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Search Results: 1 - 10 of 7480 matches for " Claudio Iaconetti "
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Non-Coding RNAs: The “Dark Matter” of Cardiovascular Pathophysiology
Claudio Iaconetti,Clarice Gareri,Alberto Polimeni,Ciro Indolfi
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms141019987
Abstract: Large-scale analyses of mammalian transcriptomes have identified a significant number of different RNA molecules that are not translated into protein. In fact, the use of new sequencing technologies has identified that most of the genome is transcribed, producing a heterogeneous population of RNAs which do not encode for proteins (ncRNAs). Emerging data suggest that these transcripts influence the development of cardiovascular disease. The best characterized non-coding RNA family is represented by short highly conserved RNA molecules, termed microRNAs (miRNAs), which mediate a process of mRNA silencing through transcript degradation or translational repression. These microRNAs (miRNAs) are expressed in cardiovascular tissues and play key roles in many cardiovascular pathologies, such as coronary artery disease (CAD) and heart failure (HF). Potential links between other ncRNAs, like long non-coding RNA, and cardiovascular disease are intriguing but the functions of these transcripts are largely unknown. Thus, the functional characterization of ncRNAs is essential to improve the overall understanding of cellular processes involved in cardiovascular diseases in order to define new therapeutic strategies. This review outlines the current knowledge of the different ncRNA classes and summarizes their role in cardiovascular development and disease.
MicroRNA-1 Downregulation Increases Connexin 43 Displacement and Induces Ventricular Tachyarrhythmias in Rodent Hypertrophic Hearts
Antonio Curcio, Daniele Torella, Claudio Iaconetti, Eugenia Pasceri, Jolanda Sabatino, Sabato Sorrentino, Salvatore Giampà, Mariella Micieli, Alberto Polimeni, Beverley J. Henning, Angelo Leone, Daniele Catalucci, Georgina M. Ellison, Gianluigi Condorelli, Ciro Indolfi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070158
Abstract: Downregulation of the muscle-specific microRNA-1 (miR-1) mediates the induction of pathologic cardiac hypertrophy. Dysfunction of the gap junction protein connexin 43 (Cx43), an established miR-1 target, during cardiac hypertrophy leads to ventricular tachyarrhythmias (VT). However, it is still unknown whether miR-1 and Cx43 are interconnected in the pro-arrhythmic context of hypertrophy. Thus, in this study we investigated whether a reduction in the extent of cardiac hypertrophy could limit the pathological electrical remodeling of Cx43 and the onset of VT by modulating miR-1 levels. Wistar male rats underwent mechanical constriction of the ascending aorta to induce pathologic left ventricular hypertrophy (LVH) and afterwards were randomly assigned to receive 10mg/kg valsartan, VAL (LVH+VAL) delivered in the drinking water or placebo (LVH) for 12 weeks. Sham surgery was performed for control groups. Programmed ventricular stimulation reproducibly induced VT in LVH compared to LVH+VAL group. When compared to sham controls, rats from LVH group showed a significant decrease of miR-1 and an increase of Cx43 expression and its ERK1/2-dependent phosphorylation, which displaces Cx43 from the gap junction. Interestingly, VAL administration to rats with aortic banding significantly reduced cardiac hypertrophy and prevented miR-1 down-regulation and Cx43 up-regulation and phosphorylation. Gain- and loss-of-function experiments in neonatal cardiomyocytes (NCMs) in vitro confirmed that Cx43 is a direct target of miR-1. Accordingly, in vitro angiotensin II stimulation reduced miR-1 levels and increased Cx43 expression and phosphorylation compared to un-stimulated NCMs. Finally, in vivo miR-1 cardiac overexpression by an adenoviral vector intra-myocardial injection reduced Cx43 expression and phosphorylation in mice with isoproterenol-induced LVH. In conclusion, miR-1 regulates Cx43 expression and activity in hypertrophic cardiomyocytes in vitro and in vivo. Treatment of pressure overload-induced myocyte hypertrophy reduces the risk of life-threatening VT by normalizing miR-1 expression levels with the consequent stabilization of Cx43 expression and activity within the gap junction.
Evaluational Brainstorming  [PDF]
Claudio Bezzi
Sociology Mind (SM) , 2011, DOI: 10.4236/sm.2011.14019
Abstract: Among the evaluation techniques based upon group queries (e.g. focus group), brainstorming does not enjoy particular consideration. This might be the result of its origin and development within organizational and managerial domains, traditionally focused more on “idea production” (and problem solving) than on idea analysis within the context of evaluational and social research. This paper presents a development of classical brainstorming, which is quite useful to evaluation, where the traditional idea-producing step is followed by group analysis and exploration of the shared evaluand-specific semantic space. This evaluational brainstorming is the result of a shared understanding of the evaluand by different stakeholders, who can now ascertain their goals and draw cognitive maps to guide subsequent methodological choices and data gathering requirements.
PC-VAR Estimation of Vector Autoregressive Models  [PDF]
Claudio Morana
Open Journal of Statistics (OJS) , 2012, DOI: 10.4236/ojs.2012.23030
Abstract: In this paper PC-VAR estimation of vector autoregressive models (VAR) is proposed. The estimation strategy successfully lessens the curse of dimensionality affecting VAR models, when estimated using sample sizes typically available in quarterly studies. The procedure involves a dynamic regression using a subset of principal components extracted from a vector time series, and the recovery of the implied unrestricted VAR parameter estimates by solving a set of linear constraints. PC-VAR and OLS estimation of unrestricted VAR models show the same asymptotic properties. Monte Carlo results strongly support PC-VAR estimation, yielding gains, in terms of both lower bias and higher efficiency, relatively to OLS estimation of high dimensional unrestricted VAR models in small samples. Guidance for the selection of the number of components to be used in empirical studies is provided.
Numeric Solution of the Fokker-Planck-Kolmogorov Equation  [PDF]
Claudio Floris
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.512119
Abstract:

