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1.
Sci Rep ; 14(1): 14860, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38937546

RESUMO

We demonstrate in a proof-of-concept experiment spectral-domain optical coherence tomography where steering of the optical beam that probes the sample in a transverse scan does not make use of any mechanical element. Steering is done with the help of a phase-only spatial light modulator, that introduces a spatially-dependent phase between the two orthogonal polarization components of an optical beam, and some optical elements that control the polarization of light. We demonstrate that making use of the non-mechanical beam steering system considered here, we can reproduce the main traits of imaging with standard OCT that makes use of mechanical-assisted optical beam steering.

3.
J Immunol ; 213(2): 214-225, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38829123

RESUMO

The interactions between chemokines and their receptors, particularly in the context of inflammation, are complex, with individual receptors binding multiple ligands and individual ligands interacting with multiple receptors. In addition, there are numerous reports of simultaneous coexpression of multiple inflammatory chemokine receptors on individual inflammatory leukocyte subtypes. Overall, this has previously been interpreted as redundancy and proposed as a protective mechanism to ensure that the inflammatory response is robust. By contrast, we have hypothesized that the system is not redundant but exquisitely subtle. Our interests relate to the receptors CCR1, CCR2, CCR3, and CCR5, which, together, regulate nonneutrophilic myeloid cell recruitment to inflammatory sites. In this study, we demonstrate that although most murine monocytes exclusively express CCR2, there is a small subpopulation that is expanded during inflammation and coexpresses CCR1 and CCR2. Combinations of transcript and functional analysis demonstrate that this is not redundant expression and that coexpression of CCR1 and CCR2 marks a phenotypically distinct population of monocytes characterized by expression of genes otherwise typically associated with neutrophils. Single-cell RNA sequencing confirms this as a monodisperse population of atypical monocytes. This monocytic population has previously been described as having immunosuppressive activity. Overall, our data confirm combinatorial chemokine receptor expression by a subpopulation of monocytes but demonstrate that this is not redundant expression and marks a discrete monocytic population.


Assuntos
Monócitos , Receptores CCR1 , Receptores CCR2 , Receptores CCR1/genética , Receptores CCR1/metabolismo , Receptores CCR2/genética , Receptores CCR2/metabolismo , Monócitos/imunologia , Monócitos/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Inflamação/imunologia
4.
Purinergic Signal ; 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38879664

RESUMO

The human equilibrative nucleoside transporter 1 (SLC29A1, hENT1) is a solute carrier that modulates the passive transport of nucleosides and nucleobases, such as adenosine. This nucleoside regulates various physiological processes, such as vasodilation and -constriction, neurotransmission and immune defense. Marketed drugs such as dilazep and dipyridamole have proven useful in cardiovascular afflictions, but the application of hENT1 inhibitors can be beneficial in a number of other diseases. In this study, 39 derivatives of dilazep's close analogue ST7092 were designed, synthesized and subsequently assessed using [3H]NBTI displacement assays and molecular docking. Different substitution patterns of the trimethoxy benzoates of ST7092 reduced interactions within the binding pocket, resulting in diminished hENT1 affinity. Conversely, [3H]NBTI displacement by potentially covalent compounds 14b, 14c, and 14d resulted in high affinities (Ki values between 1.1 and 17.5 nM) for the transporter, primarily by the ability of accommodating the inhibitors in various ways in the binding pocket. However, any indication of covalent binding with amino acid residue C439 remained absent, conceivably as a result of decreased nucleophilic residue reactivity. In conclusion, this research introduces novel dilazep derivatives that are active as hENT1 inhibitors, along with the first high affinity dilazep derivatives equipped with an electrophilic warhead. These findings will aid the rational and structure-based development of novel hENT1 inhibitors and pharmacological tools to study hENT1's function, binding mechanisms, and its relevance in (patho)physiological conditions.

