bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Novel Quinone–Amino Acid Hybrids via Cross‐Enyne Metathesis and Diels–Alder Reaction as Key Steps
Authors: Kotha Sambasivarao , Mandal Kalyaneswar , Banerjee Shaibal , Mobin Shaikh M. 
Published: January 2007

AbstractA “Building Block Approach” for the synthesis of various quinone‐amino acid hybrids through ethylene cross‐enyne metathesis and Diels–Alder reaction as key steps is described. A library of comformationally constrained quinone‐based phenylalanine derivatives and dicarba analogs of cystine have been generated starting from a common precursor using Grubbs' catalysts. This methodology has also been extended for the synthesis of fullerene‐based dicarba analogs of cystine.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Efficient Synthesis of Benzofurans Utilizing [3,3]‐Sigmatropic Rearrangement Triggered by N‐Trifluoroacetylation of Oxime Ethers: Short Synthesis of Natural 2‐Arylbenzofurans
Authors: Takeda Norihiko , Miyata Okiko , Naito Takeaki 
Published: January 2007

AbstractA new synthetic method for the preparation of benzofurans has been developed. The key step of this method is the [3,3]‐sigmatropic rearrangement of N‐trifluoroacetyl‐ene‐hydroxylamines, which was triggered by acylation of oxime ethers. TFAA has been proved to be the best reagent to induce [3,3]‐sigmatropic rearrangement for the synthesis of cyclic oracyclic dihydrobenzofurans. On the other hand, the TFAT‐DMAP system is found to be the most effective for constructing various benzofurans. Synthetic utility of this reaction is demonstrated by the short synthesis of natural benzofurans without protection of the hydroxy group. The synthesis of Stemofuran A was accomplished via condensation of ketones with aryloxyamine and subsequent reaction with TFAT‐DMAP in a four‐step synthesis with 72 % overall yield. Similarly, Eupomatenoid 6 and Coumestan were synthesized through the reaction of oxime ether with TFAT‐DMAP. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Enantio‐ and Diastereomerically Pure Decalins by Deslongchamps‐Type Annulation of Dienolates Containing a Chiral Lactone Substituent
Authors: Tricotet Thomas , Brückner Reinhard 
Published: January 2007

AbstractA conceptionally novel 1,3‐asymmetric induction has been established. It controls the relative and absolute configuration of up to 5 stereocenters. They emerge from the anionic Diels–Alder reactions (“Deslongchamps annulations”) between oxocyclohexenecarboxylates 25, 29 and dienolates 26, 30. The latter contain a γ‐lactone. A Ph3Si–CH2 substituent therein controls the asymmetry of C–C bond formation with ds ≈ 10:1. Strangely, the preferred sense of attack of the dienophile is contrasteric. Cycloadduct 31 was processed by an unprecedented fluoride‐induced ambient‐temperature tandem fragmentation. It turned the lactone moiety into an allyl group and the β‐oxo (trimethylsilyl)ethyl ester into a ketone. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The Thermal Transformations of Bicyclopropylidene and Methylenespiropentane Revisited
Authors: Schill Heiko , Kozhushkov Sergei I. , Walsh Robin , de Meijere Armin 
Published: January 2007

AbstractThe overall and the individual rate constants of the unimolecular thermal isomerization of methylenespiropentane (4) to 1,2‐ and 1,3‐dimethylenecyclobutanes (7 and 8) have been determined to be lg (k–4/s–1) = (13.78 ± 0.06) – (49.7 ± 0.2) kcal mol–1/RT·ln 10, lg (k7/s–1) = (13.03 ± 0.19) – (48.0 ± 0.6) kcal mol–1/RT·ln 10 and lg (k8/s–1) = (14.15 ± 0.19) – (52.4 ± 0.5) kcal mol–1/RT·ln 10, respectively. The activation energies are significantly lower than that for the rearrangement of the parent spiropentane.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Modeling and simulation of IEF in 2‐D microgeometries
Authors: Shim Jaesool , Dutta Prashanta , Ivory Cornelius F. 
Published: January 2007

