bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on Scale‐Up Parameters of an Immunoglobulin Separation System Using Protein A Affinity Chromatography
Authors: Kang Kyung A. , Ryu Dewey D. Y.
Published: March 2005

Effects of operational and system parameters on process scale‐up of murine immunoglobulin (IgG2aκ) purification using Protein A affinity chromatography are investigated. Parameters studied are those related to sample application, elution, ligand concentration on support, and column size change. Between sample application velocities of 0.004 and 0.030 cm/s (16‐108 cm/h), the product concentration profiles in eluate did not show significant differences. With given system parameters, the retention time and bandwidth of the peak could be predicted by moment theory. The mean equilibrium constant during elution showed a strong effect of pH between 2 and 4. Within the range of protein A concentrations studied, 0.15‐1.22 mg/mL of gel, the column capacity shows a linear relationship with the concentration of protein A immobilized. Dimensional scale‐up of the column in the radial direction increased the total purification capacity linearly as the cross‐sectional area increased without increasing pressure drop; however, the product concentration was diluted. Scale‐up of the column dimension in the axial direction enables higher concentrations of product in the eluate, although the retention time increases linearly as the gel height increases.
Isolation of Human B‐Cell Subpopulations for Pharmacological Studies
Authors: Bauer Johann , Stünkel Klaus G. E
Published: March 2005

Three groups of human peripheral blood B‐lymphocytes were separated from each other by countercurrent centrifugal elutriation and free‐flow electrophoresis. They differed in their state of maturation and in their capability to produce antibodies in vitro. These B‐cell subpopulations were used to study features of a drug such as BAY R 1005. BAY R 1005 is a synthetic glycolipid analogue (GLA), which is supposed to modulate antibody synthesis. Mature, immunoglobulin‐(Ig‐) secreting B‐lymphocytes secreted equal quantities of antibodies in the presence and in the absence of the GLA. BAY R 1005 was found to be without mitogenic activity on resting B‐cells and did not induce them to produce antibodies. However, it supported the antibody production of preactivated B‐lymphocytes. The in vitro preactivated B‐cells were affected via monocytes. Only in vivo preactivated B‐lymphocytes increased their antibody production under the direct influence of BAY R 1005.
Formation of Bioerodible Polymeric Microspheres and Microparticles by Rapid Expansion of Supercritical Solutions
Authors: Tom Jean W , Debenedetti Pablo G
Published: March 2005

Polyhydroxy acids [poly(L‐lactic acid) (L‐PLA),poly(D,L‐lactic acid) (DL‐PLA), and poly(glycolic acid) (PGA)], biocompatible and bioerodible polymers that are being investigated for controlled delivery of pharmaceuticals and are approved by the Food and Drug Administration for in vivo sutures and bone repair implants, have been dissolved in supercritical CO2 and precipitated by rapid expansion of the resulting supercritical solutions (RESS). The formation of these microparticles and microspheres is a first step toward the goal of producing, in a single processing step, drug‐loaded polymeric microspheres for use in controlled release applications. Nucleation of poly(L‐lactic acid) from CO2 and CO2‐acetone mixtures produced microparticles and microspheres ranging from 4 to 25 μm. Microspheres (2‐20 μm) were also obtained with chlorotrifluoromethane as solvent. Commercial L‐PLA precipitated after extraction of low molecular weight oligomers showed degradation kinetics similar to that of the starting material. The precipitation of DL‐PLA from CO2 produced irregular‐sized particles (10‐20 μm). PGA, a polymer insoluble in most organic solvents, was found to be soluble in supercritical CO2. Nucleation of PGA from CO2 produced both regular‐sized particles and needles of 10–40‐μm length. The total solubility of commercial L‐PLA in supercritical CO2 at 250 bar and 55 °C decreased from 0.14 wt % to less than 0.05 wt % and then leveled off as the cumulative flow of CO2 per unit mass of L‐PLA loaded in the extractor increased beyond 20 standard L of CO2/g of L‐PLA. Use of acetone (1 wt %) as a cosolvent increased L‐PLA solubility by ∼500%.
Thermolytical Techniques To Characterize Fungal Polysaccharides and Bacterial Lipopolysaccharides
Authors: Ramos‐Sánchez M. C , Rodríguez‐Torres A , Leal J. A , Martín‐Gil F. J , Martín‐Gil J
Published: March 2005

The present work constitutes an entirely novel contribution in the scope of microbiology and especially in taxonomy, introducing thermolysis curves as a rapid method of characterization of fungal polysaccharides and bacterial lipopolysaccharides. The thermal analysis techniques applied were thermogravimetry and derivative thermogravimetry (TG‐DTG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Each thermogram of a sample is represented by one or a few temperatures and, in DSC, by complementary enthalpy data. The temperatures of the thermograms from structurally unknown polysaccharides are compared with those used as references, and thus, information on their composition, linkage types, and anomeric configuration can be deduced. The situation is more complicated for bacterial lipopolysaccharides, but in whatever mode, a structural estimation is always possible. In the course of the development and validation of the thermal method, structural findings on relative stabilities of linkage types (valuable in carbohydrate research) have been recognized and are therefore also described in this work.
Effect of Starch Granule Size on Physical Properties of Starch‐Filled Polyethylene Film
Authors: Lim Seung‐Taik , Jane Jay‐Lin , Rajagopalan Shyamala , Seib Paul A.
Published: March 2005

Physical properties of blown films (25‐60‐μm thickness) from compounded mixtures of linear low‐density polyethylene (LLDPE) and starch were investigated. As starch content increased, tensile strength, percent elongation, and light transmittance decreased and film thickness increased. Among the tested films, small‐particle corn starch (2‐μm average diameter) film had the highest elongation rate and tensile and yield strength (560%, 3.15 kg/mm2, and 1.07 kg/mm2, respectively, at 15% starch content). Potato starch (35‐μm average diameter) film had the lowest values (508%, 1.52 kg/mm2, and 0.55 kg/mm2, respectively, at 15% starch content). Potato starch‐LLDPE film had the highest light transmittance and film thickness; small‐particle corn starch had the lowest. Tensile and yield strength of the films had strong negative correlations with average starch granule diameter (R=0.99 and‐0.94, respectively). Film thickness and light transmittance were linearly correlated with starch granule size (R=0.93 and 0.87, respectively). Using small‐particle corn starch substantially increased incorporated starch level in the film while maintaining the film quality.
Microbial Aldonolactone Formation and Hydrolysis: Kinetic and Bioenergetic Aspects
Authors: Noorman H. J. , Rakels J. L. L. , Kuenen J. G. , Luyben K. Ch. A. M. , Heijnen J. J.
Published: March 2005

From previous work, it was observed that during growth on mixtures of acetate and aldose sugars the growth yield of the bacterium Acinetobacter calcoaceticus was increased when aldonolactone hydrolysis occurred. In this paper, the underlying mechanism was investigated by studying the relationship between cellular yield and lactone hydrolysis in a quantitative way. The literature on the kinetics of acid formation from aldono‐lactones was reviewed. It appears that the reaction pattern is composed of lactone isomerization and hydrolysis steps which occur in series. In the acid pH range, lactone interconversion is the rate‐limiting step for acid formation, whereas above pH 7 hydrolysis is slowest. Only for D‐gluconolactone could the detailed mechanistic kinetics be evaluated. For a number of other aldonolactones, including D‐xylono‐ and D‐galactonolactone, an empirical kinetic equation was derived. The reaction rate constants of these lactones are much smaller than for gluconolactone. The kinetic model for the hydrolysis of xylonolactone was experimentally verified, by application of the electrical charge balance to measurement data from A. calcoaceticus cultures. Comparison of the published biomass yield data and the calculated rate of lactone hydrolysis revealed that they do not quantitatively agree. It can be concluded that the observed relation between biomass yield and lactone hydrolysis is only apparent. The results demonstrate the power of the electrical charge balance in the study of processes in which charged compounds are being converted.
The Solution of Hollow Fiber Bioreactor Design Equations
Authors: Jayaraman V. K.
Published: March 2005

A methodology for simplifying the solution procedure for hollow fiber bioreactor design equations has been described. Such a procedure facilitates decoupling of membrane and spongy matrix equations from the tube side equations. The equivalence between the reduced equations and the hemodialyzer problem has been explicitly obtained.
Recombinant Human Insulin
Authors: Ladisch Michael R. , Kohlmann Karen L.
Published: March 2005

Insulin is a well‐characterized peptide that can be produced by recombinant DNA technology for human therapeutic use. A brief overview of insulin production from both traditional mammalian pancreatic extraction and recombinant bacterial and yeast systems is presented, and detection techniques, including electrophoresis, are reviewed. Analytical systems for insulin separation are principally based on reversed‐phase chromatography, which resolves the deamidation product(s) (desamido insulin) of insulin, proinsulin, and insulin. Process‐scale separation is a multistep process and includes ion exchange, reversed‐phase, and size exclusion chromatography. Advantages and/or disadvantages of various separation approaches, as described by the numerous literature references on insulin purification, are presented.
Effects of Glucose Fluctuations on Synchrony in Fed‐Batch Fermentation of Saccharomyces cerevisiae
Authors: Namdev Pradyumna K. , Thompson B. G. , Ward Dennis B. , Gray Murray R.
Published: March 2005

The effects of transient conditions, due to fed‐batch dynamics and fluctuations in glucose supply, on synchronous growth were evaluated by conducting fed‐batch fermentation of Saccharomyces cerevisiae. Chemostat operation with dilution rates of 0.2 and 0.1 h−1 produced periodic oscillations of the CO2 fraction in off‐gas and of the budded fraction of the cell population. A fed‐batch operation with an exponentially increasing glucose feed was started from a synchronized culture established in a chemostat. The CO2 cycles continued for about five cycles (11 h of feed time) and then they disappeared due to gradual decay of synchrony. The fluctuations in glucose supply due to poor mixing were simulated by an intermittent supply of nutrients with a pulse‐on time of 5 s and a pulse‐off time varying from 3 to 39 s according to Monte Carlo method. Such rapid fluctuations in glucose supply during a fed‐batch fermentation immediately produced a chaotic response in CO2 levels which indicated a complete disruption of the synchrony established previously in a chemostat. The elimination of CO2 oscillations was consistent with the measurements of the fraction of budded cells. These results suggest that synchrony cannot be established in large‐scale stirred fermentors due to inherent concentration gradients.
Concentrating Cellulases from Fermented Broth Using a Temperature‐Sensitive Hydrogel
Authors: Park Chang‐Ho , Orozco‐Avila Ignacio
Published: March 2005

