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Colección Odontología Uruguay
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1.
Cell ; 183(7): 1986-2002.e26, 2020 12 23.
Artículo en Inglés | MEDLINE | ID: mdl-33333022

RESUMEN

Serotonin plays a central role in cognition and is the target of most pharmaceuticals for psychiatric disorders. Existing drugs have limited efficacy; creation of improved versions will require better understanding of serotonergic circuitry, which has been hampered by our inability to monitor serotonin release and transport with high spatial and temporal resolution. We developed and applied a binding-pocket redesign strategy, guided by machine learning, to create a high-performance, soluble, fluorescent serotonin sensor (iSeroSnFR), enabling optical detection of millisecond-scale serotonin transients. We demonstrate that iSeroSnFR can be used to detect serotonin release in freely behaving mice during fear conditioning, social interaction, and sleep/wake transitions. We also developed a robust assay of serotonin transporter function and modulation by drugs. We expect that both machine-learning-guided binding-pocket redesign and iSeroSnFR will have broad utility for the development of other sensors and in vitro and in vivo serotonin detection, respectively.


Asunto(s)
Evolución Molecular Dirigida , Aprendizaje Automático , Serotonina/metabolismo , Algoritmos , Secuencia de Aminoácidos , Amígdala del Cerebelo/fisiología , Animales , Conducta Animal , Sitios de Unión , Encéfalo/metabolismo , Células HEK293 , Humanos , Cinética , Modelos Lineales , Ratones , Ratones Endogámicos C57BL , Fotones , Unión Proteica , Proteínas de Transporte de Serotonina en la Membrana Plasmática/metabolismo , Sueño/fisiología , Vigilia/fisiología
2.
Cell ; 166(4): 907-919, 2016 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-27499021

RESUMEN

Classically, G protein-coupled receptor (GPCR) stimulation promotes G protein signaling at the plasma membrane, followed by rapid ß-arrestin-mediated desensitization and receptor internalization into endosomes. However, it has been demonstrated that some GPCRs activate G proteins from within internalized cellular compartments, resulting in sustained signaling. We have used a variety of biochemical, biophysical, and cell-based methods to demonstrate the existence, functionality, and architecture of internalized receptor complexes composed of a single GPCR, ß-arrestin, and G protein. These super-complexes or "megaplexes" more readily form at receptors that interact strongly with ß-arrestins via a C-terminal tail containing clusters of serine/threonine phosphorylation sites. Single-particle electron microscopy analysis of negative-stained purified megaplexes reveals that a single receptor simultaneously binds through its core region with G protein and through its phosphorylated C-terminal tail with ß-arrestin. The formation of such megaplexes provides a potential physical basis for the newly appreciated sustained G protein signaling from internalized GPCRs.


Asunto(s)
Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal , beta-Arrestinas/metabolismo , Transferencia de Energía por Resonancia de Bioluminiscencia , AMP Cíclico/metabolismo , Endosomas/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gs/metabolismo , Células HEK293 , Humanos , Microscopía Confocal , Microscopía Electrónica , Complejos Multiproteicos , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/química , beta-Arrestinas/química
3.
Nature ; 613(7944): 468-473, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36653567

RESUMEN

Producing quantum states at random has become increasingly important in modern quantum science, with applications being both theoretical and practical. In particular, ensembles of such randomly distributed, but pure, quantum states underlie our understanding of complexity in quantum circuits1 and black holes2, and have been used for benchmarking quantum devices3,4 in tests of quantum advantage5,6. However, creating random ensembles has necessitated a high degree of spatio-temporal control7-12 placing such studies out of reach for a wide class of quantum systems. Here we solve this problem by predicting and experimentally observing the emergence of random state ensembles naturally under time-independent Hamiltonian dynamics, which we use to implement an efficient, widely applicable benchmarking protocol. The observed random ensembles emerge from projective measurements and are intimately linked to universal correlations built up between subsystems of a larger quantum system, offering new insights into quantum thermalization13. Predicated on this discovery, we develop a fidelity estimation scheme, which we demonstrate for a Rydberg quantum simulator with up to 25 atoms using fewer than 104 experimental samples. This method has broad applicability, as we demonstrate for Hamiltonian parameter estimation, target-state generation benchmarking, and comparison of analogue and digital quantum devices. Our work has implications for understanding randomness in quantum dynamics14 and enables applications of this concept in a much wider context4,5,9,10,15-20.

