Pain
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The transient receptor potential vanilloid subfamily member 2 (TRPV2) is a cation channel activated by temperatures above 52 degrees C. To analyze the contribution of TRPV2 to the development of inflammation-induced hyperalgesia, the expression of TRPV2 in primary sensory neurons was analyzed after intraplantar injection of complete Freund's adjuvant (CFA). Using specific antibodies, an increase in TRPV2-expressing neurons was identified after inflammation. ⋯ Intraplantar injection of nerve growth factor increased TRPV1 expression but not TRPV2, suggesting that induction of TRPV2 expression is driven by a mechanism distinct from that for TRPV1. Heat hyperalgesia assessment after chemical desensitization of TRPV1 by resiniferatoxin demonstrates a possible role for TRPV2 in inflammation at high temperatures (>56 degrees C). These results suggest that TRPV2 upregulation contributes to peripheral sensitization during inflammation and is responsible for pain hypersensitivity to noxious high temperature stimuli.
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The clinically available NMDA-receptor antagonist drug, amantadine, has been shown to result in morphine sparing effects in humans after surgery. However, no data are available to describe the exact form of interaction. The present study aims to profile the possible effects of amantadine (0, 12.5, 25 or 50 mgkg(-1) i.p.) pre-treatment on morphine (0, 0.63, 1.25, 2.5 or 5 mgkg(-1) s.c.) induced antinociception in rats. ⋯ No evidence was found to indicate that amantadine induced motor impairment at the doses potentiating morphine during the second phase of the formalin test. There was no evidence for a pharmacokinetic interaction between amantadine and morphine. Since, the second phase of the formalin test is dependent on activation of the NMDA receptor system it is concluded that an antagonistic activity of amantadine at the NMDA receptor most likely contributes to the synergistic interaction observed between amantadine and morphine in rats.
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Controlled Clinical Trial
The significant other version of the Pain Catastrophizing Scale (PCS-S): preliminary validation.
Researchers have hypothesized that pain catastrophizing has a social function. Although work has focused on the catastrophizing of individuals with chronic pain (ICPs), little is known about the pain catastrophizing of their significant others. The purpose of this study was to test the validity of a revised version of the original PCS [Sullivan MJL, Bishop S, Pivik J. ⋯ Spouse catastrophizing was related to ICP pain severity and interference as well as both spouses' depressive symptoms. In addition, ICPs were at a greater risk for psychological distress when both spouses had higher levels of catastrophizing. The PCS-S has the potential to be a useful and valid measure of pain catastrophizing in the significant others of ICPs.
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Controlled Clinical Trial
Does medication overuse headache represent a behavior of dependence?
Medication overuse is relatively common in patients with frequent headache. To explore the prevalence of patients who meet the criteria for substance dependence in Diagnostic and Statistical Manual of Mental Disorders, Edition IV (DSM-IV), and to identify variables of substance dependence among patients with chronic daily headache, we recruited consecutive patients with chronic daily headache at a headache clinic from November 1999 to June 2004. Each patient completed a headache intake form, a dependence questionnaire modified from DSM-IV, and the Hospital Anxiety and Depression Scale (HADS). ⋯ Patients who fulfilled DSM-IV criteria of dependence had higher numbers of physician appointments in the past year. Multivariate logistic regression analyses revealed that migraine headache, frequent physician consultation, intensity of headache, and presence of a higher anxiety score were significant independent variables for substance dependence. Among patients with chronic daily headache, pMOH was associated with behaviors of substance dependence.