A temperature‐sensitive poly(N‐isopropylacrylamide) hydrogel was used to concentrate cellulases from the fermentation broth of Trichoderma reesei. The steady‐state gel volume was less and the gel collapse temperature was lower in fermented broth compared to those in water. Upon a long (24 h) temperature swing for gel swelling, a gel with lower monomer and cross‐linker content showed a larger volume increase, and it took longer to reach a constant volume which was smaller than the steady‐state volume. Upon a long (24 h) temperature swing for gel collapsing, different gels reached the same collapsed volume in a short period of time. The largest volume increase per unit temperature decrease was obtained for a temperature swing between 28 and 33 °C. For short temperature swings (1–5 h), swollen and collapsed gel volumes were reproducible and were approximately the same as the final volumes during long (24 h) swings. Separation efficiency was higher for the gel with a smaller volume change because of higher concentrations of monomer or cross‐linking agent. When the gels were reused, separation efficiency was improved.
Biomimetic Metal‐Sorbing Vesicles: Cd2+ Uptake by Phosphatidylcholine Vesicles Doped with Ionophore A23187
Authors: Van Zanten John H. , Monbouquette Harold G.
Published: March 2005

Unilamellar phosphatidylcholine vesicles, harboring the ionophore, A23187, in the bilayer and the water‐soluble chelating agent, nitrilotriacetate, in the vesicle interior, rapidly sequester and concentrate Cd2+ from dilute aqueous solution. Metal‐sorbing vesicle permeabilities for cadmium ion at 5 ppm (42.8 μM) ranged from 8.09 × 10−7 to 1.27 × 10−4 cm/s for surface A23187 concentrations of 0.22–2.27 pmol/cm2 (which correspond to lipid: carrier molar ratios of 2000:1 to 200:1) and pH's from 5.5 to 8.5. The Cd2+ permeability shows linear variation with carrier concentration under the conditions studied. As pH is decreased, an increasing fraction of the A23187 becomes protonated, and the permeability exhibits a positive linear relationship with a function related to that for the fraction of unprotonated carrier. These noncovalently assembled, metal‐sorbing vesicles exhibit shelf lives of several months and remain stable throughout typical metal sorption studies.
NMR and Microelectrode Studies of Hydrodynamics and Kinetics in Biofilms
Authors: Lewandowski Zbigniew , Altobelli Stephen A. , Fukushima Eiichi
Published: March 2005

Profiles of flow velocity and dissolved oxygen concentration were studied by NMR and microelectrodes near mixed population biofilms growing on polycarbonate substratum. The profile of dissolved oxygen concentration within the diffusion boundary layer and profiles of flow velocity within the hydrodynamic boundary layer can be described by exponential equations.
A Microwave Oven with Variable Continuous Power and a Feedback Temperature Controller
Authors: Tong C. H. , Lentz R. R. , Lund D. B.
Published: March 2005

The power supply circuit of a domestic microwave oven was modified so that the field intensity in the cavity could be changed continuously. The oven was further fitted with a feedback temperature controller for controlling product temperatures during microwave heating by cycling the magnetron on and off. The temperature controller consists of a fiber optic temperature sensing system, a computer, an optocoupler, and a mechanical relay. White bread, moist sponges, and a 5‐mL water load were used to test the performance of the oven. The temperature control capability was greatly influenced by the field intensity of the cavity and less influenced by the data acquisition rate. Experimental data indicated that it was possible to maintain the sample temperature within ±0.3°C at 60°C and within ±0.6 °C at 80°C when a proper power level was used.
Growth, Nutrient Consumption, and End‐Product Accumulation in Sf‐9 and BTI‐EAA Insect Cell Cultures: Insights into Growth Limitation and Metabolism
Authors: Bédard Charles , Tom Rosanne , Kamen Amine
Published: March 2005

Growth, nutrient consumption, and end‐product accumulation were quantitated in shake‐flask cultures of two insect cell lines, Sf‐9 and BTI‐EAA, in three different serum‐supplemented media. Per cell consumption or production rates were calculated for most medium components analyzed. Glucose was growth‐limiting in TNM‐FH medium and was the most important single source of organic‐C for the cells in all cultures. Cells utilized fructose and maltose but not sucrose. α‐Ketoglutarate and malate contributed significantly to the carbon budget of cells in TNM‐FH. Lactate generally did not accumulate during growth. Most of the amino acids were consumed by the cells, with the exception of alanine which was produced. Most of the amino acids appeared to be present in adequate supply in the cultures. Glutamate was generally the most rapidly consumed of the amino acids, followed closely by glutamine. Alanine accumulation was correlated with glucose consumption. In Sf‐9 cultures, ammonia accumulated only slightly or not at all as long as glucose was present in the medium, and uric acid was detectable at the end of growth and in the stationary phase. Added ammonia up to a concentration of 10 mM did not affect the growth of either cell line. Ammonia and lactate may be of less importance in limiting growth in insect cell cultures than in mammalian cell cultures. A hypothetical outline of the major metabolic pathways of the cultured insect cells is presented on the basis of information obtained here and in the literature.
Preparation of Porous Polyurethane Particles and Their Use in Enzyme Immobilization
Authors: Wang X. , Ruckenstein E.
Published: March 2005

Porous polyurethane particles were prepared as follows: (1) Two low molecular weight polymers, namely, poly[methylene(polyphenyl isocyanate)] and poly(propylene glycol) were mixed with stirring at room temperature and allowed to react. (2) The reacted mixture was dispersed with stirring in mineral oil containing small amounts of water, the catalyst dibutyltin dilaurate, and CaCO3 powder. In the presence of the catalyst, the reaction between the two polymers proceeded to completion. Small particles of polyurethane are thus formed which contain mineral oil and CaCO3 as porogens. The particles obtained, separated by filtration, were treated with a solution of HCl in order to generate additional pores, extracted with benzene to eliminate the mineral oil present in the pores, and finally subjected to drying and sieving. The particles were investigated by scanning electron microscopy (SEM), infrared (IR) spectroscopy, and specific surface area measurements. Lipase from Candida rugosa was immobilized by adsorption on the porous polyurethane particles and cross‐linked with glutaraldehyde to enhance the stability of the immobilization. The biocatalytic particles were used for the hydrolysis of triacylglycerides. The high activity of the immobilized enzyme, which per enzyme molecule can be higher than that of the free enzyme, reveals that the porous polyurethane particles constitute excellent supports for lipase.
Mathematical Characterization and Graphical Presentation of the Stiffhess‐Temperature‐Moisture Relationship of Gliadin
Authors: Peleg Micha
Published: March 2005

Published data for storage modulus (G′) vs temperature (T) relationships of gliadin at various moisture contents [deGraaf, E. M.; Madeka, H.; Cocero, A. M.; Kokini, J. Biotechnol Prog. 1993, 9, 210–213] were transformed into relative stiffness, R(T, M), vs temperature and moisture relationships, with the former being defined as R(T, M) = G′(T)/G′(‐50°C). These relationships could be described by the model R(T, M) = 1/{1 + exp[(T ‐ Tc(M)/a(M)]}, where both Tc(M) and a(M), as has been experimentally confirmed, are in the form of a single‐exponential decay term. This model, with the constants of the Tc(M) and a(M) terms incorporated, was also used to create three‐dimensional plots of the relative stiffness‐temperature‐moisture relationship of gliadin at and around its glass tranition, in which the combined effects of moisture and temperature are revealed visually. Although the model applicability is only demonstrated with gliadin data, there is evidence to suggest that it would also be appropriate for other biosolids.
Affinity Thermoprecipitation of Yeast Alcohol Dehydrogenase through Metal Ion‐Promoted Binding with Eudragit‐Bound Cibacron Blue 3GA
Authors: Guoqiang Dong , Benhura Mudadi A. N. , Kaul Rajni , Mattiasson Bo
Published: March 2005

Metal ion‐promoted binding of Saccharomyces cerevisiae alcohol dehydrogenase to Cibacron Blue 3GA was used for its isolation by affinity precipitation with Eudragit‐bound dye. The yeast cells were broken and the cell debris was separated by flocculation with poly(ethylene imine). The supernatant containing the enzyme activity was mixed with Eudragit‐Cibacron Blue in the presence of zinc ions. The precipitation of the affinity complex was induced by the addition of 50 mM CaCl2 and a subsequent increase in temperature to 40 °C. The enzyme was desorbed by treating the precipitate with iminodiacetic acid solution. The procedure resulted in about 66% recovery of enzyme activity with more than 20‐fold purification. Recycling of Eudragit‐dye for enzyme purification was also shown to be possible.
Hairy Root Growth Models: Effect of Different Branching Patterns
Authors: Kim Seungdo , Hopper Elise , Hjortso Martin
Published: March 2005

Root growth occurs by the formation of younger lateral branches on older parent branches. This growth process can be described by the delays that occur between subsequent branching events and summarized by a set of verbal rules describing the branching kinetics in detail. A method for converting such verbal rules to a mathematical model of the branch number in a root culture under constant environmental conditions is presented here. The model of branch number is then combined with an age distribution balance to give a model of the age distribution in a root culture. Exact solution of the model is possible for deterministic branching dynamics, but results in rather cumbersome expressions for large times. Approximate solutions, valid at large times, therefore are obtained from analysis of the model. From these solutions, one readily obtains the specific growth rate of the culture, solely in terms of the branching kinetics. The extension of the modeling concepts presented here to stochastic branching rules is briefly discussed.
Dimensionless Parameters as Design Guidelines for Sterilization of Dead‐Ended Tubes
Authors: Young Jack H. , Lasher William C.
Published: March 2005

Although steam‐in‐place (SIP) is the primary process for sterilization of bioreactors, sterilization guidelines do not exist for equipment design and little quantitative data are available concerning critical parameters such as length, diameter, and orientation of deadlegs. This study correlated microbiological sterilization data with the critical dimensionless parameters governing buoyancy driven convective flow within dead‐ended tubes during SIP sterilization. These parameters were shown to be the overall Grashof number, Grov, and aspect ratio, Ar. Typical values of Grov for bioprocess equipment can range from 103 to 105, while Ar may vary from near 0 to 20 during sterilization of vertical tubes at 121 °C. Reproducible sterilization resulting in a 12 log reduction in B. stearothermophilus spores required an Ar of less than 7 when Grov was 0.7 × 105, whereas an Ar of 12 could be used when Grov was 2.8 × 105.
Nonaqueous Biocatalytic Degradation of a Nerve Gas Mimic
Authors: Yang Fangxiao , Wild James R. , Russell Alan J.
Published: March 2005

Organophosphorus hydrolase has been shown to be an effective catalyst for the continuous decontamination of a nerve agent in a continuous gas phase reactor. Very small quantities of the enzyme are sufficient to enable detoxification of low concentrations of the nerve agent for extended periods of time. In the case where the nerve agent is at high concentrations (a liquid), the enzyme has also been shown to be active in biphasic mixtures of a solvent with water. The activity and specificity of the enzyme in both environments (continuous gas phase and biphasic mixture) obey classical models of enzyme kinetics. The activity of the enzyme in such extreme environments enables optimization of systems capable of continuous gas or liquid phase biocatalytic degradation of highly toxic chemicals.
Studies of High Solidity Ratio Hydrofoil Impellers for Aerated Bioreactors. 2. Air—Water Studies
Authors: Mcfarlane Caroline M. , Zhao Xue ‐Ming , Nienow Alvin W.
Published: March 2005

This second part of a four‐part series of papers reports on the hydrodynamic and power characteristics of two commercial, high solidity ratio, hydrofoil impellers, the Prochem Maxflo T and the Lightnin A315, in an air—water system. Studies were conducted primarily in a mixing vessel of diameter 0.56 m. The influence of operating conditions (impeller speed and gas flow rate) and sparger position and geometry on bulk flow patterns, gas filled cavity formation, and power consumption have been investigated in detail. In the turbulent Reynolds number region, the unaerated impeller power numbers are constant with average values of 1.30 for the Prochem and 0. 76–0.84 for the A315, depending on impeller position relative to the base of the vessel. Gassed power consumption is closely linked to cavity type and flow pattern. In particular, the development of large cavities causes a significant reduction in power drawn, impeller pumping capacity, and gas dispersion capability. As with downward pumping mixed flow impellers, two characteristic gas loading regimes, direct and indirect loading, can be identified. Under certain conditions, severe hydrodynamic instabilities over the transition between the two regimes give rise to very large torque and power fluctuations. Changes in reactor geometry can have a significant effect on impeller performance. Thus, sparger type and position have a strong influence on relative power drawn, gas handling capability, power required to disperse gas and stability of operation. Of the configurations studied, the use of a large ring sparger (DS/D = 0.8D) at a large sparger—impeller separation is suggested, since relative power drawn, gas handling capability, and energy efficiency in dispersing gas are all enhanced.
Allostatic Load of Men and Women in Early Middle Age
Authors: Kinnunen Marja-Liisa , Kaprio Jaakko , Pulkkinen Lea
Published: March 2005

Abstract. The present longitudinal study investigated three aspects of allostatic load, a long-term negative consequence of physical responses to stress: (1) sex differences in allostatic load in early middle age, (2) associations between career stability history and allostatic load, and (3) relationships between allostatic load and health problems. Participants consisted of 62 men and 55 women from the ongoing Jyväskylä Longitudinal Study of Personality and Social Development, Finland. Allostatic load was the sum of eight parameters (dehydroepiandrosterone-sulfate, 12-h urinary norepinephrine, high-density lipoprotein, triglycerides, glycosylated hemoglobin, systolic and diastolic blood pressure, and waist-to-hip ratio) for which the participant fell into the high-risk quartile. Results showed that 41.9% of men and 21.8% of women had an elevated allostatic load at age 42. Participants with preceding unstable career assessed prospectively at age 36 had an over three-fold risk for high allostatic load six years later compared to participants with a stable career history; sex, alcohol consumption, and smoking were adjusted for in the models. Furthermore, participants with high allostatic load reported having more psychosomatic symptoms. The results reveal that an unstable career as a long-term stressful life condition may have long-lasting effects on health.
The Two Components of Social Desirability and their Relations to Resting Frontal Brain Asymmetry
Authors: Pauls Cornelia A. , Wacker Jan , Crost Nicolas W.
Published: March 2005

Abstract. The aim of the present study was to investigate the relationships between resting frontal hemispheric asymmetry (FHA) in the low α band (8-10.25 Hz) and the two components of socially desirable responding, i.e., self-deceptive enhancement (SDE) and impression management (IM), in an opposite-sex encounter. In addition, Big Five facets, self-reports of emotion, and spontaneous eye blink rate (BR), a noninvasive indicator of functional dopamine activity, were assessed. SDE as well as IM were related to relatively greater right-than-left activity in the low α band (i.e., relative left frontal activation; LFA) and to self-reported positive affect (PA), but only SDE was related to BR. We hypothesized that two independent types of motivational approach tendencies underlie individual differences in FHA and PA: affiliative motivation represented by IM and agentic incentive motivation represented by SDE. Whereas the relationship between SDE and PA was mediated by BR, the relationship between SDE and FHA was not.
An Overview of Research into the Cognitive Basis of Intelligence
Authors: Schweizer Karl
Published: March 2005

Abstract. This paper provides an overview of the research into the cognitive basis of intelligence. This research explains cognitive abilities in terms of cognitive units or properties of such units. Furthermore, this research is characterized by the application of so-called elementary cognitive tasks. The various approaches of this research originate from the concepts of cognitive psychology: Mental (and perceptual) speed, attention, working memory, memory access, and learning. All the approaches led to measures which correlate with measures of intelligence. The enormous importance of the cognitive basis is highlighted by the observation that predictors taken from the various approaches explain approximately 50% of the variance of intelligence. At the latent level the rate of explanation seems to surmount the 70% barrier. Furthermore, the problems and perspectives of the approaches are addressed.
Investigation of the relationship between chemical composition and size distribution of airborne particles by partial least squares and positive matrix factorization
Authors: Zhou Liming , Hopke Philip K. , Stanier Charles O. , Pandis Spyros N. , Ondov John M. , Pancras J. Patrick
Published: March 2005

Two multivariate data analysis methods, partial least square (PLS) and positive matrix factorization (PMF), were used to analyze aerosol size distribution data and composition data. The relationships between the size distribution data and composition data were investigated by PLS. Three latent variables summarized chemical composition data and most variations in size distribution data especially for large particles and proved the existence of the linearity between the two data sets. The three latent variables were associated with traffic and local combustion sources, secondary aerosol, and coal‐fired power plants. The size distribution, particle composition, and gas composition data were combined and analyzed by PMF. Source information was obtained for each source using size distribution and chemical composition simultaneously. Eleven sources were identified: secondary nitrate 1 and 2, remote traffic, secondary sulfate, lead, diesel traffic, coal‐fired power plant, steel mill, nucleation, local traffic, and coke plant.
NEDD4-2 (neural precursor cell expressed, developmentally down-regulated 4-2) negatively regulates TGF-β (transforming growth factor-β) signalling by inducing ubiquitin-mediated degradation of Smad2 and TGF-β type I receptor
Authors: KURATOMI Go , KOMURO Akiyoshi , GOTO Kouichiro , SHINOZAKI Masahiko , MIYAZAWA Keiji , MIYAZONO Kohei , IMAMURA Takeshi
Published: March 2005

Inhibitory Smad, Smad7, is a potent inhibitor of TGF-β (transforming growth factor-β) superfamily signalling. By binding to activated type I receptors, it prevents the activation of R-Smads (receptor-regulated Smads). To identify new components of the Smad pathway, we performed yeast two-hybrid screening using Smad7 as bait, and identified NEDD4-2 (neural precursor cell expressed, developmentally down-regulated 4-2) as a direct binding partner of Smad7. NEDD4-2 is structurally similar to Smurfs (Smad ubiquitin regulatory factors) 1 and 2, which were identified previously as E3 ubiquitin ligases for R-Smads and TGF-β superfamily receptors. NEDD4-2 functions like Smurfs 1 and 2 in that it associates with TGF-β type I receptor via Smad7, and induces its ubiquitin-dependent degradation. Moreover, NEDD4-2 bound to TGF-β-specific R-Smads, Smads 2 and 3, in a ligand-dependent manner, and induced degradation of Smad2, but not Smad3. However, in contrast with Smurf2, NEDD4-2 failed to induce ubiquitination of SnoN (Ski-related novel protein N), although NEDD4-2 bound to SnoN via Smad2 more strongly than Smurf2. We showed further that overexpressed NEDD4-2 prevents transcriptional activity induced by TGF-β and BMP, whereas silencing of the NEDD4-2 gene by siRNA (small interfering RNA) resulted in enhancement of the responsiveness to TGF-β superfamily cytokines. These data suggest that NEDD4-2 is a member of the Smurf-like C2-WW-HECT (WW is Trp-Trp and HECT is homologous to the E6-accessory protein) type E3 ubiquitin ligases, which negatively regulate TGF-β superfamily signalling through similar, but not identical, mechanisms to those used by Smurfs.
Co-expression of glutaminase K and L isoenzymes in human tumour cells
Authors: PÉREZ-GÓMEZ Cristina , CAMPOS-SANDOVAL José A. , ALONSO Francisco J. , SEGURA Juan A. , MANZANARES Elisa , RUIZ-SÁNCHEZ Pedro , GONZÁLEZ María E. , MÁRQUEZ Javier , MATÉS José M.
Published: March 2005

The pattern of expression of glutaminase isoenzymes in tumour cells has been investigated to clarify its role in the malignant transformation and the prospect of its use as a clinically relevant factor. Using leukaemia cells from medullar blood of human patients and several established human cancer cell lines, we have developed a competitive RT (reverse transcriptase)-PCR assay to quantify simultaneously K-type (kidney-type) and L-type (liver-type) glutaminase mRNAs. Co-expression of both transcripts and higher amounts of L-type mRNA were always found in all cancer cell types analysed. However, mature lymphocytes from the medullar blood of a patient suffering aplasia did not express the K-type transcript and showed a 15-fold increase of L-type transcript. Co-expression was also confirmed at the protein level using isoform-specific antibodies; nevertheless, it did not correlate with the relative abundance of glutaminase transcripts and strong K-type protein signals were detected. On the other hand, marked differences were found with regard to glutamate inhibition and phosphate activation of tumour glutaminase activity. Taken together, the protein data suggest that K isoform would account for the majority of glutaminase activity in these human tumour cells. The results confirm that simultaneous expression of both isoenzymes in human cancer cells is a more frequent event than previously thought. Furthermore, the present work and other previous data suggest that K isoform is up-regulated with increased rates of proliferation, whereas prevalence of the L isoform seems to be related with resting or quiescent cell states.
Characterization of the molecular forms of glutathione S-transferase P1 in human gastric cancer cells (Kato III) and in normal human erythrocytes
Authors: RANGANATHAN Perungavar N. , WHALEN Richard , BOYER Thomas D.
Published: March 2005

GSTP1 (glutathione S-transferase pi) is involved in stress responses and in cellular proliferation pathways as an inhibitor of JNK (c-Jun N-terminal kinase). It has been proposed that monomeric GSTP1 functions as a JNK inhibitor. All of the studies to date have been performed using rodent cells, and it is unclear if monomeric GSTP1 exists in human cells. Monomeric GSTP1 was sought in human gastric cancer cells (Kato III) and in normal human erythrocytes using gel filtration, ELISA and Western blots. Monomeric GSTP1 was found in conditioned medium, in cytosol of Kato III cells and in cytosol of erythrocytes. GSTP1 subunits from Kato III cells and erythrocytes were heterogeneous when analysed by MALDI–TOF (matrix-assisted laser-desorption ionization–time-of-flight) MS, suggesting that there were post-translational modifications to GSTP1. One post-translational modification, phosphorylation of a serine residue in the C-terminal portion of GSTP1 where JNK binds, was identified in GSTP1 purified from Kato III cells, but not in GSTP1 purified from human erythrocytes. Therefore normal and malignant human cells contain GSTP1 monomers with post-translational modifications, and it is likely that GSTP1 monomers regulate JNK activity in human cells in the same manner as in rodent cells.
Near-infrared spectroscopy of ethylene and ethylene dimer in superfluid helium droplets
Authors: Scheele Iris , Conjusteau André , Callegari Carlo , Schmied Roman , Lehmann Kevin K. , Scoles Giacinto
Published: March 2005

The ν5+ν9 spectra of ethylene, C2H4, and its dimer, solvated in helium nanodroplets, have been recorded in the wavelength region near 1.6μm. The monomer transitions show homogeneous broadening of ≈0.5cm−1, which is interpreted as due to an upper state vibrational relaxation lifetime of ≈10ps. Nearly resonant vibrational energy transfer (ν5+ν9→2ν5) is proposed as the relaxation pathway. The dimer gives a single unresolved absorption feature located 4cm−1 to the red of the monomer band origin. The scaling of moments of inertia upon solvation in helium is 1.18 for the monomer and >2.5 for the dimer. In terms of the adiabatic following approximation, this classifies the monomer as a fast rotor and the dimer as a slow rotor.
Single filament electrophoresis of F-actin and filamentous virus fd
Authors: Li Guanglai , Wen Qi , Tang Jay X.
Published: March 2005

We have developed an electrophoretic cell suitable for single-molecule electrophoresis. The setup works for fluorescently labeled macromolecules by direct recording of their motion under an external electric field. The electrophoretic mobility of rodlike, polydisperse actin filaments (F-actin) were measured, as well as its dependence on the orientation of the filaments. A dipping effect is observed and quantitatively accounted for by the difference in hydrodynamic drag between motions along and perpendicular to the long axis of a filament. When averaged over all orientations, the mobility of F-actin in 50mM KCl and 2mM MgCl2 is determined to be −(8.5±0.7)×10−5cm2∕(Vs). This method is also used to compare the mobility of F-actin and fd virus in a mixture of them. A reliable ratio of 1.26 is measured for fd virus to F-actin. The influence of the orientation dependent drag on electrophoretic mobility is discussed and a strategy for reliable measurement is proposed.
Magnetic tunnel junctions with a zinc oxide–cobalt oxide composite tunnel barrier
Authors: Le Brizoual L. , Alnot P. , Hehn M. , Montaigne F. , Alnot M. , Schuhl A. , Snoeck E.
Published: March 2005

Composite CoO–ZnO tunnel junctions showing nonlinear and asymmetric current-voltage characteristics with significant magnetoresistance ratios (up to 8% at 77 K) have been prepared by using reactive sputtering from a zinc target. Electron transmission microscopy demonstrates the formation of a zinc oxide–cobalt oxide bilayer. Observed asymmetries, which are directly linked to the difference in zinc oxide and cobalt oxide barrier heights are in good agreement with calculations done within the framework of a parabolic bands model, using thicknesses extracted from transmission electron microscopy (TEM) images and barrier heights found in literature.
Viral genetic determinants for thrips transmission of Tomato spotted wilt virus
Authors: Sin Sang-Hoon , McNulty Brian C. , Kennedy George G. , Moyer James W.
Published: March 2005

Tomato spotted wilt virus (TSWV) is transmitted exclusively by thrips in nature. A reassortment-based viral genetic system was used to map transmissibility by thrips to the medium (M) RNA of TSWV. To locate determinants of thrips transmission in the M RNA, 30 single-lesion isolates (SLIs) were generated from a single TSWV isolate that was inefficiently transmitted by thrips. Three of the 30 SLIs were transmitted by thrips, and 27 were not. Sequence analysis of the M RNA, thrips transmissibility assays, G
C
protein analysis, and transmission electron microscopic studies revealed that a specific nonsynonymous mutation (C1375A) in the G
N
/G
C
ORF of the M RNA resulted in the loss of thrips transmissibility without inhibition of virion assembly. This was in contrast to other nontransmissible SLIs, which had frameshift and/or nonsense mutations in the G
N
/G
C
ORF but were defective in virion assembly. The G
C
glycoprotein was detectable in the C1375A mutants but not in the frameshift or nonsense mutants. We report a specific viral determinant associated with virus transmission by thrips. In addition, the loss of transmissibility was associated with the accumulation of defective haplotypes in the population, which are not transmissible by thrips, rather than with the presence of a dominant haplotype that is inefficiently transmitted by thrips. These results also indicate that the glycoproteins may not be required for TSWV infection of plant hosts but are required for transmissibility by thrips.
A binding mechanism in protein–nucleotide interactions: Implication for U1A RNA binding
Authors: Guallar Victor , Borrelli Kenneth W.
Published: March 2005

