33 results on '"Tiffany Leung"'
Search Results
2. P658: Detection of variant parent-of-origin in diverse hereditary cancer syndromes using only the proband’s blood sample
- Author
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Kasmintan Schrader, Vahid Akbari, Vincent Hanlon, Tiffany Leung, Katherine Dixon, Kieran O’Neill, Alexandra Roston, Lilian Cordova, Karen Wong, Alshanee Sharma, Yaoqing Shen, Janine Senz, Yanni Wang, Daniel Chan, Alexandra Fok, Quan Hong, Jennifer Nuk, Robin Coope, Eric Chuah, Simon Chan, Hyun-Wu Lee, Steve Bilobram, Yongjun Zhao, Miruna Bala, Karen Mungall, Andy Mungall, Richard Moore, Dean Regier, Alice Virani, Louis Lefebvre, Fabio Feldman, Marco Marra, Sophie Sun, Stephen Yip, Peter Lansdorp, and Steven Jones
- Subjects
Genetics ,QH426-470 ,Medicine - Published
- 2024
- Full Text
- View/download PDF
3. Optimizing vaccine allocation for COVID-19 vaccines shows the potential role of single-dose vaccination
- Author
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Laura Matrajt, Julia Eaton, Tiffany Leung, Dobromir Dimitrov, Joshua T. Schiffer, David A. Swan, and Holly Janes
- Subjects
Science - Abstract
Most COVID-19 vaccines require two doses but a single dose provides partial protection, so it is unclear how best to prioritize vaccine distribution in the context of limited supply. Here, the authors show that campaigns in which some age groups receive one dose while others receive both doses may be optimal.
- Published
- 2021
- Full Text
- View/download PDF
4. Evaluating the Effectiveness of Social Distancing Interventions to Delay or Flatten the Epidemic Curve of Coronavirus Disease
- Author
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Laura Matrajt and Tiffany Leung
- Subjects
respiratory infections ,severe acute respiratory syndrome coronavirus 2 ,SARS-CoV-2 ,SARS ,COVID-19 ,2019 novel coronavirus disease ,Medicine ,Infectious and parasitic diseases ,RC109-216 - Abstract
By April 2, 2020, >1 million persons worldwide were infected with severe acute respiratory syndrome coronavirus 2. We used a mathematical model to investigate the effectiveness of social distancing interventions in a mid-sized city. Interventions reduced contacts of adults >60 years of age, adults 20–59 years of age, and children
- Published
- 2020
- Full Text
- View/download PDF
5. Optimizing one-dose and two-dose cholera vaccine allocation in outbreak settings: A modeling study.
- Author
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Tiffany Leung, Julia Eaton, and Laura Matrajt
- Subjects
Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundA global stockpile of oral cholera vaccine (OCV) was established in 2013 for use in outbreak response and are licensed as two-dose regimens. Vaccine availability, however, remains limited. Previous studies have found that a single dose of OCV may provide substantial protection against cholera.MethodsUsing a mathematical model with two age groups paired with optimization algorithms, we determine the optimal vaccination strategy with one and two doses of vaccine to minimize cumulative overall infections, symptomatic infections, and deaths. We explore counterfactual vaccination scenarios in three distinct settings: Maela, the largest refugee camp in Thailand, with high in- and out-migration; N'Djamena, Chad, a densely populated region; and Haiti, where departments are connected by rivers and roads.ResultsOver the short term under limited vaccine supply, the optimal strategies for all objectives prioritize one dose to the older age group (over five years old), irrespective of setting and level of vaccination coverage. As more vaccine becomes available, it is optimal to administer a second dose for long-term protection. With enough vaccine to cover the whole population with one dose, the optimal strategies can avert up to 30% to 90% of deaths and 36% to 92% of symptomatic infections across the three settings over one year. The one-dose optimal strategies can avert 1.2 to 1.8 times as many cases and deaths compared to the standard two-dose strategy.ConclusionsIn an outbreak setting, speedy vaccination campaigns with a single dose of OCV is likely to avert more cases and deaths than a two-dose pro-rata campaign under a limited vaccine supply.
- Published
- 2022
- Full Text
- View/download PDF
6. Protection afforded by previous Vibrio cholerae infection against subsequent disease and infection: A review.
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Tiffany Leung and Laura Matrajt
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
BackgroundCholera is an acute, diarrheal disease caused by Vibrio cholerae O1 or 139 that is associated with a high global burden.MethodsWe analyzed the estimated duration of immunity following cholera infection from available published studies. We searched PubMed and Web of Science for studies of the long-term immunity following cholera infection. We identified 22 eligible studies and categorized them as either observational, challenge, or serological.ResultsWe found strong evidence of protection at 3 years after infection in observational and challenge studies. However, serological studies show that elevated humoral markers of potential correlates of protection returned to baseline within 1 year. Additionally, a subclinical cholera infection may confer lower protection than a clinical one, as suggested by 3 studies that found that, albeit with small sample sizes, most participants with a subclinical infection from an initial challenge with cholera had a symptomatic infection when rechallenged with a homologous biotype.ConclusionsThis review underscores the need to elucidate potential differences in the protection provided by clinical and subclinical cholera infections. Further, more studies are warranted to bridge the gap between the correlates of protection and cholera immunity. Understanding the duration of natural immunity to cholera can help guide control strategies and policy.
