Purification and subunit structure studies of human placental threonyl-tRNA synthetase

Human threonyl-tRNA synthetase has been purified from full-term placenta over 5000-fold with a 13% overall yield by a combination of affinity chromatographic methods and conventional procedures. The product was apparently homogeneous by the criterion of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme catalyzed the esterification of ? 3500 nmol L-threonine to tRNA per min per mg of protein at 37°, corresponding to a molecular activity of ? 700/min. The apparent molecular weight of the native enzyme ranged from 210 000 to 220 000 by gel-filtration on Sephadex G-200, and was either ? 110 000 or 228 000 by sucrose gradient centrifugation for different preparations. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated a single band of molecular weight 85 000 or 115 000 for different preparations. These results suggest that human placental threonyl-tRNA synthetase has a subunit structure of the type α₂ with a subunit molecular weight of about 100 000. However, some other molecular forms with lower specific activity were also found to exist under certain conditions.     

双稠吡咯啶生物碱的研究 Ⅰ.森林千里光的生物碱

从浙江天目山采集的森林千里光(Senecio nemorensis)中分得二个双稠吡咯啶类型的生物碱,其中之一熔点为55—57℃,分子式为C₁₃H₂₁O₃N。另一熔点为42—43℃,分子式为C₁₈H₂₇O₅N。由其理化常数及酒石酸盐、苦味酸盐、水解产物等结果,与文献上记载的大叶千里光中所得的macrophylline及从瓶草千里光中所得的sarracine比较,证明前者与macrophylline相同,而后者与sarracine相同。     

负压封闭引流术治疗胫腓骨开放性骨折合并严重软组织损伤

目的：探讨应用负压封闭引流技术治疗胫腓骨开放性骨折合并严重软组织损伤的疗效。方法：对14例胫腓骨开放性骨折合并严重软组织损伤患者,进行清创及骨折固定后,应用持续负压封闭引流,6～8 d后拆除敷料。必要时再次行负压封闭引流,二期植皮。结果：14例患者中5例皮肤回植大部分成活,7例患者使用负压封闭引流术治疗后行二期植皮全部...