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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Potentiel et limites de l’approximation faciale forensique sur un crâne sec assistée par le phénotypage d’ADN

Durand-Guévin, Ariane 08 1900 (has links)
La reconstruction faciale permet d’approximer un visage sur la base d’un crâne, lorsque des restes humains sont retrouvés. En science forensique, elle est l’un des outils utilisés dans un but d’identification post-mortem. Les procédures actuelles d’approximation ne sont pas standardisées et constamment revisitées. Il est également possible d’obtenir des prédictions du phénotype d’un individu (caractères physiques apparents) à partir de son ADN, qui pourraient être ajoutées aux reconstructions pour maximiser les chances de reconnaissance. Cette recherche vise à étudier l’approximation faciale à des fins de reconnaissance et l’apport du phénotypage par l’ADN à cette pratique. Le crâne et le relevé biologique d’un donneur du laboratoire d’anatomie de l’UQTR ont été utilisés. Six praticiens ont approximé son visage à partir d’une copie de son crâne et de ses données phénotypiques et anthropologiques. Les résultats corroborent qu’il existe un manque de standardisation des méthodes et techniques, menant à différents résultats selon le praticien. Des tests de reconnaissance et de ressemblance ont été effectués à l’aide d’un échantillon de 46 participants. Malgré la variabilité des approximations, elles ont toutes été reconnues au moins une fois lors des tests de reconnaissance, soulevant la possibilité que la reconnaissance d’un visage est idiosyncratique. Les caractéristiques qui semblent influencer davantage la reconnaissance sont la forme, la taille et la position des yeux, de la bouche et du nez. Finalement, au regard des incertitudes propres à la méthode et du rôle investigatif de l’approximation faciale, il est recommandé que le phénotypage accompagne l’accompagne par écrit. / Facial reconstruction is a process by which a face is approximated from a skull when human remains are found. In forensic science, it is one of the many tools used for the purpose of post-mortem identification. The current approximation procedures are not standardized and are always revisited. Nowadays, it is possible to obtain phenotype (apparent physical traits) predictions from an individual’s DNA. These predictions could be added to facial approximations to maximize the chances of recognition. This research aims to study facial approximation for recognition purposes and the plus-value of DNA phenotyping to facial approximation. The skull and biological material from one donor of the UQTR’s anatomy laboratory were used. Six practitioners approximated the donor’s face using a copy of his skull, and phenotyping and anthropological data. The results corroborated the lack of standardization regarding the approximating methods and techniques, which leads to different resulting approximations depending on the practitioner. Recognition and resemblance tests were carried out with a sample of 46 participants. Despite the wide variability of the approximations, they were all recognized at least once during the recognition tests, raising the possibility that the recognition of a face is idiosyncratic. The characteristics that seemed the most important to recognition were the shape, size and position of the eyes, the mouth, and the nose. Finally, with regard to the uncertainties specific to the method and the final investigative role of facial approximation, phenotyping would benefit in feeding a spoken portrait.
62

Forensic taphonomy : investigating the post mortem biochemical properties of cartilage and fungal succession as potential forensic tools

Bolton, Shawna N. January 2015 (has links)
Post mortem interval (PMI – the time elapsed since death and discovery) is important to medicolegal investigations. It helps to construct crucial time lines and assists with the identification of unknown persons by inclusion or exclusion of a suspect’s known movements. Accurate methodologies for establishing PMI are limited to about 48-hours. Such methods involve use of increasing levels of potassium in vitreous humour, and algor mortis. This study is two-fold. Firstly, it explores the biomolecular changes in degrading porcine cartilage buried in soil environments and its potential to determine PMI in the crucial two days to two months period. Trotters were interred in a number of graves at two distinct locations exhibiting dissimilar soil environments. Weekly disinterments (for 6 weeks) resulted in dissection for cartilage samples which were processed for protein immunoblot analyses and cell vitality assays. Results demonstrate that aggrecan, a major structural proteoglycan, produces high (230kDa) and low (38kDa) molecular weight cross-reactive polypeptides (CRPs) within cartilage extracellular matrix. The 230kDa CRP degrades in a reproducible manner irrespective of the different soil environments utilised. As PMI increases, aggrecan diminishes and degrades forming heterogeneous subpopulations with time. Immunodetection of aggrecan ceases when joint exposure to the soil environment occurs. At this time, aggrecan is metabolised by soil microbes. The molecular breakdown of cartilage proteoglycans has potential for use as a reliable indicator of PMI, irrespective of differing soil environments, beyond the 48-hours period. Likewise, vitality assays also demonstrated viable chondrocytes for as long as 35 PM days. The second component of this study examined the fungal activity associated with trotters buried below ground. Results indicate that fungal growth was considerably influenced by soil chemistry and changes in the environment. Fungal colonisation did not demonstrate temporal patterns of succession. The results of this study indicate that cartilage has the potential to prolong PMI determination well beyond the current 48- and 100-hour limitations posed by various other soft tissue methods. Moreover, the long-term post mortem viability of chondrocytes presents an opportunity to explore DNA extraction from these cells for the purpose of establishing a positive identification for unidentified remains. On the contrary, the growth and colonisation patterns of post putrefactive fungi in relation to decomposing porcine trotters proved to be futile for estimating PMI. Therefore, fungi may not be a suitable candidate for evaluating PMI during the early phase fungal activity.
63

