NdNiMg5, a new magnesium-rich phase with an unusual structural type.

The new intermetallic NdNiMg5 was discovered during the study of the Mg-rich part of the Mg-Nd-Ni system. It was synthetized by melting of the constituent elements in a sealed tantalum tube with subsequent annealing. Its structure was determined by X-ray diffraction on a single crystal.

Extraosseous bone formation obtained by association of mesenchymal stem cells with a periosteal flap in the rat.

Background: Local bone cell therapy consists in grafting a large number of osteocompetent cells in the bone defect. Mesenchymal stem cells (MSC) have been demonstrated as an attractive cell source for tissue-engineering applications because of their ability to be easily isolated and expanded from adult bone marrow and their versatility for pluripotent differentiation into mesenchymal tissues.

Methods: The purpose of our work was to evaluate in vitro the osteogenic potential (proliferation and differentiation) of rat MSC cultured in monolayer conditions and encapsulated in alginate beads and in vivo the osteogenic potential of encapsulated MSC implanted at an extraosseous site associated with a periosteal flap to obtain the equivalent of a vascularized bone autograft.

Enhanced tumor regression and tissue repair when zoledronic acid is combined with ifosfamide in rat osteosarcoma.

The efficacy of zoledronic acid (ZOL), with or without the anticancer drug ifosfamide (IFO), was tested on primary bone tumor growth using a rat-transplantable model of osteosarcoma. The effects on bone remodeling and tumor growth were analyzed by radiography, micro-computed tomography (micro-CT), and histological staining. The in vitro effects of ZOL were studied by proliferation, apoptosis, and cell cycle analyses on the osteosarcoma cells OSRGA compared to rat primary osteoblasts.

Downregulation of osteoblast markers and induction of the glial fibrillary acidic protein by oncostatin M in osteosarcoma cells require PKCdelta and STAT3.

Unlabelled: The effects of OSM on proliferation and differentiation of osteosarcoma and nontransformed osteoblasts were analyzed. OSM downregulates osteoblast markers but induces the glial fibrillary acidic protein by the combined activation of PKCdelta and STAT3, offering new lines of therapeutic investigations.

Introduction: Oncostatin M (OSM) is a multifunctional cytokine of the interleukin-6 family implicated in embryonic development, differentiation, inflammation, and regeneration of various tissues, mainly the liver, bone, and the central nervous and hematopoietic systems.

Cellular activity and signaling induced by osteoprotegerin in osteoclasts: involvement of receptor activator of nuclear factor kappaB ligand and MAPK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), an inducer of osteoclastogenesis via its receptor RANK. We recently demonstrated that OPG also exerts a direct effect in osteoclasts by regulating protease expression. Herein, we showed that OPG-induced pro-matrix metalloproteinase-9 activity was abolished by ras/MAPK inhibitors in purified osteoclasts.

Relevance of an in vitro osteoclastogenesis system to study receptor activator of NF-kB ligand and osteoprotegerin biological activities.

Receptor activator of NF-kB Ligand (RANKL) is an essential requirement for osteoclastogenesis and its activity is neutralized by binding to the soluble decoy receptor osteoprotegerin (OPG). The purpose of this work was to study the effects of RANKL and OPG during osteoclastogenesis using the murine monocytic cell line RAW 264.7 that can differentiate into osteoclasts in vitro.

Receptor activator of nuclear factor kappaB ligand (RANKL)/osteoprotegerin (OPG) ratio is increased in severe osteolysis.

Pathological osteolyses are considered a consequence of a disturbance in the mechanisms that govern the bone remodeling, mainly the communication between osteoclasts and osteoblasts. Osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) are newly discovered molecules that play a key role in these communications. RANKL is essential for osteoclast differentiation via its receptor RANK located on the osteoclast membrane.

Regulation of osteoclast protease expression by RANKL.

