bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Palladium(II)‐Substituted, Lone Pair Containing Tungstoarsenates(III) [Na2(H2O)2PdWO(H2O)(α‐AsW9O33)2]10– and [Cs2Na(H2O)8Pd3(α‐AsW9O33)2]9–
Authors: Bi Li‐Hua , Kortz Ulrich , Keita Bineta , Nadjo Louis , Daniels Lee 
Published: June 2005

AbstractThe monopalladium(II)‐substituted [Na2(H2O)2PdWO(H2O)(α‐AsW9O33)2]10– (1) and the tripalladium(II)‐substituted [Cs2Na(H2O)8Pd3(α‐AsW9O33)2]9– (2) were synthesized in aqueous acidic medium (pH 4.8) by reaction of Pd2+ ions with [As2W19O67(H2O)]14– and [α‐AsW9O33]9–, respectively. The dimeric polyanions 1 and 2 were characterized by complete elemental analysis, FTIR, and electrochemistry. Single‐crystal X‐ray analysis was carried out on Cs3Na7[Na2(H2O)2PdWO(H2O)(α‐AsW9O33)2]·1.5NaCl·22H2O (1a), which crystallizes in the triclinic system, space group P$\bar {1}$, with a = 13.2465(16) Å, b = 16.873(2) Å, c = 23.080(3) Å, α = 107.315(2)°, β = 95.025(3)°, γ = 98.040(3)°, and Z = 2; Cs3Na6[Cs2Na(H2O)8Pd3(α‐AsW9O33)2]·NaCl·15H2O (2a) crystallizes in the monoclinic system, space group P21/m, with a = 13.1842(5) Å, b = 19.6584(7) Å, c = 18.2377(6) Å, β = 100.7660(10)°, and Z = 2. Polyanion 1 is composed of two [α‐AsW9O33]9– fragments connected by a WO(H2O) unit, one square‐planar palladium atom and two sodium ions, leading to a sandwich‐type structure with Cs symmetry. Polyanion 2 also consists of two [α‐AsW9O33]9– moieties, but these are linked by three equivalent, square‐planar Pd2+ ions, one sodium ion and two cesium ions, leading to a sandwich‐type structure with C2v symmetry. A cyclic voltammetric study of polyanion 2 in a pH 5 medium shows a Pd0 deposition process on the glassy carbon electrode surface. The corresponding wave and the waves for the tungsten redox processes could be separated clearly. The thickness of the film increases with the number of potential cycles or the duration of potentiostatic electrolysis. The deposited film proved to be very stable and efficient in the electrocatalytic reduction of dioxygen. Polyanion 1 was not sufficiently stable in solution to warrant electrochemical characterization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthetic Applications of Lawesson’s Reagent in Reactions with CuI Alkoxides
Authors: Shi Weifeng , Rothenberger Alexander 
Published: June 2005

AbstractThe reaction of Lawesson’s reagent with CuOtBu and tertiary phosphanes produced the complexes [Cu2(μ2‐ArS2P–O–PS2Ar)(PPh3)4] (1) (Ar = p‐C6H4OMe) and [Cu4{Ar(μ2‐S)2P–O–P(μ2‐S)2Ar}2(dppa)2] (2) (dppa = Ph2PNHPPh2) in high yields. The ligand [ArS2P–O–PS2Ar]2– is the first of a new family of dianionic P/S ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Exocyclic–Endocyclic N‐Acyliminium Ion Equilibration via an Intramolecular α‐Thioamidoalkylation in the Synthesis of Fused N,S‐Heterocyclic Systems: Some New Parameters
Authors: Hucher Nicolas , Pesquet Anthony , Netchitaïlo Pierre , Daïch Adam 
Published: June 2005

AbstractThe reactivity of N‐[aryl(or alkyl)thio(oxo or seleno)alkylamidals 6 bearing the N‐(CH2)n‐X‐(CH2)m‐Ar functionality towards neat TFA has been examined. Substrates of type 6 give, together with the products 11, 17, 19, and 25 of the “expected” π‐cyclization process, the “unexpected” products 12, 18, and 26 resulting from a new tandem heteroamidoalkylation/isomerization/π‐cyclization. The composition of the final isomeric mixture depends on the temperature of the reaction, with a high selectivity in favor of the “expected” π‐cyclization product 11 as a thermodynamic isomer. Furthermore, the results demonstrate again the relevance of TFA catalysis and support two reaction pathways involving the formation of an aza‐sulfonium cation A as a valuable intermediate which undergoes the π‐cyclization process alone or in tandem with the thiocyclization/isomerization to give the cyclized products cited above. For the latter tandem reaction, we have established clearly that the n value should be equal to 1, the process can be performed independently for both the succinimide and phthalimide series, the reaction depends on the nucleophilicity of the heteroatom, and can be generalized to other heterocycles. Only the role of the benzene substitution has still to be totally elucidated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Structure, and Photochromic Properties of Dithia‐(dithienylethena)phane Derivatives
Authors: Kamrul Hossain Mohammed , Takeshita Michinori , Yamato Takehiko 
Published: June 2005

