The purpose of the research is to study a common and dangerous medical condition called 'septic shock' that often occurs in critically ill patients. In order to learn about septic shock in humans, we will administer a substance called 'endotoxin' to participants in this study. Endotoxin causes a temporary period of inflammation in the human body, a brief 'virtual' infection. This is an established method for the investigation of inflammation properties. We are interested in how the natural hormone, cortisol, can affect the human response to endotoxin. We know that when cortisol is given at the same time as endotoxin it can decrease the inflammation that occurs due to endotoxin. In this study we will test whether or not cortisol, when given the day before the endotoxin, will work to change the inflammation that occurs due to endotoxin. In order to test this, two-thirds of the study participants will receive cortisol on the day before they receive the endotoxin and one-third of the study participants will receive a placebo (no medication) before the endotoxin.