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Lecinski S, Shepherd JW, Bunting K, Dresser L, Quinn SD, MacDonald C, Leake MC. Correlating viscosity and molecular crowding with fluorescent nanobeads and molecular probes: in vitro and in vivo. Interface Focus 2022; 12:20220042. [PMID: 36330320 PMCID: PMC9560789 DOI: 10.1098/rsfs.2022.0042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/05/2022] [Indexed: 02/02/2023] Open
Abstract
In eukaryotes, intracellular physico-chemical properties like macromolecular crowding and cytoplasmic viscoelasticity influence key processes such as metabolic activities, molecular diffusion and protein folding. However, mapping crowding and viscoelasticity in living cells remains challenging. One approach uses passive rheology in which diffusion of exogenous fluorescent particles internalized in cells is tracked and physico-chemical properties inferred from derived mean square displacement relations. Recently, the crGE2.3 Förster resonance energy transfer biosensor was developed to quantify crowding in cells, though it is unclear how this readout depends on viscoelasticity and the molecular weight of the crowder. Here, we present correlative, multi-dimensional data to explore diffusion and molecular crowding characteristics of molecular crowding agents using super-resolved fluorescence microscopy and ensemble time-resolved spectroscopy. We firstly characterize in vitro and then apply these insights to live cells of budding yeast Saccharomyces cerevisiae. It is to our knowledge the first time this has been attempted. We demonstrate that these are usable both in vitro and in the case of endogenously expressed sensors in live cells. Finally, we present a method to internalize fluorescent beads as in situ viscoelasticity markers in the cytoplasm of live yeast cells and discuss limitations of this approach including impairment of cellular function.
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Affiliation(s)
- Sarah Lecinski
- Department of Physics, University of York, York YO10 5DD, UK
| | - Jack W. Shepherd
- Department of Physics, University of York, York YO10 5DD, UK
- Department of Biology, University of York, York YO10 5DD, UK
| | - Kate Bunting
- Department of Biology, University of York, York YO10 5DD, UK
| | - Lara Dresser
- Department of Physics, University of York, York YO10 5DD, UK
| | - Steven D. Quinn
- Department of Physics, University of York, York YO10 5DD, UK
| | - Chris MacDonald
- Department of Biology, University of York, York YO10 5DD, UK
| | - Mark C. Leake
- Department of Physics, University of York, York YO10 5DD, UK
- Department of Biology, University of York, York YO10 5DD, UK
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2
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Quinn SD, Dresser L, Graham S, Conteduca D, Shepherd J, Leake MC. Crowding-induced morphological changes in synthetic lipid vesicles determined using smFRET. Front Bioeng Biotechnol 2022; 10:958026. [PMID: 36394015 PMCID: PMC9650091 DOI: 10.3389/fbioe.2022.958026] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/13/2022] [Indexed: 12/02/2022] Open
Abstract
Lipid vesicles are valuable mesoscale molecular confinement vessels for studying membrane mechanics and lipid–protein interactions, and they have found utility among bio-inspired technologies, including drug delivery vehicles. While vesicle morphology can be modified by changing the lipid composition and introducing fusion or pore-forming proteins and detergents, the influence of extramembrane crowding on vesicle morphology has remained under-explored owing to a lack of experimental tools capable of capturing morphological changes on the nanoscale. Here, we use biocompatible polymers to simulate molecular crowding in vitro, and through combinations of FRET spectroscopy, lifetime analysis, dynamic light scattering, and single-vesicle imaging, we characterize how crowding regulates vesicle morphology. We show that both freely diffusing and surface-tethered vesicles fluorescently tagged with the DiI and DiD FRET pair undergo compaction in response to modest concentrations of sorbitol, polyethylene glycol, and Ficoll. A striking observation is that sorbitol results in irreversible compaction, whereas the influence of high molecular weight PEG-based crowders was found to be reversible. Regulation of molecular crowding allows for precise control of the vesicle architecture in vitro, with vast implications for drug delivery and vesicle trafficking systems. Furthermore, our observations of vesicle compaction may also serve to act as a mechanosensitive readout of extramembrane crowding.
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Affiliation(s)
- Steven D. Quinn
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
| | - Lara Dresser
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Sarah Graham
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Donato Conteduca
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
| | - Jack Shepherd
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- Department of Biology, University of York, York, United Kingdom
| | - Mark C. Leake
- School of Physics, Engineering and Technology, University of York, York, United Kingdom
- York Biomedical Research Institute, University of York, York, United Kingdom
- Department of Biology, University of York, York, United Kingdom
- *Correspondence: Mark C. Leake,
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Dresser L, Graham SP, Miller LM, Schaefer C, Conteduca D, Johnson S, Leake MC, Quinn SD. Tween-20 Induces the Structural Remodeling of Single Lipid Vesicles. J Phys Chem Lett 2022; 13:5341-5350. [PMID: 35678387 PMCID: PMC9208007 DOI: 10.1021/acs.jpclett.2c00704] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/31/2022] [Indexed: 05/04/2023]
Abstract
The solubilization of lipid membranes by Tween-20 is crucial for a number of biotechnological applications, but the mechanistic details remain elusive. Evidence from ensemble assays supports a solubilization model that encompasses surfactant association with the membrane and the release of mixed micelles to solution, but whether this process also involves intermediate transitions between regimes is unanswered. In search of mechanistic origins, increasing focus is placed on identifying Tween-20 interactions with controllable membrane mimetics. Here, we employed ultrasensitive biosensing approaches, including single-vesicle spectroscopy based on fluorescence and energy transfer from membrane-encapsulated molecules, to interrogate interactions between Tween-20 and submicrometer-sized vesicles below the optical diffraction limit. We discovered that Tween-20, even at concentrations below the critical micellar concentration, triggers stepwise and phase-dependent structural remodeling events, including permeabilization and swelling, in both freely diffusing and surface-tethered vesicles, highlighting the substantial impact the surfactant has on vesicle conformation and stability prior to lysis.
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Affiliation(s)
- Lara Dresser
- Department
of Physics, University of York, York YO10 5DD, U.K.
| | - Sarah P. Graham
- Department
of Physics, University of York, York YO10 5DD, U.K.
| | - Lisa M. Miller
- Department
of Electronic Engineering, University of
York, York YO10 5DD, U.K.
| | | | | | - Steven Johnson
- Department
of Electronic Engineering, University of
York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
| | - Mark C. Leake
- Department
of Physics, University of York, York YO10 5DD, U.K.
- Department
of Biology, University of York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
| | - Steven D. Quinn
- Department
of Physics, University of York, York YO10 5DD, U.K.
- York
Biomedical Research Institute, University
of York, York YO10 5DD, U.K.
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Juan-Colás J, Dresser L, Morris K, Lagadou H, Ward RH, Burns A, Tear S, Johnson S, Leake MC, Quinn SD. The Mechanism of Vesicle Solubilization by the Detergent Sodium Dodecyl Sulfate. Langmuir 2020; 36:11499-11507. [PMID: 32870686 DOI: 10.1021/acs.langmuir.0c01810] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Membrane solubilization by sodium dodecyl sulfate (SDS) is indispensable for many established biotechnological applications, including viral inactivation and protein extraction. Although the ensemble thermodynamics have been thoroughly explored, the underlying molecular dynamics have remained inaccessible, owing to major limitations of traditional measurement tools. Here, we integrate multiple advanced biophysical approaches to gain multiangle insight into the time-dependence and fundamental kinetic steps associated with the solubilization of single submicron sized vesicles in response to SDS. We find that the accumulation of SDS molecules on intact vesicles triggers biphasic solubilization kinetics comprising an initial vesicle expansion event followed by rapid lipid loss and micellization. Our findings support a general mechanism of detergent-induced membrane solubilization, and we expect that the framework of correlative biophysical technologies presented here will form a general platform for elucidating the complex kinetics of membrane perturbation induced by a wide variety of surfactants and disrupting agents.
