Efecto de la sacarosa en la producción de celulosa por Gluconacetobacter xylinus en cultivo estático

RESUMEN Objetivo. Determinar el efecto de sacarosa en la productividad de BC por Gluconacetobacter xylinus IFO 13693 en condición estática. Materiales y métodos. La síntesis de celulosa bacteriana (BC) por Gluconacetobacter xylinus se llevo a cabo en un cultivo estático discontinuo a temperatura ambiente, en presencia de sacarosa como la principal fuente de carbono a concentraciones iniciales de 0.8 a 7.6 % (p/v). Las concentraciones remanentes de BC, sacarosa, glucosa y fructosa se determinaron cada semana. Para la cinética de la hidrólisis de la sacarosa y formación de celulosa y el coeficiente de rendimiento del producto se utilizo el software Microcal Origin 6.0®. Resultados. En la cuarta semana los valores de BC se encontraron entre 32.5 a 39.5 g/L para las diferentes concentraciones de sacarosa. La cinética para la hidrólisis de sacarosa se ajusta al modelo de Michaelis-Menten, con una Vmax de 0.0002 mol L-1 h-1 y Km de 0.018 M. La producción de BC se ajusta al modelo propuesto por Marx-Figini y Pion, con un valor de la pendiente (kc), entre 0.0018 y 0.0024 h-1 para las diferentes concentraciones iniciales de sacarosa. Los coeficientes de rendimiento tienen valores de 0.8 a 2.4 g de BC producida/g de sacarosa consumida. Conclusiones. La hidrólisis de sacarosa, el consumo de glucosa y fructosa se refleja en la síntesis de celulosa. La hidrólisis de sacarosa y la producción de BC se ajustan a los modelos de Michaelis-Menten y al propuesto por Marx-Figini y Pion, respectivamente. Finalmente, el rendimiento depende de la concentración de sacaros

Enhancement of immune response of HBsAg loaded poly(L-lactic acid) microspheres against Hepatitis B through incorporation of alum and chitosan

Purpose: Poly (L-lactic acid) (PLA) microparticles encapsulating Hepatitis B surface antigen (HBsAg) with alum and chitosan were investigated for their potential as a vaccine delivery system. Methods: The microparticles, prepared using a water-in-oil-in-water (w/o/w) double emulsion solvent evaporation method with polyvinyl alcohol (PVA) or chitosan as the external phase stabilising agent showed a significant increase in the encapsulation efficiency of the antigen. Results: PLA-Alum and PLA-chitosan microparticles induced HBsAg serum specific IgG antibody responses significantly higher than PLA only microparticles and free antigen following subcutaneous administration. Chitosan not only imparted a positive charge to the surface of the microparticles but was also able to increase the serum specific IgG antibody responses significantly. Conclusions: The cytokine assays showed that the serum IgG antibody response induced is different according to the formulation, indicated by the differential levels of interleukin 4 (IL-4), interleukin 6 (IL-6) and interferon gamma (IFN-γ). The microparticles eliciting the highest IgG antibody response did not necessarily elicit the highest levels of the cytokines IL-4, IL-6 and IFN-γ

Preparation and Evaluation of Poly(Ethylene Glycol)–Poly(Lactide) Micelles as Nanocarriers for Oral Delivery of Cyclosporine A

A series of monomethoxy poly(ethylene glycol)–poly(lactide) (mPEG–PLA) diblock copolymers were designed according to polymer–drug compatibility and synthesized, and mPEG–PLA micelle was fabricated and used as a nanocarrier for solubilization and oral delivery of Cyclosporine A (CyA). CyA was efficiently encapsulated into the micelles with nanoscaled diameter ranged from 60 to 96 nm with a narrow size distribution. The favorable stabilities of CyA-loaded polymeric micelles were observed in simulated gastric and intestinal fluids. The in vitro drug release investigation demonstrated that drug release was retarded by polymeric micelles. The enhanced intestinal absorption of CyA-loaded polymeric micelles, which was comparable to the commercial formulation of CyA (Sandimmun Neoral®), was found. These suggested that polymeric micelles might be an effective nanocarrier for solubilization of poorly soluble CyA and further improving oral absorption of the drug

Synthetic Nanoparticles for Vaccines and Immunotherapy

The immune system plays a critical role in our health. No other component of human physiology plays a decisive role in as diverse an array of maladies, from deadly diseases with which we are all familiar to equally terrible esoteric conditions: HIV, malaria, pneumococcal and influenza infections; cancer; atherosclerosis; autoimmune diseases such as lupus, diabetes, and multiple sclerosis. The importance of understanding the function of the immune system and learning how to modulate immunity to protect against or treat disease thus cannot be overstated. Fortunately, we are entering an exciting era where the science of immunology is defining pathways for the rational manipulation of the immune system at the cellular and molecular level, and this understanding is leading to dramatic advances in the clinic that are transforming the future of medicine.1,2 These initial advances are being made primarily through biologic drugs– recombinant proteins (especially antibodies) or patient-derived cell therapies– but exciting data from preclinical studies suggest that a marriage of approaches based in biotechnology with the materials science and chemistry of nanomaterials, especially nanoparticles, could enable more effective and safer immune engineering strategies. This review will examine these nanoparticle-based strategies to immune modulation in detail, and discuss the promise and outstanding challenges facing the field of immune engineering from a chemical biology/materials engineering perspectiveNational Institutes of Health (U.S.) (Grants AI111860, CA174795, CA172164, AI091693, and AI095109)United States. Department of Defense (W911NF-13-D-0001 and Awards W911NF-07-D-0004

Efecto de la sacarosa en la producción de celulosa por Gluconacetobacter xylinus en cultivo estático

Objective. Determine the effect of sucrose on the productivity of BC by Gluconacetobacter xylinus IFO 13693 in static condition. Materials and methods. The synthesis of bacterial cellulose (BC) by Gluconacetobacter xylinus was carried out in a discontinuous static culture at room temperature, in the presence of sucrose as the main carbon source at initial concentrations of 0.8 to 7.6% (p/v). The residual concentrations of BC, sucrose, glucose and fructose were measured every week. The Microcal Origin 6.0®. Software used to determine the kinetics of hydrolysis of sucrose and formation of cellulose and the coefficient of performance of the product Results. In the fourth week the BC values were between 32.5 to 39.5 g/L for the different concentrations of sucrose. The kinetics for the hydrolysis of sucrose fits the Michaelis-Menten model, with a Vmax of 0.0002 mol L-1 h-1 and Km of 0.018 M. The production of BC follows the model proposed by Marx-Figini and Pion, with a value of the slope (kc) between 0.0018 and 0.0024 h-1 for different initial concentrations of sucrose. The yield coefficients have values of 0.8 to 2.4 g of BC produced / g of sucrose consumed. Conclusions. The hydrolysis of sucrose, fructose consumption and glucose is reflected in cellulose synthesis. The hydrolysis of sucrose and production of BC fit the Michaelis-Menten model and the model proposed by Marx-Figini and Pion, respectively. Finally, the performance depends on the concentration of sucrose.Objetivo. Determinar el efecto de sacarosa en la productividad de BC por Gluconacetobacter xylinus IFO 13693 en condición estática. Materiales y métodos. La síntesis de celulosa bacteriana (BC) por Gluconacetobacter xylinus se llevo a cabo en un cultivo estático discontinuo a temperatura ambiente, en presencia de sacarosa como la principal fuente de carbono a concentraciones iniciales de 0.8 a 7.6 % (p/v). Las concentraciones remanentes de BC, sacarosa, glucosa y fructosa se determinaron cada semana. Para la cinética de la hidrólisis de la sacarosa y formación de celulosa y el coeficiente de rendimiento del producto se utilizo el software Microcal Origin 6.0®. Resultados. En la cuarta semana los valores de BC se encontraron entre 32.5 a 39.5 g/L para las diferentes concentraciones de sacarosa. La cinética para la hidrólisis de sacarosa se ajusta al modelo de Michaelis-Menten, con una Vmax de 0.0002 mol L-1 h-1 y Km de 0.018 M. La producción de BC se ajusta al modelo propuesto por Marx-Figini y Pion, con un valor de la pendiente (kc), entre 0.0018 y 0.0024 h-1 para las diferentes concentraciones iniciales de sacarosa. Los coeficientes de rendimiento tienen valores de 0.8 a 2.4 g de BC producida/g de sacarosa consumida. Conclusiones. La hidrólisis de sacarosa, el consumo de glucosa y fructosa se refleja en la síntesis de celulosa. La hidrólisis de sacarosa y la producción de BC se ajustan a los modelos de Michaelis-Menten y al propuesto por Marx-Figini y Pion, respectivamente. Finalmente, el rendimiento depende de la concentración de sacarosa

Cities, skills, and regional change

One approach to urban areas emphasizes the existence of certain immutable relationships, such as Zipf's or Gibrat's Law. An alternative view is that urban change reflects individual responses to changing tastes or technologies. This paper examines almost 200 years of regional change in the U.S. and finds that few, if any, growth relationships remain constant, including Gibrat's Law. Education does a reasonable job of explaining urban resilience in recent decades, but does not seem to predict county growth a century ago. After reviewing this evidence, we present and estimate a simple model of regional change, where education increases the level of entrepreneurship. Human capital spillovers occur at the city level because skilled workers produce more product varieties and thereby increase labor demand. We find that skills are associated with growth in productivity or entrepreneurship, not with growth in quality of life, at least outside of the West. We also find that skills seem to have depressed housing supply growth in the West, but not in other regions, which supports the view that educated residents in that region have fought for tougher land-use controls. We also present evidence that skills have had a disproportionately large impact on unemployment during the current recession

Cities, skills, and regional change

One approach to urban areas emphasizes the existence of certain immutable relationships, such as Zipf's or Gibrat's Law. An alternative view is that urban changereflects individual responses to changing tastes or technologies. This paper examinesalmost 200 years of regional change in the U.S. and finds that few, if any, growth relationships remain constant, including Gibrat's Law. Education does a reasonable jobof explaining urban resilience in recent decades, but does not seem to predict countygrowth a century ago. After reviewing this evidence, we present and estimate a simple model of regional change, where education increases the level of entrepreneurship.Human capital spillovers occur at the city level because skilled workers produce moreproduct varieties and thereby increase labor demand. We find that skills are associatedwith growth in productivity or entrepreneurship, not with growth in quality of life, atleast outside of the West. We also find that skills seem to have depressed housing supplygrowth in the West, but not in other regions, which supports the view that educatedresidents in that region have fought for tougher land-use controls. We also present evidence that skills have had a disproportionately large impact on unemployment duringthe current recession