The whole-cell immobilization of D-hydantoinase-engineered Escherichia coli for D-CpHPG biosynthesis

Background: D-Hydroxyphenylglycine is considered to be an important chiral molecular building-block of antibiotic reagents such as pesticides, and β-lactam antibiotics. The process of its production is catalyzed by D-hydantoinase and D-carbamoylase in a two-step enzyme reaction. How to enhance the catalytic potential of the two enzymes is valuable for industrial application. In this investigation, an Escherichia coli strain genetically engineered with D-hydantoinase was immobilized by calcium alginate with certain adjuncts to evaluate the optimal condition for the biosynthesis of D-carbamoyl-p-hydroxyphenylglycine (D-CpHPG), the compound further be converted to D-hydroxyphenylglycine (D-HPG) by carbamoylase. Results: The optimal medium to produce D-CpHPG by whole-cell immobilization was a modified Luria-Bertani (LB) added with 3.0% (W/V) alginate, 1.5% (W/V) diatomite, 0.05% (W/V) CaCl2 and 1.00 mM MnCl2.The optimized diameter of immobilized beads for the whole-cell biosynthesis here was 2.60 mm. The maximized production rates of D-CpHPG were up to 76%, and the immobilized beads could be reused for 12 batches. Conclusions: This investigation not only provides an effective procedure for biological production of D-CpHPG, but gives an insight into the whole-cell immobilization technology.

Optimal clinical dose of rocuronium bromide for laryngeal mask airway insertion during sevoflurane anesthesia in children / 대한마취과학회지

BACKGROUND: The median effective dose, ED(50), of rocuronium bromide for inserting the laryngeal mask airway (LMA) in children was not known. The purpose of this study was to determine the clinical ED(50) (cED(50): median value of rocuronium dose of 6 set of crossing success and failure by Dixon's up-and-down method) of rocuronium to insert a LMA in pediatric patients. METHODS: Children aged 2 to 12 years (n = 21) and scheduled for urologic, orthopedic, plastic or ophthalmic surgery lasting less than 2 hr under general anesthesia were enrolled in this study. After applying a standard cardiorespiratory monitor, all patients received thiopental sodium 5 mg/kg for induction of anesthesia. Insertion of LMA was attempted 90 seconds after administration of rocuronium and manual ventilation with 8 vol% of sevoflurane. We recorded the movement of patients, blood pressure and heart rate. The initial dose of rocuronium was 0.3 mg/kg, and in accordance with Dixon's up-and-down method, the rocuronium concentration for consecutive patients in each patient was varied with increments or decrements of 0.05 mg/kg based on the result of previous patient. RESULTS: The cED(50) of rocuronium required to insert a LMA was 0.09 mg/kg with 8 vol% sevoflurane. With isotonic regression, cED95 of rocuronium was 0.13 mg/kg (95% confidence intervals 0.096-0.14 mg/kg). CONCLUSIONS: This study demonstrated that the cED(50) and cED(95) of rocuronium were 0.09 mg/kg and 0.13 mg/kg in children respectively. It provides satisfactory conditions for LMA insertion in anesthetized children and decreases the excessive hemodynamic change.