Sergio Olaya, an employee of the U.S. Senate, struggled quietly, until Saturday's Times anyway, to keep himself together while under the yoke of a $255,000 medical bill incurred by his dying mother. He's one of the 44 million of us who have no health insurance. So senators come and go all day, passing this fellow, themselves very well insured, having 5 Senate doctors and a team of 14 nurses on call. Only one senator, Sherrod Brown of Ohio, has refused the insurance, insisting that all Americans should be covered first. Here's the piece: JUST OFF THE INSULAR SENATE FLOOR . . .