bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tetrahedrane—Dossier of an Unknown
Authors: Nemirowski Adelina , Reisenauer Hans Peter , Schreiner Peter R. 
Published: August 2006

AbstractTo probe whether tetrahedrane should be isolable the thermodynamics and kinetics of C4H4 singlet and triplet structures were studied extensively at the CCSD(T)/cc‐pVTZ//CCSD(T)/cc‐pVDZ, CCSD(T)/cc‐pVDZ, CCSD(T)/cc‐pVDZ//B3 LYP/6–311G**, and B3 LYP/6–311G** levels of theory. The reaction of cyclopropene with atomic carbon, which was previously suggested to involve tetrahedrane as a reactive intermediate, was re‐examined experimentally with low‐temperature matrix‐isolation techniques. While experimental and theoretical results exclude the intermediacy of tetrahedrane in the above reaction, it is predicted to be an isolable molecule. Among the many C4H4 species, we pay special attention to the electronic effects on the ground state multiplicity of the respective carbenes.
Modified Pyridine‐Bis(imine) Iron and Cobalt Complexes: Synthesis, Structure, and Ethylene Polymerization Study
Authors: Pelascini Frédéric , Wesolek Marcel , Peruch Frédéric , Lutz Pierre J. 
Published: August 2006

AbstractIn this paper, we describe the synthesis of two new pyridine‐bis(imine)s {4‐chloro‐2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl]pyridine and 2,6‐bis[1‐(2,6‐dimethylcyclohexylimino)ethyl]pyridine} and their complexation with iron and cobalt dichloride. The solid‐state structure of the iron complexes was solved and found to be very close to catalysts already described by Brookhart and Gibson. Their ability to polymerize ethylene was investigated after activation with MAO. It was thus shown that the substitution of the pyridine ring of the ligand is unfavorable: their catalytic activity is rather low. The replacement of the aromatic rings on the imine functions by dimethylcyclohexyl rings resulted in a complete loss of activity of the iron complex for oligomerization and polymerization of ethylene. With the cobalt analog, polymerization of ethylene could be achieved under the same conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis, Structures, and Luminescent Properties of d10 Group 12 Metal Complexes with Substituted 2,2′‐Bipyridine Ligands
Authors: Liu Xiao‐ming , Mu Xiao‐yue , Xia Hong , Ye Ling , Gao Wei , Wang Hao‐yu , Mu Ying 
Published: August 2006

AbstractFour d10 group 12 metal complexes, 6‐(2‐methoxyphenyl)‐2,2′‐bipyridinezinc dichloride (2a), ‐mercury dichloride (2b), 6‐[2‐(dimethylamino)phenyl]‐2,2′‐bipyridinezinc dichloride (2c), and ‐mercury dichloride (2d), were synthesized and the structures determined by single‐crystal X‐ray crystallography. Complexes 2a and 2b are four‐coordinate and adopt a distorted tetrahedral geometry, while complexes 2c and 2d are five‐coordinate with a distorted trigonal bipyramidal geometry for the metal center. Luminescent properties of complexes 2a–2d in both solution and the solid state were studied. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Site‐Specific Recognition of Dipeptides Through Non‐Covalent Inter‐Ligand Interactions for the Hydrolysis of Dipeptide to Amino Acid Ligands Mediated by Ternary Cobalt(III) Complexes
Authors: Jitsukawa Koichiro , Mabuchi Tomohiro , Einaga Hisahiko , Masuda Hideki 
Published: August 2006

