bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomimetic Ion‐binding Monolayers on Gold and Their Characterization by AC‐Impedance Spectroscopy
Authors: Gafni Yael , Weizman Haim , Libman Jacqueline , Shanzer Abraham , Rubinstein Israel
Published: September 2007

Novel ion‐binding monolayers on gold surfaces are presented where the molecular design is based upon the natural ion binder ferrichrome. The new ion binders possess hydroxamate coordinating groups arranged in C2 symmetry (bishydroxamate binder, BHB) or C3 symmetry (trishydroxamate binder, THB), and a separate dialkyl sulfide moiety, which serves as an anchor to the gold substrate. The separation between the ion‐binding cavity and the attachment site to the gold allows each parameter to be controlled separately, namely, cavity size, its symmetry and external envelope, as well as the functional group used for immobilization. The monolayers were characterized with respect to ellipsometric thickness, wettability (advancing and receding contact angles (CAs) for water), and surface coverage; the latter is determined by metal underpotential deposition (UPD). It is shown that the introduction of hydrophobic side chains (i‐butyl) improves the CAs, thickness, and surface coverage of the monolayers. A detailed analysis of the alternating‐current (AC) impedance spectra is presented for THB monolayers on gold electrodes, where the impedance data are fitted to an equivalent circuit model. It is shown that the AC response in a wide frequency range can be used to probe ion binding and release in monolayer systems on electrodes.
Formation of Bridging Nitride Versus Terminal Oxovanadium Promoted by a Vanadium(II) Macrocyclic Complex
Authors: Jubb Jayne , Scoles Ludmila , Jenkins Hilary , Gambarotta Sandro
Published: September 2007

The reaction of [VCl2(tmeda)2] with the tetralithium salt of octaethylporphyrinogen (oepg)[Li(thf)]4 initially yielded a monomeric VII complex [(oepg)‐VLi4Cl2(thf)4] (1). Treatment of this species with tetramethylethylenediamine afforded a mixture from which [(oepg)‐V(thf)2][Li(tmeda)2].0.5 toluene (2 a) (or 2 b when ethyl is replaced by nPr) and the unprecedented nitrido‐bridged dimeric species [{oepg)V}2(μ‐N)(μ‐Li) 4]‐[Li(tmeda)2] (3) were isolated and characterized. The bridging nitrogen atom probably originated from the cleavage of dinitrogen, since the same reaction carried out under exclusion of N2 gave [(oepg)VO]‐[Li(tmeda)]2 (4), where the oxo atom probably originated from deoxygenation of THF. The connectivity of 1, 2 b, 3, and 4 was demonstrated by X‐ray analysis.
Structure and Conductivity of an Electrocrystallized Ruthenium [1,8]Binaphthyridine Complex
Authors: Pérez‐Cordero Eduardo , Brady Nancy , Echegoyen Luis , Thummel Randolph , Hung Chi‐Ying , Bott Simon G.
Published: September 2007

For the first time, the crystal structure of a RuII binaphthyridine complex and that of its corresponding oneelectron reduced product are reported. Reductive electrocrystallization of [Ru‐(binap‐2)3](PF6)2 (1, where binap‐2 = 3,3′‐dimethylene ‐2,2′ ‐ bi [1, 8] naphthyridine) from an acetonitrile solution resulted in the formation of dark blue crystals of the one‐electron reduction product, [Ru‐(binap‐2)3](PF6) (2) having one fewer PF−6 per formula unit. X‐ray analysis reveals that the reduced complex retains the three‐ligand d6 coordination around the central RuII. Based on electrostatic considerations and the positions of the PF−6 anions in the lattice, the added electron appears to be delocalized over two nearly equivalent binap‐2 ligands in 2, in marked contrast to monoreduced and electrocrystallized [Na ⊂ (trisbipyridyl cryptand)]0, in which the electron is localized on only one of the bipyridyl subunits. However, based on the available data, alternative interpretations are possible. The crystal packing diagram of 2 shows several intermolecular π–π interactions, with 12 of these being shorter than 3.5 Å. In contrast, there are no intermolecular distances shorter than 3.5 Å in the crystals of 1. Two‐probe electrical conductivity measurements under anaerobic conditions indicate that the crystals of 2 behave as semiconductors with a band gap of 0.53 eV, while those of the unreduced compound are insulating. This represents the first molecular semiconducting material with the potential for bidimensional behavior of its kind.
Enantioselective Synthesis of Highly Functionalized 4‐Piperidones by the Asymmetric Imino‐Diels–Alder Reaction of Chiral 2‐Amino‐1,3‐Butadienes
Authors: Barluenga José , Aznar Fernando , Ribas Cristina , Valdés Carlos , Fernández Monica , Cabal María‐Paz , Trujillo Jesús
Published: September 2007

Chiral 2‐amino‐1,3‐butadienes 1 derived from commercially available (S)‐2‐methoxymethylpyrrolidine react with aromatic N‐trimethylsilylaldimines and N‐phenylaldimines in the presence of ZnCl2 to give, after the reaction workup, 4‐piperidones 4 and 6, respectively, with moderate to very high enantiomeric excesses. In addition, the absolute configurations of derivatives of 4 a and 4 g were determined by circular dichroism and NMR spectroscopy on the Mosher ester, respectively.
Total Synthesis of Swinholide A, Preswinholide A, and Hemiswinholide A
Authors: Nicolaou K. C. , Patron A. P. , Ajito K. , Richter P. K. , Khatuya H. , Bertinato P. , Miller R. A. , Tomaszewski M. J.
Published: September 2007

