Objective To study artificial lumbar intervertebral disc three-dimensional finite element model and its stress state. Methods The three-dimensional finite element models of artificial lumbar intervertebral disc were established by finite element software MSC. MARK. While L4-5 motion segment from young healthy cadaver was created to give the models biomaterial characters. The vertebral disc of L4-5 was replaced by artificial lumbar intervertebral disc to make a model of an artificial disc replacement. Results After three-dimensional finite element models with biomaterial characters of artificial lumbar intervertebral disc and L4-5 motion segment had been created, the stress distribution of artificial lumbar intervertebral disc showed some characteristics as follows:1)The stress exerted in the center of polyethylene slide core and end plates is biggest in all motion states, the next exists at the deviated site while the polyethylene slide core set in motion. 2)The upper surface of polyethylene slide core and end plates bear 2-3 times stress as much as that of the lower surface. 3)The biggest stress exists in the center of polyethylene slide core and end plates during compression in all motion states. Conclusion Establishment of three-dimensional finite element models of artificial lumbar intervertebral disc and analysis of its stress are feasible. The results are reliable.

BACKGROUND:Bone marrow stromal stem cells(BMSCs)do not allow for single differentiation of chondrocytes due to their multi-directional differentiation,bone morphogenetic protein secreted from osteoblasts affect the non-differentiated precursor cells and promote their osteoblast differentiations,while those differentiated cells are bound to form tissues.OBJECTIVE:To in vitro induce canine BMSCs differentiate into chondrocytes,and to investigate the method and conditions of chondrocyte differentiation in vitro.DESIGN,TIME AND SETTING:Single sample observation was performed in the Laboratory of Tissue Engineering,Sun Yat-sen University between March 2005 and January 2006.MATERIALS:One male dog,aged 4 months,was involved to harvest BMSCs from the rib.METHODS:Rib BMSCs extracted from bone marrow of 2.0-3.0 mL were cultured in vitro. When cells reached a confluence at 8-11 days,trypsinization was conducted and then halted with L-DMEM synthesis culture solution containing 10% fetal bovine serum. Cellular suspension was collected and centrifuged,cells were rssuspended and incubated at a ratio of 1:3. The third generation of cells were cultured and amplified,10 μg/L basic fibroblast growth factor 2 mL was added to replenish culture medium twice,then 1 mg/L transforming growth factor β1 of 2 mL was applied to induce BMSCs differentiation into chondrocytes.MAIN OUTCOME MEASURES:Toluidine blue and alcian blue stains were applied to determine cartilage matdx secretion,immunohistochemistTy was used for the detection of cartilage specific Ⅱ collagen expression.RESULTS:After BMSCs were primarily cultured and subcultured in vitro,they were shown to grow well at the fourth generation,those induced by basic fibroblast growth factor and transforming growth factor β1 were positive for toluidine blue and aician blue staining;immunohistochemistry showed a positive outcome for type Ⅱ collagen,indicating the induced BMSCs exhibited chondrocyte's characteristics.CONCLUSION:Utilizing basic fibroblast growth factor and transforming growth factor β1,the induced canine BMSCs could differentiate into chondrocytes,which is considered as an ideal seed cells for cartilage tissue engineering.

BACKGROUND: Presently-used artificial intervertebral disk is different greatly from the normal physiological intervertebral disk in structure, material and biological properties and so on. Therefore, stress conduction at corresponding spinal section will have a certain change after the implantation of artificial intervertebral disk.OBJECTIVE: To investigate the stress distribution in small joints of normal intervertebral disk group, vertebral extirpation group and artificial lumbar intervertebral disk group with three-dimensional element method in order to discuss exploratorily the influence of the implantation of artificial lumbar intervertebral disk on the stress distribution in small joints.DESIGN: Observative and comparison experiment.SETTING: Orthopedic Department, Third Affiliated Hospital and Second Affiliated Hospital, Sun Yat-sen University; Biomechanical Laboratory in Southern Medical University.PARTICIPANTS: Spinal specimen collected from the healthy people who died in accidenct without any spinal illness (donated by their family member) was used to establish three kinds of three-dimensional element models of normal intervertebral disk, artificial intervertebral disk and vertebral extirpation as experimental subjects.METHODS: Finite element MSC.MARK software was used to establish normal intervertebral disk model with height of 10.00 mm, cross sectional area of 1300.00 mm2, and vertebral pulp cross sectional area of 495.8 mm2;in the model of vertebral pulp extirpation,the intrinsic pressure of vertebral pulp was zero; and in the three dimensional models of artificial lumbar intervertebral disk and L4-5 movement segment , the small joints were about 10.53 mm high with width of 13.37 mm and auricular area of 135 mm2.Then lumbar movement was simulated for the study of the stress distribution in small joint.MAIN OUTCOME MEASURES: Comparison of the stress in small joints under 6 kinds of states in the above three kinds of intervertebral disk movement model.RESULTS:In vertebral pulp extirpation group, the stress was proved to be the highest at superior edge, posterior middle part, lower edge and anterior middle part of small joints under anteflexion, backward extension, compression, lateroflexion and revolving states, moreover, small joint stress in artificial lumbar intervertebral disk was higher than that in normal intervertebral disk, but obviously lower than that in vertebral pulp extirpation group;however, the small joint of the middle part of artificial lumbar intervertebral disk bore the highest stress under revolving states.CONCLUSION: In contrast with vertebral pulp extirpation group, the small joint stress could be reduced after the implantant of artificial lumbar intervertebral disk, but was still higher than that of normal lumbar intervertebral disk group and the anti-verticity in artificial lumbar intervertebral disk group was markedly lower than that of normal lumbar intervertebral disk group and vertebral pulp ablation group, thus indicating that although presently-used artificial lumbar intervertebral disk possesses most of mechanical functions of normal lumbar intervertebral disk, but is still different from true lumbar intervertebral disk.