Receptor activator of NF-kappaB ligand (RANKL) is essential for osteoclast (OC) differentiation/activation and functions through its receptor RANK at the surface of the osteoclastic cells. This study investigated for the first time the direct effects of hRANKL on protease/protease inhibitor expressions and protease activities in purified rabbit osteoclast cultures, using semi-quantitative RT-PCR, gelatin zymography, and enzymatic assays. RANKL was shown to exert in vitro pro-resorptive effects by increasing osteoclast marker expressions (Tartrate resistant acid phosphatase (TRAP) and cathepsin K), MMP-9 expression, and pro-MMP-9 activity and by diminishing TIMP-1 expression, leading to an up-regulation of the MMP-9/TIMP-1 ratio.

Osteoprotegerin differentially regulates protease expression in osteoclast cultures.

Cysteine proteases and matrix metalloproteinases (MMPs) are important factors in the degradation of organic matrix components of bone. Osteoprotegerin (OPG) is an osteoblast-secreted decoy receptor that inhibits osteoclast differentiation and activation. This study investigated the direct effects of human OPG on cathepsin K, MMP-9, MMP-2, and tissue inhibitors of metalloproteinases (TIMP1 and TIMP2) expressed by purified rabbit osteoclasts.

Osteogenic potential in vitro of human bone marrow cells cultured on macroporous biphasic calcium phosphate ceramic.

Calcium phosphate ceramics are synthetic bone substitutes that promote bone formation by osteoconduction. However, they have shown an osteogenic potential in vivo in animal models when associated with bone marrow cells. In order to develop an osteogenic human "hybrid material," we studied the in vitro osteogenic potential of human bone marrow cells cultured on macroporous biphasic calcium phosphate (BCP) pellets in the presence of dexamethasone with or without 1alpha,25 dihydroxyvitamin D3.

Presence of leukaemia inhibitory factor (LIF) and LIF-receptor chain (gp190) in osteoclast-like cells cultured from human giant cell tumour of bone. Ultrastructural distribution.

The behaviour of multinucleated giant cells (MNC) obtained from a giant cell tumour of the tibia and cultured on glass coverslips or on devitalized dentin slices was investigated using light and electron microscopy. Cells were studied in the presence or absence of LIF a cytokine known to be involved in bone turnover and to act as a growth factor in some solid tumours. The direct effect of LIF on MNC was examined by a post-embedding colloidal gold immunocytochemistry process using human anti-LIF and anti-LIF-receptor (chain gp190) antibodies.

Expression of leukemia inhibitory factor by cartilage-forming tumors of bone: an immunohistochemical study.

Recent studies have implicated leukemia inhibitory factor in connective-tissue metabolism involving the remodeling of bone and the destruction of cartilage tissue. This cytokine, which has also been implicated in the proliferation of solid tumor, is expressed by osteotropic tumor cell lines. The present study investigated the presence of leukemia inhibitory factor in cartilage tissue harvested from cartilage-forming bone tumors.

Growth hormone-loaded macroporous calcium phosphate ceramic: in vitro biopharmaceutical characterization and preliminary in vivo study.

Calcium phosphate ceramics recently have been used for administering therapeutic agents in bone. The present work investigated the efficacy of macroporous biphasic calcium phosphate (MBCP) implants as a matrix for local delivery of human growth hormone (hGH). An initial study showed that the release of 5 microg of hGH loaded onto MBCP cylinders was rapid during the first 48 h and sustained for a total of 11 days.

Human growth hormone locally released in bone sites by calcium-phosphate biomaterial stimulates ceramic bone substitution without systemic effects: a rabbit study.

Calcium-phosphate bone replacement biomaterial has been used as a drug carrier for therapeutic agents. This study investigated the efficacy of local administration of human growth hormone (hGH) by macroporous biphasic calcium phosphate (MBCP) implants in improving the bone substitution qualities of ceramics. hGH release from MBCP implants loaded with 1 microg of hGH was rapid during the first 48 h and then sustained for a total of 9 days.