Characterization of natural product inhibitors of quorum sensing in Pseudomonas aeruginosa reveals competitive inhibition of RhlR by ortho-vanillin.

Quorum sensing (QS) is a cell-cell signaling system that enables bacteria to coordinate population density-dependent changes in behavior. This chemical communication pathway is mediated by diffusible N-acyl L-homoserine lactone signals and cytoplasmic signal-responsive LuxR-type receptors in Gram-negative bacteria. As many common pathogenic bacteria use QS to regulate virulence, there is significant interest in disrupting QS as a potential therapeutic strategy. Prior studies have implicated the natural products salicylic acid, cinnamaldehyde and other related benzaldehyde derivatives as inhibitors of QS in the opportunistic pathogen Pseudomonas aeruginosa, yet we lack an understanding of the mechanisms by which these compounds function. Herein, we evaluate the activity of a set of benzaldehyde derivatives using heterologous reporters of the P. aeruginosa LasR and RhlR QS signal receptors. We find that most tested benzaldehyde derivatives can antagonize LasR or RhlR reporter activation at micromolar concentrations, although certain molecules also caused mild growth defects and nonspecific reporter antagonism. Notably, several compounds showed promising RhlR or LasR specific inhibitory activities over a range of concentrations below that causing toxicity. Ortho-Vanillin, a previously untested compound, was the most promising within this set. Competition experiments against the native ligands for LasR and RhlR revealed that ortho-vanillin can interact competitively with RhlR but not with LasR. Overall, these studies expand our understanding of benzaldehyde activities in the LasR and RhlR receptors and reveal potentially promising effects of ortho-vanillin as a small molecule QS modulator against RhlR.

Damage Control Laparotomy and Management of the Open Abdomen.

Management of the open abdomen has been used for decades by general surgeons. Techniques have evolved over those decades to improve control of infection, fluid loss, and improve the ability to close the abdomen to avoid hernia formation. The authors explore the history, indications, and techniques of open abdomen management in multiple settings. The most important considerations in open abdomen management include the reason for leaving the abdomen open, prevention and mitigation of ongoing organ dysfunction, and eventual plans for abdominal closure.

Changes in an enzyme ensemble during catalysis observed by high-resolution XFEL crystallography.

Enzymes populate ensembles of structures necessary for catalysis that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography at an x-ray free electron laser to observe catalysis in a designed mutant isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations, and formation of the thioimidate intermediate selects for catalytically competent substates. The influence of cysteine ionization on the ICH ensemble is validated by determining structures of the enzyme at multiple pH values. Large molecular dynamics simulations in crystallo and time-resolved electron density maps show that Asp17 ionizes during catalysis and causes conformational changes that propagate across the dimer, permitting water to enter the active site for intermediate hydrolysis. ICH exhibits a tight coupling between ionization of active site residues and catalysis-activated protein motions, exemplifying a mechanism of electrostatic control of enzyme dynamics.

Quantifying the effects of exceptional fossil preservation on the global availability of phylogenetic data in deep time.

Fossil deposits with exceptional preservation ("lagerstätten") provide important details not typically preserved in the fossil record, such that they hold an outsized influence on our understanding of biodiversity and evolution. In particular, the potential bias imparted by this so-called "lagerstätten effect" remains a critical, but underexplored aspect of reconstructing evolutionary relationships. Here, we quantify the amount of phylogenetic information available in the global fossil records of 1,327 species of non-avian theropod dinosaurs, Mesozoic birds, and fossil squamates (e.g., lizards, snakes, mosasaurs), and then compare the influence of lagerstätten deposits on phylogenetic information content and taxon selection in phylogenetic analyses to other fossil-bearing deposits. We find that groups that preserve a high amount of phylogenetic information in their global fossil record (e.g., non-avian theropods) are less vulnerable to a "lagerstätten effect" that leads to disproportionate representation of fossil taxa from one geologic unit in an evolutionary tree. Additionally, for each taxonomic group, we find comparable amounts of phylogenetic information in lagerstätten deposits, even though corresponding morphological character datasets vary greatly. Finally, we unexpectedly find that ancient sand dune deposits of the Late Cretaceous Gobi Desert of Mongolia and China exert an anomalously large influence on the phylogenetic information available in the squamate fossil record, suggesting a "lagerstätten effect" can be present in units not traditionally considered lagerstätten. These results offer a phylogenetics-based lens through which to examine the effects of exceptional fossil preservation on biological patterns through time and space, and invites further quantification of evolutionary information in the rock record.

Disparities in funding for Nobel Prize awards in medicine and physiology across nationalities, races, and gender.

