E-Thesis 218 views 425 downloads
Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia? / ALANNA THOMAS
Swansea University Author: ALANNA THOMAS
-
PDF | E-Thesis – open access
Copyright: The author, Alanna Thomas, 2025 Distributed under the terms of a Creative Commons Attribution Non Commercial 4.0 License (CC BY-NC 4.0).
Download (7.27MB) -
PDF | E-Thesis – open access
Hawlfraint: Yr awdur, Alanna Thomas, 2025 Wedi'i ddosbarthu o dan delerau Trwydded 'Creative Commons Attribution Non Commercial 4.0' (CC BY-NC 4.0).
Download (9.48MB)
DOI (Published version): 10.23889/SUThesis.70943
Abstract
Approximately 50 million people worldwide suffer from dementia, which is characterised by memory loss and a decline in the ability to perform everyday activities. Currently, blood-based biomarkers for diagnosing neurodegenerative disorders are limited. The ‘hunger hormone’ ghrelin has previously bee...
| Published: |
Swansea
2025
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Angelini, R., Morgan, A. H., & Davies, J. S. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa70943 |
| Abstract: |
Approximately 50 million people worldwide suffer from dementia, which is characterised by memory loss and a decline in the ability to perform everyday activities. Currently, blood-based biomarkers for diagnosing neurodegenerative disorders are limited. The ‘hunger hormone’ ghrelin has previously been linked to the mediation of beneficial effects of calorie restriction on the protection of nerve cells in dementia models. Ghrelin exists in various forms, including acyl ghrelin (AG) and unacylated ghrelin (UAG). Acyl ghrelin has been shown to stimulate neurogenesis, while unacylated ghrelin inhibits the process. We have previously shown that the blood plasma AG:UAG ratio is reduced in Parkinson's disease dementia (PDD) and thus may be a potential biomarker of dementia. A major challenge is in accurately measuring these ghrelin peptides simultaneously in one assay. The main objective of this thesis is to develop a high-sensitivity mass spectrometry (MS) technique coupled with the ability to detect different species of endogenous ghrelin simultaneously from a single plasma sample. A matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) method was developed first on exogenous human ghrelin standards, employing rat ghrelin as an internal standard (ISTD). Calibration curves for exogenous ghrelin were established with a correlation coefficient (R2) value of 0.99 covering a range of 0.08-80 ng/mL of ghrelin, with endogenous ghrelin usually present at 0.32 ng/mL. A liquid chromatography-mass spectrometry (LC-MS) method was also developed; however, a detection limit was established at 0.4 ng/mL. Endogenous ghrelin was extracted from human plasma for quantification using MALDI-TOF. A range of traditional protein extraction techniques were used, such as protein precipitation followed by solid phase extraction (SPE), along with a novel approach termed bead-assisted mass spectrometry (BAMS). Initial results of this BAMS method showed greater capture of ghrelin compared to traditional SPE methods when extracting ghrelin. Additionally, compared to the enzyme-linked immunosorbent assay (ELISA), the reproducibility of the assay showed similar or better results than the reproducibility of the ELISA. The additional capability of BAMS to analyse multiple proteins from one plasma sample opens a new realm for not only ghrelin analysis but also additional blood-based biomarkers of disease. |
|---|---|
| Keywords: |
Ghrelin, Mass spectrometry, Dementia. Neurodegeneration, Bead Assisted MS, MALID-TOF, LC-MS, Solid Phase extraction, |
| College: |
Faculty of Medicine, Health and Life Sciences |
| Funders: |
Coleg Cymraeg Cenedlaethol |