33 results on '"Yoneshige A"'
Search Results
2. Elevated Hydrostatic Pressure Causes Retinal Degeneration Through Upregulating Lipocalin-2
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Yoshiki Koriyama, Satoru Ueno, Akihiko Ito, Ryuichiro Kimura, Takao Inoue, Azusa Yoneshige, Man Hagiyama, and Yasutoshi Takashima
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0301 basic medicine ,Retinal degeneration ,Intraocular pressure ,QH301-705.5 ,Hydrostatic pressure ,Retinal ganglion ,Andrology ,Cell and Developmental Biology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine ,Biology (General) ,Original Research ,iron chelator ,TUNEL assay ,Glial fibrillary acidic protein ,biology ,Chemistry ,apoptosis ,Retinal ,Cell Biology ,medicine.disease ,glaucoma ,gliosis ,030104 developmental biology ,retinal ganglion cells ,Gliosis ,biology.protein ,medicine.symptom ,030217 neurology & neurosurgery ,intraocular pressure ,Developmental Biology - Abstract
Elevation of intraocular pressure is a major risk factor for glaucoma development, which causes the loss of retinal ganglion cells (RGCs). Lipocalin 2 (Lcn2) is upregulated in glaucomatous retinae; however, whether Lcn2 is directly involved in glaucoma is debated. In this study, retinal explant cultures were subjected to increased water pressure using a two-chamber culture device, and Lcn2 protein levels were examined by immunoblotting. In situ TdT-mediated dUTP nick and labeling (TUNEL) and glial fibrillary acidic protein (GFAP) immunohistochemical assays were performed to assess apoptosis and gliosis, respectively. The neurotoxicity of Lcn2 in the retinal explant culture was determined with exogenous administration of recombinant Lcn2. The Lcn2 protein levels, percentage of TUNEL-positive cells, and GFAP-positive area were significantly higher in retinae cultured under 50 cm H2O pressure loads compared to those cultured under 20 cm H2O. We found that Lcn2 exhibited neurotoxicity in retinae at dose of 1 μg/ml. The negative effects of increased hydrostatic pressure were attenuated by the iron chelator deferoxamine. This is the first report demonstrating the direct upregulation of Lcn2 by elevating hydrostatic pressure. Modulating Lcn2 and iron levels may be a promising therapeutic approach for retinal degeneration.
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- 2021
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3. Expression of cell adhesion molecule 1 in human and murine endometrial glandular cells and its increase during the proliferative phase by estrogen and cell density
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Nobuyuki Mizuguchi, Azusa Yoneshige, Man Hagiyama, Tomoyuki Otani, Ryuichiro Kimura, Kazuhiro Morishita, Akihiro Wada, Akihiko Ito, Hiroshi Kajiyama, Fuka Takeuchi, and Naoki Shiraishi
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Adult ,medicine.drug_class ,Estrogen receptor ,General Biochemistry, Genetics and Molecular Biology ,Endometrium ,Mice ,Downregulation and upregulation ,Cell Line, Tumor ,medicine ,Animals ,Humans ,Luciferase ,General Pharmacology, Toxicology and Pharmaceutics ,Cell Proliferation ,Cell adhesion molecule ,Chemistry ,Cell Adhesion Molecule-1 ,Epithelial Cells ,Estrogens ,General Medicine ,Transfection ,Glandular Cell ,Molecular biology ,Gene Expression Regulation ,Cell culture ,Estrogen ,Female - Abstract
Aims Cell adhesion molecule 1 (CADM1) mediates interepithelial adhesion and is upregulated in crowded epithelial monolayers. This study aimed to examine CADM1 expression in the human endometrium of proliferative and secretory phases, and its transcriptional regulation in terms of estrogen stimuli and higher cellularity. Main methods CADM1 immunohistochemistry was conducted on endometrial tissues from women in their 40s and adult mice subcutaneously injected with estradiol following ovariectomy. Dual-luciferase reporter assays were conducted using human endometrial HEC-50B and HEC-1B cells and reporter plasmids harboring the human CADM1 3.4-kb promoter and its deleted and mutated forms. Cells were transfected with estrogen receptor α cDNA and reporter plasmids, and treated with estradiol before luciferase activity measurement. Key findings Immunohistochemistry revealed that CADM1 was clearly expressed on the lateral membranes of the simple columnar glandular cells in the proliferative phase, but not in the secretory phase, from both women and the mouse model. The glandular cell density increased two-fold in the proliferative phase. Reporter assays identified three Sp1-binding sites as estradiol-responsive elements in the proximal region (from −223 to −84) of the transcription start site (+1) in HEC-50B cells. When the cell culture was started at eight-fold higher cell density, the CADM1 3.4-kb promoter was transactivated at a two-fold higher level in HEC-50B cells. This cell density effect was not detected for the CADM1 2.3-kb or 1.6-kb promoter. Significance Two (proximal and distal) promoter regions are suggested to function additively to transactivate CADM1 in endometrial glandular cells that crowd in the proliferative phase.
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- 2021
4. Cell Adhesion Molecule 1 Contributes to Cell Survival in Crowded Epithelial Monolayers
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Takao Inoue, Tomoyuki Otani, Ryuichiro Kimura, Akihiko Ito, Azusa Yoneshige, and Man Hagiyama
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electroporation ,Cell Survival ,Cell ,Cell Culture Techniques ,Immunoglobulins ,Catalysis ,Article ,Cell Line ,Inorganic Chemistry ,lcsh:Chemistry ,medicine ,Animals ,Humans ,Physical and Theoretical Chemistry ,Molecular Biology ,lcsh:QH301-705.5 ,Spectroscopy ,Gene knockdown ,biology ,Cell adhesion molecule ,Chemistry ,epithelial cell ,Organic Chemistry ,apoptosis ,Cell Adhesion Molecule-1 ,neutralizing antibody ,Epithelial Cells ,General Medicine ,Epithelium ,adhesion molecule ,Computer Science Applications ,Cell biology ,Rats ,Pulmonary Alveoli ,medicine.anatomical_structure ,lcsh:Biology (General) ,lcsh:QD1-999 ,Apoptosis ,lateral membrane ,Gene Knockdown Techniques ,biology.protein ,Immunoglobulin superfamily ,Antibody ,Caco-2 Cells ,CADM1 ,Cell Adhesion Molecules ,Immunostaining - Abstract
When epithelial cells in vivo are stimulated to proliferate, they crowd and often grow in height. These processes are likely to implicate dynamic interactions among lateral membranous proteins, such as cell adhesion molecule 1 (CADM1), an immunoglobulin superfamily member. Pulmonary epithelial cell lines that express CADM1, named NCI-H441 and RLE-6TN, were grown to become overconfluent in the polarized 2D culture system, and were examined for the expression of CADM1. Western analyses showed that the CADM1 expression levels increased gradually up to 3 times in a cell density-dependent manner. Confocal microscopic observations revealed dense immunostaining for CADM1 on the lateral membrane. In the overconfluent monolayers, CADM1 knockdown was achieved by two methods using CADM1-targeting siRNA and an anti-CADM1 neutralizing antibody. Antibody treatment experiments were also done on 6 other epithelial cell lines expressing CADM1. The CADM1 expression levels were reduced roughly by half, in association with cell height decrease by half in 3 lines. TUNEL assays revealed that the CADM1 knockdown increased the proportion of TUNEL-positive apoptotic cells approximately 10 folds. Increased expression of CADM1 appeared to contribute to cell survival in crowded epithelial monolayers.
