Conselho Nacional de Desenvolvimento Científico e Tecnológico / Liquid crystalline precursors are surfactant systems that can contain active substances as Citrus sinensis essential oil (CSEO) with exhibits biological activity against Aedes aegypti (Ae. aegypti) larvae. These systems can undergo into phase transition in aqueous solution and become more structured aggregates. Thereby, the aim of this work was to obtain and characterize nanostructured systems through water/ oil stabilized by polyoxypropylene (5) polyoxyethylene (20) cetyl ether (procetyl AWS®, PPG-5 CETETH-20) surfactant to obtain a system that in contact with aqueous fluids becomes a high viscosity liquid crystal mesophase with potential application on Ae. aegypti larvicidal control. First, the phase diagram was constructed in order to obtain the systems, composed by water, PPG-5 CETETH-20: oleic acid (OA) 1:1 and 2:1 and CSEO. There was performed critical micelle determination of PPG-5 CETETH-20, PPG-5 CETETH-20: OA 1:1 and 2:1. The systems were evaluated by polarized light microscopy (PLM), small angle X-ray scattering (SAXS), rheology and lethal concentration evaluation against Ae. aegypti larvae. PPG-5 CETETH-20 has shown CMC= 0,2 g/ L, PPG-5 CETETH-20: OA 1:1 CMC= 0,077 g/ L and 2:1 CMC= 0,0578 g/ L, indicating that there is a synergism between the surfactant and cosurfactant for lowering the surface tension. In the phase diagram 2:1, there were observed four regions: liquid crystal (LC), emulsion, microemulsion (ME) and phase separation, however in the 1:1 phase diagram, the LC region wasn t observed. The microscopy distinguished isotropic systems like MEs from anisotropic as lamellae and hexagonal LCs. SAXS measurements confirmed PLM structures, with broad bands of low intensity for MEs (all samples from 1:1 and six samples from 2:1), phase transition and for lamellar LC structure, the positions of the peaks should obey the relationship 1:2:3 and 1:√3:√4 for hexagonal. The rheological analysis showed that ME and phase transitions ME-LC presents Newtonian behavior, while LC presents non-newtonian behavior and the increase of aqueous phase increases the LC elasticity modulus. The larvicidal activity the samples A3 (15% A/ 5% OECS/ 80% PPG-5 CETETH-20: AO) and A4 (20% A/ 5% OECS/ 75% PPG-5 CETETH-20: AO) of diagram 2:1 exhibited LC50 6,55 ppm and 5,93 pm, respectively, indicating that these systems microstructure has improved the oil solubility in aqueous medium. Thereby, it can be concluded that there were obtained liquid crystalline precursors with a potential use against Ae. aegypti larvae. / Precursores de fase líquido-cristalina são sistemas estabilizados por tensoativos que podem conter substancias ativas como o óleo essencial de Citrus sinensis (OECS), apresenta atividade contra as larvas do Aedes aegypti (Ae. aegypti). Esses sistemas podem sofrer transição de fase em contato com meio aquoso e se transformar em agregados mais estruturados. Desse modo, o objetivo do trabalho foi obter e caracterizar sistemas nanoestruturados a partir da utilização de água/óleo estabilizados por tensoativo do tipo álcool graxo etoxilado e propoxilado (procetyl AWS®, PPG-5 CETETH-20) visando obter um sistema que, em contato com fluidos aquosos, se converta numa mesofase líquido-cristalina de alta viscosidade, com potencial aplicação no controle larvicida do Aedes aegypti. Primeiramente, os sistemas foram obtidos através da construção do diagrama de fases composto por água (A), PPG-5 CETETH-20: ácido oléico (AO) nas proporções 1:1 e 2:1 e OECS. Foi realizada a determinação da concentração micelar crítica (CMC) do PPG-5 CETETH-20 e das misturas PPG-5 CETETH-20: AO 1:1 e 2:1. Os sistemas escolhidos foram analisados através das técnicas de microscopia de luz polarizada (MLP), espalhamento de raios-X a baixo ângulo (SAXS), análise reológica, e avaliação da concentração letal média (CL50) frente a larvas do Ae. aegypti. O PPG-5 CETETH-20 exibiu CMC= 0,2 g/ L, PPG-5 CETETH-20:AO 1:1 CMC= 0,077 g/ L e 2:1 CMC= 0,0578 g/ L, indicando que existe um sinergismo entre o tensoativo e o cotensoativo para baixar a tensão superficial. Foram observadas quatro regiões distintas no diagrama 2:1, cristal líquido (CL), emulsão, microemulsão (ME) e separação de fases, sendo que no diagrama 1:1 não foi observada região de cristal líquido. Através das micrografias obtidas por MLP, foi possível diferenciar os sistemas isotrópicos, como MEs dos anisotrópicos, como CLs lamelares e hexagonais. As medidas de SAXS confirmaram as estruturas visualizadas por MLP, exibindo picos largos e de baixa intensidade para MEs (todas do diagrama 1:1 e seis amostras no diagrama 2:1), transição de fase e razão entre os picos de CL lamelar de 1:2:3 e 1:√3:√4 para o hexagonal. O estudo das propriedades reológicas demonstrou que os sistemas MEs e transição de fase são newtonianos e os CLs são não-newtonianos e que o aumento da fase aquosa aumenta o componente elástico dos CL. Para a atividade larvicida, as amostras A3 (15% A/ 5% OECS/ 80% PPG-5 CETETH-20: AO) e A4 (20% A/ 5% OECS/ 75% PPG-5 CETETH-20: AO) do diagrama 2:1 demonstraram CL50 6,55 ppm e 5,93 ppm, respectivamente, indicando que a microestrutura presente nesses sistemas corroborou para o aumento da solubilidade do óleo em meio aquoso. Desse modo, pode-se concluir que foram obtidos precursores de fase líquido-cristalina com potencial uso contra as larvas de Ae. aegypti.

Mutations of three genes encoding amyloid precursor protein (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) have been shown to reliably result in familial early-onset Alzheimer's disease (FAD); a rare, but catastrophic, subtype of Alzheimer's disease (AD) marked by symptom emergence before age 65 as well as accelerated cognitive deterioration. The current study represents the first known meta-analysis on the association of APP, PSEN1 or PSEN2 on neurocognitive variables. A total of 278 FAD mutation-carriers (FAD-MC) and 284 cognitively healthy non-mutation-carriers (NC) across 10 independent investigations meeting inclusion criteria were chosen for the current meta-analysis (random effects design). Findings revealed an overarching trend of poorer performance by FAD-MC individuals compared to NC individuals across the majority of cognitive domains identified. Significant differences in effect sizes suggested FAD-MC individuals exhibited worse performance on measures of attention, explicit memory, fluency, primary memory, verbal, and visuospatial functioning. Findings indicative of differential sensitivity to cognitive domain impairments across FAD-MC and NC groups inform neuropsychological descriptions of individuals in preclinical phases of FAD.

No description available.

Understanding the lignin effect and related structural parameters relevant to the recalcitrance of the plant cell wall and the individual and cooperative effects on enzymatic saccharification are vital for improving current processing and conversion methods for cellulosic biofuels. Data were collected from several pretreatment technologies (Hot-water, organo-solv, lime, lime-oxidant, dilute acid, and dilute acid-oxidant pretreatments) on cellulose ultrastructure, partial delignification followed by dilute acid pretreatment, dilute acid pretreatment of enzymatic isolated lignin, and melt rheology test of organo-solv lignin. Results showed minimal cellulose ultrastructural changes occurred due to lime and lime-oxidant pretreatments, which however especially at short residence time displayed relatively high enzymatic glucose yield. Dilute acid and dilute acid-oxidant pretreatments resulted in the largest increase in cellulose crystallinity, para-crystalline, and cellulose-Iβ allomorph content as well as the largest increase in cellulose microfibril or crystallite size. Organo-solv pretreatment generated the highest glucose yield, which was accompanied by the most significant increase in cellulose microfibril or crystallite size and decrease in relatively lignin contents. Lignin acted as a barrier which restricted cellulose crystallinity increase and cellulose crystallite growth during dilute acid pretreatment, and that partial delignification instead of complete lignin removal during DAP would benefit the increase of sugar yield. Furthermore, a deeper understanding of the structural change of lignin in the absence of cellulose-hemicellulose matrix during dilute acid pretreatment confirmed that delignification had the most beneficial effect in poplar, but for switchgrass was the xylan removal. In addition, investigation on the structural change of organo-solv lignin during melt rheology test indicated that high purity lignin isolated from plant biomass with the lowest S/G (syringyl/guaiacyl) ratios will exhibit superior processing performance characteristics to produce high-quality carbon fibers. These findings can aid both in the development of improved enzymes that contain activities to decompose recalcitrant structures and in the design of various processing conditions that efficiently convert specific biomass feedstock into sugars. They can also help in the design of new chemical modifications on lignin and innovative biosynthesis strategies for producing linear-fiber-forming lignin with high-performance.

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

Heat shock proteins function as molecular chaperones which help protein folding and prevent protein aggregation. My study shows that celastrol, a pharmacological compound capable of up-regulating the levels of heat shock proteins, inhibits cell death and protein aggregation caused by expanded polyglutamine containing protein, and the protective effects of celastrol are dependent on heat shock factor 1. These results suggest the potential of celastrol as a therapeutic agent in the treatment of polyglutamine diseases. Sumoylation is a protein modification which plays diverse roles in regulating the target proteins. My study shows that lamin A is a target of protein sumoylation, and two lamin A mutants associated with familial dilated cardiomyopathy, E203G and E203K, exhibit decreased sumoylation. My results also indicate that sumoylation is important for the normal localization of lamin A, and support a role for altered sumoylation in the underlying molecular mechanism of cardiomyopathies associated with the E203G/E203K lamin A mutations. In the third project, my results show that amyloid precursor protein is another target of SUMO modification, and sumoylation of amyloid precursor protein reduces the levels of amyloid β aggregates, which are the primary causative factor for Alzheimer’s disease. My results provide a new mechanism for the generation of amyloid β, and indicate the potential of up-regulating activity of the cellular sumoylation machinery as an approach against Alzheimer’s disease. My results also provide the first demonstration that SUMO E2 enzyme exists in the lumen of the endoplasmic reticulum, extending the sub-cellular reach of sumoylation to include the regulation of proteins in secretory pathways.

Spreading plays an important role in coating, lubrication, printing and etc. During the spreading process, a liquid thin film forms prior to the expansion of a liquid drop. This thin film is called a precursor film. It not only changes the spreading mechanism, but impacts the wettability of a liquid. Early studies on the precursor films showed the films were stacked in a terraced structure, and the radius of each layer of the films was proportional to the square root of time. Optical techniques such as ellipsometry, X-ray diffraction and X-ray reflectivity solved the conformations of liquid molecules at the interfaces. However, the conformations of the interfacial molecules have rarely been correlated with their positions at the interface. In addition, the properties of the precursor films have not been fully studied yet. In this dissertation, two kinds of organic compounds, hexatriacontane (C36) and 1-butyl-3-methylimidazolium ([Bmim][Cl]), are proposed to be spread over octadecyltrichlorosilane partially degraded (OTSpd) patterned surfaces. Once organic molecules flow over such OTSpd surfaces, the liquids are limited within the patterned area. Characterized by atomic force microscopy (AFM), the structures and chemical identities and the formation mechanism of the precursor films are resolved thereafter. The precursor films formed by both compounds, C36 and [Bmim][Cl], were observed in a bilayer structure in that the molecules close to the solid substrate had different orientation from the molecules close to the air. They were called parallel layers and standing-up layers, respectively. The parallel layers of C36 formed prior to the standing-up layers through the vapor phase transport. In addition, the parallel layers were found more stable thermodynamically and the standing-up layers were more stable mechanically. The frictional study of C36 showed the standing-up layers could hold 0.49GPa pressure. The orientation of [Bmim][Cl] molecules were impacted by the polarities of the solid substrates. The achievements in this dissertation not only resolve the properties of the precursor films of two organic compounds, but provide a general method for the further studies of the precursor films.

La maladie d’Alzheimer est une maladie neurodégénérative, elle représente 70% des formes de démences et affecte près de 860 000 personnes en France. Cette maladie est caractérisée par deux lésions neuropathologiques : les Dégénérescences neurofibrillaires et les Plaques séniles. Ces dernières sont principalement constituées de peptides amyloïdes (A&#946;) résultant du clivage d’une protéine membranaire appelée Précurseur du peptide amyloïde (APP). L’étude des formes familiales monogéniques a montré que des mutations des gènes de l’APP et des Présénilines 1 et 2 conduisaient systématiquement à une augmentation de la production d’A&#946;. Cette observation a permis l’élaboration de la cascade amyloïde plaçant le métabolisme de l’APP au centre du processus physiopathologique. Même si aujourd’hui ce métabolisme commence à être relativement bien connu, plusieurs zones d’ombres subsistent encore. Dans l’optique de caractériser de nouveaux acteurs intervenant dans ce métabolisme, nous avons émis une hypothèse qui repose sur deux constatations : (i) les protéines impliquées dans l’étiologie de la maladie sont différentiellement exprimées entre les cerveaux des patients et ceux des témoins (ii) dans le cerveau, de nombreuses métalloprotéases participent aux même mécanismes que l’APP (adhésion cellulaire, neuroinflammation, plasticité neuronale...), certaines sont aussi directement actrices du métabolisme de l’APP en tant qu’&#945;-sécrétase (ADAM9, ADAM10 et ADAM17) ou en dégradant l’A&#946; (NEP, IDE, MMP2, MMP3 et MMP9). Nous avons donc supposé que les métalloprotéases présentant une différence d’expression entre le tissu cérébral des malades et celui des témoins soient des candidates intéressantes pour moduler le métabolisme et le trafic de l’APP. Une première analyse transcriptomique par biopuce, à partir d’ARN totaux issus des cerveaux de 12 malades et de 12 témoins, nous a permis d’identifier quatre métalloprotéases présentant une différence d’expression significative (p<10-5) : ADAMTS16, ADAM17, ADAM30 et ADAM33. Nous avons cherché à confirmer ce résultat par une autre technologie sur un plus grand nombre d’échantillons (malades n=52 et témoins n=42). Seules ADAM30 et ADAM33 ont pu être validées. Nous avons également pu observer que l’expression d’ADAM30 dans le tissu cérébral des malades est inversement proportionnelle à la quantité d’A&#946;42 déposée dans la parenchyme (A&#946;42 la forme d’A&#946; la plus neurotoxique). De plus, au niveau cérébral, l’expression d’ADAM30 est restreinte aux neurones, cellules sièges du métabolisme de l’APP. Nous avons donc sélectionné ADAM30 comme intervenante potentielle dans le métabolisme de l’APP. Pour tester notre hypothèse, nous avons sous- et sur-exprimé ADAM30 dans deux modèles cellulaires différents. Nous avons mis en évidence que la sur-expression d’ADAM30 entraîne une diminution de l’ensemble des produits du métabolisme de l’APP. En mutant le site catalytique de cette protéase, nous avons remarqué que cette action sur le métabolisme de l’APP est dépendante de cette activité catalytique. De manière cohérente, une sous-expression d’ADAM30 entraîne une augmentation de l’ensemble des produits du métabolisme de l’APP. En utilisant les inhibiteurs alcalisant, nous avons démontré que l’effet d’ADAM30 sur le métabolisme de l’APP met en jeu la dégradation par le lysosome. Des expériences d’immunofluorescence ont attesté qu’ADAM30 est localisée dans le réticulum endoplasmique et l’appareil de Golgi et qu’elle co-localise fortement avec l’APP dans ces organites. Au vu des résultats obtenus durant ces quatre années, nous pensons qu’ADAM30 pourrait être une protéine clé de la régulation de l’APP en inhibant son acheminement jusqu’à la membrane plasmique et en favorisant sa dégradation par le lysosome. [...] / Alzheimer’s disease (AD) is the most common neurodegenerative disorder of the old age, characterized by the presence of two major neuropathological features : neurofibrillary tangles and senile plaques. These plaques are composed of the A&#946; peptides cleavage product of the amyloid precursor protein (APP). Proteolytic processing of APP is modulated by the action of enzymes &#945;-, &#946;- and &#947;-secretases with the latter two mediating the amyloidogenic pathway. Suggesting that processing of APP is a key step in the pathology of AD. However, even if extensively studied, this APP metabolism is still not fully characterized. With this background, we postulate that the characterization of new actors of the APP metabolism might help for a more subtle understanding of this APP metabolism and trafficking. We focused on the ADAMs and related proteins with the hypothesis that ADAMs and related proteins, under- or over-expressed in the brain of AD cases compared with the one of controls, may be of particular interest. Beyond the obvious implication of several ADAMs as &#945;-secretases, this hypothesis was also driven by several observations : (i) ADAMs have been involved in numerous biological processes including brain development, plasticity and repair as APP; (ii) several metalloproteases (MMP-2, -3 and -9) have been described to degrade A&#946; peptides. Using microarray to screen the expression of 117 ADAMs and MMPs was analyzed using total RNA extracted from cerebral tissue of 12 AD cases and 12 controls. We observed that 4 ADAMs were differentially expressed. We first confirmed that the ADAM30 expression was decreased in AD brains and we observed that ADAM30 under-expression was correlated with an increase in A&#946;42 deposition in AD brains. Consistently, over-expression of ADAM30 led to decrease APP metabolism and as a consequence, A&#946; secretion in two different cell lines (Moreover, under-expressed ADAM30 increases APP processing and A&#946; generation). This modification of the APP metabolism was directly linked to the ADAM30 catalytic properties. Our data suggest that catalytic activity of ADAM30 takes an important place in APP processing in a lysosome dependent manner and AD pathophysiological process.

Background: Current research has demonstrated that aspirin and fish oil (EFA) increase plasma levels of specialized pro-resolution molecules (SPMs). This study investigates their effects on SPM precursor pools in platelet rich fibrin (PRF). Methods: Twenty healthy volunteers were randomly assigned to take aspirin; EFA or aspirin and EFA. Four hours later, SPM precursor levels were quantified using combined Liquid Chromatography tandem mass spectrometry. The differences between the groups: Aspirin (yes or no), EFA (yes or no), were analyzed by ANCOVA, testing for group differences after covarying out the baseline value. Results: There were 4 significant interactions, 1 with an aspirin effect, 2 with an EFA effect, and 64 with no difference between the groups. The significant interaction effect was found for the following lipidome: LPE(20:4), LPI(16:1), LPI(18:1), and LPI(20:3). Aspirin decreased the LPG(16:4) levels, and EFA decreased the LPE(22:5) and PG(16:0/18:0) lipidomes. Conclusions: Some SPM precursor pools in PRF were increased following supplementation.

Neurons are generated from unspecialized neural precursor cells (NPCs) in a process termed neurogenesis. This neuronal development continues throughout life in the ventricular zone (VZ) of the lateral ventricles, and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. NPCs undergo a complex and highly regulated set of behaviours in order to ultimately integrate into the existing brain circuitry as fully functional neurons. Recently the pannexin (Panx) large-pore channel proteins were discovered. One family member, Panx1 is expressed in the nervous system in mature neurons, and acts as an ATP release channel in various cell types throughout the body. Post-natal NPCs are responsive to ATP via activation of purinergic receptors, which modulate a variety of NPC behaviours. I therefore investigated the hypothesis that Panx1 was expressed in post-natal VZ NPCs, where it functioned as an ATP release channel and regulated neuronal development. In the course of my studies, I found that Panx1 positively regulated NPC proliferation and migration, and negatively regulated neurite outgrowth in vitro. Using an NPC-specific Panx1 knock-out strategy, I showed that Panx1 expression was required for maintenance of a consistent population of VZ NPCs in vivo in both healthy and injured brain. Together these data indicated that Panx1 directed NPC behaviours associated with neuronal development both in vitro and in vivo. To further understand the molecular underpinnings of this regulation, I examined the Panx1 interactome, and uncovered a novel association with collapsin response mediator protein 2 (Crmp2). Functional studies suggested that this interaction likely was at least in part responsible for Panx1’s negative impact on neurite outgrowth. Overall, my results represent important novel findings that contribute to our understanding of post-natal neuronal development and the molecular function of Panx1 within the brain. / Graduate / 0317 / 0379 / leighws@uvic.ca