211 results on '"Y.-S. Chan"'
Search Results
2. Providing psychiatric diagnosis and intervention in patients with chronic medical illness in the community: A novel collaboration between the Psychiatry team and the community team in a Singapore restructured hospital
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W. S. Lee, G. S. Lim, H. Y. Goh, and Y. S. Chan
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Psychiatry ,RC435-571 - Abstract
Introduction Home nursing and medical services have an established role in delivering chronic medical care to populations which face difficulty accessing physical clinics. Those with chronic medical conditions and reduced mobility face a higher likelihood of suffering from psychiatric co-morbidity. However, till date there has been limited research done on home-based psychiatric care in this population. Since 2021, the Psychiatry department of Tan Tock Seng Hospital (TTSH) has been collaborating with TTSH Community Health Team (CHT) to manage potential psychiatric issues in community patients. These patients would be discussed in a weekly multidisciplinary setting. If indicated, home visit by both teams for home-based assessment and treatment would be arranged, allowing for detection and treatment of psychiatric illness. Objectives To demonstrate that the collaboration between the psychiatry team and CHT leads to diagnosis and treatment of psychiatric illness in a population that might otherwise have been unable to access psychiatric services. Methods We performed a retrospective study on all referrals from the CHT to the psychiatry team, within the 2-year period of August 2021 to August 2023. We collected demographic information, psychiatric history prior to referral, reason for referral, outcome of multidisciplinary discussion, and outcome of the home visits (including diagnoses made, and medications initiated). Results A total of 92 patients were referred by the CHT to the psychiatry team. Most were elderly with multiple medical co-morbidities; of note, a history of stroke was present in 24 of the referred patients. Common reasons for referral include suspected mental illness, risk assessment, and management of behavioural issues. 28 of the referred patients did not have a prior psychiatric history at the point of referral. Among these, home visits involving the psychiatric team were done for 16 patients. 11 (68%) of these home visits led to diagnosis of a new psychiatric illness. 9 of these patients were initiated on psychotropic medications in the home setting. Conclusions A significant proportion of patients (68% of home visits without prior psychiatric diagnosis) were newly diagnosed with psychiatric illness, allowing early psychiatric intervention to be delivered. This was achieved in a population with a high prevalence of multiple medical comorbidity and barriers to clinic-based psychiatric evaluation and treatment. We propose future comparative studies into how the collaboration between the psychiatric team and community health team can improve the quality of life and caregiver experience of patients with chronic medical problems, as well as how the service had improved the confidence of the community health team in identifying and managing patients with possible psychiatric issues. Disclosure of Interest None Declared
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- 2024
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3. Towards clinical application of GlycA and GlycB for early detection of inflammation associated with (pre)diabetes and cardiovascular disease: recent evidence and updates
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Erik Fung, Eunice Y. S. Chan, Kwan Hung Ng, Ka Man Yu, Huijun Li, and Yulan Wang
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Glycoproteins ,Nuclear magnetic resonance spectroscopy ,Inflammation ,Diabetes mellitus ,Atherosclerosis ,Cardiovascular disease ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Abstract Summary Cardiometabolic diseases are associated with low-grade inflammation early in life and persists into old age. The long latency period presents opportunities for early detection, lifestyle modification and intervention. However, the performance of conventional biomarker assays to detect low-grade inflammation has been variable, particularly for early-stage cardiometabolic disorder including prediabetes and subclinical atherosclerotic vascular inflammation. During the last decade, the application of nuclear magnetic resonance (NMR) spectroscopy for metabolic profiling of biofluids in translational and epidemiological research has advanced to a stage approaching clinical application. Proton (1H)-NMR profiling induces no destructible physical changes to specimens, and generates quantitative signals from deconvoluted spectra that are highly repeatable and reproducible. Apart from quantitative analysis of amino acids, lipids/lipoproteins, metabolic intermediates and small proteins, 1H-NMR technology is unique in being able to detect composite signals of acute-phase and low-grade inflammation indicated by glycosylated acetyls (GlycA) and N-acetylneuraminic acid (sialic acid) moieties (GlycB). Different from conventional immunoassays that target epitopes and are susceptible to conformational variation in protein structure and binding, GlycA and GlycB signals are stable over time, and maybe complementary as well as superior to high-sensitivity C-reactive protein and other inflammatory cytokines. Here we review the physicochemical principles behind 1H-NMR profiling of GlycA and GlycB, and the available evidence supporting their potential clinical application for the prediction of incident (pre)diabetes, cardiovascular disease, and adverse outcomes.
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- 2023
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4. Perioperative mortality in low-, middle-, and high-income countries: Protocol for a multi-level meta-regression analysis.
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Kevin J McIntyre, Yun-Hee Choi, Ava John-Baptiste, Daniel J Lizotte, Eunice Y S Chan, Jessica Moodie, Saverio Stranges, and Janet Martin
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Medicine ,Science - Abstract
BackgroundSurgery is an indispensable component of a functional healthcare system. To date there is limited information regarding how many people die during the perioperative period globally. This study describes a protocol for a systematic review and multilevel meta-regression to evaluate time trends regarding the odds of perioperative mortality among adults undergoing a bellwether surgical procedure while accounting for higher order clustering at the national level.MethodsPublished studies reporting the number of perioperative deaths from bellwether surgical procedures among adults will be identified from MEDLINE, Embase, Cochrane CENTRAL, LILACS and Global Index Medicus. The primary outcome will be the rate of perioperative mortality across time and the secondary outcome will be investigating cause of death over time as a proportion of overall perioperative mortality. Two reviewers will independently conduct full text screening and extract the data. Disagreements will first be resolved via consensus. If consensus cannot be reached a third reviewer will be included to arbitrate. Due to human resource limitations, a risk of bias appraisal will not be conducted. From the included studies a multilevel meta-regression will be constructed to synthesize the results. This model will conceptualize patients as nested in studies which are in turn nested within countries while taking into account potential confounding variables at all levels.DiscussionThe systematic review and multilevel meta-regression that will be conducted based on this protocol will provide synthesized global evidence regarding the trends of perioperative mortality. This eventual study may help policymakers and other key stakeholders with benchmarking surgical safety initiatives as well as identify key gaps in our current understanding of global perioperative mortality.Trial registrationSystematic review registration: PROSPERO registration number 429040.
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- 2024
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5. Chaos Game Representation.
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Eunice Y. S. Chan and Robert M. Corless
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- 2023
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6. Impact of Stressors/Stress on Organizational Commitment of Engineers in the Construction Industry
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Mei-Yung Leung, Khursheed Ahmed, and Isabella Y. S. Chan
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engineers ,commitment ,stress management ,stressors ,stress ,Building construction ,TH1-9745 - Abstract
Engineers often play vital roles in technical planning, designing, and operating projects, as well as implementing standard requirements in the physical sites. Although architectural designs may be similar in a construction project, the technical problems, including soil conditions, loading calculations, team combination, etc., often vary between projects. Although previous studies focus on the stress management of construction professionals, little research has been particularly conducted for the effects of stressors and stress of engineers on their organizational commitment. It is inevitable for engineers to experience different uncertainties, harsh working environments, and serious legal liabilities, while there is often no tolerance when it comes to deadlines and safety requirements. All this definitely puts great pressure on them and may subsequently affect their commitment to their organizations. The present study aimed to investigate the impact of stressors and stress on the commitment of engineers in the construction industry. A total of 146 respondents participated in a questionnaire survey, and various statistical analyses including a reliability test, correlation, and hierarchical multiple regressions were adopted for developing the optimized commitment models. The research results revealed that (1) Type A personality was a key factor, which had a significant positive effect on all the three organizational commitments of professional engineers in the construction industry; (2) poor office environment, job overload, and role ambiguity were positively associated with continuance and normative commitment, whereas poor site environment and lack of job autonomy were negatively linked with affective commitment; and (3) stress had a negative relationship with affective commitment; (4) however, there was no relationship between stress and continuance or normative commitment. In order to establish holistic organizational commitment strategies in the industry well, the current study indicates key stressors to upper management to help them efficiently manage complicated project teams in construction projects. In addition, it contributes the body of knowledge by developing an integrated commitment model for engineers. Finally, numerous recommendations are made, such as encouraging Type A personality behaviors, providing sufficient job autonomy, improving worksite conditions to enhance the organizational commitment of engineers, and reducing the adverse impacts of these stressors and stress.