4.
Genes Dev ; 34(13-14): 863-864, 2020 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-32611612

RESUMEN

R loops arise from hybridization of RNA transcripts with template DNA during transcription. Unrepaired R loops lead to transcription-replication collisions, causing DNA damage and genomic instability. In this issue of Genes & Development, Pérez-Calero and colleagues (pp. 898-912) identify UAP56 as a cotranscriptional RNA-DNA helicase that unwinds R loops. They found that UAP56 helicase activity is required to remove R loops formed from different sources and prevent R-loop accumulation genome-wide at actively transcribed genes.


Asunto(s)
Genoma/genética , Estructuras R-Loop/genética , Transcripción Genética/genética , Cromatina/metabolismo , ARN Helicasas DEAD-box/genética , ARN Helicasas DEAD-box/metabolismo , Inestabilidad Genómica/genética , Humanos , Células K562
5.
PLoS Biol ; 21(9): e3002319, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37747915

RESUMEN

Spontaneous Ca2+ transients of neural cells is a hallmark of the developing nervous system. It is widely accepted that chemical signals, like neurotransmitters, contribute to spontaneous Ca2+ transients in the nervous system. Here, we reveal an additional mechanism of spontaneous Ca2+ transients that is mechanosensitive in the peripheral nervous system (PNS) using intravital imaging of growing dorsal root ganglia (DRG) in zebrafish embryos. GCaMP6s imaging shows that developing DRG satellite glia contain distinct spontaneous Ca2+ transients, classified into simultaneous, isolated, and microdomains. Longitudinal analysis over days in development demonstrates that as DRG satellite glia become more synchronized, isolated Ca2+ transients remain constant. Using a chemical screen, we identify that Ca2+ transients in DRG glia are dependent on mechanical properties, which we confirmed using an experimental application of mechanical force. We find that isolated spontaneous Ca2+ transients of the glia during development is altered by manipulation of mechanosensitive protein Piezo1, which is expressed in the developing ganglia. In contrast, simultaneous Ca2+ transients of DRG satellite glia is not Piezo1-mediated, thus demonstrating that distinct mechanisms mediate subtypes of spontaneous Ca2+ transients. Activating Piezo1 eventually impacts the cell abundance of DRG cells and behaviors that are driven by DRG neurons. Together, our results reveal mechanistically distinct subtypes of Ca2+ transients in satellite glia and introduce mechanobiology as a critical component of spontaneous Ca2+ transients in the developing PNS.


Asunto(s)
Calcio , Ganglios Espinales , Animales , Calcio/metabolismo , Ganglios Espinales/metabolismo , Pez Cebra/metabolismo , Neuroglía/metabolismo , Neuronas/metabolismo , Canales Iónicos/metabolismo , Proteínas de Pez Cebra/metabolismo
6.
Nature ; 578(7796): 545-549, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32103195

RESUMEN

Chirality is ubiquitous in nature, and populations of opposite chiralities are surprisingly asymmetric at fundamental levels1,2. Examples range from parity violation in the subatomic weak force to homochirality in biomolecules. The ability to achieve chirality-selective synthesis (chiral induction) is of great importance in stereochemistry, molecular biology and pharmacology2. In condensed matter physics, a crystalline electronic system is geometrically chiral when it lacks mirror planes, space-inversion centres or rotoinversion axes1. Typically, geometrical chirality is predefined by the chiral lattice structure of a material, which is fixed on formation of the crystal. By contrast, in materials with gyrotropic order3-6, electrons spontaneously organize themselves to exhibit macroscopic chirality in an originally achiral lattice. Although such order-which has been proposed as the quantum analogue of cholesteric liquid crystals-has attracted considerable interest3-15, no clear observation or manipulation of gyrotropic order has been achieved so far. Here we report the realization of optical chiral induction and the observation of a gyrotropically ordered phase in the transition-metal dichalcogenide semimetal 1T-TiSe2. We show that shining mid-infrared circularly polarized light on 1T-TiSe2 while cooling it below the critical temperature leads to the preferential formation of one chiral domain. The chirality of this state is confirmed by the measurement of an out-of-plane circular photogalvanic current, the direction of which depends on the optical induction. Although the role of domain walls requires further investigation with local probes, the methodology demonstrated here can be applied to realize and control chiral electronic phases in other quantum materials4,16.

7.
Proc Natl Acad Sci U S A ; 120(16): e2210418120, 2023 04 18.
Artículo en Inglés | MEDLINE | ID: mdl-37040401

RESUMEN

The hypoxia-inducible factor 1-α (HIF-1α) enables cells to adapt and respond to hypoxia (Hx), and the activity of this transcription factor is regulated by several oncogenic signals and cellular stressors. While the pathways controlling normoxic degradation of HIF-1α are well understood, the mechanisms supporting the sustained stabilization and activity of HIF-1α under Hx are less clear. We report that ABL kinase activity protects HIF-1α from proteasomal degradation during Hx. Using a fluorescence-activated cell sorting (FACS)-based CRISPR/Cas9 screen, we identified HIF-1α as a substrate of the cleavage and polyadenylation specificity factor-1 (CPSF1), an E3-ligase which targets HIF-1α for degradation in the presence of an ABL kinase inhibitor in Hx. We show that ABL kinases phosphorylate and interact with CUL4A, a cullin ring ligase adaptor, and compete with CPSF1 for CUL4A binding, leading to increased HIF-1α protein levels. Further, we identified the MYC proto-oncogene protein as a second CPSF1 substrate and show that active ABL kinase protects MYC from CPSF1-mediated degradation. These studies uncover a role for CPSF1 in cancer pathobiology as an E3-ligase antagonizing the expression of the oncogenic transcription factors, HIF-1α and MYC.


Asunto(s)
Regulación de la Expresión Génica , Factores de Transcripción , Humanos , Proteínas Cullin/metabolismo , Hipoxia , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Factores de Transcripción/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Genes abl , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Factor de Especificidad de Desdoblamiento y Poliadenilación/metabolismo
8.
Proc Natl Acad Sci U S A ; 120(28): e2303312120, 2023 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-37410867

RESUMEN

New properties and exotic quantum phenomena can form due to periodic nanotextures, including Moire patterns, ferroic domains, and topologically protected magnetization and polarization textures. Despite the availability of powerful tools to characterize the atomic crystal structure, the visualization of nanoscale strain-modulated structural motifs remains challenging. Here, we develop nondestructive real-space imaging of periodic lattice distortions in thin epitaxial films and report an emergent periodic nanotexture in a Mott insulator. Specifically, we combine iterative phase retrieval with unsupervised machine learning to invert the diffuse scattering pattern from conventional X-ray reciprocal-space maps into real-space images of crystalline displacements. Our imaging in PbTiO3/SrTiO3 superlattices exhibiting checkerboard strain modulation substantiates published phase-field model calculations. Furthermore, the imaging of biaxially strained Mott insulator Ca2RuO4 reveals a strain-induced nanotexture comprised of nanometer-thin metallic-structure wires separated by nanometer-thin Mott-insulating-structure walls, as confirmed by cryogenic scanning transmission electron microscopy (cryo-STEM). The nanotexture in Ca2RuO4 film is induced by the metal-to-insulator transition and has not been reported in bulk crystals. We expect the phasing of diffuse X-ray scattering from thin crystalline films in combination with cryo-STEM to open a powerful avenue for discovering, visualizing, and quantifying the periodic strain-modulated structures in quantum materials.


Asunto(s)
Películas Cinematográficas , Refracción Ocular , Aprendizaje Automático no Supervisado
9.
N Engl J Med ; 387(2): 132-147, 2022 07 14.
Artículo en Inglés | MEDLINE | ID: mdl-35660812

RESUMEN

BACKGROUND: In patients with newly diagnosed multiple myeloma, the effect of adding autologous stem-cell transplantation (ASCT) to triplet therapy (lenalidomide, bortezomib, and dexamethasone [RVD]), followed by lenalidomide maintenance therapy until disease progression, is unknown. METHODS: In this phase 3 trial, adults (18 to 65 years of age) with symptomatic myeloma received one cycle of RVD. We randomly assigned these patients, in a 1:1 ratio, to receive two additional RVD cycles plus stem-cell mobilization, followed by either five additional RVD cycles (the RVD-alone group) or high-dose melphalan plus ASCT followed by two additional RVD cycles (the transplantation group). Both groups received lenalidomide until disease progression, unacceptable side effects, or both. The primary end point was progression-free survival. RESULTS: Among 357 patients in the RVD-alone group and 365 in the transplantation group, at a median follow-up of 76.0 months, 328 events of disease progression or death occurred; the risk was 53% higher in the RVD-alone group than in the transplantation group (hazard ratio, 1.53; 95% confidence interval [CI], 1.23 to 1.91; P<0.001); median progression-free survival was 46.2 months and 67.5 months. The percentage of patients with a partial response or better was 95.0% in the RVD-alone group and 97.5% in the transplantation group (P = 0.55); 42.0% and 46.8%, respectively, had a complete response or better (P = 0.99). Treatment-related adverse events of grade 3 or higher occurred in 78.2% and 94.2%, respectively; 5-year survival was 79.2% and 80.7% (hazard ratio for death, 1.10; 95% CI, 0.73 to 1.65). CONCLUSIONS: Among adults with multiple myeloma, RVD plus ASCT was associated with longer progression-free survival than RVD alone. No overall survival benefit was observed. (Funded by the National Heart, Lung, and Blood Institute and others; DETERMINATION ClinicalTrials.gov number, NCT01208662.).


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica , Quimioterapia de Mantención , Mieloma Múltiple , Trasplante de Células Madre , Adulto , Antineoplásicos/efectos adversos , Antineoplásicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Bortezomib/administración & dosificación , Bortezomib/efectos adversos , Dexametasona/administración & dosificación , Dexametasona/efectos adversos , Progresión de la Enfermedad , Supervivencia sin Enfermedad , Humanos , Lenalidomida/administración & dosificación , Lenalidomida/efectos adversos , Quimioterapia de Mantención/métodos , Melfalán/administración & dosificación , Mieloma Múltiple/diagnóstico , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/cirugía , Trasplante Autólogo
10.
Nucleic Acids Res ; 51(20): 11298-11317, 2023 11 10.
Artículo en Inglés | MEDLINE | ID: mdl-37855684

RESUMEN

We conducted a thermodynamic analysis of RNA stability in Eco80 artificial cytoplasm, which mimics in vivo conditions, and compared it to transcriptome-wide probing of mRNA. Eco80 contains 80% of Escherichia coli metabolites, with biological concentrations of metal ions, including 2 mM free Mg2+ and 29 mM metabolite-chelated Mg2+. Fluorescence-detected binding isotherms (FDBI) were used to conduct a thermodynamic analysis of 24 RNA helices and found that these helices, which have an average stability of -12.3 kcal/mol, are less stable by ΔΔGo37 ∼1 kcal/mol. The FDBI data was used to determine a set of Watson-Crick free energy nearest neighbor parameters (NNPs), which revealed that Eco80 reduces the stability of three NNPs. This information was used to adjust the NN model using the RNAstructure package. The in vivo-like adjustments have minimal effects on the prediction of RNA secondary structures determined in vitro and in silico, but markedly improve prediction of fractional RNA base pairing in E. coli, as benchmarked with our in vivo DMS and EDC RNA chemical probing data. In summary, our thermodynamic and chemical probing analyses of RNA helices indicate that RNA secondary structures are less stable in cells than in artificially stable in vitro buffer conditions.


Asunto(s)
Escherichia coli , Estabilidad del ARN , Emparejamiento Base , Secuencia de Bases , Escherichia coli/química , Escherichia coli/genética , Magnesio , Conformación de Ácido Nucleico , ARN/genética , ARN/química , Termodinámica
11.
Proc Natl Acad Sci U S A ; 119(25): e2201237119, 2022 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-35696576

RESUMEN

RNA structure plays roles in myriad cellular events including transcription, translation, and RNA processing. Genome-wide analyses of RNA secondary structure in vivo by chemical probing have revealed critical structural features of mRNAs and long ncRNAs. Here, we examine the in vivo secondary structure of a small RNA class, tRNAs. Study of tRNA structure is challenging because tRNAs are heavily modified and strongly structured. We introduce "tRNA structure-seq," a new workflow that accurately determines in vivo secondary structures of tRNA. The workflow combines dimethyl sulfate (DMS) probing, ultra-processive RT, and mutational profiling (MaP), which provides mutations opposite DMS and natural modifications thereby allowing multiple modifications to be identified in a single read. We applied tRNA structure-seq to E. coli under control and stress conditions. A leading folding algorithm predicts E. coli tRNA structures with only ∼80% average accuracy from sequence alone. Strikingly, tRNA structure-seq, by providing experimental restraints, improves structure prediction under in vivo conditions to ∼95% accuracy, with more than 14 tRNAs predicted completely correctly. tRNA structure-seq also quantifies the relative levels of tRNAs and their natural modifications at single nucleotide resolution, as validated by LC-MS/MS. Our application of tRNA structure-seq yields insights into tRNA structure in living cells, revealing that it is not immutable but has dynamics, with partial unfolding of secondary and tertiary tRNA structure under heat stress that is correlated with a loss of tRNA abundance. This method is applicable to other small RNAs, including those with natural modifications and highly structured regions.


Asunto(s)
Escherichia coli , Respuesta al Choque Térmico , ARN de Transferencia , Cromatografía Liquida , Escherichia coli/genética , Estudio de Asociación del Genoma Completo , Respuesta al Choque Térmico/genética , Conformación de Ácido Nucleico , ARN de Transferencia/química , Análisis de Secuencia de ARN/métodos , Espectrometría de Masas en Tándem
12.
J Am Soc Nephrol ; 35(2): 135-148, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-38044490

RESUMEN

SIGNIFICANCE STATEMENT: In this study, we demonstrate that a common, low-cost compound known as octanedioic acid (DC 8 ) can protect mice from kidney damage typically caused by ischemia-reperfusion injury or the chemotherapy drug cisplatin. This compound seems to enhance peroxisomal activity, which is responsible for breaking down fats, without adversely affecting mitochondrial function. DC 8 is not only affordable and easy to administer but also effective. These encouraging findings suggest that DC 8 could potentially be used to assist patients who are at risk of experiencing this type of kidney damage. BACKGROUND: Proximal tubules are rich in peroxisomes, which are damaged during AKI. Previous studies demonstrated that increasing peroxisomal fatty acid oxidation (FAO) is renoprotective, but no therapy has emerged to leverage this mechanism. METHODS: Mice were fed with either a control diet or a diet enriched with dicarboxylic acids, which are peroxisome-specific FAO substrates, then subjected to either ischemia-reperfusion injury-AKI or cisplatin-AKI models. Biochemical, histologic, genetic, and proteomic analyses were performed. RESULTS: Both octanedioic acid (DC 8 ) and dodecanedioic acid (DC 12 ) prevented the rise of AKI markers in mice that were exposed to renal injury. Proteomics analysis demonstrated that DC 8 preserved the peroxisomal and mitochondrial proteomes while inducing extensive remodeling of the lysine succinylome. This latter finding indicates that DC 8 is chain shortened to the anaplerotic substrate succinate and that peroxisomal FAO was increased by DC 8 . CONCLUSIONS: DC 8 supplementation protects kidney mitochondria and peroxisomes and increases peroxisomal FAO, thereby protecting against AKI.


