Patent ID: 7541157

Claim:
A method of screening molecules, comprising: (1) administering to at least one animal molecules, wherein the molecules have the following general formula: propyl-NH-Yaa-(R,S)Phe(PO 2 —CH 2 )(R,S)Leu-Yaa′-NH 2 , wherein each of Yaa and Yaa′ represents a natural amino acid, in which each molecule is pre-labeled with a radioactive isotope capable of being detected, (2) sacrificing at least one of the animals and analyzing in vivo the distribution within tissues or organs of said at least one animal of the radioactivity of the molecules administered by analyzing sections of tissues or organs from which samples have been taken with an imaging devices capable of detecting said radioactive isotope, (3) selecting sections of tissues or organs in which a radioactive signal is detected, (4) isolating from said sections of tissues or organs, selected in step (3), radioactive fractions, and (5) identifying a molecule from the administered molecules, using the radioactive fractions obtained in step (4), distributed in a particular tissue and/or organ.