- Einleitung - Coxiella burnetii (C. burnetii) ist der Erreger des Q-Fiebers, einer zoonotischen Erkrankung, welche insbesondere kleine und große Wiederkäuer betrifft. Während Tiere meist asymptomatisch erkranken, kann die Erkrankung beim Menschen von akuten grippeähnlichen Symptomen bis hin zur chronischen Organschädigung führen. Die Diagnostik von Q-Fieber im veterinärmedizinischen Bereich wird durch unspezifische Symptome sowie diagnostische Lücken erschwert: Einerseits ist die direkte Diagnostik aufgrund langer Anzuchtzeiten der Bakterien häufig unpraktikabel. Andererseits weisen die Leistungen der Serodiagnostika in Untersuchungen teilweise inakzeptable Spezifitäten und Sensitivitäten auf. - Ziel der Untersuchungen - Ziel war es, das Potential des rekombinant hergestellten C. burnetii Außenmembran-proteins Com1 als diagnostischen Marker zu bestimmen und darauf aufbauend einen indirekten Enzyme-linked Immunosorbent Assay (ELISA) zu entwickeln, welcher die Grundlage für neue, praxistaugliche und verbesserte Serodiagnostika bieten kann. - Material und Methoden - Hierfür wurde die kodierende Sequenz für Com1 von C. burnetii Nine Mile Phase II RSA 439 unter Ausschluss der Signalsequenz mittels Polymerase-Kettenreaktion amplifiziert. Das Amplifikat com1 wurde in ein Expressionsplasmid kloniert und anschließend mittels Transformation in Escherichia coli (E. coli) als Com1 exprimiert. Das Expressionsprodukt wurde nach der Aufreinigung über Nickel-NTA (Nitrilotriessigsäure) mittels SDS-PAGE (Natriumdodecylsulfat-Polyacrylamid-Gelelektrophorese), Coomassie-Blau-Färbung und Western Blot überprüft. Die 96-Well-Mikrotiterplatten wurden mit 1 µg/Well des rekombinanten Proteins beschichtet und 404 Seren von Schafen (111), Ziegen (100) und Rindern (193) auf ihre Reaktion im rekombinanten Com1-ELISA analysiert. Die Seren stammten sowohl aus definierten Ausbrüchen als auch aus Q-Fieber-freien Beständen, geimpften Herden und von Tieren mit fraglichem Infektionshintergrund. Daneben wurden die Seren mit kommerziellen ELISAs getestet und daraufhin in positive und negative Seren eingeteilt. Die OD450-Werte (optische Dichte bei 450 nm) der Seren aus dem rekombinanten Com1-ELISAs wurden in Pivot-Tabellen angeordnet und anschließend in einer ROC-Kurve (receiver operating characteristic) dargestellt, wodurch das Integral als Area under the curve (AUC) berechnet und hinsichtlich der Diskrimination zwischen positiven und negativen Ergebnissen ausgewertet wurde. Nach Festlegung von tierart-spezifischen Cut-off-Werten wurden Sensitivität und Falsch-Positiv-Rate bestimmt. - Ergebnisse - Die ermittelten tierart-spezifischen OD450-Cut-off-Werte betrugen für Schafe 0,32, für Ziegen 0,23 und für Rinder 0,18. Als Spezifität bzw. Sensitivität ergaben sich für Schafe 85 % bzw. 68 %, für Ziegen 94 % bzw. 77 % und für Rinder 71 % bzw. 70 %. Die Diskrimination wurde bei Schafen als „exzellent“, bei Ziegen als „herausragend“ und bei Rindern als „akzeptabel“ eingeschätzt. - Schlussfolgerungen - Die Ergebnisse dieser Studie zeigen, dass das Coxiella-Außenmembranprotein Com1 als Basis für die Entwicklung neuer, sensitiverer und spezifischerer (Schnell)-Diagnostika dienen kann, um weitere Q-Fieber-Epidemien einzudämmen und damit das Risiko einer C. burnetii-Infektion für Mensch und Tier zu minimieren. / - Introduction - Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease with small and large ruminants as the target hosts. While an infection in ruminants is often symptomless, the disease in humans can lead from acute flu-like symptoms to chronic organ damage. In addition to the non-specific symptoms in the veterinary field, for which reason it is difficult to directly conclude on a Q fever outbreak, the detection of infections with C. burnetii is in need of improvement. On the one hand, direct diagnosis is often impracticable due to long cultivation periods of the bacteria. On the other hand, the performance of serodiagnostics shows partially unacceptable specificities and sensitivities. - Objectives - The aim of the study was to determine the potential of the recombinantly produced C. burnetii outer membrane protein Com1 as a diagnostic marker and, subsequently, to develop an indirect enzyme-linked immunosorbent assay (ELISA), which can provide the basis for the development of new and improved serodiagnostics. - Material and methods - For this purpose, primers for com1 were designed in silico and the open reading frame (ORF) was amplified by polymerase chain reaction (PCR) using phenol-chloroform-isolated DNA (deoxyribonucleic acid) from C. burnetii Nine Mile Phase II RSA 439 without signal sequence. After control by gel electrophoresis, the amplified product was cloned into the two-stage gateway system (Invitrogen) and transformed into Escherichia coli (E. coli) TOP10. The expression vector was cloned into E. coli BL21(DE3) and Com1 was expressed. The protein was analyzed after native purification via Nickel-NTA (nitrilotriacetic acid) by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis), Coomassie blue staining and Western blot and subsequently concentrated. Microtiter plates were coated with the recombinant protein and 404 sera from sheep (111), goats (100) and cattle (193) were tested for their reaction in the recombinant Com1-ELISA. The sera were derived from 36 different flocks, both from defined outbreaks and from Q fever-free flocks, vaccinated herds and from animals with questionable infection background. In addition, the sera were tested with commercial ELISAs and could thus be divided into positive and negative sera. The OD450 values (optical density at 450 nm) of the sera from the recombinant Com1 ELISAs were arranged in pivot tables and then plotted on a ROC curve (receiver operating characteristic), allowing the integral to be calculated as the area under the curve (AUC) and evaluated regarding the discrimination between positive and negative results. After establishing animal species-specific cut-off values, sensitivity and false positive rate were determined. - Results - The animal species-specific OD450 cut-off values determined were 0.32 for sheep, 0.23 for goats and 0.181 for cattle. Specificity and sensitivity were 85 % and 68 % for sheep, 94 % and 77 % for goats and 71 % and 70 % for cattle. Discrimination was assessed as 'excellent' in sheep, 'outstanding' in goats and 'acceptable' in cattle. - Conclusions - The results of this study suggest that the Coxiella outer membrane protein Com1, together with other immunogenic marker proteins, may serve as a basis for the development of new more sensitive and specific diagnostic tools to contain further Q fever epidemics and thus minimize the risk of C. burnetii infection for humans and animals. Com1 could also lay the foundation for direct rapid diagnostics.

L'autophagie maintient l'homéostasie cellulaire en dégradant les composants cellulaires. Chez l'humain, les protéines LC3 jouent un rôle central dans l'autophagie en interagissant avec d'autres facteurs contenant des régions d'interaction LC3 (LIR). Cette thèse porte sur le rôle de différents facteurs contenant des LIR, tels que le facteur nucléaire DOR et la protéine NSs du virus de la fièvre de la vallée du Rift (VFVR). Les protéines LC3 sont principalement présentes dans le noyau des cellules au repos normales, et leur passage au cytosol en réponse au stress nécessite une interaction avec DOR. Récemment, il a été démontré que cette interaction entre DOR et LC3B dépend de la désacétylation de deux résidus lysine conservés (K49/K51 de LC3A et K46/K48 de GABARAP). Cependant, les détails mécanistiques du rôle des résidus lysine individuels dans le transfert d'autres protéines LC3 demeurent inconnus. De plus, la caractérisation de l'interaction NSs-LC3 ainsi que son impact sur l'autophagie lors de l'infection par le RVFV demeurent évasives. Par conséquent, l'objectif de ces études est d'investiguer les différences structurelles et fonctionnelles des protéines humaines LC3 à différents stades de l'autophagie via leur interaction avec DOR et NSs. Nos études biophysiques et structurales ont permis d’identifier des éléments clés déterminant la spécificité de la région d'interaction LC3 de DOR (DORLIR) pour GABARAP. Nos études structurales ont défini une conformation en feuillet  chez DORLIR lorsqu'elle est en complexe avec GABARAP, ce qui joue un rôle important dans l'établissement de cette spécificité. Les études structurales ont également montré que l'acétylation de la deuxième Lys de GABARAP ou LC3A perturbe des interactions clés du W35 de DORLIR, ce qui conduit à une diminution de l'affinité qui est cohérente avec nos résultats ITC. Ces résultats ont été confirmés grâce à des expériences cellulaires en utilisant des substitutions K-en-Q pour imiter l'acétylation des Lys. En cellules, les substitutions K-en-Q à la deuxième Lys ont entravé le transfert