Parathyroid hormone inhibits the apoptosis of osteoblast MC-3T3E1 cells through a non-PLC-dependent protein kinase C pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of the non-PLC-dependent protein kinase C (PKC) pathway of parathyroid hormone (PTH) on the apoptosis and proliferation of osteoblast MC-3T3E1 cells.</p><p><b>METHODS</b>MC-3T3E1 cells were seeded in 96-well plates at the density of 1.5×10(4) cells/mL and incubated for 3 day. The cells were then exposed to 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-28), 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-34), 100 nmol/L of [Gly(1), Arg(19)]hPTH(1-34)+1 µmol/L Go6983, 1 µmol/L Go6983, or deionized water (control) for 1, 24 or 48 h. After the treatments, cell counting kit-8 (CCK-8) and Caspase-Glo® 3/7 Assay (Caspase-3) were used to examine the proliferation and apoptosis of MC3T3-E1 cells.</p><p><b>RESULTS</b>CCK-8 results showed that hPTH(1-34) increased the number of MC3T3-E1 cells compared with hPTH(1-34)+Go6983 at 1 h and 24 h, but this difference was not statistically different. At 48 h, treatment with hPTH(1-34), as compared with hPTH(1-28), significantly increased the number of MC3T3-E1 cells (P<0.05), and this effect was blocked by the PKC inhibitor Go6983 (P<0.05). hPTH(1-34) did not result in significant inhibition of MC3T3-E1 cell apoptosis at 1 h and 24 h as compared with hPTH(1-34)+Go6983, but significantly inhibited the cell apoptosis as compared with hPTH(1-28) (P<0.05); this inhibitory effect was blocked by Go6983 (P<0.05).</p><p><b>CONCLUSION</b>s A relatively long time (for 48 h) of exposure to PTH can inhibit apoptosis and promote the proliferation of MC3T3-E1cells through a non-PLC-dependent PKC pathway.</p>

Teriparatide for conservative treatment of osteoporotic vertebral fracture: analysis of 12 cases / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the efficacy of conservative treatment with teriparatide for promoting bone fracture healing in patients with osteoporotic vertebral fracture.</p><p><b>METHODS</b>Twelve postmenopausal patients (aged 73±4.8 years) with osteoporotic spinal fracture confirmed by MRI or CT scanning received conservative treatment with teriparatidesc injection supplemented with calcium and analgesics for 6 months. At the beginning and at the end of the therapy, VAS score, Oswestry Disability Index (ODI), bone mass densitometry, and X-ray of the thoracic and lumbar spine, and serum P1NP and beta-CTX levels were measured. Six of the patients received a second MRI scan after the therapy to evaluate the bone healing.</p><p><b>RESULTS</b>All the 12 patients completed the treatment, during which no new fractures or adverse events occurred. At the end of the first month of treatment, analgesic was withdrawn for all the patients. The average VAS score decreased from 8±2 to 1±2 at 1 month during the therapy, and ODI was reduced from (76±12)% to (20±5)% at 1 month and further to (5±4)% at 6 month. After the 6-month therapy, the height of the fractured vertebrae (presented as the anterior to posterior wall height ratio) was insignificantly decreased from (75±20)% to (61±20)%, the BMD was increased by (20±5)%, P1NP increased significantly from 20.9±11.4 ng/mL to 80.0±41.2 ng/mL, and beta-CTX increased from 0.30±0.17 ng/mL to 0.51±0.3 ng/mL. The 6 patients re-examined with MRI demonstrated complete bone healing after the therapy.</p><p><b>CONCLUSION</b>Teriparatide is effective for conservative treatment of osteoporotic spinal fracture and can promote bone fracture healing, improve the quality of life, and prevents vertebral collapse, and can be therefore an alternative treatment to PVP or BV.</p>

Diagnostic value of enzyme-linked immunospot assay using CFP10/ESAT6 fusion protein as antigen in spinal tuberculosis / 中国医学科学院学报

