BACKGROUND:Bone defects are the leading cause of nonunion after firearm injury. Firearm injury is relatively special. Autograft and alograft al have big drawbacks, which cannot meet the requirements of basic-level hospitals. Using tissue-engineered bone with good blood vessels and osteogenic capability in repair of firearm bone defect wil be an ideal and feasible restoration method. OBJECTIVE: To explore the application of human vascular endothelial growth factor 121 gene-modified materials in the repair of firearm-induced radial injury in rabbits. METHODS: A total of 128 rabbits were randomly divided into surgical injury group and firearm injury group (n=64 per group). In the firearm injury group, 0.25 g steel bal was launched using 56-style musket to establish a firearm radial injury model; in the surgical injury group, surgical methods were used to produce a 1.2 cm radial injury model. Human vascular endothelial growth factor 121 gene-modified materials were used. The related histocytes from rabbits were harvested to obtain bone marrow stromal cels for culture. A porous scaffold material was prepared. The obtained materials were respectively implanted into radial defect sites in the surgical injury and firearm injury groups. The application of human vascular endothelial growth factor 121 gene-modified materials in rabbit radial defect repair was analyzed. RESULTS AND CONCLUSION: Compared with the surgical injury group, at 8, 12 and 16 weeks after repair, the gray level ratio of bone defect site and the anti-compression mechanical ratio at the healthy and repairing sides of the radius in the firearm injury group were decreased (P < 0.05), and the new bone area increased (P < 0.05). At 2 and 4 weeks after repair, the local blood flow at the repair area was significantly increased (P < 0.05). These results suggest that compared with the surgical injury group, the curative effect of human vascular endothelial growth factor 121 gene is more ideal in the firearm injury group because of the emergence of local ischemia and hypoxia in the process of radial defect repair. Human vascular endothelial growth factor 121-modified material can repair bone marrow stromal cels. The application of human vascular endothelial growth factor 121 in firearm burns can enhance the synthesis and secretion of angiogenic factors, improve the local blood flow, reduce anti-compression mechanical ratio, and increase the new bone area.

Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine.
Acrylates ; administration & dosage ; chemistry ; Anti-Inflammatory Agents, Non-Steroidal ; administration & dosage ; Chitin ; administration & dosage ; analogs & derivatives ; chemistry ; Delayed-Action Preparations ; Diclofenac ; administration & dosage ; Drug Carriers ; chemical synthesis ; Drug Delivery Systems ; Hydrogel, Polyethylene Glycol Dimethacrylate ; administration & dosage ; chemistry ; Hydrogen-Ion Concentration

AS1. 398 neutral protease was immobilized onto carboxymethyl chitosan with glutaraldehyde as cross-linking agent. The effects of pH, time of cross-linking, amount of cross-linking agent and the ratio of enzyme to carrier on the activity of the immobilized enzyme were demonstrated, and the optimum immobilization condition of AS1. 398 neutral protease was established. Also studied was the characterization of immobilized enzyme,including pH, temperature, Km and the stability of storage.
Bacterial Proteins ; chemistry ; Chitosan ; analogs & derivatives ; pharmacology ; Endopeptidases ; chemistry ; Enzymes, Immobilized ; chemical synthesis ; chemistry ; Glutaral ; pharmacology ; Microspheres