Pain
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Comparative Study
Comparison of two psychometric scaling methods for ratings of acute musculoskeletal pain.
Psychometric theory allows interindividual comparisons by scaling differences among subjects with respect to some psychological attribute. The most widely used psychometric scaling method is classical test theory. The properties of classical test theory pain scores are limited to the observed range of pain scores in a given sample, to the specific conditions in a given sample that are the source of pain (e.g. surgery vs. cancer), and to a particular pain survey. ⋯ The psychometric scaling methods were compared using standardized residuals (data fit), standard errors of measurement (score precision), and a graphical plot of predicted scores against scale scores (bias). The item response theory scores demonstrated better data fit and less bias than did the classical test theory scores. In addition to superior psychometric properties, item response theory scores have several other important theoretical and practical advantages.
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Comparative Study
State-dependent block of voltage-gated Na+ channels by amitriptyline via the local anesthetic receptor and its implication for neuropathic pain.
Amitriptyline is a tricyclic antidepressant, which also alleviates various pain syndromes at its therapeutic plasma concentration (0.36-0.90 microM). Accumulated evidence suggests that such efficacy may be due to block of voltage-gated Na(+) channels. The Na(+) channel alpha-subunit protein consists of four homologous domains (D1-D4), each with six transmembrane segments (S1-S6). ⋯ The open-channel block by amitriptyline has the highest affinity, with a 50% inhibitory concentration (IC(50)) of 0.26 microM. The inactivated-channel block by amitriptyline had a weaker affinity (0.51 microM), whereas the resting-channel displayed the weakest affinity (33 microM). We hypothesize that selective block of both persistent late openings and the inactivated state of neuronal Na(+) channel isoforms by amitriptyline also occurs at its therapeutic concentration and likely contributes to its efficacy in pain syndromes.
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Comparative Study
Contributions of the anterior cingulate cortex and amygdala to pain- and fear-conditioned place avoidance in rats.
The pain experience includes a sensory-discriminative and an affective-emotional component. The sensory component of pain has been extensively studied, while data about the negative affective component of pain are quite limited. The anterior cingulate cortex (ACC), and amygdala are thought to be key neural substrates underlying emotional responses. ⋯ However, the decrease in the magnitude of S-CPA occurred only in the amygdala, but not ACC lesioned animals. Neither ACC nor amygdala lesion significantly changed formalin-induced acute nociceptive behaviors. These results suggest that the amygdala is involved in both pain- and fear-related negative emotion, and the ACC might play a critical role in the expression of pain-related negative emotion.