Since 1901, the Nobel Prize in Physiology and Medicine has been awarded to numerous individuals for their outstanding contributions. This article presents a comprehensive analysis of the Nobel Prize recipients, focusing on gender, race, and nationality. We observe that an alarming disparity emerges when we examine the underrepresentation of Black scientists among Nobel laureates. Furthermore, trends in nationalities show how Americans make up the majority of Nobel Prize winners, while there is a noticeable lack of gender and racial minority winners of the Nobel Prize in Physiology and Medicine. Together, this highlights the importance of diversity and inclusion in scientific achievement. We offer suggestions and techniques, including funding opportunities and expanding nominators, to improve the gender, racial, and geographical diversity of Nobel Prizes.

D-ß-hydroxybutyrate stabilizes hippocampal CA3-CA1 circuit during acute insulin resistance.

1.The brain primarily relies on glycolysis for mitochondrial respiration but switches to alternative fuels such as ketone bodies (KBs) when less glucose is available. Neuronal KB uptake, which does not rely on glucose transporter 4 (GLUT4) or insulin, has shown promising clinical applicability in alleviating the neurological and cognitive effects of disorders with hypometabolic components. However, the specific mechanisms by which such interventions affect neuronal functions are poorly understood. In this study, we pharmacologically blocked GLUT4 to investigate the effects of exogenous KB D-P-hydroxybutyrate (D-ßHb) on mouse brain metabolism during acute insulin resistance (AIR). We found that both AIR and D-ßHb had distinct impacts across neuronal compartments: AIR decreased synaptic activity and long-term potentiation (LTP) and impaired axonal conduction, synchronization, and action potential (AP) properties, while D- PHb rescued neuronal functions associated with axonal conduction, synchronization and LTP.

History in the pub: The historiography of J.D. Wetherspoon.

J. D. Wetherspoon is a popular pub chain in the United Kingdom. Despite its prominence in British cultural life and active and deliberate engagement with history, it has received scant academic attention. Here, this engagement with history is explored with a particular focus on how Wetherspoon approaches the history of science. This paper highlights the focus of Wetherspoon on local history and, in particular, on local exceptionalism, before discussing how such an understanding of history informs wider debates-such as Wetherspoon's support of Brexit (the UK's withdrawal from the European Union). It contributes to understandings of what constitutes popular history and, through doing so, emphasises the need for historians to engage with historical narratives outside the academy.

Global patterns of plumage color evolution in island-living passeriform birds.

Island environments have the potential to change evolutionary trajectories of morphological traits in species relative to their mainland counterparts due to habitat and resource differences, or by reductions in the intensity of social or sexual selection. Latitude, island size, and isolation may further influence trait evolution through biases in colonization rates. We used a global dataset of passerine plumage color as a model group to identify selective pressures driving morphological evolution of island animals using phylogenetically-controlled analyses. We calculated chromaticity values from red and blue scores extracted from images of the majority of Passeriformes and tested these against the factors hypothesized to influence color evolution. In contrast to predictions based on sexual and social selection theory, we found consistent changes in island female color (lower red and higher blue chromaticity), but no change in males. Instead, island size and distance from mainland and other islands influenced color in both sexes, reinforcing the importance of island physiognomy in shaping evolutionary processes. Interactions between ecological factors and latitude also consistently influenced color for both sexes, supporting a latitudinal gradient hypothesis. Finally, patterns of color evolution varied among families, indicating taxon-specific microevolutionary processes in driving color evolution. Our results show island residency influences color evolution differently between sexes, but the patterns in both sexes are tempered by ecological, island characteristics, and phylogenetic effects that further vary in their importance among families. The key role of environmental factors in shaping bird plumage on islands further suggests a reduced importance of sexual and social factors in driving color evolution.

MitoTracker: A useful tool in need of better alternatives.

The fluorescence viewing of mitochondria is commonly performed by MitoTracker, a lipophilic cationic dye that is taken up by the mitochondria. In this forum, we highlight several issues that may occur with MitoTracker, including staining of other organelles. Our aim is to offer alternative dyes and discuss their advantages and disadvantages. We also offer options for software with alternatives to MitoTracker to expedite future experimental design.

X-ray-driven chemistry and conformational heterogeneity in atomic resolution crystal structures of bacterial dihydrofolate reductases.

