Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation FASEB JOURNAL 2016; 30 (4): 1464-1479
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a powerful platform for uncovering disease mechanisms and assessing drugs for efficacy/toxicity. However, the accuracy with which hiPSC-CMs recapitulate the contractile and remodeling signaling of adult cardiomyocytes is not fully known. We used -adrenergic receptor (-AR) signaling as a prototype to determine the evolution of signaling component expression and function during hiPSC-CM maturation. In "early" hiPSC-CMs (less than or equal to d 30), 2-ARs are a primary source of cAMP/PKA signaling. With longer culture, 1-AR signaling increases: from 0% of cAMP generation at d 30 to 56.8 6.6% by d 60. PKA signaling shows a similar increase: 15.7 5.2% (d 30), 49.8 0.5% (d 60), and 71.0 6.1% (d 90). cAMP generation increases 9-fold from d 30 to 60, with enhanced coupling to remodeling pathways (e.g., Akt and Ca(2+)/calmodulin-dependent protein kinase type II) and development of caveolin-mediated signaling compartmentalization. By contrast, cardiotoxicity induced by chronic -AR stimulation, a major component of heart failure, develops much later: 5% cell death at d 30 vs. 55% at d 90. Moreover, -AR maturation can be accelerated by biomechanical stimulation. The differential maturation of -AR functional vs. remodeling signaling in hiPSC-CMs has important implications for their use in disease modeling and drug testing. We propose that assessment of signaling be added to the indices of phenotypic maturation of hiPSC-CMs.-Jung, G., Fajardo, G., Ribeiro, A. J. S., Kooiker, K. B., Coronado, M., Zhao, M., Hu, D.-Q., Reddy, S., Kodo, K., Sriram, K., Insel, P. A., Wu, J. C., Pruitt, B. L., Bernstein, D. Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation.
View details for DOI 10.1096/fj.15-280982
View details for Web of Science ID 000372629100009
Molecular Mechanisms of Right Ventricular Failure. Circulation 2015; 132 (18): 1734-1742
An abundance of data has provided insight into the mechanisms underlying the development of left ventricular (LV) hypertrophy and its progression to LV failure. In contrast, there is minimal data on the adaptation of the right ventricle (RV) to pressure and volume overload and the transition to RV failure. This is a critical clinical question, because the RV is uniquely at risk in many patients with repaired or palliated congenital heart disease and in those with pulmonary hypertension. Standard heart failure therapies have failed to improve function or survival in these patients, suggesting a divergence in the molecular mechanisms of RV versus LV failure. Although, on the cellular level, the remodeling responses of the RV and LV to pressure overload are largely similar, there are several key differences: the stressed RV is more susceptible to oxidative stress, has a reduced angiogenic response, and is more likely to activate cell death pathways than the stressed LV. Together, these differences could explain the more rapid progression of the RV to failure versus the LV. This review will highlight known molecular differences between the RV and LV responses to hemodynamic stress, the unique stressors on the RV associated with congenital heart disease, and the need to better understand these molecular mechanisms if we are to develop RV-specific heart failure therapeutics.
View details for DOI 10.1161/CIRCULATIONAHA.114.012975
View details for PubMedID 26527692
The vulnerable right ventricle. Current opinion in pediatrics 2015; 27 (5): 563-568
The right ventricle (RV) is uniquely at risk in many patients with repaired or palliated congenital heart disease (CHD) such as tetralogy of Fallot, corrected transposition, single right ventricle, and in those with pulmonary hypertension. These patients live with abnormal cardiac loading conditions throughout their life, predisposing them to right heart failure.Standard heart failure therapies, developed to treat left ventricular failure, have failed to improve function or survival in patients with RV failure, suggesting a divergence in the molecular mechanisms of right versus left ventricular failure. As surgical techniques for repair of the most complex forms of RV-affecting CHDs continue to improve, more children with CHD will survive into adulthood. Long-term survival and quality of life will ultimately depend on our ability to preserve RV function.The purpose of this review is to highlight the differences between the right and left ventricular responses to stress, our current knowledge of how the RV adapts to the unique hemodynamic stressors experienced by patients with CHD, and the need to better understand the molecular mechanisms of RV failure, providing new targets for the development of RV-specific heart failure therapeutics.
