Pancreatic cancer (PC) is the fourth leading cause of cancer death in Western societies. Despite significant progress in understanding the molecular pathology of PC and its precursor lesion: pancreatic intraepithelial neoplasia (PanIN), there remain no molecules with proven clinical utility. Affymetrix Genechipfi oligonucleotide microarrays were used to interrogate mRNA expression of PC and normal pancreas to identify molecular pathways dysregulated in PC. Analysis of these data identified altered expression of numerous components of the S100 Calcium Binding Protein Family, Retinoic Acid signalling pathway and the HOX transcriptional network in PC compared to normal pancreas. These pathways were assessed using immunohistochemistry (IHC) and in-situ hybridisation (ISH) in a cohort of patients with PC. Increased protein expression, of S100A2, S100A6 and S100P was observed in 43%, 60% and 48% of PC respectively. Expression of S100A2 was associated with a poor outcome (p = 0.009), whilst increased expression of S100A6 (p = 0.0008) and S100P (p = 0.0005) were associated with an improved outcome. Additionally, S100A2 expression was identified as an independent marker of outcome in resected tumours. Aberrant expression of retinoic acid signalling components was demonstrated in PC cell lines using semi-quantitative RT-PCR. ISH demonstrated expression of Retinoic Acid Induced 3 (RAI3), an orphan G protein coupled receptor normally expressed in the fetal lung, in 68% of PC, and this co-segregated with an improved overall survival (p = 0.026).Ectopic protein expression of HOXB2, a transcription factor normally expressed in the developing hindbrain and modulated by retinoic acid, was observed in 15% of early PanIN lesions and 38% of PC specimens. Expression of HOXB2 was associated with non-resectable tumours and was an independent predictor of poor survival in resected tumours. Suppression of HOXB2 protein expression using small interfering RNA, resulted in epithelioid trans-differentiation in the Panc-1 PC cell line, however no alteration in proliferation rates were observed compared to controls. This thesis has shown that transcript profiling and tissue validation has identified potential markers of early diagnosis and outcome in PC. Furthermore, pathways and molecules previously thought to be associated with normal human development have been implicated to play a role in the development and progression of PC. Further analyses of these markers will determine any potential role in future diagnostic and therapeutic strategies.

Diversity analysis of Escherichia coli have routinely utilised isolates obtained by culture of faeces on MacConkey selective media, under the assumption that the diversity identified in faecal isolates are representative of similar diversity in E. coli in the gastrointestinal tract (GIT). This study has addressed this important issue by specifically isolating E. coli from different regions of the gut in pigs and subjecting them to enzymatic multilocus enzyme electrophoresis (MLEE) and molecular virulence factor (VF) analysis to ascertain whether E. coli populations inhabiting different regions of the gut are different from each other. Combination of these results showed that on average, E. coli strains isolated from the upper GIT region (small intestine) of the pig are distinctly different from the E. coli strains isolated from the lower GIT region (large intestine). An important aspect of the finding that faecal E. coli are not truly representative of the diversity in the GIT is the mechanism used by specific clonotypes that have adapted to different geographical habitats to survive challenge from incoming strains. / Doctor of Philosophy (PhD)

Throughout history a diversity of animal species have been used and studied extensively in the development of vaccines for the benefit of humans and animals alike. As mice are a relatively easy species to maintain, handle and manipulate, and have the advantage of being cost effective, they are commonly employed as animal models in the investigation of immunisation strategies against mucosal associated pathogens. Vaccine research against the human gastric pathogen Helicobacter pylori is extensively conducted in a mouse model and typically uses intra-gastric administration for the testing of potential vaccine candidates. An inherent complication with this route, however, is that the vaccine constituents may be inadequately delivered to sites of specific immunity and consequently may not be the optimal method for vaccine delivery. In the present study a mouse model of H. pylori infection was used to determine the efficacy of alternate mucosal routes of immunisation from examination of protective immunity, immune responses and the practical aspects of vaccine administration. Commencing with the optimisation of intra-intestinal immunisation, the direct injection of a H. pylori vaccine to initiator sites of the mucosal immune system established baseline data of dose rates for the comparative analysis of intra-gastric, intra-nasal and intra-rectal immunisation. Following the development of simple administration techniques whilst maintaining the welfare of the animals, intra-nasal immunisation was shown to elicit the highest level of prophylaxis against H. pylori challenge. Effective prophylaxis was also shown to be dependent upon a specific ratio of the vaccine constituents. When using whole cell lysate of H. pylori and the mucosal adjuvant cholera toxin, the ratio of antigen:adjuvant for optimal protective immunity was 10:1. The outcomes of this study have proved conclusively the necessity for optimisation of all aspects of immunisation in an animal model of infection. / Master of Science (Hons)

Transpyloric flow is the final step in gastric emptying prior to intestinal absorption of nutrients and medications. The details of this process are still incompletely understood. Transpyloric flow is bi-directional, contrasting with the general perception of solely forward flow implied by studies of gross gastric emptying. The degree to which the patterns of bi-directional transpyloric flow reflect emptying of meals of varied physicochemical composition, its mechanical determinants and effect on delivery of oral medications have been evaluated by the studies presented in this thesis.

