Biomedical subjects

M C Fishbein

Publications and source records attributed to M C Fishbein.

At least 19 recordsLinked to original sources

PubMed2006

Cytoprotective gene HO-1 and chronic rejection in heart transplantation.

Chronic rejection in transplanted hearts or cardiac allograft vasculopathy (CAV) is the leading cause of late death among heart transplant recipients. We hypothesized that induction of HO-1 by D4-F, an apoA-I mimetic peptide with potent antiinflammatory/antioxidant properties, attenuated CAV. We utilized a previously characterized murine model of CAV. B6.C-H2(bml2) hearts were heterotopically transplanted into C57BL/6 mice. In the control group, recipient mice were treated with 20 microg of saline daily. In experimental group I, mice were treated daily with 20 microg of D4-F. In experimental group II, mice were treated daily with 20 microg of D4-F daily, plus CuPP, which does not have any effect on HO-1 activity. In experimental group III, recipient mice were treated with 20 mug of D4-F daily, plus SnPP, which is a competitive inhibitor of HO-1. Donor hearts were harvested on day 24 after transplantation. The donor hearts in the control group developed severe intimal lesions. In experimental group I, treatment with D4-F was associated with upregulation of HO-1 and a marked reduction in intimal lesions, which was consistent in experimental group II. In experimental group III, inhibition of HO-1 was associated with partial restoration of intimal lesions. Induction of HO-1 by an apoA-1 mimetic peptide was effective to control CAV. This class of antiinflammatory peptides, which show an ability to induce HO-1, provides a novel strategy for the treatment of CAV.

Animals↗

PubMed2006

Role of CXCR3 and CCR5 in allograft rejection.

UNLABELLED: Chemokines are known to participate in allograft rejection by mediating leukocyte trafficking. Despite redundancy in chemokine family, several chemokine-chemokine receptor interactions have proven critical in alloimmune responses. We sought to determine the effect of combined blockade of CXCR3 and CCR5, two critical chemokine receptors, in acute rejection. METHODS: Heterotopic heart transplantation was performed using BALB/c to B6/129 mice deficient in CCR5. Following transplantation these mice were treated with goat anti-CXCR3 serum every other day. In the control group, BALB/c hearts were transplanted in wild type B6/129 recipients and treated with goat serum alone. No immunosuppression was given to either group. Recipient mice were then assessed daily for allograft function by abdominal palpation, and graft survival was confirmed by laparotomy. RESULTS: The donor hearts in the control group were rejected at 6 +/- 1 days posttransplantation. Combined blockade of CXCR3 and CCR5 prolonged allograft survival versus control; all allografts survived to 24 days. In addition, there was a decrease in graft infiltrating CD4 and CD8 lymphocytes in the experimental group at 24 days. CONCLUSION: Combined CXCR3 and CCR5 blockade is effective in prolonging allograft survival in a fully MHC mismatched murine model. Combined chemokine blockade holds promise in control of acute rejection in organ transplantation.

Animals↗

PubMed2006

Phosphorylated S6 ribosomal protein: a novel biomarker of antibody-mediated rejection in heart allografts.

We tested the hypothesis that phosphorylation of S6 ribosomal protein (S6RP), a downstream target of the PI3K/Akt/mTOR pathway, is a biomarker of antibody-mediated rejection (AMR) in heart allografts. Primary cultures of human aortic and microvascular endothelial cells (EC) were treated with anti-HLA class I and class II antibodies (Ab) and cell lysates were studied for phosphorylation of S6 ribosmal protein at Serine235/236 (p-S6RP). Treatment of cultured EC with anti-class I and class II Ab stimulated S6RP phosphorylation. Immunohistochemical techniques were used to detect the level of p-S6RP in endomyocardial biopsies (n = 131) from 46 heart transplant recipients and the results were correlated with histopathological diagnosis of rejection, C4d staining, production of posttransplant anti-HLA Ab and clinical outcome. Increased phosphorylation of S6RP in endomyocardial biopsies was significantly associated with the diagnosis of AMR (p < 0.0001). No significant association between acute cellular rejection (ACR) and p-S6RP was observed. C4d staining was positively associated with both AMR and p-S6RP. Posttransplant anti-HLA class II Ab production was also significantly associated with a positive p-S6RP status in cardiac biopsies. These results indicate that p-S6RP is a useful biomarker for the diagnosis of AMR.

