Differentiated Instruction: A Study of English Second Language Teachers’ Awareness and Implementation in Selected High Schools in the Eastern Cape Province
- Authors: Ndu, Onyinyechi Glory
- Date: 2019
- Subjects: English language -- Study and teaching Language and languages -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , D Lit. (English)
- Identifier: http://hdl.handle.net/10353/11440 , vital:39072
- Description: The lack of visible academic excellence in South Africa has necessitated the search for a more in-depth approach in teaching and learning. The Department of Basic Education, school administrators and School Governing Bodies are not left out in the search for a distinct approach that would be able to assist teachers and also accommodate diverse learning abilities found in the classroom. The purpose of this study is to investigate English Second Language teachers’ awareness and implementation of differentiated instruction in selected high schools in the Eastern Cape Province, South Africa. The objectives were to find out the extent to which teachers adopt differentiated instructions in their classes: to examine teachers’ narratives about differentiated instruction and the alternative instruction teachers’ use in their classrooms. The study was anchored on the socio-cultural theory, multiple intelligence theory and learning style theory. It employed a mixed method research and triangulation, which was very beneficial for the validation of the research findings. It followed a case study exploratory design and descriptive survey design. A purposive sample of hundred and six (106) participants were used in the study. The quantitative data were analysed using tables, frequencies and percentages while the qualitative data were analysed thematically. The findings of the study revealed that ESL Grade 10 high school teachers were not aware of the term “Differentiated Instruction” even though to some extent they adopted DI approach. Teachers had mixed narratives about DI implementation and they used different alternative instructions during their lessons. The researcher recommended that teachers should be introduced to DI approach and be given more assistance, motivation, exposure and trainings in the form of conferences and seminars on proper DI implementation. Also teachers should be encouraged to continuously develop themselves academically in order to adjust to the new trend of managing the diverse learners that exist in their classes and in differentiating instruction with technology.
- Full Text:
- Date Issued: 2019
- Authors: Ndu, Onyinyechi Glory
- Date: 2019
- Subjects: English language -- Study and teaching Language and languages -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , D Lit. (English)
- Identifier: http://hdl.handle.net/10353/11440 , vital:39072
- Description: The lack of visible academic excellence in South Africa has necessitated the search for a more in-depth approach in teaching and learning. The Department of Basic Education, school administrators and School Governing Bodies are not left out in the search for a distinct approach that would be able to assist teachers and also accommodate diverse learning abilities found in the classroom. The purpose of this study is to investigate English Second Language teachers’ awareness and implementation of differentiated instruction in selected high schools in the Eastern Cape Province, South Africa. The objectives were to find out the extent to which teachers adopt differentiated instructions in their classes: to examine teachers’ narratives about differentiated instruction and the alternative instruction teachers’ use in their classrooms. The study was anchored on the socio-cultural theory, multiple intelligence theory and learning style theory. It employed a mixed method research and triangulation, which was very beneficial for the validation of the research findings. It followed a case study exploratory design and descriptive survey design. A purposive sample of hundred and six (106) participants were used in the study. The quantitative data were analysed using tables, frequencies and percentages while the qualitative data were analysed thematically. The findings of the study revealed that ESL Grade 10 high school teachers were not aware of the term “Differentiated Instruction” even though to some extent they adopted DI approach. Teachers had mixed narratives about DI implementation and they used different alternative instructions during their lessons. The researcher recommended that teachers should be introduced to DI approach and be given more assistance, motivation, exposure and trainings in the form of conferences and seminars on proper DI implementation. Also teachers should be encouraged to continuously develop themselves academically in order to adjust to the new trend of managing the diverse learners that exist in their classes and in differentiating instruction with technology.
