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viii SUMMARY The effect of essential oils and calcified marine algae as natural alternatives to ionophore antibiotics on performance of feedlot cattle by Emile Francois Haasbroek Supervisor: Prof. L.J. Erasmus Department: Animal and Wildlife Sciences Faculty: Natural and Agricultural Sciences Degree: MSc (Agric) Animal Science: Animal Nutrition Ionophore antibiotic supplementation is standard practice in almost all feedlots in the USA, South Africa and many other countries due to its effectiveness to increase feed efficiency and modulate feed intake. Public concern over the emergence of antibiotic resistant bacteria and the consumers’ demand for safe, high quality nutritious food has stimulated the search for natural alternatives to ionophores in ruminant diets. The objectives of this study were: (i) to compare the effect of a specific blend of essential oils (XTract X60 – 7065 (XTract)) and a rumen buffer (Acid Buf) to monensin and its effects on the performance of feedlot cattle under both experimental and commercial conditions (ii) to determine the effect of these feed additives on the health status of feedlot cattle and (iii) to determine whether Acid Buf can replace monensin as feed additive in high energy feedlot diets based on hominy chop. For the experimental growth trial 180 Bonsmara type animals were blocked into two groups and then allocated to 6 pens with 10 animals each per treatment using a randomised complete block design. The basal diets (starter, intermediate finisher and final finisher) were the same for the Control XTract and Acid Buf; the only difference being the Control treatment was supplemented with monensin (21 – 33 mg /kg DM), the XTract treatment supplemented with XTract (1000 – 1200 mg /h /d) and the Acid Buf treatment supplemented with Acid Buf at 0,6% dietary DM. For the commercial trial, animals were blocked according to the same criteria but for each treatment there were 3 pens, standing 130 head of cattle per pen, therefore 390 animals per treatment. The experimental pen trial was designed for evaluation of growth and the commercial pen trial for evaluation of health status and growth under practical feedlot conditions. In the small pen trial there were no differences (P > 0.05) in DMI, FCR or ADG between treatments. In the commercial trial the XTract supplemented cattle had a higher EW (429.3 vs. 417.5 kg) and ADG (1.77 kg /d vs. 1.70 kg /d) (P < 0.05) compared to monensin supplemented cattle and the Acid Buf supplemented cattle tended (P > 0.10) towards a higher EW (425.3 vs. 417.5 kg) and ADG (1.74 vs. 1.70 kg /d) compared to monensin supplemented cattle. The feed conversion ratios were 5.67 and 5.26 for XTract and monensin supplemented cattle and did not differ (P = 0.26). The feed conversion ratios were 5.22 and 5.26 respectively for Acid Buf and monensin supplemented cattle and did not differ (P = 0.86). Treatments affected health parameters in the commercial pens with 78% healthy animals (not pulled) in the monensin supplemented animals compared to 82% for XTract and 66% for the Acid Buf supplemented animals (P < 0.01). Rumen damage occurred in 73% of monensin supplemented animals compared to 51% for the Acid Buf supplemented animals and only 24% of the XTract supplemented animals (P < 0.01). Differences in health parameters did not seem to affect the overall growth performance of the cattle, suggesting a relatively minor effect on performance. Results from this large scale study should provide South African feedlot operators with sufficient information to make informed decisions on natural alternatives when the day comes that ionophores are placed on the banned list of ruminant feed additives. Further research, however, is needed on determining the optimal dose, dietary dependant responses, adaptation of rumen microbial populations and potential additive or synergistic effects when supplemented together with other rumen modifiers. Furthermore, the cost: benefit ratio should be determined under the prevailing conditions in different countries. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

Le rétrécissement aortique calcifié (RAC) est une maladie calcifiante de la valve aortique caractérisée par un remodelage fibro-calcique lentement progressif des feuillets valvulaires, et par un remodelage du ventricule gauche (VG). Il n’existe à ce jour aucun traitement pharmacologique capable de prévenir la maladie, et le seul traitement consiste en un remplacement valvulaire chirurgical ou percutané. Les objectifs de cette thèse étaient d’identifier des déterminants de la progression du RAC et du remodelage VG, d’étudier une nouvelle modalité d’évaluation de la sévérité du RAC, et d’analyser par une approche expérimentale les mécanismes initiateurs de la calcification valvulaire aortique. Les résultats de ce travail peuvent être résumés comme suit : - Le taux plasmatique de galectine-3 n’était pas associé au degré de sévérité du RAC ou au statut fonctionnel des patients. La galectine-3 n’avait pas de valeur pronostique sur la survenue d'événements liés au RAC. Les résultats observés sont en défaveur de l'utilisation de ce biomarqueur au cours de la prise en charge des patients ayant un RAC asymptomatique. - Dans une cohorte prospective de patients ayant un RAC au moins minime, le volume de graisse épicardique était indépendamment associé à un remodelage péjoratif du VG. Ce résultat suggère que la graisse épicardique pourrait être un déterminant du remodelage pathologique du VG via une interaction locale. - L’utilisation de l’imagerie de fusion a entrainé une augmentation du taux de discordance entre les paramètres de sévérité du RAC. Ce résultat était plus marqué chez les patients ayant une valve aortique bicuspide. Au regard de la classification et des seuils définissant actuellement la sévérité du RAC, et du fait de leur valeur pronostique bien démontrée, les résultats de cette étude sont en défaveur de l'utilisation de l’imagerie de fusion pour évaluer la sévérité du RAC. - L’accumulation dans le feuillet valvulaire aortique d’érythrocytes sénescents, suite à la survenue de lésions endothéliales non cicatrisées, constitue une situation délétère favorisant la différenciation des cellules valvulaires interstitielles vers un phénotype ostéoblastique et in fine le dépôt de calcium conduisant au RAC. La physiopathologie d’initiation des calcifications valvulaires et de progression du RAC est complexe et multifactorielle. La découverte de cibles thérapeutiques potentielles et l’optimisation de la prise en charge des patients ayant un RAC nécessite de combiner des études cliniques pour identifier les déterminants de la progression et de la réponse myocardique au cours du RAC, et une approche fondamentale pour caractériser les mécanismes impliqués dans la maladie. / Calcific aortic stenosis (AS) is characterized by a slowly progressive fibrocalcific remodeling of aortic valve leaflets, and by a left ventricular (LV) remodeling. There is currently no effective medical treatment capable of preventing disease progression, and the only treatment is surgical or percutaneous valve replacement. The objectives of this thesis were to identify determinants of AS progression and LV remodeling, to study a new modality of evaluation of AS severity, and to analyze through an experimental approach the initiating mechanisms of valve calcification. The results of this work can be summarized as follows: - The plasmatic level of galectin-3 was not associated with the degree of AS severity or the functional status of patients. Galectin-3 had no prognostic value for the occurrence of AS-related events. The results observed are not in favor of the use of this biomarker for the management of patients with asymptomatic AS. - In a prospective cohort of patients with at least mild AS, epicardial fat volume was independently associated with an adverse remodeling of the LV. This result suggests that epicardial fat may be a determinant of pathological LV remodeling through a local interaction. - The use of fusion imaging increased the rate of discordant AS severity parameters. This result was more pronounced in patients with a bicuspid aortic valve. Considering current classification and thresholds defining AS severity, and their well-proven prognostic value, the results of this study do not favor the use of fusion imaging to assess AS severity. - The accumulation of senescent erythrocytes in aortic valve leaflets, consecutive to unhealed endothelial injury, is a noxious condition that promotes the differentiation of valvular interstitial cells towards an osteoblastic phenotype and favor calcium deposition leading to AS. The pathophysiology of initiation of valvular calcification and AS progression is complex and multifactorial. The discovery of potential therapeutic targets and the optimization of the management of patients with AS require the combination of clinical studies to identify the determinants of AS progression and myocardial response, and a fundamental approach to characterize mechanisms involved in the disease.

Atherosclerosis causes hundreds of thousands of deaths in the US alone every year. Fibrous cap rupture is one of the leading causes of these fatalities. Thin cap atheromas are commonly regarded as vulnerable plaque, however the effect of calcium upon a thin fibrous cap with lipid pool is poorly understood. Some studies have shown that calcium adds to stability of the lesion, while others have proven otherwise. An article by Li et al. 2007 suggests location is the key factor. By varying the percentage of calcium and lipid within a defined region, the stress on the cap was estimated using an idealized finite element arterial model. Also the thickness of the fibrous cap was varied to determine whether the stress was solely a function of lipid percentage or a combination. Plaque, arterial wall, lipid, and calcium were modeled using linear elastic, isotropic, and incompressible material properties. The first test varied the thin cap thickness from 65 to 500 microns and tested the calcified lipid model at varying lipid/calcium percentages. The lipid/Calcium pool increased/decreased 10% each test. As the cap thickness becomes thinner than 100 microns, the stress level increases rapidly. The second test compared a model with lipid pool and calcium behind the lipid with a thin cap of 65 microns to a model with lipid pool of the same size and thin cap of 65 microns but only fibrous tissue surrounding (no calcium). The lipid pool increased from 10 to 90% lipid. The result of this test found that at higher lipid percentages, the calcium increased the stress on the cap. By understanding the material properties of plaque and the structure of the lesion, future developments may be able to evaluate rupture risk. This idealized study illustrates the ability of computation models to provide insight into clinical situations.

