bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic Electrophilic Halogenation of Silyl‐Protected and Terminal Alkynes: Trapping Gold(I) Acetylides vs. a Brønsted Acid‐Promoted Reaction
Authors: Starkov Pavel , Rota Filippo , D'Oyley Jarryl M. , Sheppard Tom D. 
Published: November 2012

AbstractIn the presence of a cationic gold(I) catalyst and N‐halosuccinimide, both trimethylsilyl‐protected and terminal alkynes are converted into alkynyl halides. Further experiments showed that silyl‐protected alkynes undergo electrophilic iodination and bromination under Brønsted acid catalysis, whilst terminal alkynes require a cationic gold catalyst. The former reactions probably proceed via activation of the electrophile, whilst the latter reactions proceed via a gold(I) acetylide intermediate. Gold‐catalysed halogenation was further combined with gold‐catalysed hydration and subsequent annulation to provide convenient routes to iodomethyl ketones and five‐membered aromatic heterocycles.
Construction of Contiguous Tetrasubstituted Carbon Stereocenters by Intramolecular Crossed Benzoin Reactions Catalyzed by N‐Heterocyclic Carbene (NHC) Organocatalyst
Authors: Ema Tadashi , Akihara Kumiko , Obayashi Ryoko , Sakai Takashi 
Published: November 2012

AbstractBicyclic compounds with two contiguous tetrasubstituted carbon stereocenters at bridgehead positions were synthesized by N‐heterocyclic carbene (NHC)‐catalyzed intramolecular crossed benzoin reactions of symmetrical compounds. This desymmetrization strategy was applied to asymmetric synthesis with chiral NHC organocatalysts. Transition‐state models were proposed to explain the enantioselectivity. A tricyclic compound with three contiguous tetrasubstituted carbon stereocenters was synthesized by a stepwise strategy. The molecular structure and absolute configuration of the (+)‐enantiomer of this tricyclic compound were determined by X‐ray crystallographic analysis.
Palladium‐Catalyzed CH Bond Acetoxylation: An Approach to ortho‐Substituted Hydroxy[2.2]paracyclophane Derivatives
Authors: Lennartz Petra , Raabe Gerhard , Bolm Carsten 
Published: November 2012

AbstractThe palladium‐catalyzed direct CH bond acetoxylation of [2.2]paracyclophanes has been investigated. Various mono‐ and disubstituted [2.2]paracyclophanes were subjected to typical Sanford acetoxylation conditions. Oxime ethers, an oxime acetate, a pyridine, and a pyrazole with [2.2]paracyclophane cores underwent direct ortho‐acetoxylation in good to excellent yields using 1–5 mol% of palladium(II) acetate in combination with iodobenzene diacetate as oxidant. The reactions could be performed on a multigram scale, and the ortho‐acetoxylated [2.2]paracyclophanes were suitable for further functionalizations affording a hydroxy[2.2]paracyclophane derivative and a planar chiral benzoxazole.
Step‐Economic and Protecting‐Group‐Free Total Synthesis of (+)‐Cardiobutanolide
Authors: Fernandes Rodney A. , Kattanguru Pullaiah 
Published: November 2012

AbstractA short protecting‐group‐free synthesis of (+)‐cardiobutanolide is reported. We have modified a one‐pot conversion of D‐glucono‐δ‐lactone into the building block β‐hydroxy‐γ‐lactone. A series of cross‐metathesis reactions and dihydroxylations either under the Sharpless conditions or achiral 4‐methylmorpholine N‐oxide (NMO) conditions were used to synthesize (+)‐cardiobutanolide and its various diastereomers. In this endeavour, we have achieved a step‐economic and protecting‐group‐free synthesis of (+)‐cardiobutanolide in 22.4 % overall yield from D‐glucono‐δ‐lactone. A cross‐metathesis reaction that is compatible with hydroxy groups and a substrate controlled Upjohn dihydroxylation reaction are key steps in the synthesis. The synthesis is highly efficient and competitive with previous reports.
Cyclodextrin functionalization of several cellulosic substrates for prolonged release of antibacterial agents
Authors: Cusola Oriol , Tabary Nicolas , Belgacem Mohamed Naceur , Bras Julien 
Published: November 2012

AbstractSeveral cellulosic substrates have been surface‐functionalized with cyclomaltoheptaose (β‐cyclodextrin, β‐CD) using citric acid as a crosslinker agent to obtain new surface‐modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on β‐CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug‐delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
On the brink – investigating biodiversity in endangered crater lakes of the Amber Mountains National Park (Madagascar)
Authors: Schabetsberger R. , Kaiser R. , Rott E. , Lenzenweger R. , Traunspurger W. , Kotov A. A. , Fiers F. , Gaviria S. , Meisch C. , Mahunka S. , Campbell R. D. , Razafindranaivo E. , Sztatecsny M. 
Published: November 2012

ABSTRACT

Madagascar's biodiversity is vanishing at an alarming pace. The documentation of this loss has so far focused on terrestrial habitats and organisms. Eight volcanic crater lakes in the Amber Mountains National Park (Northern Madagascar) and surroundings were investigated for the first time to describe limnological conditions and aquatic biodiversity. Seven of the lakes were affected by deforestation/logging and fish introduction and only one lake was assumed to have remained in pristine condition. In the deeper lakes (> 5 m) steep physico‐chemical gradients and anoxic hypolimnia were observed.
Algae, hydrozoans, nematodes, rotifers, annelids, copepods, cladocerans, ostracods, and mites were identified to genus or species level. The majority were taxa with a cosmopolitan or tropicopolitan distribution. The highest number of afrotropical and endemic species were recorded within the crustaceans.
Multivariate analysis of species communities revealed significant differences between lakes in deforested and forested catchments. Introduced alien fish had no detectable effect on species assemblages.
Illegal harvest of timber was observed within the National Park and drug plantations are less than 1 km away from the last pristine crater lake. If deforestation continues at the current rate, which is likely under the prevailing political situation, the last undisturbed lake communities may be altered in the near future.
There is an urgent need for taxonomic research to assess the biodiversity of algae and micrometazoa. Highest priority should be given to pristine freshwater ecosystems within protected areas. Copyright © 2012 John Wiley & Sons, Ltd.
Learning and Affect Following Near‐Miss Outcomes in Simulated Gambling
Authors: Clark Luke , Liu Rui , McKavanagh Rebecca , Garrett Alice , Dunn Barnaby D. , Aitken Michael R. F. 
Published: November 2012

ABSTRACTGambling near‐misses are non‐rewarded events that resemble a winning configuration. Past research using slot machines has shown that moderate rates of near‐misses increase gambling persistence, but the mechanisms supporting this persistence are unclear. One hypothesis is that near‐misses are mistakenly interpreted as signals of skill acquisition, supporting learning and fuelling the ‘illusion of control’. A slot machine simulation was administered to 60 volunteers, with ratings of the perceived chances of winning, pleasure and motivation to play following particular outcomes. Psychophysiological measures (electrodermal activity and heart rate) were taken, and gambling persistence was measured after 30 trials. Near‐misses were similar to full‐miss outcomes in that they were regarded as unpleasant. However, near‐misses were akin to win outcomes in that they increased motivations to play and electrodermal activity. Learning was evidenced by the expectancy of winning increasing following wins and decreasing after losses. Although there was no overall change in expectancy of winning after near‐misses across all participants, those subjects reporting a greater increase in the expectancy of winning following a near‐miss showed more persistent play, consistent with the learning hypothesis. Greater heart rate acceleration following near‐misses was also associated with persistence. We also observed differential effects of near‐misses where the reel stopped either side of the winning position (‘payline’): motivational effects were restricted to near‐misses stopping before the payline, whereas near‐misses that stopped after the payline were primarily aversive. The payline effects are not predicted by the learning hypothesis and may indicate an affective component to near‐misses, possibly linked to counterfactual processing. Copyright © 2012 John Wiley & Sons, Ltd.
Multicentre study of circumferential margin positivity and outcomes following abdominoperineal excision for rectal cancer
Authors: Kennelly R P , Rogers A C , Winter D C 
Published: November 2012

Abstract

Background
Rectal cancer outcomes following abdominoperineal excision (APE) have been inferior to those for anterior resection, including more positive circumferential resection margins (CRMs). An erroneously conservative interpretation of APE (rather than a radical resection termed ‘extralevator’) has been proposed as the cause. In this multicentre study, factors contributing to CRM positivity were examined following APE according to its original description.

Methods
Data were collected from five hospital databases up to June 2011 including small- and larger-volume units (3 hospitals had 5 or fewer and 2 hospitals had more than 5 APE procedures per year). Primary outcome measures were CRM status; secondary outcomes were local recurrence and death.

Results
Of 327 patients, 302 patients had complete data for analysis. Some 50·0 per cent of patients had neoadjuvant chemoradiotherapy. Histopathological examination showed that 62·9 per cent had tumour category T3 or T4 cancers, 42·1 per cent had node-positive disease and the CRM positivity rate was 13·9 per cent. Multivariable analysis showed only pathological tumour category pT4 (odds ratio 19·92, 95 per cent confidence interval 6·48 to 68·61) and node positivity (odds ratio 3·04, 1·32 to 8·05) to be risk factors for a positive circumferential margin. CRM positivity was a risk factor for local recurrence (P = 0·022) and decreased overall survival (P = 0·001). Hospital volume had no impact on the likelihood of CRM positivity (P = 0·435).

Conclusion
In patients undergoing APE by appropriately trained surgeons using a standardized approach, margin positivity was dictated by tumour stage, but not by centre or surgeon.
A Systematic Review of the Differential Diagnosis of Retinal Haemorrhages in Children with Clinical Features associated with Child Abuse
Authors: Maguire Sabine Ann , Lumb Rebecca Caroline , Kemp Alison Mary , Moynihan Sian , Bunting Howard John , Watts Patrick O. , Adams Gillian Gwendolen 
Published: November 2012

Retinal haemorrhages (RH) in a young child suggest child abuse, yet other causes merit consideration. This systematic review addresses non‐traumatic causes of RH in children with one or more overlapping clinical features of abuse (bruising, fractures, intracranial haemorrhage). Searching 12 databases (1950–2009) identified 338 studies for review by two reviewers. Inclusion criteria included: children < 15 years examined by an ophthalmologist detailing retinal findings, confirmed organic cause and exclusion of abuse. Exclusion criteria included: diagnosed coagulopathy, ocular mass lesion and post‐mortem cases. Twenty included studies identified nine relevant conditions (metabolic diseases, bony dysplasias, bleeding disorders and vascular malformations). Where detailed, the RH were bilateral and involved only one area of the retina (the posterior pole). Among proposed confounders of RH, no child with a cough (100 children) or acute life‐threatening event (184 cases) had RH. Just two of 217 children with seizures had posterior pole RH, one unilateral and one bilateral. One cardiopulmonary resuscitation (CPR) study (43 cases) was included where a child with co‐existent clotting abnormalities had tiny (bilateral dot) RH after 60 minutes’ resuscitation. Child abuse remains the commonest cause of RH in young children, although rarer disorders merit consideration. There are insufficient data to conclude that CPR is a confounder in children with RH. Copyright © 2012 John Wiley & Sons, Ltd.‘Searching 12 databases (1950–2009) identified 338 studies for review’‘There are insufficient data to conclude that CPR is a confounder in children with RH’Key Practitioner Message

Retinal Haemorrhages are strongly associated with Abusive Head Trauma, but have been described in certain medical conditions.
Neither cough nor ALTE are associated with RH, which have been found in < 3% of children with seizures. There are inadequate data to conclude that CPR is associated with RH.
Case series have reported RH in children who also have clinical features that may overlap with physical abuse, namely certain metabolic, vascular, haematologic disorders and bony dysplasias (specifically osteogenesis imperfecta).
A Comparison Study between Official Records and Self‐Reports of Childhood Adversity
Authors: Pinto Ricardo J. , Maia Ângela C. 
Published: November 2012