View details for DOI 10.1097/MOP.0000000000000268
View details for PubMedID 26262580
BMPR2 Preserves Mitochondrial Function and DNA during Reoxygenation to Promote Endothelial Cell Survival and Reverse Pulmonary Hypertension CELL METABOLISM 2015; 21 (4): 596-608
Mitochondrial dysfunction, inflammation, and mutant bone morphogenetic protein receptor 2 (BMPR2) areassociated with pulmonary arterial hypertension (PAH), an incurable disease characterized by pulmonary arterial (PA) endothelial cell (EC) apoptosis, decreased microvessels, and occlusive vascular remodeling. We hypothesized that reduced BMPR2 induces PAEC mitochondrial dysfunction, promoting a pro-inflammatory or pro-apoptotic state. Mice with EC deletion of BMPR2 develop hypoxia-induced pulmonary hypertension that, in contrast to non-transgenic littermates, does not reverse upon reoxygenation and is associated with reduced PA microvessels and lung EC p53, PGC1 and TFAM, regulators of mitochondrial biogenesis, and mitochondrial DNA. Decreasing PAEC BMPR2 by siRNA during reoxygenation represses p53, PGC1, NRF2, TFAM, mitochondrial membrane potential, and ATP and induces mitochondrial DNA deletion and apoptosis. Reducing PAEC BMPR2 in normoxia increases p53, PGC1, TFAM, mitochondrial membrane potential, ATP production, and glycolysis, and induces mitochondrial fission and a pro-inflammatory state. These features are recapitulated in PAECs from PAH patients with mutant BMPR2.
View details for DOI 10.1016/j.cmet.2015.03.010
View details for Web of Science ID 000352500800014
Adrenergic receptor genotype influences heart failure severity and beta-blocker response in children with dilated cardiomyopathy Open PEDIATRIC RESEARCH 2015; 77 (2): 363-369
Adrenergic receptor (ADR) genotypes are associated with heart failure (HF) and -blocker response in adults. We assessed the influence of ADR genotypes in children with dilated cardiomyopathy (DCM).Ninety-one children with advanced DCM and 44 with stable DCM were genotyped for three ADR genotypes associated with HF risk in adults: 2cdel322-325, 1Arg389, and 2Arg16. Data were analyzed by genotype and -blocker use. Mean age at enrollment was 8.5 y.One-year event-free survival was 51% in advanced and 80% in stable DCM. High-risk genotypes were associated with higher left ventricular (LV) filling pressures, higher systemic and pulmonary vascular resistance, greater decline in LV ejection fraction (P < 0.05), and a higher frequency of mechanical circulatory support while awaiting transplant (P = 0.05). While -blockers did not reduce HF severity in the overall cohort, in the subset with multiple high-risk genotypes, those receiving -blockers showed better preservation of cardiac function and hemodynamics compared with those not receiving -blockers (interaction P < 0.05).Our study identifies genetic risk markers that may help in the identification of patients at risk for developing decompensated HF and who may benefit from early institution of -blocker therapy before progression to decompensated HF.
View details for DOI 10.1038/pr.2014.183
View details for Web of Science ID 000348268200012
Variability of characteristics and outcomes following cardiopulmonary resuscitation events in diverse ICU settings in a single, tertiary care children's hospital*. Pediatric critical care medicine 2014; 15 (3): e128-41
The primary objective of this study was to compare and contrast the characteristics and survival outcomes of cardiopulmonary resuscitation for "monitored" events in pediatric patients treated with chest compressions more than or equal to 1 minute in varied ICU settings.Retrospective observational study.Three different specialized ICUs in a single, tertiary care, academic children's hospital.We collected demographic information, preexisting conditions, preevent characteristics, event characteristics, and outcome data. The primary outcome measure was survival to hospital discharge. Secondary outcome measures included return of spontaneous circulation, 24-hour survival, and survival with good neurologic outcome.None.Four hundred eleven patients treated with chest compressions for more than or equal to 1 minute were included in the analysis: 170 patients were located in the cardiovascular ICU, 157 patients in the neonatal ICU, and 84 patients in the PICU. Arrest durations were longer in the cardiovascular ICU than other ICUs. Use of extracorporeal cardiopulmonary resuscitation was more prevalent in the cardiovascular ICU (cardiovascular ICU, 17%; neonatal ICU, 3%; PICU, 4%). Return of spontaneous circulation, 24-hour survival, survival to hospital discharge, and good neurologic outcome were highest among neonatal ICU patients (survival to discharge, 53%) followed by cardiovascular ICU patients (survival to discharge, 46%) and PICU patients (survival to discharge, 36%). In a multivariable model controlling for patient and event characteristics, using cardiovascular ICU as reference, adjusted odds of survival in PICU were 0.33 (95% CI, 0.14-0.76; p = 0.009) and odds of survival in neonatal ICU were 0.80 (95% CI, 0.31-2.11; p = 0.65).Comparative analysis of pediatric patients undergoing cardiopulmonary resuscitation in three different ICU settings demonstrated a significant variation in baseline, preevent, and event characteristics. Although outcomes vary significantly among the three different ICUs, it was difficult to ascertain if this difference was due to variation in the disease process or variation in the location of the patient.