We present a close electronic view of the protein–base interface for the N-terminal domain of the human protein U1A. Combining accurate mixed quantum mechanics/molecular mechanics techniques and protein structure prediction methods, we provide a detailed electronic structure description of the protein–RNA stacking interactions. Our analysis indicates the evolution of the protein structure optimizing the interaction between Asp-92 and the RNA bases. The results show a direct coupling of the C-terminal tail and Asp-92, providing a direct rationalization of the experimentally determined role of the C-terminal domain in RNA binding. Here, we propose a mechanism where a protein side chain, with a delocalized electronic pi system, assists in the nucleotide binding. The binding mechanism involves a short-range interaction of the side chain with the nucleotide base and an electronic long-range interaction through a sandwich-stacking motif. The structural motif of the binding mechanism is observed in similar protein–RNA interactions and in various protein-ATP-binding sites.
Implications of an antiparallel dimeric structure of nonphosphorylated STAT1 for the activation–inactivation cycle
Authors: Zhong Minghao , Henriksen Melissa A. , Takeuchi Kenji , Schaefer Olaf , Liu Bin , Hoeve Johanna ten , Ren Zhiyong , Mao Xiang , Chen Xiaomin , Shuai Ke , Darnell James E.
Published: March 2005

IFN-γ treatment of cells leads to tyrosine phosphorylation of signal transducer and activator of transcription (STAT) 1 followed by dimerization through a reciprocal Src homology 2–phosphotyrosine interaction near the –COOH end of each monomer, forming a parallel structure that accumulates in the nucleus to drive transcription. Prompt dephosphorylation and return to the cytoplasm completes the activation–inactivation cycle. Nonphosphorylated STATs dimerize, and a previously described interface between N-terminal domain (ND) dimers has been implicated in this dimerization. A new crystal structure of nonphosphorylated STAT1 containing the ND dimer has two possible configurations for the body of STAT1, one of which is antiparallel. In this antiparallel structure, the Src homology 2 domains are at opposite ends of the dimer, with the coiled:coil domain of one monomer interacting reciprocally with the DNA-binding domain of its partner. Here, we find that mutations in either the coiled:coil/DNA-binding domain interface or the ND dimer interface block dimerization of nonphosphorylated molecules and cause a resistance to dephosphorylation
in vivo
and resistance to a tyrosine phosphatase
in vitro
. We conclude that a parallel STAT1 phosphodimer not bound to DNA most likely undergoes a conformational rearrangement (parallel to antiparallel) to present the phosphotyrosine efficiently for dephosphorylation.
City Centre Regeneration in the Context of the 2001 European Capital of Culture in Porto, Portugal
Authors: Balsas Carlos J. L.
Published: March 2005

In 2001, the city of Porto hosted the European Capital of Culture event. ‘Porto 2001’ was a year-long programme of arts, cultural events and urban regeneration activities. The purpose of this article is to discuss the city centre regeneration operation conducted in conjunction with the European Capital of Culture initiative in Porto. My objective is to extract a set of lessons learned that can be useful to other cities pursuing the same designation and strategy. The key finding is that despite rich and well-participated cultural events, too much emphasis was put on attracting public investment to regenerate the public space, replacing infrastructures, and modernizing cultural facilities. This was done at the expense of institutional capacity building and boosting civic creativity.
The ANC's ‘Left Turn’ & South African sub-imperialism
Authors: Bond Patrick
Published: March 2005

The South African government is widely considered to play a progressive role in Africa and the world. Indeed, there was an expectation after the 2004 election that Pretoria would be part of a global backlash against neoliberalism. However, the radical rhetoric often emanating from Pretoria these days barely disguises its post-apartheid record of promoting of strategies which promote global integration. These include the New Partnership for Africa's Development (NEPAD); ‘normalised’ bilateral military relations with the Pentagon and geopolitical alliances with Washington across Africa; trade liberalisation; collaboration with Western financial power and facilitation of transnational capital in Africa; and opposition to demands for reparations for the West's apartheid-era profits. While some academic commentators have not yet grasped the essential nature of this policy direction, activists in the African Social Forum networks have periodically demanded the adoption of alternative strategies. Their vision is grounded in values of social justice and international solidarity; Pretoria's appears to be merely sub-imperialist.
The consequences of Zipf's law for syntax and symbolic reference
Authors: Ferrer i Cancho Ramon , Riordan Oliver , Bollobás Béla
Published: March 2005

Although many species possess rudimentary communication systems, humans seem to be unique with regard to making use of syntax and symbolic reference. Recent approaches to the evolution of language formalize why syntax is selectively advantageous compared with isolated signal communication systems, but do not explain how signals naturally combine. Even more recent work has shown that if a communication system maximizes communicative efficiency while minimizing the cost of communication, or if a communication system constrains ambiguity in a non-trivial way while a certain entropy is maximized, signal frequencies will be distributed according to Zipf's law. Here we show that such communication principles give rise not only to signals that have many traits in common with the linking words in real human languages, but also to a rudimentary sort of syntax and symbolic reference.