cytoplasmique de GABARAP et de LC3A, ainsi que leur colocalisation avec DOR, tandis que les substitutions K-en-Q à la première Lys se comportent comme des protéines de type sauvage. Dans l'ensemble, la désacétylation de la deuxième Lys conservée est cruciale pour le transfert cytoplasmique de GABARAP et LC3A lors de l'autophagie, ce qui diffère de ce qui a été observé auparavant avec LC3B, où la désacétylation des deux Lys était nécessaire. Cette étude fournit également des informations sur les interactions entre la protéine NSs du VFVR et les protéines LC3, ainsi que l'impact de NSs sur l'autophagie lors de l'infection par le VFVR. Nous avons identifié quatre motifs potentiels d'interaction LC3 (NSs1-4) dans la protéine NSs, et des études d’ITC ont démontré que NSs4 interagit avec une affinité sous micromolaire-micromolaire avec les protéines LC3 humaines. De plus, nous avons confirmé que les protéines LC3 interagissent avec NSs dans les cellules, et que chez les cellules infectées par le RVFV, LC3A colocalise avec NSs. Dans l'ensemble, les résultats indiquent que la protéine NSs joue un rôle clé dans la modification de l'autophagie lors des infections par le VFVR. / Autophagy maintains cellular homeostasis through catabolism of cellular components including organelles, proteins, and pathogens. In humans, the six LC3 (Microtubule-associated protein 1 light chain 3) protein (LC3A, LC3B, LC3C, GABARAP, GABARAPL1 and GABARAPL2) play a pivotal role in autophagy through interactions with other factors that contain LC3-interacting regions (LIRs). This study focuses on the role of different factors that contain LIRs such as the nuclear factor DOR and the NSs protein from the RVFV. LC3 proteins are predominantly present in the nucleus of normal resting cells and their shuttling to the cytosol in response to stress requires interaction with DOR. Recently, this interaction between DOR and LC3B was shown to depend on the deacetylation of two conserved Lys residues (K49/K51in LC3 subfamily proteins and K46/K48 in GABARAP subfamily proteins). However, the mechanistic details of the role of the individual Lys residues in the shuttling other LC3 proteins is unknown. In addition, the characterization of NSs-LC3 interaction as well as its impact on RVFV (Rift Valley fever virus) infection on autophagy remains elusive. Therefore, the goal of these studies is to investigate the structural and the functional differences of the six human LC3 proteins in different stages of autophagy through their interaction with DOR and NSs. Our biophysical and structural studies identified key elements determining the specificity of the LIR from DOR (DORLIR) for the GABARAP subfamily. Our structural studies defined a -sheet conformation in DORLIR when complexed with GABARAP, which is important role for establishing this specificity. ITC studies with acetylated versions of LC3A and GABARAP demonstrated that acetylation of the second Lys significantly decreases binding to the DORLIR whereas acetylation at the first Lys has little to no effect. Our structural studies also demonstrate that acetylation at the second Lys of either GABARAP or LC3A disrupts key interactions between W35 of the DORLIR, which leads to the decreased affinity. The in vitro results were verified in cellular experiments using K-to-Q substitutions to mimic Lys acetylation. In cells, K-to-Q substitutions at the second Lys impaired the cytoplasmic shuttling of both GABARAP and LC3A from the nucleus as well as their colocalization with DOR, whereas K-to-Q substitutions at the first Lys behaved like wild-type proteins. Taken together, the deacetylation of the second conserved Lys is critical for the cytoplasmic shuttling of GABARAP and LC3A during autophagy, which is in contrast to what was observed with LC3B where deacetylation of both Lys was required. This study also provides insights into interactions between the NSs protein of RVFV and LC3 proteins and the impact of NSs on autophagy during RVFV infection. We identified four potential LIR motifs (NSs1-4) in the NSs protein and ITC studies demonstrated that NSs4 interacts with submicromolar-micromolar affinity with the human LC3 proteins. In addition, we confirmed that LC3 proteins interact with NSs in cells and that in RVFV infected cell LC3A colocalizes with NSs. Taken together, the results indicate that the NSs protein plays a key role in altering autophagy during RVFV infections.

This dissertation looks at the impact of East Coast Fever on African homestead society in Natal in the period 1901-1910. The disease broke out in Natal at the beginning of 1904. With the realization that East Coast Fever was another lethal epizootic, the Natal Colonial Government introduced measures to control the spread of the disease and finally eradicate it. The campaign was, however, not successful. The disease thus spread throughout the colony and led to the loss of many cattle owned by Africans. By 1909 not more than four divisions in the colony remained free of the disease. The death of many cattle deprived Africans of the means of extensive cultivation, the source of income for the payment of rents and taxes, and Ilobolo. Many African males were forced to leave their homesteads for the towns and the mining sector in search of work. This eventually changed the nature of the homestead society. / History / M.A. (History)

Summaries in Afrikaans and English / Op 3 Mei 1848 het 'n aantll blanke nedersetters van Ohrigstad in Soutpansberg aangekom; 'n pioniersdorp, onder Ieiding van Hendrik Potgieter, is gestig en primitiewe huise is opgerig. In 1855 het Stephanus Schoeman die Ieiding oorgeneem en die dorp na homself vemoem. Die plaaslike owerheid het bestaan uit die kommandant-generaal, 'n landdros met heemrade en ander regeringsamptenare sowel as dorpsbeamptes. Tropiese koorssiektes het soms epidemiese afmetings aangcneem en talle mense het gesterf soos die kerkhof met sy rye grafte getuig. Die nedersetters, gehard deur hul swerwersbestaan, het die siektes en ontberings verduur. Vir 16 van die 19 jaar was daar nie 'n vaste predikant nie tot ds N J van Wannelo in 1864 hom in Schoemansdal gevestig het Hy het hom beywer vir die ophefftng van die inwoners op geestelike en onderwysgebied. Die mense was konserwatief en meestal ongeletterd. Hulle was bedagsaam, maar daar was ook ongure en opstandige persone. Hulle klere was eenvoudig en meestal tuisgemaak, en hulle het graag sosiaal verkeer. V erskeie beroepe is beoefen: houtsaery was betalend en hout was oorvloedig; jag was die winsgewendste, want wild en olifante was volop en jagprodukte, veral ivoor waarvan tonne verhandel is, het goeie markpryse behaal. Die swartes wat reeds in die gebied gewoon het, het die blankes met wanttoue bejeen. Blankes het hulle gevestig, grond toegeeien en onbeperk gejag, terwyl die swartes vir hulle moes werk en belasting betaal. Ongehoorsame swart hoofmanne is aangeval, vee is gebuit en vrouens en veral kinders is weggevoer as inboekelinge. Dit het tot openlike vyandelikhede gelei. Veldtogte is gevoer, maar die blankes kon die swartes, weens hulle oninneembare vestings, nie onderwerp nie. Die swartes het gewere op onwettige wyse bekom. Die handel het begin kwyn, smouse en handelaars het weggebly en die inwoners het verann en onder mekaar getwis. Die blankes het in die skans in Schoemansdal saamgetrek en Paul Kruger is met 400 man deur die Transvaalse regering gestuur om die Venda te onderwerp. Die poging het misluk en op 15 Julie 1867 is Schoemansdal ontruim. Enkele maande later is 'n poging deur Schoeman aangewend om die dorp te herwin, maar ook dit was onsuksesvol. Schoemansdal sou nooit weer herbou word nie en was die eerste vesting wat die blankes aan die swart meerdetheid sou oorgee. / May 1848 a number of white settlers from Ohrigstad arrived in the Soutpansberg. Under the leadership of Hendrik Potgieter, a pioneer town was developed. In 1855 Stephan us Schoeman replanned and renamed the town. The local government consisted of the commandantgeneral, a landdrost, heemrade, government officials and town officers. The region was unhealthy and fever stricken. Numerous graves in the graveyard are the tragic signs of many deaths. However, hardy Trekkers, endured the sickness and hardships. For 16 years there was no minister until, in 1864, the Rev Van Warmelo settled in Schoemansdal and worked zealously for the spiritual and educational upliftment of the inhabitants. Most people were conservative and illiterate. Their clothes were plain and usually home-made, and they were very sociable. There were different occupations. Woodcutters were well paid and wood was abundant. Hunting was lucrative because there were plenty of wild animals and elephant, and hunting products, especially ivory, had good market value. Black communities, which already inhabited the area, distrusted the whites. The whites settled, annexed the land and hunted wherever they wanted, while the blacks were compelled to work and pay taxes. Military campaigns were undertaken against headmen who were regarded as disobedient, livestock was seized, women, and children, were abducted under the indenture system. All this caused open hostility. Campaigns were launched against the blacks but they could not be subjected because of the mountainous terrain. The blacks obtained weapons illegally. Trade deteriorated and the whites became poorer and started to quarrel amongst themselves. The white inhabitants moved into the fort and Paul Kruger was sent by the Transvaal government with 400 men to force the Venda into submission. The attempt failed and on 15 July 1867 the town was evacuated. Schoeman, with a small army, also made an unsuccessful attempt. Schoemansdal would never be rebuilt and was the first white settlement to surrender to black majority. / History / D.Litt. et Phil. (Geskiedenis)

