bluuebunny/crossref_metadata_2025 huggingface dataset:
The Pyridyldiisopropylsilyl Group: A Masked Functionality and Directing Group for Monoselective ortho‐Acyloxylation and ortho‐Halogenation Reactions of Arenes
Authors: Huang Chunhui , Chernyak Natalia , Dudnik Alexander S. , Gevorgyan Vladimir
Published: May 2011

A novel, easily removable and modifiable silicon‐tethered pyridyldiisopropylsilyl directing group for CH functionalizations of arenes has been developed. The installation of the pyridyldiisopropylsilyl group can efficiently be achieved via two complementary routes using easily available 2‐(diisopropylsilyl)pyridine (5). The first strategy features a nucleophilic hydride substitution at the silicon atom in 5 with aryllithium reagents generated in situ from the corresponding aryl bromides or iodides. The second milder route exploits a highly efficient room‐temperature rhodium(I)‐catalyzed cross‐coupling reaction between 5 and aryl iodides. The latter approach can be applied to the preparation of a wide range of pyridyldiisopropylsilyl‐substituted arenes possessing a variety of functional groups, including those incompatible with organometallic reagents. The pyridyldiisopropylsilyl directing group allows for a highly efficient, regioselective palladium(II)‐catalyzed mono‐ortho‐acyloxylation and ortho‐halogenation of various aromatic compounds. Most importantly, the silicon‐tethered directing group in both acyloxylated and halogenated products can easily be removed or efficiently converted into an array of other valuable functionalities. These transformations include protio‐, deuterio‐, halo‐, boro‐, and alkynyldesilylations, as well as a conversion of the directing group into the hydroxy functionality. In addition, the construction of aryl‐aryl bonds via the Hiyama–Denmark cross‐coupling reaction is feasible for the acetoxylated products. Moreover, the ortho‐halogenated pyridyldiisopropylsilylarenes, bearing both nucleophilic pyridyldiisopropylsilyl and electrophilic aryl halide moieties, represent synthetically attractive 1,2‐ambiphiles. A unique reactivity of these ambiphiles has been demonstrated in efficient syntheses of arylenediyne and benzosilole derivatives, as well as in a facile generation of benzyne. In addition, preliminary mechanistic studies of the acyloxylation and halogenation reactions have been performed. A trinuclear palladacycle intermediate has been isolated from a stoichiometric reaction between diisopropyl(phenyl)pyrid‐2‐ylsilane (3a) and palladium acetate. Furthermore, both CH functionalization reactions exhibited equally high values of the intramolecular primary kinetic isotope effect (kH/kD=6.7). Based on these observations, a general mechanism involving the formation of a palladacycle via a CH activation process as the rate‐determining step has been proposed.
Tandem Catalysis by Lipase in a Vinyl Acetate‐Mediated Cross‐Aldol Reaction
Authors: Kumar Manjeet , Shah Bhahwal A. , Taneja Subhash C.
Published: May 2011

The lipase Novozym435 (0.6% w/w) was used in tandem with organocatalysts in a first vinyl/isopropenyl acetate‐mediated aldol reaction. The reaction was facilitated through the lipase‐catalyzed in situ generation of acetaldehyde/acetone. The important features of the present methodology include the mild and facile reaction conditions, regenerability of the lipase, comparatively high yields and minimal side product formation.
Convenient and Selective Hydrogenation of Nitro Aromatics with a Platinum Nanocatalyst under Ambient Pressure
Authors: Xu Kunling , Zhang Yuan , Chen Xiaorong , Huang Lei , Zhang Rui , Huang Jun
Published: May 2011

A convenient and highly selective platinum nanocatalyst was developed for the hydrogenation of nitro aromatics into the corresponding anilines at room temperature under ambient pressure. The platinum catalyst was highly active and selective for the hydrogenation of nitro aromatic compounds. Reducible groups such as aldehyde, ketone and nitrile were untouched during the hydrogenation of the corresponding nitro compounds, and the corresponding anilines were obtained quantitatively.
Magnetically Recoverable Nanoparticles: Highly Efficient Catalysts for Asymmetric Transfer Hydrogenation of Aromatic Ketones in Aqueous Medium
Authors: Liu Guohua , Gu Hongyuan , Sun Yunqiang , Long Jie , Xu Yulong , Li Hexing
Published: May 2011

Two magnetic chiral iridium and rhodium catalysts were prepared via directly postgrafting 1,2‐diphenylethylenediamine‐derived organic silica or 1,2‐cyclohexanediamine‐derived organic silica onto the silica‐coated iron oxide nanoparticles followed by complexation with iridium(III) or rhodium(III) complexes. During the asymmetric transfer hydrogenation of aromatic ketones in aqueous medium, the magnetic chiral catalysts exhibited high catalytic activities (up to 99% conversion) and enantioselectivities (up to 92% ee). Both catalysts could be recovered easily by magnetic separation and be reused ten times without significantly affecting their catalytic activities and enantioselectivities.
Mechanistic Switch via Subtle Ligand Modulation: Palladium‐Catalyzed Synthesis of α,β‐Substituted Styrenes via CH Bond Functionalization
Authors: Flores‐Gaspar Areli , Martin Ruben
Published: May 2011

A new catalyst system able to efficiently perform the synthesis of styrenes via CH bond functionalization and a subtle ligand modification are described. The high level of activity achieved allows for the synthesis of highly functionalized α,β‐substituted styrenes, even the elusive E‐configured trisubstituted olefins, in a regio‐ and stereoselective manner. Mechanistic experiments allowed for the identification of the corresponding synthetic intermediates.
Grignard‐Type Arylation of Aldehydes via a Rhodium‐Catalyzed CH Activation under Mild Conditions
Authors: Yang Luo , Correia Camille A. , Li Chao‐Jun
Published: May 2011

An efficient Grignard‐type arylation of aldehydes via aryl CH activation was achieved under mild conditions catalyzed by rhodium. The reaction provides an easy access to a wide variety of benzyl alcohols and can tolerate various functional groups as well as air and water.
IRon overload screeNing tool (IRON): Development of a tool to guide screening in primary care
Authors: Mainous Arch G. , Diaz Vanessa A. , Everett Charles J. , Knoll Michele E. , Hulihan Mary M. , Grant Althea M. , McLaren Christine E. , McLaren Gordon D.
Published: May 2011

Iron overload is associated with significant morbidity and mortality yet is easily treated. The objective of this study was to create a tool that could be easily adapted to clinical practice that indicates the likelihood of a patient having undetected iron overload. We used the National Health and Nutrition Examination Survey (NHANES) 1999–2002 for US adults aged 20 years and older to build a model (unweighted n=8,779). We chose potential variables for inclusion that could be gathered by self‐report or measured without laboratory data and were suggested by past literature on hemochromatosis and iron overload. We computed logistic regressions to create the scores by initially evaluating the variables' relationship with elevated ferritin and elevated transferrin saturation and then using odds ratios to correspond to scores. The resulting score on the IRon Overload ScreeNing Tool (IRON) was then validated with data on 13,844 adults in the NHANES III, 1988–94. Predictors in the final tool were age, gender, previous diagnoses of liver condition, osteoporosis or thyroid disease. The IRON score yielded an area under the curve (AUC) in the NHANES 1999–02 of 0.720 and an AUC of 0.685 in the NHANES III validation sample. The IRON score is a tool to assist in identification of patients with iron overload that has several qualities that make it attractive for use in clinical practice with an undifferentiated patient population including brevity, easily collected information and predictive ability comparable to other tools that help in directing screening. Am. J. Hematol. 2011. © 2011 Wiley‐Liss, Inc.
Carious lesions and maize consumption among the Prehispanic Maya: An analysis of a coastal community in northern Yucatan
Authors: Cucina Andrea , Cantillo Cristina Perera , Sosa Thelma Sierra , Tiesler Vera
Published: May 2011

Patterns of carious lesions were analyzed in the Classic period coastal Maya population of Xcambó, a salt production and administration center in northern Yucatan. To this end, the study investigated caries in the permanent dentitions of 163 adult skeletons, 23 from the Early Classic (AD 250–550) and 140 from the Late Classic period (AD 550–750), equally distributed between sexes. The archaeological and bioarchaeological evidence indicates a wealthy and socially homogeneous population dedicated to salt production and administration in the Early Classic that switched to pure administrative functions in the Late Classic. The results indicate an increase in caries from 7.4% and 21.2% (males and females respectively) from the Early Classic to 14.0% in males and 27.4% in females from the Late Classic period. The rate of caries in the Early and in the Late Classic phases of continuous occupation is not consistent with a simple interpretation of a heavier reliance on maize during the latter phase, characterized by a sedentary lifestyle, particularly for the male segment of the society now dedicated completely to the administration of the salt mines. Rather, the increase in caries rates in both sexes is best explained within a broader context of overall food habits, new cariogenic foods for both sexes, and the changes in lifestyle imposed by the increased socioeconomic role of the site. Our conclusions stress the limitations imposed by interpreting carious lesions solely in terms of single dietary components, such as maize consumption, without taking into account broader aspects of cultural and socioeconomic relevance. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Tooth evolution and dental defects: From genetic regulation network to micro‐RNA fine‐tuning
Authors: Michon Frederic
Published: May 2011

Teeth, like all epithelial appendages, form via a sequential and reciprocal series of inductive signals between the epithelium and the underlying mesenchyme. The genes involved in this signaling network regulating ectodermal organ development have been highly conserved during evolution and are gaining more understanding in great detail. The specific functions of numerous genes during embryogenesis are known, and the involvement of their mutations in the pathogenesis of congenital defects is being extensively studied. Recently, the micro‐RNA (miRNA) pathway has been associated with various aspects of embryogenesis including ectodermal organ formation and odontogenesis. In this review, I presented the genetic network involved during tooth formation and evolution, and several mutations that give rise to dental defects. The possible impact of fine‐tuning and network regulation by miRNAs on development, evolution of teeth, and defects are, therefore, discussed. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.
Tbx1, subpulmonary myocardium and conotruncal congenital heart defects
Authors: Parisot Pauline , Mesbah Karim , Théveniau–Ruissy Magali , Kelly Robert G.
Published: May 2011

