bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulator neuronaler Gene: Zinkfingerprotein REST
Authors: Thiel Gerald , Lietz Michael 
Published: March 2004

AbstractDie molekulare Grundlage für die Unterschiede zwischen einzelnen Zelltypen liegt in der spezifischen Genexpression. Das Zinkfingerprotein RE‐1 Silencing Transcription Factor (REST), ein transkriptioneller Repressor, der hauptsächlich in nicht‐neuronalen Zellen synthetisiert wird, bindet an die regulatorische Region vieler neuronaler Gene und verhindert deren Expression in nicht‐neuronalen Zellen. In Nervenzellen ist REST nur in extrem geringer Konzentration zu finden, so dass die Expression neuronaler Gene nicht blockiert wird. Der molekulare Mechanismus der transkriptionellen Repression via REST beruht auf einer Änderung der Chromatinstruktur.
Das Pfeilgift der Kalahari‐San: Tödliche Käferlarven
Authors: Neuwinger Hans‐Dieter 
Published: March 2004

AbstractDie San oder Buschmänner der Kalahari im südlichen Afrika verwenden seit jeher Larven von auf Commiphora und Sclerocarya lebenden Käfern als Quelle für ihre Pfeilgifte. Es handelt sich dabei um Larven von pflanzenfressenden Blattkäfern (Diamphidia‐ und Polyclada‐Arten) und auf ihnen schmarotzenden, fleischfressenden Laufkäfern (Lebistina‐Arten). In den letzten 25 Jahren gelang es, das giftige Prinzip zu isolieren. Das Diamphidiatoxin genannte Toxin erwies sich als ein mit Wasser leicht extrahierbares, hitzeempfindliches, basisches Protein vom Molgewicht 50.000 — 60.000, einem isolelektischen Punkt bei 8, 0 — 9, 5 und hoher Letalität bei Labortieren. Es wirkt sowohl auf rote Blutzellen als auch auf alle erregbaren Zellen. Eine extrem schnelle, massive Hämolyse und die Störung des Eletrolytgleichgewichts stehen im Vordergrund; Neurotoxizität, Krämpfe, Schwäche und Lähmung sind weitere wichtige Aspekte seiner Wirkung. Es bestehen zum Teil noch erhebliche Diskrepanzen in der endgültigen Beurteilung des Giftes. Kokons, Larven, Käfer und Giftpfeile werden in Fotos vorgestellt.
Salzliebende Mikroorganismen: Leben am Rande der Löslichkeit von Kochsalz
Authors: Zimmermann Peter , Pfeifer Felicitas 
Published: March 2004

AbstractEinige Mikroorganismen können Lebensräume besiedeln, die Salzkonzentrationen bis zur maximalen Löslichkeit von NaCl enthalten. Für das Leben bei hohen Salzkonzentrationen haben diese Mikroorganismen spezielle Strategien entwickelt, um ihr Cytoplasma isoosmotisch zum Außenmedium zu halten. Bei der compatible‐solutes‐Strategie werden intrazellulär große Mengen kleiner organischer Moleküle angereichert, die selbst in hohen intrazellulären Konzentrationen die Funktion der nicht an hohe Salzkonzentrationen angepassten Enzyme erlauben. Bei der salt‐in‐Strategie hat die Evolution die Proteine der Halobakterien in ihrer Struktur und ihren chemischen Eigenschaften so angepasst, dass sie bei hohen Salzkonzentrationen aktiv sind und im Cytoplasma eine iso‐osmotische Menge an KCl angereichert werden kann. Um in den hypersalinen Lebensräumen zu den oberen Gewässerschichten zu gelangen, wo Licht und Sauerstoff ausreichend verfügbar sind, bilden einige halophile Archaea Gasvesikel, um ihre Schwebdichte zu verringern.
Paul Berg
Authors: Bandara Samuel 
Published: March 2004

