Browsing by Author "Martins, Paulo N."

Now showing 1 - 2 of 2

Impact of Donor and Recipient Age on Allograft Tolerance
(Başkent Üniversitesi, 2009-06) Martins, Paulo N.
The elderly represent the fastest growing segment of the population with end-stage organ disease and the use of aged grafts increased exponentially. Since aging of the immune system, or "immunosenscence" is generally associated with weaker immune responses, one might expect the elderly to be less reactive against transplanted organs than younger patients and therefore to show better results in terms of transplant outcome. Paradoxically, however, experimental studies and clinical data of organ transplantation show that old age of either the recipient or the donor is associated with poorer outcomes. On the other hand transplant tolerance is easier to be induced in the neonatal period. One potential reason for this discrepancy may lie in the effects of immunosenescence on the induction of tolerance. While the impact of aging on acute and chronic allograft rejection has been extensively studied, its role on establishing transplant tolerance is not well known. Since tolerance is an active process, and not just the absence of an immune response, the immunologic changes associated with the aging process may interfere with graft survival. In experimental and clinical transplantation, most successful tolerance induction protocols have been tested on young individuals, using grafts from young donors. However, some experiments that have utilized aged animals have demonstrated resistance to tolerance induction. Extrapolation of these results to humans suggests that protocols for clinical tolerance induction may not be effective in the elderly and may need to be revised for this population. The resistance to achieving immunological tolerance with aging is complex and multifactorial. Here, we review the age associated changes that may interfere with immunologic tolerance. Understanding this phenomenon may help in developing novel therapeutic approaches to reverse the crucial dysfunctions of the aging immune system and achieve effective tolerance regimens for the elderly.
Massive Pulmonary and Intracardiac Embolism During Liver Transplantation
(Başkent Üniversitesi, 2010-06) Sheiner, Patricia; Martins, Paulo N.; Kim-Schluger, Leona; Rodriguez-Davalos, Manuel; Martins, Ann-Britt; Krachkova, Nathalia; Facciuto, Marcelo
Despite prolonged coagulation times and thrombocytopenia associated with end-stage liver disease, formation of thrombi in the circulation seems to occur more frequently during liver transplant than during any other type of major surgery. Here, we report a case of massive pulmonary and intracardiac embolism that resulted in cardiac arrest and intraoperative death. This was diagnosed by transesophageal echocardiography and occurred shortly after induction of anesthesia and initiation of continuous veno-venous hemofiltration without the concomitant use of antifibrinolytic drugs. We discuss the physiologic changes associated with cirrhosis and liver transplant, and review the literature.