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Resistance to insulin and insulin-like growth factor 1 (IGF1) in pancreatic ß-cells causes overt diabetes in mice; thus, therapies that sensitize ß-cells to insulin may protect patients with diabetes against ß-cell failure1-3. Here we identify an inhibitor of insulin receptor (INSR) and IGF1 receptor (IGF1R) signalling in mouse ß-cells, which we name the insulin inhibitory receptor (inceptor; encoded by the gene Iir). Inceptor contains an extracellular cysteine-rich domain with similarities to INSR and IGF1R4, and a mannose 6-phosphate receptor domain that is also found in the IGF2 receptor (IGF2R)5. Knockout mice that lack inceptor (Iir-/-) exhibit signs of hyperinsulinaemia and hypoglycaemia, and die within a few hours of birth. Molecular and cellular analyses of embryonic and postnatal pancreases from Iir-/- mice showed an increase in the activation of INSR-IGF1R in Iir-/- pancreatic tissue, resulting in an increase in the proliferation and mass of ß-cells. Similarly, inducible ß-cell-specific Iir-/- knockout in adult mice and in ex vivo islets led to an increase in the activation of INSR-IGF1R and increased proliferation of ß-cells, resulting in improved glucose tolerance in vivo. Mechanistically, inceptor interacts with INSR-IGF1R to facilitate clathrin-mediated endocytosis for receptor desensitization. Blocking this physical interaction using monoclonal antibodies against the extracellular domain of inceptor resulted in the retention of inceptor and INSR at the plasma membrane to sustain the activation of INSR-IGF1R in ß-cells. Together, our findings show that inceptor shields insulin-producing ß-cells from constitutive pathway activation, and identify inceptor as a potential molecular target for INSR-IGF1R sensitization and diabetes therapy.
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Glicemia/metabolismo , Antagonistas da Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Proteínas de Neoplasias/metabolismo , Transdução de Sinais , Animais , Glicemia/análise , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Tamanho Celular , Clatrina/metabolismo , Células Endócrinas/metabolismo , Endocitose , Retículo Endoplasmático/metabolismo , Teste de Tolerância a Glucose , Complexo de Golgi/metabolismo , Humanos , Fator de Crescimento Insulin-Like I/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Lisossomos/metabolismo , Masculino , Proteínas de Membrana , Camundongos , Proteínas de Neoplasias/química , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Tamoxifeno/farmacologiaRESUMO
Zoonotic influenza A viruses of avian origin can cause severe disease in individuals, or even global pandemics, and thus pose a threat to human populations. Waterfowl and shorebirds are believed to be the reservoir for all influenza A viruses, but this has recently been challenged by the identification of novel influenza A viruses in bats1,2. The major bat influenza A virus envelope glycoprotein, haemagglutinin, does not bind the canonical influenza A virus receptor, sialic acid or any other glycan1,3,4, despite its high sequence and structural homology with conventional haemagglutinins. This functionally uncharacterized plasticity of the bat influenza A virus haemagglutinin means the tropism and zoonotic potential of these viruses has not been fully determined. Here we show, using transcriptomic profiling of susceptible versus non-susceptible cells in combination with genome-wide CRISPR-Cas9 screening, that the major histocompatibility complex class II (MHC-II) human leukocyte antigen DR isotype (HLA-DR) is an essential entry determinant for bat influenza A viruses. Genetic ablation of the HLA-DR α-chain rendered cells resistant to infection by bat influenza A virus, whereas ectopic expression of the HLA-DR complex in non-susceptible cells conferred susceptibility. Expression of MHC-II from different bat species, pigs, mice or chickens also conferred susceptibility to infection. Notably, the infection of mice with bat influenza A virus resulted in robust virus replication in the upper respiratory tract, whereas mice deficient for MHC-II were resistant. Collectively, our data identify MHC-II as a crucial entry mediator for bat influenza A viruses in multiple species, which permits a broad vertebrate tropism.