Conotruncal congenital heart defects, including defects in septation and alignment of the ventricular outlets, account for approximately a third of all congenital heart defects. Failure of the left ventricle to obtain an independent outlet results in incomplete separation of systemic and pulmonary circulation at birth. The embryonic outflow tract, a transient cylinder of myocardium connecting the embryonic ventricles to the aortic sac, plays a critical role in this process during normal development. The outflow tract (OFT) is derived from a population of cardiac progenitor cells called the second heart field that contributes to the arterial pole of the heart tube during cardiac looping. During septation, the OFT is remodeled to form the base of the ascending aorta and pulmonary trunk. Tbx1, the major candidate gene for DiGeorge syndrome, is a critical transcriptional regulator of second heart field development. DiGeorge syndrome patients are haploinsufficient for Tbx1 and present a spectrum of conotruncal anomalies including tetralogy of Fallot, pulmonary atresia, and common arterial trunk. In this review, we focus on the role of Tbx1 in the regulation of second heart field deployment and, in particular, in the development of a specific population of myocardial cells at the base of the pulmonary trunk. Recent data characterizing additional properties and regulators of development of this region of the heart, including the retinoic acid, hedgehog, and semaphorin signaling pathways, are discussed. These findings identify future subpulmonary myocardium as the clinically relevant component of the second heart field and provide new mechanistic insight into a spectrum of common conotruncal congenital heart defects. Birth Defects Research (Part A), 2011. © 2011 Wiley‐Liss, Inc.
Structural evidence for stabilization of inhibitor binding by a protein cavity in the dehaloperoxidase‐hemoglobin from Amphitrite ornata
Authors: de Serrano Vesna , Franzen Stefan
Published: May 2011

A functional role for a protein cavity that stabilizes inhibitor binding has been established based on a comparison of Xe‐derivatized and inhibitor‐bound X‐ray crystal structures in dehaloperoxidase‐hemoglobin (DHP A) of Amphitrite ornata. The internal binding affinity of four different inhibitors, 4‐fluorophenol, 4‐chlorophenol, 4‐bromophenol, and 4‐iodophenol in the distal pocket has been shown previously to increase proportional to the radius of the para‐halogen atom. Inhibition of oxidation of the native substrate, 2,4,6‐tribromophenol, has been shown to follow the trend in inhibitor binding strength, because of a two‐site competitive inhibition mechanism that involves displacement of the substrate by the inhibitor in a gated mechanism involving the distal histidine of DHP A. In this study, it is shown that the origin of the stronger binding by a larger para‐halogen substituent coincides structurally with a Xe‐binding cavity (Xe1) characterized structurally by X‐ray crystallography. The Xe1 site is surrounded by amino acid resides L100, F21, F24, F35, F60, and V59 in the distal pocket, located 4.8 Å from the heme iron, in a position that is coincident with the para‐bromine atom of the inhibitor 4‐bromophenol. 4‐bromophenol is prevalent in benthic ecosystems where A. ornata resides. A second, less well‐defined, binding site in DHP A, labeled as Xe2, is located near the surface of the protein in the vicinity of amino acid residues L62, R69, D79, T82, and L83, which may be related to substrate docking on the surface of DHP A. © 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 98: 27–35, 2012.
Oligo(N‐alkoxy glycines): Trans substantiating peptoid conformations
Authors: Jordan Peter A. , Paul Bishwajit , Butterfoss Glenn L. , Renfrew P. Douglas , Bonneau Richard , Kirshenbaum Kent
Published: May 2011

Peptoid oligomers possess many desirable attributes as bioactive peptidomimetic agents, including their ease of synthesis, chemical diversity, and capability for molecular recognition. Ongoing efforts to develop functional peptoids will necessitate improved capability for control of peptoid structure, particularly of the backbone amide conformation. We introduce alkoxyamines as a new reagent for solid phase peptoid synthesis. Herein, we describe the synthesis of N‐alkoxy peptoids, and present NMR data indicating that the oligomers adopt a single stable conformation featuring trans amide bonds. These findings, combined with results from computational modeling, suggest that N‐alkoxy peptoid oligomers have a strong propensity to adopt a polyproline II type secondary structure. © 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 617–626, 2011.
Search for identical octapeptides in unrelated proteins: Structural plasticity revisited
Authors: M. Saravanan K. , Selvaraj S.
Published: May 2011

Since proteins are dynamic in nature, they can alter their local structure in response to changes in their environment factors such as temperature, pH, phosphorylation, and binding of other small molecules. These conformational changes are extremely important for the correct folding and functioning of proteins. There are also a number of diseases associated with protein conformational change such as amyloid diseases. To stimulate research into the above factors which specify one conformation over another, different theoretical models have been proposed and tested against sequence similar distant structure protein fragments. In order to simplify the computational complexity of identifying conformational changes in proteins, various local sequence search algorithms were employed and the structural plasticity in unrelated proteins was examined by various research groups. In the present work, we revisit the mechanism of structural plasticity in unrelated proteins with increased number of structures in Protein Data Bank by comparing identical octapeptides in unrelated proteins with dictionary of protein secondary structure extracted from existing experimental data. Our goal is to bring out the influence of hydrophobic residues, hydrophilic residues, flanking residues, difference in secondary structural propensities of surrounding residues, difference in phi‐psi angles and local and nonlocal interactions in identical octapeptides adopting different conformations. Also we have used surrounding hydrophobicity, environment dependent interaction energy, atomic mean force potential, structural unit contacts and difference profiles models to explore the factors which cause structural plasticity. The results discussed here may provide insights into protein folding, design and function. © 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 98: 11–26, 2012.
Cholecystectomy as a risk factor for oesophageal adenocarcinoma
Authors: Lagergren J , Mattsson F
Published: May 2011

Background

Owing to an increased risk of oesophageal bile exposure after cholecystectomy, an association with oesophageal adenocarcinoma is possible. There are some data in support of this hypothesis, and the aim of this study was to ascertain whether the association could be confirmed.

Methods

A population-based cohort study was undertaken to compare the number of cases of oesophageal adenocarcinoma observed in a cohort of patients who have had a cholecystectomy in Sweden during 1965–2008 with the expected number, calculated from the entire Swedish population of corresponding age, sex and year. The risk of oesophageal adenocarcinoma was assessed by calculating the standardized incidence ratio (SIR) with 95 per cent confidence intervals.

