60 results on '"Leblanc MA"'
Search Results
2. Surveillance for Lyme disease in Canada: 2009–2015
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Gasmi, S, Ogden, NH, Lindsay, LR, Burns, S, Fleming, S, Badcock, J, Hanan, S, Gaulin, C, Leblanc, MA, Russell, C, Nelder, M, Hobbs, L, Graham-Derham, S, Lachance, L, Scott, AN, Galanis, E, and Koffi, JK
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03 medical and health sciences ,Surveillance ,030505 public health ,0302 clinical medicine ,030212 general & internal medicine ,General Medicine ,0305 other medical science - Abstract
To summarize seven years of surveillance data for Lyme disease cases reported in Canada from 2009 to 2015.We describe the incidence over time, seasonal and geographic distribution, demographic and clinical characteristics of reported Lyme disease cases. Logistic regression was used to explore differences between age groups, sex and year to better understand potential demographic risk factors for the occurrence of Lyme disease.The number of reported Lyme disease cases increased more than six-fold, from 144 in 2009 to 917 in 2015, mainly due to an increase in infections acquired in Canada. Most locally acquired cases were reported between May and November. An increase in incidence of Lyme disease was observed in provinces from Manitoba eastwards. This is consistent with our knowledge of range expansion of the tick vectors in this region. In the western provinces the incidence has remained low and stable. All cases reported by Alberta, Saskatchewan and Newfoundland and Labrador were acquired outside of the province, either elsewhere in Canada or abroad. There was a bimodal distribution for Lyme disease by age with peaks at 5-9 and 45-74 years of age. The most common presenting symptom was a single erythema migrans rash (74.2%) and arthritis (35.7%). Variations in the frequency of reported clinical manifestations were observed among age groups and years of study.Lyme disease incidence continues to increase in Canada as does the geographic range of ticks that carry the Lyme disease bacteria. Ongoing surveillance, preventive strategies as well as early disease recognition and treatment will continue to minimize the impact of Lyme disease in Canada.
- Published
- 2017
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3. Surveillance de la maladie de Lyme au Canada, de 2009 à 2015
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Gasmi, S, primary, Ogden, NH, additional, Lindsay, LR, additional, Burns, S, additional, Fleming, S, additional, Badcock, J, additional, Hanan, S, additional, Gaulin, C, additional, Leblanc, MA, additional, Russell, C, additional, Nelder, M, additional, Hobbs, L, additional, Graham Derham, S, additional, Lachance, L, additional, Scott, AN, additional, Galanis, E, additional, and Koffi, JK, additional
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- 2017
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4. A quantitative comparison of four experimental axillary crutches.
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LeBlanc MA, Carlson LE, and Nauenberg T
- Published
- 1993
5. DHAid™ – The vegetarian source
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Freitas Ulla and Leblanc Marie
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docosahexaenoic acid ,DHA ,microalgal oil ,omega-3 ,polyunsaturated fatty acids ,Oils, fats, and waxes ,TP670-699 - Abstract
In humans, DHA occurs naturally as a cell membrane fatty acid in the brain, retina, testes and sperm, and has been reported to be essential in the development of these organs and cells. There it is crucial for the functioning of embedded proteins, i.e. rhodopsin for vision and postsynaptic receptors for neurotransmission. In phospholipids in general, DHA contributes to membrane properties such as fluidity, flexibility and permeability. A deficiency in DHA can lead to memory loss, learning disabilities and impaired visual acuity. Limited storage of DHA in adipose tissue suggests that a continuous supply is needed. These facts clearly demonstrate the physiological importance of DHA for humans and have resulted, for example, in the recommendation of increasing dietary intake of DHA during pregnancy and lactation. Also in the maintenance of cardiovascular health, DHA plays an important role. DHAid™ is a pure vegetarian source of omega-3 docosahexaenoic acid (DHA). It is produced from microalgae in a controlled process in fermentation vessels by the Swiss life-science company Lonza. Due to its renewable sources, DHAid™ is environmentally friendly. DHAid™ is allergen free and is free of potential contaminants that are discussed for seafood.
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- 2008
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6. Memorial/tribute: a tribute to John Lyman, PhD.
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LeBlanc MA
- Published
- 2001
7. Prevention of catheter lumen occlusion with rT-PA versus heparin (Pre-CLOT): study protocol of a randomized trial [ISRCTN35253449]
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Berall Murray J, Tam Paul YW, Dorval Marc, Lok Charmaine, Pilkey Rachel M, Moist Louise, Hemmelgarn Brenda R, LeBlanc Martine, Toffelmire Edwin B, Manns Braden J, and Scott-Douglas Nairne
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Diseases of the genitourinary system. Urology ,RC870-923 - Abstract
Abstract Background Many patients with end-stage renal disease use a central venous catheter for hemodialysis access. A large majority of these catheters malfunction within one year of insertion, with up to two-thirds due to thrombosis. The optimal solution for locking the catheter between hemodialysis sessions, to decrease the risk of thrombosis and catheter malfunction, is unknown. The Prevention of Catheter Lumen Occlusion with rt-PA versus Heparin (PreCLOT) study will determine if use of weekly rt-PA, compared to regular heparin, as a catheter locking solution, will decrease the risk of catheter malfunction. Methods/Design The study population will consist of patients requiring chronic hemodialysis thrice weekly who are dialyzed with a newly inserted permanent dual-lumen central venous catheter. Patients randomized to the treatment arm will receive rt-PA 1 mg per lumen once per week, with heparin 5,000 units per ml as a catheter locking solution for the remaining two sessions. Patients randomized to the control arm will receive heparin 5,000 units per ml as a catheter locking solution after each dialysis session. The study treatment period will be six months, with 340 patients to be recruited from 14 sites across Canada. The primary outcome will be catheter malfunction, based on mean blood flow parameters while on hemodialysis, with a secondary outcome of catheter-related bacteremia. A cost-effectiveness analysis will be undertaken to assess the cost of maintaining a catheter using rt-PA as a locking solution, compared to the use of heparin. Discussion Results from this study will determine if use of weekly rt-PA, compared to heparin, will decrease catheter malfunction, as well as assess the cost-effectiveness of these locking solutions.
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- 2006
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8. Risk factors for acute appendicitis among adult patients with indeterminate ultrasound.
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Doubova M, Cortel-LeBlanc MA, Mckinnon M, Osman H, Nemnom MJ, Macdonald B, and Thiruganasambandamoorthy V
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Objectives: Abdominal ultrasound is used for diagnosing appendicitis in patients with right lower quadrant abdominal pain. Between 45 and 82% of radiology performed ultrasounds are indeterminate for appendicitis and computed tomography is required for diagnostic confirmation. Our study aims to determine predictors to rule out appendicitis when ultrasound is indeterminate., Methods: We performed a health records review of adult emergency department (ED) patients presenting with symptoms suspicious for appendicitis and indeterminate ultrasound to two academic EDs between June 2019 and July 2020. The outcome was appendicitis diagnosis within 30 days of the index ED visit. We used multivariable logistic regression, identifying a cut-off threshold for continuous variables with cubic spline, and chose the parsimonious model to develop a binary decision rule. We report Odds ratios (OR) and diagnostic performance with 95% confidence intervals (CI)., Results: Overall, 463 patients (mean age 30.3 years (SD 10.5 years), 74.9% female) were included. Appendicitis was diagnosed in 45 patients (9.7% [95% CI 7.2-12.8%]). After ultrasound, computed tomography was performed in 227 patients (49.0%) and 39 patients (17.2%) were diagnosed with appendicitis. Among the 236 patients who did not have a subsequent computed tomography, 6 (2.6%) patients had appendicitis. Neutrophil count > 5.5 × 10
9 /L (OR 1.21 [95% CI 1.12-1.30]) and secondary signs of inflammation on ultrasound (OR 2.16 [1.07-4.37]) were associated with a higher likelihood of appendicitis (C-statistic 0.77 [95% CI 0.70-0.84]). The absence of both predictors had a sensitivity of 88.9% (95% CI 76.0-96.3%), specificity of 45.7% (95% CI 40.8-50.6%) and a negative predictive value of 0.97 (95% CI 0.94-0.99) to rule out appendicitis., Conclusion: For patients suspected of appendicitis and indeterminate ultrasound, the absence of an elevated neutrophil count and secondary signs of inflammation are associated with a low probability of appendicitis., (© 2024. The Author(s), under exclusive licence to the Canadian Association of Emergency Physicians (CAEP)/ Association Canadienne de Médecine d'Urgence (ACMU).)- Published
- 2024
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9. The 2023 protocol for update to acute treatment of adults with migraine in the emergency department: The American Headache Society evidence assessment of parenteral pharmacotherapies.
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Robblee J, Zhao XR, Minen MT, Friedman BW, Cortel-LeBlanc MA, Cortel-LeBlanc A, and Orr SL
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- Humans, Systematic Reviews as Topic, Adult, Societies, Medical standards, Practice Guidelines as Topic standards, Meta-Analysis as Topic, Migraine Disorders drug therapy, Emergency Service, Hospital standards
- Abstract
Objectives: The primary objective of this proposed guideline is to update the prior 2016 guideline on parenteral pharmacotherapies for the management of adults with a migraine attack in the emergency department (ED)., Methods: We will conduct an updated systematic review and meta-analysis using the 2016 guideline methodology to provide clinical recommendations. The same search strategy will be used for studies up to 2023, with a new search strategy added to capture studies of nerve blocks and sphenopalatine blocks. Medline, Embase, Cochrane, clinicaltrials.gov, and the World Health Organization International Clinical Trial Registry Platform will be searched. Our inclusion criteria consist of studies involving adults with a diagnosis of migraine, utilizing medications administered intravenously, intramuscularly, or subcutaneously in a randomized controlled trial design. Two authors will perform the selection of studies based on title and abstract, followed by a full-text review. A third author will intervene in cases of disagreements. Data will be recorded in a standardized worksheet and subjected to verification. The risk of bias will be assessed using the American Academy of Neurology tool. When applicable, a meta-analysis will be conducted. The efficacy of medications will be evaluated, categorizing them as "highly likely," "likely", or "possibly effective" or "ineffective." Subsequently, clinical recommendations will be developed, considering the risk associated with the medications, following the American Academy of Neurology recommendation development process., Results: The goal of this updated guideline will be to provide guidance on which injectable medications, including interventional approaches (i.e., nerve blocks, sphenopalatine ganglion), should be considered effective acute treatment for adults with migraine who present to an ED., Conclusions: The methods outlined in this protocol will be used in the design of a future systematic review and meta-analysis-informed guideline, which will then be assessed by and submitted for endorsement by the American Headache Society., (© 2024 American Headache Society.)