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- 2020
5. Nonmetathesis Heterocycle Formation by Ruthenium-Catalyzed Intramolecular [2 + 2] Cycloaddition of Allenamide-enes to Azabicyclo[3.1.1]heptanes
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Satoshi Shuto, Tomomi Nada, Takashi Matsumoto, Yasuhiro, Yusuke Yoneshige, Mitsuhiro Arisawa, and Hiromichi Fujioka
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Heterocycle formation ,010405 organic chemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Metathesis ,01 natural sciences ,Medicinal chemistry ,Catalysis ,Cycloaddition ,0104 chemical sciences ,Ruthenium ,chemistry.chemical_compound ,chemistry ,Intramolecular force ,Organic chemistry ,Carbene - Abstract
We have developed a novel nonmetathesis reaction, namely, ruthenium-catalyzed intramolecular [2 + 2] cycloaddition of allenamide-enes, to give heterocycles (i.e., azabicyclo[3.1.1]heptanes). This is the first example of [2 + 2] cycloaddition using a ruthenium carbene catalyst. The reaction proceeds at room temperature, but not under thermal or radical conditions.
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- 2016
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6. Early Gene Expression Profile in Retinal Ganglion Cell Layer After Optic Nerve Crush in Mice
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Satoru Ueno, Azusa Yoneshige, Man Hagiyama, Yoshikazu Shimomura, Akihiko Ito, and Yoshiki Koriyama
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0301 basic medicine ,Male ,Retinal Ganglion Cells ,genetic structures ,Nerve Crush ,Apoptosis ,Biology ,Real-Time Polymerase Chain Reaction ,03 medical and health sciences ,chemistry.chemical_compound ,Mice ,Lipocalin-2 ,Gene expression ,medicine ,Animals ,Ganglion cell layer ,Oligonucleotide Array Sequence Analysis ,ATF3 ,Retina ,Activating Transcription Factor 3 ,Retinal ,Immunohistochemistry ,eye diseases ,Cell biology ,Gene expression profiling ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,medicine.anatomical_structure ,Retinal ganglion cell ,chemistry ,TWEAK Receptor ,Optic Nerve Injuries ,Optic nerve ,sense organs ,Transcriptome - Abstract
Purpose Optic nerve crush (ONC) induces retinal ganglion cell (RGC) death, which causes vision loss in glaucoma. To investigate early events leading to apoptosis of RGCs, we performed gene expression analysis of injured retinas in the period before RGC loss. Methods The temporal changes of gene profiles at 0, 1, and 4 days after ONC were determined by DNA microarray. To verify the gene expression changes in RGCs, we enriched RGCs by laser-captured microdissection and performed real-time RT-PCR of 14 selected genes. In situ localization study was performed by immunohistochemistry. Results At 1 day and 4 days after ONC, 1423 and 2010 retinal genes were changed compared with 0 day, respectively; these genes were mainly related to apoptotic process, immune process, regulation of cell cycle, and ion transport. RT-PCR analysis revealed that expression levels of Activating transcription factor 3 (Atf3), Lipocalin 2 (Lcn2), and tumor necrosis factor receptor superfamily member 12a (Tnfrsf12a) were remarkably changed in RGC-enriched fraction within 4 days postcrush. Immunohistochemical analysis confirmed that all of these genes expressed highly in the ganglion cell layer of crushed retinas. Conclusions In response to ONC, the expression of apoptotic genes was stimulated soon after crush. Atf3, Lcn2, and Tnfrsf12a might be key molecules responsible for RGC loss in glaucoma.
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- 2018
7. Cell adhesion molecule-1 shedding induces apoptosis of renal epithelial cells and exacerbates human nephropathies
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Takashi Kato, Akihiko Ito, Yasutoshi Takashima, Azusa Yoneshige, and Man Hagiyama
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0301 basic medicine ,Male ,Pathology ,medicine.medical_specialty ,Physiology ,Down-Regulation ,Apoptosis ,Biology ,Blood Urea Nitrogen ,Cell Line ,03 medical and health sciences ,chemistry.chemical_compound ,medicine ,Animals ,Humans ,Diabetic Nephropathies ,Renal Insufficiency, Chronic ,Blood urea nitrogen ,Aged ,Aged, 80 and over ,Creatinine ,Nephrosclerosis ,Cell adhesion molecule ,Cell Adhesion Molecule-1 ,Epithelial Cells ,Middle Aged ,medicine.disease ,Peptide Fragments ,030104 developmental biology ,Kidney Tubules ,chemistry ,Proto-Oncogene Proteins c-bcl-2 ,Cancer research ,Disease Progression ,Female ,Rabbits ,Biomarkers ,Kidney disease ,Signal Transduction ,Research Article - Abstract
Chronic kidney disease (CKD) is an important problem throughout the world, associated with the increase of blood urea nitrogen (BUN) and serum creatinine (sCre) and with renal tubular injuries. It is crucial to elucidate the molecular mechanisms of renal injuries to identify the new therapeutics and early diagnostic methods. We focused on cell adhesion molecule-1 (CADM1) protein. CADM1, its isoform SP4, is expressed in the epithelial cells of various tissues, including renal distal tubules, localized on the lateral cell membrane, mediates cell-cell adhesion via trans-homophilic binding, and interacts with various proteins. We previously reported that its expression was downregulated by post-proteolytic cleavage (α- and β-shedding) in pulmonary diseases. To investigate whether CADM1 α-shedding occurs in human nephropathies, we performed Western blotting and immunohistochemical analysis of specimens with arterionephrosclerosis (AS) and diabetic nephropathy (DN) from autopsied kidneys. CADM1 α-shedding was induced in AS and DN kidneys and derived from the decrease in full-length CADM1 (FL-CADM1) and increase of the COOH-terminal fragment (α-CTF). In particular, the reduced FL-CADM1 level was correlated with tubular and tubulointerstitial injuries and the increases in BUN and sCre levels. Apoptosis of renal tubular epithelial cells (TECs) was promoted in both nephropathies, and it was significantly correlated with the decrease in the FL-CADM1. Furthermore, FL-CADM1 knockdown by small interfering RNA downregulated anti-apoptotic Bcl-2 protein and promoted apoptosis of cultured renal TECs. The present study suggests that the reduction of FL-CADM1 leads to renal TEC apoptosis and could exacerbate renal tubular and tubulointerstitial injuries, which contribute to the development of CKD.
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- 2017
8. Increased ectodomain shedding of lung epithelial cell adhesion molecule 1 as a cause of increased alveolar cell apoptosis in emphysema
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Takao Inoue, Takahiro Mimae, Yoshinori Murakami, Takashi Kato, Azusa Yoneshige, Man Hagiyama, Akihiko Ito, and Morihito Okada
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Pulmonary and Respiratory Medicine ,Chronic Obstructive Pulmonary Disease ,Blotting, Western ,Immunoglobulins ,Apoptosis ,Biology ,Sensitivity and Specificity ,Severity of Illness Index ,Alveolar cells ,chemistry.chemical_compound ,Airway Epithelium ,Predictive Value of Tests ,Risk Factors ,medicine ,In Situ Nick-End Labeling ,Humans ,Immunoglobulin Fragments ,Emphysema ,TUNEL assay ,Cell adhesion molecule ,Smoking ,Cell Adhesion Molecule-1 ,Epithelial cell adhesion molecule ,respiratory system ,Intercellular Adhesion Molecule-1 ,Molecular biology ,Cell biology ,medicine.anatomical_structure ,Ectodomain ,chemistry ,Pulmonary Emphysema ,Alveolar Epithelial Cells ,Proteolysis ,Immunoglobulin superfamily ,Respiratory epithelium ,Cell Adhesion Molecules ,Biomarkers - Abstract
Rationale Alveolar epithelial cell apoptosis and protease/antiprotease imbalance based proteolysis play central roles in the pathogenesis of pulmonary emphysema but molecular mechanisms underlying these two events are not yet clearly understood. Cell adhesion molecule 1 (CADM1) is a lung epithelial cell adhesion molecule in the immunoglobulin superfamily. It generates two membrane associated C terminal fragments (CTFs), αCTF and βCTF, through protease mediated ectodomain shedding. Objective To explore the hypothesis that more CADM1-CTFs are generated in emphysematous lungs through enhanced ectodomain shedding, and cause increased apoptosis of alveolar epithelial cells. Methods and results Western blot analyses revealed that CADM1-CTFs increased in human emphysematous lungs in association with increased ectodomain shedding. Increased apoptosis of alveolar epithelial cells in emphysematous lungs was confirmed by terminal nucleotide nick end labelling (TUNEL) assays. NCI-H441 lung epithelial cells expressing mature CADM1 but not CTFs were induced to express αCTF both endogenously (by shedding inducers phorbol ester and trypsin) and exogenously (by transfection). Cell fractionation, immunofluorescence, mitochondrial membrane potentiometric JC-1 dye labelling and TUNEL assays revealed that CADM1-αCTF was localised to mitochondria where it decreased mitochondrial membrane potential and increased cell apoptosis. A mutation in the intracytoplasmic domain abrogated all three abilities of αCTF. Conclusions CADM1 ectodomain shedding appeared to cause alveolar cell apoptosis in emphysematous lungs by producing αCTF that accumulated in mitochondria. These data link proteolysis to apoptosis, which are two landmark events in emphysema.
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- 2013
9. Chemoenzymatic Synthesis of Hydrophobic Glycoprotein: Synthesis of Saposin C Carrying Complex-Type Carbohydrate
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Junko Matsuda, Masashi Hagiwara, Yoshiaki Nakahara, Yuya Asahina, Azusa Yoneshige, Hidekazu Katayama, Yuko Nakahara, Yukishige Ito, Akiharu Ueki, Hironobu Hojo, and Hiromasa Tanaka
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chemistry.chemical_classification ,Glycosylation ,Chemistry ,Stereochemistry ,Molecular Sequence Data ,Organic Chemistry ,Carbohydrates ,Glycopeptides ,Mannose ,Oxazoline ,Native chemical ligation ,Thioester ,Chemical synthesis ,Saposins ,chemistry.chemical_compound ,Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase ,Acetylglucosaminidase ,Chemical ligation ,Carrier Proteins ,Protecting group ,Hydrophobic and Hydrophilic Interactions ,Glycoproteins - Abstract
The complex-type N-linked octasaccharide oxazoline having LacNAc as the nonreducing end sugar was efficiently synthesized using the benzyl-protected LacNAc, mannose, and β-mannosyl GlcNAc units as key building blocks. To achieve a highly β-selective glycosylation with the LacNAc unit, the N-trichloroacetyl group was used for the protection of the amino group in the LacNAc unit. After complete assembly of these units and deprotection, the obtained free sugar was successfully derivatized into the corresponding sugar oxazoline. On the other hand, the N-acetylglucosaminylated saposin C, a hydrophobic lipid-binding protein, was chemically synthesized by the native chemical ligation reaction. On the basis of the previous results related to the synthesis of the nonglycosylated saposin C, the O-acyl isopeptide structure was introduced to the N-terminal peptide thioester carrying GlcNAc to improve its solubility toward aqueous organic solvents. The ligation reaction efficiently proceeded with the simultaneous O- to N-acyl shift at the O-acyl isopeptide moiety. After the removal of the cysteine-protecting group and folding, saposin C carrying GlcNAc was successfully obtained. The synthetic sugar oxazoline was then transferred to this glycoprotein using the mutant of endo-β-N-acetylglucosaminidase from Mucor hiemalis (Endo-M) (glycosynthase), and the saposin C carrying the complex-type nonasaccharide was successfully obtained.
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- 2012
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10. The intracellular domain of cell adhesion molecule 1 is present in emphysematous lungs and induces lung epithelial cell apoptosis
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Takao Inoue, Takahiro Mimae, Morihito Okada, Azusa Yoneshige, Man Hagiyama, Akihiko Ito, and Yasufumi Sato
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Cell type ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Immunoglobulins ,Apoptosis ,Respiratory Mucosa ,Biology ,γ-secretase ,Cell Line ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,medicine ,Mitochondrial apoptosis pathway ,Animals ,Humans ,Pharmacology (medical) ,Fluorescein isothiocyanate ,Molecular Biology ,Lung ,Shedding ,Biochemistry, medical ,Cell adhesion molecule ,Research ,Biochemistry (medical) ,Cell Adhesion Molecule-1 ,Epithelial Cells ,General Medicine ,Cell Biology ,respiratory system ,Nectin-like molecule 2 (Necl-2) ,Protein transfection ,Cell biology ,Protein Structure, Tertiary ,Rats ,medicine.anatomical_structure ,Ectodomain ,chemistry ,Pulmonary Emphysema ,Cell culture ,Immunoglobulin superfamily ,Tumor suppressor in lung cancer 1 (TSLC1) ,Cell Adhesion Molecules - Abstract
Background Pulmonary emphysema is characterized histologically by destruction of alveolar walls and enlargement of air spaces due to lung epithelial cell apoptosis. Cell adhesion molecule 1 (CADM1) is an immunoglobulin superfamily member expressed in lung epithelial cells. CADM1 generates a membrane-associated C-terminal fragment, αCTF, through A disintegrin- and metalloprotease-10-mediated ectodomain shedding, subsequently releasing the intracellular domain (ICD) through γ-secretase-mediated intramembrane shedding of αCTF. αCTF localizes to mitochondria and induces apoptosis in lung epithelial cells. αCTF contributes to the development and progression of emphysema as a consequence of increased CADM1 ectodomain shedding. The purpose of this study was to examine whether the ICD makes a similar contribution. Results The ICD was synthesized as a 51-amino acid peptide, and its mutant was synthesized by substituting seven amino acids and deleting two amino acids. These peptides were labeled with fluorescein isothiocyanate and were introduced into various cell lines. ICD peptide-derived fluorescence was well visualized in lung epithelial cells at the site of Mitotracker mitochondrial labeling, but was detected in locations other than mitochondria in other cell types. Mutant peptide-derived fluorescence was detected in locations other than mitochondria, even in lung epithelial cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays revealed that transduction of the ICD peptide increased the proportion of apoptotic cells 2- to 5-fold in the lung epithelial cell lines, whereas the mutant peptide did not. Abundance of the ICD was below the Western blot detection limit in emphysematous (n = 4) and control (n = 4) human lungs. However, the ICD was detected only in emphysematous lungs when it was immunoprecipitated with anti-CADM1 antibody (4/4 vs. 0/4, P = 0.029). Conclusions As the abundance of ICD molecules was sparse but present, increased CADM1 shedding appeared to contribute to the development of emphysema by generating αCTF and the ICD in lung epithelial cells. Electronic supplementary material The online version of this article (doi:10.1186/s12929-015-0173-8) contains supplementary material, which is available to authorized users.
- Published
- 2015
11. The effects of chemically synthesized saposin C on glucosylceramide-β-glucosidase
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Masanaga Muto, Hironobu Hojo, Junko Matsuda, Azusa Yoneshige, and Takashi Watanabe
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genetic structures ,Imiglucerase ,Clinical Biochemistry ,Cathepsin D ,Saposins ,law.invention ,Western blot ,law ,medicine ,Humans ,Bovine serum albumin ,chemistry.chemical_classification ,Gaucher Disease ,biology ,medicine.diagnostic_test ,Activator (genetics) ,Chemistry ,General Medicine ,Enzyme replacement therapy ,Enzyme ,Cholesterol ,Biochemistry ,Recombinant DNA ,biology.protein ,Glucosylceramidase ,medicine.drug - Abstract
Objective Saposin C (SAP-C) is an essential activator of glucosylceramide (GlcCer)-β-glucosidase (GCase), the enzyme deficient in Gaucher's disease. In this study, we investigated the effects of chemically synthesized SAP-Cs (synthetic SAP-Cs) on GCase. Methods Enzymatic assays and western blot analyses were carried out to evaluate the effects of two kinds of synthetic SAP-Cs, a non-glycosylated form and a N-glycosylated form bearing a complex type nonasaccharide, on GCase with respect to its activation, stabilization, and protection. Imiglucerase (Cerezyme) was used as the GCase. To mimic physiological conditions, GCase activity was assayed in the presence of 4-nitrobenzo-2-oxa-1,3-diazole-labeled GlcCer-containing liposomes composed of bis(monoacylglycero)phosphate, l -α-phosphatidylcholine, and cholesterol. Results GCase activities increased depending on the concentration of synthetic SAP-Cs. SAP-Cs at a concentration of 1 μM increased GCase activities significantly, by 14- to 22-fold (non-glycosylated SAP-C: 22.9 ± 0.16; nona-glycosylated SAP-C: 14.9 ± 0.19; without SAP-C: 1.05 ± 0.035 pmol/h/ng GCase). These values equaled or surpassed previously published values obtained using recombinant non-glycosylated SAP-C. Both synthetic SAP-Cs were as effective as bovine serum albumin in stabilizing GCase at 37 °C. Western blot analysis revealed that synthetic SAP-Cs specifically protected GCase from cathepsin D digestion. Conclusions The results demonstrate that these novel, chemically synthesized SAP-Cs function as activators, stabilizers, and protectors of GCase, suggesting their utility in enzyme replacement therapy in patients with Gaucher's disease.
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- 2015
12. ChemInform Abstract: Microwave-Aided One-Pot Dehydration of the Alcohol Derived from (-)-Shikimic Acid for Efficient Synthesis of Pericosines
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Koji Mizuki, Yusuke Yoneshige, Yoshihide Usami, Rikiya Kawahata, Shinya Harusawa, and Hiroki Yoneyama
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chemistry.chemical_compound ,Chemistry ,medicine ,Organic chemistry ,Alcohol ,General Medicine ,Dehydration ,Shikimic acid ,medicine.disease ,Microwave - Published
- 2015
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13. Geochemistry of Archean carbonaceous cherts deposited at immature island-arc setting in the Pilbara Block, Western Australia
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Koshi Yamamoto, S.S Binu-Lal, Masakazu Yoneshige, Hideki Wada, and Kenichiro Sugitani
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geography ,geography.geographical_feature_category ,Stratigraphy ,Archean ,Geochemistry ,chemistry.chemical_element ,Mineralogy ,Geology ,Hydrothermal circulation ,chemistry ,Volcano ,Benthic zone ,Clastic rock ,Island arc ,Carbon ,Metamorphic facies - Abstract
Archean carbonaceous meta-cherts (upper-greenschist to amphibolite facies) from the Nickol Well Unit, the Cleaverville Group (∼3.2Ga) in the Roebourne district in West Pilbara are characterized by variable Al2O3/TiO2, Zr/TiO2 and Cr/Th values and by high concentrations of carbon and some trace metals. Distribution patterns of the cherts on a newly proposed diagram (Al2O3/TiO2–element/Al2O3) indicate that concentrations of Cr, V and Ni can be explained by contributions of clastic components, whereas concentrations of Cu, Zn and Pb are much higher than those expected solely from clastic contributions. Detrital material in the cherts was derived from a wide variety of volcanic sources (mafic–ultramafic–felsic sources) consistent with the inferred geological setting of the Cleaverville Group (immature island arc setting). Excess Cu, Zn and Pb are probably from hydrothermal solutions, as suggested by positive Eu anomalies and enrichment in heavy rare-earth elements (REE) in chondrite-normalized patterns. High concentrations and light isotopic values of C (−17 to −24 per mil) in the cherts indicate that the precursory sediments were enriched in organic materials. Although it is unclear whether the organic material was derived from organic particles that settled from the ocean surface or benthic microbes, in either case, it is possible that this material played an important role in the accumulation of heavy metals (Cu, Zn and Pb) in the sediments.
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- 2002
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14. Small-angle measurements of proton-carbon nuclear reaction for secondary dose estimation
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Yusuke Koba, T. Hashiguchi, Akifumi Sonoda, Yusuke Uozumi, and H. Yoneshige
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Nuclear reaction ,Cross section (physics) ,Materials science ,Proton ,chemistry ,Exciton ,chemistry.chemical_element ,Vacuum chamber ,Atomic physics ,Carbon ,Beam (structure) ,Ion - Abstract
Aiming at better accuracy of secondary dose estimation in particle radiotherapy, we measured energy-angle double-differential cross sections of ion production reactions at small angles with a 40-MeV proton beam. The target used was natural abundant carbon, and it was placed in a special vacuum chamber, which allowed small angle measurements. Obtained data were compared with data measured previously and theoretical calculations based on the exciton model. It is the first time to determine the data of ion productions at angles smaller than 15°.