Abstract1972 schuf Paul Berg die erste rekombinante DNA und erhielt dafür 1980 den Nobelpreis. Sein Name wird verbunden mit der legendären Asilomar‐Konferenz zur Sicherheit in der gentechnischen Forschung (1975). Als prominenter Fürsprecher der Stammzellforschung engagiert er sich in der aktuellen politischen Diskussion.
Atlas der Fledermauswanderungen
Authors: Irsch Wilhelm 
Published: March 2004

AbstractNicht nur unter Vögeln, auch unter Säugetieren gibt es Zugverhalten. Die rund 38 europäischen Fledermausarten zeigen wie ihre gefiederten Wirbeltierverwandten ein ganz unterschiedliches Wanderverhalten: Einige sind Fernwanderer, andere Mittelstreckenzieher und wieder andere sind ausgesprochen standorttreu. Am Bonner Zoologischen Forschungsinstitut und Museum Alexander Koenig (ZFMK) wird nun ein Atlas der Fledermauswanderungen in Mitteleuropa erarbeitet, der als wesentliche Informationsgrundlage für den europaweiten Fledermausschutz (EUROBATS) dienen kann.
Schnecke als Gärtnerin
Authors: Knoll Ulrike 
Published: March 2004

AbstractIn den Salzmarschen entlang der nordamerikanischen Atlantikküste legt eine Schnecke auf zerfaserten Blättern „Beete”︁ an, auf denen Pilze wachsen. Gut gedüngt mit eigenem Mist keimt das Saatgut — und belohnt die Gärtnerin mit einer reichen Ernte.
Zauberkünstler Geruchsrezeptor
Authors: Brennicke Axel 
Published: March 2004

AbstractJapanische Forscher fanden heraus, dass der aktive chemische Rezeptor in einer Geruchsnervenzelle alle Gene für andere Rezeptoren abschaltet. Diese Rezeptoren sind damit wahre Wundermoleküle, die neben ihrer eigentlichen Aufgabe als Chemosensoren zusätzlich die Wachstumsrichtung der Riechnervenzellen bestimmen und bei der Genschaltung mitmischen.
Delayed portal vein thrombosis after experimental radiofrequency ablation near the main portal vein
Authors: Ng K K C , Lam C M , Poon R T P , Shek T W H , Fan S T , Wong J 
Published: March 2004

Abstract

Background
Portal venous blood flow may protect adjacent tumour cells from thermal destruction with radiofrequency ablation (RFA). This study aimed to investigate the local effect of RFA on the main portal vein branch, and the completeness of cellular ablation in its vicinity, with or without a Pringle manoeuvre using a porcine model.

Methods
This was an in vivo study on 23 domestic pigs. RFA using a cooled-tip electrode was performed 5 mm from the left main portal vein branch under ultrasonographic guidance for 12 min with (n = 10) or without (n = 10) a Pringle manoeuvre. Ten pigs were killed 4 h after the procedure to study the early effects of RFA and ten others were killed 1 week later to determine any delayed effect. As a control, sham operations with a Pringle manoeuvre for 12 min were performed on three pigs. The flow velocity changes of portal vein and hepatic artery were measured using Doppler ultrasonography, and the completeness of cellular ablation around the portal vein was assessed qualitatively by histochemical staining and quantitatively by measuring intracellular levels of adenosine 5′-triphosphate (ATP).

Results
In the absence of the Pringle manoeuvre, there was no significant change in mean(s.d.) portal vein flow velocity before RFA (20·0(3·5) cm/s) and at 4 h (18·5(2·5) cm/s) (P = 0·210) and 1 week (19·5(2·2) cm/s) (P = 0·500) after the procedure. Gross and histological examination of the portal vein branches showed no damage without the Pringle manoeuvre. In all pigs that underwent RFA with a Pringle manoeuvre, the portal vein was occluded 1 week after the operation; histological examination of the affected portal vein showed severe thermal injury and associated venous thrombosis. The local effect of RFA on the hepatic artery was similar. With intact portal blood flow during RFA, complete ablation of liver tissue around the pedicle was demonstrated by histochemical staining and measurement of the intracellular ATP concentration.

