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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

DNA methylation as a biomarker for age-related cognitive impairment

Barrett, Laura Michelle January 2015 (has links)
Due to the ageing population, the number of patients diagnosed with age-related diseases such as stroke and Parkinson’s disease are on the rise. In both post-stroke dementia (PSD) and mild cognitive impairment in Parkinson’s disease (PD-MCI), the mechanisms resulting in cognitive decline are unknown. This project aims to identify a biomarker which could predict those patients most at risk of developing cognitive decline, which would subsequently assist healthcare professionals in recommending early treatment and care. Epigenetics is an emerging field in which biomarkers have previously been useful in prognostication of cancers and prediction of cardiovascular disease. In this study, 30 patients from a PSD cohort (COGFAST) and 48 patients from a PD-MCI cohort (ICICLE) were analysed using the Illumina HumanMethylation450 BeadChip to identify differentially methylated positions which could predict patients who would later develop cognitive decline. Top hits were validated using Pyrosequencing to confirm DNA methylation differences in a replication cohort. Individual CpG sites within APOB and NGF were identified as potential blood-based biomarkers for PSD and one CpG site within CHCHD5 was highlighted as a potential blood-based biomarker for PD-MCI. In addition, methylation at one CpG site within NGF and a CpG site (cg18837178) within a non-coding RNA, were found to be associated with Braak staging (degree of brain pathology) using DNA from two brain regions. NGF deregulation has previously been associated with Alzheimer’s disease, and this finding indicates it may also have a role in the development of PSD. These novel findings represent the first steps towards the identification of blood-based biomarkers to assist with diagnosis of PSD and PD-MCI, but require further validation in a larger independent cohort. The differentially methylated genes identified may also give insight into some of the mechanisms involved in these complex diseases, potentially leading to the future development of targeted preventative treatments.

Metabolic syndrome and psychosis in Alzheimer's disease

Benjamin, Boben January 2014 (has links)
The metabolic syndrome is a constellation of vascular risk factors including abdominal obesity, hypertension, diabetes, hypertriglyceridaemia and low high density lipoprotein cholesterol. The aim of the study was to explore the link between the metabolic syndrome and its components, and psychosis in Alzheimer’s disease. The participants were selected from the Human Serum Metabolome Project. 246 participants with Alzheimer’s disease were assessed at baseline and 151 were followed up a year later. The neuropsychiatric inventory was used to capture information about psychiatric symptoms including delusions and hallucinations. The vascular risk factors were determined from the history from the participant and carer; abdominal obesity however was measured during the study. Hypertriglyceridaemia and high density lipoprotein cholesterol data were unavailable and so the study focuses on the link between the metabolic syndrome components of obesity, hypertension and diabetes, and psychosis in Alzheimer’s disease. Although not part of the metabolic syndrome criteria, a history of hypercholesterolaemia was used in conjunction with the available metabolic syndrome components and the link between the resulting vascular syndrome and psychosis in Alzheimer’s disease was studied. Two measure of psychosis were used for the research. First of all, a factor representing psychosis was derived by factor analysis of the neuropsychiatric inventory data. Secondly, a direct measure of psychosis using the delusions and hallucinations items from the neuropsychiatric inventory was used. Cross-sectional and longitudinal analyses were conducted. The majority of the analyses conducted failed to find a significant link between the measures. Male sex, a lower Mini Mental State Examination score as well as the use of antipsychotics and memantine were found to be significantly associated with psychosis at baseline. Overall this study does not support the link between the metabolic syndrome or its components and psychosis in Alzheimer’s disease. Future research looking at subsets of Alzheimer’s patients with more clearly defined lipid triglyceride and high density lipoprotein cholesterol data will be useful.

The regulation of endothelial cell activation by the extracellular matrix after acute brain injury

Kangwantas, Korakoch January 2014 (has links)
Inflammation or injury of the central nervous system generally results in the activation of brain endothelial cells and a change in the composition and expression of the extracellular matrix (ECM) network of the basal lamina of the brain vasculature. The main contributors to brain damage are interleukin (IL)-1-mediated inflammatory processes. The main aim of this project is to investigate whether the ECM associated with brain endothelial cells is modified in response to ischaemic injury in vitro, and to test the hypothesis that alteration of ECM composition following injury is a critical regulator of IL-1-induced endothelial cell activation. The in vitro blood-brain barrier model used in this thesis was composed of brain endothelial cells and astrocytes and this model displayed classic BBB characteristics. Oxygen-glucose deprivation (OGD) for 2.5 hours followed by 4 hours of reperfusion ± 10 ng/ml IL-1β induced changes in rat brain endothelial cell (rBEC) morphology, occludin and ZO-1 distribution and cytokine-induced neutrophil chemoattractant (CINC)-1 release. Immunohistochemistry on brain sections from animals subjected to middle cerebral artery occlusion (MCAO) demonstrated upregulation of laminin α4 protein following 48 hours and 6 days of reperfusion. Fibronectin expression was also increased in the brain vessels of animals subjected to MCAO following 48 hours of reperfusion. Similarly, 2.5 hours OGD and 2 hours reperfusion ±IL-1β induced changes in laminin α4, β1 and γ1, type IV collagen α1 chain and fibronectin mRNA expression in vitro. ECM molecules also influenced rBEC morphology, adhesion, proliferation, organisation and TEER. Integrin β1 mediated rBEC adhesion to type I collagen, type IV collagen and cellular fibronectin but not laminin-511 and the combination of laminin-411 and -511. Laminin-511 and the combination of laminin-411 and -511 significantly increased CINC-1 release compared to type I collagen. Laminin-411 and -511 also upregulated occludin protein expression and maintained occludin distribution following IL-1β treatment in rBECs. To conclude, ECM associated with brain endothelial cells was modified in response to ischaemic injury ±IL-1β in vitro, and vascular ECM proteins altered rBEC activation in response to IL-1β. Therefore, a change in ECM composition following injury is a critical regulator of IL-1-induced endothelial cell activation.

The early diagnosis and management of Creutzfeldt-Jakob disease

Cordery, R. J. January 2004 (has links)
This thesis describes work undertaken to improve the early diagnosis of variant Creutzfeldt-Jakob disease (vCJD), using existing clinical and research tools. Twenty-one cases referred to the National Hospital for Neurology and Neurosurgery and St. Mary's Hospital, London with suspected vCJD completed participation in the study. Fifteen cases were confirmed with definite or probable vCJD and six were given alternative diagnoses. These six cases with alternative diagnoses formed a control group. Further controls were recruited from patients referred with sporadic and familial forms of prion disease. A neuropsychiatry questionnaire comprising a battery of standardised tests was formulated. Of those with definite or probable vCJD, 86% exhibited anxiety, 93% irritability, 64% agitation and 79% displayed evidence of severe depressive symptoms. Fifty seven percent experienced simple delusions, most commonly of theft and suspicion and 36% described misidentifications (mean 8 months from illness onset). Behavioural change was common to all cases, 79% with aggression, 71% emotional lability and 79% sleep problems. Comprehensive neuropsychology assessments from those with vCJD were compared with sporadic and familial cases. Moderate to severe intellectual decline is characteristic of vCJD and impairment affects all cognitive domains. Only a minority of the vCJD cases presented with perceptual impairment compared with 50% of sporadic and familial cases. The proportion of cases with nominal impairment in the familial disease group was significantly lower than in the variant and sporadic groups. Serial volumetric MR imaging was only possible in a subgroup of cases with familial CJD. The annual mean rate of whole brain atrophy was 2.05% compared to 0.25% in normal controls. Single voxel proton magnetic spectroscopy performed in three cases with vCJD showed a 2.5 fold (150%) increase in the mean myo-inositol concentration and 50% reduction in N-acetylaspartate in the pulvinar region. Similar changes were seen in the caudate nucleus where no signal change was detected on T2 weighted images. The key to early diagnosis still relies on a high index of suspicion for vCJD and early referral to the appropriate specialist services. First hand experience of the problems faced by patients prompted a second, parallel project to be undertaken. A survey was conducted of all UK consultant neurologists and old age psychiatrists to assess current practices in the diagnosis and management of young people with dementia. It was concluded that young people may be under investigated if managed solely by an old age psychiatrist and may not receive adequate follow up services if managed solely by a neurologist.

