Regensburg, Univ., Diss., 2009.

No description available.

A fundamental question in the study of memory is: Why do we remember some events but forget others? It has been proposed that people preferentially remember motivationally relevant information, as these memories may be useful in guiding choices in the future, a framework called adaptive memory. This dissertation examined the brain mechanisms that support adaptive memory, specifically focusing on how memory is shaped by rewards and dopamine, using a combination of pharmacological manipulations and behavioral assays. First, we found that rewards retroactively prioritize memory for preceding neutral events, and consistent with models of hippocampal replay, two periods of consolidation are necessary for this effect: a period of rest immediately following encoding and overnight consolidation. Second, motivated by research showing that neurotransmitters, such as dopamine, potentiate motivationally relevant memories to endure over long durations, we administered d-amphetamine (a dopamine agonist) before encoding. We found that when hippocampus dependent memory is tested after a short delay, working memory best accounts for memory performance, but when tested after a long delay, d-amphetamine level directly predicts memory performance. And third, we tested how d-amphetamine modulates different memory systems after a delay, using two different behavioral paradigms in which participants learned about overlapping associations using either stimulus-response learning or deliberate associative encoding. In both experiments, we found that d-amphetamine during encoding enhanced test performance on the trained items a week later; however, we did not detect any evidence that d-amphetamine modulates the integration of the overlapping pairs. Together, the work reported in this dissertation suggests that memory for motivationally relevant information is prioritized, dopamine enhances performance across different memory and learning systems, the effect of both reward and dopamine on memory and learning emerge after consolidation, and dopamine does not bias the hippocampus to encode memories in an integrated manner.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Food Science." Includes bibliographical references (p. 89-91).

Thesis (M.Sc.)--York University, 2009. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 137-145). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR51628

A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy Johannesburg, 2011. / The phosphotidylinositide-3-kinase (PI3K) pro-survival signalling pathway is critical in the development of cancer. Major contributors to the proliferative and/or anti-proliferative signalling in human oesophageal squamous cell carcinoma (HOSCC) are currently unknown. Based on the Ser473 phosphorylation state of PKB (pPKB), this study dissects the overall activation status of the PI3K/PKB pathway. Despite the prevalent membrane expression of PI3K determined through western blotting and immunofluorescence, pPKB levels were shown to be surprisingly low. Activation of EGFR did not produce a hyperactivation of the PI3K/PKB pathway. Neither PI3K nor PKB sequence isolated from the 5 HOSCC cell lines possessed any of the ―hotspot‖ mutations described previously for other tumours. Inhibiting phosphatase protein 2A (PP2A), an integral antagonist of PKB, indicated that its activity in respect of PKB is diminished in HOSCC cells. Despite the low concentration of pPKB, the reciprocal relationship with PTEN expression was not evident in the WHCO and SNO HOSCC series. Moreover, reversible oxidization and inhibition of PTEN served to augment the activation of the PI3K/PKB pathway. Since oxidation of PTEN is imperative for effective signal propagation from activated EGFR and PI3K, these data reveal an aberrant EGFR-PI3K-H2O2 mediated PTEN inhibition in HOSCC. Allied to this discovery, was the finding that HOSCC cells are highly susceptible to oxidative stress induced by H2O2. This was suggested to play an essential part in maintaining the low PI3K/PKB activation status. Although the decrease in PTEN activity was required for the induction of pPKB, PTEN may not be the only limiting component for the activation of the PI3K/PKB pathway in HOSCC. In addition to its overexpressed EGFR status, the WHCO and SNO HOSCC series have the propensity to appropriate nuclear β-catenin. Interruption of the PI3K/PKB signalling pathway caused a small, yet significant, depression in the nuclear localization of β-catenin in 3 of the HOSCC cell lines. Together, this work greatly expands our understanding of the major influences behind the proliferative and/or anti-proliferative signalling in HOSCC, primarily that, the EGFR overexpression status does not propagate these transforming capabilities via activation of the PI3K/PKB pathway, and that this may be a reflection of its transformation potential. The findings derived from this study are likely to have a profound impact on future therapeutic targets for this disease.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 167-170). Also available via the Internet.

