Objective:To investigate the feasibility of establishing a canine model of lumbar intervertebral disc degeneration through the application of cumulative axial load and a six-phase combined motion on the vertical sitting dog's lumbar spine.Methods:Twenty adult female grass dogs, each weighing 10.0±0.5 kg, were randomly divided into two groups, with 10 dogs in each group. In the model group, dogs were secured to an exercise machine in a vertical position, and six phases of lumbar spine movement (flexion and extension, left and right lateral flexion, left and right rotation, 45° each) were combined with a specific number of cycles under continuous axial load (245 N). In the control group, dogs were secured to the exercise machine in a vertical position without any intervention. Radiographic examinations were performed before and after 20,000, 50,000, 100,000, and 150,000 compound exercises in the model group. The disc height index (DHI) was measured through lateral X-ray, and MRI T2-mapping was used for quantitative analysis of intervertebral disc degeneration. When intervertebral disc degeneration was evident on MRI T2-weighted imaging (modified Pfirrmann system > Grade V), the combined motion was halted. Micro-CT quantitative analysis of bone mineral density (BMD) in the upper and lower endplates, trabecular bone structure, and histological staining (HE staining, "O" staining, Sirius red staining) were employed to verify and assess the degree of intervertebral disc degeneration.Results:After 50,000 compound exercises, mild degeneration of the intervertebral discs at L 6-7 and L 7S 1 was observed on T2-weighted imaging. With the accumulation of exercise load, the degree of degeneration progressively increased, reaching a moderate degree of degeneration after 100,000 composite exercises, and DHI began to decrease. Mild degeneration was also observed in the upper L 5-6 intervertebral disc. When the cumulative exercise volume reached 150,000 repetitions, the height of intervertebral spaces in the L 5-6, L 6-7, and L 7S 1 segments further decreased, and the intervertebral discs exhibited severe degeneration (improved Pfirrmann grading system Grades IV-VI). The upper L 4-5 intervertebral discs also displayed mild degeneration. Histological scores were as follows: L 5-6 (8.2±0.8), L 6-7 (9.5±0.7), and L 7S 1 (10.3±0.5), indicating a degree of degeneration in the order of L 5-6

Objective To observe the effect of different explosion impulse on rabbit lung injury and decide the death curve,so as to provide a reference for the prediction of lung injury.Methods Six healthy male New Zealand white rabbits with weight of 2.0-2.5 kg and age of (6 ± 1)months were selected.The rabbits were put 0.5 m,0.6 m,0.7 m,0.9 m,1.0 m,and 1.2 m away from 90 g TNT to carry out the blast injury experiment.The characteristic parameters of blast shock wave and general lung injury were recorded.Based on the experimental results combined with theoretical analysis,the changes of rabbit lung injury depending on the explosion distance as well as the rabbit death curve were determined.Results After the 90 g TNT explosion,the peak overpressure of shock wave and the corresponding specific impulse decreased quickly with the increase of explosion distance.The peak overpressure was 0.79 MPa and the specific impulse was 82 Pa · s at the explosion distance of 0.5 m.The peak overpressure was 0.1 MPa and the specific impulse was 34 Pa · s at the explosion distance of 1.2 m.The rabbits at 0.5 m and 0.6 m died,the rabbit at 0.7 m was severely injured,and the rabbits at 0.9 m,1.0 m,and 1.2 m were slightly injured.The dependence of lung injury degree on the explosion distance under 90 g TNT explosion was established based on dimensional analysis theory.The lung injury degree was exponentially attenuated with the explosion distance:φ =(R/0.6)-5.64(φ represented lung injury degree,and R represented the explosion distance).Considering the combined injury effects of peak overpressure of shock wave and its specific impulse on rabbit lung,the death curve of rabbit was determined:(p-0.1) (I-59) =2.6 (p represented peak overpressure,and I represented specific impulse).The criterion of "overpressure-specific impulse" was used to estimate the death of rabbit,and the death curve of rabbit was determined as (p-0.1)(I-59) =2.6(p represented peak overpressure and I represented specific impulse).The critical overpressure was 0.1 MPa and the critical specific impulse was 59 Pa · s.Conclusions Under the explosion condition of 90 g TNT,the relationship between degree of lung injury in rabbits and explosion distance is established.Death curve of rabbits is determined based on the damage effect of shock wave peak overpressure and specific impulse on the lungs of rabbits,which is significant for predicting the blast injury.

