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Abstract
INTRODUCTION The dramatic impact of COVID-19 on humans worldwide has initiated an extraordinary search for effective treatment approaches. One of these is the administration of exogenous surfactant, which is being tested in ongoing clinical trials. AREAS COVERED Exogenous surfactant is a life-saving treatment for premature infants with neonatal respiratory distress syndrome. This treatment has also been tested for acute respiratory distress syndrome (ARDS) with limited success possibly due to the complexity of that syndrome. The 60-year history of successes and failures associated with surfactant therapy distinguishes it from many other treatments currently being tested for COVID-19 and provides the opportunity to discuss the factors that may influence the success of this therapy. EXPERT OPINION Clinical data provide a strong rationale for using exogenous surfactant in COVID-19 patients. Success of this therapy may be influenced by the mechanical ventilation strategy, the timing of treatment, the doses delivered, the method of delivery and the preparations utilized. In addition, future development of enhanced preparations may improve this treatment approach. Overall, results from ongoing trials may not only provide data to indicate if this therapy is effective for COVID-19 patients, but also lead to further scientific understanding and improved treatment strategies.
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Affiliation(s)
- Ruud A W Veldhuizen
- Department of Physiology & Pharmacology, Western University, London, Ontario, Canada.,Department of Medicine, Western University, London, Ontario, Canada
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manon, Honolulu, Hawaii, USA.,Department of Pediatrics, University of Hawaii, Honolulu, Hawaii, USA
| | - Nils O Petersen
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Chemistry, Western University, London, Ontario, Canada
| | - James F Lewis
- Department of Physiology & Pharmacology, Western University, London, Ontario, Canada.,Department of Medicine, Western University, London, Ontario, Canada
| | - Fred Possmayer
- Department of Biochemistry, Western University, London, Ontario, Canada.,Department of Obstetrics/Gynaecology, Western University, London, Ontario, Canada
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Yin C, Blom JN, Lewis JF. The 2nd Annual Clinical Scientist Trainee Symposium, August 22, 2017, London, Canada. CLIN INVEST MED 2018; 41:E34-E36. [PMID: 29603690 DOI: 10.25011/cim.v41i1.29462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Indexed: 11/03/2022]
Abstract
Clinician scientists play a critical role in bridging research and clinical practice. Unfortunately, the neglect of research training in medical schools has created clinicians who are unable to translate evidence from literature to practice. Furthermore, the erosion of research training in medical education has resulted in clinicians who lack the skills required for successful scientific investigation. To counteract this, the Schulich School of Medicine & Dentistry has made an effort to engage trainees, at all levels, in the research process. The 2nd Annual Clinician Scientist Trainee Symposium was held in London, Ontario, Canada on August 22, 2017. Organized each year since 2016 by the Schulich Research Office, the symposium features research being conducted by trainees in Schulich's Clinical Research Training Program. The focus this year was on the current state of clinician-scientist training in Canada and visions for the path ahead.
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Ford NL, McCaig L, Jeklin A, Lewis JF, Veldhuizen RAW, Holdsworth DW, Drangova M. A respiratory-gated micro-CT comparison of respiratory patterns in free-breathing and mechanically ventilated rats. Physiol Rep 2017; 5:5/2/e13074. [PMID: 28100723 PMCID: PMC5269405 DOI: 10.14814/phy2.13074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 11/14/2016] [Accepted: 11/19/2016] [Indexed: 11/24/2022] Open
Abstract
In this study, we aim to quantify the differences in lung metrics measured in free-breathing and mechanically ventilated rodents using respiratory-gated micro-computed tomography. Healthy male Sprague-Dawley rats were anesthetized with ketamine/xylazine and scanned with a retrospective respiratory gating protocol on a GE Locus Ultra micro-CT scanner. Each animal was scanned while free-breathing, then intubated and mechanically ventilated (MV) and rescanned with a standard ventilation protocol (56 bpm, 8 mL/kg and PEEP of 5 cm H2O) and again with a ventilation protocol that approximates the free-breathing parameters (88 bpm, 2.14 mL/kg and PEEP of 2.5 cm H2O). Images were reconstructed representing inspiration and end expiration with 0.15 mm voxel spacing. Image-based measurements of the lung lengths, airway diameters, lung volume, and air content were compared and used to calculate the functional residual capacity (FRC) and tidal volume. Images acquired during MV appeared darker in the airspaces and the airways appeared larger. Image-based measurements showed an increase in lung volume and air content during standard MV, for both respiratory phases, compared with matched MV and free-breathing. Comparisons of the functional metrics showed an increase in FRC for mechanically ventilated rats, but only the standard MV exhibited a significantly higher tidal volume than free-breathing or matched MV Although standard mechanical ventilation protocols may be useful in promoting consistent respiratory patterns, the amount of air in the lungs is higher than in free-breathing animals. Matching the respiratory patterns with the free-breathing case allowed similar lung morphology and physiology measurements while reducing the variability in the measurements.
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Affiliation(s)
- Nancy L Ford
- Department of Oral Biological and Medical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada .,Department of Physics and Astronomy, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Lynda McCaig
- Lawson Health Research Institute, London, Ontario, Canada
| | - Andrew Jeklin
- Department of Oral Biological and Medical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
| | - James F Lewis
- Lawson Health Research Institute, London, Ontario, Canada.,Departments of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Ruud A W Veldhuizen
- Lawson Health Research Institute, London, Ontario, Canada.,Departments of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - David W Holdsworth
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.,Medical Biophysics, University of Western Ontario, London, Ontario, Canada.,Medical Imaging, University of Western Ontario, London, Ontario, Canada
| | - Maria Drangova
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.,Medical Biophysics, University of Western Ontario, London, Ontario, Canada.,Medical Imaging, University of Western Ontario, London, Ontario, Canada
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Banaschewski BJH, Baer B, Arsenault C, Jazey T, Veldhuizen EJA, Delport J, Gooyers T, Lewis JF, Haagsman HP, Veldhuizen RAW, Yamashita C. The Antibacterial and Anti-inflammatory Activity of Chicken Cathelicidin-2 combined with Exogenous Surfactant for the Treatment of Cystic Fibrosis-Associated Pathogens. Sci Rep 2017; 7:15545. [PMID: 29138462 PMCID: PMC5686076 DOI: 10.1038/s41598-017-15558-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/30/2017] [Indexed: 01/12/2023] Open
Abstract
Cystic fibrosis (CF) is characterized by recurrent airway infections with antibiotic-resistant bacteria and chronic inflammation. Chicken cathelicin-2 (CATH-2) has been shown to exhibit antimicrobial activity against antibiotic-resistant bacteria and to reduce inflammation. In addition, exogenous pulmonary surfactant has been suggested to enhance pulmonary drug delivery. It was hypothesized that CATH-2 when combined with an exogenous surfactant delivery vehicle, bovine lipid extract surfactant (BLES), would exhibit antimicrobial activity against CF-derived bacteria and downregulate inflammation. Twelve strains of CF-pathogens were exposed to BLES+CATH-2 in vitro and killing curves were obtained to determine bactericidal activity. Secondly, heat-killed bacteria were administered in vivo to elicit a pro-inflammatory response with either a co-administration or delayed administration of BLES+CATH-2 to assess the antimicrobial-independent, anti-inflammatory properties of BLES+CATH-2. CATH-2 alone exhibited potent antimicrobial activity against all clinical strains of antibiotic-resistant bacteria, while BLES+CATH-2 demonstrated a reduction, but significant antimicrobial activity against bacterial isolates. Furthermore, BLES+CATH-2 reduced inflammation in vivo when either co-administered with killed bacteria or after delayed administration. The use of a host-defense peptide combined with an exogenous surfactant compound, BLES+CATH-2, is shown to exhibit antimicrobial activity against antibiotic-resistant CF bacterial isolates and reduce inflammation.
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Affiliation(s)
| | - Brandon Baer
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Christina Arsenault
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Teah Jazey
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Edwin J A Veldhuizen
- Department of Infectious Diseases and Immunology, Division of Molecular Host Defense, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Johan Delport
- London Health Sciences Centre, London, Ontario, Canada
| | | | - James F Lewis
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.,Department of Medicine, Western University, London, Ontario, Canada
| | - Henk P Haagsman
- Department of Infectious Diseases and Immunology, Division of Molecular Host Defense, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Ruud A W Veldhuizen
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada.,Department of Medicine, Western University, London, Ontario, Canada
| | - Cory Yamashita
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada. .,Department of Medicine, Western University, London, Ontario, Canada.