View details for DOI 10.1097/PCC.0000000000000067
View details for PubMedID 24413318
Atherosclerosis Causing Recurrent Catastrophic Aortopulmonary Shunt Dehiscence in a Patient with Alagille Syndrome PEDIATRIC CARDIOLOGY 2013; 34 (8): 1945-1948
Alagille syndrome (ALGS) is an autosomal dominant disorder associated with cholestatic liver disease, pulmonary valvar stenosis or atresia, vasculopathy, and renal disease. Although the liver and cardiac manifestations contribute to overall morbidity and mortality during their life span, these patients also carry a burden of important but often underappreciated vascular abnormalities. This report describes a 3year-old girl with Alagille syndrome, hepatic cholestasis, systemic hypertension, hypercholesterolemia, hypertriglyceridemia, and tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collaterals (TOF/PA/MAPCAs). She presented for bilateral pulmonary artery plasty and central shunt upsizing. She then experienced three shunt dehiscence episodes, necessitating emergent intervention. Autopsy showed diffuse atherosclerosis and significant atherosclerotic plaque at the site of shunt dehiscence. This is the first reported case of ALGS with TOF/PA/MAPCAs and catastrophic shunt dehiscence due to significant generalized vasculopathy caused by dyslipidemia and atherosclerosis. Dyslipidemia, a known comorbidity in ALGS, is one of few modifiable risk factors that should be screened for and treated, particularly before cardiac surgery.
View details for DOI 10.1007/s00246-012-0484-4
View details for Web of Science ID 000327065100039
Deletion of the beta 2-adrenergic receptor prevents the development of cardiomyopathy in mice JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY 2013; 63: 155-164
Beta adrenergic receptor (-AR) subtypes act through diverse signaling cascades to modulate cardiac function and remodeling. Previous in vitro studies suggest that 1-AR signaling is cardiotoxic whereas 2-AR signaling is cardioprotective, and may be the case during ischemia/reperfusion in vivo. The objective of this study was to assess whether 2-ARs also play a cardioprotective role in the pathogenesis of non-ischemic forms of cardiomyopathy. To dissect the role of 1 vs 2-ARs in modulating MLP (Muscle LIM Protein) cardiomyopathy, we crossbred MLP-/- with 1-/- or 2-/- mice. Deletion of the 2-AR improved survival, cardiac function, exercise capacity and myocyte shortening; by contrast haploinsufficency of the 1-AR reduced survival. Pathologic changes in Ca(2+) handling were reversed in the absence of 2-ARs: peak Ca(2+) and SR Ca(2+) were decreased in MLP-/- and 1+/-/MLP-/- but restored in 2-/-MLP-/-. These changes were associated with reversal of alterations in troponin I and phospholamban phosphorylation. Gi inhibition increased peak and baseline Ca(2+), recapitulating changes observed in the 2-/-/MLP-/-. The L-type Ca(2+) blocker verapamil significantly decreased cardiac function in 2-/-MLP-/- vs WT. We next tested if the protective effects of 2-AR ablation were unique to the MLP model using TAC-induced heart failure. Similar to MLP, 2-/- mice demonstrated delayed progression of heart failure with restoration of myocyte shortening and peak Ca(2+) and Ca(2+) release. Deletion of 2-ARs prevents the development of MLP-/- cardiomyopathy via positive modulation of Ca(2+) due to removal of inhibitory Gi signaling and increased phosphorylation of troponin I and phospholamban. Similar effects were seen after TAC. Unlike previous models where 2-ARs were found to be cardioprotective, in these two models, 2-AR signaling appears to be deleterious, potentially through negative regulation of Ca(2+) dynamics.
