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1.
Science ; 385(6704): 86-91, 2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38963852

RESUMO

Semiconductor moiré superlattices provide a versatile platform to engineer quantum solids composed of artificial atoms on moiré sites. Previous studies have mostly focused on the simplest correlated quantum solid-the Fermi-Hubbard model-in which intra-atom interactions are simplified to a single onsite repulsion energy U. Here we report the experimental observation of Wigner molecular crystals emerging from multielectron artificial atoms in twisted bilayer tungsten disulfide moiré superlattices. Using scanning tunneling microscopy, we demonstrate that Wigner molecules appear in multielectron artificial atoms when Coulomb interactions dominate. The array of Wigner molecules observed in a moiré superlattice comprises a crystalline phase of electrons: the Wigner molecular crystal, which is shown to be highly tunable through mechanical strain, moiré period, and carrier charge type.

2.
Neurobiol Dis ; 198: 106553, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38839022

RESUMO

α-Synuclein (α-syn) is a small protein that is involved in cell vesicle trafficking in neuronal synapses. A progressive aggregation of this protein is the expected molecular cause of Parkinson's disease, a disease that affects millions of people around the world. A growing body of evidence indicates that phospholipids can strongly accelerate α-syn aggregation and alter the toxicity of α-syn oligomers and fibrils formed in the presence of lipid vesicles. This effect is attributed to the presence of high copies of lysines in the N-terminus of the protein. In this study, we performed site-directed mutagenesis and replaced one out of two lysines at each of the five sites located in the α-syn N-terminus. Using several biophysical and cellular approaches, we investigated the extent to which six negatively charged fatty acids (FAs) could alter the aggregation properties of K10A, K23A, K32A, K43A, and K58A α-syn. We found that FAs uniquely modified the aggregation properties of K43A, K58A, and WT α-syn, as well as changed morphology of amyloid fibrils formed by these mutants. At the same time, FAs failed to cause substantial changes in the aggregation rates of K10A, K23A, and K32A α-syn, as well as alter the morphology and toxicity of the corresponding amyloid fibrils. Based on these results, we can conclude that K10, K23, and K32 amino acid residues play a critical role in protein-lipid interactions since their replacement on non-polar alanines strongly suppressed α-syn-lipid interactions.


Assuntos
Mutagênese Sítio-Dirigida , alfa-Sinucleína , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Humanos , Amiloide/metabolismo , Amiloide/genética , Ácidos Graxos/metabolismo
3.
Theranostics ; 14(8): 3267-3281, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38855181

RESUMO

Background: Myocardial infarction (MI) as a consequence of atherosclerosis-associated acute thrombosis is a leading cause of death and disability globally. Antiplatelet and anticoagulant drugs are standard therapies in preventing and treating MI. However, all clinically used drugs are associated with bleeding complications, which ultimately limits their use in patients with a high risk of bleeding. We have developed a new recombinant drug, targ-HSA-TAP, that combines targeting and specific inhibition of activated platelets as well as anticoagulation. This drug is designed and tested for a prolonged circulating half-life, enabling unique thromboprophylaxis without bleeding complications. Methods: Targ-HSA-TAP combines a single-chain antibody (scFv) that targets activated glycoprotein IIb/IIIa on activated platelets, human serum albumin (HSA) for prolonged circulation, and tick anticoagulant peptide (TAP) for coagulation FX inhibition. A non-binding scFv is employed as a non-targeting control (non-targ-HSA-TAP). Its efficacy was investigated in vivo using murine models of acute thrombosis and cardiac ischemia-reperfusion (I/R) injury. Results: Our experiments confirmed the targeting specificity of targ-HSA-TAP to activated platelets and demonstrated effective prevention of platelet aggregation and thrombus formation, as well as FXa inhibition in vitro. Thromboprophylactic administration of targ-HSA-TAP subcutaneously in mice prevented occlusion of the carotid artery after ferric chloride injury as compared to non-targ-HSA-TAP and PBS-control treated mice. By comparing the therapeutic outcomes between targ-TAP and targ-HSA-TAP, we demonstrate the significant improvements brought by the HSA fusion in extending the drug's half-life and enhancing its therapeutic window for up to 16 h post-administration. Importantly, tail bleeding time was not prolonged with targ-HSA-TAP in contrast to the clinically used anticoagulant enoxaparin. Furthermore, in a murine model of cardiac I/R injury, mice administered targ-HSA-TAP 10 h before injury demonstrated preserved cardiac function, with significantly higher ejection fraction and fractional shortening, as compared to the non-targ-HSA-TAP and PBS control groups. Advanced strain analysis revealed reduced myocardial deformation and histology confirmed a reduced infarct size in targ-HSA-TAP treated mice compared to control groups. Conclusion: The inclusion of HSA represents a significant advancement in the design of targeted therapeutic agents for thromboprophylaxis. Our activated platelet-targeted targ-HSA-TAP is a highly effective antithrombotic drug with both anticoagulant and antiplatelet effects while retaining normal hemostasis. The long half-life of targ-HSA-TAP provides the unique opportunity to use this antithrombotic drug for more effective, long-lasting and safer anti-thrombotic prophylaxis. In cases where MI occurs, this prophylactic strategy reduces thrombus burden and effectively reduces cardiac I/R injury.


Assuntos
Plaquetas , Hemorragia , Albumina Sérica Humana , Trombose , Animais , Camundongos , Trombose/prevenção & controle , Trombose/tratamento farmacológico , Humanos , Hemorragia/prevenção & controle , Plaquetas/efeitos dos fármacos , Plaquetas/metabolismo , Modelos Animais de Doenças , Masculino , Anticoagulantes/farmacologia , Anticoagulantes/uso terapêutico , Anticorpos de Cadeia Única/farmacologia , Anticorpos de Cadeia Única/uso terapêutico , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Infarto do Miocárdio/tratamento farmacológico , Camundongos Endogâmicos C57BL , Proteínas Recombinantes de Fusão/farmacologia , Proteínas Recombinantes de Fusão/uso terapêutico
4.
Protein Sci ; 33(7): e5078, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38895991

RESUMO

Alzheimer's disease is the fastest-growing neurodegenerative disease that affects over six million Americans. The abnormal aggregation of amyloid ß peptide and Tau protein is the expected molecular cause of the loss of neurons in brains of AD patients. A growing body of evidence indicates that lipids can alter the aggregation rate of amyloid ß peptide and modify the toxicity of amyloid ß aggregates. However, the role of lipids in Tau aggregation remains unclear. In this study, we utilized a set of biophysical methods to determine the extent to which phospatidylserine (PS) altered the aggregation properties of Tau isoforms with one (1N4R) and two (2N4R) N terminal inserts that enhance the binding of Tau to tubulin. We found that the length and saturation of fatty acids (FAs) in PS altered the aggregation rate of 2N4R isoform, while no changes in the aggregation rate of 1N4R were observed. These results indicate that N terminal inserts play an important role in protein-lipid interactions. We also found that PS could change the toxicity of 1N4R and 2N4R Tau fibrils, as well as alter molecular mechanisms by which these aggregates exert cytotoxicity to neurons. Finally, we found that although Tau fibrils formed in the presence and absence of PS endocytosed by cells, only fibril species that were formed in the presence of PS exert strong impairment of the cell mitochondria.


Assuntos
Fosfatidilserinas , Tubulina (Proteína) , Proteínas tau , Proteínas tau/metabolismo , Proteínas tau/química , Proteínas tau/toxicidade , Humanos , Fosfatidilserinas/metabolismo , Fosfatidilserinas/química , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/química , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Ligação Proteica , Neurônios/metabolismo , Neurônios/efeitos dos fármacos , Agregados Proteicos , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/química
5.
Dalton Trans ; 53(23): 9887-9895, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38807511

RESUMO

We report the extension of the common ß-diketimine proligand class, RArnacnacH (HC(RCNAr)2H), where R is an alkyl group such as Et or iPr, plus Ph, and Ar is a sterically demanding aryl substituent such as Dip = 2,6-diispropylphenyl, Dep = 2,6-diethylphenyl, Mes = 2,4,6-trimethylphenyl or mesityl, Xyl = 2,6-dimethylphenyl, via one-pot condensation procedures. When a condensation reaction is carried out using the chemical dehydrating agent PPSE (polyphosphoric acid trimethylsilylester), ß-diketiminate phosphorus(V) products such as (iPrMesnacnac)PO2 can also be obtained, which can be converted to the respective proligand iPrMesnacnacH via alkaline hydrolysis. The RArnacnacH proligands can be converted to their alkali metal complexes with common methods and we have found that deprotonation of iPrDipnacnacH is significantly more sluggish than that of related ß-diketimines with smaller backbone alkyl groups. The basicity of the RArnacnac- anions can play a role in the success of their salt metathesis chemistry and we have prepared and structurally characterised the EtDipnacnac-derived silicon(II) compounds (EtDipnacnac)SiBr and (EtDipnacnac')Si, where EtDipnacnac' is the deprotonated variant MeCHC(NDip)CHC(NDip)Et.

6.
IUCrdata ; 9(Pt 4): x240345, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38721002

RESUMO

In the title compound, {(C6H8N)[Zn2(HPO3)2(H2PO3)]}n, the constituent ZnO4, HPO3 and H2PO3 polyhedra of the inorganic component are linked into (010) sheets by Zn-O-P bonds (mean angle = 134.4°) and the layers are reinforced by O-H⋯O hydrogen bonds. The protonated templates are anchored to the inorganic sheets via bifurcated N-H⋯(O,O) hydrogen bonds.

7.
Sci Rep ; 14(1): 10172, 2024 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-38702411

RESUMO

The intricate hormonal and physiological changes of the menstrual cycle can influence health on a daily basis. Although prior studies have helped improve our understanding of the menstrual cycle, they often lack diversity in the populations included, sample size, and the span of reproductive and life stages. This paper aims to describe the dynamic differences in menstrual cycle characteristics and associated symptoms by age in a large global cohort of period-tracking application users. This work aims to contribute to our knowledge and understanding of female physiology at varying stages of reproductive aging. This cohort study included self-reported menstrual cycle and symptom information in a sample of Flo application users aged 18-55. Cycle and period length and their variability, and frequency of menstrual cycle symptom logs are described by the age of the user. Based on data logged by over 19 million global users of the Flo app, the length of the menstrual cycle and period show clear age-associated patterns. With higher age, cycles tend to get shorter (Cycle length: D ¯ = 1.85 days, Cohen's D = 0.59) and more variable (Cycle length SD: D ¯ = 0.42 days, Cohen's D = 0.09), until close to the chronological age (40-44) suggesting menopausal transition, when both cycles and periods become longer (Cycle length: D ¯ = 0.86 days, t = 48.85, Cohen's D = 0.26; Period length: D ¯ = 0.08, t = 15.6, Cohen's D = 0.07) and more variable (Cycle length SD: D ¯ = 2.80 days, t = 111.43, d = 0.51; Period length SD: D ¯ = 0.23 days, t = 67.81, Cohen's D = 0.31). The proportion of individuals with irregular cycles was highest in participants aged 51-55 (44.7%), and lowest in the 36-40 age group (28.3%). The spectrum of common menstrual cycle-related symptoms also varies with age. The frequency of logging of cramps and acne is lower in older participants, while logs of headache, backache, stress, and insomnia are higher in older users. Other symptoms show different patterns, such as breast tenderness and fatigue peaking between the ages of 20-40, or mood swings being most frequently logged in the youngest and oldest users. The menstrual cycle and related symptoms are not static throughout the lifespan. Understanding these age-related differences in cycle characteristics and symptoms is essential in understanding how best to care for and improve the daily experience for menstruators across the reproductive life span.


Assuntos
Ciclo Menstrual , Humanos , Feminino , Ciclo Menstrual/fisiologia , Adulto , Pessoa de Meia-Idade , Adolescente , Adulto Jovem , Estudos de Coortes , Reprodução/fisiologia , Autorrelato , Fatores Etários , Envelhecimento/fisiologia
8.
IUCrdata ; 9(Pt 3): x240235, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38586527

RESUMO

The title compound, C16H12FN3OS, a fluorinated di-thio-carbazate imine derivative, was synthesized by the one-pot, multi-component condensation reaction of hydrazine hydrate, carbon di-sulfide, 4-fluoro-benzyl chloride and isatin. The compound demonstrates near-planarity across much of the mol-ecule in the solid state and a Z configuration for the azomethine C=N bond. The Z form is further stabilized by the presence of an intra-molecular N-H⋯O hydrogen bond. In the extended structure, mol-ecules are linked into dimers by N-H⋯O hydrogen bonds and further connected into chains along either [20] or [100] by weak C-H⋯S and C-H⋯F hydrogen bonds, which further link into corrugated sheets and in combination form the overall three-dimensional network.

9.
J Phys Chem Lett ; 15(17): 4761-4766, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38661515

RESUMO

Heart tissue can experience a progressive accumulation of transthyretin (TTR), a small four subunit protein that transports holoretinol binding protein and thyroxine. This severe pathology is known as transthyretin amyloid cardiomyopathy. Numerous experimental studies indicated that the aggregation rate and toxicity of TTR fibrils could be altered by the presence of lipids; however, the role of plasmalogens in this process remains unknown. In this study, we investigate the effect of choline plasmalogens (CPs) with different lengths and saturations of fatty acids (FAs) on TTR aggregation. We found that CPs with saturated and unsaturated FAs strongly suppressed TTR aggregation. We also found that CPs with saturated FAs did not change the morphology of TTR fibrils; however, much thicker fibrillar species were formed in the presence of CPs with unsaturated FAs. Finally, we found that CPs with C16:0, C18:0, and C18:1 FAs substantially lowered the cytotoxicity of TTR fibrils that were formed in their presence.


Assuntos
Plasmalogênios , Pré-Albumina , Pré-Albumina/química , Pré-Albumina/metabolismo , Plasmalogênios/metabolismo , Plasmalogênios/química , Humanos , Amiloide/química , Amiloide/metabolismo , Agregados Proteicos/efeitos dos fármacos , Ácidos Graxos/química , Ácidos Graxos/metabolismo
10.
bioRxiv ; 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38559127

RESUMO

Addiction vulnerability is associated with the tendency to attribute incentive salience to reward predictive cues; both addiction and the attribution of incentive salience are influenced by environmental and genetic factors. To characterize the genetic contributions to incentive salience attribution, we performed a genome-wide association study (GWAS) in a cohort of 1,645 genetically diverse heterogeneous stock (HS) rats. We tested HS rats in a Pavlovian conditioned approach task, in which we characterized the individual responses to food-associated stimuli ("cues"). Rats exhibited either cue-directed "sign-tracking" behavior or food-cup directed "goal-tracking" behavior. We then used the conditioned reinforcement procedure to determine whether rats would perform a novel operant response for unrewarded presentations of the cue. We found that these measures were moderately heritable (SNP heritability, h2 = .189-.215). GWAS identified 14 quantitative trait loci (QTLs) for 11 of the 12 traits we examined. Interval sizes of these QTLs varied widely. 7 traits shared a QTL on chromosome 1 that contained a few genes (e.g. Tenm4, Mir708) that have been associated with substance use disorders and other mental health traits in humans. Other candidate genes (e.g. Wnt11, Pak1) in this region had coding variants and expression-QTLs in mesocorticolimbic regions of the brain. We also conducted a Phenome-Wide Association Study (PheWAS) on other behavioral measures in HS rats and found that regions containing QTLs on chromosome 1 were also associated with nicotine self-administration in a separate cohort of HS rats. These results provide a starting point for the molecular genetic dissection of incentive salience and provide further support for a relationship between attribution of incentive salience and drug abuse-related traits.

11.
Science ; 384(6693): 343-347, 2024 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-38669569

RESUMO

Semiconductor moiré superlattices have been shown to host a wide array of interaction-driven ground states. However, twisted homobilayers have been difficult to study in the limit of large moiré wavelengths, where interactions are most dominant. In this study, we conducted local electronic compressibility measurements of twisted bilayer WSe2 (tWSe2) at small twist angles. We demonstrated multiple topological bands that host a series of Chern insulators at zero magnetic field near a "magic angle" around 1.23°. Using a locally applied electric field, we induced a topological quantum-phase transition at one hole per moiré unit cell. Our work establishes the topological phase diagram of a generalized Kane-Mele-Hubbard model in tWSe2, demonstrating a tunable platform for strongly correlated topological phases.

12.
Int J Biol Macromol ; 264(Pt 1): 130632, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38447831

RESUMO

Plasmalogens comprise a large fraction of the total phospholipids in plasma membranes. These molecules modulate membrane fluidity, produce inflammatory mediators mitigating effects of metabolic stresses. A growing body of evidence suggests that an onset of Parkinson's disease (PD), a severe neurodegenerative pathology, can be triggered by metabolic changes in plasma membranes. However, the role of plasmalogens in the aggregation of α-synuclein (α-syn), an expected molecular cause of PD, remains unclear. In this study we examine the effect of choline plasmalogens (CPs), unique phospholipids that have a vinyl ether linkage at the sn-1 position of glycerol, on the aggregation rate of α-syn. We found that the length and saturation of fatty acids (FAs) in CPs change rates of protein aggregation. We also found drastic changes in the morphology of α-syn fibrils formed in the presence of different CPs compared to α-syn fibrils grown in the lipid-free environment. At the same time, we did not observe substantial changes in the secondary structure and toxicity of α-syn fibrils formed in the presence of different CPs. These results indicate that the length and saturation of FAs in CPs present in the plasma membrane can alter α-syn stability and modulate its aggregation properties, which, in turn can accelerate or delay the onset of PD.


Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , alfa-Sinucleína/química , Plasmalogênios , Amiloide/química , Doença de Parkinson/metabolismo
13.
Sci Rep ; 14(1): 6469, 2024 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-38499595

RESUMO

The discovery of clandestine burials poses unique challenges for forensic specialists, requiring diverse expertise to analyze remains in various states. Bones, teeth, and hair often endure the test of time, with hair particularly exposed to the external environment. While existing studies focus on the degradation of virgin hair influenced by soil pH and decomposition fluids, the interaction between artificial dyes on hair and soil remains underexplored. This paper introduces a novel approach to forensic hair analysis that is based on high-throughput, nondestructive, and non-invasive surface-enhanced Raman spectroscopy (SERS) and machine learning. Using this approach, we investigated the reliability of the detection and identification of artificial dyes on hair buried in three distinct soil types for up to eight weeks. Our results demonstrated that SERS enabled the correct prediction of 97.9% of spectra for five out of the eight dyes used within the 8 weeks of exposure. We also investigated the extent to which SERS and machine learning can be used to predict the number of weeks since burial, as this information may provide valuable insights into post-mortem intervals. We found that SERS enabled highly accurate exposure intervals to soils for specific dyes. The study underscores the high achievability of SERS in extrapolating colorant information from dyed hairs buried in diverse soils, with the suggestion that further model refinement could enhance its reliability in forensic applications.


Assuntos
Solo , Análise Espectral Raman , Análise Espectral Raman/métodos , Corantes , Reprodutibilidade dos Testes , Cabelo
14.
Molecules ; 29(4)2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38398597

RESUMO

Phospholane-phosphites are known to show highly unusual selectivity towards branched aldehydes in the hydroformylation of terminal alkenes. This paper describes the synthesis of hitherto unknown unsaturated phospholene borane precursors and their conversion to the corresponding phospholene-phosphites. The relative stereochemistry of one of these ligands and its Pd complex was assigned with the aid of X-ray crystal structure determinations. These ligands were able to approach the level of selectivity observed for phospholane-phosphites in the rhodium-catalysed hydroformylation of propene. High-pressure infra-red (HPIR) spectroscopic monitoring of the catalyst formation revealed that whilst the catalysts showed good thermal stability with respect to fragmentation, the C=C bond in the phospholene moiety was slowly hydrogenated in the presence of rhodium and syngas. The ability of this spectroscopic tool to detect even subtle changes in structure, remotely from the carbonyl ligands, underlines the usefulness of HPIR spectroscopy in hydroformylation catalyst development.

