bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of Hydride Abstraction by Cyclopentadienone‐Ligated Carbonylmetal Complexes (M = Ru, Fe)
Authors: Thorson Megan K. , Klinkel Kortney L. , Wang Jianmei , Williams Travis J. 
Published: December 2008

AbstractCyclopentadienone‐ligated ruthenium complexes, such as Shvo's catalyst, are known to oxidize reversibly alcohols to the corresponding carbonyl compounds. The mechanism of this reaction has been the subject of some controversy, but it is generally believed to proceed through concerted transfer of proton and hydride, respectively, to the cyclopentadienone ligand and the ruthenium center. In this paper we further study the hydride transfer process as an example of a coordinatively directed hydride abstraction by adding quantitative understanding to some features of this mechanism that are not well understood. We find that an oxidant as weak as acetone can be used to re‐oxidize the intermediate ruthenium hydride without catalyst re‐oxidation becoming rate‐limiting. Furthermore, C–H cleavage is a significantly electrophilic event, as demonstrated by a Hammett reaction parameter of ρ = –0.89. We then describe how the application of our mechanistic insights obtained from the study have enabled us to extend the ligand‐directed hydride abstraction strategy to include a rare example of an iron(0) oxidation catalyst.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Enantioselective Synthesis of Functionalized 1‐Benzoxepines by Phenoxide Ion Mediated 7‐endo‐tet Carbocyclization of Cyclic Sulfates
Authors: Das Sajal Kumar , Dinda Subal Kumar , Panda Gautam 
Published: December 2008

AbstractA new asymmetric synthesis of 2,3‐disubstituted 1‐benzoxepines is described. Key steps include Sharpless asymmetricdihydroxylation of trans‐α,β‐unsaturated esters and phenoxide ion mediated intramolecular 7‐endo‐tet carbocyclization of syn‐2,3‐dihydroxy ester derived cyclic sulfates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Instabilities of Boussinesq models in non‐uniform depth
Authors: Løvholt F. , Pedersen G. 
Published: December 2008

AbstractThe von Neumann method for stability analysis of linear waves in a uniform medium is a widely applied procedure. However, the method does not apply to stability of linear waves in a variable medium. Herein we describe instabilities due to variable depth for different Boussinesq equations, including the standard model by Peregrine and the popular generalization by Nwogu. Eigenmodes are first found for bathymetric features on the grid scale. For certain combinations of Boussinesq formulations and bottom profiles stability limits are found in closed form, otherwise numerical techniques are used for the eigenvalue problems. Naturally, the unstable modes in such settings must be considered to be as much a result of the difference method as of the underlying differential (Boussinesq) equations. Hence, modes are also computed for smooth depth profiles that are well resolved. Generally, the instabilities do not vanish with refined resolution. In some cases convergence is observed and we thus have indications of unstable solutions of the differential equations themselves. The stability properties differ strongly. While the standard Boussinesq equations seem perfectly stable, all the other formulations do display unstable modes. In most cases the instabilities are linked to steep bottom gradients and small grid increments. However, while a certain formulation, based on velocity potentials, is very prone to instability, the Boussinesq equations of Nwogu become unstable only under quite demanding conditions. Still, for the formulation of Nwogu, instabilities are probably inherent in the differential equations and are not a result of the numerical model. Copyright © 2008 John Wiley & Sons, Ltd.
Variable selection and oversampling in the use of smooth support vector machines for predicting the default risk of companies
Authors: Härdle Wolfgang , Lee Yuh‐Jye , Schäfer Dorothea , Yeh Yi‐Ren 
Published: December 2008

AbstractIn the era of Basel II a powerful tool for bankruptcy prognosis is vital for banks. The tool must be precise but also easily adaptable to the bank's objectives regarding the relation of false acceptances (Type I error) and false rejections (Type II error). We explore the suitability of smooth support vector machines (SSVM), and investigate how important factors such as the selection of appropriate accounting ratios (predictors), length of training period and structure of the training sample influence the precision of prediction. Moreover, we show that oversampling can be employed to control the trade‐off between error types, and we compare SSVM with both logistic and discriminant analysis. Finally, we illustrate graphically how different models can be used jointly to support the decision‐making process of loan officers. Copyright © 2008 John Wiley & Sons, Ltd.
Mortality forecasting using neural networks and an application to cause‐specific data for insurance purposes
Authors: Shah Paras , Guez Allon 
Published: December 2008