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Affiliation(s)
- José Juan-Colás
- Department of Electronic Engineering, University of York, Heslington, York YO10 5DD, U.K
| | - Lara Dresser
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Katie Morris
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Hugo Lagadou
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Rebecca H Ward
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Amy Burns
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Steve Tear
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
| | - Steven Johnson
- Department of Electronic Engineering, University of York, Heslington, York YO10 5DD, U.K
- York Biomedical Research Institute, University of York, Heslington, York YO10 5DD, U.K
| | - Mark C Leake
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
- Department of Biology, University of York, Heslington, York YO10 5DD, U.K
- York Biomedical Research Institute, University of York, Heslington, York YO10 5DD, U.K
| | - Steven D Quinn
- Department of Physics, University of York, Heslington, York YO10 5DD, U.K
- York Biomedical Research Institute, University of York, Heslington, York YO10 5DD, U.K
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Dresser L, Hunter P, Yendybayeva F, Hargreaves AL, Howard JAL, Evans GJO, Leake MC, Quinn SD. Amyloid-β oligomerization monitored by single-molecule stepwise photobleaching. Methods 2020; 193:80-95. [PMID: 32544592 PMCID: PMC8336786 DOI: 10.1016/j.ymeth.2020.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/02/2020] [Accepted: 06/10/2020] [Indexed: 01/19/2023] Open
Abstract
Method enables investigation of amyloid-β oligomer stoichiometry without requiring extrinsic fluorescent probes. Uses single-molecule stepwise photobleaching in vitro. Unveils heterogeneity within populations of oligomers. Assays oligomer-induced dysregulation of intracellular Ca2+ homeostasis in living cells.
A major hallmark of Alzheimer’s disease is the misfolding and aggregation of the amyloid- β peptide (Aβ). While early research pointed towards large fibrillar- and plaque-like aggregates as being the most toxic species, recent evidence now implicates small soluble Aβ oligomers as being orders of magnitude more harmful. Techniques capable of characterizing oligomer stoichiometry and assembly are thus critical for a deeper understanding of the earliest stages of neurodegeneration and for rationally testing next-generation oligomer inhibitors. While the fluorescence response of extrinsic fluorescent probes such as Thioflavin-T have become workhorse tools for characterizing large Aβ aggregates in solution, it is widely accepted that these methods suffer from many important drawbacks, including an insensitivity to oligomeric species. Here, we integrate several biophysics techniques to gain new insight into oligomer formation at the single-molecule level. We showcase single-molecule stepwise photobleaching of fluorescent dye molecules as a powerful method to bypass many of the traditional limitations, and provide a step-by-step guide to implementing the technique in vitro. By collecting fluorescence emission from single Aβ(1–42) peptides labelled at the N-terminal position with HiLyte Fluor 555 via wide-field total internal reflection fluorescence (TIRF) imaging, we demonstrate how to characterize the number of peptides per single immobile oligomer and reveal heterogeneity within sample populations. Importantly, fluorescence emerging from Aβ oligomers cannot be easily investigated using diffraction-limited optical microscopy tools. To assay oligomer activity, we also demonstrate the implementation of another biophysical method involving the ratiometric imaging of Fura-2-AM loaded cells which quantifies the rate of oligomer-induced dysregulation of intracellular Ca2+ homeostasis. We anticipate that the integrated single-molecule biophysics approaches highlighted here will develop further and in principle may be extended to the investigation of other protein aggregation systems under controlled experimental conditions.
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Affiliation(s)
- Lara Dresser
- Department of Physics, University of York, Heslington YO10 5DD, UK
| | - Patrick Hunter
- Department of Physics, University of York, Heslington YO10 5DD, UK
| | | | - Alex L Hargreaves
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK
| | - Jamieson A L Howard
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK
| | - Gareth J O Evans
- Department of Biology, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK
| | - Mark C Leake
- Department of Physics, University of York, Heslington YO10 5DD, UK; Department of Biology, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK
| | - Steven D Quinn
- Department of Physics, University of York, Heslington YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington YO10 5DD, UK.
