bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insight Into the Kinetic of Amyloid β (1–42) Peptide Self‐Aggregation: Elucidation of Inhibitors’ Mechanism of Action
Authors: Bartolini Manuela , Bertucci Carlo , Bolognesi Maria Laura , Cavalli Andrea , Melchiorre Carlo , Andrisano Vincenza 
Published: October 2007

AbstractThe initial transition of amyloid β (1–42) (Aβ42) soluble monomers/small oligomers from unordered/α‐helix to a β‐sheet‐rich conformation represents a suitable target to design new potent inhibitors and to obtain effective therapeutics for Alzheimer's disease. Under optimized conditions, this reliable and reproducible CD kinetic study showed a three‐step sigmoid profile that was characterized by a lag phase (prevailing unordered/α‐helix conformation), an exponential growth phase (increasing β‐sheet secondary structure) and a plateau phase (prevailing β‐sheet secondary structure). This kinetic analysis brought insight into the inhibitors' mechanism of action. In fact, an increase in the duration of the lag phase can be related to the formation of an inhibitor–Aβ complex, in which the non‐amyloidogenic conformation is stabilized. When the exponential rate is affected exclusively, such as in the case of Congo red and tetracycline, then the inhibitor affinity might be higher for the pleated β‐sheet structure. Finally, by adding the inhibitor at the end of the exponential phase, the soluble protofibrils can be disrupted and the Aβ amyloidogenic structure can revert into monomers/small oligomers. Congo red and tetracycline preferentially bind to amyloid in the β‐sheet conformation because both decreased the slope of the exponential growth, even if to a different extent, whereas no effect was observed for tacrine and galantamine. Some very preliminary indications can be derived about the structural requirements for binding to nonamyloidogenic or β‐sheet amyloid secondary structure for the development of potent antiaggregating agents. On these premises, memoquin, a multifunctional molecule that was designed to become a drug candidate for the treatment of Alzheimer's disease, was investigated under the reported circular dichroism assay and its anti‐amyloidogenic mechanism of action was elucidated.
Integrated, Electrically Contacted NAD(P)+‐Dependent Enzyme–Carbon Nanotube Electrodes for Biosensors and Biofuel Cell Applications
Authors: Yan Yi‐Ming , Yehezkeli Omer , Willner Itamar 
Published: October 2007

AbstractIntegrated, electrically contacted β‐nicotinamide adenine dinucleotide‐ (NAD+) or β‐nicotinamide adenine dinucleotide phosphate‐ (NADP+) dependent enzyme electrodes were prepared on single‐walled carbon nanotube (SWCNT) supports. The SWCNTs were functionalized with Nile Blue (1), and the cofactors NADP+ and NAD+ were linked to 1 through a phenyl boronic acid ligand. The affinity complexes of glucose dehydrogenase (GDH) with the NADP+ cofactor or alcohol dehydrogenase (AlcDH) with the NAD+ cofactor were crosslinked with glutaric dialdehyde and the biomolecule‐functionalized SWCNT materials were deposited on glassy carbon electrodes. The integrated enzyme electrodes revealed bioelectrocatalytic activities, and they acted as amperometric electrodes for the analysis of glucose or ethanol. The bioelectrocatalytic response of the systems originated from the biocatalyzed oxidation of the respective substrates by the enzyme with the concomitant generation of NAD(P)H cofactors. The electrocatalytically mediated oxidation of NAD(P)H by 1 led to amperometric responses in the system. Similarly, an electrically contacted bilirubin oxidase (BOD)–SWCNT electrode was prepared by the deposition of BOD onto the SWCNTs and the subsequent crosslinking of the BOD units using glutaric dialdehyde. The BOD–SWCNT electrode revealed bioelectrocatalytic functions for the reduction of O2 to H2O. The different electrically contacted SWCNT‐based enzyme electrodes were used to construct biofuel cell elements. The electrically contacted GDH–SWCNT electrode was used as the anode for the oxidation of the glucose fuel in conjunction with the BOD–SWCNT electrode in the presence of O2, which acted as an oxidizer in the system. The power output of the cell was 23 μW cm−2. Similarly, the AlcDH–SWCNT electrode was used as the anode for the oxidation of ethanol, which was acting as the fuel, with the BOD–SWCNT electrode as the cathode for the reduction of O2. The power output of the system was 48 μW cm−2.
Water‐Soluble, Electroactive, and Photoluminescent Quaterthiophene–Dinucleotide Conjugates
Authors: Alesi Silvia , Brancolini Giorgia , Melucci Manuela , Capobianco Massimo Luigi , Venturini Alessandro , Camaioni Nadia , Barbarella Giovanna 
Published: October 2007

