Papers by Alessandra Moretti
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1994
With the aim of characterizing the functional and pharmacological properties of the different vol... more With the aim of characterizing the functional and pharmacological properties of the different voltage-dependent Ca2+ channels expressed in a given type of CNS neuron, we obtained single Ca2+ channel recordings from rat cerebellar granule cells in primary culture. Our data show that three novel classes of voltage-dependent Ca2+ channels are coexpressed in cerebellar granule cells. They are pharmacologically distinct from dihydropyridine-sensitive L-type and omega-conotoxin-sensitive N-type channels, and their functional properties are different from those of P- and T-type channels. The three novel 21 pS G1-, 15 pS G2-, and 20 pS G3-type Ca2+ channels have similar inactivation properties. They show complete steady-state inactivation at -40 mV and their single-channel average currents have both sustained and decaying components. They differ in activation threshold (-40 mV for G2, -30 mV for G3, and -10 mV for G1, with 90 mM Ba2+ as charge carrier), mean open time (1.2 msec for G2, 1 ms...
International Journal of Molecular Sciences, 2015
Membrane potentials display the cellular status of non-excitable cells and mediate communication ... more Membrane potentials display the cellular status of non-excitable cells and mediate communication between excitable cells via action potentials. The use of genetically encoded biosensors employing fluorescent proteins allows a non-invasive biocompatible way to read out the membrane potential in cardiac myocytes and other cells of the circulation system. Although the approaches to design such biosensors date back to the time when the first fluorescent-protein based Förster Resonance Energy Transfer (FRET) sensors were constructed, it took 15 years before reliable sensors became readily available. Here, we review OPEN ACCESS Int. J. Mol. Sci. 2015, 16 21627 different developments of genetically encoded membrane potential sensors. Furthermore, it is shown how such sensors can be used in pharmacological screening applications as well as in circulation related basic biomedical research. Potentials and limitations will be discussed and perspectives of possible future developments will be provided.
Biophysical Journal, 2014
ABSTRACT Background: De novo mutations in calmodulin genes have been recently associated with mar... more ABSTRACT Background: De novo mutations in calmodulin genes have been recently associated with markedly prolonged QT interval and life-threatening ventricular arrhythmias in infants. Biochemical evidences suggested impaired calcium ion binding to mutant calmodulins. Calcium dependent inactivation (CDI) of L-type calcium channel (ICaL) involves the interaction between Ca2+-calmodulin and the channel protein. Aims: To explore the effects of two CALM1 mutations (F142L and D130G) on electrical activity and ICaL properties in human induced-pluripotent stem cells (iPSC)-derived cardiomyocytes (CM). Methods: Skin fibroblasts of two patients carrying the mutation CALM1-F142L or CALM1-D130G were reprogrammed to generate iPSC and these cells differentiated into CM; a healthy donor was selected as control. Two cell clones for each mutation were analyzed to rule out clone specificity. Patch clamp and micro electrode arrays (MEA) analyses were performed on isolated iPSC-derived CM and beating clusters at about 40 days of differentiation respectively. ICaL was isolated in the presence of calcium or barium ions as charge carriers. Results: CALM1-F142L iPSC-derived CM showed prolonged field potential duration (FPD) with high beta-adrenergic sensitivity; peak ICaL density was unaltered, but CDI was markedly reduced and inactivation incomplete. CALM1-D130G iPSC-derived CM showed higher ICaL density and unaltered CDI. Conclusions: F142L and D130G calmodulin mutations differently affect ICaL properties in human iPSC-derived CM. F142L mutation is consistent with reduced calcium affinity of calmodulin; D130G abnormality suggests ICaL facilitation instead, possibly resulting from upregulation of alternative calmodulin isoforms. Overall, both calmodulin mutations might potentially cause arrhythmogenic calcium overload.
La Radiologia medica, 2006
Metastatic cancers of unknown primary origin are characterised by a poor prognosis, with a surviv... more Metastatic cancers of unknown primary origin are characterised by a poor prognosis, with a survival rate from diagnosis of approximately 12 months. Conventional radiological imaging allows detection of 20%-27% of primary cancers, whereas the detection rate with positron emission tomography (PET) is 24%-40%. The aim of this study was to assess the role of 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) in the identification of occult primary cancers. The study population consisted of 38 consecutive patients with histologically proven metastatic disease and negative or nonconclusive conventional diagnostic procedures. All patients were studied by 18F-FDG PET performed according to the standard procedure (6 h of fasting, intravenous injection of 370 MBq 18F-FDG, and image acquisition with a PET/CT scanner for 4 min per bed position). 18F-FDG-PET/CT detected the occult primary cancer in 20 cases (53%), showing higher sensitivity than that reported for any other imaging modalit...
Molecular and Cellular Neuroscience, 2010
Journal of Clinical Microbiology, 2009
The BD Phoenix system was compared to the cefoxitin disk diffusion test for detection of methicil... more The BD Phoenix system was compared to the cefoxitin disk diffusion test for detection of methicillin (meticillin) resistance in 1,066 Staphylococcus aureus and 1,121 coagulase-negative staphylococcus (CoNS) clinical isolates. The sensitivity for Phoenix was 100%. The specificities were 99.86% for S. aureus and 88.4% for CoNS.