BACKGROUND: At present, there are very big differences in structure,material character and biological property between artificial intervertebral disc (AID) and normal physiological intervertebral disc.OBJECTIVE: Three-dimensional finite element method was used to observe and analysis the stress conduction of artificial lumbar intervertebral disc in lumbar motion segment.DESIGN: Single sample observation was designed.SETTING: Department of Orthopaedics, Third Affiliated Hospital, Sun Yat-sen University; Department of Orthopaedics, Second Affiliated Hospital, Sun Yat-sen University; Laboratory of Mechanics, Southern Medical UniversityPARTICIPANTS: It was to employ a vertebral sample without any spinal disorder of a healthy male died due to accidence and a finite element model of AID implantation in vertebral motion segment established with SB Charite Ⅲ AID.METHODS: According to industrial design chart of AID, finite element software MSC.MARK was utilized to establish three-dimensional model of artificial lumbar intervertebral disc. The corpus sample of motion segment of healthy lumbar vertebrae was collected and scanned with spiral CT machine and imaging documents were input in computer to preserve.Geometric model of L4-5 segment was established in three-dimensional coordinate system in ASC.MARK software. The intervertebral disc in L4-5 motion segment model was replaced by AID. It was to ensure the fixation of lower terminal lamina of L5 in the model. 4 Nm moment of force was exerted in anterior flexion, posterior extension, lateral bending and torsion on the sample successively. Finally, force of internodes representing AID was calculated and stress distribution was recorded.MAIN OUTCOME MEASURES: To observe stress distribution of anterior flexion, posterior extension, compression, lateral bending and rotation of AID.RESULTS: Finite element model of artificial lumbar intervertebral disc implanted lumbar motion segment that is in conformity with clinical practice was established. Stress distribution of AID was characterized as:er lamina was the maximum and that in the lower inclined part of slide of slide core and cover lamina was two or three times as same as that of sion, the stress in the center of slide core and cover lamina was the maximum.CONCLUSION: The finite element model of artificial lumbar intervertebral disc implanted lumbar motion segment established is in conformity with the structural character of practical artificial intervertebral disc in morphology, size and motion property, based on which, it is feasible to carry on the experiment on stress distribution of artificial intervertebral disc.

AIM: To establish HPLC fingerprint for the identification of Hydrocotyle sibthorpioides and its adulterants. METHODS: The chromatographic seperation was performed on a Diamonsil C_(18) (250 mm×4.6 mm,5 μm)with a mobile phase consisting of acetonitrile-0.1% phosphoric acid, gradient eluent, at the flow rate of 1.0 mL/min. The UV detection was set at 340 nm. RESULTS: There was an apparent difference in fingerprint between Hydrocotyle sibthorpioides and its adulterants. CONCLUSION: The method is stable and reliable with a good reproducibility andprovides a reference standard for identifying Hydrocotyle sibthorpioides and its adulterants.

BACKGROUND:Preliminary studies have showed that vacuum sealing drainage based on wound surface dressing biomaterials is a good method to cover the wound as succedaneous peau when the soft tissuedefects along with open fracture cannot be completely repaired during the first operation. OBJECTIVE:To explore the efficacy of vacuum sealing drainage based on wound surface dressing biomaterials in repair of soft tissue defects of foot and ankle. METHODS:Fourteen patients with soft tissue defects of foot and ankle were treated using free skin graft combined with vacuum sealing drainage technique. Meanwhile, the traditional skin graft after wound dressing changes was applied in another 11 patients. The clinical outcomes were compared between two groups. RESULTS AND CONCLUSION:The transplanted skin in 10 cases of the vacuum sealing drainage group survived. The total survival rate was 71%, and surgical dressing change was applied in the left four patients to finaly cover the wound. By comparison, the transplanted skin in four cases of the traditional group survived. The total survival rate was 54%. To finish the wound, three of the left patients were turned to surgical dressing change and two of them stil needed skin graft operation once more. The total survival rate between the two groups has no statistical significance(P > 0.05). The therapeutic procedure noted that the time waiting for the secondary surgical visit, times for dressing change before the second intervention and the time for final union between the two groups were statisticaly different (P < 0.05). So the vacuum sealing drainage based on wound surface dressing biomaterials may accelerate the repair of soft tissue defects of foot and ankle when using the free skin graft operation.

Objective To evaluate pit pattern analysis for detection of early colorectal carcinoma and precancerous lesions. Methods A total of 162 lesions in 144 patients were examined with magnifying colonoscopy after staining, and their pit patter was analyzed with morphology and pathologic diagnosis. Results With confirmation of pathology, there were 34 non-neoplastic lesions and 128 neoplastic ones, in which 12 were carcinomas. The pit patterns in most non-neoplastic lesions (76. 5%, 26/34) were type Ⅰ or Ⅱ , and those in most neoplastic lesions (96. 1% , 123/128) was type Ⅲ, Ⅳ or Ⅴ. Pit patterns of cancerous lesions were mainly type Ⅴ (75.0%, 9/12), and those of 3 cases of advanced cancers were all type Ⅴ N. Conclusion Pit pattern classification is a very important tool to differentiate between neoplastic, nonneoplastic lesions and early cancer, which helps to decide later therapeutic intervention.

AIM: To establish HPLC fingerprint for the identification of Hydrocotyle sibthorpioides and its adulterants. METHODS: The chromatographic seperation was performed on a Diamonsil C_18(250 mm?4.6 mm,5 ?m)with a mobile phase consisting of acetonitrile-0.1% phosphoric acid,gradient eluent,at the flow rate of 1.0 mL/min.The UV detection was set at 340 nm. RESULTS: There was an apparent difference in fingerprint between Hydrocotyle sibthorpioides and its adulterants. CONCLUSION: The method is stable and reliable with a good reproducibility and provides a reference standard for identifying Hydrocotyle sibthorpioides and its adulterants.

AIM:To evaluate the biocompatibility between copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and bone marrow stem cells (BMSCs). METHODS: Canine BMSCs were isolated and cultured. The cells in passage 3-4 were seeded onto the PHBV films and three-dimensional foams. The seeded cells were observed under inverted microscope for morphology and cell attachment onto the PHBV films at 1, 2 or 3 weeks after seeding. With 4% paraformaldehyde formalin and staining, the protein content in seeded cells was determined by bicinchoninic acid assay (BCA). The content of DNA was quantified using the Hoechst 33258 assay. RESULTS: Observation under inverted microscope showed that the PHBV fabric was fairly thickness, lucency is weak. Unser contrast phase microscope, PHBV fabric was uneasy to be observed. Most cells attached onto the PHBV films 2 h after seeding, and extended well and acquired a spindle fibrecyte-like morphology 3 d later. Moreover, on the three-dimensional foams, the seeded cells lay in micropores and grew tri-dimensionally. The conjunction of cells appeared about 1 week, and extended at 3 weeks, with a large amount of extracellular matrix around cells. The content of DNA and protein has no significant difference with control group. CONCLUSION: As a kind of tissue engineering material for BMSCs seeding, PHBV has an excellent biocompatibility.

BACKGROUND: Poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) is a novel scaffold made by solvent casting/particulate leaching procedure, composed of polyhydroxybutyrate and polyhyclroxyvalerate at certain ratio, which has good biocompatibility as well as high intensity and modulus. It has three-dimensional porous net structure and good biodegradation. OBJECTIVE: To evaluate the biocompatibility between copolymers of PHBV and canine bone marrow mesenchymal stem cells(BMSCs).DESIGN, TIME AND SETTING: In vitro comparative observation. The study was performed at the Laboratory of Histology and Embryology, Sun Yat-sen University between June 2003 and March 2004.MATERIALS: PHBV scaffold, film porosity > 85% and 100-350 μ m aperture size.METHODS: Canine BMSCs were isolated and cultured. The 3-4 passage cells were seeded onto the PHBV films and three-dimensional foam scaffold. Cells cultured alone served as control.MAIN OUTCOME MEASURES: The seeded cells were observed under inverted microscope; at 1, 2, 3 weeks after seeding, the BMSCs were treated with 4% paraformaldehyde and stained with hematoxylin-eosin (HE); The protein content in seeded cells was determined by bicinchoninic acid assay (BCA), and the content of DNA was quantified using Hoechst33258 assay at 5, 10, 14 days after culture.RESULTS: Inverted microscopic observation showed that the PHBV fibers were fairly thick with weak lucency, and the fibers were hardly detectable under contrast phase microscope. Majority of cells attached onto the PHBV films 2 hours after seeding, and extended well in a spindle shape at 3 days. One week after culture, 2 PHBV were fixed, and BMSCs proliferation was observed after HE staining. At two weeks, cells continued to proliferate and densely covered the PHBV film. The cells grew in the three-dimensional pores, connected at 1 week, extended at 3 weeks, secreting a large amount of material around cells. Cell proliferation did not change much at 3 weeks compared with 2 weeks, and there was no significant difference in DNA and protein contents between control and PHBV groups (P > 0.05).CONCLUSION: As a kind of tissue-engineered scaffold material for BMSCs, PHBV displays good biocompatibility.