Aflatoxin B1 and T-2 toxin are mycotoxins, which produce their immunotoxic effects by affecting nonspecific and acquired immunity in different species. The mechanisms of their immunotoxicity are still obscure. Cytokines are the key signaling molecules during the immune response. In this study, expression of macrophage-produced cytokines Interleukin-lα (IL-lα), tumor necrosis factor (TNF), and IL-6, and lymphocyte-produced cytokines IL-2, interferon y (IFNy), and IL-3 was measured at the mRNA and protein levels, after in vitro activation with mitogens in AFB1-and T-2-toxin-exposed mice. Significant changes in the organ weights, especially in the mice exposed to a high dose of T-2 toxin, and no effect in AFB1-exposed mice were observed. ConA-induced production of IL-2, IFNy, and IL-3 mRNA and protein levels in AFB1-exposed mice showed a decrease in low dose groups (significant for IL-2 mRNA), but no change at other doses. However, in T-2-toxin-treated animals, there was a significant induction of IL-2 and IFNy mRNA in high and low doses and of IL-3 mRNA at the medium dose. The protein levels of IL-2 and IFNy did not follow the mRNA levels in high dose and the protein levels of IL-3 were significantly increased in medium and low doses. LPS-induced IL-lα and TNF mRNA and protein levels in AFB1-exposed mice were suppressed at the high dose while mRNA levels of both cytokines were increased significantly in the low and medium doses. Low and medium doses of AFB1 also significantly decreased IL-lα protein levels and the high dose decreased IL-6 protein. In T-2 toxin-treated mice, no significant difference in mRNA levels of these cytokines was observed but a general pattern of significant suppression of their protein levels (except IL-lα at medium dose) showed that both toxins regulate the cytokine expression differently. Based on the above discussed results and others, AFB1 may alter cell-mediated immunity by affecting the communication between macrophages and T lymphocytes through inhibiting the macrophage-producing cytokines. T-2 toxin-induced immunosuppression may be due not only to the inhibition of macrophage-producing cytokines, but also to the lack of effector cells to respond to the cytokines (IL-2, IFNy, and IL-3).

The Human Immunodeficiency Virus (HIV) which causes Acquired Immunodeficiency Syndrome (AIDS) has caused a global scare with mainly poor African countries suffering the greatest burden. Treatment of HIV is more of palliation rather than cure such that there is no room for treatment interruption if treatment goals are to be met. Antiretroviral treatment is associated with short term and long term side effects which have the potential to negatively impact on the high levels of adherence to treatment that is required to maintain virological suppression and may eventually lead to development of drug resistance and treatment failure. This research aims to identify the extent to which these side effects, through possible poor adherence, impact on treatment successes by measuring the risk that side effects contribute towards treatment failure. Methods Secondary data analysis was conducted on a cohort of patients who initiated ART between 2004 and 2010 at a large tertiary facility in Johannesburg. Patients who were switched to second line ART due to treatment failure were identified. Assessment of side effects on adherence was done. The hazards of side effects among patients switching and not switching to second line were calculated using Cox proportional hazards regression adjusting for other socio-demographic and clinical predictors for treatment failure. Interaction between side effects, gender, age and that of side effects and adherence was investigated. Time dependent covariates were also investigated. Confounding was controlled using multivariate Cox regression analysis. Results There were 5285 patients in the baseline cohort with multiple entry points who contributed 16035 person-years of follow up. The cohort consisted of 63.2% females and 36.8% males. Of these 85.9% were initiated on stavudine (d4T)- based regimen, 7.1% on tenofovir (TDF), 6.3% on zidovudine (AZT)-based regimen and 0.7% on other regimens. The median and mean time at risk per subject was 2.2 and 2.3 years respectively. A total of 770 episodes of side effects due to first line ART were experienced with some patients recording multiple side effects at different time points. Adherence data were found to be missing and incoherent in some of the regimen dosages and could not be used to objectively compare patients. There were 430 patients who were switched to second line ART due to treatment failure. Relative to the group of no side effects, the adjusted hazard ratios for mild, moderate and severe side effects were 1.40 (95% CI=0.94-2.09) p=0.10; 1.72 (95% CI=1.35-2.20) p<0.01 and 1.24 (95% CI=0.65-2.35) p=0.52 respectively. Therefore, overally side effects did not seem to play a role in the time to switch to second line ART. Sex, baseline CD4 cell count, the period during which ART was initiated and the time between date of testing HIV positive and date of initiating were significantly associated with the time to switching to second line ART. Conclusion The study informs that side effects overally may not play a significant role in switching patients from first line to second line ART with the exception of moderate side effects. However, patients who experience side effects should be closely monitored and adequately counselled to help them cope with the side effects so that optimal adherence levels are maintained. Availability of adherence scores or additional information on pills that should have been taken on periods during which pills were reported to have been missed would have made the research more valuable by allowing objective comparison of adherence among patients.

