Tensile strength of surgical knots in abdominal wound closure.

Abdominal wound dehiscence is a surgical catastrophe that can be attributed to patients or technical factors. The technical properties of the monofilament sutures and knots that are commonly used in abdominal closure are poorly understood. The aim of this study was to compare the tensile strength of monofilament sutures tied with conventional knots. To do this, the knot-holding capacity of four types of knots (square, surgeons', Aberdeen and loop) were tested using three types of gauge 1 monofilament suture, namely nylon, polyglyconate and polydioxanone, using a tensiometer. We found that the knot-holding capacity of the loop knot was between twofold and threefold greater than all the other knots examined. In comparing suture types, polyglyconate had the highest knot-holding capacity for all the knots that were examined and there was no difference in the tensile strength of nylon and polyglyconate tied in a square, surgeons' or Aberdeen knot (P < 0.05). In conclusion, our findings suggest that closure of an abdominal wound would be best commenced with a loop knot, using gauge 1 polyglyconate and finished with either an Aberdeen square or surgeons' knot would be appropriate.

Intragraft gene and protein expression in rat liver allografts treated with costimulatory blockade alone or in combination with CyA.

BACKGROUND: Costimulatory blockade has been shown to prevent acute rejection (AR) and promote long-term graft survival in a number of animal models including nonhuman primates. The effect of concomitant administration of conventional immunosuppressives on long-term liver allograft survival and intragraft expression of immune mediators has not previously been examined. MATERIALS AND METHODS: A high-responding Dark Agouti to Lewis orthotopic liver transplant (LEW OLT) model was used to compare anti-CD154 alone, or in combination with cyclosporin (CyA) on allograft survival. Donor-specific reactivity was assessed by mixed lymphocyte reaction (MLR) and allogeneic skin grafts. Surviving rats were euthanized on day 150 and intragraft gene (CD80, 86, 152, 154, IFN-gamma, IL-2, IL-6, IL-10, IL-13, TNF-alpha, TGF-beta, IL-7, Fas-ligand, Granzyme B, bax, and bcl(2)) and protein (CD4, CD8, ED1, CD154, CD80, CD86) expression was measured. RESULTS: Untreated control recipients had a median survival time of 5 days. Recipients treated with anti-CD154 survived to beyond 150 days with no evidence of AR. Concomitant administration of CyA did not alter the long-term survival. There was no difference in the serum aspartate aminotransferase between treatment groups or a change over time. All treated recipients showed a reduction in donor-specific MLR at day 40 and 60 but had persistence of donor reactivity to skin grafts at day 100. Histologically, liver architecture was well preserved despite the presence of a nondestructive mononuclear cell infiltrate. Analysis of intragraft gene expression revealed an inverse relationship between the duration of anti-CD154 therapy and the gene expression of costimulatory molecules and Th1 cytokine transcripts. The pro-apoptotic gene, bax, was increased in recipients treated with anti-CD154, but not CyA, compared with normal liver. CONCLUSIONS: These data demonstrate that anti-CD154 therapy either alone or in combination with CyA allows for the long-term survival of liver allografts in the rat despite there being a difference in the intragraft gene and protein profile.

Analysis of intragraft gene and protein expression of the costimulatory molecules, CD80, CD86 and CD154, in orthotopic liver transplant recipients.

CD40-CD154 and/or CD28-CD80/86 costimulatory blockade induces long-term allograft survival in numerous animal models. Studies examining the expression of costimulatory molecules during acute cellular rejection (ACR) have been limited to renal and cardiac allografts. The aim of this study was to describe the relationship between intragraft costimulatory molecule expression in OLT recipients and ACR. Forty-five liver biopsies were obtained at reperfusion and day 7. Gene and protein expression of CD80, CD86 and CD154 were analyzed by RT-PCR and immunohistochemistry. CD154 protein expression was present in 13 of 18 patients with a RAI score of 4, but in only two of 14 patients with a RAI score of <4. There was a strong association between the RAI score and the presence of CD80 and CD154 immunoreactivity. CD86 protein expression did not correlate with the severity of ACR. In reperfusion biopsies CD154, but not CD80 or CD86, protein expression correlated with the total ischaemic time. There was no association between expression of costimulatory molecule genes and ACR. In conclusion, we have demonstrated an association between CD154 and CD80 protein expression and ACR in orthotopic liver allografts.