AbstractDithia‐(dithienylethena)phane derivatives, composed of dithienylethene moieties and benzene bridges, were synthesized by a coupling reaction of the corresponding bis(chloromethyl)benzene with bis(mercaptomethyl)dithienylethene under high‐dilution conditions. The products exhibit photochromic properties upon irradiation with ultraviolet and visible light. The photocyclization and cycloreversion quantum yields were determined, and a relationship between the photocyclization quantum yield and distance between the reactive carbon atoms of the phane derivatives established. The ortho isomer has a high efficiency in photocyclization due to its fixation in the photo‐active anti conformation and short distance between the two reactive carbon atoms. The thermal stability of these photochromic compounds has been studied and the ortho isomer found to show thermal irreversibility. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The Dipolar Route to Azepin‐3‐one Derivatives by Heterocyclization of Linear and Monocyclic Enallenyl Nitrones as the Key Step
Authors: Knobloch Karin , Koch Joachim , Keller Manfred , Eberbach Wolfgang 
Published: June 2005

AbstractThe recently discovered transformation of benzopentenynyl nitrones into 1,2‐dihydrobenz[c]azepin‐3‐ones has been extended to the synthesis of structurally different systems including the monocyclic derivatives 17 and 18, the bicyclic azepinones 10a–d, and the tricyclic heterocycles 37–40, 42, 43, 45, 47, and 48. In addition, the applicability of the reaction principle was demonstrated through the preparation of the benzo‐piperidino compound 52 which acts as a model compound for the alkaloid astrocasine (53). A multistep reaction mechanism is proposed that involves enallenyl nitrones as precursors of a 1,7‐dipolar electrocyclization process followed by further bond reorganizations. The occurrence of cyclopropanones (type E and H) as intermediates is supported by the formation of isoindoles (41, 44, and 46) as minor products in some cases. Photochemical studies with selected dihydroazepinones gave different results: Whereas the monocyclic azepinone 17 reacted under both direct and sensitized excitation to form the bicyclic diastereomers 20 and 21, the reactions of the bicyclic compounds 10 were more complicated. Only 10a,b were observed to undergo the 4π‐cyclization reaction upon direct irradiation, resulting, after CO extrusion and hydrolysis, in the formation of the aldehydes 22a,b. Under triplet‐sensitized conditions 10b–d undergo a 1,5‐phenyl shift to afford the isomers 25b–d. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Enantioselective Diels–Alder Reaction of Acyclic Enones Catalyzed byallo‐Threonine‐Derived Chiral Oxazaborolidinone
Authors: Singh Ram Shanker , Harada Toshiro 
Published: June 2005

AbstractAn allo‐threonine‐derived O‐(p‐biphenylcarbonyloxy)‐B‐phenyl‐oxazaborolidinone is demonstrated to be a powerful and highly enantioselective Lewis acid catalyst for the enantioselective Diels–Alder reaction of simple acyclic enone dienophiles, expanding the scope of ketone dienophiles and dienes. With 10–20 mol % of the catalyst, the Diels–Alder adducts are obtained with up to 94 % ee and high endo selectivity. The catalyst exhibits a high activity in the reaction with the less reactive β‐substituted dienophiles and the less reactive 1,3‐cycohexadiene and 1,3‐butadiene derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Evaluation of two‐dimensional electrophoresis and liquid chromatography – tandem mass spectrometry for tissue‐specific protein profiling of laser‐microdissected plant samples
Authors: Schad Martina , Lipton Mary S. , Giavalisco Patrick , Smith Richard D. , Kehr Julia 
Published: June 2005

