Matching Items (73)
Description
Following a traumatic brain injury (TBI) 5-50% of patients will develop post traumatic epilepsy (PTE). Pediatric patients are most susceptible with the highest incidence of PTE. Currently, we cannot prevent the development of PTE and knowledge of basic mechanisms are unknown. This has led to several shortcomings to the treatment of PTE, one of which is the use of anticonvulsant medication to the population of TBI patients that are not likely to develop PTE. The complication of identifying the two populations has been hindered by the ability to find a marker to the pathogenesis of PTE. The central hypothesis of this dissertation is that following TBI, the cortex undergoes distinct cellular and synaptic reorganization that facilitates cortical excitability and promotes seizure development. Chapter 2 of this dissertation details excitatory and inhibitory changes in the rat cortex after severe TBI. This dissertation aims to identify cortical changes to a single cell level after severe TBI using whole cell patch clamp and electroencephalogram electrophysiology. The work of this dissertation concluded that excitatory and inhibitory synaptic activity in cortical controlled impact (CCI) animals showed the development of distinct burst discharges that were not present in control animals. The results suggest that CCI induces early "silent" seizures that are detectable on EEG and correlate with changes to the synaptic excitability in the cortex. The synaptic changes and development of burst discharges may play an important role in synchronizing the network and promoting the development of PTE.
ContributorsNichols, Joshua (Author) / Anderson, Trent (Thesis advisor) / Neisewander, Janet (Thesis advisor) / Newbern, Jason (Committee member) / Arizona State University (Publisher)
Created2014
Description
Postnatal skeletal muscle repair is dependent on the tight regulation of an adult stem cell population known as satellite cells. In response to injury, these quiescent cells are activated, proliferate and express skeletal muscle-specific genes. The majority of satellite cells will fuse to damaged fibers or form new muscle fibers, while a subset will return to a quiescent state, where they are available for future rounds of repair. Robust muscle repair is dependent on the signals that regulate the mutually exclusive decisions of differentiation and self-renewal. A likely candidate for regulating this process is NUMB, an inhibitor of Notch signaling pathway that has been shown to asymmetrically localize in daughter cells undergoing cell fate decisions. In order to study the role of this protein in muscle repair, an inducible knockout of Numb was made in mice. Numb deficient muscle had a defective repair response to acute induced damage as characterized by smaller myofibers, increased collagen deposition and infiltration of fibrotic cells. Satellite cells isolated from Numb-deficient mice show decreased proliferation rates. Subsequent analyses of gene expression demonstrated that these cells had an aberrantly up-regulated Myostatin (Mstn), an inhibitor of myoblast proliferation. Further, this defect could be rescued with Mstn specific siRNAs. These data indicate that NUMB is necessary for postnatal muscle repair and early proliferative expansion of satellite cells. We used an evolutionary compatible to examine processes controlling satellite cell fate decisions, primary satellite cell lines were generated from Anolis carolinensis. This green anole lizard is evolutionarily the closet animal to mammals that forms de novo muscle tissue while undergoing tail regeneration. The mechanism of regeneration in anoles and the sources of stem cells for skeletal muscle, cartilage and nerves are poorly understood. Thus, satellite cells were isolated from A. carolinensis and analyzed for their plasticity. Anole satellite cells show increased plasticity as compared to mouse as determined by expression of key markers specific for bone and cartilage without administration of exogenous morphogens. These novel data suggest that satellite cells might contribute to more than muscle in tail regeneration of A. carolinensis.
