bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of a NifS-Like Chloroplast Protein from Arabidopsis. Implications for Its Role in Sulfur and Selenium Metabolism
Authors: Pilon-Smits Elizabeth A.H. , Garifullina Gulnara F. , Abdel-Ghany Salah , Kato Shin-Ichiro , Mihara Hisaaki , Hale Kerry L. , Burkhead Jason L. , Esaki Nobuyoshi , Kurihara Tatsuo , Pilon Marinus 
Published: December 2002

Abstract
NifS-like proteins catalyze the formation of elemental sulfur (S) and alanine from cysteine (Cys) or of elemental selenium (Se) and alanine from seleno-Cys. Cys desulfurase activity is required to produce the S of iron (Fe)-S clusters, whereas seleno-Cys lyase activity is needed for the incorporation of Se in selenoproteins. In plants, the chloroplast is the location of (seleno) Cys formation and a location of Fe-S cluster formation. The goal of these studies was to identify and characterize chloroplast NifS-like proteins. Using seleno-Cys as a substrate, it was found that 25% to 30% of the NifS activity in green tissue in Arabidopsis is present in chloroplasts. A cDNA encoding a putative chloroplast NifS-like protein, AtCpNifS, was cloned, and its chloroplast localization was confirmed using immunoblot analysis and in vitro import. AtCpNIFS is expressed in all major tissue types. The protein was expressed in Escherichia coli and purified. The enzyme contains a pyridoxal 5′ phosphate cofactor and is a dimer. It is a type II NifS-like protein, more similar to bacterial seleno-Cys lyases than to Cys desulfurases. The enzyme is active on both seleno-Cys and Cys but has a much higher activity toward the Se substrate. The possible role of AtCpNifS in plastidic Fe-S cluster formation or in Se metabolism is discussed.
Early identification of individuals at risk for antisocial personality disorder
Authors: Hill Jonathan 
Published: December 2002

BackgroundAntisocial personality disorder is usually preceded by serious and persistent conduct problems starting in early childhood, and so there is little difficulty in identifying an at-risk group.AimsTo address six key areas concerning the relationship between early conduct problems and antisocial personality disorder.MethodReview of recent research into early identification of and intervention in child conduct problems, following up to possible adult antisocial behaviour.ResultsConduct problems are predictive of antisocial personality disorder independently of the associated adverse family and social factors. Prediction could be aided through identification of subtypes of conduct problems. There is limited evidence on which children have problems that are likely to persist and which will improve; children who desist from early conduct problems and those with onset in adolescence are also vulnerable as adults.ConclusionsThe predictive power of the childhood precursors of antisocial personality disorder provides ample justification for early intervention. Greater understanding of subgroups within the broad category of antisocial children and adults should assist with devising and targeting interventions.
Problems encountered when testing for LSD in a regional medium secure unit
Authors: Acosta-Armas A. J. 
Published: December 2002

Aims and MethodBetween 1998 and 2000, a surprisingly high number of positive results was noticed in our regional medium secure unit when testing for D-lysergic acid diethylamide (LSD). This led to an investigation of possible factors involved. It was felt that the testing protocol, particularly the use of a single, non-isotopic homogeneous immunoassay without routine further confirmatory testing, was largely to blame for what seemed to be a high incidence of false positives. On two different occasions, samples from each patient were sent, on the same day, to two different laboratories. At the first laboratory, only one test method was used and at the second one test plus two confirmatory tests were carried out.ResultsOut of a total of 23 patients tested on two separate occasions, the first laboratory gave three positive results the first time and three positive results the second, while the second laboratory gave only one positive result on the second occasion that samples were sent and none on the first. This reinforces the belief that, without adequate confirmatory analysis, many psychiatric and non-psychiatric prescribed drugs can give false positives.Clinical ImplicationsPositive LSD results should be confirmed by at least one, preferably chromatographic, alternative method. A protocol for testing and reporting LSD in psychiatric patients should be considered in order to minimise the risk of obtaining false-positive results which have negative clinical, legal and psychological repercussions.
Acute mental health admissions in inner London: changes in patient characteristics and clinical admission thresholds between 1988 and 1998
Authors: Fitzpatrick N. K. , Thompson C. J. , Hemingway H. , Barnes T. R. E. , Higgitt A. , Molloy C. , Hargreaves S. 
Published: December 2002