AbstractMolecular recognition of dipeptide (DP) compounds is performed with a ternary cobalt(III) complex containing thetripodal tetradentate ligand bis‐N,N‐carboxymethyl‐L‐phenylalanine (H3bcmpa). The coordination structure of the complex [Co(bcmpa)(dp)]– (1–14) was spectroscopically assigned by UV/Vis, CD, and 1H NMR spectroscopic methods. Site‐specific recognition of the dipeptide on the ternary complex is achieved by various weak, non‐covalent, inter‐ligand interactions, such as hydrogen bonding, steric repulsion, and electrostatic interaction, etc. Some dipeptides having C‐terminal aromatic side‐chains also demonstrate inter‐ligand CH–π interactions between the aromatic ring and the α‐hydrogen of bcmpa. Coordination of the N‐terminal nitrogen atom of the dipeptide to cobalt at the trans(N)‐position to the tertiary nitrogen of bcmpa in the octahedral geometry provides an aminopeptidase model. Under slightly alkaline conditions, the dipeptide ligand of some of these complexes is cleaved to give the ternary complex, [Co(bcmpa)(aa)]– (aa = amino acidato). The rate for the hydrolysis of dipeptide decreases upon increasing the steric bulkiness of the C‐terminal side‐chain. In the cases of the ternary complexes [Co(bcmpa)(gly‐phe)]– (6 and 11), which have C‐terminal L‐ or D‐phenylalanine, the hydrolysis of gly‐phe to gly was completely prevented. On the other hand, the ternary cobalt(III) complexes [Co(bcmga)(gly‐phe)]– (18 and 19), where H3bcmga (bis‐N,N‐carboxymethyl‐L‐glutamic acid) is the more hydrophilic tripodal ligand, give a small amount of the corresponding cleavage product [Co(bcmga)(gly)]–. The hydrophobic sphere generated around the metal complex in 6 and 11 regulates approach of OH– ion to the amide carbonyl group. Multi‐site interactions mediated on the ternary complexes are available for the design of an artificial hydrolysis enzyme. This is the first report describing the substrate‐specific cleavage of peptides using a simple enzyme model complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Substituted Cyclobutenes, Their Preparation, and Their Versatility in Synthesis
Authors: Gauvry Noëlle , Lescop Cyrille , Huet François 
Published: August 2006

AbstractCyclobutene compounds are interesting intermediates that have proven to be useful in organic synthesis. This review mainly deals with preparations and reactions of some cyclobutenes disubstituted at the allylic position. Several possibilities in the area of the thermal ring opening of these compounds into dienes are explored, and some features of the selectivity of addition reactions to cyclobutenes to afford tri‐ or tetrasubstituted cyclobutanes are also examined. When suitable leaving groups are present, these cyclobutanes can yield cyclopropanes stereospecifically through ring contraction or bicyclic compounds through intramolecular cyclization. Some applications to the synthesis of nucleoside analogues and of bicyclic compounds are pointed out. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Intramolecular Nonbonding Interactions between Selenium and Sulfur – Spectroscopic Evidence and Importance in Asymmetric Synthesis
Authors: Tiecco Marcello , Testaferri Lorenzo , Santi Claudio , Tomassini Cristina , Santoro Stefano , Marini Francesca , Bagnoli Luana , Temperini Andrea , Costantino Ferdinando 
Published: August 2006

AbstractChiral sulfur‐containing electrophilic selenium reagents can be employed to effect efficient asymmetric syntheses. Spectroscopic and chemical evidence demonstrate that the observed high selectivity of the asymmetric reactions is associated with a nonbonding selenium–sulfur interaction that is present in both the crystalline form and in solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Liquid Crystals Based on Axially Fluorinated 1,3‐Dioxanes: Synthesis, Properties and Computational Study
Authors: Kirsch Peer , Hahn Alexander , Fröhlich Roland , Haufe Günter 
Published: August 2006

AbstractA new class of liquid crystals with strongly negative dielectric anisotropy has been prepared by the exploitation of the somewhat “ambivalent” characteristics of the 1,3‐dioxane structure with respect to its polarity and by the axial fluorination of this structure, which gives these compounds attractive mesogenic and electrooptic properties. The increased chemical stability of these materials compared with their carbocyclic analogues has been analyzed and explained by molecular modelling. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
How much of a good thing is too much? Explaining the failure of a well‐designed, well‐executed intervention in Juvenile Hall for “hard‐to‐place” delinquents
Authors: Parker Robert Nash , Asencio Emily K. , Plechner Deborah 
Published: August 2006

AbstractThis chapter focuses on lessons concerning the design of interventions and the interpretation of outcome and cost‐benefit analyses. An intervention can “fail” due to the implementation of an intervention component in the context of standard treatments, and the interpretation of costs and benefits can change substantially if one considers the alternative long‐term outcomes in the absence of the intervention.
What works (and what does not) in youth violence prevention: Rethinking the questions and finding new answers
Authors: Guerra Nancy G. , Boxer Paul , Cook Clayton R. 
Published: August 2006

AbstractOver the past decades, public concern over youth violence has led to a proliferation of prevention programs as well as a corresponding push to identify programs that “work.” A more accurate understanding of effectiveness as well as failure can be found by reframing the questions to ask what works, for whom, and under what conditions.
Who is watching the watchers? The challenge of observing peer interactions on elementary school playgrounds
Authors: Hudley Cynthia 
Published: August 2006

