The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Masaru Ishii - One of the best experts on this subject based on the ideXlab platform.

  • Bone and Stem Cells. Intravital Imaging of Bone marrow microenvironment
    Clinical calcium, 2014
    Co-Authors: Hiroki Mizuno, Junichi Kikuta, Masaru Ishii
    Abstract:

    Abstract Various kinds of cell types, such as osteoclasts, osteoblasts, hematopoietic cells, and mesenchymal cells, have been reported to exist in the Bone marrow and communicate with each other. Although there have been many previous studies about Bone marrow microenvironment, most of them were analyzed by conventional methods such as histological analysis and flow cytometry. These methods could not observe the dynamic cell movement in living Bone marrow. Recently rapid development of fluorescent Imaging techniques enables us to understand the cellular dynamics in vivo . That's why we have originally established an advanced Imaging system for visualizing living Bone tissues with intravital two-photon microscopy. Here we show the latest data and the detailed methodology of intravital Imaging of Bone marrow microenvironment, and also discuss its further application.

  • In vivo fluorescence Imaging of Bone-resorbing osteoclasts.
    Journal of the American Chemical Society, 2011
    Co-Authors: Toshiyuki Kowada, Masaru Ishii, Junichi Kikuta, Atsuko Kubo, Hiroki Maeda, Shin Mizukami, Kazuya Kikuchi
    Abstract:

    Osteoclasts are giant polykaryons responsible for Bone resorption. Because an enhancement or loss of osteoclast function leads to Bone diseases such as osteoporosis and osteopetrosis, real-time Imaging of osteoclast activity in vivo can be of great help for the evaluation of drugs. Herein, pH-activatable chemical probes BAp-M and BAp-E have been developed for the detection of Bone-resorbing osteoclasts in vivo. Their acid dissociation constants (pK(a)) were determined as 4.5 and 6.2 by fluorometry in various pH solutions. These pK(a) values should be appropriate to perform selective Imaging of Bone-resorbing osteoclasts, because synthesized probes cannot fluoresce intrinsically at physiological pH and the pH in the resorption pit is lowered to about 4.5. Furthermore, BAp-M and BAp-E have a bisphosphonate moiety that enabled the probes to localize on Bone tissues. The hydroxyapatite (HA) binding assay in vitro was, therefore, performed to confirm the tight binding of the probes to the Bone tissues. Our probes showed intense fluorescence at low pH values but no fluorescence signal under physiological pH conditions on HA. Finally, we applied the probes to in vivo Imaging of osteoclasts by using intravital two-photon microscopy. As expected, the fluorescence signals of the probes were locally observed between the osteoclasts and Bone tissues, that is, in resorption pits. These results indicate that our pH-activatable probes will prove to be a powerful tool for the selective detection of Bone-resorbing osteoclasts in vivo, because this is the first instance where in vivo Imaging has been conducted in a low-pH region created by Bone-resorbing osteoclasts.

  • The role of sphingosine 1-phosphate in migration of osteoclast precursors; an application of intravital two-photon microscopy
    Molecules and Cells, 2011
    Co-Authors: Taeko Ishii, Yutaka Shimazu, Issei Nishiyama, Junichi Kikuta, Masaru Ishii
    Abstract:

    Sphingosine-1-phosphate (S1P), a biologically active lysophospholipid that is enriched in blood, controls the trafficking of osteoclast precursors between the circulation and Bone marrow cavities via G protein-coupled receptors, S1PRs. While S1PR1 mediates chemoattraction toward S1P in Bone marrow, where S1P concentration is low, S1PR2 mediates chemorepulsion in blood, where the S1P concentration is high. The regulation of precursor recruitment may represent a novel therapeutic strategy for controlling osteoclast-dependent Bone remodeling. Through intravital multiphoton Imaging of Bone tissues, we reveal that the bidirectional function of S1P temporospatially regulates the migration of osteoclast precursors within intact Bone tissues. Imaging technologies have enabled in situ visualization of the behaviors of several players in intact tissues. In addition, intravital microscopy has the potential to be more widely applied to functional analysis and intervention.

  • sphingosine 1 phosphate mobilizes osteoclast precursors and regulates Bone homeostasis
    Nature, 2009
    Co-Authors: Masaru Ishii, Jackson G Egen, Frederick Klauschen, Martin Meierschellersheim, Yukihiko Saeki, Jean Vacher, Richard L Proia, Ronald N Germain
    Abstract:

