Most studies on Salmonella enterica serovar Typhimurium infection focus on strains ATCC SL1344 or NTCC 12023 (ATCC 14028). We have compared the abilities of these strains to induce membrane ruffles and invade epithelial cells. S. Typhimurium strain 12023 is less invasive and induces smaller membrane ruffles on MDCK cells compared with SL1344. Since the SPI-1 effector SopE is present in SL1344 and absent from 12023, and SL1344 sopE mutants have reduced invasiveness, we investigated whether 12023 is less invasive due to the absence of SopE. However, comparison of SopE+ and SopE− S. Typhimurium strains, sopE deletion mutants and 12023 expressing a sopE plasmid revealed no consistent relationship between SopE status and relative invasiveness. Nevertheless, absence of SopE was closely correlated with reduced size of membrane ruffles. A PprgH–gfp reporter revealed that relatively few of the 12023 population (and that of the equivalent strain ATCC 14028) express SPI-1 compared to other S. Typhimurium strains. Expression of a PhilA–gfp reporter mirrored that of PprgH–gfp in 12023 and SL1344, implicating reduced signalling via the transcription factor HilA in the heterogeneous SPI-1 expression of these strains. The previously unrecognized strain heterogeneity in SPI-1 expression and invasiveness has important implications for studies of Salmonella infection.

Background Electronic cigarettes (e-cigarettes) have been characterised as significantly less harmful than cigarettes by many health agencies and regulators globally. In this study, we examined to what extent perceived relative harms of e-cigarettes compared to cigarettes have changed in the USA. Methods We analysed the data from the longitudinal and nationally representative, Population Assessment of Tobacco and Health Study to assess the relative perceived harm of e-cigarettes amongst US adults between 2013 and 2016. Results The proportion of US adults who correctly perceived e-cigarettes as less harmful than cigarettes decreased each year from 41.1% (CI 40.1–42.1%) in 2013–2014, 31.5% (CI 30.8–32.2%) in 2014–2015 and 25.3% (CI 24.6–26.0%) in 2015–2016. Concurrently, the proportion of US adults who perceived e-cigarettes as equally, or more, harmful than cigarettes increased from 53.7% (CI 52.3–55.1%), 64.9% (CI 63.6–66.2%) to 72.7% (CI 71.5–73.9%) respectively. The proportion of US adults who held negative relative harm perceptions of e-cigarettes increased regardless of current smoking or vaping status by 24.6% and 29.6% respectively within 3 years. In Wave 3, the proportion of current smokers who perceived the relative harm of e-cigarettes as less harmful was lower at 29.3% (CI 28.2–30.4%) compared to current e-cigarette users at 43.5% (CI 40.3–46.7%). Former smokers who used e-cigarettes and believed that they were equally, or more, harmful than cigarettes in 2014–2015 had significantly higher rates of smoking relapse in the following year, 29% and 37% (p < 2.2e−16), respectively, compared to those with positive relative harm perceptions who reported relapse rates of 19%. Conclusions In this study, the proportion of US adults who incorrectly perceived e-cigarettes as equal to, or more, harmful than cigarettes increased steadily regardless of smoking or vaping status. Current adult smokers appear to be poorly informed about the relative risks of e-cigarettes yet have potentially the most to gain from transitioning to these products. The findings of this study emphasise the urgent need to accurately communicate the reduced relative risk of e-cigarettes compared to continued cigarette smoking and clearly differentiate absolute and relative harms. Further research is required to elucidate why the relative harm of e-cigarettes is misunderstood and continues to deteriorate.

SPAN(®) 80 can control the particle size and lung distribution of agar beads and P. aeruginosa-embedded beads prepared with 0.01%v/v SPAN(®)80 can induce infection and inflammation over 7 days.

Heated tobacco products represent a novel category of tobacco products in which a tobacco consumable is heated to a temperature that releases nicotine from the tobacco leaf but not to a temperature sufficient to cause combustion. Heated tobacco products may therefore have the potential to be a less harmful alternative for adult smokers that would otherwise continue to smoke conventional cigarettes. Given the rapid development of this product category, the aim of this review was to examine the available peer-reviewed scientific evidence related to heated tobacco products and highlight any research gaps. In recent years, manufacturers of heated tobacco products have published a number of studies on their respective heated tobacco products. Whilst there is limited research that is independent of commercial interests, the available scientific evidence indicates that heated tobacco products produce a much simpler aerosol than conventional cigarette smoke, with fewer and substantially lower levels of harmful toxicants. Toxicology assessments indicate these reductions in aerosol toxicants translate to reduced biological effects. Biomarker and clinical data from studies in which product use is controlled within a clinical setting, indicate changes in biomarker levels and clinical end-points similar to observations in cessation studies, indicating the potential for reduced harm. The scientific evidence also indicates that exposure of non-users to emissions from heated tobacco products in indoor environments is significantly reduced compared to exposure resulting from smoking conventional cigarettes. Overall, the available scientific evidence indicates that heated tobacco products hold promise as a less harmful alternative to conventional cigarettes, but more independent data is required to validate industry findings. As a growing product category, epidemiological studies and independent population modelling studies are outstanding, and empirical data on how dual tobacco product category use by consumers affects their risk profile is lacking.

Encouraging adult smokers who are uninterested or unwilling to quit, and would otherwise continue to smoke, to transition to potentially less harmful nicotine products such as electronic nicotine delivery systems (ENDS) may positively impact population health. However, counterbalancing this benefit is the societal concern that ENDS may be used by never smokers and youth and serve as a ‘gateway’ into cigarette smoking. Data were analysed from two independent surveys of the prevalence and perceptions of myblu ENDS use in the United States. Total sample size was 22,232 young adults and 23,264 adults. Being curious to use myblu was 1.6–2.0 times more likely in young adult current smokers than young adult never smokers. This likelihood was 2.8 times greater for adult current smokers compared with adult never smokers in the perceptions survey, while in the prevalence survey, there was no difference between adult current and never smokers. Intentions to use myblu were significantly greater in young adult current smokers compared with young adult never smokers in both surveys and in adults in the prevalence survey. In all surveys and age cohorts, 124 of 45,496 participants (0.1% of the total survey population) reported first using myblu prior to smoking cigarettes and went on to become established smokers. Curiosity and intentions to use myblu were generally higher in current smokers compared with never smokers. There was minimal evidence to suggest the existence of a ‘gateway’ effect to established cigarette smoking among never‐smoking myblu users.