Although smoking cessation is a prerequisite prior to listing for cardiac transplantation, some patients return to smoking after recovery. We have covertly assessed the smoking habits of our cardiac transplant recipients (with ethical approval) since 1993 by measuring urinary cotinine: a level of >500 ng/mL signifying continued tobacco use. We retrospectively analyzed survival, causes of death and the development of graft coronary artery disease (GCAD) with respect to the number of positive and negative cotinine levels. One hundred four of 380 (27.4%) patients tested positive for active smoking at some point posttransplant, and 57 (15.0%) tested positive repeatedly. Smokers suffered significantly more deaths due to GCAD (21.2% vs. 12.3%, p < 0.05), and due to malignancy (16.3% vs. 5.8%, p < 0.001). In univariate analysis, smoking after heart transplantation shortened median survival from 16.28 years to 11.89 years. After correcting for the effects of pretransplant smoking in time-dependent multivariate analysis, posttransplant smoking remained the most significant determinant of overall mortality (p < 0.00001). We conclude that tobacco smoking after cardiac transplantation significantly impacts survival by accelerating the development of graft vasculopathy and malignancy. We hope that this information will deter cardiac transplant recipients from relapsing, and intensify efforts in improving cessation rates.
SUMMARYIFN-g increases the potential immunogenicity of vascular endothelial cells by up-regulation of intercellular adhesion molecule-1 (ICAM-1) and class I MHC antigen expression and by induction of class II MHC antigens and certain chemokines. In this study the mechanism by which the glycosaminoglycan (GAG) heparin antagonizes the activation of a model endothelium by IFN-g was investigated. Radioligand binding assays demonstrated that total binding of 125 I-IFN-g to the EAhy.926 endothelial hybridoma cell line was reduced in the presence of heparin or heparan sulphate (HS); the structurally dissimilar GAG chondroitin sulphate had no effect. Treatment of the cells with chlorate, a metabolic inhibitor of GAG sulphation, was found to reduce both the subsequent binding of IFN-g and its ability to induce expression of class II MHC antigens. Treatment with heparinase II dramatically reduced the binding of IFN-g, while chondroitin ABC lyase had no effect. A cationic peptide from the C-terminal region of IFN-g was also found to reduce binding of intact IFN-g to the cells. These results appear to demonstrate that IFN-g is sequestered at the surface of endothelial cells by electrostatic interaction between specific basic amino acid residues and sulphated domains on HS, the most abundant endothelial GAG. This interaction is competitively inhibited by heparin, which is structurally related to HS. These observations are consistent with the model that IFN-g is bound by membrane-associated HS before engagement with the high-affinity receptor and signal transduction. Inhibition of the interaction between proinflammatory cytokines and membrane-associated GAG molecules may provide a mechanism for inducing clinically useful immunosuppression.
A very low complication rate can be achieved without recourse to bronchial wrapping, telescoping anastomoses or steroid avoidance. Combined heart-lung transplantation or bronchial revascularisation are not required to achieve reliable bronchial healing.
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