View details for DOI 10.1016/j.yjmcc.2013.07.016
View details for Web of Science ID 000325387300017
View details for PubMedID 23920331
FK506 activates BMPR2, rescues endothelial dysfunction, and reverses pulmonary hypertension. journal of clinical investigation 2013; 123 (8): 3600-3613
Dysfunctional bone morphogenetic protein receptor-2 (BMPR2) signaling is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). We used a transcriptional high-throughput luciferase reporter assay to screen 3,756 FDA-approved drugs and bioactive compounds for induction of BMPR2 signaling. The best response was achieved with FK506 (tacrolimus), via a dual mechanism of action as a calcineurin inhibitor that also binds FK-binding protein-12 (FKBP12), a repressor of BMP signaling. FK506 released FKBP12 from type I receptors activin receptor-like kinase 1 (ALK1), ALK2, and ALK3 and activated downstream SMAD1/5 and MAPK signaling and ID1 gene regulation in a manner superior to the calcineurin inhibitor cyclosporine and the FKBP12 ligand rapamycin. In pulmonary artery endothelial cells (ECs) from patients with idiopathic PAH, low-dose FK506 reversed dysfunctional BMPR2 signaling. In mice with conditional Bmpr2 deletion in ECs, low-dose FK506 prevented exaggerated chronic hypoxic PAH associated with induction of EC targets of BMP signaling, such as apelin. Low-dose FK506 also reversed severe PAH in rats with medial hypertrophy following monocrotaline and in rats with neointima formation following VEGF receptor blockade and chronic hypoxia. Our studies indicate that low-dose FK506 could be useful in the treatment of PAH.
View details for DOI 10.1172/JCI65592
View details for PubMedID 23867624
Altered ubiquitin-proteasome signaling in right ventricular hypertrophy and failure AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY 2013; 305 (4): H551-H562
Alterations in the ubiquitin-proteasome system (UPS) have been described in left ventricular hypertrophy and failure, although results have been inconsistent. The role of the UPS in right ventricular (RV) hypertrophy (RVH) and RV failure (RVF) is unknown. Given the greater percent increase in RV mass associated with RV afterload stress, as present in many congenital heart lesions, we hypothesized that alterations in the UPS could play an important role in RVH/RVF. UPS expression and activity were measured in the RV from mice with RVH/RVF secondary to pulmonary artery constriction (PAC). Epoxomicin and MG132 were used to inhibit the proteasome, and overexpression of the 11S PA28 subunit was used to activate the proteasome. PAC mice developed RVH (109.3% increase in RV weight to body weight), RV dilation with septal shift, RV dysfunction, and clinical RVF. Proteasomal function (26S 5 chymotrypsin-like activity) was decreased 26% (P < 0.05). Protein expression of 19S subunit Rpt5 (P < 0.05), UCHL1 deubiquitinase (P < 0.0001), and Smurf1 E3 ubiquitin ligase (P < 0.01) were increased, as were polyubiquitinated proteins (P < 0.05) and free-ubiquitins (P = 0.05). Pro-apoptotic Bax was increased (P < 0.0001), whereas anti-apoptotic Bcl-2 decreased (P < 0.05), resulting in a sixfold increase in the Bax/Bcl-2 ratio. Proteasomal inhibition did not accelerate RVF. However, proteasome enhancement by cardiac-specific proteasome overexpression partially improved survival. Proteasome activity is decreased in RVH/RVF, associated with upregulation of key UPS regulators and pro-apoptotic signaling. Enhancement of proteasome function partially attenuates RVF, suggesting that UPS dysfunction contributes to RVF.
