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1.
Cancers (Basel) ; 13(21)2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34771497

RESUMO

Immune checkpoint inhibitors can improve the prognosis of patients with advanced malignancy; however, only a small subset of advanced colorectal cancer patients in microsatellite-instability-high or mismatch-repair-deficient colorectal cancer can benefit from immunotherapy. Unfortunately, the mechanism behind this ineffectiveness is unclear. The tumor microenvironment plays a critical role in cancer immunity, and may contribute to the inhibition of immune checkpoint inhibitors and other novel immunotherapies in patients with advanced cancer. Herein, we demonstrate that the DNase I enzyme plays a pivotal role in the degradation of NETs, significantly dampening the resistance to anti-PD-1 blockade in a mouse colorectal cancer model by attenuating tumor growth. Remarkably, DNase I decreases tumor-associated neutrophils and the formation of MC38 tumor cell-induced neutrophil extracellular trap formation in vivo. Mechanistically, the inhibition of neutrophil extracellular traps with DNase I results in the reversal of anti-PD-1 blockade resistance through increasing CD8+ T cell infiltration and cytotoxicity. These findings signify a novel approach to targeting the tumor microenvironment using DNase I alone or in combination with immune checkpoint inhibitors.

2.
J Phys Chem Lett ; : 11503-11510, 2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34797083

RESUMO

Understanding proton transport in Ruddlesden-Popper (RP) oxides, as attractive electrode materials for protonic ceramic fuel cells, is challenging because of the complexity of intrinsic oxygen defects in first-series RP oxides (A2BO4). We investigated the processes of intrinsic oxygen defects in proton transportation, such as formation of defects, incorporation of dissociative water into the defective lattice, transfer of a proton along the oxygen sites, and electronic properties of the transition state (TS) in A2BO4. The coexistence of oxygen vacancies (VO) and interstitial oxygen (Oi), VO+Oi defect pair, presents advantageous hydration energies and lattice distortions efficiently accelerating proton transport in the lattice. Moreover, the inherent driving force for proton transport is related to the O 2p band level by O-H···O bond interactions in the TS. Our findings elucidate the fundamental mechanism of proton conduction affected by intrinsic oxygen defects, which will motivate the community to focus more on defect engineering to enhance performance.

3.
J Agric Food Chem ; 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34812623

RESUMO

A type III polyketide synthase (SfuPKS1) from the edible seaweed Sargassum fusiforme was molecularly cloned and biochemically characterized. The recombinant SfuPKS1 catalyzed the condensation of fatty acyl-CoA with two or three malonyl-CoA using lactone-type intramolecular cyclization to produce tri- and/or tetraketides. Moreover, it can also utilize phenylpropanoyl-CoA to synthesize phloroglucinol derivatives through Claisen-type cyclization, exhibiting broad substrate and catalysis specificity. Furthermore, the catalytic efficiency (kcat/KM) for acetyl-CoA was 11.8-fold higher than that for 4-coumaroyl-CoA. A pathway for the synthesis of naringenin involving SfuPKS1 was also constructed in Escherichia coli by recombinant means, resulting in 4.9 mg of naringenin per liter.

4.
J Am Chem Soc ; 143(40): 16512-16518, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34601870

RESUMO

Heterojunction nanostructures usually exhibit enhanced properties in compariosn with their building blocks and are promising catalyst candidates due to their combined surface and unique interface. Here, for the first time we realized the oriented growth of ultrasmall metal nanoparticles (NPs) on metal-organic framework nanosheets (MOF NSs) by precisely regulating the reduction kinetics of metal ions with solvents. In particular, a rapid reduction of metal ions leads to the random distribution of metal NPs on the surface of MOF NSs, while a slow reduction of metal ions results in the oriented growth of NPs on the edge of MOF NSs. Impressively, the strong synergy between Pt NPs and MOF NSs significantly enhances the hydrogen evolution reaction (HER) performance, and the optimal catalyst displays HER activities superior to those of a composite with a random growth of Pt NPs and commercial Pt/C under both acidic and alkaline conditions. Moreover, the versatility of such oriented growth has been extended to other metal NPs, such as Pd, Ag, and Au. We believe this work will promote research interest in material design for many potential applications.

5.
Adv Mater ; : e2105308, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34610648

RESUMO

To improve the electroactivity and stability of electrocatalysts, various modulation strategies have been applied in nanocatalysts. Among different methods, heteroatom doping has been considered as an effective method, which modifies the local bonding environments and the electronic structures. Meanwhile, the design of novel two-dimensional (2D) nanostructures also offers new opportunities for achieving efficient electrocatalysts. In this work, Mn-doped ultrathin Ru nanosheet branches (RuMn NSBs), a newly reported 2D nanostructure, is synthesized. With the ultrathin and naturally abundant edges, the RuMn NSBs have exhibited bifunctionalities of hydrogen evolution reaction and oxygen evolution reaction with high electroactivity and durability in different electrolytes. Experimental characterizations have revealed that RuO bonds are shortened due to Mn doping, which is the key factor that leads to improved electrochemical performances. Density functional theory (DFT) calculations have confirmed that the introduction of Mn enables flexible modulations on the valence states of Ru sites. The inversed redox state evolutions of Ru and Mn sites not only improve the electroactivity for the water splitting but also the long-term stability due to the pinning effect of Ru sites. This work has provided important inspirations for the design of future advanced Ru-based electrocatalysts with high performances and durability.

6.
Inorg Chem ; 60(21): 16308-16315, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34658238

RESUMO

A 4H-type BaMnO3 single crystal was prepared by combining the floating zone method with high-pressure treatment at 5 GPa and 1023 K. The crystal crystallizes to a hexagonal structure with space group P63/mmc and lattice parameters a = 5.63723(5) Å and c = 9.22355(8) Å. In this structure, face-sharing MnO6 octahedral dimers connect with each other by corner O atoms along the c-axis direction, forming an -A-B-A-C-type 4H arrangement. A long-range antiferromagnetic (AFM) phase transition is found to occur at TN ≈ 263 K. When the synthesis pressure increases to 20 GPa, a new polymorphic phase is obtained. This higher-pressure phase still possesses the hexagonal P63/mmc symmetry, but the lattice parameters change to be a = 5.61349(2) Å and c = 13.66690(9) Å with a unit cell volume reduction of 2.05%. In this new phase, the c-axis MnO6 dimers are separated by MnO6 octahedral layers in the ab plane, forming an -A-B-C-A-C-B-type 6H structure. The 6H phase exhibits two long-range AFM orderings at TN1 ≈ 220 K and TN2 ≈ 25 K, respectively. The different magnetic properties are discussed on the basis of the detailed structural constitutions of 4H- and 6H-BaMnO3.

7.
Artigo em Inglês | MEDLINE | ID: mdl-34469313

RESUMO

Recently, referring image localization and segmentation has aroused widespread interest. However, the existing methods lack a clear description of the interdependence between language and vision. To this end, we present a bidirectional relationship inferring network (BRINet) to effectively address the challenging tasks. Specifically, we first employ a vision-guided linguistic attention module to perceive the keywords corresponding to each image region. Then, language-guided visual attention adopts the learned adaptive language to guide the update of the visual features. Together, they form a bidirectional cross-modal attention module (BCAM) to achieve the mutual guidance between language and vision. They can help the network align the cross-modal features better. Based on the vanilla language-guided visual attention, we further design an asymmetric language-guided visual attention, which significantly reduces the computational cost by modeling the relationship between each pixel and each pooled subregion. In addition, a segmentation-guided bottom-up augmentation module (SBAM) is utilized to selectively combine multilevel information flow for object localization. Experiments show that our method outperforms other state-of-the-art methods on three referring image localization datasets and four referring image segmentation datasets.

8.
Medicine (Baltimore) ; 100(33): e26944, 2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34414955

RESUMO

BACKGROUND: To explore the diagnostic value of computed tomography (CT) imaging for duodenal lipoma and the potential clinical significance of the findings. METHODS: Clinicopathological and CT data from 57 patients, who were diagnosed with duodenal lipoma at the first affiliated Hospital of Zhengzhou University (Zhengzhou, China) between June 2014 and March 2019, were retrospectively reviewed. Data collected included location and size of the tumor, morphological manifestations (shape, density, boundary), concomitant diseases, pathology and gastroscopy results, and follow-up. Follow-up was performed via telephone, and surgical patients were followed-up for recurrence, metastasis and tumor size, and morphological changes. The follow-up period was up to January 2019. RESULTS: Of the 57 patients with duodenal lipoma, contrast-enhanced scanning was performed in 7 cases. The tumor was located in the descending duodenum in 33 cases, the ascending in 4 cases, the horizontal in 16 cases, and the bulb in 4 cases. Mean tumor size was 13.0 ±â€Š5.8 mm. CT morphological features of the tumor were as follows: tumor shape, round, quasi-round, or oval (n = 42); long strip (n = 3); nodular (n = 2); triangular (n = 1); and irregular lobulated (n = 9). Among the 57 patients, tumor density was homogeneous in 52 cases, inhomogeneous in 4 cases, and nodular with calcification in 1 case. The tumor boundary was classified as clear and with no capsule. Diseases concomitant with the tumor were as follows: gastritis (n = 23), gastric adenocarcinoma (n = 1), and gastric lymphoma (n = 1). Esophageal disease was found in 16 cases, including reflux esophagitis (n = 12) and esophageal cancer (n = 4). There were 13 cases of gallbladder and biliary disease, including cholecystolithiasis and cholecystitis (n = 9), common bile duct disease (n = 2), colorectal cancer (n = 4), lung cancer (n = 2), duodenal carcinoma with obstruction (n = 1), and ureteral space narrowing (n = 1). CONCLUSION: CT was an effective, non-invasive method for diagnosis of duodenal lipoma. CT imaging could clearly discern location, size, shape, and nature of duodenal lipomas. Duodenal lipoma can be associated with digestive tract inflammatory diseases and tumors in different locations, and its diagnosis is potentially valuable for their prevention and treatment.


Assuntos
Neoplasias Duodenais/diagnóstico por imagem , Lipoma/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Neoplasias Duodenais/diagnóstico , Neoplasias Duodenais/patologia , Duodeno/diagnóstico por imagem , Duodeno/patologia , Feminino , Humanos , Lipoma/diagnóstico , Lipoma/patologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Tomografia Computadorizada por Raios X
9.
Adv Mater ; 33(41): e2103392, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34436805

RESUMO

Corner-sharing oxides usually suffer from structural reconstruction during the bottleneck oxygen-evolution reaction (OER) in water electrolysis. Therefore, introducing dynamically stable active sites in an alternative structure is urgent but challenging. Here, 1D 5H-polytype Ba5 Bi0.25 Co3.75 FeO14- δ oxide with face-sharing motifs is identified as a highly active and stable candidate for alkaline OER. Benefiting from the stable face-sharing motifs with three couples of combined bonds, Ba5 Bi0.25 Co3.75 FeO14- δ can maintain its local structures even under high OER potentials as evidenced by fast operando spectroscopy, contributing to a negligible performance degradation over 110 h. Besides, the higher Co valence and smaller orbital bandgap in Ba5 Bi0.25 Co3.75 FeO14- δ endow it with a much better electron transport ability than its corner-sharing counterpart, leading to a distinctly reduced overpotential of 308 mV at 10 mA cm-2 in 0.1 m KOH. Further mechanism studies show that the short distance between lattice-oxygen sites in face-sharing Ba5 Bi0.25 Co3.75 FeO14- δ can accelerate the deprotonation step (*OOH + OH-  = *OO + H2 O + e- ) via a steric inductive effect to promote lattice-oxygen participation. In this work, not only is a new 1D face-sharing oxide with impressive OER performance discovered, but also a rational design of dynamic stable and active sites for sustainable energy systems is inaugurated.

