Inaccuracy in landmark identification is regarded as the most important source of error in cephalometry. Better definition of landmarks should therefore contribute to better clinical decisions and research validity. This study primarily comprised of an ex vivo investigation on 50 extracted lower incisor teeth to determine whether radiopaque markers could be utilised to accurately assess lower incisor inclination. Fifty extracted lower incisor teeth were mounted onto a Perspex sheet. Radiopaque markers, manufactured from 1mm wide strips of lead film from used peri-apical radiographs, were attached to the crowns of the mounted teeth. A lateral cephalometric radiograph was taken in accordance to standard radiographic procedures (radiograph A). This showed the true inclination of the teeth. A second radiograph was taken with the roots obscured (radiograph B). Three observers traced the inclinations of the teeth on radiograph B (from incisor edge through the middle of the labio-lingual crown-root junction). The determination was done on two different occasions and the assessments compared with the true inclination. Comparative statistical analysis was applied to the readings and the results indicated that this method compared favourably with other methods to determine incisor inclination. In addition, clinical application of opaque markers to the teeth of patients demonstrated the following: it indicated exactly which tooth was being assessed, provided clear definition of the anatomical crown in the sagittal plane and served as a constant reference point for clinical, study model and cephalometric measurements. decisions and research validity. Opaque radiographic markers on teeth can contribute to more accurate cephalometric measurements in orthodontics, leading to better diagnoses, treatment planning and research validity. / Thesis (MChD (Orthodontics))--University of Pretoria, 2005. / Orthodontics / unrestricted

Un être humain adulte produit environ deux millions d’érythrocytes par seconde, à travers un processus connu sous le nom d’érythropoïèse. L’érythropoïèse est contrôlée par une balance entre prolifération et différenciation finement régulée. L’expression des gènes impliqués dans ces deux processus distincts, est régulée extrinsèquement (cytokines) et intrinsèquement (microenvirennement métabolique, facteurs de transcription). Les facteurs de transcription, fonctionnent sous forme de complexes multiprotéiques et contrôlent l’activité transcriptionnelle des cellules. Parmi eux, le complexe LDB1 joue un rôle clé dans la régulation de la balance prolifération/différenciation pendant l’érythropoïèse, puisqu’il contrôle l’expression des gènes impliquées dans ces deux processus. Au cours de mon doctorat, nous avons d’abord caractérisé les mécanismes moléculaires de la “pré-activation” des gènes de différenciation, également nommés marqueurs erythroides, dans les progéniteurs erythroides immatures. La pré-activation, est un état dans lequel, les gènes sont exprimés à un niveau basal très bas, permissif pour une activation significative pendant la différenciation. Nous avons ainsi montré que les répresseurs : ETO2, IRF2BP2 et NCOR1, interagissent avec le complexe LDB1, et lient ensemble les gènes des marqueurs erythroides et les répriment. Au cours de l’érythropoïèse, ces corépresseurs sont déstabilisés et LDB1 agit alors comme un activateur. En ce qui concerne les gènes de prolifération, nous avons observé que le complexe LDB1 est déstabilisé au niveau de ces loci pendant l’érythropoïèse. Afin d’étudier les mécanismes moléculaires de la répression génique des gènes de prolifération au cours de l’érythropoïèse, nous avons choisi d’étudier Myb, une cible du complexe LDB1, étudié auparavant dans le laboratoire. Nous avons testé trois facteurs : ZEB1, OGT et RNF12, en tant que candidats dans la répression de Myb. Nous avons montré que RNF12 est le seul facteur intervenant dans la transcription de Myb. RNF12 régule Myb probablement par une modification de complexes épigénétiques. / Every second about 2 million erythrocytes are produced in the adult human body, through a process called erythropoiesis. Erythropoiesis is controlled by a highly regulated balance between proliferation and differentiation. Expression of genes responsible for cell proliferation and differentiation is controlled external (such as cytokines) and internal (such as metabolic microenvironment and transcription factors). Transcription factors bind DNA and recruit co-factors generating transcriptional complexes. The LDB1 complex has a key role in the balance between erythroid proliferation vs. differentiation, since it regulates genes involved in both processes. During my Ph.D., we investigated the molecular mechanisms that LDB1 employs to regulate genes with divergent function. We first showed that in erythroid progenitors, differentiating genes, also known as erythroid markers, are primed. Gene priming consists of genes expressed in low basal but significant levels in progenitors, which can rapidly be activated during differentiation. We showed that in progenitors, ETO2, IRF2BP2 and NCOR1, bind the LDB1 complex therefore generating a priming complex. During differentiation, binding of the repressive (ETO2-IRF2BP2-NCOR1) co-factors to the LDB1 complex, is destabilized and genes become active. In genes involved in erythroid proliferation, we observed that LDB1 is destabilized, a feature leading to gene silencing. We used Myb, as a model of gene silencing in the context of regulation by the LDB1 complex. We tested three transcription factors: ZEB1, OGT and RNF12, as candidates in gene silencing. Among these factors, only RNF12 regulates Myb expression, probably through modifications of epigenetic silencers (Polycomb/MLL).

B. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Background: In a group of the elderlies (older person) in Sharpeville, Gauteng, South Africa, the majority live in poverty with a poor nutritional status. This makes them susceptible to develop infectious diseases as well as the risk of Chronic Diseases of the Lifestyle (CDL) such as cancer, diabetes, heart attack, obesity and hypertension. One of the most constant features of aging is the progressively elevated levels of coagulation factors such as FVII, fibrinogen, and impairment of fibrinolysis might play a role in the ageing process. These are associated with increased susceptibility to Cardiovascular diseases (CVD) commonly found. An association between elevated levels of FVII and R353Q polymorphism has been established as a risk factor for CVD. This genetic polymorphism R353Q characterizes the substitution in the exon 8 of the FVII gene of guanine-to-adenine, which results in the replacement of arginine (R) by glutamine (Q) in codon 353 of the F7gene. Objectives: The aim of this study was to evaluate the prevalence of R353Q polymorphism in correlation with haemostatic markers within an urban elderly community in South Africa. Method: This study was ethically approved, and it is an experimental research design on the prevalence of R353Q polymorphism in correlation with homeostatic status (Factor VII, Fibrinogen and PAI-1). The study was done in a black elderly population living in the Vaal triangle region of Sharpeville, attending a day care center, who gave consent to participate in the study. A purposely selected sample of 102 subjects, who met the inclusion criteria were used. The homeostatic status was measured by factor VII and fibrinogen measuring coagulation and PAI-1 measuring fibrinolysis. Results: The prevalence of R353Q genetic polymorphism was established in 14.5% of the sampled population. The prevalence of the RQ (AG) genotype was determined in the sample population with 6.5 % of elevated factor VII levels, 7.8% of increased fibrinogen levels (coagulation) and 10.5 % of decreased levels of PAI-1. The R(A) allele, was detected in 1.3% of the sampled population of normal levels of FVII, fibrinogen and PAI-1. The dominant allele G(Q) was present in 76.3% of the sampled population. An imbalance haemostatic marker was established in the sampled population with 61% of elevated levels of factor VII, 70% of elevated levels of fibrinogen and 88% had a decreased level of PAI-1. Conclusion: The prevalence of R353Q polymorphism was established in this sample population, having an imbalanced haemostatic status of hypercoagulation (factor VII and fibrinogen) and imbalance fibrinolysis (PAI-1), which are strongly associated to CVDs.

The following chapters attempt to show the work that has been done toward restoration, preservation, and marking of historic spots in Texas by patriotic societies, individuals, civic groups, the Centennial Commission, and other agencies. It has not been the purpose of the writer to go into details regarding every one of the sites and individual markers, especially in instances in which several of the same type were erected. In such cases a general description of the markers is given, together with a general idea of the type of inscription that appears on them. Since so much was done by the Centennial Commission, more attention has been devoted to its activities than to those of other organizations unable to carry out such an extensive program...in many instances it has been necessary to rely upon information from magazines, newspapers, Chamber of Commerce bulletins, pamphlets, and personal letters, because of lack of recorded materials. The information obtained, however, has been weighed and carefully compared with other sources on the same subject until its authenticity is assured.

