bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorophore‐labeled carbohydrate analysis of immunoglobulin fusion proteins: Correlation of oligosaccharide content with in vivo clearance profile
Authors: Flesher Alan R. , Marzowski JoAnne , Wang Wei‐Chun , Raff Howard V. 
Published: December 2004

AbstractCTLA4 is a membrane receptor on cytotoxic T cells whose interaction with the B7 counterreceptor on B cells is important in alloantigen responses. Soluble recombinant human and murine CTLA4 were produced using either Chinese hamster ovary or NS‐0 cell lines. Expression vectors were constructed containing the gene coding for the extracellular domain of CTLA4 fused to either human lgG1 hinge, CH2, and CH3 domains or murine lgG2a hinge, CH2, and CH3 domain genes. These glycoproteins were produced in hollow‐fiber or packed‐bed‐type bioreactors and purified from conditioned media by protein A affinity chromatography. Batches of purified CTLA4lg were analyzed for size, composition, and isoelectric point (pl) patterns by standard protein methods; oligosaccharide and monosaccharide profiles using several carbohydrate specific techniques; and in vivo clearance profiles using a murine model. Significant differences were observed between lots in their pl, clearance, and crbohydrate profiles. Higher overall pl values correlated with accelerated α‐phase clearance and changes in oligosaccharide composition as determined by lectin binding analysis and electrophoresis of fluorophore‐conjugated carbohydrates. Preparations exhibiting slower clearance profiles had oligosaccharides with higher quantities of N‐acetylneuraminic acid and were predominantly of an N‐linked biantennary complex‐type. Conversely, batches with accelerated clearance profiles had less detectable N‐acetylneuraminic acid. Oligosaccharides from murine CTLA4lg produced in NS‐0 cells had terminal N‐glycolylneuraminic acid but no detectable N‐acetylneuraminic acid and had concomitant accelerated clearance. These data suggest that the presence and quantity of N‐acetylneuraminic acid is an important component in predicting CTLA4lg plasma clearance rates and that production lots can be analyzed for oligosaccharide heterogeneity and sialic acid content by electrophoresis of fluorophore‐conjugated carbohydrates. © 1995 John Wiley & Sons, Inc.
Influence of operating variables on liquid circulation in a 10.5‐m3 jet loop bioreactor
Authors: García‐Salas Sergio , Flores‐Cotera Luis B. 
Published: December 2004

AbstractA 10.5‐m3 concentric tube jet loop reactor was used to study the influence of the working liquid volume, mean superficial air velocity, operating pressure, downcomer aeration, liquid jet velocity, and two ratios of draft tube/reactor diameter (Dt/D) on liquid circulation time (Tc). The experiments were carried out in a water–air system with the use of the acid pulse method. Results showed that circulation time was independent of the working liquid volume over a certain minimum liquid level, whereas downcomer aeration and Dt/D ratio appeared as amenable parameters to achieve a high degree of control over liquid circulation and mixing efficiency, and to optimize the overall reactor performance. Increasing the operating pressure caused a reduction of the liquid circulation rate. However, ionger residence times of the air bubbles and the higher mass transfer driving force that result at higher pressures improve oxygen utilization. The relationship between Tc and air load was independent of the operating pressure, provided the correlation is given as a function of the mean superficial air velocity. Neither liquid circulation nor gas holdup were significantly affected by liquid jet velocity. © 1995 John Wiley & Sons, Inc.
An experimental study on a β‐cyclodextrin carbonate membrane reactor in PNPA hydrolysis
Authors: Drioli Enrico , Natoli Mariapina , Koter Izabel , Trotta Francesco 
Published: December 2004

AbstractFlat sheet membranes made of polyetheretherketone, known as PEEK‐WC, and O‐octyloxycarbonyl β‐cyclodextrins were prepared by the phase inversion method. The cyclodextrins were entrapped in the polymeric membranes easily and simply in a single operation. Such functionalized membranes were tested for their catalytic activity. PNPA hydrolysis in a cyclodextrin membrane reactor was carried out as a model reaction. A significant improvement of reaction rate in comparison with the batch hydroxide ions catalyzed reaction was observed. © 1995 John Wiley & Sons, Inc.
A mathematical model for the growth of mycelial pellet populations
Authors: Tough A. J. , Pulham J. , Prosser J. I. 
Published: December 2004