The total synthesis of synthesis of swinholide A (1) has been accomplished via key intermediate aldehyde 12 (Fig. 3), whose construction started from L‐rhamnose (18), epoxide 21, and phenylsulfone orthoester 22, and proceeded through an Enders asymmetric alkylation (16 + 17 → 15), a Ghosez cyclization (21 + 22 → 20), and a Corey‐Sharpless coupling reaction (13 + 14 → 12). Elaboration of compound 12 along slightly different pathways culminated in the synthesis of carboxylic acid 10 and hydroxy compound 11, whose union by an esterification reaction, followed by ring closure of the subsequently derived hydroxy acid under Yamaguchi conditions, led to swinholide A (1) upon deprotection. The chemistry developed also allowed the total synthesis of preswinholide A methyl ester (7), preswinholide A (8), and hemiswinholide A (78).
Oxypyriporphyrin, the First Fully Aromatic Porphyrinoid Macrocycle with a Pyridine Subunit
Authors: Lash Timothy D. , Chaney Sun T.
Published: September 2007

The synthesis of the first example of an aromatic pyridine‐containing porphyrinoid 10 has been accomplished in excellent yields by the acid‐catalyzed “3 + 1” condensation of 3‐hydroxy‐pyridinedicarboxaldehyde (8) with tri‐pyrrane 9. The key intermediate 8 was obtained by the selenium dioxide oxidation of the known biscarbinol 7. The aromaticity of “oxypyriporphyrin” 10 has been confirmed by MS, NMR, IR, and UV/Vis spectroscopy. This system afforded a monocation in 0.2% TFA‐chloroform, and a dication was observed in 2% TFA‐chloroform; these species also retained macrocyclic aromaticity. Oxypyriporphyrin readily formed the corresponding metal chelates 14a‐c by reaction with zinc, copper(II), or nickel(II) acetate, and this observation suggests that there are extensive possibilities for the use of 10 in coordination chemistry. Oxypyriporphyrin and the related semiquinone system oxybenziporphyrin represent the first two members of a new class of aromatic porphyrinoids.
Oxidative Addition of Aryl Halides to Transient Anionic à‐Aryl–Palladium(0) Intermediates—Application to Palladium‐Catalyzed Reductive Coupling of Aryl Halides
Authors: Amatore Christian , Carré Emmanuelle , Jutand Anny , Tanaka Hideo , Ren Qinghua , Torii Sigeru
Published: September 2007

The rates and mechanism of the reactions of a series of aryl‐ligated, anionic palladium(0) complexes Ar‐Pd0‐(PPh3)‐2 with para‐substituted iodobenzenes were investigated by means of transient electrochemistry. The reaction was found to be first order in each reactant and to proceed similarly to oxidative addition of aryl halides to the halide‐ligated species X‐Pd0(PPh3)‐2, although much faster and less sensitive to electronic factors. Owing to the short lifetime (t1/2 ≈︁ 1 – 5 ms) of the product of this reaction, it could not be characterized in detail. However, based on kinetic results, this transient species is thought to be an anionic pentacoordinated bisarylpalladium(II) complex, which undergoes rapid loss of halide ligand to yield, most probably, a bisarylpalladium(II) neutral species. Based on the study of this reaction and on previously reported results, we propose a mechanism for the palladium‐catalyzed homocoupling of aryl halides consisting of a catalytic cycle initiated by oxidative addition of an aryl halide to a zerovalent tris‐ligated palladium center. Two‐electron reduction of the pentacoordinated arylpalladium(II) anionic species thus formed gives a tris‐ligated anionic arylpalladium(0) center, which undergoes oxidative addition with a second aryl halide molecule to eventually lead to a bisaryl‐palladium(II) neutral species. Reductive elimination of a bisaryl molecule from this center closes the catalytic cycle by regenerating the initial zerovalent palladium complex. The application of this sequence to the catalytic heterocoupling of aryl halides is discussed, and it is concluded, on the basis of Hammett correlations, that statistical yields should be observed, in agreement with the results obtained for preparative reactions in DMF.
Structural Motifs of the Dimeric Lewis Glycolipids as Determined by NMR Spectroscopy and Molecular Dynamics Simulations
Authors: Geyer Armin , Hummel Gerd , Eisele Thomas , Reinhardt Stefan , Schmidt Richard R.
Published: September 2007

Several monomeric and dimeric Lewis glycolipids have been investigated by NMR spectroscopy, and structural aspects were modelled by computer. From the pseudo‐C2‐symmetric tetrasaccharide unit that forms the recognition domain of the Lewis Y and Lewis b antigens, a totally C2‐symmetric tetrasaccharide was designed that contains the structural element common to all Lewis antigens. Finally, a model for the presentation of dimeric Lewis antigens at membrane surfaces was derived. The overall shapes of the dimeric Lewis oligosaccharides are defined by the connectivity of the sugar residues within rigid tri‐ and tetrasaccharide building blocks.
Protonation and Alkylation of the Thiolato Donors in [Fe(CO)(“NHS4”)]: Effects on the Structural, Electronic, and Redox Properties of Metal–Sulfur Complexes
Authors: Sellmann Dieter , Becker Thomas , Knoch Falk
Published: September 2007

The effects of protonation and alkylation at the sulfur donors in metal‐sulfur complexes have been investigated by taking the specific example of [Fe(CO)(“NHS4”)] (1). The 18 valence electron (VE) complex 1 consists of a low‐spin FeII center and the dithioether thiolato amine ligand “NHS4”2‐‐ ( = 2,2′‐bis(2‐mercaptophenylthio)diethylamine(2‐)). Complex 1 can be reversibly protonated at the two thiolato donors; this results in an increase in ν(CO) of 35 cm‐1 after the first protonation and 45 cm‐1 after the second. Alkylation of 1 with one or two equivalents of the oxonium salts R3OBF4 (R = Me, Et) yields [Fe(CO)(“NHS4”‐R)]BF4 (R = Me: 4, Et: 5), [Fe(CO)(“NHS4” ‐R2)](BF4)2 (R = Me: 6, Et: 7), and the methyl ethyl derivative [Fe(CO)(“NHS4” ‐Me‐Et)](BF4)2 (8). An increase in ν(CO) of 31–32 cm‐1 is observed for each successive alkylation. Due to the C1 symmetry of 1, complexes 4, 5, and 8 are formed as 1 : 1 mixtures of two diastereomers, whereas 6 and 7 are present as only one stereoisomer. Acidic hydrolysis of 4, 6, and 7 liberates the corresponding ligands [“NHS4” ‐Rn](BF4)n (9–11; n = 1,2), which were isolated as the ammonium tetrafluoroborate salts. The molecular structure of 8a has been elucidated by X‐ray structure analysis. This shows that the Fe–N and Fe–S bonds in the [FeNS4] core do not change after alkylation of the thiolato donors despite the Δν(CO) of ca. 60 cm‐1 between 1 and 8, which indicates a distinct decrease in electron density at the Fe center. This decrease can be rationalized by increased π‐acceptor character of the sulfur donors upon protonation or alkylation. The change in electron density at the [Fe(“NS4”)] core is further corroborated by cyclic voltammetry. For each successive protonation or alkylation of 1, the redox couple potentials shift by 600–800 mV. As a consequence, the diethyl derivative, for example, gives rise to reduced species (19 or 20 VE) which are not observed for 1. The implications of these results for the reduction of N2 within the coordination sphere of the FeMo cofactor of nitrogenases are discussed.
An Unexpected Structural Principle for Crystalline MgBr2·OEt2: Chains of Trigonal Bipyramids
Authors: Ecker Achim , Üffing Christoph , Schnöckel Hansgeorg
Published: September 2007

MgBr2·OEt2 (1), which is commercially available and has been examined by different methods in the past, was obtained in crystalline form as a by‐product of the reaction of amine‐stabilised AlCl solution with mesitylene magnesium bromide. The following unexpected structure was obtained by X‐ray techniques: five‐coordinate magnesium centres form trigonal bipyramids, which are connected by two common bromine atoms into chains. Structural details and especially the relationship with solid MgBr2, MgBr2·(OEt2)2 and MgI2·(OEt2)2 (2) are discussed in order to illuminate the unusual bonding in 1.
Multi‐Mode Switching Based on Dihydroazulene/vinylheptafulvene Photochromism: Synergism of Photochromism and Redox Switching in Heteroaryl‐Functionalized Systems
Authors: Spreitzer Hubert , Daub Jörg
Published: September 2007

The syntheses of the dihydroazulenes (DHAs) DHA‐a‐DHA‐f containing covalently linked heteroaromatic subunits derived from dibenzodioxin, thianthrene, phenoxathiine, N‐methylphenothiazine, N‐methylphenoxazine, and N,N′‐dimethylphenazine groups are described, and their spectroscopic and analytical data are reported. The dihydroazulene/vinylheptafulvene (DHA/VHF) photochromism (photochemical forward and thermal back reaction) depends with high sensitivity on the electronic properties of the functional groups. Whereas the dimethylphenazine derivative DHA‐f is photochemically inactive towards rearrangement, all other DHAs (DHA‐a‐DHA‐e) were found to isomerize to the corresponding vinylheptafulvene forms under irradiation. Cyclic voltammetry revealed that the DHA and the VHP forms have significantly different oxidation and reduction waves. The products of the‐oxidative one‐electron transfer are characterized by UV/Vis/NIR spectroelectrochemistry. Those DHAs having weaker donor substituents (DHA‐a‐DHA‐c) undergo oxidative dimerization whereas DHAs with stronger donating heterocyclic subunits (DHA‐d‐DHA‐f) form stable radical cations.
Molecular Structure, Vibrational Spectrum and Ionization Energy of m‐Dimethoxybenzene
Authors: Huang Jian‐Han , Huang Ke‐Long , Liu Su‐Qin , Luo Qiong
Published: September 2007

The optimized molecular geometries of the three rotamers of m‐dimethoxybenzene in the ground S0 and electronically excited S1 states were predicted by ab initio and density functional theory (DFT) calculations. Their vibrational spectra in the S1 state were studied by one color resonant two photon ionization (1C‐R2PI) method, and their ionization energies were measured by two color resonant two photon ionization (2C‐R2PI) experiment. The optimized molecular geometries showed that the total energy of conformer a was the lowest in the S0 state. Most of the active vibrations assigned from the 1C‐R2PI spectrum were found to be of the in‐plane ring modes. The ioniza‐ tion energies (IE) of conformers a, b and c were determined to be 63521, 64487 and 63755 cm−1, respectively.
Iridium Oxide Film‐Enhanced Impedance Immunosensor for Rapid Detection of Carcinoembyronic Antigen
Authors: Ding Yan‐Jun , Wang Hua , Jiang Jian‐Hui , Shen Guo‐Li , Yu Ru‐Qin
Published: September 2007

A simple, rapid and sensitive impedance immunosensor based on iridium oxide (IrOx) thin film for the detection of carcinoembyronic antigen (CEA) in human sera has been proposed. Gold electrode was electrochemically modified with IrOx thin film and simultaneously functionalized with protein A (PA) to bind anti‐CEA antibodies in an orientated way. It has been found that the antibody loading amount was dependent on the PA concentration and the deposition time of IrOx matrix. Under the optimized experimental conditions, the electron transfer resistances obtained were linearly related to the CEA concentration ranging from 36.2 to 460.0 ng/mL, with a detection limit of 28.0 ng/mL. Analytical results of clinical samples from cancer patients show that the proposed immunoassay is reasonably comparable with the chemiluminescence immunoassay (CLIA), indicating the feasibility of using the proposed method for CEA immunoassay in clinical laboratory.
Two Novel Antibacterial Flavonoids from Myrsine Africana L.
Authors: Kang Lu , Zhou Jian‐Xia , Shen Zheng‐Wu
Published: September 2007

