Background
Delayed gastric emptying (DGE) is a frequent complication after pylorus‐preserving pancreatoduodenectomy. Recent studies have suggested that resection of the pylorus is associated with ...decreased rates of DGE. However, superiority of pylorus‐resecting pancreatoduodenectomy was not shown in a recent RCT. This meta‐analysis summarized evidence of the effectiveness and safety of pylorus‐preserving compared with pylorus‐resecting pancreatoduodenectomy.
Methods
RCTs and non‐randomized studies comparing outcomes of pylorus‐preserving and pylorus‐resecting pancreatoduodenectomy were searched systematically in MEDLINE, Web of Science and CENTRAL. Random‐effects meta‐analyses were performed and the results presented as weighted odds ratios (ORs) or mean differences with their corresponding 95 per cent confidence intervals. Subgroup analyses were performed to account for interstudy heterogeneity between RCTs and non‐randomized studies.
Results
Three RCTs and eight non‐randomized studies with a total of 992 patients were included. Quantitative synthesis across all studies showed superiority for pylorus‐resecting pancreatoduodenectomy regarding DGE (OR 2·71, 95 per cent c.i. 1·48 to 4·96; P = 0·001) and length of hospital stay (mean difference 3·26 (95 per cent c.i. −1·04 to 5·48) days; P = 0·004). Subgroup analyses including only RCTs showed no significant statistical differences between the two procedures regarding DGE, and for all other effectiveness and safety measures.
Conclusion
Pylorus‐resecting pancreatoduodenectomy is not superior to pylorus‐preserving pancreatoduodenectomy for reducing DGE or other relevant complications.
No difference
Summary
Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic ...environments. To better understand the emergence of pandemic lineages, it is crucial to discern what differentiates pandemic strains from their environmental relatives. Here, we studied the interaction of environmental V. cholerae with eukaryotic predators or competing bacteria and tested the contributions of the haemolysin and the type VI secretion system (T6SS) to those interactions. Both of these molecular weapons are constitutively active in environmental isolates but subject to tight regulation in the pandemic clade. We showed that several environmental isolates resist amoebal grazing and that this anti‐grazing defense relies on the strains' T6SS and its actincross‐linking domain (ACD)‐containing tip protein. Strains lacking the ACD were unable to defend themselves against grazing amoebae but maintained high levels of T6SS‐dependent interbacterial killing. We explored the latter phenotype through whole‐genome sequencing of 14 isolates, which unveiled a wide array of novel T6SS effector and (orphan) immunity proteins. By combining these in silico predictions with experimental validations, we showed that highly similar but non‐identical immunity proteins were insufficient to provide cross‐immunity among those wild strains.
Over the last few decades humanity has experienced a series of tremendous technological advances, especially in the realm of basic science. A plethora of new approaches has allowed us to appreciate ...life in previously unimaginable detail, prompting the realization that life in the microscopic world is not so different from what we can observe with our naked eyes. Microorganisms, for instance, like any other organism, compete with one another for resources and space. Bacteria often use simple mechanisms to occupy their niche such as rapid growth and biofilm formation. Bacteria also use ingenious strategies to maximize their success. Indeed, to engage in warfare, microorganisms often produce diffusible toxic antimicrobial compounds as well as other more complicated molecular weapons. During this process, effector proteins are delivered, which can intoxicate the target organism. These effectors have different functions but frequently target conserved bacterial or eukaryotic cellular structures such as the cell wall, the membrane compartment, nucleic acids, or the actin cytoskeleton.
Control of laminar-to-turbulent transition on a swept-wing is achieved by base-flow modification in an experimental framework, up to a chord Reynolds number of 2.5 million. This technique is based on ...the control strategy used in the numerical simulation by Dörr & Kloker (J. Phys. D: Appl. Phys., vol. 48, 2015b, 285205). A spanwise uniform body force is introduced using dielectric barrier discharge plasma actuators, to either force against or along the local cross-flow component of the boundary layer. The effect of forcing on the stability of the boundary layer is analysed using a simplified model proposed by Serpieri et al. (J. Fluid Mech., vol. 833, 2017, pp. 164–205). A minimal thickness plasma actuator is fabricated using spray-on techniques and positioned near the leading edge of the swept-wing, while infrared thermography is used to detect and quantify transition location. Results from both the simplified model and experiment indicate that forcing along the local cross-flow component promotes transition while forcing against successfully delays transition. This is the first experimental demonstration of swept-wing transition delay via base-flow modification using plasma actuators.
is a pathogen that causes disease in millions of people every year by colonizing the small intestine and then secreting the potent cholera toxin. How the pathogen overcomes the colonization barrier ...created by the host's natural microbiota is, however, still not well understood. In this context, the type VI secretion system (T6SS) has gained considerable attention given its ability to mediate interbacterial killing. Interestingly, and in contrast to non-pandemic or environmental
isolates, strains that are causing the ongoing cholera pandemic (7PET clade) are considered T6SS-silent under laboratory conditions. Since this idea was recently challenged, we performed a comparative
study on T6SS activity using diverse strains or regulatory mutants. We show that modest T6SS activity is detectable in most of the tested strains under interbacterial competition conditions. The system's activity was also observed through immunodetection of the T6SS tube protein Hcp in culture supernatants, a phenotype that can be masked by the strains' haemagglutinin/protease. We further investigated the low T6SS activity within the bacterial populations by imaging 7PET
at the single-cell level. The micrographs showed the production of the machinery in only a small fraction of cells within the population. This sporadic T6SS production was higher at 30 °C than at 37 °C and occurred independently of the known regulators TfoX and TfoY but was dependent on the VxrAB two-component system. Overall, our work provides new insight into the heterogeneity of T6SS production in populations of 7PET
strains
and provides a possible explanation of the system's low activity in bulk measurements.
Blue natural pigments are rare, especially among plants. However, flowering species that evolved to attract Hymenoptera pollinators are colored by blue anthocyanin-metal complexes. Plants lacking ...anthocyanins are pigmented by betalains but are unable to produce blue hues. By extending the π-system of betalains, we designed a photostable and metal-free blue dye named BeetBlue that did not show toxicity to human hepatic and retinal pigment epithelial cells and does not affect zebrafish embryonal development. This chiral dye can be conveniently synthesized from betalamic acid obtained from hydrolyzed red beetroot juice or by enzymatic oxidation of l-dopa. BeetBlue is blue in the solid form and in solution of acidified polar molecular solvents, including water. Its capacity to dye natural matrices makes BeetBlue the prototype of a new class of low-cost bioinspired chromophores suitable for a myriad of applications requiring a blue hue.
Betalains are phytochemicals of nutraceutical importance that emerged as potent antioxidants, preventing radical chain propagation and the deleterious health effects of oxidative stress. However, ...despite the wide application of betalains as color additives in products for human consumption, little is known about the relationship between their structure and antioxidant potential. Here we investigate the mechanism of antioxidant action of three regioisomeric phenolic betalains and show that the
isomer has higher antiradical capacity than most natural betalains, anthocyanins and flavonoids. Structural and pH effects on redox and antiradical properties were investigated and the results are rationalized in light of quantum chemical calculations. Our results demonstrate that hydrogen atom transfer/proton-coupled electron transfer or sequential proton loss electron transfer mechanisms are plausible to explain the radical chain breaking properties of phenolic betalains in water. Furthermore, mesomeric effects are responsible for the stabilization of the resulting radical phenolic betalains. These findings are useful for the design of biocompatible antioxidants and for the development of novel additives for functional foods and cosmetics with high antioxidant potential.
has caused seven cholera pandemics in the past two centuries. The seventh and ongoing pandemic has been particularly severe on the African continent. Here, we report long read-based genome sequences ...of six
strains isolated in the Democratic Republic of the Congo between 2009 and 2012.
Based on the Monte-Carlo package G
eant4 a new simulation of the complete background spectrum of the HEIDELBERG-MOSCOW experiment which operates five enriched
76
Ge
detectors in a low background ...environment in the Gran Sasso underground laboratory was performed. The resulting background model is used to evaluate the signal of the two neutrino accompanied double beta decay with a statistical significance of
41.57
kg
year
resulting in a half-life of
T
1/2
2ν=(1.74±0.01(stat)
−0.16
+0.18(syst))×10
21 years. Using G
eant4 a simulation of elastic and inelastic neutron reactions has been performed for the first time and is used to estimate the contribution of the neutron flux in the Gran Sasso underground laboratory to the experimental spectrum. The composition of the background in the energy range from 2000 to
2100
keV
around the
Q value for neutrinoless double beta decay is discussed in some detail.
Vibrio cholerae is a well-studied human pathogen that is also a common inhabitant of marine habitats. In both environments, the bacterium is subject to interbacterial competition. A molecular ...nanomachine that is often involved in such competitive behavior is the type VI secretion system (T6SS). Interestingly and in contrast to non-pandemic or environmental isolates, the T6SS of the O1 El Tor clade of V. cholerae, which is responsible for the ongoing 7th cholera pandemic, is largely silent under standard laboratory culture conditions. Instead, these strains induce their full T6SS capacity only under specific conditions such as growth on chitinous surfaces (signaled through TfoX and QstR) or when the cells encounter low intracellular c-di-GMP levels (TfoY-driven). In this study, we identified a single nucleotide polymorphism (SNP) within an intergenic region of the major T6SS gene cluster of V. cholerae that determines the T6SS status of the cell. We show that SNP conversion is sufficient to induce T6SS production in numerous pandemic strains, while the converse approach renders non-pandemic/environmental V. cholerae strains T6SS-silent. We further demonstrate that SNP-dependent T6SS production occurs independently of the known T6SS regulators TfoX, QstR, and TfoY. Finally, we identify a putative promoter region adjacent to the identified SNP that is required for all forms of T6SS regulation in V. cholerae.
PDF