Objective To compare the effects of preserving the posterior ligament complex (PLC) with torque loading and displacement loading on the biomechanical properties of the adjacent segments after lumbar decompression and fusion. Methods Six fresh male cadaver lumbar specimens of T12-S2 were tested in the sequence of intact, L4-5 laminotomy (preserving the PLC) with fixation and L4-5 laminectomy (destructing the PLC) with fixation, by applying both displacement loading and torque loading, respectively. Ranges-of-motions (ROMs) of the adjacent segments were measured under a noncontact photographic recording system. Results In displacement-loading mode, the flexion ROM in laminectomy group was significantly higher than that in laminotomy group, and no obvious ROM differences were found in the laminectomy and laminotomy groups under extension, lateral bending, and rotation movement. Conclusions Torque loading and displacement loading have different biomechanical effects on the adjacent segments after lumbar decompression and fusion. Compared with the laminotomy method, in which the PLC is preserved, the laminectomy method in which PLC structures are damaged can obviously lead to an increment of flexion ROMs at the adjacent segments, and also increase the ROMs of the adjacent segments under extension, lateral bending, and rotation movements, which might increase the risk of further instability of the fused adjacent segments.

Intervertebral disc degeneration (IVDD) takes great affection on people health all over the world.With the extension of human life and aging,the number of sick people will grow rapidly.At present,both conservative and surgical treatment can only alleviate the symptoms,rather than the fundamental treatment for the process of degeneration.Therefore,the application of cell therapy in the treatment of degenerative disc regeneration is an innovative treatment.However,it's a great bottleneck for exogenous transplanted stem cells to survive in degenerated intervertebral disc with harsh environment containing strong force,acidic pH,hypoxia,hyperosmolarity and limited nutrition.In recent years,tissue endogenous repair has been demonstrated to be present in almost all human tissues,and endogenous stem cell play an important role in the process.Similarly,nucleus pulposus was also confirmed the existence of such a kind of tissue specific stem cells-nucleus pulposus derived stem cells (NPSCs)-a new promising candidate for the treatment of IVDD.NPSCs,as a new kind of stem cells,hold either the characteristic of stem cell and the special potential of themselves,such as the nice adaption of the environment in intervertebral disc and the superior potential of cartilage differentiation.Nonetheless,the isolations of NPSCs were different;cell phenotypes were lack of wildly acceptable standard and the biological characteristics were various among different NP sources.In addition,whether the application of NPSCs could be used in nucleus pulposus tissue engineering still calls for further research.Due to the unclear in degeneration mechanism of IVDD,the study on degeneration mechanism of NPSCs may play a great important role in clarifying this issue.

A finite element model of cervical spine was three-dimensionally reconstructed through computed tomography (CT) scan, recording the edges of image using Snigraphics V18.0 software, and calibrating in sequence of point, line, area, and solid. The stress distribution of cervical C_(3-4) was analyzed using compute aided design to validate the availability of reconstructed models. Results showed that the three-dimensional finite element cervical C_(3-4) was feasible in simulation analysis. These indicate that the established three-dimensional finite element models can simulate biomechanical experiments, providing foundations for analyzing biomechanical performance of local structure of this finite element model under various pressure conditions.

Objective To analyze the reasons and therapeutic effects for revision of spinal fractures.Method Ninteen patients with revised internal fixation on spinal fractures were reviewed in average of 3.5 years follow-up. Neurological function, pain and daily life quality of patients with revision surgery were evaluated by questionnaire.ResultIncomplete spinal canal decompression as well as improper application of instrumentation were the main reasons of failed internal fixation for spinal fractures.All patients with incomplete spinal cord injury had improvement on neurological function to some extent after re-operation, and 17 of 19 patients (89%) indicated improved daily life quality. However, revision surgery failed to have motor recovery in patients with complete spinal cord injury.ConclusionCorrect surgical technique and selection of internal fixation are very important in the treatment of spinal cord injury.