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- 2024
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10. Peripheral nervous system and neuromuscular disorders in the emergency department: A review.
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Sivadasan A, Cortel-LeBlanc MA, Cortel-LeBlanc A, and Katzberg H
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- Humans, Emergencies, Emergency Service, Hospital, Peripheral Nervous System, Meta-Analysis as Topic, Systematic Reviews as Topic, Guillain-Barre Syndrome diagnosis, Guillain-Barre Syndrome therapy, Myasthenia Gravis diagnosis, Myasthenia Gravis therapy, Neuromuscular Diseases diagnosis, Neuromuscular Diseases therapy
- Abstract
Introduction: Acute presentations and emergencies in neuromuscular disorders (NMDs) often challenge clinical acumen. The objective of this review is to refine the reader's approach to history taking, clinical localization and early diagnosis, as well as emergency management of neuromuscular emergencies., Methods: An extensive literature search was performed to identify relevant studies. We prioritized meta-analysis, systematic reviews, and position statements where possible to inform any recommendations., Summary: The spectrum of clinical presentations and etiologies ranges from neurotoxic envenomation or infection to autoimmune disease such as Guillain-Barré Syndrome (GBS) and myasthenia gravis (MG). Delayed diagnosis is not uncommon when presentations occur "de novo," respiratory failure is dominant or isolated, or in the case of atypical scenarios such as GBS variants, severe autonomic dysfunction, or rhabdomyolysis. Diseases of the central nervous system, systemic and musculoskeletal disorders can mimic presentations in neuromuscular disorders., Conclusions: Fortunately, early diagnosis and management can improve prognosis. This article provides a comprehensive review of acute presentations in neuromuscular disorders relevant for the emergency physician., (© 2024 The Authors. Academic Emergency Medicine published by Wiley Periodicals LLC on behalf of Society for Academic Emergency Medicine.)
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- 2024
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11. A case report of an atypical severe case of skin picking disorder managed by a multidisciplinary team.
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LeBlanc MA, Hudec MA, and Weise L
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- Male, Humans, Adult, Excoriation Disorder, Comorbidity, Treatment Outcome, Patient Care Team, Antipsychotic Agents, Self-Injurious Behavior diagnosis, Self-Injurious Behavior therapy, Self-Injurious Behavior complications
- Abstract
Background: While skin picking disorder remains relatively common, it often does not present to psychiatry until significant morbidity or comorbidities are reached. It is described as recurrent picking of skin leading to skin lesions, with repeated attempts to decrease or stop skin picking. It is also often associated with significant distress or functional impairment. There has been limited research in this specific disorder and treatment efficacy has often been poor in severe cases. For various reasons, only a small amount of patients with this disorder present to care, and often to a multidisciplinary team prior to psychiatry., Case Presentation: This is a case presentation of a 44 year old male with a complex past psychiatric history, ultimately untreated for an underlying skin picking disorder. He presented for urgent medical care following a self-inflicted wound through the central frontal bone and dura over the course of 2 years. He was treated with current psychiatric evidence based medicine, including an SSRI, antipsychotic augmentation and NAC, along with habit reversal techniques during the admission. He was concurrently managed with the neurosurgery team, initially with a poor prognosis due to the severity of his presentation. He required debriding of the devitalized bone within the adjacent brain to cover the dural defect, IV antibiotics for 6 weeks, and an initial skin graft on his initial admission., Conclusions: This case in particular highlighted the importance of urgent treatment via a multidisciplinary approach to avoid mortality. It highlights the importance of increasing awareness about the disorder and that treatment with SSRI's, along with antipsychotic and NAC adjuncts remains the mainstay of acute treatment., (© 2024. The Author(s).)
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- 2024
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12. Atypical Neuropsychiatric Presentation of FTD-ALS Caused by a Pathogenic Repeat Expansion in C9orf72 : A Case Report.
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LeBlanc MA, Gough A, Rideout AL, Dyack S, Singh K, and MacNeil M
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- Humans, Male, C9orf72 Protein genetics, DNA Repeat Expansion, Mutation, Adult, Amyotrophic Lateral Sclerosis diagnosis, Amyotrophic Lateral Sclerosis genetics, Frontotemporal Dementia diagnosis, Frontotemporal Dementia genetics
- Abstract
The case report describes the presentation of a 42-year-old male ultimately diagnosed with FTD-ALS caused by a genetic mutation, who initially presented with atypical psychiatric symptoms. Given that the initial clinical manifestations of FTD-ALS can be quite variable, the diagnosis is often challenging; the case report aims to highlight several key considerations in the diagnostic assessment, including genetic testing in order to guide clinicians in more timely diagnosis and ultimately improve patient care., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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- 2024
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13. Managing and Preventing Migraine in the Emergency Department: A Review.
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Cortel-LeBlanc MA, Orr SL, Dunn M, James D, and Cortel-LeBlanc A
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- Humans, Emergency Service, Hospital, Seizures, Migraine Disorders prevention & control, Epilepsy complications
- Abstract
Migraine is a leading cause of disability worldwide, and acute migraine attacks are a common reason for patients to seek care in the emergency department (ED). There have been recent advancements in the care of patients with migraine, specifically emerging evidence for nerve blocks and new pharmacological classes of medications like gepants and ditans. This article serves as a comprehensive review of migraine in the ED, including diagnosis and management of acute complications of migraine (eg, status migrainosus, migrainous infarct, persistent aura without infarction, and aura-triggered seizure) and use of evidence-based migraine-specific treatments in the ED. It highlights the role of migraine preventive medications and provides a framework for emergency physicians to prescribe them to eligible patients. Finally, it evaluates the evidence for nerve blocks in the treatment of migraine and introduces the possible role of gepants and ditans in the care of patients with migraine in the ED., (Copyright © 2023 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
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14. Risk of sexual transmission of HIV in the context of viral load suppression.
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Djiadeu P, Begum H, Sabourin S, Gadient S, Archibald C, LeBlanc MA, Chittle A, Fleurant A, and Cox J
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Background: In 2018, the Public Health Agency of Canada (PHAC) published a systematic review to calculate the risk of sexual transmission of human immunodeficiency virus (HIV) in the context of antiretroviral therapy (ART). In 2022, PHAC commissioned the Canadian Agency for Drugs and Technologies in Health (CADTH) to conduct a rapid review of evidence published since 2017. We undertook a meta-analysis of relevant studies from these two reviews., Methods: Studies from the rapid review that adequately assessed exposure (HIV viral load) and outcome (HIV seroconversion) were included and assessed for risk of bias (RoB) and certainty of evidence. Results were pooled to estimate the risk of HIV transmission per 100 person-years., Results: Three studies from the rapid review were eligible for inclusion and one was excluded after RoB assessment. In the remaining studies examining risk among people living with HIV who take ART and maintain a suppressed viral load (fewer than 200 copies/mL, measured every 4-6 months), no sexual transmissions of HIV were observed. The pooled incidence estimate based on these studies, and one from the 2018 PHAC review, was zero transmissions/100 person-years (95% CI: 0.00-0.10). No studies in the rapid review provided data on the risk of sexual transmission of HIV in situations of varying levels of viral load., Conclusion: This update highlights the consistency of evidence since the 2018 PHAC review. There remains no evidence of HIV transmission to sexual partners when a person living with HIV is on ART and maintains a suppressed viral load.
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- 2023
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15. Medico-legal risk and use of medical directives in the emergency department.
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Cortel-LeBlanc MA, Lemay K, Woods S, Bakewell F, Liu R, and Garber G
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- Humans, Canada, Triage, Hospitals, Emergency Service, Hospital, Physicians
- Abstract
Purpose: The medico-legal risk associated with application of medical directives in the emergency department (ED) is unknown. The objective of this study was to describe and analyze factors associated with medico-legal risk in cases involving medical directives in the ED., Methods: We conducted a descriptive analysis of closed medico-legal cases [hospital complaints, regulatory authority (i.e., College) complaints, and civil legal actions] involving emergency physicians in Canadian EDs involving medical directives (alternate terms including "standing order", "nursing initiated", "nurse initiated", "nursing order", "triage initiated", "triage ordered", "directive", "ED protocol", and "ED's protocol"). We used data from closed cases involving the Canadian Medical Protective Association from January 2016 until December 2021. We abstracted descriptive factors of the cases and used a framework for contributing factors classification., Results: From 2016 until 2021, 43,332 cases were closed and 1957 involved emergency physicians for which there was medico-legal information available for analysis. In all, 28 involved emergency physicians and medical directives. Situational awareness, team communication, and issues with clinical decision-making were the most important factors contributing to harm and medico-legal risk. Peer experts were critical of physicians not reviewing all results available for patients when initiated through a directive, misinterpreting test results, a less than thorough initial assessment, and of failing to reassess patients or re-order investigations when indicated., Conclusion: Our findings suggest that the medico-legal risk exposure from the use of medical directives in the ED is low. Emergency departments may consider implementing systems to support adherence to medical directive policies, ensure physicians are alerted when medical directives are completed in a timely fashion, and leverage tools to notify the healthcare team when results have not been reviewed., (© 2023. The Author(s), under exclusive licence to Canadian Association of Emergency Physicians (CAEP)/ Association Canadienne de Médecine d'Urgence (ACMU).)
- Published
- 2023
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16. Definitions and factors associated with emergency physician productivity: a scoping review.
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Anjum O, Yadav K, Chhabra S, Mallick R, Fournier K, Thiruganasambandamoorthy V, and Cortel-LeBlanc MA
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- Humans, Efficiency, Hospitalization, Electronic Health Records, Emergency Service, Hospital, Efficiency, Organizational, Physicians
- Abstract
Purpose: There currently exists no standard productivity measure for emergency physicians. The objectives of this scoping review were to synthesize the literature to identify components of definitions and measurements of emergency physician productivity and to evaluate factors associated with productivity., Methods: We searched Medline, Embase, CINAHL, and ProQuest One Business from inception to May 2022. We included all studies that reported on emergency physician productivity. We excluded studies that only reported departmental productivity, studies with non-emergency providers, review articles, case reports, and editorials. Data were extracted into predefined worksheets and a descriptive summary was presented. Quality analysis was performed with Newcastle-Ottawa Scale., Results: After screening 5521 studies, 44 studies met full inclusion criteria. Components of the definition for emergency physician productivity included: number of patients managed, revenue generated, patient processing time, and a standardization factor. Most studies measured productivity using patients per hour, relative value units per hour, and provider-to-disposition time. The most studied factors influencing productivity included scribes, resident learners, electronic medical record implementation, and faculty teaching scores., Conclusion: Emergency physician productivity is heterogeneously defined, but includes common elements such as patient volume, complexity, and processing time. Commonly reported productivity metrics include patients per hour and relative value units that incorporate patient volume and complexity, respectively. The findings of this scoping review can guide ED physicians and administrators to measure the impact of QI initiatives, promote efficient patient care, and optimize physician staffing., (© 2023. The Author(s), under exclusive licence to Canadian Association of Emergency Physicians (CAEP)/ Association Canadienne de Médecine d'Urgence (ACMU).)
- Published
- 2023
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17. Wired Sex Assemblages Among Men Who Have Sex with Men: Sexualized Drug Use, Hookup Apps, and HIV Service Provision.
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Holmes D, Numer M, Hammond C, Joy P, Sinno J, Patten S, and Leblanc MA
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- Male, Humans, Homosexuality, Male, Sexual Behavior, Bisexuality, Sexual and Gender Minorities, HIV Infections epidemiology, Substance-Related Disorders epidemiology, Substance-Related Disorders therapy
- Abstract
Sexualized drug use is a form of sexual practice that resists risk-based discourses (otherwise referred to as "radical sex practices") and is reportedly common among gay, bisexual and other men who have sex with men (GBMSM). With the growth of online technologies, the use of hookup apps has also increased. We refer to men's use of drugs, apps, and sex form as "wired sex" that forms what post-structuralist theorists Deleuze and Guattari described as an assemblage . Perspectives of the health and social service providers who work directly with GBMSM has not been explored. This research project involved a critical discourse analysis of 13 semi-structured interviews with service providers in Canada to understand their perspectives and interactions with wired sex assemblages. We identified several themes reflecting the social and political effects of wired sex assemblages and discuss the implications of these effects on services provision with GBMSM.
- Published
- 2023
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18. Predictors of neurologists confirming or overturning emergency physicians' diagnosis of TIA or stroke.
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Cortel-LeBlanc MA, Sharma M, Cortel-LeBlanc A, Sivilotti MLA, Émond M, Stiell IG, Stotts G, Lee J, Worster A, Morris J, Cheung KW, Jin AY, Oczkowski WJ, Sahlas DJ, Murray HE, Mackey A, Verreault S, Camden MC, Yip S, Teal P, Gladstone DJ, Boulos MI, Chagnon N, Shouldice E, Atzema C, Slaoui T, Teitelbaum J, Abdulaziz KE, Wells GA, Taljaard M, and Perry JJ
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- Canada epidemiology, Emergency Service, Hospital, Humans, Neurologists, Prospective Studies, Risk Factors, Ischemic Attack, Transient diagnosis, Ischemic Attack, Transient epidemiology, Physicians
- Abstract
Background: Transient ischemic attack (TIA) and non-disabling stroke are common emergency department (ED) presentations. Currently, there are no prospective multicenter studies determining predictors of neurologists confirming a diagnosis of cerebral ischemia in patients discharged with a diagnosis of TIA or stroke. The objectives were to (1) calculate the concordance between emergency physicians and neurologists for the outcome of diagnosing TIA or stroke, and (2) identify characteristics associated with neurologists diagnosing a stroke mimic., Methods: This was a planned sub-study of a prospective cohort study at 14 Canadian EDs enrolling patients diagnosed with TIA or non-disabling stroke from 2006 to 2017. Logistic regression was used to identify factors associated with neurologists' diagnosis of cerebral ischemia. Our primary outcome was the composite outcome of cerebral ischemia (TIA or non-disabling stroke) based on the neurologists' assessment., Results: The diagnosis of cerebral ischemia was confirmed by neurologists in 5794 patients (55.4%). The most common identified stroke mimics were migraine (18%), peripheral vertigo (7%), syncope (4%), and seizure (3%). Over a third of patients (38.4%) ultimately had an undetermined aetiology for their symptoms. The strongest predictors of cerebral ischemia confirmation were infarct on CT (OR 1.83, 95% CI 1.65-2.02), advanced age (OR comparing 75th-25th percentiles 1.67, 1.55-1.80), language disturbance (OR 1.92, 1.75-2.10), and smoking (OR 1.67, 1.46-1.91). The strongest predictors of stroke mimics were syncope (OR 0.59, 0.48-0.72), vertigo (OR 0.52, 0.45-0.59), bilateral symptoms (OR 0.60, 0.50-0.72), and confusion (OR 0.50, 0.44-0.57)., Conclusion: Physicians should have a high index of suspicion of cerebral ischemia in patients with advanced age, smoking history, language disturbance, or infarcts on CT. Physicians should discriminate in which patients to pursue stroke investigations on when deemed at minimal risk of cerebral ischemia, including those with isolated vertigo, syncope, or bilateral symptoms., (© 2021. The Author(s), under exclusive licence to Canadian Association of Emergency Physicians (CAEP)/ Association Canadienne de Médecine d'Urgence (ACMU).)
- Published
- 2021
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19. Genetic counselling for the prevention of mental health consequences of cannabis use: A randomized controlled trial-within-cohort.
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Zwicker A, LeBlanc MA, Pavlova B, Alda M, Denovan-Wright EM, Uher R, and Austin JC
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- Adolescent, Child, Cohort Studies, Genetic Counseling, Humans, Mental Health, Cannabis, Psychotic Disorders genetics, Psychotic Disorders prevention & control
- Abstract
Background: Cannabis use is a risk factor for severe mental illness. However, cannabis does not affect everyone equally. Genetic information may help identify individuals who are more vulnerable to the harmful effects of cannabis on mental health. A common genetic variant within the AKT1 gene selectively increases risk of psychosis, only among those who use cannabis. Therapeutically oriented genetic counselling may enable us to reduce cannabis exposure among genetically sensitive individuals., Methods: Using a trial-within-cohort design, we aim to test if genetic counselling, including the option to receive AKT1 rs2494732 genotype, reduces cannabis use. To this end, we have designed a genetic counselling intervention: Interdisciplinary approach to Maximize Adolescent potential: Genetic counselling Intervention to reduce Negative Environmental effects (IMAGINE)., Results: IMAGINE will be implemented in a cohort of children and youth enriched for familial risk for major mood and psychotic disorders. Approximately 110 eligible individuals aged 12-21 years will be randomized in a 1:1 ratio to be offered a single genetic counselling session with a board-certified genetic counsellor, or not. Allocated youth will also be invited to attend a follow-up session approximately 1 month following the intervention. The primary outcome will be cannabis use (measured by self-report or urine screen) at subsequent annual assessments as part of the larger cohort study. Secondary outcomes include intervention acceptability and psychopathology., Conclusion: This study represents the first translational application of a gene-environment interaction to improve mental health and test an intervention with potential public health benefits. This study is registered with clinicaltrials.gov (NCT03601026)., (© 2020 John Wiley & Sons Australia, Ltd.)
- Published
- 2021
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20. Functional neurological disorder in the emergency department.
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Finkelstein SA, Cortel-LeBlanc MA, Cortel-LeBlanc A, and Stone J
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- Emergency Service, Hospital, Humans, Seizures, Conversion Disorder diagnosis, Conversion Disorder therapy
- Abstract
We provide a narrative review of functional neurological disorder (FND, or conversion disorder) for the emergency department (ED). Diagnosis of FND has shifted from a "rule-out" disorder to one now based on the recognition of positive clinical signs, allowing the ED physician to make a suspected or likely diagnosis of FND. PubMed, Google Scholar, academic books, and a hand search through review article references were used to conduct a literature review. We review clinical features and diagnostic pitfalls for the most common functional neurologic presentations to the ED, including functional limb weakness, functional (nonepileptic) seizures, and functional movement disorders. We provide practical advice for discussing FND as a possible diagnosis and suggestions for initial steps in workup and management plans., (© 2021 The Authors. Academic Emergency Medicine published by Wiley Periodicals LLC on behalf of Society for Academic Emergency Medicine.)
- Published
- 2021
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21. Type III secretion system effector proteins are mechanically labile.
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LeBlanc MA, Fink MR, Perkins TT, and Sousa MC
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- Bacterial Proteins chemistry, Gram-Negative Bacteria physiology, Gram-Negative Bacteria ultrastructure, Microscopy, Atomic Force, Protein Stability, Salmonella physiology, Salmonella ultrastructure, Thermodynamics, Bacterial Physiological Phenomena, Bacterial Proteins metabolism, Type III Secretion Systems metabolism
- Abstract
Multiple gram-negative bacteria encode type III secretion systems (T3SS) that allow them to inject effector proteins directly into host cells to facilitate colonization. To be secreted, effector proteins must be at least partially unfolded to pass through the narrow needle-like channel (diameter <2 nm) of the T3SS. Fusion of effector proteins to tightly packed proteins-such as GFP, ubiquitin, or dihydrofolate reductase (DHFR)-impairs secretion and results in obstruction of the T3SS. Prior observation that unfolding can become rate-limiting for secretion has led to the model that T3SS effector proteins have low thermodynamic stability, facilitating their secretion. Here, we first show that the unfolding free energy ([Formula: see text]) of two Salmonella effector proteins, SptP and SopE2, are 6.9 and 6.0 kcal/mol, respectively, typical for globular proteins and similar to published [Formula: see text] for GFP, ubiquitin, and DHFR. Next, we mechanically unfolded individual SptP and SopE2 molecules by atomic force microscopy (AFM)-based force spectroscopy. SptP and SopE2 unfolded at low force ( F
unfold ≤ 17 pN at 100 nm/s), making them among the most mechanically labile proteins studied to date by AFM. Moreover, their mechanical compliance is large, as measured by the distance to the transition state (Δ x‡ = 1.6 and 1.5 nm for SptP and SopE2, respectively). In contrast, prior measurements of GFP, ubiquitin, and DHFR show them to be mechanically robust ( Funfold > 80 pN) and brittle (Δ x‡ < 0.4 nm). These results suggest that effector protein unfolding by T3SS is a mechanical process and that mechanical lability facilitates efficient effector protein secretion., Competing Interests: The authors declare no competing interest.- Published
- 2021
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22. Modulation of a protein-folding landscape revealed by AFM-based force spectroscopy notwithstanding instrumental limitations.
