La formation de néo-vaisseaux sanguins est un processus impliqué dans de nombreuses pathologies, telles que le développement de carcinomes cutanés et la néo-vascularisation choroïdienne caractéristique de la forme exsudative de la dégénérescence maculaire liée à lâge (DMLA). Dans ces deux cas, lactivation du réseau vasculaire est un facteur de mauvais pronostic. Lanalogie entre ces deux pathologies est renforcée par le développement récent dapproches thérapeutiques anti-angiogènes. Ces approches ciblent principalement le VEGF et les molécules associées. Malgré lefficacité de ces molécules sur la pathologie ciblée, leur administration systémique engendre des effets secondaires non négligeables. Notre travail a pour but détudier limplication dautres acteurs moléculaires dans ces pathologies, en vue de développer des stratégies thérapeutiques alternatives ou complémentaires. Parmi les principales molécules impliquées lors de langiogenèse, les protéases et leurs inhibiteurs sont des cibles potentielles pour le développement de nouveaux traitements. Il était initialement admis que les protéases (MMPs, protéases à sérine) sont des facteurs pro-angiogènes et leurs inhibiteurs (TIMPs, PAI-1) des facteurs anti-angiogènes. Dans ce contexte, lhypothèse thérapeutique évidente était dinhiber les protéases et de protéger ou dactiver leurs inhibiteurs. Cependant, lorsque nous avons entamé ce travail, ce concept a été remis en question. En effet, un niveau élevé de PAI-1 a été détecté dans de nombreux cancers et représente un facteur de mauvais pronostic. Par ailleurs, les inhibiteurs des MMPs nont présenté aucun effet lors dessais cliniques, certains stimulant même la croissance tumorale. Il est important de noter que ces premiers inhibiteurs étaient des inhibiteurs à large spectre bloquant laction non seulement des MMPs, mais aussi des membres de familles proches. Une détection fine des rôles joués par les MMPs et linhibiteur PAI-1 sest avérée indispensable. Nous avons, dès lors, focalisé notre travail sur deux thèmes : létude de PAI-1 et létude du rôle individuel de quelques MMPs. Il a précédemment été démontré que linhibiteur PAI-1 exerce un rôle pro-angiogène lors du développement de carcinomes cutanés et de néo-vascularisation choroïdienne. PAI-1 exerce donc un effet paradoxal et complexe sur langiogenèse. Bien que le rôle de PAI-1 au cours de langiogenèse bourgeonnante était bien documenté, son implication au cours de la vasculogenèse nétait pas connue. Nos résultats démontrent que le développement des carcinomes cutanés nécessite la migration des cellules stromales adjacentes aux cellules tumorales. Par contre, la néo-vascularisation choroïdienne, également dépendante de PAI-1, requiert le recrutement des cellules issues de la moelle osseuse. Publications 1 et 2. La seconde partie de notre travail est consacrée aux métalloprotéinases matricielles. Nos résultats montrent les rôles opposés ou synergiques des MMPs. Les MMP-2 et -9 sont des protéases pro-angiogènes agissant de concert au cours de linvasion des carcinomes. A lopposé, la MMP-19 exerce une fonction anti-angiogène et nos travaux suggèrent que cette MMP contribuerait à la stabilité des vaisseaux matures et au maintien physiologique des tissus, son expression étant diminuée lors de linvasion tumorale. Publications 3, 4 et 5.

