The Experts below are selected from a list of 104277 Experts worldwide ranked by ideXlab platform
Kathleen A Derwin - One of the best experts on this subject based on the ideXlab platform.
-
mechanical conditioning of cell seeded small intestine submucosa a potential tissue Engineering Strategy for tendon repair
Tissue Engineering, 2007Co-Authors: Caroline Androjna, Rebecca K Spragg, Kathleen A DerwinAbstract:Our long-term objective is to enhance tendon repair by delivering cells on natural biologic scaffolds to the repair site. Clinical outcomes may be improved by first preconditioning these cell-seede...
-
mechanical conditioning of cell seeded small intestine submucosa a potential tissue Engineering Strategy for tendon repair
Tissue Engineering, 2007Co-Authors: Caroline Androjna, Rebecca K Spragg, Kathleen A DerwinAbstract:Our long-term objective is to enhance tendon repair by delivering cells on natural biologic scaffolds to the repair site. Clinical outcomes may be improved by first preconditioning these cell-seeded constructs in bioreactors to enhance their properties at implantation and to deliver cells expressing a desired phenotype. In this work, we have investigated the effect of in vitro mechanical conditioning on small-intestine submucosa (SIS) scaffolds seeded with primary tendon cells (tenocytes). SIS scaffolds (with and without cells) were conditioned under various loading regimes over a 2-week period. In vitro cyclic loading significantly increased the biomechanical properties (e.g., stiffness) of cell-seeded SIS constructs (129.1 +/- 10.2%) from time 0. The stiffness change of cyclically loaded constructs without cells was 33.9 +/- 13.8% and of statically loaded constructs with cells was 34.0 +/- 15.2% and without cells was 33.4 +/- 10.7%. In the cell-seeded groups, our data demonstrate a direct role (e.g., cell tensioning) for cells in construct stiffening. In addition, the initial stiffness of the cell-seeded, cyclically loaded constructs was found to be a strong predictor of the change in construct stiffness. Despite the mechanical integrity of these constructs being significantly less than native tendon, our data show that structural properties can be improved with in vitro mechanical conditioning. These data provide the basis for future studies investigating in vitro conditioning (mechanical, chemical) of cell-seeded ECM scaffolds and the use of such constructs for enhancing tendon repair in vivo.
Ana M R B Xavier - One of the best experts on this subject based on the ideXlab platform.
-
Adaptation of Scheffersomyces stipitis
Biotechnology for biofuels, 2015Co-Authors: Susana R. Pereira, Violeta Sànchez I Nogué, Cláudio J R Frazão, Luísa S. Serafim, Marie F. Gorwa-grauslund, Ana M R B XavierAbstract:Background Hardwood spent sulfite liquor (HSSL) is a by-product of acid sulfite pulping process that is rich in xylose, a monosaccharide that can be fermented to ethanol by Scheffersomyces stipitis. However, HSSL also contains acetic acid and lignosulfonates that are inhibitory compounds of yeast growth. The main objective of this study was the use of an evolutionary Engineering Strategy to obtain variants of S. stipitis with increased tolerance to HSSL inhibitors while maintaining the ability to ferment xylose to ethanol.
-
adaptation of scheffersomyces stipitis to hardwood spent sulfite liquor by evolutionary Engineering
Biotechnology for Biofuels, 2015Co-Authors: Susana R. Pereira, Violeta Sànchez I Nogué, Cláudio J R Frazão, Luísa S. Serafim, Mariefrancoise Gorwagrauslund, Ana M R B XavierAbstract:Background Hardwood spent sulfite liquor (HSSL) is a by-product of acid sulfite pulping process that is rich in xylose, a monosaccharide that can be fermented to ethanol by Scheffersomyces stipitis. However, HSSL also contains acetic acid and lignosulfonates that are inhibitory compounds of yeast growth. The main objective of this study was the use of an evolutionary Engineering Strategy to obtain variants of S. stipitis with increased tolerance to HSSL inhibitors while maintaining the ability to ferment xylose to ethanol.
Caroline Androjna - One of the best experts on this subject based on the ideXlab platform.
-
mechanical conditioning of cell seeded small intestine submucosa a potential tissue Engineering Strategy for tendon repair
Tissue Engineering, 2007Co-Authors: Caroline Androjna, Rebecca K Spragg, Kathleen A DerwinAbstract:Our long-term objective is to enhance tendon repair by delivering cells on natural biologic scaffolds to the repair site. Clinical outcomes may be improved by first preconditioning these cell-seede...
-
mechanical conditioning of cell seeded small intestine submucosa a potential tissue Engineering Strategy for tendon repair
Tissue Engineering, 2007Co-Authors: Caroline Androjna, Rebecca K Spragg, Kathleen A DerwinAbstract:Our long-term objective is to enhance tendon repair by delivering cells on natural biologic scaffolds to the repair site. Clinical outcomes may be improved by first preconditioning these cell-seeded constructs in bioreactors to enhance their properties at implantation and to deliver cells expressing a desired phenotype. In this work, we have investigated the effect of in vitro mechanical conditioning on small-intestine submucosa (SIS) scaffolds seeded with primary tendon cells (tenocytes). SIS scaffolds (with and without cells) were conditioned under various loading regimes over a 2-week period. In vitro cyclic loading significantly increased the biomechanical properties (e.g., stiffness) of cell-seeded SIS constructs (129.1 +/- 10.2%) from time 0. The stiffness change of cyclically loaded constructs without cells was 33.9 +/- 13.8% and of statically loaded constructs with cells was 34.0 +/- 15.2% and without cells was 33.4 +/- 10.7%. In the cell-seeded groups, our data demonstrate a direct role (e.g., cell tensioning) for cells in construct stiffening. In addition, the initial stiffness of the cell-seeded, cyclically loaded constructs was found to be a strong predictor of the change in construct stiffness. Despite the mechanical integrity of these constructs being significantly less than native tendon, our data show that structural properties can be improved with in vitro mechanical conditioning. These data provide the basis for future studies investigating in vitro conditioning (mechanical, chemical) of cell-seeded ECM scaffolds and the use of such constructs for enhancing tendon repair in vivo.
