An evaluation of the Xenopus laevis liver slice model to study the toxic effects of microcystin
- Authors: Coates, Nadya
- Date: 2003
- Subjects: Zenopus laevis , Microcystis aeruginosa -- Toxicology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11069 , http://hdl.handle.net/10948/307 , Zenopus laevis , Microcystis aeruginosa -- Toxicology
- Description: Blooms of cyanobacteria have increased in occurrence in the past three decades and have been reported to cause severe problems for animals and humans, leading to death in extreme instances. The majority of poisonings that have taken place have been attributed to a hepatotoxin produced by the species Microcystis aeruginosa, namely microcystin. The appearance of a cyanobacterial bloom does not give any indication as to its toxicity and therefore, it is imperative that simple, yet sensitive, bioassays are developed to overcome this problem. This study was undertaken to evaluate the effects of microcystin-LR on the liver of Xenopus laevis both in vitro and in vivo. This animal provides an opportunity to study the long-term hepatotoxic effects of the toxin compared to in vitro studies performed with mice and rats. The use of the liver slice model system as a potential bioassay to study the effects of microcystin-LR on Xenopus laevis liver was evaluated. Liver slices were cultured in RPMI- 1640 culture medium for periods ranging from 30 hours to 10 days and the liver slices were exposed to toxin concentrations ranging from 1nM to 500nM. The use of frog liver slices to study the longer-term effects of low-dose exposure to microcystin-LR was evaluated by observing the ultrastructural changes within hepatocytes using transmission electron microscopy, the release of the enzymes alanine aminotransferase and lactate dehydrogenase into the surrounding culture medium, as well as using a 3-[4,5-dimethylthiazol-2yl]-2,5- diphenyl tetrazolium bromide assay to determine the viability of the liver slices in culture. The amount of lipid peroxidation in the liver slices after exposure to microcystin-LR was assessed using the Thiobarbituric Acid Test. Results showed the frog liver slice culture system to be an inadequate method to evaluate the hepatotoxic effects of microcystin-LR. An in vivo assessment of the effects of microcystin-LR on Xenopus laevis was carried out using a total of 9 frogs (3 groups of 3 frogs). Frogs received a single intraperitoneal dose of 120mg/kg of microcystin-LR and were sacrificed at 8 and 24 hours post exposure. Microcystin-LR caused no significant change in serum lactate dehydrogenase levels, hepatosomatic index (liver weight as a percentage body weight), glutathione peroxidase activity, glycogen or lipid peroxidation. There was, however, an increase in glutathione sii transferase activity in the liver. The presence of the toxin in the liver was confirmed by immunohistochemistry. This study suggests that Xenopus laevis has, in some way, adapted to detoxifying aquatic toxins in the environment.
- Full Text:
- Date Issued: 2003
- Authors: Coates, Nadya
- Date: 2003
- Subjects: Zenopus laevis , Microcystis aeruginosa -- Toxicology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11069 , http://hdl.handle.net/10948/307 , Zenopus laevis , Microcystis aeruginosa -- Toxicology
- Description: Blooms of cyanobacteria have increased in occurrence in the past three decades and have been reported to cause severe problems for animals and humans, leading to death in extreme instances. The majority of poisonings that have taken place have been attributed to a hepatotoxin produced by the species Microcystis aeruginosa, namely microcystin. The appearance of a cyanobacterial bloom does not give any indication as to its toxicity and therefore, it is imperative that simple, yet sensitive, bioassays are developed to overcome this problem. This study was undertaken to evaluate the effects of microcystin-LR on the liver of Xenopus laevis both in vitro and in vivo. This animal provides an opportunity to study the long-term hepatotoxic effects of the toxin compared to in vitro studies performed with mice and rats. The use of the liver slice model system as a potential bioassay to study the effects of microcystin-LR on Xenopus laevis liver was evaluated. Liver slices were cultured in RPMI- 1640 culture medium for periods ranging from 30 hours to 10 days and the liver slices were exposed to toxin concentrations ranging from 1nM to 500nM. The use of frog liver slices to study the longer-term effects of low-dose exposure to microcystin-LR was evaluated by observing the ultrastructural changes within hepatocytes using transmission electron microscopy, the release of the enzymes alanine aminotransferase and lactate dehydrogenase into the surrounding culture medium, as well as using a 3-[4,5-dimethylthiazol-2yl]-2,5- diphenyl tetrazolium bromide assay to determine the viability of the liver slices in culture. The amount of lipid peroxidation in the liver slices after exposure to microcystin-LR was assessed using the Thiobarbituric Acid Test. Results showed the frog liver slice culture system to be an inadequate method to evaluate the hepatotoxic effects of microcystin-LR. An in vivo assessment of the effects of microcystin-LR on Xenopus laevis was carried out using a total of 9 frogs (3 groups of 3 frogs). Frogs received a single intraperitoneal dose of 120mg/kg of microcystin-LR and were sacrificed at 8 and 24 hours post exposure. Microcystin-LR caused no significant change in serum lactate dehydrogenase levels, hepatosomatic index (liver weight as a percentage body weight), glutathione peroxidase activity, glycogen or lipid peroxidation. There was, however, an increase in glutathione sii transferase activity in the liver. The presence of the toxin in the liver was confirmed by immunohistochemistry. This study suggests that Xenopus laevis has, in some way, adapted to detoxifying aquatic toxins in the environment.
- Full Text:
- Date Issued: 2003
An exploration into the reasons for the resignation of ex-employees from the University of Port Elizabeth against international indicators in employee retention
- Authors: Anderson, Amber Cristal
- Date: 2003
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:11000 , http://hdl.handle.net/10948/289
- Description: South African organisations have not been left untouched by the impact of globalisation on their business practices. In a bid to maintain and improve on their competitive advantage, they have had to embark on initiatives to secure a place in the global economy. Entwined herein is the challenge to embrace a whole new definition of equality and develop their human capital as described in various legislative interventions of the South African Government. This study reflects the outcomes of an exploratory study into the reasons for the resignation of ex-employees from the University of Port Elizabeth, against international indicators in employee retention. The research was based on the premise that an effective and efficient transformation strategy should originate from a tangible understanding of all the socio-behavioural and influencing aspects of employee retention. The results suggest the development of an employee-retention strategy which could facilitate the realisation of the Employment Equity Plan. The objectives of the study were: to provide critical insight into why employees are resigning from the University of Port Elizabeth (UPE), to determine the social and developmental expectations of ex-UPE employees while in a transforming organisation, to identify and analyse ex-employees’ perceptions of the implementation of UPE’s Employment Equity Plan, to analyse ex-employees’ perceptions of existing retention practices at UPE, to provide recommendations towards an employee-retention strategy for UPE. The study is exploratory and descriptive in nature, and is quantitatively analysed with limited qualitative inferences. The population consisted of ex-UPE employees who had left the service of the university, from 01 January 2000 to 31 October 2002, by resignation. The period coincided with the implementation phase of the UPE Employment Equity Plan. For the purpose of this study, N=69. Twenty-eight ex-employees were untraceable, therefore n=41. Thirty ex-employees took part in the survey, thus making the sample return 73%. Eight of the respondents were dispersed across three continents other than Africa. The survey instrument, administered as an e-mailed and mailed questionnaire, was selected as the most suitable quantitative research method, because respondents were globally dispersed. Content analysis was selected as the most appropriate technique to produce findings in the qualitative aspect of the research. Where appropriate, descriptive statistics (univariate and bivariate analyses) were applied to describe the variables, the results of which were exhibited as tabular or graphical displays. Inferential statistical analyses (Pearson Chi-square and M-L Chisquare tests) were also conducted.
- Full Text:
- Date Issued: 2003
- Authors: Anderson, Amber Cristal
- Date: 2003
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:11000 , http://hdl.handle.net/10948/289
- Description: South African organisations have not been left untouched by the impact of globalisation on their business practices. In a bid to maintain and improve on their competitive advantage, they have had to embark on initiatives to secure a place in the global economy. Entwined herein is the challenge to embrace a whole new definition of equality and develop their human capital as described in various legislative interventions of the South African Government. This study reflects the outcomes of an exploratory study into the reasons for the resignation of ex-employees from the University of Port Elizabeth, against international indicators in employee retention. The research was based on the premise that an effective and efficient transformation strategy should originate from a tangible understanding of all the socio-behavioural and influencing aspects of employee retention. The results suggest the development of an employee-retention strategy which could facilitate the realisation of the Employment Equity Plan. The objectives of the study were: to provide critical insight into why employees are resigning from the University of Port Elizabeth (UPE), to determine the social and developmental expectations of ex-UPE employees while in a transforming organisation, to identify and analyse ex-employees’ perceptions of the implementation of UPE’s Employment Equity Plan, to analyse ex-employees’ perceptions of existing retention practices at UPE, to provide recommendations towards an employee-retention strategy for UPE. The study is exploratory and descriptive in nature, and is quantitatively analysed with limited qualitative inferences. The population consisted of ex-UPE employees who had left the service of the university, from 01 January 2000 to 31 October 2002, by resignation. The period coincided with the implementation phase of the UPE Employment Equity Plan. For the purpose of this study, N=69. Twenty-eight ex-employees were untraceable, therefore n=41. Thirty ex-employees took part in the survey, thus making the sample return 73%. Eight of the respondents were dispersed across three continents other than Africa. The survey instrument, administered as an e-mailed and mailed questionnaire, was selected as the most suitable quantitative research method, because respondents were globally dispersed. Content analysis was selected as the most appropriate technique to produce findings in the qualitative aspect of the research. Where appropriate, descriptive statistics (univariate and bivariate analyses) were applied to describe the variables, the results of which were exhibited as tabular or graphical displays. Inferential statistical analyses (Pearson Chi-square and M-L Chisquare tests) were also conducted.
- Full Text:
- Date Issued: 2003
An exploration of adolescent risk-taking behaviour : a case study analysis
- Authors: Dietrich, Valerie
- Date: 2003
- Subjects: Teenagers -- South Africa -- Conduct of life , Risk-taking (psychology) in adolescence
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10989 , http://hdl.handle.net/10948/312 , Teenagers -- South Africa -- Conduct of life , Risk-taking (psychology) in adolescence
- Description: Do adolescents of colour really engage in risk-taking behaviours as often generalised by the public? Are they in fact the alcohol, drugs, sex, and violence generation? This study attempts to investigate the conditions influencing the choices adolescents make prior to their engaging in risk-taking behaviours. In the social sciences, concerns over adolescents’ recklessly irresponsible behaviours have deep roots. In 1904 G. Stanley Hall depicted adolescence as misbehaving because of the storms and stresses of the transition from childhood to adulthood. Subsequently, social scientists produced substantial evidence that the storminess of adolescence is largely an over generalisation, which has not been empirically substantiated. In corroboration of this interpretation, this study also indicates that not all adolescents engage in risk-taking behaviour, and those risky individuals do not necessarily engage in all spheres of risk-taking. The majority of the target group only experimented with certain risk behaviours by engaging in them on one occasion only. The specific high school was selected because the researcher knew the learners, as she was an educator there at the time. She was thus reasonably aware of the frequency, the nature and the severity of the risk-taking behaviours of the target group. In general, the most important findings of the study signified a moderate level of participation in risk-taking activities. However, in certain spheres such as cigarette smoking, alcohol usage and sexual intercourse, an extreme participation level was reported. Certain factors such as gender, age, socio-economic conditions, parental (one or both) absence, and the respondents’ attitude towards the specific behaviour, were discovered to have played an influential role in the target group taking risks. Based on the reasons advanced for engaging in risk-taking behaviour, the researcher concluded that the following theories were applicable in explaining the behaviour of the respondents. These theories are the social learning theory, symbolic interactionist theory, social identity, the theory of reasoned action, and Maslow’s hierarchy of needs. The researcher trusts that this study will assist the reader to understand the complex contributing circumstances that the target group has to contend with in making decisions.
- Full Text:
- Date Issued: 2003
- Authors: Dietrich, Valerie
- Date: 2003
- Subjects: Teenagers -- South Africa -- Conduct of life , Risk-taking (psychology) in adolescence
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10989 , http://hdl.handle.net/10948/312 , Teenagers -- South Africa -- Conduct of life , Risk-taking (psychology) in adolescence
- Description: Do adolescents of colour really engage in risk-taking behaviours as often generalised by the public? Are they in fact the alcohol, drugs, sex, and violence generation? This study attempts to investigate the conditions influencing the choices adolescents make prior to their engaging in risk-taking behaviours. In the social sciences, concerns over adolescents’ recklessly irresponsible behaviours have deep roots. In 1904 G. Stanley Hall depicted adolescence as misbehaving because of the storms and stresses of the transition from childhood to adulthood. Subsequently, social scientists produced substantial evidence that the storminess of adolescence is largely an over generalisation, which has not been empirically substantiated. In corroboration of this interpretation, this study also indicates that not all adolescents engage in risk-taking behaviour, and those risky individuals do not necessarily engage in all spheres of risk-taking. The majority of the target group only experimented with certain risk behaviours by engaging in them on one occasion only. The specific high school was selected because the researcher knew the learners, as she was an educator there at the time. She was thus reasonably aware of the frequency, the nature and the severity of the risk-taking behaviours of the target group. In general, the most important findings of the study signified a moderate level of participation in risk-taking activities. However, in certain spheres such as cigarette smoking, alcohol usage and sexual intercourse, an extreme participation level was reported. Certain factors such as gender, age, socio-economic conditions, parental (one or both) absence, and the respondents’ attitude towards the specific behaviour, were discovered to have played an influential role in the target group taking risks. Based on the reasons advanced for engaging in risk-taking behaviour, the researcher concluded that the following theories were applicable in explaining the behaviour of the respondents. These theories are the social learning theory, symbolic interactionist theory, social identity, the theory of reasoned action, and Maslow’s hierarchy of needs. The researcher trusts that this study will assist the reader to understand the complex contributing circumstances that the target group has to contend with in making decisions.
- Full Text:
- Date Issued: 2003
An exploration of market growth and development stategies for franchising a selected fast food outlet
- Authors: Snyman, Dion Cedric
- Date: 2003
- Subjects: Market share , Food industry and trade -- South Africa -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10896 , http://hdl.handle.net/10948/128 , Market share , Food industry and trade -- South Africa -- Management
- Description: The advent of globalisation and the re-admittance of South Africa into the international market place have presented both opportunities and threats to local fast food outlets and franchises. These food outlets are faced with foreign competition and the need to adapt their strategies in order to cope with the continued onslaught of these highly efficient, foreign, service orientated organisations if they intend to survive. This research explored the strategies these fast food outlets should utilise to deal with their competition and to facilitate their market growth and organisational development which could lead to them being successfully franchised at a later stage. The study revealed that if any significant growth and organisational development was to be expected, the fast food outlet had to concentrate on customer satisfaction and retention through the innovative use of the 7P’s of the marketing mix in its strategy formulation process. Attention also needed to be given to the competitive forces in the external environment so that competitive strategies were in line with market developments. The triangulation method was applied in this study. In terms of this method, qualitative and quantitative research techniques are combined in order to improve the reliability and validity of the research findings. This method proved to be an effective research tool as the findings in the quantitative research were verified by the findings in the qualitative research. Franchising in South Africa, especially the Eastern Cape, where unemployment is highest, is important as it has the potential for job creation and economic empowerment of the disadvantaged communities. It is therefore essential that every endeavour be made to ensure the success of the emerging entrepreneurs through assisting them to develop strategies that will ensure sustainable development and growth.
- Full Text:
- Date Issued: 2003
- Authors: Snyman, Dion Cedric
- Date: 2003
- Subjects: Market share , Food industry and trade -- South Africa -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10896 , http://hdl.handle.net/10948/128 , Market share , Food industry and trade -- South Africa -- Management
- Description: The advent of globalisation and the re-admittance of South Africa into the international market place have presented both opportunities and threats to local fast food outlets and franchises. These food outlets are faced with foreign competition and the need to adapt their strategies in order to cope with the continued onslaught of these highly efficient, foreign, service orientated organisations if they intend to survive. This research explored the strategies these fast food outlets should utilise to deal with their competition and to facilitate their market growth and organisational development which could lead to them being successfully franchised at a later stage. The study revealed that if any significant growth and organisational development was to be expected, the fast food outlet had to concentrate on customer satisfaction and retention through the innovative use of the 7P’s of the marketing mix in its strategy formulation process. Attention also needed to be given to the competitive forces in the external environment so that competitive strategies were in line with market developments. The triangulation method was applied in this study. In terms of this method, qualitative and quantitative research techniques are combined in order to improve the reliability and validity of the research findings. This method proved to be an effective research tool as the findings in the quantitative research were verified by the findings in the qualitative research. Franchising in South Africa, especially the Eastern Cape, where unemployment is highest, is important as it has the potential for job creation and economic empowerment of the disadvantaged communities. It is therefore essential that every endeavour be made to ensure the success of the emerging entrepreneurs through assisting them to develop strategies that will ensure sustainable development and growth.
- Full Text:
- Date Issued: 2003
An integrated economic developmental appraisal of the South African mariculture industry
- Authors: Hepburn, Bruce
- Date: 2003
- Subjects: Mariculture -- South Africa -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:941 , http://hdl.handle.net/10962/d1002674 , Mariculture -- South Africa -- Economic aspects
- Description: Current coastal legislative and institutional reformulation has effectively established new principles for the promotion of sustainable, co-ordinated integrated coastal development to be achieved through facilitatory, co-operative management mechanisms. In accordance, collaborative expansion and diversification of mariculture has been identified as a strategic mechanism for realising sustainable coastal development. Present limited foundational understanding regarding the emergent commercial contingent’s economic-institutional structure has constrained the effectiveness of current centralised broad objective formulation based planning techniques. By drawing upon findings of the 2001 National Mariculture Baseline survey, key economic development and institutional components requiring dedicated attention for further realising industry’s inherent growth potential to supply domestic and growing global aquaculture markets are examined in an inductive explorative framework. Attention is also directed towards promoting realisation of collaborative mariculture development initiatives to redress dualistic development disparities in previously marginalised coastal localities. Finally, synthesis between traditional bureaucratic centralised co-ordinated planning and regionalised decentralised implementation orientated capacity building frameworks displaying a greater relevant stakeholder participatory ethos are examined.
- Full Text:
- Date Issued: 2003
- Authors: Hepburn, Bruce
- Date: 2003
- Subjects: Mariculture -- South Africa -- Economic aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:941 , http://hdl.handle.net/10962/d1002674 , Mariculture -- South Africa -- Economic aspects
- Description: Current coastal legislative and institutional reformulation has effectively established new principles for the promotion of sustainable, co-ordinated integrated coastal development to be achieved through facilitatory, co-operative management mechanisms. In accordance, collaborative expansion and diversification of mariculture has been identified as a strategic mechanism for realising sustainable coastal development. Present limited foundational understanding regarding the emergent commercial contingent’s economic-institutional structure has constrained the effectiveness of current centralised broad objective formulation based planning techniques. By drawing upon findings of the 2001 National Mariculture Baseline survey, key economic development and institutional components requiring dedicated attention for further realising industry’s inherent growth potential to supply domestic and growing global aquaculture markets are examined in an inductive explorative framework. Attention is also directed towards promoting realisation of collaborative mariculture development initiatives to redress dualistic development disparities in previously marginalised coastal localities. Finally, synthesis between traditional bureaucratic centralised co-ordinated planning and regionalised decentralised implementation orientated capacity building frameworks displaying a greater relevant stakeholder participatory ethos are examined.
- Full Text:
- Date Issued: 2003
An investigation into relationship-marketing strategies used by Morkels to retain customers
- Authors: Giddy, Peter Allan Spence
- Date: 2003
- Subjects: Relationship marketing -- South Africa , Morkels (Firm, South Africa) , Furniture industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10855 , http://hdl.handle.net/10948/134 , Relationship marketing -- South Africa , Morkels (Firm, South Africa) , Furniture industry and trade -- South Africa
- Description: The research problem addressed in this study was an assessment of the relationship-marketing strategy that Morkels currently has in operation. This strategy focuses on membership of a club that is sold to customers when they open an account. The strategy is to keep in touch with the customer by means of the club magazine, a club card and various special events and offers that are exclusive to club members. The strategy, however, may not be entirely successful in achieving the goals and objectives as envisaged by the senior management of the company. The objective of the research was to establish what exactly relationship marketing is. Once having investigated the theory of relationship marketing, the objective of the research was to establish what the goals of the management at Morkels were and whether or not these goals were met. The methodology of the research was, firstly, to conduct a literature survey on relationship marketing. In particular the study of literature focused on the theory related to the retail market focussing essentially where similar marketing strategies had been investigated. A variety of aspects of relationship marketing and strategies that had previously been implemented were then examined. The literature survey also considered the way in which a successful strategy of relationship-marketing should be motivated, planned, implemented and followed through. Secondly the research established what the goals and objectives of the management of Morkels were by means of an investigation into the policies and manuals of the relationship-marketing department. Finally a questionnaire was disseminated to the senior management of Morkels to establish what they considered to be the needs and opinions of the customers of the Garden Route Area. A second questionnaire with similar questions was also submitted to a sample of club members. This was done to establish the opinions of both groups. The major findings of the research were that Morkels is experiencing a degree of success with its relationship-marketing strategy. The research findings also revealed that opinions of the customers and the management of Morkels do not concur on a number of issues. These differences and the most important factors were discussed and recommendations were made to management.
- Full Text:
- Date Issued: 2003
- Authors: Giddy, Peter Allan Spence
- Date: 2003
- Subjects: Relationship marketing -- South Africa , Morkels (Firm, South Africa) , Furniture industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10855 , http://hdl.handle.net/10948/134 , Relationship marketing -- South Africa , Morkels (Firm, South Africa) , Furniture industry and trade -- South Africa
- Description: The research problem addressed in this study was an assessment of the relationship-marketing strategy that Morkels currently has in operation. This strategy focuses on membership of a club that is sold to customers when they open an account. The strategy is to keep in touch with the customer by means of the club magazine, a club card and various special events and offers that are exclusive to club members. The strategy, however, may not be entirely successful in achieving the goals and objectives as envisaged by the senior management of the company. The objective of the research was to establish what exactly relationship marketing is. Once having investigated the theory of relationship marketing, the objective of the research was to establish what the goals of the management at Morkels were and whether or not these goals were met. The methodology of the research was, firstly, to conduct a literature survey on relationship marketing. In particular the study of literature focused on the theory related to the retail market focussing essentially where similar marketing strategies had been investigated. A variety of aspects of relationship marketing and strategies that had previously been implemented were then examined. The literature survey also considered the way in which a successful strategy of relationship-marketing should be motivated, planned, implemented and followed through. Secondly the research established what the goals and objectives of the management of Morkels were by means of an investigation into the policies and manuals of the relationship-marketing department. Finally a questionnaire was disseminated to the senior management of Morkels to establish what they considered to be the needs and opinions of the customers of the Garden Route Area. A second questionnaire with similar questions was also submitted to a sample of club members. This was done to establish the opinions of both groups. The major findings of the research were that Morkels is experiencing a degree of success with its relationship-marketing strategy. The research findings also revealed that opinions of the customers and the management of Morkels do not concur on a number of issues. These differences and the most important factors were discussed and recommendations were made to management.
- Full Text:
- Date Issued: 2003
An investigation into strategies which enable South African women to break through the glass ceiling
- Authors: Peens, Maritha
- Date: 2003
- Subjects: Women executives -- South Africa , Women employees -- Promotions -- South Africa , Sex discrimination in employement -- South Africa , Sex discrimination against women -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10898 , http://hdl.handle.net/10948/135 , Women executives -- South Africa , Women employees -- Promotions -- South Africa , Sex discrimination in employement -- South Africa , Sex discrimination against women -- South Africa
- Description: The objective of this study was to identify the strategies (personal and organisational) that would enable South African women to break through the glass ceiling. A questionaire was designed based on the strategies found in a literature study on the topic and used to gather inputs from executive women in South Africa. A combination of snowball and self-selection sampling was used. The questionaire was sent to 138 potential respondents, mostly by means of electronic mail. Of the 47 completed questionairs returned, 44 could be used. These were processed and anaylsed using Microsoft Excel spreadsheets and the STATISTICA Version 6 software. In generaL, support was found for personal strategies pertaining to career management, networking (especially the relationship building activities), the reconciliation of home and work responsibilities with the emphasis on building a support system, education, business and organisational insught, skills development and increased input, but not for the assimilation of masculine attributes. Networking opportunities and education, training and development activities were regarded as the organisational strategies with the strongest impact on career progress. The literature was confirmed regarding top management support, an organisational culture conducive to women's advancement, mentorship programmes and a few career development initiatives. Although more than half of the respondents had been exposed to employment equity and affirmative action programmes, they were perceived to have only little to moderate impact on career progress. This was also the case with diversity management programmes. Flexible work arrangements, career adaptation schemes and childcare facilities and programmes were seen as having had little impact on the respondents' career advancement. Only a few of the organisational practices to support women balancing family and work responsibilities were utilised by the respondents' employers. Respondents perceived personal strategies as having greater value than organisational strategies in their progress to executive levels.
- Full Text:
- Date Issued: 2003
An investigation into strategies which enable South African women to break through the glass ceiling
- Authors: Peens, Maritha
- Date: 2003
- Subjects: Women executives -- South Africa , Women employees -- Promotions -- South Africa , Sex discrimination in employement -- South Africa , Sex discrimination against women -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10898 , http://hdl.handle.net/10948/135 , Women executives -- South Africa , Women employees -- Promotions -- South Africa , Sex discrimination in employement -- South Africa , Sex discrimination against women -- South Africa
- Description: The objective of this study was to identify the strategies (personal and organisational) that would enable South African women to break through the glass ceiling. A questionaire was designed based on the strategies found in a literature study on the topic and used to gather inputs from executive women in South Africa. A combination of snowball and self-selection sampling was used. The questionaire was sent to 138 potential respondents, mostly by means of electronic mail. Of the 47 completed questionairs returned, 44 could be used. These were processed and anaylsed using Microsoft Excel spreadsheets and the STATISTICA Version 6 software. In generaL, support was found for personal strategies pertaining to career management, networking (especially the relationship building activities), the reconciliation of home and work responsibilities with the emphasis on building a support system, education, business and organisational insught, skills development and increased input, but not for the assimilation of masculine attributes. Networking opportunities and education, training and development activities were regarded as the organisational strategies with the strongest impact on career progress. The literature was confirmed regarding top management support, an organisational culture conducive to women's advancement, mentorship programmes and a few career development initiatives. Although more than half of the respondents had been exposed to employment equity and affirmative action programmes, they were perceived to have only little to moderate impact on career progress. This was also the case with diversity management programmes. Flexible work arrangements, career adaptation schemes and childcare facilities and programmes were seen as having had little impact on the respondents' career advancement. Only a few of the organisational practices to support women balancing family and work responsibilities were utilised by the respondents' employers. Respondents perceived personal strategies as having greater value than organisational strategies in their progress to executive levels.
- Full Text:
- Date Issued: 2003
An investigation into the application of the IEEE 1394 high performance serial bus to sound installation contro
- Authors: Klinkradt, Bradley Hugh
- Date: 2003 , 2013-05-24
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4612 , http://hdl.handle.net/10962/d1004899 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using existing IP-based control and monitoring protocols within professional audio installations utilising IEEE 1394 technology. Current control and monitoring technologies are examined, and the characteristics common to all are extracted and compiled into an object model. This model forms the foundation for a set of evaluation criteria against which current and future control and monitoring protocols may be measured. Protocols considered include AV/C, MIDI, QSC-24, and those utilised within the UPnP architecture. As QSC-24 and the UPnP architecture are IP-based, the facilities required to transport IP datagrams over the IEEE 1394 bus are investigated and implemented. Example QSC-24 and UPnP architecture implementations are described, which permit the control and monitoring of audio devices over the IEEE 1394 network using these IP-based technologies. The way forward for the control and monitoring of professional audio devices within installations is considered, and recommendations are provided. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
- Authors: Klinkradt, Bradley Hugh
- Date: 2003 , 2013-05-24
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4612 , http://hdl.handle.net/10962/d1004899 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using existing IP-based control and monitoring protocols within professional audio installations utilising IEEE 1394 technology. Current control and monitoring technologies are examined, and the characteristics common to all are extracted and compiled into an object model. This model forms the foundation for a set of evaluation criteria against which current and future control and monitoring protocols may be measured. Protocols considered include AV/C, MIDI, QSC-24, and those utilised within the UPnP architecture. As QSC-24 and the UPnP architecture are IP-based, the facilities required to transport IP datagrams over the IEEE 1394 bus are investigated and implemented. Example QSC-24 and UPnP architecture implementations are described, which permit the control and monitoring of audio devices over the IEEE 1394 network using these IP-based technologies. The way forward for the control and monitoring of professional audio devices within installations is considered, and recommendations are provided. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
An investigation into the biological treatment of platinum refinery effluent using the plant Azolla Filiculoides
- Authors: Marran, Vernon Edward
- Date: 2003
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193453 , vital:45333
- Description: In order to understand the effects of metals contained in effluent and to define effluent quality suitable for safe discharge to natural water streams, it is essential to understand the effects of the interaction of metal ions with plants. The availability of metal ions and their ability to bind to plants are dependent on the chemical speciation of metals and on the biological factors governing the availability of metals within the plant cells. This thesis will address both aspects and thereby propose a combination of an appropriate chemical and biological approach to the investigation of bioaccumulation of the plant Azolla Filiculoides. Laboratory studies have shown that varying concentrations of free metal ions in solution determine efficiency of metal uptake and that metal toxicity can also be detrimental to plant life and efficiency of metal recovery from solution. Many questions however, remain unanswered with regard to the application of a biological treatment for effluent discharge. This thesis includes the determination of metal speciation combined with the study of bioaccumulation of metals in plants and their effects from test- work utilising effluent generated from a Precious Metals Refinery (PMR). Plant species are known to differ widely in their tolerance to metals, however despite an abundant knowledge on molecular, biochemical and physiological effects of metals to plants, only a few general principles have been proposed to guide the prediction of tolerance differences. The properties of protective cellular responses as well as of the molecular target sites are important components in determining the intrinsic tolerance of a particular species to a metal. The role of the whole assembly of cellular ligands in buffering metal ions within the cells will be evaluated. Standard preparation methods combined with use of Inductively Coupled Plasma Emission Spectrophotometer (1CP) used for analytical analysis will be included to reflect analytical data in providing evidence to support a conclusion. The outcome of the test work utilising the aquatic plant Azoila has proven that it can be used as a process step to re-mediate effluent generated from Precious Metal Refining operations. This process offers an alternative to the classical chemical methods widely used in the Precious Metals Refining industry proving economically viable and ensuring environmental sustainability in comparison to the current known methods of effluent treatment. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2003
- Full Text:
- Date Issued: 2003
- Authors: Marran, Vernon Edward
- Date: 2003
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193453 , vital:45333
- Description: In order to understand the effects of metals contained in effluent and to define effluent quality suitable for safe discharge to natural water streams, it is essential to understand the effects of the interaction of metal ions with plants. The availability of metal ions and their ability to bind to plants are dependent on the chemical speciation of metals and on the biological factors governing the availability of metals within the plant cells. This thesis will address both aspects and thereby propose a combination of an appropriate chemical and biological approach to the investigation of bioaccumulation of the plant Azolla Filiculoides. Laboratory studies have shown that varying concentrations of free metal ions in solution determine efficiency of metal uptake and that metal toxicity can also be detrimental to plant life and efficiency of metal recovery from solution. Many questions however, remain unanswered with regard to the application of a biological treatment for effluent discharge. This thesis includes the determination of metal speciation combined with the study of bioaccumulation of metals in plants and their effects from test- work utilising effluent generated from a Precious Metals Refinery (PMR). Plant species are known to differ widely in their tolerance to metals, however despite an abundant knowledge on molecular, biochemical and physiological effects of metals to plants, only a few general principles have been proposed to guide the prediction of tolerance differences. The properties of protective cellular responses as well as of the molecular target sites are important components in determining the intrinsic tolerance of a particular species to a metal. The role of the whole assembly of cellular ligands in buffering metal ions within the cells will be evaluated. Standard preparation methods combined with use of Inductively Coupled Plasma Emission Spectrophotometer (1CP) used for analytical analysis will be included to reflect analytical data in providing evidence to support a conclusion. The outcome of the test work utilising the aquatic plant Azoila has proven that it can be used as a process step to re-mediate effluent generated from Precious Metal Refining operations. This process offers an alternative to the classical chemical methods widely used in the Precious Metals Refining industry proving economically viable and ensuring environmental sustainability in comparison to the current known methods of effluent treatment. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2003
- Full Text:
- Date Issued: 2003
An investigation into the challenges facing the financial manager in South African manufacturing organisations and the ways of surmounting these challenges
- Authors: Diedericks, Petrus Philip
- Date: 2003
- Subjects: Industrial management -- South Africa -- Finance , Business enterprises -- South Africa -- Finance , Financial executives -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10876 , http://hdl.handle.net/10948/244 , Industrial management -- South Africa -- Finance , Business enterprises -- South Africa -- Finance , Financial executives -- South Africa
- Description: The research problem addressed in this study was to determine the challenges facing the financial manager in the manufacturing organisation and the possible ways of surmounting these challenges. To achieve this objective, relevant literature was reviewed and an empirical survey conducted. The main challenges identified are discussed under the following headings: · Regulatory requirements; · Information age; · Employees; · Economic environment; Each challenge was broken down into sub-challenges that were analysed using literature identified in the literature study. This information was used to develop a questionnaire to test the degree to which financial managers working for manufacturing organisations are challenged. The empirical results obtained indicate a strong concurrence with the literature study emphasising the importance of the identified challenges and the best possible ways of surmounting these challenges.
- Full Text:
- Date Issued: 2003
- Authors: Diedericks, Petrus Philip
- Date: 2003
- Subjects: Industrial management -- South Africa -- Finance , Business enterprises -- South Africa -- Finance , Financial executives -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10876 , http://hdl.handle.net/10948/244 , Industrial management -- South Africa -- Finance , Business enterprises -- South Africa -- Finance , Financial executives -- South Africa
- Description: The research problem addressed in this study was to determine the challenges facing the financial manager in the manufacturing organisation and the possible ways of surmounting these challenges. To achieve this objective, relevant literature was reviewed and an empirical survey conducted. The main challenges identified are discussed under the following headings: · Regulatory requirements; · Information age; · Employees; · Economic environment; Each challenge was broken down into sub-challenges that were analysed using literature identified in the literature study. This information was used to develop a questionnaire to test the degree to which financial managers working for manufacturing organisations are challenged. The empirical results obtained indicate a strong concurrence with the literature study emphasising the importance of the identified challenges and the best possible ways of surmounting these challenges.
- Full Text:
- Date Issued: 2003
An investigation into the current and potential benefits of tourism-based development in the Albany and Peddie districts
- Authors: Klinkradt, Mary Louise
- Date: 2003 , 2013-05-27
- Subjects: Tourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Grahamstown , Tourism -- South Africa -- Peddie , Ecotourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Eastern Cape -- Management , Tourism -- Social aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:4811 , http://hdl.handle.net/10962/d1004904 , Tourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Grahamstown , Tourism -- South Africa -- Peddie , Ecotourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Eastern Cape -- Management , Tourism -- Social aspects -- South Africa -- Eastern Cape
- Description: This research considers the relationship between tourism and development, and how tourism can be used as a means of promoting development. In order to explore this relationship, two districts in the Eastern Cape province of South Africa, the Albany and Peddie Districts have been selected as case study areas. Both the Albany and Peddie Districts are in need of development which can meet the economic and social development of the districts. One such option for the two districts is tourism-based development. This research examines the current status of tourism in both districts through the use of secondary data analysis and primary data gathered from questionnaires and interviews undertaken with tourists and representatives of key stakeholders in the tourism industry. This data was used to establish the current and future potential of tourism in the districts in terms of the availability and diversity of attractions and the tourism assets and facilities in the districts. It was also used to determine whether or not tourism, by promoting infrastructural and economic development, may lead to the socio-economic upliftment of the Albany and Peddie Districts. The results obtained from this research highlight the significant lack of tourism infrastructure in the Peddie District, and the reality that the tourism potential of the district remains untapped. With the marketing and promotion of tourism to the district, and the associated tourist requirements such as accommodation, and other facilities, tourism does hold a potential key to the socio-economic development of the district. The Albany District, however, has a well-established tourism industry, but the development spin-ofts are minimal, and the potential for further tourism-based development in the future would therefore appear to be somewhat limited. A GIS (Geographic Information System) was use to determine and detail possible tourism routes, a final outcome of the investigation being the proposal of two tourism routes to draw people into and through the study area, based on the current assets and attractions of the two districts. These routes highlight one of the options available in the districts to promote much needed development in the two districts through the use of the tourism industry. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
- Authors: Klinkradt, Mary Louise
- Date: 2003 , 2013-05-27
- Subjects: Tourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Grahamstown , Tourism -- South Africa -- Peddie , Ecotourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Eastern Cape -- Management , Tourism -- Social aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:4811 , http://hdl.handle.net/10962/d1004904 , Tourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Grahamstown , Tourism -- South Africa -- Peddie , Ecotourism -- South Africa -- Eastern Cape , Tourism -- South Africa -- Eastern Cape -- Management , Tourism -- Social aspects -- South Africa -- Eastern Cape
- Description: This research considers the relationship between tourism and development, and how tourism can be used as a means of promoting development. In order to explore this relationship, two districts in the Eastern Cape province of South Africa, the Albany and Peddie Districts have been selected as case study areas. Both the Albany and Peddie Districts are in need of development which can meet the economic and social development of the districts. One such option for the two districts is tourism-based development. This research examines the current status of tourism in both districts through the use of secondary data analysis and primary data gathered from questionnaires and interviews undertaken with tourists and representatives of key stakeholders in the tourism industry. This data was used to establish the current and future potential of tourism in the districts in terms of the availability and diversity of attractions and the tourism assets and facilities in the districts. It was also used to determine whether or not tourism, by promoting infrastructural and economic development, may lead to the socio-economic upliftment of the Albany and Peddie Districts. The results obtained from this research highlight the significant lack of tourism infrastructure in the Peddie District, and the reality that the tourism potential of the district remains untapped. With the marketing and promotion of tourism to the district, and the associated tourist requirements such as accommodation, and other facilities, tourism does hold a potential key to the socio-economic development of the district. The Albany District, however, has a well-established tourism industry, but the development spin-ofts are minimal, and the potential for further tourism-based development in the future would therefore appear to be somewhat limited. A GIS (Geographic Information System) was use to determine and detail possible tourism routes, a final outcome of the investigation being the proposal of two tourism routes to draw people into and through the study area, based on the current assets and attractions of the two districts. These routes highlight one of the options available in the districts to promote much needed development in the two districts through the use of the tourism industry. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
An investigation into the executive mayoral system, with reference to the Nelson Mandela Metropolitan Municipality
- Authors: Nkayitshana, Zweledinga
- Date: 2003
- Subjects: Mayors -- South Africa -- Port Elizabeth , Local government -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MTech (Public Management)
- Identifier: vital:10775 , http://hdl.handle.net/10948/246 , Mayors -- South Africa -- Port Elizabeth , Local government -- South Africa -- Port Elizabeth
- Description: In this mini-dissertation, a study is undertaken for an investigation into the Executive Mayoral System with reference to the Nelson Mandela Metropolitan Municipality. The mini-dissertation comprises of five chapters. The study is based on the assumption that the introduction of an executive mayoral system will enhance the decision-making and policy-making processes at the Nelson Mandela Metropolitan Municipality. This is also based on the assumption that all local authorities and the Nelson Mandela Metropolitan Municipality in particular are faced with challenges of developmental local government. The Executive Mayoral System, therefore, is expected to provide possible solutions and avenues to promote and improve socio-economic development and service delivery to strengthen the local tax base. Another challenging aspect is the capacity building for the staff members of the Nelson Mandela Metropolitan Municipality especially the Executive Mayor who has all the powers vested in him. The main objectives of the research include, inter alia, to provide a brief theoretical background explanation regarding the reasons for the existence of local authorities and restructuring of local government in South Africa. To investigate and report on the implementation of the new mandate for local government with reference to the Executive Mayoral System at the Nelson Mandela Metropolitan Municipality. To investigate whether the Executive Mayoral System at the NMMM will contribute towards efficient and effective service delivery. This will be followed by the impact of the Metropole to promote and encourage community involvement on all the programmes of the municipality. This investigation will ensure that the Nelson Mandela Metropolitan Municipality provides conducive environment for socio-economic development and achieve the national economic strategy under Growth, Employment and Redistribution (GEAR) policy. To bring about experiences from other countries and learn from those experiences based on their approach to the Executive Mayoral System. An overview of the legislative framework and an explanation of selected policies for the Executive Mayoral System are made. Finally, a number of conclusions that were arrived during the study, followed by various recommendations are made. These are based on the qualitative research analysis in order to come up with solutions of ensuring sustainable service delivery with the Executive Mayoral System.
- Full Text:
- Date Issued: 2003
- Authors: Nkayitshana, Zweledinga
- Date: 2003
- Subjects: Mayors -- South Africa -- Port Elizabeth , Local government -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MTech (Public Management)
- Identifier: vital:10775 , http://hdl.handle.net/10948/246 , Mayors -- South Africa -- Port Elizabeth , Local government -- South Africa -- Port Elizabeth
- Description: In this mini-dissertation, a study is undertaken for an investigation into the Executive Mayoral System with reference to the Nelson Mandela Metropolitan Municipality. The mini-dissertation comprises of five chapters. The study is based on the assumption that the introduction of an executive mayoral system will enhance the decision-making and policy-making processes at the Nelson Mandela Metropolitan Municipality. This is also based on the assumption that all local authorities and the Nelson Mandela Metropolitan Municipality in particular are faced with challenges of developmental local government. The Executive Mayoral System, therefore, is expected to provide possible solutions and avenues to promote and improve socio-economic development and service delivery to strengthen the local tax base. Another challenging aspect is the capacity building for the staff members of the Nelson Mandela Metropolitan Municipality especially the Executive Mayor who has all the powers vested in him. The main objectives of the research include, inter alia, to provide a brief theoretical background explanation regarding the reasons for the existence of local authorities and restructuring of local government in South Africa. To investigate and report on the implementation of the new mandate for local government with reference to the Executive Mayoral System at the Nelson Mandela Metropolitan Municipality. To investigate whether the Executive Mayoral System at the NMMM will contribute towards efficient and effective service delivery. This will be followed by the impact of the Metropole to promote and encourage community involvement on all the programmes of the municipality. This investigation will ensure that the Nelson Mandela Metropolitan Municipality provides conducive environment for socio-economic development and achieve the national economic strategy under Growth, Employment and Redistribution (GEAR) policy. To bring about experiences from other countries and learn from those experiences based on their approach to the Executive Mayoral System. An overview of the legislative framework and an explanation of selected policies for the Executive Mayoral System are made. Finally, a number of conclusions that were arrived during the study, followed by various recommendations are made. These are based on the qualitative research analysis in order to come up with solutions of ensuring sustainable service delivery with the Executive Mayoral System.
- Full Text:
- Date Issued: 2003
An investigation into the feeding biology and factors influencing the population dynamics of Terebrasabella heterouncinata (Polychaeta: Sabellidae), a problematic tube-dwelling polychaete in farmed abalone in South Africa
- Authors: Chalmers, Russell
- Date: 2003
- Subjects: Polychaeta -- South Africa , Sabellidae -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5291 , http://hdl.handle.net/10962/d1005136 , Polychaeta -- South Africa , Sabellidae -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Description: Since the discovery of a new species of sabellid worm in 1993, the Californian and South African abalone industries have experienced increasing shell breakage and reduced growth rates of abalone, resulting in reduced market value of product. This polychaete worm can reach very high infestation levels. It was described as Terebrasabella heterouncinata in 1999, having originated from the South African coastline where it had been observed on several wild mollusc species. Although not a shell borer, it occupies tubes on the growing edge which are formed by deposition of nacreous shell over sabellid larvae by the host abalone. Heavy sabellid infestation levels have placed the economic viability of several South African farms under threat. Past research methods have not been successful in establishing effective means of eradication or control, partly due to the lack of knowledge of basic biological information on this species. This study forms the first part of an ongoing research project into the biology of terebrasabella heterouncinata. Abalone farms in South African utilise two main diets in abalone culture. An artificial formulated feed, Abfeed, is produced in South Africa and is used by the majority of farms as it increases abalone growth rate. Kelp, a natural diet of abalone, is harvested and also used as a feed. Farmers have observed higher sabellid infestation levels on Abfeed-fed abalone and suspect that diet may be an important factor influencing sabellid infestation. Abalone stocking density has also been identified as a potential factor influencing sabellid population growth on commercial farms. In order to better understand sabellid nutrition, the feeding behaviour of the sabellid in response to suspended solids of various particle size classes from both abalone diets were investigated. Both the effect of abalone diet and stocking density and their effects on sabellid morphometrics were quantified. The proximate composition and particle size distribution of suspended-solids present within kelp and Abfeed abalone raceways were also quantified. Results indicate that sabellid feeding follows no structured behavioural pattern for both abalone diets. The quantity of suspended solids in kelp raceways was greater than in Abfeed raceways (p<0.02) while there was no difference in particulate level between three abalone stocking densities (p>0.05). Protein (p<0.0001) and energy (p<0.0.1) levels of suspended solids were significantly greater in raceways dedicated to feeding Abfeed. The infestation level (number of tubes/centimetre on the grwoing edge) was significantly higher (p<0.001) in Abfeed-fed abalone. The morphometrics of the sabellids indicated that sabellids from Abfeed-fed abalone were larger in various body measurements: length (p<0.00001); neck width (p<0.001); base width (p<0.001); and surface area (p<0.001). This study suggests that abalone diet has an important influence on the infestation level and size of sabellids and that this is likely to be due to the fragmentation and leaching of nutrients from the artificially enriched commercial abalone diet.
- Full Text:
- Date Issued: 2003
- Authors: Chalmers, Russell
- Date: 2003
- Subjects: Polychaeta -- South Africa , Sabellidae -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5291 , http://hdl.handle.net/10962/d1005136 , Polychaeta -- South Africa , Sabellidae -- South Africa , Abalones -- Feeding and feeds -- South Africa
- Description: Since the discovery of a new species of sabellid worm in 1993, the Californian and South African abalone industries have experienced increasing shell breakage and reduced growth rates of abalone, resulting in reduced market value of product. This polychaete worm can reach very high infestation levels. It was described as Terebrasabella heterouncinata in 1999, having originated from the South African coastline where it had been observed on several wild mollusc species. Although not a shell borer, it occupies tubes on the growing edge which are formed by deposition of nacreous shell over sabellid larvae by the host abalone. Heavy sabellid infestation levels have placed the economic viability of several South African farms under threat. Past research methods have not been successful in establishing effective means of eradication or control, partly due to the lack of knowledge of basic biological information on this species. This study forms the first part of an ongoing research project into the biology of terebrasabella heterouncinata. Abalone farms in South African utilise two main diets in abalone culture. An artificial formulated feed, Abfeed, is produced in South Africa and is used by the majority of farms as it increases abalone growth rate. Kelp, a natural diet of abalone, is harvested and also used as a feed. Farmers have observed higher sabellid infestation levels on Abfeed-fed abalone and suspect that diet may be an important factor influencing sabellid infestation. Abalone stocking density has also been identified as a potential factor influencing sabellid population growth on commercial farms. In order to better understand sabellid nutrition, the feeding behaviour of the sabellid in response to suspended solids of various particle size classes from both abalone diets were investigated. Both the effect of abalone diet and stocking density and their effects on sabellid morphometrics were quantified. The proximate composition and particle size distribution of suspended-solids present within kelp and Abfeed abalone raceways were also quantified. Results indicate that sabellid feeding follows no structured behavioural pattern for both abalone diets. The quantity of suspended solids in kelp raceways was greater than in Abfeed raceways (p<0.02) while there was no difference in particulate level between three abalone stocking densities (p>0.05). Protein (p<0.0001) and energy (p<0.0.1) levels of suspended solids were significantly greater in raceways dedicated to feeding Abfeed. The infestation level (number of tubes/centimetre on the grwoing edge) was significantly higher (p<0.001) in Abfeed-fed abalone. The morphometrics of the sabellids indicated that sabellids from Abfeed-fed abalone were larger in various body measurements: length (p<0.00001); neck width (p<0.001); base width (p<0.001); and surface area (p<0.001). This study suggests that abalone diet has an important influence on the infestation level and size of sabellids and that this is likely to be due to the fragmentation and leaching of nutrients from the artificially enriched commercial abalone diet.
- Full Text:
- Date Issued: 2003
An investigation into the induction of oxidative stress and apoptosis by microcystin-LR in the CaCo2 cell line and intestinal tract of Balb/c mice
- Authors: Botha, Nicolette
- Date: 2003
- Subjects: Microcystis aeruginosa -- Toxicology , Apoptosis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11066 , http://hdl.handle.net/10948/349 , Microcystis aeruginosa -- Toxicology , Apoptosis
- Description: This study reports the findings on the effect of Microcystin-LR (MCLR) on the gastrointestinal tract cells of mice and on two different cell lines, Caco2 and MCF-7. The cyanobacterium Microcystis aeruginosa produces the potent toxin, MCLR. This toxin has been implicated in a number of cases of ill-health. It was decided to investigate whether microcystin-LR induced apoptosis in the gastrointestinal tract of mice and also which possible mechanisms were involved in the induction in vitro. Balb/c mice were given a 75% LD50 intraperitoneal dose of pure microcystin -LR and sacrificed at 8, 16, 24 and 32 hours post-exposure. The small intestinal sections were stained with haematoxylin and eosin and examined for apoptotic cells. There was a time-dependent increase in the number of apoptotic cells with most in the duodenum and the jejunum. No change in glycogen content was evident at 24 hours post exposure when PAS-stained sections were examined. To determine that microcystin was the agent responsible for the changes, fluoroscein isothiocyanate (FITC) immunostaining for the toxin was done on the sections. Apoptosis in vitro was investigated in Caco2, a cell line that behaves like normal enterocytes when the cells are differentiated at confluency, and MCF-7, a breast cancer cell line deficient in pro-caspase-3, cells by 3-[dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays and by staining with DAPI and Rhodamine 123. MCLR exposure induced apoptosis, as seen in decreased cell viability and increased leakage of LDH, as well as mitochondrial damage shown by Rhodamine staining. The MCF-7 cells, deficient in pro-caspase-3, and Caco2 cells did not show cleavage of poly(ADP)ribose polymerase (PARP) after exposure to 50μM MCLR after 72 hours exposure. Both micro- and milli-calpain activity was however significantly increased in both cell lines exposed to the toxin. There was a significant increase in H2O2, one of the key reactive oxygen species, production during the first 30 minutes that the cells were exposed to 50 mM MCLR.
- Full Text:
- Date Issued: 2003
- Authors: Botha, Nicolette
- Date: 2003
- Subjects: Microcystis aeruginosa -- Toxicology , Apoptosis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11066 , http://hdl.handle.net/10948/349 , Microcystis aeruginosa -- Toxicology , Apoptosis
- Description: This study reports the findings on the effect of Microcystin-LR (MCLR) on the gastrointestinal tract cells of mice and on two different cell lines, Caco2 and MCF-7. The cyanobacterium Microcystis aeruginosa produces the potent toxin, MCLR. This toxin has been implicated in a number of cases of ill-health. It was decided to investigate whether microcystin-LR induced apoptosis in the gastrointestinal tract of mice and also which possible mechanisms were involved in the induction in vitro. Balb/c mice were given a 75% LD50 intraperitoneal dose of pure microcystin -LR and sacrificed at 8, 16, 24 and 32 hours post-exposure. The small intestinal sections were stained with haematoxylin and eosin and examined for apoptotic cells. There was a time-dependent increase in the number of apoptotic cells with most in the duodenum and the jejunum. No change in glycogen content was evident at 24 hours post exposure when PAS-stained sections were examined. To determine that microcystin was the agent responsible for the changes, fluoroscein isothiocyanate (FITC) immunostaining for the toxin was done on the sections. Apoptosis in vitro was investigated in Caco2, a cell line that behaves like normal enterocytes when the cells are differentiated at confluency, and MCF-7, a breast cancer cell line deficient in pro-caspase-3, cells by 3-[dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays and by staining with DAPI and Rhodamine 123. MCLR exposure induced apoptosis, as seen in decreased cell viability and increased leakage of LDH, as well as mitochondrial damage shown by Rhodamine staining. The MCF-7 cells, deficient in pro-caspase-3, and Caco2 cells did not show cleavage of poly(ADP)ribose polymerase (PARP) after exposure to 50μM MCLR after 72 hours exposure. Both micro- and milli-calpain activity was however significantly increased in both cell lines exposed to the toxin. There was a significant increase in H2O2, one of the key reactive oxygen species, production during the first 30 minutes that the cells were exposed to 50 mM MCLR.
- Full Text:
- Date Issued: 2003
An investigation into the neuroprotective properties of curcumin
- Authors: Daniel, Sheril
- Date: 2003
- Subjects: Turmeric -- Therapeutic use , Nervous system -- Degeneration -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3753 , http://hdl.handle.net/10962/d1003231 , Turmeric -- Therapeutic use , Nervous system -- Degeneration -- Prevention
- Description: An increasing number of studies show that nutritional antioxidants such as vitamin E and polyphenols are capable of blocking neuronal death in vitro and may have therapeutic properties in animal models of neurodegenerative diseases including Alzheimer’s and Parkinson’s diseases. In the present study, the neuroprotective ability of one such polyphenolic antioxidant, curcumin, was investigated. Curcumin is the yellow curry spice derived from turmeric, and is widely used as a dietary component and herbal medicine in India. Most neurological disorders are postulated to have an oxidative or excitototoxic basis. Thus the effects of curcumin on oxidative stress in the rat brain were investigated. Curcumin, administered to the rat in vivo and in vitro, was able to exert protective effects on oxidative damage in the brain, induced by cyanide, a mitochondrial inhibitor. Curcumin also offered protection against quinolinic acid induced lipid peroxidation, and this protection was extended to lipid peroxidation induced by metals such as lead and cadmium in the rat brain. Experiments conducted on the pineal gland revealed an increased production of the neuroprotective hormone melatonin in presence of curcumin in vivo. The hippocampus is functionally related to vital behaviour and intellectual activities and is known to be a primary target for neuronal degeneration in the brains of patients with Alzheimer’s disease. Histological studies were undertaken to assess the effects of curcumin on lead induced toxicity on the rat hippocampus, the results of which show that curcumin affords significant protection to the hippocampus of the lead treated rats. This study also sought to elucidate possible mechanisms by which curcumin exerts its neuroprotective capabilities. Curcumin was found to inhibit the action of cyanide on the mitochondrial electron transport chain, one of the most common sources of free radicals. Electrochemical, UV/VIS and Infrared spectroscopy were used to characterise interactions between curcumin and the metals lead, cadmium, iron (II) and iron (III). Curcumin was shown to directly chelate these metals with the formation and isolation of two new curcumin complexes with lead, and one complex each with cadmium and iron (III). These results suggest chelation of toxic metals as a mechanism of neuroprotection afforded by curcumin. The need for neuroprotective agents is urgent considering the rapid rise in the elderly population and the proportionate increase in neurological disorders. The findings of this study indicate that curcumin, a well-established dietary antioxidant, is capable of playing a bigger role in neuroprotection, which needs to be further explored and exploited.
- Full Text:
- Date Issued: 2003
- Authors: Daniel, Sheril
- Date: 2003
- Subjects: Turmeric -- Therapeutic use , Nervous system -- Degeneration -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3753 , http://hdl.handle.net/10962/d1003231 , Turmeric -- Therapeutic use , Nervous system -- Degeneration -- Prevention
- Description: An increasing number of studies show that nutritional antioxidants such as vitamin E and polyphenols are capable of blocking neuronal death in vitro and may have therapeutic properties in animal models of neurodegenerative diseases including Alzheimer’s and Parkinson’s diseases. In the present study, the neuroprotective ability of one such polyphenolic antioxidant, curcumin, was investigated. Curcumin is the yellow curry spice derived from turmeric, and is widely used as a dietary component and herbal medicine in India. Most neurological disorders are postulated to have an oxidative or excitototoxic basis. Thus the effects of curcumin on oxidative stress in the rat brain were investigated. Curcumin, administered to the rat in vivo and in vitro, was able to exert protective effects on oxidative damage in the brain, induced by cyanide, a mitochondrial inhibitor. Curcumin also offered protection against quinolinic acid induced lipid peroxidation, and this protection was extended to lipid peroxidation induced by metals such as lead and cadmium in the rat brain. Experiments conducted on the pineal gland revealed an increased production of the neuroprotective hormone melatonin in presence of curcumin in vivo. The hippocampus is functionally related to vital behaviour and intellectual activities and is known to be a primary target for neuronal degeneration in the brains of patients with Alzheimer’s disease. Histological studies were undertaken to assess the effects of curcumin on lead induced toxicity on the rat hippocampus, the results of which show that curcumin affords significant protection to the hippocampus of the lead treated rats. This study also sought to elucidate possible mechanisms by which curcumin exerts its neuroprotective capabilities. Curcumin was found to inhibit the action of cyanide on the mitochondrial electron transport chain, one of the most common sources of free radicals. Electrochemical, UV/VIS and Infrared spectroscopy were used to characterise interactions between curcumin and the metals lead, cadmium, iron (II) and iron (III). Curcumin was shown to directly chelate these metals with the formation and isolation of two new curcumin complexes with lead, and one complex each with cadmium and iron (III). These results suggest chelation of toxic metals as a mechanism of neuroprotection afforded by curcumin. The need for neuroprotective agents is urgent considering the rapid rise in the elderly population and the proportionate increase in neurological disorders. The findings of this study indicate that curcumin, a well-established dietary antioxidant, is capable of playing a bigger role in neuroprotection, which needs to be further explored and exploited.
- Full Text:
- Date Issued: 2003
An investigation into the occurrence of major abscess causing bacteria at the law meat exporting abattoir in the Northern Cape province of South Africa
- Authors: Delport, Riëtte
- Date: 2003
- Subjects: Abscess , Meat -- Microbiology , Slaughtering and slaughter-houses -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10971 , http://hdl.handle.net/10948/249 , Abscess , Meat -- Microbiology , Slaughtering and slaughter-houses -- South Africa -- Northern Cape
- Description: The main objectives of this study can be divided into four categories: a) The determination of the presence of abscesses in carcasses. b) The determination whether the abscesses are area bound. c) The determination of the causative bacteria which is responsible for abscess formation. d) The determination of the economic impact due to carcass rejections and trimmings. The research area consists of the biggest part of the Northern Cape province, which can further be divided into three main production areas, namely Groblershoop, Gordonia and Hantam. The Groblershoop area includes Groblershoop and the surrounding districts. The Gordonia area includes Upington and the Kalahari. The Hantam area includes Calvinia, Springbok and the other districts bordering the areas. All the carcasses were slaughtered at an export abattoir, namely LAW, which is situated in Groblershoop. The Upington veterinary laboratory bacteriologically cultured the abscess material and the results were processed and noted. The following results were prominent: a) It was determined that abscesses did occur in carcasses. b) It was determined that in the Hantam main production area the prevalence of abscesses is the highest, although the slaughter numbers are the lowest. c) It was determined that the bacterium that was responsible for most of the abscesses was Escherichia coli. d) It was determined that the total occurrence of bacteria did not have a significant economic impact, because there were not many carcass rejections due to abscesses. The economic impact, however, of the value of the total rejections, might become a problem.
- Full Text:
- Date Issued: 2003
- Authors: Delport, Riëtte
- Date: 2003
- Subjects: Abscess , Meat -- Microbiology , Slaughtering and slaughter-houses -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10971 , http://hdl.handle.net/10948/249 , Abscess , Meat -- Microbiology , Slaughtering and slaughter-houses -- South Africa -- Northern Cape
- Description: The main objectives of this study can be divided into four categories: a) The determination of the presence of abscesses in carcasses. b) The determination whether the abscesses are area bound. c) The determination of the causative bacteria which is responsible for abscess formation. d) The determination of the economic impact due to carcass rejections and trimmings. The research area consists of the biggest part of the Northern Cape province, which can further be divided into three main production areas, namely Groblershoop, Gordonia and Hantam. The Groblershoop area includes Groblershoop and the surrounding districts. The Gordonia area includes Upington and the Kalahari. The Hantam area includes Calvinia, Springbok and the other districts bordering the areas. All the carcasses were slaughtered at an export abattoir, namely LAW, which is situated in Groblershoop. The Upington veterinary laboratory bacteriologically cultured the abscess material and the results were processed and noted. The following results were prominent: a) It was determined that abscesses did occur in carcasses. b) It was determined that in the Hantam main production area the prevalence of abscesses is the highest, although the slaughter numbers are the lowest. c) It was determined that the bacterium that was responsible for most of the abscesses was Escherichia coli. d) It was determined that the total occurrence of bacteria did not have a significant economic impact, because there were not many carcass rejections due to abscesses. The economic impact, however, of the value of the total rejections, might become a problem.
- Full Text:
- Date Issued: 2003
An investigation into the physico-chemical and neuroprotective properties of melatonin and 6-hydroxymelatonin
- Authors: Maharaj, Deepa Sukhdev
- Date: 2003
- Subjects: Melatonin Nervous system -- Degeneration -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3768 , http://hdl.handle.net/10962/d1003246
- Description: Until the beginning of this decade the antioxidant, melatonin, had been considered as little more than a tranquilizing hormone, responsible for regulating certain circadian and circannual rhythms. However, it is the discovery of melatonin as a free radical scavenger that has generated the most interest in recent years. The reduction of melatonin with age has been associated with neurodegenerative diseases such as Alzheimer’s disease (AD)and therefore, melatonin has been implicated to have an important clinical role in neuroprotection. Thus, for several years melatonin has attracted increasing attention from the general press with many advertisements touting this indoleamine to act as an aphrodisiac, rejuvenator, protector against diseases and a general wonder drug. However, melatonin formulations appear with no labelling for the correct storage conditions, dosage and side effects, as well as no control for purity and self-medicating with an unregulated product. In addition, there is much controversy surrounding the antioxidative properties of the indolemaine, 6-hydroxymelatonin (6-OHM). Therefore, the first part of this study aims to elucidate the physico-chemical and various stability characteristics of the pineal antioxidant, melatonin, while the second part is devoted to investigating the neuroprotective properties of the primary hepatic metabolite of melatonin, 6-OHM. The physical properties of melatonin were determined using various chemical techniques. This information served to both characterize and confirm the identity of melatonin raw material used in this study. In addition, this information serves to be essential as the physical properties of melatonin have not been reported in detail in literature, to date. Thereafter, using a validated high performance liquid chromatography (HPLC) method, the various physico-chemical and stability characteristics of melatonin were determined. Melatonin was shown to be extremely lipophilic, while the hygroscopic study indicates that melatonin raw material is extremely hygroscopic at temperatures above 40°C, whereas melatonin tablets are hygroscopic when left out of the original container. This study highlights the need for consumers to be aware of the proper storage of melatonin tablets to improve the stability and ensure long term integrity of the compound. Since, melatonin is most often administered orally, thus exposing it to a large variations in pH, within the gastrointestinal tract, it was decided to investigate the stability of melatonin over a range of pH’s and temperatures. The findings imply that melatonin is relatively stable at body temperature when ingested orally and that orally administered slow release preparations of melatonin should be relatively stable and therefore exhibit favourable bioavailability. However melatonin was shown to be unstable in solution. This provides important information and a challenge to the formulators of this drug substance in a liquid dosage form. An assessment of the photostability of melatonin dosage forms using International Committee on Harmonization (ICH) conditions revealed melatonin to be light sensitive and thus indicates a need for careful consideration of the packaging of these drug products. In addition a detailed assessment of the photochemistry and photoproducts formed during the UV photodegradation of melatonin is reported. Melatonin is shown to rapidly degrade in the presence of UV light, with the presence of oxygen accelerating the photodegradation. N1-acetyl-N2-formyl-5-methoxykynurenamine(AFMK) and 6-OHM were identified as the major photoproducts formed and these agents have been shown previously to retain antioxidant activity. One of the concerns of using melatonin in sunscreens is its photostability. However, it is reported in this study that the degraded solution of melatonin still possesses equipotent free radical scavenging ability as melatonin, despite the absence of melatonin in solution. In addition, melatonin is shown to reduce UV-induced oxidative stress in rat skin homogenate. Thus, these results make melatonin a likely candidate for inclusion in sunscreen preparations. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. 6-OHM is not only formed as the major hepatic metabolite of melatonin, but also when melatonin reacts with toxic radicals as well as UV light. Thus the second part of the study aims to elucidate and further characterize the mechanism behind 6-OHM’s neuroprotection. The results show 6-OHM to be a more potent singlet oxygen and superoxide anion scavenger than melatonin. In addition, the results show 6-OHM to offer protection against, oxidative stress and lipid peroxidation induced by several neurotoxins in the rat brain and hippocampus. The hippocampus is an important region of the brain responsible for the formation of memory and any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include quinolinic acid (QA) and iron (II). Histological studies undertaken reveal that 6-OHM is able to protect hippocampal neurons against QA and iron (II) induced necrotic cell death. Immunohistochemical investigations showed that QA moderately induces apoptotic cell death in the hippocampus which is inhibited by both melatonin and 6-OHM. The study sought to elucidate possible mechanisms by which 6-OHM exerts its neuroprotective capabilities and the results show 6-OHM to inhibit the action of cyanide on the mitochondrial electron transport chain (ETC), one of the most common sources of free radicals. In addition, 6-OHM treatment alone, increased ETC activity above basal control levels and the results show 6-OHM to increase complex I activity in the mitochondrial ETC. Electrochemical, ultraviolet/visible spectroscopy (UV/Vis) and HPLC assessment show that an interaction exists between 6-OHM and iron (III) and 6-OHM is able to reduce iron (III) to a more biologically usable form viz. iron (II) which can be incorporated into important biomolecules such as heme. One dire consequence of this interaction is the ready provision of iron (II) to drive the Fenton reaction. However the biological and histological assessments show 6-OHM to prevent iron (II)-induced lipid peroxidation and necrotic cell death and thus, provide evidence of its antioxidant properties. The results also show 6-OHM to promote Hsp70 induction in the hippocampus. Heat shock proteins, especially Hsp 70 plays a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. 6-OHM treatment alone and together with QA was shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that 6-OHM helps to protect against cellular protein damage induced by any form of stress the cell may encounter. Melatonin treatment alone and in combination with QA was shown to prevent increases in the level of Hsp70 in the hippocampus, indicating that melatonin was able to reduce oxidative stress induced by QA such that Hsp70 expression was not required. The discovery of neuroprotective agents, such as melatonin and 6-OHM, is becoming important considering the rapid rise in the elderly population and the proportionate increase in neurological disorders. The findings of this study indicate the need for important information regarding the correct storage conditions and stability characteristics of melatonin dosage forms. In addition, the results indicate that 6-OHM has a definite role to play as an antioxidant. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders.
- Full Text:
- Date Issued: 2003
- Authors: Maharaj, Deepa Sukhdev
- Date: 2003
- Subjects: Melatonin Nervous system -- Degeneration -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3768 , http://hdl.handle.net/10962/d1003246
- Description: Until the beginning of this decade the antioxidant, melatonin, had been considered as little more than a tranquilizing hormone, responsible for regulating certain circadian and circannual rhythms. However, it is the discovery of melatonin as a free radical scavenger that has generated the most interest in recent years. The reduction of melatonin with age has been associated with neurodegenerative diseases such as Alzheimer’s disease (AD)and therefore, melatonin has been implicated to have an important clinical role in neuroprotection. Thus, for several years melatonin has attracted increasing attention from the general press with many advertisements touting this indoleamine to act as an aphrodisiac, rejuvenator, protector against diseases and a general wonder drug. However, melatonin formulations appear with no labelling for the correct storage conditions, dosage and side effects, as well as no control for purity and self-medicating with an unregulated product. In addition, there is much controversy surrounding the antioxidative properties of the indolemaine, 6-hydroxymelatonin (6-OHM). Therefore, the first part of this study aims to elucidate the physico-chemical and various stability characteristics of the pineal antioxidant, melatonin, while the second part is devoted to investigating the neuroprotective properties of the primary hepatic metabolite of melatonin, 6-OHM. The physical properties of melatonin were determined using various chemical techniques. This information served to both characterize and confirm the identity of melatonin raw material used in this study. In addition, this information serves to be essential as the physical properties of melatonin have not been reported in detail in literature, to date. Thereafter, using a validated high performance liquid chromatography (HPLC) method, the various physico-chemical and stability characteristics of melatonin were determined. Melatonin was shown to be extremely lipophilic, while the hygroscopic study indicates that melatonin raw material is extremely hygroscopic at temperatures above 40°C, whereas melatonin tablets are hygroscopic when left out of the original container. This study highlights the need for consumers to be aware of the proper storage of melatonin tablets to improve the stability and ensure long term integrity of the compound. Since, melatonin is most often administered orally, thus exposing it to a large variations in pH, within the gastrointestinal tract, it was decided to investigate the stability of melatonin over a range of pH’s and temperatures. The findings imply that melatonin is relatively stable at body temperature when ingested orally and that orally administered slow release preparations of melatonin should be relatively stable and therefore exhibit favourable bioavailability. However melatonin was shown to be unstable in solution. This provides important information and a challenge to the formulators of this drug substance in a liquid dosage form. An assessment of the photostability of melatonin dosage forms using International Committee on Harmonization (ICH) conditions revealed melatonin to be light sensitive and thus indicates a need for careful consideration of the packaging of these drug products. In addition a detailed assessment of the photochemistry and photoproducts formed during the UV photodegradation of melatonin is reported. Melatonin is shown to rapidly degrade in the presence of UV light, with the presence of oxygen accelerating the photodegradation. N1-acetyl-N2-formyl-5-methoxykynurenamine(AFMK) and 6-OHM were identified as the major photoproducts formed and these agents have been shown previously to retain antioxidant activity. One of the concerns of using melatonin in sunscreens is its photostability. However, it is reported in this study that the degraded solution of melatonin still possesses equipotent free radical scavenging ability as melatonin, despite the absence of melatonin in solution. In addition, melatonin is shown to reduce UV-induced oxidative stress in rat skin homogenate. Thus, these results make melatonin a likely candidate for inclusion in sunscreen preparations. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. 6-OHM is not only formed as the major hepatic metabolite of melatonin, but also when melatonin reacts with toxic radicals as well as UV light. Thus the second part of the study aims to elucidate and further characterize the mechanism behind 6-OHM’s neuroprotection. The results show 6-OHM to be a more potent singlet oxygen and superoxide anion scavenger than melatonin. In addition, the results show 6-OHM to offer protection against, oxidative stress and lipid peroxidation induced by several neurotoxins in the rat brain and hippocampus. The hippocampus is an important region of the brain responsible for the formation of memory and any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include quinolinic acid (QA) and iron (II). Histological studies undertaken reveal that 6-OHM is able to protect hippocampal neurons against QA and iron (II) induced necrotic cell death. Immunohistochemical investigations showed that QA moderately induces apoptotic cell death in the hippocampus which is inhibited by both melatonin and 6-OHM. The study sought to elucidate possible mechanisms by which 6-OHM exerts its neuroprotective capabilities and the results show 6-OHM to inhibit the action of cyanide on the mitochondrial electron transport chain (ETC), one of the most common sources of free radicals. In addition, 6-OHM treatment alone, increased ETC activity above basal control levels and the results show 6-OHM to increase complex I activity in the mitochondrial ETC. Electrochemical, ultraviolet/visible spectroscopy (UV/Vis) and HPLC assessment show that an interaction exists between 6-OHM and iron (III) and 6-OHM is able to reduce iron (III) to a more biologically usable form viz. iron (II) which can be incorporated into important biomolecules such as heme. One dire consequence of this interaction is the ready provision of iron (II) to drive the Fenton reaction. However the biological and histological assessments show 6-OHM to prevent iron (II)-induced lipid peroxidation and necrotic cell death and thus, provide evidence of its antioxidant properties. The results also show 6-OHM to promote Hsp70 induction in the hippocampus. Heat shock proteins, especially Hsp 70 plays a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. 6-OHM treatment alone and together with QA was shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that 6-OHM helps to protect against cellular protein damage induced by any form of stress the cell may encounter. Melatonin treatment alone and in combination with QA was shown to prevent increases in the level of Hsp70 in the hippocampus, indicating that melatonin was able to reduce oxidative stress induced by QA such that Hsp70 expression was not required. The discovery of neuroprotective agents, such as melatonin and 6-OHM, is becoming important considering the rapid rise in the elderly population and the proportionate increase in neurological disorders. The findings of this study indicate the need for important information regarding the correct storage conditions and stability characteristics of melatonin dosage forms. In addition, the results indicate that 6-OHM has a definite role to play as an antioxidant. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders.