An assessment of disease on the health of green (Chelonia mydas) and loggerhead (Caretta caretta) turtles in southern Queensland Australia

Mark-Shannon Flint Unknown Date (has links)
Marine turtle numbers are in a state of flux around the world. Six of the seven remaining species of these long-lived animals are threatened; with the seventh being listed data deficient. Reasons for these fluctuations are speculated to be due to human related impacts (direct) and increase in disease occurrence caused by changes in the natural environment (indirect). Most direct impacts have been identified and strategies implemented to mitigate their effects with varying degrees of success; however the indirect effects on marine animals remain an understudied area. This thesis outlined the development of ante- and post-mortem diagnostic techniques to identify prevalent diseases affecting two marine turtle species in southern Queensland over a four year (2006-2009) period. This data was used to determine the impact of disease on turtle survivorship. Two-hundred and ninety green turtles (Chelonia mydas) from Moreton and Shoalwater Bays were captured, clinically assessed and blood sampled. Clinically healthy animals (n = 211) were used to derive biochemical and haematological reference intervals using two methods. Comparisons with clinically unhealthy animals (n = 25) indicated all unhealthy animals had at least some plasma biochemical and haematological values outside the derived intervals (albumin, 48% of unhealthy animals; alkaline phosphatase (ALP), 35%; aspartate transaminase (AST), 13%; creatinine, 30%; globulin, 3%; glucose, 34%; lactic dehydrogenase (LDH), 26%; phosphorus, 22%; sodium, 13%; thrombocytes, 57%; and monocytes, 5%). Amongst small immature animals, those with Chelonibia testudinaria plastron barnacle counts of at least 20 were approximately three times more likely to be unhealthy than turtles with no barnacles. In addition, small immature and mature turtles were more likely to be unhealthy than large immature turtles (Chapter 2). By the same method, 101 loggerhead turtles (Caretta caretta) in Moreton Bay were assessed and bled. Clinically healthy animals (n = 63) were used to derive intervals. Comparisons with clinically unhealthy animals (n = 23) indicated 82% and 45% had at least one biochemical and hematological result, respectively, outside of at least one of the calculated intervals. Neither sex nor maturity (mature versus large immature) influenced the risk of being clinically unhealthy (Chapter 3). A standardised approach to post-mortem examination of marine turtles for veterinary clinicians with a concurrent descriptive review of gross and microscopic pathological lesions commonly seen during examination in Australia (Chapter 4) was used to accurately determine diseases and causes of death in 100 green turtles submitted from various regions of southern Queensland for examination. Spirorchiid parasitism was found to be the most frequently occurring cause of mortality (41.8%), followed by gastrointestinal impaction (11.8%), microbiological infectious diseases (5.2%) and trauma (5.2%). Spirorchiid parasitism with associated inflammation (75%) was the most frequently occurring disease followed by gastrointestinal impaction (5.1%). Season and turtle age had limited influences on disease. Severity of spirorchiidiasis in the brain was independent of severity in other organs (Chapter 5). From these examinations, the most prevalent disease syndrome (spirorchiidiasis) and a previously unreported finding in Australian waters (corneal fibropapillomatosis) were selected to be examined in greater detail. Spirorchiid parasites from four organs in five green turtles were identified by established morphological and molecular techniques. Morphological study of adults identified Carettacola sp. in the serosal wall of the gastrointestinal tract, Hapalotrema mehrai in the heart and Learedius learedi in the spleen. Worms from the brain probably belonged to the genus Neospirorchis. DNA sequences from a portion of the 28S ribosomal RNA gene were obtained; but only matches for Hapalotrema mehrai and Learedius learedi were made. The prevalence and severity of this disease warrants further investigation into development of molecular techniques for use as a prognostic tool for turtles entering rehabilitation (Chapter 6). Chelonid corneal fibropapillomatosis, a previously unreported disease manifestation in Australia, was identified in 0.5% of 787 examined green turtles in 2008 (Chapter 7). This novel syndrome was shown to reduce visibility, potentially negatively affecting turtle survivorship and should be monitored for further spread. Findings from this thesis and the published literature were used to derive a mathematical model to determine the effects of identified diseases on Moreton Bay green turtle survivorship. This model demonstrated diseases at current prevalence will not negatively affect survivorship but an adverse environmental disruption or an increase in current disease frequency may threaten these animals (Chapter 8). Information presented in this thesis was used to test the general hypothesis ‘Differences in disease and health between stranded and functional populations of marine turtles will indicate major and currently unmeasured causes of population decline.’ This hypothesis was partially upheld. Differences in disease and health status between stranded and functional populations were demonstrated, but more work is required to comprehensively examine these statuses. Diagnostics and continued environmental assessment should become the focus of future investigations. These findings should be incorporated in future management strategies.
64

