Latexin expression correlated with mineralization of articular cartilage during progression of post-traumatic osteoarthritis in a rat model.

As latexin has been linked with chondrocyte hypertrophic differentiation it is possible that this protein may also be involved in the mineralization of cartilage in OA. Therefore, we correlated latexin expression with the mineralization marker, alkaline phosphatase and determined the mineral deposition in the articular cartilage by analyzing the Ca/P ratio and the collagen fibrils pattern, during the progression of post-traumatic OA in a rat model. OA was induced by medial meniscectomy and post-surgery exercise for 5, 10, 20 and 45 days.

Genetic abrogation of the fibronectin-α5β1 integrin interaction in articular cartilage aggravates osteoarthritis in mice.

The balance between synthesis and degradation of the cartilage extracellular matrix is severely altered in osteoarthritis, where degradation predominates. One reason for this imbalance is believed to be due to the ligation of the α5β1 integrin, the classic fibronectin (FN) receptor, with soluble FN fragments instead of insoluble FN fibrils, which induces matrix metalloproteinase (MMP) expression. Our objective was to determine whether the lack of α5β1-FN binding influences cartilage morphogenesis in vivo and whether non-ligated α5β1 protects or aggravates the course of osteoarthritis in mice.

Menisectomized miniature Vietnamese pigs develop articular cartilage pathology resembling osteoarthritis.

Animal models have been used to understand the basic biology of osteoarthritis (OA) and have helped to identify new candidate biomarkers for the early diagnosis and treatment of this condition. Small animals cannot sufficiently mimic human diseases; therefore, large animal models are needed. Pigs have been used as models for human diseases because they are similar to humans in terms of their anatomy, physiology and genome.

Regulation of α5 and αV Integrin Expression by GDF-5 and BMP-7 in Chondrocyte Differentiation and Osteoarthritis.

The Integrin β1 family is the major receptors of the Extracellular matrix (ECM), and the synthesis and degradation balance of ECM is seriously disrupted during Osteoarthritis (OA). In this scenario, integrins modify their pattern expression and regulate chondrocyte differentiation in the articular cartilage. Members of the Transforming growth factor beta (Tgf-β) Superfamily, such as Growth differentiation factor 5 (Gdf-5) and Bone morphogenetic protein 7 (Bmp-7), play a key role in joint formation and could regulate the integrin expression during chondrocyte differentiation and osteoarthritis progression in an experimental OA rat model.

Exercise modulates the expression of IL-1β and IL-10 in the articular cartilage of normal and osteoarthritis-induced rats.

After a joint lesion, high-impact exercise is a risk factor for the development of osteoarthritis (OA). The degradation of articular cartilage in OA has been associated with the activation of inflammatory cytokine signaling pathways. However, differences in cytokine expression in healthy and injured cartilage after exercise have not yet been analyzed.

Proteomic analysis of rat cartilage: the identification of differentially expressed proteins in the early stages of osteoarthritis.

Background: Osteoarthritis (OA) is a chronic degenerative disease of the articular cartilage, and its diagnosis is based on symptoms and radiological signs that are only present in the late stages of the disease. Due to the limitations in diagnosing OA before the onset of symptoms, such as pain, little is known about the molecular mechanisms involved in the pathogenesis of OA. Experimental OA models are often used to study the kinetics of the progression of this disease.

Changes in the integrins expression are related with the osteoarthritis severity in an experimental animal model in rats.

We identify changes in the expression and localization of α5, α4, and α2 integrins during osteoarthritis (OA) pathogenesis in a rat experimental model. The changes were concomitant with variations in the extracellular matrix (ECM) content and the increase of metalloproteinases (MMPs) activity during OA pathogenesis, which were analyzed by immunofluorescence and Western blot assays. Our results showed an increased expression of α5 and α2 integrins at OA late stages, which was co-related with changes in the ECM content, as a consequence of the MMPs activity.

Identification of latexin by a proteomic analysis in rat normal articular cartilage.

Background: Osteoarthritis (OA) is characterized by degeneration of articular cartilage. Animal models of OA induced are a widely used tool in the study of the pathogenesis of disease. Several proteomic techniques for selective extraction of proteins have provided protein profiles of chondrocytes and secretory patterns in normal and osteoarthritic cartilage, including the discovery of new and promising biomarkers.

Expression of MIG-6, WNT-9A, and WNT-7B during osteoarthritis.

Although the molecular mechanisms for initiation of cartilage destruction in osteoarthritis (OA) are unknown, it has been demonstrated that disruption of mitogen-inducible gene 6 (Mig-6) in mice leads to the onset of a degenerative joint disease like OA. On this basis, we correlated gene expression of Mig-6 with Wnt-9a and Wnt-7b genes; we showed downregulation of Mig-6, Wnt-7b, and Wnt-9a during OA, while Wnt-7b was expressed also in osteoblast-like cells. Here we suggest that Aggrecan degradation occurs before the downregulation of Mig-6.

Chondrocytes interconnecting tracks and cytoplasmic projections observed within the superficial zone of normal human articular cartilage--a transmission electron microscopy, atomic force microscopy, and two-photon excitation microscopy studies.

The morphology of the normal human and rat articular cartilage was assessed using transmission electron microscopy (TEM), atomic force microscopy (AFM), and two-photon excitation (2PE) microscopy. Spurr-embedded sections from fixed human cartilage were simultaneously evaluated using TEM and AFM. The presences of tracks among the chondrocytes from the superficial zone of the cartilage were observed.

Identification of exocytotic membrane proteins, syntaxin-1 and SNAP-25, in Entamoeba histolytica from hamster liver.

Entamoeba histolytica is a protozoan parasite causing dysentery and in some cases liver abscesses. These effects have been attributed to cytolytic substances released by exocytosis. In this study, the presence of the proteins syntaxin-1 and SNAP-25, which are assumed to be involved in exocytosis, were examined by immunohistochemistry, immunoelectron microscopy and western blot analysis.

The bactericidal effect of silver nanoparticles.

Nanotechnology is expected to open new avenues to fight and prevent disease using atomic scale tailoring of materials. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios and crystallographic surface structure. The study of bactericidal nanomaterials is particularly timely considering the recent increase of new resistant strains of bacteria to the most potent antibiotics.

Ontogeny of rat chondrocyte proliferation: studies in embryo, adult and osteoarthritic (OA) cartilage.

The aim of this work was to study the ontogeny of chondrocyte cell division using embryo, adult and osteoarthritic (OA) cartilage. We searched for mitosis phases and performed a comparative evaluation of mitotic index, basic fibroblast growth factor b (FGFb), transforming growth factor beta1 (TGF-beta1) receptors, cyclin dependent kinase (CDK1) and Cyclin-B expression in fetal, neonate, 3, 5, 8 weeks old rats and experimental OA. Our results showed that mitosis phases were observed in all normal cartilage studied, although, we found a decrease in mitotic index in relation to tissue development.

A new role for chondrocytes as non-professional phagocytes. An in vitro study.

Chondrocytes are capable of engulfing latex particles, cell detritus, and necrotic and apoptotic remains in vitro. It is conceivable that chondrocytes might be involved in the clearance by phagocytosis of different materials within the cartilage. In fact, so far there is no evidence for the presence of "professional phagocytes" (macrophages and neutrophils) in this tissue.

Modifications of Golgi complex in chondrocytes from osteoarthrotic (OA) rat cartilage.

The status of the Golgi complex in normal vs osteoarthrotic (OA) cartilage has not yet been studied. A monoclonal antibody, MAb 58-K-9, allowed scoring of Golgi labeling intensity. In addition, ultrastructural assessment enabled us to focus on the distribution and relation between the endoplasmic reticulum (ER) and Golgi membranes.