Our previous work has indicated that enzymatic resolution of glycidyl butyrate are strongly affected by many factors, including concentration of substrate, amount of lipase, the temperature, pH, shaking speed and reaction time. In this study, Plackett-Burman design was undertaken to evaluate the effects of the six factors. By regression analysis, concentration of substrate, amount of lipase and the temperature were found to be important for enzymatic resolution of glycidyl butyrate. In the second phase of the optimization process, a response surfacemethodology (RSM) was used to optimize the above critical factors, and to find out the optimal concentration levels and the relationships between these factors. By solving the quadratic regression model equation using appropriate statistic methods, the optimal parameter of the variables were determined as: 0.499 mol/L glycidyl butyrate, 30.23 mg/g lipase and 29.68 degrees C. In the optimum condition, the value of enantiomeric excess(ee%) was 93.28%. Compared to 84.65% which was the maximum ee% under the non-optimized condition, this study has a significant advancement. The experimental data under various conditions have validated the theoretical values.
Butyrates ; chemistry ; Catalysis ; Enzyme Activation ; Epoxy Compounds ; chemistry ; Lipase ; metabolism ; Molecular Conformation ; Propanols ; chemistry ; Regression Analysis ; Stereoisomerism ; Substrate Specificity ; Temperature

This paper elaborated and analyzed the characteristics, clinical application and limitations of risk assessment tools for venous thromboembolism at home and abroad so as to provide a reference for improving and selecting assessment tools, and an early risk warning for patients with the risk of venous thromboembolism to carry out effective individualized prevention.

Objective:To observe the impacts of different postures on the hemodynamics of lower extremity vein.Methods:In this single center non-randomized controlled study in 15 healthy female volunteers, the hemodynamic changes in the common femoral vein were detected by color Doppler ultrasound at 10 different postures: supine position, slope positions with bed end elevated at 15°, 30° and 45°, trapezoidal positions with bed end elevated at 15°, 30° and 45°, and positions with bed head elevated at 30°, 45° and 60°.Results:Different postures resulted in significant differences in the velocity of blood flow in the common femoral vein ( P<0.05), with slope position at 45°> slope position at 30°> slope position at 15° = trapezoidal position at 30°> trapezoidal position at 15° = trapezoidal position at 45°> supine position> position with bed head elevated at 30°> position with bed head elevated at 45° = position with bed head elevated at 60°. Conclusions:In the postures observed in this study, the slope position with bed end elevated at 45° can promote the most effectively the blood reflux in the lower extremity vein, the trapezoidal positions with bed end elevated may not facilitate the distal blood reflux in the lower extremity vein, and positions with bed head elevated may hinder the blood reflux in the lower extremity vein.

Objective:To investigate the epidemiological characteristics of lower extremity deep vein thrombosis (DVT) in patients with femoral fracture.Methods:Retrospectively analyzed were the data of 2,571 patients with femoral fracture who had been treated at the Third Hospital of Hebei Medical University from January 2019 to December 2019. There were 1,079 males and 1,492 females, aged from 14 to 96 years (average, 67.1 years). There were 1,158 femoral neck fractures, 951 femoral intertrochanteric fractures, 309 femoral shaft fractures, and 153 femoral condylar fractures. 2,414 patients were treated surgically while 157 patients non-surgically. Color Doppler ultrasonography of both lower extremities was performed to determine the occurrence of DVT before operation and every week after operation for patients undergoing surgical treatment, and within 48 hours after admission and every week during hospitalization for those undergoing non-surgical treatment. The incidence and location of DVT were recorded for different femoral fractures.Results:The incidence of DVT in this cohort was 35.5%(913/2,517), that of proximal DVT 5.3%(135/2,571), and that of distal DVT 30.3% (778/2,571). In patients with femoral neck fracture, femoral intertrochanteric fracture, femoral shaft fracture and femoral condylar fracture, the incidence of DVT was respectively 28.8% (334/1,158), 44.7% (425/951), 30.7% (95/309) and 38.6% (59/153), the incidence of proximal DVT was respectively 2.7% (31/1,158), 5.6%(53/951), 9.7% (30/309) and 13.7% (21/153), and the incidence of distal DVT was respectively 26.2% (303/1,158), 39.1% (372/951), 21.0% (65/309) and 24.8%(38/153). The incidence of DVT in the femoral vein and above, popliteal vein, tibiofibular vein and intermuscular vein in this cohort was respectively 2.3%(60/2,571), 2.9%(75/2,571), 6.4%(165/2,571) and 23.8%(613/2,571).Conclusions:The incidence of DVT may be high in patients with femoral fracture, and the proximal DVT with a high risk of pulmonary embolism may occur more in patients with femoral condylar fracture.