Screening Visits. All procedures and risks associated with the study will be explained to the volunteer while obtaining informed consent. To determine eligibility for participation, all subjects will be screened with a battery of tests, including: 1) a physical examination and medical history (including history of asthma); 2) blood tests (25 ml blood), including cell count and liver function, hepatitis B and C, HIV, cholesterol, and electrolytes; coagulation panel; Urea Nitrogen (BUN), creatinine 3) urinalysis for kidney function; 4) an electrocardiogram (ECG); 5) an oral glucose tolerance test (OGTT) and 6) a 2D echo with agitated saline.