Results

The cholecystectomy cohort included 345 251 patients who were followed up for a mean of 15 years and contributed 4 854 969 person-years at risk. The total of 126 new cases of oesophageal adenocarcinoma was greater than expected (SIR 1·29, 1·07 to 1·53). The strength of the association between cholecystectomy and oesophageal adenocarcinoma tended to increase with longer follow-up after cholecystectomy. There was no association between cholecystectomy and oesophageal squamous cell carcinoma (SIR 0·93, 0·81 to 1·08), and in an unoperated cohort of 192 960 patients with gallstones no increased risk of oesophageal adenocarcinoma was identified (SIR 0·99, 0·71 to 1·35).

Conclusion

Cholecystectomy appears to be linked to an increased risk of oesophageal adenocarcinoma, but the absolute risk is small.
Dietary red palm oil protects the heart against the cytotoxic effects of anthracycline
Authors: Wergeland A. , Bester D. J. , Sishi B. J. N. , Engelbrecht A. M. , Jonassen A. K. , Van Rooyen J.
Published: May 2011

Strong anti‐neoplastic anthracyclines like daunorubicin (DNR) and doxorubicin (DOX) have high efficacy against systemic neoplasm and solid tumours. However, clinically, they cause chronic cardiomyopathy and congestive heart failure. Red palm oil (RPO) supplementation can protect the heart against ischemic injury. We therefore hypothesize that supplementation with RPO during chemotherapy may protect the heart.

Control rats received a standard diet, and the experimental group received RPO in addition for 4 weeks. Each group was subsequently injected with either saline or DNR over a 12‐day period towards the end of 4 weeks. Hearts were excised and perfused on a working heart system. Functional parameters were measured. Tissue samples were collected for analysis of mRNA and protein levels. DNR + RPO increased aortic output by 25% (p < 0·05) compared with DNR only. Furthermore, DNR treatment significantly reduced tissue mRNA levels of superoxide dismutase 1 (SOD1) and nitric oxide synthase 1 (NOS1) compared with untreated controls. Protein expression of SOD1 followed the same pattern as mRNA levels. NOS1 protein levels were significantly increased in DNR treated rats when compared with untreated controls. In addition, DNR increased phosphorylation of p38 and Jun N‐terminal kinase compared with untreated controls, whereas DNR + RPO completely counteracted this activation. DNR + RPO significantly up regulated the protein extracellular signal‐regulated kinase 1 level compared with DNR only.

In this model of DNR treatment, RPO is associated with stabilization of important antioxidant enzymes such NOS and SOD, and inhibition of the ‘stress’ induced mitogen‐activated protein kinase pathways. Dietary RPO also maintained function, similar to control, in DNR treated hearts. Copyright © 2011 John Wiley & Sons, Ltd.
Functional roles of superoxide and hydrogen peroxide generated by mitochondrial DNA mutation in regulating tumorigenicity of HepG2 cells
Authors: Gao Wen , Xu Kehua , Li Ping , Tang Bo
Published: May 2011

Mitochondria are a major source of reactive oxygen species (ROS). Recent studies have estimated that mitochondrial DNA mutations inducing the overproduction of ROS are associated with human cancer. However, a substantial challenge in elucidating their diverse roles in regulating tumorigenesis is the lack of methods for probing ROS in living systems with molecular specificity. In this study, we reported the application of two fluorescent probes, 2‐chloro‐1,3‐dibenzothiazolinecyclohexene and naphthofluorescein disulfonate, which showed high selectivity for superoxide (O2•−) and hydrogen peroxide (H2O2). They were capable of detecting and visualizing O2•− and H2O2 overproduction caused by a mutation in the gene encoding nicotinamide adenine dinucleotide dehydrogenase subunit 6 (ND6) in HepG2 cells. The levels of O2•− and H2O2 in mitochondria isolated from HepG2 cells were found to be 0·63 ± 0·07  and 1·13 ± 0·05 μM, respectively. Using assays of tumorigenesis in mouse models, we found that treatment of the mice with different ROS scavengers suppressed tumour growth. These findings suggested that ROS generated by ND6 gene mutation do play an important role in regulating tumorigenesis and H2O2 may be a key modulator. Copyright © 2011 John Wiley & Sons, Ltd.
Quantum‐Sized Gold Nanoclusters: Bridging the Gap between Organometallics and Nanocrystals
Authors: Jin Rongchao , Zhu Yan , Qian Huifeng
Published: May 2011

This Concept article provides an elementary discussion of a special class of large‐sized gold compounds, so‐called Au nanoclusters, which lies in between traditional organogold compounds (e.g., few‐atom complexes, <1 nm) and face‐centered cubic (fcc) crystalline Au nanoparticles (typically >2 nm). The discussion is focused on the relationship between them, including the evolution from the Au⋅⋅⋅Au aurophilic interaction in AuI complexes to the direct AuAu bond in clusters, and the structural transformation from the fcc structure in nanocrystals to non‐fcc structures in nanoclusters. Thiolate‐protected Aun(SR)m nanoclusters are used as a paradigm system. Research on such nanoclusters has achieved considerable advances in recent years and is expected to flourish in the near future, which will bring about exciting progress in both fundamental scientific research and technological applications of nanoclusters of gold and other metals.
The Stepwise Diels–Alder Reaction of 4‐Nitrobenzodifuroxan with Danishefsky’s Diene
Authors: Steglenko Dmitry V. , Kletsky Mikhail E. , Kurbatov Sergey V. , Tatarov Artem V. , Minkin Vladimir I. , Goumont Regis , Terrier François
Published: May 2011

The Diels–Alder reaction of 4‐nitrobenzodifuroxan (NBDF) with 1‐methoxy‐3‐trimethylsilyloxy‐1,3‐butadiene has been investigated experimentally and theoretically. Treatment of NBDF with excess diene in chloroform at room temperature was found to afford a single product that contained a carbonyl functionality. Based on an X‐ray structure and NMR spectroscopic data, the product appeared to be a result of the hydrolysis of the OSiMe3 moiety of the thermodynamically more stable endo [2+4] cycloadduct, characterized by a cis arrangement of the MeO and NO2 functionalities. In situ NMR investigations of the interaction were carried out at room temperature in CDCl3 and at −40 °C in deuterated acetonitrile. Calculations at the B3LYP/6‐31G* level in the gas phase and in acetonitrile were carried out under the assumption that the most stable cis conformation of the diene is also the most reactive in the interaction. The analysis revealed the NBDF/cis diene interaction involves the formation of a zwitterionic intermediate. Importantly, this intermediate is formed in two preferred conformations, which correspond to the endo and exo modes of approach of the reagents. Cyclization of these two identified conformations afforded the experimentally characterized endo and exo [2+4] cycloadducts. According to the calculations, the interconversion of the two conformers can either take place through a return to the pre‐reaction complexes or it can occur by rotation through an intermediate conformation of lesser stability. In view of the stepwise character of the interaction, the possibility that the intermediate zwitterion is the result of the interaction between NBDF and the trans diene could not be excluded. Calculations carried out with the most stable and more populated s‐trans conformer confirmed this idea and supported the role of the zwitterion in the overall interaction.
A Highly Selective, Cell‐Permeable Fluorescent Nanoprobe for Ratiometric Detection and Imaging of Peroxynitrite in Living Cells
Authors: Tian Jiangwei , Chen Huachao , Zhuo Linhai , Xie Yanxia , Li Na , Tang Bo
Published: May 2011

Peroxynitrite (ONOO−) is a highly reactive species implicated in the pathology of numerous diseases and there is currently great interest in developing fluorescent probes that can selectively detect ONOO− in living cells. Herein, a polymeric micelle‐based and cell‐penetrating peptide‐coated fluorescent nanoprobe that incorporates ONOO− indicator dye and reference dye for the ratiometric detection and imaging of ONOO− has been developed. The nanoprobe effectively avoids the influences from enzymatic reaction and high‐concentration .OH and ClO−. The improved ONOO− selectivity of the nanoprobe is achieved by a delicate complementarity of properties between the nanomatrix and the embedded molecular probe (BzSe‐Cy). This nanoprobe also has other attractive properties, such as good water solubility, photostability, biocompatibility, and near‐infrared excitation and emission. Fluorescence imaging experiments by confocal microscopy show that this nanoprobe is capable of visualizing ONOO− produced in living cells and it exhibits very low toxicity and good membrane permeability. We anticipate that this technique will be a potential tool for the precise pathological understanding and diagnosis of ONOO−‐related human diseases.
The Role of the N‐Terminal Domain in the Regulation of the “Constitutively Active” Conformation of Protein Kinase CK2α: Insight from a Molecular Dynamics Investigation
Authors: Cristiani Andrea , Costa Giorgio , Cozza Giorgio , Meggio Flavio , Scapozza Leonardo , Moro Stefano
Published: May 2011

Protein kinase CK2 is an extremely well‐conserved pleiotropic protein kinase with a growing list of substrates, the majority of which are proteins implicated in signal transduction, gene expression, and transcription‐related functions. Protein kinase CK2 is a ubiquitous heterotetrameric serine/threonine protein kinase made up of two α or α’ catalytic subunits and two β regulatory subunits. Moreover, protein kinase CK2 is defined as a “constitutively active” protein kinase in contrast to most other protein kinases characterized by the presence of distinct conformations associated with the active and inactive states. As previously demonstrated by in vitro mutation studies, CK2 activity is substantially regulated by the interaction between the N‐terminal tail and the kinase domain. In fact, progressive deletions of the N‐terminal tail show a decrease in the activity of the kinase. Even if the detrimental effects of Δ2–12 deletion can be partially reversed by the addition of a CK2β subunit, deletions Δ2–12 and Δ2–30 progressively decrease the basal activity of CK2. In particular, as experimentally demonstrated, the Δ2–12 N‐terminal deletion affects both the KM value for ATP and for the substrate peptide, and the kcat value of CK2α. In this work, molecular dynamics (MD) simulations were carried out on wild‐type (wt), Δ2–12 and Δ2–30 deletion mutants of CK2α in order to explore the role of the N‐terminal tail on the conformational behavior of CK2. Furthermore, classical MD simulations were carried out to assess the anticipated impact of conformational changes in a novel set of CK2α mutant forms, such as the triple mutant Y206F‐R10A‐Y261F and the single mutant Y125F.
The Capacity to See Things from the Child's Point of View—Assessing Insightfulness in Mothers with and without a Diagnosis of Depression
Authors: Quitmann Julia H. , Kriston Levente , Romer Georg , Ramsauer Brigitte
Published: May 2011

Insightfulness is seen as the mental capacity that provides the context for a secure child–parent attachment. It involves the ability to see things from the child's perspective and is based on insight into the child's motives, a complex view of the child and openness to new information about the child. To test our hypothesis that maternal insightfulness is related to maternal depression, we utilized the Insightfulness Assessment (IA) developed by Oppenheim and Koren‐Karie to conduct and analyse interviews in which mothers discussed their perceptions of video segments of their interactions with their children. We compared the results of a control group of 30 mothers without a diagnosis of depression with a sample of 23 mothers diagnosed with depression (International Classification of Diseases, 10th Revision). As expected, depression was negatively related to maternal insightfulness.

Oppenheim and Koren‐Karie have argued that the IA might be used as a diagnostic instrument; our work suggests that the IA might show ways of aiding mothers in improving the quality of mother–infant interaction while they are being treated for depression. Copyright © 2011 John Wiley & Sons, Ltd.

Key Practitioner Message

Insightfulness is seen as the mental capacity that provides the context for a secure child–parent attachment.

Maternal depression was negatively related to maternal insightfulness.

The Insightfulness Assessment might be used as a diagnostic instrument.

The Insightfulness Assessment might show ways of aiding mothers in improving the quality of mother‐infant interaction while they are being treated for depression.
Bisquinoxaline‐Fused Porphyrins for Dye‐Sensitized Solar Cells
Authors: Imahori Hiroshi , Iijima Hiroaki , Hayashi Hironobu , Toude Yuuki , Umeyama Tomokazu , Matano Yoshihiro , Ito Seigo
Published: May 2011

5,10,15,20‐Tetrakis(2,4,6‐trimethylphenyl)‐6′‐carboxylquinoxalino[2,3‐b]quinoxalino[12,13‐b′]porphyrinatozinc(II) (ZnPBQ) is synthesized to evaluate the effects of π elongation of quinoxaline‐fused porphyrins on the optical, electrochemical, and photovoltaic properties. ZnPBQ showed an intensified Soret band as well as red‐shifted Soret and Q bands relative to 5,10,15,20‐tetrakis(2,4,6‐trimethylphenyl)‐6′‐carboxylquinoxalino[2,3‐b]porphyrinatozinc(II) (ZnPQ), demonstrating the improved light‐harvesting property of ZnPBQ. The optical and electrochemical HOMO–LUMO gaps were consistent with those estimated by DFT calculations. The photovoltaic properties were compared under optimized conditions, in which a sealed device structure with TiCl4‐treated, TiO2 double layers was used. The ZnPBQ cell exhibited a relatively high power conversion efficiency (η) of 4.7 %, which was smaller than that of the ZnPQ cell (η=6.3 %). The weaker electronic coupling between the LUMO of ZnPBQ and conduction band (CB) of TiO2 or more tilted geometry of ZnPBQ on the TiO2 surface may result in the low electron injection/charge collection efficiency as well as the low incident photon‐to‐current efficiency (IPCE) for the ZnPBQ cell (maximum IPCE=56 %) relative to the ZnPQ cell (maximum IPCE=75 %), leading to the lower η value of the ZnPBQ cell than that of the ZnPQ cell. In addition, the open‐circuit potential of the ZnPBQ cell also slightly decreased with the effect of charge recombination from the electrons injected into the CB of TiO2 to I3−.
Toxoplasmosis in a post‐transplant bronchoalveolar lavage: A case report
Authors: Monaco Sara E. , Monaghan Sara A. , Stamm Jason A. , Khalbuss Walid E. , Nichols Larry , Pantanowitz Liron
Published: May 2011

Toxoplasma gondii usually causes an asymptomatic and then latent infection in human adults; however, a potentially fatal disseminated form can occur in immunocompromised patients. Given that the diagnosis of acute Toxoplasma infection, as opposed to latent disease, relies on finding direct evidence of T. gondii infection in tissue, pathologic examination is critical. There have only been a few reports describing the cytomorphology of Toxoplasma in exfoliative cytology, and no reports of the findings in Thin Prep. In this report, we describe a fatal case of toxoplasmosis in a cardiac transplant patient that was diagnosed by respiratory cytopathology. Although the extracellular organisms were well visualized on the Wright‐Giemsa stained cytospin, they were only faintly seen on the Pap‐stained cytospin trapped within mucin and were not easily appreciated on the ThinPrep slides nor the H&E stained cell block sections. An immunohistochemical stain for Toxoplasma performed on the cell block was strongly positive, and an autopsy performed on the patient confirmed disseminated infection. Our case illustrates that the diagnosis of Toxoplasma in exfoliative cytology specimens can be challenging since organisms are not well visualized on ThinPrep or Pap‐stained material; therefore, Wright‐Giemsa stained material can be particularly helpful. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.
Imidozirconocene‐Mediated Ring Cleavage of Epoxides – Evidence for Bifunctional Reactivity from DFT
Authors: Senthilnathan Dhurairajan , Venuvanalingam Ponnambalam
Published: May 2011

