Showing papers by "Ralph S. Greco published in 1989"

Binding of tissue plasminogen activator to vascular grafts.

Abstract: Tissue plasminogen activator labeled with radioactive iodine (125I-tPA) was immobilized on vascular prostheses chemically modified with a thin coating of water-insoluble surfactant, tridodecylmethylammonium chloride (TDMAC). Surfactant-treated Dacron, polytetrafluoroethylene (PTFE), silastic, polyethylene and polyurethane bound appreciable amounts of 125I-tPA (5-30 micrograms 125I-tPA/cm2). Upon exposure to human plasma, the amount of 125I-tPA bound to the surface shows an initial drop during the first hour of incubation, followed by a slower, roughly exponential release with a t 1/2 of approximately 75 hours. Prostheses containing bound tPA show fibrinolytic activity as measured both by lysis of clots formed in vitro, and by hydrolysis of a synthetic polypeptide substrate. Prior to incubation in plasma, tPA bound to a polymer surface has an enzymic activity similar, if not identical to that of the native enzyme in buffered solution. However, exposure to plasma causes a decrease in the fibrinolytic activity of both bound tPA and enzyme released from the surface of the polymer. These data demonstrate that surfactant-treated prostheses can bind tPA, and that these chemically modified devices can act as a slow-release drug delivery system with the potential for reducing prosthesis-induced thromboembolism.

The effect of viable omentum on early bile leakage and healing of liver lacerations.

Abstract: In order to determine if omental tissue accelerates the healing of liver lacerations, simulated bile leakage and collagen biosynthesis were studied in 53 rabbits. After creating a standardized complex liver laceration, hemostasis was obtained by vessel ligation and electrocoagulation. The wound was either left open (OP) or viable omentum sutured to its base (OM). Simulated bile leakage was noted in all of eight animals (four OM, four OP) studied on day of injury. None of 18 OM and two of 17 OP animals demonstrated extravasation of dye from the wound on the second and third postinjury day (N.S.). The ratio of mRNA for alpha 1(I) procollagen/actin, used as an indicator of wound healing, was 56.3 +/- 7.8 for OM and 50.6 +/- 12.1 for OP at the wound edge, and 63.5 +/- 18.6 and 69.2 +/- 7.5, respectively, for RNA isolated from the scar (N.S.). For alpha 1(III) procollagen mRNA, the ratio was 23.9 +/- 3.5 for OM and 22.4 +/- 8.3 for OP at the wound edge, and 32.4 +/- 6.5 and 31.8 +/- 7.9, respectively, for RNA isolated from the scar (N.S.). There was no difference in the scar hydroxyproline content between the two repair methods. In this model of hepatic injury and repair, bile leakage was minimal by the second postinjury day with both repair methods. Placing the omentum in liver lacerations did not contribute to accelerated wound healing as measured by simulated bile leakage and collagen biosynthesis.

A simplified approach to techniques of splenic salvage.

Abstract: Splenic salvage or partial splenectomy may be simplified by following these basic steps. The spleen is completely mobilized from all of its attachments so that it is tethered only by its blood supply. Appropriate hilar and short gastric vessels are ligated, and devitalized splenic tissue is debrided. Parenchymal bleeding is controlled by compression using horizontal mattress sutures placed through pledgets of folded sheets of oxidized cellulose.