AbstractThis chapter discusses a multisite program evaluation in elementary schools that incorporated playground observations to document student behavior. A number of challenges are discussed, some of which were consistent with observer reactivity effects long documented in the literature, while others we believe were unique to this particular setting and provide a cautionary tale for those collecting school‐based observation data.
Spatial relationship of source localizations in patients with focal epilepsy: Comparison of MEG and EEG with a three spherical shells and a boundary element volume conductor model
Authors: Scheler Gabriela , Fischer Michael J.M. , Genow Alexandra , Hummel Cornelia , Rampp Stefan , Paulini Andrea , Hopfengärtner Rüdiger , Kaltenhäuser Martin , Stefan Hermann 
Published: August 2006

AbstractEpilepsy surgery is an option for patients with pharmacoresistant focal epilepsies, but it requires a precise focus localization procedure. Magnetoencephalography (MEG) and electroencephalography (EEG) can be used for analysis of interictal activity. The aim of this prospective study was to compare clusters of source localization results with MEG and EEG using a three spherical shells (3SS) and a boundary element method (BEM) volume conductor model. The study was closed when 100 patients met the inclusion criteria. Simultaneous MEG and EEG were recorded during presurgical evaluation. Epileptiform signals were analyzed using an equivalent current dipole model. Centroids of source localizations from MEG, EEG, 3SS, and BEM in their respective combinations were compared. In a 3SS model, MEG source localizations were 5.6 mm inferior to those obtained by EEG, while in a BEM model MEG source localizations were 6.3 mm anterior and 4.8 mm superior. The mean scattering of source localizations between both volume conductor models was 19.5 mm for EEG and 9.6 mm for MEG. For MEG no systematic difference between BEM and 3SS source localizations was found. For EEG, source localizations with BEM were 5.9 mm posterior and 11.7 mm inferior to those determined using 3SS. No differences were found between the 46 temporal and the 54 extratemporal lobe epilepsy patients. The observed systematic differences of source localizations of epileptic spikes due to the applied source signal modality and volume conductor model should be considered in presurgical evaluation when only one source signal and volume conductor model is available. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Nonlinear local electrovascular coupling. II: From data to neuronal masses
Authors: Riera J.J. , Jimenez J.C. , Wan X. , Kawashima R. , Ozaki T. 
Published: August 2006

AbstractIn the companion article a local electrovascular coupling (LEVC) model was proposed to explain the continuous dynamics of electrical and vascular states within a cortical unit. These states produce certain mesoscopic reflections whose discrete time series can be reconstructed from electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). In this article we develop a recursive optimization algorithm based on the local linearization (LL) filter and an innovation method to make statistical inferences about the LEVC model from both EEG and fMRI data, i.e., to estimate the unobserved states and the unknown parameters of the model. For a better understanding, the LL filter is described from a Bayesian point of view, providing the particulars for the case of hybrid data (e.g., EEG and fMRI), which could be sampled at different rates. The dynamics of the exogenous synaptic inputs going into the cortical unit are also estimated by introducing a set of Gaussian radial basis functions. In order to study the dynamics of the electrical and vascular states in the striate cortex of humans as well as their local interrelationships, we applied this algorithm to EEG and fMRI recordings obtained concurrently from two subjects while passively observing a radial checkerboard with a white/black pattern reversal. The EEG and fMRI data from the first subject was used to estimate the electrical/vascular states and parameters of the LEVC model in V1 for a 4.0 Hz reversion frequency. We used the EEG data from the second subject to investigate the changes in the dynamics of the electrical states when the frequency of reversion is varied from 0.5–4.0 Hz. Then we made use of the estimated electrical states to predict the effects on the vasculature that such variations produce. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
fMRI changes in relapsing‐remitting multiple sclerosis patients complaining of fatigue after IFNβ‐1a injection
Authors: Rocca Maria A. , Agosta Federica , Colombo Bruno , Mezzapesa Domenico M. , Falini Andrea , Comi Giancarlo , Filippi Massimo 
Published: August 2006

