David Gutstein, M.D.

Connexin-43 Expression Regulates the Migration of Hematopoietic Stem Cells and Progenitors towards and From Bone Marrow
Gonzalez-Nieto, D; Chang, KH; Koehler, A; Arnett, J; Dunn, S; Li, L; Ghiaur, G; Sengupta, A; Fishman, G; Gutstein, D; Civitelli, R; Barrio, L; Gunzer, M; Cancelas, J
2009 NOV 20 ;114(22):234-234, Blood
— id: 109972, year: 2009, vol: 114, page: 234, stat: Journal Article,

Connexin-43 Regulates the Cell Cycle Entry of Hematopoietic Stem Cells within the Stem Cell Niche
Gonzalez-Nieto, D; Ghiaur, G; Li, L; Arnett, J; Dunn, S; Fishman, G; Gutstein, D; Civitelli, R; Cancelas, J
2009 NOV 20 ;114(22):602-603, Blood
— id: 109978, year: 2009, vol: 114, page: 602, stat: Journal Article,

Identification of binding partners for the cytoplasmic loop of connexin43: a novel interaction with beta-tubulin
Kang, Eunice Y; Ponzio, Marc; Gupta, Pritha P; Liu, Fangyu; Butensky, Adam; Gutstein, David E
2009 ;15(5-6):397-406, Cell communication & adhesion
Connexin43 (Cx43), a component of gap junctions, has a relatively large carboxy-terminal region with multiple proteomic interactions. Proteomic interactions with its cytoplasmic loop, however, are poorly defined. The goal of this study is to examine proteomic interactions involving the cytoplasmic loop (CL) of Cx43. The authors utilized various techniques, including glutathione-S-transferase (GST) pull-down, immunoblot analysis, two-dimensional (2D) gel electrophoresis, and mass spectrometry, to elucidate binding partners for Cx43-CL. The authors identified novel interactions with Cx43-CL involving alpha- and beta-tubulin, myelin basic protein, and Puralpha. Because tubulin interacts with the C-terminus of Cx43 (Cx43-CT), the authors further investigated the nature of the interaction between beta-tubulin and Cx43-CL. beta-Tubulin binds with the full length of Cx43-CL with approximately one-fifth the affinity of the interaction between Cx43-CT and beta-tubulin. This study demonstrates novel proteomic interactions involving Cx43-CL that may lead to a more complete understanding of trafficking and gating of gap junction channels
— id: 138363, year: 2009, vol: 15, page: 397, stat: Journal Article,

Electrical remodeling contributes to complex tachyarrhythmias in connexin43-deficient mouse hearts
Danik, Stephan B; Rosner, Gregg; Lader, Joshua; Gutstein, David E; Fishman, Glenn I; Morley, Gregory E
2008 Apr;22(4):1204-1212, FASEB journal
Loss of connexin43 (Cx43) gap junction channels in the heart results in a marked increase in the incidence of spontaneous and inducible polymorphic ventricular tachyarrhythmias (PVTs). The mechanisms resulting in this phenotype remain unclear. We hypothesized that uncoupling promotes regional ion channel remodeling, thereby increasing electrical heterogeneity and facilitating the development of PVT. In isolated-perfused control hearts, programmed electrical stimulation elicited infrequent monomorphic ventricular tachyarrhythmias (MVT), and dominant frequencies (DFs) during MVT were similar in the right ventricle (RV) and left ventricle (LV). Moreover, conduction properties, action potential durations (APDs), and repolarizing current densities were similar in RV and LV myocytes. In contrast, PVT was common in Cx43 conditional knockout (OCKO) hearts, and arrhythmias were characterized by significantly higher DFs in the RV compared to the LV. APDs in OCKO myocytes were significantly shorter than those from chamber-matched controls, with RV OCKO myocytes being most affected. APD shortening was associated with higher levels of sustained current in myocytes from both chambers as well as higher levels of the inward rectifier current only in RV myocytes. Thus, alterations in cell-cell coupling lead to regional changes in potassium current expression, which in this case facilitates the development of reentrant arrhythmias. We propose a new mechanistic link between electrical uncoupling and ion channel remodeling. These findings may be relevant not only in cardiac tissue but also to other organ systems where gap junction remodeling is known to occur.-Danik, S. B., Rosner, G., Lader, J., Gutstein, D. E., Fishman, G. I., Morley, G. E. Electrical remodeling contributes to complex tachyarrhythmias in connexin43-deficient mouse hearts
— id: 75197, year: 2008, vol: 22, page: 1204, stat: Journal Article,

A novel proteomic interaction involving the cytoplasmic loop of connexin43 and tubulin
Gupta, PP; Kang, E; Ponzio, M; Butensky, A; Gutstein, DE
2008 MAR 11 ;51(10):A376-A376, Journal of the American College of Cardiology
— id: 78391, year: 2008, vol: 51, page: A376, stat: Journal Article,

Identification of binding partners for the cytoplasmic loop of connexin43: A novel interaction with beta-tubulin
Kang E.Y.; Ponzio M.; Gupta P.; Liu F.; Butensky A.; Gutstein D.E.
2008 ;15(5-6):397-406, Cell communication & adhesion
Connexin43 (Cx43), a component of gap junctions, has a relatively large carboxy-terminal region with multiple proteomic interactions. Proteomic interactions with its cytoplasmic loop, however, are poorly defined. The goal of this study is to examine proteomic interactions involving the cytoplasmic loop (CL) of Cx43. The authors utilized various techniques, including glutathione-S-transferase (GST) pull-down, immunoblot analysis, two-dimensional (2D) gel electrophoresis, and mass spectrometry, to elucidate binding partners for Cx43-CL. The authors identified novel interactions with Cx43-CL involving alpha- and beta-tubulin, myelin basic protein, and Puralpha. Because tubulin interacts with the C-terminus of Cx43 (Cx43-CT), the authors further investigated the nature of the interaction between beta-tubulin and Cx43-CL. beta-Tubulin binds with the full length of Cx43-CL with approximately one-fifth the affinity of the interaction between Cx43-CT and beta-tubulin. This study demonstrates novel proteomic interactions involving Cx43-CL that may lead to a more complete understanding of trafficking and gating of gap junction channels
— id: 102494, year: 2008, vol: 15, page: 397, stat: Journal Article,

Dyssynchronous activation in heterozygous Cx43 germline knockout mice induces steady-state potassium current remodelling and sustained dyssynchrony
Kontogeorgis, A; Kaba, RA; Li, X; Wit, AL; Morley, GE; Peters, NS; Gutstein, DE
2008 JUL ;94(3):A1-A1, Heart (British Cardiac Society)
— id: 86971, year: 2008, vol: 94, page: A1, stat: Journal Article,

Short-term pacing in the mouse alters cardiac expression of connexin43
Kontogeorgis, Andrianos; Kaba, Riyaz A; Kang, Eunice; Feig, Jonathan E; Gupta, Pritha P; Ponzio, Marc; Liu, Fangyu; Rindler, Michael J; Wit, Andrew L; Fisher, Edward A; Peters, Nicholas S; Gutstein, David E
2008 ;8:8-8, BMC Physiology
BACKGROUND: Cardiac insults such as ischemia, infarction, hypertrophy and dilatation are often accompanied by altered abundance and/or localization of the connexin43 gap junction protein, which may predispose towards arrhythmic complications. Models of chronic dyssynchronous cardiac activation have also been shown to result in redistribution of connexin43 in cardiomyocytes. We hypothesized that alterations in connexin43 expression and localization in the mouse heart might be induced by ventricular pacing over a short period of time. RESULTS: The subdiaphragmatic approach was used to pace a series of wild type mice for six hours before the hearts were removed for analysis. Mice were paced at 10-15% above their average anesthetized sinus rate and monitored to ensure 1:1 capture. Short-term pacing resulted in a significant reduction in connexin43 mRNA abundance, a partial redistribution of connexin43 from the sarcolemma to a non-sarcolemmal fraction, and accumulation of ubiquitinated connexin43 without a significant change in overall connexin43 protein levels. These early pacing-induced changes in connexin43 expression were not accompanied by decreased cardiac function, prolonged refractoriness or increased inducibility into sustained arrhythmias. CONCLUSION: Our data suggest that short-term pacing is associated with incipient changes in the expression of the connexin43 gap junction, possibly including decreased production and a slowed rate of degradation. This murine model may facilitate the study of early molecular changes induced by pacing and may ultimately assist in the development of strategies to prevent gap junction remodeling and the associated arrhythmic complications of cardiac disease
— id: 79562, year: 2008, vol: 8, page: 8, stat: Journal Article,

Decreased connexin43 expression in the mouse heart potentiates pacing-induced remodeling of repolarizing currents
Kontogeorgis, Andrianos; Li, Xiaodong; Kang, Eunice Y; Feig, Jonathan E; Ponzio, Marc; Kang, Guoxin; Kaba, Riyaz A; Wit, Andrew L; Fisher, Edward A; Morley, Gregory E; Peters, Nicholas S; Coetzee, William A; Gutstein, David E
2008 Nov;295(5):H1905-H1916, American journal of physiology. Heart & circulatory physiology
Gap junction redistribution and reduced expression, a phenomenon termed gap junction remodeling (GJR), is often seen in diseased hearts and may predispose towards arrhythmias. We have recently shown that short-term pacing in the mouse is associated with changes in connexin43 (Cx43) expression and localization, but not with increased inducibility into sustained arrhythmias. We hypothesized that short-term pacing, if imposed on murine hearts with decreased Cx43 abundance, could serve as a model for evaluating the electrophysiologic effects of GJR. We paced wildtype (normal Cx43 abundance) and heterozygous Cx43 knockout mice (Cx43(+/-), 66% mean reduction in Cx43) for six hours at 10-15% above their average sinus rate. We investigated the electrophysiologic effects of pacing on the whole animal using programmed electrical stimulation, and in isolated ventricular myocytes with patch clamp studies. Cx43(+/-) myocytes had significantly shorter action potential durations (APD) and increased steady state and inward rectifier potassium currents (Iss and IK1, respectively) compared to wildtype littermate cells. In Cx43(+/-) hearts, pacing resulted in significant prolongation of ventricular effective refractory period and action potential duration, and significant diminution of Iss compared to unpaced Cx43(+/-) hearts. However, these changes were not seen in paced wildtype mice. These data suggest that Cx43 abundance plays a critical role in regulating currents involved in myocardial repolarization and their response to pacing. Our study may aid in understanding how dyssynchronous activation of diseased, Cx43-deficient myocardial tissue can lead to electrophysiologic changes which may contribute to the worsened prognosis often associated with pacing in the failing heart. Key words: Connexin43, ventricular myocytes, mouse, gap junction
— id: 116200, year: 2008, vol: 295, page: H1905, stat: Journal Article,

Gap junction communication between uterine stromal cells plays a critical role in pregnancy-associated neovascularization and embryo survival
Laws, Mary J; Taylor, Robert N; Sidell, Neil; DeMayo, Francesco J; Lydon, John P; Gutstein, David E; Bagchi, Milan K; Bagchi, Indrani C
2008 Aug;135(15):2659-2668, Development
In the uterus, the formation of new maternal blood vessels in the stromal compartment at the time of embryonic implantation is critical for the establishment and maintenance of pregnancy. Although uterine angiogenesis is known to be influenced by the steroid hormones estrogen (E) and progesterone (P), the underlying molecular pathways remain poorly understood. Here, we report that the expression of connexin 43 (Cx43), a major gap junction protein, is markedly enhanced in response to E in uterine stromal cells surrounding the implanted embryo during the early phases of pregnancy. Conditional deletion of the Cx43 gene in these stromal cells and the consequent disruption of their gap junctions led to a striking impairment in the development of new blood vessels within the stromal compartment, resulting in the arrest of embryo growth and early pregnancy loss. Further analysis of this phenotypical defect revealed that loss of Cx43 expression resulted in aberrant differentiation of uterine stromal cells and impaired production of several key angiogenic factors, including the vascular endothelial growth factor (Vegf). Ablation of CX43 expression in human endometrial stromal cells in vitro led to similar findings. Collectively, these results uncovered a unique link between steroid hormone-regulated cell-cell communication within the pregnant uterus and the development of an elaborate vascular network that supports embryonic growth. Our study presents the first evidence that Cx43-type gap junctions play a critical and conserved role in modulating stromal differentiation, and regulate the consequent production of crucial paracrine signals that control uterine neovascularization during implantation
— id: 96574, year: 2008, vol: 135, page: 2659, stat: Journal Article,

Connexin40 imparts conduction heterogeneity to atrial tissue
Leaf, David E; Feig, Jonathan E; Vasquez, Carolina; Riva, Pamela L; Yu, Cindy; Lader, Joshua M; Kontogeorgis, Andrianos; Baron, Elvera L; Peters, Nicholas S; Fisher, Edward A; Gutstein, David E; Morley, Gregory E
2008 Oct 24;103(9):1001-1008, Circulation research
Impulse propagation in cardiac tissue is a complex process in which intercellular coupling through gap junction channels is a critical component. Connexin40 (Cx40) is an abundant gap junction protein that is expressed in atrial myocytes. Alterations in the expression of Cx40 have been implicated in atrial arrhythmogenesis. The purpose of the current study was to assess the role of Cx40 in atrial impulse propagation. High-resolution optical mapping was used to study conduction in the right and left atrial appendages of isolated Langendorff-perfused murine hearts. Wild-type (Cx40(+/+)), heterozygous (Cx40(+/-)), and knockout (Cx40(-/-)) mice, both adult and embryonic, were studied to assess the effects of reduced Cx40 expression on sinus node function and conduction velocity at different pacing cycle lengths (100 and 60 ms). In both adult and late-stage embryonic Cx40(+/+) mice, heterogeneity in CV was found between the right and left atrial appendages. Either partial (Cx40(+/-)) or complete (Cx40(-/-)) deletion of Cx40 was associated with the loss of conduction heterogeneity in both adult and embryonic mice. Additionally, sinus node impulse initiation was found to be ectopic in Cx40(-/-) mice at 15.5 days postcoitus, whereas Cx40(+/+) mice showed normal activation occurring near the crista terminalis. Our findings suggest that Cx40 plays an essential role in establishing interatrial conduction velocity heterogeneity in the murine model. Additionally, we describe for the first time a developmental requirement for Cx40 in normal sinus node impulse initiation at 15.5 days postcoitus
— id: 93330, year: 2008, vol: 103, page: 1001, stat: Journal Article,

Targeted deletion of kcne2 impairs ventricular repolarization via disruption of I(K,slow1) and I(to,f)
Roepke, Torsten K; Kontogeorgis, Andrianos; Ovanez, Christopher; Xu, Xianghua; Young, Jeffrey B; Purtell, Kerry; Goldstein, Peter A; Christini, David J; Peters, Nicholas S; Akar, Fadi G; Gutstein, David E; Lerner, Daniel J; Abbott, Geoffrey W
2008 Oct;22(10):3648-3660, FASEB journal
Mutations in human KCNE2, which encodes the MiRP1 potassium channel ancillary subunit, associate with long QT syndrome (LQTS), a defect in ventricular repolarization. The precise cardiac role of MiRP1 remains controversial, in part, because it has marked functional promiscuity in vitro. Here, we disrupted the murine kcne2 gene to define the role of MiRP1 in murine ventricles. kcne2 disruption prolonged ventricular action potential duration (APD), suggestive of reduced repolarization capacity. Accordingly, kcne2 (-/-) ventricles exhibited a 50% reduction in I(K,slow1), generated by Kv1.5--a previously unknown partner for MiRP1. I(to,f), generated by Kv4 alpha subunits, was also diminished, by approximately 25%. Ventricular MiRP1 protein coimmunoprecipitated with native Kv1.5 and Kv4.2 but not Kv1.4 or Kv4.3. Unexpectedly, kcne2 (-/-) ventricular membrane fractions exhibited 50% less mature Kv1.5 protein than wild type, and disruption of Kv1.5 trafficking to the intercalated discs. Consistent with the reduction in ventricular K(+) currents and prolonged ventricular APD, kcne2 deletion lengthened the QT(c) under sevoflurane anesthesia. Thus, targeted disruption of kcne2 has revealed a novel cardiac partner for MiRP1, a novel role for MiRPs in alpha subunit targeting in vivo, and a role for MiRP1 in murine ventricular repolarization with parallels to that proposed for the human heart
— id: 96573, year: 2008, vol: 22, page: 3648, stat: Journal Article,