The ring cleavage of epoxides mediated by bis(cyclopentadienyl)(tert‐butylimido)zirconium (Cp2Zr=N–tBu)(THF) has been investigated using DFT calculations with a view to understand the mechanism of epoxide ring cleavage and the role of the imidozirconocene complex. Two types of epoxides have been chosen; some with and some without accessible β‐hydrogen atoms. Epoxides without accessible β‐hydrogen atoms undergo only insertion, whereas those with undergo both insertion and elimination. Although insertion is found to follow a zwitterionic mechanism, the elimination passes through a concerted intramolecular hydrogen transfer step. The role of the imidozirconocene complex has been elucidated by EDA and NBO analysis, which show that the vacant 1a1molecular orbital of the Lewis acidic metal center of Cp2Zr=N–tBu fragment initiates the reaction as a Lewis acidic center and the Lewis basic imido nitrogen atom of the Cp2Zr=N–tBu fragment completes the reaction. The coordinate to covalent bond conversion and the involvement of the 1a1and 2a1molecular orbitals of the Cp2Zr=N–tBu fragment in the reaction have been examined. The formation of a five‐membered metallacycle in the insertion and the alkoxy allyl product in the elimination predicted by calculations concur with experimental observations. Topological analysis has been carried out to further elucidate the mechanism and to reveal the bifunctional reactivity of imidozirconocene in epoxide ring opening reactions.
Synthesis, Characterization and Catalytic Application of Iron Complexes Modified by Monodentate Phosphane Ligands
Authors: Haberberger Michael , Irran Elisabeth , Enthaler Stephan
Published: May 2011

In the present study, the properties of new monodentate phosphane ligands with a N,N‐diphenyl‐1H‐pyrrol‐1‐amine moiety have been investigated. The ligands are easily accessible by lithiation of N,N‐diphenyl‐1H‐pyrrol‐1‐amine in the 2‐position and by quenching with phosphane chlorides (2: R = tBu, 3: R = Ph). After characterization of the ligands, their coordination to iron carbonyls has been studied. The ligands coordinate through the phosphorus in a monodentate fashion to the iron to realize complexes with the (L)Fe(CO)4 motif. Initial catalytic experiments have been performed; the iron‐catalyzed reduction of alkynes to alkenes with excellent selectivities to the corresponding alkenes has been achieved.
Determination of the adulteration of butter
Authors: Derewiaka Dorota , Sosińska Ewa , Obiedziński Mieczysław , Krogulec Aleksandra , Czaplicki Sylwester
Published: May 2011

The adulteration of butter is a serious problem due to economic advantages taken by replacing expensive milk fat with cheaper oil without informing the customers. The authentication of milk fat methods include analysis of bulk components, especially triacylglycerols, fatty acids, sterols and tocopherols. Fatty acid and sterol composition was analysed by using GC‐MS. TAG and tocopherol profiles were examined by HPLC with diode array (DAD) and fluorescence detectors (FLDs). In addition, identification of selected TAG of butter fat was conducted by LC‐atmospheric pressure chemical ionisation (APCI)/MS technique. The lipid composition of 16 different butters available on Polish market were investigated. The cholesterol content in butter fat ranged from 176.8 to 264.8 mg/100 g of fat and in two samples of milk fat β‐sitosterol was found. The total saturated fatty acid (SFA) content in milk fat was 67.1–73.5%, monounsaturated fatty acid 24.5–30.5% and polyunsaturated fatty acid was 1.2–2.0%. Abnormalities in fatty acid profiles, e.g. high concentration of linoleic fatty acid, were found in two butters. These abnormalities were also determined in TAG profiles. The examination of tocopherols in butter fat confirmed that two products were adulterated by the addition of plant oils because they contained δ‐tocopherol which is typical for plant origin foodstuffs. The methods described are useful for investigating milk fat adulterations, and the most efficient are analysis of sterols and tocopherols composition.

Practical applications: The described methods are useful for investigating adulteration of milk fat. Traditional strategies rely on examination of fatty acids methyl esters and TAG; these methods have some disadvantages. Due to the variability of fatty acid composition of milk fat and because TAG analysis is complex and time consuming, FA analysis is not an efficient approach for butter authentication. The most efficient method for butter authentication is qualitative and quantitative analysis of sterols and tocopherols. This analysis will determine if components of plant origin were used for butter production.
Chiral Thiourea‐Catalyzed Asymmetric Michael Addition of β‐Oxo Phosphonate to Nitro Olefins: Convenient Synthesis of Optically Active β‐Oxo Phosphonates
Authors: Hu Kuang , Liu Tao , Lu A. D. , Liu Yunfeng , Wang Youming , Wu Guiping , Zhou Zhenghong , Tang Chuchi
Published: May 2011

β‐Oxo phosphonates have been proven to be alternative Michael donors in Michael addition reactions to nitro olefins in the presence of cinchonine‐based bifunctional thiourea, affording a direct and atom‐economic approach to the efficient construction of synthetically and biologically valuable chiral acyclic α‐substituted β‐oxo phosphonates with high levels of enantioselectivity (up to 98 % ee).
Cyclization Reaction of 2‐Azido‐1‐(2‐hydroxyphenyl)ethanones with Terminal Alkynoates Catalyzed by 4‐Dimethylaminopyridine (DMAP): Synthesis of 2‐Aminobenzofuran‐3(2H)‐one Derivatives
Authors: Meng Ling‐Guo , Ge Ni‐Lin , Yang Ming‐Ming , Wang Lei
Published: May 2011

An unexpected cyclization reaction of 2‐azido‐1‐(2‐hydroxyphenyl)ethanones with terminal alkynoates catalyzed by 4‐dimethylaminopyridine (DMAP) was developed, and 2‐aminobenzofuran‐3(2H)‐one derivatives were obtained in moderate to good yields under mild reaction conditions within 2 h. The scope and limitations of the cyclization reactions were also investigated.
Cooperative Catalysis for the First Asymmetric Formal [3+2] Cycloaddition Reaction of Isocyanoacetates to α,β‐Unsaturated Ketones
Authors: Arróniz Carlos , Gil‐González Alberto , Semak Vladislav , Escolano Carmen , Bosch Joan , Amat Mercedes
Published: May 2011

