11.   The liver works to rid the body of foreign substances.

12.   The researchers found that applying various foreign substances to ant routes did have some effect in reducing ant populations during unusually heavy invasions.

13.   These cells are sensitized by the foreign substance and later release another class of chemicals, called lymphokines, that cause an inflammatory reaction.

14.   This month, state legislatures in Ohio and Oklahoma are debating legislation that would toughen penalties for animal exhibitors who pump up animals with drugs or other foreign substances.

15.   Walker was a native of Nashville, Tenn., so he surely was regarded as a foreign substance by most Nicaraguans.

16.   Was there any contact with a foreign substance?

17.   Why the jump in recalls of drugs containing foreign substances?

18.   A gene called GMF-CSF, which produces a protein that alerts tissues to the presence of foreign substances, was inserted into the cancer cells.

19.   Antibodies are proteins the body produces to destroy foreign substances.

20.   Because it so closely resembles bone, researchers said, the body does not reject the cement and react as it does to most foreign substances.