An investigation into some learning and teaching problems of biology in Transkei senior secondary schools
- Authors: Matoti, Sheila Nokuthula
- Date: 1990
- Subjects: Education, Secondary Biology -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1349 , http://hdl.handle.net/10962/d1001415
- Description: The aim of this study was to investigate some learning and teaching problems of biology in Transkei Senior Secondary schools. The research focussed mainly on Biochemistry. Biochemistry was treated in the context of biology as a whole to show its relevance to other sections of the syllabus. Questionnaires were administered to standard 10 pupils in 15 senior secondary schools selected randomly from the Central Region of Transkei. Further information on pupils' understanding of concepts taught in Biochemistry , was gained through use of concept tests and concept maps. Interviews were conducted with standard 9 and 10 biology teachers, Subject committee members, Examiners, Subject advisers, Lecturers from the University of Transkei and the Transkei Teachers' In-service College and pupils. Data obtained through the use of those research methods was analysed and discussed. Concept mapping as a teaching strategy was introduced to some standard 9 and 10 teachers who attended courses (biology) at The Transkei Teachers ' In-service College. Some suggestions and recommendations for the learning and teaching of biology were then made
- Full Text:
- Authors: Matoti, Sheila Nokuthula
- Date: 1990
- Subjects: Education, Secondary Biology -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1349 , http://hdl.handle.net/10962/d1001415
- Description: The aim of this study was to investigate some learning and teaching problems of biology in Transkei Senior Secondary schools. The research focussed mainly on Biochemistry. Biochemistry was treated in the context of biology as a whole to show its relevance to other sections of the syllabus. Questionnaires were administered to standard 10 pupils in 15 senior secondary schools selected randomly from the Central Region of Transkei. Further information on pupils' understanding of concepts taught in Biochemistry , was gained through use of concept tests and concept maps. Interviews were conducted with standard 9 and 10 biology teachers, Subject committee members, Examiners, Subject advisers, Lecturers from the University of Transkei and the Transkei Teachers' In-service College and pupils. Data obtained through the use of those research methods was analysed and discussed. Concept mapping as a teaching strategy was introduced to some standard 9 and 10 teachers who attended courses (biology) at The Transkei Teachers ' In-service College. Some suggestions and recommendations for the learning and teaching of biology were then made
- Full Text:
An investigation into some of the problems affecting the teaching and learning of biochemistry in Transkei Colleges of Education
- Authors: Qokweni, Patiswa
- Date: 1990
- Subjects: Biochemistry -- Study and teaching -- South Africa -- Transkei
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1350 , http://hdl.handle.net/10962/d1001416
- Description: The study investigated some of the problems experienced in the teaching and learning of biochemistry - a section in the Senior Certificate biology syllabus - in the Transkei Colleges of Education. Biochemistry is often labelled a difficult area, therefore, the study was an attempt to identify the problems encountered by biology teachers and lecturers in teaching biochemistry and by student-teachers in learning it. Questionnaires were admlninistered to final-year biology major student-teachers in the colleges, and to the biology teachers and college lecturers. Examiners and subject advisers for biology were interviewed. The questionnaires required the respondents to identify the following: 1. Areas of biochemistry they find difficult. 2. Areas of biochemistry they find easy to understand. 3. Possible reasons for the students' poor performance in biochemistry. 4. Possible suggestions for improvement. The student-teachers were further given a concept test to test their understanding of the concept 'photosynthesis'. After analysing the data, the findings were used to make some recommendations, in an attempt to improve the teaching of biochemistry by the teachers and lecturers and of the learning of biochemistry by the students
- Full Text:
- Authors: Qokweni, Patiswa
- Date: 1990
- Subjects: Biochemistry -- Study and teaching -- South Africa -- Transkei
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1350 , http://hdl.handle.net/10962/d1001416
- Description: The study investigated some of the problems experienced in the teaching and learning of biochemistry - a section in the Senior Certificate biology syllabus - in the Transkei Colleges of Education. Biochemistry is often labelled a difficult area, therefore, the study was an attempt to identify the problems encountered by biology teachers and lecturers in teaching biochemistry and by student-teachers in learning it. Questionnaires were admlninistered to final-year biology major student-teachers in the colleges, and to the biology teachers and college lecturers. Examiners and subject advisers for biology were interviewed. The questionnaires required the respondents to identify the following: 1. Areas of biochemistry they find difficult. 2. Areas of biochemistry they find easy to understand. 3. Possible reasons for the students' poor performance in biochemistry. 4. Possible suggestions for improvement. The student-teachers were further given a concept test to test their understanding of the concept 'photosynthesis'. After analysing the data, the findings were used to make some recommendations, in an attempt to improve the teaching of biochemistry by the teachers and lecturers and of the learning of biochemistry by the students
- Full Text:
An investigation into the nature and extent of erosion and sedimentation in the Maqalika Dam catchment, Maseru
- Authors: Ntsaba, 'Mankone 'Mabataung
- Date: 1990
- Subjects: Erosion -- Lesotho Sedimentation and deposition -- Lesotho Land use -- Lesotho -- History River sediments -- Lesotho
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4799 , http://hdl.handle.net/10962/d1001899
- Description: The study investigates the nature and extent of erosion and deposition in the Maqalika catchment, Maseru. Components of the study include (i) the re-construction of erosion and land use history in the catchment from 1961 to 1985, (li) determination of dominant factors or combinations of factors responsible for the observed erosion distribution at each date, (iii) the identification and evaluation of erosion and deposition features, and their spatial and temporal variations, and (iv) identification of socia-economic problems associated with observed erosion and deposition. Methods employed for the re-construction of erosion and land use history include the use of sequential aerial photography of 1961, 1979 and 1985, orthophoto maps and review of literature from past studies. It has been possible to map erosion and land use for the three time periods pinpointing areas of major change. Results are presented in map form showing the spatial distribution of each erosion class and each land use category. It was however not possible to derive any meaningful relationship between erosion distribution and land use, on the aforementioned maps. The only observation made from the comparison of the maps is that erosion degree and distribution sometimes changes with land use, while land use sometimes changes in response to erosion. Major land use changes are the conversion of agricultural land to urban land use, and grazing land. Due to the mnlti-dimensional nature of soil erosion, hand 'actor analysis was employed to determine which factors or combinations of factors were dominant at each date. Despite the extensive research on the various factors affecting erosion such as those used for the USLE and SLEMSA there is a growing uncertainty as to which factors are more important to erosion. Soil erodibility has been found to be a component of the major controlling factor combinations in all three periods under study. At each date erodibility combined with a number of other factors determined the observed erosion distribution. As suggested by Mosley (1980), Cambell (1985) and Coleman and Scatena (1986) sediment from a catchment is derived principally from spatially limited portions of the catchment. Likewise eroded sediment becomes deposited in spatially limited areas with special characteristics which encourage deposition. Aerial photographic survey aided by ground survey and oblique photographs were employed to identify sediment sources and sinks within the catchment. Some sediment sources are fIxed such as gully floors and sides, while some change location from time to time such as construction sites. An evaluation of portions of the catchment for their ability to supply and deliver sediment has shown that the most eroded areas are not the most active sediment sources. Sediment yield is limited by either supply or transport. Sediment yield was estimated using reservoir survey data which indicate that there is a high rate of soil loss from the catchment. One flaw of this method as a measure of soil loss is that it treats the measured sediment yield as if it were contributed uniformly from the basin. This method however affords the researcher to estimate minimum erosion rates, taking into account that large amounts of sediment are stored at various places within the catchment. The possible socio-economic consequences of erosion and deposition have been identified. These include loss of cropland, destruction of roads and building sites which require methods of reclamation, sedimentation of small reservoirs and ponds, and the formation of gully bottom fills which are potential sediment sources. Conservation measures presently applied in the catchment are assessed and found to be irrelavant to the present erosion problem. Data from the reservoir survey revealed that the estimated rate of soil loss is more important to on-site erosion damage than to off-site damage in the form of the sedimentation of Maqalika reservoir. Appropriate conservation measures such as those suggested by Amimoto (1981) would be relevant to the study area, however the main constraint in their implementation would be lack of legislation and the absence of a sound land use policy. It is therefore concluded that the present land use situation which does not take into consideration the physical constraints of the catchment is partly responsible for accelarated erosion in the catchment.
