Pain
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This study examined the relationship between catastrophizing and patient-perceived partner responses to pain behaviors. The Catastrophizing subscale of the Cognitive Coping Strategy Inventory and the West Haven-Yale Multidimensional Pain Inventory were completed by 62 adult chronic pain patients. Consistent with past research, catastrophizing and patient-perceived solicitous partner behaviors were positively correlated with negative pain outcomes. ⋯ However, catastrophizing was not related to perceived solicitous partner behavior in this study. Rather, catastrophizing was associated with perceived punishing partner responses. Implications are that catastrophizing and perceived solicitous partner behaviors are independently associated with pain and that catastrophizing may not be reinforced by empathy from significant others.
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While a variety of cultural, psychological and physiological factors contribute to variability in both clinical and experimental contexts, the role of genetic factors in human pain sensitivity is increasingly recognized as an important element. This study was performed to evaluate genetic influences on variability in human pain sensitivity associated with gender, ethnicity and temperament. Pain sensitivity in response to experimental painful thermal and cold stimuli was measured with visual analogue scale ratings and temperament dimensions of personality were evaluated. ⋯ Female European Americans with the TRPV1 Val(585) Val allele and males with low harm avoidance showed longer cold withdrawal times based on the classification and regression tree (CART) analysis. CART identified gender, an OPRD1 polymorphism and temperament dimensions of personality as the primary determinants of heat pain sensitivity at 49 degrees C. Our observations demonstrate that gender, ethnicity and temperament contribute to individual variation in thermal and cold pain sensitivity by interactions with TRPV1 and OPRD1 single nucleotide polymorphisms.
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In the peripheral nervous system, N-methyl-D-aspartate receptors (NMDAR) expressed on the central and peripheral terminals of primary afferent neurons are involved in nociception. We used single cell imaging of intracellular calcium concentration ([Ca2+]i) and patch clamp techniques to characterize the functional properties of NMDARs on adult rat dorsal root ganglia (DRG) neurons in primary culture and selectively on those innervating the distal colon. In Mg2+-free extracellular solution, rapid perfusion of DRG neurons with 250 microM NMDA and 10 microM glycine caused a significant increase in [Ca2+]i, and elicited inward currents in whole cell patch clamp recordings when the holding potential was -60 mV. ⋯ There was no evidence of multiple binding sites for ifenprodil. There was no significant difference in the NMDAR current density on DRG neurons that had innervated the colon, nor was there a difference in the EC50 for ifenprodil. These results demonstrate that functional NMDARs expressed by DRG neurons innervating both somatic and visceral tissues of adult rats are composed predominantly of NR2B subunits.
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Diabetes can induce a bewildering list of sensory changes, including alteration in pain sensitivity. Painful diabetic neuropathy is refractory to most common analgesics. This study examined the effect of a p38alpha MAPK inhibitor, SD-282, on mechanical allodynia, thermal hyperalgesia, and formalin-evoked nociception in streptozotocin-induced diabetic rats. ⋯ Repeated administration of 45 mg/kg SD-282 attenuated flinching behaviors during the quiescent period and the second phase of the formalin response in diabetic rats. Acute and repeated administration of 15 or 45 mg/kg SD-282 had no effect on mechanical, thermal or formalin responses in age-matched control rats. These results indicate a potential therapeutic value of p38alpha MAPK inhibitors in the treatment of aberrant pain sensitivity produced by diabetes.
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Randomized Controlled Trial Comparative Study Clinical Trial
A double-blind placebo-controlled comparison of tramadol/acetaminophen and tramadol in patients with postoperative dental pain.
The objective of this study was to compare the analgesic efficacy of tramadol/acetaminophen (APAP) (total dose 75 mg/650 mg) and tramadol (total dose 100 mg) for the control of pain after oral surgery. A total of 456 patients with moderate-to-severe pain within 5 h after extraction of two or more third molars were randomized to receive two identical encapsulated tablets containing tramadol/APAP 37.5 mg/325 mg, tramadol 50 mg, or placebo. ⋯ The most common adverse events with active treatment were nausea, dizziness, and vomiting; these events occurred more frequently in the tramadol group than in the tramadol/APAP group. This study established the superiority of tramadol/APAP 75 mg/650 mg over tramadol 100 mg in the treatment of acute pain following oral surgery.