Refine
Year of publication
Document Type
- Doctoral Thesis (2052) (remove)
Language
- English (2052) (remove)
Has Fulltext
- yes (2052)
Is part of the Bibliography
- no (2052)
Keywords
- ALICE (8)
- Quark-Gluon-Plasma (8)
- Membranproteine (7)
- Geldpolitik (6)
- Proteine (6)
- Apoptosis (5)
- Biochemie (5)
- Heavy Ion Collisions (5)
- Immunologie (5)
- LHC (5)
Institute
- Biowissenschaften (424)
- Physik (377)
- Biochemie und Chemie (281)
- Biochemie, Chemie und Pharmazie (207)
- Medizin (125)
- Pharmazie (92)
- Geowissenschaften (87)
- Informatik und Mathematik (85)
- Informatik (54)
- Mathematik (46)
Chemokines play a key role in the cellular infiltration of inflamed tissue. They are released by a wide variety of cell types during the initial phase of host response to injury, allergens, antigens, or invading microorganisms, and selectively attract leukocytes to inflammatory foci, inducing both migration and activation. Monocyte chemoattractant protein-1 (MCP-1), a member of the CC chemokine superfamily, functions in attracting monocytes, T lymphocytes, and basophils to sites of inflammation. MCP-1 is produced by monocytes, fibroblasts, vascular endothelial cells and smooth muscle cells in response to various stimuli such as tumour necrosis factor-a (TNF-a), interferon-g (IFN-g), and interleukin-1b (IL-1b). It also plays an important role in the pathogenesis of chronic inflammation, and overexpression of MCP-1 has been implicated in diseases including glomerulonephritis and rheumatoid arthritis. Oligonucleotide-directed triple helix formation offers a means to target specific sequences in DNA and interfere with gene expression at the transcriptional level. Triple helix-forming oligonucleotides (TFOs) bind to homopurine/homopyrimidine sequences, forming a stable, sequence-specific complex with the duplex DNA. Purine-rich sequences are frequent in gene regulatory regions and TFOs directed to promoter sequences have been shown to prevent binding of transcription factors and inhibit transcription initiation and elongation. Exogenous TFOs that bind homopurine/ homopyrimidine DNA sequences and form triple-helices can be rationally designed, while the intracellular delivery of single-stranded RNA TFOs has not been studied in detail before. In this study, expression vectors were constructed which directed transcription of either a 19 nt triplex-forming pyrimidine CU-TFO sequence targeting the human MCP-1 or two different 19 nt GU- or CA-control sequences, respectively, together with the vector encoded hygromycin resistance mRNA as one fusion transcript. HEK 293 cells were stable transfected with these vectors and several TFO and control cell lines were generated. Functional relevant triplex formation of a TFO with a corresponding 19 bp GC-rich AP-1/SP-1 site of the human MCP-1 promoter was shown. Binding of synthetic 19 nt CUTFO to the MCP-1 promoter duplex was verified by triplex blotting at pH 6.7. Underlining binding specificity, control sequences, including the GU- and CA-sequence, a TFO containing one single mismatch and a MCP-1 promoter duplex containing two mismatches, did not participate in triplex formation. Establishing a magnetic capture technique with streptavidin microbeads it was verified that at pH 7.0 the 19 nt TFO embedded in a 1.1 kb fusion transcript binds to a plasmid encoded MCP-1 promoter target duplex three times stronger than the controls. Finally, cell culture experiments revealed 76 ± 10.2% inhibition of MCP-1 protein secretion in TNF-a stimulated CU-TFO harboring cell lines and up to 88% after TNF-a and IFN-g costimulation in comparison to controls. Expression of interleukin-8 (IL-8) as one TNF-a inducible control gene was not affected by CU-TFO, demonstrating both highly specific and effective chemokine gene repression. Furthermore, another chemokine target, regulated upon activation normal T cell expressed and secreted (RANTES), which plays an essential role in inflammation by recruiting T lymphocytes, macrophages and eosinophils to inflammatory sites, was analysed using the triplex approach. A 28 nt TFO was designed targeting the murine RANTES gene promoter, and gel mobility shift assays demonstrated that the phosphodiester TFO formed a sequencespecific triplex with the double-stranded target DNA with a Kd of 2.5 x 10-7 M. It was analysed whether RANTES expression could be inhibited at the transcriptional level testing the TFO in two different cell lines, T helper-1 lymphocytes and brain microvascular endothelial cells (bend3 cells). Although there was a sequence-specific binding of the TFO detectable in the gel shift assays, there was no inhibitory effect of the exogenously added and phosphorothioate stabilised TFO on endogenous RANTES gene expression visible. Additionally, the small interfering RNA (siRNA) approach was tested as another strategy to inhibit expression of the pro-inflammatory chemokines MCP-1 and RANTES. Two different methods were pursuit, describing transient transfection with vector derived and synthetic siRNA. The vector pSUPER containing the siRNA coding sequence was used to suppress endogenous MCP-1 in HEK 293 cells. An empty vector without RNA sequence served as a control. Inhibition due to the siRNA was measured in stimulated and unstimulated cells. In TNF-a stimulated cells MCP-1 protein synthesis was decreased by 35 ± 11% after siRNA transfection. Using a synthetic double-stranded siRNA, the TNF-a induced MCP-1 protein secretion could be successfully inhibited about 62.3 ± 10.3% in HEK 293 cells, indicating that the siRNA is functional in these cells to suppress chemokine expression. The siRNA approach targeting murine RANTES in Th1 cells and b-end3 cells revealed no inhibition of endogenous gene expression. Gene therapy approaches rely on efficient transfer of genes to the desired target cells. A wide variety of viral and nonviral vectors have been developed and evaluated for their efficiency of transduction, sustained expression of the transgene, and safety. Among them, lentiviruses have been widely used for gene therapy applications. In order to improve the delivery of TFOs or siRNAs into the target cells, cloning of the lentiviral transfer vector SEW, the production of lentiviral particles by transient transfection were performed with the aim to generate lentiviral vector-derived TFOs in further experiments. Here, Th1 cells were transduced with infectious lentiviral particles and transduction efficacy was measured. Transduction efficacy higher than 82% could be achieved using the lentiviral vector SEW, opening optimal possibilities for the TFO or siRNA approach.
Canada’s geographic centre lies in the Territory Nunavut. From here the distance to the geographic North Pole is as far as to the US border. Nunavut takes up about 1/5 of the Canadian land mass but has by far the smallest population with currently about 38,000 residents. 85% of its population are Inuit whose culture dramatically changed within the last 70 years.
As a result, the territory is dealing with several generations of Inuit that are traumatized or at least severely affected by cultural and economic changes that started after World War 2 with the resettlement from the land into permanent communities. No matter if we are talking about the actual elders, mid-age adults or pre-teenagers, each of this generation experienced and still experiences various personal and cultural challenges of identity, financial and housing insecurity, food insecurity, substance abuse education, change of social values ranging from inter-generational and gender relationships to the introduction of a foreign political and legal system.
On the other side, a lot of the traditional societal values are still being practiced in Inuit families. Despite all the tragedies that several generations of Inuit have experienced by now, the society keeps generating the strength and cultural pride that allows many Inuit both, as individuals and as a collective under the umbrella of either Inuit Land Claims or not for profit organizations to advocate on behalf of Inuit culture, to fight for more acknowledgement of Inuit culture and to enhance pride in the historic and present day cultural achievements of Nunavut’s indigenous population.
The social issues, inter- and intra-cultural processes described in my thesis are not exclusive to the situation in Nunavut or to Inuit. Studies from other regions, in Canada or from around the world (LaPrairie 1987; Jensen 1986; Nunatsiaq News 6/30/2010) reveal similar challenges.
Though many structural similarities can be identified by comparing these studies with each other, e.g. marginalization of the indigenous local population, colonization, paternalism and resulting issues like personal and cultural identity loss, it is important to have a more in depth look into the single cases to determine which individual events and developments causes and maybe still cause such a devastating social situation as it is found among many indigenous peoples across the world. From my perspective effective improvements of the situation of a group, a respective community or region can only happen when particularities of socialization, communication and philosophy in the single cultural entities are being considered.
That is why my thesis will exclusively focus on developments in Nunavut and use various case studies of communities. The case studies shall help to identify local differences in historic and recent developments and thus provide starting points for explanations of different developments in different Nunavut communities.
The thesis is looking at both, historic and recent root causes for the many issues in Nunavut.
The data that my my thesis is based on are a combination of literature and about 60 formal and informal interviews that I conducted in three Nunavut communities (Iqaluit, Whale Cove, Kugluktuk) during my 18 months of field work between October 2008 and March 2010. Many more spontaneous unstructured conversations between me and community members added to the pool of first-hand information that I gathered.
Since my field work is limited to those three communities it has a very strong qualitative character. The quantitative side, which allows me to confidently apply my research analyses to entire Nunavut, comes from literature research as well as many informal conversations and a few formal interviews that I conducted with people who had some experience in other communities than Iqaluit, Kugluktuk and Whale Cove.
Furthermore, while I was living at the old residence of the Nunavut Arctic College in Iqaluit, I spend time with college students from across Nunavut. Through them, I obtained „case studies “from following communities: Iqaluit, Qikiqtarjuaq, Kimmirut, Pangnirtung, Clyde River, Pond Inlet, Igloolik, Repulse Bay, Cape Dorset, Chesterfield Inlet, Baker Lake, Rankin Inlet, Whale Cove, Arviat, Taloyoak, Kugluktuk.
My general categorization of “early contact period”, “contact”, “1st generation” and “2nd generation” is very similar to Damas’ terms of “early contact phase”, “contact – traditional”, “resettlement” that he uses to create a timeline that describes the major phases of impact for Inuit society (Damas 2002: 7, 17).
Chapters 2 is meant to provide an inventory of the key aspects of current social issues in Nunavut. In this context I am looking at the four major aspects that in my opinion shape Nunavut’s society:
1) violence and other forms of social dysfunctions
2) the associated services and delivering agencies that try to address those matters
3) Education
4) Inuit cultural particularities in communication and socialization
Those four areas are forming the foundation for the rest of my work. The following chapters will guide the reader through the historic transformation process of Inuit pre-colonial semi-nomadic society to a society that is living in permanent settlements, strongly influenced if not in many ways dominated by Euro-Canadian culture. Each of those chapters will be referring to the social and cultural changes that happened in the different time periods that I labeled with “Pre-settlement, First, Second, and Third Generation”. The relevance of violence and other social dysfunctions, their context and strategies how each generation dealt with those matters will be analyzed while I will be also referring to the impacts that non-Inuit, primarily Euro-Canadians and Euro-Americans had and have on Inuit society.
...