RESUMO
Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling.
Assuntos
Proteínas de Transporte/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Autofagia/efeitos dos fármacos , Proteínas de Transporte/química , Proteínas de Transporte/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Metionina/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mutagênese Sítio-Dirigida , Fosforilação , Ligação Proteica , Domínios Proteicos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Transdução de Sinais/efeitos dos fármacos , Sirolimo/farmacologiaRESUMO
Autophagy is a process of cellular self-digestion induced by various forms of starvation. Although nitrogen deficit is a common trigger, some yeast cells induce autophagy upon switch from a rich to minimal media without nitrogen starvation. We show that the amino acid methionine is sufficient to inhibit such non-nitrogen-starvation (NNS)-induced autophagy. Methionine boosts synthesis of the methyl donor, S-adenosylmethionine (SAM). SAM inhibits autophagy and promotes growth through the action of the methyltransferase Ppm1p, which modifies the catalytic subunit of PP2A in tune with SAM levels. Methylated PP2A promotes dephosphorylation of Npr2p, a component of a conserved complex that regulates NNS autophagy and other growth-related processes. Thus, methionine and SAM levels represent a critical gauge of amino acid availability that is sensed via the methylation of PP2A to reciprocally regulate cell growth and autophagy.
Assuntos
Autofagia , Metionina/metabolismo , Proteína Fosfatase 2/metabolismo , S-Adenosilmetionina/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Metilação , Proteínas Metiltransferases/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
Protein translation is an energetically demanding process that must be regulated in response to changes in nutrient availability. Herein, we report that intracellular methionine and cysteine availability directly controls the thiolation status of wobble-uridine (U34) nucleotides present on lysine, glutamine, or glutamate tRNAs to regulate cellular translational capacity and metabolic homeostasis. tRNA thiolation is important for growth under nutritionally challenging environments and required for efficient translation of genes enriched in lysine, glutamine, and glutamate codons, which are enriched in proteins important for translation and growth-specific processes. tRNA thiolation is downregulated during sulfur starvation in order to decrease sulfur consumption and growth, and its absence leads to a compensatory increase in enzymes involved in methionine, cysteine, and lysine biosynthesis. Thus, tRNA thiolation enables cells to modulate translational capacity according to the availability of sulfur amino acids, establishing a functional significance for this conserved tRNA nucleotide modification in cell growth control.
Assuntos
Aminoácidos Sulfúricos/metabolismo , Biossíntese de Proteínas , RNA de Transferência/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Uridina/metabolismo , Regulação para Baixo , RNA de Transferência/química , Saccharomyces cerevisiae/crescimento & desenvolvimentoRESUMO
Spatiotemporal regulation of cell type-specific gene expression is essential to convert a zygote into a complex organism that contains hundreds of distinct cell types. A class of cis-regulatory elements called enhancers, which have the potential to enhance target gene transcription, are crucial for precise gene expression programs during development. Following decades of research, many enhancers have been discovered and how enhancers become activated has been extensively studied. However, the mechanisms underlying enhancer silencing are less well understood. We review current understanding of enhancer decommissioning and dememorization, both of which enable enhancer silencing. We highlight recent progress from genome-wide perspectives that have revealed the life cycle of enhancers and how its dynamic regulation underlies cell fate transition, development, cell regeneration, and epigenetic reprogramming.
