganglioside GD1a regulation of caveolin-1 and Stim1 expression in mouse FBJ cells: augmented expression of caveolin-1 and Stim1 in cells with increased GD1a content.

GD1a was previously shown responsible for regulating cell motility, cellular adhesiveness to vitronectin, phosphorylation of c-Met and metastatic ability of mouse FBJ osteosarcoma cells. To determine the particular molecules regulated by GD1a, FBJ cells were assessed for tumor-related gene expression by semi-quantitative RT-PCR. Caveolin-1 and stromal interaction molecule 1 (Stim1) expression in FBJ-S1 cells, rich in GD1a, were found to be 6 and 4 times as much, respectively, than in FBJ-LL cells devoid of GD1a. Enhanced production of caveolin-1 in protein was confirmed by Western blotting. A low-metastatic FBJ-LL cell variant, having high GD1a expression through beta1-4GalNAcT-1 (GM2/GD2 synthase) cDNA transfection (Hyuga S, et al, Int J Cancer 83: 685-91, 1999), showed enhanced production of caveolin-1 and Stim1 in mRNA and protein, compared to mock-transfectant M5. Incubation of FBJ-M5 cells with exogenous GD1a augmented the expression of caveolin-1 in mRNA and protein and Stim1 in mRNA as well. Treatment of FBJ-S1 with fumonisin B1, an inhibitor of N-acylsphinganine synthesis, for 15 days caused the complete depletion of gangliosides and suppressed the expression of caveolin-1 and Stim1. St3gal5 siRNA transfected cells showed decreased expression of caveolin-1 and Stim1 mRNA, as well as St3gal5 mRNA. These findings clearly indicate ganglioside GD1a to be involved in the regulation of the transformation suppressor genes, caveolin-1 and Stim1. Moreover, treatment with GD1a of mouse melanoma B16 cells and human hepatoma HepG2 cells brought about elevated expression of caveolin-1 and Stim1.

Animals↗
PubMed2006

Effects of hearing level on habitual sniffing in patients with cholesteatoma.

CONCLUSIONS: Quality of hearing is one of the key conditions promoting habitual sniffing associated with closing failure of the Eustachian tube and sniffing may stop with deterioration of hearing due to progression of the disease. OBJECTIVE: To examine habitual sniffing associated with closing failure of the Eustachian tube and hearing level in patients with cholesteatoma. PATIENTS AND METHODS: A total of 171 patients with middle ear cholesteatoma treated in Tohoku University Hospital (106 sides in 101 patients, 63 males and 38 females, mean age 43.3 years), and Sendai Ear Surgi Center (70 sides in 70 patients, 37 males and 33 females, mean age 42.7 years) were included. The patients were divided into two groups based on the presence or absence of habitual sniffing, and pre- and postoperative hearing was compared between the two groups. RESULTS: Habitual sniffing was not found in patients with air conduction hearing level worse than 60 dB or air-bone gap larger than 40 dB. Habitual sniffing disappeared in all patients with expanded air-bone gaps in lower frequency regions after surgery.

Adult↗
PubMed2006

Audiometry with nasally presented masking noise: novel diagnostic method for patulous eustachian tube.

OBJECTIVE: Nasal-noise masking audiometry was developed to assess the acoustic transfer function from the nasopharyngeal cavity to the middle ear via patulous eustachian tube (ET). STUDY DESIGN: Prospective. SETTING: Tertiary referral center. PATIENTS: Twenty-seven ears of 18 patients with patulous ET and 20 ears of 10 healthy subjects with no history of ear disease or complaints of aural symptoms. MAIN OUTCOME MEASURES: Audiometric measurement was conducted with and without masking noise presented in the nasal cavity. RESULTS: The masking effect of nasally presented noise caused elevation of the threshold for the tone presented in the external auditory canal. This threshold elevation was significantly greater, particularly in the lower-frequency region, in ears with patulous ET and was decreased to the normal range after obstructive treatment of the patulous ET. CONCLUSION: Nasal-noise masking audiometry is a simple and effective way to identify patulous ET.

Acoustic Stimulation↗
PubMed2005

A peptide motif recognizing a polymer stereoregularity.

A combinatorial phage display method was applied to films composed of a stereoregular polymer of methacrylates. The phage clones with selective affinity for isotactic (it) poly(methyl methacrylate) (PMMA) were isolated. Greater amounts of the phage clones bound to it-PMMA, compared to other stereoregular PMMAs. The phage expressing ELWRPTR most strongly bound to the polymer, and the selectivity was also the best. The peptide motif essential for the specific interaction with the stereoregular polymer was revealed.

Amino Acid Motifs↗
PubMed2005

Efficient sialylation on azidododecyl lactosides by using B16 melanoma cells.

