Chloroform methanol (CM) soluble extract of a cereal-based diet has been suggested to induce type 1 diabetes in an experimental animal model of type 1 diabetes. However, the individual constituent of this extract responsible for the disease induction and its disease pathogenesis mechanism remained unexplored. A previous study in our laboratory failed to show that the sphingolipid enriched fraction of CM soluble extract of wheat gluten triggers type 1 diabetes. Therefore, to study the involvement of CM soluble gliadin proteins in type 1 diabetes, we retrospectively analyzed proteins from sphingolipid enriched extract. SDS-PAGE analysis of CM soluble extract of wheat gluten and sphingolipid enriched fraction exhibited protein bands corresponding to the masses of the wheat gliadins, suggesting the presence of gliadin proteins in the CM soluble sphingolipid enriched extract. We studied the effect of five different dietary treatments on the histopathology of pancreatic tissue from BBdp rats includes insulitis scores i.e. lymphocytic infiltration in islet of Langerhans in order to test gliadin specific sphingolipid enriched extract (GSLEE) as possible a diabetogen. However, there were no significant differences in pancreatic insulitis scores and lymphoid tissue content due to addition of (GSLEE) to the hydrolyzed casein (HC) diet. We also investigated changes in jejunal histopathology and sera IFN-γ, TNF-α cytokine concentration in type 1 diabetes, induced by GSLEE. A decrease in jejunal CD4+ and γδ TCR + cell counts and inflammatory cell infiltrate were observed due to presence of CM soluble GSLEE in the HC diet, although this decrease was not statistically significant. A significant increase in sera IFN-γ cytokine concentration was found in BBdp rats fed the HC + GSLEE diet as compared to rats on HC diet. A numerical decrease in sera TNF-α concentration was also observed in BBdp rats fed the HC + GSLEE diet, when compared to BBdp rats on the HC diet. In contrast, a significant increase in serum IFN-γ concentrations in BBdp rats were observed after removing the CM soluble GSLEE from the wheat gluten based diet (WG) when compared to the WG diet alone. Removing GSLEE from WG diet resulted in insignificant increase in serum TNF-α concentration in BBdp rats when compared to WG dietary treatment group's BBdp rats. However, there were no significant differences in jejunal enteropathy parameters (i.e. lymphocytic infiltration, mucosal thickness, epithelial erosion, jejunal villi flattenings), jejunal CD4+ and jejunal γδ TCR+ cell counts; pancreatic insulitis scores, lymphoid tissue content after removing the CM soluble GSLEE from the WG diet when compared to the WG diet. Since overall findings regarding the CM soluble GSLEE's potential to induce type 1 diabetes by changing pancreatic and jejunal histopathology and elevating serum IFN-γ, TNF-α cytokine levels largely remained inconclusive, further investigations are warranted regarding immune suppression potential of the CM soluble sphingolipids in type 1 diabetes and the search of diabetogenic agents remaining in the residue after CM extraction. / Master of Science

An expert system to predict the fertility of beef heifers was developed using the A.I. Toolkit KAPPA-PC 2.33. The knowledge base was developed from scientific literature and from a beef cattle reproduction expert. The expert system computes an evaluation age, age both at the start and end of the breeding season, and weight per day of age to classify a heifer as having either a 3LOW2, 3GOOD2, or 3EXCELLENT2 likelihood of conception. The expert system summarizes the information that is entered into the computer and creates a text file of the summary. It also gives explanations for every prediction to help identify and alleviate any problem areas that may affect a heifer1s ability to reproduce. The program requires an IBM compatible computer installed with Windows 3.13 or greater. From simulated data for purebred or crossbred British cattle, there was 72% prediction agreement between the expert system and the expert. From analysis of historical data of Hereford-Angus crossbred cattle, heifers categorized as 3LOW2 and 3GOOD2 had significantly higher observed pregnancy rates than expected for each category. There was no significant difference between observed and expected pregnancy rates for heifers in the 3EXCELLENT2 category. Pregnancy rates for post-weaning and pre-breeding evaluations for the 3LOW2 heifers were found to be lower from the combined 3GOOD2 and 3EXCELLENT2 heifers at P=.03 and P=.06 respectively. Observed successful calving rates for heifers categorized as 3LOW2, 3GOOD2, and 3EXCELLENT2 did not differ significantly from the expected calving rates for each category. / Master of Science

