OBJECTIVETo investigate the reversal effect of dihydromyricetin(DMY) on drug resistance of K562/A02 cells to adriamycin and explore its possible mechanism.

METHODSK562 and K562/A02 cells were treated with DMY (5, 10, 20, 40, 60, 80 and 100 mg/L) and ADM (100-0.05 mg/L) for 48 h. The viability of K562 cells and K562/A02 cells was tested and the reversal effect of DMY on drug resistance of K562/A02 cells to adriamycin was analyzed by MTT. The relative concentration of ADM in cells was measured by flow cytometry. Protein expressions of drug resistance related genes including P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1), glutathione transferase π (GSTπ) and BCL-2 were measured by Western Blot.

RESULTSThe proliferation of K562 and K562/A02 cells was significantly decreased by DMY in dose-dependent manner as compared with control group (r1=0.37, r2=0.38). The ICof ADM on K562 and K562/A02 cells were 71.23±6.51 and 72.88±5.49 mg/L respectively. DMY (5, 10 and 20 mg/L) was low cytotoxicity. DMY (5, 10 and 20 mg/L) enhanced the sensitivity of K562/A02 cells to ADM in dose-dependent manner (r1=-0.62, r2=-0.71) and the reversal multiples was from 1.38 to 28.591. The relative concentrations of ADM in K562/A02 of DMY (5, 10 and 20 mg/L) group cells were significantly increased in dose-dependent manner compared with the control group (r=0.34). Compared with the control group, the expressions of drug resistance related protein P-gp, MRP1, GSTπ and BCL-2 were significantly decreased in dose-dependent manner in DMY (5, 10 and 20 mg/L) group (r1=-0.41, r2=-0.37, r3=-0.58, r=-0.46). Compared with the ADM group, the protein expressions of drug resistance related genes P-gp, MRP1, GSTπ and BCL-2 in DMY (5, 10 and 20 mg/L)+ADM group were significantly decreased in dose-dependent manner (r1=-0.55, r2=-0.41, r3 =-0.38, r4=-0.44).

CONCLUSIONDMY enhances the sensitivity of K562/A02 cells to ADM, its mechanism may be related with decrease of P-gp, MRP1, GSTπ and BCL-2 expressions.

Objective To establish a smooth three-dimensional(3D)geometric model of the maxilla based on CT data using four dif-ferent software packages,to mimic the modified Le Fort Ⅰ osteotomy and its fixation scheme,and to perform a finite element analysis of the postoperative occlusion.Methods CT data were preliminarily processed using Mimics software to produce an STL 3D model.The model was then imported into Inspire Studio software to create a smoothed PolyNURBS geometric model.SpaceClaim software was used to model the surgical osteotomy and fixation schemes.Finally,ANSYS Workbench was used to conduct a 3D finite element analysis simu-lating the patient's occlusion after surgery.Results The simulation results showed that the connection relationship of the finite element model was accurately established under the molar occlusion condition.Under a total occlusal force of 6 N,the maximum equivalent stress of the titanium plate was 73 MPa.Conclusion The maxillary modeling and analysis method used in this study can produce a smooth geometric model suitable for finite element simulation.The results of this study can provide reference for various fixation schemes in orthognathic surgery.

Objective To explore the effect of attachment wear on tooth movement in clear Aligner treatment, and to provide references for improving the efficiency of orthodontic treatment. Methods The tooth cone bean computed tomography (CBCT) scanning data were obtained, and the tooth model was established and assembled with the worn and complete attachment, respectively. When the appliance applied 2° distal torsion, 0.25 mm distal displacement, 0.1 mm depression displacement and 0.1 mm elongation displacement to the teeth, the changes of tooth displacement, periodontal ligament stress and root equivalent stress in the worn and complete attachment groups were compared. Results When the clear Aligner was used to apply distal torsion and elongation displacement to the teeth, the maximum tooth displacement decreased significantly, and the worn attachment caused the teeth to move obliquely when the distal translation and elongation displacement occurred. When the tooth was subjected to distal torsion, distal translation, depression and elongation, the maximum principal stress of periodontal ligament and the equivalent stress of tooth root decreased when the worn attachment caused the tooth to be subjected to distal torsion, distal translation, depression and elongation. Conclusions Attachment wear will affect the efficiency of tooth rotation and elongation.When the attachments are obviously worn, they should be replaced in time to ensure normal function of the attachments.