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Edwards DT, LeBlanc MA, and Perkins TT
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- Hydrogen-Ion Concentration, Mechanical Phenomena, Microscopy, Atomic Force instrumentation, Single Molecule Imaging, Microscopy, Atomic Force methods, Models, Molecular, Protein Folding, Proteins chemistry
- Abstract
Single-molecule force spectroscopy is a powerful tool for studying protein folding. Over the last decade, a key question has emerged: how are changes in intrinsic biomolecular dynamics altered by attachment to μm-scale force probes via flexible linkers? Here, we studied the folding/unfolding of α
3 D using atomic force microscopy (AFM)-based force spectroscopy. α3 D offers an unusual opportunity as a prior single-molecule fluorescence resonance energy transfer (smFRET) study showed α3 D's configurational diffusion constant within the context of Kramers theory varies with pH. The resulting pH dependence provides a test for AFM-based force spectroscopy's ability to track intrinsic changes in protein folding dynamics. Experimentally, however, α3 D is challenging. It unfolds at low force (<15 pN) and exhibits fast-folding kinetics. We therefore used focused ion beam-modified cantilevers that combine exceptional force precision, stability, and temporal resolution to detect state occupancies as brief as 1 ms. Notably, equilibrium and nonequilibrium force spectroscopy data recapitulated the pH dependence measured using smFRET, despite differences in destabilization mechanism. We reconstructed a one-dimensional free-energy landscape from dynamic data via an inverse Weierstrass transform. At both neutral and low pH, the resulting constant-force landscapes showed minimal differences (∼0.2 to 0.5 kB T ) in transition state height. These landscapes were essentially equal to the predicted entropic barrier and symmetric. In contrast, force-dependent rates showed that the distance to the unfolding transition state increased as pH decreased and thereby contributed to the accelerated kinetics at low pH. More broadly, this precise characterization of a fast-folding, mechanically labile protein enables future AFM-based studies of subtle transitions in mechanoresponsive proteins., Competing Interests: The authors declare no competing interest.- Published
- 2021
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23. Is HIV prevention creating new biosocialities among gay men? Treatment as prevention and pre-exposure prophylaxis in Canada.
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Girard G, Patten S, LeBlanc MA, Adam BD, and Jackson E
- Subjects
- Adult, Canada, Community-Based Participatory Research, Focus Groups, HIV Infections virology, Humans, Male, Middle Aged, Racial Groups, Risk Reduction Behavior, Risk-Taking, Social Responsibility, Viral Load, Anti-Retroviral Agents administration & dosage, Bisexuality psychology, HIV Infections prevention & control, Homosexuality, Male psychology, Pre-Exposure Prophylaxis methods, Sexual and Gender Minorities psychology
- Abstract
The advancements of "treatment as prevention" (TasP), "undetectable viral load" (UVL) and "pre-exposure prophylaxis" (PrEP) are redefining HIV prevention standards. Relying on the concept of biosociality, this article explores how gay men rally around, debate, and sometimes disagree about these emerging HIV prevention technologies. This article is based on data from the Resonance Project, a Canadian community-based research project. Twelve focus groups (totalling 86 gay and bisexual men) were held in three Canadian cities (Montreal, Toronto, Vancouver) in 2013-2014. Respondents view UVL and PrEP through the prism of their generational experience of HIV prevention. In this respect, biosocialities highlight an experiential dimension that is tied to the context of the HIV epidemic. The biosocialities of HIV prevention are also built around serological identities. However, our study shows the diversity of these positions. Analysis grounded in biosocialities is useful for better understanding how scientific information circulates, is made sense of, and generates debate among gay men., (© 2018 Foundation for the Sociology of Health & Illness.)
- Published
- 2019
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24. Force Spectroscopy with 9-μs Resolution and Sub-pN Stability by Tailoring AFM Cantilever Geometry.
- Author
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Edwards DT, Faulk JK, LeBlanc MA, and Perkins TT
- Subjects
- Equipment Design, Gold, Microscopy, Atomic Force instrumentation
- Abstract
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is a powerful yet accessible means to characterize the unfolding/refolding dynamics of individual molecules and resolve closely spaced, transiently occupied folding intermediates. On a modern commercial AFM, these applications and others are now limited by the mechanical properties of the cantilever. Specifically, AFM-based SMFS data quality is degraded by a commercial cantilever's limited combination of temporal resolution, force precision, and force stability. Recently, we modified commercial cantilevers with a focused ion beam to optimize their properties for SMFS. Here, we extend this capability by modifying a 40 × 18 μm
2 cantilever into one terminated with a gold-coated, 4 × 4 μm2 reflective region connected to an uncoated 2-μm-wide central shaft. This "Warhammer" geometry achieved 8.5-μs resolution coupled with improved force precision and sub-pN stability over 100 s when measured on a commercial AFM. We highlighted this cantilever's biological utility by first resolving a calmodulin unfolding intermediate previously undetected by AFM and then measuring the stabilization of calmodulin by myosin light chain kinase at dramatically higher unfolding velocities than in previous AFM studies. More generally, enhancing data quality via an improved combination of time resolution, force precision, and force stability will broadly benefit biological applications of AFM., (Published by Elsevier Inc.)- Published
- 2017
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25. Errata: Functional annotation of chemical libraries across diverse biological processes.
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Piotrowski JS, Li SC, Deshpande R, Simpkins SW, Nelson J, Yashiroda Y, Barber JM, Safizadeh H, Wilson E, Okada H, Gebre AA, Kubo K, Torres NP, LeBlanc MA, Andrusiak K, Okamoto R, Yoshimura M, DeRango-Adem E, van Leeuwen J, Shirahige K, Baryshnikova A, Brown GW, Hirano H, Costanzo M, Andrews B, Ohya Y, Osada H, Yoshida M, Myers CL, and Boone C
- Abstract
This corrects the article DOI: 10.1038/nchembio.2436.
- Published
- 2017
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26. Functional annotation of chemical libraries across diverse biological processes.
- Author
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Piotrowski JS, Li SC, Deshpande R, Simpkins SW, Nelson J, Yashiroda Y, Barber JM, Safizadeh H, Wilson E, Okada H, Gebre AA, Kubo K, Torres NP, LeBlanc MA, Andrusiak K, Okamoto R, Yoshimura M, DeRango-Adem E, van Leeuwen J, Shirahige K, Baryshnikova A, Brown GW, Hirano H, Costanzo M, Andrews B, Ohya Y, Osada H, Yoshida M, Myers CL, and Boone C
- Subjects
- Drug Evaluation, Preclinical, Gene Expression Profiling, Molecular Structure, Drug Delivery Systems, Small Molecule Libraries
- Abstract
Chemical-genetic approaches offer the potential for unbiased functional annotation of chemical libraries. Mutations can alter the response of cells in the presence of a compound, revealing chemical-genetic interactions that can elucidate a compound's mode of action. We developed a highly parallel, unbiased yeast chemical-genetic screening system involving three key components. First, in a drug-sensitive genetic background, we constructed an optimized diagnostic mutant collection that is predictive for all major yeast biological processes. Second, we implemented a multiplexed (768-plex) barcode-sequencing protocol, enabling the assembly of thousands of chemical-genetic profiles. Finally, based on comparison of the chemical-genetic profiles with a compendium of genome-wide genetic interaction profiles, we predicted compound functionality. Applying this high-throughput approach, we screened seven different compound libraries and annotated their functional diversity. We further validated biological process predictions, prioritized a diverse set of compounds, and identified compounds that appear to have dual modes of action.
- Published
- 2017
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27. Rapid Characterization of a Mechanically Labile α-Helical Protein Enabled by Efficient Site-Specific Bioconjugation.
- Author
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Walder R, LeBlanc MA, Van Patten WJ, Edwards DT, Greenberg JA, Adhikari A, Okoniewski SR, Sullan RMA, Rabuka D, Sousa MC, and Perkins TT
- Subjects
- Hydrogen-Ion Concentration, Microscopy, Atomic Force, Protein Conformation, alpha-Helical, Temperature, Proteins chemistry
- Abstract
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is a powerful yet accessible means to characterize mechanical properties of biomolecules. Historically, accessibility relies upon the nonspecific adhesion of biomolecules to a surface and a cantilever and, for proteins, the integration of the target protein into a polyprotein. However, this assay results in a low yield of high-quality data, defined as the complete unfolding of the polyprotein. Additionally, nonspecific surface adhesion hinders studies of α-helical proteins, which unfold at low forces and low extensions. Here, we overcame these limitations by merging two developments: (i) a polyprotein with versatile, genetically encoded short peptide tags functionalized via a mechanically robust Hydrazino-Pictet-Spengler ligation and (ii) the efficient site-specific conjugation of biomolecules to PEG-coated surfaces. Heterobifunctional anchoring of this polyprotein construct and DNA via copper-free click chemistry to PEG-coated substrates and a strong but reversible streptavidin-biotin linkage to PEG-coated AFM tips enhanced data quality and throughput. For example, we achieved a 75-fold increase in the yield of high-quality data and repeatedly probed the same individual polyprotein to deduce its dynamic force spectrum in just 2 h. The broader utility of this polyprotein was demonstrated by measuring three diverse target proteins: an α-helical protein (calmodulin), a protein with internal cysteines (rubredoxin), and a computationally designed three-helix bundle (α
3 D). Indeed, at low loading rates, α3 D represents the most mechanically labile protein yet characterized by AFM. Such efficient SMFS studies on a commercial AFM enable the rapid characterization of macromolecular folding over a broader range of proteins and a wider array of experimental conditions (pH, temperature, denaturants). Further, by integrating these enhancements with optical traps, we demonstrate how efficient bioconjugation to otherwise nonstick surfaces can benefit diverse single-molecule studies.- Published
- 2017
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28. Anatomic Versus Mechanically Aligned Total Knee Arthroplasty for Unicompartmental Knee Arthroplasty Revision.
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Toliopoulos P, LeBlanc MA, Hutt J, Lavigne M, Desmeules F, and Vendittoli PA
- Abstract
Objectives: The purpose of this study was to compare the intra-operative benefits and the clinical outcomes from kinematic or mechanical alignment for total knee arthroplasty (TKA) in patients undergoing revision of failed unicompartmental kneel arthroplasty (UKA) to TKA., Methods: Ten revisions were performed with a kinematic alignment technique and 11 with a mechanical alignment. Measurements of the hip-knee-ankle angle (HKA), the lateral distal femoral angle (LDFA), and the medial proximal tibial angle (MPTA) were performed using long-leg radiographs. The need for augments, stems, and constrained inserts was compared between groups. Clinical outcomes were compared using the WOMAC score along with maximum distance walked as well as knee range of motion obtained prior to discharge. All data was obtained by a retrospective review of patient files., Results: The kinematic group required less augments, stems, and constrained inserts than the mechanical group and thinner polyethylene bearings. There were significant differences in the lateral distal femoral angle (LDFA) and the medial proximal tibial angle (MPTA) between the two groups (p<0.05). The mean WOMAC score obtained at discharge was better in the kinematic group as was mean knee flexion. At last follow up of 34 months for the kinematic group and 58 months for the mechanical group, no orthopedic complications or reoperations were recorded., Conclusion: Although this study has a small patient cohort, our results suggest that kinematic alignment for TKA after UKA revision is an attractive method. Further studies are warranted.
- Published
- 2016
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29. Study of Glycine and Folic Acid Supplementation to Ameliorate Transfusion Dependence in Congenital SLC25A38 Mutated Sideroblastic Anemia.
- Author
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LeBlanc MA, Bettle A, Berman JN, Price VE, Pambrun C, Yu Z, Tiller M, McMaster CR, and Fernandez CV
- Subjects
- Adolescent, Adult, Female, Humans, Male, Anemia, Sideroblastic genetics, Anemia, Sideroblastic therapy, Erythrocyte Transfusion, Folic Acid administration & dosage, Glycine administration & dosage, Mitochondrial Membrane Transport Proteins genetics, Mutation
- Abstract
Congenital sideroblastic anemia (CSA) is a hematological disorder characterized by the presence of ringed sideroblasts in bone marrow erythroid precursors. Mutations in the erythroid-specific glycine mitochondrial transporter gene SLC25A38 have been found in a subset of patients with transfusion-dependent congenital CSA. Further studies in a zebrafish model identified a promising ameliorative strategy with combined supplementation with glycine and folate. We tested this combination in three individuals with SLC25A38 CSA, with a primary objective to decrease red blood cell transfusion requirements. No significant impact was observed on transfusion requirements or any hematologic parameters., (© 2016 Wiley Periodicals, Inc.)
- Published
- 2016
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30. Kinematic TKA using navigation: Surgical technique and initial results.
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Hutt JR, LeBlanc MA, Massé V, Lavigne M, and Vendittoli PA
- Subjects
- Adult, Aged, Aged, 80 and over, Biomechanical Phenomena, Female, Follow-Up Studies, Humans, Ligaments, Articular surgery, Male, Middle Aged, Retrospective Studies, Arthroplasty, Replacement, Knee methods, Knee Joint surgery, Surgery, Computer-Assisted
- Abstract
Background: Kinematic alignment for total knee arthroplasty (TKA) may be one way of improving outcomes. Previous studies have either used patient-specific instrumentation, which adds cost, or standard instrumentation, which provides no intraoperative feedback on resection alignment., Hypothesis: To determine if computer navigation could reproduce native patient anatomy and simplify ligament balance during TKA whilst giving satisfactory improvements in functional scores at early follow-up., Materials and Methods: Computer navigation was used for kinematic distal femoral and proximal tibial cuts in 100 consecutive and unselected TKAs. Resections were modified only if measured angles fell outside a pre-defined safe range of combined coronal orientation within±3 degrees of neutral and/or independent femoral or tibial cuts within±5 degrees. Pre- and postoperative measurements of the hip-knee-ankle (HKA) angle, the lateral distal femoral angle (LDFA) and the medial proximal tibial angle (MPTA) were taken using long-leg standing radiographs. Clinical evaluation was with the WOMAC and KOOS scales., Results: Mean follow-up was 2.4 years (range 1.0-3.7, SD 0.8). The mean pre-op LDFA was 2.1 degrees valgus (9.2 valgus to 3.7 varus, SD 2.5) and 1.8 degrees valgus post-op (5.7 valgus to 4.2 varus, SD 2.0) (P=0.41). The mean pre-op MPTA was 3.0 degrees varus (10.6 valgus to 10.2 varus, SD 3.2) and 2.4 degrees varus post-op (4.0 valgus to 6.8 varus, SD 2.2) (P=0.03). The mean WOMAC score improved from 49.4 (29-85, SD 12.8) to 24.7 (0-73, SD 16.5) (P<0.001) and the mean KOOS score from 37.1 (7.2-77.2, SD 13.0) to 65.1 (26.8-100, SD 16) (P<0.001). Five knees (5%) required additional ligament release, four with valgus OA and one with varus OA. Two knees (2%) required lateral retinacular release for patellar tracking., Discussion: Computer navigation for kinematic TKA provides the operating surgeon with full control and feedback at each step, whilst also allowing partial correction of more extreme anatomy that might be unsuitable for recreation during TKA. This technique helps to preserve ligament isometry and produces satisfactory improvements in functional scores., Level of Evidence: IV (retrospective case series review)., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)
- Published
- 2016
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31. Optimizing 1-μs-Resolution Single-Molecule Force Spectroscopy on a Commercial Atomic Force Microscope.
- Author
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Edwards DT, Faulk JK, Sanders AW, Bull MS, Walder R, LeBlanc MA, Sousa MC, and Perkins TT
- Subjects
- Microscopy, Atomic Force methods, Spectrum Analysis methods
- Abstract
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is widely used to mechanically measure the folding and unfolding of proteins. However, the temporal resolution of a standard commercial cantilever is 50-1000 μs, masking rapid transitions and short-lived intermediates. Recently, SMFS with 0.7-μs temporal resolution was achieved using an ultrashort (L = 9 μm) cantilever on a custom-built, high-speed AFM. By micromachining such cantilevers with a focused ion beam, we optimized them for SMFS rather than tapping-mode imaging. To enhance usability and throughput, we detected the modified cantilevers on a commercial AFM retrofitted with a detection laser system featuring a 3-μm circular spot size. Moreover, individual cantilevers were reused over multiple days. The improved capabilities of the modified cantilevers for SMFS were showcased by unfolding a polyprotein, a popular biophysical assay. Specifically, these cantilevers maintained a 1-μs response time while eliminating cantilever ringing (Q ≅ 0.5). We therefore expect such cantilevers, along with the instrumentational improvements to detect them on a commercial AFM, to accelerate high-precision AFM-based SMFS studies.
- Published
- 2015
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32. Focused chemical genomics using zebrafish xenotransplantation as a pre-clinical therapeutic platform for T-cell acute lymphoblastic leukemia.
- Author
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Bentley VL, Veinotte CJ, Corkery DP, Pinder JB, LeBlanc MA, Bedard K, Weng AP, Berman JN, and Dellaire G
- Subjects
- Amyloid Precursor Protein Secretases antagonists & inhibitors, Animals, Cells, Cultured, Child, Disease Models, Animal, Drug Resistance, Neoplasm, Embryo, Nonmammalian cytology, Embryo, Nonmammalian metabolism, Enzyme Inhibitors pharmacology, Fluorescent Antibody Technique, HeLa Cells, Humans, PTEN Phosphohydrolase genetics, Phosphatidylinositol 3-Kinases genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma pathology, Proto-Oncogene Proteins c-akt genetics, Receptor, Notch1 genetics, Signal Transduction, Transplantation, Heterologous, Zebrafish growth & development, Zebrafish metabolism, Antineoplastic Agents pharmacology, Embryo, Nonmammalian drug effects, Genomics methods, Mutation genetics, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma drug therapy, Precursor T-Cell Lymphoblastic Leukemia-Lymphoma genetics, Zebrafish genetics
- Abstract
Cancer therapeutics is evolving to precision medicine, with the goal of matching targeted compounds with molecular aberrations underlying a patient's cancer. While murine models offer a pre-clinical tool, associated costs and time are not compatible with actionable patient-directed interventions. Using the paradigm of T-cell acute lymphoblastic leukemia, a high-risk disease with defined molecular underpinnings, we developed a zebrafish human cancer xenotransplantation model to inform therapeutic decisions. Using a focused chemical genomic approach, we demonstrate that xenografted cell lines harboring mutations in the NOTCH1 and PI3K/AKT pathways respond concordantly to their targeted therapies, patient-derived T-cell acute lymphoblastic leukemia can be successfully engrafted in zebrafish and specific drug responses can be quantitatively determined. Using this approach, we identified a mutation sensitive to γ-secretase inhibition in a xenograft from a child with T-cell acute lymphoblastic leukemia, confirmed by Sanger sequencing and validated as a gain-of-function NOTCH1 mutation. The zebrafish xenotransplantation platform provides a novel cost-effective means of tailoring leukemia therapy in real time., (Copyright© Ferrata Storti Foundation.)
- Published
- 2015
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33. Phenotypic overlap between familial exudative vitreoretinopathy and microcephaly, lymphedema, and chorioretinal dysplasia caused by KIF11 mutations.
