MUCZ and MUC3 are prominent mucin genes expressed in the human intestine. Using in situ hybridization with RNA probes, we examined the cellular distribution of MUC2 and MUC3 mRNA in normal, malignant, and inflamma tory human intestinal tissues. In normal small intestine and colon, MUCZ mRNA was expressed exclusively in goblet cells and occurred throughout the entice height of the mucosa. MUC3 mRNA was expressed by goblet and columnar cells but was restricted to the villous com tment of the s m a l l intestine and MUC3 mRNA were both markedly decreased in poorly, moderately, and well-di&rentiated colon cancers but were preserved in mucinous colon cancers. In ulcerative colitis and Crohn's colitis tissues, MUC2 and MUC3 "A expression and the surface epithelium o r the colon. Expression of MUCZ

SUMMARY Conjugation of phenol by the colonic mucosa was assessed in vivo using dialysis tubing containing 15 ml of 1 mmol/l acetaminophen (paracetamol) and 10 mmol/l butyrate. These were allowed to equilibrate in the rectum for one hour. The glucuronidated and sulphated conjugates of acetaminophen were measured by high pressure liquid chromatography and bicarbonate concentrations by gas analysis. In 21 subjects without colonic disease sulphate conjugation was observed in all cases, with a mean (SE) of 3-86 (0-66) nmol/hour, while glucuronide conjugation was found in seven of 21 cases. Mean (SE) bicarbonate output of42 9 (3 9) ,mol/hour (n = 21) indicated healthy colonic mucosal metabolism and phenolic sulphation in dialysate and agreed with published sulphation rates obtained with cultured cells of colonic epithelium.Acetaminophen sulphation suggests that the colonic mucosa has an important role in the conjugation of phenols, and the method reported here would be useful in assessing the detoxification capacity of the colonic mucosa in diseases of the rectal mucosa.Relatively little attention has been directed towards the capacity of the colonic mucosa to inactivate dietary or bacterial phenols. Self