BACKGROUND: Leptin is a kind of polypeptide hormone secreted by fatty tissue, previous studies have shown that leptin plays a certain role in the formation of atherosclerosis.OBJECTIVE: To investigate the effects of leptin on the expression of tumor necrosis factor-alpha (TNF-α) in RAW264.7 cells, and investigate the possible mechanism from the angle of the change of nuclear factor-κB (NF-κB) activity.DESIGN: A controlled observational experiment.SETTING: Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: The experiments were carried out in the Department of Biochemistry and Molecular Biology, Tongji Medical College, and the Department of General Surgery, Union Hospital affiliated to Huazhong University of Science and Technology between April 2005 and February 2006.The cultured RAW264.7 cells were divided into leptin treated groups treated with different concentration (12.5, 25, 50, 100 μg/L), I kappa B kinase inhibitor group and blank control group. Each group had 3 sub-wells,and the experiments were repeated for 3 times.METHODS: Mouse macrophage RAW264.7 cells were incubated into a 6-well plate at the density of 109 cells L-1, cultured in RPMI-1640 culture medium containing bovine serum of 0.1 in volume fraction. When the cells grew to 80%, serum-free culture medium Opti-MEM was changed to culture for another 24 hours, and then the cells were divided into leptin groups treated with different concentration (12.5, 25, 50, 100 μg/L), I kappa B kinase inhibitor group and blank control group. After the cells were incubated with leptin for 4 hours, the expression of TNF-α mRNA expression in RAW264.7 cells was detected with reverse transcription-polymerase chain reaction (RT-PCR). After the RAW264.7 cells were incubated with leptin for 1, 3, 6 and 9 hours, the expression of TNF-c protein expression was detected with double antibody sandwich enzyme-linked immunosorbent assay (ELISA). After the RAW264.7 cells were incubated with leptin for different times, the activity of NF-κB was detected analyzed with electrophoretic mobility shift assay. Another, the RAW264.7 cells were treated with or without 50 μmol/L leptin and/or 100 μmol/L PS1145 (I kappa B kinase specific inhibitor)divided into four groups: blank control group, I kappa B kinase specific inhibitor PS1145 (10 μmol/L) treated group, leptin (50 μmol/L) treated group, leptin (50 μmol/L) + PS1145 (10 μmol/L) group. Aftere incubated for 6 hours, the activity of NF-κB and expression TNF-α mRNA were detected respectively.MAIN OUTCOME MEASURES: ① Effect of leptin of different concentration on the expression of TNF-α mRNA and protein in RAW264.7cells; ② Effect of leptin of different concentration on the activity of NF-κB in RAW264.7 cells; ③ Influence of inhibition I kappa B kinase activity inhibition on expression of TNF-a induced by leptin in RAW264.7cells.RESULTS: ① After the RAW264.7 cells were treated with leptin of different concentration, the TNF-α mRNA level was elevated in a dose-dependent manner, and it reached the peak value emerged in the 50 μg/L leptin treated group. ② The expression of TNF-α protein increased in dose-dependent and time-dependent manners, and it reached the peak val ue at 6 hours in the 50 μg/L leptin treated group. ③ The activity of NF-κB was also positively correlated with the leptin concentration, and it was the highest value at 6 hours treated with 50 μg/L leptin (P ＜ 0.05). ④ I kappa B kinase activity inhibition only partially suppressed the leptin induced elevation of TNF-α expression induced by leptin.CONCLUSION: Leptin can increase the expression and secretion of TNF-α in RAW264.7 cells directly in both dose-dependent and time-dependent manners, and the mechanism may be correlated with the activated NF-κB induced by leptin. It may be one of the mechanisms of atherosclerosis induced by leptin.

AIM: To observe skeletal muscle damage of mdx mice after overload exercise, and protection to muscle damage induced by exercise due to myoblast transplantation (MTT). METHODS: Muscle samples of C 57 mice were minced and digested with trypsin, and myoblasts were cultured ex vivo , purified and detected by immunohistochemistry stains. The myoblasts were injected into muscle of left limb of mdx mice, whereas the right limb was injected with DMEM liquid as control. Mice were submitted to exercise for 3 days starting 1 month after MTT, and then Evans blue was injected intravenously through the tail vein. The muscle cryostat sections of mdx mice were made, and then detected the immunofluorescence of dystrophin. Under a fluorescence microscope, the number of fiber stained with Evans blue and dystrophin was counted, analyzed quantitatively with image software. RESULTS: Under a fluorescence microscope, only 10 37%?2 87% muscle fibers in the myoblast grafted muscles were stained with Evans blue. In contrast, 26 82%?14 85% muscle fibers in right control muscles were stained. Significant differences between these two groups were showed ( P

Hot-melt extrusion was applied to prepare mesoporous silica/ethylcellulose mini-matrix for sustained release, and fenofibrate was used as a model drug, ethylcellulose and xanthan gum were chosen as sustained-release agent and releasing moderator, respectively. This novel matrix obtained the controlled release ability by combining mesoporous silica drug delivery system and hot-melt extrusion technology. And mesoporous silica particle (SBA-15) was chosen as drug carrier to increase the dissolution rate of fenofibrate in this martix. Scanning electron microscope, transmission electron microscope, small angle X-ray powder diffraction and N2 adsorption-desorption were introduced to determine the particle morphology, particle size and pore structure of the synthesized SBA-15. The results showed that SBA-15 had a very high Brunauer-Emmett-Teller specific surface area, a narrow pore size distribution, large pore volume and a ordered two-dimensional hexagonal structure of p6mm symmetry. Differential scanning calorimetry and X-ray powder diffraction results demonstrated that fenofibrate dispersed in an amorphous state inside the pores of the mesoporous silica which contributed to the improvement in the dissolution rate. The drug release of mini-matrices was influenced by ethylcellulose viscosity grades and xanthan gum concentration, which increased with the increasing of xanthan gum concentration and decreasing of ethylcellulose viscosity. Mini-matrix containing 22% xanthan gum exhibited a good sustained release performance, and the drug release behavior followed the first-order kinetics.