Pain
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The objective of this study was to examine the influence of variations in contextual features of a physically demanding lifting task on the judgments of others' pain. Healthy undergraduates (n=98) were asked to estimate the pain experience of chronic pain patients who were filmed while lifting canisters at different distances from their body. Of interest was whether contextual information (i.e., lifting posture) contributed to pain estimates beyond the variance accounted for by pain behavior. ⋯ Results also indicated that observers' level of catastrophizing was associated with more accurate pain estimates. The results of a regression analysis further showed that observers' level of catastrophizing contributed to the prediction of the accuracy of pain estimates over and above the variance accounted for by the utilisation of contextual features. Discussion addresses the processes that might underlie the utilisation of contextual features of a pain-eliciting task when estimating others' pain.
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The Child Activity Limitations Interview (CALI) is a measure designed to assess functional impairment due to chronic pain in school-age children. In this study, we present a self-report questionnaire version of the CALI (the CALI-21) that extends the original interview measure. The purpose of this study was to provide internal consistency, cross-informant reliability and construct validity of the CALI-21 on a clinical sample of children and adolescents with chronic pain conditions. ⋯ The CALI-21 showed good internal consistency, high cross-informant reliability, and demonstrated construct validity. The CALI-21 provides increased flexibility via the questionnaire format in the assessment of pain-related activity limitations in children. Factor analysis extends information about specific types of activity limitations experienced by children.
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Palmitoylethanolamide (PEA) is an endogenous lipid that is thought to be involved in endogenous protective mechanisms activated as a result of stimulation of inflammatory response. In spite of the well demonstrated anti-inflammatory properties of PEA, its involvement in controlling pain pathways still remains poorly characterized. On this basis, we tested the efficacy of PEA in vivo against a peculiar persistent pain, such as neuropathic one. ⋯ The results indicated that CB(1), PPARgamma and TRPV1 receptors mediated the antinociception induced by PEA, suggesting that the most likely mechanism might be the so-called "entourage effect" due to the PEA-induced inhibition of the enzyme catalyzing the endocannabinoid anandamide (AEA) degradation that leads to an enhancement of its tissue levels thus increasing its analgesic action. In addition, the hypothesis that PEA might act through the modulation of local mast cells degranulation is sustained by our findings showing that PEA significantly reduced the production of many mediators such as TNFalpha and neurotrophic factors, like NGF. The findings presented here, in addition to prove the beneficial effects of PEA in chronic pain, identify new potential targets for analgesic medicine.
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The standard rodent model of itch uses scratching with the hind limb as a behavioral response to pruritic stimuli applied to the nape of the neck. The assumption is that scratching is an indicator of the sensation of itch. But because only one type of site-directed behavior is available, one cannot be certain that scratching is not a response to nociceptive or other qualities of sensations in addition to, or instead of, itch. ⋯ In contrast, when the same chemicals were injected into the cheek of the mouse, there were two site-directed behaviors: histamine again elicited scratching with the hind limb, but capsaicin evoked wiping with the forelimb. We conclude that the "cheek model of itch" in the mouse provides a behavioral differentiation of chemicals that elicit predominantly itch in humans from those that evoke nociceptive sensations. That is, the model provides a behavioral differentiation between itch and pain in the mouse.
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The origins of chronic muscle pain development and maintenance are debated regarding the relative contributions of peripheral nociception and central pain processing. Bradykinin (BKN) and kallidin (KAL) have been suggested to be algesic kinins involved in muscle pain. This in vivo study investigates whether there were significant differences in interstitial muscle concentrations of BKN and KAL between chronic work-related trapezius myalgia (TM), chronic whiplash associated disorders (WAD), and healthy controls (CON). ⋯ In chronic pain, positive correlations existed between the two kinins and the difference in pain intensity between recovery and baseline. In this in vivo study of two groups of patients with chronic pain clinically involving the trapezius muscle, we found alterations - most prominent in TM - in the interstitial concentrations of BKN and KAL. The results indicated that the two kinins were involved in aspects of hyperalgesia.