BACKGROUND:The form and structure of antigen-extracted xenogeneic cancel ous bone through series of physical and chemical treatment are similar to human tissue. OBJECTIVE:To detect the biocompatibility of antigen-extracted xenogeneic cancel ous bone matrix prepared by three different ways. METHODS:The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods and hydroxy apatite biological ceramic materials were implanted into the dorsum subcutaneous tissue. Histological observation was done at 4, 8 and 12 weeks after surgery. The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods respectively was used to culture sheep bone marrow mesenchymal stem cells for 7 days. Cel adhesion, growth, proliferation and stroma secretion were observed. RESULTS AND CONCLUSION:At 4 weeks after surgery, a strong inflammatory reaction was detected around materials in four groups. At 12 weeks, the xenogeneic bone materials prepared through physical and physical-chemical combined methods and hydroxy apatite biological ceramic materials internal pore and surrounding tissue inflammation disappeared basical y, with the presence of thimbleful inflammation cells. The material degradation was more than at 8 weeks. The xenogeneic bone materials prepared through chemical methods material internal pore and surrounding tissue inflammation stil existed, suggesting that the xenogeneic bone materials prepared through physical and physical-chemical combined methods exhibited good histocompatibility. A smal amount of orderly osteoblasts existed around hydroxy apatite biological ceramic materials and physical-chemical prepared materials, with a smal amount of bone. These suggested that there was a tendency for ectopic bone formation. The xenogeneic cancel ous bone materials prepared through physical or physical-chemical combined methods have better cytocompatibility. However, scaffold materials prepared through chemical method have poor cytocompatibility and they are not qualified for the safety standards of biological materials.

Objective:To investigate Bcl-2 and Bax gene expression in acute myelogenous Leukemia and the relationship between Bcl-2/Bax ratio and drug resistance.Method:Expression of Bcl-2、Bax was detected by immunohistochemical method while drug resistance of AML was detected by cell culture and MTT assay.Results:A high expression of Bcl-2 and a low expression of Bax were detected in AML,respectively,and the ratio between Bcl-2 and Bax was significantly higher than that in normal control (P＜0.01). The ratio in those who are resistant to chemotherapy was significantly higher than that in those sensitive to chemotherapy (P＜0.05).The responsiveness to chemotherapy of those with a high ratio was poorer than thos with a low ratio (P＜0.05).Conclusion:The alteration of Bcl-2 and Bax played certain role in the development of drug resistance in AML,the test of Bcl-2/Bax ratio may have great significance in choice of chemotherapeutic agents and also provide important information for outcome prediction.

OBJECTIVE To investigate the drug sensitivity situation of Acinetobacter baumannii(ABA) in 3 years to instruct clinical application of the antibiotics.METHODS The drug sensitivity test data of the 428 A.baumannii(ABA) strains from 2006 to 2008 were analyzed retrospectively.RESULTS It was showed from the drug sensitivity test in vitro that the most sensitive drug for A.baumannii(ABA) was imipenem,which resistance rate was 11.3-34%.The resistance rate to amikacin was 29.8-49.5% and to penicillins was is 57.7-91%,the resistance rate to of penicillins drugs was 54-74.5%.The resistance of ABA to ampicillin,cefazolin,cefpodoxime and Cefoxitin was over 91%,and showed the multi-drug resistance features.CONCLUSIONS According to the result of drug sensitive test,the most effective antibiotics are imipenem,meropenem and polymyxin B sulfate.

The conduction of performance appraisal in the hospital is of great significance to the perfection of the appraisal system and the improvement of the managerial efficiency of the hospital. The authors suggest that in the process of establishing an appraisal system of hospital performance, it is necessary to use for reference enterprises' experience in performance appraisal and the theories of performance management. Firstly, single-faceted pursuit of economic benefits should be avoided, the establishment of an external hospital appraisal system and the establishment of an internal hospital appraisal system should be combined, and attention should be paid to the overall application of performance appraisal in performance management. Secondly, in light of their own experience in hospital management, the authors put forward the suggestion of establishing a performance appraisal system of three levels: the hospital , the department and the post. They also argue that attention should be given to the selection of comprehensive appraisal methods, continuous communication about performance, and readjustment in a timely manner.

