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This dissertation proposes that while traditional cognitive psychology literature suggests that cognitive function decreases with age, these decreases are dependent on the types of testing being performed. While traditional cognitive tests of memory and processing speed show declines associated with age, this research suggests these declines are not robust across all types of learning. The coming pages present four studies aimed at furthering our understanding of how different age cohorts of consumers learn about products in active and complex marketplaces. Study one reveals an age advantage associated with learning experientially; an interesting and somewhat surprising result that warrants further investigation given the rapid rate at which populations are aging. The additional studies presented here begin that investigation through the application of several psychological theories. This research explores increased vigilance associated with the security motivation system (based on the principles of evolutionary psychology), the possible impact of mortality salience through the application of Terror Management Theory and a positive correlation between age and cognitive control, as possible explanations. / Business Administration/Marketing

The purpose of this project is to find a mathematical model to describe the vision profile of patients after treatment for choroidal neovascularization. In this model the dependent variable is the level of vision which will be predicted by time after treatment and a number of other variables measured before treatment. A standard multiple regression analysis is used to find significant predictor variables, to investigate interactions and an appropriate transformation. To take the correlation of observations on the same patient into account a linear mixed effects model is fitted. Finally the usefulness of a nonlinear mixed effects model is investigated. / Thesis / Master of Science (MS)

Age-related macular degeneration (AMD) is one of the leading causes of blindness in adults over the age of 60. Currently, at least 11 million patients in the United States have some form of macular degeneration and this number is projected to grow as the population ages. The more severe form of the disease – neovascular (wet) AMD, is characterized by intraocular neovascularization, inflammation, and retinal damage; however, the disease progression can be deterred through intraocular injections of anti-angiogenic agents. The complications and burden that arise from repetitive injections as well as the difficulty posed by targeting the posterior segment of the eye make this an interesting territory for the development of novel drug delivery systems. New methods for drug delivery are being investigated exploring the use of nanoparticles and other polymeric materials. The goal of this project is to study the potential use of poly(lactide-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles in thermoreversible gels as localized sustained intraocular drug delivery. We prepared stable and reproducible corticosteroid-encapsulated nanoparticles in thermoreversible gels to inhibit vascular endothelial growth factor (VEGF) overexpression characteristic of neovascular AMD. We characterized the drug delivery system by obtaining size, shape, and drug encapsulation data. We also demonstrated that the polymer could be injected into the vitreous as a solution and transition to a gel phase based on the temperature difference between regular indoor environment and the vitreous body. The drug delivery system was tested on human retinal pigment epithelial cells (ARPE-19), for cytotoxicity, uptake and VEGF expression. We also examined the drug delivery system's ability to mitigate the disease progression in a mouse model of choroidal neovascularization (CNV). The effect on blood vessel area was shown and the changes in the mRNA expression of angiogenesis mediators were analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR). These results indicate that the proposed drug delivery systems has the promise to be developed for retinal diseases, involving CNV, including neovascular AMD. Further studies are warranted in developing this promising intraocular drug delivery system for wet AMD and similar ophthalmic diseases. / Ph. D.

Yes / We investigated whether perceptual learning could be used to improve peripheral word identification speed. The relationship between the magnitude of learning and age was established in normal participants to determine whether perceptual learning effects are age invariant. We then investigated whether training could lead to improvements in patients with age-related macular degeneration (AMD). Twenty-eight participants with normal vision and five participants with AMD trained on a word identification task. They were required to identify three-letter words, presented 10° from fixation. To standardize crowding across each of the letters that made up the word, words were flanked laterally by randomly chosen letters. Word identification performance was measured psychophysically using a staircase procedure. Significant improvements in peripheral word identification speed were demonstrated following training (71% ± 18%). Initial task performance was correlated with age, with older participants having poorer performance. However, older adults learned more rapidly such that, following training, they reached the same level of performance as their younger counterparts. As a function of number of trials completed, patients with AMD learned at an equivalent rate as age-matched participants with normal vision. Improvements in word identification speed were maintained at least 6 months after training. We have demonstrated that temporal aspects of word recognition can be improved in peripheral vision with training across a range of ages and these learned improvements are relatively enduring. However, training targeted at other bottlenecks to peripheral reading ability, such as visual crowding, may need to be incorporated to optimize this approach. / This work was supported by a National Institute of Health Research (NIHR) Post Doctoral Fellowship awarded to ATA, an Age UK Studentship awarded to AJB, and a Wellcome Trust Career Development Fellowship awarded to BSW. This article presents independent research funded by the NIHR.