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Quirópteros/virologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Especificidade de Hospedeiro , Vírus da Influenza A/imunologia , Vírus da Influenza A/fisiologia , Zoonoses/imunologia , Zoonoses/virologia , Animais , Proteína 9 Associada à CRISPR , Sistemas CRISPR-Cas , Galinhas/genética , Galinhas/imunologia , Quirópteros/genética , Quirópteros/imunologia , Quirópteros/metabolismo , Feminino , Perfilação da Expressão Gênica , Antígenos HLA-DR/genética , Antígenos HLA-DR/imunologia , Antígenos HLA-DR/metabolismo , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/imunologia , Especificidade de Hospedeiro/genética , Especificidade de Hospedeiro/imunologia , Humanos , Masculino , Camundongos , Camundongos Knockout , Sistema Respiratório/virologia , Suínos/genética , Suínos/imunologia , Tropismo Viral/genética , Tropismo Viral/imunologia , Replicação Viral , Zoonoses/genética , Zoonoses/metabolismoRESUMO
Targeting the alternative complement pathway is an attractive therapeutic strategy given its role in the pathogenesis of immunoglobulin A nephropathy (IgAN). Iptacopan (LNP023) is an oral, proximal alternative complement inhibitor that specifically binds to Factor B. Our randomized, double-blind, parallel-group adaptive Phase 2 study (NCT03373461) enrolled patients with biopsy-confirmed IgAN (within previous three years) with estimated glomerular filtration rates of 30 mL/min/1.73 m2 and over and urine protein 0.75 g/24 hours and over on stable doses of renin angiotensin system inhibitors. Patients were randomized to four iptacopan doses (10, 50, 100, or 200 mg bid) or placebo for either a three-month (Part 1; 46 patients) or a six-month (Part 2; 66 patients) treatment period. The primary analysis evaluated the dose-response relationship of iptacopan versus placebo on 24-hour urine protein-to-creatinine ratio (UPCR) at three months. Other efficacy, safety and biomarker parameters were assessed. Baseline characteristics were generally well-balanced across treatment arms. There was a statistically significant dose-response effect, with 23% reduction in UPCR achieved with iptacopan 200 mg bid (80% confidence interval 8-34%) at three months. UPCR decreased further through six months in iptacopan 100 and 200 mg arms (from a mean of 1.3 g/g at baseline to 0.8 g/g at six months in the 200 mg arm). A sustained reduction in complement biomarker levels including plasma Bb, serum Wieslab, and urinary C5b-9 was observed. Iptacopan was well-tolerated, with no reports of deaths, treatment-related serious adverse events or bacterial infections, and led to strong inhibition of alternative complement pathway activity and persistent proteinuria reduction in patients with IgAN. Thus, our findings support further evaluation of iptacopan in the ongoing Phase 3 trial (APPLAUSE-IgAN; NCT04578834).
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Glomerulonefrite por IGA , Humanos , Glomerulonefrite por IGA/patologia , Resultado do Tratamento , Via Alternativa do Complemento , Fatores Imunológicos/uso terapêutico , Biomarcadores , Método Duplo-CegoRESUMO
BACKGROUND: Complement 3 glomerulopathy (C3G) and immune complex membranoproliferative glomerulonephritis (IC-MPGN) are ultra-rare chronic kidney diseases with an overall poor prognosis, with approximately 40-50% of patients progressing to kidney failure within 10 years of diagnosis. C3G is characterized by a high rate of disease recurrence in the transplanted kidney. However, there is a lack of published data on clinical outcomes in the pediatric population following transplantation. METHODS: In this multicenter longitudinal cohort study of the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN) registry, we compared the post-transplant outcomes of pediatric patients with C3G (n = 17) or IC-MPGN (n = 3) with a matched case-control group (n = 20). RESULTS: Eleven of 20 children (55%) with C3G or IC-MPGN experienced a recurrence within 5 years post-transplant. Patients with C3G or IC-MPGN had a 5-year graft survival of 61.4%, which was significantly (P = 0.029) lower than the 5-year graft survival of 90% in controls; five patients with C3G or IC-MPGN lost their graft due to recurrence during this observation period. Both the 1-year (20%) and the 5-year (42%) rates of biopsy-proven acute rejection episodes were comparable between patients and controls. Complement-targeted therapy with eculizumab, either as prophylaxis or treatment, did not appear to be effective. CONCLUSIONS: These data in pediatric patients with C3G or IC-MPGN show a high risk of post-transplant disease recurrence (55%) and a significantly lower 5-year graft survival compared to matched controls with other primary kidney diseases. These data underscore the need for post-transplant patients for effective and specific therapies that target the underlying disease mechanism.