In under 6 decades dengue has emerged from South East Asia to become the most widespread arbovirus affecting human populations. Recent dramatic increases in epidemic dengue fever have mainly been attributed to factors such as vector expansion and ongoing ecological, climate and socio-demographic changes. The failure to control the virus in endemic regions and prevent global spread of its mosquito vectors and genetic variants, underlines the urgency to reassess previous research methods, hypotheses and empirical observations. This thesis comprises a set of studies that integrate currently neglected and emerging epidemiological, ecological and evolutionary factors into unified mathematical frameworks, in order to better understand the contemporary population biology of the dengue virus. The observed epidemiological dynamics of dengue are believed to be driven by selective forces emerging from within-host cross-immune reactions during sequential, heterologous infections. However, this hypothesis is mainly supported by modelling approaches that presume all hosts to contribute equally and significantly to the selective effects of cross-immunity both in time and space. In the research presented in this thesis it is shown that the previously proposed effects of cross-immunological reactions are weakened in agent-based modelling approaches, which relax the common deterministic and homogeneous mixing assumptions in host-host and host-pathogen interactions. Crucially, it is shown that within these more detailed models, previously reported universal signatures of dengue's epidemiology and population genetics can be reproduced by demographic and natural stochastic processes alone. While this contrasts with the proposed role of cross-immunity, it presents demographic stochasticity as a parsimonious mechanism that integrates, for the first time, multi-scale features of dengue's population biology. The implications of this research are applicable to many other pathogens, involving challenging new ways of determining the underlying causes of the complex phylodynamics of antigenically diverse pathogens.

Le genre bactérien Salmonella regroupe plus de 2500 sérovars, mais peu sont responsables de pathologies humaines. Salmonella enterica sérovar Typhi (S. Typhi) est reconnu pour son importance médicale à travers le globe. S. Typhi cause la fièvre typhoïde chez l’Homme, une maladie infectieuse létale caractérisée par la dissémination systémique de la bactérie vers des organes du système réticulo-endothélial. La fièvre typhoïde représente un fardeau pour la santé mondiale, notamment auprès des pays en développement où les conditions sanitaires sont désuètes. La situation se complique davantage par l’apparition de souches résistantes aux antibiotiques. De plus, les deux vaccins licenciés sont d’efficacité modérée, présentent certaines contraintes techniques et ne sont pas appropriés pour les jeunes enfants et nourrissons. La phase systémique de l’infection par Salmonella repose sur sa survie dans les macrophages du système immunitaire. Dans ce compartiment intracellulaire, la bactérie module les défenses antimicrobiennes grâce à de multiples facteurs de virulence encodés dans son génome. Les mécanismes moléculaires sollicités sont complexes et finement régulés. Malgré les progrès scientifiques réalisés précédemment, plusieurs incompréhensions persistent au sujet de l’adaptation de ce pathogène dans les macrophages de l’hôte. Pour mieux concevoir les déterminants génétiques de S. Typhi impliqués dans l’interaction avec ces cellules, une stratégie de sélection négative a été appliquée afin de vérifier systématiquement l’effet direct des gènes pendant l’infection. En premier temps, une librairie de mutants par transposon chez S. Typhi a été créée pour l’infection de macrophages humains en culture. Après 24 heures d’infection, la présence des mutants fut évaluée simultanément par analyse sur des biopuces de Salmonella. Au total, 130 gènes ont été sélectionnés pour leur contribution potentielle auprès des macrophages infectés. Ces gènes comptaient des composantes d’enveloppe bactérienne, des éléments