The pharmacokinetics, oral bioavailability, cerebrovascular permeability and biotransformation of the neurotoxic plasticiser n-butylbenzenesulfonamide (NBBS) were studied in order that the human health risk due to environmental exposure to NBBS could be evaluated. The pharmacokinetics of NBBS was determined in Wistar rats, following intravenous administration of the isotopomer [13C6] NBBS (1 mg/kg in 0.9% saline). [13C6] NBBS is cleared from plasma at a rate of 5 ml/min by the liver. The plasticiser has a short distribution phase (t1/2 of 47 seconds) and a long terminal phase (t1/2 of 17 hours). Plasma [13C6] NBBS concentrations, 24 hours after administration, represented 0.04% of the administered dose. These data indicated rapid uptake into tissue, which was subsequently confirmed by monitoring tissue concentrations of [13C6] NBBS for upto 8 hours following administration. [13C6] NBBS was not accumulated by any of the tissues studied (brain, liver, kidney, muscle and adipose tissue). Oral bioavailability was determined by simultaneously administering native NBBS orally and [13C6] NBBS intravenously to Wistar rats. The plasticiser was found to be absorbed erratically and subject to first pass metabolism. Plasma concentrations of orally administered NBBS fluctuated over the duration of the experiment. Furthermore, limitations posed by the assay resulted in truncated oral curves. These factors precluded estimation of areas under the oral NBBS curves to infinity and partial area ratios were instead used to calculate absolute bioavailability (mean of 19%). Cerebrovascular permeability of NBBS was determined with [13C6] NBBS, in Sprague-Dawley rats, using the in-situ brain perfusion technique of Takasato et al. (1984). The uptake of [13C6] NBBS into brain was very rapid and flow limited. Assuming an average cerebral perfusion fluid flow rate of 0.11 ml/s/g, the calculated single pass extraction value for [13C6] NBBS is 99.9% with a Kin of 0.11 ml/s/g. This is in close agreement with experimental values for the 15 second saline perfusions (extraction = 98% - 125% and Kin = 0.108 - 0.137). Differences in regional brain distribution of the plasticiser were not found. In-vitro biotransformation studies revealed one phase I metabolite in incubates of NBBS containing human, rabbit and rat post-mitochondrial supernatant (S9 fraction). This metabolite is 2-hydroxy-n-butylbenzenesulfonamide (NBBS-OH hydroxylated in the Based on these data, environmental exposure to NBBS does not pose a significant human health risk.

8-Cyclopentyl-3-(3-(4-fluorosulfonylbenzoyl)oxy)propyl-propylxanthine (44, FSCPX) has been reported to exhibit potent and selective irreversible antagonism of the A1 adenosine receptor when using in vitro biological preparations. However, FSCPX (44) suffers from cleavage of the ester linkage separating the reactive 4-(fluorosulfonyl)phenyl moiety from the xanthine pharmacophore when used in in vivo biological preparations or preparations containing significant enzyme activity, presumably by esterases. Cleavage of the ester linkage renders FSCPX (44) inactive in terms of irreversible receptor binding. In order to obtain an irreversible A1 adenosine receptor antagonist with improved stability, and to further elucidate the effects of linker structure on pharmacological characteristics, several FSCPX (44) analogues incorporating the chemoreactive 4-(fluorosulfonyl)phenyl moiety were targeted, where the labile ester linkage has been replaced by more stable functionalites. In particular, ether, alkyl, amide and ketone linkers were targeted, where the length of the alkyl chain was varied from between one to five atoms. Synthesis of the target compounds was achieved via direct attachment of the N-3 substituent to the xanthine. These compounds were then tested for their biological activity at the A1 adenosine receptor via their ability to irreversibly antagonise the binding of [3H]-8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX, ( 9) to the A1 adenosine receptor of DDT1 MF-2 cells. For comparison, the xanthines were also tested for their ability to inhibit the binding of [3H]-4-(2-[7-amino-2-{furyl} {1,2,4}- triazolo{2,3-a} {1,3,5}triazin-5-ylamino-ethyl)]phenol ([3H]ZM241385, 36) to the A2A adenosine receptor of PC-12 cells. The results suggest that the length and chemical composition of the linker separating the reactive 4-(fluorosulfonyl)phenyl moiety from the xanthine ring contribute to the potency and efficacy of the irreversible A1 adenosine receptor ligands. Like FSCPX (44, IC50 A1 = 11.8 nM), all derivatives possessed IC50 values in the low nM range under in vitro conditions. Compounds 94 (IC50 A1 = 165 nM), 95 (IC50 A1 = 112 nM) and 96 (IC50 A1 = 101 nM) possessing one, three and five methylene spacers within the linkage respectively, exhibited potent and selective binding to the A1 adenosine receptor versus the A2A adenosine receptor. Compound 94 did not exhibit any irreversible binding at A1 adenosine receptors, while 95 and 96 exhibit only weak irreversible binding at A1 adenosine receptors. Those compounds containing a benzylic carbonyl separating the 4-(fluorosulfonyl)phenyl moiety from the xanthine ring in the form of an amide (119, IC50 A1 = 24.9 nM, and 120, IC50 A1 = 21 nM) or ketone (151, IC50 A1 = 14 nM) proved to be the most potent, with compound 120 exhibiting the highest selectivity of 132-fold for the A receptor over the A2A receptor. compounds 119, 120 and 151 also strongly inhibited the binding of [3H]DPCPX irreversibly (82%, 83% and 78% loss of [3H]DPCPX binding at 100 nM respectively). compounds 120 and 151 are currently being evaluated for use in in vivo studies. Structure-activity studies suggest that altering the 8-cycloalkyl group of A1 selective xanthines for a 3-substituted or 2,3-disubstituted styryl, combined with N-7 methyl substitution will produce a compound with high affinity and selectivity for the A2A adenosine receptor over the A1 adenosine receptor. Compound 167 (IC50 A2A = 264 nM) possessing 8-(m-chloro)styryl substitution and the reactive 4-(fluorosulfonyl)phenyl moiety separated from the xanthine ring via an amide linker in the 3-position (as for 119 and 120), exhibited relatively potent binding to the A2A adenosine receptor of PC-12 cells, with a 16-fold selectivity for that receptor over the A1 adenosine receptor. However, compound 167 exhibited only very weak irreversible binding at A2A adenosine receptors. Overall, at this stage of biological testing, compound 120 appears to possess the most advantageous characteristics as an irreversible antagonist for the A1 adenosine receptor. This can be attributed to its high selectivity for the A1 adenosine receptor as compared to the A2A adenosine receptor. It also has relatively high potency for the A1 adenosine receptor, a concentration-dependent and selective inactivation of A1 adenosine receptors, and unbound ligand is easily removed (washed out) from biological membranes. These characteristics mean compound 151 has the potential to be a useful tool for the further study of the structure and function of the A1 adenosine receptor.

The suppressor of cytokine signaling ( SOCS ) proteins have been identified as important regulators of cytokine signaling. SOCS - 3 has been identified as being essential for normal fetal growth and survival, with the null mutation of the socs - 3 gene resulting in embryo death. The specific role of SOCS - 3 in fetal development, however, has yet to be characterized. Therefore, the overall aim of this thesis was to identify and quantify SOCS - 3 mRNA in a range of fetal tissues in the sheep. After identification of SOCS - 3 expression in fetal tissues, we then aimed to determine the ontogenic profile of SOCS - 3 in three key fetal tissues ; the liver, adipose tissue and adrenal gland, and whether SOCS - 3 expression in these tissues was altered after withdrawal and stimulation of prolactin ( PRL ). SOCS - 3 mRNA was found to be differentially expressed in a range of fetal tissues in late gestation and was higher in the fetal liver than in the pancreas, spleen and kidney. SOCS - 3 expression increased throughout gestation in the fetal liver, however, its expression decreased in the fetal adipose tissue and adrenal in late gestation. The pituitary hormone PRL has previously been implicated as a fetal growth factor. In the sheep fetus, PRL receptors are expressed in the fetal liver, adipose tissue and adrenal. We aimed to determine whether PRL plays a role in the maintenance of SOCS - 3 expression in the liver, adipose tissue and adrenal gland in late gestation, and whether SOCS - 3 expression can be regulated by acute PRL stimulation. We have demonstrated that PRL withdrawal suppressed SOCS - 3 expression in the liver, whereas acute PRL stimulation upregulated SOCS - 3 expression in the adrenal. Neither PRL withdrawal nor stimulation had an effect on SOCS - 3 expression in the adipose tissue. In summary, the data presented in this thesis would suggest that SOCS - 3 has tissue specific functions in late gestation. Furthermore, its expression is regulated in a tissue specific manner in response to the withdrawal or acute stimulation by PRL This provides the first evidence to suggest that the fetal liver and adrenal are both sensitive to either chronic or acute changes in plasma PRL concentrations, measured as the suppression or upregulation of SOCS - 3. We speculate that changes in SOCS - 3 mRNA expression relates to the regulation of growth and functional maturation of fetal tissues throughout gestation, and that PRL may represent an important factor which acts to alter SOCS - 3 expression in key fetal tissues. / Thesis (Ph.D.)--School of Molecular and Biomedical Science, 2006.

Bibliography: leaves x-xxii / xvii, 285, xxii leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, 1987

Includes bibliographical references (leaves 281-328) / iii, 328 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The experiments reported are investigations of the pituitary of rats stunted by undernutrition imposed between birth and 3 weeks of age. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Physiology, 1971

Includes bibliographical references (leaves 178-194). / xix, 194 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Genetic and non-genetic factors affecting fat colour in cattle were examined in biopsy and carcass samples of Jersey and Limousin cattle in their F1 and backcross progeny. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 2001

"November, 2003" / Includes bibliographical references (leaves 240-264) / xix, 264 : ill. (some col.), plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004

Includes bibliographical references (leaves 281-328) The experiments reported are investigations of the pituitary of rats stunted by undernutrition imposed between birth and 3 weeks of age.

Graduation date: 2002

The goal of this dissertation is to investigate the interaction between cimetidine and dietary flavonoids using the Caco-2 cell transport model. It has been shown that flavonoids can change the bioavailability of pharmaceuticals, either by inhibiting metabolizing enzymes or inhibiting the drug efflux transporters. However, the effect of dietary flavonoids in the absorption of cimetidine has not been investigated. Therefore, the hypothesis of this study is that the absorption of cimetidine is mediated by a drug efflux pump, P-glycoprotein, of which dietary flavonoids can enhance the permeability of cimetidine by reducing P-glycoprotein function. The increase in permeability of cimetidine can increase the bioavailability of cimetidine. To test the hypothesis, three objectives were proposed. The first objective was to validate the Caco-2 transport model in our laboratory. The validation was performed by measuring the electrical resistance ofthe monolayer and determining the transport of paracellular marker. Also P-glycoprotein function was determined using rhodamine 123. The second objective was to describe the transport characteristics of cimetidine in the Caco-2 cell monolayers. The permeability of cimetidine was determined at different pH environments. When the permeability of cimetidine from apical to basolateral and basolateral to apical was compared, there appeared to be an effiux mechanism involved transport of cimetidine. The permeability of cimetidine in the presence of verapamil, a P-glycoprotein competitive inhibitor, suggested that P-glycoprotein was involved in the effiux. The third objective was to study the effect of dietary flavonoids on the permeability of cimetidine in the Caco-2 cell model. In the present study, four different flavonoids, quercetin, genistein, naringenin, and xanthohumol were selected. When co-treated with flavonoid aglycones, the permeability ofcimetidine was significantly reduced in the basolateral to apical direction. However, only genistin, a glycoside of genistein, significantly reduced the efflux of cimetidine. The present studies demonstrate that some dietary flavonoids, especially aglycones, can significantly reduce the effiux of cimetidine in the Caco-2 cell monolayers. Therefore, the fiavonoids consumed in a normal diet have the potential to enhance the bioavailability of cimetidine and possibly other P-glycoprotein substrates by altering their permeability. / Graduation date: 2004