Abnormalities in colonic glycoprotein synthesis have been implicated i
n the pathogenesis of ulcerative colitis and Crohn's disease. Glucosam
ine synthetase is the rate-limiting step in the biosynthesis of gastro
intestinal glycoprotein and has been measured in control subjects (N =
23) and patients with ulcerative colitis (N = 26) or Crohn's disease
of the colon (N = 20) classified according to the macroscopic status o
f the rectum. Glucosamine synthetase activity was relatively constant
around the normal colon but lower levels were found in the terminal il
eum. In ulcerative colitis, glucosamine synthetase activity was simila
r to controls (24.0 +/- 1.9) mmol/g wet (wt/hr) irrespective of diseas
e activity (quiescent: N = 13, = 27.3 +/- 1.9; active N = 16, = 26.2 /- 2.3). Rectal glucosamine synthetase activity was normal in the pres
ence of active Crohn's proctocolitis (29.4 +/- 3.1) but raised in pati
ents with Crohn's colitis and rectal sparing (37.2 +/- 4.9 P < 0.02).
Glucosamine synthetase activity was strongly influence by the degree o
f epithelial preservation.