Conclusion
RFA was safe when applied close to the main portal vein branch without a Pringle manoeuvre, with complete cellular destruction. Use of the Pringle manoeuvre resulted in delayed portal vein and hepatic artery thrombosis and injury to the hepatic artery and bile duct.
An HPLC method for the quantiﬁcation of sterols in edible seaweeds
Authors: Sánchez‐Machado D. I. , López‐Hernández J. , Paseiro‐Losada P. , López‐Cervantes J. 
Published: March 2004

AbstractThis study presents an HPLC method for the quantiﬁcation of sterols in edible seaweeds. Sterols were identiﬁed by HPLC/mass spectrometry (HPLC‐MS) in positive APCI mode. The samples were saponiﬁed by reﬂuxing with 1 m ethanolic KOH, and the non‐saponiﬁable fraction was extracted with hexane. Sterols were quantiﬁed by HPLC with UV detection (HPLC‐UV), on a 15 × 0.4 cm Kromasil 100 C18 5 µm column (mobile phase 30:70 v/v methanol:acetonitrile; ﬂow rate 1.2 mL/min; column temperature 30°C; detection wavelength 205 nm). Method repeatability for fucosterol was good (coefﬁcient of variation 2.4%). Sterol contents were determined in canned or dried brown seaweeds (Himanthalia elongata, Undaria pinnatiﬁda, Laminaria ochroleuca) and red seaweeds (Palmaria sp., Porphyra sp.). The predominant sterol was fucosterol in brown seaweeds (83–97% of total sterol content; 662–2320 µg/g dry weight), and desmosterol in red seaweeds (87–93% of total sterol content; 187–337 µg/g dry weight). Copyright © 2004 John Wiley & Sons, Ltd.
HPLC study of tyrosinase inhibition by thiopronine
Authors: Girelli A. M. , Mattei E. , Messina A. 
Published: March 2004

AbstractThiopronine (N‐2‐mercaptopropionyl‐glycine, NMPG) inhibits the o‐dihydroxy‐phenolase activities of mushroom tyrosinase. When d,l‐3‐4‐dihydroxyphenylalanine (DOPA) is employed as substrate, the inhibition was found to be a competitive‐type with Ki of 0.95 µm. We found in addition that thiopronine interacts with the enzymatic generated product (o‐quinone) to form a colourless conjugate compound causing an apparent inhibition. These data suggest that thiopronine inhibits mushroom tyrosinase activity in two ways: (1) by forming an adduct with dopaquinone; and (2) by direct interaction with the enzyme probably towards the copper (II) present in the active site or cysteine‐rich domains. This ﬁnding was indicated by the presence of a lag period prior to the attainment of an inhibited steady‐state rate. Both lag period and steady‐state rate were dependent on thiopronine and substrate concentrations. An increase of thiopronine concentration causes longer lag periods as well as a concomitant decrease in the tyrosinase activity. The presence of an excess of copper (II) reverses the inhibition exerted by thiopronine. Copyright © 2004 John Wiley & Sons, Ltd.
Specifying and animating facial signals for discourse in embodied conversational agents
Authors: DeCarlo Doug , Stone Matthew , Revilla Corey , Venditti Jennifer J. 
Published: March 2004

AbstractPeople highlight the intended interpretation of their utterances within a larger discourse by a diverse set of non‐verbal signals. These signals represent a key challenge for animated conversational agents because they are pervasive, variable, and need to be coordinated judiciously in an effective contribution to conversation. In this paper, we describe a freely available cross‐platform real‐time facial animation system,RUTH, that animates such high‐level signals in synchrony with speech and lip movements.RUTHadopts an open, layered architecture in which fine‐grained features of the animation can be derived by rule from inferred linguistic structure, allowing us to useRUTH, in conjunction with annotation of observed discourse, to investigate the meaningful high‐level elements of conversational facial movement for American English speakers. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesizing multimodal utterances for conversational agents
Authors: Kopp Stefan , Wachsmuth Ipke 
Published: March 2004

