Former First Lady Barbara Bush remains hospitalized for the fourth day, as doctors puzzle over her mysterious illness. After a week of sickness, Bush, 84, has gone through many tests, but doctors haven't figured out what's wrong. "She is in no pain, so there is no rush" to release her, a family spokesman said, and did not release details other than that the disease is not life-threatening. Her husband, former President George H. W. Bush, has been by her side in the Houston hospital every day. A little more than a year ago, Barbara had precautionary open-heart surgery and recovered "extremely well." Two years ago, she had surgery for an ulcer, and in 1989, she lost 18 pounds in three months due to Graves disease, a thyroid condition, and began taking steroids to treat the condition. Bush received radiation treatment on her eyes in 1990.