The expression of mammalian target of rapamycin and its substrates in autogenous vein graft in rats / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the expression of mammalian target of rapamycin (mTOR) and its substrates including p70s6k and 4E-BP1 in autogenous vein graft.</p><p><b>METHODS</b>Autogenous vein graft model was established in 64 Wistar rats by transplanting the right common jugular vein to infrarenal abdominal aorta. Vein graft samples were harvested 6 hours, 1 day, 3 days, 1 week, 2 weeks, 4 weeks, 6 weeks and 8 weeks after surgery. The mRNA expression of mTOR, p70s6k and 4E-BP1 were measured by RT-PCR and in situ hybridization. Western blot and immunohistochemistry methods also were used to detect the protein expression of mTOR, p70s6k and 4E-BP1. Proliferating cell nuclear antigen (PCNA) was also detected at the same time.</p><p><b>RESULTS</b>The mRNA expression of mTOR and p70s6k increased soon after vein graft transplanting, rose quickly and reached the peak 3 days to 2 weeks after surgery, which recovered 6 to 8 weeks after surgery. The expression of 4E-BP1 mRNA decreased soon after surgery and reached the lowest at 1 week, then rose to the peak 4 to 6 weeks after transplantation. Protein expression of mTOR and p70s6k reached the peak 2 to 4 weeks and recovered to normal level 8 weeks after surgery, but the expression of 4E-BP1 decreased to the lowest during 1 to 2 weeks and reached the peak 4 to 6 weeks after transplanting. The positive cells mostly located in vascular smooth muscle cell (VSMC) just like PCNA.</p><p><b>CONCLUSIONS</b>The expression of mTOR and its substrates were activated in vein graft soon after transplantation, which means that mTOR and its substrates might become new targets for the prevention and therapy of stenosis or obliteration after vein graft transplanting.</p>

Cyclic fatigue of Vita mark II machinable ceramics under Hertzian's contact / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the cyclic fatigue modes of Vita mark II machinable ceramics under Hertzian's contact.</p><p><b>METHODS</b>Hertzian's contact technique (WC spheres r = 3.18 mm) was used to investigate the cyclic fatigue of Vita mark II machinable ceramic. All specimens were fatigued by cyclic loading in moist environment, furthermore, surviving strength was examined by three point test and morphology damage observation.</p><p><b>RESULTS</b>In homogeneous Vita mark II machinable ceramics, two fatigue damage modes existed after cyclic loading with spheres under moist environment, including conventional tensile-driven cone cracking (brittle mode) and shear-driven microdamage accumulation (quasi-plastic mode). The latter generated radial cracks and deeply penetrating secondary cone crack. Initial strength degradation were caused by the cone cracks, subsequent and much more deleterious loss was caused by radial cracks.</p><p><b>CONCLUSION</b>Cyclic fatigue modes of Vita mark II machinable ceramics includes brittle and quasi-plastic mode.</p>

The expression and significance of hypoxia-inducible factor-1 alpha and related genes in abdominal aorta aneurysm / 中华外科杂志

<p><b>OBJECTIVE</b>To study the expression of hypoxia-inducible factor (HIF)-1alpha and related genes in abdominal aorta aneurysm (AAA) and explore the underlying pathogenesis.</p><p><b>METHODS</b>Twenty-two AAA specimens were collected and 5 normal abdominal aorta tissue were used as control. Northern blot, western blot and immunohistochemistry were used to evaluated the expression of HIF-1alpha mRNA and protein product. Western blot and immunohistochemistry method were also used to determine the expression of vascular endothelial growth factor (VEGF) and caspase-3. Microvessel density (MVD) was studied by immunohistochemistry stain of CD34.</p><p><b>RESULTS</b>The expression of HIF-1alpha mRNA and protein product were significantly higher in AAA than that in normal abdominal aorta (P < 0.01). The expression of VEGF and caspase-3 were also higher in AAA and both had a significantly positive relationship with HIF-1alpha expression (P < 0.01). Most of the positive cells located in VSMC and adventitia of AAA. The MVD counts were higher in AAA.</p><p><b>CONCLUSION</b>HIF-1alpha may have an important role the development of AAA, which maybe obtained by regulating the expression of VEGF or caspase-3.</p>