AbstractA 2‐D finite‐volume model is developed to simulate nonlinear IEF in complex microgeometries. This mathematical model is formulated based on the mass conservation and ionic dissociation relations of amphoteric macromolecules, charge conservation, and the electroneutrality condition. Based on the 2‐D model, three different separation cases are studied: an IPG in a planar channel, an ampholyte‐based pH gradient in a planar channel, and an ampholyte‐based pH gradient in a contraction–expansion channel. In the IPG case, cacodylic acid (pK1 = 6.21) and Tris (pK1 = 8.3) are used as the acid and base, respectively, to validate the 2‐D IEF model. In the ampholyte‐based pH gradient cases, IEF is performed in the pH range, 6.21–8.3 using 10 ampholytes in the planar channel and 20 ampholytes in the contraction–expansion channel. The numerical results reveal different focusing efficiencies and resolution in the narrow and wide sections of the contraction–expansion channel. To explain this, the expressions for separation resolution and peak concentrations of separands in the contraction–expansion channel are presented in terms of the channel shape factor. In a 2‐D planar channel, a focused band remains straight all the time. However, in a contraction–expansion channel, initially straight bands take on a crescent profile as they pass through the trapezoidal sections joining the contraction and expansion sections.
Theory of band broadening during cycling temperature capillary electrophoresis
Authors: Laachi Nabil , Dorfman Kevin D. 
Published: January 2007

AbstractA two‐state transport model is presented for cycling temperature CE. In this high‐throughput method of mutation detection, the temperature oscillates in time, causing the DNA to periodically transit between an annealed state and a partially melted (denatured) state. The change in state alters the electrophoretic mobility, and the presence of a mutation changes the temperature dependence of the denaturing/annealing kinetics. Asymptotic formulae for the mean velocity and effective diffusivity (dispersivity) of the DNA are computed by a multiple‐time scales scheme in the limit where the DNA have experienced many temperature cycles before reaching the detector. Explicit analytical results are presented for the case where the temperature cycle consists of one interval with irreversible annealing, followed by a second interval with an infinitely fast, irreversible denaturation. The lag in the annealing leads to a reduction in the mean velocity and an enhanced dispersion compared to the idealized case where the DNA respond instantaneously to the changes in temperature, with the dispersion scaling quadratically with the electric field. The predicted plate height scales linearly with the electric field, and the optimal separation resolution is predicted for moderate values of the cycle frequency that allow the DNA to relax during each temperature oscillation.
Fluorescence in situ hybridization is necessary to detect an association between chromosome aberrations and polycyclic aromatic hydrocarbon exposure in utero and reveals nonrandom chromosome involvement
Authors: Bocskay Kirsti A. , Orjuela Manuela A. , Tang Deliang , Liu Xinhua , Warburton Dorothy , Perera Frederica P. 
Published: January 2007

AbstractChromosome aberrations are associated with environmental exposures in infants and children. Recently we reported that prenatal exposure to airborne polycyclic aromatic hydrocarbons (PAHs) was significantly (P < 0.01) associated with stable aberration frequencies in cord blood from a subset of 60 newborns from the Columbia Center for Children's Environmental Health Prospective Cohort Study (Bocskay K et al. [ 2005]: Cancer Epidemiol Biomarkers Prev 14:506–511). To determine whether the environmental exposures may be targeting specific chromosomes and to compare various methods for measuring chromosome aberrations, we further evaluated this same subset of subjects composed of African‐American and Dominican nonsmoking mother–newborn pairs residing in low‐income neighborhoods of New York City, and exposed to varying levels of airborne PAHs. Chromosome aberrations were measured in cord blood lymphocytes, both by whole chromosome probe (WCP) fluorescence in situ hybridization (FISH) and traditional Giemsa‐staining. Prenatal exposures were assessed by personal air monitoring. Breaks in chromosomes 1–6, as detected by WCP FISH, were nonrandomly distributed, underscoring the importance of appropriate chromosome probe selection to capture cytogenetic damage in response to exposure. FISH for stable aberrations was found to be a more sensitive method for detecting aberration frequencies associated with environmental exposures, when compared with FISH for unstable aberrations or Giemsa‐staining for aberrations. Together, these results suggest that PAHs may be targeting specific chromosomes and highlight the importance of using the more sensitive detection methods to assess risk in populations with low levels of exposure. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
Malpractice litigation and medical costs in Mississippi
Authors: Roberts Brandon , Hoch Irving 
Published: January 2007

AbstractThis paper examines the impact of varying levels of malpractice litigation on area medical costs. Using a fixed‐effects model and Medicare Part B as the dependent variable, the results indicate that per enrollee medical expenditures are positively related to the incidence of medical malpractice lawsuits. The higher cost is presumed to be attributable to ‘defensive practices’ by area physicians based on varying degrees of perceived risk. The results suggest the addition to cost is substantial, possibly adding up to 25% in some jurisdictions with the impact exceeding annual dollar amounts of malpractice judgments and settlements. Copyright © 2007 John Wiley & Sons, Ltd.
Fixation of mandibular osteotomies: Comparison of locking and nonlocking hardware
Authors: Kim Young , Smith Jesse , Sercarz Joel A. , Head Christian , Abemayor Elliot , Blackwell Keith E. 
Published: January 2007

AbstractBackground.The outcome of patients undergoing rigid plate fixation of symphyseal mandibular osteotomies for exposure, resection, and reconstruction of tumors in the oral cavity or oropharynx was analyzed to determine the impact of hardware selection on complications.Methods.Forty‐five patients underwent titanium plate rigid internal fixation of mandibular osteotomies during cancer resection and free flap reconstruction at an academic medical center. The incidence of hardware‐related complications and mandibular nonunion was compared in patients receiving either locking hardware or nonlocking hardware.Results.The incidence of osteotomy‐related complications in patients with an inferior border nonlocking mandibular fracture plate was 21%. In the patients with locking hardware or an inferior border nonlocking mandibular fracture plate combined with a tension band, there were no hardware‐related complications and no mandibular nonunions. This difference was statistically significant (χ2 = 6.01, p < .05).Conclusions.Locking mandibular reconstruction plates are associated with fewer complications than inferior border nonlocking mandibular fracture plates for rigid fixation of mandibular osteotomies in patients undergoing resection of head and neck cancer. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Pleomorphic adenoma of the parotid gland: Histopathologic analysis of the capsular characteristics of 218 tumors
Authors: Zbären Peter , Stauffer Edouard 
Published: January 2007

AbstractBackground.Histopathologic features of the capsule may have an impact on the recurrence rate of pleomorphic adenomas.Methods.Retrospective (n = 154) and prospective (n = 64) histologic analysis of the capsular characteristics such as incompleteness, tumor penetration, pseudopodia, and satellite tumors of 218 pleomorphic adenomas.Results.In 160 of the 218 (73%) pleomorphic adenomas, 1 or more capsular characteristics such as incomplete capsule (33%), capsule penetration (26%), pseudopodia (40%), and satellite nodules (13%) were detected. Incomplete capsule and satellite tumors were most frequently seen in the stroma‐rich (myxoid) subtype. Capsular penetration and pseudopodia were significantly more common in the prospective group than in the retrospective group (p < .05/<.05).Conclusion.Pseudopodia and satellite tumors were more common than reported in the literature. If left in the surrounding salivary gland tissue at surgery, they can lead to recurrences of pleomorphic adenomas of the parotid gland. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Effects of cidofovir on a novel cell‐based test system for recurrent respiratory papillomatosis
Authors: Donne Adam J. , Hampson Lynne , He Xiao T. , Rothera Michael P. , Homer Jarrod J. , Hampson Ian N. 
Published: January 2007

AbstractBackground.Cidofovir has been reported to have activity against human papillomavirus (HPV) type 16, but no laboratory studies have been performed on HPV type 6, the main cause of recurrent respiratory papillomatosis (RRP).Methods.HPV6b E6 cDNA‐based C33A (non‐HPV cervical carcinoma) cell line was produced. Two different doses of cidofovir were applied to parent C33A, C33AT6E6, and C33AT16E6 (HPV 16). Growth and flow cytometry analysis were performed.Results.Polymerase chain reaction confirmed HPV6 E6 expression in C33AT6E6 cells. High‐dose cidofovir was found to be toxic to all cell lines. Low‐dose exposure was found to be toxic to C33AT16E6 cells at 3 days, whereas C33A and C33AT6E6 showed minimal toxicity at 6 days and earlier recovery following drug withdrawal.Conclusions.Cidofovir showed nonspecific toxicity against all 3 cell lines tested. HPV16 E6 expressing cells were more sensitive than parent or HPV6 E6 expressing cells. Cidofovir has no selective advantage for the RRP‐related HPV6 E6 expressing cell line. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Application of multivariate statistical procedures to the hydrochemical study of a coastal aquifer: an example from Crete, Greece
Authors: Papatheodorou G. , Lambrakis N. , Panagopoulos G. 
Published: January 2007

