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At least 811 records · Page 45Linked to original sources
PubMed1997

Inducible nitric oxide synthase expression in coronary arteries of transplanted human hearts with accelerated graft arteriosclerosis.

Inducible nitric oxide synthase (iNOS) is a high-output isoform of NOS that produces nitric oxide (NO), a nonspecific immune effector molecule. In some animal models of autoimmunity, the induction of iNOS has been shown to lead to inflammation and tissue damage, and it has been suggested that iNOS is an immune mediator in humans as well. Using in situ hybridization and immunohistochemical techniques, we demonstrate that iNOS mRNA and protein are present in the coronary arteries of transplanted human hearts with accelerated graft arteriosclerosis (AGA). iNOS is expressed in cells morphologically consistent with macrophages in the neointima of 7 of 10 of the transplanted vessels with AGA that were examined. In serial sections, these same cells express the macrophage marker CD68. In contrast, iNOS is absent from five native coronary arteries with atherosclerosis and absent from two normal coronary arteries. Although iNOS is expressed in macrophages in AGA, its role in the pathogenesis of AGA is unknown.

Adolescent↗
PubMed1997

Graft arteriosclerosis-induced myocardial pathology in heart transplant recipients: predictive value of endomyocardial biopsy.

BACKGROUND: Ischemic myocardial pathology resulting from graft arteriosclerosis (GA) includes subendocardial myocyte vacuolization (SEMV), indicative of sublethal ischemic injury, and coagulative myocyte necrosis, acute and healing (CMN), indicative of infarction. METHODS: To assess the sensitivity and specificity of myocardial pathology resulting from GA in endomyocardial biopsy specimens, we correlated SEMV and CMN in the final three biopsy specimens (mean interval from last biopsy to death 23 +/- 20 days) with autopsy findings from 30 heart transplant recipients who survived more than 3 months and died of GA (n = 16) or of other causes (n = 14). The two groups were similar in other parameters. RESULTS: Myocardial ischemic injury was present at autopsy in all 16 patients with GA with the following distribution: SEMV (n = 13) nine right ventricle (RV) and left ventricle (LV), four LV only; focal CMN (n = 8) six RV and LV, two LV only; subendocardial infarct (n = 3) three LV only; and transmural infarct (n = 3) one RV, two LV. Ischemic injury was present in the RV of 11 of 16 patients with GA. Of patients without GA, one had SEMV at autopsy; none had infarcts. Ischemic myocardial pathology was present in 10 of 48 biopsy specimens from patients with GA compared with one of 41 biopsy specimens from patients without GA (p < 0.05). The specificity of SEMV on biopsy was 98%, but sensitivity was only 17%. The positive predictive value for ischemic injury was 92%, and negative predictive value was 51%. CONCLUSIONS: Myocardial pathology resulting from ischemia was present at autopsy in all patients dying of GA. Although more prevalent in the LV, 69% of patients had ischemic myocardial pathology in the RV, where it may be accessible to biopsy. Ischemic myocardial pathology in biopsy specimens is highly specific but far less sensitive, for diagnosing GA.

Adult↗
PubMed1998

Coronary arteriosclerosis after T-cell-mediated injury in transplanted mouse hearts: role of interferon-gamma.

