This thesis describes a geometric approach to integrable systems. In the first part we describe the geometry of Drinfeld--Sokolov integrable hierarchies including the corresponding tau-functions. Motivated by a relation between Drinfeld--Sokolov hierarchies and certain physical partition functions, we define a dispersionless limit of Drinfeld--Sokolov systems. We introduce a class of solutions which we call string solutions and prove that the tau-functions of string solutions satisfy Virasoro constraints generalizing those familiar from two-dimensional quantum gravity. In the second part we explain how procedures of Hamiltonian and quasi-Hamiltonian reductions in symplectic geometry arise naturally in the context of shifted symplectic structures. All constructions that appear in quasi-Hamiltonian reduction have a natural interpretation in terms of the classical Chern-Simons theory that we explain. As an application, we construct a prequantization of character stacks purely locally. / text

Cell culture media used in the manufacture of biopharmaceuticals conventionally contain many animal derived components. These components can harbor adventitious agents which can be transmitted through biotherapeutics, employed in the medical treatment of immunocompromised patients. An ADCF (animal derived component free) medium formulation obviates this concern. A rational method for the rapid and efficient screening and optimization of ADCF media while preserving, if not enhancing, cellular growth and protein productivity is needed. CHO (Chinese Hamster Ovary) cells, widely used as a production platform in industry, expressing a recombinant protein, were employed as a model system. Design of Experiment (DOE) and statistical analysis were employed to assess the impact of media formulation on cellular physiology. Metabolic flux, cellular growth, and protein productivity were evaluated as the measures of ADCF media formulation success. Measurements of extracellular metabolites were determined by HPLC and enzymatic methods. Recombinant protein production was measured by HPLC. This research demonstrates the successful screening and optimization of four plant hydrolysate mixtures (2 soy and 2 wheat) as a replacement for animal derived components. / NSERC, ABIN, MABNET

Adipose-derived stem cells (ASCs) have been extensively investigated for their applicability in the field of tissue engineering due to their multi-lineage differentiation potential and the convenience of cell acquisition. To date, conventional inductive media have been used to induce lineage-specific differentiation of ASCs; however, this general approach has limitations in terms of high costs and unstable differentiation responses. In native tissues, mesenchymal stem cells (MSCs) interact with their surrounding cells (i.e. mature cells) through paracrine and autocrine signaling, which can regulate their metabolism and cell function. Therefore, the author developed in vitro co-culture models to study the interactions between ASCs and three different mature cell types: adipocytes, chondrocytes and osteoblasts. In this work, bovine ASCs (bASCs) from the interdigital fat pad were first isolated and characterized, in terms of in vitro proliferation and multi-lineage (bone, cartilage, fat) differentiation with conventional inductive media and culture conditions. Doubling time calculations and gene expression analysis of stem cell markers indicated a threshold existed for stem cell degeneration at passage 5 (P5) for bASCs when expanded extensively in vitro. The multi-lineage differentiation potentials were compared between passage 2 (P2) and P5. Interestingly, while the P5 bASCs presented significantly lower levels of adipogenesis and chondrogenesis, osteogenesis was maintained or even improved with serial passaging. In the designed indirect co-culture systems, adipogenesis and chondrogenesis were investigated in growth medium without key differentiation factors, whereas osteogenesis was induced in conventional osteogenic medium, to maintain the stable phenotype of the mature osteoblasts in culture. The results were used to demonstrate the general feasibility of mature cell-induced or -enhanced bASC differentiation through soluble, cell-secreted paracrine signaling. When compared to growth factor (GF)-stimulated differentiation, the bASCs in co-culture presented an earlier, but potentially stronger, level of differentiation. Among these paracrine factors, Wnt proteins are known to play essential roles in mediating stem cell self-regulation and fate determination. In the current thesis, the Wnt inhibitors WIF-1 and DKK-1 were used to explore the involvement of the Wnt canonical and non-canonical signaling pathways in the designed co-culture environments. The data showed a strong correlation with the literature, indicating the canonical pathway was upregulated during osteogenesis, but inhibited during adipogenesis. The inhibition of chondrogenesis through the canonical pathway was suggested on a genetic level. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-03-09 13:39:14.553

Myeloid-derived suppressor cells (MDSCs), characterized by the co-expression of CD11b and Gr1, are a heterogeneous population of immature myeloid cells that exhibit strong suppressive functions against T cell responses. In inflammatory conditions like IBD, there is an increase in MDSCs but this is not sufficient to improve intestinal inflammation in IBD. Herein, we investigated the expansion of MDSCs in TNBS-induced acute colitis and whether the adoptive transfer of in vitro generated MDSCs ameliorated intestinal inflammation. We found that CD11b+Gr1+ MDSCs were significantly increased in experimental colitis. Further, this increase correlated to some extent with the severity of the disease. As per our protocol, MDSCs were generated from bone marrow cells co-cultured with hepatic stellate cells (HSCs), an essential cell type to obtain functional MDSCs in vitro. Adoptive transfer of HSC-induced MDSCs improved body weight loss and significantly downregulated inflammatory cytokines TNF, IFN-γ, and IL-17 in colonic tissue. Our results indicate MDSCs are immunoregulatory players in intestinal inflammation and that the adoptive transfer of in vitro generated MDSCs may provide a novel therapeutic approach for inflammatory bowel disease.

Myeloid-derived suppressor cells (MDSCs), characterized by the co-expression of CD11b and Gr1, are a heterogeneous population of immature myeloid cells that exhibit strong suppressive functions against T cell responses. In inflammatory conditions like IBD, there is an increase in MDSCs but this is not sufficient to improve intestinal inflammation in IBD. Herein, we investigated the expansion of MDSCs in TNBS-induced acute colitis and whether the adoptive transfer of in vitro generated MDSCs ameliorated intestinal inflammation. We found that CD11b+Gr1+ MDSCs were significantly increased in experimental colitis. Further, this increase correlated to some extent with the severity of the disease. As per our protocol, MDSCs were generated from bone marrow cells co-cultured with hepatic stellate cells (HSCs), an essential cell type to obtain functional MDSCs in vitro. Adoptive transfer of HSC-induced MDSCs improved body weight loss and significantly downregulated inflammatory cytokines TNF, IFN-γ, and IL-17 in colonic tissue. Our results indicate MDSCs are immunoregulatory players in intestinal inflammation and that the adoptive transfer of in vitro generated MDSCs may provide a novel therapeutic approach for inflammatory bowel disease.

The human monocyte-derived THP-1 cell line was incubated with 10mM AAPH in Earle’s Balanced Salt Solution at 37°C for up to 24 hours. Protein hydroperoxide formation occurred after an 8 hour lag phase which corresponded to glutathione loss observed in the cells. SDS-Page analysis confirmed protein degradation occurred after 6 hours. Cell viability measured by the MTT reduction assay also dropped after 8 hours. Reduction of intracellular glutathione levels using BSO caused reduction of the lag phase seen in protein hydroperoxide formation. Cell viability of BSO-treated cells was lower than control cells, indicating the initiation of apoptotic events. Flow cytometry analysis showed no difference between BSO-treated and control cells, indicating that GSH levels do not have an effect on the type of cell death observed in AAPH-induced oxidative damage on THP-1 cells. These results confirmed previous data in the lab suggesting THP-1 cells undergo AAPH-induced necrosis as a result of cellular damage, including the loss of GSH and the formation of protein hydroperoxides.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 7 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2003. / Härtill 4 uppsatser.

Thesis (Ph. D.)--Cornell University, May, 2008. / Vita. Includes bibliographical references (leaves 146-166).