Lactoside primers (dodecyl lactoside derivatives) resemble intermediates in the biosynthetic pathway of glycolipids and, therefore, act as substrates for cellular enzyme-catalyzed glycosylation. To establish the optimal condition for the bioproduction of a large amount of valuable materials containing GM3-type oligosaccharides, two kinds of lactoside primers having the azido group in different positions were synthesized and introduced into B16 melanoma cells. The saccharide chains of both primers were elongated by cells to give GM3-type oligosaccharide derivatives, which were released to the culture medium. The amount of glycosylated product from newly synthesized 2-azidododecyl beta-lactoside (primer II) was almost twice that from 12-azidododecyl beta-lactoside (primer I). The effects of seeded cell number, primer concentration, and length of incubation time on the glycosylation efficiency were also investigated. The results showed that the higher the seeded cell number, the larger the amount of sialylated products obtained. The optimum concentrations of primers I and II were found to be 200 and 100 microM, respectively. Above these concentrations, productivity and cell viability decreased. As regards the length of incubation time, the sialylated products increased linearly until 48 h, but productivity did not advance thereafter. These results represent the optimal conditions that are necessary for the mass production of GM3-type oligosaccharide using azidododecyl lactoside primers and B16 cells.

Animals↗
PubMed2005

Trans-tympanic silicone plug insertion for chronic patulous Eustachian tube.

CONCLUSION: Trans-tympanic insertion of a new silicone plug seems to be useful for controlling the distressing symptoms of patients with a chronic patulous Eustachian tube (PET). OBJECTIVE: To evaluate the effectiveness of a new silicone plug for blocking the isthmus of a PET in patients whose symptoms were resistant to other therapies for > 6 months. MATERIAL AND METHODS: The silicone plug (total length 23-25 mm; tip diameter 1.0-2.0 mm) was inserted in 44 ears of 37 patients with chronic PET. It was inserted through the tympanic orifice of the ET to obstruct the isthmus of the tube via an incision in the anterosuperior portion of the tympanic membrane. RESULTS: Insertion of the plug was possible in all except two ears, in which it failed because of a narrow tympanic orifice of the ET. In 11 ears of 10 patients, the plug was replaced by a larger one using the same approach to improve efficacy. Of the 42 ears in which the silicone plug was successfully inserted, 30 (71.4%) achieved relief from symptoms of PET without additional treatment. In > 60% of these cases, the symptoms of PET were well controlled with an aerated middle ear. The follow-up period ranged from 6 to 68 months (mean 38.9 months).

Adult↗
PubMed2004

Fluorous-tagged compound: a viable scaffold to prime oligosaccharide synthesis by cellular enzymes.

Fluorous-tagged saccharide primers could be viable scaffolds for the synthesis of oligosaccharides. This research demonstrates that a fluorine-containing saccharide derivative could actually be taken up by the cell, the saccharide chain elongated by cellular enzymes, and the elongated product released by the cells to the culture medium. A fluorous-tagged lactoside primer, 6-(perfluorohexyl)hexyl-4-O-(beta-D-galactopyranosyl)-beta-D-glucopyranoside, was chemically synthesized and introduced in mouse B16 cells to prime oligosaccharide synthesis. Uptake of the primer by B16 cells resulted in the sialylation of the terminal galactose residue to afford an oligosaccharide with the same glycan structure as ganglioside GM3. The presence of many fluorine atoms did not have any adverse effects to the cells. Moreover, the number of fluorine atoms did not pose a steric barrier and instead, their presence possibly increased the hydrophobicity of the primer and enhanced membrane permeability. This strategy of using a fluorous-tagged primer and cells can pave the way for an easier way of preparing oligosaccharides via an environment-friendly approach that eliminates the use of large amounts of organic solvents.

Animals↗
PubMed2004

Possible new assessment of patulous Eustachian tube function: audiometry for tones presented in the nasal cavity.

OBJECTIVE: To assess the acoustic transfer function of the Eustachian tube by means of audiometric measurements in order to evaluate the severity of the patulous condition. MATERIAL AND METHODS: Detection thresholds for tones presented in the nasal cavity (at the nostril) were measured in subjects with a patulous Eustachian tube (PET) and in normal subjects. RESULTS: In typical cases, these thresholds were lower in the subjects with PET and were markedly elevated to the same level as those of normal subjects by the insufflation of Lugol's solution (iodine solution). The pre- versus post-insufflation threshold differences seemed to reflect the effects of a patulous tube on the acoustic characteristics via the Eustachian tube. Based on the obtained results, sound patency via a patulous tube appeared to be dominant in lower frequency tones. CONCLUSION: The present method seems to be another easy way to assess PET.

Acoustic Stimulation↗
PubMed2003

Effects of contralateral noise on the measurement of auditory threshold.