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Nakajima D, Liu M, Ohsumi A, Kalaf R, Iskender I, Hsin M, Kanou T, Chen M, Baer B, Coutinho R, Maahs L, Behrens P, Azad S, Martinu T, Waddell TK, Lewis JF, Post M, Veldhuizen RA, Cypel M, Keshavjee S. Lung Lavage and Surfactant Replacement During Ex Vivo Lung Perfusion for Treatment of Gastric Acid Aspiration–Induced Donor Lung Injury. J Heart Lung Transplant 2017; 36:577-585. [DOI: 10.1016/j.healun.2016.11.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/25/2016] [Accepted: 11/23/2016] [Indexed: 10/20/2022] Open
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Skinnider MA, Squair JW, Twa DDW, Ji JX, Kuzyk A, Wang X, Steadman PE, Zaslavsky K, Dey AK, Eisenberg MJ, Gagné ÈR, HayGlass KT, Lewis JF, Margetts PJ, Underhill DA, Rosenblum ND, Raymond LA. Characteristics and outcomes of Canadian MD/PhD program graduates: a cross-sectional survey. CMAJ Open 2017; 5:E308-E314. [PMID: 28442493 PMCID: PMC5498176 DOI: 10.9778/cmajo.20160152] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Combined MD/PhD programs provide a structured path for physician-scientist training, but assessment of their success within Canada is limited by a lack of quantitative data. We collected outcomes data for graduates of Canadian MD/PhD programs. METHODS We developed and implemented a Web-based survey consisting of 41 questions designed to collect outcomes data for Canadian MD/PhD program alumni from 8 Canadian universities who had graduated before September 2015. Respondents were categorized into 2 groups according to whether they had or had not completed all training. RESULTS Of the 186 eligible alumni of MD/PhD programs, 139 (74.7%) completed the survey. A total of 136/138 respondents (98.6%) had completed or were currently completing residency training, and 66/80 (82%) had completed at least 1 postgraduate fellowship. Most (58 [83%]) of the 70 respondents who had completed all training were appointed as faculty at academic institutions, and 37 (53%) had been principal investigators on at least 1 recent funded project. Among the 58 respondents appointed at academic institutions, 44/57 (77%) dedicated at least 20% of their time to research, and 25/57 (44%) dedicated at least 50% to research. During their combined degree, 102/136 respondents (75.0%) published 3 or more first-author papers, and 133/136 (97.8%) matched with their first choice of specialty. The median length of physician-scientist training was 13.5 years. Most respondents graduated with debt despite having been supported by Canadian Institutes of Health Research MD/PhD studentships. INTERPRETATION Most Canadian MD/PhD program alumni pursued careers consistent with their physician-scientist training, which indicates that these programs are meeting their primary objective. Nevertheless, our findings highlight that a minority of these positions are research intensive; this finding warrants further study. Our data provide a baseline for future monitoring of the output of Canadian MD/PhD programs.
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Affiliation(s)
- Michael A Skinnider
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Jordan W Squair
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - David D W Twa
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Jennifer X Ji
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Alexandra Kuzyk
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Xin Wang
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Patrick E Steadman
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Kirill Zaslavsky
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Ayan K Dey
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Mark J Eisenberg
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Ève-Reine Gagné
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Kent T HayGlass
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - James F Lewis
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Peter J Margetts
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - D Alan Underhill
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Norman D Rosenblum
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
| | - Lynn A Raymond
- Affiliations: Faculty of Medicine (Skinnider, Squair, Twa, Ji, Raymond), University of British Columbia, Vancouver, BC; Clinician-Investigator Training Association of Canada(Kuzyk, Wang, Steadman, Zaslavsky, Dey); Faculty of Health Sciences (Kuzyk, HayGlass), University of Manitoba, Winnipeg, Man.; Faculty of Medicine (Wang, Steadman, Zaslavsky, Dey, Rosenblum), University of Toronto, Toronto, Ont.; Faculty of Medicine (Eisenberg), McGill University, Montréal, Que.; Faculty of Medicine (Gagné), Université de Sherbrooke, Sherbrooke, Que.; Faculty of Medicine (Lewis), Western University, London, Ont.; Faculty of Medicine (Margetts), McMaster University, Hamilton, Ont.; Faculty of Medicine (Underhill), University of Alberta, Edmonton, Alta.; Canadian Society for Clinical Investigation (Underhill), Ottawa, Ont
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Puntorieri V, McCaig LA, Howlett CJ, Yao LJ, Lewis JF, Yamashita CM, Veldhuizen RAW. Lack of matrix metalloproteinase 3 in mouse models of lung injury ameliorates the pulmonary inflammatory response in female but not in male mice. Exp Lung Res 2016; 42:365-379. [PMID: 27676418 DOI: 10.1080/01902148.2016.1231243] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND The acute respiratory distress syndrome (ARDS) is a complex pulmonary disorder in which the local release of cytokines and chemokines appears central to the pathophysiology. OBJECTIVE Based on the known role of matrix metalloproteinase-3 (MMP3) in inflammatory processes, the objective was to examine the role of MMP3 in the pathogenesis of ARDS through the modulation of pulmonary inflammation. MATERIALS AND METHODS Female and male, wild type (MMP3+/+) and knock out (MMP3-/-) mice were exposed to two, clinically relevant models of ARDS including (i) lipopolysaccharide (LPS)-induced lung injury, and (ii) hydrochloric acid-induced lung injury. Parameters of lung injury and inflammation were assessed through measurements in lung lavage including total protein content, inflammatory cell influx, and concentrations of mediators such as TNF-α, IL-6, G-CSF, CXCL1, CXCL2, and CCL2. Lung histology and compliance were also evaluated in the LPS model of injury. RESULTS Following intra-tracheal LPS instillation, all mice developed lung injury, as measured by an increase in lavage neutrophils, and decrease in lung compliance, with no overall effect of genotype observed. Increased concentrations of lavage inflammatory cytokines and chemokines were also observed following LPS injury, however, LPS-instilled female MMP3-/- mice had lower levels of inflammatory mediators compared to LPS-instilled female MMP3+/+ mice. This effect of the genotype was not observed in male mice. Similar findings, including the MMP3-related sex differences, were also observed after acid-induced lung injury. CONCLUSION MMP3 contributes to the pathogenesis of ARDS, by affecting the pulmonary inflammatory response in female mice in relevant models of lung injury.
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Affiliation(s)
- Valeria Puntorieri
- a Department of Physiology and Pharmacology , Lawson Health Research Institute, Western University , London , Ontario , Canada
| | - Lynda A McCaig
- a Department of Physiology and Pharmacology , Lawson Health Research Institute, Western University , London , Ontario , Canada
| | - Christopher J Howlett
- b Department of Pathology and Laboratory Medicine , Western University , London , Ontario , Canada
| | - Li-Juan Yao
- c Department of Medicine , Western University , London , Ontario , Canada
| | - James F Lewis
- c Department of Medicine , Western University , London , Ontario , Canada
| | - Cory M Yamashita
- a Department of Physiology and Pharmacology , Lawson Health Research Institute, Western University , London , Ontario , Canada.,c Department of Medicine , Western University , London , Ontario , Canada
| | - Ruud A W Veldhuizen
- a Department of Physiology and Pharmacology , Lawson Health Research Institute, Western University , London , Ontario , Canada.,c Department of Medicine , Western University , London , Ontario , Canada
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Abstract
Congenital lobar emphysema is mainly diagnosed in infants, although rare cases are reported in adults. A 20-yr-old female with acute dyspnea, chest pain and left upper lobe (LUL) chest x-ray hyperlucency underwent 3He magnetic resonance imaging (MRI) for ventilation and apparent diffusion coefficient (ADC) measurements, as well as CT for emphysema and airway wall measurements. Forced expiratory volume in 1s, residual volume, and airways-resistance were abnormal, but there was normal carbon-monoxide-diffusing-capacity. The LUL relative area of the density histogram <-950 HU and airway morphology were highly abnormal compared with the other lobes and coincident with highly abnormal MRI-derived acinar duct dimensions. CT also identified bronchial atresia and congenital lobar emphysema as the source of symptoms in this case where there was also functional imaging evidence of collateral ventilation from the fissure (and not the abnormally terminated airway) into the emphysematous LUL.
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Affiliation(s)
- Damien Pike
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Canada ; Department of Medical Biophysics, The University of Western Ontario, London, Canada
| | - Sindu Mohan
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Canada ; Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada
| | - Weijing Ma
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Canada
| | - James F Lewis
- Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada
| | - Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute, The University of Western Ontario, London, Canada ; Department of Medical Biophysics, The University of Western Ontario, London, Canada ; Department of Medical Imaging, The University of Western Ontario, London, Canada
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9
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Hiansen JQ, Keating E, Aspros A, Yao LJ, Bosma KJ, Yamashita CM, Lewis JF, Veldhuizen RAW. Cholesterol-mediated surfactant dysfunction is mitigated by surfactant protein A. Biochim Biophys Acta 2014; 1848:813-20. [PMID: 25522687 DOI: 10.1016/j.bbamem.2014.12.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 12/05/2014] [Accepted: 12/09/2014] [Indexed: 01/12/2023]
Abstract
The ability of pulmonary surfactant to reduce surface tension at the alveolar surface is impaired in various lung diseases. Recent animal studies indicate that elevated levels of cholesterol within surfactant may contribute to its inhibition. It was hypothesized that elevated cholesterol levels within surfactant inhibit human surfactant biophysical function and that these effects can be reversed by surfactant protein A (SP-A). The initial experiment examined the function of surfactant from mechanically ventilated trauma patients in the presence and absence of a cholesterol sequestering agent, methyl-β-cyclodextrin. The results demonstrated improved surface activity when cholesterol was sequestered in vitro using a captive bubble surfactometer (CBS). These results were explored further by reconstitution of surfactant with various concentrations of cholesterol with and without SP-A, and testing of the functionality of these samples in vitro with the CBS and in vivo using surfactant depleted rats. Overall, the results consistently demonstrated that surfactant function was inhibited by levels of cholesterol of 10% (w/w phospholipid) but this inhibition was mitigated by the presence of SP-A. It is concluded that cholesterol-induced surfactant inhibition can actively contribute to physiological impairment of the lungs in mechanically ventilated patients and that SP-A levels may be important to maintain surfactant function in the presence of high cholesterol within surfactant.
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Affiliation(s)
- Joshua Qua Hiansen
- Department of Physiology & Pharmacology, The University of Western Ontario, London, Ontario, Canada.
| | | | - Alex Aspros
- Department of Physiology & Pharmacology, The University of Western Ontario, London, Ontario, Canada.
| | - Li-Juan Yao
- Lawson Health Research Institute, London, Ontario, Canada.
| | - Karen J Bosma
- Department of Medicine, The University of Western Ontario, London, Ontario, Canada.
| | - Cory M Yamashita
- Department of Physiology & Pharmacology, The University of Western Ontario, London, Ontario, Canada; Department of Medicine, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
| | - James F Lewis
- Department of Physiology & Pharmacology, The University of Western Ontario, London, Ontario, Canada; Department of Medicine, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
| | - Ruud A W Veldhuizen
- Department of Physiology & Pharmacology, The University of Western Ontario, London, Ontario, Canada; Department of Medicine, The University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
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10
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Paulin GA, Svenningsen S, Jobse BN, Mohan S, Kirby M, Lewis JF, Parraga G. Differences in hyperpolarized (3) He ventilation imaging after 4 years in adults with cystic fibrosis. J Magn Reson Imaging 2014; 41:1701-7. [PMID: 25174316 DOI: 10.1002/jmri.24744] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/14/2014] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To evaluate cystic fibrosis (CF) subjects over 4 years using (3) He magnetic resonance imaging (MRI), pulmonary function tests, and track hospitalization and physician visits. MATERIALS AND METHODS Five CF adults provided written informed consent to an approved protocol and underwent MRI, spirometry, and plethysmography at baseline, 7 days, and 4 ± 1 years later. (3) He MRI ventilation defect percent (VDP) was generated for all subjects and timepoints. RESULTS After 4 years, mean forced expiratory volume in 1 second / forced vital capacity (FEV1 /FVC) was lower (P = 0.01) in all subjects and there were no other pulmonary function test changes. Two CF adults showed significantly elevated (worse) (3) He VDP at baseline and after 4 years they had significantly greater (worsened) VDP (P = 0.02), without a significant FEV1 decline (P = 0.06) but with a greater number of exacerbations (P < 0.05). Baseline VDP strongly correlated with FEV1 (r(2) = 0.98, P = 0.0007) at 4-year follow-up. CONCLUSION For two CF subjects, VDP was significantly worse at baseline and worsened over 4 years, which was in agreement with a greater number of hospitalizations and clinic visits. These results are limited by the very small sample size, but the strong VDP correlation with longitudinal changes in FEV1 generates the hypothesis that abnormal VDP may temporally precede FEV1 decline in CF subjects; this must be tested in a larger CF study.
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Affiliation(s)
- Gregory A Paulin
- Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - Sarah Svenningsen
- Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - Brian N Jobse
- Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada
| | - Sindu Mohan
- Division of Respirology Department of Medicine, University of Western Ontario, London, Canada
| | - Miranda Kirby
- Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada
| | - James F Lewis
- Division of Respirology Department of Medicine, University of Western Ontario, London, Canada
| | - Grace Parraga
- Imaging Research Laboratories, Robarts Research Institute, University of Western Ontario, London, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Canada.,Department of Medical Imaging, University of Western Ontario, London, Canada
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11
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Puntorieri V, Hiansen JQ, McCaig LA, Yao LJ, Veldhuizen RAW, Lewis JF. The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury. BMC Pulm Med 2013; 13:67. [PMID: 24256698 PMCID: PMC4222563 DOI: 10.1186/1471-2466-13-67] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 11/14/2013] [Indexed: 01/11/2023] Open
Abstract
Background Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Methods Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). Results For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. Conclusions The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.
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Affiliation(s)
- Valeria Puntorieri
- Department of Physiology & Pharmacology, Western University, London, Ontario, Canada.
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12
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Ford NL, McCaig LA, Lewis JF, Veldhuizen RA, Holdsworth DW, Drangova M. SU-C-218-04: Comparison of Respiratory Gated Micro-CT in Mechanically Ventilated and Free-Breathing Rats. Med Phys 2012. [DOI: 10.1118/1.4734652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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13
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Abstract
In 2007, Bosma et. al provided a comprehensive review of emerging therapies for the acute respiratory distress syndrome (ARDS), a condition which continues to carry a mortality rate of greater than 30%. Over the past several years, the development of novel and effective therapeutic agents for ARDS remains disappointing, and unfortunately, no recent therapeutic interventions have demonstrated a clear benefit. Herein, the results of several of these early and late phase clinical trials are reviewed, the majority of which address known maladaptive processes that have been deemed critical in ARDS pathophysiology. Based on the ongoing futility of current therapeutic models to yield effective therapies, it is speculated whether or not novel treatment paradigms, which address distinctly different aspects of this disease paradigm, may be warranted.
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14
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Abstract
Despite the use of lung-protective mechanical ventilation (MV), the mortality of patients with acute lung injury remains at 30 to 40%, predominantly due to multiorgan failure. The objective of this study was to determine the biological significance of lung-derived mediators on peripheral organ inflammation. The authors utilized an isolated perfused mouse lung model of lipopolysaccharide (LPS)-induced lung inflammation and protective MV to collect lung-derived mediators. Aliquots of perfusate from these animals (or appropriate controls) were then injected intravenously into a cohort of normal animals whose livers were subsequently assessed in vivo using intravital video microscopy. Perfusate from LPS-inflamed lungs contained significantly higher concentrations of inflammatory mediators than perfusate from saline-instilled lungs. Assessment of livers in the second cohort of animals 120 minutes after perfusate injection revealed decreased sinusoidal blood flow, leukocytosis, and increased cell death in those receiving perfusate from LPS-inflamed lungs compared to perfusate from saline controls. There were no differences between control animals that received pure perfusate or pure LPS mixed with perfusate. These results showed that lung-derived mediators had a significant biological effect on nonpulmonary organs within a short period of time after administration. Therapies targeting these mediators may prevent multiorgan failure and death in patients with acute lung injury.
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Affiliation(s)
- Nicole A Rocca
- Department of Physiology and Pharmacology and Lawson Health Research Institute, University of Western Ontario, London, Canada
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15
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Walker MG, Yao LJ, Patterson EK, Joseph MG, Cepinskas G, Veldhuizen RAW, Lewis JF, Yamashita CM. The effect of tidal volume on systemic inflammation in Acid-induced lung injury. ACTA ACUST UNITED AC 2011; 81:333-42. [PMID: 21311175 DOI: 10.1159/000323609] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 12/15/2010] [Indexed: 11/19/2022]
Abstract
BACKGROUND Overwhelming systemic inflammation has been implicated in the progression of acute lung injury (ALI) leading to multiple organ failure (MOF) and death. Previous studies suggest that mechanical ventilation (MV) may be a key mediator of MOF through an upregulation of the systemic inflammatory response. OBJECTIVES It was the aim of this study to investigate mechanisms whereby mechanical stress induced by different tidal volumes may contribute to the development of systemic inflammation and maladaptive peripheral organ responses in the setting of ALI. METHODS An acid aspiration model of ALI was employed in 129X1/SVJ mice through an intratracheal administration of hydrochloric acid followed by MV employing either a low (5 ml/kg) or high (12.5 ml/kg) tidal volume ventilation for 120 min. The isolated perfused mouse lung setup was used to assess the specific contribution of the lung to systemic inflammation during MV. Furthermore, lung perfusate collected over the course of MV was used to assess the effects of lung-derived mediators on activation (expression of a proadhesive phenotype) of liver endothelial cells. RESULTS High tidal volume MV of acid-injured lungs resulted in greater physiologic and histological indices of lung injury compared to control groups. Additionally, there was an immediate and significant release of multiple inflammatory mediators from the lung into the systemic circulation which resulted in greater levels of mRNA adhesion molecule expression in liver endothelial cells in vitro. CONCLUSIONS This study suggests that MV, specifically tidal volume strategy, influences the development of MOF through an upregulation of lung-derived systemic inflammation resulting in maladaptive cellular changes in peripheral organs.
