bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ermittlung der Tragfähigkeit und insbesondere der Belastbarkeit einer Spannbeton‐Straßenbrücke mittels Dynamischem Bauwerksmonitoring
Authors: Veit‐Egerer Robert , Wenzel Helmut 
Published: May 2008

AbstractBei der Straßenbrücke Komořany, Tschechien handelt es sich um eine 2‐spurige Querung einer mehrgleisigen Verbindung, die als Spannbetonbrücke ausgeführt ist. Das Haupttragwerk besteht aus zwei Feldern mit einer Gesamtlänge von rund 63 m. Im Hauptfeld ist dann ein aus neun vorgespannten Betonfertigteilen (I‐Träger) gefertigter Einhängeträger über zwei Gerbergelenke in das Brückentragwerk eingefügt. Diese Fertigteile werden quer zur Brückenachse über Zugstangen zusammengehalten, welche durch deren Ober‐ und Untergurte geführt werden, um eine kraftschlüssige Lastableitung als Gesamtquerschnitt zu gewährleisten. Gegenstand der vorliegenden Untersuchung ist eine dynamische Analyse an der Straßenbrücke Komořany mit BRIMOS®, wodurch der globale Erhaltungszustand des Tragwerks analysiert werden soll, wobei insbesondere die Tragfähigkeit bzw. die Belastbarkeit der Tragstruktur festgelegt und damit Empfehlungen für die weitere Betriebsdauer gegeben werden. Das Hauptaugenmerk liegt dabei auf dem Einhängeträger, der a priori sowohl global (Gerbergelenke) als auch lokal (Quervorspannung) besondere Aufmerksamkeit erfordert.
Modellbildung zur Simulation von Stahlfaserbeton unter hochdynamischer Belastung
Authors: Gebbeken Norbert , Greulich Stefan , Pietzsch Achim , Hartmann Thomas 
Published: May 2008

AbstractFür den baulichen Schutz vor außergewöhnlichen Beanspruchungen werden Werkstoffe mit problemangepassten Eigenschaften benötigt. Einer dieser Werkstoffe ist Stahlfaserbeton. Für hochdynamische Lasten aus Impakt oder Explosion ist der Werkstoff Stahlfaserbeton jedoch noch nicht hinreichend erforscht.Dieser Beitrag beschreibt ein neues, auf empirischen Zusammenhängen basierendes Materialmodell zur Simulation von Stahlfaserbeton mit unterschiedlichen Stahlfasergehalten unter hochdynamischer Beanspruchung. Es beinhaltet auch ein Schädigungsmodell, das die Verringerung der Steifigkeit und der Festigkeit des Stahlfaserbetons infolge plastischer Verformungen (Kompaktion und Gestaltänderung) beschreibt.Das Modell ist in eine Hydrocode‐Umgebung implementiert und wurde anhand einer Vielzahl von Ansprengversuchen validiert. Dabei konnte gezeigt werden, dass numerische Simulationen mit dem neuen Stahlfaserbetonmodell geeignet sind, aufwändige und teure Versuche zu ergänzen bzw. zu reduzieren.
Replicon‐free and markerless methods for genomic insertion of DNAs in phage attachment sites and controlled expression of chromosomal genes in Escherichia coli
Authors: Chiang Chung‐Jen , Chen Po Ting , Chao Yun‐Peng 
Published: May 2008

AbstractGenetic manipulation of cells for desired traits is the most appreciable strategy implemented in the field of bioengineering. However, this approach closely relies on the use of plasmids and is commonly afflicted by the potential problem of plasmid instability and safety caution. Meanwhile, it may also lead to the spread of antibiotic‐resistant markers with replicons of plasmids to the environment. However, this issue has long been neglected. In this study, we have addressed these subjects by developing replicon‐free and markerless methods for chromosomal insertion of genes and controlled expression of genomic genes in Escherichia coli. For the former application, the integration vectors of conditional replication were incorporated with the prophage attachment site and duplicated FRT sites. Their utility was illustrated by site‐specific insertion of target genes, the endogenous dxs gene and three heterologous genes consisting of gps, crtI, and crtB, fused to T7 promoter into E. coli genome. For the latter application, the template vectors for promoter replacement were constructed to carry a DNA cassette containing the T7 promoter linked to a selective marker flanked with the FRT site. Subsequently, it was illustrated by replacement of the native promoter of chromosomal pckA by the T7 promoter. Finally, with the aid of FLP recombinase supplied from a helper plasmid, the regions containing replicon and/or selective markers in inserted DNAs were eliminated from integrants for both approaches. As a consequence, the expression of these five genes was subject to control by one response regulator, T7 RNA polymerase, in a regulon way, resulting in a high and stable production of lycopene in the cell. This result indicates the promise of developed methods for genome engineering in E. coli. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Modeling of Xanthophyllomyces dendrorhous growth on glucose and overflow metabolism in batch and fed‐batch cultures for astaxanthin production
Authors: Liu Yuan‐Shuai , Wu Jian‐Yong 
Published: May 2008

