There is a certain cachet in the term "American doctor," much as there is in "Swiss banker," "French chef," or "Soviet dissident." Hardly a month goes by without a team of U.S. physicians flying off to perform delicate surgery on some ailing international celebrity. The Nobel Prize in medicine has long been dominated by Americans. A large share of the science news chronicles the achievements of our physicians. There is nothing wrong with such eminence. But...