Pain
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Comparative Study
Stimulus-dependent specificity for annexin 1 inhibition of the inflammatory nociceptive response: the involvement of the receptor for formylated peptides.
In this study we investigated how the peptides derived from the glucocorticoid-inducible protein annexin 1 are able to alter the nociceptive threshold of mice. The effects of the annexin1 fragment 2-26 (Anxa1(2-26)) on nociceptive threshold were studied using both chemical (formalin test) and thermal (hot plate and tail flick test) nociceptive stimuli on mice. Subcutaneous administration of Anxa1(2-26) into the dorsal surface of the mouse's hind paw was able to selectively reduce formalin-induced nociceptive behavior in the last phase of the test. ⋯ We found that the formyl peptide receptor agonist formyl-MLF (fMLF) induced anti-nociceptive effects in the formalin test both after the peripheral and central administration. The formyl peptide receptor antagonist N-t-butoxycarbonyl-MLP did not alter the response to formalin, but it was able to block the anti-nociceptive effects of Anxa1(2-26,) Anxa1(2-12) and fMLF after peripheral or central administration. These results indicate that exogenously administered Anxa1 can peripherally and centrally inhibit the nociceptive transmission associated with inflammatory processes through a mechanism that involves formyl peptide receptors.
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Case Reports Comparative Study
Spinal cord lesion after long-term intrathecal clonidine and bupivacaine treatment for the management of intractable pain.
Long-term intrathecal drug administration using implanted pumps is increasingly used in the treatment of chronic refractory pain [Anderson and Burchiel 1999, Neurosurgery 44 (1999) 289; Krames 2002, Best Pract Res Clin Anaesthesiol 16 (2002) 619; Wallace 2002, Neurology 59 (2002) S18]. Extensive clinical experience over the last 15 years suggests that in selected cases the technique is safe, although infections, system malfunction and drug-related complications have been reported. In most cases, drug-related spinal cord injuries have resulted from the compression of a spinal inflammatory mass or abcess rather than from a direct neurotoxic effect. We report on a case of toxic spinal cord lesion occurring after more than 3 years of uneventful continuous infusion of a mixture of bupivacaine and clonidine.
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Comparative Study
Lessons learned from a multiple-dose post-operative analgesic trial.
Patients undergoing major surgery often require several days of post-operative analgesic management. However, little data are available on the course of post-operative pain during this period. Such data would be extremely helpful in planning treatment, formulating pain management guidelines, and determining how to construct multiple-dose post-operative analgesic clinical trials. ⋯ Only 9% of patients reported experiencing moderate-to-severe pain approximately 2 weeks later, at the end of the study. Describing pain as mild, moderate, or severe could be a simple, meaningful clinical trial outcome measure. Because most patients experience only mild pain 6 days after surgery, long-term clinical trials of post-operative pain control may be more efficient and cost-effective if they focus on the subset of patients with persistent moderate or severe pain.
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This experiment tested whether meaning influences the experience of pain. Thirty-one healthy students participated in a study on evaluations of various stimuli placed against the neck. ⋯ Confirming the hypothesis that tissue-damaging meaning influences the experience of pain, participants who were told that the bar was hot rated it as more painful than participants who were told that it was cold. Damage interpretations mediated the effect of information on pain intensity scores, which supported the theory that tissue-damage is a crucial aspect of meaning to influence the subjective intensity of pain.
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Comparative Study
Decreasing sympathetic sprouting in pathologic sensory ganglia: a new mechanism for treating neuropathic pain using lidocaine.
Lidocaine brings relief to those suffering from certain neuropathic pain syndromes in humans and in animal models. Evidence suggests that some neuropathic pain behaviors are closely associated with extensive sprouting of noradrenergic sympathetic fibers in the dorsal root ganglia (DRG). Using immunohistochemistry, we examined lidocaine's effects on abnormal sprouting of sympathetic fibers in two animal models: rats with unilateral spinal nerve ligation (SNL) and rats with complete sciatic nerve transection (CSNT). ⋯ Similar results were obtained after topical application of lidocaine to the nerve trunk to block abnormal discharges originating in the neuroma in CSNT rats. Results strongly suggest that sympathetic sprouting in pathologic DRG may be associated with abnormal spontaneous activity originating in the DRG or the injured axons (e.g. neuroma). This finding provides new insight into the mechanisms underlying sympathetic sprouting and increases our current understanding of the prolonged therapeutic effects of lidocaine on neuropathic pain syndromes.