Transgenic expression of a dominant negative K(ATP) channel subunit in the mouse endothelium: effects on coronary flow and endothelin-1 secretion
Malester, Brian; Tong, Xiaoyong; Ghiu, Ioana; Kontogeorgis, Andrianos; Gutstein, David E; Xu, Jie; Hendricks-Munoz, Karen D; Coetzee, William A
2007 Jul;21(9):2162-2172, FASEB journal
K(ATP) channels are involved in regulating coronary function, but the contribution of endothelial K(ATP) channels remains largely uncharacterized. We generated a transgenic mouse model to specifically target endothelial K(ATP) channels by expressing a dominant negative Kir6.1 subunit only in the endothelium. These animals had no obvious overt phenotype and no early mortality. Histologically, the coronary endothelium in these animals was preserved. There was no evidence of increased susceptibility to ergonovine-induced coronary vasospasm. However, isolated hearts from these animals had a substantially elevated basal coronary perfusion pressure. The K(ATP) channel openers, adenosine and levcromakalim, decreased the perfusion pressure whereas the K(ATP) channel blocker glibenclamide failed to produce a vasoconstrictive response. The inducible endothelial nitric oxide pathway was intact, as evidenced by vasodilation caused by bradykinin. In contrast, basal endothelin-1 release was significantly elevated in the coronary effluent from these hearts. Treatment of mice with bosentan (endothelin-1 receptor antagonist) normalized the coronary perfusion pressure, demonstrating that the elevated endothelin-1 release was sufficient to account for the increased coronary perfusion pressure. Pharmacological blockade of K(ATP) channels led to elevated endothelin-1 levels in the coronary effluent of isolated mouse and rat hearts as well as enhanced endothelin-1 secretion from isolated human coronary endothelial cells. These data are consistent with a role for endothelial K(ATP) channels to control the coronary blood flow by modulating the release of the vasoconstrictor, endothelin-1
— id: 73407, year: 2007, vol: 21, page: 2162, stat: Journal Article,

Proliferation of adult sertoli cells following conditional knockout of the Gap junctional protein GJA1 (connexin 43) in mice
Sridharan, Santhi; Simon, Liz; Meling, Daryl D; Cyr, Daniel G; Gutstein, David E; Fishman, Glenn I; Guillou, Florian; Cooke, Paul S
2007 May;76(5):804-812, Biology of reproduction
GJA1 (also known and referred to here as connexin 43 and abbreviated CX43) is the predominant testicular gap junction protein, and CX43 may regulate Sertoli cell maturation and spermatogenesis. We hypothesized that lack of CX43 would inhibit Sertoli cell differentiation and extend proliferation. To test this, a Sertoli cell-specific Cx43 knockout (SC-Cx43 KO) mouse was generated using Cre-lox technology. Immunohistochemistry indicated that CX43 was not expressed in the Sertoli cells of SC-Cx43 KO mice, but was normal in organs such as the heart. Testicular weight was reduced by 41% and 76% in SC-Cx43 KO mice at 20 and 60 days, respectively, vs. wild-type (wt) mice. Seminiferous tubules of SC-Cx43 KO mice contained only Sertoli cells and actively proliferating early spermatogonia. Sertoli cells normally cease proliferation at 2 wk of age in mice and become terminally differentiated. However, proliferating Sertoli cells were present in SC-Cx43 KO but not wt mice at 20 and 60 days of age. Thyroid hormone receptor alpha (THRA) is high in proliferating Sertoli cells, then declines sharply in adulthood. Thra mRNA expression was increased in 20-day SC-Cx43 KO vs. wt mice, and it showed a trend toward an increase in 60-day mice, indicating that loss of CX43 in Sertoli cells inhibited their maturation. In conclusion, we have generated mice lacking CX43 in Sertoli cells but not other tissues. Our data indicate that CX43 in Sertoli cells is essential for spermatogenesis but not spermatogonial maintenance/proliferation. SC-Cx43 KO mice showed continued Sertoli cell proliferation and delayed maturation in adulthood, indicating that CX43 plays key roles in Sertoli cell development
— id: 96066, year: 2007, vol: 76, page: 804, stat: Journal Article,

Long form of latent TGF-{beta} binding protein 1 (Ltbp1L) is essential for cardiac outflow tract septation and remodeling
Todorovic, Vesna; Frendewey, David; Gutstein, David E; Chen, Yan; Freyer, Laina; Finnegan, Erin; Liu, Fangyu; Murphy, Andrew; Valenzuela, David; Yancopoulos, George; Rifkin, Daniel B
2007 Oct;134(20):3723-3732, Development
Latent TGF-beta binding protein 1 (LTBP1) is a member of the LTBP/fibrillin family of extracellular proteins. Due to the usage of different promoters, LTBP1 exists in two major forms, long (L) and short (S), each expressed in a temporally and spatially unique fashion. Both LTBP1 molecules covalently interact with latent TGF-beta and regulate its function, presumably via interaction with the extracellular matrix (ECM). To explore the in vivo role of Ltbp1 in mouse development, at the time when only the L isoform is expressed, we mutated the Ltbp1L locus by gene targeting. Ltbp1L-null animals die shortly after birth from defects in heart development, consisting of the improper septation of the cardiac outflow tract (OFT) and remodeling of the associated vessels. These cardiac anomalies present as persistent truncus arteriosus (PTA) and interrupted aortic arch (IAA), which are associated with the faulty function of cardiac neural crest cells (CNCCs). The lack of Ltbp1L in the ECM of the septating OFT and associated vessels results in altered gene expression and function of CNCCs and decreased Tgf-beta activity in the OFT. This phenotype reveals a crucial role for Ltbp1L and matrix as extracellular regulators of Tgf-beta activity in heart organogenesis
— id: 74213, year: 2007, vol: 134, page: 3723, stat: Journal Article,

Contrast-enhanced MRI of right ventricular abnormalities in Cx43 mutant mouse embryos
Wadghiri, Youssef Zaim; Schneider, Amanda E; Gray, Emily N; Aristizabal, Orlando; Berrios, Cesar; Turnbull, Daniel H; Gutstein, David E
2007 May;20(3):366-374, NMR in biomedicine
Imaging of the mammalian cardiac right ventricle (RV) is particularly challenging, especially when a two-dimensional method such as conventional histology is used to evaluate the morphology of this asymmetric, crescent-shaped chamber. MRI may improve the characterization of mutants with RV phenotypes by allowing analysis of the samples in any plane and by facilitating three-dimensional image reconstruction. MRI was used to examine the conditional knockout Cx43-PCKO mouse line known to have RV malformations. To help delineate the cardiovascular system and facilitate identification of the right ventricular outflow tract (RVOT), embryonic day (E) 17.5 embryos were perfusion fixed through the umbilical vein followed by a gadolinium-based contrast agent mixed in 7% gelatin. Micro-MRI experiments were performed at 7 T and followed by paraffin embedding of specimens, histological sectioning and hematoxylin and eosin (H&E) staining. Imaging of up to four embryos simultaneously allowed for higher throughput than traditional individual imaging techniques, while intravascular contrast afforded excellent signal-to-noise characteristics. All control embryos (n = 4) and heterozygous Cx43 knockout embryos (n = 4) had normal-appearing right ventricular outflow tract contours by MRI. Obvious abnormalities in the RVOT, including abnormal bulging and infiltration of contrast into the wall of the RV, were seen in three out of four Cx43-PCKO mutants with MRI. Furthermore, three-dimensional reconstruction of MR images with orthogonal projections as well as maximum-intensity projection allowed for visualization of the relationship of infundibular bulging segments to the pulmonary trunk in Cx43-PCKO mutant hearts. The addition of MRI to standard histology in the characterization of RV malformations in mutant mouse embryos aids in the assessment and understanding of morphologic abnormalities. Flexibility in the viewing of MR images, which can be retrospectively sectioned in any desired orientation, is particularly useful in the investigation of the RV, an asymmetric chamber that is difficult to analyze with two-dimensional techniques.
— id: 72869, year: 2007, vol: 20, page: 366, stat: Journal Article,

Dyskinesis in Chagasic myocardium: centerline analysis of wall motion using cardiac-gated magnetic resonance images of mice
Durand, Jorge L; Tang, Baiyu; Gutstein, David E; Petkova, Stefka; Teixeira, Mauro M; Tanowitz, Herbert B; Jelicks, Linda A
2006 Oct;24(8):1051-1057, Magnetic resonance imaging
We report on the use of centerline analysis of cardiac-gated magnetic resonance images to measure wall motion abnormalities in mice infected with Trypanosoma cruzi. To our knowledge, this is the first report of segmental wall motion abnormalities in an animal model of Chagas' disease. Chagas' disease patients with severe cardiac involvement exhibit mild hypokinesis in an extensive region of the left ventricle and dyskinesis in the apical region. We observed dyskinetic segments in a similar region of the hearts of infected wild-type mice. Dyskinesis was not observed in infected mice lacking macrophage inflammatory protein-1alpha, a chemokine that may play an important role in the cardiac remodeling that is normally observed in mouse models of Chagas' disease and in human patients. This study aimed to demonstrate the utility of cardiac-gated magnetic resonance imaging and centerline analysis as a straightforward method for monitoring regional left ventricular wall motion in transgenic and/or diseased mice
— id: 96575, year: 2006, vol: 24, page: 1051, stat: Journal Article,

Short-term ventricular pacing induces gap junctional remodelling in the murine heart
Kaba, R; Kontogeorgis, A; Sereysky, J; Lewitton, S; Wit, A; Peters, N; Gutstein, D
2006 MAY ;92(21):A99-A99, Heart (British Cardiac Society)
— id: 64400, year: 2006, vol: 92, page: A99, stat: Journal Article,

Distinct cardiac malformations caused by absence of connexin 43 in the neural crest and in the non-crest neural tube
Liu, Shasha; Liu, Fangyu; Schneider, Amanda E; St Amand, Tara; Epstein, Jonathan A; Gutstein, David E
2006 May;133(10):2063-2073, Development
Connexin 43 (Cx43) is expressed in the embryonic heart, cardiac neural crest (CNC) and neural tube, and germline knockout (KO) of Cx43 results in aberrant cardiac outflow tract (OFT) formation and abnormal coronary deployment. Prior studies suggest a vital role for CNC expression of Cx43 in heart development. Surprisingly, we found that conditional knockout (CKO) of Cx43 in the dorsal neural tube and CNC mediated by Wnt1-Cre failed to recapitulate the Cx43-null OFT phenotype, although coronary vasculature was abnormal in this mutant line. A broader CKO mediated by P3pro (Pax3)-Cre, involving both ventral and dorsal aspects of the thoracic neural tube and CNC, resulted in infundibular bulging and coronary anomalies similar to those seen in germline Cx43-null hearts. P3pro-Cre-mediated loss of Cx43 in the neural tube was characterized by a late phase of cellular delamination from the dorsal and lateral neural tube, a markedly increased abundance of neuroepithelium-derived cells outside of the neural tube and an excess of such cells infiltrating the heart and infundibulum. Thus, expression of Cx43 in the CNC is crucial for normal coronary deployment, but Cx43 is not required in the CNC for normal OFT morphogenesis. Rather, this study suggests a novel function for Cx43 in which Cx43 acts through non-crest neuroepithelial cells to suppress cellular delamination from the neural tube and thereby preserve normal OFT development
— id: 64787, year: 2006, vol: 133, page: 2063, stat: Journal Article,

Cardiac outflow tract defects in mice lacking LTBP-1L
Todorovic, V; Freyer, L; Gutstein, D; Frendewey, D; Rifkin, D
2006 NOV ;25(2):S26-S26, Matrix biology
— id: 70620, year: 2006, vol: 25, page: S26, stat: Journal Article,

Consequences of Cardiac Myocyte-Specific Ablation of KATP channels in Transgenic Mice expressing Dominant Negative Kir6 Subunits
Tong, XiaoYong; Porter, Lisa M; Liu, GongXin; Dhar-Chowdhury, Piyali; Srivastava, Shekhar; Pountney, David J; Yoshida, Hidetada; Artman, Michael; Fishman, Glenn I; Yu, Cindy; Iyer, Ramesh; Morley, Gregory E; Gutstein, David E; Coetzee, William A
2006 Aug;291(2):H543-H551, American journal of physiology. Heart & circulatory physiology
Cardiac KATP channels are formed by Kir6.2 and SUR2A subunits. We produced transgenic mice which express dominant negative Kir6.x pore-forming subunits (Kir6.1-AAA or Kir6.2-AAA) in cardiac myocytes by driving their expression with the alpha-myosin heavy chain promoter. Weight gain and development after birth of these mice were similar to wild-type mice, but an increased mortality was noted after the age of 4-5 months. Transgenic mice lacked cardiac KATP channel activity as assessed with patch clamp techniques. Consistent with a decreased current density observed at positive voltages, the action potential duration was increased in these mice. Some myocytes developed early afterdepolarizations following isoproterenol treatment. Hemodynamic measurements revealed no significant effects on ventricular function (apart from a slightly elevated heart rate) whereas in-vivo electrophysiological recordings revealed a prolonged ventricular effective refractory period in transgenic mice. The transgenic mice tolerated stress less well as evident from treadmill stress tests. The pro-arrhythmogenic features and lack of adaptation to a stress response in transgenic mice suggests that these features are intrinsic to the myocardium and that KATP channels in the myocardium have an important role in protecting the heart from lethal arrhythmias and adaptation to stress situations
— id: 63616, year: 2006, vol: 291, page: H543, stat: Journal Article,

MR imaging of caveolin gene-specific alterations in right ventricular wall thickness
De Souza, Andrea Pereira; Cohen, Alex W; Park, David S; Woodman, Scott E; Tang, Baiyu; Gutstein, David E; Factor, Stephen M; Tanowitz, Herbert B; Lisanti, Michael P; Jelicks, Linda A
2005 Jan;23(1):61-68, Magnetic resonance imaging
Caveolin-1 and caveolin-3 are expressed in the mammalian heart. Mice deficient in caveolin 1 or 3 exhibit cardiac abnormalities including left ventricular hypertrophy and reduced fractional shortening. Cardiac imaging technologies such as transthoracic echocardiography and cardiac-gated magnetic resonance imaging (MRI) are effective tools for the study of left ventricular morphology and function in mice; however, there has not been widespread use of these technologies in studies of right ventricular morphology. In particular, right ventricular wall thickness has been difficult to assess using cardiac imaging technologies. We report here the use of centerline analysis of cardiac-gated MR images to more accurately determine right ventricular wall thickness in the mouse heart. Right ventricular wall thickness was evaluated in Cav-1 null, Cav-3 null and Cav-1/3 null mice, as well as wild-type control mice. Using this technique, we find that caveolin null mice exhibit significant thickening of the right ventricular wall as compared with age-matched wild-type controls. Interestingly, right ventricular wall thickening is greatest in the Cav-1/3 null mice. Furthermore, significant right ventricular wall thickening is also seen in the Cav-1 null mice. Histological analyses revealed right ventricular hypertrophy consistent with the imaging results. These studies demonstrate the utility of MRI in determining right ventricular wall thickness and underscore the severity of the right ventricular hypertrophy in caveolin null mice
— id: 60891, year: 2005, vol: 23, page: 61, stat: Journal Article,