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16
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Spragg RG, Taut FJH, Lewis JF, Schenk P, Ruppert C, Dean N, Krell K, Karabinis A, Günther A. Recombinant surfactant protein C-based surfactant for patients with severe direct lung injury. Am J Respir Crit Care Med 2010; 183:1055-61. [PMID: 21148720 DOI: 10.1164/rccm.201009-1424oc] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
RATIONALE Patients with acute lung injury have impaired function of the lung surfactant system. Prior clinical trials have shown that treatment with exogenous recombinant surfactant protein C (rSP-C)-based surfactant results in improvement in blood oxygenation and have suggested that treatment of patients with severe direct lung injury may decrease mortality. OBJECTIVES Determine the clinical benefit of administering an rSP-C-based synthetic surfactant to patients with severe direct lung injury due to pneumonia or aspiration. METHODS A prospective randomized blinded study was performed at 161 centers in 22 countries. Patients were randomly allocated to receive usual care plus up to eight doses of rSP-C surfactant administered over 96 hours (n = 419) or only usual care (n = 424). MEASUREMENTS AND MAIN RESULTS Mortality to 28 days after treatment, the requirement for mechanical ventilation, and the number of nonpulmonary organ failure-free days were not different between study groups. In contrast to prior studies, there was no improvement in oxygenation in patients receiving surfactant compared with the usual care group. Investigation of the possible reasons underlying the lack of efficacy suggested a partial inactivation of rSP-C surfactant caused by a step of the resuspension process that was introduced with this study. CONCLUSIONS In this study, rSP-C-based surfactant was of no clinical benefit to patients with severe direct lung injury. The unexpected lack of improvement in oxygenation, coupled with the results of in vitro tests, suggest that the administered suspension may have had insufficient surface activity to achieve clinical benefit.
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Affiliation(s)
- Roger G Spragg
- Veterans Affairs Medical Center, 3350 La Jolla Village Drive, San Diego, CA 92161, USA.
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17
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Truscott EA, McCaig LA, Yao LJ, Veldhuizen RAW, Lewis JF. Surfactant protein-A reduces translocation of mediators from the lung into the circulation. Exp Lung Res 2010; 36:431-9. [PMID: 20715984 DOI: 10.3109/01902141003721440] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The objective of this study was to characterize a mouse model of lung inflammation and determine the effect of surfactant protein A (SP-A, or sftpa) on the transfer of inflammatory mediators from these injured lungs into the systemic circulation. Lung inflammation was induced in either sftpa-deficient (-/-) or wild-type (+/+) spontaneously breathing, adult mice via intranasal lipopolysaccharide (LPS). Four hours later, lungs were isolated, perfused, and mechanically ventilated for 2 hours. Perfusate was collected for analysis over the duration of ventilation and lung lavage was obtained in groups of animals immediately before and after mechanical ventilation (MV). Lavage analysis showed an increase in interleukin-6 (IL6) and tumor necrosis factor-alpha (TNFalpha) 4 hours after LPS, with a further increase in IL6 following MV. LPS and MV also caused an increase in total cell and neutrophil numbers as well as total protein in the lavage compared to controls. Perfusate analysis revealed a significant increase in IL6 and TNFalpha after LPS and MV, with significantly greater levels of these mediators in sftpa (-/-) versus (+/+) mice. The authors conclude that LPS followed by MV resulted in lung inflammation and injury, and that SP-A significantly influenced inflammatory mediator release from these inflamed lungs into the perfusate.
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Affiliation(s)
- Emily A Truscott
- Department of Physiology and Pharmacology, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
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18
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Abstract
The acute respiratory distress syndrome (ARDS) arises from direct and indirect injury to the lungs and results in a life-threatening form of respiratory failure in a heterogeneous, critically ill patient population. Critical care technologies used to support patients with ARDS, including strategies for mechanical ventilation, have resulted in improved outcomes in the last decade. However, there is still a need for effective pharmacotherapies to treat ARDS, as mortality rates remain high. To date, no single pharmacotherapy has proven effective in decreasing mortality in adult patients with ARDS, although exogenous surfactant replacement has been shown to reduce mortality in the paediatric population with ARDS from direct causes. Several promising therapies are currently being investigated in preclinical and clinical trials for treatment of ARDS in its acute and subacute, exudative phases. These include exogenous surfactant therapy, β2-adrenergic receptor agonists, antioxidants, immunomodulating agents and HMG-CoA reductase inhibitors (statins). Recent research has also focused on prevention of acute lung injury and acute respiratory distress in patients at risk. Drugs such as captopril, rosiglitazone and incyclinide (COL-3), a tetracycline derivative, have shown promising results in animal models, but have not yet been tested clinically. Further research is needed to discover therapies to treat ARDS in its late, fibroproliferative phase. Given the vast number of negative clinical trials to date, it is unlikely that a single pharmacotherapy will effectively treat all patients with ARDS from differing causes. Future randomized controlled trials should target specific, more homogeneous subgroups of patients for single or combination therapy.
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Affiliation(s)
- Karen J Bosma
- Department of Medicine, Division of Respirology, The University of Western Ontario, London, Ontario, Canada.
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19
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Aspros AJ, Coto CG, Lewis JF, Veldhuizen RA. High-frequency oscillation and surfactant treatment in an acid aspiration model. Can J Physiol Pharmacol 2010; 88:14-20. [DOI: 10.1139/y09-096] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both exogenous surfactant therapy and high-frequency oscillation (HFO) have been proposed as clinical interventions in acute respiratory distress syndrome (ARDS). The combination of these 2 interventions has not been studied in a relevant model of ARDS. It was hypothesized that surfactant treatment combined with HFO is superior to either surfactant treatment or HFO alone in a model of ARDS. Adult rats had lung injury induced by instillation of 0.1 mol/L HCl, followed by randomization to one of 4 groups: Conventional mechanical ventilation (CMV) + air (no treatment), CMV + surfactant, HFO + air, and HFO + surfactant. Oxygenation, lung compliance, surfactant, and cytokine concentrations in the lung lavage were analyzed. The results showed superior oxygenation in HFO ventilated animals regardless of surfactant treatment compared with CMV. Nonsurfactant-treated animals ventilated with HFO had a significantly greater proportion of large aggregates, and had greater lung compliance compared with non-surfactant-treated animals ventilated with CMV. Surfactant therapy combined with HFO provided no advantages with respect to these outcomes. These data suggest an advantage of HFO over CMV when exogenous surfactant was not given, and that surfactant treatment combined with HFO was not superior to HFO ventilation alone.
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Affiliation(s)
- Alexander J. Aspros
- Lawson Health Research Institute, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Medicine, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
| | - Claudia G. Coto
- Lawson Health Research Institute, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Medicine, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
| | - James F. Lewis
- Lawson Health Research Institute, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Medicine, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
| | - Ruud A.W. Veldhuizen
- Lawson Health Research Institute, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Medicine, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4V2, Canada
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20
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Vockeroth D, Gunasekara L, Amrein M, Possmayer F, Lewis JF, Veldhuizen RAW. Role of cholesterol in the biophysical dysfunction of surfactant in ventilator-induced lung injury. Am J Physiol Lung Cell Mol Physiol 2010; 298:L117-25. [DOI: 10.1152/ajplung.00218.2009] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mechanical ventilation may lead to an impairment of the endogenous surfactant system, which is one of the mechanisms by which this intervention contributes to the progression of acute lung injury. The most extensively studied mechanism of surfactant dysfunction is serum protein inhibition. However, recent studies indicate that hydrophobic components of surfactant may also contribute. It was hypothesized that elevated levels of cholesterol significantly contribute to surfactant dysfunction in ventilation-induced lung injury. Sprague-Dawley rats ( n = 30) were randomized to either high-tidal volume or low-tidal volume ventilation and monitored for 2 h. Subsequently, the lungs were lavaged, surfactant was isolated, and the biophysical properties of this isolated surfactant were analyzed on a captive bubble surfactometer with and without the removal of cholesterol using methyl-β-cyclodextrin. The results showed lower oxygenation values in the high-tidal volume group during the last 30 min of ventilation compared with the low-tidal volume group. Surfactant obtained from the high-tidal volume animals had a significant impairment in function compared with material from the low-tidal volume group. Removal of cholesterol from the high-tidal volume group improved the ability of the surfactant to reduce the surface tension to low values. Subsequent reconstitution of high-cholesterol values led to an impairment in surface activity. It is concluded that increased levels of cholesterol associated with endogenous surfactant represent a major contributor to the inhibition of surfactant function in ventilation-induced lung injury.
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Affiliation(s)
| | - Lasantha Gunasekara
- Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Matthias Amrein
- Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Fred Possmayer
- Obstetrics and Gynecology, and
- Lawson Health Research Institute, University of Western Ontario, London, Ontario; and
| | - James F. Lewis
- Departments of 1Physiology and Pharmacology,
- Medicine, and
- Lawson Health Research Institute, University of Western Ontario, London, Ontario; and
| | - Ruud A. W. Veldhuizen
- Departments of 1Physiology and Pharmacology,
- Medicine, and
- Lawson Health Research Institute, University of Western Ontario, London, Ontario; and
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21
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Markovic N, McCaig LA, Stephen J, Mizuguchi S, Veldhuizen RAW, Lewis JF, Cepinskas G. Mediators released from LPS-challenged lungs induce inflammatory responses in liver vascular endothelial cells and neutrophilic leukocytes. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1066-76. [PMID: 19815624 DOI: 10.1152/ajpgi.00278.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The systemic inflammatory response plays an important role in the progression of acute lung injury (ALI) to multiple organ dysfunction syndrome (MODS). However, the role of lung-derived inflammatory mediators in induction of the inflammatory response in remote organs is poorly understood. To address the above, we investigated the effects of lung inflammation on induction of inflammatory response(s) in the liver in vitro. Inflammation in mouse lungs was induced by intranasal administration of lipopolysaccharide (LPS; 1 mg/ml) followed by mechanical ventilation using the isolated perfused mouse lung method to obtain and characterize lung perfusate from the pulmonary circulation. LPS administration to mouse lungs resulted in an increased release of inflammation-relevant cytokines and chemokines into the perfusate (Luminex assay) compared with the saline-controls. Subsequently, primary mouse liver vascular endothelial cells (LVEC) or mouse polymorphonuclear leukocytes (PMN) in vitro were stimulated with the perfusate obtained from saline- or LPS-challenged lungs and assessed for various inflammation-relevant end points. The obtained results indicate that stimulation of LVEC with perfusate obtained from LPS-challenged lungs results in 1) reactive oxygen species (ROS) production; 2) activation of NF-kappaB; and 3) expression of E-selectin, ICAM-1, and VCAM-1 and a subsequent increase in PMN rolling and adhesion to LVEC. In addition, perfusate from LPS-challenged lung induced activation of PMN with respect to increased ROS production and upregulation of cell surface levels of adhesion molecules MAC-1 and VLA-4. Heat-inactivation of the perfusate obtained from LPS-challenged lungs was very effective in suppressing increased proadhesive phenotype (i.e., E-selectin and ICAM-1 expression) in LVEC, whereas targeted inhibition (immunoneutralization) of TNF-alpha and/or IL-6 in LPS-lung perfusate had no effect. Taken together, these findings indicate that multiple proinflammatory mediators (proteinaceous in nature) released from inflamed lungs act synergistically to induce systemic activation of circulating PMN and promote inflammatory responses in liver vascular endothelial cells.
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Affiliation(s)
- N Markovic
- Centre for Critical Illness Research, Lawson Health Research Institute, London, ON, Canada
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22
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Walker MG, Tessolini JM, McCaig L, Yao LJ, Lewis JF, Veldhuizen RA. ELEVATED ENDOGENOUS SURFACTANT REDUCES INFLAMMATION IN AN ACUTE LUNG INJURY MODEL. Exp Lung Res 2009; 35:591-604. [DOI: 10.1080/01902140902780460] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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23
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Pace PW, Yao LJ, Wilson JX, Possmayer F, Veldhuizen RA, Lewis JF. THE EFFECTS OF HYPEROXIA EXPOSURE ON LUNG FUNCTION AND PULMONARY SURFACTANT IN A RAT MODEL OF ACUTE LUNG INJURY. Exp Lung Res 2009; 35:380-98. [DOI: 10.1080/01902140902745166] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
The current study determined if interleukin-6 (IL-6) had a causative role in the lung dysfunction and/or surfactant alterations associated with three different lung insults. IL-6 (or saline) was instilled into rats followed by mechanical ventilation in vivo for 4 hours. Also, IL-6 (-/-) and wild-type mice were subjected to 3 insults: ex vivo injurious mechanical ventilation; cecal ligation and perforation; and hyperoxia exposure. In all experiments, the presence or absence of IL-6 did not significantly influence gas exchange, lung compliance, or various surfactant measurements. These results suggest that IL-6 may have a limited role in the surfactant alterations observed in acute lung injury.
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Affiliation(s)
- Tomoo Nakamura
- Department of Perinatal Medicine and Maternal Care, National Center for Children Health and Development, Tokyo, Japan
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Martin EL, Truscott EA, Bailey TC, Leco KJ, McCaig LA, Lewis JF, Veldhuizen RAW. LUNG MECHANICS IN THE TIMP3 NULL MOUSE AND ITS RESPONSE TO MECHANICAL VENTILATION. Exp Lung Res 2009; 33:99-113. [PMID: 17454105 DOI: 10.1080/01902140701198625] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [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: 10/23/2022]
Abstract
Tissue inhibitor of metalloproteinase-3 (TIMP3) null mice develop emphysema-like airspace enlargement due to an enzymatic imbalance. This study investigates how these abnormalities alter lung mechanics and the response to 2 different mechanical ventilation strategies. Phenotypically, TIMP3 null mice had increased compliance, and decreased resistance, tissue damping, and tissue elastance over wild-type controls. Decreased compliance and increased resistance were observed following the injurious ventilation strategy; however, the TIMP3 null response to both ventilation strategies was similar to wild-type mice. In conclusion, TIMP3 null mice have significant alterations in lung mechanics; however, this does not affect their response to ventilation.
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Affiliation(s)
- Erica L Martin
- Department of Physiology and Pharmacology, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
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Markovic N, McCaig LA, Veldhuizen RAW, Lewis JF, Cepinskas G. Mediators Released from LPS‐challenged Lungs into Circulation Induce the Inflammatory Response in Liver Vascular Endothelial Cells. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.741.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nevena Markovic
- Centre for Critical Illness ResearchLawson Health Research InstituteLondonONCanada
- Physiology and Pharmacology
| | - Lynda A McCaig
- Centre for Critical Illness ResearchLawson Health Research InstituteLondonONCanada
| | - Ruud AW Veldhuizen
- Centre for Critical Illness ResearchLawson Health Research InstituteLondonONCanada
- Physiology and Pharmacology
| | - James F Lewis
- Centre for Critical Illness ResearchLawson Health Research InstituteLondonONCanada
- Physiology and Pharmacology
| | - Gediminas Cepinskas
- Centre for Critical Illness ResearchLawson Health Research InstituteLondonONCanada
- BiophysicsUniversity of Western OntarioLondonONCanada
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Ford NL, Martin EL, Lewis JF, Veldhuizen RAW, Holdsworth DW, Drangova M. Quantifying lung morphology with respiratory-gated micro-CT in a murine model of emphysema. Phys Med Biol 2009; 54:2121-30. [DOI: 10.1088/0031-9155/54/7/018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
BACKGROUND Dobutamine stress echocardiography (DSE) is commonly used for diagnosis and management of patients with known or suspected coronary artery disease. Chest pain occurring during DSE potentially provides additional diagnostic accuracy. Our experience suggests that chest pain occurs frequently in women undergoing DSE. HYPOTHESIS It was the purpose of this study to determine the frequency with which chest pain occurs in women undergoing DSE and the relation to inducible ischemia or coronary artery stenosis. METHODS To determine the prevalence and clinical significance or chest pain during DSE, we reviewed the records of 154 consecutive women undergoing DSE in our laboratory. Of these, 59 patients (37.5%) also underwent coronary angiography. The presence or absence of chest pain was correlated with ECG changes, left ventricular wall motion abnormalities during DSE, and coronary stenosis by angiography. RESULTS Forty-one women (26%) developed chest pain during DSE. Patients experiencing chest pain were older (58.5 +/- 9.3 vs. 54.9 +/- 12.6; p = 0.05), and had lower resting heart rates (71 +/- 12.2 vs. 77.9 +/- 14.9; p = 0.008), but received similar maximum doses of dobutamine and reached comparable peak heart rates (131.1 +/- 17.4 vs. 133.5 +/- 21.7; p = NS). Patients with chest pain more commonly exhibited ST-segment depression > or = 1 mm during dobutamine infusion (13/41, 32%, vs. 17/113, 15%; p = 0.02), but chest pain showed no statistically significant correlation with abnormal DSE or with coronary stenosis. CONCLUSIONS In women undergoing DSE, chest pain occurs in 26% and does not appear to be related to inducible myocardial ischemia. Electrocardiographic changes occur more frequently in patients who experience chest pain, but are also often unrelated to inducible myocardial ischemia.
