Color-coding improves parental understanding of body mass index charting.

OBJECTIVE: To assess parental understanding of body mass index (BMI) and BMI percentiles by using standard versus color-coded charts; to investigate how parental literacy and/or numeracy (quantitative skills) affects that understanding. METHODS: A convenience sample of 163 parents of children aged 2 to 8 years at 2 academic pediatric centers completed a demographics questionnaire, the mathematics portion of the Wide Range Achievement Test (WRAT-3R), the Short Test of Functional Health Literacy in Adults (S-TOFHLA), and an "Understanding BMI" questionnaire, which included parallel BMI charting questions to compare understanding of standard versus color-coded BMI charting. Outcomes included parental-reported versus actual understanding of BMI, the odds (obtained by generalized estimating equations) of answering parallel questions correctly by using standard versus color-coded charting, and odds of answering questions correctly on the basis of numeracy and literacy. RESULTS: Many parents (60%) reported knowing what BMI was, but only 30% could define it even roughly correctly. When parents used color-coded charts, they had greater odds of answering parallel BMI charting questions correctly than when they used standard charts (mean, 88% vs 65% correct; pooled adjusted odds ratio, 4.32; 95% confidence interval, 3.14-5.95; P < .01). Additionally, parents with lower numeracy (K-5 level) benefited more from color-coded charts (increased from 51% to 81% correct) than did higher numeracy parents (high school level or greater), who performed well with both charts (89% vs 99% correct). CONCLUSIONS: Parents consistently performed better with color-coded than standard BMI charts. Color-coding was particularly helpful for lower numeracy parents. Future studies should investigate whether these results translate into the office setting and whether understanding motivates parents to implement important lifestyle changes.

MutL-catalyzed ATP hydrolysis is required at a post-UvrD loading step in methyl-directed mismatch repair.

Methyl-directed mismatch repair is a coordinated process that ensures replication fidelity and genome integrity by resolving base pair mismatches and insertion/deletion loops. This post-replicative event involves the activities of several proteins, many of which appear to be regulated by MutL. MutL interacts with and modulates the activities of MutS, MutH, UvrD, and perhaps other proteins. The purified protein catalyzes a slow ATP hydrolysis reaction that is essential for its role in mismatch repair. However, the role of the ATP hydrolysis reaction is not understood. We have begun to address this issue using two point mutants: MutL-E29A, which binds nucleotide but does not catalyze ATP hydrolysis, and MutL-D58A, which does not bind nucleotide. As expected, both mutants failed to complement the loss of MutL in genetic assays. Purified MutL-E29A protein interacted with MutS and stimulated the MutH-catalyzed nicking reaction in a mismatch-dependent manner. Importantly, MutL-E29A stimulated the loading of UvrD on model substrates. In fact, stimulation of UvrD-catalyzed unwinding was more robust with MutL-E29A than the wild-type protein. MutL-D58A, on the other hand, did not interact with MutS, stimulate MutH-catalyzed nicking, or stimulate the loading of UvrD. We conclude that ATP-bound MutL is required for the incision steps associated with mismatch repair and that ATP hydrolysis by MutL is required for a step in the mismatch repair pathway subsequent to the loading of UvrD and may serve to regulate helicase loading.

The DNA binding activity of MutL is required for methyl-directed mismatch repair in Escherichia coli.

The DNA binding properties of the mismatch repair protein MutL and their importance in the repair process have been controversial for nearly two decades. We have addressed this issue using a point mutant of MutL (MutL-R266E). The biochemical and genetic data suggest that DNA binding by MutL is required for dam methylation-directed mismatch repair. We demonstrate that purified MutL-R266E retains wild-type biochemical properties that do not depend on DNA binding, such as basal ATP hydrolysis in the absence of DNA and the ability to interact with other mismatch repair proteins. However, purified MutL-R266E binds DNA poorly in vitro as compared with MutL, and consistent with this observation, its DNA-dependent biochemical activities, like DNA-stimulated ATP hydrolysis and helicase II stimulation, are severely compromised. In addition, there is a modest effect on stimulation of MutH-catalyzed nicking. Finally, genetic assays show that MutL-R266E has a strong mutator phenotype, demonstrating that the mutant is unable to function in dam methylation-directed mismatch repair in vivo.