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ABSTRACT: Novel fluorescent dyes, thiazole-boron complexes bearing β-ketoiminate ligands, have been synthesized, and their fluorescence properties were investigated. The BF(2) complexes showed a pronounced aggregation-induced emission enhancement effect because of the restriction of C-Ph intramolecular rotation. The BPh(2) complexes showed higher fluorescence quantum yields than the corresponding BF(2) complexes, both in solution and in the solid state.
Organic Letters 08/2012; 14(17):4682-5. · 5.86 Impact Factor
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ABSTRACT: A novel fluorescence dye based on pyrazine-boron complexes bearing a β-iminoketone ligand has been synthesized by using a simple two-step reaction. Synthesized complexes exhibited fluorescence in solution (F(max): 472-604 nm) and in the solid state (F(max): 496-624 nm). These complexes showed a larger Stokes shift (3690-4900 cm(-1)) than well-known boron dipyrromethene dyes (400-600 cm(-1), in most cases).
Organic Letters 11/2011; 13(24):6544-7. · 5.86 Impact Factor
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ABSTRACT: The organocatalytic asymmetric direct aldol reaction of trifluoroacetaldehyde ethyl hemiacetal with aromatic methyl ketones in the presence of a catalytic amount of (S)-5-(pyrrolidin-2-yl)-1H-tetrazole in dichloroethane at 40 °C proceeds smoothly to produce (R)-4,4,4-trifluoro-1-aryl-3-hydroxy-1-butanones in high yields with up to 90% ee.
The Journal of Organic Chemistry 03/2011; 76(9):3545-50. · 4.45 Impact Factor
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ABSTRACT: A complete reversal of diastereoselectivity was observed for reactions of the trifluoroacetaldehyde ethyl hemiacetal with enamines and imines, derived from propiophenones, that produce 4,4,4-trifluoro-1-aryl-3-hydroxy-2-methyl-1-butanones. This process serves as the first reliable, metal-free, complementary anti- and syn-selective method to prepare 4,4,4-trifluoro-1-aryl-3-hydroxy-2-methyl-1-butanones.
The Journal of Organic Chemistry 01/2011; 76(1):285-8. · 4.45 Impact Factor
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ABSTRACT: A fluorescent dye, the pyridomethene-BF(2) complex, has been synthesized. Although pyridomethenes did not exhibit fluorescence, pyridomethene-BF(2) complexes exhibited fluorescence both in solution and in the solid state. The trifluoromethyl-substituted BF(2) complex formed a J-aggregate and showed the highest fluorescence quantum yield in the solid state among all pyridomethene-BF(2) complexes.
Organic Letters 09/2010; 12(18):4010-3. · 5.86 Impact Factor
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ABSTRACT: A fluorescent dye, the pyridomethene−BF2 complex, has been synthesized. Although pyridomethenes did not exhibit fluorescence, pyridomethene−BF2 complexes exhibited fluorescence both in solution and in the solid state. The trifluoromethyl-substituted BF2 complex formed a J-aggregate and showed the highest fluorescence quantum yield in the solid state among all pyridomethene−BF2 complexes.
08/2010;
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Masaya Iwamuro,
Toshiyuki Komaki, Yasuhiro Kubota,
Masayuki Seita,
Hironobu Kawamoto,
Takeshi Yuasa,
Javed M Shahid,
Reham A R A Hassan,
Wael A R A Hassan,
Shuhei Nakaji,
Yuriko Nishikawa,
Eisaku Kondo,
Kazuhide Yamamoto,
Naoya Kobayashi
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ABSTRACT: Definitive endoderm (DE) derived from stem cells holds potential to differentiate into hepatocytes. Stem cell therapy using those cells has potential for a treatment of liver disease. To date, various ways of inducing hepatocytes from embryonic stem (ES) cells have been reported by researchers. However, it has not been proved enough that induced pluripotent stem (iPS) cells behave in the same manner as ES cells in endoderm differentiation. The purpose of this study was to establish an efficient method to induce DE from iPS cells, through comparatively analyzing the efficacy of endoderm formation from mouse ES cells. Furthermore, the efficiency of a serum-free medium in the differentiation into DE was investigated. Mouse ES cells and iPS cells were floated in culture medium for 2 or 5 days and embryoid bodies (EB) were formed. Subsequently, DE was induced with 100 ng/ml activin A and 100 ng/ml basic fibroblast growth factor (bFGF). RT-PCR and real-time PCR analyses were carried out at each step to determine the gene expression of EB markers. The difference in cellular proliferation between serum-containing and serum-free media was examined by an MTS assay in EB and DE induction. iPS cells showed the paralleled mRNA expression to ES cells in each step of differentiation into EB, but the levels of expression of Sox17 and Foxa2 were relatively higher in ES cell-derived DE, whereas Cxcr4 expression was higher in iPS cell-derived DE. The utilization of serum-free medium for iPS cells showed significantly favorable cellular proliferation during EB formation and subsequent DE induction. Forming EB for 5 days and subsequently DE induction with activin A and bFGF with serum-free medium was an appropriate protocol in iPS cells. This may represent an important step for generating hepatocytes from iPS cells for the development of cell therapy.
