bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of novel biodegradable unsaturated poly(ester amide)s
Authors: Guo Kai , Chu C. C. , Chkhaidze E. , Katsarava R.
Published: February 2005

A series of novel biodegradable unsaturated poly(ester amide)s (UPEAs) were synthesized through the solution polycondensation of two unsaturated monomers, di‐p‐nitrophenyl fumarate and L‐phenylalanine 2‐butene‐1,4‐diol diester p‐toluene sulfonate, and four other saturated monomers in different combinations. The UPEAs were obtained in fairly good yields with N,N‐dimethylacetamide (DMA) as the solvent. The number‐average and weight‐average molecular weights of the UPEAs, measured by gel permeation chromatography, ranged from 10 to 30 kg/mol, they had a rather narrow molecular weight distribution of 1.40. The chemical structures of the novel biodegradable UPEAs were confirmed by both IR and NMR spectra. The UPEAs had higher glass‐transition temperatures than saturated PEAs of similar structures, and their glass‐transition temperatures were affected more by the CC double bond located in the diamide part than by those in the diester part. The solubility of the polymers was poor in water but better in DMA and dimethyl sulfoxide. With the availability of these inherent CC double bonds in the UPEA backbones, these UPEAs have the functionality of CC bonds, such as photochemical reactivity or the ability to react with or be modified by other bioactive or other environmentally sensitive compounds, and this can easily extend their applications to biomedical and pharmaceutical areas. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1463–1477, 2005
Donor–acceptor copolymers for red‐ and near‐infrared‐emitting polymer light‐emitting diodes
Authors: Thompson Barry C. , Madrigal Luis G. , Pinto Mauricio R. , Kang Tae‐Sik , Schanze Kirk S. , Reynolds John R.
Published: February 2005

We report a comparative study of two organic soluble, vinylene‐based, alternating donor–acceptor copolymers with 1,4‐(2,5‐dihexadecyloxyphenylene) as the donor; the acceptor is either a 2,5‐linked pyridine or a 5,8‐linked 2,3‐diphenylpyrido[3,4‐b]pyrazine. The polymers are synthesized via a Heck coupling methodology from a dihalo monomer and a divinyl monomer to yield number‐average molecular weights of 16,000 g/mol for the pyridine polymer (PPyrPV) and 6500 g/mol for the pyridopyrazine polymer (PPyrPyrPV), with high solubility in common chlorinated solvents and lower solubility in less polar solvents (e.g., tetrahydrofuran). Thin‐film measurements show band gaps of 2.2 and 1.8 eV for PPyrPV and PPyrPyrPV, respectively. Both polymers exhibit photoluminescence in solution and in the solid state and exhibit electroluminescence when incorporated into light‐emitting diodes. In this case, a broad red emission centered at 690 nm for PPyrPV and a near‐infrared emission centered at 800 nm for PPyrPyrPV have been observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1417–1431, 2005
New poly(amidoamine)s containing disulfide linkages in their main chain
Authors: Emilitri Elisa , Ranucci Elisabetta , Ferruti Paolo
Published: February 2005

Novel poly(amidoamine)s (PAAs) containing disulfide linkages regularly arranged along their backbones were synthesized by the stepwise polyaddition of 2‐methylpiperazine to N,N′‐bis(acryloyl)cystamine (BACy1) or N,N′‐bis(acryloyl)‐(L)‐cystine (BACy2). Both bisacrylamides had, in turn, been obtained by the reaction of acryloyl chloride with the corresponding amines. All the products were characterized with 1H and 13C NMR spectroscopy, and the average molecular weights of the polymers were determined by size exclusion chromatography. Both PAAs showed different solubility properties. In particular, PAA‐Cy1, derived from BACy1, was sparingly soluble in water, whereas PAA‐Cy2, derived from BACy2, was very soluble in aqueous media. The polymerization rates were investigated with 1H NMR spectroscopy. In both cases, the experimental data were consistent with pseudo‐second‐order kinetics. The calculated kinetic constants were 5.96 × 10−3 and 5.90 × 10−2 min−1 L mol−1 for the polyaddition of BACy1 and BACy2, respectively. The observed hydrolytic degradation rate of PAA‐Cy2 in a pH 7.4 tris(hydroxymethyl)aminomethane (TRIS) buffer was comparable to that of conventional amphoteric PAAs, that is, PAAs containing carboxyl groups in their repeating unit. Degradation experiments carried out in the presence of 2‐mercaptoethanol with both PAAs demonstrated that the disulfide groups contained in its repeating units were susceptible to reductive cleavage in the presence of thiols. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1404–1416, 2005
Atom transfer radical polymerization of styrenic ionic liquid monomers and carbon dioxide absorption of the polymerized ionic liquids
Authors: Tang Huadong , Tang Jianbin , Ding Shijie , Radosz Maciej , Shen Youqing
Published: February 2005

Polymeric forms of ionic liquids have many potential applications because of their high thermal stability and ionic nature. Two ionic liquid monomers, 1‐(4‐vinylbenzyl)‐3‐butyl imidazolium tetrafluoroborate (VBIT) and 1‐(4‐vinylbenzyl)‐3‐ butyl imidazolium hexafluorophosphate (VBIH), were synthesized through the quaternization of N‐butylimidazole with 4‐vinylbenzylchloride and a subsequent anion‐ exchange reaction with sodium tetrafluoroborate or potassium hexafluorophosphate. Copper‐mediated atom transfer radical polymerization was used to polymerize VBIT and VBIH. The effects of various initiator/catalyst systems, monomer concentrations, solvent polarities, and reaction temperatures on the polymerization were examined. The polymerization was well controlled and exhibited living characteristics when CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine or CuBr/2,2′‐bipyridine was used as the catalyst and ethyl 2‐bromoisobutyrate was used as the initiator. Characterizations by thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction showed that the resulting VBIT polymer, poly[1‐(4‐vinylbenzyl)‐3‐butyl imidazolium tetrafluoroborate] (PVBIT), was amorphous and had excellent thermal stability, with a glass‐transition temperature of 84 °C. The polymerized ionic liquids could absorb CO2 as ionic liquids: PVBIT absorbed 0.30% (w/w) CO2 at room temperature and 0.78 atm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1432–1443, 2005
Synthesis of poly(methyl methacrylate)‐b‐poly(vinyl chloride)‐b‐poly(methyl methacrylate) block copolymers by CuCl/2,2′‐bipyridine‐catalyzed living radical block copolymerization initiated from α,ω‐di(iodo)poly(vinyl chloride) prepared by single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization
Authors: Percec Virgil , Guliashvili Tamaz , Popov Anatoliy V. , Ramirez‐Castillo Ernesto
Published: February 2005

α,ω‐Di(iodo)poly(vinyl chloride)s with number‐average molecular weights (Mn's) of 2100–29,800 and weight‐average molecular weight/number‐average molecular weight (Mw/Mn) ratios of 1.66–2.16 were synthesized by the single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride initiated with CHI3 and catalyzed by Na2S2O4. These α,ω‐di(iodo)poly(vinyl chloride)s were used as initiators for the metal‐catalyzed living radical block copolymerization of methyl methacrylate mediated by CuCl/2,2′‐bipyridine. Poly(methyl methacrylate)‐b‐poly(vinyl chloride)‐b‐poly(methyl methacrylate) block copolymers with Mn values of 36,500–95,700 and Mw/Mn values lower than 1.20 were synthesized by this novel and general synthetic method. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1478–1486, 2005
Electrosyntheses of freestanding polyindole films in boron trifluoride diethyl etherate
Authors: Xu Jingkun , Nie Guangming , Zhang Shusheng , Han Xuejun , Hou Jian , Pu Shouzhi
Published: February 2005

High‐quality freestanding polyindole (PIn) films were synthesized electrochemically through the direct oxidation of indole in pure boron trifluoride diethyl etherate (BFEE). The oxidation potential of indole in this medium was measured to be only 0.86 V versus a saturated calomel electrode, which was lower than that determined in acetonitrile/0.1 mol L−1 Bu4NBF4. PIn films obtained from this medium showed better electrochemical behavior and better thermal stability with a conductivity of 10−1 S cm−1, and this indicated that BFEE was a better medium than acetonitrile for the electrosyntheses of PIn films. Structural studies showed that the polymerization of indole ring occurred at the 2,3‐position. As‐formed PIn films could be partly dissolved in acetone, acetonitrile, tetrahydrofuran, and so forth. Fluorescent spectral studies indicated that PIn was a good blue‐light emitter. To the best of our knowledge, this is the first report on the fluorescence of PIn. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1444–1453, 2005
Block and random copolymers as surfactants for dispersion polymerization. I. Synthesis via atom transfer radical polymerization and ring‐opening polymerization
Authors: Jakubowski Wojciech , Lutz Jean‐François , Slomkowski Stanislaw , Matyjaszewski Krzysztof
Published: February 2005

Atom transfer radical polymerization (ATRP) and ring‐opening polymerization (ROP) were combined to synthesize poly(ϵ‐caprolactone‐co‐octadecyl methacrylate‐co‐dimethylaminoethyl methacrylate) copolymers possessing a triblock or random block structure. Various synthetic pathways (sequential or simultaneous approaches) were investigated for the synthesis of both copolymers. For the preparation of these copolymers, an initiator with dual functionality for ATRP/anionic ring‐opening polymerization, 2‐hydroxyethyl 2‐bromoisobutyrate, was used. Copolymers were prepared with good structural control and low polydispersities (weight‐average molecular weight/number‐average molecular weight < 1.2), but one limitation was identified: the dimethylaminoethyl methacrylate (DMAEMA) block had to be synthesized after the ϵ‐caprolactone block. ROP could not proceed in the presence of DMAEMA because the complexation of the amine groups in poly(dimethylaminoethyl methacrylate) deactivated tin(II) hexanoate, which was used as a catalyst for ROP. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1498–1510, 2005
Conservation of natural enemies in cotton: comparative selectivity of acetamiprid in the management of Bemisia tabaci
Authors: Naranjo Steven E , Akey David H
Published: February 2005

The integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in agricultural systems. A two‐year field study was conducted to evaluate the selectivity of acetamiprid for the control of Bemisia tabaci (Gennadius) in cotton compared with a proven selective regime based on the insect growth regulators (IGRs) pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B tabaci compared with an untreated control, and generally produced lower pest densities than the IGR regime. Univariate analyses indicated that nine of 17 taxa of arthropod predators were significantly depressed with the use of acetamiprid compared with an untreated control, including common species such as Geocoris punctipes (Say), Orius tristicolor (White), Chrysoperla carnea Stephens sensu lato, Collops vittatus (Say), Hippodamia convergens Guérin‐Méneville, and Drapetis nr divergens. Compared with results from independent, concurrent studies using mixtures of broad‐spectrum insecticides at the same research site, acetamiprid depressed populations of fewer predator taxa; but, for eight predator taxa significantly affected by both regimes, the average population reduction was roughly equal. In contrast, only four taxa were significantly reduced in the IGR regime compared with the untreated control and three of these were omnivores that function primarily as plant pests. Principal response curves analyses (a time‐dependent, multivariate ordination method) confirmed these patterns of population change for the entire predator community. Predator:prey ratios generally increased with the use of both IGRs and acetamiprid compared with an untreated control, but ratios were consistently higher with IGRs. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Because of its high efficacy, acetamiprid may play an important role in later stages of B tabaci control where less emphasis is placed on selectivity. However, our results suggest that acetamiprid would be a poor substitute for the currently used IGRs in the initial stage of control where insecticide selectivity is crucial to a functional integrated control program for B tabaci in cotton. Published in 2005 for SCI by John Wiley & Sons, Ltd.
Inheritance of resistance and cross‐resistance to deltamethrin in Plutella xylostella (Lepidoptera: Plutellidae) from Pakistan
Authors: Sayyed Ali H , Attique M Naveed R , Khaliq Abdul , Wright Denis J
Published: February 2005