AbstractLaser microdissection (LM) allows the collection of homogeneous tissue‐ and cell‐specific plant samples. The employment of this technique with subsequent protein analysis has thus far not been reported for plant tissues, probably due to the difficulties associated with defining a reasonable cellular morphology and, in parallel, allowing efficient protein extraction from tissue samples. The relatively large sample amount needed for successful proteome analysis is an additional issue that complicates protein profiling on a tissue‐ or even cell‐specific level. In contrast to transcript profiling that can be performed from very small sample amounts due to efficient amplification strategies, there is as yet no amplification procedure for proteins available. In the current study, we compared different tissue preparation techniques prior to LM/laser pressure catapulting (LMPC) with respect to their suitability for protein retrieval. Cryo‐sectioning was identified as the best compromise between tissue morphology and effective protein extraction. After collection of vascular bundles from Arabidopsis thaliana stem tissue by LMPC, proteins were extracted and subjected to protein analysis, either by classical two‐dimensional gel electrophoresis (2‐DE), or by high‐efficiency liquid chromatography (LC) in conjunction with tandem mass spectrometry (MS/MS). Our results demonstrate that both methods can be used with LMPC collected plant material. But because of the significantly lower sample amount required for LC‐MS/MS than for 2‐DE, the combination of LMPC and LC‐MS/MS has a higher potential to promote comprehensive proteome analysis of specific plant tissues.
Influence of DNA repair gene polymorphisms on the yield of chromosomal aberrations
Authors: Kiuru Anne , Lindholm Carita , Heilimo Iiris , Ceppi Marcello , Koivistoinen Armi , Ilus Taina , Hirvonen Ari , Norppa Hannu , Salomaa Sisko 
Published: June 2005

AbstractWe evaluated the influence of several DNA repair gene polymorphisms on the frequency of chromosomal aberrations (CAs) analyzed in peripheral lymphocytes, using the fluorescence in situ hybridization technique. The CA data were obtained from an earlier study of 84 healthy nonsmokers (48 women and 36 men) carefully characterized for indoor radon exposure. The frequency of translocations showed a wide interindividual variability, which was only partly explained by age. To investigate the potential role of DNA repair polymorphisms in this variation, genotypes of DNA repair genesOGG1(codon 326),XPD(codon 751),XRCC1(X‐ray repair cross‐complementing group 1) (codons 194, 280, and 399), andXRCC3(X‐ray repair cross‐complementing group 3) (codon 241) were determined from leukocyte DNA using polymerase chain reaction‐based methods. Negative binomial regression models were applied to evaluate the effect of the polymorphisms and other factors (age, gender, radon exposure, and medical exposure) on the frequency of CAs. No interactions between genotypes and radon, medical exposure, or gender were found. Carriers of theXRCC1codon 280His variant allele had a two‐fold increase (frequency ratio [FR] = 2.01, 95% confidence interval [CI] = 1.01–3.98;P= 0.046) in unstable exchanges (dicentrics and ring chromosomes). In addition, theXRCC3codon 241 homozygous variant genotype (Met/Met) was associated with an increase (FR = 1.70, 95% CI = 1.06–2.74;P= 0.028) in two‐way translocations when age was taken into account in the analysis. Our data suggest that theXRCC1280His andXRCC3241Met alleles affect individual CA levels, most probably via influencing the DNA repair phenotype. Environ. Mol. Mutagen. 46:000–000, 2005. © 2005 Wiley‐Liss, Inc.
Cytokine toxicity to oligodendrocyte precursors is mediated by iron
Authors: Zhang Xuesheng , Haaf Michael , Todorich Bozho , Grosstephan Erin , Schieremberg Henry , Surguladze Nodar , Connor James R. 
Published: June 2005

AbstractInflammatory processes play a key role in the pathogenesis of a number of common neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Abnormal iron accumulation is frequently noted in these diseases and compelling evidence exists that iron is involved in inflammatory reactions. Histochemical stains for iron repeatedly demonstrate that oligodendrocytes, under normal conditions, stain more prominently than any other cell type in the brain. Therefore, we examined the hypothesis that cytokine toxicity to oligodendrocytes is iron mediated. Oligodendrocytes in culture were exposed to interferon‐γ (IFN‐γ), interleukin‐1β (IL‐1β), and tumor necrosis factor‐α (TNF‐α). Toxicity was observed in a dose‐dependent manner for IFN‐γ and TNF‐α. IL‐1β was not toxic in the concentrations used in this study. The toxic concentration of IFN‐γ, and TNF‐α was lower if the cells were iron loaded, but iron loading had no effect on the toxicity of IL‐1β. These data provide insight into the controversy regarding the toxicity of cytokines to oligodendrocytes by revealing that iron status of these cells will significantly impact the outcome of cytokine treatment. The exposure of oligodendrocytes to cytokines plus iron decreased mitochondrial membrane potential but activation of caspase 3 is limited. The antioxidant, TPPB, which targets mitochondria, protected the oligodendrocytes from the iron‐mediated cytotoxicity, providing further support that mitochondrial dysfunction may underlie the iron‐mediated cytokine toxicity. Therapeutic strategies involving anti‐inflammatory agents have met with limited success in the treatment of demyelinating disorders. A better understanding of these agents and the contribution of cellular iron status to cytokine toxicity may help develop a more consistent intervention strategy. © 2005 Wiley‐Liss, Inc.
Photoinduced Electron‐Transfer Processes in Fullerene‐Based Donor–Acceptor Systems
Authors: Thomas K. George , George Manapurathu V. , Kamat Prashant V. 
Published: June 2005

AbstractPhotoinduced electron‐transfer processes in fullerene‐based donor–acceptor dyads (DBA) in homogeneous and cluster systems are summarized. Stabilization of charge has been achieved through the use of fullerene substituted‐aniline/heteroaromatic dyads with tunable ionization potentials and also by using fullerene clusters. The rate constants for charge separation (kCS) and charge recombination (kCR) in fullerene substituted‐aniline/heteroaromatic dyads show that forward electron transfer falls in the normal region of the Marcus curve and the back electron transfer in the inverted region of the Marcus parabola. Clustering of fullerene‐based dyads assists in effective delocalization of the separated charge and thereby slows down the back electron transfer in these cases.
A Facile Cell Free Synthesis of Isotopically Labeled (E)‐4‐Hydroxy‐3‐methylbut‐2‐enyl Diphosphate, a Precursor of the Plant Hormone Zeatin
Authors: Raschke Maja , Fellermeier Monika , Zenk Meinhart H. 
Published: June 2005

Abstract(E)‐4‐Hydroxy‐3‐methylbut‐2‐enyl diphosphate (1) is a key intermediate of the deoxyxylulose phosphate pathway of isoprenoid biosynthesis and a precursor of the plant hormone zeatin. The availability of this intermediate with various labeling patterns is pivotal for its use in biosynthetic studies. The number of positions, however, that can be easily labeled by chemical synthesis is limited, and the synthesis by means of recombinant enzymes is laborious and time consuming. We demonstrated that chromoplasts from Capsicum annuum, whose enzyme activity was impaired by freeze‐thawing, accumulate 1. This observation built the basis for the development of a cell‐free system allowing the synthesis of this intermediate with labels in various positions. With 2C‐methyl‐D‐erythritol 2,4‐cyclodiphosphate (5) as substrate, yields were in the range of 50%.
New Tryptophan Metabolites from Cultures of the Lipophilic Yeast Malassezia furfur
Authors: Irlinger Bernhard , Bartsch Andrea , Krämer Hans‐Joachim , Mayser Peter , Steglich Wolfgang 
Published: June 2005

AbstractEleven new indole alkaloids were isolated from cultures of the human pathogenic yeast Malassezia furfur after addition of L‐tryptophan as the sole N‐source: pityriacitrin B (2), the malassezindoles A (3) and B (4), malassezialactic acid (6), the malasseziazoles A (7), B (8), and C (9), pityriazole (10), malasseziacitrin (11), and malassezione (12), along with the known d‐indole‐3‐lactic acid (=(αR)‐α‐hydroxy‐1H‐indole‐3‐propanoic acid 5), and 2‐hydroxy‐1‐(1H‐indol‐3‐yl)ethanone (13). The structural elucidation of these compounds was performed by spectroscopic methods (MS as well as 1D‐ and 2D‐NMR). The biogenetic relationships (Scheme) and biological activities of the new metabolites are discussed.
Anti‐magic graphs via the Combinatorial NullStellenSatz
Authors: Hefetz Dan 
Published: June 2005