View details for DOI 10.1152/ajpheart.00771.2012
View details for Web of Science ID 000323549500011
View details for PubMedID 23729213
Physiologic and molecular characterization of a murine model of right ventricular volume overload. American journal of physiology. Heart and circulatory physiology 2013; 304 (10): H1314-27
Pulmonary insufficiency (PI) is a common long-term sequel after repair of tetralogy of Fallot, causing progressive right ventricular (RV) dilation and failure. We describe the physiologic and molecular characteristics of the first murine model of RV volume overload. PI was created by entrapping the pulmonary valve leaflets with sutures. Imaging, catheterization, and exercise testing were performed at 1, 3, and 6 mo and compared with sham controls. RNA from the RV free wall was hybridized to Agilent whole genome oligonucleotide microarrays. Volume overload resulted in RV enlargement, decreased RV outflow tract shortening fraction at 1 mo followed by normalization at 3 and 6 mo (39 2, 44 2, and 41 2 vs. 46 3% in sham), early reversal of early and late diastolic filling velocities (E/A ratio) followed by pseudonormalization (0.87 0.08, 0.82 0.08, and 0.96 0.08 vs. 1.04 0.03; P < 0.05), elevated end-diastolic pressure (7.6 0.7, 6.9 0.8, and 7 0.5 vs. 2.7 0.2 mmHg; P < 0.05), and decreased exercise duration (26 0.4, 26 1, and 22 1.3 vs. 30 1.1 min; P < 0.05). Subendocardial RV fibrosis was evident by 1 mo. At 1 mo, 372 genes were significantly downregulated. Mitochondrial pathways and G protein-coupled receptor signaling were the most represented categories. At 3 mo, 434 genes were upregulated and 307 downregulated. While many of the same pathways continued to be downregulated, TNF-, transforming growth factor-1 (TGF-1), p53-signaling, and extracellular matrix (ECM) remodeling transitioned from down- to upregulated. We describe a novel murine model of chronic RV volume overload recapitulating aspects of the clinical disease with gene expression changes suggesting early mitochondrial bioenergetic dysfunction, enhanced TGF- signaling, ECM remodeling, and apoptosis.
View details for DOI 10.1152/ajpheart.00776.2012
View details for PubMedID 23504182
Physiologic and molecular characterization of a murine model of right ventricular volume overload AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY 2013; 304 (10): H1314-H1327
Hypoxia-Inducible Factor-1 alpha in Pulmonary Artery Smooth Muscle Cells Lowers Vascular Tone by Decreasing Myosin Light Chain Phosphorylation CIRCULATION RESEARCH 2013; 112 (9): 1230-U73
Dynamic microRNA expression during the transition from right ventricular hypertrophy to failure PHYSIOLOGICAL GENOMICS 2012; 44 (10): 562-575
MicroRNAs (miRs) are small, noncoding RNAs that are emerging as crucial regulators of cardiac remodeling in left ventricular hypertrophy (LVH) and failure (LVF). However, there are no data on their role in right ventricular hypertrophy (RVH) and failure (RVF). This is a critical question given that the RV is uniquely at risk in patients with congenital right-sided obstructive lesions and in those with systemic RVs. We have developed a murine model of RVH and RVF using pulmonary artery constriction (PAC). miR microarray analysis of RV from PAC vs. control demonstrates altered miR expression with gene targets associated with cardiomyocyte survival and growth during hypertrophy (miR 199a-3p) and reactivation of the fetal gene program during heart failure (miR-208b). The transition from hypertrophy to heart failure is characterized by apoptosis and fibrosis (miRs-34, 21, 1). Most are similar to LVH/LVF. However, there are several key differences between RV and LV: four miRs (34a, 28, 148a, and 93) were upregulated in RVH/RVF that are downregulated or unchanged in LVH/LVF. Furthermore, there is a corresponding downregulation of their putative target genes involving cell survival, proliferation, metabolism, extracellular matrix turnover, and impaired proteosomal function. The current study demonstrates, for the first time, alterations in miRs during the process of RV remodeling and the gene regulatory pathways leading to RVH and RVF. Many of these alterations are similar to those in the afterload-stressed LV. miRs differentially regulated between the RV and LV may contribute to the RVs increased susceptibility to heart failure.
View details for DOI 10.1152/physiolgenomics.00163.2011
View details for Web of Science ID 000304367600003
View details for PubMedID 22454450
Recipient Genotype Is a Predictor of Allograft Cytokine Expression and Outcomes After Pediatric Cardiac Transplantation JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY 2009; 53 (20): 1909-1917
This study sought to investigate the influence of recipient renin-angiotensin-aldosterone system (RAAS) genotype on cardiac function, rejection, and outcomes after heart transplantation.The RAAS influences cardiac function and up-regulates inflammatory/immune pathways. Little is known about the effect of recipient RAAS polymorphisms in pediatric cardiac transplantation.Patients <25 years of age, after cardiac transplantation, were enrolled (2003 to 2008) and genotyped for polymorphisms in genes associated with RAAS upregulation: AGT-G, ACE-D, AGTR1-C, CYP11B2-G, and CMA-A. Presence of at least 1 high-risk allele was defined as a high-risk genotype. Univariable and multivariable associations between genotypes and outcomes were assessed in time-dependent models using survival, logistic, or linear regression models. Biopsy samples were immunostained for interleukin (IL)-6, transforming growth factor (TGF)-beta, and tumor necrosis factor (TNF)-alpha during rejection and quiescence.A total of 145 patients were studied, 103 primary cohort and 42 replication cohort; 81% had rejection, 51% had graft dysfunction, and 13% had vasculopathy, 7% died and 8% underwent re-transplantation. A higher number of homozygous high-risk RAAS genotypes was associated with a higher risk of graft dysfunction (hazard ratio [HR]: 1.5, p = 0.02) and a higher probability of death (HR: 2.5, p = 0.04). The number of heterozygous high-risk RAAS genotypes was associated with frequency of rejection (+0.096 events/year, p < 0.001) and rejection-associated graft dysfunction (+0.37 events/year, p = 0.002). IL-6 and TGF-beta were markedly upregulated during rejection in patients with >/=2 high-risk RAAS genotypes.Recipient RAAS polymorphisms are associated with a higher risk of rejection, graft cytokine expression, graft dysfunction, and a higher mortality after cardiac transplantation. This may have implications for use of RAAS inhibitors in high-risk patients after transplantation.
View details for DOI 10.1016/j.jacc.2009.02.027
View details for Web of Science ID 000266236600012
View details for PubMedID 19442892
Genomic Profiling of Left and Right Ventricular Hypertrophy in Congenital Heart Disease JOURNAL OF CARDIAC FAILURE 2008; 14 (9): 760-767
The right ventricle (RV) has a lower ability than the left ventricle (LV) to adapt to systemic load. The molecular basis of these differences is not known. We compared hypertrophy-signaling pathways between the RV and the LV in patients with congenital heart disease (CHD).Gene expression was measured using DNA microarrays in myocardium from children with CHD with LV or RV obstructive lesions undergoing surgery. The expression of 175 hypertrophy-signaling genes was compared between the LV (n=7) and the RV (n=11). Hierarchic clustering was performed.Seventeen genes (10%) were differentially expressed between the LV and the RV. Expression of genes for angiotensin, adrenergic, G-proteins, cytoskeletal, and contractile components was lower (P < .05) and expression of maladaptive factors (fibroblast growth factors, transforming growth factor-beta, caspases, ubiquitin) was higher in the RV compared with the LV (P < .05). Five of 7 LV samples clustered together. Only 4 of 11 RV samples clustered with the LV. Genes critical to adaptive remodeling correlated with the degree of LV hypertrophy but not RV hypertrophy.The transcription of pathways of adaptive remodeling was lower in the RV compared with the LV. This may explain the lower ability of the RV to adapt to hemodynamic load in CHD.
View details for DOI 10.1016/j.cardfail.2008.06.002
View details for Web of Science ID 000261269800008
View details for PubMedID 18995181
Pyloric Stenosis AAP Textbook on Pediatric Care 2008; Chapter315
RAAS gene polymorphisms influence progression of pediatric hypertrophic cardiomyopathy HUMAN GENETICS 2007; 122 (5): 515-523
Hypertrophic Cardiomyopathy (HCM) is a disease with variable rate of progression. Young age is an independent risk factor for poor outcome in HCM. The influence of renin-angiotensin-aldosterone (RAAS) genotype on the progression of HCM in children is unknown. Children with HCM (n = 65) were enrolled prospectively across two centers (2001-2005). All subjects were genotyped for five RAAS gene polymorphisms previously associated with LV hypertrophy (pro-LVH): AGT M235T, ACE DD, CMA-1903 A/G, AGTR1 1666 A/C and CYP11B2-344 C/T. Linear regression models, based on maximum likelihood estimates, were created to assess the independent effect of RAAS genotype on LV hypertrophy (LVH). Forty-six subjects were homozygous for <2 and 19 were homozygous for > or =2 pro-LVH RAAS polymorphisms. Mean age at presentation was 9.6 +/- 6 years. Forty children had follow-up echocardiograms after a median of 1.5 years. Indexed LV mass (LVMI) and LV mass z-scores were higher at presentation and follow-up in subjects with > or =2 pro-LVH genotypes compared to those with <2 (P < 0.05). Subjects with > or =2 pro-LVH genotypes also demonstrated a greater increase in septal thickness (IVST) and in LV outflow tract (LVOT) obstruction on follow-up (P < 0.05). On multivariate analysis, a higher number of pro-LVH genotypes was associated with a larger effect size (P < 0.05). Pro-LVH RAAS gene polymorphisms are associated with progressive septal hypertrophy and LVOT obstruction in children with HCM. Identification of RAAS modifier genes may help to risk-stratify patients with HCM.
