The Medical (Udioisotopes Research Program is investigating methods that will allow us to label molecules, which can then be used to image, diagnose, and treat various diseases. The two major components of this project are to develop labeling chemistry and to study targeting techniques. Articles relate*! to this research can be round in Sees. 4 and I Oof this report Right: We use cell-culture techniques to evaluate the ability oflymph nodes (red medium) and tumor cells (orange medium) to concentrate various radiopharmaceuticals.Below: The gamma-camera terminal displays the uptake of a radiophamaceutical in tissue. In this example, color gradation corresponds to the concentration of radiopharmaceutical (white > red > yellow > blue) in the heart.Above: We usa computer modeling to design specific chelating agents (metal-binding molecules); these structures are easily examined on the terminal. In this model, nitrogen atoms (blue) are the binding sites and are held in rigid conformation by carbon atoms (green); hydrogen atoms are shown in white. --/ , --J-)tope to specific tumor sites. .""." chromotograplw is used to separate the orange metalated porphyrin that contains Lu from the green unmetalated form.Front Cover: This photo is a gamma-camera image; the subject, an anesthetized rat, had been injected with a compound to which a radioisotope had been attached, or "labeled." In the initial steps of this experiment, the front paws of the rat had been injected with a chemical that caused an inflammation. The 67 Cu-labeled porphyrin ""•; theqjnjected. The majority of the labeled porphyrin is localized le jjfontJjws^pm^^tSjty is also evident in the liver. (Blue cafes tirearejSjjJf TOftflit concentration of radiopharmaceutical, ana yefaft wdicBwrrwcftsrate concentration, and green areas have the least concentration.