Objective To investigate the regulatory effect of fluid shear stress(FSS) on the proliferation and differentiation of osteoblasts,as well as the expression of apoptosis-inducing factor,SIVA-1.Methods The third-passage osteoblasts were divided into five experiment groups and one control group.In the experiment groups,1.2 Pa FSS were given to the osteoblasts for 0.25,0.5,1,2,and 4 hours respectively,while the control group received no FSS.Afterwards,the cells were harvested to measure MTT value and ALP activity;mRNA level of SIVA-1 were determined by RT-PCR.Results MTT revealed that the cells proliferation markedly increased in the 0.25 h and 0.5 h experiment groups with advanced cell growth curve;whereas significantly inhibited in 1,2,and 4 h groups.The FSS also increased the ALP activity at 0.25 and 0.5 hour,especially in the 0.5 h group(2.4320?0.205 S unit/100ml,158% of the control;P

[Objective] To investigate into the cellular mechanism of growth promotion due to shear stress by studying G1-phase events responsible for the suppression of cell transition from the G1 to S phase of the cell cycle,and to establish the most suitable physiological stress to stimulate bone formation.[Methods]The osteoblasts derived from Kunming murine's calvaria were exposed to Fliud shear stress(FSS:12 dyn/cm2)for 0,0.25,0.5,1,2,4 h,respectively.In the flow chamber,its impact on cell proliferation,differentiation and the effection of cell cycle's G1/S checkpoint were recorded.The cell proliferation was studied by MTT assay.The cell differentiation was assessed through alkaline phosphatase(ALP)activity assay.Flow-cytometry,immunofluorescence and RT-PCR techniques were used to evaluate the proportion of S phase in cell cycle,the activity of CDK2,CDK4 and the expression of E2F-1,p27mRNA,which demonstrate how FSS underlying multiple mechanisms to enhance the cell cycle progression from G1 to S phase.[Results]FSS increased proliferation and advanced the time in cell growth curve,but after 1,2,4 h,the proliferation was inhibited.The FSS also increased the ALP activity,which were significantly stimulated at 0.25 and 0.5 h after shear stress(128% and 158 % of control);but the FSS decreased ALP activity at 1,2,and 4 hs.The proportion of S phase in cell cycle raised within the early period.The S phase rate significantly increased at 0.5 h(P

BACKGROUND: Bone marrow mesenchymal stem cells are prospective used in cartilage tissue engineering due to easy acquire and plentiful amplification in vitro in a short term.OBJECTIVE: To summarize the application of bone marrow mesenchymal stem cells in repairing cartilage defect.RETRIEVAL STRATEGY: A computer-based online search was conducted in Pubmed for English language publications containing the key words of "marrow; mesenchymal stem cells; cartilage defect" from October 1982 to December 2006, Relevant data were also searched in China Scientific and Technological Achievement Database for Chinese language publications containing the key words of "marrow; mesenchymai stem cells; cartilage defect" from October 1982 to December 2006. There were 126Exclusion criteria: duplicated articles.LITERATURE EVALUATION: Literatures including reviews and experimental studies were mainly derived from Pubmed database and China Scientific and Technological Achievement Database.DATA SYNTHESIS: It has been proved that bone marrow mesenchymal stem cells could differentiate into cartilage in vivo.However, differentiation of cartilage phenotype in vitro was restricted by multiple factors, and the controlling mechanism is still unclear up to now. Animal experiments demonstrated that bone marrow mesenchymal stem cells could repair bone and cartilage defect. Although studies on bone marrow mesenchymal stem cells and cartilage tissue engineering have developed to a certain degree, clinical applications and evaluations, including cell marks of bone marrow mesenchymal stem cells in different differentiated stages, controls of proliferation and differentiation of bone marrow mesenchymal stem cells, and gene transfection technique, still need a further study.CONCLUSION: Animal experiments indicate that bone marrow mesenchymal stem cells can significantly repair bone and cartilage defect. Although studies on bone marrow mesenchymal stem cells and cartilage tissue engineering have developed to a certain degree, problems of bone marrow mesenchymal stem cells in basic and clinical researches still need to be solved further.

Objective: To investigate the antitumor actions of polysaccharide extracts from the fruiting body of coriolus versicolor (CVE). Methods:Hepatoma HepA cells were injected into mice subcutaneously. Different doses of CVE were given by gavage. On the 7 th and 14 th day, tumor inhibitive rates were calculated. ELISA was performed to measure the serum IgG level; MTT was used to examine CVE′s effects on the proliferation of T lymphocytes of thymus. Immunohistochemistry was used to determine CVE′s influence on the expression of tumor related genes P53 and VEGF in liver. Results: CVE may evidently inhibit the growth of the transplanted HepA tumors. Its effects on the serum IgG level and on the proliferation of T lymphocytes of thymus were also significantly. Also, CVE markedly decreased the expression of P53, VEGF genes in liver. Conclustion: CVE had significant antitumor effects in vivo . The mechanisms may involve immune modulation effects and antimetastasis actions.