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The ability to coordinate multiple reactants at the same active site is important for the wide-spread applicability of single-atom catalysis. Model catalysts are ideal to investigate the link between active site geometry and reactant binding, because the structure of single-crystal surfaces can be precisely determined, the adsorbates imaged by scanning tunneling microscopy (STM), and direct comparisons made to density functional theory. In this study, we follow the evolution of Rh1 adatoms and minority Rh2 dimers on Fe3O4(001) during exposure to CO using time-lapse STM at room temperature. CO adsorption at Rh1 sites results exclusively in stable Rh1CO monocarbonyls, because the Rh atom adapts its coordination to create a stable pseudo-square planar environment. Rh1(CO)2 gem-dicarbonyl species are also observed, but these form exclusively through the breakup of Rh2 dimers via an unstable Rh2(CO)3 intermediate. Overall, our results illustrate how minority species invisible to area-averaging spectra can play an important role in catalytic systems, and show that the decomposition of dimers or small clusters can be an avenue to produce reactive, metastable configurations in single-atom catalysis.
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The International Commission on Radiation Units and Measurements recently proposed new operational quantities for external radiation exposure. Among those, the ambient dose is intended to replace the ambient dose equivalent as estimator for the effective dose. Following its definition, the measurement of the ambient dose requires a much more detailed knowledge about the radiation field than the ambient dose equivalent. The implications for radiation protection in aviation concerning galactic cosmic radiation that would follow the adoption of the ambient dose as operational quantity at flight altitudes were investigated in this work using model calculations. It was found that the ambient dose is about 10% higher than the ambient dose equivalent for conditions relevant in commercial aviation and overestimates the effective dose by about 30%.
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Aviação , Radiação Cósmica , Exposição Ocupacional , Monitoramento de Radiação , Aeronaves , Altitude , Exposição Ocupacional/análise , Doses de RadiaçãoRESUMO
CRADLE was a 36-month multicenter study in pediatric (≥1 to <18 years) kidney transplant recipients randomized at 4 to 6 weeks posttransplant to receive everolimus + reduced-exposure tacrolimus (EVR + rTAC; n = 52) with corticosteroid withdrawal at 6-month posttransplant or continue mycophenolate mofetil + standard-exposure TAC (MMF + sTAC; n = 54) with corticosteroids. The incidence of composite efficacy failure (biopsy-proven acute rejection [BPAR], graft loss, or death) at month 36 was 9.8% vs 9.6% (difference: 0.2%; 80% confidence interval: -7.3 to 7.7) for EVR + rTAC and MMF + sTAC, respectively, which was driven by BPARs. Graft loss was low (2.1% vs 3.8%) with no deaths. Mean estimated glomerular filtration rate at month 36 was comparable between groups (68.1 vs 67.3 mL/min/1.73 m2 ). Mean changes (z-score) in height (0.72 vs 0.39; P = .158) and weight (0.61 vs 0.82; P = .453) from randomization to month 36 were comparable, whereas growth in prepubertal patients on EVR + rTAC was better (P = .050) vs MMF + sTAC. The overall incidence of adverse events (AEs) and serious AEs was comparable between groups. Rejection was the leading AE for study drug discontinuation in the EVR + rTAC group. In conclusion, though AE-related study drug discontinuation was higher, an EVR + rTAC regimen represents an alternative treatment option that enables withdrawal of steroids as well as reduction of CNIs for pediatric kidney transplant recipients. ClinicalTrials.gov: NCT01544491.
