24 results on '"Nguyen, L."'
Search Results
2. Structure and function of Parkin E3 ubiquitin ligase reveals aspects of RING and HECT ligases
- Author
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Riley, B.E., primary, Lougheed, J.C., additional, Callaway, K., additional, Velasquez, M., additional, Brecht, E., additional, Nguyen, L., additional, Shaler, T., additional, Walker, D., additional, Yang, Y., additional, Regnstrom, K., additional, Diep, L., additional, Zhang, Z., additional, Chiou, S., additional, Bova, M., additional, Artis, D.R., additional, Yao, N., additional, Baker, J., additional, Yednock, T., additional, and Johnston, J.A., additional
- Published
- 2013
- Full Text
- View/download PDF
3. Author Correction: Environmental, economic, and social sustainability in aquaculture: the aquaculture performance indicators.
- Author
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Garlock TM, Asche F, Anderson JL, Eggert H, Anderson TM, Che B, Chávez CA, Chu J, Chukwuone N, Dey MM, Fitzsimmons K, Flores J, Guillen J, Kumar G, Liu L, Llorente I, Nguyen L, Nielsen R, Pincinato RBM, Sudhakaran PO, Tibesigwa B, and Tveteras R
- Published
- 2024
- Full Text
- View/download PDF
4. Environmental, economic, and social sustainability in aquaculture: the aquaculture performance indicators.
- Author
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Garlock TM, Asche F, Anderson JL, Eggert H, Anderson TM, Che B, Chávez CA, Chu J, Chukwuone N, Dey MM, Fitzsimmons K, Flores J, Guillen J, Kumar G, Liu L, Llorente I, Nguyen L, Nielsen R, Pincinato RBM, Sudhakaran PO, Tibesigwa B, and Tveteras R
- Subjects
- Humans, Environment, Animals, Sustainable Development economics, Fisheries economics, Aquaculture economics, Aquaculture methods, Conservation of Natural Resources methods, Conservation of Natural Resources economics
- Abstract
Aquaculture is a rapidly growing food production technology, but there are significant concerns related to its environmental impact and adverse social effects. We examine aquaculture outcomes in a three pillars of sustainability framework by analyzing data collected using the Aquaculture Performance Indicators. Using this approach, comparable data has been collected for 57 aquaculture systems worldwide on 88 metrics that measure social, economic, or environmental outcomes. We first examine the relationships among the three pillars of sustainability and then analyze performance in the three pillars by technology and species. The results show that economic, social, and environmental outcomes are, on average, mutually reinforced in global aquaculture systems. However, the analysis also shows significant variation in the degree of sustainability in different aquaculture systems, and weak performance of some production systems in some dimensions provides opportunity for innovative policy measures and investment to further align sustainability objectives., (© 2024. The Author(s).)
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- 2024
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- View/download PDF
5. Author Correction: CBP-HSF2 structural and functional interplay in Rubinstein-Taybi neurodevelopmental disorder.
- Author
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de Thonel A, Ahlskog JK, Daupin K, Dubreuil V, Berthelet J, Chaput C, Pires G, Leonetti C, Abane R, Barris LC, Leray I, Aalto AL, Naceri S, Cordonnier M, Benasolo C, Sanial M, Duchateau A, Vihervaara A, Puustinen MC, Miozzo F, Fergelot P, Lebigot É, Verloes A, Gressens P, Lacombe D, Gobbo J, Garrido C, Westerheide SD, David L, Petitjean M, Taboureau O, Rodrigues-Lima F, Passemard S, Sabéran-Djoneidi D, Nguyen L, Lancaster M, Sistonen L, and Mezger V
- Published
- 2023
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6. Author Correction: Effectiveness of mRNA COVID-19 vaccine booster doses against Omicron severe outcomes.
- Author
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Grewal R, Nguyen L, Buchan SA, Wilson SE, Nasreen S, Austin PC, Brown KA, Fell DB, Gubbay JB, Schwartz KL, Tadrous M, Wilson K, and Kwong JC
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- 2023
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7. Effectiveness of mRNA COVID-19 vaccine booster doses against Omicron severe outcomes.