AbstractIn liquid culture, filamentous organisms often grow in the form of pellets. Growth result in an increase in radius, whereas shear forces result in release of hyphal fragments which act as centers for further pellet growth and development. A previously published model for pellet growth of filamentous microorganisms has been examined and is found to be unstable for certain parameter values. This instability has been identified as being due to inaccuracies in estimating the numbers of fragments which seed the pellet population. A revised model has been formulated, based on similar premises, but adopting a finite element approach. This considers the population of pellets to be distributed in a range of size classes. Growth results in movement to classes of increasing pellet size, while fragments enter the smallest size class, from which they grow to form further pellets. The revised model is stable and predicts changes in the distribution of pellet sizes within a population growing in liquid batch culture. It considers pellet growth and death, with fragmentation providing new centers of growth within the pellet population, and predicts the effects of shear forces on pellet growth and size distribution. Predictions of pellet size distributions are tested using previously published data on the growth of fungal pellets and further predictions are generated which are suitable for experimental testing using cultures of filamentous fungi or actinomycetes. © 1995 John Wiley & Sons, Inc.
Polymerized liposome as ligand carrier for affinity precipitation of proteins
Authors: Sun Yan , Yu K. , Jin X. H. , Zhou X. Z. 
Published: December 2004

AbstractA polymerized liposome (PLS) was prepared using a synthesized phospholipid with a diacetylene moiety in the hydrophobic chain and an amino group in the hydrophilic head. The PLS was used as a novel ligand carrier for affinity precipitation of proteins because it showed a reversibly precipitable property on salt addition and removal. Soybean trypsin inhibitor (STI) was easily immobilized on the PLS by a one‐step carbodiimide reaction. The PLS showed no nonspecific adsoprtion of proteins. It had a large ligand coupling capacity, and then a large adsorption capacity for trypsin after STI immobilization. The PLS with immpbilized STI was recycled three times for the purification of trypsin from a crude pancreatic extract. Although the degree of purification was compromised by the impurity of the STI employed, in each run the purification factor reached about 6 and more than 80% of trypsin activity was recovered. The results indicated that the PLS was a potential ligand carrier for affinity precipitation of proteins. © 1995 John Wiley & Sons, Inc.
Thermal isoelectric precipitation of α‐lactalbumin from a whey protein concentrate: Influence of protein–calcium complexation
Authors: Bramaud C. , Aimar P. , Daufin G. 
Published: December 2004

AbstractThe selective precipitation of α‐lactalbumin (α‐LA) at a pH around its isoelectric point (4.2) under heat treatment is the basis for a fractionation process of whey proteins. As precipitation is a phenomenon dependent on the protein hydrophobicity, and as the release of the tightly bound calcium occurring at pH around 4 modifies the α‐LA hydrophobicity, the specific role of calcium on isoelectric precipitation is investigated. A study of the extent of α‐LA precipitation in a whey protein concentrate under various operating conditions of pH, temperature, protein concentration, and calcium content is presented. We propose a mechanism for this phenomenon as a combination of a complexation equilibrium and of an irreversible precipitation, to account for the influence of temperature, α‐LA concentration total ionic content, and calcium concentration, and also to estimate the complexation equilibrium constant. © 1995 John Wiley & Sons, Inc.
Influence of substrate oscillations on acetate formation and growth yield in Escherichia coli glucose limited fed‐batch cultivations
Authors: Neubauer P. , Häggström L. , Enfors S.‐O. 
Published: December 2004

AbstractA Large bioreactor is an inhomogenous system with concentration gradients which depend on the fluid dynamics and the mass transfer of the reactor, the feeding strategy, the saturation constant, and the cell density. The responses of Escherichia coli cells to short‐term oscillations of the carbon/energy substrate in glucose limited fed‐batch cultivations were studied in a two‐compartment reactor system consisting of a stirred tank reactor (STR) and an aerated plug flow reactor (PFR) as a recycle loop. Short‐term glucose excess or starvation in the PFR was simulated by feeding of glucose to the PFR or to the STR alternatively. The cellular response to repeated short‐term glucose excess was a transient increase of glucose consumption and acetate formation. But, there was no accumulation of acetate in the culture, because it was consumed in the STR part where the glucose concentration was growth limiting. However, acetate accumulated during the cultivation if the oxygen supply in the PFR was insufficient, causing higher acetate formation. The biomass yield was then negatively influenced, which was also the case if the PFR was used to simulate a glucose starvation zone. The results suggest that short‐term heterogeneities influence the cellular physiology and growth, and can be of major importance for the process performance. © 1995 John Wiley & Sons, Inc.
On‐line state recognition in a yeast fed‐batch culture using error vectors
Authors: Shimizu Hiroshi , Miura Keigo , Shioya Suteaki , Suga Ken‐ichi 
Published: December 2004

