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1.
Nature ; 599(7886): 576-581, 2021 11.
Artículo en Inglés | MEDLINE | ID: mdl-34819684

RESUMEN

Efficient magnetic control of electronic conduction is at the heart of spintronic functionality for memory and logic applications1,2. Magnets with topological band crossings serve as a good material platform for such control, because their topological band degeneracy can be readily tuned by spin configurations, dramatically modulating electronic conduction3-10. Here we propose that the topological nodal-line degeneracy of spin-polarized bands in magnetic semiconductors induces an extremely large angular response of magnetotransport. Taking a layered ferrimagnet, Mn3Si2Te6, and its derived compounds as a model system, we show that the topological band degeneracy, driven by chiral molecular orbital states, is lifted depending on spin orientation, which leads to a metal-insulator transition in the same ferrimagnetic phase. The resulting variation of angular magnetoresistance with rotating magnetization exceeds a trillion per cent per radian, which we call colossal angular magnetoresistance. Our findings demonstrate that magnetic nodal-line semiconductors are a promising platform for realizing extremely sensitive spin- and orbital-dependent functionalities.

2.
Neuroimage ; 288: 120533, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38340880

RESUMEN

AIM: Brain volume is influenced by several factors that can change throughout the day. In addition, most of these factors are influenced by sleep quality. This study investigated diurnal variation in brain volume and its relation to overnight sleep quality. METHODS: We enrolled 1,003 healthy Koreans without any psychiatric disorders aged 60 years or older. We assessed sleep quality and average wake time using the Pittsburgh Sleep Quality Index, and divided sleep quality into good, moderate, and poor groups. We estimated the whole and regional brain volumes from three-dimensional T1-weighted brain MRI scans. We divided the interval between average wake-up time and MRI acquisition time (INT) into tertile groups: short (INT1), medium (INT2), and long (INT3). RESULTS: Whole and regional brain volumes showed no significance with respect to INT. However, the `interaction between INT and sleep quality showed significance for whole brain, cerebral gray matter, and cerebrospinal fluid volumes (p < .05). The INT2 group showed significantly lower volumes of whole brain, whole gray matter, cerebral gray matter, cortical gray matter, subcortical gray matter, and cerebrospinal fluid than the INT1 and INT3 groups only in the individuals with good sleep quality. CONCLUSION: Human brain volume changes significantly within a day associated with overnight sleep in the individuals with good sleep quality.


Asunto(s)
Encéfalo , Calidad del Sueño , Humanos , Anciano , Estudios Transversales , Estudios Retrospectivos , Encéfalo/diagnóstico por imagen , Sustancia Gris/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos
3.
Artículo en Inglés | MEDLINE | ID: mdl-38656473

RESUMEN

A Gram-stain-negative, aerobic, oxidase-positive, weakly catalase-positive, motile by means of a single polar flagellum, rod-shaped bacterium designated as strain S2-9T was isolated from sediment sampled in Wiyang pond, Republic of Korea. Growth of this strain was observed at 10-40 °C (optimum, 35 °C) and pH 5.5-9.5 (optimum, pH 7.0-8.0) and in the presence of 0-0.5 % NaCl in Reasoner's 2A broth. The major fatty acids (>10 %) of strain S2-9T were C16 : 0 and summed feature 3 (comprising a mixture of C16 : 1 ω7c and/or C16 : 1 ω6c). Ubiquinone-8 was detected as the respiratory quinone. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Strain S2-9T showed the highest 16S rRNA gene sequence similarity to Paucibacter oligotrophus CHU3T (98.7 %), followed by 'Paucibacter aquatile' CR182 (98.4 %), all type strains of Pelomonas species (98.1-98.3 %), Mitsuaria chitosanitabida NBRC 102408T (97.9 %), Kinneretia asaccharophila KIN192T (97.8 %), Mitsuaria chitinivorans HWN-4T (97.4 %), and Paucibacter toxinivorans 2C20T (97.4 %). Phylogenetic trees based on the 16S rRNA gene and whole-genome sequences showed that strain S2-9T formed a tight phylogenetic lineage with Paucibacter species (CHU3T, CR182, and 2C20T). Average nucleotide identity and digital DNA-DNA hybridization values between strain S2-9T and Paucibacter strains were 76.6-79.3% and 19.5-21.5 %, respectively. The genomic DNA G+C content of strain S2-9T was 68.3 mol%. Notably, genes responsible for both sulphur oxidation and reduction and denitrification were found in the genome of strain S2-9T, suggesting that strain S2-9T is involved in the nitrogen and sulphur cycles in pond ecosystems. Based on the polyphasic taxonomic results, strain S2-9T represents a novel species of the genus Paucibacter, for which the name Paucibacter sediminis sp. nov. is proposed. The type strain is S2-9T (= KACC 22267T= JCM 34541T).


