MAGNETIC MICROCAPSULE EXPLORATION IN THE GASTROINTESTINAL CAVITY OF THE ORIGINS OF COLORECTAL CANCER-ASSOCIATED DNA-DAMAGING AGENTS IN THE HUMAN DIET

Magnetically recoverable, semipermeable microcapsules have been devise d for covalent entrapment of reactive substances in the intestinal cav ity to biomonitor potentially DNA-damaging agents and the effects of e tiologically important components of the human diet. These microcapsul es have been shown to trap five types of agents in vivo, namely, carci nogen electrophiles, nitrosating agents, mutagens/carcinogens having a planar molecular structure, and as-yet unidentified endogenous cross- linking agents and precursors of reactive oxygen species. Substantial alterations in both total metabolites and types of metabolites trapped from [C-14]benzo(a)pyrene were found to be caused by increasing (with in the human intake range) the dietary levels of beef protein and diet ary fiber. The system thus responds to a variety of potentially critic al agents and in a manner consistent with epidemiologically important dietary modulators for colorectal carcinogenesis. Work toward recogniz ing entrapped endogenous agents has also begun.