Recoverable, semipermeable, microencapsulated DNA surrogates for monitoring the colorectal cavity; in-situ effects of fibre and meat in human diets on benzo[a]pyrene and possible endogenous cross-linking agents.

Semipermeable magnetic microcapsules containing polyethyleneimine (PEI) as a DNA surrogate are shown to trap 14C-benzo[a]pyrene and hitherto unknown, endogenous, putative cross-linking agent(s) within the gut of male Fischer rats. Trapping is substantially modulated by complete, cooked human diets fed isocalorically and varied three-fold in either beef, fat or bran fibre nonstarch polysaccharide within the normal human intake levels. Preliminary results indicate that the crosslinking agent(s) are derived from microflora. Using metabolized benzo[a]pyrene as a model DNA damaging agent within the gut, beef and decreased bran fibre were found to increase its availability, paralleling risk alterations found in nutritional epidemiology. These novel microcapsules are capable of intercepting a range of substances relevant to DNA damage.