Evaluation of the role of in vivo proteolysis (fibrinogenolysis) in prolonging the thrombin time of human umbilical cord fibrinogen

These studies have been directed at evaluating the role played by proteolysis (fibrinogenolysis) in vivo in prolonging the thrombin time of human umbilical cord ("fetal") fibrinogen. The aggregation rate of cord fibrin compared with that from adult plasma is always delayed when the reaction is carried out under conditions of relatively high ionic strength (e.g., 0.29); this difference is not apparent at relatively low ionic strength (e.g., 0.09). In addition, as assessed by turbidimetric techniques, the maximum absorbance attained by cord fibrin is considerably less than that attained by adult fibrin. Coagulable fibrinogen catabolites (i.e., fraction I-5) are present in cord plasma and, like their counterparts from adult plasma, lack various portions of the COOH-terminal region of the A alpha chain. However, their presence in plasma does not explain the behavioral differences between cord and adult fibrin. Moreover, differences revealed by turbidimetric comparison of cord and adult fibrin from plasma fraction I-2 persist in fibrin from fraction I-5; it therefore appears that the COOH-terminal region of the A alpha chain does not contain the structure(s) accounting for the unique behavior of "fetal" fibrinogen.     

Interaction of single-chain urokinase with its receptor induces the appearance and disappearance of binding epitopes within the resultant complex for other cell surface proteins

Binding of urokinase-type plasminogen activator (uPA) to its glycosylphosphatidylinositol-anchored receptor (uPAR) initiates signal transduction, adhesion, and migration in certain cell types. To determine whether some of these activities may be mediated by associations between the uPA/uPAR complex and other cell surface proteins, we studied the binding of complexes composed of recombinant, soluble uPA receptor (suPAR) and single chain uPA (scuPA) to a cell line (LM-TK- fibroblasts) that does not express glycosylphosphatidylinositol (GPI)-anchored proteins to eliminate potential competition by endogenous uPA receptors. scuPA induced the binding of suPAR to LM-TK- cells. Binding of labeled suPAR/scuPA was inhibited by unlabeled complex, but not by scuPA or suPAR added separately, indicating cellular binding sites had been formed that are not present in either component. Binding of the complex was inhibited by low molecular weight uPA (LMW-uPA) indicating exposure of an epitope found normally in the isolated B chain of two chain uPA (tcuPA), but hidden in soluble scuPA. Binding of LMW-uPA was independent of its catalytic site and was associated with retention of its enzymatic activity. Additional cell binding epitopes were generated within suPAR itself by the aminoterminal fragment of scuPA, which itself does not bind to LM-TK- cells. When scuPA bound to suPAR, a binding site for alpha 2-macroglobulin receptor/LDL receptor-related protein (alpha 2 MR/LRP) was lost, while binding sites for cell-associated vitronectin and thrombospondin were induced. In accord with this, the internalization and degradation of cell-associated tcuPA and tcuPA-PAI- 1 complexes proceeded less efficiently in the presence of suPAR. Further, little degradation of suPAR was detected, suggesting that cell- bound complex dissociated during the initial stages of endocytosis. Thus, the interaction of scuPA with its receptor causes multiple functional changes within the complex including the dis-appearance of an epitope in scuPA involved in its clearance from the cell surface and the generation of novel epitopes that promote its binding to proteins involved in cell adhesion and signal transduction.     

Self-rated health,work characteristics and health related behaviours among nurses in Greece: a cross sectional study

Background  

Previous studies on self-rated health among nurses have indicated an association of low job satisfaction and stress in relation to poor self-rated health. The relationship between self rated health and the specific work characteristics and health related behaviours of nurses to our knowledge have not been adequately studied.     

楤木根皮中皂甙化学成分的研究

楤木根皮中的主要成分是皂甙。将总皂甙以柱层析分离,得到三个化合物(Ⅰ～Ⅲ),经光谱分析和化学方法证明,Ⅰ为楤木皂甙A(araloside A);Ⅱ为银莲花甙(narcissiflorine);Ⅲ是3-O-[β-D-吡喃葡萄糖-(1→2)-β-D-吡喃木糖-(1→)2)-α-L-阿拉伯糖]-齐墩果酸。Ⅲ为一新皂甙,命名为楤木皂甙D(araloside D)。     

蛇床子素对豚鼠离体回肠和结肠带的作用

以豚鼠离体回肠和结肠带为标本,观察蛇床子素(Ost)的作用与Ca~(2+)的关系。结果表明:Ost和钙拮抗剂Ver产生剂量依赖性抑制乙酰胆碱(ACh)、组胺及KCl所致回肠条或结肠带的收缩;非竞争性拮抗CaCl_2累积量—效曲线,pD_2分别为4.41±0.15,7.0±0.2。Ost 100μmol/L和Ver 1μmol/L均能对抗小剂量Ca~(2+)所致结肠带收缩,但被加入较大量Ca~(2+)所取消。Ost和Ver均能抑制ACh诱导的依内钙性收缩,不影响依外钙性收缩。结果提示Ost具有钙拮抗作用,其作用方式与Ver类似。     

孤啡肽在脑内对抗电针镇痛在脊髓加强电针镇痛

目的：观察孤啡肽（ＯＦＱ）是否影响电针镇痛。方法：通过侧脑室和脊髓蛛网膜下腔慢性埋植瘘管，分别在大鼠脑内和脊髓内注射ＯＦＱ，观察其对电针镇痛效应的影响。结果：首次发现ｉ．ｃ，ｖ，注射ＯＦＱ１ｎｍｏｌ和１０ｎｍｏｌ，可剂量依赖地对抗高频（１００Ｈｚ）电针镇痛，而ｉ．ｔ．注射ＯＦＱ３ｎｍｏｌ和１０ｎｍｏｌ可剂量依赖地加强高频电针镇痛。结论：孤啡肽在脑内对抗电针镇痛，在脊髓加强电针镇痛。