109 results on '"Christopher Ng"'
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2. Essays in Labor Economics
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Kevin Christopher Ng
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This dissertation is comprised of three essays, each examining a different topic in labor economics. In Chapter 1, I examine the productivity and selection effects of K-12 teacher tenure by leveraging variation from New Jersey's TEACHNJ Act. This law extended the pre-tenure period from three to four years and allowed districts to dismiss consistently low-performing teachers. I use multiple identification strategies to estimate the productivity effects of tenure across a teacher's career. I evaluate the productivity effects at tenure receipt using a difference-in-differences design, which compares fourth-year tenured and pre-tenured teachers. At tenure receipt, math value-added declines but English language arts value-added and summative ratings remain unchanged. To estimate the productivity effects later in the career, I use a regression discontinuity design relying on discontinuities in job security around summative rating thresholds. Later in the career, tenure has no impact on productivity. Thus, tenure induces a transitory decline in math value-added without impacting other dimensions of teacher performance. Focusing on the labor market effects, I compare teachers hired before and after TEACHNJ within the same district and experience level. The TEACHNJ Act disproportionately increased male and Black teacher turnover rates. TEACHNJ did not impact the quality of the teacher labor market as measured by value-added, though higher rated teachers often filled new vacancies. Since the TEACHNJ Act only relies on summative ratings to make personnel decisions, this result aligns with a multitask principal-agent model where only one of several measures of performance is used to evaluate the employee. In Chapter 2, I evaluate techniques to identify high-quality teachers. Since tenure restricts dismissals of experienced teachers, schools must predict productivity and dismiss those expected to perform ineffectively prior to tenure receipt. Many states solely rely on evaluation scores to guide these personnel decisions without considering other dimensions of teacher performance. For example, New Jersey uses summative ratings, which primarily rely on supervisor evaluations. I use various predictive models to rank teachers based on predicted value-added and summative ratings. I then simulate revised personnel decisions and test for changes in average retained teacher performance. In this exercise, I adjust two factors that impact the quality of the predictions: the number of predictors and the length of the pre-tenure period. Both factors impact the precision of the predictions, though extended pre-tenure periods also may negatively impact selection into teaching. I find that revised algorithms using both value-added and summative ratings increase the average value-added of retained teachers by 0.01 standard deviations without decreasing summative ratings or diversity. This Pareto improvement equates to a present value gain of $2,240 per student. These returns are a product of using additional information rather than advanced algorithms, as I generate similar gains when using simple ordinary least squares regressions or advanced machine learning techniques. In comparison, algorithms that extend the pre-tenure period beyond one year do not provide enough additional information to significantly improve average retained teacher performance unless dismissal rates increase dramatically. In Chapter 3, my coauthor and I examine how returns to enrolling in science, technology, engineering, and mathematics (STEM) programs vary with students' academic preparation. We match data on STEM admissions at a Colombian flagship university to nationwide college and earnings records. Our identification strategy combines a regression discontinuity design with variation in admission quotas. We find that less-prepared students were less likely to complete a STEM degree than their more able peers, but they had larger earnings returns to enrolling. Our results suggest that policies that encourage less-prepared students to enroll in STEM programs can yield large but unevenly distributed earnings gains. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]
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- 2022
3. Accelerating DNNs inference with predictive layer fusion.
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MohammadHossein Olyaiy, Christopher Ng, and Mieszko Lis
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- 2021
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4. Deterministic Atomic Buffering.
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Yuan-Hsi Chou, Christopher Ng, Shaylin Cattell, Jeremy Intan, Matthew D. Sinclair, Joseph Devietti, Timothy G. Rogers, and Tor M. Aamodt
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- 2020
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5. Preleukemic and second-hit mutational events in an acute myeloid leukemia patient with a novel germline RUNX1 mutation
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Isaac KS Ng, Joanne Lee, Christopher Ng, Bustamin Kosmo, Lily Chiu, Elaine Seah, Michelle Meng Huang Mok, Karen Tan, Motomi Osato, Wee-Joo Chng, Benedict Yan, and Lip Kun Tan
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Familial platelet disorder ,Acute myeloid Leukaemia ,RUNX1 ,Stem cell transplant ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Abstract Background Germline mutations in the RUNX1 transcription factor give rise to a rare autosomal dominant genetic condition classified under the entity: Familial Platelet Disorders with predisposition to Acute Myeloid Leukaemia (FPD/AML). While several studies have identified a myriad of germline RUNX1 mutations implicated in this disorder, second-hit mutational events are necessary for patients with hereditary thrombocytopenia to develop full-blown AML. The molecular picture behind this process remains unclear. We describe a patient of Malay descent with an unreported 7-bp germline RUNX1 frameshift deletion, who developed second-hit mutations that could have brought about the leukaemic transformation from a pre-leukaemic state. These mutations were charted through the course of the treatment and stem cell transplant, showing a clear correlation between her clinical presentation and the mutations present. Case presentation The patient was a 27-year-old Malay woman who presented with AML on the background of hereditary thrombocytopenia affecting her father and 3 brothers. Initial molecular testing revealed the same novel RUNX1 mutation in all 5 individuals. The patient received standard induction, consolidation chemotherapy, and a haploidentical stem cell transplant from her mother with normal RUNX1 profile. Comprehensive genomic analyses were performed at diagnosis, post-chemotherapy and post-transplant. A total of 8 mutations (RUNX1, GATA2, DNMT3A, BCORL1, BCOR, 2 PHF6 and CDKN2A) were identified in the pre-induction sample, of which 5 remained (RUNX1, DNMT3A, BCORL1, BCOR and 1 out of 2 PHF6) in the post-treatment sample and none were present post-transplant. In brief, the 3 mutations which were lost along with the leukemic cells at complete morphological remission were most likely acquired leukemic driver mutations that were responsible for the AML transformation from a pre-leukemic germline RUNX1-mutated state. On the contrary, the 5 mutations that persisted post-treatment, including the germline RUNX1 mutation, were likely to be part of the preleukemic clone. Conclusion Further studies are necessary to assess the prevalence of these preleukemic and secondary mutations in the larger FPD/AML patient cohort and establish their prognostic significance. Given the molecular heterogeneity of FPD/AML and other AML subtypes, a better understanding of mutational classes and their involvement in AML pathogenesis can improve risk stratification of patients for more effective and targeted therapy.
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- 2018
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6. Analyzing Machine Learning Workloads Using a Detailed GPU Simulator.
