Skip directly to content

Coming dissertations at MedFak

  • Studies of drug safety in the treatment of rheumatoid arthritis Author: Johanna Karlsson Sundbaum Link: Publication date: 2020-05-04 14:17

    Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting mainly smaller joints. Patients are at risk for complications as joint destruction, but starting treatment soon after onset of disease, has reduced the risk for complications. Methotrexate (MTX) is the anchor drug in the treatment of RA and has proven effects on both inflammatory symptoms and joint destruction. apy. Identifying patients at risk for MTX-induced hepatotoxicity before treatment could be a way to minimize the risk for Adverese effects.Following the introduction of pre-treatment screening, the risk of tuberculosis (TB) among patients with RA starting biologic treatment has decreased. By contrast, the risk remains several-fold increased in RA patients non-exposed to biological treatment. Knowledge about risk factors for TB and TB characteristics in this group of patients, and thus optimal clinical risk stratification and preven-tion, is still limited.In Paper I, only a small number of ALT tests (7%) performed during MTX therapy in RA patients, capture an elevation of ALT > upper limit of normal (ULN). ALT >1.5 × ULN was observed in 44 (21%) patients and the strongest predictor was a pre-treatment elevation of ALT. Recurrent elevations occurred in 70% of patients who continued treatment, and the proportion was similar in those with and without interventions. The results support a more individualized approach to monitoring and handling of ALT elevations during MTX therapy. In Paper II MTHFR A1298C (rs1801131) was nominally associated with ALT >1.5 x ULN within 6 months after the start of MTX (OR=1.7 [95% CI 1.04-2.9], p=0.03). In a multi-ple regression analysis for ALT >1.5 X ULN within 6 months of treatment start, including known risk factors for ALT elevation and MTHFR A1298C, the C-statistic was 0.734. A mod-el containing clinical risk factors and MTHFR A1298C might be used for prediction of ALT elevation in MTX treated patients. In Paper III a Genome-Wide Association Study (GWAS) and analysis of candidate Single Nucleotide Polymorphisms (SNPs) were performed. Four SNPs in and upstream of the ribonucleoprotein, PTB Binding 2 gene on chromosome 1 were associated with max ALT within 6 months on a genome wide level (p<5x10-8). Our results indicate that the RAVER2 and/or JAK1 genes might play a role in MTX- induced hepatotoxici-ty, but further studies are necessary for confirmation of the results. In Paper IV, we performed a population based case-control study. Several RA-associated risk factors (treatment with leflunomide, azathioprine or prednisolone and concomitant obstructive lung disease) may contribute to the increased TB risk in biologics-naïve RA patients. We could not confirm previous findings of an association with the use of moderate to high doses of prednisolone (≥15 mg). TB risk seems difficult to predict with precision in the individual biologics-naïve patient based on RA-associated risk factors. This suggests TB screening should be considered in biologics-naïve patients.

    In conclusion, results from these studies suggest that several factors could increase the risk of AEs in RA patients. The risk might be reduced by utilizing prediction models that include knowledge about the medical history of the individual patient and genetic data in combination with screening for TB.

  • Membrane-bound proteins : Characterization, evolution, and functional analysis Author: Misty M. Attwood Link: Publication date: 2020-05-04 09:36

    Alpha-helical transmembrane proteins are important components of many essential cell processes including signal transduction, transport of molecules across membranes, protein and membrane trafficking, and structural and adhesion activities, amongst others. Their involvement in critical networks makes them the focus of interest in investigating disease pathways, as candidate drug targets, and in evolutionary analyses to identify homologous protein families and possible functional activities. Transmembrane (TM) proteins can be categorized into major groups based the same gross structure, i.e., the number of transmembrane helices, which are often correlated with specific functional activities, for example as receptors or transporters. The focus of this thesis was to analyze the evolution of the membrane proteome from the last holozoan common ancestor (LHCA) through metazoans to garner insight into the fundamental functional clusters that underlie metazoan diversity and innovation. Twenty-four eukaryotic proteomes were analyzed, with results showing more than 70% of metazoan transmembrane protein families have a pre-metazoan origin. In concert with that, we characterized the previously unstudied groups of human proteins with three, four, and five membrane-spanning regions (3TM, 4TM, and 5TM) and analyzed their functional activities, involvement in disease pathways, and unique characteristics. Combined, we manually curated and classified nearly 11% of the human transmembrane proteome with these three studies. The 3TM data set included 152 proteins, with nearly 45% that localize specifically to the endoplasmic reticulum (ER), and are involved in membrane biosynthesis and lipid biogenesis, proteins trafficking, catabolic processes, and signal transduction due to the large ionotropic glutamate receptor family. The 373 proteins identified in the 4TM data set are predominantly involved in transport activities, as well as cell communication and adhesion, and function as structural elements. The compact 5TM data set includes 58 proteins that engage in localization and transport activities, such as protein targeting, membrane trafficking, and vesicle transport. Notably, ~60% are identified as cancer prognostic markers that are associated with clinical outcomes of different tumour types. This thesis investigates the evolutionary origins of the human transmembrane proteome, characterizes formerly dark areas of the membrane proteome, and extends the fundamental knowledge of transmembrane proteins.

  • New strategies and tools for Plasmodium falciparum case management and surveillance in the era of imminent resistance to artemisinin-based combination therapy in Tanzania. Author: Lwidiko E Mhamilawa Link: Publication date: 2020-04-29 14:58

    Artemether-lumefantrine has been an efficacious first line treatment for uncomplicated Plasmodium falciparum malaria in Tanzania since its introduction in 2006. Interest has developed in understanding the observation of high residual PCR determined positivity rates on day 3 after supervised artemether-lumefantrine treatment in the magnitude of almost 30% in previous assessments from 2015 in Bagamoyo district, Tanzania. Deep sequencing has recently been used to study these Bagamoyo parasites with delayed clearance, and the clearance times by PCR of some P. falciparum sub-populations were similar to artemisinin resistant parasites in Myanmar as assessed by microscopy, albeit lacking the described mutations in the Kelch13 propeller gene associated with artemisinin resistance. Moreover, molecular epidemiological studies from Bagamoyo, have shown temporal selection of lumefantrine associated genetic tolerance/resistance markers (pfmdr1 - N86, 184F, D1246 and pfcrt - K76) in the parasite population following wide scale use of artemether-lumefantrine but without signs of compromised treatment efficacy. On the other hand, traditional epidemiological studies have reported that imported malaria cases in Zanzibar from Tanzania mainland contribute to regressing the malaria elimination efforts in this pre-elimination part of the country.

    This PhD project explored efficacy and safety of extending the artemether-lumefantrine regimen from standard 3 days to 6 days and adding single low dose primaquine (0.25mg/kg) as a new strategy that can be used in order to protect the therapeutic lifespan of artemether-lumefantrine. Also, whole-genome sequencing was used to study genomic epidemiology of P. falciparum population between Tanzania mainland and Zanzibar.

    The results revealed that extended artemether-lumefantrine treatment did not have superior efficacy in the current context of artemether-lumefantrine sensitive P. falciparum parasites. However, the safety profile was excellent and similar to standard 3 days treatment. Parasite detection by molecular methods was 84% on day 3 after artemether-lumefantrine treatment. Meanwhile, significant decreases in the effective population sizes were inferred in both Tanzania mainland and Zanzibar parasite populations, that coincide with a period of decreasing malaria transmission in Tanzania. The parasite population from Tanzania mainland and Zanzibar were found to be connected, implying importation of cases from high transmission mainland to pre elimination regions of Zanzibar.

    Utility of these results is during exploring options of alternative artemisinin-based combination therapy regimens to protect their therapeutic efficacy in an era of imminent artemisinin resistance in sub Saharan Africa. Moreover, the genomic epidemiological findings in this project may be of interest for malaria elimination programs, in the incorporation of molecular tools in future malaria elimination strategies and resistance surveillance, in the context of understanding importation of malaria from high to low transmission regions.