In Leishmania glycosomes compartmentalize a variety of essential biochemical and metabolic pathways required for parasite viability. Biogenesis and maintenance of glycosomes involves a family of proteins called peroxins, however the molecular mechanisms governing the early events of this pathway have not been fully established. / A structural-functional analysis of the receptor LdPEX5 revealed the formation of a tetrameric structure stabilized by coiled-coil motifs. A biophysical approach showed that the tetrameric structure of LdPEX5 dissociates to dimers upon binding to the PTS1 ligand. However, the tetrameric LdPEX5 is more thermodynamically favorable to bind. Lastly, LdPEX14 modulates the LdPEX5-PTS1 interaction as the presence of LdPEX14 decreases the Kd of LdPEX5-PTS1 by ∼10 folds. / PTS1-loaded LdPEX5 docks onto the glycosomal membrane via the membrane-associated LdPEX14, an interaction that was characterized by molecular mapping and biophysical approaches. In higher eukaryotes this PEX5-PEX14 interaction involves conserved WXXXF/Y pentapeptide motifs found on PEX5 and a signature sequence found on PEX14. These three repeats in LdPEX5 do not appear to be crucial for interaction with LdPEX14 thus suggesting a unique molecular mechanism mediating the docking event. On the other hand, the conserved signature motif is crucial for interaction with LdPEX5. / The topology and nature of the interaction of LdPEX14 with the glycosomal membrane is not clear. In vivo expression of FLAG-LdPEX14-HA together with proteinase digestion confirmed that both N- and C-termini are cytosolic facing. Mapping analysis revealed that the first 63 N-terminal residues of LdPEX14 are critical for anchoring LdPEX14 to the glycosomal membrane. Interestingly, expression of the first 74 amino acids of LdPEX14 is toxic to the parasites. / Finally, the structure of LdPEX14 on the glycosomal membrane was addressed by molecular mapping and biophysical techniques. Partial trypsin digestion of recombinant LdPEX14 and molecular mapping suggested that the first 250 residues of LdPEX14 were involved in the formation of the complex. Biophysical approaches and cross-linking assays suggest that this complex may consist of ∼12-100 LdPEX14 subunits. Interestingly, the structure of LdPEX14 appears to be modulated by LdPEX5. / Considering all the results, these findings have established important molecular information concerning early events in the targeting and import of PTS1 proteins into the glycosome.

Proteinase P-II purified from parasitized Pacific whiting muscle was previously identified to be one form of cathepsin L. It appeared to be present in three isozymatic forms on non-denaturing PAGE gel stained for activity. Its autolytic degradation was observed on SDS-PAGE gel under its optimum condition, 55°C and pH 5.5, in the absence of substrate. Amino acid composition analysis revealed that this enzyme had a considerably greater proportion of hydrophobic amino acids than cathepsin L from other fish species, and monosaccharide analysis showed it was not glycosylated. The N-terminal amino acid sequence of the enzyme was 60-65% identical with cathepsin L from chicken and mammalian species, but only 39% identical with mammalian cathepsin B. The moderate identity of the N-terminal amino acid sequence of P-II with other cathepsin L revealed that this cysteine proteinase from Pacific whiting might be encoded by a cathepsin L-related gene. Two degenerate primers were designed to clone cathepsins cDNA from rainbow trout. The 500-bp PCR product from rainbow trout liver cDNA contained at least three different cysteine proteinase sequences, referred to as SFL2, SFL5, and SFL17. SFL5 was the partial cDNA of trout cathepsin L, which was over 80% identical with chicken cathepsin L amino acid sequence. SFL5 was labeled with Dig-11-dUTP and used to screen a trout liver cDNA library. One positive clone referred to as LC was identified and contained a 700-bp insertion overlapping with SFL5. By combining the two overlapping sequences, a 895-bp cDNA sequence was identified, which included 88% of the mature enzyme and a 307-bp 3' end untranslated part. Its deduced amino acid sequences had 83% identity, 91% similarity with chicken cathepsin L and 73% identity, 86% similarity with human cathepsin L. SFL2 might be the partial cDNA of a novel cathepsin L-related cysteine proteinase. SFL17 may be the partial cDNA of trout cathepsin K. It had 70% identity and 89% similarity with rabbit and human cathepsin K at the amino acid level. / Graduation date: 1996