Acute Disease↗

PubMed2001

Toll-like receptor-4 is expressed by macrophages in murine and human lipid-rich atherosclerotic plaques and upregulated by oxidized LDL.

BACKGROUND: Inflammation is implicated in atherogenesis and plaque disruption. Toll-like receptor 2 (TLR-2) and TLR-4, a human homologue of drosophila Toll, play an important role in the innate and inflammatory signaling responses to microbial agents. To investigate a potential role of these receptors in atherosclerosis, we assessed the expression of TLR-2 and TLR-4 in murine and human atherosclerotic plaques. METHODS AND RESULTS: Aortic root lesions of high-fat diet-fed apoE-deficient mice (n=5) and human coronary atherosclerotic plaques (n=9) obtained at autopsy were examined for TLR-4 and TLR-2 expression by immunohistochemistry. Aortic atherosclerotic lesions in all apoE-deficient mice expressed TLR-4, whereas aortic tissue obtained from control C57BL/6J mice showed no TLR-4 expression. All 5 lipid-rich human plaques expressed TRL-4, whereas the 4 fibrous plaques and 4 normal human arteries showed no or minimal expression. Serial sections and double immunostaining showed TLR-4 colocalizing with macrophages both in murine atherosclerotic lesions and at the shoulder region of human coronary artery plaques. In contrast to TLR-4, none of the plaques expressed TLR-2. Furthermore, basal TLR-4 mRNA expression by human monocyte-derived macrophages was upregulated by ox-LDL in vitro. CONCLUSIONS: Our study demonstrates that TLR-4 is preferentially expressed by macrophages in murine and human lipid-rich atherosclerotic lesions, where it may play a role to enhance and sustain the innate immune and inflammatory responses. Moreover, upregulation of TLR-4 in macrophages by oxidized LDL suggests that TLR-4 may provide a potential pathophysiological link between lipids and infection/inflammation and atherosclerosis.

Animals↗

PubMed2001

ENA-78 is an important angiogenic factor in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic and often fatal disorder. Fibroplasia and deposition of extracellular matrix are dependent, in part, on angiogenesis and vascular remodeling. We obtained open lung biopsies from patients undergoing thoracic surgery for reasons other than interstitial lung disease (control) (n = 78) and from patients with IPF (n = 91). We found that levels of epithelial neutrophil-activating peptide 78 (ENA-78) were greater from tissue specimens of IPF patients, as compared with control subjects. When ENA-78 was depleted from IPF tissue specimens, tissue-derived angiogenic activity was markedly reduced. Immunolocalization of ENA-78 demonstrated that hyperplastic Type II pneumocytes and macrophages were the predominant cellular sources of ENA-78. These findings support the notion that ENA-78 may be an important additional factor that regulates angiogenic activity in IPF.

Angiogenesis Inducing Agents↗

PubMed2001

Inducible activation of c-Myc in adult myocardium in vivo provokes cardiac myocyte hypertrophy and reactivation of DNA synthesis.

c-Myc, a protooncogene, mediates both proliferative and cellular growth in many cell types. Although not expressed in the adult heart under normal physiological conditions, Myc expression is rapidly upregulated in response to hypertrophic stimuli. Although Myc is capable of sustaining hyperplastic growth in fetal myocytes, the effects of its re-expression in adult postmitotic myocardium and its role in mediating cardiac hypertrophy are unknown. To determine the effects of de novo Myc activity in adult postmitotic myocardium in vivo, we created a novel transgenic model in which Myc is expressed and inducibly activated specifically in cardiac myocytes. Activation of Myc in adult myocardium was sufficient to reproduce the characteristic changes in myocyte size, protein synthesis, and cardiac-specific gene expression seen in cardiac hypertrophy. Despite the increased cardiac mass, left ventricular function remained normal. Activation of Myc also provoked cell cycle reentry in postmitotic myocytes, which led to increased nuclei per myocyte and DNA content per nuclei.