10.
J Hepatol ; 75(6): 1271-1283, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34363921

RESUMO

BACKGROUND & AIMS: Regulatory T-cells (Tregs) impair cancer immunosurveillance by creating an immunosuppressive environment that fosters tumor cell survival. Our previous findings demonstrated that neutrophil extracellular traps (NETs), which are involved both in innate and adaptive immunity, are abundant in livers affected by non-alcoholic steatohepatitis (NASH). However, how NETs interact with Tregs in the development of NASH-associated hepatocellular carcinoma (NASH-HCC) is not known. METHODS: A choline-deficient, high-fat diet+diethylnitrosamine mouse model and the stelic animal model were utilized for NASH-HCC and a western diet mouse model was used for NASH development. Treg depletion was achieved using FoxP3-DTR mice. RNA sequencing was used to explore the mechanism by which NETs could regulate Treg differentiation. Bioenergetic analyses of naïve CD4+ T-cells were assessed by Seahorse. RESULTS: Although the absolute number of CD4+ T-cells is lower in NASH livers, the Treg subpopulation is selectively increased. Depleting Tregs dramatically inhibits HCC initiation and progression in NASH. There is a positive correlation between increased NET and hepatic Treg levels. RNA sequencing data reveals that NETs impact gene expression profiles in naïve CD4+ T-cells, with the most differentially expressed genes being those involved in mitochondrial oxidative phosphorylation. By facilitating mitochondrial respiration, NETs can promote Treg differentiation. Metabolic reprogramming of naïve CD4+ T-cells by NETs requires toll-like receptor 4. Blockade of NETs in vivo using Pad4-/- mice or DNase I treatment reduces the activity of Tregs. CONCLUSIONS: Tregs can suppress immunosurveillance in the premalignant stages of NASH. NETs facilitate the crosstalk between innate and adaptive immunity in NASH by promoting Treg activity through metabolic reprogramming. Therapies targeting NETs and Treg interactions could offer a potential strategy for preventing HCC in patients with NASH. LAY SUMMARY: Regulatory T-cells (Tregs) can promote tumor development by suppressing cancer immunosurveillance, but their role in carcinogenesis during non-alcoholic steatohepatitis (NASH) progression is unknown. Herein, we discovered that selectively increased intrahepatic Tregs can promote an immunosuppressive environment in NASH livers. Neutrophil extracellular traps (NETs) link innate and adaptive immunity by promoting Treg differentiation via metabolic reprogramming of naïve CD4+ T-cells. This mechanism could be targeted to prevent liver cancer in patients with NASH.

11.
Sci Rep ; 11(1): 14256, 2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34244574

RESUMO

Kondo effect is an interesting phenomenon in quantum many-body physics. Niobium (Nb) is a conventional superconductor important for many superconducting device applications. It was long thought that the Kondo effect cannot be observed in Nb because the magnetic moment of a magnetic impurity, e.g. iron (Fe), would have been quenched in Nb. Here we report an observation of the Kondo effect in a Nb thin film structure. We found that by co-annealing Nb films with Fe in Argon gas at above 400 [Formula: see text]C for an hour, one can induce a Kondo effect in Nb. The Kondo effect is more pronounced at higher annealing temperature. The temperature dependence of the resistance suggests existence of remnant superconductivity at low temperatures even though the system never becomes superconducting. We find that the Hamann theory for the Kondo resistivity gives a satisfactory fitting to the result. The Hamann analysis gives a Kondo temperature for this Nb-Fe system at [Formula: see text] 16 K, well above the superconducting transition onset temperature 9 K of the starting Nb film, suggesting that the screening of the impurity spins is effective to allow Cooper pairs to form at low temperatures. We suggest that the mechanism by which the Fe impurities retain partially their magnetic moment is that they are located at the grain boundaries, not fully dissolved into the bcc lattice of Nb.