Aims and MethodWe undertook a retrospective case-note review of three cohorts of mental health admissions to determine the extent to which patient and service characteristics changed between 1988 and 1998. Changes in clinical admission thresholds were investigated by a psychiatrists' review of handwritten medical admission assessments.ResultsPatients admitted in 1998 were demographically less stable and clinically more complex than those admitted 10 years earlier. Clinical admission thresholds remained consistent.Clinical ImplicationsOur findings suggest that the perceived increase in pressure on psychiatric services over this period was a response to a change in population need. This study highlights important questions about the clinical decision-making process leading to use of alternatives to admission and the appropriateness of acute admissions.
Perfluorocyclobutane‐Based Arylamine Hole‐Transporting Materials for Organic and Polymer Light‐Emitting Diodes
Authors: Jiang X.Z. , Liu S. , Liu M.S. , Herguth P. , Jen A.K.‐Y. , Fong H. , Sarikaya M. 
Published: December 2002

AbstractA series of in‐situ thermally polymerizable hole‐transporting materials based on the triarylamine‐containing perfluorocyclobutanes (PFCBs) have been developed and characterized. Electrochemical studies reveal that the energy level of the highest occupied molecular orbital (HOMO) for these materials is between –5.1 and –5.3 eV, which is a good match for the work function of indium tin oxide (ITO), a commonly used anode for organic and polymeric light‐emitting diodes. UV‐vis absorption, photo‐ and electro‐luminescence spectral studies indicate that aggregates are formed during the thermal polymerization. The PFCB‐based materials are very robust after polymerization, which enables the fabrication of multilayer polymer light‐emitting diodes. Highly efficient organic and polymer LEDs are demonstrated using these materials as the hole‐transporting layer, illustrating the superb performance of the PFCB‐based polymers.
A Novel Family of Boron‐Containing Hole‐Blocking Amorphous Molecular Materials for Blue‐ and Blue–Violet‐Emitting Organic Electroluminescent Devices
Authors: Kinoshita M. , Kita H. , Shirota Y. 
Published: December 2002

AbstractA novel family of amorphous molecular materials that function as hole blockers in organic electroluminescent (EL) devices, tris(2,3,5,6‐tetramethylphenyl)borane (TPhB), tris(2,3,5,6‐tetramethylbiphenyl‐4‐yl)borane (TBPhB), tris(2,3,5,6‐tetramethyl‐1,1′;4′,1″‐terphenyl‐4‐yl)borane (TTPhB), and tris[4‐(1,1′;3′,1″‐terphenyl‐5′‐yl)‐2,3,5,6‐tetramethylphenyl]borane (TTPhPhB), have been designed and synthesized. They readily form stable amorphous glasses with high glass‐transition temperatures, and are characterized by reversible cathodic reduction and relatively large HOMO–LUMO energy gaps. High‐performance blue‐ and blue–violet‐emitting organic EL devices have been developed using TBPhB, TTPhB, and TTPhPhB as hole blockers and N,N′‐di(1‐naphthyl)‐N,N′‐diphenyl[1,1′‐biphenyl]‐4,4′‐diamine, tri(p‐terphenyl‐4‐yl)amine, and N,N′‐bis(3‐methylphenyl)‐N,N′‐diphenyl‐[1,1′‐biphenyl]‐4,4′‐diamine as emitters.
Soft Contact Deposition onto Molecularly Modified GaAs. Thin Metal Film Flotation: Principles and Electrical Effects
Authors: Vilan A. , Cahen D. 
Published: December 2002

