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Search Results: 1 - 10 of 2011 matches for " Silvio Litovsky "
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Aspectos fisiopatológicos y moleculares en la remodelación de la matriz extracelular vascular
Erijman,Mauricio O.; Litovsky,Silvio;
Revista argentina de cardiolog?-a , 2007,
Abstract: in arterial remodeling, as well as in various body tissues, the extracellular matrix plays an important role. remodeling is a phenomenon which is difficult to reproduce experimentally because the makeup of the matrix is complex. in the case of arteries, a key factor is the change in the smooth muscle-matrix relation, which causes the phenotype of the smooth muscle to change from contractile to secretory. for the changes to occur in the matrix and smooth muscle, the activation of protease-encoding genes is essential, since they modify the cell-cell and cell-matrix relations.
Aspectos fisiopatológicos y moleculares en la remodelación de la matriz extracelular vascular
Mauricio O. Erijman,Silvio Litovsky
Revista Argentina de Cardiología , 2007,
Abstract: cumple un papel importante. La complejidad en la constitución de la matriz hace de la remodelación un fenómeno difícil de reproducir experimentalmente. En el caso de las arterias es clave la modificación de la relación músculo liso-matriz que produzca el cambio en el músculo liso del fenotipo contráctil al secretor.Para que ocurran los cambios en la matriz y en el músculo liso es determinante la activación de los genes productores de las proteasas que modificarán las relaciones célula-célula y célula-matriz.
Interaural Level Differences Do Not Suffice for Restoring Spatial Release from Masking in Simulated Cochlear Implant Listening
Antje Ihlefeld, Ruth Y. Litovsky
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045296
Abstract: Spatial release from masking refers to a benefit for speech understanding. It occurs when a target talker and a masker talker are spatially separated. In those cases, speech intelligibility for target speech is typically higher than when both talkers are at the same location. In cochlear implant listeners, spatial release from masking is much reduced or absent compared with normal hearing listeners. Perhaps this reduced spatial release occurs because cochlear implant listeners cannot effectively attend to spatial cues. Three experiments examined factors that may interfere with deploying spatial attention to a target talker masked by another talker. To simulate cochlear implant listening, stimuli were vocoded with two unique features. First, we used 50-Hz low-pass filtered speech envelopes and noise carriers, strongly reducing the possibility of temporal pitch cues; second, co-modulation was imposed on target and masker utterances to enhance perceptual fusion between the two sources. Stimuli were presented over headphones. Experiments 1 and 2 presented high-fidelity spatial cues with unprocessed and vocoded speech. Experiment 3 maintained faithful long-term average interaural level differences but presented scrambled interaural time differences with vocoded speech. Results show a robust spatial release from masking in Experiments 1 and 2, and a greatly reduced spatial release in Experiment 3. Faithful long-term average interaural level differences were insufficient for producing spatial release from masking. This suggests that appropriate interaural time differences are necessary for restoring spatial release from masking, at least for a situation where there are few viable alternative segregation cues.
Differentiation of acute and four-week old myocardial infarct with Gd(ABE-DTTA)-enhanced CMR
Robert Kirschner, Levente Toth, Akos Varga-Szemes, Tamas Simor, Pal Suranyi, Pal Kiss, Balazs Ruzsics, Attila Toth, Robert Baker, Brigitta C Brott, Silvio Litovsky, Ada Elgavish, Gabriel A Elgavish
Journal of Cardiovascular Magnetic Resonance , 2010, DOI: 10.1186/1532-429x-12-22
Abstract: Dogs (n = 6) were studied in a closed-chest, reperfused, double myocardial infarct model. Myocardial infarcts were generated by occluding the Left Anterior Descending (LAD) coronary artery with an angioplasty balloon for 180 min, and four weeks later occluding the Left Circumflex (LCx) coronary artery for 180 min. LE images were obtained on day 3 and day 4 after second myocardial infarct, using Gd(DTPA) (standard extracellular contrast agent) and Gd(ABE-DTTA) (new, low molecular weight contrast agent), respectively. Triphenyltetrazolium chloride (TTC) histomorphometry validated existence and location of infarcts. Hematoxylin-eosin and Masson's trichrome staining provided histologic evaluation of infarcts.Gd(ABE-DTTA) or Gd(DTPA) highlighted the acute infarct, whereas the four-week old infarct was visualized by Gd(DTPA), but not by Gd(ABE-DTTA). With Gd(ABE-DTTA), the mean ± SD signal intensity enhancement (SIE) was 366 ± 166% and 24 ± 59% in the acute infarct and the four-week old infarct, respectively (P < 0.05). The latter did not differ significantly from signal intensity in healthy myocardium (P = NS). Gd(DTPA) produced signal intensity enhancements which were similar in acute (431 ± 124%) and four-week old infarcts (400 ± 124%, P = NS), and not statistically different from the Gd(ABE-DTTA)-induced SIE in acute infarct. The existence and localization of both infarcts were confirmed by triphenyltetrazolium chloride (TTC). Histologic evaluation demonstrated coagulation necrosis, inflammation, and multiple foci of calcification in the four day old infarct, while the late subacute infarct showed granulation tissue and early collagen deposition.Late enhancement CMR with separate administrations of standard extracellular contrast agent, Gd(DTPA), and the new low molecular weight contrast agent, Gd(ABE-DTTA), differentiates between acute and late subacute infarct in a reperfused, double infarct, canine model.Reinfarction occurs in 7-8% of cardiac patients with previous
