Effects of Acid Dissociation and Ionic Solutions on the Aggregation of 2-Pyrone-4,6-dicarboxylic Acid.

The conversion of lignin can produce biomass-derived aromatic compounds such as 2-pyrone-4,6-dicarboxylic acid (PDC), which is a potential sustainable precursor of bioplastics. PDC is a pseudoaromatic dicarboxylic acid that can aggregate in aqueous solution. Aggregation depends upon PDC-PDC, PDC-water, and PDC-ion interactions that are representative of interactions in similar charged, aromatic compounds. These interactions both dictate PDC aggregation and the likelihood that PDC aggregates exhibit parallel stacking configurations that may promote PDC crystallization, which can be leveraged to separate PDC from solution. However, the interplay of interactions that drive aggregation and structure formation, and how these depend upon the charge of PDC and ionic species present in solution, remains unclear. In this work, we investigate PDC aggregation in diverse ionic solutions using all-atom molecular dynamics simulations and molecular clustering analysis. We consider ion-induced dipole interactions by using a modified Lennard-Jones nonbonded model for divalent ions in solutions. From molecular clustering analysis, we derive characteristic parameters to quantify aggregate sizes and parallel stacking configurations. We show that acid dissociation facilitates PDC aggregation in ionic solutions via ion-mediated interactions, and different ionic solutions influence both the likelihood of aggregation and the formation of parallel aggregates. In particular, we find that parallel stacking is primarily found in solutions with monovalent ions, whereas divalent ions promote larger, but less structured, aggregates. These results provide molecular-scale insight into the effects of specific ions on the aggregation of like-charged PDC molecules to inform understanding of related separation processes.

Radiofrequency catheter ablation of persistent atrial fibrillation by pulmonary vein isolation with or without left atrial posterior wall isolation: long-term outcomes of the CAPLA trial.

BACKGROUND AND AIMS: Posterior wall isolation (PWI) is commonly incorporated into catheter ablation (CA) strategies for persistent atrial fibrillation (AF) in an attempt to improve outcomes. In the CAPLA randomized study, adjunctive PWI did not improve freedom from atrial arrhythmia at 12 months compared with pulmonary vein isolation (PVI) alone. Whether additional PWI reduces arrhythmia recurrence over the longer term remains unknown. METHODS: In this multicenter, international, randomized study patients with persistent AF undergoing index CA using radiofrequency (RF) were randomized to PVI+PWI versus PVI alone. Patients underwent regular follow-up including rhythm monitoring for a minimum of 3 years post CA. AF burden at 3 years post-ablation was evaluated with either 28-day continuous ambulatory ECG monitoring, twice daily single-lead ECG or from cardiac implanted device. Evaluated endpoints included freedom from any documented atrial arrhythmia recurrence after a single procedure, AF burden, need for redo catheter ablation, rhythm at last clinical follow-up, healthcare utilisation metrics and AF-related quality of life. RESULTS: 333 of 338 (98.5%) patients (mean age 64.3±9.4 years, 23% female) completed 3-year follow-up, with 169 patients randomized to PVI+PWI and 164 patients to PVI alone. At a median of 3.62 years post-index ablation, freedom from recurrent atrial arrhythmia occurred in 59 patients (35.5%) randomized to PVI+PWI vs 68 patients (42.1%) randomized to PVI alone (HR 1.15, 95% CI 0.88-1.51, p=0.55). Median time to recurrent atrial arrhythmia was 0.53 years (IQR 0.34-1.01 years). Redo ablation was performed in 54 patients (32.0%) in the PVI+PWI group vs 49 patients (29.9%, p=0.68) in the PVI alone group. Pulmonary vein reconnection was present in 54.5% (mean number of reconnected PVs 2.2±0.9) and posterior wall reconnection in 75%. Median AF burden at 3 years was 0% in both groups (IQR 0-0.85% PVI+PWI vs 0-1.43% PVI alone, p=0.49). Sinus rhythm at final clinical follow-up was present in 85.1% with PVI+PWI vs 87.1% with PVI alone (p=0.60). Mean AF Effect On Quality-Of-Life (AFEQT) score at 3 years post-ablation was 88.0±14.8 with PVI+PWI vs 88.9±15.4 with PVI alone (p=0.63). CONCLUSIONS: In patients with persistent AF, the addition of PWI to PVI alone at index RF catheter ablation did not significantly improve freedom from atrial arrhythmia recurrence at long-term follow-up. Median AF burden remains low and AF quality of life high at 3 years with either ablation strategy.