- Full Text:
- Date Issued: 2019
A critical evaluation of the human skin blanching assay and comparative bioavailability studies on topical corticosteroid preparations
- Authors: Meyer, Eric
- Date: 1989
- Subjects: Dermatopharmacology Skin, Effect of drugs on Adrenocortical hormones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3727 , http://hdl.handle.net/10962/d1001464
- Description: Several aspects of the human skin blanching assay were evaluated in an attempt to suggest improvements in the methodology of this assay. Three trials were performed in the unoccluded application mode, using two proprietary creams containing 0,1% betamethasone (as the 17-valerate). Preliminary observations of the influence of ambient temperature and relative humidity on the blanching response did not allow definite conclusions to be drawn. Studies on the number of observers required for reliable results of comparative blanching indicated that at least two trained observers should be employed. Analyses of the results of individual volunteers demonstrated the expected biological variability, and suggest that subjects selected for trials should represent a range of blanching responses. No sex-related differences in blanching responses were found, and both arms exhibited similar sensitivity to corticosteroids. Retrospective analysis of 95 040 observations of blanching responses showed that in the unoccluded application mode blanching is lowest close to the wrist, and in the occluded mode blanching is lowest close to the elbow. Studies on the method of transportation of Betnovate preparations suggest that topical formulations should not be exposed to temperature extremes during transportation. It is proposed that patients should not transport topical formulations in the holds of ships or aircraft, and that exporters and manufacturers should make use of special transportation and storage conditions. In a study of ten topical formulations from three countries it was found that there was no trend of products from one country consistently exhibiting superior blanching to products from the other two countries, or products from one country consistently exhibiting the lowest degree of blanching, although considerable differences in blanching responses were found in some cases. Interpretation of the results of these studies demonstrated the importance of employing a combination of statistical analyses, blanching profiles and AUC values when drawing conclusions regarding comparative bioavailability. A study of the blanching profiles of Betnovate cream included in all 16 trials performed during this work indicated that this preparation behaved in a similar fashion during all trials, thereby giving credence to the results of the trials
- Full Text:
- Date Issued: 1989
- Authors: Meyer, Eric
- Date: 1989
- Subjects: Dermatopharmacology Skin, Effect of drugs on Adrenocortical hormones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3727 , http://hdl.handle.net/10962/d1001464
- Description: Several aspects of the human skin blanching assay were evaluated in an attempt to suggest improvements in the methodology of this assay. Three trials were performed in the unoccluded application mode, using two proprietary creams containing 0,1% betamethasone (as the 17-valerate). Preliminary observations of the influence of ambient temperature and relative humidity on the blanching response did not allow definite conclusions to be drawn. Studies on the number of observers required for reliable results of comparative blanching indicated that at least two trained observers should be employed. Analyses of the results of individual volunteers demonstrated the expected biological variability, and suggest that subjects selected for trials should represent a range of blanching responses. No sex-related differences in blanching responses were found, and both arms exhibited similar sensitivity to corticosteroids. Retrospective analysis of 95 040 observations of blanching responses showed that in the unoccluded application mode blanching is lowest close to the wrist, and in the occluded mode blanching is lowest close to the elbow. Studies on the method of transportation of Betnovate preparations suggest that topical formulations should not be exposed to temperature extremes during transportation. It is proposed that patients should not transport topical formulations in the holds of ships or aircraft, and that exporters and manufacturers should make use of special transportation and storage conditions. In a study of ten topical formulations from three countries it was found that there was no trend of products from one country consistently exhibiting superior blanching to products from the other two countries, or products from one country consistently exhibiting the lowest degree of blanching, although considerable differences in blanching responses were found in some cases. Interpretation of the results of these studies demonstrated the importance of employing a combination of statistical analyses, blanching profiles and AUC values when drawing conclusions regarding comparative bioavailability. A study of the blanching profiles of Betnovate cream included in all 16 trials performed during this work indicated that this preparation behaved in a similar fashion during all trials, thereby giving credence to the results of the trials
- Full Text:
- Date Issued: 1989
Strategies used by teachers to promote reading in grade 4 : a case of english first additional language learners
- Authors: Fesi, Liziwe
- Date: 2018
- Subjects: English language -- Study and teaching English language -- Rhetoric Reading -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9264 , vital:34316
- Description: The study examines strategies used by teachers to promote reading: A Case of English First Additional Language Learners. The study was located within the constructivism paradigm of reading and used a qualitative research approach that incorporated a case study research design in the collection, analysis and interpretation of the data. The data instruments used were interviews and observations. Data were analyzed using non-statistical procedures. The findings of the study revealed that reading problems are still eminent in Grade Four. It was found that the resources in schools inhibits the progress to promote reading. The educational system is underdeveloped and under resourced with respect to reading materials, and schools are in a bad state due to obsolete facilities. Inadequate infrastructure is also another challenge since most of the participants reported that classes are overcrowded; thus, limiting the space to interact with learners. It was found that primary schools have no libraries; as a result, it was difficult for the teachers to instill the culture of reading. Some participants revealed that technology can be useful to encourage reading, however, their schools have no computer centers and most teachers do not know how to use computers. It emerged from the findings that parents fail to involve themselves in their children’s education. In addition, it was found that poor socio-economic backgrounds affect many homes, and this has a negative impact on schools. Most South African parents are found to be unable to support their children at all. There are also challenges interconnected with the English First Additional Language learners, the eccentricities of the English language, the teacher training and continuing professional development of teachers, as it emerged from the findings of this study that most teachers do not understand the reading strategies, skills of teaching reading and learners lack vocabulary, hence their resistance to reading. A comprehensive model of strategies to improve reading in primary schools was developed by the researcher based on the findings of the study and an extensive literature review.