A field population of Plutella xylostella (L) from Pakistan was found to be highly resistant to deltamethrin (>500‐fold) but had little or no resistance to spinosad, fipronil, indoxacarb, abamectin, Bacillus thuringiensis (Bt) var kurstaki, Bt var aizawai or Cry1Ac when compared with a susceptible laboratory population, Lab‐UK. A sub‐population was selected for six generations (laboratory G3–G8) with deltamethrin (delta‐SEL), while a second sub‐population was left unselected (UNSEL). Bioassays at G9 found that selection with deltamethrin gave resistance ratios of >230 compared with UNSEL (>6730 compared with Lab‐UK). The delta‐selected population showed no apparent cross‐resistance to spinosad, fipronil or indoxacarb. Logit regression analysis of F1 reciprocal crosses between delta‐SEL and Lab‐UK indicated that resistance to deltamethrin in the delta‐SEL population was inherited as an autosomal, incompletely dominant (DLC = 0.67) trait. A direct test of monogenic inheritance based on a back‐cross of F1 progeny with delta‐SEL suggested that resistance to deltamethrin was controlled by more than one factor. Copyright © 2005 Society of Chemical Industry
Response of multiple seeded cocklebur and other cocklebur types to herbicide treatment
Authors: Abbas Hamed K , Johnson Bobbie J , Pantone Dan J , Wax Loyd M , Hine Ron , Shier W Thomas
Published: February 2005

Multiple seeded cocklebur has been found in the last decade in Texas, and described as a biotype of Xanthium strumarium L with up to 25 seeds per bur instead of the usual two. The multiple seeded bur typically produces up to nine seedlings, causing concern that it may be harder to control than normal seeded common cocklebur. The efficacies of a series of fungal and conventional commercial herbicides have been compared in the greenhouse on seedlings of multiple seeded cocklebur from Texas (MSC‐TX) and normal common cockleburs from Texas (NCC‐TX), Arkansas (NCC‐AR), Illinois (NCC‐ILL) and two from Mississippi (NCC‐MS#1, NCC‐MS#2). Three measures of herbicidal activity (reductions in plant height and dry weight, and mortality) were used. The fungal herbicide Alternaria helianthi (Hansf) Tubaki & Nishihara at 1 × 105 conidia ml−1 + 2 g liter−1 Silwet L‐77 with an 8‐h dew period was an effective herbicide with all biotypes, as were the commercial chemical herbicides chlorimuron (14.8 g ha−1), imazaquin (29.6 g ha−1), sodium hydrogen methylarsonate (MSMA; 279.1 g ha−1) and imazethapyr (39.5 g ha−1). The membrane‐disrupting organic arsenical MSMA was effective with all biotypes, whereas commercial chemical herbicides which act by inhibiting branched‐chain amino acid synthesis (chlorimuron, imazaquin and imazethapyr) were less effective against normal seeded common cocklebur biotypes with short stature. These studies showed that multiple seeded cocklebur was at least as susceptible to the biological agent A helianthi and to the conventional commercial herbicides studied as were normal seeded cockleburs, suggesting that existing methods should be adequate to control this novel biotype. Copyright © 2005 Society of Chemical Industry
State of the art in multiaxial phenomenological failure criteria for wood members
Authors: Kasal Bo , Leichti Robert J
Published: February 2005

Wood structural members are frequently subjected to loads resulting in multiaxial stress. Failure criteria ordinarily used for isotropic materials do not apply to orthotropic and anisotropic materials and their use may result in incorrect stress state interpretation. This paper summarizes the current state of the art in applying phenomenological failure criteria to wood and wood‐based materials.
Fresh and hardened properties of self‐consolidating concrete
Authors: Bonen David , Shah Surendra P
Published: February 2005

Self‐consolidating concrete, (SCC) is a new technology and the market share of its products is rapidly growing because of the economic opportunities and improvements of the quality of the concrete and the working environment. In view of the potential number of ingredients, SCC is a complex system that is usually proportioned with one or more mineral admixtures and one or more chemical admixtures. A key factor for a successful formulation is a clear understanding of the role of the various constituents in the mix and their effects on the fresh and hardened properties.

The fundamental rheological properties of SCC are based on low yield stress, moderate viscosity and retention of the kinetic energy of the flowable mix by reducing the volume fraction of coarse aggregate. These measures are necessary for imparting the requested fluidity, segregation resistance and prevention of interparticle collision and blocking. A low yield stress is attained by incorporation of adequate contents of superplasticizer. The flow characteristics are further modified by changing the aggregate volume fraction, coarse‐to‐fine aggregate volume, and the composition of the other ingredients. The viscosity is controlled by the contents of the free water, superplasticizer, and the volume fraction of the solids in the mix. The two strategies for maintaining a moderate viscosity are based on either incorporation of high amounts of powder; i.e. total content of cementitious materials (referred to as powder type SCC) or addition of viscosity modifier agents (referred to as VMA type SCC).

By analogy to the Powers and Brownyard gel–space ratio, the compressive strength can be approximated by calculating the binder‐space ratio. One of the main challenges is to impart the required rheological properties that allow desired flow and filling ability characteristics whilst retaining dynamic and static stability. With this respect, the density of the matrix and maximum size of aggregate cannot be overlooked as, within the range of practical attainable viscosities that allow a free‐flow, their effects on the resistance to segregation are as high or even greater than that of the effect of viscosity. Attention is also drawn to the higher shrinkage values of SCC, especially the inherent higher shrinkage associated with the powder type SCC.
Interface bond between FRP sheets and concrete substrates: properties, numerical modeling and roles in member behaviour
Authors: Ueda Tamen , Dai Jianguo
Published: February 2005

The success of most of strengthening or retrofitting technologies for concrete structures by using external bonded FRP sheets depends highly on the interface bond between the FRP sheets and concrete substrates. This paper reviews current studies on evaluating the bond properties of FRP sheet–concrete interfaces and, in particular, focuses on several newly developed bond models for describing the bond characteristics of FRP sheet–concrete interfaces under various loading conditions. This paper also gives several examples that apply these interfacial bond models to the design of different retrofitting cases. Analytical solutions are discussed that consider the local interfacial delamination and slip behaviour, which can improve the prediction of strength and deformation performances, as well as clarify the failure mechanisms of concrete members upgraded with FRP composites. Moreover, the improvement in structural performance of retrofitted concrete members is discussed by relating them to the optimum microscopic properties of the interface bond and the properties of retrofitting materials.
Local elastic response of individual grains in lead‐free Nb‐doped Bi4Ti3O12 piezoelectric ceramics
Authors: Zeng H. R. , Yu H. F. , Zhang L. N. , Chu R. Q. , Li G. R. , Yin Q. R.
Published: February 2005

The local elastic response of individual grains in lead‐free Nb‐doped Bi4Ti3O12 piezoelectric ceramics have been examined by atomic force microscopy in the acoustic mode. Subsurface features with different elasticity down to 60 nm are imaged from the cantilever deflection vibration at a modulation frequency much lower than the cantilever resonance. Local elastic regions parallel and perpendicular to the long axis of the plate‐like grains are found in the Bi4Ti3O12 piezoelectric ceramics, which are most likely a result of the crystal structure arrangement undergone in the grain growth of the Nb‐doped Bi4Ti3O12 piezoelectric ceramics during sintering. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of the toxicological joint effects between cyanogenic toxicants and aldehydes to Photobacterium phosphoreum
Authors: Lin Zhifen , Niu Xiaojun , Wu Chunde , Yin Kedong , Cai Zeping
Published: February 2005

In this study, a general approach is proposed that predicts the toxicological effects, to Photobacterium phosphoreum, of cyanogenic toxicants in combination with aldehydes. Forty binary mixtures containing an aldehyde and a cyanogenic toxicant were examined. The observed results indicate that the toxicological joint effects are different (additive, synergistic, or antagonistic) from each other, and the differences depend on chemical–chemical interactions between the cyanogenic toxicants and the aldehydes. Analysis of the chemical–chemical interactions reveals that there are two characteristics of individual chemicals that contribute to the joint effects: one is the charge of the carbon atom in the CHO group of aldehydes and the other is the charge of the carbon atom (C*) in the carbochain of cyanogenic toxicants. Based on these two contributors to toxicity, a quantitative structure‐activity relationship (QSAR) model can be derived, namely M=0.367−0.811σp−6.704 C* where r2=0.868, SE=0.232, F=121.769, P=0.000, M is the sum of toxic units; σp is the Hammett Constant and is used to evaluate the charge of the carbon atom in the CHO of aldehydes; C* is the charge of the carbon atom in the carbochain of cyanogenic toxicants. Application of this model to the eight other related mixtures demonstrates the consistency between the predicted and observed toxicities, with r2=0.888, SE=0.223, F=45.562 at P=0.000. This prediction capability convinces us that the QSAR model provides a general approach to prediction of the joint toxicological joint effects of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum.
The Better Predictive Model: High q2 for the Training Set or Low Root Mean Square Error of Prediction for the Test Set?
Authors: Aptula Aynur O. , Jeliazkova Nina G. , Schultz Terry W. , Cronin Mark T. D.
Published: February 2005

The process of validation of computational models (e.g., QSARs) may become the most important step in their development. Different requirements for the reliability and predictability of QSAR models have been described in the literature. Despite these formal recommendations there are few practical rules as to when to cease adding variables to a QSAR (i.e., what is an appropriate level of complexity of the model). In this work the influence of model complexity to statistical fit and error have been investigated using toxicity data for 200 phenols to the ciliated protozoan Tetrahymena pyriformis when applying a test set of a further 50 compounds. The results from this investigation showed that some important factors play a role in the definition of a good and reliable QSAR. These include the fact that q2 is not a good criterion for a model predictivity; that outliers should not necessarily be deleted as this may reduce the chemical space of the model; the number of descriptors in a multivariate model should be chosen carefully to avoid model under‐ and over‐estimation; and that an appropriate number of dimensions is required for PLS modelling.
QSAR Study of 2,3‐Benzodiazepin‐4(thi)one‐ and 1,2‐Phthalazine‐Related Negative Allosteric Modulators of the AMPA Receptor: A Structural Descriptors‐Based Reassessment
Authors: Buchwald Peter , Einstein Brandon , Bodor Nicholas
Published: February 2005