AbstractQuaterthiophene–dinucleotide conjugates 5′TA3′‐t4‐3′AT5′, 5′AA3′‐t4‐3′AA5′, and 5′TT3′‐t4‐3′TT5′ (TA: thymidine–adenosine, AA: adenosine–adenosine, TT: thymidine–thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra‐ and intermolecular nucleobase–thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases.
Homochiral Oligopeptides via a Lattice‐Controlled Polymerisation in Racemic Crystals of Valine N‐Carboxyanhydride Suspended in Aqueous Solutions
Authors: Eliash Ran , Nery Jose G. , Rubinstein Irena , Clodic Gilles , Bolbach Gérard , Weissbuch Isabelle , Lahav Meir 
Published: October 2007

AbstractAs part of our program on the biochirogenesis of homochiral peptides, we report the formation of racemic parallel (p) β sheets composed of alternating R and S chains of up to 14–15 repeat units of the same handedness through the polymerisation of (R,S)‐valine N‐carboxyanhydride (NCA) crystals suspended in aqueous solutions of a primary amine as the initiator. The occurrence of such a lattice‐controlled reaction accompanied by a reduction in volume implies the operation of a mechanism that differs from that of the common solid‐state polymerisation in vinyl systems. The topotacticity of the reaction is explained through the operation of a multistep nonlinear process comprising lattice control coupled with an asymmetric induction in the formation of homochiral short peptides followed by their self‐assembly into racemic p β sheets, which operate as efficient templates in the ensuing process of enantioselective chain elongation at the polymer/crystal interface. The composition of the diastereoisomeric libraries of oligopeptides was determined by MALDI‐TOF and MALDI‐TOF‐TOF MS analyses of the products obtained from monomers enantioselectively labelled with deuterium. The structure of the p β sheets could be determined by initiating the polymerisation reaction with water‐soluble esters of enantiopure α‐amino acids or short peptides. The same reaction performed with the monomer crystals suspended in hexane yielded a complex mixture of diastereoisomeric oligopeptides, thus highlighting the indispensable role played by water in controlling the stereoselectivity of the reaction. By contrast, polymerisation of (R,S)‐leucine NCA crystals, with a different packing arrangement that presumably does not endorse the formation of periodic peptide templates, yielded, both in aqueous and hexane suspensions, libraries of peptides dominated by heterochiral diastereoisomers.
Ein Verfahren zur automatisierten Herstellung von Mikrodüsen aus Glaskapillaren zur Tropfenerzeugung
Authors: Harnisch J. , Irlinger F. , Lüth T. 
Published: October 2007