- Full Text:
- Date Issued: 2018
- Authors: Fesi, Liziwe
- Date: 2018
- Subjects: English language -- Study and teaching English language -- Rhetoric Reading -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9264 , vital:34316
- Description: The study examines strategies used by teachers to promote reading: A Case of English First Additional Language Learners. The study was located within the constructivism paradigm of reading and used a qualitative research approach that incorporated a case study research design in the collection, analysis and interpretation of the data. The data instruments used were interviews and observations. Data were analyzed using non-statistical procedures. The findings of the study revealed that reading problems are still eminent in Grade Four. It was found that the resources in schools inhibits the progress to promote reading. The educational system is underdeveloped and under resourced with respect to reading materials, and schools are in a bad state due to obsolete facilities. Inadequate infrastructure is also another challenge since most of the participants reported that classes are overcrowded; thus, limiting the space to interact with learners. It was found that primary schools have no libraries; as a result, it was difficult for the teachers to instill the culture of reading. Some participants revealed that technology can be useful to encourage reading, however, their schools have no computer centers and most teachers do not know how to use computers. It emerged from the findings that parents fail to involve themselves in their children’s education. In addition, it was found that poor socio-economic backgrounds affect many homes, and this has a negative impact on schools. Most South African parents are found to be unable to support their children at all. There are also challenges interconnected with the English First Additional Language learners, the eccentricities of the English language, the teacher training and continuing professional development of teachers, as it emerged from the findings of this study that most teachers do not understand the reading strategies, skills of teaching reading and learners lack vocabulary, hence their resistance to reading. A comprehensive model of strategies to improve reading in primary schools was developed by the researcher based on the findings of the study and an extensive literature review.
- Full Text:
- Date Issued: 2018
The frontier in South African English verse : 1820-1927
- Authors: Taylor, Avis Elizabeth
- Date: 1960
- Subjects: South African poetry (English) -- 19th century , South African literature (English) -- History and criticism , South Africa -- In literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2318 , http://hdl.handle.net/10962/d1013347
- Description: The concept of a distinctively South African poetry in English has been, and still is, derided as a "pipe dream" as part of the fallacy which stems from the desire for a "national" literature. In 1955, for instance, C.J. Harvey (in an article containing much common sense as well as sound literary judgment) denounced the self-conscious hunting for "Local Colour" which engrosses so many South African writers. Harvey claimed: "Our civilization is not "South African", except in trivial details, it is Western European, and more specifically as far as poetry written in English is concerned, English ... ". There is a serious error of emphasis here. It would be more accurate to say that our ancestors brought Western European civilization to this continent. To imagine that this civilisation has not undergone and is not still constantly suffering a subtle but far-reaching metamorphosis in Africa would be to fly in the face of reality. White South Africans do not only carry the same identity-card but they can be distinguished from Frenchmen, Englishmen or Irishmen by more than "trivial details". This thesis is an examination of some af the earliest English written in southern Africa, particularly of the verse produced by our poetasters and near-poets. It attempts, during the course of this examination, to call attention to a few of the more significant changes which have arisen as the result of the importation of Western civilsation to an African frontier. Further I hope to show some at the varying ways in which these differences affected the white pioneer and how this has been reflected in our verse since pioneering times. In this sense the Frontier may be thought of as the background against which South African English writers developed certain characteristic traits. Intro., p. 1-2.