- Full Text:
- Authors: Ntsaba, 'Mankone 'Mabataung
- Date: 1990
- Subjects: Erosion -- Lesotho Sedimentation and deposition -- Lesotho Land use -- Lesotho -- History River sediments -- Lesotho
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4799 , http://hdl.handle.net/10962/d1001899
- Description: The study investigates the nature and extent of erosion and deposition in the Maqalika catchment, Maseru. Components of the study include (i) the re-construction of erosion and land use history in the catchment from 1961 to 1985, (li) determination of dominant factors or combinations of factors responsible for the observed erosion distribution at each date, (iii) the identification and evaluation of erosion and deposition features, and their spatial and temporal variations, and (iv) identification of socia-economic problems associated with observed erosion and deposition. Methods employed for the re-construction of erosion and land use history include the use of sequential aerial photography of 1961, 1979 and 1985, orthophoto maps and review of literature from past studies. It has been possible to map erosion and land use for the three time periods pinpointing areas of major change. Results are presented in map form showing the spatial distribution of each erosion class and each land use category. It was however not possible to derive any meaningful relationship between erosion distribution and land use, on the aforementioned maps. The only observation made from the comparison of the maps is that erosion degree and distribution sometimes changes with land use, while land use sometimes changes in response to erosion. Major land use changes are the conversion of agricultural land to urban land use, and grazing land. Due to the mnlti-dimensional nature of soil erosion, hand 'actor analysis was employed to determine which factors or combinations of factors were dominant at each date. Despite the extensive research on the various factors affecting erosion such as those used for the USLE and SLEMSA there is a growing uncertainty as to which factors are more important to erosion. Soil erodibility has been found to be a component of the major controlling factor combinations in all three periods under study. At each date erodibility combined with a number of other factors determined the observed erosion distribution. As suggested by Mosley (1980), Cambell (1985) and Coleman and Scatena (1986) sediment from a catchment is derived principally from spatially limited portions of the catchment. Likewise eroded sediment becomes deposited in spatially limited areas with special characteristics which encourage deposition. Aerial photographic survey aided by ground survey and oblique photographs were employed to identify sediment sources and sinks within the catchment. Some sediment sources are fIxed such as gully floors and sides, while some change location from time to time such as construction sites. An evaluation of portions of the catchment for their ability to supply and deliver sediment has shown that the most eroded areas are not the most active sediment sources. Sediment yield is limited by either supply or transport. Sediment yield was estimated using reservoir survey data which indicate that there is a high rate of soil loss from the catchment. One flaw of this method as a measure of soil loss is that it treats the measured sediment yield as if it were contributed uniformly from the basin. This method however affords the researcher to estimate minimum erosion rates, taking into account that large amounts of sediment are stored at various places within the catchment. The possible socio-economic consequences of erosion and deposition have been identified. These include loss of cropland, destruction of roads and building sites which require methods of reclamation, sedimentation of small reservoirs and ponds, and the formation of gully bottom fills which are potential sediment sources. Conservation measures presently applied in the catchment are assessed and found to be irrelavant to the present erosion problem. Data from the reservoir survey revealed that the estimated rate of soil loss is more important to on-site erosion damage than to off-site damage in the form of the sedimentation of Maqalika reservoir. Appropriate conservation measures such as those suggested by Amimoto (1981) would be relevant to the study area, however the main constraint in their implementation would be lack of legislation and the absence of a sound land use policy. It is therefore concluded that the present land use situation which does not take into consideration the physical constraints of the catchment is partly responsible for accelarated erosion in the catchment.
- Full Text:
Aspects of Shakespeare in post-colonial Africa
- Authors: Wright, Laurence
- Date: 1990
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455614 , vital:75443 , https://hdl.handle.net/10520/AJA1011582X_182
- Description: Two views capture in cameo the most obvious conflict over Shake-speare's presence in post-colonial Africa. The late Okot p'Bitek, when newly appointed as Director of Uganda's National Theatre, set tradi-tional drummers to play outside the building; he was, in David Rubadiri's words," challenging... the British Council, which thought it had exclusive rights to put Shakespeare there all the time instead of getting the ordi-nary people... to come and see local plays".
- Full Text:
- Authors: Wright, Laurence
- Date: 1990
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/455614 , vital:75443 , https://hdl.handle.net/10520/AJA1011582X_182
- Description: Two views capture in cameo the most obvious conflict over Shake-speare's presence in post-colonial Africa. The late Okot p'Bitek, when newly appointed as Director of Uganda's National Theatre, set tradi-tional drummers to play outside the building; he was, in David Rubadiri's words," challenging... the British Council, which thought it had exclusive rights to put Shakespeare there all the time instead of getting the ordi-nary people... to come and see local plays".
- Full Text:
Aspects of the biology of the infaunal bivalve Mollusc Solen cylindraceus (Hanley) in the Kariega estuary
- De Villiers, Casper Johannes
- Authors: De Villiers, Casper Johannes
- Date: 1990
- Subjects: Mollusks -- South Africa -- Eastern Cape Bivalves -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5639 , http://hdl.handle.net/10962/d1005321
- Description: Solen cylindraceus is an infaunal filter-feeding bivalve inhabiting the intertidal mud banks of many southern African estuaries. It is particularly abundant in the Kariega estuary (33°41'S; 26°42'E) where it reaches densities of 400m⁻² (192g shell-free dry wt. m⁻²). The Kariega is a permanently open, marine dominated estuary about 18km in length, and S. cylindraceus is most abundant in its middle and upper reaches. Some physical characteristics of the estuary (temperature, salinity, sediment and water turbidity) are described, and the possible role of these factors in determining the density and distribution of S. cylindraceus within the Kariega estuary, is discussed. The structure of the alimentary system, gills and labial palps of S. cylintfraceus is described, all of which showed no major variation from the "typical" eulamellibranchiate form. Solen cylintfraceus was found to be a euryhaline osmoconformer with a salinity tolerance range of 15-65%. When animals were removed from their burrows, osmotic equilibration of the haemolymph was rapid (1-2 hours). By contrast, in animals left undisturbed in their burrows, osmotic equilibration was retarded (72-204 hours). It is suggested that the observed decrease in the rate of change of haemolymph osmolarity for animals in their burrows is linked to the stability of the interstitial salinity. A temperature tolerance range of 5-44°C was determined for S. cylintfraceus (in situ), in which prolonged exposure to 5°C and 40-45°C (12-36 hours respectively) resulted in a decreased burrowing ability, coma and death. Animal burrowing responses were not affected by temperatures in the range 15-35°C. Field experiments were carried out over several tidal cycles, in which the measurement of crystalline style volume was used as a means of assessing extracellular digestive activity. No major variation in style volume was recorded and it appeared that S. cylindraceus did not exhibit any cyclical pattern of style dissolution and regeneration. It is suggested that S. cylindraceus feeds continuously from the water column during high tide and possibly within its burrow, at or below the water table, during low tide. At a suspensoid concentration of 5Omg l⁻¹, S. cylindraceus was found to filter water almost continuously (90-95% of the time). Time spent filtering dropped to 68% at 100mg l⁻¹ and 32% at 500mg l⁻¹. Filtration rates for summer collected animals (25°C) were 22.86 ± 4.36ml min.⁻¹, some 3ml min.⁻¹ greater than that recorded for winter (16°C) collected animals. Filtration rate may be expressed as a function of shell length by the equations: y=0.247x¹̇⁰⁶⁶ (winter) and y=0.758x⁰̇⁸²⁶ (summer). Solen cylindraceus was capable of acclimating its filtration rate to both high and low temperatures under laboratory conditions. Filtration rate exhibited a thermal optimum in the range 15-35°C, declining at higher and lower temperatures. Q₁₀ values of filtration decreased rapidly from greater than 4 to less than 2, when the thermal optimum was reached. Maximum rates generally occurred at approximately 5°C above the temperature to which the animal had been acclimated. Optimal filtration rates (19-23ml min.⁻¹) were recorded in the salinity range 15-45%. When subjected to abrupt changes in salinity, filtration rates were immediately depressed. The extent and duration of these decreased filtration rates were dependent upon the magnitude and direction of salinity change, and were always less in animals exposed to hyper- than hyposaline conditions. Animals exposed to increased temperature and simultaneous elevated or unchanged salinity, showed a slight increase in filtration rate followed by rapid acclimation. A decrease in both temperature and salinity resulted in an initial decrease in filtration rate and a longer acclimation period. The ability of S. cylindraceus to acclimate fully within a wide temperature and salinity range, and to filter maximally in hypersaline conditions may, in part, explain its unusually high abundance in the Kariega estuary, despite it being close to the southernmost limit of the animal's geographical distribution. No significant difference in flItration rate was recorded at suspensoid concentrations of 5-100mg 1⁻¹. However, at 250 and 500mg l⁻¹ filtration rates decreased significantly, and coincided with increased levels of pseudofaecal production. Solen cylindraceus retained particles down to 2.5-3.0µm with great efficiency (ca. 60-90% efficiency). Below this particle size, retention efficiency decreased rapidly and a net production of particles was recorded below 1.51µm. Particle retention was independent of temperature (15 and 25°C) and salinity (15 and 35%). Use was made of stable carbon isotope analyses (¹³C/¹²C ratios) in an attempt to determine the important food sources of S. cylindraceus within the Kariega estuary. The results obtained demonstrated an enrichment in δ¹³ values for S. cylindraceus from the upper (-27.9%) to the middle (-25%c) and lower (-21.6%o ) reaches of the estuary, with no seasonal variation apparent. The bivalve was substantially more depleted in ¹³C relative to the dominant aquatic macrophytes Zostera capensis (-9.1 to -15.6%o) and Spartina maritima (-12.5%o). The use of δ¹³ alone, however, to unequivocally "pin point" specific food sources of a filter feeder in a predominantly detritus based food web, is limited. It is suggested that in the Kariega estuary, riparian litter and other terrestrially derived vegetation contribute to the carbon pool. A possible contribution of ¹³C depleted food sources via chemoautotrophic and/or anaerobic pathways, to the diet of S. cylindraceus, is suggested.