BACKGROUND: There is still no affirmative conclusion on the proliferative characteristics and the sources of neural progenitor cells after chronic compressive injury of spinal cord in adult mammals and the effects of astrocytes in this process.OBJECTIVE: To investigate the proliferative characteristics and the sources of neural progenitor cell and the effects of astrocytes by means of analyzing the changes of expression of nestin and glial fibrillary acidic protein after chronic compressive injury of spinal cord and after decompression in adult rats.DESIGN: Completely randomized control trial.SETTING: Orthopaedics Research Institute, the Second Hospital of Lanzhou University.MATERIALS: The experiment was completed in Orthopaedics Research Institute of the Second Hospital of Lanzhou University from March to October 2003. A total of 50 adult healthy Wistar rats were selected and randomly divided into normal control group, moderate chronic compressive spinal cord injury group (compressive mass occupied 40% of the diameter of spinal canal), severe compression group (compressive mass occupied 60% of the diameter of spinal canal). Three-day and 10-day decompression groups (depression after 24-hour severe compressive injury) with 10 in each group.MAIN OUTCOME MEASURES: ① Grey value of positive expression of nestin in grey and white matter in spinal cord segment near compression (5 mm to the edge of compression) in rats of each group. ② Expression of glial fibrillary acidic protein in spinal cord of rats in each group.RESULTS: All the 50 rats entered experimental analysis. ①There were significant expressions of nestin in moderate compression group (white matter 235.33±6.48, grey matter 196.28±6.55), severe compression group (white matter 190.45±4.91, grey matter 173.15±5.98), 3-day decompression after severe compressive injury group (white matter 198.39±3.24, grey matter 180.38±4.51) and 10-day decompression group (white matter 202.55±3.54) (P ＜ 0.05), especially in severe compression group (P ＜ 0.01).Compared with the normal control group, the difference between the ex pression of nestin in grey matter and that in ependymal cells on the central canal of spinal cord in 10-day decompression group has no significance (P ＞ 0.05). ②Compared with normal control group, the expression of glial fibrillary acidic protein in spinal cord increased in each injury group,and the amount of positive cells of glial fibrillary acidic protein went up and cell soma was hypertrophic, and the processes became thicker and longer.CONCLUSION: There is neural progenitor cell proliferation in the early stage of chronic compressive injury of spinal cord and after decompression in adult rats. Astrocyte participates in proliferation and migration of neural progenitor cells and has important trophic and repair effects on spinal cord.

Objective To investigate the effect of CDT1 gene over-expression on the apoptosis and cell cycle distribution in liver cells with a characteristic of genomic instability induced by radiation(GIR).Methods Lentivirus particles were transferred into liver cells of GIR to up-regulate the expression of CDT1 gene.The apoptosis and the cell cycle were detected by flow cytometry (FCM).The expression changes of p53,ATM,ATR,Bcl-2,and Caspase-3 genes were analyzed by real-time fluorescence quantitative PCR.Results CDT1 gene was efficiently increased by the gene transfection(t =15.56,P ＜ 0.05).In the CDT1 over-expressed cells,while the apoptosis ratio was increased (t =4.19,P ＜ 0.05),the expressions of p53 and Bcl-2 gene were decreased (t =-4.21,-2.06,P ＜ 0.05),but the expression of ATM,ATR and Caspase-3 changed with no significant difference compared with control.Conclusions Over-expression of CDT1 could regulate genomic instability through apoptosis pathway and checkpoint independent of p53.

Objective To investigate effects of exogenous sonic hedgehog (Shh) on proliferation of neural stem cells (NSCs) in ependymal area and recovery of motor function after spinal cord injury (SCI) in adult rats.Methods Fifty-five female SD rats were involved in the study:five were selected as normal control group and fifty as Shh group (n =25) and SCI group (n =25) after being subjected to SCI at T10 segment using the modified Allen' s method according to the random number table.At 1,3,7,14,and 28 days after operation,restoration of hindlimb motor function of SD rats was assessed with modified Tarlov scale and changes of double positive cells of Brdu and Nestin with double-stained immunofluorescence.Results Tarlov scale revealed statistical difference between Shh and SCI groups since days 7 postoperatively (P ＜ 0.05).In the double-staining test,number of double positive cells of Brdu and Nestin was greater in Shh Group than in SCI Group since day 3 postoperatively [(97.20 ± 18.23) vs (72.60± 15.60),(153.60 ±25.76) vs (112.20 ±23.63),(133.80 ±21.02) vs (94.20± 18.70),(89.80 ± 15.42) vs (43.40 ± 10.62),P ＜ 0.05].Conclusion Exogenous Shh is conducive to the proliferation of ependymal NSCs and the recovery of motor function in SCI rats.

