[Effects of low-frequency pulsed wave ultrasound on the shear properties of the interface of vancomycin-loaded acrylic bone cement-stem].

Objective: To investigate the effects of low-frequency pulsed wave ultrasound on the shear properties of interface of the vancomycin -loaded acrylic bone cement-stem. Methods: The interfaces of 1% vancomycin-loaded acrylic bone cement-stem specimences were successfully manufactured and randomly divided into three groups: the control group, 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) ultrasound group, each group consisted of eight samples.Two ultrasound groups were exposed to a local ultrasonic field for 7 d, then immersed in PBS for 23 d, and the control groups were immersed in PBS for 30 d. After curing in air for 24 h, the shear strength of the stem-cement interface was determined by push-out test.The specimens were then photographed using SEM and analysed using Image-Pro Plus 6.0 to determine the porosity at the stem-cement interface. Results: The mean shear strength of stem-cement interface additionally decreased by 9% (P>0.05) and 17% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, but no significant difference was found between the two ultrasound groups.The porosity at the stem-cement interface additionally increased by 44% (P>0.05) and 110% (P<0.05) in 450 mW/cm(2) ultrasound group and 1 200 mW/cm(2) group respectively comparing with the control group, furthermore.The porosity in 1 200 mW/cm(2) ultrasound group increased by 46% (P<0.05) comparing with the 450 mW/cm(2) group. There are much more fluid penetration along the stem-cement interface in ultrasound group . Conclusion: Low-frequency pulsed wave ultrasound signifiantly enhanced porosity and fluid penetration interface, and reduced the interface shear strength and initial stability.

Hypomethylation of interleukin-6 (IL-6) gene increases the risk of essential hypertension: a matched case-control study.

Essential hypertension (EH) is a chronic disease with clear epigenetic component. Inflammation and endothelial dysfunction have a great role in the development of persistent blood pressure elevation. The aim of this study was to explore an association between EH and DNA methylation in pro-inflammation cytokine gene interleukin-6 (IL-6) during the inflammatory process. We performed methylation analysis of peripheral blood DNA using bisulphite pyrosequencing technology between 96 EH patients and 96 age- and gender-matched healthy controls. The present results showed that three cytosine-phosphate-guanine (CpG) sites of IL-6 promoter CpG island had different lower methylation in EH group compared with controls, but only CpG2 (58.43±7.53 versus 62.34±9.65, P=0.004) and CpG3 (51.52±6.18 versus 57.45±8.29, P<0.001) had statistical difference. Logistic regression analysis found CpG3 hypomethylation was a risk factor of EH (odds ratio=1.111, adjusted P=0.004). In addition, we found hypermethylation of CpG1 (64.84±7.06 versus 61.84±8.61) and CpG2 (62.04±7.40 versus 59.30±9.57) in male compared with female. In male, we found hypomethylation of CpG2 (60.41±7.74 versus 64.28±6.36) and CpG3 (53.70±8.62 versus 57.78±7.87) of smoker versus non-smoker and hypomethylation of CpG2 (60.89±7.32 versus 64.70±7.03) and CpG3 (53.23±7.99 versus 60.48±7.58) of drinker versus non-drinker. Furthermore, the CpG2 and CpG3 had a negative correlation with systolic blood pressure and diastolic blood pressure (P<0.05). Receiver operating characteristic curve analysis showed that CpG2 (area under curve: 0.638, P=0.001) and CpG3 (area under curve: 0.704, P<0.001) had a diagnostic value to predict the risk of EH. In summary, our study revealed hypomethylation of IL-6 was correlated with the risk of EH in the population assessed and we found the differences of IL-6 promoter methylation in gender, smoking and drinking.