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Elementos Facilitadores Genéticos , Estágios do Ciclo de Vida , Animais , Diferenciação CelularRESUMO
Oxidative stress, which can be activated by a variety of environmental risk factors, has been implicated as an important pathogenic factor for inflammatory bowel disease (IBD). However, how oxidative stress drives IBD onset remains elusive. Here, we found that oxidative stress was strongly activated in inflamed tissues from both ulcerative colitis patients and Crohn's disease patients, and it caused nuclear-to-cytosolic TDP-43 transport and a reduction in the TDP-43 protein level. To investigate the function of TDP-43 in IBD, we inducibly deleted exons 2 to 3 of Tardbp (encoding Tdp-43) in mouse intestinal epithelium, which disrupted its nuclear localization and RNA-processing function. The deletion gave rise to spontaneous intestinal inflammation by inducing epithelial cell necroptosis. Suppression of the necroptotic pathway with deletion of Mlkl or the RIP1 inhibitor Nec-1 rescued colitis phenotypes. Mechanistically, disruption of nuclear TDP-43 caused excessive R-loop accumulation, which triggered DNA damage and genome instability and thereby induced PARP1 hyperactivation, leading to subsequent NAD+ depletion and ATP loss, consequently activating mitochondrion-dependent necroptosis in intestinal epithelial cells. Importantly, restoration of cellular NAD+ levels with NAD+ or NMN supplementation, as well as suppression of ALKBH7, an α-ketoglutarate dioxygenase in mitochondria, rescued TDP-43 deficiency-induced cell death and intestinal inflammation. Furthermore, TDP-43 protein levels were significantly inversely correlated with γ-H2A.X and p-MLKL levels in clinical IBD samples, suggesting the clinical relevance of TDP-43 deficiency-induced mitochondrion-dependent necroptosis. Taken together, these findings identify a unique pathogenic mechanism that links oxidative stress to intestinal inflammation and provide a potent and valid strategy for IBD intervention.
Assuntos
Doenças Inflamatórias Intestinais , Necroptose , Humanos , Animais , Camundongos , NAD/metabolismo , Estruturas R-Loop , Doenças Inflamatórias Intestinais/metabolismo , Células Epiteliais/metabolismo , Mucosa Intestinal/metabolismo , Inflamação/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Mitocôndrias/metabolismoRESUMO
Although elevated glycolysis has been widely recognized as a hallmark for highly proliferating cells like stem cells and cancer, its regulatory mechanisms are still being updated. Here, we found a previously unappreciated mechanism of mammalian target of rapamycin complex 2 (mTORC2) in regulating glycolysis in intestinal stem cell maintenance and cancer progression. mTORC2 key subunits expression levels and its kinase activity were specifically upregulated in intestinal stem cells, mouse intestinal tumors, and human colorectal cancer (CRC) tissues. Genetic ablation of its key scaffolding protein Rictor in both mouse models and cell lines revealed that mTORC2 played an important role in promoting intestinal stem cell proliferation and self-renewal. Moreover, utilizing mouse models and organoid culture, mTORC2 loss of function was shown to impair growth of gut adenoma and tumor organoids. Based on these findings, we performed RNA-seq and noticed significant metabolic reprogramming in Rictor conditional knockout mice. Among all the pathways, carbohydrate metabolism was most profoundly altered, and further studies demonstrated that mTORC2 promoted glycolysis in intestinal epithelial cells. Most importantly, we showed that a rate-limiting enzyme in regulating glycolysis, 6-phosphofructo-2-kinase (PFKFB2), was a direct target for the mTORC2-AKT signaling. PFKFB2 was phosphorylated upon mTORC2 activation, but not mTORC1, and this process was AKT-dependent. Together, this study has identified a novel mechanism underlying mTORC2 activated glycolysis, offering potential therapeutic targets for treating CRC.
Assuntos
Neoplasias , Proteínas Proto-Oncogênicas c-akt , Animais , Humanos , Camundongos , Modelos Animais de Doenças , Células Epiteliais , Glicólise , Mamíferos , Alvo Mecanístico do Complexo 2 de Rapamicina , Camundongos Knockout , Fosfofrutoquinase-2 , SirolimoRESUMO
Testicular nuclear receptor 4 (TR4) modulates the transcriptional activation of genes and plays important roles in many diseases. The regulation of TR4 on target genes involves direct interactions with DNA molecules via the DNA-binding domain (DBD) and recruitment of coregulators by the ligand-binding domain (LBD). However, their regulatory mechanisms are unclear. Here, we report high-resolution crystal structures of TR4DBD, TR4DBD-DNA complexes and the TR4LBD-JAZF1 complex. For DNA recognition, multiple factors come into play, and a specific mutual selectivity between TR4 and target genes is found. The coactivators SRC-1 and CREBBP can bind at the interface of TR4 originally occupied by the TR4 activation function region 2 (AF-2); however, JAZF1 suppresses the binding through a novel mechanism. JAZF1 binds to an unidentified surface of TR4 and stabilizes an α13 helix never reported in the nuclear receptor family. Moreover, the cancer-associated mutations affect the interactions and the transcriptional activation of TR4 in vitro and in vivo, respectively. Overall, our results highlight the crucial role of DNA recognition and a novel mechanism of how JAZF1 reinforces the autorepressed conformation and influences the transcriptional activation of TR4, laying out important structural bases for drug design for a variety of diseases, including diabetes and cancers.