AbstractThe physiological states with respect to cell growth and ethanol production in a yeast fed‐batch culture expressed in linguistic form could be recognized on‐line by fuzzy inferencing based on error vectors. The error vector was newly defined here in a macroscopic elemental balance equation. The physiological states for cell growth and ethanol production were characterized by error vectors using many experimental data from fed‐batch cultures. Fuzzy membership functions were constructed from the frequency distributions of the error vectors and state recognition was performed by fuzzy inferencing. In particular, an unusual physiological state for a yeast cultivation, in which aerobic ethanol production was accompanied by very low cell growth, could be recognized accurately. According to the results of the state recognition, an energy parameter, the P/O ratio in the metabolic reaction model was adaptively estimated, and the cell growth was successfully evaluated with the estimated P/O. © 1995 John Wiley & Sons, Inc.
Cometabolic degradation of trichloroethylene in a bubble column bioscrubber
Authors: Hecht V. , Brebbermann D. , Bremer P. , Deckwer W.‐D 
Published: December 2004

AbstractA bubble column bioreactor was used as bioscrubber to carry out a feasibility study for the cometabolic degradation of trichloroethylene (TCE). Phenol was used as cosubstrate and inducer. The bioreactor was operated like a conventional chemostat with regard to the cosubstrate and low dilution rates were used to minimize the liquid outflow. TCE degradation measurements were carried out using superficial gas velocities between 0.47and 4.07 cm s−1 and TCE gas phase loads between 0.07 and 0.40 mg L−1 Depending on the superficial gas velocity used, degrees of conversion between 30% and 80% were obtained. A simplified reactor model using plug flow for the gas phase, mixed flow for the liquid phase, and pseudo first order reaction kinetics for the conversionof TCE was established. The model is able to give a reasonable approximation of the experimental data. TCE degradation at the used experimental conditions is mainly limited by reaction rate rather than by mass transfer rate. The model can be used to calculate the reactor volume and the biomass concentration for a required conversion. © 1995 John Wiley & Sons Inc.
Fed‐batch feeding and induction policies that improve foreign protein synthesis and stability by avoiding stress responses
Authors: Ramírez Delia M. , Bentley William E. 
Published: December 2004

AbstractIn this work, feeding policies aimed to avoid cellular stress responses as indicated by an increase in ATP‐dependent proteolysis are tested. A set of experiments was carried out where glucose, IPTG (inducer), and phenylalanine (rate‐limiting precursor) were added gradually in a fed‐batch fashion. A significant increase in CAT activity was found compared with pulse‐induction. In addition, there was a substantial increase in the rate of CAT synthesis as well as in the final specific CAT activity when phenylatanine and the inducer were added simultaneously. CAT degradation was confirmed through Western blotting analysis. Protease analysis (SDS‐GPAGE) indicated lower proteolytic activity for the IPTG and phenylalanine fed‐batch cases. GroEL immunoas‐says indicated that amplification of stress proteins occurred upon CAT induction. This research impacts the yield of soluble cytoplasmic proteins in Escherichia coli and suggests that metabolically based induction/feeding policies are beneficial. © 1995 John Wiley & Sons Inc.
Immobilization of fungal spores by adhesion
Authors: Gerin P. , Bellon‐Fontaine M. N. , Asther M. , Rouxhet P. G. 
Published: December 2004

AbstractImmobilization of conidiospores of Phanerochaete chrysosporium by adhesion was investigated in static and flow conditions on flat and on porous supports. Reducing the electrostatic repulsion between the spores and the support by adsorption of polycations on the support allows a better adhesion efficiency and a higher density of adhering spores and does not affect germination and growth. Formation of spore aggregates either in the suspension (high ionic strength) or on the support tends to decrease the surface coverage and to give an inhomogeneous distribution of adhering spores due to detachment of aggregates. The density of spores adhering from a flowing suspension is lower as compared with static conditions and does not exceed about 2% of surface coverage; this is due to the influence of tangential forces, to the short contact time with the surface, and to perturbation of the hydrodynamics along the surface by the previously immobilized spores. Obtaining a high coverage of the support by immobilized spores requires the absence of a tangential motion. © 1995 John Wiley & Sons, Inc.
Gas phase composition effects on suspension cultures of Taxus cuspidata
Authors: Mirjalili Noushin , Linden James C. 
Published: December 2004

AbstractThe effect of different concentrations and combinations of oxygen, carbon dioxide, and ethylene on cell growth and taxol production in suspension cultures of Taxus cuspidata was investigated using several factorial design experiments. Low head space oxygen concentration (10% v/v) promoted early production oftaxol. High carbon dioxide concentration (10% v/v) inhibited taxol production. The most effective gas mixture composition in terms of taxol production was 10% (v/v) oxygen, 0.5% (v/v) carbon dioxide, and 5 ppm ethylene. Cultures grown underambient concentration of oxygen had a delayed uptake of glucose and fructose compared to cultures grown under 10% (v/v) oxygen. Average calcium uptake rates into the cultured cells decreased and average phosphate uptake rates increased as ethylene was increased from 0 to 10 ppm. These results may indicate that gas composition alters partitioning of nutrients, which in turn affects secondary metabolite production. © 1995 John Wiley & Sons, Inc.
Enzymatic preparation of biosurfactants from sugars or sugar alcohols and fatty acids in organic media under reduced pressure
Authors: Ducret Amélie , Giroux André , Trani Michael , Lortie Robert 
Published: December 2004

AbstractBiosurfactants were prepared by enzymatic esterification of sugars and sugar alcohols in nonaqueous media. Sorbitol monooleate was produced in pure molten substrates, with reduced pressure to remove water. The results were compared to synthesis in organic solvent, with and without water removal. Synthesis in organic solvent with water removal, obtained by refluxing through a desiccant under reduced pressure, proved to be the most efficient method in terms of total yield and side‐products formation. This process was applied to the production of different surfactants, by changing the nature of the hydrophilic and hydrophobic moieties. Yields above 90% of monoesters were obtained after 24 h when the reaction was carried out in 2‐methyl‐2‐butanol with Novozym 435 (Type B lipase from Candida antarctica) with an excess of hydroxyl donor. © 1995 John Wiley & Sons, Inc.
A metabolic model of the biological phosphorus removal process: II. Validation during start‐up conditions
Authors: Smolders G. J. F. , Bulstra D. J. , Jacobs R. , van Loosdrecht M. C. M. , Heijnen J. J. 
Published: December 2004

AbstractA metabolic model of the biological phosphorus removal process has been developed and validated previously for complex conversions during the process under anaerobic and aerobic conditions at different growth rates in sequencing batch reactors in steady state. For additional validation of the metabolic model, the model was applied to the dynamic conditions which occur during the start‐up phase of the biological P removal in the presence and absence of non‐polyP heterotrophic microorganisms. In a laboratory scale sequencing batch reactor, experiments were performed to examine the enrichment of the population with polyphosphate organisms during the start‐up and the subsequent shift from non‐polyP, heterotrophic organisms to polyP organisms in the sludge. The effect of different influent loading patterns for acetate and phosphate was studied. In these experiments, the maximal growth rate of the polyP organisms and the behavior of the internal storage compounds could be derived. The metabolic model was capable of describing the experimental results, without the need to adjust the kinetic or stoichiometric parameters obtained under steady state conditions. © 1995 John Wiley & Sons, Inc.
Hydrodynamic, physiological, and morphological characteristics of Fusarium moniliforme in geometrically dissimilar stirred bioreactors
Authors: Priede M. A. , Vanags J. J. , Viesturs U. E. , Tucker K. G. , Bujalski W. , Thomas C. R. 
Published: December 2004

