bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and catalytic response to temperature and cosolvents of carboxylesterase EST1 from the extremely thermoacidophilic archaeon Sulfolobus solfataricus P1
Authors: Sehgal Amitabh C. , Tompson Richele , Cavanagh John , Kelly Robert M. 
Published: October 2002

AbstractThe interactive effects of temperature and cosolvents on the kinetic and structural features of a carboxylesterase from the extremely thermoacidophilic archaeon Sulfolobus solfataricus P1 (Sso EST1) were examined. While dimethylformamide, acetonitrile, and dioxane were all found to be deleterious to enzyme function, dimethyl sulfoxide (DMSO) activated Sso EST1 to various extents. This was particularly true at 3.5% (v/v) DMSO, where kcat was 20–30% higher than at 1.2% DMSO, over the temperature range of 50–85°C. DMSO compensated for thermal activation in some cases; for example, kcat at 60°C in 3.5% DMSO was comparable to kcat at 85°C in 1.2% DMSO. The relationship between DMSO activation and enzyme structural characteristics was also investigated. Nuclear magnetic resonance spectroscopy and circular dichroism showed no gross change in enzyme conformation with 3.5% DMSO between 50 and 80°C. However, low levels of DMSO were shown to have a small yet significant change in enzyme conformation. This was evident through the reduction of Sso EST1's melting temperature and changes in the microenvironment of the enzyme's tyrosine and tryptophan residues at 3.5% versus 1.2% (v/v) solvent. Finally, activation parameter analysis based on kinetic data, at 1.2% and 3.5% DMSO, implied an increase in conformational flexibility with additional cosolvent. These results suggest the activating effect of DMSO was related to small changes in the enzyme's structure resulting in an increase in its conformational flexibility. Thus, in addition to their use for solubilizing hydrophobic substrates in water, cosolvents may also serve as activators in applications involving thermostable biocatalysts at sub‐optimal temperatures. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 784–793, 2002.
Effect of gene location, mRNA secondary structures, and RNase sites on expression of two genes in an engineered operon
Authors: Smolke Christina D. , Keasling Jay D. 
Published: October 2002

AbstractThe effects of endoribonuclease sites, secondary structures in mRNA, and gene placement on protein production and mRNA stability and steady‐state levels were tested in a dual‐gene operon containing the genes encoding β‐galactosidase (lacZ) from Escherichia coli and green fluorescent protein (gfp) from Aequorea victoria. Two previously identified RNase E sites were placed separately between the coding regions to direct cleavage in this area and produce two secondary transcripts, each containing a single‐gene coding region. Novel secondary structures were engineered into the 3′ and 5′ ends of each of the coding regions to protect the transcript from inactivation by endoribonucleases (5′ hairpins) and degradation by exoribonucleases (3′ hairpins). In addition, the effects of relative gene placement were examined by switching the locations of the two coding regions. Depending on the particular secondary structures and RNase E sites placed between the genes the relative steady‐state transcript and protein levels encoded by the two reporter genes could be changed up to 2.5‐fold and 4‐fold, respectively. By changing gene location and incorporating secondary structures and RNase E sites the relative steady‐state transcript and protein levels encoded by the two reporter genes could be changed up to 100‐fold and 750‐fold, respectively. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 762–776, 2002.
Modeling, optimization and experimental assessment of continuous L‐(−)‐carnitine production by Escherichia coli cultures
Authors: Alvarez‐Vasquez Fernando , Cánovas Manuel , Iborra José L. , Torres Néstor V. 
Published: October 2002

