The owner of two research hospitals affiliated with the Harvard Medical School has imposed restrictions on outside pay for two dozen senior officials who also sit on the boards of pharmaceutical or biotechnology companies. The rules, which became effective Jan. 1, impose limits specifically on outside directors who guide some of the nation’s biggest companies. Medical experts say they believe the conflict-of-interest rules at the institution, Partners HealthCare, go further than those of any other academic medical center in restricting outside pay from drug companies, the New York Times reports.