Note:

Thesis (doctoral)--Lund University, 1998. / Thesis statement on t.p. verso. Includes bibliographical references.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1968. / Bibliography: leaves 144-149. / xiv, 149 l illus., tables

Thesis (M.A.)-- University of California, Santa Cruz, 1993. / Title supplied by cataloger.

No description available.

No description available.

No description available.

Working memory, which enables the temporary storage of information in an active “online” state, is an exceptionally capacity limited system. Given this capacity limit, irrelevant information in our environment must be filtered out, while relevant representation is maintained. Research has shown that neural oscillations in the alpha frequency range (8-12Hz) are greatly influenced by the number of items in memory. Most work has argued that alpha oscillations primarily support working memory processing by suppressing information that could interfere with items already in memory, as indexed by an increase in alpha power. However, other work has shown that decreases in alpha power, with little evidence of concurrent increases, support the maintenance of working memory representations. In this thesis we show that, in the context of visual working memory, the primary role of alpha oscillations is to maintain distinct working memory representations, rather than to suppress irrelevant information. This is shown in a series of three experiments all indicating that as the number of relevant items increases, the power of alpha oscillations systematically decreases. In the first experiment, we use a whole report and change detection task to examine how the number of items in memory influences alpha oscillations. In the second experiment, we use a cuing (Experiment 2A) and filtering (Experiment 2B) paradigm to demonstrate that alpha power tracks the number of remembered items instead of the number of total items on the screen. Lastly, by presenting items sequentially (Experiment 3A) or in overlapping locations (Experiment 3B), we see evidence that decreases in alpha power are related to the maintenance of relevant spatial locations, instead of the number of items in memory. The results of the experiments suggest that alpha power reflects the maintenance of relevant working memory representations, rather than the suppression of irrelevant external distractors or the inhibition of task-irrelevant neural areas. Furthermore, our last experiment indicates that the alpha frequency band is especially sensitive to the maintenance of spatial information.

by Kwong-bun Li. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1980. / Bibliography: leaves 260-295.

But : L’inflammation joue un rôle important dans la pathophysiologie de l’athérosclérose. Des marqueurs non spécifiques de l’inflammation tels que la Protéine C-Réactive (CRP) sont associés à un risque élevé de développer l’athérosclérose ou des complications aigues. Par sa capacité à se différencier en macrophage et à interagir avec différents types cellulaires, le monocyte joue un rôle essentiel dans l’athérogenèse. Afin de mieux caractériser le lien causal entre CRP et athérosclérose, nous avons étudié les effets de la CRP sur plusieurs aspects de la biologie du monocyte humain. Matériel et Méthodes : Les monocytes isolés du sang périphérique d’hommes jeunes (n=9) et de femmes pré ménopausées (n=9) en bonne santé ont été purifiés par gradient de Ficoll et sélection positive CD14, mis en culture pendant une nuit puis exposés à la CRP purifiée (25 µg/ml) pendant 12 ou 24 h. Une puce à oligonucléotides réalisée à façon par nos soins et contenant 250 gènes a permis d’effectuer le profilage de l’expression génique des monocytes traités ou non par la CRP. Les variations d’expression de certains gènes ont été confirmées par PCR quantitative et western blot. Résultats et Discussion : Nos résultats montrent que la CRP augmente l’expression des cytokines proinflammatoires IL-1 et IL-6, et des chimiokines IL-8 et Gro-beta. En revanche, la CRP diminue l’expression des MIP-1alpha, MIP-1beta et de l’alpha 2 macroglobuline. De plus, nous rapportons ici pour la première fois que la CRP augmente l’expression génique du récepteur nucléaire Liver X Receptor (LXR) alpha, facteur de transcription dont le rôle dans l’athérosclérose n’a été que récemment suggéré. Par western blot, nous montrons que l’augmentation d’expression du LXR alpha est suivie de sa translocation nucléaire. En conclusion, cette thèse montre que la CRP exerce à la fois des effets pro- et antiinflammatoires sur les monocytes humains ex-vivo. Nos résultats sont en faveur d’un rôle anti-athérogénique de la CRP de part son effet précédemment inconnu sur le LXR alpha. / Object : Inflammation plays an important role in the pathophysiology of atherosclerosis. Non specific inflammation biomarkers, such as C-Reactive Protein (CRP), are associated with a higher risk of developing atherosclerosis or other acute complications. By its capacity to differentiate into macrophages and to interact with other cells monocytes play a key role in atherogenesis. In order to better understand the causal link between CRP and atherosclerosis, we studied the effects of CRP on several aspects of human monocyte biology. Material and methods : Monocytes isolated from peripheral blood of healthy men (n=9) and healthy premenopausal women (n=9), were purified by Ficoll and CD14 positive selection, cultured over night then exposed to purified CRP (25 µg/ml) for 12 or 24h. A custom-made oligonucleotide array of 250 genes was used to analyse gene expression profiles of monocytes exposed or not to CRP. Changes in gene expression were confirmed by quantitative PCR and western blot. Results and Discussion : Our results show CRP increased pro-inflammatory cytokine (IL-1 and IL-6) and chemokine (IL-8 and Gro-beta) expression. In contrast, CRP decreased MIP-1 alpha, MIP-1 beta and alpha-2 macro-globuline expression. Furthermore, we were able to report, for the first time, that CRP increased gene expression of Liver X receptor (LXR) alpha, a transcription factor whose role in atherosclerosis has only recently been shown. Using western blot, we showed that the increased LXR alpha gene expression was followed by its nuclear translocation. In conclusion, this thesis suggests that CRP may have both pro and anti-inflammatory effects on the human monocyte ex-vivo. Our results argue in favor of an anti-atherogenic role of CRP, at least in part by its new effect on LXR alpha.