Post-secretional activation of Protease IV by quorum sensing in Pseudomonas aeruginosa.

Protease IV (PIV), a key virulence factor of Pseudomonas aeruginosa is a secreted lysyl-endopeptidase whose expression is induced by quorum sensing (QS). We found that PIV expressed in QS mutant has severe reduction of activity in culture supernatant (CS), even though it is overexpressed to high level. PIV purified from the QS mutant (M-PIV) had much lower activity than the PIV purified from wild type (P-PIV). We found that the propeptide cleaved from prepro-PIV was co-purified with M-PIV, but never with P-PIV. Since the activity of M-PIV was restored by adding the CS of QS-positive and PIV-deficient strain, we hypothesized that the propeptide binds to and inhibits PIV, and is degraded to activate PIV by a QS-dependent factor. In fact, the CS of the QS-positive and PIV-deficient strain was able to degrade the propeptide. Since the responsible factor should be a QS-dependently expressed extracellular protease, we tested QS-dependent proteases of P. aeruginosa and found that LasB (elastase) can degrade the propeptide and activate M-PIV. We purified the propeptide of PIV and confirmed that the propeptide can bind to and inhibit PIV. We suggest that PIV is post-secretionally activated through the extracellular degradation of the propeptide by LasB, a QS-dependent protease.

Reduced harm or another gateway to smoking? source, message, and information characteristics of E-cigarette videos on YouTube.

E-cigarettes are widely promoted on the Internet, but little is known about what kinds of information about them are available online. This study examines message, source, and health information characteristics of e-cigarette videos on the popular online video-sharing platform YouTube. A content analysis of 365 e-cigarette videos indicates that 85% of the videos were sponsored by marketers. These videos highlight e-cigarettes' economic and social benefits, featuring a low level of fear appeal and negative message valence and a high level of marketing information about e-cigarette products. They also convey certain health claims that have been proscribed by the U.S. Food and Drug Administration, the prevalence of which warrants ongoing monitoring and regulatory guidelines for online e-cigarette marketing.

Consistency of nutrition recommendations for foods marketed to children in the United States, 2009-2010.

INTRODUCTION: Food marketing has emerged as an environmental factor that shapes children's dietary behaviors. "Advergames," or free online games designed to promote branded products, are an example of evolving food marketing tactics aimed at children. Our primary objective was to classify foods marketed to children (aged 2-11 y) in advergames as those meeting or not meeting nutrition recommendations of the US Department of Agriculture (USDA), Food & Drug Administration (FDA), Center for Science in the Public Interest (CSPI), and the Institute of Medicine (IOM). We document the consistency of classification of those foods across agency guidelines and offer policy recommendations. METHODS: We used comScore Media Builder Metrix to identify 143 websites that marketed foods (n = 439) to children aged 2 to 11 years through advergames. Foods were classified on the basis of each of the 4 agency criteria. Food nutrient labels provided information on serving size, calories, micronutrients, and macronutrients. RESULTS: The websites advertised 254 meals, 101 snacks, and 84 beverages. Proportions of meals and snacks meeting USDA and FDA recommendations were similarly low, with the exception of saturated fat in meals and sodium content in snacks. Inconsistency in recommendations was evidenced by only a small proportion of meals and fewer snacks meeting the recommendations of all the agencies per their guidelines. Beverage recommendations were also inconsistent across the 3 agencies that provide recommendations (USDA, IOM, and CSPI). Most (65%-95%) beverages advertised in advergames did not meet some of these recommendations. CONCLUSION: Our findings indicate that a large number of foods with low nutritional value are being marketed to children via advergames. A standardized system of food marketing guidance is needed to better inform the public about healthfulness of foods advertised to children.