AbstractIn a previous paper Cánovas et al. (Biotechnol Bioeng 2002;77:764–775) presented a model for L‐(−)‐carnitine production using Escherichia coli O44 K74, in a cell‐recycle bioreactor for the biotransformation of crotonobetaine into L‐carnitine. In this work we optimize this biotechnological setup and experimentally verify the predicted optimal parameter profiles. Provided with a reliable and robust S‐system description of the cell–bioreactor combined system, we applied the Indirect Optimization Method described by Torres et al. (Biotechnol Bioeng 1997;55(5):758–772; Food Technol Biotechnol 1998;36(3):177–184). This optimization approach provides different parameter value profiles, all of which are compatible with the cell physiology and the bioreactor operating conditions, that yield increased rates of L‐(−)‐carnitine production. Three parameters were seen to be of critical importance for maximizing L‐(−)‐carnitine production: the dilution rate, the initial crotonobetaine concentration, and the carnitine dehydratase activity. When the first two were changed in the experimental setup, there was a 74% increase in the L‐(−)‐carnitine production rate, performance that was in close agreement with the predictions of the model. In accordance with the optimized solution, a further improvement (90% increase in the L‐(−)‐carnitine production rate) could be attained by over‐expressing up to 5 times the carnitine dehydratase basal activity. Thus the optimization approach shown herein provides experimental evidence of a new strategy which demonstrates the possible variables that can be subjected to modifications compatible with the cell physiology and bioreactor operating conditions, and which are able to yield increased rates of L‐(−)‐carnitine production. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 794–805, 2002.
Hepatitis B surface antigen (HBsAg) expression in plant cell culture: Kinetics of antigen accumulation in batch culture and its intracellular form
Authors: Smith Mark L. , Mason Hugh S. , Shuler Michael L. 
Published: October 2002

AbstractThe production of edible vaccines in transgenic plants and plant cell culture may be improved through a better understanding of antigen processing and assembly. The hepatitis B surface antigen (HBsAg) was chosen for study because it undergoes substantial and complex post‐translational modifications, which are necessary for its immunogenicity. This antigen was expressed in soybean (Glycine max L. Merr. cv Williams 82) and tobacco NT1 (Nicotiana tabacum L.) cell suspension cultures, and HBsAg production in batch culture was characterized. The plant‐derived antigen consisted predominantly of disulfide cross‐linked HBsAg protein (p24s) dimers, which were all membrane associated. Similar to yeast, the plant‐expressed HBsAg was retained intracellularly. The maximal HBsAg titers were obtained with soybean suspension cultures (20–22 mg/L) with titers in tobacco cultures being approximately 10‐fold lower. For soybean cells, electron microscopy and immunolocalization demonstrated that all the HBsAg was localized to the endoplasmic reticulum (ER) and provoked dilation and proliferation of the ER network. Sucrose gradient analysis of crude extracts showed that HBsAg had a complex size distribution uncharacteristic of the antigen's normal structure of uniform 22‐nm virus‐like particles. The extent of authentic epitope formation was assessed by comparing total p24s synthesized to that reactive by polyclonal and monoclonal immunoassays. Depending on culture age, between 40% and 100% of total p24s was polyclonal antibody reactive whereas between 6% and 37% was recognized by a commercial monoclonal antibody assay. Possible strategies to increase HBsAg production and improve post‐translational processing are discussed. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80:812–822, 2002.
Visual color matching under various viewing conditions
Authors: Komatsubara Hitoshi , Kobayashi Shinji , Nasuno Nobuyuki , Nakajima Yasushi , Kumada Shuichi 
Published: October 2002

AbstractIn this article, we provide colorimetry data for which it was judged that the colors between different media matched under various viewing conditions. Painted color patches, a monitor, and printed color patches were used in the color matching experiments, in which we compared the appearances of the painted color patch and the monitor, or the monitor and the printed color patch, using the method of constant stimuli. The nine types of viewing conditions we used could be envisaged to occur when comparing different device outputs indoors. The experimental data obtained were compared with corresponding colors predicted with the use of five types of color appearance model, including color appearance formulae. We found that when the viewing conditions were the same for the different media, there was good agreement between the experimental data and the CIECAT94 model. And by adjusting the brightness induction and the chromatic induction factors, it was possible to improve conformity for the lightness and the chromaticity. Moreover, it was possible to improve the white point shift, which cannot be adjusted with the use of optimized parameters by introducing incomplete adaptation. By optimizing the parameters and introducing incomplete adaptation, it is possible to make the mean color difference ΔE between the corresponding color and the color matching point less than 10 CIELAB units for all of the viewing conditions.
Proposed metameric indices for goniochromatic objects
Authors: Medina Ruiz J. M. 
Published: October 2002

AbstractAs a means of determining the degree of metamerism for goniochromatic objects, a generalized illuminant metamerism index for changes in spectral composition of illuminants has been formulated based on a modified LABD index. This index takes into account factors such as color memory and could be used under paramerism conditions. Consequently, a geometric metamerism and a flop index is also presented. Nevertheless, their estimation is based on the establishment of goniochromatic discrimination functions. All these concepts could be useful in many industrial‐coating applications to achieve an overall measure of variation in goniochromatism on metallic materials.
Chromaticity contour map of the RGB cube: A simple algorithm
Authors: Brill Michael H. 
Published: October 2002

AbstractA simple algorithm (amenable to spreadsheets) is described for plotting a luminance contour map of the color gamut of an additive‐primary display given the chromaticities of its primaries and screen white. Each contour of the plot represents (in either r,g or x,y coordinates) the polygon of intersection of the RGB cube with a plane of constant Y. Each vertex on a contour is an intersection of 1 of the 12 edges of the RGB cube with the constant‐Y plane. Feasibility of an edge as a vertex of the polygon is tested through comparison of the computed r,g coordinates with functions of the luminosity coefficients of the primaries. By ordering the RGB‐cube edges in a particular way prior to scanning them for feasibility, one is guaranteed to retrieve the vertices of any constant‐Y polygon in convex order. This fact facilitates plotting of the polygons.
Defining a practical method of ascertaining textile color acceptability
Authors: Steen Daniel , Dupont Daniel 
Published: October 2002

AbstractThe relations between supplier and customer are today more important than they have ever been. However, conflicts do sometimes arise between them, deriving from differences in the judgment of color matchings. Colorimetry's role is precisely to avoid such conflicts through instrument measurements. A study was made on the pass/fail problems, based on 1,830 measurements and observations made in industrial textile firms, followed by 350 new tests. Human judgments are as liable to errors as instrument measurements, because the surface effects are often misleading for the observer. This study proposes a sorting method that combines the differences deriving from measurements by colorimetric instruments and by visual judgment. The Color Measurement Committee (CMC) equation, widely used in the textile field, has given excellent practical results. The CIE94 equation, which uses the same principle of ellipsoid tolerance, offers a mathematical simplification as well as further information on the sample observation conditions in order to determine color differences. Nevertheless, these two equations are different, and the CIE94 indexes must not be interpreted with the same tolerances as those of the CMC. Pending the CIE recommendations concerning textile samples, new acceptability tolerances should be redetermined for the CIE94. This article presents an innovative way of calculating metameric indexes that, when coupled with acceptability equations, allow the agreement rate between visual judgment and automatic selection to be increased.
The metabolic demands of driving for drivers with type 1 diabetes mellitus
Authors: Cox Daniel J. , Gonder‐Frederick Linda A. , Kovatchev Boris P. , Clarke William L. 
Published: October 2002

AbstractBackgroundThe active cognitive‐motor demands of driving may have a significant metabolic demand that could contribute to the development of hypoglycemia. Conversely, symptoms caused by the stress of driving may be confused with hypoglycemia and lead to false alarms. This study examined the metabolic demand and the physiological stress of driving on type 1 diabetes mellitus (T1DM) drivers.MethodsForty‐three T1DM drivers were placed on a constant insulin infusion/variable dextrose infusion to maintain euglycemia for 30 min while either watching a driving video or actually driving a simulator, in a counterbalanced crossover design. Dextrose infusion, heart rate, epinephrine, and subjective symptom ratings were measured every 5 min. Additionally, subjects were monitored for self‐treatment (drinking soda).ResultsWhile blood glucose (BG) levels were equivalent across both conditions, actual driving was associated with a higher dextrose infusion rate (p = 0.02), more autonomic symptoms (p < 0.05), increased heart rate (p < 0.001), a trend (p = 0.09) for greater epinephrine release, and more frequent hypoglycemic self‐treatment (p < 0.001).ConclusionsDriving is a task with a significant metabolic demand, which may lower BG, and also that driving stress may be associated with symptoms similar to those of hypoglycemia. Physicians should discuss with their T1DM patients hypoglycemia and driving, and encourage measuring blood glucose before driving and during long drives. Copyright © 2002 John Wiley & Sons, Ltd.
Cytokine detection by ELISPOT: relevance for immunological studies in type 1 diabetes
Authors: Meierhoff Guido , Ott Patrick A. , Lehmann Paul V. , Schloot Nanette C. 
Published: October 2002

AbstractDiabetes mellitus type 1 is a chronic disease in which the insulin‐secreting ß‐cells are selectively destroyed by an immune‐mediated process. Autoantibodies directed against several islet antigens are useful parameters to estimate the risk to develop diabetes, but cell‐mediated immunity involving T lymphocytes plays a major part in causing the specific destruction of ß‐cells. T cells are characterized by their antigen‐specificity, phenotype and cytokine‐secreting profile. T cells that secrete cytokines of the T helper 1 (Th1) type have been shown to transfer diabetes in animal studies, in contrast to T helper 2 (Th2) cytokine‐secreting T cells that are thought to be rather nondestructive. In the absence of phenotypic markers for Th1 and Th2 cells, several different approaches have been taken to examine T cell responses in detail. Methods involve T‐cell proliferation assays, Enzyme‐Linked‐Immuno‐Sorbent‐Assay (ELISA) analysis of secreted cytokines and phenotype analysis applying flow cytometry. A more recent development is ELISPOT analysis, which enables the investigator to determine the qualitative and quantitative antigen‐specific immune response on a single‐cell level with regard to cytokine secretion. This article aims to give an introduction to the advantages and limitations inherent in the different techniques and their potential relevance for immunological studies in diabetes mellitus type 1. Copyright © 2002 John Wiley & Sons, Ltd.
Contributions of endothelin‐1 and sodium hydrogen exchanger‐1 in the diabetic myocardium
Authors: Hileeto Denise , Cukiernik Mark , Mukherjee Suranjana , Evans Terry , Barbin Yousef , Downey Donal , Karmazyn Morris , Chakrabarti Subrata 
Published: October 2002

AbstractBackgroundEndothelin‐1 (ET‐1) and sodium hydrogen exchanger‐1 (NHE‐1) are important mediators of several disease processes affecting the heart, especially relating to myocardial ischemia. There is evidence that their actions may be interrelated. Their contributions to diabetic heart disease have not been extensively documented. Accordingly, the aim of this study was to investigate the interactive roles of ET‐1 and NHE‐1 in the pathogenesis of diabetic cardiomyopathy, a significant cause of morbidity in diabetic patients.MethodsStreptozotocin‐induced diabetic Sprague Dawley rats were treated with NHE‐1 blocker cariporide or dual ETA/ETB blocker bosentan and were subsequently studied one, three and six months after induction of diabetes. These animals were compared with nondiabetic rats as well as with diabetic rats on poor blood glucose control.ResultsDiabetes leads to hyperglycemia, reduced body weight gain and increased glycated hemoglobin levels. These animals exhibited focal myocardial fibrosis and increased ejection fraction, in association with a tendency to increased left ventricular wall thickness and heart weight, after six months of follow‐up, both bosentan and cariporide prevented these responses. Diabetes also caused significant increases in ET‐1 mRNA and protein expression in the heart at all time points, which was further augmented by cariporide treatment for three months. Diabetes did not affect either mRNA or protein expression of NHE‐1, although these did decrease in hearts of diabetic animals treated with bosentan for six months.ConclusionsThese results indicate an important contribution of both ET‐1 and NHE‐1 in the pathogenesis of diabetic cardiomyopathy. These data suggest that NHE‐1 may act as a downstream mediator in the production of ET‐induced functional and structural changes in the myocardium in diabetes. Copyright © 2002 John Wiley & Sons, Ltd.
On the relationship between dynamic visual and auditory processing and literacy skills; results from a large primary‐school study
Authors: Talcott Joel B. , Witton Caroline , Hebb Gillian S. , Stoodley Catherine J. , Westwood Elizabeth A. , France Susan J. , Hansen Peter C. , Stein John F. 
Published: October 2002

