Community-acquired respiratory viruses (CARV) can accelerate the development of lung allograft dysfunction, but the immunologic mechanisms are poorly understood. The chemokine receptor CXCR3 and its chemokine ligands, CXCL9, CXCL10, and CXCL11 have roles in the immune response to viruses and in the pathogenesis of bronchiolitis obliterans syndrome, the predominant manifestation of chronic lung allograft rejection. We explored the impact of CARV infection on CXCR3/ligand biology and explored the utility of CXCR3 chemokines as biomarkers for subsequent lung allograft dysfunction. Seventeen lung transplant recipients with CARV infection had bronchoalveolar lavage fluid (BALF) available for analysis. For comparison, we included 34 BALF specimens (2 for each CARV case) that were negative for infection and collected at a duration post-transplant similar to a CARV case. The concentration of each CXCR3 chemokine was increased during CARV infection. Among CARV infected patients, a high BALF concentration of either CXCL10 or CXCL11 was predictive of a greater decline in FEV1 6 months later. CXCR3 chemokine concentrations provide prognostic information and this may have important implications for the development of novel treatment strategies to modify outcomes following CARV infection.
Lung transplantation; community-acquired respiratory viruses; respiratory viral infection; chemokines; rejection
Antibody-mediated rejection (AMR) has been associated with poor outcome after heart transplantation. The diagnosis of AMR usually includes endomyocardial biopsy findings of endothelial cell swelling, intravascular macrophages, C4d+ staining, and associated left ventricular dysfunction. The significance of AMR findings in biopsy specimens of asymptomatic heart transplant patients (normal cardiac function and no symptoms of heart failure) is unclear.
Between July 1997 and September 2001, AMR was found in the biopsy specimens of 43 patients. Patients were divided into 2 groups: asymptomatic AMR (AsAMR, n = 21) and treated AMR (TxAMR with associated left ventricular dysfunction, n = 22). For comparison, a control group of 86 contemporaneous patients, without AMR, was matched for age, gender, and time from transplant. Outcomes included 5-year actuarial survival and development of cardiac allograft vasculopathy (CAV). Patients were considered to have AMR if they had ≥ 1 endomyocardial biopsy specimen positive for AMR.
The 5-year actuarial survival for the AsAMR (86%), TxAMR (68%), and control groups (79%) was not significantly different (p = 0.41). Five-year freedom from CAV (≥ 30% stenosis in any vessel) was AsAMR, 52%; TxAMR, 68%; and control, 79%. Individually, freedom from CAV was significantly lower in the AsAMR group compared with the control group (p = 0.02). There was no significant difference between AsAMR vs TxAMR and TxAMR vs control for CAV.
Despite comparable 5-year survival with controls after heart transplantation, AsAMR rejection is associated with a greater risk of CAV. Trials to treat AsAMR to alter outcome are warranted.
Intra-myocardial nerve sprouting after myocardial infarction is associated with ventricular arrhythmias (VAs). Whether human stellate ganglia remodel in association with cardiac pathology is unknown. The purpose of this study was to determine whether cardiac pathology is associated with remodeling of the stellate ganglia in humans.
Methods and Results
Left stellate ganglia (LSG) were collected from patients undergoing sympathetic denervation for intractable ventricular arrhythmias, and from cadavers, along with intact hearts. Clinical data on patients and cadaveric subjects were reviewed. We classified ganglia from normal; scarred; and non-ischemic cardiomyopathic hearts without scar as NL (n=3); SCAR (n=24); and NICM (n=7), respectively. Within LSG, neuronal size, density, fibrosis, synaptic density and nerve sprouting were determined. Nerve density and sprouting were also quantified in cadaveric hearts. Mean neuronal size in NL, SCAR, and NICM groups were; 320±4μm2, 372±10μm2,and 435±10μm2 (p=0.002). No significant differences in neuronal density and fibrosis were present between the groups. Synaptic density in SCAR and NICMganglia were 57.8±11.2um2/ mm2 (p=0.039) and 44.5±7.9um2/ mm2 (p=0.084) respectively, compared to the NL, 17.8±7um2/ mm2 (overall p=0.162). There were no significant differences in LSG nerve sprouting or myocardial nerve density between the groups.
Neuronal hypertrophy withinLSGis associated with chronic cardiomyopathy in humans. Ganglionic and myocardial nerve sprouting and nerve density were not significantly different. These changes may be related to increased cardiac sympathetic signaling and VAs. Further studies are needed to determine the electrophysiologic consequences of extra-cardiac neuronal remodeling in humans.
cardiomyopathy; nervous system; autonomic; nervous system; sympathetic; ventricular arrhythmia
Ventricular fibrillation (VF) is the primary mechanism of cardiac arrest in the vast majority of sudden death patients. Whether similar modes and mechanisms of death can be generalized to denervated hearts in orthotopic heart transplantation (OHT) patients is unknown.