- Author
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Robitaille JM, Gillett RM, LeBlanc MA, Gaston D, Nightingale M, Mackley MP, Parkash S, Hathaway J, Thomas A, Ells A, Traboulsi EI, Héon E, Roy M, Shalev S, Fernandez CV, MacGillivray C, Wallace K, Fahiminiya S, Majewski J, McMaster CR, and Bedard K
- Subjects
- Base Sequence, Child, Child, Preschool, DNA Mutational Analysis, Electrophysiology, Exons genetics, Eye Diseases, Hereditary, Facies, Familial Exudative Vitreoretinopathies, Female, Fluorescein Angiography, Humans, Lymphedema diagnosis, Male, Microcephaly diagnosis, Molecular Sequence Data, Pedigree, Phenotype, Polymerase Chain Reaction, Retinal Diseases diagnosis, Retinal Diseases genetics, Retinal Dysplasia diagnosis, Kinesins genetics, Lymphedema genetics, Microcephaly genetics, Mutation, Retinal Dysplasia genetics
- Abstract
Importance: Retinal detachment with avascularity of the peripheral retina, typically associated with familial exudative vitreoretinopathy (FEVR), can result from mutations in KIF11, a gene recently identified to cause microcephaly, lymphedema, and chorioretinal dysplasia (MLCRD) as well as chorioretinal dysplasia, microcephaly, and mental retardation (CDMMR). Ophthalmologists should be aware of the range of presentations for mutations in KIF11 because the phenotypic distinction between FEVR and MLCRD/CDMMR portends management implications in patients with these conditions., Objective: To identify gene mutations in patients who present with a FEVR phenotype and explore the spectrum of ocular and systemic abnormalities caused by KIF11 mutations in a cohort of patients with FEVR or microcephaly in conjunction with chorioretinopathy or FEVR., Design, Setting, and Participants: Clinical data and DNA were collected from each participant between 1998 and 2013 from the clinical practices of ophthalmologists and clinical geneticists internationally. Twenty-eight FEVR probands with diagnoses made by the referring physician and without a known FEVR gene mutation, and 3 with microcephaly and chorioretinopathy, were included. At least 1 patient in each pedigree manifested 1 or more of the following: macular dragging, partial retinal detachment, falciform folds, or total retinal detachment., Exposures: Whole-exome sequencing was conducted on affected members in multiplex pedigrees, and Sanger sequencing of the 22 exons of the KIF11 gene was performed on singletons. Clinical data and history were collected and reviewed., Main Outcomes and Measures: Identification of mutations in KIF11., Results: Four novel heterozygous KIF11 mutations and 1 previously published mutation were identified in probands with FEVR: p.A218Gfs*15, p.E470X, p.R221G, c.790-1G>T, and the previously described heterozygous p.R47X. Documentation of peripheral avascular areas on intravenous fluorescein angiography was possible in 2 probands with fibrovascular proliferation demonstrating phenotypic overlap with FEVR., Conclusions and Relevance: Mutations in KIF11 cause a broader spectrum of ocular disease than previously reported, including retinal detachment. The KIF11 gene likely plays a role in retinal vascular development and mutations in this gene can lead to clinical overlap with FEVR. Cases of FEVR should be carefully inspected for the presence of microcephaly as a marker for KIF11-related disease to enhance the accuracy of the prognosis and genetic counseling.
- Published
- 2014
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34. Germline mutations in MAP3K6 are associated with familial gastric cancer.
- Author
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Gaston D, Hansford S, Oliveira C, Nightingale M, Pinheiro H, Macgillivray C, Kaurah P, Rideout AL, Steele P, Soares G, Huang WY, Whitehouse S, Blowers S, LeBlanc MA, Jiang H, Greer W, Samuels ME, Orr A, Fernandez CV, Majewski J, Ludman M, Dyack S, Penney LS, McMaster CR, Huntsman D, and Bedard K
- Subjects
- Antigens, CD, Cadherins genetics, DNA Mutational Analysis, Female, Genetic Linkage, Genotype, Humans, Male, Pedigree, Polymorphism, Single Nucleotide, Stomach Neoplasms pathology, Genetic Predisposition to Disease, Germ-Line Mutation genetics, MAP Kinase Kinase Kinases genetics, Stomach Neoplasms genetics
- Abstract
Gastric cancer is among the leading causes of cancer-related deaths worldwide. While heritable forms of gastric cancer are relatively rare, identifying the genes responsible for such cases can inform diagnosis and treatment for both hereditary and sporadic cases of gastric cancer. Mutations in the E-cadherin gene, CDH1, account for 40% of the most common form of familial gastric cancer (FGC), hereditary diffuse gastric cancer (HDGC). The genes responsible for the remaining forms of FGC are currently unknown. Here we examined a large family from Maritime Canada with FGC without CDH1 mutations, and identified a germline coding variant (p.P946L) in mitogen-activated protein kinase kinase kinase 6 (MAP3K6). Based on conservation, predicted pathogenicity and a known role of the gene in cancer predisposition, MAP3K6 was considered a strong candidate and was investigated further. Screening of an additional 115 unrelated individuals with non-CDH1 FGC identified the p.P946L MAP3K6 variant, as well as four additional coding variants in MAP3K6 (p.F849Sfs*142, p.P958T, p.D200Y and p.V207G). A somatic second-hit variant (p.H506Y) was present in DNA obtained from one of the tumor specimens, and evidence of DNA hypermethylation within the MAP3K6 gene was observed in DNA from the tumor of another affected individual. These findings, together with previous evidence from mouse models that MAP3K6 acts as a tumor suppressor, and studies showing the presence of somatic mutations in MAP3K6 in non-hereditary gastric cancers and gastric cancer cell lines, point towards MAP3K6 variants as a predisposing factor for FGC.
- Published
- 2014
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35. Summary of 11 years of enteric outbreak investigations and criteria to initiate an investigation, Province of Quebec, 2002 through 2012.
- Author
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Gaulin C, Currie A, Gravel G, Hamel M, Leblanc MA, Ramsay D, and Bekal S
- Subjects
- Disease Outbreaks history, Escherichia coli Infections history, Escherichia coli Infections microbiology, Escherichia coli O157 isolation & purification, History, 21st Century, Humans, Listeria monocytogenes isolation & purification, Listeriosis history, Listeriosis microbiology, Odds Ratio, Quebec epidemiology, Retrospective Studies, Salmonella isolation & purification, Salmonella Infections history, Salmonella Infections microbiology, Escherichia coli Infections epidemiology, Escherichia coli O157 physiology, Listeria monocytogenes physiology, Listeriosis epidemiology, Salmonella physiology, Salmonella Infections epidemiology
- Abstract
This article presents a retrospective analysis of enteric disease outbreak investigations led by or conducted in collaboration with provincial health authorities in the Province of Quebec from 2002 through 2012. Objectives were to characterize enteric disease outbreaks, quantify and describe those for which a source was identified (including the control measures implemented), identify factors that contributed to or impeded identification of the source, and recommend areas for improvement in outbreak investigations (including establishment of criteria to initiate investigations). A descriptive analysis of enteric disease outbreak summaries recorded in a provincial database since 2002 was conducted, and corresponding outbreak reports were reviewed. Among 61 enteric disease outbreaks investigated, primary pathogens involved were Salmonella (46%), Escherichia coli O157:H7 (25%), and Listeria monocytogenes (13%). Sources were identified for 37 (61%) of 61 of the outbreaks, and descriptive studies were sufficient to identify the source for 26 (70%) of these. During the descriptive phase of the investigation, the causes of 21 (81%) of 26 outbreaks were identified by promptly collecting samples of suspected foods based on case interviews. Causes of outbreaks were more likely to be detected by weekly surveillance or alert systems (odds ratio = 6.0, P = 0.04) than by serotyping or molecular typing surveillance and were more likely to be associated with a common event or location (odds ratio = 11.0, P = 0.023). Among the 37 outbreaks for which causes were identified, 24 (65%) were associated with contaminated food, and recalls were the primary control measure implemented (54%). Review of enteric outbreaks investigated at the provincial level in Québec has increased the province's ability to quantify success and identify factors that can promote success. Multiple criteria should be taken into account to identify case clusters that are more likely to be resolved.
- Published
- 2014
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36. Prevalence and types of rectal douches used for anal intercourse: results from an international survey.
- Author
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Javanbakht M, Stahlman S, Pickett J, LeBlanc MA, and Gorbach PM
- Subjects
- Adult, Anti-Infective Agents therapeutic use, Cross-Sectional Studies, Female, HIV Infections epidemiology, HIV Seropositivity epidemiology, Humans, Internet, Male, Middle Aged, Odds Ratio, Prevalence, Regression Analysis, Risk Factors, Sexually Transmitted Diseases epidemiology, Surveys and Questionnaires, Young Adult, Anal Canal, Therapeutic Irrigation statistics & numerical data, Unsafe Sex statistics & numerical data
- Abstract
Background: Rectal products used with anal intercourse (AI) may facilitate transmission of STIs/HIV. However, there is limited data on rectal douching behavior in populations practicing AI. We examined the content, types of products, rectal douching practices and risk behaviors among those reporting AI., Methods: From August 2011 to May 2012, 1,725 women and men reporting receptive AI in the past 3 months completed an internet-based survey on rectal douching practices. The survey was available in English, French, German, Mandarin, Portuguese, Russian, Spanish, and Thai and included questions on sexual behaviors associated with AI including rectal douching. Differences by rectal douching practices were evaluated using chi-square methods and associations between reported douching practices and other factors including age and reported STI history were evaluated using logistic regression analysis., Results: Respondents represented 112 countries, were mostly male (88%), and from North America (55%) or Europe (22%). Among the 1,339 respondents (66%) who reported rectal douching, most (83%) reported always/almost always douching before receptive AI. The majority of rectal douchers reported using non-commercial/homemade products (93%), with water being the most commonly used product (82%). Commercial products were used by 31%, with the most common product being saline-based (56%). Rectal douching varied by demographic and risk behaviors. The prevalence of rectal douching was higher among men (70% vs. 32%; p-value < .01), those reporting substance-use with sex (74% vs. 46%; p-value < .01), and those reporting an STI in the past year (69% vs. 57% p-value < .01) or ever testing HIV-positive (72% vs. 53%; p-value < .01). In multivariable analysis, adjusting for age, gender, region, condom and lubricant use, substance use, and HIV-status, douchers had a 74% increased odds of reporting STI in the past year as compared to non-douchers [adjusted odds ratio (AOR) = 1.74; 95% CI 1.01-3.00]., Conclusion: Given that rectal douching before receptive AI is common and because rectal douching was associated with other sexual risk behaviors the contribution of this practice to the transmission and acquisition of STIs including HIV may be important.
- Published
- 2014
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37. A novel rearrangement of occludin causes brain calcification and renal dysfunction.
- Author
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LeBlanc MA, Penney LS, Gaston D, Shi Y, Aberg E, Nightingale M, Jiang H, Gillett RM, Fahiminiya S, Macgillivray C, Wood EP, Acott PD, Khan MN, Samuels ME, Majewski J, Orr A, McMaster CR, and Bedard K
- Subjects
- Canada, Child, Preschool, Chromosome Mapping, DNA Copy Number Variations, Exome, Exons, Female, Gene Deletion, Genotype, Homozygote, Humans, Introns, Malformations of Cortical Development genetics, Multiplex Polymerase Chain Reaction, Mutation, Occludin metabolism, Pedigree, Phenotype, Polymorphism, Single Nucleotide, RNA Splicing, Sequence Analysis, DNA, Brain physiopathology, Calcinosis physiopathology, Gene Rearrangement, Kidney physiopathology, Occludin genetics
- Abstract
Pediatric intracranial calcification may be caused by inherited or acquired factors. We describe the identification of a novel rearrangement in which a downstream pseudogene translocates into exon 9 of OCLN, resulting in band-like brain calcification and advanced chronic kidney disease in early childhood. SNP genotyping and read-depth variation from whole exome sequencing initially pointed to a mutation in the OCLN gene. The high degree of identity between OCLN and two pseudogenes required a combination of multiplex ligation-dependent probe amplification, PCR, and Sanger sequencing to identify the genomic rearrangement that was the underlying genetic cause of the disease. Mutations in exon 3, or at the 5-6 intron splice site, of OCLN have been reported to cause brain calcification and polymicrogyria with no evidence of extra-cranial phenotypes. Of the OCLN splice variants described, all make use of exon 9, while OCLN variants that use exons 3, 5, and 6 are tissue specific. The genetic rearrangement we identified in exon 9 provides a plausible explanation for the expanded clinical phenotype observed in our individuals. Furthermore, the lack of polymicrogyria associated with the rearrangement of OCLN in our patients extends the range of cranial defects that can be observed due to OCLN mutations.
- Published
- 2013
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38. Multiple outbreaks of gastroenteritis that were associated with 16 funerals and a unique caterer and spanned 6 days, 2011, Québec, Canada.
- Author
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Gaulin C, Nguon S, Leblanc MA, Ramsay D, and Roy S
- Subjects
- Caliciviridae Infections etiology, Caliciviridae Infections transmission, Cohort Studies, Diarrhea epidemiology, Disease Outbreaks, Food Microbiology, Foodborne Diseases etiology, Gastroenteritis etiology, Humans, Hygiene, Norovirus isolation & purification, Norovirus pathogenicity, Quebec epidemiology, Caliciviridae Infections epidemiology, Food Contamination analysis, Food Handling methods, Foodborne Diseases epidemiology, Gastroenteritis epidemiology
- Abstract
In January 2011, multiple acute gastroenteritis outbreaks that spanned many days and were related to attendance at funerals were reported to public health units in Quebec. An epidemiological investigation was initiated to identify the source of the contamination and to explain the extent of the contamination over time. Thirty-one cohorts of individuals attended different funerals held between 14 and 19 January. All attendees were served a cold buffet made by the same caterer. Of these 31 cohorts, 16 (with a total of about 800 people) contained individuals who reported being ill after the funeral. Symptoms were mainly diarrhea (89 to 94% of individuals), vomiting (63 to 90%,) and fever (26 to 39%), with a median incubation period of 29 to 33 h and a median duration of symptoms of 24 to 33 h, suggesting norovirus-like infection. Among the 16 cohorts, 3 were selected for cohort studies. Among those three cohorts, the mean illness rate was 68%. Associations were found between those who fell ill and those who had consumed pasta salad (relative risk [RR] = 2.4; P = 0.0022) and ham sandwiches (RR = 1.8; P = 0.0096). No food handlers reported being sick. No stool samples were provided by individuals who became ill. Environmental and food samples were all negative for causative agents. Although the causative agent was not clearly identified, this investigation raised many concerns about the importance of preventing foodborne transmission of viral gastroenteritis and generated some recommendations for management of similar outbreaks.
- Published
- 2013
- Full Text
- View/download PDF
39. The yeast oxysterol binding protein Kes1 maintains sphingolipid levels.
- Author
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LeBlanc MA, Fairn GD, Russo SB, Czyz O, Zaremberg V, Cowart LA, and McMaster CR
- Subjects
- Cell Membrane metabolism, Ceramides metabolism, Golgi Apparatus metabolism, Protein Transport, Proton-Translocating ATPases metabolism, Membrane Proteins metabolism, Receptors, Steroid metabolism, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Sphingolipids metabolism
- Abstract
The oxysterol binding protein family are amphitropic proteins that bind oxysterols, sterols, and possibly phosphoinositides, in a conserved binding pocket. The Saccharomyces cerevisiae oxysterol binding protein family member Kes1 (also known as Osh4) also binds phosphoinositides on a distinct surface of the protein from the conserved binding pocket. In this study, we determine that the oxysterol binding protein family member Kes1 is required to maintain the ratio of complex sphingolipids and levels of ceramide, sphingosine-phosphate and sphingosine. This inability to maintain normal sphingolipid homeostasis resulted in misdistribution of Pma1, a protein that requires normal sphingolipid synthesis to occur to partition into membrane rafts at the Golgi for its trafficking to the plasma membrane.
- Published
- 2013
- Full Text
- View/download PDF
40. Localization of lipid raft proteins to the plasma membrane is a major function of the phospholipid transfer protein Sec14.
- Author
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Curwin AJ, Leblanc MA, Fairn GD, and McMaster CR
- Subjects
- DNA Primers genetics, Gene Deletion, Microscopy, Electron, Mutation, Missense genetics, Phospholipid Transfer Proteins genetics, Plasmids genetics, Proteasome Endopeptidase Complex metabolism, Proton-Translocating ATPases metabolism, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae growth & development, Saccharomyces cerevisiae ultrastructure, Saccharomyces cerevisiae Proteins genetics, Temperature, Membrane Microdomains metabolism, Membrane Proteins metabolism, Phospholipid Transfer Proteins metabolism, Protein Transport physiology, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism
- Abstract
The Sec14 protein domain is a conserved tertiary structure that binds hydrophobic ligands. The Sec14 protein from Saccharomyces cerevisiae is essential with studies of S. cerevisiae Sec14 cellular function facilitated by a sole temperature sensitive allele, sec14(ts). The sec14(ts) allele encodes a protein with a point mutation resulting in a single amino acid change, Sec14(G266D). In this study results from a genome-wide genetic screen, and pharmacological data, provide evidence that the Sec14(G266D) protein is present at a reduced level compared to wild type Sec14 due to its being targeted to the proteosome. Increased expression of the sec14(ts) allele ameliorated growth arrest, but did not restore the defects in membrane accumulation or vesicular transport known to be defective in sec14(ts) cells. We determined that trafficking and localization of two well characterized lipid raft resident proteins, Pma1 and Fus-Mid-GFP, were aberrant in sec14(ts) cells. Localization of both lipid raft proteins was restored upon increased expression of the sec14(ts) allele. We suggest that a major function provided by Sec14 is trafficking and localization of lipid raft proteins.
- Published
- 2013
- Full Text
- View/download PDF
41. Is wetter better? An evaluation of over-the-counter personal lubricants for safety and anti-HIV-1 activity.
- Author
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Dezzutti CS, Brown ER, Moncla B, Russo J, Cost M, Wang L, Uranker K, Kunjara Na Ayudhya RP, Pryke K, Pickett J, Leblanc MA, and Rohan LC
- Subjects
- Anti-HIV Agents chemistry, Cell Line, Cell Survival drug effects, Cellulose analogs & derivatives, Cellulose chemistry, Cellulose pharmacology, Epithelial Cells drug effects, Epithelial Cells physiology, Female, Glycerol chemistry, Glycerol pharmacology, Humans, Lactobacillus drug effects, Lubricants chemistry, Microbial Viability drug effects, Mucous Membrane drug effects, Mucous Membrane pathology, Mucous Membrane virology, Nonprescription Drugs, Osmolar Concentration, Phosphates chemistry, Phosphates pharmacology, Propylene Glycols chemistry, Propylene Glycols pharmacology, Silicone Gels, Spermatocidal Agents chemistry, Spermatocidal Agents pharmacology, Viscosity, Anti-HIV Agents pharmacology, HIV Infections prevention & control, HIV-1 drug effects, Lubricants pharmacology
- Abstract
Because lubricants may decrease trauma during coitus, it is hypothesized that they could aid in the prevention of HIV acquisition. Therefore, safety and anti-HIV-1 activity of over-the-counter (OTC) aqueous- (n = 10), lipid- (n = 2), and silicone-based (n = 2) products were tested. The rheological properties of the lipid-based lubricants precluded testing with the exception of explant safety testing. Six aqueous-based gels were hyperosmolar, two were nearly iso-osmolar, and two were hypo-osmolar. Evaluation of the panel of products showed Gynol II (a spermicidal gel containing 2% nonoxynol-9), KY Jelly, and Replens were toxic to Lactobacillus. Two nearly iso-osmolar aqueous- and both silicone-based gels were not toxic toward epithelial cell lines or ectocervical or colorectal explant tissues. Hyperosmolar lubricants demonstrated reduction of tissue viability and epithelial fracture/sloughing while the nearly iso-osmolar and silicon-based lubricants showed no significant changes in tissue viability or epithelial modifications. While most of the lubricants had no measurable anti-HIV-1 activity, three lubricants which retained cell viability did demonstrate modest anti-HIV-1 activity in vitro. To determine if this would result in protection of mucosal tissue or conversely determine if the epithelial damage associated with the hyperosmolar lubricants increased HIV-1 infection ex vivo, ectocervical tissue was exposed to selected lubricants and then challenged with HIV-1. None of the lubricants that had a moderate to high therapeutic index protected the mucosal tissue. These results show hyperosmolar lubricant gels were associated with cellular toxicity and epithelial damage while showing no anti-viral activity. The two iso-osmolar lubricants, Good Clean Love and PRÉ, and both silicone-based lubricants, Female Condom 2 lubricant and Wet Platinum, were the safest in our testing algorithm.
- Published
- 2012
- Full Text
- View/download PDF
42. Coordination Chemistry of Polyaromatic Thiosemicarbazones 2: Synthesis and Biological Activity of Zinc, Cobalt, and Copper Complexes of 1-(Naphthalene-2-yl)ethanone Thiosemicarbazone.