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Morris AM, Rennert-May E, Dalton B, Daneman N, Dresser L, Fanella S, Grant J, Keynan Y, Le Saux N, McDonald J, Shevchuk Y, Thirion D, Conly JM. Rationale and development of a business case for antimicrobial stewardship programs in acute care hospital settings. Antimicrob Resist Infect Control 2018; 7:104. [PMID: 30181869 PMCID: PMC6114185 DOI: 10.1186/s13756-018-0396-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 08/21/2018] [Indexed: 11/27/2022] Open
Abstract
Background Antimicrobial stewardship programs (ASPs) have been shown to reduce inappropriate antimicrobial use and its consequences. However, these programs lack legislative requirements in many places and it can be difficult to determine what human resources are required for these programs and how to create a business case to present to hospital administrators for program funding. The objectives of the current paper were to review legislative requirements and outline human resource requirements for ASPs, and to create a base business case for ASPs. Methods A working group of antimicrobial stewardship experts from across Canada met to discuss the necessary components for creation of a business case for antimicrobial stewardship. A narrative review of the literature of the regulatory requirements and human resource recommendations for ASPs was conducted. Informed by the review and using a consensus decision-making process, the expert working group developed human resource recommendations based on a 1000 bed acute care health care facility in Canada. A spreadsheet based business case model for ASPs was also created. Results Legislative and /or regulatory requirements for ASPs were found in 2 countries and one state jurisdiction. The literature review and consensus development process recommended the following minimum human resources complement: 1 physician, 3 pharmacists, 0.5 program administrative and coordination support, and 0.4 data analyst support as full time equivalents (FTEs) per 1000 acute care beds. Necessary components for the business case model, including the human resource requirements, were determined to create a spreadsheet based model. Conclusions There is evidence to support the negative outcomes of inappropriate antimicrobial use as well as the benefits of ASPs. Legislative and /or regulatory requirements for ASPs are not common. The available evidence for human resource recommendations for ASPs using a narrative review process was examined and a base business case modelling scenario was created. As regulatory requirements for ASPs increase, it will be necessary to create accurate business cases for ASPs in order to obtain the necessary funding to render these programs successful. Electronic supplementary material The online version of this article (10.1186/s13756-018-0396-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- A M Morris
- 1Department of Medicine, University of Toronto, Sinai Health System, and University Health Network, Toronto, ON Canada
| | - E Rennert-May
- 2Department of Medicine, University of Calgary and Foothills Medical Centre, Alberta Health Services, Calgary, AB Canada
| | - B Dalton
- Pharmacy Services, Foothills Medical Centre, Alberta Health Services, Calgary, AB Canada
| | - N Daneman
- 4Department of Medicine, University of Toronto and Sunnybrook Health Sciences Centre, Toronto, ON Canada
| | - L Dresser
- 5Antimicrobial Stewardship, University Health Network, Toronto, ON Canada
| | - S Fanella
- 6Department of Pediatrics and Child Health and Medical Microbiology, University of Manitoba, Winnipeg, MB Canada
| | - J Grant
- 7Department of Pathology and Laboratory Medicine, Vancouver General Hospital, Vancouver, BC Canada
| | - Y Keynan
- 8Departments of Internal Medicine, Medical Microbiology and National Collaborating Center for Infectious Diseases, University of Manitoba, Winnipeg, MB Canada
| | - N Le Saux
- 9Department of Pediatrics, University of Ottawa and Children's Hospital of Eastern Ontario, Ottawa, ON Canada
| | - J McDonald
- 10Pharmacy Services, Children's Hospital of Eastern Ontario, Ottawa, ON Canada