The purpose of this study was to determine the mode and mechanisms of death in patients who have undergone cardiac transplantation.
We analyzed the outcomes of 628 patients who underwent OHT between January 1994 and December 2004. The mode of death was classified as either sudden death (SD) or non-sudden death (NSD). The first documented rhythm taken at the time of arrest was also reviewed to determine the mechanism of cardiac arrest.
During a mean follow up of 76 months, 194 patients expired. Of these, the mode of death could be determined in 116 patients (60%). Forty-one patients (35%) died from SD and 75 patients (65%) died of NSD. The first documented rhythm of death was available in 91 patients (26 SD and 65 NSD). The terminal rhythms in patients who died suddenly were: asystole (34%), pulseless electrical activity (PEA) (20%), and VF (10%). In NSD patients, the terminal rhythms were asystole (73%), followed by VF (7%), and PEA (7%), p<0.001 compared to SD patients.
SD represented the mode of death in 35% of OHT patients. The main mechanisms underlying SD in this population were asystole and PEA, suggesting that denervation of the donor heart, among other post-transplant changes, may alter susceptibility to VF.
heart transplantation; sudden death; ventricular fibrillation
Cellular heterogeneity is an integral part of cancer development and progression. Progression can be associated with emergence of cells that exhibit high phenotypic plasticity (including “de-differentiation” to primitive developmental states), and aggressive behavioral properties (including high tumorigenic potentials). We observed that many biomarkers that are used to identify Cancer Stem Cells (CSC) can label cell subsets in an advanced clinical stage of lung cancer (malignant pleural effusions, or MPE). Thus, CSC-biomarkers may be useful for live sorting functionally distinct cell subsets from individual tumors, which may enable investigators to hone in on the molecular basis for functional heterogeneity. We demonstrate that the CD44hi (CD44-high) cancer cell subsets display higher clonal, colony forming potential than CD44lo cells (n = 3) and are also tumorigenic (n = 2/2) when transplanted in mouse xenograft model. The CD44hi subsets express different levels of embryonal (de-differentiation) markers or chromatin regulators. In archived lung cancer tissues, ALDH markers co-localize more with CD44 in squamous cell carcinoma (n = 5/7) than Adeno Carcinoma (n = 1/12). MPE cancer cells and a lung cancer cell line (NCI-H-2122) exhibit chromosomal abnormalities and 1p36 deletion (n = 3/3). Since miR-34a maps to the 1p36 deletion site, low miR-34a expression levels were detected in these cells. The colony forming efficiency of CD44hi cells, characteristic property of CSC, can be inhibited by mir-34a replacement in these samples. In addition the highly tumorigenic CD44hi cells are enriched for cells in the G2 phase of cell cycle.
Purpose: The EGFR tyrosine kinase inhibitors (TKIs) demonstrate efficacy in NSCLC patients whose tumors harbor activating EGFR mutations. However, patients who initially respond to EGFR TKI treatment invariably develop resistance to the drugs. Known mechanisms account for approximately 70% of native and acquired EGFR TKI resistance. In the current study we investigated a novel mechanism of NSCLC resistance to erlotinib. Experimental Design: The mechanisms of acquired erlotinib resistance were evaluated by microarray analysis in thirteen NSCLC cell lines and in vivo in mice. Correlations between plasma neutrophil gelatinase associated lipocalin (NGAL) levels, erlotinib response and the EGFR mutational status were assessed in advanced stage NSCLC patients treated with erlotinib. Results: In 5 of 13 NSCLC cell lines NGAL was significantly upregulated. NGAL knockdown in erlotinib-resistant cells increased erlotinib sensitivity in vitro and in vivo. NGAL overexpression in erlotinib-sensitive cells augmented apoptosis resistance. This was mediated by NGAL-dependent modulation of the pro-apoptotic protein Bim levels. Evaluation of the plasma NGAL levels in NSCLC patients that received erlotinib revealed that patients with lower baseline NGAL demonstrated a better erlotinib response. Compared to patients with wild type EGFR, patients with activating EGFR mutations had lower plasma NGAL at baseline and weeks 4 and 8. Conclusions: Our studies uncover a novel mechanism of NGAL-mediated modulation of Bim levels in NSCLC that might contribute to TKI resistance in lung cancer patients. These findings provide the rationale for the further investigations of the utility of NGAL as a potential therapeutic target or diagnostic biomarker.
