 2. Women of childbearing potential who are pregnant, breast feeding, or unwilling to avoid pregnancy i.e., the use of appropriate contraception including oral and subcutaneous implantable hormonal contraceptives, condoms, diaphragm, intrauterine device IUD, or abstinence from sexual intercourse Note: Prospective female participants of childbearing potential must have negative pregnancy test urine within 48 hours prior to study entry. 