Niacin is a vitamin that has beneficial effects on cholesterol (a type of fat in the blood) when used in high doses. Different people respond differently to cholesterol lowering doses of niacin, some people have a side effect termed flushing (similar to a hot flash) while others do not and some people have more pronounced effects on cholesterol. Endotoxin or lipopolysaccharide (LPS) is a small part of bacteria (that is no longer living) that can cause many of the effects similar to bacterial infections in humans. However, it can be administered in very small amounts to produce a mild inflammatory response much the same as a 'flu-like" illness. Within 1 ½ -3 hours after giving LPS by vein, a response consisting of fever, chills, headache, nausea and vomiting and generalized aches and pains will occur which lasts up to 6-8 hours. In addition to the flu like symptoms, the inflammation causes changes in cholesterol, triglycerides and glucose clearance. Different people respond differently to endotoxin and inflammation. We are performing this study to see if there are genetic factors that predict how people will respond to niacin and to endotoxin and its inflammatory response.