bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pleural fluid interferon‐γ and adenosine deaminase levels in tuberculosis pleural effusion: a cost‐effectiveness analysis
Authors: Sharma S.K. , Banga Amit 
Published: March 2005

AbstractPleural fluid levels of interferon‐γ (IFN‐γ) and adenosine deaminase (ADA) have been found to be high in patients with tuberculosis (TB). The present study was carried out to compare the diagnostic utility of these two markers and to carry out a cost‐effectiveness analysis of performing IFN‐γ estimation in comparison to ADA. A total of 52 patients with pleural effusion, 35 of which were found to have TB etiology, were prospectively included for estimation of ADA and IFN‐γ levels. The difference in the cost of performing the two diagnostic tests was compared with the cost of the treatment for a patient with TB. Pleural fluid IFN‐γ (median [range]: 2,100 [70–14,000] vs. 3 [0–160]; P<0.001) as well as ADA levels (mean [SD]: 93.1 [62.3] vs 15.4 [8.7]; P<0.001) were significantly higher in patients with TB effusion. Even though IFN‐γ estimation was more sensitive (97.1 vs. 91.4%), the extra cost of IFN‐γ estimation for detecting one patient with TB was found to be equivalent to the cost of a complete course of antituberculosis treatment for six patients. In developing countries, where TB is rampant and cost is a major concern, pleural fluid IFN‐γ estimation does not seem to be a cost‐effective investigation method for differentiating TB from non‐TB pleural effusion. J. Clin. Lab. Anal. 19:40–46, 2005. © 2005 Wiley‐Liss, Inc.
Pericentric inversion of chromosome 2 and echogenic vasculature in the basal ganglia: A new finding?
Authors: Pezzati Marco , Giovannucci Maria Luisa Uzielli , Filippi Luca , Dani Carlo , Rubaltelli Firmino F. 
Published: March 2005

AbstractLinear branching echogenicities in the thalamus or basal ganglia have been reported in infants with several genetic and nongenetic disorders. In this article, we report 2 cases of newborns with a neurosonographic diagnosis of thalamic/basal ganglia vasculopathy and karyotype analysis showing pericentric inversion of chromosome 2. To our knowledge, there has been no previous mention of an association between these entities. © 2005 Wiley Periodicals, Inc. J Clin Ultrasound 33:146–148, 2005
Kinetic study of polypropylene nanocomposite thermo‐oxidative degradation
Authors: Lomakin Sergei M , Dubnikova Irina L , Berezina Svetlana M , Zaikov Gennadi E 
Published: March 2005

AbstractPolypropylene (PP) has wide acceptance for use in many application areas. However, low thermal resistance complicates its general practice. The new approach in thermal stabilization of PP is based on the synthesis of PP nanocomposites. This paper discusses new advances in the study of the thermo‐oxidative degradation of PP nanocomposite. The observed results are interpreted by a proposed kinetic model, and the predominant role of the one‐dimensional diffusion type reaction. According to the kinetic analysis, PP nanocomposites had superior thermal and fireproof behaviour compared with neat PP. Copyright © 2005 Society of Chemical Industry
Design and Control of a Process to Extract β‐Carotene with Supercritical Carbon Dioxide
Authors: Cygnarowicz Miriam L. , Seider Warren D. 
Published: March 2005

AbstractA strategy for locating optimal designs is applied to the extraction of β‐carotene with supercritical C02. With the modified Peng‐Robinson equation of state to estimate the phase equilibria, models are developed to simulate the three‐phase (solid, liquid, and supercritical fluid) extraction and separation processes. The design optimization minimizes the annualized cost while producing β‐carotene of the desired quality. The results demonstrate that despite high operating pressures, supercritical extraction can be competitive for the recovery of high‐value products at low production rates. Furthermore, the increases in solubility with small amounts of cosolvent can have a substantial impact on the economics of the proposed design. An example is given in which the addition of 1 % ethanol to the C02 solvent transforms an unfavorable design into a competitive one. In addition, a dynamic model is proposed for the product separator, and its differential‐algebraic equations are integrated with DASSL. Proportional (P) and proportional‐integral (PI) control schemes are studied to maintain the pressure by manipulating the vapor flow rate. Although the set‐point response of the PI controller is acceptable, disturbance rejection is poor. A disturbance in the feed flow rate causes lower quality β‐carotene to be produced. The desired quality is maintained when the separator is overdesigned, but this raises the annualized cost.
Multimolecular Process in a Packed‐Bed Immobilized Enzyme Reactor: Numerical Simulation and Back‐Mixing Effects
Authors: Guzy S. , Saidel G. M. , Lotan N. 
Published: March 2005

AbstractIn a previous report, we presented a new analytical model describing the performance of a packed‐bed catalytic unit, where the reaction between two cosubstrates is catalyzed by an enzyme immobilized on a porous carrier. The model explicitly takes into account the changes in concentrations of both cosubstrates along the reactor, as well as the hydrodynamic regimen (i.e., back‐mixing) prevailing in the packed bed. In the present report, and on the basis of the procedures developed, we present a detailed analysis of the performance of the reactor. With numerical simulations, the effects of internal diffusion limitations, the depth of the pores, the substrates' concentration in the feed, and kinetic parameters are evaluated. Particular attention is also given here to the back‐mixing effects prevailing in the reactor. An experimental procedure for assessing their extent is described.
A Method To Disperse Aggregates of a Flocculent Yeast for Photometric Analysis
Authors: Castellon‐Vogel Martha A. , Menawat Anil S. 
Published: March 2005

AbstractStrategies to disperse aggregates so the cells remain in suspension long enough to take stable absorbance readings are studied. The optical density of highly flocculating yeasts, such as Saccharomyces cerevisiae ATCC 26603, drops because of cells settling to the bottom in less than 1 min. It presents a problem in using turbidimetric measurement for cell density estimate. Dilution of the yeast samples with sodium salts in a wide range of concentrations (10 mM to 1 M) disperses the aggregates, whereas dilution with calcium salts does not. ζ‐Potential measurements indicate that sodium disperses the yeast flocs by reversal of the charges on the cell surfaces. An attempt is also made to resolve the controversy about the role of sodium ions in flocculation.
Practical Method for Estimating Oxygen Kinetic and Metabolic Parameters
Authors: Cho Moo H. , Wang Shaw S. 
Published: March 2005

AbstractA practical and simple method was developed to determine the oxygen kinetic and metabolic parameters of cell cultures. The said parameters are the oxygen kinetic constant (Ko2), the maximum specific oxygen uptake rate (qmax), the maximum oxygen yield (Y), the critical dissolved oxygen (DO) (Ccr), and the oxygen maintenance coefficient (mo2). These parameters can be calculated from the results of one batch fermentation run. The fermentation needs to be run at an oxygen‐limiting condition, and the profiles of DO and cell density need to be recorded. A demonstration of the use of this method was done by using a yeast, Kluyveromyces marxianus.
λ Vectors for Stable Cloned Gene Expression
Authors: Padukone N. , Peretti S. W. , Ollis D. F. 
Published: March 2005

AbstractThe bacteriophage λ offers a unique opportunity concurrently to minimize segregational instability in recombinant systems by chromosomal integration of the cloned gene and to achieve high cloned gene expression during an abortive lytic phase. Lysis leads approximately to a 100‐fold amplification of the cloned gene. Cell lysis in the lytic state is blocked by a specific mutation (Sam), allowing the cell to maintain its integrity, and λ DNA packaging is blocked by other mutations (Wam, Eam) that keep cloned genes open to transcription. In the presence of these mutations, extremely high levels of cloned β‐galactosidase (more than 15% of total cell protein) have been obtained during abortive lysis from vectors found to be essentially 100% stable for over 75 generations in the lysogenic phase.
Mathematical Modeling and Simulations of Membrane Bioreactor Extractive Fermentations
Authors: Steinmeyer D. E. , Shuler M. L. 
Published: March 2005

AbstractA model of extractive ethanol fermentation within a membrane bioreactor has been constructed by using a structured, nonsegregated model of Saccharomyces cerevisiae. The model has been tested by comparing actual and simulated reactor fermentations. The time‐dependent approach to steady‐state operation is well predicted. The model has also been used to examine an array of alternative operating strategies.
Characterization of the Swelling of a Size‐Exclusion Gel
Authors: Monke Karen , Velayudhan Ajoy , Ladisch Michael R. 
Published: March 2005

AbstractThe swelling of a dextran gel, Sephadex G‐75, was observed in an aqueous environment at room temperature by a noninvasive technique that uses light microscopy coupled to an image analysis system via a video camera. The rate of swelling was found to follow the Tanaka and Fillmore theory, from which the overall gel diffusion coefficient was estimated as 6.3 × 10−7 cm2/s. In addition to giving a quantitative measure of gel swelling that could be useful in the mechanical design of liquid chromatography columns, this approach provides data on wet particle size and particle size range, which is needed for the modeling of diffusional and mass transfer effects in size‐exclusion chromatography. In this context, key observations are that the gel particles are nearly spherical with an elliptical shape factor of 0.98 (perfect sphere=1) and that there is little difference between sizes of particles obtained in water, 50 mM Tris‐glycine buffer (pH 10.2), and buffer containing 1 mg/mL protein. The diameter of the dry material ranged from 20 to 100 μm, while the hydrated particles had diameters of 40–350 μm. The rate of swelling is rapid, with 50% swelling occurring in about 10 s and swelling to 99% of the final wet particle size being obtained in less than 90 s.
Feedback Regulation in Preparative Elution Chromatography
Authors: Frey Douglas D. 
Published: March 2005

AbstractInput‐output models utilizing discrete variables are developed for elution chromatography and used together with control theory to investigate behavior patterns between output variables (e.g., yield, purity, and production rate) and input variables (e.g., cut point locations and feed slug size). Variable interactions and controllability characteristics for isocratic and stepwise gradient elution in linear and nonlinear chromatography are investigated by using the relative gain array, singular value decomposition, and direct simulation. Inverse‐based regulatory systems are evaluated for updating process inputs by using information on process outputs such that product quality and system performance parameters are efficiently maintained for the case where the column is overloaded and the solute peaks overlap with each other. Strategies for feedback optimizing control are also discussed.
Growth, Metabolic, And Antibody Production Kinetics Of Hybridoma Cell Culture: 1. Analysis Of Data From Controlled Batch Reactors
Authors: Ozturk Sadettin S , Palsson Bernhard O 
Published: March 2005

AbstractA mouse‐mouse hybridoma cell line (167.4G5.3) was cultivated in a 1.5‐L stirred‐tank bioreactor under constant pH and dissolved oxygen concentration. The transient kinetics of cell growth, metabolism, and antibody production were followed by biochemical and flow cytometric methods. The cell‐specific kinetic parameters (growth and metabolic rates) as well as cell size were constant throughout the exponential phase. Intracellular protein and RNA content followed a similar trend. Cell growth stopped when the glutamine in the medium was depleted. Glucose could not substitute for glutamine, as glucose consumption ceased after glutamine depletion. Ammonia and lactate production followed closely glutamine and glucose consumption, respectively. Alanine, glutamate, serine, and glycine were produced but other amino acids were consumed. The cells are estimated to obtain about 45% of the total energy from glycolysis, with the balance of the metabolic energy provided by oxidative phosphorylation. The antibody was produced at a constant rate in both the exponential and decline phases of growth. The intracellular antibody content of the cells remained relatively constant during the exponential phase of growth and decreased slightly afterwards.
Kinetics of Peroxidase Production by Streptomyces viridosporus and Recombinant Streptomyces lividans
Authors: Korus Roger A , Lodha Sanjay J , Adhi Tri P , Crawford Don L. 
Published: March 2005

AbstractThe production of peroxidases by Streptomyces viridosporus T7A and recombinant Streptomyces lividans TK64.1 was characterized in stirred tank fermentors. The rate of peroxidase production was strongly growth associated with plasmid‐coded S. lividans, in contrast to chromosome‐coded S. viridosporus, where peroxidase production was proportional to cell mass rather than cell growth rate. A modified form of the logistic equation gave a good fit to the experimenal data for cell growth and peroxidase formation.
Model for Transient Moisture Profiles of a Drying Apple Slab Using the Data Obtained with Magnetic Resonance Imaging
Authors: Mccarthy Michael J , Perez Ernest , Özilgen Mustafa 
Published: March 2005

