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Abstract Antibiotic resistance is a global healthcare crisis. Bacteria are highly adaptable and can rapidly acquire mechanisms of resistance towards conventional antibiotics. The permeability barrier conferred by the Gram-negative bacteria cell envelope constitutes a first line of defence against the action of antibiotics. Exposure to extracytoplasmic stresses can negatively affect cell envelope homoeostasis and this causes localised protein misfolding, compromised envelope integrity and impairs barrier function. The CpxA-CpxR two-component regulatory system has evolved to sense extracytoplasmic stresses and to regulate processes that restore homoeostasis of the cell envelope. Hence, controlled Cpx-signalling assists bacteria in adapting, surviving and proliferating in harsh environments, including exposure to antibiotics. Herein, we determined that an intact Cpx-signalling is key to maintaining the Yersinia pseudotuberculosis resistance to colistin and polymyxin B. The susceptibility displayed by Cpx-signalling defective mutants, correlated with cell-envelope deformity and specific modifications of Lipid-A. In vivo transcriptional analysis and in vitro protein-DNA binding studies demonstrated that these modifications were dependent on the direct regulation of Lipid-A biogenesis and modifications of operons by the active phosphorylated CpxR~P isoform. Altogether, our work defines the regulatory mechanism that enables Cpx-signalling to actively control cell envelope remodelling and the permeability of antibiotics in the clinically relevant enteropathogen Y. pseudotuberculosis.

Abstract Many bacterial immune systems recognize phage structural components to activate antiviral responses, without inhibiting the function of the phage component. These systems can be encoded in specific chromosomal loci, known as defense islands, and in mobile genetic elements such as prophages and phage-inducible chromosomal islands (PICIs). Here, we identify a family of bacterial immune systems, named Tai (for ‘tail assembly inhibition’), that is prevalent in PICIs, prophages and P4-like phage satellites. Tai systems protect their bacterial host population from other phages by blocking the tail assembly step, leading to the release of tailless phages incapable of infecting new hosts. To prevent autoimmunity, some Tai-positive phages have an associated counter-defense mechanism that is expressed during the phage lytic cycle and allows for tail formation. Interestingly, the Tai defense and counter-defense genes are organized in a non-contiguous operon, enabling their coordinated expression.

Despite constant development of surgical implants, instruments, and rehabilitation protocols, the outcomes of anterior cruciate ligament reconstruction remain unpredictable, and the failure rate of isolated procedures remains unacceptably high. Several factors possibly concerning suboptimal outcomes and risk of graft rerupture have been highlighted, among which are graft healing, tunnel position, and residual rotational instability. Recent studies have suggested that addressing anterolateral complex injury and enhancing graft healing properties might improve the outcomes of surgery. We propose a simple technique of combined anterior cruciate ligament and anterolateral ligament reconstruction using pedicled semitendinosus and gracilis tendons with a single femoral tunnel and no additional tibial tunnels.

Macrophages are crucial immune cells that play a role in tissue repair and can exhibit pro- or anti-inflammatory behaviour based on environmental stimulation. Their functional phenotype can be affected by platelet-derived products as determined by those products’ composition. When the inflammatory response caused by implantation is excessive, it can lead to rejection of the implant. Therefore, a thorough evaluation of implant haemocompatibility is necessary to minimise undesirable consequences.

We report the case of a 3-year-old girl who was admitted to the hospital because she had been passing tarry stools for about a month. Passing black, tarry stools is a distressing symptom and usually the result of gastrointestinal (GI) bleeding. Injury due to an ingested foreign body may be one of the causes of GI bleeding. The increasing popularity of magnetic toys in recent decades has raised the incidence of magnet ingestion in the pediatric population. Injuries caused by these objects carry a significant and potentially preventable risk of morbidity and even mortality in children. The clinical picture is variable and may include non-specific symptoms such as GI bleeding. It is important for pediatricians to consider the possibility of a foreign body in the GI tract in the diagnosis of GI bleeding and spread awareness about the danger of objects containing magnets.

Nowadays, ammonia is viewed as the prospective green hydrogen fuel carrier. Yet, there still is a demand for active, energy-efficient NH3 synthesis catalysts to make ammonia use economically viable. This paper studies and discusses lanthanide oxide-supported cobalt catalysts for low-pressure ammonia synthesis, which are intended to be a model for prototyping systems alternative to ruthenium-based catalysts. In the Co/Ln2O3 system, lanthanide oxide is a support and an electronic promoter. The electron density on the active phase’s surface is increased through Strong Metal-Support Interactions and the formation of oxygen-deficient, Ln2O3−x species capable of electron donation. In the systems, electronic promotion strength depends on the Ln3+ cation and the support conductivity, catalyst Turnover Frequency and basicity increase exponentially with the increase of the Ln3+ ionic radius. These dependencies enable the design of novel cobalt catalysts of specific properties and outline the prospects for their further development.

