bluuebunny/crossref_metadata_2025_split huggingface dataset:
Caspases and Neuronal Development
Authors: Ryan C. A. , Salvesen G. S. 
Published: September 2004

AbstractRecent developments have shown that inappropriate activation of apoptotic pathways contributes to many neurodegenerative diseases. The basic mechanisms that underlie apoptosis in neurodegenerative diseases are uncertain, although they likely represent the subversion of normal developmental programs. Several types of neuronal cell death have been reported, including autophagic and caspase-independent cell death. In this review we consider evidence for the participation of apoptotic caspases in neuronal development, and examine the hypothesis that differentiating neurons undergo stage-specific alterations in apoptosis sensitivity that may be due to caspase regulation. In addition, we present data supporting this hypothesis.
Procongopain from Trypanosoma congolense Is Processed at Basic pH: An Unusual Feature among Cathepsin L-Like Cysteine Proteases
Authors: Serveau C. , Boulangé A. , Lecaille F. , Gauthier F. , Authié E. , Lalmanach G. 
Published: September 2004

AbstractCongopain, the major cysteine protease from Trypanosoma congolense, is synthesized as an inactive zymogen, and further converted into its active form after removal of the proregion, most probably via an autocatalytic mechanism. Processing of recombinant procongopain occurs via an apparent one-step or a multistep mechanism depending on the ionic strength. The auto-activation is pH-dependent, with an optimum at pH 4.0, and no activation observed at pH 6.0. After addition of dextran sulfate (10 ug/ml), an approx. 20-fold increase of processing (expressed as enzymatic activity) is observed. Furthermore, in the presence of dextran sulfate, procongopain can be processed at pH 8.0, an unusual feature among papainlike enzymes. Detection of procongopain and trypanosomal enzymatic activity in the plasma of T. congolenseinfected cattle, together with the capacity of procongopain to be activated at weakly basic pH, suggest that procongopain may be extracellularly processed in the presence of blood vessel glycosaminoglycans, supporting the hypothesis that congopain acts as a pathogenic factor in host-parasite relationships.
Heat Stress-Dependent DNA Binding of Arabidopsis Heat Shock Transcription Factor HSF1 to Heat Shock Gene Promoters in Arabidopsis Suspension Culture Cells in vivo
Authors: Zhang L. , Lohmann C. , Prändl R. , Schöffl F. 
Published: September 2004

AbstractUsing UV laser cross-linking and immunoprecipitation we measured the in vivo binding of Arabidopsis heat shock transcription factor HSF1 to the promoters of target genes, Hsp18.2 and Hsp70. The amplification of promoter sequences, co-precipitated with HSF1-specific antibodies, indicated that HSF1 is not bound in the absence of heat stress. Binding to promoter sequences of target genes is rapidly induced by heat stress, continues throughout the heat treatment, and declines during subsequent recovery at room temperature. The molecular mechanisms underlying the differences between Hsp18.2 and Hsp70 in the kinetics of HSF1/promoter binding and corresponding mRNA expression profiles are discussed.
Interaction of Maize Chromatin-Associated HMG Proteins with Mononucleosomes: Role of Core and Linker Histones
Authors: Lichota J. , Grasser K. D. 
Published: September 2004

AbstractTwo groups of plant chromatin-associated high mobility group (HMG) proteins, namely the HMGA family, typically containing four A/T-hook DNA-binding motifs, and the HMGB family, containing a single HMG-box DNA-binding domain, have been identified. We have examined the interaction of recombinant maize HMGA and five different HMGB proteins with mononucleosomes (containing approx. 165 bp of DNA) purified from micrococcal nuclease-digested maize chromatin. The HMGB proteins interacted with the nucleosomes independent of the presence of the linker histone H1, while the binding of HMGA in the presence of H1 differed from that observed in the absence of H1. HMGA and the HMGB proteins bound H1-containing nucleosome particles with similar affinity. The plant HMG proteins could also bind nucleosomes that were briefly treated with trypsin (removing the N-terminal domains of the core histones), suggesting that the histone N-termini are dispensable for HMG protein binding. In the presence of untreated nucleosomes and trypsinised nucleosomes, HMGB1 could be chemically crosslinked with a core histone, which indicates that the trypsin-resistant part of the histones within the nucleosome is the main interaction partner of HMGB1 rather than the histone N-termini. In conclusion, these results indicate that specific nucleosome binding of the plant HMGB proteins requires simultaneous DNA and histone contacts.
Physarum polycephalum Expresses a Dihydropteridine Reductase with Selectivity for Pterin Substrates with a 6-(1', 2-Dihydroxypropyl) Substitution
Authors: Wild C. , Golderer G. , Gröbner P. , Werner-Felmayer G. , Werner E. R. 
Published: September 2004

AbstractPhysarum polycephalum is one of few non-animal organisms capable of synthesizing tetrahydrobiopterin from GTP. Here we demonstrate developmentally regulated expression of quinoid dihydropteridine reductase (EC 1.6.99.7), an enzyme required for recycling 6,7-[8H]-dihydrobiopterin. Physarum also expresses phenylalanine-4-hydroxylase activity, an enzyme that depends on dihydropteridine reductase. The 24.4 kDa Physarum dihydropteridine reductase shares 43% amino acid identity with the human protein. A number of residues important for function of the mammalian enzyme are also conserved in the Physarum sequence. In comparison to sheep liver dihydropteridine reductase, purified recombinant Physarum dihydropteridine reductase prefers pterin substrates with a 6-(1', 2'-dihydroxypropyl) group. Our results demonstrate that Physarum synthesizes, utilizes and metabolizes tetrahydrobiopterin in a way hitherto thought to be restricted to the animal kingdom.
Inhibition of Intraperitoneal Tumor Growth of Human Ovarian Cancer Cells by Bi- and Trifunctional Inhibitors of Tumor-Associated Proteolytic Systems
Authors: Krol J. , Kopitz C. , Kirschenhofer A. , Schmitt M. , Magdolen U. , Krüger A. , Magdolen V. 
Published: September 2004

AbstractSeveral proteolytic systems are involved in (anti)adhesive, migratory, and proteolytic processes, necessary for tumor progression and metastasis. We analyzed whether multifunctional inhibitors of different tumor-associated proteolytic systems reduce tumor growth and spread of human ovarian cancer cells in vivo. Bifunctional inhibitors are composed of the N-terminal domain of either the human matrix metalloproteinase inhibitors TIMP-1 or TIMP-3 and the cysteine protease inhibitor chicken cystatin (chCysWT); trifunctional inhibitors are composed of N-TIMP-1 or -3 and a chicken cystatin variant harboring the uPAR binding site of uPA, chCys-uPA19-31, which in addition to its inhibitory activity toward cysteine proteases interferes with the interaction of the serine protease uPA with its receptor. OV-MZ-6#8 cancer cells, stably transfected with plasmids expressing the multifunctional inhibitors, displayed similar proliferative and adhesive features as the vector-transfected control, but showed significant reduction in their invasive behavior in vitro. The cell lines expressing the multifunctional inhibitors were inoculated into the peritoneum of nude mice. Expression of three of the four inhibitor variants (NhTIMP-1-chCysWT, N-hTIMP-1- chCys-uPA19-31, and N-hTIMP-3-chCysWT) resulted in a significant reduction of tumor burden compared to the vector-control cell line. These compact and small inhibitors may represent promising agents for gene therapy of solid malignant tumors.
Assignment of Disulphide Bridges in Par j 2.0101, a Major Allergen of Parietaria judaica Pollen
Authors: Amoresano A. , Pucci P. , Duro G. , Colombo P. , Costa M. A. , Izzo V. , Lamba D. , Geraci D. 
Published: September 2004

