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No description available.

Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / "December 2001." Typescript. Vita. Includes bibliographical references (leaves 228-272). Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 84-100).

Abstract In this study, associations between periodontitis expression, serum levels of inflammatory markers and genetic factors were investigated. The periodontal status of 56 subjects with chronic periodontitis, 28 control subjects and 80 subjects with type I diabetes mellitus (DM) was examined. In addition, a reference group (n=178) with genetic but not with periodontal health data was included. The single nucleotide polymorphisms of CD14 -260, IL-6 -174, TNF-α -308, IL-10 -1082, IL-1A -889, IL-1B +3954, and TLR4 +896 were determined using PCR with RFLP or allele-specific primers, and comparisons of the genotype frequencies were made between the study groups and reference subjects. The serum concentrations of IL-6 and sCD14 were assayed using ELISA. The distributions of all the studied genotypes were similar in the periodontitis and the reference subjects. However, in the periodontitis group, the carriage of the T-containing genotype of the CD14 -260 and the GG genotype of the IL-6 -174 associated significantly with the extent of periodontitis, indicating that genetic factors play a role in the pathogenesis of the disease. Both the extent of periodontal infection and the IL-6 -174 genotype were significant determinants for the serum IL-6 level, subjects carrying the GG genotype having significantly higher serum IL-6 levels than those carrying the CC/CG genotype. The serum level of sCD14 was significantly higher in subjects carrying the T-containing than the CC genotype of the CD14 -260 in the control group but not in the periodontitis group, suggesting that severe periodontal infection overshadows the influence of the genotype on serum sCD14 level. Overall, the serum studies indicated that periodontal infection is associated with a low-grade systemic inflammatory response. Type 1 DM subjects carrying the GG genotype of the IL-6 -174 had a higher extent of periodontitis when compared with those carrying the CG/CC genotype. Our results also suggest that the IL-6 -174 genotype is a more significant determinant of the extent of periodontitis in type 1 DM than glycemic control.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.

O parasita da malária Plasmodium falciparum percebe o ambiente em que se encontra, elaborando respostas celulares adequadas, que envolvem secreção de proteínas, crescimento e diferenciação celular. Fatores relacionados com a geração de segundos-mensageiros e proteínas efetoras da sinalização celular estão descritos na literatura. Porém, a função de receptores responsáveis pela percepção de estímulos extracelulares no parasita é um tema pouco explorado. A identificação in silico de receptores de sete domínios transmembrânicos putativos no genoma de P. falciparum possibilitou a exploração da função dos mesmos. A tese caracteriza funcionalmente dois receptores, PFSR10 e PFSR25. A expressão proteica dos receptores foi demonstrada em fases eritrocíticas de P. falciparum. Os receptores possuem candidatos a parceiros moleculares que executam diversas funções celulares, entre elas invasão do eritrócito, endocitose e exocitose. Os receptores foram transfectados em células de mamíferos e, através de ensaios de dinâmica de cálcio de high-throughput, sugere-se que PFSR10 codifique um receptor que participa na percepção de ATP extracelular e que PFSR25 codifique um sensor de KCl. O trabalho também sugere que KCl modula cálcio citosólico em P. falciparum e que parasitas nocaute para PFSR25 são incapazes de modular cálcio citosólico em resposta a KCl. / The malaria parasite P. falciparum perceives its milieu and elaborates adequate intracellular responses, that involve protein secretion, growth and cell differentiation. Factors related to second messengers generation and effectors of cell signaling are described in the literature. However, the function of receptors responsible for stimulus perception remains elusive. The in silico identification of putative seven transmembrane receptors in the Plasmodium falciparum genome allowed the exploration of their function. In the thesis, two putative receptors were characterized, PFSR10 and PFSR25. The proteic expression of the receptors was demonstrated in erythrocytic stages of P. falciparum. The receptors have putative interaction partners that participate in cellular functions such as invasion, exocytosis and endocytosis.The receptors were transfected in mammalian cells and, through high-throughput calcium dynamics assays, it is suggested that PFSR10 codes for a receptor that participates in extracellular ATP perception and that PFSR25 codes for a KCl sensor. It is also suggested that KCl modulates cytosolic calcium in response to KCl and that knockout parasites for PFSR25 are incapable of modulating cytosolic calcium in response to KCl.

