The Wall Street Journal Market Watch  Aug. 8, 2011, 11:30 a.m. EDT By Peter Loftus The U.S. Justice Department has issued a subpoena to Merck & Co. MRK +0.97% as part of a criminal investigation into the marketing of certain drugs, Merck said Monday. The drugs are Temodar, which treats brain tumors; hepatitis C treatment […]