bluuebunny/crossref_metadata_2025_split huggingface dataset:
Facile Access to Homo‐ and Heteroleptic, Triply Bonded Dimolybdenum Hexaalkoxides with Unsaturated Alkoxide Ligands
Authors: Krackl Sebastian , Ma Jian‐Gong , Aksu Yilmaz , Driess Matthias 
Published: February 2011

AbstractA series of monodentate, triply bonded Mo2(OR)6 complexes [R = MBE (1) (MBE = 2‐methylbut‐3‐ene‐2‐yl), MMP (2) (MMP = 1‐methoxy‐2‐methylpropane‐2‐yl), Terp (3) [Terp = 2‐(4‐methylcyclohex‐3‐enyl)propane‐2‐yl], which exhibit C–C double bonds or an ether function in the ligand sphere, were synthesized and characterized by multinuclear (1H, 13C and 95Mo) NMR studies. The partial alcoholysis of the latter complexes with neopentyl alcohol (neopentOH) led to the heteroleptic alkoxides Mo2(OR)n(Oneopent)6–n (4–7) {n = 2 [for R = tBu (4), MBE (5), MMP (6)], 4 [for R = Terp (7)]}. This concept was further applied to the synthesis of Mo2(O2DMH)2(OtBu)2 (8) (DMH = 2,5 dimethylhexyl) by starting from the Mo2(OtBu)6 precursor. The 1H NMR spectra for the heteroleptic complexes 4–8 show signals that are significantly shifted to a higher field for the RO ligand protons compared to those of their homoleptic analogues. This is the result of a change in the spatial position of the alkoxide ligands (RO) in the homoleptic compared to the heteroleptic complexes that leads to a different magnetic environment for the alkoxide ligands due to the magnetic anisotropy of the Mo–Mo triple bond. 95Mo NMR studies of the complexes 1–8 show that the resonance strongly depends on the substitution pattern of the alkoxide and that a shift to higher field is observed when going from the tertiary to the primary alkoxides. The molecular structures for 4–8 were determined by single‐crystal X‐ray diffraction, and all of the complexes show a staggered conformation as well as an asymmetric ligand distribution, which results in unequal Mo–O bond lengths. For the heteroleptic complexes 4–7, the RO ligands (R = tBu, MBE, MMP and Terp, respectively) exhibit the longest bond lengths, which suggests that the position of the ligand strongly depends on the steric congestion of the α‐carbon atom of the alkoxide ligand. In 6, the methoxy function enables an intramolecular O→Mo coordination as is indicated by a Mo–O distance of 2.2464(7) Å. This fact is supported by a lengthening of the Mo–Mo triple bond.
Tandem 1,5‐Hydride Shift/6π Electrocyclization of Ketenimines and Carbodiimides Substituted with Cyclic Acetal and Dithioacetal Functions: Experiments and Computations
Authors: Alajarin Mateo , Bonillo Baltasar , Ortin Maria‐Mar , Sanchez‐Andrada Pilar , Vidal Angel 
Published: February 2011

AbstractN‐Aryl ketenimines bearing five‐ and six‐membered cyclic acetal functions – such as 1,3‐dioxolane, 1,3‐dithiolane, 1,3‐dioxane, and 1,3‐dithiane systems – at the ortho position of the N‐aryl substituent transform on mild thermal treatment into quinolines, through a tandem sequence consisting of a [1,5]‐H shift followed by a 6π electrocyclic ring closure. Structurally analogous N‐aryl carbodiimides are converted into quinazolines in comparable tandem processes. Similar sequences can be successfully applied to N‐thienyl and N‐pyrazolyl ketenimines. DFT calculations have established a two‐step mechanism for those conversions, consisting of an initial 1,5‐hydride shift and subsequent 6π electrocyclization, and confirm the beneficial effect of the acetal function, which gives hydride character to the migrating hydrogen atom. The capability to promote the H shift depends on the type of acetal function (acetal better than dithioacetal), its ring size (five‐membered better than six‐membered) and the heterocumulenic fragment (ketenimine better than carbodiimide). Changing the benzene ring connecting the acetal and ketenimine functions for a heterocyclic ring has pronounced consequences for the magnitude of the energy barriers.
Studies towards the Synthesis of Pentalenene: Mechanistic Insights into the Isomerization Phenomenon During RCM of Medium‐Sized Rings
Authors: De Bo Guillaume , Markó István E. 
Published: February 2011

AbstractIsomerization issues have been encountered during the ring‐closing metathesis (RCM) step of a new approach towards pentalenene. This paper describes the mechanistic insights gained during the study of this side reaction from a substrate perspective. Isomerization issues have been encountered during the RCM step of a new approach towards pentalenene.
Betti Reaction of Cyclic Imines with Naphthols and Phenols – Preparation of New Derivatives of Betti's Bases
Authors: Cimarelli Cristina , Fratoni Davide , Mazzanti Andrea , Palmieri Gianni 
Published: February 2011

AbstractA large library of aminocycloalkylphenols and ‐naphthols is obtained by the Betti reaction between activated phenols and naphthols and five‐ and six‐membered cyclic imines. Due to the formation of an intramolecular hydrogen bond in the transition state, the attack takes place regioselectively at the position adjacent to the hydroxy group of the aromatic compounds. X‐ray crystallography and chirooptical methods (electronic circular dichroism) were used to ascertain the absolute configuration of two aminoalkylnaphthols obtained, after resolution of the corresponding racemates with (R,R)‐tartaric acid. In addition, some aminoalkylnaphthols and‐phenols were alkylated at the nitrogen atom to obtain N‐methylated products in good yields.
A General, Diastereoselective Synthesis of Highly Functionalized Bicyclo[n.3.1]alkane Systems Based on an Anionic Domino Reaction of α‐Nitrocycloalkanones
Authors: Giorgi Giorgio , Miranda Sonia , Ruiz Miriam , Rodriguez Jean , López‐Alvarado Pilar , Menéndez J. Carlos 
Published: February 2011

AbstractThe base‐promoted Michael–aldol anionic domino reactions of cyclic α‐nitro ketones and α,β‐unsaturated aldehydes afforded bicyclo[n.3.1]alkanone systems of seven different ring sizes (n = 3–9), normally in excellent yields. This can be considered the first general method for the synthesis of this type of carbocycle. Furthermore, up to four stereocentres are generated, three of which are contiguous and include a functionalized quaternary bridgehead carbon atom. The diastereoselectivity was often complete, was much higher than in less general reactions based on related domino processes, and involved the generation of a different major diastereomer due to the control of the Michael and aldol individual steps of the reaction by the nitro group.
Diastereoselective Synthesis of Lincosamine Precursors
Authors: Serra Fiona , Coutrot Philippe , Estève‐Quelquejeu Mélanie , Herson Patrick , Olszewski Tomasz K. , Grison Claude 
Published: February 2011

AbstractThe stereoselective syntheses of the four aminodiol precursors of the diastereomers of lincosamine are reported. The procedure is based on the initial two‐carbon elongationof 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galactohexodialdo‐1,5‐pyranose, followed by the stereocontrolled introduction of the amino group by nucleophilic amination. Two complementary approaches have been investigated and compared: The first one is the direct transformation of α‐chloroglycidic ester into β‐amino‐α‐keto ester. The second strategy is a three‐step synthesis that is based on the treatment of the β‐iodo‐α‐keto ester with dibenzylamine. Subsequent reduction of the β‐amino‐α‐keto ester provides the pure D‐erythro, L‐threo, L‐erythro, and D‐threo aminodiols after chromatographic purification. Further classical transformations afford the N‐acetyl derivatives, which are key precursors of the lincosamine diastereomers.
Gold nanoparticles deposited capillaries for in‐capillary microextraction capillary zone electrophoresis of monohydroxy‐polycyclic aromatic hydrocarbons
Authors: Wang Huiyong , Knobel Gaston , Wilson Walter B. , Calimag‐Williams Korina , Campiglia Andres D. 
Published: February 2011

AbstractThis article presents the first application of gold nanoparticles deposited capillaries as pre‐concentration devices for in‐capillary microextraction CZE and their use for the analysis of monohydroxy‐polycyclic aromatic hydrocarbons in synthetic urine samples. The successful separation of 1‐hydroxypyrene, 9‐hydroxyphenanthrene, 3‐hydroxybenzo[a]pyrene (3‐OHbap), 4‐hydroxybenzo[a]pyrene and 5‐hydroxybenzo[a]pyrene under a single set of electrophoretic conditions is demonstrated as well as the feasibility to obtain competitive ultraviolet absorption LOD with commercial instrumentation. Enrichment factors ranging from 87 (9‐OHphe) to 100 (3‐OHbap) made it possible to obtain LOD ranging from 9 ng/mL (9‐OHphe and 3‐OHbap) to 14 ng/mL (4‐hydroxybenzo[a]pyrene).
Return of the Trojan horse: intracellular phenotype switching and immune evasion by Staphylococcus aureus
Authors: Garzoni Christian , Kelley William L. 
Published: February 2011