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Jonathan S. Lew, Deval A. Shah, Suchita Pati, Shaylin Cattell, Mengchi Zhang, Amruth Sandhupatla, Christopher Ng, Negar Goli, Matthew D. Sinclair, Timothy G. Rogers, and Tor M. Aamodt
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- 2019
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7. Treatment outcomes among rural and urban patients with obstructive sleep apnea: a prospective cohort study
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Willis H. Tsai, Cheryl R. Laratta, Imhokhai Ogah, Ada Ip-Buting, Heather Sharpe, Sachin R. Pendharkar, Peter Peller, Christopher Ng, and Jennifer Corrigan
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Rural Population ,Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,medicine.medical_treatment ,Treatment outcome ,Patient satisfaction ,medicine ,Humans ,Continuous positive airway pressure ,Prospective cohort study ,Sleep Apnea, Obstructive ,Continuous Positive Airway Pressure ,business.industry ,Epworth Sleepiness Scale ,Rural health ,medicine.disease ,Scientific Investigations ,nervous system diseases ,respiratory tract diseases ,Obstructive sleep apnea ,Neurology ,Emergency medicine ,Patient Compliance ,Residence ,Neurology (clinical) ,business - Abstract
STUDY OBJECTIVES: To determine whether adherence to continuous positive airway pressure (CPAP) in adults with uncomplicated obstructive sleep apnea differs by rural vs urban residential address. METHODS: In this prospective cohort study, we recruited adults who initiated CPAP for uncomplicated obstructive sleep apnea that was diagnosed by a physician using sleep specialist-interpreted diagnostic testing. Participants were classified as urban (community size > 100,000) or rural (community size < 100,000) by translating residential postal code into geographic census area. The primary outcome was mean daily hours of CPAP use compared between rural and urban patients. Secondary outcomes included the proportion of patients who were adherent to CPAP, change in Epworth Sleepiness Scale score, change in EuroQOL-5D visual analog score, and Visit-Specific Satisfaction Instrument score. All outcomes were measured 3 months after CPAP initiation. RESULTS: We enrolled 242 patients (100 rural) with a mean (standard deviation) age of 51 (13) years and a respiratory event index of 24 (18) events/h. The mean (95% confidence interval) CPAP use was 3.19 (2.8–3.58) hours/night and 35% were CPAP-adherent, with no difference between urban and rural patients. Among the 65% of patients who were using CPAP at 3 months, the mean CPAP use was 4.89 (4.51–5.28) hours/night and was not different between rural and urban patients. Improvement in the Epworth Sleepiness Scale score and patient satisfaction was similar between groups, but the EuroQOL-5D score improved to a greater extent in rural patients. Urban or rural residence was not associated with CPAP adherence according to multivariable regression analysis. CONCLUSIONS: Rural vs urban residence was not associated with differences in CPAP adherence among patients with uncomplicated OSA diagnosed by a physician using specialist-interpreted sleep diagnostic testing. CITATION: Corrigan J, Tsai WH, Ip-Buting A, et al. Treatment outcomes among rural and urban patients with obstructive sleep apnea: a prospective cohort study. J Clin Sleep Med. 2022;18(4):1013–1020.
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- 2022
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8. Supplementary Figure Legends from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure Legends
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- 2023
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9. Supplementary Figure 7 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 7. INPP4B loss does not produce any morphological or cytoskeletal differences.
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- 2023
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10. Supplementary Figure 3 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 14407K, Supporting histology for Olaparib treatment in vivo.
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- 2023
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11. Supplementary Figure 3 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 3. INPP4B's promoter is not directly methylated.
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- 2023
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12. Supplementary Figure S3 from Suppression of CHK1 by ETS Family Members Promotes DNA Damage Response Bypass and Tumorigenesis
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Pier Paolo Pandolfi, Sabina Signoretti, Carlos Cordon-Cardo, Mireia Castillo-Martin, Rodolfo Montironi, Laura Poliseno, Caterina Nardella, Alice H. Berger, Christopher Ng, Valentina Quarantotti, Robin M. Hobbs, Brett S. Carver, Tomoki Ishikawa, Nina Seitzer, Ugo Ala, Jlenia Guarnerio, Riccardo Taulli, Ming Chen, Shohreh Varmeh, and Andrea Lunardi
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Supplementary Figure S3. ERG binding to CHK1 promoter.
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- 2023
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13. Supplementary Figure 5 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 632K, Preclinical assessment of Olaparib and BKM120 treatment in vivo.
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- 2023
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14. Supplementary Figure Legends from Suppression of CHK1 by ETS Family Members Promotes DNA Damage Response Bypass and Tumorigenesis
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Pier Paolo Pandolfi, Sabina Signoretti, Carlos Cordon-Cardo, Mireia Castillo-Martin, Rodolfo Montironi, Laura Poliseno, Caterina Nardella, Alice H. Berger, Christopher Ng, Valentina Quarantotti, Robin M. Hobbs, Brett S. Carver, Tomoki Ishikawa, Nina Seitzer, Ugo Ala, Jlenia Guarnerio, Riccardo Taulli, Ming Chen, Shohreh Varmeh, and Andrea Lunardi
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Supplementary Figure Legends
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- 2023
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15. Supplementary Figure 1 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 546K, Olaparib induces a differing response in vitro depending on the genetic background.
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- 2023
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16. Supplementary Figure 2 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 2951K, Olaparib induces a differing response in vivo depending on the genetic background.
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- 2023
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17. Supplementary Figure 2 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 2. Validation of INPP4B antibody.
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- 2023
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18. Supplementary Figure 1 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 1. Generation of Pten+/-Inpp4b+/- and Pten+/-Inpp4b-/- mice.
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- 2023
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19. Supplementary Figure 4 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 114k, Supporting western blot analysis and drug treatment in prostate cancer cell lines.
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- 2023
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20. Supplementary Materials and Methods, Figure Legends from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 116K, Supplementary Materials and Methods and Supplementary Figure Legends.
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- 2023
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21. Supplementary Figure 4 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 4. Loss of Inpp4b in MEFs lead to increased Akt activation.
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- 2023
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22. Supplementary Figure 5 from In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K–AKT Signaling at Endosomes
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Pier Paolo Pandolfi, Emilio Hirsch, Roderick T. Bronson, Takehiko Sasaki, Junko Sasaki, John G. Clohessy, Jacqueline Fung, Christopher Ng, Antonella Papa, Michiya Nishino, Leonardo Salmena, Ming Chen, Daniel T. Ruan, Federico Gulluni, Andrea Lunardi, and Chen Li Chew
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Supplementary Figure 5. Loss of INPP4B results in increased AKT2 activation.
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- 2023
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23. Supplementary Figure 7 from Vulnerabilities of PTEN–TP53-Deficient Prostate Cancers to Compound PARP–PI3K Inhibition
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Pier Paolo Pandolfi, Lewis C. Cantley, John G. Clohessy, Caterina Nardella, John M. Asara, Massimo Loda, Sabina Signoretti, Kaitlyn A. Webster, Christopher Ng, Andrea Lunardi, Ming Chen, Robin M. Hobbs, Antonella Papa, Mirjam T. Epping, Xue-Song Liu, Akash Patnaik, Min Sup Song, Su Jung Song, Nina Seitzer, and Enrique González-Billalabeitia
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PDF - 138K, Survival curves of the in vivo treatment of Olaparib and BKM120.
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- 2023
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24. Supplementary Methods, Figure Legends, Figures S1 - S7, Table S1 - Supplementary Figure S1 from The APC/C E3 Ligase Complex Activator FZR1 Restricts BRAF Oncogenic Function
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Wenyi Wei, Pier Paolo Pandolfi, Rutao Cui, Marc W. Kirschner, Roderick T. Bronson, Lian Xue, Min Sup Song, Pengda Liu, Christopher Ng, Jacqueline Fung, Kelsey Berry, Jesse M. Katon, Hiroyuki Inuzuka, Jing Liu, Ying Lu, Su-Jung Song, Jinfang Zhang, Qing Yin, Xiangpeng Dai, Juxiang Cao, Ming Chen, and Lixin Wan
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Depletion of FZR1 leads to BRAF stabilization and subsequent ERK activation. Supplementary Figure S2. Depletion of FZR1 triggers the onset of premature senescence in primary melanocytes. Supplementary Figure S3. APCFZR1 promotes BRAF ubiquitination and subsequent degradation in a D-box dependent manner. Supplementary Figure S4. FZR1 disrupts the BRAF dimerization process. Supplementary Figure S5. Phosphorylation of FZR1 N-terminus by ERK and CYCLIN D1/CDK4 inhibits the APCFZR1 E3 ubiquitin ligase activity. Supplementary Figure S6. Pharmacologically inhibiting BRAF/ERK and CDK4 restores the APCFZR1 E3 ligase activity. Supplementary Figure S7. Depletion of FZR1 co-operates with PTEN deficiency to promote co-activation of BRAF/ERK and AKT oncogenic signaling both in vitro and in vivo. Supplementary Table S1. Mutation and deletion of FZR1 and 14 APC core complex subunits identified in melanoma patients from the TCGA melanoma dataset (cbioportal.org).
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- 2023
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25. Analyzing Machine Learning Workloads Using a Detailed GPU Simulator.
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Jonathan S. Lew, Deval Shah, Suchita Pati, Shaylin Cattell, Mengchi Zhang, Amruth Sandhupatla, Christopher Ng, Negar Goli, Matthew D. Sinclair, Timothy G. Rogers, and Tor M. Aamodt
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- 2018
26. Who makes what sound?: supporting real-time musical improvisations of electroacoustic ensembles.
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Tim Robert Merritt, Weiman Kow, Christopher Ng, Kevin McGee, and Lonce Wyse
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- 2010
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27. Congenital subcostal hernia in a patient with Lumbo-Costovertebral Syndrome, case report and review of the literature
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Colin Muncie, Christopher Ng, Henry Giles, and Christopher Blewett
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Congenital ,Subcostal hernia ,lumbo-costovertebral ,Pediatrics ,RJ1-570 ,Surgery ,RD1-811 - Abstract
Congenital subcostal hernias are a very rare type of flank hernia. They are typically asymptomatic but are more difficult to fix as the child grows, warranting early repair. They are typically found in the setting of multiple congenital anomalies. We report a congenital subcostal hernia associated with Lumbo-Costovertebral Syndrome, which is already known to be associated with congenital lumbar hernias. We will report the background and outcome of primary repair in such a hernia.
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- 2016
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28. PAF-Mediated MAPK Signaling Hyperactivation via LAMTOR3 Induces Pancreatic Tumorigenesis
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Sohee Jun, Sunhye Lee, Han-Cheon Kim, Christopher Ng, Andrea M. Schneider, Hong Ji, Haoqiang Ying, Huamin Wang, Ronald A. DePinho, and Jae-Il Park
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Biology (General) ,QH301-705.5 - Abstract
Deregulation of mitogen-activated protein kinase (MAPK) signaling leads to development of pancreatic cancer. Although Ras-mutation-driven pancreatic tumorigenesis is well understood, the underlying mechanism of Ras-independent MAPK hyperactivation remains elusive. Here, we have identified a distinct function of PCNA-associated factor (PAF) in modulating MAPK signaling. PAF is overexpressed in pancreatic cancer and required for pancreatic cancer cell proliferation. In mouse models, PAF expression induced pancreatic intraepithelial neoplasia with expression of pancreatic cancer stem cell markers. PAF-induced ductal epithelial cell hyperproliferation was accompanied by extracellular signal-regulated kinase (ERK) phosphorylation independently of Ras or Raf mutations. Intriguingly, PAF transcriptionally activated the expression of late endosomal/lysosomal adaptor, MAPK and mTOR activator 3 (LAMTOR3), which hyperphosphorylates MEK and ERK and is necessary for pancreatic cancer cell proliferation. Our results reveal an unsuspected mechanism of mitogenic signaling activation via LAMTOR3 and suggest that PAF-induced MAPK hyperactivation contributes to pancreatic tumorigenesis.
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- 2013
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29. Krüppel-like Factor 5 Promotes Sonic Hedgehog Signaling and Neoplasia in Barrett's Esophagus and Esophageal Adenocarcinoma
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Christopher Ng, John W. Harmon, Yulan Cheng, Stephen J. Meltzer, Ke Ma, and Tomoharu Miyashita
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0301 basic medicine ,Original article ,Cancer Research ,Gene knockdown ,biology ,Cellular differentiation ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,medicine.disease ,lcsh:RC254-282 ,Intestinal epithelium ,Hedgehog signaling pathway ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Oncology ,Cell culture ,030220 oncology & carcinogenesis ,Barrett's esophagus ,Cancer research ,medicine ,biology.protein ,Sonic hedgehog ,Transcription factor - Abstract
Krüppel-like Factor 5 (KLF5) is a zinc-finger transcription factor associated with cell cycle progression and cell survival. KLF5 plays a key role in mammalian intestinal epithelium development and maintenance, expressed at high levels in basal proliferating cells and low levels in terminally differentiated cells. Considering Barrett's esophagus (BE) and esophageal adenocarcinoma's (EAC) histopathological similarities to intestinal epithelium, we sought to determine KLF5’s role in BE and EAC, as well as KLF5’s possible connection to the sonic hedgehog (SHH) pathway which is highly active in BE and EAC development. Low levels of KLF5 mRNA were found in BE cell lines and tissue– similar to what has been reported in differentiated intestinal epithelium. In contrast, higher KLF5 levels were observed in EAC cells and tissues. KLF5 knockdown in EAC cells caused significant decreases in cell migration, proliferation, and EAC-associated gene expression. Moreover, KLF5 knockdown led to decreased SHH signaling. These results suggest that KLF5 is connected to the SHH pathway in BE and EAC and may represent a potential drug target in EAC; further studies are now indicated to verify these findings and elucidate underlying mechanisms involved.
