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Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia? / ALANNA THOMAS

Swansea University Author: ALANNA THOMAS

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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...

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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
first_indexed 2025-11-19T16:31:01Z
last_indexed 2025-11-21T09:55:39Z
id cronfa70943
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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. 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spelling 2025-11-19T16:42:20.5170637 v2 70943 2025-11-19 Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia? 47915f380d0fc9de1787731e3cf4ccbd ALANNA THOMAS ALANNA THOMAS true false 2025-11-19 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. E-Thesis Swansea Ghrelin, Mass spectrometry, Dementia. Neurodegeneration, Bead Assisted MS, MALID-TOF, LC-MS, Solid Phase extraction, 5 11 2025 2025-11-05 10.23889/SUThesis.70943 COLLEGE NANME COLLEGE CODE Swansea University Angelini, R., Morgan, A. H., & Davies, J. S. Doctoral Ph.D Coleg Cymraeg Cenedlaethol Coleg Cymraeg Cenedlaethol 2025-11-19T16:42:20.5170637 2025-11-19T16:11:30.1890971 Faculty of Medicine, Health and Life Sciences Swansea University Medical School - Biomedical Science ALANNA THOMAS 1 70943__35665__7c375c775f91466594cebd86039c15c2.pdf 2025_English_Thomas_A.final.70943.pdf 2025-11-19T16:30:19.6944776 Output 7622918 application/pdf E-Thesis – open access true 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). true eng https://creativecommons.org/licenses/by-nc/4.0/ 70943__35666__00fe9b12fbb94a2782f5277b60cc77cf.pdf 2025_Cymraeg_Thomas_A.final.70943.pdf 2025-11-19T16:33:41.3516957 Output 9939648 application/pdf E-Thesis – open access true 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). true cym https://creativecommons.org/licenses/by-nc/4.0/
title Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
spellingShingle Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
ALANNA THOMAS
title_short Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
title_full Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
title_fullStr Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
title_full_unstemmed Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
title_sort Detection of Ghrelin Species by Mass Spectrometry, a Novel Biomarker for Diagnosing Dementia?
author_id_str_mv 47915f380d0fc9de1787731e3cf4ccbd
author_id_fullname_str_mv 47915f380d0fc9de1787731e3cf4ccbd_***_ALANNA THOMAS
author ALANNA THOMAS
author2 ALANNA THOMAS
format E-Thesis
publishDate 2025
institution Swansea University
doi_str_mv 10.23889/SUThesis.70943
college_str Faculty of Medicine, Health and Life Sciences
hierarchytype
hierarchy_top_id facultyofmedicinehealthandlifesciences
hierarchy_top_title Faculty of Medicine, Health and Life Sciences
hierarchy_parent_id facultyofmedicinehealthandlifesciences
hierarchy_parent_title Faculty of Medicine, Health and Life Sciences
department_str Swansea University Medical School - Biomedical Science{{{_:::_}}}Faculty of Medicine, Health and Life Sciences{{{_:::_}}}Swansea University Medical School - Biomedical Science
document_store_str 1
active_str 0
description 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.
published_date 2025-11-05T05:34:01Z
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score 11.096027

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