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- 2014
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15. The Juliá-Colonna Asymmetric Epoxidation Reaction of Chalcone Catalyzed by Length Defined Oligo-L-leucine: Importance of theN-Terminal Functional Group and Helical Structure of the Catalyst in the Asymmetric Induction
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Akiko Shiraki, Arata Yoneshige, Satoshi Kojima, Katsuo Ohkata, Yoshikazu Hiraga, Toshiki Manabe, and Ryukichi Takagi
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inorganic chemicals ,Chalcone ,Stereochemistry ,organic chemicals ,General Chemistry ,Degree of polymerization ,Asymmetric induction ,Catalysis ,chemistry.chemical_compound ,chemistry ,Polymerization ,Yield (chemistry) ,Moiety ,heterocyclic compounds ,Amine gas treating - Abstract
Catalysts, oligo-L-leucine, for the Julia-Colonna asymmetric epoxidation of chalcone with defined degrees of polymerization were prepared by a stepwise elongation method. The yield and enantioselectivity in the epoxidation increased with the degree of polymerization of the catalyst. The presence of an unprotected amine moiety at the N-terminus proved to be essential for high asymmetric induction. The IR characteristic absorption bands (the amide I region) of the catalysts suggested that helical structure in the catalyst is related to asymmetric induction.
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- 2000
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16. Glycosphingolipids containing 2-hydroxy fatty acid are indispensable for the long-term maintenance of axon and myelin in the nervous system
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Junko Matsuda and Azusa Yoneshige
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Pathology ,medicine.medical_specialty ,Chemistry ,Myelin sheath ,Organic Chemistry ,Leukodystrophy ,medicine ,medicine.disease ,Biochemistry - Published
- 2009
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17. Separation of benzene/cyclohexane mixtures using polyurethane–silica hybrid membranes
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Shigeharu Morooka, Katsuki Kusakabe, and Seiki Yoneshige
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Cyclohexane ,Filtration and Separation ,Permeation ,Biochemistry ,chemistry.chemical_compound ,Membrane ,chemistry ,Polymer chemistry ,medicine ,General Materials Science ,Semipermeable membrane ,Pervaporation ,Physical and Theoretical Chemistry ,Swelling ,medicine.symptom ,Benzene ,Polyurethane ,Nuclear chemistry - Abstract
Mixed sols were prepared by dissolving polyurethane (a 30 wt% solution in n -propanol, PU) and tetraethylorthosilicate (TEOS) in ethanol at PU:TEOS mass ratios of 1:2, 1:1, 2:1 and 3:1. Each of the sols was coated on a porous α-alumina support tube by the dipping method, and green membranes were heat-treated at 200°C for 1 h in an atmosphere of nitrogen. A PU membrane was also prepared with PU alone. The membranes were 5–6 μm thick. The polyurethane–silica membranes were swollen in benzene but only slightly in cyclohexane at room temperature. The degree of swelling in benzene decreased with increasing fractions of TEOS in the hybrid sols. The selectivity of benzene to cyclohexane was improved due to the suppression of swelling as a result of hybridization with TEOS. The total permeation flux and benzene/cyclohexane selectivity in the membrane prepared with a sol of PU:TEOS=1:1 were 3×10 −5 kg m −2 s −1 and 19, respectively.
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- 1998
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18. Effects of Vitamin AD3E administered at Early Stage of Fattening on Blood Components, Growing Performance and Carcass Merit in Japanese Black Cattle
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Hiroaki Ozaki, Ryuichi Yoneshige, Shunichi Kamimura, and Katsumi Hamana
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Vitamin ,medicine.medical_specialty ,chemistry.chemical_compound ,Endocrinology ,Animal science ,chemistry ,Internal medicine ,Japanese Black cattle ,medicine ,Stage (cooking) ,Biology - Published
- 1998
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19. Morphology and gas permeance of ZSM-5-type zeolite membrane formed on a porous α-alumina support tube
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Shigeharu Morooka, Seiki Yoneshige, Atsushi Murata, and Katsuki Kusakabe
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Chemistry ,technology, industry, and agriculture ,Filtration and Separation ,Butane ,Permeance ,equipment and supplies ,Molecular sieve ,Biochemistry ,chemistry.chemical_compound ,Membrane ,Chemical engineering ,Organic chemistry ,General Materials Science ,Physical and Theoretical Chemistry ,ZSM-5 ,Zeolite ,Porosity ,Layer (electronics) - Abstract
ZSM-5-type zeolite membranes were synthesized by hydrothermal reaction on the surface of a porous α-alumina support tube of 2.8 mm o.d. and 1.9 mm i.d. The average pore size of the tube was about 150 nm and the void fraction was 0.45. The silicon source was a fine silica powder and the template was a mixture of tetrapropylammoniumhydroxide and bromide. Three zones were observed in the film formed on the support tube. The top zone was a polycrystalline zeolite layer and the inner zone was a layer of α-alumina macropores partially filled with deposits. The intermediate zone was a mixture of alumina particles and deposits. The permeance of the zeolite membranes increased with decreasing thickness of zeolite layer, but permselectivity was not connected with membrane morphology. The permselectivity of n -butane to i -butane was 10–50 in the range of 30–100°C, which showed practical molecular sieving ability of the formed membranes.