The aim of this paper was to assess the degree and nature of any mismatch between officially recognised child maltreatment and adolescent self‐report of adverse child experiences. Participants included 136 adolescents (72 males, 64 females, Mage = 17 years, age range 14–23 years) who had been confirmed as victims of maltreatment prior to age 13 by Child Protective Services. Participants' self‐reports were obtained in adolescence, at least four years after identification. Physical neglect was the most prevalent experience found in the records (87%, n = 118). When this experience was assessed through self‐report, only 36 per cent (n = 49) of participants reported physical neglect. Sexual abuse was self‐reported by 17 per cent (n = 23) of the sample, compared with eight per cent (n = 11) in the records. Only 17 per cent (n = 23), a small number of self‐reports, were consistent with official records. Kappa values show that agreement is low (under 0.40) for seven of the ten categories. Our findings suggest substantial unreliability in the reporting of child abuse and neglect, including household adverse experiences. They also suggest the failure of professionals to discover several adverse experiences during childhood, even after identification by authorities. Copyright © 2012 John Wiley & Sons, Ltd.‘Only 17 per cent, a small number of self‐reports, were consistent with official records’Key Practitioner Messages

Child protection practitioners need to be aware of multiple experiences that can co‐occur with the suspicion or situation initially reported to child protection agencies.
Little attention is given to protecting children and young people from later re‐victimisation.
The conclusions from the relationship between childhood maltreatment and later outcomes should be approached with caution when retrospective reports or official data are used alone.‘Little attention is given to protecting children and young people from later re‐victimisation’
A Luminescent Cyclometalated Iridium(III) Complex Accumulates in Mitochondria and Induces Mitochondrial Shortening by Conjugation to Specific Protein Targets
Authors: Wang Baojiang , Liang Yimin , Dong Hongjuan , Tan Tianfeng , Zhan Bao , Cheng Jinping , Lo Kenneth Kam‐Wing , Lam Yun Wah , Cheng Shuk Han 
Published: November 2012

AbstractWe report the cellular properties of a luminescent cyclometalated iridium(III) complex, [Ir(pq)2(phen‐ITC)](PF6) (Ir‐ITC; Hpq=2‐phenylquinoline, phen‐ITC=5‐isothiocyanate‐1,10‐phenanthroline), that efficiently and specifically labels mitochondria in living mammalian cells. Ir‐ITC can be covalently conjugated to its protein targets, and its luminescence survived cell lysis, protein extraction, and gel electrophoresis under denaturing conditions. The conjugation of Ir‐ITC with live‐cell proteins is rapid and highly selective; the process requires active cellular metabolism, as the conjugation is abolished at nonphysiological temperature or in the presence of sodium azide. Based on measurements of the luminescence intensity, we have devised a biochemical fractionation procedure that allows the enrichment of the conjugated proteins, and their subsequent separation by two‐dimensional gel electrophoresis (2DGE). Luminescent protein spots were picked from the gel and analyzed by mass spectrometry; this resulted in the identification of 46 proteins. Many of the strongly luminescently labeled proteins are mitochondrial proteins. One of the targets is VDAC1 (voltage‐dependent anion channel 1). Consistent with known phenotypes of VDAC1 deregulation, prolonged exposure of cells to Ir‐ITC led to significant mitochondrial shortening and fragmentation. As far as we know, this is the first report on the molecular characterization of the interactions of a luminescent dye with its biological targets. As many biological dyes exhibit specific intracellular staining patterns, the identification of their molecular targets can help elucidate the mechanisms behind their staining specificities and cytotoxicity. We believe our biochemical approach can be applied to identify the targets of a wide range of fluorescent and luminescent probes.
New Insights into the Biosynthesis of Prenylated Xanthones: Xptb from Aspergillus nidulans Catalyses an O‐Prenylation of Xanthones
Authors: Pockrandt Daniel , Ludwig Lena , Fan Aili , König Gabriele M. , Li Shu‐Ming 
Published: November 2012

AbstractGene‐inactivation experiments have indicated that the putative prenyltransferase XptB from Aspergillus nidulans was likely to be responsible for the prenylation of 1,7‐dihydroxy‐6‐methyl‐8‐hydroxymethylxanthone. Recently, it was suggested that this enzyme might also accept as substrate the benzophenone arugosin H, which is assumed to be a precursor of prenylated xanthones. In this study, five benzophenones and ten xanthones were incubated with purified recombinant XptB in the presence of dimethylallyl diphosphate (DMAPP). XptB accepted four xanthones as substrates, including the proposed natural substrate, and catalysed regiospecific O‐prenylations at C‐7 of the xanthone core. Km values in the range of 0.081–1.1 mM and turnover numbers (kcat) between 0.02 and 0.5 s−1 were determined for the accepted xanthones. The kinetic parameters for DMAPP were found to be 0.024 mM (Km) and 0.13 s−1 (kcat). Arugosin H was not accepted by XptB under the tested conditions. XptB was relatively specific towards its prenyl donor and did not accept geranyl or farnesyl diphosphate as substrate. Mn2+ and Co2+ strongly enhanced XptB activity (up to eightfold); this has not been reported before for prenyltransferases of the DMATS superfamily.
De Novo Design, Synthesis and Characterisation of MP3, A New Catalytic Four‐Helix Bundle Hemeprotein
Authors: Faiella Marina , Maglio Ornella , Nastri Flavia , Lombardi Angela , Lista Liliana , Hagen Wilfred R. , Pavone Vincenzo 
Published: November 2012

AbstractA new artificial metalloenzyme, MP3 (MiniPeroxidase 3), designed by combining the excellent structural properties of four‐helix bundle protein scaffolds with the activity of natural peroxidases, was synthesised and characterised. This new hemeprotein model was developed by covalently linking the deuteroporphyrin to two peptide chains of different compositions to obtain an asymmetric helix–loop–helix/heme/helix–loop–helix sandwich arrangement, characterised by 1) a His residue on one chain that acts as an axial ligand to the iron ion; 2) a vacant distal site that is able to accommodate exogenous ligands or substrates; and 3) an Arg residue in the distal site that should assist in hydrogen peroxide activation to give an HRP‐like catalytic process. MP3 was synthesised and characterised as its iron complex. CD measurements revealed the high helix‐forming propensity of the peptide, confirming the appropriateness of the model procedure; UV/Vis, MCD and EPR experiments gave insights into the coordination geometry and the spin state of the metal. Kinetic experiments showed that FeIII–MP3 possesses peroxidase‐like activity comparable to R38A–hHRP, highlighting the possibility of mimicking the functional features of natural enzymes. The synergistic application of de novo design methods, synthetic procedures, and spectroscopic characterisation, described herein, demonstrates a method by which to implement and optimise catalytic activity for an enzyme mimetic.
Tuning Chloride Binding, Encapsulation, and Transport by Peripheral Substitution of Pseudopeptidic Tripodal Small Cages
Authors: Martí Inés , Rubio Jenifer , Bolte Michael , Burguete M. Isabel , Vicent Cristian , Quesada Roberto , Alfonso Ignacio , Luis Santiago V. 
Published: November 2012

AbstractA highly efficient synthesis of small pseudopeptidic cages from simple precursors has been achieved by the triple SN2 reaction between tripodal tris(amido amines) and several 1,3,5‐tris(bromomethyl)benzene electrophiles. The success of the macrobicyclization strongly depends on the central triamine scaffold, which dictates the correct preorganization of the intermediates. The chloride binding properties of the protonated pseudopeptidic cages have been studied in the solid state (by X‐ray diffraction) as well as in solution (by NMR spectroscopy and ESI‐MS) and in the gas phase (by collision‐induced dissociation (CID)‐MS). The crystal structure of the HCl salts of several cages show a chloride partially or completely caged within the cavity of the macrobicycle. Both the amino acid side chain and the substitution at the aromatic tripodal ring have an effect on the chloride binding ability. The cages derived from the 1,3,5‐benzene moiety show low affinity, whereas the triple substitution in the ring (either with Me or Et) increases the chloride binding by one order of magnitude. Besides, the cages derived from aliphatic amino acids display a stronger interaction than those derived from phenylalanine. The basis for the different mode of binding depending on the receptor structure is proposed according to the structural data (X‐ray and NMR spectroscopy). Finally, the transport of the chloride anion through lipid bilayers has been studied for selected cages. Despite the important differences in the chloride binding, the transport properties are better correlated with the lipophilicity of the molecules. Therefore, the pseudopeptidic cages sharing the same binding motif for chloride rendered very different interaction and transport properties depending on the peripheral substitution.