细菌内毒素检查法超标结果的处理方法

 内毒素检测结果超过质量标准规定（OOS）的情况在日常检测中不可避免。通过风险因素分析法,结合大量实际工作经验,对产生OOS的原因进行了逐项分析和研究,包括质量标准与计算、实验操作、材料与仪器等因素。针对内毒素检查的特性,设计决策流程图确定验证OOS方案。确定了所有类型的风险因素产生原因和解决方法,建立了用于回顾细菌内毒素OOS的风险因素鱼骨图和用于验证OOS结果的决策流程图。按建立的方法进行验证处理OOS,能够使内毒素检测结果更加科学严谨。     

In vivo reprogramming of murine cardiac fibroblasts into induced cardiomyocytes

The reprogramming of adult cells into pluripotent cells or directly into alternative adult cell types holds great promise for regenerative medicine. We reported previously that cardiac fibroblasts,which represent 50%of the cells in the mammalian heart, can be directly reprogrammed to adult cardiomyocyte-like cells in vitro by the addition of Gata4, Mef2c and Tbx5 (GMT). Here we use genetic lineage tracing to show that resident non-myocytes in the murine heart can be reprogrammed into cardiomyocyte-like cells in vivo by local delivery of GMT after coronary ligation. Induced cardiomyocytes became binucleate, assembled sarcomeres and had cardiomyocyte-like gene expression. Analysis of single cells revealed ventricular cardiomyocyte-like action potentials, beating upon electrical stimulation, and evidence of electrical coupling. In vivo delivery of GMT decreased infarct size and modestly attenuated cardiac dysfunction up to 3 months after coronary ligation. Delivery of the pro-angiogenic and fibroblast-activating peptide, thymosin b4, along with GMT, resulted in further improvements in scar area and cardiac function. These findings demonstrate that cardiac fibroblasts can be reprogrammed into cardiomyocyte-like cells in their native environment for potential regenerative purposes.     

昆明小鼠胚胎成纤维细胞的分离与体外培养

研究了昆明小鼠胚胎成纤维细胞的分离、培养和生长特征,建立了快速、稳定的优质饲养层细胞培养体系.从不同日龄的胎鼠均分离到胚胎成纤维细胞,但最佳分离时间为13.5~14.5d;三种分离原代胚胎成纤维细胞的方法中胰酶消化法效果最好,能在较短的周期内获得大量原代及传代细胞;MEF细胞形态以小梭形为主,呈漩涡状、火焰状生长;增殖速度较快,每1~2d可传一代,按1∶3比例常规传代;5代以内适宜制作饲养层用,5代以后细胞开始变形呈现典型的衰老特征.     

注射用头孢西丁钠细菌内毒素检查法与热原检查法的比较

目的:通过细菌内毒素检查法与热原检查法的比较实验,建立注射用头孢西丁钠的细菌内毒素检查法.方法:通过家兔试验确定注射用头孢西丁钠的致热阈值、内毒素限值,选用鲎试剂灵敏度为0.125 EU·mL-1样品质量浓度设定为0.83 mg·mL-1;鲎试剂灵敏度为0.25 EU·mL-1样品质量浓度设定1.66 mg·mL-1两种不同质量浓度为干扰实验质量浓度确定头孢西丁钠的试验质量浓度.结果:注射用头孢西丁钠对细菌内毒素的干扰作用可以通过稀释的方法排除,最后确定限度为每1 mg含细菌内毒素不高于0.13 EU.结论:注射用头孢西丁钠可用于细菌内毒素检查法代替家兔法进行热原检查.     

Antisense oligodeoxynucleotides to GS protein alpha-subunit sequence accelerate differentiation of fibroblasts to adipocytes.

Fully-differentiated mouse 3T3-L1 fibroblasts accumulate large amounts of lipid at 7-10 days after induction by insulin or by dexamethasone and a methyl xanthine. G proteins mediate transmembrane signalling from a diverse group of cell-surface receptors to effector units that include phospholipase C, adenylyl cyclase and ion channels. They are also targets of regulation themselves. 3T3-L1 fibroblasts display marked changes in levels of G protein when induced to differentiate to adipocytes. Here we show that cholera toxin, which ADP-ribosylates and activates the G protein subunit Gs alpha, blocks the induction of differentiation, whereas increasing intracellular cyclic AMP directly with the dibutyryl analogue or indirectly with pertussis toxin or forskolin does not affect differentiation. Oligodeoxynucleotides antisense to the sequence encoding Gs alpha accelerate differentiation markedly. The time course of adipogenesis declined from 7-10 days in controls to roughly 3 days in cultures treated with antisense-Gs alpha oligodeoxynucleotides, whereas oligodeoxynucleotides, antisense to Gi alpha 1, Gi alpha 3, and sense and missense to Gs alpha, had no such effect. Antisense-Gs alpha alone induced differentiation by day 7, indicating that Gs alpha activity modulates differentiation in 3T3-L1 cells, acting in a new role which is independent of increased intracellular cAMP.     

Recognition and plasma clearance of endotoxin by scavenger receptors.

Lipid A is the active moiety of lipopolysaccharide (LPS, also referred to as endotoxin), a surface component of Gram-negative bacteria that stimulates macrophage activation and causes endotoxic shock. Macrophages can bind, internalize and partially degrade LPS, lipid A and its bioactive precursor, lipid IVA. We report here that lipid IVA binding and subsequent metabolism to a less active form by macrophage-like RAW 264.7 cells is mediated by the macrophage scavenger receptor. Scavenger-receptor ligands inhibit lipid IVA binding to, and metabolism by, RAW cells, and lipid IVA binds to type I and type II bovine scavenger receptors on transfected Chinese hamster ovary cells. Although in vitro competition studies with RAW cells indicate that scavenger receptor binding is not involved in LPS or lipid IVA-induced stimulation of macrophages, in vivo studies show that scavenger-receptor ligands greatly inhibit hepatic uptake of lipid IVA in mice. Thus, scavenger receptors expressed on macrophages may have an important role in the clearance and detoxification of endotoxin in animals.