Hepatitis B e antigen perturbs the LPS-stimulated production of inflammatory cytokines by mononuclear-derived dendritic cells / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate whether hepatitis B e antigen (HBeAg) can modulate the ability of dendritic cells (DCs) to produce inflammatory cytokines (IL-12/IL-6) upon stimulation in vitro.</p><p><b>METHODS</b>Purified adherent mononuclear cells isolated by Ficoll-hypaque density gradient centrifugation were cultured in complete medium containing granulocyte macrophage colony-stimulating factor plus interleukin (IL)-4 to generate immature (i)DCs. Microscopic analysis and flow cytometry were performed to define the phenotypic characteristics of the iDCs. Then, different concentrations (1, 2 and 5 mug/ml) of HBeAg were added to the culture medium and for 24 hrs of incubation. To induce iDCs' maturation, the various groups of cells were incubated for 24 hrs in differentiation culture with lipopolysaccharide (LPS). Effects on secreted inflammatory cytokines were determined by enzyme-linked immunosorbent assay of the cells' supernatants.</p><p><b>RESULTS</b>All concentrations of HBeAg led to significant reductions in IL-6 (all P less than 0.05). Similar significant reduction trends were seen for IL-12 at the HBeAg concentrations of 2 and 5 mug/ml (both P less than 0.05), but not at the 1 mug/ml concentration.</p><p><b>CONCLUSION</b>HBeAg may suppress the production of cytokines from DCs; this mechanism may contribute to the immune escape of HBV that supports persistent infection.</p>

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.

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

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>