1.   The rat experiments that we have been considering suggest that the interference theory is more accurate.

2.   The female hormone estrogen someday could be used to prevent or treat stroke, if beneficial effects seen in rat experiments can be duplicated in humans.

3.   As far as can be told from rat experiments, it is safe and carries no side effects.

4.   But two weeks ago, it suspended human testing of the drug after rat experiments turned up possible kidney damage.