Coming dissertations at MedFak
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Clinical and Genetic studies in Chronic Myeloid Leukaemia
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-524571
This thesis explores strategies to enhance deep molecular response (DMR) rates and treatment-free remission (TFR) eligibility in chronic myeloid leukaemia (CML), investigates factors linked to treatment milestone failures, describes tyrosine kinase inhibitor (TKI) discontinuation outcomes in a population-based cohort, and examines TFR probabilities after a second TKI discontinuation. In paper I we examined data from the Swedish CML registry on 128 CML patients in chronic phase with a reported TKI discontinuation of ≥1 month due to DMR. Findings indicate that patients discontinuing a 2nd generation TKI had a higher probability of remaining treatment-free, and 11% of patients with a diagnosis of CML in chronic phase were treatment free by last follow-up. Paper II involved a long-term follow-up of 40 patients treated initially with a 2nd generation TKI, dasatinib, combined with a low dose of pegylated interferon α2b as part of the phase II study NordCML007. The combination had an acceptable toxicity profile, and the occurrence of late dasatinib-related adverse events was not increased compared with previous studies of single treatment with dasatinib. The proportion of patients achieving major and DMR were high in comparison with historical cohorts of patients treated with dasatinib. In paper III, an interim analysis was conducted on CML patients attempting a second TKI discontinuation within the DAstop2 study, after a prior molecular relapse. After a median 27 months from the second discontinuation attempt, 50% had re-initiated TKI therapy, and TFR rate after 12 months was 56%. Those with a short (<6 months) TFR duration after the first discontinuation attempt were more likely to experience a molecular relapse after the second discontinuation attempt. Paper IV retrospectively analysed 20 patients newly diagnosed with CML in chronic phase and primary refractory to TKI treatment without BCR::ABL1 kinase domain mutations. Diagnostic samples were analysed for pathogenic variants in a panel of 54 genes recurrently mutated in myeloid neoplasms. Pathogenic variants were seen in 50% with AXL1 being the most frequently affected gene. All patients with truncating ASXL1 variants exhibited resistance to multiple TKIs. Overall, this thesis highlights the potential of TKI discontinuation in selected CML patients, the promising combination of dasatinib and pegylated interferon α in achieving high DMR rates, and the importance of genetic profiling in understanding TKI resistance.
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Role of Fatty Acid Composition in Non-Alcoholic Fatty Liver Disease: a Dietary Perspective : Results from Interventional and Observational Studies
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-524500
The overall aim of this doctoral thesis was to investigate the role of circulating, liver and dietary fatty acids in non-alcoholic fatty liver disease (NAFLD). For circulating and liver fatty acids, special emphasis was given to fatty acids reflecting diet.
In paper I, circulating cholesteryl ester (CE) linoleic acid (18:2n-6), which is considered a good biomarker of dietary intake of 18:2n-6, was cross-sectionally inversely associated with liver fat in n=308 50-year old men and women. Several fatty acids reflecting both exogenous intake and endogenous metabolism were associated with liver fat, basal fat oxidation and resting energy expenditure (REE). No association between fatty acids and liver fat, except for docosahexaenoic acid (22:6n-3) and liver fat, were attenuated after adjusting for REE.
In paper II, phospholipid (PL) 22:6n-3 in liver tissue, a potential biomarker of dietary intake of 22:6n-3, was cross-sectionally inversely associated with liver fibrosis in n=60 men and women with biopsy-verified NAFLD. This finding was not replicated in plasma. Several other fatty acids reflecting both exogenous intake and endogenous metabolism were associated with fibrosis. Pooled saturated fatty acids (SFA) were generally positively associated whereas monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) were inversely associated with fibrosis.
In paper III, no clear (i.e. imprecise) associations were observed for any of the nutrient or food substitutions with incidence NAFLD cirrhosis or hepatocellular carcinoma (HCC), over a median follow-up of 24 years in n>77 000 middle-aged to elderly men and women.
In paper IV, a 12-month randomized controlled trial (RCT) was conducted to investigate the effects of a low-carbohydrate high PUFA (LCPUFA) diet and a healthy Nordic diet (HND) on liver fat in men and women with type 2 diabetes (T2D) or prediabetes. The comparator diet (usual care (UC)) aligned with the Nordic Nutrition Recommendations. Liver fat decreased more in the LCPUFA diet and the HND versus UC. No difference in liver fat was observed between LCPUFA and HND. The LCPUFA diet and the HND improved several other cardiometabolic markers compared to UC, with more favorable improvements in the HND group.
In conclusion, findings from this thesis suggest that higher intakes of dietary unsaturated fatty acids (in particular PUFA) and lower intakes of SFA may be of importance for the prevention and treatment of NAFLD (at least for liver fat and fibrosis). Findings from this thesis also suggest that fatty acids reflecting both diet and endogenous metabolism may play a role in NAFLD.
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Molecular mechanism of plasmid copy number control in Yersinia
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-523712
The ability of pathogenic bacteria to cause disease depends on various virulence mechanisms. The three pathogenic species of Yersinia use a type III secretion system (T3SS) to translocate effector proteins into host cells and disrupt the immune system. This T3SS is encoded on a 70kb, low-copy, virulence plasmid. A novel mechanism of virulence was identified in Y. pseudotuberculosis, where the plasmid copy number (PCN) increases during infection. The PCN needs to be tightly regulated, as it encodes important, but costly, virulence genes. This thesis expends our understanding of PCN regulation and its importance in Yersinia virulence.
In Paper I, we demonstrate that PCN regulation as a virulence mechanism is a dynamic system capable of adapting to different host environments. We found that an increased PCN is important at the onset of infection, particularly during the colonization phase. In later stages, within different organs, the PCN decreases, suggesting a reduced need for the T3SS once the infection is established. This insight was enabled by the development of a novel method based on droplet digital PCR, allowing accurate PCN detection in sample with very little target DNA.
In Paper II, we studied the PCN regulation by YopD. We showed that YopD represses PCN through the regulation of copA transcription. This YopD-dependant PCN control is released when YopD is secreted outside the bacteria upon contact with the host cell. YopD is a multifunctional protein. It possesses different domains crucial for its different functions. We found that the domains important for T3SS regulation are also required for PCN regulation.
In Paper III, we used phenotypical approaches together with Nuclear Magnetic Resonance (NMR) method to study YmoA, a protein regulating gene expression in Yersinia in response to environmental stresses. YmoA’s ability to control gene expression requires its interaction with H-NS, a global DNA regulator. YmoA up-regulates a great number of genes, the T3SS and its effectors protein for instance. We observed that it also down-regulates many others, such as flagellar assembly genes. Our findings reveal that YmoA regulates PCN and senses temperature and osmotic stress resulting in a change of its conformation, which affects its ability to form a complex with H-NS.
In summary, the studies presented in this thesis show that PCN is a highly dynamic, tightly regulated mechanism, important for Yersinia pathogenesis.