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1.
J Am Chem Soc ; 146(20): 13962-13973, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38727611

RESUMO

Dimeric complexes composed of d8 square planar metal centers and rigid bridging ligands provide model systems to understand the interplay between attractive dispersion forces and steric strain in order to assist the development of reliable methods to model metal dimer complexes more broadly. [Ir2 (dimen)4]2+ (dimen = para-diisocyanomenthane) presents a unique case study for such phenomena, as distortions of the optimal structure of a ligand with limited conformational flexibility counteract the attractive dispersive forces from the metal and ligand to yield a complex with two ground state deformational isomers. Here, we use ultrafast X-ray solution scattering (XSS) and optical transient absorption spectroscopy (OTAS) to reveal the nature of the equilibrium distribution and the exchange rate between the deformational isomers. The two ground state isomers have spectrally distinct electronic excitations that enable the selective excitation of one isomer or the other using a femtosecond duration pulse of visible light. We then track the dynamics of the nonequilibrium depletion of the electronic ground state population─often termed the ground state hole─with ultrafast XSS and OTAS, revealing a restoration of the ground state equilibrium in 2.3 ps. This combined experimental and theoretical study provides a critical test of various density functional approximations in the description of bridged d8-d8 metal complexes. The results show that density functional theory calculations can reproduce the primary experimental observations if dispersion interactions are added, and a hybrid functional, which includes exact exchange, is used.

2.
Arterioscler Thromb Vasc Biol ; 44(5): 1144-1155, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38511326

RESUMO

BACKGROUND: Elevated apoB-containing lipoproteins (=remnants+LDLs [low-density lipoproteins]) are a major risk factor for atherosclerotic cardiovascular disease, including peripheral artery disease (PAD) and myocardial infarction. We tested the hypothesis that remnants and LDL both explain part of the increased risk of PAD conferred by elevated apoB-containing lipoproteins. For comparison, we also studied the risk of chronic limb-threatening ischemia and myocardial infarction. METHODS: apoB, remnant cholesterol, and LDL cholesterol were measured in 93 461 individuals without statin use at baseline from the Copenhagen General Population Study (2003-2015). During up to 15 years of follow-up, 1207 had PAD, 552 had chronic limb-threatening ischemia, and 2022 had myocardial infarction in the Danish National Patient Registry. Remnant and LDL cholesterol were calculated from a standard lipid profile. Remnant and LDL particle counts were additionally measured with nuclear magnetic resonance spectroscopy in 25 347 of the individuals. Results were replicated in 302 167 individuals without statin use from the UK Biobank (2004-2010). RESULTS: In the Copenhagen General Population Study, multivariable adjusted hazard ratios for risk of PAD per 1 mmol/L (39 mg/dL) increment in remnant and LDL cholesterol were 1.9 (95% CI, 1.5-2.4) and 1.1 (95% CI, 1.0-1.2), respectively; corresponding results in the UK Biobank were 1.7 (95% CI, 1.4-2.1) and 0.9 (95% CI, 0.9-1.0), respectively. In the association from elevated apoB to increased risk of PAD, remnant and LDL cholesterol explained 73% (32%-100%) and 8% (0%-46%), respectively; corresponding results were 63% (30%-100%) and 0% (0%-33%) for risk of chronic limb-threatening ischemia and 41% (27%-55%) and 54% (38%-70%) for risk of myocardial infarction; results for remnant and LDL particle counts corroborated these findings. CONCLUSIONS: PAD risk conferred by elevated apoB-containing lipoproteins was explained mainly by elevated remnants, while myocardial infarction risk was explained by both elevated remnants and LDL.


Assuntos
Apolipoproteína B-100 , Biomarcadores , LDL-Colesterol , Colesterol , Lipoproteínas , Doença Arterial Periférica , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Apolipoproteína B-100/sangue , Biomarcadores/sangue , Colesterol/sangue , LDL-Colesterol/sangue , Dinamarca/epidemiologia , Isquemia/sangue , Isquemia/epidemiologia , Isquemia/diagnóstico , Infarto do Miocárdio/epidemiologia , Infarto do Miocárdio/sangue , Infarto do Miocárdio/diagnóstico , Doença Arterial Periférica/epidemiologia , Doença Arterial Periférica/sangue , Doença Arterial Periférica/diagnóstico , Estudos Prospectivos , Sistema de Registros , Medição de Risco , Fatores de Risco , Fatores de Tempo , Triglicerídeos
3.
Nat Chem ; 16(5): 735-740, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38374454

RESUMO

The inimitable electronic structures of the lanthanide (Ln) ions are key to advanced materials and technologies involving these elements. The trivalent ions are ubiquitous and are used much more widely than the divalent and tetravalent analogues, which possess vastly different optical and magnetic properties. Hence, alteration of the valence electron count by external stimuli can lead to dramatic changes in materials properties. Compounds exhibiting a temperature-induced complete Ln(III) ⇄ Ln(II) switch, referred to as a valence tautomeric (VT) transition, are rare. Here we present an abrupt and hysteretic VT transition in a lanthanide-based coordination polymer, SmI2(pyrazine)3, driven by the interconversion of Sm(II)-pyrazine(0) and Sm(III)-pyrazine(·-) redox pairs. Alloying SmI2(pyrazine)3 with Yb(II) yields isomorphous Sm1-xYbxI2(pyrazine)3 solid solutions with VT transition critical temperatures ranging widely from 200 K to ∼50 K at ambient pressure. These findings demonstrate a simple strategy to realize thermally switchable magnetic materials with chemically tunable transition temperatures.

4.
Nat Commun ; 15(1): 1177, 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38331922

RESUMO

Acquiring spatial control of nanoscopic metal clusters is central to their function as efficient multi-electron catalysts. However, dispersing metal clusters on surfaces or in porous hosts is accompanied by an intrinsic heterogeneity that hampers detailed understanding of the chemical structure and its relation to reactivities. Tethering pre-assembled molecular metal clusters into polymeric, crystalline 2D or 3D networks constitutes an unproven approach to realizing ordered arrays of chemically well-defined metal clusters. Herein, we report the facile synthesis of a {Pd3} cluster-based organometallic framework from a molecular triangulo-Pd3(CNXyl)6 (Xyl = xylyl; Pd3) cluster under chemically mild conditions. The formally zero-valent Pd3 cluster readily engages in a complete ligand exchange when exposed to a similar, ditopic isocyanide ligand, resulting in polymerization into a 2D coordination network (Pd3-MOF). The structure of Pd3-MOF could be unambiguously determined by continuous rotation 3D electron diffraction (3D-ED) experiments to a resolution of ~1.0 Å (>99% completeness), showcasing the applicability of 3D-ED to nanocrystalline, organometallic polymers. Pd3-MOF displays Pd03 cluster nodes, which possess significant thermal and aerobic stability, and activity towards hydrogenation catalysis. Importantly, the realization of Pd3-MOF paves the way for the exploitation of metal clusters as building blocks for rigidly interlocked metal nanoparticles at the molecular limit.

5.
Artigo em Inglês | MEDLINE | ID: mdl-37878425

RESUMO

Spherical diverging acoustic lenses mounted on flat 2-D row-column-addressed (RCA) ultrasound transducers have shown the potential to extend the field of view (FOV) from a rectilinear to a curvilinear volume region and, thereby, enable 3-D imaging of large organs. Such lenses are usually designed for small aperture low-frequency transducers, which have limited resolution. Moreover, they are made of off-the-shelf pieces of materials, which leaves no room for optimization. We hypothesize that acoustic lenses can be designed to fit high-resolution transducers, and they can be fabricated in a fast, cost-effective, and flexible manner using a combination of 3-D printing and casting or computer numerical control (CNC) machining techniques. These lenses should increase the FOV of the array while preserving the image quality. In this work, such lenses are made in concave, convex, and compound spherical shapes and from thermoplastics and thermosetting polymers. Polymethylpentene (TPX), polystyrene (PS), polypropylene (PP), polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), and room-temperature-vulcanizing (RTV) silicone diverging lenses have been fabricated and mounted on a 128 + 128 6-MHz RCA transducer. The performances of the lenses have been assessed and compared in terms of FOV, signal-to-noise ratio (SNR), bandwidth, and potential artifacts. The largest FOV (24.0.) is obtained with a 42.64-mm radius PMMA-RTV compound lens, which maintains a decent fractional bandwidth (53%) and SNR at 6 MHz (.9.1-dB amplitude drop compared with the unlensed transducer). The simple PMMA TPX, PS, PP, PDMS, and RTV lenses provide an FOV of 12.2°, 6.3°, 8.1°, 11.7°, 0.6°, and 10.4°; a fractional bandwidth of 97%, 46%, 103%, 46%, 97%, 53%, and 49%; and an amplitude drop of -5.2, -4.4, -2.8, -15.4, -6.0, and -1.8 dB, respectively. This work demonstrates that thermoplastics are suitable materials for fabricating low-attenuation convex diverging lenses for large-aperture, high-frequency 2-D transducers. This is highly desired to achieve high-resolution volumetric imaging of large organs.

