The methyltransferase and helicase enzymes as therapeutic targets of Zika virus : a bio- computational analysis of interactions with potential inhibitors.

Doctoral of Philosophy in Pharmaceutical Sciences. University of KwaZulu-Natal, Westville, 2019.The rampant Zika virus has received worldwide attention after becoming a global crisis following the Brazilian epidemic in 2015. From an obscure and neglected pathogen, Zika virus is now a notorious virus associated with neurological disorders in infants and adults. Since 2016, the rapid research response from the global scientific community have led to the discovery of numerous potential small molecule inhibitors and vaccines against the Zika virus. Although, in spite of this massive research initiative, there is still no effective antiviral nor vaccine that has made it out of clinical trials. The design and development of new chemical entities demands excessive cost, time and resources. Therefore, this study applies computer-aided drug design techniques, which accelerates the rational drug design process. Computational approaches including molecular docking, virtual screening, molecular modeling and molecular dynamics facilitate the filtration of large databases of compounds to sift out potential lead compounds. Furthermore, research has dedicated several resources toward FDA-approved drug repurposing. Generally, drugs have similar effects on viruses of the same family; hence drugs that have previously been effective in treating other flaviviruses, such as Dengue virus and West Nile virus, are being tested for its potential inhibition of Zika virus. However, the ability of these drugs to pass the bloodbrain barrier to treat infected neurons poses a challenge to anti-Zika virus drug discovery. This study proposes innovative strategies to design drugs that are capable of passing the blood-brain barrier, and to be able to use drugs that are impermeable via drug delivery mechanisms. This study also assesses the bioavailability and blood-brain barrier permeability of screened drugs to scrutinize the list of potential Zika virus inhibitors. Apart from identifying potential inhibitors, understanding the structural dynamics of viral targets and molecular mechanisms underlying potential inhibition of the virus is imperative. This study explores the structural and molecular dynamics of key targets of the Zika virus, the NS3 helicase and the NS5 methyltransferase enzymes, using computational approaches mentioned above and several others elaborated in this thesis. These computational methods also allowed the identification of precise interactions, amino acid residues, inhibitory mechanisms and pharmacophoric features involved in binding of lead compounds to these enzymes. IX Chapter 4 represents the first study of this thesis, which presents a concise literature background of Zika virus and identifies blood-brain barrier permeability as a core challenge in anti-Zika virus drug development. This study also provides approaches that may enable researchers to create effective anti-Zika virus drugs. Chapter 5 is the subsequent study of this thesis, which applies molecular dynamics to comparatively investigate the mechanism of inhibition and binding mode of two potential inhibitors, sinefungin and compound 5, to the NS5 methyltransferase. The specific pharmacophoric moieties of the most stable inhibitor are also identified in this study. Chapter 6 is the final study of this thesis, which examines the structural dynamics of the Zika virus NS3 helicase enzyme upon binding of ATPase inhibitor and flavivirus lead compound, resveratrol, and reports the key interactions and amino acid residues of the NS3 helicase that contribute highly to binding of resveratrol. This thesis presents an all-inclusive in silico assessment to advance research in drug design and development of Zika virus inhibitors, thus providing a greater understanding of the structural dynamics that occur in unbound and inhibitor-bound Zika virus target enzymes. Therefore, the constituents of this thesis are considered an essential platform in the progression of research toward anti-ZIKV drug design, discovery and delivery against Zika virus

Provincial variation in the effects of minimum wage laws in South Africa, 2000-2007.

Master of Commerce in Economics. University of KwaZulu-Natal, Westville 2015.Minimum wage laws are one of the most common forms of labour market legislation used internationally. Such laws were first implemented in South Africa in 2001, with the mandated wage differing across sectors. However, existing research on this topic tends to analyse the law’s effects at a national level, which does not allow for geographical variation in effectiveness. The overall objective of this research is to estimate and compare the effect of minimum wages on employment and wages in three provinces in South Africa, following the Bhorat, Kanbur and Mayet (2013) methodology. This study also considers the extent of compliance with the law. The provinces considered for analysis are KwaZulu-Natal, Gauteng and the Western Cape, which contain the largest urban centres and the bulk of economic activity in South Africa. The sectors which are included are domestic workers, retail and private security, all of which are predominately located in urban areas. The research shows that non-compliance within the security sector, across all three provinces are high, whereas, the non-compliance to the law for the retail and domestic sector, reduced substantially between the years of analysis. The results from the employment probability models showed that there was an overall decreased likelihood of employment in the domestic and security sectors, for all three provinces. KwaZulu-Natal and Gauteng saw significant increases in real wages between periods, for the domestic sector. Western Cape retail workers felt an increase in real wages but a negative effect in KwaZulu-Natal. The security sector in KwaZulu-Natal faced higher real wages, whereas a lower wage effect was found in Gauteng. It is apparent from the estimated results that the law has different effects in different provinces, which therefore provides support for the analysis of minimum wage effects at the provincial level

The establishment of in vitro screening methods for evaluating the susceptibility of sugarcane (Saccharum spp. hybrids) to the fungal disease, smut (causal agent : Ustilago scitaminea H. and P. Sydow) and the stalk borer, Eldana saccharina Walker (Lepidoptera : Pyralidae).

Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.The fungal disease smut (causal agent: Ustilago scitaminea H. & P. Sydow) and stalk borer Eldana saccharina Walker place major constraints on sugarcane agriculture in South Africa. The best approach for management is the introduction of resistant cultivars; however, conventional field-based screening for pest and disease resistance is a lengthy process. This study evaluated in vitro techniques combined with artificial inoculation of 12 week old in vitro plantlets and 8-10 week old embryogenic calli as rapid screening methods. Preliminary investigations were conducted on cultivars with known field ratings to smut and E. saccharina: NCo376, N26 and N39; and 5 „test‟ cultivars, whose identities were undisclosed until completion of experiments, were used to assess the accuracy of protocols. Infective U. scitaminea sporidia generated from teliospores, were used as inocula. Development of a callus protocol was unsuccessful due to sporidial and mycelial overgrowth, despite addition of a contact fungicide, Dithane M-45® (0.025 g/l) and a biocide/fungicide, PPMTM (5 ml/l), to media. Plantlet inoculation by injection, 1 cm above the apical meristem, resulted in 12% and 20% of smut susceptible NCo376 plantlets producing smut whips after 5 weeks when inoculated with 1 x 106 and 1 x 109 sporidia/ml, respectively. Smut whip production in 5 of the 8 (63%) cultivars inoculated with the lower sporidial concentration correlated with their field resistance ratings. In addition, whips harvested from in vitro plantlets were a valuable source of aseptic teliospores for future research. Ongoing work involves inoculation of NCo376 calli with such teliospores and maintenance on medium with PPMTM - emergence of whips from plantlets remains to be assessed. The E. saccharina screening protocol involved surface decontamination of eggs with 1% sodium hypochlorite (NaOCl) for 15 min. Feeding bioassays were conducted by placement of first instar larvae on in vitro plantlets and calli for 3 and 2 weeks, respectively. Larval mass, length and percentage infestation were recorded. Although greater larval size was expected in susceptible compared with resistant cultivars, the results did not support this. Significant differences in plantlet infestation were observed between susceptible (94-98%) and resistant (72-86%) lines. No significant differences were found in the callus feeding bioassay. However, a 24 h callus choice bioassay which investigated larval preference between callus genotypes compared with NCo376, showed significant differences and correctly discerned cultivar susceptibility according to field ratings

Fusaric acid induces oxidative stress and apoptosis in human oesophageal cancer cells.

Master of Science in Medical Biochemistry. University of KwaZulu-Natal, Durban 2016.Abstract available in PDF file

Production of activated carbon from South African sugar-cane bagasse.

Thesis (M.Sc.)-University of Natal, Durban, 2003.The South African sugar industry generates excessive amounts of sugar cane bagasse (~ 25 wt% of feed) as a byproduct during the extraction of sugar juice from cane. Although bagasse is extensively consumed in various processes, a substantial amount remains unexploited. The industry's core business is the production of refined sugar which involves among others, a step of decolourising raw sugar liquor. Activated carbons are well known adsorbents and their excellent decolourisation capabilities have been established since 1800 in the sugar industry. The possibility of making suitable in-house activated carbons from sugar cane bagasse to aid the decolourisation process of raw sugar liquor is of interest to the growing South African sugar industry. The purposes of this research study were to develop an understanding on the manufacture of activated carbons from sugar cane bagasse, produce suitable activated carbons on a laboratory scale, characterize them and subsequently determine their sugar decolourisation capabilities under simulated conditions. The application of the two-step physical method of processing was found to be the most effective and feasible route to produce activated carbons from sugar cane bagasse for the purposes of decolorizing unrefined sugar. A semi-batch process was developed whereby compressed sugar cane bagasse was pyrolysed under a nitrogen atmosphere at a heating rate of 10 °C/min to the final pyrolysis temperature for a desired hold time resulting in bagasse chars with a rudimentary pore structure. These bagasse chars were subsequently subjected to partial and controlled gasification with a steam/nitrogen mixture at higher temperatures to produce the final activated carbon product. Both pyrolysis and activation were carried out in a pyrolysis furnace that was modified to represent a fixed bed reactor system. The process was designed such that it included a steam supply and a gas cleaning system. Feasible processing conditions were established by varymg the temperature, hold time and partial pressure of steam in the pyrolysis furnace. The bagasse chars and final activated carbons were characterized with respect to surface area, pore volume, pore size distribution, methylene blue number, iodine number and molasses number. The optimum pyrolysis conditions were found to be at heating rate of 10°C/min to the final pyrolysis temperature of 680 °C for a hold time of 1 hour, which gave rise to microporous carbons. Increasing the steam partial pressure and activation temperature during activation of bagasse chars resulted in the gasification reaction proceeding at a much faster rate leading to well developed mesoporous activated carbons having high adsorption capacity for large colour bodies present in molasses and sugar liquor. This was achieved by activating bagasse chars at a temperature of 900°C for 2 hours with a steam / nitrogen mixture of 1:0.6 which resulted in 50% bum-off being reached. Excellent powder and granular activated carbons were produced from sugar cane bagasse fibres by the established process with the latter being mixed with refined sugar prior to pyrolysis and activating for half an hour extra. A typical final activated carbon produced in this research possessed a BET surface area of 995 m2/g, pore volume of 0.82 crrr'zg, iodine number of 994 mg/g, molasses number of 700 and methylene blue number of 256 mg/g. High ash content in the bagasse raw material tends to decrease the surface area and pore volume for adsorption of the final activated carbon. Both granular and low ash bagasse activated carbons possess high adsorption capacity to remove large colour bodies from molasses and brown liquor solutions and compare well with commercial Norit N2 carbon . Approximately 80% colour removal was achieved using 0.5 g carboni 100g brown liquor. The bagasse activated carbons were stable in acidic and basic brown liquor solution and maintained their high decolourisation potential. The ability of bagasse activated to replace commercial activated carbons has been proven in this study. The option of producing both granular and powder activated carbons provide flexibility of the sugar industry to choose between batch and continuous adsorption systems during sugar decolourisation. This research has established that the fact that excellent sugar decolourising activated carbons can be produced from South African sugar cane bagasse fibres. However, more research needs to be carried out in order for the sugar industry to take this project to the commercial stage and it is suggested that a pilot study and an economic study be carried out

The contracting world of girls at puberty: Violence and gender-divergent access to the public sphere among adolescents in South Africa

This Population Council working paper describes a participatory mapping project undertaken with single-sex groups of grade 5 and grade 8–9 children in urban and rural KwaZulu-Natal, South Africa. At grade 5, female self-defined community areas were equal to or larger in size than those of males in both sites. However, wide gender divergence in access to the public sphere was found among grade 8–9 children. Although curtailed spatial access, especially in urban areas, is intended to protect post-pubescent girls, grade 8–9 girls reported most spaces in their small navigable areas unsafe. Reducing girls’ access to the public sphere does not increase their perceived safety, but may instead limit their access to opportunities for human development

Physiological responses of selected African sorghum landraces to progressive water stress and re-watering

Sorghumis particularly drought tolerant compared with other cereal crops and is favoured for subsistence farming in water scarce regions of the world. This study was conducted to identify South African sorghum landraces with superior drought tolerance compared with a drought-tolerant breeding line (P898012). Seedlings of 14 South African sorghumlandrace accessions were initially screened for drought tolerance by assessing percentage leaf water content (LWC) during progressive water deficit. Four landraces (designated LR5, LR6, LR35, and LR36) recorded higher LWC than P898012. These were subsequently evaluated with P898012 during the reproductive growth stage, for their physiological responses to mild (4 days) and severe (6 days)water stress treatments and a moderate re-watered treatment on day 7. Plant height, soil moisture, and LWC were measured during harvests. Chlorophyll, carotenoid, and proline contents were quantified. All five genotypes maintained LWC above 80% during mild and severe stress treatments. For LR35 and LR36, LWC were recorded within 8% less in comparison to their well-watered controls following the moderate re-watered treatment. Significantly higher chlorophyll and carotenoid contents were recorded for both LR6 and LR35 in comparison to P898012 during severe stress. When LWC was reduced in LR36 (to 73.68%) and LR35 (to 73.51%), their proline content significantly increased by 14- and 16-fold, respectively. In this study,we have identified four previously uncharacterised sorghum genotypes exhibiting drought tolerance and described their physiological responses during water deficit and moderate re-watering. Aside from their application to breeding, these landraces are valuable resources to elucidate genetic mechanisms that enable drought tolerance in South African sorghum.Council for Scientific and Industrial Research (CSIR) - Biosciences, Pretoria and the Gauteng Department of Agriculture and Rural Development (GDARD), South Africa. Ms Natrisha Devnarain was awarded a Professional Development Programme (PDP) PhD Scholarship from DST-NRF to work on this project.http://www.elsevier.com/locate/sajb2017-03-31hb201

Enhanced photocatalytic degradation of acetaminophen from wastewater using WO3/TiO2/SiO2 composite under UV–VIS irradiation

peer-reviewedThe full text of this article will not be available in ULIR until the embargo expires on the 26/8/2019This study investigates the photocatalytic degradation of acetaminophen (Ace) from synthetic wastewater by individual TiO2, TiO2/SiO2 and/or WO3/TiO2/SiO2 composite under UV-VIS illumination. To characterize changes in their morphology and crystal structures before and after treatment, Χ-ray diffraction (ΧRD), Fourier transform infrared spectroscopy (FTIR) , DRS UV-VIS absorption spectra, Brunaer-Emmer-Teller (BET) and scanning electron microscopy (SEM) techniques were used. The effects of varying loading ratios of the WO3 on the TiO2/SiO2 composite for Ace degradation were studied. Operating parameters such as initial concentration, reaction time, dose of photocatalyst and pH were tested. Degradation by-products were also presented. It is found that the photodegradation performance of the WO3/TiO2/SiO2 composite as a photocatalyst in this study could be enhanced by optimizing the loading ratio of the WO3. About 3% (w/w) of WO3/TiO2/SiO2 was found to improve the degradation of Ace from 33% to 95% at the same initial concentration of 5 mg/L. The resulting oxidation by-products included hydroquinone and 1,4-benzoquinone. Under the same conditions, the result of photocatalytic degradation by the 3% (w/w) of WO3/TiO2/SiO2 composite was significantly higher (95%) than that by the individual TiO2/SiO2 (42%) and/or by the TiO2 alone (33%). Under optimized conditions (1.5 g/L; 3% (w/w) of WO3/TiO2/SiO2 composite; pH 9; 4 h of reaction time), 95% of Ace removal with an initial concentration of 5 mg/L could be attained. However, the treated effluents still could not meet the discharge standard of less than 0.2 mg/L set by China’s and US legislation. This indicates that further subsequent treatment like biological processes is still necessary for completing the removal of target pollutant from the wastewater samples

Service learning: Connecting higher education and civil society – Are we meeting the challenge?

The decline in civic participation, dwindling support for social services and deficits in state budgets, has created a climate in which higher education, supported by several policies, has to make a commitment to contribute to the reconstruction and development of society by linking academic programmes to community-based priorities (Campbell 2002). In South Africa, the Community Higher Education Service Partnership (CHESP)was implemented by the Joint Education Trust in response to the directive of the White Paper on Higher Education (1997) to develop and research pilot academic programmes through community, university and service sector partnerships. The purpose of these partnerships was to: contribute to the empowerment and development of local communities; make higher education policy and practice responsive to community priorities, and, enhance service delivery to participating communities (Lazarus 2001). Itwas anticipated that these partnerships would inspire a sense of citizenship; engender new forms of problem solving knowledge; capacity and practice; produce a new generation of leaders, and, contribute to national development (Nuttal, Bruzas and Mosime 2000). To test the relevance and practical application of these holistic and developmental concepts this article which is based on an intensive study undertaken atfive university sites with ten multidisciplinary modules, explores the position of service learning and its impact on partnerships. The conclusion reached was that although the ultimate aim was to connect higher education and civil society, the formalisation of existing policies and institutional arrangements are necessary to facilitate meaningfulpartnerships