AbstractPar j 2.0101, a major allergen of the Parietaria judaica pollen, was expressed in E. coli, purified to homogeneity and fully characterised both at the structural and the functional level. The recombinant rPar j 2.0101 protein showed an allergenic activity in histamine release, skin prick tests and capacity to bind IgE, almost identical to that of the native allergens purified from aqueous pollen extract. The complete pattern of S-S bridges of rPar j 2.0101 was determined by enzymatic digestion with endoproteinase Lys-C followed by mass spectrometric analysis of the resulting peptide mixtures. The eight cysteines occurring in the allergenic protein were found to be paired into the following four disulphides: Cys35-Cys83, Cys45- Cys60, Cys61-Cys106 and Cys81-Cys121. This structural information probes Par j 2.0101 to attain a 3-D fold consistent with that of the nonspecific lipid transfer protein (ns-LTP) family and it represents an effective molecular basis to develop modified antigens by selective site-directed mutagenesis for immunotherapy.
The Activator-Binding Site of Onchocerca volvulus S-Adenosylmethionine Decarboxylase, a Potential Drug Target
Authors: Ndjonka D. , Zou Y. , Bi X. , Woster P. , Walter R. D. , Lüersen K. 
Published: September 2004

AbstractS-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. In many eukaryotes its activity is stimulated specifically by putrescine. The AdoMetDC of the filarial parasite Onchocerca volvulus, however, is not only stimulated by putrescine but also by the naturally occuring polyamines spermidine and spermine. Several diamines, acetylated polyamines and polyamine analogues were used to analyse what molecular prerequisites are needed to stimulate nematode AdoMetDC activity. In the absence of an activator, the O. volvulus enzyme exhibits an extremely low specific activity. This fact, together with the unspecificity of activator binding, was thought to be useful for a new strategy to inhibit nematode AdoMetDC activity. Therefore, different polyamine analogues were tested as competitive inhibitors towards the stimulatory effect putrescine has on the O. volvulus and, in comparison, on the Caenorhabditis elegans and human AdoMetDC. Bis(aralkyl)- and bis(alkyl)-substituted polyamine analogues with a 3-7-3 backbone were found to inhibit AdoMetDC activities, however, probably without interfering with the putrescine stimulation. The best inhibitor, BW-1, was about 10-fold more effective against O. volvulus AdoMetDC than against the human enzyme. Unexpectedly, BW-1 was determined to be a competitive inhibitor with respect to AdoMet, having a Ki value of 310 uM for the putrescine-stimulated human AdoMetDC. Furthermore, we show for the O. volvulus and the human enzyme that the degree of inhibition by BW-1 depends on the actual putrescine concentration.
Clinical Relevance of Matrix Metalloproteinase-13 Determined with a New Highly Specific and Sensitive ELISA in Ascitic Fluid of Advanced Ovarian Carcinoma Patients
Authors: Hantke B. , Harbeck N. , Schmalfeldt B. , Claes I. , Hiller O. , Luther M.-O. , Welk A. , Kuhn W. , Schmitt M. , Tschesche H. , Muehlenweg B. 
Published: September 2004

AbstractMatrix metalloproteinases (MMPs) are involved in many physiological and pathophysiological processes, including tumor cell invasion and metastasis. For one member of this family, MMP-13 (collagenase-3), a new, highly specific ELISA with a sensitivity of 0.5 ng MMP-13/ml was established. The protein levels of MMP-13 in ascitic fluids of 30 patients with advanced ovarian cancer FIGO stage III (n=19) and IV (n=11) were measured with this ELISA. Using a cutoff value of 0.5 ng MMP-13/mg total protein, two patient subpopulations with short (median 16 months) and long (median 36 months) overall survival were identified. Together with other prognostic markers, determination of MMP-13 in ascitic fluid may help to identify patients at risk for early death and help to individualize adjuvant therapy.
Anti-Mouse GPI-PLD Antisera Highlight Structural Differences between Murine and Bovine GPI-PLDs
Authors: Gregory P. , Ziemiecki A. , Zürcher G. , Brodbeck U. , Bütikofer P. 
Published: September 2004

AbstractDespite its well characterised biochemistry, the physiological role of glycosylphosphatidylinositolspecific phospholipase D (GPIPLD) is unknown. Most of the previous studies investigating the distribution of GPI-PLD have focused on the human and bovine forms of the enzyme. Studies on mouse GPI-PLD are rare, partly due to the lack of a specific antimouse GPI-PLD antibody, but also due to the apparent low reactivity of existing antibodies to rodent GPI-PLDs. Here we describe the isolation of a mouse liver cDNA, the construction and expression of a recombinant enzyme and the generation of an affinitypurified rabbit antimouse GPI-PLD antiserum. The antibody shows good reactivity to partially purified murine and purified bovine GPI-PLD. In contrast, a rat antibovine GPI-PLD antibody shows no reactivity with the mouse enzyme and the two antibodies recognise different proteolytic fragments of the bovine enzyme. Comparison between the rodent, bovine and human enzymes indicates that small changes in the amino acid sequence of a short peptide in the mouse and bovine GPI-PLDs may contribute to the different reactivities of the two antisera. We discuss the implications of these results and stress the importance of antibody selection while investigating GPI-PLD in the mouse.
Optimization of a Violin Top with a Combined Laminate Theory and Honeycomb Model of Wood
Authors: Carlsson P. , Tinnsten M. 
Published: September 2004

Summary
Stochastic optimization with the simulated annealing method (SA) is performed on a violin top
made of Norway spruce (Picea Abies). A numerical example is presented which shows that it is
possible, through changes in thickness variables, to compensate for changes in vibration properties
caused by a variation in the material parameters in the top. A material model is also presented for
the blank which considers the influence of density variations in the annual rings, the cellular structure
of wood and reinforcement from the wood rays.
Oxidized Derivatives of Lipophilic Extractives Formed during Hardwood Kraft Pulp Bleaching
Authors: Freire C. S. R. , Silvestre A. J. D. , Neto C. Pascoal 
Published: September 2004

Summary
The structural changes of E. globulus wood extractives during bleaching with chlorine dioxide (D),
oxygen (O), ozone (Z) and hydrogen peroxide (P) were studied. The detailed characterisation of
the extractive derivatives detected in the partially bleached D, O, P and Z pulps was achieved by
performing reactions of pure reference compounds with the different bleaching agents. The results
show that the unsaturated sterols and fatty acids are extensively degraded during chlorine dioxide
and ozone bleaching and only partially degraded during oxygen and hydrogen peroxide bleaching.
The corresponding saturated extractives as well as the long chain aliphatic alcohols and ω-hydroxyfatty
acids were stable during bleaching. The main oxidation products of β-sitosterol and oleic
and linoleic acids, including one chlorinated derivative of linoleic acid, were identified here for the
first time in E. globulus bleached pulps and bleaching filtrates.
Entwurf einer flachheitsbasierten Vorsteuerung für die induktive Erwärmung beim Thixoforming (Flatness Based Control of the Inductive Heating for Thixoforming)
Authors: Fleck Christian , Schönbohm Alexander 
Published: September 2004

Abstract
Thixoforming ist ein neuartiges Formgebungsverfahren, das es im Vergleich zu klassischen Formgebungsverfahren ermöglicht, Bauteile mit höheren Festigkeitswerten und komplexeren Bauformen zu fertigen. Dazu wird die Werkstofflegierung in einem teilflüssigen Zustand verarbeitet, d. h. das Werkstück wird so erwärmt, dass es sich innerhalb des Liquidus-Solidus-Intervalls seiner Legierung befindet und der Werkstoff teilweise aufschmilzt. Die Erwärmung muss möglichst schnell erfolgen, ohne dabei die Randbereiche des Werkstücks zu überhitzen. Da im industriellen Einsatz, in Ermangelung einer geeigneten Temperaturmesstechnik, gesteuerte Anlagen überwiegen, wird in diesem Beitrag eine Methode vorgestellt, die auf der Theorie der Flachheit von Systemen mit verteilten Parametern basiert und mit der geeignete Steuertrajektorien für die induktive Erwärmung von Aluminiumbolzen berechnet werden können. Dazu wird zunächst die das System beschreibende partielle Differentialgleichung vorgestellt und davon ausgehend ein flacher Ausgang des Systems im Zeitbereich bestimmt. Mithilfe des flachen Ausgangs wird eine geeignete Steuertrajektorie für die Stellgröße des Systems berechnet, mittels derer die Temperatur der Billetmitte einem gegebenen Zeitverlauf folgt. Anhand von numerischen Simulationen wird der Erfolg der vorgestellten Methode diskutiert.
Flachheitsbasierte Steuerung und Regelung eines Wärmeleitungssystems (Flatness-based Feedforward and Feedback Control of a Heat Conduction System)
Authors: Meurer Thomas , Zeitz Michael 
Published: September 2004

Abstract
Das lineare Modell eines örtlich eindimensionalen Wärmeleiters wird als Beispiel verwendet, um die flachheitsbasierte Steuerung und Regelung von parabolischen Systemen mit verteilten Parametern zu erläutern. Das betrachtete Wärmeleitermodell mit Randeingriff erlaubt den flachheitsbasierten Entwurf einer Steuerung mithilfe des inversen Systems, um eine hinreichend glatte Trajektorie des Ausgangs zu realisieren. Ein neues Verfahren zum Regler- und Beobachterentwurf ermöglicht die durchgängige flachheitsbasierte Synthese einer Folgeregelung mit Vorsteuerung und Zustandsschätzung. Dies wird beispielhaft für die Steuerung und Regelung des Übergangs zwischen stationären Temperaturprofilen gezeigt und anhand von Simulationsergebnissen diskutiert.
Eine neue Methode zur Regelung von Strecken mit Stellbegrenzung (A New Method for the Control of Systems with Input Saturation)
Authors: Hippe Peter 
Published: September 2004

Abstract
In einem gut gedämpft ausgelegten linearen Regelkreis kann sich eine Stellbegrenzung destabilisierend auswirken. Dieses Phänomen wird üblicherweise als Windup bezeichnet. Fast alle bisher bekannten Windup-Vermeidungsmaßnahmen treten erst dann in Aktion, wenn das Stellsignal den Begrenzungswert das erste Mal überschreitet. Obwohl dies bei stabilen Regelstrecken unproblematisch ist, hat es bei instabilen Systemen unter Umständen zur Konsequenz, dass sich mit solchen Maßnahmen eine Destabilisierung des Regelkreises nicht verhindern lässt. In diesem Beitrag wird nun ein neues Verfahren zur Vermeidung von Windup vorgestellt, das auf einer Trennung zwischen Führungsgrößen-Aufschaltung und Störausregelung beruht. Dadurch gelingt es, einen Teil des begrenzten Stellsignal-Bereiches für die Störbeseitigung und den verbleibenden Teil für das Führungsverhalten zu reservieren. Dies erlaubt die Auslegung von Regelungen mit gesicherter Stabilität bei exponentiell instabilen Regelstrecken mit Stellsignalbegrenzung und es ist gleichermaßen auch bei stabilen Strecken einsetzbar. Anhand der Regelung eines instabilen Systems wird die Anwendung des neuen Verfahrens demonstriert.
Geometrischer Zugang zur Polzuweisbarkeit mittels konstanter Ausgangsrückführungen (Geometric Approach to Pole Assignability by Means of Static Output Feedback)
Authors: Reinschke Kurt J. , Fritsche Oliver 
Published: September 2004