| | - Y Shevchuk
- 11College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK Canada
| | - D Thirion
- 12Faculté de pharmacie, Université de Montréal, Department of Pharmacy, McGill University Health Centre, Montréal, QC Canada
| | - J M Conly
- 13Departments of Medicine and Immunology, Microbiology & Infectious Diseases, University of Calgary and Alberta Health Services, AGW5 Ground Floor SSB, Foothills Medical Centre, 1403 29 St NW, Calgary, AB T2N 2T9 Canada
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Bast DJ, Dresser L, Duncan CL, Walker SE, Mandell LA, Low DE, de Azavedo JCS. Short-Course Therapy of Gemifloxacin Effective Against Pneumococcal Pneumonia in Mice. J Chemother 2013; 18:634-40. [PMID: 17267342 DOI: 10.1179/joc.2006.18.6.634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Standard 7-14 day (d) courses of antimicrobial therapy for community-acquired pneumonia (CAP) are thought to have contributed to the emergence of resistant pneumoccoci. Consequently, short-course fluoroquinolone regimens have been proposed to minimize resistance. To test this, we examined 2-day versus 5-day regimens of gemifloxacin and levofloxacin for treatment of pneumonia in a murine model. In doing so, we also investigated whether the enhanced potency of gemifloxacin would influence outcomes. CD1 Swiss mice were infected intratracheally with 10(5)-CFU of a virulent Streptococcus pneumoniae strain. Drugs were administered every 8 h for 2 d and 5 d, starting at 24 h postinfection. Temperature was used to assess disease progression. Gemifloxacin remained effective for 2 d and 5 d, with survival rates of 100%-83% compared with 40%-58% for levofloxacin. Eighty-nine to 100% of gemifloxacin-treated mice were clear of pulmonary bacteria compared with only 0%-20% for levofloxacin. For levofloxacin-treated mice, 2 of 7 (29%) isolates with a levofloxacin minimum inhibitory concentration (MIC) 4 times that of the infecting parent strain had ParC mutations. By contrast, no isolates recovered from gemifloxacin-treated mice were reduced in susceptibility. Gemifloxacin could be effective in shortening duration of therapy for CAP treatment as well as minimize resistance development.
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Affiliation(s)
- D J Bast
- Department of Microbiology, Mount Sinai Hospital, Toronto, Ontario, Canada
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De Azavedo JCS, Dresser L, Duncan CL, Walker SE, Low DE, Bast DJ. Antipneumococcal activity of ertapenem compared with gatifloxacin in a temperature-sensitive murine model of acute pneumonia. J Chemother 2007; 19:392-7. [PMID: 17855183 DOI: 10.1179/joc.2007.19.4.392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Fluoroquinolone-resistance among pneumococci is low; however the number of isolates with a single ParC mutation has increased. Consequently, more potent agents are needed to minimize resistance selection. We investigated the efficacy of ertapenem versus gatifloxacin in a temperature-sensitive mouse model of pneumonia caused by a wildtype Streptococcus pneumoniae strain (A66) and an isogenic mutant with a ParC mutation (R222). Treatment started at 24 h and lasted for 5 days. Temperature was used to assess disease progression before and during treatment. Of mice infected with either strain and treated at an early stage of infection, 79-94% of those given ertapenem survived compared with 56-61% given gatifloxacin. If treated at a later stage, the results were similar for ertapenem (71-84%) but were considerably lower for gatifloxacin (17-33%). Ertapenem was as bactericidal as gatifloxacin against A66 (94-100% vs 92-100%) but was superior to gatifloxacin against R222 (95-100% vs 50-77%). Ertapenem is a promising new treatment for patients with pneumococcal pneumonia, including those at risk of infection with a fluoroquinolone-resistant strain.
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Affiliation(s)
- J C S De Azavedo
- Toronto Centre for Antimicrobial Research and Evaluation (ToCare), Mount Sinai Hospital, Canada.