The impact of information on illness representations and coping in early dementia from the perspective of the person with dementia : a phenomenological approach

Harman, G. January 2004 (has links)
The onset of chronic illness often leads to threats to perceptions of self identity and challenges to prior ways of living. The self-regulation model of illness behaviour of Leventhal, Nerenz and Steele (1984) has provided a framework for understanding how people may manage these threats to self. To date this has been applied predominantly to physical illnesses and a few chronic neurological illnesses including Motor Neurone Disease. Whilst there have been several studies which have looked at the experience of people with early dementia, none has used the self-regulation model as a framework. A semi-structured interview methodology was used to explore the following questions. What representations do people with early-stage dementia have following diagnosis How do people's representations relate to the experience of early-stage dementia and how they manage it What are the implications for theory from what people tell us about their experience Interpretative Phenomenological Analysis (IPA) was used to analyse the data from the interview transcripts. This approach attempts to understand people's beliefs about a given topic through the assumption that there is an indirect link between what people report and underlying cognitions. IPA is a phenomenological approach in that it is concerned with individual subjective accounts and beliefs about objects or events and interpretive in that these accounts are elicited through a dynamic process in which the researcher's own beliefs play a part as they interpret data. Two overarching themes emerged from the analysis. These themes are 'Understanding Dementia: It Will Get Worse', which represents the individual's knowledge and representations of dementia, and 'I Want To Be Me', which represents the lived experience of adapting to dementia. The first of these themes is constructed from a number of sub-themes. 'I Want To Be Me' has two components of 'Personal Dilemmas: Where Do I Stand' and 'Interpersonal Dilemmas: The Line Is Crossed', each of which is also constructed of further sub-themes. The results were discussed in relation to each of the research questions in turn. It was then considered how the results add to the understanding of the experience of early dementia. A tentative model of how illness representations contribute to the lived experience is suggested. Areas for future research in the field that emerged from the study were discussed including the potential of exploring and comparing the representations of different groups of people. Possible methodological limitations of the study were explored in the context of the implications these may have had for the wider applicability of the results and how the researcher's assumptions and experience may have influenced the outcome of the study. Finally, implications for clinical practice arising from the study were discussed. These included the need to recognise the importance of directly involving people with dementia in the diagnosis sharing process, if they so choose and how people with early stage-dementia may be helped in maintaining their sense-of-self whilst adjusting to dementia related changes.

The effect of organisational support on care staff attributions about, emotional reactions to, and self-efficacy in managing challenging behaviour

Head, D. January 2004 (has links)
This is a quantitative study focussing on the experiences of paid carers working with people who have learning disabilities and challenging behaviour. Staff working with people displaying these behaviours are likely to experience high levels of stress and face significant challenges in understanding and managing this behaviour. This study assessed the amount of support carers for people with learning disabilities and challenging behaviour receive from the organisations they work for, and how helpful they find this in managing the challenging behaviour of their residents. This support includes supervision, training and team meetings. It assessed the attributions made by care staff about the causes of challenging behaviour, their emotional reactions to challenging behaviour and their perceived self-efficacy in managing this behaviour, using previously developed scales. Organisational support was measures using two scales. A previously validated measure was used to assess general perceptions of a supportive environment, whilst a new measure was designed to assess aspects of support given around challenging behaviour. 66 participants were recruited from 13 residential units in three London boroughs. Significant links were found between staff support and self-efficacy, and self- efficacy and negative emotional reactions to challenging behaviour. Both staff support related to challenging behaviour and more general features of a supportive organisation were found to be important in promoting self-efficacy. The measure designed for this study showed promise as a quick, reliable method of assessing staff support around challenging behaviour. Limitations of the study, clinical implications and future directions for research are discussed.

Alterations in the cerebrospinal fluid relating to apolipoprotein E after traumatic brain injury and subarachnoid haemorrhage

Kay, A. D. January 2004 (has links)
Background: The human gene coding for apolipoprotein E is polymorphic, and the APOE4 allele has been associated with less favourable outcome after acute brain injury including traumatic brain injury (TBI) and subarachnoid haemorrhage (SAH). Experimental studies identify key roles for apoE in the central nervous system such as the scavenging and recycling of lipids for cellular maintenance and repair and formation of cerebral amyloid aggregate. Human in-vivo evidence supporting the concept that apoE is involved in the response of the brain to acute injury is sparse. Objectives: This study tests the hypothesis that apoE is involved in the response of the human brain to injury, and this role is reflected by changes in cerebrospinal fluid (CSF) apoE concentration after brain injury which correlate with injury severity and outcome. In addition it was hypothesised that changes in apoE concentration would be paralleled by changes in the composition of CSF lipoprotein particles (Lps) of which apoE is a major component. Lastly, apoE is reported to chaperone amyloid-beta peptide (Abeta), therefore we hypothesised that alteration in CSF apoE after brain injury would parallel alterations in Abeta. Methods: Enzyme linked immunosorbant assay (ELISA) was used to determine the concentration of apoE, Abeta, S100B and Tau (as surrogate markers of brain injury) in CSF from TBI and SAH patients and a non-brain injured control group. Lipoprotein particles were isolated from CSF using size exclusion chromatography and characterised in relation to cholesterol, phospholipid, apolipoprotein E, and apohpoprotein AI composition. Injury severity was determined using the Glasgow Coma Score, and clinical outcome using the Glasgow Outcome Score. Results: Compared to controls there was a sustained decrease in the concentration of apoE in the CSF after TBI and SAH which was paralleled by a depletion of apoE containing lipoprotein particles. Furthermore, CSF Abeta also decreased, and the decrease correlated with injury severity and clinical outcome. In contrast the levels of S100B and Tau in brain injury CSF was substantially elevated. Conclusion: Despite the likely leakage of plasma apolipoprotein E into the subarachnoid space at the time of brain injury, apoE in the form of LpE is cleared from the CSF within days of injury. In addition, indirect evidence suggesting apoE-Abeta interactions in-vivo support the concept that apoE may form insoluble aggregates with Abeta soon after brain injury. The finding that these alterations in the CSF correlate with injury severity and outcome provides novel indirect in-vivo evidence that apoE is important to the response of the human brain to injury.

Functional recovery after brain injury rehabilitation

McPherson, Kathryn Margaret January 1998 (has links)
The thesis has two main research goals. Firstly:- a descriptive study explored functional status in patients after brain injury following discharge from in-patient rehabilitation to their own homes in the community. Secondly:- an intervention study was carried out to explore the role of home based visits as part of post discharge follow-up of patients after inpatient rehabilitation to address the findings of the first study. In the first study, 89 patients admitted consecutively for early inpatient rehabilitation following a traumatic of haemorrhagic brain injury were visited at home by the researcher at six weeks after discharge and again at 15 months. Assessment using a number of measures of function characterised the disabilities that patients experienced and revealed that deterioration in everyday functioning was common after discharge home. These two factors led to the intervention study where 43 patients were recruited to evaluate whether visits to the patient's home in the early weeks after discharge would prevent deterioration and satisfy the carers' requests for information and support. Randomisation using the minimisation method led to an experimental group with 21 subjects and a control group with 22. Patients in the experimental group were visited weekly until the sixth week when both groups were assessed using a wide range of functional measures. Both groups were also assessed at 15 months after injury. The experimental group deteriorated less than the control group in the early post-discharge period and patients, carers and other professionals valued the service provided. However, this functional improvement was not maintained at the 15 month follow-up in some cases and factors contributing to this are discussed.

