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| 2. |
- Yoo, Taekyeong, et al.
(författare)
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Disease-specific eQTL screening reveals an anti-fibrotic effect of AGXT2 in non-alcoholic fatty liver disease.
- 2021
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Ingår i: Journal of hepatology. - : Elsevier BV. - 1600-0641 .- 0168-8278. ; 75:3, s. 514-523
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Tidskriftsartikel (refereegranskat)abstract
- Nonalcoholic fatty liver disease (NAFLD) poses an impending clinical burden. Genome-wide association studies have revealed a limited contribution of genomic variants to the disease, requiring alternative but robust approaches to identify disease-associated variants and genes. We carried out a disease-specific expression quantitative trait loci (eQTL) screen to identify novel genetic factors that specifically act on NAFLD progression on the basis of genotype.We recruited 125 Korean biopsy-proven NAFLD patients and healthy individuals and performed eQTL analyses using 21,272 transcripts and 3,234,941 genotyped and imputed SNPs. We then selected eQTLs that were detected only in the NAFLD group, but not in the control group (i.e., NAFLD-eQTLs). An additional cohort of 162 Korean NAFLD individuals was used for replication. The function of the selected eQTL toward NAFLD development was validated using HepG2, primary hepatocytes and NAFLD mouse models.The NAFLD-specific eQTL screening yielded 242 loci. Among them, AGXT2, encoding alanine-glyoxylate aminotransferase 2, displayed decreased expression in NAFLD patients homozygous for the non-reference allele of rs2291702, compared to no-NAFLD subjects with the same genotype (P = 4.79 × 10-6). This change was replicated in an additional 162 individuals, yielding a combined P-value of 8.05 × 10-8 from a total of 245 NAFLD patients and 48 controls. Knockdown of AGXT2 induced palmitate-overloaded hepatocyte death by increasing ER stress, and exacerbated NAFLD diet-induced liver fibrosis in mice. However, overexpression of AGXT2 reversely attenuated liver fibrosis and steatosis as well.We implicate a new molecular role of AGXT2 in NAFLD. Our overall approach will serve as an efficient tool for uncovering novel genetic factors that contribute to liver steatosis and fibrosis in patients with NAFLD.Elucidating causal genes for NAFLD has been challenging due to limited tissue availability and the polygenic nature of the disease. Using liver and blood samples from 125 biopsy-proven NAFLD and no-NAFLD Korean individuals and an additional 162 individuals for replication, we devised a new analytic method to identify causal genes. Among the candidates, we found that AGXT2-rs2291702 protects against liver fibrosis in a genotype-dependent manner with the potential for therapeutic interventions. Our approach enables the discovery of NAFLD causal genes that act on the basis of genotype.
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| 3. |
- Cheon, Jae Yeong, et al.
(författare)
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Ordered mesoporous porphyrinic carbons with very high electrocatalytic activity for the oxygen reduction reaction
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3, s. 2715-
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Tidskriftsartikel (refereegranskat)abstract
- The high cost of the platinum-based cathode catalysts for the oxygen reduction reaction (ORR) has impeded the widespread application of polymer electrolyte fuel cells. We report on a new family of non-precious metal catalysts based on ordered mesoporous porphyrinic carbons (M-OMPC; M = Fe, Co, or FeCo) with high surface areas and tunable pore structures, which were prepared by nanocasting mesoporous silica templates with metalloporphyrin precursors. The FeCo-OMPC catalyst exhibited an excellent ORR activity in an acidic medium, higher than other non-precious metal catalysts. It showed higher kinetic current at 0.9 V than Pt/C catalysts, as well as superior long-term durability and MeOH-tolerance. Density functional theory calculations in combination with extended X-ray absorption fine structure analysis revealed a weakening of the interaction between oxygen atom and FeCo-OMPC compared to Pt/C. This effect and high surface area of FeCo-OMPC appear responsible for its significantly high ORR activity.
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| 4. |
- Birney, Ewan, et al.
(författare)
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Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7146, s. 799-816
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Tidskriftsartikel (refereegranskat)abstract
- We report the generation and analysis of functional data from multiple, diverse experiments performed on a targeted 1% of the human genome as part of the pilot phase of the ENCODE Project. These data have been further integrated and augmented by a number of evolutionary and computational analyses. Together, our results advance the collective knowledge about human genome function in several major areas. First, our studies provide convincing evidence that the genome is pervasively transcribed, such that the majority of its bases can be found in primary transcripts, including non-protein-coding transcripts, and those that extensively overlap one another. Second, systematic examination of transcriptional regulation has yielded new understanding about transcription start sites, including their relationship to specific regulatory sequences and features of chromatin accessibility and histone modification. Third, a more sophisticated view of chromatin structure has emerged, including its inter-relationship with DNA replication and transcriptional regulation. Finally, integration of these new sources of information, in particular with respect to mammalian evolution based on inter- and intra-species sequence comparisons, has yielded new mechanistic and evolutionary insights concerning the functional landscape of the human genome. Together, these studies are defining a path for pursuit of a more comprehensive characterization of human genome function.