The solution of an n-dimensional stochastic differential equation driven by Gaussian white noises is a Markov vector. In this way, the transition joint probability density function (JPDF) of this vector is given by a deterministic parabolic partial differential equation, the so-called Fokker-Planck-Kolmogorov (FPK) equation. There exist few exact solutions of this equation so that the analyst must resort to approximate or numerical procedures. The finite element method (FE) is among the latter, and is reviewed in this paper. Suitable computer codes are written for the two fundamental versions of the FE method, the Bubnov-Galerkin and the Petrov-Galerkin method. In order to reduce the computational effort, which is to reduce the number of nodal points, the following refinements to the method are proposed: 1) exponential (Gaussian) weighting functions different from the shape functions are tested; 2) quadratic and cubic splines are used to interpolate the nodal values that are known in a limited number of points. In the applications, the transient state is studied for first order systems only, while for second order systems, the steady-state JPDF is determined, and it is compared with exact solutions or with simulative solutions: a very good agreement is found.

Factor Vector Autoregressive Estimation of Heteroskedastic Persistent and Non Persistent Processes Subject to Structural Breaks  [PDF]
Claudio Morana
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.44030
Abstract:

In the paper, a general framework for large scale modeling of macroeconomic and financial time series is introduced. The proposed approach is characterized by simplicity of implementation, performing well independently of persistence and heteroskedasticity properties, accounting for common deterministic and stochastic factors. Monte Carlo results strongly support the proposed methodology, validating its use also for relatively small cross-sectional and temporal samples.

A Quantum Field Theory Description of Separate Electric and Magnetic Effects in Elementary Fermion Epigenetics  [PDF]
Claudio Verzegnassi
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.61011
Abstract: The separate effects that an electric and a magnetic field would have on the total energy and spin of an elementary electron state have been computed in a theoretical quantum field theory framework. It is shown that all the effects in this process, that are defined “fermion epigenetics”, can be expressed in a simple and elegant way in terms of the components of the electron field, called “psinons” in this approach. In the minimal interaction prescription, the electric and the magnetic effects can be separated into the sum of “classical” components reproducing conventional Stark and Zeeman effects, and new components of different type. In the non-relativistic limit, the two residual effects on the energy only depend on the electron intrinsic properties, i.e. its charge and its spin, and on the value of the electric and magnetic potentials. A comparison with the results obtainable in a Pauli formalism approach is discussed and, finally, a very qualitative calculation of the size of possible effects is performed.
Mactare. Etymology and Anthropology of the Archaic Sacred  [PDF]
Claudio Tugnoli
Open Journal of Philosophy (OJPP) , 2015, DOI: 10.4236/ojpp.2015.56044
Abstract: In this article I will show that the victimary theory of René Girard can make a decisive contribution to the interpretation and solution of etymological and semantic questions of the verb “mactare”, which is basic in the terminology related to the topic of the sacrifice. The victimary anthropology provides the hermeneutical key that allows us to consider the expressions “mactare Deum” and “mactare victimam” as genetically synonymous. The theory of René Girard seems to perfectly explain the coexistence, in “mactare victimam”, of two meanings: kill on the one hand, raise and glorify on the other hand. In the case of original lynching, which is mostly hidden in the myth, the victim, which at first is killed for it is believed that the cause of all evils is deified by the persecutors as the cause of all goods. Hence the need to strengthen and renew periodically, through animals or human sacrifices, the saving power of divinity established with the murder of the first victim. That’s why killing and glorifying coexist in “mactare”, which is both “mactare victimam” and “mactare Deum”, since the verb means to kill when referring to a victim and to glorify when referring to God. Indeed, the deification of the victim is the result of his killing.
Semiparametric Estimation of Multivariate GARCH Models  [PDF]
Claudio Morana
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.57083
Abstract:

The paper introduces a new simple semiparametric estimator of the conditional variance-covariance and correlation matrix (SP-DCC). While sharing a similar sequential approach to existing dynamic conditional correlation (DCC) methods, SP-DCC has the advantage of not requiring the direct parameterization of the conditional covariance or correlation processes, therefore also avoiding any assumption on their long-run target. In the proposed framework, conditional variances are estimated by univariate GARCH models, for actual and suitably transformed series, in the first step; the latter are then nonlinearly combined in the second step, according to basic properties of the covariance and correlation operator, to yield nonparametric estimates of the various conditional covariances and correlations. Moreover, in contrast to available DCC methods, SP-DCC allows for straightforward estimation also for the non-symultaneous case, i.e. for the estimation of conditional cross-covariances and correlations, displaced at any time horizon of interest. A simple expost procedure to ensure well behaved conditional variance-covariance and correlation matrices, grounded on nonlinear shrinkage, is finally proposed. Due to its sequential implementation and scant computational burden, SP-DCC is very simple to apply and suitable for the modeling of vast sets of conditionally heteroskedastic time series.

Model Averaging by Stacking  [PDF]
Claudio Morana
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.57079
Abstract:

The paper introduces a new Frequentist model averaging estimation procedure, based on a stacked OLS estimator across models, implementable on cross-sectional, panel, as well as time series data. The proposed estimator shows the same optimal properties of the OLS estimator under the usual set of assumptions concerning the population regression model. Relatively to available alternative approaches, it has the advantage of performing model averaging exante in a single step, optimally selecting models’ weight according to the MSE metric, i.e. by minimizing the squared Euclidean distance between actual and predicted value vectors. Moreover, it is straightforward to implement, only requiring the estimation of a single OLS augmented regression. By exploiting exante a broader information set and benefiting of more degrees of freedom, the proposed approach yields more accurate and (relatively) more efficient estimation than available expost methods.

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