Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2014
Review Historical ArticleCoagulation, flocculation, and denaturation: a century of research into protoplasmic theories of anesthesia.
Within two decades of the discovery of anesthesia, the physicochemical concept of colloid and the biological concept of protoplasm had emerged. Fusion of these concepts into a theoretical framework, which has been largely forgotten decades ago, promised to uncover fundamental biological truths and determined research into anesthetic mechanisms for a century after "Ether Day." Observations of optical changes in unstained tissue were condensed into a theory of anesthesia by coagulation of protoplasm in the 1870s. ⋯ This large body of work, swept aside during the decades of lipid membrane hegemony, has remained in obscurity even after proteins in excitable membranes became firmly established as mediators of the immediate anesthetic effects. This article is a reminder of the prolonged interdisciplinary research effort dedicated to "protoplasmic theories" at a time when attention is increasingly directed toward examining the nature of (un)consciousness well as noncanonical consequences of anesthetic exposure that are not easily accounted for within conventional pharmacological concepts.
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Anesthesia and analgesia · Aug 2014
The Role of Hippocampal Tau Protein Phosphorylation in Isoflurane-Induced Cognitive Dysfunction in Transgenic APP695 Mice.
Previous studies have shown that exposure to inhaled anesthetics can cause cognitive dysfunction, suggesting that general anesthesia might be a risk factor for the development of Alzheimer disease. However, the underlying mechanisms remain to be elucidated. In the present study, we tested our hypothesis that enhanced tau protein phosphorylation in hippocampus contributes to isoflurane-induced cognitive dysfunction in a mouse model of Alzheimer disease. ⋯ Isoflurane may induce cognitive dysfunction by enhancing phosphorylation of hippocampal tau protein at Ser262 site, and this effect is more significant in transgenic APP695 mice.
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Anesthesia and analgesia · Aug 2014
Prolonged Opioid Use After Knee Arthroscopy in Military Veterans.
Chronic postoperative pain occurs with an appreciable incidence after elective surgery. Known risk factors include perioperative pain and posttraumatic stress disorder (PTSD). Military veterans are a population at particular risk for PTSD and hence may be at increased risk for chronic pain after surgery. Our goal was to identify risk factors for chronic postoperative pain in young veterans after minor elective surgery, including the contribution of PTSD. ⋯ This single-center retrospective study suggests that the most important predictor of chronic postoperative pain is preoperative opioid use. For patients not taking opioids preoperatively, PTSD may increase the risk of prolonged postoperative opioid prescriptions and chronic postoperative pain, potentially related to patient age.
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Anesthesia and analgesia · Aug 2014
Mechanisms of Lidocaine's Action on Subtypes of Spinal Dorsal Horn Neurons Subject to the Diverse Roles of Na+ and K+ Channels in Action Potential Generation.
Superficial dorsal horn neurons of the spinal cord receive sensory information from Aδ and C fibers. According to their response to sustained depolarization, these cells can be divided into 3 groups: tonic (TFN), adapting (AFN), and single spike firing (SSN) neurons. During spinal and systemic administration of lidocaine, these neurons are exposed to different concentrations of the local anesthetic lidocaine. In this study, we explored its effect on the excitability of sensory neurons. ⋯ Lidocaine at low concentrations suppresses tonic firing neurons by interacting with voltage-gated potassium channels. The effects on adapting firing neurons can be explained by an interaction with voltage-gated sodium channels. In contrast, the firing pattern of SSN is not affected at the administered concentrations. This different sensitivity to low concentrations of sodium and particularly of potassium channel blockers might represent a novel approach for a differentiated blockade of different spinal dorsal horn neurons.
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Anesthesia and analgesia · Aug 2014
Comparative StudyNovel Use of Perineural Pregabalin Infusion for Analgesia in a Rat Neuropathic Pain Model.
The anticonvulsant drugs pregabalin and gabapentin are often used systemically to treat some forms of chronic neuropathic pain. However, many patients report side effects serious enough to cause discontinuation of the drug. Here we present evidence that pregabalin may block neuropathic pain when applied to the site of nerve injury in a rat neuropathic pain model. ⋯ Perineural pregabalin administration produced superior analgesia compared with that of systemic pregabalin in this neuropathic pain model. Perineural pregabalin treatment may provide a useful alternative to systemic pregabalin treatment for neuropathic pain.