Discovery of phosphorylated lantibiotics with proimmune activity that regulate the oral microbiome.

Lantibiotics are ribosomally synthesized and posttranslationally modified peptides (RiPPs) that are produced by bacteria. Interest in this group of natural products is increasing rapidly as alternatives to conventional antibiotics. Some human microbiome-derived commensals produce lantibiotics to impair pathogens' colonization and promote healthy microbiomes. Streptococcus salivarius is one of the first commensal microbes to colonize the human oral cavity and gastrointestinal tract, and its biosynthesis of RiPPs, called salivaricins, has been shown to inhibit the growth of oral pathogens. Herein, we report on a phosphorylated class of three related RiPPs, collectively referred to as salivaricin 10, that exhibit proimmune activity and targeted antimicrobial properties against known oral pathogens and multispecies biofilms. Strikingly, the immunomodulatory activities observed include upregulation of neutrophil-mediated phagocytosis, promotion of antiinflammatory M2 macrophage polarization, and stimulation of neutrophil chemotaxis-these activities have been attributed to the phosphorylation site identified on the N-terminal region of the peptides. Salivaricin 10 peptides were determined to be produced by S. salivarius strains found in healthy human subjects, and their dual bactericidal/antibiofilm and immunoregulatory activity may provide new means to effectively target infectious pathogens while maintaining important oral microbiota.

Early Versus Late Initiation of Direct Oral Anticoagulants After Ischemic Stroke in People With Atrial Fibrillation and Hemorrhagic Transformation: Prespecified Subanalysis of the Randomized Controlled ELAN Trial.

BACKGROUND: Whether hemorrhagic transformation (HT) modifies the treatment effect of early compared with late initiation of direct oral anticoagulation in people with ischemic stroke and atrial fibrillation is unknown. METHODS: This is a post hoc analysis of the ELAN trial (Early Versus Late Initiation of Direct Oral Anticoagulants in Post-Ischaemic Stroke Patients With Atrial Fibrillation). The primary outcome was a composite of recurrent ischemic stroke, symptomatic intracranial hemorrhage, major extracranial bleeding, systemic embolism, or vascular death within 30 days. Secondary outcomes were the individual components, 30- and 90-day functional outcome. We estimated outcomes based on HT, subclassified as hemorrhagic infarction (HI) or parenchymal hemorrhage (PH) on prerandomization imaging (core laboratory rating) using adjusted risk differences between treatment arms. RESULTS: Overall, 247 of 1970 participants (12.5%) had HT (114 HI 1, 77 HI 2, 34 PH 1, 22 PH 2). For the primary outcome, the estimated adjusted risk difference (early versus late) was -2.2% (95% CI, -7.8% to 3.5%) in people with HT (HI: -4.7% [95% CI, -10.8% to 1.4%]; PH: 6.1% [95% CI, -8.5% to 20.6%]) and -0.9% (95% CI, -2.6% to 0.8%) in people without HT. Numbers of symptomatic intracranial hemorrhage were identical in people with and without HT. With early treatment, the estimated adjusted risk difference for poor 90-day functional outcome (modified Rankin Scale score, 3-6) was 11.5% (95% CI, -0.8% to 23.8%) in participants with HT (HI: 7.4% [95% CI, -6.4% to 21.2%]; PH: 25.1% [95% CI, 0.2% to 50.0%]) and -2.6% (95% CI, -7.1% to 1.8%) in people without HT. CONCLUSIONS: We found no evidence of major treatment effect heterogeneity or safety concerns with early compared with late direct oral anticoagulation initiation in people with and without HT. However, early direct oral anticoagulation initiation may worsen functional outcomes in people with PH. REGISTRATION: URL: http://www.clinicaltrials.gov; Unique identifier: NCT03148457.

Identifying a therapeutic window of opportunity for people living with primary sclerosing cholangitis: Embryology and the overlap of inflammatory bowel disease with immune-mediated liver injury.

