Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 36-40). Also available via the Internet.

Thesis (M.A.)--University of Louisville, 2004. / Department of History. Vita. "May 2004." Includes bibliographical references (leaves 84-99).

Thesis (Ph. D.)(Genetics)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Degree Not Listed / Department of Clinical Sciences / Warren L. Beard / Recumbency affects respiratory mechanics and oxygenation in anesthetized horses. Changes in pleural and abdominal pressures that can impair ventilation have not been described in all recumbencies. The objective of this study was to determine the effects of patient positioning on transdiaphragmatic pressures and selected hemodynamic variables. Horses were maintained under total intravenous general anesthesia with nasal oxygen supplementation. Trans-nasal balloon catheters connected to pressure transducers placed within the stomach and thoracic esophagus were used to measure intrathoracic and gastric pressure in standing and anesthetized horses positioned in: right and left lateral recumbency, dorsal recumbency, reverse Trendelenburg position, and Trendelenburg position. Transdiaphragmatic pressures were calculated as the difference between gastric and intrathoracic pressure. Measurements of SpO2, heart rate, systolic, diastolic and mean arterial pressure, and respiratory rate were obtained every 5 minutes. When compared to dorsal recumbency, gastric expiratory pressure is decreased in the standing position. Thoracic expiratory pressure is decreased in standing and reverse Trendelenburg. Transdiaphragmatic expiratory pressure and SpO2 are decreased in Trendelenburg. Heart rate is increased in reverse Trendelenburg. Systolic, diastolic, and mean arterial pressures are decreased in reverse Trendelenburg and increased in left lateral and right lateral. We found there is wide variation in respiratory pressures between horses and positions and they are not predictive of associated changes in hemodynamic variables.

The use of hydroponic feeding systems for horses has gained in popularity during recent years. Typically, this feeding system allows for a more efficient use of the whole plant, including the shoot, root, and seed remnants rather than traditional grazing in which only the shoot of the plant is consumed. Vertical systems have practical uses in largely developed areas where traditional forage sources are limited, in arid countries or in areas with severe droughts where forage growth is minimal. Though there is some research on fodder utilization in production animals, there are currently no published data on the effects of fodder in horses. Our study, approved by the Southern Illinois University Institutional Animal Care and Use Committee (#13-043) utilized eight Quarter Horse mares randomly assigned to one of two diets. Control (CON) horses were offered 2% of their body weight (BW) in hay (DM) and treatment (TRT) horses received 1% of their BW in hay (DM) and 1% of BW in fresh wheat fodder (AF) twice daily. Body weight and hoof temperature data were recorded weekly. Fecal samples were collected weekly and analyzed for pH, NH3, and VFA concentration as well as DM, ash, NDF, ADF, N, CP, and EE. Hay and fodder samples were also collected weekly to monitor nutrient profiles of the two forage types for the duration of the study. Additionally, nutrient profiles from seed to mature (8 d growth) were developed for fodder. Data were analyzed as a completely randomized design using PROC MIXED of SAS (v. 9.4) and significance was established at P < 0.05. There were no significant differences in body weight, left or right front hoof temperatures between treatments. Fecal pH was significantly lower (P ≤ 0.01) in the TRT when compared to CON, and isobutyric acid was significantly (P ≤ 0.05) higher in TRT as compared to CON. A comparison of the nutrient values of the two forages demonstrated significantly higher DM, ash, NDF, and ADF (P <0.0001) in hay while N, CP, and EE (P <0.0001) were significantly higher in fodder overall. Daily growth of the fodder decreased DM content (P <0.0001) while ash, NDF, ADF, N, CP, and EE (P <0.0001) increased as the fodder reached maturity. These results indicate that utilizing fodder affects fecal metabolites associated with digestion.

No description available.

No description available.

