Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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Hemorrhagic shock (HS) is associated with the disruption of endothelial cell barrier leading to vascular hyperpermeability. Previous studies from our laboratory implicate reactive oxygen species (ROS) and the intrinsic apoptotic signaling cascades as mediators of vascular hyperpermeability after HS. Here we report the protective effects of alpha-lipoic acid, a natural antioxidant with antiapoptotic properties, against vascular hyperpermeability after HS. ⋯ Hemorrhagic shock resulted in vascular hyperpermeability and mitochondrial ROS formation. The activation of mitochondrial intrinsic apoptotic signaling pathway was evidenced from mitochondrial depolarization, an increase in cytochrome c release, and activation of caspase 3. alpha-Lipoic acid (100 mg/kg) given before the shock period attenuated vascular hyperpermeability, mitochondrial ROS formation, mitochondrial depolarization, cytochrome c release, and activation of caspase 3 (P < 0.05). Together, these results demonstrate that alpha-lipoic acid provides protection against vascular hyperpermeability by modulating the mitochondrial "intrinsic" apoptotic signaling.
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Alveolar type 2 (AT-2) cell apoptosis is an important mechanism during lung inflammation, lung injury, and regeneration. Blunt chest trauma has been shown to activate inflammatory cells such as alveolar macrophages (AMs) or neutrophils (polymorphonuclear granulocytes [PMNs]), resulting in an inflammatory response. The present study was performed to determine the capacity of different components/cells of the alveolar compartment (AMs, PMNs, or bronchoalveolar lavage [BAL] fluids) to induce apoptosis in AT-2 cells following blunt chest trauma. ⋯ In contrast, no apoptosis was induced in AT-2 cells incubated with supernatants of activated PMNs or BAL fluids of traumatized animals. In summary, blunt chest trauma induced apoptosis in AT-2 cells, possibly involving the extrinsic death receptor pathway. Furthermore, mediators released by AMs appeared to be involved in the induction of AT-2 cell apoptosis.
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Hemodynamic support of patients with septic shock is often complicated by a tachyphylaxis against exogenous catecholamines. Because an increase in somatotropic hormones may play a pivotal role in the regulation of the inflammatory response to endotoxin, intravenous supplementation of the neuroendocrine hormone somatostatin (SOMA) may attenuate hemodynamic dysfunction resulting from endotoxemia. The objective of the present study was to assess the short-term effects of SOMA alone and in combination with norepinephrine (NE) on cardiopulmonary hemodynamics, global oxygen transport, plasma nitrate/nitrite levels, and intestinal integrity compared with single NE therapy in ovine endotoxemia. ⋯ In conclusion, short-term treatment with SOMA failed to attenuate cardiocirculatory shock resulting from endotoxemia and did not improve vasopressor response to NE. In addition, combined SOMA and NE therapy resulted in intestinal injury. Therefore, SOMA does not seem to represent a therapeutic option to treat arterial hypotension resulting from sepsis and systemic inflammatory response syndrome.
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Editorial Review
Arterial pulse pressure variation predicting fluid responsiveness in critically ill patients.
In critically ill patients, it is important to predict which patients will have their systemic blood flow increased in response to volume expansion to avoid undesired hypovolemia and fluid overloading. Static parameters such as the central venous pressure, the pulmonary arterial occlusion pressure, and the left ventricular end-diastolic dimension cannot accurately discriminate between responders and nonresponders to a fluid challenge. In this regard, respiratory-induced changes in arterial pulse pressure have been demonstrated to accurately predict preload responsiveness in mechanically ventilated patients. Some experimental and clinical studies confirm the usefulness of arterial pulse pressure as a useful tool to guide fluid therapy in critically ill patients.