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- 2019
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30. Targeting the Hedgehog Pathway Using Itraconazole to Prevent Progression of Barrett's Esophagus to Invasive Esophageal Adenocarcinoma
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Tomoharu Miyashita, Marianna Zahurak, Christine H. Chung, Guy P. Marti, Stephen J. Meltzer, Amir Mehdi Ansari, Aerielle E. Matsangos, Ken Ichi Mukaisho, Marcia Irene Canto, Anne Heloise Stricker-Krongrad, A. Karim Ahmed, Michelle A. Rudek, Maryam Kherad Pezhouh, Ronan J. Kelly, Louis J. Born, Kevan J. Salimian, Frank Lay, Christopher Ng, and John W. Harmon
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Male ,medicine.medical_specialty ,Indian hedgehog ,Esophageal Neoplasms ,Itraconazole ,Adenocarcinoma ,Gastroenterology ,Article ,Rats, Sprague-Dawley ,Barrett Esophagus ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Animals ,Hedgehog Proteins ,Neoplasm Invasiveness ,Esophagus ,Sonic hedgehog ,Hedgehog ,biology ,business.industry ,medicine.disease ,biology.organism_classification ,Hedgehog signaling pathway ,Rats ,Esophageal Tissue ,Disease Models, Animal ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Barrett's esophagus ,Disease Progression ,biology.protein ,030211 gastroenterology & hepatology ,Surgery ,business ,medicine.drug - Abstract
Objective The aim of the study was to investigate whether inhibition of Sonic Hedgehog (SHH) pathway would prevent progression of Barrett's Esophagus (BE) to esophageal adenocarcinoma. Background The hedgehog signaling pathway is a leading candidate as a molecular mediator of BE and esophageal adenocarcinoma (EAC). Repurposed use of existing off-patent, safe and tolerable drugs that can inhibit hedgehog, such as itraconazole, could prevent progression of BE to EAC. Methods The efficacy of itraconazole was investigated using a surgical rat reflux model of Barrett's Metaplasia (BM). Weekly intraperitoneal injections of saline (control group) or itraconazole (treatment group; 200 mg/kg) were started at 24 weeks postsurgery. Esophageal tissue was harvested at 40 weeks. The role of the Hh pathway was also evaluated clinically. Esophageal tissue was harvested after 40 weeks for pathological examination and evaluation of the SHH pathway by immunohistochemistry. Results BM was present in control animals 29 of 31 (93%) versus itraconazole 22 of 24 (91%). EAC was significantly lower in itraconazole 2 of 24 (8%) versus control 10 of 31 (32%), respectively (P = 0.033). Esophageal SHH levels were lower in itraconazole vs control (P = 0.12). In esophageal tissue from humans with recurrent or persistent dysplastic BE within 24 months of ablative treatment, strong SHH and Indian Hedgehog expression occurred in distal BE versus proximal squamous epithelium, odds ratio = 6.1 (95% confidence interval: 1.6, 23.4) and odds ratio = 6.4 (95% confidence interval: 1.2, 32.8), respectively. Conclusion Itraconazole significantly decreases EAC development and SHH expression in a preclinical animal model of BM. In humans, BE tissue expresses higher SHH, Indian Hedgehog, and bone morphogenic protein levels than normal squamous esophageal epithelium.
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- 2019
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31. Liver biopsy needle size and adequacy of sample: Review of practice at a children’s liver centre
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Nasim Tahir and Christopher Ng
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Radiology, Nuclear Medicine and imaging ,General Medicine - Published
- 2022
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32. Radical mastectomy of massive stage IV triple negative breast cancer to improve hygiene and comfort in a 90-year-old woman: a case report
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Christopher Ng, Richard C. Spinale, and Nicole C. Jameison
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medicine.medical_specialty ,Hygiene ,business.industry ,General surgery ,medicine.medical_treatment ,media_common.quotation_subject ,medicine ,Stage iv ,business ,Radical mastectomy ,Triple-negative breast cancer ,media_common - Published
- 2022
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33. A rare case of spontaneous otogenic pneumocephalus with pictorial illustration of temporal evolution
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Sivashankar Subramaniam and Justin Christopher Ng
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medicine.medical_specialty ,Neurology ,Ear, Middle ,Conservative Treatment ,03 medical and health sciences ,0302 clinical medicine ,Pneumocephalus ,Physiology (medical) ,Temporal bone ,medicine ,Humans ,Intracranial pressure ,Neuroradiology ,Aged ,business.industry ,General Medicine ,medicine.disease ,Temporal Lobe ,Skull ,medicine.anatomical_structure ,Otorhinolaryngology ,030220 oncology & carcinogenesis ,Surgery ,Female ,Neurology (clinical) ,Neurosurgery ,Radiology ,business ,Tomography, X-Ray Computed ,030217 neurology & neurosurgery ,Follow-Up Studies - Abstract
Pneumocephalus is commonly seen on imaging in the setting of craniofacial trauma, skull base tumours, intracranial infection and after neurological intervention. Spontaneous pneumocephalus in the absence of these conditions is exceedingly rare, with only approximately 30 cases reported in the literature to date. Spontaneous otogenic pneumocephalus (SOP) is believed to occur as a result of anomalous communication between the intracranial space and a hyper-pneumatised temporal bone, with either positive extra-to-intracranial pressure or negative intracranial pressure gradient. These anomalous communicating channels may only become clinically apparent when triggered by episodes of acute increase in middle ear pressure during coughing, sneezing, Valsalva manoeuvre or significant change in atmospheric pressure. Patients may exhibit a wide range of neurological symptoms and the aim of treatment is to reduce the risk of complications such as infection and intracranial hypertension. Both conservative and neurosurgical approaches have been described. We report a case of SOP in which the patient was conservatively managed, and spontaneous resolution of pneumocephalus was documented on serial computed tomography (CT) scans. This unique case clearly demonstrates the natural history and temporal evolution of SOP without surgical intervention. This knowledge may potentially obviate the need for surgery, thus reducing morbidity and mortality in patients who are poor surgical candidates.
- Published
- 2020
34. Deterministic Atomic Buffering
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Matthew D. Sinclair, Joseph Devietti, Yuan Hsi Chou, Christopher Ng, Timothy G. Rogers, Jeremy Intan, Tor M. Aamodt, and Shaylin Cattell
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010302 applied physics ,Computer science ,Serialization ,0103 physical sciences ,Atomic operations ,0202 electrical engineering, electronic engineering, information engineering ,02 engineering and technology ,Thread (computing) ,Parallel computing ,01 natural sciences ,Determinism ,020202 computer hardware & architecture ,Scheduling (computing) - Abstract
Deterministic execution for GPUs is a desirable property as it helps with debuggability and reproducibility. It is also important for safety regulations, as safety critical workloads are starting to be deployed onto GPUs. Prior deterministic architectures, such as GPUDet, attempt to provide strong determinism for all types of workloads, incurring significant performance overheads due to the many restrictions that are required to satisfy determinism. We observe that a class of reduction workloads, such as graph applications and neural architecture search for machine learning, do not require such severe restrictions to preserve determinism. This motivates the design of our system, Deterministic Atomic Buffering (DAB), which provides deterministic execution with low area and performance overheads by focusing solely on ordering atomic instructions instead of all memory instructions. By scheduling atomic instructions deterministically with atomic buffering, the results of atomic operations are isolated initially and made visible in the future in a deterministic order. This allows the GPU to execute deterministically in parallel without having to serialize its threads for atomic operations as opposed to GPUDet. Our simulation results show that, for atomic-intensive applications, DAB performs 4× better than GPUDet and incurs only a 23% slowdown on average compared to a non-deterministic GPU architecture. We also characterize the bottlenecks and provide insights for future optimizations.