Abdominal Aortic Aneurysms (AAA) are amongst the top ten most common cause of death in those over 55 years of age. The disease is usually asymptomatic, often being diagnosed incidentally. Once diagnosed, elective repair of an AAA results in excellent long-term survival with a 3-5% operative mortality. However, up to one half of patients present with ruptured aneurysms, a complication that carries an 80% mortality in the community, and of those reaching hospital, a 50% mortality. Clearly early diagnosis and treatment results in improved survival. Screening for AAA, with ultrasound, would detect aneurysms early, prior to rupture. However, debate continues over the cost effectiveness of population based screening programmes. The identification of a sub-population at a higher risk of developing AAA would increase the yield of a screening prograrmne. A number of populations have been examined, none of which have received international acceptance. About 20% of patients with an AAA have a family history of an aneurysm. The disease is also considered to be a disease of Caucasians, both facts suggesting a strong genetic component to the disease. Perhaps a genetically identified sub-population at a high risk of developing an AAA would prove to be an ideal population for screening. This thesis examines the incidence of aneurysms and the family histories of patients with AAA in the Otago region of New Zealand. Almost twenty percent of the population has a family history of AAA. DNA was collected from each of these patients for genetic analysis. The population was divided into familial AAA and non-familial AAA for the purpose of genetic analysis and compared to a control population. AAA is believed to be a disease of Caucasians; a non-Caucasian population with a low incidence of AAA may prove to be a good control population for genetic studies. A literature review demonstrated a higher incidence of AAA in Caucasians than other ethnic groups and within Caucasians a higher incidence in patients of Northern European origin. The incidence was low in Asian communities, even in studies involving of migrant Asian populations. The New Zealand Maori are believed to have originated from South East Asia, therefore could be expected to have a low incidence of AAA and would make an ideal control population for genetic studies. A pilot study was undertaken to examine the incidence of AAA in the New Zealand Maori. The age standardised incidence of AAA proved to be at least equal in Maori to non-Maori, with a more aggressive form of the disease in Maori, manifesting with a younger age at presentation and a higher incidence of ruptured aneurysms at diagnosis. It is well known that at the time of surgery, an AAA is at the end stage in its life. At this time, inflammation and matrix metalloproteinases (MMP) enzymes are prevalent within the aneurysm wall and have destroyed the wall of the aorta. One of the most important genetic pathways regulating these enzymes is the plasminogen activator inhibiter 1-Tissue plasminogen activator-plasmin pathway. Genetic analysis of this pathway demonstrated an association of the 4G5G polymorphism in the promoter of the PAl-1 gene with familial AAA. In this insertion:deletion polymorphism, the 5G variant binds an activator and repressor, resulting in reduced PAI-1 expression and ultimately increased MMP activation. This allele was associated with familial aneurysms, 47% versus 62% non-familial AAA and 61% controls (p=0.024). A polymorphism within the tissue plasminogen activator gene was also examined and no association was found with AAA. Another way the MMPs expression could be increased is from mutations or polymorphisms in their own genetic structure. Stromelysin 3 is itself a MMP capable of destroying the aortic wall and it has a role in activating other MMPs. A 5A6A insertion:deletion polymorphism exists in the promoter of this gene. The 5A allele variant results in increased stromelysin expression and is associated with AAA 46% versus 33% in controls p=0. 0006. The actions of the MMPs are themselves inhibited by the tissue inhibitors of matrix metalloproteinases. The TIMP genes have been sequenced; two polymorphisms have been identified in the non-coding promoter area of the TIMP 1 gene. Further studies are necessary to examine the effect of these polymorphisms. Inflammation has been implicated in aneurysm progression. One of the roles of the inflammatory cells found in an aneurysm is to deliver the MMP�s to the AAA. The HLA system is integral in controlling this inflammation and was therefore examined. From this series of studies it is concluded that there is a genetic component to AAA. This thesis presents the first genetic polymorphism associated with familial AAA and explores the role of a genetic pathway in the formation of AAA.

The aim of the experiments reported in the present work was: first, to generate a rat model of lithium-induced nephrogenic diabetes insipidus (NDI), and, second, to use this to test the hypothesis that the effects of lithium were far more reaching than merely the inhibition of vasopressin induced translocation and synthesis of the water channel protein AQP2. Specifically, the effect of lithium on the abundance and distribution of the other water channel proteins, AQP1, AQP3 and AQP4 was investigated. It was found that AQP3 protein abundance was significantly reduced in the renal medulla while AQP4 was not affected. In addition, it was further hypothesized that, given the known effects of lithium on the urea transporter UT-A1 and on sodium channels and transporters, the renal medullary osmotic gradient would be dissipated by lithium. This was examined indirectly by determining the amounts of organic osmolytes in the renal medulla of rats with lithium-induced NDI. Myo-inositol was found to be 85 � 9 mmol kg⁻1 protein in the NDI rats, a reduction of 38% compared with control values, sotbitol fell from 35� 9 mmol kg⁻� in the control rats to 2.5 � 0.5 mmol kg⁻�, and glycerophosphorylcholine levels in the experimental animals were 91 � 18 mmol kg⁻� protein compared with 372 � 72 mmol kg⁻� in the controls. In addition, betaine decreased to 38 � 2 mmol kg⁻� protein from 69 � 10 mmol kg⁻� protein in the control. The urea content of the medulla was found to have fallen from 2868 � 558 mmol kg⁻� protein to 480 � 105 mmol kg⁻� protein. These data indicated that indeed the medullary osmotic gradient, the driving force for AVP-dependent fluid reabsorption in the kidney was greatly reduced during lithium-induced NDI. Thirdly, it was proposed that the sodium-channel blocker, amiloride, by acting to prevent lithium entry into the cells of the collecting duct, should ameliorate or abolish the adverse effects of lithium on the kidney. Treatment of rats with established NDI, with amiloride, reversed to a large extent the reduction in aquaporin protein expression and re-established the medullary osmotic gradient, as assessed by the ability of treated rats to concentrate their urine, and by the rise in amounts of medullary osmolytes. Administration of 0.5 mmol l⁻� amiloride to lithium-treated rats led to medullary AQP2 and AQP3 protein abundance increasing by 82% � 16% and 110% � 4% of the control level respectively. The content of urea in the medulla also increased to 2474 � 557 mmol kg⁻� protein. Finally, since in humans it is known that the chronic effect of lithium on the kidney is to cause cortical fibrosis and renal failure, microarray studies were commenced to look for evidence of early changes in gene activity in response to lithium-administration. The results showed that 77 genes were either up- or down-regulated, in particular, genes that are involved in the apoptosis pathway. In the light of these results it is plausible to suggest that the acute renal effects of lithium to induce NDI can be effectively mitigated, and reversed, by administration of amiloride. Whether this can serve to offset the chronic effects of lithium on the kidney awaits further investigation.

