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An investigation into the interaction partners of the scaffold protein human CNK1 in the NF-κB pathway

  • Authors: Moodley, Holisha
  • Date: 2019
  • Subjects: CNK1 , Scaffold proteins
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/96031 , vital:31228
  • Description: The protein connector enhancer of KSR1 (CNK1) plays a role in a number of signalling pathways including those involved in cell proliferation, cell growth and differentiation. De-regulation of these pathways has been linked to the promotion of oncogenic signalling. The involvement of CNK1 in all of these diverse pathways indicates a need to better understand the role of this protein within the cell and within key signalling networks. The research provides a platform to understand the intricate relationships that occur between these key signalling networks with the potential to identify new drug targets. CNK1 is multifunctional scaffolding protein that has binding domains that mediate and co-ordinate signalling within the MAPK, Hippo, PI3K/AKT, JNK and NF-κB pathways as well as downstream of the AT2 receptor. The activity of CNK1 is regulated through its interactions with a range of different binding partners within these pathways. Of particular interest to this research is the role of CNK1 in NF-κB signalling. The deregulation of the NF-κB pathway is implicated in chronic inflammation, tissue damage and induction of cervical and breast cancer. CNK1 has been reported to regulate the non-canonical branch of the NF-κB pathway, upstream of the IKK complex however new findings lead to uncertainty about these conclusions. In addition, the interacting partner of CNK1 in the NF-κB pathway has not been elucidated. In this thesis, we aim to identify the binding partners of CNK1 in the NF-κB pathway. First, we validate an epitope-tagged CNK1-expression construct to express elevated levels of CNK1 in cervical cancer cells. We report that the expression of myc-CNK1 is comparable to endogenous CNK1. Cells expressing elevated CNK1 levels were used in traditional co-immunoprecipitation reactions to identify potential CNK1-interacting proteins. We present data that indicates a potential role for NIK in the CNK1 signalling complex. We discuss the weaknesses of the traditional co-immunoprecipitation reactions and design an alternative co-immunoprecipitation technique with which to study CNK1-interacting partners. In this system, a promiscuous biotin ligase fused to the protein sequence for CNK1 (BirA-CNK1) is used to label proteins proximal to CNK1 with biotin. Using this BirA- CNK1-expressing construct in cervical cancer cells, we demonstrate that CNK1 interacts with IKKα-IKKβ in the NF-κB pathway.
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  • Date Issued: 2019

An investigation into the performance of smallholder irrigation schemes in Limpopo Province, South Africa: success factors, typologies and implications for development

  • Authors: Denison, Jonathan Anthony Noel
  • Date: 2019
  • Subjects: Irrigation projects -- South Africa -- Limpopo , Farms, Small -- South Africa -- Limpopo , Land use -- South Africa -- Limpopo , Water-supply -- South Africa -- Limpopo
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/92317 , vital:30709
  • Description: The research aimed to determine the factors that contribute to the success or failure of smallholder irrigation schemes in the Limpopo Province. It focussed on public-schemes where farmers share the water system Limpopo Province has more than half of the smallholder irrigation schemes in the country with an equipped area of approximately 28 000 ha. The main aims of the research were to identify key factors that explain performance and to develop a contemporary irrigation scheme typology. The research intended to provide a better perspective on how to focus investments across the multiple thematic areas that are associated with sustained and profitable irrigation farming activity. A survey of 102 irrigation schemes was conducted, comprising 82% of the population of schemes greater than 20 ha in Limpopo Province. The quantitative survey complemented prior in-depth qualitative research undertaken on Limpopo schemes. Data was consolidated into five performance indicators and 13 characteristic factors that impact performance. Schemes were viewed as technical and socio-biological systems where performance was determined by the dynamic interaction of multiple factors. The analysis was done in a complex systems framework using correlation, cluster and principle component analysis. It was postulated that over-arching concepts of productivity, profitability and manageability would explain why schemes succeed or fail. The schemes were found to be relatively very small in size with three quarters (74.8%) of them falling in the 50 to 250 ha size range, and only 11 schemes larger than 250 ha. Average plot sizes were 1.34 ha with a wide range between 0.18 and 16.25 ha. There were 65 operational schemes (equivalent to 63.7%), and 37 had failed (equivalent to 36.3%). Using a criterion for success of greater than 50% cropping intensity (to align with other studies and below which schemes can be considered to have failed), the success rate of the Limpopo schemes was 58%. The result was similar to the rest of South Africa and the same as the average rate for SADC identified in other studies using the same criterion. The schemes exhibited a mixed production purpose on average, with a significant market emphasis indicating these schemes have largely evolved from ‘food schemes’ to partly market-farming. Main crops grown were summer-maize and winter fresh-vegetables and cropping intensities on operational schemes ranged widely from 10% to 175%, with an average of 94%. Failure was associated with three dominant factors: energy type; infrastructure condition; and water resource constraints. The first two factors showed that manageability of technology was important. There is strong empirical evidence that pumped smallholder schemes are vulnerable in their physical form, prone to functional and financial failure, live much shorter lives, and perform no better than gravity-canal schemes. Out of the 37 schemes that failed, 34 (91.8%) were pumped. Pumped schemes tend to collapse suddenly while young and exhibit lower cut-off thresholds in productivity that, when crossed, trigger collapse. They also have much lower resilience to factors such as water stress or low farm-profitability. Pumped schemes need higher levels farm sophistication, market-oriented farming, and operational capability to keep the pumping pressure up. Water resource constraints were widespread, considerably more so on gravity schemes. Commercialising farmers were inhibited by lack of access to knowledge. Success was associated with numerous factors, but two findings stand out; the performance of gravity systems and the prevalence of land-exchange activity; the latter enabled by institutional flexibility and reflecting a process of ‘bricolage’ at play. Increased plot size was associated with increased commercialisation and, when larger than 1.8 ha, only commercialised farming was pursued. Market proximity seemed to play a role in increased longevity and to market access in commercialisation. These findings highlighted the importance of productivity and profitability in explaining success. Gravity schemes performed much more strongly in terms of longevity (nearly four times longer-lived) and similarly to pumped schemes in terms of cropping intensity. This was achieved under much greater water stress and with considerably worse infrastructure condition. Water efficiency was determined to be high on half of the schemes that were using short-furrow irrigation; equivalent, in a basin perspective, to drip irrigation. Two of the three top performing schemes (>150% intensity) were old gravity schemes. Farmers on approximately 75% of Limpopo smallholder schemes are currently engaging in land exchange transactions in a highly insecure and un-formalised institutional setup. Land exchange prevalence longer than two years was moderately associated with cropping intensity and strongly associated with commercialisation. This result has three important implications. First, it suggests that more land is utilised on the schemes when there is vibrant land-leasing activity. Secondly, schemes with a higher prevalence of long-term leasing seem to have a strong tendency to be more commercialised. Thirdly, the duration of the lease is significant, as neither single-season, nor annual leases yielded any positive associations, while those exchanges that were two years or longer, were associated with increased performance. These findings highlight the potential for longer-term land-exchange interventions to address the widespread low land utilisation on smallholder schemes, and to catalyse more commercially-oriented farming. An irrigation scheme typology was derived from the cluster analysis and was aligned to a contemporary irrigation farming typology. The key descriptors included technology type, purpose of farming and scheme management type. By matching scheme type to the farmer typology (or typologies), strategic decisions regarding technology choices for infrastructure, land, and water institutional interventions can be better informed. All schemes demand attention to the multiple factors required to achieve performance, not least water-tenure security, irrigation management organisational development, and infrastructure modernisation. Complexity was demonstrated by the finding that multiple factors contribute to success, and that there are many dimensions that change independently and have a cascading effect through the system in ways that are difficult to predict. Agricultural systems support to achieve productivity and profitability are essential for success. The research findings lead to the recommendation that, in addition, strategic planners must also consider the implications of the dominant factors of water-technology choices so that these are manageable, and the dynamics of farm-size change based on land exchange processes, in order to harness new opportunities to maximise irrigation scheme performance in future.
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  • Date Issued: 2019

An investigation of learning and emerging knowledge in the Mpophomeni Sanitation Education Project, Howick, KwaZulu-Natal

  • Authors: Boothway, Reinetta Louina
  • Date: 2019
  • Subjects: Environmental education -- South Africa , Mpophomeni Sanitation Education Project (South Africa) , Water quality management -- Study and teaching -- South Africa , Knowledge and learning
  • Language: English
  • Type: text , Thesis , Masters , MEd
  • Identifier: http://hdl.handle.net/10962/115377 , vital:34121
  • Description: This study took place within the broader context of water resources management in South Africa. With the democratisation of water stewardship through an enabling international and South African water policy landscape, an opportunity opened up for citizens to participate in the effective management of their own water resources. In this context, a community-engaged citizen science project known as the Mpophomeni Sanitation Education Project emerged to demonstrate how a diverse range of knowledge agents can work and learn together to better manage their water resources and address problems of sewage pollution threatening their provincial water source. The following study aimed to shed light on the learning and emerging knowledge in the MSEP. The study was conducted in three phases. Wenger’s Communities of Practice (CoP) theory provided a lens to look at Phase One, which aimed to answer the following sub-question: Is the MSEP a CoP? Wenger’s CoP theory also assisted with the investigation during Phase Two, which looked at the following question: What is the nature of learning in the MSEP? Social realist theories of knowledge and education, and Tàbara and Chabay with their Ideal Type (IT) worldviews, provided suitable lenses for Phase Three’s investigation of the following question: What is the nature of emerging knowledge in the MSEP? The main finding for Phase One is that the MSEP does function as a CoP. With its strong focus on relationships, it’s clearly defined joint enterprise of solving the problem of sewage pollution, individual and joint commitment to engage with the problem and the sharing of a repertoire of tools, ideas and practices it is cultivating a culture conducive to purposeful learning. Regarding the exploration of the nature of learning in Phase Two, findings confirming the engagement of identity with learning and the importance of context for meaning-making emerged. Finally, study findings about the nature of knowledge in the MSEP found that the knowledge practices in the MSEP that are both social and epistemic in nature are produced by a diverse range of knowledge agents in an open knowledge space.
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  • Date Issued: 2019

An investigation of the security of passwords derived from African languages

  • Authors: Sishi, Sibusiso Teboho
  • Date: 2019
  • Subjects: Computers -- Access control -- Passwords , Computer users -- Attitudes , Internet -- Access control , Internet -- Security measures , Internet -- Management , Data protection
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/163273 , vital:41024
  • Description: Password authentication has become ubiquitous in the cyber age. To-date, there have been several studies on country based passwords by authors who studied, amongst others, English, Finnish, Italian and Chinese based passwords. However, there has been a lack of focused study on the type of passwords that are being created in Africa and whether there are benefits in creating passwords in an African language. For this research, password databases containing LAN Manager (LM) and NT LAN Manager (NTLM) hashes extracted from South African organisations in a variety of sectors in the economy, were obtained to gain an understanding of user behaviour in creating passwords. Analysis of the passwords obtained from these hashes (using several cracking methods) showed that many organisational passwords are based on the English language. This is understandable considering that the business language in South Africa is English even though South Africa has 11 official languages. African language based passwords were derived from known English weak passwords and some of the passwords were appended with numbers and special characters. The African based passwords created using eight Southern African languages were then uploaded to the Internet to test the security around using passwords based on African languages. Since most of the passwords were able to be cracked by third party researchers, we conclude that any password that is derived from known weak English words marked no improvement in the security of a password written in an African language, especially the more widely spoken languages, namely, isiZulu, isiXhosa and Setswana.
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  • Date Issued: 2019

An investigation of the teaching of writing in Grade-9 English first-language classrooms: a case study of a selected government school in Namibia

  • Authors: Martins, Simone Alexandra Domingues
  • Date: 2019
  • Subjects: English language -- Rhetoric -- Study and teaching -- Namibia , English language -- Study and teaching (Secondary) -- Namibia , English language == Composition and exercises -- Study and teaching (Secondary) -- Namibia
  • Language: English
  • Type: text , Thesis , Masters , MEd
  • Identifier: http://hdl.handle.net/10962/92280 , vital:30699
  • Description: The pedagogical practice choices teachers make when teaching writing in Grade-9 English first- language classrooms, as well as the extent to which these pedagogical practices appear to enable or constrain learners’ acquisition of writing skills as per grade-specific curricular expectations, are the focus of the study. It draws from Bernstein’s (1971) curriculum and society theory, as well as genre theory. Located within the qualitative case study approach, it is designed to investigate the reasons for Grade-9 English first-language learners’ underperformance in Paper 2, the composition component of the Namibian external examinations. Drawing from the interpretivist paradigm, the study uses one-on-one interviews, semi-structured classroom observations, as well as documentary evidence of the Namibian English first-language syllabus and examples of learners’ written work, to generate data. The research site and study participants were purposefully selected. The study involves two Grade-9 English first-language teachers and classrooms at one Namibian High School, and took place from the second to the third terms of 2017.
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  • Date Issued: 2019

Analyzing the Anthropogenic Allee Effect in cycad (Encephalartos species) populations in South Africa: an evaluation of illegal trade and conservation policy

  • Authors: Earle, Sasha
  • Date: 2019
  • Subjects: Allee effect , Cycads -- Conservation -- South Africa , Botany, Economic -- South Africa , Rare plants -- South Africa , Endangered plants -- South Africa , Wild plant trade -- Law and legislation -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , Mcom
  • Identifier: http://hdl.handle.net/10962/95565 , vital:31171
  • Description: South Africa is a country known for rich biodiversity and ecosystems across the land and seascape. South Africa is one of the global hotspots for cycad diversity. Cycads are known to be the world’s most threatened plant species; declining in South Africa at a rapid pace, with threat of extinction in the wild. The main factor being harvesting from the wild for private collections. Rare cycad species’ are especially sought after by collectors. Economic theory assumes that the exploitation of a species is unlikely to result in extinction due to the increasing costs of finding the last few individuals of a species. However, the theory of the Anthropogenic Allee Effect (AAE) suggests that if consumers place a disproportionate value on a rare species’, a cycle may result whereby increased exploitation decreases population size, increasing the value of the species and, consequently, leading to its extinction in the wild. This hypothesis was tested for 37 Encephalartos species using data collected on wild populations, auction prices and the IUCN Red List status for the year 2010. It was hypothesised that an AAE was present within Encephalartos species, as three species have already gone extinct in the wild. The price per centimetre was positively correlated to the rarity of the species and the price per centimetre was negatively correlated to the wild population size. The results suggest a trend of an AAE for the year 2010. Adequate conservation policies are needed to reduce the effects of demand on illegal harvesting and prevent extinction in the wild. The effect of rarity needs to be taken into account to ensure successfulness of such policies. The most recent conservation policy implemented to protect cycads in South Africa is the Strategy and Action for the Management of Cycads in South Africa, which was introduced in 2016. The successfulness of this policy cannot, however, be analysed due to a lack of census data following its implementation.
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  • Date Issued: 2019

Another world is possible: the socialist mural in Luanda as Visual Anticipation of a New Socialist Society. We travel the SpaceWay-Black Imagination, Fragments and Diffractions

  • Authors: Siegert, Nadine
  • Date: 2019
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/146309 , vital:38514 , ISBN 9783960915300
  • Description: Book abstract. From the visual politics of the FRELIMO-liberation script in Mozambique via the brooms and spoons of Le Balai Citoyen in Burkina Faso, to the updating of images from past revolutions on Twitter and Facebook, often in the diaspora – images play a key role in the envisioning of futures and social utopia. And more than that: Revolutions, understood as moments of radical social and cultural change, are driven by images, as empirical investigations on- and offline show. But what actually constitutes the 'seismographic power' of images, and the sustainability of icons from past ruptures in terms of radicalism, such as the portraits of Burkina Faso's and Mozambiques first presidents' Thomas Sankara and Samora Machel?.
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  • Date Issued: 2019

Anti-HIV-1 integrase potency of methylgallate from Alchornea cordifolia using in vitro and in silico approaches:

  • Authors: Noundou, Xavier S , Musyoka, Thommas M , Moses, Vuyani , Ndinteh, Derek T , Mnkandhla, Dumisani , Hoppe, Heinrich C , Tastan Bishop, Özlem , Krause, Rui W M
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/162975 , vital:41001 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-019-41403-x
  • Description: According to the 2018 report of the United Nations Programme on HIV/AIDS (UNAIDS), acquired immune deficiency syndrome (AIDS), a disease caused by the human immunodeficiency virus (HIV), remains a significant public health problem. The non-existence of a cure or effective vaccine for the disease and the associated emergence of resistant viral strains imply an urgent need for the discovery of novel anti-HIV drug candidates. The current study aimed to identify potential anti-retroviral compounds from Alchornea cordifolia.
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  • Date Issued: 2019

Anticancer evaluation of ruthenium (III) complexes with N-donor ligands tethered to coumarin or uracil moieties:

  • Authors: Gramni, Larusha , Vukea, Nyeleti , Chakraborty, Abir , Samson, William J , Dingle, Laura M K , Xulu, Bheki , de la Mare, Jo-Anne , Edkins, Adrienne L , Booysen, Irvin N
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/163477 , vital:41041 , DOI: 10.1016/j.ica.2019.04.01
  • Description: In this study, the synthesis and characterization of new paramagnetic ruthenium(III) complexes: cis-[RuCl2(urdpa)] (1) {Hurdpa = 6-((bis(pyridin-2-ylmethyl)amino)methyl)uracil} and fac-[RuCl3(chrdpa)] (2) {chrdpa = 4-((bis(pyridin-2-ylmethyl)amino)methyl)-7-methoxycoumarin} are reported. These metal complexes have been comprehensively characterized by an array of physicochemical techniques and the X-ray solid-state structures of 1 and Hurdpa have been attained.
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  • Date Issued: 2019

Anticholinesterase and Antioxidant Activities of Spilanthes filicaulis Whole Plant Extracts for the Management of Alzheimer’s Disease

  • Authors: Elufioye, Taiwo O. , Unachukwu, Cynthia C. , Oyedeji, Adebola O.
  • Date: 2019
  • Subjects: Alzheimer’s disease , Cholinesterase inhibitors , Antioxidants , Spilanthes , Flavonoids , Phenolic
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/6534 , vital:46450 , xlink:href="https://10.2174/1573408015666190730113405"
  • Description: Background: Spilanthes filicaulis is a tropical herb implicated as a memory enhancer in ethnomedicine. Objective: The study investigated acetyl/butyryl cholinesterase inhibitory and antioxidant activities of different extracts of S. filicaulis whole plant and correlated them to its phytochemical constituents. Methods: The powdered whole plant was successively extracted with n-hexane, ethyl acetate and methanol. Acetyl cholinesterase (AChE) and Butyryl cholinesterase (BuChE) inhibitory activity were evaluated by Ellman colorimetry assay. Antioxidant activity was tested using 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing power and nitric oxide scavenging assays. Total phenolic, flavonoid and tannin were estimated using standard methods. Correlation was determined using Quest Graph™ Regression Calculator. Results: Various extracts exhibited concentration-dependent AChE and BuChE inhibitory activity with ethyl acetate extract being the highest with IC50 of 0.77 μg/mL and 0.92 μg/mL for AChE and BuChE respectively. The ethyl acetate extract also showed the highest reducing power when compared with the other extracts. The methanol extract had slightly higher phenolic and flavonoid content and showed the highest DPPH radical scavenging effect. DPPH scavenging, AChE and BuChE inhibition had high correlation with the total flavonoid content with R2 values of 1.00, 0.800 and 0.992 respectively while nitric oxide scavenging had high correlation with phenolics and tannins with R2 = 0.942 and 0.806 respectively. Conclusion: These results show that the extracts of the whole plant of S. filicaulis possess significant AChE/BuChE inhibitory and antioxidant properties, mostly due to its flavonoid content, suggesting the possible use of the plant in neurodegenerative diseases such as AD.
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  • Date Issued: 2019

Antihypertensive effects of the hydroethanol extract of Senecio serratuloides DC in rats

  • Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
  • Date: 2019
  • Subjects: South Africa Hypertension Computer File
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/5847 , vital:44656 , https://doi.org/10.1186/s12906-019-2463-2
  • Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p  less  0.001), diastolic blood pressure (p  less  0.01), low density lipoprotein cholesterol (p  less  0.01) and triglycerides (p  less  0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less  0.01), high density lipoprotein cholesterol (p  less  0.001) and serum nitric oxide concentrations (p  less  0.001). HESS also significantly (p  less  0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
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  • Date Issued: 2019

Antihypertensive effects of the hydroethanol extract of Senecio serratuloides DC in rats

  • Authors: Tata, Charlotte Mungho , Sewani-Rusike, Constance Rufaro , Oyedeji, Opeoluwa Oyehan , Gwebu, Ephraim Tobela , Mahlakata, Fikile , Nkeh-Chungag, Benedicta Ngwenchi
  • Date: 2019
  • Subjects: South Africa Hypertension Computer File
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/5842 , vital:44654 , https://doi.org/10.1186/s12906-019-2463-2
  • Description: Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. Results HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p  less  0.001), diastolic blood pressure (p  less  0.01), low density lipoprotein cholesterol (p  less  0.01) and triglycerides (p  less  0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p less  0.01), high density lipoprotein cholesterol (p  less  0.001) and serum nitric oxide concentrations (p  less  0.001). HESS also significantly (p  less  0.01) prevented collagen deposition in cardiac tissue. Conclusion The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.
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  • Date Issued: 2019

Antimicrobial resistance awareness program at Settlers Hospital

  • Authors: Manhanzva, Rufaro Immaculate
  • Date: 2019
  • Language: English
  • Type: text , Thesis , Masters , MPharm
  • Identifier: http://hdl.handle.net/10962/97712 , vital:31475
  • Description: Expected release date-April 2021
  • Full Text: false
  • Date Issued: 2019

Antiplasmodial Activity of the n-Hexane Extract from Pleurotus ostreatus (Jacq. ex. Fr) P. Kumm

  • Authors: Afieroho, Ozadheoghene E , Siwe-Noundou, Xavier , Onyia, Chiazor P , Festus, Osamuyi H , Chukwu, Elizabeth C , Adedokun, Olutayo M , Isaacs, Michelle , Hoppe, Heinrich , Krause, Rui W M , Abo, Kio A
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/194981 , vital:45516 , xlink:href="https://doi.org/10.4274/tjps.18894"
  • Description: Objectives: Several mushrooms species have been reported to be nematophagous and antiprotozoan. This study reported the antiplasmodial and cytotoxic properties of the n-hexane extract from the edible mushroom Pleurotus ostreatus and the isolation of a sterol from the extract. Materials and Methods: Antiplasmodial and cytotoxicity assays were done in vitro using the plasmodium lactate dehydrogenase assay and human HeLa cervical cell lines, respectively. The structure of the isolated compound from the n-hexane extract was elucidated using spectroscopic techniques. Results: The n-hexane extract (yield: 0.93% w/w) showed dose dependent antiplasmodial activity with the trend in parasite inhibition of: chloroquine (IC50=0.016 μg/mL) > n-hexane extract (IC50=25.18 μg/mL). It also showed mild cytotoxicity (IC50>100 μg/mL; selectivity index >4) compared to the reference drug emetine (IC50=0.013 μg/mL). The known sterol, ergostan-5,7,22-trien-3-ol, was isolated and characterized from the extract. Conclusion: This study reporting for the first time the antiplasmodial activity of P. ostreatus revealed its nutraceutical potential in the management of malaria.
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  • Date Issued: 2019

Application of computational methods in elucidating the isomerization step in the biosynthesis of coumarins

  • Authors: Tshiwawa, Tendamudzimu
  • Date: 2019
  • Subjects: Coumarins , Isomerization , Biosynthesis , Organic compounds -- Synthesis , Cinnamic acid
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/67646 , vital:29124
  • Description: The identity of the enzyme(s) responsible for the biosynthetic transformation of cinnamic acid derivatives to important, naturally occurring coumarins has yet to be established. This study constitutes a high-level theoretical analysis of the possibility that a recently reported molecular mechanism of the synthesis of coumarins from Baylis-Hillman adducts, may provide a viable model for three critical phases in the biosynthetic pathway Particular attention has been given to the first of these phases: i) E→Z isomerisation of the cinnamic acid precursor; ii) Cyclisation (lactonisation) to the hemi-acetal intermediate; and ii) Dehydration to afford the coumarin derivative. In order to accomplish this analysis, an enzyme capable, theoretically, of effecting this E→Z isomerisation required identification, and its potential involvement in the transformation mechanism explored. Combined Molecular Mechanics and high-level Quantum Mechanical/DFT calculations were used to access complementary models of appropriate complexes and relevant processes within the enzyme active sites of a range of eleven Chalcone Isomerase (CHI) enzyme candidates, the structures of which were downloaded from the Protein Data Bank. Detailed B3LYP/6-31+G(d,p) calculations have provided pictures of the relative populations of conformations within the ensemble of conformations available at normal temperatures. Conformations of several protonation states of cinnamic acid derivatives have been studied in this way, and the results obtained showed that coupled protonation and deprotonation of (E)-o-coumaric acid provides a viable approach to achieve the E→Z isomerization. In silico docking of the B3LYP/6-31+G(d,p) optimized (E)-o-coumaric acid derivatives in the active sites of each of the candidate CHI enzymes (CHI) revealed that (E)-o-coumaric acid fits well within the active sites of Medicago Sativa CHI crystallographic structures with 1FM8 showing best potential for not only accommodating (E)-o-coumaric acid , but also providing appropriate protein active site residues to effect the simultaneous protonation and deprotonation of the substrate , two residues being optimally placed to facilitate these critical processes. Further exploration of the chemical properties and qualities of selected CHI enzymes, undertaken using High Throughput Virtual Screening (HTVS), confirmed 1FM8 as a viable choice for further studies of the enzyme-catalysed E→Z isomerization of (E)-o-coumaric acid. A molecular dynamics study, performed to further evaluate the evolution of (E)-o-coumaric acid in the CHI active site over time, showed that the ligand in the 1FM8 active site is not only stable, but also that the desired protein-ligand interactions persist throughout the simulation period to facilitate the E→Z isomerization. An integrated molecular orbital and molecular mechanics (ONIOM) study of the 1FM8-(E)-o-coumaric acid complex, involving the direct protonation and deprotonation of the ligand by protein residues; has provided a plausible mechanism for the E → Z isomerization of (E)-o-coumaric acid within the 1FM8 active site; a transition state complex (with an activation energy of ca. 50 kCal.mol-1) has been located and its connection with both the (E)- and (Z)-o-coumaric acid isomer has been confirmed by Intrinsic Reaction Coordinate (IRC) calculations. More realistic models of the 1FM8-(E)-o-coumaric acid complex, with the inclusion of water solvent molecules, have been obtained at both the QM/MM and adaptive QM/MM levels which simulate the dynamic active site at the QM level. The results indicate that the simultaneous protonation and deprotonation of (E)-o-coumaric acid within the CHI enzyme is a water-mediated process – a conclusion consistent with similar reported processes. Visual inspection of the 1FM8-(Z)-o-coumaric acid complex reveals both the necessary orientation of the phenolic and carboxylic acid moieties of the (Z)-o-coumaric acid and the presence of appropriate, proximal active site residues with the potential to permit catalysis of the subsequent lactonisation and dehydration steps required to generate coumarin.
  • Full Text:
  • Date Issued: 2019

Applying distributed ledger technology to digital evidence integrity

  • Authors: Weilbach, William T , Motara, Yusuf, M
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/428960 , vital:72549 , https://ieeexplore.ieee.org/abstract/document/8732798
  • Description: This paper examines the way in which blockchain technology can be used to improve the verification of integrity of evidence in digital forensics. Some background into digital forensic practices and blockchain technology are discussed to provide necessary context. A particular scalable method of verifying point-in-time existence of a piece of digital evidence, using the OpenTimestamps (OTS) service, is described, and tests are carried out to independently validate the claims made by the service. The results demonstrate that the OTS service is highly reliable with a zero false positive and false negative error rate for timestamp attestations, but that it is not suitable for timesensitive timestamping due to the variance of the accuracy of timestamps induced by block confirmation times in the Bitcoin blockchain.
  • Full Text:
  • Date Issued: 2019

Arbuscular mycorrhizal fungi as a bio-indicator of soil health under agricultural management practices in South Africa

  • Authors: Sekgota, Wendy Maphefo
  • Date: 2019
  • Subjects: Soils -- Quality -- South Africa , Soil fertility -- South Africa , Fungi in agriculture -- South Africa , Mycorrhizal fungi , Vesicular-arbuscular mycorrhizas , Fungi -- Spores , Soils -- Agricultural chemical content
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/72161 , vital:30011
  • Description: This study investigated the activity of arbuscular mycorrhizal (AM) fungi as a potential biological indicator of soil health under conventional and conservation agricultural management in South Africa. An experimental trial consisting of three replicates plots under conventional and reduced tillage subdivided into twelve treatments of six crops and two fertilizer inputs was assessed over four growing seasons for various AM fungal parameters such as spore density, most probable number (MPN) of propagules percentage root colonisation and easily extractable glomalin (EEG). Cropping combinations were maize monoculture; maize soybean rotation; maize cowpea rotation; maize cowpea intercropping; maize oats intercropping and maize vetch intercropping. Resident AM fungal spore numbers and EEG protein levels were very low and no root colonization was recorded in the first two growing seasons. These findings prompted the need for the inoculation of the study site in the third growing season with a commercial AM fungal product (MycorootTM). Spore numbers, EEG concentrations and percentage root colonisation increased 8 weeks after inoculation but were significantly reduced in the fourth growing season that was not inoculated. MPN infectivity increased with inoculation particularly under conventional tillage and maize monoculture. Resident spore taxa were morphologically identified into three genera Gigaspora, Scutellospora, and Glomus. For the first two growing seasons, the maize roots were heavily colonized by a pathogenic fungus after mycorrhizal inoculation no evidence of pathogenic fungi was observed. In the fourth growing season which did not receive inoculation, root colonization started to decline. Reduced tillage, high fertilizer input combined with maize cowpea rotation (MC) and maize hairy vetch intercropping (Mv) had a significant effect (P = 0.01) on AM fungal spore numbers. Cropping systems and high fertilizer input had a significant effect on EEG concentrations in the second growing season. Overall, fertilizer application and crop type had implications for mycorrhizal activity. The soil health status in this study site was deemed low as measured by the impaired mycorrhizal activity due to agricultural management practices. Field inoculation combined with classical and molecular tools could provide a more realistic assessment of the effect of agricultural management practices on AM fungi as potential bioindicators of soil health. Therefore, AM fungi could be used as bioindicators of soil health under agricultural management practices in South African soil conditions.
  • Full Text:
  • Date Issued: 2019

Assessing household food insecurity experience in the context of deforestation in Cameroon

Assessing the abundance of non-timber forest products in relation to forest succession on the Wild Coast, South Africa

  • Authors: Njwaxu, Afika
  • Date: 2019
  • Subjects: Non-timber forest products -- South Africa -- Eastern Cape , Forest ecology -- South Africa -- Eastern Cape , Rural development -- South Africa -- Eastern Cape , Non-timber forest products -- South Africa -- Willowvale , Forest ecology -- South Africa -- Willowvale , Rural development -- South Africa -- Willowvale , Forest plants -- South Africa -- Eastern Cape
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/94090 , vital:30999
  • Description: The number of people in the Eastern Cape, South Africa, that are engaging in arable cropping has declined markedly over the last few decades. This is due to a number of factors such as a decrease in human capital because of migration of able-bodied people to urban areas, disinclination to participate in farming, raiding of crops by livestock and lack of equipment. This has resulted in abandoned croplands being invaded by trees and shrubs as the start of forest succession leading to a change in species composition and the ecosystem benefits reaped from these sites. Key amongst these benefits is a variety of non-timber forests products (NTFPs) which are an integral part of livelihoods in the area. The study was conducted in Willowvale, on the Wild Coast, South Africa. Aerial photographs were used to determine when cessation of cropping occurred in local fields and when revegetation began in order to determine the age of old fields. Botanical inventory and Braun-Blanquet scale were used to assess species richness, composition and abundance of vegetation in fields abandoned at different times. Focus groups were used to identify NTFPs found in these old fields, their uses as well as rank their importance to the local people. Results showed an increase in woody cover with time since field abandonment. Species richness also increased with age of the old field with approximately three species gained per decade. When species richness was disaggregated by growth forms, herbaceous plants were abundant in the early stages of succession, shrubs in the mature stages and trees increased steadily with time. A total of 177 species were recorded from 50 plots that were sampled during the ecological data collection. Of these, 70 species (39.6%) were identified by the focus group participants as NTFPs. The participants grouped the NTFPs into six categories namely: food, building, medicinal, craft, cultural and energy. There was an increase of richness of NTFPs with forest succession; however the proportion of NTFPs decreased with age suggesting an increase in non-useful species. This suggests that harvesting from plots of different ages would be the optimal way for local people to get access to a large variety of NTFPs.
  • Full Text:
  • Date Issued: 2019

Assessing the performance of the ‘Aquaculture Operation Phakisa Strategy’ implementation from a stakeholder perspective

  • Authors: Halley, Keagan Desmond
  • Date: 2019
  • Subjects: Marine resources -- Government policy -- South Africa , Fishery management -- South Africa , Aquaculture -- South Africa , Aquaculture industry -- South Africa , Operation Phakisa (South Africa)
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/93867 , vital:30964
  • Description: The global demand in aquatic products has seen a number of fisheries depleted worldwide through increase fishing pressure and over exploitation. South Africa in itself has 52 fisheries that are being exploited, of which 48% of these fisheries are of concern, either depleted or heavily depleted. Countries around world have now taken on the responsibility to reduce the reliance on capture fisheries and move towards a more sustainable form of ensuring fish supply. A stabilisation of fisheries stock worldwide has seen the rise of aquaculture as alternative activity that would contribute to reducing pressure on the global fisheries stocks while feeding the demand for fish protein. Aquaculture has since almost equaled the capture based fish supply, contributing to 44.1% of the world’s total fisheries products in 2014 (FAO, 2016). Over the last few years the South African government has focused on developing the aquaculture sector through the development of strategies and policies. The most recent strategy launched in 2014 was Operation Phakisa: Unlocking the Economic Potential of South Africa’s Oceans. The approach of Operation Phakisa looked at accelerating the delivery of government development priorities pertaining to the oceans economy, through development of plans and collaboration of delivery through all stakeholders (public and private stakeholders). Operation Phakisa methodology included bringing key stakeholders within academia, private and public sector, as well as civil society organisations to work together and develop strategies with clear targets that would drive the growth of their specific sectors. The year 2017 marked the midway point of the five year strategy implementation time frame, and an opportunity to assess the performance of the strategy implementation. In order to assess performance of the strategy implementation, the strategy implementation framework developed by Okumus (2003) was identified. Okumus (2003) identifies 11 implementation factors and categorizes these into four categories in the strategy implementation process, based on their role and characteristics, namely: Strategic Content (development of strategy), Strategic Context (internal and external context), Operational Process (operational planning, resource allocation, people, communication, and control) and Outcome (results of implementations process) (Okumus, 2003). The research involved the reviewing of documentation based on the strategy implementation as well as facilitated semi-structure interviews with two stakeholder groups. This was to gain an understanding from the stakeholders’ perspective, on whether the Aquaculture Operation Phakisa Strategy (AOPS) is implemented according to Okumus (2003) Strategy Implementation Framework. Two stakeholder groups were interviewed, namely the officials implementing the strategy, and the aquaculture farmers being affected by the strategy implementation. The research found that eight of out of 11 factors from Okumus (2003) Strategy Implementation Framework were identified as being gaps within the implementation of the AOPS. These gaps were identified across all four main categories for strategy implementation (Strategic content, strategic context, operational process and outcomes). They included; strategy development, organisation structure, organisational culture, leadership, resource allocation, people, communication and outcomes. Furthermore, the researcher found that the perception from the officials differed to that of the aquaculture farmers, with the officials observing a more negative perception towards factors pertaining to organisational structure, organisational culture, leadership, resources allocated, people, communication and outcomes. This negative perception was experience towards the DAFF, Branch Fisheries Management as a whole, rather than within the officials own Chief Directorate (CD:AED), responsible for implementing the strategy. The research assisted with understanding the challenges affecting the implementation of the AOPS as well as unpacked strategy implementation in literature. This aided with developing recommendation to assist with enhancing strategy implementation performance of the AOPS. The following recommendation were provided: Change management within DAFF, Branch Fisheries Management; Identify responsible structures and personnel in DAFF, Branch Fisheries Management; Developing communication platforms within DAFF, Branch Fisheries Management; Review of outcomes of AOPS; and Ensure commitment from all at DAFF, Branch Fisheries Management (leadership). The research paper presents a simple method of assessing the strategy implementation process through the use of a strategy implementation framework.
  • Full Text:
  • Date Issued: 2019
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