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| 5. |
- Lee, Seung Won, et al.
(författare)
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Physical activity and the risk of SARS-CoV-2 infection, severe COVID-19 illness and COVID-19 related mortality in South Korea: a nationwide cohort study
- 2022
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Ingår i: British Journal of Sports Medicine. - : BMJ PUBLISHING GROUP. - 0306-3674 .- 1473-0480. ; 56:16, s. 901-912
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To determine the potential associations between physical activity and risk of SARS-CoV-2 infection, severe illness from COVID-19 and COVID-19 related death using a nationwide cohort from South Korea. Methods Data regarding 212 768 Korean adults (age >= 20 years), who tested for SARS-CoV-2, from 1 January 2020 to 30 May 2020, were obtained from the National Health Insurance Service of South Korea and further linked with the national general health examination from 1 January 2018 to 31 December 2019 to assess physical activity levels. SARS-CoV-2 positivity, severe COVID-19 illness and COVID-19 related death were the main outcomes. The observation period was between 1 January 2020 and 31 July 2020. Results Out of 76 395 participants who completed the general health examination and were tested for SARS-CoV-2, 2295 (3.0%) were positive for SARS-CoV-2, 446 (0.58%) had severe illness from COVID-19 and 45 (0.059%) died from COVID-19. Adults who engaged in both aerobic and muscle strengthening activities according to the 2018 physical activity guidelines had a lower risk of SARS-CoV-2 infection (2.6% vs 3.1%; adjusted relative risk (aRR), 0.85; 95% CI 0.72 to 0.96), severe COVID-19 illness (0.35% vs 0.66%; aRR 0.42; 95% CI 0.19 to 0.91) and COVID-19 related death (0.02% vs 0.08%; aRR 0.24; 95% CI 0.05 to 0.99) than those who engaged in insufficient aerobic and muscle strengthening activities. Furthermore, the recommended range of metabolic equivalent task (MET; 500-1000 MET min/week) was associated with the maximum beneficial effect size for reduced risk of SARS-CoV-2 infection (aRR 0.78; 95% CI 0.66 to 0.92), severe COVID-19 illness (aRR 0.62; 95% CI 0.43 to 0.90) and COVID-19 related death (aRR 0.17; 95% CI 0.07 to 0.98). Similar patterns of association were observed in different sensitivity analyses. Conclusion Adults who engaged in the recommended levels of physical activity were associated with a decreased likelihood of SARS-CoV-2 infection, severe COVID-19 illness and COVID-19 related death. Our findings suggest that engaging in physical activity has substantial public health value and demonstrates potential benefits to combat COVID-19.
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| 6. |
- Cho, Hyunsoo, et al.
(författare)
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YAP and TAZ Negatively Regulate Prox1 During Developmental and Pathologic Lymphangiogenesis
- 2019
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Ingår i: Circulation Research. - : Lippincott Williams & Wilkins. - 0009-7330 .- 1524-4571. ; 124:2, s. 225-242
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: The Hippo pathway governs cellular differentiation, morphogenesis, and homeostasis, but how it regulates these processes in lymphatic vessels is unknown. Objective: We aimed to reveal the role of the final effectors of the Hippo pathway, YAP (Yes-associated protein) and TAZ (transcriptional coactivator with PDZ-binding motif), in lymphatic endothelial cell (LEC) differentiation, morphogenesis, and homeostasis. Methods and Results: During mouse embryonic development, LEC-specific depletion of Yap/Taz disturbed both plexus patterning and valve initiation with upregulated Prox1 (prospero homeobox 1). Conversely, LEC-specific YAP/TAZ hyperactivation impaired lymphatic specification and restricted lymphatic sprouting with profoundly downregulated Prox1. Notably, lymphatic YAP/TAZ depletion or hyperactivation aggravated or attenuated pathological lymphangiogenesis in mouse cornea. Mechanistically, VEGF (vascular endothelial growth factor)-C activated canonical Hippo signaling pathway in LECs. Indeed, repression of PROX1 transcription by YAP/TAZ hyperactivation was mediated by recruitment of NuRD (nucleosome remodeling and histone deacetylase) complex and endogenous binding activity of TEAD (TEA domain family members) to the PROX1 promoter. Furthermore, YAP/TAZ hyperactivation enhanced MYC signaling and inhibited CDKN1C, leading to cell cycle dysregulation and aberrant proliferation. Conclusions: We find that YAP and TAZ play promoting roles in remodeling lymphatic plexus patterning and postnatal lymphatic valve maintenance by negatively regulating Prox1 expression. We further show that YAP and TAZ act as plastic regulators of lymphatic identity and define the Hippo signaling-mediated PROX1 transcriptional programing as a novel dynamic checkpoint underlying LEC plasticity and pathophysiology.
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| 7. |
- Choi, Joong Il Jake, et al.
(författare)
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Atomic-scale view of stability and degradation of single-crystal MAPbBr(3) surfaces
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 7:36, s. 20760-20766
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Tidskriftsartikel (refereegranskat)abstract
- While organic-inorganic hybrid perovskite solar cells are emerging as promising candidates for next-generation solar cells with fascinating power conversion efficiency, the instability of perovskites remains a significant bottleneck for their commercialization. An atomic scale understanding of the degradation of hybrid perovskites, however, is only in its beginning stages because of the difficulty in preparing well-defined surface conditions for characterization. Using atomic force microscopy at ultra-high vacuum and room temperature, we report the first direct observation of the degradation process of a cleaved methylammonium lead bromide, MAPbBr(3) (MA: CH3NH3+), single crystal. Upon in situ cleavage, atomic force microscopy images show large flat terraces with monolayer height steps, which correspond to the surface of cubic MAPbBr(3) with methylammonium ligand termination. While this surface can be prepared via the cleavage process and is energetically stable, we observe that after several weeks under dark and vacuum conditions it degrades and produces clusters surrounded by pits. Guided by density functional theory calculations, we propose a degradation pathway that initiates even at low humidity levels and leads to the formation of surface PbBr2 species. We finally identify the electronic structure of the MA-bromine-terminated flat surface and find that it is correlated with a strong field-induced degradation of the MAPbBr(3) only at positive sample bias voltages.
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| 8. |
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| 9. |
- Lee, Hyun-Seob, et al.
(författare)
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Foxa2 and Nurr1 Synergistically Yield A9 Nigral Dopamine Neurons Exhibiting Improved Differentiation, Function, and Cell Survival
- 2010
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1549-4918 .- 1066-5099. ; 28:3, s. 501-512
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Tidskriftsartikel (refereegranskat)abstract
- Effective dopamine (DA) neuron differentiation from neural precursor cells (NPCs) is prerequisite for precursor/stem cell-based therapy of Parkinson's disease (PD). Nurr1, an orphan nuclear receptor, has been reported as a transcription factor that can drive DA neuron differentiation from non-dopaminergic NPCs in vitro. However, Nurr1 alone neither induces full neuronal maturation nor expression of proteins found specifically in midbrain DA neurons. In addition, Nurr1 expression is inefficient in inducing DA phenotype expression in NPCs derived from certain species such as mouse and human. We show here that Foxa2, a forkhead transcription factor whose role in midbrain DA neuron development was recently revealed, synergistically cooperates with Nurr1 to induce DA phenotype acquisition, midbrain-specific gene expression, and neuronal maturation. Thus, the combinatorial expression of Nurr1 and Foxa2 in NPCs efficiently yielded fully differentiated nigral (A9)-type midbrain neurons with clearly detectable DA neuronal activities. The effects of Foxa2 in DA neuron generation were observed regardless of the brain regions or species from which NPCs were derived. Furthermore, DA neurons generated by ectopic Foxa2 expression were more resistant to toxins. Importantly, Foxa2 expression resulted in a rapid cell cycle exit and reduced cell proliferation. Consistently, transplantation of NPCs transduced with Nurr1 and Foxa2 generated grafts enriched with midbrain-type DA neurons but reduced number of proliferating cells, and significantly reversed motor deficits in a rat PD model. Our findings can be applied to ongoing attempts to develop an efficient and safe precursor/stem cell-based therapy for PD. STEM CELLS 2010; 28: 501-512
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| 10. |
- Reddy, A. Satyanarayana, et al.
(författare)
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Ultrathin titania coating for high-temperature stable SiO(2)/Pt nanocatalysts
- 2011
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 47, s. 8412-8414
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Tidskriftsartikel (refereegranskat)abstract
- The facile synthesis of silica supported platinum nanoparticles with ultrathin titania coating to enhance metal-support interactions suitable for high temperature reactions is reported, as thermal and structure stability of metal nanoparticles is important for catalytic reactions.
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