83 research outputs found
”Fluvastatin treatment inhibits leucocyte adhesion and extravasation in models of complement-mediated acute inflamation”F.Fischetti, R. Carretta, G. Borotto, P. Durigutto, R. Bulla, P.L. Meroni, F. Tedesco.
No full textAbstract
Complement activation plays a relevant role in the development of tissue damage under inflammatory conditions, and clinical and experimental observations emphasize its contribution to inflammatory vasculitides. Statins have recently been shown to reduce cardiovascular morbidity independently of plasma cholesterol lowering and in vitro studies support a direct anti-inflammatory action of these drugs. The aim of this study was to verify the in vivo effect of fluvastatin on complement-mediated acute peritoneal inflammation. The effect of oral treatment with fluvastatin was investigated in normo-cholesterolaemic rats that received intraperitoneal injection of either yeast-activated rat serum (Y-act RS) or lipopolysaccharide to induce peritoneal inflammation monitored by the number of PMN recruited in peritoneal fluid washes. In addition, vascular adherence and extravasation of leucocytes were evaluated by direct videomicroscopy examination on mesentery postcapillary venules topically exposed to Y-act RS. The number of PMN in the peritoneal washes of rats treated with fluvastatin was 38% lower than that of untreated animals (P < 0.05) 12 h after LPS injection, and was even lower (56%) in rats treated with Y-act RS already 8 h after injection (P < 0.02). Firm adhesion to endothelium and extravasation of leucocytes evaluated under direct videomicroscopy observation were significantly inhibited in fluvastatin treated rats (77% and 72%, respectively; P < 0.01), 120 min after treatment with Y-act RS. Our results demonstrate that fluvastatin inhibits in vivo complement-dependent acute peritoneal inflammation and suggest a role for statins in preventing the inflammatory flares usually associated with complement activation in chronic diseases, such as SLE or rheumatoid arthritis
Dynamical systems approach to space environment turbulence
No full textSpace plasmas are dominated by waves, instabilities and turbulence. Dynamical systems approach offers powerful mathematical and computational techniques to probe the origin and nature of space environment turbulence. Using the nonlinear dynamics tools such as the bifurcation diagram and Poincaré maps, we study the transition from order to chaos, from weak to strong chaos, and the destruction of a chaotic attractor. The characterization of the complex system dynamics of the space environment, such as the Alfvén turbulence, can improve the capability of monitoring Sun-Earth connections and prediction of space weather.A.C.-L. Chian, F.A. Borotto, E.L. Rempel, E.E.N. Macau, R.R. Rosa, F. Christianse
Attractor merging crisis in chaotic business cycles
No full textA numerical study is performed on a forced-oscillator model of nonlinear business cycles. An attractor merging crisis due to a global bifurcation is analyzed using the unstable periodic orbits and their associated stable and unstable manifolds. Characterization of crisis can improve our ability to forecast sudden major changes in economic systems.Abraham C.-L.Chian, Felix A. Borotto, Erico L. Rempel and Colin Rogershttp://www.elsevier.com/wps/find/journaldescription.cws_home/967/description#descriptio
Nonlinear dynamics and chaos in space plasmas
No full textThe theory and observation of nonlinear wave coupling phenomena in solar-system plasmas are reviewed. Rocket and satellite observations have provided evidence of nonlinear wave interactions in space plasmas, in particular, in relation to the generation and propagation of radio waves in solar corona, interplanetary medium and Earth's magnetosphere. These radio waves represent the electromagnetic signature of solar-terrestrial coupling and are useful for forecasting and monitoring of space weather. Nonlinear wave-wave coupling in plasmas can be modeled as a dynamical system of coupled oscillators involving one, two or higher-order wave triplets. For a three-wave dissipative system, the temporal transition from order to chaos may evolve via period doubling or intermittence. For a four-wave Hamiltonian system involving two coupled wave triplets, the spatiotemporal transition from order to chaos is analyzed using the concepts of stable and unstable homogeneous manifolds.Abraham Chian-Long Chian, José Ricardo Abalde, Félix Aldo Borotto, Sergio Roberto Lopes and Felipe Barbedo Rizzat
Fluvastatin treatment inhibits leucocyte adhesion and extravasation in models of complement-mediated acute inflammation.
No full textComplement activation plays a relevant role in the development of tissue damage under inflammatory conditions, and clinical and experimental observations emphasize its contribution to inflammatory vasculitides. Statins have recently been shown to reduce cardiovascular morbidity independently of plasma cholesterol lowering and in vitro studies support a direct anti-inflammatory action of these drugs. The aim of this study was to verify the in vivo effect of fluvastatin on complement-mediated acute peritoneal inflammation. The effect of oral treatment with fluvastatin was investigated in normo-cholesterolaemic rats that received intraperitoneal injection of either yeast-activated rat serum (Y-act RS) or lipopolysaccharide to induce peritoneal inflammation monitored by the number of PMN recruited in peritoneal fluid washes. In addition, vascular adherence and extravasation of leucocytes were evaluated by direct videomicroscopy examination on mesentery postcapillary venules topically exposed to Y-act RS. The number of PMN in the peritoneal washes of rats treated with fluvastatin was 38% lower than that of untreated animals (P < 0.05) 12 h after LPS injection, and was even lower (56%) in rats treated with Y-act RS already 8 h after injection (P < 0.02). Firm adhesion to endothelium and extravasation of leucocytes evaluated under direct videomicroscopy observation were significantly inhibited in fluvastatin treated rats (77% and 72%, respectively; P < 0.01), 120 min after treatment with Y-act RS. Our results demonstrate that fluvastatin inhibits in vivo complement-dependent acute peritoneal inflammation and suggest a role for statins in preventing the inflammatory flares usually associated with complement activation in chronic diseases, such as SLE or rheumatoid arthritis
Multi-spectral optical imaging of the spatiotemporal dynamics of ionospheric intermittent turbulence
No full textEquatorial plasma depletions have significant impact on radio wave propagation in the upper atmosphere, causing rapid fluctuations in the power of radio signals used in telecommunication and GPS navigation, thus playing a crucial role in space weather impacts. Complex structuring and self-organization of equatorial plasma depletions involving bifurcation, connection, disconnection and reconnection are the signatures of nonlinear evolution of interchange instability and secondary instabilities, responsible for the generation of coherent structures and turbulence in the ionosphere. The aims of this paper are three-fold: (1) to report the first optical imaging of reconnection of equatorial plasma depletions in the South Atlantic Magnetic Anomaly, (2) to investigate the optical imaging of equatorial ionospheric intermittent turbulence, and (3) to compare nonlinear characteristics of optical imaging of equatorial plasma depletions for two different altitudes at same times. We show that the degree of spatiotemporal complexity of ionospheric intermittent turbulence can be quantified by nonlinear studies of optical images, confirming the duality of amplitude-phase synchronization in multiscale interactions. By decomposing the analyses into North-South and East-West directions we show that the degree of non-Gaussianity, intermittency and multifractality is stronger in the North-South direction, confirming the anisotropic nature of the interchange instability. In particular, by using simultaneous observation of multi-spectral all-sky emissions from two different heights we show that the degree of non-Gaussianity and intermittency in the bottomside F-region ionosphere is stronger than the peak F-region ionosphere. Our results are confirmed by two sets of observations on the nights of 28 September 2002 and 9 November 2002.Abraham C.-L. Chian, José R. Abalde, Rodrigo A. Miranda, Felix A. Borotto, David L. Hysell, Erico L. Rempel, David Ruffol
“Stabilize the Unstable”: Treatment Pathophysiology in Bleeding Trauma Patients, from the Field to the ICU. State of the Art
No full textThe results of the Global Burden of Disease (GBD) study showed that, in 2019, 8% of deaths worldwide were trauma related [...
Chaos in magnetospheric radio emissions
No full textA three-wave model of auroral radio emissions near the electron plasma frequency was proposed by Chian et al. (1994) involving resonant interactions of Langmuir, whistler and Alfvén waves. Chaos can occur in the nonlinear evolution of this three-wave process in the magnetosphere. In particular, two types of intermittency, due to either local or global bifurcations, can be observed. We analyze the type-I Pomeau-Manneville intermittency, arising from a saddle-node bifurcation, and the crisis-induced intermittency, arising from an interior crisis associated with a global bifurcation. Examples of time series, power spectrum, phase-space trajectory for both types of intermittency are presented through computer simulations. The degree of chaoticity of this three-wave process is characterized by calculating the maximum Lyapunov exponent. We suggest that the intermit-tent phenomena discussed in this paper may be observed in the temporal signal of magnetospheric radio emissions
Chaotic temporal variability of magnetospheric radio emissions
No full textNonthermal magnetospheric radio emissions provide the radio signatures of solar-terrestrial connection and may be used for space weather forecasting. A three-wave model of auroral radio emissions at the fundamental plasma frequency was proposed by Chian et al. (1994) involving resonant interactions of Langmuir, whistler and Alfvén waves. Chaos can appear in the nonlinear evolution of this three-wave process in the magnetosphere. We discuss two types of intermittency in radio signals driven by temporal chaos: the type-I Pomeau-Manneville intermittency and the interior crisis-induced intermittency. Examples of time series for both types of intermittency are presented
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