yes / Microperimetry, also referred to as fundus perimetry or fundus-driven perimetry, enables simultaneous acquisition of visual sensitivity and eye movement data. We present sensitivity data collected from 60 participants with normal vision using gaze-contingent perimetry. A custom designed spatially dense test grid was used to collect data across the visual field within 13° of fixation. These data are supplemental to a study in which we demonstrated a spatial interpolation method that facilitates comparison of acquired data from any set of spatial locations to normative data and thus screening of individuals with both normal and non-foveal fixation (Denniss and Astle, 2016)[1].

C1QTNF5 is a 25kDa short chain collagen of unknown function which is mutated in late-onset retinal macular degeneration (L-ORMD). L-ORMD is an autosomal dominant disease characterised by sub-retinal pigment epithelial deposits leading to photoreceptor death and visual loss and shows several similarities to age-related macular degeneration (AMD). A Tyr402His polymorphism in complement factor H (CFH), a regulatory protein in the innate immune system, has been associated with increased risk of AMD. C1QTNF5 and CFH are both expressed and secreted by the retinal pigment epithelium (RPE) which supports photoreceptors and is responsible for phagocytosis of shed rod photoreceptor outer segments (ROS). The properties of the normal C1QTNF5 and disease-associated Ser163Arg mutation were examined in detail, including protein characterisation, cellular processing and function. Recombinant wild type and mutant C1QTNF5 were produced and their multimerisation and solubility functions compared. Both proteins were found to be soluble and to form similar multimeric species which were resistant to reducing conditions, as seen in other short chain collagens. Due to the similarities between LORMD and AMD, a proposed interaction between C1QTNF5 and CFH was investigated. CFH is composed of 20 short consensus repeats (SCR) and interactions were confirmed between C1QTNF5 and both CFH and SCR modules 7-8 and 19-20. CFH showed a greater affinity for mutant C1QTNF5 compared with wild type on the basis of surface plasmon resonance assays. Stably transfected RPE-derived cell lines were created which expressed either wild type or mutant C1QTNF5. Both proteins were found to be secreted and showed similar cellular processing with no evidence of aggregation or retention of the mutant protein within the endoplasmic reticulum. In order to investigate C1QTNF5 function, phagocytosis of ROS by the stably transfected cell lines was carried out. Cells expressing wild type C1QTNF5 showed greater ROS phagocytosis compared with mutant C1QTNF5-expressing or untransfected cells. Addition of anti-C1QTNF5 antibody increased ROS phagocytosis further. In summary, it is proposed that wild type and mutant C1QTNF5 are secreted by the RPE where they interact with CFH. C1QTNF5 is also shown to have a role in ROS phagocytosis, with mutation in C1QTNF5 affecting phagocytosis efficiency, which may contribute to sub-RPE deposit formation. The results suggest that CFH may also be involved in this process, suggesting a common pathogenic pathway between L-ORMD and AMD.

<p>Complement factor H (CFH) is a major susceptibility gene for age-related macular degeneration (AMD); however, its impact on AMD pathobiology is unresolved. Here, the role of CFH in the development of AMD pathology in vivo was interrogated by analyzing aged Cfh+/- and Cfh-/- mice fed a high fat, cholesterol-enriched diet. Strikingly, decreased levels of CFH led to increased sub-retinal pigmented epithelium (RPE) deposit formation, specifically basal laminar deposits, following high fat diet. Mechanistically, our data show that deposits are due to CFH competition for lipoprotein binding sites in Bruch’s membrane. Interestingly and despite sub-RPE deposit formation occurring in both Cfh+/- and Cfh-/- mice, RPE damage accompanied by loss of vision occurred only in old Cfh+/- mice. We demonstrate that such pathology is a function of excess complement activation and C5a production, associated with monocyte recruitment, in Cfh+/- mice versus complement deficiency in Cfh-/- animals. Due to the CFH dependent increase in sub-RPE deposit height we interrogated the potential of CFH as a novel regulator of Bruch’s membrane lipoprotein binding and show, using human Bruch’s membrane explants, that CFH removes endogenous human lipoproteins in aged donors. Interestingly, although the CFH H402 variant shows altered binding to BrM, this does not affect its ability to remove endogenous lipoproteins. This new understanding of the complicated interactions of CFH in AMD-like pathology provides an improved foundation for the development of targeted therapies for AMD.</p> / Dissertation

Ackmann, Charlotte Osmotische Induktion des Komplementfaktors C9 in retinalen Pigmentepithelzellen Universität Leipzig, Dissertation 98 Seiten, 208 Literaturangaben, 28 Abbildungen, 8 Tabellen Die altersbedingte Makuladegeneration (AMD) ist die häufigste Ursache für Erblindung bei Erwachsenen in den industrialisierten Ländern. Die AMD ist unter anderem eine chronisch entzündliche Erkrankung, bei der die Aktivierung der alternativen Komplementkaskade eine Rolle spielt. Daneben erhöht Bluthochdruck, der auch durch eine salzreiche Ernährung getriggert wird, das Risiko an einer AMD zu erkranken. Untersucht wurde die Genexpression des Komplementfaktors C9 unter verschiedenen pathologischen Bedingungen in humanen retinalen Pigmentepithel (RPE)-Zellen sowie deren Wirkung auf die physiologischen Eigenschaften der Zellen. Gezeigt wird, dass die Expression des C9 Gens in humanen RPE-Zellen spezifisch durch Hyperosmolarität, Hypoxie und oxidativen Stress induziert wird. Die Menge an C9 Protein wurde durch Hyperosmolarität leicht aber signifikant erhöht. Die hyperosmotische Induktion der C9 mRNA ist abhängig von der Aktivierung der Signalproteine p38 MAPK, ERK1/2, JNK, PI3K, sowie der Transkriptionsfaktoren STAT3 und NFAT5 während für die Hypoxie-induzierte C9 mRNA Expression nur eine Beteiligung des Transkriptionsfaktors STAT3 nachgewiesen wurde. Die Aktivierung verschiedener Signalwege durch Hyper-osmolarität und Hypoxie lässt vermuten, dass eine hohe Kochsalzaufnahme auch unter normoxischen Verhältnissen die Eigenschaften RPE-Zellen verändert. Hyperosmolarität hemmt die Proliferation und Migration der RPE-Zellen, während chemische Hypoxie nur die Proliferationsrate verringert. Die Wirkung einer erhöhten extrazellulären NaCl-Konzentration auf die C9 mRNA Expression wird über zwei Mechanismen vermittelt: über die Erhöhung der extrazellulären Osmolarität und über die Veränderung des NaCl-Gradienten über der Plasmamembran. Die NaCl Wirkung über den veränderten NaCl-Gradienten lässt vermuten, dass eine übermäßige Aufnahme von Kochsalz nicht nur über die Erhöhung des Blutdruckes die Pathogenese der AMD stimuliert, sondern dass Kochsalz auch eine direkte stimulierende Wirkung auf RPE-Zellen besitzt. Diese Vermutung könnte erklären, weshalb hoher Blutdruck ein Risikofaktor der AMD ist, aber Medikamente zur Behandlung des Bluthochdruckes das Risiko der AMD nicht verändert.

<p>Age-related macular degeneration is one of the leading causes of vision loss in the world. While identification of various environmental risk factors including but not limited to smoking, ethnicity, and diet have been reported to contribute to the complex etiology of AMD, age and genetics remain the largest susceptibility factors in its pathogenesis. Initially, with the identification of the common Y402H variant in CFH, approximately 35% of the genetic determinants of AMD had been identified with the majority remaining unknown. Therefore, we set forth to A) identify additional AMD susceptibility genes that contribute to AMD through the use to next generation sequencing technologies and B) to assess associated alleles for pathogenicity in the attempt to interpret their functional contributions to AMD outcome as observed via patient serum and zebrafish analysis. In doing such, we have identified both common and rare variants that contribute to the heritability of AMD. Additionally, we report one of the first instances of a rare variant significantly increasing disease onset and a gene with increased rare mutational burden in AMD patients. All together adding to our understanding of the genetics of AMD and potentially leading to putative therapeutic targets.</p> / Dissertation