bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strategies for the Recovery of Chemicals from Fermentation: A Review of the Use of Polymeric Adsorbents
Authors: Garcia Antonio A. 
Published: March 2005

AbstractMany different compounds can be produced by using microorganisms or enzymes. An important element in the design of a viable biotechnological process is the selection of an economical and efficient separations train. Production of chemicals via biotechnology generally requires isolation and purification from dilute, aqueous solution. A general framework for separation process design relies on exploiting a unique molecular physicochemical property (or properties) for separating the molecule of interest from water and the other species in solution. Important properties that can be utilized for the recovery of low molecular weight polar compounds are molecular charge, hydrophobicity, Lewis acidity or basicity, volatility, and limited solubility. In turn, it can be useful to characterize molecular properties by using separation processes, such as, for example, hydrophobicity by measuring octanol/water partition coefficients. This paper reviews the use of adsorption onto hydrophobic, nonpolar macroreticular polymers and Lewis acid‐base complexation by using functionalized polymers for the recovery of amino acids, carboxylic acids, alcohols, and ketones from dilute aqueous solution. The focus will be on utilizing physical and chemical properties to predict uptake capacity. This information will be relevant to separation process development and will help to characterize molecular properties in aqueous solution.
Application of Population Balance Model to the Loss of Hybridoma Antibody Productivity
Authors: Lee Gyun Min , Varma Amit , Palsson Bernhard O. 
Published: March 2005

AbstractA simple dynamic model has been applied to explain the population dynamics of monoclonal antibody (MAb) producing (producer) and nonproducing hybridoma cells (nonproducer) coexisting in culture. The events of mutation or loss of genes associated with antibody synthesis have been incorporated into the model to account for the conversion of a producer to a nonproducer. The model shows that the cell population is not necessarily dominated by the nonproducer, and a steady balance of producer and nonproducer populations can be achieved. A nonproducer population is undesirable, and cultivation strategies to maximize MAb production are suggested, taking into account the dynamics of a nonproducer population.
Acetone‐Butanol‐Ethanol (ABE) Fermentation and Simultaneous Separation in a Trickle Bed Reactor
Authors: Park Chang‐Ho , Okos Martin R. , Wankat Phillip C. 
Published: March 2005

AbstractA new in situ product separation technique using gas stripping was applied to acetone‐butanol‐ethanol (ABE) fermentation in a gas‐phase‐continuous immobilized cell trickle bed reactor. Both numerical and experimental studies showed that glucose conversion could be improved when the inhibitory compounds were stripped by fermentation gas. Solvents were stripped preferentially from the fermentation broth, and butanol removal was as efficient as acetone removal in spite of butanol's high boiling point (117°C) because of butanol's high volatility at fermentation concentrations. Since most of the butanol was removed by gas stripping, organic acids played major roles among inhibitory products. Numerical analysis indicated that improvement of glucose conversion by gas stripping was more pronounced at higher gas flow rates, with stronger inhibition kinetics, and under vacuum conditions. Numerical calculation predicted that glucose concentrations higher than 60 g/L could be converted, but this could not be shown experimentally because of increased degeneration.
Metabolic Regulation of End Product Distribution in Lactobacilli: Causes and Consequences
Authors: Tseng Ching‐Ping , Montville Thomas J. 
Published: March 2005

AbstractThis review examines the regulation of end product distribution in Lactobacillus plantarum and other lactobacilli, the factors that influence this distribution, and the bioenergetic consequences of end product distribution. Similarities to and differences from other genera in the lactic acid bacteria are described. Lactobacilli use many different transport systems to obtain nutrients. Carbohydrates and organic acids are transported in cells by specific phosphoenolpyruvate phosphotransferases (PEP—PTS) or permeases. The carbohydrates are then metabolized to different end products through a common key intermediate, pyruvate. The ability of lactobacilli to produce various end products depends on species, strains, genetic capacity, expression of enzyme activity, sugar structure, and environmental conditions. The regeneration of the NAD+ required for continued glycolysis is a key regulatory factor of end product distribution. The excretion of protons with acidic end products can directly generate a proton motive force and it also contributes to intracellular pH homeostasis. Anionic precursor—product exchange systems can also generate a proton motive force if the exchange is not electroneutral.
Characterization of Gene Expression in Recombinant Escherichia coli Cells Infected with Phage λ
Authors: Miao Fudu , Drake Steven K. , Kompala Dhinakar S. 
Published: March 2005

AbstractPhage λ infection was investigated for possible production of toxic foreign proteins in Escherichia coli. The target gene transcription was regulated by a T7 promoter, which was initiated under the action of T7 RNA polymerase delivered by infecting phage. Two types of phage infection were investigated. In both cases, deletion of the int gene prevents lysogenic integration. One phage, λCE6, contains the Sam7 lysis mutation, so that infectious phage particles remain intracellular. The other phage, λCE6M, undergoes the complete lytic pathway so that the infected cell is eventually lysed. The dynamics of phage adsorption, foreign protein synthesis, and cell growth were analyzed as a function of various parameters, such as MOI (multiplicity of infection), cell concentration at infection, culture temperature, and different carbon sources. A low basal level of the foreign protein, β‐galactosidase, was obtained prior to infection, whereas it reached about 0.1 g/L after phage “induction” under appropriate infection conditions. Due to low basal expression, this expression system is useful for the production of toxic foreign proteins.
Large‐Scale Production of κ‐Carrageenan Droplets for Gel‐Bead Production: Theoretical and Practical Limitations of Size and Production Rate
Authors: Hunik Jan H. , Tramper Johannes 
Published: March 2005

AbstractImmobilization of biocatalysts in κ‐carrageenan gel beads is a widely used technique nowadays. Several methods are used to produce the gel beads. The gel‐bead production rate is usually sufficient to make the relatively small quantities needed for bench‐scale experiments. The droplet diameter can, within limits, be adjusted to the desired size, but it is difficult to predict because of the non‐Newtonian fluid behavior of the κ‐carrageenan solution. Here we present the further scale‐up of the extrusion technique with the theory to predict the droplet diameters for non‐Newtonian fluids. The emphasis is on the droplet formation, which is the rate‐limiting step in this extrusion technique. Uniform droplets were formed by breaking up a capillary jet with a sinusoidal signal of a vibration exciter. At the maximum production rate of 27.6 dm3/h, uniform droplets with a diameter of (2.1 ± 0.12) × 10−3 m were obtained. This maximum flow rate was limited by the power transfer of the vibration exciter to the liquid flow. It was possible to get a good prediction of the droplet diameter by estimating the local viscosity from shear‐rate calculations and an experimental relation between the shear rate and viscosity. In this way the theory of Newtonian fluids could be used for the non‐Newtonian κ‐carrageenan solution. The calculated optimal break‐up frequencies and droplet sizes were in good agreement with those found in the experiments.
Ion Exchange of Lysozyme during Permeation across a Microporous Sulfopropyl‐Group‐Containing Hollow Fiber
Authors: Shinano Hironori , Tsuneda Satoshi , Saito Kyoichi , Furusaki Shintaro , Sugo Takanobu 
Published: March 2005

AbstractA microporous hollow fiber containing a sulfopropyl (SP) group as a strongly acidic cation‐exchange group was prepared by radiation‐induced graft polymerization of glycidyl methacrylate, followed by hydrolysis of the resulting epoxide group into a diol, and then conversion of the diol into the SP group. The SP group density of the resulting hollow fiber ranged from 0.21 to 0.84 mol/kg of dry fiber with a pure water flux of 2.7 m/h at a filtration pressure of 0.1 MPa. Lysozyme adsorption was examined during permeation of the lysozyme solution (pH 6) through the pores across a microporous cation‐exchange hollow fiber. The lysozyme concentration of the effluent penetrating the outside of the hollow fiber did not change irrespective of the residence time of the solution across the hollow fiber, which was indicative of the negligible diffusional resistance of lysozyme to the SP group. The binding capacity of lysozyme to the fiber was constant in this range of SP group density. For comparison, the adsorption characteristics of a cupric chloride solution during permeation were also determined. The binding capacity of Cu to the fiber increased linearly with increasing SP group density, because cupric ions of a smaller size than lysozyme can invade the depths of the grafted polymer branches formed in the amorphous domain of the polymer matrix.
Affinity‐Based Reverse Micellar Extraction and Separation (ARMES): A Facile Technique for the Purification of Peroxidase from Soybean Hulls
Authors: Paradkar Vikram M. , Dordick Jonathan S. 
Published: March 2005

AbstractA new technique for the purification of proteins has been developed which combines the high selectivity of affinity interaction with the scalability and ease of operation of liquid‐liquid extraction. The approach is called affinity‐based reverse micellar extraction and separation (ARMES). The salient features of ARMES include the following: (1) intraphasic interaction between the ligand and ligate which provides for high ligand utilization; (2) no chemical modification of the ligand is needed; and (3) ease of operation and inherent scalability due to the use of liquid‐liquid extraction. This technique has been used to purify the peroxidase from soybean hulls using the lectin concanavalin A (con A) as a sugar‐binding affinity ligand. A purification factor of 30 is achieved to provide a nearly pure peroxidase solution (as determined by HPLC and SDS‐PAGE) with nearly complete regeneration of the con A ligand. We propose that ARMES will be useful in the facile purification of complex biomolecules such as glycoform protein variants using lectins as affinity ligands and proteins of therapeutic importance using antibodies as affinity ligands.
Expansion and Differentiation of Human Hematopoietic Cells from Static Cultures through Small‐Scale Bioreactors
Authors: Sardonini Charles A. , Wu Ying‐Jye 
Published: March 2005

AbstractMaintenance of the progenitor cells responsible for hematopoiesis has generally been accomplished using a feeder layer of stromal cells in stationary culture. Here, we compared the expansion of the total cell and progenitor cell populations using low‐density mononuclear cells (LDMCs) obtained from human bone marrow in static culture (T‐flasks) and in different cell culture bioreactors designed for the scale‐up of mammalian cells. Static cultures were performed without the presence of a previously established stromal cell layer. Expansion of marrow in all cases was accomplished through the use of added cytokines such as IL‐3, GM‐CSF, and c‐kit ligand. The results for the total cell expansion in static culture ranged from 4.4‐ to 32‐fold. The cell number increase was affected by such factors as patient to patient variability, freeze‐thawing, and the combination of cytokines used. Due to widespread use and the small amount of marrow needed, static cultures were used as a basis for comparison with other expansion systems. The cell culture systems used to evaluate the scale‐up of marrow cultures included suspension, microcarrier, airlift, and hollow fiber bioreactors. Using identical media, cytokines, and feed schedules, LDMCs in the suspension bioreactor expanded to a value of 1.6 compared to a normalized value of 1.0 for static cultures for the two runs investigated. Expansion results for microcarrier cultures averaged 0.75 when compared to static cultures. A cell number increase in the airlift bioreactor resulted in an expansion which was 0.70 of the control static culture. Granulocyte—macrophage and erythroid progenitor assay data were also evaluated for the suspension, microcarrier, and airlift bioreactors. A single run for the hollow fiber system demonstrated no observable expansion of hematopoietic cells when compared to control static cultures. However, this finding may be a reflection of the inefficiency in retrieving cells from the extracapillary space of the hollow fiber bioreactor. Although the expansion results observed here are of limited clinical utility, these studies provide a basis for future development for the scale‐up of hematopoietic cultures.
Colloidal Properties of Flocculent and Nonflocculent Brewing Yeast Suspensions
Authors: Speers R. Alex , Durance Timothy D. , Tung Marvin A. , Tou Janet 
Published: March 2005