AbstractStaphylococcus aureus small colony variants (SCVs), which are characterized by slow growth and a range of morphological and metabolic changes including altered antibiotic resistance profiles, have been studied for several decades. This Closeup highlights findings described in this issue of EMBO Molecular Medicine by Tuchscherr et al (2011), who present strong evidence that SCVs can arise in chronic infection models when S. aureus is internalized in non‐professional phagocytes and survives intracellularly. As the intracellular residency time increases, the proportion of SCVs grows and the host cell inflammatory response diminishes. The study suggests that this mode of phenotype switching is an essential feature of the S. aureus infection process and can explain an underlying cause of chronic and relapsing infections.See related article in EMBO Mol Med (Tuchscherr et al (2011) EMBO Mol Med 3: 129‐141)
Interlaboratory comparison of measurements of acid-volatile sulfide and simultaneously extracted nickel in spiked sediments
Authors: Brumbaugh William G , Hammerschmidt Chad R , Zanella Luciana , Rogevich Emily , Salata Gregory , Bolek Radoslaw 
Published: February 2011

Abstract
An interlaboratory comparison of acid-volatile sulfide (AVS) and simultaneously extracted nickel (SEM_Ni) measurements of sediments was conducted among five independent laboratories. Relative standard deviations for the seven test samples ranged from 5.6 to 71% (mean = 25%) for AVS and from 5.5 to 15% (mean = 10%) for SEM_Ni. These results are in stark contrast to a recently published study that indicated AVS and SEM analyses were highly variable among laboratories. Environ. Toxicol. Chem. 2011; 30:1306–1309. © 2011 SETAC
Development of a microarray for Enchytraeus albidus (Oligochaeta): preliminary tool with diverse applications
Authors: Amorim Mónica J.B , Novais Sara C , Van Der Ven Karlijn , Vandenbrouck Tine , Soares Amadeu M.V.M , De Coen Wim 
Published: February 2011

Abstract
Standard bioassays allow hazard assessment at the population level, but much remains to be learned about the molecular level response of organisms to stressors. The main aim of this study was the development of a DNA microarray for Enchytraeus albidus, a common soil worm species. Further, this microarray was tested using worms exposed to Cu, phenmedipham, and different soil types. Hybridization onto the developed microarray revealed several genes with homology to known sequences. Genes of interest were confirmed through real-time polymerase chain reaction. It was possible to discriminate between natural and chemical stressors and chemical concentrations. Gene responses were detected under conditions known to have effects in the reproduction of individuals. It was confirmed that the integration of different endpoints improves the assessment process and enhances the understanding of the modes of action of stressors. The chemical stress-induced genes were related to factors such as immune response, stress response, metabolic processes, and/or signal transduction. The present study represents the first step of a gene-level study in the ecologically relevant and standard test species E. albidus. It demonstrates the usefulness of cDNA normalization in the production of cDNA libraries of ecotoxicological standard organisms that are not genome models like E. albidus. Environ. Toxicol. Chem. 2011; 30:1395–1402. © 2011 SETAC
A Single Layer Glucose Fuel Cell Intended as Power Supplying Coating for Medical Implants
Authors: Kloke A. , Biller B. , Kräling U. , Kerzenmacher S. , Zengerle R. , von Stetten F. 
Published: February 2011

AbstractWe present a novel type of abiotically catalysed implantable glucose fuel cell with anode and cathode placed side by side, using a Raney‐platinum glucose oxidation anode with high tolerance towards oxygen. In contrast to conventional assembly designs used for implantable glucose fuel cells, no permeable cathode mounted in front of the anode to effect oxygen depletion is required. At 2.2 ± 0.1 μW cm–2 the single layer fuel cell exhibits only half the maximum power density of the conventional fuel cell, which solely stems from the doubled total fuel cell area demand. Nevertheless, the novel single layer design is advantageous in terms of simplified fabrication and reduced overall thickness, facilitating implementation of the fuel cell as a power supplying coating directly on the surface of medical implants. Furthermore, the single layer design offers an attractive possibility to diminish the reduction of power density by limited oxygen mass transfer to the cathode by increasing the cathode to anode area proportion. With doubled cathode area proportion a by 36% higher power density can be reached. To calculate the optimum cathode to anode area proportions, we introduced an analytical model based on the experimentally determined polarisation resistances of the individual electrodes.
Signal transduction inhibitors and antiangiogenic therapies for malignant glioma
Authors: Mellinghoff Ingo K. , Lassman Andrew B. , Wen Patrick Y. 
Published: February 2011

AbstractDetailed characterization of the cancer genome in a large number of primary human glioblastomas has identified recurrent alterations that result in deregulation of signal transduction pathways and are “druggable” with a growing number of small molecule pharmaceuticals. While many of these compounds have shown clinical activity in other human cancers harboring similar genetic alterations, the clinical experience in glioblastoma has been disappointing thus far with only rare and transient radiographic responses. Our understanding of drug resistance is confounded by the uncertainty of drug delivery across the blood brain barrier and the limited knowledge to what extent the growth of these tumors depends on any particular signaling pathway. This uncertainty is, at least in part, due to shortcomings in the current approach to evaluate signal transduction inhibitors in glioma patients, including drug testing in molecularly unselected patient populations, limited documentation of drug penetration and target inhibition in tumor tissue, and use of radiographic response criteria that may not be optimal for the evaluation of these compounds. © 2011 Wiley‐Liss, Inc.
Schwann cell plasticity after spinal cord injury shown by neural crest lineage tracing
Authors: Nagoshi Narihito , Shibata Shinsuke , Hamanoue Makoto , Mabuchi Yo , Matsuzaki Yumi , Toyama Yoshiaki , Nakamura Masaya , Okano Hideyuki 
Published: February 2011

AbstractAfter spinal cord injury (SCI), various cell types are recruited to the lesion site, including Schwann cells, which originate in the neural crest and normally myelinate axons in the peripheral nervous system. Here, we investigated the differentiation states, migration patterns, and roles of neural crest derivatives following SCI, using two transgenic mouse lines carrying neural crest‐specific reporters, P0‐Cre/Floxed‐EGFP and Wnt1‐Cre/Floxed‐EGFP. In these mice, EGFP is expressed only in the neural crest cell lineage. Immunohistochemical analysis revealed that most of the EGFP+ cells that infiltrated the lesion site after SCI were Schwann cells. Seven days after SCI, the P0‐positive, mature Schwann cells residing at the nerve roots had dedifferentiated into P0−/p75+ immature Schwann cells, which proliferated and began migrating into the lesion site. The dedifferentiation of the Schwann cells was corroborated by their expression of phosphorylated c‐Jun, which promotes dedifferentiation and inhibits the expression of myelin‐associated genes in the peripheral nerves. Thereafter, the number of EGFP+/p75+ immature Schwann cells decreased and that of EGFP+/P0+ mature cells increased gradually, indicating that the cells redifferentiated into mature Schwann cells within the lesion site. This study draws on the advantages offered by transgenic mouse lines bearing a genetic cell‐lineage marker and extends previous work by describing the origins and behavior of the neural crest‐derived cells that contribute to endogenous repair after SCI. This process, involving Schwann cell plasticity, is a novel repair mechanism for the lesioned mammalian spinal cord. © 2011 Wiley‐Liss, Inc.
NG2 cells are not a major source of reactive astrocytes after neocortical stab wound injury
Authors: Komitova Mila , Serwanski David R. , Richard Lu Q. , Nishiyama Akiko 
Published: February 2011

AbstractNG2 cells are an abundant glial cell type in the adult brain. They are distinct from astrocytes, mature oligodendrocytes, and microglia. NG2 cells generate oligodendrocytes and a subpopulation of protoplasmic astrocytes in the ventral forebrain during development. To determine whether NG2 cells generate reactive astrocytes in the lesioned brain, stab wound injury was created in adult NG2creBAC:ZEG double transgenic mice, in which enhanced green fluorescent protein (EGFP) is expressed in NG2 cells and their progeny, and the phenotype of the EGFP+ cells was analyzed at 10 and 30 days post lesion (dpl). The majority (>90%) of the reactive astrocytes surrounding the lesion that expressed glial fibrillary acidic protein (GFAP) lacked EGFP expression, and conversely the majority (>90%) of EGFP+ cells were GFAP‐negative. However, 8% of EGFP+ cells co‐expressed GFAP at 10 dpl. Most of these EGFP+GFAP+ cells were morphologically distinct from hypertrophic reactive astrocytes and exhibited weak GFAP expression. NG2 was detected in a fraction of the EGFP+GFAP+ cells found at 10 dpl. By 30 dpl the number of EGFP+GFAP+ cells had decreased more than four‐fold from 10 dpl. A similar transient appearance of EGFP+GFAP+ cells with simple morphology was observed in NG2creER™:ZEG double transgenic mice in which EGFP expression had been induced in NG2 cells prior to injury. NG2 cell‐specific deletion of the oligodendrocyte lineage transcription factor Olig2 using NG2creER™:Olig2fl/fl:ZEG triple transgenic mice did not increase the number of EGFP+ reactive astrocytes. These findings suggest that NG2 cells are not a major source of reactive astrocytes in the neocortex. © 2011 Wiley‐Liss, Inc.
Effects of aging on 5‐HT2AR binding: a HRRT PET study with and without partial volume corrections
Authors: Uchida Hiroyuki , Chow Tiffany W. , Mamo David C. , Kapur Shitij , Mulsant Benoit H. , Houle Sylvain , Pollock Bruce G. , Graff‐Guerrero Ariel 
Published: February 2011

AbstractObjectiveWe explored whether prior findings of reduction in serotonin 2A receptor (5‐HT2AR) binding with age could be replicated and whether high resolution research tomography (HRRT) for positron emission tomography could compensate for partial volume effects in the presence of age‐related brain atrophy, which has been a traditional concern for radioligand PET studies in the elderly.MethodsWe derived 5‐HT2AR nondisplaceable binding potentials (BPND) in frontal, temporal, anterior‐cingulate, insula, caudate and putamen volumes of interest (VOIs) for 28 healthy subjects (mean ± SD age = 43.9 ± 17.0 years, range: 19–78 years) using HRRT. Partial volume correction (PVC) was performed in the VOI analysis.ResultsThe 5‐HT2AR BPNDs decreased with age, a relationship best described by an exponential‐decay regression. The BPNDs were found to be consistent before and after PVC, with an intra‐class correlation coefficient of 0.84 and 95% confidence interval = 0.78–0.88.ConclusionsThese new findings update current knowledge, in that the aging process is not always uniform across the life span and suggest that PVC may not be necessary with HRRT in healthy subjects. Copyright © 2011 John Wiley & Sons, Ltd.
Depressive symptoms predict longitudinal change in executive control but not memory
Authors: Royall Donald R. , Palmer Raymond , Chiodo Laura K. , Polk Marsha J. 
Published: February 2011

AbstractObjectiveDepression in non‐demented persons has been identified as a possible risk factor for incident Alzheimer's disease (AD).MethodsLatent Growth Curve models were developed of baseline depressive symptoms as a predictor of longitudinal changes in cognition. Depressive symptoms were assessed using the 15‐item Geriatric Depression Scale (GDS). Memory was assessed by the California Verbal Learning Task (CVLT). Executive control function (ECF) was assessed by the Executive Interview (EXIT25) and Trail‐Making Test Part B (Trails‐B). Five hundred forty‐seven non‐institutionalized older retirees living in a single comprehensive care retirement community participated.ResultsDepressive symptoms were significantly associated only with the 3‐year rate of decline in psychomotor speed, as measured by Trails A, and ECF, as measured by the EXIT25. Both associations withstood adjustment for age, gender, education, and baseline level of care.ConclusionsDepressive symptoms are associated with longitudinal decline in cognition. However, this association selectively involves executive control, not memory, and possibly only a subset of ‘executive’ functions. Although depressive symptoms may hasten conversion from mild cognitive impairment (MCI) to dementia, depression‐related conversion is not likely to be mediated by evolution of the AD pathological process. Copyright © 2011 John Wiley & Sons, Ltd.
Overweight and obesity and the utilization of primary care physicians
Authors: Gupta Nabanita Datta , Greve Jane 
Published: February 2011

AbstractWe investigate whether overweight or obese individuals utilize more medical care than normal weight individuals by estimating a finite mixture model which splits the population into frequent and non‐frequent users of primary care physician (GP) services. Based on a survey sample aged 25–60 years from the National Health Interview (NHI) 2000 merged to Danish register data, we compare differences in the impact of being overweight and obese relative to being normal weight on the utilization of GP services. Estimated bodyweight effects vary across latent classes and show that being obese or overweight does not increase the utilization of GP services among infrequent users but does so among frequent users. Obese (and to a lesser extent, overweight) infrequent users are observed 5 years later to substantially increase their health‐care usage as measured by doctor visits, hospitalizations, and number of bed days. Copyright © 2011 John Wiley & Sons, Ltd.