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Proteínas Correpressoras , Regulação da Expressão Gênica , Receptores de Esteroides , Humanos , Proteínas de Transporte/genética , Proteínas Correpressoras/metabolismo , DNA , Proteínas de Ligação a DNA/genética , Receptores de Esteroides/química , Receptores de Esteroides/metabolismo , Ativação TranscricionalRESUMO
Taxane-induced peripheral neuropathy (TIPN) is a devastating survivorship issue for many cancer patients. In addition to its impact on quality of life, this toxicity may lead to dose reductions or treatment discontinuation, adversely impacting survival outcomes and leading to health disparities in African Americans (AA). Our lab has previously identified deleterious mutations in SET-Binding Factor 2 (SBF2) that significantly associated with severe TIPN in AA patients. Here, we demonstrate the impact of SBF2 on taxane-induced neuronal damage using an ex vivo model of SBF2 knockdown of induced pluripotent stem cell-derived sensory neurons. Knockdown of SBF2 exacerbated paclitaxel changes to cell viability and neurite outgrowth while attenuating paclitaxel-induced sodium current inhibition. Our studies identified paclitaxel-induced expression changes specific to mature sensory neurons and revealed candidate genes involved in the exacerbation of paclitaxel-induced phenotypes accompanying SBF2 knockdown. Overall, these findings provide ex vivo support for the impact of SBF2 on the development of TIPN and shed light on the potential pathways involved.
Assuntos
Paclitaxel/efeitos adversos , Doenças do Sistema Nervoso Periférico/genética , Polimorfismo de Nucleotídeo Único , Proteínas Tirosina Fosfatases não Receptoras/genética , Células Receptoras Sensoriais/citologia , Negro ou Afro-Americano/genética , Sobrevivência Celular/efeitos dos fármacos , Progressão da Doença , Feminino , Técnicas de Silenciamento de Genes , Humanos , Células-Tronco Pluripotentes Induzidas/química , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Paclitaxel/farmacologia , Doenças do Sistema Nervoso Periférico/induzido quimicamente , Doenças do Sistema Nervoso Periférico/etnologia , Qualidade de Vida , Células Receptoras Sensoriais/química , Células Receptoras Sensoriais/efeitos dos fármacos , Análise de Sequência de RNA , Análise de Célula Única , População Branca/genéticaRESUMO
Gallbladder cancer is a rare but fatal malignancy. However, the mechanisms underlying gallbladder carcinogenesis and its progression are poorly understood. The function of m6A modification and its regulators was still unclear for gallbladder cancer. The current study seeks to investigate the function of YTH m6A RNA-binding protein 1 (YTHDF1) in gallbladder cancer. Transcriptomic analysis and immunochemical staining of YTHDF1 in gallbladder cancer tissues revealed its upregulation compared to paracancerous tissues. Moreover, YTHDF1 promotes the proliferation assays, Transwell migration assays, and Transwell invasion assays of gallbladder cancer cells in vitro. And it also increased tumour growth in xenograft mouse model and metastases in tail vein injection model in vivo. In vitro, UHRF1 knockdown partly reversed the effects of YTHDF1 overexpression. Mechanistically, dual-luciferase assays proved that YTHDF1 promotes UHRF1 expression via direct binding to the mRNA 3'-UTR in a m6A-dependent manner. Overexpression of YTHDF1 enhanced UHRF1 mRNA stability, as demonstrated by mRNA stability assays, and Co-IP studies confirmed a direct interaction between YTHDF1 and PABPC1. Collectively, these findings provide new insights into the progression of gallbladder cancer as well as a novel post-transcriptional mechanism of YTHDF1 via stabilizing target mRNA.