AbstractMortality forecasting is important for life insurance policies, as well as in other areas. Current techniques for forecasting mortality in the USA involve the use of the Lee–Carter model, which is primarily used without regard to cause. A method for forecasting morality is proposed which involves the use of neural networks. A comparative analysis is done between the Lee–Carter model, linear trend and the proposed method. The results confirm that the use of neural networks performs better than the Lee–Carter and linear trend model within 5% error. Furthermore, mortality rates and life expectancy were formulated for individuals with a specific cause based on prevalence data. The rates are broken down further into respective stages (cancer) based on the individual's diagnosis. Therefore, this approach allows life expectancy to be calculated based on an individual's state of health. Copyright © 2008 John Wiley & Sons, Ltd.
Distinctive expression and function of four GSDM family genes (GSDMA‐D) in normal and malignant upper gastrointestinal epithelium
Authors: Saeki Norihisa , Usui Takebumi , Aoyagi Kazuhiko , Kim Dal Ho , Sato Megumi , Mabuchi Tomoko , Yanagihara Kazuyoshi , Ogawa Kenji , Sakamoto Hiromi , Yoshida Teruhiko , Sasaki Hiroki 
Published: December 2008

AbstractGasdermin (GSDM or GSDMA), expressed in the upper gastrointestinal tract but frequently silenced in gastric cancers (GCs), regulates apoptosis of the gastric epithelium. It has three human homologs, GSDMB, GSDMC, and GSDMD (GSDM family) and they are considered to be involved in the regulation of epithelial apoptosis but not yet known. We investigated the expression pattern of the family genes in the upper gastrointestinal epithelium and cancers. Reverse transcriptase‐polymerase chain reaction revealed that, unlike GSDMA expressed in differentiated cells, GSDMB is expressed in proliferating cells and GSDMD in differentiating cells. GSDMC, meanwhile, is expressed in both differentiating and differentiated cells. Colony formation assay showed that GSDMB, closely related to GSDMA, has no cell‐growth inhibition activity in gastric cancer cells, and that GSDMC and GSDMD, respectively, exhibit the activity with different strengths from that of GSDMA. Expression analyses of the four family genes in esophageal and GCs suggested that GSDMC and GSDMD as well as GSDMA are tumor suppressors and that GSDMB, which was amplified and overexpressed in some GCs, could be an oncogene. The results of the expression analysis and colony formation assay suggest that each family gene may have a distinct function in the upper gastrointestinal epithelium. © 2008 Wiley‐Liss, Inc.
Promoter methylation blocks FES protein‐tyrosine kinase gene expression in colorectal cancer
Authors: Shaffer Jonathan M. , Smithgall Thomas E. 
Published: December 2008

AbstractThe FES locus encodes a unique nonreceptor protein‐tyrosine kinase (FES) traditionally viewed as a proto‐oncogene but more recently implicated as a tumor suppressor in colorectal cancer (CRC). Recent studies have demonstrated that while FES is expressed in normal colonic epithelium, expression is lost in tumor tissue and colorectal cancer cell lines, a finding common among tumor suppressors. Here we provide compelling evidence that promoter methylation is an important mechanism responsible for downregulation of FES gene expression in colorectal cancer cells. Treatment with the DNA methyltransferase inhibitor 5‐aza‐2′‐deoxycytidine resulted in the expression of functional FES transcripts in all CRC cell lines examined, including Caco‐2, COLO 320, DLD‐1, HCT 116, SNU‐1040, SW‐480, and HT‐29. Bisulfite sequencing of genomic DNA isolated from 5‐aza‐2′‐deoxycytidine‐treated HT‐29 cells identified methylated CpG dinucleotides immediately upstream from the FES transcription initiation sites. In contrast, this region of the FES promoter was hypomethylated in genomic DNA from normal colonic epithelium. In addition, methylation completely blocked the activity of the FES promoter in reporter gene assays. Promoter methylation is a previously unrecognized mechanism by which FES expression is suppressed in CRC cell lines, and is consistent with a tumor suppressor role for FES in this tumor site despite its tyrosine kinase activity. © 2008 Wiley‐Liss, Inc.
Expression of distinct splice variants of the stem cell marker prominin‐1 (CD133) in glial cells
Authors: Corbeil Denis , Joester Angret , Fargeas Christine A. , Jászai József , Garwood Jeremy , Hellwig Andrea , Werner Hauke B. , Huttner Wieland B. 
Published: December 2008

AbstractProminin‐1 (CD133) is a cholesterol‐interacting pentaspan membrane glycoprotein specifically associated with plasma membrane protrusions. Prominin‐1 is expressed by various stem and progenitor cells, notably neuroepithelial progenitors found in the developing embryonic brain. Here, we further investigated its expression in the murine brain. Biochemical analyses of brain membranes at early stages of development revealed the expression of two distinct splice variants of prominin‐1, s1 and s3, which have different cytoplasmic C‐terminal domains. The relative abundance of the s3 variant increased toward adulthood, whereas the opposite was observed for the s1 variant. Our combined in situ hybridization and immunohistochemistry revealed the expression of prominin‐1 in a subpopulation of Olig‐2‐positive oligodendroglial cells present within white matter tracts of postnatal and adult brain. Furthermore, immunohistological and biochemical characterization suggested strongly that the s3 variant is a novel component of myelin. Consistent with this, the expression of prominin‐1.s3 was significantly reduced in the brain of myelin‐deficient mice. Finally, oligodendrocytes expressed selectively the s3 variant whereas GFAP‐positive astrocytes expressed the s1 variant in primary glial cell cultures derived from embryonic brains. Collectively, our data demonstrate a complex expression pattern of prominin‐1 molecules in developing adult brain. Given that prominin‐1 is thought to act as an organizer of plasma membrane protrusions, they further suggest that a specific prominin‐1 splice variant might play a role in morphogenesis and/or maintenance of the myelin sheath. © 2008 Wiley‐Liss, Inc.
Ammonium‐evoked alterations in intracellular sodium and pH reduce glial glutamate transport activity
Authors: Kelly Tony , Kafitz Karl W. , Roderigo Claudia , Rose Christine R. 
Published: December 2008

AbstractThe clearance of extracellular glutamate is mainly mediated by pH‐ and sodium‐dependent transport into astrocytes. During hepatic encephalopathy (HE), however, elevated extracellular glutamate concentrations are observed. The primary candidate responsible for the toxic effects observed during HE is ammonium (NH4+/NH3). Here, we examined the effects of NH4+/NH3on steady‐state intracellular pH (pHi) and sodium concentration ([Na+]i) in cultured astrocytes in two different age groups. Moreover, we assessed the influence of NH4+/NH3on glutamate transporter activity by measuringD‐aspartate‐induced pHiand [Na+]itransients. In 20–34 daysin vitro(DIV) astrocytes, NH4+/NH3decreased steady‐state pHiby 0.19 pH units and increased [Na+]iby 21 mM.D‐Aspartate‐induced pHiand [Na+]itransients were reduced by 80–90% in the presence of NH4+/NH3, indicating a dramatic reduction of glutamate uptake activity. In 9–16 DIV astrocytes, in contrast, pHiand [Na+]iwere minimally affected by NH4+/NH3, andD‐aspartate‐induced pHiand [Na+]itransients were reduced by only 30–40%. Next we determined the contribution of Na+, K+, Cl−‐cotransport (NKCC). Immunocytochemical stainings indicated an increased expression of NKCC1 in 20–34 DIV astrocytes. Moreover, inhibition of NKCC with bumetanide prevented NH4+/NH3‐evoked changes in steady‐state pHiand [Na+]iand attenuated the reduction ofD‐aspartate‐induced pHiand [Na+]itransients by NH4+/NH3to 30% in 20–34 DIV astrocytes. Our results suggest that NH4+/NH3decreases steady‐state pHiand increases steady‐state [Na+]iin astrocytes by an age‐dependent activation of NKCC. These NH4+/NH3‐evoked changes in the transmembrane pH and sodium gradients directly reduce glutamate transport activity, and may, thus, contribute to elevated extracellular glutamate levels observed during HE. © 2008 Wiley‐Liss, Inc.
Neuropsychiatric profiles of patients with Alzheimer's disease and vascular dementia in Taiwan
Authors: Hsieh Chia‐Jung , Chang Chia‐Chi , Lin Chia‐Chin 
Published: December 2008

AbstractBackgroundPrevious studies have reported several conflicting findings regarding neuropsychiatric symptoms when comparing patients with Alzheimer's disease (AD) and patients with vascular dementia (VaD).ObjectivesThe purpose was to: (1) compare the prevalence of neuropsychiatric symptoms among patients with AD and VaD after controlling for demographic characteristics in difference setting and (2) rank and contrast the severity the common symptoms between the two groups in north of Taiwan.MethodsThis study was a cross‐sectional comparative design. Data were collected from clinical interviews using three instruments: the Mini‐Mental Status Examination (MMSE), the Clinical Dementia Rating Scale (CDR), and the Neuropsychiatric Inventory (NPI).ResultsA total of 154 subjects participated in this study. The male subjects with VaD from the outpatient setting had lower NPI scores. In the OPD, the subjects with AD had more nighttime behavior than subjects with VAD. In the nursing home setting, the subjects with VaD had higher prevalence of depression, irritability, and appetite changes than subjects with AD. The subjects with AD had more euphoria and nighttime behavior than subjects with VaD. The average of total NPI scores for people with AD and VaD from the nursing home setting indicate higher scores. In the nursing home group, the VaD subjects evidenced significantly higher irritability scores than the AD subjects.ConclusionsThis was first care unit based study in north Taiwan. Our results showed the significant differences between AD and VaD groups of NPI symptoms. Understanding those differences may aid differential diagnosis of dementia subtypes and help develop proper interventions. Copyright © 2008 John Wiley & Sons, Ltd.
Evolution of stimulants to treat ADHD: transdermal methylphenidate
Authors: Patrick Kennerly S. , Straughn Arthur B. , Perkins Jeb S. , González Mario A. 
Published: December 2008

AbstractObjectiveThe following comprehensive review describes the evolution of stimulant drug formulations used in the treatment of attention‐deficit/hyperactivity disorder (ADHD). Emphasis is placed on the basic and clinical pharmacology of the dl‐methylphenidate (MPH) transdermal system (MTS).MethodsThe pharmacokinetic and pharmacodynamic literature pertaining to MPH and amphetamine enantiomers was reviewed in the context of ADHD therapy and MTS as a treatment option.ResultsMTS incorporates MPH into an adhesive monolithic matrix, using the free base form of the drug to facilitate transdermal absorption. MTS technology minimizes contact dermatitis by eliminating to need for percutaneous penetration enhancers. After a lag time of approximately 2 h, plasma concentrations of the therapeutic d‐MPH isomer become detectable, then continuously rise over the course of the recommended 9 h wear time. Concentrations of l‐MPH typically attain 40–50% that of d‐MPH (vs. 1–2% following oral MPH). Unauthorized MTS removal poses some misuse liability and over 50% of MTS drug content remains in the discarded system.ConclusionsWhile liquid or chewable MPH formulations overcome potential swallowing difficulties, as do sprinkled once‐daily extended‐release (ER) MPH products, only MTS addresses swallowing difficulties while also offering a flexible individualized MPH exposure time in a once‐daily MPH regimen. Copyright © 2008 John Wiley & Sons, Ltd.
Molecular determinants of efficacy for 5‐FU‐based treatments in advanced colorectal cancer: mRNA expression for 18 chemotherapy‐related genes
Authors: Gustavsson Bengt , Kaiser Christopher , Carlsson Göran , Wettergren Yvonne , Odin Elisabeth , Lindskog Elinor Bexe , Niyikiza Clet , Ma Doreen 
Published: December 2008

Abstract5‐Fluorouracil (5‐FU)‐based regimens remain a cornerstone in the treatment of colorectal cancer (CRC). However, the attendant toxicity prevents these regimens from reaching maximum therapeutic potential. In this retrospective analysis, we examined the pretreatment expression of 18 genes in archival tumor bank samples from patients with advanced CRC to determine if one or more of the selected genes showed promise as either a prognostic or predictive marker of 5‐FU‐based treatment outcomes. One hundred and forty‐four CRC patient samples (collected from 1983 to 2004) were analyzed via real‐time PCR for gene expression. Univariate analyses were used to correlate gene expression with efficacy and time‐to‐event variables. Low thymidine phosphorylase (TP), dihydrofolate reductase, dihydropyrimidine dehydrogenase (DPD), excision repair cross‐complementing 1 (ERCC1) and thymidylate synthase gene expression were associated with better time‐to‐progression in the entire population. Low TP, DPD and ERCC1 expression were independently associated with improved overall survival. Low TP gene expression was also predictive of response. This study suggests that TP gene expression in particular is a predictive as well as a prognostic biomarker for advanced CRC patients. Gene panels assessing pretreatment TP, DPD, ERCC1, dihydrofolate reductase and thymidylate synthase gene expression may help improve the therapeutic potential of 5‐FU‐ or other novel antifolate‐based regimens. Further analysis of the prognostic or predictive value of these genes in prospective trials in CRC patients seems warranted. © 2008 Wiley‐Liss, Inc.
Binary choice under social interactions: an empirical study with and without subjective data on expectations
Authors: Li Ji , Lee Lung‐fei 
Published: December 2008