Objective To investigate the muhilineage differentiation potential of bone marrow-derived mesenchymM stem eels (MSCs) in patients with systemic lupus erythematosus (SLE).Methods Density gradient centrifugation and plastic adherence methods were used for isolation of marrow-derived MSCs.Then tIIeir differentiation potentiality to lipoblasts and osteoblasts waft tested.MSCs loading on hydroxyapatite were elnbedded in the nude mouse's subcutaneous tissues.Eight weeks later.osteogenesis was evaluated by HE staining.PPA Rγ2,LPL,Runx2/CBFA1,osteocalcin gene expression in MSCs after differentiation were examined by RT-PCR.Results The positive rates of lipoblasts stained by oil red O and optical density in SLE were decreased than in the control group[(35±7)% vs (80±5)%] (0.14±0.04 vs 0.27±0.04),and the positive rates of osteoblasts stained by Alizarin Red S in SLE were decreased than those in the control group [(35±4)% vs (45±4)%].Osteoblast differentiation in the SLE group was less than that of the contro]group.The mRNA expression of LPL (0.369±0.020 vs 0.481±0.038).Runx2/CBFA1 (0.371±0.000 vs 0.563±0.069).osteoealcin (0.819±0.023 vs 0.962±0.049) of MSCs after difierentiation in the SLE group was decreased than that of the control group.There was no significant difference in the expression of PPARγ2 mRNA between SLE and controI group (0.421±0.052 vs 0.441±0.012).Conelusion MSCs from SLE have abnormalities in osteogenie and adipogenic differentiation potential.

To accommodate the requirement of quality education and achieve the goal of the 7-year-schooling clinical medicine,experimental training of cell immunology based on pathogen-induced immunology was established in combination with traditional experiment teaching method.In this course,inductive teaching method was used.The independent study and innovation ability of student were trained,which had a better teaching effect.

BACKGROUND:Several researches have highlighted the selective dissolution of Ni ion from the nickel-titanium (NiTi) alloy during the corrosion process,which can lead to potential damage to human body.Different surface treatments will improve the corrosion resistance of NiTi implants.In modern medicines,it is necessary to analyze the characteristics of surface modified NiTi implants.OBJECTIVE:To study the effects of coated and uncoated materials made by elastic nickel-titanium alloy internal fixator on fracture healing and to compare the effects of continuous compressive stress after internal fixator of different types on fracture healing by setting up control group of bone nail internal fixation.DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment was performed at the Laboratory of Tissue Engineering,Institute of Orthopedics,Second Hospital Affiliated to Lanzhou University between September 2004 and March 2005.MATERIALS:Diamond-like carbon coated and nickel-titanium alloy and uncoated nickel-titanium alloy embracing fixator (type 4H8-40) were provided by Lanzhou Ximai Memory Co.,Ltd.,China.Intramedullary nails (type ZQY-01) were purchased from Tianjin Jinxingda Industries Co.,Ltd.,China.METHODS:Thirty Chinchilla rabbits of 4-6 months old were randomly divided into 3 groups (n = 10):diamond-like carbon coated nickel-titanium alloy embracing fixator (group A),uncoated nickel-titanium alloy embracing fixator (group B),and intramedullary fixator (group C).Following anesthesia by injection of 1% sodium pentobarbital (25 mg/kg),transverse fracture models in middle part of the femur were made through a lateral femoral incision and fixed with diamond-like carbon coated nickel-titanium alloy embracing fixator,uncoated nickel-titanium alloy embracing fixator,and intramedullary fixator respectively.MAIN OUTCOME MEASURES:The inorganic substance level,osteocalcin,alkaline phosphatase (ALP) and tumor necrosis factor (TNF) expression in callus surrounding fracture site were detected 4 weeks postoperatively.Ni ion level in muscles surrounding fracture site,live tissue,and brain tissue were also detected.RESULTS:Inorganic substance level and ALP,osteocalcin,and TNF expression were significantly higher in the groups A and B than in group C (P＜0.05).Ni ion level in the liver tissue,brain tissue,and muscles surrounding the fracture were significantly lower in the groups A and C than in group B (P＜0.05).CONCLUSION:Elastic fixation promotes fracture healing.Diamond-like carbon coated nickel-titanium alloy embracing fixator has a better histocompatibility than uncoated group.