Harbours play a vital role in the economies of most countries since a significant amount of international trade is conducted through them. Ships rely on harbours for the safe loading and unloading of cargo and the harbour infrastructure relies on breakwaters for protection. As a result, the design and analysis of breakwaters receives keen interest from the engineering community. Coastal engineers need an easy-to-use tool that can model the way in which waves interact with large numbers of interlocking armour units. Although the study of fluid–structure interaction generates a lot of research activity, none of the reviewed literature describes a suitable method of analysis. The goal of the research was to develop a simulation algorithm that meets all the criteria by allowing CFD software and physics middleware to work in unison. The proposed simulation algorithm used Linux “shell scripts” to coordinate the actions of commercial CFD software (Star-CCM+) and freely available physics middleware (PhysX). The CFD software modelled the two-phase fluid and provided force and moment data to the physics middleware so that the movement of the armour units could be determined. The simulation algorithm was verified numerically and experimentally. The numerical verification exercise was of limited value due to unresolved issues with the CFD software chosen for the analysis, but it was shown that PhysX responds appropriately given the correct force data as input. Experiments were conducted in a hydraulics laboratory to study the interaction of a solitary wave and cubes stacked on a platform. Fiducial markers were used to track the movement of the cubes. The phenomenon of interest was the transfer of momentum from the wave to the rigid bodies, and the results confirmed that the effect was captured adequately. The study concludes with suggestions for further study. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Harbours play a vital role in the economies of most countries since a significant amount of international trade is conducted through them. Ships rely on harbours for the safe loading and unloading of cargo and the harbour infrastructure relies on breakwaters for protection. As a result, the design and analysis of breakwaters receives keen interest from the engineering community. Coastal engineers need an easy-to-use tool that can model the way in which waves interact with large numbers of interlocking armour units. Although the study of fluid–structure interaction generates a lot of research activity, none of the reviewed literature describes a suitable method of analysis. The goal of the research was to develop a simulation algorithm that meets all the criteria by allowing CFD software and physics middleware to work in unison. The proposed simulation algorithm used Linux “shell scripts” to coordinate the actions of commercial CFD software (Star-CCM+) and freely available physics middleware (PhysX). The CFD software modelled the two-phase fluid and provided force and moment data to the physics middleware so that the movement of the armour units could be determined. The simulation algorithm was verified numerically and experimentally. The numerical verification exercise was of limited value due to unresolved issues with the CFD software chosen for the analysis, but it was shown that PhysX responds appropriately given the correct force data as input. Experiments were conducted in a hydraulics laboratory to study the interaction of a solitary wave and cubes stacked on a platform. Fiducial markers were used to track the movement of the cubes. The phenomenon of interest was the transfer of momentum from the wave to the rigid bodies, and the results confirmed that the effect was captured adequately. The study concludes with suggestions for further study. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Thesis (PhDAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Maize is undoubtedly South Africa's most important field crop. The identification of markers and genes for traits of interest is important to sustain the improvement of maize cultivation. Northern corn leaf blight (NClB) is a disease that occurs worldwide and can dramatically reduce yield. A number of single dominant resistance genes have been identified for NClB and some have been mapped. Currently there are no simple PCR markers for any of these resistance genes, making markerassisted selection (MAS) difficult. The aim of this study was to develop PCR markers for the NClB resistance genes Ht1, Ht2, Ht3 and Htn1 in maize. To accomplish this, the AFlP (amplified fragment length polymorphism) technique was first optimised. The results indicated that the Mlul/Msel restriction enzyme combination produces a higher percentage of polymorph isms when compared to the PstllMsel enzyme combination. It was also shown that the enzyme combination plays an important role in the percentage of polymorphic fragments observed, whereas the number of restriction enzymes used in AFlP analysis only significantly affects the total number of fragments scored. Populations segregating for the different resistance genes were not available for this study. Nearly-isogenic lines (Nils) were used in combination with AFlP technology to identify markers that map close to the genes. AFlP markers common in at least two resistant or susceptible lines were cloned and converted to PCR markers. Two commercially available recombinant inbred line (Ril) populations were then used to map the identified markers. For Htn1 fifteen polymorphic fragments were present in both resistant lines. They were selected for sequence specific marker conversion. Seven of the fifteen