Assuntos
Adenosina , Neoplasias da Vesícula Biliar , Regulação Neoplásica da Expressão Gênica , Proteínas de Ligação a RNA , Ubiquitina-Proteína Ligases , Animais , Feminino , Humanos , Masculino , Camundongos , Adenosina/análogos & derivados , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Proteínas Estimuladoras de Ligação a CCAAT/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Progressão da Doença , Neoplasias da Vesícula Biliar/genética , Neoplasias da Vesícula Biliar/patologia , Neoplasias da Vesícula Biliar/metabolismo , Camundongos Nus , Estabilidade de RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
Iron (Fe) is an indispensable trace mineral element for the normal growth of plants, and it is involved in different biological processes; Fe shortage in plants can induce chlorosis and yield loss. The objective of this research is to identify novel genes that participated in the regulation of Fe-deficiency stress in Arabidopsis thaliana. A basic helix-loop-helix (bHLH) transcription factor (MYC1) was identified to be interacting with the FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) using a yeast-two-hybrid assay. Transcript-level analysis showed that there was a decrease in MYC1 expression in Arabidopsis to cope with Fe-deficiency stress. Functional deficiency of MYC1 in Arabidopsis leads to an increase in Fe-deficiency tolerance and Fe-accumulation, whereas MYC1-overexpressing plants have an enhanced sensitivity to Fe-deficiency stress. Additionally, MYC1 inhibited the formation of FIT and bHLH38/39 heterodimers, which suppressed the expressed level for Fe acquisition genes FRO2 and IRT1 during Fe-deficiency stress. These results showed that MYC1 functions as a negative modulator of the Fe-deficiency stress response by inhibiting the formation of FIT and bHLH38/39 heterodimers, thereby suppressing the binding of FIT and bHLH38/39 heterodimers to the promoters of FRO2 and IRT1 to modulate Fe intake during Fe-deficiency stress. Overall, the findings of this study elucidated the role of MYC1 in coping with Fe-deficiency stress, and provided potential targets for the developing of crop varieties resistant to Fe-deficiency stress.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Homeostase/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Raízes de Plantas/metabolismoRESUMO
BACKGROUND: Hepatic encephalopathy (HE) is closely associated with inflammatory responses. However, as a crucial regulator of the immune and inflammatory responses, the role of leucine-rich repeat kinase 2 (LRRK2) in the pathogenesis of HE remains unraveled. Herein, we investigated this issue in thioacetamide (TAA)-induced HE following acute liver failure (ALF). METHODS: TAA-induced HE mouse models of LRRK2 wild type (WT), LRRK2 G2019S mutation (Lrrk2G2019S) and LRRK2 knockout (Lrrk2-/-) were established. A battery of neurobehavioral experiments was conducted. The biochemical indexes and pro-inflammatory cytokines were detected. The prefrontal cortex (PFC), striatum (STR), hippocampus (HIP), and liver were examined by pathology and electron microscopy. The changes of autophagy-lysosomal pathway and activity of critical Rab GTPases were analyzed. RESULTS: The Lrrk2-/--HE model reported a significantly lower survival rate than the other two models (24% vs. 48%, respectively, p < 0.05), with no difference found between the WT-HE and Lrrk2G2019S-HE groups. Compared with the other groups, after the TAA injection, the Lrrk2-/- group displayed a significant increase in ammonium and pro-inflammatory cytokines, aggravated hepatic inflammation/necrosis, decreased autophagy, and abnormal phosphorylation of lysosomal Rab10. All three models reported microglial activation, neuronal loss, disordered vesicle transmission, and damaged myelin structure. The Lrrk2-/--HE mice presented no severer neuronal injury than the other genotypes. CONCLUSIONS: LRRK2 deficiency may exacerbate TAA-induced ALF and HE in mice, in which inflammatory response is evident in the brain and aggravated in the liver. These novel findings indicate a need of sufficient clinical awareness of the adverse effects of LRRK2 inhibitors on the liver.
