Effects of different organic solvents on slow-release recombinant human bone morphogenetic protein-2 microcapsules / 中国组织工程研究

BACKGROUND:In literatures, the recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded microcapsules can be fabricated by double emulsion solvent evaporation method with different organic solvents, such as methylene chloride, ethyl acetate or their mixture. But so far it is not determined yet which one is better. OBJECTIVE: To optimize the preparation method of microcapsules encapsulating rhBMP-2 and to compare the effects of different organic solvents on the microcapsules. METHODS:Polylactic acid-polyethylene glycol-polylactic acid copolymer as microcapsules was used to prepare rhBMP-2 loaded microcapsules with double emulsion solvent evaporation method. Four kinds of organic solvents, methylene chloride (group A), mixture of methylene chloride and ethyl acetate (group B), ethyl acetate (group C) and acetyl acetone (group D) were chosen as oil phases to compare their effects on microcapsule's morphology, diameter, and encapsulation efficiency. Passage 3 bone marrow mesenchymal stem cels from rats were co-cultured with prepared microcapsules for 14 days, and then alkaline phosphatase activity was detected. RESULTS AND CONCLUSION:Compared with the other organic solvents, dichloromethane could cause microcapsules with the smaler and more uniform shape (4-10 microns) and the highest encapsulation efficiency; the microcapsules prepared by mixture of methylene chloride and ethyl acetate had relatively wide size distribution and moderate encapsulation efficiency; the microcapsules prepared by acetylacetone were difficult to form and keep the bioactivity of rhBMP-2. After cultured with rat bone marrow mesenchymal stem cels for 14 days, the alkaline phosphatase activity in groups A, B and C was significantly higher than that in group D and there was no significant difference between group A and group B; the alkaline phosphatase activity in groups A and B was significantly higher than that in group C (P< 0.05). The results show the rhBMP-2-loaded microcapsules prepared by methylene chloride as organic solvent have good shape, high encapsulation efficiency, and good biological activity.

Analysis of risk factors of nonspecific low back pain in a community population: a case-control study / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the risk factors of nonspecific low back pain in community populations.</p><p><b>METHODS</b>Two community populations were investigated using questionnaires in this case-control study. The questionnaire was designed to collect data including age, gender, body weight, marriage, education, income, occupation, labor intensity, smoking, alcohol drinking and social mental status. The subjects with low back pain constituted the case group and those without low back pain served as the control group, and the data was analyzed by a Logistic regression model.</p><p><b>RESULTS</b>A total of 1747 community residents participated in this survey, among whom 398 subjects had low back pain and 1126 subjects without low back pain were selected as the control group. Of all the latent risk factors of low back pain in Logistic regression model, gender was the most relevant factor (OR=3.5522) followed by education (OR=1.958), labor intensity (OR=1.956), marital status (OR=1.612), vibration source exposure (OR=1.491), BMI (OR=1.127) and age (OR=1.060).</p><p><b>CONCLUSION</b>Gender, education, labor intensity, marriage, vibration source exposure and BMI are risk factors of nonspecific low back pain in community populations, and exercises and mental status can be protective factors against low back pain.</p>

Posterior fixation and fusion for treatment of Os odontoideum complicated by atlantoaxial dislocation / 南方医科大学学报

<p><b>OBJECTIVE</b>To summarize the techniques and evaluate the therapeutic effect of posterior fixation and fusion in the treatment of Os odontoideum complicated by atlantoaxial dislocation.</p><p><b>METHODS</b>From March, 2007 to October, 2010, 10 patients with Os odontoideum (including 6 male and 4 female patients aged from 20 to 65 years, mean 39.8 years) were treated in our hospital. Before and after the operation, the patients underwent X ray, CT and MRI examinations to measure and evaluate the degree of dislocation and neural compression. After preoperative traction for 1-2 weeks, all the 10 patients showed deductible atlantoaxial dislocation. Through a posterior approach, Atlantoaxial pedicle screws fixation were performed in 9 cases, and C2/3 pedicle-Occiput screw fixation was performed in 1 case. All the patients wore cervical collars as external support for 3 months after the operation.</p><p><b>RESULTS</b>The mean operative time was 3 h in these patients with a mean intraoperative blood loss of 420 ml. The symptoms were relieved after the surgery in all the patients, who showed no neck pain or neurological defects. The patients were followed up for 6 to 52 months (mean 22 months), and bony fusion was observed in all the 10 cases within 6 to 8 months without such complications as internal fixation failure or redislocation of the atlas.</p><p><b>CONCLUSION</b>Patients with Os odontoideum complicated by atlantoaxial dislocation should undergo surgical stabilization to avoid severe neurological injury. Pedicle screw instrument in the atlas allows restoration of the spinal stability, short-segment fusion, and maximal preservation of the mobility of the neck.</p>