Primary sclerosing cholangitis (PSC) is a variably progressive, fibrosis-causing autoimmune disorder of the intrahepatic and extrahepatic bile ducts of unclear etiology. PSC is commonly (in 60%-90% of cases) associated with an inflammatory bowel disease (IBD) like PSC-IBD and less commonly with an autoimmune hepatitis (AIH) like PSC-AIH or AIH-overlap disorder. Hepatologists and Gastroenterologists often consider these combined conditions as distinctly different from the classical forms in isolation. Here, we review recent epidemiologic observations and highlight that PSC-IBD and PSC-AIH overlap appear to represent aspects of a common PSC clinico-pathological pathway and manifest in an age-of-presentation-dependent manner. Particularly from the pediatric experience, we hypothesize that all cases of PSC likely originate from a complex "Early PSC"-"IBD"-"AIH" overlap in which PSC defines the uniquely and variably associated "AIH" and "IBD" components along an individualized lifetime continuum. We speculate that a distinctly unique, "diverticular autoimmunity" against the embryonic cecal- and hepatic diverticulum-derived tissues may be the origin of this combined syndrome, where "AIH" and "IBD" variably commence then variably fade while PSC progresses with age. Our hypothesis provides an explanation for the age-dependent variation in the presentation and progression of PSC. This is critical for the optimal targeting of studies into PSC etiopathogenesis and emphasizes the concept of a "developmental window of opportunity for therapeutic mitigation" in what is currently recognized as an irreversible disease process. The discovery of such a window would be critically important for the targeting of interventions, both the administration of current therapies and therapeutic trial planning.

Repurposing dried blood spot device technology to examine bile acid profiles in human dried fecal spot samples.

Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: 1) healthy individuals, 2) individuals with diarrhea, and 3) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After 4 mo, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrates that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.NEW & NOTEWORTHY Stool analysis in remote settings can be challenging, as the samples must be stored at -80°C and transported on dry ice for downstream processing. Our work indicates that dried fecal spots (DFS) on Capitainer quantitative DBS (qDBS) devices can be stored and shipped at ambient temperature and yields the same bile acid profiles as traditional samples. This approach has broad applications for patient home testing and sample collection in rural communities or resource-limited countries.

Early Versus Late Initiation of Endovascular Therapy in Patients with Severe Cerebral Venous Sinus Thrombosis.

BACKGROUND: Endovascular therapy (EVT) for severe cerebral venous sinus thrombosis (CVST) is controversial in terms of indication and clinical benefit. The impact of delay of EVT on functional recovery is unclear. This study aimed to investigate the effect of early versus late initiation of EVT in severe CVST. METHODS: From prospective EVT and CVST registries, patients with CVST diagnosed between January 2010 and December 2022 were retrospectively identified for this multicenter collaboration. EVT was considered in severe CVST with features prone to a poor prognosis. We compared early (< 24 h) with late (> 24 h) initiation of EVT after the presentation in the emergency department and subsequent CVST diagnosis. Outcome parameters included functional independence (modified Rankin Scale [mRS] score 0-2) at 90 days, mRS score at discharge, in-hospital mortality, and mortality at 3 months. RESULTS: Of 363 patients with CVST, 45 (12.4%; 31 [early EVT] vs. 14 [late EVT]) were included in this study. We found a higher proportion of patients with functional independence at 3 months among early versus late EVT (66.7% vs. 27.3%; odds ratio [OR] 5.3; 95% confidence interval 1.02-25; p = 0.036). In multivariate logistic regression, late EVT was inversely correlated with functional independence (OR 0.17 [0.04-0.83]; p = 0.011). The mortality rate was 16.7% versus 36.4% (mRS 6 at 3 months, OR 0.34, 95% confidence interval 0.07-1.75; p = 0.217) at 90 days for early versus late EVT. CONCLUSIONS: We observed a higher rate of functional independence in patients with early EVT. These preliminary findings must be confirmed in subsequent randomized controlled trials evaluating a "time-is-brain" paradigm for EVT in CVST.

Symptomatic visual snow in acute ischemic stroke: A case series.

Visual snow is the main symptom of visual snow syndrome, a disorder of predominantly visual disturbances initially described in patients without abnormalities on ancillary investigations. We present a case series of patients with visual snow in the setting of acute ischemic stroke. The first and second patient reported previous episodic visual snow with migraine attacks. The third patient experienced visual snow for the first time during the ischemic stroke. In the first patient, the ischemic stroke affected the right and left precuneus and the right lingual gyrus. In the second patient, the ischemic stroke was located in the left lingual gyrus, parts of the left fusiform and parahippocampal gyrus, left dorso-lateral thalamus, and left cerebellar hemisphere. In the third patient, occipital pole, trunk of the corpus callosum on the right, right paramedian pons, right cerebellar hemisphere, and vermis were affected. Our case series indicates that the symptom visual snow can be caused by vascular lesions in areas of visual processing. Because patients did not meet criteria for visual snow syndrome, dysfunction in the affected areas might only explain part of the complex pathophysiology of visual snow syndrome.

Bacteroides ovatus Promotes IL-22 Production and Reduces Trinitrobenzene Sulfonic Acid-Driven Colonic Inflammation.

The intestinal microbiota influences the development and function of the mucosal immune system. However, the exact mechanisms by which commensal microbes modulate immunity is not clear. We previously demonstrated that commensal Bacteroides ovatus ATCC 8384 reduces mucosal inflammation. Herein, we aimed to identify immunomodulatory pathways employed by B. ovatus. In germ-free mice, mono-association with B. ovatus shifted the CD11b+/CD11c+ and CD103+/CD11c+ dendritic cell populations. Because indole compounds are known to modulate dendritic cells, B. ovatus cell-free supernatant was screened for tryptophan metabolites by liquid chromatography-tandem mass spectrometry and larger quantities of indole-3-acetic acid were detected. Analysis of cecal and fecal samples from germ-free and B. ovatus mono-associated mice confirmed that B. ovatus could elevate indole-3-acetic acid concentrations in vivo. Indole metabolites have previously been shown to stimulate immune cells to secrete the reparative cytokine IL-22. Addition of B. ovatus cell-free supernatant to immature bone marrow-derived dendritic cells stimulated IL-22 secretion. The ability of IL-22 to drive repair in the intestinal epithelium was confirmed using a physiologically relevant human intestinal enteroid model. Finally, B. ovatus shifted the immune cell populations in trinitrobenzene sulfonic acid-treated mice and up-regulated colonic IL-22 expression, effects that correlated with decreased inflammation. Our data suggest that B. ovatus-produced indole-3-acetic acid promotes IL-22 production by immune cells, yielding beneficial effects on colitis.

The metabolic profile of Bifidobacterium dentium reflects its status as a human gut commensal.

BACKGROUND: Bifidobacteria are commensal microbes of the mammalian gastrointestinal tract. In this study, we aimed to identify the intestinal colonization mechanisms and key metabolic pathways implemented by Bifidobacterium dentium. RESULTS: B. dentium displayed acid resistance, with high viability over a pH range from 4 to 7; findings that correlated to the expression of Na+/H+ antiporters within the B. dentium genome. B. dentium was found to adhere to human MUC2+ mucus and harbor mucin-binding proteins. Using microbial phenotyping microarrays and fully-defined media, we demonstrated that in the absence of glucose, B. dentium could metabolize a variety of nutrient sources. Many of these nutrient sources were plant-based, suggesting that B. dentium can consume dietary substances. In contrast to other bifidobacteria, B. dentium was largely unable to grow on compounds found in human mucus; a finding that was supported by its glycosyl hydrolase (GH) profile. Of the proteins identified in B. dentium by proteomic analysis, a large cohort of proteins were associated with diverse metabolic pathways, indicating metabolic plasticity which supports colonization of the dynamic gastrointestinal environment. CONCLUSIONS: Taken together, we conclude that B. dentium is well adapted for commensalism in the gastrointestinal tract.

Seasonal patterns and associations in the incidence of acute ischemic stroke requiring mechanical thrombectomy.

BACKGROUND: In order to identify risk periods with an increased demand in technical and human resources, we tried to determine patterns and associations in the incidence of acute ischemic stroke due to embolic large vessel occlusions (eLVO) requiring mechanical thrombectomy (MT). METHODS: We conducted a time series analysis over a 9-year period (2010-2018) based on observational data in order to detect seasonal patterns in the incidence of MT due to eLVO (n = 2628 patients). In a series of sequential negative binominal regression models, we aimed to detect further associations (e.g., temperature, atmospheric pressure, air pollution). RESULTS: There was a 6-month seasonal pattern in the incidence of MT due to eLVO (p = 0.024) peaking in March and September. Colder overall temperature was associated with an increase in MT due to eLVO (average marginal effect [AME], [95% CI]: -0.15 [-0.30-0.0001]; p = 0.05; per °C). A current increase in the average monthly temperature was associated with a higher incidence of MT due to eLVO (0.34 [0.11-0.56]; p = 0.003). Atmospheric pressure was positively correlated with MT due to eLVO (0.38 [0.13-0.64]; p = 0.003; per hectopascal [hPa]). We could detect no causal correlation between air pollutants and MT due to eLVO. CONCLUSIONS: Our data suggest a 6-month seasonal pattern in the incidence of MT due to eLVO peaking in spring and early autumn. This might be attributed to two different factors: (1) a current temperature rise (comparing the average monthly temperature in consecutive months) and (2) colder overall temperature. These results could help to identify risk periods requiring an adaptation in local infrastructure.

Cardiac autonomic dynamics during sleep are lost in patients with TIA and stroke.

Ischaemic stroke is accompanied by important alterations of cardiac autonomic control, which have an impact on stroke outcome. In sleep, cardiac autonomic control oscillates with a predominant sympathetic modulation during REM sleep. We aimed to assess cardiac autonomic control in different sleep stages in patients with ischaemic stroke. Forty-five patients enrolled in the prospective, multicentre SAS-CARE study but without significant sleep-disordered breathing (apnea-hypopnea index < 15/hr) and without atrial fibrillation were included in this analysis. The mean age was 56 years, 68% were male, 76% had a stroke (n = 34, mean National Institutes of Health Stroke Scale [NIHSS] score of 5, 11 involving the insula) and 24% (n = 11) had a transitory ischaemic attack. Cardiac autonomic control was evaluated using three different tools (spectral, symbolic and entropy analysis) according to sleep stages on short segments of 250 beats in all patients. Polysomnographic studies were performed within 7 days and 3 months after the ischaemic event. No significant differences in cardiac autonomic control between sleep stages were observed in the acute phase and after 3 months. Predominant vagal modulation and decreased sympathetic modulation were observed across all sleep stages in ischaemic stroke involving the insula. Patients with ischaemic stroke and transitory ischaemic attack present a loss of cardiac autonomic dynamics during sleep in the first 3 months after the ischaemic event. This change could represent an adaptive phenomenon, protecting the cardiovascular system from the instabilities of autonomic control, or a risk factor for stroke, which precedes the ischaemic event.

Peptide Vaccine Formulation Controls the Duration of Antigen Presentation and Magnitude of Tumor-Specific CD8+ T Cell Response.

Despite remarkable progresses in vaccinology, therapeutic cancer vaccines have not achieved their full potential. We previously showed that an excessively long duration of Ag presentation critically reduced the quantity and quality of vaccination-induced T cell responses and subsequent antitumor efficacy. In this study, using a murine model and tumor cell lines, we studied l-tyrosine amino acid-based microparticles as a peptide vaccine adjuvant with a short-term Ag depot function for the induction of tumor-specific T cells. l-Tyrosine microparticles did not induce dendritic cell maturation, and their adjuvant activity was not mediated by inflammasome activation. Instead, prolonged Ag presentation in vivo translated into increased numbers and antitumor activity of vaccination-induced CD8+ T cells. Indeed, prolonging Ag presentation by repeated injection of peptide in saline resulted in an increase in T cell numbers similar to that observed after vaccination with peptide/l-tyrosine microparticles. Our results show that the duration of Ag presentation is critical for optimal induction of antitumor T cells, and can be manipulated through vaccine formulation.

