Stent-graft use in urgent and emergent AAA management.

The use of stent grafts in the treatment of ruptured aortic aneurysm, abdominal (AAA) may reduce mortality associated with this process through its dramatic alteration of the surgical technique employed. Advantages of endovascular repair include the ability to perform the procedure under local anesthesia, decreased physiologic stress of avoiding a laparotomy and avoiding collateral damage during open repair. Criticisms of this technique include additional preoperative time spent obtaining appropriate imaging, the necessity for specialized products and personnel required to perform the procedure, and late complications such as abdominal compartment syndrome. Current data regarding a survival advantage appear favorable but flawed, highlighting the need for prospective randomized trial. Three trials are currently underway with the largest, the IMPROVE trial, the most likely to yield definitive evidence.

Comparison of activation requirements and activation phenotype of allogeneic and xenogeneic rodent responses in vivo and in vitro.

BACKGROUND: Both discordant and concordant xenogeneic responses are dominated by humoral immunity. Recent advances in molecular engineering approaches may largely prevent rejection by means of this pathway, leaving the cellular arm of the immune response as the principal remaining barrier to successful engraftment. METHODS: To characterize further the cellular response to xenogeneic tissues, we used the intracellular fluorescent marker CFSE (5-(and-6)-carboxyfluorescein diacetate succinimidyl ester) to track the mitotic record of T cells (and T cell subsets) after either xenogeneic or allogeneic activation in vitro or in vivo. Activation marker expression was monitored by simultaneous labeling with antibodies for either CD25 or CD134. RESULTS: The in vitro and in vivo responses of Lewis lymphocytes were generally similar in magnitude and timing comparing activation with allogeneic or xenogeneic stimulators. However, the xenogeneic T cell precursor frequency was found to be markedly higher than that previously reported and were comparable to that seen in allogeneic responses. Xenogeneic responses were unique in the continued expression of activation markers in later division cycles. In addition, CD4 and CD8 T-cell proliferation was highly dependent on stimulator class II expression, highlighting the importance of CD4 T cells and the indirect pathway in the xenogeneic response. CONCLUSIONS: An unexpectedly high precursor frequency was detected for xenogeneic cellular responses in the rat anti-mouse combination and was comparable to that seen in allogeneic responses. Differences in xenogeneic versus allogeneic activation profiles exist that may result from the cellular pathways used for activation.