Asunto(s)
Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano , Ácidos Grasos , Sedimentos Geológicos , Filogenia , Estanques , ARN Ribosómico 16S , Análisis de Secuencia de ADN , Ubiquinona , Ácidos Grasos/análisis , ARN Ribosómico 16S/genética , Sedimentos Geológicos/microbiología , Estanques/microbiología , ADN Bacteriano/genética , República de Corea , Hibridación de Ácido Nucleico
4.
Artículo en Inglés | MEDLINE | ID: mdl-39271434

RESUMEN

OBJECTIVES: This study evaluated the performances of the age, creatinine, and ejection fraction (ACEF) I and II scores and compare them with that of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II score in patients who underwent isolated off-pump coronary artery bypass grafting (OPCABG). Additionally, this study was designed to externally validate the performance of the updated ACEF II score. DESIGN: Retrospective observational study. PARTICIPANTS: A total of 936 patients who underwent OPCABG between January 1, 2013, and December 31, 2022, at a tertiary teaching center were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Predicted operative mortality was calculated using a risk score model. The predictive performance of each score was evaluated using receiver operating characteristic curves and calibration plots. The ACEF II score demonstrated the highest C-statistic (area under the curve = 0.831, 95% confidence interval: 0.691-0.971), while the C-statistics for ACEF I, updated ACEF II, and EuroSCORE II were 0.793 (0.645-0.940), 0.698 (0.524-0.872), and 0.780 (0.606-0.954), respectively. The ACEF II score exhibited significantly better discriminative performance than the updated ACEF II score (p = 0.010); however, no significant differences were observed compared with the ACEF I and EuroSCORE II scores (p = 0.118 and 0.354, respectively). CONCLUSIONS: ACEF I and II scores are reliable risk stratification models with performances comparable to the EuroSCORE II score in patients undergoing isolated OPCABG. However, the updated ACEF II score failed to demonstrate improved performance.

5.
Proc Natl Acad Sci U S A ; 118(47)2021 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-34789576

RESUMEN

Complex electronic phases in strongly correlated electron systems are manifested by broken symmetries in the low-energy electronic states. Some mysterious phases, however, exhibit intriguing energy gap opening without an apparent signature of symmetry breaking (e.g., high-TC cuprates and heavy fermion superconductors). Here, we report an unconventional gap opening in a heterostructured, iron-based superconductor Sr2VO3FeAs across a phase transition at T 0 ∼150 K. Using angle-resolved photoemission spectroscopy, we identify that a fully isotropic gap opens selectively on one of the Fermi surfaces with finite warping along the interlayer direction. This band selectivity is incompatible with conventional gap opening mechanisms associated with symmetry breaking. These findings, together with the unusual field-dependent magnetoresistance, suggest that the Kondo-type proximity coupling of itinerant Fe electrons to localized V spin plays a role in stabilizing the exotic phase, which may serve as a distinct precursor state for unconventional superconductivity.

6.
Arthroscopy ; 40(8): 2174-2183, 2024 08.
Artículo en Inglés | MEDLINE | ID: mdl-38311267

RESUMEN

PURPOSE: To determine the effects of topical tranexamic acid (TXA) administration on tendon adhesions, shoulder range of motion (ROM), and tendon healing in an acute rotator cuff repair rat model. METHODS: A total of 20 Sprague Dawley rats were used. Tendon adhesion, ROM, and biomechanical and histological analysis of tendon-bone healing was conducted at 3 and 6 weeks after surgery. The rats underwent rotator cuff repair surgery on both shoulders and were administered TXA via subacromial injections. The tendon adhesion was evaluated macroscopically and histologically. Biomechanical tendon healing was measured using a universal testing machine, and histological analysis was quantified by H&E, Masson's trichrome, and picrosirius red staining. RESULTS: At 3 weeks after surgery, the adhesion score was significantly lower in the TXA group (2.10 ± 0.32) than in the control group (2.70 ± 0.48) (P = .005), but there was no significant difference between the 2 groups at 6 weeks. Regarding ROM, compared with the control group, the TXA group showed significantly higher external rotation (36.35° ± 4.52° vs 28.42° ± 4.66°, P < .001) and internal rotation (45.35° ± 9.36° vs 38.94° ± 5.23°, P = .013) 3 weeks after surgery. However, at 6 weeks, there were no significant differences in external and internal rotation between the 2 groups. In the biomechanical analysis, no significant differences in gross examination (3 weeks, P = .175, 6 weeks, P = .295), load to failure (3 weeks, P = .117, 6 weeks, P = .295), or ultimate stress (3 weeks, P = .602, 6 weeks, P = .917) were noted between the 2 groups 3 and 6 weeks after surgery. In the histological analysis of tendon healing, no significant differences in the total score (3 weeks, P = .323, 6 weeks, P = .572) were found between the 2 groups 3 and 6 weeks after surgery. CONCLUSIONS: Topical TXA administration showed a beneficial effect in reducing tendon adhesions and improving ROM 3 weeks postoperatively and had no effect at 6 weeks. This suggests that additional intervention with TXA may be useful in achieving long-term improvement in shoulder stiffness. Additionally, TXA may increase tissue ground substance accumulation in the late postoperative period but does not adversely affect tendon-bone interface healing. CLINICAL RELEVANCE: The use of TXA after rotator cuff repair has no effect on tendon-bone interface healing in clinical practice and can improve shoulder stiffness in the early postoperative period. Additional research on the long-term effects is needed.


Asunto(s)
Antifibrinolíticos , Modelos Animales de Enfermedad , Rango del Movimiento Articular , Ratas Sprague-Dawley , Lesiones del Manguito de los Rotadores , Ácido Tranexámico , Cicatrización de Heridas , Animales , Ácido Tranexámico/uso terapéutico , Ácido Tranexámico/administración & dosificación , Ácido Tranexámico/farmacología , Adherencias Tisulares/prevención & control , Adherencias Tisulares/etiología , Lesiones del Manguito de los Rotadores/cirugía , Lesiones del Manguito de los Rotadores/tratamiento farmacológico , Cicatrización de Heridas/efectos de los fármacos , Ratas , Antifibrinolíticos/uso terapéutico , Antifibrinolíticos/administración & dosificación , Antifibrinolíticos/farmacología , Rango del Movimiento Articular/efectos de los fármacos , Manguito de los Rotadores/cirugía , Masculino , Fenómenos Biomecánicos , Administración Tópica
7.
J Korean Med Sci ; 39(36): e246, 2024 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-39315441

RESUMEN

BACKGROUND: A decline in masticatory function may indicate brain dysfunction related to dementia, but the relationship between masticatory function and dementia risk remains unclear. This study aimed to investigate whether masticatory function is associated with the risk of cognitive decline and dementia. METHODS: Data were obtained from the nationwide prospective cohort study of randomly sampled community-dwelling Koreans aged ≥ 60 years. The 5,064 non-demented participants, whose number of chewing cycles per bite was assessed by clinical interview, were followed for 8 years with biennial assessments of cognitive performance and clinical diagnoses of all-cause dementia and Alzheimer's disease (AD). Structural brain magnetic resonance imaging was collected from a subset of cohort participants and their spouses for imaging analyses. RESULTS: Males who chewed ≥ 30 cycles/bite had faster decline in global cognition and memory function and were at higher risk for incident all-cause dementia (hazard ratio [HR], 2.91; 95% confidence interval [CI], 1.18-7.18) and AD (HR, 3.22; 95% CI, 1.14-9.11) compared to males with less than 10 cycles/bite. Additionally, increased chewing cycles in males were associated with reduced brain volume, particularly in regions involved in compensatory cognitive control of mastication. There was no significant association between chewing cycles and the risk of dementia or brain volume in females. CONCLUSION: Older men who frequently chew their meals could be considered a notable population at risk for dementia who should be carefully assessed for their cognitive trajectories.