Osteoarthritis of the metacarpo/metatarsophalangeal joint is a major cause of lameness in the horse. Magnetic resonance imaging and particularly delayed gadolinium enhanced imaging of cartilage (dGEMRIC) and T2 cartilage mapping in humans has been shown to visualize cartilage matrix changes in osteoarthritis early in the disease process. T2 mapping is a non-invasive technique characterizing hyaline articular cartilage and repair tissue. In dGEMRIC, the negatively charged administered Gd-DTPA2−, penetrates hyaline cartilage in an inverse relationship to the proteoglycan concentration thereof. In osteoarthritis, proteoglycan concentration is decreased with increased penetration of Gd-DTPA2− due to a relative decrease in negative charge of the proteoglycan-depleted cartilage. This study was performed on normal cadaver limbs of twelve euthanized racing Thoroughbreds. Six horses’ midcondylar distal third metacarpals/metatarsals (Mc3s/Mt3s) underwent six precontrast inversion recovery (IR) sequences for dGEMRIC T1 relaxation time calculation, as well as T2 mapping sequences using a 1.5T machine. Gd-DTPA2- was injected intra-articularly and the same six IR sequences repeated at 30, 60, 120, and 180 minutes post-injection at the same midcondylar sites. The distal Mc3/Mt3 cartilage thickness was measured histologically and compared to selected images of the T1 and T2 weighted sequences. T1 and T2 maps were created by fitting the respective data into mono-exponential relaxation equations for each pixel, and mean values of certain regions of interest were calculated. A second group of six horses’ fore and hind limbs were randomly assigned to two groups and the limbs either chilled or frozen, allowed to return to room temperature and scanned similarly to the first control group. Chilling and freezing effects on dGEMRIC and T2 mapping results were evaluated. The main conclusions from this study are that IR and proton density weighted (T2 mapping) sequences can measure distal Mc3/Mt3 cartilage thickness where the cartilage doesn’t overlap with that of the proximal phalanx. However, accurate measurement was hampered by the thin cartilage in this region. dGEMRIC mapping, using intra-articular Gd-DTPA2- is a feasible technique and T1 relaxation times decrease in a similar fashion to that of the human, with the optimal time of scanning after intra-articular Gd-DTPA2- injection being 60-120 minutes. There is little effect on T1 or T2 relaxation time and mapping images after chilling and freezing of the limbs except where the magic angle effect predominates in the T2 mapping sequences. Limitations of this study include relatively coarse spatial resolution of the thin cartilage, the overlap of the distal Mc3/Mt3 cartilage with the adjacent phalanx and the relatively low number of limbs used, resulting in low statistical power, particularly in the frozen limbs’ study. In spite of these limitations, this study provides technical information and reference values of dGEMRIC and T2 mapping in the cadaver distal Mc3/Mt3 of the normal Thoroughbred horse of value for forthcoming studies. Future studies need to evaluate intravenous administration of Gd-DTPA2- and cartilage mapping in live exercised vs. non-exercised horses. Ultimately, dGEMRIC and T2 mapping of horse metacarpo/metatarso-phalangeal joints with differing degrees of osteoarthritis should be used to attempt to diagnose early cartilage degeneration to endeavour to halt or delay its progression. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Companion Animal Clinical Studies / unrestricted

African horse sickness virus (AHSV), a member of the Orbivirus genus within the Reoviridae family, has a 10-segment double-stranded (ds)RNA genome enclosed within a double capsid. In addition to seven structural proteins (VP1-VP7), four non-structural proteins (NS1, NS2 and NS3/NS3A) are synthesized in infected cells and are involved in virus morphogenesis. Due to the lack of a reverse genetic system for orbiviruses, analyses regarding AHSV gene function have been limited to the characterization of individual virus proteins following their expression in heterologous expression systems. The phenomenon of RNA interference (RNAi), has, however, revolutionized approaches to study the function of individual genes. RNAi is an evolutionary conserved mechanism by which RNA duplexes, known as short interfering RNA (siRNA), can reduce gene expression through enzymatic cleavage of complementary mRNA. In addition to synthetic siRNA, RNAi can also be induced in mammalian cells by plasmid and viral vector systems that express short hairpin RNAs (shRNAs) that are subsequently processed to siRNAs by the cellular machinery. Consequently, the aim of this investigation was to establish a plasmid DNA vector-based RNAi assay whereby the expression of the AHSV-9 NS2 gene could be suppressed in BHK-21 cells. Complementary oligonucleotides corresponding to selected AHSV-9 NS2 gene sequences were chemically synthesized, annealed and cloned into the pSUPER shRNA delivery vector, downstream of the RNA polymerase III H1 promoter. The vector-expressed shRNAs targeted regions within the NS2 gene corresponding to nucleotides 211 to 230 (shRNA-211), 377 to 396 (shRNA-377) and 958 to 977 (shRNA-958), respectively. To determine whether the NS2-directed shRNAs was capable of silencing NS2 protein expression, BHK-21 cells were co-transfected with the respective pSUPER shRNA delivery vectors and a NS2 reporter plasmid, pCMV-NS2-eGFP. Fluorescence microscopy indicated that NS2-eGFP expression was makerdly reduced in these cells compared to cells transfected with the reporter plasmid only, and fluorometry analysis indicated that the level of inhibition mediated by the shRNAs were in excess of 80%. The potential of the NS2-directed shRNAs to reduce the level of NS2 transcripts in AHSV-9 infected BHK-21 cells was also investigated by transfection of the BHK-21 cells with the respective pSUPER shRNA delivery vectors, followed by virus infection. Results obtained by means of semi-quantitative real-time reverse transcriptase-polymerase chain reactions indicated that shRNA-377 interfered the most efficiently with NS2 mRNA expression, and the greatest silencing effect was observed at 24 h post-infection. During the course of this investigation it was also attempted to establish a BHK-21 cell line that stably expressed the NS2-directed shRNA-377. For this purpose, a recombinant pSUPER.Retro.Puro retroviral vector was constructed and following transfection of BHK-21 cells, stable transfectants were selected by growth in the presence of puromycin. Results indicated that although the derived cell line suppressed AHSV-9 NS2 mRNA expression, the plasmid DNA was maintained extrachromosomally. Overall, the results of this investigation have provided evidence that AHSV-9 NS2 gene expression can be suppressed in mammalian cells by vector-derived shRNAs. / Dissertation (MSc)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted