title: Proteolysis of von Willebrand factor after thrombolytic therapy in patients with acute myocardial infarction.
abstract: In 20 patients with acute myocardial infarction (AMI) treated with streptokinase (SK, n = 7), recombinant single-chain tissue plasminogen activator (rt-PA, n = 7) or urokinase (UK, n = 6), the behavior of plasma von Willebrand factor (vWF) was studied before and 1.5, 3, 24, 48, and 72 hours after beginning thrombolytic therapy. vWF antigen (vWF:Ag) was high in plasma, especially after SK. The ristocetin cofactor (RiCof) activity of vWF, high before therapy, tended to decrease soon after therapy. This pattern of vWF changes was paralleled by the early loss of higher molecular weight multimers. By immunoblotting of immunopurified and reduced vWF and monoclonal antibody epitope mapping, we found that vWF was degraded after thrombolysis, especially after SK, as indicated by the higher values of two plasmin-generated fragments of 176 and 145 Kd. There were more plasmin-generated fragments in the five patients who had bleeding complications than in the remaining 15 who did not. In conclusion, quantitative and qualitative changes of vWF compatible with proteolytic degradation of the protein occur during thrombolytic therapy. Such degradation, roughly proportional to the degree of the general lytic state induced by each agent, might be a cofactor of the bleeding complications occurring in treated patients.
authors.affiliation: Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, IRCCS Maggiore Hospital, Milano, Italy.
authors.forename: A B
authors.initials: AB
authors.lastname: Federici
authors.forename: S D
authors.initials: SD
authors.lastname: Berkowitz
authors.forename: T S
authors.initials: TS
authors.lastname: Zimmerman
authors.forename: P M
authors.initials: PM
authors.lastname: Mannucci
mesh_terms: D005341:Fibrinolysin / Q000378:metabolism; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D015151:Immunoblotting; D009203:Myocardial Infarction / Q000097:blood / Q000188:drug therapy*; D010446:Peptide Fragments / Q000097:blood; D011994:Recombinant Proteins / Q000009:adverse effects / Q000627:therapeutic use; D012310:Ristocetin / Q000378:metabolism; D013300:Streptokinase / Q000009:adverse effects / Q000627:therapeutic use; D015912:Thrombolytic Therapy / Q000009:adverse effects*; D010959:Tissue Plasminogen Activator / Q000009:adverse effects / Q000627:therapeutic use; D014568:Urokinase-Type Plasminogen Activator / Q000009:adverse effects / Q000627:therapeutic use; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D011994:Recombinant Proteins; D014841:von Willebrand Factor; D012310:Ristocetin; D013300:Streptokinase; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator