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Publications (2)7.79 Total impact

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    ABSTRACT: Oxidant injury occurs when an organ is severed from its native blood supply and then reperfused and continues during subsequent periods of immune attack. Experiments here test the hypothesis that an antioxidant given only in the peri-reperfusion period protects against not only oxidative but also nitrosative stress, leading to reduced vasculopathy long after cardiac allotransplantation. Experiments were performed using a murine heterotopic cardiac transplantation model. An antioxidant, in the form of intraperitoneal high-dose riboflavin, was given to recipients during the initial 3 days after transplantation. Antioxidant-treated mice showed significantly longer graft survival than control mice. At 4 h after transplantation, antioxidant treatment significantly reduced graft lipid peroxidation and oxidized DNA and preserved antioxidant enzyme activity. At day 6 posttransplantation, the redox-sensitive transcription factor nuclear factor-kappaB and inducible nitric oxide synthase were significantly reduced following antioxidant treatment, with concomitant reduction of nitrotyrosine. Despite the limited duration of antioxidant treatment, both acute and chronic rejection were significantly suppressed. In vitro experiments confirmed suppression of nitrosative and oxidative stress and cardiomyocyte damage in antioxidant-treated cardiac allografts. Collectively, antioxidant administration during the initial 3 days after transplantation significantly reduces nitrosative and oxidative stress in cardiac allografts, modulates immune responses, and protects against vasculopathy.
    AJP Heart and Circulatory Physiology 02/2009; 296(4):H1007-16. DOI:10.1152/ajpheart.00498.2008 · 4.01 Impact Factor
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    ABSTRACT: Riboflavin is a well-known nutritional supplement that has been shown to exhibit antioxidant properties and protect tissue from oxidative damage. We hypothesized that riboflavin given during cardiac ischemia-reperfusion (I/R) might reduce subsequent acute rejection, after allotransplantation, and coronary allograft vasculopathy (CAV). A murine heterotopic cardiac transplantation model was used to test whether riboflavin improves I/R injury and acute/chronic rejection. Riboflavin significantly reduced oxidant production and inflammatory mediator production induced by I/R injury, as evidenced by decreased levels of malondialdehyde, myeloperoxidase activity, and tumor necrosis factor alpha. Administration of riboflavin also improved graft survival and suppressed T-cell infiltration and donor-reactive alloantibody formation during the early period after allotransplantation. A murine long-term cardiac allograft model using immunosuppression (preoperative anti-murine CD4 and anti-CD8) was employed to investigate the effect of riboflavin against CAV at 60 days. Riboflavin-treated grafts exhibited a significant decrease in the severity of coronary artery luminal occlusion as compared with saline-treated grafts (17.4+/-1.8% vs. 43.5+/-5.6%, P=0.0012). However, there was no significant effect of riboflavin to reduce donor-reactive alloantibodies in this chronic model. These data indicate that riboflavin improves early I/R injury and reduces the development of CAV, most likely due to alloantigen-independent effects such as reduced early graft oxidant stress. Riboflavin administered in the setting of cardiac allograft transplantation appears to be a powerful means to reduce early graft lipid peroxidation, leukocytic infiltration, and cytokine production as well as to suppress the late development of cardiac allograft vasculopathy.
    Transplantation 04/2007; 83(6):747-53. DOI:10.1097/ · 3.78 Impact Factor