| 1. |
- Devi, Priya
(författare)
-
Molecular characterization of the hepatitis C virus core protein
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hepatitis C virus (HCV) is an RNA virus that causes chronic infection, which can lead to hepatocellular carcinomas in humans. Besides liver diseases, the chronic HCV infection causes a broad spectrum of extrahepatic complications such as lymphoproliferative, metabolic and autoimmune disorders. Notably, HCV encoded core (C) protein is the major virion component that is involved in the oncogenesis and immune subversion. Therefore, detailed molecular characterization of the C protein provides a rational starting point for identification of novel countermeasures against pathogenic HCV infections. In this thesis we have investigated the suppressive effect of the C protein on T cell functions in immortalized cell lines and clinical samples.In paper I, we found that the expression of the C protein enhanced overall tyrosine phosphorylation in immortalized T cells. Interestingly, stable expression of the C protein specifically reduced accumulation of the tyrosine phosphatase SHP-1 mRNA. Our detailed bisulfite sequencing (BS) studies revealed that the SHP-1 P2 promoter was particularly hypermethylated at CpG1 and proximal islands in these cells. In paper II, we presented a new high-throughput next generation bisulfite sequencing (NGS-BS) protocol for the analysis of locus specific CpG methylation in HCV-infected cells using SHP-1 P2 as a model promoter. In line with our data from the BS, the NGS-BS method showed similar methylation profile at CpG1 island in immortalized cells. Strikingly, peripheral blood mononuclear cells (PBMCs) isolated from healthy controls and HCV-positive (HCV+) patients, showed much lower levels of methylation at the CpG1 island with no significant difference in DNA methylation pattern. In paper III, we investigated the mechanism of the C protein-mediated release of Ca2+ from intracellular stores. We identified two distinct regions in the N- and C-terminal parts of the protein that were essential for activation of the Ca2+/NFAT pathway. Of these, the N-terminal region was required for self-association of the C protein into nucleocapsid-like structures whereas the C-terminal part is essential for anchoring the protein to the ER-membrane. In paper IV, we presented a PCR based diagnostic method for the specific detection of positive and negative strand HCV RNA using primers with a non-viral tag. The method was evaluated by analysing the plasma and PBMC samples from chronic HCV+ patients.Taken together, our studies provide more detailed molecular characterization of the HCV C protein functions in immortalized as well as in HCV+ T cells. Importantly, specific DNA methylation pattern of the SHP-1 gene promoter may function as a potential prognostic marker for the disease progression in HCV-induced tumors. In addition, our updated PCR-based HCV diagnostic method may provide a more specific tool to monitor HCV infections in minor reservoirs.
|
|
| 2. |
- Hofverberg, Anders, 1985-
(författare)
-
Motivation, students, and the classroom environment : exploring the role of Swedish students’ achievement goals in chemistry
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overarching aim of this thesis is to deepen the knowledge about students’ achievement goals in chemistry and how they relate to students’ epistemic beliefs (beliefs about knowledge) and to their perceptions of classroom goal structures (instructional practices that emphasize certain achievement goals). Achievement goals are defined as the purpose behind students’ engagement in achievement behavior. They are important components in students’ motivation and influence students’ success and well-being in school. This thesis primarily focuses on two types of achievement goals: mastery and performance goals. Students with mastery goals define success in relation to prior performances and the task at hand and they strive to develop their competence. Students with performance goals define success in relation to others and they strive to demonstrate their relative competence. To study students’ achievement goals, questionnaire data and responses on a chemistry test were collected from Swedish and German students in Grades 5-11 and analyzed through statistical methods.The results show that it was possible to statistically differentiate between two different performance goals (striving to outperform others and avoid being outperformed by others) in the German data, but not in the Swedish. This challenges the universality of achievement goal models. Regarding the relationship between achievement goals and epistemic beliefs, the results indicated that sophisticated epistemic beliefs correlated with mastery goals and naïve beliefs correlated with performance goals. These relationships varied over time, especially in the transition from lower to upper secondary school, which therefore is an interesting time point to study further. The interaction between achievement goals and classroom goal structures was studied by using them as joint predictors of students’ autonomous motivation and performance on the chemistry test. The most important predictor for high autonomous motivation and high test scores was strong mastery goals. This effect was enhanced when students also perceived strong mastery structures in the classroom. Conversely, mastery goals were less beneficial if students pursued performance goals simultaneously. There were also differences in the interactions between achievement goals and goal structures over school years. Together, the results imply that teachers should support students’ mastery goals through striving to create classroom environments with strong mastery structures.In conclusion, this thesis highlights the complexity of achievement goals and their relations to other aspects of the educational context. This shows the need for future research to take, for example, the universality of achievement goal models and the importance of interaction effects into consideration.
|
|
| 3. |
- Söderström, Hanna, 1974-
(författare)
-
Semipermeable membrane devices as integrative tools for monitoring nonpolar aromatic compounds in air
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Air pollutants pose a high risk for humans, and the environment, and this pollution is one of the major environmental problems facing modern society. Active air sampling is the technique that has been traditionally used to monitor nonpolar aromatic air pollutants. However, active high volume samplers (HiVols) require a power supply, maintenance and specialist operators, and the equipment is often expensive. Thus, there is a need to develop new, less complicated sampling techniques that can increase the monitoring frequency, the geographical distribution of the measurements, and the number of sites used in air monitoring programs. In the work underlying this thesis, the use of semipermeable membrane devices (SPMDs) as tools for monitoring gas phase concentrations of nonpolar aromatic compound was evaluated using the compound classes polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkyl-PAHs) and nitrated PAHs (nitro-PAHs) as test compounds. High wind-speeds increased the uptake and release in SPMDs of PAHs and PCBs with log KOA values > 7.9, demonstrating that the uptake of most nonpolar aromatic compounds is controlled by the boundary layer at the membrane-air interface. The use of a metal umbrella to shelter the SPMDs decreased the uptake of PAHs and PCBs by 38 and 55 percent, respectively, at high wind/turbulence, and thus reduced the wind effect. Further, the use of performance reference compounds (PRCs) to assess the site effect of wind on the uptake in SPMDs reduced the between-site differences to less than 50 percent from as much as three times differences in uptake of PCBs and PAHs. However, analytical interferences reduced the precision of some PRCs, showing the importance of using robust analytical quality control. SPMDs were shown to be efficient samplers of gas phase nonpolar aromatic compounds, and were able to determine local, continental and indoor spatial distributions of PAHs, alkyl- PAHs and nitro-PAHs. In addition, the use of the SPMDs, which do not require electricity, made sampling possible at remote/rural areas where the infrastructure was limited. SPMDs were also used to determine the source of PAH pollution, and different approaches were discussed. Finally, SPMDs were used to estimate the importance of the gas phase exposure route to the uptake of PAHs in plants. The results demonstrate that SPMDs have several advantages compared with HiVols, including integrative capacity over long times, reduced costs, and no need of special operators, maintenance or power supply for sampling. However, calibration data of SPMDs in air are limited, and spatial differences are often only semi-quantitatively determined by comparing amounts and profiles in the SPMDs, which have limited their use in air monitoring programs. In future work, it is therefore important that SPMDs are properly sheltered, PRCs are used in the sampling protocols, and that calibrated sampling rate data, or the SPMD-air partition data, of specific compounds are further developed to make determination of time weighted average (TWA) concentrations possible.
|
|