Asunto(s)
Lesión Renal Aguda , Ácidos Dicarboxílicos , Suplementos Dietéticos , Daño por Reperfusión , Animales , Humanos , Ratones , Lesión Renal Aguda/prevención & control , Lesión Renal Aguda/patología , Cisplatino , Ácidos Dicarboxílicos/administración & dosificación , Ácidos Grasos , Proteómica , Daño por Reperfusión/prevención & control , Daño por Reperfusión/patología
13.
Biochemistry ; 63(14): 1709-1717, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-38975737

RESUMEN

I present the perspective that the divalent metalome and the metabolome can be modeled as a network of chelating interactions instead of separate entities. I review progress in understanding the complex cellular environment, in particular recent contributions to modeling metabolite-Mg2+ interactions. I then demonstrate a simple extension of these strategies based approximately on intracellular Escherichia coli concentrations. This model is composed of four divalent metal cations with a range of cellular concentrations and physical properties (Mg2+, Ca2+, Mn2+, and Zn2+), eight representative metabolites, and interaction constants. I applied this model to predict the speciation of divalent metal cations between free and metabolite-chelated species. This approach reveals potentially beneficial properties, including maintenance of free divalent metal cations at biologically relevant concentrations, buffering of free divalent metal cations, and enrichment of functional metabolite-chelated species. While currently limited by available interaction coefficients, this modeling strategy can be generalized to more complex systems. In summary, biochemists should consider the potential of cellular metabolites to form chelating interactions with divalent metal cations.


Asunto(s)
Cationes Bivalentes , Escherichia coli , Cationes Bivalentes/metabolismo , Cationes Bivalentes/química , Escherichia coli/metabolismo , Escherichia coli/genética , Quelantes/química , Quelantes/metabolismo , Modelos Biológicos , Metaboloma , Magnesio/metabolismo , Magnesio/química , Tampones (Química) , Zinc/metabolismo , Zinc/química
14.
J Am Chem Soc ; 146(22): 15420-15427, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38768558

RESUMEN

We report the strain-induced [2 + 2] cycloadditions of cyclic allenes for the assembly of highly substituted cyclobutanes. By judicious choice of trapping agent, complex scaffolds bearing heteroatoms, fused rings, contiguous stereocenters, spirocycles, and quaternary centers are ultimately accessible. Moreover, we show that the resulting cycloadducts can undergo thermal isomerization. This study provides an alternative strategy to photochemical [2 + 2] cycloadditions for accessing highly functionalized cyclobutanes, while validating the use of underexplored strained intermediates for the assembly of complex architectures.

15.
J Am Chem Soc ; 146(11): 7822-7830, 2024 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-38456811

RESUMEN

Understanding the effects of pressure on actinide compounds is an integral part of safe nuclear waste storage in deep geologic repositories and provides a means of systematically altering the structure and properties. However, detailing how the effects of pressure evolve across the actinide series in the later elements is not typically undertaken because of the challenges of conducting research on these unstable isotopes. Here, a family of bimetallic actinide complexes, [(An(pmtz)2(H2O)3)2(µ-pmtz)]2(pmtz)2·nH2O (An3+ = Cm3+, Bk3+, and Cf3+, pmtz- = 5-(pyrimidyl)tetrazolate; Cm1, Bk1, and Cf1), are reported and represent the first structurally characterized bimetallic berkelium and californium compounds. The pressure response as determined from UV-vis-NIR transitions varies for Cm1, Bk1, and Cf1. The 5f → 5f transitions in Cm1 are notably more sensitive to pressure compared to those in Bk1 and Cf1 and show substantial bathochromic shifting of several 5f → 5f transitions. In the case of Bk1, an ingrowth of a metal-to-ligand charge-transfer transition occurs at elevated pressures because of the accessible Bk3+/Bk4+ couple. For Cf1, no substantial transition shifting or emergence of MLCT transitions is observed at elevated pressures because of the prohibitive energetics of the Cf3+/Cf4+ couple and reduced sensitivity of the 5f → 5f transitions to the local coordination environment because of the more contracted 5f shell versus Cm3+ and Bk3+.

