VictorJuiz/thesis huggingface dataset:
Pencil Grasp Pattern: How Critical is it to Functional Handwriting?

This thesis reports the results of a large study to evaluate the kinetics of pencil grasp patterns in terms of speed and legibility of handwriting of children in Grade 4. Current clinical practice as recent as 2008 suggests that teachers identify the dynamic tripod pencil grasp as an optimal pencil grasp for handwriting. Research findings had suggested that three other pencil grasps may be functional for handwriting, though there was still inconclusive evidence upon which to base clinical practice. The purpose of the present study was to: assess the impact of pencil grasp on the speed and legibility of handwriting; to determine the effect of grasp on speed and legibility following a 10-minute copy task intended to induce fatigue; and to describe the axial and grip forces of the four pencil grasps. 120 children were assessed, completing a standardized handwriting assessment before and after a 10-minute copy task. The participants utilized an instrumented pen and wrote on a digitizing tablet, which measured, respectively, the axial and grip forces associated with their grasp patterns. Pencil grasp was not found to impact the speed or legibility of the written product in either short or long duration copy tasks. Fatigue decreased the legibility of the product across all pencil grasps but increased the speed across all pencil grasps equally. Grip and axial forces were only different in grasps with an adducted thumb and mainly during the initial assessment. Collectively, these results suggest that four mature grasps are equally functional for handwriting in children of this age. These findings contradict common clinical impressions that the dynamic tripod pencil grasp is optimal.

Keywords: children
handwriting
Advisor: Chau, Tom
Carnahan, Heather
Regulation of Adult Neurogenesis: Factors Affecting the Production and Development of New Neurons

In the mature dentate gyrus (DG) new neurons are continuously produced in a process known as adult neurogenesis. These neurons are thought to contribute to learning and memory processes, but their precise function is still not fully understood. The rate of neuronal production and the development of young neurons are affected by stimuli such as physical exercise and learning events. The neurotransmitter γ-aminobutyric acid (GABA) has recently emerged as a possible key mediator of this activity-dependent regulation. My study examined the role of a subtype of GABAA receptors that contains the δ subunit (δGABA(A)R) in the regulation of adult hippocampal neurogenesis. Mice lacking the δ subunit (Gabrd−/− or δ-null mice) displayed decreased maturation, migration and dendritic complexity of adult-born neurons. Conversely, following treatment with a selective δGABA(A)R agonist, neuronal maturation was promoted in wild-type, but not δ-null mice. These results indicate a key role for δGABA(A)R in activity-dependent regulation of adult neurogenesis. When administered to rats, δGABA(A)R agonists promoted neuronal survival as well as maturation. The effect on maturation was blocked by the N-Methyl-D-aspartate (NMDA) blocker AP-5, suggesting that some aspects of δGABA(A)R-mediated regulation require the activation of NMDA receptors. To further understand the contribution of adult born neurons to memory function, neurogenesis in rats was alternatively suppressed using ionizing radiation, or enhanced by allowing the rats to engage in running. The rats were then trained and tested in a behavioral paradigm designed to assess their susceptibility to memory interference, a phenomenon which occurs when similar memories are not sufficiently distinguished from one another. Irradiated rats exhibited increased susceptibility to memory interference, indicating an important role for adult-born neurons in the encoding and/or retrieval of distinct memories. Remarkably, irradiated rats that engaged in running exhibited increased neuronal growth and a complete reversal of the memory impairment,emphasizing the beneficial effects of physical exercise on cognitive functions. Taken together, the findings reported in this dissertation offer novel information about the process of adult neurogenesis and its physiological significance.

