Objective: To study the precise stress distribution in the apical foramen area of endodontic endosseous implant. Methods:After analysis of the two-dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains for calculation. Results:Under 45? axial right oblique loading, the stress concentration occurred in both infinite domains of the apical foramen. The tension stress concentrated in the infinite domain near the load side,but the other side was compress concentrated. Two stress concentration points were just at the central points, which were intersections between implant and dentin. In the implant and dentin section, the stress reduced in all directions from two stress concentration points, but in the ligament section, the result was contrary. Conclusion:It is helpful to keep the root stable when the fulcrum of the root changed to lower part after restoration. In the implant area,the diameter of implant at the apical foramen of root shouldn't be reduced for the protection of root in clinical work;It is very important to preserve the tissue of periodental ligament for endodontic endosseous implants.

砄bjective: To establish two dimensional infinite model for endodontic endosseous implants in order to set up infinite element method and study the stress distribution of the apical foramen area of endodontic endosseous implant. Methods: Based on the analysis of two dimensional endodontic endosseous implants model with finite element method, left and right areas beside the apical foramen were selected as infinite domains including implant dentin and ligament sections. D N interactive method was used to connect the finite and infinite domains. Results: After ten times interaction between finite and infinite domains with D N interactive method, the outcome approached to a stable numerical value close to the displacement of both domains. Conclusion: The infinite model of two dimensional endodontic endosseous implants established by D N interactive method is efficient and accurate.

Objective To identify the effect of decreasing the rejection using the biological semipermeable membrane combined with the privileged site xenotransplantation. Methods The rat ICCs encapsulated by biological semipermeable membrane were xenotransplanted into dog's brain. The pathological changes of implants and surrounding cerebral tissues were observed under light and electric microscopy. The ?-cells of implants were identified by immunohistochemistry. Results After 2 months of transplantation, The ?-cells were observed and the lymphocytes were dispersed in the grafts.The brain tissues near the grafts showed slight edema and glial hyperplasia. Conclusion The method using the biological semipermeable membrane in combination with the privileged site xenotransplantation have a beneficial effect on the inhibition of the rejection of heterogeneous ICCs implant.

Objective:To study the residual stress distribution through the thickness of bilayered dental ceramic subjected to thermal stress, in order to improve the restoration. Methods: The finite element model of bilayered dental ceramic was set up based on International Organization for Standardization(ISO) 96936:1999. The residual stresses were calculated in viscoelastic and elastic phases during cooling of dental ceramic to analyze the residual stress distribution. Results: The deformation of core was greater than the veneer ceramics during the cooling period of dental ceramic. The residual stress increased with the decreasing of the temperature approaching the interface of core and veneer ceramics. But it decreased with the increasing of the thickness of veneer ceramics.Conclusion: Thermal compatibility of core and veneer ceramics is very important to the residual stress distribution in the bilayered dental ceramic, which may benefit to All-ceramic restorations. The viscoelastic behavior of ceramic should be taken into account in the thermal compatibility.

Objective To design and manufacture an external fixator for close reduction of fibu la and tibial fractures.Methods The all-ring reduction and fixation system made of duroplasts comprises three main parts:two reduction rings with gears and worms,two modulation frames to correct lateral or anteroposterior re-placement,and four connecting rods.By cranking the handle,the gears wi ll be driven,which may in turn shift t he modulation frame,then the needle co nnecting the bone with the frame can s hift the fracture ends in three dimen sions and six freedom degrees.After reduction,the fracture is fixed by the cro ssed needles linked to several groups of half-ring fixation arms,which can b e shifted and locked onto the linking rod properly.Results The apparatus was used in 32patients.All cases got anatomic reduction,and the curativ e ratio was 100%.Conclusion The external fixator for close reductio n of tibial and fibula fractures has g ood reduction and fixation effect,a nd the design provides a very good clinical therap eutic method for close reduction of t ibial and fibula fractures.[

Objective To study the clinical characteristics, treatment methods and prognosis of primary gastrointestinal diffuse large B-cell lymphoma (PGI-DLBCL). Methods The clinical data of 40 patients with PGI- DLBCL were retrospectively analyzed. All the cases had received surgery treatment. Results In 40 patients with PGI-DLBCL, the major clinical presentation included abdominal pain in 15 cases (37.5%), abdominal mass in 6 cases (15.0%), abdominal discomfort in 5 cases (12.5%), abdominal distension in 5 cases (12.5%), and hematemesis in 5 cases (12.5%). Fifteen cases were misdiagnosed as gastric cancer, 5 cases as colon cancer, and 4 cases as digestive tract ulcer. The misdiagnosis rate was 60.0% (24/40). The survival rates of 1- , 2- and 3- year were 62.3%, 57.5% and 52.6%. The univariate analyses result showed that the clinical stage, international prognosis index (IPI) and treatment method were associated with survival rate (P<0.01), but the gender, age and disease distribution were not associated with survival rate (P > 0.05). The 3-year survival rate of clinical stage Ⅰ - Ⅱ was significantly higher than clinical stageⅢ-Ⅳ(68.0%vs. 13.3%), the 3-year survival rate of IPI 0-2 scores was significantly higher than 3 - 5 scores (66.7% vs. 7.6%), and the 3- year survival rate of surgery combined with postoperative chemotherapy was significantly higher than simple surgery (75.0%vs. 20.0%), there were statistical differences (P<0.01). Conclusions The patients with PGI- DLBCL have no obvious clinical manifestions and a higher misdiagnosed rate. Modified IPI, clinical stage and surgery combined with postoperative chemotherapy are the influencing factors of prognosis.