AbstractAn astaxanthin‐producing yeast Xanthophyllomyces dendrorhous ENM5 was cultivated in a liquid medium containing 50 g/L glucose as the major carbon source in stirred fermentors (1.5‐L working volume) in fully aerobic conditions. Ethanol was produced during the exponential growth phase as a result of overflow metabolism or fermentative catabolism of glucose by yeast cells. After accumulating to a peak of 3.5 g/L, the ethanol was consumed by yeast cells as a carbon source when glucose in the culture was nearly exhausted. High initial glucose concentrations and ethanol accumulation in the culture had inhibitory effects on cell growth. Astaxanthin production was partially associated with cell growth. Based on these culture characteristics, we constructed a modified Monod kinetic model incorporating substrate (glucose) and product (ethanol) inhibition to describe the relationship of cell growth rate with glucose and ethanol concentrations. This kinetic model, coupled with the Luedeking–Piret equation for the astaxanthin production, gave satisfactory prediction of the biomass production, glucose consumption, ethanol formation and consumption, and astaxanthin production in batch cultures over 25–75 g/L glucose concentration ranges. The model was also applied to fed‐batch cultures to predict the optimum feeding scheme (feeding glucose and corn steep liquor) for astaxanthin production, leading to a high volumetric yield (28.6 mg/L) and a high productivity (5.36 mg/L/day). © 2008 Wiley Periodicals, Inc.
Silent mutations result in HlyA hypersecretion by reducing intracellular HlyA protein aggregates
Authors: Gupta Prateek , Lee Kelvin H. 
Published: May 2008

AbstractEscherichia coli is one of the most widely used hosts for the production of recombinant proteins. Extracellular protein secretion has the advantage of reducing protein aggregation and simplifying downstream purification. The introduction of five rare codons in a specific region of the α‐hemolysin (hlyA) gene previously was shown to result in eightfold improvement in secretion of HlyA via the hemolysin (Type‐I) pathway. Here we investigate the biological basis for the observed phenomenon that translation rate of HlyA protein may be related to the ability to secrete higher levels of HlyA via the Type‐I pathway. A detailed comparative analysis between a hypersecreter mutant strain (hly‐slow) and a control strain (hly‐parent) shows a significant decrease (by ∼50%) in the intracellular level of HlyA protein in the hly‐slow strain relative to the hly‐parent strain. Nearly 100% of the intracellular HlyA protein exists in the inclusion body fraction in both the strains. These results demonstrate the importance of synonymous codon changes in the context of improving HlyA secretion yield via Type‐I pathway and further illustrate that production of high levels of secreted proteins appears to require a balance between translation and secretion rate. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Cell inactivation and membrane damage after long‐term treatments at sub‐zero temperature in the supercooled and frozen states
Authors: Moussa Marwen , Dumont Frédéric , Perrier‐Cornet Jean‐Marie , Gervais Patrick 
Published: May 2008

AbstractThe survival of cells subjected to cooling at sub‐zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze‐thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of cells subjected to cold stress, through long‐term supercooling experiments, versus freeze‐thawing stress. The viability of Escherichia coli, Saccharomyces cerevisiae, and leukemia cells were assessed over time. Supercooled conditions were maintained for 71 days at −10°C, and for 4 h at −15°C, and −20°C, without additives or emulsification. Results showed that cells could be inactivated by the only action of sub‐zero temperature, that is, without any water crystallization. The loss of cell viability upon exposure to sub‐zero temperatures is suggested to be caused by exposure to cold shock which induced membrane damage. During holding time in the supercooled state, elevated membrane permeability results in uncontrolled mass transfer to and from the cell maintained at cold conditions and thus leads to a loss of viability. With water crystallization, cells shrink suddenly and thus are exposed to cold osmotic shock, which is suggested to induce abrupt loss of cell viability. During holding time in the frozen state, cells remain suspended in the residual unfrozen fraction of the liquid and are exposed to cold stress that would cause membrane damage and loss of viability over time. However, the severity of such a stress seems to be moderated by the cell type and the increased solute concentration in the unfrozen fraction of the cell suspension. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Evaluation of CO2‐based cold sterilization of a model hydrogel
Authors: Jiménez A. , Zhang J. , Matthews M.A. 
Published: May 2008

AbstractThe purpose of the present work is to evaluate a novel CO2‐based cold sterilization process in terms of both its killing efficiency and its effects on the physical properties of a model hydrogel, poly(acrylic acid‐co‐acrylamide) potassium salt. Suspensions of Staphylococcus aureus and Escherichia coli were prepared for hydration and inoculation of the gel. The hydrogels were treated with supercritical CO2 (40°C, 27.6 MPa). The amount of bacteria was quantified before and after treatment. With pure CO2, complete killing of S. aureus and E. coli was achieved for treatment times as low as 60 min. After treatment with CO2 plus trace amounts of H2O2 at the same experimental conditions, complete bacteria kill was also achieved. For times less than 30 min, incomplete kill was noted. Several physical properties of the gel were evaluated before and after SC‐CO2 treatment. These were largely unaffected by the CO2 process. Drying curves showed no significant change between treated (pure CO2 and CO2 plus 30% H2O2) and untreated samples. The average equilibrium swelling ratios were also very similar. No changes in the dry hydrogel particle structure were evident from SEM micrographs. Biotechnol. Bioeng. 2008;101: 1344–1352. © 2008 Wiley Periodicals, Inc.
Preparation of human immune effector T cells containing iron‐oxide nanoparticles
Authors: Iida Hironori , Takayanagi Kosuke , Nakanishi Takuya , Kume Akiko , Muramatsu Kouji , Kiyohara Yoshio , Akiyama Yasuto , Osaka Tetsuya 
Published: May 2008

AbstractPreparation of human immune T cells containing iron‐oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen‐specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor‐specific CTLs containing magnetic nanoparticles. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
A population analysis of VEGF transgene expression and secretion
Authors: Karoubi Golnaz , Stewart Duncan J. , Courtman David W. 
Published: May 2008

AbstractThe induction of therapeutic angiogenesis with gene therapy approaches has received considerable interest and some limited clinical success. A major drawback to this approach is a lack of understanding of the pharmacokinetics of therapeutic protein delivery. This has become increasingly more relevant as recent studies have illustrated a defined therapeutic window for angiogenic protein secretion into the local microenvironment. For cell based gene therapies, with cells widely distributed throughout the tissue, this implies that any individual cell must attain a specific secretion rate to produce a local angiogenic response. Here we report a reproducible technique enabling the study of growth factor secretion from individual cells following transient plasmid transfection. We demonstrate significant variability in single cell vascular endothelial growth factor (VEGF) secretion with the majority of total protein secretion arising from a small subpopulation of transfected cells. We demonstrate that VEGF secretion is linearly correlated to intracellular plasmid copy number and protein secretion does not appear to reach saturation within the cell population. The selection of gene therapy approaches that optimize individual cell secretion profiles may be essential for the development of effective gene therapies. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Catabolic pathways and cellular responses of Pseudomonas putida P8 during growth on benzoate with a proteomics approach
Authors: Cao Bin , Loh Kai‐Chee 
Published: May 2008

