Adsorption of fibrinogen on to polystyrene latex coated with the non-ionic surfactant, poloxamer 338.

We have measured the isothermal adsorption of 125I-fibrinogen on to polystyrene latex (PSL), which was prepared without surfactants, and on to PSL with an adsorbed coat of poloxamer 338 (an A-B-A block copolymer where A is poly(oxyethylene) and B is poly(oxypropylene]. The plateau adsorption of fibrinogen, at 310 K, was significantly lower on to latex coated with poloxamer 338. Previous studies have shown that poloxamer 338-coated PSL is cleared less avidly than uncoated PSL by cells of the mononuclear phagocytic system (MPS). Our findings are quantitative evidence in support of the theory that the uptake of colloids by the MPS can be related to the interfacial adsorption of opsonic proteins.

A comparison of the effects of feeding linoleic acid-rich lecithin or corn oil on cholesterol absorption and metabolism in the rat.

Either purified soya phosphatidylcholine (lecithin) or triacylglycerol (corn oil) were fed to rats on a diet containing 0.5% cholesterol. The diets contained similar amounts of linoleic acid. The effects of the two preparations on (a) serum cholesterol concentrations, (b) fatty acid profiles, (c) HMG-CoA reductase activity, (d) cholesterol absorption, and (e) faecal excretion of neutral sterols are compared. Some comparisons are also made with diets containing saturated triacylglycerol (lard) and no additional fats other than cholesterol. Serum cholesterol levels were less markedly raised on the lecithin diet, compared with the corn oil or lard diets. Evidence is presented that lecithin reduces the absorption of dietary cholesterol and also increases the excretion of neutral sterols. Our results suggest that soya lecithin is a more potent hypocholesterolaemic agent than corn oil.