fimbriaires, des portions du flagelle, des régulateurs, des facteurs de pathogenèse et plusieurs protéines sans fonction connue. En deuxième temps, cette collection de gènes a dirigé la création de 28 mutants de délétion définie chez S. Typhi. Les capacités d’entrée et de réplication intracellulaire de ces mutants au sein des macrophages humains ont été caractérisées. D’abord, les macrophages ont été co-infectés avec les mutants en présence de la souche sauvage, pour vérifier la compétitivité de chacun d’eux envers cette dernière. Ensuite, les mutants ont été inoculés individuellement chez les macrophages et leur infectivité fut mesurée comparativement à celle de la souche sauvage. Sommairement, 26 mutants ont présenté des défauts lorsqu’en compétition, tandis que 14 mutants se sont montrés défectueux lorsque testés seuls. Par ailleurs, 12 mutants ont exposé une déficience lors de l’infection mixte et individuelle, incluant les mutants acrA, exbDB, flhCD, fliC, gppA, mlc, pgtE, typA, waaQGP, STY1867-68, STY2346 et SPI-4. Notamment, 35 nouveaux phénotypes défectueux d’entrée ou de survie intracellulaire chez Salmonella ont été révélés par cette étude. Les données générées ici offrent plusieurs nouvelles pistes pour élucider comment S. Typhi manipule sa niche intracellulaire, menant à l’infection systémique. Les gènes décrits représentent des cibles potentielles pour atténuer la bactérie chez l’humain et pourraient contribuer au développement de meilleures souches vaccinales pour immuniser contre la fièvre typhoïde. / The bacterial genus Salmonella holds over 2500 serovars, but few are responsible for human pathologies. Salmonella enterica serovar Typhi (S. Typhi) is recognized across the globe for its medical importance. S. Typhi causes typhoid fever in humans, a lethal infectious disease characterized by systemic dissemination of the bacteria to organs of the reticulo-endothelial system. Typhoid fever represents a burden for public health, notably in developing countries where sanitary conditions are obsolete. The situation is further complicated by the appearance of strains resistant to antibiotics. Moreover, both of the licensed vaccines are of moderate efficiency, present certain technical constraints and are not appropriate for young children and newborns. The systemic phase of infection by Salmonella relies on its survival within macrophages of the immune system. In this intracellular compartment, the bacterium modulates antimicrobial defenses thanks to multiple virulence factors encoded within its genome. Molecular mechanisms taking place are complex and finely regulated. Despite scientific advances made previously, many misunderstandings persist concerning the adaptation of this pathogen within host macrophages. To better conceive the genetic determinants of S. Typhi involved in interaction with these cells, a negative selection strategy was applied to systematically verify the direct effect of genes during infection. Firstly, a library of transposon insertion mutants in S. Typhi was created for infection of cultured human macrophages. After 24 hours of infection, the presence of mutants was evaluated simultaneously by analysis on Salmonella microarrays. In total, 130 genes were selected for their potential contribution within infected macrophages. These genes included bacterial envelope components, fimbrial elements, portions of the flagellum, regulators, pathogenesis factors, and many proteins of unknown function. Secondly, this collection of genes led to the creation of 28 defined deletion mutants in S. Typhi. The ability of entry and intracellular replication of these mutants within human macrophages were characterized. To start, macrophages were coinfected with mutants in the presence of the wild-type strain, in order to verify the competitiveness of each of them against the latter. Then, mutants were inoculated individually into macrophages and their infectiveness was measured in comparison with the wild-type strain. In summary, 26 mutants presented defects when in competition, whereas 14 mutants were shown defective when tested alone. Furthermore, 12 mutants exposed a deficiency during mixed and individual infection experiments, including mutants acrA, exbDB, flhCD, fliC, gppA, mlc, pgtE, typA, waaQGP, STY1867-68, STY2346, and SPI-4. In particular, 35 new defective phenotypes of Salmonella entry or intracellular survival were revealed in this study. Data generated here provides significant novel insight for elucidating how S. Typhi manipulates its intracellular niche, leading to systemic infection. Genes described represent potential targets for attenuating the bacteria in the human host and could contribute to the development of better vaccine strains to immunize against typhoid fever.

