The use of Sep-Pak C18 reverse-phase cartridges to adsorb gangliosides from aqueous solutions was studied. When upper phases formed from chloroform-methanol tissue extracts or aqueous salt solutions containing gangliosides are rapidly passed through the cartridges, the lipids are retained and the non-lipid components can be washed through. Gangliosides and other retained lipids can subsequently be eluted with methanol or chloroform-methanol

Human milk protects suckling mice from the diarrheagenic effects of heat-stabile enterotoxin of Escherichia coli (ST). To identify the human milk fraction responsible for this protection, pooled skimmed, deproteinated milk was passed through charcoal, whereupon lactose was separated from the oligosaccharides. The oligosaccharides contained ST-protective activity; the lactose did not. The neutral, but not the acidic, fraction exhibited protective activity against ST (22% vs. 57% mortality, respectively; P less than .001). The fucosylated, but not the nonfucosylated, subfractions of the neutral fraction contained the factor protective against ST (35% vs. 50% mortality, respectively; P less than .05). An oligosaccharide isolation scheme based on different principles produced confirmatory results. The commercially available neutral fucosylated oligosaccharides of human milk did not significantly protect the mice from the effects of ST. Thus, the protective factor against ST seems to be a minor neutral fucosyloligosaccharide of human milk.