    Osteoclasts are the only somatic cells with Bone-resorbing capacity and, as such, they have a critical role not only in normal Bone homeostasis (called 'Bone remodelling') but also in the pathogenesis of Bone destructive disorders such as rheumatoid arthritis and osteoporosis. A major focus of research in the field has been on gene regulation by osteoclastogenic cytokines such as receptor activator of NF-kappaB-ligand (RANKL, also known as TNFSF11) and TNF-alpha, both of which have been well documented to contribute to osteoclast terminal differentiation. A crucial process that has been less well studied is the trafficking of osteoclast precursors to and from the Bone surface, where they undergo cell fusion to form the fully differentiated multinucleated cells that mediate Bone resorption. Here we report that sphingosine-1-phosphate (S1P), a lipid mediator enriched in blood, induces chemotaxis and regulates the migration of osteoclast precursors not only in culture but also in vivo, contributing to the dynamic control of Bone mineral homeostasis. Cells with the properties of osteoclast precursors express functional S1P(1) receptors and exhibit positive chemotaxis along an S1P gradient in vitro. Intravital two-photon Imaging of Bone tissues showed that a potent S1P(1) agonist, SEW2871, stimulated motility of osteoclast precursor-containing monocytoid populations in vivo. Osteoclast/monocyte (CD11b, also known as ITGAM) lineage-specific conditional S1P(1) knockout mice showed osteoporotic changes due to increased osteoclast attachment to the Bone surface. Furthermore, treatment with the S1P(1) agonist FTY720 relieved ovariectomy-induced osteoporosis in mice by reducing the number of mature osteoclasts attached to the Bone surface. Together, these data provide evidence that S1P controls the migratory behaviour of osteoclast precursors, dynamically regulating Bone mineral homeostasis, and identifies a critical control point in osteoclastogenesis that may have potential as a therapeutic target.

Jyothi P Jagannathan - One of the best experts on this subject based on the ideXlab platform.

  • soft tissue special issue Imaging of Bone and soft tissue sarcomas in the head and neck
    Head and Neck Pathology, 2020
    Co-Authors: Ngocanh Tran, Jeffrey P Guenette, Jyothi P Jagannathan
    Abstract:

    Bone and soft tissue sarcomas of the head and neck are a heterogenous group of tumors with overlapping features. Distinguishing between the various subtypes is challenging but necessary for appropriate diagnosis and management. The purpose of this article is to discuss the role of Imaging in evaluating head and neck tumors, provide a general radiographic approach in differentiating between benign versus malignant lesions and give examples of selected subtypes of Bone and soft tissue sarcomas in the head and neck with classic or pathognomonic Imaging findings.

G. Scott Stacy - One of the best experts on this subject based on the ideXlab platform.

  • Imaging of Bone and soft tissue tumors.
    Radiologic clinics of North America, 2011
    Co-Authors: G. Scott Stacy
    Abstract:

    ic .th ec li ni cs .c om The diagnosis of Bone and soft tissue neoplasms is often a challenge for physicians. Primary Bone and soft tissue malignancies are relatively rare, and hence, most radiologists do not encounter these tumors with enough frequency to allow the development of a sense of familiarity. Orthopedic surgeons and pathologists are typically in a similar predicament and often rely on the radiologist to help determine the true nature of amusculoskeletal tumor, and on occasion to provide appropriate therapy (eg, via percutaneous ablative procedures). The “team approach” to diagnosis and management of Bone and soft tissue tumors is paramount to a successful outcome for the patient. The nomenclature of tumors, particularly soft tissue tumors, is vast and can be confusing, and not infrequently changes based on recent developments in histologic and genetic typing. Furthermore, there are countless “pseudotumors” that mimic Bone and soft tissue neoplasms, confounding diagnosis. Many primary Bone tumors occur in children, resulting in additional apprehension. As with tumors occurring in other parts of the body, analysis of musculoskeletal neoplasms requires a fundamental knowledge of the different varieties of tumors and tumor-like lesions, as well as a systematic approach to their evaluation. Imaging is a component of theworkup of all Bone tumors and most soft tissue tumors, with the exception of some superficial lesions. The radiograph remains the procedure of choice for initial Imaging of Bone lesions, but advances in Imaging modalities during the past few decades have allowed amazing progress in the diagnosis,

F. Peyrin - One of the best experts on this subject based on the ideXlab platform.

  • Label-free Imaging of Bone multiscale porosity and interfaces using third-harmonic generation microscopy
    Scientific Reports, 2017
    Co-Authors: Rachel Genthial, F. Peyrin, Emmanuel Beaurepaire, Marie-claire Schanne-klein, Delphine Farlay, Cécile Olivier, Yohann Bala, Georges Boivin, Jean-claude Vial, Delphine Débarre
    Abstract:

    Interfaces provide the structural basis of essential Bone functions. In the hierarchical structure of Bone tissue, heterogeneities such as porosity or boundaries are found at scales ranging from nanometers to millimeters, all of which contributing to macroscopic properties. To date, however, the complexity or limitations of currently used Imaging methods restrict our understanding of this functional integration. Here we address this issue using label-free third-harmonic generation (THG) microscopy. We find that the porous lacuno-canalicular network (LCN), revealing the geometry of osteocytes in the Bone matrix, can be directly visualized in 3D with submicron precision over millimetric fields of view compatible with histology. THG also reveals interfaces delineating volumes formed at successive remodeling stages. Finally, we show that the structure of the LCN can be analyzed in relation with that of the extracellular matrix and larger-scale structures by simultaneously recording THG and second-harmonic generation (SHG) signals relating to the collagen organization.

  • Three-dimensional X-Ray Imaging of Bone microdamage in Bone tissue
    2017
    Co-Authors: F. Peyrin, M. Langer, Rémy Gauthier, Hélène Follet, David Mitton
    Abstract:

    X-Ray CT Imaging is a choice technique to analyze Bone tissue at different scales. X-ray CT at the microscopic scale (µCT) has become a standard technique for the three-dimensional (3D) investigation of Bone micro-architecture. However, the three dimensional observation of Bone micro-damage remains challenging due to the small size of the damage relative to the attainable spatial resolution

  • 3D X-ray ultra-microscopy of Bone tissue
    Osteoporosis International, 2016
    Co-Authors: M. Langer, F. Peyrin
    Abstract:

    We review the current X-ray techniques with 3D Imaging capability at the nano-scale: transmission X-ray microscopy, ptychography and in-line phase nano-tomography. We further review the different ultra-structural features that have so far been resolved: the lacuno-canalicular network, collagen orientation, nano-scale mineralization and their use as basis for mechanical simulations. X-ray computed tomography at the micro-metric scale is increasingly considered as the reference technique in Imaging of Bone micro-structure. The trend has been to push towards increasingly higher resolution. Due to the difficulty of realizing optics in the hard X-ray regime, the magnification has mainly been due to the use of visible light optics and indirect detection of the X-rays, which limits the attainable resolution with respect to the wavelength of the visible light used in detection. Recent developments in X-ray optics and instrumentation have allowed to implement several types of methods that achieve Imaging that is limited in resolution by the X-ray wavelength, thus enabling computed tomography at the nano-scale. We review here the X-ray techniques with 3D Imaging capability at the nano-scale: transmission X-ray microscopy, ptychography and in-line phase nano-tomography. Further, we review the different ultra-structural features that have so far been resolved and the applications that have been reported: Imaging of the lacuno-canalicular network, direct analysis of collagen orientation, analysis of mineralization on the nano-scale and use of 3D images at the nano-scale to drive mechanical simulations. Finally, we discuss the issue of going beyond qualitative description to quantification of ultra-structural features.

  • In vivo Imaging of Bone micro-architecture in mice with 3D synchrotron radiation micro-tomography
    Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2005
    Co-Authors: S. Bayat, L. Apostol, E. Boller, T. Brochard, F. Peyrin
    Abstract:

    Abstract Micro-tomographic Imaging of Bone micro-architecture is increasingly used on wild and transgenic mice to follow effects of diseases or therapeutics. Synchrotron radiation micro-tomography (SR micro-CT) provides quantitative images at very high spatial resolution but has mainly been used in vitro. The aim of this work was to show the feasibility of SR micro-CT for assessing Bone mineral density and micro-architecture in vivo in mice. Imaging with a pixel size of 10 μm was performed on beam line ID19 at the ESRF using a special mouse holder. Two strains of mice (C3H/HeJ and C57BL/6J) were used for the experiment. First tests were performed in order to optimize the Imaging conditions with respect to dose. Then, six mice of each group were imaged at doses of 7 and 13 Gy (total scan time

  • In vivo Imaging of Bone micro-architecture in mice with 3D synchrotron radiation microtomography
    Nucl Instr Meth Phys Res A, 2005
    Co-Authors: S. Bayat, L. Apostol, E. Boller, T. Brochard, F. Peyrin
    Abstract:

    Micro-tomographic Imaging of Bone micro-architecture is increasingly used on wild and transgenic mice to follow effects of diseases or therapeutics. Synchrotron radiation micro-tomography (SR micro-CT) provides quantitative images at very high spatial resolution but has mainly been used in vitro. The aim of this work was to show the feasibility of SR micro-CT for assessing Bone mineral density and micro-architecture in vivo in mice. Imaging with a pixel size of 10 μm was performed on beam line ID19 at the ESRF using a special mouse holder. Two strains of mice (C3H/HeJ and C57BL/6J) were used for the experiment. First tests were performed in order to optimize the Imaging conditions with respect to dose. Then, six mice of each group were imaged at doses of 7 and 13 Gy (total scan time

Jeffrey P Guenette - One of the best experts on this subject based on the ideXlab platform.

  • soft tissue special issue Imaging of Bone and soft tissue sarcomas in the head and neck
    Head and Neck Pathology, 2020
    Co-Authors: Ngocanh Tran, Jeffrey P Guenette, Jyothi P Jagannathan
    Abstract:

    Bone and soft tissue sarcomas of the head and neck are a heterogenous group of tumors with overlapping features. Distinguishing between the various subtypes is challenging but necessary for appropriate diagnosis and management. The purpose of this article is to discuss the role of Imaging in evaluating head and neck tumors, provide a general radiographic approach in differentiating between benign versus malignant lesions and give examples of selected subtypes of Bone and soft tissue sarcomas in the head and neck with classic or pathognomonic Imaging findings.