Introdução: O declínio cognitivo relacionado à neurocisticercose (NC) ainda permanece mal caracterizado e pouco diagnosticado. Recentemente, nosso grupo mostrou que uma significativa parcela de pacientes com NC na fase cística ativa apresenta-se com declínio cognitivo e comprometimento funcional (Ciampi de Andrade et al., 2010). Não existem estudos controlados que avaliem essas alterações em pacientes com NC na fase calcificada na literatura até presente momento. Objetivos: Avaliar o desempenho cognitivo do maior subgrupo de NC, constituído de pacientes com NC na fase estritamente calcificada (C-NC). Verificar a presença de demência e comprometimento cognitivo sem demência (CCSD) nesses pacientes e tentar correlacionar os resultados obtidos a achados de neuroimagem. Investigar se existe presença de um espectro de anormalidade cognitiva na NC conforme a fase da doença. Metódos e Casuística: Quarenta pacientes (média de idade = 37,6+ 11,3 anos e escolaridade média= 7,0+ 3,5 anos), com critérios diagnósticos absolutos de C-NC foram submetidos à avaliação cognitiva e funcional, sendo comparados a 40 pacientes controles saudáveis (CS) e 40 pacientes com NC ativa (A-NC), emparelhados por idade e nível educacional. Todos os pacientes do grupo C-NC foram submetidos a estudo de RM de encéfalo, a fim de excluir outras causas de epilepsia e sinais de atividade inflamatória. Resultados: Os doentes C-NC apresentaram uma média de 9,40 ± 3,13 testes alterados dos 30 da bateria de avaliação cognitiva quando comparados aos CS. Nenhum paciente C-NC mostrou critérios para demência e 10 (25%) tiveram critérios para CCSD. O grupo ANC tinha 5 pacientes (12,5%) com demência e 11 (27,5%) com CCSD. Mais de 50% dos doentes C-NC apresentaram desempenho inferior em memória verbal, atenção e função executiva em comparação aos CS. Não se encontrou correlação entre as alterações nos testes cognitivos nos pacientes C-NC e A-NC e os achados de neuroimagem e a frequência de crises epilépticas. Dos 4 pacientes reavaliados com demência do grupo A-NC após 2 anos, 3 deles ainda mantinham critérios de demência e na reavaliação por neuroimagem ainda apresentavam cistos. O único que não mais preenchia critérios para demência ou CCSD, exibia apenas calcificações na neuroimagem controle. Conclusões: Os resultados do presente estudo controlado indicaram que a NC independente de sua fase leva a um espectro de alterações cognitivas que varia de comprometimento em um simples domínio, CCSD até, ocasionalmente, demência. Estes achados parecem ser mais intensos durante a fase ativa cística da doença e menos proeminentes no estágio calcificado / Introduction: Cognitive decline related to neurocysticercosis (NC) remains poorly characterized and underdiagnosed. We have previously shown that a significant proportion of active NC patients (A-NC) present cognitive and functional impairment. Until now, there is no control study that have evaluated cognitive abnormalities in patients in the calcified phase of NC. Objective: To evaluate the cognitive performance of the largest subgroup of NC, the strict calcified patients (C-NC). Check the presence of dementia and cognitive impairment no-dementia (CIND) and correlate the results with neuroimaging findings. To investigate whether there is a spectrum of cognitive abnormalities in the disease according to disease phase. Methods and participants: Forty treatment-naive patients with C-NC aged 37.6 ± 11.3 years and fulfilling absolute criteria for definitive C-NC were submitted to a comprehensive cognitive and functional evaluation and were compared with 40 active NC patients (A-NC) and 40 healthy controls (HC) matched for age and education. All patients of C-NC group underwent brain MRI study in order to exclude other causes of epilepsy and signs of inflammatory activity. Results: Patients with C-NC presented 9.4 ± 3.1 altered test scores out of the 30 from the cognitive battery when compared to HC. No C-NC patient had dementia and 10 patients (25%) presented CIND. The A-NCYST group had five patients (12.5%) with dementia and 11 patients (27.5%) with CIND. More than 50% of C-NC patients had low performance in verbal memory, attention and executive functions in comparison to CS. No significant correlation was found between cognitive performance and the number of lesions and seizure frequency. On follow-up, three out of five previously demented A-NCYST patients still presented cystic lesions with scolex on MRI and were still demented. One patient died and the remaining patient no longer fulfilled criteria for neither dementia nor CIND, presenting exclusively calcified lesions on neuroimaging. Conclusion: The results of our controlled study shows that NC, independently of its phase, leads to a spectrum of cognitive abnormalities, ranging from impairment in a single domain, to CIND and, occasionally, to dementia. These findings are more conspicuous during active vesicular phase and less prominent in calcified stages