16.
Small ; 20(26): e2308593, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38326100

RESUMEN

Herein, aqueous nitrate (NO3 -) reduction is used to explore composition-selectivity relationships of randomly alloyed ruthenium-palladium nanoparticle catalysts to provide insights into the factors affecting selectivity during this and other industrially relevant catalytic reactions. NO3 - reduction proceeds through nitrite (NO2 -) and then nitric oxide (NO), before diverging to form either dinitrogen (N2) or ammonium (NH4 +) as final products, with N2 preferred in potable water treatment but NH4 + preferred for nitrogen recovery. It is shown that the NO3 - and NO starting feedstocks favor NH4 + formation using Ru-rich catalysts, while Pd-rich catalysts favor N2 formation. Conversely, a NO2 - starting feedstock favors NH4 + at ≈50 atomic-% Ru and selectivity decreases with higher Ru content. Mechanistic differences have been probed using density functional theory (DFT). Results show that, for NO3 - and NO feedstocks, the thermodynamics of the competing pathways for N-H and N-N formation lead to preferential NH4 + or N2 production, respectively, while Ru-rich surfaces are susceptible to poisoning by NO2 - feedstock, which displaces H atoms. This leads to a decrease in overall reduction activity and an increase in selectivity toward N2 production. Together, these results demonstrate the importance of tailoring both the reaction pathway thermodynamics and initial reactant binding energies to control overall reaction selectivity.

17.
Nat Methods ; 18(7): 821-828, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-34127855

RESUMEN

Super-resolution structured illumination microscopy (SIM) has become a widely used method for biological imaging. Standard reconstruction algorithms, however, are prone to generate noise-specific artifacts that limit their applicability for lower signal-to-noise data. Here we present a physically realistic noise model that explains the structured noise artifact, which we then use to motivate new complementary reconstruction approaches. True-Wiener-filtered SIM optimizes contrast given the available signal-to-noise ratio, and flat-noise SIM fully overcomes the structured noise artifact while maintaining resolving power. Both methods eliminate ad hoc user-adjustable reconstruction parameters in favor of physical parameters, enhancing objectivity. The new reconstructions point to a trade-off between contrast and a natural noise appearance. This trade-off can be partly overcome by further notch filtering but at the expense of a decrease in signal-to-noise ratio. The benefits of the proposed approaches are demonstrated on focal adhesion and tubulin samples in two and three dimensions, and on nanofabricated fluorescent test patterns.


Asunto(s)
Procesamiento de Imagen Asistido por Computador/métodos , Microscopía/métodos , Algoritmos , Animales , Línea Celular , Proteínas Fluorescentes Verdes/genética , Humanos , Imagenología Tridimensional/métodos , Ratones , Relación Señal-Ruido , Zixina/análisis , Zixina/genética
18.
PLoS Pathog ; 18(3): e1010396, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35358290

RESUMEN

The CCR5-specific antibody Leronlimab is being investigated as a novel immunotherapy that can suppress HIV replication with minimal side effects. Here we studied the virological and immunological consequences of Leronlimab in chronically CCR5-tropic HIV-1 infected humans (n = 5) on suppressive antiretroviral therapy (ART) and in ART-naïve acutely CCR5-tropic SHIV infected rhesus macaques (n = 4). All five human participants transitioned from daily combination ART to self-administered weekly subcutaneous (SC) injections of 350 mg or 700 mg Leronlimab and to date all participants have sustained virologic suppression for over seven years. In all participants, Leronlimab fully occupied CCR5 receptors on peripheral blood CD4+ T cells and monocytes. In ART-naïve rhesus macaques acutely infected with CCR5-tropic SHIV, weekly SC injections of 50 mg/kg Leronlimab fully suppressed plasma viremia in half of the macaques. CCR5 receptor occupancy by Leronlimab occurred concomitant with rebound of CD4+ CCR5+ T-cells in peripheral blood, and full CCR5 receptor occupancy was found in multiple anatomical compartments. Our results demonstrate that weekly, self-administered Leronlimab was safe, well-tolerated, and efficacious for long-term virologic suppression and should be included in the arsenal of safe, easily administered, longer-acting antiretroviral treatments for people living with HIV-1. Trial Registration: ClinicalTrials.gov Identifiers: NCT02175680 and NCT02355184.


