During acute rejection, CD4 and CD8 T cells infiltrate the myocardium and cause myocyte death and dropout. CD4 and CD8 cells use a number of cytotoxic mechanisms, including fas-fas ligand interactions, which lead to apoptotic death. Since fas is expressed on myocytes, we investigated endomyocardial biopsy specimens from cardiac transplant patients to determine whether apoptosis is one of the mechanisms of cell death in acute rejection. Serial sections of individual endomyocardial biopsy specimens from patients histologically diagnosed as having grade 3A rejection (n=22 biopsy specimens), biopsy specimens showing a typical "Quilty effect" (n=10), and specimens with concurrent grade 3A rejection and the Quilty effect (n=6) were evaluated using the C-terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) technique for frequency of apoptosis in myocytes and mononuclear cell infiltrates. None of the examined sections showed detectable evidence of apoptotic myocytes, even within regions clearly showing myocyte damage. Of interest was our consistent finding that 85-98% of mononuclear cell infiltrates within biopsy specimens scored as having grade 3A rejection had undergone apoptosis. In marked contrast, 9 of the 10 specimens with Quilty lesions showed <5% apoptotic mononuclear cells in the endomyocardial infiltrates. Of further interest was our finding of 85-98% apoptotic mononuclear cell infiltrates within Quilty lesions associated with biopsy specimens scored as having grade 3A rejection. The frequency of apoptotic cells determined by the TUNEL technique was confirmed by histological examination of the morphology of the cells and with a technique that involves detection of c-jun. These results prompt a note of caution in the interpretation of data on the phenotype, cytokine profile, Vbeta T cell receptor repertoire, and donor specificity of mononuclear cells cultured and propagated from such cardiac biopsy specimens. The possible reasons for apoptosis of graft-infiltrating mononuclear cells are discussed.

Sera from 29 of 48 patients with idiopathic dilated cardiomyopathy (IDCM) and six of six patients with dilated cardiomyopathy (DCM) secondary to suspected viral myocarditis were shown to react with the branched chain alpha-ketoacid dehydrogenase (BCKD) complex mitochondrial proteins. Whereas sera from only 1 of 26 patients with ischemic heart disease showed reactivity against the BCKD complex protein, 0 of 30 sera from normal human volunteers, 0 of 64 sera from patients with lupus, and 0 of 34 sera from patients with rheumatoid arthritis showed detectable reactivity, denoting an element of specificity for the reactivity of sera from IDCM patients. The major reactivity was localized to the dihydrolipoyl transacylase (E2) component of BCKD complex. By using recombinant techniques, the immunodominant BCKD-E2 epitope recognized by sera from IDCM patients was localized to amino acid (aa) sequences 116 to 134. Each of the IDCM sera that reacted with the native BCKD complex was shown to react with the immunodominant peptide, as defined by a peptide inhibition ELISA and by an ELISA using the reactive peptide conjugated to BSA. Sera from IDCM patients that reacted with the native BCKD complex and the reactive peptide also showed inhibition of BCKD enzyme activity. The possible mechanisms for the induction of the Abs and the implications of these findings for the pathogenesis of IDCM are discussed.

Background: Idiopathic dilated cardiomyopathy (DCM) is a serious heart disease characterized by enlargement of one or both-ventricles and ventricular dysfunction. Although most patients have sporadic disease, 20% have been found to have familial DCM when relatives are investigated by echocardiography. No other factors have been identified to date that consistently distinguish familial from nonfamilial DCM. Although some patients have a family history of DCM, a ''negative'' family history does not exclude familial DCM because affected family members may be presymptomatic or undiagnosed. Because some patients have life-threatening complications at the time of initial assessment of DCM, identifying a serum marker predictive of familial disease would help determine which families would most likely benefit from echocardiographic investigation.Objective: In this study, our objective was to determine whether antiheart autoantibodies could be used to distinguish familial from nonfamilial idiopathic DCM.Methods: We analyzed serum specimens for antiheart antibodies from 19 patients categorized as having familial DCM and 15 classified as having nonfamilial DCM on the basis of echocardiographic investigation of first-degree relatives. The mean duration of disease in these 34 patients was 50 months at the time the serum specimens were obtained.Results: Titers of antibodies against the adenine nucleotide translocator, branched-chain keto acid dehydrogenase, and cardiac myosin did not distinguish between familial and nonfamilial cases of DCM.

BACKGROUND Thrombocytopenia and impaired platelet function after cardiopulmonary bypass (CPB) contribute to postoperative bleeding and may increase blood transfusion requirements. We tested the hypothesis that reversible inhibition of glycoprotein IIb/IIIa integrin-mediated platelet adhesion would reduce postoperative bleeding after CPB. METHODS AND RESULTS Twelve mongrel dogs (21 to 24 kg) underwent 2.5 hours of hypothermic CPB followed by 6 hours of observation. The study group (n = 6) received a 90-micrograms/kg IV bolus of the glycoprotein IIb/IIIa inhibitor Integrelin, followed by continuous infusion (2 micrograms/kg per minute) during CPB; the control group (n = 6) received only drug vehicle. Platelet number and aggregometry, PaO2, and chest tube output were assessed serially. Lung wet weight, histology, and myeloperoxidase activity were also measured. At 120 minutes after CPB, the control group had significantly lower platelet counts (expressed as percent of pre-CPB values) when compared with the Integrelin group (control, 35.2 +/- 4.6%; Integrelin, 68.2 +/- 4.9%; mean +/- SEM; P < .05). Three hundred sixty minutes after CPB, platelet function (expressed as percent of pre-CPB aggregation induced by 10 mumol/L ADP) was better preserved in the Integrelin group (Integrelin, 20.8 +/- 3.0%; control, 43.9 +/- 10.4%; P < .05). The Integrelin group also had less total postoperative blood loss (control, 447 +/- 97 mL; Integrelin, 248 +/- 30 mL; P < .05). PaO2, lung wet weight, histology, and myeloperoxidase activity did not differ significantly between groups. CONCLUSIONS This study demonstrates that inhibition of platelet adhesion during CPB results in (1) less platelet consumption, (2) better preservation of platelet function, and (3) less postoperative bleeding. Reversible platelet inhibition may have clinical utility in minimizing postoperative bleeding and reducing blood transfusions.

BACKGROUND:Although myocardial oxidative tricarboxylic acid (TCA) cycle activity and contractile function are closely linked in normal cardiac muscle, their relation during postischemic reperfusion, when contractility often is reduced, is not well defined.METHODS AND RESULTS:To test the hypothesis that oxidative TCA cycle flux is reduced in reperfused myocardium with persistent contractile dysfunction, TCA cycle flux was measured by analyzing the time course of sequential myocardial glutamate labeling during 13C-labeled substrate infusion with 13C nuclear magnetic resonance spectroscopy in beating isolated rat hearts at 37 degrees C. Total TCA cycle flux, indexed by both empirical and mathematical modeling analyses of the 13C data, was not reduced but rather increased in hearts reperfused after 17-20 minutes of ischemia (left ventricular pressure, 73 +/- 5% of preischemic values) compared with flux in developed pressure-matched controls (e.g., total flux, 2.5 +/- 0.4 versus 1.6 +/- 0.1 mumol.min-1.g wet wt-1, respectively; p < 0.01). No TCA cycle activity was detectable by 13C nuclear magnetic resonance in hearts reperfused after 40-45 minutes of ischemia, which lacked contractile recovery and had ultrastructural evidence of irreversible injury.CONCLUSIONS:These results suggest that TCA cycle activity is not persistently decreased in dysfunctional reperfused myocardium after a brief ischemic episode and therefore cannot account for the reduced contractile function at that time.

Autoantibodies against the adenine nucleotide translocator (ANT), the branched chain alpha-ketoacid dehydrogenase (BCKD) complex proteins, and myosin have been implicated in the pathogenesis of human dilated cardiomyopathy (DCM). Cardiac tissue from patients with DCM and, for control purposes, cardiac tissue from patients with other forms of cardiomyopathy and from patients with no history of cardiac disease were stained with heterologous and ANT-, BCKD-, and myosin-specific affinity-purified sera from DCM patients. Data demonstrate that although anti-myosin stains tissues from both patients and normal controls, the ANT- and BCKD-specific heterologous and affinity-purified sera from DCM patients stain only cardiac tissues from DCM patients. Intense staining in patchy areas of cardiac tissue suggests that abnormal increased expression of these putative autoantigens occurs in discrete areas of cardiac myocytes. The reactivity of the antisera was organ specific and only seen in tissues from DCM patients. The organ and disease specificity of these findings suggests that such expression may play an important role in the pathogenesis of human DCM.