Search

Borrelia burgdorferi sensu lato (s.l.) is the causative agent of the tick-borne zoonotic disease Lyme borreliosis (LB), of which around 2-3000 cases are reported annually in the UK. This project took a "One Health" approach to studying Borrelia burgdorferi s.l. in southern Cumbria exploring its medical and veterinary importance and quantifying the environmental hazard it presents in the region. Under a "One Health" umbrella, this project comprised of three discrete studies: (1) a longitudinal study of tick population dynamics, and B. burgdorferi s.l. transmission dynamics in these ticks, was carried out between June 2013 and September 2017 in three separate but closely located woodlands, (2) the role of grey squirrels (Sciurus carolinensis) in the natural maintenance of B. burgdorferi s.l. was assessed, and (3) a veterinarian-based survey of ticks infesting companion animals was completed. The most noteworthy findings in these studies were: (1) the phenologies of the three questing tick populations studied were similar, but there was consistent and significant variation in tick abundance between the three populations. Overall tick abundance rose during the study. B. burgdorferi s.l. circulated in all three tick populations, but at significantly different prevalences. The annual density of infected ticks varied significantly at all three sites but this variation was asynchronous. Four Borrelia genospecies were encountered in the study, but the relative contribution of each to the borrelial community varied markedly between populations and but stayed constant through time. (2) Grey squirrels were susceptible to B. burgdorferi s.l. (prevalence 19.74%) and infection with all four Borrelia genospecies was encountered. The prevalence of infections in ticks feeding on squirrels was almost 11.57% significantly higher than that in local questing tick populations (3.69%). (3) Three Ixodes species parasitized companion animals, with I. ricinus being the most common. Parasitism peaked in July. Infection rate in companion animal-associated I. ricinus ticks was 1.29%, was significantly lower than that observed in questing ticks. This thesis provides an insight into tick phenology and what species of ticks bite companion animals in the area. Although the peak in tick bites on companion animals did not coincide with the peak in questing ticks from the longitudinal study this can be explained by behaviour and species of ticks. Regarding B. burgdorferi s.l. infections in questing ticks tend to fluctuate throughout the year with cases of temporary absence at some sites. Infection prevalence in ticks from companion animals was lower than that found in questing ticks and grey squirrels had a high prevalence of infection particularly B. afzelii and B. garinii. Both of which dominated sites during the longitudinal study. This holistic approach to disease ecology shows that B. burgdorferi should not only be discussed in regard to human disease but to explore the wider concept to gain a better insight into the spirochetes place in the world.

Background: Burden is well documented among carers of stroke survivors, yet current evidence is insufficient for determining the best strategies for reducing negative outcomes. The Medical Research Council (MRC) framework advocates using theories in intervention development, but lacks guidance on how this can be achieved. Interventions targeting carers of stroke survivors often lack theory or provide inadequate descriptions of the active ingredients determining their effects. This research aimed to develop a proposed theory- and evidence-based intervention to reduce burden in carers of stroke survivors. Methods: In conjunction with stakeholder involvement, Intervention Mapping stages one to four guided intervention development: needs assessment; identifying outcomes and objectives; selecting theoretical methods and practical applications; and creating a programme plan. The needs assessment included three components: A systematic review of systematic reviews established the factors that influence burden in carers of stroke survivors and other longer-term conditions; a thematic synthesis of qualitative studies and a qualitative interview study established carers’ needs, how and whether they change over time, and the barriers and facilitators to addressing needs. Findings influenced subsequent stages of intervention development. Results: Stakeholders prioritised the need for carers to feel prepared before and during the transition from hospital to home as key to reducing burden. The proposed intervention comprises multiple components based on theoretical methods and practical applications to target relevant determinants. This includes: a training package for information and support providers working with carers; an additional training session for other staff; and elements to support carers to feel prepared. Conclusions: Using Intervention Mapping addressed some of the limitations of previous interventions and fulfilled MRC recommendations by providing a structured framework for systematically incorporating evidence, theories, and stakeholder input throughout intervention development. Further research is required to produce and refine the proposed intervention components before evaluating their effectiveness.

Down’s syndrome is a complex genetic condition arising from trisomy of chromosome 21; it is characterised by alterations in behaviour and synaptic plasticity, leading to deficits in learning and memory. The Tc1 mouse is a transchromosomic mouse model of trisomy-21 which carries a freely segregating and almost complete human chromosome 21. The main aim of this thesis was to explore recognition memory processes in the Tc1 mouse model of trisomy-21. The initial goal was to provide insight into the learning and memory changes associated with triplication of genes on human chromosome 21 in mice. The Tc1 mouse had previously been shown to display a deficit in object recognition memory following a delay of 10-min, but not following a 24-h delay. This thesis aimed to confirm and extend these findings, by testing Tc1 mice on an array of novelty based recognition tasks. This thesis also aimed to explore some of the biological systems underpinning the pattern of learning and memory changes demonstrated by the Tc1 mouse. The expression of c- fos was used as a marker of neuronal activity, allowing for the assessment of regional activity, and in addition, the expression profile of the GluR1 subunit of the AMPA receptor and the GluK1 and GluK5 subunits of the Kainate receptor were examined. Finally, this thesis investigated the impact of the administration of a novel AMPAkine, drug 9A, on the cognitive phenotype of the Tc1 mouse. The behavioural and biochemical analyses provided evidence that the Tc1 mouse model showed a selective deficit in short-term recognition memory while sparing longterm memory for the same type of information, and that a near complete copy of human chromosome 21 in Tc1 mice did not impair place recognition. In addition, c-fos expression studies provided evidence for aberrant perirhinal cortex activity in response to familiarity. Further to this, there was a significant reduction in expression of the GluR1 AMPA receptor subunit in the hippocampus, and a significant reduction of the GluK5 kainate receptor subunit expression in the perirhinal cortex. Finally, this thesis provides some preliminary evidence that a novel positive allosteric modulator, drug 9a, had a positive cognitive enhancing effect in the Tc1 mouse.

Cancer and its treatment are frequently complicated by the development of venous thromboembolism (VTE). Interestingly, VTE incidence rates vary according to tumour type and the chemotherapy regimen administered. Yet, the precise mechanisms responsible for the increase in VTE in cancer patients remain unclear. Tissue factor (TF), the primary cellular initiator of the coagulation cascade, is over-expressed in many solid malignancies, particularly pancreatic cancer, and the number of circulating TF+ microparticles (MP) are increased in cancer patients. It is hypothesised that the increased risk of VTE in cancer patients generated by cytotoxic treatment may be partly attributed to the apoptotic process, involving the exposure of procoagulant phosphatidylserine (PS) on tumour cells or other chemotherapy damaged cells and increased release of TF+ MP into the circulation. The aim of this study was to explore how coagulation can be initiated in cancer cells and be potentiated by chemotherapy, with respects to the specific expression of TF and PS, and generation of MP. Flow cytometry was used to evaluate expression of cell surface TF and level of apoptosis in untreated/doxorubicin (Dox)-treated cancer cell lines, and number of MP in platelet-free plasma (PFP) from untreated pancreatic cancer patients, myeloproliferative disorder (MPD) patients, and multiple myeloma (MM) patients before, during, and after chemotherapy. The cell proliferation of untreated/Dox-treated cancer cells was assessed by an MTS assay. Procoagulant activity (PCA) of untreated/Dox-treated cancer cells and their isolated cell-free supernatants containing MP, and also MM and MPD patient PFP was measured using a prothrombin time assay. Enzyme-linked immunosorbent assay quantified levels of TF in unfiltered/0.1 μm filtered cell-free supernatants isolated from cancer cell lines, and serum levels of soluble cell adhesion molecules CD106 and CD54 from MM patients. Pancreatic (AsPC-1, CFPAC-1, MIA-PaCa-2), ovarian (A270, ES2, SKOV-3), colorectal (CaCo-2, LoVo), breast (MCF-7, MDA-MB-231, T47D), and haematological (JJN3, U937) cancer cells were found to support coagulation in a cell number-dependent manner, defined by a logarithmic relationship that was consistent across all cell lines. Furthermore, single cell clotting time (CT) was determined for each cancer cell line from the slope and y axis intercept of a logarithmically transformed data plot. A near linear relationship was observed between TF expression and single cell CT where a higher expression of TF results in a proportionally faster CT (P = 0.01). In addition, tumour cell-derived MP were shown to be procoagulant and the majority of procoagulant potential could be removed by passing isolated cell-free supernatants through a 0.1 μm filter. A dose-dependent CT was observed with AsPC-1, CFPAC-1, ES2, SKOV-3, LoVo, and MDA-MB-231 cell-free supernatants. The cytotoxic chemotherapeutic agent Dox was found to decrease the number of viable ovarian (ES2), breast (MDA-MB-231, T47D), and haematological (MM.1S, U937) cancer cells in a time- and dose-dependent manner, and cell death was shown to be induced by apoptosis and subsequently necrosis at higher drug concentrations. Cell surface expression of PS was found to increase following Dox treatment, while TF was not upregulated. Furthermore, Dox was shown to dose-dependently increase PCA in all cancer cells examined, although the effect of cell-free supernatants on PCA was less consistent; ES2, MDA-MB-231, and U937 cell-free supernatants isolated from Dox-treated cells demonstrated increased PCA at 0.01 and 0.1 μM concentrations. The Dox-induced increase in PCA of cancer cells and cell-free supernatants were found to correlate with tumour cell viability (r = 0.79 to 0.97, P < 0.01). Numbers of TF+ MP were significantly higher in 35 untreated pancreatic cancer patients in comparison with 15 MM patients prior to chemotherapy (P < 0.0005). Furthermore, numbers of endothelial cell-derived MP (EMP), monocyte-derived MP, plasma cell-derived MP, and PS+ MP, were significantly higher in 6 MPD patients in comparison with 15 MM patients prior to chemotherapy (P < 0.005), but not levels of platelet-derived MP (PMP) or TF+ MP. Markers of endothelial dysfunction, including EMP and soluble cell adhesion molecules CD106 and CD54, were elevated after thalidomide (Thal)- or lenalidomide (Len)-based therapies in MM patients. Furthermore, PCA was significantly increased in MM patients after treatment (P = 0.007), and also levels of PMP, plasma cell-derived MP, and PS+ MP (P < 0.05), but not monocyte-derived MP (P = 0.33) and TF+ MP (P = 0.41). In summary, this study shows that across a range of tumour sites a consistent relationship is seen between procoagulant potential and both cell number and TF cell surface expression. Dox can increase PCA of cancer cells through reduced cell viability that leads to PS exposure. Importantly, this Dox-induced procoagulant mechanism was not found to involve an upregulation of surface TF antigen on ovarian, breast, or haematological cancer cells. In MM patients treated with Thal- or Len-based therapies increased PCA was observed, which may be mediated by endothelial dysfunction and increased generation of MP.

A female advantage is observed in the accurate recognition of mental and emotional states from the face (Hall, 1978, 1984). The psychological mechanisms that may underlie this advantage have not been addressed systematically by researchers. The present thesis discusses the potential mechanisms underlying the female advantage by considering the Extreme Male Brain (EMB) hypothesis of autism (Baron-Cohen, 2002). Several possible directions for research are presented, including sex differences in i) automaticity of processing facial expressions; ii) attention to the eyes; iii) configural versus featural processing of faces; and iv) stimulation of emotion. The first three of these directions are addressed in experimental chapters. A priming task and emotional face-word Stroop task were used to investigate sex differences in the automaticity of processing facial expressions. Sex differences in attention to the eyes were investigated in two eye tracking studies, and in two studies manipulating the eye region of emotional faces. Finally, a study with spatial frequency filtered emotional faces examined sex differences in the use of fine and coarse detail facial information. Overall, the investigations provide some evidence for greater female attention to the eye region in faces, and the possibility that this may explain an observed female advantage in facial expression recognition. Results are discussed in relation to the EMB hypothesis and sex differences in social cognition more generally. Potential directions for further research are outlined.