Current anti-VEGF biologics, such as bevacizumab and VEGF trap, have been successfully used as therapeutic agents for cancer and age-related macular degeneration (AMD). Since these strategies target VEGF systemically, their toxicity profile, including proteinuria and thromboembolic events, and need for frequent eye injections in AMD treatment, prevail. Therefore, the aim of this PhD thesis was to generate novel anti-VEGF biologics that inhibit VEGF activity specifically at the desired target site. Two classes of biologics were engineered that simultaneously bind VEGF and either: 1) the extracellular matrix (ECM) or 2) target-site specific antigens. The first subgroup, “sticky-traps”, is composed of VEGF trap linked to a sequence of hydrophobic amino acids, with affinity for heparin sulfate proteoglycans of the ECM. The second subgroup, “lassos”, is composed of a C-terminus positioned form of VEGF trap linked to single-chain variable domain antibodies specific for either HER2 (HER2/V lasso) or fibronectin extra domain B (EDB; EDB/V lasso), expressed on breast cancer cell surfaces or in the vascular bed of solid tumours, respectively. ii Using a novel transgenic method, piggyBac transposons, biologics were expressed in transgenic cancer cell lines in a doxycycline inducible manner. They were shown to inhibit VEGF activity and also retain the native function of their constituent domains. Specifically, the sticky-traps adhered to the ECM and the HER2/V lasso inhibited the proliferation of HER2 positive cancer cell lines. Sticky-traps as well as lassos were able to inhibit or delay tumour growth of A-673, Pc-3, SKOV-3 and HT-29 xenografts. In contrast to soluble VEGF trap, sticky-traps were retained at the tumour site and were undetectable in the circulation. Moreover, sticky-traps, in contrast to VEGF trap, did not delay wound healing and regression of trachea blood vessels. Furthermore, transgenic studies indicated that HER2/V lasso is more effective compared to anti-HER2 Ab and VEGF trap used alone or in combination. These novel classes of antiangiogenic molecules could be advantageous in a clinical setting. Using the principles established in my PhD thesis work, similar dual function biologics can be designed for inhibition of other molecules with disease relevance.

Current anti-VEGF biologics, such as bevacizumab and VEGF trap, have been successfully used as therapeutic agents for cancer and age-related macular degeneration (AMD). Since these strategies target VEGF systemically, their toxicity profile, including proteinuria and thromboembolic events, and need for frequent eye injections in AMD treatment, prevail. Therefore, the aim of this PhD thesis was to generate novel anti-VEGF biologics that inhibit VEGF activity specifically at the desired target site. Two classes of biologics were engineered that simultaneously bind VEGF and either: 1) the extracellular matrix (ECM) or 2) target-site specific antigens. The first subgroup, “sticky-traps”, is composed of VEGF trap linked to a sequence of hydrophobic amino acids, with affinity for heparin sulfate proteoglycans of the ECM. The second subgroup, “lassos”, is composed of a C-terminus positioned form of VEGF trap linked to single-chain variable domain antibodies specific for either HER2 (HER2/V lasso) or fibronectin extra domain B (EDB; EDB/V lasso), expressed on breast cancer cell surfaces or in the vascular bed of solid tumours, respectively. ii Using a novel transgenic method, piggyBac transposons, biologics were expressed in transgenic cancer cell lines in a doxycycline inducible manner. They were shown to inhibit VEGF activity and also retain the native function of their constituent domains. Specifically, the sticky-traps adhered to the ECM and the HER2/V lasso inhibited the proliferation of HER2 positive cancer cell lines. Sticky-traps as well as lassos were able to inhibit or delay tumour growth of A-673, Pc-3, SKOV-3 and HT-29 xenografts. In contrast to soluble VEGF trap, sticky-traps were retained at the tumour site and were undetectable in the circulation. Moreover, sticky-traps, in contrast to VEGF trap, did not delay wound healing and regression of trachea blood vessels. Furthermore, transgenic studies indicated that HER2/V lasso is more effective compared to anti-HER2 Ab and VEGF trap used alone or in combination. These novel classes of antiangiogenic molecules could be advantageous in a clinical setting. Using the principles established in my PhD thesis work, similar dual function biologics can be designed for inhibition of other molecules with disease relevance.