<p>Integrins are receptors presented on most cells. By binding ligand they can generate signalling pathways inside the cell. Those pathways are a linkage to proteins in the cytosol. It is known that tumor cells can survive and proliferate in the absence of a solid support while normal cells need to be bound to ligand. To understand why tumour cells act that way, we first have to know how ligand-binding to integrins affect the cell. This research field includes studies on activation of proteins by integrins and the following protein-protein interactions.</p><p>The part of the research that I did, focused on the activation of PI3K by integrins and the question whether Ras is included in that pathway. I also studied the conformation changes of the integrins and tried to identify factors which regulate these changes.</p><p>Known is that Ras can activate PI3K. But we wanted to know if this is a step in the activation of PI3K by integrins. So if this would be a fact then Ras must be activated by integrins.</p><p>To see if integrins could activate Ras I did a pull down assay. GTP loaded Ras was isolated through its affinity for Raf. Only when Ras is in its activated state then it is GTP loaded, otherwise it is GDP loaded. In the experiment we also compared the β1A and the β1B splice variants. As result we could see that both splice variants probably can activate Ras. By blotting with anti-PI3K antibody we looked if PI3K had bound to Ras but no clear result could be obtained.</p><p>Integrins presented on blood cells are mostly in the inactive state while adherent cells have integrins which are mostly in the active state. PI3K has been shown, for blood cells, to be involved in the conformation regulation of integrins. Possibly, there is a positive circle that for blood cells just has to be switched on. It could be that the integrins in adherent cells are active because the cells are adhesive. By being adhesive, PI3K is activated. PI3K may then activate the integrins, through which the integrins stay in the active state. This circle could be broken at two points: we could inhibit PI3K or we could make the cells un-adhesive. I analysed this in cell attachment assay and by binding of conformation-specific integrin antibodies in FACScan. From the results we could not find any evidence that the whole idea around the positive circle is correct. Surprisingly we saw that the integrin value at the surface decrease if you add PI3K inhibitor. This could be due to distribute recirculation of integrins from the cytoplasm to the cell surface.</p><p>β1- and β3-integrins are both widely spread, but no functional difference could be shown already. Previous results suggest that there is a difference between migrations of those two types. To ensure this suggestion I did a wound assay. Hereby I compared the migration of different cell types, with different integrins on their surface and on different ligands.</p>

Integrins are receptors presented on most cells. By binding ligand they can generate signalling pathways inside the cell. Those pathways are a linkage to proteins in the cytosol. It is known that tumor cells can survive and proliferate in the absence of a solid support while normal cells need to be bound to ligand. To understand why tumour cells act that way, we first have to know how ligand-binding to integrins affect the cell. This research field includes studies on activation of proteins by integrins and the following protein-protein interactions. The part of the research that I did, focused on the activation of PI3K by integrins and the question whether Ras is included in that pathway. I also studied the conformation changes of the integrins and tried to identify factors which regulate these changes. Known is that Ras can activate PI3K. But we wanted to know if this is a step in the activation of PI3K by integrins. So if this would be a fact then Ras must be activated by integrins. To see if integrins could activate Ras I did a pull down assay. GTP loaded Ras was isolated through its affinity for Raf. Only when Ras is in its activated state then it is GTP loaded, otherwise it is GDP loaded. In the experiment we also compared the β1A and the β1B splice variants. As result we could see that both splice variants probably can activate Ras. By blotting with anti-PI3K antibody we looked if PI3K had bound to Ras but no clear result could be obtained. Integrins presented on blood cells are mostly in the inactive state while adherent cells have integrins which are mostly in the active state. PI3K has been shown, for blood cells, to be involved in the conformation regulation of integrins. Possibly, there is a positive circle that for blood cells just has to be switched on. It could be that the integrins in adherent cells are active because the cells are adhesive. By being adhesive, PI3K is activated. PI3K may then activate the integrins, through which the integrins stay in the active state. This circle could be broken at two points: we could inhibit PI3K or we could make the cells un-adhesive. I analysed this in cell attachment assay and by binding of conformation-specific integrin antibodies in FACScan. From the results we could not find any evidence that the whole idea around the positive circle is correct. Surprisingly we saw that the integrin value at the surface decrease if you add PI3K inhibitor. This could be due to distribute recirculation of integrins from the cytoplasm to the cell surface. β1- and β3-integrins are both widely spread, but no functional difference could be shown already. Previous results suggest that there is a difference between migrations of those two types. To ensure this suggestion I did a wound assay. Hereby I compared the migration of different cell types, with different integrins on their surface and on different ligands.