Zinc is widely used as an alternative to antibiotic in piglets. Recent studies demonstrated the antibacterial effect of zinc nanoparticles. It is believed that zinc nanoparticles will exhibit better antibiotic effects than previously used medication zinc. There is a need to define ZnNPs effect on the organism. This thesis compares the influence of administration of zinc oxide nanoparticles and zinc standard forms at the dose of 2000 mg/Zn/kg diet in rat organism. The antioxidant status of rats and toxicity of zinc and zinc nanoparticles were monitored. The level of accumulated zinc for blood was on average 12 mg / kg ± 6 mg / kg, for liver 74 mg / kg ± 50 mg / kg, for kidneys 37 mg / kg ± 30 mg / kg for both nanoparticles and normal zinc . ZnNPs and zinc oxide did not extremely influence antioxidant status of samples of blood, liver and kidney. A significant effect was observed with GSH levels. Histological study of liver and duodenum showed slight tissue damage after administration of both zinc and nanoparticles. Zinc nanoparticles demonstrated beneficial effects as well as standard form.

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2022 / La greffe de peau autologue chez les grands brûlés est une technique répandue, mais souvent limitée lorsque le patient présente une petite surface disponible pour le prélèvement des greffons. Les substituts de peaux bilamellaires autoassemblés (PRB) permettent de pallier cette limitation, mais leur production est longue. Le but de cette étude est donc d'optimiser la méthode pour réduire le délai nécessaire avant la première greffe. Pour cela, nous souhaitons développer une technique de décellularisation et d'entreposage de dermes allogéniques produits par autoassemblage. Notre hypothèse est que les PRB produites avec les dermes reconstruits décellularisés (DRD) sont comparables aux PRB préparées avec le protocole du LOEX (Germain et al., 2018) présentement en essai clinique. Nos objectifs sont de trouver les conditions permettant d'éliminer les résidus allogéniques des dermes décellularisés et de les recellulariser de manière à soutenir la différenciation épidermique et la formation de la jonction dermoépidermique. Nous avons déterminé que l'utilisation de deux cycles de choc osmotique avec 0,4 mg/mL de DNAse permet de réduire la quantité résiduelle d'ADN allogénique en dessous de 50ng/mg de tissu sec. L'entreposage d'un mois permet de complémenter cette décellularisation en diminuant la dose de DNAse nécessaire à 0,2mg/mL. En testant différentes populations pour la formation matricielle et densités de fibroblastes pour la recellularisation de DRD, nous avons déterminé que la recellularisation d'une matrice riche en collagène avec une faible densité de fibroblastes (10 000 f/cm$^2$) permet d'obtenir des PRB similaires histologiquement aux PRB standards. Cette recellularisation permet également de regagner les glycosaminoglycanes et l'épaisseur perdues lors de la décellularisation. En conclusion, la méthode de décellularisation utilisée est efficace pour l'atteinte des seuils établis par la littérature et complémentée par l'entreposage des DRD. La recellularisation de ces matrices permet l'obtention de PRB de manière accélérée par rapport à la méthode classique. Le tout est adapté pour une translation clinique. / Autologous skin grafting in burn patients is a widespread technique, but often limited when patients have a small area available for graft harvesting. Self-assembled skin substitutes (SASS) can overcome this limitation, but their production is time consuming. The aim of this study is therefore to optimize the method in order to reduce the time required before the first graft. To this end, we aim to develop a technique for decellularization and storage of allogeneic dermis produced by the self-assembly approach. Our hypothesis is that SASS produced with decellularized reconstructed dermis (DRD) are comparable to autologous SASS prepared with the LOEX protocol(Germain et al., 2018) currently in clinical trial. Our objectives are to find conditions to remove allogeneic residues from decellularized dermis and recellularize it in a way that supports epidermal differentiation and dermal-epidermal junction formation. We determined that the use of two cycles of osmotic shock with 0.4 mg/mL DNAse reduces the residual amount of allogeneic DNA below 50 ng/mg of dry tissue. Storage for one month helps this decellularization by reducing the dose of DNAse required to 0.2 mg/mL. By testing different fibroblast populations and densities for recellularization, we determined that recellularization of a collagen-rich matrix with a low fibroblast density (10 000 f/cm2) yields SASS histologically similar to standard SASS. This recellularization also allows the retrieval of the glycosaminoglycans and thickness lost during decellularization. In conclusion, the decellularization method used is effective in meeting the thresholds established in the literature and is complemented by DRD storage. The recellularization of these matrices allows the obtention of SASS in an accelerated manner compared to the conventional method. This is suitable for clinical translation.

Les images acquises avec un tomodensitomètre à double énergie (DECT) fournissent la détermination du numéro atomique effectif et de la densité électronique. L'objectif de ce mémoire est de développer un modèle d'identifiation de tissu applicable en curiethérapie, le modèle de tissu réduit à trois éléments, basé sur ces quantités et de le comparer avec une méthode existante dans la littérature, le calcul de la distance de Mahalanobis. Les deux modèles sont appliqués à des images DECT du fantôme de calibration Gammex RMI 467 et pour un sous-ensemble de tissus. Les distributions de dose sont calculées avec des simulations numériques Monte Carlo avec une source point ayant le spectre d'énergie de l'iode 125. Le modèle de tissu réduit à trois éléments reproduit les distributions de dose de référence et peut être utilisé comme étant une méthode d'identifiation de tissu valide pour effectuer un calcul de dose à partir d'images DECT. / Clinical Dual-Energy Computed Tomography (DECT) images provide the determination of the effective atomic number and the electronic density. The purpose of this study is to develop a new assessment model of tissues, named the reduced three elements tissue model, for dose calculations from DECT images in brachytherapy and compare it to a known identification method, assignment through the Mahalanobis distance. Both models are applied to DECT scans of the Gammex RMI 467 phantom and for a subset of 10 human tissues. Dose distributions are calculated from Monte Carlo simulations with a point source having the energy spectrum of 125I. The reduced three elements tissue model provides dose equivalence to reference tissues and is equivalent to the calculation of the Mahalanobis distance. The model constructed can be used as a scheme to assess tissues from DECT images for dose calculation.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Zugl.: Giessen, Universiẗat, Diss., 2009.

Zugl.: Leipzig, Univ., Diss., 2009

Zugl.: Giessen, Univ., Diss., 2009

University, Diss., 2004--Bonn.

The main goal of this paper was to evaluate the influence of live weight on both the quantity and the quality of back fat as well as on histology of adipose tissue in pigs. Fourty pigs of PIC genotype and equaly distributed sex were included in this study. The population was then divided into four sub-groups according to their live weight. (Groups: first - under 104.9 kg, second - between 105 kg and 109.9 kg, third - between 110 kg and 114.9 kg, fourth - above 115 kg) The following indicators of fattening performance were monitored during the study: average daily feed consumption, average weekly feed consumption, average daily weight gain and feed conversion rate. Statistically significant influence was observed only for average daily weight gain which was found to be positively dependent on live weight increases. The smallest average daily weight gain (990.14 g) was observed in group one which at the same time displayed highest feed conversion rate (2.61 kg.kg-1). Subjects in group four, on the other hand, showed the largest average daily weight gain (1159.11 kg) and the lowest feed conversion rate (2.49 kg.kg-1). Furthermore, development of back fat was periodically monitored via ultrasound examinations at three chosen points of the pigs' anatomy, beginning at four weeks of age and continuing until ten weeks of age. The measurements confirmed that the increases in depth of back fat correlate closely with gains in live weight. No correlation was proven between other physical characteristics of back fat and changes in live weight. However, measurements showed statistically non-significant increase of coloration of back fat which correlated with weight gains for subjects under 114.9 kg of live weight. As far as tenderness of back fat is concerned, lowest values were found in both upper (74.31 N) and lower (59.61 N) fat in subjects in group two. No significant influence of live weight on the histology of adipose tissue was found. Nevertheless, measurements showed apparent structural difference between the cut in the higher and lower part of back fat. In upper part of the cut was the highest density of adipose cells (60.27 cells per 1 mm2 at the average cell size of 3430.23) found in group number two. However, in the lower part of the cut was the highest density of adipose cells (63.8 cells per 1 mm2 at the average cell size of 3877.72) found in group number one. None of the other monitored variables proved to be statistically significant.

No description available.