- Author
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Leblanc MA, Gonzalez-Sarrías A, Beckford FA, Mbarushimana PC, and Seeram NP
- Abstract
A novel thiosemicarbazone from 2-acetonaphthone (represented as acnTSC) has been synthesized and its basic coordination chemistry with zinc(II), cobalt(II), and copper(II) explored. The complexes were characterized by elemental analysis and various spectroscopic techniques and are best formulated as [M(acnTSC)(2)Cl(2)] with the metal likely in an octahedral environment. The anticancer activity of the complexes was determined against a panel of human colon cancer cells (HCT-116 and Caco-2). The compounds bind to DNA via an intercalative mode with binding constants of 9.7 × 10(4) M(-1), 1.8 × 10(5) M(-1), and 9.5 × 10(4) M(-1) for the zinc, cobalt, and copper complexes, respectively.
- Published
- 2011
- Full Text
- View/download PDF
43. Lipid binding requirements for oxysterol-binding protein Kes1 inhibition of autophagy and endosome-trans-Golgi trafficking pathways.
- Author
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LeBlanc MA and McMaster CR
- Subjects
- Biological Transport, Cell Membrane metabolism, Cytoplasm metabolism, Glycerophospholipids chemistry, Golgi Apparatus metabolism, Liposomes chemistry, Phosphates chemistry, Phospholipids chemistry, Protein Binding, Saccharomyces cerevisiae metabolism, Autophagy, Endosomes metabolism, Lipids chemistry, Membrane Proteins metabolism, Receptors, Steroid metabolism, Saccharomyces cerevisiae Proteins metabolism, Sterols chemistry
- Abstract
The Saccharomyces cerevisiae protein Kes1/Osh4 is a member of the enigmatic family of oxysterol-binding proteins found throughout Eukarya united by a β-barrel structure that binds sterols and oxysterols. In this study, we determined that phosphoinositides are the major determinant in membranes that facilitate Kes1 association both in vitro and in cells. Increased expression of Kes1 in yeast cells decreased the levels of both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 3-phosphate (PI3P). Phosphoinositide and sterol bindings by Kes1 were necessary for Kes1 to decrease the level of PI4P but not PI3P. Kes1 inhibited vesicular trafficking between the trans-Golgi and plasma membrane as evidenced by accumulation of the vacuolar soluble NSF attachment protein receptors Snc1 in the cytoplasmic vesicles. Sterol and phosphoinositide binding by Kes1 both contributed to its regulation of Snc1 trafficking. This study also describes a previously unknown role for Kes1 in the regulation of the autophagy/cytoplasm to the vacuole trafficking pathway. The Kes1-mediated regulation of the autophagy/cytoplasm to the vacuole trafficking pathway was prevented by increasing expression of the PI3K Vps34, suggesting that it is the Kes1-mediated decrease in PI3P level that contributes to this regulation.
- Published
- 2010
- Full Text
- View/download PDF
44. Surprising roles for phospholipid binding proteins revealed by high throughput genetics.
- Author
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LeBlanc MA and McMaster CR
- Subjects
- Animals, Biological Transport genetics, Carrier Proteins analysis, Carrier Proteins genetics, Carrier Proteins metabolism, Golgi Apparatus metabolism, Humans, Membrane Proteins analysis, Membrane Proteins genetics, Membrane Proteins metabolism, Models, Biological, Phospholipid Transfer Proteins genetics, Phospholipid Transfer Proteins metabolism, Phospholipid Transfer Proteins physiology, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins genetics, Saccharomyces cerevisiae Proteins metabolism, Saccharomyces cerevisiae Proteins physiology, Carrier Proteins physiology, Genetic Techniques, High-Throughput Screening Assays methods, Membrane Proteins physiology, Phospholipids metabolism
- Abstract
Saccharomyces cerevisiae remains an ideal organism for studying the cell biological roles of lipids in vivo, as yeast has phospholipid metabolic pathways similar to mammalian cells, is easy and economical to manipulate, and is genetically tractable. The availability of isogenic strains containing specific genetic inactivation of each non-essential gene allowed for the development of a high-throughput method, called synthetic genetic analysis (SGA), to identify and describe precise pathways or functions associated with specific genes. This review describes the use of SGA to aid in elucidating the function of two lipid-binding proteins that regulate vesicular transport, Sec14 and Kes1. Sec14 was first identified as a phosphatidylcholine (PC) - phosphatidylinositol (PI) transfer protein required for viability, with reduced Sec14 function resulting in diminished vesicular transport out of the trans-Golgi. Although Sec14 is required for cell viability, inactivating the KES1 gene that encodes for a member of the oxysterol binding protein family in cells lacking Sec14 function results in restoration of vesicular transport and cell growth. SGA analysis identified a role for Kes1 and Sec14 in regulating the level and function of Golgi PI-4-phosphate (PI-4-P). SGA also determined that Sec14 not only regulates vesicular transport out of the trans-Golgi, but also transport from endosomes to the trans-Golgi. Comparing SGA screens in databases, coupled with genetic and cell biological analyses, further determined that the PI-4-P pool affected by Kes1 is generated by the PI 4-kinase Pik1. An important biological role for Sec14 and Kes1 revealed by SGA is coordinate regulation of the Pik1-generated Golgi PI-4-P pool that in turn is essential for vesicular transport into and out of the trans-Golgi.
- Published
- 2010
- Full Text
- View/download PDF
45. Preference and practices relating to lubricant use during anal intercourse: implications for rectal microbicides.
- Author
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Javanbakht M, Murphy R, Gorbach P, LeBlanc MA, and Pickett J
- Subjects
- Administration, Rectal, Adult, Anal Canal, Coitus, Confidence Intervals, Female, Humans, Male, Middle Aged, Odds Ratio, Sexually Transmitted Diseases, Viral prevention & control, Surveys and Questionnaires, Young Adult, Anti-Infective Agents, Local administration & dosage, Health Knowledge, Attitudes, Practice, Lubricants administration & dosage, Lubrication methods, Sexual Behavior statistics & numerical data
- Abstract
Background: The importance of the acceptability of rectal microbicides for HIV and sexually transmissible infections (STIs) prevention is widely recognised. Given relatively consistent use of lubricants for anal intercourse (AI) and the potential for lubricant-like rectal microbicides, understanding barriers to lubricant use may help inform hurdles likely to be encountered once a rectal microbicide becomes available., Methods: We conducted an internet-based survey using a 25-item questionnaire to assess AI and lubricant use, including lubricant preferences and barriers to use., Results: The majority of the 6124 respondents who reported AI were male (93%), 25 years or older (80%) and from North America (70%). Consistent condom use during AI was reported by a minority (35%) and consistent lubricant use was reported by over half of respondents. Reasons for non-use differed by age and region. Among men, those <25 years were more likely to report barriers around cost compared with those 45 and older (odds ratio (OR) = 6.64; 95% confidence interval (CI) 3.14-14.03). European men (OR = 1.92; 95% CI 1.50-2.45), Latin American women (OR = 3.69; 95% CI 1.27-10.75) and Asian women (OR = 4.04; 95% CI 1.39-11.78) were more likely to report sexual preference as a reason for non-use., Conclusions: Rectal lubricants are widely used, but barriers to use vary by age and region for dry sex. A lubricant-like rectal microbicide would potentially be acceptable and such a product may be useful as a method of HIV prevention. However, targeted marketing and educational approaches may be needed to enhance use and acceptability of such a product.
- Published
- 2010
- Full Text
- View/download PDF
46. Can studies of cognitive abilities and of life in the wild really help us to understand equine learning?
- Author
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Leblanc MA and Duncan P
- Subjects
- Animal Husbandry, Animals, Animals, Domestic, Animals, Wild, Behavior, Animal physiology, Cognition physiology, Ethics, Research, Horses physiology, Horses psychology, Learning physiology, Research Design
- Published
- 2007
- Full Text
- View/download PDF
47. Investigation of the dB/dH effect using trapped flux in type-II superconductors.
- Author
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LeBlanc MA, Wang SX, LeBlanc D, Krzywinski M, and Meng J
- Published
- 1995
- Full Text
- View/download PDF
48. [Prevalence of latex allergy among personnel at a hospital].
- Author
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Dousson C, Ripault B, Leblanc MA, Le Sellin J, Levaux MM, Jeanson S, Sabbah A, and Penneau-Fontbonne D
- Subjects
- Adult, Cross Reactions, Dermatitis, Allergic Contact epidemiology, Dermatitis, Allergic Contact etiology, Drug Eruptions diagnosis, Drug Eruptions etiology, Eczema, Dyshidrotic epidemiology, Eczema, Dyshidrotic etiology, Female, France epidemiology, Gloves, Surgical, Hospital Administrators, Hospitals, University, Humans, Hypersensitivity, Immediate epidemiology, Male, Nurses, Nursing Assistants, Occupational Diseases chemically induced, Predictive Value of Tests, Prevalence, Urticaria chemically induced, Urticaria epidemiology, Allergens, Drug Eruptions epidemiology, Latex adverse effects, Occupational Diseases epidemiology, Personnel, Hospital
- Abstract
The aim of this study was to compile a register of all the employees of a University Hospital Centre who complained of dermatosis of the hands due to latex. Recruitment was made by their spontaneous presentation in the service of the Workers Doctor (Médecine de Travail). The prevalence of clinical signs of contact eczema or professional urticaria is 2.3% for all personnel. 2.7% for nurses, 4.4% for care assistants or ancillary staff of the hospital service. In this population, 73% of subjects have shown previous atopy. The positive predictive value of the allergy tests was 51.3%, 2.32% of ASH-ASI, 1.75% of AS, 1.47% of IDE were allergic to latex, about 1.06% of the total personnel. 80% had atopy and 36.66% had a crossed allergy (banana, kiwi, avocat, pollen). Prevalence was zero amongst the administrative officers, but not systematic enquiry was made in the professional category. The orthoergical dermatoses were more frequent amongst the ASH-ASI, though the positive predictive value of tests was less. The considerable exposure to a number of caustic substances, as well as absence of precautions such as rinsing and drying of hands may explain this. All employees with allergy to latex have been declared to have a professional illness a card that mentions this allergy has been given to them.
- Published
- 1994
49. Critical-state-model parameters of polycrystalline YBa2Cu3O7: Critical current in thin slabs and field penetration in hollow cylinders.
- Author
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Fournier P, Aubin M, and LeBlanc MA
- Published
- 1994
- Full Text
- View/download PDF
50. Flux-trapping phenomena in sintered tubes of high-Tc superconductors.
- Author
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Çelebi S and LeBlanc MA
- Published
- 1994
- Full Text
- View/download PDF
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