http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
effect on cellular events and role in protection against colon cancer
xiv, 227 leaves : illustrations ; 28 cm.
Colon cancer is a common and deadly human disease that is
strongly linked to dietary and environmental factors, both in
initiation and progression of tumorigenesis. Dietary fibers
and one of their byproducts, butyrate, are alternately linked
to prevention or promotion of tumor development. Poorly
fermented dietary fibers, such as wheat bran or cellulose,
are believed to be protective. Conversely, highly fermented
fibers, such as pectin or oat bran, may not be protective.
Butyrate production by fiber fermentation may be an important
part of its protective effects, because of the apparently
different effects butyrate has on normal versus transformed
colonocytes. Thus, this investigation was undertaken to
study the effects of two different fibers, wheat bran and oat
bran, and their fermentation by-product, butyrate on luminal
pH, intracellular pH, cell cycle indices and apoptosis in
freshly isolated colonocytes and on the development of tumors
in a rodent model of colon cancer. The results of this
investigation have addressed several major issues relating to
colon cancer development and dietary fiber supplementation.
Rats consuming oat bran diets produced the largest
concentrations of butyrate, yet developed significantly more
and larger tumors than rats consuming wheat bran diets. Oat
bran rats also had lower luminal pH values, which was
predicted to be protective, but was not correlated with
decreased tumor incidence. Intracellular pH was more
alkaline in carcinogen injected rats fed wheat bran diets,
while in saline rats there was no difference in intracellular
pH between diets. Thus, reduction of intracellular pH,
presumably by the presence of increased SCFA was not
protective. Finally, neither diet nor carcinogen treatment
had a significant effect on cell cycle position (e.g.
percentage of S phase cells) or apoptosis. In conclusion,
these data show that while diets containing wheat bran fiber
bran fiber are not, it is not luminal butyrate concentrations
that are of primary importance to this effect.
Issued also on microfiche from University Microfilms Inc.
Includes bibliographical references: pages 149-180.