Keywords: adult neurogenesis
GABA
Advisor: Wojtowicz, Jan Martin
Mobilization of Procollagen and Lysosomes during Osteoblast Stimulation with Ascorbic Acid

Despite advances in investigating functional aspects of osteoblast (OB) differentiation, especially studies on how bone proteins are deposited and mineralized, there has been little research on the intracellular trafficking of bone proteins during OB differentiation. Collagen synthesis and secretion is the major function of OBs and is markedly upregulated upon ascorbic acid (AA) stimulation, significantly more so than in fibroblast cells. Understanding the mechanism by which collagen is mobilized in specialized OB cells is important for both basic cell biology and bone disease studies. Cellular organelles and vesicles in the exocytic and endocytic pathways have a distinctive spatial distribution and their trafficking is aided by many molecules, Rab GTPases being a master regulator. In this work, I identified the Rab GTPases that are upregulated during OB differentiation using microarray analysis, namely Rab1, Rab3d, and Rab27b, and investigated their role in regulating the trafficking of collagen from the site of synthesis in the ER to the Golgi and ultimately to the plasma membrane (PM) utilizing their dominant negative (DN) expression. The experimental halting of biosynthetic trafficking by these mutant Rabs initiated proteasome-mediated degradation of procollagen and ceased global protein translation. Acute expression of Rab1 and Rab3d DN constructs resulted in impaired ER to Golgi trafficking of procollagen. Similar expression of Rab27b DN constructs resulted in dispersed collagen vesicles which may represent failed secretory vesicles sequestered in the cytosol. A significant and strong reduction in extracellular collagen levels also was observed showing roles of Rab1, Rab3d and Rab27b in the specific function of these major collagen producing cells in the body. I further observed that a fraction of procollagen colocalized with lysosomes which was markedly increased when procollagen was experimentally misfolded. Lysosomes, essential organelles for intracellular degradation, are generally sequestered near the cell centre to receive vesicles with contents targeted for destruction. During AA-induced differentiation of OB cells, I saw a marked increase in total degradative lysosome organelles in addition to an enhanced endocytic rate. Interestingly, lysosomes were dispersed toward the cell periphery in differentiating OBs without being secreted. This required intact microtubules for long range transport and was kinesin motor-dependent but did not involve cytosolic acidification. Moreover, impairment of lysosome dispersion markedly reduced AA-induced OB differentiation. Taken together, this study provides an important general mechanism for cell secretion phenomena that may ultimately lead to clinical targets for treatments of diseases driven by aberrant collagen processing and secretion including Osteogenesis Imperfecta (OI).

Keywords: Bone cells
collagen
Advisor: Harrison, Rene E.
Role of the Rho GEF, Lfc, in Macrophage and Neutrophil Function

Lfc is a Rho specific guanine nucleotide exchange factor (GEF) that is bound and inhibited by the microtubule (MT) cytoskeleton. In epithelial cells, Lfc promotes actomyosin contractility in response to MT depolymerization; however, its role in leukocytes has not been assessed. Through genetic ablation, we generated an Lfc knockout mouse (Lfc-/-) and tested biochemical and cell biological responses to MT depolymerization in bone marrow derived cells. Lfc was necessary for characteristic actomyosin based contractile behaviours of neutrophils and macrophages, in response to MT depolymerization. Gout is a painful arthritic inflammatory disease, caused by buildup of monosodium urate (MSU) crystals in the joints. Colchicine, a MT-depolymerizing agent that is used in prophylaxis and treatment of acute gout flare, blocks neutrophil infiltration to sites of MSU crystal-induced inflammation. We found that Lfc was necessary for the ability of colchicine to inhibit MSU-induced neutrophil infiltration in two in vivo models of gout-like inflammation. Efficient recruitment of leukocytes from the vasculature is a critical step in the immune response to infection. Leukocyte extravasation, which includes rolling, crawling, and diapedesis across the endothelial barrier, is enhanced by fluid shear stress. Through comparison of Lfc+/+ and Lfc-/- mice, we found that Lfc was necessary for in vivo leukocyte crawling and emigration out of the vasculature. Lfc-/- mice also showed defective neutrophil infiltration in response to acute inflammatory insults, and increased mortality in response to polymicrobial infection. In vitro, we found that Lfc was necessary for neutrophil responses to shear stress.