AbstractThree hundred and fifty randomly selected primary school children completed a psychometric and psychophysical test battery to ascertain relationships between reading ability and sensitivity to dynamic visual and auditory stimuli. The first analysis examined whether sensitivity to visual coherent motion and auditory frequency resolution differed between groups of children with different literacy and cognitive skills. For both tasks, a main effect of literacy group was found in the absence of a main effect for intelligence or an interaction between these factors. To assess the potential confounding effects of attention, a second analysis of the frequency discrimination data was conducted with performance on catch trials entered as a covariate. Significant effects for both the covariate and literacy skill was found, but again there was no main effect of intelligence, nor was there an interaction between intelligence and literacy skill. Regression analyses were conducted to determine the magnitude of the relationship between sensory and literacy skills in the entire sample. Both visual motion sensitivity and auditory sensitivity to frequency differences were robust predictors of children's literacy skills and their orthographic and phonological skills. Copyright © 2002 John Wiley & Sons, Ltd.
Operating properties of thin‐film slot antennas at 2.5‐THz submillimeter wave band
Authors: Abe Yasuhiko , Yasuoka Yoshizumi 
Published: October 2002

AbstractWith a view to the design and fabrication of slot array antennas operating in the submillimeter wave region above 2.5 THz, the operating characteristics of a thin‐film slot antenna on a dielectric substrate are studied with emphasis on the radiation pattern. It is found that unlike the thin‐film slot antenna in the frequency region below 700 GHz, the thin‐film slot antenna itself is likely to be operated at the free‐space wavelength, but the antenna is not that in free space and is influenced by the dielectric constant and absorption coefficient of the substrate and the substrate thickness. It is also found that the coplanar waveguide is operating at a mean wavelength derived from the average dielectric constant of free space and the dielectric substrate, like that in the frequency region below 700 GHz. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(11): 8–15, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10053
Effects of migration methods in parallel distributed parameter‐free genetic algorithm
Authors: Adachi Susumu , Sawai Hidefumi 
Published: October 2002

AbstractThe effects of migration in parallel distributed processing of a parameter‐free genetic algorithm (PfGA) that does not require establishing genetic parameters such as the initial population size, crossing‐over rate, and mutation rate are discussed. This PfGA is a compact and robust algorithm characterized by the fact that it extracts one local population (subpopulation) from the entire search space and searches the prospective space while varying the local population size adaptively. The algorithm has been implemented on parallel computers using a hierarchical parallel‐distributed architecture of the PfGA that includes migration methods. As a result of performance evaluation using a general functional optimization (minimum value search) problem including the international benchmark problem, it has been verified that the search success rate is maintained or improved, and that increasing the number of local populations by using the proposed migration selection methods can effectively reduce the number of evaluations required for success. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(11): 71–80, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10096
Improvement of MTTF of feedforward neural networks by applying relearning
Authors: Tohma Yoshihiro , Abe Munehiro 
Published: October 2002

AbstractMany neural networks have been studied, most of them using computer simulations, as a source of new computational paradigms. Since most implementations of neural networks require many elemental components, it is necessary to use a fault‐tolerance mechanism with them. This paper examines a hierarchical neural network in which recovery from a functional breakdown of the whole network (due to breakdown of its parts) can be performed by relearning. The repeated relearning significantly improves the time to failure of the whole network after a partial breakdown. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(11): 81–88, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10097