William A. Olsen

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We have studied small intestinal absorption of carnitine in vivo using a combination of segmental perfusion techniques and bolus intraluminal injection. We found evidence of a partially saturable absorption process (with Km values of 1035 and 1267 microM for jejunum and ileum calculated for the saturable component) that appeared to be separate from the(More)
Relative deficiency of intestinal lactase activity during adulthood, adult hypolactasia, is a common condition worldwide. We studied the regulation of lactase-phlorizin hydrolase in normal and adult hypolactasic subjects by correlating transcript abundance in intestinal biopsies with relative synthetic rates for the protein in cultured intestinal explants.(More)
The specificity and mechanism of altered intestinal transport of diabetic rats was studied with an everted ring technique. Increased intracellular accumulation of amino acids, as well as galactose and 3-O-methylglucose, was demonstrated in diabetes. The greater accumulation by diabetic intestine could not be attributed to a direct effect of the agent used(More)
Although carnitine is present in a variety of foods, the mechanism of its absorption has not been previously studied in humans. We investigated the absorption of carnitine by studying uptake into human intestinal mucosal biopsy specimens. We found evidence of active transport in the duodenum and ileum, but not in the colon. We demonstrated that(More)
Although L-carnitine has been given orally to patients with systemic carnitine deficiency with successful control of the disease and is present in a variety of dietary sources, there is little available information on the physiology of its absorption. We therefore studied intestinal carnitine absorption in the rat by measuring the uptake of radioactive(More)
We previously determined that the L-carnitine uptake by human duodenal tissue occurs by both active (KT 558 mumol/L) and passive mechanisms. The effects of enteral carnitine was studied in humans. A hamburger meal (345 mumol total carnitine) induced peak jejunal fluid free (unesterified) and short-chain acylcarnitine concentrations (SCAC) of 209 and 130(More)
A commercial alpha-amylase inhibitor with potent inhibitory activity in vitro was used in a randomized double-blind, cross-over clinical trial in six nonobese, healthy adult males. In these subjects, this inhibitor had no effect on the response of blood glucose, insulin, or breath hydrogen to a standardized starch meal. It is concluded that this formulation(More)
Although a variety of plant lectins are consumed as part of the normal human diet and are capable of binding to intestinal cell surfaces in vitro, little information exists on their effects on intact intestine. We have studied the acute effects of intraluminal administration of wheat germ agglutinin and concanavalin A in normal rats. Both lectins caused(More)
The effect of luminal sodium on intestinal glucose absorption at a variety of glucose concentrations was studied with a segmental perfusion technique in normal subjects. Uphill glucose transport was inhibited with sodium-free perfusions with either mannitol or Tris-HCl as the osmotic replacement of sodium (P < 0.01-P < 0.001). This effect did not appear to(More)
Ricinoleic acid, the active component of castor oil, and related fatty acids were studied to determine their relative inhibitory effects on water and electrolyte absorption using everted hamster jejunal and ileal segments. Differences were found between hydroxylated and nonhydroxylated congeners as well as between cis and trans geometric isomers. At a(More)