Pain
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The effects of nitrous oxide (N2O) are thought to be mediated by several pharmacological pathways at different levels of the central nervous system. Here, we focus on excitatory glutamatergic transmission in the superficial dorsal horn of the spinal cord with respect to its importance for the nociceptive processing. The effects of 50% N2O on electrically evoked and spontaneous excitatory glutamatergic transmission and on the response to exogenous administration of N-methyl-d-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid (AMPA) receptor agonists were examined in lamina II neurons of adult rat spinal cord slices using the whole-cell patch-clamp technique. ⋯ Moreover N2O changed the distribution of miniature EPSC amplitude, but not frequency distribution in most neurons. N2O inhibits glutamatergic transmission in the superficial dorsal horn by modulating the NMDA- and AMPA-receptors. Our findings raise the possibility that the antinociceptive effect of N2O may be directly mediated at the level of the spinal cord.
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Comparative Study
The inventory of parent/caregiver responses to the children's pain experience (IRPEDNA): development and preliminary validation.
This paper describes the development and preliminary validation of a self-administered instrument designed to measure parents/caregivers' responses to children's pain episodes. For empirical validation purposes, a 60-item inventory was answered by 401 adults whose children's ages ranged from 6 to 16 years (mean=10.44, and SD=2.25 years). Factor structure and item analyses led to a 37 item inventory with three interrelated scales, namely: solicitousness (n=15 items), discouragement (n=10 items), and promotion of well-behaviors and coping (n=12 items). The three scales had good internal consistency, with coefficient alphas of 0.87, 0.83 and 0.87, respectively; they also showed good criterion-related validity.
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Comparative Study
Serotonin (5-HT) excites rat masticatory muscle afferent fibers through activation of peripheral 5-HT3 receptors.
In the present study, we combined immunohistochemical experiments with in vivo single unit recordings to examine whether 5-HT(3) receptors are expressed by masticatory (masseter and temporalis) sensory ganglion neurons and to investigate the effects of intramuscular injection of 5-HT on the excitability and mechanical threshold of rat masticatory muscle afferent fibers. The expression of 5-HT(3) receptors by masticatory ganglion neurons was examined using immunohistochemical techniques. In vivo extracellular single unit recording techniques were used to assess changes in the excitability of individual masticatory muscle afferent fibers. ⋯ Unexpectedly, a significant concentration-related decrease in median blood pressure in response to 5-HT injection was found. This 5-HT-induced decrease in blood pressure was not antagonized by tropisetron or mimicked by 2-methyl-5-HT, indicating that the drop in blood pressure was not 5-HT(3) receptor-mediated. The present results indicate that 5-HT excites slowly conducting masticatory muscle afferent fibers through activation of peripheral 5-HT(3) receptors, and suggest that similar mechanisms may contribute to 5-HT-evoked muscle pain in human subjects.
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Randomized Controlled Trial Comparative Study
A randomized controlled trial of perioperative administration of pregabalin for pain after laparoscopic hysterectomy.
Pregabalin has anticonvulsant, antihyperalgesic, and anxiolytic properties. In this study we evaluated the control of pain after perioperative administration of pregabalin 300 or 600 mg, compared with diazepam 10mg. Altogether 91 women scheduled for laparoscopic hysterectomy were randomized to receive diazepam 10mg (D10), pregabalin 150 mg (P300) or 300 mg (P600) for premedication, and the dose was repeated after 12h, except for the D10 group, in which the patients received placebo. ⋯ The total dose of oxycodone (0-24h after surgery) was smaller in the P600 group than in the D10 group (0.34 vs. 0.45 mg kg(-1); P=0.046). The incidence of dizziness (70% vs. 35%; P=0.012), blurred vision (63% vs. 14%; P=0.002) and headache (31% vs. 7%; P=0.041) were higher in the P600 group than in the D10 group. In conclusion, perioperative administration of pregabalin 600 mg decreases oxycodone consumption compared with diazepam 10mg, but is associated with an increased incidence of adverse effects.
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Comparative Study
The Fear of Pain Questionnaire-Short Form (FPQ-SF): factorial validity and psychometric properties.
McNeil and Rainwater's Fear of Pain Questionnaire III (FPQ-III, 1998) is an empirically derived self-report inventory that assesses fear of three broad categories of pain: Severe, Minor, and Medical Pain. Previous exploratory and confirmatory factor analyses suggest that the original 3-factor model of the FPQ-III has a poor fit [Osman A, Breitenstein JL, Barrios FX, Gutierrez PM, Kopper BA. The Fear of Pain Questionnaire-III: further reliability and validity with nonclinical samples. ⋯ This model comprised 20-items distributed on factors representing Severe, Minor, Injection, and Dental Pain. The total scale and subscale scores based on the 4-factor model had good internal consistency, and preliminary support for construct validity was obtained. Use of this short version of the measure--the FPQ-Short Form--is discussed and directions for future research outlined.