NUTRIENT ABSORPTION AND MALABSORPTION

Interesting new data was generated during the past year with respect t o lipid metabolism, molecular biology, polyamine metabolism, bile salt absorption, electrolytes, and peptide and amino acid absorption in th e intestine. The chylomicron remnants were shown to be taken up by ent eroyctes in a receptor-dependent manner. An apolipoprotein B knockout mouse in which a human apolipoprotein B-100 transgene was inserted was produced in which the liver but not the intestine expressed apolipopr otein B, resulting in impaired lipid export from the intestine. The ho meobox gene, cdx-2, was shown to be important in cellular differentiat ion. The ontogeny of the sodium-dependent bile acid transporter was de scribed. GLUT-5 was shown to be regulated in part by substrate load. S ite-directed mutagenic studies identified the active site of lactase.