AbstractThe catabolic pathways and cellular responses of Pseudomonas putida P8 during growth on benzoate were studied through proteomics approach. Two‐dimensional gel electrophoresis (2‐DE) gel profiles of P. putida cells grown on 100 and 800 mg/L benzoate were quantitatively compared using threshold criteria and statistical tools. Protein spots of interest were identified through database searching based on peptide mass fingerprints (PMFs) obtained using matrix assisted laser desorption/ionization‐time of flight mass spectrometry (MALDI‐TOF MS). Eight catabolic enzymes involved in both the ortho‐cleavage (CatB, PcaI, and PcaF) and the meta‐cleavage (DmpC, DmpD, DmpE, DmpF, and DmpG) pathways for benzoate biodegradation were identified in P. putida grown on 800 mg/L of benzoate while no meta‐cleavage pathway enzymes were observed in the 2‐DE gel profiles of P. putida grown on 100 mg/L of benzoate. The activation of both the ortho‐ and the meta‐cleavage pathways in P. putida P8 grown on high benzoate concentration was confirmed directly at the protein level. In addition, another 28 differentially expressed proteins were also identified, including proteins involved in (i) detoxification and stress response (AhpC, ATPase‐like ATP‐binding region, putative DNA‐binding stress protein, SodB and catalase/peroxidase HPI); (ii) carbohydrate, amino acid/protein and energy metabolism (isocitrate dehydrogenase, SucC, SucD, AcnB, GabD, ArcA, ArgI, Efp and periplasmic binding proteins of several ABC‐transporters); and (iii) cell envelope and cell division (bacterial surface antigen family protein and MinD). Based on the data obtained, physiological changes of P. putida in response to growth on benzoate at different concentrations were discussed. Biotechnol. Bioeng. 2008;101: 1297–1312. © 2008 Wiley Periodicals, Inc.
Market mavenism and consumer self‐confidence
Authors: Clark Ronald A. , Goldsmith Ronald E. , Goldsmith Elizabeth B. 
Published: May 2008

Abstract

The purpose of this study was to test hypothesized associations between market mavenism and consumer self‐confidence (CSC). A survey of 190 US consumers provided the data. The results showed significant relationships between mavenism and several dimensions of CSC, and regression analysis emphasized the relationships with two of these: information acquisition (confidence in the ability to obtain and use marketplace information) and social outcomes decision making (confidence in obtaining positive reactions from others). These findings both enrich our knowledge of the psychology of market mavenism by suggesting some motivations for these behaviors and suggest marketing strategies can be fine‐tuned to appeal more effectively to this important segment of consumers.
Copyright © 2008 John Wiley & Sons, Ltd.
Effect of concanavalin A (Con‐A) on the hormone production of the unicellular Tetrahymena and the immune cells of the rat. A comparative study
Authors: Csaba György , Pállinger Éva 
Published: May 2008

AbstractTetrahymena populations were treated with 10−15 g ml−1 or 10−6 g ml−1 concanavalin‐A (Con‐A) in tryptone‐yeast medium for 1 h. Rat peritoneal immune cells (mast cells, lymphocytes, monocyte‐granulocyte group) were also treated with 10−6 g ml−1 Con‐A, for 1 h. The cells' hormone (ACTH, histamine, serotonin, endorphin, triiodothyronine (T3)) content was measured by using immunocytochemistry and flow cytometry. The extremely low dose of Con‐A universally and significantly elevated the hormone contents, while the result of higher dose was uncertain. In the immune cells, Con‐A significantly decreased the ACTH level in each cell type and histamine level in mast cells. The results demonstrate the very high sensitivity of Tetrahymena receptors for a non‐hormone (lectin) molecule, which can bind to the insulin receptors and mimics the effect of insulin. The results also show that Tetrahymena receptors are more sensitive to lower concentrations of molecules than to higher ones. The universal hormone‐production stimulating effect of Con‐A—which is observed in Tetrahymena—is specified in rat. Copyright © 2008 John Wiley & Sons, Ltd.
Mitochondria as the target for mildronate's protective effects in azidothymidine (AZT)‐induced toxicity of isolated rat liver mitochondria
Authors: Pupure Jolanta , Fernandes Maria A. S. , Santos Maria S. , Moreno António J. M. , Kalvinsh Ivars , Klusa Vija , Oliveira Catarina R. 
Published: May 2008

