The purpose of this research was to characterize the antibody-mediated inhibition of horseradish peroxidase activity. Inhibition of enzyme activity was determined when alternate substrates were used. Typical biphasic patterns of inhibition were observed with each of five electron donors and three hydroperoxides. In no case was inhibition complete (100%). Inhibition assays with varied substrate concentrations revealed a dependence of anticatalytic activity upon the hydroperoxide concentration. Increased hydroperoxide concentration elevated inhibition levels. Inhibition is not dependent upon the electron donor concentration. The dependence of inhibition levels on hydroperoxide concentration suggests that antibody may make the horseradish peroxidase basic isoenzyme more susceptible to peroxide inactivation. Kinetic data show increased enzyme affinity for hydrogen peroxide in the presence of antibody. In addition, acidic peroxidases that are less susceptible to peroxide are poorly inhibited by antibasic horseradish peroxidase. Spectrophotometric experiments with an electron donor analogue indicated that antibody does not inhibit horseradish peroxidase activity by preventing electron donor binding. Inhibitory antibody binding sites could not be determined because fragments of the enzyme capable of binding inhibitory antibody could not be produced. Antisera prepared against acidic horseradish peroxidase isoenzymes were used in immunological procedures (precipitation, anticatalytic assays) to assess the homology of horseradish, radish and turnip peroxidases. Acidic horseradish peroxidases with similar physicochemical properties are distinguishable by immunological methods. Interspecies relationships are stronger among acidic peroxidases than relationships between acidic and basic horseradish isoenzymes. These results support an evolutionary conservation of acidic isoenzymes and suggest that each isoenzyme group catalyzes specialized plant functions. / M.S.

Equine recurrent airway obstruction (RAO) is associated with airway inflammation and bronchoconstriction in clinically affected horses. Horses demonstrating severe pulmonary compromise develop concurrent secondary pulmonary hypertension. The development of pulmonary hypertension is well documented in RAO affected horses, however, it is not known how rapidly increases in pulmonary artery pressure occur after the onset of RAO. It is also not known if pulmonary hypertension resolves concurrently with resolution of RAO. The goal of this study was to measure pulmonary artery pressure in RAO affected horses during the development and resolution of RAO. To accomplish this, three RAO affected and three normal horses were placed in a challenge environment where clinical parameters, pulmonary function, right heart and pulmonary artery pressures were measured on day 1, 3 and 5. After evaluating horses on day five, their environment was modified to reduce exposure to respirable debris and anti-inflammatory medication (dexamethasone) was initiated. Identical clinical parameters were measured on days 7 and 9. In our study, the arterial oxygen content in RAO horses was significantly less that that of control horses from day 1 through day 9. A concurrent increase in pulmonary artery pressure also developed on day 3 in RAO affected horses, and persisted through day 5. While some trend towards a difference between groups was noted, no other significant differences were observed between RAO and normal horses. These findings suggest that horses with severe RAO also develop significant increase in pulmonary artery pressure, which rapidly resolves with appropriate management of RAO. / Master of Science

Corneal sensitivity and adverse events following subconjunctival administration of three local anesthetics in twelve mares were evaluated. The subconjunctival space of the treated eye was injected with 0.2 mL of mepivacaine (2%), ropivacaine (1.3%) and liposomal bupivacaine (1.3%). All horses received each medication once and the contralateral eye received saline. The corneal touch threshold (CTT) was measured using a esthesiometer before sedation, after sedation, and at specified intervals until it returned to baseline. The mean total time of anesthesia (TTA) was 168.3 minutes for ropivacaine, 169.2 minutes for liposomal bupivacaine, 103.3 minutes for mepivacaine and 30.7 minutes for control. The TTA for liposomal bupivacaine (P<0.001) and ropivacaine (P=0.001) was longer than the control. The TTA for mepivacaine was not different from the control (P = 0.138), liposomal bupivacaine (P = 0.075) or ropivacaine (P = 0.150). Injection site hemorrhage reduced TTA regardless of treatments (P=0.047). No adverse effects were noted.

