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Publications (3)8.56 Total impact

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    ABSTRACT: Since the definition of systemic inflammatory response syndrome/sepsis was originally proposed, a large amount of new information has been generated showing a much more complex scenario of inflammatory and counterinflammatory responses during sepsis. Moreover, some fundamental mechanisms of sensing and destroying invading microorganisms have been uncovered, which include the discovery of TLR4 as the lipopolysaccharide (LPS) gene, implications of innate immune cells as drivers of the adaptive response to infection, and the modulation of multiple accessory molecules that stimulate or inhibit monocyte/macrophage and lymphocyte interactions. The complexity of the infection/injury-induced immune response could be better appreciated with the application of genomics and proteomics studies, and LPS was a useful tool in many of these studies. In this review, we discuss aspects of bacterial recognition and induced cellular activation during sepsis. Because of the relevance of endotoxin (LPS) research in the field, we focus on LPS and host interactions as a clue to understand microorganisms sensing and cell signaling, then we discuss how this response is modulated in septic patients.
    Shock (Augusta, Ga.) 07/2012; 38(3):227-42. · 2.87 Impact Factor
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    ABSTRACT: The pathogenetic mechanisms associated to the beneficial effects of mixed venous oxygen saturation (SvO(2))-guided resuscitation during sepsis are unclear. Our purpose was to evaluate the effects of an algorithm of SvO(2)-driven resuscitation including fluids, norepinephrine and dobutamine on hemodynamics, inflammatory response, and cardiovascular oxidative stress during a clinically resembling experimental model of septic shock. Eighteen anesthetized and catheterized pigs (35-45 kg) were submitted to peritonitis by fecal inoculation (0.75 g/kg). After hypotension, antibiotics were administered, and the animals were randomized to two groups: control (n = 9), with hemodynamic support aiming central venous pressure 8 to 12 mmHg, urinary output 0.5 mL/kg per hour, and mean arterial pressure greater than 65 mmHg; and SvO(2) (n = 9), with the goals above, plus SvO(2) greater than 65%. The interventions lasted 12 h, and lactated Ringer's and norepinephrine (both groups) and dobutamine (SvO(2) group) were administered. Inflammatory response was evaluated by plasma concentration of cytokines, neutrophil CD14 expression, oxidant generation, and apoptosis. Oxidative stress was evaluated by plasma and myocardial nitrate concentrations, myocardial and vascular NADP(H) oxidase activity, myocardial glutathione content, and nitrotyrosine expression. Mixed venous oxygen saturation-driven resuscitation was associated with improved systolic index, oxygen delivery, and diuresis. Sepsis induced in both groups a significant increase on IL-6 concentrations and plasma nitrate concentrations and a persistent decrease in neutrophil CD14 expression. Apoptosis rate and neutrophil oxidant generation were not different between groups. Treatment strategies did not significantly modify oxidative stress parameters. Thus, an approach aiming SvO(2) during sepsis improves hemodynamics, without any significant effect on inflammatory response and oxidative stress. The beneficial effects associated with this strategy may be related to other mechanisms.
    Shock (Augusta, Ga.) 09/2011; 36(6):604-12. · 2.87 Impact Factor
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    ABSTRACT: Pre-exposure to low doses of LPS induces resistance to a lethal challenge, a phenomenon known as endotoxin tolerance. In this study, tolerance was induced in human PBMC by culturing cells with 1 ng/mL LPS for 48 h. Cells were subsequently challenged with 100 ng/mL LPS for 2, 6 and 24 h, and the expression of 84 genes encoding proteins involved in the TLR signaling pathway was evaluated at each time point by PCR array. LPS pretreatment did not modulate the expression of TLR4 and CD14 on the surface of monocytes. A gene was defined as tolerized when LPS pretreatment reversed the effect of LPS challenge on the expression of the gene or as non-tolerized when LPS pretreatment did not reverse the effects of LPS challenge. We observed impaired signal transduction through the NF-κB, JNK, ERK and TRIF pathways, whereas expression of p38 pathway-related genes was preserved in LPS-tolerant cells. These results show a distinct regulation of the TLR pathway cascades during tolerance; this may account for the differential gene expression of some inflammatory mediators, such as up-regulation of IL-10 and COX2 as well as down-regulation of TNF-α and IL-12. Depending on the effect of LPS-induced gene up-regulation or down-regulation, tolerance, as a reversion of such LPS effects, may result in repression or induction of gene expression.
    Immunobiology 03/2011; 216(3):285-95. · 2.81 Impact Factor