AbstractConversational agents are supposed to combine speech with non‐verbal modalities for intelligible multimodal utterances. In this paper, we focus on the generation of gesture and speech from XML‐based descriptions of their overt form. An incremental production model is presented that combines the synthesis of synchronized gestural, verbal, and facial behaviors with mechanisms for linking them in fluent utterances with natural co‐articulation and transition effects. In particular, an efficient kinematic approach for animating hand gestures from shape specifications is presented, which provides fine adaptation to temporal constraints that are imposed by cross‐modal synchrony. Copyright © 2004 John Wiley & Sons, Ltd.
‘Ethylene‐Bis[phosphonate] Nucleic Acids’: Novel Monomeric Synthons for the Solid‐Phase Synthesis of (PCH2CH2P)‐Bridged Oligonucleotides
Authors: Farschtschi Nasser 
Published: March 2004

AbstractAn efficient synthesis of modified deoxyribonucleosidic building units, containing the ‘ethylene‐bisphosphonate nucleic acids’ (EBPNAs) 1 or 2, has been developed. By means of solution‐phase incorporation of 11, the oxidized form of 2, dinucleotide analogs of type 13 were prepared. The same strategy was used to incorporate 2 into the 5′‐terminal position of the 12‐mer homopolynucleotide methylphosphonate 14. A preliminary approach for solid‐phase incorporation of the nucleosidic building block 1 into a preselected position of an oligonucleotide sequence to give 19 is presented, a reaction performed by means of a coupling strategy involving catalytic oxazaphospholidine‐ring cleavage.
Polyphenols from Polygala spp. and Their Antioxidant Activity
Authors: Cervellati Rinaldo , Innocenti Gabbriella , Dall'Acqua Stefano , Costa Stefano , Sartini Elena 
Published: March 2004

AbstractMembers of Polygalaceae are known to contain a variety of different polyphenolic compounds such as xanthones, flavonoids, and biphenyl derivatives. Here, we report the isolation and structural characterization of two new phenol derivatives, named alpestrin (=3,3′,5′‐trimethoxy[1,1′‐biphenyl]‐4‐ol; 10) and alpestriose A (=6‐O‐benzoyl‐1‐O‐{6‐O‐acetyl‐3‐O‐[(4‐hydroxy‐3,5‐dimethoxyphenyl)prop‐2‐enoyl]‐β‐D‐fructofuranosyl}‐α‐D‐glucopyranoside; 11), and of four known compounds (12–15) from the MeOH extract of Polygala alpestris. The relative in vitro antioxidant activities of these compounds, in comparison with other phenolic substances from Polygala vulgaris, were evaluated by means of the BriggsRauscher (BR) oscillating reaction, a method based on the inhibitory effects of antioxidant free‐radical scavengers. The experimental antioxidant‐activity values (relative to resorcinol as a standard) were compared with those calculated on the basis of the bond‐dissociation enthalpies. The structure/activity relationships for the compounds examined are also discussed.
Extracts and Sesquiterpene Derivatives from the Red Alga Laurencia chondrioides with Antibacterial Activity against Fish and Human Pathogenic Bacteria
Authors: Bansemir Anne , Just Natalie , Michalik Manfred , Lindequist Ulrike , Lalk Michael 
Published: March 2004

AbstractDuring screening of seaweeds from different places in Europe for antimicrobial activities against human and fish pathogenic bacteria, Laurencia chondrioides was identified as a promising species. By bioassay‐guided isolation, followed by structure elucidation by mass spectrometry and 1H‐ and 13C‐NMR spectrometry, two sesquiterpenoides of the chamigrene‐type from the selected red seaweed Laurencia chondrioides were identified. Both compounds inhibit the growth of some fish and human pathogenic bacteria.
Associating Hyaluronan Derivatives: A Novel Horizon in Viscosupplementation of Osteoarthritic Joints
Authors: Šoltés Ladislav , Mendichi Raniero , Kogan Grigorij , Mach Mojmír 
Published: March 2004