The autoimmune diseases embody a diverse range of common human conditions that are caused by a loss of self-tolerance in the host immune system to a specific organ or tissue type. Approximately 5% of the general population are affected by autoimmune diseases which include type 1 diabetes (T1D), rheumatoid arthritis (RA) and Graves disease (GD). The majority of the autoimmune diseases are multifactorial in origin, brought about by a combination of both environmental and genetic factors. Numerous susceptibility loci have been identified for each autoimmune disease and a number of these loci have been shown to be shared amongst the autoimmune diseases. The fine-mapping of susceptibility loci to the underlying disease genes remains the current challenge facing complex disease genetics. This project aimed to further characterise the autoimmune disease susceptibility locus IDDM6 on chromosome 18q12-21. This was achieved by using a comparative mapping approach that incorporates the study of genetic association in human autoimmune disease alongside the consomic mapping of the orthologous region in the non-obese diabetic (NOD) mouse model of autoimmunity. Deleted in colorectal carcinomas (DCC) provided a strong candidate gene at IDDM6 and the resident R201G polymorphism was identified as a functional candidate A potential mechanism for the R201G polymorphism involvement in T1D aetiology was identified where the polymorphism may affect the ability of DCC to induce apoptosis in vitro. However, no evidence for R201G association could be detected in autoimmune disease case-control datasets from the New Zealand (NZ) population (T1D n = 428, RA n = 730, autoimmune thyroid disease n = 192 (AITD); versus n = 1246 healthy controls). In addition, no evidence for R201G involvement in T1D could be provided in a transmission disequilibrium test (TDT) incorporating 382 affected sib-pair families (54.2% transmission; P = 0.15). Significant association of R201G with GD was detected in a United Kingdom (UK) dataset (P = 0.002) from the Newcastle population (423 cases vs. 393 controls) but this was not replicated in an additional dataset from the UK Birmingham population (731 cases vs 668 controls; P = 0.81). It was concluded that the R201G polymorphism may encode susceptibility to GD but is unlikely to be the sole aetiological variant that accounts for the linkage previously observed at IDDM6 in autoimmune disease. To further investigate DCC as a positional candidate at IDDM6, five SNPs were selected from a 100 kb window surrounding a DCC-resident microsatellite that had previously been associated with T1D, called "88,21". The five SNPs were genotyped in the NZ T1D dataset, and the ascertainment of estimated haplotypes in this dataset revealed association of a rare haplotype with T1D, called haplotype H (3.31% cases vs 1.17% controls; P = 0.0044), in addition to global association of all haplotypes (P = 0.018). Haplotype H was also associated in an independent case-control dataset from the UK comprised of 400 T1D subjects and 443 healthy controls (P = 0.038). Maximum support for association of haplotype H was extended when both the UK and NZ T1D datasets were combined (P = 0.0017). Association of haplotype H could not be verified in a family-based test for association using the 382 UK T1D families (P = 0.40). However, the inclusion of the DCC SNPs in a TDT analysis of the published DCC-resident microsatellites "88,21" and "55,26", that had been used to identify IDDM6, extends support for the previously-associated 2-10 haplotype (2-10 refers to the published allele nomenclature at "88,21" and "55,26" respectively; 2-10-haplotype A; 59.6% T; P = 0.0058). There was no evidence for association of the five SNPs with RA or AITD when using either individual SNP analyses or estimated haplotypes in the NZ datasets. A similar lack of association was reported for the UK Newcastle GD dataset. Taken together, these data further support DCC, or a nearby gene, as conferring susceptibility to T1D. The human genetic data that supports IDDM6 involvement in autoimmune disease is further strengthened by consomic mapping of the orthologous region in mouse, using the non-obese diabetic mouse (NOD) model of autoimmune disease. In this thesis, the first evidence for a diabetes and thyroiditis susceptibility locus on mouse chromosome 18 is presented, which have been designated Idd21 and Sat1 respectively. This was achieved by using a chromosome-replacement strain with chromosome 18 derived from the diabetes-resistant Biozzi ABH strain on a diabetes-susceptible NOD genome, called NOD.ABH[Chr�⁸]. Mouse chromosome 18 contains orthology to both IDDM6 and the rat diabetes-susceptibility locus Iddm3. The NOD.ABH[Chr�⁸] mice showed a dramatic and significant reduction in diabetes incidence (30% of females were affected by 7 months of age versus 85% in NOD; P <0.0001) and that of thyroiditis (15.5% at 12 months compared to 37.4% in NOD; P <0.002). The comparative mapping of the chromosome 18 autoimmune susceptibility locus IDDM6 in human and mouse presented in this thesis provides further support for this locus. This research also clearly defines the next steps required to fine-map IDDM6 to the underlying disease genes, especially in regard to the DCC gene.