Introdução: O declínio cognitivo relacionado à neurocisticercose (NC) ainda permanece mal caracterizado e pouco diagnosticado. Recentemente, nosso grupo mostrou que uma significativa parcela de pacientes com NC na fase cística ativa apresenta-se com declínio cognitivo e comprometimento funcional (Ciampi de Andrade et al., 2010). Não existem estudos controlados que avaliem essas alterações em pacientes com NC na fase calcificada na literatura até presente momento. Objetivos: Avaliar o desempenho cognitivo do maior subgrupo de NC, constituído de pacientes com NC na fase estritamente calcificada (C-NC). Verificar a presença de demência e comprometimento cognitivo sem demência (CCSD) nesses pacientes e tentar correlacionar os resultados obtidos a achados de neuroimagem. Investigar se existe presença de um espectro de anormalidade cognitiva na NC conforme a fase da doença. Metódos e Casuística: Quarenta pacientes (média de idade = 37,6+ 11,3 anos e escolaridade média= 7,0+ 3,5 anos), com critérios diagnósticos absolutos de C-NC foram submetidos à avaliação cognitiva e funcional, sendo comparados a 40 pacientes controles saudáveis (CS) e 40 pacientes com NC ativa (A-NC), emparelhados por idade e nível educacional. Todos os pacientes do grupo C-NC foram submetidos a estudo de RM de encéfalo, a fim de excluir outras causas de epilepsia e sinais de atividade inflamatória. Resultados: Os doentes C-NC apresentaram uma média de 9,40 ± 3,13 testes alterados dos 30 da bateria de avaliação cognitiva quando comparados aos CS. Nenhum paciente C-NC mostrou critérios para demência e 10 (25%) tiveram critérios para CCSD. O grupo ANC tinha 5 pacientes (12,5%) com demência e 11 (27,5%) com CCSD. Mais de 50% dos doentes C-NC apresentaram desempenho inferior em memória verbal, atenção e função executiva em comparação aos CS. Não se encontrou correlação entre as alterações nos testes cognitivos nos pacientes C-NC e A-NC e os achados de neuroimagem e a frequência de crises epilépticas. Dos 4 pacientes reavaliados com demência do grupo A-NC após 2 anos, 3 deles ainda mantinham critérios de demência e na reavaliação por neuroimagem ainda apresentavam cistos. O único que não mais preenchia critérios para demência ou CCSD, exibia apenas calcificações na neuroimagem controle. Conclusões: Os resultados do presente estudo controlado indicaram que a NC independente de sua fase leva a um espectro de alterações cognitivas que varia de comprometimento em um simples domínio, CCSD até, ocasionalmente, demência. Estes achados parecem ser mais intensos durante a fase ativa cística da doença e menos proeminentes no estágio calcificado / Introduction: Cognitive decline related to neurocysticercosis (NC) remains poorly characterized and underdiagnosed. We have previously shown that a significant proportion of active NC patients (A-NC) present cognitive and functional impairment. Until now, there is no control study that have evaluated cognitive abnormalities in patients in the calcified phase of NC. Objective: To evaluate the cognitive performance of the largest subgroup of NC, the strict calcified patients (C-NC). Check the presence of dementia and cognitive impairment no-dementia (CIND) and correlate the results with neuroimaging findings. To investigate whether there is a spectrum of cognitive abnormalities in the disease according to disease phase. Methods and participants: Forty treatment-naive patients with C-NC aged 37.6 ± 11.3 years and fulfilling absolute criteria for definitive C-NC were submitted to a comprehensive cognitive and functional evaluation and were compared with 40 active NC patients (A-NC) and 40 healthy controls (HC) matched for age and education. All patients of C-NC group underwent brain MRI study in order to exclude other causes of epilepsy and signs of inflammatory activity. Results: Patients with C-NC presented 9.4 ± 3.1 altered test scores out of the 30 from the cognitive battery when compared to HC. No C-NC patient had dementia and 10 patients (25%) presented CIND. The A-NCYST group had five patients (12.5%) with dementia and 11 patients (27.5%) with CIND. More than 50% of C-NC patients had low performance in verbal memory, attention and executive functions in comparison to CS. No significant correlation was found between cognitive performance and the number of lesions and seizure frequency. On follow-up, three out of five previously demented A-NCYST patients still presented cystic lesions with scolex on MRI and were still demented. One patient died and the remaining patient no longer fulfilled criteria for neither dementia nor CIND, presenting exclusively calcified lesions on neuroimaging. Conclusion: The results of our controlled study shows that NC, independently of its phase, leads to a spectrum of cognitive abnormalities, ranging from impairment in a single domain, to CIND and, occasionally, to dementia. These findings are more conspicuous during active vesicular phase and less prominent in calcified stages

Eagle syndrome is a rare clinical condition that is characterized by either an elongated styloid process or a calcified stylohyoid ligament. This report describes the case of a 35-year-old woman who presented with Eagle syndrome following the treatment of recurrent laryngeal carcinoma with ionizing radiation.

Abstract Osteoarthritis is a common joint disease in the adult population characterized by degeneration and limited repair capability of articular cartilage. Cartilage degeneration is also associated with remodeling and sclerosis of the subchondral bone. The relative contributions of these processes are not fully understood partly because of a lack of proper biomarkers for the diagnosis and follow-up of the disease progress. Current diagnostic methods are too insensitive or subjective for reliable and early diagnosis of osteoarthritis. Novel magnetic resonance imaging (MRI) techniques can be used for indirect assessment of cartilage constituents. In addition, the imaging of the subchondral bone and osteochondral junction has become feasible, which has been very difficult with conventional MRI methods due to the very fast signal (T2) decay in those tissues. Quantitative MRI of cartilage involves measurement of relaxation time parameters (T1, T2, T1ρ, T2ρ, TRAFF, T1sat) and investigation of how the parameters reflect the properties of the cartilage. SWIFT (Sweep imaging with Fourier transform) is an MRI technique capable of imaging short T2 structures, enabling assessment of the osteochondral junction as well as the subchondral bone. The aim of this work was to investigate osteoarthritic changes occurring in articular cartilage and subchondral bone in experimental animal models of osteoarthritis and degenerated human specimens with quantitative MRI measurements and SWIFT imaging at 9.4 T. Moreover, the feasibility of the different quantitative MRI techniques in the assessment of osteoarthritic changes was studied. For reference, biomechanical, quantitative and qualitative histology, biochemical and micro-computed tomography measurements were conducted. Novel adiabatic T1ρ and T2ρ relaxation time parameters were more sensitive than conventional methods (T1, T2) or continuous wave T1ρ to both early degenerative changes in a rabbit model of cartilage degeneration and to spontaneous degeneration of human cartilage. SWIFT enabled assessment of the structural properties of the subchondral bone. Moreover, signal changes related to the degree of osteoarthritis were detected at the cartilage–bone interface with SWIFT. These methods may provide new tools for improving the diagnosis of early osteoarthritis. Further studies are needed to investigate the clinical feasibility of these MRI techniques. / Tiivistelmä Nivelrikko on yleinen nivelsairaus, johon ei tällä hetkellä ole parannuskeinoa. Nivelrikossa nivelrusto rappeutuu asteittain aiheuttaen lopulta kudoksen tuhoutumisen; samanaikaisesti myös rustonalaisessa luussa sekä rusto–luurajapinnassa tapahtuu muutoksia. Nivelrustokudoksen uusiutumiskyky on erittäin heikko, joten vauriot olisi hyvä havaita varhaisessa vaiheessa. Nivelrikon syntymekanismeja ei kuitenkaan vielä täysin ymmärretä, koska nykyiset seurantamenetelmät eivät ole riittävän tarkkoja taudin etenemisen tarkkailemiseksi. Magneettikuvausteknologian kehitys mahdollistaa kuitenkin nivelruston koostumuksen tarkastelun nivelen ulkopuolelta. Kvantitatiivisen magneettikuvauksen avulla (T1, T2, T1ρ, T2ρ, TRAFF, T1sat relaksaatioaikaparametrit) voidaan