In vivo expression technology (IVET) has been widely used to study gene expression of human bacterial pathogens in animal models, but has heretofore not been used in humans to our knowledge. As part of ongoing efforts to understand Vibrio cholerae pathogenesis and develop improved V. cholerae vaccines, we have performed an IVET screen in humans for genes that are preferentially expressed by V. cholerae during infection. A library of 8,734 nontoxigenic V. cholerae strains carrying transcriptional fusions of genomic DNA to a resolvase gene was ingested by five healthy adult volunteers. Transcription of the fusion leads to resolvase-dependent excision of a sacB -containing cassette and thus the selectable phenotype of sucrose resistance (Suc ^R ). A total of ≈20,000 Suc ^R isolates, those carrying putative in vivo -induced fusions, were recovered from volunteer stool samples. Analysis of the fusion junctions from >7,000 Suc ^R isolates from multiple samples from multiple volunteers identified 217 candidate genes for preferential expression during human infection. Of genes or operons induced in three or more volunteers, the majority of those tested (65%) were induced in an infant mouse model. VC0201 ( fhuC ), which encodes the ATPase of a ferrichrome ABC transporter, is one of the identified in vivo -induced genes and is required for virulence in the mouse model.

Infectious diarrhea is a major contributor of child morbidity and mortality in developing nations. Murine models to study the pathogenesis of infectious diarrhea caused by organisms such as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are not fully characterized. More emphasis has been placed on infection of mice with the murine specific pathogen Citrobacter rodentium. While these three organisms are genetically related they are not identical. Our goal was to better characterize the murine model of EPEC and EHEC infection by using bioluminescent bacteria to determine temporal and spatial colonization of these two human pathogens. EPEC and EHEC were transformed with a bacterial luciferase expression plasmid containing the constitutive OmpC promoter. C57BL/6 mice were orally inoculated with bioluminescent EPEC or EHEC and bacterial localization in the intestine was monitored ex vivo and in vivo by IVIS. At 3 days after infection, EPEC, EHEC and Citrobacter rodentium were all localized in the cecum and colon. EPEC colonization peaked at day 2-3 and was undetectable by day 7. The bioluminescent EPEC adheres to the cecum and colon of the mouse intestine. However, when EPEC infected mice were administered xylazine/ketamine for in vivo live imaging, the EPEC persisted at high densities for up to 31 days. This is the first report of a bioluminescent imaging of luciferase expressing EPEC in a mouse model.

Applied memory research in the field of cognitive and educational psychology has generated a large body of data to support the use of spacing and testing to promote long-term or durable memory. Despite the consensus of this scientific community, most learners, including radiology residents, do not utilize these tools for learning new information. We present a discussion of these parallel and synergistic learning techniques and their incorporation into a software platform, called Spaced Radiology, which we created for teaching radiology residents. Specifically, this software uses these evidence-based strategies to teach pediatric radiology through a flashcard deck system.

In this article, we describe the basics of how magnetic resonance urography (MRU) is performed in the pediatric population as well as the common indications and relative performance compared to standard imaging modalities.

Live, attenuated Vibrio cholerae vaccines can induce potent immune responses after only a single oral dose. The strategy of harnessing these strains

Imaging plays an important role in the diagnosis and management of focal liver lesions, and patient-related factors such as age, size, cardiac function, and ability to cooperate for imaging examina... A differential diagnosis based on a patient’s age, clinical presentation, and serum α-fetoprotein level will help guide the initial imaging workup in children with a liver lesion. Children vary sig...