AbstractAn antimagic labeling of a graph with m edges and n vertices is a bijection from the set of edges to the integers 1,…,m such that all n vertex sums are pairwise distinct, where a vertex sum is the sum of labels of all edges incident with that vertex. A graph is called antimagic if it has an antimagic labeling. In [10], Ringel conjectured that every simple connected graph, other than K2, is antimagic. We prove several special cases and variants of this conjecture. Our main tool is the Combinatorial NullStellenSatz (cf. [1]). © 2005 Wiley Periodicals, Inc. J Graph Theory
A comparison of noninvasive MRI‐based methods of estimating pulmonary artery pressure in pulmonary hypertension
Authors: Roeleveld Roald J. , Marcus J. Tim , Boonstra Anco , Postmus Pieter E. , Marques Koen M. , Bronzwaer Jean G.F. , Vonk‐Noordegraaf Anton 
Published: June 2005

AbstractPurposeTo assess the accuracy of several noninvasive MRI‐based estimators of pulmonary artery pressure by comparing them with invasive pressure measurement.Materials and MethodsWe compared five MRI methods with invasive pressure measurement by catheterization, in one group of pulmonary hypertension (PH) patients. Doppler echocardiography was included as a reference method. Main inclusion criterion was a mean pulmonary artery pressure above 25 mmHg at catheterization. MRI velocity quantification was used to obtain pulmonary flow acceleration and ejection times, and pulse wave velocity. The ventricular mass index was also assessed on MRI. Two commercially available 1.5‐T systems were used for this study.ResultsData from 44 patients were analyzed. Correlation of acceleration time with mean pressure was: r = –0.21, P = 0.21, correlation of the acceleration/ejection time ratio with systolic pressure was: r = –0.26, P = 0.01. The ventricular mass index showed the best correlation with mean pressure, with r = 0.56, P < 0.001. Using the pulse wave velocity and the cross‐sectional area of the pulmonary artery, the mean pressure could not be estimated accurately.ConclusionAccurate estimation of pulmonary artery pressure in PH patients was not feasible by the MRI estimators studied. These noninvasive methods cannot replace right heart catheterization at this moment. J. Magn. Reson. Imaging 2005;22:67–72. © 2005 Wiley‐Liss, Inc.
Comparison of 0.5‐M Gd‐DTPA with 1.0‐M gadobutrol for magnetic resonance angiography of the supplying arteries of the spinal cord in thoracoabdominal aortic aneurysm patients
Authors: Nijenhuis Robbert J. , Gerretsen Suzanne , Leiner Tim , Jacobs Michael J. , van Engelshoven Jos M.A. , Backes Walter H. 
Published: June 2005

AbstractPurposeTo prospectively compare 0.5‐M gadopentetate dimeglumine (Gd‐DTPA) with 1.0‐M gadobutrol for contrast‐enhanced magnetic resonance angiography (CE‐MRA) of the blood supplying arteries of the spinal cord in patients referred for open surgical repair of a thoracoabdominal aortic aneurysm (TAAA).Materials and MethodsA total of 11 patients with a TAAA underwent two three‐dimensional CE‐MRA exams of the aorta, segmental arteries (SAs), artery of Adamkiewicz (AKA), and anterior spinal artery (ASA). Imaging was performed on two separate occasions using Gd‐DTPA and gadobutrol as contrast agents at 0.3 mmol/kg. Images were evaluated by measuring signal‐to‐noise (SNR) and contrast‐to‐noise (CNR) ratios and were judged for different image quality criteria by two blinded observers.ResultsIn all patients both CE‐MRA exams were of sufficient image quality to detect the AKA and ASA. No significant differences in SNR and CNR were observed between the two contrast agents. According to the observers, no significant differences in subjective image quality were found.ConclusionsUsing both contrast agents it was possible to visualize the ultrasmall spinal cord arteries in all cases. The use of the 1.0‐M contrast agent did not improve image quality of CE‐MRA images of the blood supplying arteries of the spinal cord compared to the 0.5‐M contrast agent. J. Magn. Reson. Imaging 2005;22:136–144. © 2005 Wiley‐Liss, Inc.
Small bowel hydro‐MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?
Authors: Ajaj Waleed , Lauenstein Thomas C. , Langhorst Jost , Kuehle Christiane , Goyen Mathias , Zoepf Thomas , Ruehm Stefan G. , Gerken Guido , Debatin Jorg F. , Goehde Susanne C. 
Published: June 2005

AbstractPurposeTo assess the impact of an additional rectal enema filling in small bowel hydro‐MRI in patients with Crohn's disease.Materials and MethodsA total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast‐enhanced T1w three‐dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal‐to‐noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25).ResultsThe terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false‐negative diagnoses of terminal ileitis.ConclusionOur data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered. J. Magn. Reson. Imaging 2005;22:92–100. © 2005 Wiley‐Liss, Inc.