- Full Text:
- Date Issued: 2003
An investigation into the relationship marketing strategies applied by Eastern Cape based travel agents
- Authors: Fisher, Gary
- Date: 2003
- Subjects: Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech (Marketing)
- Identifier: vital:10766 , http://hdl.handle.net/10948/251 , Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Description: Relationship marketing has grown in importance. This growth affects all industries, including the tourism, hospitality and travel industry. Of particular importance is the bond of relationship marketing between suppliers (principals) and retailers (travel agents) in the distribution channel. The research was undertaken to: determine whether Eastern Cape travel agents perceive relationship marketing as important; establish, what the key elements of relationship marketing strategies are,according to literature; determine what marketing strategies are currently applied by Eastern Cape travel agents; provide guidelines to Eastern Cape travel agents to implement or improve their relationship marketing strategies. Fifty self-administered questionnaires were distributed to the entire population of travel agents in the Eastern Cape. A total of 30 travel agents responded. The empirical findings showed that: Most Eastern Cape travel agents perceived relationship marketing as important; Travel agents realized the importance of the management of such relationship marketing strategies; Most travel agents were aware of or used retention strategies to enhance relationship marketing strategies; Travel agents realized that to survive relationship marketing should be part of their future planning; All respondents believed that to successfully implement relationship marketing, all staff, from front-line to top-management, need to be committed to the programme. In conclusion, relationship marketing is growing in importance and all role players need to acknowledge and manage this trend. However, this research has shown that there is a paradigm shift as more travel agents are moving away from the traditional marketing to relationship marketing.
- Full Text:
- Date Issued: 2003
- Authors: Fisher, Gary
- Date: 2003
- Subjects: Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech (Marketing)
- Identifier: vital:10766 , http://hdl.handle.net/10948/251 , Relationship marketing -- South Africa -- Eastern Cape , Travel agents -- South Africa -- Eastern Cape
- Description: Relationship marketing has grown in importance. This growth affects all industries, including the tourism, hospitality and travel industry. Of particular importance is the bond of relationship marketing between suppliers (principals) and retailers (travel agents) in the distribution channel. The research was undertaken to: determine whether Eastern Cape travel agents perceive relationship marketing as important; establish, what the key elements of relationship marketing strategies are,according to literature; determine what marketing strategies are currently applied by Eastern Cape travel agents; provide guidelines to Eastern Cape travel agents to implement or improve their relationship marketing strategies. Fifty self-administered questionnaires were distributed to the entire population of travel agents in the Eastern Cape. A total of 30 travel agents responded. The empirical findings showed that: Most Eastern Cape travel agents perceived relationship marketing as important; Travel agents realized the importance of the management of such relationship marketing strategies; Most travel agents were aware of or used retention strategies to enhance relationship marketing strategies; Travel agents realized that to survive relationship marketing should be part of their future planning; All respondents believed that to successfully implement relationship marketing, all staff, from front-line to top-management, need to be committed to the programme. In conclusion, relationship marketing is growing in importance and all role players need to acknowledge and manage this trend. However, this research has shown that there is a paradigm shift as more travel agents are moving away from the traditional marketing to relationship marketing.
- Full Text:
- Date Issued: 2003
An investigation into whether a leadership and management development project changed the perceptions of the educators in a black, disadvantaged school
- Authors: Jaftha, A P
- Date: 2003
- Subjects: University of Port Elizabeth -- Institute for Development Planning and Research Delta Foundation -- Centres of Learning School management and organization -- South Africa Educational leadership -- South Africa Educational change -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1620 , http://hdl.handle.net/10962/d1003502
- Description: This study investigates whether a leadership and management development programme changed the management perceptions of the teachers of one of the schools that participated in the programme. The programme seeks to change the organisational culture of schools and develop effective management. The development philosophy of the programme is informed by literature on school effectiveness, organisation development, whole school development and systemic change. My research is conducted in the interpretive paradigm. Interpretive researchers view reality a construct of the human mind, and therefore the way people perceive the world is not necessarily the same since there can be different understandings of what is real. I employ convenience sampling to select the school and purposive sampling to identify my research participants. Whilst overall impression that the data conveys is that much of the programme does not seem to have had a lasting effect on the culture of the school, it nonetheless made an impression on the teachers’ perceptions of management. There clearly seems to be a greater appreciation of participative management processes. The reintroduction of proper prior planning played a decisive role in re-establishing sound work ethics at the school and contributes to a more structured approach to events at the school. Some sort of organisational learning has also been introduced at the school. The realisation on the part of the staff that they now have their destiny in their own hands is an especially critical development. And whilst the vision is not a compelling force in the organisation, it has nevertheless produced some strategic focus at the school. The insights and skills they acquired concerning resource management will also stand them in good stead.
- Full Text:
- Date Issued: 2003
- Authors: Jaftha, A P
- Date: 2003
- Subjects: University of Port Elizabeth -- Institute for Development Planning and Research Delta Foundation -- Centres of Learning School management and organization -- South Africa Educational leadership -- South Africa Educational change -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1620 , http://hdl.handle.net/10962/d1003502
- Description: This study investigates whether a leadership and management development programme changed the management perceptions of the teachers of one of the schools that participated in the programme. The programme seeks to change the organisational culture of schools and develop effective management. The development philosophy of the programme is informed by literature on school effectiveness, organisation development, whole school development and systemic change. My research is conducted in the interpretive paradigm. Interpretive researchers view reality a construct of the human mind, and therefore the way people perceive the world is not necessarily the same since there can be different understandings of what is real. I employ convenience sampling to select the school and purposive sampling to identify my research participants. Whilst overall impression that the data conveys is that much of the programme does not seem to have had a lasting effect on the culture of the school, it nonetheless made an impression on the teachers’ perceptions of management. There clearly seems to be a greater appreciation of participative management processes. The reintroduction of proper prior planning played a decisive role in re-establishing sound work ethics at the school and contributes to a more structured approach to events at the school. Some sort of organisational learning has also been introduced at the school. The realisation on the part of the staff that they now have their destiny in their own hands is an especially critical development. And whilst the vision is not a compelling force in the organisation, it has nevertheless produced some strategic focus at the school. The insights and skills they acquired concerning resource management will also stand them in good stead.
- Full Text:
- Date Issued: 2003
An investigation of code switching in different learning areas in a grade seven class
- Authors: Ndabeni, Bulelwa
- Date: 2003
- Subjects: Code switching (Linguistics) -- South Africa Language and education -- South Africa Education, Bilingual -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1621 , http://hdl.handle.net/10962/d1003503
- Description: The research described in this thesis is a case study of the communicative repertoires of teachers and learners of a grade seven class in a small rural primary school. The aim of the investigation was to find out if code switching is different in content-subject classes than in an English language class. The study accomplishes this by looking at code switching in different learning areas. Different research techniques such as observations, video. recording, taking of field notes and interviews are used as the means of data collection. The study does not attempt a full linguistic description of the switches made by the research subjects. For example, it does not deal with linguistic constraints on code switching, but instead it focuses on the functional aspects of code switching. The study reveals that there are various functions of code switching in the classroom. The following are the major findings noted in this study: • Code switching is a communicative resource, which enables the teachers and learners to accomplish a considerable number and range of social and educational objectives. • Code switching is used to negotiate and renegotiate meaning. • How teachers code switch in class depends on how difficult the lesson is for the learners. • The study reveals no major differences between code switching In content subjects than in English as a subject. • Although tbe subjects engage in code switching, they seem to feel guilty about their behaviour.
- Full Text:
- Date Issued: 2003
- Authors: Ndabeni, Bulelwa
- Date: 2003
- Subjects: Code switching (Linguistics) -- South Africa Language and education -- South Africa Education, Bilingual -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1621 , http://hdl.handle.net/10962/d1003503
- Description: The research described in this thesis is a case study of the communicative repertoires of teachers and learners of a grade seven class in a small rural primary school. The aim of the investigation was to find out if code switching is different in content-subject classes than in an English language class. The study accomplishes this by looking at code switching in different learning areas. Different research techniques such as observations, video. recording, taking of field notes and interviews are used as the means of data collection. The study does not attempt a full linguistic description of the switches made by the research subjects. For example, it does not deal with linguistic constraints on code switching, but instead it focuses on the functional aspects of code switching. The study reveals that there are various functions of code switching in the classroom. The following are the major findings noted in this study: • Code switching is a communicative resource, which enables the teachers and learners to accomplish a considerable number and range of social and educational objectives. • Code switching is used to negotiate and renegotiate meaning. • How teachers code switch in class depends on how difficult the lesson is for the learners. • The study reveals no major differences between code switching In content subjects than in English as a subject. • Although tbe subjects engage in code switching, they seem to feel guilty about their behaviour.
- Full Text:
- Date Issued: 2003