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Development, validation and application of analytical methods to measure prognostic biomarkers in patients receiving on-pump coronary artery bypass grafting surgery Hui, Yu
Abstract
Temporary interception and then re-infusion of oxygenated blood into heart during on-pump Coronary Artery Bypass Grafting (CABG) surgery causes ischemia-reperfusion injury (IRI). Propofol is an intravenous anesthetic agent that maybe potentially cardioprotective against IRI. This thesis presents the development, validation and application of analytical methods for monitoring propofol and a series of prognostic biomarkers in hope of identifying contributory factors to IRI and propofol cardioprotection. I developed a Capillary Electrophoresis (CE) method to quantify propofol concentrations in blood. Propofol concentrations in the μg/mL range were measured from 400 μL samples. A dosefinding study using this method determined a practical infusion rate of 120 μg•kg•min⁻¹ to achieve the target blood concentration of 5 μg•mL⁻¹. To measure the oxidative stress biomarker, 15-F₂t₋isoprostane, the nitrosative stress biomarker, 3-nitrotyrosine, the myocardial protective factor, adenosine, and the cardiovascular risk factor, asymmetric dimethylarginine (ADMA), I developed simple, sensitive and robust Liquid Chromatography-Mass Spectrometry (LC-MS) or Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) methods. Briefly, a basic mobile phase and base-resistant column were used for the LC-MS analysis of 15-F₂t-isoprostane. A one-step solid phase extraction and pentafluorophenyl (PFP) core-shell column were employed for the LC-MS/MS analysis of 3- nitrotyrosine. A Strong Cation Exchange (SCX) solid phase extraction and modifier-free mobile phase were implemented for the LC-MS/MS analysis of adenosine. A new derivatization method to enable baseline separation of ADMA and its regio-isomer symmetric dimethylarginine (SDMA) was developed for the ADMA LC-MS/MS quantitation. Performance parameters for these methods, including linearity, precision, accuracy, Limit of Detection (LOD), Limit of Quantitation (LOQ), Lower Limit of Quantitation (LLOQ) and stability were found satisfactory. Concentrations of 15-F₂t₋isoprostane, 3-nitrotyrosine and adenosine were found to rise after on-pump CABG surgery. However, these changes were not able to explain the cardioprotective effect of propofol. Nonetheless, the correlations of 15-F₂t₋isoprostane with diabetes, glucose concentration and PTEN level were significant. Patients with low cardiac output syndrome experienced more 3-nitrotyrosine increase than patients without this syndrome. The basal adenosine level was found to increase more in patients with low left ventricular ejection fraction. These findings and the underlying methodologies are important for identifying new prognostic biomarkers.
Item Metadata
Title |
Development, validation and application of analytical methods to measure prognostic biomarkers in patients receiving on-pump coronary artery bypass grafting surgery
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2013
|
Description |
Temporary interception and then re-infusion of oxygenated blood into heart during on-pump
Coronary Artery Bypass Grafting (CABG) surgery causes ischemia-reperfusion injury (IRI).
Propofol is an intravenous anesthetic agent that maybe potentially cardioprotective against IRI. This
thesis presents the development, validation and application of analytical methods for monitoring
propofol and a series of prognostic biomarkers in hope of identifying contributory factors to IRI and
propofol cardioprotection.
I developed a Capillary Electrophoresis (CE) method to quantify propofol concentrations in
blood. Propofol concentrations in the μg/mL range were measured from 400 μL samples. A dosefinding
study using this method determined a practical infusion rate of 120 μg•kg•min⁻¹ to achieve
the target blood concentration of 5 μg•mL⁻¹.
To measure the oxidative stress biomarker, 15-F₂t₋isoprostane, the nitrosative stress
biomarker, 3-nitrotyrosine, the myocardial protective factor, adenosine, and the cardiovascular risk
factor, asymmetric dimethylarginine (ADMA), I developed simple, sensitive and robust Liquid
Chromatography-Mass Spectrometry (LC-MS) or Liquid Chromatography Tandem Mass
Spectrometry (LC-MS/MS) methods. Briefly, a basic mobile phase and base-resistant column were
used for the LC-MS analysis of 15-F₂t-isoprostane. A one-step solid phase extraction and
pentafluorophenyl (PFP) core-shell column were employed for the LC-MS/MS analysis of 3-
nitrotyrosine. A Strong Cation Exchange (SCX) solid phase extraction and modifier-free mobile
phase were implemented for the LC-MS/MS analysis of adenosine. A new derivatization method to
enable baseline separation of ADMA and its regio-isomer symmetric dimethylarginine (SDMA) was
developed for the ADMA LC-MS/MS quantitation. Performance parameters for these methods,
including linearity, precision, accuracy, Limit of Detection (LOD), Limit of Quantitation (LOQ),
Lower Limit of Quantitation (LLOQ) and stability were found satisfactory.
Concentrations of 15-F₂t₋isoprostane, 3-nitrotyrosine and adenosine were found to rise after
on-pump CABG surgery. However, these changes were not able to explain the cardioprotective
effect of propofol. Nonetheless, the correlations of 15-F₂t₋isoprostane with diabetes, glucose
concentration and PTEN level were significant. Patients with low cardiac output syndrome
experienced more 3-nitrotyrosine increase than patients without this syndrome. The basal adenosine
level was found to increase more in patients with low left ventricular ejection fraction. These
findings and the underlying methodologies are important for identifying new prognostic biomarkers.
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Genre | |
Type | |
Language |
eng
|
Date Available |
2013-04-09
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
|
DOI |
10.14288/1.0073726
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2013-05
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Campus | |
Scholarly Level |
Graduate
|
Rights URI | |
Aggregated Source Repository |
DSpace
|
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International