[Objective]To investigate the clinical and histopathological characteristics of myofibrosarcoma,and study its treatment and prognosis.[Method]The clinical features,histopathological characteristics,diagnosis,treatment and prognosis of two rare myofibrosarcoma patients were observed,and relative literatures were reviewed.[Result]After biopsy,the frist patient was treated with amputation in her middle thigh.postoperative chemotherapy was performed in the local hospital,but the drug and its dose didn't know in detail.one year latter,the patient died because of lung metastasis.The second patient was treated with tumor resection,but three months latter,the tumor recurred and was resected again,and the patient accepted chemotherapy,eleven nonthns latter,lung metastasis was found.then the patient died.About 54 patients with myofibrosarcoma were found in the literatures published in recent years.This neoplasms often involved the head and neck region,trunk and extremities in male patient A expandable and painless mass is the chief clinical features.Myofibrosarcoma can be identified by its specific morphologic features and positive myoid markers.[Conclusion]Myofibrosarcoma is a rare spindle cell neoplasm,Its morbidity dosen't know in detail.When making diagnisis,it is important to distinguished from synovial sarcoma,fibrosarcoma and leiomyosarcoma et al,Surgical resection is the mainstay of therapy,but the result of chemotherapy is not affirmed,The tumor is lower grade malignant one,and is invadable.The rate of local recurrence is high,and distant metastasis could be found.Its prognosis is not affirmed.

0.05).The operating time in group A was 106?22.3 min,94.1?29.3 min in group B and 81.6?22.3 min in group C.There were no significant differences between group A and B,or between group B and group C,but there was significant difference(P=0.009) between group A and group C.The was Two cases of dura tear occurred at operatiom and one case was converted to open discectomy in group A.There were three cases of reoperation in group B.There were no intra-and postoperation complications in group C.[Conclusion]From the learning curve of lumbar microendoscopic discectomy,surgeons can master such skill only after performing 30 or more cases of lumbar microendoscopic disecetomy.

BACKGROUND: At present, genetic recombinant technique has been utilized to express recombinant human bone morphogenetic protein-2 (rhBMP-2)and to induce either orthotopic or ectopic regenerated bone successfully. But,because that osteoblastic activity induced by rhBMP-2 is lower than that by natural BMP-2, the perfect vectors have not been discovered yet.OBJECTIVE: BMP recombinant adenovirus (rAdV) was constructed so as to provide feasible vector for the basic treatment of bone defect.DESIGN: Single sample was designed in the experiment.SETTING: Experimental Center of Molecular Biology in First Hospital of Xi'an Jiaotong University.MATERIALS: PACCMV-PLPA plasmid, PJM17 plasmid, 293-cell line.METHODS: The experiment was performed in Experimental Center of Molecular Biology in First Hospital of Xi'an Jiaotong University from September 2001 to June 2002. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to clone the whole-length gene of BMP-2 and construct AdV vector. DNA-calcium phosphate coprecipitation was used to transfect accessory plasmid PJM17 into 293cell and homologous recombination was used to construct rAdV. The titer was assayed and CsC1 density gradient centrifugation and purification were applied.construction of rAdV.binant plasmid is named as pGEM-T/hBMP2, (3 015+1 213)bp in size.It was indicated in agar gel electrophoresis that the practical value was in BMP2 shuttle plasmid: The plasmid was about 10 Kbp in size. Since PACCMV-PLPA plasmid multiclone sites belonged to PUC plasmid series,EcoR Ⅰ enzyme digestion was used to linerarizate recombinant plasmid,10 Kbp in size. 8.8 Kb and 1.2 Kbp visible fragments were obtained durtion of rAdV: PCR technique was used to identify rAdV. The target fragment 1.2Kbp that was amplified by BMP2 specific primer of the whole length was in conformity completely with the theoretic value.CONCLUSION: Successful construction of BMP2 rAdV lays a foundation for the feasible genetic treatment with vector of bone defect.

Objective To investigate the biological effects of low intensity of pulsed ultrasound (LIPUS) on human periosteal cells and marrow stromal cells in vitro. Methods LIPUS of 30 mW/cm2 was used to stimulate the cultured human periosteal cells and marrow stromal cells for 5 min, 10 and 20 min per day, respectively, followed by the examination of cell proliferation and differentiation potential. Results Thymidine incorporation and total protein assay indicated that LIPUS had no significant effect on DNA and protein synthesis of the periosteal and marrow stromal cells, suggesting that LIPUS did not promote proliferation of these cells. However, ALP activity and osteocalcin secretion of the human periosteal cells were dramatically increased. Conclusion The results suggested that low intensity pulsed ultrasound stimulated periosteal cell proliferation and differentiation toward osteogenic lineage, this might contribute to the curing effect of low intensity pulsed ultrasound for fracture.