Master of Science, The Ohio State University, 2020, Environment and Natural Resources

Aminomethylphosphonic acid (AMPA) is a microbial degradation product of the herbicide glyphosate, and industrial phosphonates. In addition to possible negative effects on human health, AMPA may inhibit soil microbial growth and alter the soil microbial community composition. Strong soil adsorption causes AMPA to persist in the environment, slowing degradation, and making AMPA a possible long-term environmental contaminant. Review of the research literature in Chapter 1 revealed knowledge gaps concerning the effects of AMPA on soil microorganisms in different soil types and in isolation from glyphosate. Although there have been many studies on the behavior and effects of glyphosate in different soil types, there is scarce data that isolates the effects of AMPA. Therefore, the research objectives were to (1) study the effects of AMPA on soil microorganisms, (2) investigate how soil type affects AMPA bioavailability, (3) determine if chemical extractability can be used to predict AMPA bioavailability, and (4) investigate AMPA in isolation from glyphosate. Based on the literature, the hypotheses were that (1) a higher concentration of AMPA would be found to have a greater effect on soil microorganisms, and (2) bioavailability would be less in soils with high clay, high iron and aluminum oxides, and low pH. Chapter 2 describes a 139-day incubation study on three diverse soils with no exposure to glyphosate. These soils included a sandy soil, and two high clay soils with different mineralogy. Three field relevant concentrations of AMPA, including the control, were applied directly to soil, and the effects of AMPA on soil microbial respiration and phospholipid fatty acids were analyzed. Chapter 3 describes an investigation of AMPA bioavailability using chemical extraction, and correlations of extractable AMPA with microbial responses. Total soil carbon and pH appeared to be the most important soil factors affecting response to AMPA. Based on PLFA results, AMPA w (open full item for complete abstract)

Committee: Richard Dick PhD (Advisor); Jeffory Hattey PhD (Committee Member); Roman Lanno PhD (Committee Member) Subjects: Environmental Health; Environmental Science; Microbiology; Soil Sciences

Doctor of Philosophy, Case Western Reserve University, 2018, Physiology and Biophysics

Peripheral organ injuries serve as potent stimuli for the immune system, triggering local inflammatory activation that can become increasingly amplified as the injury progresses, this in turn can lead to a severe systemic immune activation, which wreaks havoc over physiologic function. This is exemplified by lung injury, which can induce failure of multiple organ systems, or cause profound disruptions to brain function. When lung injury occurs in perinatal settings it may induce developmental impairments that last into adulthood. Here, using an experimental model of lung injury I investigated the mechanisms responsible for altering brainstem control of cardiorespiratory function in neonatal and adult rats. In neonatal rats, I determined that when lung injury is induced just before a transition period for the neural control of breathing (spanning P11-15), it promotes: i) an increase to the number of apnea directly preceded by a sigh, and ii) depression of viscerosensory synaptic transmission to 2nd-order neurons located in the nucleus tractus solitarii (nTS). This depression occurs through a postsynaptic mechanism that increases the contribution of Ca2+-impermeable (CI) AMPA receptors, and is mediated by the immune response to lung injury; minocycline, an inhibitor of microglia/macrophage activation, prevented the lung injury dependent increase in post-sigh apnea and the CI-AMPAR mediated synaptic depression. In rat-pups that were injured just after the transition period, viscerosensory synaptic transmission was also depressed, but occurred in a CI-AMPAR independent manner that contrastingly was presynaptically mediated. Thus, discrete mechanisms are responsible for these synaptic changes. In adult rats, where lung injury also increased the frequency of post-sigh apnea, I determined a novel immune-to-brain communication (I¿Bc) pathway utilized by the injury, which involves the glial-barrier separating the area postrema (a circumventricular organ) from the imm (open full item for complete abstract)

