Cosmic-ray fluctuations are monitored by neutron monitors using several different kinds of proportional counter tubes. An important component of these monitors is the electronic subsystem that registers and counts output pulses from these counter tubes. Part of the electronic subsystem is a specific preamplifier. The pulse-height distribution curve of the existing preamplifier used in the neutron monitor system at the Centre for Space Research at the North-West University was found to be incorrect, and therefore the pulse-height information cannot be used for further research on the counter tube characteristics. A correct pulse-height distribution implies that the envelope of the pulse, as generated by an amplifier, has a very specific shape as a result of the physics that governs the generation of pulses in the neutron counter tube. It was therefore proposed that a new charge-sensitive preamplifier be synthesized to provide an output that provides the correct pulse-height distribution graph for a neutron monitor system. The Centre for Space Research at the North-West University is in the process of designing and building a new mini neutron monitor system. The new charge-sensitive preamplifier will be implemented into this updated system. Ultimately, the electronic subsystem must be able to provide a pulse-height distribution graph at the push of a button, thus making the preamplifier a key component in the new design. In this dissertation the theory of charge-sensitive amplifiers is researched following a design science research methodology. The results showed that a charge-sensitive amplifier can be synthesized to address both the real-world requirements and the theoretical requirements of this research. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Obesity is strongly associated with hypertension and cardiovascular diseases. An activated renin-angiotensin system (RAS) has long been suggested as a critical contributor to elevated blood pressure with obesity. Angiotensin II (AngII), the main effector of an activated RAS, can be catabolized by angiotensin-converting enzyme 2 (ACE2) to form angiotensin-(1-7) (Ang-(1-7)), which, acting through the mas receptor (MasR), has been shown to oppose the effects of an activated RAS. Therefore, further understanding of the mechanisms of this counter-regulatory arm, called the ACE2/Ang-(1-7)/MasR axis, may lead to new therapies for obesity-induced hypertension. Previously, we demonstrated that differences in the regulation of ACE2 in a tissue-specific manner contribute to sexual dimorphism of diet-induced obesity-hypertension in mice. Whereas male mice fed a high fat (HF) diet developed hypertension, HF-fed female mice were protected from obesity-hypertension, and this was associated with increased activity of ACE2 in adipose tissue of females. Both upregulation of adipose ACE2 and protection against obesity-hypertension were lost when females were ovariectomized (OVX). We hypothesized that estrogen-mediated increases in adipose ACE2 reduce the AngII/Ang-(1-7) peptide balance and protect females from obesity-hypertension. To test this hypothesis, we first determined if estrogen restores protection of Ovx female mice from obesity-hypertension, and therapeutically protects male mice from obesity-hypertension. We demonstrated that estrogen administration to Ovx HF-fed females activates adipose ACE2, reduces plasma Ang II concentrations, and decreases blood pressure in wildtype, but not of ACE2-deficient obese females. In contrast, estrogen administration to HF-fed male mice had no on the development of obesity-hypertension, regardless of genotype. These results demonstrate that estrogen protects female mice from obesity-hypertension through an ACE2-dependent mechanism. Next we defined the role of MasR deficiency on the development of obesity-hypertension in male and female mice. In HF-fed MasR-deficient female mice, diastolic blood pressure (DBP) was significantly elevated compared to LF-fed controls, suggesting that protection from obesity-hypertension was abolished by MasR deficiency. In contrast, HF-fed male mice with MasR deficiency exhibited reduced blood pressure compared to wildtype controls which was associated with reduced cardiac function. Overall, these studies indicate that the ACE2/Ang-(1-7)/MasR axis plays an important role in sexual dimorphism of obesity-hypertension, and in the regulation of cardiac function. Moreover, these studies suggest that the effects of this counter-regulatory arm of the RAS may be sex-specific.

Background: Vitamin D is crucial for skeletal muscle function. 25-hidroxyvitamin D (25(OH)D) has been correlated with skeletal muscle mass and intramyocellular lipid (IMCL) content. The purpose of this study was to understand how calcitriol, the active vitamin D metabolite, directly affects myocellular size and lipid partitioning. Methods: C2C12 myotubes were treated with calcitriol (100nM) or vehicle control for 24 or 96 h. Myotube diameter and protein synthesis rate were measured to determine effects of calcitriol on myocellular size. Intramyocellular triacylglycerol (IMTG), diacylglycerol (DAG), and ceramide content were measured by LC/MS. Expression of genes involved in lipid packaging and lipolysis were measured by RT-PCR. Insulin-stimulated phosphorylated Akt (Thr 308) was determined by western blot. Results: Calcitriol did not affect myocellular size or protein synthesis rate. Calcitriol increased total DAG and ceramides in a sub-species specific manner. Calcitriol increased IMTG area, but did not affect total IMTG content. Calcitriol reduced mRNA content of diglyceride acyltransferase and increased mRNA content of lipid packaging genes. Calcitriol did not negatively affect insulin-stimulated pAkt. Conclusions: These results suggest calcitriol directly alters lipid content and packaging in skeletal muscle cells. Altering the expression of lipid packaging genes and increasing IMCL subspecies content may be mechanisms by which vitamin D improves skeletal muscle function in vivo.

Problem/Purpose: Process prioritisation is an ill-structured and complex problem that remains a mystery phase in business process management (BPM) research. More explorative approaches are called upon to tackle process management problems, to facilitate process innovation and to design new processes in dynamic environments. This dissertation aims (i) to design and evaluate a Prioritisation and Categorisation Method (PCM) for addressing process prioritisation problems; and (ii) to explore process innovation by disruptive technologies. Research methods: This research follows the design science research (DSR) paradigm. The design exploration and the engaged scholarship approaches are also adapted. The demonstration and evaluation of the Prioritisation and Categorisation Method have been conducted with case studies in large Swedish companies, i.e. Seco Tools and Ericsson. An empirical study of the impacts of disruptive technologies on process innovation was conducted at a large insurance company in Sweden. Results: This research has led to the design and evaluation of the PCM: a new context-aware, effective and holistic method for BPM. In addition, the lessons learnt from the insurance case deepened the understanding of the challenges that are faced by a company when exploring new capabilities (e.g. processes and IT) for future business. Such lessons also emphasise the necessity of configuring PCM based upon business contingencies and industry factors in process prioritisation. Contributions: This dissertation contributes a novel method to explore BPM in a holistic, yet flexible and effective way. The challenges identified in process innovations improve the configuration capabilities of the PCM through a deeper understanding of the dynamic capabilities within organisations (Capability Layer Model-CLM). This research contributes design knowledge to DSR in the forms of the PCM as an invention, and the three design principles for the PCM: design by holistics, design by commitments and design by explorations. The research is evaluated as good BPM and good design science research.

The inhibitor of DNA binding protein 4 (ID4) is a dominant negative regulator of basic helix loop helix (bHLH) family of transcription factors.1 Recently, Patel et al., demonstrated that inhibitor of differentiation 4 (ID4) acts as a tumor suppressor and its loss, frequently observed in prostate cancer, promotes castration-resistant prostate cancer (CRPC) through constitutive androgen receptor (AR) activation.2 However, the mechanism by which loss of ID4 promotes constitutively active AR signaling in the CRPC conditions is unknown. The rationale of the present study was to unravel the underlying molecular mechanisms through which loss of ID4 potentiates AR signaling in this setting. Initially, chromatin immunoprecipitation (ChIP) assay results demonstrated a significant increase in binding of AR to its respective response elements on PSA, FKBP51, TMPRSS2, and ETV1 promoters in L(-)ID4 cells, further implicating constitutive AR activity. Among the notable findings, proteomic profiling between prostate cancer cell line LNCaP (L+ns) and LNCaP lacking ID4 (L(-)ID4) revealed elevated protein levels of Heat shock protein 27 (Hsp27) and the 52-kDa FK506-binding protein (FKBP52), suggesting a role for these AR-associated co-chaperones in promoting constitutively active AR signaling in L(-)ID4 cells. Interestingly, protein interaction studies further confirmed a direct interaction between ID4 and FKBP52 in vitro but not with AR. Recent evidences suggest that FKBP52 is a positive regulator of AR signaling in cellular and whole animal models.3-6 Thus, we hypothesized that ID4 acts as a tumor suppressor by selectively regulating AR activity through interaction with FKBP52. To address the underlying mechanism, we blocked the FKBP52-AR signaling using a specific inhibitory compound known as MJC13.4, 6-7 The results demonstrated that MJC13 effectively inhibited AR-dependent expression and activity in a dose-dependent manner. In addition, xenograft studies further confirmed that inhibiting FKBP52-regulated AR activity via MJC13 significantly attenuated the growth of subcutaneous L(-)ID4 xenografts in vivo. Collectively, our results suggested that ID4 selectively regulates AR activity through direct interaction with FKBP52 in vitro, and, its loss promotes CRPC through FKBP52-mediated AR signaling. Increased AR signaling along with a subsequent decrease in ID4 expression levels in prostate cancer strongly supports this model.

Endogenous bioelectric fields guide morphogenesis during embryonic development and regeneration by directly regulating the cellular functions responsible for these phenomena. Although this role has been extensively explored in many peripheral tissues, the ability of electric fields to regulate wound repair and stimulate regeneration in the mammalian central nervous system (CNS) has not been convincingly established. This dissertation explores the role of electric fields in regulating the injury response and controlling the regenerative potential of the mammalian CNS. We place particular emphasis on their influence on astrocytes, as specific differences in their injury-induced behaviors have been associated with differences in the regenerative potential demonstrated between mammalian and non-mammalian vertebrates. For example, astrocytes in both mammalian and non- mammalian vertebrates begin migrating towards the lesion within hours and begin to proliferate after an initial delay of two days; subsequently, astrocytes in non-mammalian vertebrates support neurogenesis and assume a bipolar radial glia-like morphology that guides regenerating axons, whereas astrocytes in mammals do not demonstrate robust neurogenesis and undergo a hypertrophic response that inhibits axon sprouting. To test whether injury-induced electric fields drive the astrocytic response to injury, we exposed separate populations of purified astrocytes from the rat cortex and cerebellum to electric field intensities associated with intact and injured mammalian tissues, as well as to those electric field intensities measured in regenerating non-mammalian vertebrate tissues. Upon exposure to electric field intensities associated with uninjured tissue, astrocytes showed little change in their cellular behavior. However, cortical astrocytes responded to electric field intensities associated with injured mammalian tissues by demonstrating dramatic increases in migration and proliferation, behaviors that are associated with their formation of a glial scar in vivo; in contrast, cerebellar astrocytes, which do not organize into a demarcated glial scar, did not respond to these electric fields. At electric field intensities associated with regenerating tissues, both cerebellar and cortical astrocytes demonstrated robust and sustained responses that included morphological changes consistent with a regenerative phenotype. These results support the hypothesis that physiologic electric fields drive the astrocytic response to injury, and that elevated electric fields may induce a more regenerative response among mammalian astrocytes.

Hyperhomocysteinemia (hHcys) is a widely known pathogenic factor in the progression of end-stage renal disease (ESRD) and it is also associated with an increased risk for injurious cardiovascular pathologies during ESRD. HHcys is linked to the formation and activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, characterized as a critical early mechanism initiating the inflammatory response. NADPH oxidase (NOX)-derived reactive oxygen species (ROS) mediate the activation of the NLRP3 inflammasome in podocytes in response to elevated levels of homocysteine (Hcys) in vitro and in vivo. However, it remains unknown how NLRP3 inflammasome activation is triggered by NOX. The aim of the present study sought to determine the signaling cascade that triggers glomerular injury and sclerosis during hHcys mediated by Vav2, a guanine nucleotide exchange factor (GNEF). Using both genetic and pharmacological interventions of Vav2, we first tested whether this GNEF is involved in hHcys-induced NLRP3 inflammasome activation in podocytes by its role in activation of the Rac-1-NOX complex. Further, we explored whether pharmacological targeting of Vav2 activation may regulate NLRP3 inflammasome signaling pathway during hHcys-induced glomerular injury. We found that mice with hHcys (on the FF diet) or oncoVav2 (a constitutively active form of Vav2) transfection in the kidney exhibited increased colocalization of NLRP3 with apoptosis-associated speck-like protein (ASC) or caspase-1 and elevated IL-1β levels in glomeruli, indicating the formation and activation of the NLRP3 inflammasome. This glomerular NLRP3 inflammasome activation was accompanied by podocyte dysfunction and glomerular injury, even sclerosis. Local transfection of Vav2 shRNA plasmids significantly attenuated hHcys-induced NLRP3 inflammasome activation, podocyte injury, and glomerular sclerosis. In cultured podocytes, Hcys treatment and oncoVav2 transfection increased NLRP3 inflammasome formation and activation. This NLRP3 activation was inhibited by Vav2 shRNA, associated with reduction of Rac-1 activity and ROS production. Administration of NSC23766, a Rac-1 inhibitor substantially attenuated inflammasome formation, desmin expression and decreased podocin expression in glomeruli of hHcys mice. These results suggest that elevated Hcys levels activate Vav2 and thereby increase NOX activity, leading to ROS production. ROS trigger NLRP3 inflammasome activation, podocyte dysfunction and glomerular injury. Therefore, the present study defines a novel mechanism underlying hHcys-induced NLRP3 inflammasome activation and its progression to ESRD.

Replenishment is an important process in automotive industries. It is the process by which parts required at assembly lines are stored and organized in assembly lines supermarket. Over many years replenishment have been done with the aim of positively impacting the varying demand frequency of articles in multi flows mixed-model assembly lines (MMALs) operating in just-in-time (JIT) fashion. However, a series of successive replenishment actions have negative impacts on the number of reallocation movements of parts within volume flows of supermarkets especially within a context of multi-flows supermarkets (MFSs). The cost of movements of parts within the supermarket has not been taken into consideration in previous replenishment methods. This is a significant problem since both un-optimized reallocation movements, and articles misplacement resolutions lead to production halts which cost assembly plants valuable time and money. Therefore, this research study proposes a replenishment method that optimizes flow of material within multi-flow assembly lines supermarkets and hence reduces the cost due to reallocation movement of multi-flow assembly lines supermarkets. The proposed method has been evaluated in the context of Volvo automobile engine assembly plant in Skövde. The proposed replenishment method has been evaluated by conducting an experiment using real-world data for the assembly plant in context. Performance metrics such as accuracy, F1-score, precision, sensitivity, and specificity were used to demonstrate the utility and validity of the proposed method. The evaluation results showed that the proposed method for optimizing material flow in supermarkets performed better than the existing method. In addition to utility, the proposed method provides contribution to knowledge by providing means for the industry to adopt replenishment method that takes into consideration the cost of reallocation movements of the parts within the supermarket.

BECN1 is a haploinsufficient tumor suppressor gene that is monoallelically deleted or epigenetically silenced in many human cancers. In breast cancer, 40% of tumors exhibit monoallelic deletion of Beclin 1. Additionally, low Beclin 1 mRNA expression is observed in aggressive breast cancer subtypes and reduced expression is an independent predictor of overall patient survival. The role of Beclin 1 in cancer has almost exclusively been attributed to its function in autophagy. However, our lab demonstrated an alternative role for Beclin 1 in the regulation of growth factor receptor signaling that could contribute to cancer. The goal of my thesis project was to investigate the molecular basis by which Beclin 1 regulates breast tumor growth and progression in vivo. Using in vivo models, I discovered that Beclin 1 promotes endosomal recruitment of hepatocyte growth factor tyrosine kinase substrate (HRS), which is necessary for sorting receptors to intraluminal vesicles for signal silencing and degradation. Beclin 1-dependent recruitment of HRS results in the autophagy-independent regulation of endocytic trafficking and degradation of the epidermal growth factor (EGFR) and transferrin (TFR1) receptors. When Beclin 1 expression is low, endosomal HRS recruitment is reduced and receptor function is sustained to drive tumor proliferation. An autophagy-independent role for Beclin 1 in regulating tumor metabolism was also observed. Collectively, my results demonstrate a novel role for Beclin 1 in impeding tumor growth by coordinating the regulation of growth promoting receptors. These data provide an explanation for how low levels of Beclin 1 facilitate tumor proliferation and contribute to poor cancer outcomes, independently of autophagy.

In this study, we investigated differential activation and the role of two mTOR complexes in cell migration of prostate cancer cells. Specific knock-down of endogenous RAPTOR and RICTOR by siRNA resulted in decreased cell migration in LNCaP, DU145, and PC3 cells indicating that both mTORC1 and mTORC2 are required for cell migration. EGF treatment induced the activation of both mTORC1 and mTORC2 as determined by complex-specific phosphorylation of mTOR protein. Specific knock-down or inhibition of Rac1 activity in PC3 cells blocked EGF-induced activation of mTORC2, but had no effect on mTORC1 activation. Furthermore, the over-expression of constitutively active Rac1 (Rac1Q61L) resulted in significant increase in cell migration and activation of mTORC2 in PC3 cells, but had no effect on mTORC1 activation. Constitutively active Rac1 (Rac1Q61L) in PC3 cells was localized in the plasma membrane and was found to be in a protein complex which contained mTOR and RICTOR proteins, but not RAPTOR. In conclusion, we suggested that EGF-induced activation of Rac1 causes the phosphorylation/activation of mTORC2 via RICTOR, specific regulator of mTORC2 activation in numerous cancer cells. The major role played by mTOR in a wide array of cancers has in the recent decades led to the development of numerous mTOR inhibitors. One of the drawback of these first generation mTOR inhibitors are that m TORC1 activity is inhibited but effect on mTORC2 activity require high dosages and prolonged exposure in different cancer cell types including HeLa, PC3, LNCaP, and A549. High dosage of rapamycin and its associated rapalogs required for mTORC2 inhibition is clinically unsuitable. Studies have shown that the dual mTORC1/C2 inhibitors trigger feedback loops causing metastasis and affect the cell viability of normal tissues in vitro and in vivo. There is a need for specific mTORC1 and mTORC2 inhibitor, which overcome the disadvantages of the previously developed mTOR inhibitors. The Rac1-RICTOR axis suggested in this study could be used as a potential target for the development of mTORC2 inhibitor and lead to a potential therapeutic treatment for aggressive prostate cancer.