Thesis (M.Eng.). / Written for the Dept. of Chemical Engineering. Title from title page of PDF (viewed 2008/05/13). Includes bibliographical references.

No description available.

Thesis (Ph. D.)--University of Michigan, 1930. / "Reprinted from the American journal of anatomy, vol. 48, no. 2, July, 1931." "Literature cited": p. 389-390.

Objectifs : Il n’existe pas de valve de remplacement idéale à l’heure actuelle. L’utilisation du péricarde autologue pour confectionner une valve de remplacement dans le même temps opératoire est une alternative intéressante. Le but de cette étude est de mettre au point une nouvelle méthode de préparation des tissus utilisant un gel polysaccahridique et de standardiser les techniques de préparation, de fabrication et d’implantation de la néo-valve péricardique. Méthodes : Au total 18 moutons ont été opérés pour un remplacement valvulaire aortique par autogreffe péricardique traitée par gel de polymère ou glutaraldéhyde dans les conditions physiologiques d’une chirurgie à coeur ouvert sous circulation extra-corporelle. La néo-valve a été implantée au niveau de l’anneau valvulaire natif par 3 hémi-surjets au Prolène 5/0 avec l’utilisation d’instruments dédiés conçus grâce à l’étude ex-vivo. Les moutons survivants sont sacrifiés à un an pour une évaluation histologique de l’implant tissulaire péricardique.Résultats : Le temps moyen de confection de l’autogreffe péricardique est de 15.68 +/- 4.84 mn, pour un temps de CEC moyen de 136.17 +/- 27.46 mn. Le temps de clampage aortique moyen est de 85.61 +/- 12.21mn. Le gradient moyen trans-valvulaire est de 4,1 mmHg. Les valves prétraitées au glutaraldéhyde sont plus massivement calcifiées que celles traitées par le gel de polymère.Conclusion : L’utilisation du péricarde autologue dans la reconstruction valvulaire aortique est une alternative intéressante surtout chez l’enfant et sur les petits anneaux. L’utilisation d’instruments dédiés permet de rendre la fabrication et l’implantation de la néo-valve plus simple et plus reproductible avec des temps de CEC et de clampage raisonnables. Le gel de polymère donne de meilleurs résultats histologiques que le glutaraldéhyde. / Objective: Ideal prosthetic heart valve is not available. The use of the patient own pericardium for construction heart valve prosthesis is an interesting alternative and has several potential advantages. The aim of our study is to set up a new method for pericardium preparation with polysaccharide hydrogel and standardize the valve treatment processing and implantation.Méthods: Eighteen sheep underwent aortic valve replacement with autologous pericardium valve traited with polymeric gel or glutaraldéhyde using cardio-pulmonary bypass. The pericardial prosthesis was implanted with a proximal running 5/0 Prolène sutures placed along the aortic annulus and utilization of specially designed instruments. Survival sheep were euthanized after 12 months for histologic evaluation of the pericardial valvular implant.Results: Cardiopulmonary bypass and cross-clamp mean time was 136.17 +/- 27.46 mn and 85.61 +/- 12.21mn respectively. The prosthesis mean time construction was 15.68 +/- 4.84 mn. The mean transvalvular gradient after implantation was 4,1mmHg. The autologous pericardial valves treated with glutaraldehyde tended to show more extensive calcification than pericardial valves treated with polymeric gel.Conclusion: Truly stenless aortic valve replacement using autologous pericardium is feasible with cross clamping time acceptable and technically reliable with the use of specially designed instruments. The use of polymeric gel for treatment of autologous pericardial valve is less aggressive than glutaraldéhyde.

Thesis--Ph. D., University of Hong Kong.

No description available.