6.
Nat Commun ; 14(1): 8198, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-38081813

RESUMO

Antibiotic resistance of bacteria is considered one of the most alarming developments in modern medicine. While varied pathways for bacteria acquiring antibiotic resistance have been identified, there still are open questions concerning the mechanisms underlying resistance. Here, we show that alpha phenol-soluble modulins (PSMαs), functional bacterial amyloids secreted by Staphylococcus aureus, catalyze hydrolysis of ß-lactams, a prominent class of antibiotic compounds. Specifically, we show that PSMα2 and, particularly, PSMα3 catalyze hydrolysis of the amide-like bond of the four membered ß-lactam ring of nitrocefin, an antibiotic ß-lactam surrogate. Examination of the catalytic activities of several PSMα3 variants allowed mapping of the active sites on the amyloid fibrils' surface, specifically underscoring the key roles of the cross-α fibril organization, and the combined electrostatic and nucleophilic functions of the lysine arrays. Molecular dynamics simulations further illuminate the structural features of ß-lactam association upon the fibril surface. Complementary experimental data underscore the generality of the functional amyloid-mediated catalytic phenomenon, demonstrating hydrolysis of clinically employed ß-lactams by PSMα3 fibrils, and illustrating antibiotic degradation in actual S. aureus biofilms and live bacteria environments. Overall, this study unveils functional amyloids as catalytic agents inducing degradation of ß-lactam antibiotics, underlying possible antibiotic resistance mechanisms associated with bacterial biofilms.


Assuntos
Infecções Estafilocócicas , Staphylococcus aureus , Humanos , Antibióticos beta Lactam , Antibacterianos/farmacologia , Antibacterianos/metabolismo , Monobactamas/metabolismo , beta-Lactamas/farmacologia , beta-Lactamas/metabolismo , Infecções Estafilocócicas/microbiologia , Bactérias
7.
Crit Care ; 27(1): 389, 2023 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-37814277

RESUMO

BACKGROUND: Low levels of high-density lipoprotein (HDL) cholesterol have been associated with higher rates and severity of infection. Alterations in inflammatory mediators and infection are associated with alterations in HDL cholesterol. It is unknown whether the association between HDL and infection is present for all particle sizes, and whether the observed associations are confounded by IL-6 signalling. METHODS: In the UK Biobank, ~ 270,000 individuals have data on HDL subclasses derived from nuclear magnetic resonance analysis. We estimated the association of particle count of total HDL and HDL subclasses (small, medium, large, and extra-large HDL) with sepsis, sepsis-related death, and critical care admission in a Cox regression model. We subsequently utilised genetic data from UK Biobank and FinnGen to perform Mendelian randomisation (MR) of each HDL subclass and sepsis to test for a causal relationship. Finally, we explored the role of IL-6 signalling as a potential causal driver of changes in HDL subclasses. RESULTS: In observational analyses, higher particle count of small HDL was associated with protection from sepsis (Hazard ratio, HR 0.80; 95% CI 0.74-0.86, p = 4 × 10-9 comparing Quartile 4, highest quartile of HDL to Quartile 1, lowest quartile of HDL), sepsis-related death (HR 0.80; 95% CI 0.74-0.86, p = 2 × 10-4), and critical care admission with sepsis (HR 0.72 95% CI 0.60-0.85, p = 2 × 10-4). Parallel associations with other HDL subclasses were likely driven by changes in the small HDL compartment. MR analyses did not strongly support causality of small HDL particle count on sepsis incidence (Odds ratio, OR 0.98; 95% CI 0.89-1.07, p = 0.6) or death (OR 0.94, 95% CI 0.75-1.17, p = 0.56), although the estimate on critical care admission with sepsis supported protection (OR 0.73, 95% CI 0.57-0.95, p = 0.02). Bidirectional MR analyses suggested that increased IL-6 signalling was associated with reductions in both small (beta on small HDL particle count - 0.16, 95% CI - 0.10 to - 0.21 per natural log change in SD-scaled CRP, p = 9 × 10-8).and total HDL particle count (beta - 0.13, 95% CI - 0.09 to - 0.17, p = 7 × 10-10), but that the reverse effect of HDL on IL-6 signalling was largely null. CONCLUSIONS: Low number of small HDL particles are associated with increased hazard of sepsis, sepsis-related death, and sepsis-related critical care admission. However, genetic analyses did not strongly support this as causal. Instead, we demonstrate that increased IL-6 signalling, which is known to alter infection risk, could confound associations with reduced HDL particle count, and suggest this may explain part of the observed association between (small) HDL particle count and sepsis.


Assuntos
Interleucina-6 , Sepse , Humanos , HDL-Colesterol , Espectroscopia de Ressonância Magnética , Modelos de Riscos Proporcionais
8.
ACS Sens ; 8(9): 3478-3486, 2023 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-37669038

RESUMO

The detection of methane and carbon dioxide is of growing importance due to their negative impact on global warming. This is true for both environmental monitoring and leak detection in industrial processes. Although solid-state sensors are technologically mature, they have limitations that prohibit their use in certain situations, e.g., explosive atmospheres. Thus, there is a need to develop new types of sensor materials. Herein, we demonstrate a simple, low-cost, metal-organic framework (MOF)-based gas leak detection sensor. The system is based on gravimetric sensing by using a quartz crystal microbalance. The quartz crystal is functionalized by layer-by-layer growth of a thin metal-organic framework film. This film shows selective uptake of methane or carbon dioxide under atmospheric conditions. The hardware has low cost, simple operation, and theoretically high sensitivity. Overall, the sensor is characterized by simplicity and high robustness. Furthermore, by exploiting the different adsorption kinetics as measured by multiple harmonic analyses, it is possible to discriminate whether the response is due to methane or carbon dioxide. In summary, we demonstrate data relevant toward new applications of metal-organic frameworks and microporous hybrid materials in sensing.


Assuntos
Dióxido de Carbono , Estruturas Metalorgânicas , Temperatura , Adsorção , Metano
9.
Nat Commun ; 14(1): 5731, 2023 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-37723164

RESUMO

The amyloid aggregation of α-synuclein (αS), related to Parkinson's disease, can be catalyzed by lipid membranes. Despite the importance of lipid surfaces, the 3D-structure and orientation of lipid-bound αS is still not known in detail. Here, we report interface-specific vibrational sum-frequency generation (VSFG) experiments that reveal how monomeric αS binds to an anionic lipid interface over a large range of αS-lipid ratios. To interpret the experimental data, we present a frame-selection method ("ViscaSelect") in which out-of-equilibrium molecular dynamics simulations are used to generate structural hypotheses that are compared to experimental amide-I spectra via excitonic spectral calculations. At low and physiological αS concentrations, we derive flat-lying helical structures as previously reported. However, at elevated and potentially disease-related concentrations, a transition to interface-protruding αS structures occurs. Such an upright conformation promotes lateral interactions between αS monomers and may explain how lipid membranes catalyze the formation of αS amyloids at elevated protein concentrations.


Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , Amidas , Proteínas Amiloidogênicas , Lipídeos
10.
Diabetologia ; 66(12): 2238-2249, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37776347

RESUMO

AIMS/HYPOTHESIS: Elevated remnant cholesterol is observationally and causally associated with increased risk of atherosclerotic cardiovascular disease (ASCVD) in the general population. This association is not well studied in individuals with diabetes, who are often included in clinical trials of remnant cholesterol-lowering therapy. We tested the hypothesis that elevated remnant cholesterol is associated with increased risk of ASCVD in individuals with diabetes. We also explored the fraction of excess risk conferred by diabetes which can be explained by elevated remnant cholesterol. METHODS: We included 4569 white Danish individuals with diabetes (58% statin users) nested within the Copenhagen General Population Study (2003-2015). The ASCVDs peripheral artery disease, myocardial infarction and ischaemic stroke were extracted from national Danish health registries without losses to follow-up. Remnant cholesterol was calculated from a standard lipid profile. RESULTS: During up to 15 years of follow-up, 236 individuals were diagnosed with peripheral artery disease, 234 with myocardial infarction, 226 with ischaemic stroke and 498 with any ASCVD. Multivariable adjusted HR (95% CI) per doubling of remnant cholesterol was 1.6 (1.1, 2.3; p=0.01) for peripheral artery disease, 1.8 (1.2, 2.5; p=0.002) for myocardial infarction, 1.5 (1.0, 2.1; p=0.04) for ischaemic stroke, and 1.6 (1.2, 2.0; p=0.0003) for any ASCVD. Excess risk conferred by diabetes was 2.5-fold for peripheral artery disease, 1.6-fold for myocardial infarction, 1.4-fold for ischaemic stroke and 1.6-fold for any ASCVD. Excess risk explained by elevated remnant cholesterol and low-grade inflammation was 14% and 8% for peripheral artery disease, 26% and 16% for myocardial infarction, 34% and 34% for ischaemic stroke, and 24% and 18% for any ASCVD, respectively. LDL-cholesterol did not explain excess risk, as it was not higher in individuals with diabetes. We also explored the fraction of excess risk conferred by diabetes which can be explained by elevated remnant cholesterol. CONCLUSIONS/INTERPRETATION: Elevated remnant cholesterol was associated with increased risk of ASCVD in individuals with diabetes. Remnant cholesterol and low-grade inflammation explained substantial excess risk of ASCVD conferred by diabetes. Whether remnant cholesterol should be used as a treatment target remains to be determined in randomised controlled trials.


Assuntos
Aterosclerose , Isquemia Encefálica , Doenças Cardiovasculares , Diabetes Mellitus , Hipercolesterolemia , AVC Isquêmico , Infarto do Miocárdio , Doença Arterial Periférica , Acidente Vascular Cerebral , Humanos , Doenças Cardiovasculares/etiologia , Estudos Prospectivos , Isquemia Encefálica/epidemiologia , Acidente Vascular Cerebral/epidemiologia , Aterosclerose/diagnóstico , Colesterol , Diabetes Mellitus/epidemiologia , Inflamação , Infarto do Miocárdio/epidemiologia , Doença Arterial Periférica/epidemiologia , AVC Isquêmico/complicações , Fatores de Risco
11.
Curr Atheroscler Rep ; 25(11): 795-803, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37768410

RESUMO

PURPOSE OF REVIEW: Recent large clinical trials have failed to show that triglyceride-rich lipoprotein-lowering therapies decrease the risk of atherosclerotic cardiovascular disease (ASCVD). In this review, we reconcile these findings with evidence showing that elevated levels of triglyceride-rich lipoproteins and the cholesterol they contain, remnant cholesterol, cause ASCVD alongside low-density lipoprotein (LDL) cholesterol. RECENT FINDINGS: Results from observational epidemiology, genetic epidemiology, and randomized controlled trials indicate that lowering of remnant cholesterol and LDL cholesterol decrease ASCVD risk by a similar magnitude per 1 mmol/L (39 mg/dL) lower non-high-density lipoprotein cholesterol (remnant cholesterol+LDL cholesterol). Indeed, recent guidelines for ASCVD prevention recommend the use of non-high-density lipoprotein cholesterol instead of LDL cholesterol. Current consensus is moving towards recognizing remnant cholesterol and LDL cholesterols as equals per 1 mmol/L (39 mg/dL) higher levels in the risk assessment of ASCVD; hence, triglyceride-rich lipoprotein-lowering therapies should also lower levels of non-HDL cholesterol to reduce ASCVD risk.