In an attempt to establish statistically more rigorous and chemically more meaningful quantitative structure‐activity relationship (QSAR) equations, a reassessment of a recent study of in vivo anticonvulsant activity for a set of 2,3‐benzodiazepin‐4(thi)one‐ and 1,2‐phthalazine‐related allosteric AMPA antagonists (n=61) is presented. Contrary to the original, relatively nonspecific descriptor set, which included, for example, a number of topological descriptors, specific structural descriptors that are much easier to interpret from a medicinal chemical point of view are used in this multiple linear regression‐based approach. Only statistically significant descriptors have been retained in the final equation, and whereas they give about the same correlation as those of the original paper on the training set (r2 of 0.79 vs. 0.76, n=49), they perform much better on the test set (predictive r$\rm{ {_{pr}^{2}}}$ of 0.73 vs. 0.05; r2 of 0.78 vs. 0.08, n=12). Descriptors found to be relevant are clearly related to substitutions at known pharmacophore positions, such as those corresponding to the 2,3‐, 7,8‐ and 4′‐positions of the benzodiazepine skeleton. Therefore, by a more careful selection of the descriptor set, both an improved prediction and a more intuitive quantitative interpretation could be achieved for this set of allosteric AMPA antagonists.
Investigations of taxoids by electrospray and atmospheric pressure chemical ionization with tandem mass spectrometry
Authors: Ye Min , Guo De‐an
Published: February 2005

The fragmentation behavior of taxoids was studied using electrospray (ESI) and atmospheric pressure chemical ionization (APCI) sources with multi‐stage tandem mass spectrometry. In the positive ion mode taxoids gave prominent [M+Na]+ and [M+K]+ ions with the ESI source, and [M+NH4]+ or [M+H]+ ions with the APCI source. The MS/MS fragmentations of ions produced by APCI and ESI sources were very similar. For both sources, the presence of cinnamoyl or benzoyl groups could be characterized by initial losses of 148 or 122 u, respectively, from molecular adduct ions. However, the elimination of cinnamic acid was relatively difficult for the molecular adduct ions formed by APCI, and was comparable in importance to the loss of acetic acid. The other fragments involved losses of CH2CO, CO, and H2O. The 5/7/6 type taxoids underwent characteristic losses of 58 or 118 u from ions produced by both APCI and ESI sources. The fragmentation behavior was remarkably influenced by substitution locations. The elimination of the C‐10 benzoyl group was usually the first fragmentation step, while that of the C‐2 benzoyl group was relatively difficult. The acetoxyl group at C‐7 was more active than those at C‐2, C‐9, and C‐10, which in turn were more active than that at C‐4. These fragmentation rules could facilitate the rapid screening and structural characterization of taxoids in plant extracts by high‐performance liquid chromatography/mass spectrometry (HPLC/MS). Copyright © 2005 John Wiley & Sons, Ltd.
On the stability of the organic dication of the bisquaternary ammonium salt decamethoxinum under liquid secondary ion mass spectrometry
Authors: Pashynska Vlada A. , Kosevich Marina V. , Gömöry Agnes , Szilágyi Zoltan , Vékey Karoly , Stepanian Stepan G.
Published: February 2005

In the course of a liquid secondary ion mass spectrometric (SIMS) investigation on a bisquaternary ammonium antimicrobial agent, decamethoxinum, unusual pathways of fragmentation of the organic dication M2+ of this bisquaternary salt, with preservation of the doubly charged state of the fragments, were observed. To reveal the structural and electronic parameters of decamethoxinum, which are responsible for the stabilization of its organic dication in the gas phase, a comprehensive SIMS study using metastable decay, collision‐induced dissociation and kinetic energy release techniques complemented by ab initio quantum chemical calculations was performed. Pathways of fragmentation of two main precursors originating from decamethoxinum—organic dication M2+ and its cluster with a Cl− counterion [M · Cl]+—and a number of their primary fragments were established and systematized. Differences in the pathways of fragmentation of M2+ and [M · Cl]+ were revealed: the main directions of [M · Cl]+ decay involve dequaternization similar to thermal degradation of this compound, while in M2+ fragmentation via loss of one and two terminal radicals with preservation of the doubly charged state of the fragments dominates over charge separation processes. It was shown that pairing of the dication with a Cl− anion does not preserve the complex from fragmentation via separation of two positively charged centers or neutralization (dequaternization) of one such center. At the same time the low abundance of M2+ in the SIMS spectra is to a larger extent controlled by a probability of M2+ association with an anion than by the decay of the dication per se.

Quantum chemical calculations of the structural and electronic parameters of the decamethoxinum dication have revealed at least three features which can provide stabilization of the doubly charged state. Firstly, in the most energetically favorable stretch conformation the distance between the quaternary nitrogens (rN1‐N2 = 1.39 nm) is relatively large. Secondly, an intramolecular solvation of quaternary groups by carbonyl oxygens of the adjacent groups of the dication occurs, which contribute to structural stabilization. Thirdly, an important feature of the electronic structure of the dication is the presence of a partial negative charge on the nitrogen atoms and smearing of a positive charge mainly over the hydrogens of alkyl groups attached to the quaternary nitrogens, which reduces the net repulsion between the quaternary groups. The possible influence of charge smearing on the kinetic energy released on the dication fragmentation is discussed. Copyright © 2005 John Wiley & Sons, Ltd.
A high‐throughput liquid chromatography/tandem mass spectrometry method for screening glutathione conjugates using exact mass neutral loss acquisition
Authors: Castro‐Perez Jose , Plumb Robert , Liang Li , Yang Eric
Published: February 2005