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Transplante de Rim , Tacrolimo , Criança , Everolimo , Taxa de Filtração Glomerular , Rejeição de Enxerto/tratamento farmacológico , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto , Humanos , Imunossupressores , Transplante de Rim/efeitos adversos , Ácido Micofenólico/uso terapêutico , Esteroides , TransplantadosRESUMO
The June 2, 2018, impact of asteroid 2018 LA over Botswana is only the second asteroid detected in space prior to impacting over land. Here, we report on the successful recovery of meteorites. Additional astrometric data refine the approach orbit and define the spin period and shape of the asteroid. Video observations of the fireball constrain the asteroid's position in its orbit and were used to triangulate the location of the fireball's main flare over the Central Kalahari Game Reserve. 23 meteorites were recovered. A consortium study of eight of these classifies Motopi Pan as a HED polymict breccia derived from howardite, cumulate and basaltic eucrite, and diogenite lithologies. Before impact, 2018 LA was a solid rock of ~156 cm diameter with high bulk density ~2.85 g/cm3, a relatively low albedo pv ~ 0.25, no significant opposition effect on the asteroid brightness, and an impact kinetic energy of ~0.2 kt. The orbit of 2018 LA is consistent with an origin at Vesta (or its Vestoids) and delivery into an Earth-impacting orbit via the v6 resonance. The impact that ejected 2018 LA in an orbit towards Earth occurred 22.8 ± 3.8 Ma ago. Zircons record a concordant U-Pb age of 4563 ± 11 Ma and a consistent 207Pb/206Pb age of 4563 ± 6 Ma. A much younger Pb-Pb phosphate resetting age of 4234 ± 41 Ma was found. From this impact chronology, we discuss what is the possible source crater of Motopi Pan and the age of Vesta's Veneneia impact basin.
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Determining the structure of water adsorbed on solid surfaces is a notoriously difficult task and pushes the limits of experimental and theoretical techniques. Here, we follow the evolution of water agglomerates on Fe3O4(001); a complex mineral surface relevant in both modern technology and the natural environment. Strong OH-H2O bonds drive the formation of partially dissociated water dimers at low coverage, but a surface reconstruction restricts the density of such species to one per unit cell. The dimers act as an anchor for further water molecules as the coverage increases, leading first to partially dissociated water trimers, and then to a ring-like, hydrogen-bonded network that covers the entire surface. Unraveling this complexity requires the concerted application of several state-of-the-art methods. Quantitative temperature-programmed desorption (TPD) reveals the coverage of stable structures, monochromatic X-ray photoelectron spectroscopy (XPS) shows the extent of partial dissociation, and noncontact atomic force microscopy (AFM) using a CO-functionalized tip provides a direct view of the agglomerate structure. Together, these data provide a stringent test of the minimum-energy configurations determined via a van der Waals density functional theory (DFT)-based genetic search.
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In a 12-month, multicenter, open-label study, 106 children were randomized at 4 to 6 weeks after kidney transplantation to switch to everolimus with reduced TAC (EVR/rTAC) and steroid elimination from month 5 posttransplant or to continue standard tacrolimus with mycophenolate mofetil (sTAC/MMF) and steroids. The cumulative incidence of a co-primary efficacy end point (biopsy-proven acute rejection [BPAR], graft loss, or death from randomization to month 12) was 10.3% with EVR/rTAC and 5.8% with sTAC/MMF (difference 4.4%; P = .417). BPAR occurred in 9.6% and 5.6% of patients, respectively. Patient and renal allograft survival were 100%. The co-primary end point of mean estimated glomerular filtration rate at month 12 was 76.2 mL/min/1.73 m2 with EVR/rTAC and 72.5 mL/min/1.73 m2 for sTAC/MMF (difference 3.8 mL/min/1.73m2 ; P = .49). One EVR/rTAC patient developed posttransplant lymphoproliferative disease. Longitudinal growth and sexual maturation were equivalent between groups. The randomized drug regimen was discontinued in 34.6% and 13% of patients in the EVR/rTAC and sTAC/MMF groups, respectively (P = .024), and discontinued due to adverse events/infections in 25.0% and 11.1% of patients (P = .062). In conclusion, early conversion of pediatric kidney transplant patients from TAC, MMF, and steroids to EVR/rTAC and steroid withdrawal maintains immunosuppressive efficacy and preserves renal function.
Assuntos
Rejeição de Enxerto/tratamento farmacológico , Imunossupressores/uso terapêutico , Falência Renal Crônica/cirurgia , Transplante de Rim/efeitos adversos , Complicações Pós-Operatórias/prevenção & controle , Suspensão de Tratamento/estatística & dados numéricos , Adolescente , Criança , Pré-Escolar , Everolimo/uso terapêutico , Feminino , Seguimentos , Taxa de Filtração Glomerular , Rejeição de Enxerto/etiologia , Rejeição de Enxerto/patologia , Sobrevivência de Enxerto , Humanos , Lactente , Testes de Função Renal , Masculino , Ácido Micofenólico/uso terapêutico , Prognóstico , Fatores de Risco , Esteroides/uso terapêutico , Tacrolimo/uso terapêuticoRESUMO
Padlock probes are single-stranded DNA molecules that are circularized upon hybridization to their target sequence by a DNA ligase. In the following, the circulated padlock probes are amplified and detected with fluorescently labeled probes complementary to the amplification product. The hallmark of padlock probe assays is a high detection specificity gained by the ligation reaction. Concomitantly, the ligation reaction is the largest drawback for a quantitative in situ detection of mRNAs due to the low affinities of common DNA or RNA ligases to RNA-DNA duplex strands. Therefore, current protocols require that mRNAs be reverse transcribed to DNA before detection with padlock probes. Recently, it was found that the DNA ligase from Paramecium bursaria Chlorella virus 1 (PBCV-1) is able to efficiently ligate RNA-splinted DNA. Hence, we designed a padlock probe assay for direct in situ detection of mRNAs using the PBCV-1 DNA ligase. Experimental single-cell data were used to optimize and characterize the efficiency of mRNA detection with padlock probes. Our results demonstrate that the PBCV-1 DNA ligase overcomes the efficiency limitation of current protocols for direct in situ mRNA detection, making the PBCV-1 DNA ligase an attractive tool to simplify in situ ligation sequencing applications.
Assuntos
DNA Ligases/química , Sondas de DNA/química , DNA de Cadeia Simples/química , Hibridização In Situ/métodos , Hibridização de Ácido Nucleico/métodos , RNA Mensageiro/análise , Proteínas Virais/química , Actinas/análise , Actinas/genética , Actinas/metabolismo , Pareamento de Bases , Fixadores/química , Corantes Fluorescentes/química , Formaldeído/química , Expressão Gênica , Células HeLa , Humanos , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Célula Única/métodos , Fixação de TecidosRESUMO
The extraction of directional motion information from changing retinal images is one of the earliest and most important processing steps in any visual system. In the fly optic lobe, two parallel processing streams have been anatomically described, leading from two first-order interneurons, L1 and L2, via T4 and T5 cells onto large, wide-field motion-sensitive interneurons of the lobula plate. Therefore, T4 and T5 cells are thought to have a pivotal role in motion processing; however, owing to their small size, it is difficult to obtain electrical recordings of T4 and T5 cells, leaving their visual response properties largely unknown. We circumvent this problem by means of optical recording from these cells in Drosophila, using the genetically encoded calcium indicator GCaMP5 (ref. 2). Here we find that specific subpopulations of T4 and T5 cells are directionally tuned to one of the four cardinal directions; that is, front-to-back, back-to-front, upwards and downwards. Depending on their preferred direction, T4 and T5 cells terminate in specific sublayers of the lobula plate. T4 and T5 functionally segregate with respect to contrast polarity: whereas T4 cells selectively respond to moving brightness increments (ON edges), T5 cells only respond to moving brightness decrements (OFF edges). When the output from T4 or T5 cells is blocked, the responses of postsynaptic lobula plate neurons to moving ON (T4 block) or OFF edges (T5 block) are selectively compromised. The same effects are seen in turning responses of tethered walking flies. Thus, starting with L1 and L2, the visual input is split into separate ON and OFF pathways, and motion along all four cardinal directions is computed separately within each pathway. The output of these eight different motion detectors is then sorted such that ON (T4) and OFF (T5) motion detectors with the same directional tuning converge in the same layer of the lobula plate, jointly providing the input to downstream circuits and motion-driven behaviours.
