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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation and validation of in vitro assays to determine cell viability for HIV/AIDS expermentation with Pheroid TM technology / Helanie van der Merwe.

Van der Merwe, Helanie January 2008 (has links)
The Southern parts of Africa have the highest prevalence of HIV-infected people and South Africa is the country with the highest number of infections in the world. There is still no cure for AIDS, but anti-HIV medicine can prolong and enhance the quality of life of an HIV infected person. Patient adherence with antiretroviral therapy is extremely low due to difficult dosing intervals, problematic dosage forms, instability of the antiretrovirals (ARVs) and the severe side-effects caused by these drugs; this leads to resistance of HIV to these drugs. Pheroid™ technology is a patented delivery system. Pheroid™ vesicles were used during this study. The entrapment of an active within the Pheroid™ would generally provide a safer, more effective formulation than the active alone. This could mean that the amount of drug needed for treatment of HIV can be decreased while producing fewer adverse effects and reducing the price of treatment. The main objectives of this study were to optimise and validate the cell viability and viral replication assays that can be used in an in vitro viral infection model. The MTT assay was used to asses the viability of the cells and to determine the toxicity of the antiretroviral drugs and Pheroid™ on the cells. HIV-1 assays were evaluated and used to determine the viral replication in the cells. Two different continuous cell lines were chosen for this study, an anchorage dependent GHOST cell line and suspended M7-Luc cells. Both these cell lines were best infected with the SWl virus. SWl is a subtype C, CXCR4 utilising virus. Subtype C is responsible for 60 % of the HIV infections worldwide and is the prevalent subtype in SUb-Saharan Africa .. Infection enhancers were not added to the cells to improve viral infection since it was observed that the Pheroid™ in combination with DEAE-dextran or Polybrene caused cytotoxicity probably by disrupting the cell's membrane. Antioxidants were added to the Pheroid ™ formulation since it was observed that the viability of the cells incubated with the Pheroid™ decreased as the Pheroid ™ matured. The added antioxidants had no significant effect on the cells. Abacavir (ABC) was chosen as the test substance for this study since it showed low cytotoxicity in cell cultures and is water soluble and would not present solubility issues in the media. It was entrapped within the Pheroid™ and its in vitro efficacy and toxicity was tested on HIV-infected and uninfected cell cultures. One directlHIV-specific (p24 antigen ELISA assay) and one indirect (Luciferase) assays were used to asses the inhibition of HIV replication caused by ABC. The p24 antigen ELISA (Enzyme-Linked ImmunoSorbent Assay) assay required a lot of washing steps and were rather expensive to use. The Luciferase assay was only used on the M7-Luc cells; this assay was sensitive, inexpensive and easy to use. The MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) viability assay was used to measure the toxicity caused by the Pheroid ™ and/or ABC on the cells. MTT is a widely used quantitative colorimetric assay to measure the viability of cells. The vitamin E and antioxidants contained in the Pheroid ™ reduced the MTT and produced results that were misinterpreted as enhanced viability when the Pheroid™ was present during MTT analysis. To prevent this problem an additional washing step should be introduced prior to analysis to reduce the interference of the Pheroid ™ with analytical methods. In conclusion, the efficacy of ABC entrapped within the Pheroid™ is still inconclusive and further studies will have to be done. MTT should be used with care for viability analysis of cells incubated in the presence of Pheroid TM. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.
2

Evaluation and validation of in vitro assays to determine cell viability for HIV/AIDS expermentation with Pheroid TM technology / Helanie van der Merwe.

Van der Merwe, Helanie January 2008 (has links)
The Southern parts of Africa have the highest prevalence of HIV-infected people and South Africa is the country with the highest number of infections in the world. There is still no cure for AIDS, but anti-HIV medicine can prolong and enhance the quality of life of an HIV infected person. Patient adherence with antiretroviral therapy is extremely low due to difficult dosing intervals, problematic dosage forms, instability of the antiretrovirals (ARVs) and the severe side-effects caused by these drugs; this leads to resistance of HIV to these drugs. Pheroid™ technology is a patented delivery system. Pheroid™ vesicles were used during this study. The entrapment of an active within the Pheroid™ would generally provide a safer, more effective formulation than the active alone. This could mean that the amount of drug needed for treatment of HIV can be decreased while producing fewer adverse effects and reducing the price of treatment. The main objectives of this study were to optimise and validate the cell viability and viral replication assays that can be used in an in vitro viral infection model. The MTT assay was used to asses the viability of the cells and to determine the toxicity of the antiretroviral drugs and Pheroid™ on the cells. HIV-1 assays were evaluated and used to determine the viral replication in the cells. Two different continuous cell lines were chosen for this study, an anchorage dependent GHOST cell line and suspended M7-Luc cells. Both these cell lines were best infected with the SWl virus. SWl is a subtype C, CXCR4 utilising virus. Subtype C is responsible for 60 % of the HIV infections worldwide and is the prevalent subtype in SUb-Saharan Africa .. Infection enhancers were not added to the cells to improve viral infection since it was observed that the Pheroid™ in combination with DEAE-dextran or Polybrene caused cytotoxicity probably by disrupting the cell's membrane. Antioxidants were added to the Pheroid ™ formulation since it was observed that the viability of the cells incubated with the Pheroid™ decreased as the Pheroid ™ matured. The added antioxidants had no significant effect on the cells. Abacavir (ABC) was chosen as the test substance for this study since it showed low cytotoxicity in cell cultures and is water soluble and would not present solubility issues in the media. It was entrapped within the Pheroid™ and its in vitro efficacy and toxicity was tested on HIV-infected and uninfected cell cultures. One directlHIV-specific (p24 antigen ELISA assay) and one indirect (Luciferase) assays were used to asses the inhibition of HIV replication caused by ABC. The p24 antigen ELISA (Enzyme-Linked ImmunoSorbent Assay) assay required a lot of washing steps and were rather expensive to use. The Luciferase assay was only used on the M7-Luc cells; this assay was sensitive, inexpensive and easy to use. The MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) viability assay was used to measure the toxicity caused by the Pheroid ™ and/or ABC on the cells. MTT is a widely used quantitative colorimetric assay to measure the viability of cells. The vitamin E and antioxidants contained in the Pheroid ™ reduced the MTT and produced results that were misinterpreted as enhanced viability when the Pheroid™ was present during MTT analysis. To prevent this problem an additional washing step should be introduced prior to analysis to reduce the interference of the Pheroid ™ with analytical methods. In conclusion, the efficacy of ABC entrapped within the Pheroid™ is still inconclusive and further studies will have to be done. MTT should be used with care for viability analysis of cells incubated in the presence of Pheroid TM. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.
3

The viability of an Interactive Geographic Information System Tutor (I-GIS-T) application within the FET phase / Elfrieda Marie-Louise Fleischmann

Fleischmann, Elfrieda Marie-Louise January 2012 (has links)
When comparing numerous educational advantages of Geographic Information Systems (GIS) with the slow integration of GIS practice within education globally, results are confounding. This paradoxical development is also found within South Africa. In fact, GIS has been included in the Further Education and Training (FET) phase by the Department of Basic Education (DoBE) since 2006. However, following the same global trend, curriculum development in South Africa has outpaced educational GIS software research. In addition, the e-learning White paper of SA also urges software development. Barriers hindering GIS practice include the lack of suitable curriculum-aligned GIS software within the South African digital divide context. A need therefore exists for further research regarding educational GIS practice applications within South Africa. Bearing this in mind, a case study was done investigating the viability of an educationally orientated Interactive-GIS-Tutor (I-GIS-T) application within FET phase in Geography. The study was conducted with the grade 11 Geography learners of a secondary school in a rural area of KwaZulu-Natal, as well as with their Geography teacher and two other Geography teachers of the same school. These three teachers have different ICT/GIS abilities and years of teaching experience. Furthermore, the study aimed to identify the main GIS educational barriers, globally and locally, as well as to investigate the viability of the I-GIS-T in relation to these identified barriers. The strategy followed was a case study evaluation, with a qualitative approach to data collection and analysis, supported by quantitative data, since this was most suited to the research questions and context. Pragmatism was therefore the underpinning philosophy within this case study. One-on-one semi-structured teacher interviews were conducted to identify the main barriers of GIS education within the FET phases. Data collection by means of questionnaires, individual interviews, focus group interviews, video recordings and field notes provided a thick description regarding the viability of the I-GIS-T within the natural class setting. ATLAS.tiTM and SPSS software were utilised with analysis of qualitative and supportive quantitative data. Attitudinal tests provided supportive quantitative data. Findings indicated that main GIS practice barriers, globally as well as in the school of study, were the lack of preparation time, a full curriculum, lack of GIS support, complex educational GIS software and the teacher‟s lack of ICT skills. The grade 11 Geography teacher and most of the learners evaluated the I-GIS-T as workable. The I-GIS-T also surmounted the main GIS practice barriers. Furthermore, GIS attitudinal tests revealed an overall positive shift on all the attitudinal questions. The combination of lack of basic computer skills and language (where English is not the mother tongue) were the main reasons why some learners suggested that they struggled with the software. Future I-GIS-T development recommended incorporation of a multi-language choice component, as well as exploratory activities. Within this case study, learners who have mastered basic computer skills found the I-GIS-T effective and workable and therefore a viable GIS software application option within the FET phase Geography. In order to be able to generalise statistically, further quantitative research is suggested. In fact, future quantitative research, employing SEM (Structural Equation Modeling) within the Technology Acceptance Model (TAM) might prove the I-GIS-T to be a viable option within FET schools throughout SA, as well as in other developing countries. / Thesis (MEd (Curriculum Development))--North-West University, Potchefstroom Campus, 2013
4