- Full Text:
- Date Issued: 1960
- Authors: Taylor, Avis Elizabeth
- Date: 1960
- Subjects: South African poetry (English) -- 19th century , South African literature (English) -- History and criticism , South Africa -- In literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2318 , http://hdl.handle.net/10962/d1013347
- Description: The concept of a distinctively South African poetry in English has been, and still is, derided as a "pipe dream" as part of the fallacy which stems from the desire for a "national" literature. In 1955, for instance, C.J. Harvey (in an article containing much common sense as well as sound literary judgment) denounced the self-conscious hunting for "Local Colour" which engrosses so many South African writers. Harvey claimed: "Our civilization is not "South African", except in trivial details, it is Western European, and more specifically as far as poetry written in English is concerned, English ... ". There is a serious error of emphasis here. It would be more accurate to say that our ancestors brought Western European civilization to this continent. To imagine that this civilisation has not undergone and is not still constantly suffering a subtle but far-reaching metamorphosis in Africa would be to fly in the face of reality. White South Africans do not only carry the same identity-card but they can be distinguished from Frenchmen, Englishmen or Irishmen by more than "trivial details". This thesis is an examination of some af the earliest English written in southern Africa, particularly of the verse produced by our poetasters and near-poets. It attempts, during the course of this examination, to call attention to a few of the more significant changes which have arisen as the result of the importation of Western civilsation to an African frontier. Further I hope to show some at the varying ways in which these differences affected the white pioneer and how this has been reflected in our verse since pioneering times. In this sense the Frontier may be thought of as the background against which South African English writers developed certain characteristic traits. Intro., p. 1-2.
- Full Text:
- Date Issued: 1960
The effects of a gradual shift rotation and a split shift nap intervention on cognitive, physiological and subjective responses under simulated night shift settings
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
Application of CE, HPLC and LC-MS-MS for the analysis and quality control of Ginkgo biloba dosage forms
- Authors: Dubber, Mary-Jean
- Date: 2006
- Subjects: Pharmaceutical chemistry -- Quality control Ginkgo Micelles Capillary electrophoresis High performance liquid chromatography Drugs -- Dosage forms Flavonoids Terpenes Herbals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3757 , http://hdl.handle.net/10962/d1003235
- Description: Natural products are complex mixtures of compounds with therapeutic effects which are often reported to be due to the synergistic action of multiple and sometimes unknown components. Consequently, standardization of these products is complex and a lack of effective quality control (QC) criteria in most countries has led to marketing of commercial products with questionable quality, safety and efficacy (QSE). The aim of this study was therefore to develop qualitative and quantitative analytical methods for use in the QC of Ginkgo biloba solid oral dosage forms. Initially, a micellar electrokinetic chromatography (MEKC) method was developed for the identification of the flavonol glycosides, rutin and quercitrin as well as 3 flavonol aglycones, quercetin, kaempferol and isorhamnetin in crude extracts of 4 Ginkgo biloba solid oral dosage forms using ultraviolet (UV) detection. A reversed-flow cyclodextrin-modified MEKC method was subsequently developed for the simultaneous determination of the aforementioned flavonols as well as ginkgolide A, B, C, J and bilobalide (all positive markers) in Ginkgo commercial products. A non-aqueous capillary electrophoresis (CE) method was also developed for fingerprinting the presence of ginkgolic acids (negative markers) in Ginkgo biloba leaf extracts, which are purported to be associated with toxic properties. This method was also applied to 2 Ginkgo biloba commercial products. Since the flavonols have strong UV absorbing chromophores, a reversed phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated using photo-diode-array (PDA) detection which was then successfully applied to fingerprint commercially available Ginkgo biloba solid oral dosage forms as well as quantify the relevant flavonol markers present in these extracts. Sample preparation was simple, rapid and cost efficient with minimal clean-up and the employment of a minibore column which requires low mobile phase flow rates contributed to the economy of the method. Unlike the conventional QC approach, samples were not hydrolyzed and direct determination of 2 intact flavonol glycosides, together with the usual aglycone markers was facilitated which provided maximal content information for fingerprint comparisons. On the other hand, terpene trilactones possess poor chromophores and an alternative detection method to UV was required in order to obtain suitable sensitivity. RP-HPLC with evaporative light scattering detection (ELSD) was selected for quantification of these non-volatile constituents in Ginkgo dosage forms and this method was deemed suitable for the routine QC analysis of these positive markers in commercial products. Since approximately 33 flavonoids have been identified in Ginkgo biloba leaf extracts, baseline separation