Pain
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The objective of this study was to investigate whether incident opioid use is associated with an increased risk of hip fractures among community-dwelling persons with Alzheimer disease (AD) and to assess the association in terms of duration of use and opioid strength. Among community-dwelling persons with AD diagnosed in 2010 to 2011 (N = 23,100), a matched cohort study comparing incident opioid users (N = 4750) with opioid nonusers (N = 4750) was constructed. Matching was based on age, sex, and time since AD diagnosis at opioid initiation. ⋯ The risk was observed during the first 2 months of use (IPT-weighted HR 2.37, 1.04-5.41) and attenuated after that. The results suggest an increase in the risk of hip fracture by increasing opioid strength; weak opioids IPT-weighted HR 1.75 (0.91-3.35), buprenorphine IPT-weighted HR 2.10 (1.41-3.13), and strong opioids IPT-weighted HR 2.89 (1.32-6.32). Further research is needed to find out whether the risk of injurious falls is avoidable by slow titration of opioid doses in the beginning of treatment.
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Studies have shown that moderate alcohol consumption is strongly associated with reduced reporting of chronic widespread pain (CWP). The study designs used, however, are prone to confounding and are not able to establish the direction of causality. The current study overcomes these problems using the Mendelian randomisation design to determine the effect of alcohol consumption on the likelihood of reporting CWP. ⋯ Persons with "GG" genotype had an increased risk of CWP (odds ratio [OR] 1.17, 99% confidence interval 1.01-1.35) and were more likely to consume alcohol weekly (OR 1.76, 1.70-1.81) compared to those with "AA/AG" genotype. Weekly consumption of alcohol was associated with reduced risk of CWP (OR 0.33, 0.31-0.35), but instrumental variable analysis did not show a causal effect of alcohol consumption on reducing CWP (OR 1.29, 0.96-1.74). An interpretation of observational population studies as showing a protective effect of alcohol on CWP is not supported.
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Sensitization of the transient receptor potential ion channel vanilloid 1 (TRPV1) is critically involved in inflammatory pain. To date, manifold signaling cascades have been shown to converge onto TRPV1 and enhance its sensitization. However, many of them also play a role for nociceptive pain, which limits their utility as targets for therapeutic intervention. ⋯ Alongside, we identify numerous novel and pain state-dependent binding partners of native TRPV1 in dorsal root ganglia. These data represent a unique resource on the dynamics of the TRPV1 interactome and facilitate mechanistic insights into TRPV1 regulation. We propose that inflammation-related differences in the TRPV1 interactome identified here could be exploited to specifically target inflammatory pain in the future.
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Ocular pain is a core symptom of inflammatory or traumatic disorders affecting the anterior segment. To date, the management of chronic ocular pain remains a therapeutic challenge in ophthalmology. The main endogenous opioids (enkephalins) play a key role in pain control but exhibit only transient analgesic effects due to their rapid degradation. ⋯ Chronic PL265 topical administration also decreased Iba1 and neuronal injury marker (ATF3) staining in the nucleus of primary sensory neurons of ipsilateral trigeminal ganglion. These results open a new avenue for ocular pain treatment based on the enhancement of endogenous opioid peptides' analgesic effects in tissues of the anterior segment of the eye. Dual enkephalinase inhibitor PL265 seems to be a promising topical treatment for safe and effective alleviation of ocular pain and inflammation.