Maize is the staple food for the majority of Tanzanians. However, maize production in the Southern highlands of Tanzania (SHT) is highly reduced by gray leaf spot disease (GLS) caused by the fungus Cercospora zea maydis. GLS reduces grain yield, kernel and silage quality. The most common GLS control methods in Tanzania include amongst others; fungicides, crop rotation, field sanitation, host resistance. These methods except host resistance are, however, either expensive or less effective or unsafe to the environment. Furthermore, conventional breeding strategies are not very effective for traits, which are lowly inherited such as GLS resistance. Lastly, to date there are few GLS resistant commercial hybrids in SHT. Thus, this study aimed to produce more commercial GLS resistant hybrids, increase farmers’ hybrid choices of growing genetically different GLS insensitive hybrids, which will also provide a constant supply of GLS resistant maize cultivars in case of GLS resistance breakdown due to new GLS pathotypes. This research combined conventional breeding with molecular technologies to increase the efficacy of selecting GLS resistant hybrids and assist breeders in predicting best inbred combinations for commercial hybrid production. Studies conducted to meet the main aims were on; the prediction of best line combiners and heterosis in Tanzanian maize breeding lines through the use of amplified fragment length polymorphism, (AFLP), an association of AFLPs and the performance of phenotypic traits in maize, evaluation of maize hybrids for gray leaf spot resistance in multienvironments and finally a preliminary study on gray leaf spot PCR-based marker development with the long term objective of implementing cleaved amplified polymorphic markers (CAPS) in a marker assisted selection (MAS) strategy in the SHT maize breeding programme. Results from the study revealed that pairwise GD (genetic distance) of the lines varied from a GD of 0.13 to 0.5. High coancentry coefficients were exhibited by these lines. Joint data analyses showed that there were tighter associations between line GD and F1 traits or MPH in the intergroup than in the intragroup crosses. Combined analyses revealed that hybrids 48, 90 and 45 recorded higher stable yields and consistently low GLS scores in multienvironments. Fifteen CAPS marker bands were identified that are putatively linked to the GLS resistant genes. In summary, it was noted that strong selection during inbreeding programs should be avoided as it reduces germplasm variability. Local landraces/varieties can be improved by introgressing desirable genes into them. AFLP marker system could be effectively used for inbred genetic diversity studies in Tanzania. Intergroup crosses with high GD-MPH should be the main target for commercial hybrid production but field testing of them is inevitable to confirm their yielding potentials. Intergroups and intragroup crosses with low GD-MPH should be discarded to avoid field costs. Better F1 hybrid performance predictions can be achieved by integrating inbred GD and F1 phenotypic data. Hybrids with low GLS/high GLS resistance could be used to produce other breeding populations. Hybrids 45, 48 and 90 can be commercially preleased. Lastly a study to characterize the GLS fungus in the SHT is imperative since information on virulence of isolates is needed for long term breeding strategies against the fungus. Finally, the SHT maize germplasm has potential GLS resistant inbred lines which could be used in the deployment of genes to susceptible lines and in the development of commercial GLS resistant hybrids/open pollinated varieties/doubled haploid hybrids. / Thesis (PhD)--University of Pretoria, 2008. / Genetics / unrestricted

Introduction: Research has found extensive similarities between symptoms of gaming disorder/Internet gaming disorder (GD/IGD) and symptoms of other addictive disorders, including the presence of cravings, tolerance, and inability to stop despite adverse consequences (Müller & Montag, 2017). Significant associations between GD/IGD and financial strain, occupational difficulties, sleep deprivation, malnutrition, obesity, and the development and/or exacerbation of other mental illness have been found, contributing to growing concern over the detrimental impact of GD/IGD (Kohorst et al., 2018). Video gaming is also associated with increased use of substances, including nicotine as found in electronic nicotine delivery systems (ENDS; Cranwell et al., 2016). The harmful consequences of ENDS use may exacerbate the health risks associated with GD/IGD, especially in connection to sleep, nutrition, and mental health. There is extensive overlap between the demographic and psychosocial characteristics of typical video gamers and typical users of ENDS, including being young, male, highly impulsive, sensation-seeking, and having a diagnosis of attention-deficit hyperactivity disorder (ADHD), which may account for the rates of concurrent dependence (Von der Heiden et al., 2019; Mathews, 2019). However, definitive characteristics of individuals demonstrating symptoms of both GD/IGD and ENDS dependency remain unknown. The present study aims to explore the demographic and psychological associations of co-occurring symptoms of GD/IGD and ENDS dependency. Method:Participants (n = 2,174) were college students age 18-24 (M=19.25) recruited as part of a multi-university study examining psychological variables within young adults. Participants completed a battery of self-report questions assessing for demographic characteristics, symptoms of ADHD, and level of impulsivity and sensation seeking as measured by the Adult ADHD Self-Report Scale, Brief Sensation Seeking Scale, and Barratt Impulsiveness Scale Version 11, respectively. ENDS dependency was evaluated through the PROMIS E-cigarette Dependence Scale, and GD/IGD was measured by the Video Game Dependency Scale. Pearson correlations, chi-square tests, MANCOVAS, and moderation analyses were used to evaluate this data. Results:Results found that 7.3% of the sample met criteria for probable ENDS dependency, 4.7% of the sample endorsed symptoms of GD/IGD dependency, and 1.4% of the sample endorsed both dependencies. Age, gender, and race/ethnicity were all associated with increased risk of concurrent GD/IGD and ENDS dependency. The moderating effect of ADHD symptoms on the relation between GD/IGD and ENDS dependency was significant, ΔR2 = .067, F(1, 1036) = 24.75, p < .001, indicating that the relation between GD/IGD and ENDS dependency was stronger when participants endorsed more symptoms of ADHD. Impulsivity and sensation seeking also had significant interaction effects on the relation between ENDS dependency and GD/IGD. Conclusion:Ultimately, there is ample evidence that ENDS dependency and GD/IGD occur at significant levels on college campuses. Heightened impulsivity and sensation seeking and the diagnosis of ADHD significantly correspond with increased rates of GD/IGD and ENDS dependency. These results are supported by prior research findings that impulsivity and sensation seeking are risk factors for many behavioral health concerns, including engagement in risky sexual behaviors and substance addiction. Future research examining protective factors and treatment of co-occurring GD/IGD and ENDS dependency is warranted. References: Cranwell, J., Whittamore, K., Britton, J., & Leonardi-Bee, J. (2016). Alcohol and tobacco content in UK video games and their association with alcohol and tobacco use among young people. Cyberpsychology, Behavior and Social Networking, 19(7), 426-434. https://doi.org/10.1089/cyber.2016.0093 Kohorst, M. A., Warad, D. M., Nageswara Rao, A. A., & Rodriguez, V. (2018). Obesity, sedentary lifestyle, and video games: The new thrombophilia cocktail in adolescents. Pediatric Blood & Cancer, 65(7), e27041. Mathews, C. L., Morrell, H. E. R., & Molle, J. L. (2019). Video game addiction, ADHD symptomatology, and video game reinforcement. The American Journal of Drug and Alcohol Abuse, 45(1), 67-76. https://doi.org/10.1080/00952990.2018.1472269 Müller, M., & Montag, C. (2017). The relationship between internet addiction and alcohol consumption is influenced by the smoking status in male online video gamers. Clinical Neuropsychiatry: Journal of Treatment Evaluation, 14(1), 34–43. Von der Heiden, J. M., Braun, B., Müller, K. W., & Egloff, B. (2019). The association between video gaming and psychological functioning. Frontiers in Psychology, 10, 17-31. https://doi.org/10.3389/fpsyg.2019.01731

My dissertation research focused on studying mechanisms of immunomodulation by probiotic lactobacilli on innate and T cell immune responses induced by rotavirus infection and vaccines in a gnotobiotic pig model of human rotavirus (HRV) infection and vaccination. We first studied the effects of probiotics on antigen-presenting cells (APCs) through TLR activation. We found that a mixture of Lactobacilli acidophilus strain NCFM (LA) and L. reuteri (ATCC# 23272) induced strong TLR2-expressing APC responses and virulent HRV induced a TLR3 response. Probiotics and HRV had an additive effect on TLR2- and TLR9-expressing APC responses, consistent with the adjuvant effect of lactobacilli. Dose effects of LA on T cell immune responses were investigated. We found that low dose LA significantly enhanced frequencies of HRV-specific IFN-γ producing CD4⁺ and CD8+ T cells whereas high dose LA reduced frequencies of HRV-specific IFN-γ producing CD4+ T cells. Low dose LA reduced frequencies of induced regulatory (iTreg) cells and TGF-β expression in the iTreg cells whereas high dose LA increased frequencies of iTreg cells and IL-10 expression in the iTreg cells. The dose effects of LA were independent of HRV infection/vaccination. In addition, we demonstrated that TCR-γδ T cells play an important role in modulating immune responses to rotavirus infections. All three γδ T cell subsets showed evidence of activation after HRV infection by increasing TLR2, TLR3, TLR9 expression and IFN-γ production during the acute phase of infection. There was an additive effect between lactobacilli and HRV in inducing total γδ T cell expansion in ileum and in recruiting the cells from blood. HRV infection induced a significant expansion of the CD2+CD8+ γδ T cell subset in the ileum. This subset mainly exerts regulatory functions as evident by expressing FoxP3, secreting TGF-β and IL-10 or increasing production of the anti-inflammatory cytokines by CD4+ and/or CD8+ αβ T cells in the co-cultures. CD2+CD8- and CD2-CD8- γδ T cell subsets have mainly pro-inflammatory and anti-viral functions as evident by secreting IFN-γ or promoting CD4+ αβ T cell proliferation and IFN-γ production. This knowledge will facilitate the development of more effective vaccination and therapeutic strategies to protect children and young animals against rotavirus gastroenteritis. / Ph. D.

The studies presented here evaluate the biliary, parenchymal and vascular enhancement effects of two T1-shortening liver-specific contrast agents, Gd-BOPTA and Gd-EOB-DTPA, in Magnetic Resonance Imaging (MRI) of healthy subjects and of patients. Ten healthy volunteers were examined with both contrast agents in a 1.5 T MRI system using three-dimensional gradient echo sequences for dynamic imaging until five hours after injection. The enhancement of the common hepatic duct in contrast to the liver parenchyma was analyzed in the first study. This was followed by a study of the image contrasts of the hepatic artery, portal vein and middle hepatic vein versus the liver parenchyma. While Gd-EOB-DTPA gave an earlier and more prolonged enhancement and image contrast of the bile duct, Gd-BOPTA achieved higher maximal enhancement and higher image contrast for all vessels studied during the arterial and portal venous phases. There was no significant difference in the maximal enhancement obtained in the liver parenchyma. In a third study, another 10 healthy volunteers were examined with the same protocol in another 1.5 T MRI system. Using signal normalization and a more quantitative, pharmacokinetic analysis, the hepatocyte-specific uptake of Gd-EOB-DTPA and Gd-BOPTA was calculated. A significant between-subjects correlation of the uptake estimates was found and the ratio of these uptake rates was of the same magnitude as has been reported in pre-clinical studies. The procedure also enabled quantitative analysis of vascular enhancement properties of these agents. Gd-BOPTA was found to give higher vessel-to-liver contrast than Gd-EOB-DTPA when recommended doses were given. In the final study, retrospectively gathered datasets from patients with hepatobiliary disease were analyzed using the quantitative estimation of hepatic uptake of Gd-EOB-DTPA described in the third study. The uptake rate estimate provided significant predictive ability in separating normal from disturbed hepatobiliary function, which is promising for future evaluations of regional and global liver disease. In conclusion, the differing dynamic enhancement profiles of the liver-specific contrast agents presented here can be beneficial in one context and challenging in another. Diseases of the liver and biliary system may affect the vasculature, parenchyma or biliary excretion, or a combination of these. The clinical context in terms of the relative importance of vascular, hepatic parenchymal and biliary processes should therefore determine the contrast agent for each patient and examination. A quantitative approach to analysis of contrast-enhanced liver MRI examinations is feasible and may prove valuable for their interpretation.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Bovine herpesviruses 1 (BoHV-1) and 5 (BoHV-5) are genetic and antigenic closely related pathogens of cattle, historically associated with respiratory/genital and neurological disease, respectively. This thesis reports the genomic and phylogenetic analyzes based on glycoproteins C (gC) and D (gD) genes of BoHV-1 and BoHV-5. Initially, the differentiation between BoHV-1 and BoHV-5 was performed by a differential PCR based on 5 gC gene. Then, a molecular analysis based on the 3 region of the gC gene of 45 BoHV isolates from Brazil, Uruguay and Argentina (1981-2009) was described. The phylogenetic tree reconstruction provided a clear distinction between BoHV-1 and BoHV-5, and BoHV-1 into subtypes BoHV-1.1 and BoHV-1.2. The levels of nucleotide (nt) similarity ranged from 99.1 to 100% among BoHV-1 sequences (n=12); 96.2-100% among BoHV-5 sequences (n=32); and 77.7-90.3% between BoHV-1 and BoHV-5 sequences. A transmembrane domain of 24 amino-acid (aa) and the putative cytoplasmic tail of 8 aa were also identified. In addition, a phylogenetic study was performed to investigate genetic divergences at the 3 region of gD gene of respiratory/genital BoHV-1 (n=7), neurological BoHV-1 (n=7) and neurological BoHV-5 (n=7) isolates, and whether these differences would be associated with the respective neurological presentation. The phylogenetic reconstruction allowed a clear differentiation of BoHV-1 (n=14) and BoHV-5 (n=7), but BoHV-1 isolates from neurological disease grouped within BoHV-1 branch. The nt and aa similarity levels were on average 98.3% among BoHV-1; 97.8% and 95.8% among BoHV-5; 73.7% and 64.1% between viral species. These results indicate that both genes revealed a high conserved 3 region within each species and a less conserved region between BoHV-1 and BoHV-5. The phylogenetic analyzes allowed differentiation of BoHV-1 and BoHV-5 species, and even subtypes grouped in distinct branches in the 3 gC gene-based study, indicating that this region represents a better choice for phylogenetic subgrouping. So, it was concluded that these genome regions represent a suitable target for phylogenetic classification of BoHV-1 and BoHV-5 isolates, and, perhaps, for understanding evolutionary relationships. However, no conclusion of a possible association of genetic differences with phenotypes could be drawn. / Bovine herpesviruses 1 (BoHV-1) and 5 (BoHV-5) are genetic and antigenic closely related pathogens of cattle, historically associated with respiratory/genital and neurological disease, respectively. This thesis reports the genomic and phylogenetic analyzes based on glycoproteins C (gC) and D (gD) genes of BoHV-1 and BoHV-5. Initially, the differentiation between BoHV-1 and BoHV-5 was performed by a differential PCR based on 5 gC gene. Then, a molecular analysis based on the 3 region of the gC gene of 45 BoHV isolates from Brazil, Uruguay and Argentina (1981-2009) was described. The phylogenetic tree reconstruction provided a clear distinction between BoHV-1 and BoHV-5, and BoHV-1 into subtypes BoHV-1.1 and BoHV-1.2. The levels of nucleotide (nt) similarity ranged from 99.1 to 100% among BoHV-1 sequences (n=12); 96.2-100% among BoHV-5 sequences (n=32); and 77.7-90.3% between BoHV-1 and BoHV-5 sequences. A transmembrane domain of 24 amino-acid (aa) and the putative cytoplasmic tail of 8 aa were also identified. In addition, a phylogenetic study was performed to investigate genetic divergences at the 3 region of gD gene of respiratory/genital BoHV-1 (n=7), neurological BoHV-1 (n=7) and neurological BoHV-5 (n=7) isolates, and whether these differences would be associated with the respective neurological presentation. The phylogenetic reconstruction allowed a clear differentiation of BoHV-1 (n=14) and BoHV-5 (n=7), but BoHV-1 isolates from neurological disease grouped within BoHV-1 branch. The nt and aa similarity levels were on average 98.3% among BoHV-1; 97.8% and 95.8% among BoHV-5; 73.7% and 64.1% between viral species. These results indicate that both genes revealed a high conserved 3 region within each species and a less conserved region between BoHV-1 and BoHV-5. The phylogenetic analyzes allowed differentiation of BoHV-1 and BoHV-5 species, and even subtypes grouped in distinct branches in the 3 gC gene-based study, indicating that this region represents a better choice for phylogenetic subgrouping. So, it was concluded that these genome regions represent a suitable target for phylogenetic classification of BoHV-1 and BoHV-5 isolates, and, perhaps, for understanding evolutionary relationships. However, no conclusion of a possible association of genetic differences with phenotypes could be drawn.

O câncer cervical é considerado um grande problema de saúde pública e um dos maiores causadores de mortes relacionadas a tumores em mulheres. O principal objetivo desta tese foi aumentar a eficácia antitumoral terapêutica da proteína gDE7 por meio da associação de adjuvantes vacinais em formulações testadas em condições experimentais com a linhagem celular tumoral TC-1. A proteína gDE7 foi produzida a partir de uma linhagem de E. coli e associada a diferentes adjuvantes. A proteína gDE7 coadministrada ao poly(I:C) conferiu proteção antitumoral completa aos camundongos previamente desafiados e induziu ativação de linfócitos T CD8+ E7-específicos polifuncionais, citotóxicos e de fenótipo de memória efetora/efetor. Foi demonstrado que a proteína gDE7 ativa de forma específica a subpopulação de células dendríticas especializada na apresentação cruzada de antígenos para linfócitos T CD8+, tanto em camundongos como em seres humanos. Esses resultados abrem perspectivas para o emprego da proteína gD como plataforma vacinal para o controle de tumores induzidos pelo HPV-16. / Cervical cancer is considered a major public health problem and one of the leading causes of cancer death in women. The main goal of this thesis was the improvement of a therapeutic antitumor vaccine based on gDE7 protein in formulations admixed with adjuvants under experimental conditions with the tumor cell line TC-1. The gDE7 protein was expressed and purified from E. coli, and then tested in combination with different vaccine adjuvants. The gDE7 protein admixed with poly(I:C) conferred complete therapeutic antitumor protection to mice previously challenged with TC-1 cells and induced polyfunctional, cytotoxic E7-specific CD8+ T cells with effector/effector memory phenotype. It was also demonstrated that the gDE7 protein activated a specialized dendritic cell subset involved in specific antigen cross-presentation to CD8+ T cells, both in mice and humans. These results open perspectives for the use of the gD protein use as a vaccine platform for the control of HPV-16-induced tumors.

O câncer cervical é considerado um grande problema de saúde pública e um dos maiores causadores de mortes relacionadas a tumores em mulheres. O principal objetivo desta tese foi aumentar a eficácia antitumoral terapêutica da proteína gDE7 por meio da associação de adjuvantes vacinais em formulações testadas em condições experimentais com a linhagem celular tumoral TC-1. A proteína gDE7 foi produzida a partir de uma linhagem de E. coli e associada a diferentes adjuvantes. A proteína gDE7 coadministrada ao poly(I:C) conferiu proteção antitumoral completa aos camundongos previamente desafiados e induziu ativação de linfócitos T CD8+ E7-específicos polifuncionais, citotóxicos e de fenótipo de memória efetora/efetor. Foi demonstrado que a proteína gDE7 ativa de forma específica a subpopulação de células dendríticas especializada na apresentação cruzada de antígenos para linfócitos T CD8+, tanto em camundongos como em seres humanos. Esses resultados abrem perspectivas para o emprego da proteína gD como plataforma vacinal para o controle de tumores induzidos pelo HPV-16. / Cervical cancer is considered a major public health problem and one of the leading causes of cancer death in women. The main goal of this thesis was the improvement of a therapeutic antitumor vaccine based on gDE7 protein in formulations admixed with adjuvants under experimental conditions with the tumor cell line TC-1. The gDE7 protein was expressed and purified from E. coli, and then tested in combination with different vaccine adjuvants. The gDE7 protein admixed with poly(I:C) conferred complete therapeutic antitumor protection to mice previously challenged with TC-1 cells and induced polyfunctional, cytotoxic E7-specific CD8+ T cells with effector/effector memory phenotype. It was also demonstrated that the gDE7 protein activated a specialized dendritic cell subset involved in specific antigen cross-presentation to CD8+ T cells, both in mice and humans. These results open perspectives for the use of the gD protein use as a vaccine platform for the control of HPV-16-induced tumors.

Résumé : En dépit des nombreuses recherches pour réduire le coût d'inspection des pièces à l'aide d'outils numériques, l'inspection de pièces souples demeure un défi. La raison est que les pièces souples peuvent prendre à l'état libre une forme substantiellement différente de leur géométrie nominale. Il en résulte que l'inspection de ce type de pièces nécessite des outils dédiés et coûteux, comme un gabarit d'inspection. Cette thèse détaille les défis associés au contrôle de ces pièces, pour proposer ensuite une méthode permettant l'inspection à l'état libre de pièces souples ayant une spécification limitant les forces de montage. L'approche proposée combine la méthode par éléments finis, les méthodes de traitement d'images ainsi que les démarches du domaine de l'optimisation. Essentiellement, la méthode proposée transpose (maps) le nuage de points représentant la pièce à l'état libre dans une configuration correspondant à sa géométrie installée sur son gabarit d'inspection. La méthode n'exige pas la conversion du nuage de points en modèle d'éléments finis, et veille à ce que les forces de montage ne dépassent pas leurs limites spécifiées, tout en tolérant des incertitudes dans la position des points de fixation simulant l'interface de montage. Ceci est accompli par le biais d'une optimisation par contrainte des déplacements des points de fixation. La contrainte de l'optimisation limite l'étendue des valeurs des forces de montage. La performance de la méthode d'inspection numérique proposée est évaluée à partir de cas d'études simulés, ainsi qu'à partir de deux pièces réelles du secteur de l'aéronautique. // Abstract : Despite extensive research to reduce the cost of inspection of parts using computational tools, inspection of compliant parts remains a challenge. The reason is that in a free-state, compliant parts can take on different shapes compared to their design model. It follows that the inspection of such parts requires dedicated and expensive inspectionfixtures. This thesis details the challenges associated with the inspection of these partsto then propose a fixetureless inspection method for compliant parts for which theirfunctional requirements mandate to limit the restraining forces imposed during assembly. The proposed approach combines the finite element method, image processing andoptimization techniques. Essentially, the proposed method maps the point cloud, representing the part in a free-state, to a configuration corresponding to its shape mounted onto its inspection fixture. The method does not necessitate the conversion of the point cloud into a finite element model, ensures that restraining forces do not exceed their specified limits, and accepts uncertainties in the position of features simulating the mounting interface. This is done through an constrained optimization on the displacements of the fixing points. The optimization constraint bounds the restraining forces values. The performance of the proposed computational inspection method is evaluated on simulated case studies, as well as on two aeronautics workpiece.

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

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