Asunto(s)
Enfermedad de Alzheimer , Encéfalo , Demencia , Imagen por Resonancia Magnética , Masticación , Humanos , Masculino , Femenino , Anciano , Estudios Prospectivos , Factores de Riesgo , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Persona de Mediana Edad , Estudios de Cohortes , Modelos de Riesgos Proporcionales , Factores Sexuales , Cognición/fisiología , Disfunción Cognitiva , Anciano de 80 o más Años
8.
Nat Mater ; 21(10): 1144-1149, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35927432

RESUMEN

Van der Waals heterostructures with two-dimensional magnets offer a magnetic junction with an atomically sharp and clean interface. This attribute ensures that the magnetic layers maintain their intrinsic spin-polarized electronic states and spin-flipping scattering processes at a minimum level, a trait that can expand spintronic device functionalities. Here, using a van der Waals assembly of ferromagnetic Fe3GeTe2 with non-magnetic hexagonal boron nitride and WSe2 layers, we demonstrate electrically tunable, highly transparent spin injection and detection across the van der Waals interfaces. By varying an electrical bias, the net spin polarization of the injected carriers can be modulated and reversed in polarity, which leads to sign changes of the tunnelling magnetoresistance. We attribute the spin polarization reversals to sizable contributions from high-energy localized spin states in the metallic ferromagnet, so far inaccessible in conventional magnetic junctions. Such tunability of the spin-valve operations opens a promising route for the electronic control of next-generation low-dimensional spintronic device applications.

9.
Phys Rev Lett ; 131(23): 236903, 2023 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-38134786

RESUMEN

SrAs_{3} is a unique nodal-line semimetal that contains only a single nodal ring in the Brillouin zone, uninterrupted by any trivial bands near the Fermi energy. We performed axis-resolved optical reflection measurements on SrAs_{3} and observed that the optical conductivity exhibits flat absorption up to 129 meV in both the radial and axial directions, confirming the robustness of the universal power-law behavior of the nodal ring. The axis-resolved optical conductivity, in combination with theoretical calculations, further reveals fundamental properties beyond the flat absorption, including the overlap energy of the topological bands, the spin-orbit coupling gap along the nodal ring, and the geometric properties of the nodal ring such as the average ring radius, ring ellipticity, and velocity anisotropy. In addition, our temperature-dependent measurements revealed a spectral weight transfer between intraband and interband transitions, indicating a possible violation of the optical sum rule within the measured energy range.

10.
Thorac Cardiovasc Surg ; 71(8): 648-655, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-35917824

RESUMEN

BACKGROUND: A randomized controlled trial was designed to compare 1-year hemodynamic profiles and clinical outcomes after bioprosthetic aortic valve replacement (AVR) using a recently introduced (study group) and world-widely used (control group) bovine pericardial bioprostheses. This study evaluated early postoperative outcomes as a preliminary analysis. METHODS: The primary end point of the trial was the mean pressure gradient across the aortic valve (AVMPG) at 1 year after surgery. Patients were screened to enroll 70 patients in each group based on a noninferiority design. Early postoperative hemodynamic and clinical outcomes were compared between the two groups. RESULTS: There were no differences in baseline characteristics, including sex and body surface area (1.64 ± 0.18 vs. 1.65 ± 0.15 m2) between the two groups. The AVMPG on early postoperative echocardiography was 15.2 ± 4.6 mm Hg and 16.5 ± 6.2 mm Hg in the study and control groups, respectively (p = 0.177). Although AVMPG of the 19 mm prostheses was lower in the study group than in the control group (17.0 ± 6.3 mm Hg vs. 22.8 ± 6.6 mm Hg, p = 0.039), there were no significant differences in the effective orifice area in all patients (1.57 ± 0.41 cm2 vs. 1.53 ± 0.34 cm2, p = 0.568), and each valve size. The effective orifice area index was also similar between the two groups in overall (p = 0.352), and in each valve size. There were no significant differences in clinical outcomes including operative mortality and postoperative complications between the two groups. CONCLUSION: Early postoperative hemodynamic and clinical results after AVR using a recently introduced bovine pericardial valve were comparable with those using the control valve (NCT03796442).


Asunto(s)
Estenosis de la Válvula Aórtica , Bioprótesis , Implantación de Prótesis de Válvulas Cardíacas , Prótesis Valvulares Cardíacas , Humanos , Animales , Bovinos , Estenosis de la Válvula Aórtica/diagnóstico por imagen , Estenosis de la Válvula Aórtica/cirugía , Resultado del Tratamiento , Diseño de Prótesis , Válvula Aórtica/diagnóstico por imagen , Válvula Aórtica/cirugía , Hemodinámica
11.
Artículo en Inglés | MEDLINE | ID: mdl-37884030

RESUMEN

BACKGROUND: This randomized controlled trial was designed to compare 1-year hemodynamic performances and clinical outcomes after aortic valve replacement (AVR) using a recently introduced (the AVALUS group) and worldwide used (the CEPME group) bovine pericardial bioprostheses. METHODS: Patients were screened to enroll 70 patients in each group based on a noninferiority design. The primary endpoint of the trial was the mean pressure gradient across the aortic valve (AVMPG) at 1 year after surgery. One-year echocardiographic data were obtained from 92.1% (129 of 140 patients) of the study patients. RESULTS: There were no differences in baseline characteristics, including sex and body surface area (1.64 ± 0.18 vs. 1.65 ± 0.15 m2) between the groups. The AVMPG on 1-year echocardiography was 14.0 ± 4.3 and 13.9 ± 5.1 mmHg in the AVALUS and CEPME groups, respectively (the p-value for noninferiority was 0.0004). In the subgroup analyses for the respective size of the prostheses, AVMPG of the 19-mm prostheses was significantly lower in the AVALUS group than in the CEPME group (14.0 ± 4.3 vs. 20.0 ± 4.7 mmHg, p = 0.012), whereas those of the other sizes were not significantly different between the two groups. There were no significant differences in the effective orifice area (1.49 ± 0.40 vs. 1.53 ± 0.38 cm2, p = 0.500) or effective orifice area index (0.91 ± 0.22 vs 0.93 ± 0.23 cm2/m2, p = 0.570) in all the patients, or in the subgroup analysis for the 19-mm prosthesis. There were no differences in the 1-year clinical outcomes between the two groups. CONCLUSION: The 1-year hemodynamic and clinical outcomes of the AVALUS group were noninferior to those of the CEPME group (NCT03796442).

12.
Appl Microbiol Biotechnol ; 105(7): 2775-2785, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33713143

RESUMEN

Aromatic L-amino acid decarboxylases (AADCs) are ubiquitously found in higher organisms owing to their physiological role in the synthesis of neurotransmitters and alkaloids. However, bacterial AADC has not attracted much attention because of its rather limited availability and narrow substrate range. Here, we examined the biochemical properties of AADC from Bacillus atrophaeus (AADC-BA) and assessed the synthetic feasibility of the enzyme for the preparation of monoamine neurotransmitters. AADC-BA was expressed in Escherichia coli BL21(DE3) and the purified enzyme showed a specific activity of 2.6 ± 0.4 U/mg for 10 mM L-phenylalanine (L-Phe) at 37 °C. AADC-BA showed optimal pH and temperature ranges at 7-8 and 37-45 °C, respectively. The KM and kcat values for L-Phe were 7.2 mM and 7.4 s-1, respectively, at pH 7.0 and 37 °C. Comparison of the kinetic constants at different temperatures revealed that the temperature dependency of the enzyme was mainly determined by catalytic turnover rather than substrate binding. AADC-BA showed a broad substrate scope for various aromatic amino acids, including L-Phe, L-tryptophan (610% relative to L-Phe), L-tyrosine (12%), 3,4-dihydroxyphenyl-L-alanine (24%), 5-hydroxy-L-tryptophan (L-HTP, 71%), 4-chloro-L-phenylalanine (520%), and 4-nitro-L-phenylalanine (450%). Homology modeling and docking simulations were carried out and were consistent with the observed substrate specificity. To demonstrate the synthetic potential of AADC-BA, we carried out the production of serotonin by decarboxylation of L-HTP. The reaction yield of serotonin reached 98% after 1 h at the reaction conditions of 50 mM L-HTP and 4 U/mL AADC-BA. Moreover, we carried out preparative-scale decarboxylation of L-Phe (100 mM in 40-mL reaction mixture) and isolated the resulting 2-phenylethylamine (51% recovery yield). We expect that the broad substrate specificity of AADC-BA can be exploited to produce various aromatic biogenic amines. KEY POINTS: • AADC-BA showed broad substrate specificity for various aromatic amino acids. • The substrate specificity was elucidated by in silico structural modeling. • The synthetic potential of AADC-BA was demonstrated for the production of biogenic amines.


Asunto(s)
Descarboxilasas de Aminoácido-L-Aromático , Bacillus , 5-Hidroxitriptófano , Descarboxilasas de Aminoácido-L-Aromático/genética , Serotonina , Triptófano
13.
J Biomed Sci ; 27(1): 21, 2020 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-31906951