A cooperative multicatalytic cascade sequence involving isocyanoacetates and α,β‐unsaturated ketones is described for the enantioselective synthesis of 2,3‐dihydropyrroles. The key to promoting the multistep asymmetric reaction is the combination of cinchona alkaloid derived organocatalysts with silver nitrate. Merging both organic and metal catalytic cycles enables the formation of two C–C bonds and the generation of a stereogenic center in a single process. The study has also shown that the bifunctional role of the organocatalyst is crucial for the asymmetric version of the cycloaddition reaction.
Simultaneous Determination of Copper(II), Lead(II) and Zinc(II) at Bismuth Film Electrode by Multivariate Calibration
Authors: Alves Georgina M. S. , Magalhães Júlia M. C. S. , Soares Helena M. V. M.
Published: May 2011

In this work, simultaneous determination of Cu(II), Pb(II) and Zn(II) ions at low concentration levels (ppb) by square wave anodic stripping voltammetry on a Bi(III) film electrode plated in situ at a glassy carbon electrode (GCE) is described. A chemometric approach was used to overcome the overlapping peaks of Cu(II) and Bi(III), the competition of the electrodeposited Cu and Bi for the surface of the GCE and the formation of Cu‐Zn intermetallic compounds. The construction of the multivariate calibration models, based on partial least squares regression, allowed the simultaneous determination of Cu (in the concentration range 8.0 to 20.1 ppb), Pb (2.0 to 30.0 ppb) and Zn (29.7 to 90.4 ppb) with most of the prediction errors obtained in the external validation set for the three models lower than 16, 11 and 26 %, respectively. Finally, this method was used for the determination of these trace metal ions in surface river water samples with satisfactory results [errors below 10, 5 and 32 % for Cu(II), Pb(II) and Zn(II), respectively].
‘One‐Touch’ Voltammetry of Microparticles for the Identification of Corrosion Products in Archaeological Lead
Authors: Doménech‐Carbó Antonio , Doménech‐Carbó María Teresa , Peiró‐Ronda MªAmparo
Published: May 2011

Voltammetry of microparticles is applied to the identification of lead corrosion products by means of an essentially non‐invasive ‘one‐touch’ technique based on the use of graphite pencil. This methodology permits the mechanical attachment of few nanograms of sample from the surface of lead archaeological artefacts to a paraffin‐impregnated graphite electrode, which, upon immersion in aqueous electrolytes, provides distinctive voltammetric responses for litharge and cotunnite‐ anglesite‐, cerusite‐based corrosion products. The reported method is applied to the identification of corrosion products in archaeological lead pieces from different Iberian sites in Valencia (Spain).
Monoseptic growth of fungal lipase producers under minimized sterile conditions: Cultivation of Phialemonium curvatum in 350 L scale
Authors: Barig Susann , Alisch Romy , Nieland Susanne , Wuttke Anne , Gräser Yvonne , Huddar Mahesh , Schnitzlein Klaus , Stahmann Klaus‐Peter
Published: May 2011

A disadvantage of most microbial production processes is the need for sterile techniques. The objective of this study was the development of a robust fungal system allowing monoseptic growth with a minimum of sterile technique in plastic barrels. Selective growth conditions were achieved by mineral salts medium, known for the cultivation of Botrytis cinerea, but containing rapeseed oil instead of glucose as the sole source of carbon and energy. Furthermore, pH 3 was adjusted. A screening of fungi suitable for that system revealed Phialemonium curvatum AW02 isolated from compost. P. curvatum AW02 was superior in comparison with four further fungal isolates because high titers of hydrophilic spores were found in submerged production. Second, a biofilm formation on plastic segments or moving beds made harvesting of the biomass comfortable. Cultivations with volumes of 100 or 350 L showed no contaminations by bacteria when all conditions were controlled. Two independent approaches showed the dependance of growth on lipases in the cultivation system. A B. cinerea strain knocked out in lip1 showed reduced growth in comparison to the wild type because the first catabolic step is the triglyceride hydrolysis. P. curvatum AW02 lipase activity was detected. More than 90% was found to be cell wall associated. Solid shear stress liberated two active proteins showing IEPs of 4.7 or 5.6.
Simulation of orthogonal horizontal ground motion components for specified earthquake and site characteristics
Authors: Rezaeian Sanaz , Der Kiureghian Armen
Published: May 2011

A method for generating an ensemble of orthogonal horizontal ground motion components with correlated parameters for specified earthquake and site characteristics is presented. The method employs a parameterized stochastic model that is based on a time‐modulated filtered white‐noise process with the filter having time‐varying characteristics. Whereas the input white‐noise excitation describes the stochastic nature of the ground motion, the forms of the modulating function and the filter and their parameters characterize the evolutionary intensity and nonstationary frequency content of the ground motion. The stochastic model is fitted to a database of recorded horizontal ground motion component pairs that are rotated into their principal axes, a set of orthogonal axes along which the components are statistically uncorrelated. Model parameters are identified for each ground motion component in the database. Using these data, predictive equations are developed for the model parameters in terms of earthquake and site characteristics and correlation coefficients between parameters of the two components are estimated. Given a design scenario specified in terms of earthquake and site characteristics, the results of this study allow one to generate realizations of correlated model parameters and use them along with simulated white‐noise processes to generate synthetic pairs of horizontal ground motion components along the principal axes. The proposed simulation method does not require any seed recorded ground motion and is ideal for use in performance‐based earthquake engineering. Copyright © 2011 John Wiley & Sons, Ltd.