- Published
- 1996
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20. Deposition of Copper from a Buffered Oxide Etchant onto Silicon Wafers
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H.G. Parks, J. Brent Hiskey, Keith K. Yoneshige, Paul J. Resnick, and Srini Raghavan
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Materials science ,Silicon ,Renewable Energy, Sustainability and the Environment ,Silicon dioxide ,Oxide ,Mineralogy ,chemistry.chemical_element ,Condensed Matter Physics ,Copper ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Electrochemistry ,Wafer ,LOCOS ,Deposition (chemistry) ,Buffered oxide etch - Abstract
The deposition of copper from a buffered oxide etchant (BOE) onto bare silicon, silicon dioxide, and patterned silicon wafers has been investigated. Deposition does not occur on surfaces of silicon dioxide, while deposition on regions of patterned silicon dioxide are observed at levels which fall between the deposition on bare silicon and silicon dioxide. The duration of a wafer rinse, which follows each immersion into a BOE solution, the silicon material as well as substrate doping do not affect the amount of deposition. The process of copper deposition from a BOE solution occurs uniformly across the surface of the wafer. The deposition on bare silicon surfaces shows an Arrhenius behavior, with two distinct activation energies: 0.40 eV (38.6 kJ mol -1 ) when the surface concentration is less than 6×10 14 Cu atom cm -2 and 0.20 eV (19.3 kJ mol -1 ) when the surface concentration is greater than 6×10 14 Cu atom cm -1 . Surface roughness is observed to increase with the extent of deposition. An electrochemical reduction is used to describe the deposition of copper onto a silicon surface from a BOE solution
- Published
- 1995
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21. UW solution improved with high anti-apoptotic activity by S-nitrosated human serum albumin
- Author
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Toshiya Kai, Takuya Shinagawa, Yu Ishima, Yuki Ohya, Yukihiro Inomata, Shinji Yoneshige, Ulrich Kragh-Hansen, Masaki Otagiri, and Toru Maruyama
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Male ,Cancer Research ,Necrosis ,Adenosine ,Physiology ,medicine.medical_treatment ,Allopurinol ,Clinical Biochemistry ,Organ Preservation Solutions ,Ischemia ,Serum albumin ,Apoptosis ,Serum Albumin, Human ,Liver transplantation ,Pharmacology ,Biochemistry ,Raffinose ,medicine ,Animals ,Humans ,Insulin ,Viaspan ,Nitric Oxide Donors ,Rats, Wistar ,Serum Albumin ,Liver injury ,Analysis of Variance ,biology ,Chemistry ,Liver Diseases ,Hep G2 Cells ,medicine.disease ,Glutathione ,Liver Transplantation ,Rats ,body regions ,Transplantation ,Liver ,Anesthesia ,Reperfusion Injury ,embryonic structures ,biology.protein ,medicine.symptom ,Reperfusion injury ,Nitroso Compounds - Abstract
S-Nitrosated human serum albumin (SNO-HSA) is useful in preventing liver ischemia/reperfusion injury, and SNO-HSA should thus be able to prevent cell injury during liver transplantation. However, the potential protective effect of SNO-HSA on a combination of cold and warm ischemia, which is obligatory when performing liver transplantation, has not been examined. Therefore, we evaluated the protective effect of SNO-HSA added to University of Wisconsin (UW) solution during cold or/and warm ischemia in situ and in vitro. First, we observed that apoptotic and necrotic cell death were increased during cold and warm ischemia, respectively. SNO-HSA, which possesses anti-apoptosis activity at low NO concentrations, can inhibit cold ischemia injury both in situ and in vitro. In contrast, SNO-HSA had no significant effect on warm liver ischemia injury which, however, can be reduced by UW solution. We also demonstrated that the cellular uptake of NO from SNO-HSA can occur during cold ischemia resulting in induction of heme oxygenase-1 within 3h of cold ischemia. Our results indicate that treatment with SNO-HSA or UW solution alone is not sufficient to inhibit liver injury during a period of both cold and warm ischemia. However, a combination of SNO-HSA and UW solution can be used to prevent the two types of ischemia. SNO-HSA-added UW solution could be very useful in transplantation, because the previously imposed constraints on preservation time can be removed. This is a great advantage in a situation as the present one with increased utilization of scarce donor organs for more recipients.
- Published
- 2012
22. Developmental changes in glycolipids and synchronized expression of nutrient transporters in the mouse small intestine
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Junko Matsuda, Naoya Kojima, Masao Miyazaki, Ayano Sasaki, Akemi Suzuki, and Azusa Yoneshige
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Ceramide ,Aging ,Amino Acid Transport Systems ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Ileum ,Weaning ,Biology ,Fatty Acid-Binding Proteins ,Biochemistry ,Sodium-Glucose Transport Proteins ,Glycosphingolipids ,chemistry.chemical_compound ,Mice ,Glycolipid ,Gene expression ,Intestine, Small ,medicine ,Animals ,RNA, Messenger ,Molecular Biology ,chemistry.chemical_classification ,Nutrition and Dietetics ,Molecular Structure ,Fatty acid ,Gene Expression Regulation, Developmental ,Membrane Transport Proteins ,Glycosphingolipid ,Immunohistochemistry ,Small intestine ,Animals, Suckling ,carbohydrates (lipids) ,Mice, Inbred C57BL ,medicine.anatomical_structure ,chemistry ,Animals, Newborn ,Receptors, LDL ,Organ Specificity ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,lipids (amino acids, peptides, and proteins) ,Chromatography, Thin Layer ,Sodium-Potassium-Exchanging ATPase ,Cotransporter - Abstract
Small intestinal epithelial cells are rich in characteristic glycosphingolipids (GSLs) that are composed of phytosphingosine and alpha-hydroxy fatty acid, but the physiological roles of GSLs in the small intestine remain unclear. Here, we report the developmental changes in GSL composition in the mouse small intestine (duodenum through ileum) and their relationship with the temporal mRNA expression of nutrient transporters. Up to 2 weeks after birth, the major GSLs were hexosylceramide (HexCer), GM3, GM1 and GD1a. After 2 weeks of age, HexCer and asialo GM1 became the major GSLs. The ceramide moiety of both HexCer and asialo GM1 was composed mainly of phytosphingosine and alpha-hydroxy fatty acid, from birth through adulthood. Immunohistochemically, GM1 localized in the cytoplasm, and asialo GM1 localized exclusively in the apical microvillous membrane of small intestinal epithelial cells. The shift from sialylated GSLs to asialo GM1 was achieved by the combinational and tissue-specific transcriptional down-regulation of GM3 synthase and GM1-beta-galactosidase at around 2 weeks of age. The temporal mRNA expression of various nutrient transporters also showed significant changes at around 2 weeks of age, including the up-regulation of the sodium/glucose cotransporter and the oligopeptide transporter, as well as the down-regulation of amino acid transporters. These synchronized changes in the mRNA expression of nutrient transporters with GSL composition during suckling-to-weanling transition suggest the contributions of GSLs to morphologic and functional development in the membrane of mouse small intestinal epithelial cells.
- Published
- 2008
23. Characterization of Hollow Cathode Performance and Thermal Behavior
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JoHanna Przybylowski, James E. Polk, Kristina Jameson, Ron M. Watkins, Lauren Cho, Dan M. Goebel, and Lance Yoneshige
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Materials science ,Ion thruster ,business.industry ,Analytical chemistry ,chemistry.chemical_element ,Lanthanum hexaboride ,Tungsten ,Temperature measurement ,Cathode ,Ion ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Optoelectronics ,Work function ,business ,Common emitter - Abstract
Hollow cathodes are one of the main life-limiting components in ion engines and Hall thrusters. Although state-of-the-art hollow cathodes have demonstrated up to 30,352 hours of operation in ground tests with careful handling, future missions are likely to require longer life, more margin and greater resistance to reactive contaminant gases. Three alternate hollow cathode technologies that exploit different emitter materials or geometries to address some of the limitations of state-of-the-art cathodes are being investigated. Performance measurements of impregnated tungsten-iridium dispenser cathodes at discharge currents of 4 to 15 A demonstrated that they have the same operating range and ion production efficiency as conventional tungsten dispenser cathodes. Temperature measurements indicated that tungsten-iridium cathodes also operate at the same emitter temperatures. They did not exhibit the expected reduction in work function at the current densities tested. Hollow cathodes with lanthanum hexaboride emitters operated over a wide current range, but suffered from lower ion production efficiency at currents below about 12.4 A because of higher insert heating requirements. Differences in operating voltages and ion production rates are explained with a simple model of the effect of cathode parameters on discharge behavior.