Additive value of invasive haemodynamic assessment for predicting post-operative outcomes after Fontan.

Routine pre-Fontan cardiac catheterization remains standard practice at most centres. However, with advances in non-invasive risk assessment, an invasive haemodynamic assessment may not be necessary for all patients.Using retrospective data from patients undergoing Fontan palliation at our institution, we developed a multivariable model to predict the likelihood of a composite adverse post-operative outcome including prolonged length of stay ≥ 30 days, hospital readmission within 6 months, and death and/or transplant within 6 months. Our baseline model included non-invasive risk factors obtained from clinical history and echocardiogram. We then incrementally incorporated invasive haemodynamic data to determine if these variables improved risk prediction.Our baseline model correctly predicted favourable versus adverse post-Fontan outcomes in 118/174 (68%) patients. Covariates associated with adverse outcomes included the presence of a systemic right ventricle (adjusted adds ratio [aOR] 2.9; 95% CI 1.4, 5.8; p = 0.004), earlier surgical era (aOR 3.1 for era 1 vs 2; 95% CI 1.5, 6.5; p = 0.002), and performance of concomitant surgical procedures at the time of Fontan surgery (aOR 2.5; 95% CI 1.1, 5.0; p = 0.026). Incremental addition of invasively acquired haemodynamic data did not improve model performance or percentage of outcomes predicted.Invasively acquired haemodynamic data does not add substantially to non-invasive risk stratification in the majority of patients. Pre-Fontan catheterization may still be beneficial for angiographic evaluation of anatomy, for therapeutic intervention, and in select patients with equivocal risk stratification.

Free Energy Analysis of Peptide-Induced Pore Formation in Lipid Membranes by Bridging Atomistic and Coarse-Grained Simulations.

Antimicrobial peptides (AMPs) are attractive materials for combating the antimicrobial resistance crisis because they can kill target microbes by directly disrupting cell membranes. Although thousands of AMPs have been discovered, their molecular mechanisms of action are still poorly understood. One broad mechanism for membrane disruption is the formation of membrane-spanning hydrophilic pores which can be stabilized by AMPs. In this study, we use molecular dynamics simulations to investigate the thermodynamics of pore formation in model single-component lipid membranes in the presence of one of three AMPs: aurein 1.2, melittin and magainin 2. To overcome the general challenge of modeling long time scale membrane-related behaviors, including AMP binding, clustering, and pore formation, we develop a generalizable methodology for sampling AMP-induced pore formation. This approach involves the long equilibration of peptides around a pore created with a nucleation collective variable by performing coarse-grained simulations, then backmapping equilibrated AMP-membrane configurations to all-atom resolution. We then perform all-atom simulations to resolve free energy profiles for pore formation while accurately modeling the interplay of lipid-peptide-solvent interactions that dictate pore formation free energies. Using this approach, we quantify free energy barriers for pore formation without direct biases on peptides or whole lipids, allowing us to investigate mechanisms of pore formation for these 3 AMPs that are a consequence of unbiased peptide diffusion and clustering. Further analysis of simulation trajectories then relates variations in pore lining by AMPs, AMP-induced lipid disruptions, and salt bridges between AMPs to the observed pore formation free energies and corresponding mechanisms. This methodology and mechanistic analysis have the potential to generalize beyond the AMPs in this study to improve our understanding of pore formation by AMPs and related antimicrobial materials.

Prediction and model evaluation for space-time data.

Evaluation metrics for prediction error, model selection and model averaging on space-time data are understudied and poorly understood. The absence of independent replication makes prediction ambiguous as a concept and renders evaluation procedures developed for independent data inappropriate for most space-time prediction problems. Motivated by air pollution data collected during California wildfires in 2008, this manuscript attempts a formalization of the true prediction error associated with spatial interpolation. We investigate a variety of cross-validation (CV) procedures employing both simulations and case studies to provide insight into the nature of the estimand targeted by alternative data partition strategies. Consistent with recent best practice, we find that location-based cross-validation is appropriate for estimating spatial interpolation error as in our analysis of the California wildfire data. Interestingly, commonly held notions of bias-variance trade-off of CV fold size do not trivially apply to dependent data, and we recommend leave-one-location-out (LOLO) CV as the preferred prediction error metric for spatial interpolation.

Salvianolic acid B inhibits thrombosis and directly blocks the thrombin catalytic site.

Background: Salvianolic acid B (SAB) is a major component of Salvia miltiorrhiza root (Danshen), widely used in East/Southeast Asia for centuries to treat cardiovascular diseases. Danshen depside salt, 85% of which is made up of SAB, is approved in China to treat chronic angina. Although clinical observations suggest that Danshen extracts inhibited arterial and venous thrombosis, the exact mechanism has not been adequately elucidated. Objective: To delineate the antithrombotic mechanisms of SAB. Methods: We applied platelet aggregation and coagulation assays, perfusion chambers, and intravital microscopy models. The inhibition kinetics and binding affinity of SAB to thrombin are measured by thrombin enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. We used molecular in silico docking models to predict the interactions of SAB with thrombin. Results: SAB dose-dependently inhibited platelet activation and aggregation induced by thrombin. SAB also reduced platelet aggregation induced by adenosine diphosphate and collagen. SAB attenuated blood coagulation by modifying fibrin network structures and significantly decreased thrombus formation in mouse cremaster arterioles and perfusion chambers. The direct SAB-thrombin interaction was confirmed by enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. Interestingly, SAB shares key structural similarities with the trisubstituted benzimidazole class of thrombin inhibitors, such as dabigatran. Molecular docking models predicted the binding of SAB to the thrombin active site. Conclusion: Our data established SAB as the first herb-derived direct thrombin catalytic site inhibitor, suppressing thrombosis through both thrombin-dependent and thrombin-independent pathways. Purified SAB may be a cost-effective agent for treating arterial and deep vein thrombosis.

Effects of exposure to snus marketing with versus without modified risk tobacco product claims on snus use intention and perceived harm among young adults.

BACKGROUND: We tested whether snus marketing with modified risk tobacco product (MRTP) claims: (a) promotes accurate knowledge about snus's health effects in young adults and (b) encourages use intentions in only those who use combustible tobacco without attracting other young adult populations. METHODS: A randomised between-subjects experiment was embedded in a 2020 web survey of participants from Los Angeles (aged 19-23 years). Participants viewed mass-marketed snus advertising materials with (n=1212) vs without (n=1225) US Food and Drug Administration-authorised MRTP claims. After advertising exposure, snus use intention and perceptions of snus harms relative to cigarettes or e-cigarettes were measured. RESULTS: Advertisements with versus without MRTP claims did not affect snus use intention (18.0% vs 19.4%) but produced a higher prevalence of perceptions that snus was less harmful than cigarettes (12.6% vs 9.1%; p=0.007) and e-cigarettes (8.0% vs 5.8%; p=0.04). MRTP claim exposure effects did not differ by past 30-day e-cigarette or combustible tobacco use. Snus use intentions after marketing exposure, collapsed across MRTP claim conditions, were higher in those who did versus did not report past 30-day use of e-cigarettes (38.4% vs 14.3%; adjusted OR (95% CI) 2.95 (2.28 to 3.81); p<0.001) or combustible tobacco (44.0% vs 16.2%; adjusted OR (95% CI) 2.26 (1.62 to 3.16); p<0.001). CONCLUSION: Although some young adults who vape or smoke may have snus use intentions, snus MRTP claims might not affect young adults' snus use intentions, regardless of whether they vape/smoke. MRTP claims might modestly increase the accuracy of perceived harms of snus relative to cigarettes while also slightly causing unsubstantiated perceptions of lower harm than e-cigarettes.

Heparin-Induced Thrombocytopenia (HIT) in the Direct Oral Anticoagulants (DOAC) Era.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is an uncommon complication of heparin therapy with significant risk for severe morbidity and mortality. We investigated the role and outcome of direct oral anticoagulants (DOACs) for the management of HIT. METHODS: After institutional review board (IRB) approval, a retrospective review was performed identifying all patients with positive HIT serotonin-release assays between 2020 and 2022 at two hospitals. The demographic and clinical variables were collected as follows: initial anticoagulant, dosing and indication, interval before onset of HIT, thrombotic complications, platelet nadir and recovery, direct thrombin inhibitor (DTI) and DOAC usage, and clinical outcomes. RESULTS: 15 patients were included in the study. 8 underwent a vascular procedure, 3 had cardiac surgery, 1 patient had both and was included in both groups, and 5 patients had either noncardiac, nonvascular surgery, or no surgery. 14 patients received unfractionated heparin (93% with therapeutic dosing), and 1 received prophylactic enoxaparin prior to diagnosis of HIT. The average time to diagnosis of HIT was 10.77 days after initial anticoagulation. In-hospital mortality was 27%, related to Covid-19 infection (3/4) and intracranial hemorrhage (1/4). 40% developed thrombosis (67% venous, 33% arterial) after the diagnosis of HIT. 8/11 survivors were discharged on a DOAC. With DOAC therapy, platelet counts rebounded to an average of 265K ( ± 104.6 K) within an average of 2.3 days and 364K ( ± 273.9 K) within 30 days after initiation of a DOAC. No recurrent thrombosis occurred after DOAC administration and only one patient had persistent thrombocytopenia within 30 days. CONCLUSIONS: Mortality and thrombosis (arterial and venous) are common complications in patients diagnosed with HIT. In patients who survive to discharge, DOACs are the most common discharge antithrombotic agent, with low rates of recurrent thrombosis and thrombocytopenia.

In vitro analysis of tantalum-containing mesoporous bioactive glass fibres for haemostasis.

Haemorrhage is the leading cause of battlefield deaths and second most common cause for civilian mortality worldwide. Biomaterials-based haemostatic agents are used to aid in bleeding stoppage; mesoporous bioactive glasses (MBGs) are candidates for haemostasis. Previously made Tantalum-containing MBG (Ta-MBG) powders' compositions were fabricated as electrospun fibres for haemostatic applications in the present study. The fibres were fabricated to address the challenges associated with the powder form: difficult to compress without gauze, getting washed away in profuse bleeding, generating dust in the surgical environment, and forming thick callus-difficult to remove for surgeons and painful for patients. Ta-MBGs were based on (80-x)SiO2-15CaO-5P2O5-xTa2O5 mol% compositions with x = 0 (0Ta), 0.5 (0.5Ta), 1 (1Ta), and 5 (5Ta) mol%. The present study details the fibres' in vitro analyses, elucidating their cytotoxic effects, and haemostatic capabilities and relating these observations to fibre chemistry and previously fabricated powders of the same glasses. As expected, when Ta addition is increased at the expense of silica, a new FTIR peak (non-bridging oxygen-silicon, Si-NBO) develops and Si-O-Si peaks become wider. Compared to 0Ta and 1Ta fibres, 0.5Ta show Si-O peaks with reduced intensity. The fibres had a weaker intensity of Si-NBO peaks and release fewer ions than powders. A reduced ion profile provides fibres with a stable matrix for clot formation. The ion release profile for 1Ta and 5Ta fibres was significantly lower than 0Ta and 0.5Ta fibres. Ta-MBGs were not found to be cytotoxic to primary rat fibroblasts using a methyl thiazolyl tetrazolium (MTT) assay. Furthermore, a modified activated partial thromboplastin time assay analysing the fibrin absorbance showed that the absorption increases from physiological clotting < 0Ta < 0.5Ta < 5Ta < commercial haemostat, Surgical SNoWTM, Ethicon, USA < 1Ta. Higher absorption signifies a stronger clot. It is concluded that Ta-MBG fibres can provide stable matrix for clot formation and 1Ta can potentially enhance clotting best among other Ta-MBGs.

Lumbar Drain Use during Middle Fossa Approaches for Nonneoplastic Pathology of the Skull Base.

Introduction The middle fossa craniotomy (MFCs) is commonly utilized for spontaneous cerebrospinal fluid (CSF) leaks, encephaloceles, and superior semicircular canal dehiscence (SSCD). This study compares postoperative outcomes of MFCs with and without LD use. Methods A retrospective cohort study of adults over the age of 18 years presenting for the repair of nonneoplastic CSF leak, encephalocele, or SSCD via MFC from 2009 to 2021 was conducted. The main exposure of interest was the placement of an LD. The primary outcome was the presence of postoperative complications (acute/delayed neurologic deficit, meningitis, intracranial hemorrhage, and stroke). Secondary outcomes included operating room (OR) time, length of stay, recurrence, and need for reoperation. Results In total, 172 patients were included, 96 of whom received an LD and 76 who did not. Patients not receiving an LD were more likely to receive intraoperative mannitol ( n = 24, 31.6% vs. n = 16, 16.7%, p = 0.02). On univariate logistic regression, LD placement did not influence overall postoperative complications (OR: 0.38, 95% confidence interval [CI]: 0.05-2.02, p = 0.28), CSF leak recurrence (OR: 0.75, 95% CI: 0.25-2.29, p = 0.61), or need for reoperation (OR: 1.47, 95% CI: 0.48-4.96, p = 0.51). While OR time was shorter for patients not receiving LD (349 ± 71 vs. 372 ± 85 minutes), this difference was not statistically significant ( p = 0.07). Conclusion No difference in postoperative outcomes was observed in patients who had an intraoperative LD placed compared to those without LD. Operative times were increased in the LD cohort, but this difference was not statistically significant. Given the similar outcomes, we conclude that LD is not necessary to facilitate safe MCF for nonneoplastic skull base pathologies.

Nanocrystal Assemblies: Current Advances and Open Problems.

We explore the potential of nanocrystals (a term used equivalently to nanoparticles) as building blocks for nanomaterials, and the current advances and open challenges for fundamental science developments and applications. Nanocrystal assemblies are inherently multiscale, and the generation of revolutionary material properties requires a precise understanding of the relationship between structure and function, the former being determined by classical effects and the latter often by quantum effects. With an emphasis on theory and computation, we discuss challenges that hamper current assembly strategies and to what extent nanocrystal assemblies represent thermodynamic equilibrium or kinetically trapped metastable states. We also examine dynamic effects and optimization of assembly protocols. Finally, we discuss promising material functions and examples of their realization with nanocrystal assemblies.

Long-Chain Lipids Facilitate Insertion of Large Nanoparticles into Membranes of Small Unilamellar Vesicles.

Insertion of hydrophobic nanoparticles into phospholipid bilayers is limited to small particles that can incorporate into a hydrophobic membrane core between two lipid leaflets. Incorporation of nanoparticles above this size limit requires the development of challenging surface engineering methodologies. In principle, increasing the long-chain lipid component in the lipid mixture should facilitate incorporation of larger nanoparticles. Here, we explore the effect of incorporating very long phospholipids (C24:1) into small unilamellar vesicles on the membrane insertion efficiency of hydrophobic nanoparticles that are 5-11 nm in diameter. To this end, we improve an existing vesicle preparation protocol and utilized cryogenic electron microscopy imaging to examine the mode of interaction and evaluate the insertion efficiency of membrane-inserted nanoparticles. We also perform classical coarse-grained molecular dynamics simulations to identify changes in lipid membrane structural properties that may increase insertion efficiency. Our results indicate that long-chain lipids increase the insertion efficiency by preferentially accumulating near membrane-inserted nanoparticles to reduce the thermodynamically unfavorable disruption of the membrane.

Importance of Various E-Cigarette Device and E-Liquid Characteristics by Smoking Status among Young Adults Who Vape.

BACKGROUND: E-cigarette product characteristics are known to influence appeal among young adults. Understanding which characteristics appeal to individuals with (vs. without) a history of combusted tobacco use is essential for developing effective tobacco control policies. METHODS: Anonymous, self-report data were collected from young adults (18-30 years) who had used e-cigarettes in the past 30 days (n = 295) online via Prolific from September-October 2019. Using a visual analogue scale (range: 0-100), participants rated the importance of ten e-cigarette device and nine e-liquid characteristics. Adjusted linear regression models were used to evaluate the association of combusted tobacco use status (never, former, current) with mean rating scores for each of the nineteen characteristics. RESULTS: The most important e-cigarette device characteristics were price (Mean = 81.1; [SD = 17.9]), size (Mean = 75.5 [SD = 20.9]), and hit strength (Mean = 73.8 [SD = 20.4]) while the most important e-liquid characteristics were flavor (M = 85.1 [SD = 16.3]), price (M = 80.9 [SD = 18.4]), and nicotine level (M = 77.8 [18.9]). Differences by combusted tobacco use status were observed for device brand, temperature/voltage, customizability, color, and popularity, with the highest ratings generally observed among those concurrently using combustible tobacco products. For e-liquids, differences by use status were observed for flavor, price, and bottle type. Notably, those concurrently using combusted products rated flavor as less important than those with no history of combustible tobacco use (B=-5.01[95%CI=-9.97, -0.05]). CONCLUSIONS: The self-rated importance of e-cigarette device and e-liquid attributes varies by combustible tobacco use status among young adults which may be used to inform regulatory decisions regarding e-cigarette product characteristics.

Resident Salary Compared to Living Wages at United States Training Institutions.

OBJECTIVE: To compare living wages and salaries at US residency programs. SUMMARY BACKGROUND DATA: It is unknown how resident salary compares to living wages across the United States (US). METHODS: Cross-sectional analysis of publicly available resident salary affordability from training centers with post-graduate-year (PGY)-1 through PGY-7 resident compensation for 2022-2023 was compared with the Massachusetts Institute of Technology (MIT) Living-Wage Calculator. Resident salary to living wage ratios were calculated using PGY-4 salary for each family composition. Univariate and multivariable analysis of PGY-4 salary affordability was performed, accounting for proportion of expected living wages to taxes, transportation, housing, healthcare, childcare, and food, as well as unionization and state income-tax. RESULTS: 118 residency programs, representing over 60% of US trainees, were included, 20 (17%) of which were unionized. Single-parent families were unable to earn a living wage until PGY-7. Residents with 1 child in 2-adult (single-income) and 2-adult (dual-income) families earn below living wages until PGY-5 and PGY-3, respectively. Residents with more than 1 child never earn a living wage. Multivariable regression analysis using PGY-4 salary: living wage ratios in single-child, 2-parent homes showed food expense and unionization status were consistent predictors of affordability. Unionization was associated with lower affordability pre-stipend, almost equivalent affordability post-stipend, and lower affordability post-stipend and union dues. CONCLUSIONS: Resident salaries often preclude residents with children from earning a living wage. Unionization is not associated with increased resident affordability in this cross-sectional analysis. All annual reimbursement data should be centrally compiled, and additional stipends should be considered for residents with children.

Velociraptor: Cross-Platform Quantitative Search Using Hallmark Cell Features.

A key challenge for single cell discovery analysis is to identify new cell types, describe them quantitatively, and seek these novel cells in new studies often using a different platform. Over the last decade, tools were developed to address identification and quantitative description of cells in human tissues and tumors. However, automated validation of populations at the single cell level has struggled due to the cytometry field's reliance on hierarchical, ordered use of features and on platform-specific rules for data processing and analysis. Here we present Velociraptor, a workflow that implements Marker Enrichment Modeling in three cross-platform modules: 1) identification of cells specific to disease states, 2) description of hallmark features for each cell and population, and 3) searching for cells matching one or more hallmark feature sets in a new dataset. A key advance is that Velociraptor registers cells between datasets, including between flow cytometry and quantitative imaging using different, overlapping feature sets. Four datasets were used to challenge Velociraptor and reveal new biological insights. Working at the individual sample level, Velociraptor tracked the abundance of clinically significant glioblastoma brain tumor cell subsets and characterized the cells that predominate in recurrent tumors as a close match for rare, negative prognostic cells originally observed in matched pre-treatment tumors. In patients with inborn errors of immunity, Velociraptor identified genotype-specific cells associated with GATA2 haploinsufficiency. Finally, in cross-platform analysis of immune cells in multiplex imaging of breast cancer, Velociraptor sought and correctly identified memory T cell subsets in tumors. Different phenotypic descriptions generated by algorithms or humans were shown to be effective as search inputs, indicating that cell identity need not be described in terms of per-feature cutoffs or strict hierarchical analyses. Velociraptor thus identifies cells based on hallmark feature sets, such as protein expression signatures, and works effectively with data from multiple sources, including suspension flow cytometry, imaging, and search text based on known or theoretical cell features.

IL-8 Instructs Macrophage Identity in Lateral Ventricle Contacting Glioblastoma.

Adult IDH-wildtype glioblastoma (GBM) is a highly aggressive brain tumor with no established immunotherapy or targeted therapy. Recently, CD32+ HLA-DRhi macrophages were shown to have displaced resident microglia in GBM tumors that contact the lateral ventricle stem cell niche. Since these lateral ventricle contacting GBM tumors have especially poor outcomes, identifying the origin and role of these CD32+ macrophages is likely critical to developing successful GBM immunotherapies. Here, we identify these CD32+ cells as M_IL-8 macrophages and establish that IL-8 is sufficient and necessary for tumor cells to instruct healthy macrophages into CD32+ M_IL-8 M2 macrophages. In ex vivo experiments with conditioned medium from primary human tumor cells, inhibitory antibodies to IL-8 blocked the generation of CD32+ M_IL-8 cells. Finally, using a set of 73 GBM tumors, IL-8 protein is shown to be present in GBM tumor cells in vivo and especially common in tumors contacting the lateral ventricle. These results provide a mechanistic origin for CD32+ macrophages that predominate in the microenvironment of the most aggressive GBM tumors. IL-8 and CD32+ macrophages should now be explored as targets in combination with GBM immunotherapies, especially for patients whose tumors present with radiographic contact with the ventricular-subventricular zone stem cell niche.

Surgical Modulation of Pulmonary Artery Shear Stress: A Patient-Specific CFD Analysis of the Norwood Procedure.

PURPOSR: This study created 3D CFD models of the Norwood procedure for hypoplastic left heart syndrome (HLHS) using standard angiography and echocardiogram data to investigate the impact of shunt characteristics on pulmonary artery (PA) hemodynamics. Leveraging routine clinical data offers advantages such as availability and cost-effectiveness without subjecting patients to additional invasive procedures. METHODS: Patient-specific geometries of the intrathoracic arteries of two Norwood patients were generated from biplane cineangiograms. "Virtual surgery" was then performed to simulate the hemodynamics of alternative PA shunt configurations, including shunt type (modified Blalock-Thomas-Taussig shunt (mBTTS) vs. right ventricle-to-pulmonary artery shunt (RVPAS)), shunt diameter, and pulmonary artery anastomosis angle. Left-right pulmonary flow differential, Qp/Qs, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) were evaluated. RESULTS: There was strong agreement between clinically measured data and CFD model output throughout the patient-specific models. Geometries with a RVPAS tended toward more balanced left-right pulmonary flow, lower Qp/Qs, and greater TAWSS and OSI than models with a mBTTS. For both shunt types, larger shunts resulted in a higher Qp/Qs and higher TAWSS, with minimal effect on OSI. Low TAWSS areas correlated with regions of low flow and changing the PA-shunt anastomosis angle to face toward low TAWSS regions increased TAWSS. CONCLUSION: Excellent correlation between clinically measured and CFD model data shows that 3D CFD models of HLHS Norwood can be developed using standard angiography and echocardiographic data. The CFD analysis also revealed consistent changes in PA TAWSS, flow differential, and OSI as a function of shunt characteristics.

Ligand Lipophilicity Determines Molecular Mechanisms of Nanoparticle Adsorption to Lipid Bilayers.

The interactions of ligand-functionalized nanoparticles with the cell membrane affect cellular uptake, cytotoxicity, and related behaviors, but relating these interactions to ligand properties remains challenging. In this work, we perform coarse-grained molecular dynamics simulations to study how the adsorption of ligand-functionalized cationic gold nanoparticles (NPs) to a single-component lipid bilayer (as a model cell membrane) is influenced by ligand end group lipophilicity. A set of 2 nm diameter NPs, each coated with a monolayer of organic ligands that differ only in their end groups, was simulated to mimic NPs recently studied experimentally. Metadynamics calculations were performed to determine key features of the free energy landscape for adsorption as a function of the distance of the NP from the bilayer and the number of NP-lipid contacts. These simulations revealed that NP adsorption is thermodynamically favorable for all NPs due to the extraction of lipids from the bilayer and into the NP monolayer. To resolve ligand-dependent differences in adsorption behavior, string method calculations were performed to compute minimum free energy pathways for adsorption. These calculations revealed a surprising nonmonotonic dependence of the free energy barrier for adsorption on ligand end group lipophilicity. Large free energy barriers are predicted for the least lipophilic end groups because favorable NP-lipid contacts are initiated only through the unfavorable protrusion of lipid tail groups out of the bilayer. The smallest free energy barriers are predicted for end groups of intermediate lipophilicity which promote NP-lipid contacts by intercalating within the bilayer. Unexpectedly, large free energy barriers are also predicted for the most lipophilic end groups which remain sequestered within the ligand monolayer rather than intercalating within the bilayer. These trends are broadly in agreement with past experimental measurements and reveal how subtle variations in ligand lipophilicity dictate adsorption mechanisms and associated kinetics by influencing the interplay of lipid-ligand interactions.