"Effulgent in the firmament" the politics of representation and the politics of reception in South Africa's 'poetry of commitment', 1968-1983
- Authors: Mde, Vukani
- Date: 2002
- Subjects: South African literature -- Black authors -- History and criticism , Politics and literature -- South Africa -- History -- 20th century , Literature and state -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10987 , http://hdl.handle.net/10948/288 , South African literature -- Black authors -- History and criticism , Politics and literature -- South Africa -- History -- 20th century , Literature and state -- South Africa
- Description: This dissertation re-examines an era in the production and reception of English language poetry in South Africa by black writers. Intellectually the 1970's was the Black Consciousness phase of South African history and very few aspects of life in the country were untouched by the intellectual movement led by Steve Biko and other young black student leaders. The aesthetic and literary output of the time, like all other facets of South African life, exhibited the influence and pressures brought to bear by Black Consciousness. Moreover, the Black Consciousness poets introduced the most vibrant and innovative phase for English language poetry produced in South Africa. It is my contention, however, that such vibrancy and innovation has consistently been compromised by unsympathetic, often hostile, and almost-always ill-informed criticism. The dissertation offers a critique of the academic and journalistic practice of criticism in South Africa. I argue that critical practice in South Africa has been engaged throughout the twentieth century in the discursive enforcement of ‘discipline’. In his Discipline and Punish (1977) the French post-structuralist philosopher Michel Foucault demonstrated how power is wielded against oppressed/suppressed groups through self regulated proscriptions, and argued that power is a discursive rather than a corporeal phenomenon. My dissertation follows Foucault in reading the critical reception of Black Consciousness poetry as the practice of disciplinary power. The dissertation also engages critically with the poetry of Oswald Mtshali, Mongane Serote and Sipho Sepamla, and argues that their work is the inscription of black subjectivity into the literary and cultural mainstream. It situates their work within wider 6 societal debates and definitions of ‘blackness’. In this regard use is made again of Michel Foucault’s insights and methodology of discourse analysis as shown in The Archaeology of Knowledge (1972). I argue that Oswald Mtshali’s work is a failed attempt at a dissection of apartheid and colonialism from a broadly Christian and humanist perspective. In my reading of Mongane Serote I explore the relationship between women’s bodies and the practice of representation. It is my contention that Serote is most concerned with claims of belonging, and this is shown through his extensive use of the trope of ‘Mother’. My discussion of the poetry of Sipho Sepamla focuses on language and (self- )representation, particularly the use of practices of naming in constructing subjectivity. My contention is that Sepamla ultimately abandons attempts at representation in favour of oppositional self-construction in language. In the concluding chapter I defend the thesis that the politics of discipline have prevented the broad critical establishment from gaining access to these discursive constructions of blackness in the committed poetry of South Africa.
- Full Text:
- Date Issued: 2002
- Authors: Mde, Vukani
- Date: 2002
- Subjects: South African literature -- Black authors -- History and criticism , Politics and literature -- South Africa -- History -- 20th century , Literature and state -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10987 , http://hdl.handle.net/10948/288 , South African literature -- Black authors -- History and criticism , Politics and literature -- South Africa -- History -- 20th century , Literature and state -- South Africa
- Description: This dissertation re-examines an era in the production and reception of English language poetry in South Africa by black writers. Intellectually the 1970's was the Black Consciousness phase of South African history and very few aspects of life in the country were untouched by the intellectual movement led by Steve Biko and other young black student leaders. The aesthetic and literary output of the time, like all other facets of South African life, exhibited the influence and pressures brought to bear by Black Consciousness. Moreover, the Black Consciousness poets introduced the most vibrant and innovative phase for English language poetry produced in South Africa. It is my contention, however, that such vibrancy and innovation has consistently been compromised by unsympathetic, often hostile, and almost-always ill-informed criticism. The dissertation offers a critique of the academic and journalistic practice of criticism in South Africa. I argue that critical practice in South Africa has been engaged throughout the twentieth century in the discursive enforcement of ‘discipline’. In his Discipline and Punish (1977) the French post-structuralist philosopher Michel Foucault demonstrated how power is wielded against oppressed/suppressed groups through self regulated proscriptions, and argued that power is a discursive rather than a corporeal phenomenon. My dissertation follows Foucault in reading the critical reception of Black Consciousness poetry as the practice of disciplinary power. The dissertation also engages critically with the poetry of Oswald Mtshali, Mongane Serote and Sipho Sepamla, and argues that their work is the inscription of black subjectivity into the literary and cultural mainstream. It situates their work within wider 6 societal debates and definitions of ‘blackness’. In this regard use is made again of Michel Foucault’s insights and methodology of discourse analysis as shown in The Archaeology of Knowledge (1972). I argue that Oswald Mtshali’s work is a failed attempt at a dissection of apartheid and colonialism from a broadly Christian and humanist perspective. In my reading of Mongane Serote I explore the relationship between women’s bodies and the practice of representation. It is my contention that Serote is most concerned with claims of belonging, and this is shown through his extensive use of the trope of ‘Mother’. My discussion of the poetry of Sipho Sepamla focuses on language and (self- )representation, particularly the use of practices of naming in constructing subjectivity. My contention is that Sepamla ultimately abandons attempts at representation in favour of oppositional self-construction in language. In the concluding chapter I defend the thesis that the politics of discipline have prevented the broad critical establishment from gaining access to these discursive constructions of blackness in the committed poetry of South Africa.
- Full Text:
- Date Issued: 2002
A preliminary investigation into the patterns of performance on a computerized adaptive test battery implications for admissions and placement
- Authors: Vorster, Marlene
- Date: 2002
- Subjects: Universities and colleges -- Admission , Advanced placement programs (Education) , Computer adaptive testing , Universities and colleges -- Entrance requirements
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:11030 , http://hdl.handle.net/10948/285 , Universities and colleges -- Admission , Advanced placement programs (Education) , Computer adaptive testing , Universities and colleges -- Entrance requirements
- Description: The fallibility of human judgment in the making of decisions requires the use of tests to enhance decision-making processes. Although testing is surrounded with issues of bias and fairness, it remains the best means of facilitating decisions over more subjective alternatives. As a country in transition, all facets of South African society are being transformed. The changes taking place within the tertiary education system to redress the legacy of Apartheid, coincide with an international trend of transforming higher education. One important area that is being transformed relates to university entrance requirements and admissions procedures. In South Africa, these were traditionally based on matriculation performance, which has been found to be a more variable predictor of academic success for historically disadvantaged students. Alternative or revised admissions procedures have been implemented at universities throughout the country, in conjunction with academic development programmes. However, it is argued in this dissertation that a paradigm shift is necessary to conceptualise admissions and placement assessment in a developmentally oriented way. Furthermore, it is motivated that it is important to keep abreast of advances in theory, such as item response theory (IRT) and technology, such as computerized adaptive testing (CAT), in test development to enhance the effectiveness of selecting and placing learners in tertiary programmes. This study focuses on investigating the use of the Accuplacer Computerized Placement Tests (CPTs), an adaptive test battery that was developed in the USA, to facilitate unbiased and fair admissions, placement and development decisions in the transforming South African context. The battery has been implemented at a university in the Eastern Cape and its usefulness was investigated for 193 participants, divided into two groups of degree programmes, depending on whether or not admission to the degree required mathematics as a matriculation subject. Mathematics based degree programme learners (n = 125) wrote three and non-mathematics based degree programme learners (n = 68) wrote two tests of the Accuplacer test battery. Correlations were computed between the Accuplacer scores and matriculation performance, and between the Accuplacer scores, matriculation performance and academic results. All yielded significant positive relationships excepting for the one subtest of the Accuplacer with academic performance for the non-mathematics based degree group. Multiple correlations for both groups indicated that the Accuplacer scores and matriculation results contribute unique information about academic performance. Cluster analysis for both groups yielded three underlying patterns of performance in the data sets. An attempt was made to validate the cluster groups internally through a MANOVA and single-factor ANOVAs. It was found that Accuplacer subtests and matriculation results do discriminate to an extent among clusters of learners in both groups of degree programmes investigated. Clusters were described in terms of demographic information and it was determined that the factors of culture and home language and how they relate to cluster group membership need further investigation. The main suggestion flowing from these findings is that an attempt be made to confirm the results with a larger sample size and for different cultural and language groups.
- Full Text:
- Date Issued: 2002
- Authors: Vorster, Marlene
- Date: 2002
- Subjects: Universities and colleges -- Admission , Advanced placement programs (Education) , Computer adaptive testing , Universities and colleges -- Entrance requirements
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:11030 , http://hdl.handle.net/10948/285 , Universities and colleges -- Admission , Advanced placement programs (Education) , Computer adaptive testing , Universities and colleges -- Entrance requirements
- Description: The fallibility of human judgment in the making of decisions requires the use of tests to enhance decision-making processes. Although testing is surrounded with issues of bias and fairness, it remains the best means of facilitating decisions over more subjective alternatives. As a country in transition, all facets of South African society are being transformed. The changes taking place within the tertiary education system to redress the legacy of Apartheid, coincide with an international trend of transforming higher education. One important area that is being transformed relates to university entrance requirements and admissions procedures. In South Africa, these were traditionally based on matriculation performance, which has been found to be a more variable predictor of academic success for historically disadvantaged students. Alternative or revised admissions procedures have been implemented at universities throughout the country, in conjunction with academic development programmes. However, it is argued in this dissertation that a paradigm shift is necessary to conceptualise admissions and placement assessment in a developmentally oriented way. Furthermore, it is motivated that it is important to keep abreast of advances in theory, such as item response theory (IRT) and technology, such as computerized adaptive testing (CAT), in test development to enhance the effectiveness of selecting and placing learners in tertiary programmes. This study focuses on investigating the use of the Accuplacer Computerized Placement Tests (CPTs), an adaptive test battery that was developed in the USA, to facilitate unbiased and fair admissions, placement and development decisions in the transforming South African context. The battery has been implemented at a university in the Eastern Cape and its usefulness was investigated for 193 participants, divided into two groups of degree programmes, depending on whether or not admission to the degree required mathematics as a matriculation subject. Mathematics based degree programme learners (n = 125) wrote three and non-mathematics based degree programme learners (n = 68) wrote two tests of the Accuplacer test battery. Correlations were computed between the Accuplacer scores and matriculation performance, and between the Accuplacer scores, matriculation performance and academic results. All yielded significant positive relationships excepting for the one subtest of the Accuplacer with academic performance for the non-mathematics based degree group. Multiple correlations for both groups indicated that the Accuplacer scores and matriculation results contribute unique information about academic performance. Cluster analysis for both groups yielded three underlying patterns of performance in the data sets. An attempt was made to validate the cluster groups internally through a MANOVA and single-factor ANOVAs. It was found that Accuplacer subtests and matriculation results do discriminate to an extent among clusters of learners in both groups of degree programmes investigated. Clusters were described in terms of demographic information and it was determined that the factors of culture and home language and how they relate to cluster group membership need further investigation. The main suggestion flowing from these findings is that an attempt be made to confirm the results with a larger sample size and for different cultural and language groups.
- Full Text:
- Date Issued: 2002
The concurrent jurisdiction of the Labour Court and the High Court
- Authors: Wagener, Pieter Cornelius
- Date: 2002
- Subjects: South Africa. High Court , South Africa. Labour Court , Exclusive and concurrent legislative powers -- South Africa , Law, Interpretation and construction
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11051 , http://hdl.handle.net/10948/286 , South Africa. High Court , South Africa. Labour Court , Exclusive and concurrent legislative powers -- South Africa , Law, Interpretation and construction
- Description: An overview is given of the difficulties surrounding the concurrent jurisdiction of the Labour Court and High Court The main categories of the jurisdictional dispute are identified and systemised. The main branches are those of statutory overlap and interpretation of statutes. Statutory overlap concerns matters remaining from the industrial court era, urgent applications, delict and law of contract. Statutory interpretation mainly involves the interpretation of provisions in the Bill of Rights of the Constitution. An overview of the principles of jurisdiction with respect to the different courts, as well as a brief historical review of the development of such jurisdiction is given. Particular attention is given to the role of fundamental rights in the Constitution. Broad principles are identified whereby the difficulties may be addressed.
- Full Text:
- Date Issued: 2002
- Authors: Wagener, Pieter Cornelius
- Date: 2002
- Subjects: South Africa. High Court , South Africa. Labour Court , Exclusive and concurrent legislative powers -- South Africa , Law, Interpretation and construction
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11051 , http://hdl.handle.net/10948/286 , South Africa. High Court , South Africa. Labour Court , Exclusive and concurrent legislative powers -- South Africa , Law, Interpretation and construction
- Description: An overview is given of the difficulties surrounding the concurrent jurisdiction of the Labour Court and High Court The main categories of the jurisdictional dispute are identified and systemised. The main branches are those of statutory overlap and interpretation of statutes. Statutory overlap concerns matters remaining from the industrial court era, urgent applications, delict and law of contract. Statutory interpretation mainly involves the interpretation of provisions in the Bill of Rights of the Constitution. An overview of the principles of jurisdiction with respect to the different courts, as well as a brief historical review of the development of such jurisdiction is given. Particular attention is given to the role of fundamental rights in the Constitution. Broad principles are identified whereby the difficulties may be addressed.
- Full Text:
- Date Issued: 2002
The effect of nutrient levels and ratios on the growth of Microcystis aeruginosa and microcystin production
- Authors: Sember, Craig Stewart
- Date: 2002
- Subjects: Microcystis aeruginosa -- Toxicology , Nitrates , Microcystins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11076 , http://hdl.handle.net/10948/287 , Microcystis aeruginosa -- Toxicology , Nitrates , Microcystins
- Description: This study reports the findings on the effect of nitrates and phosphates on the biomass and toxin production of various strains of the unicellular non-nitrogen fixing cyanobacterium, Microcystis aeruginosa. The occurrence of blooms of Microcystis aeruginosa and microcystin in freshwater impoundments across the globe has been on the increase lately due to increased levels of eutrophication, resulting in human and animal deaths and illness, as well as drinking and recreational water foulment. A range of environmental factors have been shown to effect growth and microcystin production. Existing literature however is somewhat contradictory as to the effects of these physical and chemical factors on toxin production. Therefore Microcystis aeruginosa strains were cultured under batch and continuous conditions to determine the effect of nitrate and phosphate concentrations and ratios on biomass and toxin production. Cultures were analysed with regards to internal nutrient stores, biomass production, nutrient depletion, photosynthetic efficiency and microcystin production. Results showed that microcystin production correlated to growth rate, photosynthetic efficiency and internal nitrogen stores and that an optimal N:P ratio was associated with microcystin levels, growth rate and photosynthetic efficiency. Results therefore led to the conclusion that the nitrogen, carbon, and phosphate balance within the cell is closely associated with microcystin production. Whether or not microcystin is produced to maintain this balance or produced as a function of this balance remains to be determined.
- Full Text:
- Date Issued: 2002
- Authors: Sember, Craig Stewart
- Date: 2002
- Subjects: Microcystis aeruginosa -- Toxicology , Nitrates , Microcystins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11076 , http://hdl.handle.net/10948/287 , Microcystis aeruginosa -- Toxicology , Nitrates , Microcystins
- Description: This study reports the findings on the effect of nitrates and phosphates on the biomass and toxin production of various strains of the unicellular non-nitrogen fixing cyanobacterium, Microcystis aeruginosa. The occurrence of blooms of Microcystis aeruginosa and microcystin in freshwater impoundments across the globe has been on the increase lately due to increased levels of eutrophication, resulting in human and animal deaths and illness, as well as drinking and recreational water foulment. A range of environmental factors have been shown to effect growth and microcystin production. Existing literature however is somewhat contradictory as to the effects of these physical and chemical factors on toxin production. Therefore Microcystis aeruginosa strains were cultured under batch and continuous conditions to determine the effect of nitrate and phosphate concentrations and ratios on biomass and toxin production. Cultures were analysed with regards to internal nutrient stores, biomass production, nutrient depletion, photosynthetic efficiency and microcystin production. Results showed that microcystin production correlated to growth rate, photosynthetic efficiency and internal nitrogen stores and that an optimal N:P ratio was associated with microcystin levels, growth rate and photosynthetic efficiency. Results therefore led to the conclusion that the nitrogen, carbon, and phosphate balance within the cell is closely associated with microcystin production. Whether or not microcystin is produced to maintain this balance or produced as a function of this balance remains to be determined.
- Full Text:
- Date Issued: 2002
The effect of selenium in the detoxification of the microcystin hepatotoxins
- Authors: Downs, Kerry
- Date: 2002
- Subjects: Cynaobacterial toxins , Microcystins , Selenium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11070 , http://hdl.handle.net/10948/284 , Cynaobacterial toxins , Microcystins , Selenium
- Description: Blooms of cyanobacteria have been known to cause illness in humans and death in wild and domestic animals. One of the toxins produced by cyanobacteria is microcystin, which is a potent hepatotoxin. Microcystin is taken up by bile acid transporters in the intestine and transported into the liver. After exposure to acute doses of microcystin, severe haemorrhage has been observed along with apoptotic and necrotic hepatocytes. The cytoskeletal structure of the hepatocytes is disrupted and oxidative stress is induced. Selenium, a known anti-oxidant, has been shown to induce increased activity of glutathione peroxidase. Glutathione peroxidase removes peroxides from cells protecting them from oxidative stress. This study set out to determine if selenium could play a role in preventing the damage to mice livers due to microcystin toxin. The protective role of selenium was explored in three main studies: in the first study, the ability of selenium to increase the survival time of mice exposed to a lethal dose of toxin was determined. In the second study the mice were exposed to sublethal chronic doses of toxin over 30 days. The ability of selenium to minimise liver damage under these conditions was determined. The final study investigated the mechanism of the protective effect of selenium. The results of the first study suggested that selenium could extend survival time. In the second study the selenium supplemented mice showed a reduction in the extent of the increase in liver weight and a decrease in the amount of lipid peroxidation induced compared to the mice that received only toxin. The histology of the selenium supplemented mice also showed a decrease in the severity and amount of morphological changes in the liver. The third study indicated that the protection shown by selenium might be mediated by an increase in the glutathione peroxidase (GPX) activity in selenium supplemented mice. This increase in GPX activity would increase the removal of the lipid hydroperoxides and prevent the damage they would cause in the cell. A further result indicated an increase in glutathione S-transferase in only the toxin control mice when compared to the selenium supplemented and control mice. ii In conclusion selenium offers protection against microcystin but further studies need to be done to provide statistically valid results to clarify the level of protection.