Previous research has consistently shown associative deficits in older adults learning and memory (Chalfonte & Johnson 1996; Naveh-Benjamin, 2000; Naveh-Benjamin, Hussain, & Bar-On 2003) that are related to decreases in hippocampal function (Driscoll et al., 2003; Mitchell, Johnson, Raye, & D’Esposito, 2000). However, older adults learn certain simple predictive relationships between events (Mutter & Williams, 2004) that involve basal ganglia dependent error-driven learning. The goal of the current study was to determine whether error-driven learning could reduce the age-related associative deficits that are associated with hippocampal decline. The results did not support the idea that error-driven learning enhanced older adults’ associative memory, although our study supported normal error-driven processing in older adults. Our study confirms prior findings showing that age differences in associative memory are greater following an error-driven learning task than following an observation learning task (Schmitt-Eliassen, Ferstl, Wiesner, Deuschl, & Witt, 2007; Shohamy et al., 2004). Therefore, the results of the study did not support enhanced associative memory for older adults due to errordriven processing.

Eine lokale Aktivierung des Komplementsystems im RPE ist ein pathogener Faktor der AMD. Neben der Wirkung von angiogenen Faktoren wie VEGF könnte eine Aktivierung des Blutgerinnungssystems im RPE dazu beitragen, dass sich aus einer trockenen eine feuchte AMD entwickelt. Dies könnte auf mehreren Ebenen geschehen: Gerinnungsfaktoren könnten die Expression der Komplementfaktoren und der angiogenen Faktoren regulieren sowie Wirkungen auf die Proliferation und Migration der RPE-Zellen besitzen. Eine Stimulierung der Proliferation und Migration der RPE-Zellen trägt zur Ausbildung von CNV-Membranen bei. Es ist aber bis jetzt nichts darüber bekannt, ob RPE-Zellen Faktoren des Blutgerinnungssystems exprimieren und ob z.B. Thrombin (als zentrale Protease des Blutgerinnungssystems) die Genexpression von Komplementfaktoren und von VEGF im RPE beeinflusst. Die Ziele der vorliegenden Dissertation waren daher: ● Nachweis der mRNA-Expression von Blutgerinnungs- und Komplementfaktoren im RPE; ● Nachweis der Wirkung von Thrombin auf die Expression von VEGF und von Komplementfaktoren, sowie auf die Proliferation und Migration der RPE-Zellen; und ● Nachweis der Wirkung der Komplementfaktoren C5a und C9 auf die Sekretion von VEGF und die Proliferation und Migration der RPE-Zellen.

It is widely held among cognitive aging researchers that older adults are at a disadvantage with respect to the division of attention between two or more concurrent tasks. Some researchers have attributed dual-task performance decrements to reduced processing speed with age while others have attributed declines in dual-task performance to the reduced efficiency of task coordination and control processes. Few researchers, however, have considered the possibility that age-related differences in dual-task performance may be related to underlying differences in the learning mechanisms supporting component task performance. Three studies were conducted which differed in the type of single-task training provided to young and old adult participants: Consistently mapped (CM), variably mapped (VM) and attenuated priority (AP) training. Skilled dual-task performance was then assessed as a function of both component task learning and age through a) the examination of initial and end-level skilled dual-task performance, b) transfer of learning to novel task combination and c) retention capability. It was predicted that type of component task training would moderate age-related differences in skilled dual-task performance. The results were confirmatory, however, were not completely consistent with initial predictions.

