No description available.

In this study the basal expression of Tis 11 family and their regulation in B-CLL cells in response to stimuli that induce apoptosis (crosslinked Rituximab, XRituximab) or stimuli that inhibit spontatieous apoptosis' (IL-4, CD40, CD40+IL-4, PMA) was tested. Tis 11 family bind to AU Rich Elements (AREs) in the 3' Untranslated Region (3'UTR) and induce degradation of mRNAs bearing these target sequences. The Tis 11 family consists of Tis 11, 'Tis 11 b and Tis 11 d which induce apoptosis when overexpressed in a variety of human cell lines (epithelial, osteosarcoma and fibroblasts). It was found that Tis 11 mRNA is strongly expressed in unstimulated B-CLL cells, when compared to Tis 11 b mRNA levels, and was downregulated following stimulation with IL-4 or anti-CD40 at 3 hours post stimulation but remained unaffected by all other stimuli. Tis1l b mRNA was found to be minimally expressed in unstimulated B-CLL cells and was strongly induced following XRituximab, PMA and anti-CD40 treatment in all patients tested but remained unchanged by IL-4 or anti-CD40+IL-4. Finally Tislid was found to be strongly expressed in unstimulated B-CLL cells and was weakly induced by XRituximab and PMA in some but not all patients tested and showed no change after IL-4, anti-CD40 or anti-CD40+IL-4 stimulation. Additionally it was found that when Tis 11 b is induced by XRituximab it is primarily regulated through p38 and to lesser extend through JNK pathway since inhibition of these pathways abrogated induction of the Tis 11 b mRNA and protein. On the contrary when Tis 11b was induced by PMA or anti-CD40 it was found to be regulated through NF-KB pathway since inhibition of this pathway resulted in complete abrogation of Tis11 b mRNA induction following PMA or anti-CD40 stimulation. In order to determine the function that Tis 11 b is involved in reponse to XRituximab and PMA or anti-CD40 treatment, Tisllb siRNA technology was utilised which revealed that inhibition of Tis 11 b significantly reduced (by 50-70%) the efficiency of XRituximab in inducing apoptosis in CLL cells while when Tis 11 b siRNA was applied in PMA or anti-CD40 stimulated CLL cells it significantly reduced their ability to induce plasma cell differentiation in these cells. Thus Tis 11 b is involved in induction of apoptosis following Rituximab treatment in CLL cells and also it is involved in induction of differentiation of CLL cells when such a stimulus (eg: anti-CD40) is present. Finally it was found that Tis 11 bIBerg36 is probably involved in B cell differentiation in general, since it was found that it has different basal expression and regulation at different stages of B cell differentiation represented by Nalm6 (pre-B cells), Ramos (Germinal Centre B cells), AGLeL and WILeL (memory B cells) and RPMI8226 and MM1.S (plasma cells) cell lines. Indeed it was found that Multiple Myeloma cell lines have undetectable levels of Tis 11 bIBerg36 mRNA and neither PMA nor anti-eD40 could induce Tis 11 b in plasma cells even though these stimuli could modify expression of this gene in all other stages of differentiation. Thus Tis 11 family especially Tis 11 b and Tis 11 may have an important role in the pathogenesis or progression of eLL (and possibly of B cell malignancies in general) and necessitate further investigation.

In recent years, a new threat to barley crops has emerged and gained substantial attention due to its rising economic importance. Relatively little is known about the infection strategy and development of Ramularia leaf spot (RLS) disease on barley. Therefore the overall aim of this project was to increase the understanding of fundamental biology and life cycle of the causal agent, R. collo-cygni. Chapter 2 describes the horizontal transmission of the fungus on barley. Both field and transgenic R. collo-cygni isolates expressing GFP and dsRed fluorescent reporter markers were utilised to visualise the infection progression in living host tissues by various light and confocal microscopy. The existence of a previously unknown structure called stomatopodium (infection peg), involved in the penetration of stomata, was demonstrated. The fungus initially exhibited symptomless epiphytic growth, extending above epidermis and connecting the hyphal aggregates inside substomatal cavities and subsequent initial sporulation. However, during the transition into symptomatic phase, the organised intercellular growth of hyphae into the mesophyll was observed. This hyphal network was involved in the production of asexual spores demonstrating that the raprture of epidermal layer was responsible for local necrosis observed for RLS. In addition to barley, several other speculated R. collo-cygni hosts have been used to verify their compatibility to the pathogen. In chapter 3, a whole plant inoculation assay was developed to investigate the mode of the fungal seed-borne transmission by using GFP expressing strain of the fungus. It is shown here for the first time that the vertical transmission is systemic, involving symptomless colonisation of embryo and closely resembled the mode of dissemination observed for Neotyphodium species, mutualistic fungal endosymbionts on grasses. The impact of fungal infection on seed germination ability was also examined that revealed no significant difference between clean, moderate and high levels of R. collo-cygni DNA. Chapter 4 represents an attempt to discover and analyse the sexual development in R. collo-cygni. As a first step to understand the sexual reproduction cycle in this apparently asexual species, the genetic structure of the mating system was characterised by using PCR-based techniques which demonstrated the heterothallic nature of the fungus. The defined population of R. collo-cygni field isolates was then screened for the presence of the discovered mating type idiomorphs (mat) to determine the frequencies of the mating types in the defined R. collo-cygni populations. The segregation ratio of mat1 and mat2 close to 1:1 indicated a frequent sexual reproduction. In order to verify the existence of functional sexual stage in R. collo-cygni, potential sexual development was induced using the potentially compatible isolates and a comprehensive analysis was undertaken by correlative use of light-, confocal- and low temperature scanning electron microscopy. Two types of multicellular bodies were observed and described. First was the speculated Asteromella stage (male donor) that carries spore-like spermatia. The second structure initially resembled sclerotia that in only a few instances developed into perythecium/ pseudothecium that appeared to carry the sexual spores, ascospores enveloped in asci. Chapter 5 demonstrates the role of rubellin toxin in symptom development by using autofluorescence phenomenon. The structure of putative molecular machinery involved in rubellin biosynthesis was addressed by using bioinformatics approaches and the complete R. collo-cygni genome sequence. A gene cluster encompassing several components of other known secondary metabolite biosynthesis pathways, such as that of dothistromin and aflatoxin, was found and putative protein function of the genes is hypothesised.

L’infection par le virus de la grippe, ou le Myxovirus influenzae de type A (IAV), constitue l'une des causes les plus importantes de maladies des voies respiratoires dans le monde. Elle conduit également à des épidémies récurrentes avec des taux élevés de morbidité et de mortalité. Des surinfections bactériennes, principalement causées par Streptococcus pneumoniae (pneumonie), sont souvent associées à la grippe et contribuent de manière significative à l’excès de mortalité. La perturbation de l'intégrité des tissus pulmonaires et la diminution de l'immunité antibactérienne au cours de l'infection par IAV sont à l’origine de la colonisation et à la dissémination des bactéries.L'infection grippale entraîne une altération profonde du compartiment de cellules myéloïdes pulmonaires caractérisée par une altération numérique ou fonctionnelle des cellules sentinelles - les macrophages alvéolaires et les cellules dendritiques conventionnelles (cDC) - et par un recrutement de cellules myéloïdes inflammatoires -les neutrophiles, les monocytes inflammatoires ou encore les cellules dendritiques inflammatoires.Les cellules myéloïdes sont originaires de la moelle osseuse (MO). Lors d’infections, la myélopoïèse peut être profondément affectée afin de maintenir la production et la mobilisation de cellules myéloïdes inflammatoires au niveau du site d’infection. A l’heure actuelle, les conséquences de l’infection grippale sur la myélopoïèse restent encore mal connues.Dans notre projet, nous rapportons que l'infection grippale conduit à une diminution transitoire du nombre de cDC (cDC1 et cDC2) dans les poumons qui coïncide avec une chute dans la MO, du nombre de progéniteurs/précurseurs impliqués dans la génération des cDC (CDP, pre-cDC et plus particulièrement les pre-cDC1). Cette diminution de la "DCpoïèse" est associée à une accélération de la génération des monocytes, i.e. monopoïèse. La différenciation altérée des cDC est indépendante des cytokines pro-inflammatoires et n'est pas due à un dysfonctionnement intrinsèque des précurseurs de cDC. De façon intéressante, nous rapportons que ces altérations au niveau de la MO sont associées à une diminution de la production de Flt3-L ou Fms-like tyrosine kinase 3 ligand, un facteur crucial pour la différenciation des DC. La supplémentation en Flt3-L au cours de la grippe rétablit la différenciation des progéniteurs de cDC dans la MO et restaure le compartiment des cDC pulmonaires. De façon intéressante, cette restauration s’accompagne d’une protection partielle contre l’infection pneumococcique secondaire caractérisée par une réduction de la charge bactérienne, une amélioration de la pathologie pulmonaire et une survie prolongée. / Influenza type A virus (IAV) infection, is one of the most important causes of respiratory diseases worldwide. It also leads to recurrent epidemics with high rates of morbidity and mortality. Secondary bacterial infections, mainly caused by Streptococcus pneumoniae (pneumonia), are often associated with influenza and contribute significantly to excess mortality. Disruption of lung tissue integrity and impaired antibacterial immunity during IAV infection participate in bacterial pulmonary colonization and dissemination out of the lungs.Influenza infection leads to a profound alteration in the pulmonary myeloid cell compartment characterized by numeric or functional alteration of sentinel cells (alveolar macrophages and conventional dendritic cells (cDC)) and recruitment of inflammatory myeloid cells (neutrophils, inflammatory monocytes and inflammatory dendritic cells).Myeloid cells originate from the bone marrow (BM). During infections, myelopoiesis may be profoundly affected in order to maintain the production and mobilization of inflammatory myeloid cells to the site of infection. At present, the consequences of influenza infection on myelopoiesis remain poorly understood.In our project, we report that influenza infection leads to a transient decrease in the number of Cdc (cDC1 and cDC2) in the lungs, and severely impairs the number of BM progenitors committed to the DC lineage (CDP, pre-cDC and, most importantly, the cDC1-biased pre-DC lineage). This reduction was associated with an increase in the production of monocytes in the BM (monopoiesis). The altered cDC differentiation was independent of pro-inflammatory cytokines and was not due to an intrinsic dysfunction of cDC precursors. Defective DC genesis during influenza was associated with a decrease in the production of the key cDC differentiation factor, Fms-like tyrosine kinase 3 ligand (Flt3-L). Importantly, Flt3-L overexpression during influenza restores the differentiation of BM progenitors into cDC - a phenomenon associated with repopulation of cDC in the lungs. The restoration of pulmonary cDC associates with a partial protection against secondary pneumococcal infection characterized by reduced bacterial loads, improved pathological outcomes and prolonged survival.

The most important risk factor for developing a catheter-associated urinary tract infection (CAUTI) is the prolonged use of the urinary catheter. To address the CAUTI rate at the project site, which was higher than the national benchmark, a team of healthcare practice leaders developed an evidence-based algorithm addressing the appropriate indications for inserting or discontinuing a patient's Foley catheter. Using the plan-do-study-act model, the purpose of this quality improvement evaluation project was to evaluate the effectiveness of the evidence-based Foley algorithm for decreasing the use of Foley catheters and reducing the CAUTI rate and to explore whether using the Foley algorithm shift assessment tool would reduce the incidence of Foley catheter utilization. Data were compared on the rate of CAUTI and Foley catheter use over 4 months before and 4 months after implementation of the algorithm. There was a statistically significant decrease in the Foley utilization rate after implementing the Foley algorithm; the overall CAUTI rate did not decrease. The outcome of this quality improvement evaluation project could produce social change by highlighting the need for consistent application of the algorithm. In addition, reducing the rate of Foley catheter usage could decrease the incidence of CAUTIs, reduce hospital costs, and improve overall patient health during hospitalization.

Thesis (MSc (Clinical Psychology)) -- University of Limpopo, 2012. / The aim of the study is to investigate the HIV and Aids knowledge, attitudes, behaviour and beliefs of University of Limpopo undergraduate students (Medunsa Campus) registered for modules in psychology. South African tertiary institutions have a high rate of HIV infection. Empirical evidence indicates that generally male students have multiple partners during their years at university. Various studies reveal that the use of condoms is relatively low amongst students. This investigation utilized a quasi-experimental survey design as it was deemed an appropriate method with which to answer the research question. The questions used in the survey were underpinned by the Health Belief Model (HBM) and the Protection Motivation Theory (PMT). Several open-ended questions were added to lend a qualitative aspect to the study. Proportionate stratified sampling was used. Using this method a sample of students was randomly allocated in each educational level (first year, second year and third year) according to the true proportional number of students in each level. Quantitative data was analyses using descriptive statistics and an independent t-test to look for differences between the means of the male and female groups. Results underpinned other research in this arena For instance, the majority of participants indicated that they know that using a male condom or female condom can prevent the spread of Aids. This suggests that this percentage would take the positive health related action of using a condom. However, fifty one respondents (35.66%) indicated that they were very likely to believe that they would feel uncomfortable buying condoms and forty five respondents (31%) were likely to believe that they would feel uncomfortable buying condoms. This indicates that knowledge is not a good predictor of a positive health related action. Quantitative and qualitative results suggest that stigmatizations and racism exist in the samples attitudes towards aspect of HIV and Aids. The only significant result between the means of the two groups suggests that males are more likely to indulge in high risk sexual behaviours than females.

Thesis (MPH) -- University of Limpopo, 2012. / Background: The HIV pandemic continues to be a major public health problem in Sub-Saharan Africa where 22.5 million people were infected with HIV in 2009 and South Africa remains one amongst the countries with the highest HIV epidemic. The number of HIV-positive and AIDS patients is increasing annually and there are no specialised oral health institutions that provide oral health care to HIV/AIDS patients. HIV and AIDS continues to have profound impact on all health training and education (Medical, Dentistry, Nursing etc.) and clinical care, hence it is crucial for all the health care students to be educated about HIV/AIDS disease. Dental student’s knowledge about HIV/AIDS, attitudes towards HIV-positive patients and infection control practices are of importance as they are the future oral health care providers. The Purpose: The purpose of the study was to determine the knowledge, attitudes and practices of third, fourth and fifth year dental students on HIV-positive and AIDS patients at the Medunsa Oral Health Centre (MOHC). Materials and Methods: This was a cross-sectional study conducted among 139 dental students at MOHC using a self administered questionaire with 30 closedended questions. T-test, one-way Anova (analysis of variance), multiple regressions and Pearson’s correlation were applied by Stata IC/10 to assess, determine and describe the knowledge, attitude and infection control practices of third, fourth and fifth year dental students, respectively and also find an association between demographic variables, knowledge, attitudes and practices. Results: The response rate was 86% (120/139), 33 of third year, 47 of fourth year and 40 of fifth year dental students. Gender was statistically significant towards knowledge and females were more knowledgeable about HIV/AIDS as compared to males (p=0.058). However, almost (98.3%) all dental students were not sure “HIV increases other infections, including oral infections as well”. More than half (53.1%) of third year dental students were not sure “persistent generalised lymphadenopathy vi is associated with stage 2 of HIV infection”. In this study, ethnic groups and level of study (BDS4 & BDS5) were found to be significant predictors of attitude regarding HIV-positive patients (p=0.001) (p=0.055) (p=0.001). Practice was found to be a significant predictor of knowledge regarding HIV/AIDS (p=0.046). Pearson’s correlation coefficient showed students with positive attitude scores had significantly excellent practice regarding HIV/AIDS (r=0.2912) (p=0.001). Good knowledge translates into excellent infection control practices, whilst positive attitude towards HIV/AIDS patients yield excellent infection control practices. Conclusion: The dental students at MOHC relatively have a good understanding of HIV/AIDS (particularly the mode of transmission) but to lesser extent, disease progress and oral manifestation. The lack of knowledge on HIV/AIDS and inconsistency regarding certain infection control procedures may be a reflection of insufficient HIV/AIDS teaching and clinical supervision of students in the wards. There is a need to improve the current dental curriculum by including HIV/AIDS module and incorporate a clinical component of dental screening at the ARV clinics.

Stagonospora nodorum is a necrotrophic fungal pathogen, and the causal agent of stagonospora nodorum blotch of wheat. Despite the economic importance of this disease, the molecular basis of the pathosystem is poorly understood. The aim of this study was to investigate the interaction between metabolism and infection in this pathosystem, with particular reference to the metabolism of mannitol. In common with many fungi, the main metabolite produced by S. nodorum is the acyclic hexitol mannitol. Among the previously suggested roles for this compound is a role in pathogenicity. The metabolism of mannitol has been hypothesised as occurring in a cycle involving the enzymes mannitol 2-dehydrogenase (Mdh1) and mannitol 1-phosphate 5 dehydrogenase (Mpd1). A strain was created harbouring disruption constructs for both of these genes. The double mutant was unable to synthesise or catabolise mannitol, and was unable to sporulate. Addition of exogenous mannitol completely restored in vitro sporulation, and partially restored in planta sporulation. This demonstrated an essential role for mannitol in asexual sporulation. This is the first demonstrated role for this compound. A 13C NMR study of the wild type strain, the mdh1 and mpd1 single mutants, and mpd1mdh1 double mutant was undertaken to investigate carbon utilisation and cycling. Disruption of Mpd1 significantly altered the metabolite profile with the mpd1 mutants producing trehalose and glycerol in place of mannitol. Labelling patterns in the double mutant showed that scrambling of label can be explained by the triosephosphate isomerase triangle and pentose phosphate pathway. This suggests the contribution of mannitol to label scrambling has been overstated in previous studies. The evidence did not support the metabolism of mannitol in S. nodorum as occurring in a cycle, but rather as two separate pathways. A GC-MS analysis of diseased and non-diseased tissue from infected leaves, compared to non-infected and mock-inoculated leaves, could not detect any metabolites associated with a systemic host reaction to pathogen attack.

Orthokeratology (OK) is a specialty contact lens procedure that involves the overnight wear of lenses to reshape the corneal tissue resulting in clear vision upon lens removal. Currently it is the only way of achieving clear vision without having to wear spectacles or contact lenses during the day or undergoing refractive surgery. This thesis investigated the effects of this procedure on the corneal epithelium and the potential increase in risk of microbial infection in an animal model. The cat was first established as an appropriate animal model in a pilot study to examine OK epithelial changes. Initial findings of epithelial thickness changes similar to those found with human myopic and hyperopic OK clinical studies led to the further development of this animal model to better mimic human lens wear for the remaining studies undertaken. Histological studies were used to examine epithelial effects of overnight myopic OK lens wear. Repeatable and differential effects on epithelial thickness and morphology across the cornea were found, including thinning of the central and peripheral epithelium and thickening of the mid-peripheral epithelium. Central thinning was attributed to compression of cells and was less in overnight wear compared to continuous wear. Mid-peripheral thickening was due to increased cell layers and peripheral thinning was attributed to cellular compression. Recovery of epithelial morphologic and thickness changes commenced one day after ceasing lens wear and was complete within one week. Minimal changes to keratocyte populations in regions adjacent to epithelial thickness changes were found. Microbiological studies investigated the effect of epithelial changes on corneal susceptibility to bacterial infections by exposing OK-treated corneas to large amounts of Pseudomonas aeruginosa. The hypothesis that OK lenses increased susceptibility to infection (within the time tested) was rejected as no infections were produced in any animals (except the positive scratch control). Length of OK treatment, duration and quantity of bacterial exposure, lens wearing schedule and bacterial strain type did not affect susceptibility to infection. The epithelium is a major contributor to OK-induced corneal changes. These epithelial changes are reversible and do not appear to predispose to infection provided corneal integrity is maintained.

Thesis (M.Dip.)--Cape Technikon, 1988. / Typescript (photocopy) Bibliography: leaf 117-148. Also available online.