<p><b>OBJECTIVE</b>To establish a method of detecting spinal tuberculosis (TB) infection by enzyme-linked immunospot (ELlSPOT) assay and evaluate the value of CFP10/ESAT6 fusion protein for diagnosis of spinal TB.</p><p><b>METHODS</b>Suspected spinal TB patients were prospectively recruited in two hospitals (First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine; Nanfang Hospital, Southern Medical University) from May 2012 to December 2013. Data on clinical characteristics of the patients and conventional laboratory results were collected. Compare and analyze the positive detection rate in spinal TB diagnosis by different methods including ELISPOT detection and conventional detection methods.</p><p><b>RESULTS</b>47 patients with spinal TB had available biopsy or surgical specimens for histopathological examination and 41 specimens had pathological features consistent with a diagnosis of TB infection. Among the spinal TB patients and non-TB disease patients,the overall sensitivity, specificity, positive predictive value, and negative predictive value of the ELISPOT assay in spinal TB diagnosis were 82.7%,87.2%,89.6%, and 79.1%,respectively; the 4 indexes of the PPD skin test were 61.5%, 46.2%, 60.4%, and 47.4%, respectively;those of the antibody detection were 55.8%, 61.5%, 65.9%, and 51.1%. The positive rate of ELISPOT was significantly higher than those of PPD skin test and antibody detection test (82.7% vs. 61.5%, Χ² =5.786, P=0.016; 82.7% vs. 55.8%, Χ² =8.847, P=0.003), but not significantly different from the positive rate of pathological examination (82.7% vs. 87.2%, Χ² =0.396, P=0.529). Moderate agreement was found between pathological examination and the ELISPOT assay (87.2%, Κ=0.498, P=0.001).</p><p><b>CONCLUSION</b>With high sensitivity and specificity, the ELISPOT assay using CFP10/ESAT6 fusion protein as antigen is an effective technique for auxiliary diagnosis of spinal TB.</p>

Advances in clinical application and biomechanical studies of the posterior dynamic transpedicular screw fixation system / 医用生物力学

It is known that rigid pedicle screw fixation may cause abnormal stress concentration on the posterior part of the spine, which may lead to stress concentration on the fixation device; meanwhile, due to the motion limitation to the fixed segment, the excessive motion at the adjacent segment may further fortify the disc degeneration. To solve these issues, the dynamic fixation is used in clinic, and many studies have investigated the biomechanical mechanism and clinical outcome of the dynamic fixation. The ideal dynamic fixation should meet the following conditions: offering enough stabilization for the fixed segment; reducing the load on the fixation device through enhancing the strain on the anterior vertebral bodies; preventing the degeneration at the adjacent segment; controlling the horizontal shear force at the fixed segment. In this article, the biomechanical properties and clinical application of the posterior dynamic fixation were reviewed and the biomechanical mechanisms of different dynamic fixations were compared.

Repair of critical size bone defects with porous poly [D,L-lactide]/nacre nanocomposite hollow scaffold

To generate a novel porous poly[D,Llactide]/nacre nanocomposite hollow scaffold. This study was performed in the Department of Spine Surgery, Southern Medical University, Guangzhou, China from September 2010 to September 2011. Nacre nanoparticles were prepared using a physical process and identified by x-ray diffraction and transmission electron microscopy, to generate a novel scaffold though the salt leaching processing technique. The morphology and structure properties of this scaffold were further investigated under scanning electron microscope and mechanical property testing. Additionally, the biological characteristics were evaluated by cell culture experiments in vitro. Thirty-six rabbits were randomly divided into 3 groups. The defects were implanted with/without poly[D,L-lactide]/nacre scaffold or poly[D,L-lactide] scaffold. The results were assessed by radiographs and bone mineral density to monitor bone repairing. The nacre nanoparticles were spherical in shape, with a diameter range from 45-95 nm. The scaffolds possessed an interconnected porous structure with an average pore size of 322.5 +/- 50.8 micro m, and exhibited a high porosity [82.5 +/- 0.8%], as well as good compressive strength of 4.5 +/- 0.25 Mpa. Primary biocompatibility experiments in vitro showed that cells adhered and proliferated well on the scaffolds. The animal study further demonstrated that the scaffolds could repair the critical size segmental bone defects in 12 weeks. Newly established scaffolds may serve as a promising biomaterial for bone tissue engineering.

Effects of bioactive modification of poly-D,L-lactide acid scaffolds on the biological behaviors of the seed cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the changes in the biological behavior of bone marrow mesenchymal stem cells (BMSCs) transfected with red fluorescent protein by lentivirus (RFP-BMSCs) seeded on in poly-D, L-lactide acid (PDLLA) scaffolds with bioactive modification by ammonia plasma and Gly-Arg-Gly-Asp-Ser (GRGDS) in vitro.</p><p><b>METHODS</b>Circular sheets of PDLLA scaffolds (8 mm in diameter and 1 mm in thickness) were prepared and aminated with PDLLA (group A) or modified with the peptide conjugate A/PDLLA (group PA), with untreated PDLLA as the control (group P). The RFP-BMSCs were seeded on the scaffold materials and their proliferation and metabolic activity were detected using CyQuant NF and Alamar blue staining. The mineralization on the scaffolds was observed using calcein fluorescent dye under a fluorescent microscope. The adhesion and proliferation of RFP-BMSCs were observed by fluorescent microscope, and scanning electron microscope (SEM) was used to confirm the observed adhesion of the seed cells.</p><p><b>RESULTS</b>The RFP-BMSCs seeded on the 3 scaffolds all showed proliferative activity at different time points after cell seeding, and the cell numbers decreased significantly in the order of PA>A>P (P<0.001). The cell number was significantly greater in group PA than in group A at all the time points except for days 10 (P=0.077) and 12 (P=0.491), and gradually became similar with the passage of time. The metabolic changes of the cells follow a similar pattern of cell proliferation. RFP-BMSCs showed more active proliferation in group A and group PA than in group P. On days 14 and 21, the intensity of green fluorescence decreased in the order of group PA, A and P. The RFP-BMSCs showed better adhesion in group PA than in group A, and the cells in group P appeared more scattered under scanning electron microscope.</p><p><b>CONCLUSION</b>Bioactive modification of PDLLA by ammonia treatment and conjugation with GRGDS peptides may promotes the adhesion, proliferation, metabolism and mineralization of RFP-BMSCs seeded on PDLLA scaffolds.</p>

Histology and proliferative capability of thoracic vertebral body growth plates of rats at different ages / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the histological features of the thoracic vertebral body growth plates (VBGPs) of rats at different ages and assess their proliferative capability.</p><p><b>METHODS</b>The thoracic VBGPs obtained from rats aged 1 day and 1, 4, 8, 16 and 28 weeks were identified using safranin O-fast green staining, and the height of the hypertrophic zone, proliferative zone, and resting zone were measured. The chondrocytes were isolated from these VBGPs with a modified trypsin-collagenase type II digestion method for primary culture in vitro. The expressions of proliferating cell nuclear antigen (PCNA) mRNA and protein was detected by real time-PCR and Western blotting, respectively.</p><p><b>RESULTS</b>The 1-day- and 1-week-old rats showed significantly greater hypertrophic zone and proliferative zone in the VBGPs than older rats (P<0.01); the proliferative zone was significantly greater in rats aged 4 weeks than in those aged 28 weeks (P<0.05). The resting zone was obviously greater in rats aged 1 day and 1 week than in older rats (P<0.05), and also greater in rats aged 4 weeks than in those aged 16 and 28 weeks (P<0.05). Obvious ossification in the resting zone occurred at 16 weeks, and most of the resting zone became ossified at 28 weeks. The expression of PCNA decreased at both the mRNA and protein levels as the rats grew.</p><p><b>CONCLUSION</b>The 3 zones of VBGPs are greater in rats aged 1 day and 1 week than in older ones. Ossification in the resting zone begins at 16 weeks, and till 28 weeks, most of the resting zone is ossified. The proliferation ability of VBGP chondrocytes decreases with the increase of age of the rats.</p>