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Affiliation(s)
- C Sizemore
- Department of Medicine, University of Florida, Gainesville, USA
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Abstract
Intracardiac masses are often diagnosed by transthoracic echocardiography (TTE). Transesophageal echocardiography (TEE) improves overall visualization of masses, especially those located in the posterior cardiac structures. Masses in the heart are most commonly due to thrombi or valvular vegetations; however, a variety of tumors may also present as cardiac masses on echocardiography. Tumors of the heart most commonly occur in the setting of metastatic disease, usually from malignancies of the breast, lung, or from malignant melanoma. Primary cardiac tumors occur much less frequently and are usually benign. Atrial myxomas constitute nearly one-half of reported primary cardiac tumors. The following discussion details the findings of five cases that illustrate the spectrum of intracardiac tumors detected by echocardiography and reviews the relevant literature.
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Affiliation(s)
- A Lobo
- Department of Internal Medicine, University of Florida College of Medicine, Gainesville, USA
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Lewis JF. Classic echocardiographic features of hypertrophic cardiomyopathy. Clin Cardiol 2009; 21:127. [PMID: 9491953 PMCID: PMC6656083 DOI: 10.1002/clc.4960210212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Abstract
BACKGROUND Conventional approaches to management of congestive heart failure (CHF) rely on drugs that increase myocardial contractility or reduce ventricular afterload. These approaches often improve cardiac symptoms and survival, but may be associated with significant deleterious effects. An alternative approach is to enhance myocardial energy production. Dichloroacetate (DCA) stimulates pyruvate dehydrogenase activity and accelerates aerobic glucose, pyruvate, and lactate metabolism in myocardial cells. These alterations would be expected to improve myocardial function. HYPOTHESIS The purpose of the investigation was to assess the efficacy of DCA in patients with left ventricular systolic dysfunction and to examine the mechanism by which improvement occurs. METHODS A total of 25 patients (16 men, 9 women; age range 31-72 years, mean 59) with CHF and ejection fraction < or = 40% received an intravenous infusion of 50 mg/kg DCA over 15 min. Indices of systolic and diastolic function were obtained by two-dimensional and Doppler echocardiography performed at baseline, 30 min, and 60 min following completion of DCA infusion. RESULTS Baseline ventricular ejection fraction was 27.3 +/- 9.1%; 17 patients (68%) had nonischemic cardiomyopathy. Heart rate increased after DCA infusion from 73.9 +/- 14.5 to 79.2 +/- 14.9 beats/min at 60 min; p = 0.02. Left ventricular diastolic and systolic volumes increased at 30 min compared with baseline (248.7 +/- 98.1 vs. 259.6 +/- 99.6; p = 0.04, and 180.1 +/- 80.4 vs. 192.2 +/- 84.9; p = 0.002, respectively), but stroke volume (49.2 +/- 19.1 vs. 48.9 +/- 18.1; p = 0.9) and ejection fraction (27.3 +/- 9.1 vs. 25.7 +/- 9.8; p = 0.2) were unchanged. Indices of diastolic function were also unchanged. CONCLUSION Dichloroacetate infusion in patients with CHF is not associated with improvement in noninvasively assessed left ventricular function.
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Affiliation(s)
- J F Lewis
- Department of Medicine, University of Florida College of Medicine, Gainesville, USA
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Abstract
Stress echocardiography is a widely applied technique for the evaluation of individuals with known or suspected coronary artery disease. The technique combines echocardiographic imaging with exercise testing or pharmacologic stress. Advances in digital image acquisition and harmonic imaging have substantially improved the quality of echocardiographic images, and have therefore increased general applicability of stress echocardiography.
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Affiliation(s)
- J F Lewis
- Department of Internal Medicine, University of Florida College of Medicine, Gainesville 32610-0277, USA
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Affiliation(s)
- T A Burkart
- Department of Medicine, University of Florida, Gainesville 32610-0277, USA
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Taut FJ, Rippin G, Schenk P, Findlay G, Wurst W, Häfner D, Lewis JF, Seeger W, Günther A, Spragg RG. A Search for Subgroups of Patients With ARDS Who May Benefit From Surfactant Replacement Therapy. Chest 2008; 134:724-732. [DOI: 10.1378/chest.08-0362] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Maruscak AA, Vockeroth DW, Girardi B, Sheikh T, Possmayer F, Lewis JF, Veldhuizen RAW. Alterations to surfactant precede physiological deterioration during high tidal volume ventilation. Am J Physiol Lung Cell Mol Physiol 2008; 294:L974-83. [DOI: 10.1152/ajplung.00528.2007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung injury due to mechanical ventilation is associated with an impairment of endogenous surfactant. It is unknown whether this impairment is a consequence of or an active contributor to the development and progression of lung injury. To investigate this issue, the present study addressed three questions: Do alterations to surfactant precede physiological lung dysfunction during mechanical ventilation? Which components are responsible for surfactant's biophysical dysfunction? Does exogenous surfactant supplementation offer a physiological benefit in ventilation-induced lung injury? Adult rats were exposed to either a low-stretch [tidal volume (Vt) = 8 ml/kg, positive end-expiratory pressure (PEEP) = 5 cmH2O, respiratory rate (RR) = 54–56 breaths/min (bpm), fractional inspired oxygen (FiO2) = 1.0] or high-stretch (Vt = 30 ml/kg, PEEP = 0 cmH2O, RR = 14–16 bpm, FiO2 = 1.0) ventilation strategy and monitored for either 1 or 2 h. Subsequently, animals were lavaged and the composition and function of surfactant was analyzed. Separate groups of animals received exogenous surfactant after 1 h of high-stretch ventilation and were monitored for an additional 2 h. High stretch induced a significant decrease in blood oxygenation after 2 h of ventilation. Alterations in surfactant pool sizes and activity were observed at 1 h of high-stretch ventilation and progressed over time. The functional impairment of surfactant appeared to be caused by alterations to the hydrophobic components of surfactant. Exogenous surfactant treatment after a period of high-stretch ventilation mitigated subsequent physiological lung dysfunction. Together, these results suggest that alterations of surfactant are a consequence of the ventilation strategy that impair the biophysical activity of this material and thereby contribute directly to lung dysfunction over time.
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Yamashita C, Forbes A, Tessolini JM, Yao LJ, Lewis JF, Veldhuizen RAW. Protective effects of elevated endogenous surfactant pools to injurious mechanical ventilation. Am J Physiol Lung Cell Mol Physiol 2008; 294:L724-32. [DOI: 10.1152/ajplung.00389.2007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Depletion of alveolar macrophages (AM) leads to an increase in endogenous surfactant that lasts several days beyond the repletion of AM. Furthermore, impairment to the endogenous pulmonary surfactant system contributes to ventilation-induced lung injury. The objective of the current study was to determine whether increased endogenous surfactant pools induced via AM depletion was protective against ventilation-induced lung injury. Adult rats were intratracheally instilled with either control or dichloromethylene diphosphonic acid (DMDP) containing liposomes to deplete AMs and thereby increase endogenous surfactant pools. Either 3 or 7 days following instillation, rats were exposed to 2 h of injurious ventilation using either an ex vivo or in vivo ventilation protocol and were compared with nonventilated controls. The measured outcomes were oxygenation, lung compliance, lavage protein, and inflammatory cytokine concentrations. Compared with controls, the DMDP-treated animals had significantly reduced AM numbers and increased surfactant pools 3 days after instillation. Seven days after instillation, AM numbers had returned to normal, but surfactant pools were still elevated. DMDP-treated animals at both time points exhibited protection against ventilation-induced lung injury, which included superior physiological parameters, lower protein leakage, and lower inflammatory mediator release into the air space, compared with animals not receiving DMDP. It is concluded that DMDP-liposome administration protects against ventilation-induced lung injury. This effect appears to be due to the presence of elevated endogenous surfactant pools.
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Aquilante CL, Yarandi HN, Cavallari LH, Andrisin TE, Terra SG, Lewis JF, Hamilton KK, Johnson JA. β-Adrenergic receptor gene polymorphisms and hemodynamic response to dobutamine during dobutamine stress echocardiography. Pharmacogenomics J 2008; 8:408-15. [DOI: 10.1038/sj.tpj.6500490] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a life-threatening form of respiratory failure that affects a heterogeneous population of critically ill patients. Although overall mortality appears to be decreasing in recent years due to improvements in supportive care, there are presently no proven, effective pharmacological therapies to treat ARDS and prevent its associated complications. The most common cause of death in ARDS is not hypoxemia or pulmonary failure, but rather multiple organ dysfunction syndrome (MODS), suggesting that improving survival in patients with ARDS may be linked to decreasing the incidence or severity of MODS. The key to developing novel treatments depends, in part, on identifying and understanding the mechanisms by which ARDS leads to MODS, although the heterogeneity and complexity of this disorder certainly poses a challenge to investigators. Novel therapies in development for treatment of ALI/ARDS include exogenous surfactant, therapies aimed at modulating neutrophil activity, such as prostaglandin and complement inhibitors, and treatments targeting earlier resolution of ARDS, such as beta-agonists and granulocyte macrophage colony-stimulating factor. From a clinical perspective, identifying subpopulations of patients most likely to benefit from a particular therapy and recognising the appropriate stage of illness in which to initiate treatment could potentially lead to better outcomes in the short term.
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Affiliation(s)
- Karen J Bosma
- University of Western Ontario, Division of Respirology, London Health Sciences Centre, University Hospital, 339 Windermere Road, London, Ontario, N6A 5A5, Canada.
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Martin EL, Sheikh TA, Leco KJ, Lewis JF, Veldhuizen RAW. Contribution of alveolar macrophages to the response of the TIMP-3 null lung during a septic insult. Am J Physiol Lung Cell Mol Physiol 2007; 293:L779-89. [PMID: 17586692 DOI: 10.1152/ajplung.00442.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [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: 11/22/2022] Open
Abstract
Mice deficient in tissue inhibitor of metalloproteinase-3 (TIMP-3) develop an emphysema-like phenotype involving increased pulmonary compliance, tissue degradation, and matrix metalloproteinase (MMP) activity. After a septic insult, they develop a further increase in compliance that is thought to be a result of heightened metalloproteinase activity produced by the alveolar macrophage, potentially modeling an emphysemic exacerbation. Therefore, we hypothesized that TIMP-3 null mice lacking alveolar macrophages would not be susceptible to the altered lung function associated with a septic insult. TIMP-3 null and wild-type (WT) mice were depleted of alveolar macrophages before the induction of a septic insult and assessed for alteration in lung mechanics, alveolar structure, metalloproteinase levels, and inflammation. The results showed that TIMP-3 null mice lacking alveolar macrophages were protected from sepsis-induced alterations in lung mechanics, particularly pulmonary compliance, a finding that was supported by changes in alveolar structure. Additionally, changes in lung mechanics involved primarily peripheral tissue vs. central airways as determined using the flexiVent system. From investigation into possible molecules that could cause these alterations, it was found that although several proteases and inflammatory mediators were increased during the septic response, only MMP-7 was attenuated after macrophage depletion. In conclusion, the alveolar macrophage is essential for the TIMP-3 null sepsis-induced compliance alterations. This response may be mediated in part by MMP-7 activity but occurs independently of inflammatory cytokine and/or chemokine concentrations.
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Affiliation(s)
- Erica L Martin
- Department of Physiology and Pharmacology, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
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40
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Ford NL, Martin EL, Lewis JF, Veldhuizen RAW, Drangova M, Holdsworth DW. In vivo characterization of lung morphology and function in anesthetized free-breathing mice using micro-computed tomography. J Appl Physiol (1985) 2007; 102:2046-55. [PMID: 17255374 DOI: 10.1152/japplphysiol.00629.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [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: 11/22/2022] Open
Abstract
Lung morphology and function in human subjects can be monitored with computed tomography (CT). Because many human respiratory diseases are routinely modeled in rodents, a means of monitoring the changes in the structure and function of the rodent lung is desired. High-resolution images of the rodent lung can be attained with specialized micro-CT equipment, which provides a means of monitoring rodent models of lung disease noninvasively with a clinically relevant method. Previous studies have shown respiratory-gated images of intubated and respirated mice. Although the image quality and resolution are sufficient in these studies to make quantitative measurements, these measurements of lung structure will depend on the settings of the ventilator and not on the respiratory mechanics of the individual animals. In addition, intubation and ventilation can have unnatural effects on the respiratory dynamics of the animal, because the airway pressure, tidal volume, and respiratory rate are selected by the operator. In these experiments, important information about the symptoms of the respiratory disease being studied may be missed because the respiration is forced to conform to the ventilator settings. In this study, we implement a method of respiratory-gated micro-CT for use with anesthetized free-breathing rodents. From the micro-CT images, quantitative analysis of the structure of the lungs of healthy unconscious mice was performed to obtain airway diameters, lung and airway volumes, and CT densities at end expiration and during inspiration. Because the animals were free breathing, we were able to calculate tidal volume (0.09 +/- 0.03 ml) and functional residual capacity (0.16 +/- 0.03 ml).
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Affiliation(s)
- N L Ford
- Robarts Research Institute, London, ON, Canada N6A5K8.
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Abstract
The importance of pulmonary surfactant in maintaining normal lung function, and the observations that alterations in endogenous surfactant contribute to the lung dysfunction associated with acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS), provide a rationale for administering exogenous surfactant in this setting. The results of clinical trials have been variable, however, in part due to the various surfactant preparations used, the different delivery and dosing methods employed, and the types of patients targeted for this therapy. Based on the insight gained from these studies, ongoing trials have modified these factors to optimize outcome, including one trial that is focusing on patients with direct lung insults such as pneumonia and aspiration. The future of surfactant therapy may well take advantage of the recently described host defense functions of this material. Based on extensive in vitro data as well as in vivo animal studies demonstrating the anti-inflammatory and antibacterial functions of various surfactant components, administration of surfactant earlier in the course of the disease, when lung inflammation is present but before severe lung dysfunction occurs, may prove to be optimal. This review discusses both the biophysical and host defense functions of surfactant in the context of novel therapeutic approaches for patients with ALI/ARDS.
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Affiliation(s)
- James F Lewis
- St. Joseph's Health Centre, University of Western Ontario, London, Ontario, Canada.
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Yamashita CM, Forbes AR, Veldhuizen R, Lewis JF. PROTECTIVE EFFECT OF ELEVATED ENDOGENOUS SURFACTANT POOLS IN RATS SUBJECTED TO INJURIOUS MECHANICAL VENTILATION. Chest 2006. [DOI: 10.1378/chest.130.4_meetingabstracts.208s-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Bailey TC, Maruscak AA, Petersen A, White S, Lewis JF, Veldhuizen RAW. Physiological effects of oxidized exogenous surfactant in vivo: effects of high tidal volume and surfactant protein A. Am J Physiol Lung Cell Mol Physiol 2006; 291:L703-9. [PMID: 16632516 DOI: 10.1152/ajplung.00538.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [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: 11/22/2022] Open
Abstract
Oxidative damage to surfactant can decrease lung function in vivo. In the current study, our two objectives were: 1) to examine whether the adverse effects of oxidized surfactant would be accentuated in animals exposed to high tidal volume ventilation, and 2) to test whether supplementation with surfactant protein A (SP-A) could improve the function of oxidized surfactant in vivo. The first objective was addressed by evaluating the response of surfactant-deficient rats administered normal or oxidized surfactant and then subjected to low tidal volume (6 ml/kg) or high tidal volume (12 ml/kg) mechanical ventilation. Under low tidal volume conditions, rats administered oxidized surfactant had impaired lung function, as determined by lung compliance and arterial blood gas analysis, compared with nonoxidized controls. Animals subjected to high tidal volume ventilation had impaired lung function compared with low tidal volume groups, regardless of the oxidative status of the surfactant. The second experiment demonstrated a significantly superior physiological response in surfactant-deficient rats receiving SP-A containing oxidized surfactant compared with oxidized surfactant. Lavage analysis at the end of the in vivo experimentation showed no differences in the recovery of oxidized surfactant compared with nonoxidized surfactant. We conclude that minimizing excessive lung stretch during mechanical ventilation is important in the context of exogenous surfactant supplementation and that SP-A has an important biophysical role in surfactant function in conditions of oxidative stress. Furthermore, the oxidative status of the surfactant does not appear to affect the alveolar metabolism of this material.
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Affiliation(s)
- Timothy C Bailey
- Lawson Health Research Institute, Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario N6A 4V2, Canada
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Abstract
Pulmonary surfactant is altered in sepsis, and these changes contribute to the predisposition of septic lungs to subsequent insults, ultimately leading to acute lung injury. Specifically, the total amount of surfactant is lower in sepsis, mainly due to decreased small aggregate (SA) surfactant pools. The amount of large aggregate (LA) surfactant is not altered. To evaluate the mechanisms responsible for these alterations, trace doses of tritium-labelled dipalmitoylphosphatidylcholine (3H-DPPC)-labelled LA were instilled intratracheally into adult rats 20 hrs after caecal ligation and perforation (CLP) or sham surgery. Animals were sacrificed at 0, 1 and 4 h after instillation and recovery of 3H-DPPC in alveolar macrophages (AM), LA and SA was measured. In separate in vitro experiments, AM isolated from CLP/sham rats were incubated with LA or SA isolated from normal animals to evaluate the uptake of these aggregates into the AM. Results showed increased surfactant radioactivity associated with AM of CLP animals compared with sham animals both in vivo and in vitro. In addition, more 3H-DPPC label remained in LA forms in the CLP animals in vivo compared with sham. These findings indicate that differences in surfactant aggregate uptake and large aggregate conversion occur in septic lungs, resulting in changes in surfactant pools.
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Affiliation(s)
- W Huang
- Dept of Physiology, Pharmacology and Medicine, Lawson Health Research Institute, University of Western Ontario, London, ON N6A 4V2, Canada
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Martin EL, McCaig LA, Moyer BZ, Pape MC, Leco KJ, Lewis JF, Veldhuizen RAW. Differential response of TIMP-3 null mice to the lung insults of sepsis, mechanical ventilation, and hyperoxia. Am J Physiol Lung Cell Mol Physiol 2005; 289:L244-51. [PMID: 15805139 DOI: 10.1152/ajplung.00070.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [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: 11/22/2022] Open
Abstract
An imbalance in matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) leads to excessive or insufficient tissue breakdown, which is associated with many disease processes. The TIMP-3 null mouse is a model of MMP/TIMP imbalance, which develops air space enlargement and decreased lung function. These mice responded differently to cecal ligation and perforation (CLP)-induced septic lung injury than wild-type controls. The current study addresses whether the TIMP-3 knockout lung is susceptible to different types of insults or only those involving sepsis, by examining its response to lipopolysaccharide (LPS)-induced sepsis, mechanical ventilation (MV), and hyperoxia. TIMP-3 null noninjured controls of each insult consistently demonstrated significantly higher compliance vs. wild-type mice. Null mice treated with LPS had a further significantly increased compliance compared with untreated controls. Conversely, MV and hyperoxia did not alter compliance in the null lung. MMP abundance and activity increased in response to LPS but were generally unaltered following MV or hyperoxia, correlating with compliance alterations. All three insults produced inflammatory cytokines; however, the response of the null vs. wild-type lung was dependent on the type of insult. Overall, this study demonstrated that 1) LPS-induced sepsis produced a similar response in null mice to CLP-induced sepsis, 2) the null lung responded differently to various insults, and 3) the null susceptibility to compliance changes correlated with increased MMPs. In conclusion, this study provides insight into the role of TIMP-3 in response to various lung insults, specifically its importance in regulating MMPs to maintain compliance during a sepsis.
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Affiliation(s)
- Erica L Martin
- Departments of Physiology and Pharmacology Lawson Health Research Inst. H417, 268 Grosvenor St., London, ON, Canada, N6A 4V2.
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Abstract
OBJECTIVE Pneumonia occurs in approximately 7% of hospitalized patients. Susceptibility to certain bacteria such as Pseudomonas aeruginosa increases in critically ill patients, particularly those requiring mechanical ventilation. Previous studies investigating this susceptibility have used injurious modes of ventilation. The objective of this study was to evaluate the host's response to intratracheal instillation of P. aeruginosa in the setting of noninjurious mechanical ventilation and compare this with normal, spontaneously breathing animals receiving bacteria. DESIGN Randomized, controlled in vivo animal study. SETTING Research laboratory at a university-affiliated institution. SUBJECTS Adult male Sprague-Dawley rats. INTERVENTIONS Rats were randomized into four groups: spontaneously breathing given saline, spontaneously breathing given bacteria, mechanically ventilated given saline, and mechanically ventilated given bacteria. The ventilation strategy used involved low stretch (tidal volume of 8 mL/kg) with a positive end-expiratory pressure of 5 cm H2O. MEASUREMENTS AND MAIN RESULTS Lung compliance, bacterial recovery, surfactant, total cells, and cytokine concentrations in the lung lavage were analyzed after 4 hrs. Results showed that neither ventilation nor bacteria alone altered lung function, although the combination of ventilation and Pseudomonas significantly decreased arterial oxygenation and lung compliance. Increases in lavage cell counts, cytokines, and surfactant were observed in both groups administered bacteria compared with animals given saline. However, there were no significant differences in bacterial recovery, cell counts, cytokines, and surfactant measurements in the groups given bacteria. CONCLUSIONS These data suggest that bacterial instillation with low-stretch ventilation had a significant effect on lung function but did not alter the inflammatory response to a bacterial challenge over this time course compared with spontaneously breathing animals.
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Affiliation(s)
- Angela M Brackenbury
- Department of Medicine, St. Joseph's Health Care Centre, London, Ontario, Canada
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Spragg RG, Lewis JF, Walmrath HD, Johannigman J, Bellingan G, Laterre PF, Witte MC, Richards GA, Rippin G, Rathgeb F, Häfner D, Taut FJH, Seeger W. Effect of recombinant surfactant protein C-based surfactant on the acute respiratory distress syndrome. N Engl J Med 2004; 351:884-92. [PMID: 15329426 DOI: 10.1056/nejmoa033181] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Preclinical studies suggest that exogenous surfactant may be of value in the treatment of the acute respiratory distress syndrome (ARDS), and two phase 2 clinical trials have shown a trend toward benefit. We conducted two phase 3 studies of a protein-containing surfactant in adults with ARDS. METHODS In two multicenter, randomized, double-blind trials involving 448 patients with ARDS from various causes, we compared standard therapy alone with standard therapy plus up to four intratracheal doses of a recombinant surfactant protein C-based surfactant given within a period of 24 hours. RESULTS The overall survival rate was 66 percent 28 days after treatment, and the median number of ventilator-free days was 0 (68 percent range, 0 to 26); there was no significant difference between the groups in terms of mortality or the need for mechanical ventilation. Patients receiving surfactant had a significantly greater improvement in blood oxygenation during the initial 24 hours of treatment than patients receiving standard therapy, according to both univariate and multivariate analyses. CONCLUSIONS The use of exogenous surfactant in a heterogeneous population of patients with ARDS did not improve survival. Patients who received surfactant had a greater improvement in gas exchange during the 24-hour treatment period than patients who received standard therapy alone, suggesting the potential benefit of a longer treatment course.
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Affiliation(s)
- Roger G Spragg
- University of California at San Diego, Veterans Affairs Medical Center, San Diego 92014, USA.
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Lewis JF, Veldhuizen RAW. Analyzing Surfactant Metabolism in Humans. Am J Respir Crit Care Med 2004; 170:2-3. [PMID: 15220117 DOI: 10.1164/rccm.2404012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
Surfactant research has progressed over the past several years to the extent that exogenous surfactant administration in patients with the acute respiratory distress syndrome (ARDS) is now being evaluated. Unfortunately, clinical responses have been variable, and we now need to take a look at how surfactant is altered in this disease so that more effective treatment strategies can be developed. This review briefly discusses the biophysical and host defense properties of surfactant, the impact of mechanical ventilation (MV) on the endogenous surfactant system and the most recent clinical data involving exogenous surfactant administration in patients with ARDS. Discussions regarding future directions of surfactant research both in ARDS and diseases other than acute lung injury are included.
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Affiliation(s)
- J F Lewis
- St Joseph's Health Center, London, Ontario.
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Bailey TC, Da Silva KA, Lewis JF, Rodriguez-Capote K, Possmayer F, Veldhuizen RAW. Physiological and inflammatory response to instillation of an oxidized surfactant in a rat model of surfactant deficiency. J Appl Physiol (1985) 2003; 96:1674-80. [PMID: 14698995 DOI: 10.1152/japplphysiol.01143.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [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: 11/22/2022] Open
Abstract
Pulmonary surfactant is a mixture of phospholipids ( approximately 90%) and surfactant-associated proteins (SPs) ( approximately 10%) that stabilize the lung by reducing the surface tension. One proposed mechanism by which surfactant is altered during acute lung injury is via direct oxidative damage to surfactant. In vitro studies have revealed that the surface activity of oxidized surfactant was impaired and that this effect could be overcome by adding SP-A. On the basis of this information, we hypothesized that animals receiving oxidized surfactant preparations would exhibit an inferior physiological and inflammatory response and that the addition of SP-A to the oxidized preparations would ameliorate this response. To test this hypothesis, mechanically ventilated, surfactant-deficient rats were administered either bovine lipid extract surfactant (BLES) or in vitro oxidized BLES of three doses: 10 mg/kg, 50 mg/kg, or 10 mg/kg + SP-A. When instilled with 10 mg/kg normal surfactant, the rats had a significantly superior arterial Po2 responses compared with the rats receiving oxidized surfactant. Interestingly, increasing the dose five times mitigated this physiological effect, and the addition of SP-A to the surfactant preparation had little impact on improving oxygenation. There were no differences in alveolar surfactant pools and the indexes of pulmonary inflammation between the 10 mg/kg dose groups, nor was there any differences observed between either of the groups supplemented with SP-A. However, there was significantly more surfactant and more inflammatory cytokines in the 50 mg/kg oxidized BLES group compared with the 50 mg/kg BLES group. We conclude that instillation of an in vitro oxidized surfactant causes an inferior physiological response in a surfactant-deficient rat.
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Affiliation(s)
- Timothy C Bailey
- Department of Physiology and Pharmacology, Lawson Health Research Institute, University of Western Ontario, London, ON, Canada N6A 4V2.
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