7. Coagulation: Patients must have adequate hemostatic function defined as PT and PTT less than or equal to 1.5 times ULN. Patients receiving prophylactic anticoagulation for thrombosis are eligible if they meet criteria for adequate hemostatic function (PT and PTT less than or equal to 1.5 times ULN) and thrombotic episode occurred 3 months prior to enrollment. Use of anticoagulants or thrombolytics for care and maintenance of central venous catheters is acceptable.