P38 Mitogen-Activated Protein Kinase Inhibitor, FR167653, Inhibits Parathyroid Hormone Related Protein-Induced Osteoclastogenesis and Bone Resorption

p38 mitogen-activated protein kinase (MAPK) acts downstream in the signaling pathway that includes receptor activator of NF-κB (RANK), a powerful inducer of osteoclast formation and activation. We investigated the role of p38 MAPK in parathyroid hormone related protein (PTHrP)-induced osteoclastogenesis in vitro and PTHrP-induced bone resorption in vivo. The ability of FR167653 to inhibit osteoclast formation was evaluated by counting the number of tartrate-resistant acid phosphatase positive multinucleated cells (TRAP-positive MNCs) in in vitro osteoclastgenesis assays. Its mechanisms were evaluated by detecting the expression level of c-Fos and nuclear factor of activated T cells c1 (NFATc1) in bone marrow macrophages(BMMs) stimulated with sRANKL and M-CSF, and by detecting the expression level of osteoprotegerin (OPG) and RANKL in bone marrow stromal cells stimulated with PTHrP in the presence of FR167653. The function of FR167653 on bone resorption was assessed by measuring the bone resorption area radiographically and by counting osteoclast number per unit bone tissue area in calvaria in a mouse model of bone resorption by injecting PTHrP subcutaneously onto calvaria. Whole blood ionized calcium levels were also recorded. FR167653 inhibited PTHrP-induced osteoclast formation and PTHrP-induced c-Fos and NFATc1 expression in bone marrow macrophages, but not the expression levels of RANKL and OPG in primary bone marrow stromal cells treated by PTHrP. Furthermore, bone resorption area and osteoclast number in vivo were significantly decreased by the treatment of FR167653. Systemic hypercalcemia was also partially inhibited. Inhibition of p38 MAPK by FR167653 blocks PTHrP-induced osteoclastogenesis in vitro and PTHrP-induced bone resorption in vivo, suggesting that the p38 MAPK signaling pathway plays a fundamental role in PTHrP-induced osteoclastic bone resorption

Geometric and illumination invariant object representation: application to to content-based image retrieval

This work addresses several issues in the field of computer vision. In particular, attention is focussed on the problem of the representation of an object from its appearance in an image. Advances are proposed for the representation of planar shapes, which are thus suitable for representing planar and faceted objects. The developed representation is employed for content-based retrieval from an image database. The proposed projectively invariant description for groups of planar disjoint contours is obtained as a simultaneous polar reparametrization of multiple curves. Its origin is an invariant point and, for each ray orientation, the cross-ratio of the intersections with the closest curves gives the radius. The sequence of cross-ratio values for all orientations forms a signature. With respect to other methods, this representation is less reliant on individual curve properties, both for the construction of the reference features and for the calculation of the signature. At the same time, this representation integrates local information from multiple curves and thus guarantees robustness to curve discontinuities and partial occlusions. Chromatic information is introduced into the representation and offers two advantages. First, the representation provides a more complete description of the shape and thus becomes more discriminative. Secondly, the chromatic description is illumination invariant under a diagonal chromaticity model and one more acquisition variable is therefore removed. The proposed representation was originally developed for planar shapes, but an extension has been proposed and validated for trihedral corners. A complete system architecture has been implemented, composed of the following stages: feature extraction, reference frame construction, signature evaluation and indexing. The feature extraction stage provides a set of image contours approximated by splines. Joint invariant properties of curves are used to define the reference frame. Invariant signatures are computed from a combination of local properties of multiple curves. These signatures are used as a multidimensional index into a database of signatures and a subset of plausible object views is thus obtained. The invariant signature method has been used for object representation in the context of content-based retrieval from image databases. In particular, we focus on images which portray man-made objects with planar facets or trihedral corners that contain trademarks. lmages were taken from different viewpoints under various illumination conditions. Experimental evaluation has shown that the method is stable to those realistic variations and its performance in this framework is satisfactory. In conclusion, we believe that this approach is an important extension of shape representation methods to a much broader class of objects

Planar Shape Databases With Affine Invariant Search

this paper we show how images in a database can be provided with additional information allowing viewpoint invariant shape query. Viewpoint invariance allows to compensate for affine or projective distortions, and is achieved by the usage of invariant reference frames. Those frames serve as a canonical coordinate system, common for all shapes in the database; in this system their similarity can be estimated and neighbourhood relationships can be established for subsequent search. The contributions of this work are twofold: first, the construction of such reference frames is done by combining different types of local invariant properties of the curve. Second, in the context of search operations, an important speed-up is introduced by means of momentbased indexing. Both strategies are tested on a database of trademarks. The database contains images of supermarket box packages with trademarks placed on their flat sides. Section 2 briefly describes the method for computing viewpoint-independent shape similarity. Section 3 presents the search mechanism, including indexing speed-up routine, and an evaluation of the results

Recognition of planar objects over complex backgrounds using line invariants and relevance measures

This paper addresses the robust recognition of planar polygonal objects situated in 3D space over highly textured backgrounds, where each object is modeled by a set of "five-lines" projective invariants. The main contributions of this work are the following: the establishment of the discriminative ability of an indexing space based on five-lines invariants, the presentation of a robust mechanism for extracting relevant line segments on which invariants are computed, the use of these invariants for geometric hashing amongst possible objects from the model base, and the verification of hypotheses through a purposive search for missing line segments. Finally, experiments verify that the indexing complexity remains linear when the size of the model base increases linearly. Experiments are presented using a model base of 10 shapes, with about 10 views for each shape acquired from various points of view

Projective and illumination invariant representation of disjoint shapes

We describe a new projectively invariant representation of disjoint contour groups which is suitable for shape-based retrieval from an image database. It consists of simul-taneous polar reparametrization of multiple curves where an invariant point is used as the origin. For each ray orientation, a cross-ratio of its intersections with other curves is taken as a value associated to the radius. With respect to other methods this representa-tion is less reliant on single curve properties, both for the construction of the projective basis and for calculating the signature. It is therefore more robust to contour gaps and image noise and is better suited to describing complex planar shapes defined by multiple disjoint curves. Moreover, we show that illumination invariance fits well within the pro-posed framework and can easily be introduced in the representation in order to make it more appropriate for shape-based retrieval. Experiments are reported on a database of real trademarks

Projective and illumination invariant representation of disjoint shapes

We describe a new projectively invariant representation of disjoint contour groups which is suitable for shape-based retrieval from an image database. It consists of simultaneous polar reparametrization of multiple curves where an invariant point is used as the origin. For each ray orientation, a cross-ratio of its intersections with other curves is taken as a value associated to the radius. With respect to other methods this representation is less reliant on single curve properties, both for the construction of the projective basis and for calculating the signature. It is therefore more robust to contour gaps and image noise and is better suited to describing complex planar shapes defined by multiple disjoint curves. The proposed representation has been originally developed for planar shapes, but an extension is proposed and validated for 3D faceted objects. Moreover, we show that illumination invariance fits well within the proposed framework and can easily be introduced in the representation in order to make it more appropriate for shape-based retrieval. Experiments are reported on a database of real trademarks