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Muller MP, Richardson SE, McGeer A, Dresser L, Raboud J, Mazzulli T, Loeb M, Louie M. Early diagnosis of SARS: lessons from the Toronto SARS outbreak. Eur J Clin Microbiol Infect Dis 2006; 25:230-7. [PMID: 16586072 PMCID: PMC7087683 DOI: 10.1007/s10096-006-0127-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The clinical presentation of SARS is nonspecific and diagnostic tests do not provide accurate results early in the disease course. Initial diagnosis remains reliant on clinical assessment. To identify features of the clinical assessment that are useful in SARS diagnosis, the exposure status and the prevalence and timing of symptoms, signs, laboratory and radiographic findings were determined for all adult patients admitted with suspected SARS during the Toronto SARS outbreak. Findings were compared between patients with laboratory-confirmed SARS and those in whom SARS was excluded by laboratory or public health investigation. Of 364 cases, 273 (75%) had confirmed SARS, 30 (8%) were excluded, and 61 (17%) remained indeterminate. Among confirmed cases, exposure occurred in the healthcare environment (80%) or in the households of affected patients (17%); community or travel-related cases were rare (<3%). Fever occurred in 97% of patients by the time of admission. Respiratory findings including cough, dyspnea and pulmonary infiltrates evolved later and were present in only 59, 37 and 68% of patients, respectively, at admission. Direct exposure, fever on the first day of illness, and elevated temperature, pulmonary infiltrates, lymphopenia and thrombocytopenia at admission were associated with confirmed cases. Rhinorrhea, sore throat, and an elevated neutrophil count at admission were associated with excluded cases. In the absence of fever or significant exposure, SARS is unlikely. Other clinical, laboratory and radiographic findings further raise or lower the likelihood of SARS and provide a rational basis for estimating the likelihood of SARS and directing initial management.
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Affiliation(s)
- M P Muller
- Department of Microbiology, Mount Sinai Hospital, 600 University Avenue, M5G 1X5 Toronto, Canada.
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Bast DJ, Yue M, Chen X, Bell D, Dresser L, Saskin R, Mandell LA, Low DE, de Azavedo JCS. Novel murine model of pneumococcal pneumonia: use of temperature as a measure of disease severity to compare the efficacies of moxifloxacin and levofloxacin. Antimicrob Agents Chemother 2004; 48:3343-8. [PMID: 15328095 PMCID: PMC514736 DOI: 10.1128/aac.48.9.3343-3348.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 03/04/2004] [Accepted: 04/22/2004] [Indexed: 11/20/2022] Open
Abstract
Surface temperature measured by an infrared temperature-scanning thermometer was used to evaluate disease severity and predict imminent death in a murine model of pneumococcal pneumonia. We showed that a decrease in temperature was associated with increasing severity of disease and concomitant histological changes and also that a temperature of 30 degrees C or less was a predictor of death. Furthermore, viable bacterial counts in the lungs of mice euthanized at a temperature of < or = 30 degrees C were not significantly different from those seen in the lungs of mice allowed to die without intervention. These data support temperature change as a more subtle indicator of outcome than death and demonstrate that this could be used as a reliable end point for euthanasia. To test the utility of our model in a drug trial, we examined the efficacies of moxifloxacin and levofloxacin by using temperature as a measure of disease severity prior to and during treatment. Regardless of the antibiotic used, mice assessed as moderately ill (temperature > or = 32 degrees C) at the start of treatment had better clinical and bacteriological outcomes than mice assessed as severely ill (temperature < 32 degrees C). However, moxifloxacin offered better protection and greater bacterial clearance than did levofloxacin in all infected mice independent of disease severity. This model not only allows a more subtle evaluation of drug efficacy but also ensures a better degree of standardization and a more humane approach to drug efficacy studies involving animals.
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Affiliation(s)
- Darrin J Bast
- Toronto Centre for Antimicrobial Research and Evaluation, Room 1483, Mount Sinai Hospital, 600 University Ave., Toronto, Ontario M5G 1X5, Canada.
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