The pressure-tension hypothesis is the governing dogma of orthodontic tooth movement. This theory proposes that the application of loads to the crown of a tooth during orthodontic mechano-therapy results in differential site-specific reactionary strains in the para-dental tissues. Briefly, following the application of orthodontic load the bone and periodontal ligament (PDL) on one side of the tooth is placed in compression favoring bone resorption, while on the other side of the tooth they are placed in tension favoring osteogenesis The present in vitro model provides a surrogate for the PDL on the tension side of the tooth during orthodontic tooth movement and aims to identify mechanically induced changes in the expression of osteo-regulatory cytokines in human PDL cell cultures in response to tensile mechanical strain. Materials and Methods: PDL explants were obtained from pathology free bicuspids of two human subjects following extraction of the teeth for orthodontic purposes. Following serial passage, cells were plated on Uniflex� plates and consigned to either the experimental or control groups. Experimental cells were exposed to a cyclic uniaxial tensile mechanical strain for 6,12 or 24 hours using the Flexercell FX 4000 strain unit. Total RNA was extracted using a two-step procedure and samples were analysed using real-time RT-PCR assays for a range of osteo-regulatory cytokines. Results: Human PDL cells expressed mRNA for a range of cytokines of known significance to osteogenesis and osteoclastogenesis in response to mechanical stimulation. Conclusions: The production of osteo-regulatory cytokines by PDL cells in response to mechanical strain suggests that these cells have the potential to contribute to the osseous modeling of orthodontic tooth movement. The presence of osteogenic signalling drive in response to tensile strain tends to support the basic assertions of the pressure-tension hypothesis.

This thesis explored whether individual differences in taste perception (as measured by the rated intensity of 6-n-propylthiouracil (PROP)) were associated with tobacco use, alcohol use and misuse and obesity in the Dunedin Multidisciplinary Health and Development Study birth cohort at age 32. This cohort of 1037 participants was assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26 and, most recently, at 32 years, when 96% of the living study members were interviewed. At age 32, participants rated the intensity of a 0.0032mol/L solution of PROP using the general labelled magnitude scale (gLMS). PROP is almost tasteless to some but tastes bitter to others. As bitter tastes are aversive, due to their association with toxicity, it has been suggested that responses to PROP may reflect individual differences in taste perception that, in turn, have a protective effect on health. Study One sought to establish correlates of rated PROP intensity in this sample. A model controlling for sex, childhood socio-economic status (SES), childhood IQ and gLMS use predicted approximately 12% of the variability in PROP ratings. This finding highlighted the importance of using appropriate covariates in research attempting to link PROP perception with health risk behaviours, as these factors have also been associated with tobacco use, alcohol use and adiposity. Study Two did not find that greater perceived intensity from PROP was protective against smoking, as pack years smoked was not associated with PROP rating and ratings between groups of smokers were not significantly different. Differences in PROP perception were not protective against the lifetime smoking in this sample. Similarly, Study Three found no evidence to suggest that greater intensity from PROP was associated with reduced alcohol misuse. Furthermore, the previously observed association between PROP and yearly alcohol consumption may be better explained by the fact that SES accounts for some of the variance in both measures. In Study Four, rated PROP intensity was associated with Body Mass Index (BMI), waist circumference and body fat percentage, in women, but not in men. These associations were weakened after the inclusion of covariates in the models, but remained significant for both BMI and body fat percentage. Findings from Study Four indicate that taste perception may be associated with measures of adiposity in women. Taken together, these results highlight the importance of using appropriate control variables in research and indicate that a single measure of PROP perception may not adequately reflect the full effect of individual differences in taste perception on tobacco use or alcohol use and misuse. Since PROP perception was associated with differences in adiposity in women, however, individual differences in taste perception may be of public health importance. Future research should use continuous measures of a wider range of taste stimuli, to establish how taste perception (rather than just bitterness perception) affects health. Research should also ensure that covariates associated with tobacco use, alcohol use and misuse and adiposity (such as sex, SES and IQ) are included in analyses.

Erratum inserted on front fly leaf. / Bibliography: p. 283-315. / xiv, 315 p., [3] leaves of plates : ill. (one col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / To establish whether altered sulphation in cystic fibrosis could be demonstrated in different experimental systems, by focusing on glycosaminoglycans. The second aim was to establish the molecular basis for such a phenomenon. / Thesis (Ph.D.)--University of Adelaide, Dept. of Paediatrics, 1995

Bibliography: leaves 199-233. / xvii, 233 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Describes the development of a method used for quantification of cytokine mRNA expression and its application to measuring changes in cytokine expression in the synovial tissue and lymph notes draining the hind feet of rats with adjuvant arthritis (AA). / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1998?

Includes bibliography: (p. 96-104) / vii, 104 p. : ill. (some col.) ; 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, 1998