bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk-adjusted predictive models of mortality after index arterial operations using a minimal data set
Authors: Prytherch D R , Ridler B M F , Ashley S 
Published: April 2005

Abstract

Background
Reducing the data required for a national vascular database (NVD) without compromising the statistical basis of comparative audit is an important goal. This work attempted to model outcomes (mortality and morbidity) from a small and simple subset of the NVD data items, specifically urea, sodium, potassium, haemoglobin, white cell count, age and mode of admission.

Methods
Logistic regression models of risk of adverse outcome were built from the 2001 submission to the NVD using all records that contained the complete data required by the models. These models were applied prospectively against the equivalent data from the 2002 submission to the NVD.

Results
As had previously been found using the P-POSSUM (Portsmouth POSSUM) approach, although elective abdominal aortic aneurysm (AAA) repair and infrainguinal bypass (IIB) operations could be described by the same model, separate models were required for carotid endarterectomy (CEA) and emergency AAA repair. For CEA there were insufficient adverse events recorded to allow prospective testing of the models. The overall mean predicted risk of death in 530 patients undergoing elective AAA repair or IIB operations was 5·6 per cent, predicting 30 deaths. There were 28 reported deaths (χ2 = 2·75, 4 d.f., P = 0·600; no evidence of lack of fit). Similarly, accurate predictions were obtained across a range of predicted risks as well as for patients undergoing repair of ruptured AAA and for morbidity.

Conclusion
A ‘data economic’ model for risk stratification of national data is feasible. The ability to use a minimal data set may facilitate the process of comparative audit within the NVD.
Randomized clinical trial of laparoscopic Roux-en-Y gastric bypass versus laparoscopic vertical banded gastroplasty for obesity
Authors: Olbers T , Fagevik-Olsén M , Maleckas A , Lönroth H 
Published: April 2005

Abstract

Background
Laparoscopic techniques have been developed for performing Roux-en-Y gastric bypass (LRYGBP) and vertical banded gastroplasty (LVBG) in patients with morbid obesity. It is not certain, however, which is the better technique in non-superobese patients (body mass index less than 50 kg/m2).

Methods
Eighty-three patients (LRYGBP 37, LVBG 46) were assessed in a randomized clinical trial. Perioperative complications were recorded together with preoperative and postoperative respiratory function and mobilization rate. Patients were monitored for 2 years after operation with regard to weight change and the need for remedial surgery.

Results
There were no conversions to open surgery. The mean operating time was longer for LRYGBP than LVBG (138 versus 105 min). Five early reoperations were performed after LRYGBP (three for haemorrhage, one for ileus and one suspected leak) and one after LVBG (suspected leak). There were no differences in postoperative respiratory function or mobilization. Weight reduction was greater after LRYGBP (excess weight loss 78·3 versus 62·9 per cent 1 year after surgery, P = 0·009; 84·4 versus 59·8 per cent at 2 years, P &lt; 0·001). Remedial surgical intervention was required in eight patients after LVBG (conversion to Roux-en-Y gastric bypass) and none after LRYGBP.

Conclusion
LRYGBP and LVBG were comparable in terms of operative safety and postoperative recovery, but weight reduction was better after LRYGBP.
Percutaneous treatment of superior vena cava obstruction following transvenous device implantation
Authors: Bolad Islam , Karanam Sree , Mathew Dilip , John Roy , Piemonte Thomas , Martin David 
Published: April 2005

AbstractThe aim of this study is to assess the feasibility and safety of percutaneous treatment of superior vena cava (SVC) obstruction following transvenous device implantation. SVC obstruction is an uncommon but serious complication that can occur following permanent pacemaker or cardioverter defibrillator implantation utilizing transvenous endocardial leads. The treatment has traditionally been surgical but with the advent of stents, percutaneous approach is becoming popular. We report on the prevalence of SVC obstruction and the safety of its percutaneous catheter‐based treatment. This is a retrospective study of SVC obstruction following device implantation in our institution from January 1993 through November 2003. A total of 1,850 permanent pacemaker and 1,200 implantable cardioverter defibrillator initial implants were performed during that period. Three patients developed SVC obstruction following implant (prevalence, 1/1,000 implant). Two patients were males and the mean age at implant was 57 ± 13 years. Laser lead extraction and SVC angioplasty with or without stenting were performed in all patients. In two of them, this was followed by reimplantation of new systems. There were no procedural complications or mortality. The patients remain free of SVC obstruction symptoms 24 ± 19 months after treatment. SVC obstruction prevalence after device implantation is low. Percutaneous treatment of SVC obstruction can be safely performed and appears to be effective in maintaining medium‐term patency. © 2005 Wiley‐Liss, Inc.
Simultaneous kissing drug‐eluting stent technique for percutaneous treatment of bifurcation lesions in large‐size vessels
Authors: Sharma Samin K. 
Published: April 2005

AbstractTreatment of bifurcation lesions is associated with high procedural complications and restenosis rate due to plaque shift, suboptimal angiographic results, difficulty in crossing the stent struts, and incomplete coverage of the side‐branch ostium. The simultaneous kissing stent (SKS) technique involves two stents, one in main vessel (MV) and one in the side branch (SB) with overlapping stents in the MV proximally, extending proximally the carina of bifurcation. We analyzed our first 200 consecutive patients (202 lesions) who underwent SKS technique for true bifurcation lesions using sirolimus eluting stents, with a minimum follow‐up of 6 months. Procedural success was 100% for MV and 99% for SB using SKS technique, with clinical success rate of 97%. In‐hospital and 30‐day major adverse cardiac events were 3% and 5%, respectively, with a procedure time of 36 ± 14 min. At mean follow‐up of 9 ± 2 months, the incidence of target lesion revascularization was 4% in the entire group. Therefore, SKS technique using sirolimus‐eluting stents may become an effective treatment strategy for large‐size bifurcation lesions. However, in order to establish its superiority, SKS technique needs to be compared in a randomized manner with conventional stent techniques. © 2005 Wiley‐Liss, Inc.
Intramolecular Versus Intermolecular Induction of Helical Handedness in Pyridinedicarboxamide Oligomers
Authors: Maurizot Victor , Dolain Christel , Huc Ivan 
Published: April 2005

AbstractA new convergent synthetic scheme has been developed to prepare oligoamides of 2,6‐diaminopyridine and 4‐decyloxy‐2,6‐pyridinedicarboxylic acid. These compounds adopt stable single helical conformations in solution. NMR and circular dichroism studies show that intramolecular and intermolecular chiral induction of handedness in these helices is possible. Intramolecular induction is effected by attaching a single chiral group to the end of an oligomer. Intermolecular induction results from various noncovalent interactions between chiral carboxylic or sulfonic acids and the terminal residues of the oligoamides. Intramolecular induction appears to be more efficient than intermolecular induction. When both effects compete, intramolecular induction prevails. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Towards In‐Plane Delocalized 4N/7e Radical Cations and 4N/6e Dications – One‐/Two‐Electron Oxidation of Proximate‐Parallel Bis(N,N'‐bicyclic)‐bishydrazines
Authors: Exner Kai , Heizmann Markus , Yang Fushun , Kegel Markus , Keller Manfred , Knothe Lothar , Großmann Birgit , Heinze Jürgen , Prinzbach Horst 
Published: April 2005

AbstractIn the pursuit of novel bishomoconjugated (σ‐bishomoaromatic) 4N/7(6)e bonding motifs, (bisseco)pagodane/isopagodane and dodecahedrane‐like, caged, proximate‐parallel bishydrazines have been designed as suitable host skeletons. The derived radical cations and dications are characterized by calculations as cyclically in‐plane delocalized (σ‐bishomoaromatic) species (4N/7(6)e). However, the synthetic approaches based on a pool of half‐caged proximate‐parallel bisdiazenes/bishydrazines and on strategies in part elaborated in the pagodane area have not led to the target structures. Half‐caged, rather flexible bis(N,N'‐bicyclic) bishydrazines (9,10) evolved as the structurally closest synthetically accessible model compounds. Whilst CV (PE, ESR)measurements were not suggestive of significant through‐space interaction in the respective radical cations and dications, DFT calculations (B3LYP/6‐31G*) identified a singlet dication (102+) as proximate, cyclically in‐plane delocalized species, which, however, relaxed into a more stable, more distant triplet. In an Appendix, selected examples are presented for the synthetic utilization of proximate‐parallel bisdiazenes (bishydrazines) in the area of more or less preorganized, semi‐ to fully caged tetra(hexa)azapolycyclic molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis and Characterization of Some Aza[5]helicenes
Authors: Bazzini Cristina , Brovelli Sergio , Caronna Tullio , Gambarotti Cristian , Giannone Matteo , Macchi Piero , Meinardi Francesco , Mele Andrea , Panzeri Walter , Recupero Francesco , Sironi Angelo , Tubino Riccardo 
Published: April 2005