No description available.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Transtornos psiquiátricos têm sido descritos com maior freqüência em pacientes com Coréia de Sydenham (CS) do que em pacientes com Febre Reumática(FR) sem CS. Os objetivos desse estudo forma o de verificar: se existe uma freqüência aumentada de transtornos psiquiátricos em pacientes com FR comparados a um grupo controle; se estes transtornos psiquiátricos apresentam freqüência aumentada em grupo de pacientes com Coréia de Sydenham, a manifestação da FR no Sistema Nervoso Central, comparado ao grupo de pacientes com FR sem CS; e, por fim, verificar a relação temporal entre o início destes diversos transtornos e o início da FR. Concluiu-se que a presença de FR está associada a uma maior freqüência de transtornos psiquiátricos, mesmo na ausência de CS. O TDHA e o TT, neste estudo, foram indicados como fatores de risco para o desenvolvimento de CS em pacientes com FR. / Psychiatric disorders have been described as more frequent in Sydenham’s Chorea patients SC) than in rheumatic fever without SC (RF). The aim of this study was to investigate it the prevalence of psychiatric disorders in RF is associated with the occurrence of SC. Furthermore, age of onset of the various symptoms was determined in order to clarify the temporal relationship between the presence of psychiatric symptoms and either rheumatic fever or Sydenham’s Chorea. Using semi-structured diagnostic interviews for DSM-IV and ratings scales, the authors assessed 22 SC patients, 20 RF patients and 20 pediatric controls. Statistical Analyses were performed using Pearson chi-square (Fischer’s exact test for 2x2 tables) for comparisons of categorial variables. Comparisons of continuous variables among groups were carried out using ANOVA and the Student t-test, when only groups were analyzed. In order to establish the risk for the development of SC and OCD given to presence of other co-morbid conditions, a logistic regression was applied. The level of significance adopted was 0.05. Both the SC and RF groups showed a greater prevalence of psychiatric disorders. The SC sample showed higher frequency of major depression disorder (MDD) (x2 = 19,1, df = 2, p = 0,00007), tic disorder (TD) (x2 = 21,1, df = 2, p = 0,00001) and attention-deficit hyperactivity disorder (ADHD) (x2-21,7, df = 2, p = 0,0002). Although Obsessive-Compulsive Disorder (OCD) was not statiscally higher in the SC and RF groups, Obsessive-Compulsive Symptoms were more frequent in both RF and SC groups compared to the controls (x2 = 7,3, df = 2, p = 0,025). The age of onset for both ADHD and TD predicted the risk for development of SC. The risk of development of OCD in SC children was also associated with the age of onset of ADHD. RF seems to confer increased risk to develop neuropsychiatric disorders even in patients without SC. In this sample, ADHD and TD was an important risk factor for the occurrence of co-morbid illnesses.

A ablação cirúrgica por radiofreqüência (RF) é uma nova técnica para tratar a fibrilação atrial (FA) permanente. O objetivo deste estudo é avaliar a eficácia da ablação cirúrgica por RF da FA permanente em pacientes com valvopatia mitral reumática (VMR). Entre Fevereiro de 2002 e Abril de 2003, 70 pacientes com FA permanente e VMR foram submetidos à operação da valva mitral associada à ablação por RF da FA (Grupo A); ou à operação da valva mitral isolada (Grupo B). No seguimento pós-operatório foram avaliados: a reversão para o ritmo sinusal (RS) e a contratilidade atrial. Após 12 meses de seguimento, os índices de reversão para o RS e de restabelecimento da contratilidade atrial foram significativamente superiores no Grupo A. A ablação cirúrgica por RF é eficaz para o tratamento da FA permanente em pacientes com VMR / Radiofrequency ablation is a new surgical technique to treat permanent atrial fibrillation. The aim of this study was to evaluate the effectiveness of the (RF) ablation for the treatment of permanent AF in patients with rheumatic mitral valve (MV) disease. Between February 2002 and April 2003, 70 patients with permanent AF and rheumatic MV disease were assigned to undergo a MV surgery associated with RF ablation (Group A), or MV surgery alone (Group B). After 12 months of follow-up, the cumulative rates of sinus rhythm conversion and atrial transport function restoration were higher in Group A.The RF ablation is effective for treating permanent AF associated with rheumatic MV disease