RESUMEN

BACKGROUND: Melatonin (5-methoxy-N-acetyltryptamine), a hormone produced in the pineal gland, has a variety of biological functions as an antioxidant, but a functional role of melatonin in the regulation of intestinal mucin (Muc) production during bacterial infection has yet to be described in detail. In this study, we investigate the effects of melatonin during Muc2 repression elicited by the Gram-negative bacterium V. vulnificus. METHODS: Mucus-secreting human HT29-MTX cells were used to study the functional role of melatonin during Muc2 depletion induced by the recombinant protein (r) VvpM produced by V. vulnificus. The regulatory effects of melatonin coupling with melatonin receptor 2 (MT2) on the production of reactive oxygen species (ROS), the activation of PKCδ and ERK, and the hypermethylation of the Muc2 promoter as induced by rVvpM were examined. Experimental mouse models of V. vulnificus infection were used to study the role of melatonin and how it neutralizes the bacterial toxin activity related to Muc2 repression. RESULTS: Recombinant protein (r) VvpM significantly reduced the level of Muc2 in HT29-MTX cells. The repression of Muc2 induced by rVvpM was significantly restored upon a treatment with melatonin (1 µM), which had been inhibited by the knockdown of MT2 coupling with Gαq and the NADPH oxidase subunit p47 phox. Melatonin inhibited the ROS-mediated phosphorylation of PKCδ and ERK responsible for region-specific hypermethylation in the Muc2 promoter in rVvpM-treated HT29-MTX cells. In the mouse models of V. vulnificus infection, treatment with melatonin maintained the level of Muc2 expression in the intestine. In addition, the mutation of the VvpM gene from V. vulnificus exhibited an effect similar to that of melatonin. CONCLUSIONS: These results demonstrate that melatonin acting on MT2 inhibits the hypermethylation of the Muc2 promoter to restore the level of Muc2 production in intestinal epithelial cells infected with V. vulnificus.


Asunto(s)
Toxinas Bacterianas/metabolismo , Metilación de ADN , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Melatonina/farmacología , Mucina 2/biosíntesis , Receptor de Melatonina MT2/metabolismo , Vibriosis/metabolismo , Vibrio vulnificus/metabolismo , Animales , Toxinas Bacterianas/farmacología , Células HT29 , Humanos , Ratones , Vibriosis/patología
14.
Cell Commun Signal ; 18(1): 123, 2020 08 12.
Artículo en Inglés | MEDLINE | ID: mdl-32787872

RESUMEN

BACKGROUND: Neurodegeneration is a representative phenotype of patients with chronic alcoholism. Ethanol-induced calcium overload causes NOD-like receptor protein 3 (NLRP3) inflammasome formation and an imbalance in mitochondrial dynamics, closely associated with the pathogenesis of neurodegeneration. However, how calcium regulates this process in neuronal cells is poorly understood. Therefore, the present study investigated the detailed mechanism of calcium-regulated mitochondrial dynamics and NLRP3 inflammasome formation in neuronal cells by ethanol. METHODS: In this study, we used the SK-N-MC human neuroblastoma cell line. To confirm the expression level of the mRNA and protein, real time quantitative PCR and western blot were performed. Co-immunoprecipitation and Immunofluorescence staining were conducted to confirm the complex formation or interaction of the proteins. Flow cytometry was used to analyze intracellular calcium, mitochondrial dysfunction and neuronal apoptosis. RESULTS: Ethanol increased cleaved caspase-3 levels and mitochondrial reactive oxygen species (ROS) generation associated with neuronal apoptosis. In addition, ethanol increased protein kinase A (PKA) activation and cAMP-response-element-binding protein (CREB) phosphorylation, which increased N-methyl-D-aspartate receptor (NMDAR) expression. Ethanol-increased NMDAR induced intracellular calcium overload and calmodulin-dependent protein kinase II (CaMKII) activation leading to phosphorylation of dynamin-related protein 1 (Drp1) and c-Jun N-terminal protein kinase 1 (JNK1). Drp1 phosphorylation promoted Drp1 translocation to the mitochondria, resulting in excessive mitochondrial fission, mitochondrial ROS accumulation, and loss of mitochondrial membrane potential, which was recovered by Drp1 inhibitor pretreatment. Ethanol-induced JNK1 phosphorylation activated the NLRP3 inflammasome that induced caspase-1 dependent mitophagy inhibition, thereby exacerbating ROS accumulation and causing cell death. Suppressing caspase-1 induced mitophagy and reversed the ethanol-induced apoptosis in neuronal cells. CONCLUSIONS: Our results demonstrated that ethanol upregulated NMDAR-dependent CaMKII phosphorylation which is essential for Drp1-mediated excessive mitochondrial fission and the JNK1-induced NLRP3 inflammasome activation resulting in neuronal apoptosis. Video abstract.