AbstractThe orthokinetic flocculation rates of four suspensions of Saccharomyces cerevisiae and Saccharomyces uvarum (calsbergensis) were measured using steady shear rheometry and light microscopy. These results, along with cell ζ potential values previously reported by the authors, allowed us to test the applicability of DLVO (Derjaguin, Landau, Verwey, and Overbeek) mediated orthokinetic flocculation models. The findings also permitted examination of the validity of the elastic floe model and allowed estimation of the force required to separate cell doublets. Cellular suspensions of brewing yeast were subjected to a high shear treatment to reduce any floes to single cells. Periodic samples were then taken while shearing the suspension at 200 s−1, and the extent of flocculation was determined via light microscopy. The logarithm of floe concentration was linearly dependent on shearing time. It was possible to estimate orthokinetic capture coefficients (αo) for the four strains, with values ranging from 0.00025 to 0.0010. By using measured and “typical” colloidal parameters, a theoretical αo value was derived which was much lower than the experimental values (i. e., αot ≪ 0.0001). Thus, it was concluded that the DLVO flocculation model could not be used to explain brewing yeast flocculation. Flow behavior of the yeast suspensions followed the Bingham model above a critical shear rate. Values of this critical shear rate (which predicts the point at which cell doublets separate) were used to calculate the force required to separate doublet cells. A calculated force of 2.2 × 10−11 N was similar to that of lectin‐like bonds that are believed to be involved in yeast flocculation. As well, the elastic floe model could be employed to predict Bingham yield stress values.
Molecular Cloning of the γ‐Glutamyltranspeptidase Gene from a Pseudomonas Strain
Authors: Ishiye Masayuki , Yamashita Mitsuo , Niwa Mineo 
Published: March 2005

Abstractγ‐Glutamyltranspeptidase (GGT) was purified from a Pseudomonas sp. strain A14. The purified enzyme was found to be composed of two nonidentical subunits with molecular weights of 39000 and 22000 and had a pI of >8.6. The partial N‐terminal amino acid sequences of both subunits and some proteolytic fragments were determined. Using mixed oligonucleotides designed from the partial amino acid sequences as hybridization probes, one cosmid clone which contained the GGT gene was isolated from a Pseudomonas sp. strain A14 cosmid genome library, and the DNA sequence of the GGT gene was determined. The nucleotide sequence and the protein sequence analysis revealed that GGT was synthesized as a precursor protein of 575 amino acids and then processed to mature enzyme, presumably after removal of a signal peptide. Comparison of the predicted amino acid sequence of Pseudomonas GGT with published results for Escherichia coli K‐12 and rat kidney GGTs shows that the protein sequence of Pseudomonas GGT is 51% and 33% identical to the E. coli and rat GGT sequences, respectively. Higher similarity is observed among the small subunits, which have been thought to have a binding site for the γ‐glutamyl residue. Expression of the cloned Pseudomonas GGT gene in E. coli was subjected to Western blot analysis using antibody raised against the purified GGT. This suggested that processing of the precursor protein to its subunits is temperature‐dependent, because the amount of mature GGT protein was increased when the culture was performed at low temperature.
Sub‐Micrometer‐Sized Biodegradable Particles of Poly(L‐Lactic Acid) via the Gas Antisolvent Spray Precipitation Process
Authors: Randolph Theodore W. , Randolph Alan D. , Mebes Michael , Yeung Sharon 
Published: March 2005

AbstractSub‐micrometer‐sized particles of poly(L‐lactic acid) may be formed by using nearcritical or supercritical carbon dioxide as an antisolvent to precipitate poly(L‐lactic acid) from droplets of methylene chloride solution sprayed into a carbon dioxide continuous phase. Particle sizes may be controlled by varying the density of the carbon dioxide; at constant temperature in the supercritical region, higher carbon dioxide densities yield larger particles. Two methods (one batch and one continuous) for introducing the poly(L‐lactic acid) solutions into carbon dioxide are demonstrated. Although the two methods use very different mechanisms for forming the droplets, similar particle sizes are observed as a function of carbon dioxide density. We suggest that mass transport, rather than jet breakup and hydrodynamics, controls particle sizes in the near‐critical and supercritical regions.
Effect of Preinduction Specific Growth Rate on Secretion of Granulocyte Macrophage Colony Stimulating Factor by Escherichia coli
Authors: Curless Craig E. , Pope Joe , Loredo Lawrence , Tsai Larry B. 
Published: March 2005