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- 2020
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35. The Seismic Shift in End-of-Life Care: Palliative Care Challenges in the Era of Medical Assistance in Dying
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Anita Ho, Kim Jameson, Soodabeh Joolaee, and Christopher Ng
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Canada ,Terminal Care ,Palliative care ,Medical Assistance ,business.industry ,Palliative Care ,General Medicine ,Bioethics ,Suicide, Assisted ,Anesthesiology and Pain Medicine ,Hospice Care ,Nursing ,Medicine ,Humans ,business ,End-of-life care ,General Nursing ,Hospice care ,Qualitative research - Abstract
Background: Concerns regarding personal, professional, administrative, and institutional implications of medical assistance in dying (MAiD) are of particular interest to palliative and hospice care...
- Published
- 2020
36. CEBPA mutational analysis in acute myeloid leukaemia by a laboratory-developed next-generation sequencing assay
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Wee Joo Chng, Christopher Ng, Chun Kiat Lee, Kenneth Hon Kim Ban, Jingxue Guo, Jianbiao Zhou, Bustamin Kosmo, H. Lee, Karen Tan, Tin Wee Tan, Sherry Ho, Mingxuan Lin, Peak-Ling Lee, Zhaojin Chen, Benedict Yan, and Lily Chiu
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0301 basic medicine ,Genetics ,FASTQ format ,General Medicine ,Gold standard (test) ,Biology ,Amplicon ,DNA sequencing ,Pathology and Forensic Medicine ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Polymorphism (computer science) ,030220 oncology & carcinogenesis ,CEBPA ,Myeloid leukaemia ,GC-content - Abstract
AimThe presence of biallelic CEBPA mutations is a favourable prognostic feature in acute myeloid leukaemia (AML). CEBPA mutations are currently identified through conventional capillary sequencing (CCS). With the increasing adoption of next-generation sequencing (NGS) platforms, challenges with regard to amplification efficiency of CEBPA due to the high GC content may be encountered, potentially resulting in suboptimal coverage. Here, the performance of an amplicon-based NGS method using a laboratory-developed CEBPA-specific Nextera XT (CEBNX) was evaluated.MethodsMutational analyses of the CEBPA gene of 137 AML bone marrow or peripheral blood retrospective specimens were performed by the amplification of the CEBPA gene using the Expand Long Range dNTPack and the amplicons processed by CCS and NGS. CEBPA-specific libraries were then constructed using the Nextera XT V.2 kit. All FASTQ files were then processed with the MiSeq Reporter V.2.6.2.3 using the PCR Amplicon workflow via the customised CEBPA-specific manifest file. The variant calling format files were analysed using the Illumina Variant Studio V.2.2.ResultsA coverage per base of 3631X to 28184X was achieved. 22 samples (16.1%) were found to contain CEBPA mutations, with variant allele frequencies (VAF) ranging from 3.8% to 58.2%. Taking CCS as the ‘gold standard’, sensitivity and specificity of 97% and 97% was achieved. For the transactivation domain 2 polymorphism (c.584_589dupACCCGC/p.His195_Pro196dup), the CEBNX achieved 100% sensitivity and 100% specificity relative to CCS.ConclusionsOur laboratory-developed CEBNX workflow shows high coverage and thus overcomes the challenges associated with amplification efficiency and low coverage of CEBPA. Therefore, our assay is suitable for deployment in the clinical laboratory.
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- 2017
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37. Performance evaluation of Cepheid Xpert Norovirus kit with a user-modified protocol
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Evelyn Siew-Chuan Koay, Roland Jureen, Mun Han Leong, Rachel Shi-Lei Wong, Benedict Yan, Christopher Ng, Fion Yeo, Wai Theng Chia, Gabriel Yan, Kok-Siong Poon, Lily-Lily Chiu, H. Lee, and Chun Kiat Lee
- Subjects
Adult ,Male ,0301 basic medicine ,Adolescent ,Genotype ,Stool sample ,030106 microbiology ,Sample processing ,Cross Reactions ,Real-Time Polymerase Chain Reaction ,medicine.disease_cause ,Sensitivity and Specificity ,Feces ,Young Adult ,03 medical and health sciences ,fluids and secretions ,Virology ,Rotavirus ,Humans ,Medicine ,Child ,Aged ,Biological Specimen Banks ,Caliciviridae Infections ,Aged, 80 and over ,Clinical Laboratory Techniques ,business.industry ,Norovirus ,Infant ,Middle Aged ,Gastroenteritis ,Infectious Diseases ,Child, Preschool ,RNA, Viral ,Female ,Reagent Kits, Diagnostic ,business - Abstract
The Cepheid Xpert® Norovirus kit automates sample processing, nucleic acid extraction, and real-time reverse transcription polymerase chain reactions (RT-PCRs) to detect norovirus genogroups I (GI) and II (GII). Eighty-five stool samples collected between February 2015 and May 2017 were used to compare the performance of a user-modified Xpert assay against a clinically validated laboratory-developed test (LDT). Of the 85 samples, 54 were previously archived in -80°C freezer. The remaining 31 were fresh samples tested concurrently with the LDT. The results of all samples tested using the Xpert kit and LDT were found to be concordant, including 12 GI- and 42 GII-positive samples, 1 GI and GII coinfection, and 30 negative samples. Comparison of the assays showed perfect concordance with a kappa coefficient score of 1.00 (95%CI from 1.00 to 1.00). Of the 30 negative stool samples tested, three samples were positive for rotavirus detected using an immunochromatographic assay, with no cross-reactivity shown in both LDT and Xpert assays. In-run sample processing control of the Xpert assay for all negative samples tested showed no/minor inhibition. Compared to the LDT, the Xpert assay produced similar or better Ct values for detection. It also showed better mitigation of PCR inhibition in stool sample testing.
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- 2017
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38. Esophageal Adenocarcinoma–Derived Extracellular Vesicle MicroRNAs Induce a Neoplastic Phenotype in Gastric Organoids
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Christopher Ng, Rong Yan, Yulan Cheng, Xiquan Ke, John M. Abraham, Jee Hoon Song, Binbin Huang, Zhixiong Wang, Xi Liu, Xu Shu, Nonghua Lu, Shuixiang He, Eun Ji Shin, Stephen J. Meltzer, Zhe Wang, Amy Meltzer, Zhenguo Sun, and Sariat Ibrahim
- Subjects
0301 basic medicine ,Original article ,Cancer Research ,Pathology ,medicine.medical_specialty ,Esophageal Neoplasms ,Cell Survival ,Adenocarcinoma ,lcsh:RC254-282 ,Extracellular Vesicles ,03 medical and health sciences ,Cell Line, Tumor ,Immunochemistry ,Organoid ,medicine ,Humans ,PTEN ,Viability assay ,biology ,Cell growth ,Extracellular vesicle ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,Phenotype ,Coculture Techniques ,Cell biology ,Organoids ,MicroRNAs ,Cell Transformation, Neoplastic ,030104 developmental biology ,Gastric Mucosa ,Cell culture ,biology.protein - Abstract
There have been no reports describing the effects of cancer cell–derived extracellular vesicles (EVs) on three-dimensional organoids. In this study, we delineated the proneoplastic effects of esophageal adenocarcinoma (EAC)–derived EVs on gastric organoids (gastroids) and elucidated molecular mechanisms underlying these effects. EVs were identified using PKH-67 staining. Morphologic changes, Ki-67 immunochemistry, cell viability, growth rates, and expression levels of miR-25 and miR-210, as well as of their target mRNAs, were determined in gastroids co-cultured with EAC-derived extracellular vesicles (c-EVs). C-EVs were efficiently taken up by gastroids. Notably, c-EV–treated gastroids were more crowded, compact, and multilayered and contained smaller lumens than did those cultured in organoid medium alone or in EAC-conditioned medium that had been depleted of EVs. Moreover, c-EV–treated gastroids manifested increased proliferation and cellular viability relative to medium-only or EV-depleted controls. Expression levels of miR-25 and miR-210 were significantly higher, and those of PTEN and AIFM3 significantly lower, in c-EV–treated versus medium-only or EV-depleted control groups. Inhibitors of miR-25 and miR-210 reversed the increased cell proliferation induced by c-exosomes in co-cultured gastroids by lowering miR-25 and miR-210 levels. In conclusion, we have constructed a novel model system featuring the co-culture of c-EVs with three-dimensional gastroids. Using this model, we discovered that cancer-derived EVs induce a neoplastic phenotype in gastroids. These changes are due, at least in part, to EV transfer of miR-25 and miR-210.
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- 2017
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39. Identifying large indels in targeted next generation sequencing assays for myeloid neoplasms: a cautionary tale of the ZRSR1 pseudogene
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Chin Hin Ng, Jia Jin Low, Christopher Ng, Isaac Ks Ng, Benedict Yan, Wee Joo Chng, Lily Chiu, Elaine Seah, and Kenneth Hon Kim Ban
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0301 basic medicine ,Genetics ,medicine.medical_specialty ,Myeloid ,Molecular pathology ,Pseudogene ,General Medicine ,Biology ,DNA sequencing ,Pathology and Forensic Medicine ,03 medical and health sciences ,030104 developmental biology ,medicine.anatomical_structure ,Open source ,hemic and lymphatic diseases ,Molecular genetics ,medicine ,In patient ,Indel - Abstract
Targeted next generation sequencing platforms have been increasingly utilised for identification of novel mutations in myeloid neoplasms, such as acute myeloid leukaemia (AML), and hold great promise for use in routine clinical diagnostics. In this study, we evaluated the utility of an open source variant caller in detecting large indels in a targeted sequencing of AML samples. While we found that this bioinformatics pipeline has the potential to accurately capture large indels (>20 bp) in patient samples, we highlighted the pitfall of a confounding ZRSR1 pseudogene that led to an erroneous ZRSR2 variant call. We further discuss possible clinical implications of the ZRSR1 pseudogene in myeloid neoplasms based on its molecular features. Knowledge of the confounding ZRSR1 pseudogene in ZRSR2 sequencing assays could be particularly important in AML diagnostics because the detection of ZRSR2 in AML patients is highly specific for an s-AML diagnosis.
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- 2017
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40. Diagnostic Imaging of Nasopharyngeal Carcinoma
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Donovan Eu, Clement Yong, Timothy Cheo, Vincent Chong, Lih Khin Khor, Justin Christopher Ng, and Balamurugan Vellayappan
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medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Magnetic resonance imaging ,medicine.disease ,Multidisciplinary team ,Radiological anatomy ,stomatognathic diseases ,Treatment complications ,Nasopharyngeal carcinoma ,Radiological weapon ,otorhinolaryngologic diseases ,medicine ,Medical imaging ,Medical physics ,business ,Staging system - Abstract
Our knowledge of nasopharyngeal carcinoma (NPC) is rapidly changing. This article is a snapshot of the present state of NPC imaging in relation to the latest staging system, current standards of care, and treatment complications. The article’s emphasis on pathophysiology and important radiological anatomy will improve the interpretation of radiological findings and allow the radiologist to optimize the role of imaging in a multidisciplinary team.
- Published
- 2020
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41. Functional analysis of Niemann-Pick disease type C family protein, NPC1a, in Drosophila melanogaster
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Paul Schedl, Diane Manry, Girish Deshpande, Rachel Kalifa, Victoria Moyal, Christopher Ng, Offer Gerlitz, Sol Zamir, Yunah Kim, Peyton Smith, and Tzofia Bialistoky
- Subjects
Germ cell migration ,Somatic cell ,Precursor cell ,Cell migration ,Biology ,Drosophila melanogaster ,biology.organism_classification ,Molecular Biology ,Embryonic stem cell ,Hedgehog ,Hedgehog signaling pathway ,Developmental Biology ,Cell biology - Abstract
During embryonic gonad coalescence, primordial germ cells (PGCs) follow a carefully choreographed migratory route circumscribed by guidance signals towards somatic gonadal precursor cells (SGPs). In Drosophila melanogaster, SGP-derived Hedgehog (Hh), which serves as a guidance cue for the PGCs, is potentiated by mesodermally restricted HMGCoA-reductase (Hmgcr) and the ABC transporter Multi-drug-resistant-49 (Mdr49). Given the importance of cholesterol modification in the processing and long-distance transmission of the Hh ligand, we have analyzed the involvement of the Niemann-Pick disease type C-1a (NPC1a) protein, a cholesterol transporter, in germ cell migration and Hedgehog signaling. We show that mesoderm-specific inactivation of Npc1a results in germ cell migration defects. Similar to Mdr49, PGC migration defects in the Npc1a embryos are ameliorated by a cholesterol-rich diet. Consistently, reduction in Npc1a weakens the ability of ectopic HMG Coenzyme A reductase (Hmgcr) to induce germ cell migration defects. Moreover, compromising Npc1a levels influences Hh signaling adversely during wing development, a process that relies upon long-range Hh signaling. Last, doubly heterozygous embryos (Mdr49/Npc1a) display enhanced germ cell migration defects when compared with single mutants (Npc1a/+ or Mdr49/+), supporting cooperative interaction between the two.
- Published
- 2019
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42. Analyzing Machine Learning Workloads Using a Detailed GPU Simulator
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Negar Goli, Amruth Sandhupatla, Christopher Ng, Timothy G. Rogers, Suchita Pati, Deval Shah, Shaylin Cattell, Tor M. Aamodt, Jonathan Lew, Mengchi Zhang, and Matthew D. Sinclair
- Subjects
FOS: Computer and information sciences ,010302 applied physics ,Measure (data warehouse) ,Source code ,business.industry ,Computer science ,media_common.quotation_subject ,02 engineering and technology ,Architecture design ,Machine learning ,computer.software_genre ,01 natural sciences ,Execution time ,020202 computer hardware & architecture ,Computer Science - Distributed, Parallel, and Cluster Computing ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Deep neural networks ,Distributed, Parallel, and Cluster Computing (cs.DC) ,Artificial intelligence ,Architecture ,business ,computer ,Simulation ,media_common - Abstract
Most deep neural networks deployed today are trained using GPUs via high-level frameworks such as TensorFlow and PyTorch. This paper describes changes we made to the GPGPU-Sim simulator to enable it to run PyTorch by running PTX kernels included in NVIDIA's cuDNN library. We use the resulting modified simulator, which has been made available publicly with this paper, to study some simple deep learning workloads. With our changes to GPGPU-Sim's functional simulation model, we find GPGPU-Sim performance model running a cuDNN enabled implementation of LeNet for MNIST reports results within 30% of real hardware. Using GPGPU-Sim's AerialVision performance analysis tool we observe that cuDNN API calls contain many varying phases and appear to include potentially inefficient microarchitecture behaviour such as DRAM partition bank camping, at least when executed on GPGPU-Sim's current performance model., Source code available at: https://github.com/gpgpu-sim/gpgpu-sim_distribution/tree/dev
- Published
- 2019
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43. Single-cell genomic profiling of acute myeloid leukemia for clinical use: A pilot study
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Zenia Tiang, Kenneth Hon Kim Ban, Wilson Lek Wen Tan, Roger Foo, Wee Joo Chng, Joanne Lee, Christopher Ng, Chin Hin Ng, Tin Wee Tan, Elaine Seah, Yongli Hu, Benedict Yan, and Lily Chiu
- Subjects
0301 basic medicine ,Cancer Research ,Cell ,Myeloid leukemia ,Genomics ,Articles ,acute myeloid leukemia ,Biology ,Cell cycle ,Bioinformatics ,single cell ,3. Good health ,Transcriptome ,transcriptomics ,03 medical and health sciences ,030104 developmental biology ,medicine.anatomical_structure ,Oncology ,Gene expression ,genomics ,gene expression ,medicine ,Profiling (information science) ,Gene - Abstract
Although bulk high-throughput genomic profiling studies have led to a significant increase in the understanding of cancer biology, there is increasing awareness that bulk profiling approaches do not completely elucidate tumor heterogeneity. Single-cell genomic profiling enables the distinction of tumor heterogeneity, and may improve clinical diagnosis through the identification and characterization of putative subclonal populations. In the present study, the challenges associated with a single-cell genomics profiling workflow for clinical diagnostics were investigated. Single-cell RNA-sequencing (RNA-seq) was performed on 20 cells from an acute myeloid leukemia bone marrow sample. Putative blasts were identified based on their gene expression profiles and principal component analysis was performed to identify outlier cells. Variant calling was performed on the single-cell RNA-seq data. The present pilot study demonstrates a proof of concept for clinical single-cell genomic profiling. The recognized limitations include significant stochastic RNA loss and the relatively low throughput of the current proposed platform. Although the results of the present study are promising, further technological advances and protocol optimization are necessary for single-cell genomic profiling to be clinically viable.
- Published
- 2017
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44. Clinical implications ofDNMT3Amutations in a Southeast Asian cohort of acute myeloid leukaemia patients
- Author
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Lily Chiu, Bee Choo Tai, Christopher Ng, Wee Joo Chng, Mingxuan Lin, Benedict Yan, Zhaojin Chen, Isaac Ks Ng, Chin Hin Ng, Elaine Seah, Marcus Hwai Yik Tan, and Kenneth Hon Kim Ban
- Subjects
0301 basic medicine ,Oncology ,medicine.medical_specialty ,NPM1 ,Epigenetic modifier ,Population ,Southeast asian ,Pathology and Forensic Medicine ,03 medical and health sciences ,0302 clinical medicine ,hemic and lymphatic diseases ,Internal medicine ,White blood cell ,Medicine ,education ,Survival analysis ,education.field_of_study ,business.industry ,General Medicine ,030104 developmental biology ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,embryonic structures ,Immunology ,Cohort ,Myeloid leukaemia ,business - Abstract
Aims In recent years, genomic technologies have enabled the identification of mutations in acute myeloid leukaemia (AML). DNMT3A is a recurrently mutated epigenetic modifier gene in AML. To date, the prognostic significance of DNMT3A mutations has not been studied in a Southeast Asian AML population. We sought to investigate the clinical implications of DNMT3A mutations in a Southeast Asian cohort of AML patients. Methods DNMT3A mutations were identified using a targeted next-generation sequencing panel in 157 AML patients. We studied the molecular and clinical features of patients with DNMT3A mutations and assessed the prognostic impact of DNMT3A mutations. Results DNMT3A mutations were found in 33 of 157 (21.0%) AML patients. 114 patients were included for statistical analysis. Pretreatment data revealed that patients with DNMT3A mutations were older (≥60 years old), had a higher white blood cell count at diagnosis, had more adverse cytogenetic risk profiles and were more often associated with NPM1 mutations compared with patients with wild-type DNMT3A . Survival analysis showed that DNMT3A mutations were associated with poorer clinical outcomes. This was especially when associated with NPM1 and FLT3-ITD mutations (AML NPM1/FLT3/DNMT3A ), which are common. The AML NPM1/FLT3/DNMT3A subtype was an independent predictor for poorer overall survival (OS). Other independent risk factors for poorer OS include advanced age at diagnosis and adverse cytogenetic risk stratification. Conclusions DNMT3A mutations are associated with an unfavourable clinical outcome in our Southeast Asian AML patient cohort. In particular, AML NPM1/FLT3/DNMT3A patients had the poorest prognosis.
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- 2017
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45. Quantum Dot Based Multiwavelength Fluorescence Detection Using KODAK Image Station 2000MM
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Theresa F. Harper and Christopher Ng
- Subjects
Biology (General) ,QH301-705.5 - Published
- 2005
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46. A non-invasive method to produce pressure ulcers of varying severity in a spinal cord-injured rat model
- Author
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Rachel Sarabia-Estrada, R Cohen, Daniel M. Sciubba, Ian Suk, Charles Steenbergen, Amir Mehdi Ansari, Guy P. Marti, Christopher Ng, Frank Lay, Aerielle E. Matsangos, Ali Karim Ahmed, Neil A. Phillips, Courtney Rory Goodwin, Nancy Abu-Bonsrah, Louis J. Born, C Pang, and John W. Harmon
- Subjects
0206 medical engineering ,Ischemia ,02 engineering and technology ,Thoracic Vertebrae ,Microcirculation ,Rats, Sprague-Dawley ,Leukocyte Count ,030207 dermatology & venereal diseases ,03 medical and health sciences ,0302 clinical medicine ,White blood cell ,Laser-Doppler Flowmetry ,Pressure ,medicine ,Animals ,Creatine Kinase ,Spinal cord injury ,Spinal Cord Injuries ,Pressure Ulcer ,business.industry ,General Medicine ,Blood flow ,Hypoxia (medical) ,medicine.disease ,020601 biomedical engineering ,Disease Models, Animal ,medicine.anatomical_structure ,Neurology ,Blood chemistry ,Regional Blood Flow ,Anesthesia ,Female ,Neurology (clinical) ,medicine.symptom ,business ,Perfusion ,Blood Chemical Analysis - Abstract
Experimental study. The objective of this study was to establish a non-invasive model to produce pressure ulcers of varying severity in animals with spinal cord injury (SCI). The study was conducted at the Johns Hopkins Hospital in Baltimore, Maryland, USA. A mid-thoracic (T7–T9) left hemisection was performed on Sprague-Dawley rats. At 7 days post SCI, rats received varying degrees of pressure on the left posterior thigh region. Laser Doppler Flowmetry was used to record blood flow. Animals were killed 12 days after SCI. A cardiac puncture was performed for blood chemistry, and full-thickness tissue was harvested for histology. Doppler blood flow after SCI prior to pressure application was 237.808±16.175 PFUs at day 7. Following pressure application, there was a statistically significant decrease in blood flow in all pressure-applied groups in comparison with controls with a mean perfusion of 118.361±18.223 (P
- Published
- 2016
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47. Pharmacological Interventions in Older Adults
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Dale W. Smith, John Heafner, George T. Grossberg, Jay J. Patel, and Christopher Ng
- Subjects
medicine.medical_specialty ,Side effect ,business.industry ,Adult population ,Psychological intervention ,Cognition ,Mental illness ,medicine.disease ,Mood ,Pharmacological interventions ,Medicine ,Dosing ,business ,Intensive care medicine - Abstract
In this chapter, we discuss the different pharmacological interventions for psychiatric diseases in the geriatric population. We specifically divide these treatments into five categories: anxiolytics and sedative-hypnotics, antipsychotics, antidepressants, mood stabilizers, and cognitive enhancers. These categories are further divided into disease-specific medications. The utility, general recommendations, mechanism of action, dosing, and adverse reactions of drugs are covered for the medications in this chapter. The treatment of mental illness in the geriatric population is a complicated process due to the physiologic changes of metabolism, drug absorption, and drug excretion. These transformations specifically alter the dosing of pharmacological treatments in older adults. The shift in metabolism inherently changes the side effect profile of medications compared to the general adult population, which further complicates the utilization of pharmaceutical interventions for older adults with psychiatric conditions. It is our goal to provide a solid background for clinicians to make prudent decisions in the treatment approach of psychiatric diseases in the geriatric population.
- Published
- 2019
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48. Integrating cybersecurity in hazard and risk analyses
- Author
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Christopher Ng and Addie Cormier
- Subjects
Risk analysis ,Computer science ,General Chemical Engineering ,Control (management) ,Energy Engineering and Power Technology ,02 engineering and technology ,Management Science and Operations Research ,Computer security ,computer.software_genre ,Industrial and Manufacturing Engineering ,020401 chemical engineering ,Vulnerability assessment ,0502 economics and business ,050207 economics ,0204 chemical engineering ,Safety, Risk, Reliability and Quality ,Process safety management ,business.industry ,05 social sciences ,Information technology ,Hazard ,Process control network ,Control and Systems Engineering ,Process Hazard Analysis ,business ,computer ,Food Science - Abstract
As operational and information technologies converge to allow for remote and real-time access to plant operating data and control functions, the process industry could become increasingly susceptible to cyber-attacks. Traditional hazard and risk analysis methods appear inadequate to identify, prevent, and mitigate such attacks. This paper discusses the significance of incorporating cybersecurity vulnerability analysis not just as part of process hazard analysis (PHA), but also in terms of protecting the process control network and implementing adequate safeguards in general against cyber threats. A layer of protection analysis (LOPA) is adapted to evaluate potential weaknesses and ensure safeguards for critical applications would be resistant to cyber-attacks. Integrating cybersecurity into hazard and risk analyses as well as other elements of process safety management (PSM) is demonstrated with examples, making the plant more resilient against both traditional and cyber threats.
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- 2020
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49. Current state of acute stroke care in Southeast Asian countries
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Jeyaledchumy Mahadevan, Luu Dang Vu, Anchalee Churojana, S. Pongpech, Cindy Sadikin, Wickly Lee, Justin Christopher Ng, Josephine Subramaniam, and Victor Erwin Jocson
- Subjects
medicine.medical_specialty ,Population ageing ,medicine.medical_treatment ,Psychological intervention ,Vascular risk ,Southeast asian ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Health care ,medicine ,Humans ,cardiovascular diseases ,Intensive care medicine ,Stroke ,Asia, Southeastern ,Acute stroke ,Thrombectomy ,Ischemic Stroke ,business.industry ,Endovascular Procedures ,Thrombolysis ,medicine.disease ,business ,Delivery of Health Care ,030217 neurology & neurosurgery - Abstract
Acute stroke care systems in Southeast Asian countries are at various stages of development, with disparate treatment availability and practice in terms of intravenous thrombolysis and endovascular therapy. With the advent of successful endovascular therapy stroke trials over the past decade, the pressure to revise and advance acute stroke management has greatly intensified. Southeast Asian patients exhibit unique stroke features, such as increased susceptibility to intracranial atherosclerosis and higher prevalence of intracranial haemorrhage, likely secondary to modified vascular risk factors from differing dietary and lifestyle habits. Accordingly, the practice of acute endovascular stroke interventions needs to take into account these considerations. Acute stroke care systems in Southeast Asia also face a unique challenge of huge stroke burden against a background of ageing population, differing political landscape and healthcare systems in these countries. Building on existing published data, further complemented by multi-national interaction and collaboration over the past few years, the current state of acute stroke care systems with existing endovascular therapy services in Southeast Asian countries are consolidated and analysed in this review. The challenges facing acute stroke care strategies in this region are discussed.
- Published
- 2018
50. Taking a stand for operative vaginal delivery
- Author
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Christopher Ng
- Subjects
Pregnancy ,medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,Previous cesarean ,Vaginal delivery ,business.industry ,Obstetrics ,Research ,MEDLINE ,Trial of labour ,Obstetrical Forceps ,Infant, Newborn ,General Medicine ,medicine.disease ,Delivery, Obstetric ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Humans ,Female ,030212 general & internal medicine ,Cesarean delivery ,business - Abstract
See related articles at [[www.cmaj.ca/lookup/doi/10.1503/cmaj.171076][2]][2] and [[www.cmaj.ca/lookup/doi/10.1503/cmaj.170371][3]][3] KEY POINTS Against a background of growing concern that rates of cesarean delivery in Canada and globally are rising, trial of labour after previous cesarean
- Published
- 2018
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