Knowledge Management in Software Process Improvement

Bjørnson, Finn Olav January 2007 (has links)
<p>Reports of software a development projects that miss schedule, exceeds budget and deliver products with poor quality are abundant in the literature. Both researchers and the industry are seeking methods to counter these trends and improve software quality.</p><p>Software Process Improvement is a systematic approach to improve the capabilities and performance of software organizations. One basic idea is to assess the organizations’ current practice and improve their software process on the basis of the competencies and experiences of the practitioners working in the organization. A major challenge is to create strategies and mechanisms for managing relevant and updated knowledge about software development and maintenance. Insights from the field of knowledge management are therefore potentially useful in software process improvement efforts to facilitate the creation, modification, and sharing of software processes in any organization.</p><p>In the work presented in this thesis, we have made an overview of empirical studies on the effect of knowledge management in software engineering. We have categorized these studies according to a framework and we report findings on the major concepts that have been investigated empirically, as well as the research methods applied within the field. We have also investigated two main strategies for knowledge management, codification and personalization, through the application of four concrete methods in a software process improvement setting: Mentoring, Rational Unified Process, Process Workshops and Post Mortem Analysis.</p><p>We have classified the work in this thesis within three main themes:</p><p>RT1: Previous research on knowledge management in software engineering.</p><p>RT2: Application of knowledge management to improve the software process through codification of knowledge.</p><p>RT3: Application of knowledge management to improve the software process through personalization of knowledge.</p><p>The main contributions are:</p><p>C1: An overview of the research literature on empirical studies of knowledge management in software engineering.</p><p>C2: A method for tailoring the Rational Unified Process to the development process of a software consulting company.</p><p>C3: Improvements of the Process Workshops method by contextualization.</p><p>C4: Improvement of the root-cause analysis phase of the lightweight Post Mortem Analysis for more effective project retrospectives.</p><p>C5: Proposed methods to increase the learning effect of mentor programs in software engineering.</p>
65

Knowledge Management in Software Process Improvement

Bjørnson, Finn Olav January 2007 (has links)
Reports of software a development projects that miss schedule, exceeds budget and deliver products with poor quality are abundant in the literature. Both researchers and the industry are seeking methods to counter these trends and improve software quality. Software Process Improvement is a systematic approach to improve the capabilities and performance of software organizations. One basic idea is to assess the organizations’ current practice and improve their software process on the basis of the competencies and experiences of the practitioners working in the organization. A major challenge is to create strategies and mechanisms for managing relevant and updated knowledge about software development and maintenance. Insights from the field of knowledge management are therefore potentially useful in software process improvement efforts to facilitate the creation, modification, and sharing of software processes in any organization. In the work presented in this thesis, we have made an overview of empirical studies on the effect of knowledge management in software engineering. We have categorized these studies according to a framework and we report findings on the major concepts that have been investigated empirically, as well as the research methods applied within the field. We have also investigated two main strategies for knowledge management, codification and personalization, through the application of four concrete methods in a software process improvement setting: Mentoring, Rational Unified Process, Process Workshops and Post Mortem Analysis. We have classified the work in this thesis within three main themes: RT1: Previous research on knowledge management in software engineering. RT2: Application of knowledge management to improve the software process through codification of knowledge. RT3: Application of knowledge management to improve the software process through personalization of knowledge. The main contributions are: C1: An overview of the research literature on empirical studies of knowledge management in software engineering. C2: A method for tailoring the Rational Unified Process to the development process of a software consulting company. C3: Improvements of the Process Workshops method by contextualization. C4: Improvement of the root-cause analysis phase of the lightweight Post Mortem Analysis for more effective project retrospectives. C5: Proposed methods to increase the learning effect of mentor programs in software engineering.
66

