Obesity develops when energy intake exceeds energy expenditure. Defect in the function of brown fat and skeletal muscle, two of the major tissues that contribute towards energy expenditure, lead to the development of obesity and metabolic syndrome. Our previous findings suggest that Tyk2 deficient mice become obese and develop the metabolic syndrome. Tyk2, which is a tyrosine kinase of the JAK-STAT signaling family, is important for optimal brown development and function. Since brown fat and skeletal muscle, both are derived from the Myf5+ lineage of mesenchymal stem cells, we also characterized the role of Tyk2 in the development and function of skeletal muscle. We found that Tyk2 deficient mice do not display a structural defect in skeletal muscle development; however, the function of skeletal muscle is severely impaired in these mice. Expression of troponins, which regulate the muscle contraction and muscle creatine kinase, which regulates the levels of phosphocreatine, a major fuel for skeletal muscle, is downregulated in Tyk2 deficient mice. Skeletal muscle mitochondria also display an abnormal morphology along with decreased respiration capacity, which is a function of decreased activity of complex IV of the electron transport chain. Interestingly, Tyk2 deficient mice also exhibit an increased proportion of fast, glycolytic, Type II fibers in the skeletal muscle. Using an in-vitro system for skeletal muscle differentiation, we found that Tyk2 levels increase during differentiation, suggesting a role for Tyk2 in proper development and function of the skeletal muscle. Our previous studies suggested that a kinase-inactive (Tyk2KD) form of Tyk2 is also efficient in restoring the function of Tyk2 deficient brown fat preadipocytes. We generated transgenic mice that expressed a wild type (Tyk2WT) and kinase inactive (Tyk2 KD) form of tyk2 in brown fat and skeletal muscle under Myf5 cre and in skeletal muscle using MCK cre mice. Expression of Tyk2 using the Myf5 cre (E8.0) reverts the obese and the metabolic phenotype observed in the Tyk2 deficient mice. Interestingly, expressing Tyk2 under MCK cre (E13.0) also reverts the obese phenotype, suggesting that the temporal and spatial expression of Tyk2 is critical in regulating energy expenditure. Our studies also highlight the role of Tyk2, not as a kinase, but as a component of the transcriptional assembly regulating the expression of genes invo

Dermal wound healing proliferative phase is a complicated physiological process in which many growth factors, cell types and matrix components participate. The process must be well coordinated to restore the structural and functional integrity of tissue injured. Many disorders interrupting healing process result in abnormal healing such as chronic wounds or excessive scarring. Mathematical modeling has been used to investigate many aspects of wound healing. Angiogenesis is pertinent for dermal wound healing since the cellular activities involved in tissue repair requires oxygen and nutrients to be delivered to the wound site. By using a hybrid agent-based model, we investigated the interactive dynamics of vasculature growth and collagen network growth. Our model further examine the effects of tissue oxygen tension (hypoxia, normoxia, hyperoxia) on healing process. Wound contraction is generally beneficial for the overall healing since it reduces the wound size thus reduces the chance to be infected. However, contraction going overboard may result in excessive scarring. Our model seeks to investigate the source of driving force during early and late stage of wound contraction. For the first time, skin is modeled as a fiber-reinforced anisotropic soft tissue. The effects of a dynamically orienting collagen matrix on the contraction process are thus shown. The simulation results of the model agree with the hypothesis that scar formation is the byproduct of collagen fiber synthesis and alignment in the presence of the tensile stress field generated by a wound contraction process. Multi-scale modeling is illuminating because it can help explain the phenomena at tissue level by the subcellular level events. We built a multi-scale model of general wound healing proliferative phase by embedding a TGFbeta pathway to each fibroblasts. The subcellular level model is an ODE system and the cellular level model is a hybrid agent-based model of fibroblast migration, proliferationg and collagen production. Our model clearly shows how varying mechanics of the subcellular level system results in varying tissue level pattern (collagen orientation and cell population distribution). The model can be further extended to incorporate subcellular events relating to angiogenesis and wound contraction.

Despite external bilateral symmetry, the internal organs of vertebrates are asymmetrically arranged. The development of Left-Right (LR) asymmetry is dependent on the activity of a ciliated organ known as the Kupffer’s vesicle (KV) or the embryonic node, in zebrafish and mouse, respectively. Cilia beating within the KV are essential to generate a counterclockwise flow of fluid, which leads to left-sided Ca2+ elevation. Ca2+ is a crucial morphogenic second messenger during vertebrate development. Ca2+ elevation activates targets, such as CaMK-II, which is also known as the multifunctional Ca2+/calmodulin-dependent protein kinase. Studies have linked CaMK-II to secretion (mediated through synapsin I) and to bipolar spindle formation in mammalian cells, among other cellular functions. In mammals, CaMK-II is encoded by four genes: α, β, δ, and γ. In zebrafish, like other teleost fish, gene duplication has yielded eight genes (α, αKAP, β1, β2, δ1, δ2, γ1, and γ2), which are transcriptionally active during the first 72 hours post fertilization (hpf). This dissertation has demonstrated that suppression of at least three of these CaMK-II genes disrupts proper LR-axis formation. In particular, knockdown of γ1 and αKAP CaMK-II dramatically affects southpaw (spaw) expression in the Lateral Plate Mesoderm (LPM). Interestingly, activated CaMK-II (P-CaMK-II) appears transiently in cells on the left side of the KV following Ca2+ elevation, and prior to spaw expression in the LPM. These findings indicate a role for CaMK-II in the processing or secretion of Spaw to the left LPM. In addition, cilia length and number are diminished in all three morphants, suggesting a role for CaMK-II in the process of ciliogenesis. CaMK-II is a binding partner of Kif2C, a Kinesin 13 member. Kinesin 13 members control flagellar length in Chlamydomonas, the blue-green algae and protists. The roles of Kif2C in zebrafish have never been explored, but could potentially explain cilia shortening seen in CaMK-II morphants. Zebrafish has served as an excellent model organism for the determination of the relative contributions of calcium signaling CaMK-II and Kif2C to the cellular and molecular mechanisms of LR-axis formation.

This thesis concerns the estimation of extreme quantiles on a dose-response curve. It focuses on the Robbins-Monro and up-and-down procedures. Simulation studies run in search of the LD15 and LD30 using a variety of methods suggest that the Robbins-Monro procedure is optimal in terms of Monte Carlo MSE and bias. The up-and-down procedure's performance differs in many cases only slightly from that of the Robbins-Monro process, therefore indicating its value as a practical alternative to the Robbins-Monro process for extreme-quantile estimation.

This study was initiated to look for characteristics of the immunodominant antigen(s) of Actinobacillus actinomycetemcomitans (Aa) that might help explain the high antibody titers reactive with this organism in periodontitis patients. Radioimmunoassays (RIA) and limiting dilution analysis on western blots were used to identify and characterize the immunodominant antigens of Aa in high responder patients (i.e. patients with high antibody titers). Additional experiments focused on specific responding subjects with a range of antibody titers to serotype b (AaY4). This group included both white and black subjects. Similar studies then examined the immunodominant antigens of Aa serotypes a and c. The Aa serotype specificity of the high responders was determined and further work was confined to individuals responding specifically to serotypes a or c. The results indicated that the immunodominant antigen of Aa Y 4 in all high responders was heat and papain stable. Limiting dilution analysis on western blots showed that a large diffuse band resembling carbohydrate was the immunodominant antigen. Partially purified AaY4 carbohydrate also contained the large diffuse band. Double immunodiffusion (Ouchterlony) tests indicated that the dominant antigen recognized in the carbohydrate extract by the patients' sera was the same antigen recognized by serotype b specific rabbit antiserum which has been previously shown to react with the serotype specific carbohydrate of AaY4. When the subjects with specific antibody responses covering a range of positive antibody titers were examined, 95% of the subjects were responding to the smeared serotype specific carbohydrate antigen on western blots. For serotype-a, no immunodominant antigen was common to the majority of high responding subjects. For serotype-c two antigens were immunodominant in the majority of the high responding patients: 92% had an antigen with a diffuse smeared appearance on western blots typical of a carbohydrate antigen and 67% had an approximately 15Kd antigen. The smeared antigen gave a reaction of identity with patient serum and serotype c specific rabbit antiserum in double immunodiffusion assays. These findings indicated that the immunodominant antigen for serotypes-b and-c in high responding subjects was the serotype specific carbohydrate. The same antigen was immunodominant for subjects with a range of antibody titers to AaY4. The dominant antigen was highly variable for serotype-a. These antigens were highly immunogenic. This immunogenicity may explain the enormous antibody titers observed for Aa in response to what appears to be a small quantity of antigen.

In recent years, much interest has been shown in "modeling," or fitting, primary care data to known statistical distributions. Specifically, much work has been done in studying the distributions of episodes of illness and consultations in family practices. This thesis will examine the utility of the negative binomial distribution's fit to family practice data.

The analysis of variance for experiments where the fixed effects or random effects model is appropriate is generally agreed upon with regard to testing procedures and covariance structure. It is only in experiments involving both random and fixed factors, i.e. mixed effects models, that controversy occurs as to the proper analysis. The mixed effect model has been considered by many statisticians, and several techniques have been developed for explaining its structure and performing its analysis for balanced data sets. The relationship of these techniques have been discussed in several papers as well. The simplest case of the difficulties presented by the mixed effects models occurs in the two-way cross classification model with interaction. The various models for the two-way mixed situation were examined and compared. It was found that Scheffe's model defined the effects in a meaninful way, is completely general, and provides exact tests. In situations where Scheffe's model cannot be applied, it was found that Kempthorne's model or Graybill's model should be used since they define effects in a meaningful way and, under certain assumptions, gives exact tests. Searle's model does not define the effects in the same manner as the former three models. Searle's effects are defined more for mathematical appeal and his model is designed for easy application to unbalanced cases. Consequently, his model was not found to be desirable in balanced two-way mixed effect designs. In higher order models, Scheffe's modeling techniques were found not to be practical since his test for fixed effect differences in models with more than two random effects cannot be computed. Kempthorne's models and Graybill's models both, under certain assumptions, provide straightforward tests for all effects. For this reason, their modeling techniques are recommended for higher order mixed models involving balanced data sets. Searle's modeling technique was again found unapplicable for balanced data sets in higher order mixed models for the same reasons as those in the two-way case. The results of the investigation recommends Scheffe's model for two-way situations, but Kempthorne's modeling technique and Graybill's modeling technique seem the most versatile. Although the task would be very cumbersome, further investigation is suggested in comparing Kempthorne's procedure and Graybill's procedure to Scheffe's procedure for testing fixed effect differences.

In studies of the effects of multiple drug or chemical combinations, one goal may be to detect and characterize the interactions between the agents. The techniques currently applied to this problem have limitations when the experiments involve more than 2 agents. Certain response-surface techniques require an unrealistic number of observations for studies involving a large number of agents. Current graphical methods are impossible to use in studies of 3 or more agents. In this research two statistical techniques are described that can be applied to studies with an unlimited number of agents. In the first approach, dose combinations are collected along rays or at fixed ratios. Using properties of this experimental design, an additive model is derived. Comparing the fitted dose-response curve along each ray to the curve predicted under additivity, synergistic and antagonistic interactions between the agents can be detected. Statistical testing procedures are given to determine if these are significant interactions, not due to random fluctuations in the data. Graphical techniques that enhance the interpretation of the results are described. The second approach developed in this research is a point-wise test which determines if the agents interact in an nonadditive manner. This test can be applied to each dose combination of interest After applying a multiple comparison adjustment to the resulting p-values, departures from additivity can then be characterized. These approaches are likely to be more economical than current techniques, implying that a larger number of agents can be studied in combination for the same experimental effort.

M.Com. ( Industrial Psychology and People Management) / Life role salience reflects the importance and value individuals ascribe to the roles central to their lives and identities. As such, life role salience has meaningful implications for a variety of individual as well as organisational outcomes. Prior to this study no life role salience measures had been developed or validated within the South African context. This is problematic because the use of valid measuring instruments is regarded as a prerequisite for reporting research findings, especially when unobservable constructs are measured through the use of subjective questionnaires. The objective of this study was to investigate the reliability and validity of a life role salience scale within the South African context. Specifically, the Life Role Salience Scale (LRSS) developed by Amatea, Cross, Clark, and Bobby in 1986 was examined to determine its validity and reliability using a South African sample. A quantitative, cross-sectional design was employed using a sample of South African working adults (n=300) from the Gauteng province. Confirmatory factor analyses (CFA) and exploratory factor analyses (EFA) were applied as statistical methods. CFA failed to confirm the original eight-factor structure of the LRSS. Subsequent exploratory factor analyses indicated superior fit of a five-factor version of the scale. Limitations and recommendations for future research are presented. The findings of this study highlight the importance of instrument validation and adaptation prior to application in different cultural contexts.

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Physiotherapy Johannesburg 2017 / BACKGROUND: Global life expectancy is on the rise and it is contributing to the growth of the population proportion of the elderly. More and more elderly are getting institutionalised. Functional status decline has been found to influence institutionalisation in the elderly while health-related quality of life seems to be better among the community dwelling elderly compared to the institutionalised elderly. As a result, there is increased interest on the functional status and health-related quality of life (QoL) of the institutionalised elderly. OBJECTIVES: The objectives of the study were:  to determine the demographic profile of the institutionalised elderly in Alexandra, Orange Grove and Yeoville areas of Johannesburg.  to determine the health-related quality of life and functional status of the institutionalised elderly in Alexandra, Orange Grove and Yeoville areas of Johannesburg.  to determine the relationship between functional status and health-related QoL of the institutionalised elderly in selected Johannesburg areas.  to determine the predictors of functional status and health-related QoL of the institutionalised elderly in selected Johannesburg areas. METHOD: The study utilised a cross-sectional, quantitative descriptive design. Functional status was assessed using the Physical Self Maintenance Scale (PSMS) and the Instrumental Activities of Daily Living (IADL) scale while health-related QoL was assessed using the EQ-5D-5L. The functional status and health-related QoL of the participants were assessed as a onetime event over 11 weeks. The calculated sample size was 137 participants but only 116 residents met the inclusion criteria. Questionnaires were administered individually on participants who met the study inclusion criteria after obtaining consent to get activities of daily living (ADL), IADL and health-related QoL scores. Stata version 13 was used for data analysis. RESULTS: There were 105 participants, 66 (62.86%) female and 39 (37.14%) male. The mean age was 75.2 (±8.56) years and age range being 61-98 years. The median ADL score was 5. The median IADL score for female participants was 2 while the mean IADL score for male participants was 1.95±1.70. The median EQ-5D-5L index value was 0.69. Activities of daily living (r=0.685, p<0.001) and IADL (r=0.434, p<0.006 (male); r=0.369, p<0.003 (female)) were positively correlated with health-related QoL. The correlation between health-related QoL and ADL and that between QoL and IADL were strong and moderate respectively. Independent predictors of health-related QoL were race and religion. Religion was the only independent predictor of functional status (basic ADL) for both male and all participants. There was no independent predictor of functional status (IADL) for female participants. CONCLUSION: The age range of participants was a span of four decades of life beginning from the sixth decade. Females outnumbered male participants in the ratio 1.69:1. The functional status of participants was poor (IADL) to moderate (ADL). The health-related quality of life of participants was moderate. Functional status and health-related quality of life were positively associated with strong strength. Religion and race independently predicted functional status and health-related QoL. Although the data gotten from participants’ responses were sufficient for analyses, the findings from this study cannot be generalised to all the institutionalised elderly in the selected areas in Johannesburg because the number of residents who met the study inclusion criteria and participated in the study fell short of the calculated sample size. In essence, there is the need for more studies on the functional status and health-related quality of life of the institutionalised elderly. / MT2018