Carbohydrate-rich compounds in the colonic mucosa of man. 3. A preliminary report of some biochemical characteristics of the carbohydrate-rich components in normal colonic mucosa

Chemical and histochemical studies of normal and diseased human gastrointestinal tract. I. A comparison between histologically normal colon, colonic tumours, ulcerative colitis and diverticular disease of the colon

Chemical and histochemical methods were used to compare the epithelial glycoproteins from formalin-fixed surgical specimens of normal human large intestine, colonic tumours, ulcerative colitis and diverticular disease. All the epithelial glycoproteins contained fucose, galactose, glucosamine, galactosamine and, in addition, sialic acids both with and without O-acyl substituents in the side chain and/or at position C4. The glycoproteins of the normal ascending and descending colons differed significantly with respect to the percentage of the sialic acids released following digestion of the de-O-acylated glycoprotein with Vibrio cholera neuraminidase and to the molar fucose-sialic acid ratio. Statistical analysis of the chemical data showed that (a) compared to normal, the sialic acids of the tumour and ulcerative colitis glycoproteins from the descending colon were significantly less substituted in the side chain and at position C4; (b) the O-acetyl substitution pattern of the sialic acids of the ulcerative colitis glycoproteins from the ascending colon and the quantitative composition of the carbohydrate prosthetic groups of the ulcerative colitis glycoproteins from both ascending and descending colons differed from normal; (c) it was not always possible to distinguish between the ulcerative colitis and tumour glycoproteins on the basis of the O-acetyl substitution pattern of their sialic acids; and (d), there were minor differences between normal glycoproteins and those from cases of diverticular disease.

Changes in composition of mucin in the mucosa adjacent to carcinoma of the colon as compared with the normal: a biochemical investigation

Fifteen surgical specimens from patients with carcinoma of the colon and rectum were studied. Scrapings from normal mucosa distant from the tumour and from macroscopically normal mucosa adjacent to the tumour (;transitional') were used for chemical estimation of hexosamines, sialic acid, and proteins. The presence of hexosamines and sialic acid was confirmed in both normal and transitional mucosa. Transitional mucosa showed increased levels of total hexosamines and sialic acid as compared with the normal and this was accompanied by an increase in neuraminidase-sensitive sialic acids. The present data have been compared with previous histochemical and autoradiographic studies and it is suggested that the changes described in the transitional mucosa are transformations representing an early stage of carcinogenesis.