Although a vast literature attests to the belief that psychosocial disturbance is an important component of functional gastrointestinal disorders (FGID), the relation of life stress, psychological distress and personality to the development of these disorders is poorly understood. The broad objective of this thesis is to provide data on relations between psychosocial factors and FGID, especially irritable bowel syndrome (IBS) and functional dyspepsia (FD), in representative outpatient samples. Issues not previously addressed are examined in a series of studies. The first two studies are concerned with relations between psychosocial factors, extraintestinal (somatic) symptoms and the number and type of FGID syndromes present at consultation and, in IBS patients, the prospective relation of psychosocial factors to changes in symptom intensity over 16 months. The last three studies relate psychosocial factors to gastrointestinal (GI) transit, motor, and sensory function in FGID, abnormalities in these parameters representing the putative origin of symptoms in FGID. In total, 350 patients participated, representing a 95% participation rate. Important features of the methodology include the use of a recently standardised symptom-based classification system for FGID, an objective and reliable interview-based life stress instrument (The Life Events and Difficulties Schedule), and sophisticated and sensitive technologies to assess GI transit, motor and sensory function. Novel measures, which conceptually take into account the chronic, fluctuating and recurrent course of IBS and FD syndromes, and the tendency of these syndromes to coexist, are also included. Thus, measures of symptom outcome assess the number of syndromes present, while the symptom intensity variable reflects the severity and frequency of both FD and IBS symptoms, if both are present. Similarly, with respect to altered transit, and motor and sensory function, physiological outcome variables reflect not only the presence of an abnormality but the number of regions affected, and the type and number of abnormalities present. Cross-sectional findings showed for the first time that psychosocial disturbance is associated with FGID symptomatology in a quantitative manner, that chronic life stress threat is central to this process and this stress-related process is a prominent feature of a particular group of syndromes (ie IBS/FD) defined primarily by the presence of pain and discomfort. A combination of psychological, social and biological factors combined to predict the number of FGID syndromes present at entry into the study. Prominent among them was an angry, reactive and anxious (neurotic) personality, chronic life stress threat, increased coping, poor emotional support and increased age. In addition to a greater number of FD/IBS syndromes, individuals with an anger-reactive response style had experienced more intense pain and discomfort, and displayed more complete sensorimotor disturbance. Longitudinal data demonstrated (also for the first time) the strength, consistency and unequivocal direction of the relation of chronic threat to symptom intensity over time. Almost all of the within subject variance in symptom intensity levels (assessed on 3 occasions over a 16 month period) was explained by the severity of chronic threat during the previous 6 months or more. For 76% of IBS patients, the presence vs the absence of one or more highly threatening chronic stressors predicted with considerable precision, the long-term clinical outcome. Thus, no patient exposed to even one such stressor improved clinically (ie by at least 50%) over the follow-up period, while in contrast, all patients who improved clinically did so in the absence of such a stressor. For 24% of patients, however, failure to improve clinically could not be explained by any psychological, social (including life stress) or demographic factor included in this study. Key risk indicators of a poor outcome at 16 months were identified - chronic life stress threat, the severity of baseline GI symptomatology, and female gender. Life stress is important because it alone determined the magnitude and direction of change in symptom intensity over time, while the severity of baseline GI symptomatology revealed the extent of improvement required to achieve a recovery, and female gender predicted the presence of a larger number of FD/IBS syndromes in women long-term. Widespread hypomotility, which was almost exclusive to women in this study, represents one factor that may inhibit improvement (or rate of improvement) for women over time. Finally, these findings have identified a psychophysiological subgroup, with underlying psychosocial, motor (and perhaps also sensory) dysfunctions that are more specific for women than men, and which does not seem to be distinctive of any particular FGID subgroup.

Bibliography: leaves 209-252. / xvi, 252 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Aims to develop and apply accurate methods of measurement of pyloric motor function and gastric emptying to an unsedated large animal preparation. / Thesis (D.M.)--University of Adelaide, Dept. of Surgery, 1994?

"April 2004" / Bibliography: leaves 121-142. / xviii, 142, [19] leaves : ill. (some col.), plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Attempts to build a complete understanding of the cellular mechanisms associated with gastrointestinal mucositis through investigations of the effects throughout the gastrointestinal tract of chemotherapeutic agents Methotrexate and Irinotecan, the possible ameliorating potential of the cytokine Interleukin-11 in reducing the side effects of chemotherapy, the expression of pro- and anti-apoptopic proteins and transcription factors along the gastrointestinal tract in normal human patients and the time-course of development of oral mucositis in human patients. Suggests that the entire gastrointestinal tract follows a similar pattern of development of mucositis. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2004

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

A new model for an adult human gastrointestinal tract (GIT) has been developed for use in internal dose estimations to the wall of the GIT and to the other organs and tissues of the body from radionuclides deposited in the lumenal contents of the five sections of the GIT. These sections were the esophagus, stomach, small intestine, upper large intestine, and the lower large intestine. The wall of each section was separated from its lumenal contents. Each wall was divided into many small regions so that the histologic and radiosensitive variations of the tissues across the wall could be distinguished. The characteristic parameters were determined based on the newest information available in the literature. Each of these sections except the stomach was subdivided into multiple subsections to include the spatiotemporal variations in the shape and characteristic parameters. This new GIT was integrated into an anthropomorphic phantom representing both an adult male and a larger-than-average adult female. The current phantom contains 14 different types of tissue. This phantom was coupled with the MCNP 4C Monte Carlo simulation package. The initial design and coding of the phantom and the Monte Carlo treatment employed in this study were validated using the results obtained by Cristy and Eckerman (1987). The code was used for calculating specific absorbed fractions (SAFs) in various organs and radiosensitive tissues from uniformly distributed sources of fifteen monoenergetic photons and electrons, 10 keV - 4 MeV, in the lumenal contents of the five sections of the GIT. The present studies showed that the average photon SAFs to the walls were significantly different from that to the radiosensitive cells (stem cells) for the energies below 50 keV. Above 50 keV, the photon SAFs were found to be almost constant across the walls. The electron SAF at the depth of the stem cells was a small fraction of the SAF routinely estimated at the contents-mucus interface. Electron studies showed that the “self-dose” for the energies below 300 keV and the “cross-dose” below 2 MeV were only from bremsstrahlung and fluorescent radiations at the depth of the stem cells and were not important.

Ingestion exposure estimates typically use a default bioavailability of 100%, thereby assuming that the entirety of an ingested dose is absorbed into systemic circulation. However, the actual bioavailability of ingested contaminants is oftentimes lower than 100%. The research described herein investigates the use of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) for the calculation of <i>in vitro</i> bioaccessibility (IVBA), a conservative predictor of bioavailability, of mercury (Hg) from traditional northern foods and arsenic (As) from soils. The primary objective of the research described herein is to address data-gaps which have hindered attempts to incorporate IVBA into risk assessment on more than a case-by-case basis. The hypotheses of this thesis are that (1) the bioaccessibility of contaminants is dependent upon concentration due to kinetic limitations on dissolution, (2) gastrointestinal (GI) microbes in the ileum and colon alter contaminant bioaccessibility and/or speciation, (3) the GI microbial effect on bioaccessibility is toxicologically relevant, and (4) metal bioaccessibility is predictable according to dissolution kinetics.<p> Mercury bioaccessibility from country food samples was independent of total Hg concentration (F=0.5726, P=0.578) whereas As bioaccessibility was inversely related to total As concentration for Nova Scotia mine tailings, synthesized ferrihydrite with adsorbed AsV, and synthesized amorphous scorodite (P=2 x 10-10). Isotherm analysis indicated that, at high soil As concentrations, saturation of simulated GI fluids limited As bioaccessibility under gastric conditions whereas kinetic limitations constrained As bioaccessibility under intestinal conditions. Additionally, we demonstrated that GI microbes may affect Hg bioaccessibility, either increasing or decreasing bioaccessibility depending upon the type of food. For example, the bioaccessibility of HgT decreased in the presence of GI microbial activity for caribou kidney, caribou tongue, seal blood, seal brain, seal liver, and walrus flesh. In contrast, HgT bioaccessibility from Arctic char and seal intestine increased in the presence of GI microbial activity. Similarly, colon microbial activity increased (Fishers Protected LSD, P<0.05) As bioaccessibility from synthesized amorphous scorodite (56 110%), Nova Scotia mine tailings (140 300%), an agricultural soil (53%) and an ironstone soil (350%) containing elevated arsenic concentrations. However, under small intestinal conditions, this microbial effect was transient and demonstrated a small effect size. The toxicological relevance of microbial effects upon As bioaccessibility was assessed using a juvenile swine model with co-administration of oral antibiotics (neomycin and metronidazole). This study research indicated that microbial effects on As bioaccessibility are not reflected in the juvenile swine model. For example, the microbial communities present in the pigs proximal colon clustered according to antibiotic treatment (e.g. microbial communities of antibiotic treated pigs differed from non-treated pigs). Despite this, the urinary arsenic excretion (and hence arsenic bioavailability) of antibiotic-treated juvenile swine orally exposed to soil-borne arsenic was equivalent (Holm-Sidak, P=0.930) to the urinary arsenic excretion of juvenile swine not treated with antibiotics. Therefore, in vitro GI models may not need to include a microbially active intestinal stage when measuring As IVBA.<p> Metal bioaccessibility from soils appears predictable according to fundamental chemical properties of the metal-of-concern. Specifically, metal bioaccessibility of 7 of the 13 metals (V, Ni, Zn, Cu, U, Cd, & Ba but not Tl, Pb, As, Se, Cr, and Hg) regulated according to Canadian Council of Ministers of the Environment Soil Quality Guidelines (CCME SQG) were strongly dependent (R2 = 0.7) on water exchange rate constants of metal cations (kH20) indicating that desorption kinetics may serve as the foundation of a predictive model of metal bioaccessibility.