Two novel flavonoids, myrsininone A (1), an isoflavone and myrsininone B (2), a flavanone, with very strong antibacterial activities, were isolated from the stems of Myrsine africana L. Their structures were elucidated by extensive spectroscopic analyses. The antibacterial activities were determined by modified Resazuric MIC methods.
Environmentally Benign Oxidation of Some Organic Sulfides with 34% Hydrogen Peroxide Catalyzed by Simple Heteropolyoxometalates
Authors: Tayebee Reza , Alizadeh Mohammad Hassan
Published: September 2007

An environmentally benign oxygenation protocol was developed for selective oxidation of some types of aromatic and aliphatic sulfides in good to excellent yields utilizing 34% hydrogen peroxide catalyzed by simple heteropolyoxometalates in normal drinking water at room temperature. The catalysts could be recovered and reused for at least seven reaction cycles under the described reaction conditions without considerable loss of reactivity. This procedure introduced a new insight into the use of simple heteropolyanions as recoverable catalysts for the oxidation of organic sulfides by an environmentally acceptable protocol.
Synthesis and Electrospray Ionization Mass Spectra of N‐(1,3, 2‐Dioxaphosphorinan‐2‐ylmethyl)thiophosphoramidates
Authors: Miao Zhi‐Wei , Fu Cui‐Rong , Wang Bin , Cui Zhan‐Wei , Zhang Jian‐Feng , Chen Ru‐Yu
Published: September 2007

N‐(1,3,2‐Dioxaphosphorinan‐2‐ylmethyl)thiophosphoramidates were synthesized and determined by NMR spectra and positive ion electrospray ionization mass spectrometry (ESI‐MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated. The results show that these characteristic ions in ESI mass spectra are useful in the structural determination of N‐(1,3,2‐dioxaphosphorinan‐2‐ylmethyl)thiophosphoramidates.
Synthesis and Microbial Studies of New Pyridine Derivatives‐III
Authors: Patel N. B. , Agravat S. N.
Published: September 2007

2‐Amino substituted benzothiazole 4a–4l and p‐acetamidobenzenesulfonyl chloride 2 were used to prepare 2‐(p‐aminophenylsulfonamido) substituted benzothiazole 6a–6l using mixture of pyridine and acetic anhydride which formed an electrophilic complex (N‐acetyl pyridinium) to facilitate condensation to give desired product by removal of HCl. 2‐{p‐[(3‐Carboxypyrid‐2‐yl)amino]phenylsulfonamido}benzothiazoles 8a–8l were synthesized from 2‐chloropyridine‐3‐carboxylic acid 7 and 6a–6l in 2‐ethoxy ethanol using Cu‐powder and K2CO3. Acid chlorides 9a–9l were condensed with 2‐hydroxyethyl piperazine 10 and 2,3‐dichloropiperazine 11 for amide derivatives 2‐(p‐((3‐(4‐(2‐hydroxyethyl)piperazin‐1‐ylcarbonyl)pyrid‐2‐yl)amino)phenylsulfonamido)benzothiazoles 12a–12l and 2‐{p‐[3‐(2,3‐dichloropiperazin‐1‐ylcarbonyl)pyrid‐2‐ylamino]phenylsulfonamido}benzothiazoles 13a–13l respectively. The structures of the new compounds have been established on the basis of their chemical analysis and spectral data (IR, 1H NMR and mass). All the compounds have been screened for their antibacterial and antifungal activities.
Theoretical Investigation on the Absorption and Emission Properties of the Three Isomers of Bis(thiocyanato)(2,2′‐bipyridyl)platinum(II)
Authors: Hu Xiao‐Ying , Liu Xiao‐Juan , Feng Ji‐Kang
Published: September 2007

This paper presents a Density Functional or Time Dependent Density Functional (DFT/TDDFT) study of the molecular and electronic structures, optical absorption and emission spectra of three linkage isomers:bis(isothiocyanato‐S)(2,2′‐bipyridyl) platinum(II) ([Pt(SCN)2(bpy)]), (isothiocyanato‐S)(thiocyanato‐N)‐(2,2′‐bipy‐ ridyl) platinum(II) ([Pt(SCN)(NCS)(bpy)]), and bis(thiocyanato‐N)(2,2′)‐bipyridyl)platinum(II) ([Pt(NCS)2(bpy)]), in which different coordination ligands based on the N‐ and S‐coordination of the thiocyanato ligands control the luminescent color. The electronic structures were studied using the B3LYP functional. Optimized geometries were compared to the experimentally observed structures. TDDFT calculation was carried out to investigate the excited singlet and triplet states. Calculations have been performed both in vacuo and in solvents, using a polarized continuum model (PCM) to account for solute‐solvent interactions. Inclusion of the solvent led to a significant energy change, and as a consequence, the computed spectrum calculated in the presence of the solvent was in good agreement with the experimental determinations. The first two absorptions were found to originate from mixed platinum‐SCN (or NSC) to bipyridyl‐π* transitions rather than pure metal‐to‐ligand‐charge‐transfer (MLCT) transitions, whereas the higher‐energy bands arose from intraligand π→π* transitions. The stretching frequencies of C≡N have been calculated both in the ground and excited states, which are relative to the charge transition during the excitation. In addition, different sizes of basis sets were also discussed in this paper.
Effect of Concentration of Structurally‐Different Carboxylic Acids on Growth and Aggregation of Calcium Oxalate in Gel Systems
Authors: Deng Sui‐Ping , Ouyang Jian‐Ming
Published: September 2007

The effect of concentration of structurally‐different carboxylic acids such as ethylene diamine tetraacetic acid (H4edta), citric acid (H3cit), tartaric acid (H2tart), and acetic acid (HOAc) on growth and aggregation of calcium oxalate (CaOxa) in gel systems was comparatively investigated. H2tart and H3cit could change the morphology of calcium oxalate monohydrate (COM) and induce the formation of calcium oxalate dihydrate (COD). H4edta could induce the formation of COD at a lower concentration of 0.33 mmol/L and have the strongest ability to inhibit aggregation of COM. HOAc inhibited COM aggregation only at a higher concentration than 500 mmol/L. With increasing the number of carboxylic groups in an acid or increasing the concentration of carboxylic acid, the capacity of this acid to induce COD formation and to inhibit growth and aggregation of COM crystals increased. That is, this capacity followed the order:H4edta>H3cit>H2tart>>HOAc. The result in this work suggested that the presence of H3cit and H2tart in urine played a role in the natural defense against stone formation.
Hormone replacement therapy and lung cancer risk in Chinese
Authors: Chen Kuan‐Yu , Hsiao Chin‐Fu , Chang Gee‐Chen , Tsai Yin‐Huang , Su Wu‐Chou , Perng Reury‐Perng , Huang Ming‐Shyan , Hsiung Chao A. , Chen Chien‐Jen , Yang Pan‐Chyr ,   the GEFLAC Study Group
Published: September 2007

BACKGROUND.

The association between hormone replacement therapy (HRT) and a reduced lung cancer risk has been reported in previous studies. There is a high female to male ratio in Chinese lung cancer patients, and female patients have different clinicopathological characteristics compared with Western patient populations. The authors investigated whether HRT may reduce lung cancer risk in Taiwan.

METHODS.

The authors used a case‐control study design to investigate 826 women with lung cancer and 531 healthy controls. Personal interviews based on a structured questionnaire were performed to collect information on HRT use of at least 3 months, age, ethnicity, active and passive smoking, exposure to air pollution, cooking or incense fumes, body mass index (BMI), menopause, and family history of cancers.

RESULTS.

HRT use was associated with reduced lung cancer risk with a multivariate, adjusted odds ratio of 0.70 (95% CI, 0.53–0.94; P = .019). HRT use was associated with reduced odds ratio of lung cancer in all subset analyses stratified by histology, active and passive cigarette smoking, BMI, history of incense burning, cooking, and motorcycle riding, as well as family history of certain cancers.

CONCLUSIONS.

This study confirmed that HRT is associated with a reduced lung cancer risk. The results appeared to be applicable to Chinese female population groups. Cancer 2007. © 2007 American Cancer Society.
High dimensional model representation for piece‐wise continuous function approximation
Authors: Chowdhury Rajib , Rao B. N. , Prasad A. Meher
Published: September 2007

High dimensional model representation (HDMR) approximates multivariate functions in such a way that the component functions of the approximation are ordered starting from a constant and gradually approaching to multivariance as we proceed along the terms like first‐order, second‐order and so on. Until now HDMR applications include construction of a computational model directly from laboratory/field data, creating an efficient fully equivalent operational model to replace an existing time‐consuming mathematical model, identification of key model variables, global uncertainty assessments, efficient quantitative risk assessments, etc. In this paper, the potential of HDMR for tackling univariate and multivariate piece‐wise continuous functions is explored. Eight numerical examples are presented to illustrate the performance of HDMR for approximating a univariate or a multivariate piece‐wise continuous function with an equivalent continuous function. Copyright © 2007 John Wiley & Sons, Ltd.
The JAK/STAT pathway regulates proximo‐distal patterning in Drosophila
Authors: Ayala‐Camargo Aidee , Ekas Laura A. , Flaherty Maria Sol , Baeg Gyeong‐Hun , Bach Erika A.
Published: September 2007

unpaired, wingless, and decapentaplegic have independent expression domains. unpaired (upd) (green), wingless (Wg) (red) and decapentaplegic (dpp) (blue) do not overlap in a Drosophila third instar antennal disc. In this issue, Ayala‐Camargo et al. show that these factors mutually repress each other's expression and that this repression is critical for the formation of a single proximo‐distal axis per leg or antenna. upd‐Gal4, UAS‐gfp enhancer trap (green); Wg protein (red) and dpp‐lacZ (anti Beta‐galactosidase) (blue). Anterior is to the left and dorsal is up. See Ayala‐Camargo et al., Developmental Dynamics 236:2721‐2730. © 2007 Wiley‐Liss, Inc.
Synthesis and Structure of Tetrameric Gallium(I) Amides
Authors: Seifert Annekathrin , Linti Gerald
Published: September 2007

The amino substituted gallatetrahedranes described herein, Ga4(tmp)4 [tmp = 2,2,6,6‐(tetramethylpiperidino)] and Ga4[N(SiMe3)dipp]4 (dipp = 2,6‐diisopropylphenyl), are the first oligomeric gallium(I) amides to be reported. These compounds are formed in a facile manner from “GaI”. A new hexagallane with an unusual structure is also described. The clusters were characterized by NMR and UV/Vis spectroscopy, single‐crystal X‐ray crystallography, and DFT calculations.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Computational fluid dynamics of stented intracranial aneurysms using adaptive embedded unstructured grids
Authors: Appanaboyina S. , Mut F. , Löhner R. , Putman C. M. , Cebral J. R.
Published: September 2007

Recently, there has been increased interest in the use of stents as flow diverters in the endovascular treatment of cerebral aneurysms as an alternative to surgical clipping or endovascular embolization with coils. The aim of aneurysm stenting is to block the flow into the aneurysm in order to clot the blood inside the aneurysm and effectively isolate it from the circulation and prevent bleeding from the aneurysm. A hybrid meshing approach that combines body‐fitted grids for the vessels and adaptive embedded grids for the stents is proposed and analyzed. This strategy simplifies considerably the geometry modeling problem and allows accurate patient‐specific hemodynamic simulations with endovascular devices. This approach is compared with the traditional body‐fitted approach in the case of the flow around a circular cylinder at representative Reynolds number and an idealized aneurysm model with a stent. A novel technique to map different stent designs to a given patient‐specific anatomical model is presented. The methodology is demonstrated on a patient‐specific hemodynamic model of an aneurysm of the internal carotid artery constructed from a 3D rotational angiogram and stented with two different stent designs. The results show that the methodology can be successfully used to model patient‐specific anatomies with different stents thereby making it possible to explore different stent designs. Copyright © 2007 John Wiley & Sons, Ltd.
Functional consequences of S1P receptor modulation in rat oligodendroglial lineage cells
Authors: Jung C. G. , Kim H. J. , Miron V. E. , Cook S. , Kennedy T. E. , Foster C. A. , Antel J. P. , Soliven B.
Published: September 2007

Fingolimod (FTY720) and its phosphorylated form FTY720P are modulators of sphingosine‐1‐phosphate (S1P) receptors, which are G‐protein coupled receptors linked to cell migration and vascular maturation. The efficacy of FTY720 in autoimmune diseases such as multiple sclerosis and its animal models has been attributed to its inhibition of lymphocyte trafficking to target organs. In this study, we examined the role of S1P receptors in cultured rat oligodendrocytes (OLGs) and OLG progenitor cells (OPCs) using the active phosphorylated form of FTY720. We found that (1) FTY720P improves the survival of neonatal rat OLGs during serum withdrawal, which is associated with the phosphorylation of extracellular signal regulated kinases (ERK1/2) and Akt; (2) FTY720P regulates OPC differentiation into OLGs in a concentration‐dependent manner; and (3) S1P receptors are differentially modulated by platelet‐derived growth factor (PDGF) resulting in downregulation of S1P5 and upregulation of S1P1 in OPCs. In addition, siRNA studies revealed that S1P1 participates in PDGF‐induced OPC mitogenesis. We conclude that S1P1 and S1P5 serve different functions during oligodendroglial development, and possibly during remyelination. © 2007 Wiley‐Liss, Inc.
R‐CHOP‐14 in patients with diffuse large B‐cell lymphoma younger than 70 years: a multicentre, prospective study
Authors: Rueda Antonio , Sabin Pilar , Rifá Juli , Llanos Marta , Gómez‐Codina José , Lobo Francisco , García Ramón , Herrero Joaquin , Provencio Mariano , Jara Carlos
Published: September 2007

Several studies have shown that adding rituximab to CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) or reducing the interval between chemotherapy cycles from 3 weeks to 2 weeks improves survival in patients with diffuse large B‐cell lymphoma (DLBCL). These studies prompted our group (GOTEL) to evaluate prospectively in a pilot study the feasibility and efficacy of R‐CHOP‐14 in patients with DLBCL. Patients (<70 years) with stage II bulky or stage III or IV DLBCL and no significant comorbidities were included in the study. Rituximab was administered on day 1 before chemotherapy. R‐CHOP was given every 14 days. All patients received filgrastim (5 µg/kg) from days 4 to 10. From May 2002 to August 2004, 80 patients were recruited. Median age was 53 years and 58 patients were <60 years. According to the age‐adjusted international prognostic index (aaIPI), 13 patients (16%) had low‐risk disease, 31 (39%) low‐to‐intermediate risk, 27 (34%) high‐to‐intermediate risk and 9 (11%) high‐risk disease. Grade 3–4 neutropenia was observed in 15 patients (17.5%) and grade 3–4 infections in 13 patients (16%). After therapy, 58 patients (73%) achieved CR‐CRu (95% CI: 55–90%). With a median follow‐up of 26 months, progression‐free survival (PFS) and overall survival (OS) at 30 months were 72% and 86%, respectively. Administration of R‐CHOP‐14 is feasible and effective in patients <70 years. Copyright © 2007 John Wiley & Sons, Ltd.
Genesis of arsenic in groundwater of North Bengal Plain using PCA: A case study of English Bazar Block, Malda District, West Bengal, India
Authors: Sikdar P. K. , Chakraborty Surajit
Published: September 2007

The study area is located on the western part of the alluvium‐filled gap between the Rajmahal hills on the west and the Garo hills on the east. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternary alluvial sediments. Three hydrochemical facies with distinct characteristics have been identified which are dominated in general by alkaline earths and weak acids. The major‐ion chemistry of the area is controlled by weathering of silicate minerals, rainfall recharge, ion‐exchange processes and anthropogenic activities such as irrigation return flow and the application of inorganic fertilizers and pesticides. A stoichiometric approach suggests that mineral dissolution and anthropogenic activities contribute 79% and 21% of the total cations dissolved in groundwater. Principal component analysis (PCA) of 42 groundwater samples using 13 chemical parameters indicates that the combined processes of recharge of groundwater from rainfall, sediment water interaction, groundwater flow, infiltration of irrigation return water (which is arsenic rich due to the use of arsenic‐bearing pesticides, wood preservatives, etc. and the pumping of arsenic‐rich groundwater for agriculture purpose), oxidation of natural or anthropogenic organic matter and the reductive dissolution of ferric iron and manganese oxides play a key role in the evolution of groundwater in the study area. Factor 2 scores, associated with the infiltration of irrigation return water and spatial distribution of arsenic concentration reveal that the groundwater of the municipal area will not be affected by arsenic in the future in spite of heavy groundwater abstraction. Another PCA with geologic, geomorphic, anthropogenic, geochemical and landuse factors indicates that arsenic concentration in groundwater increases with increasing area of mango orchards, sand lithofacies and nitrate and decreases with increasing distance of paleochannel from the monitored well and depth of bore wells. High loading on nitrate may be attributed to the use of fertilizer, pesticides, etc. in mango orchards and agricultural land. High loadings on logpCO2, mango orchards (with negative sign) and phosphate (with positive sign) indicate that mango orchards provide the organic waste material which is decomposed to form organic carbon. The organic carbon undergoes oxidative carbon degeneration by different oxidants and increases the concentration of CO2in the aquifer. The reducing condition thus developed in the aquifer helps to dissolve the arsenic adsorbed on iron hydroxide or oxy‐hydroxide coated margins of sand, iron rich heavy mineral grain margins, clay minerals and Fe–Mn concretions present in the aquifer matrix. Copyright © 2007 John Wiley & Sons, Ltd.
Does the Chinese interest rate follow the US interest rate?
Authors: Cheung Yin‐Wong , Tam Dickson C. , Yiu Matthew S.
Published: September 2007

One argument for floating the Chinese renminbi (RMB) is to insulate China's monetary policy from the US effect. However, we note that both theoretical considerations and empirical results do not offer a definite answer on the link between exchange rate arrangement and policy dependence. We examine the empirical relevance of the argument by analysing the interactions between the Chinese and the US interest rates. Our empirical results, which appear robust to various assumptions of data persistence, suggest that the US effect on the Chinese interest rate is quite weak. Apparently, even with its de facto peg to the US dollar, China has alternative measures to retain its policy independence and de‐link its interest rates from the US rate. In other words, the argument for a flexible RMB to insulate China's monetary policy from the US effect is not substantiated by the observed interest rate interactions. Copyright © 2007 John Wiley & Sons, Ltd.
Bioactivity and osteoblast responses of novel biomedical nanocomposites of bioactive glass nanofiber filled poly(lactic acid)
Authors: Kim Hae‐Won , Lee Hae‐Hyoung , Chun Gae‐Sig
Published: September 2007

Biomedical nanocomposites constituted of bioactive ceramic and resorbable polymer have shown promise for the successful regeneration of bone tissues. We developed herein a novel nanocomposite made up of a bioactive glass in a nanofibrous form and a degradable synthetic polymer, poly(lactic acid) (PLA). The glass nanofiber with a bioactive composition was generated via an electrospinning process with an average diameter of ∼320 nm. The nanofiber was homogenized with PLA solution at various concentrations (up to 35% nanofiber), followed by drying and thermal pressing to produce dense nanocomposites. The nanocomposites showed an internal morphology of uniformly dispersed nanofibers within the PLA matrix. The nanocomposites induced rapid formation of a hydroxycarbonate apatite layer on the surface under a simulated physiological medium. As the amount of bioactive nanofiber increased (from 5 to 25%), the in vitro bioactivity of the nanocomposite was improved. The osteoblast responses to the nanocomposites (compositions with 5 and 25% nanofiber) were assessed in terms of cell proliferation, differentiation, and mineralization. Osteoblasts attached and grew well on the nanocomposites and secreted collagen protein at initial culturing periods. The differentiation of cells, as assessed by the expression of alkaline phosphatase, was significantly improved on the nanocomposites as compared to those on pure PLA. Moreover, the mineralized product by the cells was observed to be significantly higher on the nanocomposites with respect to pure PLA. The newly developed nanocomposite constituted of bioactive nanofiber and degradable polymer is considered as a promising bone regeneration matrix with its excellent bioactivity and osteoblast responses. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Study of the effects of tissue reactions on the function of implanted glucose sensors
Authors: Dungel Paul , Long Nathan , Yu Bazhang , Moussy Yvonne , Moussy Francis
Published: September 2007

The relationship between tissue reactions to a subcutaneously implanted glucose sensor and the function of the sensor was evaluated over a period of 4‐weeks using tubular, porous polyvinyl alcohol (PVA) sponges implanted subcutaneously in rats. The PVA sponges were used as scaffolds in which the foreign body response could develop. Coil‐type glucose sensors were then placed in the center of the PVA sponges and tested on day 3, and weekly thereafter. In the first approach, the sensors were placed in the sponges still implanted in the rats and tested. In vivo glucose sensor sensitivity peaked at day 7 and steadily decreased until day 35. In the second approach, the sensors were placed in the explanted sponges and then tested. This test showed no sensor function after day 7, indicating that functional blood vessels are critical in maintaining any function whatsoever. In both cases the sensors themselves were never implanted to eliminate any potential in vivo degradation of the sensors that could have affected the outcome of this study. Sensors were then tested in absence of sponges and found to be working properly with no change from preimplantation sensitivity. Once sensor testing was concluded, the PVA sponge/tissue samples were prepared for quantitative histological analysis. It was determined that the increase in collagen deposition within the sponge correlated with the decrease in sensor sensitivity. It was also observed that natural angiogenesis (peak at day 14) did not overcome the barrier to glucose diffusion created by the fibrous capsule. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
The granulocyte colony stimulating factor (G‐CSF) activates Jak/STAT and MAPK pathways in a trophoblastic cell line
Authors: Marino Verónica Julieta , Roguin Leonor Patricia
Published: September 2007

Granulocyte colony‐stimulating factor receptor (G‐CSFR) has been found in placenta tissues, although its functional role has not yet been defined. In order to explore the molecular pathways induced by G‐CSF in this tissue, we first reveal the presence of G‐CSFR in the JEG‐3 human trophoblastic cell line and then examined the phosphorylation of Janus tyrosine kinases (Jak), signal transducers and activators of transcription (STAT) proteins and mitogen‐activated protein kinases (MAPK) after G‐CSF binding to receptors. We showed that Jak1, Jak2, Tyk2, and STAT3 were phosphorylated after incubation with G‐CSF. Phosphorylation of p38 and p44/42 MAPK was also activated by G‐CSF, and specifically blocked in the presence of the corresponding inhibitors. Similar intracellular pathways were induced by G‐CSF in a myeloid leukemia NFS‐60 cell line that was studied in parallel. Conversely to cytokine action in myeloid cells, G‐CSF did not induce a proliferative response in JEG‐3 cells. When the effect of G‐CSF on cellular viability was evaluated, cytokine‐stimulated JEG‐3 cells were protected from foetal serum starvation. In addition, when JEG‐3 cells deprived of serum were incubated at different times in the presence of G‐CSF, a progressive decrease in the percentage of hypodiploid cells was observed. In summary, we identified the molecular pathways activated after G‐CSF binding to trophoblastic cell receptors and showed that G‐CSF behaved as a protective cytokine, which supports JEG‐3 cells survival. J. Cell. Biochem. 103: 1512–1523, 2008. © 2007 Wiley‐Liss, Inc.
Signaling of DNA damage is not sufficient to induce p53 response: (Re)Activation of wt p53 protein strongly depends on cellular context
Authors: Węsierska‐Gądek Józefa , Gueorguieva Marieta , Komina Oxana , Schmid Gerald , Kramer Matthias P.
Published: September 2007

It is generally accepted that exposure of cells to a variety of DNA‐damaging agents leads to up‐regulation and activation of wild‐type (wt) p53 protein. We investigated the (re)‐activation of p53 protein in two human cancer cell lines in which the gene for this tumor suppressor is not mutated: HeLaS3 cervix carcinoma and MCF‐7 breast cancer cells, by induction via different genotoxic and cytotoxic stimuli. Treatment of human cells with the alkylating agent N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) or different anti‐cancer drugs resulted in a strong DNA damage as evidenced by Comet assay and a marked increase in site‐specific phosphorylation of H2AX. Unlike in MCF‐7 cells, in HeLaS3 cells the expression of p53 protein did not increase after MNNG treatment despite a strong DNA damage. However, other agents for example doxorubicin markedly induced p53 response in HeLaS3 cells. After exposure of these cells to MNNG, the ATM‐dependent effector proteins Chk2 and NBS1 were phosphorylated, thereby evidencing that MNNG‐induced DNA breakage was recognized and properly signaled. In HeLaS3 cells wt p53 protein is not functional due to E6‐mediated targeting for accelerated ubiquitylation and degradation. Therefore, the activation of a p53 response to genotoxic stress in HeLaS3 cells seems to depend on the status of E6 oncoprotein. Indeed, the induction of p53 protein in HeLaS3 cells in response to distinct agents inversely correlates with the cellular level of E6 oncoprotein. This implicates that the capability of different agents to activate p53 in HeLaS3 cells primarily depends on their inhibitory effect on expression of E6 oncoprotein. J. Cell. Biochem. 103: 1607–1620, 2008. © 2007 Wiley‐Liss, Inc.
Conformational memories with variable bond angles
Authors: Whitnell Robert M. , Hurst Dow P. , Reggio Patricia H. , Guarnieri Frank
Published: September 2007

Conformational Memories (CM) is a simulated annealing/Monte Carlo method that explores peptide and protein dihedral conformational space completely and efficiently, independent of the original conformation. Here we extend the CM method to include the variation of a randomly chosen bond angle, in addition to the standard variation of two or three randomly chosen dihedral angles, in each Monte Carlo trial of the CM exploratory and biased phases. We test the hypothesis that the inclusion of variable bond angles in CM leads to an improved sampling of conformational space. We compare the results with variable bond angles to CM with no bond angle variation for the following systems: (1) the pentapeptide Met‐enkephalin, which is a standard test case for conformational search methods; (2) the proline ring pucker in a 17mer model peptide, (Ala)8Pro(Ala)8; and (3) the conformations of the Ser 7.39 χ1 in transmembrane helix 7 (TMH7) of the cannabinoid CB1 receptor, a 25‐residue system. In each case, analysis of the CM results shows that the inclusion of variable bond angles results in sampling of regions of conformational space that are inaccessible to CM calculations with only variable dihedral angles, and/or a shift in conformational populations from those calculated when variable bond angles are not included. The incorporation of variable bond angles leads to an improved sampling of conformational space without loss of efficiency. Our examples show that this improved sampling leads to better exploration of biologically relevant conformations that have been experimentally validated. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Effect of microbial transglutaminase on the protein fractions of rice, pea and their blends
Authors: Marco Cristina , Pérez Gabriela , Ribotta Pablo , Rosell Cristina M
Published: September 2007

BACKGROUND: Transglutaminase (TG) is a transferase that has been used for crosslinking proteins. In general, those interactions are promoted within proteins of the same nature, and very few studies have been conducted for creating new bonds between proteins from different sources catalysed by TG. The effect of TG on the protein fractions of rice flour, pea protein isolate and their blends was studied by using different electrophoretic analyses (simple sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) and multistaking SDS‐PAGE under reducing and non‐reducing conditions).

RESULTS: TG induced the disappearance of numerous protein bands as a consequence of the formation of large protein polymers, linked by isopeptidic and disulfide bonds, with reduced solubility. The main protein fractions involved in those interactions were the albumins and globulins, from the pea protein isolate, and the rice flour; and the glutelins were also crosslinked.

CONCLUSION: Composite flours containing the rice flour and the pea protein isolate are proposed for obtaining a protein‐enriched dough with better amino acid balance. Also a protein network formed of protein aggregates of high molecular weight can be created in the presence of transglutaminase. Copyright © 2007 Society of Chemical Industry