using UV/PDA detection normally requires complex gradient programs and long analysis times. In addition, unequivocal identification of the flavonoids with similar UV spectra and elution times cannot be guaranteed. A liquid chromatographic tandem mass spectrometric (LC-MS-MS) method was therefore developed and validated in order to ensure accurate quantification of the selected flavonol marker compounds in Ginkgo commercial products. LC-MS-MS analysis of Ginkgo extracts revealed, in addition to rutin, the possible presence of other quercetin analogues, quercetin-3-Orhamnoside-7-O-glucoside or quercetin-3-O-glucoside-7-O-rhamnoside, previously unreported in Ginkgo biloba leaf extracts or dosage forms. In terms of evaluating the most suitable analytical method for QC, CE shows exceptional potential in the future analysis of Ginkgo biloba dosage forms while HPLC-PDA and HPLC-ELSD are currently the most affordable and practical instruments for the routine analysis of the flavonols and terpenoids, respectively. LC-MS-MS proved to be pivotal for the accurate identification and quantification of the flavonols due to interference by other flavonoid compounds with similar retention times and UV spectra to the peaks of interest. All quantitative and qualitative results revealed large discrepancies in the marker content between the products regardless of which batch was analysed and product labels disclosed little relevant information. Although currently not required by most regulatory agencies, some of the usual quality criteria applied to orthodox medicines was evaluated. In particular, dissolution analysis, disintegration, tablet hardness and weight uniformity were assessed and revealed similar inconsistencies. This thesis emphasises that implementation of effective QC criteria is long overdue and is essential to ensure consistent product QSE of commercially available Ginkgo biloba solid oral dosage forms.
- Full Text:
- Date Issued: 2006
- Authors: Dubber, Mary-Jean
- Date: 2006
- Subjects: Pharmaceutical chemistry -- Quality control Ginkgo Micelles Capillary electrophoresis High performance liquid chromatography Drugs -- Dosage forms Flavonoids Terpenes Herbals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3757 , http://hdl.handle.net/10962/d1003235
- Description: Natural products are complex mixtures of compounds with therapeutic effects which are often reported to be due to the synergistic action of multiple and sometimes unknown components. Consequently, standardization of these products is complex and a lack of effective quality control (QC) criteria in most countries has led to marketing of commercial products with questionable quality, safety and efficacy (QSE). The aim of this study was therefore to develop qualitative and quantitative analytical methods for use in the QC of Ginkgo biloba solid oral dosage forms. Initially, a micellar electrokinetic chromatography (MEKC) method was developed for the identification of the flavonol glycosides, rutin and quercitrin as well as 3 flavonol aglycones, quercetin, kaempferol and isorhamnetin in crude extracts of 4 Ginkgo biloba solid oral dosage forms using ultraviolet (UV) detection. A reversed-flow cyclodextrin-modified MEKC method was subsequently developed for the simultaneous determination of the aforementioned flavonols as well as ginkgolide A, B, C, J and bilobalide (all positive markers) in Ginkgo commercial products. A non-aqueous capillary electrophoresis (CE) method was also developed for fingerprinting the presence of ginkgolic acids (negative markers) in Ginkgo biloba leaf extracts, which are purported to be associated with toxic properties. This method was also applied to 2 Ginkgo biloba commercial products. Since the flavonols have strong UV absorbing chromophores, a reversed phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated using photo-diode-array (PDA) detection which was then successfully applied to fingerprint commercially available Ginkgo biloba solid oral dosage forms as well as quantify the relevant flavonol markers present in these extracts. Sample preparation was simple, rapid and cost efficient with minimal clean-up and the employment of a minibore column which requires low mobile phase flow rates contributed to the economy of the method. Unlike the conventional QC approach, samples were not hydrolyzed and direct determination of 2 intact flavonol glycosides, together with the usual aglycone markers was facilitated which provided maximal content information for fingerprint comparisons. On the other hand, terpene trilactones possess poor chromophores and an alternative detection method to UV was required in order to obtain suitable sensitivity. RP-HPLC with evaporative light scattering detection (ELSD) was selected for quantification of these non-volatile constituents in Ginkgo dosage forms and this method was deemed suitable for the routine QC analysis of these positive markers in commercial products. Since approximately 33 flavonoids have been identified in Ginkgo biloba leaf extracts, baseline separation using UV/PDA detection normally requires complex gradient programs and long analysis times. In addition, unequivocal identification of the flavonoids with similar UV spectra and elution times cannot be guaranteed. A liquid chromatographic tandem mass spectrometric (LC-MS-MS) method was therefore developed and validated in order to ensure accurate quantification of the selected flavonol marker compounds in Ginkgo commercial products. LC-MS-MS analysis of Ginkgo extracts revealed, in addition to rutin, the possible presence of other quercetin analogues, quercetin-3-Orhamnoside-7-O-glucoside or quercetin-3-O-glucoside-7-O-rhamnoside, previously unreported in Ginkgo biloba leaf extracts or dosage forms. In terms of evaluating the most suitable analytical method for QC, CE shows exceptional potential in the future analysis of Ginkgo biloba dosage forms while HPLC-PDA and HPLC-ELSD are currently the most affordable and practical instruments for the routine analysis of the flavonols and terpenoids, respectively. LC-MS-MS proved to be pivotal for the accurate identification and quantification of the flavonols due to interference by other flavonoid compounds with similar retention times and UV spectra to the peaks of interest. All quantitative and qualitative results revealed large discrepancies in the marker content between the products regardless of which batch was analysed and product labels disclosed little relevant information. Although currently not required by most regulatory agencies, some of the usual quality criteria applied to orthodox medicines was evaluated. In particular, dissolution analysis, disintegration, tablet hardness and weight uniformity were assessed and revealed similar inconsistencies. This thesis emphasises that implementation of effective QC criteria is long overdue and is essential to ensure consistent product QSE of commercially available Ginkgo biloba solid oral dosage forms.
- Full Text:
- Date Issued: 2006
An analysis of the basic needs approach in its application to regional economic development with specific reference to Ciske
- Authors: Keeton, Gavin Rodney
- Date: 1984
- Subjects: Basic needs -- South Africa -- Ciskei Ciskei (South Africa) -- Economic conditions Ciskei (South Africa) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1037 , http://hdl.handle.net/10962/d1004566
- Description: In Chapter 7, it was argued that improved satisfaction of basic needs could in principle lead to increased labour productivity and, via a comulative process, to increased output and income levels. Higher incomes could in turn mean further improved satisfaction of basic needs, greater labour productivity and even greater output and income levels. Thus the satisfaction of basic needs could be seen as a means towards the end of improved living standards and the reduction of poverty, and hence an instrument of development policy. From the analysis of basic needs in Ciskei, it is apparent that government expenditure has been such that the "core" basic needs have evidently been catered for, at least to some extent, for some time. Yet, there has been nothing like a concerted strategy, and expenditure on basic needs was the result of ad hoc measures, rather than a conscious strategy or development policy as such. Basic needs were therefore seen simply as ends in themselves, rather than as means to the end of self-sustained economic development. In the case of Ciskei, more information about the satisfaction of basic needs, especially health, and water supply and sanitation, is required at the present stage. Such information should not only be seen in quantitative terms (as "inputs"), but also be evaluated qualitatively (as "outputs"). In other words, basic needs should be viewed functionally as thresholds to the goal of self-sustained economic development. This applies particularly to educatfon, where the total supply may be misleading, more significant measures being quality, access and actual consumption. Data for health, and water supply and sanitation, are not readily available, and again should reflect access and usage as well as availability. Nutritional data should not only reveal the extent and nature of poor nutrition (malnutrition) but also its causes, such as, inadequate expenditure on food on account of low income levels, or inappropriate nutritional patterns of consumption. Data on shelter should take into account the appropriateness of standards and types of shelter, rather than simply the number of houses as such. At the same time, the extent to which basic needs are complementary should be investigated; e.g. the effect the improved satisfaction of education would have on shelter, shelter on health, etc. The stronger such complementarities, the lower total government expenditure on basic needs would have to be. Similarly, if expenditure on basic needs is inappropriate or ill-directed, a revision of standards and redirection of resources may be necessary. In the case of Ciskei, it may well be that total expenditure on basic needs may not be inadequate as such at the present stage, but rather that co-ordination of existing expenditure is required to yield a purposive development policy. A powerful case for the suitability of a Basic Needs strategy for Ciskei may be suggested by the intermediate nature of economic development within its borders. To the extent that some basic needs are already satisfied, at least to some degree and some more than others, certain preconditions for economic development can be said to already exist. Yet it cannot be claimed that Ciskei has reached the "take-off" stage into self-sustained economic growth in the Rostovian sense. Nevertheless, a deliberately co-ordinated Basic Needs strategy may well move Ciskei away from the danger of slipping back into the so-called "Low-Level Equilibrium Trap." In other words, a more scientifically designed, co-ordinated and deliberately applied strategy, whereby basic needs become the means towards self-sustained economic growth, should at least be able to establish the "preconditions for take-off" necessary for sustained economic development.
- Full Text:
- Date Issued: 1984
- Authors: Keeton, Gavin Rodney
- Date: 1984
- Subjects: Basic needs -- South Africa -- Ciskei Ciskei (South Africa) -- Economic conditions Ciskei (South Africa) -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1037 , http://hdl.handle.net/10962/d1004566
- Description: In Chapter 7, it was argued that improved satisfaction of basic needs could in principle lead to increased labour productivity and, via a comulative process, to increased output and income levels. Higher incomes could in turn mean further improved satisfaction of basic needs, greater labour productivity and even greater output and income levels. Thus the satisfaction of basic needs could be seen as a means towards the end of improved living standards and the reduction of poverty, and hence an instrument of development policy. From the analysis of basic needs in Ciskei, it is apparent that government expenditure has been such that the "core" basic needs have evidently been catered for, at least to some extent, for some time. Yet, there has been nothing like a concerted strategy, and expenditure on basic needs was the result of ad hoc measures, rather than a conscious strategy or development policy as such. Basic needs were therefore seen simply as ends in themselves, rather than as means to the end of self-sustained economic development. In the case of Ciskei, more information about the satisfaction of basic needs, especially health, and water supply and sanitation, is required at the present stage. Such information should not only be seen in quantitative terms (as "inputs"), but also be evaluated qualitatively (as "outputs"). In other words, basic needs should be viewed functionally as thresholds to the goal of self-sustained economic development. This applies particularly to educatfon, where the total supply may be misleading, more significant measures being quality, access and actual consumption. Data for health, and water supply and sanitation, are not readily available, and again should reflect access and usage as well as availability. Nutritional data should not only reveal the extent and nature of poor nutrition (malnutrition) but also its causes, such as, inadequate expenditure on food on account of low income levels, or inappropriate nutritional patterns of consumption. Data on shelter should take into account the appropriateness of standards and types of shelter, rather than simply the number of houses as such. At the same time, the extent to which basic needs are complementary should be investigated; e.g. the effect the improved satisfaction of education would have on shelter, shelter on health, etc. The stronger such complementarities, the lower total government expenditure on basic needs would have to be. Similarly, if expenditure on basic needs is inappropriate or ill-directed, a revision of standards and redirection of resources may be necessary. In the case of Ciskei, it may well be that total expenditure on basic needs may not be inadequate as such at the present stage, but rather that co-ordination of existing expenditure is required to yield a purposive development policy. A powerful case for the suitability of a Basic Needs strategy for Ciskei may be suggested by the intermediate nature of economic development within its borders. To the extent that some basic needs are already satisfied, at least to some degree and some more than others, certain preconditions for economic development can be said to already exist. Yet it cannot be claimed that Ciskei has reached the "take-off" stage into self-sustained economic growth in the Rostovian sense. Nevertheless, a deliberately co-ordinated Basic Needs strategy may well move Ciskei away from the danger of slipping back into the so-called "Low-Level Equilibrium Trap." In other words, a more scientifically designed, co-ordinated and deliberately applied strategy, whereby basic needs become the means towards self-sustained economic growth, should at least be able to establish the "preconditions for take-off" necessary for sustained economic development.
- Full Text:
- Date Issued: 1984
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