No / Burkholderia cepacia is known to invade and survive within respiratory epithelial cells. Previous studies have employed transformed cell lines and it is not known whether the bacterium is capable of manifesting the same phenomena in primary cell culture. Two strains of B. cepacia of environmental (NCTC 10661) and clinical origin (C1359) were examined for their ability to invade and survive (over a 24 h period) within type II pneumocytes in primary culture using a gentamicin¿ceftazidime antibiotic protection assay. Both strains of B. cepacia were capable of invasion of type II pneumocytes in primary culture. Strain C1359 was capable of multiplying intracellularly as indicated by a seven-fold increase in the numbers of bacteria from 4¿24 h, whereas strain 10661, although unable to replicate intracellularly, was found to survive in the pneumocytes for at least 24 h. Future studies on the invasiveness of B. cepacia can employ A549 cells as a valid surrogate for primary cell culture assays which are time-consuming, labour-intensive and expensive to perform.

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2011-2012 / L'arthrite rhumatoïde (AR) est une maladie incurable affectant 1% de la population mondiale et ayant comme origine une auto-immunité systémique. Les mécanismes moléculaires derrière la pathogenèse de l'AR sont mal définis, mais il s'avère que plusieurs facteurs environnementaux et génétiques sont impliqués. Basé sur des évidences récentes que la lectine myéloïde inhibitrice MICL puisse être impliqué dans la pathogenèse de l'AR, nous avons réalisé une étude génétique suggérant que le gène codant pour MICL pourrait être associé avec l'AR. De plus, des analyses d'expression au niveau protéique de MICL ont permis d'observer son expression dans le synovium et dans le liquide synovial d'articulations atteintes d'AR. Finalement, nos résultats suggèrent que MICL se situe dans le même complexe protéique que la vimentine. Cette étude a le potentiel de mener à une meilleure compréhension de la pathogenèse de l'AR et au développement d'un nouveau biomarqueur pronostique ou thérapeutique pour la maladie.

Rhizobiales encompass a diverse group of microbes, ranging from free-living, soil-dwelling bacteria to disease-causing, intracellular pathogens. Although the lifestyle of these organisms vary, many genetic systems are well conserved. One system, named the AbcR/VtlR system, is found throughout rhizobiales, and even extends to bacteria in other orders within the Alphaproteobacteria. The AbcR sRNAs are an example of sibling sRNAs, where two copies of the abcR gene are typically present in the genome. The AbcRs are involved in the negative regulation of ABC-type transport systems, which are important components for nutrient acquisition. Although the AbcRs share several features amongst organisms, major differences can be found in their functional and regulatory redundancy, the targets they regulate and how they regulate them. Specifically, one major difference in the AbcRs lies in the nucleotide sequences utilized by the sRNAs to bind mRNA targets. In the present studies, the regulatory mechanisms of the AbcR sRNAs were further characterized in the mammalian pathogen Brucella abortus, and the full regulatory profiles of the AbcRs were defined in the plant pathogen Agrobacterium tumefaciens. As mentioned above, the AbcR sRNAs are important for the proper regulation of nutrient-acquiring transport systems in the Rhizobiales. Since these sRNAs are critical to the lifestyle of a bacterium, proper regulation of this system is key to survival. A LysR-type transcriptional regulator, named VtlR, was found to be the bonefide transcriptional activator of abcR1 in B. abortus. Furthermore, VtlR has been shown to be a key component in host interactions in several rhizobiales. The preset work has shed light on the evolutionary divergence of this regulator in bacteria, and further defined the regulatory capacity of VtlR in Agrobacterium. Overall, the studies described here have made significant advances in our knowledge of the AbcR/VtlR-regulatory systems in the Rhizobiales, and have further defined this system as being a vital part of host-microbe interactions. / PHD / Understanding the genetic systems utilized by microbes to cause infection is key for developing therapeutics that can be administered to fight against them. Moreover, identifying and characterizing these essential microbial systems can be exploited for the development of drugs to target and shut down these systems, thus causing cell death. The present work took a basic molecular biology approach and characterized a highly conserved genetic system, named the AbcR/VtlR system, in two pathogenic bacteria: the plant pathogen Agrobacterium and the mammalian pathogen Brucella. Overall, the work described here shows this system to be an important component in acquiring nutrients for the microbe, and, most importantly, found the AbcR/VtlR system to be essential for host-microbial interactions.