Effects of rehabilitation training combined with bone marrow mesenchymai stem cell-derived neural stem cells transplantation on the expression of Nogo-A and NgR proteins after spinal cord injury / 中华物理医学与康复杂志

Objective To study the effects of rehabilitation training combined with the transplantation of bone marrow mesenchymal stem cells-derived neural stem cells (BMSC-D-NSCs) on the expression of Nogo-A and NgR protein in rats after spinal cord injury (SCI).Methods The spinal cords of eighty Sprague-Dawley rats were injured using a modified Allen′s impactor (H = 25 mm) at T10. The injured rats were randomly divided into a combination therapy group which was given rehabilitation training and cell transplants, a cell graft group, a rehabilitation training group and a control group. At the 7th day post SCI, BMSC-D-NSCs were transplanted into the injured spinal cords of the rats in the combination therapy and cell graft groups. Hindlimb movement was assessed using the BassoBeattie-Bresnahan (BBB) scale every week, and protein was extracted from the injured spinal cord tissue for Nogo-A and NgR determination by Western blotting at the 1st, 3rd and 7th day after cell transplantation.Results The average BBB score of the rats in the combination therapy group was significantly higher than that of the other groups from 2 weeks post transplantation. The scores in the rehabilitation training group were significantly higher than in the control group from the 5th week post transplantation. Western blotting showed high expression of Nogo-A and NgR protein 24 h post surgery, but these declined with time. For Nogo-A there was a significant difference among the groups at all three time points. In the combination therapy group the expression declined to a minimum by the 7th day. For NgR protein there was no significant difference between the 1st and 3rd day in any group.Conclusions Rehabilitation training combined with BMSC-D-NSC transplantation can have a synergistic effect on functional recovery from SCI. It can down regulate the expression of Nogo-A and NgR protein.

Chronic spontaneous cervicothoracic epidural hematoma in an 8-month-old infant

Spontaneous spinal epidural hematoma is an uncommon cause of cord compression in children, especially in infants. An 8-month-old infant was admitted to our hospital for a 40-day history of paraparesis in the lower extremities. This rapidly progressed to paraparesis with an inability to move the lower extremities. MRI of the cervicothoracic spine revealed an epidural mass with compression of the spinal cord. The infant underwent C7-T3 total laminectomies. The pathology and postoperative MRI confirmed spinal epidural hematoma from a vascular malformation. We present the case to highlight the significance of recognizing this chronic spontaneous spinal epidural hematoma and discuss the diagnosis, treatment options and prognosis

Degradable performance and bio-mineralization function of PLA-PEG-PLA/PLA tissue engineering scaffold in vitro and in vivo / 生物医学工程学杂志

The degradable performance and bio-mineralization function of PLA-PEG-PLA/PLA tissue engineering scaffolds in vitro and in vivo were systematically studied. The X-ray diffraction and Fourier transform infrared spectra showed that there was the deposition of bone-like carbonate hydroxyapatite on the surface of scaffolds. We found that the weight of scaffolds did not always decrease with the prolongation of time in vitro. At the same time, we found that after the PLA-PEG-PLA/PLA tissue engineering scaffolds were embedded in skulls of rhesus monkeys, the new bone area reached 75% at the 12th week. Histological observation showed that the new bones were rebuilt and knitted bones were formed at the 12th week. These findings meant that the PLA-PEG-PLA/PLA tissue engineering scaffolds were potential in clinical use.

