Determinants of type 2 Diabetes mellitus among HIV/AIDS patients on antiretroviral drugs in the OR Tambo District, SA
- Authors: Nokwanda Edith Bam
- Date: 2018
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2073 , vital:40815
- Description: Background: Type 2 Diabetes mellitus (DM) is increasing in the context of HIV/AIDS as a result of the long-term effects of ARVS. Little is documented in South Africa on the determinants of type 2 DM in HIV/AIDS population although the prevalence is high (Moyo, et al., 2014). The purpose of this study was to describe the determinants of type 2 diabetes mellitus among HIV/AIDS patients on ARVS in the OR Tambo District. Methods: A quantitative research methodology using a case control retrospective study was used to describe the determinants of type 2 DM among HIV/AIDS patients in OR Tambo District. A sample of 177 (33%) cases with HIV/AIDS and type 2 DM was selected using a one stage stratified sampling with allocation proportion to size of each stratum of the four sub-districts of OR Tambo District. For example KSD 80 cases, Nyandeni 43; Qaukeni 36 and Mhlontlo 18. Two non-diabetic patients with HIV/AIDS were selected as controls per case unpaired and totalled up to 354 (67%) controls. A self - administration questionnaire adopted from WHO stepwise surveillance tool was used for data collection. Results: Findings of the study revealed five determinants of type 2 diabetes mellitus grouped as the socio-demographic determinants, levels of physical activities, types of diets, arterial blood pressure and body weight and types of combination antiretroviral therapies used in HIV/AIDS therapy. In addition the association of type 2 DM with HIV was shown to include ARV complications, number of years on ARVS and the tri-therapy versus fixed dose combination. Conclusion: Type 2 DM is a major complication of ARVS experienced by the cases at n=108 (61%) compared to others such as lipodystrophy n=10 (5.6%), skin disorders n=7 (3.9%) and bad dreams n=2 (1%). Consequently a multi-morbidity situation co-exists among the cases creating as shift from as single disease to a multiple-disease focus namely ARVS, anti-DM, anti-HPT etc. Recommendations on the HIV/AIDS and type 2 DM awareness and care intervention strategy were made to improve the health outcomes of type 2 DM patients in HIV/AIDS context in OR Tambo District.
- Full Text:
- Authors: Nokwanda Edith Bam
- Date: 2018
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2073 , vital:40815
- Description: Background: Type 2 Diabetes mellitus (DM) is increasing in the context of HIV/AIDS as a result of the long-term effects of ARVS. Little is documented in South Africa on the determinants of type 2 DM in HIV/AIDS population although the prevalence is high (Moyo, et al., 2014). The purpose of this study was to describe the determinants of type 2 diabetes mellitus among HIV/AIDS patients on ARVS in the OR Tambo District. Methods: A quantitative research methodology using a case control retrospective study was used to describe the determinants of type 2 DM among HIV/AIDS patients in OR Tambo District. A sample of 177 (33%) cases with HIV/AIDS and type 2 DM was selected using a one stage stratified sampling with allocation proportion to size of each stratum of the four sub-districts of OR Tambo District. For example KSD 80 cases, Nyandeni 43; Qaukeni 36 and Mhlontlo 18. Two non-diabetic patients with HIV/AIDS were selected as controls per case unpaired and totalled up to 354 (67%) controls. A self - administration questionnaire adopted from WHO stepwise surveillance tool was used for data collection. Results: Findings of the study revealed five determinants of type 2 diabetes mellitus grouped as the socio-demographic determinants, levels of physical activities, types of diets, arterial blood pressure and body weight and types of combination antiretroviral therapies used in HIV/AIDS therapy. In addition the association of type 2 DM with HIV was shown to include ARV complications, number of years on ARVS and the tri-therapy versus fixed dose combination. Conclusion: Type 2 DM is a major complication of ARVS experienced by the cases at n=108 (61%) compared to others such as lipodystrophy n=10 (5.6%), skin disorders n=7 (3.9%) and bad dreams n=2 (1%). Consequently a multi-morbidity situation co-exists among the cases creating as shift from as single disease to a multiple-disease focus namely ARVS, anti-DM, anti-HPT etc. Recommendations on the HIV/AIDS and type 2 DM awareness and care intervention strategy were made to improve the health outcomes of type 2 DM patients in HIV/AIDS context in OR Tambo District.
- Full Text:
Phenotypic and molecular characterization of clinical isolates of s. Aureus and s. Epidermidis in the Eastern Cape province, South Africa : evaluation of plant-derived compounds
- Mthethwa, Ntombeziningi Shirley
- Authors: Mthethwa, Ntombeziningi Shirley
- Date: 2015
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2030 , vital:40805 , Doctor Of Philosophy (Health Sciences) Medical Microbiology
- Description: Staphylococcal species are known pathogens that are responsible for an extensive array of clinical manifestations in humans of diverse age groups in different settings and countries. They are responsible for cases of food poisoning, toxic shock syndrome, staphylococcal scalded skin syndrome, carbuncles, meningitis, among others. High level of antibiotic resistance patterns are common among isolates from different sources. The quest to discover alternative therapeutic regimes by use of medicinal plants are now topical and the subject of research activities. The aim of this study was to determine the prevalence and antibiotic resistant patterns of Staphylococcus aureus and Staphylococcus epidermidis isolated from patients attending different hospitals and clinics in rural communities around Mthatha; determine the activity of medicinal plants against S. aureus and S. epidermidis, including the characterisation of active compounds; ascertain phylogenetic relatedness of isolates; determine the genes coding for resistance in both pathogens and assess the role of human sera samples from different blood groups against S. aureus and S. epidermidis . In order to achieve these goals, the following aspects were explored and are hereby presented in chapters. Chapter one focused on the general introduction and literature review. The morphology, cultural characteristics, laboratory diagnosis, pathogenesis, antibiograms and clinical manifestations of Staphylococcus epidermidis and Staphylococcus aureus were reviewed. Furthermore the activities of medicinal plants and their various applications in the management of infections in different countries, including their possible active compounds and toxicity levels were also explored in an endeavour to provide suitable background for the study. iii The activity of human serum samples from different blood groups and their kinetics were also foregrounded. In Chapter 2, the antimicrobial susceptibility, genes coding for resistance and pathogenesis, and phylogenetic relatedness in S. aureus and S. epidermidis were investigated. Samples were collected from the Nelson Mandela Academic Hospital, Mthatha General Hospital and other samples were received from surrounding satellite hospitals. Samples were analysed using Kirby Bauer disk diffusion (antibiotic susceptibility testing), micro-broth dilution (MIC) and conventional PCR for the investigation of the genes (mecA, luks-lukf, msrA, ermA, ermC and icaA) responsible for resistance, virulence and pathogenesis of isolates. RAPD-PCR (Random Amplified Polymorphic DNA – Polymerase Chain Reaction) was used to determine phylogenetic relatedness amongst the S. aureus and S. epidermidis isolates. Results indicated that wound swabs and blood cultures were identified as the main sources of S. aureus and S. epidermidis and prevalence rates in children less than eleven years (25.7%) (S. aureus) and (7%) (S. epidermidis) were recorded. Vancomycin had the highest activity against both S. aureus and S. epidermidis, penicillin had the lowest activity.There were no significant differences in resistance patterns among different age groups and gender (p>0.01). Ninety three percent of S. aureus that were confirmed as MRSA with PCR method possessed mecA gene, whilst 16% of S. epidermidis had mecA and 33% possessed icaA gene. Fifty eight percent (58%) of S. aureus possessed luks-lukf PVL gene suggesting that it may have been acquired from the community. Forty two percent 42% of msrA was detected in S. epidermidis, 43% ermC and 34% ermA were detected in S. aureus isolates. Eleven percent 11% of S. aureus isolates were found to carry both ermA and ermC genes. mecA and luks-lufPV genes are implicated in iv methicillin resistant S. aureus that causes necrotizing pnemoniae and icaA is implicated in the formation of biofilm, another mechanism of resistance in S. epidermidis. RAPD profile resulting in DNA amplification fragments ranged in size from 300 to 1500 bp. The RAPD patterns obtained showed various trends among isolates meaning that S. aureus and S. epidermidis isolates investigated had high diversity among them. Dendograms constructed with each oligonucleotide showed that PCR patterns obtained with primer OPL11 (S. aureus) and ERIC1 (S. epidermidis) strains had genetic similarity indices ranging from 0.009 to 0.329. This wide range of similarity indices indicated a high level of DNA polymorphism among S. aureus and S. epidermidis isolates. Knowledge of the genes coding for resistance in this study will address the gaps in the mechanisms of resistance for effective intervention strategies. The infections caused by multi-resistant strains of Staphylococcal species represent an important problem that affects many health institutions. Due to the large number of patients infected with S. aureus and S. epidermidis and the diverse possibilities of contamination, it is always necessary to review the evolution of antimicrobial resistance and the therapeutic responses of the bacterial strains. This aspect of the study provides updated data on susceptibility patterns of local isolates of S. aureus and S. epidermidis for use in empiric management of patients including the various genes coding for resistance in the designated pathogens and their phylogenetic relatedness. Chapter 3 presents the antimicrobial and anti-HIV1 activities of selected medicinal plants from the Eastern Cape Province used for treating skin and respiratory tract infections. Anti-HIV activities were investigated because of the role of staphylococcal v species as opportunistic pathogens in HIV infections. Four medicinal plants were evaluated for antimicrobial activities and cytotoxicity on clinical isolates of S. aureus and S. epidermidis. Medicinal plants used in this study were Cassine transvaalensis, Croton gratissimus, Vangueria infausta and Vitex ferruginea. The Kirby-Bauer disk diffusion and 96 well microtiter plate methods were used in the antimicrobial activity studies but for the anti-HIV1 activity, MAGI assay was used. Microtetrazolium assay (MTT) was used for the evaluation of cytotoxicity of plants. Bio-autographic assay was used to locate the position of the active compound using Rf value; thin layer chromatography and column chromatography were used in the isolation of active compounds and NMR was used in the identification and structural elucidation of the active compounds. C. transvaalensis and V. infausta were found to possess high activity against S. aureus and S. epidermidis with the lowest MIC of 0.02. In the anti HIV1 MAGI assay, C. transvaalensis and C. gratissimus showed activity against HIV1. C. transvaalensis and C. grattisimus possessed high level of toxicity with CC50 reading of 0.2 while V. infausta and V. ferruginea had reading of 0.1. Two triterpenoids were successfully isolated in C. transvaalensis. Elucidation of the structure of active compounds of plant extracts of medicinal plants provides suitable templates for candidate drug designs and drug discovery. Such potential application will be contingent on the results of cytotoxicity testing and this underlines the significance of the test. Human serum is an important host defence mechanism against disease causing agents. Chapter four evaluates the bactericidal activity of different blood groups. Blood samples of different blood groups were screened for the presence of antibodies against S. aureus and S. epidermidis using agglutination test. Serum sensitivity assay vi was employed for susceptibility testing of S. aureus and S. epidermidis to blood samples. The Gunea-pig serum was used to determine the role of complement in serum bactericidal activity. The results showed that S. aureus and S. epidermidis were highly sensitive to normal human sera from blood group B with a percentage of 61% (S. aureus) and 83.3% (S. epidermidis). When the role of complement in bactericidal activity of the serum to staphylococci species was assessed it was shown that when both S. aureus and S. epidermidis were incubated with individual sera of blood groups and pooled serum of the same blood groups, the organisms were serum sensitive. The findings showed that different individual and pooled serum samples had a role to play in the defence mechanisms of individuals against S. aureus and S. epidermidis. In general the study provides a reference document on S. aureus and S. epidermidis in terms of their antibiograms, molecular characterization, sensitivity to human sera and susceptibility to medicinal plant extracts. Cytotoxicity profiles of the medicinal plants are also reported. Due to the on-going need to expand on the frontiers of knowledge, it is therefore recommended, as a way of building on this study, extensive investigations on the epidemiology of S. epidermidis, S. aureus and related pathogens to be conducted because studies of this nature have been limited by the fact that S. epidermidis strains are often considered to be contaminants. High-level surveillance of clinical samples of MRSA to define the instance and spread of CA-MRSA and HA-MRSA in hospital settings including health care workers and patients are also warranted in addition to further anti -cancer activities and cytotoxicity tests.