- Full Text:
- Authors: De Villiers, Casper Johannes
- Date: 1990
- Subjects: Mollusks -- South Africa -- Eastern Cape Bivalves -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5639 , http://hdl.handle.net/10962/d1005321
- Description: Solen cylindraceus is an infaunal filter-feeding bivalve inhabiting the intertidal mud banks of many southern African estuaries. It is particularly abundant in the Kariega estuary (33°41'S; 26°42'E) where it reaches densities of 400m⁻² (192g shell-free dry wt. m⁻²). The Kariega is a permanently open, marine dominated estuary about 18km in length, and S. cylindraceus is most abundant in its middle and upper reaches. Some physical characteristics of the estuary (temperature, salinity, sediment and water turbidity) are described, and the possible role of these factors in determining the density and distribution of S. cylindraceus within the Kariega estuary, is discussed. The structure of the alimentary system, gills and labial palps of S. cylintfraceus is described, all of which showed no major variation from the "typical" eulamellibranchiate form. Solen cylintfraceus was found to be a euryhaline osmoconformer with a salinity tolerance range of 15-65%. When animals were removed from their burrows, osmotic equilibration of the haemolymph was rapid (1-2 hours). By contrast, in animals left undisturbed in their burrows, osmotic equilibration was retarded (72-204 hours). It is suggested that the observed decrease in the rate of change of haemolymph osmolarity for animals in their burrows is linked to the stability of the interstitial salinity. A temperature tolerance range of 5-44°C was determined for S. cylintfraceus (in situ), in which prolonged exposure to 5°C and 40-45°C (12-36 hours respectively) resulted in a decreased burrowing ability, coma and death. Animal burrowing responses were not affected by temperatures in the range 15-35°C. Field experiments were carried out over several tidal cycles, in which the measurement of crystalline style volume was used as a means of assessing extracellular digestive activity. No major variation in style volume was recorded and it appeared that S. cylindraceus did not exhibit any cyclical pattern of style dissolution and regeneration. It is suggested that S. cylindraceus feeds continuously from the water column during high tide and possibly within its burrow, at or below the water table, during low tide. At a suspensoid concentration of 5Omg l⁻¹, S. cylindraceus was found to filter water almost continuously (90-95% of the time). Time spent filtering dropped to 68% at 100mg l⁻¹ and 32% at 500mg l⁻¹. Filtration rates for summer collected animals (25°C) were 22.86 ± 4.36ml min.⁻¹, some 3ml min.⁻¹ greater than that recorded for winter (16°C) collected animals. Filtration rate may be expressed as a function of shell length by the equations: y=0.247x¹̇⁰⁶⁶ (winter) and y=0.758x⁰̇⁸²⁶ (summer). Solen cylindraceus was capable of acclimating its filtration rate to both high and low temperatures under laboratory conditions. Filtration rate exhibited a thermal optimum in the range 15-35°C, declining at higher and lower temperatures. Q₁₀ values of filtration decreased rapidly from greater than 4 to less than 2, when the thermal optimum was reached. Maximum rates generally occurred at approximately 5°C above the temperature to which the animal had been acclimated. Optimal filtration rates (19-23ml min.⁻¹) were recorded in the salinity range 15-45%. When subjected to abrupt changes in salinity, filtration rates were immediately depressed. The extent and duration of these decreased filtration rates were dependent upon the magnitude and direction of salinity change, and were always less in animals exposed to hyper- than hyposaline conditions. Animals exposed to increased temperature and simultaneous elevated or unchanged salinity, showed a slight increase in filtration rate followed by rapid acclimation. A decrease in both temperature and salinity resulted in an initial decrease in filtration rate and a longer acclimation period. The ability of S. cylindraceus to acclimate fully within a wide temperature and salinity range, and to filter maximally in hypersaline conditions may, in part, explain its unusually high abundance in the Kariega estuary, despite it being close to the southernmost limit of the animal's geographical distribution. No significant difference in flItration rate was recorded at suspensoid concentrations of 5-100mg 1⁻¹. However, at 250 and 500mg l⁻¹ filtration rates decreased significantly, and coincided with increased levels of pseudofaecal production. Solen cylindraceus retained particles down to 2.5-3.0µm with great efficiency (ca. 60-90% efficiency). Below this particle size, retention efficiency decreased rapidly and a net production of particles was recorded below 1.51µm. Particle retention was independent of temperature (15 and 25°C) and salinity (15 and 35%). Use was made of stable carbon isotope analyses (¹³C/¹²C ratios) in an attempt to determine the important food sources of S. cylindraceus within the Kariega estuary. The results obtained demonstrated an enrichment in δ¹³ values for S. cylindraceus from the upper (-27.9%) to the middle (-25%c) and lower (-21.6%o ) reaches of the estuary, with no seasonal variation apparent. The bivalve was substantially more depleted in ¹³C relative to the dominant aquatic macrophytes Zostera capensis (-9.1 to -15.6%o) and Spartina maritima (-12.5%o). The use of δ¹³ alone, however, to unequivocally "pin point" specific food sources of a filter feeder in a predominantly detritus based food web, is limited. It is suggested that in the Kariega estuary, riparian litter and other terrestrially derived vegetation contribute to the carbon pool. A possible contribution of ¹³C depleted food sources via chemoautotrophic and/or anaerobic pathways, to the diet of S. cylindraceus, is suggested.
- Full Text:
Aspects of the nutritional physiology and dietary requirements of juvenile and adult sharptooth catfish, Clarias Gariepinus (Pisces : clariidae)
- Authors: Uys, Wynand
- Date: 1990
- Subjects: Clariidae Catfishes Catfishes -- Nutrition-requirements Clarias
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5225 , http://hdl.handle.net/10962/d1005068
- Description: Past and current research on the biology and culture of the sharptooth catfish (Clarias gariepinus) has stimulated the development of its commercial production. At the inception of this project in 1985, it was decided that the development of an optimal dry feed was the most important step in developing a more complete culture technology for the species. The objectives of the project were, therefore, to investigate aspects of the nutritional physiology and dietary requirements of the species to provide the necessary information for the formulation of optimum economical feeds. A review of the natural feeding biology of the species provided valuable information with regard to its food preferences. From this information, and by estimating the nutritional composition of its preferred natural diet, it could be concluded that the animal requires a relatively high dietary protein content. This conclusion was substantiated by studies of the functional morphology of the digestive system (gross and fine structure). The characteristics of the digestive system and external anatomy were found to be typical of an opportunistic, omnivorous predator. The ontogenetic development of the digestive system is relatively fast, and enables the utilization of a variety of diets efficiently from an early stage. Since the ability of an animal to digest a given substance is predominantly dependent on the presence of appropriate enzymes the quantification and characterization of C. gariepinus digestive enzyme activities were investigated on an experimental basis. This work revealed that the animal has relatively high levels of digestive enzyme activities, and that its proteolytic enzyme activities correspond with those of other carnivorous fishes, while its starch digesting abilities correspond with those of specialized herbivores. Also, the high levels of lysozyme and alkaline phosphatase indicate an adaptation to detritivory, making this fish a truly opportunistic omnivore. Evidence was found to suggest that sharptooth catfish are able to re-absorb secreted digestive enzymes in the posterior section of its intestinal tract. It was shown that digestive enzyme activities were induced by food intake, and that no inherent rhythmicity in digestive activities seemed to occur. The development of digestive enzyme systems in the early life history of this animal was found to be also extremely rapid (complete within 10-16 days after hatching). It was also shown that artificial dry feed stimulates higher levels of digestive enzyme activities in larvae and juveniles than natural food. Although increased cellulase activity was found in larvae and juveniles that were fed on live zooplankton, the relative contribution of exogenous prey enzymes to protein digestion could not be ascertained. Specific nutritional requirements were investigated by means of feeding trials. The results of these trials confirmed the above indications regarding the dietary requirements of sharptooth catfish. It was concluded that for optimal growth and production performance, this animal requires a dietary protein content of 40-42%, a dietary lipid content of 10-12% and that diets should contain 14-16 kJ/g digestible energy. The optimum protein-to-energy ratio was found to be 26-29mg protein per kJ of digestible energy. Dietary requirements are evidently the same for juveniles and adults, except that younger fish require higher relative feeding levels. Finally, practical feed formulations were evaluated in terms of their economic feasibility. The results of these trials are presented along with recommendations on the formulation of commercial feeds for C. gariepinus. A computer program with which to implement least cost feed formulation by means of linear programming is provided.