AbstractIf fatigue in multiple sclerosis (MS) is related to an abnormal activation of the sensorimotor brain network, the activity of such a network should vary with varying fatigue. We studied 22 patients treated with interferon beta 1a (IFNβ‐1a; Avonex, Biogen, Cambridge, MA) with no fatigue (10) and with reversible fatigue (12). fMRI examinations were performed: 1) the same day of IFNβ‐1a injection (no fatigue; entry), 2) the day after IFNβ‐1a injection (fatigue; time 1), and 3) 4 days after IFNβ‐1a injection (no fatigue; time 2). Patients performed a simple motor task with the right, clinically unaffected hand. At time 1, compared with entry and time 2, MS patients with reversible fatigue showed an increased activation of the thalamus bilaterally. In MS patients without fatigue thalamus was more activated at entry than at time 1. In both groups at entry the primary SMC and the SMA were more activated than at times 1 and 2. At entry and time 1, when compared to patients with reversible fatigue, those without showed increased activations of the SII. Conversely, patients with reversible fatigue had increased activations of the thalamus and of several regions of the frontal lobes. An abnormal recruitment of the fronto‐thalamic circuitry is associated with IFNβ‐1a‐induced fatigue in MS patients. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Epstein‐Barr virus (EBV) serology for predicting distant metastases in a white juvenile patient with nasopharyngeal carcinoma and no clinical response to EBV lytic induction therapy
Authors: Stevens Servi J. C. , Zwaan Christian M. , Verkuijlen Sandra A. W. M. , Middeldorp Jaap M. 
Published: August 2006

AbstractBackground.We describe a case of a 16‐year‐old white girl with Epstein‐Barr virus (EBV)‐positive nasopharyngeal carcinoma (NPC).Methods.At diagnosis, the patient had characteristic immunoglobulin (Ig)A and IgG responses to EBNA1, viral capsid antigen (VCA)‐p18, and early antigens (EAs), with no detectable EBV DNA in her blood. Combined chemotherapy and radiotherapy resulted in complete remission. Eighteen months later, the patient's IgA responses to EBNA1 and p18 and both IgA and IgG anti‐EA increased, without apparent recurrence. Five months later, lung metastases were found. She underwent surgical removal of the lung metastases and conventional chemotherapy, but had intraabdominal lymph node metastasis and mediastinal lesions develop. The patient was then treated with a novel treatment consisting of 5‐fluorouracil plus valproic acid and subsequent valganciclovir to induce lytic EBV replication. This resulted in the first detectable EBV DNA levels in the blood but did not result in clinical response.Results.The patient's disease progressed, and the patient declined further cancer treatment and died.Conclusion.In contrast to EBV DNA load, EBV serology was useful in predicting distant NPC metastasis after initial complete remission in this patient. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
Rare living hypopharyngeal foreign body
Authors: Kuehnemund Matthias , Bootz Friedrich 
Published: August 2006

AbstractBackground.This is a case report about a rare hypopharyngeal foreign body causing dysphagia, dyspnea, and hemoptysis as well as melena: an ingested leech. The patient was in this condition for more than 1 week.Methods.The ingested leech, attached to the right piriform fossa partially obstructing the larynx, had to be removed under general anesthesia.Results.After removal, no further symptoms occurred. The leech was identified as the species Theromyzon tessulatum.Conclusions.Human infestation of a leech in the upper aerodigestive tract is a very rare condition in urban areas. The current literature is reviewed and the diagnostic approach as well as therapeutic options are discussed. © 2006 Wiley Periodicals, Inc. Head Neck, 2006
Thoracic duct cyst: Sclerotherapy as alternative for surgical treatment
Authors: Dool Johannes J. , de Bree Remco , van den Berg René , Leemans C. René 
Published: August 2006

AbstractBackground.Thoracic duct cysts of the cervical portion are rare benign lesions for which surgery is the treatment of choice.Methods.We present 2 cases of a thoracic duct cyst of the cervical portion. One patient was treated by surgery and the other patient by ethanol sclerotherapy.Results.After establishing diagnosis by radiologic assessment and chemical and cytological fine‐needle aspirate of the cystic masses, both patients were treated successfully.Conclusion.Ethanol sclerotherapy provides an alternative therapy for thoracic duct cyst when evaluation establishes a high likelihood of clinical diagnosis. © 2006 Wiley Periodicals, Inc. Head Neck, 2007
Inducible nitric oxide synthase up‐regulation and mitochondrial glutathione depletion mediate cyanide‐induced necrosis in mesencephalic cells
Authors: Prabhakaran K. , Li L. , Borowitz J.L. , Isom G.E. 
Published: August 2006

