Preeclampsia is a hypertensive disorder of pregnancy that is diagnosed after the 20th week of gestation. It is defined by the American College of Obstetrics and Gynecology as de novo hypertension of at least 140/90 in a pregnant woman. Proteinuria with the hypertension is sufficient but not required for the diagnosis, especially if a woman displays severe symptoms such as headache, blurry vision, right upper quadrant pain, and low platelet count. Despite significant research, preeclampsia continues to kill 76,000 mothers and 500,000 babies per year worldwide. It causes short and long term consequences such as future metabolic and cardiovascular events for the mother and the child born during a pregnancy affected by preeclampsia. A delay in diagnosis and delayed access to appropriate care is a core cause of the preeclampsia related morbidity and severe mortality worldwide. Despite being in the medical literature since the time of the ancient Greeks, there is currently no significant predictive, preventative, therapeutic, and curative agent for preeclampsia except for an often preterm delivery of the fetus. The complex pathogenesis of preeclampsia has challenged the ability to effectively predict preeclampsia to decrease the delay in this diagnosis. Consequently, an early intervention or triage to higher level obstetric care is hindered. The lack of an early biomarker for preeclampsia also represents a major barrier to treat preeclampsia before major clinical symptoms emerge and the cycle of future cardiovascular risk for mom and baby begins. Novel, very early pregnancy predictive tests for preeclampsia may provide significant clinical utility. Furthermore, a biomarker that is linked with an early pathogenic mechanism in the first trimester development of preeclampsia would reveal a new avenue of early, first trimester intervention to treat and prevent this devastating disease. This work details the search for such a biomarker linked to an early initiator of the molecular pathogenesis of preeclampsia. These microRNA data highlight very important dysregulated mechanisms including immunologic, cell growth, and angiogenic mechanisms. T cells and the role of indoleamine 2,3 dioxygenase (IDO) is important in the early, maternal immune tolerance to the placenta and pregnancy. As poor placentation is a core cause of preeclampsia, a decreased immune tolerance to it is hypothesized to lead to preeclampsia. Furthermore, low IDO activity has been observed in the placentas of preeclamptic pregnancies which may make it a viable biomarker. These IDO-knock out mouse data, demonstrate that chronic IDO deficiency is sufficient to cause some of the core phenotypes of preeclampsia including renal dysfunction, vascular endothelial dysfunction, fetal growth restriction, and a slight increase in systolic blood pressure. This model does not completely phenocopy human preeclampsia. An investigation of early markers that are linked to vascular, immune, and renal abnormalities highlights the vasopressin pathway as a potential biomarker and early initiator of the pathogenesis of preeclampsia. These data demonstrate that copeptin, as a stable marker of vasopressin secretion, is robustly predictive of the development of late pregnancy human preeclampsia, as early as the 6th week of gestation. Furthermore, a mouse model with chronic infusion of vasopressin throughout mouse gestation phenocopies all the essential aspects of human preeclampsia: pregnancy specific hypertension, proteinuria, pathognomonic glomerular endotheliosis, fetal growth restriction, and increased fetal death. Further research must be done to elucidate the immunologic, vascular, and fetal programming phenotypes of this model. This work posits the possibility that the vasopressin pathway may provide new predictive, preventative, therapeutic, and potentially curative modalities for preeclampsia.

