Publication Date

2024

Document Type

Dissertation/Thesis

First Advisor

Gaillard, Elizabeth R.

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Chemistry and Biochemistry

Abstract

Chronic inflammation and dysfunctional inflammatory responses are believed to be contributing factors to the severity of many diseases. Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it has been recognized that levels of inflammatory markers and the severity of coronavirus disease-2019 (COVID-19) cases are closely related. The work within this dissertation begins with establishing an alternative platform for the diagnosis of COVID-19 and explores ways to enhance the diagnostic utility of this platform. An alternative route for COVID-19 diagnosis was explored using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). The platform utilizes a non-invasive sampling technique and is relatively rapid with few sample preparation steps. To establish the method, the protein profiles of human gargle samples acquired by MALDI-ToF MS were compared to the COVID-19 status. Five biomarkers, potentially representing human immune proteins and viral proteins, were identified and demonstrated 90% or higher agreement with the COVID-19 status. A major component of human gargle samples is salivary amylase, which dominates the protein profiles acquired by MALDI-ToF MS. The effects of depleting amylase on the mass spectra were studied by passing samples through an inexpensive device that selectively captures amylase. The amylase-depleted protein profiles revealed peaks previously unobserved and contained signals of higher intensities. The depletion of amylase from gargle samples enhanced the protein profiles, resulting in 85.17% sensitivity and 100% specificity for the diagnosis of COVID-19. Inflammation is also thought to play a key role in the progression of age-related macular degeneration (AMD), which is a major cause of blindness in adults. Accumulation of the age- related pigment lipofuscin is associated with retinal inflammation and macular degeneration. The association of lipofuscin with melanin in the retinal pigment epithelium (RPE) is thought to be closely linked to the progression of macular degeneration as well. Removal of lipofuscin is therefore a suggested therapeutic option and is being explored through treatments involving generators of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Studies show such treatments depend on the chemical or physical properties of melanin to degrade lipofuscin. In this dissertation work, the mechanism through which ROS/RNS may degrade lipofuscin was explored using liquid chromatography-mass spectrometry (LC-MS). Using serotonin as a small molecule model of melanin, oxidation products from the action of horseradish peroxidase in the presence of hydrogen peroxide were investigated. Detection of an ion with m/z = 209 supports the possible formation of a dioxetane intermediate and subsequent cleavage into two carbonyls. Such mechanistic studies are needed to better understand the potential pathways through which levels of lipofuscin may be modulated in the retina via melanin or through the introduction of therapeutics.

Extent

198 pages

Language

en

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

Download

Share

COinS