AbstractThis paper examines two methods of modeling binary choice with social interactions: models assuming homogeneous rational expectations and models using subjective data on expectations. Exploiting a unique survey conducted during the 1996 US presidential election that was designed to study voting behavior under social context, we find that in various model specifications using subjective expectations consistently improves models' goodness‐of‐fit; and that subjective expectations are not rational as formulated by Brock and Durlauf. Specifically, members' characteristics are individually important in forming expectations. We also include correlated effect in the rational expectation model. This extension provides a remedy to the selection issues that often arise in social interaction models. Copyright © 2008 John Wiley & Sons, Ltd.
Monocyte inflammatory and matrix remodeling response modulated by grafted ECM‐derived ligand concentration
Authors: Chung Amy S. , Waldeck Heather , Schmidt David R. , Kao Weiyuan John 
Published: December 2008

AbstractLigands presented on biomaterials are a common method to facilitate and control the host response. In a gelatin and polyethylene glycol diacrylate (PEGdA) based semi‐interpenetrating network (sIPN), the effects of extracellular matrix (ECM)‐derived peptide amount on monocyte adhesion and subsequent protein and mRNA expression were examined. Peptide amount on the sIPN surface was controlled by varying the wt % ratio of the peptide‐PEG grafted gelatin to PEGdA. We hypothesized that increasing bioactive peptide amount would modulate human blood‐derived monocyte adhesion, cytokine expression, and gene regulation. Monocyte adhesion, release of gelatin degrading proteases matrix metalloprotease‐2 (MMP‐2), matrix metalloprotease‐9 (MMP‐9), and proinflammatory protein interleukin‐1β (IL‐1β), and mRNA expression of these proteins were evaluated. We found RGD‐PEG grafted sIPNs with higher surface RGD concentrations showed increased adherent density. MMP‐2 and IL‐1β protein release was also influenced by the ligand concentration, as initial increase in protein concentration was observed at higher ligand concentrations. MMP‐9 protein showed an initial increase that subsided then increased. A decreased IL‐1β protein and mRNA expression was observed over time but MMP‐2 mRNA was not detected at any time though MMP‐2 protein concentrations showed an initial burst. Hence, monocyte behavior was modulated by surface ligand identity in tandem with ligand concentration. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Potential use of mucins as biomaterial coatings. I. Fractionation, characterization, and model adsorption of bovine, porcine, and human mucins
Authors: Sandberg Tomas , Blom Hans , Caldwell Karin D. 
Published: December 2008

AbstractPreviously, we presented evidence that mucins have potential as biomaterial coatings. Here, we reveal substantial batch‐to‐batch variations for a frequently used commercial bovine salivary mucin preparation (BSM) and stress the importance of standardizing mucins intended for comparative purposes. “Mild” fractionation strategies, aiming at preserving natural mucin functions, were used to prepare two more defined BSM fractions as well as three mucin fractions from porcine gastric (PGM) and human salivary (MG1) sources. While the BSM and PGM were highly purified and mainly adopted random coil conformations in solution, the MG1 contained mucin‐bound components (1.6 wt% albumin) and appeared compact. Average molar masses and root‐mean‐square radii for the predominant BSM, PGM, and MG1 species spanned 0.8–4.2 MDa and 46–86 nm, respectively. An ellipsometric evaluation, using hydrophilic and hydrophobic silica, showed the mucin adsorption to be slow and related to mucin charge, size, conformation, and compositional complexity. The mass uptakes on hydrophobic silica averaged 2.6, 2.6, and 5.0 mg/m2, for BSM, PGM, and MG1, respectively. Finally, we find that stable mucin coatings can be formed on polymers of different wettability. The reported mucin preparations serve as platforms for a series of studies on the biocompatibility of mucin coatings. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009