6,884 research outputs found

    Investigating the effects of palmitoylation on the dopamine 1 receptor (D1)

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    The dopamine D1 receptor (D1) is a G protein-coupled receptor (GPCR) which regulates various key brain functions like attention, movement, reward, and memory. Understanding D1 signalling may open the horizon for novel treatments for neurological disorders. Upon agonist activation, the heterotrimeric G proteins Gαs activate adenylyl cyclase to increase cAMP/PKA signalling. D1 also engages β-arrestin proteins leading to β-arrestin dependent signalling. The D1 has two palmitoylation sites on cysteines 347&351 in its C-tail domain. However, the distinct roles and implications of palmitoylation on the D1 signalling, trafficking and β-arrestins recruitment are still largely unexplored. A palmitoylation D1 mutant was generated and luminescent based techniques such as BRET and split-Nanoluc complementation assay were employed, to delineate D1 palmitoylation effects on its pharmacology and signalling. The D1 agonists induced 50% less cAMP production in the mutant compared to wildtype (WT) and WT showed a more efficient dissociation of its Gαs. Moreover, the mutant receptor failed to recruit β-arrestin1&2, induced less ERK1/2 activation and internalises in an agonist-independent process while showing an altered intracellular Golgi trafficking. Also, in β-arrestin 1&2 KO HEK 293 cells similar cAMP production levels were reported for D1 WT and palmitoylation mutant. β-arrestin 1&2 KO blocked agonist-induced WT D1 plasma membrane trafficking, indicating that these β-arrestins are driving the differences between WT and the palmitoylation mutant D1. Taken together, our studies indicate that Gαs is the main transducer for D1 cAMP and ERK1/2 signalling and that palmitoylation is essential for its β-arrestin 1&2 interactions and modulating D1 signalling cascades in a drug-dependant process

    Deep Learning Techniques for Electroencephalography Analysis

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    In this thesis we design deep learning techniques for training deep neural networks on electroencephalography (EEG) data and in particular on two problems, namely EEG-based motor imagery decoding and EEG-based affect recognition, addressing challenges associated with them. Regarding the problem of motor imagery (MI) decoding, we first consider the various kinds of domain shifts in the EEG signals, caused by inter-individual differences (e.g. brain anatomy, personality and cognitive profile). These domain shifts render multi-subject training a challenging task and impede robust cross-subject generalization. We build a two-stage model ensemble architecture and propose two objectives to train it, combining the strengths of curriculum learning and collaborative training. Our subject-independent experiments on the large datasets of Physionet and OpenBMI, verify the effectiveness of our approach. Next, we explore the utilization of the spatial covariance of EEG signals through alignment techniques, with the goal of learning domain-invariant representations. We introduce a Riemannian framework that concurrently performs covariance-based signal alignment and data augmentation, while training a convolutional neural network (CNN) on EEG time-series. Experiments on the BCI IV-2a dataset show that our method performs superiorly over traditional alignment, by inducing regularization to the weights of the CNN. We also study the problem of EEG-based affect recognition, inspired by works suggesting that emotions can be expressed in relative terms, i.e. through ordinal comparisons between different affective state levels. We propose treating data samples in a pairwise manner to infer the ordinal relation between their corresponding affective state labels, as an auxiliary training objective. We incorporate our objective in a deep network architecture which we jointly train on the tasks of sample-wise classification and pairwise ordinal ranking. We evaluate our method on the affective datasets of DEAP and SEED and obtain performance improvements over deep networks trained without the additional ranking objective

    Defining novel regulators of inflammatory signalling in pancreatic cancer

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    Pancreatic ductal adenocarcinoma (PDAC) remains a cancer with few effective therapeutic options and, for patients with this disease, the prognosis remains extremely poor. In recent years immunotherapy has emerged as a promising treatment modality for a number of different tumour types but so far its impact in treatment of PDAC has been limited. Examining the molecular pathways that determine the immune response to cancer cells in PDAC will enable development of new therapeutic strategies to target this response. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is elevated in human PDAC tissues and correlates with high levels of fibrosis and poor CD8+ T cell infiltration. The Serrels Laboratory has already demonstrated a role for FAK in promoting tumour evasion by inducing an immunosuppressive microenvironment, specifically by regulation of cytokines. This has led to trials of the FAK inhibitor (defactinib) in conjunction with immunotherapy. I proposed that FAK was likely to regulate further chemokine/cytokine and ligand receptor networks and that by understanding more about these networks it may be possible to target potential pathways to modify this response and provide therapeutic benefit. I used CRISPR, Forward Phase Protein Arrays (FPPA) and ELISA on mouse and human PDAC cell lines to examine relative expression of chemokines and cytokines and how this expression was regulated by FAK. I identified CXCL16 as one of the most abundantly expressed cytokines in both mouse and human cell lines and one of the most significantly increased cytokines upon FAK depletion. PDAC FAK null cell lines +/- CXCL16 were then orthotopically implanted into the pancreas of C57BL/6 mice and I demonstrated that CXCL16 depletion resulted in a re-programming of the immune cell tumour infiltrate with reduced tumour growth. These findings identify a FAK dependent CXCL16-CXCR6 paracrine signalling axis that may represent a mechanism of resistance to FAK inhibition and thus an important potential therapeutic target