AbstractDieser Artikel beschreibt ein neuartiges Verfahren zur automatisierten Herstellung feiner Düsen aus Glaskapillaren. Es wird damit möglich, ohne optische Überwachung des Vorgangs sehr gut reproduzierbare Düsendurchmesser zu erhalten. Um Glaskapillaren an ihrem Ende mit einer feinen Düse zu versehen, existieren im Wesentlichen zwei Methoden: das aktive Langziehen des erhitzten Röhrchens und das kraftfreie Anschmelzen des Röhrchens, wobei sich der Innendurchmesser durch die Oberflächenspannung des verflüssigten Glases verengt. Speziell mit der letzteren Methode werden Düsen erzeugt, deren Kontur sich besonders zur Dosierung kleinster Flüssigkeitsmengen eignet. Um dabei einen definierten Düsendurchmesser zu erreichen, muss der Schmelzprozess zum richtigen Zeitpunkt angehalten werden. Im Folgenden wird ein Verfahren beschrieben, wie während des Schmelzprozesses das Erreichen des gewünschten Innendurchmessers automatisch erkannt werden kann, so dass eine serienmäßige Herstellung der Düsen ermöglicht wird. In Versuchen wurden Düsendurchmesser zwischen 35 und 200 μm aus Borosilikatglasröhrchen mit einem Außendurchmesser von 1,95 mm hergestellt. Diese Düsen dienen zur gezielten Dosierung von Tröpfchen aus Wasser, Polymeren und auch flüssigen Metallen, z. B. Lötzinn, mit einer Viskosität von etwa 1 – 40 mPas.
Zweidruck‐Batchdestillation zur Trennung homogener azeotroper Gemische
Authors: Klein A. , Repke J.‐U. 
Published: October 2007

AbstractIm Rahmen dieser Arbeit wird der Einsatz des Zweidruckverfahrens im Batchbetrieb systematisch analysiert und diskutiert. Hierzu wird ein neu entwickeltes, experimentell validiertes rigoroses Modell, das das Anfahren aus dem kalten und leeren Zustand berücksichtigt, zur Durchführung der Simulationsstudie genutzt. Ein entscheidender Einflussfaktor ist das volumetrische Verhältnis von zu trennendem Gemisch zu Feedstrom. Die Ergebnisse lassen eine Auswahl der geeigneten Prozesskombination von regulärem und inversem Batchprozess für den Zweidruckbetrieb in Abhängigkeit der Feedkonzentration und Produktreinheiten zu. Es ergeben sich für das untersuchte homogene azeotrope Gemisch Konzentrationsbereiche, in denen mit dem inversen Prozess schneller und energetisch günstiger getrennt werden kann.
Prozessoptimierung: Methoden, Anwendungen und Herausforderungen
Authors: Li Pu 
Published: October 2007

AbstractEine immer wichtigere Rolle spielt die Prozessoptimierung in der modernen Industrie. In diesem Beitrag wird ein Überblick über neue Entwicklungen der wesentlichen Methoden zur Prozessoptimierung und ihre Anwendungen in der Chemieindustrie gegeben. Es handelt sich insbesondere um die wichtigsten Aspekte der Prozessoptimierung, nämlich die dynamische Optimierung großer Systeme, die Optimierung unter Unsicherheiten und die Echtzeitoptimierung. Darüber hinaus werden Ergebnisse aus eigenen Forschungsarbeiten in diesen Gebieten präsentiert, sowohl die methodische Entwicklung als auch die praktische Anwendung. Weiterhin werden die Herausforderungen und zukünftige Anwendungen der Prozessoptimierung diskutiert.
Optimierung des Betriebs einer Nebengewinnungsanlage in Bezug auf Verfahrenstechnik und Wirtschaftlichkeit durch Einsatz eines dynamischen Prozessmodells
Authors: Liszio P. , Thielert H. , Leuchtmann K. P. , Scheckreiter D. 
Published: October 2007