mitata epäsuorasti nivelruston koostumusta ja rakennetta. SWIFT (Sweep Imaging with Fourier Transform) on uusi lyhyen kaikuajan magneettikuvausmenetelmä, joka mahdollistaa myös erittäin lyhyen T2-relaksaatioajan omaavien kudosten, kuten rusto–luurajapinnan sekä rustonalaisen luun kuvaamisen. Työssä tutkittiin nivelrikossa syntyviä muutoksia nivelrustossa, rusto–luurajapinnassa ja rustonalaisessa luussa erilaisissa eläinmalleissa sekä ihmiskudoksessa. Lisäksi työssä tarkasteltiin eri magneettikuvaustekniikoiden herkkyyttä havaita muutokset näissä kudoksissa. Nivelruston ja rustonalaisen luun ominaisuuksien määrittelemiseen käytettiin verrokkimenetelminä biomekaanisia, histologisia sekä biokemiallisia mittauksia ja tietokonetomografiakuvauksia. Kvantitatiivisista magneettikuvausparametreista adiabaattinen T1ρ sekä adiabaattinen T2ρ osoittautuivat herkimmiksi havaitsemaan muutoksia varhaisen nivelrikon eläinmallissa sekä ihmiskudosnäytteissä. SWIFT-magneettikuvaustekniikka puolestaan mahdollisti sekä rustonalaisen luukudoksen tilan arvioinnin että nivelrikossa tapahtuvien muutosten havainnoinnin rusto–luurajapinnassa. Nämä menetelmät voivat mahdollistaa nivelrikon diagnosoinnin taudin varhaisessa vaiheessa, mutta lisätutkimuksia vaaditaan menetelmien soveltuvuudesta kliiniseen käyttöön.

Le travail présenté dans ce manuscrit concerne la fabrication de biomatériaux poreux à base d’acide polylactique pour les tissus conjonctifs et calcifiés en utilisant des procédés de chimie verte. Le but de cette thèse est de corréler l’influence de certains paramètres de procédés à la structure morphologique et les propriétés des mousses générées. Nous avons étudié, d’un côté, les effets de mélange d’acide hyaluronique et d’acides polylactiques afin d’améliorer les propriétés d’adhésion de ces biomatériaux. Nos résultats montrent bien une augmentation de l’énergie d’adhésion mais aussi une diminution de la taille équivalente des pores et de la porosité des biomatériaux poreux après moussage par les fluides supercritiques. D’un autre côté, nous avons étudié les effets de mélanges des triphosphates de calcium et d’acides polylactiques en tant que substitut osseux. L’influence d’un ajout de cires en tant qu’agent porogène a été discutée et les méthodes de préparation des pastilles (voie sèche ou humide) ont été analysées. Dans cette optique la fabrication semi-industrielle de biomatériaux poreux a été testée en fixant les paramètres du procédé de moussage par le CO2 supercritique (pression, température et temps de saturation, vitesse de dépressurisation) et nous avons contrôlé les mousses de formulations optimisées en termes de porosité et de distribution des pores. En conclusion, ce travail rend possible d’adapter les paramètres des procédés de CO2 supercritique et de co-broyage aux propriétés des biomatériaux poreux. En perspective, cette ouvre la voie à de nouvelles recherches à la fois dans les domaines des modèles 3D tumoraux et d’ingénierie tissulaire. / The work presented in this manuscript concerns the production of scaffolds based polylactides for connective tissues and bone regeneration by adapting green technology. The aim of this thesis was to correlate the influence of different process parameters on the morphological structures and properties of the scaffold generated. On one hand, we studied effect of the blending of hyaluronic acid and polylactides to enhance the surface adhesion properties of scaffolds. Our results relate to an increase in surface properties but a decrease of equivalent pore size and porosity after foaming scaffolds by supercritical process. Calcium Tri-Phosphate On other hand, we studied the effect of the blending of calcium tri-phosphates and polylactides as bone substitute. Influence of adding wax as porogen agent has been discussed and a comparison between wet and dry methods to generate scaffolds has been analyzed. For this purpose, semi-industrial fabrication of porous biomaterials has been tested by blocking supercritical CO2 parameters (saturation pressure, temperature and time, depressurization rate) and you have control the optimized formulation composite scaffold, in term of porosity and distribution of pores. In conclusion, this work made it possible to adapt the process parameters of supercritical CO2 and co-grinding at the properties of scaffolds. In perspective, this research opens new development ways in scaffolds, in both domains of 3D tumoral model and tissue engineering.

