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In Vitro Exploration of Functional Acrolein Toxicity with Cortical Neuronal Networks (open access)

In Vitro Exploration of Functional Acrolein Toxicity with Cortical Neuronal Networks

Acrolein is produced endogenously after traumatic brain injury (TBI) and is considered a primary mechanism for secondary damage occurring after TBI. We are using frontal cortex networks derived from mouse embryos and grown on microelectrode arrays in vitro to monitor the spontaneous activity of networks and the changes that occur after acrolein application. Networks exposed to acrolein exhibit a biphasic response profile. An initial increase in network activity, followed by a decrease to 100% activity loss in applications ≥ 50 µM. In applications below 50 µM, acrolein was not toxic but generated activity instability with coordinated but irregular population busts lasting for up to 6 days. The increase in activity preceding toxicity may be linked to a decrease in free spermine, a free radical scavenger that modulates Na+, K+, Ca+ channels as well as NMDA, Kainate, and AMPA receptors. Action potential wave shape analysis after 20 and 30 µM acrolein application revealed a concentration-dependent 15-33% increase in peak to peak amplitude within minutes after exposure. For the same concentrations of acrolein (50 µM), the time required to reach 100% activity loss (IT100) was longer in serum-free medium than in medium with 5% serum, in which IT100 values were reduced by …
Date: May 2018
Creator: Durant, Stormy R.
System: The UNT Digital Library
Autonomic Nerve Activity and Cardiovascular Function in the Chicken Embryo (Gallus gallus) (open access)

Autonomic Nerve Activity and Cardiovascular Function in the Chicken Embryo (Gallus gallus)

The goal of this study was to build on the historic use of the avian model of development and also to further the knowledge of autonomic nervous system (ANS) regulation of cardiovascular function in vertebrates. Vasoactive drugs sodium nitroprusside, a vasodilator and phenylephrine, a vasoconstrictor were used to study the correlation of cardiovascular function relationship with nerve activity, both sympathetic and parasympathetic (vagal). Additionally, ANG II was used to assess its effects on vagal inhibition. The present study shows that pharmacologically-induced hypertension is associated with a fall in mSNA, indicating that the capacity for sympathetic autonomic cardiovascular regulation is established by late incubation however, late-stage embryonic chickens did not show a significant increase in mSNA during hypotension. The hypotensive response of the embryo was not accompanied by the expected inhibition of vagal discharge; however a slight but insignificant reduction in vagal discharge was noted. When vagal efferent output was isolated, a significant drop in vagal efferent activity was noted in response to hypotension. The present study showed late-stage embryonic chickens lack a vagal response to hypertension in both efferent and sensory limbs. In this study, vagal discharge was reduced from baseline levels in response to Ang II. Collectively, the present …
Date: December 2018
Creator: Onyemaechi, Clinton
System: The UNT Digital Library
Superbursts: Investigation of Abnormal Paroxysmal Bursting Activity in Nerve Cell Networks In Vitro (open access)

Superbursts: Investigation of Abnormal Paroxysmal Bursting Activity in Nerve Cell Networks In Vitro

Superbursts (SBs) are large, seemingly spontaneous activity fluctuations often encountered in high density neural networks in vitro. Little effort has been put forth to define and analyze SBs which are paroxysmal bursting discharges. Through qualitative and quantitative means, I have described specific occurrences of superbursting activity. A complex of paroxysmal bursting has been termed a "superburst episode," and each individual SB is a "superburst event" which is comprises a fine burst structure. Quantitative calculations (employing overall spike summations and coefficient of variation (CV) calculations), reveal three distinct phases. Phase 1 is a "build up" phase of increasingly strong, coordinated bursting with an average of a 17.6% ± 13.7 increase in activity from reference. Phase 2, the "paroxysmal" phase, is comprised of massive coordinated bursting with high frequency spike content. Individual spike activity increases by 52.9% ± 14.6. Phase 3 is a "recovery phase" of lower coordination and an average of a 50.1% ± 35.6 decrease in spike production from reference. SBs can be induced and terminated by physical manipulation of the medium. Using a peristaltic pump with a flow rate of 0.4ml/min, superbursting activity ceases approximately 28.3 min after the introduction of flow. Alternatively, upon cessation of medium flow superbursting …
Date: May 2018
Creator: Suri, Nikita
System: The UNT Digital Library
Isolation and Characterization of Phages Infecting Streptomyces azureus (open access)

