1. Wear particle mediated osteolysis - We have clearly established that osteoprogenitor cells represent one of the target cell types dramatically affected by the presence of wear debris particles derived from metallic orthopaedic implant materials. Particle treated adult stem cells slow down in their proliferation, are induced to undergo apoptosis, and are inhibited in osteogenic differentiation. Our recent study focuses on the possible role of cytokines and anoxia in mediated these effects. 2. Molecular detection of orthopaedic infections - We have developed polymerase chain reaction (PCR)-based technologies for the detection of bacterial infection in orthopaedically relevant tissues, specifically septic arthritis and periprosthetic infection. By targeting RNA, both mRNA and rRNA, we are able to use quantitative reverse transcription-PCR (qRT-PCR) to detect as well as assess the viable bacterial load. A clinical series utilizing synovial fluid is being analyzed to test potential clinical application of the technology. 3. Supraphysiological impact mediated cartilage degeneration model - We have developed a reproducible, spring-loaded impactor based rabbit model to study impact-induced articular degeneration. We are focusing on the analysis of early cellular responses that lead to subsequent osteoarthritis-likd articular cartilage degeneration. 4. Animal model of distraction osteogenesis - A unique and effective procedure to induce postnatal bone growth, the mechanism of distraction osteogenesis is not well understood. We have developed and completed a study of a mouse model to analyze the gene expression events accomanying distraction osteogenesis. In addition, we are developing an in vitro mechanical activation model using culture cells in 2-D and 3-D conditions to simulate distraction osteogenesis. 5. Glucosamine as a chondroprotecive agent - The nutriceutical, glucosamine, has been widely used for joint pain and other related disease states. However, the mechanism of action remains elusive. We have investigated the efficacy of glucosamine in blocking the chondrodestructive activity of interleukin-1 beta. Our results showed that early or concomitant treatment with physiological concentrations of glucosamine effectively suppress the deleterious effects of the pro-inflammatory cytokine.