6.
Sci Total Environ ; 942: 173808, 2024 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-38848912

RESUMO

High concentrations of microplastic (MP) particles have been reported in the Arctic Ocean. However, studies on the high-resolution lateral and vertical transport of MPs from the European waters to the Arctic are still scarce. Here, we provide information about the concentrations and compositions of MPs in surface, subsurface, and deeper waters (< 1 m, ∼ 4 m, and 17-1679 m) collected at 18 stations on six transects along the Norwegian Coastal Current (NCC) using an improved Neuston Catamaran, the COntinuos MicroPlastic Automatic Sampling System (COMPASS), and in situ pumps, respectively. FTIR microscopy and spectroscopy were applied to measure MP concentration, polymer composition, and size distribution. Results indicate that the concentrations of small microplastics (SMPs, <300 µm) varied considerably (0-1240 MP m-3) within the water column, with significantly higher concentrations in the surface (189 MP m-3) and subsurface (38 MP m-3) waters compared to deeper waters (16 MP m-3). Furthermore, the average concentration of SMPs in surface water samples was four orders of magnitude higher than the abundance of large microplastics (LMPs, >300 µm), and overall, SMPs <50 µm account for >80 % of all detected MPs. However, no statistically significant geographical patterns were observed in SMP concentrations in surface/subsurface seawaters between the six sampling transects, suggesting a relatively homogeneous horizontal distribution of SMPs in the upper ocean within the NCC/Norwegian Atlantic Current (NwAC) interface. The Lagrangian particle dispersal simulation model further enabled us to assess the large-scale transport of MPs from the Northern European waters to the Arctic.

7.
Gastrointest Endosc ; 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38908453

RESUMO

BACKGROUND AND AIMS: Implementation of screening modalities have reduced the burden of colorectal cancer (CRC), but high false positive rates pose a major problem for colonoscopy capacity. We aimed to create a tailored screening algorithm that expands the fecal immunochemical test (FIT) with a blood specimen and current age to improve selection of individuals for diagnostic colonoscopy. METHODS: In this prospective multi-center study, eight blood-based biomarkers (CEA, Ferritin, hsCRP, HE4, Cyfra21-1, Hepsin, IL-8 and OPG) were investigated in 1,977 FIT positive individuals from the Danish national CRC screening program undergoing follow-up colonoscopy. Specimens were analyzed on ARCHITECT i2000®, ARCHITECT c8000® or Luminex xMAP® machines. FIT analyses and blood-based biomarker data were combined with clinical data (i.e., age and colonoscopy findings) in a cross-validated logistic regression model (algorithm) benchmarked against a model solely using the FIT result (FIT model) applying different cutoffs for FIT positivity. RESULTS: The cohort included individuals with CRC (n = 240), adenomas (n = 938) or no neoplastic lesions (n = 799). The cross-validated algorithm combining the eight biomarkers, quantitative FIT result and age performed superior to the FIT model in discriminating CRC versus non-CRC individuals (AUC 0.77 versus 0.67, p < 0.001). When discriminating individuals with either CRC or high- or medium-risk adenomas versus low-risk adenomas or clean colorectum, the AUCs were 0.68 versus 0.64 for the algorithm and FIT model, respectively. CONCLUSIONS: The algorithm presented here can improve patient allocation to colonoscopy, reducing colonoscopy burden without compromising cancer and adenomas detection rates or vice versa.

8.
BMC Geriatr ; 24(1): 527, 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38886640

RESUMO

BACKGROUND: A range of strategies are available that can improve the outcomes of older persons particularly in relation to basic activities of daily living during and after an acute care (AC) episode. This paper outlines the original development of outcome-oriented quality indicators (QIs) in relation to common geriatric syndromes and function for the care of the frail aged hospitalized in acute general medical wards. METHODS: Design QIs were developed using evidence from literature, expert opinion, field study data and a formal voting process. A systematic literature review of literature identified existing QIs (there were no outcome QIs) and evidence of interventions that improve older persons' outcomes in AC. Preliminary indicators were developed by two expert panels following consideration of the evidence. After analysis of the data from field testing (indicator prevalence, variability across sites), panel meetings refined the QIs prior to a formal voting process. SETTING: Data was collected in nine Australian general medical wards. PARTICIPANTS: Patients aged 70 years and over, consented within 24 h of admission to the AC ward. MEASUREMENTS: The interRAI Acute Care - Comprehensive Geriatric Assessment (interRAI AC-CGA) was administered at admission and discharge; a daily risk assessment in hospital; 28-day phone follow-up and chart audit. RESULTS: Ten outcome QIs were established which focused on common geriatric syndromes and function for the care of the frail aged hospitalized in acute general medical wards. CONCLUSION: Ten outcome QIs were developed. These QIs can be used to identify areas where specific action will lead to improvements in the quality of care delivered to older persons in hospital.