Assuntos
Aterosclerose , Lipoproteínas , Humanos , LDL-Colesterol , Triglicerídeos , Colesterol , Aterosclerose/tratamento farmacológico
12.
BJUI Compass ; 4(5): 513-522, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37636207

RESUMO

Background: Prostate-specific membrane antigen (PSMA)-positron emission tomography/contrast-enhanced computed tomography (PET/CT) is a sensitive imaging modality for prostate cancer (PCa). Due to lack of knowledge of the patient benefit, PSMA-PET/CT is not yet recommended in the European guidelines for staging and treatment planning of patients with newly diagnosed PCa. We will investigate the potential difference in progression-free survival (PFS) and quality of life (QoL) of using PSMA-PET/CT versus sodium fluoride (NaF)-PET/CT for staging and treatment planning in patients with newly diagnosed PCa. Study Design: This is a prospective randomised controlled multicentre trial carried out at three centres in the Region of Southern Denmark. Endpoints: The primary endpoint is PFS. Secondary endpoints are residual disease, stage migration, impact on treatment strategies, stage distribution, QoL and diagnostic accuracy measures. Patients and Methods: Patients eligible for the study have newly diagnosed unfavourable intermediate- or high-risk PCa. A total of 448 patients will be randomised 1:1 into two groups: (A) a control group staged with Na[18F]F-PET/CT and (B) an intervention group staged with [18F]PSMA-1007-PET/CT. A subgroup in the intervention group will have a supplementary blinded Na[18F]F-PET/CT performed for the purpose of performing accuracy analyses. QoL will be assessed at baseline and with regular intervals (3-12 months) during the study period. Treatment decisions are achieved at multidisciplinary team conferences based on the results of the respective scans and according to current Danish guidelines. Trial Registration: The Regional Committees on Health Research Ethics for Southern Denmark (S-20190161) and the Danish Medicines Agency (EudraCT Number 2021-000123-12) approved the study, and it has been registered on clinicaltrials.gov (Record 2020110469).

13.
Phys Chem Chem Phys ; 25(35): 23417-23434, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37486006

RESUMO

We apply ultrashort X-ray laser pulses to track optically excited structural dynamics of [Ir2(dimen)4]2+ molecules in solution. In our exploratory study we determine angular correlations in the scattered X-rays, which comprise a complex fingerprint of the ultrafast dynamics. Model-assisted analysis of the experimental correlation data allows us to elucidate various aspects of the photoinduced changes in the excited molecular ensembles. We unambiguously identify that in our experiment the photoinduced transition dipole moments in [Ir2(dimen)4]2+ molecules are oriented perpendicular to the Ir-Ir bond. The analysis also shows that the ground state conformer of [Ir2(dimen)4]2+ with a larger Ir-Ir distance is mostly responsible for the formation of the excited state. We also reveal that the ensemble of solute molecules can be characterized with a substantial structural heterogeneity due to solvent influence. The proposed X-ray correlation approach offers an alternative path for studies of ultrafast structural dynamics of molecular ensembles in the liquid and gas phases.

15.
J Chem Inf Model ; 63(12): 3827-3838, 2023 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-37279107

RESUMO

After two decades of continued development of the Martini coarse-grained force field (CG FF), further refinment of the already rather accurate Martini lipid models has become a demanding task that could benefit from integrative data-driven methods. Automatic approaches are increasingly used in the development of accurate molecular models, but they typically make use of specifically designed interaction potentials that transfer poorly to molecular systems or conditions different than those used for model calibration. As a proof of concept, here, we employ SwarmCG, an automatic multiobjective optimization approach facilitating the development of lipid force fields, to refine specifically the bonded interaction parameters in building blocks of lipid models within the framework of the general Martini CG FF. As targets of the optimization procedure, we employ both experimental observables (top-down references: area per lipid and bilayer thickness) and all-atom molecular dynamics simulations (bottom-up reference), which respectively inform on the supra-molecular structure of the lipid bilayer systems and on their submolecular dynamics. In our training sets, we simulate at different temperatures in the liquid and gel phases up to 11 homogeneous lamellar bilayers composed of phosphatidylcholine lipids spanning various tail lengths and degrees of (un)saturation. We explore different CG representations of the molecules and evaluate improvements a posteriori using additional simulation temperatures and a portion of the phase diagram of a DOPC/DPPC mixture. Successfully optimizing up to ∼80 model parameters within still limited computational budgets, we show that this protocol allows the obtainment of improved transferable Martini lipid models. In particular, the results of this study demonstrate how a fine-tuning of the representation and parameters of the models may improve their accuracy and how automatic approaches, such as SwarmCG, may be very useful to this end.