AbstractWe have previously shown in rat primary cultured mesencephalic cells that cyanide induces a high level of oxidative stress and necrotic death. To evaluate the mechanism of the cytotoxicity, the effects of cyanide on intracellular glutathione (GSH) pools and inducible nitric oxide synthase (iNOS)‐mediated reactive nitrogen species (RNS) generation were studied. Cyanide rapidly depleted intracellular GSH. Restoration of GSH blocked cell death, whereas depletion of GSH by synthesis inhibition increased the necrosis. Selective depletion of mitochondrial GSH (mtGSH) increased oxidative stress and enhanced cell death, whereas the cytoplasmic pool was not critical to cell survival. These actions were accompanied by increased iNOS expression as determined by Western blot analysis, RT‐PCR and immunohistochemistry. Up‐regulation of iNOS led to increased generation of NO as reflected by elevated nitrite levels (an end product of NO metabolism). It was determined by use of a selective inhibitor that up‐regulation of iNOS expression was transcriptionally regulated by activation of nuclear factor‐κB, a redox‐sensitive transcription factor. It was concluded that, in cyanide‐mediated neurotoxicity, mtGSH is a vital component of the cellular antioxidant defense, and its depletion can lead to oxidative stress‐mediated iNOS up‐regulation, thus enhancing RNS generation and necrosis. © 2006 Wiley‐Liss, Inc.
Aspiration during swallowing in typically developing children of the first nations and inuit in Canada
Authors: Rempel Gina R. , Borton Barbara L. , Kumar Rajesh 
Published: August 2006

AbstractChildren of the First Nations and Inuit in Canada have a high propensity for lower respiratory tract infections. Overcrowding, poor housing, passive smoke exposure, and lack of breast feeding (Martens P, Bond R, Jebamani L, Burchill C, et al.http://www.umanitoba.ca/centres/mchp/reports/pdfs/rfn_pdfs/rfn_report.pdf.; MacMillan H, Walsh C, Jamieson E, Crawford A, Boyle M.http://www.hcsc.gc.ca/fnihbdgspni/fnihb/aboriginalhealth/reports_summaries/regional_survey_ch1.pdf.; Wardman AE, Khan NA. Int J Circumpolar Health 2004;63:81–92) have been cited as important contributing factors in the occurrence of lower respiratory tract infections. However, aspiration during swallowing has thus far not been considered as a co‐factor in the occurrence of lower respiratory tract infections in these children. We present a retrospective case series of seven typically developing children of the Canadian First Nations and Inuit, in whom aspiration during swallowing was detected in the course of investigating associations with recurrent lower respiratory tract infections. None of the children had any of the known risk factors for aspiration during swallowing such as developmental variation, prematurity, neuromotor problems, or anatomic abnormalities of the upper aerodigestive tract. We speculate that aspiration during swallowing in typically developing children may be an important, previously unrecognized co‐factor in the occurrence of lower respiratory tract infections, particularly in the communities of the Canadian First Nations and Inuit. Further prospective studies will be needed to determine whether aspiration during swallowing represents an independent risk factor for the occurrence of lower respiratory tract infections in these children. Pediatr Pulmonol. 2006, 41:912–915. © 2006 Wiley‐Liss, Inc.
PIPER: An FFT‐based protein docking program with pairwise potentials
Authors: Kozakov Dima , Brenke Ryan , Comeau Stephen R. , Vajda Sandor 
Published: August 2006

AbstractThe Fast Fourier Transform (FFT) correlation approach to protein–protein docking can evaluate the energies of billions of docked conformations on a grid if the energy is described in the form of a correlation function. Here, this restriction is removed, and the approach is efficiently used with pairwise interaction potentials that substantially improve the docking results. The basic idea is approximating the interaction matrix by its eigenvectors corresponding to the few dominant eigenvalues, resulting in an energy expression written as the sum of a few correlation functions, and solving the problem by repeated FFT calculations. In addition to describing how the method is implemented, we present a novel class of structure‐based pairwise intermolecular potentials. The DARS (Decoys As the Reference State) potentials are extracted from structures of protein–protein complexes and use large sets of docked conformations as decoys to derive atom pair distributions in the reference state. The current version of the DARS potential works well for enzyme–inhibitor complexes. With the new FFT‐based program, DARS provides much better docking results than the earlier approaches, in many cases generating 50% more near‐native docked conformations. Although the potential is far from optimal for antibody–antigen pairs, the results are still slightly better than those given by an earlier FFT method. The docking program PIPER is freely available for noncommercial applications. Proteins 2006. © 2006 Wiley‐Liss, Inc.