A Highly Active Chondroitin Sulfate Lyase ABC for Enzymatic Depolymerization of Chondroitin Sulfate.

Enzymatic preparation of low-molecular-weight chondroitin sulfate (LMWCS) has received increasing attention. In this work, a chondroitin sulfate lyase ABC (Chon-ABC) was successfully cloned, expressed, and characterized. The Km and Vmax of the Chon-ABC were 0.54 mM and 541.3 U mg-1, respectively. The maximal activity was assayed as 500.4 U mg-1 at 37 °C in pH 8.0 phosphate buffer saline. The half-lives of the Chon-ABC were 133 d and 127 min at 4 °C and 37 °C, respectively. Enzymatic preparation of LMWCS was performed at room temperature for 30 min. The changes between the substrate and product were analyzed with mass spectrometry (MS), high-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). Overall, the Chon-ABC from Bacteroides thetaiotaomicron is competitive in large-scale enzymatic preparation of LMWCS for its high activity, stability, and substrate specificity.

Pressure-controlled versus volume-controlled ventilation during one-lung ventilation for video-assisted thoracoscopic lobectomy.

BACKGROUND: It is controversial as to which ventilation mode is better during one-lung ventilation (OLV). This study was designed to figure out whether there was any difference between volume controlled ventilation (VCV) and pressure controlled ventilation (PCV) on oxygenation and postoperative complications under the condition of protective ventilation (PV). METHODS: Sixty-five patients undergoing video-assisted thoracoscopic lobectomy were randomized into two groups. Patients in group V received VCV mode during OLV while patients in group P received PCV. The tidal volume (VT) in both groups was 6 mL per predicted body weight (PBW). Positive end-expiratory pressure (PEEP) was set at the level of 5 cmH2O in both groups. Arterial gas analysis were performed preoperatively with room air (T0), at 15 mins (T1) and 1 h (T2) after OLV, at the end of OLV (T3), 30 min after PACU admission (T4), 24 h after surgery (post-operative day 1, POD1) and 48 h after surgery (post-operative day 2, POD2). Peak inspiratory airway pressure (Ppeak) and plateau airway pressure (Pplat) were recorded at T1, T2 and T3. The perioperative complications were also recorded. RESULT: Sixty-four patients completed this study. Ppeak in group V was significantly higher than that in group P (T1 22.3±2.9 vs. 18.7±2.1 cmH2O; T2 22.2±2.8 vs. 18.7±2.6 cmH2O). There were no differences with Pplat and intraoperative oxygenation index (T1 203.3±109.7 vs. 198.1±93.4; T2 216.8±79.1 vs. 232.1±101.4). The postoperative oxygenation index (T4 525.0±160.9 vs. 520.7±127.1, post-operative day 1 (POD1) 452.1±161.3 vs. 446.1±109.1; post-operative day 2 (POD2) 403.8±93.4 vs. 396.7±92.8) and postoperative complications were also comparable between these two groups. CONCLUSIONS: When they were utilized during OLV, PCV and VCV had the same performance on the intraoperative oxygenation and postoperative complications under the condition of PV.

Using concanavalinA as a spacer for immobilization of E. coli onto magnetic nanoparticles.

ConcanavalinA (conA) is a protein extracted from the concanavalin, which has specific recognition through mannose components on bacterial cell surfaces. A magnetic nanocarrier with the structure of a dopamine functionalized magnetic nanoparticles was grafted with conA, and was used for immobilization of recombinant Escherichia coli harboring glycerol dehydrogenase with the specific recognition between glycoconjugates and glycoprotein. The effect of various factors on the immobilization including temperature, pH, cell concentration and immobilization time were investigated. The highest immobilization yield of 91% was obtained under the conditions: enzyme/support 1.28mg/mg, pH 8.0, immobilization time 2h and temperature 4°C. The obtained immobilized cell was characterized and exhibited higher thermal stability compared with the free cell. After ten cycles, the immobilized cell remained 62% initial activity. These results indicate that the cell immobilized onto conA-grafted nanoparticles by specific recognition of glycoconjugates and glycoprotein is a potential method for preparation of stable cell, and the immobilized cell showed perspective applications in the biocatalysis and biosensors.

Effect of parecoxib combined with thoracic epidural analgesia on pain after thoracotomy.

BACKGROUND: Thoracotomy results in severe postoperative pain potentially leading to chronic pain. We investigated the potential benefits of intravenous parecoxib on postoperative analgesia combined with thoracic epidural analgesia (TEA). METHODS: Eighty-six patients undergoing thoracic surgery were randomized into two groups. Patient-controlled epidural analgesia (PCEA) was used until chest tubes were removed. Patients received parecoxib (group P) or placebo (group C) intravenously just 0.5 h before the operation and every 12 h after operation for 3 days. The intensity of pain was measured by using a visual analogue scale (VAS) and recorded at 2, 4, 8, 24, 48, 72 h after operation. The valid number of PCA, the side effects and the overall satisfaction to analgesic therapy in 72 h were recorded. Venous blood samples were taken before operation, the 1(st) and 3(rd) day after operation for plasma cortisol, adrenocorticotropic hormone (ACTH), interleukin-6 and tumor necrosis factor-α level. The occurrence of residual pain was recorded using telephone questionnaire 2 and 12 months after surgery. RESULTS: Postoperative pain scores at rest and on coughing were significantly lower with the less valid count of PCA and greater patient satisfaction in group P (P<0.01). Adverse effect and the days fit for discharge were comparable between two groups. The cortisol levels in placebo group were higher than parecoxib group at T2. The level of ACTH both decreased in two groups after operation but it was significantly lower in group P than that in group C. There were no changes in plasma IL-6 and TNF-α levels before and after analgesia at T1 and T2 (P>0.05). The occurrence of residual pain were 25% and 51.2% separately in group P and C 3 months postoperatively (P<0.05). CONCLUSIONS: Intravenous parecoxib in multimodal analgesia improves postoperative analgesia provided by TEA, relieves stress response after thoracotomy, and may restrain the development of chronic pain.

Covalent Immobilization of Penicillin G Acylase onto Fe3O4@Chitosan Magnetic Nanoparticles.

Penicillin G acylase (PGA) was immobilized on magnetic Fe3O4@chitosan nanoparticles through the Schiff base reaction. The immobilization conditions were optimized as follows: enzyme/support 8.8 mg/g, pH 6.0, time 40 min, and temperature 25°C. Under these conditions, a high immobilization efficiency of 75% and a protein loading of 6.2 mg/g-support were obtained. Broader working pH and higher thermostability were achieved by the immobilization. In addition, the immobilized PGA retained 75% initial activity after ten cycles. Kinetic parameters Vmax and Km of the free and immobilized PGAs were determined as 0.91 mmol/min and 0.53 mmol/min, and 0.68 mM and 1.19 mM, respectively. Synthesis of amoxicillin with the immobilized PGA was carried out in 40% ethylene glycol at 25°C and a conversion of 72% was obtained. These results showed that the immobilization of PGA onto magnetic chitosan nanoparticles is an efficient and simple way for preparation of stable PGA.