Committee: Frank Jacono M.D. (Advisor); George Dubyak Ph.D. (Committee Chair); Corey Smith Ph.D. (Committee Member); Thomas Dick Ph.D. (Committee Member); Roberto Galan Ph.D. (Committee Member) Subjects: Biophysics; Neurobiology; Physiology

Master of Science, The Ohio State University, 2018, Environment and Natural Resources

The herbicide glyphosate (N-(phosphonomethyl) glycine) was first introduced in 1974 as a non-selective, broad spectrum, post-emergent agrochemical, branded under the trade name Roundup® and intended to control weed competition in agricultural farming. It gained large popularity and increased usage in 1996 with the introduction of glyphosate resistant soybean (Glycine max) cultivars and again in 1998 with resistant corn (Zea mays) cultivars. Its widespread usage has increased the concern of unknown long-term effects on the soil rhizosphere microbial community. In the same long-term context there is also increased concern over glyphosate's toxicity and accumulation of degradation products, notably aminomethylphosphponic acid (AMPA), which accounts for the majority of detected metabolites in the soil. Chapter one of this thesis will review the current literature on the toxicity and degradability of glyphosate and AMPA in the soil. In chapter two of this thesis a long-term glyphosate greenhouse experiment was designed with two main objectives, (1) determine the effects of long-term glyphosate application for three different glyphosate formulations on glyphosate resistant (GR) soybean rhizosphere microbial communities of two different soil managements, one with and one without a history of glyphosate exposure, and (2) use stable isotope probing (SIP) to identify possible glyphosate degrading microbial functional groups in these two soil managements. The objective of chapter three was to expand on chapter two by investigating the accumulation of glyphosate and AMPA in both the rhizosphere and bulk soil of the same long-term glyphosate greenhouse experiment. Research from a greenhouse study showed that repeated application of glyphosate increased the abundance of gram-negative microorganisms relative to a single application as detected by FAMEs. Likewise a field study also showed that repeated application of glyphosate increased Fusarium fungal colonization on both corn an (open full item for complete abstract)

Committee: Richard Dick (Advisor) Subjects: Agricultural Chemicals; Agriculture; Microbiology; Soil Sciences

PHD, Kent State University, 2016, College of Arts and Sciences / Department of Psychological Sciences

Anxiety disorders are the most common mental disorder with nearly 30% of individuals meeting criteria for an anxiety disorder over the course of their lifetime, generating significant personal, financial and emotional burden. Additionally, women are 60% more likely than men to be diagnosed with an anxiety disorder, such as PTSD. Inappropriate fear that occurs in normally safe environments, or fear generalization, is a key symptom of many anxiety disorders. The current set experiments explores sex differences in the generalization of fear and identifies mechanisms by which estradiol affects fear generalization. Results demonstrate that females generalize fear at a faster rate than males, and this process is driven, in part, by estradiol. However, in males, estradiol acts to attenuate generalization rather than to induce generalization. In fact, testosterone also attenuates generalization in gonadectomized males and does so through conversion into estradiol via aromatase. Estradiol impacts generalization through effects on memory retrieval rather than memory acquisition/consolidation. In females, estradiol acts through activation of cytosolic ERß within the dorsal CA1 region of the hippocampus and the anterior cingulate cortex (ACC), but not the ventral CA1 region of the hippocampus. Finally, estradiol-induced generalization in females appears to be a result of augmented glutamatergic signaling within the dorsal CA1 and ACC; blocking glutamate receptor activation attenuates estradiol-induced generalization. These mechanisms can help explain the discrepancies in prevalence rates for anxiety disorders between males and females, and are also crucial for development of more effective, and potentially sex-specific, treatments for anxiety disorders such as PTSD.