ContributorsGeorge, Rajani M (Author) / Wilson-Rawls, Jeanne (Thesis advisor) / Rawls, Alan (Committee member) / Whitfield, Kerr (Committee member) / Kusumi, Kenro (Committee member) / Arizona State University (Publisher)
Created2012
Description
Skeletal muscles arise from the myotome compartment of the somites that form during vertebrate embryonic development. Somites are transient structures serve as the anlagen for the axial skeleton, skeletal muscle, tendons, and dermis, as well as imposing the metameric patterning of the axial musculoskeletal system, peripheral nerves, and vasculature. Classic studies have described the role of Notch, Wnt, and FGF signaling pathways in controlling somite formation and muscle formation. However, little is known about the transformation of myotome compartments into identifiable post-natal muscle groups. Using a mouse model, I have undertaken an evaluation of morphological events, including hypertrophy and hyperplasia, related to the formation of several muscles positioned along the dorsal surface of the vertebrae and ribs. Lunatic fringe (Lfng) deficient embryos and neonates were also examined to further understand the role of the Notch pathway in these processes as it is a modulator of the Notch receptor and plays an important role in defining somite borders and anterior-posterior patterning in many vertebrates. Lunatic fringe deficient embryos showed defects in muscle fiber hyperplasia and hypertrophy in the iliocostalis and longissimus muscles of the erector spinae group. This novel data suggests an additional role for Lfng and the Notch signaling pathway in embryonic and fetal muscle development.
ContributorsDe Ruiter, Corinne (Author) / Rawls, J. Alan (Thesis advisor) / Wilson-Rawls, Jeanne (Committee member) / Kusumi, Kenro (Committee member) / Fisher, Rebecca E. (Committee member) / Arizona State University (Publisher)
Created2012
Description
The ability to detect and appropriately respond to chemical stimuli is important for many organisms, ranging from bacteria to multicellular animals. Responses to these stimuli can be plastic over multiple time scales. In the short-term, the synaptic strengths of neurons embedded in neural circuits can be modified and result in various forms of learning. In the long-term, the overall developmental trajectory of the olfactory network can be altered and synaptic strengths can be modified on a broad scale as a direct result of long-term (chronic) stimulus experience. Over evolutionary time the olfactory system can impose selection pressures that affect the odorants used in communication networks. On short time scales, I measured the effects of repeated alarm pheromone exposure on the colony-level defense behaviors in a social bee. I found that the responses to the alarm pheromone were plastic. This suggests that there may be mechanisms that affect individual plasticity to pheromones and regulate how these individuals act in groups to coordinate nest defense. On longer time scales, I measured the behavioral and neural affects of bees given a single chronic odor experience versus bees that had a natural, more diverse olfactory experience. The central brains of bees with a deprived odor experience responded more similarly to odorants in imaging studies, and did not develop a fully mature olfactory network. Additionally, these immature networks showed behavioral deficits when recalling odor mixture components. Over evolutionary time, signals need to engage the attention of and be easily recognized by bees. I measured responses of bees to a floral mixture and its constituent monomolecular components. I found that natural floral mixtures engage the orientation of bees’ antennae more strongly than single-component odorants and also provide more consistent central brain responses between stimulations. Together, these studies highlight the importance of olfactory experience on different scales and how the nervous system might impose pressures to select the stimuli used as signals in communication networks.
ContributorsJernigan, Christopher (Author) / Smith, Brian H. (Thesis advisor) / Newbern, Jason (Committee member) / Harrisoin, Jon (Committee member) / Rutowski, Ronald (Committee member) / Pratt, Stephen (Committee member) / Arizona State University (Publisher)
Created2018
Description
Parkinson’s disease (PD) is a progressive neurodegenerative disorder, diagnosed late in
the disease by a series of motor deficits that manifest over years or decades. It is characterized by degeneration of mid-brain dopaminergic neurons with a high prevalence of dementia associated with the spread of pathology to cortical regions. Patients exhibiting symptoms have already undergone significant neuronal loss without chance for recovery. Analysis of disease specific changes in gene expression directly from human patients can uncover invaluable clues about a still unknown etiology, the potential of which grows exponentially as additional gene regulatory measures are questioned. Epigenetic mechanisms are emerging as important components of neurodegeneration, including PD; the extent to which methylation changes correlate with disease progression has not yet been reported. This collection of work aims to define multiple layers of PD that will work toward developing biomarkers that not only could improve diagnostic accuracy, but also push the boundaries of the disease detection timeline. I examined changes in gene expression, alternative splicing of those gene products, and the regulatory mechanism of DNA methylation in the Parkinson’s disease system, as well as the pathologically related Alzheimer’s disease (AD). I first used RNA sequencing (RNAseq) to evaluate differential gene expression and alternative splicing in the posterior cingulate cortex of patients with PD and PD with dementia (PDD). Next, I performed a longitudinal genome-wide methylation study surveying ~850K CpG methylation sites in whole blood from 189 PD patients and 191 control individuals obtained at both a baseline and at a follow-up visit after 2 years. I also considered how symptom management medications could affect the regulatory mechanism of DNA methylation. In the last chapter of this work, I intersected RNAseq and DNA methylation array datasets from whole blood patient samples for integrated differential analyses of both PD and AD. Changes in gene expression and DNA methylation reveal clear patterns of pathway dysregulation that can be seen across brain and blood, from one study to the next. I present a thorough survey of molecular changes occurring within the idiopathic Parkinson’s disease patient and propose candidate targets for potential molecular biomarkers.
the disease by a series of motor deficits that manifest over years or decades. It is characterized by degeneration of mid-brain dopaminergic neurons with a high prevalence of dementia associated with the spread of pathology to cortical regions. Patients exhibiting symptoms have already undergone significant neuronal loss without chance for recovery. Analysis of disease specific changes in gene expression directly from human patients can uncover invaluable clues about a still unknown etiology, the potential of which grows exponentially as additional gene regulatory measures are questioned. Epigenetic mechanisms are emerging as important components of neurodegeneration, including PD; the extent to which methylation changes correlate with disease progression has not yet been reported. This collection of work aims to define multiple layers of PD that will work toward developing biomarkers that not only could improve diagnostic accuracy, but also push the boundaries of the disease detection timeline. I examined changes in gene expression, alternative splicing of those gene products, and the regulatory mechanism of DNA methylation in the Parkinson’s disease system, as well as the pathologically related Alzheimer’s disease (AD). I first used RNA sequencing (RNAseq) to evaluate differential gene expression and alternative splicing in the posterior cingulate cortex of patients with PD and PD with dementia (PDD). Next, I performed a longitudinal genome-wide methylation study surveying ~850K CpG methylation sites in whole blood from 189 PD patients and 191 control individuals obtained at both a baseline and at a follow-up visit after 2 years. I also considered how symptom management medications could affect the regulatory mechanism of DNA methylation. In the last chapter of this work, I intersected RNAseq and DNA methylation array datasets from whole blood patient samples for integrated differential analyses of both PD and AD. Changes in gene expression and DNA methylation reveal clear patterns of pathway dysregulation that can be seen across brain and blood, from one study to the next. I present a thorough survey of molecular changes occurring within the idiopathic Parkinson’s disease patient and propose candidate targets for potential molecular biomarkers.
ContributorsHenderson, Adrienne Rose (Author) / Huentelman, Matthew J (Thesis advisor) / Newbern, Jason (Thesis advisor) / Dunckley, Travis L (Committee member) / Jensen, Kendall (Committee member) / Wilson, Melissa (Committee member) / Arizona State University (Publisher)
Created2019
Description
Multicellular organisms use precise gene regulation, executed throughout development, to build and sustain various cell and tissue types. Post-transcriptional gene regulation is essential for metazoan development and acts on mRNA to determine its localization, stability, and translation. MicroRNAs (miRNAs) and RNA binding proteins (RBPs) are the principal effectors of post-transcriptional gene regulation and act by targeting the 3'untranslated regions (3'UTRs) of mRNA. MiRNAs are small non-coding RNAs that have the potential to regulate hundreds to thousands of genes and are dysregulated in many prevalent human diseases such as diabetes, Alzheimer's disease, Duchenne muscular dystrophy, and cancer. However, the precise contribution of miRNAs to the pathology of these diseases is not known.
MiRNA-based gene regulation occurs in a tissue-specific manner and is implemented by an interplay of poorly understood and complex mechanisms, which control both the presence of the miRNAs and their targets. As a consequence, the precise contributions of miRNAs to gene regulation are not well known. The research presented in this thesis systematically explores the targets and effects of miRNA-based gene regulation in cell lines and tissues.
I hypothesize that miRNAs have distinct tissue-specific roles that contribute to the gene expression differences seen across tissues. To address this hypothesis and expand our understanding of miRNA-based gene regulation, 1) I developed the human 3'UTRome v1, a resource for studying post-transcriptional gene regulation. Using this resource, I explored the targets of two cancer-associated miRNAs miR-221 and let-7c. I identified novel targets of both these miRNAs, which present potential mechanisms by which they contribute to cancer. 2) Identified in vivo, tissue-specific targets in the intestine and body muscle of the model organism Caenorhabditis elegans. The results from this study revealed that miRNAs regulate tissue homeostasis, and that alternative polyadenylation and miRNA expression patterns modulate miRNA targeting at the tissue-specific level. 3) Explored the functional relevance of miRNA targeting to tissue-specific gene expression, where I found that miRNAs contribute to the biogenesis of mRNAs, through alternative splicing, by regulating tissue-specific expression of splicing factors. These results expand our understanding of the mechanisms that guide miRNA targeting and its effects on tissue-specific gene expression.
MiRNA-based gene regulation occurs in a tissue-specific manner and is implemented by an interplay of poorly understood and complex mechanisms, which control both the presence of the miRNAs and their targets. As a consequence, the precise contributions of miRNAs to gene regulation are not well known. The research presented in this thesis systematically explores the targets and effects of miRNA-based gene regulation in cell lines and tissues.
I hypothesize that miRNAs have distinct tissue-specific roles that contribute to the gene expression differences seen across tissues. To address this hypothesis and expand our understanding of miRNA-based gene regulation, 1) I developed the human 3'UTRome v1, a resource for studying post-transcriptional gene regulation. Using this resource, I explored the targets of two cancer-associated miRNAs miR-221 and let-7c. I identified novel targets of both these miRNAs, which present potential mechanisms by which they contribute to cancer. 2) Identified in vivo, tissue-specific targets in the intestine and body muscle of the model organism Caenorhabditis elegans. The results from this study revealed that miRNAs regulate tissue homeostasis, and that alternative polyadenylation and miRNA expression patterns modulate miRNA targeting at the tissue-specific level. 3) Explored the functional relevance of miRNA targeting to tissue-specific gene expression, where I found that miRNAs contribute to the biogenesis of mRNAs, through alternative splicing, by regulating tissue-specific expression of splicing factors. These results expand our understanding of the mechanisms that guide miRNA targeting and its effects on tissue-specific gene expression.
ContributorsKotagama, Kasuen Indrajith Bandara (Author) / Mangone, Marco (Thesis advisor) / LaBaer, Joshua (Committee member) / Newbern, Jason (Committee member) / Rawls, Alan (Committee member) / Arizona State University (Publisher)
Created2019
Description
The current study investigated whether intermittent restraint stress (IRS) would impair fear extinction learning and lead to increased anxiety and depressive- like behaviors and then be attenuated when IRS ends and a post- stress rest period ensues for 6 weeks. Young adult, male Sprague Dawley rats underwent restraint stress using wire mesh (6hr/daily) for five days with two days off before restraint resumed for three weeks for a total of 23 restraint days. The groups consisted of control (CON) with no restraint other than food and water restriction yoked to the restrained groups, stress immediate (STR-IMM), which were restrained then fear conditioned soon after the end of the IRS paradigm, and stress given a rest for 6 weeks before fear conditioning commenced (STR-R6). Rats were fear conditioned by pairing a 20 second tone with a footshock, then given extinction training for two days (15 tone only on each day). On the first day of extinction, all groups discriminated well on the first trial, but then as trials progressed, STR-R6 discriminated between tone and context less than did CON. On the second day of extinction, STR- IMM froze more to context in the earlier trials than compared to STR-R6 and CON. As trials progressed STR-IMM and STR-R6 froze more to context than compared to CON. Together, CON discriminated between tone and context better than did STR-IMM and STR-R6. Sucrose preference, novelty suppressed feeding, and elevated plus maze was performed after fear extinction was completed. No statistical differences were observed among groups for sucrose preference or novelty suppressed feeding. For the elevated plus maze, STR-IMM entered the open arms and the sum of both open and closed arms fewer than did STR- R6 and CON. We interpret the findings to suggest that the stress groups displayed increased hypervigilance and anxiety with STR-R6 exhibiting a unique phenotype than that of STR-IMM and CON.
ContributorsShah, Vrishti Bimal (Author) / Conrad, Cheryl (Thesis director) / Newbern, Jason (Committee member) / Judd, Jessica (Committee member) / School of Life Sciences (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Alternative polyadenylation (APA) is the biological mechanism in which the same gene can have multiple 3'untranslated region (3'UTR) isoforms due to the presence of multiple polyadenylation signal (PAS) elements within the pre mRNAs. Because APA produces mRNA transcripts that have different 3'UTR isoforms, certain transcripts may be subject to post-transcriptional regulation by regulatory non-coding RNAs, such as microRNAs or RNA binding proteins defects of which have been implicated in diseases such as cancer. Despite the increasing level of information, functional understanding of the molecular mechanisms involved in transcription is still poorly understood, nor is it clear why APA is necessary at a cell or tissue-specific level. To address these questions I wanted to develop a set of sensor strain plasmids capable of detecting cleavage and polyadenylation in vivo, inject the complete sensor strain plasmid into C. elegans and prepare stable transgenic lines, and perform proof-of-principle RNAi feeding experiments targeting genes associated with the cleavage and polyadenylation complex machinery. I demonstrated that it was possible to create a plasmid capable of detecting cleavage and polyadenylation in C. elegans; however, issues arose during the RNAi assays indicating the sensor strain plasmid was not sensitive enough to the RNAi to effectively detect in the worms. Once the problems involved with sensitivity and variability in the RNAi effects are resolved, the plasmid would be able to better address questions regarding the functional understanding of molecular mechanisms involved in transcription termination.
ContributorsWilky, Henry Patrick (Author) / Mangone, Marco (Thesis director) / Newbern, Jason (Committee member) / Blazie, Stephen (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
This is a descriptive study looking at the management of patients with hypoplastic aortic arch and interrupted aortic arch, which are obstructive anomalies of the aortic arch. I will specifically be looking at patient specific factors such as chromosomal abnormalities and other comorbidities associated with aortic arch conditions as well as outcomes following aortic arch repairs.
ContributorsMenon, Tushar (Author) / Newbern, Jason (Thesis director) / Nigro, John (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Egr3 is an immediate early gene transcription factor that shows genetic association with schizophrenia, and is found in decreased levels in the brains of schizophrenia patients. Schizophrenia patients also exhibit cognitive and memory deficits, both of which Egr3 has been shown to play a crucial role in. Additionally, high levels of DNA damage are found in the brains of schizophrenia patients. A recent study has shown that DNA damage occurs as a result of normal physiological activity in neurons and is required for induction of gene expression of a subset of early response genes. Also, failure to repair this damage can lead to gene expression in a constitutive switched on state. Egr3 knockout (Egr3-/-) mice show deficits in hippocampal synaptic plasticity and memory. We were interested in characterizing downstream targets of EGR3 in the hippocampus. To determine these targets, electroconvulsive seizure (ECS) was carried out in Egr3 -/- versus wild type (WT) mice, and a microarray study was first done in our lab. ECS maximally stimulates Egr3 expression and we hypothesized that there would be gene targets that are differentially expressed between Egr3 -/- and WT mice that had been subjected to ECS. Two separate analyses of the microarray yielded 65 common genes that were determined as being differentially expressed between WT and Egr3 -/- mice after ECS. Further Ingenuity Pathway Analysis of these 65 genes indicated the Gadd45 signaling pathway to be the top canonical pathway, with the top four pathways all being associated with DNA damage or DNA repair. A literature survey was conducted for these 65 genes and their associated pathways, and 12 of the 65 genes were found to be involved in DNA damage response and/or DNA repair. Validation of differential expression was then conducted for each of the 12 genes, in both the original male cohort used for microarray studies and an additional female cohort of mice. 7 of these genes validated through quantitative real time PCR (qRT-PCR) in the original male cohort used for the microarray study, and 4 validated in both the original male cohort and an independent female cohort. Bioinformatics analysis yielded predicted EGR3 binding sites in promoters of these 12 genes, validating their role as potential transcription targets of EGR3. These data reveal EGR3 to be a novel regulator of DNA repair. Further studies will be needed to characterize the role of Egr3 in repairing DNA damage.
ContributorsBarkatullah, Arhem Fatima (Author) / Newbern, Jason (Thesis director) / Gallitano, Amelia (Committee member) / Marballi, Ketan (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05