Abstract We describe and analyze a process to position a ∼ 1 nm thick molecular layer between two solid surfaces without damage to the molecules. The method is used to deposit a metal film in a soft, gentle manner on a semiconductor, yielding functional semiconductor/molecule/metal junctions. It is a combination of the lift‐off procedure, known from, for example, lithography, and the bonding process, known from, for example, wafer bonding. The combined method may find application also outside the area described here. We point out its major difficulties as well as solutions to overcome them. For this we rely on concepts from the physics of liquid and solid surfaces and interfaces. Conditions are found, in terms of choice of solvents, under which the method will be effective. The efficacy of floatation as a soft contacting procedure is demonstrated by the preparation of Au and Al contacts on GaAs single crystal surfaces, modified by a self‐assembled monolayer of small organic molecules. The resulting electrical properties of the contacts depend crucially on how the molecular interface with the contacting metal is formed. This type of wet contacting procedure to make dry devices may be advantageous especially if biomolecules are used.
Synthesis, Structural Evaluation, and Estrogen Receptor Interaction of 4, 5‐Bis(4‐hydroxyphenyl)imidazoles
Authors: Gust Ronald , Keilitz Roland , Schmidt Kathrin , von Rauch Moriz 
Published: December 2002

Abstract4, 5‐Bis(4‐hydroxyphenyl)imidazoles with 2, 2′‐H (1), 2, 2′‐F (2), 2, 2′‐Cl (3), and 2, 2′6‐Cl (4) substituents in the aromatic rings were synthesized by oxidation of the respective methoxy‐substituted (R, S)/(S, R)‐4, 5‐diaryl‐2‐imidazolines with MnO2 and subsequent ether cleavage with BBr3. N‐alkylation of 1 and 3 with ethyl iodide yielded the compounds 5 and 6. The imidazoles were characterized by NMR spectroscopy and tested for estrogen receptor binding in a competition experiment with [3H]estradiol using calf uterine cytosol. Gene activation was verified in a luciferase assay using estrogen receptor positive MCF‐7‐2a cells stably transfected with the plasmid EREwtcluc. All halide substituted imidazoles competed with estradiol for the binding site at the estrogen receptor. The N‐ethyl derivative 6 showed the highest relative binding affinity of 1.26 %. Treatment of MCF‐7‐2a cells, however, did not lead to gene activation. The relative activation of 6 amounted only to 10 % at 1μM compared to E2 (100 %).
[60]Fullerene: A Versatile Photoactive Core for Dendrimer Chemistry
Authors: Nierengarten Jean‐François , Armaroli Nicola , Accorsi Gianluca , Rio Yannick , Eckert Jean‐François 
Published: December 2002

AbstractOwing to their special photophysical properties, fullerene derivatives are good candidates to demonstrate dendritic effects. In particular, the triplet lifetimes of a C60 core can be used to evaluate its degree of isolation from external contacts. On the other hand, the fullerene core can act as a terminal energy receptor in dendrimer‐based light‐harvesting systems. When a fullerodendrimer is further functionalized with a suitable electron donor, it may exhibit the essential features of a multicomponent artificial photosynthetic system in which photoinduced energy transfer from the antenna to the C60 core is followed by electron transfer.
Modular Synthesis of Heparin Oligosaccharides
Authors: Orgueira Hernán A. , Bartolozzi Alessandra , Schell Peter , Litjens Remy E. J. N. , Palmacci Emma R. , Seeberger Peter H. 
Published: December 2002

AbstractA general, modular strategy for the first completely stereoselective synthesis of defined heparin oligosaccharides is described. Six monosaccharide building blocks (four differentially protected glucosamines, one glucuronic and one iduronic acid) were utilized to prepare di‐ and trisaccharide modules in a fully selective fashion. Installation of the α‐glucosamine linkage was controlled by placing a conformational constraint on the uronic acid glycosyl acceptors thereby establishing a new concept for stereochemical control. Combination of disaccharide modules to form trans‐uronic acid linkages was completely selective by virtue of C2 participating groups. Coupling reactions between disaccharide modules exhibited sequence dependence. While the union of many glucosamine uronic acid disaccharide modules did not meet any problems, certain sequences proved not accessible. Elaboration of glucosamine uronic acid disaccharide building blocks to trisaccharide modules by addition of either one additional glucosamine or uronic acid allowed for stereoselective access to oligosaccharides as demonstrated on the example of a hexasaccharide resembling the ATIII‐binding sequence. Final deprotection and sulfation yielded the fully synthetic heparin oligosaccharides.
Formation and Chemical Reactivities of a New Type of Double‐Butterfly [{Fe2(μ‐CO)(CO)6}2(μ‐SZS‐μ)]2−: Synthetic and Structural Studies on Novel Linear and Macrocyclic Butterfly Fe/E (E=S, Se) Cluster Complexes
Authors: Song Li‐Cheng , Fan Hong‐Tao , Hu Qing‐Mei , Yang Zhi‐Yong , Sun Yi , Gong Feng‐Hua 
Published: December 2002

AbstractA new type of double‐butterfly [{Fe2(μ‐CO)(CO)6}2(μ‐SZS‐μ)]2− (3), a dianion that has two μ‐CO ligands, has been synthesized from dithiol HSZSH (Z=(CH2)4, CH2(CH2OCH2)1–3CH2), [Fe3(CO)12], and Et3N in a molar ratio of 1:2:2 at room temperature. Interestingly, the in situ reactions of dianions 3 with various electrophiles affords a series of novel linear and macrocyclic butterfly Fe/E (E=S, Se) cluster complexes. For instance, while reactions of 3 with PhC(O)Cl and Ph2PCl give linear clusters [{Fe2(μ‐PhCO)(CO)6}2(μ‐SZS‐μ)] (4 a,b: Z=CH2(CH2OCH2)2,3CH2) and [{Fe2(μ‐Ph2P)(CO)6}2(μ‐SZS‐μ)] (5 a,b: Z=CH2(CH2OCH2)2,3CH2), reactions with CS2 followed by treatment with monohalides RX or dihalides XYX give both linear clusters [{Fe2(μ‐RCS2)(CO)6}2(μ‐SZS‐μ)] (6 a–e: Z=CH2(CH2OCH2)1,2CH2; R=Me, PhCH2, FeCp(CO)2) and macrocyclic clusters [{Fe2(CO)6}2(μ‐SZS‐μ)(μ‐CS2YCS2‐μ)] (7 a–e: Z=(CH2)4, CH2(CH2OCH2)1–3CH2; Y=(CH2)2–4, 1,3,5‐Me(CH2)2C6H3, 1,4‐(CH2)2C6H4). In addition, reactions of dianions 3 with [Fe2(μ‐S2)(CO)6] followed by treatment with RX or XYX give linear clusters [{[Fe2(CO)6]2(μ‐RS)(μ4‐S)}2(μ‐SZS‐μ)] (8 a–c: Z=CH2(CH2OCH2)1,2CH2; R=Me, PhCH2) and macrocyclic clusters [{[Fe2(CO)6]2(μ4‐S)}2(μ‐SYS‐μ)(μ‐SZS‐μ)] (9 a,b: Z=CH2(CH2OCH2)2,3CH2; Y=(CH2)4), and reactions with SeCl2 afford macrocycles [{Fe2(CO)6}2(μ4‐Se)(μ‐SZS‐μ)] (10 d: Z=CH2(CH2OCH2)3CH2) and [{[Fe2(CO)6]2(μ4‐Se)}2(μ‐SZS‐μ)2] (11 a–d: Z=(CH2)4, CH2(CH2OCH2)1–3CH2). Production pathways have been suggested; these involve initial nucleophilic attacks by the Fe‐centered dianions 3 at the corresponding electrophiles. All the products are new and have been characterized by combustion analysis and spectroscopy, and by X‐ray diffraction techniques for 6 c, 7 d, 9 b, 10 d, and 11 c in particular. X‐ray diffraction analyses revealed that the double‐butterfly cluster core Fe4S2Se in 10 d is severely distorted in comparison to that in 11 c. In view of the Z chains in 10 a–c being shorter than the chain in 10 d, the double cluster core Fe4S2Se in 10 a–c would be expected to be even more severely distorted, a possible reason for why 10 a–c could not be formed.
Metal Catalysis inside Polymer Frameworks: Evaluation of Catalyst Stability and Reusability
Authors: Králik Milan , Kratky Vieroslav , De Rosso Mirco , Tonelli Massimo , Lora Silvano , Corain Benedetto 
Published: December 2002