Focal Gap Junction Uncoupling and Spontaneous Ventricular Ectopy
Gutstein, David E; Danik, Stephan B; Lewitton, Steve; France, David; Liu, Fangyu; Chen, Franklin L; Zhang, Jie; Ghodsi, Newsha; Morley, Gregory E; Fishman, Glenn I
2005 Sep;289(3):H1091-H1098, American journal of physiology. Heart & circulatory physiology
Genetic studies in the mouse have demonstrated that conditional cardiac-resticted loss of connexin43 (Cx43), the major ventricular gap junction protein, is highly arrhythmogenic. However, whether more focal gap junction remodeling, as is commonly seen in acquired cardiomyopathies, influences the propensity for arrhythmogenesis is not known. We examined electrophysiological properties and the frequency of spontaneous and inducible arrhythmias in genetically engineered chimeric mice derived from injection of Cx43-deficient embryonic stem cells into wildtype recipient blastocysts. Chimeric mice had numerous well-circumscribed microscopic Cx43-negative foci in their hearts, comprising ~ 15% of the total surface area as determined by immunohistochemical analysis. Systolic function in the chimeric mice was significantly depressed as measured echocardiographically (19.0% decline in fractional shortening compared with controls, p < 0.05) and by invasive hemodynamics (17.6% reduction in dP/dT, p < 0.01). Chimeras had significantly more spontaneous arrhythmic events than controls (p < 0.01), including frequent runs of non-sustained ventricular tachycardia in some of the chimeric mice. However, in contrast to mice with conditional cardiac-resticted loss of Cx43 in the heart, no sustained ventricular tachyarrhythmias were observed. We conclude that focal areas of uncoupling in the myocardium increase the likelihood of arrhythmic triggers, but more widespread uncoupling is required to support sustained arrhythmias
— id: 56033, year: 2005, vol: 289, page: H1091, stat: Journal Article,

Bone marrow connexin-43 expression is critical for hematopoietic regeneration after chemotherapy
Lee, AW; Presley, CA; Kastl, BD; Igbinosa, II; Yamada, Y; Fishman, GI; Gutstein, DE; Cancelas, JA
2005 NOV 16 ;106(11):141A-141A, Blood
— id: 61461, year: 2005, vol: 106, page: 141A, stat: Journal Article,

Reduced intercellular coupling leads to paradoxical propagation across the Purkinje-ventricular junction and aberrant myocardial activation
Morley, Gregory E; Danik, Stephan B; Bernstein, Scott; Sun, Yanjie; Rosner, Gregg; Gutstein, David E; Fishman, Glenn I
2005 Mar 15;102(11):4126-4129, Proceedings of the National Academy of Sciences of the United States of America
Ventricular tachycardia is a common heart rhythm disorder and a frequent cause of sudden cardiac death. Aberrant cell-cell coupling through gap junction channels, a process termed gap junction remodeling, is observed in many of the major forms of human heart disease and is associated with increased arrhythmic risk in both humans and in animal models. Genetically engineered mice with cardiac-restricted knockout of Connexin43, the major cardiac gap junctional protein, uniformly develop sudden cardiac death, although a detailed electrophysiological understanding of their profound arrhythmic propensity is unclear. Using voltage-sensitive dyes and high resolution optical mapping techniques, we found that uncoupling of the ventricular myocardium results in ectopic sites of ventricular activation. Our data indicate that this behavior reflects alterations in source-sink relationships and paradoxical conduction across normally quiescent Purkinje-ventricular muscle junctions. The aberrant activation profiles are associated with wavefront collisions, which in the setting of slow conduction may account for the highly arrhythmogenic behavior of Connexin43-deficient hearts. Thus, the extent of gap junction remodeling in diseased myocardium is a critical determinant of cardiac excitation patterns and arrhythmia susceptibility
— id: 52629, year: 2005, vol: 102, page: 4126, stat: Journal Article,

Bone marrow connexin-43 expression is critical for hematopoietic regeneration after chemotherapy
Presley, Cynthia A; Lee, Andrew W; Kastl, Bryan; Igbinosa, Irogue; Yamada, Yoshiyuki; Fishman, Glenn I; Gutstein, David E; Cancelas, Jose A
2005 Jul-Dec;12(5-6):307-317, Cell communication & adhesion
Contact between bone marrow (BM) hematopoietic stem cells (HSC) and osteoblast/stromal (OS) cells has been shown to be crucial in the regulation of hematopoiesis. However, very little is known about the regulatory mechanisms of direct cell-to-cell communication in the hematopoietic microenvironment. Gap junction channels (connexons) are formed by polypeptides (connexins) arranged in hexamers and represent the best described intercellular communication system. Connexin-43 (Cx43) is expressed by BM OS cells and has been associated with the cadherin/beta -catenin signaling pathway, recently reported as relevant in the OS/HSC interaction at the stem cell niche. Here, we employed an inducible gene-targeted murine approach to study the role of Cx43 in HSC proliferation and differentiation in vivo. Mx-Cre/Cx43+/+ and Mx-Cre/Cx43flox/flox littermates have been analyzed after gene deletion induced in vivo by the interferon-inducer poly (I)-poly (C), generating control (Cx43+) and Cx43-deficient (Cx43-/-) mice. After one week, Cx43+ and Cx43-/- mice were treated with 5-fluorouracil (5-FU). Cx43 expression in Cx43-/- BM was markedly reduced (> 90%) as analyzed on day +14 post-5-FU treatment. Cx43 deficiency did not induce a significant change in peripheral blood counts before 5-FU treatment, but the hematopoiesis recovery after 5-FU treatment was severely impaired as demonstrated by absence of recovery of peripheral blood counts, including profound neutropenia, anemia with reticulocytopenia, thrombocytopenia and a 5- to 8-fold decrease of cellularity and hematopoietic progenitor content (granulomacrophagic colony-forming-units (CFU-GM-), erythroid burst forming units (BFU-E) and mixed colony forming units (CFU-mix-) in BM and spleen on day +14 post-5-FU treatment. However, the femoral content of Lin-/c-kit+/Sca1+ cells in Cx43-/- BM was maintained when compared to Cx43+ BM. Short-term competitive repopulation ability of Cx43-/- BM cells was diminished as compared to Cx43+ mice, specifically for myeloid and B lymphoid cells, but showed spared long-term competitive repopulation ability with roughly normal hematopoietic differentiation. These data suggest that hematopoietic regeneration after cycle-specific chemotherapy is blocked in Cx43-deficient mice at the long-term HSC repopulating level. Cx43 expression within the BM appears to be crucial in the development of an efficient response to hematopoietic stress
— id: 63617, year: 2005, vol: 12, page: 307, stat: Journal Article,

Modulation of cardiac gap junction expression and arrhythmic susceptibility
Danik, Stephan B; Liu, Fangyu; Zhang, Jie; Suk, H Jacqueline; Morley, Gregory E; Fishman, Glenn I; Gutstein, David E
2004 Nov 12;95(10):1035-1041, Circulation research
Connexin43 (Cx43), the predominant ventricular gap junction protein, is critical for maintaining normal cardiac electrical conduction, and its absence in the mouse heart results in sudden arrhythmic death. The mechanisms linking reduced Cx43 abundance in the heart and inducibility of malignant ventricular arrhythmias have yet to be established. In this report, we investigate arrhythmic susceptibility in a murine model genetically engineered to express progressively decreasing levels of Cx43. Progressively older cardiac-restricted Cx43 conditional knockout (CKO) mice were selectively bred to produce a heart-specific Cx43-deficient subline ('O-CKO' mice) in which the loss of Cx43 in the heart occurs more gradually. O-CKO mice lived significantly longer than the initial series of CKO mice but still died suddenly and prematurely. At 25 days of age, cardiac Cx43 protein levels decreased to 59% of control values (P<0.01), but conduction velocity was not significantly decreased and no O-CKO mice were inducible into sustained ventricular tachyarrhythmias. By 45 days of age, cardiac Cx43 abundance had decreased in a heterogeneous fashion to 18% of control levels, conduction velocity had slowed to half of that observed in control hearts, and 80% of O-CKO mice were inducible into lethal tachyarrhythmias. Enhanced susceptibility to induced arrhythmias was not associated with altered invasive hemodynamic measurements or changes in ventricular effective refractory period. Thus, moderately severe reductions in Cx43 abundance are associated with slowing of impulse propagation and a dramatic increase in the susceptibility to inducible ventricular arrhythmias
— id: 48218, year: 2004, vol: 95, page: 1035, stat: Journal Article,