AbstractA variety of multivariate statistical procedures were applied to three separate sets of quantitative analytical data from a coastal aquifer located in Malia, Crete (Greece), in order to identify the major hydrochemical processes affecting the groundwater quality and to investigate the evolution of groundwater composition in three different sampling periods. Two of them were carried out on October 2001 and September 2002 at the end of the dry season and the third on April 2002 at the end of the wet period. Two factors were found that explained major hydrochemical processes in the aquifer. These factors reveal the existence of an intensive intrusion of seawater and mechanisms of nitrate contamination of groundwater. Bivariate plots of the scores of the two main factors showed that the seawater intrusion and nitrate pollution processes are maintained through three surveys and that the process of nitrate pollution increases from the first to the second dry survey. Q‐mode factor analysis and discriminant analysis of the three sampling periods clearly showed a seasonal variation of the whole chemistry of groundwater samples. This seasonal variation can be attributed to the freshwater recharge and seawater intrusion that affect the groundwater quality of the Malia aquifer. The results of trend surface analysis are in agreement with those of factor analysis. Moreover, the fourth‐order trend surfaces of EC, Cl− and NO3− showed that the salinization process is more intensive during the first dry period and the spatial variation of NO3− maxima plumes are strongly affected by the flow regime of the Malia aquifer. Copyright © 2007 John Wiley & Sons, Ltd.
What if the UK or Sweden had joined the euro in 1999? An empirical evaluation using a Global VAR
Authors: Hashem Pesaran M. , Vanessa Smith L. , Smith Ron P. 
Published: January 2007

AbstractThis paper attempts to provide a conceptual framework for the analysis of counterfactual scenarios using macroeconometric models. As an application we consider UK entry to the euro. Entry involves a long‐term commitment to restrict UK nominal exchange rates and interest rates to be the same as those of the euro area. We derive conditional probability distributions for the difference between the future realizations of variables of interest (e.g. UK and euro area output and prices) subject to UK entry restrictions being fully met over a given period and the alternative realizations without the restrictions. The robustness of the results can be evaluated by also conditioning on variables deemed to be invariant to UK entry, such as oil or US equity prices. Economic interdependence means that such policy evaluation must take account of international linkages and common factors that drive fluctuations across economies. In this paper this is accomplished using the Global VAR recently developed by Dees et al. (J. Appl. Econometrics, 2007, forthcoming). The paper briefly describes the GVAR which has been estimated for 25 countries and the euro area over the period 1979–2003. It reports probability estimates that output will be higher and prices lower in the UK and the euro area as a result of entry. It examines the sensitivity of these results to a variety of assumptions about when and how the UK entered and the observed global shocks and compares them with the effects of Swedish entry. Copyright © 2007 John Wiley & Sons, Ltd.
Differential effects of uniaxial and biaxial strain on U937 macrophage‐like cell morphology: Influence of extracellular matrix type proteins
Authors: Matheson Loren A. , Maksym Geoffrey N. , Santerre J. Paul , Labow Rosalind S. 
Published: January 2007

AbstractTissue engineering concepts have expanded in the last decade to consider the importance of biochemical signaling from extracellular matrix (ECM) proteins adhered to substrates such as polymeric and ceramic scaffolds. This study investigated combined ECM/mechanical factors on the key signaling cells (macrophages) for wound healing, since previously, mechanical strain and ECM proteins have only been considered separately for their effects on macrophage morphology. Human U937 macrophage‐like cells were cultured on a model elastomeric membrane, coated with either collagen type I or poly‐RGD peptide (ProNectin®). The cells were subjected to cyclic uniform uniaxial or nonuniform biaxial strain with the Flexercell™ Tension Plus system to simulate strains that various soft tissue implants may undergo during the critical tissue–implant integration period. The surface coatings affected total cellular protein, which was significantly higher in cells on collagen than ProNectin® coated surfaces after biaxial, but not uniaxial strain, whereas ProNectin® coated surfaces caused a decrease in DNA following uniaxial, but not biaxial strain. Adding the protein coatings that relate to the wound healing process during tissue regeneration, elicited effects specific to the strain type imposed. The combination of these parameters caused changes in U937 macrophage‐like cells that should be considered in the outcome of the desired performance in the tissue–material constructs. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Properties and molecular evolution of human GLUD2 (neural and testicular tissue‐specific) glutamate dehydrogenase
Authors: Kanavouras Konstantinos , Mastorodemos Vasileios , Borompokas Nikolas , Spanaki Cleanthe , Plaitakis Andreas 
Published: January 2007

AbstractGlutamate dehydrogenase (GDH) is an enzyme central to the metabolism of glutamate that also plays a role in cellular energetics. In the human, GDH exists in a housekeeping isoenzyme (hGDH1) encoded by the GLUD1 gene and a neural and testicular tissue‐specific isoform (hGDH2) encoded by the GLUD2 gene. There is evolutionary evidence that the GLUD1 was retroposed to the X chromosome in the ape ancestor (<23 million years ago), where it gave rise to GLUD2 through random mutations and directional selection. In the human, the two mature GDH isoproteins are highly homologous, differing in only 16 of their 505 amino acid residues. Functional analyses of highly purified recombinant wild‐type hGDH2 revealed that this adaptive evolution dissociated the enzyme from GTP control, permitted regulation almost entirely by ADP and/or L‐leucine, and fine‐tuned its activity to the relatively low cellular pH that occurs in synaptic astrocytes during excitatory transmission. Study of structure‐function relationships, using site‐directed mutagenesis of GLUD1 at single sites differing from GLUD2, showed that the Arg443Ser and the Gly456Ala change reproduced some, but not all, of the properties of hGDH2. In addition, we created a double hGDH1 mutant that had both Arg443Ser and Gly456Ala in the same polypeptide chain. Functional analyses revealed that the doubly mutated enzyme did not acquire all the characteristics of the wild‐type hGDH2. Hence, additional amino acid changes, acting in concert with Arg443Ser and Gly456Ala, ought to be responsible the unique properties of the brain‐specific human isoenzyme. © 2007 Wiley‐Liss, Inc.
Tephrabase: tephrochronology and the development of a centralised European database
Authors: Newton Anthony J. , Dugmore Andrew J. , Gittings Bruce M. 
Published: January 2007

AbstractTephrabase was launched on the World Wide Web in 1995 as a tool for tephrochronological research. In order to facilitate the identification, correlation and dating of tephra deposits, this database may be interrogated through multiple routes, including by source volcano, date, location, and tephra chemistry; datasets include stratigraphy, geochemistry, chronology and spatial information. Currently all the European data refer to Late Quaternary Icelandic‐sourced tephras, post‐12 k yr BP. The sites (62) where the tephra deposits are found include Iceland, the United Kingdom, Ireland, the Faroe Islands, Sweden and Russia. In addition, there are also data on tephra layers in central Mexico. Use of Tephrabase highlights the importance of selected geochemical data, but this has to be used with care as major element characteristics alone do not always produce unique definitions for single tephra deposits. For the most accurate results multiple criteria must be used. Tephrabase can be found at http://www.tephrabase.org. Copyright © 2007 John Wiley & Sons, Ltd.
The case for significant numbers of extraterrestrial impacts through the late Holocene
Authors: Baillie Mike 
Published: January 2007

AbstractWhen astronomers tell us that there should have been numerous impacts from space during the last five millennia, when impact craters exist on land and more impacts can be assumed over the oceans, why are historians, archaeologists and palaeoecologists not diligently seeking evidence for these impacts, and their effects? This article reviews just some of the relevant evidence for impacts. In turn this suggests that ablation material, background material from space, and micro‐tektites, should all be present in ocean cores, ice cores, peat, and lake sediments. It seems that almost no efforts have been made to find evidence that might link to the known crater fields, or to identify and date periods of enhanced cosmic activity. The question must be, why? Copyright © 2007 John Wiley & Sons, Ltd.