AbstractThe polymer framework of a resin‐based catalyst built up with Pd nanoclusters (ca. 3 nm) dispersed inside the nanoporous domains of a thermally stable gel‐type polyacrylic resin exhibits a good chemical stability under 5 bar H2 at 40 °C for reasonable contact times. Chemical and physico‐chemical integrity of the polymer framework are checked with a variety of instrumental analytical methods. Catalyst reusability turns out to be quite good.
Electron‐Transfer Chemistry of the Iron–Molybdenum Cofactor of Nitrogenase: Delocalized and Localized Reduced States of FeMoco which Allow Binding of Carbon Monoxide to Iron and Molybdenum
Authors: Pickett Christopher J. , Vincent Kylie A. , Ibrahim Saad K. , Gormal Carol A. , Smith Barry E. , Best Stephen P. 
Published: December 2002

AbstractThe electron‐transfer chemistry of the isolated iron–molybdenum cofactor of nitrogenase (FeMoco) has been studied by electrochemical and spectroelectrochemical methods. Two interconverting forms of the cofactor arise from a redox‐linked ligand isomerism at the terminal iron atom; this is attributed to rotamerism of an anionic N‐methyl formamide ligand bound at this site. FeMoco in its EPR‐silent oxidised state is shown to undergo three successive one‐electron transfer steps. We argue that the first and second redox processes are associated with electron‐transfer delocalised over the iron–sulfur core of the cofactor, whilst the third irreversible process is localised on molybdenum. This is strongly reinforced by spectroelectrochemical studies under 12CO and 13CO which reveal two independent carbon monoxide binding sites that are specifically associated with the second (iron core) and third (molybdenum) electron‐transfer processes and which give rise to terminal ν(12CO) bands at 1885 and 1920 cm−1 respectively. Moreover, in parallel with earlier studies on the enzyme system, it is shown that at low CO concentration, carbon monoxide binds to the cofactor in bridging modes, with ν(CO) bands at 1835 and 1808 cm−1 that are interconverted by single‐electron transfer. Importantly we show that the contentious overall 2e difference in the assignment of the metal oxidation levels in the resting state of the enzyme‐bound cofactor, arising from analysis of 57Fe ENDOR and Mössbauer data, can be resolved in the light of the electron‐transfer chemistry of the isolated cofactor described herein.
The Final Steps of the Oppolzer Cyclization: Mechanism of the Insertion of Alkenes into Allylpalladium(II) Complexes
Authors: Cárdenas Diego J. , Alcamí Manuel , Cossío Fernando , Méndez María , Echavarren Antonio M. 
Published: December 2002

AbstractWe report here the results of a computational study on the the mechanism of the Oppolzer cyclization. These results lead us to conclude that the insertion of olefins in Pd–allyl complexes probably takes place directly from theη3‐allyl species. The presence of a phosphane ligand in the reagents plays the role of enhancing the electron density on the Pd atom; this makes the alkene moiety more reactive towards insertion by back‐donation from the metal. The results also indicate that the configuration of the new stereogenic centers is fixed in the insertion of the alkene into the (η3‐allyl)palladium species.
Effects of controlled pH on organic and inorganic composition in haemolymph, epidermal tissue and cuticle of mud crab Scylla serrata
Authors: Pratoomchat Boonyarath , Sawangwong Pichan , Machado Jorge 
Published: December 2002

AbstractAnalysis of organic and inorganic compounds in plasma, epidermal tissue and cuticle were accomplished in the intermolt (C3 stage) of crab Scylla serrata incubated in different pH media. Significant changes with similar trends for protein, carbohydrates, glycosaminoglycans (GAG), sulphur, calcium, magnesium, potassium, phosphorus and copper in the plasma suggested higher dissolution in an acidic medium while the deposition increased in alkaline medium. Similar decreases in protein, carbohydrate and GAG in the epidermal compartment were observed from pH 4 to pH 12. However, significantly higher contents of sodium, chloride, potassium, phosphorus, magnesium, sulphur and copper were measured at pH 7.5 with a symmetrical decrease profile in both acidic and alkaline media, resulting from synergistic effects in the osmotic regulation. Clear changes in calcium concentrations were observed with a sharp increase from lower contents at pH 7.5 to higher at pH 12. In the cuticle, the acidic condition induced a significant dissolution of HCl‐protein, GAG, calcium and magnesium contents. On the other hand, the alkaline condition induced a significant decrease in carbohydrate, calcium, chloride, sulphur and potassium. A reduction trend is seen for NaOH and H2O‐protein contents in the cuticle. These observations suggest that GAG and HCl‐protein might constitute the most soluble fraction with high affinity for calcium binding and easily removed in acidic conditions. Additionally, it is possible to speculate that the carbohydrates associated with the NaOH and H2O‐proteins may form an interface between the soluble matrix fraction and the chitin framework. Sulphur groups seem to present a strong linkage role in this interface fraction, maybe only broken by a specific enzyme in extreme alkaline conditions with subsequent release of significant calcium from the shell. J. Exp. Zool.295A:47–56, 2003. © 2003 Wiley‐Liss, Inc.
Cyclin A2 Is differentially expressed during oocyte maturation between gynogenetic silver crucian carp and gonochoristic color crucian carp
Authors: Xie Jing , Wen Jian‐Jun , Yang Zhong‐An , Wang Hong‐Ying , Gui Jian‐Fang 
Published: December 2002

AbstractSilver crucian carp (Carassius auratus gibelio) is a unique gynogenetic fish. Because of its specific genetic background and reproduction mode, it is an intriguing model system for understanding regulatory mechanism of oocyte maturation division. It keeps its chromosomal integrity by inhibiting the first meiotic division (no extrusion of the first pole body). The spindle behavior during oocyte maturation is significantly different from that in gonochoristic fish. The chromosomes are first arranged in a tripolar spindle, and then they turn around and are reunited mutually to form a normal bipolar spindle. A new member of the fish A‐type cyclin gene, cyclin A2, has been isolated by suppression of subtractive hybridization on the basis of its differential transcription in fully‐grown oocytes between the gynogenetic silver crucian carp and gonochoristic color crucian carp. There are 18 differing amino acids in the total 428 residues of cyclin A2 between the two forms of crucian carps. In addition, cDNAs of cyclin Al and cyclin B have also been cloned from them. Thus two members of A‐type cyclins, cyclin Al and cyclin A2, are demonstrated to exist in fish, just as in frog, humans, and mouse. Northern blotting reveals that cyclin A2 mRNA is more than 20‐fold and cyclin A1 mRNA is about 2‐fold in fully grown oocytes of gynogenetic silver crucian carp compared to gonochoristic color crucian carp. However, cyclin B does not show such a difference between them. Western blot analysis also shows that the cyclin A2 protein stockpiled in fully grown oocytes of gynogenetic crucian carp is much more abundant than in gonochoristic crucian carp. Moreover, two different cyclin A2 expression patterns during oocyte maturation have been revealed in the two closely related crucian carps. For color crucian carp, cyclin A2 protein is translated only after hormone stimulation. For silver crucian carp, cyclin A2 protein can be detected throughout the process of maturation division. The different expression of cyclin A2 may be a clue to understanding the special maturation division of gynogenetic silver crucian carp. J. Exp. Zool. 295A:1–16, 2003. © 2003 Wiley‐Liss, Inc.