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Introduction Gel permeation chromatography (GPC), also referred to as size exclusion chromatography (SEC), when applied to polyolefins analysis (Polyethylene. PE and Polypropylene, PP) has been considered a demanding task due [...]

La matrona es el profesional sanitario de referencia en relación con el cuidado de la mujer, y su acceso y formación viene regulada a nivel internacional, europeo y español.

Dos hermanas de 54 y 60años, con antecedentes de diabetes y sordera, consultaron por disminución de la agudeza visual (AV). En la funduscopia se observaban áreas parcheadas de atrofia coriorretiniana con disposición anular alrededor de la fóvea. El estudio genético identificó la mutación heteroplásmica 3243A>G en el ADN mitocondrial, compatible con el síndrome Maternally Inherited Diabetes and Deafness(MIDD) o enfermedad de Ballinger-Wallace.

AbstractIt is well known that there are 17 crystallographic groups that determine the possible tessellations of the Euclidean plane. We approach them from an unusual point of view. Corresponding to each crystallographic group there is an orbifold. We show how to think of the orbifolds as artifacts that serve to create tessellations.

Summary:An infrared detector based on a set of narrow band optical filters was coupled to a high temperature Gel Permeation Chromatograph (GPC) producing continuous chromatograms of absorbance after the molar mass fractionation. A multiple linear regression (MLR) model was established to relate the measured absorbance to the average octene weight percent in industrial ethylene‐octene copolymer samples. This method is compared to univariate and multivariate band ratio models. The application of these models to produce molar mass compositional distributions is also outlined.

Summary. Transglutaminases have a range of catalytic activities, most of which concern the post-translational modification of proteins. The most important of these activities, both in terms of biology and biotechnology, is the cross-linking of proteins into large supramolecular networks. The widespread use of transglutaminases in research, medicine and industry has increased the demand for an inexpensive, efficient and safe source of recombinant enzymes. We describe initial results concerning the production of a mammalian transglutaminase in transgenic rice plants as a first step towards the large-scale molecular farming of this enzyme.

Transglutaminases have a range of catalytic activities, most of which concern the post-translational modification of proteins. The most important of these activities is the cross-linking of proteins into large supramolecular networks. The widespread use of transglutaminases has increased the demand for an inexpensive, efficient and safe source of recombinant enzyme. We explored the use of plant-based systems for the production of this important industrial enzyme. Transgenic rice plants engineered with a rat prostate transglutaminase (rTGp), driven by the strong constitutive maize-1 ubiquitin promoter and its first intron, were shown to express the recombinant enzyme at the mRNA and protein levels. The Ca2+dependence of the recombinant enzyme was confirmed by the biotin-labelled cadaverine-incorporation assay. In this communication we report the molecular and biochemical characterisation of transgenic plants expressing rTGpand this sets the stage for establishing a bioreactor system for the production of transglutaminases in plants.

The production of lipase by Candida rugosa in batch cultures was studied. The initial concentration of the carbon source employed, oleic acid, had an important effect on the final lipolytic activity levels. The maximum lipase/substrate yield and specific productivity obtained correspond to an initial oleic acid concentration of 2 g/l. At higher concentrations, up to 8 g/l oleic acid, specific productivity decreased. Lipase production was not observed below 1 g/l oleic acid. Lipase inactivation in culture broth due to surface forces and shear stress at the gas/liquid interface was not observed. There was no shear stress denaturation at stirring rates of 250, 500 and 750 rpm. No temperature inactivation was detected up to 50° C. Two different lipases with a similar molecular weight of 60kDa were purified from culture broth.