Keywords: immunology
neutrophil
macrophage
gout
septic shock
Advisor: Rottapel, Robert
Carn Mor de Chlachan Beaga, A Large Cairn from Small Stones: Multivocality and Memory in Cape Breton Gaelic Singing

Since the first Scottish Gaelic-speaking settlers arrived in Nova Scotia in the late 18th century, their Gaelic singing tradition has been an integral part of life in communities on Cape Breton Island. With the waning of the Gaelic language, however, came efforts to collect and preserve the song tradition, and the intention to pass it along intact. This dissertation eschews the consideration of Gaelic singing as a monolithic tradition with a common repertoire and experience, and instead examines it as a multifaceted process enacted by individuals in three main sites: home, public performance and the archive. It examines the various ways the practice manifests itself, concluding that memory and individual agency are constants, both for singers and listeners. Through interviews, participant-observer activity and archival research, this study demonstrates that Gaelic singers have been far from passive culture-bearers but have instead actively shaped their song practice by choosing repertoire, melody variants and texts. It also discusses the dynamic role of memory and social interaction in the transmission and performance of Gaelic song. Memories of other singers, discussion of the text, and contextual details draw singers and listeners into a community that is both synchronic and diachronic. This practice is chiefly oral, but is supported by recordings and printed songbooks as well as an array of objects – photo albums, clippings, tapes – which evoke the sense of previous performances and their singers. Despite their intention to transmit the songs with little or no change, singers have a flexible relationship with the material and in some cases subvert the authority of recorded or printed sources by turning instead to first-hand experiences. This simultaneous presence of past and present has tremendous implications for what it means to know a song, and one comes to understand it as a composite of multiple memories, performances and meanings.

Keywords: Gaelic
Cape Breton
song
singing
tradition
musical transmission
memory
phenomenology
Scotland
Nova Scotia
ethnomusicology
folklore
archive
music and place
Turner
Ricoeur
Advisor: Kippen, James R.
Cognitive Rhythm Generators for Modelling and Modulation of Neuronal Electrical Activity

An innovative mathematical architecture for modelling neuronal electrical activity is presented, called the cognitive rhythm generator (CRG), wherein the proposed architecture is a hybrid model comprised of three interconnected stages, namely: (1) a bank of neuronal modes; (2) a ring device (limit-cycle oscillator); and (3) a static output nonlinearity (mapper). Coupled CRG networks are employed to emulate and elucidate the dynamics of biological neural networks, including the recurrent networks in the hippocampus. Several species of ring devices are described and investigated, including the clock, labile clock, hourglass and multistable ring systems, and their applications to neuronal modelling explored. Complexity measures such as the maximum Lyapunov exponent, correlation dimension and detrended fluctuation analysis are applied to compare model and biological records and validate the CRG methodology. The basis of neural coding is also examined in mathematical detail, with particular regard to its description by Volterra-Wiener kernel formalism, from which the neuronal modes are derived. Applications to theta-gamma coding are discussed. Further on in the thesis, a CRG epileptiform network model of spontaneous seizure-like events (SLEs) is developed and used as a platform to test neuromodulation approaches for seizure abatement. (Neuromodulation mentioned here refers to methods involving electrical stimulation of neural tissue for therapeutic benefit). Spontaneous SLE transitions in the epileptiform network are shown to be related to the mechanism of intermittency, as determined by examining the state space dynamics of the model. The onset of SLEs is associated with increased network excitability and decreased stability, consistent with experimental results from the low-magnesium/high-potassium in vitro model of epilepsy. Lastly, a novel strategy for therapeutic neuromodulation is presented wherein a coupled CRG network (called the “therapeutic network”) is interfaced with the epileptiform network model, forming a closed loop for responsive, biomimetic neuromodulation of the epileptiform network. Relevance to clinical applications and future work is discussed.

