Helicobacter pylori infection is the etiology of several gastric-related diseases including gastric cancer. Cytotoxin associated gene A (CagA), vacuolating cytotoxin A (VacA) and α-subunit of urease (UreA) are three major virulence factors of H. pylori, and each of them has a distinct entry pathway and pathogenic mechanism during bacterial infection. H. pylori can shed outer membrane vesicles (OMVs). Therefore, it would be interesting to explore the production kinetics of H. pylori OMVs and its connection with the entry of key virulence factors into host cells. Here, we isolated OMVs from H. pylori 26,695 strain and characterized their properties and interaction kinetics with human gastric adenocarcinoma (AGS) cells. We found that the generation of OMVs and the presence of CagA, VacA and UreA in OMVs were a lasting event throughout different phases of bacterial growth. H. pylori OMVs entered AGS cells mainly through macropinocytosis/phagocytosis. Furthermore, CagA, VacA and UreA could enter AGS cells via OMVs and the treatment with H. pylori OMVs would cause cell death. Comparison of H. pylori 26,695 and clinical strains suggested that the production and characteristics of OMVs are not only limited to laboratory strains commonly in use, but a general phenomenon to most H. pylori strains.

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In this study, the equilibrium conditions for the dissociation of carbon dioxide hydrate in the presence of various additives were examined. To provide new experimental data and discuss the additive effect of cyclic ketones and cyclic alcohols, the equilibrium dissociation temperatures and pressures for carbon dioxide hydrates with the additive of cyclopentanol, cyclohexnol, cycloheptanol, cyclohexanone, or cycloheptanone were measured by an isochoric method. The experimental data were taken at a pressure range of 1.7 to 3.5 MPa and a concentration of 5 wt %. The Clausius–Clapeyron equation was used to speculate the structure of carbon dioxide hydrate with these additives. It was found that the additives of cyclohexanone and cycloheptanone had an inhibitory effect on the formation of carbon dioxide hydrates with the sI structure. Cycloheptanol had a slight inhibitory effect on the formation of carbon dioxide hydrates at lower temperatures, but this effect disappeared at higher temperatures, and this additive also belongs to the sI structure. The addition of cyclopentanol and cyclohexnol additives showed a promotion effect in a low-pressure region on the formation of carbon dioxide hydrates, and the sII hydrate can be produced when adding these two additives.

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