AbstractA systematic study on the synthesis and properties of aza‐[5]helicenes bearing one or two nitrogen atoms in selected ring positions is reported for the first time. This photochemical approach can be conveniently applied to the preparation of either mono‐ or diaza[5]helicenes. The aza[5]helicenes were characterized by NMR spectroscopy, X‐ray crystallography, emission spectroscopy, and luminescence lifetime. The extremely long triplet lifetime observed (in the range of seconds) makes these molecules promising candidates for practical applications in photo‐ and optoelectronics. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The Effect of Charge‐Transfer Complexation/π‐Stacking Interactions in Lowering the Activation Barrier of the Bergman Cyclization
Authors: Basak Amit , Bag Subhendu Sekhar , Das Amit K. 
Published: April 2005

AbstractTo elaborate the concept of weak interactions and their effect on Bergman Cyclization (BC), several 1,2‐dikynyl benzenes incorporating various combinations of donor and acceptor units in the two arms of the enediynes were designed and synthesized, and their charge‐transfer interactions followed by UV/Vis spectroscopy. The thermal reactivities, as studied by DSC, show an increase in reactivity for the donor/acceptor or donor/donor combinations relative to the acceptor/acceptor pair. Such an increase in reactivity can be explained on the basis of intramolecular charge transfer and π‐stacking interactions between the two arms, which may lower the distance between the two acetylenic ends. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Iridium‐Catalyzed H/D Exchange
Authors: Krüger Jens , Manmontri Boripont , Fels Gregor 
Published: April 2005

AbstractThe scope and limitation of an iridium‐catalysed H/D exchange reaction has been investigated. Our results suggest a general mechanism for specific labelling at aromatic and non‐aromatic double bonds by D2O if an electron‐donating group is in a 1,4‐relation with the carbon where the H/D exchange takes place. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Organolithium/Chiral Lewis Base/BF3: a Versatile Combination for the Enantioselective Desymmetrization of meso‐Epoxides
Authors: Vrancken Emmanuel , Alexakis Alexandre , Mangeney Pierre 
Published: April 2005

AbstractBF3 can be used in combination with organolithium/strong Lewis base complexes for the enantioselective nucleophilic ring‐opening or the carbenoidic rearrangement of various meso‐oxiranes with excellent yields and ee values of up to 87 %. Mechanistic aspects of these reactions are considered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Asymmetric Dihydroxylation with Recoverable Cinchona Alkaloid Derivatives: A Warning Note and an Improved, Insoluble Polymer‐Bound Ligand Architecture
Authors: Mandoli Alessandro , Pini Dario , Fiori Massimo , Salvadori Piero 
Published: April 2005

AbstractThe nature of catalytic asymmetric dihydroxylation (AD), in particular the problem of ligand leaching from insoluble polymer‐bound (IPB) Cinchona alkaloid derivatives, has been investigated. An upper limit to the amount of dissolved ligand, and methods for its evaluation, which assure a basically heterogeneous character of the observed AD reaction, are presented. A new copolymer architecture, which meets the established stability requirements and allows the highly enantioselective (87–99 % ee) IPB‐AD of representative alkene substrates, is also described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
DNA Binding of a Molecular‐Scale Receptor in the Presence of Zinc(II) Ions
Authors: Benniston Andrew C. , Harriman Anthony , Lawrie Donald J. , Mehrabi Maryam 
Published: April 2005

AbstractThe properties of a tritopic artificial biological probe are described. This probe consists of a luminescent pyrene–thiophene unit connected by an ethynylene group to a 2,2':6',2‐terpyridine (terpy) cation binding site. The pyrene unit, as evidenced by fluorescence spectroscopy under illumination at 400 nm, is capable of intercalating into double‐stranded calf‐thymus DNA in H2O (buffered, pH = 7.0) at 25 °C. The binding constant K was calculated to be 6.0 × 105M–1. Titration of zinc(II) ions in an aqueous (pH = 7.0) solution containing the intercalated probe results in fluorescence quenching which again is a consequence of the zinc(II) ions binding to the terpy site. The DNA‐bound probe has also been shown to undergo singlet energy transfer to intercalated ethidium bromide with a rate constant of 9.4 × 109 s–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Recent Advances in the Total Synthesis of Piperidine Azasugars
Authors: Pearson Morwenna S. M. , Mathé‐Allainmat Monique , Fargeas Valérie , Lebreton Jacques 
Published: April 2005