Susana R. Pereira - One of the best experts on this subject based on the ideXlab platform.
-
Adaptation of Scheffersomyces stipitis
Biotechnology for biofuels, 2015Co-Authors: Susana R. Pereira, Violeta Sànchez I Nogué, Cláudio J R Frazão, Luísa S. Serafim, Marie F. Gorwa-grauslund, Ana M R B XavierAbstract:Background Hardwood spent sulfite liquor (HSSL) is a by-product of acid sulfite pulping process that is rich in xylose, a monosaccharide that can be fermented to ethanol by Scheffersomyces stipitis. However, HSSL also contains acetic acid and lignosulfonates that are inhibitory compounds of yeast growth. The main objective of this study was the use of an evolutionary Engineering Strategy to obtain variants of S. stipitis with increased tolerance to HSSL inhibitors while maintaining the ability to ferment xylose to ethanol.
-
adaptation of scheffersomyces stipitis to hardwood spent sulfite liquor by evolutionary Engineering
Biotechnology for Biofuels, 2015Co-Authors: Susana R. Pereira, Violeta Sànchez I Nogué, Cláudio J R Frazão, Luísa S. Serafim, Mariefrancoise Gorwagrauslund, Ana M R B XavierAbstract:Background Hardwood spent sulfite liquor (HSSL) is a by-product of acid sulfite pulping process that is rich in xylose, a monosaccharide that can be fermented to ethanol by Scheffersomyces stipitis. However, HSSL also contains acetic acid and lignosulfonates that are inhibitory compounds of yeast growth. The main objective of this study was the use of an evolutionary Engineering Strategy to obtain variants of S. stipitis with increased tolerance to HSSL inhibitors while maintaining the ability to ferment xylose to ethanol.
Jean-marc Nicaud - One of the best experts on this subject based on the ideXlab platform.
-
A metabolic Engineering Strategy for producing conjugated linoleic acids using the oleaginous yeast Yarrowia lipolytica
Applied Microbiology and Biotechnology, 2017Co-Authors: Nabila Imatoukene, Jonathan Verbeke, Abdelghani Idrissi Taghki, Claude-Olivier Sarde, Athanasios Beopoulos, Brigitte Thomasset, Maurice Nonus, Jean-marc NicaudAbstract:Conjugated linoleic acids (CLAs) have been found to have beneficial effects on human health when used as dietary supplements. However, their availability is limited because pure, chemistry-based production is expensive, and biology-based fermentation methods can only create small quantities. In an effort to enhance microbial production of CLAs, four genetically modified strains of the oleaginous yeast Yarrowia lipolytica were generated. These mutants presented various genetic modifications, including the elimination of β-oxidation (pox1-6∆), the inability to store lipids as triglycerides (dga1∆ dga2∆ are1∆ lro1∆), and the overexpression of the Y. lipolytica ∆12-desaturase gene (YlFAD2) under the control of the constitutive pTEF promoter. All strains received two copies of the pTEF-oPAI or pPOX-oPAI expression cassettes; PAI encodes linoleic acid isomerase in Propionibacterium acnes. The strains were cultured in neosynthesis or bioconversion medium in flasks or a bioreactor. The strain combining the three modifications mentioned above showed the best results: when it was grown in neosynthesis medium in a flask, CLAs represented 6.5% of total fatty acids and in bioconversion medium in a bioreactor, and CLA content reached 302 mg/L. In a previous study, a CLA degradation rate of 117 mg/L/h was observed in bioconversion medium. Here, by eliminating β-oxidation, we achieved a much lower rate of 1.8 mg/L/h.
-
A metabolic Engineering Strategy for producing conjugated linoleic acids using the oleaginous yeast Yarrowia lipolytica
Applied Microbiology and Biotechnology, 2017Co-Authors: Nabila Imatoukene, Jonathan Verbeke, Claude-Olivier Sarde, Athanasios Beopoulos, Brigitte Thomasset, Maurice Nonus, Abdelghani Idrissi Taghki, Jean-marc NicaudAbstract:Conjugated linoleic acids (CLAs) have been found to have beneficial effects on human health when used as dietary supplements. However, their availability is limited because pure, chemistry-based production is expensive, and biology-based fermentation methods can only create small quantities. In an effort to enhance microbial production of CLAs, four genetically modified strains of the oleaginous yeast Yarrowia lipolytica were generated. These mutants presented various genetic modifications, including the elimination of beta-oxidation (pox1-6a dagger), the inability to store lipids as triglycerides (dga1a dagger dga2a dagger are1a dagger lro1a dagger), and the overexpression of the Y. lipolytica a dagger 12-desaturase gene (YlFAD2) under the control of the constitutive pTEF promoter. All strains received two copies of the pTEF-oPAI or pPOX-oPAI expression cassettes; PAI encodes linoleic acid isomerase in Propionibacterium acnes. The strains were cultured in neosynthesis or bioconversion medium in flasks or a bioreactor. The strain combining the three modifications mentioned above showed the best results: when it was grown in neosynthesis medium in a flask, CLAs represented 6.5% of total fatty acids and in bioconversion medium in a bioreactor, and CLA content reached 302 mg/L. In a previous study, a CLA degradation rate of 117 mg/L/h was observed in bioconversion medium. Here, by eliminating beta-oxidation, we achieved a much lower rate of 1.8 mg/L/h.