Assuntos
Avaliação Geriátrica , Indicadores de Qualidade em Assistência à Saúde , Humanos , Idoso , Indicadores de Qualidade em Assistência à Saúde/normas , Idoso de 80 Anos ou mais , Avaliação Geriátrica/métodos , Feminino , Masculino , Atividades Cotidianas , Hospitalização , Idoso Fragilizado , Avaliação de Resultados da Assistência ao Paciente
9.
ACS Chem Biol ; 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38920052

RESUMO

Small molecular tool compounds play an essential role in the study of G protein-coupled receptors (GPCRs). However, tool compounds most often occupy the orthosteric binding site, hampering the study of GPCRs upon ligand binding. To overcome this problem, ligand-directed labeling techniques have been developed that leave a reporter group covalently bound to the GPCR, while allowing subsequent orthosteric ligands to bind. In this work, we applied such a labeling strategy to the adenosine A2B receptor (A2BAR). We have synthetically implemented the recently reported N-acyl-N-alkyl sulfonamide (NASA) warhead into a previously developed ligand and show that the binding of the A2BAR is not restricted by NASA incorporation. Furthermore, we have investigated ligand-directed labeling of the A2BAR using SDS-PAGE, flow cytometric, and mass spectrometry techniques. We have found one of the synthesized probes to specifically label the A2BAR, although detection was hindered by nonspecific protein labeling most likely due to the intrinsic reactivity of the NASA warhead. Altogether, this work aids the future development of ligand-directed probes for the detection of GPCRs.

10.
Respir Care ; 69(6): 651-663, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38744478

RESUMO

Patients with advanced lung disease, especially patients with COPD, suffer from dyspnea at rest that worsens during the performance of even limited physical activities. The causes of dyspnea are multifactorial and are related to structural changes found in the parenchymal compartment of the lung as well as the airway and pulmonary vasculature. Alterations in any of the lung compartments may have negative consequences for the physiological performance of exercise. Respiratory assist devices that attenuate the pathophysiological derangements induced by the underlying lung disease, and/or unload the increased work of breathing, can enhance the performance of exercise, and help to produce more robust training effects in patients with lung disease. Herein we review the data that examines these approaches using respiratory assist devices to improve exercise outcomes in patients with COPD.


Assuntos
Dispneia , Doença Pulmonar Obstrutiva Crônica , Humanos , Doença Pulmonar Obstrutiva Crônica/reabilitação , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Dispneia/etiologia , Tolerância ao Exercício/fisiologia , Terapia por Exercício/métodos , Terapia por Exercício/instrumentação
12.
JAMA Netw Open ; 7(5): e247535, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38771577

RESUMO

Importance: While ß-blockers are associated with decreased mortality in cardiovascular disease (CVD), exacerbation-prone patients with chronic obstructive pulmonary disease (COPD) who received metoprolol in the Beta-Blockers for the Prevention of Acute Exacerbations of Chronic Obstructive Pulmonary Disease (BLOCK-COPD) trial experienced increased risk of exacerbations requiring hospitalization. However, the study excluded individuals with established indications for the drug, raising questions about the overall risk and benefit in patients with COPD following acute myocardial infarction (AMI). Objective: To investigate whether ß-blocker prescription at hospital discharge is associated with increased risk of mortality or adverse cardiopulmonary outcomes in patients with COPD and AMI. Design, Setting, and Participants: This prospective, longitudinal cohort study with 6 months of follow-up enrolled patients aged 35 years or older with COPD who underwent cardiac catheterization for AMI at 18 BLOCK-COPD network hospitals in the US from June 2020 through May 2022. Exposure: Prescription for any ß-blocker at hospital discharge. Main Outcomes and Measures: The primary outcome was time to the composite outcome of death or all-cause hospitalization or revascularization. Secondary outcomes included death, hospitalization, or revascularization for CVD events, death or hospitalization for COPD or respiratory events, and treatment for COPD exacerbations. Results: Among 3531 patients who underwent cardiac catheterization for AMI, prevalence of COPD was 17.1% (95% CI, 15.8%-18.4%). Of 579 total patients with COPD and AMI, 502 (86.7%) were prescribed a ß-blocker at discharge. Among the 562 patients with COPD included in the final analysis, median age was 70.0 years (range, 38.0-94.0 years) and 329 (58.5%) were male; 553 of the 579 patients (95.5%) had follow-up information. Among those discharged with ß-blockers, there was no increased risk of the primary end point of all-cause mortality, revascularization, or hospitalization (hazard ratio [HR], 1.01; 95% CI, 0.66-1.54; P = .96) or of cardiovascular events (HR, 1.11; 95% CI, 0.65-1.92; P = .69), COPD-related or respiratory events (HR, 0.75; 95% CI, 0.34-1.66; P = .48), or treatment for COPD exacerbations (rate ratio, 1.01; 95% CI, 0.53-1.91; P = .98). Conclusions and Relevance: In this cohort study, ß-blocker prescription at hospital discharge was not associated with increased risk of adverse outcomes in patients with COPD and AMI. These findings support use of ß-blockers in patients with COPD and recent AMI.


Assuntos
Antagonistas Adrenérgicos beta , Infarto do Miocárdio , Doença Pulmonar Obstrutiva Crônica , Humanos , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Doença Pulmonar Obstrutiva Crônica/complicações , Antagonistas Adrenérgicos beta/uso terapêutico , Masculino , Feminino , Infarto do Miocárdio/complicações , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/mortalidade , Idoso , Pessoa de Meia-Idade , Estudos Prospectivos , Estudos Longitudinais , Hospitalização/estatística & dados numéricos
13.
EMBO J ; 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38816652

RESUMO

In mice, γδ-T lymphocytes that express the co-stimulatory molecule, CD27, are committed to the IFNγ-producing lineage during thymic development. In the periphery, these cells play a critical role in host defense and anti-tumor immunity. Unlike αß-T cells that rely on MHC-presented peptides to drive their terminal differentiation, it is unclear whether MHC-unrestricted γδ-T cells undergo further functional maturation after exiting the thymus. Here, we provide evidence of phenotypic and functional diversity within peripheral IFNγ-producing γδ T cells. We found that CD27+ Ly6C- cells convert into CD27+Ly6C+ cells, and these CD27+Ly6C+ cells control cancer progression in mice, while the CD27+Ly6C- cells cannot. The gene signatures of these two subsets were highly analogous to human immature and mature γδ-T cells, indicative of conservation across species. We show that IL-27 supports the cytotoxic phenotype and function of mouse CD27+Ly6C+ cells and human Vδ2+ cells, while IL-27 is dispensable for mouse CD27+Ly6C- cell and human Vδ1+ cell functions. These data reveal increased complexity within IFNγ-producing γδ-T cells, comprising immature and terminally differentiated subsets, that offer new insights into unconventional T-cell biology.

14.
JTCVS Open ; 18: 369-375, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38690414

RESUMO

Background: Bronchoscopic lung volume reduction (BLVR) has supplanted surgery in the treatment of patients with advanced emphysema, but not all patients qualify for it. Our study aimed to investigate the outcomes of lung volume reduction surgery (LVRS) among patients who either failed BLVR or were not candidates for it. Methods: We conducted a retrospective analysis of patients who underwent LVRS for upper lobe-predominant emphysema at a single tertiary center between March 2018 and December 2022. The main outcomes measures were preoperative and postoperative respiratory parameters, perioperative morbidity, and mortality. Results: A total of 67 LVRS recipients were evaluated, including 10 who had failed prior valve placement. The median patient age was 69 years, and 35 (52%) were male. All procedures were performed thoracoscopically, with 36 patients (53.7%) undergoing bilateral LVRS. The median hospital length of stay was 7 days (interquartile range, 6-11 days). Prolonged air leak (>7 days) occurred in 20 patients. There was one 90-day mortality from a nosocomial pneumonia (non-COVID-related) and no further deaths at 12 months. There were mean improvements of 10.07% in forced expiratory volume in 1 second and 4.74% in diffusing capacity of the lung for carbon monoxide, along with a mean decrease 49.2% in residual volume (P < .001 for all). The modified Medical Research Council dyspnea scale was improved by 1.84 points (P < .001). Conclusions: LVRS can be performed safely in patients who are not candidates for BLVR and those who fail BLVR and leads to significant functional improvement. Long-term follow-up is necessary to ensure the sustainability of LVRS benefits in this patient population.

15.
Ir J Med Sci ; 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38578384

RESUMO

BACKGROUND: People who interact with healthcare services have an ethical and legal right to control their own lives, to make informed decisions, and to consent to what happens to them. For consent to be considered ethically and legally valid, three key criteria must be met: consent must be given voluntarily; people must be sufficiently informed of all options; and people should have capacity to make the decision to give or withhold their consent. AIM: This study set out to explore, through the use of surveys, the perspectives of patients and public in relation to consent. METHOD: Surveys were developed for patients and the public and administered paper based (patients) and through social media (public). RESULTS: One hundred and forty surveys were posted to patients, with a 38% response rate; 104 responses were received from the public. Ninety-six percent of patients were satisfied that the decision they made was informed; 100% felt they had made a voluntary decision; 98% felt the clinician seemed knowledgeable about the procedure. What matters most to the public were being informed about the risks associated with the proposed procedure and being assured that whatever choice they make they will receive the best care possible. CONCLUSIONS: The results highlight interesting similarities and differences in relation to consent between members of the public thinking about a possible treatment, surgery, or procedure and those patients who have actually been through the process in the past 12 months. Recommendations have been developed on the basis of these findings to co-design improvements in consent practices.

