Continuing medical education.
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Biomedical subjects
M E Johnson
Publications and source records attributed to M E Johnson.
How reliable is computerized assessment of readability?
To assess the consistency and comparability of readability software programs, four software programs (Corporate Voice, Grammatix IV, Microsoft Word for Windows, and RightWriter) were compared. Standard materials included 28 pieces of printed educational materials on human immunodeficiency virus/acquired immunodeficiency syndrome distributed nationally and the Gettysburg Address. Statistical analyses for the educational materials revealed that each of the three formulas assessed (Flesch-Kincaid, Flesch Reading Ease, and Gunning Fog Index) provided significantly different grade equivalent scores and that the Microsoft Word program provided significantly lower grade levels and was more inconsistent in the scores provided. For the Gettysburg Address, considerable variation was revealed among formulas, with the discrepancy being up to two grade levels. When averaging across formulas, there was a variation of 1.3 grade levels between the four software programs. Given the variation between formulas and programs, implications for decisions based on results of these software programs are provided.
Analysis of Variance↗
The effect of the neurolytic agent ethanol on cytoplasmic calcium in arterial smooth muscle and endothelium.
BACKGROUND AND OBJECTIVES: Celiac plexus neurolysis, although effective in relieving pain associated with upper abdominal malignancy, occasionally results in paraplegia. Diffusion of the neurolytic agent to arteries supplying the spinal cord has been postulated as a cause, and previous studies with isolated lumbar segmental arteries have demonstrated contraction in response to ethanol and phenol. The mechanism of this contractile effect is unknown, but a role for insular free calcium (Ca2+i) is suggested by the known involvement of Ca2+i in both smooth muscle vasoconstriction and toxic cell injury. The authors sought to determine whether nontoxic concentrations of ethanol cause a direct elevation of Ca2+i in arterial smooth muscle and endothelium. METHODS: Primary cultures of human aortic smooth muscle and endothelial cells were studied to determine the direct effect of ethanol independent of interactions with agonists or contractile proteins. Ca2+i levels were determined in single cells with digitized video fluorescence microscopy, using ratio imaging of the Ca2+i-sensitive fluorophore fura-2. RESULTS: In aortic smooth muscle cells, initial Ca2+i was 98 +/- 41 nM (n = 59 cells). Histamine (10 microM) as a positive control caused an increase in Ca2+i, as expected. Ethanol alone, at doses of 2-5% (v/v) also caused a sustained elevation in Ca2+i of physiologically significant magnitude. Ethanol at doses of 5% or lower did not cause any visibly apparent injury within 30 minutes. In contrast, 10% or higher ethanol doses quickly caused membrane blebbing, a sign of toxic injury, followed by cell death within 20 minutes. Aortic endothelial cells were more resistant to ethanol than smooth muscle cells, in terms of both Ca2+i elevation and cell death. CONCLUSIONS: Ethanol, even at nontoxic concentrations, has a direct effect on aortic smooth muscle Ca2+i, large enough to be associated with significant vasoconstriction. The findings suggest a possible role for pharmacologic agents that preserve Ca2+i homeostasis in protecting against neurolysis-induced paraplegia, although additional study is required before clinical application is appropriate.
Calcium↗
Saliva contamination of dentin bonding agents.
This study examined the shear bond strength to dentin of two dentin bonding agents when contaminated with a measured amount of saliva at various stages in their application procedure. Eighty extracted human third molar teeth were randomly separated into four groups of 10 for each of the dentin bonding systems tested (All-Bond 2, Scotchbond Multi-Purpose). Group A specimens were not contaminated; primer/adhesive/resin were applied according to manufacturers' instructions. In Group B, samples were contaminated for 15 seconds with fresh whole human saliva, and then forcibly dried with a blast of oil-free air; this occurred after application of the primer but prior to application of adhesive. In Group C, contamination occurred after application of adhesive, prior to application of resin. In Group D, saliva was allowed to contaminate the surface as the primer was being applied, without forcible removal. Specimens were then thermocycled, mounted, and tested in shear on an Instron at 7 days. Bond strengths in MPa were obtained, and data were analyzed using a one-way ANOVA, at the P = 0.05 level of significance. Although shear bond strengths were lowered in saliva-contaminated samples, there was no statistically significant difference between group means.
Analysis of Variance↗