AbstractDie Anwendung der chemischen Absorption als Verfahren der Luftreinhaltung ist Stand der Technik, jedoch stellen die steigenden Anforderungen an die Reinheit der Gasemissionen (TA‐Luft und Neufassungen) bei den gängigen Verfahren deren Wirtschaftlichkeit immer wieder zur Diskussion. Üblicherweise werden für Nebengewinnungsanlagen Prozessleitsysteme für die Anlagenautomatisierung eingesetzt. Diese Prozessleitsysteme sind in der Lage, Einzelregelungen durchzuführen, deren Vorgabe von den eingesetzten Bedienern kommt. Je nach Anlagenverständnis dieser Bediener wird die jeweilige Anlage gut oder schlecht gefahren. Mit Hilfe des Automatisierungsmodells GTC sind Betreiber von Kokereigasentschwefelungsanlagen in der Lage, die Vorgaben für die Einzelregelungen aus dem Modell GTC zu berechnen und an das Prozessleitsystem zu übertragen. Diese Vorgehensweise stellt sicher, dass die Vorgaben für die Einzelregler aufeinander abgestimmt sind und den betrieblichen Anforderungen entsprechen. Es wird am Beispiel der Kokereigasbehandlung TKS gezeigt wie das Modell GTC in den betrieblichen Prozess integriert wurde und wie die real gefundenen Messwerte mit den berechneten Messwerten übereinstimmten. Des Weiteren wird über die betriebliche Akzeptanz der Modelle berichtet.
Optimale Versuchsplanung in der chemischen Verfahrenstechnik
Authors: Arellano‐Garcia H. , Schöneberger J. , Körkel S. 
Published: October 2007

AbstractDie Verwendung von Modellen für Designaufgaben, Prozessführung und Optimierung von Teilprozessen oder Gesamtanlagen ist zu einer gängigen Vorgehensweise in der Prozessindustrie geworden. Allerdings hängt die Qualität der Modellaussagen zur Beschreibung der zugrunde liegenden Phänomene von der Modellstruktur und von den Werten der enthaltenen Parameter ab, die im Rahmen einer Modellvalidierung unter Verwendung von experimentellen Daten anzupassen sind. Der Weg über die Parameteridentifikation durch Aufprägung von Störungen bzw. Sprungfunktionen ist eine weit verbreitete Methode insbesondere für Systeme, die durch lineare Modelle dargestellt werden. Für nichtlineare Systeme ist jedoch die Wahl der durchzuführenden Experimente im Hinblick auf die Festlegung der Modellstruktur, der Genauigkeit und der Zuverlässigkeit von Modellparametern sowie der Reduzierung des experimentellen Aufwandes ausschlaggebend. Die Entscheidung zur Durchführung von entsprechenden Experimenten stellt daher einen Kompromiss zwischen der Qualität der aufgenommenen Daten sowie Anzahl und Art der Experimente dar. Durch optimale Auslegung von Experimenten kann die Zuverlässigkeit der Schätzung maximiert werden. Dieser Beitrag beschreibt die Formulierung von Parameterschätz‐ und Versuchsplanungsproblemen, diskutiert Methoden zu deren numerischer Behandlung und demonstriert an einem Beispiel den erfolgreichen Einsatz der Methoden.
The Slow Molecular Mobility in Amorphous Trehalose
Authors: Moura Ramos Joaquim J. , Pinto Susana S. , Diogo Hermínio P. 
Published: October 2007

AbstractThe molecular mobility in amorphous trehalose is studied by thermally stimulated depolarisation currents (TSDC). The effect of aging on the sub‐Tg motional processes was analysed during annealing at a given aging temperature, some degrees below the calorimetric glass transition temperature Tg=115 °C. The features of different motional components of the secondary relaxation are monitored as a function of time as the glass structurally relaxes on aging. The faster components of the secondary relaxation are negligibly dependent on aging and may be ascribed to intramolecular modes of motion, while the slower motional modes show a significant dependence on aging consisting of some kind of local motions with some intermolecular nature. The dielectric strength of this relaxation decreases with increasing aging time, and there is no evidence for any modification with aging of the relaxation time of this local mobility. The TSDC study of the molecular mobility of amorphous trehalose in the temperature region of the glass transformation provides the unexpected result that no glass transition signal is observable in this temperature region.
Correlation between Na* Emission and “Chemically Active” Acoustic Cavitation Bubbles
Authors: Sunartio Devi , Yasui Kyuichi , Tuziuti Toru , Kozuka Teruyuki , Iida Yasuo , Ashokkumar Muthupandian , Grieser Franz 
Published: October 2007

