Image interpretation: Learning analytics-informed education opportunities.

OBJECTIVES: Using a sample of pediatric chest radiographs (pCXR) taken to rule out pneumonia, we obtained diagnostic interpretations from physicians and used learning analytics to determine the radiographic variables and participant review processes that predicted for an incorrect diagnostic interpretation. METHODS: This was a prospective cross-sectional study. A convenience sample of frontline physicians with a range of experience levels interpreted 200 pCXR presented using a customized online radiograph presentation platform. Participants were asked to determine absence or presence (with respective location) of pneumonia. The pCXR were categorized for specific image-based variables potentially associated with interpretation difficulty. We also generated heat maps displaying the locations of diagnostic error among normal pCXR. Finally, we compared image review processes in participants with higher versus lower levels of clinical experience. RESULTS: We enrolled 83 participants (20 medical students, 40 postgraduate trainees, and 23 faculty) and obtained 12,178 case interpretations. Variables that predicted for increased pCXR interpretation difficulty were pneumonia versus no pneumonia (ß = 8.7, 95% confidence interval [CI] = 7.4 to 10.0), low versus higher visibility of pneumonia (ß = -2.2, 95% CI = -2.7 to -1.7), nonspecific lung pathology (ß = 0.9, 95% CI = 0.40 to 1.5), localized versus multifocal pneumonia (ß = -0.5, 95% CI = -0.8 to -0.1), and one versus two views (ß = 0.9, 95% CI = 0.01 to 1.9). A review of diagnostic errors identified that bony structures, vessels in the perihilar region, peribronchial thickening, and thymus were often mistaken for pneumonia. Participants with lower experience were less accurate when they reviewed one of two available views (p < 0.0001), and accuracy of those with higher experience increased with increased confidence in their response (p < 0.0001). CONCLUSIONS: Using learning analytics, we identified actionable learning opportunities for pCXR interpretation, which can be used to allow for a customized weighting of which cases to practice. Furthermore, experienced-novice comparisons revealed image review processes that were associated with greater diagnostic accuracy, providing additional insight into skill development of image interpretation.

VacA promotes CagA accumulation in gastric epithelial cells during Helicobacter pylori infection.

Helicobacter pylori (H. pylori) is the causative agent of gastric cancer, making it the only bacterium to be recognized as a Class I carcinogen by the World Health Organization. The virulence factor cytotoxin associated gene A (CagA) is a known oncoprotein that contributes to the development of gastric cancer. The other major virulence factor vacuolating cytotoxin A (VacA), disrupts endolysosomal vesicular trafficking and impairs the autophagy pathway. Studies indicate that there is a functional interplay between these virulence factors by unknown mechanisms. We show that in the absence of VacA, both host-cell autophagy and the proteasome degrade CagA during infection with H. pylori. In the presence of VacA, CagA accumulates in gastric epithelial cells. However, VacA does not affect proteasome function during infection with H. pylori suggesting that VacA-disrupted autophagy is the predominant means by which CagA accumulates. Our studies support a model where in the presence of VacA, CagA accumulates in dysfunctional autophagosomes providing a possible explanation for the functional interplay of VacA and CagA.

The Use of 5-Aminosalicylic Acid in Children and Adolescents With Inflammatory Bowel Disease.

BACKGROUND: In ulcerative colitis (UC) 5-aminosalicylic acid (5-ASA) is recommended as primary therapy for mild to moderate disease. Topical 5-ASA has been proven especially effective. In Crohn's disease (CD) the evidence for a beneficial role of 5-ASA is weak. We investigated the use of topical and systemic 5-ASA therapy in children and adolescents with inflammatory bowel disease. MATERIALS AND METHODS: Data of patients younger than 18 years, registered between April 2008 and December 2015 in the Swiss Inflammatory Bowel Disease Cohort, were analyzed. RESULTS: Three hundred twenty pediatric inflammatory bowel disease patients were included; 189 with CD and 131 with UC. Over one third of UC patients [51 (39%)] received topical 5-ASA therapy and 43 (33%) received combination therapy during their disease course. UC patients with left-sided colitis or proctitis were more likely to receive topical or combination therapy as compared with patients with pancolitis (P<0.001 and <0.001, respectively). An increase in the use of topical 5-ASA therapy in UC patients was noted over time from 5% to 38%. Forty-seven percent of CD patients were treated with oral 5-ASA during their disease course. The usage was stable over time at approximately 15% to 20%. CONCLUSIONS: In recent years a very positive trend showing an increase in topical 5-ASA therapy in children and adolescents with UC has been observed. However topical therapy is still used with relative low frequency, especially in patients with a more extensive disease. Conversely, despite weak evidence supporting 5-ASA use in CD patients it has been frequently prescribed. Physicians should continue to encourage their UC patients to use topical therapy.

