Objectives: The Wong-Baker FACES Pain Rating Scale (WBS), used in children to rate pain severity, has been validated outside the emergency department (ED), mostly for chronic pain. The authors validated the WBS in children presenting to the ED with pain by identifying a corresponding mean value of the visual analog scale (VAS) for each face of the WBS and determined the relationship between the WBS and VAS. The hypothesis was that the pain severity ratings on the WBS would be highly correlated (Spearman's rho > 0.80) with those on a VAS.Methods: This was a prospective, observational study of children ages 8-17 years with pain presenting to a suburban, academic pediatric ED. Children rated their pain severity on a six-item ordinal faces scale (WBS) from none to worst and a 100-mm VAS from least to most. Analysis of variance (ANOVA) was used to compare mean VAS scores across the six ordinal categories. Spearman's correlation (q) was used to measure agreement between the continuous and ordinal scales.Results: A total of 120 patients were assessed: the median age was 13 years (interquartile range [IQR] = 10-15 years), 50% were female, 78% were white, and six patients (5%) used a language other than English at home. The most commonly specified locations of pain were extremity (37%), abdomen (19%), and back ⁄ neck (11%). The mean VAS increased uniformly across WBS categories in increments of about 17 mm. ANOVA demonstrated significant differences in mean VAS across face groups. Post hoc testing demonstrated that each mean VAS was significantly different from every other mean VAS. Agreement between the WBS and VAS was excellent (q = 0.90; 95% confidence interval [CI] = 0.86 to 0.93). There was no association between age, sex, or pain location with either pain score.
Conclusions:The VAS was found to have an excellent correlation in older children with acute pain in the ED and had a uniformly increasing relationship with WBS. This finding has implications for research on pain management using the WBS as an assessment tool.
Vesicle transport in cultured chick motoneurons was studied over a period of 3 days using motion enhanced differential interference contrast (MEDIC) microscopy, an improved version of videoenhanced DIC. After 3 days in vitro (DIV), the average vesicle velocity was about 30% less than after 1 DIV. In observations at 1, 2 and 3 DIV, larger vesicles moved more slowly than small vesicles, and retrograde vesicles were larger than anterograde vesicles. The number of retrograde vesicles increased relative to anterograde vesicles after 3 DIV, but this fact alone could not explain the decrease in velocity, since the slowing of vesicle transport in maturing motoneurons was observed independently for both anterograde and retrograde vesicles. In order to better understand the slowing trend, the distance vs. time trajectories of individual vesicles were examined at a frame rate of 8.3/ s. Qualitatively, these trajectories consisted of short (1-2 s) segments of constant velocity, and the changes in velocity between segments were abrupt (<0.2 s). The trajectories were therefore fit to a series of connected straight lines. Surprisingly, the slopes of theses lines, i.e. the vesicle velocities, were often found to be multiples of ~0.6 µm/s. The velocity histogram showed multiple peaks, which, when fit with Gaussians using a least squares minimization, yielded an average spacing of 0.57 µm/ s (taken as the slope of a fit to peak position vs. peak number, R 2 = 0.994). We propose that the abrupt velocity changes occur when 1 or 2 motors suddenly begin or cease actively participating in vesicle transport. Under this hypothesis, the decrease in average vesicle velocity observed for maturing motoneurons is due to a decrease in the average number of active motors per vesicle.
Gliding assays of motor proteins such as kinesin, dynein, and myosin are commonly carried out with fluorescently labeled microtubules or filamentous actin. In this paper, we show that speckled microtubules (MTs), prepared by copolymerizing 98% unlabeled tubulin with 2% rhodaminelabeled tubulin, can be localized to ±7.4 nm (24 measurements) in images acquired every 125 ms. If the speckled MTs move at about 800 nm/s, 10 images are sufficient to determine their velocity to a precision of ±6.8 nm/s (6 microtubules, 24 measurements). This velocity precision is 4-fold better than manual methods for measuring the gliding velocity of uniformly labeled MTs by endpoint localization. The improved velocity precision will permit the determination of velocity-force curves when 1, 2, and 3 kinesin motors pull a single load in vitro.
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