Intestinal permeability and reagents

Intestinal permeability was determined by quantification of urinary excreted sugars after ingestion of an oral sugar cocktail [42–44]. The oral sugar cocktail was taken by the HC subjects seven days after the endoscopic sigmoid colon mucosa and fecal specimens were collected. Fasted HC subjects were given an oral cocktail of 40 g sucrose, 2 g mannitol, 7.5 g lactulose mixed in 8 oz. of water and 1 g sucralose in two capsules at 6 AM, and then urine was collected for 24 hours. Urinary concentrations of excreted sugars were determined using gas chromatography and an internal standard as previously described [42,44]. The intestinal permeability results were expressed as percent excretion of oral dose of the various sugars as previously described [42,44].

Lactulose (4-o-β-D-galactopyranosyl-D-fructofuranose) was obtained from Bertek Pharmaceuticals, as brand name Kristalose. Mannitol (D-mannitol) and sucrose (α-D-glucopyranosyl-β-D-fructofuranoside) were obtained from Sigma Aldrich. Sucralose (1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-glucopyranoside) was supplied by Tate and Lyle. Trifluoroacetic acid ammonia, sodium borodeuteride, acetone, acetic anhydride and glacial acetic acid were purchased at their highest grade purity from Sigma Aldrich.