http://theses.ncl.ac.uk/jspui/handle/10443/5256 Tue, 07 Apr 2026 07:02:38 GMT 2026-04-07T07:02:38Z http://theses.ncl.ac.uk/jspui/handle/10443/6704 Title: Interactive effects of ageing processes and early life stress on brain structure: a neuroimaging informatics approach Authors: Kindred, Nathan Shaun Abstract: Though it is well established that ageing and early-life stress can cause changes in brain structure, there is less agreement on both region-specific changes and how interactions between ageing and early-life stress may impact on brain structure. Investigations in humans often rely on cross-sectional studies, and are confounded by a number of drawbacks and biases. These issues can be mitigated through the use of model animals, such as rhesus macaques. However, processing macaque MRI data comes with a number of issues, precluding the use of human MRI processing pipelines. Therefore, this project first involved the creation of a novel processing pipeline for macaque MRI data. The outputs of the AutoMacq pipeline had a low error-rate and high levels of reliability. As the majority of previous studies focus on brain changes in late adulthood, this project focused on the under-researched period of early to mid-adulthood. Using a longitudinal approach, significant decreases, in both cortical thickness and grey matter volume, with ageing were identified, primarily within the frontal, temporal and parietal lobes. Early weaning was utilised as a measure of early life stress. In an age- matched cross-sectional dataset, subjects weaned before 12 months showed significantly lower cortical thickness in regions of the temporal lobe, compared to those weaned after 12 months. Significant interactions between weaning and ageing were found for grey matter volume in one area of the occipital lobe, as well for cortical thickness in regions of parietal and occipital lobes. Brain areas across the whole brain appeared sensitive to ageing, whereas regions specifically involved in visual processing seemed most affected by early weaning. Overall, this project resulted in the creation of a novel macaque MRI processing pipeline, and provided new knowledge on the impacts of ageing and early-life stress on brain structure during early to mid-adulthood. Description: Ph. D. Thesis Wed, 01 Jan 2025 00:00:00 GMT http://theses.ncl.ac.uk/jspui/handle/10443/6704 2025-01-01T00:00:00Z http://theses.ncl.ac.uk/jspui/handle/10443/6699 Title: The Role of Tumour Microenvironmental Signals in TP53-dependent Therapeutic Strategies for Chronic Lymphocytic Leukaemia (CLL) Authors: Howladar, Mohammed Abstract: Chronic lymphocytic leukaemia (CLL) is a haematologic malignancy of B cells that shows a highly heterogeneous clinical course, with approximately 90% of patient CLL samples being wild type for the TP53 tumour suppressor gene at diagnosis. CLL accounts for approximately 1000 deaths annually in the United Kingdom alone, highlighting the need to unravel the molecular mechanisms that could be used to produce more effective treatment options. Since TP53 disruption by either mutation and/or deletion occurs in only 10-15% of CLL cases, targeting MDM2 to activate TP53 in a non-genotoxic manner is a potential treatment strategy for wild type TP53 CLL. In this study, the combination of WIP1 inhibitor (GSK2830371) with RG7388 was investigated to potentiate the stabilization and pro-apoptotic effects of wild type TP53 at lower concentrations. The potential effect of the microenvironment on the response to MDM2 and WIP1 inhibitors was modelled ex-vivo, including the stimulation of CLL cells with CD40 ligand (CD40L), IL-4 and B cell receptor (BCR) signalling with anti-IgM treatment. The results identified that WIP1 inhibitor potentiated the effect of the MDM2-p53 binding antagonist (RG7388) in wild type TP53 haematological cell lines and non-proliferative CLL cells. The stabilization activity of TP53 was confirmed by the induction of downstream target genes. Furthermore, ex-vivo combined CD40L/IL-4 stimulation showed the proliferative CLL cells became more sensitive to RG7388 as a single agent treatment. The WIP1 inhibitor potentiated the effect of RG7388 and increased the expression of TP53 dependent pro-apoptotic genes. Both immobilized anti-IgM antibody and IL-4 signalling induced proliferation and cell survival signals, which was associated with the ex-vivo primary CLL cells becoming less sensitive to RG7388, and under these conditions the combination with WIP1 inhibitor also did not significantly potentiate the TP53 stabilization by RG7388. However, in the presence of IL-4 the expression of TP53 downstream target genes showed a transcriptional induction of the TP53-dependent pro-apoptotic gene (PUMA) and negative regulator of TP53 (MDM2). In summary, the WIP1 inhibitor (GSK2830371) significantly potentiated the effect of non-genotoxic small molecule MDM2 inhibitor (RG7388) in functional TP53 CLL cells. Modelling the ex-vivo microenvironment with CD40L, IL-4 and BCR activation with anti-IgM antibody was found to reduce the sensitivity of the CLL cells to both single agent RG7388 and when in combination with GSK2830371. This highlighting the importance of the in-vivo microenvironment and the need to develop combination strategies that overcome its limiting effect on the response to p53-dependent therapies. Description: Ph. D. Thesis. Wed, 01 Jan 2025 00:00:00 GMT http://theses.ncl.ac.uk/jspui/handle/10443/6699 2025-01-01T00:00:00Z http://theses.ncl.ac.uk/jspui/handle/10443/6698 Title: Investigating the mechanism of dietary fibre breakdown by the human and animal gut microbiota Authors: Hinkley, Cosette Elizabeth Abstract: The intestinal tracts of mammalian species are inhabited by a complex community of microbes, known collectively as the gut microbiota. Many bacterial members of the gut microbiota play an important role in the degradation of complex dietary carbohydrates. Hemicelluloses are plant polysaccharides, often degraded by the gut microbiota; however these are generally tightly associated with cellulose, which is more recalcitrant to breakdown. Xylans are amongst the most abundant hemicelluloses within the human and animal diet. Here, we initially investigated the xylan-degrading capabilities of members of the Bacteroidota phylum and show that ability to utilise different types of xylan is widespread but not ubiquitous. Furthermore, we demonstrate the ability to bioinformatically predict xylan utilisation capabilities for gut Bacteroidota. Highly decorated xylans, such as those from cereal brans, are generally recalcitrant to breakdown by endoxylanases but have previously been shown to be cleaved by a GH98 enzyme from the human gut symbiont Bacteroides ovatus. GH98 enzymes have also been shown to be β1,4-galactosidases targeting blood group sugars. Here we present structural and functional studies into Bo98 endoxylanase to investigate the mechanism of complex cereal xylan targeting by this enzyme and reveal how the same family can possess specificity for both xylans and blood group sugars. We also show that that other gut and non-gut derived GH98 enzymes display the same specificity as Bo98. Furthermore, these GH98 endoxylanases possess a conserved CBM35 domain, which we show is a functional carbohydrate binding protein, recognising a range of arabinose-containing hemicelluloses at a novel binding site for the family. Finally, we show that human gut Bacillota Ruminococcus champanellensis is capable of growth on cellulose and a whole corn cell wall substrate. We present plans for future experiments examining gene upregulation during growth on these substrates. These data will provide insights into the plant cell wall degrading strategy of this keystone Bacillota from the human gut. This investigation demonstrates that members of the gut microbiota have developed diverse glycan utilising strategies and preferences, allowing survival of individual species in a highly populated ecological niche Description: Ph. D. Thesis. Wed, 01 Jan 2025 00:00:00 GMT http://theses.ncl.ac.uk/jspui/handle/10443/6698 2025-01-01T00:00:00Z http://theses.ncl.ac.uk/jspui/handle/10443/6696 Title: Digestive enzyme modulating properties of Kuwait seaweed and seaweed extracts Authors: Alshammari, Hebah Atiya Abstract: The primary aim of this research was to investigate the inhibitory impact of Kuwait seaweed and its aqueous (WE) and ethanolic extracts on Pancreatic Lipase (PL) utilising turbidity assay, Michaelis-Menten kinetic analysis, and a synthetic model of the gut system. Next, the total polyphenolic content (TPC) was measured. A total of seven seaweeds, belonging to various species, were collected from the Kuwait coastline between 2019 and 2022. The green seaweeds identified were Cladophora sericioides and Codium papillatum. The brown seaweeds identified were Sirophysalis trinodis, Colpomenia sinuosa, Iyngaria stellata, and Padina boergesenii. The red seaweed was Gelidium Pusillum. The brown seaweed S. trinodis was harvested during two distinct seasons, November 2020 (N) and April 2021 (A). Therefore, the temporal effect on the inhibitory action of S. trinodis was investigated. It was found that all Kuwaiti seaweed homogenates, as well as four WE extracts and four ethanol pellets, showed significant inhibition of PL activity to varying extents. These samples were used for further research. The kinetic analysis revealed that Kuwaiti seaweed samples showed mixed-type inhibition of pancreatic lipase. The Kuwait seaweed samples did not inhibit fat digestion. It has been determined that Kuwaiti seaweeds contain varying concentrations of TPC. However, no correlation was found to be statistically significant between seaweed TPC and its PL inhibitory effect. The significant temporal effect on PL activity and TPC were noted in the WE extract from S. trinodis. The observed variance in the results across seaweed species suggests that each seaweed is likely harbours species-specific compounds with distinctive structural features. The ani-lipase properties of the phytochemicals found in Kuwaiti seaweed samples are due to their additive and synergistic effects. Description: PhD Thesis Wed, 01 Jan 2025 00:00:00 GMT http://theses.ncl.ac.uk/jspui/handle/10443/6696 2025-01-01T00:00:00Z