Pain
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Chronic pain is a significant health problem associated with disability and reduced quality of life. Current management of chronic pain is inadequate with only modest effects of pharmacological interventions. Thus, there is a need for the generation of analgesics for treating chronic pain. ⋯ Sustained release of SARM, from the microparticle formulation, was observed both in vitro and in vivo for 4 weeks. Selective androgen receptor modulator treatment produced no cardiac or liver toxicity and did not produce rewarding behaviors. These studies demonstrate that SARM-loaded microparticles, which release drug for a sustained period, alleviate muscle pain, are safe, and may serve as a potential therapeutic for chronic muscle pain.
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Meta Analysis
Stress biomarkers in individuals with fibromyalgia syndrome: a systematic review with meta-analysis.
Evidence suggests an involvement of hypothalamic-pituitary-adrenal (HPA) axis dysregulation in the development and maintenance of fibromyalgia syndrome (FMS). However, studies on the stress response via the HPA-axis in individuals with FMS show conflicting results. To better understand the relationship between FMS and HPA-axis dysregulation, we (1) systematically summarized the current level of evidence on HPA biomarkers in individuals with FMS compared with individuals without and (2) evaluated whether FMS is associated with a specific pattern of HPA dysregulation. ⋯ However, heterogeneity of data was high with significant evidence for publication bias. Overall, the data are compatible with association of FMS with adrenocortical hypofunction in the presence of increased sympathetic tone. However, the data are partially contradictory, so it must be assumed that the data are highly dependent on the respective study designs, patient samples, and analytical methods and do not necessarily demonstrate an abnormal HPA-axis function in FMS.
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Quantitative sensory testing (QST) is increasingly used in pediatric chronic pain; however, assessment in youth with acute musculoskeletal (MSK) pain is limited. This study evaluated the feasibility, reliability, and sources of variability of a brief QST protocol in 2 clinical samples of youth with acute MSK pain. Participants were 277 youth (M age = 14.5 years, SD = 2.0, range = 11-18 years, 59% female, 81% non-Hispanic) across 3 geographic study sites who completed a QST protocol assessing pressure and thermal pain sensitivity, temporal summation of pain, and conditioned pain modulation 8 weeks after MSK surgery (n = 100) or within 4 weeks after an acute MSK injury (n = 177). ⋯ Hispanic youth had higher pressure and heat pain thresholds (d = 0.37-0.45) and pain ratings for cold pain tolerance (d = 0.54) compared with non-Hispanic youth. No significant differences were observed in QST values by sex or personal contextual factors at the time of assessment (momentary pain, menstrual period, use of pain medications). Overall findings demonstrate feasibility of a brief QST protocol with youth with diverse acute MSK pain and data provide initial support for the reliability of this QST protocol for multisite research studies.
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The purpose of this study was to examine the dyadic and individual level effects of parent and child pain catastrophizing on child health-related quality of life (HRQOL) in pediatric sickle cell disease. Questionnaires assessing child pain frequency, child and parent pain catastrophizing, and child HRQOL were completed by youth and their primary caregiver. A Common Fate Model was estimated to test the dyadic level relationship between parent and child pain catastrophizing and child HRQOL. ⋯ Individual level effects were net of same-rater bias, which was significant for both parents and children. Both the unique and the overlapping aspects of parent and child pain catastrophizing are significant contributors to associations with child HRQOL, such that higher levels of pain catastrophizing are associated with worse child HRQOL. Findings suggest the need for multipronged intervention targeting factors common to parent-child dyads and factors unique to parents and children, respectively.
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Low-frequency sinusoidal current applied to human skin evokes local axon reflex flare and burning pain, indicative of C-fibre activation. Because topical cooling works well as a local analgesic, we examined the effect of cooling on human pain ratings to sinusoidal and rectangular profiles of constant current stimulation. Unexpectedly, pain ratings increased upon cooling the skin from 32 to 18°C. ⋯ However, for sinusoidal stimulus profiles, cooling enabled a more effective integration of low-intensity currents over tens of milliseconds resulting in a delayed initiation of action potentials. Our findings indicate that the paradoxical cooling-induced enhancement of electrically evoked pain in people can be explained by an enhancement of C-fibre responsiveness to slow depolarization at lower temperatures. This property may contribute to symptoms of enhanced cold sensitivity, especially cold allodynia, associated with many forms of neuropathic pain.