Chemically reactive metabolites may cause hepatotoxicity and as a result liver failure or other adverse side reactions. Therefore, this is a vital topic of interest because early reactive metabolite screening may prevent compound failure at a later stage. In order to address this issue, a screening assay has been developed to detect the formation of reactive metabolites by using glutathione as a trapping reagent, which will allow us to search for phase I metabolites and also glutathiones during in vitro metabolite screening using liquid chromatography/tandem mass spectrometry (LC/MS/MS) with exact mass. Glutathione conjugations when fragmented by the mass spectrometer give a common loss corresponding to the pyroglutamic acid moiety, which can be monitored. Until recently, this work has been carried out with triple quadrupole technology using nominal mass. The advantage of the hybrid quadrupole time‐of‐flight mass spectrometer is the selectivity and sensitivity that can be achieved. Exact neutral loss detection is achieved via sequential low‐ and high‐energy MS acquisitions. After detection of the loss of the pyroglutamic acid moiety, using a window of ±20 mDa on the high‐energy scan, MS/MS is carried out on the parent mass of interest to confirm the common neutral loss. Copyright © 2005 John Wiley & Sons, Ltd.
A tandem mass spectrometric study of saccharides at high mass resolution
Authors: March Raymond E. , Stadey Christopher J.
Published: February 2005

Nine monosaccharides and four disaccharides were mass analyzed using a quadrupole time‐of‐flight tandem mass spectrometer combined with an electrospray ionization source. Product ion mass spectra of deprotonated, protonated, and sodiated saccharides were observed and were compared within each group of saccharides. Each of the deprotonated pentoses, hexoses and disaccharides yielded a significantly different product ion mass spectrum with the exception of α‐lactose and β‐lactose. The disaccharides α‐ and β‐lactose differ only at the glycosidic linkage. Product ion mass spectra of protonated and sodiated α‐ and β‐lactose were indistinguishable also. Copyright © 2005 John Wiley & Sons, Ltd.
Liquid chromatography/tandem mass spectrometry for pharmacokinetic studies of 20(R)‐ginsenoside Rg3 in dog
Authors: Li Ke , Chen Xiaoyan , Xu Jinghua , Li Xin , Zhong Dafang
Published: February 2005

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the investigation of the pharmacokinetics of 20(R)‐ginsenoside Rg3 in dog. The plasma samples were pretreated by liquid‐liquid extraction and analyzed using LC/MS/MS with an electrospray ionization interface. Dioscin was used as the internal standard. The method had a lower limit of quantitation of 0.5 ng/mL for Rg3 in 200 μL of plasma or 2 ng/mL in 100 μL of plasma, which offered a satisfactory sensitivity for the determination of Rg3 in plasma. The intra‐ and inter‐day precisions were measured to be below 8% and accuracy between −1.5 and 1.4% for all quality control samples. This quantitation method was successfully applied to pharmacokinetic studies of Rg3 after both an oral and an intravenous administration to beagle dogs. No Rh2 and protopanaxadiol were detected in plasma. Copyright © 2005 John Wiley & Sons, Ltd.
Interactions of dopamine D1 and D2 receptor antagonists with D‐methamphetamine‐induced hyperthermia and striatal dopamine and serotonin reductions
Authors: Broening Harry W. , Morford Laronda L. , Vorhees Charles V.
Published: February 2005

The effects of the dopamine D1 receptor antagonist R(+)‐SCH‐23390 and D2 receptor antagonist S(–)‐eticlopride on d‐methamphetamine‐induced striatal monoamine reductions 72 h after treatment were investigated in relation to changes in body temperature. Rats were administered four 10‐mg/kg doses of d‐methamphetamine or saline with a 2‐h interval between treatments; 0.5 mg/kg eticlopride or SCH‐23390 was administered 15 min before each methamphetamine or saline injection. Two ambient temperature conditions were investigated: 24 and 33°C. Methamphetamine administered at 24°C induced hyperthermia and reduced striatal dopamine content by 73%; 0.5 mg/kg eticlopride or SCH‐23390 administered in combination with methamphetamine at 24°C attenuated methamphetamine‐induced hyperthermia and prevented significant reductions in dopamine content. At 33°C, eticlopride and SCH‐23390 were ineffective in blocking methamphetamine‐induced hyperthermia and dopamine content was reduced by 65% in the SCH‐23390‐methamphetamine group. By contrast, dopamine content was reduced by only 31% in the 33°C eticlopride‐methamphetamine group. Thus, although the eticlopride‐methamphetamine treatment combination at 33°C exhibited a hyperthermic response comparable to that seen with methamphetamine alone at 24°C, reductions in dopamine content were attenuated in the combination group compared with methamphetamine alone at 24°C. Serotonin changes showed similar attenuated reductions after SCH‐23390 or eticlopride pretreatment at 24°C in combination with methamphetamine, but this attenuation was absent at 33°C. The dissociation of methamphetamine‐induced striatal dopamine reduction and hyperthermia seen after eticlopride pretreatment suggests a dopamine D2 receptor mechanism in mediating methamphetamine‐induced dopamine depletion. However this D2 mechanism does not apply to methamphetamine‐induced striatal serotonin reductions. Synapse 56:84–93, 2005. © 2005 Wiley‐Liss, Inc.
Molecular chaperone, HSP60, and cytochrome P450 2E1 co‐expression in dilated cardiomyopathy
Authors: Sidorik L. , Kyyamova R. , Bobyk V. , Kapustian L. , Rozhko O. , Vigontina O. , Ryabenko D. , Danko I. , Maksymchuk O. , Kovalenko V.N. , Filonenko V.V. , Chaschin N.A.
Published: February 2005

Physiological stresses (heat, hemodynamics, genetic mutations, oxidative injury and myocardial ischemia) produce pathological states in which protein damage and misfolded protein structures are a common denominator. The specialized proteins family of antistress proteins—molecular chaperons (HSPs)—are responsible for correct protein folding, dissociating protein aggregates and transport of newly synthesized polypeptides to the target organelles for final packaging, degradation or repair. They are inducible at different cell processes such as cell division, apoptosis, signal transduction, cell differentiation and hormonal stimulation. HSPs are involved in numerous diseases including cardiovascular pathologies, revealing changes of expression and cell localization.

