No abstract

Background Helicobacter pylori ( H. pylori ) infection is associated with remodeling of gastric microbiota. However, comprehensive analyses of the impact of H. pylori infection, eradication therapy and probiotic supplementation on gut microbiota are still lacking. We aimed to provide evidence for clinical decision making. Methods Seventy H. pylori -positive and 35 H. pylori -negative patients (group C) were enrolled. H. pylori -positive patients were randomly assigned to group A (14-day bismuth-containing quadruple therapy) and group B (quadruple therapy supplemented with Clostridium butyricum ). Stool samples of group A and B were collected on day 0, 14 and 56 while stool samples of group C were collected on day 0. Gut microbiota was investigated by 16S rRNA sequencing. Findings The Sobs index (richness estimator) was significantly higher in H. pylori -positive samples than H. pylori -negative samples ( p < .05). Several metabolic pathways were more abundant in H. pylori -positive communities while some disease-associated pathways had higher potential in H. pylori -negative community through KEGG pathway analysis. Abundances of most butyrate-producing bacteria significantly decreased, while several detrimental bacteria increased after eradication therapy. Probiotic supplementation was associated with improved gastrointestinal symptoms as well as increased Bacteroidetes:Firmicutes ratio. Interpretation While H. pylori infection may not be necessarily detrimental in all patients, eradication of H. pylori was associated with widespread changes in gut microbial ecology and structure. Probiotic supplementation could relieve more gastrointestinal symptoms by inducing alterations in gut microbiota and host immune responses. As such, the decision to eradicate H. pylori should be based on comprehensive analysis of individual patients.

Single-layer graphene oxide (SLGO) is emerging as a new-generation membrane material for high-flux, high-selectivity water purification, owing to its favorable two-dimensional morphology that allows facile fabrication of ultrathin membranes with subnanometer interlayer channels. However, reliable and precise molecular sieving performance still necessarily depends on thick graphene oxide (GO) deposition that usually leads to low water flux. This trade-off between selectivity and flux significantly impedes the development of ultrathin GO membranes. In this work, we demonstrate that the selectivity/flux trade-off can be broken by self-assembly of SLGO via simple deposition rate control. We find GO membranes, prepared by slow deposition of SLGO flakes, exhibit considerably improved salt rejection, while counterintuitively having 2.5-4 times higher water flux than that of membranes prepared by fast deposition. This finding has extensive implications of designing/tuning interlayer nanostructure of ultrathin GO membranes by simply controlling SLGO deposition rate and thus may greatly facilitate their development for high flux, high selectivity water purification.

No abstract