Asunto(s)
Apoptosis , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Dinaminas/metabolismo , Etanol/farmacología , Inflamasomas/metabolismo , Dinámicas Mitocondriales , Proteína Quinasa 8 Activada por Mitógenos/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Neuronas/metabolismo , Apoptosis/efectos de los fármacos , Calcio/metabolismo , Caspasa 1/metabolismo , Línea Celular Tumoral , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Activación Enzimática/efectos de los fármacos , Humanos , Espacio Intracelular/metabolismo , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Dinámicas Mitocondriales/efectos de los fármacos , Mitofagia/efectos de los fármacos , Modelos Biológicos , Neuronas/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal/efectos de los fármacos , Ubiquitina-Proteína Ligasas/metabolismo
15.
Ann Vasc Surg ; 66: 554-565, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31706994

RESUMEN

BACKGROUND: The association between oxidized low-density lipoprotein (OxLDL) and plaque instability in coronary and carotid artery disease is well established. However, the association between OxLDL and the histologic changes of plaque in peripheral artery disease has not been clearly elucidated. This study aims to investigate the association between plasma OxLDL and histologic plaque instability in patients with peripheral artery disease. METHODS: Prospectively obtained plaques from 48 patients who underwent endovascular atherectomy (n = 20), surgical endarterectomy (n = 9), or bypass surgery (n = 19) for treatment of atherosclerotic femoropopliteal artery disease were evaluated for histologic fibrosis, sclerosis, calcification, necrosis, cholesterol cleft, and foamy macrophages using hematoxylin and eosin, oil red O, and immunohistochemical staining. Unstable plaques were defined as plaques that were positive for foamy macrophages and with lipid content of more than 10% of the total plaque area. Plasma OxLDL levels were measured using an enzyme-linked immunosorbent assay (Mercodia AB, Uppsala, Sweden). RESULTS: Of the 48 patients, 26 (54%) had unstable plaques. The unstable plaque group was younger, had fewer angiographic total occlusions, less calcification, and more CD68-positive and LOX-1-positive cells than the stable plaque group. Plasma OxLDL levels were significantly higher in the unstable plaque group than in the stable plaque group (57.4 ± 13.9 vs. 47.2 ± 13.6 U/L, P = 0.014). Multivariate analysis revealed that plasma OxLDL level, smoking, angiographic nontotal occlusion, and statin nonuse were independent predictors of unstable plaque. CONCLUSIONS: Among patients with peripheral artery disease, the histologic instability of femoropopliteal plaque was independently associated with high plasma OxLDL, smoking, nontotal occlusion, and statin nonuse. Further large-scale studies are necessary to evaluate the role of noninvasive OxLDL measurement for predicting plaque instability and future adverse vascular event.


Asunto(s)
Lipoproteínas LDL/sangre , Enfermedad Arterial Periférica/sangre , Enfermedad Arterial Periférica/patología , Placa Aterosclerótica , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedad Arterial Periférica/terapia , Valor Predictivo de las Pruebas , Pronóstico , Estudios Prospectivos , República de Corea , Factores de Riesgo , Rotura Espontánea , Regulación hacia Arriba
16.
Nano Lett ; 19(3): 1814-1820, 2019 03 13.
Artículo en Inglés | MEDLINE | ID: mdl-30779586

RESUMEN

We have achieved heteroepitaxial stacking of a van der Waals ( vdW) monolayer metal, 1T'-WTe2, and a semiconductor, 2H-WSe2, in which a distinctively low contact barrier was established across a clean epitaxial vdW gap. Our epitaxial 1T'-WTe2 films were identified as a semimetal by low temperature transport and showed the robust breakdown current density of 5.0 × 107 A/cm2. In comparison with a series of planar metal contacts, our epitaxial vdW contact was identified to possess intrinsic Schottky barrier heights below 100 meV for both electron and hole injections, contributing to superior ambipolar field-effect transistor (FET) characteristics, i.e., higher FET mobilities and higher on-off current ratios at smaller threshold gate voltages. We discuss our observations around the critical roles of the epitaxial vdW heterointerfaces, such as incommensurate stacking sequences and absence of extrinsic interfacial defects that are inaccessible by other contact methods.

17.
Nat Mater ; 17(9): 794-799, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-30013056

RESUMEN

Topological semimetals host electronic structures with several band-contact points or lines and are generally expected to exhibit strong topological responses. Up to now, most work has been limited to non-magnetic materials and the interplay between topology and magnetism in this class of quantum materials has been largely unexplored. Here we utilize theoretical calculations, magnetotransport and angle-resolved photoemission spectroscopy to propose Fe3GeTe2, a van der Waals material, as a candidate ferromagnetic (FM) nodal line semimetal. We find that the spin degree of freedom is fully quenched by the large FM polarization, but the line degeneracy is protected by crystalline symmetries that connect two orbitals in adjacent layers. This orbital-driven nodal line is tunable by spin orientation due to spin-orbit coupling and produces a large Berry curvature, which leads to a large anomalous Hall current, angle and factor. These results demonstrate that FM topological semimetals hold significant potential for spin- and orbital-dependent electronic functionalities.

18.
Phys Rev Lett ; 123(20): 206401, 2019 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-31809082

RESUMEN

We demonstrate that the excitonic insulator ground state of Ta_{2}NiSe_{5} can be electrically controlled by electropositive surface adsorbates. Our studies utilizing angle-resolved photoemission spectroscopy reveal intriguing wave-vector-dependent deformations of the characteristic flattop valence band of this material upon potassium adsorption. The observed band deformation indicates a reduction of the single-particle band gap due to the Stark effect near the surface. The present study provides the foundation for the electrical tuning of the many-body quantum states in excitonic insulators.

19.
Phys Rev Lett ; 122(20): 207201, 2019 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-31172742

RESUMEN

We propose a novel origin of magnetic anisotropy to explain the unusual magnetic behaviors of layered ferromagnetic Cr compounds (3d^{3}) wherein the anisotropy field varies from ≲0.01 to ∼3 T on changing the ligand atom in a common hexagonal structure. The effect of the ligand p orbital spin-orbit (LS) coupling on the magnetic anisotropy is explored by using four-site full multiplet cluster model calculations for energies involving the superexchange interaction at different spin axes. Our calculation shows that the anisotropy energy, which is the energy difference for different spin axes, is strongly affected not only by the LS coupling strength but also by the degree of p-d covalency in the layered geometry. This anisotropy energy involving the superexchange appears to dominate the magnetic anisotropy and even explains the giant magnetic anisotropy as large as 3 T observed in CrI_{3}.

20.
Circ J ; 83(7): 1572-1580, 2019 06 25.
Artículo en Inglés | MEDLINE | ID: mdl-31130585

RESUMEN

BACKGROUND: Some studies comparing minimally invasive direct coronary artery bypass (MIDCAB) and percutaneous coronary intervention (PCI) have reported MIDCAB's superiority, but they did not investigate contemporary PCI with newer generation drug-eluting stents (DES). We compared clinical outcomes after MIDCAB with previously reported outcomes after PCI with second-generation DES.Methods and Results:We retrospectively reviewed the records of patients treated with MIDCAB. Baseline characteristics and clinical outcomes after MIDCAB were compared with those for left anterior descending artery disease treated via PCI. The primary outcomes were major adverse cardiovascular and cerebrovascular events (MACCE), a composite of cardiovascular death, non-fatal myocardial infarction, ischemic stroke, and target vessel revascularization (TVR). A propensity score-matching (PSM) analysis was conducted to adjust for between-group differences in baseline characteristics. We analyzed 77 patients treated with MIDCAB and 2,206 treated with PCI. The MIDCAB group was older and had more severe coronary disease and a higher incidence of left ventricular dysfunction. Over a 3-year follow-up, the PCI group had favorable MACCE outcomes. After PSM, there were no between-group differences in MACCE (MIDCAB, 15.6% vs. PCI, 23.4%; hazard ratio [HR], 0.80; 95% CI: 0.38-1.68, P=0.548) or TVR (MIDCAB, 2.6% vs. PCI, 5.2%; HR, 0.51; 95% CI: 0.10-3.09, P=0.509). CONCLUSIONS: Clinical outcomes were similar between MIDCAB and PCI using second-generation DES over 3 years of follow-up.


Asunto(s)
Puente de Arteria Coronaria/efectos adversos , Enfermedad de la Arteria Coronaria , Stents Liberadores de Fármacos/efectos adversos , Intervención Coronaria Percutánea/efectos adversos , Complicaciones Posoperatorias/epidemiología , Disfunción Ventricular Izquierda , Anciano , Anciano de 80 o más Años , Enfermedad de la Arteria Coronaria/epidemiología , Enfermedad de la Arteria Coronaria/cirugía , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Disfunción Ventricular Izquierda/epidemiología , Disfunción Ventricular Izquierda/etiología
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