Human Gene Therapy, 2001
Cardiac myocyte apoptosis has been demonstrated in end-stage failing human hearts. The therapeuti... more Cardiac myocyte apoptosis has been demonstrated in end-stage failing human hearts. The therapeutic utility of blocking apoptosis in congestive heart failure (CHF) has not been elucidated. This study investigated the role of caspase activation in cardiac contractility and sarcomere organization in the development of CHF. In a rabbit model of heart failure obtained by rapid ventricular pacing, we demonstrate, using in vivo transcoronary adenovirus-mediated gene delivery of the potent caspase inhibitor p35, that caspase activation is associated with a reduction in contractile force of failing myocytes by destroying sarcomeric structure. In this animal model gene transfer of p35 prevented the rise in caspase 3 activity and DNA-histone formation. Genetically manipulated hearts expressing p35 had a significant improvement in left ventricular pressure rise (+dp/dt), decreased end-diastolic chamber pressure (LVEDP), and the development of heart failure was delayed. To better understand this benefit, we examined the effects of caspase 3 on cardiomyocyte dysfunction in vitro. Microinjection of activated caspase 3 into the cytoplasm of intact myocytes induced sarcomeric disorganization and reduced contractility of the cells. These results demonstrate a direct impact of caspases on cardiac function and may lead to novel therapeutic strategies via antiapoptotic regimens.
EMBO Molecular Medicine, 2012
Coordinated release of calcium (Ca 2þ ) from the sarcoplasmic reticulum (SR) through cardiac ryan... more Coordinated release of calcium (Ca 2þ ) from the sarcoplasmic reticulum (SR) through cardiac ryanodine receptor (RYR2) channels is essential for cardiomyocyte function. In catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited disease characterized by stress-induced ventricular arrhythmias in young patients with structurally normal hearts, autosomal dominant mutations in RYR2 or recessive mutations in calsequestrin lead to aberrant diastolic Ca 2þ release from the SR causing arrhythmogenic delayed after depolarizations (DADs). Here, we report the generation of induced pluripotent stem cells (iPSCs) from a CPVT patient carrying a novel RYR2 S406L mutation. In patient iPSC-derived cardiomyocytes, catecholaminergic stress led to elevated diastolic Ca 2þ concentrations, a reduced SR Ca 2þ content and an increased susceptibility to DADs and arrhythmia as compared to control myocytes. This was due to increased frequency and duration of elementary Ca 2þ release events (Ca 2þ sparks). Dantrolene, a drug effective on malignant hyperthermia, restored normal Ca 2þ spark properties and rescued the arrhythmogenic phenotype. This suggests defective inter-domain interactions within the RYR2 channel as the pathomechanism of the S406L mutation. Our work provides a new in vitro model to study the pathogenesis of human cardiac arrhythmias and develop novel therapies for CPVT.
Current Stem Cell Research & Therapy, 2014
Circulation, 2000
Systemic levels of arginine vasopressin (AVP) are increased in congestive heart failure, resultin... more Systemic levels of arginine vasopressin (AVP) are increased in congestive heart failure, resulting in vasoconstriction and reduced cardiac contractility via V(1) vasopressin receptors. V(2) vasopressin receptors (V2Rs), which promote activation of adenylyl cyclase, are physiologically expressed only in the kidney and are absent in the myocardium. Heterologous expression of V2Rs in the myocardium could result in a positive inotropic effect by using the endogenous high concentrations of AVP in heart failure. We tested gene transfer with a recombinant adenovirus for the human V2R (Ad-V2R) to stimulate contractility of rat or rabbit myocardium in vivo. Ultrasound-guided direct injection or transcoronary delivery of adenovirus in vivo resulted in recombinant receptor expression in the myocardial target area, leading to a substantial increase in [(3)H]AVP binding. In 50% of the cardiomyocytes isolated from the directly injected area, single-cell shortening measurements detected a significant increase in contraction amplitude after exposure to AVP or the V2R-specific desmopressin (DDAVP). Echocardiography of the target myocardial area documented a marked increase in local fractional shortening after systemic administration of DDAVP in V2R-expressing animals but not in control virus-treated hearts. Simultaneous measurement of global contractility (dP/dt(max)) confirmed a positive inotropic effect of DDAVP on left ventricular function in the Ad-V2R-injected animals. Adenoviral gene transfer of the V2R into the myocardium increases cardiac contractility in vivo. Heterologous expression of cAMP-forming receptors in the myocardium could lead to novel strategies in the therapy of congestive heart failure by bypassing the desensitized beta-adrenergic receptor-signaling cascade.
AJP: Heart and Circulatory Physiology, 2014
Developmental Cell, Dec 1, 2010
Like transcription factors, microRNAs are emerging as regulators of cell fate decisions. In this ... more Like transcription factors, microRNAs are emerging as regulators of cell fate decisions. In this issue, Wang et al. (2010) identify a critical microRNA pathway under the control of Bmp signaling that promotes outflow tract myocardial differentiation from cardiac progenitors in vivo.
Cell Stem Cell, Aug 16, 2007
Isl1 + cardiovascular progenitors and their downstream progeny play a pivotal role in cardiogenes... more Isl1 + cardiovascular progenitors and their downstream progeny play a pivotal role in cardiogenesis and lineage diversification of the heart. The mechanisms that control their renewal and differentiation are largely unknown. Herein, we show that the Wnt/b-catenin pathway is a major component by which cardiac mesenchymal cells modulate the prespecification, renewal, and differentiation of isl1 + cardiovascular progenitors. This microenvironment can be reconstituted by a Wnt3a-secreting feeder layer with ES cell-derived, embryonic, and postnatal isl1 + cardiovascular progenitors. In vivo activation of b-catenin signaling in isl1 + progenitors of the secondary heart field leads to their massive accumulation, inhibition of differentiation, and outflow tract (OFT) morphogenic defects. In addition, the mitosis rate in OFT myocytes is significantly reduced following b-catenin deletion in isl1 + precursors. Agents that manipulate Wnt signals can markedly expand isl1 + progenitors from human neonatal hearts, a key advance toward the cloning of human isl1 + heart progenitors.
Stem Cells and Cancer Stem Cells, Volume 9, 2012
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Papers by Alessandra Moretti