Lung cancer; effectors of apoptosis; survival factors; EGFR; erlotinib resistance
We hypothesize that inferior vena cava-inferior atrial ganglionated plexus nerve activity (IVC-IAGPNA) is responsible for the ventricular rate (VR) control during atrial fibrillation (AF) in ambulatory dogs.
Methods and Results
We recorded bilateral cervical vagal nerve activity (VNA) and IVC-IAGPNA during baseline sinus rhythm and during pacing-induced sustained AF in 6 ambulatory dogs. Integrated nerve activities and average VR were measured every 10-s over 24-hour periods. LVNA was associated with VR reduction during AF in 5 dogs (from 211 bpm, 95% confidence interval [CI], 186 to 233 to 178 bpm [95% CI, 145 to 210], p<0.001) and RVNA in 1 dog (208 bpm [95% CI, 197 to 223] to 181 bpm [95% CI, 163 to 200], p<0.01). There were good correlations between IVC-IAGPNA and LVNA in the former 5 dogs, and between IVC-IAGPNA and RVNA in the latter dog. IVC-IAGPNA was associated with VR reduction in all dogs studied. RVNA was associated with baseline sinus rate reduction from 105 bpm (95% CI, 95 to 116) to 77 bpm (95% CI, 64 to 91, p<0.01) in 4 dogs while LVNA was associated with sinus rate reduction from 111 bpm (95% CI, 90 to 1250) to 81 bpm (95% CI, 67 to 103, p<0.01) in 2 dogs.
IVC-IAGPNA is invariably associated with VR reduction during AF. In comparison, right or left VNA was associated with VR reduction only when it co-activates with the IVC-IAGPNA. The vagus nerve that controls VR during AF may be different than that controls sinus rhythm.
atrial fibrillation; atrioventricular node; ECG; nervous system, autonomic; ventricular rate
Myocardial infarction (MI) results in cardiac nerve sprouting in the myocardium. Whether or not similar neural remodeling occurs in the stellate ganglia (SG) is unknown. We aimed to test the hypothesis that MI induces bilateral SG nerve sprouting.
Acute MI was created by coronary artery ligation in rabbits (n=12). Serum nerve growth factor (NGF) level was measured by enzyme-linked immunosorbent assay (ELISA). The hearts and bilateral SGs were harvested for immunohistochemistry after 1 week in 6 rabbits, and after 1 month in 6 rabbits. Immunostaining for tyrosine hydroxylase (TH), growth-associated protein 43 (GAP43), cholineacetyltransferase (ChAT) and synaptophysin (SYN) was performed to determine the magnitude of nerve sprouting. Tissues from 6 normal rabbits were used as controls. Nerve density was determined by computerized morphometry.
MI results in increased serum NGF levels at 1 week (1519.8±632.2 ng/ml) that persists to 1 month (1361.2±176.3 ng/ml) as compared to controls (89.6±34.9 ng/ml), (p=.0002, and , p=.0001, respectively). Immunostaining demonstrated nerve sprouting and hyperinnervation in both SGs after MI. The nerve densities (µm2/ganglion cell) in SG 1 week after MI, 1 month after MI and in control groups, respectively, were: GAP43, 278±96, 225±39 and 149±57 (p=.01); SYN, 244±152, 268±115 and 102±60 (p=.02); TH, 233±71, 180±50 and 135±68 (p=.047); ChAT, 244±100, 208±46 and 130±41 µm2/cell (p=.01).
MI increases serum NGF levels and induces nerve sprouting and hyperinnervation in bilateral SGs for at least 1 month after MI. The hyperinnervation includes both postganglionic adrenergic axons and preganglionic cholinergic axons in the SG.
Myocardial Infarction; Ventricular Arrhythmia; Autonomic Nervous System; Stellate Ganglion; Nerve Sprouting; Sudden Cardiac Death
Kawasaki disease (KD) is the most common cause of acute vasculitis and acquired cardiac disease in US children. Untreated, children may develop coronary artery aneurysms, myocardial infarction and sudden death as a result of the illness. Up to a third of KD patients fail to respond to intravenous gammaglobulin (IVIG), the standard therapy, and alternative treatments are being investigated. Genetic studies have indicated a possible role for IL-1β in KD. We therefore explored the role of IL-1β in a murine model of KD.
Methods and Results
Using an established mouse model of KD that involves injection of Lactobacillus casei cell wall extract (LCWE), we investigated the role of IL- 1β and caspase-1 (activated by the inflammasome and required for IL-1β maturation) in coronary arteritis, and evaluated the efficacy of IL-1 receptor antagonist (IL-1Ra) as a potential treatment. LCWE-induced IL-1β maturation and secretion was dependent on the NLRP3 inflammasome in macrophages. Both caspase1-deficient and IL-1R-deficient mice were protected from LCWE-induced coronary lesions. Injection of recombinant IL-1β to caspase-1-deficient mice restored the ability of LCWE to cause coronary lesions in response to LCWE. Furthermore, daily injections of the IL-1Ra prevented LCWE-mediated coronary lesions, up to three days after LCWE injection.
Our results strongly suggest that caspase-1 and IL-1β play critical roles in the development of coronary lesions in this KD mouse model, blocked by IL-1Ra. Therefore, anti-IL-1β treatment strategies may constitute an effective, more targeted treatment of KD to prevent coronary lesions.
Calcium transient triggered firing (CTTF) is induced by large intracellular calcium (Cai) transient and short action potential duration (APD). We hypothesized that CTTF underlies the mechanisms of early afterdepolarization (EAD) and spontaneous recurrent atrial fibrillation (AF) in transgenic (Tx) mice with overexpression of transforming growth factor β1 (TGF-β1).
Methods and Results
MHC-TGFcys33ser Tx mice develop atrial fibrosis because of elevated levels of TGF-β1. We studied membrane potential and Cai transients of isolated superfused atria from Tx and wild-type (Wt) littermates. Short APD and persistently elevated Cai transients promoted spontaneous repetitive EADs, triggered activity and spontaneous AF after cessation of burst pacing in Tx but not Wt atria (39% vs. 0%, P=0.008). We were able to map optically 4 episodes of spontaneous AF re-initiation. All first and second beats of spontaneous AF originated from the right atrium (4/4, 100%), which is more severely fibrotic than the left atrium. Ryanodine and thapsigargin inhibited spontaneous re-initiation of AF in all 7 Tx atria tested. Western blotting showed no significant changes of calsequestrin or sarco/endoplasmic reticulum Ca2+-ATPase 2a.
Spontaneous AF may occur in the Tx atrium because of CTTF, characterized by APD shortening, prolonged Cai transient, EAD and triggered activity. Inhibition of Ca2+ release from the sarcoplasmic reticulum suppressed spontaneous AF. Our results indicate that CTTF is an important arrhythmogenic mechanism in TGF-β1 Tx atria.
Arrhythmia; Atrial fibrillation; Ca2+ triggers; Intracellular calcium; Optical mapping; Transgenic mice models
Estrogen signaling is critical in the progression of tumors that bear estrogen receptors. In most patients with breast cancer, inhibitors that block interactions of estrogen with its receptors or suppress the production of endogenous estrogens are important interventions in the clinic. Recent evidence now suggests that estrogen also contributes to the pathogenesis of non–small cell lung cancer (NSCLC). We used a human lung cancer xenograph model system to analyze the effect of aromatase or estradiol on tumor growth. We further examined the level of protein expression of aromatase in 422 patients with NSCLC using a high-density tissue microarray. Results were confirmed and validated on an independent patient cohort (n = 337). Lower levels of aromatase predicted a greater chance of survival in women 65 years and older. Within this population, the prognostic value of aromatase was greatest in earlier stage lung cancer (stage I/II). In addition, for women with no history of smoking, lower aromatase levels were a strong predictor of survival. Our findings implicate aromatase as an early-stage predictor of survival in some women with NSCLC. We predict that women whose lung cancers have higher levels of aromatase might be good candidates for targeted treatment with aromatase inhibitors.
The goal of this study was to determine whether antidonor antibodies directed against human leukocyte antigen (HLA) or endothelial cells (ECs) expressed antigens, including major histocompatibility complex class I chain-related antigens A (MICA) are associated with the diagnosis of antibody-mediated rejection (AMR) in heart transplant recipients.
We studied posttransplant antidonor HLA antibodies in 168 heart allograft recipients transplanted from October 2001 to December 2005. Among them, there were 37 AMR + patients and 131 age- and sex- matched AMR − controls. Sera were collected at the time of protocol biopsies and tested for the presence of HLA antibodies. Seventy-two of the 168 patients were genotyped for donor and recipient MICA alleles and were tested for the presence of anti-MICA antibodies. Thirty-one patients who never developed antibodies to HLA or MICA were further tested for anti-EC antibodies.
Results and Conclusions
Of 37 AMR + patients, 22 (60%) developed donor-specific antibodies (DSA) to HLA compared with 6 of 131(4%) AMR − patients (P<0.0001). Of the remaining 15 AMR + patients, 5 had anti-HLA antibodies that were not donor specific and 10 did not show any HLA antibodies. In the subgroup of 72 patients, all 19 AMR + patients had clearly demonstrable antibodies reactive with donor HLA, MICA or with nondonor-derived ECs, with 30% of them showed antibodies directed to non-HLA antigens. The incidence of transplant coronary artery disease was significantly higher in patients who had DSA to HLA and MICA compared with patients without DSA.
Non-HLA antibody; MICA; Endothelial cell antibody; HLA antibody; Antibody-medicated rejection; Chronic rejection
Purpose of review
The autonomic nerve system is a potentially potent modulator of the initiation and perpetuation of atrial fibrillation (AF). This review will briefly summarize the neural mechanisms of AF.
Complex interactions exist between the sympathetic and parasympathetic nervous system on the atrial electrophysiologic properties. Direct autonomic recordings in canine models demonstrated simultaneous sympathovagal discharges are the most common triggers of paroxysmal atrial tachycardia and paroxysmal AF. Also, intrinsic cardiac autonomic nerve can serve as a sole triggering factor for the initiation of AF. Modulation of autonomic nervous system (ANS) by electrical stimulation has been tried as a treatment strategy clinically and experimentally. Recent studies showed that autonomic nervous system modulation can suppress the stellate ganglion nerve activity and reduce the incidence of paroxysmal atrial tachyarrhythmias in ambulatory dogs.
The autonomic nerve system influences the initiation and perpetuation of AF. Scientific advances toward a better understanding of the complex interrelationships of the various components of the ANS will hopefully lead to improvement of treatments for this common arrhythmia.
Autonomic nerve; atrial fibrillation; vagal nerve stimulation
Estrogen signaling pathways may play a significant role in the pathogenesis of non-small cell lung cancers (NSCLC) as evidenced by the expression of aromatase and estrogen receptors (ERα and ERβ) in many of these tumors. Here we examine whether ERα and ERβ levels in conjunction with aromatase define patient groups with respect to survival outcomes and possible treatment regimens. Immunohistochemistry was performed on a high-density tissue microarray with resulting data and clinical information available for 377 patients. Patients were subdivided by gender, age and tumor histology, and survival data was determined using the Cox proportional hazards model and Kaplan-Meier curves. Neither ERα nor ERβ alone were predictors of survival in NSCLC. However, when coupled with aromatase expression, higher ERβ levels predicted worse survival in patients whose tumors expressed higher levels of aromatase. Although this finding was present in patients of both genders, it was especially pronounced in women ≥ 65 years old, where higher expression of both ERβ and aromatase indicated a markedly worse survival rate than that determined by aromatase alone. Conclusion: Expression of ERβ together with aromatase has predictive value for survival in different gender and age subgroups of NSCLC patients. This predictive value is stronger than each individual marker alone. Our results suggest treatment with aromatase inhibitors alone or combined with estrogen receptor modulators may be of benefit in some subpopulations of these patients.
NSCLC; tissue microarray; aromatase; estrogen receptor; immunohistochemistry; prognosis
Matrix metalloproteinase (MMP) -2 and -9 play important roles in the progression of atherosclerosis. This study aims to determine whether MMP-2 and -9 content in the fibrotic caps of atherosclerotic plaque is correlated with plaque autofluorescence. A time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) system was used to measure the autofluorescence and assess the biochemical composition of human plaques obtained from carotid endarterectomy. Results presented here demonstrate for the first time the ability to characterize the biochemical composition as it relates to MMP-2 and -9 content in the atherosclerotic plaque cap using a label-free imaging technique implemented with a fiberoptic TR-LIFS system.
Matrix metalloproteinases; time-resolved fluorescence spectroscopy; atherosclerosis; carotid plaque
Ample studies suggest that the cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) pathway plays a pivotal role in carcinogenesis and that COX-2 inhibition may help prevent lung cancer. Therefore, we conducted a randomized, double-blind, placebo-controlled trial of the COX-2 selective inhibitor celecoxib (400 mg bid for 6 months) in former-smokers (age ≥45, ≥30 pack-years of smoking, ≥1 year of sustained abstinence from smoking). We assessed the impact of celecoxib on cellular and molecular events associated with lung cancer pathogenesis; the primary endpoint was bronchial Ki-67 labeling index (Ki-67 LI). Of 137 randomized subjects, 101 completed both baseline and 6-month bronchoscopies and were evaluable for the primary endpoint analysis. The beneficial effect on Ki-67 LI was greater in the celecoxib arm (versus placebo) in a mixed-effects analysis (P = 0.0006), and celecoxib significantly decreased Ki-67 LI by an average of 34%, whereas placebo increased Ki-67 LI by an average of 3.8% (P = 0.04; t-test). Participants crossed over to the other study arm at 6 months. Therefore, at 12 months all remaining participants had received 6 months of celecoxib, and their decreases in Ki-67 LI correlated with a reduction and/or resolution of lung nodules on computed tomography. Celecoxib significantly reduced plasma c-reactive protein and interleukin-6 mRNA and protein and increased 15(S)-hydroxy-eicosatetraenoic acid levels in BAL samples. The baseline ratio of COX-2 to 15-hydroxyprostaglandin dehydrogenase mRNA in bronchoalveolar lavage (BAL) cells was a significant predictive marker of Ki-67 response to celecoxib (P = 0.002). Our collective findings support the continued investigation of celecoxib for lung cancer chemoprevention in former smokers at a low risk of cardiovascular disease.
COX-2; 15-PGDH; PGE2; CRP; IL-6; 15-HETE
We hypothesize that left sided low-level vagus nerve stimulation (LL-VNS) can suppress sympathetic outflow and reduce atrial tachyarrhythmias in ambulatory dogs.
Methods and Results
We implanted in 12 dogs a neurostimulator to stimulate left cervical vagus nerve and a radiotransmitter for continuous recording of left stellate ganglion nerve activities (SGNA), vagal nerve activities (VNA) and electrocardiograms. Group 1 dogs (N=6) underwent 1 week continuous LL-VNS. Group 2 dogs (N=6) underwent intermittent rapid atrial pacing followed by active or sham LL-VNS on alternate weeks. Integrated SGNA was significantly reduced during LL-VNS (7.8 mV-s; 95% confidence interval [CI] 6.94 to 8.66] vs. 9.4 mV-s [CI, 8.5 to 10.3] at baseline, P=0.033) in Group 1.The reduction was most apparent at 8 AM, along with a significantly reduced heart rate (P=0.008). LL-VNS did not change VNA. The density of tyrosine hydroxylase-positive nerves in the left stellate ganglion one week after cessation of LL-VNS were 99684 µm2/mm2 (CI, 28850 to 170517) in LL-VNS dogs and 186561 µm2/ mm2 (CI, 154956 to 218166; P=0.008) in normal dogs. In Group 2, the frequencies of paroxysmal atrial fibrillation and tachycardia during active LL-VNS were 1.4/day (CI, 0.5/day to 5.1/day) and 8.0/day (CI, 5.3/day to 12.0/day), respectively, significantly lower than during sham stimulation (9.2/day [CI, 5.3/day to 13.1/day], P=0.001 and 22.0/day [CI, 19.1/day to 25.5/day], P<0.001, respectively).
LL-VNS suppresses SGNA and reduces the incidences of paroxysmal atrial tachyarrhythmias in ambulatory dogs. Significant neural remodeling of the left stellate ganglion is evident one week after cessation of chronic LL-VNS.
nervous system, autonomic; vagal stimulation; tachyarrhythmias; atrial fibrillation
FK506 binding protein 12 (FKBP12) is a known cis-trans peptidyl prolyl isomerase and highly expressed in the heart. Its role in regulating postnatal cardiac function remains largely unknown.
Methods and Results
We generated FKBP12 overexpressing transgenic (αMyHC-FKBP12) mice and cardiomyocyte-restricted FKBP12 conditional knockout (FKBP12f/f/αMyHC-Cre) mice, and analyzed their cardiac electrophysiology in vivo and in vitro. A high incidence (38%) of sudden death was found in αMyHC-FKBP12 mice. Surface and ambulatory ECGs documented cardiac conduction defects, which were further confirmed by electrical measurements and optical mapping in Langendorff-perfused hearts. αMyHC-FKBP12 hearts had slower action potential upstrokes, and longer action potential durations. Whole-cell patch-clamp analyses demonstrated an ~80% reduction in peak density of the tetrodotoxin-resistant, voltage-gated sodium current, INa, in αMyHC-FKBP12 ventricular cardiomyocytes, a slower recovery of INa from inactivation, shifts of steady-state activation and inactivation curves of INa to more depolarized potentials, and augmentation of late INa, suggesting that the arrhythmogenic phenotype of αMyHC-FKBP12 mice is due to abnormal INa. Ventricular cardiomyocytes isolated from FKBP12f/f/αMyHC-Cre hearts showed faster action potential upstrokes and a more than 2-fold increase in peak INa density. Dialysis of exogenous recombinant FKBP12 protein into FKBP12-deficient cardiomyocytes promptly recapitulated alterations in INa seen in αMyHC-FKBP12 myocytes.
FKBP12 is a critical regulator of INa and is important to cardiac arrhythmogenic physiology. FKPB12-mediated dysregulation of INa may underlie clinical arrhythmias associated with FK506 administration.
proteins; ion channels; conduction; heart block; long-QT syndrome
We tested the hypothesis that heart failure (HF) results in right atrial ganglionated plexus (RAGP) denervation which contributes to sinoatrial node dysfunction.
HF is associated with sinoatrial node dysfunction. However, the detailed mechanisms remain unclear.
We recorded nerve activity (NA) from the RAGP, right stellate ganglion (SG) and right vagal nerve in 7 ambulatory dogs at baseline and after pacing-induced HF. We also determined the effects of RAGP stimulation in isolated normal and HF canine right atria (RA).
Nerve activities in both the SG and vagal were significantly higher in HF than at baseline. The relationship between 1-min integrated nerve activities of vagal and RAGP showed either a positive linear correlation (Group 1, n=4) or an L-shaped correlation (Group 2, n=3). In all dogs, a reduced heart rate was observed when vagal-NA was associated with simultaneously increased RAGP-NA. On the other hand, when vagal-NA was not associated with increased RAGP-NA, the heart rate was not reduced. The induction of HF significantly decreased RAGP-NA in all dogs (P<0.05). Stimulating the superior RAGP in isolated right atrium significantly reduced the sinus rate in normal but not the HF hearts. Immunohistochemical staining revealed lower densities of tyrosine hydroxylase and choline acetyltransferase -positive nerve tissues in HF RAGP than normal (P<0.001 and P=0.001, respectively).
The RAGP nerve activity is essential for the vagal nerve to counterbalance the stellate ganglion in sinus rate control. In heart failure, RAGP denervation and decreased RAGP nerve activity contribute to the sinus node dysfunction.
heart failure; nervous system; autonomic; sinoatrial node
The presence of epicardial fat can confound the quantification of scar during transpericardial electroanatomic mapping. The electrogram (EGM) characteristics of epicardial fat have not been systematically compared with infarct scar using gross and histopathologic analysis as a gold standard.
A closed-chest infarction was created in 40–50 kg pigs by occlusion of the circumflex artery for 150 minutes using an angioplasty balloon. This artery was chosen to minimize any potential overlap of epicardial fat with infarct and to spare any septal involvement. After 4–12 weeks of infarct healing, epicardial mapping was performed. EGMs in low voltage regions (<1.5mV) were analyzed and bipolar amplitude, duration, number of deflections, and the presence of late potentials were recorded. Statistical analysis was performed using unpaired t-test and chi square analysis. Gross and histopathologic examination was used to confirm areas of fat and infarct scar.
Seven porcine hearts were analyzed after high-density epicardial mapping (364±92 points) was performed 48±19 days after infarction. The mean bipolar EGM amplitude was similar in fat and scar (0.77±0.34 vs 0.75±0.38mV; P=NS). The mean EGM duration was longer in scar than fat (68.8±18.9 vs 50.1±11.6 ms; P<0.0001) and exhibited more fractionation (8.5±3.1 vs 4.7±1.8 deflections; P<0.0001). The presence of late potentials was 99% specific for scar. Further, areas of fat >4 mm in thickness registered low voltage bipolar EGMs.
Scar from healed myocardial infarction exhibits more fractionation and longer EGM duration when compared to fat. Late potentials are highly specific for locating infarct scars.
Epicardial; fat; infarction; electrogram; late potential
Lung involvement is the leading cause of death in systemic sclerosis (SSc), however lung transplantation (LT) for systemic disease remains controversial. Our objective was to comprehensively evaluate post-LT outcomes for SSc compared to idiopathic pulmonary fibrosis (IPF).
We retrospectively evaluated bilateral LT recipients (LTR) with SSc or IPF at our center between 1/1/2003 and 12/31/2007. The primary endpoint was all-cause mortality at 1 year post-LT. Secondary endpoints included assessments of acute rejection (AR), pulmonary function, infection, and chronic rejection.
14 patients with SSc and 38 patients with IPF underwent LT. Apart from a younger SSc cohort (53.2 vs. 58.8 years, p=0.02), the two groups were well matched. One year all-cause mortality was no different between SSc (6.6%) and IPF (13.1%) groups, after adjusting for age (p=0.62). Rates of AR ≥ 2 were significantly increased for the SSc compared to the IPF group (HR 2.91; p=0.007). Other endpoints including chronic rejection, infection, and pulmonary function showed no differences.
SSc LTR experience similar survival 1 year post-LT when compared to IPF. AR rates may be significantly higher in the SSc group. Longer follow-up is necessary to determine the effects of gastrointestinal dysfunction and AR on late allograft function in SSc LTR.
lung transplantation; systemic sclerosis
The complete removal of the cardiac sodium-calcium exchanger (NCX1) is associated with embryonic lethality while its overexpression is linked to heart failure. To determine whether or not a reduced expression of NCX1 is compatible with normal heart structure and function, we studied two knockout mouse models with reduced levels of NCX1: a heterozygous global knockout (HG-KO) with a 50% level of NCX1 expression in all myocytes, and a ventricular specific KO (V-KO) with NCX1 expression in only 10-20% of the myocytes.
Methods and Results
Both groups of mice were evaluated at baseline, after trans-aortic constriction (TAC), and after acute or chronic beta-adrenergic stimulation. At baseline, the HG-KO mice had smaller hearts and the V-KO mice had larger hearts than their wild-type (WT) controls (P<0.05). The HG-KO and their control WT mice had normal responses to TAC and beta-adrenergic stimulation. However, the V-KO group was intolerant to TAC and had a significantly (P<0.05) blunted response to beta-adrenergic stimulation as compared to the HG-KO mice and WT controls. Unlike the HG-KO mice, the V-KO mice did not tolerate chronic isoproterenol infusion. Telemetric analysis of the ECG, body temperature and activity revealed a normal diurnal rhythm in all groups of mice, but confirmed shorter QT intervals along with increased arrhythmias and reduced R/P amplitude ratios in the V-KO mice.
Though NCX1 can be reduced by ½ in all myocytes without significant functional alterations, it must be expressed in more than 20% of the myocytes to prevent severe remodeling and heart failure in mouse heart.
Heart Failure; Hypertrophy; Ventricular Dysfunction; Knock-out Mice
Detection of atherosclerotic plaque vulnerability has critical clinical implications for avoiding sudden death in patients with high risk of plaque rupture. We report on multimodality imaging of ex-vivo human carotid plaque samples using a system that integrates fluorescence lifetime imaging (FLIM), ultrasonic backscatter microscopy (UBM), and photoacoustic imaging (PAI). Biochemical composition is differentiated with a high temporal resolution and sensitivity at the surface of the plaque by the FLIM subsystem. 3D microanatomy of the whole plaque is reconstructed by the UBM. Functional imaging associated with optical absorption contrast is evaluated from the PAI component. Simultaneous recordings of the optical, ultrasonic, and photoacoustic data present a wealth of complementary information concerning the plaque composition, structure, and function that are related to plaque vulnerability. This approach is expected to improve our ability to study atherosclerotic plaques. The multimodal system presented here can be translated into a catheter based intraluminal system for future clinical studies.
(170.6510) Spectroscopy, tissue diagnostics; (300.6500) Spectroscopy, time-resolved; (110.7170) Ultrasound; (170.5120) Photoacoustic imaging; (170.6935) Tissue characterization
Little is known about the relationship between intrinsic cardiac nerve activity (ICNA) and spontaneous arrhythmias in ambulatory animals.
Methods and Results
We implanted radiotransmitters to record extrinsic cardiac nerve activity (ECNA, including stellate ganglion nerve activity, SGNA; vagal nerve activity, VNA) and ICNA (including superior left ganglionated plexi nerve activity, SLGPNA; ligament of Marshall nerve activity, LOMNA) in 6 ambulatory dogs. Intermittent rapid left atrial pacing was performed to induce paroxysmal atrial fibrillation (PAF) or atrial tachycardia (PAT). The vast majority (94%) of LOMNA were preceded or co-activated with ECNA (SGNA or VNA), whereas 6% of episodes were activated alone without concomitant SGNA or VNA. PAF and PAT were invariably (100%) preceded (<5 s) by ICNA. Most of PAT events (89%) were preceded by ICNA and sympathovagal co-activation, whereas 11% were preceded by ICNA and SGNA-only activation. Most of PAF events were preceded only by ICNA (72%); the remaining 28% by ECNA and ICNA together. Complex fractionated atrial electrograms (CFAEs) were observed during ICNA discharges that preceded the onset of PAT and PAF. Immunostaining confirmed the presence of both adrenergic and cholinergic nerve at ICNA sites.
There is a significant temporal relationship between ECNA and ICNA. However, ICNA can also activate alone. All PAT and PAF episodes were invariably preceded by ICNA. These findings suggest that ICNA (either alone or in collaboration with ECNA) is an invariable trigger of paroxysmal atrial tachyarrhythmias. ICNA might contaminate local atrial electrograms, resulting in CFAE-like activity.
nervous system; autonomic; atrium; arrhythmia; ligament of Marshall