Pain
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Positron emission tomography (PET) imaging of spinal cord in monkeys with a cholinergic tracer demonstrates increased spinal cholinergic activity in response to an analgesic dose of morphine, and this PET result correlates with measurement of acetylcholine spillover into spinal cord extracellular space induced by morphine, as measured by microdialysis. Previous studies in rats, mice, and sheep demonstrate activation of spinal cholinergic neurons by systemic opioid administration, and participation of this cholinergic activity in opioid-induced analgesia. Testing the relevance of this observation in humans has been limited to measurement of acetylcholine spillover into lumbar cerebrospinal fluid. ⋯ The one animal which did not show increased spinal cholinergic activity by PET from this dose of morphine also did not show increased acetylcholine from this morphine dose in the microdialysis experiment. These data confirm the ability to use PET to image spinal cholinergic terminals in the monkey spinal cord and suggest that acute changes in cholinergic activity can be imaged with this non-invasive technique. Following preclinical screening, PET scanning with [(18)F]FBT may be useful to investigate mechanisms of analgesic action in normal humans and in those with pain.
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The present research addressed the relation between catastrophizing, depression and response expectancies in anticipation of an experimental pain procedure. One hundred and twenty undergraduates (48 men, 72 women) participated in exchange for course credit. Prior to immersing one arm in a container of ice water, participants were asked to complete measures of catastrophizing and depression, and to estimate the degree of pain and emotional distress they expected to experience. ⋯ Catastrophizing, but not depression, was associated with a tendency to underestimate pain and emotional distress. The implications of these findings for the conceptual distinctiveness of catastrophizing and depression are discussed. Discussion also examines the potential implications of the present findings for pain management interventions.
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While psychosocial factors are known to influence treatment outcomes in low back pain patients, relatively little is known about how they may influence work injury management of low back pain. This study examined medical and psychosocial factors associated with work injury management decisions relative to patients with occupational low back pain. A retrospective review of 132 patients who had settled their injury claims showed that two psychosocial factors, ethnicity and litigation status, were associated with work injury management. ⋯ Having evidence of a specific lesion and legal representation were also associated with claimants' final disability ratings. Results are discussed in terms of a model of social judgment in which properties of the judge, target, and context influence judgments. Implications for work injury management and disability determination, as well as future research are discussed.