WASHINGTON, Aug 23 (Reuters) – The U.S. National Institutes of Health revised on Tuesday its 16-year-old conflict of interest rules for medical researchers, lowering the amount of money that constitutes a financial conflict and expanding the required disclosures….Concern about the integrity of research in the United States has grown since 2008, when Iowa Republican Sen. Charles Grassley criticized prominent Harvard University psychiatrist Dr. Joseph Biederman and others for failing to fully disclose payments from drug companies.