15.
Chemistry ; 30(21): e202303993, 2024 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-38315627

RESUMO

We report an approach to the diastereoselective synthesis of 1,2-disubstituted heterocyclic aziridines. A Brønsted acid-catalyzed conjugate addition of anilines to trisubstituted heterocyclic chloroalkenes provides an intermediate 1,2-chloroamine. Diastereocontrol was found to vary significantly with solvent selection, with computational modelling confirming selective, spontaneous fragmentation in the presence of trace acids, proceeding through a pseudo-cyclic, protonated intermediate and transition state. These chloroamines can then be converted to the aziridine by treatment with LiHMDS with high stereochemical fidelity. This solvent-induced stereochemical enrichment thereby enables an efficient route to rare cis-aziridines with high dr. The scope, limitations, and mechanistic origins of selectivity are also presented.

16.
J Gen Intern Med ; 39(7): 1180-1187, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38319498

RESUMO

BACKGROUND: Medicare's voluntary bundled payment programs have demonstrated generally favorable results. However, it remains unknown whether uneven hospital participation in these programs in communities with greater shares of minorities and patients of low socioeconomic status results in disparate access to practice redesign innovations. OBJECTIVE: Examine whether communities with higher proportions of marginalized individuals were less likely to be served by a hospital participating in Bundled Payments for Care Improvement Advanced (BPCI-Advanced). DESIGN: Cross-sectional study using ordinary least squares regression controlling for patient and community factors. PARTICIPANTS: Medicare fee-for-service patients enrolled from 2015-2017 (pre-BPCI-Advanced) and residing in 2,058 local communities nationwide defined by Hospital Service Areas (HSAs). Each community's share of marginalized patients was calculated separately for each of the share of beneficiaries of Black race, Hispanic ethnicity, or dual eligibility for Medicare and Medicaid. MAIN MEASURES: Dichotomous variable indicating whether a given community had at least one hospital that ever participated in BPCI-Advanced from 2018-2022. KEY RESULTS: Communities with higher shares of dual-eligible individuals were less likely to be served by a hospital participating in BPCI-Advanced than communities with the lowest quartile of dual-eligible individuals (Q4: -15.1 percentage points [pp] lower than Q1, 95% CI: -21.0 to -9.1, p < 0.001). There was no consistent significant relationship between community proportion of Black beneficiaries and likelihood of having a hospital participating in BPCI-Advanced. Communities with higher shares of Hispanic beneficiaries were more likely to have a hospital participating in BPCI-Advanced than those in the lowest quartile (Q4: 19.2 pp higher than Q1, 95% CI: 13.4 to 24.9, p < 0.001). CONCLUSIONS: Communities with greater shares of dual-eligible beneficiaries, but not racial or ethnic minorities, were less likely to be served by a hospital participating in BPCI-Advanced Policymakers should consider approaches to incentivize more socioeconomically uniform participation in voluntary bundled payments.


Assuntos
Medicare , Humanos , Estados Unidos , Estudos Transversais , Medicare/economia , Masculino , Feminino , Idoso , Pacotes de Assistência ao Paciente/economia , Planos de Pagamento por Serviço Prestado/economia , Hospitais/estatística & dados numéricos , Idoso de 80 Anos ou mais
17.
ACS Catal ; 14(3): 1846-1854, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38327642

RESUMO

Benzoxaboraheterocycles (BOBs) are moieties of increasing interest in the pharmaceutical industry; however, the synthesis of these compounds is often difficult or impractical due to the sensitivity of the boron moiety, the requirement for metalation-borylation protocols, and lengthy syntheses. We report a straightforward, modular approach that enables access to complex examples of the BOB framework through a Rh-catalyzed [2 + 2 + 2] cycloaddition using MIDA-protected alkyne boronic acids. The key to the development of this methodology was overcoming the steric barrier to catalysis by leveraging chelation assistance. We show the utility of the method through synthesis of a broad range of BOB scaffolds, mechanistic information on the chelation effect, intramolecular alcohol-assisted BMIDA hydrolysis, and linear/cyclic BOB limits as well as comparative binding affinities of the product BOB frameworks for ribose-derived biomolecules.