The aetiology and prevention of ischaemic stroke associated with recently symptomatic atherothrombotic carotid artery stenosis : lessons from a randomised controlled trial of carotid endarterectomy

Rothwell, Peter M. January 1999 (has links)
The cost-effectiveness of carotid surgery, which is questioned by many, would be increased considerably if it was possible to predict the risks and likely benefits for individual patients. This was the main aim of the work described in this thesis. This was achieved in five stages. Firstly, using carotid angiograms from 3007 patients randomised in the European Carotid Surgery Trial (ECST), I determined the equivalence, reproducibility and pathological correlation of the assessment of plaque surface morphology on angiograms. Secondly, using data on patients randomised to no-surgery in the ECST, I studied the relationship between the degree of carotid stenosis, plaque surface morphology and other clinical and angiographic characteristics and the risk of ipsilateral carotid territory ischaemic stroke on medical treatment. Using both a simple univariate approach and a multivariate Cox's proportional hazards approach, I was able to develop a number of prognostic models. Thirdly, I studied the risk of stroke and death due to carotid endarterectomy using a systematic review of the published literature. The absolute risk of stroke and death due to surgery was defined with narrow confidence limits and the relationship between various clinical and angiographic characteristics and the operative risk was determined. The validity of the risk factors for operative stroke and death were derived from the systematic review and the interaction with surgical and anaesthetic technique was assessed using data on patients randomised to surgery in the ECST. Fourthly, the potential benefit of selecting patients for carotid endarterectomy on the basis of the balance between their predicted individual risks of stroke on medical treatment and stroke and death due to surgery was assessed by stratifying the results of the ECST by baseline risk and by applying the same prognostic models to data from the North American Symptomatic Carotid Endarterectomy Trial. Finally, I designed and set up two large international collaborative studies which aim to further define the prognostic factors for major ischaemic stroke and other vascular outcomes in patients presenting with transient ischaemic attacks and minor ischaemic stroke and increase the cost-effectiveness of stroke prevention using carotid endarterectomy.

Messenger RNA studies in Alzheimer's disease

Wighton-Benn, Wendy Helen January 1999 (has links)
In this thesis, <i>in situ</i> hybridisation histochemistry was the principal technique applied to the study of a number of specific species of messenger RNA (mRNA) in tissue from normal and diseased post-mortem human brains. Gs and Go are members of the heterotrimeric G protein family whose members are crucial to cellular responsiveness. APP and Goa mRNA levels were found to be reduced in the dentate gyrus of AD sufferers in comparison to controls and were positively correlated in this region irrespective of diagnosis. The APP gene is encoded on chromosome 21 and APP mRNA levels are increased in Down's syndrome in keeping with the 50% increase in gene dosage associated with trisomy 21 (Tanzi <i>et al.</i> 1987). Increased APP mRNA levels are postulated to be responsible for the early appearance of the pathological stigmata of AD in individuals with this condition. However, a comprehensive analysis of APP mRNA levels in the hippocampus and visual cortex of diseased and control brains concluded that increased APP mRNA levels are not a feature of AD. An increase in the ratio of potentially amyloidogenic KPI-encoding, relative to KPI-lacking, APP mRNA transcripts was documented with age in the visual cortex of diseased and control brains. Further, the major determinant of this ratio differed between the visual cortex and the hippocampus. Ubiquitin is a highly conserved member of the heat shock protein family essential to ATP-dependent non-lysosomal proteolysis. Ubiquitin mRNA, when expressed as a proportion of polyadenylated mRNA, was increased in the visual cortex of individuals diagnosed as suffering from borderline AD in comparison to the other diagnostic groups studied. The implications of the above findings in relation to the pathogenesis of AD and the challenges inherent in the application of biomedical research techniques to the study of a uniquely human disease like AD, using human post-mortem brain tissue, are discussed.

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