UNT Theses and Dissertations - 234 Matching Results

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Impacts of the Pyrethroid Insecticide Cyfluthrin on Aquatic Invertibrate Populations in Outdoor Experimental Tanks

Description: The chemical fate and biological impacts of cyfluthrin in aquatic ecosystems were investigated using microcosms (1.9 m^3 concrete tanks) during 1989. Results were compared to a concurrent pesticide registration study using mesocosms (634.7 m^3 earthen ponds). Ten spray drift and five soil runoff simulations were conducted. Pesticide loadings were scaled by system volume, with the same experimental design in ponds and microcosms. Aqueous cyfluthrin concentrations and sediment residue values were… more
Date: May 1992
Creator: Johnson, Philip C. (Philip Charles)
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Partner: UNT Libraries
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Implications of Diet in Cardiovascular Disease Risk: Postprandial Changes in Circulating Monocytes and Endotoxemia

Description: It is well established that continual consumption of a diet high in fat leads to the development of chronic conditions such as obesity, cardio metabolic syndrome, and atherosclerosis that are associated with high incidence of cardiovascular disease. Recent studies have identified endotoxin-derived inflammation as a major diving force for the development of these conditions. Our laboratory has recently demonstrated that consumption of a single high-fat meal results in acute postprandial endotoxe… more
Date: August 2018
Creator: Venable, Andrea Henning
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Improving Processing Efficiency for Forensic DNA Samples

Description: The goal of this project was to reduce processing time for forensic DNA testing without incurring significant added costs and/or the need for new instrumentation, while still generating high quality profiles. This was accomplished by: 1) extraction normalization using the ChargeSwitch® Forensic DNA Purification Kit such that a small range of DNA concentrations was consistently obtained, eliminating the need for sample quantification and dilution; 2) developing fast PCR protocols for STR primer … more
Date: May 2015
Creator: Connon, Catherine Cupples
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In vitro Cultures of Morus alba for Enhancing Production of Phytoestrogens

Description: Plant estrogens have long been associated with health benefits. The potential of tissue culture techniques for the production of several secondary metabolites has been known for many years. Tissue cultures stimulate the production or induce the biosynthesis of novel compounds not found in the mature plant. Tissue culture of Morus alba, family Moraceae, is known to contain phytoestrogens, was established on plant-hormone supplemented Murashige and Skoog (MS) medium. Petiole and the stem tissue f… more
Date: December 2009
Creator: Bakshi, Vibhu
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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In Vivo and In Vitro Transformations of Mouse Tissues from a Murine Lymphosarcoma

Description: The problem with which this investigation is concerned is that of determining the nature of events leading to the change. of normal cells into malignant cells. The design of the study is multi-phasic: (A) to establish the presence or absence of an oncogenic virion, (B) to demonstrate by use of the electron microscopy any ultracellular alteration in malignant or transformed tissues, (C) to investigate the nature of the transforming agent in the murine lymphosarcoma, and (D) to employ various met… more
Date: August 1972
Creator: Carnes, James Edgar
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Incubation humidity as an environmental stressor on the osmoregulatory developmental program of the chicken, Gallus gallus domesticus.

Description: Fetal programming results from stressors during fetal development and may influence the occurrence of disease later in life. Maternal nutritional status and/or environment can affect renal development by inducing limited nephron endowment at birth, which results in diseases such as hypertension and coronary heart disease in mammals. Birds are likely to be effective models for this process because, like mammals, they have high pressure cardiovascular systems, mammalian-type nephrons and are ho… more
Date: August 2009
Creator: Bolin, Greta M.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Inferring a Network of Horizontal Gene Flow among Prokaryotes Using Complementary Approaches

Description: Horizontal gene transfer (HGT), a mechanism that facilitates exchange of genetic material between organisms from different lineages, has a profound impact on prokaryotic evolution. To infer HGT, we first developed a comparative genomics-based tool, APP, which can perform phyletic pattern analysis using completely sequenced genomes to identify genes are unique to a genome or have sporadic distribution in its close relatives. Performance assessment against currently available tools on a manually … more
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Date: August 2022
Creator: Sengupta, Soham
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Influence of a Return of Native Grasslands upon the Ecology and Distribution of Small Rodents in Big Bend National Park

Description: In the southwestern United States there is a delicate balance between the existing grasslands and the rodent fauna. The purpose of this investigation was to determine the influence of secondary succession of native grasslands upon the ecology and distribution of small rodents. Two methods of determining the rodent species were plot quadrates and trap lines using Sherman live traps.
Date: August 1971
Creator: Baccus, John T.
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Partner: UNT Libraries
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The Influence of in Vitro Gill and Liver Metabolism of Xenobiotics on Fish Bioconcentration

