<qa>  What is the goal of the investigators?The investigators overall goals are i to determine the relationship between serum and prostate tissue hormone concentrations in men in response to increasing doses of exogenous androgens; ii to determine the impact that alterations in serum and tissue testosterone concentrations have on prostate epithelial cell function and phenotype; and iii to determine the relationships between prostatic androgens and alterations in the tissue microenvironment. The investigators will perform a study in healthy, middle-aged men to address the following Specific Aims: 