12.
Nano Lett ; 21(15): 6625-6632, 2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34319751

RESUMO

Developing a large-scale method to produce platinum (Pt)-based electrocatalysts for the oxygen reduction reaction (ORR) is highly desirable to propel the commercialization of the membrane electrode assembly (MEA). Here, we successfully report the large-scale production of surfactant-free ruthenium-doped Pt-cobalt octahedra grown on carbon (Ru-Pt3Co/C), which display a much higher ORR activity and stability and MEA stability than Pt3Co/C and Pt/C. Significantly, the in-situ X-ray absorption fine structure result reveals that Ru can drive the reduced Pt atoms to reverse to their initial state after the ORR by transferring a redundant electron from Pt to Ru, preventing the over-reduction of Pt active sites and boosting the chemical stability. Theory investigations further confirm that the doped Ru can accelerate the breach and desorption of oxygen intermediates, making it active and durable for the ORR. The present work sheds light on the exploration of a large-scale strategy for producing advanced Pt-based nanocatalysts, which may offer significant advantages for practical fuel cell applications in the future.

13.
Small ; 17(29): e2101573, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34137160

RESUMO

Single-phase perovskite oxides that contain nonprecious metals have long been pursued as candidates for catalyzing the oxygen evolution reaction, but their catalytic activity cannot meet the requirements for practical electrochemical energy conversion technologies. Here a cation deficiency-promoted phase separation strategy to design perovskite-based composites with significantly enhanced water oxidation kinetics compared to single-phase counterparts is reported. These composites, self-assembled from perovskite precursors, comprise strongly interacting perovskite and related phases, whose structure, composition, and concentration can be accurately controlled by tailoring the stoichiometry of the precursors. The composite catalyst with optimized phase composition and concentration outperforms known perovskite oxide systems and state-of-the-art catalysts by 1-3 orders of magnitude. It is further demonstrated that the strong interfacial interaction of the composite catalysts plays a key role in promoting oxygen ionic transport to boost the lattice-oxygen participated water oxidation. These results suggest a simple and viable approach to developing high-performance, perovskite-based composite catalysts for electrochemical energy conversion.

14.
Adv Biol (Weinh) ; 5(8): e2000202, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34117721

RESUMO

Endometrial injury and intrauterine adhesions are increasingly reported in recent years; however, treatment options remain limited. Intravenous injection of mesenchymal stem cells (MSCs) for endometrium regeneration has limited effectiveness as the retention rate of transplanted cells is low. Hydrogel-based tissue-engineered solutions, such as MSC-seeded bioscaffolds, are reported to increase retention rates; however, a less invasive alternative is still desirable. 560-µm homogeneous Matrigel microspheres are fabricated, loading them with about 1500 MSCs and injecting them into the injured endometria of rats' uteri. This minimally invasive procedure is proved to significantly increase endometrium thickness by over onefold after 21 d (p < 0.0001) and fertility rates from 25% to 75% in impaired and repaired uteri (p < 0.001), respectively. This study provides a minimally invasive alternative to endometrium repair with the promise to establish a broad-spectrum technique for MSC transplantation.


Assuntos
Células-Tronco Mesenquimais , Animais , Colágeno , Combinação de Medicamentos , Endométrio , Feminino , Laminina , Microesferas , Proteoglicanas , Ratos , Regeneração
15.
Nat Commun ; 12(1): 3136, 2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34035291

RESUMO

Structural degradation in manganese oxides leads to unstable electrocatalytic activity during long-term cycles. Herein, we overcome this obstacle by using proton exchange on well-defined layered Li2MnO3 with an O3-type structure to construct protonated Li2-xHxMnO3-n with a P3-type structure. The protonated catalyst exhibits high oxygen reduction reaction activity and excellent stability compared to previously reported cost-effective Mn-based oxides. Configuration interaction and density functional theory calculations indicate that Li2-xHxMnO3-n has fewer unstable O 2p holes with a Mn3.7+ valence state and a reduced interlayer distance, originating from the replacement of Li by H. The former is responsible for the structural stability, while the latter is responsible for the high transport property favorable for boosting activity. The optimization of both charge states to reduce unstable O 2p holes and crystalline structure to reduce the reaction pathway is an effective strategy for the rational design of electrocatalysts, with a likely extension to a broad variety of layered alkali-containing metal oxides.