16.
Respir Med ; 227: 107639, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38642906

RESUMO

Bronchoscopic lung volume reduction treatment with Zephyr one-way valves is an effective guideline-based treatment option for patients with severe emphysema and hyperinflation. However, in some cases the treatment response is less than anticipated or there might be a loss of initial treatment effect. Reasons for the lack of response can include incorrect assessment of collateral ventilation, improper valve placement, or patient related factors. Loss of initial benefit can be due to granulation tissue formation and subsequent valve dysfunction, or there may be side effects such as excessive coughing or infectious problems. Careful follow-up after treatment with valves is important and evaluation with a CT scan and/or bronchoscopy is helpful if there is no improvement after treatment or loss of initial benefit. This paper aims to describe the most important causes and provide a strategy of how to approach and manage these patients.


Assuntos
Broncoscopia , Pneumonectomia , Enfisema Pulmonar , Humanos , Broncoscopia/métodos , Enfisema Pulmonar/cirurgia , Enfisema Pulmonar/fisiopatologia , Pneumonectomia/métodos , Resultado do Tratamento , Tomografia Computadorizada por Raios X
17.
J Clin Oncol ; 42(15): 1799-1809, 2024 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-38640453

RESUMO

PURPOSE: To compare outcomes after laparoscopic versus open major liver resection (hemihepatectomy) mainly for primary or metastatic cancer. The primary outcome measure was time to functional recovery. Secondary outcomes included morbidity, quality of life (QoL), and for those with cancer, resection margin status and time to adjuvant systemic therapy. PATIENTS AND METHODS: This was a multicenter, randomized controlled, patient-blinded, superiority trial on adult patients undergoing hemihepatectomy. Patients were recruited from 16 hospitals in Europe between November 2013 and December 2018. RESULTS: Of the 352 randomly assigned patients, 332 patients (94.3%) underwent surgery (laparoscopic, n = 166 and open, n = 166) and comprised the analysis population. The median time to functional recovery was 4 days (IQR, 3-5; range, 1-30) for laparoscopic hemihepatectomy versus 5 days (IQR, 4-6; range, 1-33) for open hemihepatectomy (difference, -17.5% [96% CI, -25.6 to -8.4]; P < .001). There was no difference in major complications (laparoscopic 24/166 [14.5%] v open 28/166 [16.9%]; odds ratio [OR], 0.84; P = .58). Regarding QoL, both global health status (difference, 3.2 points; P < .001) and body image (difference, 0.9 points; P < .001) scored significantly higher in the laparoscopic group. For the 281 (84.6%) patients with cancer, R0 resection margin status was similar (laparoscopic 106 [77.9%] v open 122 patients [84.1%], OR, 0.60; P = .14) with a shorter time to adjuvant systemic therapy in the laparoscopic group (46.5 days v 62.8 days, hazard ratio, 2.20; P = .009). CONCLUSION: Among patients undergoing hemihepatectomy, the laparoscopic approach resulted in a shorter time to functional recovery compared with open surgery. In addition, it was associated with a better QoL, and in patients with cancer, a shorter time to adjuvant systemic therapy with no adverse impact on cancer outcomes observed.


Assuntos
Hepatectomia , Laparoscopia , Neoplasias Hepáticas , Qualidade de Vida , Humanos , Hepatectomia/métodos , Hepatectomia/efeitos adversos , Laparoscopia/efeitos adversos , Laparoscopia/métodos , Masculino , Feminino , Pessoa de Meia-Idade , Neoplasias Hepáticas/cirurgia , Neoplasias Hepáticas/secundário , Idoso , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/epidemiologia , Adulto , Resultado do Tratamento
18.
Int J Mol Sci ; 25(7)2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38612509

RESUMO

Cancer remains a leading cause of mortality worldwide and calls for novel therapeutic targets. Membrane proteins are key players in various cancer types but present unique challenges compared to soluble proteins. The advent of computational drug discovery tools offers a promising approach to address these challenges, allowing for the prioritization of "wet-lab" experiments. In this review, we explore the applications of computational approaches in membrane protein oncological characterization, particularly focusing on three prominent membrane protein families: receptor tyrosine kinases (RTKs), G protein-coupled receptors (GPCRs), and solute carrier proteins (SLCs). We chose these families due to their varying levels of understanding and research data availability, which leads to distinct challenges and opportunities for computational analysis. We discuss the utilization of multi-omics data, machine learning, and structure-based methods to investigate aberrant protein functionalities associated with cancer progression within each family. Moreover, we highlight the importance of considering the broader cellular context and, in particular, cross-talk between proteins. Despite existing challenges, computational tools hold promise in dissecting membrane protein dysregulation in cancer. With advancing computational capabilities and data resources, these tools are poised to play a pivotal role in identifying and prioritizing membrane proteins as personalized anticancer targets.


Assuntos
Proteínas de Membrana , Neoplasias , Humanos , Reações Cruzadas , Descoberta de Drogas , Aprendizado de Máquina , Neoplasias/tratamento farmacológico
19.
ACS Appl Electron Mater ; 6(2): 1483-1492, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38435802

RESUMO

III-V semiconductor light-emitting diodes (LEDs) are a promising candidate for demonstrating electroluminescent cooling. However, exceptionally high internal quantum efficiency designs are paramount to achieving this goal. A significant loss mechanism preventing unity internal quantum efficiency in GaAs-based devices is nonradiative surface recombination at the perimeter sidewall. To address this issue, an unconventional LED design is presented, in which the distance from the central current injection area to the device's perimeter is extended while maintaining a constant front contact grid size. This approach effectively moves the perimeter beyond the lateral spread of current at an operating current density of 101-102 A/cm2. In p-i-n GaAs/InGaP double heterojunction LEDs fabricated with varying sizes and perimeter extensions, a 19% relative increase in external quantum efficiency is achieved by extending the perimeter-to-contact distance from 25 to 250 µm for a front contact grid size of 450 × 450 µm2. Utilizing an in-house developed Photon Dynamics model, the corresponding relative increase in internal quantum efficiency is estimated to be 5%. These results are ascribed to a significant reduction in perimeter recombination due to a lower perimeter-to-surface area (P/A) ratio. However, in contrast to lowering the P/A ratio by increasing the front contact grid size of LEDs, the present method enables these improvements without affecting the required maximum current density in the microscopic active LED area under the front contact grid. These findings aid in the advancement of electroluminescent cooling in LEDs and could prove useful in other dedicated semiconductor devices where perimeter recombination is limiting.

20.
ACS Chem Neurosci ; 15(7): 1424-1431, 2024 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-38478848

RESUMO

Excitatory amino acid transporters (EAATs) are important regulators of amino acid transport and in particular glutamate. Recently, more interest has arisen in these transporters in the context of neurodegenerative diseases. This calls for ways to modulate these targets to drive glutamate transport, EAAT2 and EAAT3 in particular. Several inhibitors (competitive and noncompetitive) exist to block glutamate transport; however, activators remain scarce. Recently, GT949 was proposed as a selective activator of EAAT2, as tested in a radioligand uptake assay. In the presented research, we aimed to validate the use of GT949 to activate EAAT2-driven glutamate transport by applying an innovative, impedance-based, whole-cell assay (xCELLigence). A broad range of GT949 concentrations in a variety of cellular environments were tested in this assay. As expected, no activation of EAAT3 could be detected. Yet, surprisingly, no biological activation of GT949 on EAAT2 could be observed in this assay either. To validate whether the impedance-based assay was not suited to pick up increased glutamate uptake or if the compound might not induce activation in this setup, we performed radioligand uptake assays. Two setups were utilized; a novel method compared to previously published research, and in a reproducible fashion copying the methods used in the existing literature. Nonetheless, activation of neither EAAT2 nor EAAT3 could be observed in these assays. Furthermore, no evidence of GT949 binding or stabilization of purified EAAT2 could be observed in a thermal shift assay. To conclude, based on experimental evidence in the present study GT949 requires specific assay conditions, which are difficult to reproduce, and the compound cannot simply be classified as an activator of EAAT2 based on the presented evidence. Hence, further research is required to develop the tools needed to identify new EAAT modulators and use their potential as a therapeutic target.


Assuntos
Transportador 2 de Aminoácido Excitatório , Ácido Glutâmico , Transportador 2 de Aminoácido Excitatório/metabolismo , Impedância Elétrica , Ácido Glutâmico/metabolismo , Transporte Biológico , Transportador 3 de Aminoácido Excitatório/metabolismo
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