Perikardpunktionen werden neben diagnostischen Anwendungen vor allem in Notfallsituationen, wie bei einer Perikardtamponade, eingesetzt und können dann lebensrettend sein. Unerfahrene Untersucher stellen hierbei aber einen wesent- lichen Faktor für Komplikationen oder den Behandlungserfolg dar. Um die Perikardpunktion zu optimieren, wurde im Rahmen einer experimentellen Untersuchung die neue Technik unter Verwendung eines elektromagnetischen Nadel Tracking Systems validiert. Hierzu wurde zunächst ein Modell entwickelt um die Punktionsgenauigkeit des Systems abhängig von seinen Einflussgrößen möglichst exakt beurteilen zu können. Es zeigte sich, dass das Punktionsergebnis von mehreren Faktoren wie Punktionswinkel, -seite, Ultraschallebene, Abstand zum Ziel und Vorhandensein von Metallgegenständen abhängt. Des Weiteren wurde ein realitätsnahes Perikardpunktionsmodell verwendet. An diesem Modell wurden Perikardergüsse unterschiedlicher Größe simuliert und anschließend Punktionen mit der Nadel durchgeführt. Im BluePhantomTM Modell wurden mithilfe des Nadel Tracking Systems von unerfahrenen Untersuchern Trefferquoten zwischen 80 und 100% erreicht, unabhängig von der Ergussgröße. Anatomisch orientierte Punktionen erreichten hingegen nur Trefferquoten zwischen 11 und 44% bei einer Ergussmenge von 250 ml (bzw. 60-80% bei 450 ml). Das getestete Nadel Tracking System könnte somit zur Verbesserung der Perikardpunktionen beitragen. Für eine abschließende Bewertung ist eine Validierung der Methode unter klinischen Bedingungen möglich. / In addition to diagnostic applications, pericardiocentesis is mainly applied in emergency situations, such as a pericardial tamponade, and can then be life-saving. However, inexperienced examiners represent an essential risk factor for complications or the missing success of treatment. In order to optimize the procedure of pericardiocentesis, we experimentally validated an electromagnetic needle tracking system. For this purpose, we developed a model to assess the puncture accuracy of the system. We identified several factors that affect the accuracy of the system including puncture angle and side, ultrasound plane, distance to the target, and presence of metal objects. Furthermore, we used the BluePhantomTM pericardiocentesis model, which provides a realistic clinical scenario. In this model, we simulated pericardial effusions of different sizes and evaluated success rates for different pericardiocentesis techniques. The success rates for the needle tracking system ranged between 80 and 100%, which were achieved by inexperienced examiners regardless of the effusion size. In contrast, anatomically oriented punctures led to success rates between 11 and 44% with an effusion size of 250 ml (or 60-80% for 450 ml). Overall, the tested needle tracking system could thus contribute to the improvement of pericardiocentesis in clinical prectice. For a final evaluation, a validation of the method under clinical conditions is possible.

As matrizes acelulares são utilizadas na engenharia de tecidos com o objetivo da reconstrução ou substituição de tecidos danificados. Nesse trabalho matrizes acelulares foram preparadas a partir de pericárdio porcino e pericárdio bovino, por possuírem uma grande quantidade colágeno tipo I, usando-se ao tratamento de hidrólise alcalina nos tempos de 12 e 24 horas. Essas matrizes foram desenvolvidas para serem utilizadas como barreiras de proteção no processo de cicatrização de feridas como também na indução de formação de tecidos ósseos. Foram submetidas ao teste de biocompatibilidade in vivo, com a implantação das matrizes no subcutâneo de 65 ratos Wistar, machos, adultos que sofreram eutanásia aos 7, 14, 21, 28 e 35 dias de pós-operatório. A avaliação microscópica no 7º dia mostrou existência da matriz e uma grande quantidade de infiltrado inflamatório em volta do material, sendo que ao 14º dias além do infiltrado inflamatório, foi observado uma neovascularização. Aos 21º e 28º dias foi observado uma diminuição gradual do infiltrado inflamatório, crescimento celular no local em que as fendas se formaram nas matrizes e uma grande revascularização. Ao 35º dias a matriz de pericárdio bovino e porcino foram reabsorvidas totalmente. Comparando o pericárdio bovino com o porcino tratado por 12 e 24 horas em relação ao tempo de degradação, foi observado que as matrizes tanto bovina como a porcina tratadas por 24 horas degradaram mais rápido que as tratadas por 12 horas. Portanto as matrizes de pericárdio bovino e porcino são biocompativeis, pois não causaram reações citotóxicas, reações inflamatórias e nem imunológica adversa. / Acellular matrices are used in tissue engineering for reconstruction or replacement of damaged tissues .In this study acellular matrices were developed using porcine pericardium and bovine pericardium, which contain a large quantity of type I collagen, using an alkaline hydrolysis treatment at the times of 12 hours and 24 hours. The matrices were developed to be used as protective barriers in the process of wound healing, and also in bone tissue inducing formation. In the test of in vivo biocompatibility, matrices were implanted subcutaneously in 65 adult male Wistar rats, sacrificed at 7, 14, 21, 28 and 35 days postoperatively. The microscopic evaluation on day 7 showed a large amount of inflammatory infiltrate around the material; at the 14th day, beyond the inflammatory infiltrate was observed a neovascularization. At 21st and 28th days were observed a gradual decrease in the inflammatory infiltrate, cellular growth and a large neovascularization. By day 35, porcine and bovine pericardium matrices were completely resorbed. Comparing the degradation time between the matrices treated with 12 and 24 hours, it was observed that both matrices treated for 24 h, degraded faster than those treated for 12 hours. Both matrices are biocompatible, do not cause cytotoxic reactions, inflammatory or immune adverse reactions.

As matrizes acelulares são utilizadas na engenharia de tecidos com o objetivo da reconstrução ou substituição de tecidos danificados. Nesse trabalho matrizes acelulares foram preparadas a partir de pericárdio porcino e pericárdio bovino, por possuírem uma grande quantidade colágeno tipo I, usando-se ao tratamento de hidrólise alcalina nos tempos de 12 e 24 horas. Essas matrizes foram desenvolvidas para serem utilizadas como barreiras de proteção no processo de cicatrização de feridas como também na indução de formação de tecidos ósseos. Foram submetidas ao teste de biocompatibilidade in vivo, com a implantação das matrizes no subcutâneo de 65 ratos Wistar, machos, adultos que sofreram eutanásia aos 7, 14, 21, 28 e 35 dias de pós-operatório. A avaliação microscópica no 7º dia mostrou existência da matriz e uma grande quantidade de infiltrado inflamatório em volta do material, sendo que ao 14º dias além do infiltrado inflamatório, foi observado uma neovascularização. Aos 21º e 28º dias foi observado uma diminuição gradual do infiltrado inflamatório, crescimento celular no local em que as fendas se formaram nas matrizes e uma grande revascularização. Ao 35º dias a matriz de pericárdio bovino e porcino foram reabsorvidas totalmente. Comparando o pericárdio bovino com o porcino tratado por 12 e 24 horas em relação ao tempo de degradação, foi observado que as matrizes tanto bovina como a porcina tratadas por 24 horas degradaram mais rápido que as tratadas por 12 horas. Portanto as matrizes de pericárdio bovino e porcino são biocompativeis, pois não causaram reações citotóxicas, reações inflamatórias e nem imunológica adversa. / Acellular matrices are used in tissue engineering for reconstruction or replacement of damaged tissues .In this study acellular matrices were developed using porcine pericardium and bovine pericardium, which contain a large quantity of type I collagen, using an alkaline hydrolysis treatment at the times of 12 hours and 24 hours. The matrices were developed to be used as protective barriers in the process of wound healing, and also in bone tissue inducing formation. In the test of in vivo biocompatibility, matrices were implanted subcutaneously in 65 adult male Wistar rats, sacrificed at 7, 14, 21, 28 and 35 days postoperatively. The microscopic evaluation on day 7 showed a large amount of inflammatory infiltrate around the material; at the 14th day, beyond the inflammatory infiltrate was observed a neovascularization. At 21st and 28th days were observed a gradual decrease in the inflammatory infiltrate, cellular growth and a large neovascularization. By day 35, porcine and bovine pericardium matrices were completely resorbed. Comparing the degradation time between the matrices treated with 12 and 24 hours, it was observed that both matrices treated for 24 h, degraded faster than those treated for 12 hours. Both matrices are biocompatible, do not cause cytotoxic reactions, inflammatory or immune adverse reactions.

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy