Pain
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Fatty acid ethanolamides (FAEs), which include palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), are endogenous agonists of peroxisome proliferator-activated receptor-α (PPAR-α) and important regulators of the inflammatory response. They are degraded in macrophages by the lysosomal cysteine amidase, N-acylethanolamine acid amidase (NAAA). Previous studies have shown that pharmacological inhibition of NAAA activity suppresses macrophage activation in vitro and causes marked anti-inflammatory effects in vivo, which is suggestive of a role for NAAA in the control of inflammation. ⋯ ARN077 reversed these biochemical effects. The results identify ARN077 as a potent inhibitor of intracellular NAAA activity, which is active in vivo by topical administration. The findings further suggest that NAAA regulates peripheral pain initiation by interrupting endogenous FAE signaling at PPAR-α.
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Following nociceptive heat or laser stimulation, an early contralateral and later vertex potential can be recorded. Although more indicative of the nociceptive input, the acquisition of the contralateral N1 after contact heat stimulation (contact heat-evoked potentials [CHEPs]) remains difficult. An advantage of contact heat is that the baseline skin temperature preceding peak stimulation can be controlled. ⋯ Based on standard averaging, N2/P2 amplitudes were also significantly increased with and without an accompanying change in the rating of perceived pain when the baseline temperature was increased (P<.05). In contrast, automated single-trial averaging revealed no significant difference in N2 amplitude when the baseline temperature was increased to 42°C and the peak temperature reduced. These findings suggest that 2 mechanisms underlie the improved acquisition of CHEPs: increased synchronization of afferent volley, yielding larger-amplitude evoked potentials in response to the same rating of intensity; and reduced inter-trial variability.
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Randomized Controlled Trial
Impact of being primed with social deception upon observer responses to others' pain.
This study examined whether priming with social deception affects responses (pain estimates, self-reported sympathy, inclination to help) towards others' pain. We further explored whether the priming effect is mediated by the valence of the patients (positive/negative), as indicated by the participants. First, participants (N=55) took part in an 'independent' delayed memory study in which they read either a neutral text about the use of the health care system (neutral condition) or a text about its misuse (social deception condition). ⋯ Results revealed no direct effect of priming with social deception. However, priming with social deception was related to less positive rating of the valence of the patients, that were related to lower ratings on pain and sympathy, and to larger discrepancies between the ratings of the patients and the observers. The results indicate that observers attribute less pain, feel less sympathy, and take patients' self-reported pain intensity less into account when the patients are evaluated less positively, which is likely to occur when a cognitive scheme of social deception is primed.
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Patient-reported outcome measures are being developed for more relevant assessments of pain management. The patient acceptable symptom state (PASS) ("feeling well") and the minimal clinically important improvement (MCII) ("feeling better") have been determined in clinical trials, but not in daily pain management. We carried out a national multicenter cohort study of patients over the age of 50years with painful knee osteoarthritis (KOA) or hip osteoarthritis (HOA) who had visited their general practitioner and required treatment for more than 7days. ⋯ This improvement is smaller than that recorded in randomized controlled trials, and was the same for both sites, both at rest and on movement. In conclusion, patient-reported outcome values in daily practice differ from those in clinical trials, and their determinant factors may depend on the site of osteoarthritis. Assessments of the treatment of painful osteoarthritis should be adapted to the characteristics and daily life of the patient, to personalize patient management.