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Drosophila/fisiologia , Percepção de Movimento/fisiologia , Vias Visuais/fisiologia , Animais , Comportamento Animal/fisiologia , Drosophila/citologia , Interneurônios/fisiologia , Locomoção/fisiologia , Neurônios/fisiologia , Transdução de Sinais , Vias Visuais/citologiaRESUMO
Atomic-scale investigations of metal oxide surfaces exposed to aqueous environments are vital to understand degradation phenomena (e.g., dissolution and corrosion) as well as the performance of these materials in applications. Here, we utilize a new experimental setup for the ultrahigh vacuum-compatible dosing of liquids to explore the stability of the Fe3O4(001)-(â2 × â2)R45° surface following exposure to liquid and ambient pressure water. X-ray photoelectron spectroscopy and low-energy electron diffraction data show that extensive hydroxylation causes the surface to revert to a bulklike (1 × 1) termination. However, scanning tunneling microscopy (STM) images reveal a more complex situation, with the slow growth of an oxyhydroxide phase, which ultimately saturates at approximately 40% coverage. We conclude that the new material contains OH groups from dissociated water coordinated to Fe cations extracted from subsurface layers and that the surface passivates once the surface oxygen lattice is saturated with H because no further dissociation can take place. The resemblance of the STM images to those acquired in previous electrochemical STM studies leads us to believe that a similar structure exists at the solid-electrolyte interface during immersion at pH 7.
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Mammalian target of rapamycin (mTOR) is a central kinase integrating nutrient, energy, and metabolite signals. The kinase forms two distinct complexes: mTORC1 and mTORC2. mTORC1 plays an essential but undefined regulatory function for regeneration of adipose tissue. Analysis of mTOR in general is hampered by the complexity of regulatory mechanisms, including protein interactions and/or phosphorylation, in an ever-changing cellular microenvironment. Here, we developed a microfluidic large-scale integration chip platform for culturing and differentiating human adipose-derived stem cells (hASCs) in 128 separated microchambers under standardized nutrient conditions over 3 wk. The progression of the stem cell differentiation was measured by determining the lipid accumulation rates in hASC cultures. For in situ protein analytics, we developed a multiplex in situ proximity ligation assay (mPLA) that can detect mTOR in its two complexes selectively in single cells and implemented it on the same chip. With this combined technology, it was possible to reveal that the mTORC1 is regulated in its abundance, phosphorylation state, and localization in coordination with lysosomes during adipogenesis. High-content image analysis and parameterization of the in situ PLA signals in over 1 million cells cultured on four individual chips showed that mTORC1 and lysosomes are temporally and spatially coordinated but not in its composition during adipogenesis.
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Adipogenia/fisiologia , Células-Tronco Adultas/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Células Cultivadas , Humanos , Dispositivos Lab-On-A-Chip , Lisossomos/metabolismoRESUMO
In their most recent recommendations, the International Commission on Radiological Protection (ICRP) proposed the use of a set of updated tissue and radiation weighting factors for the calculation of the effective dose. This recommendation was adopted in the European Union by the directive 2013/59/EURATOM in 2013 and implemented in the corresponding radiation protection regulations in Germany in 2018. In this study, we investigate the impact of the new weighting factors according to ICRP 103 on the dose rates of the effective dose due to the exposure of aircrew to cosmic radiation with the PANDOCA model for the description of the complex radiation field in the atmosphere. The application of the updated weighting factors leads to a reduction in the rate of the effective dose in the order of 20% to 30% depending on atmospheric and geomagnetic shielding as well as solar modulation.
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Aeronaves , Radiação Cósmica , Exposição Ocupacional/análise , Doses de Radiação , Monitoramento de Radiação/normas , Humanos , Agências Internacionais , Proteção Radiológica/métodos , Fatores de RiscoRESUMO
Ultraviolet radiation (UVR) is significantly higher at aviation altitudes with respect to sea level. Cockpit windshields protect pilots from UV-B radiation but studies have shown that this is not necessarily the case for UV-A radiation. This work investigates the spectral properties of several windshields under flight conditions. Only one of the investigated windshields showed good UV-A attenuation. Furthermore, the altitude dependence of UV-A irradiance behind a windshield was measured with high spatial resolution. Measurements of the maximal UV irradiance behind the windshield surfaces and at the pilot's position are compared to the recommendations by the International Commission on Non-Ionising Radiation Protection. Some recommended limits were exceeded at the surface of the windshields with direct sunlight and a large field of view. At the pilot's position, with a more realistic field of view, the unweighted recommended level could have been exceeded within tens of minutes by looking in the direction of the Sun without visor or other protective measures. The weighted recommended maximal UVR exposure was not exceeded, neither with the use of the visor at the pilot's position nor without it. The use of the visor for filtering direct sunlight was very effective in terms of UV-A reduction.
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Aeronaves , Proteção Radiológica , Raios Ultravioleta , Altitude , RadiometriaRESUMO
Single-atom catalysts (SACs) bridge homo- and heterogeneous catalysis because the active site is a metal atom coordinated to surface ligands. The local binding environment of the atom should thus strongly influence how reactants adsorb. Now, atomically resolved scanning-probe microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, and DFT are used to study how CO binds at different Ir1 sites on a precisely defined Fe3 O4 (001) support. The two- and five-fold-coordinated Ir adatoms bind CO more strongly than metallic Ir, and adopt structures consistent with square-planar IrI and octahedral IrIII complexes, respectively. Ir incorporates into the subsurface already at 450â K, becoming inactive for adsorption. Above 900â K, the Ir adatoms agglomerate to form nanoparticles encapsulated by iron oxide. These results demonstrate the link between SAC systems and coordination complexes, and that incorporation into the support is an important deactivation mechanism.
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The Community Coordinated Modeling Center has been leading community-wide space science and space weather model validation projects for many years. These efforts have been broadened and extended via the newly launched International Forum for Space Weather Modeling Capabilities Assessment (https://ccmc.gsfc.nasa.gov/assessment/). Its objective is to track space weather models' progress and performance over time, a capability that is critically needed in space weather operations and different user communities in general. The Space Radiation and Plasma Effects Working Team of the aforementioned International Forum works on one of the many focused evaluation topics and deals with five different subtopics (https://ccmc.gsfc.nasa.gov/assessment/topics/radiation-all.php) and varieties of particle populations: Surface Charging from tens of eV to 50-keV electrons and internal charging due to energetic electrons from hundreds keV to several MeVs. Single-event effects from solar energetic particles and galactic cosmic rays (several MeV to TeV), total dose due to accumulation of doses from electrons (>100 keV) and protons (>1 MeV) in a broad energy range, and radiation effects from solar energetic particles and galactic cosmic rays at aviation altitudes. A unique aspect of the Space Radiation and Plasma Effects focus area is that it bridges the space environments, engineering, and user communities. The intent of the paper is to provide an overview of the current status and to suggest a guide for how to best validate space environment models for operational/engineering use, which includes selection of essential space environment and effect quantities and appropriate metrics.
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Diabetic nephropathy is the main cause of end-stage renal disease. MicroRNAs are powerful regulators of the genome, and global expression profiling revealed miR-21 to be among the most highly regulated microRNAs in kidneys of mice with diabetic nephropathy. In kidney biopsies of diabetic patients, miR-21 correlated with tubulointerstitial injury. In situ PCR analysis showed a specific enrichment of miR-21 in glomerular cells. We identified cell division cycle 25a (Cdc25a) and cyclin-dependent kinase 6 (Cdk6) as novel miR-21 targets in mesangial cells. miR-21-mediated repression of Cdc25a and Cdk6 resulted in impaired cell cycle progression and subsequent mesangial cell hypertrophy. miR-21 increased podocyte motility by regulating phosphatase and tensin homolog (Pten). miR-21 antagonism in vitro and in vivo in streptozotocin-induced diabetic mice decreased mesangial expansion, interstitial fibrosis, macrophage infiltration, podocyte loss, albuminuria, and fibrotic- and inflammatory gene expression. In conclusion, miR-21 antagonism rescued various functional and structural parameters in mice with diabetic nephropathy and, thus, might be a viable option in the treatment of patients with diabetic kidney disease.