- Published
- 2021
- Full Text
- View/download PDF
7. Facilitating credentialing and engagement of international physician-migrants during the COVID-19 crisis and beyond
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Tiffany Leung, Ewelina Biskup, and Dawn DeWitt
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brain drain ,credentialing ,international medical graduates ,licensure ,medical education ,mentorship ,Special situations and conditions ,RC952-1245 ,Public aspects of medicine ,RA1-1270 - Abstract
Context: Physicians who migrate globally face a daunting series of time-consuming, labor- and resource-intensive procedures to prove their clinical competency before being allowed to practice medicine in a new country. Issues: In this commentary, we describe licensing barriers faced by physician-migrants based on the authors' experiences, and reflect also on rapidly implemented measures to address COVID-19 pandemic related workforce shortages. We offer recommendations for potential reductions in bureaucratic regulatory barriers that prohibit mobilization of international medical graduate talent. Lessons learned: Licensing boards and authorities should strive for standardized, competency-based basic professional recognition. Professional medical societies are well-positioned to guide such competency-based recognition as a more organized, international collaborative effort across specialties. The COVID-19 pandemic facilitated cross-state and international licensing in some regions, highlighting a key opportunity: streamlining professional recognition requirements is achievable.
- Published
- 2020
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8. The Use of Virtual Reality in Enhancing Interdisciplinary Research and Education
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Tiffany Leung, Farhana Zulkernine, and Haruna Isah
- Subjects
learning ,vr systems ,interdisciplinary research and education ,virtual reality ,Information technology ,T58.5-58.64 ,Communication. Mass media ,P87-96 - Abstract
Virtual Reality (VR) is increasingly being recognized for its educational potential and as an effective way to convey new knowledge to people, it supports interactive and collaborative activities. Affordable VR powered by mobile technologies is opening a new world of opportunities that can transform the ways in which we learn and engage with others. This paper reports our study regarding the application of VR in stimulating interdisciplinary communication. It investigates the promises of VR in interdisciplinary education and research. The main contributions of this study are (i) literature review of theories of learning underlying the justification of the use of VR systems in education, (ii) taxonomy of the various types and implementations of VR systems and their application in supporting education and research, (iii) evaluation of educational applications of VR from a broad range of disciplines, (iv) investigation of how the learning process and learning outcomes are affected by VR systems, and (v) comparative analysis of VR and traditional methods of teaching in terms of quality of learning. This study seeks to inspire and inform interdisciplinary researchers and learners about the ways in which VR might support them and also VR software developers to push the limits of their craft.
- Published
- 2018
9. Infection-acquired versus vaccine-acquired immunity in an SIRWS model
- Author
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Tiffany Leung, Patricia T. Campbell, Barry D. Hughes, Federico Frascoli, and James M. McCaw
- Subjects
Infectious and parasitic diseases ,RC109-216 - Abstract
In some disease systems, the process of waning immunity can be subtle, involving a complex relationship between the duration of immunity—acquired either through natural infection or vaccination—and subsequent boosting of immunity through asymptomatic re-exposure. We present and analyse a model of infectious disease transmission where primary and secondary infections are distinguished to examine the interplay between infection and immunity. Additionally we allow the duration of infection-acquired immunity to differ from that of vaccine-acquired immunity to explore the impact on long-term disease patterns and prevalence of infection in the presence of immune boosting.Our model demonstrates that vaccination may induce cyclic behaviour, and the ability of vaccinations to reduce primary infections may not lead to decreased transmission. Where the boosting of vaccine-acquired immunity delays a primary infection, the driver of transmission largely remains primary infections. In contrast, if the immune boosting bypasses a primary infection, secondary infections become the main driver of transmission under a sufficiently long duration of immunity.Our results show that the epidemiological patterns of an infectious disease may change considerably when the duration of vaccine-acquired immunity differs from that of infection-acquired immunity. Our study highlights that for any particular disease and associated vaccine, a detailed understanding of the waning and boosting of immunity and how the duration of protection is influenced by infection prevalence are important as we seek to optimise vaccination strategies. Keywords: Infectious disease modelling, Vaccination, Waning immunity, Immune boosting
- Published
- 2018
- Full Text
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10. Culture-Dependent Bioprospecting of Bacterial Isolates From the Canadian High Arctic Displaying Antibacterial Activity
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Evangelos Marcolefas, Tiffany Leung, Mira Okshevsky, Geoffrey McKay, Emma Hignett, Jérémie Hamel, Gabriela Aguirre, Olivia Blenner-Hassett, Brian Boyle, Roger C. Lévesque, Dao Nguyen, Samantha Gruenheid, and Lyle Whyte
- Subjects
Arctic ,bioprospecting ,antibiotics ,secondary metabolites ,microbial cultivation ,Microbiology ,QR1-502 - Abstract
The goal of this study was to isolate, screen, and characterize Arctic microbial isolates from Expedition Fjord, Axel Heiberg Island, Nunavut, Canada capable of inhibiting the growth of foodborne and clinically relevant pathogens. Arctic bacteria were isolated from twelve different high Arctic habitats pertaining to active layer permafrost soil, saline spring sediments, lake sediments, and endoliths. This was achieved using (1) the cryo-iPlate, an innovative in situ cultivation device within active layer permafrost soil and (2) bulk plating of Arctic samples by undergraduate students that applied standard culturing methods. To mitigate the possibility of identifying isolates with already-known antibacterial activities, a cell-based dereplication platform was used. Ten out of the twelve Arctic habitats tested were found to yield cold-adapted isolates with antibacterial activity. Eight cold-adapted Arctic isolates were identified with the ability to inhibit the entire dereplication platform, suggesting the possibility of new mechanisms of action. Two promising isolates, initially cultured from perennial saline spring sediments and from active layer permafrost soil (Paenibacillus sp. GHS.8.NWYW.5 and Pseudomonas sp. AALPS.10.MNAAK.13, respectively), displayed antibacterial activity against foodborne and clinically relevant pathogens. Paenibacillus sp. GHS.8.NWYW.5 was capable of inhibiting methicillin resistant and susceptible Staphylococcus aureus (MRSA and MSSA), Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7. Pseudomonas sp. AALPS.10.MNAAK.13 was observed to have antagonistic activity against MRSA, MSSA, Acinetobacter baumanii, Enterococcus faecium, and Enterococcus faecalis. After whole genome sequencing and mining, the genome of Paenibacillus sp. GHS.8.NWYW.5 was found to contain seven putative secondary metabolite biosynthetic gene clusters that displayed low homology ( 0) to clusters identified within the genome of the type strain pertaining to the same species. These findings suggest that cold-adapted Arctic microbes may be a promising source of novel secondary metabolites for potential use in both industrial and medical settings.
