HISTOCHEMICAL ALTERATIONS OF MUCIN IN NORMAL COLON, INFLAMMATORY BOWEL-DISEASE AND COLONIC ADENOCARCINOMA

Loss of sialic acid o-acyl substitutions in colonic mucus was studied using specific histochemical techniques in individuals with a variety of large-bowel diseases and in a control population. Changes found inc luded a focal or field (diffuse) loss of side-chain substitutions whic h were qualitatively similar in all groups studied. The results were t ested statistically using a variety of assumptions that field and/or f ocal loss of o-acyl substitution may be either abnormal or a normal va riant. No statistically significant differences in the prevalence of s ubstitutions were detected between normal males and females or between normal individuals aged 0-29 years and 30-80 years. Significant diffe rences were found between ascending and descending colon in both norma l individuals and in the non-neoplastic mucosa of patients with cancer . There were also significant differences between the normal descendin g colon and cases with cancer of the descending colon. These differenc es seem unlikely to be due to non-specific factors, since for most ass umptions there were also differences between colons containing cancer and those from patients with inflammatory bowel disease. In agreement with the work of other investigators, it seems likely that focal loss of o-acetylation results from an acquired gene mutation. It is not cle ar whether or not this plays a role in carcinogenesis.