Yes / Individuals with type 2 diabetes play a pivotal role in their health. Enhancing the self-management of diabetes can improve blood glucose control, and quality of life, and reduce diabetes-related complications. We have identified factors influencing the self-management of type 2 diabetes to inform strategies that may be applied in the long-term management of blood glucose control. Methods: We conducted a systematic literature review of recent studies published between January 2010 to December 2020 to identify the available evidence on effective self-management strategies for type 2 diabetes. The databases used for the searchers were Scopus, PubMed, Science Direct, CINAHL, and Google Scholar. We assessed English language publications only. The screening of titles was duplicated by two researchers. We then conducted a thematic analysis of the key findings from eligible publications to identify reoccurring messages that may augment or abate self-management strategies. Results: We identified 49 relevant publications involving 90,857 participants. Four key themes were identified from these publications: Individual drive, social capital, Knowledge base, and Insufficient health care. High motivation and self-efficacy enabled greater self-management. The importance of family, friends, and the health care professional was salient, as were the negative effects of stigma and labelling. Enablers to good self-management were the level of support provided and its affordability. Finally, the accessibility and adequacy of the health care services emerged as fundamental to permit diabetes self-management. Conclusions: Self-management of type 2 diabetes is an essential strategy given its global presence and impact, and the current resource constraints in health care. Individuals with type 2 diabetes should be empowered and supported to self-manage. This includes awareness raising on their role in self-health, engaging broader support networks, and the pivotal role of health care professionals to inform and support. Further research is needed into the capacity assessment of healthcare systems in diabetes medicine, targeted low-cost resources for self-management, and the financial requirements that enable self-management advice to be enacted. / While this research did not receive any specific project funding, KRB is funded by a University of Otago Pacific Ph.D. Scholarship. ANR is funded as a Research Fellow by the National Heart Foundation.

Les avancées diérapeutiques, résultant de trois décennies d'intenses recherches, ont considérablement changé la physionomie de l'infection au virus de l'immunodéficience humaine de type 1 (VIH-1). Chez les patients recevant une thérapie antirétrovirale hautement active, les maladies du foie sont devenues la principale cause de décès hors-SIDA. Par ailleurs, des évidences croissantes démontrent que la muqueuse intestinale est le foyer majeur de la replication virale et par conséquent un site clé dans la pathogénèse de la maladie. Cette muqueuse est directement reliée au foie qui, par sa localisation au carrefour de la circulation sanguine générale et entérique, constitue l'organe clé de la filtration du sang en provenance des intestins. Dans cette étude, nous nous sommes donc intéressés au rôle du foie et plus particulièrement des hépatocytes, la cellule parenchymateuse hépatique, dans la padiogénèse de l'infection au VIH-1. Nous avons ainsi tenté de caractériser les interactions entre le VIH-1 et les hépatocytes. Dans un premier temps, nous avons fait état de la faible susceptibilité à l'infection par le VIH-1 d'une lignée hépatocytaire. Nous avons aussi démontré que la restriction principale à l'infection des hépatocytes est l'absence du récepteur CD4 et que cette restriction peut être contournée par l'utilisation du glycolipide GalCer par certaines souches virales pour permettre la fusion. Dans un second temps, nous avons mis en évidence la capacité des hépatocytes à transmettre en tram à des lymphocytes T CD4⁺ activés des particules virales liés à leur surface. Ce mode d'infection très efficace nécessite l'interaction de la molécule ICAM-1 exprimée sur les hépatocytes avec la molécule LFA-1 des lymphocytes T CD4⁺ activés. Cette émde présente un nouveau moyen pour le virus d'infecter très efficacement des sous populations de lymphocytes T CD4⁺ spécifiquement enrichies dans le foie. Globalement, les résultats de nos travaux associés aux connaissances croissantes sur l'immunité du foie nous conduisent à penser qu'il serait essentiel d'analyser l'impact des mécanismes immunitaires contrôlés par le foie sur le cercle vicieux de l'immunopatiiogénèse de l'infection au VIH-1.