- Published
- 2019
- Full Text
- View/download PDF
11. Mechanistic insight into the TH1-biased immune response to recombinant subunit vaccines delivered by probiotic bacteria-derived outer membrane vesicles.
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Joseph A Rosenthal, Chung-Jr Huang, Anne M Doody, Tiffany Leung, Kaho Mineta, Danielle D Feng, Elizabeth C Wayne, Nozomi Nishimura, Cynthia Leifer, Matthew P DeLisa, Susana Mendez, and David Putnam
- Subjects
Medicine ,Science - Abstract
Recombinant subunit vaccine engineering increasingly focuses on the development of more effective delivery platforms. However, current recombinant vaccines fail to sufficiently stimulate protective adaptive immunity against a wide range of pathogens while remaining a cost effective solution to global health challenges. Taking an unorthodox approach to this fundamental immunological challenge, we isolated the TLR-targeting capability of the probiotic E. coli Nissle 1917 bacteria (EcN) by engineering bionanoparticlate antigen carriers derived from EcN outer membrane vesicles (OMVs). Exogenous model antigens expressed by these modified bacteria as protein fusions with the bacterial enterotoxin ClyA resulted in their display on the surface of the carrier OMVs. Vaccination with the engineered EcN OMVs in a BALB/c mouse model, and subsequent mechanism of action analysis, established the EcN OMV's ability to induce self-adjuvanted robust and protective humoral and T(H)1-biased cellular immunity to model antigens. This finding appears to be strain-dependent, as OMV antigen carriers similarly engineered from a standard K12 E. coli strain derivative failed to generate a comparably robust antigen-specific TH1 bias. The results demonstrate that unlike traditional subunit vaccines, these biomolecularly engineered "pathogen-like particles" derived from traditionally overlooked, naturally potent immunomodulators have the potential to effectively couple recombinant antigens with meaningful immunity in a broadly applicable fashion.
- Published
- 2014
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12. The Influence of Memory on Visual Perception in Infants, Children, and Adults.
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Sagi Jaffe-Dax, Christine E. Potter, Tiffany Leung, Lauren L. Emberson, and Casey Lew-Williams
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- 2023
- Full Text
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13. Memory integration into visual perception through infancy, childhood, and adulthood.
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Sagi Jaffe-Dax, Christine E. Potter, Tiffany Leung, Casey Lew-Williams, and Lauren L. Emberson
- Published
- 2020
14. Telemedicine in internal medicine: A statement by the European Federation of Internal Medicine.
- Author
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Filomena, Pietrantonio, primary, Sebastian, Kuhn, additional, Kati, Kärberg, additional, Tiffany, Leung, additional, and Ismael, Said-Criado, additional
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- 2023
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15. Refining the genomic determinants underlying escape from X-chromosome inactivation
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Samantha Peeters, Tiffany Leung, Oriol Fornes, Rachelle A Farkas, Wyeth W Wasserman, and Carolyn J Brown
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Structural Biology ,Applied Mathematics ,Genetics ,Molecular Biology ,Computer Science Applications - Abstract
X-chromosome inactivation (XCI) epigenetically silences one X chromosome in every cell in female mammals. Although the majority of X-linked genes are silenced, in humans 20% or more are able to escape inactivation and continue to be expressed. Such escape genes are important contributors to sex differences in gene expression, and may impact the phenotypes of X aneuploidies; yet the mechanisms regulating escape from XCI are not understood. We have performed an enrichment analysis of transcription factor binding on the X chromosome, providing new evidence for enriched factors at the transcription start sites of escape genes. The top escape-enriched transcription factors were detected at the RPS4X promoter, a well-described human escape gene previously demonstrated to escape from XCI in a transgenic mouse model. Using a cell line model system that allows for targeted integration and inactivation of transgenes on the mouse X chromosome, we further assessed combinations of RPS4X promoter and genic elements for their ability to drive escape from XCI. We identified a small transgenic construct of only 6 kb capable of robust escape from XCI, establishing that gene-proximal elements are sufficient to permit escape, and highlighting the additive effect of multiple elements that work together in a context-specific fashion.
- Published
- 2022
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- View/download PDF
16. A personal history of trauma and experience of secondary traumatic stress, vicarious trauma, and burnout in mental health workers: A systematic literature review
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Tiffany Leung, Fred Schmidt, and Christopher Mushquash
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Clinical Psychology ,Social Psychology - Abstract
Secondary traumatic stress (STS), vicarious trauma (VT), and burnout (BO) are work-related outcomes commonly ascribed to mental health workers, given their exposure to clients' traumatic experiences. It is theorized that a worker's own history of trauma increases the occurrence of these outcomes, through retraumatization/activation of threat cues during client interactions and overinvolvement with a client's progress. Given the inconsistencies in the literature and the ubiquity of trauma among workers, a systematic review was conducted to examine the association of personal trauma and the 3 related, but separate, work outcomes.A systematic search strategy was used across relevant research databases (Cochrane, JSTOR, PsycINFO, PubMed) for empirical studies conducted from 2000-2021. In accordance with PRISMA guidelines, a four-phase selection process was used, resulting in 39 studies identified meeting the inclusion criteria.A clear (positive) association between personal trauma history and STS and VT were identified, whereas mostly null findings were observed in regard to BO. The majority of studies were conducted in Western countries, adopted questionnaires as the primary means of data collection, and all but one were cross-sectional in design.In addition to a lack of diversity in study design, there were conceptual limitations to the research conducted (e.g., treating victims as a unitary group, neglecting the inclusion of mechanisms). To assist in moving the field forward, five research recommendations are outlined with the goal of creating greater clarity in the work-outcomes literature and increased nuance in how personal trauma is understood. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
- Published
- 2022
17. The influence of memory on visual perception in infants, children, and adults
- Author
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Sagi Jaffe-Dax, Christine Potter, Tiffany Leung, Lauren Emberson, and Casey Lew-Williams
- Subjects
genetic structures - Abstract
Perception is not an independent, in-the-moment event. Instead, perceiving involves integrating prior expectations with current observations. How does this ability develop from infancy through adulthood? We examined how prior visual experience shapes visual perception in infants, children, and adults. Using an identical task across age groups, we exposed participants to pairs of colorful stimuli and measured their ability to discriminate relative saturation levels. Results showed that adult participants were biased by previously-experienced exemplars, but exhibited weakened in-the-moment discrimination between different levels of saturation. In contrast, infants and children showed less influence of memory in their perception, and they actually outperformed adults in discriminating between current levels of saturation. Our findings suggest that as humans develop, their perception relies more on prior experience and less on current observation.
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- 2022
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18. Optimizing one-dose and two-dose cholera vaccine allocation in outbreak settings: A modeling study
- Author
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Tiffany Leung, Laura Matrajt, and Julia Eaton
- Subjects
Outbreak response ,education.field_of_study ,Immunization Programs ,business.industry ,Population ,Public Health, Environmental and Occupational Health ,Administration, Oral ,Outbreak ,Cholera Vaccines ,medicine.disease ,Cholera ,Disease Outbreaks ,Vaccination ,Infectious Diseases ,Age groups ,Child, Preschool ,Environmental health ,Vaccination coverage ,medicine ,Humans ,education ,Cholera vaccine ,business ,Aged - Abstract
Background A global stockpile of oral cholera vaccine (OCV) was established in 2013 for use in outbreak response and are licensed as two-dose regimens. Vaccine availability, however, remains limited. Previous studies have found that a single dose of OCV may provide substantial protection against cholera. Methods Using a mathematical model with two age groups paired with optimization algorithms, we determine the optimal vaccination strategy with one and two doses of vaccine to minimize cumulative overall infections, symptomatic infections, and deaths. We explore counterfactual vaccination scenarios in three distinct settings: Maela, the largest refugee camp in Thailand, with high in- and out-migration; N’Djamena, Chad, a densely populated region; and Haiti, where departments are connected by rivers and roads. Results Over the short term under limited vaccine supply, the optimal strategies for all objectives prioritize one dose to the older age group (over five years old), irrespective of setting and level of vaccination coverage. As more vaccine becomes available, it is optimal to administer a second dose for long-term protection. With enough vaccine to cover the whole population with one dose, the optimal strategies can avert up to 30% to 90% of deaths and 36% to 92% of symptomatic infections across the three settings over one year. The one-dose optimal strategies can avert 1.2 to 1.8 times as many cases and deaths compared to the standard two-dose strategy. Conclusions In an outbreak setting, speedy vaccination campaigns with a single dose of OCV is likely to avert more cases and deaths than a two-dose pro-rata campaign under a limited vaccine supply.
- Published
- 2021
- Full Text
- View/download PDF
19. Optimizing vaccine allocation for COVID-19 vaccines: potential role of single-dose vaccination
- Author
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Joshua T. Schiffer, David A. Swan, Dobromir T. Dimitrov, Holly Janes, Julia Eaton, Laura Matrajt, and Tiffany Leung
- Subjects
COVID-19 Vaccines ,Coronavirus disease 2019 (COVID-19) ,Basic Reproduction Number ,Dose-Response Relationship, Immunologic ,Psychological intervention ,Context (language use) ,Article ,High transmission ,Environmental health ,Pandemic ,Humans ,Computational models ,Medicine ,Disease burden ,Vaccines ,SARS-CoV-2 ,business.industry ,Vaccination ,Immunity ,COVID-19 ,Hospitalization ,Intensive Care Units ,Viral infection ,Optimal allocation ,business - Abstract
Most COVID-19 vaccines require two doses, however with limited vaccine supply, policymakers are considering single-dose vaccination as an alternative strategy. Using a mathematical model combined with optimization algorithms, we determined optimal allocation strategies with one and two doses of vaccine under various degrees of viral transmission. Under low transmission, we show that the optimal allocation of vaccine vitally depends on the single-dose efficacy. With high single-dose efficacy, single-dose vaccination is optimal, preventing up to 22% more deaths than a strategy prioritizing two-dose vaccination for older adults. With low or moderate single-dose efficacy, mixed vaccination campaigns with complete coverage of older adults are optimal. However, with modest or high transmission, vaccinating older adults first with two doses is best, preventing up to 41% more deaths than a single-dose vaccination given across all adult populations. Our work suggests that it is imperative to determine the efficacy and durability of single-dose vaccines, as mixed or single-dose vaccination campaigns may have the potential to contain the pandemic much more quickly., Most COVID-19 vaccines require two doses but a single dose provides partial protection, so it is unclear how best to prioritize vaccine distribution in the context of limited supply. Here, the authors show that campaigns in which some age groups receive one dose while others receive both doses may be optimal.
- Published
- 2021
- Full Text
- View/download PDF
20. Vaccine optimization for COVID-19, who to vaccinate first?
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Tiffany Leung, Elizabeth R. Brown, Laura Matrajt, and Julia Eaton
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Risk ,Prioritization ,COVID-19 Vaccines ,Coronavirus disease 2019 (COVID-19) ,Population ,Economic shortage ,Models, Biological ,Article ,03 medical and health sciences ,0302 clinical medicine ,Age groups ,Environmental health ,Pandemic ,Humans ,Medicine ,030212 general & internal medicine ,Epidemics ,education ,Pandemics ,Research Articles ,030304 developmental biology ,0303 health sciences ,education.field_of_study ,Multidisciplinary ,Optimization algorithm ,SARS-CoV-2 ,business.industry ,Vaccination ,Age Factors ,COVID-19 ,SciAdv r-articles ,Hospitalization ,Coronavirus ,Vaccination coverage ,business ,Algorithms ,Research Article - Abstract
The optimal use of COVID-19 vaccine depends mainly on how efficacious the vaccine is and how many doses are available., Vaccines, when available, will likely become our best tool to control the COVID-19 pandemic. Even in the most optimistic scenarios, vaccine shortages will likely occur. Using an age-stratified mathematical model paired with optimization algorithms, we determined optimal vaccine allocation for four different metrics (deaths, symptomatic infections, and maximum non-ICU and ICU hospitalizations) under many scenarios. We find that a vaccine with effectiveness ≥50% would be enough to substantially mitigate the ongoing pandemic, provided that a high percentage of the population is optimally vaccinated. When minimizing deaths, we find that for low vaccine effectiveness, irrespective of vaccination coverage, it is optimal to allocate vaccine to high-risk (older) age groups first. In contrast, for higher vaccine effectiveness, there is a switch to allocate vaccine to high-transmission (younger) age groups first for high vaccination coverage. While there are other societal and ethical considerations, this work can provide an evidence-based rationale for vaccine prioritization.
- Published
- 2020
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21. Immune responses to cholera following natural infection: a review
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Tiffany Leung and Laura Matrajt
- Subjects
Innate immune system ,business.industry ,medicine.disease_cause ,medicine.disease ,Cholera ,Serology ,Immune system ,Immunity ,Vibrio cholerae ,Immunology ,Medicine ,Observational study ,business ,Subclinical infection - Abstract
Cholera is an acute, diarrheal disease caused by Vibrio cholerae O1 or 139 that is associated with a high global burden. In this review, we identify the estimated duration of immunity following cholera infection with and without clinical symptoms from available published studies. We searched Pubmed and Web of Science for studies examining the long-term infection-acquired immunity against cholera infection. We identified 22 eligible studies and categorized them as either observational, challenge, or serological. We observed in observational and challenge studies that at three years, there is strong evidence of protection. However, serological studies show that elevated humoral markers returned to baseline within one year. Although with small sample sizes, three studies found that most participants with a subclinical infection from an initial challenge with cholera had a symptomatic infection when rechallenged with a homologous biotype, suggesting that a subclinical cholera infection may confer lower protection than a clinical one. This review underscores the need to elucidate potential differences in the protection provided by clinical and subclinical cholera infections. Further, more studies are warranted to bridge the gap between the correlates of protection and cholera immunity. Understanding the duration of natural immunity to cholera can help guide control strategies and policy.
- Published
- 2020
- Full Text
- View/download PDF
22. DISCREPANCY BETWEEN FIRST IMPRESSION AND SOCIAL DESCRIPTION, AND ITS EFFECT ON PEOPLE’S ATTITUDE
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Hiu Tung Tiffany Leung and Joanna Wincenciak
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Experimental psychology ,General Arts and Humanities ,media_common.quotation_subject ,Personal relationship ,Novelty ,General Social Sciences ,Impression formation ,Cognition ,Vignette ,Perception ,Psychology ,Social psychology ,Competence (human resources) ,media_common - Abstract
Purpose: Both facial appearance and behaviors could respectively contribute to impression formation towards an indi- vidual. However, when there is congruence between information decoded from facial appearance and behaviors which may determine impression in different ways, effect of both factors will be altered. This study aimed to investigate the discrepancy between the information carried by the face, i.e. facial trustworthiness and social description, and how these two factors influence individuals’ attitude towards a newly-met person, and their judgment with regard to warmth and competence.\ud \ud \ud Methodology: An experiment was conducted, asking participants to rate their impression in terms of warmth and compe- tence towards an individual whose facial appearance was manipulated either to be trustworthy or untrustworthy, and whose behavior was described in a short vignette.\ud \ud \ud Main Findings: The results indicated that social description had a significant influence on both warmth and competence impressions. Facial trustworthiness had no effect. It was also discovered that competence was found to be generally judged more positive than warmth, which implied judgment of warmth was made more reservedly.\ud \ud \ud Implications: The study would serve as an antecedent to further investigation on managing people’s impression towards oneself, in which such management aids in developing and maintaining positive personal relationship amongst human beings. The study will demonstrate a new vision to the researchers in cognition and perception on exploring approaches to define the mechanism involved in impression formation or attitude.\ud \ud \ud Novelty: Researchers trust that currently there is still no related research that would determine the direction and strength of effect from facial trustworthiness and social description.
- Published
- 2019
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23. Culture-Dependent Bioprospecting of Bacterial Isolates From the Canadian High Arctic Displaying Antibacterial Activity
- Author
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Roger C. Levesque, Jérémie Hamel, Brian Boyle, Dao Nguyen, Geoffrey McKay, Tiffany Leung, Evangelos Marcolefas, Samantha Gruenheid, Gabriela Aguirre, Lyle G. Whyte, Mira Okshevsky, Emma Hignett, and Olivia Blenner-Hassett
- Subjects
Microbiology (medical) ,bioprospecting ,lcsh:QR1-502 ,Secondary metabolite ,Microbiology ,Enterococcus faecalis ,antibiotics ,lcsh:Microbiology ,03 medical and health sciences ,Arctic ,medicine ,microbial cultivation ,030304 developmental biology ,Original Research ,0303 health sciences ,biology ,030306 microbiology ,secondary metabolites ,Pseudomonas ,Acinetobacter ,biology.organism_classification ,Salmonella enterica ,Bacteria ,Enterococcus faecium ,medicine.drug - Abstract
The goal of this study was to isolate, screen, and characterize Arctic microbial isolates from Expedition Fjord, Axel Heiberg Island, Nunavut, Canada capable of inhibiting the growth of foodborne and clinically relevant pathogens. Arctic bacteria were isolated from twelve different high Arctic habitats pertaining to active layer permafrost soil, saline spring sediments, lake sediments, and endoliths. This was achieved using (1) the cryo-iPlate, an innovative in situ cultivation device within active layer permafrost soil and (2) bulk plating of Arctic samples by undergraduate students that applied standard culturing methods. To mitigate the possibility of identifying isolates with already-known antibacterial activities, a cell-based dereplication platform was used. Ten out of the twelve Arctic habitats tested were found to yield cold-adapted isolates with antibacterial activity. Eight cold-adapted Arctic isolates were identified with the ability to inhibit the entire dereplication platform, suggesting the possibility of new mechanisms of action. Two promising isolates, initially cultured from perennial saline spring sediments and from active layer permafrost soil (Paenibacillus sp. GHS.8.NWYW.5 and Pseudomonas sp. AALPS.10.MNAAK.13, respectively), displayed antibacterial activity against foodborne and clinically relevant pathogens. Paenibacillus sp. GHS.8.NWYW.5 was capable of inhibiting methicillin resistant and susceptible Staphylococcus aureus (MRSA and MSSA), Listeria monocytogenes, Salmonella enterica and Escherichia coli O157:H7. Pseudomonas sp. AALPS.10.MNAAK.13 was observed to have antagonistic activity against MRSA, MSSA, Acinetobacter baumanii, Enterococcus faecium, and Enterococcus faecalis. After whole genome sequencing and mining, the genome of Paenibacillus sp. GHS.8.NWYW.5 was found to contain seven putative secondary metabolite biosynthetic gene clusters that displayed low homology ( 0) to clusters identified within the genome of the type strain pertaining to the same species. These findings suggest that cold-adapted Arctic microbes may be a promising source of novel secondary metabolites for potential use in both industrial and medical settings.
- Published
- 2019
- Full Text
- View/download PDF
24. Periodic solutions in an SIRWS model with immune boosting and cross-immunity
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James M. McCaw, Federico Frascoli, Barry D. Hughes, and Tiffany Leung
- Subjects
Immunity, Herd ,0301 basic medicine ,Statistics and Probability ,Protective immunity ,Bordetella pertussis ,Bordetella parapertussis ,Whooping Cough ,030106 microbiology ,Population ,Immunization, Secondary ,Cross immunity ,Cross Reactions ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Immune system ,Humans ,Applied mathematics ,Quantitative Biology - Populations and Evolution ,education ,Boosting (doping) ,education.field_of_study ,General Immunology and Microbiology ,biology ,Applied Mathematics ,Populations and Evolution (q-bio.PE) ,Models, Immunological ,General Medicine ,biology.organism_classification ,030104 developmental biology ,FOS: Biological sciences ,Modeling and Simulation ,Immunology ,General Agricultural and Biological Sciences ,Disease transmission - Abstract
Incidence of whooping cough, an infection caused by Bordetella pertussis and Bordetella parapertussis, has been on the rise since the 1980s in many countries. Immunological interactions, such as immune boosting and cross-immunity between pathogens, have been hypothesised to be important drivers of epidemiological dynamics. We present a two-pathogen model of transmission which examines how immune boosting and cross-immunity can influence the timing and severity of epidemics. We use a combination of numerical simulations and bifurcation techniques to study the dynamical properties of the system, particularly the conditions under which stable periodic solutions are present. We derive analytic expressions for the steady state of the single-pathogen model, and give a condition for the presence of periodic solutions. A key result from our two-pathogen model is that, while studies have shown that immune boosting at relatively strong levels can independently generate periodic solutions, cross-immunity allows for the presence of periodic solutions even when the level of immune boosting is weak. Asymmetric cross-immunity can produce striking increases in the incidence and period. Our study underscores the importance of developing a better understanding of the immunological interactions between pathogens in order to improve model-based interpretations of epidemiological data., 17 pages, 7 figures
- Published
- 2016
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25. Rabies Vaccination Targets for Stray Dog Populations
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Tiffany Leung and Stephen Davis
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Veterinary medicine ,040301 veterinary sciences ,030231 tropical medicine ,Population ,Culling ,Biology ,0403 veterinary science ,03 medical and health sciences ,infectious disease modeling ,0302 clinical medicine ,dog rabies ,Animal welfare ,Environmental health ,parasitic diseases ,medicine ,education ,Original Research ,education.field_of_study ,General Veterinary ,Mortality rate ,Zoonosis ,04 agricultural and veterinary sciences ,zoonosis ,medicine.disease ,Vaccination ,Rabies ,Veterinary Science ,canine rabies ,Basic reproduction number ,mathematical model - Abstract
The role of stray dogs in the persistence of domestic dog rabies, and whether removal of such dogs is beneficial, remain contentious issues for control programs seeking to eliminate rabies. While a community might reach the WHO vaccination target of 70% for dogs that can be handled, the stray or neighborhood dogs that are too wary of humans to be held are a more problematic population to vaccinate. So what needs to be done? Here we present a method to estimate vaccination targets for stray dogs when the dog population is made up of stray, free-roaming and confined dogs, where the latter two types are considered to have an identifiable owner. The control effort required for stray dogs is determined by the type reproduction number, T_1, the number of stray dogs infected by one rabid stray dog either directly or via any chain of infection involving owned dogs. Like the basic reproduction number R_0 for single host populations, T_1 determines the vaccination effort required to control the spread of disease when control is targeted at one host type, and there are a mix of host types. The application of T_1 to rabies in mixed populations of stray and owned dogs is novel. We show that the outcome is sensitive to the vaccination coverage in the owned dog population, such that if vaccination rates of owned dogs were too low then no control effort targeting stray dogs is able to control or eliminate rabies. The required vaccination level also depends on the composition of the dog population, where a high proportion of either stray or free-roaming dogs implies unrealistically high vaccination levels are required to prevent rabies. We find that the required control effort is less sensitive to continuous culling that increases the death rate of stray dogs than to changes in the carrying capacity of the stray dog population.
- Published
- 2017
26. Lack of association between dopamine-β hydroxylase gene and a history of suicide attempt in schizophrenia
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Maria Tampakeras, Aaron S. Howe, Clement C. Zai, John Strauss, Tiffany Leung, Ali Bani-Fatemi, Vincenzo De Luca, Renan P. Souza, and James L. Kennedy
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Adult ,Male ,Candidate gene ,Poison control ,Suicide, Attempted ,Dopamine beta-Hydroxylase ,Linkage Disequilibrium ,Genetics ,Humans ,Medicine ,Genetic Predisposition to Disease ,Alleles ,Genetic Association Studies ,Biological Psychiatry ,Genetics (clinical) ,Psychiatric genetics ,Demography ,Genetic association ,Principal Component Analysis ,Suicide attempt ,business.industry ,Haplotype ,Amplicon Size ,Psychiatry and Mental health ,Haplotypes ,Genetic marker ,Schizophrenia ,Female ,business - Abstract
OBJECTIVE(S): In the present study, we examined whether there was an association between dopamine-β hydroxylase (DBH) promoter polymorphisms (a 5'-ins/del and a GTn repeats) and a history of suicide attempt in 223 chronic schizophrenia individuals using statistical and molecular analyses. Within the genetic association study design, we compared the statistical haplotype phase with the molecular phase produced by the amplicon size analysis. MATERIALS AND METHODS: The two DBH polymorphisms were analysed using the Applied Biosystem 3130 and the statistical analyses were carried out using UNPHASED v.3.1.5 and PHASE v.2.1.1 to determine the haplotype frequencies and infer the phase in each patient. Then, DBH polymorphisms were incorporated into the Haploscore analysis to test the association with a history of suicide attempt. RESULTS: In our sample, 62 individuals had a history of suicide attempt. There was no association between DBH polymorphisms and a history of suicide attempt across the different analytical strategies applied. There was no significant difference between the haplotype frequencies produced by the amplicon size analysis and statistical analytical strategies. However, some of the haplotype pairs inferred in the PHASE analysis were inconsistent with the molecular haplotype size measured by the ABI 3130. CONCLUSION: The amplicon size analysis proved to be the most accurate method using the haplotype as a possible genetic marker for future testing. Although the results were not significant, further molecular analyses of the DBH gene and other candidate genes can clarify the utility of the molecular phase in psychiatric genetics and personalized medicine. Language: en
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- 2014
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27. DISCREPANCY BETWEEN FIRST IMPRESSION AND SOCIAL DESCRIPTION, AND ITS EFFECT ON PEOPLE’S ATTITUDE
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Tiffany Leung, Hiu Tung, primary and Wincenciak, Joanna, additional
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- 2019
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28. Severe Hypernatremia and Failure to Thrive
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Kevin O’Brien, Christopher Babbitt, and Tiffany Leung
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Male ,medicine.medical_specialty ,Aquaporin 2 ,Hypernatremia ,business.industry ,030232 urology & nephrology ,MEDLINE ,Infant ,Diabetes Insipidus, Nephrogenic ,medicine.disease ,Failure to Thrive ,03 medical and health sciences ,0302 clinical medicine ,030225 pediatrics ,Pediatrics, Perinatology and Child Health ,Failure to thrive ,Diabetes insipidus ,medicine ,Humans ,medicine.symptom ,business ,Intensive care medicine - Published
- 2016
29. An improved method for simple, assumption-free ordinal analysis of the modified Rankin Scale using generalized odds ratios
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Stuart Roberts, Stephen M. Davis, Sarah Arnup, Leonid Churilov, Tiffany Leung, Bruce C.V. Campbell, Geoffrey A. Donnan, and Hayden Johns
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Male ,business.industry ,Nonparametric statistics ,Ordinal analysis ,Odds ratio ,Confidence interval ,Statistics, Nonparametric ,Odds ,Stroke ,Permutation ,Treatment Outcome ,Neurology ,Meta-Analysis as Topic ,Modified Rankin Scale ,Sample size determination ,Data Interpretation, Statistical ,Statistics ,Outcome Assessment, Health Care ,Odds Ratio ,Medicine ,Humans ,Female ,business - Abstract
Background and Purpose : Developing improved methods for analysis of the modified Rankin Scale (mRS) remains a critical issue for the stroke research community. A recently proposed permutation-based approach is assumption-free and easily interpretable but computationally intensive and does not provide confidence intervals to quantify the precision of the effect size estimate. We aimed to develop a method to overcome these limitations. Methods : We propose a procedure using generalized odds ratios to estimate the odds that a patient who received the investigational treatment will have a better outcome than a patient receiving standard treatment. This approach was validated against the permutation method using hypothetical clinical trial scenarios of neuroprotective effect, early recanalization effect, late recanalization effect, and random benefit. Results : The generalized odds ratio approach had strong agreement with the permutation approach provided sample size was >15 patients per treatment arm. Simulation established that the confidence intervals generated were accurate. Ignoring patient pairs with tied mRS scores overestimates the treatment effect compared with splitting tied mRS scores. Conclusions : In addition to all the advantages of the recently proposed permutation-based approach, our method generates confidence intervals without the need for intensive computational power. The resulting generalized odds ratios are particularly suitable for inclusion in meta-analyses and have a simple and intuitive connection with the number-needed-to-treat measure.
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- 2014
30. Robotic Surgery: Applications
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Dinesh Vyas and Tiffany Leung
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Information retrieval ,Text mining ,business.industry ,General Earth and Planetary Sciences ,Medicine ,Robotic surgery ,business ,Data science ,Article ,General Environmental Science - Published
- 2014
31. Applications of nanomedicine in breast cancer detection, imaging, and therapy
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Arpita Vyas, Dinesh Vyas, Lakshmi S. Chaturvedi, Yamaan Saadeh, Tiffany Leung, and Omathanu Perumal
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Oncology ,medicine.medical_specialty ,Materials science ,medicine.medical_treatment ,Biomedical Engineering ,Bioengineering ,Nanotechnology ,Antineoplastic Agents ,Breast Neoplasms ,Breast cancer chemotherapy ,Breast cancer ,Nanocapsules ,Internal medicine ,medicine ,Humans ,General Materials Science ,Molecular Targeted Therapy ,Cancer ,General Chemistry ,Condensed Matter Physics ,medicine.disease ,Review article ,Molecular Imaging ,Nanomedicine ,Drug delivery ,Cancer cell ,Female ,Molecular imaging - Abstract
Worldwide, breast cancer remains as one of the most common cancer diagnosis and cause of cancer related death among women. Fortunately, nanomedicine has brought forth new potential and hope in breast cancer research. The extremely small size of nanoparticles makes it advantageous and potentially superior to use in tumor detection and imaging. One of the more extensively studied particles is quantum dots, semiconductor crystals which are capable of enhanced labeling and imaging of cancer cells. In addition, due to serious toxicity of chemotherapeutic agents, nano-formulations of breast cancer chemotherapy are under investigation and development. This may provide easier administering route and reduced frequency of drugs. With the use of nanoparticles, drug delivery can be carried out in a minimally invasive fashion and treatment regimens can be made much more targeted and specific for each patient. In this review article, we provide an overview on the role nanomedicine has played in breast cancer and mention some of the latest diagnostic and treatment modalities researched to date.
- Published
- 2014
32. LOW-DOSE RECOMBINANT VACCINE ANTIGEN DELIVERY BY ENGINEERED OUTER MEMBRANE VESICLES
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Tiffany Leung, Joseph A. Rosenthal, David Putnam, and Matthew P. DeLisa
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Protein subunit ,Vesicle ,Immunogenicity ,Biology ,medicine.disease_cause ,Virology ,law.invention ,Immune system ,Antigen ,law ,medicine ,Recombinant DNA ,Bacterial outer membrane ,Escherichia coli - Abstract
The use of engineered antigen carriers to optimize the immune response to recombinant subunit vaccines has seen great advances in recent years. Optimization can take several forms, such as facilitating stimulation of certain immune cells or amplifying the adjuvancy effect of the vaccine formulation. In this paper, we applied dose/response analysis to demonstrate the ability of outer membrane vesicle (OMV) antigen carriers derived from engineered Escherichia coli to produce strong antigen-specific immune responses to a model antigen at a significantly decreased antigen load compared to an industry standard alum-based control. Inflammopathology and histological analysis of extended studies further supported a capacity to enhance immune cell recruitment locally at the injection site while decreasing inflammation and eliminating injection site scaring. The results indicate a strong potential for OMV-based vaccines as recombinant antigen delivery vehicles, affording strong immunogenicity at low doses with a broadly applicable platform for recombinant subunit antigen inclusion.
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- 2013
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33. Use of performance data to drive process change and improve patient wait time for chemotherapy treatment
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Maureen E. Trudeau, Flay Charbonneau, Carlo DeAngelis, Tiffany Leung, and Ben De Mendonca
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Cancer Research ,Quality management ,business.industry ,Reservation ,Pharmacy ,Wait time ,Scheduling (computing) ,Value stream mapping ,Workflow ,Oncology ,Medicine ,Operations management ,Performance indicator ,business - Abstract
223 Background: The Odette Cancer Centre (OCC) manages more than 24,000 chemotherapy visits annually. The delivery process is complex and patients have significant wait times for treatment. The OCC was faced with improving this process with no data infrastructure to support continuous quality improvement. Methods: An electronic scheduling manager, Chemotherapy Appointment Reservation Manager (CHARM) was designed that includes workflow communication between pharmacy and nursing. A multidisciplinary team created a value stream map of the process. Rate limiting steps and key milestones in the delivery process were identified. CHARM timestamps stages in the chemotherapy process, from nurse approval to pharmacy verification, medication processing and medications received on the chemotherapy unit. Extracted data was used to create a weekly report to monitor key performance indicators (KPIs). Results: An analysis of six months of data led to the establishment of KPIs and targets. Our baseline targets were established as pharmacy turnaround time (AR) < 1 hour, pharmacy verification (HP)< 13 minutes, medication processing (PR)
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- 2012
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