Keywords: Closed Loop
Cognitive Device
Complexity
Computer Model
Coupled Oscillators
Epilepsy
Neuromodulation
Nonlinear Dynamics
Neuronal Network
Seizure-Like Event
Seizure Transition
Therapeutic
Advisor: Bardakjian, Berj
The Role of PTEN in Pancreatic Beta Cells and Insulin Promoter-expressing Neurons in Modulating Glucose Metabolism and Energy Homeostasis

PI3K signaling in pancreatic β cells has been shown to be important in modulating β cell mass and function under basal condition. Evidence suggests that a specific group of insulin promoter-expressing neurons also modulates glucose metabolism and energy homeostasis through their PI3K signaling. Thus we hypothesize that PI3K activation via PTEN deletion under the control of rat insulin promoter (RIP) in pancreatic β cells and RIP-expressing neurons will protect against hyperglycemia and diabetes in experimentally induced mouse models of type 2 diabetes. In Chapter IV, we showed that RIP-mediated PTEN deletion in pancreatic β cells led to PI3K activation and subsequent increased β cell mass and function, thus protected the mice from high fat diet (HFD)-induced diabetes. Furthermore in the absence of global leptin signaling, β cell-specific PTEN deletion maintained β cell function in the setting of severe insulin resistance, therefore prevented diabetes development. Interestingly, RIP-mediated PTEN deletion also resulted in increased peripheral insulin sensitivity due to PI3K activation in central nervous system. In Chapter V, we showed this increased insulin sensitivity was maintained after HFD feeding, which also contributed to the protection against diabetes. These mice also showed increased visceral adipogenesis and subcutaneous adiposity on HFD, which were dramatically attenuated in the absence of leptin signaling, indicated the essential role of peripheral leptin action in mediating the insulin sensitive phenotype from neuronal RIP PTEN deletion. Finally, we demonstrated that the insulin sensitizing phenotype in these mice was not mediated through ventromedial hypothalamic nuclei (VMH), such that VMH-specific PTEN deletion did not alter energy homeostasis or glucose metabolism. Together, the data from this thesis points to an inhibitory role of PTEN in both central nervous system and pancreatic β cells in glycemic control. Therefore, PTEN may represent a potential target for diabetes prevention and treatment.

Keywords: type 2 diabetes
neuronal
PTEN
rat insulin promoter
insulin sensitivity
pancreatic beta cell mass and function
Advisor: Woo, Minna
Control Strategies for the Next Generation Microgrids

In the context of the envisioned electric power delivery system of the future, the smart grid, this dissertation focuses on control and management strategies for integration of distributed energy resources in the power system. This work conceptualizes a hierarchical framework for the control of microgrids---the building blocks of the smart grid---and develops the notion of potential functions for the secondary control for devising intermediate set points to ensure feasibility of operation of the system. A scalar potential function is defined for each controllable unit of the microgrid such that its minimization corresponds to achieving the control goal. The set points are dynamically updated using communication within the microgrid. This strategy is generalized to (i) include both local and system-wide constraints and (ii) allow a distributed implementation. This dissertation also proposes and evaluates a simple yet elaborate distributed strategy to mitigate the transients of controllable devices of the microgrid using local measurements. This strategy is based on response monitoring and is augmented to the existing controller of a power system device. This strategy can be implemented based on either set point automatic adjustment (SPAA) or set point automatic adjustment with correction enabled (SPAACE) methods. SPAA takes advantage of an approximate model of the system to calculate intermediate set points such that the response to each one is acceptable. SPAACE treats the device as a generic system and monitors its response and modulates its set point to achieve the desired trajectory. SPAACE bases its decisions on the trend of variations of the response and accounts for inaccuracies and unmodeled dynamics. Case studies using the PSCAD/EMTDC software environment and MATLAB programming environment are presented to demonstrate the application and effectiveness of the proposed strategies in different scenarios.

Keywords: Power system
Microgrid
Control
Distributed generation
Distributed control
Trajectory shaping
Smart grid
Distributed energy resrouce
Advisor: Reza, Iravani
Functional Analysis of the Pseudoprotease iRhom2 and Nonsense-mediated mRNA Decay Factor Smg1 using Gene Deficient Mice

This work involves the characterization of two genes using mouse models of gene deficiency and thus has two focuses: Focus I: Innate immune responses are vital for pathogen defence but can result in septic shock when excessive. A key mediator of septic shock is TNFα, which is shed into intercellular spaces after cleavage from the plasma membrane by the protease TACE. Here we report that the rhomboid family member iRhom2 interacts with TACE and regulates TNFα shedding in vitro and in vivo. Compared to controls, gene-targeted iRhom2-deficient mice showed reduced serum TNFα after LPS challenge survived a lethal LPS dose. Furthermore, iRhom2-deficient mice failed to adequately control the replication of Listeria monocytogenes and thus succumbed to even mild infections. Our study has identified iRhom2 as a novel regulator of innate immunity that may be an important target for modulating sepsis and pathogen defence. Focus II: Smg1 is a phosphatidylinositol 3-kinase-related kinase (PIKK) associated with multiple cellular functions, including DNA damage responses, telomere maintenance, and nonsense-mediated mRNA decay (NMD). NMD degrades transcripts that harbour premature termination codons (PTCs) due to events such as mutation or alternative splicing (AS). Recognition of PTCs during NMD requires the action of the Upstream frameshift protein Upf1, which must first be phosphorylated by Smg1. However, the physiological function of mammalian Smg1 is not known. Using a gene-trap model of Smg1 deficiency, we show that this kinase is essential for mouse embryogenesis such that Smg1 loss is lethal at embryonic day 8.5 (E8.5). High-throughput RNA sequencing (RNA-Seq) of RNA from cells of Smg1-deficient embryos revealed that Smg1 depletion led to pronounced accumulation of PTC-containing splice variant transcripts from ~9% of genes predicted to contain AS events capable of eliciting NMD. Among these genes are those involved in splicing itself, as well as genes not previously known to be subject to AS-coupled NMD, including several involved in transcription, intracellular signalling, membrane dynamics, cell death and metabolism. Our results demonstrate a critical role for Smg1 in early mouse development and link the loss of this NMD factor to major and widespread changes in the mammalian transcriptome.

Keywords: iRhom2
Smg1
TNF
nonsense mediated RNA decay
Advisor: Mak, Tak Wah
Toward the Development of Nucleic Acid Assays Using Fluorescence Resonance Energy Transfer (FRET) and a Novel Label Free Molecular Switching Construct

The research presented in this thesis introduces design criteria for development of a new type of self-contained optical biosensor. The study begins with evaluation of a dual label, fluorescence resonance energy transfer (FRET) bioassay format, and then goes on to demonstrate a signalling platform that uses an immobilized fluorescent intercalating dye so as to avoid labelling of both the target and probe strands. An extensive survey of FRET pairs that can be used to monitor hybridization events in solution and at solid interfaces was conducted in solution to provide a set of calculated Förster distances for the extrinsic labels Cyanine 3 (Cy3), Cyanine 5 (Cy5), Carboxytetramethylrhodamine (TAMRA), Iowa Black Fluorescence Quencher (IabFQ) and Iowa Black RQ (IabRQ). FRET parameters using thiazole orange (TO) intercalating dye as a FRET donor for various acceptor dye-labelled DNA conjugates in solution were determined. Limitations associated with quenching mechanisms other than those mediated by FRET motivated the development of a molecular switch that contained intercalating dye. The four binding sites associated with Neutravidin served for assembly of the switch using biotin interactions. One binding site was used to immobilize an unlabelled oligonucleotide probe. The adjacent site was used to immobilize a novel biotinylated TO derivative that could physically reach the probe. On hybridization of the probe with target, the intercalating dye was captured by the hybrid, leading to a change of fluorescence. This reversible signalling mechanism offers a method without nucleic acid labelling to detect nucleic acid association at an interface. A SNP discrimination strategy involving TO and formamide was investigated, and SNP discrimination without the requirement of thermal denaturation was achieved for multiple target lengths, including a 141-base pair PCR amplicon in solution. It was determined that formamide could also provide improvements of signal-to-noise when using thiazole orange to detect hybridization.

Keywords: fluorescence
molecular switch
nucleic acid
thiazole orange
Advisor: Krull, Ulrich Jorg