Simulation studies have predicted that maximum lipase activity is reached with fed-batch operation strategies. In this work, two different fed-batch operational strategies have been studied: constant substrate feeding rate and specific growth rate control. A constant substrate feeding rate strategy showed that maximum aqueous lipolytic activity (55 U/mL) was reached at low substrate feeding rates, whereas lipase tends to accumulate inside the cell at higher rates of substrate addition. In the second fed-batch strategy studied, a feedback control strategy has been developed based on the estimation of state variables (X and μ) from the measurement of indirect variables such as CER by means of mass spectrometry techniques. An on-off controller was then used to maintain the specific growth rate at the desired value by adjusting the substrate feeding rate. A constant specific growth rate strategy gave higher final levels of aqueous lipolytic activity (117 U/mL) at low specific growth rates. At higher specific growth rates the enzyme remained accumulated inside the cell, as was observed with a constant feeding fed-batch strategy. With a constant specific growth rate strategy, lipase production by Candida rugosa was enhanced 10-fold compared to a batch operation. Purification studies have demonstrated that lipolytic and esterasic specific activity ratios of Candida rugosa isoenzymes can be modified by using different operational conditions. These studies have also showed that the isoenzymes obtained in a controlled growth rate strategy are around three- to four-fold more active than those obtained in a constant feeding rate strategy. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 156–168, 1998.

To prospectively analyze factors that influence peripheral blood stem cell (PBSC) collection and hematopoietic recovery after high-dose chemotherapy (HDC), 39 patients received cyclophosphamide 4 g/m2and rHuG-CSF (Filgrastim) 5 μg/kg/day. Leukapheresis was started when CD34+cells/mL were > 5 × 103. A minimum of 2 × 106CD34+cells/kg was collected. Median steady-state bone marrow CD34+cell percentage was 0.8% (range, 0.1 to 6). Thirtytwo patients received HDC with autologous PBSC transplantation plus Filgrastim.A median of 2 (range, 0 to 6) leukapheresis per patient were performed and a median of 6.3 × 106CD34+cells/kg (range, 0 to 44.4) collected; four patients failed to mobilize CD34+cells. The number of cycles of prior chemotherapy had an inverse correlation with the number CD34+cells/kg collected (r =—0.38; p< 0.005). Patients with <7 cycles had a higher predictability for onset of leukapheresis than patients with 37 (93% versus 50%; p< 0.005). The four patients who failed to mobilize had received ≥7 cycles. The number of CD34+cells/kg infused after HDC had an inverse correlation with days to recovery to 0.5 × 109neutrophils/L and 20 X 109platelets/L (r =—0.68 and—0.56; p< 0.005). The effect of these factors on mobilization and hematopoietic recovery were confirmed by multivariate analysis. Requirements for supportive measures were significantly lower in patients given a higher dose of CD34+cells/kg.Therefore, PBSC collection should be planned early in the course of chemotherapy. Larger number of CD34+cells/kg determined a more rapid hematopoietic recovery and a decrease of required supportive measures.

Oleic acid has been reported as a good inducer of lipase production by Candida rugosa. In order to know if this enzyme is induced by oleic acid itself or by a metabolite, different short chain fatty acids were tested. Butyric acid was the best carbon source to growth microorganism but it did not induce lipase production. Although caprylic and capric acid were the best inducers of lipase production, at concentrations up 1 g/l they have toxic effect in Candida rugosagrowth. Thus, from the point of view of industrial production oleic acid could be considered as the best substrate tested.

Fermentation applications of mass spectrometer (Spectramass PC2000) hampered by interface and software difficulties have been successfully solved. A multiplexed exhaust gas analysis, data acquisition and estimation system was designed and implemented. An specific software was developed in C+ + language programming. This system was tested for lipase production by Candida rugosain batch fermentation.

The interaction between medium components, microorganisms and the operational mode to produce lipase byCandida rugosawas studied. It has been observed as an emulsion formation between oleic acid and urea during continuous culture. Because of this emulsion, the nitrogen source cannot be assimilated by the cells. The lack of nitrogen source provoked a decrease in protein synthesis, being lipase synthesis suppressed. The change of the nitrogen source from urea to ammonium sulfate avoided the emulsion formation, allowing to reach biomass and lipase steady states in continuous cultures. In batch cultures, no effect of nitrogen source on lipase production and biomass was observed. The specific productivity in continuous culture was slightly higher than in batch cultures.