Anesthesiology
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Experimental and clinical studies have shown reduction in intrapulmonary shunt with improved oxygenation by spontaneous breathing with airway pressure release ventilation (APRV) in acute lung injury. The mechanisms of these findings are not clear. The authors hypothesized that spontaneous breathing results in better aeration of lung tissue and that improvement in oxygenation can be explained by these changes. This hypothesis was studied in a porcine model of oleic acid-induced lung injury. ⋯ The results support the hypothesis that spontaneous breathing during APRV improves oxygenation mainly by recruitment of nonaerated lung and improved aeration of the lungs.
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Developmental differences in short- and long-term responses to pain, especially surgical pain, have received minimal attention. The purpose of the present study was to examine postoperative responses in rats of developmental ages paralleling the infant to young adult human. ⋯ The more rapid recovery of the younger animals from the mechanical allodynia but not thermal hypersensitivity after surgery suggests the presence of developmental differences in modulation of A-fiber sensitization after surgery. However, the lack of age difference in recovery of thermal hypersensitivity after surgery suggests that sensitization of C-fiber input has a similar time course of resolution of pain over the ages studied in this model. The neural bases for these developmental differences are under study and may lead to a better understanding of pain during development and altered approaches to treatment of postoperative pain in neonates and infants.
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During cerebral ischemia, excess of glutamate release and dysfunction of its high affinity transport induce an accumulation of extracellular glutamate, which plays an important role in neuronal death. The authors studied the relationship among propofol neuroprotection, glutamate extracellular concentrations, and glutamate transporter activity in a model of ischemic cortical cell cultures. ⋯ Propofol showed a neuroprotective effect in this in vitro model of OGD, which was apparently mediated by a GLT1-independent restoration of the glutamate uptake impaired during the injury.
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The authors recently demonstrated that administration of the melanocortin-4 receptor antagonist SHU9119 decreased neuropathic pain symptoms in rats with a sciatic chronic constriction injury. The authors hypothesised that there is a balance between tonic pronociceptive effects of the spinal melanocortin system and tonic antinociceptive effects of the spinal opioid system. Therefore, they investigated a possible interaction between these two systems and tested whether opioid effectiveness could be increased through modulation of the spinal melanocortin system activity. ⋯ Together, these data confirm that there is an interaction between the spinal melanocortin and opioid systems and that combined treatment with melanocortin-4 receptor antagonists and opioids might possibly contribute to the treatment of neuropathic pain.