Age-related declines in hearing abilities are common and can be attributed to changes in the peripheral and central levels of the auditory system. Although central auditory processing is enhanced in younger musicians, the influence of lifelong musicianship on age-related decline in central auditory processing has not yet been investigated. Therefore, the purpose of this dissertation was to investigate whether lifelong musicianship can mitigate age-related decline in central auditory processing. In the first experiment, age-related declines on four hearing assessments were compared between musicians and non-musicians. Speech-in-noise and gap-detection thresholds were found to decline at a slower rate in musicians, providing an increasing advantage with age. Furthermore, musicians had a lifelong advantage in detecting a mistuned harmonic, although the rate of age-related decline was similar for both musicians and non-musicians. Importantly, there was no significant effect of musicianship on pure-tone thresholds, suggesting that lifelong musicianship can mitigate age-related decline in central but not peripheral auditory processing. To test this hypothesis, a second experiment compared auditory evoked responses (AERs) between groups of older and younger musicians and non-musicians. Results indicated that exogenous neural activity was enhanced in musicians, but that age-related changes were similar between musicians and nonmusicians. Furthermore, endogenous, attention-dependent neural activity was enhanced in older adults, suggesting a compensatory cognitive strategy. Importantly, endogenous activity was preferentially enhanced in older musicians, suggesting that lifelong musicianship enhanced cognitive processes related to auditory perception. In the final experiment, the ability to segregate simultaneous sounds was tested in older and younger musicians and non-musicians by using a mistuned harmonic paradigm, where AERs to harmonic complexes were compared to AERs when one of the harmonics was mistuned. Results indicated that musical training in older adults has little effect on early automatic registration of the mistuned harmonic. In contrast, late attention-dependent activity, associated with the perception of the mistuned harmonic as a separate sound, was influenced by musical training in older adults, suggesting that lifelong musicianship preserves or enhances cognitive components of concurrent sound segregation. In summary, musical training was found to reduce age-related decline in hearing abilities due to enhanced central processing of auditory information.

INTRODUCTION Autonomic control of cardiac function is fundamental for the maintenance of circulatory homeostasis under changing environmental and behavioral conditions (Pardini et al., 1987). The intrinsic cardiac nervous system is principal in the maintenance of the adequate cardiac output, the power, the rate of contraction, and the volume of blood delivered to cardiac muscle thorough the coronary vasculatures (Armour and Ardell, 1994). For many years it has been thought that cardiac ganglia possess only cholinergic parasympathetic postganglionic neurons and serve as simple stations of transmission of inhibitory impulse to the heart (Mawe et al., 1996). However, recent morphological and physiological evidence indicates that the mammalian intrinsic cardiac nervous system contains afferent sensory (Ardell et al., 1991; Armour and Hopkins, 1990; Cheng et al., 1997), efferent sympathetic and parasympathetic postganglionic neurons (Horackova et al., 1996; Mawe et al., 1996; Randall et al., 1987), and a population of local circuit neurons that function to interconnect neurons within and between the separate aggregates of ganglia that form the various intrinsic cardiac ganglionated plexuses (Butler et al., 1990). These neurons might be unipolar, bipolar or multipolar in shape (Armour et al., 1997; Baptista and Kirby, 1997; Edwards et al., 1995; Xi et al., 1991) and possesses varied immunohistochemical properties (Singh et al., 1999). Functionally diverse cardiac ganglion neurons... [to full text]

Gap dynamics theory proposes that forest canopy gaps provide the high light levels needed for regeneration. Little attention has been given to more gradual alternatives; however, recent studies have demonstrated declines in within-crown leaf area index with tree size in temperate forest trees. Our project builds on this previous research by assessing the prevalence of this age-related crown thinning phenomenon. We quantified crown openness for 18 dominant tree species in temperate and tropical forests (n = 1786 trees). Separate pooled groupings of tropical and temperate species showed significantly positive relationships between openness and DBH (p<0.001). Of the 9 sampled species showing positive relationships, significance (p< 0.05) was detected in 3 out of 10 tropical species and 1 out of 8 temperate species. Two temperate species showed significantly reduced canopy openness with size. These trends highlight the role that very large trees play in influencing light availability for understorey regeneration.

Gap dynamics theory proposes that forest canopy gaps provide the high light levels needed for regeneration. Little attention has been given to more gradual alternatives; however, recent studies have demonstrated declines in within-crown leaf area index with tree size in temperate forest trees. Our project builds on this previous research by assessing the prevalence of this age-related crown thinning phenomenon. We quantified crown openness for 18 dominant tree species in temperate and tropical forests (n = 1786 trees). Separate pooled groupings of tropical and temperate species showed significantly positive relationships between openness and DBH (p<0.001). Of the 9 sampled species showing positive relationships, significance (p< 0.05) was detected in 3 out of 10 tropical species and 1 out of 8 temperate species. Two temperate species showed significantly reduced canopy openness with size. These trends highlight the role that very large trees play in influencing light availability for understorey regeneration.