sequence characterized amplified region (SCAR) markers were polymorphic on the Nil pairs and five mapped to one region of maize chromosome 8.05/06. Twenty-one AFlP markers were identified for Ht1 and four SCAR markers were polymorphic In the Ht1 Nils. Three of these were mapped to chromosome 2.07. Three AFlP markers were identified for Ht2 of which two were converted to SCAR markers. Both SCAR markers were polymorphic on the Ht2 Nils and mapped to chromosome 8.05/06. On the Ht3 NILs, four AFLP markers were identified and two converted SCAR markers and one microsatellite marker (bnlg1666) were polymorphic. One of the SCAR markers and the microsatellite marker were mapped to chromosome 7.04 using a RIL population. This reports the first tentative mapping position for the Ht3 locus. The next step was to determine if a set of marker alleles could be used in a number of Htn 1 resistance lines to identify a common donor region selected by the breeders. Nine markers consisting of five SCAR markers, three converted RFLP markers and one microsatellite marker were used on 16 Htn1 resistant lines. The marker allele of us3 was in 12 of the 16 lines in coupling with Htn1 resistance. Second was the marker us5 in 11 of the 16 lines. Using this data 14 of the 16 lines shared a common introgressed region between the markers us3 and us5. A further common introgressed region between 11 of the inbred lines was found between the markers us14 and asg17. The last aim of this study was to propose a new marker technique that might be more successful than the AFLP technique in the identification of markers closely linked to genes. A new marker approach was identified where a MITE (Hbr) primer was used as an anchor primer in combination with resistance gene analog primers. This was found to be a highly polymorphic marker technique that could be used to identify markers and possibly candidate genes. It is a robust technique, which is affordable since amplifications occur from undigested genomic DNA and the primers mainly amplify fragments from genic regions. / AFRIKAANSE OPSOMMING: Mielies (Zea mays) is ongetwyfeld Suid Afrika se belangrikste lanbou gewas. Vir volgehoue opbrengs verbetering is die identifisering van merkers en gene vir belangrike eienskappe noodsaaklik. Noordelike blaarskroei (NBS) kan opbrengs wesenlik kan beïnvloed. Tans is daar reeds "n aantal enkel weerstandsgene geïdentifiseer, maar geen PKR-merkers is beskikbaar vir merker gebaseerde seleksie nie. Die doelwit van hierdie studie was om PKR-merkers te ontwikkel vir vier enkel weerstands gene (Ht1, Ht2, Ht3 en Htn1) teen NBS in mielies. Om die doelstelling te bereik is die AFLP-tegniek eers geoptimiseer. Op grond van waargenome aantal polimorfismes, was Mlul/Mse/"n beter restriksie ensiem kombinasie as Pstl/Msel. In die studie is ook bewys dat die aantal (meer as twee) restriksie ensieme wat gebruik word slegs die aantal fragmente, en nie die persentasie polimorfismes, wesenlik beïnvloed nie. Geen segregerende populasie was vir die verskillende gene beskikbaar nie. Naby isogeniese lyne (NILe) is daarom in kombinasie met die AFLP-tegniek gebruik om merkers te identifiseer wat naby die gene karteer. Alleenlik polimorfiese merkers wat in ten minste twee weerstand biedende of vatbare lyne voorgekom het, is gekloneer en omgeskakel na PKR-merkers. Daarna is twee kommersiële rekombinante ingeteelde lyn populasies gebruik om die gene te karteer. Vyftien fragmente is gevind wat gekoppel was met die Htn1 weerstand. Sewe van hierdie merkers is omgeskakel in polimorfiese SCAR-merkers waarvan vyf gekarteer is in een gebied op chromosoom 8.05/06. Een-en-twintig AFLP-merkers is geïndentifiseer vir Ht1 en vier is omgeskakel na polimorfiese SCAR-merkers. Drie hiervan is gekarteer op chromosoom 2.07. Drie AFLP-merkers is geïndetifiseer vir Ht2 waarvan 2 omgeskakel is na polimorfiese SCAR-merkers. Altwee hierdie merkers is gekarteer op chromosoom 8.05/06. Op die Ht3 lyne is vier AFLP-merkers geïdentifiseer waarvan twee omgeskakel is na polimorfiese SCAR-merkers. Een mikrosatelliet merker (bnlg1666) is ook gevind wat die selfde polimorfiese patroon wys op die Ht3 lyne. Die mikrosateliet en een van die SCAR-merkers het gekarteer op chromosomale posisie 7.04. Hierdie is die eerste tentatiewe posisie vir die Ht3 lokus. Die volgende stap was om te bepaal of "n stel polimorfiese merker-allele gebruik kan word om die donor DNA-segment te identifiseer wat die plantteiers geselekteer het. Nege PKR-merkers wat bestaan het uit vyf SCAR-merkers, 3 omgeskakelde RFLP merkers en een mikrosateliet is gebruik op 16 Hnt1 weerstandslyne. Us3 was die merker alleel wat in die meeste gevalle gekoppel was met die Htn1 weerstandslyne (12/16). Tweede was die merker us5 (in 11 van die 16 lyne). Uit die data blyk dit dat 14 van die 16 lyne "n donor segment het wat beide merkers us3 en us5 bevat. Merkers us14 en asg17 het in 11 van die 16 bestande lyne saam voorgekom. Die laaste doelstelling van hierdie studie was om "n nuwe tegniek te ontwikkel wat dalk meer suksesvol as AFLPs kan wees om merkers te identifiseer nabyaan gene. "n Nuwe tegniek word voorgestel waar "n MITE (Hbr) inleier gebruik kan word in kombinasie met weerstandgeen-analoog inleiers. Dit is gevind dat hierdie kombinasie van inleiers "n hoogs polimorfiese band patroon gee en dat die merkers ook dalk kandidaat-gene kan wees. Die tegniek is maklik uitvoerbaar, relatief goedkoop en maak gebruik van onverteerde genomiese DNA. Die fragmente wat geamplifiseer word is hoofsaaklik vanaf geenryke areas.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

published_or_final_version / Surgery / Doctoral / Doctor of Philosophy