AbstractThe use of magnetic resonance imaging (MRI) spectroscopy as a real time probe to noninvasively obtain transient moisture profiles during food dehydration is demonstrated. A laboratory‐scale wind tunnel drier was constructed. A 2 × 5 × 5 cm3 apple slab was inserted in the probative zone and one‐dimensional drying was effected at quasiisothermal conditions. Spatial resolution of 0.60 mm was obtained. The transient moisture profiles were simulated with a simple mass transfer model. Effective diffusivity of water in the apple was calculated as 8.3 × 10−5 cm2/s.
Nonlinear Gradient Isotherm Parameter Estimation for Proteins with Consideration of Salt Competition and Multiple Forms
Authors: Whitley Roger D , Berninger James A , Rouhana Nathalie , Wang N.‐H Linda 
Published: March 2005

AbstractSalt gradients in ion‐exchange chromatography are routinely used to speed separation of proteins and to concentrate products, but systematic optimization of these gradients requires protein equilibrium data as a function of salt concentration. An understanding of conformational changes, aggregation, and salt effects, which include both competition and affinity modulation, is important for equilibrium isotherm parameter estimation. In this study, gradient elution of bovine serum albumin (BSA) in anion exchange was well predicted by a salt‐modulated nonlinear isotherm which considers salt competition. The isotherm was able to predict BSA gradient elution from batch equilibrium data. The same isotherm was also able to predict elution for various gradient slopes when fitted to an intermediate slope gradient experiment. If multiple forms due to aggregation or denaturation exist, isotherm parameters are readily averaged in batch experiments because of the long equilibration times. Similarly, gradient experiments yield averaged parameters because the salt gradient tends to merge the closely eluting forms. However, in isocractic elution, if the reaction rate is not rapid enough to give a merged peak, the estimated isotherm parameters are only fair predictors of gradient behavior and vice versa. Slower flow rates in isocratic elution can help reduce the discrepancy by allowing forms to merge through interconversion. As an alternative to determining averaged parameters, consideration of two binding forms, using VERSE‐LC, an advanced rate model, gave good agreement with experimental data over the entire range of salt gradient durations.
Effective Diffusivity of Galactose in Calcium Alginate Gels Containing Immobilized Zymomonas mobilis
Authors: Korgel Brian A. , Rotem Abraham , Monbouquette Harold G. 
Published: March 2005

AbstractThe effective diffusivity of galactose was measured for calcium alginate gel membranes containing immobilized live Zymomonas mobilis cells at concentrations ranging from 0 to 150 g dry wt/L of gel. Since galactose is not taken up by living Z. mobilis organisms, the diffusion of this representative six‐carbon sugar could be studied independently of sugar consumption. Various immobilized biomass loadings were achieved by two different techniques: addition of biomass at known concentrations to the sodium alginate solution before membrane formation and growth of cells in the gel to various biomass concentrations. The highest immobilized cell concentration, attained by in situ growth, corresponds to the maximum for this system, as growth beyond this maximum concentration led to disintegration of the gel membrane. The galactose effective diffusivity measurements for both methods of immobilized cell loading overlap within experimental error and follow the same general monotonic decline with entrapped biomass concentration. Most of the data fall below the upper bound predicted by Hashin and Shtrikman (1962) and show good agreement with the random pore model of Wakao and Smith (1962, 1964). Available effective diffusivity data from the literature provide evidence that the random pore model is an excellent predictor of sugar effective diffusivity in gel immobilized cell systems in general.
Enzymatic Regulation of Glucose Catabolism by Lactobacillus plantarum in an Aerobic Chemostat
Authors: Tseng Ching‐Ping , Montville Thomas J. 
Published: March 2005

AbstractThe influence of oxygen on the metabolic regulation of glucose catabolism by Lactobacillus plantarum 8014 was examined in a chemostat (D=0.2 h−1, pH 5.5). A steadystate anaerobic culture was shifted to an aerobic condition by imposing an oxygen transfer rate of 1.84 mmol L−1 min−1. Enzyme activities, end product concentrations, and ATP levels were determined during the resultant transition and under steady‐state aerobic conditions. During the transition, oxygen was consumed by the aerobic culture and the intracellular ATP concentration increased until hydrogen peroxide, which also increased, became inhibitory. Under the aerobic condition, the steady‐state specific rate of substrate utilization and acetate production increased. The lactate dehydrogenase, NAD‐dependent lactate dehydrogenase, acetate kinase, pyruvate oxidase, and NADH oxidase specific activities all increased under aerobic conditions. Changes in the intracellular lactate and acetate concentrations had a temporal correspondence with the changes in the aforementioned catabolic activities. Subsequent experiments using chloramphenicol to inhibit de novo protein synthesis and kinetic analysis of crude enzyme extracts suggested that these changes were due to both changes in synthesis and activity levels.
Micropatterning Proteins and Synthetic Peptides on Solid Supports: A Novel Application for Microelectronics Fabrication Technology
Authors: Britland Stephen , Perez‐Arnaud Enrique , Clark Peter , McGinn Brian , Connolly Patricia , Moores Geoffrey 
Published: March 2005

AbstractIn this paper, we describe a method for immobilizing proteins and synthesizing peptides in micrometer‐dimension patterns on solid supports. Microelectronics fabrication technology was adapted and used to lithographically direct the location of immobilization of proteins on appropriately derivatized surfaces. As examples, we micropatterned the protein bovine serum albumin (BSA) and the enzyme horseradish peroxidase (HRP). The catalytic activity of HRP was shown to be retained after being cross‐linked to the support. When coupled with solid‐phase peptide synthesis, the technique allowed synthetic peptides to be constructed in patterns again having micrometer dimensions. Synthetic polypeptides, polylysine, were constructed in patterns with dimensions that approached the practical limit of resolution for optical lithography at 1–2 μman. The patterns of immobilized molecules and synthetic peptides were visualized using histochemical methods together with light and fluorescence microscopy. The protein and peptide patterning technique described here is an advance in the field of bioelectronics. In particular, it should now be possible to devise novel methods for interfacing with biological systems and constructing new devices for incorporation into miniaturized biosensors.
Spin Labeling and Kinetic Studies of a Membrane‐Immobilized Proteolytic Enzyme
Authors: Zhuangt Ping , Butterfield D. Allan 
Published: March 2005

AbstractMembrane‐based bioreactors can greatly influence the rate and extent of chemical reactions and consequently lower the costs associated with the corresponding engineering processes. However, in order to progress in this area, greater understanding of the relationship of the structure and function of bioreactor systems is required. In this study, a proteolytic enzyme, papain (EC 3.4.22.2), was covalently coupled onto the surface of a vinyl alcohol/vinyl butyral copolymer (PVB) membrane employing either glutaraldehyde (GA) or l,l'‐carbonyldiimidazole (CDI). Various kinetic and performance properties of the immobilized papain were studied. It was found that these characteristics of the membrane‐bound papain depended on the immobilization method. The CDI‐immobilized papain bioreactor was used, although the apparent Michaelis constant, Km, of the CDI‐immobilized papain was larger than that of the GA‐immobilized enzyme. In separate experiments, a six‐carbon spacer was also used between the membrane support and the covalently‐linked enzyme. It was found that the insertion of the spacer reduced the disturbance of the enzyme system, resulting in a decreased Km, which was now closer to the value for the free enzyme. Electron paramagnetic resonance (EPR) techniques of spin labeling were used for the first time to examine the conformational change and the active site structure of an enzyme covalently immobilized to a membrane. The structural changes of the active site of papain upon immobilization with and without a spacer were in agreement with the functional properties of the enzyme.
Activity of Thiolsubtilisin in Organic Solvents
Authors: Chatterjee Sudipta , Russell Alan J. 
Published: March 2005

AbstractIn this paper, we compare the activities of subtilisin and thiolsubtilisin in anhydrous organic solvents and in mixtures of water and miscible organic media. The information obtained indicates that changing from one organic solvent to another does not significantly affect the stability of the transition state for the reaction. Thus, since the transition state is charged, it is likely that the active site of the enzyme is electrostatically protected from bulk solvent. Further, since the activities of subtilisin and thiolsubtilisin are different in the solvents used, it is clear that the active site serine is a catalytically important residue in both water and organic solvents.