- Full Text:
- Authors: Uys, Wynand
- Date: 1990
- Subjects: Clariidae Catfishes Catfishes -- Nutrition-requirements Clarias
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5225 , http://hdl.handle.net/10962/d1005068
- Description: Past and current research on the biology and culture of the sharptooth catfish (Clarias gariepinus) has stimulated the development of its commercial production. At the inception of this project in 1985, it was decided that the development of an optimal dry feed was the most important step in developing a more complete culture technology for the species. The objectives of the project were, therefore, to investigate aspects of the nutritional physiology and dietary requirements of the species to provide the necessary information for the formulation of optimum economical feeds. A review of the natural feeding biology of the species provided valuable information with regard to its food preferences. From this information, and by estimating the nutritional composition of its preferred natural diet, it could be concluded that the animal requires a relatively high dietary protein content. This conclusion was substantiated by studies of the functional morphology of the digestive system (gross and fine structure). The characteristics of the digestive system and external anatomy were found to be typical of an opportunistic, omnivorous predator. The ontogenetic development of the digestive system is relatively fast, and enables the utilization of a variety of diets efficiently from an early stage. Since the ability of an animal to digest a given substance is predominantly dependent on the presence of appropriate enzymes the quantification and characterization of C. gariepinus digestive enzyme activities were investigated on an experimental basis. This work revealed that the animal has relatively high levels of digestive enzyme activities, and that its proteolytic enzyme activities correspond with those of other carnivorous fishes, while its starch digesting abilities correspond with those of specialized herbivores. Also, the high levels of lysozyme and alkaline phosphatase indicate an adaptation to detritivory, making this fish a truly opportunistic omnivore. Evidence was found to suggest that sharptooth catfish are able to re-absorb secreted digestive enzymes in the posterior section of its intestinal tract. It was shown that digestive enzyme activities were induced by food intake, and that no inherent rhythmicity in digestive activities seemed to occur. The development of digestive enzyme systems in the early life history of this animal was found to be also extremely rapid (complete within 10-16 days after hatching). It was also shown that artificial dry feed stimulates higher levels of digestive enzyme activities in larvae and juveniles than natural food. Although increased cellulase activity was found in larvae and juveniles that were fed on live zooplankton, the relative contribution of exogenous prey enzymes to protein digestion could not be ascertained. Specific nutritional requirements were investigated by means of feeding trials. The results of these trials confirmed the above indications regarding the dietary requirements of sharptooth catfish. It was concluded that for optimal growth and production performance, this animal requires a dietary protein content of 40-42%, a dietary lipid content of 10-12% and that diets should contain 14-16 kJ/g digestible energy. The optimum protein-to-energy ratio was found to be 26-29mg protein per kJ of digestible energy. Dietary requirements are evidently the same for juveniles and adults, except that younger fish require higher relative feeding levels. Finally, practical feed formulations were evaluated in terms of their economic feasibility. The results of these trials are presented along with recommendations on the formulation of commercial feeds for C. gariepinus. A computer program with which to implement least cost feed formulation by means of linear programming is provided.
- Full Text:
Between freedom and givenness: (a study of the hermeneutical consequences of the concept of canon for the authority of scripture)
- Authors: Latham, Jonathan Cyril
- Date: 1990
- Subjects: Bible -- Evidences, authority, etc. , Authority -- Religious aspects , Canon (Literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1216 , http://hdl.handle.net/10962/d1001546
- Description: The aim of this thesis is to arrive at an understanding of the authority of scripture that is able to accommodate both a faith perspective and the fruits of the historical-critical approach to the New Testament. Put differently, the aim of this thesis is the pursuit of a specifically christian, faith-promoting, reading of the New Testament whilst still enjoying the benefit, in an as uncompromised a form as possible, of the historical- critical approach. In a sense it may be said that this task, given that the roots of both the historical-critical approach and modern Western culture are deeply imbedded in Rationalism, is equivalent to the basic hermeneutical question of whether it is possible to interpret scripture relevantly from within a cultural web of meaning that does not readily accommodate that embodied in the New Testament. In section one of this dissertation we present a characteristic depiction, based on the historical-critical theory of literature, of the authority of the New Testament. This is followed by a brief assessment that makes explicit why the historical- critical approach is not conducive to the adoption of a faith perspective on these writings. In section two, still and inevitably based on critical foundations, we adopt a perspective that is more sympathetic to faith and that seeks to discover in the concerns evidenced in the canonical process, when traditions about Jesus gradually took on more complex and stable forms, culminating in the canon of the New Testament, guidelines in helping us to deal with the problem with which this study is concerned . In the specific example of the rather ordinary concerns underlying the unusual history of the pericope de adultera (John 7:53-8:11), examined against the background of the interests underlying the canonical process, it becomes clear that christians from the very beginning faced a dilemma not unlike that with which the historical-critical approach confronts us. They had to interpret afresh, and faithfully, the traditions in order to meet the demands of situations that had never been foreseen by earlier tradents. In this respect, therefore, the history of the pericope de adultera presents us with an ongoing struggle to hold in tension the demands of new contexts with the imperative of strict continuity with Jesus. In section three, on the basis of the foundation of the authority of scripture in strict continuity with Jesus combined with the contextual reinterpretation of the tradition, the social sciences are employed. Using the social sciences, it is discovered that the two contradictory approaches that we wish to reconcile form part of two different models for interpreting reality. It is on this basis, and made possible by the common culture underlying these opposing models and by the common contact with an unspecified common core of concrete reality, that a solution is proposed in terms of a complex 'fusion of horizons', promoted by a 'precipitative environment'. In the conclusion our solution is decisively aligned with the concerns evidenced in the canonical process
- Full Text:
- Authors: Latham, Jonathan Cyril
- Date: 1990
- Subjects: Bible -- Evidences, authority, etc. , Authority -- Religious aspects , Canon (Literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1216 , http://hdl.handle.net/10962/d1001546
- Description: The aim of this thesis is to arrive at an understanding of the authority of scripture that is able to accommodate both a faith perspective and the fruits of the historical-critical approach to the New Testament. Put differently, the aim of this thesis is the pursuit of a specifically christian, faith-promoting, reading of the New Testament whilst still enjoying the benefit, in an as uncompromised a form as possible, of the historical- critical approach. In a sense it may be said that this task, given that the roots of both the historical-critical approach and modern Western culture are deeply imbedded in Rationalism, is equivalent to the basic hermeneutical question of whether it is possible to interpret scripture relevantly from within a cultural web of meaning that does not readily accommodate that embodied in the New Testament. In section one of this dissertation we present a characteristic depiction, based on the historical-critical theory of literature, of the authority of the New Testament. This is followed by a brief assessment that makes explicit why the historical- critical approach is not conducive to the adoption of a faith perspective on these writings. In section two, still and inevitably based on critical foundations, we adopt a perspective that is more sympathetic to faith and that seeks to discover in the concerns evidenced in the canonical process, when traditions about Jesus gradually took on more complex and stable forms, culminating in the canon of the New Testament, guidelines in helping us to deal with the problem with which this study is concerned . In the specific example of the rather ordinary concerns underlying the unusual history of the pericope de adultera (John 7:53-8:11), examined against the background of the interests underlying the canonical process, it becomes clear that christians from the very beginning faced a dilemma not unlike that with which the historical-critical approach confronts us. They had to interpret afresh, and faithfully, the traditions in order to meet the demands of situations that had never been foreseen by earlier tradents. In this respect, therefore, the history of the pericope de adultera presents us with an ongoing struggle to hold in tension the demands of new contexts with the imperative of strict continuity with Jesus. In section three, on the basis of the foundation of the authority of scripture in strict continuity with Jesus combined with the contextual reinterpretation of the tradition, the social sciences are employed. Using the social sciences, it is discovered that the two contradictory approaches that we wish to reconcile form part of two different models for interpreting reality. It is on this basis, and made possible by the common culture underlying these opposing models and by the common contact with an unspecified common core of concrete reality, that a solution is proposed in terms of a complex 'fusion of horizons', promoted by a 'precipitative environment'. In the conclusion our solution is decisively aligned with the concerns evidenced in the canonical process
- Full Text:
Blanching activities of betamethasone 17-valerate formulations: effect of the dosage form on topical drug availability
- Smith, Eric W, Meyer, Eric, Haigh, John M
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6432 , http://hdl.handle.net/10962/d1006602
- Description: The blanching activities of Betnovate© cream, lotion, ointment and scalp application (each containing 0.1 % betamethasone (as the 17-valerate)) were determined using healthy human subjects over a 32 h period in both the occludedand unoccluded modes. Considering that allfour formulation types contained the same label concentration of corticosteroid,it may bepresumed that theformulations would show similar topical drug availability: this was, however, not found to be the case. The scalp application demonstrated the highest topical availability in both the occluded and unoccluded modes. The lotion formulation showed the greatest increase in topical availability on occlusion and the ointment formulation was the least sensitive to the effects of occlusion. These differences, due solely to the effects of the vehicle, may have important clinical implications.
- Full Text:
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6432 , http://hdl.handle.net/10962/d1006602
- Description: The blanching activities of Betnovate© cream, lotion, ointment and scalp application (each containing 0.1 % betamethasone (as the 17-valerate)) were determined using healthy human subjects over a 32 h period in both the occludedand unoccluded modes. Considering that allfour formulation types contained the same label concentration of corticosteroid,it may bepresumed that theformulations would show similar topical drug availability: this was, however, not found to be the case. The scalp application demonstrated the highest topical availability in both the occluded and unoccluded modes. The lotion formulation showed the greatest increase in topical availability on occlusion and the ointment formulation was the least sensitive to the effects of occlusion. These differences, due solely to the effects of the vehicle, may have important clinical implications.
- Full Text:
Bulimia Nervosa: a case study in cognitive psychotherapy
- Authors: Kanfer, Josephine
- Date: 1990
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192988 , vital:45287
- Description: This project uses the case-study method to illustrate the application of integrating varied accepted modes of psychotherapeutic interventions. It concentrates on the first 22 out-patient sessions of therapy with a diagnosed bulimic, spanning a 6 month period. A brief summary of the subsequent 10 follow-up sessions is also given. The case presented is of a 22 year old female student diagnosed as bulimic (of 7 year duration), dysthymic and with a dependent personality disorder. She has symptoms of anxiety. She has a history of anorexia nervosa. Fairburn's (1985) cognitive-behavioural programme for bulimia was used initially. Its structured framework with the emphasis on the eating behaviour was an essential aspect in contributing to the success of the initial phase of the therapy. This patient had had previously experienced 8 sessions of non-directive depth psychotherapy which had confused and compounded her problems. The structure had provided her with a sense of control. In implementing the second stage of Fairburn's programme, where the focus is cognitive, the patient could no longer work in this this structured manner. The attempts to implement the standard cognitive techniques provided the catalyst for activating deeper underlying emotions and cognitions. Furthermore, this gave impetus to work actively with the interpersonal aspect of the therapeutic relationship. Young's (1989) model for identifying Early Maladaptive Schemas could be applied. The focus then moved from the behaviours and dealt with these schemas as activated in the therapeutic relationship. The patient was able to make links to her family and her past. The therapy proved successful, as not only were the behavioural symptoms alleviated, but also the patient's interpersonal problems which underlay her personality disorder were accessed. The patient had become more self-assertive, her mood had improved considerably, she was less concerned with body image and more accepting of herself. She had become more reality based and her interpersonal relational abi1ity had improved. , Thesis (MA) -- Faculty of Humanities, Psychology, 1990
- Full Text:
- Authors: Kanfer, Josephine
- Date: 1990
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192988 , vital:45287
- Description: This project uses the case-study method to illustrate the application of integrating varied accepted modes of psychotherapeutic interventions. It concentrates on the first 22 out-patient sessions of therapy with a diagnosed bulimic, spanning a 6 month period. A brief summary of the subsequent 10 follow-up sessions is also given. The case presented is of a 22 year old female student diagnosed as bulimic (of 7 year duration), dysthymic and with a dependent personality disorder. She has symptoms of anxiety. She has a history of anorexia nervosa. Fairburn's (1985) cognitive-behavioural programme for bulimia was used initially. Its structured framework with the emphasis on the eating behaviour was an essential aspect in contributing to the success of the initial phase of the therapy. This patient had had previously experienced 8 sessions of non-directive depth psychotherapy which had confused and compounded her problems. The structure had provided her with a sense of control. In implementing the second stage of Fairburn's programme, where the focus is cognitive, the patient could no longer work in this this structured manner. The attempts to implement the standard cognitive techniques provided the catalyst for activating deeper underlying emotions and cognitions. Furthermore, this gave impetus to work actively with the interpersonal aspect of the therapeutic relationship. Young's (1989) model for identifying Early Maladaptive Schemas could be applied. The focus then moved from the behaviours and dealt with these schemas as activated in the therapeutic relationship. The patient was able to make links to her family and her past. The therapy proved successful, as not only were the behavioural symptoms alleviated, but also the patient's interpersonal problems which underlay her personality disorder were accessed. The patient had become more self-assertive, her mood had improved considerably, she was less concerned with body image and more accepting of herself. She had become more reality based and her interpersonal relational abi1ity had improved. , Thesis (MA) -- Faculty of Humanities, Psychology, 1990
- Full Text:
Chemical and spectroscopic studies of the capsular polysaccharides of some klebsiella and escherichia coli serotypes
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
- Full Text:
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
- Full Text:
Cognitive therapy and the restructuring of early memories through guided imagery
- Authors: Edwards, David J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6241 , http://hdl.handle.net/10962/d1007853
- Description: This article describes the application of a guided imagery psychodrama technique to emotionally charged early memories. Such memories provide access to core schemata about the self and social relationships. Two case studies illustrate how the imagery technique enables the therapist to identify and restructure key cognitions out of which the schemata are constructed. The need for techniques to modify developmentally primitive schemata is discussed. Examples are given of ways to assist the patient in confronting the strong affect that may be aroused and in dealing with cognitions that block the process. Effectiveness is discussed in terms of the contribution of a guided imagery session to the overall process of ''learning to learn'' that takes place in cognitive psychotherapy.
- Full Text: false
- Authors: Edwards, David J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6241 , http://hdl.handle.net/10962/d1007853
- Description: This article describes the application of a guided imagery psychodrama technique to emotionally charged early memories. Such memories provide access to core schemata about the self and social relationships. Two case studies illustrate how the imagery technique enables the therapist to identify and restructure key cognitions out of which the schemata are constructed. The need for techniques to modify developmentally primitive schemata is discussed. Examples are given of ways to assist the patient in confronting the strong affect that may be aroused and in dealing with cognitions that block the process. Effectiveness is discussed in terms of the contribution of a guided imagery session to the overall process of ''learning to learn'' that takes place in cognitive psychotherapy.
- Full Text: false
Cognitive-behavioral and existential-phenomenological approaches to therapy : complementary or conflicting paradigms?
- Authors: Edwards, David J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6242 , http://hdl.handle.net/10962/d1007854
- Description: The relationship between the cognitive-behavioral and existential-phenomenological traditions in therapy is examined. While Beck cites phenomenological writers such as Heidegger, Husserl, and Binswanger, he does not initiate any dialogue with this tradition in depth. Parallels are drawn between the goals of psychotherapy as outlined by Rogers and goals identified in the contemporary cognitive-behavioral literature, between cognitive therapy's approach to clients' underlying assumptions and the phenomenological reduction as described by Husserl, and between a shared acceptance of the therapeutic use of the client-therapist interaction. While, in both approaches, therapists take on an educative role, in each approach a different aspect of the learning process is focused on. Phenomenological therapy's attitude to reality testing, the dangers of a directive stance by the therapist, the conflict between empathy and rational dialogue, and cognitive therapy's view of emotion are also discussed. The complementarity between the two approaches is emphasized and a continuing dialogue recommended.
- Full Text:
- Authors: Edwards, David J A
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6242 , http://hdl.handle.net/10962/d1007854
- Description: The relationship between the cognitive-behavioral and existential-phenomenological traditions in therapy is examined. While Beck cites phenomenological writers such as Heidegger, Husserl, and Binswanger, he does not initiate any dialogue with this tradition in depth. Parallels are drawn between the goals of psychotherapy as outlined by Rogers and goals identified in the contemporary cognitive-behavioral literature, between cognitive therapy's approach to clients' underlying assumptions and the phenomenological reduction as described by Husserl, and between a shared acceptance of the therapeutic use of the client-therapist interaction. While, in both approaches, therapists take on an educative role, in each approach a different aspect of the learning process is focused on. Phenomenological therapy's attitude to reality testing, the dangers of a directive stance by the therapist, the conflict between empathy and rational dialogue, and cognitive therapy's view of emotion are also discussed. The complementarity between the two approaches is emphasized and a continuing dialogue recommended.