AbstractThe emission from electronically excited sodium atoms (Na*) from aqueous solutions containing NaCl or sodium dodecylsulfate under ultrasonic irradiation is studied. Evidence is presented that strongly suggests Na* emission arises from a population of bubbles that are sonochemically active but not producing sonoluminescence (SL). Results indicate that the Na* emission intensity is mainly dependent on the concentration of Na+ ions near the bubble/solution interface. The results provide further insight into the origin of alkali metal spectral line emission from sonicated aqueous solutions containing sodium ions.
The microenvironment of the embryonic neural stem cell: Lessons from adult niches?
Authors: Lathia Justin D. , Rao Mahendra S. , Mattson Mark P. , ffrench‐Constant Charles 
Published: October 2007

AbstractA better understanding of the signals regulating embryonic neural stem cells is clearly an important goal. However, many studies on neural stem cell biology are conducted on the slowly‐dividing cells found in the adult CNS, where specialized microenvironments or niches maintain the stem cells throughout life. By contrast, the embryonic VZ is a transient structure that does not fulfill the criteria conventionally used to define niches. In this review we will examine whether, despite these differences, the signals found in other adult stem cell niches are present in the VZ. Using the similarities and differences we observe, we will re‐consider whether the location of embryonic stem cell populations such as the VZ can be thought of as niches. Finally, we will ask how these lessons from the niche inform our understanding of neurodevelopmental diseases and cancers of the CNS. Developmental Dynamics 236:3267–3282, 2007. © 2007 Wiley‐Liss, Inc.
Characterization of the enigma family in zebrafish
Authors: Ott Elisabeth B. , Sakalis Philippe A. , Marques Ines J. , Bagowski Christoph P. 
Published: October 2007

AbstractThe three Enigma subfamily proteins, Enigma, Enigma homologue, and Cypher/ZASP belong to the PDZ and LIM encoding protein family, which is characterized by the presence of a PDZ‐ and one or more LIM domains. PDZ/LIM proteins play important biological roles, and all members have been shown to associate with the actin cytoskeleton. We describe here the splice form specific expression patterns for the three Enigma subfamily members during zebrafish embryogenesis. Whole‐mount in situ hybridization revealed common and distinct expression patterns for the different PDZ or LIM domain encoding splice variants. We further studied the role of enigma in zebrafish development. Enigma knockdown appeared to be embryonic lethal shortly after the end of gastrulation and in few surviving embryos led to elongation defects and disorganized somites. In summary, we show here the temporal and spatial expression patterns of the three Enigma family members and their PDZ and LIM domain encoding splice forms during zebrafish embryogenesis. Our results suggest that enigma is important for the formation and organization of somites and might play an important role for actin cytoskeleton organization during development. Developmental Dynamics 236:3144–3154, 2007. © 2007 Wiley‐Liss, Inc.
Correlation between recent thymic emigrants and CD31+ (PECAM‐1) CD4+ T cells in normal individuals during aging and in lymphopenic children
Authors: Junge Sonja , Kloeckener‐Gruissem Barbara , Zufferey Romain , Keisker Andre , Salgo Bettina , Fauchere Jean‐Claude , Scherer Franziska , Shalaby Tarek , Grotzer Michael , Siler Ulrich , Seger Reinhard , Güngör Tayfun 
Published: October 2007