We studied the possible changes in expression level of abundant mitochondrial chaperon Hsp60 and main human cytochrome P450 monooxygenase (2E1 isoform) at dilated cardiomyopathy (DCM) progression at the end stage of heart failure using Western blot analysis. The ischemic and normal humans' hearts were studied as control samples.

We observed the decrease of Hsp60 level in cytoplasmic fraction of DCM‐ and ischemia‐affected hearts' left ventricular and significant increase of Hsp60 in mitochondrial fractions of all hearts investigated. At the same time we detected the increase of P450 2E1 expression level in ischemic and dilated hearts' cytoplasmic fractions in comparison with normal myocardium and no detectable changes in microsomal fractions of hearts investigated which could be linked with increased level of oxidative injury for DCM heart muscle.

In addition, all the changes described are accompanied by significant decrease of ATPase activity of myosin purified from DCM‐affected heart in comparison with normal and ischemic myocardia as well.

The data obtained allow us to propose a working hypothesis of functional link between antistress (HSPs) and antioxidative (cytochromes) systems at DCM progression.
A reassessment of the inhibitory capacity of human FKBP38 on calcineurin
Authors: Weiwad Matthias , Edlich Frank , Erdmann Frank , Jarczowski Franziska , Kilka Susann , Dorn Madlen , Pechstein Arndt , Fischer Gunter
Published: February 2005

The microbial peptidomacrolide FK506 affects many eukaryotic developmental and cell signaling programs via calcineurin inhibition. Prior formation of a complex between FK506 and intracellular FK506‐binding proteins (FKBPs) is the precondition for the interaction with calcineurin. A puzzling difference has emerged between the mammalian multidomain protein hFKBP38 and other FKBPs. It was shown that hFKBP38 not only binds to calcineurin but also inhibits the protein phosphatase activity of calcineurin on its own [Shirane, M. and Nakayama, K.I. (2003) Nature Cell Biol. 5, 28–37]. Inherent calcineurin inhibition by hFKBP38 would completely eliminate the need for FK506 in controlling many signal transduction pathways. To address this issue, we have characterized the functional and physical interactions between calcineurin and hFKBP38. A recombinant hFKBP38 variant and endogenous hFKBP38 were tested both in vitro and in vivo. The proteins neither directly inhibited calcineurin activity nor affected NFAT reporter gene activity in SH‐SY5Y and Jurkat cells. In addition, a direct physical interaction between calcineurin and hFKBP38 was not detected in co‐immunoprecipitation experiments. However, hFKBP38 indirectly affected the subcellular distribution of calcineurin by interaction with typical calcineurin ligands, as exemplified by the anti‐apoptotic protein Bcl‐2. Our data suggest that hFKBP38 cannot substitute for the FKBP/FK506 complex in signaling pathways controlled by the protein phosphatase activity of calcineurin.
In silico identification of the key components and steps in IFN‐γ induced JAK‐STAT signaling pathway
Authors: Zi Zhike , Cho Kwang-Hyun , Sung Myong-Hee , Xia Xuefeng , Zheng Jiashun , Sun Zhirong
Published: February 2005

Systems biology efforts are increasingly adopting quantitative, mechanistic modeling to study cellular signal transduction pathways and other networks. However, it is uncertain whether the particular set of kinetic parameter values of the model closely approximates the corresponding biological system. We propose that the parameters be assigned statistical distributions that reflect the degree of uncertainty for a comprehensive simulation analysis. From this analysis, we globally identify the key components and steps in signal transduction networks at a systems level. We investigated a recent mathematical model of interferon gamma induced Janus kinase‐signal transducers and activators of transcription (JAK‐STAT) signaling pathway by applying multi‐parametric sensitivity analysis that is based on simultaneous variation of the parameter values. We find that suppressor of cytokine signaling‐1, nuclear phosphatases, cytoplasmic STAT1, and the corresponding reaction steps are sensitive perturbation points of this pathway.
Enhanced plasminogen activation by staphylokinase in the presence of streptokinase β/βγ domains: Plasminogen kringles play a role
Authors: Dahiya Monika , Rajamohan G. , Dikshit Kanak L.
Published: February 2005