- Full Text:
- Authors: Mthethwa, Ntombeziningi Shirley
- Date: 2015
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2030 , vital:40805 , Doctor Of Philosophy (Health Sciences) Medical Microbiology
- Description: Staphylococcal species are known pathogens that are responsible for an extensive array of clinical manifestations in humans of diverse age groups in different settings and countries. They are responsible for cases of food poisoning, toxic shock syndrome, staphylococcal scalded skin syndrome, carbuncles, meningitis, among others. High level of antibiotic resistance patterns are common among isolates from different sources. The quest to discover alternative therapeutic regimes by use of medicinal plants are now topical and the subject of research activities. The aim of this study was to determine the prevalence and antibiotic resistant patterns of Staphylococcus aureus and Staphylococcus epidermidis isolated from patients attending different hospitals and clinics in rural communities around Mthatha; determine the activity of medicinal plants against S. aureus and S. epidermidis, including the characterisation of active compounds; ascertain phylogenetic relatedness of isolates; determine the genes coding for resistance in both pathogens and assess the role of human sera samples from different blood groups against S. aureus and S. epidermidis . In order to achieve these goals, the following aspects were explored and are hereby presented in chapters. Chapter one focused on the general introduction and literature review. The morphology, cultural characteristics, laboratory diagnosis, pathogenesis, antibiograms and clinical manifestations of Staphylococcus epidermidis and Staphylococcus aureus were reviewed. Furthermore the activities of medicinal plants and their various applications in the management of infections in different countries, including their possible active compounds and toxicity levels were also explored in an endeavour to provide suitable background for the study. iii The activity of human serum samples from different blood groups and their kinetics were also foregrounded. In Chapter 2, the antimicrobial susceptibility, genes coding for resistance and pathogenesis, and phylogenetic relatedness in S. aureus and S. epidermidis were investigated. Samples were collected from the Nelson Mandela Academic Hospital, Mthatha General Hospital and other samples were received from surrounding satellite hospitals. Samples were analysed using Kirby Bauer disk diffusion (antibiotic susceptibility testing), micro-broth dilution (MIC) and conventional PCR for the investigation of the genes (mecA, luks-lukf, msrA, ermA, ermC and icaA) responsible for resistance, virulence and pathogenesis of isolates. RAPD-PCR (Random Amplified Polymorphic DNA – Polymerase Chain Reaction) was used to determine phylogenetic relatedness amongst the S. aureus and S. epidermidis isolates. Results indicated that wound swabs and blood cultures were identified as the main sources of S. aureus and S. epidermidis and prevalence rates in children less than eleven years (25.7%) (S. aureus) and (7%) (S. epidermidis) were recorded. Vancomycin had the highest activity against both S. aureus and S. epidermidis, penicillin had the lowest activity.There were no significant differences in resistance patterns among different age groups and gender (p>0.01). Ninety three percent of S. aureus that were confirmed as MRSA with PCR method possessed mecA gene, whilst 16% of S. epidermidis had mecA and 33% possessed icaA gene. Fifty eight percent (58%) of S. aureus possessed luks-lukf PVL gene suggesting that it may have been acquired from the community. Forty two percent 42% of msrA was detected in S. epidermidis, 43% ermC and 34% ermA were detected in S. aureus isolates. Eleven percent 11% of S. aureus isolates were found to carry both ermA and ermC genes. mecA and luks-lufPV genes are implicated in iv methicillin resistant S. aureus that causes necrotizing pnemoniae and icaA is implicated in the formation of biofilm, another mechanism of resistance in S. epidermidis. RAPD profile resulting in DNA amplification fragments ranged in size from 300 to 1500 bp. The RAPD patterns obtained showed various trends among isolates meaning that S. aureus and S. epidermidis isolates investigated had high diversity among them. Dendograms constructed with each oligonucleotide showed that PCR patterns obtained with primer OPL11 (S. aureus) and ERIC1 (S. epidermidis) strains had genetic similarity indices ranging from 0.009 to 0.329. This wide range of similarity indices indicated a high level of DNA polymorphism among S. aureus and S. epidermidis isolates. Knowledge of the genes coding for resistance in this study will address the gaps in the mechanisms of resistance for effective intervention strategies. The infections caused by multi-resistant strains of Staphylococcal species represent an important problem that affects many health institutions. Due to the large number of patients infected with S. aureus and S. epidermidis and the diverse possibilities of contamination, it is always necessary to review the evolution of antimicrobial resistance and the therapeutic responses of the bacterial strains. This aspect of the study provides updated data on susceptibility patterns of local isolates of S. aureus and S. epidermidis for use in empiric management of patients including the various genes coding for resistance in the designated pathogens and their phylogenetic relatedness. Chapter 3 presents the antimicrobial and anti-HIV1 activities of selected medicinal plants from the Eastern Cape Province used for treating skin and respiratory tract infections. Anti-HIV activities were investigated because of the role of staphylococcal v species as opportunistic pathogens in HIV infections. Four medicinal plants were evaluated for antimicrobial activities and cytotoxicity on clinical isolates of S. aureus and S. epidermidis. Medicinal plants used in this study were Cassine transvaalensis, Croton gratissimus, Vangueria infausta and Vitex ferruginea. The Kirby-Bauer disk diffusion and 96 well microtiter plate methods were used in the antimicrobial activity studies but for the anti-HIV1 activity, MAGI assay was used. Microtetrazolium assay (MTT) was used for the evaluation of cytotoxicity of plants. Bio-autographic assay was used to locate the position of the active compound using Rf value; thin layer chromatography and column chromatography were used in the isolation of active compounds and NMR was used in the identification and structural elucidation of the active compounds. C. transvaalensis and V. infausta were found to possess high activity against S. aureus and S. epidermidis with the lowest MIC of 0.02. In the anti HIV1 MAGI assay, C. transvaalensis and C. gratissimus showed activity against HIV1. C. transvaalensis and C. grattisimus possessed high level of toxicity with CC50 reading of 0.2 while V. infausta and V. ferruginea had reading of 0.1. Two triterpenoids were successfully isolated in C. transvaalensis. Elucidation of the structure of active compounds of plant extracts of medicinal plants provides suitable templates for candidate drug designs and drug discovery. Such potential application will be contingent on the results of cytotoxicity testing and this underlines the significance of the test. Human serum is an important host defence mechanism against disease causing agents. Chapter four evaluates the bactericidal activity of different blood groups. Blood samples of different blood groups were screened for the presence of antibodies against S. aureus and S. epidermidis using agglutination test. Serum sensitivity assay vi was employed for susceptibility testing of S. aureus and S. epidermidis to blood samples. The Gunea-pig serum was used to determine the role of complement in serum bactericidal activity. The results showed that S. aureus and S. epidermidis were highly sensitive to normal human sera from blood group B with a percentage of 61% (S. aureus) and 83.3% (S. epidermidis). When the role of complement in bactericidal activity of the serum to staphylococci species was assessed it was shown that when both S. aureus and S. epidermidis were incubated with individual sera of blood groups and pooled serum of the same blood groups, the organisms were serum sensitive. The findings showed that different individual and pooled serum samples had a role to play in the defence mechanisms of individuals against S. aureus and S. epidermidis. In general the study provides a reference document on S. aureus and S. epidermidis in terms of their antibiograms, molecular characterization, sensitivity to human sera and susceptibility to medicinal plant extracts. Cytotoxicity profiles of the medicinal plants are also reported. Due to the on-going need to expand on the frontiers of knowledge, it is therefore recommended, as a way of building on this study, extensive investigations on the epidemiology of S. epidermidis, S. aureus and related pathogens to be conducted because studies of this nature have been limited by the fact that S. epidermidis strains are often considered to be contaminants. High-level surveillance of clinical samples of MRSA to define the instance and spread of CA-MRSA and HA-MRSA in hospital settings including health care workers and patients are also warranted in addition to further anti -cancer activities and cytotoxicity tests.
- Full Text:
THE EFFECT OF DIET ON THE PATTERN OF GASTROOESOPHAGEAL REFLUX IN THE RURAL SETTING OF THE EASTERN CAPE
- Authors: NDEBIA EUGENE JAMOT
- Date: 2015
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2051 , vital:40807
- Description: Gastro-oesophageal reflux is the return of stomach contents back up into the oesophagus. Excessive reflux of acid content into the oesophagus can cause oesophageal disorders such as heartburn, gastro-oesophageal reflux disease and oesophagitis. The prevalence of oesophageal disorders appears to be high in North America, Europe, japan and China while epidemiology data from Africa, South America and Middle East are unknown. More data is required in Africa because population diversity in reflux symptoms may exist and it is important that standard reference ranges of reflux profiles are established for African countries. The aims of this study was to establish a data base of gastro-oesophageal reflux pattern in the Eastern Cape rural area, to compare our findings with similar western studies and to establish the effect diet, H. pylori infection, gender, weight and age on the observed reflux pattern. The reflux pattern was evaluated in healthy subjects for 24h using the newer technique involving the recording of eosophageal intraluminal impedance and pH simultaneously. The technique gives quantitative data on the frequency, nature, type, and duration, and correlates them to the pH of the reflux. The diet survey was done using the usual pattern diet questionnaire, the body mass index (BMI) was calculated and the quantification of H. pylori antibodies IgG was determined in the serum of each participant using an ELISA kit. In total, 77 participants including 48 females and 29 males were included in the study. The mean age was 35 (range 18 - 60) years for females and 37 (range 18 - 54) for males. The mean BMI was 29 (range 19 - 42) for females and 23 (range 18- ii 30) for males. The total number of refluxes recorded in 24h in this population was presented as median, 25th, 75th and 95th percentile corresponding to 49, 29, 65 and 97, respectively. Of these, 37 % were acidic, 43 % were weakly acidic and 20 % were non-acidic. In term of reflux composition 12 % were liquid, 24 % were gas (belches) and 64 % were mixed (gas and liquid). The oesophageal bolus clearance time was 18 s while the acidity of the reflux was completely neutralised 30 s after a reflux. The oesophageal bolus exposure time was 14 min/day and while acid exposure time was 15 min/day. More refluxes were found in upright position compared to supine position. They were a higher number of refluxes and a predominance of non-acid reflux in the present study compared to western countries. We found that most refluxes were postprandial and some parameters of the pattern of gastro-oesophageal reflux were significantly influenced by the traditional diet. Higher carbohydrate, protein and fat in the meal were associated with a high frequency of refluxes most of which were acidic and weakly acidic while higher fruit and vegetable consumption was associated with fewer refluxes. An increased number of non-acid refluxes were observed in high carbohydrate maize based diet. Nearly all participants of the present study were positive for H. pylori and those with a higher concentration of H. pylori IgG in the serum had less oesophageal acid exposure. Females, older and overweight participants presented with an increased frequency of reflux. This study provides normal references values for the pattern of Gastrooesophageal reflux in the rural population of South Africa. The observed pattern of reflux is positively influenced by the traditional diet which is mainly carbohydrate maize based and also by BMI, weight and gender
- Full Text:
- Authors: NDEBIA EUGENE JAMOT
- Date: 2015
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2051 , vital:40807
- Description: Gastro-oesophageal reflux is the return of stomach contents back up into the oesophagus. Excessive reflux of acid content into the oesophagus can cause oesophageal disorders such as heartburn, gastro-oesophageal reflux disease and oesophagitis. The prevalence of oesophageal disorders appears to be high in North America, Europe, japan and China while epidemiology data from Africa, South America and Middle East are unknown. More data is required in Africa because population diversity in reflux symptoms may exist and it is important that standard reference ranges of reflux profiles are established for African countries. The aims of this study was to establish a data base of gastro-oesophageal reflux pattern in the Eastern Cape rural area, to compare our findings with similar western studies and to establish the effect diet, H. pylori infection, gender, weight and age on the observed reflux pattern. The reflux pattern was evaluated in healthy subjects for 24h using the newer technique involving the recording of eosophageal intraluminal impedance and pH simultaneously. The technique gives quantitative data on the frequency, nature, type, and duration, and correlates them to the pH of the reflux. The diet survey was done using the usual pattern diet questionnaire, the body mass index (BMI) was calculated and the quantification of H. pylori antibodies IgG was determined in the serum of each participant using an ELISA kit. In total, 77 participants including 48 females and 29 males were included in the study. The mean age was 35 (range 18 - 60) years for females and 37 (range 18 - 54) for males. The mean BMI was 29 (range 19 - 42) for females and 23 (range 18- ii 30) for males. The total number of refluxes recorded in 24h in this population was presented as median, 25th, 75th and 95th percentile corresponding to 49, 29, 65 and 97, respectively. Of these, 37 % were acidic, 43 % were weakly acidic and 20 % were non-acidic. In term of reflux composition 12 % were liquid, 24 % were gas (belches) and 64 % were mixed (gas and liquid). The oesophageal bolus clearance time was 18 s while the acidity of the reflux was completely neutralised 30 s after a reflux. The oesophageal bolus exposure time was 14 min/day and while acid exposure time was 15 min/day. More refluxes were found in upright position compared to supine position. They were a higher number of refluxes and a predominance of non-acid reflux in the present study compared to western countries. We found that most refluxes were postprandial and some parameters of the pattern of gastro-oesophageal reflux were significantly influenced by the traditional diet. Higher carbohydrate, protein and fat in the meal were associated with a high frequency of refluxes most of which were acidic and weakly acidic while higher fruit and vegetable consumption was associated with fewer refluxes. An increased number of non-acid refluxes were observed in high carbohydrate maize based diet. Nearly all participants of the present study were positive for H. pylori and those with a higher concentration of H. pylori IgG in the serum had less oesophageal acid exposure. Females, older and overweight participants presented with an increased frequency of reflux. This study provides normal references values for the pattern of Gastrooesophageal reflux in the rural population of South Africa. The observed pattern of reflux is positively influenced by the traditional diet which is mainly carbohydrate maize based and also by BMI, weight and gender
- Full Text:
ARTERIAL TONE IN BLACK WOMEN WITH PREECLAMPSIA FROM TRANSKEI REGION OF SOUTH AFRICA
- Authors: AMBROSE VINCENT NAMUGOWA
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2016 , vital:40802 , DOCTOR OF PHILOSOPHY (Ph.D) (In Health Sciences, Physiology)
- Description: Women with pre-eclampsia have an increased risk of cardiovascular disease later in life. The mechanisms which mediate this heightened risk are poorly understood; it was long believed that pre-eclampsia was cured by delivery of the foetus. But it is now apparent that the risks of complications persist for some time after delivery. The aim of the study was to establish the presence and pattern of endothelial dysfunction during gestation and postpartum among women who develop preeclampsia in the Transkei region of South Africa. This was a two parts study: part one was a cross-sectional experimental study, which involved 85 women with established pre-eclampsia (PE) and 112 pregnant controls (PC); part two was a prospective longitudinal study which involved 36 previously pre-eclamptic women and 86 non-pregnant controls (NPC). Maternal wave reflection (augmentation index) and carotid-femoral pulse wave velocity were assessed noninvasively, using applanation tonometry with the SphygmoCor device. Endothelial function was assessed by EndoPAT 2000 device; pneumatic probes were fitted to the index fingers; induced flow-mediated reactive hyperaemia; the ratio of the readings before and after occlusion was then used to calculate the score, the reactive hyperaemia index (RHI) as a measure of endothelial function. In part one, the measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the pregnant control group.PE group compared with pregnant controls, PE had higher median pulse wave velocity [1.2 inter-quartile range (IQR) 1.08-1.35 MoM vs. 0.97, IQR 8.6-1.09 MoM; p=0.0000].In contrast, there were no ii significant differences between the two groups median of central augmentation index (1.0, IQR -0.4 -1.7 MoM vs. 0.9, IQR 0.69-1.36 MoM; p=0.765). RHI was higher in PE than controls (1.16, IQR 1-1.33 MoM vs. 1, IQR 0.9- 1.18 MoM; p=0.0000). Early-onset pre-eclampsia had higher median brachial blood pressure (87.5, IQR 79-101 vs. 82, IQR 65-88 mmHg; p=0.02), higher mean arterial pressure (110, IQR97-120 vs.101 IQR 88-110 mmHg; p=0.04) and higher central diastolic blood pressure (90, IQR 80-103 vs.84, IQR 67-90 mmHg; p=0.017) than the lateonset pre-eclampsia. Pulse wave velocity (carotid-femoral) was increased in pregnant women with preeclampsia during the third trimester. Reactive hyperaemia index, a measure of endothelial function, was higher in pregnant women with pre-eclampsia than pregnant controls. This suggests that regional (aortic) arterial stiffness is increased, but endothelial function, as assessed by ENDOPAT 2000 device, was not compromised in rural African women with pre-eclampsia. Pulse wave reflection, as assessed by augmentation index adjusted to heart rate of 75 beats/min, was increased in women who had early-onset pre-eclampsia more than those with late-onset pre-eclampsia. Brachial diastolic blood pressure was higher in early-onset pre-eclampsia which resulted in lower brachial pulse pressure than in the late-onset pre-eclampsia. Furthermore, the mean arterial pressure was higher in early-onset than late onset pre-eclampsia. This suggests that early onset pre-eclampsia is more severe condition than the late-onset pre-eclampsia. In part two, pulse wave velocity remained significantly higher in previously preeclamptic women than non-pregnant controls up to three months after delivery iii (p<0.05).Then it reduced to non significant values. Regional (aortic) arterial stiffness, though it persists for some time after delivery, it is transitory in previously pre-eclamptic women from the rural Africa setting. All blood pressure indices (central and brachial pressures), were increased in women who previously had pre-eclampsia as compared to non pregnant controls up to one year postpartum. Although pulse wave velocity and augmentation decrease to low values with time after delivery increased blood pressure is an indication of compromised arterial compliance in women with previously pre-eclampsia.
- Full Text:
- Authors: AMBROSE VINCENT NAMUGOWA
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2016 , vital:40802 , DOCTOR OF PHILOSOPHY (Ph.D) (In Health Sciences, Physiology)
- Description: Women with pre-eclampsia have an increased risk of cardiovascular disease later in life. The mechanisms which mediate this heightened risk are poorly understood; it was long believed that pre-eclampsia was cured by delivery of the foetus. But it is now apparent that the risks of complications persist for some time after delivery. The aim of the study was to establish the presence and pattern of endothelial dysfunction during gestation and postpartum among women who develop preeclampsia in the Transkei region of South Africa. This was a two parts study: part one was a cross-sectional experimental study, which involved 85 women with established pre-eclampsia (PE) and 112 pregnant controls (PC); part two was a prospective longitudinal study which involved 36 previously pre-eclamptic women and 86 non-pregnant controls (NPC). Maternal wave reflection (augmentation index) and carotid-femoral pulse wave velocity were assessed noninvasively, using applanation tonometry with the SphygmoCor device. Endothelial function was assessed by EndoPAT 2000 device; pneumatic probes were fitted to the index fingers; induced flow-mediated reactive hyperaemia; the ratio of the readings before and after occlusion was then used to calculate the score, the reactive hyperaemia index (RHI) as a measure of endothelial function. In part one, the measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the pregnant control group.PE group compared with pregnant controls, PE had higher median pulse wave velocity [1.2 inter-quartile range (IQR) 1.08-1.35 MoM vs. 0.97, IQR 8.6-1.09 MoM; p=0.0000].In contrast, there were no ii significant differences between the two groups median of central augmentation index (1.0, IQR -0.4 -1.7 MoM vs. 0.9, IQR 0.69-1.36 MoM; p=0.765). RHI was higher in PE than controls (1.16, IQR 1-1.33 MoM vs. 1, IQR 0.9- 1.18 MoM; p=0.0000). Early-onset pre-eclampsia had higher median brachial blood pressure (87.5, IQR 79-101 vs. 82, IQR 65-88 mmHg; p=0.02), higher mean arterial pressure (110, IQR97-120 vs.101 IQR 88-110 mmHg; p=0.04) and higher central diastolic blood pressure (90, IQR 80-103 vs.84, IQR 67-90 mmHg; p=0.017) than the lateonset pre-eclampsia. Pulse wave velocity (carotid-femoral) was increased in pregnant women with preeclampsia during the third trimester. Reactive hyperaemia index, a measure of endothelial function, was higher in pregnant women with pre-eclampsia than pregnant controls. This suggests that regional (aortic) arterial stiffness is increased, but endothelial function, as assessed by ENDOPAT 2000 device, was not compromised in rural African women with pre-eclampsia. Pulse wave reflection, as assessed by augmentation index adjusted to heart rate of 75 beats/min, was increased in women who had early-onset pre-eclampsia more than those with late-onset pre-eclampsia. Brachial diastolic blood pressure was higher in early-onset pre-eclampsia which resulted in lower brachial pulse pressure than in the late-onset pre-eclampsia. Furthermore, the mean arterial pressure was higher in early-onset than late onset pre-eclampsia. This suggests that early onset pre-eclampsia is more severe condition than the late-onset pre-eclampsia. In part two, pulse wave velocity remained significantly higher in previously preeclamptic women than non-pregnant controls up to three months after delivery iii (p<0.05).Then it reduced to non significant values. Regional (aortic) arterial stiffness, though it persists for some time after delivery, it is transitory in previously pre-eclamptic women from the rural Africa setting. All blood pressure indices (central and brachial pressures), were increased in women who previously had pre-eclampsia as compared to non pregnant controls up to one year postpartum. Although pulse wave velocity and augmentation decrease to low values with time after delivery increased blood pressure is an indication of compromised arterial compliance in women with previously pre-eclampsia.
- Full Text:
ARTERIAL TONE IN BLACK WOMEN WITH PREECLAMPSIA FROM TRANSKEI REGION OF SOUTH AFRICA
- Authors: AMBROSE VINCENT NAMUGOWA
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2023 , vital:40803 , DOCTOR OF PHILOSOPHY (Ph.D) (In Health Sciences, Physiology)
- Description: Women with pre-eclampsia have an increased risk of cardiovascular disease later in life. The mechanisms which mediate this heightened risk are poorly understood; it was long believed that pre-eclampsia was cured by delivery of the foetus. But it is now apparent that the risks of complications persist for some time after delivery. The aim of the study was to establish the presence and pattern of endothelial dysfunction during gestation and postpartum among women who develop preeclampsia in the Transkei region of South Africa. This was a two parts study: part one was a cross-sectional experimental study, which involved 85 women with established pre-eclampsia (PE) and 112 pregnant controls (PC); part two was a prospective longitudinal study which involved 36 previously pre-eclamptic women and 86 non-pregnant controls (NPC). Maternal wave reflection (augmentation index) and carotid-femoral pulse wave velocity were assessed noninvasively, using applanation tonometry with the SphygmoCor device. Endothelial function was assessed by EndoPAT 2000 device; pneumatic probes were fitted to the index fingers; induced flow-mediated reactive hyperaemia; the ratio of the readings before and after occlusion was then used to calculate the score, the reactive hyperaemia index (RHI) as a measure of endothelial function. In part one, the measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the pregnant control group.PE group compared with pregnant controls, PE had higher median pulse wave velocity [1.2 inter-quartile range (IQR) 1.08-1.35 MoM vs. 0.97, IQR 8.6-1.09 MoM; p=0.0000].In contrast, there were no ii significant differences between the two groups median of central augmentation index (1.0, IQR -0.4 -1.7 MoM vs. 0.9, IQR 0.69-1.36 MoM; p=0.765). RHI was higher in PE than controls (1.16, IQR 1-1.33 MoM vs. 1, IQR 0.9- 1.18 MoM; p=0.0000). Early-onset pre-eclampsia had higher median brachial blood pressure (87.5, IQR 79-101 vs. 82, IQR 65-88 mmHg; p=0.02), higher mean arterial pressure (110, IQR97-120 vs.101 IQR 88-110 mmHg; p=0.04) and higher central diastolic blood pressure (90, IQR 80-103 vs.84, IQR 67-90 mmHg; p=0.017) than the lateonset pre-eclampsia. Pulse wave velocity (carotid-femoral) was increased in pregnant women with preeclampsia during the third trimester. Reactive hyperaemia index, a measure of endothelial function, was higher in pregnant women with pre-eclampsia than pregnant controls. This suggests that regional (aortic) arterial stiffness is increased, but endothelial function, as assessed by ENDOPAT 2000 device, was not compromised in rural African women with pre-eclampsia. Pulse wave reflection, as assessed by augmentation index adjusted to heart rate of 75 beats/min, was increased in women who had early-onset pre-eclampsia more than those with late-onset pre-eclampsia. Brachial diastolic blood pressure was higher in early-onset pre-eclampsia which resulted in lower brachial pulse pressure than in the late-onset pre-eclampsia. Furthermore, the mean arterial pressure was higher in early-onset than late onset pre-eclampsia. This suggests that early onset pre-eclampsia is more severe condition than the late-onset pre-eclampsia. In part two, pulse wave velocity remained significantly higher in previously preeclamptic women than non-pregnant controls up to three months after delivery iii (p<0.05).Then it reduced to non significant values. Regional (aortic) arterial stiffness, though it persists for some time after delivery, it is transitory in previously pre-eclamptic women from the rural Africa setting. All blood pressure indices (central and brachial pressures), were increased in women who previously had pre-eclampsia as compared to non pregnant controls up to one year postpartum. Although pulse wave velocity and augmentation decrease to low values with time after delivery increased blood pressure is an indication of compromised arterial compliance in women with previously pre-eclampsia.
- Full Text:
- Authors: AMBROSE VINCENT NAMUGOWA
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2023 , vital:40803 , DOCTOR OF PHILOSOPHY (Ph.D) (In Health Sciences, Physiology)
- Description: Women with pre-eclampsia have an increased risk of cardiovascular disease later in life. The mechanisms which mediate this heightened risk are poorly understood; it was long believed that pre-eclampsia was cured by delivery of the foetus. But it is now apparent that the risks of complications persist for some time after delivery. The aim of the study was to establish the presence and pattern of endothelial dysfunction during gestation and postpartum among women who develop preeclampsia in the Transkei region of South Africa. This was a two parts study: part one was a cross-sectional experimental study, which involved 85 women with established pre-eclampsia (PE) and 112 pregnant controls (PC); part two was a prospective longitudinal study which involved 36 previously pre-eclamptic women and 86 non-pregnant controls (NPC). Maternal wave reflection (augmentation index) and carotid-femoral pulse wave velocity were assessed noninvasively, using applanation tonometry with the SphygmoCor device. Endothelial function was assessed by EndoPAT 2000 device; pneumatic probes were fitted to the index fingers; induced flow-mediated reactive hyperaemia; the ratio of the readings before and after occlusion was then used to calculate the score, the reactive hyperaemia index (RHI) as a measure of endothelial function. In part one, the measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the pregnant control group.PE group compared with pregnant controls, PE had higher median pulse wave velocity [1.2 inter-quartile range (IQR) 1.08-1.35 MoM vs. 0.97, IQR 8.6-1.09 MoM; p=0.0000].In contrast, there were no ii significant differences between the two groups median of central augmentation index (1.0, IQR -0.4 -1.7 MoM vs. 0.9, IQR 0.69-1.36 MoM; p=0.765). RHI was higher in PE than controls (1.16, IQR 1-1.33 MoM vs. 1, IQR 0.9- 1.18 MoM; p=0.0000). Early-onset pre-eclampsia had higher median brachial blood pressure (87.5, IQR 79-101 vs. 82, IQR 65-88 mmHg; p=0.02), higher mean arterial pressure (110, IQR97-120 vs.101 IQR 88-110 mmHg; p=0.04) and higher central diastolic blood pressure (90, IQR 80-103 vs.84, IQR 67-90 mmHg; p=0.017) than the lateonset pre-eclampsia. Pulse wave velocity (carotid-femoral) was increased in pregnant women with preeclampsia during the third trimester. Reactive hyperaemia index, a measure of endothelial function, was higher in pregnant women with pre-eclampsia than pregnant controls. This suggests that regional (aortic) arterial stiffness is increased, but endothelial function, as assessed by ENDOPAT 2000 device, was not compromised in rural African women with pre-eclampsia. Pulse wave reflection, as assessed by augmentation index adjusted to heart rate of 75 beats/min, was increased in women who had early-onset pre-eclampsia more than those with late-onset pre-eclampsia. Brachial diastolic blood pressure was higher in early-onset pre-eclampsia which resulted in lower brachial pulse pressure than in the late-onset pre-eclampsia. Furthermore, the mean arterial pressure was higher in early-onset than late onset pre-eclampsia. This suggests that early onset pre-eclampsia is more severe condition than the late-onset pre-eclampsia. In part two, pulse wave velocity remained significantly higher in previously preeclamptic women than non-pregnant controls up to three months after delivery iii (p<0.05).Then it reduced to non significant values. Regional (aortic) arterial stiffness, though it persists for some time after delivery, it is transitory in previously pre-eclamptic women from the rural Africa setting. All blood pressure indices (central and brachial pressures), were increased in women who previously had pre-eclampsia as compared to non pregnant controls up to one year postpartum. Although pulse wave velocity and augmentation decrease to low values with time after delivery increased blood pressure is an indication of compromised arterial compliance in women with previously pre-eclampsia.
- Full Text:
EVALUATION OF THE EFFECTIVENESS OF AN OPTICS TEACHING MODULE IN ENHANCING CONCEPTUAL UNDERSTANDING OF GRADE 11 LEARNERS AT A SELECTED SCHOOL IN MTHATHA
- Authors: MERLIN JOHN
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2065 , vital:40812 , DOCTOR OF EDUCATION
- Description: This study aimed at investigating the conceptions and alternative conceptions regarding the optical phenomena ‘reflection’, ‘refraction’ and ‘total internal reflection’ amongst Grade 11 learners at a selected school in Mthatha, Eastern Cape, South Africa and developing remedies to enhance their conceptual understanding of this area. The study adopted a quasi-experimental pre-test – post-test design. To enhance the credibility of the findings of the study, the data were collected using mixed methods (both questionnaires and interviews). The questionnaires developed for the study were 4 tier Optics Diagnostic Instruments (4ODIs) which were designed in such a way that both qualitative and quantitative data could be collected. To explore the findings from the pre-tests, face-to-face interviews with selected learners from both the groups were conducted. This stage was followed by the design an optics teaching module which aimed at enhancing the experimental group learners’ conceptual understanding of the optical phenomena, whereas the comparison group was taught in the traditional teaching method. To test the effectiveness of the designed teaching module, the 4ODIs were administered as post-tests to both groups. To enhance the credibility of the findings from the post-tests, face-to-face interviews were conducted with some selected learners from the experimental group. Since the aim of the interviews at this stage was to test how the designed optics teaching module helped the experimental group learners in enhancing their conceptual understanding, the comparison group learners were not interviewed at this stage since they were taught in the traditional teaching method. The quantitative analyses were carried out using Microsoft Excel and the statistical software, IBM SPSS Version 20. The qualitative analysis was carried out manually by coding and categorizing the learners’ responses from the questionnaires and the interviews. The item analysis of the 1st tiers was carried out using Microsoft Excel. The statistical comparisons of the test scores of the 1st tiers of the tests (pre-test – post-test comparison of both the groups and the experimental group – comparison group comparison of both the pre-tests and the post-tests) were performed using t-tests (independent samples t-test and paired samples t-test). The 2nd tiers (learners’ confidence levels in their responses to the corresponding 1st tiers) and the 4th tiers (learners’ confidence levels in their responses to the corresponding 3rd tiers) were analysed by (using SPSS) calculating measures of central tendencies of their responses. The 3rd tiers (open-ended questions) and the interviews were analysed manually by coding and categorizing learners’ responses. Before the implementation of the optics teaching module, both the experimental and the comparison groups were found to hold a variety of alternative conceptions about the optical phenomena. Moreover, the performances of both the groups were the same. It was also found that the learners from both the groups were not confident when they approached the pre-tests. The qualitative analyses of the learners’ responses to the 3rd tiers and the interviews suggested that most of the correct responses given by the learners to tier-1 of the pre-test questionnaires originated from a faulty or vague understanding of the scientific concepts. Moreover, some of the incorrect responses identified could not be considered as alternative conceptions because of the very low confidence levels the learners displayed in these responses. Such responses were categorized as ‘errors due to lack of knowledge’. The analyses of the post-test questionnaires, and face-to-face interviews conducted immediately after the post-tests, revealed that the experimental group outperformed the comparison group in terms of their conceptual understanding of the optical phenomena. In other words, the number of experimental group learners who held scientifically-accepted concepts increased for some questions of the post-tests and in some other questions, the experimental group learners developed new scientific understanding of many situations with regard to the optical phenomena. To conclude, the findings of the study proved that the Grade 11 learners in the selected school held a variety of alternative conceptions and errors due to lack of knowledge. However, the optics teaching module, which was designed by taking into consideration the learners’ prior knowledge regarding the particular learning area, could remedy most of the alternative conceptions and errors which were merely due to lack of knowledge.
- Full Text:
- Authors: MERLIN JOHN
- Date: 2014
- Language: English
- Type: PhD Manuscript
- Identifier: http://hdl.handle.net/11260/2065 , vital:40812 , DOCTOR OF EDUCATION
- Description: This study aimed at investigating the conceptions and alternative conceptions regarding the optical phenomena ‘reflection’, ‘refraction’ and ‘total internal reflection’ amongst Grade 11 learners at a selected school in Mthatha, Eastern Cape, South Africa and developing remedies to enhance their conceptual understanding of this area. The study adopted a quasi-experimental pre-test – post-test design. To enhance the credibility of the findings of the study, the data were collected using mixed methods (both questionnaires and interviews). The questionnaires developed for the study were 4 tier Optics Diagnostic Instruments (4ODIs) which were designed in such a way that both qualitative and quantitative data could be collected. To explore the findings from the pre-tests, face-to-face interviews with selected learners from both the groups were conducted. This stage was followed by the design an optics teaching module which aimed at enhancing the experimental group learners’ conceptual understanding of the optical phenomena, whereas the comparison group was taught in the traditional teaching method. To test the effectiveness of the designed teaching module, the 4ODIs were administered as post-tests to both groups. To enhance the credibility of the findings from the post-tests, face-to-face interviews were conducted with some selected learners from the experimental group. Since the aim of the interviews at this stage was to test how the designed optics teaching module helped the experimental group learners in enhancing their conceptual understanding, the comparison group learners were not interviewed at this stage since they were taught in the traditional teaching method. The quantitative analyses were carried out using Microsoft Excel and the statistical software, IBM SPSS Version 20. The qualitative analysis was carried out manually by coding and categorizing the learners’ responses from the questionnaires and the interviews. The item analysis of the 1st tiers was carried out using Microsoft Excel. The statistical comparisons of the test scores of the 1st tiers of the tests (pre-test – post-test comparison of both the groups and the experimental group – comparison group comparison of both the pre-tests and the post-tests) were performed using t-tests (independent samples t-test and paired samples t-test). The 2nd tiers (learners’ confidence levels in their responses to the corresponding 1st tiers) and the 4th tiers (learners’ confidence levels in their responses to the corresponding 3rd tiers) were analysed by (using SPSS) calculating measures of central tendencies of their responses. The 3rd tiers (open-ended questions) and the interviews were analysed manually by coding and categorizing learners’ responses. Before the implementation of the optics teaching module, both the experimental and the comparison groups were found to hold a variety of alternative conceptions about the optical phenomena. Moreover, the performances of both the groups were the same. It was also found that the learners from both the groups were not confident when they approached the pre-tests. The qualitative analyses of the learners’ responses to the 3rd tiers and the interviews suggested that most of the correct responses given by the learners to tier-1 of the pre-test questionnaires originated from a faulty or vague understanding of the scientific concepts. Moreover, some of the incorrect responses identified could not be considered as alternative conceptions because of the very low confidence levels the learners displayed in these responses. Such responses were categorized as ‘errors due to lack of knowledge’. The analyses of the post-test questionnaires, and face-to-face interviews conducted immediately after the post-tests, revealed that the experimental group outperformed the comparison group in terms of their conceptual understanding of the optical phenomena. In other words, the number of experimental group learners who held scientifically-accepted concepts increased for some questions of the post-tests and in some other questions, the experimental group learners developed new scientific understanding of many situations with regard to the optical phenomena. To conclude, the findings of the study proved that the Grade 11 learners in the selected school held a variety of alternative conceptions and errors due to lack of knowledge. However, the optics teaching module, which was designed by taking into consideration the learners’ prior knowledge regarding the particular learning area, could remedy most of the alternative conceptions and errors which were merely due to lack of knowledge.
- Full Text:
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