system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Angiogenesis Inducing Agents, Animals, Bony Callus, Carrier Proteins, Cytokines, Female, Fracture Healing, Growth Substances, Image Processing, Computer-Assisted, Immunohistochemistry, Rats, Rats, Sprague-Dawley.
user
Is the angiogenic peptide pleiotrophin ( PTN/HB-GAM ) expressed in fracture healing : an immunohistochemical study in rats? Context: Formation of new blood vessels is essential for the process of fracture healing. We investigated the expression of the angiogenic factor pleiotrophin/HB-GAM in a closed fracture model in rats by immunohistochemical methods. Histologically, 5 days after fracture the callus was predominantly composed of fibrous tissue. On day 10 a prominent chondral callus connected both ends of the fractured tibia. There was a continuous transition from the chondral callus to the newly formed bone adjacent to the corticalis of the tibia. On day 15 the amount of woven bone had increased, and in 3 of 5 animals the proximal and distal tibiae were connected by a bridge of woven bone. Pleiotrophin could be immunostained in fibroblasts and endothelial cells of the fibrous tissue between the fractured tibia ends. The chondral callus remained largely pleiotrophin-negative. Only single chondrocytes adjacent to the newly formed bone were pleiotrophin-positive. On days 10 and 15 strong immunoreactivity for pleiotrophin in the well vascularized, newly formed, woven bone was detectable. Osteoblasts, endothelial cells and fibroblasts were strongly pleiotrophin-positive.
assistant
These results show the presence of the angiogenic peptide pleiotrophin during fracture healing. Final Decision: yes