Abstract
Dieser Beitrag behandelt die beliebige Polzuweisbarkeit mithilfe statischer Ausgangsrückführungen bei linearen zeitinvarianten MIMO-Übertragungssystemen. Durch Nutzung von Ergebnissen aus der algebraischen Geometrie können Bedingungen für beliebige Polzuweisbarkeit abgeleitet werden. Alle zulässigen statischen Rückführungen lassen sich als Punkte in einer Grassmannschen Mannigfaltigkeit in einem projektiven Raum deuten. Unter der Annahme, dass das Produkt der Anzahl der skalaren Ein- und Ausgänge größer als die dynamische Ordnung des Systems ist, werden eine notwendige und eine hinreichende Bedingung für die beliebige Polzuweisbarkeit formuliert und bewiesen. Die Verfasser stellen ein Verfahren zur numerischen Ermittlung einer konstanten Ausgangsrückführmatrix vor, die die gewünschte Polplatzierung bewirkt. Anhand eines nicht-trivialen Beispiels werden die Rechenschritte des Verfahrens im Detail illustriert.
H
∞-Regelung von zeitdiskreten Deskriptorsystemen (H
∞ Control of Discrete-Time Descriptor Systems)
Authors: Rehm Ansgar , Allgöwer Frank 
Published: September 2004

Abstract
Die vorliegende Arbeit stellt einen theoretischen Beitrag zur H
∞-Regelung von zeitdiskreten Deskriptorsystemen dar. Es wird das Problem betrachtet, ein gesteuertes zeitdiskretes Deskriptorsystem durch statische Rückführung des Deskriptorvektors zu stabilisieren und gleichzeitig sicherzustellen, dass der geschlossene Regelkreis kausal ist und einer vorgegebenen H
∞-Normbeschränkung genügt. Der vorgestellte Zugang zu diesem Problem basiert auf einer Charakterisierung von stabilen, kausalen und H
∞-normbeschränkten Deskriptorsystemen mithilfe von linearen Matrixungleichungen (LMIs). Die zugeordnete Matrixvariable ist eng mit der Ljapunowfunktion des gegebenen Deskriptorsystems verknüpft. Angewandt auf den Fall des Regelungsproblems liefert dieses Resultat nichtlineare Matrixungleichungen, die zusätzlich zur Ljapunowmatrix noch die Rückführmatrix als unbekannte Matrixvariable enthalten. In dieser Arbeit wird ein Verfahren entwickelt, das es erlaubt, diese nichtlinearen Matrixungleichungen auf LMIs zurückzuführen, und sie damit einer effektiven numerischen Behandlung zugänglich macht.
Formale Methoden für implizite dynamische Systeme (A Formal Approach for Implicit Dynamic Systems)
Authors: Schlacher Kurt , Zehetleitner Kurt 
Published: September 2004

Abstract
Die Modellierung komplexer dynamischer Systeme führt oft auf Sätze von algebraischen Gleichungen und gewöhnlichen Differentialgleichungen. Dieser Beitrag präsentiert nun Methoden für implizite Systeme basierend auf der formalen Theorie von gewöhnlichen Differentialgleichungen. Es wird gezeigt, dass gewisse implizite Systeme, man nennt sie formal integrable, Eigenschaften aufweisen, die viele Untersuchungen ohne Überführung in eine explizite Form gestatten. Dabei wird ein dynamisches System als eine Untermannigfaltigkeit mit einer speziellen geometrischen Struktur aufgefasst. Die Form der Gleichungen entspricht dann lediglich einer speziellen Parametrierung dieser Untermannigfaltigkeit. Da man unter gewissen Regularitätsannahmen jedes implizite System in ein formal integrables überführen kann, stellt diese Klasse ein natürliches Bindeglied zwischen den expliziten und den impliziten Systemen dar. Auf Basis dieser Betrachtung werden zuerst Ergebnisse für den allgemeinen Fall präsentiert, dann werden Systeme, die linear in den Ableitungen sind, ausführlicher untersucht. Zum Abschluss wird die Theorie auf den linearen und zeitinvarianten Fall angewandt.