ABSTRACTBacterial conjugation, a process of horizontal gene transfer, plays a key role in promoting the spread of antimicrobial resistance among human pathogens. The mechanism of conjugation involves the development of a conjugative pilus that forms a physical bridge between two bacterial cells and the subsequent unidirectional transfer of single-stranded DNA (ssDNA) complexed with a protein from the donor to the recipient cell. Atomic structures exist for many of the components of the type IV secretion system (T4SS), responsible for the nucleoprotein secretion, but little is known about the events preceding gene transfer, specifically what is the extent of the participation of the conjugative pilus in ssDNA transfer? There has been a longstanding debate about whether its main role is to bring a donor and a recipient cell into physical juxtaposition and form a mating junction that allows for ssDNA transfer via the T4SS machinery complex or whether ssDNA is actually transferred through the lumen of the pilus. Here, through a combination of maleimide labeling of the conjugative pilus and SeqA-YFP labeling of the transferred ssDNA, we visualize the process of bacterial conjugation in real time. We discover that the conjugative pilus is capable of transferring the ssDNA at a distance, between physically separated cells, and thus conclude that a physical mating junction is not essential for conjugative gene transfer.IMPORTANCEBacteria are constantly exchanging DNA, which constitutes horizontal gene transfer. While some of these occurs by a non-specific process called natural transformation, some occurs by a specific mating between a donor and a recipient cell. In specific conjugation, the mating pilus is extended from the donor cell to make contact with the recipient cell, but whether DNA is actually transferred through this pilus or by another mechanism involving the type IV secretion system complex without the pilus has been an open question. Using Escherichia coli, we show that DNA can be transferred through this pilus between a donor and a recipient cell that has not established a tight mating junction, providing a new picture for the role of this pilus.

Enteropathogenic bacteria use extracellular appendages, known as F-pili, to share plasmids carrying antibiotic resistance genes. Here, the authors show that F-pili are highly flexible but robust at the same time, and this is important for plasmid transfer and formation of biofilms that protect against the action of antibiotics.

BackgroundEsophageal atresia (EA) is a rare congenital anomaly characterized by a discontinuity of the esophagus. Following surgical repair, survival rates have improved dramatically the past decenniums and today exceed 90%, but the children commonly present with esophageal and respiratory morbidity. In 2018, a condition-specific quality-of-life questionnaire for children with esophageal atresia (EA) aged 2–7 in Sweden-Germany was finalized (The EA-QOL questionnaire). The study aim was to describe the evaluation of the new translations across 12 new countries in Europe, Asia, Africa, Central-and North America.MethodsFollowing forward-backward translation into the new languages, the 17-item EA-QOL questionnaire was tested in cognitive debriefing interviews with parents of children with EA aged 2–7. Parents rated if each item was easy to understand (clarity) and sensitive to answer (interference with personal integrity). They could skip responding to a non-applicable/problematic item and give open comments. Predefined psychometric criteria were used; item clarity ≥80%/item sensitive to answer ≤20%/item feasibility ≤5% missing item responses. The decision to modify the translation was based on native expert, patient stakeholder, and instrument developer review, and the need for harmonization between translations.ResultsSimilar to findings in the Swedish-German cognitive debriefing, the cross-cultural analysis of input from 116 parents from 12 new countries (4–14 parents, median 9 parents/country) showed that all items in the EA-QOL questionnaire fulfilled the criteria for item clarity ≥80% and sensitive to answer (ranging from 1%-4.5%), although results varied between countries. Four items had missing responses between 5.2% and 13.4%, three within the same domain and were in line with parents’ explanations. Poor translations and feasibility were improved.ConclusionsBased on parent input, the collaboration between native experts, patient stakeholders, and instrument developers, a linguistic version of the EA-QOL questionnaire for children aged 2–7 for use in and across 14 countries has been established. These efforts have set the conditions for a cross-cultural field test of the EA-QOL questionnaire and will open the doors for a new chapter in outcome research, registries, and clinical practice concerning children with EA. In the long-term, this will help increase knowledge of the disease's burden, promote patient-centeredness, exchange of information between nations, and strengthen evidence-based treatments for children born with EA.

Abstract Background Despite inconsistent evidence, international guidelines underline the importance of perioperative hyperoxygenation in prevention of postoperative infections. Further, data on safety and efficacy of this method in liver transplant setting are lacking. The aim was to evaluate efficacy and safety of postoperative hyperoxygenation in prophylaxis of infections after liver transplantation. Methods In this randomized controlled trial, patients undergoing liver transplantation were randomly assigned to either 28% or 80% fraction of inspired oxygen (FiO2) for 6 postoperative hours. Infections occurring during 30-day post-transplant period were the primary outcome measure. Secondary outcome measures included 90-day mortality, 90-day severe morbidity, 30-day pulmonary complications, durations of hospital and intensive care unit stay, and 5-day postoperative bilirubin concentration, alanine and aspartate transaminase activity, and international normalized ratio (INR) (clinicatrials.gov NCT02857855). Results A total of 193 patients were included and randomized to 28% (n = 99) and 80% (n = 94) FiO2. With similar patient, operative, and donor characteristics in both groups, infections occurred in 34.0% (32/94) of patients assigned to 80% FiO2 as compared to 23.2% (23/99) of patients assigned to 28% FiO2 (p = 0.112). Patients randomized to 80% FiO2 more frequently developed severe complications (p = 0.035), stayed longer in the intensive care unit (p = 0.033), and had higher bilirubin concentration over first 5 post-transplant days (p = 0.043). No significant differences were found regarding mortality, duration of hospital stay, pulmonary complications, and 5-day aspartate and alanine transaminase activity and INR. Conclusions Postoperative hyperoxygenation should not be used for prophylaxis of infections after liver transplantation due to the lack of efficacy. Trial registration ClinicalTrials.gov NCT02857855. Registered 7 July 2016.

Bacteria can exchange DNA through extracellular appendages (‘mating pili’) in a process known as conjugation. Here, Beltran et al. determine atomic structures by cryo-electron microscopy of a bacterial conjugative pilus and two archaeal pili, showing that the archaeal pili are homologous to bacterial mating pili.