Committee: Aaron Jasnow Ph.D (Advisor); David Riccio Ph.D (Advisor); Stephen Fountain Ph.D (Committee Member); Karin Coifman Ph.D (Committee Member); John Johnson Ph.D (Committee Member); Heather Caldwell Ph.D (Committee Chair) Subjects: Animals; Behavioral Psychology; Biology; Endocrinology; Experimental Psychology; Neurobiology; Pharmacology

Doctor of Philosophy (PhD), Wright State University, 2014, Biomedical Sciences PhD

The nervous system is faced with perturbations in activity levels throughout development and in disease or injury states. Neurons need to adapt to these changes in activity, but also need to maintain circuit firing within a normal range to stabilize the network from becoming too excited or too depressed. Homeostatic synaptic plasticity, the compensatory increase or decrease in synaptic strength as a result of excessive circuit inhibition or excitation, is a mechanism that the nervous system utilizes to keep network activity at normal levels. Despite intense effort, little is known about the mechanisms underlying homeostatic synaptic plasticity. Numerous studies have implicated postsynaptic modulation of AMPA receptors, but disagreement exists as to which receptor subtype, GluR1 or GluR2, predominates. Here, we demonstrate the completely novel finding that a presynaptic protein, Rab3A, a small GTPase that binds synaptic vesicles by switching between its active GTP-bound form and its inactive GDP-bound form, is essential for the regulation of homeostatic synaptic plasticity in dissociated mouse cortical neuron cultures. Using a combination of electrophysiology, pharmacology, and immunohistochemistry, we show that multiple mechanisms exist to increase synaptic strength in response to chronic activity deprivation, including but not limited to modulation of GluR1 and GluR2-containing AMPA receptors. Despite the variability and complexity of underlying mechanisms mediating the change in synaptic strength, we consistently found that modulation of synaptic strength in response to chronic network activity deprivation was completely lost in the absence of neuronal Rab3A, and that loss of Rab3A prevented the homeostatic increase in GluR2 levels but not GluR1. We conclude that there exist a biphasic mechanism for homeostatic synaptic plasticity, as suggested for LTP, where the induction (Phase 1) of the homeostatic increase in synaptic strength is first due to increasing GluR1 (open full item for complete abstract)

Committee: Kathrin Engisch Ph.D. (Advisor); Mark Rich M.D./Ph.D. (Committee Member); David Ladle Ph.D. (Committee Member); F. Javier Alvarez-Leefmans M.D./Ph.D. (Committee Member); Lynn Hartzler Ph.D. (Committee Member) Subjects: Biomedical Research; Neurobiology; Neurosciences; Physiology

Doctor of Philosophy, The Ohio State University, 2012, Neuroscience Graduate Studies Program

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the Central Nervous System (CNS). About 80% of MS patients start the disease as a form of Relapsing Remitting MS (RRMS) that is characterized by frequent inflammatory attacks followed by spontaneous recovery. However, about 10 years after disease onsite, 50% of the patients enter into secondary progressive MS (SPMS). At this stage, inflammation is limited, however, neurological decline continues. Therefore, both dysregulated immune function and neurodegeneration seem to contribute to the pathogenesis of MS. Clinical trials showed that Dimethyl Fumarate (DMF), a novel oral treatment for MS, significantly reduced gadolinium enhancing lesions in Relapsing-Remitting MS (RRMS). The safety record, efficacy and oral availability of DMF makes it potentially more beneficial to MS patients than currently available therapies. Yet, neither the molecular mechanism nor the potential neuroprotective effect of DMF has been fully investigated. One interesting observation from the Phase II clinical trial was a reduction in IFN-γ producing CD4+ T cells (Th1) in fumarate treated patients. Because Th1 cells are considered to be the pathogenic cells in MS, this clinical observation may have identified one mechanism of action of DMF. The first part of my graduate work was dedicated to understanding the cellular and molecular mechanism behind this clinical observation. Using dendritic cell generated both in vitro and in vivo, we demonstrate that DMF inhibits dendritic cell (DC) maturation by significantly reducing proinflammatory cytokine production and the expression of MHC class II, CD80 and CD86. Importantly, this immature DC phenotype generated fewer activated T cells that were characterized by decreased IFN-γ and IL-17 production. Further molecular studies demonstrate that DMF exerts its effects on DCs via suppression of both Nuclear Factor ¿¿¿¿B (NF-¿¿¿¿B) and Extracellular signal-Regulated Kinase 1 and 2 (ERK1/2) (open full item for complete abstract)