BACKGROUND: The conical telescopic crown denture has a better long-term effect on dentition defects of few remaining teeth than the traditional removable denture. However, there are few studies to analyze the application of these two kinds of repair methods using the finite element method. OBJECTIVE: To compare the stress distribution of the isolated abutment tooth repaired using the conical telescopic crown denture and traditional removable denture. METHODS: Two-dimensional images of the mandible and dentition in healthy adults were scanned by CT. Three-dimensional finite element models of conical telescopic crown denture and traditional removable denture were established in the mandible only with the bilateral canines. Under the same vertical and oblique loadings, the maximum equivalent stress of the abutment, periodontal membrane or edentulous alveolar ridge was compared between two repair methods. RESULTS AND CONCLUSION: Under the vertical and oblique loadings, the total stress of abutment and periodontal membrane in the traditional removable denture was higher than that in the conical telescopic crown denture and the stress in the corresponding ring was concentrated obviously; the total stress of edentulous alveolar ridge in the conical telescopic crown denture was slightly larger than that in the traditional removable denture, but the stress was wel -distributed and concentrated in a smal area. Under the oblique loading, the total stress of abutment, periodontal membrane and edentulous alveolar ridge was higher than that under the vertical loading in these two dentures, and the stress was concentrated in the periodontal membrane of lingual neck, but the total stress in the traditional removable denture was larger, with a wider concentration range. These findings indicate that the stress on the supporting tissue of conical telescopic crown denture is more evenly distributed within a smal er range than that of traditional removable denture, and the former is more fit for the health of abutment, periodontal tissues and edentulous alveolar ridge.

BACKGROUND: Hydroxyapatite/β-tricalcium phosphate biphasic ceramic bone has good cel compatibility, but its mechanical properties are poor. OBJECTIVE: To construct chitosan/ or calcium alginate/biphasic ceramic bone scaffolds and to detect their mechanical properties and cytocompatibility. METHODS: Different concentrations of chitosan (2%, 4%, 7%, 10%) or calcium alginate (3%, 4%, 5%, 7%) were mixed with biphasic ceramic bone to prepare chitosan/biphasic ceramic bone scaffold and calcium alginate/biphasic ceramic bone scaffold. Their morphology and structure, coagulation time, anti-dissolution properties, shear force, compressive strength and cel compatibility were detected. RESULTS AND CONCLUSION: (1) Coagulation time: with the concentration increase, the initial and final setting time of these two kinds of composite scaffolds were prolonged to some extent. (2) Scanning electron microscopy: these two kinds of composite scaffolds showed porous microstructures with different pore sizes. (3) Anti-dissolution properties: the calcium alginate/biphasic ceramic bone scaffold (3%, 4%, 5%, 7%) and chitosan/biphasic ceramic bone scaffold (7%, 10%) had good anti-dissolution properties in the liquid. (4) Mechanical strength: with the concentration increase, the shear force and compressive strength of the calcium alginate/biphasic ceramic bone scaffold were reduced. (5) Cel compatibility: the cytotoxicity of chitosan/ or calcium alginate/biphasic ceramic bone scaffolds was graded as 0-1 or 2-3, respectively. These results show that the chitosan/biphasic ceramic bone scaffold has better mechanical properties and cel compatibility than the calcium alginate/biphasic ceramic bone scaffold.

