This project seeks to improve radioisotopic methods of diagnosis of several renal diseases by several means: (1) synthesis of new radioactive agents by coupling bifunctional chelates to compounds known to be extracted with high efficiency by the renal tubules, and to low molecular weight proteins extracted and catabolized by the kidneys.  The chelating groups will permit labeling of the compounds, with 99mTc with high yield and stability, (2) development of lipsomes containing 131I-Hippuran, 125I-iothalamate or 111In-DTPA suitable for intramuscular injection, enabling simultaneous measurement of glomerular filtration rate and effective renal plasma flow by standard clearance technics, (3) trial of reinjection of autologous neutrophils labeled with 99mTc or 111In-oxine for the detection of active renal infection associated with chronic pyelonephritis by scintillation camera imaging in experimental dogs and later in selected patients, (4) trial of neutrophils and platelets labeled with 99mTc or 111In-oxine for the early diagnosis of acute cellular rejection of renal allografts in dogs, and later in human transplants, (5) improvement of renal functional information derived from continuous imaging with a scintillation camera following the injection of renal radiopharmaceuticals by digital computer processing, using special "background subtraction" and "liver subtraction" technics.