The Experts below are selected from a list of 1983 Experts worldwide ranked by ideXlab platform
Ken Shida - One of the best experts on this subject based on the ideXlab platform.
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geomorphologic land classification map of the mekong delta utilizing JERS 1 sar images
Hydrological Processes, 2008Co-Authors: Shigeko Haruyama, Ken ShidaAbstract:Flood damage in the Mekong Delta is currently influenced by population growth and the expansion of farmland. The objectives of this study are to describe a method for visualizing flooded areas, classify the geomorphology of the area, and develop a flood-risk map of the Mekong Delta using Japanese earth resources satellite-1 synthetic aperture radar (JERS-1 SAR) data. JERS-1 SAR data-processing involves geo-referencing, image-noise reduction, re-sampling, and calculation of the normalized radar cross-section (NRCS) using TNTmips. Furthermore, we visualized the flooded area of the Mekong River Delta and discussed flood dynamics. The relation between NRCS and micro-geomorphology was clarified using the geomorphologic land classification map. After evaluating flood risk, we developed a flood-risk map to visualize the evaluated risk. The differences in NRCS derived from JERS-1 SAR data were calculated before and after flooding; visualization of the flooded area revealed that the difference between the two datasets was less than − 1·8 (dB). This value was determined from field investigations. We then compiled a map of the flooded area. The relation between NRCS and geomorphology was clarified based on the geomorphologic land classification map. Copyright © 2008 John Wiley & Sons, Ltd.
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flood risk evaluation of the mekong river delta utilizing JERS 1 sar images
Journal of Geography, 2006Co-Authors: Shigeko Haruyama, Ken ShidaAbstract:The Mekong delta is experiencing flood damage at a time when the population is growing and farmland is expanding. Because the Mekong River Delta is one of the important grain belts in Vietnam, planning disaster mitigation is government policy. The purposes of this study are to present a method of visualizing flooded areas, classify geomorphology, and make flood risk map using JERS-1 SAR of the Mekong River Delta. JERS 1 SAR data, including geo-reference, noise reduction, re-sampling, and calculation of Normalized Radar Cross Section (NRCS), were processed by TNTmips. The flooded area in the Mekong River Delta is visualized and flood dynamics are discussed. The relation between NRCS and micro-geomorphology was clarified by a field investigation and a geomorphologic land classification map is presented. After evaluating flood risk in four levels, a flood risk map was created by visualizing the evaluation. Differences between NRCS of JERS 1 SAR before and after a flood are calculated, and the flooded area is visualized for differences lower than - 1.8 (dB). This value (-1.8 dB) was defined by a field investigation. Flooded area maps for 1995, 1997, and 1998 were created. The relation between NRCS and geomorphology was clarified by field investigations, and a detailed geomorphologic map in the Mekong delta was created with reference to the geomorphologic land classification map.
Xiaofeng Huang - One of the best experts on this subject based on the ideXlab platform.
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fate of hers during tooth root development
Developmental Biology, 2009Co-Authors: Harold C. Slavkin, Pablo Bringas, Xiaofeng Huang, Yang ChaiAbstract:Tooth root development begins after the completion of crown formation in mammals. Previous studies have shown that Hertwig's epithelial root sheath (HERS) plays an important role in root development, but the fate of HERS has remained unknown. In order to investigate the morphological fate and analyze the dynamic movement of HERS cells in vivo, we generated K14-Cre;R26R mice. HERS cells are detectable on the surface of the root throughout root formation and do not disappear. Most of the HERS cells are attached to the surface of the cementum, and others separate to become the epithelial rest of Malassez. HERS cells secrete extracellular matrix components onto the surface of the dentin before dental follicle cells penetrate the HERS network to contact dentin. HERS cells also participate in the cementum development and may differentiate into cementocytes. During root development, the HERS is not interrupted, and instead the HERS cells continue to communicate with each other through the network structure. Furthermore, HERS cells interact with cranial neural crest derived mesenchyme to guide root development. Taken together, the network of HERS cells is crucial for tooth root development.
Weidong Tian - One of the best experts on this subject based on the ideXlab platform.
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immortalized hertwig s epithelial root sheath cell line works as model for epithelial mesenchymal interaction during tooth root formation
Journal of Cellular Physiology, 2020Co-Authors: Sicheng Zhang, Guoqing Chen, Weihua Guo, Shikai Wang, Yan Yang, Weidong TianAbstract:Hertwig's epithelial root sheath (HERS) is critical for epithelial-mesenchymal interaction (EMI) during tooth root formation. However, the exact roles of HERS in odontogenic differentiation by EMI have not been well characterized, because primary HERS cells are difficult to obtain. Immortalized cell lines constitute crucial scientific tools, while there are few HERS cell lines available. Our previous study has successfully established immortalized HERS cell lines. Here, we confirmed the phenotype of our HERS-H1 by verifying its characteristics and functions in odontogenic differentiation through EMI. The HERS-H1-conditioned medium (CM-H1) effectively enhanced odontogenic differentiation of dental papilla cells (DPCs) in vitro. Furthermore, Smad4 and p-Smad1/5/8 were significantly activated in DPCs treated with CM-H1, and this activation was attenuated by noggin. In vivo, our implanted recombinants of HERS-H1 and DPCs exhibited mineralized tissue formation and expression of Smad4, p-Smad1/5/8, and odontogenic differentiation markers. Our results indicated that HERS-H1 promoted DPCs odontoblastic differentiation via bone morphogenetic protein/Smad signaling. HERS-H1 exhibits relevant key molecular characteristics and constitutes a new biological model for basic research on HERS and the dental EMI during root development and regeneration.