    Endoplasmic reticulum localization of phosphoinositide specific phospholipase C enzymes in U73122 cultured human osteoblasts

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    Different signal transduction pathways contribute to the differentiation and metabolic activities of osteoblasts, with special regard to the calcium-related pathway of phosphoinositide specific phospholipase C (PLC) enzyme family. PLC enzymes were demonstrated to be involved in the differentiation of osteoblasts and differently localize in the nucleus, cytoplasm or both depending on the isoform. The amino-steroid molecule U-73122 inhibits the enzymes belonging to the PLC family. In addition to the temporary block of the enzymatic activity, U-73122 promotes off-target effects, including modulation of the expression of selected PLC genes and different localization of PLC enzymes, depending on the cell line, in different cell lines. In order to evaluate possible off-target effects of the molecule in human osteoblasts, we investigated the expression of PLC genes and the localization of PLC enzymes in cultured human osteoblasts (hOBs) in the presence of low dose U-73122. Our results confirm that all PLC genes are transcribed in hOBs, that probably splicing variants of selected PLC genes are expressed and that all PLC enzymes are present in hOBs, except for PLC δ3 in quiescent hOBs at seeding. Our results confirm literature data excluding toxicity of U-73122 on cell survival. Our results indicate that U-73122 did not significantly affect the transcription of PLC genes. It acts upon the localization of PLC enzymes, as PLC enzymes are detected in cell protrusions or pseudopodia-like structures, at the nuclear or the plasma membrane, in membrane ruffles and/or in the endoplasmic reticulum

    Investigating the early interaction between Mycobacterium avium ssp paratuberculosis and the host using a bovine enteroid system

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    Mycobacterium avium ssp paratuberculosis (MAP) is the causative agent of Johne’s disease (JD), a chronic granulomatous enteritis of ruminant’s prevalent world-wide. Infection of calves occurs through the faecal oral route, typically in animals <6 months old. Animals are asymptomatic for 2-5 years before clinical signs begin to show, which typically present as emaciation and chronic diarrhoea. In the subclinical phase, animals will have decreased milk yield, increased susceptibility to other diseases and decreased feed conversion. This has a severe impact on the farming economy and animal welfare, as affected animals are often prematurely culled. Infected subclinical animals are extremely difficult to identify but can still act as a source of transmission for the rest of the herd by shedding MAP in their faeces. There is no treatment for JD, and the current diagnostic tests are ineffective. By investigating the initial interaction between MAP and the host at the intestinal lining, a greater understanding of MAP pathogenesis can be gained and better diagnostic and therapeutic targets can be identified. In this work, proteins expressed on the surface of MAP were assessed for their ability to aid attachment, invasion and intracellular survival in epithelial and phagocytic cells when expressed on the membrane of a non-invasive E. coli host strain. The proteins investigated were encoded by mammalian cell entry (mce) genes, mce1A, mce1D, mce3C and mce4A, which have been implicated in attachment and invasion of epithelial cells by other mycobacteria. Interestingly, E. coli expressing Mce1A had enhanced uptake by phagocytic cells and E. coli expressing Mce1D had enhanced attachment and invasion of epithelial cells, but neither protein conferred this phenotype in both eukaryotic cell types investigated. To identify key intestinal cell types involved in MAP pathogenesis, bovine intestinal organoids (enteroids) were assessed for their ability to model a MAP infection in a physiologically representative system. Baso-out 3D enteroids, apical-out 3D enteroids and 2D monolayers were created, and the cell types present were compared to bovine intestinal tissue samples using RT-PCR and immunofluorescence microscopy. The models contained the mature epithelial cell types of the intestine including goblet cells, enteroendocrine cells, Paneth cells and enterocytes. 3D baso-out enteroids and 2D monolayers also contained proliferative cells, but the 3D apical-out enteroids did not and so could not be maintained past 2 weeks of culture. The models were infected with two strains of MAP over the course of 72 hours, the reference strain K10, and a recent clinical isolate C49. MAP C49 was shown to be present in all three intestinal models in consistently higher numbers than MAP K10, quantified using qPCR of the genomic DNA. This indicates that MAP C49 was better able to infect these models than K10, which may suggest a loss of virulence in MAP K10. Overall, the data presented has increased our understanding of MAP pathogenesis by emphasising the need for multicellular models which accurately represent the pathogen target cell type/s in vivo and the confirmation of the role of two hypothetical MAP proteins in cellular interactions

    Introduction to Psychology

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    Introduction to Psychology is a modified version of Psychology 2e - OpenStax

    Undergraduate Catalog of Studies, 2022-2023

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    Quality of experience and access network traffic management of HTTP adaptive video streaming

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    The thesis focuses on Quality of Experience (QoE) of HTTP adaptive video streaming (HAS) and traffic management in access networks to improve the QoE of HAS. First, the QoE impact of adaptation parameters and time on layer was investigated with subjective crowdsourcing studies. The results were used to compute a QoE-optimal adaptation strategy for given video and network conditions. This allows video service providers to develop and benchmark improved adaptation logics for HAS. Furthermore, the thesis investigated concepts to monitor video QoE on application and network layer, which can be used by network providers in the QoE-aware traffic management cycle. Moreover, an analytic and simulative performance evaluation of QoE-aware traffic management on a bottleneck link was conducted. Finally, the thesis investigated socially-aware traffic management for HAS via Wi-Fi offloading of mobile HAS flows. A model for the distribution of public Wi-Fi hotspots and a platform for socially-aware traffic management on private home routers was presented. A simulative performance evaluation investigated the impact of Wi-Fi offloading on the QoE and energy consumption of mobile HAS.Die Doktorarbeit beschäftigt sich mit Quality of Experience (QoE) – der subjektiv empfundenen Dienstgüte – von adaptivem HTTP Videostreaming (HAS) und mit Verkehrsmanagement, das in Zugangsnetzwerken eingesetzt werden kann, um die QoE des adaptiven Videostreamings zu verbessern. Zuerst wurde der Einfluss von Adaptionsparameters und der Zeit pro Qualitätsstufe auf die QoE von adaptivem Videostreaming mittels subjektiver Crowdsourcingstudien untersucht. Die Ergebnisse wurden benutzt, um die QoE-optimale Adaptionsstrategie für gegebene Videos und Netzwerkbedingungen zu berechnen. Dies ermöglicht Dienstanbietern von Videostreaming verbesserte Adaptionsstrategien für adaptives Videostreaming zu entwerfen und zu benchmarken. Weiterhin untersuchte die Arbeit Konzepte zum Überwachen von QoE von Videostreaming in der Applikation und im Netzwerk, die von Netzwerkbetreibern im Kreislauf des QoE-bewussten Verkehrsmanagements eingesetzt werden können. Außerdem wurde eine analytische und simulative Leistungsbewertung von QoE-bewusstem Verkehrsmanagement auf einer Engpassverbindung durchgeführt. Schließlich untersuchte diese Arbeit sozialbewusstes Verkehrsmanagement für adaptives Videostreaming mittels WLAN Offloading, also dem Auslagern von mobilen Videoflüssen über WLAN Netzwerke. Es wurde ein Modell für die Verteilung von öffentlichen WLAN Zugangspunkte und eine Plattform für sozialbewusstes Verkehrsmanagement auf privaten, häuslichen WLAN Routern vorgestellt. Abschließend untersuchte eine simulative Leistungsbewertung den Einfluss von WLAN Offloading auf die QoE und den Energieverbrauch von mobilem adaptivem Videostreaming

    Studying the interplay between ageing and Parkinson's disease using the zebrafish model

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    Parkinson’s disease (PD) is a neurodegenerative disorder characterised by the loss of dopaminergic neurons in the substantia nigra. Ageing is the major risk factor for developing PD but the interplay between ageing and PD remains elusive. To investigate the effect of ageing on PD-relevant pathological mechanisms, zebrafish mutant lines harbouring mutations in ageing-associated genes (klotho-/-, sirt1-/-, satb1a-/-, satb1b-/- and satb1a-/-;satb1b-/-) were generated, using CRISPR/Cas9 gene editing. Likewise, a chemical model for SIRT1 deficiency was utilised. klotho-/- zebrafish displayed an accelerated ageing phenotype at 3mpf and reduced survival to 6mpf. Dopaminergic neuron number, MPP+ susceptibility and microglial number were unaffected in klotho-/- larvae. NAD+ levels were decreased in 6mpf klotho-/- brains. However, ATP levels and DNA damage were unaffected. sirt1-/- zebrafish did not display a phenotype through adulthood. il-1β and il-6 were not upregulated in sirt1-/- larvae, and chemical inhibition of sirt1 did not increase microglial number. cdkn1a, il-1β and il-6 were not upregulated in satb1a-/- and satb1b-/- larvae. Dopaminergic neuron number and MPP+ susceptibility were unaffected in satb1a-/- larvae. However, satb1b-/- larvae demonstrated a moderate decrease in dopaminergic neuron number but equal susceptibility to MPP+ as satb1b+/+ larvae. Adult satb1a-/- but not adult satb1b-/- zebrafish were emaciated. satb1a-/-;satb1b-/- zebrafish did not display a phenotype through adulthood. Transgenic zebrafish expressing human wildtype α-Synuclein (Tg(eno2:hsa.SNCA-ires-EGFP)) were crossed with klotho-/- and sirt1-/- zebrafish, and treated with a sirt1-specific inhibitor. Neither genetic cross affected survival. The klotho mutation did not increase microglial number in Tg(eno2:hsa.SNCA-ires-EGFP) larvae. Likewise, sirt1 inhibition did not induce motor impairment or cell death in Tg(eno2:hsa.SNCA-ires-EGFP) larvae. In conclusion, the suitability of zebrafish for studying ageing remains elusive, as only 1 ageing-associated mutant line displayed accelerated ageing. However, zebrafish remain an effective model for studying PD-relevant pathological mechanisms due to the availability of CRISPR/Cas9 gene editing, neuropathological and neurobehavioral tools
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