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OBJECTIVE: Prevalence of smoking combustible cigarettes has decreased, but rates of nicotine vaping among adolescents and young adults have increased dramatically. Vaping is associated with acute health problems and exposes users to toxic metals with unknown long-term consequences. Research on factors influencing vaping is needed to inform development of effective prevention and intervention methods. Nicotine vaping expectancies, or expected effects related to vaping, may be an important target as they can predict vaping behaviors. The purpose of this study was to examine nicotine expectancy activation patterns with corresponding nicotine vaping behaviors. METHOD: Using methods from alcohol expectancy research, we applied a memory model approach to identifying nicotine vaping expectancies and modeling organization and activation patterns in relation to frequency of nicotine vaping. We created a memory model-based nicotine expectancy measure based on information from 200 adolescents in 8th and 12th grades, and 429 college students. Our expectancy measure was completed by a second sample of 862 college students. RESULTS: We mapped expectancies into network format using Individual Differences Scaling (INDSCAL) and we modeled likely paths of expectancy activation using Preference Mapping (PREFMAP). Non-users primarily emphasized a positive-negative expectancy dimension and were more likely to activate expectancies of negative internal experiences in relation to vaping. Students who vaped nicotine daily or almost daily primarily emphasized an external appearance-internal experience expectancy dimension and were more likely to activate expectancies of negative affect reduction and withdrawal relief. CONCLUSIONS: Our results identify specific targets for expectancy-based prevention and intervention methods that have the potential to be as effective as similar approaches to preventing and reducing alcohol use.
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BACKGROUND & AIMS: Helicobacter pylori infection is the main risk factor for gastric cancer. We characterized the interactions of H pylori with gastric epithelial progenitor and stem cells in humans and mice and investigated how these interactions contribute to H pylori-induced pathology. METHODS: We used quantitative confocal microscopy and 3-dimensional reconstruction of entire gastric glands to determine the localizations of H pylori in stomach tissues from humans and infected mice. Using lineage tracing to mark cells derived from leucine-rich repeat-containing G-protein coupled receptor 5-positive (Lgr5(+)) stem cells (Lgr5-eGFP-IRES-CreERT2/Rosa26-TdTomato mice) and in situ hybridization, we analyzed gastric stem cell responses to infection. Isogenic H pylori mutants were used to determine the role of specific virulence factors in stem cell activation and pathology. RESULTS: H pylori grow as distinct bacterial microcolonies deep in the stomach glands and interact directly with gastric progenitor and stem cells in tissues from mice and humans. These gland-associated bacteria activate stem cells, increasing the number of stem cells, accelerating Lgr5(+) stem cell proliferation, and up-regulating expression of stem cell-related genes. Mutant bacteria with defects in chemotaxis that are able to colonize the stomach surface but not the antral glands in mice do not activate stem cells. In addition, bacteria that are unable to inject the contact-dependent virulence factor CagA into the epithelium colonized stomach glands in mice, but did not activate stem cells or produce hyperplasia to the same extent as wild-type H pylori. CONCLUSIONS: H pylori colonize and manipulate the progenitor and stem cell compartments, which alters turnover kinetics and glandular hyperplasia. Bacterial ability to alter the stem cells has important implications for gastrointestinal stem cell biology and H pylori-induced gastric pathology.