It is well known that sound presented in the contralateral ear can elicit the activity of the olivocochlear (OC) efferent. In the present study, the effects of the addition of contralateral noise on the psychophysical measurements of auditory thresholds were investigated in human subjects with normal hearing. The results obtained in the present study indicate that the addition of contralateral noise at a level of only 20 or 30 dB sound pressure level (SPL) may cause a significant elevation of the auditory threshold in the mid-frequency area (usually 2-3 dB). When the level of contralateral noise was elevated, the elevation of the auditory threshold tended to be larger and the affected frequency area became wider. Although other factors that elevate the auditory thresholds, such as cross-talk effects and the acoustic reflex of the middle ear muscles, may be involved in the above-mentioned paradigm, especially when higher levels of contralateral noise are used, it is important to know the degree of OC-mediated threshold elevation in usual audiometric measurement.

Audiometry, Pure-Tone↗
PubMed2002

Synthesis of an ether-linked alkyl 5a-carba-beta-D-glucoside, a 5a-carba-beta-D-galactoside, a 2-acetamido-2-deoxy-5a-carba-beta-D-glucoside, and an alkyl 5a'-carba-beta-lactoside.

For the purpose of providing biologically stable building blocks for the biocombinatorial synthesis using a living cell, some ether-linked alkyl 5a-carba-beta-D-glycoside primers were prepared. The key step of the synthesis was coupling of 1-bromo-n-alkanes with the 1-OH unprotected derivatives of 5a-carba-sugar analogues of D-glucose, D-galactose, and 2-acetamido-2-deoxy-D-glucose (N-acetyl-D-glucosamine), in DMF in the presence of sodium hydride. Alternatively, alkyl carba-lactoside was synthesized by incorporation of a 5a-carba-beta-D-galactose residue into the 4-position of dodecyl beta-D-glucopyranoside. A strong and specific inhibition of beta-galactosidase (K(i) 0.67 microM, bovine liver) was found for dodecyl 5a-carba-beta-D-galactopyranoside.

Animals↗
PubMed2002

Receptor-independent augmentation of adenovirus-mediated gene transfer with chitosan in vitro.

Recombinant adenovirus is one of the most widely used viral vectors for gene delivery. This study was designed to evaluate the ability of chitosan, a cationic, linear polysaccharide composed of beta(1,4) linked glucosamine partly containing N-acetyl-glucosamine, to enhance the in vitro infectivity of adenovirus to mammalian cells. Wild type and a fiber-mutant replication-defective recombinant adenoviruses expressing beta-galactosidase were used. In the latter, an RGD peptide, the binding site for alpha(v)beta3 and alpha(v)beta5 integrin, was introduced in the fiber knob enabling adenovirus receptor-independent viral infection. Enhanced effect of chitosan on the infectivity of both adenoviruses was observed in Chinese hamster ovary cells that do not express the receptor for adenovirus with beta-galactosidase activity assay and x-gal staining. These data indicate the receptor-independent mechanism(s) for this enhancement effect. In addition, we found that pH of the culture medium, and molecular mass and concentration of chitosan are also critical factors. Thus, the highest effect was obtained with 0.1-1 microg/ml of chitosan with molecular mass of 19K and 40K in the culture medium of pH 6.4; on the other hand, the effect was negligible with the higher chitosan concentrations (10 microg/ml or more), lower or higher molecular mass (11K and 110K) of chitosan, or at pH of 7.4. Studies using several cell lines with variable levels of adenoviral infectivity revealed that this enhanced effect is evident in the cells with poor infectivity to adenovirus. Since chitosan is biocompatible and inexpensive, these data indicate that chitosan may be a potential candidate for a non-viral vector to safely increase adenoviral infectivity to mammalian cells, particularly those with poor susceptibility to adenoviral infection.

Adenoviridae↗
PubMedDate not supplied

Lactosylated chitosan for DNA delivery into hepatocytes: the effect of lactosylation on the physicochemical properties and intracellular trafficking of pDNA/chitosan complexes.

Chitosan is a useful nonviral vector for gene delivery. To make a pDNA/chitosan complex specific to hepatocytes, lactose-modified chitosan (lac-chitosan) was synthesized. When the percentage of lactose residues substituted was 8%, lac-chitosan showed excellent DNA-binding ability, good protection of DNA from nuclease, and the suppression of self-aggregation and serum-induced aggregation. Although the cellular uptake efficiency of the pDNA/lac-chitosan complex was almost the same as that of the pDNA/chitosan complex, the cell transfection efficiency of the former was greater for HepG2 cells having asialoglycoprotein receptors. Inhibitor of endocytosis such as bafilomycin A1 and nocodazole significantly reduced the transfection efficiency of the pDNA/lac-chitosan complex. Observations with a confocal laser scanning microscope indicated that the pDNA/lac-chitosan complexes traversed endocytic compartments more rapidly than the pDNA/chitosan complex. Furthermore, the pDNA/lac-chitosan complexes were delivered to the late endosome and have the advantage of delivering DNA to the perinuclear region.

Animals↗