Maintenance of patency after vascular trauma by topical irrigation with a peptide homologous to the carboxy-terminus of the fibrinogen gamma chain.

Synthetic peptides with amino acid sequences homologous to the carboxy-terminal sequence of the gamma chain of human fibrinogen were evaluated for their capacity to inhibit thrombus development. A 21-residue peptide effectively inhibited surface-mediated fibrin clot propagation in vitro. Since this effect was localized to the surface, we proceeded with in vivo evaluation, using site-specific topical application only. In a rat model of arterial trauma and microvascular repair, topical application of the 21-residue peptide significantly reduced the rate of thrombosis to 17%, as compared with a control rate of 83%; in comparison, a 12-residue homologue reduced the thrombosis rate only modestly to 61%, which was not significant compared with the control rate. These results indicate the feasibility of antithrombotic therapy with topically applied agents, an approach that may obviate the use of systemic anticoagulation in extremity-replantation surgery.

Experimental study of the influence of arterial trauma on dependent distal tissue survival.

An experimental model was developed combining arterial trauma with island flap creation using the rat groin flap system. Flap arteries were subjected to crush/avulsion injuries with subsequent microvascular repair. A second series involved resection 4 hr after thrombosis of injured flap arteries and interpositional vein grafting to reestablish circulation. A single bolus of systemic heparin was administered to half of the animals from each series on a blinded, randomized basis. Arterial patency at 7 days correlated with flap survival. There was no case of partial flap loss. Patencies improved in the first series from 31% to 71% with heparin administration (P less than 0.05) and from 58% to 90% in the second (not significantly different). A third series involving immediate resection of traumatized vessel and vein graft replacement achieved a patency of 92% (without heparinization). These results support the value of replacement of all traumatized arterial tissue with vein grafts and indicate the efficacy of systemic heparin (in single bolus) for enhancing the likelihood of maintaining patency. Furthermore, it is suggested that the occurrence of a thrombogenic site in the arterial inflow to a region of dependent tissue does not lead to partial tissue loss, and thus thromboembolic events may not be responsible for this clinical phenomenon.

MR imaging of osteochondral lesions of talus.

Ten patients with osteochondral lesions of the talus had magnetic resonance (MR) imaging to determine if this modality could accurately characterize the bone lesion and overlying articular cartilage. Eight patients had arthroscopy, five of whom also had arthrotomy. Magnetic resonance detected abnormal cartilage in all eight patients and disruption of cartilage in four of five, proven at surgery. One patient had disrupted cartilage at surgery not diagnosed by MR. Four patients had excision of the osteochondral fragment and curettage of the talar defect and in these patients MR accurately characterized the bony lesion. Three patients had conservative surgical procedures (drilling) and the extent of the bony lesion could not be determined at surgery. Magnetic resonance can accurately characterize the osteocartilaginous components of talus lesions and even though it should not replace plain radiography for diagnosis, it is ideally suited for evaluation of the articular cartilage and has proven to be useful in planning surgical procedures.

The long-term fate of fresh and frozen orthotopic bone allografts in genetically defined rats.

Fresh and frozen orthotopic iliac crest bone grafts in rats were studied histologically for determination of the long-term effects of histocompatibility matching and the freezing process on orthotopic bone graft incorporation. Grafts exchanged between groups of inbred rats, syngeneic or differing with respect to major or minor histocompatibility loci, were studied histologically at 20, 30, 40, 50, and 150 days after bone transplantation. A numerical histologic scoring system was developed and used by three observers for evaluation of coded hematoxylin and eosin sections. All frozen graft groups had the same fate regardless of histocompatibility relations between donors and recipients, and all grafts were inferior to fresh syngeneic grafts. Both fresh allograft groups received similar scores and initially at 20 and 30 days had scores similar to those of the fresh syngeneic groups. In the later intervals, however, the fresh allografts were inferior to the fresh syngeneic grafts and similar to the frozen groups. This is consistent with an older model describing two distinct phases of osteogenesis. In the long term, frozen syngeneic and fresh and frozen allografts across major and minor histocompatibility barriers were comparable, but all were significantly inferior to fresh syngeneic bone grafts.