Chronic, low-grade inflammation is a contributing factor in diseases that impact the health and well-being of horses. Pharmaceutical treatments reduce inflammation, but their use results in negative digestive and kidney disturbances. Polyunsaturated fatty acids (PUFA) play a role in mitigating the inflammatory response and are therefore explored as a dietary approach to attenuate inflammation. γ-Linolenic acid (GLA) is a unique PUFA that when supplemented in the diet can increase the production of anti-inflammatory eicosanoids; however, it is uncommon in the dietary components normally fed to horses. Interest in industrial hemp (Cannabis sativa L.) as a novel source of PUFA stems from the presence of GLA and the potential to reduce inflammation; although, concerns over cannabinoid contamination limit its acceptance. Six Thoroughbred geldings were used in a crossover study with two 63-d periods to measure PUFA metabolism, inflammatory biomarkers, and cannabinoid accumulation in response to hempseed oil (HSO) fed to sedentary horses compared to controls (CON). Treatment diets were offered for the first 35 d of each period and then all horses resumed a uniform feeding rate from d 36 to 63. Serum and synovial fluid PUFA reflected dietary intake. GLA was greater in serum (0.465 vs. 0.046; P < 0.0001) and synovial fluid (0.270 vs. 0; P < 0.0001) in horses fed HSO compared to CON. This contributed to greater dihomo-γ-linolenic acid (DGLA) conversion in serum (0.287 vs. 0.195; P < 0.0001) and synovial fluid (0.348 vs. 0.262; P < 0.04) but not arachidonic acid (AA). Serum GLA returned to baseline concentrations by two weeks post-supplementation, but no treatment x time effect was observed for synovial fluid. HSO did not affect FA in muscle; it is likely the length or quantity of supplementation was inadequate to see changes in muscle PUFA. HSO increased serum interleukin 1β (IL1β; P = 0.01) but there was no treatment by time interaction (P = 0.62). No other inflammatory biomarkers were influenced by treatment. Stride length was not affected by HSO supplementation but was inversely correlated (P ≤ 0.01) with synovial fluid prostaglandin E2 (PGE2; r = -0.56), and positively correlated with serum tumor necrosis factor α (TNFα; r = 0.58), serum IL6 (r = 0.61), and serum IL1β (r = 0.65). Cannabinoids were measured in the HSO supplement, but no cannabinoids were detected in plasma or synovial fluid of horses fed HSO when tested to a 50-ppb limit of detection. These results demonstrate the suitability of HSO as a novel source of PUFA and, more specifically, as a source of GLA without further increasing AA, however, implications for its effect on inflammation require further evaluation. / Doctor of Philosophy / Inflammation contributes to diseases in the horses that reduce their health and well-being. Anti-inflammatory drugs reduce inflammation but are associated with negative health effects including gastric ulcer formation and kidney damage. Diet can influence the inflammatory response and is therefore targeted to moderate inflammation. Specific dietary targets include polyunsaturated fatty acids (PUFA). Hempseed (Cannabis sativa L.) oil (HSO) contains a unique and uncommon dietary PUFA, γ-Linolenic acid (GLA), which can increase the production of anti-inflammatory biomolecules. The goal of this research was to measure PUFA accumulation, specifically GLA, in horses fed HSO for 35 d and then clearance for 28 d post-supplementation. Additionally, we looked at inflammatory markers to determine the effect on inflammation in sedentary horses. Finally, we measured cannabinoids to evaluate if the low level of cannabinoid contamination found in HSO transfers to horse plasma and synovial fluid. To accomplish these goals, we conducted a feeding trial from May 2022 to September 2022 using six Thoroughbred geldings in a cross over study with two 63 d periods. HSO was supplemented the first 35 d of each period and then removed. Serum and synovial fluid PUFA reflected dietary PUFA. Inflammatory biomarkers had a mixed response that could be influenced by additional, unknown factors. The low-level of cannabinoids in the HSO supplement were not detected in plasma or synovial fluid. HSO shows promise as a novel source of PUFA, specifically GLA, without concerns of cannabinoid contaminants.

The objective of this study is to determine if fat as an energy source, and fiber in a pasture supplement will be beneficial when compared to a concentrate high in sugar and starch. In the first experiment, 12 pregnant and lactating mares were used in three different glycemic response tests to determine the effect of feeds on pregnant mares. The mares were fed a pelleted concentrate (PC) three months before foaling; after foaling they were divided into two groups and fed a feed high in sugar and starch (SS), or a feed high in fat and fiber (FF). The second experiment, used the same 12 mares (R mares) and 10 barren mares (B mares) in three different tests to determine the effects of the feeds, season and reproductive stage. A series of blood samples was collected via a jugular catheter from 0 to 390 min after consuming a meal. Glucose and insulin baseline and peak values, increments and areas under curves (AUC) were compared by ANOVA. For the first experiment, responses to PC did not differ between the two groups. Peak plasma glucose and insulin concentrations were higher in SS group than in FF during both early and late lactation. Glucose and insulin AUCs were higher in SS than in FF during both early and late lactation. In the second experiment, peak glucose increments had differences for the main effects feed, pregnancy and season, and interactions feed by pregnancy and feed by season. The glucose AUC values showed similar differences for the main effects and the interaction feed by pregnancy. Peak insulin increments had a difference for feed and pregnancy, but not the interactions. Insulin AUCs also revealed a difference between feed and pregnancy, and also for season, and the interaction feed by pregnancy. These results indicate that metabolic fluctuations are moderated by the replacement of sugar and starch with fat and fiber. This replacement may reduce the risk of certain digestive and metabolic disorders. / Master of Science

This study determined whether an association exists between the perception of western wear status symbols and demographic characteristics {i.e., gender, age, income, and education level) among Texas American Paint Horse Association members.

