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<p> Polyurea microcapsules are micron-scale, hollow polymer spheres commonly used in agriculture to encapsulate pesticides for controlled diffusive release onto target crops. Diffusion of these active materials through a protective polymer wall offers a safer and more effective method of delivery compared to the direct spraying of crops with toxicants. The approach we are taking to control the release rate is to coat pre-formed porous polyurea capsules with a separate release-controlling outer layer. This allows us to separately optimize the load-bearing capsule wall and the release control layer, an approach commonly used in other membrane diffusion systems.</p> <p> Montmorillonite clay incorporation into polymer matrices can reduce membrane permeability by forcing diffusants to take a tortuous path around the stacked silicate sheets. Effective formation of clay-polyurea composites requires the delamination of clay particles into thin sheets with high aspect ratios, and their incorporation into polyurea microcapsules either during interfacial polymerization, or post-polymerization. The net negative surface charge of the silicate sheets should facilitate their initial binding to the cationic polyurea surfaces, as well as subsequent binding of polycations to the clay-coated polyurea capsules to create layer-by-layer (LbL) capsule assemblies with decreasing release rates of internal materials.</p> <p> The main focus of this project is to gain a fundamental understanding of montmorillonite clay and polyurea microcapsules, and the development of a model polyurea composite capsule for release rate analysis. Emphasis will be placed on the reduced permeability of microcapsules coated with clay by LbL assembly post-polymerization, followed by an exploration of further layering with polycations.</p> / Thesis / Master of Science (MSc)

<p>This study examined the effects of self-controlled and performance-based feedback schedules on the acquisition and retention of a novel motor task. In Experiment 1 participants performed an interception task on a computer using a mouse-controlled cursor. The goal of the task was to intercept the image of a red circle as it passed through a designated area. Each trial received a score based on the speed and accuracy of the interception movement. Participants were randomly assigned to three feedback groups: Best-trial feedback, Worst-trial feedback, and Self-controlled feedback. No differences were found between groups in acquisition, however analysis of no-feedback retention and transfer tests indicated that the Worst-trial group showed the most significant improvements in performance. Experiment 2 examined the potential mechanisms contributing to the advantages of a worst-trial feedback schedule. Participants in the second experiment performed the same interception task utilized in Experiment 1 under two novel feedback conditions: Estimation feedback and Immediate feedback. These new groups were compared to the Worst-trial group from Experiment 1. Analysis of no-feedback retention and transfer tests again indicated that the Worst-trial group showed the most significant improvements in performance. These results suggest that self-controlled schedules may not be ideal when feedback is based on performance; instead, specific error information for the least successful trials appear to be most beneficial, especially when individuals have knowledge of results regarding previous attempts at the task.</p> / Thesis / Master of Science (MSc)

Study design of a randomized-controlled trial investigating the effects of probiotic supplementation on induction of prediabetes remission to normoglycemia in adults with prediabetes. / BACKGROUND: Patients with prediabetes are at a high risk of developing type 2 diabetes (T2D) and the current strategies to prevent the progression of prediabetes to T2D are difficult to implement at the population level. Recently, the role of gut microbiota has emerged as a possible link to metabolic disease. The modulation of the gut microbiota in individuals with prediabetes through probiotic supplementation may improve metabolic dysfunction and induce remission of prediabetes to normoglycemia. OBJECTIVES: The primary objective of this trial is to determine the effect of 900 billion CFU/day of VSL#3®, a multi-strain probiotic supplement for 20 weeks, on induction of drug-free remission to normoglycemia (HbA1c<6.0%) in adults with prediabetes compared to placebo 20 weeks post-randomization. METHODS: In a randomized, triple-blind, controlled multi-centre trial, 568 adults with prediabetes will undergo a 2-week run-in after which they will be randomly allocated to 20 weeks of either 900 billion CFUs of VSL#3® per day or placebo. Prediabetes remission will be measured using HbA1C at week 20 and 32. Change in insulin resistance (HOMA-IR), beta-cell function (HOMA-B), weight, BMI, waist circumference and fecal relative abundance of bacteria will be measured from baseline at week 20 and 32. Exploratory regression analyses will involve a multiple logistic regression model to assess whether the change in relative abundance of the Rosburia genus from baseline at week 20 is an independent predictor of drug-free prediabetes remission at week 20. DISCUSSION: Individuals with prediabetes are at high risk of developing T2D and the induction of prediabetes remission would be important to patients and clinicians. The role of microbiota in metabolic processes presents the potential for therapeutic applications of probiotics. If successful, probiotics would offer a therapeutic option for reversing prediabetes to normoglycemia that is simple, cheap and easy to incorporate into standard clinical care. / Thesis / Master of Science (MSc) / BACKGROUND: Patients with prediabetes are at a high risk of developing type 2 diabetes (T2D) and the current strategies to prevent the progression of prediabetes to T2D are difficult to apply at the population level. Recently, the role of gut bacteria has emerged as a possible link to metabolic disease. Changing the gut microbiota in people with prediabetes through probiotic supplements may improve metabolic function and result in remission of prediabetes to normal glucose control. OBJECTIVES: The primary objective of this study is to determine the effect of VSL#3®, a probiotic supplement, for 20 weeks, on induction of drug-free remission to normal glucose control in adults with prediabetes compared to placebo, 20 weeks after randomization. METHODS: In a randomized, triple-blind, controlled multi-centre trial, 568 adults with prediabetes will be randomly assigned to 20 weeks of either VSL#3® per day or placebo. Prediabetes remission will be measured using HbA1C at week 20 and 32. Change in insulin resistance (HOMA-IR), beta-cell function (HOMA-B), weight, BMI, waist circumference and fecal bacteria will be measured from baseline at week 20 and 32. DISCUSSION: Individuals with prediabetes are at high risk of developing T2D and the induction of prediabetes remission would be important to patients and clinicians. The role of gut bacteria in metabolic health presents the potential for probiotics to be therapy options. If successful, probiotics would be simple, cheap and easy to incorporate into standard clinical care.

Molecular recognition is an important tool for developing tunable controlled release systems and fabricating biosensors with increased selectivity and sensitivity. The development of polymer-based materials that exploit molecular recognition events such as host-guest complexation, enzyme-substrate and enzyme-inhibitor interactions and nucleic acid hybridization was pursued in this thesis. Using polymers as an anchor for molecular recognition can enhance the affinity, selectivity, and the capacity for immobilization of recognition units, enabling the practical use of affinity-based systems in real applications. To introduce the potential for immobilization while preserving or enhancing the affinity of small molecule recognition units, the affinity of derivatized cyclodextrins for the hydrophobic drug, dexamethasone, was investigated. Cyclodextrins (CDs) are molecules that possess a hydrophilic exterior and a hydrophobic cavity capable of accommodating a wide range of small molecule guests. Analysis of the solubilization capacities, thermodynamic parameters and aggregative potentials of carboxymethyl and hydrazide derivatives of CDs established the dextran-conjugated βCD derivative as an ideal carrier of hydrophobic drugs and the hydrazide βCD derivative as an optimal solubilizer of lipophilic pharmaceuticals, both alone and when incorporated in a polymer-based drug delivery vehicle. To enable non-covalent immobilization and stabilization of biomacromolecular recognition units, a printed layer hydrogel was investigated as a selective diffusion barrier for analyte sensing and enzyme inhibitor recognition. A printable hydrogel platform was developed from an established injectable system composed of aldehyde- and hydrazide-functionalized poly(oligoethylene glycol methacrylate) polymers. The printed layer hydrogel effectively immobilized a wide range of enzymes and protected enzyme activity against time-dependent and protease-induced denaturation, while facilitating the diffusion of small molecules. Furthermore, to demonstrate the potential of the printed film hydrogel immobilization layer to enhance the selectivity of the target, the printable hydrogel platform was used to develop a microarray-based assay for the screening of inhibitors of the model enzyme, β-lactamase. The assay was able to accurately quantify dose-response relationships of a series of established inhibitors, while reducing the required reagent volumes in traditional drug screening campaigns by 95%. Most significantly, the assay demonstrated an ability to discriminate true inhibitors of β-lactamase from a class of non-specific inhibitors called promiscuous aggregating inhibitors. Finally, to enable non-covalent immobilization of DNA recognition units, the printable hydrogel-based microarray was tested for its ability to immobilize DNA recognition sites and promote the detection of DNA hybridization events. A long, concatameric DNA molecule was generated through rolling circle amplification and was used as a sensing material for the detection of a small, fluorophore labeled oligonucleotide. The printable hydrogel was able to effectively entrap the rolling circle amplification product. Properties of the printable hydrogel were investigated for their ability to support the detection of DNA hybridization events. / Thesis / Doctor of Philosophy (PhD) / This thesis describes the development of polymer-based materials that exploit molecular recognition events for drug delivery and biosensing applications. First, cyclodextrins (CDs) are molecules that are capable of binding a wide range of small molecules. A comprehensive analysis of the complexation properties of CD derivatives revealed critical insight regarding their application in polymer-based drug delivery vehicles. Second, a printable hydrogel platform was developed to support the immobilization and activity of biomolecules and establish a biosensing interface that facilitates the diffusion of small molecules but not molecular aggregates. A microarray-based assay was developed by employing the printed hydrogel interface for the screening of inhibitors of the model enzyme, β-lactamase, and the detection of DNA hybridization events.

The analgesic effect of 600 mg and 1500 mg of a pain killing drug to metastatic bone pain, and associated side effects, were assessed. The experimental design was a double-blind cross over clinical trial involving 44 patients known to suffer from metastatic bone pain. Each patient received the active drug in one of two dosages and the placebo in a random order, each lasting about 14 consecutive days. The data consisted of daily measurements of several pain and side effect variables. A few covariates were available. It was found that the patient and the investigator achieved a high degree of agreement on the blinded preference of the active drug to the placebo. A multivariate analysis of variance (MANOVA) on three different summary scores (mean, median, trmean) calculated on the daily measurements for which the patient received the active drug and on those for which the patient received the placebo was conducted. It was found that for the group of pain variables the order of application and the treatment do not have a significant effect marginally, but that they interact significantly. Variation between subjects was also significant. For the group of side effect variables, however, only significant variation between subjects was found. This suggests that the drug does not have noticeable overall side effects. To account for correlations among the response measurements within each patient, the methodology of generalized estimating equations was used to assess the significance of the effects of the predictors. Although the results are less reliable as they depend on the asymptotic behaviour of statistics, it was found that regardless of the level of correlation within patient response measurements, only the interaction of order of application with treatment has a significant effect on each of the pain variables. All the statistical analyses were carried out using Minitab, SAS, Matlab and Splus. / Thesis / Master of Science (MS)

Background: Many randomized controlled trials (RCTs) and meta-analyses include analyses of effect modification (also known as subgroup, interaction, or moderation analyses). Methodologists have widely acknowledged the challenges in deciding whether an apparent effect modification is credible or likely the result of chance or bias. Various sets of credibility criteria are available (Chapter 2 provides an example) but are inconsistent, vague in wording, lack guidance for deciding on overall credibility, and have not been systematically tested. Objective: To systematically develop a formal instrument to assess the credibility of effect modification analyses (ICEMAN) in RCTs and meta-analyses of RCTs. Methods: Key steps in the development process included 1) a systematic survey of the literature to identify available criteria, rationales, and previous instruments, 2) a formal consensus study among 10 leading experts, and 3) a formal user-testing study to refine the instrument based on interviews with trial investigators, systematic reviewer authors, and journal editors who applied drafts of the instrument to published claims of effect modification. Results: The systematic survey identified 150 relevant publications, 36 candidate credibility criteria with associated rationales, and 30 existing checklists (Chapter 3). The consensus study consisted of two main video conferences and multiple rounds of written discussion. The user-testing involved 17 users (including systematic review authors, trial investigators, and journal editors) who suggested substantial improvements based on detailed interviews. The final instrument provides separate versions for RCTs (five core questions) and meta-analyses (eight core questions) with explicit response options, and an overall credibility rating ranging from very low to high credibility. A detailed manual provides rationales, supporting references, examples from the literature, and suggestions for use in combination with other quality appraisal tools and reporting (Chapter 4). Discussion: ICEMAN is a rigorously developed instrument to evaluate claims of effect modification and addresses the main limitations of previous approaches. / Thesis / Doctor of Philosophy (PhD) / Randomized controlled trials and meta-analyses provide the best available evidence to evaluate whether effects of a therapy vary among individual patients. Efforts to decide whether treatment effects differ across patients are important and frequently done but difficult to interpret. The fundamental challenge is to decide whether apparent differences in effect are real or due to chance. To aid this decision, experts have suggested various sets of credibility criteria, all with important limitations. This thesis documents how we systematically addressed the limitations of previous approaches. Key steps were a systematic survey of the available credibility criteria, a consensus study among leading methodologists, and a formal user-testing study. The result is a new instrument for assessing the credibility of effect modification analyses (ICEMAN).

Traumatic brain injury (TBI) is a major medical concern that has demonstrated to be particularly challenging to treat because of the disparity amongst injury modes and severities. Increased use of explosive devices during combat has caused blast TBI (bTBI) to become a widespread consequence in military and Veteran populations, and impact-related trauma from contact-related sports or motor vehicle accidents has made mild impact-induced TBIs (concussion) a major health problem. There is a high risk for those who have sustained a TBI to develop behavioral and cognitive disorders following injury, and these symptoms can present as delayed onset, causing diagnosis to be a major feat when planning for treatment and long-term healthcare. Both preclinical and clinical studies report the neuropathological changes following TBI, yet investigating the distinct mechanistic changes in blast and impact trauma that contribute to pathological disparities has yet to be elucidated. Microglia dynamics play a key role in initiating the inflammatory response after injury, as microglia become activated by undergoing morphological changes that influence their function in the injured brain, and unique signaling pathways influence their functional inflammatory states. While previous literature report on the unique responses of microglia, their mediated-inflammatory responses are still not well defined. This work aimed to investigate the acute and subacute responses of microglia to injury through their diverse activation states following blast and impact trauma. The work herein employed rodent models to investigate these changes, finding that microglia activation was spatially and temporally heterogeneous within and across injury paradigms. Three days following bTBI, activated microglia in the cortex displayed morphologies similar to microglia that are known to increase their interactions with dysfunctional synapses, while dystrophic microglia were prevalent in the hippocampus seven days following injury. Moreover, transhemispheric changes in microglia activation were noted following impact TBI, with stressed/primed microglia responding to immune challenges of the cortex at three days, whereas a unique morphological state that was markedly different from those traditionally reported in CNS injury and disease was present within the hippocampus three- and seven-days following injury. State-of-the-art cell sorting techniques were used for in vivo analysis of microglia, which also exhibited that functional changes of microglia vary between injury paradigms, providing insight into how differences in primary insult may elicit distinct signaling pathways involved in microglia-mediated inflammatory responses. These in vivo studies were then crucial in understanding the malleable responses of microglia to complex injuries such as "blast plus impact" TBI, indicating that phenotypic changes in microglia following this injury are also unique and spatially heterogeneous. To date, therapeutic efforts for TBI are limited due to the lack of understanding the underlying mechanisms that influence TBI pathology. This work also investigated novel therapeutic targets, noting that administration of polyester nanoparticles restored microglia to baseline levels following impact. The fundamental research presented in this study is innovative and advantageous as it can provide essential data into targeted and personalized treatments that can improve long-term healthcare and ultimately, the quality of life for those suffering from a TBI. / Doctor of Philosophy / Traumatic brain injury (TBI) is a major medical concern that has demonstrated to be particularly challenging to treat because of the differences in injury modes and severities. Increased use of explosive devices during combat has caused blast TBI (bTBI) to become a widespread result in military and Veteran populations, and impact-related trauma from contact sports or motor vehicle accidents has made mild impact-induced TBIs (concussion) a major health problem. There is a high risk for those who have sustained a TBI to develop behavioral and cognitive disorders following injury, and these symptoms can present later on, causing diagnosis to be a major feat when planning for treatment and long-term healthcare. Microglia play a key role in inducing the inflammatory response after injury, as they change shape and size, which then influences their function in the injured brain. Although prior research reports on the unique responses of microglia, their effects on inflammation following TBI are still not well defined. This work aimed to investigate the early responses of microglia to injury through their diverse activation states following blast and impact trauma. The experiments in this study used animal models, finding that microglia activation can be distinct across time and brain regions, which may be injury-type-specific. To date, therapeutic efforts of TBI are limited due to the lack of understanding the underlying mechanisms that influence TBI pathology. This work also investigated beneficial treatments for TBI, noting that administration of nanoparticles helped restore microglia to levels similar to the control group. The fundamental research presented in this study is innovative and important as it can provide essential data into targeted and personalized treatments that can improve long-term healthcare and ultimately the quality of life for those suffering from a TBI.

Period 2 (Per2) is a core circadian factor responsible for its own negative regulation. It operates in the circadian clock, which affects multiple biological functions such as metabolic rate, hormone release, and core body temperature. The Per2 protein functions directly with factors in other biological functions such as tumor suppression, immune system, and metabolism. In many cases, the Per2 deficiency caused by disrupted expression is sufficient to create severe abnormalities in many of the mentioned functions. The sequence contains several domains and motifs in Per2 that are traditionally involved in protein interactions which suggests that Per2 serving a regulatory role by effecting downstream biological roles dependent on Per2 stability. In this work, we perform a two-hybrid screening assay using the C-terminal region of human Per2 and identified an extensive number of interactors. Utilizing a genetic ontology program, we assorted the list of clones into groups of proteins that are biologically relevant or operated in similar function. Through this program, we validated the two-hybrid screening by the clusters of biological function already attributed to hPer2 and identified new putative biological functions. We use the new putative interactors to gain further insight on the regulatory roles that hPer2 performs, in conjunction with operating as a core factor in circadian rhythmicity. We also show that Translationally Controlled Tumor Protein (TCTP) is capable of binding to hPer2 and is a novel interaction. When a sufficient amount of TCTP (1:1 molar stoichiometric ratio) is present in a system, a cleavage of hPer2 is observed in vitro. This cleavage occurs in reactions independent of ATP, ubiquitin, and the proteasome. The data points towards a method of cleavage similar to that of the archael lon-tk (Thermococcus kodakaraensis) that preferentially cleaved unstructured substrates in ATP-independent reactions. / Master of Science