By THE ASSOCIATED PRESS BOSTON (AP) -- The makers of Tysabri, a new drug used to treat multiple sclerosis, announced Monday they are voluntarily suspending sales of the drug after one patient died and another developed a serious disease of the central nervous system.Stocks of both Biogen Idec Inc. and Elan Corp. tumbled, while shares of ther makers of rival MS drugs rose.The biotechnology companies said in a news release that they have suspended supplying and marketing the drug Tysabri and advised doctors to suspend prescribing the medication. The companies also have stopped using the drug in clinical trials.The companies...