Description: This dissertation examines the ability of in vitro biotransformation assays to provide an indication of metabolic potential. The potential for xenobiotic compounds to bioconcentrate in aquatic organisms is expressed through the bioconcentration factor (BCF). The metabolic loss of ibuprofen, norethindrone and propranolol was measured using rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) gill and liver S9 fractions, microsomes and cell suspensions. Metabolic trans… more
Date: August 2010
Creator: Gomez, Cristi Frasier
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Partner: UNT Libraries
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Interactions between Carotid and Cardiopulmonary Baroreceptor Populations during Dynamic Exercise in Man

Description: During dynamic exercise the arterial baroreflexes have been thought to reset to the prevailing level of systemic pressure in order to modulate transient changes in blood pressure with the same sensitivity (gain) as at rest. To test this hypothesis, cardiovascular responses to dynamic exercise and carotid baroreflex responses to graded neck suction and neck pressure (NS/NP) were examined in seven men of moderate fitness (V02 = 41.4±3.6 ml O2*kg^-1*min^-1) during two levels (20% and 40% of peak o… more
Date: May 1993
Creator: Potts, Jeffrey Thomas
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Interactions between Carotid and Cardiopulmonary Baroreceptor Populations in Men with Varied Levels of Maximal Aerobic Power

Description: Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^… more
Date: August 1989
Creator: Pawelczyk, James A. (James Anthony)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Investigating the Effects of Inhaled Diesel Exhaust Particles on Gut Microbiome, Intestinal Integrity, Systemic Inflammation, and Biomarkers of Cardiovascular Disease in Wildtype Mice

Description: We investigated the hypothesis that exposure to inhaled diesel exhaust PM can alter the gut microbiome and intestinal integrity, thereby promoting systemic inflammatory response and early CVD risk, which are exacerbated by HF diet. Furthermore, we investigated whether the observed exposure and diet-mediated outcomes could be mitigated through probiotic treatment. We performed an exposure study on C57Bl/6 male mice, placed on either a low fat (LF) diet or a high-fat (HF) diet, and exposed via or… more
Date: December 2021
Creator: Phillippi, Danielle T.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Investigating the Effects of Traffic-Generated Air-Pollution on the Microbiome and Immune Responses in Lungs of Wildtype Mice

Description: There is increasing evidence indicating that exposure to air pollutants may be associated with the onset of several respiratory diseases such as allergic airway disease and chronic obstructive pulmonary disorder (COPD). Many lung diseases demonstrate an outgrowth of pathogenic bacteria belonging to the Proteobacteria phylum, and the incidence of occurrence of these diseases is higher in heavily polluted regions. Within the human body, the lungs are among the first to be exposed to the harmful e… more
Date: December 2020
Creator: Daniel, Sarah
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries

Investigating the Mechanisms involved in Traffic-Generated Air Pollution: Mediated Disruption of the Blood-Brain Barrier in a Wild Type Mouse Model using a Pharmaceutical Intervention Approach

Description: This study investigated whether oxLDL and/or angiotensin (Ang) II signaling pathways mediate traffic-generated air pollution- exposure induced alterations in blood-brain barrier (BBB) integrity and permeability in a healthy wild type (C57Bl/6) mouse model; additionally, whether these outcomes are exacerbated by a high fat-diet investigated. An environmentally relevant concentration of a mixture of vehicle engine exhaust (MVE) was used. To investigate the hypotheses, 12 wk old male C57Bl/6 mice… more
Date: August 2020
Creator: Suwannasual, Usa
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Investigation of Pyrimidine Salvage Pathways to Categorize Indigenous Soil Bacteria of Agricultural and Medical Importance and Analysis of the Pyrimidine Biosynthetic Pathway's Enzyme Properties for Correlating Cell Morphology to Function in All Phases of Growth

Description: This dissertation comprises three parts and is presented in two chapters. Chapter 1 concerns Arthrobacter, a bacterium with an intriguing growth cycle. Whereas most bacteria exist as either a rod or coccus, this bacterium shares the rod/coccus lifestyle. It therefore seemed important to examine the growth regulatory pathways from the rod and coccus. The committed step, that catalyzed by aspartate transcarbamoylase (ATCase), in the pyrimidine biosynthetic pathway was chosen. The ATCase in Arthr… more
Date: May 2003
Creator: Meixner, Jeffery Andrew
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Partner: UNT Libraries
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Investigations of neuronal network responses to electrical stimulation in murine spinal cultures.

Description: Spontaneous activity in neuronal networks in vitro is common and has been well documented. However, alteration of spontaneous activity in such networks via conditioning electrical stimulation has received much less experimental attention. Two different patterns of electrical stimulation were used to enhance or depress the level of spontaneous activity in spinal cord cultures. High-frequency stimulation (HFS), a method routinely shown to increase the efficacy of synaptic transmission, was employ… more
Date: December 2001
Creator: Sparks, Christopher A.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Isolation and Characterization of a Hitherto Undescribed Gram-Negative Bacterium

Description: A unique undosciribed gramnegative rod is extensively characterized in this study. The cells of this unusual water isolate measure 1.2 X 6.5 microns, The most distinguishing characteristic of the bacterium is a polar tuft of 35-40 flagella that aggregate to function as a single organelle which is visible under phase contrast. Aging cells deposit poly- -hydroxybutyric acid granules which are bound by an inclusion membrane made up of four distinct layers. It also possesses an unusual exterior mem… more
Date: August 1972
Creator: Lassiter, Carroll Benson
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Isolation and Characterization of a New Capsule-Forming Bacterium

Description: A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the op… more
Date: May 1999
Creator: Thongmee, Acharawan
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Isolation and Characterization of Malic Enzyme from Ascaris suum

Description: A procedure for the isolation of malic enzyme from muscle tissue of the roundworm Ascaris suum is described. The fractionation method yields relatively large quantities of the enzyme,with a specific activity of fifteen moles of malate converted to pyruvate and carbon dioxide per min per mg at 25º. Homogeneity was established with analytical ultracentrifugation, zone electrophoresis, isoelectric focusing, and rechromatography. The molecular weight of the enzyme was 250,000, and it is dissociated… more
Date: December 1972
Creator: Fodge, Douglas W.
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Isolation, Characterization and Physiological Studies of Cyanide-Utilizing Bacteria

Description: Ten bacteria capable of growth on the metal-cyano complex, tetracyanonickelate (II) {K2 [Ni(CN)J } (TCN), supplied as the sole nitrogen source, were isolated. Seven isolates were identified as pseudomonads while the remaining three were classified as Klebsiella species. In addition to TCN, all isolates were able to utilize KCN although it was significantly more toxic. The degradation of TCN was most complete when supplied at growth-limiting concentrations, did not occur when ammonia was present… more
Date: December 1991
Creator: Silva Avalos, Juan G. (Juan Guillermo)
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Key Factors Influencing Retention Rates among Historically Underrepresented Student Groups in STEM Fields

Description: 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 pl… more
Date: December 2018
Creator: Premraj, Divya
Item Type: Refine your search to only Thesis or Dissertation
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Landscape Ecological Characteristics of Habitat of the Red-cockaded Woodpecker

Description: Geographic information systems (GIS) technology was used to analyze factors influencing habitat use by an endangered species, the red-cockaded woodpecker. The study area was the western part of the Raven Ranger District of the Sam Houston National Forest, Texas. The factors considered included both structural characteristics and spatial relationships among stands of trees in the habitat.
Date: December 1993
Creator: Thomlinson, John Richard
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Lethal and Sublethal Effects of Hemoxidants, Particularly Nitrite, on Selected Aquatic Animals

Description: A research program was developed to investigate basic and applied aspects of toxicity, both lethal and sublethal, of hemoxidants, particularly nitrite, on fish, non-fish aquatic vertebrates, and crayfish. The major objectives of this research were to determine A) acute and sublethal toxicity of nitrite to selected aquatic organisms: 1. aquatic salamander larvae, Ambystoma texanum, 2. swamp crayfish, Procambarus simulans, 3. bluegill, Lepomis macrochirus, 4. bullfrog, tadpoles, Rana catesbiana, … more
Date: May 1982
Creator: Huey, David W. (David Worley)
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Partner: UNT Libraries
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Life Histories Behavior and Space Partitioning in Selected Species of Western North American Plecoptera

Description: Five species of stoneflies (Zapada haysi, Plumiperla diversa, Taenionema pacificum, Isoperla petersoni, Arcynopteryx compacta) from the North Slope and Interior of Alaska were examined for seasonal patterns of emergence of adults and growth of nymphs. Generally growth was retarded during the winter in this region, and all species except I. petersoni completed growth prior to January. The life cycles of six stonefly species (Prostoia besametsa, Triznaka signata, Sweltsa coloradensis. Isoperla fu… more
Date: August 1988
Creator: Hassage, Rodney Lynn, 1947-
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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