Over-expression of platelet-derived growth factor-BB in degenerative hypertrophied ligamentum flavum / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of platelet-derived growth factor-BB (PDGF-BB) in the degeneration of the hypertrophied ligamentum flavum (LF) in the lumbar spine.</p><p><b>METHODS</b>Surgical specimens of degenerative hypertrophied LF were obtained from 11 patients with lumbar spinal stenosis (LSS, mean age 57.8 years), with those from 10 age-matched patients with lumbar disc herniation (LDH, mean age 53.5 years) as the normal controls. The thickness of the LF was measured preoperatively by axial T1-weighted magnetic resonance imaging (MRI) at the facet joint level. Immunohistochemistry was employed to determine the expression of PDGF β and PDGF-BB in the LF. The mRNA and protein expressions of PDGF-BB in the LF were detected using real-time PCR and Western blotting, respectively.</p><p><b>RESULTS</b>The thickness of the LF was 5.30±1.12 mm in the degenerative group and 2.80±1.53 mm in the control group, showing a significant difference between the two groups (P<0.001). PDGF-β and PDGF-BB were positive in the fibroblasts in hypertrophied LF. The mRNA and protein expressions of PDGF-BB were significantly higher in the degenerative group than in the control group (P=0.013 and 0.023, respectively).</p><p><b>CONCLUSION</b>The high expression of PDGF-BB in the hypertrophied LF suggests its important role in the development of hypertrophy of LF in lumbar spinal canal stenosis.</p>

effect of leptin on the osteoinductive activity of recombinant human bone morphogenetic protein-2 in nude mice

To investigate the effect of leptin in the model of ectopic bone formation that utilizes subcutaneously implanted recombinant human bone morphogenetic protein-2 [rhBMP-2]-containing type I collagen discs. This study was performed in the Clinical Research Center, Southern Medical University, Guangzhou, China from November 2008 to June 2009. A single dose of 20 micro l saline [group A], 20 micro g leptin [group B], 2 micro g rhBMP-2 [group C], 2 micro g rhBMP-2 + 20 micro g leptin [group D], and type I collagen disks as a carrier were mixed, and subcutaneouly implanted into the back of nude mice [n=12]. The effect of ectopic bone formation was evaluated by radiography, dual energy X absorptiometry, biochemical examination of alkaline phosphatase [ALP] activity, histological observation, and semi-quantitative evaluation 4 and 8 weeks after surgery. At 4 and 8 weeks after operation the radiographs, bone mass density, ALP, and histology values showed significant intragroup and intergroup differences, with those at 8 weeks being higher than those at 4 weeks. Our results indicated that the sustainedly released material with collagen as a carrier combined treatment with leptin and rhBMP-2 has a very good osteoinductive activity. Leptin is a positive modulator for the osteoinductive efficacy of BMPs, they have synergistic effect. Its mechanisms are probably related to promote the formation of new-vessels and proliferation/ differentiation of many kinds of cells

Complications of the anterior surgical approach for thoracolumbar spine tuberculosis: causes and countermeasures / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the effect of the anterior surgical approach for thoracolumbar spine tuberculosis and analyzed the causes of the surgical complications and the countermeasures.</p><p><b>METHODS</b>From Jan 1996 to Dec 2005, 120 patients with thoracolumbar spine tuberculosis underwent operations through the anterior approach either following the primary diagnosis (115 cases) or for recurrence (5 cases).</p><p><b>RESULTS</b>Intraoperative pleural rupture occurred in 4 cases, and rupture of the external iliac vein occurred 1 case. Three patients had damages of the T12 dorsal ramus. One patient developed venous embolism of the lower extremity after the operation, two had paralytic ileus and 1 had false diabetes insipidus. Of the 5 recurrent patients, 1 died due to alcoholic cirrhosis and acute liver failure, 1 received a third operation for loosened internal fixation, and 1 had recurrence due to extensive drug resistance (XDR).</p><p><b>CONCLUSION</b>Standardized antituberculous therapy is fundamental for preventing the recurrence of tuberculosis, and individualized antituberculous therapy adjustment according to the results of bacterial culture and drug sensitivity tests can be the most effective means for preventing drug resistance and reducing tuberculosis recurrence.</p>