Helicobacter pylori inhibits dendritic cell maturation via interleukin-10-mediated activation of the signal transducer and activator of transcription 3 pathway.

Helicobacter pylori infects the human gastric mucosa causing a chronic infection that is the primary risk factor for gastric cancer development. Recent studies demonstrate that H. pylori promotes tolerogenic dendritic cell (DC) development indicating that this bacterium evades the host immune response. However, the signaling pathways involved in modulating DC activation during infection remain unclear. Here, we report that H. pylori infection activated the signal transducer and activator of transcription 3 (STAT3) pathway in murine bone marrow-derived DCs (BMDCs) and splenic DCs isolated ex vivo. Isogenic cagA-, cagE-, vacA- and urease-mutants exhibited levels of phosphoSTAT3 that were comparable to in the wild-type (WT) parent strain. H. pylori-infected BMDCs produced increased immunosuppressive IL-10, which activated STAT3 in an autocrine/paracrine fashion. Neutralization of IL-10 prevented H. pylori-mediated STAT3 activation in both BMDCs and splenic DCs. In addition, anti-IL-10 treatment of infected H. pylori-BMDCs was associated with increased CD86 and MHC II expression and enhanced proinflammatory IL-1ß cytokine secretion. Finally, increased CD86 and MHC II expression was detected in H. pylori-infected STAT3 knockout DCs when compared to WT controls. Together, these results demonstrate that H. pylori infection induces IL-10 secretion in DCs, which activates STAT3, thereby modulating DC maturation and reducing IL-1ß secretion. These findings identify a host molecular mechanism by which H. pylori can manipulate the innate immune response to potentially favor chronic infection and promote carcinogenesis.

Phosphatidic acid is required for the constitutive ruffling and macropinocytosis of phagocytes.

Macrophages and dendritic cells continuously survey their environment in search of foreign particles and soluble antigens. Such surveillance involves the ongoing extension of actin-rich protrusions and the consequent formation of phagosomes and macropinosomes. The signals inducing this constitutive cytoskeletal remodeling have not been defined. We report that, unlike nonphagocytic cells, macrophages and immature dendritic cells have elevated levels of phosphatidic acid (PA) in their plasma membrane. The plasmalemmal PA is synthesized by phosphorylation of diacylglycerol, which is in turn generated by a G protein-stimulated phospholipase C. Inhibition of diacylglycerol kinase activity results in the detachment of T-cell lymphoma invasion and metastasis-inducing protein 1 (TIAM1)-a Rac guanine exchange factor-from the plasma membrane, thereby depressing Rac activity and abolishing the constitutive ruffling and macropinocytosis that characterize macrophages and immature dendritic cells. Accumulation of PA and binding of TIAM1 to the membrane require the activity of phosphatidylinositol-4,5-bisphosphate 3-kinase. Thus a distinctive, constitutive pathway of PA biosynthesis promotes the actin remodeling required for immune surveillance.

Cell culture-based assays to test for bacterial adherence and internalization.

Adherence and internalization of Helicobacter pylori into epithelial cells is a recently recognized event in the pathogen's life cycle.

Cell culture assays to evaluate bacterial toxicity and virulence.

Helicobacter pylori CagA and VacA are two critical virulence factors that modulate disease severity in the infected host. The following chapter outlines methods employed to study the effects of these virulence factors on several key signaling pathways in epithelial cells.