桔梗皂苷对慢性支气管炎小鼠肺细胞中的IL-1β和TNF-α表达的影响

探讨炎性细胞因子在慢性支气管炎小鼠肺细胞中的表达及桔梗皂苷(kikyosaponin,KS)治疗慢性支气管炎的作用机制。将50只健康小鼠分成正常对照组、模型组和桔梗皂苷低、中、高剂量组,除正常对照组外,其余四组动物均采用烟熏加浓氨水吸入法建立慢性支气管炎模型,然后分别用药物进行治疗。实验结束后,取各组小鼠肺组织进行石蜡制片,HE染色光镜观察支气管和肺组织病理形态的变化;免疫组化分析肺细胞中IL-1β和TNF-α的表达。Western blot检测肺组织中IL-1β和TNF-α的表达。免疫组化检测显示,与正常对照组相比,模型组小鼠肺组织细胞中IL-1β和TNF-α的表达非常显著。在连续用药30天后,与模型组相比,各治疗组小鼠肺组织细胞中IL-1β和TNF-α的表达显著降低(P<0.05,P<0.01)。蛋白印迹术检测显示,模型组小鼠肺组织细胞中IL-1β和TNF-α的表达水平明显增加,与正常对照组比较,差异十分显著(P<0.01)。而连续用药30天后,各治疗组小鼠肺组织细胞中IL-1β和TNF-α的表达量明显下降,且呈较好的量效关系。结果表明,桔梗皂苷对慢性支气管炎小鼠肺组织中炎性细胞因子IL-1β和TNF-α的表达有明显的抑制作用。推测其作用机制可能是通过抑制肺组织中炎性细胞因子和自由基的生成而达到抗炎、止咳平喘作用的。     

Pseudomonas aeruginosa A2 elastase: purification, characterization and biotechnological applications

An extracellular protease from Pseudomonas aeruginosa A2 grown in media containing shrimp shell powder as a unique source of nutriments was purified and characterized. The enzyme was purified to homogeneity from culture supernatant by ultrafiltration, Sephadex G-100 gel filtration and Sepharose Mono Q anion exchange chromatography, with a 2.23-fold increase in specific activity and 64.3% recovery. The molecular mass of the enzyme was estimated to be 34 kDa. Temperature and pH with highest activity were 60 °C and 8.0, respectively. The protease activity was inhibited by EDTA suggesting that the purified enzyme is a metalloprotease. The enzyme is stable in the presence of organic solvents mainly diethyl ether and DMSO. The lasB gene, encoding the A2 elastase, was isolated and its DNA sequence was determined. The A2 protease was tested for shrimp waste deproteinization in the process of chitin preparation. The percent of protein removal after 3 h hydrolysis at 40 °C with an enzyme/substrate (E/S) ratio of 5 U/mg protein was about 75%. Additionally, A2 proteolytic preparation demonstrated powerful depilating capabilities of hair removal from bovine skin. Considering its promising properties, P. aeruginosa A2 protease may be considered a potential candidate for future use in several biotechnological processes.     

Nitrogen-enhanced herbaceous competition threatens woody species persistence in a desert ecosystem

Plant and Soil - Water and nitrogen availability are primary determinants of woody communities in dryland ecosystems and are strongly affected by global change. However, the mechanisms by which...