AbstractThe association of two high‐molecular‐weight hyaluronan (HA) derivatives, namely a β‐cyclodextrin (HAβ‐CD) and an N‐acylurea (EDCHA), dissolved in aqueous NaCl, was studied. The weight‐average of the molecular weights (Mw) of HAβ‐CD and of EDCHA was 185.3 and 86.8 kDa, respectively. However, the Mw value determined for the equimolar mixture of the two biopolymers equaled 556.0 kDa. Similarly, the radius of gyration (dimension) Rg=80.6 nm of the above equimolar mixture was significantly greater than the values found for the single macromolecules, i.e., 40.2 nm for HAβ‐CD and 23.8 nm for EDCHA. These data indicate that the two kinds of substituents, borne by the HA polymeric chains, form hostguest inclusion complexes resulting in polymacromolecular associates/aggregates.
Diastereoisomer‐Selective Inclusion Complexation of Cinchona Alkaloids with a Modified β‐Cyclodextrin: Fluorescent Behavior Enhanced by Chiral‐Tether Binding. Short Communication
Authors: Liu Yu , Yang Ying‐Wei , Zhang Heng‐Yi , Hu Bo‐Wen , Ding Fei , Li Chun‐Ju 
Published: March 2004

AbstractThe molecular 1 : 1 complexation of cinchona alkaloids by mono(6‐deoxy‐6‐{[(R)‐1‐(hydroxymethyl)propyl]amino})‐β‐cyclodextrin (1) in aqueous solution has been investigated by 2D‐NMR, fluorescence titration, and fluorescence‐lifetime experiments. Generally, with 1 as the host, in contrast to β‐cyclodextrin proper, strong binding of quinine (2; Ka=84200 M−1) and quinidine (3; Ka=27300 M−1) at pH 6.8 was observed, as monitored by an increase in fluorescence intensity, with a fair degree of diastereoisomer discrimination (ca. 3 : 1). To rationalize these results, two possible cooperative complexation modes, including specific H‐bonding interactions to the chiral tether of the cyclodextrin portion, are proposed.
Polysaccharide/Polynucleotide Complexes. Part 6
Authors: Koumoto Kazuya , Mizu Masami , Sakurai Kazuo , Kunitake Toyoki , Shinkai Seiji 
Published: March 2004

AbstractSpectroscopic properties of single‐stranded DNA/schizophyllan ternary complexes (ss‐DNA⋅2s‐SPG), induced by addition of either complementary or noncomplementary strands, have been investigated. The addition of the complementary strands to ss‐DNA⋅2s‐SPG induced the quick release of the bound ss‐DNA to the complementary strands (both DNA and RNA), whereas the ternary complex was unaffected upon addition of noncomplementary strands. Our experiments imply that SPG has complexation properties indispensable to the gene carriers. As far as we know, there is no report on exploitation of such nonviral gene carriers that can accomplish an intelligent release of the bound ss‐DNA toward the complementary strands. We believe, therefore, that SPG, a natural and neutral polysaccharide, has a great potential to become a new ss‐DNA carrier.
Antimicrobial and Cytotoxic Activities of Neolignans from Magnolia officinalis
Authors: Syu Wan‐Jr , Shen Chien‐Chang , Lu Jang‐Jih , Lee Gum‐Hee , Sun Chang‐Ming 
Published: March 2004