Committee: Michael Racke (Advisor); Dana McTigue (Committee Member); Gary Wenk (Committee Member); Jonathan Godbout (Committee Member) Subjects: Neurobiology

Doctor of Philosophy, The Ohio State University, 2007, Neuroscience

Spinal cord injury (SCI) is a long lasting, debilitating condition with no cure. Cervical SCI is the most common form of human SCI, often leaving patients paralyzed with a 15-20 year decrease in life expectancy. The majority of animal SCI contusion models are focused on thoracic injury. SCI at this level results in deficits almost entirely due to white matter damage that disconnects the rostral nervous system from the caudal spinal cord. Damage at the cervical level is different; in addition to the disconnection, gray matter damage affects the neurons controlling the upper extremities and diaphragm. To investigate injury at the cervical level, we characterized a unilateral C5 cervical contusion model in rats. By examining six-week behavioral recovery after SCI, we demonstrated that functional deficits are dependent upon the severity of injury. Analysis of the histopathology revealed that behavioral consequences are a result of damage to both the gray and white matter. Unilateral injury provides within-subject controls and preserves bladder and respiratory function. Many treatments for experimental rat SCI improve behavioral and histological outcomes but have yet to be implemented after human SCI. Treatments must be safe and tested in clinically relevant models to move from animals to humans. We examined the effects of three different clinically acceptable drugs. Methlyprednisolone and minocycline have anti-inflammatory effects if given after injury. Topiramate blocks glutamate receptors and hence excitotoxicity, an important component of secondary injury. Minocycline and methylprednisolone treatment yielded no significant behavioral or histological improvements when tested after moderate-severe unilateral cervical contusion injury. Topiramate was first tested in a model of excitotoxicity and then after cervical SCI and was compared to NBQX, a standard AMPA-receptor antagonists used in animal models of disease. Both drugs preserved neurons after excitotoxic injury, b (open full item for complete abstract)

Committee: Jacqueline Bresnahan (Advisor) Subjects: Biology, Neuroscience

Master of Arts, Miami University, 2012, Psychology

Few studies have specifically looked at dorsal hippocampus (DH) subregion (CA1, CA3, dentate gyrus) involvement in trace fear conditioning. In the present study, rats received a bilateral cannulation targeting one of the three DH subregions. Following surgery, animals were trace conditioned. Forty-eight hours following training, rats received an infusion of the CNQX or vehicle. Ten minutes following the start of the infusion, rats were placed in a novel context for the tone test. Rats that received CNQX into the dentate gyrus froze significantly less to the tone than control rats. Rats that received CNQX into the CA1 or CA3 subregion showed no difference in freezing to the tone compared to controls. These data support a role for the dentate gyrus in the expression of trace fear conditioning. This is different from the pattern observed for context fear conditioning, suggesting dissociable processes within the DH for trace and context fear.

Committee: Jennifer Quinn PhD (Committee Chair); Stephen Berry PhD (Committee Member); Dragana Claflin PhD (Committee Member) Subjects: Biology; Neurobiology; Psychology; Zoology

Doctor of Philosophy in Biomedical Sciences (Ph.D.), University of Toledo, 2009, College of Medicine