Animals↗

PubMed2001

Allochimeric class I MHC molecules prevent chronic rejection and attenuate alloantibody responses.

BACKGROUND: We have shown that treatment with molecularly engineered, allochimeric [alpha1 hl/u]-RT1.Aa class I MHC antigens bearing donor-type Wistar-Furth (WF, RT1.Au) amino acid substitutions for host-type ACI (RTI.Aa) sequences in the alpha1-helical region induces donor-specific tolerance to cardiac allografts in rat recipients. This study examined the effect of allochimeric molecules on the development of chronic rejection. METHODS: Allochimeric [alpha1 hl/u]-RT1.Aa class I MHC antigenic extracts (1 mg) were administered via the portal vein into ACI recipients of WF hearts on the day of transplantation in conjunction with subtherapeutic oral cyclosporine (CsA, 10 mg/kg/day, days 0-2). Control groups included recipients of syngeneic grafts and ACI recipients of WF heart allografts treated with high-dose CsA (10 mg/kg/day, days 0-6). RESULTS: WF hearts in ACI rats receiving 7 days of CsA exhibited myocardial fibrosis, perivascular inflammation, and intimal hyperplasia at day 80. At day 120, these grafts displayed severe chronic rejection with global architectural disorganization, ventricular fibrosis, intimal hyperplasia, and progressive luminal narrowing. In contrast, WF hearts in rats treated with [alpha1 hl/u]-RT1.Aa molecules revealed only mild perivascular fibrosis, minimal intimal thickening, and preserved myocardial architecture. Alloantibody analysis demonstrated no IgM alloantibodies in all groups. An attenuated, but detectable, anti-WF IgG response was present in recipients receiving allochimeric molecules, with IgG1 and IgG2a subclasses predominating. Immunohistochemical analysis of allografts demonstrated minimal T cell infiltration and IgG binding to vascular endothelium. CONCLUSION: Treatment with allochimeric molecules prevents the development of chronic rejection. Such effect may be in part caused by deviation of host alloantibody responses.

Amino Acid Sequence↗

PubMed2001

Rantes production during development of cardiac allograft vasculopathy.

BACKGROUND: RANTES (regulated on activation, normal T cell expressed and secreted) production has been shown to correlate with mononuclear cell recruitment and precede intimal thickening in cardiac allograft vasculopathy (CAV). However, the cells that produce RANTES in CAV are undefined. Therefore, in an MHC II-mismatched murine model of CAV, we sought to (1) define the cellular sources of RANTES and (2) determine the role of CD4+ lymphocytes in RANTES production during CAV development. METHODS: B6.CH-2bm12 strain donor hearts were transplanted heterotopically into wild-type (WT) or CD4 knockout (CD4KO) C57BL/6 mice (MHC II mismatch). No immunosuppression was used. Recipients were sacrificed at 7, 14, and 24 days. Intragraft RANTES gene expression and protein levels were determined with ribonuclease protection assay and ELISA, respectively. At days 7 and 24, RANTES production by graft-infiltrating cells was defined with intracellular RANTES staining and multicolor FACS analysis. Intimal thickening was quantitated morphometrically. In murine hearts and in six explanted human hearts with advanced CAV, RANTES was also localized immunohistochemically. RESULTS: NK, NKT, and gammadelta+ cells, in addition to CD4+, CD8+ lymphocytes, and CD11b+ macrophages, produced RANTES in early and late stages of CAV. RANTES-producing NK, NKT, and gammadelta+ cells tripled in number during CAV development; by day 24, NK and gammadelta+ cells each outnumbered CD4+ lymphocytes and CD11b+ macrophages. The presence of CD4+ lymphocytes was required for sustained RANTES production in allografts, which correlated with mononuclear cell recruitment and preceded intimal thickening. In murine and explanted human hearts with advanced CAV, RANTES immunolocalized with graft-infiltrating mononuclear cells and vessel wall cells. CONCLUSIONS: We present evidence that other cell types in addition to CD4+, CD8+ T lymphocytes, and CD11b+ macrophages contribute significantly to RANTES production in CAV. In this MHC II-mismatched murine model of CAV, sustained RANTES production requires CD4+ lymphocytes, correlates with mononuclear cell recruitment, and precedes intimal thickening. In experimental and human CAV, vessel wall cells may also produce RANTES. Interventions aimed at inhibiting RANTES production in CAV may need to target several types of cells, and neutralization of RANTES bioactivity may reduce mononuclear cell recruitment and CAV development.

Animals↗

PubMed2001

CD8+ lymphocytes augment chronic rejection in a MHC class II mismatched model.

UNLABELLED: Chronic rejection, or cardiac allograft vasculopathy (CAV), remains the leading cause of late death in heart transplant recipients. The precise role and contributions of T lymphocyte subsets to CAV development remains unknown. METHODS: Donor hearts from B6.C-H2bm12 mice were transplanted into T lymphocyte subset knockout recipients and T lymphocyte-reconstituted nude recipients. No immunosuppression was used. Intimal proliferation was measured morphometrically. In vitro studies were performed to analyze the donor-specific activation status of recipient CD8+ lymphocytes by examining cellular proliferation, interleukin-2 secretion, and interleukin-2Ralpha expression. Intracellular cytokine staining assay was performed to determine both the profile and source of intragraft cytokines. RESULTS: Hearts transplanted into wild-type recipients developed severe CAV by 24 days. Intimal lesions were absent in the hearts that were transplanted into nude and CD4-/- knockout mice (containing CD8+ lymphocytes). In contrast, the donor hearts in CD8-/- knockout recipients (containing CD4+ lymphocytes) developed CAV, but significantly less than in wildtype. Adoptive transfer of T lymphocyte subset populations into nude recipients confirmed that CAV was absolutely contingent on CD4+ lymphocytes, and that CD8+ lymphocytes played an additive role in intimal lesion progression in the presence of CD4+ lymphocytes. Although CD8+ lymphocytes alone did not cause CAV in vivo, we demonstrated that MHC class II disparate alloantigens activated CD8+ lymphocytes both in vivo and in vitro. Finally, both CD4+ and CD8+ lymphocytes contributed to the intragraft IL-2 and IFN-gamma production. CONCLUSIONS: In this MHC class II mismatched murine model, CAV is a T lymphocyte dependent event, and absolutely contingent on the presence of CD4+ lymphocytes. Furthermore, CD8+ lymphocytes (1) are activated by MHC class II disparate antigens and (2) play a significant role in the progression of lesion development. Finally, both CD4+ and CD8+ lymphocytes contribute to CAV development via secretion of IFN-gamma, a known mediator of CAV in this model.

Animals↗

PubMed2001

Dynamics of intramural and transmural reentry during ventricular fibrillation in isolated swine ventricles.

The intramural dynamics of ventricular fibrillation (VF) remain poorly understood. Recent investigations have suggested that stable intramural reentry may underlie the mechanisms of VF. We performed optical mapping studies of VF in isolated swine right ventricles (RVs) and left ventricles (LVs). Nine RV walls were cut obliquely in their distal edge exposing the transmural surface. Six LV wedge preparations were also studied. Results showed that intramural reentry was present. In RV, 28 of 44 VF episodes showed reentry; 15% of the activation pathways were reentrant. Except for 4 episodes, reentry was transmural, involving subendocardial structures as the papillary muscle (PM) or trabeculae. In LV, reentry was observed in 27 of 27 VF episodes; 23% of the activations were part of reentrant pathways (P<0.05 compared with RV). All LV reentrant pathways were truly intramural (confined to the wall) and were frequently located at the PM insertion. In both ventricles, reentry was spatially and temporally unstable. Histological studies showed abrupt changes in fiber orientation at sites of reentry and wave splitting. Connexin 40 immunostaining demonstrated intramyocardial Purkinje fibers at sites of reentry in the PM root and around endocardial trabeculae. Our results confirm that reentry is frequent-but unstable-in the myocardial wall during VF. In RV, reentry is mostly transmural and requires participation of subendocardial structures. The LV has a greater incidence of reentry and is intramural. Anisotropic anatomic structures played key roles in the generation of wave splitting and in the maintenance of reentry.