AbstractSince the discovery of nojirimycin, a glycosidase inhibitor, polyhydroxylated piperidines (also called azasugars: the ring O‐atom of a carbohydrate is replaced by nitrogen) have attracted considerable attention and have been the target of numerous synthetic strategies during the last decade. The efficient synthesis of naturally occurring azasugars and their analogs is of considerable importance due to their potential glycosidase inhibitor properties. Some of them have been widely investigated as candidates for drugs to treat a variety of carbohydrate‐mediated diseases such as diabetes, viral infections, including HIV, cancer metastasis, hepatitis, and Gaucher’s disease. This microreview focuses on recent syntheses of azasugars. In addition, the biology of these compounds is briefly considered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Novel Approach to the (–)‐Sparteine‐Mediated Synthesis of Kainoids:Total Synthesis of (–)‐α‐Kainic Acid by (–)‐Sparteine‐Mediated Deprotonation
Authors: Montserrat Martínez M. , Hoppe Dieter 
Published: April 2005

AbstractWe report a new synthesis of kainoids via allyllithium compounds using an intramolecular cycloalkylation as the key step. Preparation of different substituted pyrrolidines was carried out by using carbamates, that react with the chiral base n‐BuLi/(–)‐sparteine with strong selection between the diastereotopic protons adjacent to the carbamate group in favour for the pro‐S proton. (–)‐α‐Kainic acid was synthetized from D‐serine methyl ester hydrochloride, based on a (–)‐sparteine‐mediated asymmetric deprotonation of an intermediate carbamate that, by stereospecific anti‐SN′SE′ intramolecular cycloalkylation, leads to the pyrrolidine ring precursor of (–)‐α‐kainic acid, in high yield and diastereoselectivity. Related approaches, starting from L‐glutamic acid failed. The intermediate pyrrolidine was further transformed to (–)‐α‐kainic in three steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cover Picture: Synthesis and Characterization of Some Aza[5]helicenes (Eur. J. Org. Chem. 7/2005)
Authors: Bazzini Cristina , Brovelli Sergio , Caronna Tullio , Gambarotti Cristian , Giannone Matteo , Macchi Piero , Meinardi Francesco , Mele Andrea , Panzeri Walter , Recupero Francesco , Sironi Angelo , Tubino Riccardo 
Published: April 2005

AbstractThe cover picture shows the structure of 5‐aza[5]helicene (top) and the crystal packing (single enatiomers, bottom). This is one of the aza[5]helicenes reported in the paper that were synthesized by photochemical ring closure of suitable ethenyl derivatives. The photophysical properties (very long triplet‐state lifetime) and crystal packing (columnar arrangement) were studied and shown to be dependent on the nitrogen position. These molecules may be suitable for studies on π−π interactions and complexation with metal ions. The extremely long triplet lifetime that was observed (in the range of seconds) makes these molecules promising candidates for practical applications in photo‐ and optoelectronics. Details are discussed in the article by T. Caronna et al. on p. 1247 ff.
Polyimide Electrolyte Membranes Having Fluorenyl and Sulfopropoxy Groups for High Temperature PEFCs
Authors: Zhou H. , Miyatake K. , Watanabe M. 
Published: April 2005

AbstractA series of novel polyimide electrolyte copolymers (SPPI‐X) containing fluorenyl and sulfopropoxy groups were synthesized. The copolymer composition (X: molar percentage of the fluorenyl groups) was set from 0–60 mol% so that the ion exchange capacity of the electrolyte membrane ranged from 1.3 to 2.9 meq g–1. Tough and flexible membranes, with the typical polyimide brown colour, were obtained by casting from the polymer solution. The SPPI membranes are thermally stable up to 220 °C without glass transition, melting, and decomposition under a dry nitrogen atmosphere. Sulfopropoxy groups are effective at improving oxidative stability in Fenton's reagent since the main polymer chains are separated from sulfonic acid groups and are less susceptible to hydrophilic attack by the oxidative radical species. A high mechanical strength, with 53 MPa of the maximum stress at break and 15% of strain, was confirmed for SPPI‐30 membrane. The proton conductivity of the SPPI membranes was higher than 0.1 S cm–1 at temperatures from 40 to 120 °C. The long term proton conductivity stability (ca. 1,000 h) was also confirmed at 120 °C, to prove the possible availability of the membrane materials for high temperature PEFC applications.
Plasma‐Polymerised Proton Conductive Membranes for a Miniaturised PEMFC
Authors: Mahdjoub H. , Roualdès S. , Sistat P. , Pradeilles N. , Durand J. , Pourcelly G. 
Published: April 2005