16.
Inorg Chem ; 60(9): 6298-6305, 2021 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-33848160

RESUMO

B-site Os-doped quadruple perovskite oxides LaCu3Fe4-xOsxO12 (x = 1 and 2) were prepared under high-pressure and high-temperature conditions. Although parent compound LaCu3Fe4O12 experiences Cu-Fe intermetallic charge transfer that changes the Cu3+/Fe3+ charge combination to Cu2+/Fe3.75+ at 393 K, in the Os-doped samples, the Cu and Fe charge states are found to be constant 2+ and 3+, respectively, indicating the complete suppression of charge transfer. Correspondingly, Os6+ and mixed Os4.5+ valence states are determined by X-ray absorption spectroscopy for x = 1 and x = 2 compositions, respectively. The x = 1 sample crystallizes in an Fe/Os disordered structure with the Im3̅ space group. It experiences a spin-glass transition around 480 K. With further Os substitution up to x = 2, the crystal symmetry changes to Pn3̅, where Fe and Os are orderly distributed in a rocksalt-type fashion at the B site. Moreover, this composition shows a long-range Cu2+(↑)Fe3+(↑)Os4.5+(↓) ferrimagnetic ordering near 520 K. This work provides a rare example for 5d substitution-suppressed intermetallic charge transfer as well as induced structural and magnetic phase transitions with high spin ordering temperature.

17.
mBio ; 12(2)2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33879582

RESUMO

Base editing is a powerful genome editing approach that enables single-nucleotide changes without double-stranded DNA breaks (DSBs). However, off-target effects as well as other undesired editings at on-target sites remain obstacles for its application. Here, we report that bubble hairpin single guide RNAs (BH-sgRNAs), which contain a hairpin structure with a bubble region on the 5' end of the guide sequence, can be efficiently applied to both cytosine base editor (CBE) and adenine base editor (ABE) and significantly decrease off-target editing without sacrificing on-target editing efficiency. Meanwhile, such a design also improves the purity of C-to-T conversions induced by base editor 3 (BE3) at on-target sites. Our results present a distinctive and effective strategy to improve the specificity of base editing.IMPORTANCE Base editors are DSB-free genome editing tools and have been widely used in diverse living systems. However, it is reported that these tools can cause substantial off-target editings. To meet this challenge, we developed a new approach to improve the specificity of base editors by using hairpin sgRNAs with a bubble. Furthermore, our sgRNA design also dramatically reduced indels and unwanted base substitutions at on-target sites. We believe that the BH-sgRNA design is a significant improvement over existing sgRNAs of base editors, and our design promises to be adaptable to various base editors. We expect that it will make contributions to improving the safety of gene therapy.


Assuntos
Edição de Genes/métodos , RNA Guia/genética , Adenina , Sistemas CRISPR-Cas , Citosina , Células HEK293 , Humanos , Mutação
18.
Angew Chem Int Ed Engl ; 60(20): 11190-11195, 2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-33694245

RESUMO

Two-dimensional (2D) metal-organic framework nanosheets (MOF NSs) play a vital role in catalysis, but the most preparation is ultrasonication or solvothermal. Herein, a liquid-liquid interfacial synthesis method has been developed for the efficient fabrication of a series of 2D Ni MOF NSs. The active sites could be modulated by readily tuning the ratios of metal precursors and organic linkers (RM/L ). The Ni MOF NSs display highly RM/L dependent activities towards 2e oxygen reduction reaction (ORR) to hydrogen peroxide (H2 O2 ), where the Ni MOF NSs with the RM/L of 6 exhibit the optimal near-zero overpotential, ca. 98 % H2 O2 selectivity and production rate of ca. 80 mmol gcat -1 h-1 in 0.1 M KOH. As evidenced by X-ray absorption fine structure spectroscopy, the coordination environment of active sites changed from saturation to unsaturation, and the partially unsaturated metal atoms are crucial to create optimal sites for enhancing the electrocatalysis.