Assuntos
Encefalopatia Hepática , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina , Falência Hepática Aguda , Camundongos Knockout , Tioacetamida , Animais , Camundongos , Encefalopatia Hepática/patologia , Encefalopatia Hepática/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Falência Hepática Aguda/induzido quimicamente , Falência Hepática Aguda/patologia , Falência Hepática Aguda/genética , Camundongos Endogâmicos C57BL , Tioacetamida/toxicidadeRESUMO
Chediak-Higashi syndrome (CHS) is a rare autosomal recessive genetic disorder characterized by severe immunodeficiency, albinism and coagulation deficiency. Mostly diagnosed in early childhood, this devastating condition is associated with lysosomal abnormalities attributed to the absence or impaired function of lysosomal trafficking regulator caused by mutations in the CHS1/LYST gene. In current study, we report a case of late-onset CHS caused by two novel compound heterozygous CHS1/LYST mutations: c.8407C > T, leading to early termination of translation at residue Gln2803 (p. Gln2803Ter), and a small deletion c. 4020_4031del, resulting in an in-frame deletion of three amino acid residues (p. Asp1343_Val1346del). Both variants retain a large part of the CHS/LYST protein, particularly p. Asp1343_Val1346del, which preserves critical functional BEACH and WD40 domains in the C terminal, potentially maintaining residual activity and alleviating patient symptoms. The timeline of SARS-CoV-2 infection and rapid symptom progression suggests that the viral infection may have trigger the accelerated phase development leading to a poor prognosis.
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Pressure-induced magnetic phase transitions are attracting interest as a means to detect superconducting behaviour at high pressures in diamond anvil cells, but determining the local magnetic properties of samples is a challenge due to the small volumes of sample chambers. Optically detected magnetic resonance of nitrogen vacancy centres in diamond has recently been used for the in situ detection of pressure-induced phase transitions. However, owing to their four orientation axes and temperature-dependent zero-field splitting, interpreting these optically detected magnetic resonance spectra remains challenging. Here we study the optical and spin properties of implanted silicon vacancy defects in 4H-silicon carbide that exhibit single-axis and temperature-independent zero-field splitting. Using this technique, we observe the magnetic phase transition of Nd2Fe14B at about 7 GPa and map the critical temperature-pressure phase diagram of the superconductor YBa2Cu3O6.6. These results highlight the potential of silicon vacancy-based quantum sensors for in situ magnetic detection at high pressures.
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Nicotianamine (NA) plays a crucial role in transporting metal ions, including iron (Fe), in plants; therefore, NICOTIANAMINE SYNTHASE (NAS) genes, which control NA synthesis, are tightly regulated at the transcriptional level. However, the transcriptional regulatory mechanisms of NAS genes require further investigations. In this study, we determined the role of bZIP44 in mediating plant response to Fe deficiency stress by conducting transformation experiments and assays. bZIP44 positively regulated the response of Arabidopsis to Fe deficiency stress by interacting with MYB10 and MYB72 to enhance their abilities to bind at NAS2 and NAS4 promoters, thereby increasing NAS2 and NAS4 transcriptional levels and promote NA synthesis. In summary, the transcription activities of bZIP44, MYB10, and MYB72 were induced in response to Fe deficiency stress, which enhanced the interaction between bZIP44 and MYB10 or MYB72 proteins, synergistically activated the transcriptional activity of NAS2 and NAS4, promoted NA synthesis, and improved Fe transport, thereby enhancing plant tolerance to Fe deficiency stress.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fatores de Transcrição de Zíper de Leucina Básica , Regulação da Expressão Gênica de Plantas , Ferro , Estresse Fisiológico , Alquil e Aril Transferases/metabolismo , Alquil e Aril Transferases/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Ácido Azetidinocarboxílico/análogos & derivados , Ácido Azetidinocarboxílico/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Ferro/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Ligação Proteica , Estresse Fisiológico/genéticaRESUMO
SARS-CoV-2 breakthrough infections in vaccinated individuals underscore the threat posed by continuous mutating variants, such as Omicron, to vaccine-induced immunity. This necessitates the search for broad-spectrum immunogens capable of countering infections from such variants. This study evaluates the immunogenicity relationship among SARS-CoV-2 variants, from D614G to XBB, through Guinea pig vaccination, covering D614G, Alpha, Beta, Gamma, Delta, BA.1, BA.2, BA.2.75, BA.2.75.2, BA.5, BF.7, BQ.1.1, and XBB, employing three immunization strategies: three-dose monovalent immunogens, three-dose bivalent immunogens, and a two-dose vaccination with D614G followed by a booster immunization with a variant strain immunogen. Three distinct immunogenicity clusters were identified: D614G, Alpha, Beta, Gamma, and Delta as cluster 1, BA.1, BA.2, and BA.2.75 as cluster 2, BA.2.75.2, BA.5, BF.7, BQ.1.1, and XBB as cluster 3. Broad-spectrum protection could be achieved through a combined immunization strategy using bivalent immunogens or D614G and XBB, or two initial D614G vaccinations followed by two XBB boosters. A comparison of neutralizing antibody levels induced by XBB boosting and equivalent dosing of D614G and XBB revealed that the XBB booster produced higher antibody levels. The study suggests that vaccine antigen selection should focus on the antigenic alterations among variants, eliminating the need for updating vaccine components for each variant.
Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Animais , Cobaias , SARS-CoV-2/genética , COVID-19/prevenção & controle , Anticorpos Neutralizantes , Análise por Conglomerados , Vacinas Combinadas , Anticorpos AntiviraisRESUMO
In this paper, we demonstrate a novel hybrid 3C-silicon carbide-lithium niobate (3C-SiC-LN) platform for passive and active integrated nanophotonic devices enabled through wafer bonding. These devices are fabricated by etching the SiC layer, with the hybrid optical mode power distributed between SiC and LN layers through a taper design. We present a racetrack resonator-based electro-optic (EO) phase shifter where the resonator is fabricated in SiC while using LN for EO-effect (r33≈ 27 pm/V). The proposed phase shifter demonstrates efficient resonance wavelength tuning with low voltage-length product (Vπ.Lπ ≈ 2.18â V cm) using the EO effect of LN. This hybrid SiC-LN platform would enable high-speed, low-power, and miniaturized photonic devices (e.g., modulators, switches, filters) operable over a broad range of wavelengths (visible to infrared) with applications in both classical and quantum nanophotonics.
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Background: Intravascular ultrasound (IVUS) has been utilized to determine acute stent mal-apposition (ASM) after percutaneous coronary intervention (PCI) in the left main coronary artery (LMCA). However, the clinical consequences of this finding remain uncertain. This research aimed to evaluate the clinical implications of ASM in the LMCA using IVUS. Methods: In this study, 408 patients who underwent successful drug-eluting stent (DES) implantation in the LMCA were evaluated. We analyzed the prevalence and characteristics of ASM and its correlation with clinical outcomes. ASM is characterized by stent struts that are not in immediate proximity to the intimal surface of the vessel wall after initial stent deployment. Results: The observed incidence of LMCA-ASM post-successful PCI was 26.2%, both per patient and per lesion. Lesions with LMCA-ASM had a longer stent diameter, larger stent areas, and larger lumen areas compared to those without LMCA-ASM (4.0 ± 0.5 vs. 3.7 ± 0.4 mm, p < 0.001; 9.8 ± 2.0 vs. 9.0 ± 1.6 mm 2 , p < 0.001; 12.3 ± 1.9 vs. 10.1 ± 2.1 mm 2 , p < 0.001, respectively). The mean external elastic membrane (EEM) area (odds ratio (OR): 1.418 [95% confidence interval (CI): 1.295-1.556]; p < 0.001) emerged as an independent predictor of LMCA-ASM. During the observation period, LMCA-ASM did not display any association with device-oriented clinical endpoints (DoCE), which included cardiac death, target vessel-induced myocardial infarction (MI), stent thrombosis, and target lesion revascularization (TLR). Moreover, the DoCE incidence exhibited no significant disparity between patients with or without ASM (13.1 vs. 6.0%, p = 0.103). Conclusions: While LMCA-ASM was a not uncommon finding post-PCI, it did not correlate with adverse cardiac events in the present study.