Subdiaphragmatic murine electrophysiological studies: sequential determination of ventricular refractoriness and arrhythmia induction
Gutstein, David E; Danik, Stephan B; Sereysky, Jedd B; Morley, Gregory E; Fishman, Glenn I
2003 Sep;285(3):H1091-H1096, American journal of physiology. Heart & circulatory physiology
Programmed electrical stimulation (PES) is a crucial aspect of the evaluation of the risk of arrhythmias in cardiac patients and provides a powerful tool for understanding the mechanisms of arrhythmia in experimental models. Whereas PES in the mouse is well characterized, the procedures allowing for follow-up studies in the same animal have not been developed. In this report, we describe a novel subdiaphragmatic approach that allows for repeat electrophysiological studies in the mouse. Under inhaled anesthesia, PES was performed in 36 wild-type mice via a stimulating electrode introduced through an epigastric incision and placed directly into the diaphragmatic surface of the heart. The procedure was repeated 7 days later. Ventricular effective refractory periods (VERP) did not change significantly between the initial and follow-up trials. Chronic treatment with amiodarone, however, was associated with a 70% prolongation in VERP from initial to follow-up studies (P < or = 0.001). In addition, PES of a genetically modified strain with sudden cardiac death, the connexin43 conditional knockout mouse consistently induced lethal polymorphic ventricular tachycardia. Thus sequential PES in mice is feasible with the use of a subdiaphragmatic approach, yields reproducible VERP values, and can be used to follow pharmacologically induced changes in VERP and identify mice at risk of lethal ventricular arrhythmias
— id: 39225, year: 2003, vol: 285, page: H1091, stat: Journal Article,

The organization of adherens junctions and desmosomes at the cardiac intercalated disc is independent of gap junctions
Gutstein, David E; Liu, Fang-Yu; Meyers, Marian B; Choo, Andrew; Fishman, Glenn I
2003 Mar 1;116(Pt 5):875-885, Journal of cell science
Adherens junctions and desmosomes are responsible for mechanically coupling myocytes in the heart and are found closely apposed to gap junction plaques at the intercalated discs of cardiomyocytes. It is not known whether loss of cardiac gap junctions, such as described in cardiac disease states, may influence the expression patterns of other intercalated disc-associated proteins. We investigated whether the major cardiac gap junction protein connexin43 (Cx43) may be responsible for regulating adherens junctions, desmosomes and their associated catenins, in terms of abundance and localization at the intercalated discs of cardiomyocytes. In order to study the effect of loss of cardiac gap junctions on the intercalated disc-associated proteins, we used a combination of immunoblotting, immunofluorescence with confocal microscopy and electron microscopy to evaluate heart tissue from mice with cardiac-specific conditional knockout of Cx43. We found that the cardiac adherens junctions, desmosomes and their associated catenins, as well as vinculin and ZO-1, maintain their normal abundance, structural appearance and localization in the absence of Cx43. We conclude from these data that Cx43 is not required for the organization of the cell adhesion junctions and their associated catenins at the intercalated disc in the adult cardiac myocyte
— id: 39315, year: 2003, vol: 116, page: 875, stat: Journal Article,

Cell coupling between ventricular myocyte pairs from connexin43-deficient murine hearts
Yao, Jian-An; Gutstein, David E; Liu, Fangyu; Fishman, Glenn I; Wit, Andrew L
2003 Nov 17;93(8):736-743, Circulation research
Mice with cardiac-restricted inactivation of the connexin43 gene (CKO mice) have moderate slowing of ventricular conduction and lethal arrhythmias. Mechanisms through which propagation is maintained in the absence of Cx43 are unknown. We evaluated gap junctional conductance in CKO ventricular pairs using dual patch clamp methods. Junctional coupling was reduced to 4+/-2 nS (side-to-side) and 11+/-2 nS (end-to-end), including 21% of cell-pairs with no detectable coupling, compared with 588+/-104 nS (side-to-side) and 558+/-92 nS (end-to-end) in control cell-pairs. Voltage dependence of control gap junctions was characteristic of Cx43. CKO conductance showed increased voltage dependence, suggesting low-level expression of other connexin isoforms. From theoretical models, this degree of CKO coupling is not expected to support levels of conduction persisting in vivo, suggesting the possibility that there are additional mechanisms for maintained propagation when gap junctional conductance is severely reduced
— id: 45733, year: 2003, vol: 93, page: 736, stat: Journal Article,

Progressive loss of connexin43 in the heart yields a phenotypic shift from ventricular dysfunction to fatal arrhythmias
Gutstein, DE; Liu, FY; Zhang, J; Chen, FL; Ghodsi, N; Kini, AS; Fishman, GI
2002 NOV 5 ;106(19):152-153, Circulation
— id: 37201, year: 2002, vol: 106, page: 152, stat: Journal Article,

The cardiac gap junction: a potential therapeutic target in the treatment of heart disease
Liu, Fangyu; Gutstein, David E
2002 Nov;69(6):421-424, Mount Sinai journal of medicine
Cardiac gap junctions have been implicated in maintaining cardiac conduction and function. In cardiac disease, expression of connexin 43, the most abundant ventricular gap junction protein, is markedly abnormal, a process termed gap junction remodeling. To date, however, the gap junction has not been directly targeted therapeutically in cardiac disease states. Therefore, we have developed novel and complementary experimental models to investigate whether loss of connexin 43 expression in the heart can be directly linked to the arrhythmic and functional complications of heart disease. In this article, we discuss how data from connexin 43 conditional and chimeric knock-out mice support the hypothesis that gap junction remodeling is a key molecular feature underlying the high incidence of sudden arrhythmic death and exacerbating the ventricular dysfunction associated with acquired heart disease
— id: 60892, year: 2002, vol: 69, page: 421, stat: Journal Article,

Exercise training normalizes altered calcium-handling proteins during development of heart failure
Lu, Lu; Mei, Dan Feng; Gu, An-Guo; Wang, Su; Lentzner, Benjamin; Gutstein, David E; Zwas, Donna; Homma, Shunichi; Yi, Geng-Hua; Wang, Jie
2002 Apr;92(4):1524-1530, Journal of applied physiology (Bethesda)
The cardiac sarcoplasmic reticulum calcium-ATPase (SERCA2a), Na(+)/Ca(2+) exchanger (NCX1), and ryanodine receptor (RyR2) are proteins involved in the regulation of myocyte calcium. We tested whether exercise training (ET) alters those proteins during development of chronic heart failure (CHF). Ten dogs were chronically instrumented to permit hemodynamic measurements. Five dogs underwent 4 wk of cardiac pacing (210 beats/min for 3 wk and 240 beats/min for the 4th wk), whereas five dogs underwent the same pacing regimen plus daily ET (5.1 +/- 0.3 km/h, 2 h/day). Paced animals developed CHF characterized by hemodynamic abnormalities and reduced ejection fraction. ET preserved resting hemodynamics and ejection fraction. Left ventricular samples were obtained from all dogs and another five normal dogs for mRNA (Northern analysis, band intensities normalized to glyceraldehyde-3-phosphate dehydrogenase) and protein level (Western analysis, band intensities normalized to tubulin) measurements. In failing hearts, SERCA2a was decreased by 33% (P < 0.05) and 65% (P < 0.05) in mRNA and protein level, respectively, compared with normal hearts; there was only an 8.6% reduction in mRNA and a 32% reduction in protein in exercised animals (P < 0.05 from CHF). mRNA expression of NCX1 increased by 44% in paced-only dogs compared with normal (P < 0.05) but only by 22% in trained dogs (P < 0.05 vs. CHF); protein level of NCX1 was elevated in paced-only dogs (71%, P < 0.05) but partially normalized by ET (33%, P < 0.05 from CHF). RyR2 was not altered in any of the dogs. In conclusion, long-term ET may ameliorate cardiac deterioration during development of CHF, in part via normalization of myocardial calcium-handling proteins
— id: 27762, year: 2002, vol: 92, page: 1524, stat: Journal Article,

Conditional gene targeting of connexin43: exploring the consequences of gap junction remodeling in the heart
Gutstein DE; Morley GE; Fishman GI
2001 ;8(4-6):345-348, Cell adhesion & communications
Abnormalities in cardiac gap junction expression have been postulated to contribute to arrhythmias and ventricular dysfunction. We investigated the role of cardiac gap junctions by generating a heart-specific conditional knock-out (CKO) of connexin43 (Cx43), the major cardiac gap junction protein. While the Cx43 CKO mice have normal heart structure and contractile function, they die suddenly from spontaneous ventricular arrhythmias. Because abnormalities in gap junction expression in the diseased heart can be focal, we also generated chimeric mice formed from Cx43-null embryonic stem (ES) cells and wildtype recipient blastocysts. Heterogeneous Cx43 expression in the chimeric mice resulted in conduction defects and depressed contractile function. These novel genetic murine models of Cx43 loss of function in the adult mouse heart define gap junctional abnormalities as a key molecular feature of the arrhythmogenic substrate and an important factor in heart dysfunction
— id: 32705, year: 2001, vol: 8, page: 345, stat: Journal Article,