AbstractThin films, containing fluorocarbons and sulphonic acid groups, were prepared by plasma polymerisation of 1,3‐butadiene/CF3SO3H and styrene/CF3SO3H mixtures using two different types of plasma discharges. The morphology, density, and chemical composition of the synthesised plasma polymers were examined by SEM, small‐angle X‐ray reflectometry, and FTIR and XPS analyses, respectively. Proton conductivity was measured with electrochemical impedance spectroscopy. The prepared films are relatively uniform and free from defects. Plasma materials exhibiting higher sulphonic acid group contents and lower densities are those formed, from the styrene/CF3SO3H mixture, in the after glow discharge configuration; which proves that the kind of discharge and the nature of the monomer mixture have a large influence on the microstructure of plasma materials. Consequently, plasma films, prepared in the after glow discharge from the styrene/CF3SO3H mixture, show proton conductivities (up to 9.8 × 10–2 mS cm–1) about one order of magnitude higher than films prepared in the glow discharge (up to 2.2 × 10–3 mS cm–1 and 2.5 × 10–3 mS cm–1 for films prepared from 1,3‐butadiene/CF3SO3H and styrene/CF3SO3H mixtures, respectively). When compared to the commercially available Nafion®, the reference electrolyte polymer in the PEMFC, our most competitive plasma polymers are intrinsically 100 times less conductive. Nevertheless, due to their thinness (about 1 μm), these plasma films show specific resistances (about 1.0 Ω cm2), which are lower than that of the Nafion® membrane (1.9 Ω cm2 specific resistance). This explains their potential significance as polymer electrolyte membranes in a miniaturised PEMFC.
New Preparation Methods for Composite Membranes for Medium Temperature Fuel Cells Based on Precursor Solutions of Insoluble Inorganic Compounds
Authors: Alberti G. , Casciola M. , Pica M. , Tarpanelli T. , Sganappa M. 
Published: April 2005

AbstractCurrent PEMFCs, using perfluorinated membranes, can only operate at temperatures no higher than 70–80 °C, since their performance is dramatically reduced at higher temperatures. Encouraging results, for avoiding the reduction in performance, can be obtained by filling Nafion® membranes with inorganic nano‐particles (composite membranes) and/or by adding inorganic nano‐particles at the membrane/electrode interfaces. However, the efficient insertion of nano‐particles, other than metal oxides, inside a polymeric matrix is often very complicated or not possible. Therefore, it was of interest to find simpler methods for the insertion. In this paper, the preparation of organic precursor solutions of the insoluble compound Zr(O3P‐OH)(O3P‐C6H4SO3H), a proton conductor exhibiting very high conductivity (10–1 S cm–1 at 100 °C and 90 %RH) is reported. It was found that these precursor solutions are more stable the higher the Kb of the solvent and the lower the temperature. Precursor solutions, stable for many days at room temperature, were found by using proton acceptor solvents, such as alkanols, N,N‐dimethyl formamide (DMF), and N‐methyl pyrrolidone (NMP). The particularity of these solutions is that insoluble phosphonate particles are formed when the solvent is evaporated. They are therefore very suitable for filling porous membranes, for the preparation of composite proton conducting membranes, and for the preparation of composite electrodes. Some examples of preparation and use are reported and discussed.
Modelling and Analysis of Electro‐chemical, Thermal, and Reactant Flow Dynamics for a PEM Fuel Cell System
Authors: Khan M. J. , Iqbal M. T. 
Published: April 2005

AbstractIn this paper an approach for the dynamic modelling of polymer electrolyte membrane fuel cells is presented. A mathematical formulation based on empirical equations is discussed and several features, exhibiting dynamic phenomena, are investigated. A generalized steady state fuel cell model is extended for the development of a method for dynamic electrochemical analysis. Energy balance and reactant flow dynamics are also explained through physical and empirical relationships. A well‐researched system (Ballard MK5‐E stack based PGS‐105B system) is considered in order to understand the operation of a practical fuel cell unit. Matlab‐SIMULINKTMhas been used in simulating the models. The proposed method appears to be relatively simple and consequently requires less computation time. Simulation results are compared with available experimental findings and a good match has been observed.