- Full Text:
- Date Issued: 2002
- Authors: Downs, Kerry
- Date: 2002
- Subjects: Cynaobacterial toxins , Microcystins , Selenium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11070 , http://hdl.handle.net/10948/284 , Cynaobacterial toxins , Microcystins , Selenium
- Description: Blooms of cyanobacteria have been known to cause illness in humans and death in wild and domestic animals. One of the toxins produced by cyanobacteria is microcystin, which is a potent hepatotoxin. Microcystin is taken up by bile acid transporters in the intestine and transported into the liver. After exposure to acute doses of microcystin, severe haemorrhage has been observed along with apoptotic and necrotic hepatocytes. The cytoskeletal structure of the hepatocytes is disrupted and oxidative stress is induced. Selenium, a known anti-oxidant, has been shown to induce increased activity of glutathione peroxidase. Glutathione peroxidase removes peroxides from cells protecting them from oxidative stress. This study set out to determine if selenium could play a role in preventing the damage to mice livers due to microcystin toxin. The protective role of selenium was explored in three main studies: in the first study, the ability of selenium to increase the survival time of mice exposed to a lethal dose of toxin was determined. In the second study the mice were exposed to sublethal chronic doses of toxin over 30 days. The ability of selenium to minimise liver damage under these conditions was determined. The final study investigated the mechanism of the protective effect of selenium. The results of the first study suggested that selenium could extend survival time. In the second study the selenium supplemented mice showed a reduction in the extent of the increase in liver weight and a decrease in the amount of lipid peroxidation induced compared to the mice that received only toxin. The histology of the selenium supplemented mice also showed a decrease in the severity and amount of morphological changes in the liver. The third study indicated that the protection shown by selenium might be mediated by an increase in the glutathione peroxidase (GPX) activity in selenium supplemented mice. This increase in GPX activity would increase the removal of the lipid hydroperoxides and prevent the damage they would cause in the cell. A further result indicated an increase in glutathione S-transferase in only the toxin control mice when compared to the selenium supplemented and control mice. ii In conclusion selenium offers protection against microcystin but further studies need to be done to provide statistically valid results to clarify the level of protection.
- Full Text:
- Date Issued: 2002
The immobilization of Microcystis aeruginosa PCC7806 on a membrane nutrient-gradostat bioreacator for the production of the secondary metobolites
- Authors: Strong, Peter James
- Date: 2002
- Subjects: Microcystis aeruginosa , Myrocystins , Bioreactors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11083 , http://hdl.handle.net/10948/283 , Microcystis aeruginosa , Myrocystins , Bioreactors
- Description: A module and an inoculation technique were developed that would allow for the efficient immobilization of Microcystis aeruginosa PCC7806 on a synthetic membrane. A variety of module types, membranes (ceramic, tubular polyethersulfone and externally skinless polyethersulfone capillary membrane), and methods of immobilization (adsorption, pressure filtration and a developed technique that involved drying a cell slurry on a membrane) were assessed. The morphological properties that affected the immobilization of Microcystis aeruginosa PCC7806, as well as the effects of immobilization upon cell morphology were assessed. Cells in the stationary growth phase, which had a well-developed extra-cellular polysaccharide layer and no gas vesicles, were optimal for immobilization. Microcystin production under immobilized conditions was assessed under different nitrate concentrations, light intensities, biofilm thickness and immobilization times. Additional work included assaying for Microcystin production of two airlift-grown cultures under a high light intensity and complete nutrient deprivation and the inoculation of a ceramic membrane. An immunological technique was used to elucidate where toxin production was greatest within a biofilm immobilized upon an externally skinless polyethersulfone capillary membrane. The externally skinless polyethersulfone capillary membrane was evaluated to assess homogeneity and the physical differences between membrane batches that led to the erratic, incomplete biofilm formation, as a biofilm of a constant thickness could not be immobilized. Microcystis aeruginosa PCC7806 was exposed to a variety of solvents in order to permeabilize the cyanobacteria, as that would have enabled a truly continuous extraction process for the metabolite. FDA hydrolysis had to be optimized in order to use it as an indicator of cell viability. In addition a single-step extraction of Microcystin was attempted using live bacteria. A capillary membrane module, containing the externally skinless polyethersulfone capillary membrane, inoculated using pressure filtration, was the most efficient combination to establish a biofilm. Cells that were no longer actively dividing and that lacked buoyancy displayed superior immobilization to cells that were actively dividing and buoyant. The immobilized cells did produce Microcystin but in much lower concentrations to cells grown in an airlift culture. Biofilms grown with a higher nitrate concentration, a lower biofilm thickness and a lower light intensity had a higher specific microcystin content, while biofilms with a higher nitrate concentration a lower light intensity and a longer growth period displayed the a greater toxin production per mm2 of membrane. Microcystin occurred at its highest concentration in cells just above the pore opening. The diffusion of nutrients occurred relatively quickly to the outside layers of the biofilm, with a true gradient being established laterally from these nutrient veins that were above the pores. Permeabilization of the cells proved unsuccessful, as cells that remained viable did not release the intracellular compound into the surrounding medium.
- Full Text:
- Date Issued: 2002
- Authors: Strong, Peter James
- Date: 2002
- Subjects: Microcystis aeruginosa , Myrocystins , Bioreactors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11083 , http://hdl.handle.net/10948/283 , Microcystis aeruginosa , Myrocystins , Bioreactors
- Description: A module and an inoculation technique were developed that would allow for the efficient immobilization of Microcystis aeruginosa PCC7806 on a synthetic membrane. A variety of module types, membranes (ceramic, tubular polyethersulfone and externally skinless polyethersulfone capillary membrane), and methods of immobilization (adsorption, pressure filtration and a developed technique that involved drying a cell slurry on a membrane) were assessed. The morphological properties that affected the immobilization of Microcystis aeruginosa PCC7806, as well as the effects of immobilization upon cell morphology were assessed. Cells in the stationary growth phase, which had a well-developed extra-cellular polysaccharide layer and no gas vesicles, were optimal for immobilization. Microcystin production under immobilized conditions was assessed under different nitrate concentrations, light intensities, biofilm thickness and immobilization times. Additional work included assaying for Microcystin production of two airlift-grown cultures under a high light intensity and complete nutrient deprivation and the inoculation of a ceramic membrane. An immunological technique was used to elucidate where toxin production was greatest within a biofilm immobilized upon an externally skinless polyethersulfone capillary membrane. The externally skinless polyethersulfone capillary membrane was evaluated to assess homogeneity and the physical differences between membrane batches that led to the erratic, incomplete biofilm formation, as a biofilm of a constant thickness could not be immobilized. Microcystis aeruginosa PCC7806 was exposed to a variety of solvents in order to permeabilize the cyanobacteria, as that would have enabled a truly continuous extraction process for the metabolite. FDA hydrolysis had to be optimized in order to use it as an indicator of cell viability. In addition a single-step extraction of Microcystin was attempted using live bacteria. A capillary membrane module, containing the externally skinless polyethersulfone capillary membrane, inoculated using pressure filtration, was the most efficient combination to establish a biofilm. Cells that were no longer actively dividing and that lacked buoyancy displayed superior immobilization to cells that were actively dividing and buoyant. The immobilized cells did produce Microcystin but in much lower concentrations to cells grown in an airlift culture. Biofilms grown with a higher nitrate concentration, a lower biofilm thickness and a lower light intensity had a higher specific microcystin content, while biofilms with a higher nitrate concentration a lower light intensity and a longer growth period displayed the a greater toxin production per mm2 of membrane. Microcystin occurred at its highest concentration in cells just above the pore opening. The diffusion of nutrients occurred relatively quickly to the outside layers of the biofilm, with a true gradient being established laterally from these nutrient veins that were above the pores. Permeabilization of the cells proved unsuccessful, as cells that remained viable did not release the intracellular compound into the surrounding medium.
- Full Text:
- Date Issued: 2002
The medicinal chemistry of the isomers of the cyclic dipeptide: cyclo(Trp-Pro)
- Authors: Jamie, Hajierah
- Date: 2002
- Subjects: Pharmaceutical chemistry , Cyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11023 , http://hdl.handle.net/10948/281 , Pharmaceutical chemistry , Cyclic compounds
- Description: The isomers of cyclo(Trp-Pro) (cyclo(L-Trp-L-Pro), cyclo(L-Trp-D-Pro), cyclo(D-Trp-LPro) and cyclo(D-Trp-D-Pro)) have been successfully synthesized and screened for biological activity. High percentage yields were obtained by using the three phase synthesis system, which involves the synthesis of the intermediate protected linear dipeptides, followed by the removal of the protecting Boc groups. This step is followed by cyclization and crystallization of the isomers. The diketopiperazines rings of cyclo(L-Trp-L-Pro) and cyclo(D-Trp-D-Pro) contain cisamide bonds, while cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) contain trans-amide bonds. These bonds govern the conformation of the diketopiperazines ring. The isomers have shown different degrees of biological activity, possibly as a result of the orientation of the side chain of tryptophan and this difference in conformation, leading to varying interactions between isomer and a range of receptors. Under experimental conditions, 10-3 M cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) showed effective anticancer activity against the cervical cancer cell line, HeLa, resulting in a <50% reduction in cell viability. Cytotoxicity screening with cyclo(D-Trp-L-Pro) indicated that it was hepatocyte-specific in its toxicity, whilst the other isomers were cytotoxic against the other cell types tested. At 1mg/ml, cyclo(L-Trp-L-Pro) proved to be an effective antimicrobial agent against Gram positive bacteria, while cyclo(L-Trp-DPro) effectively inhibited the growth of the Gram negative bacteria, Esherichia coli. Cyclo(D-Trp-L-Pro) proved to be effective against Streptococcus, while cyclo(D-Trp-DPro) effectively reduced viability of the yeast, Candida albicans. Cyclo(D-Trp-L-Pro) was the only isomer to show Ca2+-channel antagonism, whilst the other isomers resulted in opening of the Ca2+-channel. No effects were observed on K+-channel activity for all the isomers tested. The isomers also proved to be valuable antiarrhythmic agents by effectively reducing the time spent in ventricular tachycardia and arrhythmia, as well as decreasing the time for the heart rate to return to a normal sinus rhythm. Furthermore, cyclo(L-Trp-D-Pro) showed positive chronotropic activity, while cyclo(D-Trp-L-Pro) ii showed negative chronotropic activity. In addition, cyclo(L-Trp-D-Pro) and cyclo(D-Trp- L-Pro) also increased the coronary flow rate. 0.125 1 mM Cyclo(L-Trp-D-Pro) decreased aggregation in washed platelets induced by thrombin. All isomers increased adhesion to an artificial surface when the platelets were stimulated by ADP, yet caused reduced adhesion when the platelets were stimulated by thrombin. These results prove the potential of these compounds as novel agents in a range of biological fields, indicating that a combination of L- and D- amino acids may prove more effective than an agent consisting solely of L-amino acids.
- Full Text:
- Date Issued: 2002
- Authors: Jamie, Hajierah
- Date: 2002
- Subjects: Pharmaceutical chemistry , Cyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11023 , http://hdl.handle.net/10948/281 , Pharmaceutical chemistry , Cyclic compounds
- Description: The isomers of cyclo(Trp-Pro) (cyclo(L-Trp-L-Pro), cyclo(L-Trp-D-Pro), cyclo(D-Trp-LPro) and cyclo(D-Trp-D-Pro)) have been successfully synthesized and screened for biological activity. High percentage yields were obtained by using the three phase synthesis system, which involves the synthesis of the intermediate protected linear dipeptides, followed by the removal of the protecting Boc groups. This step is followed by cyclization and crystallization of the isomers. The diketopiperazines rings of cyclo(L-Trp-L-Pro) and cyclo(D-Trp-D-Pro) contain cisamide bonds, while cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) contain trans-amide bonds. These bonds govern the conformation of the diketopiperazines ring. The isomers have shown different degrees of biological activity, possibly as a result of the orientation of the side chain of tryptophan and this difference in conformation, leading to varying interactions between isomer and a range of receptors. Under experimental conditions, 10-3 M cyclo(L-Trp-D-Pro) and cyclo(D-Trp-L-Pro) showed effective anticancer activity against the cervical cancer cell line, HeLa, resulting in a <50% reduction in cell viability. Cytotoxicity screening with cyclo(D-Trp-L-Pro) indicated that it was hepatocyte-specific in its toxicity, whilst the other isomers were cytotoxic against the other cell types tested. At 1mg/ml, cyclo(L-Trp-L-Pro) proved to be an effective antimicrobial agent against Gram positive bacteria, while cyclo(L-Trp-DPro) effectively inhibited the growth of the Gram negative bacteria, Esherichia coli. Cyclo(D-Trp-L-Pro) proved to be effective against Streptococcus, while cyclo(D-Trp-DPro) effectively reduced viability of the yeast, Candida albicans. Cyclo(D-Trp-L-Pro) was the only isomer to show Ca2+-channel antagonism, whilst the other isomers resulted in opening of the Ca2+-channel. No effects were observed on K+-channel activity for all the isomers tested. The isomers also proved to be valuable antiarrhythmic agents by effectively reducing the time spent in ventricular tachycardia and arrhythmia, as well as decreasing the time for the heart rate to return to a normal sinus rhythm. Furthermore, cyclo(L-Trp-D-Pro) showed positive chronotropic activity, while cyclo(D-Trp-L-Pro) ii showed negative chronotropic activity. In addition, cyclo(L-Trp-D-Pro) and cyclo(D-Trp- L-Pro) also increased the coronary flow rate. 0.125 1 mM Cyclo(L-Trp-D-Pro) decreased aggregation in washed platelets induced by thrombin. All isomers increased adhesion to an artificial surface when the platelets were stimulated by ADP, yet caused reduced adhesion when the platelets were stimulated by thrombin. These results prove the potential of these compounds as novel agents in a range of biological fields, indicating that a combination of L- and D- amino acids may prove more effective than an agent consisting solely of L-amino acids.
- Full Text:
- Date Issued: 2002
The variation of conditions of employment
- Authors: Horo, Lindile
- Date: 2002
- Subjects: Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11043 , http://hdl.handle.net/10948/282 , Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Description: This paper seeks to bring clarity to a number of issues that arise from a process resulting from the unilateral variation of terms and conditions of employment and the conflict management and dispute resolution processes. The variation of employment terms particularly when it is driven by one party to the employment relationship can cause instability, insecurity, confusion and uncertainty to the parties involved. The nature of work is not constant and therefore changes are inevitable. This then has an effect of bringing disorder not only to the employer-employee relationship but also to the labour relations balance. In many instances and depending on whether it is the employer or employee who propagates the changes, the reasons to alter the conditions are different. Employers usually cite operational or economic reasons that are meant for the survival of the business as the need to make the changes. From the employees’ side the changes are necessitated by reasons aimed at a move from protecting the favourable employment conditions already acquired to improving them or attaining more. In the event that the parties to the employment relationship do not agree to the changes proposed and implemented, a dispute usually arises. This results from the failure of a consultation process, negotiations, persuasion or collective bargaining in general. In essence such a dispute arises from absence of consent to the changes. The failure of a bargaining system requires the process to assume a new nature. The dispute resolution systems and the conflict management systems follow as both the appropriate and necessary steps. The bargaining power together with the intervention of the third party is at the centre of this phase. The parties, depending on the nature of the dispute, the conditions that iv are changed and who are affected by the changes, have choices on what dispute resolution mechanisms to employ. The choice made has a huge impact on both the outcome required in the form of recourse, how the dispute will be resolved or how the conflict will be managed. There is legislative intervention with regards to the resolution of the conflictual scenarios that arise from disputes on unilateral variation of terms and conditions of employment. There are also non-statutory measures available to the parties. The choices are vast as to when can the variation take place, the reasons for the changes, the parties involved, the possible dispute resolution mechanisms, what can be varied and whether the unilateral implementation can be viewed as fair.
- Full Text:
- Date Issued: 2002
- Authors: Horo, Lindile
- Date: 2002
- Subjects: Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11043 , http://hdl.handle.net/10948/282 , Labor laws and legislation -- South Africa , Labor disputes -- South Africa , Collective bargaining -- South Africa
- Description: This paper seeks to bring clarity to a number of issues that arise from a process resulting from the unilateral variation of terms and conditions of employment and the conflict management and dispute resolution processes. The variation of employment terms particularly when it is driven by one party to the employment relationship can cause instability, insecurity, confusion and uncertainty to the parties involved. The nature of work is not constant and therefore changes are inevitable. This then has an effect of bringing disorder not only to the employer-employee relationship but also to the labour relations balance. In many instances and depending on whether it is the employer or employee who propagates the changes, the reasons to alter the conditions are different. Employers usually cite operational or economic reasons that are meant for the survival of the business as the need to make the changes. From the employees’ side the changes are necessitated by reasons aimed at a move from protecting the favourable employment conditions already acquired to improving them or attaining more. In the event that the parties to the employment relationship do not agree to the changes proposed and implemented, a dispute usually arises. This results from the failure of a consultation process, negotiations, persuasion or collective bargaining in general. In essence such a dispute arises from absence of consent to the changes. The failure of a bargaining system requires the process to assume a new nature. The dispute resolution systems and the conflict management systems follow as both the appropriate and necessary steps. The bargaining power together with the intervention of the third party is at the centre of this phase. The parties, depending on the nature of the dispute, the conditions that iv are changed and who are affected by the changes, have choices on what dispute resolution mechanisms to employ. The choice made has a huge impact on both the outcome required in the form of recourse, how the dispute will be resolved or how the conflict will be managed. There is legislative intervention with regards to the resolution of the conflictual scenarios that arise from disputes on unilateral variation of terms and conditions of employment. There are also non-statutory measures available to the parties. The choices are vast as to when can the variation take place, the reasons for the changes, the parties involved, the possible dispute resolution mechanisms, what can be varied and whether the unilateral implementation can be viewed as fair.
- Full Text:
- Date Issued: 2002
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