An Acquired Brain Injury (ABI) can have lasting effects on the self-identity of the injured individual, but also on the self-identity of other family members. Using Contextual Family Stress Theory as a guiding theoretical framework, this qualitative study investigated how mothers experience changes and alterations in their self-identity and family identity, as well as the reconstruction of self-identity and family identity, after a child acquires an ABI. These experiences are important to capture so that clinicians and professionals may better understand the phenomenon of post-ABI self- and family identity and to help inform rehabilitation and professional services. Currently, research has been narrowly focused upon functional gains for individuals and families in rehabilitation while excluding changes in self-identity and family identity. Data were collected via semi-structured interviews and self-report measures of individual mothers' needs and perceptions of the injured child. A constructivist grounded theory analysis was used to analyze the data. Findings reveal the reconstruction processes of mothers' self-identity and family identity after a child receives an ABI, such as internal and external self-identity and intentionality in reconfiguring family identity. Furthermore, results suggest that positive adaptation in self-identity and family identity promote resilience to the changes from the child's ABI. Future research directions, theoretical, and clinical implications are discussed. / Doctor of Philosophy / An Acquired Brain Injury (ABI) can happen in many ways, such as a hard hit to the head or the brain not getting enough oxygen. Children and adolescents are among the age groups that have the highest rates of ABIs. The effects from an ABI are long lasting and impact the injured person in many ways, including their identity or sense of self. When a child receives an ABI, the parents' self-identity and the overall family identity is also affected. The goal of this study was to provide a better understanding of changes in self-identity and family identity for mothers who have a child or adolescent with an ABI. For this study, I recruited 14 mothers of a child with an ABI, and the mothers engaged in interviews and completed several short surveys. The mothers shared important information about changes in self-identity and family identity and made suggestions about how medical and rehabilitation services can better support families affected by ABIs. Findings revealed that families who are intentional about discussing changes to the family, such as role shifts or changes in routine, and expressing emotions adapt more effectively to the consequences from an ABI. Furthermore, the results suggest recommendations for rehabilitation professionals in supporting mothers and families. These include, educating the family about ABIs and involving mothers and families as part of the treatment process. Future directions for further research studies are identified as well as a discussion on best practices for clinicians.

Systemic acquired resistance (SAR) is a defense response induced by an initial localized infection that leads to the generation of long-distance immune signals that travel to distant leaves to provide enhanced resistance to subsequent infections. The lipid transfer protein (LTP) DEFECTIVE IN INDUCED RESISTANCE1 (DIR1) travels via the phloem from induced to distant leaves during SAR and may chaperone several long-distance signal candidates. In this thesis, the role of DIR1 during SAR is explored by examining the route of DIR1 movement, investigating the conservation of DIR1 structure and function, and by identifying DIR1-interacting proteins. I demonstrate that Arabidopsis plant lines with restricted cell-to-cell movement through plasmodesmata are negatively impacted in long-distance DIR1 movement, suggesting that cell-to-cell movement is important for DIR1 to access distant leaves. To elucidate the molecular function of DIR1, orthology analysis was performed with putative DIR1 orthologs. Structurally important amino acid residues that contribute to the hydrophobicity of the LTP cavity were identified, supporting the idea that DIR1 binds a hydrophobic ligand during SAR. RNAi-mediated knockdown of the DIR1 paralog DIR1-like did not impact the SAR response, supporting the idea that DIR1- like plays a lesser role in SAR. In addition, targeted protein-protein interaction assays determined that LTP1 and LTP2 interact with DIR1, and SAR phenotypic analysis of an ltp2-1 mutant supported a role for LTP2 in SAR. Lastly, a comparative proteomics approach identified several proteins with differential abundance in phloem exudates collected during the induction of SAR. Of these proteins, m-type thioredoxins, a major latex protein-like protein, and the UV-B photoreceptor UVR8 were essential for the manifestation of SAR. Together, these data provide insight into DIR1 function by identifying the importance of cell-to-cell movement through plasmodesmata, the DIR1 hydrophobic cavity, and DIR1-interacting proteins for DIR1-mediated SAR. In addition, this work identifies new phloem-localized proteins that contribute to the SAR response, providing fundamental knowledge on protein composition within the phloem during biotic stress. / Dissertation / Doctor of Philosophy (PhD)

No description available.

Background & Purpose: Sustaining an acquired brain injury (ABI) can often lead to admission to an inpatient rehabilitation program. The purpose of inpatient rehabilitation is to provide individualized, patient-centered therapy in order to facilitate community re-integration. Considering the patient perspective is beneficial for informing patient-centered care because clinicians and program administrators may develop greater awareness and understanding of patient needs and preferences. There is a lack of qualitative research investigating patient experiences and perspectives of ABI inpatient rehabilitation, and the majority of existing research was conducted in non-Canadian contexts. The present study was thus designed to describe and interpret patient experiences of an ABI inpatient rehabilitation program in urban Ontario. The purpose was to contribute to a patient lens that inpatient rehabilitation staff could consider in their work. Methods: An interpretive description approach was adopted for this qualitative study. Twelve participants were purposively sampled from a regional ABI rehabilitation program. They completed semi-structured interviews about their experiences. Interviews were transcribed, coded, and analyzed to identify major themes. Results: Three major themes were identified from the analysis and arranged around three time points. At the time point prior to admission to inpatient rehabilitation, the theme was “Life Rerouted,” where participants described their lives being diverted from what was “normal” after sustaining an ABI. Inpatient rehabilitation was seen as a way to return to their pre-injury life. The second theme described experiences within inpatient rehabilitation and was entitled, “Autonomy within Rehab.” Under this theme, participants emphasized the importance of personal autonomy over their choices and abilities while in rehabilitation, with three related sub-themes: interactions with clinicians, perceptions of institutional policy, and the involvement of family members. Under a minor theme, not directly related to aspects of autonomy, entitled “social comparisons,” participants also made comparisons of their recovery progress to other patients. The third and final theme reflected participants experiences just after discharge and was entitled, “Life (and Recovery) Go On.” Under this theme, participants described an ongoing recovery process leading to sentiments of both frustration and hope for the future. Discussion: An overarching key message was developed from these themes: “re-establishing personal identity is important to the recovery process.” Two theories (biographical disruption and relational autonomy) are used to interpret this message and describe the strategies and perspectives adopted by patients during inpatient rehabilitation as they attempted to cope with the psychosocial impacts of ABI on their lives. Conclusions: The findings of this study provide knowledge and a theoretical lens in which program staff can view and understand patients’ experiences, needs and preferences. These findings may enhance patient-centered care within the context of ABI inpatient rehabilitation. / Thesis / Master of Science (MSc)

Background: In the United States, it is estimated that 1 in 20 patients become infected with a healthcare acquired infection (HAI). Some of the complications of HAIs include increased morbidity and mortality, and drug-resistant infections. Clostridium difficile has replaced methicillin-resistant Staphylococcus aureus (MRSA) as the most important HAI in the United States by doubling its prevalence during the last decade. Significance of the study: This study is grounded on the subdiscipline of macroergonomics and highly detailed simulation. The Macroergonomic Analysis and Design (MEAD) model is utilized to identify and correct deficiencies in work systems. The MEAD process was applied to develop possible sociotechnical interventions that can be used against HAIs. Highly detailed simulation can evaluate infection exposure, interventions, and individual behavior change for populations in large populations. These two methods provide the healthcare system stakeholders with the ability to test interventions that would otherwise be impossible to evaluate. Objective/Purpose: The purpose of this study is to identify the factors that reduce HAI infections in healthcare facility populations, and provide evidence-based best practices for these facilities. The central research question is: What type of interventions can help reduce Clostridium difficile infections? Methods: We collected one year of patient archival information to include activities, locations and contacts through electronic patient records from two Virginia regional hospitals. Healthcare worker activities were obtained through direct observation (shadowing) at the two Virginia regional hospitals. Experiments were designed to test the different types of interventions using EpiSimdemics, a highly-resolved simulation software. A Clostridium difficile disease model was developed to evaluate interventions. Results: We observed a significant drop in infection cases at a regional Hospital. There is significant evidence to link this drop in HAI infections to a sociotechnical intervention. However, there is not enough information to pinpoint the specific action that caused the drop. We additionally conducted simulation experiments with two hospital simulations. Simulated sociotechnical interventions such as hand washing, room cleaning, and isolation caused significant reductions in the infection rates. Conclusions: The combined use of macroergonomics and simulation can be beneficial in developing and evaluating interventions against HAIs. The use of statistical control charts as an epidemiology tool can help hospitals detect outbreaks or evaluate the use of interventions. Use of systemic interventions in an in-silico environment can help determine cheaper, more flexible, and more effective actions against HAIs. / Ph. D.

<I>Orobanche</I> (spp.) are parasitic plants that attack the roots of many important crops. <I>O. aegyptiaca</I> penetrates the host root (aided by digestive enzymes) and forms connections to the host vascular tissue, from which it will withdraw all of its water and nutrient requirements. In order to control this weed, it is important to understand the relationship between the host and the parasite. To investigate how parasitism effects host defense pathways, we are studying the patterns of expression of host genes known to be involved in various aspects of plant defense responses. With respect to local defense responses, two genes of the isoprenoid pathway were studied, one of which is expressed in wounded tissue (<I>hmg1</I>), and another that is induced in response to wounding yet repressed in response to pathogen elicitors (squalene synthase). Genes analyzed that are associated with systemic defense include <I>PR-1</I>, <I>PR-2</I>, and <I>PR-5</I>, all of which are induced in response to pathogen attack as part of the systemic acquired resistance (SAR) response. Plant gene expression was studied using transgenic tomato plants containing <I>hmg1</I>-GUS fusions, and northern hybridization analysis of tobacco and Arabidopsis roots using gene-specific probes. Results indicated that expression of <I>hmg1</I> is induced, <I>PR-2</I> and squalene synthase are repressed, and <I>PR-1a</I>, <I>PR-1</I>, and <I>PR-5</I> are not affected in tissue parasitized by <I>O. aegyptiaca</I>. Together, these results indicate a complex response to the parasite. Whereas <I>hmg1</I> induction is consistent with <I>O. aegyptiaca</I> inflicting a simple wound-like injury, the repression of squalene synthase is consistent with plant recognition of a pathogen attack. In contrast, the failure of <I>Orobanche</I> to induce SAR- related <I>PR-1</I> in tobacco and <I>PR-1</I>, <I>PR-2</I>, or <I>PR-5</I> in Arabidopsis indicates an ability to avoid or perhaps inhibit some defense-related pathways. By comparing the regulation of these defense genes in response to <I>O. aegyptiaca</I> attack, we are able to gain a greater understanding of the host plant response to parasitization and explore potential gene candidates for future engineering strategies to create <I>Orobanche</I> resistant crops. / Master of Science

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Plants respond to pathogens both locally at the site of infection, as well as systemically in distant leaves. Systemic Acquired Resistance (SAR) is an immune response that involves the long-distance transport of SAR signal via the phloem from the site of infection to distant, uninfected leaves to establish long-lasting resistance. The Arabidopsis thaliana Defective in Induced Resistance 1 (DIR1) protein, which is required for SAR, accesses the phloem during SAR for long-distance travel to systemic leaves, and is thought to be part of a SAR signal complex. However, many questions remain about the long-distance movement of DIR1 during SAR – including the cellular route travelled to reach the phloem and whether other proteins are required for DIR1 movement. Fluorescent fusion lines of DIR1 and the related protein DIR1-like were previously created were investigated as potential tools to trace the movement of DIR1/DIR1-like during SAR. Immunoblot analysis of leaf extracts from these DIR1/DIR1-like fluorescent fusion lines revealed no signal, indicating that no fusion protein was present in these lines and therefore, they were likely not useful as a tool for assessing the movement of DIR1/DIR1-like during SAR. Lipid Transfer Protein 2 (LTP2) is required for SAR and interacted with DIR1 in a yeast-two-hybrid assay. To investigate if LTP2 is required for DIR1 movement into the phloem and long-distance, DIR1 signal was investigated by immunoblotting of phloem exudates from SAR induced ltp2-1 mutant plants. The presence of DIR1 signal in phloem exudates of local ltp2-1 leaves but not distant ltp2-1 leaves suggested that LTP2 may be required for the long-distance movement of DIR1 during SAR, but not for DIR1 to enter the phloem in induced leaves. Gene expression changes in the systemic, uninfected leaves are associated with the establishment of SAR, however, it remains less clear if there is a core set of genes important for SAR induction upregulated at the initial site of infection. To investigate this question, SAR was induced through differing treatments that first activated the PAMP-triggered immunity (PTI) pathway or Effector-triggered immunity (ETI) pathway. Common genes upregulated between all three SAR-inducing treatments were identified, revealing genes previously and currently under investigation by the Cameron lab, as well as genes that represent candidates for possible future studies. / Thesis / Master of Science (MSc)