View details for DOI 10.1007/s00439-007-0429-9
View details for Web of Science ID 000251143900011
View details for PubMedID 17851694
Failure of right ventricular adaptation in children with tetralogy of Fallot CIRCULATION 2006; 114: I37-I42
The left ventricle (LV) adapts to chronic hypoxia by expressing protective angiogenic, metabolic, and antioxidant genes to improve O2 delivery and energy production, and to minimize reoxygenation injury. The ability of the right ventricle (RV) to adapt to hypoxia in children with tetralogy of Fallot (TOF) is unknown.Gene expression using real-time polymerase chain reaction was measured in RV myocardium obtained during surgical repair of TOF from 23 patients: 13 cyanotic and 10 acyanotic. Results were compared between the 2 groups and correlated with age at surgery, severity of cyanosis, and early postoperative course. The cyanotic patients were younger at surgery compared with acyanotic (5+/-3 versus 9+/-4 months; P=0.01), had higher hematocrit (43+/-4 versus 38+/-3 grams/dL; P=0.004), and lower O2 saturations (84+/-4% versus 98+/-2%; (P<0.001). Cyanotic patients had a significantly lower expression of vascular endothelial growth factor (VEGF), glycolytic enzymes, and glutathione peroxidase (GPX) (P<0.05), and a higher expression of collagen (P<0.01) compared with acyanotic patients. Gene expression correlated inversely with severity of cyanosis ie, preoperative hematocrit (P<0.01) and positively with preoperative saturation (P<0.05). The relationship between gene expression and cyanosis was independent of age at surgery. Ca2+ handling genes did not correlate with the severity of hypoxia. Lower angiogenic, glycolytic, and antioxidant gene expression correlated with increasing postoperative lactate (P<0.05).The RV fails to up regulate adaptive pathways in response to increasing hypoxia in children with TOF. The implications of an early maladaptive response of the RV on long-term RV function require further investigation.
View details for DOI 10.1161/CIRCULATIONAHA.105.001248
View details for Web of Science ID 000238688200008
View details for PubMedID 16820602
Inlet patch: Heterotopic gastric mucosa - Another contributor to supraesophageal symptoms? JOURNAL OF PEDIATRICS 2005; 147 (3): 379-382
To determine prospectively the incidence of an inlet patch (IP) in children requiring esophagogastroduodenoscopy (EGD) and assess the prevalence of presenting symptoms between children with and without an IP.All patients undergoing EGD in a 2-year period were assessed for the presence of an IP with biopsy confirmation. IP, distal esophagus, and stomach biopsy specimens were blindly reviewed by a pathologist for the presence and degree of inflammation and intestinal metaplasia. Symptoms from children with and without an IP were compared.From 407 EGDs done by a single endoscopist, 24 patients had confirmed IP (incidence of 5.9%). The presence and degree of inflammation were always relatively greater in the columnar mucosa of the IP than in the antral/body gastric mucosa in the same patient (P = .0027) Inflammation was similar in the squamous epithelium around the IP and in the distal esophagus (P=.46). Two patients had intestinal metaplasia of the IP. The patients with IPs had a higher prevalence of respiratory symptoms than the control group (P = .03).Children with IPs may have a higher frequency of respiratory symptoms. Periodic surveillance should be performed in children with intestinal metaplasia of an IP.
View details for DOI 10.1016/j.jpeds.2005.03.002
View details for Web of Science ID 000232412100023
View details for PubMedID 16182679
Restrictive interatrial communication in hypoplastic left heart syndrome after modified Fontan repair ANNALS OF THORACIC SURGERY 2003; 76 (6): 2089-2091
The occurrence of pulmonary venous obstruction after total cavopulmonary connection with intraatrial lateral tunnel is a rare occurrence. We present two cases of hypoplastic left heart syndrome with restrictive interatrial communication presenting late after this type of modified Fontan repair. This occurred even after complete excision of the atrial septum at the time of Stage 1 Norwood in both cases. A novel approach to this problem of resecting the roof of the coronary sinus was utilized to enlarge the interatrial communication.
View details for DOI 10.1016/S0003-4975(03)01173-1
View details for Web of Science ID 000186986500072
View details for PubMedID 14667654