Biomechanical studies of single segmental spinal interbody fusion with bisegment fixation for thoracolumbar burst fracture type B / 中国组织工程研究

BACKGROUND: Thoracolumbar burst fracture Dennis type B does not have significant damage in the intervertebral discs of the inferior vertebral body. To reduce fusion segment and remain normal intercalated disc, single discectomy (damaged vertebral body and supervisor vertebral body) is proposed, but because of the damage to the vertebral body, implanted screw is easy to loose following excising partial vertebral body, even cannot be fixed. However, it is still unknown whether implanted screw in the inferior vertebral body of the damaged vertebral body was stabilized using two segment discectomy with fixation.OBJECTIVE: To analyze the feasibility of single segmental spinal interbody fusion with bisegment fixation for thoracolumbar burst fracture type B.DESIGN, TIME AND SETTING: The randomized controlled in vitro study was conducted at the Laboratory of Biomechanics, Southern Medical University from June 2007 to June 2008.MATERIALS: A total of 20 fresh freezing 7-9 months pig samples (T_(13)?L_3 segment) were used, comprising 10 integral samples and 10 L_1 type B thoracolumbar burst fracture samples prepared by pre-injury and weight dropping technique.METHODS: Pig fresh thoracolumbar specimens from T_(13)?L_3 were collected to create models of type B thoracolumbar burst fracture. There were 4 groups in this study. Ten of them were selected as intact group (n=10) (fresh pig T_(13)?L_3 segment). T_1 vertebral endplate pre-injury and weight dropping technique and incremental trauma approach were used. Denis' type B burst fracture was produced, and ten of them were selected as unstable group (n=10). Firstly, unstable group was decompressed by discectomy and semivertebraectomy in upper half of the vertebral body, single level was fused with iliac and U-FRONT anterior thoracolumbar system were placed between T_(14) and L_2, as single discectomy with fixation group (n=10). Then lower disc of injury vertebra discectomy and vertebraectomy, fused with iliac U-FRONT anterior thoracolumbar system were placed between T_(14) and L_2, as two segment discectomy with fixation group (n=10). The bone graft was longer 1 mm than the bone graft region.MAIN OUTCOME MEASURES: The flexion, extension, right/left lateral bending, and right/left axial rotation range of motion (ROM) of T_(14)?L_2 were measured in each group on the spinal three-motional test machine at 10 N穖.RESULTS: The flexion, extension, right/left lateral bending, and right/left axial rotation were not stable in the unstable group.ROM was significantly increased in the unstable group compared with the intact group (P< 0.01). The primary stability was significantly elevated in the single discectomy with fixation and two segment discectomy with fixation groups. The flexion, extension, right/left lateral bending, and right/left axial rotation ROM were significantly reduced in the single discectomy with fixation and two segment discectomy with fixation groups compared with the unstable group (P < 0.05). The flexion, extension, right/left lateral bending ROM was significantly decreased in the two groups compared with the intact group, but axial rotation ROM was significantly increased (P< 0.05). Axial rotation ROM was smaller in the single discectomy with fixation group compared with the two segment discectomy with fixation group (P < 0.05).CONCLUSION: Single segmental spinal interbody fusion with bisegment fixation for thoracolumbar burst fracture type B had a good immediate stability in flexion, extension, lateral bending motion. Compared with traditional partial corpectomy L_1 between the caudal and cranial endplate of the adjacent vertebrae with bisegmental fixation, it had a better immediate stability in axial rotation.

Compatibility research of three-dimensional bioactive glass/rhBMP2 materialscaffolds / 中国矫形外科杂志