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- 2024
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7. Automatic algorithmic driven monitoring of atrioventricular nodal re-entrant tachycardia ablation to improve procedural safety
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Tsz Kin Tam, Angel Lai, Joseph Y. S. Chan, Alex C. K. Au, Chin Pang Chan, Yuet Wong Cheng, and Bryan P. Yan
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AVNRT ,slow pathway modification ,heart block ,radiofrequency ablation ,automatic algorithm ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
BackgroundDuring slow pathway modification for atrioventricular nodal reentrant tachycardia, heart block may occur if ablation cannot be stopped in time in response to high risk electrogram features (HREF).ObjectivesTo develop an automatic algorithm to monitor HREF and terminate ablation earlier than human reaction.MethodsDigital electrogram data from 332 ablation runs from February 2020 to June 2022 were included. They were divided into training and validation sets which contained 126 and 206 ablation runs respectively. HREF in training set was measured. Then a program was developed with cutoff values decided from training set to capture all these HREF. Simulation ablation videos were rendered using validation set electrogram data. The videos were played to three independent electrophysiologists who each determined when to stop ablation. Timing of ablation termination, sensitivity, and specificity were compared between human and program.ResultsReasons for ablation termination in the training set include short AA time, short VV time, AV block and VA block. Cutoffs for the program were set to maximize program sensitivity. Sensitivity and specificity for the program in the validation set were 95.2% and 91.1% respectively, which were comparable to that of human performance at 93.5% and 95.4%. If HREF were recognized by both human and program, ablations were terminated earlier by the program 90.2% of times, by a median of 574 ms (interquartile range 412–807 ms, p
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- 2023
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8. A Fractal Eigenvector.
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Neil J. Calkin, Eunice Y. S. Chan, Robert M. Corless, David J. Jeffrey, and Piers W. Lawrence
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- 2022
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9. Magnitude of COVID-19 deaths relative to other leading causes of death: a global analysis
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Janet Martin, Davy Cheng, and Eunice Y S Chan
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Medicine - Abstract
Objectives To quantify the burden of death that COVID-19 contributes relative to the top three causes of death for all countries.Design We performed uncertainty analyses and created contour plots for COVID-19 mortality to place the number of COVID-19 deaths in context relative to the top three causes of death in each country, across a plausible range of values for two key parameters: case fatality rate and magnitude of under-reporting.Setting All countries that have reported COVID-19 cases to the WHO and are included in the Global Burden of Disease Study by the Institute of Health Metrics and Evaluation.Main outcomes and measures Monthly number of deaths caused by COVID-19 and monthly number of deaths caused by the top three causes of death for every country.Results For countries that were particularly hard hit during the outbreak in 2020, most combinations of model parameters resulted in COVID-19 ranking within the top three causes of death. For countries not as hard hit on a per-capita basis, such as China and India, COVID-19 did not rank higher than the third leading cause of death at any combination of the model parameters within the given ranges. Up-to-date ranking of COVID-19 deaths relative to the top three causes of death for all countries globally is provided in an interactive online application.Conclusions Estimating the country-level burden of death that COVID-19 contributes relative to the top three causes of death is feasible through contour graphs, even when the actual number of deaths or cases is unknown. This method can help convey importance by placing the magnitude of COVID-related deaths in context relative to more familiar causes of death by communicating when COVID-related deaths rank among the top three causes of death.
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- 2022
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10. Treatment outcomes of T and natural‐killer/T‐cell lymphoma with ifosfamide, carboplatin and etoposide chemotherapy
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Tricia Tay, Nagavalli Somasundaram, Cindy Lim, Lay Poh Khoo, Allan Zhi Kai Goh, Yuh Shan Lee, Xin Liu, Miriam Tao, Richard Quek, Mohamad Farid, Eileen Poon, Jason Y. S. Chan, Esther W. Y. Chang, Valerie S. W. Yang, Yeow Tee Goh, Daryl Tan, Colin Diong, Nicholas F. Grigoropoulos, Chandramouli Nagarajan, Michelle Poon, Sanjay deMel, Anand Jeyasekharan, Esther H. L. Chan, Joanne Lee, Yen Lin Chee, Soon Thye Lim, and Tiffany Tang
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Asia ,chemotherapy ,haematology–oncology ,natural‐killer/T‐cell lymphoma ,T‐cell lymphoma ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Contemporary data of peripheral T‐cell lymphoma (PTCL) and natural‐killer/T‐cell lymphoma (NKTL) patients treated with ifosfamide, carboplatin and etoposide (ICE) are limited. Aims We performed a retrospective analysis to estimate outcomes of ICE‐treated PTCL and NKTL patients at three tertiary cancer centres in Singapore. Methods and Results Patients were identified through lymphoma databases from National Cancer Centre Singapore (NCCS), National University Hospital, Singapore (NUHS), and Singapore General Hospital (SGH). Responses and survival outcomes were determined from electronic medical records. A total of 75 patients with a median age of 50 were included. ICE was used as first‐line treatment in 14 patients (19%) and as subsequent lines of treatment in 61 patients (81%). The overall response rates (ORR) for all patients was 63% (40% complete response [CR]). The ORR and CR in the first line were 86% and 64% respectively. At a median follow‐up duration of 71.0 months, the median progression‐free (PFS) and overall survival (OS) for all patients were 4.4 months (95%CI, 2.7–6.0) and 16 months (95%CI, 8.3–45.4) respectively. Conclusion In summary, ICE showed high ORR but poor PFS in relapsed/refractory PTCL and NKTL. ORR of ICE in the first line setting appears better than real‐world CHOP data and warrants further study.
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- 2022
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11. Evaluation of a Restoration Algorithm Applied to Clipped Tibial Acceleration Signals
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Zoe Y. S. Chan, Chloe Angel, Daniel Thomson, Reed Ferber, Sharon M. H. Tsang, and Roy T. H. Cheung
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operating range ,accelerometer ,peak tibial acceleration ,interpolation ,wearable sensors ,Chemical technology ,TP1-1185 - Abstract
Wireless accelerometers with various operating ranges have been used to measure tibial acceleration. Accelerometers with a low operating range output distorted signals and have been found to result in inaccurate measurements of peaks. A restoration algorithm using spline interpolation has been proposed to restore the distorted signal. This algorithm has been validated for axial peaks within the range of 15.0–15.9 g. However, the accuracy of peaks of higher magnitude and the resultant peaks have not been reported. The purpose of the present study is to evaluate the measurement agreement of the restored peaks using a low-range accelerometer (±16 g) against peaks sampled using a high-range accelerometer (±200 g). The measurement agreement of both the axial and resultant peaks were examined. In total, 24 runners were equipped with 2 tri-axial accelerometers at their tibia and completed an outdoor running assessment. The accelerometer with an operating range of ±200 g was used as reference. The results of this study showed an average difference of −1.40 ± 4.52 g and −1.23 ± 5.48 g for axial and resultant peaks. Based on our findings, the restoration algorithm could skew data and potentially lead to incorrect conclusions if used without caution.
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- 2023
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12. Lessons Learned from the COVID-19 Pandemic: A Multigroup Structural Equation Modelling of Underground Space Environment and Users’ Health
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Isabelle Y. S. Chan and Hao Chen
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COVID-19 pandemic ,physical health ,pre- and post-outbreak ,psychological health ,underground environment ,Building construction ,TH1-9745 - Abstract
Due to the inherent limitations of underground spaces, such as the lack of natural ventilation and sunlight, underground space users tend to face more health risks compared with their aboveground counterparts. However, little is known about how the underground environment, users’ health, and their associations were impacted by the outbreak of the pandemic. In this study, we investigated and compared the impacts of the general underground environment on regular users’ physical and psychological health before and after the pandemic. To achieve this aim, the data from 525 surveys were collected from eleven underground sites, followed by an objective field measurement study conducted at five underground sites in Hong Kong pre- and post-outbreak of the pandemic. The multigroup structural equation modelling results indicated that: (i) surprisingly, the users’ satisfaction towards almost all underground environment factors, including greenery, connectivity with the aboveground environment, thermal comfort, ventilation, indoor air quality, acoustic comfort, and lighting, excluding wayfinding, were significantly higher in the post-outbreak period; (ii) the users’ health, both physical and psychological, was significantly better in the post-outbreak period; (iii) the impacts of visual comfort on the users’ physical and psychological health were significantly greater in the post-outbreak period (critical difference ratio (|CDR|) > 1.96); (iv) the impacts of wayfinding, greenery, and acoustic and thermal comfort on the users’ physical or psychological health were significant only in the pre-outbreak period (|CDR| > 1.96); (v) the impacts of connectivity on the users’ physical and psychological health were significant in both the pre- and post-outbreak periods (|CDR| < 1.96). The findings were further cross-validated using the objective measurement results. With an increasing need to develop healthy underground spaces, the study contributes to the development, design, and management of the underground environment to enhance the users’ health in the post-outbreak era.
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- 2023
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13. Plasticity of muscle synergies through fractionation and merging during development and training of human runners
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Vincent C. K. Cheung, Ben M. F. Cheung, Janet H. Zhang, Zoe Y. S. Chan, Sophia C. W. Ha, Chao-Ying Chen, and Roy T. H. Cheung
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Science - Abstract
Motor commands for human locomotion are generated by combination of muscle synergies. In humans, muscle synergies for running exhibit considerable plasticity during child-to-adult development and adult training to meet the constantly changing biomechanical and efficiency demands.
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- 2020
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14. Evaluation of COVID-19 Restrictions on Distance Runners' Training Habits Using Wearable Trackers
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Zoe Y. S. Chan, Rhys Peeters, Gladys Cheing, Reed Ferber, and Roy T. H. Cheung
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wearables ,activity monitoring ,coronavirus ,training intensity ,training frequency ,Sports ,GV557-1198.995 - Abstract
The COVID-19 pandemic caused widespread disruption to many individuals' lifestyles. Social distancing restrictions implemented during this global pandemic may bring potential impact on physical activity habits of the general population. However, running is one of the most popular forms of physical activity worldwide and one in which it could be maintained even during most COVID-19 restrictions. We aimed to determine the impact of COVID-19 restrictions on runners' training habits through analyzing the training records obtained from their GPS enabled wearable trackers. Retrospective and prospective data were collected from an online database (https://wetrac.ucalgary.ca). Runners' training habits, including frequency, intensity and duration of training, weekly mileage and running locations were analyzed and compared 9 months before and after the start of COVID-19 restrictions in March 2020. We found that runners ran 3 km per week more (p = 0.05, Cohen's d = 0.12) after the start of COVID-19 restrictions, and added 0.3 training sessions per week (p = 0.03, Cohen's d = 0.14). Moreover, runners ran an additional 0.4 sessions outdoors (p < 0.01, Cohen's d = 0.21) but there was no significant change in the intensity or duration of training sessions. Our findings suggested that runners adopted slightly different training regimen as a result of COVID-19 restrictions. Our results described the collective changes, irrespective of differences in response measures adopted by various countries or cities during the COVID-19 pandemic.
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- 2022
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15. Minimal Height Companion Matrices for Euclid Polynomials.
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Eunice Y. S. Chan and Robert M. Corless
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- 2019
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16. Impact of COVID-19 on excess mortality, life expectancy, and years of life lost in the United States.
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Eunice Y S Chan, Davy Cheng, and Janet Martin
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Medicine ,Science - Abstract
This paper quantifies the net impact (direct and indirect effects) of the pandemic on the United States population in 2020 using three metrics: excess deaths, life expectancy, and total years of life lost. The findings indicate there were 375,235 excess deaths, with 83% attributable to direct, and 17% attributable to indirect effects of COVID-19. The decrease in life expectancy was 1.67 years, translating to a reversion of 14 years in historical life expectancy gains. Total years of life lost in 2020 was 7,362,555 across the USA (73% directly attributable, 27% indirectly attributable to COVID-19), with considerable heterogeneity at the individual state level.
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- 2021
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17. Inner Bohemian inverses.
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Eunice Y. S. Chan, Robert M. Corless, Laureano González-Vega, J. Rafael Sendra, and Juana Sendra
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- 2022
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18. Screening for Fabry Disease in patients with unexplained left ventricular hypertrophy.
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Chandu Sadasivan, Josie T Y Chow, Bun Sheng, David K H Chan, Yiting Fan, Paul C L Choi, Jeffrey K T Wong, Mabel M B Tong, Tsz-Ngai Chan, Erik Fung, Kevin K H Kam, Joseph Y S Chan, Wai-Kin Chi, D Ian Paterson, Manohara Senaratne, Neil Brass, Gavin Y Oudit, and Alex P W Lee
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Medicine ,Science - Abstract
Fabry Disease (FD) is a systemic disorder that can result in cardiovascular, renal, and neurovascular disease leading to reduced life expectancy. FD should be considered in the differential of all patients with unexplained left ventricular hypertrophy (LVH). We therefore performed a prospective screening study in Edmonton and Hong Kong using Dried Blood Spot (DBS) testing on patients with undiagnosed LVH. Participants found to have unexplained LVH on echocardiography were invited to participate and subsequently subjected to DBS testing. DBS testing was used to measure α-galactosidase (α-GAL) enzyme activity and for mutation analysis of the α-galactosidase (GLA) gene, both of which are required to make a diagnosis of FD. DBS testing was performed as a screening tool on patients (n = 266) in Edmonton and Hong Kong, allowing for detection of five patients with FD (2% prevalence of FD) and one patient with hydroxychloroquine-induced phenocopy. Left ventricular mass index (LVMI) by GLA genotype showed a higher LVMI in patients with IVS4 + 919G > A mutations compared to those without the mutation. Two patients were initiated on ERT and hydroxychloroquine was discontinued in the patient with a phenocopy of FD. Overall, we detected FD in 2% of our screening cohort using DBS testing as an effective and easy to administer screening tool in patients with unexplained LVH. Utilizing DBS testing to screen for FD in patients with otherwise undiagnosed LVH is clinically important due to the availability of effective therapies and the value of cascade screening in extended families.
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- 2020
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19. γδ T cell frequencies are altered in HIV positive pregnant South African women and are associated with preterm birth.
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Charlene Akoto, Christina Y S Chan, Krithi Ravi, Wei Zhang, Manu Vatish, Shane A Norris, and Joris Hemelaar
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Medicine ,Science - Abstract
BackgroundPreterm birth is the leading cause of neonatal and child mortality worldwide. Maternal HIV infection and antiretroviral treatment (ART) increase the rate of preterm birth, but the underlying mechanisms remain unknown, limiting progress in prediction, prevention and treatment. While overall γδ T cell levels remain constant, acute HIV infection is associated with a depletion of the Vδ2 subset and an increase in the Vδ1 subset, which do not return to baseline with ART. γδ T cells have also been implicated in adverse pregnancy outcomes and we therefore investigated the potential association between maternal HIV infection, peripheral γδ T cell frequencies and preterm birth.MethodsStudy participants were HIV positive (n = 47) and HIV negative (n = 45) women enrolled in a prospective pregnancy cohort study at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa. Women were enrolled in early pregnancy and gestational age was accurately determined by first trimester ultrasound scan. Peripheral blood samples were collected in each trimester and peripheral blood mononuclear cells isolated. Frequencies of γδ T cells, Vδ1+ and Vδ2+ γδ T cell subsets, and CCR6 chemokine receptor expression were determined by flow cytometry.ResultsTotal γδ T cell levels were similar between HIV positive and HIV negative women throughout pregnancy. However, in each trimester maternal HIV infection was associated with reduced levels of the Vδ2+ subset and increased levels of the Vδ1+ subset, leading to a reversal of the Vδ1/Vδ2 ratio. Timing of ART initiation among HIV positive women did not affect levels of γδ T cells, the Vδ1+ and Vδ2+ subsets, or the Vδ1/Vδ2 ratio. Importantly, preterm birth was associated with lower total γδ T cell levels in early pregnancy and γδ T cell frequencies were lowest in HIV positive women who delivered preterm. Moreover, in the first trimester the proportion of Vδ1+ T cells that were CCR6+ was significantly reduced in HIV+ women and women who delivered preterm, resulting in the lowest proportion of CCR6+ Vδ1 T cells in HIV positive women who delivered preterm.ConclusionsOur findings suggest that altered γδ T cell frequencies may link maternal HIV infection and preterm birth. γδ T cell frequencies in early pregnancy may serve as predictive biomarkers to identify women at risk of delivering preterm.