Presence of isolated β or βγ domains of streptokinase (SK) increased the catalytic activity of staphylokinase (SAK)–plasmin (Pm) complex up to 60%. In contrast, fusion of SK β or βγ domains with the C‐terminal end of SAK drastically reduced the catalytic activity of the activator complex. The enhancement effect mediated by β or βγ domain on Pg activator activity of SAK–Pm complex was reduced greatly (45%) in the presence of isolated kringles of Pg, whereas, kringles did not change cofactor activity of SAK fusion proteins (carrying β or βγ domains) significantly. When catalytic activity of SAK–microPm (catalytic domain of Pm lacking kringle domains) complex was examined in the presence of isolated β and βγ domains, no enhancement effect on Pg activation was observed, whereas, enzyme complex formed between microplasmin and SAK fusion proteins (SAKβ and SAKβγ) displayed 50–70% reduction in their catalytic activity. The present study, thus, suggests that the exogenously present β and βγ interact with Pg/Pm via kringle domains and elevate catalytic activity of SAK–Pm activator complex resulting in enhanced substrate Pg activation. Fusion of β or βγ domains with SAK might alter these intermolecular interactions resulting in attenuated functional activity of SAK.
The novel angiotensin II type 1 receptor (AT1R)‐associated protein ATRAP downregulates AT1R and ameliorates cardiomyocyte hypertrophy
Authors: Tanaka Yutaka , Tamura Kouichi , Koide Yuichi , Sakai Masashi , Tsurumi Yuko , Noda Yoshihiro , Umemura Masanari , Ishigami Tomoaki , Uchino Kazuaki , Kimura Kazuo , Horiuchi Masatsugu , Umemura Satoshi
Published: February 2005

Activation of angiotensin II (Ang II) type 1 receptor (AT1R) signaling is reported to play an important role in cardiac hypertrophy. We previously cloned a novel molecule interacting with the AT1R, which we named ATRAP (for Ang II type 1 receptor‐associated protein). Here, we report that overexpression of ATRAP significantly decreases the number of AT1R on the surface of cardiomyocytes, and also decreases the degree of p38 mitogen‐activated protein kinase phosphorylation, the activity of the c‐fos promoter and protein synthesis upon Ang II treatment. These results indicate that ATRAP significantly promotes downregulation of the AT1R and further attenuates certain Ang II‐mediated hypertrophic responses in cardiomyocytes.
Downregulated mRNA expression of ASPP and the hypermethylation of the 5′‐untranslated region in cancer cell lines retaining wild‐type p53
Authors: Liu Ze-Jun , Lu Xin , Zhang Yun , Zhong Shan , Gu Shou-Zhi , Zhang Xiao-Bing , Yang Xin , Xin Hai-Ming
Published: February 2005

The p53 protein is one of the best‐known tumour suppressors. Recently discovered ASPP1 and ASPP2 are specific activators of p53. To understand, if apoptosis‐stimulating protein of p53 (ASPP) inactivation offers a selective advantage to tumors that have wild‐type p53, we measured the mRNA expression of ASPP1 and ASPP2 in tumor cell lines retaining wide‐type p53. In addition, the CpG island methylation status of ASPP1 gene and ASPP2 gene in the 5′‐untranslated region was also investigated in order to understand the possible cause of abnormal expression of ASPP1 and ASPP2 in the tumor cell lines retaining wide‐type p53. The data showed that mRNA expression of ASPP1 and ASPP2 is downregulated and CpG island tested is hypermethylated. These results indicated that ASPP CpG island aberrant methylation could be one molecular and genetic alteration in wild‐type p53 tumours.
Inhibition of the angiogenesis by the MCP‐1 (monocyte chemoattractant protein‐1) binding peptide
Authors: Kim Mee Young , Byeon Cheol Woo , Hong Kyung Hee , Han Ki Hoon , Jeong Sunjoo
Published: February 2005

The CC chemokine, monocyte chemoattractant protein‐1 (MCP‐1), plays a crucial role in the initiation of atherosclerosis and has direct effects that promote angiogenesis. To develop a specific inhibitor for MCP‐1‐induced angiogenesis, we performed in vitro selection employing phage display random peptide libraries. Most of the selected peptides were found to be homologous to the second extracellular loops of CCR2 and CCR3. We synthesized the peptide encoding the homologous sequences of the receptors and tested its effect on the MCP‐1 induced angiogenesis. Surface plasmon resonance measurements demonstrated specific binding of the peptide to MCP‐1 but not to the other homologous protein, MCP‐3. Flow cytometry revealed that the peptide inhibited the MCP‐1 binding to THP‐1 monocytes. Moreover, CAM and rat aortic ring assays showed that the peptide inhibited MCP‐1 induced angiogenesis. Our observations indicate that the MCP‐1‐binding peptide exerts its anti‐angiogenic effect by interfering with the interaction between MCP‐1 and its receptor.
The effect of calcium ions on subcellular localization of aldolase–FBPase complex in skeletal muscle
Authors: Mamczur Piotr , Rakus Dariusz , Gizak Agnieszka , Dus Danuta , Dzugaj Andrzej
Published: February 2005

In skeletal muscles, FBPase–aldolase complex is located on α‐actinin of the Z‐line. In the present paper, we show evidence that stability of the complex is regulated by calcium ions. Real time interaction analysis, confocal microscopy and the protein exchange method have revealed that elevated calcium concentration decreases association constant of FBPase–aldolase and FBPase‐α‐actinin complex, causes fast dissociation of FBPase from the Z‐line and slow accumulation of aldolase within the I‐band and M‐line. Therefore, the release of Ca2+ during muscle contraction might result, simultaneously, in the inhibition of glyconeogenesis and in the acceleration of glycolysis.
Space in systems biology of signaling pathways – towards intracellular molecular crowding in silico
Authors: Takahashi Kouichi , Arjunan Satya Nanda Vel , Tomita Masaru
Published: February 2005

How cells utilize intracellular spatial features to optimize their signaling characteristics is still not clearly understood. The physical distance between the cell‐surface receptor and the gene expression machinery, fast reactions, and slow protein diffusion coefficients are some of the properties that contribute to their intricacy. This article reviews computational frameworks that can help biologists to elucidate the implications of space in signaling pathways. We argue that intracellular macromolecular crowding is an important modeling issue, and describe how recent simulation methods can reproduce this phenomenon in either implicit, semi‐explicit or fully explicit representation.