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UBC Theses and Dissertations

Histochemical changes in colonic epithelial glycoproteins during the induction of cancer in rats Lazosky, Darien-Alexis


Colonic epithelial glycoproteins were histochemically studied in rats during the induction of colorectal cancer with 1,2,-dimethylhydrazine-diHCl (DMH). 310 male Wistar rats were separated into 3 groups: 10 control rats were sacrificed without treatment, 150 rats were given weekly subcutaneous injections of the carcinogen and 150 rats were given sham Injections on the same schedule. Groups of rats (10 control and 10 treated) were sacrificed at various time intervals in an effort to obtain a large number of pre-neoplastic rat colons to be used to determine whether histochemical changes could be detected prior to morphologic change. Three histochemically distinct regions in the Wistar rat distal colon have been described using recently developed techniques. Two major histochemical changes have been shown to occur prior to malignancy. Change 'A' represented a decrease or loss of sulphate from the glycoproteins; this was the earliest and predominant change and has been shown to occur prior to any identifiable morphologic change. Change 'B' represented a decrease or loss of sulphate occurring in the same cells as a decrease or loss of side chain 0-acetylation of sialic acid residues; this change occured later and to a lesser extent than change 'A'. The data suggests that histochemical change may be a premalignant marker, however, further investigations are necessary to firmly establish this conclusion.

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