Cellular Aspects of Lignin Biosynthesis in Xylem Vessels of Zinnia and Arabidopsis

Serk, Henrik January 2015 (has links)
Lignin is the second most abundant biopolymer on earth and is found in the wood (xylem) of vascular land plants. To transport the hydro-mineral sap, xylem forms specialized conduit cells, called tracheary elements (TEs), which are hollow dead cylinders reinforced with lateral secondary cell walls (SCW). These SCWs incorporate lignin to gain mechanical strength, water impermeability and resistance against pathogens. The aim of this thesis is to understand the spatio-temporal deposition of lignin during TE differentiation and the relationship with its neighbouring cells. In vitro TE differentiating cell cultures of Zinnia elegans and Arabidopsis thaliana are ideal tools to study this process: cells differentiate simultaneously into 30-50% TEs while the rest remain parenchymatic (non-TEs). Live-cell imaging of such TEs indicated that lignification occurs after programmed cell death (PCD), in a non-cell autonomous manner, in which the non-TEs provide the lignin monomers. This thesis confirms that lignification occurs and continues long after TE PCD in both in vitro TE cultures and whole plants using biochemical, pharmacological and cytological methods. The cooperative supply of lignin monomers by the non-TEs was demonstrated by using Zinnia and Arabidopsis in vitro TE cultures. Inhibitor experiments revealed further that the non-TEs supply reactive oxygen species (ROS) to TEs and that ROS are required for TE post-mortem lignification. Characterization of the non-TEs showed an enlarged nucleus with increased DNA content, thus indicating that non-TEs are in fact endoreplicated xylem parenchyma cells (XP). The cooperative lignification was confirmed in whole plants by using knock-out mutants in a lignin monomer synthesis gene, which exhibit reduced TE lignification. The XP specific complementation of these mutants led to nearly completely rescuing the TE lignin reduction. Using microscopic techniques, the spatial distribution of lignin was analyzed in TEs from in vitro cultures and whole plants, revealing that lignification is restricted to TE SCWs in both protoxylem and metaxylem. These specific deposition domains were established by phenoloxidases, i.e. laccases localized to SCWs and peroxidases, present in SCWs and the apoplastic space. Laccases were cell-autonomously produced by developing TEs, indicating that the deposition domains are defined before PCD. Altogether, these results highlight that the hydro-mineral sap transport through TEs is enabled by the spatially and temporally controlled lignification of the SCW. Lignification occurs post-mortem by the supply of monomers and ROS from neighbouring XP cells and is restricted to specific deposition domains, defined by the pre-mortem sequestration of phenoloxidases.
67

Relevance of Ethylglucuronide as a marker of alcohol consumption : development of dosage methods and study of factors potentially affecting its production