Dihydrofolate reductase (DHFR) catalyzes the NADPH-dependent reduction of dihydrofolate to tetrahydrofolate. Bacterial DHFRs are targets of several important antibiotics as well as model enzymes for the role of protein conformational dynamics in enzyme catalysis. We collected 0.93 Å resolution X-ray diffraction data from both Bacillus subtilis (Bs) and E. coli (Ec) DHFRs bound to folate and NADP+. These oxidized ternary complexes should not be able to perform chemistry, however electron density maps suggest hydride transfer is occurring in both enzymes. Comparison of low- and high-dose EcDHFR datasets show that X-rays drive partial production of tetrahydrofolate. Hydride transfer causes the nicotinamide moiety of NADP+ to move towards the folate as well as correlated shifts in nearby residues. Higher radiation dose also changes the conformational heterogeneity of Met20 in EcDHFR, supporting a solvent gating role during catalysis. BsDHFR has a different pattern of conformational heterogeneity and an unexpected disulfide bond, illustrating important differences between bacterial DHFRs. This work demonstrates that X-rays can drive hydride transfer similar to the native DHFR reaction and that X-ray photoreduction can be used to interrogate catalytically relevant enzyme dynamics in favorable cases.

Development of the ARENA training programme for resilient performance in defense and security settings.

Defense and Security Personnel (DSP) often have to operate in the presence of stressful demands. Prior research has identified factors and processes associated with DSP being able to perform resiliently in demanding situations and settings. The aim of the present study was to develop a resilient performance training programme for UK defense and security operators. An intervention mapping (IM) method was used to guide the development of the programme. Typically, IM follows six sequential phases. In the present work, these phases were shaped by insights from prior research (e.g. systematic review and end user interviews), the input of a dedicated working group (N = 13) and from practitioner focus groups. During the IM process, the importance of programme flexibility was emphasized by practitioners. As such, the enAbling REsilieNt performAnce (ARENA) training programme was designed to be agile and include both face-to-face training and online learning modules. Theoretical behavior change principles, closely aligned to findings of earlier work on resilient defense and security performance, were used to underpin programme content and delivery. Future research should seek to gather data on the impact of the ARENA programme, in the targeted biological, psychological and social factors that previously been associated with resilient performances.

Diversity, Equity and Inclusion in the Laboratory: Strategies to Enhance Inclusive Laboratory Culture.

Building a diverse laboratory that is equitable is critical for the retention of talent and the growth of trainees professionally and personally. Here, we outline several strategies including enhancing understanding of cultural competency and humility, establishing laboratory values, and developing equitable laboratory structures to create an inclusive laboratory environment to enable trainees to achieve their highest success.

The effect of acute exercise on objectively measured sleep and cognition in older adults.

Background: Exercise can improve cognition in aging, however it is unclear how exercise influences cognition, and sleep may partially explain this association. The current study aimed to investigate whether objectively measured sleep mediates the effect of an acute exercise intervention on cognition in older adults. Methods: Participants were 30 cognitively unimpaired, physically active older adults (69.2 ± 4.3 years) with poor sleep (determined via self-report). After a triple baseline cognitive assessment to account for any natural fluctuation in cognitive performance, participants completed either a single bout of 20-minutes of high intensity exercise on a cycle ergometer, or a control condition, in a cross-over trial design. Cognition was measured immediately post-intervention and the following day, and sleep (total sleep time, sleep onset latency, sleep efficiency, % of rapid eye movement sleep, light sleep and deep sleep) was characterized using WatchPAT™ at baseline (5 nights) and measured for one night after both exercise and control conditions. Results: Results showed no effect of the exercise intervention on cognition immediately post-intervention, nor an effect of acute exercise on any sleep variable. There was no mediating effect of sleep on associations between exercise and cognition. However, a change from baseline to post-intervention in light sleep and deep sleep did predict change in episodic memory at the ~24 h post-intervention cognitive assessment, regardless of intervention condition. Discussion: There was no effect of acute high intensity exercise on sleep or cognition in the current study. However, results suggest that associations between sleep and cognition may exist independently of exercise in our sample. Further research is required, and such studies may aid in informing the most effective lifestyle interventions for cognitive health.

Call to action to properly utilize electron microscopy to measure organelles to monitor disease.

This review provides an overview of the current methods for quantifying mitochondrial ultrastructure, including cristae morphology, mitochondrial contact sites, and recycling machinery and a guide to utilizing electron microscopy to effectively measure these organelles. Quantitative analysis of mitochondrial ultrastructure is essential for understanding mitochondrial biology and developing therapeutic strategies for mitochondrial-related diseases. Techniques such as transmission electron microscopy (TEM) and serial block face-scanning electron microscopy, as well as how they can be combined with other techniques including confocal microscopy, super-resolution microscopy, and correlative light and electron microscopy are discussed. Beyond their limitations and challenges, we also offer specific magnifications that may be best suited for TEM analysis of mitochondrial, endoplasmic reticulum, and recycling machinery. Finally, perspectives on future quantification methods are offered.

Standardized Protocol for Chest Tube Management for Trauma Patients Significantly Decreases Complications.

Background: As health care shifts to a value-based model with a focus on patient outcomes per dollar spent, it is important to develop and evaluate standardized protocols that ultimately lead to improved patient outcomes and decreased hospital complications. Prior to our chest tube protocol, chest tube management at our Trauma Center was nonuniform and surgeon-specific. The aim of this study was to (1) develop an institutional standardized protocol for chest tube management at our Level II Trauma Center and (2) compare patient outcomes before and after the implementation of our protocol. Methods: An institutional, standardized protocol was initiated at our Level II-Certified Trauma Center teaching hospital in 2014. An IRB-approved, single-institution retrospective chart review was performed between January 2011 and May 2017, in order to capture the 3 years prior and 3 years after protocol implementation. All patients with a diagnosis of hemothorax or pneumothorax (H/PTX) from blunt or penetrating trauma that resulted in a >24 French chest tube placement were included in the study. Patients were excluded if interventional radiology (IR) placed the chest tube, the mechanism was nontraumatic, or the patient expired at index hospitalization. Univariate analyses were performed to evaluate significant differences in patient outcomes before and after the implementation of the protocol. Results: A total of 143 patients were analyzed for this study, with 43 preprotocol patients and 100 postprotocol patients. Hospital length of stay (LOS), persistent H/PTX, and the need for further surgical intervention all improved after the implementation of the standardized protocol (p < 0.04). Conclusions: Our standardized protocol for chest tube management at our Level II Trauma Center significantly improved patient outcomes and can serve as a model for similar institutions.

Profiles of resilient psychosocial function during three isolated ski expeditions in the High Arctic.

To successfully complete a Polar expedition individuals and teams must respond resiliently to the environmental, psychological, and social demands they face. In this study we examined profiles of resilient function in seven people from three expeditions in the High Arctic. Using a structured daily diary, participants reported on experiences of physical health (morning and evening), affect, team cohesion, performance, and potential explanatory factors including sleep, demand appraisals, events, and coping strategies. Notable intra- and inter-individual variability was observed in daily reports and all profiles could be interpreted as representing resilient function. A number of significant relationships were found between markers of resilient physical and psychosocial function and potential explanatory variables. For example, there was much more daily variability in an individual's reporting of positive affect than prior research might imply, and what prior research designs could capture. Further, while negative affect tended to remain low and stable, our findings reveal that even minor and infrequent increases in negative emotions were significantly associated with other variables in the network. Finally, across the expedition period individual coping resources consistently exceeded demands, suggesting that individuals viewed the expedition as a challenge and not a threat. More broadly, these findings inform efforts to monitor, and maintain resilience when operating in Polar and other extreme settings.

Changes in an Enzyme Ensemble During Catalysis Observed by High Resolution XFEL Crystallography.

Enzymes populate ensembles of structures with intrinsically different catalytic proficiencies that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL) to observe catalysis in a designed mutant (G150T) isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations and formation of the thioimidate catalytic intermediate selects for catalytically competent substates. A prior proposal for active site cysteine charge-coupled conformational changes in ICH is validated by determining structures of the enzyme over a range of pH values. A combination of large molecular dynamics simulations of the enzyme in crystallo and time-resolved electron density maps shows that ionization of the general acid Asp17 during catalysis causes additional conformational changes that propagate across the dimer interface, connecting the two active sites. These ionization-linked changes in the ICH conformational ensemble permit water to enter the active site in a location that is poised for intermediate hydrolysis. ICH exhibits a tight coupling between ionization of active site residues and catalysis-activated protein motions, exemplifying a mechanism of electrostatic control of enzyme dynamics.

Protein target highlights in CASP15: Analysis of models by structure providers.

We present an in-depth analysis of selected CASP15 targets, focusing on their biological and functional significance. The authors of the structures identify and discuss key protein features and evaluate how effectively these aspects were captured in the submitted predictions. While the overall ability to predict three-dimensional protein structures continues to impress, reproducing uncommon features not previously observed in experimental structures is still a challenge. Furthermore, instances with conformational flexibility and large multimeric complexes highlight the need for novel scoring strategies to better emphasize biologically relevant structural regions. Looking ahead, closer integration of computational and experimental techniques will play a key role in determining the next challenges to be unraveled in the field of structural molecular biology.