Aldosterone inhibits autophagy activation of mesangial cells and accelerates cell apoptosis under oxidative stress condition / 第二军医大学学报

Objective To investigate the effect of aldosterone on the activation of autophagy in mesangial cells. Methods Three classic techniques were used to detect the autophagy activity in mesangial cells with or without aldosterone treatment in this study. (1) Western blotting analysis was used to examine the expression of autophagy protein LC3, SQSTM1/P62 after human mesangial cell line (HMCL) was treated with different concentrations of aldosterone. (2) Confocal laser scanning microscope was used to observe the change of autophagy points after transforming eukaryotic expression vector GFP-LC3 into HMCL cells. (3) Transmission electron microscopy was used to observe the autophagic vacuoles of HMCL cells after treatment with aldosterone. Microscope and Western blotting analysis were used to observe the expression of apoptosis protein and poly(ADP-ribose) polymerase in mesangial cells under the conditions of oxidative stress (2.5×10-6mol/L H2O2 solution) and under the presence or absence of aldosterone. Results All the three methods confirmed that high physiological dose of aldosterone (10-7 mol/L) could inhibit mesangial cell autophagy activation: (1) The autophagy marker LC3 I converting to LC3 II had a decrease of approximately 40% after 10-7 mol/L aldosterone stimulation for 12 h. (2) The numbers of autophagy point of mesangial cells induced by Earle's balanced salt solution (EBSS) and rapamycin were also reduced by 60% and 47% upon aldosterone treatment, respectively. (3) Aldosterone treatment significantly reduced starvation and rapamycin-induced vacuole formation in mesangial cells examined by transmission electron microscopy. The mesangial cells treated by aldosterone had a significantly increased apoptosis rate than the control group under oxidative stress condition with hydrogen peroxide stimulation (2.5×10-6 mol/L, P<0.05). Conclusion High physiological concentration of aldosterone shows an inhibition against the basic autophagy activation of mesangial cells and accelerates cell apoptosis under conditions of oxidative stress.

Promoting lumbar spinal fusion by adenovirus-mediated bone morphogenetic protein-4 gene therapy / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To determine whether an adenoviral construct containing bone morphogenetic protein-4 (BMP-4) gene can be used for lumbar spinal fusion.</p><p><b>METHODS</b>Twelve New Zealand white rabbits were randomly divided into two groups, 8 in the experimental group and 4 in the control group. Recombinant, replication-defective type 5 adenovirus with the cytomegalovirus (CMV) promoter and BMP-4 gene (Ad-BMP-4) was used. Another adenovirus constructed with the CMV promoter and beta-galactosidase gene (Ad-beta-gal) was used as control. Using collagen sponge as a carrier, Ad-BMP-4 (2.9 multiply 10(8) pfu/ml ) was directly implanted on the surface of L(5)-L(6) lamina in the experimental group, while Ad-beta-gal was implanted simultaneously in the control group. X-ray was obtained at 3, 6, and 12 weeks postoperatively to observe new bone formation. When new bone formation was identified, CT scans and three-dimensional reconstruction were obtained. After that, the animals were killed and underwent histological inspection.</p><p><b>RESULTS</b>In 12 weeks after operation, new bone formation and fusion were observed on CT scans in the experimental group, without the evidence of ectopic calcification in the canal. Negative results were found in the control group. Histological analysis demonstrated endochondral bone formation at the operative site and fusion at early stage was testified.</p><p><b>CONCLUSIONS</b>In vivo gene therapy using Ad-BMP-4 for lumbar posterolateral spinal fusion is practicable and effective.</p>

Biomechanical and clinical study on screw hook fixation after direct repair of lumbar spondylolysis / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the biomechanical effect and clinical results of hook screw fixation after direct repair of lumbar spondylous defects in the pars interarticularis.</p><p><b>METHODS</b>L(2)-L(6) spines of 8 fresh-frozen and thawed calf cadavers were used for mechanical testing. Bilateral spondylous defects were created in the L(4)vertebra. The intervertebral rotation ranges between L(4) and L(5) were scanned and computerized in various states of motion, such as flexion/extension, lateral bending and torsional loadings applied on the intact spine and the spondylous spine when the spondylous spine was fixed with modified Scott's fixation, hook screw fixation and Buck's fixation sequentially and respectively. Between July 2002 and February 2004, 14 young male patients (aged 15-31 years) suffering from symptomatic lumbar spondylolysis were treated with TSRH hook screw fixation after direct repair of the defects. MacNab criteria were used to assess their pre-and post-operative status.</p><p><b>RESULTS</b>Each fixation technique could significantly increase the intervertebral rotational stiffness and made the stiffness return to nearly the intact level. Hook screw technique provided more rotational stability than the others. Hook screw and Buck's techniques provided more flexion/extension stability than modified Scott's technique. Neither complication nor instrumental failure was observed in this study. The mean follow-up period was 21 months. All the patients except one acquired union during the follow-up period. Thirteen patients had a "good" or "excellent" result according to MacNab criteria.</p><p><b>CONCLUSIONS</b>Hook screw fixation shows biomechanical advantages and is safe and effective for young patients with lumbar spondylolysis.</p>