African horse sickness virus (AHSV) is a ten-segmented, dsRNA virus, classified as a distinct species within the genus Orbivirus, family Reoviridae. There are nine serotypes of AHSV, any of which can cause African horse sickness (AHS), an extremely severe ‘transboundary’ and notifiable disease of horses, listed by OIE. AHS is currently restricted to sub-Saharan Africa, but has occasionally emerged causing major outbreaks in other geographic regions. Complete genome nucleotide sequences were determined for nine reference-strains of AHSV (different serotypes). The selection-pressure on each genome-segment and its encoded proteins, in relation to protein function were analysed in phylogenetic comparisons. This initial AHSV sequence database also provided a basis for molecular-epidemiology studies. In particular, the role of the Seg-2 in determination of virus-serotype was used to identify viruses involved in a multi-serotype outbreak, identifying Ethiopia as an important area of AHSV circulation. Phylogenetic-relationships were also investigated between different isolates of AHSV serotypes 2, 4, 6, 8 and 9, from various locations in Africa. Two real-time RT-PCR assays were developed for detection of the highly conserved genome segments 1 and 3, and molecular diagnosis of AHSV. Real-time RT-PCR assays were also developed, targeting Seg-2, for detection and identification of the nine AHSV serotypes. These assays are suitable for ‘high throughput’ characterisation of AHSV outbreak-strains, from either endemic or AHSV-free zones. The results obtained would facilitate rapid design and implementation of appropriate virus control measures. Cross-contamination was detected in four of the original AHSV reference-strains. A new set of plaque-cloned and monotypic reference-strains was therefore identified and characterised, and is available through the Orbivirus Reference Collection (http://www.reoviridae.org/dsRNA_virus_proteins/ReoID/AHSV-Nos.htm). Serological relationships were analysed using antibodies against VP2 of AHSV-9 (expressed by recombinant MVA) and the nine monotypic reference-strains, showing neutralisation of both AHSV-9 and AHSV-6, in agreement with their closer phylogenetic relationship within Seg-2/VP2.

Cheung Man-Yuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 35-40). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rank Regression --- p.1 / Chapter 1.2 --- Clustering --- p.2 / Chapter 1.3 --- Modeling of the ranked data --- p.3 / Chapter 1.4 --- Application in Horse Racing data --- p.4 / Chapter 2 --- Semi-Parametric Regression Model --- p.7 / Chapter 2.1 --- Review --- p.7 / Chapter 2.2 --- Parameter Estimation --- p.9 / Chapter 3 --- Random Effects --- p.11 / Chapter 3.1 --- Definition --- p.11 / Chapter 3.1.1 --- A Simple Estimation Algorithm --- p.13 / Chapter 3.2 --- Metropolis-Hastings Algorithm for Simulating Random Effects --- p.14 / Chapter 3.3 --- EM Algorithms for Maximizing the Likelihood --- p.16 / Chapter 3.3.1 --- Stochastic EM Algorithm --- p.17 / Chapter 3.3.2 --- MCEM Algorithm --- p.18 / Chapter 4 --- Application --- p.20 / Chapter 4.1 --- Fundamental Variables and Variable Selection --- p.21 / Chapter 4.2 --- Simulation Results --- p.23 / Chapter 4.3 --- Betting Strategies and Comparisons --- p.25 / Chapter 5 --- Conclusions and Further Studies --- p.29 / Appendix --- p.31 / Bibliograply --- p.35

Siu, Man Tat. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 51-54). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii-iii / Table of Contents --- p.iv / Chapter Chapter 1 --- Introduction --- p.1-10 / Chapter Chapter 2 --- Literature Review --- p.11-13 / Chapter Chapter 3 --- Data --- p.14-20 / Chapter Chapter 4 --- Model --- p.21-30 / Chapter Chapter 5 --- Empirical Result --- p.31-43 / Chapter Chapter 6 --- Discussion and Conclusion --- p.44-50 / References --- p.51-54 / Figures and Appendix --- p.55-66

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