- Full Text:
Commission of Inquiry into Oukasie Violence
- UDF
- Authors: UDF
- Date: 1990
- Subjects: UDF
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/250651 , vital:52035
- Description: In June 1990, the United Democratic Front [UDF] appointed Brian Cumin, National Director of Lawyers for Human Rights as Commissioner to investigate and report on the reasons for the violence in Oukasie Township, Brits, since February 1986. Brian Cumin was empowered to appoint additional Commissioners to assist him. David Bam and Mpho Molefe, both practising Attorneys in Pretoria were duly appointed as co-commissioners. As part of their report on the reasons for the violence in Oukasie, the Commissioners have taken the liberty of making recommendations to the United Democratic Front.
- Full Text:
- Authors: UDF
- Date: 1990
- Subjects: UDF
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/250651 , vital:52035
- Description: In June 1990, the United Democratic Front [UDF] appointed Brian Cumin, National Director of Lawyers for Human Rights as Commissioner to investigate and report on the reasons for the violence in Oukasie Township, Brits, since February 1986. Brian Cumin was empowered to appoint additional Commissioners to assist him. David Bam and Mpho Molefe, both practising Attorneys in Pretoria were duly appointed as co-commissioners. As part of their report on the reasons for the violence in Oukasie, the Commissioners have taken the liberty of making recommendations to the United Democratic Front.
- Full Text:
Community-based co-operative ventures in Port Elizabeth
- Authors: Davies, William J
- Date: 1990
- Subjects: Cities and towns -- Africa Cooperative societies Economic development Producer cooperatives Port Elizabeth (South Africa) -- Economic conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2329 , vital:20276 , ISBN 0868102032
- Description: This Working Paper reports on the results of an investigation into community-based co-operative ventures in Port Elizabeth. It represents part of an on-going research programme dealing with Black economic development undertaken by the Development Studies Unit (DSU) at Rhodes University. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Authors: Davies, William J
- Date: 1990
- Subjects: Cities and towns -- Africa Cooperative societies Economic development Producer cooperatives Port Elizabeth (South Africa) -- Economic conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2329 , vital:20276 , ISBN 0868102032
- Description: This Working Paper reports on the results of an investigation into community-based co-operative ventures in Port Elizabeth. It represents part of an on-going research programme dealing with Black economic development undertaken by the Development Studies Unit (DSU) at Rhodes University. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
COSATU Regional education programme
- COSATU
- Authors: COSATU
- Date: 1990
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/154403 , vital:39695
- Description: This document should be used by ail of us involved in Education as a basis for discussion on organising education in the Federation. We have pulled together all the relevant information and reccommen- dations which we hope will assist Led- comm, Educators and our constitutional structures in understanding what our tasks are in the locals and in affiliates. The Redcomm agreed that an Education Programme must go beyond being just a number of workshops and seminars. It must be a dynamic process which must contribute to the strengthening of our structures, improving the quality of our debates and promoting leadership of the working class in our struggle for democracy.
- Full Text:
- Authors: COSATU
- Date: 1990
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/154403 , vital:39695
- Description: This document should be used by ail of us involved in Education as a basis for discussion on organising education in the Federation. We have pulled together all the relevant information and reccommen- dations which we hope will assist Led- comm, Educators and our constitutional structures in understanding what our tasks are in the locals and in affiliates. The Redcomm agreed that an Education Programme must go beyond being just a number of workshops and seminars. It must be a dynamic process which must contribute to the strengthening of our structures, improving the quality of our debates and promoting leadership of the working class in our struggle for democracy.
- Full Text:
Dealing with distress: a medical anthropological analysis of the search for health in a rural Transkeian village
- Authors: Simon, Christian Michael
- Date: 1990
- Subjects: Medical care -- South Africa -- Transkei -- Jotelo , Poor -- Health and hygiene -- South Africa -- Transkei , Transkei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2082 , http://hdl.handle.net/10962/d1001599
- Description: This study aims to characterize and understand the search for health in a rural Transkeian community. It begins with the observation that the people of Jotelo have to negotiate considerable hardships in their daily lives. These hardships include the impact of malnutrition, undernourishment and a wide range of diseases like tuberculosis, typhoid and gastro-enteritis. To survive ill-health, people develop numerous practical strategies. Most significantly, they attempt to maximise availalble resources, like cash, their relations with others and local medical facilities. Hence the study attempts to characterize how and why patients select various kinds of therapy in their search for health. By focusing on patients' recourses to treatment, the study reveals that the search for health is as much a personal experience as it is a social and economic one. This idea is developed in an analysis of the links betw'een work, illness and social reproduction. The point which emerges from this discussion captures the central theme of the study: the search for health is a profoundly personal, social and economic experience. This notion is strengthened by an examination of the historical and contemporary nature of local health and health care. It is observed that health and health care is intimately linked to the local and wider political economy. This not only serves to contextualise the discussion on patients' actual experiences, but points to the fact that these experiences are part of wider processes. By depicting the search for health in this way, the study hopes to have illustrated what people do in times of illness and why. Yet it also claims to have gone beyond such a depiction. By abstracting from its findings, it aims to conclude that the search for health is not merely caused by various local and wider processes, to which it has referred. In other words, it hopes to avoid a deterministic view of patients' experiences in times of distress. Instead, it is argued that the search for health is ultimately an integral part of the local and wider economic and political environment
- Full Text:
- Authors: Simon, Christian Michael
- Date: 1990
- Subjects: Medical care -- South Africa -- Transkei -- Jotelo , Poor -- Health and hygiene -- South Africa -- Transkei , Transkei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2082 , http://hdl.handle.net/10962/d1001599
- Description: This study aims to characterize and understand the search for health in a rural Transkeian community. It begins with the observation that the people of Jotelo have to negotiate considerable hardships in their daily lives. These hardships include the impact of malnutrition, undernourishment and a wide range of diseases like tuberculosis, typhoid and gastro-enteritis. To survive ill-health, people develop numerous practical strategies. Most significantly, they attempt to maximise availalble resources, like cash, their relations with others and local medical facilities. Hence the study attempts to characterize how and why patients select various kinds of therapy in their search for health. By focusing on patients' recourses to treatment, the study reveals that the search for health is as much a personal experience as it is a social and economic one. This idea is developed in an analysis of the links betw'een work, illness and social reproduction. The point which emerges from this discussion captures the central theme of the study: the search for health is a profoundly personal, social and economic experience. This notion is strengthened by an examination of the historical and contemporary nature of local health and health care. It is observed that health and health care is intimately linked to the local and wider political economy. This not only serves to contextualise the discussion on patients' actual experiences, but points to the fact that these experiences are part of wider processes. By depicting the search for health in this way, the study hopes to have illustrated what people do in times of illness and why. Yet it also claims to have gone beyond such a depiction. By abstracting from its findings, it aims to conclude that the search for health is not merely caused by various local and wider processes, to which it has referred. In other words, it hopes to avoid a deterministic view of patients' experiences in times of distress. Instead, it is argued that the search for health is ultimately an integral part of the local and wider economic and political environment
- Full Text:
Development issues in the Eastern Cape: a review and assessment: proceedings of a symposium organised under the auspices of the Institute of Social and Economic Research at Rhodes University and the Development Society of Southern Africa, held in Port Elizabeth on March 24, 1986
- Rhodes University. Institute of Social and Economic Reseaerch, Development Society of Southern Africa
- Authors: Rhodes University. Institute of Social and Economic Reseaerch , Development Society of Southern Africa
- Date: 1990
- Subjects: Black people -- South Africa -- Cape of Good Hope -- Economic conditions -- Congresses Eastern Cape (South Africa) -- Economic policy -- Congresses
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2340 , vital:20277 , ISBN 0868101400
- Description: Conditions in the Eastern Cape are generally characterised by rising levels of African community frustration and anger and by decreasing levels of economic activity. These, in turn, have led to high and increasing unemployment and to sustained confrontation and conflict as Africans increasingly seek to satisfy legitimate aspirations in a system which has consistently denied them full and free participation in economic and political decision-making. Consumer and school boycotts, work stay-aways and mass protest are the external manifestations of deep-seated grievances because there are no other appropriate forms of community expression. The Eastern Cape has become destabilised by an escalating spiral of violence, repression and reaction, followed by more repression and further violence. Such circumstances are not conducive to sound socio-economic development and it has now become imperative to address the real causes of community antagonism. The symptoms abound and it is these that the authorities have attempted to address, without any significant success. A necessary precondition to addressing local issues is to know what they are and to understand how they affect people's lives. However, such awareness and understanding cannot be secured without communication, discussion and negotiation - and there is no doubt that too little of this takes place in the region. Organised commerce and industry and some local development agencies have made sincere efforts to engage in honest and frank deliberation with the people; but their ability to produce the goods, and to mobilise fundamental change is limited by the constraints of national government policy. In the final analysis, therefore, responsibility for development lies at the national level and a prerequisite for development requires a commitment to change; not just tinkering with the system structure, but a thorough and comprehensive shake-down of that system to introduce a new order. It was against the background of these imperatives that the Institute of Social and Economic Research at Rhodes University and the Development Society of Southern Africa organised a Symposium under the title of "Development Issues in the Eastern Cape: A Review and Assessment" which was held in Port Elizabeth on March 24 1986. The objective of the symposium was twofold: first, to provide a forum at which a range of pertinent development issues could be tentatively explored, and secondly, to provide a platform on which to build a network of on-going communication and negotiation so as to contribute towards intergroup understanding and cooperation, thereby creating an environment in which joint endeavour towards change can be facilitated. The proceedings of the Symposium are contained in this volume, the publication of which represents 'a first step in the process of establishing a forum for local communication, debate and action; a forum designed to establish the economic and political development imperatives for the Eastern Cape and to ensure that these are unequivocally conveyed to government. An essential point of departure for such a forum is that existing and prior policies and strategies have failed and that solutions cannot be found by attempting to remould a structure that is flawed. A new mould must be devised, one that incorporates a totally innovative approach to socio-economic, political and community development in the Eastern Cape. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Authors: Rhodes University. Institute of Social and Economic Reseaerch , Development Society of Southern Africa
