Background: It is unclear whether Legionella pneumophila possesses phospholipase C (PLC) activity and thereby generates 1,2-diacylglycerol. Results: L. pneumophila possesses three secreted enzymes with PLC activity, PlcA, PlcB, and PlcC, and a plcABC mutant was attenuated in host killing. Conclusion: L. pneumophila encodes three members of a novel PLC family contributing to virulence. Significance: We determined PLC activity for L. pneumophila and defined the characteristics of a novel PLC family present in Legionella, Pseudomonas, and fungi.

BackgroundAlthough cancer screening reduces morbidity and mortality, millions of people worldwide remain unscreened. Social media provide a unique platform to understand public sentiment toward tools that are commonly used for cancer screening.ObjectiveThe objective of our study was to examine public sentiment toward colonoscopy, mammography, and Pap smear and how this sentiment spreads by analyzing discourse on Twitter.MethodsIn this observational study, we classified 32,847 tweets (online postings on Twitter) related to colonoscopy, mammography, or Pap smears using a naive Bayes algorithm as containing positive, negative, or neutral sentiment. Additionally, we characterized the spread of sentiment on Twitter using an established model to study contagion.ResultsColonoscopy-related tweets were more likely to express negative than positive sentiment (negative to positive ratio 1.65, 95% CI 1.51-1.80, P<.001), in contrast to the more positive sentiment expressed regarding mammography (negative to positive ratio 0.43, 95% CI 0.39-0.47, P<.001). The proportions of negative versus positive tweets about Pap smear were not significantly different (negative to positive ratio 0.95, 95% CI 0.87-1.04, P=.18). Positive and negative tweets tended to share lexical features across screening modalities. Positive tweets expressed resonance with the benefits of early detection. Fear and pain were the principal lexical features seen in negative tweets. Negative sentiment for colonoscopy and mammography spread more than positive sentiment; no correlation with sentiment and spread was seen for Pap smear.ConclusionsAnalysis of social media data provides a unique, quantitative framework to better understand the public’s perception of medical interventions that are commonly used for cancer screening. Given the growing use of social media, public health interventions to improve cancer screening should use the health perceptions of the population as expressed in social network postings about tests that are frequently used for cancer screening, as well as other people they may influence with such postings.

The use of diagnostic imaging studies in the emergency setting has increased dramatically over the past couple of decades. The emergency imaging of pregnant and lactating patients poses unique challenges and calls upon the crucial role of radiologists as consultants to the referring physician to guide appropriate use of imaging tests, minimize risk, ensure timely management, and occasionally alleviate unwarranted trepidation. A clear understanding of the risks and benefits involved with various imaging tests in this patient population is vital to achieve this. This review discusses the different safety and appropriateness issues that could arise with the use of ionizing radiation, iodinated-, and gadolinium-based contrast media and radiopharmaceuticals in pregnant and lactating patients. Special considerations such as trauma imaging, safety concerns with magnetic resonance imaging and ultrasound, management of claustrophobia, contrast extravasation, and allergic reactions are also reviewed. The consent process for these examinations has also been described.

No abstract