[Objective]To investigate the compatibility of tissue and cell in the three-dimensional porous bioactive glass/recombine human Bone Morphogenetic Protein-2 (BG /rhBMP2)materialscaffolds and provide a reference for improving the constitution of composite material.[Method]The material of BG and BG/rhBMP2 were cultured in vitro with rabbit osteoblasts respectively. The morphology and adhesion were examined by inverted microscope and scanning electron microscope, and the cell proliferation was detected by MTT assay. The composite materialscaffold were embeded in rabbit's muscle and incisions were observed. The specimens were harvested in 2, 4, 8 and 12 weeks respectively and examined by histology to evaluate the tissue response.[Result]The results showed the cells on BG and BG /rhBMP2 were good adhension and activity, the two materialscaffolds had no apparent inflammatory reaction in vivo. MTT assay showed the number of the cells in each group were significantly increased along with the culture time prolonged. The number of cells in the BG and rhBMP2 group was higher than that of the control group at different intervals, with a significant difference. The number of cells in the BG/rhBMP2 was not evidently higher than that of the BG with a significant difference.[Conclusion]The porous composite materialscaffold of BG/rhBMP2 has good biocompatibility with the hope to wide use in bone tissue engineering.

Experience of the Orthopedic Clinical Teaching of the Interns of Medical Science of Law / 中华医学教育探索杂志

The experience in the orthopedic teaching of the interns of medical science of law was explored.The features of the students of the medical science of law were analyzed.And related teaching project was established during the progress of orthopedic practice.Our experience emphasized on the knowledge teaching of medical ethics and medical disputes.

Gene expression of two kinds of constitutive nitric oxide synthase in injured spinal cord tissue / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the gene expression of two kinds of constitutive nitric oxide synthase (cNOS): neuronal NOS (nNOS) and endothelial NOS (eNOS) in injured spinal cord tissue.</p><p><b>METHODS</b>Thirty-six adult Sprague-Dawley rats were divided randomly into six groups: the normal group and the injury groups (2, 6, 12, 24, 48 h after injury, respectively). A compression injury model of the spinal cord wa s ma de and gene expression of nNOS and eNOS were examined by reverse transcription polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>The gene expression of nNOS and eNOS was detected in the normal group and they were up-regulated quickly after injury, reaching the maximum at 6 h. There was no difference between gene expression of nNOS and eNO S in the normal group, but in each injury group the gene expression of eNOS was much higher than that of nNOS.</p><p><b>CONCLUSIONS</b>Expression of constitutive NOS (cNOS) in spinal co rd tissue was up-regulated after injury mainly in the early stage. cNOS as a wh ole offers protection in spinal cord injury, but different cNOS may play different roles.</p>

STUDIES ON DEGRADATION OF THREE-DIMENSIONAL POROUS POLY-DL-LACTIDE/HYDROXYAPATITE COMPOSITES IN VITRO / 解放军医学杂志

To investigate the degradation features of HA and PDLLA/HA composites in different proportion in vitro. Four kinds of foams consisting of PDLLA, PDLLA/HA (5%wt), PDLLA/HA (20%wt), and PDLLA/HA (35%wt) were immersed in distilled water. Changes in pH, mass loss, viscosity-average molecular weight, and strength against pressure were observed and compared to study degradation features of specimens in vitro. There were statistically differences in the indexes between the PDLLA/HA (20%wt) composite and the other foams after 12 weeks (P

Experimental study of optimized bioactive glass by osteoblasts differentiated from rabbit bone marrow mesenchymal stem cells / 中国医师杂志

Objective To investigate the growth of rabbit osteoblast on the composite bioactive glass material scaffolds and to explore the experimental methods of optimized material scaffolds in bone tissue engineering. Methods The mesenchymal stem cells(MSCs) were separated and cultured from rabbit thigh marrow,and they were induced and differentiated into osteoblast by the revulsant.The change of typical appearance of the MSCs was investigated under microscope.The cytological characteristics of the MSCs were observed through cells activity and immunohistochemistry method.The osteoblast was cocultured with three various bioactive glasses respectively.The compatibility between the various bioactive glasses and osteoblast was compared by observation of the changes of the cells.Results The MSCs were successfully induced and cultured in the presence of the osteoblast revulsant.After inducement,these cells displayed osteoblast-like morphology.The bioactive glass composite scaffolds supported the attachment of cultured rabbit osteoblast.These cells proliferated faster on scaffolds with higher poriness of 90.20% and 94.50% than with lower poriness of 75.90%.Conclusion It is feasible to use bioactive glass composite scaffolds with proper poriness for bone tissue engineering.