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development of immortalized hertwig s epithelial root sheath cell lines for cementum and dentin regeneration
Stem Cell Research & Therapy, 2019Co-Authors: Sicheng Zhang, Guoqing Chen, Weihua Guo, Zirui Zhang, Weidong TianAbstract:Hertwig’s epithelial root sheath (HERS) is important in guiding tooth root formation by differentiating into cementoblasts through epithelial–mesenchymal transition (EMT) and inducing odontoblastic differentiation of dental papilla through epithelial–mesenchymal interaction (EMI) during the tooth root development. Thus, HERS cells are critical for cementum and dentin formation and might be a potential cell source to achieve tooth root regeneration. However, limited availability and lifespan of primary HERS cells may represent an obstacle for biological investigation and therapeutic use of tooth tissue engineering. Therefore, we constructed, characterized, and tested the functionality of immortalized cell lines in order to produce a more readily available alternative to HERS cells. Primary HERS cells were immortalized via infection with lentivirus vector containing the gene encoding simian virus 40 Large T Antigen (SV40LT). Immortalized HERS cell subclones were isolated using a limiting dilution method, and subclones named HERS-H1 and HERS-C2 cells were isolated. The characteristics of HERS-H1 and HERS-C2 cells, including cell proliferation, ability of epithelial–mesenchymal transformation and epithelial–mesenchymal interaction, were determined by CCK-8 assay, immunofluorescence staining, and real-time PCR. The cell differentiation into cementoblast-like cells or periodontal fibroblast-like cells was confirmed in vivo. And the inductive influence of the cell lines on dental papilla cells (DPCs) was also confirmed in vivo. HERS-H1 and HERS-C2 cells share some common features with primary HERS cells such as epithelial-like morphology, positive expression of CK14, E-Cadherin, and Vimentin, and undergoing EMT in response to TGF-beta. HERS-C2 cells showed the EMT characteristics and could differentiate into cementum-forming cells in vitro and generate cementum-like tissue in vivo. HERS-H1 could induce the differentiation of DPCs into odontoblasts in vitro and generation of dentin-like tissue in vivo. We successfully isolated and characterized novel cell lines representing two key features of HERS cells during the tooth root development and which were useful substitutes for primary HERS cells, thereby providing a biologically relevant, unlimited cell source for studies on cell biology, developmental biology, and tooth root regeneration.
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Development of immortalized Hertwig’s epithelial root sheath cell lines for cementum and dentin regeneration
BMC, 2019Co-Authors: Sicheng Zhang, Guoqing Chen, Weihua Guo, Zirui Zhang, Weidong TianAbstract:Abstract Background Hertwig’s epithelial root sheath (HERS) is important in guiding tooth root formation by differentiating into cementoblasts through epithelial–mesenchymal transition (EMT) and inducing odontoblastic differentiation of dental papilla through epithelial–mesenchymal interaction (EMI) during the tooth root development. Thus, HERS cells are critical for cementum and dentin formation and might be a potential cell source to achieve tooth root regeneration. However, limited availability and lifespan of primary HERS cells may represent an obstacle for biological investigation and therapeutic use of tooth tissue engineering. Therefore, we constructed, characterized, and tested the functionality of immortalized cell lines in order to produce a more readily available alternative to HERS cells. Methods Primary HERS cells were immortalized via infection with lentivirus vector containing the gene encoding simian virus 40 Large T Antigen (SV40LT). Immortalized HERS cell subclones were isolated using a limiting dilution method, and subclones named HERS-H1 and HERS-C2 cells were isolated. The characteristics of HERS-H1 and HERS-C2 cells, including cell proliferation, ability of epithelial–mesenchymal transformation and epithelial–mesenchymal interaction, were determined by CCK-8 assay, immunofluorescence staining, and real-time PCR. The cell differentiation into cementoblast-like cells or periodontal fibroblast-like cells was confirmed in vivo. And the inductive influence of the cell lines on dental papilla cells (DPCs) was also confirmed in vivo. Results HERS-H1 and HERS-C2 cells share some common features with primary HERS cells such as epithelial-like morphology, positive expression of CK14, E-Cadherin, and Vimentin, and undergoing EMT in response to TGF-beta. HERS-C2 cells showed the EMT characteristics and could differentiate into cementum-forming cells in vitro and generate cementum-like tissue in vivo. HERS-H1 could induce the differentiation of DPCs into odontoblasts in vitro and generation of dentin-like tissue in vivo. Conclusions We successfully isolated and characterized novel cell lines representing two key features of HERS cells during the tooth root development and which were useful substitutes for primary HERS cells, thereby providing a biologically relevant, unlimited cell source for studies on cell biology, developmental biology, and tooth root regeneration
Shigeko Haruyama - One of the best experts on this subject based on the ideXlab platform.
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geomorphologic land classification map of the mekong delta utilizing JERS 1 sar images
Hydrological Processes, 2008Co-Authors: Shigeko Haruyama, Ken ShidaAbstract:Flood damage in the Mekong Delta is currently influenced by population growth and the expansion of farmland. The objectives of this study are to describe a method for visualizing flooded areas, classify the geomorphology of the area, and develop a flood-risk map of the Mekong Delta using Japanese earth resources satellite-1 synthetic aperture radar (JERS-1 SAR) data. JERS-1 SAR data-processing involves geo-referencing, image-noise reduction, re-sampling, and calculation of the normalized radar cross-section (NRCS) using TNTmips. Furthermore, we visualized the flooded area of the Mekong River Delta and discussed flood dynamics. The relation between NRCS and micro-geomorphology was clarified using the geomorphologic land classification map. After evaluating flood risk, we developed a flood-risk map to visualize the evaluated risk. The differences in NRCS derived from JERS-1 SAR data were calculated before and after flooding; visualization of the flooded area revealed that the difference between the two datasets was less than − 1·8 (dB). This value was determined from field investigations. We then compiled a map of the flooded area. The relation between NRCS and geomorphology was clarified based on the geomorphologic land classification map. Copyright © 2008 John Wiley & Sons, Ltd.
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the technique of inundation area extraction and accuracy assessment using JERS 1 sar l band
Journal of The Japan Society of Photogrammetry and Remote Sensing, 2007Co-Authors: Takeshi Ito, Shigeko Haruyama, Seiichiro OketaniAbstract:In this research, the technique of determining threshold value in the threshold value method was presented by using JERS-1 SAR (L-band) data, and the accuracy of extracted inundation area based on the threshold was assessed the GrandTruth result and optical sensor OPS (VNIR) . The mis-distinguished area was clarified.As a result, it was clarified that the technique of determining threshold value presented by this research is effective, and the overall accuracy and κ statistics of inundation area for extracted by using JERS-1 SAR was 88.0% or more and 0.61 or more, respectively. Moreover, the inundation area extracted by JERS-1 SAR are underestimated on the swampy area or the former channel, and overestimated on the natural levee where vegetation is growing.
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flood risk evaluation of the mekong river delta utilizing JERS 1 sar images
Journal of Geography, 2006Co-Authors: Shigeko Haruyama, Ken ShidaAbstract:The Mekong delta is experiencing flood damage at a time when the population is growing and farmland is expanding. Because the Mekong River Delta is one of the important grain belts in Vietnam, planning disaster mitigation is government policy. The purposes of this study are to present a method of visualizing flooded areas, classify geomorphology, and make flood risk map using JERS-1 SAR of the Mekong River Delta. JERS 1 SAR data, including geo-reference, noise reduction, re-sampling, and calculation of Normalized Radar Cross Section (NRCS), were processed by TNTmips. The flooded area in the Mekong River Delta is visualized and flood dynamics are discussed. The relation between NRCS and micro-geomorphology was clarified by a field investigation and a geomorphologic land classification map is presented. After evaluating flood risk in four levels, a flood risk map was created by visualizing the evaluation. Differences between NRCS of JERS 1 SAR before and after a flood are calculated, and the flooded area is visualized for differences lower than - 1.8 (dB). This value (-1.8 dB) was defined by a field investigation. Flooded area maps for 1995, 1997, and 1998 were created. The relation between NRCS and geomorphology was clarified by field investigations, and a detailed geomorphologic map in the Mekong delta was created with reference to the geomorphologic land classification map.
Yang Chai - One of the best experts on this subject based on the ideXlab platform.
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fate of hers during tooth root development
Developmental Biology, 2009Co-Authors: Harold C. Slavkin, Pablo Bringas, Xiaofeng Huang, Yang ChaiAbstract:Tooth root development begins after the completion of crown formation in mammals. Previous studies have shown that Hertwig's epithelial root sheath (HERS) plays an important role in root development, but the fate of HERS has remained unknown. In order to investigate the morphological fate and analyze the dynamic movement of HERS cells in vivo, we generated K14-Cre;R26R mice. HERS cells are detectable on the surface of the root throughout root formation and do not disappear. Most of the HERS cells are attached to the surface of the cementum, and others separate to become the epithelial rest of Malassez. HERS cells secrete extracellular matrix components onto the surface of the dentin before dental follicle cells penetrate the HERS network to contact dentin. HERS cells also participate in the cementum development and may differentiate into cementocytes. During root development, the HERS is not interrupted, and instead the HERS cells continue to communicate with each other through the network structure. Furthermore, HERS cells interact with cranial neural crest derived mesenchyme to guide root development. Taken together, the network of HERS cells is crucial for tooth root development.