AbstractCD31+CD45RA+RO– lymphocytes contain high numbers of T cell receptor circle (TREC)‐bearing T cells; however, the correlation between CD31+CD4+ lymphocytes and TREC during aging and under lymphopenic conditions has not yet been sufficiently investigated. We analyzed TREC, telomere length and telomerase activity within sorted CD31+ and CD31– CD4+ lymphocytes in healthy individuals from birth to old age. Sorted CD31+CD45RA+RO– naive CD4+ lymphocytes contained high TREC numbers, whereas CD31+CD45RA–RO+ cells (comprising ⩽5% of CD4+ cells during aging) did not contain TREC. CD31+ overall CD4+ cells remained TREC rich despite an age‐related tenfold reduction from neonatal (100 : 1000) to old age (10 : 1000). Besides a high TREC content, CD31+CD45RA+RO–CD4+ cells exhibited significantly longer telomeres and higher telomerase activity than CD31–CD45RA+RO–CD4+ cells, suggesting that CD31+CD45RA+RO–CD4+ cells represent a distinct population of naive T cells with particularly low replicative history. To analyze the value of CD31 in lymphopenic conditions, we investigated six children after allogeneic hematopoietic stem cell transplantation (HSCT). Reemerging overall CD4+ as well as naive CD45RA+RO–CD4+ cells predominantly expressed CD31 and correlated well with the recurrence of TREC 5–12 months after HSCT. Irrespective of limitations in the elderly, CD31 is an appropriate marker to monitor TREC‐rich lymphocytes essentially in lymphopenic children after HSCT.
Human anti‐saliva immune response following experimental exposure to the visceral leishmaniasis vector, Lutzomyia longipalpis
Authors: Vinhas Vera , Andrade Bruno B. , Paes Fábio , Bomura Andréa , Clarencio Jorge , Miranda José C. , Báfica André , Barral Aldina , Barral‐Netto Manoel 
Published: October 2007

AbstractExperiments in animals verified that phlebotomine saliva enhances Leishmania infection, and vaccination with saliva prevents disease. We have shown that individuals from an endemic area of visceral leishmaniasis displayed robust antibody responses to saliva from the vector Lutzomyia longipalpis, which correlated with anti‐parasite cell‐mediated immunity. Here, we explored human anti‐saliva responses following exposure to sand flies, using an in vivo bite model in which normal volunteers were exposed four times to 30 laboratory‐reared Lu. longipalpis. Following the third exposure, normal volunteers developed diverse dermatological reactions at the site of insect bite. Serum from normal volunteers displayed high levels of anti‐salivary gland sonicate IgG1, IgG4 and IgE as well as several salivary gland proteins. Furthermore, following in vitro stimulation with salivary gland sonicate, there was an increased frequency of CD4+CD25+ and CD8+CD25+ T cells as well as IFN‐γ and IL‐10 synthesis. Strikingly, 1 year after the first exposure, PBMC from the volunteers displayed recall IFN‐γ responses that correlated with a significant reduction in infection rates using a macrophage‐lymphocyte autologous culture. Together, these data suggest that human immunization against sand fly saliva is feasible and recall responses are obtained even 1 year after exposure, opening perspectives for vaccination in man.
New Mixed‐Metal Aggregates Derived From Dinickel Complexes on a 2‐Formylphenolate Template: Counteranion Dependent Formation of 1D Chain and Discrete NaNi2 Complexes
Authors: Paital Alok Ranjan , Mikuriya Masahiro , Ray Debashis 
Published: October 2007

AbstractThe combination of 2‐formylphenol (Hfp) and the dinucleating ligand H3L {2‐(2′‐hydroxyphenyl)‐1,3‐bis[4‐(2‐hydroxyphenyl)‐3‐azabut‐3‐enyl]‐1,3‐imidazolidine} with Ni(NO3)2·6H2O leads to the self‐assembly of a Ni2 complex capable of showing anion dependent Na+ coordination. The terminal aqua coordinated [Ni2(fp)L(H2O)]·3H2O (1·3H2O) neutral fragment, formed in the absence of any Na+ source, produces a 1D chain complex [{Ni2(fp)L(N3)(Na)(H2O)}·5H2O]n (2·5H2O)n and a discrete NaNi2 complex [Ni2(fp)L(Na)(H2O)2]·ClO4·H2O (3·ClO4·H2O) through its weak oxophilic interaction with a Na+ cation of the coordinated trisphenolate unit of L3– as observed in metallacrowns. In complexes 2 and 3, the NiII ions are coupled ferromagnetically to yield S = 2 ground states. The magnetic data can be modeled by using the Van Vleck equation incorporating intermolecular interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)