Analysing an audit cycle: a critical realist account
- Boughey, Chrissie, McKenna, Sioux
- Authors: Boughey, Chrissie , McKenna, Sioux
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66741 , vital:28988 , ISSN 1470-3300 , https://doi.org/10.1080/03075079.2015.1072148
- Description: Pre-print , This paper reports on the use of a framework developed from Bhaskar's critical realism and Archer's social realism to analyse teaching- and learning-related data produced as a result of the first cycle of institutional audits in the South African higher education system. The use of the framework allows us to see what this cycle of audits did achieve, namely some change in structural systems related to teaching and learning alongside the appointment of key agents. It also allows us to see how the stagnation of sets of ideas about teaching and learning in the domain of culture may mean that an assurance of the quality of learning experiences for all students remained elusive.
- Full Text:
- Date Issued: 2017
- Authors: Boughey, Chrissie , McKenna, Sioux
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66741 , vital:28988 , ISSN 1470-3300 , https://doi.org/10.1080/03075079.2015.1072148
- Description: Pre-print , This paper reports on the use of a framework developed from Bhaskar's critical realism and Archer's social realism to analyse teaching- and learning-related data produced as a result of the first cycle of institutional audits in the South African higher education system. The use of the framework allows us to see what this cycle of audits did achieve, namely some change in structural systems related to teaching and learning alongside the appointment of key agents. It also allows us to see how the stagnation of sets of ideas about teaching and learning in the domain of culture may mean that an assurance of the quality of learning experiences for all students remained elusive.
- Full Text:
- Date Issued: 2017
Analysis of a foundational biomedical curriculum: exploring cumulative knowledge-building in the rehabilitative health professions
- Authors: De Bie, Gabrielle
- Date: 2017
- Subjects: Medical education -- Curricula , Human anatomy -- Study and teaching -- Curricula , Physiology -- Study and teaching -- Curricula , Occupational therapy -- Study and teaching -- Curricula , Physical therapy -- Study and teaching -- Curricula , Medical rehabilitation -- Study and teaching -- Curricula , Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/18617 , vital:22361
- Description: This study was motivated by the researcher's experience that students in the rehabilitative health professional programmes were finding it difficult to access fundamental knowledge upon which their professional practices and clinical contexts are based. An important focus of the research was the extent to which cumulative knowledge-building was impacted after the foundational biomedical curriculum became an interdisciplinary programme. The study explored whether the organisation of the interdisciplinary foundational curriculum served the fundamental needs of the professions, and whether, as a matter of social justice, students' access to powerful knowledge was enabled by the form that the fundamental curriculum assumed. This curriculum study at a particular Faculty of Health Sciences foregrounds the structuring, organisation and differentiation of disciplinary knowledge, and reflects a twenty year period that included not only transitions in professional education but also extensive transformation in, and a different approach to, health delivery. At the institution, physiology and anatomy, the biomedical sciences basic to the health professions, underwent disciplinary merging and subsequent altered positioning in curricula. Medicine opted for a problem-based learning approach whereas the rehabilitation health sciences did not. Legitimation Code Theory (LCT) provided the means for analysis of the extent to which interdisciplinary organisation in the foundational curriculum for Physiotherapy and Occupational Therapy enabled integrative, cumulative building of knowledge for professional and clinical contexts. Specialisation and Semantics dimensions of Legitimation Code Theory were used to reveal the principles underpinning practices, contexts and dispositions of Anatomy and Physiology at the Faculty of Health Sciences over a twenty year period post democratisation in South Africa (1994 - 2013). Disciplinary positioning in curriculum prior- and post-merger, were compared and contrasted. LCT were used to characterise the distinctiveness of Physiotherapy and Occupational Therapy at the university including the kind of knowledge and the kind of knower that specialises the different professions, and what is valorised and legitimated for each kind of professional. Semantic gravity was used to explore the expected knowledge recontextualisations in diverse and complex clinical settings for each of the professions. Registered professionals who are clinical educators as well as curriculum designers for clinical studies were interviewed. Profession-specific course outlines were further data sources. The biomedical disciplines Anatomy and Physiology were characterised for their measures of distinction and their respective knowledge-knower structures. Analysis traced each discipline from its strongly classified form in autonomous curricula when there were separate learner-cohorts for physiotherapists and occupational therapists, to post-merger when the disciplines were framed as human biology in an integrated foundational curriculum for a joint cohort of students. Curricular documents for the twenty year period were analysed quantitatively and qualitatively to establish the positioning of Physiology and Anatomy before and after the disciplines merged to a single course of Human Biology. Teaching staff were interviewed for their understanding of what specialises the physiological and anatomical components of the Human Biology curriculum, what they considered as powerful knowledge for the professions, and who they envisaged as the ideal student-knower exiting the basic sciences platform to enter more advanced clinical studies. The degree of context-dependence for meaning-making in the different disciplinary domains and the condensation of meanings inherent in the respective practices and contexts, were analysed. The thesis argues that following the merger Anatomy is preferentially legitimated as powerful knowledge at the expense of Physiology; that the ideal of disciplinary integration is not reached, and that the segmental organisation and structuring of the curriculum negatively impacted on cumulative knowledge-building and application of professional knowledge in the clinical arena. After the merger the disciplines lost their shape, and in particular the hierarchical knowledge structure of Physiology collapsed. By not having access to the necessary disciplinary knowledge structures and their associated practices, students' ability for scaffolding and integrating knowledge into the clinical arena was constrained. The organisation of the current Human Biology curriculum does not facilitate cumulative learning, and in so doing may not contribute to the envisaged graduate professional who is required to practice within a complex and demanding healthcare work environment. The significance of this study conveys that interdisciplinary programmes should be carefully considered, and there is an added imperative in the health professions which ultimately realise treatment of patients. If, aside from interdisciplinary teaching, there are also merged cohorts of participant students, then a sound understanding of the epistemic requirements of each profession is required. Those involved in curriculum development in various fields need to take these recommendations into account to enable cumulative learning and enable epistemological access to powerful knowledge for an increasingly diverse student body.
- Full Text:
- Date Issued: 2017
- Authors: De Bie, Gabrielle
- Date: 2017
- Subjects: Medical education -- Curricula , Human anatomy -- Study and teaching -- Curricula , Physiology -- Study and teaching -- Curricula , Occupational therapy -- Study and teaching -- Curricula , Physical therapy -- Study and teaching -- Curricula , Medical rehabilitation -- Study and teaching -- Curricula , Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/18617 , vital:22361
- Description: This study was motivated by the researcher's experience that students in the rehabilitative health professional programmes were finding it difficult to access fundamental knowledge upon which their professional practices and clinical contexts are based. An important focus of the research was the extent to which cumulative knowledge-building was impacted after the foundational biomedical curriculum became an interdisciplinary programme. The study explored whether the organisation of the interdisciplinary foundational curriculum served the fundamental needs of the professions, and whether, as a matter of social justice, students' access to powerful knowledge was enabled by the form that the fundamental curriculum assumed. This curriculum study at a particular Faculty of Health Sciences foregrounds the structuring, organisation and differentiation of disciplinary knowledge, and reflects a twenty year period that included not only transitions in professional education but also extensive transformation in, and a different approach to, health delivery. At the institution, physiology and anatomy, the biomedical sciences basic to the health professions, underwent disciplinary merging and subsequent altered positioning in curricula. Medicine opted for a problem-based learning approach whereas the rehabilitation health sciences did not. Legitimation Code Theory (LCT) provided the means for analysis of the extent to which interdisciplinary organisation in the foundational curriculum for Physiotherapy and Occupational Therapy enabled integrative, cumulative building of knowledge for professional and clinical contexts. Specialisation and Semantics dimensions of Legitimation Code Theory were used to reveal the principles underpinning practices, contexts and dispositions of Anatomy and Physiology at the Faculty of Health Sciences over a twenty year period post democratisation in South Africa (1994 - 2013). Disciplinary positioning in curriculum prior- and post-merger, were compared and contrasted. LCT were used to characterise the distinctiveness of Physiotherapy and Occupational Therapy at the university including the kind of knowledge and the kind of knower that specialises the different professions, and what is valorised and legitimated for each kind of professional. Semantic gravity was used to explore the expected knowledge recontextualisations in diverse and complex clinical settings for each of the professions. Registered professionals who are clinical educators as well as curriculum designers for clinical studies were interviewed. Profession-specific course outlines were further data sources. The biomedical disciplines Anatomy and Physiology were characterised for their measures of distinction and their respective knowledge-knower structures. Analysis traced each discipline from its strongly classified form in autonomous curricula when there were separate learner-cohorts for physiotherapists and occupational therapists, to post-merger when the disciplines were framed as human biology in an integrated foundational curriculum for a joint cohort of students. Curricular documents for the twenty year period were analysed quantitatively and qualitatively to establish the positioning of Physiology and Anatomy before and after the disciplines merged to a single course of Human Biology. Teaching staff were interviewed for their understanding of what specialises the physiological and anatomical components of the Human Biology curriculum, what they considered as powerful knowledge for the professions, and who they envisaged as the ideal student-knower exiting the basic sciences platform to enter more advanced clinical studies. The degree of context-dependence for meaning-making in the different disciplinary domains and the condensation of meanings inherent in the respective practices and contexts, were analysed. The thesis argues that following the merger Anatomy is preferentially legitimated as powerful knowledge at the expense of Physiology; that the ideal of disciplinary integration is not reached, and that the segmental organisation and structuring of the curriculum negatively impacted on cumulative knowledge-building and application of professional knowledge in the clinical arena. After the merger the disciplines lost their shape, and in particular the hierarchical knowledge structure of Physiology collapsed. By not having access to the necessary disciplinary knowledge structures and their associated practices, students' ability for scaffolding and integrating knowledge into the clinical arena was constrained. The organisation of the current Human Biology curriculum does not facilitate cumulative learning, and in so doing may not contribute to the envisaged graduate professional who is required to practice within a complex and demanding healthcare work environment. The significance of this study conveys that interdisciplinary programmes should be carefully considered, and there is an added imperative in the health professions which ultimately realise treatment of patients. If, aside from interdisciplinary teaching, there are also merged cohorts of participant students, then a sound understanding of the epistemic requirements of each profession is required. Those involved in curriculum development in various fields need to take these recommendations into account to enable cumulative learning and enable epistemological access to powerful knowledge for an increasingly diverse student body.
- Full Text:
- Date Issued: 2017
Analysis of a South African cyber-security awareness campaign for schools using interdisciplinary communications frameworks
- Authors: Leppan, Claudette
- Date: 2017
- Subjects: Internet -- Safety measures Computer networks -- Security measures , Mass media and technology Mass media -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18167 , vital:28582
- Description: To provide structure to cyber awareness and educational initiatives in South Africa, Kortjan and Von Solms (2014) developed a five-layer cyber-security awareness and education framework. The purpose of the dissertation is to determine how the framework layers can be refined through the integration of communication theory, with the intention to contribute towards the practical implications of the framework. The study is approached qualitatively and uses a case study for argumentation to illustrate how the existing framework can be further developed. Drawing on several comprehensive campaign planning models, the dissertation illustrates that not all important campaign planning elements are currently included in the existing framework. Proposed changes in the preparation layer include incorporating a situational and target audience analysis, determining resources allocated for the campaign, and formulating a communication strategy. Proposed changes in the delivery layer of the framework are concerned with the implementation, monitoring and adjustment, as well as reporting of campaign successes and challenges. The dissertation builds on, and adds to, the growing literature on the development of campaigns for cyber-security awareness and education aimed at children.
- Full Text:
- Date Issued: 2017
- Authors: Leppan, Claudette
- Date: 2017
- Subjects: Internet -- Safety measures Computer networks -- Security measures , Mass media and technology Mass media -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/18167 , vital:28582
- Description: To provide structure to cyber awareness and educational initiatives in South Africa, Kortjan and Von Solms (2014) developed a five-layer cyber-security awareness and education framework. The purpose of the dissertation is to determine how the framework layers can be refined through the integration of communication theory, with the intention to contribute towards the practical implications of the framework. The study is approached qualitatively and uses a case study for argumentation to illustrate how the existing framework can be further developed. Drawing on several comprehensive campaign planning models, the dissertation illustrates that not all important campaign planning elements are currently included in the existing framework. Proposed changes in the preparation layer include incorporating a situational and target audience analysis, determining resources allocated for the campaign, and formulating a communication strategy. Proposed changes in the delivery layer of the framework are concerned with the implementation, monitoring and adjustment, as well as reporting of campaign successes and challenges. The dissertation builds on, and adds to, the growing literature on the development of campaigns for cyber-security awareness and education aimed at children.
- Full Text:
- Date Issued: 2017
Analysis of factors affecting performance of a low-temperature Organic Rankine Cycle heat engine
- Authors: Kalua, Tisaye Bertram
- Date: 2017
- Subjects: Rankine cycle Heat engineering , Cogeneration of electric power and heat
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/17844 , vital:28460
- Description: Organic Rankine Cycle (ORC) heat engines convert low-grade heat to other forms of energy such as electrical and mechanical energy. They achieve this by vaporizing and expanding the organic fluid at high pressure, turning the turbine which can be employed to run an alternator or any other mechanism as desired. Conventional Rankine Cycles operate with steam at temperatures above 400 ℃. The broad aspect of the research focussed on the generation of electricity to cater for household needs. Solar energy would be used to heat air which would in turn heat rocks in an insulated vessel. This would act as an energy storage in form of heat from which a heat transfer fluid would collect heat to supply the ORC heat engine for the generation of electricity. The objective of the research was to optimize power output of the ORC heat engine operating at temperatures between 25℃ at the condenser and 90 to 150℃ at the heat source. This was achieved by analysis of thermal energy, mechanical power, electrical power and physical parameters in connection with flow rate of working fluid and heat transfer fluids.
- Full Text:
- Date Issued: 2017
- Authors: Kalua, Tisaye Bertram
- Date: 2017
- Subjects: Rankine cycle Heat engineering , Cogeneration of electric power and heat
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/17844 , vital:28460
- Description: Organic Rankine Cycle (ORC) heat engines convert low-grade heat to other forms of energy such as electrical and mechanical energy. They achieve this by vaporizing and expanding the organic fluid at high pressure, turning the turbine which can be employed to run an alternator or any other mechanism as desired. Conventional Rankine Cycles operate with steam at temperatures above 400 ℃. The broad aspect of the research focussed on the generation of electricity to cater for household needs. Solar energy would be used to heat air which would in turn heat rocks in an insulated vessel. This would act as an energy storage in form of heat from which a heat transfer fluid would collect heat to supply the ORC heat engine for the generation of electricity. The objective of the research was to optimize power output of the ORC heat engine operating at temperatures between 25℃ at the condenser and 90 to 150℃ at the heat source. This was achieved by analysis of thermal energy, mechanical power, electrical power and physical parameters in connection with flow rate of working fluid and heat transfer fluids.
- Full Text:
- Date Issued: 2017
Analysis of the Corporate Social Investment motives and benefits behind the sponsors’ involvement with Parkrun South Africa
- Authors: Fordyce, Jonathan
- Date: 2017
- Subjects: Parkrun (Organization) , Parkrun (SA) , Blue Label Telecoms (Firm) , Dis-Chem (Firm) , Discovery Vitality (Firm) , Investments -- Moral and ethical aspects -- South Africa , Sports sponsorship -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/5388 , vital:20919
- Description: This study is a qualitative investigation into the area of Corporate Social Investment (CSI) of non-profit organisations (NPOs). The focus of the study is on the non-profit organisation Parkrun South Africa (Parkrun SA) and its three major sponsors, namely Blue Label Telecoms, Discovery Vitality and Dis-Chem Pharmacies. The research analyses and subsequently posits the various benefits and motivations of the sponsors’ CSI initiative with Parkrun SA. Semi-structured, one-on-one interviews were carried out with the three sponsors to establish these benefits and motivations. The interviewees were selected based on their involvement and influence in establishing and governing their organisations’ CSI initiative with Parkrun SA. The research compared the benefits and motivations, highlighted by the sponsors during the interviews, to the current body of knowledge and literature on CSI. From the interviews it became evident that the benefits and motivations, pertaining to each sponsor, are well aligned to the current literature on CSI benefits and motivations. The benefits and motivations of the three organisations were also deemed very similar. Upon evaluation of the research, it became evident that the most essential motivator for all three sponsoring organisations is commercial. Key to all the sponsoring organisations involvement with Parkrun SA, is the potential return on investment through the various commercial aspects of being associated with such an initiative. Branding was the biggest benefit named by all three sponsoring organisations, however, creating a healthy society emerged as a major benefit too. It can be argued that health has become a major benefit for the sponsors because of the success and exponential growth of Parkrun SA. This growth has captured a large audience and in so doing, created major health benefits for the vast array of participants. Finally, through the data collection and analysis it became clear that the sponsors all view their CSI initiative with Parkrun SA as a major success. It is however, recommended that Parkrun SA start to grow their organisation to match the sustained growth seen in the country. There is a need to expand the organisation in terms of employees and transparent corporate reporting to deal with this growth and keep the sponsors satisfied while also keeping additional sponsors fascinated.
- Full Text:
- Date Issued: 2017
- Authors: Fordyce, Jonathan
- Date: 2017
- Subjects: Parkrun (Organization) , Parkrun (SA) , Blue Label Telecoms (Firm) , Dis-Chem (Firm) , Discovery Vitality (Firm) , Investments -- Moral and ethical aspects -- South Africa , Sports sponsorship -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/5388 , vital:20919
- Description: This study is a qualitative investigation into the area of Corporate Social Investment (CSI) of non-profit organisations (NPOs). The focus of the study is on the non-profit organisation Parkrun South Africa (Parkrun SA) and its three major sponsors, namely Blue Label Telecoms, Discovery Vitality and Dis-Chem Pharmacies. The research analyses and subsequently posits the various benefits and motivations of the sponsors’ CSI initiative with Parkrun SA. Semi-structured, one-on-one interviews were carried out with the three sponsors to establish these benefits and motivations. The interviewees were selected based on their involvement and influence in establishing and governing their organisations’ CSI initiative with Parkrun SA. The research compared the benefits and motivations, highlighted by the sponsors during the interviews, to the current body of knowledge and literature on CSI. From the interviews it became evident that the benefits and motivations, pertaining to each sponsor, are well aligned to the current literature on CSI benefits and motivations. The benefits and motivations of the three organisations were also deemed very similar. Upon evaluation of the research, it became evident that the most essential motivator for all three sponsoring organisations is commercial. Key to all the sponsoring organisations involvement with Parkrun SA, is the potential return on investment through the various commercial aspects of being associated with such an initiative. Branding was the biggest benefit named by all three sponsoring organisations, however, creating a healthy society emerged as a major benefit too. It can be argued that health has become a major benefit for the sponsors because of the success and exponential growth of Parkrun SA. This growth has captured a large audience and in so doing, created major health benefits for the vast array of participants. Finally, through the data collection and analysis it became clear that the sponsors all view their CSI initiative with Parkrun SA as a major success. It is however, recommended that Parkrun SA start to grow their organisation to match the sustained growth seen in the country. There is a need to expand the organisation in terms of employees and transparent corporate reporting to deal with this growth and keep the sponsors satisfied while also keeping additional sponsors fascinated.
- Full Text:
- Date Issued: 2017
Analysis of the impact of Smallholder Irrigation Schemes on the choice of rural livelihood strategy and household food security in Eastern Cape
- Authors: Christian, Mzuyanda
- Date: 2017
- Subjects: Irrigation -- South Africa -- Eastern Cape Farms, Small -- South Africa -- Eastern Cape Food security -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/4813 , vital:28526
- Description: Since the end of Apartheid, the South African government has invested substantially in smallholder irrigation schemes, particularly in the former homeland areas. One of the primary goals for establishment of these schemes was to solve food security problems. Sadly, these efforts have not produced the desired results, and poverty has deepened. The question that can be asked is: What is it that makes South African smallholder agricultural sector seemingly impervious to the interventions that government has made in targeting smallholder farmers since the dawn of democracy in 1994? In order to address such a question, a set of structured questionnaires was used to interview 100 smallholder irrigators and 100 non-irrigators using multistage stratified random sampling technique in the Amatole, Chris Hani and OR Tambo District municipalities. Demographic and socio-economic characteristics of smallholder irrigators and non-irrigators around Qamata, Pendu, Tyhefu, Merelles and Ntshongweni irrigation schemes were measured using descriptive statistics. Profitability between the two groups was measured using gross margin analysis (GM). The Probit model was used to determine the factors that affect smallholder farmer‘s choice of participation in irrigation schemes. The impact of irrigation participation on yields, crop sales and food security was estimated using the propensity score matching (PSM) technique. The impact of irrigation participation of smallholder farmer‘s choice of livelihood strategy was estimated using the multinomial regression model. The results showed that male respondents were dominant with a representation of 63 percent and average mean household size of 4 persons with the household head having spent at least 7 years at school. Farming was found to be the major (64 percent) occupation in the study area with an average income of R2 944.52 per cropping season. Both irrigating and non-irrigating smallholder farmers in the study area used improved, fertilizer and tractor for production. Overall, smallholder farmers spent 30.9 percent of their household income on food with irrigators‘food spending lower than those of non-irrigators. The gross margin analysis suggests that the irrigated farmers were in a better position to afford enough food in order to satisfy their household requirement. Findings from the Probit regression and Propensity Score Matching are consistent across the methods, indicating that irrigation participation has a positive influence on crop yields, income and consumption expenditure. Probit regression further showed that age, quality of land, access to credit, access to market, distance to the scheme and membership of another society/association have a positive impact on access and use of irrigation and are significant at p < 0.05 percent level. The Propensity Score Matching using Nearest Neighbour and Kernel Matching Methods of the outcome variables, total farm income and food consumption patterns, shows a positive and statistically significant result at p < 0.05 percent level. The nearest neighbour matching method shows that irrigators received higher farm income R2044.01 than non-irrigating farmers R622.12. The Average Treatment Effect on total food expenditure was negative both in the case of NNM and KM algorithms, indicating that participation in irrigation can decrease the expenditure levels on food from R933.30 to R926.70. This could be due to the fact that irrigating farmers produced enough for home consumption than non-irrigators. The multinomial regression model shows that irrigation participation influences smallholder farmers choice of livelihood strategy and these variables were statistically significant at p < 0.05 percent level. These results provide insights to address the question as to the appropriate development path for transition from homestead to irrigation. Continued support to smallholder farmers in the forms of funding, extension services and improved technologies is certainly needed to enhance food security.
- Full Text:
- Date Issued: 2017
- Authors: Christian, Mzuyanda
- Date: 2017
- Subjects: Irrigation -- South Africa -- Eastern Cape Farms, Small -- South Africa -- Eastern Cape Food security -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/4813 , vital:28526
- Description: Since the end of Apartheid, the South African government has invested substantially in smallholder irrigation schemes, particularly in the former homeland areas. One of the primary goals for establishment of these schemes was to solve food security problems. Sadly, these efforts have not produced the desired results, and poverty has deepened. The question that can be asked is: What is it that makes South African smallholder agricultural sector seemingly impervious to the interventions that government has made in targeting smallholder farmers since the dawn of democracy in 1994? In order to address such a question, a set of structured questionnaires was used to interview 100 smallholder irrigators and 100 non-irrigators using multistage stratified random sampling technique in the Amatole, Chris Hani and OR Tambo District municipalities. Demographic and socio-economic characteristics of smallholder irrigators and non-irrigators around Qamata, Pendu, Tyhefu, Merelles and Ntshongweni irrigation schemes were measured using descriptive statistics. Profitability between the two groups was measured using gross margin analysis (GM). The Probit model was used to determine the factors that affect smallholder farmer‘s choice of participation in irrigation schemes. The impact of irrigation participation on yields, crop sales and food security was estimated using the propensity score matching (PSM) technique. The impact of irrigation participation of smallholder farmer‘s choice of livelihood strategy was estimated using the multinomial regression model. The results showed that male respondents were dominant with a representation of 63 percent and average mean household size of 4 persons with the household head having spent at least 7 years at school. Farming was found to be the major (64 percent) occupation in the study area with an average income of R2 944.52 per cropping season. Both irrigating and non-irrigating smallholder farmers in the study area used improved, fertilizer and tractor for production. Overall, smallholder farmers spent 30.9 percent of their household income on food with irrigators‘food spending lower than those of non-irrigators. The gross margin analysis suggests that the irrigated farmers were in a better position to afford enough food in order to satisfy their household requirement. Findings from the Probit regression and Propensity Score Matching are consistent across the methods, indicating that irrigation participation has a positive influence on crop yields, income and consumption expenditure. Probit regression further showed that age, quality of land, access to credit, access to market, distance to the scheme and membership of another society/association have a positive impact on access and use of irrigation and are significant at p < 0.05 percent level. The Propensity Score Matching using Nearest Neighbour and Kernel Matching Methods of the outcome variables, total farm income and food consumption patterns, shows a positive and statistically significant result at p < 0.05 percent level. The nearest neighbour matching method shows that irrigators received higher farm income R2044.01 than non-irrigating farmers R622.12. The Average Treatment Effect on total food expenditure was negative both in the case of NNM and KM algorithms, indicating that participation in irrigation can decrease the expenditure levels on food from R933.30 to R926.70. This could be due to the fact that irrigating farmers produced enough for home consumption than non-irrigators. The multinomial regression model shows that irrigation participation influences smallholder farmers choice of livelihood strategy and these variables were statistically significant at p < 0.05 percent level. These results provide insights to address the question as to the appropriate development path for transition from homestead to irrigation. Continued support to smallholder farmers in the forms of funding, extension services and improved technologies is certainly needed to enhance food security.
