European journal of pain : EJP
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The biobehavioural pain reactivity and recovery of preterm infants in the neonatal period may reflect the capacity of the central nervous system to regulate neurobiological development. ⋯ The infants exhibiting a high neonatal clinical risk showed high arousal during the puncture procedure and higher physiological reactivity in the recovery phase.
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Endogenous cannabinoids and peripheral cannabinoid CB2 receptors (CB2Rs) are involved in the antinociceptive effect of electroacupuncture (EA) on inflammatory pain. However, it is not clear how CB2R activation contributes to the antinociceptive effect of EA. The major proinflammatory cytokines, such as tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6, are involved in inflammatory pain. ⋯ Furthermore, EA or AM1241 treatment significantly decreased the mRNA and protein levels of IL-1β, IL-6 and TNF-α in inflamed skin tissues. In addition, pretreatment with AM630 significantly reversed the inhibitory effect of EA on these cytokine levels in inflamed skin tissues. Our results suggest that EA reduces inflammatory pain and proinflammatory cytokines in inflamed skin tissues through activation of CB2Rs.
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Fixed-dose combination analgesics are used widely, and available both on prescription and over-the-counter. Combination drugs should provide more analgesia than with any single drug in the combination, but there is no evidence in humans about whether oral combinations have just additive effects, or are synergistic or even subadditive. We suggest that the measured result for the combination would be the summation of the absolute benefit increase (effect of active drug minus effect of placebo) of each component of a combination if effects were (merely) additive, and greater than the sum of the absolute benefits if they were synergistic. ⋯ Results showed that expected numbers needed to treat (NNT) for additive effects were generally within the 95% confidence interval of measured NNTs. This was true for combinations of paracetamol plus ibuprofen and paracetamol plus opioids in acute pain, and naproxen plus sumatriptan in migraine, but not where efficacy was very low or very high, nor combinations of paracetamol plus dextropropoxyphene. There was no evidence of synergy, defined as supra-additive effects.
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The fundamental aspects of bone associated pain in humans are not fully understood. In this study pressure pain applied to the tibia bone was investigated experimentally in humans and by means of computer simulations. In humans, the pressure pain sensitivity and the relation between tissue indentation and pressure intensity were recorded by a computer-controlled pressure algometer with two different probe sizes (0.03 cm(2) and 1.0 cm(2)). ⋯ For both probes the strain peaked in adipose tissue at 0.29, and in the bone interface it was reduced by 3% (0.03 cm(2)) and 15% (1.0 cm(2)), respectively. For both probes the stress peaked at 235 kPa in skin layer, and in the deeper layers it was reduced to 50 kPa. Mechanosensitive nociceptors innervating the periosteum are ideally placed to mediate pain evoked by pressure stimulation on the tibia bone and small diameter probes may be optimal for assessing bone associated pain sensitivity.