Binding and transfer of verocytotoxin by polymorphonuclear leukocytes in hemolytic uremic syndrome

The hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children. The role of a verocytotoxin (VT)-producing Escherichia coli has been strongly implicated in the epidemic form of HUS. Although direct toxicity of VT on glomerular endothelial cells has been demonstrated, it remained still unclear how the VT is...

Binding of β-VLDL to heparan sulfate proteoglycans requires lipoprotein lipase, whereas apoE only modulates binding affinity

The binding of β-VLDL to heparan sulfate proteoglycans (HSPG) has been reported to be stimulated by both apoE and lipoprotein lipase (LPL). In the present study we investigated the effect of the isoform and the amount of apoE per particle, as well as the role of LPL on the binding of β-VLDL to HSPG. Therefore, we isolated β-VLDL from transgenic...

Fibrinolytic activity of human mesothelial cells is counteracted by rapid uptake of tissue-type plasminogen activator

Background. Human mesothelial cells (HMCs) have an important role in maintaining an adequately functioning fibrinolytic system in the peritoneal cavity by secreting the fibrinolytic enzymes tissue-type and urokinase-type plasminogen activator (t-PA and u-PA), as well as a specific PA inhibitor, PA inhibitor type 1 (PAI-1). In this study, we...

The role of the low-density lipoprotein receptor-related protein (LRP) in the plasma clearance and liver uptake of recombinant single-chain urokinase-type plasminogen activator in rats

Urokinase-type plasminogen activator (u-PA) is used as a thrombolytic agent in the treatment of acute myocardial infarction. In vitro, recombinant single-chain u-PA (rscu-PA) expressed in E. coli is recognized by the Low-Density Lipoprotein Receptor-related Protein (LRP) on rat parenchymal liver cells. In this study we investigated the role of...

Lipolysis of very low density lipoproteins by heparan sulfate proteoglycan-bound lipoprotein lipase

An in vitro assay to study lipolysis of very low density lipoproteins (VLDL) by heparan sulfate proteoglycan (HSPG-bound lipoprotein lipase (LPL) was developed. Optimal conditions for VLDL lipolysis by HSPG-bound LPL were obtained by incubating plastic wells with 0.5 ug HSPG and 1.5 ug LPL, subsequently. Control experiments with heparinase...

Low-density lipoproteins are degraded in HepG2 cells with low efficiency

In previous studies we have shown that in HepG2 cells, as compared with fibroblasts, the low-density lipoprotein (LDL) receptor is only weakly down-regulated upon incubation of the cells with LDL. To explain this difference in down-regulation of the LDL-receptor activity, we studied simultaneously the intracellular processing of 125I-labelled...

Characterization of the interaction both in vitro and in vivo of tissue-type plasminogen activator (t-PA) with rat liver cells. Effects of monoclonal antibodies to t-PA

The interaction of 125I-labelled tissue-type plasminogen activator (125I-t-PA) with freshly isolated rat parenchymal and endothelial liver cells was studied. Binding experiments at 4°C with parenchymal cells and endothelial liver cells indicated the presence of 68000 and 44000 high-affinity t-PA-binding sites, with an apparent K(d) of 3.5 and 4...

In vivo and in vitro interaction of high and low molecular weight single-chain urokinase-type plasminogen activator with rat liver cells

The plasma clearance and the interaction of high (HMW) and low (LMW) molecular weight single-chain urokinase-type plasminogen activator (scu-PA) with rat liver cells was determined. 125I-Labeled HMW- and LMW-scu-PA were rapidly cleared from plasma with a half-life of 0.45 min and a maximal liver uptake of 55% of the injected dose. Liver uptake...

Partial characterization of low density lipoprotein preparations isolated from fresh and frozen plasma after radiolabeling by seven different methods

Four 99mTc and three 123I labeling methods were evaluated for their suitability to label low density lipoproteins (LDL) for the purpose of scintigraphic biodistribution studies. For 99mTc these methods were: direct incorporation in LDL of 99mTcO4- using sodium dithionite (dithionite method); a method using first N,N-dimethylformamide to prepare...

Evidence for the occurrence of a fast-acting inhibitor for tissue-type plasminogen activator in human plasma

Human plasma contains a fast-acting t-PA inhibitor, which is not identical with ??2-antiplasmin or ??2-macroglobulin. The concentration of this inhibitor in normal plasma is highly variable, much lower than that of known plasma protease inhibitors, and in the range of physiologically occurring plasma concentrations of t-PA (0-2 IU/ml). The...