Pain
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Existing microarray gene expression profiling studies of tonic/chronic pain were subjected to meta-analysis to identify genes found to be regulated by these pain states in multiple, independent experiments. Twenty studies published from 2002 to 2008 were identified, describing the statistically significant regulation of 2254 genes. Of those, a total of 79 genes were found to be statistically significant "hits" in 4 or more independent microarray experiments, corresponding to a conservative P<0.01 overall. ⋯ We independently confirmed the regulation of 43 of these genes in the rat-CCI-DRG condition; the genetic correlates in all other conditions were largely and, in some cases, strikingly, independent. However, a handful of genes were identified whose regulation bridged etiology, anatomical locus, and/or species. Most notable among these were Reg3b (regenerating islet-derived 3 beta; pancreatitis-associated protein) and Ccl2 (chemokine [C-C motif] ligand 2), which were significantly upregulated in every condition in the rat.
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Randomized Controlled Trial Multicenter Study
Efficacy of acupuncture for migraine prophylaxis: a single-blinded, double-dummy, randomized controlled trial.
Insufficient clinical trial data were available to prove the efficacy of acupuncture for migraine prophylaxis. A multicenter, double-dummy, single-blinded, randomized controlled clinical trial was conducted at the outpatient departments of acupuncture at 5 hospitals in China to evaluate the effectiveness of acupuncture. A total of 140 patients with migraine without aura were recruited and assigned randomly to 2 different groups: the acupuncture group treated with verum acupuncture plus placebo and the control group treated with sham acupuncture plus flunarizine. ⋯ The secondary outcome measures included the number of migraine days, visual analogue scale (VAS, 0 to 10 cm) for pain, as well as the physical and mental component summary scores of the 36-item short-form health survey (SF-36). The patients in the acupuncture group had better responder rates and fewer migraine days compared with the control group (P<.05), whereas there were no significant differences between the 2 groups in VAS scores and SF-36 physical and mental component summary scores (P>.05). The results suggested that acupuncture was more effective than flunarizine in decreasing days of migraine attacks, whereas no significantly differences were found between acupuncture and flunarizine in reduction of pain intensity and improvement of the quality of life.
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Comparative Study
A comparison of pain measures in newborn infants after cardiac surgery.
Accurate pain assessment tools to evaluate pain in critically ill neonates in the postoperative period are lacking. Therefore, we compared a number of potentially useful indices of pain in critically ill neonates following cardiac surgery. Eighty-one full-term infants were studied during the first 48 postoperative hours and the following indices were measured: heart rate, mean arterial blood pressure, heart-rate variability, urinary and plasma cortisol, and 4 composite pain measurement scales: Children's and Infants' Postoperative Pain Scale (CHIPPS), CRIES, COMFORT, and Premature Infant Pain Profile (PIPP). ⋯ The factor structure of the COMFORT score revealed that both behavioural and physiological variables account for a significant proportion of the variance (45% and 15%, respectively; P<0.001). Plasma concentrations of cortisol increased postoperatively but urinary cortisol excretion did not change significantly. Of the pain indices studied, the COMFORT score performed best, with both behavioural and physiological components providing significant contributions.
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Clinical studies have revealed that up to 92% of major depressed patients report pain complaints such as back or abdominal pain. Furthermore, patients suffering from depression exhibit increased superficial pain thresholds and decreased ischemic (deep) pain thresholds during experimental pain testing in comparison to healthy controls. Here, we aimed to investigate a putative role of Aδ- and C-fibre activation in altered pain perception in the disease. ⋯ Thus, Aδ-LEP might reflect the physiological correlate of the augmented superficial pain thresholds during depression. On the contrary, the C-fibre component mediates the facets of pain processing, outlasting the stimulation period, and has been shown to be exaggerated in chronic pain states. Therefore, the functional over-representation of the C-fibre component found in our study might be a possible link between depression and associated pain complaints.
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The purinergic P2X7 receptor is implicated in both neuropathic and inflammatory pain, and has been suggested as a possible target in pain treatment. However, the specific role of the P2X7 receptor in bone cancer pain is unknown. We demonstrated that BALB/cJ P2X7 receptor knockout (P2X7R KO) mice were susceptible to bone cancer pain and moreover had an earlier onset of pain-related behaviours compared with cancer-bearing, wild-type mice. ⋯ However, the recent discovery of a P2X7 receptor splice variant expressed in the knockout mice used for this study complicates the interpretation of the results. The P2X7 splice variant receptor was detected in the spinal cord but not in osteoclasts of the P2X7R KO mouse. Further experiments are needed to elucidate the exact role of the P2X7 receptors in bone cancer pain.