Le myélome multiple (MM) est un cancer hématologique qui se caractérise par une prolifération et une accumulation de cellules plasmocytaires malignes au niveau de la moelle osseuse (MO). Il représente 10% des hémopathies malignes et 2% de la mortalité par cancer dans le monde occidental. La principale conséquence de l’expansion plasmocytaire clonale médullaire est la sécrétion excessive d’une immunoglobuline (Ig) unique qui va être à l’origine du caractère multi-symptomatique de cette pathologie. Ainsi, les manifestations du MM se caractérisent par des lésions osseuses, une atteinte rénale, une anémie, une hypercalcémie et une immunodéficience humorale conduisant à des infections récidivantes. Son pronostic est mauvais avec une médiane de survie qui se situe entre cinq et sept ans sous chimiothérapie qui vise à éliminer les cellules plasmocytaires malignes.A partir de la lignée U266 de myélome, nous avons dérivé des clones résistants au bortézomib (R6). Grâce à une analyse par biopuces à ADN, nous avons identifié 160 gènes significativement régulés dans les cellules R6 par rapport à la lignée parentale U266. Nous avons établi, par une approche fonctionnelle, que la surexpression de la protéine HspB8 conduit, via l’activation de la dégradation autophagique, à l’élimination des agrégats protéiques et à compenser l’effet de l’inhibition du protéasome conférant ainsi la résistance des cellules de myélome aux inhibiteurs du protéasome.Dans un second temps, nous nous sommes intéressés à l’implication de la protéine Bcl-B (BCL2L10) dans la pathogenèse du MM. Nous avons confirmé que Bcl-B est impliqué dans la pathogénèse du MM (patients et modèle murin). / Velcade is one of the inescapable drug to treat patient suffering from multiple myeloma (MM) and resistance to this drug represents a major drawback for patients. However, the mechanisms underlying velcade resistance remain incompletely understood. We derived several U266 MM cell clones that resist to velcade. We derived several U266 MM cell clones that resist to velcade. U266- resistant cells were resistant to velcade-induced cell death but exhibited a similar sensitivity to various proapoptotic stimuli. Careful analysis of proteosomal subunits and proteasome enzymatic activities showed that neither the composition nor the activity of the proteasome was affected in velcade-resistant cells.In addition, pangenomic profiling of velcade-sensitive and resistant cells showed that the small heat shock protein HSPB8 was overexpressed in resistant cells. Finally, gain and loss of function experiment demonstrated that HSPB8 is a key factor for velcade resistance. In conclusion, HSPB8 plays an important role for the elimination of aggregates in velcade-resistant cells that contributes to their enhanced survival. Multiple myeloma (MM) evolves from a premalignant condition known as monoclonal gammopathy of undetermined significance (MGUS). However, the factors underlying the malignant transformation of plasmocytes in MM are not fully characterized. We report an MM phenotype in transgenic mice with Eμ-directed expression of the Bcl-B protein. With age, Eμ-bcl-b transgenic mice develop the characteristic features of human MM. In addition, this MM-like disease is serially transplantable, underlying the tumoral origin of plasmocytes.

The Gram-negative bacterium Bartonella henselae (Bh) is an emerging zoonotic pathogen that has been associated with a variety of human diseases including bacillary angiomatosis which is characterized by vasoproliferative tumor-like lesions on the skin and internal organs of some immunosuppressed individuals. Several virulence factors associated with Bartonella-induced pathogenesis have been characterized. However, the study of those virulence factors has been limited to in vitro cell culture systems due to the lack of a practical animal model. Therefore, we wanted to investigate whether the zebrafish embryo (Danio rerio) could be used to model human infection with Bh. We investigated if Bh can mount an infection in zebrafish embryos during their early stage of development. Our data showed that Tg(fli1:egfp)y1 zebrafish embryos supported a sustained Bh infection for 7 days with >10-fold bacterial replication when inoculated in the yolk sac. This was evident by plating of zebrafish homogenates, quantitative PCR, and confocal microscopy analysis. We assessed the interaction of Bh with EC and the phagocytic cells in live embryos by microscopy. Our data showed that aggregates of Bh interact with the endothelium of the embryo vasculature. Evidence showed that Bh recruited phagocytes to the site of infection in the Tg(mpx:GFP)uwm1 embryos. We also wanted to determine the response to infection with Bh. Infected embryos showed evidence of a Bh-induced angiogenic phenotype as well as an increase in expression of genes encoding pro-inflammatory factors and pro-angiogenic markers. A deletion mutant for the entire VirB type IV secretion system (ΔvirB2-11 supported bacterial replication although to a lesser degree compared to the wild type control. However, infection of zebrafish embryos with a deletion mutant in the major adhesin (BadA) resulted in little or no bacterial replication and a diminished pro-angiogenic and pro-inflammatory host response compared to wild type Bh, providing the first evidence that BadA is critical for in vivo infection. Thus, the zebrafish embryo provides the first practical animal model of Bh infection that will facilitate efforts to identify virulence factors and define molecular mechanisms of Bh pathogenesis.

No description available.

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"8th July 2002." Includes bibliographical references (leaves 276-308) Examines the systematics (taxonomy, phylogeny, and epiemiology) of the genus Candida using a combination of traditional and contemporary methodologies. Assesses these methods to determine their diagnostic potential to unequivocally identify and characterise species and strains of this medically and dentally important yeast genus.

"December, 2002" Includes bibliographical references (leaves 211-238)

[Truncated abstract] Iron is essential to most biological systems. Under pathological conditions affecting the iron metabolic pathway, iron can be deposited in the tissue in various forms. The work presented in this thesis has exploited the relationship between the magnetic and the chemical properties of tissue iron deposits to further understanding of two major pathologies, the haemoglobinopathies termed thalassaemias and the malaria parasite Plasmodium falciparum, both amongst the most common health concerns in tropical countries. The iron-specific magnetic susceptibilities ¿Fe for spleen tissue samples from 7 transfusion dependent ß-thalassaemia (ß-thal) patients and 11 non-transfusion dependent ß-thalassaemia/Haemoglobin E (ß/E) patients were measured at 37°C. Both groups of patients were iron loaded with no significant difference in the distribution of spleen iron concentrations between the two groups. There was a significant difference between the mean ¿Fe of the spleen tissue from each group. The ß/E patients had a higher mean (± standard deviation) spleen ¿Fe (1.55 ± 0.23 × 10-6 m3.kgFe -1) than the ß-thal patients (1.16 ± 0.25 × 10-6 m3.kgFe -1). Correlations were observed between ¿Fe of the spleen tissue and the fraction of magnetic hyperfine split sextet in the 57Fe Mössbauer spectra of the tissues at 78 K (Spearman rank order correlation ¿ = -0.54, p = 0.03) and between ¿Fe of the spleen tissue and the fraction of doublet in the spectra at 5 K (¿ = 0.58, p = 0.02) indicating that ¿Fe of the spleen tissue is related to the chemical speciation of the iron 2 deposits in the tissue. The biological variability of the iron-specific magnetic susceptibility of the tissue iron examined would contribute a random uncertainty of 19% to magnetic susceptibility based non-invasive measurements of tissue iron concentration. ... Magnetic susceptibility measurements were also performed on malaria parasitised red blood cells. In vitro cultures of P. falciparum were magnetically enriched up to 61-fold using high field gradient magnetic separation columns, and the magnetic susceptibility of cell contents was directly measured. Forms of haem iron were quantified spectroscopically. Further fractionations were performed such that, by controlling the fluid velocity through the column, cells with more than a critical amount of paramagnetic 3 iron were preferentially extracted. A chloroquine-sensitive (CQS) laboratory strain of parasites converted approximately 60% of host cell haem iron to haemozoin and this product was the primary source of the increase in cell magnetic susceptibility. The volumetric magnetic susceptibility of the magnetically enriched cells was found to be 0.15 ± 0.03 × 10-7 relative to the suspension medium, accounting for the enrichment of mature parasites. Comparisons of fractionation samples of two pairs of CQS and chloroquine resistant (CQR) strains showed enrichment of mature parasites was significantly greater in the CQS than the CQR strains. The results suggest the possibility of using magnetic separation columns in identifying CQR strains of P. falciparum, potentially in a diagnostic or research setting. The study also underlines the need to identify and quantify the forms of iron in CQR and CQS parasite strains as the fate of haem iron will have implications in understanding the mechanisms of chloroquine resistance.

Defects in fat metabolism are central to the aetiology and pathogenesis of obesity and type II diabetes. The liver plays a central role in these disease states via its regulation of glucose and fat metabolism. In addition, accumulation of fat within the liver has been associated with changes in key pathways of carbohydrate and fat metabolism. However a number of questions remain. It is hypothesised that fat accumulation within the liver is a primary defect in the aetiology and pathogenesis of obesity and type II diabetes. Fat accumulating in the liver is the result of changes in the gene expression of key enzymes and proteins involved with fat uptake, fat transport, fat oxidation, fat re-esterification or storage and export of fat from the liver and these changes are regulated by key lipid responsive transcription factors. To study these questions Psammomys obesus was utilised. This polygenic rodent model of obesity and type II diabetes develops obesity and diabetes in a similar pattern to susceptible human populations. In addition dietary and environmental changes to Psammomys obesus were employed to create different states of energy balance, which allowed the regulation of liver fat gene expression to be examined. These investigations include: 1) Measurement of fat accumulation and fatty acid binding proteins in lean, obese and diabetic Psammomys obesus. 2) Characterisation of hepatic lipid enzymes, transport protein and lipid responsive transcription factor gene expression in lean, obese and diabetic Paammomys obesus. 3) The effect of acute and chronic energy restriction on hepatic lipid metabolism in Psammomys obesus. 4) The effect of sucrose feeding on the development of obesity and type II diabetes in Psammomys obesus. 5) The effect of nicotine treatment in lean and obese Psammomys obesus, 6) The effect of high dose leptin administration on hepatic fat metabolism in Psammomys obesus. The results of these studies demonstrated that fat accumulation within the liver was not a primary defect in the aetiology and pathogenesis of obesity and type II diabetes. Fat accumulating in the liver was not the result of changes in the gene expression of key enzymes and proteins involved in hepatic fat metabolism. However changes in the mRNA level of the transcription factors PPAR∝ and SREBP-1C was associated with the development of diabetes and the gene expression of these two transcription factors was associated with changes in diabetic status.