by Rebecca McGreal. / Vita. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web. / The central premise of this dissertation is that the small heat shock protein (sHSP), (Sa(BB-crystallin is essential for lens and retinal pigmented epithelial (RPE) cell function and oxidative stress defense. To date, the mechanism by which it confers protection is not known. We hypothesize that these functions could occur through its ability to protect mitochondrial function in lens and RPE cells. To test this hypothesis, we examined the expression of (Sa(BB-crystallin/sHSP in lens and RPE cells, we observed its localization in the cells, we examined translocation to the mitochondria in these cells upon oxidative stress treatment, we determined its ability to form complexes with and protect cytochrome c (cyt c) against damage, and we observed its ability to preserve mitochondrial function under oxidative stress conditions in lens and RPE cells. In addition to these studies, we examined the effect of mutations of (Sa(BB-crystallin/sHSP on its cellular localization and translocation patterns under oxidative stress, its in vivo and in vitro chaperone activity, and its ability to protect cyt c against oxidation. Our data demonstrated that (Sa(BB-crystallin/sHSP is expressed at high levels in the mitochondria of lens and RPE cells and specifically translocates to the mitochondria under oxidative stress conditions. We demonstrate that (Sa(BB-crystallin/sHSP complexes with cyt c and protects it against oxidative inactivation. Finally, we demonstrate that (Sa(BB-crystallin/sHSP directly protects mitochondria against oxidative inactivation in lens and RPE cells. Since oxidative stress is a key component of lens cataract formation and age-related macular degeneration (AMD), these data provide a new paradigm for understanding the etiology of these diseases.

The rodent hippocampus is critical for processing spatial memory but its contribution to non-spatial, specifically object memory is debated. The cognitive map theory of hippocampal function states that the hippocampus stores relationships of goal locations (places) to discrete items (objects) encountered within environments. Dorsal CA1 place cells were recorded in male C57BL/6J mice performing three variations of the novel object recognition paradigm to define "object-in-context" representation of hippocampal neuronal activity that may support object memory. Results indicate, (i) that place field stability is higher when polarizing environmental cues are provided during object recognition; (ii) hippocampal place fields remain stable throughout the novel object recognition testing without a polarizing cue; and (iii) time dependent effects on stability when objects were dissociated from the context. These data indirectly support that the rodent hippocampus processes object memory, and challenge the view that "object-in-context" representations are formed when mice perform novel object recognition task. / by Herborg Nanna âAsgeirsdâottir. / Thesis (M.A.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

The function and role of PAK6, serine/threonone kinase, in cancer progressionhas not yet been clearly identified. Several studies reveal that PAK6 may participate in key changes contributing to cancer progression such as cell survival, cell motility, and invasiveness. Basedon the membrane localization of PAK6 in prostate and breast cancer cells,we speculated that PAK6 plays a rolein cancer progression cells by localizing on the membrane and modifying proteins linked to motility and proliferation. We isolated the raft domain of breast cancer cells expressing either wild type (WT), constitutively active (SN), or kinase dead PAK6 (KM) and found that PAK6 is a membrane associated kinase which translocates from the plasma membrane to the cytosol when activated. The downstream effects of PAK6 are unknown ; however, results from cell proliferation assays suggest a growth regulatory mechanism. / by JoAnn Roberts. / Thesis (M.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

The classic guidance molecules, Netrin and its receptor Frazzled (Fra), dictate the strength of synaptic connections in the giant fiber system (GFS) of Drosophila melanogaster by regulating gap junction localization in the pre-synaptic terminal. In Netrin mutant animals the synaptic coupling between a giant interneuron and the jump motor neuron was weakened. Dye-coupling between these two neurons was severely compromised or absent. These mutants exhibited anatomically and physiologically defective synapses between the giant fiber (GF) and tergotrochanteral motor neuron (TTMn). In cases where Netrin mutants displayed apparently normal synaptic anatomy, half of the specimens exhibited physiologically defective synapses. Dye-coupling between the giant fiber and the motor neuron was reduced or eliminated, suggesting that gap junctions were disrupted in the Netrin mutants. When we examined the gap junctions with antibodies to Shaking-B Innexin (ShakB), they were significantly decreased or absent in the pre-synaptic terminal of the mutant GF. This data is the first to show that Netrin and Frazzled regulate placement of gap junctions pre-synaptically at a central synapse. In the Drosophila Giant Fiber System, we demonstrate a mechanism that ensures the monoinnervation of two homologous motor neurons by two homologous interneurons. In a scenario where both interneurons could synapse with both motor neuron targets, each interneuron exclusively synapsed with only one target and the circuit functions at normal physiological levels. This innervation pattern depended on the ratio of netrin-to-frazzled expression. When Netrin was over expressed in the system, shifting the ratio in favor of Netrin, both interneurons synapsed with both target motor neurons and physiological function was reduced. This resulted in the polyinnervationof a single target. In contrast, when Frazzled was over expressed in the system, one interneuron innervated both targets and excluded the remaining interneuron from making any synaptic contact. This resulted in a single interneuron mono-innervating both motor neurons and physiological function was mutant. The orphaned interneuron made no synaptic contact with either motor neuron target. Physiological function was only normal when the Netrin-Frazzled ratio was at endogenous levels and each GF monoinnervated one motor neuron. When we examined the gap junctions at this synapse in experimental animals, there was a significant reduction of gap junction hemichannels in the presynaptic terminal of axons that deviated from normal innervation patterns. While the synapse dyecoupled, the reduction in gap junction hemichannels reduced function in the circuit. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.

In the developing CNS, presynaptic neurons often have exuberant overgrowth and form excess (and overlapping) postsynaptic connections. Importantly, these excess connections are refined during circuit maturation so that only the appropriate connections remain. This synaptic rearrangement phenomenon has been studied extensively in vertebrates but many of those models involve complex neuronal circuits with multiple presynaptic inputs and postsynaptic outputs. Using a simple escape circuit in Drosophila melanogaster (the giant fiber circuit), we developed tools that enabled us to study the molecular development of this circuit; which consists of a bilaterally symmetrical pair of presynaptic interneurons and postsynaptic motorneurons. In the adult circuit, each presynaptic interneuron (giant fiber) forms a single connection with the ipsilateral, postsynaptic motorneuron (TTMn). Using new tools that we developed we labeled both giant fibers throughout their development and saw that these neurons overgrew their targets and formed overlapping connections. As the circuit matured, giant fibers pruned their terminals and refined their connectivity such that only a single postsynaptic connection remained with the ipsilateral target. Furthermore, if we ablated one of the two giant fibers during development in wildtype animals, the remaining giant fiber often retained excess connections with the contralateral target that persisted into adulthood. After demonstrating that the giant fiber circuit was suitable to study synaptic rearrangement, we investigated two proteins that might mediate this process. First, we were able to prevent giant fibers from refining their connectivity by knocking out highwire, a ubiquitin ligase that prevented pruning. Second, we investigated whether overexpressing Netrin (or Frazzled), part of a canonical axon guidance system, would affect the refinement of giant fiber connectivity. We found that overexpressing Netrin (or Frazzled) pre- & postsynaptically resulted in some giant fibers forming or retaining excess connections, while exclusively presynaptic (or postsynaptic) expression of either protein had no effect. We further showed that by simultaneously reducing (Slit-Robo) midline repulsion and elevating Netrin (or Frazzled) pre- & postsynaptically, we significantly enhanced the proportion of giant fibers that formed excess connections. Our findings suggest that Netrin-Frazzled and Slit-Robo signaling play a significant role in refining synaptic circuits and shaping giant fiber circuit connectivity. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Obesity is associated with elevated levels of the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), contributing to systemic insulin resistance. Fibroblast growth factor 21 (FGF21) is a vital metabolic and inflammatory regulator, however circulating FGF21 concentrations are elevated in obese individuals. Acute aerobic exercise increases systemic FGF21 in normal-weight individuals, however the effect of acute aerobic exercise on plasma FGF21 response and the relationships with inflammation (IL-6 and TNF-α), insulin resistance, and energy expenditure in obese individuals is unknown. Following 30 minutes of treadmill running at 75% VO2max, plasma FGF21 response, as indicated by area-under-the-curve “with respect to increase” (AUCi) analyses, was attenuated in 12 obese compared to 12 normalweight subjects. Additionally, FGF21 AUCi positively correlated with glucose AUCi, total relative energy expenditure, and relative VO2max, suggesting that cardiorespiratory fitness levels may predict FGF21 response, contributing to the enhanced regulation of glucose and energy metabolism. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Neurons are able to maintain membrane potential and synaptic integrity by an intricate equilibrium of membrane transporter proteins and ion channels. Two membrane proteins of particular importance in the vertebrate retina are the excitatory amino acid transporters (EAATs) which are responsible for the reuptake of glutamate into both glial and neuronal cells and the sodium potassium chloride cotransporters (NKCCs) that are responsible for the uptake of chloride ions into the cell. NKCCs are electro-neutral with the uptake of 2 Cl- coupled to an exchange of a potassium and Na+ ion into the cells. Therefore, there is little change of cell membrane potential in the action of NKCCs. In this study the localization and function of EAATs in the distal retina is investigated. Whole cell patch clamp recordings in lower vertebrate retina have demonstrated that EAAT2 is the main synaptic EAATs in rod photoreceptors and it is localized to the axon terminals. Furthermore, the action of the transporter seems to be modified by intracellular calcium concentration. There is also evidence that EAAT2 might be regulated by feedback from the neuron network by glycinergic and GABAergic mechanisms. The second half of this study investigates expression of NKCCs in the retina by western blot analysis and quantitative polymerase chain reaction. There are two forms of NKCCs, NKCC1 and NKCC2. NKCC1 is mostly expressed in the central nervous system and NKCC2 was thought to only be expressed in the kidneys. NKCC1 is responsible for the majority of chloride uptake into neuronal and epithelial cells and NKCC1 is expressed in the distal retina where photoreceptors synapse on second order horizontal and bipolar cells. This study found the expression of NKCC1 in the distal retina to be regulated by temporal light and dark adaptation. Light adaptation increased phosphorylated NKCC1 expression (the active form of the cotransporter). The increase in NKCC1 expression during light adaptation was modulated by dopamine. Specifically, a D1 receptor agonist increased phosphorylated NKCC1 expression. Dopamine is an essential chemical and receptor known for initiating light adaptation in retina. Finally, an NKCC1 knockout mouse model was examined and it revealed that both forms of NKCC are expressed in the vertebrate retina. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Small conductance Ca2+-activated K+ (SK) channels have been shown to alter the encoding of spatial and non-spatial memory in the hippocampus by shaping glutamatergic postsynaptic potentials and modulating NMDA receptor-dependent synaptic plasticity. When activated, dendritic SK channels reduce hippocampal neuronal excitability and LTP. Similar SK channel properties have been demonstrated in lateral amygdala (LA) pyramidal neurons. Additionally, induction of synaptic plasticity and beta-adrenoreceptor activation in LA pyramidal neurons causes PKA-mediated internalization of SK channels from the postsynaptic density. Chronic activation of the amygdala through repetitive stressful stimuli can lead to excitatory synaptic strengthening that may create permanent hyper-excitability in its circuitry. This mechanism may contribute to a number of mood and anxiety disorders. The selective influence of SK channels in the LA on anxiety and fear conditioning are not known. The thesis project outlined herein examined whether SK channel blockade by bee venom peptide, apamin, during a repetitive acute fear conditioning paradigm was sufficient to alter fear memory encoding and the resulting behavioral outcome. Following the final fear memory test session, mice were tested in the open field immediately after the second fear conditioning test session. The findings indicate that intracranial LA microinfusions of apamin did not affect memory encoding or subsequent anxiety. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

The purpose of this study was to examine the acute and temporal response of CK- MM and FGF-21 to 3-day/wk. different repetition-range, volume-equated resistance training programs over 8-weeks in previously trained males. Sixteen trained, college- aged males were counterbalanced into high (DUP-HR) or low (DUP-LR) repetition groups. Subjects performed the squat and bench press 3x/wk. for 8 weeks. Blood samples were collected at various intervals throughout the study. Trained individuals did not elicit significant acute or chronic changes in CK-MM or FGF-21 following training and the lack of change was present in both groups. Additionally, neither biomarker correlated with changes in 1RM strength. There was a very strong correlation between acute mean (r=0.95) and acute percentage change (r=0.97) increase from pre training to post training in week #1. Additionally, a moderate correlation in percentage change was observed (r=0.59) of both biomarkers from pre training to 48 hours post training in week #2. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection

All of the above findings demonstrated that eosinophil activation in allergic inflammation could be sensitively regulated by diverse stimuli. Besides, highly redundant functional effects and underlying signaling mechanisms were observed among different mediators. Elucidation of the mechanisms of eosinophil activation could improve our understanding of its complex and active role in the pathogenesis of allergic diseases, thereby providing biochemical basis for the development of more effective therapeutic strategies for treating the diseases. (Abstract shortened by UMI.) / Apart from the cytokines produced by T lymphoctyes, leptin, a cytokine produced by adipocytes, was also demonstrated to activate eosinophils. It was reported that the plasma levels of leptin were elevated in both obese and allergic patients. We found that leptin could activate eosinophils for survival enhancement, adhesion and migration, and secretion of cytokines and chemokines. Besides, we showed that the MAPKs and NF-kappaB pathways were involved in eosinophil adhesion, migration and mediator release induced by leptin, while Janus kinases (JAK)-signal transducers and activators of transcription (STAT) pathway was responsible for leptin-induced eosinophil survival. Our study indicated a potential correlation between obesity and exacerbation of allergic inflammation. / Eosinophilia is a hallmark pathological feature of allergic diseases and it has been targeted as a novel therapeutic strategy for allergic diseases. / In atopic dermatitis (AD), dermal infiltration of eosinophils is one of the pathological features of this disease. IL-31 is a novel Th2 cytokine reported to induce pruritus and skin dermatitis resembling human AD. Our study on the co-culture system of eosinophils and keratinocyte cell line HaCaT illustrated the production of pro-inflammatory cytokines and chemokines from the co-culture system of eosinophils and HaCaT cells, under the stimulation of IL-31. In co-culture system, surface expression of CD18 and intercellular adhesion molecule (ICAM)-1 on eosinophils and HaCaT cells was also up-regulated respectively, implying a direct interaction between the two cell types through their cell surface adhesion molecules. The interaction of eosinophils and HaCaT cells under IL-31 stimulation was shown to be mediated through MAPKs, NF-kappaB and PI3K pathways. These findings therefore elucidate the immunological roles of IL-31, eosinophils and keratinocytes in AD. / In the present study, we investigated the mechanisms of eosinophil activation induced by various stimuli including novel T helper type 2 (Th2) cytokines, adipokine, microbial products and direct interaction with tissue cells. The activation of eosinophils was studied in terms of survival enhancement, modulation of adhesion and migration, and the release of inflammatory mediators including cytokines, chemokines, granular proteins and superoxide. Using pharmacological and molecular approaches, we further investigated the intracellular signaling mechanisms regulating the eosinophil activation mediated by various stimuli. / Increasing evidence has indicated that bacterial and viral infections could intensify allergic responses. Our findings demonstrated that eosinophil activation could be elicited by microbes through toll-like receptors (TLRs), the recently discovered receptors for the recognition of conserved motifs in pathogens. We found that eosinophils could be activated by the ligands of TLR2, 5 and 7 in enhancing survival, adhesion and migration, release of pro-inflammatory cytokines, chemokines, granular proteins and superoxides. These stimulatory effects, mediated by TLR2, 5 and 7, were differentially regulated by MAPKs, NF-kappaB and phosphatidylinositol 3-kinase (PI3K) pathways. Moreover, an important finding of our study is the common involvement of focal adhesion kinase (FAK)-dependent extracellular-regulated protein kinase (ERK) phosphorylation in the signaling of TLR 2, 5 and 7, implying a special role of FAK in linking TLR signaling with MAPKs cascade in human eosinophils. Our study on microbe-induced eosinophil activation provided a potential explanation for linking infection with exacerbation of allergic diseases. / The interleukin (IL)-17 family is a newly discovered group of cytokines which was reported to be important in allergic inflammation. We studied the roles of two IL-17 family members, IL-175E/IL-25 and IL-17F on eosinophil activation. Both cytokines were found to induce the secretion of inflammatory cytokines and chemokines from eosinophils, in which IL-25 could also enhance eosinophil survival and adhesion. Besides, we found that the stimulatory effects induced by both IL-25 and IL-17F were mediated through mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappaB) pathways. The main source of IL-17F has recently been reported to be a novel T lymphocyte population, Th17, which is specifically driven by IL-23. An important finding of our present study was the synergistic effects of IL-17F and its potent inducer, IL-23, on cytokine release from eosinophils. Since IL-23 was produced by macrophages and dendritic cells upon microbial stimulation, the synergistic effect of IL-17F and IL-23 on eosinophil activation might imply a potential role in linking microbial infection and allergic inflammation. Our findings also provide further support to the crucial role of the IL-17 family and Th17 lymphocytes in the amplification of allergic diseases. / Cheung, Fung Yi. / Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1552. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 205-221). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.