Anti-Inflammatory Mechanisms of Apolipoprotein A-I Mimetic Peptide in Acute Respiratory Distress Syndrome Secondary to Sepsis
Oleg F. Sharifov, Xin Xu, Amit Gaggar, William E. Grizzle, Vinod K. Mishra, Jaideep Honavar, Silvio H. Litovsky, Mayakonda N. Palgunachari, C. Roger White, G. M. Anantharamaiah, Himanshu Gupta
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064486
Abstract: Acute respiratory distress syndrome (ARDS) due to sepsis has a high mortality rate with limited treatment options. High density lipoprotein (HDL) exerts innate protective effects in systemic inflammation. However, its role in ARDS has not been well studied. Peptides such as L-4F mimic the secondary structural features and functions of apolipoprotein (apo)A-I, the major protein component of HDL. We set out to measure changes in HDL in sepsis-mediated ARDS patients, and to study the potential of L-4F to prevent sepsis-mediated ARDS in a rodent model of lipopolysaccharide (LPS)-mediated acute lung injury, and a combination of primary human leukocytes and human ARDS serum. We also analyzed serum from non-lung disease intubated patients (controls) and sepsis-mediated ARDS patients. Compared to controls, ARDS demonstrates increased serum endotoxin and IL-6 levels, and decreased HDL, apoA-I and activity of anti-oxidant HDL-associated paraoxanase-1. L-4F inhibits the activation of isolated human leukocytes and neutrophils by ARDS serum and LPS in vitro. Further, L-4F decreased endotoxin activity and preserved anti-oxidant properties of HDL both in vitro and in vivo. In a rat model of severe endotoxemia, L-4F significantly decreased mortality and reduces lung and liver injury, even when administered 1 hour post LPS. Our study suggests the protective role of the apoA-I mimetic peptide L-4F in ARDS and gram-negative endotoxemia and warrant further clinical evaluation. The main protective mechanisms of L-4F are due to direct inhibition of endotoxin activity and preservation of HDL anti-oxidant activity.
Chymase Mediates Injury and Mitochondrial Damage in Cardiomyocytes during Acute Ischemia/Reperfusion in the Dog
Junying Zheng, Chih-Chang Wei, Naoki Hase, Ke Shi, Cheryl R. Killingsworth, Silvio H. Litovsky, Pamela C. Powell, Tsunefumi Kobayashi, Carlos M. Ferrario, Andras Rab, Inmaculada Aban, James F. Collawn, Louis J. Dell'Italia
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094732
Abstract: Cardiac ischemia and reperfusion (I/R) injury occurs because the acute increase in oxidative/inflammatory stress during reperfusion culminates in the death of cardiomyocytes. Currently, there is no drug utilized clinically that attenuates I/R injury in patients. Previous studies have demonstrated degranulation of mast cell contents into the interstitium after I/R. Using a dog model of I/R, we tested the role of chymase, a mast cell protease, in cardiomyocyte injury using a specific oral chymase inhibitor (CI). 15 adult mongrel dogs had left anterior descending artery occlusion for 60 min and reperfusion for 100 minutes. 9 dogs received vehicle and 6 were pretreated with a specific CI. In vivo cardiac microdialysis demonstrated a 3-fold increase in interstitial fluid chymase activity in I/R region that was significantly decreased by CI. CI pretreatment significantly attenuated loss of laminin, focal adhesion complex disruption, and release of troponin I into the circulation. Microarray analysis identified an I/R induced 17-fold increase in nuclear receptor subfamily 4A1 (NR4A1) and significantly decreased by CI. NR4A1 normally resides in the nucleus but can induce cell death on migration to the cytoplasm. I/R caused significant increase in NR4A1 protein expression and cytoplasmic translocation, and mitochondrial degradation, which were decreased by CI. Immunohistochemistry also revealed a high concentration of chymase within cardiomyocytes after I/R. In vitro, chymase added to culture HL-1 cardiomyocytes entered the cytoplasm and nucleus in a dynamin-dependent fashion, and promoted cytoplasmic translocation of NR4A1 protein. shRNA knockdown of NR4A1 on pre-treatment of HL-1 cells with CI significantly decreased chymase-induced cell death and mitochondrial damage. These results suggest that the beneficial effects of an orally active CI during I/R are mediated in the cardiac interstitium as well as within the cardiomyocyte due to a heretofore-unrecognized chymase entry into cardiomyocytes.
From school to dentist’s surgery: prevention measures on the six-year-old children
Villaumé C,Litovsky B,Witczak I,Roché E
Pratiques et Organisation des Soins , 2010,
Abstract: Aim: The aim of this study is to assess health impact and determine the limitations of a support policy in oral prevention on the six- year-old children sent to school in education help areas. Methods: This analysis concerns an action of the french Gard department which has set up a short and incentive circuit going from the raising awareness to the oral examination (EBD), and until care if necessary. That action lies within the framework of the national program “M’T dents”. The measures focussed on 624 children irrespective of social security system. Results: The children’s participation rate in the EBD is significantly superior to the departmental rate observed (28% vs 51,2%, N = 624). The medical assessment performed shows that 55,9% of the 188 children from the general social security system concerned with EBD are free of caries and a not homogeneous distribution of theC mixed index at the time of the screening. The percentage of untreated children (IT indicator) falls after the measures (33,5% vs 10,1%, N = 188, p < 0,001), while the completely cured children increases (7,5% vs 36,7%, N = 188, p < 0,001) at the same time. Conclusion: The evolution “before/after” of the index and indicators values reveals a significant increase in access to screening and care. Nevertheless, there are still children remaining outside the healthcare system. For them, the question of additional measures arises. Prat Organ Soins. 2010;41(4):303-311
Backward Reachability of Array-based Systems by SMT solving: Termination and Invariant Synthesis
Silvio Ghilardi,Silvio Ranise
Computer Science , 2010, DOI: 10.2168/LMCS-6(4:10)2010
Abstract: The safety of infinite state systems can be checked by a backward reachability procedure. For certain classes of systems, it is possible to prove the termination of the procedure and hence conclude the decidability of the safety problem. Although backward reachability is property-directed, it can unnecessarily explore (large) portions of the state space of a system which are not required to verify the safety property under consideration. To avoid this, invariants can be used to dramatically prune the search space. Indeed, the problem is to guess such appropriate invariants. In this paper, we present a fully declarative and symbolic approach to the mechanization of backward reachability of infinite state systems manipulating arrays by Satisfiability Modulo Theories solving. Theories are used to specify the topology and the data manipulated by the system. We identify sufficient conditions on the theories to ensure the termination of backward reachability and we show the completeness of a method for invariant synthesis (obtained as the dual of backward reachability), again, under suitable hypotheses on the theories. We also present a pragmatic approach to interleave invariant synthesis and backward reachability so that a fix-point for the set of backward reachable states is more easily obtained. Finally, we discuss heuristics that allow us to derive an implementation of the techniques in the model checker MCMT, showing remarkable speed-ups on a significant set of safety problems extracted from a variety of sources.
Realismo e interpretación
Pinto,Silvio;
EPISTEME , 2006,
Abstract: en este trabajo intento mostrar, en primer lugar, que el realismo interno de hilary putnam no logra explicar filosóficamente la determinación de la referencia de las expresiones del lenguaje cotidiano. en segundo lugar, sugiero una explicación alternativa de la determinación de la referencia apelando al concepto de interpretación radical; además, el enfoque interpretativo lo voy a concebir como una variante del realismo. finalmente, sugiero que un tipo de enfoque interpretativo está presente en la filosofía del segundo wittgenstein.
Biogeochemistry of the OMZ of Chile
Pantoja,Silvio;
Gayana (Concepción) , 2006, DOI: 10.4067/S0717-65382006000300013
Abstract: most microbial reactions are in one way or another associated to decomposition of organic matter, and occurs under two general conditions: in the presence and in the absence of oxygen. here, we will examine current information on the biogeochemical reactions in the area of the oxygen minimum zone off chile. the aim of this presentation is to examine mechanisms of processing of organic matter under upwelling and o2 depletion.
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