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- 2006
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24. Microwave-Aided One-Pot Dehydration of the Alcohol Derived from (−)-Shikimic Acid for Efficient Synthesis of Pericosines
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Hiroki Yoneyama, Shinya Harusawa, Yusuke Yoneshige, Rikiya Kawahata, Koji Mizuki, and Yoshihide Usami
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Pharmacology ,chemistry.chemical_compound ,chemistry ,Organic Chemistry ,medicine ,Organic chemistry ,Alcohol ,Dehydration ,Shikimic acid ,medicine.disease ,Microwave ,Analytical Chemistry - Published
- 2014
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25. ChemInform Abstract: The Julia-Colonna Asymmetric Epoxidation Reaction of Chalcone Catalyzed by Length Defined Oligo-L-leucine: Importance of the N-Terminal Functional Group and Helical Structure of the Catalyst in the Asymmetric Induction
- Author
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Katsuo Ohkata, Yoshikazu Hiraga, Satoshi Kojima, Arata Yoneshige, Toshiki Manabe, Ryukichi Takagi, and Akiko Shiraki
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inorganic chemicals ,Chalcone ,organic chemicals ,General Medicine ,Degree of polymerization ,Asymmetric induction ,Catalysis ,chemistry.chemical_compound ,chemistry ,Polymerization ,Yield (chemistry) ,Polymer chemistry ,Moiety ,heterocyclic compounds ,Amine gas treating - Abstract
Catalysts, oligo-L-leucine, for the Julia-Colonna asymmetric epoxidation of chalcone with defined degrees of polymerization were prepared by a stepwise elongation method. The yield and enantioselectivity in the epoxidation increased with the degree of polymerization of the catalyst. The presence of an unprotected amine moiety at the N-terminus proved to be essential for high asymmetric induction. The IR characteristic absorption bands (the amide I region) of the catalysts suggested that helical structure in the catalyst is related to asymmetric induction.
- Published
- 2000
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26. Behavioural and neurochemical effects of cholinergic and dopaminergic agonists administered into the accumbal core and shell in rats
- Author
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Naruto Yoneshige, Noriaki Koshikawa, Makiko Kitamura, and Alexander R. Cools
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Male ,medicine.medical_specialty ,Carbachol ,Quinpirole ,Dopamine ,Changes in basal ganglia-thalamocortical circuits in Parkinson's disease ,Striatum ,Nucleus accumbens ,Cholinergic Agonists ,Motor Activity ,Nucleus Accumbens ,Veranderingen in basale ganglia-thalamocorticale circuits in Parkinson's ziekte ,Cellular and Molecular Neuroscience ,Internal medicine ,Dopamine receptor D2 ,medicine ,Animals ,Drug Interactions ,Rats, Wistar ,Pharmacology ,Chemistry ,Dopaminergic ,Rats ,Endocrinology ,Dopamine receptor ,Dopamine Agonists ,2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine ,medicine.drug - Abstract
Item does not contain fulltext The first goal of this study was to investigate whether turning behaviour elicited by unilateral injections of the cholinergic agonist carbachol into the shell of the nucleus accumbens differs from the elicited by similar injections into the core of this nucleus, and to compare the behavioural effects with the known effects of such injections of the mixture of the dopamine D1 and D2 receptor agonists SKF 38393 (5 ug) and quinpirole (10 ug). The second goal was to investigate whether these injections of carbachol produce neurochemical alterations in the ventrolateral striatum that differ from simular injections of the mixture of the dopamine D1 en D2 receptor agonists into these brain regions. Injections of carbachol into the shell produced predominantly (a) contralateral circling marked by normal stepping and running in wide circles during the initial 50 min and (b) postural asymmetry during the following 75 min; similar injections into the core produced (a) contralateral pivoting, namely pathological head-to-tail turning marked by abnormal hindlimb stepping during the initial 50 min and (b) postural asymmetry during the next 75 min; The postural asymmetry seen after the carbachol injections was closely associated with the drug-induced increase in the dopamine release measured by microdialysis in the ipsilateral striatum. Injections of the mixture of dopamine agonists into the shell, but not core,also produced pivoting. These shell injections increased the dopamine release in the ipsilateral striatum, and decreased the contralateral striatum. The relative increase in the ipsilateral striatum was closely associated with the drug-induced pivoting. The data show that stimulation of cholinergic and dopaminergic receptors in the shell and core elicit effects that vary according to the subregion of the nucleus accumbens. It is concluded that the accumbens-specific, cholinergic effects are mediated via substrates that differ from those involved in the shell-specific, dopaminergic effects.
- Published
- 1999
27. Effects of YM-14673, a thyrotropin-releasing hormone analogue, injected into the shell and the core of the nucleus accumbens on production of repetitive jaw movements in rats: comparison with the effects of a dopamine D1 and D2 receptor agonist combination
- Author
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Hisako Fujioka, Naruto Yoneshige, Kazunori Adachi, Noriaki Koshikawa, and Noriya Hirose
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Agonist ,Male ,medicine.medical_specialty ,Quinpirole ,medicine.drug_class ,Movement ,Mandible ,Nucleus accumbens ,Nucleus Accumbens ,Rats, Sprague-Dawley ,Tongue ,Dopamine ,Neck Muscles ,Internal medicine ,Dopamine receptor D2 ,medicine ,Thyrotropin-Releasing Hormone Analogue ,Animals ,Receptor ,Thyrotropin-Releasing Hormone ,Injections, Intraventricular ,Mouth ,Dose-Response Relationship, Drug ,Chemistry ,Electromyography ,Masseter Muscle ,Receptors, Dopamine D2 ,Receptors, Dopamine D1 ,General Medicine ,Dipeptides ,Benzazepines ,Rats ,medicine.anatomical_structure ,Endocrinology ,Dopamine Agonists ,Azetidines ,Nucleus ,medicine.drug - Abstract
The present study examined whether the shell and the core of the nucleus accumbens play a differential role in the display of YM-14673-induced jaw movements in rats. For that purpose the effects of YM-14673 were compared to those of a SKF 82958 and quinpirole combination, a dopamine D1 and a D2 receptor agonist respectively, that is known to functionally differentiate these two subregions of the nucleus. Consistent with the previous report, bilateral injections of a mixture of SKF 82958 (5 micrograms) and quinpirole (10 micrograms) into the shell of the nucleus accumbens produced repetitive jaw movements, whereas similar injections of the mixture into the core did not induce such an effect. In contrast, there was no regional difference in the effects of YM-14673 on the production of repetitive jaw movements. Thus, both bilateral injections of YM-14673 (0.1 or 1.0 microgram) into the shell or the core produced similar repetitive jaw movements in a dose-related manner. Moreover, the pattern of oral movements induced by YM-14673 differed from that induced by the mixture of SKF 82958 and quinpirole; frequent tongue protrusions were evident in rats treated with the mixture but were not seen in YM-14673-treated rats. It therefore appears that, unlike the effects of the mixture of dopamine D1 and D2 receptor agonists, the effects of YM-14673 in the shell on the production of rat jaw movements do not differ from the effects of the compound in the core.
