Alpha-glycerophosphate oxidase (α-GPO) from Enterococcus casseliflavus was successfully isolated and purified by using polyethylene glycol (PEG)/(NH4)2SO4 aqueous two-phase system (ATPS). The results showed that the chosen PEG/(NH4)2SO4 ATPS could be affected by PEG molecular weight, pH, concentration of PEG and (NH4)2SO4, and inorganic salt as well as additional amount of crude enzyme. After evaluating these influencing factors, the final optimum purification strategy was formed by 16.5% (m/m) PEG2000, 13.2% (m/m) (NH4)2SO4, pH 7.5 and 30% (m/m) additive crude enzyme, respectively. The NaCl was a negative influencing factor which would lead to lower purification fold and activity recovery. These conditions eventually resulted in the activity recovery of 89% (m/m), distribution coefficient of 1.2 and purification fold of 7.0.
ObjectiveTo evaluate the efficacy of bipolar radiofrequency ablation procedure for atrial fibrillation (AF) during the open-heart surgery. MethodsWe retrospectively analyzed the clinical data of 137 heart disease patients combined with AF (21 patients combined with left atrial thrombus) who underwent one-stage operation of open-heart surgery and bipolar radiofrequency ablation from May 2009 to June 2014. There were 61 males and 76 females at age of 35-73(48.3±11.6)years. The patients received amiodarone treatment for 6 months after surgery and regular follow-up. The sinus rhythm conversion rate, cardiac function before and after operation, survival rate after operation, the incidence of thromboembolism and other complications were recorded. ResultsThe average cardiopulmonary bypass time during operation was 122±38 min, the average aortic crossclamp time was 78±22 min, and the average radiofrequency ablation time was 20±4 min. The atrial fibrillation was successfully ablated in 130 patients on the same day of surgery with conversion rate of 94.9%. The atrial fibrillation was converted to sinus rhythm in 114 patients, and converted to junctional cardiac arrhythmia in 16 patients. Two patients died during the perioperative period with death rate of 1.5% in hospital. The conversion rate was 81.5% (110/135), 88.1% (111/126), 83.1% (74/89), and 83.0% (39/47) respectively at one month, six months, one year, and two years after surgery, respectively. The survival rate was 96.6% (86/89) and 93.6% (44/47) at one year and two years after surgery. No thromboembolism occurred during the long-term follow-up period. ConclusionBipolar radiofrequency ablation procedure selectively performed during open-heart surgery can cure atrial fibrillation, only increases cardiopulmonary bypass and aortic crossclamp time slightly. The short- and mid-term efficacy is satisfactory with high conversion rate of sinus rhythm. The long-term effect still needs further observation.