Clostridium difficile, the causative agent of nosocomial antibiotic-associated diarrhoea and pseudomembranous colitis, possesses two main virulence factors: the large clostridial cytotoxins A and B. It has been proposed that toxin B is cleaved by a cytosolic factor of the eukaryotic target cell during its cellular uptake. Here we report that cleavage of not only toxin B, but also all other large clostridial cytotoxins, is an autocatalytic process dependent on host cytosolic inositolphosphate cofactors. A covalent inhibitor of aspartate proteases, 1,2-epoxy-3-(p-nitrophenoxy)propane, completely blocked toxin B function on cultured cells and was used to identify its catalytically active protease site. To our knowledge this is the first report on a bacterial toxin that uses eukaryotic signals for induced autoproteolysis to deliver its toxic domain into the cytosol of target cells. On the basis of our data, we present an integrated model for the uptake and inositolphosphate-induced activation of toxin B.
Mobile technologies are emerging as a valuable tool to collect and assess dietary intake. Adolescents readily accept and adopt new technologies, hence, a food record application (FRapp) may provide an accurate mechanism to monitor dietary intake. We examined the usability of a FRapp in 17 free‐living adolescents. Participants (11 – 14 y) received detailed instructions and were asked to capture before and after images of all foods and beverages consumed, and enter text descriptions using the FRapp for 3–7 days. Sixteen participants used the FRapp and 1 used the phone's native camera function to capture food images. A total of 109 meals were recorded, of which 40% included a post meal image. 62% of images included all foods, beverages and a fiducial marker. Text was recorded for 10 meals without images. Only 6 participants recorded 3 meals a day. One participant reported the FRapp as being too difficult (1 meal recorded) and another recorded all meals as snacks. Of the meals recorded, 25, 24, 25, and 35 were breakfast, lunch, dinner, and snacks, respectively. These data suggest that a FRapp can be useful for dietary intake assessment in adolescents. A detailed interactive training session, including a test meal, may increase the inclusion of all foods and beverages in the images. Additionally, a trigger is needed to remind participants to take a post image.Grant Funding Source: ARS‐USDA
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.