AbstractThe influence of two mixing geometries (at the same scale) with different flow energy distributions on the performance of the gibberellic acid fermentation and on the morphology of the producing fungus Fusarium moniliforme was investigated. Fermentations were performed using a turbine mixing system (TMS) and a counterflow mixing system (CMS), which were high and low power number mixing systems, respectively. Different agitator speed rate profiles were maintained to obtain equal specific power inputs to both mixing systems. Substantial differences in morphology and productivity of F. moniliforme were found. To investigate the causes of these differences, local values and spectra of the kinetic energy of flow fluctuations were measured during the fermentations using a stirring intensity measuring device (SIMD) and a frequency spectrum analyzer. Biomass and gibberellic acid concentrations were found to be higher in the TMS, where the energy distribution was less even, and Vi/here the main part of the energy was at small frequencies (large eddies). An automated image analysis method was used for quantitative characterization of F. moniliforme freely dispersed mycelia and clump morphology. A higher proportion of clumped mycelia with clumps of larger area, perimeter, and roughness was observed in the TMS. A correlation between the morphology and productivity was found, and TMS favored the development of more productive mycelia with longer and thinner hyphae. Introduced power was not a good parameter to characterize different impellers, even at a given scale. © 1995 John Wiley & Sons, Inc.
Glutamate modulates sodium‐potassium‐ATPase through cyclic GMP and cyclic GMP‐dependent protein kinase in rat striatum
Authors: Munhoz Carolina Demarchi , Kawamoto Elisa Mitiko , de Sá Lima Larissa , Lepsch Lucilia Brochado , Glezer Isaias , Marcourakis Tania , Scavone Cristoforo 
Published: December 2004

AbstractExcessive excitatory action of glutamate and nitric oxide (NO) has been implicated in degeneration of striatal neurons. Evidence had been provided that Na+K+‐ATPase might be involved in this process. Here we investigated whether glutamate‐regulated messengers, such as NO and cyclic GMP, could modulate the activity of membrane Na+K+‐ATPase. Our results demonstrated that NO donors sodium nitroprusside (SNP at 30 and 300 μM) and S‐nitroso‐N‐acetylpenicillamine (SNAP at 200 μM) increased α2,3Na+K+‐ATPase activity which was blocked by the NO chelator, haemoglobin and was independent of [Na+]. This regulation was associated with cGMP synthesis and mimicked by glutamate (300 μM) and 8‐Br‐cyclic GMP (4 mM). 8‐Br‐cGMP‐induced stimulation of Na+K+‐ATPase activity could be blocked by KT5823 (an inhibitor of cGMP‐dependent protein kinase, PKG), but not by KT5720 (an inhibitor of cAMP‐dependent protein kinase, PKA). N‐Methyl‐D‐aspartate (NMDA) receptors appeared to be involved in the effect of glutamate, since MK‐801 (NMDA receptor antagonist) produced a partial reduction in glutamate‐induced activation of the enzyme. MK‐801 was not synergistic to L‐NAME (NOS inhibitor), suggesting that glutamate stimulates the NMDA‐NOS pathway to activate α2,3 Na+K+‐ATPase in rat striatum. This regulation was associated with cyclic GMP (but not cyclic AMP) synthesis. These data indicate the existence, in vitro, of a regulatory pathway by which glutamate, acting through NO and cGMP, can cause alterations in striatal α2,3 Na+K+‐ATPase activity. Copyright © 2004 John Wiley & Sons, Ltd.
Role of DNA Sequence in the Binding Specificity of Synthetic Basic‐Helix‐Loop‐Helix Domains
Authors: Beltran Amy C. , Dawson Philip E. , Gottesfeld Joel M. 
Published: December 2004

AbstractThe basic helix‐loop‐helix (bHLH) domain defines a class of transcription factors that are essential for the regulation of many genes involved in cell differentiation and development. To determine the role of the DNA sequence in driving dimerization specificity of bHLH transcription factors, we analyzed the DNA sequence in and around a consensus hexanucleotide binding site (E‐box). The bHLH domains of two transcription factors, E12 and TAL1, were chemically synthesized. The minimal DNA binding domain for both the E12 homodimer and the E12–TAL1 heterodimer was determined, thereby extending the E‐box by two base pairs. Additional studies indicate that the presence of a thymine in the first flanking position 5′ to the E‐box prevents DNA binding of both dimer complexes. The presence of a thymine or cytosine in a flanking position two bases 5′ to the E‐box decreases the affinity for the E12 homodimer twofold but completely inactivates DNA binding for the E12–TAL1 heterodimer. Access to synthetic DNA and protein enabled the analysis of specific interactions between a conserved arginine residue in the basic helix of each bHLH domain and adenine in a flanking position two bases 5′ to the E‐box. Our results indicate a key role of the DNA sequence in driving dimerization specificity among bHLH transcription factors.