(Portland, OR)  --  One of the most popular animals at the Oregon Zoo is dead after being euthanized.  The Indian elephant named Rama was put to sleep after veterinarians determined that pain and mobility problems related to a 25-year-old leg injury were too much for him to bear any longer.  Zoo officials say Rama was diagnosed in 2013 with tuberculosis, but the disease wasn't a factor leading up to his being put down.