AbstractPreviously mildronate, an aza‐butyrobetaine derivative, was shown to be a cytoprotective drug, through its mechanism of action of inhibition of carnitine palmitoyltransferase‐1, thus protecting mitochondria from long‐chain fatty acid accumulation and subsequent damage. Recently in an azidothymidine (AZT)‐induced cardiotoxicity model in vivo (in mice), we have found mildronate's ability of protecting heart tissue from nuclear factor κB abnormal expression. Preliminary data also demonstrate cerebro‐ and hepatoprotecting properties of mildronate in AZT‐toxicity models. We suggest that mildronate may target its action predominantly to mitochondria. The present study in isolated rat liver mitochondria was designed to clarify mitochondrial targets for mildronate by using AZT as a model compound. The aim of this study was to investigate: (1) whether mildronate may protect mitochondria from AZT‐induced toxicity; and (2) which is the most critical target in mitochondrial processes that is responsible for mildronate's regulatory action. The results showed that mildronate protected mitochondria from AZT‐induced damage predominantly at the level of complex I, mainly by reducing hydrogen peroxide generation. Significant protection of AZT‐caused inhibition of uncoupled respiration, ADP to oxygen ratio, and transmembrane potential were also observed. Mildronate per se had no effect on the bioenergetics, oxidative stress, or permeability transition of rat liver mitochondria. Since mitochondrial complex I is the first enzyme of the respiratory electron transport chain and its damage is considered to be responsible for different mitochondrial diseases, we may account for mildronate's effectiveness in the prevention of pathologies associated with mitochondrial dysfunctions. Copyright © 2008 John Wiley & Sons, Ltd.
In vitro effects of 2‐methoxyestradiol on MCF‐12A and MCF‐7 cell growth, morphology and mitotic spindle formation
Authors: Van Zijl Catherina , Lottering Mona‐Liza , Steffens Francois , Joubert Annie 
Published: May 2008

AbstractThe influence of 2‐methoxyestradiol (2ME) was investigated on cell growth, morphology and spindle formation in a tumorigenic (MCF‐7) and non‐tumorigenic (MCF‐12A) epithelial breast cell line. Inhibition of cell growth was more pronounced in the MCF‐7 cells compared to the MCF‐12A cells following 2ME treatment. Dose‐dependent studies (10−5 – 10−9 M) revealed that 10−6 M 2ME inhibited cell growth by 44% in MCF‐12A cells and by 84% in MCF‐7 cells (p‐value < 0.05). 2ME‐treated MCF‐7 cells showed abnormal metaphase cells, membrane blebbing, apoptotic cells and disrupted spindle formation. These observations were either absent or less prominent in MCF‐12A cells. 2ME had no effect on the length of the cell cycle between S‐phase and the time a mitotic peak was reached in either cell line but MCF‐7 cells were blocked in mitosis with no statistically significant alterations in the phosphorylation status of Cdc25C. Nevertheless, Cdc2 activity was significantly increased in MCF‐7 cells compared to MCF‐12A cells (p‐value < 0.05). The results indicate that 2ME disrupts mitotic spindle formation and enhances Cdc2 kinase activity, leading to persistence of the spindle checkpoint and thus prolonged metaphase arrest that may result in the induction of apoptosis. The tumorigenic MCF‐7 cells were especially sensitive to 2ME treatment compared to the normal MCF‐12A cells. Therefore, differential mechanism(s) of growth inhibition are evident between the normal and tumorigenic cells. Copyright © 2008 John Wiley & Sons, Ltd.
Membranadsorbersysteme in der Proteinaufreinigung: Screening‐Möglichkeiten
Authors: Kökpinar Ö. , Walter J.‐G. , Anton F. , Mönster A. , Kasper C. , Stahl F. , Scheper T. 
Published: May 2008

AbstractUnterschiedlich funktionalisierte Membranen (Membranen für Ionenaustausch‐, Affinitäts‐ und Metallchelatchromatographie) wurden auf ihr Bindungs‐ bzw. Elutionsverhalten und auf ihre Eignung zur Isolierung und Reinigung von Modellproteinen aus einem Gemisch sowie aus Kulturüberständen und Zelllysaten untersucht. Hierzu werden zwei verschiedene Membranadsorbereinheiten als Screening‐Module verwendet, die das Arbeiten im Mikrolitermaßstab vereinfachen: spin columns und 8‐strips.
Industrielle Biotechnologie: Wirtschaftspolitische Bedeutung, Wettbewerbsfähigkeit und Standortattraktivität Deutschlands
Authors: Nusser M. 
Published: May 2008

AbstractDeutschland ist in der industriellen Biotechnologie im internationalen Wettbewerb sehr gut positioniert. Zwar gibt es Schwächen und Risiken (z. B. unzureichende Politikkoordination und Verfügbarkeit von Risikokapital, zu wenige Demonstrationsanlagen, zukünftige Engpässe beim qualifizierten Personal), jedoch ergeben sich auf Grund der Stärken (u. a. starke technologische Wissensbasis, gut ausgebildete Arbeitskräfte, wettbewerbsfähige industrielle Basis in wichtigen Anwenderbranchen mit Zugang zu großen Exportmärkten) zukünftig enorme Innovations‐, Wachstums‐ und Beschäftigungspotenziale.