The journal of pain : official journal of the American Pain Society
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Neuropeptides released from axons of primary afferent nociceptive neurons are the key elements for the incidence of neurogenic inflammation and their release is associated with dorsal root reflexes (DRRs). However, whether the release is due to the triggering of DRRs and plays a role in inflammation-induced pain still remain to be determined. The present study assessed the role of calcitonin gene-related peptide (CGRP) in sensitization of primary afferent nociceptors induced by activation of transient receptor potential vanilloid-1 (TRPV(1)) after intradermal injection of capsaicin and determined if this release is due to activation of primary afferent neurons antidromically by triggering of DRRs. Under dorsal root intact conditions, primary afferent nociceptive fibers recorded in anesthetized rats could be sensitized by capsaicin injection, as shown by an increase in afferent responses and lowering of the response threshold to mechanical stimuli. After DRRs were removed by dorsal rhizotomy, the capsaicin-evoked sensitization was significantly reduced. In dorsal root intact rats, peripheral pretreatment with a CGRP receptor antagonist could dose-dependently reduce the capsaicin-induced sensitization. Peripheral post-treatment with CGRP could dose-dependently restore the capsaicin-induced sensitization under dorsal rhizotomized conditions. Capsaicin injection evoked increases in numbers of single and double labeled TRPV(1) and CGRP neurons in ipsilateral dorsal root ganglia (DRG). After dorsal rhizotomy, these evoked expressions were significantly inhibited. ⋯ These data indicate that the DRR-mediated neurogenic inflammation enhances sensitization of primary afferent nociceptors induced by capsaicin injection. The underlying mechanism involves antidromic activation of DRG neurons via upregulation of TRPV(1) receptors whereby CGRP is released peripherally.
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In recent years, the National Institutes of Health (NIH) has experienced unprecedented reductions in its customary annual budget increases. Consequently, researchers, health care policy planners and others have a pressing need for accurate information on NIH funding patterns. We created a unique and objective system for compiling, classifying, and analyzing data on NIH grant awards and funding for research on pain, nausea, and dyspnea using naïve observers, cross-validation by multiple raters, and face validation by experts. We present results of our method and analyses for the period from 2003 to 2007. Following a 12% increase from 2003 to 2004, funding for pain research fell by 9.4% per year on average over the next 3 years. The percent of the total NIH budget going to support pain research increased to 0.78% in 2004 but fell to 0.61% in 2007. A piecewise regression model confirmed the declining trend represented a significant fit to the data (R(2)=0.98, p=0.024). Separate breakdowns by Institutes showed similar patterns. Analyses of nausea and dyspnea research support revealed small but steady increases over the same period. Declining support for pain research disproportionate to decreases in the NIH budget signals a need for measures to promote funding for meritorious applications. ⋯ Results of 5 year trends in numbers of grants and funding for research in pain, nausea, and dyspnea by the NIH show overall declines for pain but slight increases for nausea and dyspnea. Declining support for pain research that exceeds the reductions in the total NIH budget signals a need for measures to increase pain research funding.
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Multicenter Study
Validating PRISM (Pictorial Representation of Illness and Self Measure) as a measure of suffering in chronic non-cancer pain patients.
The Pictorial Representation of Illness and Self Measure (PRISM) is a recently developed tool designed to measure the burden of suffering due to illness in a variety of patient populations. The purpose of the current study was to validate PRISM as a measure of suffering in patients with chronic non-cancer pain. Patients (n = 138) were recruited from 2 hospital pain clinics, where they were participating in a 10-week, mindfulness-based chronic pain management course and during which they completed validated questionnaires to assess their outcomes. Convergent validity was assessed by correlating their PRISM scores with scores on the Short-Form 36v2 quality of life instrument, the Pain Catastrophizing Scale, and the 0 to 10 Numeric Pain Scale. Content validity and test-retest reliability were assessed, and a factor analysis performed to identify relationships among the PRISM domains. PRISM was found to have good reliability and was significantly correlated with many of the subdomains of the other questionnaires. Qualitative data (n = 26) revealed that PRISM was well understood and that there was consistency in interpreting the task. Our data suggest that the PRISM task measures constructs relating to quality of life, pain catastrophizing, and pain intensity and probably measures suffering in patients with chronic non-cancer pain, providing a novel and quick tool for clinicians. ⋯ This study demonstrates the reliability and validity of the PRISM task for measuring the burden of pain in a population of chronic pain sufferers. Clinicians in the field of chronic pain management may find PRISM useful for monitoring the impact of pain management strategies on pain perception and the psychosocial variables that influence suffering.