BACKGROUND:Xenogeneic bone structure and biological characteristics are similar to human bone tissue, and the xenogeneic bone has a decreased antigenicity after physicochemical treatment, with a natural porous structure and rich source, and can be kept for a long time, which is considered to be an effective way to solve the shortage of the autogenous bone and al ograft bone.
OBJECTIVE:To compare the physical and chemical properties of xenogenic bone materials prepared by two different methods.
METHODS:Sheep cancellous bone treated with chemical method was placed into the muffle furnace at 1 000 ℃for 2 hours to prepare calcined bone. Another cancellous bone was placed into an 80 ℃ refrigerator for 4 weeks and then placed into a vacuum instrument to prepare freeze-dried bone. Cancellous bone rinsed with ultra-pure water served as controls.
RESULTS AND CONCLUSION: Three groups of samples retained three-dimensional porous structure which similar with human bone tissue under microscopic observation. The framework was stil intact, with a smal pore of 55-650μm and high porosity of 65%-80%. For the calcined bone, the toughness was decreased and the brittleness increased significantly, but the freeze-dried bone had a little changes in the mechanical properties. Through diffraction analysis, hydroxyapatite was the main composition of the three groups. However, there was a smal amount ofβ-tricalcium phosphate in the calcined bone. Spectrum analysis confirmed that calcium and phosphorus content in these three groups were al close to the human body. The results suggest the cancellous bone treated with these two methods is similar to human bone structure, and the major elements are close to the body. In addition, the cancellous bone after processing has enough smal pore and higher porosity. However, calcination process has a more influence on the mechanical property of scaffold materials, and the freeze-dried bone has a little change but the antigen cannot be completely removed that can reach the basic requirements.

BACKGROUND:Many in vivo and in vitro experiments indicate that implantation of exogenous basic fibroblast growth factor can significantly promote the process of bone formation, but the in vivo degradation of exogenous basic fibroblast growth factor affects the therapeutic efficacy.
OBJECTIVE:To observe the effects of basic fibroblast growth factor-transfected mesenchymal stem cells which transfected using molecular biology techniques combined with al ogeneic bone in the repair of critical-size bone defects in sheep.
METHODS:Al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells, bone marrow mesenchymal stem cells combined with al ogeneic bone material stents, al ograft bone material,β-tricalcium calcium material were respectively implanted into critical-size bone defects in sheep. After 4, 8 and 12 weeks, histological and immunohistochemical staining was performed.
RESULTS AND CONCLUSION:At 12 weeks after implantation of al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells as tissue engineering bone, there were many cartilage-like structures in the operative binding region and a large amount of osteoblast-like cells in the center of operative region, and there was more material degradation in the entire operative area as compared with other groups;there were fibrous connective tissues ful of the pores, and osteoclast-like cells were commonly seen around the implant material;bone sialoprotein and col agen type Ⅰ expression were strongly positive. In the other three groups, although the cartilage-like structure appeared in the binding region, dead bone structure was found in the central area, and bone sialoprotein and type Ⅰ col agen expression was weak. These findings indicate that al ogeneic bone with basic fibroblast growth factor-transfected bone marrow mesenchymal stem cells can basical y repair critical-size bone defects in sheep.

BACKGROUND: Due to dentition defect, dentition loss, periodontal disease, trauma and tumor, many patients have to face insufficient buccal-lingual mandibular width. At present, there is no consistent conclusion in suitable peri-implant buccal-lingual mandibular width. OBJECTIVE: To investigate the stress of implant-bone interface with three-dimensional finite element method, in order to evaluate buccal-lingual mandibular width suitable for implants. METHODS: Classes Ⅰ and Ⅲ mandible implant models (the buccal-lingual width of implant neck region was 1, 1.5, 2, 2.5, 3 and 3.5 mm) were loaded with 200 N forces vertical y and at 60° oblique. Then, the stress and strain in the implant-bone interfacial were analyzed. RESULTS AND CONCLUSION: Almost 2 mm or more than 2 mm of mandible bone width could result in good stress distribution in implant-bone interface. The stress distribution of oblique loading was much greater than that of vertical loading. Proper quantity of peri-implant mandibular width is good for stress distribution in implant-bone interface. In the clinical treatment, the oblique loading should be avoided or reduced.

BACKGROUND:Some studies have indicated that different genes in tooth germ tissue play a role at different time, contributing to tooth germ development.
OBJECTIVE:To observe the expressions of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 at different stage of in vitro culture of tooth germ cells.
METHODS:RNA from tooth germ cells was extracted at days 1, 3, 6 of in vitro culture. After reverse transcription, real-time quantitative PCR detection was adopted to measure relative expression of dentin matrix protein 1, enamel protein, col agen I and homeobox gene 1 mRNA.
RESULTS AND CONCLUSION:Dentin matrix protein 1, enamel protein, and col agen I mRNA expressions increased with culture time, and reached the peak at day 3 (P<0.05), whereas homeobox gene 1 mRNA decreased with culture time (P<0.05).