In einer initialen Studie verglichen wir das XQi Revolution, welches auf indirektem CsI (Cäsium Iodit) /a: Si (amorphes Silizium) basiert mit einem direkten Digitalröntgengerät a: SE (amorphes Selen) an einem CDRAD-Phantom bei vier unterschiedlichen Eintrittsdosen und an einem TRG-Phantom bei zwei unterschiedlichen Eintrittsdosen. Mittels des berechneten Bildqualitätsfaktors des CDRAD-Phantoms konnten wir zeigen, daß das indirekte im Vergleich zum direkten System bei niedrigeren Dosen eine bessere Detailerkennungsrate aufweist. Ein positiver Trend läßt sich auch beim TRG-Phantom darstellen. In einer weiteren Studie untersuchten wir anhand von Patientenbildern die Bildqualität des Dual Energy Systems bei zwei unterschiedlichen Dosisniveaus, der Standarddosis sowie einer doppelten Dosis, was einem Speed-Äquivalent von 400/1000 bzw. 200/500 entspricht. Bei hoher Dosis konnten wir eine signifikante Reduktion des Rauschens im Knochen- und Weichteilbild feststellen, gleichzeitig nahmen die Störungen durch Bewegungsartefakte signifikant zu. Im Anschluß verglichen wir die Erkennbarkeit verkalkter Lungenpathologien im Standard P/A Bild mit zusätzlichem Einsatz von Dual Energy. Als Goldstandard erfolgte der sichere Nachweis der Pathologien im CT. Bei zusätzlichem Einsatz von Dual Energy konnten wir eine signifikante Steigerung der Sensitivität erkennen. Dieses Ergebnis wurde durch den Qualitätsfaktor, der die Bildeigenschaften kumulativ beschreibt, bestätigt. Weiterhin untersuchten wir analog die Erkennbarkeit von nichtverkalkten Lungenrundherden. Auch bei diesen Pathologien ließ sich ein positiver Trend der Sensitivität und Spezifität bei zusätzlichem Einsatz von Dual Energy erkennen. Zusätzlich stieg die durchschnittliche Entscheidungssicherheit der Gutachter signifikant an. Damit bietet die Dual Energy Subtraktionstechnik eine wertvolle Ergänzung in der Diagnostik verkalkter und nichtverkalkter Lungenpathologien eine wertvolle Ergänzung zum Standardröntgen. / First study assess and quantify the image quality at two dose levels for an amorphous Silicon (a:Si) Cesium Iodide (CsI) flat panel system compared with a direct amorphous Selenium (a:Se) digital radiography system. Image quality of a:Si flat panel digital radiography proved to be superior to a:Se drum digital radiography using low-dose settings. Second study assess the image quality of subtracted soft tissue and bone images of a CsIdetector-based dual-energy system for chest radiography at varying dose levels. Radiation dose did not significantly influence the perception of dual-energy image quality. Next study assess the value of dual-energy chest radiography obtained using a cesium iodide flat-panel detector in addition to standard posteroanterior chest radiography for the detection of calcified chest abnormalities. When dual-energy images were added, sensitivity increased significantly. Brunner and Langer’s test revealed a highly significant difference between posteroanterior chest radiography and dual-energy imaging in the detection of calcified chest abnormalities. Dual-energy images added to standard posteroanterior chest radiographs significantly improve the detection of calcified chest lesions. Last study compare the sensitivity and specificity of digital chest radiography alone with digital chest radiography combined with dual-energy chest radiography in the detection of small non-calcified pulmonary nodules. Standard and dual-energy radiographs were obtained with a flat-panel digital chest system. The increase of nodule detection overall as well as for different size categories was significant. The increase of the confidence level rating was also significant. Dual energy added to standard posteroanterior chest radiography significantly improves the sensitivity, specificity, and confidence in detection of small non-calcified pulmonary nodules. Dual-energy subtraction has the potential to become a future routine application in chest radiography.