- Author
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Grewal R, Nguyen L, Buchan SA, Wilson SE, Nasreen S, Austin PC, Brown KA, Fell DB, Gubbay JB, Schwartz KL, Tadrous M, Wilson K, and Kwong JC
- Subjects
- Adult, Humans, COVID-19 Vaccines, SARS-CoV-2, Ontario epidemiology, RNA, Messenger, COVID-19 prevention & control
- Abstract
We estimated the effectiveness of booster doses of monovalent mRNA COVID-19 vaccines against Omicron-associated severe outcomes among adults in Ontario, Canada. We used a test-negative design to estimate vaccine effectiveness (VE) against hospitalization or death among SARS-CoV-2-tested adults aged ≥50 years from January 2 to October 1, 2022, stratified by age and time since vaccination. We also compared VE during BA.1/BA.2 and BA.4/BA.5 sublineage predominance. We included 11,160 cases and 62,880 tests for test-negative controls. Depending on the age group, compared to unvaccinated adults, VE was 91-98% 7-59 days after a third dose, waned to 76-87% after ≥240 days, was restored to 92-97% 7-59 days after a fourth dose, and waned to 86-89% after ≥120 days. VE was lower and declined faster during BA.4/BA.5 versus BA.1/BA.2 predominance, particularly after ≥120 days. Here we show that booster doses of monovalent mRNA COVID-19 vaccines restored strong protection against severe outcomes for at least 3 months after vaccination. Across the entire study period, protection declined slightly over time, but waned more during BA.4/BA.5 predominance., (© 2023. Crown.)
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- 2023
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8. CBP-HSF2 structural and functional interplay in Rubinstein-Taybi neurodevelopmental disorder.
- Author
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de Thonel A, Ahlskog JK, Daupin K, Dubreuil V, Berthelet J, Chaput C, Pires G, Leonetti C, Abane R, Barris LC, Leray I, Aalto AL, Naceri S, Cordonnier M, Benasolo C, Sanial M, Duchateau A, Vihervaara A, Puustinen MC, Miozzo F, Fergelot P, Lebigot É, Verloes A, Gressens P, Lacombe D, Gobbo J, Garrido C, Westerheide SD, David L, Petitjean M, Taboureau O, Rodrigues-Lima F, Passemard S, Sabéran-Djoneidi D, Nguyen L, Lancaster M, Sistonen L, and Mezger V
- Subjects
- Humans, Histones genetics, Mutation, E1A-Associated p300 Protein genetics, E1A-Associated p300 Protein metabolism, CREB-Binding Protein genetics, CREB-Binding Protein metabolism, Heat-Shock Proteins genetics, Heat-Shock Proteins metabolism, Neurodevelopmental Disorders genetics, Neurodevelopmental Disorders pathology, Rubinstein-Taybi Syndrome genetics, Rubinstein-Taybi Syndrome pathology, Transcription Factors genetics, Transcription Factors metabolism
- Abstract
Patients carrying autosomal dominant mutations in the histone/lysine acetyl transferases CBP or EP300 develop a neurodevelopmental disorder: Rubinstein-Taybi syndrome (RSTS). The biological pathways underlying these neurodevelopmental defects remain elusive. Here, we unravel the contribution of a stress-responsive pathway to RSTS. We characterize the structural and functional interaction between CBP/EP300 and heat-shock factor 2 (HSF2), a tuner of brain cortical development and major player in prenatal stress responses in the neocortex: CBP/EP300 acetylates HSF2, leading to the stabilization of the HSF2 protein. Consequently, RSTS patient-derived primary cells show decreased levels of HSF2 and HSF2-dependent alteration in their repertoire of molecular chaperones and stress response. Moreover, we unravel a CBP/EP300-HSF2-N-cadherin cascade that is also active in neurodevelopmental contexts, and show that its deregulation disturbs neuroepithelial integrity in 2D and 3D organoid models of cerebral development, generated from RSTS patient-derived iPSC cells, providing a molecular reading key for this complex pathology., (© 2022. The Author(s).)
- Published
- 2022
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9. Machine learning-based tissue of origin classification for cancer of unknown primary diagnostics using genome-wide mutation features.
- Author
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Nguyen L, Van Hoeck A, and Cuppen E
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- Genome, Humans, Machine Learning, Mutation, Neoplasms, Unknown Primary diagnosis, Neoplasms, Unknown Primary genetics
- Abstract
Cancers of unknown primary (CUP) origin account for ∼3% of all cancer diagnoses, whereby the tumor tissue of origin (TOO) cannot be determined. Using a uniformly processed dataset encompassing 6756 whole-genome sequenced primary and metastatic tumors, we develop Cancer of Unknown Primary Location Resolver (CUPLR), a random forest TOO classifier that employs 511 features based on simple and complex somatic driver and passenger mutations. CUPLR distinguishes 35 cancer (sub)types with ∼90% recall and ∼90% precision based on cross-validation and test set predictions. We find that structural variant derived features increase the performance and utility for classifying specific cancer types. With CUPLR, we could determine the TOO for 82/141 (58%) of CUP patients. Although CUPLR is based on machine learning, it provides a human interpretable graphical report with detailed feature explanations. The comprehensive output of CUPLR complements existing histopathological procedures and can enable improved diagnostics for CUP patients., (© 2022. The Author(s).)
- Published
- 2022
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10. Publisher Correction: ATP-citrate lyase promotes axonal transport across species.
- Author
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Even A, Morelli G, Turchetto S, Shilian M, Bail RL, Laguesse S, Krusy N, Brisker A, Brandis A, Inbar S, Chariot A, Saudou F, Dietrich P, Dragatsis I, Brone B, Broix L, Rigo JM, Weil M, and Nguyen L
- Published
- 2021
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11. ATP-citrate lyase promotes axonal transport across species.
- Author
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Even A, Morelli G, Turchetto S, Shilian M, Bail RL, Laguesse S, Krusy N, Brisker A, Brandis A, Inbar S, Chariot A, Saudou F, Dietrich P, Dragatsis I, Brone B, Broix L, Rigo JM, Weil M, and Nguyen L
- Subjects
- ATP Citrate (pro-S)-Lyase genetics, Acetyl Coenzyme A metabolism, Acetylation, Acetyltransferases genetics, Animals, Axonal Transport genetics, Drosophila melanogaster, Dysautonomia, Familial metabolism, Female, Fibroblasts metabolism, Humans, Larva, Male, Mice, Microtubules metabolism, Protein Processing, Post-Translational, Tubulin metabolism, ATP Citrate (pro-S)-Lyase metabolism, Axonal Transport physiology
- Abstract
Microtubule (MT)-based transport is an evolutionary conserved process finely tuned by posttranslational modifications. Among them, α-tubulin acetylation, primarily catalyzed by a vesicular pool of α-tubulin N-acetyltransferase 1 (Atat1), promotes the recruitment and processivity of molecular motors along MT tracks. However, the mechanism that controls Atat1 activity remains poorly understood. Here, we show that ATP-citrate lyase (Acly) is enriched in vesicles and provide Acetyl-Coenzyme-A (Acetyl-CoA) to Atat1. In addition, we showed that Acly expression is reduced upon loss of Elongator activity, further connecting Elongator to Atat1 in a pathway regulating α-tubulin acetylation and MT-dependent transport in projection neurons, across species. Remarkably, comparable defects occur in fibroblasts from Familial Dysautonomia (FD) patients bearing an autosomal recessive mutation in the gene coding for the Elongator subunit ELP1. Our data may thus shine light on the pathophysiological mechanisms underlying FD., (© 2021. The Author(s).)
- Published
- 2021
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12. Long- and short-ranged chiral interactions in DNA-assembled plasmonic chains.
- Author
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Martens K, Binkowski F, Nguyen L, Hu L, Govorov AO, Burger S, and Liedl T
- Subjects
- DNA genetics, DNA ultrastructure, Metal Nanoparticles chemistry, Metal Nanoparticles ultrastructure, Microscopy, Electron, Transmission, Nanostructures chemistry, Nanostructures ultrastructure, Stereoisomerism, Circular Dichroism methods, DNA chemistry, Gold chemistry, Nanotubes chemistry
- Abstract
Circular dichroism (CD) has long been used to trace chiral molecular states and changes of protein configurations. In recent years, chiral plasmonic nanostructures have shown potential for applications ranging from pathogen sensing to novel optical materials. The plasmonic coupling of the individual elements of such metallic structures is a crucial prerequisite to obtain sizeable CD signals. We here identify and implement various coupling entities-chiral and achiral-to demonstrate chiral transfer over distances close to 100 nm. The coupling is realized by an achiral nanosphere situated between a pair of gold nanorods that are arranged far apart but in a chiral fashion using DNA origami. The transmitter particle causes a strong enhancement of the CD response, the emergence of an additional chiral feature at the resonance frequency of the nanosphere, and a redshift of the longitudinal plasmonic resonance frequency of the nanorods. Matching numerical simulations elucidate the intricate chiral optical fields in complex architectures.
- Published
- 2021
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13. Recent African strains of Zika virus display higher transmissibility and fetal pathogenicity than Asian strains.
- Author
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Aubry F, Jacobs S, Darmuzey M, Lequime S, Delang L, Fontaine A, Jupatanakul N, Miot EF, Dabo S, Manet C, Montagutelli X, Baidaliuk A, Gámbaro F, Simon-Lorière E, Gilsoul M, Romero-Vivas CM, Cao-Lormeau VM, Jarman RG, Diagne CT, Faye O, Faye O, Sall AA, Neyts J, Nguyen L, Kaptein SJF, and Lambrechts L
- Subjects
- Aedes physiology, Aedes virology, Africa, Animals, Asia, Female, Humans, Male, Mice, Phylogeny, Virulence, Zika Virus classification, Zika Virus genetics, Zika Virus Infection transmission, Zika Virus pathogenicity, Zika Virus physiology, Zika Virus Infection mortality, Zika Virus Infection virology
- Abstract
The global emergence of Zika virus (ZIKV) revealed the unprecedented ability for a mosquito-borne virus to cause congenital birth defects. A puzzling aspect of ZIKV emergence is that all human outbreaks and birth defects to date have been exclusively associated with the Asian ZIKV lineage, despite a growing body of laboratory evidence pointing towards higher transmissibility and pathogenicity of the African ZIKV lineage. Whether this apparent paradox reflects the use of relatively old African ZIKV strains in most laboratory studies is unclear. Here, we experimentally compare seven low-passage ZIKV strains representing the recently circulating viral genetic diversity. We find that recent African ZIKV strains display higher transmissibility in mosquitoes and higher lethality in both adult and fetal mice than their Asian counterparts. We emphasize the high epidemic potential of African ZIKV strains and suggest that they could more easily go unnoticed by public health surveillance systems than Asian strains due to their propensity to cause fetal loss rather than birth defects.
- Published
- 2021
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14. Pan-cancer landscape of homologous recombination deficiency.
- Author
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Nguyen L, W M Martens J, Van Hoeck A, and Cuppen E
- Subjects
- Alleles, Breast Neoplasms diagnosis, DNA-Binding Proteins genetics, Databases, Genetic, Fanconi Anemia Complementation Group N Protein genetics, Female, Humans, Incidence, Loss of Heterozygosity, Male, Multigene Family, Mutation, Ovarian Neoplasms diagnosis, Pancreatic Neoplasms diagnosis, Pancreatic Neoplasms genetics, Prostatic Neoplasms diagnosis, Prostatic Neoplasms genetics, BRCA1 Protein genetics, BRCA2 Protein genetics, Breast Neoplasms genetics, Genomics methods, Homologous Recombination, Ovarian Neoplasms genetics
- Abstract
Homologous recombination deficiency (HRD) results in impaired double strand break repair and is a frequent driver of tumorigenesis. Here, we develop a genome-wide mutational scar-based pan-cancer Classifier of HOmologous Recombination Deficiency (CHORD) that can discriminate BRCA1- and BRCA2-subtypes. Analysis of a metastatic (n = 3,504) and primary (n = 1,854) pan-cancer cohort reveals that HRD is most frequent in ovarian and breast cancer, followed by pancreatic and prostate cancer. We identify biallelic inactivation of BRCA1, BRCA2, RAD51C or PALB2 as the most common genetic cause of HRD, with RAD51C and PALB2 inactivation resulting in BRCA2-type HRD. We find that while the specific genetic cause of HRD is cancer type specific, biallelic inactivation is predominantly associated with loss-of-heterozygosity (LOH), with increased contribution of deep deletions in prostate cancer. Our results demonstrate the value of pan-cancer genomics-based HRD testing and its potential diagnostic value for patient stratification towards treatment with e.g. poly ADP-ribose polymerase inhibitors (PARPi).
- Published
- 2020
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15. Author Correction: Nuclei multiplexing with barcoded antibodies for single-nucleus genomics.
- Author
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Gaublomme JT, Li B, McCabe C, Knecht A, Yang Y, Drokhlyansky E, Van Wittenberghe N, Waldman J, Dionne D, Nguyen L, De Jager PL, Yeung B, Zhao X, Habib N, Rozenblatt-Rosen O, and Regev A
- Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
- Published
- 2020
- Full Text
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16. A versatile soluble siglec scaffold for sensitive and quantitative detection of glycan ligands.
- Author
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Rodrigues E, Jung J, Park H, Loo C, Soukhtehzari S, Kitova EN, Mozaneh F, Daskhan G, Schmidt EN, Aghanya V, Sarkar S, Streith L, St Laurent CD, Nguyen L, Julien JP, West LJ, Williams KC, Klassen JS, and Macauley MS
- Subjects
- Animals, Antigens, CD genetics, Antigens, CD metabolism, Breast Neoplasms metabolism, CHO Cells, Cricetulus, Female, HEK293 Cells, Humans, Immunoglobulin Fc Fragments genetics, Immunoglobulin Fc Fragments metabolism, Immunoglobulin G genetics, Immunoglobulin G metabolism, K562 Cells, Mass Spectrometry, Polysaccharides metabolism, Sialic Acid Binding Ig-like Lectin 3 metabolism, Sialic Acid Binding Immunoglobulin-like Lectins genetics, Sialic Acid Binding Immunoglobulin-like Lectins isolation & purification, Sialic Acids metabolism, Sialyltransferases genetics, Sialyltransferases metabolism, Spleen cytology, Spleen metabolism, Streptavidin metabolism, Polysaccharides analysis, Sialic Acid Binding Immunoglobulin-like Lectins chemistry, Sialic Acid Binding Immunoglobulin-like Lectins metabolism
- Abstract
Sialic acid-binding immunoglobulin-type lectins (Siglecs) are immunomodulatory receptors that are regulated by their glycan ligands. The connections between Siglecs and human disease motivate improved methods to detect Siglec ligands. Here, we describe a new versatile set of Siglec-Fc proteins for glycan ligand detection. Enhanced sensitivity and selectivity are enabled through multimerization and avoiding Fc receptors, respectively. Using these Siglec-Fc proteins, Siglec ligands are systematically profiled on healthy and cancerous cells and tissues, revealing many unique patterns. Additional features enable the production of small, homogenous Siglec fragments and development of a quantitative ligand-binding mass spectrometry assay. Using this assay, the ligand specificities of several Siglecs are clarified. For CD33 (Siglec-3), we demonstrate that it recognizes both α2-3 and α2-6 sialosides in solution and on cells, which has implications for its link to Alzheimer's disease susceptibility. These soluble Siglecs reveal the abundance of their glycan ligands on host cells as self-associated molecular patterns.
- Published
- 2020
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17. Spatial domain analysis predicts risk of colorectal cancer recurrence and infers associated tumor microenvironment networks.
- Author
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Uttam S, Stern AM, Sevinsky CJ, Furman S, Pullara F, Spagnolo D, Nguyen L, Gough A, Ginty F, Lansing Taylor D, and Chakra Chennubhotla S
- Subjects
- Biomarkers metabolism, Fluorescent Antibody Technique, Gene Expression Regulation, Neoplastic genetics, Humans, Oligonucleotide Array Sequence Analysis, Precision Medicine, Systems Biology, Tumor Microenvironment genetics, Colorectal Neoplasms genetics, Neoplasm Recurrence, Local genetics
- Abstract
An unmet clinical need in solid tumor cancers is the ability to harness the intrinsic spatial information in primary tumors that can be exploited to optimize prognostics, diagnostics and therapeutic strategies for precision medicine. Here, we develop a transformational spatial analytics computational and systems biology platform (SpAn) that predicts clinical outcomes and captures emergent spatial biology that can potentially inform therapeutic strategies. We apply SpAn to primary tumor tissue samples from a cohort of 432 chemo-naïve colorectal cancer (CRC) patients iteratively labeled with a highly multiplexed (hyperplexed) panel of 55 fluorescently tagged antibodies. We show that SpAn predicts the 5-year risk of CRC recurrence with a mean AUROC of 88.5% (SE of 0.1%), significantly better than current state-of-the-art methods. Additionally, SpAn infers the emergent network biology of tumor microenvironment spatial domains revealing a spatially-mediated role of CRC consensus molecular subtype features with the potential to inform precision medicine.
- Published
- 2020
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18. Nuclei multiplexing with barcoded antibodies for single-nucleus genomics.
- Author
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Gaublomme JT, Li B, McCabe C, Knecht A, Yang Y, Drokhlyansky E, Van Wittenberghe N, Waldman J, Dionne D, Nguyen L, De Jager PL, Yeung B, Zhao X, Habib N, Rozenblatt-Rosen O, and Regev A
- Subjects
- Aged, Aged, 80 and over, Animals, Cell Nucleus chemistry, Cell Nucleus metabolism, DNA genetics, Female, Humans, Male, Mice, Mice, Inbred C57BL, Neurons chemistry, Neurons cytology, Neurons metabolism, Prefrontal Cortex chemistry, Prefrontal Cortex metabolism, RNA, Messenger genetics, RNA, Messenger metabolism, Antibodies analysis, Cell Nucleus genetics, Genomics methods, Single-Cell Analysis methods
- Abstract
Single-nucleus RNA-seq (snRNA-seq) enables the interrogation of cellular states in complex tissues that are challenging to dissociate or are frozen, and opens the way to human genetics studies, clinical trials, and precise cell atlases of large organs. However, such applications are currently limited by batch effects, processing, and costs. Here, we present an approach for multiplexing snRNA-seq, using sample-barcoded antibodies to uniquely label nuclei from distinct samples. Comparing human brain cortex samples profiled with or without hashing antibodies, we demonstrate that nucleus hashing does not significantly alter recovered profiles. We develop DemuxEM, a computational tool that detects inter-sample multiplets and assigns singlets to their sample of origin, and validate its accuracy using sex-specific gene expression, species-mixing and natural genetic variation. Our approach will facilitate tissue atlases of isogenic model organisms or from multiple biopsies or longitudinal samples of one donor, and large-scale perturbation screens.
- Published
- 2019
- Full Text
- View/download PDF
19. Neuroinspired unsupervised learning and pruning with subquantum CBRAM arrays.
- Author
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Shi Y, Nguyen L, Oh S, Liu X, Koushan F, Jameson JR, and Kuzum D
- Abstract
Resistive RAM crossbar arrays offer an attractive solution to minimize off-chip data transfer and parallelize on-chip computations for neural networks. Here, we report a hardware/software co-design approach based on low energy subquantum conductive bridging RAM (CBRAM®) devices and a network pruning technique to reduce network level energy consumption. First, we demonstrate low energy subquantum CBRAM devices exhibiting gradual switching characteristics important for implementing weight updates in hardware during unsupervised learning. Then we develop a network pruning algorithm that can be employed during training, different from previous network pruning approaches applied for inference only. Using a 512 kbit subquantum CBRAM array, we experimentally demonstrate high recognition accuracy on the MNIST dataset for digital implementation of unsupervised learning. Our hardware/software co-design approach can pave the way towards resistive memory based neuro-inspired systems that can autonomously learn and process information in power-limited settings.
- Published
- 2018
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- View/download PDF
20. Single rhodium atoms anchored in micropores for efficient transformation of methane under mild conditions.
- Author
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Tang Y, Li Y, Fung V, Jiang DE, Huang W, Zhang S, Iwasawa Y, Sakata T, Nguyen L, Zhang X, Frenkel AI, and Tao FF
- Abstract
Catalytic transformation of CH
4 under a mild condition is significant for efficient utilization of shale gas under the circumstance of switching raw materials of chemical industries to shale gas. Here, we report the transformation of CH4 to acetic acid and methanol through coupling of CH4 , CO and O2 on single-site Rh1 O5 anchored in microporous aluminosilicates in solution at ≤150 °C. The activity of these singly dispersed precious metal sites for production of organic oxygenates can reach about 0.10 acetic acid molecules on a Rh1 O5 site per second at 150 °C with a selectivity of ~70% for production of acetic acid. It is higher than the activity of free Rh cations by >1000 times. Computational studies suggest that the first C-H bond of CH4 is activated by Rh1 O5 anchored on the wall of micropores of ZSM-5; the formed CH3 then couples with CO and OH, to produce acetic acid over a low activation barrier.- Published
- 2018
- Full Text
- View/download PDF
21. Catalysis on singly dispersed bimetallic sites.
- Author
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Zhang S, Nguyen L, Liang JX, Shan J, Liu JJ, Frenkel AI, Patlolla A, Huang W, Li J, and Tao FF
- Abstract
A catalytic site typically consists of one or more atoms of a catalyst surface that arrange into a configuration offering a specific electronic structure for adsorbing or dissociating reactant molecules. The catalytic activity of adjacent bimetallic sites of metallic nanoparticles has been studied previously. An isolated bimetallic site supported on a non-metallic surface could exhibit a distinctly different catalytic performance owing to the cationic state of the singly dispersed bimetallic site and the minimized choices of binding configurations of a reactant molecule compared with continuously packed bimetallic sites. Here we report that isolated Rh1Co3 bimetallic sites exhibit a distinctly different catalytic performance in reduction of nitric oxide with carbon monoxide at low temperature, resulting from strong adsorption of two nitric oxide molecules and a nitrous oxide intermediate on Rh1Co3 sites and following a low-barrier pathway dissociation to dinitrogen and an oxygen atom. This observation suggests a method to develop catalysts with high selectivity.
- Published
- 2015
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- View/download PDF
22. Understanding complete oxidation of methane on spinel oxides at a molecular level.
- Author
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Tao FF, Shan JJ, Nguyen L, Wang Z, Zhang S, Zhang L, Wu Z, Huang W, Zeng S, and Hu P
- Abstract
It is crucial to develop a catalyst made of earth-abundant elements highly active for a complete oxidation of methane at a relatively low temperature. NiCo2O4 consisting of earth-abundant elements which can completely oxidize methane in the temperature range of 350-550 °C. Being a cost-effective catalyst, NiCo2O4 exhibits activity higher than precious-metal-based catalysts. Here we report that the higher catalytic activity at the relatively low temperature results from the integration of nickel cations, cobalt cations and surface lattice oxygen atoms/oxygen vacancies at the atomic scale. In situ studies of complete oxidation of methane on NiCo2O4 and theoretical simulations show that methane dissociates to methyl on nickel cations and then couple with surface lattice oxygen atoms to form -CH3O with a following dehydrogenation to -CH2O; a following oxidative dehydrogenation forms CHO; CHO is transformed to product molecules through two different sub-pathways including dehydrogenation of OCHO and CO oxidation.
- Published
- 2015
- Full Text
- View/download PDF
23. Cochlear supporting cell transdifferentiation and integration into hair cell layers by inhibition of ephrin-B2 signalling.
- Author
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Defourny J, Mateo Sánchez S, Schoonaert L, Robberecht W, Davy A, Nguyen L, and Malgrange B
- Subjects
- Animals, Cochlea metabolism, Ephrin-B2 antagonists & inhibitors, Hair Cells, Auditory, Mice, Cell Transdifferentiation, Cochlea embryology, Ephrin-B2 metabolism
- Abstract
In mammals, cochlear sensory hair cells that are responsible for hearing are postmitotic and are not replaced after loss. One of the most promising strategies to regenerate hair cells is to identify and inhibit the factors preventing the conversion of adjacent non-sensory supporting cells into hair cells. Here we demonstrate that mammalian hair cells can be directly generated from supporting cells by inhibition of ephrin-B2 signalling. Using either ephrin-B2 conditional knockout mice, shRNA-mediated gene silencing or soluble inhibitors, we found that downregulation of ephrin-B2 signalling at embryonic stages results in supporting cell translocation into hair cell layers and subsequent switch in cell identity from supporting cell to hair cell fate. As transdifferentiation is here a result of displacement across boundary, this original finding presents the interest that newly generated hair cells directly integrate either hair cell layer, then would be likely more rapidly able to fit into functional circuitry.
- Published
- 2015
- Full Text
- View/download PDF
24. Ephrin-A5/EphA4 signalling controls specific afferent targeting to cochlear hair cells.
- Author
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Defourny J, Poirrier AL, Lallemend F, Mateo Sánchez S, Neef J, Vanderhaeghen P, Soriano E, Peuckert C, Kullander K, Fritzsch B, Nguyen L, Moonen G, Moser T, and Malgrange B
- Subjects
- Animals, Auditory Threshold, Ephrin-A5 deficiency, Ephrin-A5 genetics, Gene Expression Regulation, Growth Cones metabolism, Immunohistochemistry, Mice, Microscopy, Confocal, Models, Biological, Receptor, EphA4 genetics, Spiral Ganglion cytology, Spiral Ganglion innervation, Spiral Ganglion metabolism, Synaptic Transmission, Afferent Pathways metabolism, Ephrin-A5 metabolism, Hair Cells, Auditory, Inner metabolism, Receptor, EphA4 metabolism, Signal Transduction
- Abstract
Hearing requires an optimal afferent innervation of sensory hair cells by spiral ganglion neurons in the cochlea. Here we report that complementary expression of ephrin-A5 in hair cells and EphA4 receptor among spiral ganglion neuron populations controls the targeting of type I and type II afferent fibres to inner and outer hair cells, respectively. In the absence of ephrin-A5 or EphA4 forward signalling, a subset of type I projections aberrantly overshoot the inner hair cell layer and invade the outer hair cell area. Lack of type I afferent synapses impairs neurotransmission from inner hair cells to the auditory nerve. By contrast, radial shift of type I projections coincides with a gain of presynaptic ribbons that could enhance the afferent signalling from outer hair cells. Ephexin-1, cofilin and myosin light chain kinase act downstream of EphA4 to induce type I spiral ganglion neuron growth cone collapse. Our findings constitute the first identification of an Eph/ephrin-mediated mutual repulsion mechanism responsible for specific sorting of auditory projections in the cochlea.
- Published
- 2013
- Full Text
- View/download PDF
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