AbstractIn the light of the steady increase of infections related to vancomycin‐resistant enterococci (VRE) and methicillin‐resistant Staphylococcus aureus (MRSA), the medicinal plant Magnolia officinalis was subjected to bioassay‐directed fractionation, which led to the isolation of the known neolignans piperitylmagnolol (1), magnolol (2), and honokiol (3) from the MeOH extract. In broth‐microdilution assays, 1–3 exhibited antibacterial activities against VRE and MRSA at minimum‐inhibitory concentrations (MIC) in the range of 6.25–25 μg/ml, compound 1 being the most‐potent antibiotic. The ratio of MBC/MIC (MBC=minimum bactericidal concentration) was ≤2 for all compounds. The kinetics of the antibacterial action of 1 and 3 were studied by means of time‐kill assays; both compounds were bactericidal against VRE and MRSA, their actions being time dependent, or both time and concentration dependent. Magnolol (2) was acetylated to magnolol monoacetate (4) and magnolol diacetate (5) (partial or full masking of the phenolic OH functions). The cytotoxic properties of 1–5 against human OVCAR‐3 (ovarian adenocarcinoma), HepG2 (hepatocellular carcinoma), and HeLa (cervical epitheloid carcinoma) cell lines were evaluated. The CD50 values for compounds 1–3 were in the range of 3.3–13.3 μg/ml, derivatives 4 and 5 being much less potent. This study indicates that piperitylmagnolol (=3‐[(1S,6S)‐6‐isopropyl‐3‐methylcyclohex‐2‐enyl]‐5,5′‐di(prop‐2‐enyl)[1,1′‐biphenyl]‐2,2′‐diol; 1) possesses both significant anti‐VRE activity and moderate cytotoxicity against the above cancer cell lines.
Density Functional Calculations on the Conversion of Azide and Carbon Monoxide to Isocyanate and Dinitrogen by a Nickel to Sulfur Rebound Mechanism
Authors: Fan Yubo , Hall Michael B. 
Published: March 2004

AbstractDensity functional calculations (B3 LYP & BP86) on a model system for the reaction between carbon monoxide and [Ni(N3)(′S3′)]− (′S3′2−=bis(2‐mercaptophenyl)sulfide (2−)) predict a three‐step mechanism. First, CO attacks the nickel to generate a pseudo “square‐pyramidal” complex, in which CO, N3−, and two sulfides are basal and the central S atom of the ′S3′2− ligand backs away from Ni to form a weak NiS apical bond. Then, CO inserts into the NiN bond and the weak apical NiS bond rebounds to its original strength as the nickel forms a square‐planar intermediate. Finally, in a one‐step process N2 leaves as the remaining N atom and carbonyl rearrange to produce the nickel isocyanate product [Ni(NCO)(′S3′)]−.
New Simulation Model of Multicomponent Crystal Growth And Inhibition
Authors: Wathen Brent , Kuiper Michael , Walker Virginia , Jia Zongchao 
Published: March 2004

AbstractWe review a novel computational model for the study of crystal structures both on their own and in conjunction with inhibitor molecules. The model advances existing Monte Carlo (MC) simulation techniques by extending them from modeling 3D crystal surface patches to modeling entire 3D crystals, and by including the use of “complex” multicomponent molecules within the simulations. These advances makes it possible to incorporate the 3D shape and non‐uniform surface properties of inhibitors into simulations, and to study what effect these inhibitor properties have on the growth of whole crystals containing up to tens of millions of molecules. The application of this extended MC model to the study of antifreeze proteins (AFPs) and their effects on ice formation is reported, including the success of the technique in achieving AFP‐induced ice‐growth inhibition with concurrent changes to ice morphology that mimic experimental results. Simulations of ice‐growth inhibition suggest that the degree of inhibition afforded by an AFP is a function of its ice‐binding position relative to the underlying anisotropic growth pattern of ice. This extended MC technique is applicable to other crystal and crystal–inhibitor systems, including more complex crystal systems such as clathrates.
Inorganic Electrides
Authors: Li Zhenyu , Yang Jinlong , Hou J. G. , Zhu Qingshi 
Published: March 2004

AbstractInorganic electrides are a novel kind of ionic compounds in which the anions are electrons confined in a complex array of cavities or channels and the cations are nanoscale arrays of alkali metal ions that provide charge balance. In electrides the donated electron behaves like a low‐density correlated electron gas, whereby the dimensionality of the electron gas and its electronic and magnetic properties are determined by the topology of the cavities in the host matrix. Unlike traditional electrides, in which alkali cations are encapsulated within an organic cage, inorganic electrides are thermally stable. The current inorganic electrides based on alkali metal loaded zeolites can be designed as useful reduced‐dimensionality materials. Inorganic electrides are powerful reducing agents, and they are able to reduce small aromatic molecules to the radical anions within the channels of the zeolite.