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Background: Calcified nodules (CN) have been linked to unfavorable clinical outcomes. However, there is a lack of systematic studies on non-culprit lesions with CN in patients with acute coronary syndromes (ACS). This study aims to investigate the frequency, distribution, predictors, and outcomes of CN in non-culprit lesions among ACS patients. Methods: We included 376 ACS patients who received successful stent placement in their culprit lesions. Intravascular ultrasound (IVUS) was performed to evaluate non-culprit lesions in left main arteries and all three coronary arteries (CA). CN was defined as accumulations of small nodular calcium deposits exhibiting a convex shape protruding into the lumen. Results: CNs was identified in 16.9% (121 of 712) per artery and 26.9% (101 of 376) per patient. They were predominantly located at the mid portion of the right coronary artery (26.3%) and the bifurcation site (59.9%). Patients with CN were older (63.57 ± 8.43 vs. 57.98 ± 7.15, p < 0.001) and had a higher prevalence of diabetes mellitus (55.4% vs. 42.2%, p = 0.022). However, there were no significant differences in baseline characteristics observed after propensity score matching (PSM). Multivariate analysis revealed that CN were independently associated with major adverse cardiovascular events (MACE) both before and after PSM (hazard ratio (HR): 0.341, 95% confidence interval (95% CI): 0.140-0.829, p = 0.018; HR: 0.275, 95% CI: 0.108-0.703, p = 0.007, respectively). During the observational period of 19.35 ± 10.59 months, the occurrence of MACE was significantly lower in patients with CN before and after PSM (5.9% vs. 16.7%, p = 0.046; 4.0% vs. 18.1%, p = 0.011; respectively). Conclusions: CN in non-culprit lesions with ACS patients was prevalent and caused fewer adverse clinical outcomes.
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Background: This study aimed to assess the clinical significance of generating a volumetric stent expansion index for tapering lesions through intravascular ultrasound (IVUS). Previous IVUS studies have used minimal stent area (MSA) to predict adverse outcomes. Methods: A total of 251 tapering lesions were treated in this study via IVUS guidance in 232 patients. Eight stent expansion indices were evaluated to determine the association of these indices with device-oriented clinical endpoints (DoCEs) after two-year follow-ups. These were the ILUMIEN III and IV standards, the ULTIMATE (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in "All-Comers" Coronary Lesions) standard, the IVUS-XPL (Impact of Intravascular Ultrasound Guidance on the Outcomes of Xience Prime Stents in Long Lesions) standard, the minimal volumetric expansion index (MVEI) using the Huo-Kassab or linear model, the MSA/vessel area at the MSA cross-section, the traditional stent expansion (MSA/mean proximal and distal reference lumen cross-sectional area), and MSA. Results: The MVEI was the only stent expansion index that correlated significantly with the two-year DoCEs (hazard ratio [HR], 1.91; 95% confidence interval [CI]: 1.16-3.96; p = 0.028). In the ROC analysis, the area under the curve for the MVEI was 0.71 (p = 0.002), with an optimal cut-off value of 62.2 for predicting the DoCEs. Conclusions: This is the first study to use IVUS for tapering lesions and demonstrate that the MVEI is an independent predictor of two-year DoCEs.
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Synergistic engineering of energy band alignment and interfacial electric field distribution is essential for photocatalyst design but is still challenging because of the limitation on refined regulation in the nanoscale. This study addresses the issue by employing surface modification and thermal-induced phase transformation in Bi2MoO6/BixOyIz hetero-nanofiber frameworks. The energy band alignment switches from a type-II interface to a Z-scheme contact with stronger redox potentials and inhibited electron traps, and the optimized built-in electric field distribution could be reached based on experimental and theoretical investigations. The engineered hetero-nanofibers exhibit outstanding visible-light-driven photocatalytic nitrogen reduction activity (605 µmol/g/h) and tetracycline hydrochloride removal rate (81.5% within 30 min), ranking them among the top-performing bismuth series materials. Furthermore, the photocatalysts show promise in activating advanced oxidants for efficient organic pollutant degradation. Moreover, the Bi2MoO6/Bi5O7I hetero-nanofibers possess good recycling stability owing to their three-dimensional network structure. This research offers valuable insights into heterojunction design for environmental remediation and industrial applications.