Asunto(s)
Virus de la Inmunodeficiencia de los Simios , Animales , Anticuerpos Monoclonales Humanizados/farmacología , Anticuerpos Anti-VIH , Humanos , Macaca mulatta , Receptores CCR5
19.
Allergy ; 79(6): 1548-1559, 2024 06.
Artículo en Inglés | MEDLINE | ID: mdl-38477552

RESUMEN

BACKGROUND: Skin tape-strips and biopsies are widely used methods for investigating the skin in atopic dermatitis (AD). Biopsies are more commonly used but can cause scarring and pain, whereas tape-strips are noninvasive but sample less tissue. The study evaluated the performance of skin tape-strips and biopsies for studying AD. METHODS: Whole-transcriptome RNA-sequencing was performed on paired tape-strips and biopsies collected from lesional and non-lesional skin from AD patients (n = 7) and non-AD controls (n = 5). RNA yield, mapping efficiency, and differentially expressed genes (DEGs) for the two methods (tape-strip/biopsy) and presence of AD (AD/non-AD) were compared. RESULTS: Tape-strips demonstrated a lower RNA yield (22 vs. 4596 ng) and mapping efficiency to known genes (28% vs. 93%) than biopsies. Gene-expression profiles of paired tape-strips and biopsies demonstrated a medium correlation (R2 = 0.431). Tape-strips and biopsies demonstrated systematic differences in measured expression levels of 6483 genes across both AD and non-AD samples. Tape-strips preferentially detected many itch (CCL3/CCL4/OSM) and immune-response (CXCL8/IL4/IL5/IL22) genes as well as markers of epidermal dendritic cells (CD1a/CD207), while certain cytokines (IL18/IL37), skin-barrier genes (KRT2/FLG2), and dermal fibroblasts markers (COL1A/COL3A) were preferentially detected by biopsies. Tape-strips identified more DEGs between AD and non-AD (3157 DEGs) then biopsies (44 DEGs). Tape-strips also detected higher levels of bacterial mRNA than biopsies. CONCLUSIONS: This study concludes that tape-strips and biopsies each demonstrate respective advantages for measuring gene-expression changes in AD. Thus, the specific skin layers and genes of interest should be considered before selecting either method.


Asunto(s)
Dermatitis Atópica , Piel , Humanos , Dermatitis Atópica/genética , Dermatitis Atópica/patología , Biopsia , Piel/patología , Piel/metabolismo , Femenino , Análisis de Secuencia de ARN , Masculino , Perfilación de la Expresión Génica , Transcriptoma , Adulto , Cinta Quirúrgica , Persona de Mediana Edad
20.
Allergy ; 79(6): 1455-1469, 2024 06.
Artículo en Inglés | MEDLINE | ID: mdl-38265114

RESUMEN

Atopic dermatitis (AD), the most burdensome skin condition worldwide, is influenced by climatic factors and air pollution; however, the impact of increasing climatic hazards on AD remains poorly characterized. Leveraging an existing framework for 10 climatic hazards related to greenhouse gas emissions, we identified 18 studies with evidence for an impact on AD through a systematic search. Most climatic hazards had evidence for aggravation of AD the impact ranged from direct effects like particulate matter-induced AD exacerbations from wildfires to the potential for indirect effects like drought-induced food insecurity and migration. We then created maps comparing the past, present, and future projected burden of climatic hazards to global AD prevalence data. Data are lacking, especially from those regions most likely to experience more climatic hazards. We highlight gaps important for future research: understanding the synergistic impacts of climatic hazards on AD, long-term disease activity, the differential impact on vulnerable populations, and how basic mechanisms explain population-level trends.


Asunto(s)
Cambio Climático , Dermatitis Atópica , Dermatitis Atópica/epidemiología , Dermatitis Atópica/etiología , Humanos , Prevalencia , Contaminación del Aire/efectos adversos , Exposición a Riesgos Ambientales/efectos adversos
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