Al Saabi, Alaa 03 July 2013 (has links) (PDF)
La consommation excessive d'alcool présente des risques élevés pour l'individu et pour la société ; elle est fréquemment associée à une augmentation du risque d'accidents, d'actes de violence, et peut également conduire à court et/ou à long terme à de graves maladies et à des problèmes sociaux. Dès lors, l'utilisation de marqueurs fiables permettant de détecter une consommation excessive d'alcool, ponctuelle ou chronique, s'avère nécessaire pour prévenir des conséquences néfastes de l'abus d'alcool. L'éthylglucuronide (EtG) est un marqueur d'alcoolisation utilisé en toxicologie clinique (alcoologie) et médicolégale. Par rapport aux marqueurs indirects d'alcoolisation (CDT, γ-GT), ce métabolite mineur de l'éthanol est très spécifique et est quantifiable dans diverses matrices biologiques. La production d'EtG est catalysée par des enzymes de la famille des UDP-glucuronosyl-transférases (UGT). Cependant, les UGT impliquées dans la glucuronoconjugaison de l'éthanol, ainsi que les sources potentielles de variabilité interindividuelle de la production d'EtG, sont encore mal connues. Nos travaux ont ainsi consisté à (1) développer et valider une méthode de dosage de l'EtG dans différentes matrices biologiques par chromatographie en phase gazeuse couplée à la spectrométrie de masse en tandem, (2) identifier les UGT humaines impliquées dans la glucuronoconjugaison de l'éthanol et étudier la contribution relative de chaque isoforme active au niveau hépatique, (3) étudier l'impact de substances fréquemment utilisées par les consommateurs d'alcool sur la production d'EtG in vitro, (4) étudier l'impact de polymorphismes génétiques fonctionnels des UGT sur la production hépatique d'EtG, et enfin (5) évaluer l'impact de la consommation de cannabis et d'autres drogues sur la production d'EtG à l'aide de prélèvements post-mortem. Ces travaux ont notamment permis de montrer que (1) l'éthanol est glucuronoconjugué principalement par le foie, puis dans une moindre mesure par les reins et par l'intestin, (2) les UGT1A9 et 2B7 sont les deux enzymes majoritairement impliquées dans la glucuronoconjugaison de l'éthanol, quel que soit l'organe considéré, (3) la morphine, la codéine, la nicotine et la cotinine n'entraînent aucune modification des taux de production d'EtG in vitro ; le lorazépam et l'oxazépam augmentent légèrement cette production (p = 0,2 et 0,065, respectivement) ; le cannabidiol inhibe la glucuronoconjugaison de l'éthanol par un mécanisme non-compétitif (CI50 = 1,17 mg/L; Ki = 3,1 mg/L), alors que le cannabinol augmente cette glucuroconjugaison de manière concentration-dépendante (p <0,05), (4) les SNP c.-900G>A affectant l'UGT2B7 et IVS1+399T>C affectant l'UGT1A9 augmentent légèrement la production d'EtG in vitro. Enfin (5) le rapport des concentrations sanguines EtG/éthanol apparaît significativement plus élevé chez des co-consommateurs de cannabis et/ou d'autres drogues que chez des consommateurs d'alcool seul. L'ensemble de ces résultats démontre l'existence de plusieurs facteurs pouvant potentiellement influencer la production d'EtG et devraient donc être pris en considération lors de l'interprétation de sa concentration in vivo.
68

A study of 1 Peter 3:18- 4:6 : an investigation into the historical background of the doctrine of Christ’s descent into Hades

Du Toit, Marietjie 11 August 2008 (has links)
The aim of this study is to prove that neither 1 Peter 3:19 nor 1 Peter 4:6 refers to the Christian doctrine the ‘Descensus Christi ad Inferos’. The meaning of these two verses has long been debated (cf. Dalton 1989:27-28), and is very often seen as a reference to Christ’s descent into Hades (cf. Feinberg 1986:309). This study will be done by means of a parallel study. The first part of this study will involve the doctrine of the ‘Descensus’; looking at its origin and its development. It will be argued in this section that the roots of this doctrine can be found in Jewish-Christianity and not pagan mythology as has been suggested (cf. Bousset 1907:224ff&Beare 1945:145). The discussion of the doctrine is necessary, since we do need to know more about the doctrine to see whether it is the referent in 1 Peter. The second part of the study will then engage in the meaning of 1 Peter 3:19 and 4:6. This section will be very context driven. We will start with an introduction to 1 Peter, discussing all the preliminary questions (i.e. author, date, audience&form). This will be followed by a structural analysis of 1 Peter. Here it will be argued that the letter should be understood in terms of metaphors, with the ‘Diaspora’ as the controlling metaphor (cf. Martin 1992). The verses under discussion, form part of the third metaphor-cluster namely the ‘Sufferers of the Dispersion’, while the name of our subsection is’ The Righteous Sufferer’. By means of the grammatical analysis, and the influence of the pseudepigraphal book 1 Enoch, it will be shown that these verses do not allow themselves to be interpreted as references to the Descent of Christ into Hades. / Dissertation (MA)--University of Pretoria, 2008. / Ancient Languages / unrestricted
69

Estimating the post-mortem interval using accumulated degree-days in a South African setting

