RESUMO
Objective:To compare the efficacy and safety of ultrasound-guided percutaneous translumial septal myocardial ablation in dogs using laser and radiofrequency.Methods:Twelve healthy adult Beagle dogs (males or females) were randomly divided into two groups, namely, group laser and group radiofrequency (6 dogs each group). Under ultrasound guidance, laser fiber or radiofrequency ablation needle was respectively inserted into the basal and middle segments of the interventricular septa via the percutaneous transapical approach to perform ablation. The Beagle dogs received radiologic examination, laboratory tests and pathological detection before ablation, immediately after ablation, at 1 week after ablation, and at 1 month after ablation, respectively. The efficacy and safety of the two ablation procedures were compared.Results:All dogs survived after ablation. The peak gradient of LVOT decreased immediately after ablation using either laser or radiofrequency ( P<0.05), but it increased at 1 week after ablation than before ( P<0.05). At 1 month after ablation, no significant differences were found in the peak gradient of LVOT compared with that before surgery ( P<0.05). The interventricular septum thickness was increased immediately after ablation using either laser or radiofrequency than before ( P<0.05), but it decreased at 1 week and at 1 month after surgery than before ( P<0.05). The ablation zone using radiofrequency was slightly larger than that of using laser[(372.50±69.06)mm 3 vs (116.65±20.15)mm 3, P<0.001], and the surgical time of the former was significantly shorter than that of using laser [(56.00±3.22)s vs (260.00±65.39)s, P<0.05)]. Conclusions:Ultrasound-guided percutaneous translumial septal myocardial ablation is feasible, safe and effective using either laser or radiofrequency. Comparatively speaking, radiofrequency ablation is more simple and convenient.
RESUMO
The novel and degradable xylan citrate was prepared by the environmental-friendly semi-dry oven method. Xylan reacted with citric acid (CA) to yield xylan citrate at high temperature. The influence of the different weight ratios of CA and xylan on the product yield, the carboxyl group content and degree of esterification were comparatively discussed. The results showed that there were higher carboxyl group content and degree of esterification in modified xylan than native xylan. The product yield of 128.2%, the carboxyl group content of 1174.3 meq/100 g and degree of esterification of 33.1% were achieved at the CA/xylan weight ratio of 2.4 in the absence of catalyst. Furthermore, the adsorption capacity of xylan after modification was improved greatly. These materials with better properties can enhance their water affinity, and improve their adsorption of copper ions and methyl orange in aqueous solution due to carboxyl groups.
