Abstract: Radiolabelled polypeptides derived from the Viperidae disintegrins are provided as well as a method for the detection of venous and arterial thrombi, pulmonary emboli and tumors or abscesses that have a thrombus component. Compositions suitable for parenteral administration comprising the radiolabelled polypeptides and a pharmaceutically acceptable carrier are also provided.

Abstract: Thrombolytic hybrids are formed as covalent or non-covalent complexes of fibrin fragments and plasminogen activator molecules. Native plasmin degradation fragments of fibrin or non-native fibrin fragments are covalently or non-covalently linked to plasminogen activators such as t-PA, scu-PA, urokinase, streptokinase, and the like. Useful native fibrin fragments which may be utilized to form complexes with plasminogen activators include fragments E.sub.1, E.sub.2, E.sub.3, D and DD, and (DD)E complex. The fibrin fragment component targets the hybrid to vascular thrombi, immobilizing the plasminogen activator molecule onto the fibrin surface of the thrombus. Once localized on a thrombus surface, the plasminogen activator component of the hybrid activates only the clot-surface bound plasminogen transported by the fibrin fragment vehicle, without significant systemic activation of plasminogen.

Abstract: Nuclear magnetic resonance imaging of animal or human tissue is enhanced when a paramagnetic pyrophosphate compound is administered intraveneously as a contrast agent. The contrast agent is particularly useful in magnetic resonance imaging of area of tissue calcification, such as acute myocardial infarctions. Specific localization of paramagnetic pyrophosphate in ischemic and necrotic muscle cells at the periphery of a myocardial infarction makes accurate localization and sizing of the central infarct and peri-infarct zones possible.

Abstract: A method of locating thrombi in vivo comprising the steps of administering a radiolabeled peptide selected from the group consisting of Fragment E.sub.1 isolated from cross-linked fibrin, Fragment E.sub.2 isolated from crosslinked fibrin, and peptides having an amino acid sequence intermediate between Fragments E.sub.1 and E.sub.2 derived from crosslinked fibrin by plasmin digestion to a human or animal wherein the peptide is selectively incorporated or bound by forming a pre-formed thrombi and externally detecting the radiation emitted by the radiolabeled peptide. A composition containing the peptide used for locating thrombi is also disclosed.