Myburgh, Jolandie 20 June 2011 (has links)
Providing a presumptive identification of badly decomposed or skeletonized remains is the responsibility of a forensic anthropologist. An important component of identification is the estimation of a post-mortem interval (PMI) for the deceased. This information can: provide a window period for death, reduce the number of potential victims, exclude possible assailants and substantiate witness testimony. Due to a large number of open and relatively desolate fields in South Africa, human remains are frequently discovered in an advanced stage of decomposition. The aim of this study was to evaluate the usability of the method of Megyesi and associates (2005) in which Total Body Score (TBS) and Accumulated Degree-Days (ADD) were retrospectively applied to estimate the post-mortem interval (PMI). To achieve this, a longitudinal examination of quantitative variables, TBS and ADD, was conducted over a period of 8 months. This period included both summer and winter seasons. Scatter plots between TBS and PMI, and TBS and ADD were used to illustrate patterns in decomposition. Patterns of decay differed in winter and summer, with winter exhibiting distinct inactivity. Using Loglinear Random-effects Maximum Likelihood Regression, the r2 values for ADD (0.6227) and PMI (0.5503) for combined seasons were less than r2 values for separated seasons (ADD 0.7652; PMI 0.7677). In contrast to other studies, seasonality influenced the ADD model and PMI. Linear regression formulae for ADD and PMI as well as 95% confidence interval charts for TBS for ADD were developed. These equations, along with data from a local weather station, can be used to estimate the PMI with relative accuracy. AFRIKAANS : Verskaffing van 'n vermoedelike identifikasie van erg ontbinde of skeletale oorskot is die verantwoordelikheid van ‘n forensiese antropoloog. ‘n Belangrike deel van identifikasie is die beraming van ‘n post-mortem interval (PMI) vir die oorledene. Hierdie inligting verskaf 'n venster tydperk van dood, verminder die aantal potensiële slagoffers, sluit moontlike aanvallers uit en ondersteun getuienis. As gevolg van 'n groot aantal relatief verlate en oop velde in Suid-Afrika, word menslike oorskot dikwels aangetref in ‘n gevorderde stadium van ontbinding. Die doel van hierdie studie was om die bruikbaarheid van die metode van Megyesi en medewerkers (2005) wat gebruik maak van Totale Liggaams Telling (TLT) en Opgehoopte Graad-Dae (OGD) om die postmortem interval (PMI) te skat, terugwerkend te evalueer. Hiervoor was 'n longitudinale studie van kwantitatiewe veranderlikes, TBS en ADD, oor ‘n tydperk van 8 maande gedoen. Hierdie tydperk sluit beide somer en winter in. Verspreidingsgrafieke tussen TBS en PMI, en TBS en ADD is gebruik om patrone in ontbinding te illustreer. Ontbindingspatrone het verskil tussen winter en somer met duidelike onaktiwiteit in die winter. Logliniêre Tweekansige-effek Maksimum Waarskynlikheid Regressie was gebruik om die r2 waardes van die gekombineerde en geskeide seisoene te bepaal. The r2 waardes vir die OGD (0.6227) en PMI (0.5503) vir gekombineer seisoene was minder as die r2 waardes vir seisoene apart (OGD 0.7652; PMI 0.7677). In teenstelling met ander studies, het seisoenaliteit die OGD model en PMI beinvloed. Lineêre regressie formules vir OGD en PMI sowel as 95% vertrouensinterval kaarte vir TLT vir OGD was saamgestel. Hierdie formules saam met data vanaf ‘n plaaslike weerstasie kan gebruik word om die PMI met relatiewe akkuraatheid te skat. / Dissertation (MSc)--University of Pretoria, 2010. / Anatomy / unrestricted
70

Revue systématique sur les valeurs estimées de paramètres influençant la détection de la tuberculose bovine chez les cervidés d’élevage

Baraheberwa, Nestor 01 1900 (has links)
La tuberculose bovine est une maladie zoonotique se transmettant principalement par inhalation. C’est une maladie qui peut avoir des répercussions économiques (ex : saisie d’un animal infecté à l’abattoir) et sur les échanges commerciaux, car les pays peuvent bannir l’importation des animaux provenant des pays touchés par cette maladie. Au Canada, le contrôle de cette maladie a commencé en 1923 chez les bovins et a ensuite été appliqué chez les cervidés depuis 1989. Ce programme est composé par la surveillance, la réponse aux éclosions, ainsi que le contrôle des mouvements des cervidés. La capacité de détecter cette maladie lors des activités de surveillance est influencée par la performance des méthodes diagnostiques utilisées à chaque étape de la surveillance. À l’abattoir, la surveillance est effectuée par l’inspection visuelle post-mortem et par différentes procédures diagnostiques réalisées sur des prélèvements de tissus anormaux (histopathologie, réaction de polymérisation en chaîne (PCR) ou culture bactérienne). Chez le cervidé vivant, la surveillance est plutôt réalisée par des tests cutanés ou sérologiques. L’objectif principal de ce projet était de fournir, à travers une revue systématique de littérature, les estimés des valeurs des principaux paramètres pouvant influencer la probabilité de détection de la tuberculose bovine dans un contexte de surveillance de cette maladie à l’abattoir chez les cervidés d’élevage et chez les cervidés vivants. Les études qui ont estimé la probabilité de présence des lésions macroscopiques ont trouvé qu’elle variait de 20% à 100% alors que la probabilité de détection des lésions tuberculeuses était supérieure ou égale à 90%. L’estimé de la sensibilité des tests diagnostiques pouvant être utilisés pour la détection de la tuberculose bovine à l’abattoir (histopathologie, PCR et culture) variait de 63.6% à 98.6%. Chez les animaux vivants, les tests sérologiques et sanguins avaient une sensibilité qui variait de faible à élevée (1.4% à 100.0%) alors que les tests cutanés avaient une sensibilité qui variait de 65.0% à 100.0%. Comme le stade de la maladie (temps depuis l’infection) influence la sensibilité de la majorité des tests diagnostiques et que ce facteur n’a généralement pas été rapporté par les études, la performance de ces tests peut difficilement être comparée. La prévalence de la tuberculose estimée lors des études transversales ou de contrôle de la maladie était faible (prévalence au niveau animal au sein d’un troupeau). Une étude effectuée au Canada sur les facteurs de risque de la tuberculose bovine chez les cervidés d’élevage a constaté que l’augmentation de la taille du troupeau était associée à une augmentation du risque de positivité (du troupeau) à la tuberculose bovine. Ces informations sur la performance et les limites des méthodes diagnostiques sont essentielles pour orienter le choix du test diagnostique et pour permettre l’évaluation de la sensibilité des activités de surveillance / Bovine tuberculosis is a zoonotic disease mostly transmitted by inhalation of contaminated material. This disease leads to the economic losses (e.g. condemnation of meat from infected animals at the abattoir) and impede trade since countries can stop importing live cervids from tuberculosis endemic countries. In Canada, the control of bovine tuberculosis started in 1923 in cattle and then was implemented in farmed cervids in 1989. This program is composed of surveillance, response to the outbreaks and movement control of cervids. The capacity of detecting this disease during the surveillance activities depends on the performance of diagnostic methods used at each step of the component of the surveillance system. At the abattoir, the inspection is carried out by visual inspection of organs and carcass and diagnostic tests carried on abnormal tissues by using histopathology, PCR or culture. In live cervids, the detection is carried out through skin or serological testing. The main objective of this project was to provide, through a systematic literature review, the estimates of main parameters that can influence the probability of detecting bovine tuberculosis in the context of surveillance activities in farmed cervids at the abattoir and in live cervids. The probability of presence of macroscopic lesions estimated by studies ranged from 20% to 100% while the estimate of probability of detection of lesions was greater than or equal to 90%. The estimate of sensitivity of diagnostic tests used during bovine tuberculosis surveillance at the abattoir (histopathology, PCR and culture) ranged from 63.6% to 98.6%. In live cervids, studies that investigated the performance of serological tests reported an estimate of sensitivity ranging from low to high (1.4% to 100.0%) while skin tests were reported to have a sensitivity ranging from 65.0% à 100.0%. Given that the stage of the disease affects the performance of most diagnostic test while that variable was not reported by studies, it was difficult to compare the performance of the various tests. Bovine tuberculosis prevalence estimated by studies using a cross-sectional or disease control design reported a low prevalence (prevalence at the animal level within a herd). One study carried out in Canada evaluated the risk factors for bovine tuberculosis infection and found that the increase of herd size was associated with an increase of risk of herd positivity to bovine tuberculosis. This information on the performance and limits of bovine tuberculosis diagnostic tests is critical for orienting the choice of appropriate diagnostic method and for a valid evaluation of the surveillance activities

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