- Published
- 1997
28. Mechanistic Study of the Deposition of Metals from HF Solutions onto Silicon Wafers
- Author
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H.G. Parks, J. B. Hiskey, and K. Yoneshige
- Subjects
Materials science ,Metal ions in aqueous solution ,Inorganic chemistry ,Oxide ,Electrochemistry ,Redox ,law.invention ,Metal ,chemistry.chemical_compound ,Capacitor ,chemistry ,Chemical engineering ,law ,visual_art ,visual_art.visual_art_medium ,Wafer ,Leakage (electronics) - Abstract
Process chemicals in use today are quite pure, depending on the grade used but can easily be contaminated with metal ions through improper handling or storage techniques. Such metal impurities, if deposited on wafer surfaces during processing can increase reverse-bias junction leakage, degrade oxide breakdown strength and increase metal oxide semiconductor capacitor leakage which in turn can adversely affect the function of ultra large scale integrated (ULSI) circuits. Because of these device effects and since metal contamination can come from several sources it is important to know the deposition level and mechanism on Si wafers from a given process solution. HF based process solution have been investigated due to their historical use in patterning, etching, and their increased use in advanced wafer cleaning processes.Multi-contaminant experiments have been designed to study the probability of, and mechanism for deposition. It is shown that in general single element deposition is predicted by electrochemical considerations based on redox reactions, however, potential complex synergistic interactions can cause deviations from the simple theory. Specifically, Sn is shown to inhibit the deposition of Ag, and Mo does not deposit in proportion to the amount of Mo in solution, but does deposit on wafers in the presence of Cu and/or Ag. Detailed analysis of Cu and Ag from BOE and Cu from HF shows the deposition: is statistically uniform over bare Si wafers, is independent of substrate doping and rinse time, does not occur on SiO2 is linear with time (up to 25 min) and solution concentration ( up to 500 ppb), shows an Arrhenius behavior with temperature (15 - 55°C) and increases surface micro-roughness. Interpretation of these results with an Evans diagram indicates the deposition is mass transport limited, allowing a first order quantitative theoretical interpretation of the deposition process.
- Published
- 1993
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29. Influence of Polymerization Degree of Poly-L-leucine Catalyst and Substituent Effect on the Juliá-Colonna Asymmetric Epoxidation of Benzalacetophenones
- Author
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Akiko Siraki, Arata Yoneshige, Kin-ichirou Koyama, Katsuo Ohkata, Shahnaz Begum, and Ryukichi Takagi
- Subjects
Pharmacology ,Organic Chemistry ,Poly-L-leucine ,Substituent ,Epoxide ,Benzalacetophenone ,General Medicine ,Medicinal chemistry ,Degree (temperature) ,Analytical Chemistry ,Catalysis ,chemistry.chemical_compound ,Chain length ,chemistry ,Polymerization ,Yield (chemistry) ,Polymer chemistry ,Organic chemistry - Abstract
The Julia-Colonna asymmetric epoxidation reaction of substituted benzalacetophenone afforded the corresponding epoxide with high yield and high enantioselectivity, catalyzed by the specified length of poly-L-leucine (chain length n > 15). Poly-L-leucine catalysts have been prepared by the polymerization reaction of L-leucine-NCA with initiators (BnONa, n-BuNH 2 , H 2 O) and characterized by the MALDI-TOF Mass and IR analysis.
- Published
- 2004
- Full Text
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30. Photocrosslinkable polymers bearing pendant triple bonds
- Author
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Masao Kato and Yoneshige Yasuo
- Subjects
chemistry.chemical_classification ,Bearing (mechanical) ,Materials science ,chemistry ,law ,Polymer chemistry ,General Engineering ,General Materials Science ,Polymer ,Pendant group ,Triple bond ,law.invention - Published
- 1979
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31. Studies on the Constituents of Polygonaceous Plants. III
- Author
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Kiyoshi Tsukida and Michiko Yoneshige
- Subjects
Pharmacology ,Traditional medicine ,Chemistry ,Pharmaceutical Science ,POLYGONUM CUSPIDATUM - Published
- 1954
- Full Text
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32. Studies on the Constituents of Polygonaceous Plants. IV
- Author
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Junko Tsujioka, Kiyoshi Tsukida, and Michiko Yoneshige
- Subjects
Pharmacology ,Traditional medicine ,biology ,Chemistry ,Rheum undulatum ,Pharmaceutical Science ,biology.organism_classification - Published
- 1954
- Full Text
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33. [Untitled]
- Author
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Yasuo Yoneshige and Masao Kato
- Subjects
chemistry.chemical_classification ,chemistry.chemical_compound ,Type II reaction ,Ketone ,chemistry ,Methyl vinyl ketone ,Polymer chemistry ,Copolymer ,Solid-state ,Methyl methacrylate ,Photodegradation ,Styrene - Abstract
Photodegradation behavior for copolymers of styrene (St), α-methyl styrene (α-MSt) and methyl methacrylate (MMA) with methyl vinyl ketone (MVK) and phenyl vinyl ketone (PVK) in the presence of air was investigated in the solid state and in solution. Photolysis of St/MVK and St/PVK copolymers proceeded smoothly and an increase of the ketone in the copolymer resulted in an increase of the rate of degradation. Generally, the rate of degradation is faster in St/PVK copolymers than in St/MVK copolymers. It is likely that the degradation of the copolymers takes place mainly through NORRISH type II reaction. It was found that the photolysis of α-MSt/PVK copolymers was retarded considerably as compared with St/PVK copolymers. An unexpected behavior was observed in the case of MMA/MVK or MMA/PVK copolymers. These copolymers were expected to degrade with slow rates; they degraded, however, rapidly. Some experiments were done to explain this phenomenon. Das lichtinduzierte Zersetzungsverhalten von Copolymeren aus Styrol (St), α-Methylstyrol (α-MSt) und Methacrylsauremethylester (MMA) mit Methylvinylketon (MVK) und Phenylvinylketon (PVK) wurde in Gegenwart von Luft im festen Zustand und in Losung untersucht. Die Photolyse von St/MVK- oder St/PVK-Copolymeren erfolgt rasch, und mit zunehmendem Gehalt an Ketogruppen im Copolymeren steigt die Geschwindigkeit der Zersetzung. Im allgemeinen zersetzen sich St/PVK-Copolymere schneller als St/MVK-Copolymere. Die Zersetzung erfolgt wahrscheinlich hauptsachlich nach einem NORRISH-Mechanismus (Typ II). Die Photolyse von α-MSt/PVK-Copolymeren erfolgte erheblich langsamer als die von St/PVK-Copolymeren. Ein unerwartetes Verhalten zeigten MMA/MVK- und MMA/PVK-Copolymere. Diese Copolymeren zersetzten sich sehr schnell, obwohl man eine langsame Zersetzung erwartet hatte. Zur Erklarung dieses Phanomens wurden einige Experimente durchgefuhrt.
- Published
- 1973
- Full Text
- View/download PDF
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