AbstractThe effect of preinduction specific growth rate on the rate of synthesis and processing of granulocyte macrophage colony stimulating factor (GMCSF) secreted by Escherichia coli was investigated. A chemostat was used to explore preinduction growth rates ranging from 0.038 to 0.2/h. The maximum yields of both total GMCSF and processed GMCSF were found to occur at a preinduction growth rate of 0.13h. It was also discovered that if the postinduction feed rate is reduced at a preinduction growth rate near 0.13h, then the same amount of processed GMCSF is formed, but no unprocessed GMCSF is produced. It was hypothesized that the rate of synthesis of total GMCSF increases with an increased preinduction specific growth rate, but translocation across the cytoplasmic membrane and processing is rate‐limiting. Increased degradation of GMCSF during induction at higher preinduction specific growth rates decreased the amount of GMCSF produced.
Sevoflurane versus Halothane: Postoperative Maladaptive Behavioral Changes
Authors: Kain Zeev N. , Caldwell-Andrews Alison A. , Weinberg Megan E. , Mayes Linda C. , Wang Shu-Ming , Gaal Dorothy , Saadat Haleh , Maranets Inna 
Published: March 2005

Background
The authors conducted a double-blind, randomized, controlled trial to determine whether the use of sevoflurane in children undergoing anesthesia and surgery results in a higher incidence of postoperative maladaptive behavioral changes as compared with halothane.

Methods
Children and their parents (n = 102) were randomly assigned to either a halothane group (n = 50) or a sevoflurane group (n = 52). The intraoperative anesthetic protocol was strictly controlled, and the postoperative analgesic consumption and pain levels were recorded. The effect of the group assignment on emergence status and maladaptive postoperative behavioral changes was assessed both by validated psychological measures and physiologic instruments (actigraphy) on postoperative days 1-7. Anxiety of the parent and child was also assessed, as was the child's postoperative recovery (Recovery Inventory).

Results
There were no group differences in preoperative state anxiety, postoperative analgesic requirements, postoperative pain, or the incidence of emergence delirium (P = not significant). Two-way repeated-measures analysis of variance showed no group differences in the incidence of postoperative maladaptive behaviors (F4,72 = 0.60, P = 0.701) or actigraphic variables such as percent sleep, number of night awakenings, and night awakenings that lasted for more than 5 min (P = not significant).

Conclusion
The authors found no increased incidence of emergence delirium, maladaptive postoperative behavior changes, or sleep disturbances in children undergoing anesthesia with sevoflurane as compared with halothane.
Tranexamic Acid Reduces Intraoperative Blood Loss in Pediatric Patients Undergoing Scoliosis Surgery
Authors: Sethna Navil F. , Zurakowski David , Brustowicz Robert M. , Bacsik Julianne , Sullivan Lorna J. , Shapiro Frederic 
Published: March 2005

Background
Excessive bleeding often occurs during pediatric scoliosis surgery and is attributed to numerous factors, including accelerated fibrinolysis. The authors hypothesized that administration of tranexamic acid would reduce bleeding and transfusion requirements during scoliosis surgery.

Methods
Forty-four patients scheduled to undergo elective spinal fusion were randomly assigned to receive either 100 mg/kg tranexamic acid before incision followed by an infusion of 10 mg . kg . h during surgery (tranexamic acid group) or 0.9% saline (placebo group). General anesthesia was administered according to a standard protocol. Blood loss, transfusion requirements, coagulation parameters, and complications were assessed.

Results
In the tranexamic acid group, blood loss was reduced by 41% compared with placebo (1,230 +/- 535 vs. 2,085 +/- 1,188 ml; P < 0.01). The amount of blood transfused did not differ between groups (615 +/- 460 vs. 940 +/- 718 ml; P = 0.08). Administration of tranexamic acid was a multivariate predictor of blood loss, as was American Society of Anesthesiologists physical status and preoperative platelet count. No apparent adverse drug effects occurred in any patient.

Conclusion
Intraoperative administration of tranexamic acid significantly reduces blood loss during spinal surgery in children with scoliosis.