MTT assay for detecting osteosarcoma cell apoptosis / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the feasibility of using MTT assay for detecting the apoptosis of osteosarcoma cells following chemotherapy.</p><p><b>METHODS</b>The osteosarcoma cells derived form surgical specimens were cultured in RPMI 1640 medium supplemented with 10% calf serum. Chemotherapeutic agents were administered in the cell culture, and MTT assay was used to observe the cell apoptosis under optical microscope.</p><p><b>RESULTS</b>MTT staining accurately identified apoptosis of the osteosarcoma cells, and the apoptotic cells were easily distinguished from normal cells and dead cells.</p><p><b>CONCLUSION</b>MTT staining is convenient and practical for detecting osteosarcoma cell apoptosis.</p>

Nacre-induced osteogenesis in the femoral condyles of New Zealand rabbits / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate nacre powder-induced osteogensis in the femoral condyles of New Zealand rabbits and investigate the possible mechanism.</p><p><b>METHODS</b>Nacre powder was implanted into the femoral condyles of New Zealand rabbits and 4, 8, and 12 weeks after the implantation, radiographic examinations were carried out and the bone density was evaluated. The bone tissue specimens were sliced after fixation for histological observations. The osteogenesis area on the slice was estimated with Ponceau Red staining 8 and 12 weeks after the implantation and calculated with Imaga-Pro software.</p><p><b>RESULTS</b>X-ray after the operation did not reveal obvious evidence of angiogenesis in the femoral condyles, where the X-ray density underwent slight changes. The optical density decreased significantly after the implantation, and the quantity of the osteoid, woven and lamellar bone increased in the bone tissue with time. The osteogenesis area with Ponceau Red staining showed obvious bone formation, which was significantly different from the control group.</p><p><b>CONCLUSION</b>T Obvious osteogenesis occurred in the femoral condyles after nacre powder implantation in New Zealand rabbits. Nacre powder has slow biodegradation in vivo and induces osteogenesis by osteoinduction.</p>

Overexpression of transforming growth factor-beta1 in degenerative ligamentum flavum / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of transforming growth factor (TGF)-beta1 in degeneration of the ligamentum flavum in the lumbar spine.</p><p><b>METHODS</b>The degenerative ligamentum flavum was obtained during surgery from 8 patients with lumbar spinal stenosis (mean age 58.6 years), and 8 young patients (mean age 24.2 years) with acute lumbar disc herniation were included as normal controls. The thickness of the ligamentum flavum was measured on preoperative magnetic resonance images, and the mRNA expressions of type-I collagen and TGF-beta1 in the ligamentum flavum were detected using reverse transcriptase-polymerase chain reaction. The protein expression and localization of TGF-beta1 were investigated by Western blotting and immunohistochemical staining, respectively.</p><p><b>RESULTS</b>The thickness of the ligamentum flavum were 4.70-/+0.40 mm in the degenerative group and 2.50-/+0.36 mm in the control group, showing significant difference between the two groups (P<0.001). The type-I collagen mRNA expression in the degenerative group was significantly higher than that in the control group (P=0.007). The mRNA and protein expressions of TGF-beta1 were significantly higher in the degenerative group than in the control group (P=0.008 and 0.004, respectively). Immunohistochemistry showed that TGF protein was localized in the fibroblasts within the ligamentum flavum.</p><p><b>CONCLUSION</b>Degenerative ligamentum flavum shows hypertrophy and fibrosis, and TGF-beta1 overexpression may be associated with in the development and progression of ligamentum flavum degeneration in the lumbar spine.</p>

A rapid colorimetric assay for viability of osteosarcoma cells after chemotherapy / 南方医科大学学报

<p><b>OBJECTIVE</b>To introduce a rapid colorimetric method for assessing the viability of osteosarcoma cells after chemotherapy.</p><p><b>METHODS</b>Colorimetric assay and automatic microplate scanning spectrophotometer were used for assaying the viability of osteosarcoma cells.</p><p><b>RESULTS</b>Close correlation was found between the absorbance at 570 nm of the formazan products and the number of viable osteosarcoma cells.</p><p><b>CONCLUSION</b>An effective, sensitive and convenient colorimetric assay has been established to assess the survival of osteosarcoma cells following chemotherapy.</p>

Leptin expression by heterotopic ossification-isolated tissue in rats with Achilles' tenotomy

To set up heterotopic ossification [HO] models according to McClure and determine whether leptin messenger ribonucleic acid [mRNA] and protein are expressed in HO-isolated tissue. This study was performed in the Department of Spine and Orthopedics, Southern Medical University, Guangzhou, China from November 2007 to June 2008. Thirty-six male rats were randomly divided into sham, partial achilles' tenotomy [PAT], and achilles' tenotomy [AT] groups, with 12 rats in each group. X-ray and histological examination were carried out to ensure the formation of HO at 5 and 10 weeks after operation. Specimens from achilles tendons and surrounding tissue were taken and processed. Meanwhile, the expression of leptin mRNA [5 and 10 weeks] and protein [10 weeks] in achilles tendons and the surrounding tissue were examined respectively using reverse transcription-polymerase chain reaction assay and immunohistochemical methods. There were no leptin mRNA and protein expression in the sham and a weak expression in the PAT of Achilles tendons and surrounding tissue, whereas there was strong expression in the AT group. Leptin is involved in the formation of HO, its mechanisms is related to induction of bone formation and maturation through a series of cellular events, including: proliferation/differentiation of many kinds of cells, collagen synthesis, mineralization, and vascularization of the extracellular matrix

Phenotypic Characterization of Ligamentum Flavum Cells from Patients with Ossification of Ligamentum Flavum

PURPOSE: The objective of this study was to determine the phenotypic characterization of ligamentum flavum cells from patients with ossification of the ligamentum flavum (OLF). MATERIALS AND METHODS: Ligamentum flavum tissues were harvested from OLF and non-OLF patients during surgery. OLF and non-OLF cells were isolated from explant cultures. Cultured cells were analyzed using immunofluorescence staining and reverse transcription-polymerase chain reaction. RESULTS: OLF cells exhibited various appearances compared with the typical fibroblast-like morphology of non-OLF cells. Expressions of collagen type I and collagen type III were observed in OLF and non-OLF cells. OLF cells uniquely expressed osteocalcin, which is a marker for osteoblasts, and collagen type II which is a marker for chondrocytes, whereas they were negative in non-OLF cells. CONCLUSION: These findings indicate that OLF cells have phenotypic characterization of osteoblasts and chondrocytes which could play a role in the pathophysiology of OLF.

Risk factors of secondary kyphotic angle increment after veterbroplasty for osteoporotic vertebral body compression fractures / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the risk factors of secondary kyphotic angle increment after bone cement vertebroplasty for osteoporotic vertebral compression fractures.</p><p><b>METHODS</b>From October 2005 to May 2006, 32 (45 vertebrae) bone cement vertebroplasty procedures were performed. The operation time, injected cement volume, bone mineral density, visual analog scale (VAS) pain score, vertebral height, and kyphotic angle were recorded. The secondary increment of the kyphotic angle was calculated, and correlation analysis and linear regression analysis were performed.</p><p><b>RESULTS</b>The bone mineral density, the postoperative kyphotic angle and the vertebral midline height were significantly correlated to the secondary increment of the kyphotic angle.</p><p><b>CONCLUSION</b>Large postoperative kyphotic angle, poor postoperative recovery of the vertebral midline height, and low bone mineral density are all risk factors of secondary increment of the kyphotic angle.</p>

Preparation of nano-nacre artificial bone / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the improvements in the properties of nano-nacre artificial bone prepared on the basis of nacre/polylactide acid composite artificial bone and its potential for clinical use.</p><p><b>METHODS</b>The compound of nano-scale nacre powder and poly-D, L-lactide acid (PDLLA) was used to prepare the cylindrical hollow artificial bone, whose properties including raw material powder scale, pore size, porosity and biomechanical characteristics were compared with another artificial bone made of micron-scale nacre powder and PDLLA.</p><p><b>RESULTS</b>Scanning electron microscope showed that the average particle size of the nano-nacre powder was 50.4-/+12.4 nm, and the average pore size of the artificial bone prepared using nano-nacre powder was 215.7-/+77.5 microm, as compared with the particle size of the micron-scale nacre powder of 5.0-/+3.0 microm and the pore size of the resultant artificial bone of 205.1-/+72.0 microm. The porosities of nano-nacre artificial bone and the micron-nacre artificial bone were (65.4-/+2.9)% and (53.4-/+2.2)%, respectively, and the two artificial bones had comparable compressive strength and Young's modulus, but the flexural strength of the nano-nacre artificial bone was lower than that of the micro-nacre artificial bone.</p><p><b>CONCLUSIONS</b>The nano-nacre artificial bone allows better biodegradability and possesses appropriate pore size, porosity and biomechanical properties for use as a promising material in bone tissue engineering.</p>

Prokaryotic expression and bioactivity of human platelet-derived growth factor B chain mature peptide / 南方医科大学学报

<p><b>OBJECTIVE</b>To express human platelet-derived growth factor (hPDGF) B chain mature peptide gene in a prokaryotic expression system and detect the bioactivity of the expressed protein.</p><p><b>METHODS</b>hPDGF B chain mature peptide gene was amplified and expressed in E. coli, and the recombinant protein, rhPDGF-BB, was purified and renatured in GSSG/GSS system. The bioactivity of rhPDGF-BB in vitro was evaluated with SD rat osteoblasts.</p><p><b>RESULTS</b>The full-length PDGF-B mature peptide gene was obtained and verified, and successfully expressed in E. coli. Bioactivity detection results showed that the expressed rhPDGF-BB obviously promoted the proliferation and DNA replication of SD rat osteoblasts in vitro (P<0.01).</p><p><b>CONCLUSION</b>he PDGF-B chain mature peptide cDNA has been successfully cloned and the PDGF-B precursor highly expressed in E. coli, and renatured rhPDGF-BB displays high bioactivity as shown by MTT assay and flow cytometry. This success provides the basis for production of functional PDGF-BB and facilitates further studies of its role in fracture healing and trauma reconstruction.</p>

Comparative study of dynamic fixation with rigid fixation in the management of degenerative lumbar spondylosis / 中华外科杂志

<p><b>OBJECTIVE</b>To compare the clinical effects of dynamic fixation and rigid fixation in the management of degenerative lumbar spondylosis.</p><p><b>METHODS</b>The hospitalized patients with degenerative lumbar spondylosis, including degenerative lumbar instability, lumbar spondylolisthesis and lumbar stenosis from January 2002 to December 2006 formed the subjects of our study. According to the inclusion criteria, 100 patients (male 58, female 42) were selected. The cases were divided into rigid fixation group (A) and dynamic fixation group (B), with 50 cases in each. The average age was (56 +/- 6) years old of group A, and (57 +/- 9) years old of group B. Standing plain radiography, computerized tomography (CT) or magnetic resonance imaging (MRI) were taken in all the cases. The observation index included incidence of adjacent segment degeneration (ASD), breakage of implant, fusion rate, lumbo-pelvic parameters and visual analogue scales (VAS) scores.</p><p><b>RESULTS</b>Six cases developed ASD in group A (12.0%), and 1 case in group B (2%). Implant breakage happened in 2 cases in group A (4.0%), while none in group B. There was 1 case of pseudo-articular formation in group A (2.0%), but none in group B. Lumbar lordosis (LL) was corrected with (14.2 +/- 2.2) degrees in group A, and (20.2 +/- 3.7) degrees in group B (P = 0.031). Sacral slope (SS) was corrected with (12.6 +/- 4.3) degrees in group A and (15.8 +/- 6. 5) degrees in group B (P = 0.052). Pelvic tilt (PT) was corrected with (8.3 +/- 2.7) degrees in group A and (4.5 +/- 2.2) degrees in group B (P = 0.014). Pelvic incidence was corrected with (2.0 +/- 0.1) degrees in group A and (0.9 +/- 0.1) degrees in group B (P = 0.008). The VAS score decreased significantly in both groups within the first 2 years after operation. But as time going, the patients with rigid fixation felt pain gradually, and the pain was more severe than in patients with dynamic fixation.</p><p><b>CONCLUSION</b>Dynamic fixation could prevent ASD and implant failure effectively.</p>