- Date: 1990
- Subjects: Black people -- South Africa -- Cape of Good Hope -- Economic conditions -- Congresses Eastern Cape (South Africa) -- Economic policy -- Congresses
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2340 , vital:20277 , ISBN 0868101400
- Description: Conditions in the Eastern Cape are generally characterised by rising levels of African community frustration and anger and by decreasing levels of economic activity. These, in turn, have led to high and increasing unemployment and to sustained confrontation and conflict as Africans increasingly seek to satisfy legitimate aspirations in a system which has consistently denied them full and free participation in economic and political decision-making. Consumer and school boycotts, work stay-aways and mass protest are the external manifestations of deep-seated grievances because there are no other appropriate forms of community expression. The Eastern Cape has become destabilised by an escalating spiral of violence, repression and reaction, followed by more repression and further violence. Such circumstances are not conducive to sound socio-economic development and it has now become imperative to address the real causes of community antagonism. The symptoms abound and it is these that the authorities have attempted to address, without any significant success. A necessary precondition to addressing local issues is to know what they are and to understand how they affect people's lives. However, such awareness and understanding cannot be secured without communication, discussion and negotiation - and there is no doubt that too little of this takes place in the region. Organised commerce and industry and some local development agencies have made sincere efforts to engage in honest and frank deliberation with the people; but their ability to produce the goods, and to mobilise fundamental change is limited by the constraints of national government policy. In the final analysis, therefore, responsibility for development lies at the national level and a prerequisite for development requires a commitment to change; not just tinkering with the system structure, but a thorough and comprehensive shake-down of that system to introduce a new order. It was against the background of these imperatives that the Institute of Social and Economic Research at Rhodes University and the Development Society of Southern Africa organised a Symposium under the title of "Development Issues in the Eastern Cape: A Review and Assessment" which was held in Port Elizabeth on March 24 1986. The objective of the symposium was twofold: first, to provide a forum at which a range of pertinent development issues could be tentatively explored, and secondly, to provide a platform on which to build a network of on-going communication and negotiation so as to contribute towards intergroup understanding and cooperation, thereby creating an environment in which joint endeavour towards change can be facilitated. The proceedings of the Symposium are contained in this volume, the publication of which represents 'a first step in the process of establishing a forum for local communication, debate and action; a forum designed to establish the economic and political development imperatives for the Eastern Cape and to ensure that these are unequivocally conveyed to government. An essential point of departure for such a forum is that existing and prior policies and strategies have failed and that solutions cannot be found by attempting to remould a structure that is flawed. A new mould must be devised, one that incorporates a totally innovative approach to socio-economic, political and community development in the Eastern Cape. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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Die verhouding tussen literêre teorie en kritiek in die Afrikaanse literêre sisteem binne die sg. "nuwe paradigma" aan die hand van gekose figure Marianne de Jong, Joan Hambidge en Gerrit Olivier
- Mudzanani, Nndanduleni Bethuel
- Authors: Mudzanani, Nndanduleni Bethuel
- Date: 1990
- Subjects: Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3599 , http://hdl.handle.net/10962/d1002174 , Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Description: Currently, in the period of Poststructualism literature is widely approached as a cultural and social phenomenon and the aims of literary studies as the illuminating of social codes, ideology etc. embedded in literature. This study evaluates the contribution of specific critics working within the so-called "New paradigm". The concept "New paradigm" is used as an umbrella term covering a number of distinct developments, referring to literature as a system of literary "actions" rather than as a canon of books. In recent years several Afrikaans critics have embraced or adapted current theories in the domains of Deconstruction, Ideology Criticism, Literary, Sociology, Recepticm Aesthetics, Semiotics and Feminism. This study explores and evaluates the application of such theoretical paradigms to their work in the field of practical criticism. This study also explores the relationship between current theories of literature and their antecedents. The notion of current literary theory and practice not only as a broadening of scope and content of the notion of the "literary" but on the other hand as a liberation of theory and practice from an over-deterministic thrust (i.e. the approach of literature as no more than a set of social documents) is also evaluated in this study. A twofold aim of this study can thus be defined: a. to determine the extent to which the shift from the "old" to "new" theories was made necessary by the developing literary and social scene; b. to examine the links beween theory and practice in the work of specific, key figures in Afrikaans. Is it possible for theory and practice to be separated? Is there an important consistence in the relationship between the two in the work of the figures chosen?
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- Authors: Mudzanani, Nndanduleni Bethuel
- Date: 1990
- Subjects: Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3599 , http://hdl.handle.net/10962/d1002174 , Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Description: Currently, in the period of Poststructualism literature is widely approached as a cultural and social phenomenon and the aims of literary studies as the illuminating of social codes, ideology etc. embedded in literature. This study evaluates the contribution of specific critics working within the so-called "New paradigm". The concept "New paradigm" is used as an umbrella term covering a number of distinct developments, referring to literature as a system of literary "actions" rather than as a canon of books. In recent years several Afrikaans critics have embraced or adapted current theories in the domains of Deconstruction, Ideology Criticism, Literary, Sociology, Recepticm Aesthetics, Semiotics and Feminism. This study explores and evaluates the application of such theoretical paradigms to their work in the field of practical criticism. This study also explores the relationship between current theories of literature and their antecedents. The notion of current literary theory and practice not only as a broadening of scope and content of the notion of the "literary" but on the other hand as a liberation of theory and practice from an over-deterministic thrust (i.e. the approach of literature as no more than a set of social documents) is also evaluated in this study. A twofold aim of this study can thus be defined: a. to determine the extent to which the shift from the "old" to "new" theories was made necessary by the developing literary and social scene; b. to examine the links beween theory and practice in the work of specific, key figures in Afrikaans. Is it possible for theory and practice to be separated? Is there an important consistence in the relationship between the two in the work of the figures chosen?
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Enrichment strategies for gifted English first language (HG) pupils at the senior secondary level : a critical evaluation of a programme implemented at Grey Boys' High School, Port Elizabeth, 1986-1988
- Authors: Cunningham, Gregory Mark
- Date: 1990
- Subjects: English language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1510 , http://hdl.handle.net/10962/d1003392
- Description: Programmes developed specifically for the gifted and talented pupil are not a novel idea. Yet, by comparison, the history of gifted education is a brief one. Highly gifted and talented pupils often have difficulty being challenged in a conventional classroom situation. Since classroom instruction is usually designed for the benefit of pupils who function at the level of the majority of their peer age-group, this teaching, no matter how well done, may not be appropriate for the extremely gifted pupil whose abilities differ greatly from this group. Even special programmes for gifted and talented students may be designed for a broad group of gifted students and may not meet the specific needs of the gifted child, especially ones with a special intellectual talent. While it is important to bear aspects such as the characteristics of giftedness and the attributes of the talented individual in mind, the basis of this dissertation examines what enrichment and acceleration strategies may be utilised by the English First Language (HG) teacher when presented with a preselected group of pupils who are gifted in English, utilising a composite gifted educational model as a mechanism for the development of this specific programme.
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- Authors: Cunningham, Gregory Mark
- Date: 1990
- Subjects: English language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1510 , http://hdl.handle.net/10962/d1003392
- Description: Programmes developed specifically for the gifted and talented pupil are not a novel idea. Yet, by comparison, the history of gifted education is a brief one. Highly gifted and talented pupils often have difficulty being challenged in a conventional classroom situation. Since classroom instruction is usually designed for the benefit of pupils who function at the level of the majority of their peer age-group, this teaching, no matter how well done, may not be appropriate for the extremely gifted pupil whose abilities differ greatly from this group. Even special programmes for gifted and talented students may be designed for a broad group of gifted students and may not meet the specific needs of the gifted child, especially ones with a special intellectual talent. While it is important to bear aspects such as the characteristics of giftedness and the attributes of the talented individual in mind, the basis of this dissertation examines what enrichment and acceleration strategies may be utilised by the English First Language (HG) teacher when presented with a preselected group of pupils who are gifted in English, utilising a composite gifted educational model as a mechanism for the development of this specific programme.
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Essential fatty acids and ascorbic acid- interactions and effects on melanoma growth
- Authors: Gardiner, Neil Stockenstrom
- Date: 1990
- Subjects: Fatty acids , Melanoma , Mice -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4549 , http://hdl.handle.net/10962/d1018230
- Description: The present study was carried out to determine the effects and possible mechanisms of action of the essential fatty acids (EFAs) (linoleic acid (LA), gamma-linolenic acid (GLA) and arachidonic acid (AA)) and ascorbic acid (Asc) on BL6 murine melanoma growth in cell culture and in mice. Interactions between the nutrients in influencing melanoma growth as well as possible mechanisms of the interactions were also examined in the above systems. Cell culture studies revealed that all three EFAs (0-SOμg/ml) and Asc (0-200μg/ml) significantly inhibited melanoma growth at the concentrations used. The EF As were also found to significantly inhibit growth, although to a lesser extent than BL6 cells, of monkey kidney (LLCMK) cells which were used as a non-malignant control cell line. Asc in contrast was found not to inhibit growth of these cells. Supplementation of Asc (lOO)μg/ml) to EFA containing (0-50μg/ml) medium was found to significantly increase inhibition of cell growth in both cell lines, and in the BL6 cells in particular, after taking into account the growth inhibitory effects of Asc in the absence of EFAs. The mechanism of cell growth inhibition by the EF As appeared to involve lipid peroxidation but not enhanced prostaglandin (PG) or leukotriene (LT) synthesis. While Asc was found to increase both lipid peroxidation and PG synthesis in the cells, these mechanisms and enhanced LT synthesis did not appear to have played a role in the inhibition of cell growth by Asc or in the growth inhibitory interaction between Asc and the EF As. In vivo studies revealed that diets containing essential or polyunsaturated fatty acids (EFAs/PUFAs) in the form of vegetable oils, and in particular GLA in the form of evening primrose oil, significantly promoted melanoma growth in mice when compared with an EFA/PUFA free diet containing predominantly saturated fats (SF). Supplementary dietary Asc in contrast was found to significantly inhibit melanoma growth in mice fed EFA/PUFA, and in particular GLA, containing diets but not in mice fed SF cont~g diets. This result appears to indicate the occurrence of an interaction between the two nutrients. Ul The mechanism of tumour promotion by the EP As/PUP As did not appear to have involved enhanced PG or LT synthesis or lipid peroxidation. Since dietary EPA/PUPA manipulation was found to significantly alter the EPA content of tissues, including the melanomas, the mechanism of tumour promotion may have involved changes in the EPA composition of the tumour cells. While supplementary Asc was found to significantly increase the Asc content of certain tissues, including the melanomas, which may have played a role in tumour growth inhibition by Asc, it was found not to affect the EPA content of tissues. Enhanced PG or LT synthesis and lipid perox:idation did not appear to have been involved in the tumour growth inhibitory interaction between Asc and the EP As/PUP As. THe activity of the enzyme delta-6-desaturase, a key enzyme in EF A metabolism which catalyses the desaturation of LA to GLA, and the influence of Asc on activity of the enzyme were also examined. The cultured cells, and BL6 cells in particular, were found to contain significant activity of the enzyme. Whereas murine liver microsomal fractions were found to contain delta-6-desaturase activity, microsomes from melanomas grown in mice were found to lack activity of the enzyme. The significant tumour promoting effects of the GLA containing EPO diet may have been the result of the lack of delta-6-desaturase activity in tumour cells grown in mice. Asc was found to stimulate activity of the enzyme in cultured BL6 cells but not in LLCM.K cells, while dietary Asc and EF A/PUP A manipulation did not influence activity of the enzyme in microsomal fractions. This study has confirmed previous reports of the in vivo tumour promoting effects of dietary EP As/PUP As and the tumour growth inhibitory effects of Asc. The in vitro cell growth inhibitory effects of Asc and the EP As also confirm the results of previous reports. Previous studies investigating possible interactions between Asc and EP As/PUP As in influencing tumour cell growth could not be located in the relevant literature. This study may therefore be one of the first investigations of any such interaction between these nutrients in tumour cells. While this study was not able to identify the mechanisms involved in the different tumour promoting or tumour growth inhibitory effects of the two nutrients in the two systems, it did eliminate a number of potential mechanisms. The results of this study also emphasise the difficulty of attempting to compare the results of in vitro and in vivo studies.
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- Authors: Gardiner, Neil Stockenstrom
- Date: 1990
- Subjects: Fatty acids , Melanoma , Mice -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4549 , http://hdl.handle.net/10962/d1018230
- Description: The present study was carried out to determine the effects and possible mechanisms of action of the essential fatty acids (EFAs) (linoleic acid (LA), gamma-linolenic acid (GLA) and arachidonic acid (AA)) and ascorbic acid (Asc) on BL6 murine melanoma growth in cell culture and in mice. Interactions between the nutrients in influencing melanoma growth as well as possible mechanisms of the interactions were also examined in the above systems. Cell culture studies revealed that all three EFAs (0-SOμg/ml) and Asc (0-200μg/ml) significantly inhibited melanoma growth at the concentrations used. The EF As were also found to significantly inhibit growth, although to a lesser extent than BL6 cells, of monkey kidney (LLCMK) cells which were used as a non-malignant control cell line. Asc in contrast was found not to inhibit growth of these cells. Supplementation of Asc (lOO)μg/ml) to EFA containing (0-50μg/ml) medium was found to significantly increase inhibition of cell growth in both cell lines, and in the BL6 cells in particular, after taking into account the growth inhibitory effects of Asc in the absence of EFAs. The mechanism of cell growth inhibition by the EF As appeared to involve lipid peroxidation but not enhanced prostaglandin (PG) or leukotriene (LT) synthesis. While Asc was found to increase both lipid peroxidation and PG synthesis in the cells, these mechanisms and enhanced LT synthesis did not appear to have played a role in the inhibition of cell growth by Asc or in the growth inhibitory interaction between Asc and the EF As. In vivo studies revealed that diets containing essential or polyunsaturated fatty acids (EFAs/PUFAs) in the form of vegetable oils, and in particular GLA in the form of evening primrose oil, significantly promoted melanoma growth in mice when compared with an EFA/PUFA free diet containing predominantly saturated fats (SF). Supplementary dietary Asc in contrast was found to significantly inhibit melanoma growth in mice fed EFA/PUFA, and in particular GLA, containing diets but not in mice fed SF cont~g diets. This result appears to indicate the occurrence of an interaction between the two nutrients. Ul The mechanism of tumour promotion by the EP As/PUP As did not appear to have involved enhanced PG or LT synthesis or lipid peroxidation. Since dietary EPA/PUPA manipulation was found to significantly alter the EPA content of tissues, including the melanomas, the mechanism of tumour promotion may have involved changes in the EPA composition of the tumour cells. While supplementary Asc was found to significantly increase the Asc content of certain tissues, including the melanomas, which may have played a role in tumour growth inhibition by Asc, it was found not to affect the EPA content of tissues. Enhanced PG or LT synthesis and lipid perox:idation did not appear to have been involved in the tumour growth inhibitory interaction between Asc and the EP As/PUP As. THe activity of the enzyme delta-6-desaturase, a key enzyme in EF A metabolism which catalyses the desaturation of LA to GLA, and the influence of Asc on activity of the enzyme were also examined. The cultured cells, and BL6 cells in particular, were found to contain significant activity of the enzyme. Whereas murine liver microsomal fractions were found to contain delta-6-desaturase activity, microsomes from melanomas grown in mice were found to lack activity of the enzyme. The significant tumour promoting effects of the GLA containing EPO diet may have been the result of the lack of delta-6-desaturase activity in tumour cells grown in mice. Asc was found to stimulate activity of the enzyme in cultured BL6 cells but not in LLCM.K cells, while dietary Asc and EF A/PUP A manipulation did not influence activity of the enzyme in microsomal fractions. This study has confirmed previous reports of the in vivo tumour promoting effects of dietary EP As/PUP As and the tumour growth inhibitory effects of Asc. The in vitro cell growth inhibitory effects of Asc and the EP As also confirm the results of previous reports. Previous studies investigating possible interactions between Asc and EP As/PUP As in influencing tumour cell growth could not be located in the relevant literature. This study may therefore be one of the first investigations of any such interaction between these nutrients in tumour cells. While this study was not able to identify the mechanisms involved in the different tumour promoting or tumour growth inhibitory effects of the two nutrients in the two systems, it did eliminate a number of potential mechanisms. The results of this study also emphasise the difficulty of attempting to compare the results of in vitro and in vivo studies.
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