18.
Mol Pharm ; 21(3): 1334-1341, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38373398

RESUMO

Parkinson's disease (PD) is a severe pathology that is caused by a progressive degeneration of dopaminergic neurons in substantia nigra pars compacta as well as other areas in the brain. These neurodegeneration processes are linked to the abrupt aggregation of α-synuclein (α-syn), a small protein that is abundant at presynaptic nerve termini, where it regulates cell vesicle trafficking. Due to the direct interactions of α-syn with cell membranes, a substantial amount of work was done over the past decade to understand the role of lipids in α-syn aggregation. However, the role of phosphatidic acid (PA), a negatively charged phospholipid with a small polar head, remains unclear. In this study, we examined the effect of PA large unilamellar vesicles (LUVs) on α-syn aggregation. We found that PA LUVs with 16:0, 18:0, and 18:1 FAs drastically reduced the toxicity of α-syn fibrils if were present in a 1:1 molar ratio with the protein. Our results also showed that the presence of these vehicles changed the rate of α-syn aggregation and altered the morphology and secondary structure of α-syn fibrils. These results indicate that PA LUVs can be used as a potential therapeutic strategy to reduce the toxicity of α-syn fibrils formed upon PD.


Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , alfa-Sinucleína/metabolismo , Lipossomas Unilamelares/metabolismo , Doença de Parkinson/metabolismo , Neurônios Dopaminérgicos/metabolismo
19.
Nature ; 626(8000): 759-764, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38383622

RESUMO

The fractional quantum anomalous Hall effect (FQAHE), the analogue of the fractional quantum Hall effect1 at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking2-6. The demonstration of FQAHE could lead to non-Abelian anyons that form the basis of topological quantum computation7-9. So far, FQAHE has been observed only in twisted MoTe2 at a moiré filling factor v > 1/2 (refs. 10-13). Graphene-based moiré superlattices are believed to host FQAHE with the potential advantage of superior material quality and higher electron mobility. Here we report the observation of integer and fractional QAH effects in a rhombohedral pentalayer graphene-hBN moiré superlattice. At zero magnetic field, we observed plateaus of quantized Hall resistance [Formula: see text] at v = 1, 2/3, 3/5, 4/7, 4/9, 3/7 and 2/5 of the moiré superlattice, respectively, accompanied by clear dips in the longitudinal resistance Rxx. Rxy equals [Formula: see text] at v = 1/2 and varies linearly with v, similar to the composite Fermi liquid in the half-filled lowest Landau level at high magnetic fields14-16. By tuning the gate-displacement field D and v, we observed phase transitions from composite Fermi liquid and FQAH states to other correlated electron states. Our system provides an ideal platform for exploring charge fractionalization and (non-Abelian) anyonic braiding at zero magnetic field7-9,17-19, especially considering a lateral junction between FQAHE and superconducting regions in the same device20-22.

20.
RSC Adv ; 14(3): 1833-1837, 2024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38192310

RESUMO

Palmer amaranth (Amaranthus palmeri) is a pervasive and troublesome weed species that poses significant challenges to agriculture in the United States. Identifying the sex of Palmer amaranth plants is crucial for developing tailored control measures due to the distinct characteristics and reproductive strategies exhibited by male and female plants. Traditional methods for sex determination are expensive and time-consuming, but recent advancements in spectroscopic techniques offer new possibilities. This study explores the potential of portable Raman spectroscopy for determining the sex of mature Palmer amaranth plants in-field. Raman analysis of the plant leaves reveals spectral differences associated with nitrate salts, lipids, carotenoids, and terpenoids, allowing for high accuracy and reliable identification of the plant's sex; male plants had higher concentrations of these compounds compared to females. It was also found that male plants had higher concentrations of these compounds compared to the females. Raman spectra were analyzed using a machine learning tool, partial least squares discriminant analysis (PLS-DA), to generate accuracies of no less than 83.7% when elucidating sex from acquired spectra. These findings provide insights into the sex-specific characteristics of Palmer amaranth and suggest that Raman analysis, combined with PLS-DA, can be a promising, non-destructive, and efficient method for sex determination in field settings. This approach has implications for developing sex-specific management strategies to monitor and control this invasive weed in real-world environments, benefiting farmers, agronomists, researchers, and master gardeners.

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