This study evaluated the contribution of acute parenchymal rejection and interferon (IFN)-gamma to the development of graft arterial disease (GAD) in totally allogeneic murine cardiac transplants. BALB/c (H-2d) hearts were transplanted into wild-type C57BL/6 (B6, H-2b) or B6 IFN-gamma-deficient (GKO) recipient mice. Assessing the role of acute parenchymal rejection in the GAD process involved two different immunosuppression protocols using anti-CD4 and -CD8 monoclonal antibodies (MAbs): virtually complete long-term immunosuppression (denoted as complete immunosuppression) was achieved by administering both MAbs 6, 3, and 1 day before transplantation and weekly thereafter; in contradistinction, a single, early, transient episode of rejection (transient rejection) was attained by administering MAbs beginning 4 days after transplant and then at weekly intervals. The extent and duration of T cell depletion under these two regimens were evaluated using flow cytometric analysis of peripheral blood lymphocytes. After a single injection of MAbs, peripheral blood CD4+ and CD8+ T cell depletion was approximately 98% at 1 week and approximately 88% at 2 weeks. After three injections (analogous to days 6, 3, and 1 before transplant), peripheral blood CD4+ and CD8+ T cell depletion was >98% at 2 weeks and approximately 87% at 4 weeks. Functioning cardiac allografts were removed at 8 and 12 weeks after transplant and analyzed by hematoxylin and eosin, elastic tissue, and immunohistochemical stains, and the severity of parenchymal rejection versus GAD was scored. With complete immunosuppression (antibody before and after transplant), BALB/c allografts showed little parenchymal rejection or GAD, suggesting that persistent depletion of T cells blocked subsequent development of GAD. However, even a single transient acute rejection episode allowed the subsequent development of GAD accompanied by augmented major histocompatibility complex (MHC) class II, VCAM-1, and ICAM-1 expression at 12 weeks; these allografts showed no residual CD4+ or CD8+ T cells. In comparison, allografts undergoing transient rejection in GKO recipients did not develop GAD, despite persistent macrophage and natural killer cell (NK) infiltrates comparable to those seen in wild-type recipients. Moreover, the arterioles of hearts transplanted into GKO recipients showed no or minimal increases in MHC class II, ICAM-1, and VCAM-1 relative to baseline expression. In conclusion, a single episode of allogeneic injury mediated by T cells suffices to evoke subsequent graft arteriosclerosis, even in the absence of additional T-cell-mediated injury, and the process appears to depend on IFN-gamma.

Animals↗
PubMed1998

The continuing challenge of cardiac transplant arteriosclerosis.

Coronary arteriosclerosis of the graft, a manifestation of CAV, continues to limit the long-term success of cardiac transplantation. It is characterized by vascular injury induced by a variety of noxious stimuli, including the humoral and cellular immune system response to the allograft, ischemia-reperfusion injury, viral infection, immunosuppressive drugs, and classical risk factors. The proliferative and obstructive vascular lesions are thought to develop through repetitive endothelial injury followed by repair response. T lymphocytes, macrophages and neutrophils migrate to the subendothelial area via the activity of endothelial adhesion molecules, and, in turn, produce various cytokines and growth factors which cause progression of the process. Development of anti-endothelial antibodies may progress CAV in specific settings. Intravascular ultrasound studies reveal a dual morphology with donor-transmitted or de novo focal, noncircumferential plaques in proximal segments and/or a diffuse, concentric pattern of intimal proliferation observed in distal segments. In addition to the morphological alterations, functional endothelial and smooth muscle cell alterations may occur independently and transiently. The use of cyclosporine A levels > 3 mg/kg/day, HMG-CoA-reductase inhibitors and calcium antagonists has been shown to decrease the progression of CAV. Strategies for blocking T-cell costimulation and expression of adhesion molecules, cytokines and antiendothelial antibodies, as well as, antiproliferative drugs, methods to augment endogenous nitric oxide bioavailability and newer immunosuppressive regimens may be protective to endothelial injury and subsequent development of CAV. Revascularization procedures have an established, but very limited role in the setting of significant focal lesions. The ethical dilemma surrounding retransplantation, however, is considerable because of the scarcity of donor hearts.

Animals↗
PubMed1976

A comparison of three methods of detecting ventricular incoordination in man, and the relation of their results to the amount of coronary arteriosclerosis.

The results secured by three tests for cardiac incoordination have been compared in over 100 cardiac cases. The Bcg found the abnormality more frequently than did Vgm and PDmax, the probable reasons for this are discussed. The cases in which cardiac incoordination was detected showed, on the average, more coronary arteriosclerosis than those whose hearts beat normally.

Adult↗