19.
Nat Commun ; 12(1): 1917, 2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33772004

RESUMO

PbMO3 (M = 3d transition metals) family shows systematic variations in charge distribution and intriguing physical properties due to its delicate energy balance between Pb 6s and transition metal 3d orbitals. However, the detailed structure and physical properties of PbFeO3 remain unclear. Herein, we reveal that PbFeO3 crystallizes into an unusual 2ap × 6ap × 2ap orthorhombic perovskite super unit cell with space group Cmcm. The distinctive crystal construction and valence distribution of Pb2+0.5Pb4+0.5FeO3 lead to a long range charge ordering of the -A-B-B- type of the layers with two different oxidation states of Pb (Pb2+ and Pb4+) in them. A weak ferromagnetic transition with canted antiferromagnetic spins along the a-axis is found to occur at 600 K. In addition, decreasing the temperature causes a spin reorientation transition towards a collinear antiferromagnetic structure with spin moments along the b-axis near 418 K. Our theoretical investigations reveal that the peculiar charge ordering of Pb generates two Fe3+ magnetic sublattices with competing anisotropic energies, giving rise to the spin reorientation at such a high critical temperature.

20.
Cancer Res ; 81(9): 2373-2385, 2021 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-33687949

RESUMO

Surgical removal of malignant tumors is a mainstay in controlling most solid cancers. However, surgical insult also increases the risk of tumor recurrence and metastasis. Tissue trauma activates the innate immune system locally and systemically, mounting an inflammatory response. Platelets and neutrophils are two crucial players in the early innate immune response that heals tissues, but their actions may also contribute to cancer cell dissemination and distant metastasis. Here we report that surgical stress-activated platelets enhance the formation of platelet-tumor cell aggregates, facilitating their entrapment by neutrophil extracellular traps (NET) and subsequent distant metastasis. A murine hepatic ischemia/reperfusion (I/R) injury model of localized surgical stress showed that I/R promotes capturing of aggregated circulating tumor cells (CTC) by NETs and eventual metastasis to the lungs, which are abrogated when platelets are depleted. Hepatic I/R also increased deposition of NETs within the lung microvasculature, but depletion of platelets had no effect. TLR4 was essential for platelet activation and platelet-tumor cell aggregate formation in an ERK5-GPIIb/IIIa integrin-dependent manner. Such aggregation facilitated NET-mediated capture of CTCs in vitro under static and dynamic conditions. Blocking platelet activation or knocking out TLR4 protected mice from hepatic I/R-induced metastasis with no CTC entrapment by NETs. These results uncover a novel mechanism where platelets and neutrophils contribute to metastasis in the setting of acute inflammation. Targeted disruption of the interaction between platelets and NETs holds therapeutic promise to prevent postoperative distant metastasis. SIGNIFICANCE: Targeting platelet activation via TLR4/ERK5/integrin GPIIb/IIIa signaling shows potential for preventing NET-driven distant metastasis in patients post-resection.


Assuntos
Plaquetas/imunologia , Armadilhas Extracelulares/metabolismo , Fígado/lesões , Neoplasias Pulmonares/secundário , Proteína Quinase 7 Ativada por Mitógeno/metabolismo , Células Neoplásicas Circulantes/metabolismo , Neutrófilos/imunologia , Traumatismo por Reperfusão/metabolismo , Receptor 4 Toll-Like/deficiência , Animais , Plaquetas/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Neoplasias Pulmonares/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Recidiva Local de Neoplasia , Neutrófilos/metabolismo , Transdução de Sinais/genética , Receptor 4 Toll-Like/genética
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