Objective:To establish a multidrug resistant human salivary adenoid cystic carcinoma cell line. Methods:Salivary adenoid cystic cells of the cell line SACC were exposed to 1 ?g/ml of DDP for 48 h at the interval of one month. 6 months later, the cell line was established and named SACC/DDP. MTT method was used to study the drug resistance of SACC and SACC/DDP cells against 4 chemotherapeutic agents(MTX, PYM, VCR, MMC). Flow cytometry was adopted to study the cell cycle distribution of the cells after treatment with 4 agents at different concentrations for 72 h. Results:The drug resistance of SACC/DDP cells against VCR,MTX,PYM and MMC was 2.9,2.4,1.1 and 1.8 times of that of SACC cells. The ratio of G0 cell number to G1 cell number in SACC/DDP cell line was smaller than that in SACC cell line after treatment with the 4 agents at different concentrations respectively.Conclusion:The multidrug resistant human salivary adenoid cystic carcinoma cell line can be estabished by exposing parent cell line SACC periodically to DDP.

Objective To evaluate the effects of recombinant human bone morphogenetic-2-polylactide sustained release nanospheres (rhBMP-2-PLA-Ns) on cultured rabbit osteoblasts in vitro. Methods Rabbit osteoblasts were cultured in vitro, and rhBMP-2-PLA-Ns was added into the medium of the third generation of rabbit osteoblasts. The expression of the proliferating cell nuclear antigen (PCNA) was examined by immunofluoreacence staining, and the formation of tuberculums observed with alizarin red staining. Western blot was used to detect the effects of rhBMP-2-PLA-Ns on the expression of vascular endothelial growth factor (VEGF), which was compared with that in rhBMP-2 group and blank group. Results There was no significant difference in the number of osteoblasts with positive PCNA expression among three groups five days later. Ten days later, the number of osteoblasts with positive PCNA expression in rhBMP-2-PLA-Ns group was significantly higher than that in rhBMP-2 group and blank group, which indicated that rhBMP-2-PLA-Ns could enhance the expression of PCNA. Compared with rhBMP-2 group and blank group, rhBMP-2-PLA-Ns could significantly enhance the formation of tuberculums, with statistical difference (P<0.05). The expression of VEGF was detected in all three groups, and the level of the VEGF expression in rhBMP-2-PLA-Ns group was significantly higher than that in the other 2 groups (P<0.05). Conclusion The biological activity of rhBMP-2-PLA-Ns is superior than that of rhBMP2, and rhBMP-2-PLA-Ns can promote the proliferation, mineralization of osteoblasts and the secretion of VEGF, which has a better prospect in facilitating traumatic bone healing.

Objective To establish a three-dimensional (3D) finite element model of a swine mandible, simulate the dynamic procedure of bullet damaging the swine mandible and explore a finite ele-ment analysis method on maxiilofacial gunshot wound. Methods The digital imaging and communica-tions in medicine (DICOM) data obtained from CT scanning of a swine mandible were remerged into a 3D finite element model of the original specimen through Mimics and ANSA software, then a simulation of 3D finite element model penetrated by a 7.62 mm bullet was carried out through LS-DYNA software. The simulation data were compared with those from animal experiment in laboratory to test the feasibility of 3D finite element model and the simulation method. Results A 3D finite element model of a swine mandi-ble was established, with highly identical geometric size with the specimen. In the meantime, the dynam-ic process of a 7.62 mm bullet damage to the model was successfully simulated. Data from the simulation and those from animal experiment showed a high level of consistency. Conclusion 3D finite element method is prosperous in application in basic research on maxillofacial gunshot wound.

Objective To investigate the changes of the expression of osteoprotegerin (OPG) and receptor activator nuclear factor kappa B ligand (RANKL) during the healing of mandibular fracture after the transection of the inferior alveolar nerve (IAN) in rabbits. Methods Forty rabbits were randomly divided into 2 groups and each group consisted of 20 animals. The rabbits of the first group underwent mandibular fracture and transection of IAN and those of the second group underwent mandibular fracture only. The rabbits were killed at 7, 14, 21, 28 day after fracture. The callus tissue of the rabbits was collected and paraffin sections of the callus tissue were prepared. The callus sections were subjected to HE staining. The effects of calcitonin gene-related peptide (CGRP) on the expression of OPG and RANKL were observed with immunohistochemical staining. Results There were only a few CGRP immunoreactive nerve fibers at day 7 after IAN section. Low level of OPG expression was found throughout the repair process but RANKL was intensively expressed in the rabbits of the first group. Conclusion CGRP can up-regulate the expression ratio of OPG/RANKL and promote the healing process of fracture. The loss of CGRP is unfavorable to bony healing.