A novel infective endocarditis virulence factor related to multiple functions for bacterial survival in blood was discovered in Streptococcus sanguinis.

We identified the role of a conserved hypothetical protein (SSA_0451) in S. sanguinis that is involved in the virulence of infective endocarditis. An in vitro whole blood killing assay and rabbit endocarditis model studies revealed that the SSA_0451 mutant (ΔSSA_0451) was significantly less virulent than the wild-type (SK36) and its complementation mutant (ΔSSA_0451C). The mechanism underlying the SSA_0451 mutant's reduced virulence in infective endocarditis was evidentially linked to oxidative stress and environmental stress. The genes related to the survival of S. sanguinis in an oxidative stress environment were downregulated in ΔSSA_0451, which affected its survival in blood. Our findings suggest that SSA_0451 is a novel IE virulence factor and a new target for drug discovery against IE.

Experimental evolution of gene essentiality in bacteria.

Essential gene products carry out fundamental cellular activities in interaction with other components. However, the lack of essential gene mutants and appropriate methodologies to link essential gene functions with their partners poses significant challenges. Here, we have generated deletion mutants in 32 genes previously identified as essential, with 23 mutants showing extremely slow growth in the SK36 strain of Streptococcus sanguinis . Whole-genome sequencing of 243 independently evolved populations of these mutants has identified >1000 spontaneous suppressor mutations in experimental evolution, many of which are new gene and pathway relationships, such as F1Fo-ATPase/V1V1-ATPase/TrkA1-H1 gene pathway. Patterns of spontaneous mutations occurring in essential gene mutants differed from those found in wildtype. While gene duplications occurred rarely, substitutions, deletions, and insertions were prevalent in evolved populations. These essential gene deletion mutants and spontaneous mutations fixed in the mutant populations during evolution established a foundation for understanding gene essentiality and the interaction of essential genes in networks.

Uncertainty stress and self-rated health during the early stage of the COVID-19 outbreak.

Objectives: The COVID-19 crisis caused unparalleled uncertainty stress and health-related symptoms among Chinese residents. This study aimed to characterize stress status during the early stage of the pandemic and explore the inner mechanism between uncertainty stress and self-rated health. Setting/participants: A cross-sectional design was conducted online from February 7 to 14, 2020. A total of 2534 Chinese participants were surveyed. Main outcome measures: Uncertainty stress, negative affect, sleep quality, and health status were measured by self-report. A sequential mediation model using bootstrapping method was applied to test these relationships. Results: Age, place of residence, marital status, occupation, household annual income, infection, and quarantine status significantly correlated with uncertainty stress. Higher uncertainty stress was negatively related with self-rated health (r = -0.256, p < 0.01) and positively associated with higher negative emotions (r = 0.646, p < 0.01). The sequential mediation model found total indirect effect (ß = -0.014, 95%C.I. = -0.017-0.010) and direct effect (ß = -0.010, 95%C.I. = -0.015-0.005) were significant in the relationship between uncertainty stress and self-rated health with mediating by negative affect and subjective sleep quality. Conclusions: Findings provided evidence-based information for stakeholders designing and implementing intervention strategies by providing psychological consultation services and public education to manage uncertainty stress and minimize the damage of negative affect and poor sleep.

Tobacco Advertising, Anti-Tobacco Information Exposure, Environmental Smoking Restrictions, and Unassisted Smoking Cessation Among Chinese Male Smokers: A Population-Based Study.

The study examined the prevalence of unassisted smoking cessation among Chinese urban male smokers and factors important in the decision to quit. A cross-sectional survey employing multistage sampling involving 5,782 participants in six cities in China was conducted. Survey respondents reported their smoking cessation status and related individual and environmental variables. Among current smokers 1,112 or 35.0% (95% CI [31.0%, 40.8%]) had attempted to quit and of those who had made such an attempt 87.6% reported that they had done so without assistance. Of all former smokers (3,389), most (97.6%; 95% CI [96.7%, 98.5%]) quit without assistance. Logistic regression analysis showed those who engaged in physical exercise and who had more belief in their ability to quit were more than twice as likely to make a quit attempt and be successful than those in comparable reference groups. Exposure to tobacco advertising was negatively associated with both unassisted quit attempts and success. By contrast, exposure to anti-tobacco information was positively associated with unassisted quit attempts while household and workplace smoking restrictions were negatively associated with unassisted attempts to quit. Most attempts to quit smoking among Chinese males are unassisted. Unassisted attempts to quit smoking and success rates are highly influenced by the presence of environmental smoking restrictions, tobacco advertising, and exposure to anti-tobacco information. Smoking cessation programs and policies in China need to pay greater attention to the social and cultural norms, which perpetuate high levels of smoking.

Iron Oxide Nanowire-Based Filter for Inactivation of Airborne Bacteria.

Heating, ventilation, and air conditioning (HVAC) systems are among the most common methods to improve indoor air quality. However, after long-term operation, the HVAC filter can result in a proliferation of bacteria, which may release into the filtered air subsequently. This issue can be addressed by designing antibacterial filters. In this study, we report an iron oxide nanowires-based filter fabricated from commercially available iron mesh through a thermal treatment. At optimal conditions, the filter demonstrated a log inactivation efficiency of > 7 within 10 seconds towards S. epidermidis (Gram-positive), a common bacterial species of indoor bioaerosol. 52 % of bioaerosol cells can be captured by a single filter, which can be further improved to 98.7 % by connecting five filters in-tandem. The capture and inactivation capacity of the reported filter did not degrade over long-term use. The inactivation of bacteria is attributed to the synergic effects of the hydroxyl radicals, electroporation, and Joule heating, which disrupted the cell wall and nucleoid of S. epidermidis, as verified by the model simulations, fluorescence microscopy, electron microscopy, and infrared spectroscopy. The relative humidity plays an important role in the inactivation process. The filter also exhibited a satisfactory inactivation efficiency towards E. coli (Gram-negative). The robust synthesis, low cost, and satisfactory inactivation performance towards both Gram-positive and Gram-negative bacteria make the filter demonstrated here suitable to be assembled into HVAC filters as an antibacterial layer for efficient control of indoor bioaerosols.

TNFSF4 gene polymorphism rs3861950 but not rs3850641 is associated with the risk of cerebral infarction in a Chinese population.

Tumor necrosis factor superfamily member 4 (TNFSF4) plays a key role in the process of atherosclerosis, a common risk factor for both myocardial and cerebral infarctions. Recent studies indicate that the single nucleotide polymorphism (SNP) rs3850641 in TNFSF4 is associated with higher risk of myocardial infarction, but little is known about the association between TNFSF4 variation and cerebral infarction (CI). A case-control study involving 385 CI patients and 385 age-matched, sex-matched non-CI controls was conducted in a Chinese population, only the most common subtype, atherosclerosis CI, was recruited. Two SNPs of TNFSF4, rs3850641 and rs3861950, were genotyped by the TaqMan SNP genotyping method, and verified partly by genomic DNA sequencing. The results revealed a significant allelic association between rs3861950 and CI (Odds ration = 1.733, 95 % confidence interval = 1.333-2.254, P = 0.000). Genotypic association analysis demonstrated that the CC genotype of rs3861950 confers susceptibility to CI (Odds ration = 2.896, 95 % confidence interval = 1.368-6.132), and it was associated with a significantly higher risk of ischemic stroke (Odds ration = 3.520, 95 % confidence interval = 1.546-8.015, P = 0.003) after adjusting for the other confirmed risk factors such as the history of hypertension, diabetes, CAD, smoking and alcohol drinking. While the odds ratio of the T allele to the C allele was 1.733 (95 % confidence interval: 1.333-2.254). However, there was no significant association between rs3850641 and CI (Odds ration = 1.288, 95 % confidence interval = 0.993-1.670, P = 0.056). TNFSF4 gene polymorphism rs3861950, but not rs3850641, is associated with the risk of atherosclerosis CI in a Chinese population.