Conduction slowing and sudden arrhythmic death in mice with cardiac-restricted inactivation of connexin43
Gutstein DE; Morley GE; Tamaddon H; Vaidya D; Schneider MD; Chen J; Chien KR; Stuhlmann H; Fishman GI
2001 Feb 16;88(3):333-339, Circulation research
Cardiac arrhythmia is a common and often lethal manifestation of many forms of heart disease. Gap junction remodeling has been postulated to contribute to the increased propensity for arrhythmogenesis in diseased myocardium, although a causative role in vivo remains speculative. By generating mice with cardiac-restricted knockout of connexin43 (Cx43), we have circumvented the perinatal lethal developmental defect associated with germline inactivation of this gap junction channel gene and uncovered an essential role for Cx43 in the maintenance of electrical stability. Mice with cardiac-specific loss of Cx43 have normal heart structure and contractile function, and yet they uniformly (28 of 28 conditional Cx43 knockout mice observed) develop sudden cardiac death from spontaneous ventricular arrhythmias by 2 months of age. Optical mapping of the epicardial electrical activation pattern in Cx43 conditional knockout mice revealed that ventricular conduction velocity was significantly slowed by up to 55% in the transverse direction and 42% in the longitudinal direction, resulting in an increase in anisotropic ratio compared with control littermates (2.1+/-0.13 versus 1.66+/-0.06; P:<0.01). This novel genetic murine model of primary sudden cardiac death defines gap junctional abnormalities as a key molecular feature of the arrhythmogenic substrate
— id: 27670, year: 2001, vol: 88, page: 333, stat: Journal Article,

Heterogeneous expression of Gap junction channels in the heart leads to conduction defects and ventricular dysfunction
Gutstein DE; Morley GE; Vaidya D; Liu F; Chen FL; Stuhlmann H; Fishman GI
2001 Sep 4;104(10):1194-1199, Circulation
BACKGROUND:- Heterogeneous remodeling of gap junctions is observed in many forms of heart disease. The consequent loss of synchronous ventricular activation has been hypothesized to result in diminished cardiac performance. To directly test this hypothesis, we designed a murine model of heterogeneous gap junction channel expression. Methods and Results-- We generated chimeric mice formed from connexin43 (Cx43)-deficient embryonic stem cells and wild-type or genetically marked ROSA26 recipient blastocysts. Chimeric mice developed normally, without histological evidence of myocardial fibrosis or hypertrophy. Heterogeneous Cx43 expression resulted in conduction defects, however, as well as markedly depressed contractile function. Optical mapping of chimeric hearts by use of voltage-sensitive dyes revealed highly irregular epicardial conduction patterns, quantified as significantly greater negative curvature of the activation wave front (-1.86+/-0.40 mm in chimeric mice versus -0.86+/-0.098 mm in controls; P<0.01; n=6 for each group). Echocardiographic studies demonstrated significantly reduced fractional shortening in chimeric mice (26.6+/-2.3% versus 36.5+/-1.6% in age-matched 129/SvxC57BL/6F1 wild-type controls; P<0.05). CONCLUSIONS:- These data suggest that heterogeneous Cx43 expression, by perturbing the normal pattern of coordinated myocardial excitation, may directly depress cardiac performance
— id: 27669, year: 2001, vol: 104, page: 1194, stat: Journal Article,

Predicting plaque rupture: enhancing diagnosis and clinical decision-making in coronary artery disease
Fischer A; Gutstein DE; Fayad ZA; Fuster V
2000 ;5(3):163-172, Vascular medicine
Atherosclerosis is the process underlying coronary artery disease, myocardial infarction and cerebrovascular disease and is a leading cause of morbidity and mortality in industrialized countries. The atherosclerotic plaque is often indolent and progressive and may destabilize without warning. Components of the atherosclerotic plaque, including structural, cellular and molecular characteristics, determine its vulnerability to rupture. The imaging techniques currently available utilize invasive and non-invasive methods to characterize coronary artery stenoses. Detection, however, usually occurs late in the course of disease after symptoms have presented. Much effort has recently been directed at early detection and in defining markers of atherosclerotic disease. Our challenge for the future is to find non-invasive imaging modalities that can predict plaque vulnerability before irreversible damage has occurred. Through early detection and a targeted treatment strategy we hope to reduce the burden of ischemic heart disease
— id: 27763, year: 2000, vol: 5, page: 163, stat: Journal Article,

Thrombosis and coagulation abnormalities in the acute coronary syndromes
Fischer A; Gutstein DE; Fuster V
1999 May;17(2):283-94, viii, Cardiology clinics
The acute coronary syndromes, that include unstable angina, acute myocardial infarction, and many cases of sudden cardiac death, exact a considerable price on society in terms of mortality, morbidity, and health care costs. The coronary atherosclerotic lesion is often an indolent and progressive entity that can destabilize causing an acute syndrome with or without warning. The majority of acute coronary syndromes result from events such as rupture or disruption of the atherosclerotic plaque with intracoronary thrombosis and ischemia of the distal myocardium as a result. Advances in our understanding of the process underlying the acute coronary syndromes has allowed for the identification of targets and rational therapeutic strategies for the prevention and treatment of these syndromes. Many of these therapeutic strategies involve the reversal of prethrombotic forces that often coexist with coronary atherosclerosis. Even with recent advances in our approach to atherosclerosis, intracoronary thrombosis, and the resulting acute coronary syndromes, an unacceptably high event rate persists after these syndromes. Further advances in the prevention and treatment of coronary atherosclerosis and its thrombotic complications depends on a more thorough understanding of the biology of the atherosclerotic plaque and the factors which influence its stability
— id: 27764, year: 1999, vol: 17, page: 283, stat: Journal Article,

Pathophysiology and clinical significance of atherosclerotic plaque rupture
Gutstein DE; Fuster V
1999 Feb;41(2):323-333, Cardiovascular research
Atherosclerotic plaque rupture and resulting intracoronary thrombosis are thought to account for most acute coronary syndromes. These syndromes include unstable angina, non-Q-wave myocardial infarction (MI) and Q-wave MI. In addition, many cases of sudden cardiac death may be attributable to atherosclerotic plaque disruption and its immediate complications. Our understanding of the atherosclerotic process and the pathophysiology of plaque disruption has advanced remarkably. Despite these advances, event rates after acute coronary syndromes remain unacceptably high. This review will focus on the pathophysiology underlying atherosclerotic plaque development, the sequellae of coronary plaque rupture, and current therapies designed to treat the acute coronary syndromes. It is hoped that as our understanding of the atherosclerotic plaque improves, treatment strategies for the acute coronary syndromes will advance
— id: 27765, year: 1999, vol: 41, page: 323, stat: Journal Article,

Intracellular calcium release channel expression during embryogenesis
Rosemblit N; Moschella MC; Ondriasa E; Gutstein DE; Ondrias K; Marks AR
1999 Feb 15;206(2):163-177, Developmental biology (Orlando)
The release of intracellular calcium (Ca2+) via either inositol 1,4, 5-trisphosphate receptors (IP3R) or ryanodine receptors (RyR) activates a wide variety of signaling pathways in virtually every type of cell. In the present study we demonstrate that at early stages of development IP3R mRNA and functional IP3-gated Ca2+ release channels are widely expressed in virtually all tissues in murine embryos. As organogenesis proceeds, more specialized RyR channels are expressed in many cell types and the triggering mechanisms for intracellular Ca2+ release become more diverse to include IP3-dependent and voltage-dependent and Ca2+-induced Ca2+ release. As development proceeds virtually all cell types continue to express IP3R channels but in excitable cells including skeletal and cardiac muscles the major Ca2+ release channels are RyRs. This developmental switch from predominantly IP3-mediated to both IP3-mediated and IP3-independent pathways for intracellular Ca2+ release is consistent with data showing that IP3R plays an important regulatory role in cellular proliferation and apoptosis, whereas RyR is required for other cellular functions including muscle contraction
— id: 27766, year: 1999, vol: 206, page: 163, stat: Journal Article,

Pathophysiologic bases for adjunctive therapies in the treatment and secondary prevention of acute myocardial infarction
Gutstein DE; Fuster V
1998 Mar;21(3):161-168, Clinical cardiology
Postmyocardial infarction (MI) survival has been steadily improving. This improvement has been due, in part, to the actions of the adjunctive medical therapies for the treatment of MI. Aspirin, beta blockers, angiotensin-converting enzyme (ACE) inhibitors, and lipid-lowering agents have been shown to improve survival in the treatment and secondary prevention of MI. Nitrates have beneficial effects as well. These medications complement the reperfusion strategies through different mechanisms. Other adjunctive medical therapies, namely magnesium, antiarrhythmic agents, and calcium-channel blockers, have not been shown to improve mortality with routine post-MI use despite their theoretical benefits
— id: 27767, year: 1998, vol: 21, page: 161, stat: Journal Article,

Management of stable coronary artery disease
Gutstein DE; Fuster V
1997 Jul;56(1):99-106, 111, American family physician
Options for the treatment of multivessel coronary artery disease include medical therapy and revascularization with either coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA). CABG has been shown to prolong survival in patients with left main coronary disease or when at least two of the following factors are present: extensive coronary artery disease, significant ischemia as shown on stress testing and left ventricular dysfunction. In patients with extensive coronary artery disease but normal left ventricular function, either PTCA or CABG may be used initially without adversely affecting rates of survival. However, patients undergoing angioplasty have a higher rate of repeat revascularization procedures than those treated with bypass. The complex interplay of the various risks and benefits of medical therapy, angioplasty or bypass in the treatment of coronary artery disease requires an individualized approach to therapy and careful patient education
— id: 27770, year: 1997, vol: 56, page: 99, stat: Journal Article,

Role of inositol 1,4,5-trisphosphate receptors in regulating apoptotic signaling and heart failure
Gutstein DE; Marks AR
1997 ;Suppl 12(3):53-57, Heart vessels
The inositol 1,4,5-trisphosphate receptor (IP3R) is an endoplasmic reticular calcium release channel found in most cell types. Calcium signaling mediated by IP3Rs regulates a wide variety of physiological processes, including smooth muscle contraction, immune function, and fertility. We have focused on the role of the IP3R in programmed cell death and the regulation of IP3R levels in heart failure, a condition shown to be associated with cardiomyocyte apoptosis. During end-stage human heart failure, we have demonstrated that type 1 IP3R (IP3R1) mRNA and protein levels are up-regulated, in contrast to other cardiac calcium regulatory proteins, such as the type 2 ryanodine receptor (RYR2) and type IIa sarcoplasmic reticulum calcium adenosine triphosphatase (SERCA2), which are down-regulated. These data suggest that altered calcium channel expression may contribute to the defects in calcium homeostasis during heart failure. Furthermore, regulation of the IP3R may have implications for the survival of cardiac myocytes. Data from our laboratory have linked IP3R expression with susceptibility to apoptosis. IP3R-deficient T cells are resistant to apoptosis induced by dexamethasone, T cell receptor stimulation, ionizing radiation, and Fas. These findings suggest that intracellular calcium release via IP3Rs is a critical mediator of apoptosis. Thus the IP3R, which is up-regulated during human heart failure, may play a role in cardiomyocyte apoptosis and therefore in the pathophysiology of heart failure
— id: 27768, year: 1997, vol: Suppl 12, page: 53, stat: Journal Article,

Nontraumatic intramural hematoma of the duodenum complicating warfarin therapy
Gutstein DE; Rosenberg SJ
1997 Sep-Oct;64(4-5):339-341, Mount Sinai journal of medicine
A 74-year-old man receiving chronic anticoagulant therapy presented with symptoms of acute small bowel obstruction. He was subsequently found to have an intramural hematoma of the duodenum. Early noninvasive diagnosis was possible using computed tomography. Conservative therapy proved successful in allowing resolution of obstructive symptoms. This case illustrates the effectiveness of a conservative approach to intramural hematoma of the duodenum, even in patients requiring anticoagulation
— id: 27769, year: 1997, vol: 64, page: 339, stat: Journal Article,

Decreased inotropic but relatively preserved relaxation response to cyclic adenosine monophosphate-dependent agents in myopathic human myocardium
Gutstein DE; Flemmal K; Bruce E; Travers KE; Gwathmey JK; Ransil BJ; Markis JE; Grossman W; Morgan JP
1996 Dec;2(4):285-292, Journal of cardiac failure
BACKGROUND: Increased intracellular concentrations of cyclic adenosine monophosphate (AMP) stimulate a positive inotropic and lusitropic response in healthy myocardial tissue. Heart failure results in an attenuated inotropic response to cyclic AMP-dependent agents. This study compares the inotropic versus relaxation response to cyclic AMP-dependent and cyclic AMP-independent agents in myocardium from patients with end-stage heart failure and control patients without heart failure. METHODS AND RESULTS: Fifty-four control and 59 myopathic human ventricular trabeculae, 1 mm or less in diameter were placed in physiologic saline, 2.5 mM Ca2+, and stretched to the length at which maximal isometric force developed at 30 degrees C, 0.33 Hz. Dose-response curves plotted as percentage change from baseline versus concentration of drug were determined for acetylstrophanthidin, isoproterenol, isobutylmethylxanthine, and milrinone. Acetylstrophanthidin, a cyclic AMP-independent agent, showed similar increases in peak tension relative to baseline over the entire dose range tested for both control and myopathic heart muscle; its effect on relaxation of control and failing cardiac muscle was equivalent over the dose range tested. In contrast, the inotropic actions of the cyclic AMP-dependent agents, isoproterenol and the phosphodiesterase inhibitors, were significantly decreased in myopathic muscle compared with control muscle, but effects on relaxation in the control and myopathic groups remained relatively preserved. CONCLUSIONS: A relatively preserved relaxant effect is associated with the cyclic AMP-dependent agents, despite significant diminution of their inotropic effects. Thus, in advanced heart failure, patients may continue to benefit from the lusitropic effects of the cyclic AMP-dependent agents, even when the inotropic effects of these agents are severely attenuated
— id: 27771, year: 1996, vol: 2, page: 285, stat: Journal Article,

Abnormal myocardial calcium handling in the early stage of adriamycin cardiomyopathy
Kapelko VI; Williams CP; Gutstein DE; Morgan JP
1996 ;104(2):185-191, Archives of physiology & biochemistry
Metabolic changes have been shown to precede mechanical abnormalities in the early stages of adriamycin cardiotoxicity. This study examines the early changes in calcium homeostasis and their mechanical implications in a model of adriamycin cardiomyopathy. Hearts isolated from control and adriamycin-treated rats were coronary-perfused and isovolumic left ventricular (LV) pressure, coronary perfusion pressure and calcium transients from aequorin-loaded cardiomyocytes were recorded. Treated rats received three injections of adriamycin (6 mg/kg) for a period of 1 week. They were sacrificed for experiments 1-2 or 4-5 weeks after the final injection. The LV systolic and end-diastolic pressures were similar in both groups at varied external calcium concentrations (0.5-2.0 mM). However, systolic levels of myoplasmic calcium were substantially higher in the adriamycin-treated hearts, the difference being less at higher external calcium concentrations. Similar responses in both groups to paired pulse stimulation, increased stimulation frequency and caffeine (0.5-2.0 mM) were observed. However, adriamycin-treated hearts exhibited a smaller rise in LV developed pressure, as well as in systolic and diastolic calcium levels, in response to elevated coronary perfusion pressure. The elevated intracellular systolic calcium level is suggestive of an early but persistent effect of adriamycin on the calcium release channels of the sarcoplasmic reticulum. That the elevated systolic myoplasmic calcium levels are not accompanied by an increase in inotropy suggests a decrease in myofibrillar calcium sensitivity in this model of the early stage of adriamycin cardiomyopathy
— id: 27772, year: 1996, vol: 104, page: 185, stat: Journal Article,