Assuntos
Bicamadas Lipídicas , Fosfatidilcolinas , Fosfatidilcolinas/química , Bicamadas Lipídicas/química , Temperatura , Simulação de Dinâmica Molecular
16.
Nat Commun ; 14(1): 3408, 2023 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-37296135

RESUMO

Control of magnetization and electric polarization is attractive in relation to tailoring materials for data storage and devices such as sensors or antennae. In magnetoelectric materials, these degrees of freedom are closely coupled, allowing polarization to be controlled by a magnetic field, and magnetization by an electric field, but the magnitude of the effect remains a challenge in the case of single-phase magnetoelectrics for applications. We demonstrate that the magnetoelectric properties of the mixed-anisotropy antiferromagnet LiNi1-xFexPO4 are profoundly affected by partial substitution of Ni2+ ions with Fe2+ on the transition metal site. This introduces random site-dependent single-ion anisotropy energies and causes a lowering of the magnetic symmetry of the system. In turn, magnetoelectric couplings that are symmetry-forbidden in the parent compounds, LiNiPO4 and LiFePO4, are unlocked and the dominant coupling is enhanced by almost two orders of magnitude. Our results demonstrate the potential of mixed-anisotropy magnets for tuning magnetoelectric properties.


Assuntos
Eletricidade , Campos Magnéticos , Anisotropia , Imãs
17.
Curr Opin Lipidol ; 34(3): 96-104, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36752631

RESUMO

PURPOSE OF REVIEW: Inflammation is gaining attention as a target for prevention of atherosclerotic cardiovascular disease (ASCVD). The purpose of this review is to compare the evidence for inflammation with the evidence for low-density lipoprotein (LDL) cholesterol in ASCVD. RECENT FINDINGS: Evidence from human genetic studies and randomized controlled trials implicate the inflammatory pathway from the inflammasome through interleukin (IL)-1 to IL-6 as a cause of ASCVD. Higher levels of IL-6 may lead to proportionally increased risk of ASCVD, and randomized controlled trials of IL-6 inhibitors are underway. The causal evidence for LDL cholesterol in ASCVD is overwhelming and recent important findings instead revolve around development of improved LDL cholesterol lowering therapy through RNA and DNA based therapeutics. Even though some lipid-lowering therapies lower IL-6, the IL-6 inflammatory pathway and LDL cholesterol are two separate causes of ASCVD. SUMMARY: IL-6 mediated inflammation most likely causes ASCVD, in parallel with LDL cholesterol. However, fewer individuals in the general population are exposed to high IL-6 than high LDL cholesterol. For inflammation, future research should focus on improving efficacy and safety of anti-inflammatory therapy, and for LDL cholesterol, future research should focus on wider and more effective implementation of LDL cholesterol lowering therapy.


Assuntos
Aterosclerose , Doenças Cardiovasculares , Inibidores de Hidroximetilglutaril-CoA Redutases , Hipercolesterolemia , Hiperlipidemias , Humanos , LDL-Colesterol , Doenças Cardiovasculares/epidemiologia , Interleucina-6 , Colesterol , Aterosclerose/epidemiologia , Hipercolesterolemia/complicações , Hiperlipidemias/complicações , Inflamação/complicações
18.
Chem Commun (Camb) ; 59(12): 1609-1612, 2023 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-36692932

RESUMO

Self-assembly of trans-{EuI2} nodes and ditopic ligands leads to isoreticular 2D frameworks featuring a rare, non-kagome Archimedean tessellation. The topology and intra-layer Eu(II)-Eu(II) antiferromagnetic interactions provide the prerequisites for geometrical spin frustration, which, due to the spin state degeneracy, is key for novel phenomena such as enhanced magnetic refrigeration.

19.
Eur Heart J ; 44(16): 1432-1445, 2023 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-36631967

RESUMO

AIMS: Cholesterol carried in triglyceride-rich lipoproteins, also called remnant cholesterol, is being increasingly acknowledged as an important causal risk factor for atherosclerosis. Elevated remnant cholesterol, marked by elevated plasma triglycerides, is associated causally with an increased risk of atherosclerotic cardiovascular disease. The association with cause-specific mortality is, however, unclear. The aim of this study was to test the hypothesis that elevated remnant cholesterol and plasma triglycerides are associated with increased mortality from cardiovascular disease, cancer, and other causes. METHODS AND RESULTS: Using a contemporary population-based cohort, 87 192 individuals from the Copenhagen General Population Study aged 20-69 years at baseline in 2003-2015 were included. During up to 13 years of follow-up, 687 individuals died from cardiovascular disease, 1594 from cancer, and 856 from other causes, according to the National Danish Causes of Death Registry. In individuals with remnant cholesterol ≥1.0 mmol/L (≥39 mg/dL; 22% of the population) compared with those with levels <0.5 mmol/L (<19 mg/dL), multivariable-adjusted mortality hazard ratios were 2.2 (95% confidence interval 1.3-3.5) for cardiovascular disease, 1.0 (0.7-1.3) for cancer, and 2.1 (1.4-3.3) for other causes. Exploratory analysis of the cause of death subcategories showed corresponding hazard ratios of 4.4 (1.6-11) for ischemic heart disease, 8.4 (2.0-34) for infectious diseases, and 9.1 (1.9-43) for endocrinological diseases. Results for plasma triglycerides >2 vs. <1 mmol/L (>177 vs. <89 mg/dL) were similar. CONCLUSION: Remnant cholesterol of ≥1 mmol/L (39 mg/dL), present in 22% of the population, and plasma triglycerides of ≥2 mmol/L (177 mg/dL), present in 28% of the population, were associated with two-fold mortality from cardiovascular and other causes, but not from cancer. This novel finding should be confirmed in other cohorts.


Assuntos
Aterosclerose , Doenças Cardiovasculares , Isquemia Miocárdica , Humanos , Triglicerídeos , Colesterol , Isquemia Miocárdica/epidemiologia , Fatores de Risco , Aterosclerose/complicações
20.
Phys Chem Chem Phys ; 25(4): 3309-3322, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36630169

RESUMO

The magnetic properties of the nickelalumite-type layered double hydroxides (LDH), MAl4(OH)12(SO4)·3H2O (MAl4-LDH) with M = Co2+ (S = 3/2), Ni2+ (S = 1), or Cu2+ (S = 1/2) were determined by a combined experimental and computational approach. They represent three new inorganic, low-dimensional magnetic systems with a defect-free, structurally ordered magnetic lattice. They exhibit no sign of magnetic ordering down to 2 K in contrast to conventional hydrotalcite LDH. Detailed insight into the complex interplay between the choice of magnetic ion (M2+) and magnetic properties was obtained by a combination of magnetic susceptibility, heat capacity, neutron scattering, solid-state NMR spectroscopy, and first-principles calculations. The NiAl4- and especially CoAl4-LDH have pronounced zero-field splitting (ZFS, easy-axis and easy-plane, respectively) and weak ferromagnetic nearest-neighbour interactions. Thus, they are rare examples of predominantly zero-dimensional spin systems in dense, inorganic matrices. In contrast, CuAl4-LDH (S = 1/2) consists of weakly ferromagnetic S = 1/2 spin chains. For all three MAl4-LDH, good agreement is found between the experimental magnetic parameters (J, D, g) and first-principles quantum chemical calculations, which also predict that the interchain couplings are extremely weak (< 0.1 cm-1). Thus, our approach will be valuable for evaluation and prediction of magnetic properties in other inorganic materials.

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