Clinical correlation of serum amine levels, with varying clinical protocols of collaborating investigators in order to evaluate toxicity of the amines. Intubation of patients with progressive renal failure to detect dissociation of abnormal bacterial flora and amine levels in small intestine. End stage uremia patients will be treated withh antibiotics to reduce amine levels. In vitro growth of small intestinal organisms from uremic patients and demonstration of generation of toxic amines; with feeding of specific amine formers to germ free rats. Amine metabolism will then be restudied after monocontamination has been eliminated following gut sterilization. Define metabolic relationship between TMA and TMA-oxide.