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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.
21

Bridging inflammatory bowel diseases and hepatobiliary disorders through pathway enrichment and module-based approach

Saloum, Alaa January 2020 (has links)
Inflammatory bowel diseases (IBD) including Crohn’s disease (CD) and ulcerative colitis (UC) are associated with various hepatobiliary disorders. Two of the chronic hepatobiliary disorders that may coexist with inflammatory bowel diseases are: primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). Previous studies have hypothesized that IBD, PBC, and PSC might share an underlying mechanism which contributes to the pathogenesis of the three conditions. In this study, a module-based network analysis and pathway enrichment analysis was applied on IBD, PSC, and PBC differentially expressed genes (DEGs). The sample data were obtained from the study by Ostrowski et al. (2019). A network module-based approach was applied to examine generated results where additional information about biological processes, pathways and molecular functions can be inferred. FunRich and Enrichr were utilized as functional enrichment tools. A protein interaction network was constructed for the three conditions using STRING. Functional modules and overlapping modules of IBD, PSC, and PBC were identified using different plug-ins in Cytoscape. Some of the results were consistent with the findings of Ostrowski et al. (2019) such as the ATP synthesis and signal transduction that is shared among the overlapping genes in IBD, PBC, and PSC. ModuLand highlighted nodes that have been previously reported to have a role in the pathogenesis of autoimmune diseases. The proposed approach demonstrated that the module-based approach contributes to similar results regarding biological processes and pathway enrichment of generated modules, compared to enrichment analysis of DEGs. In addition, the utilization of the ModuLand plug-in to find hierarchal layers of disease genes is still poorly researched and would benefit from more in-depth comparison with related tools for module discovery. For instance, implementing ModuLand plug-in can potentially support research in elucidating complex diseases.
22

Conquering Chemical Space : Optimization of Docking Libraries through Interconnected Molecular Features

Sparring, Leonard January 2020 (has links)
Copied selected text to selection primary: The development of new pharmaceuticals is a long and ardous process that typically requires more than 10 years from target identification to approved drug. This process often relies on high throughput screening of molecular libraries. However, this is a costly and time-intensive approach and the selection of molecules to screen is not obvious, especially in relation to the size of chemical space, which has been estimated to consist of 10 60 compounds. To accelerate this exploration, molecules can be obtained from virtual chemical libraries and tested in-silico using molecular docking. Still, such methods are incapable of handling the increasingly colossal virtual libraries, currently reaching into the billions. As the libraries continue to expand, a pre-selection of compounds will be necessitated to allow accurate docking-predictions. This project aims to investigate whether the search for ligands in vast molecular libraries can be made more efficient with the aid of classifiers extended with the conformal prediction framework. This is also explored in conjunction with a fragment based approach, where information from smaller molecules are used to predict larger, lead-like molecules. The methods in this project are retrospectively tested with two clinically relevant G protein-coupled receptor targets, A 2A and D 2 . Both of these targets are involved in devastating disease, including Parkinson’s disease and cancer. The framework developed in this project has the capacity to reduce a chemical library of > 170 million tenfold, while retaining the 80 % of molecules scoring among the top 1 % of the entire library. Furthermore, it is also capable of finding known ligands. This will allow for reduction of ultra-large chemical libraries to manageable sizes, and will allow increased sampling of selected molecules. Moreover, the framework can be used as a modular extension on top of almost any classifier. The fragment-based approaches that were tested in this project performed unreliably and will be explored further.
23

Quality assessment of protein models

Ray, Arjun January 2012 (has links)
Proteins are crucial for all living organisms and they are involved in many different processes. The function of a protein is tightly coupled to its structure, yet to determine the structure experimentally is both non-trivial and expensive. Computational methods that are able to predict the structure are often the only possibility to obtain structural information for a particular protein. Structure prediction has come a long way since its inception. More advanced algorithms, refined mathematics and statistical analysis and use of machine learning techniques have improved this field considerably. Making a large number of protein models is relatively fast. The process of identifying and separating correct from less correct models, from a large set of plausible models, is also known as model quality assessment. Critical Assessment of Techniques for Protein Structure Prediction (CASP) is an international experiment to assess the various methods for structure prediction of proteins. CASP has shown the improvements of these different methods in model quality assessment, structure prediction as well as better model building. In the two studies done in this thesis, I have improved the model quality assessment part of this structure prediction problem for globular proteins, as well as trained the first such method dedicated towards membrane proteins. The work has resulted in a much-improved version of our previous model quality assessment program ProQ, and in addition I have also developed the first model quality assessment program specifically tailored for membrane proteins. / <p>QC 20120313</p>
24

Improving SARS-CoV-2 analyses from wastewater

Dafalla, Israa Yahia Al Hag Ibrahim January 2021 (has links)
Wastewater-based epidemiology (WBE) analyzes wastewater for the presence of biological and chemical substances to make public health conclusions. COVID-19 disease is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) that infected individuals shed also in their feces, making WBE an alternative way to track SARS-CoV-2 in populations. There are many limitations to the detection and quantification of SARS-CoV-2 from wastewater, such as sample quality, storage conditions or viral concentration. This thesis aims to determine the extent of these limitations and the factors that contribute to them. Other viruses can help the measurements for example Bovine coronavirus (BCoV) can be spiked as a process surrogate, while Pepper mild mottle virus (PMMoV), a fecal biomarker is used to estimate the prevalence of SARS-CoV-2 infection. This study involved two distinct wastewater samples. For method comparison both samples were processed with two methods: virus concentration by electronegative (EN) filtration or direct RNA extraction method. From the RNA extracts RT-qPCR assays were performed to identify and quantify SARS-CoV-2, BCoV, and PMMoV. Based on the obtained cycle threshold (Ct) values, viral gene copy numbers and virus concentration of the original wastewater samples were calculated. Statistical tests were conducted to assess suggested hypothesizes and variations within the data. Results revealed differences in viral contents due to different sample qualities and as a result of freezing and thawing. Furthermore, different sample processing methods led to differences in quantification. In conclusion, improving analysis of SARS-CoV-2 in wastewater using methodologies with better detection efficiency leads to more reliable results.
25

Sepsis-associated Escherichia coli whole-genome sequencing analysis using in-house developed pipeline and 1928 diagnostics tool

Lember, Geivi January 2021 (has links)
Sepsis is a life-threatening condition that is caused by a dysregulated host response to infection. Timely detection of sepsis and antibiotic treatment is important for the patient’s recovery from sepsis. Usually, when sepsis is detected, immediate antibiotic treatment is started with broad-spectrum antibiotics as it takes time to determine the correct antibiotic susceptibility. To overcome this problem, next-generation sequencing is seen as one possible development in clinical diagnostics in the future. Automated bioinformatics pipelines could be used initially for surveillance purposes but eventually for rapid clinical diagnosis. Therefore, the results of 1928 Diagnostics, an automated pipeline for whole-genome sequencing (WGS) data analysis, were compared with the results of an in-house developed pipeline for manual data processing by analyzing sepsis-associated Escherichia coli (SEPEC) WGS data. The pipelines were compared by assessing their predicted antimicrobial resistance (AMR) genes, virulence genes and epidemiological relatedness. In addition, the predicted resistance genes were compared to phenotypic antimicrobial susceptibility testing (AST) data from the clinical microbiology laboratory. All the results obtained from the 1928 Diagnostics and in-house pipeline were similar but differed in the number of virulence/predicted AMR genes, AMR gene variants, detection of species and epidemiologically related E. coli samples. Moreover, the predicted AMR genes from both pipelines did not show a good overall relation to the phenotypic AST result. More studies are needed to make predictions of genes from the WGS analysis more reliable so that WGS analysis can be used as a diagnostics tool in clinical laboratories in the future.
26

Optimisation of ForenSeq STR data analysis with FDSTools and comparative analysis with UAS

Thelander, Tilia January 2021 (has links)
DNA profiling with short tandem repeat data generated with massively parallel sequencing is associated with several challenges. FDSTools is an open-source software which applies correction models based on a reference database to correct DNA profiles. The correction models aim to provide an accurate representation of the true DNA profile and associated artefacts. Low analytical thresholds in FDSTools are suggested to improve detection of minor profiles in complex mixtures. The objective was to optimise FDSTools analysis for ForenSeq data, and to establish a Swedish reference database. The FDSTools analysis was subsequently compared to default analysis with the commercial Universal Analysis Software, and the likelihood ratio was evaluated. The FDSTools Library file was adapted for ForenSeq data. FASTQ files from single- and mixed-source samples were analysed with the software. The concordance between the software was assessed, and analytical thresholds in FDSTools were optimised. Likelihood ratios were calculated for sequencing- and capillary electrophoresis data to investigate the benefit of sequence level information. A reference database and correction models could not be generated, meaning that uncorrected data was used. The two software showed a 98.5% concordance. Disconcordance was caused by allele drop-out in heterozygous loci which implicated that certain markers may require individual interpretation. Lowering the analytical thresholds in FDSTools appeared to improve mixture deconvolution, but the lack of correction models obscured interpretation. Hence, without correction models optimial analytical thresholds could not be defined. Likelihood ratio based on sequencing data was not consistently higher compared to capillary electrophoresis, suggesting that sequence information is not always advantageous.
27

Development and evaluation of a cost-effectiveness analysis model for sepsis diagnosis

Alborgeba, Zainab January 2020 (has links)
Sepsis is a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Sepsis is a substantial health care and economic burden worldwide and is one of the most common reasons for admission to the hospital and intensive care unit. Early diagnosis and targeted treatment of sepsis are the bases to reduce the mortality and morbidity. Conventional blood culturing is the gold standard method for sepsis diagnostics. However, blood culturing is a time consuming method, requiring at least 48 to 72 hours to get the first results with very low sensitivity and specificity. The aim of this study was to determine and assess the direct sepsis-related costs for PCR-based diagnostic strategies (SeptiFast and POC/LAB). A mathematical model was constructed to compare PCR-based diagnostic strategies with the conventional blood culturing. Three case scenarios were investigated based on data from the United Kingdom, Spain and the Czech Republic. It was found that, POC/LAB was the most cost effective strategy in all countries if it could reduce the hospitalization length of stay with at least 3 days in the normal hospital ward and 1 day in the intensive care unit. Reducing the hospitalization length of stay had the greatest impact on the economic outcomes. While, reducing the costs of the diagnostic strategies did not show a remarkable effect on the economic results. In conclusion, the findings suggest that PCR-rapid diagnostic methods could be cost-effective for the diagnosis of patients with sepsis if they could reduce the hospitalization length of stay.
28

Optimering av Pairwise Comparative Modelling för prediktion av antimikrobiella resistensdeterminanter i mikrobiomdata från människa / Optimization of Pairwise Comparative Modelling for the prediction of antimicrobial resistance determinants in human derived microbiome data

Moretti, Gianluca January 2021 (has links)
The increasing spread of antibiotic resistance among microorganisms is a dangerous threat for human health. It is therefore necessary to have appropriate tools to understand the phenomenon and monitor its development. Metagenomics has been shown to be a powerful approach for this purpose, with its capability to capture the complexity of the genetic fingerprint of virtually all microorganisms present in an environment, without the bias of the cultivation in laboratory conditions. Pairwise Comparative Modeling (PCM) is a software for prediction of antimicrobial resistance (AMR) from metagenomic samples that has been shown to outperform other tools due to its structure-based alignmentapproach. However, this comes with a higher computational cost. Therefore, the aim of this project was to optimize the allocation of computational resources for the different processes used by the software and to explore different hyperparameters configurations. A new version of the software was developed to enable a more flexible allocation of computational resources and a better portability in different computational environments. Different settings of the hyperparameters were explored and a configuration was found that reduced the CPU hours required to complete the execution of the pipeline by 65.2% compared to default settings, without affecting the sensitivity of the prediction.These results could facilitate the utilization of PCM and its applicability to different contexts, promotingsurveillance programs and research in the field of AMR.
29

Study of up-regulated genes in gene clusters during formation of mature hepatocytes from human induced pluripotent stem cells to identify transcription factors and mirnas

Alexander, Suraj Thomas January 2021 (has links)
The multifunctional purpose of hepatocytes, the functional liver cells within the metabolic, endocrine and secretory functions highlights key importance in emphasizing the research and treatment methods that utilize these cells. Forming 80% of the liver's cells, hepatocytes are involved in many of the primary functions of the liver including the delivery of immune response against pathogens and aiding in the detoxification of drugs. As a result, it provides a valuable basis for medical research. Through the findings of Ghosheh et al. (2017), a method of generating mature hepatocytes was achieved through the human pluripotent stem cells (HPSC), but the generation of hepatocytes in which all the genes are expressed at the right amount through this method proves to be a difficult endeavor. The primary goal of this project is to utilize the established findings to enhance and improve the efficacy of the process that goes behind the generation of mature hepatocytes. The approach towards the current project was initiated with culturing and differentiating three human embryonic stem cell lines and three human-induced pluripotent stem cell lines into mature hepatocytes. In the study mentioned, k-means clustering along with Pearson correlation as the distant measure was run in R to subdivide the top 2000 genes with the highest differential expression into 10 clusters. The cluster data from this paper was used to do the current study, in which the up-regulated and down-regulated gene were first identified for clusters 2, 4 &amp; 6 and 9. The interactions of up-regulated genes in these clusters were further analyzed using Enrichr to identify the different miRNAs for various genes from the clusters. Within cluster 2, a total of 8 genes showed the possibility of being regulated using 4 miRNAs. Transcription factors were also identified for cluster 2 and a combination of HNF1A, EP300, AHR, NFKB1 and HIF1A could repress 8 genes that were not repressed by miRNAs. In cluster 4 &amp; 6, most of the up-regulated genes showcased tumorigenicity and all 20 genes identified could be regulated with the combination of 7 miRNAs. In cluster 9, a combination of 11 miRNAscould be used to regulate 26 out of 27 genes that were analyzed. Ensuring that stem cell products do not turn cancerous is a priority in the medical field. Conducting the analyses of the other clusters aside from 2, 4 &amp; 6 and 9 will prove highly beneficial in reducing the risks pertaining to stem cell mutation due to overexpression of genes.
30

An assessment of the surrogate host metagenome-assembled genome decontamination for non-model host organisms : Proof-of-concept

Bourbonnais, André January 2023 (has links)
In this study, a novel method has been assessed to bridge the gap between bioinformatics and ecological conservation efforts to gain evidence to further base conservational plans on. Herein, the validity of using a provisional host metagenome-assembled metagenome to decontaminate the data from host contamination was concluded. To achieve this, 11 samples of increasing host contamination were devised by simulating reads from 100 genomes representing Platanthera bifolia and Platanthera chlorantha endophytic root microbiomes. By following the Critical Interpretation of Metagenome Interpretation benchmarking framework, the method was evaluated on assembly and binning performance. The study concluded strong negative correlations with host contamination that is derived by the lowered proportion of endophytic sequence depth at the higher host contamination levels. Furthermore, statistically significant difference between the control and the perfect GHOST-MAGNET was determined when accounting for the proportion of bins being endophytic.

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