In vitro studies on origin and site of action of enzyme activity responsible for conversion of human proapoprotein A-I into apoprotein A-I

Human hepatocellular carcinoma cells (Hep G2) were shown to secrete apo A-I as a proprotein. No apo A-I synthesis could be detected with endothelial cells from human umbilical cord veins. Conversion of proapo A-I into apo A-I is a slow (of the order of hours) process, mediated by a Ca2+/Mg2+-dependent enzyme which is present on the surface of...

Low density lipoprotein metabolism by endothelial cells from human umbilical cord arteries and veins

Binding and metabolism of low density lipoprotein (LDL) and acetylated LDL were examined in endothelial cells from human umbilical cord arteries and veins. Both high and low affinity LDL interactions were observed. High affinity LDL binding and catabolism were increased five- to sevenfold after preincubation for 18 hours in LPDS containing...

The metabolism in vitro of human low-density lipoprotein by the human hepatoma cell line Hep G2

The human hepatoma cell line Hep G2 was studied with respect to metabolism of human low-density lipoprotein (LDL). The Hep G2 cells bind, take up and degrade human LDL with a high-affinity saturable and with a low-affinity non-saturable component. The high-affinity binding possesses a K(D) of 25 nM-LDL and a maximal amount of binding of about 70...

Response of fibrinolytic activity and factor VIII-related antigen to stimulation with desmopressin in hyperlipoproteinemia

Impairment of fibrinolysis is supposed to contribute to CVD. In 38 hyperlipoproteinemic patients, known to be at risk for early CVD, fibrinolytic activity was measured before and after stimulation with DDAVP. A negative correlation was found between serum triglyceride levels and fibrinolytic activity, both before and after DDAVP. A subnormal...

Immunoelectronmicroscopy of the binding of high density lipoprotein apoproteins to normal and hypercholesterolemic human fibroblasts

We visualized the apolipoproteins of high density lipoproteins (HDL) that were bound to cultured human fibroblasts at the ultrastructural level, with an immunoenzymecytochemical method. By using antisera against (a) apolipoprotein AI (a major apolipoprotein of HDL) and (b) apolipoprotein E (an apolipoprotein present in HDL), the binding of HDL...

Complications in the determination of HDL2/HDL3 ratios

We investigated different procedures to subfractionate high density lipoprotein (HDL) into its density subfractions (HDL2 and HDL3). When pore-limit as well as zone polyacrylamide gel electrophoresis was used, it proved to be necessary to use freshly prepared and plasma protein-free HDL preparations. For a quantitative subfractionation of HDL in...

Binding of LP(a) to the low density lipoprotein receptor of human fibroblasts

Chemicals/CAS: Lipoprotein(a); Lipoproteins; Lipoproteins, LDL; Receptors, Cell Surface; Receptors, LDL

Suppression of cholesterol synthesis in cultured fibroblasts from a patient with homozygous familial hypercholesterolemia by her own low density lipoprotein density fraction. A possible role of apolipoprotein E

The suppression of cellular cholesterol synthesis by low density lipoprotein (LDL) from a normal and from a homozygous familial hypercholesterolemic subject was measured on normal fibroblasts and on fibroblasts derived from the same homozygous familial hypercholesterolemic patient. On normal fibroblasts both LDL preparations (density 1.019 to 1...

Lipoprotein secretion by isolated rat hepatocytes: Characterization of the lipid-carrying particles and modulation of their release

Lipoprotein production by freshly isolated rat hepatocytes in suspension was studied during short (1-3 hr) incubation periods. The heaptocytes release very low density (91.10 g/ml). These particles with higher densities have not been positively identified; the latter group is dissimilar to the high density lipoprotein, which occurs in rat liver...

The effect of a fish diet on serum lipids in healthy human subjects

A cross-over study was done with 19 male and 23 female volunteers living in a monastery and a convent, respectively. The effect of a fat fish (mackerel) diet on the blood serum lipid composition was studied. As the normal diet of these volunteers was of the lacto-ovo-vegetarian type, a control diet in which the fish was replaced by full-fat...

Resting levels of blood fibrinolysis in hyperlipoproteinemia

To correlate resting levels of blood fibrinolysis with different types of hyperlipidemia, the concentrations of fibrinogen and plasminogen and the euglobulin activity (precipitated at pH 5.9 and assayed on fibrin plates prepared with bovine, plasminogen-rich fibrinogen) were determined in fasting plasma samples from a group of normal controls (...