Thesis (Ph. D.)--Illinois State University, 1983. / Title from title page screen, viewed May 10, 2005. Dissertation Committee: Arlan Richardson, Joshua Fierer (co-chairs), H. Tak Cheung, Harry Huizinga, Mathew Nadakavukaren. Includes bibliographical references (leaves 130-144) and abstract. Also available in print.

Immune Cell Potentiating Factor (ICPF) represents a class of biological response modifiers initially only found within active caprine serum fractions. Controlled studies have since demonstrated active ICPF derived from several non-caprine mammalian sources; including equine and human. ICPF is able to increase survivability in murine gram negative induced sepsis (60%) as well as secondary infection and subsequent sepsis in canines infected within canine parvo virus 2 (36%) despite showing no innate antiviral properties. ICPF is able to initiate systemic proteomic changes within several organ systems; including serum, liver, brain, lung, and spleen. ICPF initiated an early acute phase response, specifically through the increased expression of serum amyloid A, with systemic serum levels increasing from 1.5 μg/mL to 403.0 μg/mL within 24 hours and increased to 3,400 μg/mL within 48 hours following ICPF administration. Evaluation of cytokine expression following ICPF treatment revealed the up-regulation of IL-6, INF-γ, and the chemokine CXCL1\KC in vivo as well as the expression of IL-6 and IFN-γ in vitro within 3 hours of treatment. Development of an in vitro bioassay through the expression of IL-6 and IFN-γ within whole blood and peripheral blood mononuclear cells will allow for further elucidation and testing of ICPF outside of an animal host. The early expression of proinflammatory cytokines and chemokines, an acute phase response including serum amyloid A, and ICPF’s inability to alleviate mortality in a lipopolysaccharide animal mortality model strongly indicates an active role for ICPF as an immune regulatory peptide capable of promoting an early inflammatory response to Salmonella enterica serovar Typhimurium thereby reducing the risk and mortality associated with sepsis.

Thesis (PhD)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Alkali-soluble rheology modifiers are commercially synthesised via conventional freeradical polymerisation processes. This results in the end product having certain limitations; there is poor control over the molar mass, molar mass distribution and chain architecture of the polymer chains. These limitations can be overcome by using a controlled/living free radical polymerisation process, for example the RAFT process. This alternate method of synthesis was used here to prepare model alkali-soluble rheology modifiers. The structure/property relationships of model alkali-soluble rheology modifiers synthesised via the RAFT process were studied. Model alkali-soluble rheology modifiers of different molar masses and chain architectures (block, co- and ter-polymers) were successfully synthesised by the RAFT polymerisation of methyl methacrylate, methacrylic acid and various hydrophobic macromonomers. The different types of alkali-soluble rheology modifiers were synthesised in solution and in miniemulsion. Each of the two systems had certain advantages and disadvantages. The conversion limit of reactions in solution was about 60 % and reaction times were much slower than those of the miniemulsion reactions. Higher final conversions were recorded for miniemulsion reactions, reactions were faster and no solvent removal was required. Unfortunately it was not possible to synthesise all the different types of associative rheology modifiers investigated here in a miniemulsion system. The latex solutions thickened with conventional rheology modifiers (co-polymers) show very contrasting behaviour (rheology profile and dynamic properties) to that of the latex solutions thickened with the associative rheology modifiers (ter-polymers). The AB block copolymers gave the latex solutions rheology results between those obtained with conventional rheology modifiers and those with the associative rheology modifiers. Varying the number of ethylene oxide spacer units in the hydrophobic macromonomers of the associative rheology modifiers had a significant influence on the rheology properties of the latex and alkali solutions. As the number of ethylene oxide spacer units was increased from 20 to 100 there was a significant increase in the zero-shear viscosity of the latex solutions thickened with the associative rheology modifiers. Contrasting results were obtained for the polymer solutions (no latex present), where the use of the associative rheology modifiers containing the highest number (EO = 100) of ethylene oxide spacer units resulted in solutions with the lowest viscosity, but the rheology modifiers containing the 50 ethylene oxide spacer units gave the highest steady shear viscosity. / AFRIKAANSE OPSOMMING: Alkali-oplosbare reologie-modifiseerders word kommersieël gesintetiseer d.m.v. konvensionele vrye-radikaal polimerisasieprosesse. Hierdie prosesse lewer gewoonlik 'n eindproduk met sekere tekortkominge, a.g.v. swak beheer oor molekulêre massa, molekulêre massa-verspreiding, en polimeerkettingstruktuur (Eng. chain architecture). Hierdie tekortkominge kan oorbrug word deur gebruik te maak van 'n beheerde/lewende vrye-radikaal polimerisasieproses, soos byvoorbeeld die RAFT-proses (Eng. RAFT: reversible addition-fragmentation chain transfer polymerisation). Hierdie alternatiewe metode is in die studie gebruik om model alkali-oplosbare reologiemodifiseerders te sintetiseer. Die struktuur-eienskapverhoudings van die model alkali-oplosbare reologie modifiseerders wat d.m.v. die RAFT-proses gesintetiseer is, is bestudeer. Model alkali-oplosbare reologiemodifiseerders van verskillende molekulêre massas en kettingstrukture (blok, ko- en ter-polimere) is suksesvol gesintetiseer d.m.v. RAFT-polimerisasie van metielakrilaat, metakrielsuur en hidrofobiese makromonomere. Die verskillende alkali-oplosbare reologiemodifiseerders is in organiese oplosmiddel sowel as in mini-emulsie gesintetiseer. Elkeen van die sisteme het sekere voordele en nadele getoon. In die reaksies wat in organiese oplosmiddels gedoen is, is slegs 60 % van die monomere ingebou in die polimeerkettings en die tydsduur van hierdie reaksie was heelwat langer as by die wat uitgevoer is in mini-emulsie. Meer as 60 % van die monomere is omgeskakel na polimeer tydens die reaksies wat in mini-emulsie uitgevoer is, die reaksietempo was vinniger en dit was nie nodig om die organiese oplosmiddel te verwyder nie. Ongelukkig was dit nie moontlik om al die verskillende tipes assosiatiewe-reologiemodifiseerders (Eng: associative rheology modifiers) in miniemulsie te sintetiseer nie. Die lateks wat met konvensionele reologiemodifiseerders (ko-polimere) verdik is, het kontrasterende eienskappe (reologie-profiel en dinamiese eienskappe) getoon teenoor die van die lateks-oplossings wat met assosiatiewe-reologiemodifiseerders (ter-polimere) verdik is. Die AB-tipe blok ko-polimere gee reologieresultate vir die lateks-oplossings wat lê tussen die wat bepaal is vir konvensionele reologieodifiseerders en assosiatiewe reologiemodifiseerders. Variasie in die aantal etileenoksiedeenhede in die hidrofobiese makromonomere van die assosiatiewe reologiemodifiseerders het 'n betekenisvolle invloed op die reologie-eienskappe van die lateks, sowel as die alkali-oplossings gehad. Namate die aantal etileenoksiedeenhede van 20 tot 100 vermeerder is, het 'n betekenisvolle verhoging in die "zero-shear " viskositeit van die lateks oplossings wat met die assosiatiewe reologiemodifiseerders verdik is voorgekom. Teenstrydige resultate is verkry vir die polimeeroplossings met geen lateks teenwoordig nie: die assosiatiewe reologiemodifiseerders met die hoogste aantal etieleenoksiedeenhede (EO = 100) het die laagste viskositeitsresultate opgelewer en die reologiemodifiseerders met slegs 50 etieleenoksiedeenhede het die hoogste viskositeitsresultate gelewer.