Cell Transplantation 01/2010; 19(6):831-9. · 5.13 Impact Factor
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Masaya Iwamuro,
Toshiyuki Komaki, Yasuhiro Kubota,
Masayuki Seita,
Hironobu Kawamoto,
Takeshi Yuasa,
Javed M Shahid,
Reham A R A Hassan,
Wael A R A Hassan,
Shuhei Nakaji,
Yuriko Nishikawa,
Eisaku Kondo,
Kazuhide Yamamoto,
Ira J Fox,
Naoya Kobayashi
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ABSTRACT: Induced pluripotent stem (iPS) cells are pluripotent and are able to unlimitedly proliferate in vitro. This technical breakthrough in creating iPS cells from somatic cells has noteworthy implications for overcoming the immunological rejection and the ethical issues associated with the derivation of embryonic stem cells from embryos. In the current work, we present an efficient hepatic differentiation of mouse iPS cells in vitro. iPS cells were cultured free floating to induce the formation of embryoid bodies (EB) for 5 days. EB were transferred to a gelatin-coated plate and treated with 100 ng/ml activin A and 100 ng/ml basic fibroblast growth factor (bFGF) for 3 days to induce definitive endoderm. Cells were further cultured for 8 days with 100 ng/ml hepatocyte growth factor (HGF) to generate hepatocytes. Characterization was performed by RT-PCR assay. Functional analysis for albumin secretion and ammonia removal was also carried out. iPS cell-derived hepatocyte-like cells (iPS-Heps) were obtained at the end of the differentiation program. Expression levels of a gestational hepatocyte gene and lineage-specific hepatic genes intensified in iPS-Heps. The production of albumin increased in a time-dependent manner. iPS-Heps were capable of metabolizing ammonia. We present here instant hepatic differentiation of mouse iPS cells using combined 3-day treatments of activin A and bFGF with subsequent 8-day HGF. Our study will be an important step to generate hepatocytes from human iPS cells as a new source for liver-targeted cell therapies.
Cell Transplantation 01/2010; 19(6):841-7. · 5.13 Impact Factor
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ABSTRACT: Maintenance of freshly isolated porcine liver cells in vitro is limited for a short period of time. Therefore, establishment of easy handling cell lines is extremely important for in vitro study for liver cells and their possible utilization for cell differentiation and growth of stem cells. Porcine liver cells were transduced with a retroviral vector SSR#69 expressing SV40T, one of SSR#69-immortalized porcine liver cell lines, JSNK-1, was established and characterized. Morphology of JSNK-1 cells was spindle shaped. When the cells became confluent, JSNK-1 cells revealed hills-and-valleys pattern. In the presence of vitamin A, JSNK-1 cells showed big droplets inside the cytoplasm, which were positive with PAS staining. JSNK-1 cells showed the gene expression of collagen type 1α1, collagen type 1α2, FLT-1, β-actin, and SV40T. Immunostaining study revealed that JSNK-1 cells produced collagen, vimentin, and α-smooth muscle actin. JSNK-1 cells possessed the characteristics of the liver stellate cells. JSNK-1 cells produced hepatocyte growth factor (HGF) in a time-dependent manner. When cocultured with iPS cells towards the hepatic differentiation, JSNK-1 cells facilitated their hepatic differentiation in terms of albumin production. In conclusion, JSNK-1 cells would be valuable in the study of liver stellate cell pathophysiology and contribute to the optimization of hepatic differentiation of iPS cells.
Cell Transplantation 01/2010; 19(6):849-56. · 5.13 Impact Factor
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Tsuyoshi Yamamoto,
Nalú Navarro-Alvarez,
Alejandro Soto-Gutierrez,
Takeshi Yuasa,
Masaya Iwamuro, Yasuhiro Kubota,
Masayuki Seita,
Hironobu Kawamoto,
Shahid M Javed,
Eisaku Kondo,
Hirofumi Noguchi,
Satoru Kobayashi,
Shuhei Nakaji,
Naoya Kobayashi
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ABSTRACT: Liver diseases still have a high mortality even though liver transplantation has become a standard treatment. Currently, hepatocyte transplantation has been proposed as another promising strategy. One limitation is the availability of human livers as a source of hepatocytes. Because of an unlimited supply, the use of porcine hepatocytes might address this problem. Regardless of the source, once isolated hepatocytes lose specific functionality due to the loss of the natural microenvironment. For this reason, we tested the ability of a self-assembling peptide nanofiber (SAPNF) to provide a provisional three-dimensional (3D) support to interact with cells to control their function in vivo. Isolated porcine hepatocytes were embedded in SAPNF, or collagen type I and transplanted by direct injection into the splenic pulp of SCID mice suffering from acute liver failure (ALF) by 90% hepatectomy. SAPNF porcine hepatocyte transplantation produced engraftment that was far superior to that obtained using collagen and prolonged the survival of mice with ALF, in contrast with controls. An ultrastructural evaluation using transmission electron microscopy indicated extensive cell-cell communication and preservation of hepatocyte architecture. The transplanted SAPNF hepatocytes showed higher expression of albumin and PAS and lower apoptotic events assessed by TUNEL staining. Hepatocytes culture in a truly 3D network allows in vivo maintaining of differentiated functions, and once transplanted between widely divergent species can function to correct acute liver failure in mice and prolong their survival.
Cell Transplantation 01/2010; 19(6):799-806. · 5.13 Impact Factor
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Hironobu Kawamoto,
Takeshi Yuasa, Yasuhiro Kubota,
Masayuki Seita,
Hiromi Sasamoto,
Javed M Shahid,
Takahiro Hayashi,
Hiroyuki Nakahara,
Reham Hassan,
Masaya Iwamuro,
Eisaku Kondo,
Shuhei Nakaji,
Noriaki Tanaka,
Naoya Kobayashi
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ABSTRACT: Worldwide, colorectal cancer is the third most common type of cancer affecting both sexes. It has been proposed that a small subset of cancer cells (cancer stem cells) within each tumor is able to initiate tumor growth. In 2007, two research groups simultaneously identified a colon cancer stem cell population in human tumors by the use of CD133 expression. In the present study, we used a human colon cancer cell line, SW620, to analyze the cancer stem cell-like characteristics of CD133(+) cells in vitro and in vivo. In vitro, CD133(+) SW620 cells had a higher proliferative capacity, were more irradiation- and chemotherapy-resistant, and had a higher expression of β-catenin compared with CD133(-) cells. Injections of either CD133(+) or CD133(-) cells into the skin or rectal mucosa of NOD/SCID mice led to tumors; however, injection of CD133(+) cells resulted in the formation of larger tumors. Tumors derived from injections of CD133(-) cells did not contain any CD133(+) cells, whereas tumors derived from injections of CD133(+) cells did contain CD133(+) cells, suggesting self-renewing capability. However, the proportion of CD133(+) cells in the newly formed tumors in vivo was lower than the proportion of CD133(+) cells in vitro. In conclusion, the human colon cancer cell line, SW620, contains both CD133(+) and CD133(-) phenotypes, and the CD133(+) phenotype has characteristics consistent with those of cancer stem cells.
Cell Transplantation 01/2010; 19(6):857-64. · 5.13 Impact Factor
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Nalú Navarro-Alvarez,
Eisaku Kondo,
Hironobu Kawamoto,
Wael Hassan,
Takeshi Yuasa, Yasuhiro Kubota,
Masayuki Seita,
Hiroyuki Nakahara,
Takahiro Hayashi,
Yuriko Nishikawa,
Reham A R A Hassan,
Shahid M Javed,
Hirofumi Noguchi,
Shinichi Matsumoto,
Shuhei Nakaji,
Noriaki Tanaka,
Naoya Kobayashi,
Alejandro Soto-Gutierrez
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ABSTRACT: It has been proposed in human colorectal cancers (CRC) a minority subset of cancer cells within tumors able to initiate tumor growth, defined as cancer stem cells (CSC). Solid human primary colonic and its ovarian metastatic cancer tissues were collected from fresh surgical samples and subsequent xenografts were established in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. The resulting tumors were disaggregated into single-cell suspensions and a CD133(-) cell line (NANK) was newly established and analyzed by flow cytometry. Surface markers of progenitor cells were immunophenotypically analyzed, and expression of stem cell and cancer-related genes was characterized. Secreted angiogenesis-associated molecules were investigated by proteomic array technology. Finally, different numbers of NANK were implanted and their tumor-initiating properties were investigated in NOD/SCID mice. Intraperitoneal injection of NANK in NOD/SCID mice induced tumors with developing progressive peritoneal dissemination and ascites. NANK cells maintained a differentiated phenotype and reproduced the full morphologic and phenotypic heterogeneity of their parental lesions. Noticeably, NANK lacked the expression of conventional CSC markers CD133 and CD44, self-renewal genes Oct-4 and Nanog, but showed the expression of an important gastrointestinal development marker CDX-2 and BMI-1 that is essential in regulating the proliferative activity of normal and leukemic stem cells. In addition, NANK secreted high amounts of important angiogenic cytokines. These results provide a novel and extensive model in human CSC for studying the generation and maintenance of phenotypic heterogeneity in CRC.
Cell Transplantation 01/2010; 19(6):865-77. · 5.13 Impact Factor
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Hiroyuki Nakahara,
Haruo Misawa,
Takahiro Hayashi,
Eisaku Kondo,
Takeshi Yuasa, Yasuhiro Kubota,
Masayuki Seita,
Hironobu Kawamoto,
Wael A R A Hassan,
Reham A R A Hassan,
Shahid M Javed,
Masato Tanaka,
Hirosuke Endo,
Hirofumi Noguchi,
Shinichi Matsumoto,
Katsuyoshi Takata,
Yuichi Tashiro,
Shuhei Nakaji,
Toshifumi Ozaki,
Naoya Kobayashi
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ABSTRACT: Human mesenchymal stem cells (hMSCs) are multipotent stem cells found in the adult bone marrow that have the capacity to differentiate into various mesenchymal cell types. The hMSCs may provide a potential therapy to restore damaged tissues or organs of mesenchymal origin; however, a drawback is their limited life span in vitro.
We immortalized normal hMSCs with retrovirally transmitted human telomerase reverse transcriptase cDNA. One of the immortalized clones (YKNK-12) was established, and the biological characteristics were investigated in vitro and in vivo.
YKNK-12 cells were capable of differentiating adipocytes, osetoblasts, and chondrocytes. Osteogenically differentiated YKNK-12 cells produced significant levels of growth factors BMP4, BMP6, FGF6, FGF7, transforming growth factor-beta1, and transforming growth factor-beta3.. Microcomputer tomography T and soft X-ray assays showed an excellent calvarial bone healing in mice after transplantation of osteogenically differentiated YKNK-12 cells. These cells expressed human-specific osteocalcin and increased the gene expression of runt-related transcription factor 2, alkaline phosphatase, osteocalcin, and osterix in the bone regenerating area. YKNK-12 cell transplant corrected the bone defect without inducing any adverse effects.
We conclude that hMSCs immortalized by transduction with human telomerase reverse transcriptase may provide an unlimited source of cells for therapeutic use in bone regeneration.
Transplantation 09/2009; 88(3):346-53. · 4.00 Impact Factor
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Takeshi Yuasa,
Jorge D Rivas-Carrillo,
Nalú Navarro-Alvarez,
Alejandro Soto-Gutierrez, Yasuhiro Kubota,
Yasuhiko Tabata,
Teru Okitsu,
Hirofumi Noguchi,
Shinichi Matsumoto,
Shuhei Nakaji,
Noriaki Tanaka,
Naoya Kobayashi
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ABSTRACT: The development of a bioartificial pancreas (BAP) with immunoisolating fashion has been gaining attention as a new method for treating diabetes. We have been proceeding with the development of a bag-type BAP that can be easily implanted and that allows for the optional injection or rejection of cells at any time. If fibrosis develops around a BAP device, then the permeability of substances transmitted through a semipermeable membrane will decrease, thereby reducing the reactivity with glucose, so it is necessary for the material of the device to have an excellent histocompatibility. Furthermore, in order to improve the efficacy of BAP treatment, it is important to maintain an environment of ample blood flow around the device. We have created a bag-type device for BAP that is 20 x 20 mm in size and comprises two layers of membranes. We have used an EVAL membrane for the outer membrane of the two layers. The EVAL membrane is a semipermeable membrane with good insulin permeability, which functions as an immunoisolation membrane. The inner membrane consists of PAU-coated HD-PE (nonwoven material processed with polyaminourethan) and it is designed to function as a scaffold for cells. We used Lewis rats to determine whether the effectiveness of fibroblast growth factor 2 (bFGF) can be improved by concomitantly using bFGF with a capacity for blood vessel regeneration as well as bFGF immersed in a sheet of gelatin. We placed the BAP in the abdominal cavity and covered it with the greater omentum. We were able to significantly increase the blood flow and the number of new blood vessels in the tissue surrounding the BAP device by using gelatinized bFGF. There were only a few instances of fibrosis as a biological reaction to the EVAL membrane, and the infiltration of inflammatory cells was mild. There were no adverse effects related to implantation of the device. We confirmed in this study that the use of an implantable BAP device and bFGF allowed for a better blood flow around the BAP device. There were only minor instances of fibrosis and inflammation reaction around the BAP, thus indicating the BAP that we are currently developing to have an excellent histocompatibility.
Cell Transplantation 01/2009; 18(5):683-8. · 5.13 Impact Factor
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ABSTRACT: Reduction of the obtained chiral (S)- tert-butyl 2-(perfluoroalkanoyl)pyrrolidine-1-carboxylate with sodium borohydride or lithium aluminum hydride proceeded smoothly to give the corresponding (S)- tert-butyl 2-((R)-perfluoro-1-hydroxyalkyl)pyrrolidine-1-carboxylate in yields of 73-97% with excellent diastereoselectivities (up to >98% de), compared with the reduction of nonfluorinated (S)-tert-butyl 2-pentanoylpyrrolidine-1-carboxylate.
The Journal of Organic Chemistry 06/2008; 73(12):4694-7. · 4.45 Impact Factor
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ABSTRACT: Although heating 2-methoxy-2H-azepine results in a [1,5] sigmatropic hydrogen shift, heating 2-propylthio-2H-azepine results in not only a [1,5] sigmatropic hydrogen shift but also a [1,5] sigmatropic propylthio shift. Kinetic measurements reveal that migratory aptitudes increase in the order of MeO < H, PrS. These [1,5] sigmatropic shifts are discussed on the basis of ab initio DFT calculations. [reaction: see text].
Organic Letters 11/2006; 8(24):5469-72. · 5.86 Impact Factor
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Journal of Orthopaedic Science 12/2005; 10(6):634-40. · 0.84 Impact Factor
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ABSTRACT: [reaction: see text] Although the reactivity of tropylium ion with aromatic substrates is low, the reaction of azepinium ion with aromatic substrates such as benzene, phenol, furan, and thiophene resulted in the formation of 2-aryl-2H-azepine as a major product. An exceptional result in the formation of ring-contracted product was observed in the reaction with pyrrole.
Organic Letters 12/2005; 7(23):5215-8. · 5.86 Impact Factor
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Angewandte Chemie International Edition 02/2004; 43(6):736-8. · 13.45 Impact Factor