BZ withdrawal can lead to adaptive modification of glutamatergic synaptic transmissionin hippocampal CA1 neurons. Two subtypes of glutamate receptors, AMPAR and NMDAR, showed different patterns of modification upon BZ withdrawal. The possible mechanisms and intrinsic relationship of these two receptors during BZ withdrawal were studied in this dissertation. AMPAR-mediated mEPSC amplitudes were increased 30% in CA1 neurons with a 2-fold increase in single-channel conductance. The potentiated AMPAR-mediated synaptic transmission was also manifested by an increased slope of the input-output curve. CaMKII's contribution to the potentiation was validated by pre-incubation of slices with the selective inhibitor, KN-93, or intracellular inclusion of AIP, both of which prevented the increases of AMPAR current amplitude and conductance. Increased NAS inhibition was consistent with synaptic incorporation of homomeric GluR1 AMPARs. In 1-day withdrawn rats, only GluR1 levels were increased in immunoblots of the PSD-enriched subcellular fraction from CA1 minislices consistent with increased mEPSC amplitude, but not conductance. In 2-day withdrawn rats, total, but not relative phospho-Thr286 CaMKII levels increased in the PSD-enriched subfraction in parallel with increased GluR1 and phospho-Ser831 GluR1 expression levels implying that CaMKII mediates AMPAR phosphorylation and increased channel conductance in FZP-withdrawn CA1 neurons. Whole-cell and field (f)EPSP recordings revealed that LTP expression, induced by low-intensity theta burst stimulation, was impaired in CA1 neurons from FZPwithdrawn rats although no memory deficits were detectable using a novelty preference paradigm. The findings suggest that synaptic insertion and subsequent CaMKII-mediated phosphorylation of homomeric GluR1 AMPARs might contribute to BZ withdrawalinduced potentiation of AMPARs analogous to mechanisms underlying activitydependent plasticity. NMDAR function was depressed during BZ withdrawal. The c (open full item for complete abstract)

Committee: Elizabeth Tietz Ph.D. (Committee Chair); John Greenfield M.D., Ph.D. (Committee Member); Linda Dokas Ph.D. (Committee Member); David Giovannucci Ph.D. (Committee Member); Howard Rosenberg M.D., Ph.D. (Committee Member) Subjects: Neurology; Pharmacology

Doctor of Philosophy in Medical Sciences (Ph.D.), University of Toledo, 2007, College of Graduate Studies

Clinicians require caution prescribing benzodiazepines for a prolonged period of time because of the development of functional tolerance and dependence. The objective of these dissertation studies was to evaluate the role of L-type VGCC in mediating glutamate receptors and GABAA receptor functional changes in the expression of benzodiazepine tolerance and dependence following a 1-week FZP oral treatment regimen in rats. Initially, AMPA receptor-mediated mEPSC amplitude in hippocampal CA1 neurons was evaluated in rats withdrawn from 1-week FZP administration, using whole-cell electrophysiological recordings, and was found to correlate with benzodiazepine withdrawal-anxiety in rats measured using an elevated plus-maze. A compensatory role of NMDA receptor functional down-regulation was further identified as a counterbalance to AMPA receptor-mediated neuronal hyper-excitation. Following pharmacological antagonism of NMDA receptor and VGCC function, a role for regulation of L-type VGCCs, but not NMDA receptors, in mediating enhanced AMPA receptor function and benzodiazepine withdrawal anxiety was identified. Further studies concentrated on the regulation of L-type VGCC function following chronic benzodiazepine administration using whole-cell voltage-clamp method. The temporal pattern of L-type VGCC functional regulation was evaluated following chronic benzodiazepine administration. The direct concentration- and use-dependent effect of the benzodiazepines to affect L-type VGCC currents was also investigated. Based on the evidence of L-type VGCC function changes and its role in mediating AMPA receptor synaptic plasticity following chronic FZP administration, the relation between L-type VGCC and GABA receptor was further explored. Pharmacological antagonism was again applied for investigating the role of L-type VGCC in mediating GABAA receptor function using whole-cell ctrophysiological recordings of GABAA receptor-mediated currents. GABAA receptor channel kinetics and sin (open full item for complete abstract)

Committee: Elizabeth Tietz (Advisor) Subjects: