Elevated plasma enteroglucagon alone fails to alter distal colonic carcinogenesis in rats.
ABSTRACT The effect of physiologic increases of plasma enteroglucagon, induced by massive bypass or resection of small bowel, on large bowel cell turnover and carcinogenesis was studied in rats in which the distal colon was isolated as a mucous fistula. After injections of azoxymethane, either 85% end-to-side jejunoileal bypass, 85% jejunoileal resection, or sham bypass was performed. Controls underwent colonic transection and resuture, azoxymethane treatment, and then sham bypass. Thirty weeks later the plasma enteroglucagon level had almost trebled after jejunoileal bypass (p less than 0.001) and almost doubled after jejunoileal resection (p less than 0.002) when compared with sham bypass; sham values did not differ from controls. The median number of tumors per rat in the distal (defunctioned) colon fell from 2 to 0 (p less than 0.05). Segmental weight fell by 45% (p less than 0.001) and crypt cell production rate by 75% (p less than 0.001). Neither tumor yield nor adaptation was affected by jejunoileal bypass or jejunoileal resection. Plasma enteroglucagon has no effect on colonic cell turnover or carcinogenesis in the absence of luminal content.
- SourceAvailable from: ncbi.nlm.nih.gov[show abstract] [hide abstract]
ABSTRACT: The progress of adaptive changes in the left colon after diverting colostomy was studied in rats using stereological techniques. Standardised segments of left colon proximal and distal to the colostomy was examined after 0, 1, 2, 4, or 12 weeks. In excluded colon the mucosal weight was reduced by 37% (p < 0.01) and the luminal surface area by 47% (p < 0.01) after four weeks and reached a steady state at this point of time, as no further reduction was seen from 4 to 12 weeks. The number of proliferating crypt cells was determined immunohistochemically after in vivo labelling with bromodeoxyuridine and was compared with the total number of colonocytes. Total bowel rest leads to a reduction in the number of proliferating epithelial cells and not to a reduced average life span. The weight of the muscularis propria decreased by 32% after four weeks (p < 0.01) and by 48% after 12 weeks (p < 0.001), whereas the weight of the submucosa was unchanged. No adaptive changes were found in segments proximal to the colostomy. These results show that the wall composition of defunctioned colon in rats is radically changed resulting from a mucosal and muscular atrophy, and from a reduction in luminal surface area.Gut 09/1994; 35(9):1275-81. · 10.73 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The high incidence of clinical remission after faecal diversion for Crohn's colitis suggests the faecal stream may play a part in the inflammatory mechanism. The effect of faecal diversion (n = 22) and restoration of intestinal continuity (n = 10) was assessed in patients with Crohn's colitis and compared with controls. Faecal diversion produced significant improvement in the disease activity index mean (SEM) (before 176 (9); after 114 (9), p < 0.01) and serum albumin concentrations (before 33 (3.0); after 38 (3.0), p < 0.05) in all patients with Crohn's colitis. The crypt cell production rate (CCPR) was maintained after faecal diversion for Crohn's colitis but fell in the control group (before = 3.6 (0.8)), at two (1.4 (0.4), p < 0.02), and six weeks (1.6 (0.4), p < 0.05). Mucosal glucosamine synthetase activity, reflecting glycoprotein synthesis, was significantly lower in patients with Crohn's colitis (analysis of variance p < 0.05) after diversion but was maintained in the control group. Restoration of intestinal continuity failed to produce reciprocal changes. The sustained cellular proliferation and fall in glycoprotein synthesis in Crohn's colitis after faecal diversion may represent the end of an exaggerated protective response and regenerative hyperplasia after exclusion of the faecal stream. This study suggests the faecal stream may participate in the inflammatory process in Crohn's colitis. The underlying mechanism is unknown.Gut 02/1994; 35(2):236-42. · 10.73 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: A terminal ileal transposition procedure, in which a distal jejunal segment is interposed between the terminal ileum and the anus following proctocolectomy, is described. Adult mongrel dogs had either terminal ileal transposition (n = 5) or ileoanal anastomosis (n = 6) following two-stage proctocolectomy. Untreated dogs were used as controls (n = 7). Twelve weeks after the second-stage operation, a perfusion study was performed. After terminal ileal transposition the transposed terminal ileum showed a high absorptive capability for sodium, chloride and bile acids (P < 0.05, P < 0.05 and P < 0.001 respectively). After ileoanal anastomosis the absorptive capability of the terminal ileum was not enhanced significantly. In the mid-jejunum, the absorption of bile acids, chloride and glucose was enhanced (all P < 0.05) only after terminal ileal transposition. Terminal ileal transposition improves the absorptive capability of the terminal ileum and the mid-jejunum compared with conventional ileoanal anastomosis in this model.British Journal of Surgery 05/1996; 83(4):486-92. · 4.84 Impact Factor