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- 2020
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20. Time trend and characteristics of prostate cancer diagnosed in Hong Kong (China) in the past two decades
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Ho-Fai Wong, Chi-Hang Yee, Jeremy Y C Teoh, Samson Y S Chan, Peter K F Chiu, Ho-Yuen Cheung, Simon S M Hou, and Chi Fai Ng
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Diseases of the genitourinary system. Urology ,RC870-923 - Published
- 2019
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21. Upper Hessenberg and Toeplitz Bohemians.
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Eunice Y. S. Chan, Robert M. Corless, Laureano González-Vega, J. Rafael Sendra, and Juana Sendra
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- 2019
22. Game Theoretic Models for Competition in Public Transit Services.
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Eddie Y. S. Chan and Janny M. Y. Leung
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- 2015
23. Sensor-Based Gait Retraining Lowers Knee Adduction Moment and Improves Symptoms in Patients with Knee Osteoarthritis: A Randomized Controlled Trial
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Sizhong Wang, Peter P. K. Chan, Ben M. F. Lam, Zoe Y. S. Chan, Janet H. W. Zhang, Chao Wang, Wing Kai Lam, Kevin Ki Wai Ho, Rosa H. M. Chan, and Roy T. H. Cheung
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knee osteoarthritis ,medial knee loading ,gait retraining ,machine learning ,Chemical technology ,TP1-1185 - Abstract
The present study compared the effect between walking exercise and a newly developed sensor-based gait retraining on the peaks of knee adduction moment (KAM), knee adduction angular impulse (KAAI), knee flexion moment (KFM) and symptoms and functions in patients with early medial knee osteoarthritis (OA). Eligible participants (n = 71) with early medial knee OA (Kellgren-Lawrence grade I or II) were randomized to either walking exercise or gait retraining group. Knee loading-related parameters including KAM, KAAI and KFM were measured before and after 6-week gait retraining. We also examined clinical outcomes including visual analog pain scale (VASP) and Knee Injury and Osteoarthritis Outcome Score (KOOS) at each time point. After gait retraining, KAM1 and VASP were significantly reduced (both Ps < 0.001) and KOOS significantly improved (p = 0.004) in the gait retraining group, while these parameters remained similar in the walking exercise group (Ps ≥ 0.448). However, KAM2, KAAI and KFM did not change in both groups across time (Ps ≥ 0.120). A six-week sensor-based gait retraining, compared with walking exercise, was an effective intervention to lower medial knee loading, relieve knee pain and improve symptoms for patients with early medial knee OA.
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- 2021
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24. Sleep homeostasis, seizures, and cognition in children with focal epilepsy
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Maria H. Eriksson, Torsten Baldeweg, Ronit Pressler, Stewart G. Boyd, Reto Huber, J. Helen Cross, Bigna K. Bölsterli, and Samantha Y. S. Chan
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Developmental Neuroscience ,Pediatrics, Perinatology and Child Health ,Neurology (clinical) - Abstract
To investigate the link between sleep disruption and cognitive impairment in childhood epilepsy by studying the effect of epilepsy on sleep homeostasis, as reflected in slow-wave activity (SWA).We examined SWA from overnight EEG-polysomnography in 19 children with focal epilepsy (mean [SD] age 11 years 6 months [3 years], range 6 years 6 months-15 years 6 months; 6 females, 13 males) and 18 age- and sex-matched typically developing controls, correlating this with contemporaneous memory consolidation task scores, full-scale IQ, seizures, and focal interictal discharges.Children with epilepsy did not differ significantly from controls in overnight SWA decline (p = 0.12) or gain in memory performance with sleep (p = 0.27). SWA was lower in patients compared to controls in the first hour of non-rapid eye movement sleep (p = 0.021), although not in those who remained seizure-free (p = 0.26). Full-scale IQ did not correlate with measures of SWA in patients or controls. There was no significant difference in SWA measures between focal and non-focal electrodes.Overnight SWA decline is conserved in children with focal epilepsy and may underpin the preservation of sleep-related memory consolidation in this patient group. Reduced early-night SWA may reflect impaired or immature sleep homeostasis in those with a higher seizure burden.
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- 2022
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25. Measurement invariance of the Multidimensional Depression Assessment Scale (MDAS) across gender and ethnic groups of Asian, Caucasian, Black, and Hispanic
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H N, Cheung, Joanne M, Williams, Y S, Chan, and Stella W Y, Chan
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psychometrics ,validation ,Depressive Disorder, Major ,Psychometrics ,Depression ,Reproducibility of Results ,Hispanic or Latino ,culture ,measurement invariance ,Psychiatry and Mental health ,Clinical Psychology ,Surveys and Questionnaires ,depression ,Ethnicity ,Humans ,Factor Analysis, Statistical - Abstract
BackgroundMajor Depressive Disorder is a severe and highly disabling mental illness. Almost all self-reported questionnaires have overlooked the interpersonal symptoms of depression which are important across gender and culture. The Multidimensional Depression Assessment Scale (MDAS) developed by Cheung and Power (2012) entails comprehensive emotional, cognitive, somatic, and interpersonal subscales. It addresses the criticism that existing self-report depression scales might not cover sufficient phenomenological heterogeneity of depression. The current study aimed to evaluate the psychometric properties of the MDAS across gender and four major ethnic groups of Caucasian, Black, Asian and Hispanic, including reliability and concurrent validity against the Centre for Epidemiological Studies Depression Scale (CESsingle bondD) and Patients Health Questionnaire (PHQ-9). It also aimed to establish a stable factor structure across gender and ethnic groups and test the measurement invariance to enhance its potential for clinical use.MethodsA community sample of 3499 participants from four ethnic groups were recruited via online crowdsourcing sites of Qualtrics and Amazon M Turk. Each individual completed a demographic questionnaire, the MDAS, CESD and PHQ-9.ResultsThere was good internal consistency (Cronbach's alpha >0.90) and concurrent reliability across gender and ethnic groups. Strict measurement invariance was established for MDAS over a four-factor factor structure corresponding to the four subscales.ConclusionsThe MDAS showed good psychometric properties and measurement invariance of a four-factor structure, suggesting its potential to be used in clinical settings across gender and ethnic groups.LimitationsParticipants all answered the questionnaires in English, which could hinder cultural variations in their expression of symptoms.
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- 2022
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26. Walking with head-mounted virtual and augmented reality devices: Effects on position control and gait biomechanics.
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Zoe Y S Chan, Aislinn J C MacPhail, Ivan P H Au, Janet H Zhang, Ben M F Lam, Reed Ferber, and Roy T H Cheung
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Medicine ,Science - Abstract
What was once a science fiction fantasy, virtual reality (VR) technology has evolved and come a long way. Together with augmented reality (AR) technology, these simulations of an alternative environment have been incorporated into rehabilitation treatments. The introduction of head-mounted displays has made VR/AR devices more intuitive and compact, and no longer limited to upper-limb rehabilitation. However, there is still limited evidence supporting the use of VR and AR technology during locomotion, especially regarding the safety and efficacy relating to walking biomechanics. Therefore, the objective of this study is to explore the limitations of such technology through gait analysis. In this study, thirteen participants walked on a treadmill in normal, virtual and augmented versions of the laboratory environment. A series of spatiotemporal parameters and lower-limb joint angles were compared between conditions. The center of pressure (CoP) ellipse area (95% confidence ellipse) was significantly different between conditions (p = 0.002). Pairwise comparisons indicated a significantly greater CoP ellipse area for both the AR (p = 0.002) and VR (p = 0.005) conditions when compared to the normal laboratory condition. Furthermore, there was a significant difference in stride length (p0.082), except for maximum ankle plantarflexion (p = 0.001). These differences in CoP ellipse area indicate that users of head-mounted VR/AR devices had difficulty maintaining a stable position on the treadmill. Also, differences in the gait parameters suggest that users walked with an unusual gait pattern which could potentially affect the effectiveness of gait rehabilitation treatments. Based on these results, position guidance in the form of feedback and the use of specialized treadmills should be considered when using head-mounted VR/AR devices.
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- 2019
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27. Some Facts and Conjectures about Mandelbrot Polynomials.
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Neil J. Calkin, Eunice Y. S. Chan, and Robert M. Corless
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- 2021
28. Bohemian Upper Hessenberg Matrices.
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Eunice Y. S. Chan, Robert M. Corless, Laureano González-Vega, J. Rafael Sendra, Juana Sendra, and Steven E. Thornton
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- 2018
29. Bohemian Upper Hessenberg Toeplitz Matrices.
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Eunice Y. S. Chan, Robert M. Corless, Laureano González-Vega, J. Rafael Sendra, Juana Sendra, and Steven E. Thornton
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- 2018
30. A random walk through experimental mathematics.
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Eunice Y. S. Chan and Robert M. Corless
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- 2018
31. Fibonacci-mandelbrot polynomials and matrices.
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Eunice Y. S. Chan and Robert M. Corless
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- 2016
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32. Magnitude of COVID-19 deaths relative to other leading causes of death: a global analysis
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Eunice Y S Chan, Davy Cheng, and Janet Martin
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Causality ,Cause of Death ,Uncertainty ,Humans ,COVID-19 ,General Medicine ,Disease Outbreaks - Abstract
ObjectivesTo quantify the burden of death that COVID-19 contributes relative to the top three causes of death for all countries.DesignWe performed uncertainty analyses and created contour plots for COVID-19 mortality to place the number of COVID-19 deaths in context relative to the top three causes of death in each country, across a plausible range of values for two key parameters: case fatality rate and magnitude of under-reporting.SettingAll countries that have reported COVID-19 cases to the WHO and are included in the Global Burden of Disease Study by the Institute of Health Metrics and Evaluation.Main outcomes and measuresMonthly number of deaths caused by COVID-19 and monthly number of deaths caused by the top three causes of death for every country.ResultsFor countries that were particularly hard hit during the outbreak in 2020, most combinations of model parameters resulted in COVID-19 ranking within the top three causes of death. For countries not as hard hit on a per-capita basis, such as China and India, COVID-19 did not rank higher than the third leading cause of death at any combination of the model parameters within the given ranges. Up-to-date ranking of COVID-19 deaths relative to the top three causes of death for all countries globally is provided in an interactive online application.ConclusionsEstimating the country-level burden of death that COVID-19 contributes relative to the top three causes of death is feasible through contour graphs, even when the actual number of deaths or cases is unknown. This method can help convey importance by placing the magnitude of COVID-related deaths in context relative to more familiar causes of death by communicating when COVID-related deaths rank among the top three causes of death.
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- 2022
33. Transmission of 38GHz Millimeter Wave Signals through Radio-Over-Fiber Systems.
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Y. S. Chan, Bin Luo, and Ling Chuen Ong
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- 2008
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34. Measurement agreement between a newly developed sensing insole and traditional laboratory-based method for footstrike pattern detection in runners.
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Roy T H Cheung, Winko W An, Ivan P H Au, Janet H Zhang, Zoe Y S Chan, Alfred Man, Fannie O Y Lau, Melody K Y Lam, K K Lau, C Y Leung, N W Tsang, Louis K Y Sze, and Gilbert W K Lam
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Medicine ,Science - Abstract
This study introduced a novel but simple method to continuously measure footstrike patterns in runners using inexpensive force sensors. Two force sensing resistors were firmly affixed at the heel and second toe of both insoles to collect the time signal of foot contact. A total of 109 healthy young adults (42 males and 67 females) were recruited in this study. They ran on an instrumented treadmill at 0°, +10°, and -10° inclinations and attempted rearfoot, midfoot, and forefoot landings using real time visual biofeedback. Intra-step strike index and onset time difference between two force sensors were measured and analyzed with univariate linear regression. We analyzed 25,655 footfalls and found that onset time difference between two sensors explained 80-84% of variation in the prediction model of strike index (R-squared = 0.799-0.836, p
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- 2017
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35. Efficacy and Safety of an Extravascular Implantable Cardioverter-Defibrillator
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Paul, Friedman, Francis, Murgatroyd, Lucas V A, Boersma, Jaimie, Manlucu, David, O'Donnell, Bradley P, Knight, Nicolas, Clémenty, Christophe, Leclercq, Anish, Amin, Béla P, Merkely, Ulrika M, Birgersdotter-Green, Joseph Y S, Chan, Mauro, Biffi, Reinoud E, Knops, Greg, Engel, Ignacio, Muñoz Carvajal, Laurence M, Epstein, Venkata, Sagi, Jens B, Johansen, Maciej, Sterliński, Clemens, Steinwender, Troy, Hounshell, Richard, Abben, Amy E, Thompson, Christopher, Wiggenhorn, Sarah, Willey, Ian, Crozier, Sergio, Thal, Cardiology, and ACS - Heart failure & arrhythmias
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Treatment Outcome ,Electric Countershock ,Humans ,Arrhythmias, Cardiac ,General Medicine ,Prospective Studies ,Defibrillators, Implantable - Abstract
BACKGROUND: The extravascular implantable cardioverter-defibrillator (ICD) has a single lead implanted substernally to enable pause-prevention pacing, antitachycardia pacing, and defibrillation energy similar to that of transvenous ICDs. The safety and efficacy of extravascular ICDs are not yet known. METHODS: We conducted a prospective, single-group, nonrandomized, premarket global clinical study involving patients with a class I or IIa indication for an ICD, all of whom received an extravascular ICD system. The primary efficacy end point was successful defibrillation at implantation. The efficacy objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients with successful defibrillation was greater than 88%. The primary safety end point was freedom from major system- or procedure-related complications at 6 months. The safety objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients free from such complications was greater than 79%. RESULTS: A total of 356 patients were enrolled, 316 of whom had an implantation attempt. Among the 302 patients in whom ventricular arrhythmia could be induced and who completed the defibrillation testing protocol, the percentage of patients with successful defibrillation was 98.7% (lower boundary of the one-sided 97.5% confidence interval [CI], 96.6%; P
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- 2022
36. The need for learning bioethics and law for biology students
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Brian A. Whitton, Gilbert Y. S. Chan, and Aaron Hin-tat Chan
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Coronavirus disease 2019 (COVID-19) ,education ,05 social sciences ,Biosecurity ,050301 education ,050109 social psychology ,Bioethics ,humanities ,Education ,Undergraduate curriculum ,Law ,0501 psychology and cognitive sciences ,General Agricultural and Biological Sciences ,China ,0503 education - Abstract
Although the creation in 2018 of a pair of genome-edited HIV-resistant twins in China caused widespread condemnation, we question whether the law and ethics relevant to such cases are dealt with ad...
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- 2020
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37. The role of botulinum toxin A in the management of different types of excessive gingival display: a systematic review
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Felicity Lam and Michael Y. S. Chan
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Gingiva ,Humans ,Prospective Studies ,Botulinum Toxins, Type A ,Esthetics, Dental ,General Dentistry ,Smiling - Abstract
Background An aesthetic smile displays a symmetrical 2 mm or less of gingival tissue. A smile with over 3 mm of gingival display can be deemed socially unaesthetic, impacting on a patient's psychosocial status. This literature review aimed to explore the role of botulinum toxin A as a treatment modality for different types of excessive gingival display (EGD) and appropriate treatment protocols.Methods A systematic search of the literature dating from 1980 onwards was conducted using electronic databases (Medline, Scopus and Web of Science). The Fowkes and Fulton quality assessment was undertaken to review the level of bias.Results Nine prospective studies were assessed for the number and site of injections, the unit dosage, the reconstitution and the improvement of EGD. Guidelines for treatment of EGD were constructed for operator consideration.Conclusions The data from this study elucidated that botulinum toxin is an effective treatment for all types of EGD caused by hyperfunctional smile muscles. It can be regarded as a safe treatment that reversibly improves facial aesthetics in patients suffering from gummy smile due to hyperactive musculature. Botulinum toxin was confirmed to be useful as a diagnostic tool and palliative treatment, as well as an adjunctive therapy in the treatment of a gummy smile.
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- 2022
38. Teaching Programming for Mathematical Scientists
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Jack Betteridge, Eunice Y. S. Chan, Robert M. Corless, James H. Davenport, and James Grant
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- 2022
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39. Morphometric Analysis of Human Embryonic Stem Cell-Derived Ventricular Cardiomyocytes: Determining the Maturation State of a Population by Quantifying Parameters in Individual Cells
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Harvey Y. S. Chan, Wendy Keung, Ronald A. Li, Andrew L. Miller, and Sarah E. Webb
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Internal medicine ,RC31-1245 - Abstract
Quantitative methods were established to determine the level of maturation of human embryonic stem cell-derived ventricular cardiomyocytes (hESC-vCMs) that were treated with different metabolic stimulants (i.e., isoproterenol and oleic acid) during early differentiation. Cells were double-immunolabeled with α-actinin and COX IV antibodies, to label the myofibrils and mitochondria, respectively, after which images were acquired via confocal microscopy. In order to determine the extent of differentiation, image analysis protocols were then used to quantify cell shape and area, as well as the degree of myofibrillar organization and intercalation of mitochondria between the myofibrils within the cells. We demonstrated that oleic acid or isoproterenol alone, or a combination of the two, induced a more elongated hESC-vCM phenotype than the untreated controls. In addition, cells treated with isoproterenol alone exhibited a similar level of myofibrillar organization as the controls, but those treated with oleic acid with/without isoproterenol exhibited a more organized (parallel) orientation of myofibrils. The combined isoproterenol/oleic acid treatment also resulted in enhanced intercalation of mitochondria between the myofibrils. We suggest that these quantitative morphometric methods might serve as simple and effective tools that can be utilized in the determination of the level of structural maturation of hESC-vCMs.
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- 2015
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40. The changing role of BIM-facilitated facilities management in the post-COVID era: A systematic literature review
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P Ma and I Y S Chan
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General Medicine ,General Chemistry - Abstract
COVID-19 has become a long-term pandemic and pushed the re-interpretation of normality. Fighting against the pandemic and building a new normal in the post-COVID era requires constant and innovative approaches. Building information modeling (BIM) facilitated facilities management (FM) has been advocated as a powerful method to overcome the huge public health-related challenges. However, studies investigating the role of BIM-facilitated FM in the pandemic era are fragmented, and holistic knowledge is limited. Research objectives of this study are twofold: (1) to identify varying FM requirements after the outbreak of COVID-19, (2) to investigate how BIM-facilitated FM copes with changing requests in the pandemic period. To achieve the objectives, a systematic literature review was conducted. Currently, FM tends to be public health-centric, and highly emphasized requirements encompass the flexibility of space transformation for emergency purpose, effective and sufficient ventilation, reliable biosecurity, and strict anti-infection management. Based on centralized database and visualized model, BIM-facilitated FM enables space optimization, simulation and prediction of infection risk, monitoring and managing equipment operation, and effective information management, which enhances both hard and soft FM. This paper sheds light on the applications and directions of future BIM-facilitated FM research in protecting public health in the post-COVID era.
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- 2022
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41. Treatment outcomes of T and natural-killer/T-cell lymphoma with ifosfamide, carboplatin and etoposide chemotherapy
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Tricia Tay, Nagavalli Somasundaram, Cindy Lim, Lay Poh Khoo, Allan Zhi Kai Goh, Yuh Shan Lee, Xin Liu, Miriam Tao, Richard Quek, Mohamad Farid, Eileen Poon, Jason Y. S. Chan, Esther W. Y. Chang, Valerie S. W. Yang, Yeow Tee Goh, Daryl Tan, Colin Diong, Nicholas F. Grigoropoulos, Chandramouli Nagarajan, Michelle Poon, Sanjay de Mel, Anand Jeyasekharan, Esther H. L. Chan, Joanne Lee, Yen Lin Chee, Soon Thye Lim, and Tiffany Tang
- Subjects
Cancer Research ,Treatment Outcome ,Oncology ,Lymphoma ,Antineoplastic Combined Chemotherapy Protocols ,Humans ,Ifosfamide ,Lymphoma, T-Cell ,Carboplatin ,Etoposide ,Retrospective Studies - Abstract
Contemporary data of peripheral T-cell lymphoma (PTCL) and natural-killer/T-cell lymphoma (NKTL) patients treated with ifosfamide, carboplatin and etoposide (ICE) are limited.We performed a retrospective analysis to estimate outcomes of ICE-treated PTCL and NKTL patients at three tertiary cancer centres in Singapore.Patients were identified through lymphoma databases from National Cancer Centre Singapore (NCCS), National University Hospital, Singapore (NUHS), and Singapore General Hospital (SGH). Responses and survival outcomes were determined from electronic medical records. A total of 75 patients with a median age of 50 were included. ICE was used as first-line treatment in 14 patients (19%) and as subsequent lines of treatment in 61 patients (81%). The overall response rates (ORR) for all patients was 63% (40% complete response [CR]). The ORR and CR in the first line were 86% and 64% respectively. At a median follow-up duration of 71.0 months, the median progression-free (PFS) and overall survival (OS) for all patients were 4.4 months (95%CI, 2.7-6.0) and 16 months (95%CI, 8.3-45.4) respectively.In summary, ICE showed high ORR but poor PFS in relapsed/refractory PTCL and NKTL. ORR of ICE in the first line setting appears better than real-world CHOP data and warrants further study.
- Published
- 2021
42. Recovery of Lactobacillus casei strain Shirota (LcS) from faeces of healthy Singapore adults after intake of fermented milk
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Q C Lau, Wei Wei Thwe Khine, X J Ang, Y-K Lee, Y S Chan, J K B Teo, S H Tan, S Y Quek, W Q Lee, and H T A Teo
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Microbiology (medical) ,Lactobacillus casei ,Gastrointestinal tract ,integumentary system ,biology ,Gut flora ,biology.organism_classification ,Microbiology ,Lactobacillus ,Ingestion ,Defecation ,Fermentation ,Food science ,Feces - Abstract
To validate survival of Lactobacillus casei strain Shirota (LcS) during passage through the gastrointestinal tract of healthy Singaporean young adults, 21 participants (18-25 years old) were asked to consume a 100 ml of fermented milk drink containing 1.0×108 cfu/ml of LcS daily for 14 days, and to maintain their dietary habit and life style. During and at the end of the ingestion period, both culture method (identity confirmed by ELISA) and 16s rRNA sequencing results revealed that viable LcS (7.27 and 7.64 log10 cfu/g of faeces at the ingestion period Day 7 and Day 14, respectively) and Lactobacillus could be recovered from the faeces of all the subjects. The viable LcS count from male and female were comparable for each time point. Before consumption (baseline) and 14 days after cessation of consumption of the fermented milk, LcS was not detected in most of the subjects. In this study condition, the composition of the major gut microbiota (>0.1% in relative abundance of genus) and characteristics of defaecation such as stool consistency and frequency of defecation did not change throughout the study before and after ingestion of LcS. LcS was able to survive passage through the gastrointestinal tract of Singapore adults without sustainable colonisation, but the effect of LcS on microbiota modulation, stool consistency and frequency was not observed under this study condition.
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- 2019
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43. The gelling effect of platelet-rich fibrin matrix when exposed to human tenocytes from the rotator cuff in small-diameter culture wells and the design of a co-culture device to overcome this phenomenon
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Y-S. Chan, W-L. Yeh, K-F. Lei, A. C-Y. Chen, K-Y. Hsu, C-H. Chiu, and P. Chen
- Subjects
030222 orthopedics ,Small diameter ,Materials science ,Research ,Fibrin matrix ,Rotator Cuff Tears ,Platelet-Rich Fibrin Matrix ,030229 sport sciences ,Matrix (biology) ,Platelet-rich fibrin ,Tenocytes ,Co-Culture ,Gelling Effect ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,medicine ,Orthopedics and Sports Medicine ,Surgery ,Rotator cuff ,Biomedical engineering - Abstract
Objectives Platelet-rich fibrin matrix (PRFM) has been proved to enhance tenocyte proliferation but has mixed results when used during rotator cuff repair. The optimal PRFM preparation protocol should be determined before clinical application. To screen the best PRFM to each individual’s tenocytes effectively, small-diameter culture wells should be used to increase variables. The gelling effect of PRFM will occur when small-diameter culture wells are used. A co-culture device should be designed to avoid this effect. Methods Tenocytes harvested during rotator cuff repair and blood from a healthy volunteer were used. Tenocytes were seeded in 96-, 24-, 12-, and six-well plates and co-culture devices. Appropriate volumes of PRFM, according to the surface area of each culture well, were treated with tenocytes for seven days. The co-culture device was designed to avoid the gelling effect that occurred in the small-diameter culture well. Cell proliferation was analyzed by water soluble tetrazolium-1 (WST-1) bioassay. Results The relative quantification (condition/control) of WST-1 assay on day seven revealed a significant decrease in tenocyte proliferation in small-diameter culture wells (96 and 24 wells) due to the gelling effect. PRFM in large-diameter culture wells (12 and six wells) and co-culture systems induced a significant increase in tenocyte proliferation compared with the control group. The gelling effect of PRFM was avoided by the co-culture device. Conclusion When PRFM and tenocytes are cultured in small-diameter culture wells, the gelling effect will occur and make screening of personalized best-fit PRFM difficult. This effect can be avoided with the co-culture device. Cite this article: C-H. Chiu, P. Chen, W-L. Yeh, A. C-Y. Chen, Y-S. Chan, K-Y. Hsu, K-F. Lei. The gelling effect of platelet-rich fibrin matrix when exposed to human tenocytes from the rotator cuff in small-diameter culture wells and the design of a co-culture device to overcome this phenomenon. Bone Joint Res 2019;8:216–223. DOI: 10.1302/2046-3758.85.BJR-2018-0258.R1.
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- 2019
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44. Algebraic linearizations of matrix polynomials
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Juana Sendra, Robert M. Corless, J. Rafael Sendra, Laureano Gonzalez-Vega, Eunice Y. S. Chan, and Universidad de Alcalá. Departamento de Física y Matemáticas. Unidad docente Matemáticas
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Numerical Analysis ,Algebra and Number Theory ,Matemáticas ,010102 general mathematics ,Companion matrix ,Linearization ,Numerical Analysis (math.NA) ,010103 numerical & computational mathematics ,01 natural sciences ,Combinatorics ,Matrix (mathematics) ,Matrix polynomials ,FOS: Mathematics ,Discrete Mathematics and Combinatorics ,Component (group theory) ,Block upper Hessenberg ,Mathematics - Numerical Analysis ,65F99, 15A22 ,Geometry and Topology ,0101 mathematics ,Algebraic number ,Companion matrices ,Mathematics - Abstract
Part of this work was developed while R.M.Corless was visiting the University of Alcalá, in the frame of the project Giner de los Rios. We acknowledge the support of the Ontario Graduate Institution, the National Science & Engineering Research Council of Canada, the University of Alcalá, the Rotman Institute of Philosophy, the Ontario Research Centre of Computer Algebra, and Western Univ., We show how to construct linearizations of matrix polynomials za(z)d0+c0, a(z)b(z), a(z) +b(z)(when deg (b(z)), Ministerio de Economía y Competitividad
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- 2019
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45. Impact of COVID-19 on excess mortality, life expectancy, and years of life lost in the United States
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Davy Cheng, Janet Martin, and Eunice Y. S. Chan
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Male ,Viral Diseases ,Epidemiology ,Global Health ,Geographical locations ,Medical Conditions ,Cause of Death ,Medicine and Health Sciences ,Medicine ,Public and Occupational Health ,Child ,Cause of death ,Excess mortality ,Aged, 80 and over ,education.field_of_study ,Multidisciplinary ,Mortality rate ,Middle Aged ,Infectious Diseases ,Child, Preschool ,Female ,Research Article ,Adult ,2019-20 coronavirus outbreak ,Religious Faiths ,Coronavirus disease 2019 (COVID-19) ,Adolescent ,Death Rates ,Science ,Population ,Islam ,Life Expectancy ,Population Metrics ,Humans ,education ,Pandemics ,Aged ,Population Biology ,business.industry ,SARS-CoV-2 ,COVID-19 ,Infant ,Biology and Life Sciences ,Covid 19 ,United States ,Years of potential life lost ,Age Groups ,North America ,Life expectancy ,Population Groupings ,People and places ,business ,Demography - Abstract
This paper quantifies the net impact (direct and indirect effects) of the pandemic on the United States population in 2020 using three metrics: excess deaths, life expectancy, and total years of life lost. The findings indicate there were 375,235 excess deaths, with 83% attributable to direct, and 17% attributable to indirect effects of COVID-19. The decrease in life expectancy was 1.67 years, translating to a reversion of 14 years in historical life expectancy gains. Total years of life lost in 2020 was 7,362,555 across the USA (73% directly attributable, 27% indirectly attributable to COVID-19), with considerable heterogeneity at the individual state level.
- Published
- 2021
46. Validation of the 5-D Itch Scale in Three Ethnic Groups and Exploring Optimal Cutoff Values Using the Itch Numerical Rating Scale
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H. N. Cheung, Y. S. Chan, and N. H. Hsiung
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Adult ,Male ,General Immunology and Microbiology ,Psychometrics ,Article Subject ,Pruritus ,Reproducibility of Results ,General Medicine ,Severity of Illness Index ,General Biochemistry, Genetics and Molecular Biology ,eye diseases ,humanities ,Surveys and Questionnaires ,Ethnic and Racial Minorities ,parasitic diseases ,Ethnicity ,Quality of Life ,otorhinolaryngologic diseases ,Medicine ,Humans ,Female ,Self Report ,skin and connective tissue diseases ,Research Article - Abstract
Background. Chronic pruritus is a common and distressing condition that has serious emotional and psychosocial consequences. Due to its subjective nature, self-report questionnaires are widely implemented as cost-effective measures to gauge the severity of chronic pruritus. The current study is aimed at validating the 5-D itch scale in three ethnic groups—Black, Asian, and Hispanic—with the well-validated Itch Numerical Rating Scale (NRS) and Worst Itch NRS (WI-NRS) and developing its cutoff value using receiver operating characteristics (ROC) and inspection of the area under the curve (AUC) across ethnic groups. At the same time, it is aimed at comparing the concurrent prevalence of itch and depression in these populations, who often form ethnic minorities in many countries. The current study addresses the knowledge gap of cultural adaptation of the 5-D pruritus scale for greater usage. Methods. Community samples of three ethnic groups were recruited from an online platform of Qualtrics and administered the self-report questionnaires of Itch-NRS, 5-D itch scale, and Patient Health Questionnaire-9 (PHQ-9) to measure their pruritus domains, itch intensity, depression screening, and its severity. Informed consent was obtained from all participants. Subgroup analysis was conducted, including concurrent validity and cutoff values compared between each ethnic group. Concurrent prevalence of itch and depression was evaluated using the cutoff value of Itch-NRS and PHQ-9. Result. A total of 2323 participants were included in the study. A significant positive correlation ( p < 0.001 ) was found between the Itch-NRS, WI-NRS, and 5-D itch scale. The cutoff value of the 5-D itch scale was established for the three ethnic groups using ROC, with a cutoff value of Itch-NRS as a reference. Conclusions. The 5-D itch scale has demonstrated sound psychometric properties in three ethnic groups and is closely related to Itch-NRS. The analysis of the cutoff value of the 5-D itch scale suggests that different cutoff values should be considered to reduce the inflation of pruritus severity.
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- 2021
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47. A Fractal Eigenvector
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Neil J. Calkin, Eunice Y. S. Chan, Robert M. Corless, David J. Jeffrey, and Piers W. Lawrence
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General Mathematics ,FOS: Mathematics ,Dynamical Systems (math.DS) ,Mathematics - Dynamical Systems ,15A18, 05C50 - Abstract
The recursively-constructed family of Mandelbrot matrices $M_n$ for $n=1$, $2$, $\ldots$ have nonnegative entries (indeed just $0$ and $1$, so each $M_n$ can be called a binary matrix) and have eigenvalues whose negatives $-\lambda = c$ give periodic orbits under the Mandelbrot iteration, namely $z_k = z_{k-1}^2+c$ with $z_0=0$, and are thus contained in the Mandelbrot set. By the Perron--Frobenius theorem, the matrices $M_n$ have a dominant real positive eigenvalue, which we call $\rho_n$. This article examines the eigenvector belonging to that dominant eigenvalue and its fractal-like structure, and similarly examines (with less success) the dominant singular vectors of $M_n$ from the singular value decomposition., Comment: 20 pages; 15 figures
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- 2021
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48. Cross-sectional study on attitudes among general practitioners towards pneumococcal vaccination for middle-aged and elderly population in Hong Kong.
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Lancelot W H Mui, Alvin Y S Chan, Albert Lee, and John Lee
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Medicine ,Science - Abstract
OBJECTIVE: To study the attitudes among general practitioners towards pneumococcal vaccination for middle-aged (50-64) and elderly population (over 65) in Hong Kong and the factors affecting their decision to advise pneumococcal vaccination for those age groups. DESIGN: Cross-sectional study of general practitioners in private practice in Hong Kong. PARTICIPANTS: Members of Hong Kong Medical Association delivering general practice services in private sector. MEASURING TOOL: Self-administered questionnaire. MAIN OUTCOME MEASURES: Intention to recommend pneumococcal vaccination, barriers against pneumococcal vaccination. RESULTS: 53.4% of the respondents would actively recommend pneumococcal vaccination to elderly patients but only 18.8% would recommend for middle-aged patients. Consultation not related to pneumococcal vaccine was the main reason for not recommending pneumococcal vaccine (43.6%). Rarity of pneumonia in their daily practice was another reason with 68.4% of respondents attending five or less patients with pneumonia each year. In multivariate analysis, factors such as respondents would get vaccination when reaching age 50 (ORm 10.1), and attending 6 pneumonia cases or more per year (ORm 2.28) were found to be associated with increasing likelihood for recommending vaccination to the middle-aged. While concerns of marketing a product (ORm 0.41), consultation not related to vaccination (ORm 0.45) and limited time (ORm 0.38) were factors that reduced the likelihood. CONCLUSION: Public policy is needed to increase the awareness of impact of pneumococcal pneumonia and the availability of preventive measures.
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- 2013
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49. γδ T cell frequencies are altered in HIV positive pregnant South African women and are associated with preterm birth
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W Zhang, Shane A. Norris, Manu Vatish, Krithi Ravi, Charlene Akoto, Christina Y. S. Chan, and Joris Hemelaar
- Subjects
0301 basic medicine ,RNA viruses ,Maternal Health ,T-Lymphocytes ,HIV Infections ,C-C chemokine receptor type 6 ,Pathology and Laboratory Medicine ,Chemokine receptor ,White Blood Cells ,Labor and Delivery ,South Africa ,0302 clinical medicine ,Immunodeficiency Viruses ,Animal Cells ,Pregnancy ,Medicine and Health Sciences ,Public and Occupational Health ,Lymphocytes ,Pregnancy Complications, Infectious ,Multidisciplinary ,medicine.diagnostic_test ,T Cells ,Gestational age ,Obstetrics and Gynecology ,Receptors, Antigen, T-Cell, gamma-delta ,Flow Cytometry ,Vaccination and Immunization ,medicine.anatomical_structure ,Medical Microbiology ,Viral Pathogens ,Viruses ,Medicine ,Infectious diseases ,Premature Birth ,Female ,Cellular Types ,Pathogens ,Cohort study ,Research Article ,Adult ,Receptors, CCR6 ,T cell ,Science ,Immune Cells ,Immunology ,Antiretroviral Therapy ,Viral diseases ,Preterm Birth ,Peripheral blood mononuclear cell ,Microbiology ,Flow cytometry ,03 medical and health sciences ,Antiviral Therapy ,Retroviruses ,medicine ,Humans ,Microbial Pathogens ,Immunosuppression Therapy ,Blood Cells ,business.industry ,Lentivirus ,Organisms ,Biology and Life Sciences ,HIV ,Cell Biology ,medicine.disease ,Pregnancy Complications ,030104 developmental biology ,Birth ,HIV-1 ,Women's Health ,Preventive Medicine ,business ,Biomarkers ,030215 immunology - Abstract
Background Preterm birth is the leading cause of neonatal and child mortality worldwide. Maternal HIV infection and antiretroviral treatment (ART) increase the rate of preterm birth, but the underlying mechanisms remain unknown, limiting progress in prediction, prevention and treatment. While overall γδ T cell levels remain constant, acute HIV infection is associated with a depletion of the Vδ2 subset and an increase in the Vδ1 subset, which do not return to baseline with ART. γδ T cells have also been implicated in adverse pregnancy outcomes and we therefore investigated the potential association between maternal HIV infection, peripheral γδ T cell frequencies and preterm birth. Methods Study participants were HIV positive (n = 47) and HIV negative (n = 45) women enrolled in a prospective pregnancy cohort study at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa. Women were enrolled in early pregnancy and gestational age was accurately determined by first trimester ultrasound scan. Peripheral blood samples were collected in each trimester and peripheral blood mononuclear cells isolated. Frequencies of γδ T cells, Vδ1+ and Vδ2+ γδ T cell subsets, and CCR6 chemokine receptor expression were determined by flow cytometry. Results Total γδ T cell levels were similar between HIV positive and HIV negative women throughout pregnancy. However, in each trimester maternal HIV infection was associated with reduced levels of the Vδ2+ subset and increased levels of the Vδ1+ subset, leading to a reversal of the Vδ1/Vδ2 ratio. Timing of ART initiation among HIV positive women did not affect levels of γδ T cells, the Vδ1+ and Vδ2+ subsets, or the Vδ1/Vδ2 ratio. Importantly, preterm birth was associated with lower total γδ T cell levels in early pregnancy and γδ T cell frequencies were lowest in HIV positive women who delivered preterm. Moreover, in the first trimester the proportion of Vδ1+ T cells that were CCR6+ was significantly reduced in HIV+ women and women who delivered preterm, resulting in the lowest proportion of CCR6+ Vδ1 T cells in HIV positive women who delivered preterm. Conclusions Our findings suggest that altered γδ T cell frequencies may link maternal HIV infection and preterm birth. γδ T cell frequencies in early pregnancy may serve as predictive biomarkers to identify women at risk of delivering preterm.
- Published
- 2020
50. Conference abstract
- Author
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W Zhang, Shane A. Norris, Krithi Ravi, Christina Y. S. Chan, Manu Vatish, Joris Hemelaar, Charlene Akoto, and Chrystelle O. O. Tshivuila-Matala
- Subjects
Adult ,0301 basic medicine ,medicine.medical_specialty ,Immunology ,Human immunodeficiency virus (HIV) ,lcsh:Medicine ,HIV Infections ,Pathogenesis ,medicine.disease_cause ,Article ,South Africa ,03 medical and health sciences ,0302 clinical medicine ,Acquired immunodeficiency syndrome (AIDS) ,Pregnancy ,Immunity ,medicine ,Humans ,Lymphocytes ,Extreme Preterm Birth ,Pregnancy Complications, Infectious ,lcsh:Science ,skin and connective tissue diseases ,Multidisciplinary ,Obstetrics ,business.industry ,lcsh:R ,Innate lymphoid cell ,Infant, Newborn ,medicine.disease ,Immunity, Innate ,body regions ,Child mortality ,030104 developmental biology ,Infant, Extremely Premature ,Premature Birth ,Gestation ,lcsh:Q ,Female ,Pregnant Women ,business ,Biomarkers ,030217 neurology & neurosurgery - Abstract
Preterm birth is the leading cause of neonatal and child mortality worldwide. Globally, 1.4 million pregnant women are estimated to be living with HIV/AIDS, the majority of whom live in sub-Saharan Africa. Maternal HIV infection and antiretroviral treatment (ART) have been associated with increased rates of preterm birth, but the underlying mechanisms remain unknown. Acute HIV infection is associated with a rapid depletion of all three subsets of innate lymphoid cells (ILCs), ILC1s, ILC2s and ILC3s, which is not reversed by ART. ILCs have been found at the maternal–fetal interface and we therefore investigated the potential association between maternal HIV infection, peripheral ILC frequencies and preterm birth. In our study of pregnant South African women with accurately dated pregnancies, we show that maternal HIV infection is associated with reduced levels of all three ILC subsets. Preterm birth was also associated with lower levels of all three ILC subsets in early pregnancy. ILC frequencies were lowest in HIV positive women who experienced preterm birth. Moreover, ILC levels were reduced in pregnancies resulting in spontaneous onset of preterm labour and in extreme preterm birth (
- Published
- 2020
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