Nutrient loss has been a problem in the agricultural field for as long as fertilizers have been used. Not only is it cost inefficient, it can be an environmental hazard when these nutrients enter the watershed. Biochar, both untreated and treated, have been shown to improve soil’s ability to retain nutrients and increase residency time. However, the sorption capacity of biochar when amended with different soil types, has not been explored sufficiently. Batch reactors and sediment columns were used to determine the efficiency of magnesium oxide treated biochar in three different soil types to retain nitrates and phosphates. The results showed that while largely ineffective for nitrate amendment, this approach could be very effective for the amendment of phosphates in all three soil types. Kinetic studies showed that effectiveness was immediate with phosphates. Absorption occurred more slowly with nitrates, and after a time effectiveness was reversed.

Plus de 25 ans après l'identification du VIH-1 comme agent étiologique responsable de l'épidémie du SIDA et malgré un effort de recherche considérable, il nous est toujours impossible de guérir la maladie et aucun vaccin efficace n'a pu être mis au point. Pourtant de nombreuses découvertes ont été faites et le cycle viral du VIH-1 est aujourd'hui relativement bien détaillé, notamment en ce qui a trait aux cellules ciblées par le virus ainsi qu'aux étapes précoces menant à l'infection. On sait par exemple que la principale interaction permettant l'infection d'une cellule cible est celle entre la gp120 virale et le récepteur cellulaire CD4. On sait également que cette interaction est par nature plutôt faible, mais que d'autres interactions moléculaires entre le virus et la cellule peuvent stabiliser la liaison et ainsi mener à une infection productive. De même, certaines molécules peuvent avoir un effet inhibiteur sur l'infection au VIH-1 en empêchant la liaison entre la gp120 et le CD4. C'est le cas de plusieurs lectines qui ont montré un intéressant potentiel d'inhibition lorsqu'elles se lient aux glycanes de la gp120. Bien qu'elle soit également une lectine, la galectine-1 a démontré un tout autre impact sur l'infection au VIH-1. Cette molécule humaine est largement exprimée par les cellules cibles du VIH-1 et par d'autres cellules présentes dans leur environnement. Nos recherches démontrent clairement que la galectine-1 potentialise l'infection au VIH-1 en stabilisant l'attachement du virus sur la cellule cible mais sans augmenter de façon directe le processus de fusion. Nous avons observé ce phénomène avec des virus de tropisme différent et sur les deux types cellulaires représentant les principales cibles du VIH-1, soit les lymphocytes T CD4+ et les macrophages. Nous avons également observé que la galectine-1 facilite le transfert de virions de tropisme X4 des macrophages vers les lymphocytes T CD4+. Ces données nous indiquent que la galectine-1 favorise considérablement l'infection au VIH-1, mais aussi qu'elle pourrait agir comme un récepteur éboueur (scavenger receptor) soluble lorsque la fusion virale est inhibée.

Au cours des dernières années, la galectine-1 (Gal-1) a été reconnue comme étant une molécule de l'hôte pouvant perturber la réponse immunitaire soit par son interaction directe avec les cellules impliquées, soit par la modulation d'interaction hôte-microorganisme. Les études présentées dans cette thèse visent à comprendre les mécanismes d'action caractéristiques à la galectine-1 qui potentialisent l'infection du virus d'immunodéficience humaine de type 1 (VIH-1) chez les lymphocytes T CD4+ et les macrophages. Les résultats obtenus ont pu démontrer l'interaction directe entre la gal-1 et le VIH-1 et que cette interaction est dépendante de l'entassement des oligosaccharides (glycans) N-liés de type complexe à la surface de la gpl20. De plus, des composés synthétiques ont été développés pour inhiber spécifiquement l'action de la galectine-1 dans la pathogenèse du VEH-1. Ces données permettent donc de mieux comprendre la spécificité de l'interaction de la galectine-1 avec la particule virale et suggèrent des moyens pour en réguler l'activité.