The viability of an Interactive Geographic Information System Tutor (I-GIS-T) application within the FET phase / Elfrieda Marie-Louise Fleischmann

Fleischmann, Elfrieda Marie-Louise January 2012 (has links)
When comparing numerous educational advantages of Geographic Information Systems (GIS) with the slow integration of GIS practice within education globally, results are confounding. This paradoxical development is also found within South Africa. In fact, GIS has been included in the Further Education and Training (FET) phase by the Department of Basic Education (DoBE) since 2006. However, following the same global trend, curriculum development in South Africa has outpaced educational GIS software research. In addition, the e-learning White paper of SA also urges software development. Barriers hindering GIS practice include the lack of suitable curriculum-aligned GIS software within the South African digital divide context. A need therefore exists for further research regarding educational GIS practice applications within South Africa. Bearing this in mind, a case study was done investigating the viability of an educationally orientated Interactive-GIS-Tutor (I-GIS-T) application within FET phase in Geography. The study was conducted with the grade 11 Geography learners of a secondary school in a rural area of KwaZulu-Natal, as well as with their Geography teacher and two other Geography teachers of the same school. These three teachers have different ICT/GIS abilities and years of teaching experience. Furthermore, the study aimed to identify the main GIS educational barriers, globally and locally, as well as to investigate the viability of the I-GIS-T in relation to these identified barriers. The strategy followed was a case study evaluation, with a qualitative approach to data collection and analysis, supported by quantitative data, since this was most suited to the research questions and context. Pragmatism was therefore the underpinning philosophy within this case study. One-on-one semi-structured teacher interviews were conducted to identify the main barriers of GIS education within the FET phases. Data collection by means of questionnaires, individual interviews, focus group interviews, video recordings and field notes provided a thick description regarding the viability of the I-GIS-T within the natural class setting. ATLAS.tiTM and SPSS software were utilised with analysis of qualitative and supportive quantitative data. Attitudinal tests provided supportive quantitative data. Findings indicated that main GIS practice barriers, globally as well as in the school of study, were the lack of preparation time, a full curriculum, lack of GIS support, complex educational GIS software and the teacher‟s lack of ICT skills. The grade 11 Geography teacher and most of the learners evaluated the I-GIS-T as workable. The I-GIS-T also surmounted the main GIS practice barriers. Furthermore, GIS attitudinal tests revealed an overall positive shift on all the attitudinal questions. The combination of lack of basic computer skills and language (where English is not the mother tongue) were the main reasons why some learners suggested that they struggled with the software. Future I-GIS-T development recommended incorporation of a multi-language choice component, as well as exploratory activities. Within this case study, learners who have mastered basic computer skills found the I-GIS-T effective and workable and therefore a viable GIS software application option within the FET phase Geography. In order to be able to generalise statistically, further quantitative research is suggested. In fact, future quantitative research, employing SEM (Structural Equation Modeling) within the Technology Acceptance Model (TAM) might prove the I-GIS-T to be a viable option within FET schools throughout SA, as well as in other developing countries. / Thesis (MEd (Curriculum Development))--North-West University, Potchefstroom Campus, 2013

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