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A comparative analysis of the cost-based and simplified upper limit approaches for calculating analytical threshold in support of forensic DNA short tandem repeat analysisGordon, Daniel Bernard 01 February 2023 (has links)
The determination and application of Analytical Threshold (AT) is a vital part of the forensic Deoxyribonucleic Acid (DNA) internal validation process. AT is the relative fluorescence unit (RFU) signal at which allelic peaks can be confidently distinguished from baseline noise. Several methods of calculating AT are currently being implemented within the forensic DNA community. These methods may utilize DNA negative sample data, DNA positive sample data, or both in their calculations. In this study, two of the DNA positive-based AT calculation techniques were chosen for assessment and comparison. The simplified upper limit approach (ULA) and the cost-based approach. ATs were calculated for each dye channel using a dilution series of 3 single source DNA samples ranging from 0.05-0.8ng. The ATs calculated via the cost-based approach consistently exhibited lower values than those determined via the ULA. As a result, the incidence of allelic drop-out exhibited by these AT values was also consistently lower, with an equivalent or only marginally increased incidence of baseline noise drop-in. These results indicated that the cost-based approach may be a more effective and practical method of calculating AT than the ULA, particularly in the analysis of low DNA template samples.
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Development and validation of Non-CODIS miniSTR genotyping systems suitable for forensic case work in South AfricaAbrahams Zainonesa January 2010 (has links)
<p>The objective of this study was to develop and validate a six Non-CODIS miniSTR genotyping system and to determine its suitability for forensic casework in South Africa. In Non-CODIS miniSTR genotyping systems, smaller PCR products are amplified and the primers are positioned as close as possible to the repeat region. For this reason, these systems can be valuable in a variety of scenarios including complex paternity cases, missing persons work, and mass fatality disasters.</p>
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Genetic diversity of the Organic Cation Transporter 1 gene within the Cape Coloured PopulationBrendon Pearce January 2012 (has links)
<p>The aim of this study was to investigate the genetic diversity of the SLC22A1 gene and to deduce its possible pharmacogenetic implications within the Cape Coloured population of South  / Africa / a uniquely admixed population of immigrant Europeans, Asians and the indigenous populations. Recent studies have reported an abundance of polymorphic variants within this solute  / carrier transporter gene encoding for the organic cation transporter 1, as well as evidence linking these variants to an effect on metformin uptake. This study included establishing baseline  / frequency distribution of previously reported alleles for 20 SNP variants within the SLC22A1 gene, as well as the development of SNaPshot® / and Multiplex AS-PCR genotyping assays, and  / also exploring the possibility of using High-resolution melt (HRM) analysis as a costeffective alternative for SNP genotyping. Ethics clearance was obtained from the Ethics Committee of the  / University of the Western Cape. Biological samples in the form of buccal (oral) swabs were collected from 132 unrelated voluntary donors from the Cape Coloured population residing in the  / Cape Metropolitan area. Two SNaPshot® / Multiplex Systems were specifically designed for the study,successfully optimized and used for genotyping. Hundred genetic profiles were then generated for a total of 20 SNP variants on SLC22A1 gene, using this primer extension-based genotyping method that enables multiplexing up 10 SNPs. Population genetics data obtained for  / the investigated SNPs were analysed using various statistical analysis software. Important population genetic parameters were calculated, and possible pharmacogenetics implications were then discussed. Among others, allelic and genotypic frequencies, as well as linkage disequilibrium were determined and compared with world populations. Minor deviation from Hardy- Weinberg equilibrium was observed in the Cape Coloured population. No significantLinkage Disequilibrium between the investigated SNPs was observed in this population. A Multiplex allele specific &ndash / PCR (MAS-PCR) genotyping  / system was successfully designed and optimized for the genotyping of 10 SNPs from the SLC22A1. This system, also developed specifically for this study, was made of 2 multiplexes each covering 5 SNPs. It is an inexpensive genotyping assay that allows for efficient discrimination of SNP polymorphisms in one reaction tube with standard PCR conditions. A pilot study was  / conducted to explore the possibility of using High-resolution melt (HRM) analysis as a cost-effective alternative for SNP genotyping. In addition to genotyping, HRM analysis can be used to scan  / large numbers of samples for novel genetic variations.  / </p>
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Development and validation of Non-CODIS miniSTR genotyping systems suitable for forensic case work in South AfricaAbrahams Zainonesa January 2010 (has links)
<p>The objective of this study was to develop and validate a six Non-CODIS miniSTR genotyping system and to determine its suitability for forensic casework in South Africa. In Non-CODIS miniSTR genotyping systems, smaller PCR products are amplified and the primers are positioned as close as possible to the repeat region. For this reason, these systems can be valuable in a variety of scenarios including complex paternity cases, missing persons work, and mass fatality disasters.</p>
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Genetic diversity of the Organic Cation Transporter 1 gene within the Cape Coloured PopulationBrendon Pearce January 2012 (has links)
<p>The aim of this study was to investigate the genetic diversity of the SLC22A1 gene and to deduce its possible pharmacogenetic implications within the Cape Coloured population of South  / Africa / a uniquely admixed population of immigrant Europeans, Asians and the indigenous populations. Recent studies have reported an abundance of polymorphic variants within this solute  / carrier transporter gene encoding for the organic cation transporter 1, as well as evidence linking these variants to an effect on metformin uptake. This study included establishing baseline  / frequency distribution of previously reported alleles for 20 SNP variants within the SLC22A1 gene, as well as the development of SNaPshot® / and Multiplex AS-PCR genotyping assays, and  / also exploring the possibility of using High-resolution melt (HRM) analysis as a costeffective alternative for SNP genotyping. Ethics clearance was obtained from the Ethics Committee of the  / University of the Western Cape. Biological samples in the form of buccal (oral) swabs were collected from 132 unrelated voluntary donors from the Cape Coloured population residing in the  / Cape Metropolitan area. Two SNaPshot® / Multiplex Systems were specifically designed for the study,successfully optimized and used for genotyping. Hundred genetic profiles were then generated for a total of 20 SNP variants on SLC22A1 gene, using this primer extension-based genotyping method that enables multiplexing up 10 SNPs. Population genetics data obtained for  / the investigated SNPs were analysed using various statistical analysis software. Important population genetic parameters were calculated, and possible pharmacogenetics implications were then discussed. Among others, allelic and genotypic frequencies, as well as linkage disequilibrium were determined and compared with world populations. Minor deviation from Hardy- Weinberg equilibrium was observed in the Cape Coloured population. No significantLinkage Disequilibrium between the investigated SNPs was observed in this population. A Multiplex allele specific &ndash / PCR (MAS-PCR) genotyping  / system was successfully designed and optimized for the genotyping of 10 SNPs from the SLC22A1. This system, also developed specifically for this study, was made of 2 multiplexes each covering 5 SNPs. It is an inexpensive genotyping assay that allows for efficient discrimination of SNP polymorphisms in one reaction tube with standard PCR conditions. A pilot study was  / conducted to explore the possibility of using High-resolution melt (HRM) analysis as a cost-effective alternative for SNP genotyping. In addition to genotyping, HRM analysis can be used to scan  / large numbers of samples for novel genetic variations.  / </p>
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Development and validation of a non- CODIS miniSTR genotyping system suitable for forensic case work in South AfricaAbrahams, Zainonesa January 2010 (has links)
The objective of this study was to develop and validate a six Non-CODIS miniSTR
genotyping system and to determine its suitability for forensic casework in South Africa.In Non-CODIS miniSTR genotyping systems, smaller PCR products are amplified and the primers are positioned as close as possible to the repeat region. For this reason, these systems can be valuable in a variety of scenarios including complex paternity cases,missing persons work, and mass fatality disasters.
After the successful implementation of the genotyping system in the laboratory, allele size range was determined for each of the loci and allelic ladders were constructed. The entire repeat regions of the six loci under investigation were successfully sequenced.Consequently, allele repeat number, structure and observed size were determined for each locus.An internal validation study of the six Non-CODIS miniSTR genotyping system was conducted following the SWGDAM guidelines. A comprehensive population study,covering five population groups from South Africa was also carried out.The genotyping system produced consistent, accurate and precise genetic profiles for low concentrations of template DNA. When analyzing mixed DNA samples, successful differentiation of minor and major DNA components was identifiable. Amplification products were observed in non-human DNA studies but in all instances complete genotype profiles were not obtained.
Allele frequencies and forensic parameters were determined for the system in five South African population groups (i.e. Afrikaner, Asian-Indian, Mixed Ancestry, Xhosa and Cape Muslim). No deviation from Hardy-Weinberg equilibrium was observed in any of the populations. Furthermore, all populations displayed a high power of discrimination and a high power of exclusion.The six Non-CODIS miniSTR genotyping system has shown a good potential to aid in the analysis of degraded DNA samples. This system can be further improved by including additional loci. Even in its current form, it can certainly provide additional discrimination in complex paternity and/or missing person cases. / >Magister Scientiae - MSc
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Development and validation of Non-CODIS miniSTR genotyping systems suitable for forensic case work in South AfricaAbrahams, Zainonesa January 2010 (has links)
Magister Scientiae - MSc / The objective of this study was to develop and validate a six Non-CODIS miniSTR genotyping system and to determine its suitability for forensic casework in South Africa. In Non-CODIS miniSTR genotyping systems, smaller PCR products are amplified and the primers are positioned as close as possible to the repeat region. For this reason, these systems can be valuable in a variety of scenarios including complex paternity cases, missing persons work, and mass fatality disasters. / South Africa
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Genetic diversity of the Organic Cation Transporter 1 gene within the Cape Coloured PopulationPearce, Brendon January 2012 (has links)
Magister Scientiae - MSc / The aim of this study was to investigate the genetic diversity of the SLC22A1 gene and to deduce its possible pharmacogenetic implications within the Cape Coloured population of South Africa; a uniquely admixed population of immigrant Europeans, Asians and the indigenous populations. Recent studies have reported an abundance of polymorphic variants within this solute carrier transporter gene encoding for the organic cation transporter 1, as well as evidence linking these variants to an effect on metformin uptake. This study included establishing baseline frequency distribution of previously reported alleles for 20 SNP variants within the SLC22A1 gene, as well as the development of SNaPshot® and Multiplex AS-PCR genotyping assays, and also exploring the possibility of using High-resolution melt (HRM) analysis as a costeffective alternative for SNP genotyping. Ethics clearance was obtained from the Ethics Committee of the University of the Western Cape. Biological samples in the form of buccal (oral) swabs were collected from 132 unrelated voluntary donors from the Cape Coloured population residing in the Cape Metropolitan area. Two SNaPshot® Multiplex Systems were specifically designed for the study,successfully optimized and used for genotyping. Hundred genetic profiles were then generated for a total of 20 SNP variants on SLC22A1 gene, using this primer extension-based genotyping method that enables multiplexing up 10 SNPs. Population genetics data obtained for the investigated SNPs were analysed using various statistical analysis software. Important population genetic parameters were calculated, and possible pharmacogenetics implications were then discussed. Among others, allelic and genotypic frequencies, as well as linkage disequilibrium were determined and compared with world populations. Minor deviation from Hardy- Weinberg equilibrium was observed in the Cape Coloured population. No significantLinkage Disequilibrium between the investigated SNPs was observed in this population. A Multiplex allele specific – PCR (MAS-PCR) genotyping system was successfully designed and optimized for the genotyping of 10 SNPs from the SLC22A1. This system, also developed specifically for this study, was made of 2 multiplexes each covering 5 SNPs. It is an inexpensive genotyping assay that allows for efficient discrimination of SNP polymorphisms in one reaction tube with standard PCR conditions. A pilot study was conducted to explore the possibility of using High-resolution melt (HRM) analysis as a cost-effective alternative for SNP genotyping. In addition to genotyping, HRM analysis can be used to scan large numbers of samples for novel genetic variations. / South Africa
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Benefits of Pharmacometric Model-Based Design and Analysis of Clinical TrialsKarlsson, Kristin E January 2010 (has links)
Quantitative pharmacokinetic-pharmacodynamic and disease progression models are the core of the science of pharmacometrics which has been identified as one of the strategies that can make drug development more effective. To adequately develop and utilize these models one needs to carefully consider the nature of the data, choice of appropriate estimation methods, model evaluation strategies, and, most importantly, the intended use of the model. The general aim of this thesis was to investigate how the use of pharmacometric models can improve the design and analysis of clinical trials within drug development. The development of pharmacometric models for clinical assessment scales in stroke and graded severity events, in this thesis, show the benefit of describing data as close to its true nature as possible, as it increases the predictive abilities and allows for mechanistic interpretations of the models. Performance of three estimation methods implemented in the mixed-effects modeling software NONMEM; 1) Laplace, 2) SAEM, and 3) Importance sampling, applied when modeling repeated time-to-event data, was investigated. The two latter methods are to be preferred if less than approximately half of the individuals experience events. In addition, predictive performance of two validation procedures, internal and external validation, was explored, with internal validation being preferred in most cases. Model-based analysis was compared to conventional methods by the use of clinical trial simulations and the power to detect a drug effect was improved with a pharmacometric design and analysis. Throughout this thesis several examples have shown the possibility of significantly reducing sample sizes in clinical trials with a pharmacometric model-based analysis. This approach will reduce time and costs spent in the development of new drug therapies, but foremost reduce the number of healthy volunteers and patients exposed to experimental drugs.
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Etude de la qualité géomorphologique de modèles numériques de terrain issus de l’imagerie spatiale / Study on the geomorphological quality of digital terrain models derived from space imageryHage, Mhamad El 12 November 2012 (has links)
La production de Modèles Numériques de Terrain (MNT) a subi d’importantes évolutions durant les deux dernières décennies en réponse à une demande croissante pour des besoins scientifiques et industriels. De nombreux satellites d’observation de la Terre, utilisant des capteurs tant optiques que radar, ont permis de produire des MNT couvrant la plupart de la surface terrestre. De plus, les algorithmes de traitement d’images et de nuages de points ont subi d’importants développements. Ces évolutions ont fourni des MNT à différentes échelles pour tout utilisateur. Les applications basées sur la géomorphologie ont profité de ces progrès. En effet, ces applications exploitent les formes du terrain dont le MNT constitue une donnée de base. Cette étude a pour objectif d’évaluer l’impact des paramètres de production de MNT par photogrammétrie et par InSAR sur la qualité de position et de forme de ces modèles. La qualité de position, évaluée par les producteurs de MNT, n’est pas suffisante pour évaluer la qualité des formes. Ainsi, nous avons décrit les méthodes d’évaluation de la qualité de position et de forme et la différence entre elles. Une méthode originale de validation interne, qui n’exige pas de données de référence, a été proposée. Ensuite, l’impact des paramètres de l’appariement stéréoscopique, du traitement interférométrique ainsi que du rééchantillonnage, sur l’altitude et les formes, a été évalué. Finalement, nous avons conclu sur des recommandations pour choisir correctement les paramètres de production, en particulier en photogrammétrie.Nous avons observé un impact négligeable de la plupart des paramètres sur l’altitude, à l’exception de ceux de l’InSAR. Par contre, un impact significatif existe sur les dérivées de l’altitude. L’impact des paramètres d’appariement présente une forte dépendance avec la morphologie du terrain et l’occupation du sol. Ainsi, le choix de ces paramètres doit être effectué en prenant en considération ces deux facteurs. L’effet des paramètres du traitement interférométrique se manifeste par des erreurs de déroulement de phase qui affectent principalement l’altitude et peu les dérivées. Les méthodes d’interpolation et la taille de maille présentent un impact faible sur l’altitude et important sur ses dérivées. En effet, leur valeur et leur qualité dépendent directement de la taille de maille. Le choix de cette taille doit s’effectuer selon les besoins de l’application visée. Enfin, nous avons conclu que ces paramètres sont interdépendants et peuvent avoir des effets similaires. Leur choix doit être effectué en prenant en considération à la fois l’application concernée, la morphologie du terrain et son occupation du sol afin de minimiser l’erreur des résultats finaux et des conclusions. / The production of Digital Elevation Models (DEMs) has undergone significant evolution duringthe last two decades resulting from a growing demand for scientific as well as industrial purposes.Many Earth observation satellites, using optical and radar sensors, have enabled the production ofDEMs covering most of the Earth’s surface. The algorithms of image and point cloud processing havealso undergone significant evolution. This progress has provided DEMs on different scales, which canfulfill the requirements of many users. The applications based on geomorphology have benefitted fromthis evolution. Indeed, these applications concentrate specifically on landforms for which the DEMconstitutes a basic data.The aim of this study is to assess the impact of the parameters of DEM production byphotogrammetry and InSAR on position and shape quality. The position quality, assessed by DEMproducers, is not sufficient for the evaluation of shape quality. Thus, the evaluation methods ofposition and shape quality and the difference between them are described. A novel method of internalvalidation, which does not require reference data, is proposed. Then, the impact of image matchingand interferometric processing parameters as well as resampling, on elevation and shapes, is assessed.Finally, we conclude on recommendations on how to choose the production parameters correctly,particularly for photogrammetry.We observe little impact from most of the parameters on the elevation, except InSAR parameters.On the other hand, there is a significant impact on the elevation derivatives. The impact of matchingparameters presents a strong dependence on the terrain morphology and the landcover. Therefore,these parameters have to be selected by taking into account these two factors. The effect ofinterferometric processing manifests by phase unwrapping errors that mainly affect the elevation andless the derivatives. The interpolation methods and the mesh size present a small impact on theelevation and a significant impact on the derivatives. Indeed, the value of the derivatives and theirquality depend directly on the mesh size. The selection of this size has to be made according to theforeseen application. Finally, we conclude that these parameters are interdependent and can havesimilar effects. They must be selected according to the foreseen application, the terrain morphologyand the landcover in order to minimize the error in the final results and the conclusions.
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