Animals↗

PubMed2001

Increased wave break during ventricular fibrillation in the epicardial border zone of hearts with healed myocardial infarction.

BACKGROUND: The action potential duration (APD) restitution hypothesis of wave break during ventricular fibrillation (VF) in the epicardial border zone (EBZ) of hearts with chronic myocardial infarction is unknown. METHODS AND RESULTS: VF was induced by rapid pacing, and the EBZ with the two adjoining sites (right ventricle and lateral left ventricle) were sequentially mapped in random order in 7 open-chest anesthetized dogs 6 to 8 weeks after left anterior descending artery occlusion and in 4 control dogs. At each site, 3 seconds of VF was mapped with 477 bipolar electrodes 1.6 mm apart. The number of wave fronts and approximate entropy were significantly (P:<0.01) higher in the EBZ than all other sites in both groups independent of the rate of invasion of new wave fronts and epicardial breakthroughs. The higher wavelet density in the EBZ was caused by increased (P:<0.01) incidence of spontaneous wave breaks. There was no difference between the two groups in either reentry period (80 episodes) or VF cycle length. Reentry in the EBZ had a smaller core perimeter, slower rotational speed, and a small or no excitable gap (P:<0.01), often causing termination after one rotation. The dynamic monophasic action potential duration restitution curve in the EBZ had longer (P:<0.01) diastolic intervals, over which the slope was >1. Connexin43-positive staining was significantly (P:<0.01) and selectively reduced in the EBZ. CONCLUSIONS: A selective increase in wave break and alteration of reentry occur in the EBZ during VF in hearts with healed myocardial infarction. Increased wave break in the EBZ is compatible with the action potential duration restitution hypothesis.

Action Potentials↗

PubMed2001

Pulmonary veins and ligament of Marshall as sources of rapid activations in a canine model of sustained atrial fibrillation.

BACKGROUND: In dogs, chronic rapid pacing may result in sustained atrial fibrillation (AF). However, activation patterns in pacing-induced sustained AF are unclear. METHODS AND RESULTS: We induced sustained AF (>48 hours) in 6 dogs by rapid pacing for 139+/-84 days. We then performed computerized atrial epicardial mappings and recorded the activations in the ligament of Marshall (LOM) and the pulmonary veins (PVs). During AF, mean activation cycle length in the right atrial free wall (126+/-17 ms) was significantly longer than that in the left atrial free wall (96+/-5 ms, P:=0.006). In addition, mean activation cycle length in the left atrial free wall was significantly longer than that in the LOM (84+/-5 ms, P:<0.001), the left inferior PV (81+/-4 ms, P:=0.001), and the left superior PV (85+/-7 ms, P:=0.003). Similarly, the dominant frequency was highest in the LOM and the PVs (range 11.2 to 13.3 Hz), followed by the left and right atria (P:<0.001). In all dogs studied, rapid and complicated electrograms were consistently observed at the LOM and the PVs. During AF, both wandering wavelets and organized reentry were present. There were more wave fronts in the left atrium than in the right atrium (P:<0.001). CONCLUSIONS: In chronic pacing-induced sustained AF, the LOM and the PVs are the sources of rapid activations. The mechanism by which the left atrium activates faster and has more wave fronts than the right atrium may relate to the fact that the left atrium is closer to the sources of rapid activations.

Analysis of Variance↗

PubMed2001

Nerve sprouting and sympathetic hyperinnervation in a canine model of atrial fibrillation produced by prolonged right atrial pacing.

BACKGROUND: Long-term rapid atrial pacing may result in atrial fibrillation (AF) in dogs. Whether there is histological evidence for neural remodeling is unclear. METHOD AND RESULTS: We performed rapid right atrial pacing in 6 dogs for 111+/-76 days to induce sustained AF. Tissues from 6 healthy dogs were used as controls. Immunocytochemical staining of cardiac nerves was performed using anti-growth-associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. In dogs with AF, the density of GAP43-positive and TH-positive nerves in the right atrium was 470+/-406 and 231+/-126 per mm(2), respectively, which was significantly (P:<0.001) higher than the nerve density in control tissues (25+/-32 and 88+/-40 per mm(2), respectively). The density of GAP43-positive and TH-positive nerves in the atrial septum was 317+/-36 and 155+/-85 per mm(2), respectively, and was significantly (P:<0.001) higher than the nerve density in control tissues (9+/-13 and 30+/-7 per mm(2), respectively). Similarly, the density of GAP43-positive and TH-positive nerves in the left atrium of dogs with AF was 119+/-61 and 91+/-40 per mm(2), respectively, which was significantly (P:<0.001) higher than the nerve density in control tissues (10+/-15 and 38+/-39 per mm(2), respectively). Furthermore, in dogs with AF, the right atrium had a significantly higher nerve density than the left atrium. Microscopic examinations revealed an inhomogeneous distribution of cardiac nerves within each sampling site. CONCLUSIONS: Significant nerve sprouting and sympathetic hyperinnervation are present in a canine model of sustained AF produced by prolonged right atrial pacing. The magnitude of nerve sprouting and hyperinnervation was higher in the right atrium than in the left atrium.

Animals↗

PubMed2001

Tissue characterization and calcification potential of commercial bioprosthetic heart valves.

BACKGROUND: Tissue properties may contribute to intrinsic calcification of bioprosthetic heart valves. Phospholipids have been proposed as potential nucleation sites for calcification. Other tissue properties might also be important in calcification. METHODS: Commercial and control bioprosthetic valve tissues were characterized by shrinkage temperature, moisture content, free amine content, phospholipid content, and calcification level after 90-day rat subcutaneous implantation as described. RESULTS: Shrinkage temperature, moisture content, and free amine content were typical for glutaraldehyde-cross-linked tissues. Phospholipid and calcium levels varied considerably among valve types. There was a significant correlation between phospholipid levels and calcification (r = 0.63, p = 0.04). Sulzer Carbomedics Mitroflow and Toronto SPV valve tissues had significantly more calcification than other commercial bioprostheses in this study (p < 0.01). Carpentier-Edwards Duraflex, CE SAV, and CE PERIMOUNT valve tissues had significantly less calcification than Medtronic Mosaic in this animal model (p < 0.02). CONCLUSIONS: Processes that reduce phospholipid levels are associated with reduced calcification in the rat subcutaneous model. Significant differences in calcification level were found among commercially available valves. The clinical significance of these results is unknown.

Bioprosthesis↗

PubMed2001

Sympathetic nerve sprouting, electrical remodeling and the mechanisms of sudden cardiac death.

The purpose of this article is to review the nerve sprouting hypothesis of sudden cardiac death. It is known that sympathetic stimulation is important in the generation of sudden cardiac death. For example, there is a diurnal variation of sudden death rate in patients with myocardial infarction. Beta blockers, or drugs with beta blocking effects, are known to prevent sudden cardiac death. It was unclear if the cardiac nerves in the heart play only a passive role in the mechanisms of sudden death. To determine if nerve sprouting and neural remodeling occur after myocardial infarction, we performed immunocytochemical studies of cardiac nerves in explanted native hearts of transplant recipients. We found that there was a positive correlation between nerve density and a clinical history of ventricular arrhythmia. Encouraged by these results, we performed a study in dogs to determine whether or not nerve growth factor (NGF) infusion to the left stellate ganglion can facilitate the development of ventricular tachycardia (VT), ventricular fibrillation (VF), and sudden cardiac death (SCD). The results showed that augmented myocardial sympathetic nerve sprouting through NGF infusion plus atrioventricular (AV) block and MI result in a 44% incidence (four of nine dogs) of SCD and a high incidence of VT in the chronic phase of MI. In contrast, none of the six dogs (with AV block and MI) without NGF infusion died suddenly or had frequent VT episodes. Based on these findings, we propose the nerve sprouting hypothesis of ventricular arrhythmia and SCD. The hypothesis states that MI results in nerve injury, followed by sympathetic nerve sprouting and regional (heterogeneous) myocardial hyperinnervation. The coupling between augmented sympathetic nerve sprouting with electrically remodeled myocardium results in VT, VF and SCD. Modification of nerve sprouting after MI may provide a novel opportunity for arrhythmia control.

Animals↗

PubMed2001

Differential expression of RANTES chemokine, TGF-beta, and leukocyte phenotype in acute cellular rejection and quilty B lesions.

BACKGROUND: Because of the complexity of the trabeculated endocardial surface and tangential histologic sectioning, the differentiation of acute cellular rejection (ACR) from Quilty B lesions (QB) in endomyocardial biopsies (EMBs) is problematic. We hypothesized that the phenotype chemokine RANTES (regulated upon activation, normal T cell expressed and secreted) expression of infiltrating cells and the pattern of expression of transforming growth factor-beta (TGF-beta) may distinguish ACR from QB. In previous studies, the number of RANTES-positive cells and the expression of TGF-beta correlated with the severity of rejection. METHODS: We used immunohistochemical techniques to stain sections of human EMBs with only QB (n = 14) or with only ACR (International Society for Heart and Lung Transplantation Grades 1A and 1B, n = 7; Grades 3A and 3B, n = 7) for B (CD20) and T-lymphocytes (CD3), macrophages (CD68), RANTES, and TGF-beta expression. We graded the percentage of positive cells from 0 to 4 (1 = 1% to 25%; 2 = 26% to 50%; 3 = 51% to 75%, and 4 = 76% to 100%). RESULTS: When ACR was compared with QB, we found no difference in the proportion of myocardial B cells (0.9 +/- 0.3 vs 1.1 +/- 0.3, p = 0.17); however, we found a lesser proportion of T cells (1.8 +/- 0.5 vs. 2.8 +/- 0.9, p <0.01) but more macrophages (2.9 +/- 0.5 vs. 1.1 +/- 0.6, p < 0.0001) in ACR than in QB. We also found more RANTES-positive leukocytes in ACR vs. QB (2.8 +/- 1.3 vs. 1.9 +/- 0.9, p = 0.03). In QB, many endocardial vessels stained for TGF-beta (2.9 +/- 1.6). Myocardial vessels and injured myocytes in both ACR and QB expressed TGF-beta. CONCLUSIONS: In ACR, although T-lymphocytes are numerous, more than 50% of infiltrating cells are macrophages and more than 50% express RANTES. In QB lesions, more than 50% of infiltrating cells are T-lymphocytes and less that 50% of leukocytes will express RANTES. B cells are present in both ACR and QB, but on average comprise only 25% of the cells present. Thus, a relatively simple immunohistochemical analysis of endomyocardial biopsies may be useful in distinguishing ACR from QB.

B-Lymphocytes↗

PubMed2001

Noninvasive transthoracic low frequency ultrasound augments thrombolysis in a canine model of acute myocardial infarction--evaluation of the extent of ST-segment resolution.

BACKGROUND: Recently it has been demonstrated that transcutaneous delivery of ultrasound combined with tissue plasminogen activator (tPA) is more effective than tPA alone in recanalizing acutely thrombosed canine coronary arteries. In the present study, we investigated the incidence of partial (> or =50%) and complete (> or =70%) ST-segment elevation resolution in the precordial leads of dogs with experimental acute myocardial infarction that were treated with tissue plasminogen activator (tPA) alone or in combination with noninvasive transcutaneous delivery of high-intensity low frequency (27[emsp3 ]kHz) ultrasound. METHODS: Thrombotic coronary occlusions were induced in the midportion of left anterior descending (LAD) coronary artery by electrical injury in 24 dogs. All dogs were given intravenous heparin and tPA. Dogs were randomized to tPA alone (n=12) or combined tPA and adjunctive transcutaneous ultrasound (US) delivery (n=12). Electrocardiograms were recorded at 1) baseline, 2) after coronary occlusion just before initiation of therapy, 3) when coronary angiography showed recanalization of the coronary artery (or at 90 minutes after initiation of therapy if reperfusion did not occur before then) and 4) 90 minutes later. ST amplitude was measured in all 6 precordial leads. RESULTS: ST-segment amplitude at baseline was comparable between the tPA and the US group. Before initiation of therapy, sum of ST-segment elevation tended to be higher in the US group. At reperfusion and 90 minutes thereafter, sum of ST-segment amplitude tended to be smaller for the US group than in the tPA group (p<0.001 for the time effect; p=0.118 for the time x group interaction). Up to 90 minutes after initiation of therapy >/=50% resolution of the sum of precordial ST elevation was detected in 7 out of 11 dogs (63.6%) in the tPA group versus 10 out of 11 dogs (90.9%) in the US group. Ninety minutes thereafter, 3 out of 7 dogs in the tPA group (42.9%) versus 9 of 11 dogs in the US group (81.8%) had >/=50% resolution of the sum of precordial ST elevation. CONCLUSIONS: The combination of tPA with noninvasive transcutaneous delivery of low frequency high-intensity ultrasound resulted in greater resolution of ST-segment elevation when reperfusion occurs and 90 minutes thereafter, as well as a higher rate of epicardial coronary artery reperfusion.

Animals↗

PubMed2001

Modulation of QT interval by cardiac sympathetic nerve sprouting and the mechanisms of ventricular arrhythmia in a canine model of sudden cardiac death.

INTRODUCTION: We previously reported that there is a high incidence of sudden cardiac death (SCD) in dogs with myocardial infarction (MI), complete AV block (CAVB), and nerve growth factor (NGF) infusion to the left stellate ganglion (LSG). Whether or not QT interval prolongation underlines the mechanism of SCD was unclear. METHODS AND RESULTS: We analyzed QT intervals in three groups of dogs. All dogs had CAVB and MI. The LSG group (n = 9) and right stellate ganglion (RSG) group (n = 6) received NGF infusion via the osmotic pumps over a 5-week period to LSG and RSG, respectively. The control group (n = 6) received no NGF. The dogs either died suddenly or were sacrificed within 2 to 3 months after MI. Heart rhythm and QT and RR intervals were monitored using implantable cardioverter defibrillator ECG recordings. There was a time-dependent increase of QTc intervals in the LSG group and a time-dependent decrease of QTc intervals in the RSG group. At the end of NGF infusion, QTc intervals in the LSG group (408 +/- 41 msec) were significantly longer than those in the control (350 +/- 41 msec; P < 0.05) and RSG groups (294 +/- 23 msec; P < 0.01). In the LSG group, 4 of 9 dogs died of SCD. There was no SCD in either the RSG or control group. Immunocytochemical staining showed NGF infusion to LSG and RSG resulted in left and right ventricular sympathetic nerve sprouting and hyperinnervation, respectively. CONCLUSION: NGF infusion to the LSG in dogs with MI and CAVB resulted in increased QT interval and incidence of ventricular tachycardia, ventricular fibrillation, and SCD, whereas NGF infusion to the RSG shortened QT interval and reduced the incidence of ventricular tachycardia. These findings indicate that QT interval prolongation is causally related to the occurrence of ventricular arrhythmia in dogs with nerve sprouting, MI, and CAVB.

Animals↗