Embolic Stroke of Undetermined Source: New Data and New Controversies on Cardiac Monitoring and Anticoagulation.

Embolic strokes of undetermined source (ESUS) represent 9%-25% of all ischemic strokes. Based on the suspicion that a large proportion of cardioembolic sources remain undetected among embolic stroke of undetermined source patients, it has been hypothesized that a universal approach of anticoagulation would be better than aspirin for preventing recurrent strokes. However, 4 randomized controlled trials (RCTs), with different degrees of patient selection, failed to confirm this hypothesis. In parallel, several RCTs consistently demonstrated that prolonged cardiac monitoring increased atrial fibrillation detection and anticoagulation initiation compared with usual care in patients with ESUS, and later in individuals with ischemic stroke of known cause (e.g., large or small vessel disease). However, none of these trials or subsequent meta-analyses of all available RCTs have shown a reduction in stroke recurrence associated with the use of prolonged cardiac monitoring. In this article, we review the clinical and research implications of recent RCTs of antithrombotic therapy in patients with ESUS and in high-risk populations with and without stroke, with device-detected asymptomatic atrial fibrillation.

Cardiolipin clustering promotes mitochondrial membrane dynamics.

Cardiolipin (CL) is a mitochondria-specific phospholipid that forms heterotypic interactions with membrane-shaping proteins and regulates the dynamic remodeling and function of mitochondria. However, the precise mechanisms through which CL influences mitochondrial morphology are not well understood. In this study, employing molecular dynamics (MD) simulations, we observed CL localize near the membrane-binding sites of the mitochondrial fusion protein Optic Atrophy 1 (OPA1). To validate these findings experimentally, we developed a bromine-labeled CL probe to enhance cryoEM contrast and characterize the structure of OPA1 assemblies bound to the CL-brominated lipid bilayers. Our images provide direct evidence of interactions between CL and two conserved motifs within the paddle domain (PD) of OPA1, which control membrane-shaping mechanisms. We further observed a decrease in membrane remodeling activity for OPA1 in lipid compositions with increasing concentrations of monolyso-cardiolipin (MLCL). Suggesting that the partial replacement of CL by MLCL accumulation, as observed in Barth syndrome-associated mutations of the tafazzin phospholipid transacylase, compromises the stability of protein-membrane interactions. Our analyses provide insights into how biological membranes regulate the mechanisms governing mitochondrial homeostasis.

Extracellular volume measured by whole body CT scans predicts chronic cardiotoxicity in breast cancer patients treated with neoadjuvant therapies based on anthracyclines: A retrospective study.

INTRODUCTION: Neoadjuvant chemotherapies for breast cancer (BC) are effective but potentially cardiotoxic, and expose long survivors at risk of chemotherapy-related cardiac dysfunction (CTRCD). Unfortunately, early screening for CTRCD has actual diagnostic limits. Myocardial extracellular volume (mECV) is a radiological marker used in cardiac CT scans and cardiac magnetic resonance for diagnosis and follow-up of CTRCD. It can be measured in whole-body CT (WB-CT) scan, routinely performed in patients at high risk of relapse, to evaluate CTRCD occurrence during oncological follow-up. METHODS: 82 WB-CT scans were examined at baseline (T0) and during oncological follow-up at first year (T1) and fifth year (T5) after the end of neoadjuvant treatment. mECV was measured at 1 min (PP) and 5 min (DP) after contrast injection. 31 echocardiograms were retrieved in T1 to perform a linear correlation between mECV and left ventricular ejection fraction (LVEF). RESULTS: mECV values in T0 were similar between the two groups both in PP and in DP. Significant results were found for PP values in T1 (37.0 % vs 32 %, p = 0.0005) and in T5 (27.2 % vs 31.2 %, p = 0.025). A cut-off value of 35 % in PP proved significant in T1 (OR = 12.4, p = 0.004), while mECV was inversely correlated with LVEF both in PP (adj-S = -3.54, adj-p = 0.002) and in DP (adj-S = -2.51, adj-p = 0.0002), suggesting a synergistic action with the age at diagnosis (p < 0.0001, respectively). CONCLUSIONS: WB-CT scans performed during oncological reassessment in patients at high-risk of recurrence could be used for CTRCD screening in cardiovascular low-risk patients, especially in aging patients with mECV values above 35 %.

Sodium-glucose cotransporter 2 inhibitor dapagliflozin prevents ejection fraction reduction, reduces myocardial and renal NF-κB expression and systemic pro-inflammatory biomarkers in models of short-term doxorubicin cardiotoxicity.

Background: Anthracycline-mediated adverse cardiovascular events are among the leading causes of morbidity and mortality in patients with cancer. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) exert multiple cardiometabolic benefits in patients with/without type 2 diabetes, chronic kidney disease, and heart failure with reduced and preserved ejection fraction. We hypothesized that the SGLT2i dapagliflozin administered before and during doxorubicin (DOXO) therapy could prevent cardiac dysfunction and reduce pro-inflammatory pathways in preclinical models. Methods: Cardiomyocytes were exposed to DOXO alone or combined with dapagliflozin (DAPA) at 10 and 100 nM for 24 h; cell viability, iATP, and Ca++ were quantified; lipid peroxidation products (malondialdehyde and 4-hydroxy 2-hexenal), NLRP3, MyD88, and cytokines were also analyzed through selective colorimetric and enzyme-linked immunosorbent assay (ELISA) methods. Female C57Bl/6 mice were treated for 10 days with a saline solution or DOXO (2.17 mg/kg), DAPA (10 mg/kg), or DOXO combined with DAPA. Systemic levels of ferroptosis-related biomarkers, galectin-3, high-sensitivity C-reactive protein (hs-CRP), and pro-inflammatory chemokines (IL-1α, IL-1ß, IL-2, IL-4, IL-6, IL-10, IL-12, IL17-α, IL-18, IFN-γ, TNF-α, G-CSF, and GM-CSF) were quantified. After treatments, immunohistochemical staining of myocardial and renal p65/NF-kB was performed. Results: DAPA exerts cytoprotective, antioxidant, and anti-inflammatory properties in human cardiomyocytes exposed to DOXO by reducing iATP and iCa++ levels, lipid peroxidation, NLRP-3, and MyD88 expression. Pro-inflammatory intracellular cytokines were also reduced. In preclinical models, DAPA prevented the reduction of radial and longitudinal strain and ejection fraction after 10 days of treatment with DOXO. A reduced myocardial expression of NLRP-3 and MyD-88 was seen in the DOXO-DAPA group compared to DOXO mice. Systemic levels of IL-1ß, IL-6, TNF-α, G-CSF, and GM-CSF were significantly reduced after treatment with DAPA. Serum levels of galectine-3 and hs-CRP were strongly enhanced in the DOXO group; on the other hand, their expression was reduced in the DAPA-DOXO group. Troponin-T, B-type natriuretic peptide (BNP), and N-Terminal Pro-BNP (NT-pro-BNP) were strongly reduced in the DOXO-DAPA group, revealing cardioprotective properties of SGLT2i. Mice treated with DOXO and DAPA exhibited reduced myocardial and renal NF-kB expression. Conclusion: The overall picture of the study encourages the use of DAPA in the primary prevention of cardiomyopathies induced by anthracyclines in patients with cancer.

Differential Effects of Post-translational Modifications on the Membrane Interaction of Huntingtin Protein.

Huntington's disease is a neurodegenerative disorder caused by an expanded polyglutamine stretch near the N-terminus of the huntingtin (HTT) protein, rendering the protein more prone to aggregate. The first 17 residues in HTT (Nt17) interact with lipid membranes and harbor multiple post-translational modifications (PTMs) that can modulate HTT conformation and aggregation. In this study, we used a combination of biophysical studies and molecular simulations to investigate the effect of PTMs on the helicity of Nt17 in the presence of various lipid membranes. We demonstrate that anionic lipids such as PI4P, PI(4,5)P2, and GM1 significantly enhance the helical structure of unmodified Nt17. This effect is attenuated by single acetylation events at K6, K9, or K15, whereas tri-acetylation at these sites abolishes Nt17-membrane interaction. Similarly, single phosphorylation at S13 and S16 decreased but did not abolish the POPG and PIP2-induced helicity, while dual phosphorylation at these sites markedly diminished Nt17 helicity, regardless of lipid composition. The helicity of Nt17 with phosphorylation at T3 is insensitive to the membrane environment. Oxidation at M8 variably affects membrane-induced helicity, highlighting a lipid-dependent modulation of the Nt17 structure. Altogether, our findings reveal differential effects of PTMs and crosstalks between PTMs on membrane interaction and conformation of HTT. Intriguingly, the effects of phosphorylation at T3 or single acetylation at K6, K9, and K15 on Nt17 conformation in the presence of certain membranes do not mirror that observed in the absence of membranes. Our studies provide novel insights into the complex relationship between Nt17 structure, PTMs, and membrane binding.

In AF, CHA2DS2-VASc 1 subgroups did not differ for predicting risk for arterial thromboembolism at 1 y.

SOURCE CITATION: Østergaard L, Olesen JB, Petersen JK, et al. Arterial thromboembolism in patients with atrial fibrillation and CHA2DS2-VASc 1: a nationwide study. Circulation. 2024;149:764-773. 38152890.

Quantification of absolute labeling efficiency at the single-protein level.

State-of-the-art super-resolution microscopy allows researchers to spatially resolve single proteins in dense clusters. However, accurate quantification of protein organization and stoichiometries requires a general method to evaluate absolute binder labeling efficiency, which is currently unavailable. Here we introduce a universally applicable approach that uses a reference tag fused to a target protein of interest. By attaching high-affinity binders, such as antibodies or nanobodies, to both the reference tag and the target protein, and then employing DNA-barcoded sequential super-resolution imaging, we can correlate the location of the reference tag with the target molecule binder. This approach facilitates the precise quantification of labeling efficiency at the single-protein level.

Toward More Personalized Management of Device-Detected Atrial Fibrillation.

This Viewpoint discusses the need to individualize the management of subclinical atrial fibrillation according to burden (among other factors) by modeling stroke risk.

DNA glycosylases provide antiviral defence in prokaryotes.

Bacteria have adapted to phage predation by evolving a vast assortment of defence systems1. Although anti-phage immunity genes can be identified using bioinformatic tools, the discovery of novel systems is restricted to the available prokaryotic sequence data2. Here, to overcome this limitation, we infected Escherichia coli carrying a soil metagenomic DNA library3 with the lytic coliphage T4 to isolate clones carrying protective genes. Following this approach, we identified Brig1, a DNA glycosylase that excises α-glucosyl-hydroxymethylcytosine nucleobases from the bacteriophage T4 genome to generate abasic sites and inhibit viral replication. Brig1 homologues that provide immunity against T-even phages are present in multiple phage defence loci across distinct clades of bacteria. Our study highlights the benefits of screening unsequenced DNA and reveals prokaryotic DNA glycosylases as important players in the bacteria-phage arms race.

Spatial proteomics in neurons at single-protein resolution.

To understand biological processes, it is necessary to reveal the molecular heterogeneity of cells by gaining access to the location and interaction of all biomolecules. Significant advances were achieved by super-resolution microscopy, but such methods are still far from reaching the multiplexing capacity of proteomics. Here, we introduce secondary label-based unlimited multiplexed DNA-PAINT (SUM-PAINT), a high-throughput imaging method that is capable of achieving virtually unlimited multiplexing at better than 15 nm resolution. Using SUM-PAINT, we generated 30-plex single-molecule resolved datasets in neurons and adapted omics-inspired analysis for data exploration. This allowed us to reveal the complexity of synaptic heterogeneity, leading to the discovery of a distinct synapse type. We not only provide a resource for researchers, but also an integrated acquisition and analysis workflow for comprehensive spatial proteomics at single-protein resolution.

Clonal dissemination of Acinetobacter radioresistens among Humboldt penguins (Spheniscus humboldti) inhabiting a barren northern Peruvian island.

Acinetobacter spp. are often isolated from natural sources, but knowledge about their presence in wild animals is fragmented and uncomplete. The present study aimed to characterize a series of Acinetobacter radioresistens isolated from Humboldt penguins (Spheniscus humboldti). Fifteen Humboldt penguins from an inhabited northern Peruvian island were sampled. Microorganisms were identified by MALDI-TOF MS. Antibiotic susceptibility to 12 antimicrobial agents was established, and clonal relationships were determined. A representative isolate was selected for whole genome sequencing (WGS). A. radioresistens were isolated from the feces of 12 (80%) Humboldt penguins, being susceptible to all the antimicrobial agents tested, except eight cefotaxime-intermediate isolates. All A. radioresistens were clonally related. WGS showed that the isolate belonged to ST1972, the presence of two chromosomal encoded carbapenemases (blaOXA-23 and a putative subclass B3 metallo-ß-lactamase), and a series of point mutations in antibiotic-resistance related chromosomal genes, which were considered as polymorphisms. In addition, a few virulence factors, including a capsule-encoding operon, superoxide dismutases, catalases, phospholipases and a siderophore receptor were identified. The present results suggest that A. radioresistens may be a common member of the gut microbiota of Humboldt penguins, but further studies in other geographical areas are needed to establish this finding.

Dietary Concentrate Supplementation Increases Milk Production and Reduces Predicted Greenhouse Gas Emissions Intensity in Pasture-based Commercial Dairy Farms.

Controlled studies have extensively documented that concentrate supplements typically increase enteric methane (CH4) emissions and milk yield and reduce emissions per unit of milk produced and dry matter intake. However, there have been no studies conducted to determine the effect of concentrate on predicted greenhouse gas emissions from dairy farms representing the Australian pasture-based farming system. Thus, this study sought to determine how dietary concentrate supplementation affects enteric and manure CH4, and N2O of Australian pasture-based dairy farms. The Australian Dairy Carbon Calculator was used, which incorporates emission factors and methodologies used in the National Greenhouse Gas Inventory as reported to the International Panel on Climate Change. Primary data were collected and analyzed from 120 commercial farms in Australia's major dairy regions. Then the farms were divided into 4 groups based on their dietary concentrate supplementation: ≤ 1 (low; 15 farms), 1-2 (moderate;35 farms), 2-3 (high; 35 farms), and ≥ 3 (very high; 35 farms) ton (t) of concentrate dry matter per cow per year. Sources of greenhouse gas emissions were CO2 from concentrate production, enteric CH4, and manure CH4 and N2O. Total dry matter intake, milk yield, and daily enteric CH4 production (g/day) quadratically increased with concentrate level, whereas greenhouse gas emission intensity of milk production (kg CO2eq/kg fat and protein corrected milk) decreased by 14% for farms supplementing with ≥ 3 tDM/cow per year compared with those supplementing with ≤ 1 tDM/cow per year of dietary concentrate. The emissions of N2O and CH4 from manure increased quadratically and linearly, respectively, with the increasing supplementation of concentrate. Farms supplementing 2-3 tDM/cow per year showed substantial increases in gross income, gross margin, earnings before interest and tax, and net income ($/cow/year) compared with those supplementing of ≤ 1, 1-2, and ≥ 3 tDM/cow per year. In conclusion, increasing dietary concentrate supplementation for dairy cows resulted in increased milk production per cow, reduced greenhouse gas emissions per unit of milk produced, and increased income and profit. However, a comprehensive life cycle assessment study is needed to account for carbon sequestration by other farm components such as pastures and trees, which were not considered in the present study. In addition, the present study was based on modeling and did not gather ground truth information for DMI, digestibility, crude protein, and urinary and fecal N excretion. Therefore, data should be interpreted with caution, and studies gathering such information are encouraged.

A humoral stress response protects Drosophila tissues from antimicrobial peptides.

7An efficient immune system must provide protection against a broad range of pathogens without causing excessive collateral tissue damage. While immune effectors have been well characterized, we know less about the resilience mechanisms protecting the host from its own immune response. Antimicrobial peptides (AMPs) are small, cationic peptides that contribute to innate defenses by targeting negatively charged membranes of microbes. While protective against pathogens, AMPs can be cytotoxic to host cells. Here, we reveal that a family of stress-induced proteins, the Turandots, protect the Drosophila respiratory system from AMPs, increasing resilience to stress. Flies lacking Turandot genes are susceptible to environmental stresses due to AMP-induced tracheal apoptosis. Turandot proteins bind to host cell membranes and mask negatively charged phospholipids, protecting them from cationic pore-forming AMPs. Collectively, these data demonstrate that Turandot stress proteins mitigate AMP cytotoxicity to host tissues and therefore improve their efficacy.