No description available.

A two-stage process is proposed that is based on the biological production of H2S from organic waste and its subsequent overall conversion to H2 via an exothermic reaction. The current study examined the first step of this process, namely, the design and operation of a packed bed bioreactor with high volumetric H2S production (mol/m3.d) and its comparison to analogous methanogenic technology. A novel method of inoculum design was developed by evaluating the kinetics and immobilization potential of Desulfovibrio desulfuricans (ATCC 7757) and a sulfate reducing bacteria (SRB) consortium. The consortium’s kinetics, as measured by the specific rate of sulfate reduction (1.2 g SO42-/g CDW.h), were approximately twice as fast as those of D. desulfuricans. The pure strain however exhibited superior immobilization potential. Studies revealed that a mixed inoculum containing 96 % D. desulfuricans and 4 % consortium facilitated the rapid immobilization of a highly active SRB biomass and contributed to improved bioreactor performance. Diatomaceous earth (DE) pellets, porous glass beads, polyurethane foam, and bone char were evaluated as potential carrier materials for SRB immobilization. The DE pellets immobilized the most biomass, were well suited for use at the industrial scale, and were thus employed in all continuous flow bioreactor experiments. Using the designed inoculum and DE pellets, a 615 mL bioreactor achieved a volumetric productivity of 493 mol H2S/m3.d (at D = 1.6 h-1) and a dissolved sulfide concentration of 9.9 mM. This occurred after 8 d of operation and represents a tenfold reduction in the required start-up period compared to similar bioreactors in the literature. An N2 strip gas was later used to remove the dissolved sulfide to the gas phase and enhance sulfate conversion. Shifting the medium pH from 7 to 6 increased the fraction of strippable sulfide and improved the strip gas composition from 3.6 to 5.8 mol % H2S. The strip gas to liquid feed ratio (G/L, m3/m3) was investigated in the range of 0-14 and was found to be a suitable basis for scale-up indicating that productivities of up to 830 mol/m3.d were readily achievable. This represents a considerable improvement over current methanogenic bioreactor productivities. / Thesis (Master, Chemical Engineering) -- Queen's University, 2007-09-23 16:44:22.443

No description available.

Thesis (Ph.D.)--Tennessee Technological University, 2006. / Bibliography: leaves 590-601.

A Prolactina (PRL) é um dos hormônios mais versáteis em termos de ação biológica. Sua ação mais conhecida está relacionada com o estímulo da lactação e regulação do crescimento e da diferenciação da glândula mamária; também apresenta importante aplicação diagnóstica. Somando os crescentes estudos sobre suas possíveis aplicações terapêuticas, fica cada vez mais notória a necessidade da obtenção desse hormônio puro, biologicamente ativo e na sua forma autêntica.O objetivo fundamental desse projeto foi a produção de hPRL em escala laboratorial a partir de bactérias (E.coli) modificadas geneticamente, utilizando um sistema de expressão baseado no promotor Lambda () PL, o mesmo utilizado com sucesso em nosso laboratório na expressão do hGH. Descrevemos nesse trabalho um processo de cultivo em biorreator, onde não foi utilizado o repressor cIts, uma proteína termo-sensível que usualmente é utilizada para inibir o funcionamento do promotor PL durante crescimento a 30ºC. O processo de cultivo apresenta basicamente três etapas: na primeira etapa o crescimento é realizado sem adição contínua de nutrientes (cultivo em batch), na segunda etapa ocorre adição contínua de nutrientes e carboidrato (cultivo em fed-batch) e na última etapa é realizada a ativação, caracterizada pelo aumento da temperatura mantendo-se a adição de nutrientes e carboidrato. Esse processo de fermentação rápido e flexível, com duração média de 20 horas, permitiu obter uma biomassa final correspondente à densidade óptica de aproximadamente 30 A600nm (unidades ópticas de absorbância em 600nm) e com uma expressão da ordem de 1g de hPRL mL-1 A600 -1, as mais altas já relatadas para secreção de prolactina no espaço periplásmico. A hPRL monomérica foi purificada e caracterizada por métodos físico-químicos e biológicos, os quais confirmaram a sua atividade biológica e imunológica, o seu correto processamento e uma massa molecular relativa (Mr) de 22.906. / Prolactin (PRL) is one of the most versatile hormones in terms of biological action. His best known action is related to the stimulation of lactation and regulation of growth and differentiation of the mammary gland; it also has wide important diagnostic applications. Considering all the increasing studies on its potential therapeutic applications, the need for obtaining this hormone in its pure, biologically active and authentic form becomes clearer and clearer. The fundamental objective of this project was the production of hPRL on the laboratory scale, from genetically modified bacteria (E.coli), using an expression system based on Lambda () PL promoter, the same successfully used in our laboratory for the expression of hGH. We set up a cultivation process in bioreactor, where the repressor (cIts), a thermo-sensitive protein that is usually used to inhibit the PL promoter during the growth phase (30°C). The cultivation process presents basically three stages: the first step in was not used the growth is carried out without the continuous addition of nutrients (batch cultivation), the second step in which a continuous addition of nutrients and carbohydrate occurs (fed-batch cultivation) and a final step when activation is carried out. The latter is characterized by an increased temperature, still maintaining the addition of nutrients and carbohydrate. This fast and flexible process of fermentation, with the average duration of 20 hours, led to a final biomass of approximately 30 A600nm (units of optical absorbance at 600nm), with the expression of about 1g of hPRL mL-1A600 -1, the highest ever reported for the secretion of prolactin in the periplasmic space. Monomeric hPRL was purified and characterized by physical-chemical methods and biological assays, which confirmed its biological and immunological activity, correct processing and a relative molecular mass (Mr) of 22,906.

A Prolactina (PRL) é um dos hormônios mais versáteis em termos de ação biológica. Sua ação mais conhecida está relacionada com o estímulo da lactação e regulação do crescimento e da diferenciação da glândula mamária; também apresenta importante aplicação diagnóstica. Somando os crescentes estudos sobre suas possíveis aplicações terapêuticas, fica cada vez mais notória a necessidade da obtenção desse hormônio puro, biologicamente ativo e na sua forma autêntica.O objetivo fundamental desse projeto foi a produção de hPRL em escala laboratorial a partir de bactérias (E.coli) modificadas geneticamente, utilizando um sistema de expressão baseado no promotor Lambda () PL, o mesmo utilizado com sucesso em nosso laboratório na expressão do hGH. Descrevemos nesse trabalho um processo de cultivo em biorreator, onde não foi utilizado o repressor cIts, uma proteína termo-sensível que usualmente é utilizada para inibir o funcionamento do promotor PL durante crescimento a 30ºC. O processo de cultivo apresenta basicamente três etapas: na primeira etapa o crescimento é realizado sem adição contínua de nutrientes (cultivo em batch), na segunda etapa ocorre adição contínua de nutrientes e carboidrato (cultivo em fed-batch) e na última etapa é realizada a ativação, caracterizada pelo aumento da temperatura mantendo-se a adição de nutrientes e carboidrato. Esse processo de fermentação rápido e flexível, com duração média de 20 horas, permitiu obter uma biomassa final correspondente à densidade óptica de aproximadamente 30 A600nm (unidades ópticas de absorbância em 600nm) e com uma expressão da ordem de 1g de hPRL mL-1 A600 -1, as mais altas já relatadas para secreção de prolactina no espaço periplásmico. A hPRL monomérica foi purificada e caracterizada por métodos físico-químicos e biológicos, os quais confirmaram a sua atividade biológica e imunológica, o seu correto processamento e uma massa molecular relativa (Mr) de 22.906. / Prolactin (PRL) is one of the most versatile hormones in terms of biological action. His best known action is related to the stimulation of lactation and regulation of growth and differentiation of the mammary gland; it also has wide important diagnostic applications. Considering all the increasing studies on its potential therapeutic applications, the need for obtaining this hormone in its pure, biologically active and authentic form becomes clearer and clearer. The fundamental objective of this project was the production of hPRL on the laboratory scale, from genetically modified bacteria (E.coli), using an expression system based on Lambda () PL promoter, the same successfully used in our laboratory for the expression of hGH. We set up a cultivation process in bioreactor, where the repressor (cIts), a thermo-sensitive protein that is usually used to inhibit the PL promoter during the growth phase (30°C). The cultivation process presents basically three stages: the first step in was not used the growth is carried out without the continuous addition of nutrients (batch cultivation), the second step in which a continuous addition of nutrients and carbohydrate occurs (fed-batch cultivation) and a final step when activation is carried out. The latter is characterized by an increased temperature, still maintaining the addition of nutrients and carbohydrate. This fast and flexible process of fermentation, with the average duration of 20 hours, led to a final biomass of approximately 30 A600nm (units of optical absorbance at 600nm), with the expression of about 1g of hPRL mL-1A600 -1, the highest ever reported for the secretion of prolactin in the periplasmic space. Monomeric hPRL was purified and characterized by physical-chemical methods and biological assays, which confirmed its biological and immunological activity, correct processing and a relative molecular mass (Mr) of 22,906.

No description available.

Developing an optimized growth environment for adipose-derived stems cells (ASCs) to obtain clinically useable cell quantities from relatively small tissue biopsies would significantly impact the field of tissue engineering. To date, ASCs have been differentiated into adipose, bone, cartilage, smooth muscle, endothelial, skeletal muscle, nervous, and cardiac tissue. Therefore, ASCs have potential for use in the treatment of a wide variety of clinical conditions ranging from myocardial infarction, to musculoskeletal disorders, and the repair of soft tissue defects. In this work, a custom-designed, 3-dimensional (3-D) scaffold-based perfusion bioreactor system was investigated in the culture of ASCs. Decellularized adipose tissue (DAT) was used to provide a 3-dimensional scaffold, as it possesses the native extracellular matrix (ECM) architecture and composition of human adipose tissue. The DAT had a permeability of 149 m2, based on a perfusion rate of 1.5 mL/min over a 200 mg DAT sample, and the culturing medium was evenly perfused throughout the DAT, thereby permitting possible cell growth within the central regions. Initial culturing studies of human ASCs on tissue culture polystyrene (TCPS) demonstrated that hypoxic (5% O2) conditions decreased the doubling time, and resulted in enhanced cell proliferation, as compared to normoxic (21% O2) conditions. The cell imaging and DNA quantification results showed that suspension seeding of the ASCs permitted cell attachment to the DAT scaffold, but did not support long-term ASC growth. In contrast, when the ASCs were seeded as multicellular aggregates, the cells attached and underwent measurable proliferation. The optimal seeding density observed was 1 x 106 ASCs/scaffold; or 50 aggregates (20,000 ASCs/aggregate) per scaffold. Based on the confocal imaging, the ASCs remained spherical in morphology during the entire culturing period. Moreover, results illustrated that the perfusion bioreactor provided an improved culturing environment for ASCs over traditional static culturing. Hypoxic (5% O2) conditions showed improved proliferation over normoxic (21% O2) conditions, within the bioreactor system. After a 14-day hypoxic culturing period in the perfusion bioreactor, the seeded ASCs retained the ability to undergo adipogenesis, as indicated by Glycerol-3-Phsophate Dehydrogenase (GPDH) enzymatic activity measurements, demonstrating the promise of this approach for soft tissue engineering applications / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-11-09 20:28:34.252

Myocardial infarction (MI) and heart failure are leading causes of mortality globally. Recently, cardiac tissue engineering has become an attractive option for MI treatment due to the following advantages: it might provide optimal tissue performance maintained by viable transplanted cells, and might also stimulate the formation of vasculature supplying oxygen and nutrients in the patched region. However, fabrication of a thick viable cardiac patch with 3D scaffolds that are thoroughly recellularized with desired cells remains a challenge. We hypothesize that the decellularized porcine myocardium scaffold can preserve natural extracellular matrix (ECM) structure, cardiomyocyte lacunae, mechanical properties, and vasculature templates that are able to facilitate stem cell reseeding, proliferation, cardiomyocyte differentiation, and angiogenesis. In this dissertation, we have (i) assessed the potential of the decellularized porcine myocardium as a scaffold for thick cardiac patch tissue engineering; (ii) thoroughly characterized the structural and biomechanical properties of the myocardial ECM; (iii) designed and built a novel bioreactor that could provide coordinated mechanical and electrical stimulations, and (iv) evaluated the efficiency of the multi-stimulations on the development of a cardiac tissue construct. An optimized decellularization protocol has been identified to obtain the acellular myocardial scaffold that preserves subtle ECM composition and ultrastructure. We recellularized the acellular scaffold with bone marrow mononuclear cells using a rotating bioreactor and observed successful recellularization with good cell viability, proliferation, and differentiation in a 2-week culture time. Furthermore, we have successfully built a novel bioreactor that is able to provide coordinated mechanical and electrical stimulations for facilitating stem cell differentiation and tissue construct development. We found that cardiomyocyte differentiation and tissue remodeling were more effectively and efficiently promoted with the coordinated simulations, evidenced by good cell viability, proliferation, differentiation, positive tissue remodeling, and a trend of angiogenesis in a short period of time (2 - 4 days). The clinical product that we envision will benefit from the natural architecture of myocardial ECM, which has the potential to promote stem cell differentiation, cardiac regeneration, and angiogenesis. The hopes are that our novel approach will ultimately impact thousands of patients who have suffered significant damage from a prior myocardial infarction.

Bioreactor landfills have become a feasible alternative to the typical "dry tomb" landfill. By recirculating leachate and/or adding additional liquid wastes, bioreactor landfills operate to rapidly degrade and transform organic wastes. The reactions within a bioreactor landfill create elevated temperatures. The intent of this study was to determine the effect of elevated temperature on the degradation of lignocellulose compounds. In order to observe the effects of temperature on lignin, small bioreactors were created in the laboratory. Several experiments were performed by the authors. Solubility of lignin based on temperature and time of thermal exposure were conducted. In addition, degradation studies were conducted based on biological treatment of lignin as well as a combination of biological and thermal treatment. Samples were collected at specified intervals to determine the amount of water soluble lignin (WSL), volatile fatty acids (VFAs), lignin monomers, and/or methane present. Lignin solubility increased as temperature rose in the thermal solubility experiments. The rate of solubility increased 15 times for office paper and 1.5 times for cardboard in the biological experiments when compared to the thermal treatment. The thermal and biological study indicates that as lignin is solubilized, it breaks down into lignin monomers, which can be converted easily by anaerobic bacteria into VFAs and subsequently, methane. These experiments indicate that temperature is crucial to the degradation of lignin compounds in a bioreactor landfill. / Master of Science