- Full Text:
- Date Issued: 2017
Analysis of the reliability for the 132/66/22 KV distribution network within ESKOM’s Eastern Cape operating unit
- Authors: Pantshwa, Athini
- Date: 2017
- Subjects: Electric power distribution Electricity -- Supply -- Engineering , Smart power grids
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/19750 , vital:28953
- Description: A stable and reliable electrical power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customer’s reliability requirements are met and that the regulators requirements are satisfied at the lowest possible cost. It is known fact around the world that 90% of the customer service interruptions are caused due to failure in distribution system. Therefore, it is worth considering reliability assessments as it provides an opportunity to incorporate the cost or losses incurred by the utilities customer as a result of power failure. This must be considered in the planning and operating practices. The system modelling and simulation study is carried out on one of the district’s distribution system which consists of 132 kV, 66 kV and 22 kV network in Aliwal North Sector ECOU. The reliability assessment is done on the 22, 66 and 132 kV system to assess the performance of the present system and also predictive reliability analysis for the future system considering load growth and system expansion. The alternative which gives low SAIDI, SAIFI and minimum breakeven costs is being assessed and considered. The reliability of 132 kV system could be further improved by constructing a new 132 kV line from a different source of supply and connecting with line coming from another district (reserve) at reasonable break even cost. The decision base could be further improved by having Aliwal North Sector context interruption cost. However, the historical data which may be used in Aliwal North Sector to acquire interruption costs from the customers are being proposed. The focus should be on improving the power quality on constrained networks first, then the reliability. Therefore for the Aliwal North power system network it is imperative that Eskom invest on the reliability of this network. This dissertation also analysed load reflected economic benefit versus performance expectations that should be optimized through achieving a balance between network performance (SAIDI) improvement, and total life cycle cost (to Eskom as well as the economy). Reliability analysis conducted in this dissertation used Aliwal North power system network as a case study; the results proved that the system is vulnerable to faults, planned and unplanned outages. Reliability evaluation studies were conducted on the system using DigSilent software in conjunction with FME. These two models gave accurate results with acceptable variance in most indices except for the ENS where the variance was quite significant. It can be concluded that DigSilent results are the most accurate results in all three reliability evaluation scenarios for the Aliwal North Power System, best interpretation being that of DigSilent.
- Full Text:
- Date Issued: 2017
- Authors: Pantshwa, Athini
- Date: 2017
- Subjects: Electric power distribution Electricity -- Supply -- Engineering , Smart power grids
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/19750 , vital:28953
- Description: A stable and reliable electrical power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customer’s reliability requirements are met and that the regulators requirements are satisfied at the lowest possible cost. It is known fact around the world that 90% of the customer service interruptions are caused due to failure in distribution system. Therefore, it is worth considering reliability assessments as it provides an opportunity to incorporate the cost or losses incurred by the utilities customer as a result of power failure. This must be considered in the planning and operating practices. The system modelling and simulation study is carried out on one of the district’s distribution system which consists of 132 kV, 66 kV and 22 kV network in Aliwal North Sector ECOU. The reliability assessment is done on the 22, 66 and 132 kV system to assess the performance of the present system and also predictive reliability analysis for the future system considering load growth and system expansion. The alternative which gives low SAIDI, SAIFI and minimum breakeven costs is being assessed and considered. The reliability of 132 kV system could be further improved by constructing a new 132 kV line from a different source of supply and connecting with line coming from another district (reserve) at reasonable break even cost. The decision base could be further improved by having Aliwal North Sector context interruption cost. However, the historical data which may be used in Aliwal North Sector to acquire interruption costs from the customers are being proposed. The focus should be on improving the power quality on constrained networks first, then the reliability. Therefore for the Aliwal North power system network it is imperative that Eskom invest on the reliability of this network. This dissertation also analysed load reflected economic benefit versus performance expectations that should be optimized through achieving a balance between network performance (SAIDI) improvement, and total life cycle cost (to Eskom as well as the economy). Reliability analysis conducted in this dissertation used Aliwal North power system network as a case study; the results proved that the system is vulnerable to faults, planned and unplanned outages. Reliability evaluation studies were conducted on the system using DigSilent software in conjunction with FME. These two models gave accurate results with acceptable variance in most indices except for the ENS where the variance was quite significant. It can be concluded that DigSilent results are the most accurate results in all three reliability evaluation scenarios for the Aliwal North Power System, best interpretation being that of DigSilent.
- Full Text:
- Date Issued: 2017
Ant colony optimisation-based algorithms for optical burst switching networks
- Gravett, Andrew Scott, Gibbon, Timothy B
- Authors: Gravett, Andrew Scott , Gibbon, Timothy B
- Date: 2017
- Subjects: Distributed algorithms , Ants -- Behavior -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18939 , vital:28757
- Description: This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments.
- Full Text:
- Date Issued: 2017
- Authors: Gravett, Andrew Scott , Gibbon, Timothy B
- Date: 2017
- Subjects: Distributed algorithms , Ants -- Behavior -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/18939 , vital:28757
- Description: This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments.
- Full Text:
- Date Issued: 2017
Anti-fetishism: parodying the depiction of the female body as fetish
- Authors: Pirie, René Alexis
- Date: 2017
- Subjects: Body image -- Social aspects Fashion -- Social aspects
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/20377 , vital:29272
- Description: sexual objectification of women is widespread in contemporary lifestyle and fashion magazines. Models used for advertising purposes often set a standard of beauty and youth that is unrealistic and limiting. This standard has damaging effects on women’s sense of self and their societal behaviour. Such images not only sexualise as well as fetishise women’s bodies, but also encourage self-surveillance. This research study examines Cindy Sherman, Sarah Lucas, Louise Bourgeois and Ángela Burón’s artistic responses to fetishized images of women, in order to assess what artistic strategies could be used to oppose such images in magazine advertisements. It aims to identify what anti-fetishism involves in theory and practice and to use this information to formulate an anti-fetish strategy which informs a series of anti-fetish artworks. The purpose of this series of works is to oppose the fetishization of women, particularly in magazine advertisements of high-end consumer products. The study contributes to the discourse of anti-fetishism and addresses a knowledge gap since research on anti-fetishism has much room for development. It is a Qualitative research study which adhered to a Practice-based research method. The key findings of this study are that anti-fetishism and female fetishism are approaches that differ from one another yet also overlap. Furthermore, Anti-fetishism involves the use of parodic mockery, while female fetishism is concerned mostly with undecidability as a strategy. From the examination of the artists, the anti-fetishistic strategy of parody, largely influenced the practical component of this research study. Parody offers a clear opposition to the still widespread fetishization of women in magazines both in South Africa and other Westernized countries across the world.
- Full Text:
- Date Issued: 2017
- Authors: Pirie, René Alexis
- Date: 2017
- Subjects: Body image -- Social aspects Fashion -- Social aspects
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/20377 , vital:29272
- Description: sexual objectification of women is widespread in contemporary lifestyle and fashion magazines. Models used for advertising purposes often set a standard of beauty and youth that is unrealistic and limiting. This standard has damaging effects on women’s sense of self and their societal behaviour. Such images not only sexualise as well as fetishise women’s bodies, but also encourage self-surveillance. This research study examines Cindy Sherman, Sarah Lucas, Louise Bourgeois and Ángela Burón’s artistic responses to fetishized images of women, in order to assess what artistic strategies could be used to oppose such images in magazine advertisements. It aims to identify what anti-fetishism involves in theory and practice and to use this information to formulate an anti-fetish strategy which informs a series of anti-fetish artworks. The purpose of this series of works is to oppose the fetishization of women, particularly in magazine advertisements of high-end consumer products. The study contributes to the discourse of anti-fetishism and addresses a knowledge gap since research on anti-fetishism has much room for development. It is a Qualitative research study which adhered to a Practice-based research method. The key findings of this study are that anti-fetishism and female fetishism are approaches that differ from one another yet also overlap. Furthermore, Anti-fetishism involves the use of parodic mockery, while female fetishism is concerned mostly with undecidability as a strategy. From the examination of the artists, the anti-fetishistic strategy of parody, largely influenced the practical component of this research study. Parody offers a clear opposition to the still widespread fetishization of women in magazines both in South Africa and other Westernized countries across the world.
- Full Text:
- Date Issued: 2017
Anti-malarial synergy of secondary metabolites from Morinda lucida Benth.
- Lakkakula, Jaya R, Matshaya, Thabo, Krause, Rui W M
- Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125609 , vital:35800 , https://doi.org/10.1016/j.msec.2016.08.073
- Description: Ethnopharmacological relevance The roots, stem and leaves of Morinda lucida are used in some African countries as treatment against different types of fevers including yellow fever, malaria, trypanosomiasis and feverish conditions during child birth. Aim of the study To determine the in vitro cell toxicity and anti-malarial activity of the extracts of stem bark of M. lucida and to identify the secondary metabolites in the extract that may be responsible for this activity. Materials and methods The cell toxicity studies of crude extract [dichloromethane (DCM): Methanol (MeOH) in a ratio of1:1 (v/v)] as well as compounds isolated from the same extract were carried out using human cervix adenocarcinoma cells (HeLa cells); while the anti-malarial activities of the same samples were performed against Plasmodium falciparum strain 3D7 using the parasite lactate dehydrogenase (pLDH) assay. The isolation of the active compounds was carried out using chromatographic techniques (column and thin layer chromatography) where as mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses were employed in the characterisation and identification of the isolated secondary metabolites. Results The pLDH and cell toxicity assays for the crude extract and the fractions of M. lucida indicated that some fractions reduced the malaria parasite viability by approximately 50% at 100 μg/mL and they were not significantly cytotoxic. An IC50 done on the crude extract gave a value of 25 μg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Seven chemical constituents i.e. asperuloside (1), asperulosidic acid (2), stigmasterol (3a), β-sitosterol (3b), cycloartenol (3c), campesterol (3d) and 5,15-O-dimethylmorindol (4) were isolated from the DCM-MeOH extract of stem bark. The isolated compounds tested were not that active by themselves individually at 20 μM but their activities were increased when the isolated compounds were combined. As seen when compounds 2, 3 and 4 (% viability: 93, 123 and 101 respectively) were combined yielding an IC50 value of 17 μM. Furthermore, this is the first report of compounds 1, 2, 3c, 3d and 4 isolated from M. lucida. Conclusion The crude extract completely suppressed the growth of P. falciparum. This indicates that the crude extract contains many compounds that might be acting in synergy. The observed activity of the crude extract and the samples containing a mixture of different compounds support the traditional use of M. lucida for the treatment of malaria.
- Full Text:
- Date Issued: 2017
- Authors: Lakkakula, Jaya R , Matshaya, Thabo , Krause, Rui W M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125609 , vital:35800 , https://doi.org/10.1016/j.msec.2016.08.073
- Description: Ethnopharmacological relevance The roots, stem and leaves of Morinda lucida are used in some African countries as treatment against different types of fevers including yellow fever, malaria, trypanosomiasis and feverish conditions during child birth. Aim of the study To determine the in vitro cell toxicity and anti-malarial activity of the extracts of stem bark of M. lucida and to identify the secondary metabolites in the extract that may be responsible for this activity. Materials and methods The cell toxicity studies of crude extract [dichloromethane (DCM): Methanol (MeOH) in a ratio of1:1 (v/v)] as well as compounds isolated from the same extract were carried out using human cervix adenocarcinoma cells (HeLa cells); while the anti-malarial activities of the same samples were performed against Plasmodium falciparum strain 3D7 using the parasite lactate dehydrogenase (pLDH) assay. The isolation of the active compounds was carried out using chromatographic techniques (column and thin layer chromatography) where as mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses were employed in the characterisation and identification of the isolated secondary metabolites. Results The pLDH and cell toxicity assays for the crude extract and the fractions of M. lucida indicated that some fractions reduced the malaria parasite viability by approximately 50% at 100 μg/mL and they were not significantly cytotoxic. An IC50 done on the crude extract gave a value of 25 μg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Seven chemical constituents i.e. asperuloside (1), asperulosidic acid (2), stigmasterol (3a), β-sitosterol (3b), cycloartenol (3c), campesterol (3d) and 5,15-O-dimethylmorindol (4) were isolated from the DCM-MeOH extract of stem bark. The isolated compounds tested were not that active by themselves individually at 20 μM but their activities were increased when the isolated compounds were combined. As seen when compounds 2, 3 and 4 (% viability: 93, 123 and 101 respectively) were combined yielding an IC50 value of 17 μM. Furthermore, this is the first report of compounds 1, 2, 3c, 3d and 4 isolated from M. lucida. Conclusion The crude extract completely suppressed the growth of P. falciparum. This indicates that the crude extract contains many compounds that might be acting in synergy. The observed activity of the crude extract and the samples containing a mixture of different compounds support the traditional use of M. lucida for the treatment of malaria.
- Full Text:
- Date Issued: 2017
Antibacterial activities of both combined and individual medicinal plants extracts traditionally used to treat pneumonia
- Authors: Mhango, Immaculate
- Date: 2017
- Subjects: Antibacterial agents , Pneumonia -- Treatment
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/19762 , vital:28959
- Description: Pneumonia is one of the five major leading causes of death in children under-fives years and the elderly worldwide. Antibiotics used for its treatment are less potent due to bacteria development of bacteria resistant to antibiotics. This has led to a surge in search of novel drugs. There are already some drugs in clinical use that have natural products and derivatives such as quinine, morphine, vincristine, and taxol among others. The healing value of medicinal plants has been well accepted since Stone Age across the globe. This plant therapy has been prescribed and prepared independently or in combination. The following plants: Terminalia sericea, Warburgia salutaris, Dodonea angustofolia, Eucalyptus camaldulensis, Ballota africana, Kigelia africana and Acorus gramineus. These plants are most commonly used for treatment of pneumonia and other ailment, were studied to validate their antimicrobial activity based on scientific determination. The primary aim of this study was to evaluate the efficacy of these plants against bacteria pneumonia pathogens. Seven medicinal plants, independently and in combinations were relatively analysed for their antimicrobial activity against Staphylococcus aureus, Streptococcus pyogenes, and Klebsiella pneumoniae. Ground plant material of roots, bark and leafs were prepared with acetone, ethanol and distilled water. Dimethyl sulfoxide (10 &100%) was used as a reconstitution solvent and ciprofloxacin (10 %) as a positive control. The antimicrobial efficacy was determined using agar well diffusion and microtiter plate methods. Interaction between plants was evaluated by calculating fraction inhibitory concentration index (ΣFIC). Noteworthy activity for individual studies with all test organisms was observed with T. sericea. However, highest ZOI (30 mm) was observed for B. africana ethanol extract for S. pyogenes. Weak microbial activity was noted in W. salutaris and D. angustofolia extracts with all test organisms. Good antimicrobial activity was observed in combination studies with all organisms. The potency of different plant combinations varied with highest ZOI observed with B. africana and W. salutaris ranging from 33-35 mm, conversely ZOI of 35 mm was also noted for S. aureus in B. africana and E. camaldulensis ethanol extract. Noteworthy antimicrobial activity was observed in T. sericea and D. angustofolia against all test pathogens. weak antimicrobial activity with highest MICs was observed in combinations where W. salutaris was involved. After calculating ΣFICs, strongest synergistic effect was displayed for W. salutaris and D. angustofolia against all test organisms (lowest ΣFICs 0.0491). Most plant extract combinations, displayed either synergistic, additive or indifferent effect, with few demonstrating antagonistic interactions. Significant antagonism effect was noted for S. pyogenes with T. sericea ethanol extract ΣFIC value of 15.51. Based on results of this study use of plants in combination increase antimicrobial efficacy. The antimicrobial activities; synergistic and additive effects observed adds credibility in the use of plant combination for therapeutic value in treatment of pneumonia. Future studies are recommended to identify and isolate specific active compounds involved in plant combination interactions. The importance of combination studies for possible development of new antimicrobials that can succumb bacterial resistance need to be highlighted.
- Full Text:
- Date Issued: 2017
- Authors: Mhango, Immaculate
- Date: 2017
- Subjects: Antibacterial agents , Pneumonia -- Treatment
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/19762 , vital:28959
- Description: Pneumonia is one of the five major leading causes of death in children under-fives years and the elderly worldwide. Antibiotics used for its treatment are less potent due to bacteria development of bacteria resistant to antibiotics. This has led to a surge in search of novel drugs. There are already some drugs in clinical use that have natural products and derivatives such as quinine, morphine, vincristine, and taxol among others. The healing value of medicinal plants has been well accepted since Stone Age across the globe. This plant therapy has been prescribed and prepared independently or in combination. The following plants: Terminalia sericea, Warburgia salutaris, Dodonea angustofolia, Eucalyptus camaldulensis, Ballota africana, Kigelia africana and Acorus gramineus. These plants are most commonly used for treatment of pneumonia and other ailment, were studied to validate their antimicrobial activity based on scientific determination. The primary aim of this study was to evaluate the efficacy of these plants against bacteria pneumonia pathogens. Seven medicinal plants, independently and in combinations were relatively analysed for their antimicrobial activity against Staphylococcus aureus, Streptococcus pyogenes, and Klebsiella pneumoniae. Ground plant material of roots, bark and leafs were prepared with acetone, ethanol and distilled water. Dimethyl sulfoxide (10 &100%) was used as a reconstitution solvent and ciprofloxacin (10 %) as a positive control. The antimicrobial efficacy was determined using agar well diffusion and microtiter plate methods. Interaction between plants was evaluated by calculating fraction inhibitory concentration index (ΣFIC). Noteworthy activity for individual studies with all test organisms was observed with T. sericea. However, highest ZOI (30 mm) was observed for B. africana ethanol extract for S. pyogenes. Weak microbial activity was noted in W. salutaris and D. angustofolia extracts with all test organisms. Good antimicrobial activity was observed in combination studies with all organisms. The potency of different plant combinations varied with highest ZOI observed with B. africana and W. salutaris ranging from 33-35 mm, conversely ZOI of 35 mm was also noted for S. aureus in B. africana and E. camaldulensis ethanol extract. Noteworthy antimicrobial activity was observed in T. sericea and D. angustofolia against all test pathogens. weak antimicrobial activity with highest MICs was observed in combinations where W. salutaris was involved. After calculating ΣFICs, strongest synergistic effect was displayed for W. salutaris and D. angustofolia against all test organisms (lowest ΣFICs 0.0491). Most plant extract combinations, displayed either synergistic, additive or indifferent effect, with few demonstrating antagonistic interactions. Significant antagonism effect was noted for S. pyogenes with T. sericea ethanol extract ΣFIC value of 15.51. Based on results of this study use of plants in combination increase antimicrobial efficacy. The antimicrobial activities; synergistic and additive effects observed adds credibility in the use of plant combination for therapeutic value in treatment of pneumonia. Future studies are recommended to identify and isolate specific active compounds involved in plant combination interactions. The importance of combination studies for possible development of new antimicrobials that can succumb bacterial resistance need to be highlighted.
- Full Text:
- Date Issued: 2017
Antidiabetic activity and mechanism of action of extracts of Brachylaena elliptica (Thurb.) DC. and Brachylaena ilicifolia (Lam) Phill & Schweick
- Authors: Sagbo, Idowu Jonas
- Date: 2017
- Subjects: Herbs -- Therapeutic use Pharmacognosy Diabetes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8154 , vital:31624
- Description: International Diabetes Federation (IDF) estimated that there are 415 million people globally that are suffering from diabetes and this figure is likely to double by 2040. In South Africa, the number of people suffering from diabetes is believed to be rising steadily and the current antidiabetic therapies include the use of expensive pharmaceutical drugs which after display numerous adverse side effects. Herbal medicine is an alternative treatment strategy used by many rural populations for the management of diabetes, which is cost-effective and with minimal reported side effects. The aim of this study was to validate the antidiabetic activity and to elucidate the possible mechanisms of action of the aqueous leaf extracts prepared from two plants, Brachylaena elliptica and Brachylaena ilicifolia, used by traditional healers in the Eastern Cape, South Africa for the treatment of diabetes. The current pharmaceutical drugs target site, including carbohydrate digestion, regulation of blood glucose levels through insulin levels or activating glucose uptake in liver and muscle. The plants extracts were therefore evaluated for their potential to mimic or replace these drugs. The inhibibitory effects on alpha amylase, alpha glucosidase, DPP-IV activity and pancreatic lipase were evaluated at various concentrations of the plant extracts. To evaluate the suitability of these extracts for cell based in vitro assay as well as to determine the safety of the plant extracts for human consumption, cytotoxicity towards HepG2 cells was assessed using the MTT assay. The effect of both plant extracts on glucose uptake in HepG2 and L6 cells, lipid accumulation in 3T3-L1 preadipocytes and NO production in RAW macrophages were investigated. Both plant extracts were also tested for INS-1 proliferation using the imageXpress®Micro XLS analysis. The MTT reduction assay was also used to investigate the effect of extracts on INS-1 glucose metabolism and as a reflection of insulin secretion. The inhibitory activity of the crude extracts of both plants on protein glycation, collagenase activity and CYP3A4 interaction were also evaluated The crude extracts of both plants displayed no significant inhibition on alpha amylase, alpha glucosidase, dipeptidyl peptidase-IV, lipase, protein glycation and collagenase compared to relevant standard inhibitors, acarbose, EGCG, Diprotin A, Orlistart and aminoguanidine. The mild inhibition of B. elliptica on alpha glucosidase activity at the highest concentration of the extract tested, was considered as not physiologically relevant. The aqueous extracts of bothplants showed < 40 percent cell death in HepG2 cells even at high concentration and hence support the use of the plants by traditional healers. The extracts of B. ellipticaat 25 µg/ml, displayed a proliferative effect on INS-1 cells when compared to the negative control and B. ilicifolia at 25 μg/ml. The treatment of HepG2 cells with 100 µg/mlB. elliptica and B. ilicifolia extracts revealed a higher glucose uptake of 121 percent and 123 percent respectively when compared to the pharmaceutical drug berberine. However, both plants extracts displayed weak significant glucose uptake in L6 muscle cell line at all the tested concentrations when compared to insulin at 6 μg/ml. The crude extracts of both plants demonstrated no significant effect on 3T3-L1 lipid accumulation and INS-1 glucose metabolism. The extracts of both plants strongly reduced NO production in RAW macrophages at the highest concentration (100 μg/ml) tested in this study, which at least in part, may be explained by the flavanoids and phenols content of these plants. In addition, the crude extracts of both plants displayed weak significant inhibition on the CYP3A4 activity indicating that both plant extracts do not interfere with the cytochrome P450 activation or metabolism of anti-diabetic drugs, that may be taken together with the plant extracts. In conclusion, the results obtained from this study revealed that both plants could possibly exert their hypoglycemic effect via interactions with insulin receptor, thereby enhancing glucose metabolism as well as maintaining and repairing the health state and function of the pancreatic beta cells. The findings in this study, therefore provide evidence that B. elliptica and B. ilicifolia possess antidiabetic properties, and support their folkloric use for the management of diabetes. However, due to the potential toxicity of both plant extracts, they must be prescribed with caution.
- Full Text:
- Date Issued: 2017
- Authors: Sagbo, Idowu Jonas
- Date: 2017
- Subjects: Herbs -- Therapeutic use Pharmacognosy Diabetes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8154 , vital:31624
- Description: International Diabetes Federation (IDF) estimated that there are 415 million people globally that are suffering from diabetes and this figure is likely to double by 2040. In South Africa, the number of people suffering from diabetes is believed to be rising steadily and the current antidiabetic therapies include the use of expensive pharmaceutical drugs which after display numerous adverse side effects. Herbal medicine is an alternative treatment strategy used by many rural populations for the management of diabetes, which is cost-effective and with minimal reported side effects. The aim of this study was to validate the antidiabetic activity and to elucidate the possible mechanisms of action of the aqueous leaf extracts prepared from two plants, Brachylaena elliptica and Brachylaena ilicifolia, used by traditional healers in the Eastern Cape, South Africa for the treatment of diabetes. The current pharmaceutical drugs target site, including carbohydrate digestion, regulation of blood glucose levels through insulin levels or activating glucose uptake in liver and muscle. The plants extracts were therefore evaluated for their potential to mimic or replace these drugs. The inhibibitory effects on alpha amylase, alpha glucosidase, DPP-IV activity and pancreatic lipase were evaluated at various concentrations of the plant extracts. To evaluate the suitability of these extracts for cell based in vitro assay as well as to determine the safety of the plant extracts for human consumption, cytotoxicity towards HepG2 cells was assessed using the MTT assay. The effect of both plant extracts on glucose uptake in HepG2 and L6 cells, lipid accumulation in 3T3-L1 preadipocytes and NO production in RAW macrophages were investigated. Both plant extracts were also tested for INS-1 proliferation using the imageXpress®Micro XLS analysis. The MTT reduction assay was also used to investigate the effect of extracts on INS-1 glucose metabolism and as a reflection of insulin secretion. The inhibitory activity of the crude extracts of both plants on protein glycation, collagenase activity and CYP3A4 interaction were also evaluated The crude extracts of both plants displayed no significant inhibition on alpha amylase, alpha glucosidase, dipeptidyl peptidase-IV, lipase, protein glycation and collagenase compared to relevant standard inhibitors, acarbose, EGCG, Diprotin A, Orlistart and aminoguanidine. The mild inhibition of B. elliptica on alpha glucosidase activity at the highest concentration of the extract tested, was considered as not physiologically relevant. The aqueous extracts of bothplants showed < 40 percent cell death in HepG2 cells even at high concentration and hence support the use of the plants by traditional healers. The extracts of B. ellipticaat 25 µg/ml, displayed a proliferative effect on INS-1 cells when compared to the negative control and B. ilicifolia at 25 μg/ml. The treatment of HepG2 cells with 100 µg/mlB. elliptica and B. ilicifolia extracts revealed a higher glucose uptake of 121 percent and 123 percent respectively when compared to the pharmaceutical drug berberine. However, both plants extracts displayed weak significant glucose uptake in L6 muscle cell line at all the tested concentrations when compared to insulin at 6 μg/ml. The crude extracts of both plants demonstrated no significant effect on 3T3-L1 lipid accumulation and INS-1 glucose metabolism. The extracts of both plants strongly reduced NO production in RAW macrophages at the highest concentration (100 μg/ml) tested in this study, which at least in part, may be explained by the flavanoids and phenols content of these plants. In addition, the crude extracts of both plants displayed weak significant inhibition on the CYP3A4 activity indicating that both plant extracts do not interfere with the cytochrome P450 activation or metabolism of anti-diabetic drugs, that may be taken together with the plant extracts. In conclusion, the results obtained from this study revealed that both plants could possibly exert their hypoglycemic effect via interactions with insulin receptor, thereby enhancing glucose metabolism as well as maintaining and repairing the health state and function of the pancreatic beta cells. The findings in this study, therefore provide evidence that B. elliptica and B. ilicifolia possess antidiabetic properties, and support their folkloric use for the management of diabetes. However, due to the potential toxicity of both plant extracts, they must be prescribed with caution.
- Full Text:
- Date Issued: 2017
Antidiabetic and toxicological properties of Dianthus thunbergii (Caryophyllaceae) roots and Hypoxis argentea (Hypoxidaceae) corms
- Authors: Akinrinde, Akinleye Stephen
- Date: 2017
- Subjects: Medicinal plants--South Africa--Eastern Cape Traditional medicine--South Africa--Eastern Cape Diabetics--Alternative treatment--South Africa
- Language: English
- Type: Thesis , Doctoral , Biochemistry
- Identifier: http://hdl.handle.net/10353/16036 , vital:40606
- Description: Diabetes mellitus is a chronic metabolic disorder primarily characterized by elevated blood glucose levels. Its rapidly increasing prevalence as a major non-communicable disease is now a growing concern for both developed and developing countries. The development of safe, cost-effective and pharmacologically-effective medications continues to a major challenge of antidiabetic management. Since most conventional antidiabetic drugs are costly and present with numerous adverse effects, alternatives are increasingly being sought from natural sources, most notably medicinal plants, as viable approaches to tackling the scourge of this disease. In the Eastern Cape Province of South Africa, the roots of Dianthus thunbergii and corms of Hypoxis argentea are frequently used traditionally for the treatment of diabetes mellitus, although no scientific evidence exists to validate their effectiveness for diabetes management. The studies conducted in the resent research were, therefore, aimed at investigating the antidiabetic and toxicological properties of these plants, in an attempt to providing data towards validating their use in traditional management of diabetes mellitus. Aqueous and ethanol extracts of the underground parts of D. thunbergii and H. argentea were initially subjected to analysis of their phytochemical composition, relative to standard compounds, and the nature of their in-vitro antioxidant activities using standard spectrophotometric methods. The potentials of these extracts for cytotoxicity and/or cell proliferation were evaluated using MTT assay in HepG2 cells and Crystal violet assay in INS-1 cells. These activities were further examined in INS-1 cells using live cell fluorescence imaging techniques. To evaluate the antidiabetic properties of the extracts, they were screened for their inhibitory effects on the activities of different enzymes including α-amylase, α-glucosidase, porcine pancreatic lipase, Dipeptidyl peptidase IV (DPP-IV), collagenase and the drug metabolizing enzyme, CYP3A4, while also assessing their effects on protein glycation using in- vitro visible and fluorescence spectrophotometric approaches. Cell culture procedures were carried out to evaluate the effects of the extracts on glucose utilization in HepG2 cells and L6 myotubes; nitric oxide production in RAW 264.7 macrophages; glucose metabolism in INS-1 cells, as well as triglyceride accumulation in 3T3-L1 pre-adipocytes. Furthermore, identification of compounds present in the aqueous and ethanol extracts was carried out by Liquid chromatography- Mass spectrometry (LC-MS), while volatile oils extracted from fresh and dried parts of the two plants by hydrodistillation were also analyzed by Gas chromatography-Mass spectrometry (GC-MS). The ethanol extracts of both D. thunbergii and H. argentea contained higher amounts of total phenols, flavonoids, tannins, proanthocyanidins and alkaloids, when compared with the aqueous extracts. This finding was in direct correlation with the antioxidant activities of the extracts, with the ethanol extracts of both plants demonstrating stronger scavenging activities against hydrogen peroxide, nitric oxide, ABTS and DPPH radicals, while also exhibiting higher ferric reducing antioxidant potentials, when compared with the aqueous extracts, and in some cases, the standard antioxidants, Vitamin C, butylated hydroxytoluene and rutin. The aqueous extracts of D. thunbergii exhibited the highest toxicity in HepG2 cells with IC50 < 50 μg/ml, while also producing a concentration-dependent reduction in the viability of INS-1 cells up to 41.81percent at 50 μg/ml. Both extracts of H. argentea, however, did not produce any significant toxicity in these cells. Fluorescence imaging of live INS-1 cells using Hoechst and propidium iodide staining revealed stimulation of cell proliferation by H. argentea, while the cytotoxicity of D. thunbergii was further confirmed. H. argentea caused stimulation of glucose uptake in HepG2 cells up to 119.58 percent at 100 μg/ml and as much as 116.96 percent in L6 myotubes at 50 μg/ml, without showing toxicity to these cells. D. thunbergii produced 18.39 percent increase in L6 glucose uptake above untreated control; although its effect on HepG2 glucose uptake was irrelevant as significant toxicity was produced in these cells. H. argentea produced a concentration-dependent reduction in nitric oxide production in RAW macrophages, although not as effectively as the positive control, aminoguanidine. Again, the toxicity of D. thunbergii to this cell line precludes the relevance of nitric oxide inhibition as an antidiabetic mechanism for this plant. D. thunbergii produced a concentration-dependent increase in 3T3-L1 triglyceride accumulation, as measured by Oil red O staining, compared to untreated cells, while H. argentea exerted no significant alterations in pre- adipocyte differentiation. Generally, the two plants produced weak inhibition of the activities of the various enzymes measured, suggesting that this mechanism may not play a major role in the activities of these plants as possible antidiabetic agents. GC-MS analysis revealed major differences in the volatile oil composition between fresh and dried plant parts for both plants. Most notably, total terpenoid content of D. thunbergii oils reduced significantly from 77.17 percent in the fresh root oil to 47.58 percent in the dried root oil. Total terpenoid content was much lower in H. argentea oils, but similarly reduced from 10.58 percent in the fresh corm oil to 4.00 percent in the dried corm oil. LC-MS analysis enabled the tentative identification of compounds including phenolic glycosides, flavonoids, alkaloids, terpenoids saponins and sapogenins, many of which have been reported in literature to exert bioactivities relevant to the ones elucidated in the present study. Overall, H. argentea exhibited antidiabetic properties that may be mediated by its stimulation of glucose uptake in HepG2 and L6 cells; stimulation of proliferation in INS-1 cells; lack of stimulation of 3T3-L1 triglyceride accumulation and a tendency to reduce nitric oxide production in RAW macrophages. These activities suggest that H. argentea has promise for further investigations as an antidiabetic agent. On the contrary, D. thunbergii exhibited significant toxicity to HepG2 cells, INS-1 cells and RAW macrophages. Its cytotoxicity at the concentrations investigated in the present studies raises significant concerns about any potential antidiabetic applications for this plant.
- Full Text:
- Date Issued: 2017
- Authors: Akinrinde, Akinleye Stephen
- Date: 2017
- Subjects: Medicinal plants--South Africa--Eastern Cape Traditional medicine--South Africa--Eastern Cape Diabetics--Alternative treatment--South Africa
- Language: English
- Type: Thesis , Doctoral , Biochemistry
- Identifier: http://hdl.handle.net/10353/16036 , vital:40606
- Description: Diabetes mellitus is a chronic metabolic disorder primarily characterized by elevated blood glucose levels. Its rapidly increasing prevalence as a major non-communicable disease is now a growing concern for both developed and developing countries. The development of safe, cost-effective and pharmacologically-effective medications continues to a major challenge of antidiabetic management. Since most conventional antidiabetic drugs are costly and present with numerous adverse effects, alternatives are increasingly being sought from natural sources, most notably medicinal plants, as viable approaches to tackling the scourge of this disease. In the Eastern Cape Province of South Africa, the roots of Dianthus thunbergii and corms of Hypoxis argentea are frequently used traditionally for the treatment of diabetes mellitus, although no scientific evidence exists to validate their effectiveness for diabetes management. The studies conducted in the resent research were, therefore, aimed at investigating the antidiabetic and toxicological properties of these plants, in an attempt to providing data towards validating their use in traditional management of diabetes mellitus. Aqueous and ethanol extracts of the underground parts of D. thunbergii and H. argentea were initially subjected to analysis of their phytochemical composition, relative to standard compounds, and the nature of their in-vitro antioxidant activities using standard spectrophotometric methods. The potentials of these extracts for cytotoxicity and/or cell proliferation were evaluated using MTT assay in HepG2 cells and Crystal violet assay in INS-1 cells. These activities were further examined in INS-1 cells using live cell fluorescence imaging techniques. To evaluate the antidiabetic properties of the extracts, they were screened for their inhibitory effects on the activities of different enzymes including α-amylase, α-glucosidase, porcine pancreatic lipase, Dipeptidyl peptidase IV (DPP-IV), collagenase and the drug metabolizing enzyme, CYP3A4, while also assessing their effects on protein glycation using in- vitro visible and fluorescence spectrophotometric approaches. Cell culture procedures were carried out to evaluate the effects of the extracts on glucose utilization in HepG2 cells and L6 myotubes; nitric oxide production in RAW 264.7 macrophages; glucose metabolism in INS-1 cells, as well as triglyceride accumulation in 3T3-L1 pre-adipocytes. Furthermore, identification of compounds present in the aqueous and ethanol extracts was carried out by Liquid chromatography- Mass spectrometry (LC-MS), while volatile oils extracted from fresh and dried parts of the two plants by hydrodistillation were also analyzed by Gas chromatography-Mass spectrometry (GC-MS). The ethanol extracts of both D. thunbergii and H. argentea contained higher amounts of total phenols, flavonoids, tannins, proanthocyanidins and alkaloids, when compared with the aqueous extracts. This finding was in direct correlation with the antioxidant activities of the extracts, with the ethanol extracts of both plants demonstrating stronger scavenging activities against hydrogen peroxide, nitric oxide, ABTS and DPPH radicals, while also exhibiting higher ferric reducing antioxidant potentials, when compared with the aqueous extracts, and in some cases, the standard antioxidants, Vitamin C, butylated hydroxytoluene and rutin. The aqueous extracts of D. thunbergii exhibited the highest toxicity in HepG2 cells with IC50 < 50 μg/ml, while also producing a concentration-dependent reduction in the viability of INS-1 cells up to 41.81percent at 50 μg/ml. Both extracts of H. argentea, however, did not produce any significant toxicity in these cells. Fluorescence imaging of live INS-1 cells using Hoechst and propidium iodide staining revealed stimulation of cell proliferation by H. argentea, while the cytotoxicity of D. thunbergii was further confirmed. H. argentea caused stimulation of glucose uptake in HepG2 cells up to 119.58 percent at 100 μg/ml and as much as 116.96 percent in L6 myotubes at 50 μg/ml, without showing toxicity to these cells. D. thunbergii produced 18.39 percent increase in L6 glucose uptake above untreated control; although its effect on HepG2 glucose uptake was irrelevant as significant toxicity was produced in these cells. H. argentea produced a concentration-dependent reduction in nitric oxide production in RAW macrophages, although not as effectively as the positive control, aminoguanidine. Again, the toxicity of D. thunbergii to this cell line precludes the relevance of nitric oxide inhibition as an antidiabetic mechanism for this plant. D. thunbergii produced a concentration-dependent increase in 3T3-L1 triglyceride accumulation, as measured by Oil red O staining, compared to untreated cells, while H. argentea exerted no significant alterations in pre- adipocyte differentiation. Generally, the two plants produced weak inhibition of the activities of the various enzymes measured, suggesting that this mechanism may not play a major role in the activities of these plants as possible antidiabetic agents. GC-MS analysis revealed major differences in the volatile oil composition between fresh and dried plant parts for both plants. Most notably, total terpenoid content of D. thunbergii oils reduced significantly from 77.17 percent in the fresh root oil to 47.58 percent in the dried root oil. Total terpenoid content was much lower in H. argentea oils, but similarly reduced from 10.58 percent in the fresh corm oil to 4.00 percent in the dried corm oil. LC-MS analysis enabled the tentative identification of compounds including phenolic glycosides, flavonoids, alkaloids, terpenoids saponins and sapogenins, many of which have been reported in literature to exert bioactivities relevant to the ones elucidated in the present study. Overall, H. argentea exhibited antidiabetic properties that may be mediated by its stimulation of glucose uptake in HepG2 and L6 cells; stimulation of proliferation in INS-1 cells; lack of stimulation of 3T3-L1 triglyceride accumulation and a tendency to reduce nitric oxide production in RAW macrophages. These activities suggest that H. argentea has promise for further investigations as an antidiabetic agent. On the contrary, D. thunbergii exhibited significant toxicity to HepG2 cells, INS-1 cells and RAW macrophages. Its cytotoxicity at the concentrations investigated in the present studies raises significant concerns about any potential antidiabetic applications for this plant.
- Full Text:
- Date Issued: 2017
Antimalarial secondary metabolites from Morinda lucida
- Authors: Chithambo, Bertha
- Date: 2017
- Subjects: Botanical chemistry , Anthraquinones , Antimalarials , Rubiaceae -- Therapeutic use , Malaria -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45730 , vital:25535
- Description: Antimalarial activities of secondary metabolites from Morinda lucida (Rubiaceae), were investigated. Even though M. lucida is traditionally used to treat malaria, diabetes, jaundice, hypertension, dysentery and many other diseases, the compounds in this plant have not yet been fully investigated and characterised. Most of the studies that have been done on this plant focused on the medicinal properties of the crude extracts but have not gone further to isolate and characterise the compounds. In this study, the methanol - dichloromethane crude extract from the bark of M. lucida was fractionated into fractions 1-8. Fractions 2-5 were purified in order to isolate active secondary metabolites. The isolated pure compounds were characterised and identified. An in vitro antimalarial assay was carried out on the crude extract, fractions, pure compounds and solutions made from different combinations of pure compounds using the parasite lactate dehydrogenase (pLDH) assay. An IC50 done on the methanolic crude extract gave a value of 25 µg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Each of the pure compounds tested had very little activity. Their activities were increased when samples from the different compounds were mixed. One of these mixtures reduced malaria viability to about 22 % at 20 µM and gave an IC50 value of 17 µM. Antibacterial assays were also carried out on the crude extract and fractions. Fractions 2 and 3 were relatively active (MIC values ranging between 125-1000 µg/mL) against M. cattarhalis and E. faecalis. Fraction 2 was also the most active on S. typhimurium and S. aureus (MIC value of 1000 µg/mL) compared with the other fractions. This same fraction also showed some activity against M. tuberculosis with MIC90 and MIC99 values of 40.9 and 46.3 µg/mL respectively in an anti-tuberculosis assay.The following compounds, comprising of iridoids (asperuloside and asperulosidic acid), terpenoids (stigmasterol, P-sitosterol, campesterol, lanosterol and cycloartenol) and anthraquinones [5,15-O-dimethylmorindol, 1,7-dihydroxy-2-methoxy-5-(methoxymethyl) anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone], were isolated. All these compounds have been isolated from different plants before with the exception of 1,7-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone which were tentatively assigned the structures due to insufficient data. To the best of our knowledge, this is the first report on the identification of all of the mentioned compounds, with the exception of ß-sitosterol and stigmasterol, from M. lucida. Molecular docking was performed on one of the isolated anthraquinones (5,15-O- dimethylmorindol) to check if it can bind to cytochrome bci, a known target for atovaquone. This compound interacted with the same amino acids that atovaquone, a well known antimalarial agent, interacted with on cytochrome bc1 indicating a possible similar mode of action.
- Full Text:
- Date Issued: 2017
- Authors: Chithambo, Bertha
- Date: 2017
- Subjects: Botanical chemistry , Anthraquinones , Antimalarials , Rubiaceae -- Therapeutic use , Malaria -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/45730 , vital:25535
- Description: Antimalarial activities of secondary metabolites from Morinda lucida (Rubiaceae), were investigated. Even though M. lucida is traditionally used to treat malaria, diabetes, jaundice, hypertension, dysentery and many other diseases, the compounds in this plant have not yet been fully investigated and characterised. Most of the studies that have been done on this plant focused on the medicinal properties of the crude extracts but have not gone further to isolate and characterise the compounds. In this study, the methanol - dichloromethane crude extract from the bark of M. lucida was fractionated into fractions 1-8. Fractions 2-5 were purified in order to isolate active secondary metabolites. The isolated pure compounds were characterised and identified. An in vitro antimalarial assay was carried out on the crude extract, fractions, pure compounds and solutions made from different combinations of pure compounds using the parasite lactate dehydrogenase (pLDH) assay. An IC50 done on the methanolic crude extract gave a value of 25 µg/mL. The % cell viability for the crude extract in cell toxicity assay remained at 100%. Each of the pure compounds tested had very little activity. Their activities were increased when samples from the different compounds were mixed. One of these mixtures reduced malaria viability to about 22 % at 20 µM and gave an IC50 value of 17 µM. Antibacterial assays were also carried out on the crude extract and fractions. Fractions 2 and 3 were relatively active (MIC values ranging between 125-1000 µg/mL) against M. cattarhalis and E. faecalis. Fraction 2 was also the most active on S. typhimurium and S. aureus (MIC value of 1000 µg/mL) compared with the other fractions. This same fraction also showed some activity against M. tuberculosis with MIC90 and MIC99 values of 40.9 and 46.3 µg/mL respectively in an anti-tuberculosis assay.The following compounds, comprising of iridoids (asperuloside and asperulosidic acid), terpenoids (stigmasterol, P-sitosterol, campesterol, lanosterol and cycloartenol) and anthraquinones [5,15-O-dimethylmorindol, 1,7-dihydroxy-2-methoxy-5-(methoxymethyl) anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone], were isolated. All these compounds have been isolated from different plants before with the exception of 1,7-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone and 1,6-dihydroxy-2-methoxy-5-(methoxymethyl)anthraquinone which were tentatively assigned the structures due to insufficient data. To the best of our knowledge, this is the first report on the identification of all of the mentioned compounds, with the exception of ß-sitosterol and stigmasterol, from M. lucida. Molecular docking was performed on one of the isolated anthraquinones (5,15-O- dimethylmorindol) to check if it can bind to cytochrome bci, a known target for atovaquone. This compound interacted with the same amino acids that atovaquone, a well known antimalarial agent, interacted with on cytochrome bc1 indicating a possible similar mode of action.
- Full Text:
- Date Issued: 2017
Antimicrobial activity of selected plants and their combined preparations against pathogens causing respiratory infections
- Authors: Onyebuchi, Ukwuoma Collins
- Date: 2017
- Subjects: Anti-infective agents , Respiratory infections -- Alternative treatment
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/21197 , vital:29455
- Description: Bacterial infection of the respiratory system is one of the leading causes of death in the world’s population, killing over four million people annually. Treatment of respiratory infections is usually by antibiotics administration. The emergence of multi-drug-resistant pathogens has led to the search for more effective therapeutic agents especially from medicinal plants, as compounds from plants have been shown to possess some therapeutic potential. The aim of this study is to determine the antimicrobial activity of three plants, Tetradenia riparia, Leonotis leonurus and Salvia africana-lutea and the activity of their various combined preparations against 27 pathogens usually associated with respiratory ailments. Various solvents were used for extraction of the dried powdered plant materials. The agar disc diffusion antimicrobial assay and the micro-dilution assay methods were used to determine the inhibitory activity and the minimum inhibitory concentration of the plant extracts. The nature of phytochemicals present in the extracts was determined by thin layer chromatography. The results obtained in this study, showed that ethanol produced the highest average extract yield in both the individual and combined plant preparations. A two-way analysis of variance for the disc diffusion assay showed no significant difference in the inhibition zones (Appendix 1 and 2). MIC of 0.8 mg/ml was obtained with S. africana-lutea against S. pneumoniae ATCC 49619 and B. cereus ATCC 10976 strains, indicating a strong antibacterial activity. Synergistic interaction (FIC index ranging from 0.20 – 0.50) and a strong antimicrobial activity (MIC values ranging from 0.4 – 0.8 mg/ml), was obtained with the acetone extract of the 1:1 combination of L. leonurus with S. africana-lutea. The XEA and CEF solvent systems eluted the most number of compound spots and produced the best separations. The results obtained in this study validate the traditional use of these plants and their combinations for the treatment of respiratory ailments.
- Full Text:
- Date Issued: 2017
- Authors: Onyebuchi, Ukwuoma Collins
- Date: 2017
- Subjects: Anti-infective agents , Respiratory infections -- Alternative treatment
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/21197 , vital:29455
- Description: Bacterial infection of the respiratory system is one of the leading causes of death in the world’s population, killing over four million people annually. Treatment of respiratory infections is usually by antibiotics administration. The emergence of multi-drug-resistant pathogens has led to the search for more effective therapeutic agents especially from medicinal plants, as compounds from plants have been shown to possess some therapeutic potential. The aim of this study is to determine the antimicrobial activity of three plants, Tetradenia riparia, Leonotis leonurus and Salvia africana-lutea and the activity of their various combined preparations against 27 pathogens usually associated with respiratory ailments. Various solvents were used for extraction of the dried powdered plant materials. The agar disc diffusion antimicrobial assay and the micro-dilution assay methods were used to determine the inhibitory activity and the minimum inhibitory concentration of the plant extracts. The nature of phytochemicals present in the extracts was determined by thin layer chromatography. The results obtained in this study, showed that ethanol produced the highest average extract yield in both the individual and combined plant preparations. A two-way analysis of variance for the disc diffusion assay showed no significant difference in the inhibition zones (Appendix 1 and 2). MIC of 0.8 mg/ml was obtained with S. africana-lutea against S. pneumoniae ATCC 49619 and B. cereus ATCC 10976 strains, indicating a strong antibacterial activity. Synergistic interaction (FIC index ranging from 0.20 – 0.50) and a strong antimicrobial activity (MIC values ranging from 0.4 – 0.8 mg/ml), was obtained with the acetone extract of the 1:1 combination of L. leonurus with S. africana-lutea. The XEA and CEF solvent systems eluted the most number of compound spots and produced the best separations. The results obtained in this study validate the traditional use of these plants and their combinations for the treatment of respiratory ailments.
- Full Text:
- Date Issued: 2017
Aporias of Rock Art interpretation: advancing a phenomenological reading
- Authors: Horwitz, Nomvuyo
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145609 , vital:38451 , https://0-doi.org.wam.seals.ac.za/10.1162/AFAR_a_00342
- Description: A porias—from the Greek a + poros (“without” + “passage”)—are defined by Jacques Derrida (1993) as philosophical expressions of doubt and confusion; they are irresolvable logical disjunctions in a given line of enquiry. Stuart Murray (2009:11) describes aporias as being constituted by “an intrinsic undecidability … a contradiction, a puzzle or a paradox.” In this article, I argue that academic interpretation of San rock art has been marked by certain aporias—moments of inherent, irresolvable confusion or doubt—because of the methodological tendencies that contemporary researchers have employed. By viewing the interpretation of San paintings as a detective-like “deciphering”—that is, as a journey that must end at the “arrival” of a static meaning— researchers have created pockets of contradictions: San rock art paintings are part of a process of perceptual meaning-making through aesthetic expression, not merely clues for deciphering a simplified “bygone” past. In this view, I advance a phenomenological approach to interpreting these paintings.
- Full Text:
- Date Issued: 2017
- Authors: Horwitz, Nomvuyo
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145609 , vital:38451 , https://0-doi.org.wam.seals.ac.za/10.1162/AFAR_a_00342
- Description: A porias—from the Greek a + poros (“without” + “passage”)—are defined by Jacques Derrida (1993) as philosophical expressions of doubt and confusion; they are irresolvable logical disjunctions in a given line of enquiry. Stuart Murray (2009:11) describes aporias as being constituted by “an intrinsic undecidability … a contradiction, a puzzle or a paradox.” In this article, I argue that academic interpretation of San rock art has been marked by certain aporias—moments of inherent, irresolvable confusion or doubt—because of the methodological tendencies that contemporary researchers have employed. By viewing the interpretation of San paintings as a detective-like “deciphering”—that is, as a journey that must end at the “arrival” of a static meaning— researchers have created pockets of contradictions: San rock art paintings are part of a process of perceptual meaning-making through aesthetic expression, not merely clues for deciphering a simplified “bygone” past. In this view, I advance a phenomenological approach to interpreting these paintings.
- Full Text:
- Date Issued: 2017
Apparent digestibility coefficients of feed ingredients and essential amino acid requirements of dusky kob (Argyrosomus japonicus)
- Authors: Adesola, Abidemi Adejoke
- Date: 2017
- Subjects: Amino acids in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32140 , vital:24014
- Description: Important to the evaluation of potential feed ingredients for inclusion in fish diets should be their digestibility and amino acid requirement so that feeds can be formulated on a digestible basis rather than a gross nutrient basis. This thesis established techniques for faecal collection, the validity of digestibility markers, it determined apparent digestibility coefficients for various novel feed ingredients, and it established the optimal lysine requirement for Argyrosomus japonicus, which was used to estimate each of the essential amino acid requirements by using the ideal protein concept. There were no significant differences in dry matter apparent digestibility coefficients when faeces were collected by stripping (77.0 %), dissection (80.1 %) or settlement (83.5 %). Faecal collection by the settlement method produced the most reliable digestibility data. Apparent digestibility coefficients for dry matter, crude protein and energy calculated using acid-insoluble ash were higher (84.0 %, 93.2 % and 93.0 %, respectively) than those using chromic oxide (55.7 %, 79.1 % and 78.2 %) and titanium dioxide (58.6 %, 79.7 % and 80.5 %). The magnitude of variation in digestibility coefficients obtained using acid-insoluble ash was always lower than that obtained with the other markers. Therefore, acid-insoluble ash was preferred as a dietary marker. Using the above protocol, protein and amino acid digestibility of some animal and plant protein ingredients were evaluated in a series of experiments. The first trial compared the apparent digestibility coefficients of some animal products included as single protein source in the test diets. Apparent protein digestibility values were 84.5 %, 83.8 %, 85.8 % and 83.1 % for fishmeal-prime, fishmeal-standard, poultry meal and pork meal, respectively. Apparent digestibility coefficients for poultry meal were comparable to those of fishmeal, which indicate its potential as a substitute for fishmeal in the diets of A. japonicus. The second trial determined the apparent coefficients of plant and animal protein sources included at 30 % into a practical reference diet (70 %). Apparent protein digestibility ranged from 92.4 % in sunflower meal to 85.5 % in corn gluten meal. Soybean meal is a promising feed ingredient in A. japonicus due to the high apparent digestibility of its protein (92.0 %) and essential amino acid digestibility (mean average 91.4 %). A fundamental assumption in fish feed formulation is that the digestibility of nutrients is additive, i.e., digestibility of a nutrient in one ingredient does not interact with the digestibility of the same nutrient in another ingredient. In the third trial, additivity of feed ingredients was tested using pork meal and poultry meal. The results indicate that the apparent digestibility coefficient of animal protein ingredients could be calculated from compound diets to accurately determine protein and amino acid digestibility in A. japonicus, and possibly other carnivorous fish species. Dietary essential amino acid requirements were determined for juvenile A. japonicus in two trials. A dose-response study was conducted using crystalline lysine to determine the optimal requirement of dietary lysine for A. japonicus. Optimal dietary lysine was estimated at 31.7 g kg-¹ dry diet, corresponding to 73.5 g kg-¹ of dietary protein, based on specific growth rate and broken-line segmented regression analyses. Dietary requirements for other essential amino acids ranged from 22 g kg-¹ (histidine) to 71 g kg-¹ (leucine) crude protein. The results of the present study provided a research tool that could be used to assess and verify the conclusions of earlier dietary work on A. japonicus and in further studies to develop least cost diet formulations for this species. The study also adds to the knowledge of the nutritional requirements of A. japonicus by providing information on the digestibility of plants and animal protein ingredients. It also contributes to future dietary research for this species because this study determines, for the first time, the most suitable methods for investigating the digestibility of raw materials for A. japonicus.
- Full Text:
- Date Issued: 2017
- Authors: Adesola, Abidemi Adejoke
- Date: 2017
- Subjects: Amino acids in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32140 , vital:24014
- Description: Important to the evaluation of potential feed ingredients for inclusion in fish diets should be their digestibility and amino acid requirement so that feeds can be formulated on a digestible basis rather than a gross nutrient basis. This thesis established techniques for faecal collection, the validity of digestibility markers, it determined apparent digestibility coefficients for various novel feed ingredients, and it established the optimal lysine requirement for Argyrosomus japonicus, which was used to estimate each of the essential amino acid requirements by using the ideal protein concept. There were no significant differences in dry matter apparent digestibility coefficients when faeces were collected by stripping (77.0 %), dissection (80.1 %) or settlement (83.5 %). Faecal collection by the settlement method produced the most reliable digestibility data. Apparent digestibility coefficients for dry matter, crude protein and energy calculated using acid-insoluble ash were higher (84.0 %, 93.2 % and 93.0 %, respectively) than those using chromic oxide (55.7 %, 79.1 % and 78.2 %) and titanium dioxide (58.6 %, 79.7 % and 80.5 %). The magnitude of variation in digestibility coefficients obtained using acid-insoluble ash was always lower than that obtained with the other markers. Therefore, acid-insoluble ash was preferred as a dietary marker. Using the above protocol, protein and amino acid digestibility of some animal and plant protein ingredients were evaluated in a series of experiments. The first trial compared the apparent digestibility coefficients of some animal products included as single protein source in the test diets. Apparent protein digestibility values were 84.5 %, 83.8 %, 85.8 % and 83.1 % for fishmeal-prime, fishmeal-standard, poultry meal and pork meal, respectively. Apparent digestibility coefficients for poultry meal were comparable to those of fishmeal, which indicate its potential as a substitute for fishmeal in the diets of A. japonicus. The second trial determined the apparent coefficients of plant and animal protein sources included at 30 % into a practical reference diet (70 %). Apparent protein digestibility ranged from 92.4 % in sunflower meal to 85.5 % in corn gluten meal. Soybean meal is a promising feed ingredient in A. japonicus due to the high apparent digestibility of its protein (92.0 %) and essential amino acid digestibility (mean average 91.4 %). A fundamental assumption in fish feed formulation is that the digestibility of nutrients is additive, i.e., digestibility of a nutrient in one ingredient does not interact with the digestibility of the same nutrient in another ingredient. In the third trial, additivity of feed ingredients was tested using pork meal and poultry meal. The results indicate that the apparent digestibility coefficient of animal protein ingredients could be calculated from compound diets to accurately determine protein and amino acid digestibility in A. japonicus, and possibly other carnivorous fish species. Dietary essential amino acid requirements were determined for juvenile A. japonicus in two trials. A dose-response study was conducted using crystalline lysine to determine the optimal requirement of dietary lysine for A. japonicus. Optimal dietary lysine was estimated at 31.7 g kg-¹ dry diet, corresponding to 73.5 g kg-¹ of dietary protein, based on specific growth rate and broken-line segmented regression analyses. Dietary requirements for other essential amino acids ranged from 22 g kg-¹ (histidine) to 71 g kg-¹ (leucine) crude protein. The results of the present study provided a research tool that could be used to assess and verify the conclusions of earlier dietary work on A. japonicus and in further studies to develop least cost diet formulations for this species. The study also adds to the knowledge of the nutritional requirements of A. japonicus by providing information on the digestibility of plants and animal protein ingredients. It also contributes to future dietary research for this species because this study determines, for the first time, the most suitable methods for investigating the digestibility of raw materials for A. japonicus.
- Full Text:
- Date Issued: 2017
Applicability of putative probiotic bacteria to replace antibiotics as growth promoters in commercial and indigenous piglets
- Authors: Dlamini, Ziyanda Confidence
- Date: 2017
- Subjects: Antibiotics , Dietary supplements , Piglets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11428 , vital:39071
- Description: Antibiotic use in pig production contributes to development of antimicrobial resistance in food animals and risk of antibiotic residues in animal food products. The use of probiotics appears to be the potential alternative to antibiotics. This work is designed to validate the applicability of administered direct-fed putative probiotic strains of Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614 and Streptococcus salivarius NBCR 13956 on growth performance, hematological parameters, and antibody stimulation in weaned commercial and indigenous pigs. Forty-five weaned piglets were divided into five treatment experimental groups as follows: Diet with: antibiotic (PC), No antibiotic and no probiotic (NC), Probiotic (P1) (P2) combination of probiotics (P3). Piglets’ performance were monitored during the trial. Faecal and ileum samples were collected for microbial count analysis. Blood samples were collected from the sacrificed piglets at the end of the trial, for the hematological and biochemical analysis and probiotics ability to stimulate immunoglobulin G (IgG). Four probiotic strains were tested for cell surface hydrophobicity against xylene, chloroform and ethyl acetate. The strains were also tested for auto-aggregation and co-aggregation abilities. Enterococcus faecalis ATCC 29212 was used as a control pathogen in the co-aggregation ability test. The probiotic strains were also screened for presence of virulence and resistance genes. DNA was extracted from all the four probiotic strains using ZR Fungal/Bacterial DNA MiniPepTM (Zymo Research, USA) following manufacturer’s instructions. The DNA samples were later amplified in PCR reactions with specific primers to detect virulence genes of adhesion collagen protein (ace), aggregation substances (agg and asa); antibiotic resistance genes of: Vancomycin vanA, Vancomycin vanC1 and Vancomycin vanC2/3. The data was analyzed by one-way ANOVA using SAS statistics software (SAS 9.3) (2003). Results from the study revealed that supplementation of probiotics had no effect on feed intake (FI) in all of the experimental groups. However, supplementation of probiotics in P3 treatment resulted in greater average daily gain (ADG) and improved feed conversion ratio (FCR) of weaned piglets (p < 0.05). Microbial count of fecal samples from all the treatment groups did not differ while ileum samples had lower enteric bacteria in P3 group as compared to other treatments. Concentration of albumin, globulin, neutrophils and basophils were high in NC treatment compared to other treatments. (p < 0.05). IgG concentration was highest in P3 compared to other treatment (p < 0.05). All probiotics strains showed high hydrophobicity to all solvents used in the test. Cell Surface Hydrophobic was highest in xylene (78percent – 84percent), followed by chloroform (68percent – 75percent) and lowest in ethyl acetate (52percent - 60percent). All of the test strains showed high auto-aggregation ability after 4 hr of incubation. L .reuteri VB4 exhibited highest auto-aggregation ability of 70percent, while the least auto-aggregation ability of 60percent was observed for L. salivarius ZJ614. In the co-aggregation assays, all probiotic bacterial strains exhibited a strong co-aggregation of 45percent to 56percent after 4 hr of incubation at 37 °C. L. reuteri VB4 exhibited highest co-aggregation ability while L. salivarius ZJ614 exhibited the lowest co-aggregation ability. No presence of virulence genes ace and asa was detected in all of the putative probiotic strains, but agg virulence gene was detected in L. reuteri VB4 strains. L. reuteri VB4 and S. salivarius NBRC13956 had resistance genes vanC 2/3 and vanC1, respectively. Overall, the results from this study, suggest that the candidate probiotics strains have enhanced the growth and measured blood parameters of the weaned piglets used in these experiments, and also, the probiotic strains have the abilities to initiate the stimulation of IgG. Probiotics could be used as a novel alternative to antibiotics in the animal nutrition and production, with the abilities to confer health benefits and promote growth. The outcome of the research advocates that these probiotics will be beneficial to pig production, and might outcompete the current antibiotics in use as growth promoters. One of the major advantages of probiotics to pig industry is the production of antibiotic free and good quality pork meat to local and international consumers, thus, enhancing South African Pork industry.
- Full Text:
- Date Issued: 2017
- Authors: Dlamini, Ziyanda Confidence
- Date: 2017
- Subjects: Antibiotics , Dietary supplements , Piglets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11428 , vital:39071
- Description: Antibiotic use in pig production contributes to development of antimicrobial resistance in food animals and risk of antibiotic residues in animal food products. The use of probiotics appears to be the potential alternative to antibiotics. This work is designed to validate the applicability of administered direct-fed putative probiotic strains of Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614 and Streptococcus salivarius NBCR 13956 on growth performance, hematological parameters, and antibody stimulation in weaned commercial and indigenous pigs. Forty-five weaned piglets were divided into five treatment experimental groups as follows: Diet with: antibiotic (PC), No antibiotic and no probiotic (NC), Probiotic (P1) (P2) combination of probiotics (P3). Piglets’ performance were monitored during the trial. Faecal and ileum samples were collected for microbial count analysis. Blood samples were collected from the sacrificed piglets at the end of the trial, for the hematological and biochemical analysis and probiotics ability to stimulate immunoglobulin G (IgG). Four probiotic strains were tested for cell surface hydrophobicity against xylene, chloroform and ethyl acetate. The strains were also tested for auto-aggregation and co-aggregation abilities. Enterococcus faecalis ATCC 29212 was used as a control pathogen in the co-aggregation ability test. The probiotic strains were also screened for presence of virulence and resistance genes. DNA was extracted from all the four probiotic strains using ZR Fungal/Bacterial DNA MiniPepTM (Zymo Research, USA) following manufacturer’s instructions. The DNA samples were later amplified in PCR reactions with specific primers to detect virulence genes of adhesion collagen protein (ace), aggregation substances (agg and asa); antibiotic resistance genes of: Vancomycin vanA, Vancomycin vanC1 and Vancomycin vanC2/3. The data was analyzed by one-way ANOVA using SAS statistics software (SAS 9.3) (2003). Results from the study revealed that supplementation of probiotics had no effect on feed intake (FI) in all of the experimental groups. However, supplementation of probiotics in P3 treatment resulted in greater average daily gain (ADG) and improved feed conversion ratio (FCR) of weaned piglets (p < 0.05). Microbial count of fecal samples from all the treatment groups did not differ while ileum samples had lower enteric bacteria in P3 group as compared to other treatments. Concentration of albumin, globulin, neutrophils and basophils were high in NC treatment compared to other treatments. (p < 0.05). IgG concentration was highest in P3 compared to other treatment (p < 0.05). All probiotics strains showed high hydrophobicity to all solvents used in the test. Cell Surface Hydrophobic was highest in xylene (78percent – 84percent), followed by chloroform (68percent – 75percent) and lowest in ethyl acetate (52percent - 60percent). All of the test strains showed high auto-aggregation ability after 4 hr of incubation. L .reuteri VB4 exhibited highest auto-aggregation ability of 70percent, while the least auto-aggregation ability of 60percent was observed for L. salivarius ZJ614. In the co-aggregation assays, all probiotic bacterial strains exhibited a strong co-aggregation of 45percent to 56percent after 4 hr of incubation at 37 °C. L. reuteri VB4 exhibited highest co-aggregation ability while L. salivarius ZJ614 exhibited the lowest co-aggregation ability. No presence of virulence genes ace and asa was detected in all of the putative probiotic strains, but agg virulence gene was detected in L. reuteri VB4 strains. L. reuteri VB4 and S. salivarius NBRC13956 had resistance genes vanC 2/3 and vanC1, respectively. Overall, the results from this study, suggest that the candidate probiotics strains have enhanced the growth and measured blood parameters of the weaned piglets used in these experiments, and also, the probiotic strains have the abilities to initiate the stimulation of IgG. Probiotics could be used as a novel alternative to antibiotics in the animal nutrition and production, with the abilities to confer health benefits and promote growth. The outcome of the research advocates that these probiotics will be beneficial to pig production, and might outcompete the current antibiotics in use as growth promoters. One of the major advantages of probiotics to pig industry is the production of antibiotic free and good quality pork meat to local and international consumers, thus, enhancing South African Pork industry.
- Full Text:
- Date Issued: 2017
Application of graphene quantum dots functionalized with thymine and thymine-appended zinc phthalocyanine as novel photoluminescent nanoprobes
- Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188508 , vital:44760 , xlink:href="https://doi.org/10.1039/C6NJ03285K"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanine (ZnPc) were separately modified with thymine to obtain thymine-functionalized GQDs (T-GQDs) and ZnPc (T-ZnPc). T-GQDs and nanoconjugates of T-ZnPc with pristine GQDs (represented as pristine GQDs–T-ZnPc) or T-GQDs (represented as T-GQDs–T-ZnPc) were employed as fluorescent probes for the detection of mercury(II) ions (Hg2+). The as-synthesized T-GQDs alone demonstrated a highly sensitive and selective fluorescence “turn-OFF” process for Hg2+ detection due to the specific interaction between the thymine functionality on the T-GQDs with Hg2+. On the other hand, the fluorescence of pristine GQDs and T-GQDs was quenched (“turn-OFF”) upon coordination with T-ZnPc. However, the fluorescence emission was selectively restored (“turn-ON” process) in the presence of Hg2+ resulting in the sensitive detection of Hg2+ in the nanomolar concentration range (limit of detection = 0.05 nM, for the pristine GQDs–T-ZnPc probe). The probe containing pristine GQDs and the T-ZnPc complex demonstrated a higher specific and sensitive recognition of Hg2+ as compared to the T-GQDs alone or T-GQDs–T-ZnPc probes which are ascribed to the fluorescence “turn-ON” process of the former. Screening of different metal ions and counter ions proved that the probes are specifically suited for Hg2+ detection.
- Full Text:
- Date Issued: 2017
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188508 , vital:44760 , xlink:href="https://doi.org/10.1039/C6NJ03285K"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanine (ZnPc) were separately modified with thymine to obtain thymine-functionalized GQDs (T-GQDs) and ZnPc (T-ZnPc). T-GQDs and nanoconjugates of T-ZnPc with pristine GQDs (represented as pristine GQDs–T-ZnPc) or T-GQDs (represented as T-GQDs–T-ZnPc) were employed as fluorescent probes for the detection of mercury(II) ions (Hg2+). The as-synthesized T-GQDs alone demonstrated a highly sensitive and selective fluorescence “turn-OFF” process for Hg2+ detection due to the specific interaction between the thymine functionality on the T-GQDs with Hg2+. On the other hand, the fluorescence of pristine GQDs and T-GQDs was quenched (“turn-OFF”) upon coordination with T-ZnPc. However, the fluorescence emission was selectively restored (“turn-ON” process) in the presence of Hg2+ resulting in the sensitive detection of Hg2+ in the nanomolar concentration range (limit of detection = 0.05 nM, for the pristine GQDs–T-ZnPc probe). The probe containing pristine GQDs and the T-ZnPc complex demonstrated a higher specific and sensitive recognition of Hg2+ as compared to the T-GQDs alone or T-GQDs–T-ZnPc probes which are ascribed to the fluorescence “turn-ON” process of the former. Screening of different metal ions and counter ions proved that the probes are specifically suited for Hg2+ detection.
- Full Text:
- Date Issued: 2017
Application of the Morita-Baylis-Hillman reaction in the synthesis of 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones as potential HIV-1 integrase inhibitors
- Sekgota, Khethobole C, Majumder, Swarup, Isaacs, Michelle, Mnkandhla, Dumisani, Hoppe, Heinrich C, Khanye, Setshaba D, Kriel, Frederik H, Coates, Judy, Kaye, Perry T
- Authors: Sekgota, Khethobole C , Majumder, Swarup , Isaacs, Michelle , Mnkandhla, Dumisani , Hoppe, Heinrich C , Khanye, Setshaba D , Kriel, Frederik H , Coates, Judy , Kaye, Perry T
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66178 , vital:28913 , https://doi.org/10.1016/j.bioorg.2017.09.015
- Description: publisher version , A practicable six-step synthetic pathway has been developed to access a library of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones using Morita-Baylis-Hillman methodology. These compounds and their 3-[(N-cycloalkylamino)methyl]-2-quinolone precursors have been screened as potential HIV-1 integrase (IN) inhibitors. A concomitant survey of their activity against HIV-1 protease and reverse-transcriptase reveals selective inhibition of HIV-1 IN.
- Full Text: false
- Date Issued: 2017
- Authors: Sekgota, Khethobole C , Majumder, Swarup , Isaacs, Michelle , Mnkandhla, Dumisani , Hoppe, Heinrich C , Khanye, Setshaba D , Kriel, Frederik H , Coates, Judy , Kaye, Perry T
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66178 , vital:28913 , https://doi.org/10.1016/j.bioorg.2017.09.015
- Description: publisher version , A practicable six-step synthetic pathway has been developed to access a library of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones using Morita-Baylis-Hillman methodology. These compounds and their 3-[(N-cycloalkylamino)methyl]-2-quinolone precursors have been screened as potential HIV-1 integrase (IN) inhibitors. A concomitant survey of their activity against HIV-1 protease and reverse-transcriptase reveals selective inhibition of HIV-1 IN.
- Full Text: false
- Date Issued: 2017