Positional stable isotope tracer analysis reveals carbon routes during ammonia metabolism of Aedes aegypti mosquitoes.

In Aedes aegypti females, the ammonia released during blood meal digestion is partially metabolized to facilitate the disposal of excess nitrogen. In this study, we used low- and high-resolution liquid chromatography-mass spectrometry (LC/MS) techniques to investigate the role of glucose during ammonia detoxification. Mosquitoes were fed a blood meal supplemented with [1,2-13C2]glucose, and downstream metabolites were measured for 24 h. Quantification of [13C] amino acids in the entire mosquito body was conducted without sample derivatization using selected reaction monitoring of mass transitions that are indicative of the structural position of [13C] atom incorporation. Identification of unlabeled and [13C] isotopologs of 43 compounds, including amino acids, amino acid derivatives, and organic acids, was performed by high-resolution LC/MS techniques. Blood-fed mosquitoes synthesized [13C] metabolites in mainly 2 carbon positions from [1,2-13C2]glucose. [13C2]Ala and [13C2]Pro were the most abundant and rapidly labeled amino acids synthesized. Additional [13C] amino acids, [13C] amino acid derivatives, and [13C] organic acids in 1 or 2 carbon positions were also identified. Two kinetic routes were proposed based on the incorporation of a [13C] atom at position 1 in specific amino acids. Our findings provide evidence that glucose is used for ammonia detoxification and [13C] uric acid synthesis through multiple metabolic pathways, uncovering a metabolic link at the carbon atomic level in ammonia metabolism of A. aegypti-Horvath, T. D., Dagan, S., Lorenzi, P. L., Hawke, D. H., Scaraffia, P. Y. Positional stable isotope tracer analysis reveals carbon routes during ammonia metabolism of Aedes aegypti mosquitoes.

Impact of Smoking on Clinical Outcome and Recanalization After Intravenous Thrombolysis for Stroke: Multicenter Cohort Study.

BACKGROUND AND PURPOSE: The impact of smoking on prognosis after stroke is controversial. We aimed to assess the relationship between smoking status and stroke outcome after intravenous thrombolysis in a large cohort study by adjusting for potential confounders and incorporating recanalization rates. METHODS: In a prospective observational multicenter study, we analyzed baseline and outcome data of consecutive patients with acute ischemic stroke treated with intravenous thrombolysis. Using uni- and multivariable modeling, we assessed whether smoking was associated with favorable outcome (modified Rankin Scale score of 0-1) and mortality. In addition, we also measured the occurrence of symptomatic intracranial hemorrhage and recanalization of middle cerebral artery. Patients reporting active cigarette use were classified as smokers. RESULTS: Of 1865 patients, 19.8% were smokers (n=369). They were younger (mean 63.5 versus 71.3 years), less often women (56% versus 72.1%), and suffered less often from hypertension (61.3% versus 70.1%) and atrial fibrillation (22.7% versus 35.6%) when compared with nonsmokers. Favorable outcome and 3-month mortality were in favor of smokers in unadjusted analyses (45.8% versus 39.5% and 9.3% versus 15.8%, respectively), whereas symptomatic intracranial hemorrhage was comparable in both cohorts. Smoking was not associated with clinical outcome and mortality after adjusting for confounders (odds ratio, 1.20; 95% confidence interval, 0.91-1.61; P=0.197 and odds ratio, 1.08; 95% confidence interval, 0.68-1.71; P=0.755, respectively). However, smoking still independently predicted recanalization of middle cerebral artery in multivariable analyses (odds ratio, 2.68; 95% confidence interval, 1.11-6.43; P=0.028). CONCLUSIONS: Our study suggests that good outcome in smokers is mainly related to differences in baseline characteristics and not to biological effects of smoking. The higher recanalization rates in smokers, however, call for further studies.

Characterizing arginine, ornithine, and putrescine pathways in enteric pathobionts.

Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream products of its metabolism remain undefined in various gut bacteria. To bridge this knowledge gap, we employed genomic screening to pinpoint relevant metabolic targets. We also devised a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method to measure the levels of arginine, its upstream precursors, and downstream products in cell-free conditioned media from enteric pathobionts, including Escherichia coli, Klebsiella aerogenes, K. pneumoniae, Pseudomonas fluorescens, Acinetobacter baumannii, Streptococcus agalactiae, Staphylococcus epidermidis, S. aureus, and Enterococcus faecalis. Our findings revealed that all selected bacterial strains consumed glutamine, glutamate, and arginine, and produced citrulline, ornithine, and GABA in our chemically defined medium. Additionally, E. coli, K. pneumoniae, K. aerogenes, and P. fluorescens were found to convert arginine to agmatine and produce putrescine. Interestingly, arginine supplementation promoted biofilm formation in K. pneumoniae, while ornithine supplementation enhanced biofilm formation in S. epidermidis. These findings offer a comprehensive insight into arginine-ornithine metabolism in enteric pathobionts.

Intravenous thrombolysis in patients with recent intake of direct oral anticoagulants: A target trial analysis after the liberalization of institutional guidelines.

INTRODUCTION: This study aimed to report the safety and efficacy of off-label intravenous thrombolysis (IVT) with alteplase after sequentially liberalizing our institutional guidelines allowing IVT for patients under direct oral anticoagulants (DOACs) regardless of plasma levels, time of last intake, and without prior anticoagulation reversal therapy. PATIENTS AND METHODS: We utilized the target-trial methodology to emulate hypothetical criteria of a randomized controlled trial in our prospective stroke registry. Consecutive DOAC patients (06/2021-11/2023) otherwise qualifying for IVT were included. Safety and efficacy outcomes (symptomatic intracranial hemorrhage [ICH], any radiological ICH, major bleeding, 90-day mortality, 90-day good functional outcome [mRS 0-2 or return to baseline]) were assessed using inverse-probability-weighted regression-adjustment comparing patients with versus without IVT. RESULTS: Ninety eight patients fulfilled the target-trial criteria. IVT was given in 49/98 (50%) patients at a median of 178 (interquartile range 134-285) min after symptom onset with median DOAC plasma level of 77 ng/ml (15 patients had plasma levels > 100 ng/ml; 25/49 [51%] were treated within 12 h after last DOAC ingestion). Endovascular therapy was more frequent in patients without IVT (73% vs 33%). Symptomatic ICH occurred in 0/49 patients receiving IVT and 2/49 patients without IVT (adjusted difference -2.5%; 95% CI -5.9 to 0.8). The rates of any radiological ICH were comparable. Patients receiving IVT were more likely to have good functional outcomes. DISCUSSION AND CONCLUSION: After liberalizing our approach for IVT regardless of recent DOAC intake, we did not experience any safety concerns. The association of IVT with better functional outcomes warrants prospective randomized controlled trials.

Clostridioides difficile colonization is not mediated by bile salts and requires Stickland fermentation of proline in an in vitro model of infection.

Treatment with antibiotics is a major risk factor for Clostridioides difficile infection, likely due to depletion of the gastrointestinal microbiota. Two microbiota-mediated mechanisms thought to limit C. difficile colonization include conversion of conjugated primary bile salts into secondary bile salts toxic to C. difficile growth, and competition between the microbiota and C. difficile for limiting nutrients. Using a continuous flow model of the distal colon, we investigated how treatment with six clinically-used antibiotics influenced susceptibility to C. difficile infection in 12 different microbial communities cultivated from healthy individuals. Antibiotic treatment reduced microbial richness; disruption varied by antibiotic class and microbiota composition, but did not correlate with C. difficile susceptibility. Antibiotic treatment also disrupted microbial bile salt metabolism, increasing levels of the primary bile salt, cholate, and decreasing levels of the secondary bile salt, deoxycholate. However, decreased levels of deoxycholate did not correlate with increased C. difficile susceptibility. Further, bile salts were not required to inhibit C. difficile colonization. We tested whether amino acid fermentation contributed to persistence of C. difficile in antibiotic-treated communities. C. difficile mutants unable to use proline as an electron acceptor in Stickland fermentation due to disruption of proline reductase (Δ prdB ) had significantly lower levels of colonization than wild-type strains in four of six antibiotic-treated communities tested. This data provides further support for the importance of bile salt-independent mechanisms in regulating colonization of C. difficile . IMPORTANCE: C. difficile is one of the leading causes of hospital-acquired infections and antibiotic-associated diarrhea. Several potential mechanisms through which the microbiota can limit C. difficile infection have been identified and are potential targets for new therapeutics. However, it is unclear which mechanisms of C. difficile inhibition represent the best targets for development of new therapeutics. These studies demonstrate that in a complex in vitro model of C. difficile infection, colonization resistance is independent of microbial bile salt metabolism. Instead, the ability of C. difficile to colonize is dependent upon its ability to metabolize proline, although proline-dependent colonization is context-dependent and is not observed in all disrupted communities. Altogether, these studies support the need for further work to understand how bile-independent mechanisms regulate C. difficile colonization.

Phylogenetically diverse bacterial species produce histamine.

Histamine is an important biogenic amine known to impact a variety of patho-physiological processes ranging from allergic reactions, gut-mediated anti-inflammatory responses, and neurotransmitter activity. Histamine is found both endogenously within specialized host cells and exogenously in microbes. Exogenous histamine is produced through the decarboxylation of the amino acid L-histidine by bacterial-derived histidine decarboxylase enzymes. To investigate how widespread histamine production is across bacterial species, we examined 102,018 annotated genomes in the Integrated Microbial Genomes Database and identified 3,679 bacterial genomes (3.6 %) which possess the enzymatic machinery to generate histamine. These bacteria belonged to 10 phyla: Bacillota, Bacteroidota, Actinomycetota, Pseudomonadota, Lentisphaerota, Fusobacteriota, Armatimonadota, Cyanobacteriota, Thermodesulfobacteriota, and Verrucomicrobiota. The majority of the identified bacteria were terrestrial or aquatic in origin, although several bacteria originated in the human gut microbiota. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics to confirm our genome discoveries correlated with L-histidine-to-histamine conversion in a chemically defined bacterial growth medium by a cohort of select environmental and human gut bacteria. We found that environmental microbes Vibrio harveyi, Pseudomonas fluorescens and Streptomyces griseus generated considerable levels of histamine (788 - 8,730 ng/mL). Interestingly, we found higher concentrations of histamine produced by gut-associated Fusobacterium varium, Clostridium perfringens, Limosilactobacillus reuteri and Morganella morganii (8,510--82,400 ng/mL). This work expands our knowledge of histamine production by diverse microbes.

Early vs Late Anticoagulation in Minor, Moderate, and Major Ischemic Stroke With Atrial Fibrillation: Post Hoc Analysis of the ELAN Randomized Clinical Trial.

Importance: Whether infarct size modifies the treatment effect of early vs late direct oral anticoagulant (DOAC) initiation in people with ischemic stroke and atrial fibrillation is unknown. Objective: To assess whether infarct size modifies the safety and efficacy of early vs late DOAC initiation. Design, Setting, and Participants: Post hoc analysis of participants from the multinational (>100 sites in 15 countries) randomized clinical Early Versus Later Anticoagulation for Stroke With Atrial Fibrillation (ELAN) trial who had (1) acute ischemic stroke, (2) atrial fibrillation, and (3) brain imaging available before randomization. The ELAN trial was conducted between October 2017 and December 2022. Data were analyzed from October to December 2023 for this post hoc analysis. Intervention: Early vs late DOAC initiation after ischemic stroke. Early DOAC initiation was within 48 hours for minor or moderate stroke or on days 6 to 7 for major stroke; late DOAC initiation was on days 3 to 4 for minor stroke, days 6 to 7 for moderate stroke, and days 12 to 14 for major stroke. Main Outcomes and Measures: The primary outcome was a composite of recurrent ischemic stroke, symptomatic intracranial hemorrhage, extracranial bleeding, systemic embolism, or vascular death within 30 days. The outcome was assessed according to infarct size (minor, moderate, or major) using odds ratios and risk differences between treatment arms. Interrater reliability for infarct size between the core laboratory and local raters was assessed, and whether this modified the estimated treatment effects was also examined. Results: A total of 1962 of the original 2013 participants (909 [46.3%] female; median [IQR] age, 77 [70-84] years) were included. The primary outcome occurred in 10 of 371 participants (2.7%) with early DOAC initiation vs 11 of 364 (3.0%) with late DOAC initiation among those with minor stroke (odds ratio [OR], 0.89; 95% CI, 0.38-2.10); in 11 of 388 (2.8%) with early DOAC initiation vs 14 of 392 (3.6%) with late DOAC initiation among those with moderate stroke (OR, 0.80; 95% CI, 0.35-1.74); and in 8 of 219 (3.7%) with early DOAC initiation vs 16 of 228 (7.0%) with late DOAC initiation among those with major stroke (OR, 0.52; 95% CI, 0.21-1.18). The 95% CI for the estimated risk difference of the primary outcome in early anticoagulation was -2.78% to 2.12% for minor stroke, -3.23% to 1.76% for moderate stroke, and -7.49% to 0.81% for major stroke. There was no significant treatment interaction for the primary outcome. For infarct size, interrater reliability was moderate (κ = 0.675; 95% CI, 0.647-0.702) for local vs core laboratory raters and strong (κ = 0.875; 95% CI, 0.855-0.894) between core laboratory raters. Conclusions and Relevance: The treatment effect of early DOAC initiation did not differ in people with minor, moderate, or major stroke assessed by brain imaging. Early treatment was not associated with a higher rate of adverse events, especially symptomatic intracranial hemorrhage, for any infarct size, including major stroke. Trial Registration: ClinicalTrials.gov Identifier: NCT03148457.

The Impact of Health and Education on Labor Force Participation in Aging Societies: Projections for the United States and Germany from Dynamic Microsimulations.

We project the labor force in the United States to 2060 and contrast the outcomes with comparative projections for Germany. In both countries, the population will age, but the demographic dynamics are fundamentally different. According to our dynamic microsimulations, the labor force in the U.S. will increase by 17 percent between 2020 and 2060 (about 29 million workers) despite population aging. In contrast, the labor force in Germany will decline by 11 percent (about 4.5 million workers). Our baseline projections indicate that an expansion of education will increase the labor force by about 3 million persons in the United States and about half a million persons in Germany by 2060. In several what-if scenarios, we examine the effects of further expanding education and of removing health barriers on labor force participation. Higher educational attainment among those with currently low education has the largest impact on labor force participation, relative to the additional years of schooling. However, health improvements and the labor market integration of people with health limitations suggest a larger increase in labor force participation rates. Using Sweden as a benchmark, we show that reducing the health participation gap would increase the U.S. labor force by as much as 13 million people in 2060 (+6.8 percent compared to our baseline).

A high-throughput protocol for measuring solution pH of bacterial cultures using UV-Vis absorption spectrophotometry.

We present a protocol for measuring the pH of cell-free bacterial-conditioned media based on changes in the ultraviolet-visible (UV-Vis) absorbance spectrum using the pH indicator dye litmus. This protocol includes detailed procedures for performing bacterial culturing, examining bacterial growth, collecting cell-free supernatant, litmus dye addition, and pH-based calibration curve preparations. This assay has been designed for flexible formatting that can accommodate both high-volume and low-volume sample sets.