bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proteome analysis of the purine stimulon from Lactococcus lactis
Authors: Beyer Natascha H. , Roepstorff Peter , Hammer Karin , Kilstrup Mogens 
Published: May 2003

AbstractA comparative expression proteome analysis was carried out by analyzing differential expression patterns of pulse‐labelled proteins on two‐dimensional gels under standard conditions and during purine nucleotide starvation, followed by mass spectrometric identification of regulated proteins. Based upon the expression patterns, three stimulons could be identified in Lactococcus lactis subsp. cremoris. The Psu proteins (purine starvation up‐regulated) had increased synthesis during purine depletion in a purine auxotroph. Among these proteins were enzymes of the purine biosynthesis pathways (PurE, PurS, PurM, PurL), and enzymes involved in the generation of C1 units (GlyA, Fhs). C1 units are primarily required for purine biosynthesis. Upon analysis of the nucleotide sequence preceding the structural genes for these proteins in the L. lactis IL1403 genome sequence showed that all contained PurBox‐Pribnov box structures resembling the PurR activated promoters for the purDEK and purCSQLF operons. Most, and possibly all members of the Psu stimulon are thus members of the PurR regulon. Five Psu proteins could not be identified. The second stimulon, the Psd stimulon (purine starvation decreased), whose members are down‐regulated during purine depletion, contained proteins related to protein synthesis (PpsB, EF‐TS, trigger factor), or to GTPases (FtsZ, EF‐TS); or are involved in energy metabolism (GapB, CcpA). No common regulatory elements could be found for members of this stimulon. Two Psd proteins escaped identification. The last, Dcu (decoynine up‐regulated), stimulon contained proteins whose synthesis escaped the severe general depression during inhibition of the GMP synthetase by decoynine. This regulon was comprised of mostly glycolytic enzymes (fructose bisphosphate aldolase, enolase, pyruvate kinase) and translation elongation factors (GTPases: EF‐TU, EF‐G). Two Dcu proteins could not be identified. Out of 28 proteins subjected to mass spectrometry, 19 could be readily identified despite the fact that only the genome sequence of a strain of L. lactis subsp. lactis was available. The two subspecies share about 85% sequence identity, comparable to the genetic distance between Escherichia coli and Salmonella typhimurium. A success rate of 68% indicates that it may be feasible to perform proteomics based upon genomic sequences of relatives outside the genus.
Adsorption of bovine serum albumin onto poly(methyl methacrylate) stereocomplex films with a molecularly regulated nanostructure
Authors: Hamada Ken‐Ichi , Yamashita Keiko , Serizawa Takeshi , Kitayama Tatsuki , Akashi Mitsuru 
Published: May 2003

AbstractStereoregular poly(methyl methacrylate)s (PMMAs) were stepwise assembled on a quartz crystal microbalance (QCM) substrate after the immersion of the QCM into alternating acetonitrile solutions at ambient temperature. A quantitative QCM analysis at each step showed stereocomplex formation on the substrate surface. The adsorption of bovine serum albumin (BSA) onto stereocomplex films with a molecularly regulated nanostructure was analyzed quantitatively. The adsorption constant and the maximum adsorption amount, calculated by the assumption of Langmuir‐type adsorption, showed that BSA adsorbed with a relatively weak interaction onto the stereocomplex films. The BSA adsorption onto the stereocomplex films occurred in an end‐on manner, with a smaller adsorption constant than for that onto individual spin‐coated films. The amount of BSA adsorbed was significantly affected by the molecular weight of syndiotactic PMMA. Attenuated total reflection spectra indicated that BSA adsorbed onto the films with or without denaturing. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1807–1812, 2003
Synthesis of a novel hybrid liquid‐crystalline rod–coil diblock copolymer
Authors: Yi Yi , Wan Xinhua , Fan Xinghe , Dong Rong , Zhou Qifeng 
Published: May 2003

AbstractA series of novel rod–coil diblock copolymers on the basis of mesogen‐jacketed liquid‐crystalline polymer were successfully prepared by atom transfer radical polymerization from the flexible polydimethylsiloxane (PDMS) macroinitiator. The hybrid diblock copolymers, poly{2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene}‐block‐polydimethylsiloxane, had number‐average molecular weights (Mn's) ranging from 9500 to 30,900 and relatively narrow polydispersities (≤1.34). The polymerization proceeded with first‐order kinetics. Data from differential scanning calorimetry validated the microphase separation of the diblock copolymers. All block copolymers exhibited thermotropic liquid‐crystalline behavior except for the one withMnbeing 9500. Four liquid‐crystalline diblock copolymers with PDMS weight fractions of more than 18% had two distinctive glass‐transition temperatures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1799–1806, 2003
Further evidence for the inseparability of the theoretical enthalpic terminal and penultimate unit effects in the radical copolymerization of styrene with acrylonitrile
Authors: Kaim Andrzej , Cieplak Piotr 
Published: May 2003

AbstractThe theoretical enthalpies of propagation reactions at 0 K without zero‐point vibrational energy corrections according to terminal and penultimate models of the radical copolymerization of styrene with acrylonitrile are reported from molecular orbital calculations at the following levels of theory and basis sets: HF/6‐31G(d); B3‐LYP/6‐31G(d); B3‐LYP/6‐311G(d,p) and B3‐LYP/6‐311+G(3df)//6‐311G(d,p). Both the enthalpic terminal and penultimate unit effects, determined according to the theoretical thermochemistry, depend on the level of theory and basis set used for the molecular orbital calculations. The best performing B3LYP/6‐311+G(3df)//B3LYP/6‐311G(d,p) procedure gives theoretical enthalpies for the addition of styrene and acrylonitrile to CH that differ from experimental values by 0.6 and 1.6 kcal mol−1, respectively. An analysis of the results obtained here leads to the conclusion that at least for the styrene–acrylonitrile monomer system, that is, a monomer system known as one of the few systems that do not conform to terminal model composition and microstructure equations, the enthalpic terminal unit effects seem to depend on the penultimate units of the growing radical. This finding, together with the outcome from our previous work on the dependence of the penultimate effects on the terminal units in a growing macroradical, indicates the inseparability of the enthalpic terminal (implicit) and explicit penultimate unit effects on the radical copolymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1778–1787, 2003
Preparation of a graded‐index polymeric preform by swollen bulk polymerization
Authors: Zhen Zhen , Li Xiao‐Dong , Wang Xin‐Qiu , Huang Yong , Liu Xin‐Hou 
Published: May 2003

AbstractA swollen bulk polymerization approach for the preparation of a preform for manufacturing graded‐index plastic optical fibers was examined. The preform prepared by the proposed approach was transparent and bubble‐free and had a parabolic profile of the refractive index, with the highest refractive index at the center of the rod. The influences of the polymerization temperature and the type of dopant on the properties of the prepared preform were discussed. A higher temperature resulted in a steeper parabolic profile of the refractive index for the formed preform, and a lower temperature resulted in a higher refractive index near the core‐cladding region of the preform. The refractive‐index profiles of the preform were affected by the addition of the different types of dopants used. The concentration distribution of the dopant in the preform correlated to the refractive‐index distribution. In a comparison of bromobenzene (BB) and 1,2,4‐trichlorobenzene (TB) as dopants, it was observed that BB distributions along the profile were more uniform than TB distributions, and a dopant with a larger molecular volume was more concentrated in the core center. It was concluded that the refractive‐index distribution of the graded‐index preform could be controlled by the both temperature and the addition of different types of dopants during the swollen bulk polymerization process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1813–1818, 2003
Elementary reaction analysis of the radical polymerization of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups
Authors: Sato Tsuneyuki , Hashimoto Masahiko , Seno Makiko , Hirano Tomohiro 
Published: May 2003

AbstractThe polymerizations of α‐ethyl β‐N‐(α′‐methylbenzyl)itaconamates carrying (RS)‐ and (S)‐α‐methylbenzylaminocarbonyl groups (RS‐EMBI and S‐EMBI) with dimethyl 2,2′‐azobisisobutyrate (MAIB) were studied in methanol (MeOH) and in benzene kinetically and with electron spin resonance (ESR) spectroscopy. The initial polymerization rate (Rp) at 60 °C was given by Rp = k[MAIB]0.58 ± 0.05[RS‐EMBI]2.4 ± 0.l and Rp = k[MAIB]0.61 ± 0.05[S‐EMBI]2.3 ± 0.l in MeOH and Rp = k[MAIB]0.54 ± 0.05[RS‐EMBI]1.7 ± 0.l in benzene. The rate constants of initiation (kdf), propagation (kp), and termination (kt) as elementary reactions were estimated by ESR, where kd is the rate constant of MAIB decomposition and f is the initiator efficiency. The kp values of RS‐EMBI (0.50–1.27 L/mol s) and S‐EMBI (0.42–1.32 L/mol s) in MeOH increased with increasing monomer concentrations, whereas the kt values (0.20−7.78 × 105 L/mol s for RS‐EMBI and 0.18−6.27 × 105 L/mol s for S‐EMBI) decreased with increasing monomer concentrations. Such relations of Rp with kp and kt were responsible for the unusually high dependence of Rp on the monomer concentration. The activation energies of the elementary reactions were also determined from the values of kdf, kp, and kt at different temperatures. Rp and kp of RS‐EMBI and S‐EMBI in benzene were considerably higher than those in MeOH. Rp of RS‐EMBI was somewhat higher than that of S‐EMBI in both MeOH and benzene. Such effects of the kinds of solvents and monomers on Rp were explicable in terms of the different monomer associations, as analyzed by 1H NMR. The copolymerization of RS‐EMBI with styrene was examined at 60 °C in benzene. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1819–1830, 2003
Synthesis and characterization of fluorinated poly(amide imide)s derived from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and aromatic diamines
Authors: Li Z. X. , Fan L. , Ge Z. Y. , Wu J. T. , Yang S. Y. 
Published: May 2003

AbstractA series of fluorinated poly(amide imide)s were prepared from 1,4‐bis(2′‐trifluoromethyl‐4′‐trimellitimidophenoxy)benzene and various aromatic diamines [3,3′,5,5′‐tetramethyl‐4,4′‐diaminediphenylmethane, α,α‐bis(4‐amino‐3,5‐dimethyl phenyl)‐3′‐trifluoromethylphenylmethane, 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene, 4‐(3′‐trifluoromethylphenyl)‐2,6‐bis(3′‐aminophenyl)pyridine, and 1,1‐bis(4′‐aminophenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane]. The fluorinated poly(amide imide)s, prepared by a one‐step polycondensation procedure, had good solubility both in strong aprotic solvents, such as N‐methyl‐2‐pyrrolidinone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and cyclopentanone, and in common organic solvents, such as tetrahydrofuran and m‐cresol. Strong and flexible polymer films with tensile strengths of 84–99 MPa and ultimate elongation values of 6–9% were prepared by the casting of polymer solutions onto glass substrates, followed by thermal baking. The poly(amide imide) films exhibited high thermal stability, with glass‐transition temperatures of 257–266 °C and initial thermal decomposition temperatures of greater than 540 °C. The polymer films also had good dielectric properties, with dielectric constants of 3.26–3.52 and dissipation factors of 3.0–7.7 × 10−3, and acceptable electrical insulating properties. The balance of excellent solubility and thermal stability associated with good mechanical and electrical properties made the poly(amide imide)s potential candidates for practical applications in the microelectronics industry and other related fields. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1831–1840, 2003
Clinical application of direct sputum sensitivity testing in a severe infective exacerbation of cystic fibrosis
Authors: Serisier David J. , Jones Graeme , Tuck Andrew , Connett Gary , Carroll Mary P. 
Published: May 2003

AbstractA 16‐year‐old male with cystic fibrosis (CF) was admitted to hospital with a severe infective exacerbation. Despite standard management, including conventionally selected intravenous antibiotics for Pseudomonas aeruginosa, chest physiotherapy, and institution of noninvasive ventilation (NIV) for progressive hypercapneic respiratory failure, he continued to deteriorate. Direct sputum sensitivity testing (DSST) revealed a novel combination of antibiotics that resulted in a rapid and remarkable clinical improvement. DSST is a form of “whole” sputum sensitivity testing that provides information on antibiotic synergy, and may more accurately reflect in vivo antibiotic sensitivity patterns in cystic fibrosis. Pediatr Pulmonol. 2003; 35:463–466. © 2003 Wiley‐Liss, Inc.
Expression study of three secretory proteins (prostatic secretory protein of 94 amino acids, probasin, and seminal vesicle secretion II) in dysplastic and neoplastic rat prostates
Authors: Kwong Joseph , Lui K. , Chan Peter S.F. , Ho Shuk‐Mei , Wong Y.C. , Xuan J.W. , Chan Franky L. 
Published: May 2003

AbstractBackgroundProstatic secretory protein of 94 amino acids (PSP94), probasin, and seminal vesicle secretion II (SVSII) are the three major proteins secreted by the lateral lobe of the rat prostate gland. Among these proteins, rodent PSP94 but not probasin and SVSII has a human homologue and it is also a major secretory protein of the human prostate, in addition to prostatic acid phosphatase and prostate‐specific antigen.MethodsIn this study, we examined and compared the mRNA expression of these three secretory markers in three rat models of prostate cancer including the sex steroid‐induced dysplasia (prostatic intraepithelial neoplasia or PIN) in Noble (Nb) rat model, an androgen‐independent Nb rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas (both androgen‐dependent and ‐independent) by in situ hybridization (ISH), reverse transcriptase‐polymerase chain reaction (RT‐PCR), and immunohistochemistry.ResultsThe transcripts for the three markers were highly expressed in the secretory epithelium of normal lateral prostate (LP). Their hybridization signals became reduced in the epithelial cells in the low‐grade PINs and significantly weakened or lost in the high‐grade PINs induced in the LP. Interestingly, we observed that some dysplastic cells located at the basal compartment of the PIN lesions, and nests of outpouching epithelial cells in the vicinity of PINs, expressed positive hybridization signals of three markers. In the adenocarcinoma, signals of probasin but not PSP94 and SVSII were detected. No hybridization signals were detected in both Dunning and AIT tumors. By RT‐PCR, transcripts for these proteins were still detected but significantly reduced in the Dunning tumors, whereas in the AIT tumor, only SVSII transcripts were detected. Immunohistochemistry of PSP94 also showed a reduced staining in the PIN lesions, but no immunoreactivity was seen in the rat prostatic tumors.ConclusionsThe mRNA expression of the three prostatic secretory markers were decreased in the hormone‐induced PINs and in two rat prostatic tumors, indicating that the androgen‐regulated secretory differentiation was impaired during the development of the premalignant lesion and further reduced in advanced tumors. The abnormal expression pattern of these secretory markers and androgen receptor (AR) in the basal compartment of the PIN lesions suggests that there is a population of cell types with secretory phenotype appearing in the basal cell layer during the early malignant transformation of the prostatic epithelium. Prostate 56: 81–97, 2003. © 2003 Wiley‐Liss, Inc.
Prostate cancer expression of runt‐domain transcription factor Runx2, a key regulator of osteoblast differentiation and function
Authors: Brubaker Kristen D. , Vessella Robert L. , Brown Lisha G. , Corey Eva 
Published: May 2003

AbstractBACKGROUNDProstate cancer (CaP) bone metastases express numerous proteins associated with bone cells. Specific transcription factors, including Runx2, regulate the expression of many bone‐related factors in osteoblasts. Expression of these transcription factors in CaP may be linked to the ability of CaP bone metastases to influence bone remodeling.METHODSCaP tissues and cell lines were analyzed for expression of Runx2 mRNA by RT‐PCR and in situ hybridization, and protein by immunohistochemistry, Western blotting, and electrophoretic mobility shift assays (EMSA).RESULTSRunx2 mRNA and protein were detected in CaP tissues and cell lines. A specific Runx2: OSE2 complex could be formed with PC‐3 nuclear extracts.CONCLUSIONSExpression of Runx2 in CaP may be the molecular switch that is associated with expression of various bone‐specific factors in CaP. In turn, expression of these factors can influence bone remodeling and possibly play a role in the growth and survival of CaP in bone. Prostate 56: 13–22, 2003. © 2003 Wiley‐Liss, Inc.
Agonist–PPARγ interactions: Molecular modeling study with docking approach
Authors: Xu Xiao Ying , Cheng Feng , Shen Jian Hua , Luo Xiao Min , Chen Li Li , Yue Li Duo , Du Yi , Ye Fei , Jiang Shan Hao , Zhu Da Yuan , Jiang Hua Liang , Chen Kai Xian 
Published: May 2003

AbstractDocking simulation of 18 agonists with the ligand binding pocket (LBP) of PPARγ has been performed. The binding conformations and binding affinities of these agonists were obtained by use of the flexible docking protocol FlexX. Test compound calculations indicated that FlexX can reproduce the binding conformation of the crystal structure (root mean square deviation = 1.43 Å); moreover, the predicted binding affinities correlate well with the activities of these agonists. The interaction model and pharmacophore of PPARγ agonists were derived and the difference in biologic activities of these agonists can be well explained. The PPARγ agonists must have both polar head and the hydrophobic tail, which form hydrogen bonds and hydrophobic contacts with hydrophilic and hydrophobic regions of the LBP of PPARγ, respectively. In addition, a suitable linker is also necessary. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 405–410, 2003
Population analyses that utilize projection operators
Authors: Clark Aurora E. , Davidson Ernest R. 
Published: May 2003

AbstractSeveral different methods have been explored that partition the 3‐D space of a molecule into its atomic components using Hermitian one‐electron position‐space projection operators,PA.Previously, we definedPAso that hard interatomic boundaries between atoms are observed. This idea has been extended to allow softer boundaries that have a region of overlap between atoms that can be controlled through an iterative process. Functions that determine the shape of the atomic volume are also discussed. The atomic electron populations of 17 different systems are presented as a function of these two factors. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 384–394, 2003
Theoretical study of the structure and antimicrobial activity of horminone
Authors: Nicolás Inés , Vilchis Martha , Aragón Nidia , Miranda René , Hojer Germund , Castro Miguel 
Published: May 2003

AbstractThe structural and electronic parameters of the horminone molecule, an abietan diterpene quinone, were studied by means of all‐electron calculations using Hartree–Fock and density functional theory‐based methods, as implemented in the Gaussian98 program. The 6‐31G orbital basis sets were used for the C, H, O, and Mg atoms. The results allow the identification of the negative site of horminone (HM) most favorable for its binding to the Mg2+ ion. The HM–Mg2+ complex is assumed to play a significant role in the antibacterial activity. First, it penetrates the membrane cell. Then, through its interaction with rRNA, it inhibits the protein synthesis in several types of bacteria. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 411–421, 2003
Gas‐phase geometries and energies of bis(2,2′‐bipyridine) interacting either with Cu(I) or Ag(I): Computational study
Authors: Corongiu Giorgina , Nava Paola 
Published: May 2003

AbstractWith a polarized double‐zeta basis set, we carried out MP2 and density functional theory geometry optimization of bis(2,2′‐bipyridine) interacting either with Cu(I) or Ag(I). The computed gas‐phase geometries of both Cu and Ag complexes present tetrahedral distortions around the ions. However, geometry optimization on Cu or Ag ions complexing with ammonia molecules yield perfect tetrahedral coordination and interaction energies comparable to those of the bis(2,2′‐bipyridine) complexes. Solid‐state laboratory studies on complexes of the same metal ions with substituted bis(2,2′‐bipyridine) revealed tetrahedral distortions around the ions, even stronger than those computed in the gas phase. From our analysis of the potential interaction energies we conclude that the origin of the larger distortions in the solid state result from stacking interactions. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 395–404, 2003
Interaction of hepatitis B virus with cells
Authors: Paran Nir , Cooper Arik , Shaul Yosef 
Published: May 2003

AbstractVirus infection is initiated by recognition and attachment of the virus to the cell surface. Despite the fact that this interaction determines the virus‐related pathogenesis, its molecular basis remained obscure for HBV. This process is mediated primarily by the viral envelope and the cellular receptors. HBV infection is not exceptional in this regard but its putative receptors have not been identified yet. The recent development of protocols to establish HBV susceptible cell lines and unique tools to measure HBV‐cell attachment at a single cell resolution set the stage for the study of HBV‐host cell interaction. These studies revealed that the QLDPAF epitope of the HBV surface antigen large protein (LHBsAg) plays a major role in this process. Quantitative measurements suggested the presence of a second player in this process and both act synergistically to improve cell attachment. As the step of virus‐cell attachment is potentially susceptible to specific inhibitors, understanding the molecular basis of virus‐cell attachment can be expected to have therapeutic impacts. Copyright © 2003 John Wiley & Sons, Ltd.