M.Sc. / There has been an increasing concern worldwide regarding the possible adverse effects of pharmaceutical supplements present in our aquatic ecosystems and whether or not they modify or alter physiological functioning in humans and wildlife. Trenbolone acetate (TBA) for example, is a commonly used androgenic anabolic steroid used in the production of cattle. TBA is metabolized into trenbolone-β and excreted as both trenbolone-α and -β. In liquid manure trenbolone-β has a half-life of over 270 days. Therefore if released into the surrounding environment there could be severe ecological impacts. The aim of this study was to determine the physiological effects of hormones used as growth stimulants in cattle production on the Sharptooth Catfish - Clarias gariepinus. The growth stimulants assessed in this study included; Trenbolone acetate, Methyltestosterone, Diethylstilbestrol and Zeranol. The aim was pursued with the use of three biomarker assays - Glutathione-S-transferase (GST), Uridine-Diphosphate Glucuronosyltransferase (UDPGT) and Cellular Energy Allocation (CEA). Fish were exposed under controlled conditions for a period of 5, ten and 15 days respectively using a flow-through system. Testes were removed and standard histological techniques were employed. Selected target organs were removed and immediately frozen in liquid nitrogen and stored at -80°C until needed for biomarker analysis.The results obtained from the gonado-somatic Index (GSI) showed that there were no significant differences (p<0.05). The hepato-somatic index (HSI) increased throughout all the different exposure groups. The histological assessment showed no significant alterations in the cell structure of the testes. With regards to the biomarkers used, CEA reflected changes in both the energy available and the energy consumed by the test organisms during the exposures. A common trend was observed throughout the different exposures. A change would occur after the ten day exposure period however a recovery would be made after 15 days of exposure. Both GST and UDPGT reflected increased activity in the liver with GST reflecting a significant difference (p<0.05) between the control and the exposure groups, however GST activity in the kidneys were not affected. To conclude, further studies will be needed to determine whether or not these growth stimulants will have a significant effect at higher concentrations and over longer exposure periods.

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Crossbred lambs were injected with L-arginine hydrochloride (arg) to determine the effects of single of multiple arg challenges on growth hormone (GH) secretion. Indwelling jugular catheters were inserted. At the beginning of each of 3 trials, lambs were injected with saline and blood samples were collected for 90 min to establish baseline GH. Blood sampling continued at 5-min intervals until 1 h after the final injection, then at 10-min intervals for one additional hour. In trial 1 arg (.5g/kg) was injected into 6 lambs while the other 6 received a second saline injection. Trial 2 consisted of 3 arg injections given at 1-h intervals. Trial 3 utilized 4 arg injections given at 15-min intervals. Trials 2 and 3 were replicated using a switchback design. Serum GH and insulin were measured by double antibody RIA. Mean GH for treated lambs in trial 1 was 3.89 ng/ml versus 1.74 ng/ml in controls (P<.01). GH peaked 30 min after injection (9.47 ng/ml), declined to 5-times baseline and remained near that level throughout the sampling period. Serum insulin was not different between treatments. In trial 2 arg treated lambs had higher mean GH (2.57 ng/ml) than controls (.86 ng/ml; P<.01). Peaks of GH were observed 20 min after the first injection (7.59 ng/ml) and 1 h after the second injection (5.6 ng/ml). No increase in GH was observed after the third injection. Insulin tended to follow the same pattern, but was not significantly elevated in treated lambs. Differences in trial 3 mean GH between arg-treated lambs (5.25 ng/ml) and controls (1.16 ng/ml) were significant (P<.01). GH peaked (13.8 ng/ml) at 25 min after the first injection, surged again 100 min later (7.4 ng/ml), declined to levels 3-times baseline and remained elevated. Trial 3 insulin levels were significantly higher in treated lambs (.64 ng/ml) compared to control lambs (.15 ng/ml; P<.01). Control lambs showed no significant GH or insulin increases at any time. GH secretion patterns were significantly altered in lambs injected with arg. One arg injection caused GH to peak within 30 min. Further challenges resulted in smaller, delayed rise and persistence of elevated GH levels. Insulin levels tended to increase with arg stimulus, but were not significantly elevated except at extremely high doses of arg. The data reflects a consistent relationship between arg stimulus and serum GH. / Master of Science / incomplete_metadata

Thesis (Ph.D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed on June 8, 2009). Includes bibliographical references.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: This study describes: 1. The isolation and the purification of tissue type plasminogen activator and urokinase plasminogen activator in bovine milk. 2. The biochemical characterisation of tissue type plasminogen activator in bovine milk. 3. An investigation of the influence of the addition of purified tissue type plasminogen activator to ultra high temperature milk, Gouda cheese and yoghurt. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf: 1. Die isolering en suiwering van weefseltipe-plasminogeenaktiveerder en urokinase-plasminogeenaktiveerder in beesmelk. 2. Die biochemiese karakterisering van weefseltipe-plasmingeenaktiveerder in beesmelk. 3. `n Ondersoek na die invloed van die byvoeging van gesuiwerde weefseltipe-plasminogeenaktiveerder by ultra hoë temperatuur melk, Gouda kaas en joghurt.

published_or_final_version / abstract / Zoology / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy