Pain
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Bradykinin is a peptide implicated in inflammatory pain in both humans and rodents. In rodent sensory neurons, activation of B1 and B2 bradykinin receptors induces neuronal hyperexcitability. Recent evidence suggests that human and rodent dorsal root ganglia (DRG), which contain the cell bodies of sensory neurons, differ in the expression and function of key GPCRs and ion channels; whether bradykinin receptor expression and function are conserved across species has not been studied in depth. ⋯ Using patch-clamp electrophysiology, we found that acute bradykinin increases the excitability of human sensory neurons, whereas prolonged exposure to bradykinin decreases neuronal excitability in a subpopulation of human DRG neurons. Finally, our analyses suggest that donor's history of chronic pain and age may be predictors of higher B1 receptor expression in human DRG neurons. Together, these results indicate that acute bradykinin-induced hyperexcitability, first identified in rodents, is conserved in humans and provide further evidence supporting bradykinin signaling as a potential therapeutic target for treating pain in humans.
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Randomized Controlled Trial
Vaso-occlusive crisis pain intensity, frequency, and duration: which best correlates with health-related quality of life in adolescents and adults with sickle cell disease?
In a cross-sectional analysis of baseline data from a randomized clinical trial, we studied 198 adolescents and adults aged 15+ with sickle cell disease. Interest was in assessing the relative strengths of the relationship of vaso-occlusive crisis (VOC) pain domains of intensity, frequency, and duration, with health-related quality of life (HRQOL). Variation in psychosocial, physical function, and pain expression domains of HRQOL was partially explained by frequency, intensity, and duration of VOC pain, separately and together, over and above differences in age, sex, genotype, and organ system damage. ⋯ Vaso-occlusive crisis pain frequency explained the most variation, when simultaneously considering VOC intensity and duration, except for stiffness , where duration was most predictive. Yet VOC pain intensity, and even VOC duration, also contributed to variability in HRQOL. We recommend that for most purposes, because all 3 VOC pain domains contribute to variability in HRQOL, all 3 domains should be assessed and interventions should be targeted to improve all 3 domains to maximize HRQOL outcomes (Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT02197845 ).