Objective To evaluate and analyze the diagnostic accuracy of 256-slice computed topographic angiog-raphy (CTA) and coronary angiography (CAG) in patients with coronary artery disease (CAD). Methods One hundred and one patients (suspected CAD and confirmed CAD with re-examination) underwent the 256-slice CTA and CAG were includ-ed in this study. The coronary artery imaging data of 101 patients were retrospectively collected and analyzed. Calculations for accuracy were conducted on a segmental basis. A total of 1 313 comparable segments were evaluated. The accuracy of 256-slice CTA was evaluated in the diagnosis of moderate and severe stenosis of coronary artery(stenosis in segments of cor-onary artery≥50%). The values for diagnostic accuracy of 256-slice CTA were analyzed, including mild stenosis: ＜50%, moderate stenosis:50%~75%, severe stenosis:76%~100%and complete occlusion. Results The sensitivity of 256-slice CTA for diagnostic accuracy to coronary heart disease was 94.87%, and the specificity was 52.17%. The positive predictive value was 87.06%and the negative predictive value was 75.00%. The accuracy rates of 256-slice CTA for evaluating the cor-onary artery stenosis were:mild stenosis (44.23%), moderate stenosis (44.23%), severe stenosis (40.00%) and total occlusion of coronary artery (51.77%), respectively. Conclusion The diagnostic value of 256-slice CTA for the degree of coronary ar-tery stenosis is insufficient, which can be used as a potential alternative screening examination to detect coronary artery ste-nosis in suspected patients and a method of re-examination in low risk patients with CAD.

Sixty patients with esophageal carcinoma undergoing thoracoscopic-laparoscopic resection were randomly divided into two groups with 30 cases in each group:endobronchial blocker was used during operation in group E and double-lumen tube( DLT) was used in group D.The results showed that compare to group D,intubation time was shorter and the incidence of postoperative hoarseness and sore throat was lower in group E [(27.4 ±8.6) vs.(37.2 ±10.3)s, 1 and 9 cases,5 and 14 cases, all P<0.05 ]; while the incidence of blockage shifting was higher in group E than group D (4 cases and 0, P<0.05).There were no significant differences in positioning time and effects of one lung ventilation between two groups[(115.6 ± 25.2) vs.(112.2 ±27.2) s, P>0.05].The study indicates that application of endobronchial blocker can reduce the incidence of postoperative hoarseness and sore throat and shorten the intubation time;especially, it is easy to operate and there is no need to replace the tube after surgery.

Objective To evaluate the effects of ischemic preconditioning(IP) on liver function,complications and hospital stays after hepatectomy under hepatic vascular exclusion by a meta-analysis.Methods Randomized controlled trials(RCTs) were identified from PUBMED,EMBASE,the Cochrane Library,VIP,CNKI and Wanfang Data according to the inclusion and exclusion criteria.Literature screening,data extraction and quality assessment were made and the meta-analysis was processed by RevMan 4.2.2.Results Eight RCTs involving a total of 511 patients were included.The methodological quality was evaluated and all the trials were in graded B.The meta-analysis revealed that the postoperative ALT peak level(weighted mean difference=-176.37;95%CI:-320.67~-30.06;P=0.02)and postoperative complications incidence(odd ratio=0.64;95%CI: 0.41~0.98;P=0.04)were lower in IP group compared with control group,but there were no significant differences in blood loss,operating time,hepatic vascular exclusion time,postoperative AST and total bilirubin peak level,and hospital stays in both groups.Conclusions IP reduces the postoperative ALT peak level and complications incidence after hepatectomy under hepatic vascular exclusion,but there is no sufficient evidence to support that the IP can protect the liver from ischemia/reperfusion injury.

Objective To explore the relationship between nuclear factor-?B(NF-?B) and(P-glycoprotein)((P-gp)) on K562/A02 cells.Methods NF-?B and P-gp of K562/A02 cells cultured with PDTC in different concentrations and time were detected by immunohisochemisty,and the relationship between them was analyzed.Results In K562/A02 cells,the expression of NF-?B and P-gp were positively correlated,and were concentration-dependent and the time dependent.Conclusion The mechanism of NF-?B regulating anti-apoptosis of K562/A02 cells is related with MDR1.