Isolation and Characterization of Phages Infecting Streptomyces azureus

Isolating novel phages using Streptomyces azureus, which produces antibiotic thiostrepton, as a host, and characterizing the genomes may help us to find new tools that could be used to develop antibiotics in addition to contribute to the databases of phages and specifically, Streptomyces phages. Streptomyces phages Alsaber, Omar, Attoomi, Rowa, and ZamZam were isolated using during this study. They were isolated from enriched soil and sequenced by Illumina sequencing method. They were isolated from three different geographical regions. They are siphoviridae phages that create small clear plaques with a diameter of approximately 0.5-1 mm, except for Rowa which has cloudy plaques, and they have varied sizes of their heads and tails. ZamZam was not characterized at this time. The sequencing shows that they are circular genome with 3' sticky overhang and various genomes' sizes with high percentage of GC content with the average of 66%. Alsaber was classified under sub-cluster BD3, while Omar was categorized under sub-cluster BD2. They share the same cluster of Cluster BD. Rowa was placed in Cluster BL and Attoomi is currently a singleton that does not fit into an established cluster. Alsaber yields 76 putative genes with no tRNA, Omar 81 putative genes with 1 …
Date: May 2018
Creator: Sulaiman, Ahmad M.
System: The UNT Digital Library
Mass Spectrometry-Based Identification of Ceramic-Bound Archaeological Protein Residues: Method Validation, Residue Taphonomy, and Prospects (open access)

Mass Spectrometry-Based Identification of Ceramic-Bound Archaeological Protein Residues: Method Validation, Residue Taphonomy, and Prospects

Despite the variety of successful reports of the preservation, recovery, and identification of archaeological proteins in general, there are few positive reports regarding mass spectrometry-based identification of ceramic-bound proteins. In large part, this shortage is due to the lack of consideration for the unique taphonomic histories of such residues and, in general, methods development. Further, because negative results are rarely published, there is no baseline to which results can be compared. This paper attempts to address these challenges via a multi-pronged approach that uses mass spectrometry and complementary approaches to evaluate ceramic-bound protein preservation in both controlled, actualistic experiments, and in archaeological artifacts. By comparing the results obtained from protein-spiked, experimentally-aged ceramic to those obtained from both faunal and ceramic archaeological materials, an enhanced perspective on protein preservation and subsequent recovery and identification is revealed. This perspective, focusing on taphonomy, reveals why negative results may be the norm for ceramic artifacts when non-targeted methods are employed, and provides insight into how further method development may improve the likelihood of obtaining positive results.
Date: December 2018
Creator: Barker, Andrew Lewis
System: The UNT Digital Library
Key Factors Influencing Retention Rates among Historically Underrepresented Student Groups in STEM Fields (open access)

Key Factors Influencing Retention Rates among Historically Underrepresented Student Groups in STEM Fields

The aim of the study was to identify the factors that have an influence on the completion rates of undergraduate students in the fields of science, technology, engineering and mathematics (STEM). Using Tinto's retention rate theory as the theoretical foundation, data were collected from freshman who were enrolled in the years 2005 to 2008. Results showed gender and first-generation status were significant predictors of STEM completion and time taken to complete the degree. Institutional bias played a role in race/ethnicity not being a factor affecting completion rates, as this study was conducted at a Predominantly White Institution. SAT scores and first and second-year college GPA showed to have the most prominent influence on both STEM completion rate and time taken to complete the degree. Females with higher first-year college GPA and higher high school rank finished faster. Similar results were found with first-generation students as well. Students belonging to ethnic minority groups with higher SAT scores and college GPA had greater success in STEM fields as well. The study results can be used to increase completion rates of underrepresented students in the STEM fields, given what we know about the interactions between underrepresented student groups and the most important predictors.
Date: December 2018
Creator: Premraj, Divya
System: The UNT Digital Library
Population Dynamics and Community Structure of Mosquitoes (Diptera: Culicidae) Recorded in Denton, Texas from 2005 to 2015 (open access)

Population Dynamics and Community Structure of Mosquitoes (Diptera: Culicidae) Recorded in Denton, Texas from 2005 to 2015

A population survey was conducted on the mosquito species recorded in Denton, Texas for the years of 2005 to 2015. Data used in this project were obtained from an ongoing, long-term surveillance program led by the City of Denton and conducted through the University of North Texas. Research focused on the population dynamics and community structure of mosquitoes collected within urban areas of Denton, Texas in relation to certain environmental variables. A total of 80,837 female mosquitoes were captured and represented 38 species found under the following genera: Aedes, Anopheles, Coquillettidia, Culex, Culiseta, Mansonia, Orthopodomyia, Psorophora, Toxorhynchites, and Uranotaenia. Culex quinquefasciatus was the most abundant species followed by Aedes vexans. Seasonal patterns of the most abundant species revealed high variability throughout the study. Container breeders were most abundant in August and those that breed in floodwaters were most abundant in the months of May and September. Samples were tested for arbovirus presence through the Texas Department of State Health Services in Austin, Texas and multiple pools tested positive for West Nile virus throughout the study. Stepwise multiple regression and Spearman's rank correlation analyses were performed to examine the relationship between the mosquito community and environmental variables. Data revealed that temperature, …
Date: May 2018
Creator: Hambrick, Bethany Lynn
System: The UNT Digital Library
Compartmentalization of Jojoba Seed Lipid Metabolites (open access)

Compartmentalization of Jojoba Seed Lipid Metabolites

Seeds from the desert shrub Simmondsia chinensis (jojoba) are one of the only known natural plant sources to store a majority of its oil in the form of liquid wax esters (WE) instead of triacylglycerols (TAGs) and these oils account for ~55% of the seed weight. Jojoba oil is highly valued as cosmetic additives and mechanical lubricants, yet despite its value much is still unknown about its neutral lipid biosynthetic pathways and lipid droplet packaging machinery. Here, we have used a multi-"omics" approach to study how spatial differences in lipid metabolites, gene expression, and lipid droplet proteins influence the synthesis and storage of jojoba lipids. Through these studies mass spectrometry analyses revealed that WEs are compartmentalized primarily in the cotyledonary tissues, whereas TAGs are, surprisingly, localized to the embryonic axis tissues. To study the differences in gene expression between these two tissues, a de novo transcriptome was assembled from high throughput RNAseq data. Differential gene expression analysis revealed that the Jojoba Wax Synthase, which catalyzes the formation of wax esters, and the Diacylglycerol O-Acyltransferase1, which catalyzes the final acylation of triacylglycerol synthesis, were differentially expressed in the cotyledons and embryonic axis tissues, respectively. Furthermore, through proteomic analysis of lipid droplet …
Date: December 2018
Creator: Sturtevant, Drew
System: The UNT Digital Library
Optimization of In Vitro Mammalian Blastocyst Development: Assessment of Culture Conditions, Ovarian Stimulation and Experimental Micro-Manipulation (open access)

Optimization of In Vitro Mammalian Blastocyst Development: Assessment of Culture Conditions, Ovarian Stimulation and Experimental Micro-Manipulation

Factors currently at the forefront of human in vitro fertilization (IVF) that collectively influence treatment success in the form of blastocysts development were investigated during early mammalian embryology with concentration on infertile patients presenting with diminished ovarian reserve or preliminary ovarian failure. A novel experimental technique, Graft Transplant-Embryonic Stem Cells (GT-ESC) was introduced in the mouse model, as the first inclusive approach for embryo selection in IVF treatments resulting in successful graft integration of sibling cells, stage-dependent (day 4) blastocysts. E-Cadherin-catenin bonds play an integral role in trophectoderm cell viability and calcium removal, inducing disruption of cell-to-cell bonds at the blastocyst stage was detrimental to continued blastocyst development. One of the leading methods for embryo selection for uterine transfer in human IVF is application of pre-implantation genetic screening (PGS) methods such as next generation sequencing (NGS). Female patients <35 y do not benefit from this treatment when outcome is measured by presence of fetal heart beats at 10 weeks of gestation. Patients 35-37 y benefit from PGS with no significant difference of outcome based on form of PGS method utilized. Therefore, small nucleotide polymorphism array (snp-array) or targeted-NGS should be selected for this age range to lessen the financial burden …
Date: May 2018
Creator: Sadruddin, Sheela
System: The UNT Digital Library
Estimating Postmortem Interval Using VNIR Spectroscopy on Human Cortical Bone (open access)

Estimating Postmortem Interval Using VNIR Spectroscopy on Human Cortical Bone

Postmortem interval (PMI) estimation is a necessary but often difficult task that must completed during a death investigation. The level of difficulty rises as time since death increases, especially with the case of skeletonized remains (long PMI). While challenging, a reliable PMI estimate may be of great importance for investigative direction and cost-savings (e.g. suspect identification, tailoring missing persons searches, non-forensic remains exclusion). Long PMI can be estimated by assessing changes in the organic content of bone (i.e. collagen), which degrades and is lost as the PMI lengthens. Visible-near infrared (VNIR) spectroscopy is one method that can be used for analyzing organic constituents, including proteins, in solid specimens. A 2013 preliminary investigation using a limited number of human cortical bone samples suggested that VNIR spectroscopy could provide a fast, reliable technique for assessing PMI in human skeletal remains. Clear separation was noted between "forensic" and "archaeological" specimen spectra within the near-infrared (NIR) bands. The goal of this research was to develop reliable multivariate classification models that could assign skeletal remains to appropriate PMI classes (e.g. "forensic" and "non-forensic"), based on NIR spectra collected from human cortical bone. Working with a large set of cortical samples (n=341), absorbance spectra were collected …
Date: May 2018
Creator: Servello, John A.
System: The UNT Digital Library