bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cure kinetics of the ring‐opening metathesis polymerization of dicyclopentadiene
Authors: Kessler M. R. , White S. R. 
Published: October 2002

AbstractThe cure kinetics of polydicyclopentadiene prepared by ring‐opening metathesis polymerization with three different concentrations of Grubbs' catalyst were examined with differential scanning calorimetry. The experimental data were used to test several different phenomenological kinetic models. The data were best modeled with a model‐free isoconversional method. This analysis revealed that the activation energy increased significantly for degrees of cure greater than 60%. The catalyst concentration had a large effect on the cure kinetics. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2373–2383, 2002
Novel quaternary ammonium borates as latent catalysts for epoxy–phenolic resins
Authors: Goh Yoshiyuki , Iijima Takao , Tomoi Masao 
Published: October 2002

AbstractNovel tetrabutylammonium tetrakis(substituted benzoyloxy)borate salts (1a–1d) were synthesized by the reaction of tetrabutylammonium tetraphenylborate and corresponding substituted benzoic acids. Polyaddition reactions of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐bisphenol F (44BPF) or bisphenol F (BPF‐D) with the ammonium borates were investigated as model reactions of epoxy/phenol–novolac resin systems with respect to the thermal latency and storage stability of the catalyst. The polyaddition of DGEBA/44BPF with the ammonium borates in diglyme at 150 °C for 6 h proceeded up to 84–94% conversions and gave polymers with number‐average molecular weights of 3750–5750, whereas the polyaddition at 80 °C for 6 h gave less than 9% conversions. The catalytic activity of ammonium borates 1a–1d depended on the substituent of the phenyl group of the borates, and the order of activity was 1b (p‐OMe) > 1a (H) > 1c (p‐NO2) > 1d [3,5‐(NO2)2]. The ammonium borate catalyst with the substituent that yielded lower acidity of the corresponding substituted benzoic acid tended to reveal higher activity. In comparison with tetrabutylammonium bromide (TBAB) as a conventional ammonium salt, 1a–1d revealed better thermal latency. The storage stability of DGEBA/BPF‐D with the ammonium borate catalysts in bulk at 40 °C was better than that with TBAB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2689–2701, 2002
Vinylic polymerization of norbornene by neutral nickel(II)‐based catalysts
Authors: Li Xiao‐Fang , Li Yue‐Sheng 
Published: October 2002

AbstractNeutral Ni(II) salicylaldiminato complexes activated with modified methylaluminoxane as catalysts were used for the vinylic polymerization of norbornene. Catalyst activities of up to 7.08 × 104 kgpol/(molNi · h) and viscosity‐average molecular weights of polymer up to 1.5 × 106 g/mol were observed at optimum conditions. Polynorbornenes are amorphous, soluble in organic solvents, highly stable, and show glass‐transition temperatures around 390 °C. Catalyst activity, polymer yield, and polymer molecular weight can be controlled over a wide range by the variation of the reaction parameters such as the Al/Ni ratio, monomer/catalyst ratio, monomer concentration, polymerization reaction temperature, and time. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2680–2685, 2002
Self‐assembling directed synthesis of a novel terephthalamide‐bridged ladderlike polysiloxane
Authors: Li Hui , Liu Chunqing , Guo Guangqing , Zhou Xiaoshu , Zhang Jianmin , Shen Deyan , Zhang Zhongxing , Xie Ping , Yu Shuyan , Zhang Rongben 
Published: October 2002

AbstractA novel, soluble terephthalamide‐bridged ladderlike polysiloxane (L) was synthesized successfully for the first time by stepwise coupling polymerization. The process involved the hydrogen‐bonding self‐assembly of amido groups, which resulted in the formation of a more highly ordered polymeric structure. A novel monomer, bis(3‐methyldimethoxysilylpropyl) terephthalamide (M), was prepared by a hydrosilylation reaction in the presence of dicyclopentadienyl platinum dichloride as a catalyst. The structures of the monomer (M) and the polymer (L) were characterized by Fourier transform infrared, 1H NMR, 13C NMR, 29Si NMR, mass spectrometry, X‐ray diffraction, differential scanning calorimetry, and vapor pressure osmometry. All the characterization data indicated that the synthesized polymer (L) possessed an ordered ladderlike structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3161–3170, 2002
Synthesis and characterization of poly(β‐hydroxybutyrate) and poly(ϵ‐caprolactone) copolyester by transesterification
Authors: Chen Cheng , Fei Bin , Peng Shuwen , Wu Hang , Zhuang Yugang , Chen Xuesi , Dong Lisong , Feng Zhiliu 
Published: October 2002

AbstractTo synthesize the copolyester of poly(β‐hydroxybutyrate) (PHB) and poly(ϵ‐caprolactone) (PCL), the transesterification of PHB and PCL was carried out in the liquid phase with stannous octoate as the catalyzer. The effects of reaction conditions on the transesterification, including catalyzer concentration, reaction temperature, and reaction time, were investigated. The results showed that both rising reaction temperature and increasing reaction time were advantageous to the transesterification. The sequence distribution, thermal behavior, and thermal stability of the copolyesters were investigated by 13C NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction, optical microscopy, and thermogravimetric analysis. The transesterification of PHB and PCL was confirmed to produce the block copolymers. With an increasing PCL content in the copolyesters, the thermal behavior of the copolyesters changed evidently. However, the introduction of PCL segments into PHB chains did not affect its crystalline structure. Moreover, thermal stability of the copolyesters was little improved in air as compared with that of pure PHB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1893–1903, 2002
Spinal muscular atrophy type 1: Management and outcomes
Authors: Bach John R. , Baird J. Scott , Plosky Daniel , Navado Jose , Weaver Brian 
Published: October 2002

AbstractOur objectives were to describe survival, hospitalization, speech, and outcomes related to respirator needs for spinal muscular atrophy type 1 (SMA1) patients, using noninvasive or tracheostomy ventilation. From 65 SMA patients referred to our clinic since 1996, we chose 56 SMA1 patients who developed respiratory failure before age 2 years. Patients either had tracheostomy tubes (group A), or used noninvasive ventilation and assisted coughing; a previously reported extubation protocol (group B) was used as needed.Sixteen patients underwent tracheostomy at 10.8 ± 5.0 months of age, 33 were in group B, and 7 others died without life‐support interventions. Compared to group B, group A patients had fewer hospitalizations until age 3 years, but more after age 5, and 15 of 16 lost all spontaneous breathing tolerance posttracheostomy and could not speak. One group A patient died at 16 months of age, and the others were 73.8 ± 57 months of age (the oldest was 19 years old). Two group B patients died at 6 and 13 months, respectively, whereas the other 31 were 41.8 ± 26.0 months (and up to 8.3 years) old. Three of 31 in group B required high‐span positive inspiratory pressure plus positive end‐expiratory pressure (PIP + PEEP) continuously with minimal tolerance for breathing on their own, and 4 could not communicate verbally.In conclusion, SMA type 1 children can survive beyond 2 years of age when offered tracheostomy or noninvasive respiratory support. The latter is associated with fewer hospitalizations after age 5 years, freedom from daytime ventilator use, and the ability to speak. Pediatr Pulmonol. 2002; 34:16–22. © 2002 Wiley‐Liss, Inc.
Pseudomonas aeruginosa and other predictors of mortality and morbidity in young children with cystic fibrosis
Authors: Emerson Julia , Rosenfeld Margaret , McNamara Sharon , Ramsey Bonnie , Gibson Ronald L. 
Published: October 2002

AbstractWe conducted a registry‐based study to determine prognostic indicators of 8‐year mortality and morbidity in young children with cystic fibrosis (CF). Patients ages 1–5 years from the 1990 U.S. Cystic Fibrosis Foundation (CFF) National Patient Registry served as the study cohort (N = 3,323). Registry data provided information on baseline characteristics in 1990, 8‐year mortality, and clinical outcomes in 1998.P. aeruginosa respiratory infection was found to be a major predictor of morbidity and mortality. The 8‐year risk of death was 2.6 times higher in patients who had respiratory cultures positive for P. aeruginosa in 1990 (95% confidence interval 1.6, 4.1) than in children without P. aeruginosa in their respiratory cultures. Culture‐positive patients in 1990 also had a significantly lower percent predicted forced expiratory volume in 1 sec (FEV1) and weight percentile at follow‐up, and they had an increased risk of continued P. aeruginosa respiratory infection and hospitalization for acute respiratory exacerbation in 1998. Among the other predictors of increased morbidity and mortality were lower baseline weight percentiles and number of CF‐related hospitalizations during the baseline year.These findings confirm reports from previous smaller studies of outcomes among young children with CF, and highlight the potential to decrease the morbidity and mortality of young patients with CF through early intervention. Pediatr Pulmonol. 2002; 34:91–100. © 2002 Wiley‐Liss, Inc.
Increased interleukin‐8 and monocyte chemoattractant protein‐1 concentrations in mechanically ventilated preterm infants with pulmonary hemorrhage
Authors: Baier R. John , Loggins John , Kruger Thomas E. 
Published: October 2002

AbstractPulmonary hemorrhage (PH) is a serious complication causing acute respiratory distress in the premature infant, and it is associated with significant mortality and morbidity. The role of inflammatory mediators in this condition is largely undefined. Serial tracheal aspirates (TA) were obtained at intervals from 65 mechanically ventilated infants with birth weights less than 1,250 g during the first 21 days of life. Clinically significant PH developed in 15 infants. TA concentrations of interleukin‐8 (IL‐8) and monocyte chemoattractant protein‐1 (MCP‐1) were determined by enzyme‐linked immunosorbent assay (ELISA).PH was associated with an increased risk of death, bronchopulmonary dysplasia, intraventricular hemorrhage, and prolonged need for mechanical ventilation and supplemental oxygen. TA aspirate concentrations of IL‐8 and MCP‐1 (P = 0.001, ANOVA) were significantly increased in infants with PH compared to infants who did not develop this condition. TA cytokine concentrations were also significantly increased in infants who developed bronchopulmonary dysplasia (BPD). Peak TA concentrations of IL‐8 and MCP‐1 were significantly higher in infants with poor outcome (BPD or death). TA MCP‐1 but not IL‐8 concentrations were significantly higher in infants who were oxygen‐dependent at 36 weeks postconceptional age.These data suggest a pathogenic role for IL‐8 and MCP‐1 in the development of adverse pulmonary outcome in preterm infants with clinically significant PH. Pediatr Pulmonol. 2002; 34:131–137. © 2002 Wiley‐Liss, Inc.
Association of the G289S single nucleotide polymorphism in the HSD17B3 gene with prostate cancer in Italian men
Authors: Margiotti Katia , Kim Eugene , Pearce C. Leigh , Spera Enrico , Novelli Giuseppe , Reichardt Juergen K.V. 
Published: October 2002

AbstractBACKGROUNDProstate cancer is a significant public health problem in this country. Substantial data support a plausible role for androgens in the etiology of this disease. The human HSD17B3 gene encodes the testicular (or type III) 17β‐hydroxysteroid dehydrogenase enzyme, which catalyzes testosterone biosynthesis in men.METHODSWe have investigated the G289S (glycine at codon 289 replaced by serine) polymorphism at the HSD17B3 locus as a candidate single nucleotide polymorphism (SNP) for prostate cancer risk in constitutional DNA from 103 Italian prostate cancer patients and 109 Italian disease‐free centenarians to assess the role of this SNP in susceptibility to prostate cancer.RESULTSThe G289S polymorphism confers a significant increase in risk for prostate cancer (odds ratio = 2.5; 95% confidence interval, 1.03–6.07) in our study population.CONCLUSIONOur data are consistent with a plausible role of the G289S SNP in prostate cancer susceptibility. Therefore, the HSD17B3 gene may be a plausible candidate gene for prostate cancer risk. Prostate 53: 65–68, 2002. © 2002 Wiley‐Liss, Inc.
Interaction of Hsp90 with 20S proteasome: Thermodynamic and kinetic characterization
Authors: Eleuteri A.M. , Cuccioloni M. , Bellesi J. , Lupidi G. , Fioretti E. , Angeletti M. 
Published: October 2002

AbstractThe proteasome and heat shock proteins have been found in the centrosome. The evidence of their copurification reported by several studies suggests that they form stable complex. In addition, Hsp90 is involved in the loading of proteasome‐generated antigenic peptides to the class I major histocompatibility complex. In this article, we report a detailed thermodynamic and kinetic characterization of the Hsp90‐20S proteasome interaction, using a surface plasmon resonance technique. The modulation exerted by protons in solution has been investigated, and the results have been discussed, taking into account structural motifs characterizing the binding interface between the two macromolecules. Proteins 2002;48:169–177. © 2002 Wiley‐Liss, Inc.
Crystal structure of the YjeE protein from Haemophilus influenzae: A putative Atpase involved in cell wall synthesis
Authors: Teplyakov Alexey , Obmolova Galina , Tordova Maria , Thanki Narmada , Bonander Nicklas , Eisenstein Edward , Howard Andrew J. , Gilliland Gary L. 
Published: October 2002

AbstractA hypothetical protein encoded by the gene YjeE of Haemophilus influenzae was selected as part of a structural genomics project for X‐ray analysis to assist with the functional assignment. The protein is considered essential to bacteria because the gene is present in virtually all bacterial genomes but not in those of archaea or eukaryotes. The amino acid sequence shows no homology to other proteins except for the presence of the Walker A motif G‐X‐X‐X‐X‐G‐K‐T that indicates the possibility of a nucleotide‐binding protein. The YjeE protein was cloned, expressed, and the crystal structure determined by the MAD method at 1.7‐Å resolution. The protein has a nucleotide‐binding fold with a four‐stranded parallel β‐sheet flanked by antiparallel β‐strands on each side. The topology of the β‐sheet is unique among P‐loop proteins and has features of different families of enzymes. Crystallization of YjeE in the presence of ATP and Mg2+ resulted in the structure with ADP bound in the P‐loop. The ATPase activity of YjeE was confirmed by kinetic measurements. The distribution of conserved residues suggests that the protein may work as a “molecular switch” triggered by ATP hydrolysis. The phylogenetic pattern of YjeE suggests its involvement in cell wall biosynthesis. Proteins 2002;48:220–226. © 2002 Wiley‐Liss, Inc.
Prediction of strand pairing in antiparallel and parallel β‐sheets using information theory
Authors: Steward Robert E. , Thornton Janet M. 
Published: October 2002

AbstractAn information theory approach was developed to predict the alignment of interacting antiparallel and parallel β‐strands. Information scores were derived for the preference of a residue on a β‐strand to be opposite a sequence of residues on an adjacent β‐strand. These scores were used to predict the interstrand register of interacting β‐strands from 10 alternative offset positions either side of the experimentally observed β‐sheet register. The amino acid sequence of an internal β‐strand can be correctly aligned with two β‐strands in a fixed position either side of the strand in 45% of antiparallel and 48% of parallel arrangements. For comparison, when another β‐strand from a nonhomologous protein substitutes the internal β‐strand, the same register is predicted for only 24 and 36% of antiparallel and parallel arrangements. As expected, alignment of a single fixed strand with just a second β‐strand sequence was more difficult, and gave a correct register in 31 and 37% of antiparallel and parallel β‐pairs, respectively. These scores are 10% higher than for two randomly selected β‐strand sequences. In general, prediction accuracy was not improved by information tables that distinguished hydrogen‐bonding patterns or β‐strand order. These results will contribute to predicting the arrangement of β‐strands in β‐pleated sheets and protein topology. Proteins 2002;48:178–191. © 2002 Wiley‐Liss, Inc.
Swaps in protein sequences
Authors: Fliess Amit , Motro Benny , Unger Ron 
Published: October 2002

AbstractAn important question in protein evolution is to what extent proteins may have undergone swaps (switches of domain or fragment order) during evolution. Such events might have occurred in several forms: Swaps of short fragments, swaps of structural and functional motifs, or recombination of domains in multidomain proteins. This question is important for the theoretical understanding of the evolution of proteins, and has practical implications for using swaps as a design tool in protein engineering. In order to analyze the question systematically, we conducted a large scale survey of possible swaps and permutations among all pairs of protein from the Swissport database. A swap is defined as a specific kind of sequence mutation between two proteins in which two fragments that appear in both sequences have different relative order in the two sequences. For example, aXbYc and dYeXf are defined as a swap, where X and Y represent sequence fragments that switched their order. Identifying such swaps is difficult using standard sequence comparison packages. One of the main problems in the analysis stems from the fact that many sequences contain repeats, which may be identified as false‐positive swaps. We have used two different approaches to detect pairs of proteins with swaps. The first approach is based on the predefined list of domains in Pfam. We identified all the proteins that share at least two domains and analyzed their relative order, looking for pairs in which the order of these domains was switched. We designed an algorithm to distinguish between real swaps and duplications. In the second approach, we used Blast to detect pairs of proteins that share several fragments. Then, we used an automatic procedure to select pairs that are likely to contain swaps. Those pairs were analyzed visually, using a graphical tool, to eliminate duplications. Combining these approaches, about 140 different cases of swaps in the Swissprot database were found (after eliminating multiple pairs within the same family). Some of the cases have been described in the literature, but many are novel examples. Although each new example identified may be interesting to analyze, our main conclusion is that cases of swaps are rare in protein evolution. This observation is at odds with the common view that proteins are very modular to the point that modules (e.g., domains) can be shuffled between proteins with minimal constraints. Our study suggests that sequential constraints, i.e., the relative order between domains, are highly conserved. Proteins 2002;48:377–387. © 2002 Wiley‐Liss, Inc.
Variability in the pKa of histidine side‐chains correlates with burial within proteins
Authors: Edgcomb Stephen P. , Murphy Kenneth P. 
Published: October 2002

AbstractAcidic pKas of histidines buried within the protein interior are frequently rationalized on the contradictory basis of either polar interactions within the protein or the effects of a hydrophobic environment. To examine these relationships, we surveyed the buried surface area, depth of burial, polar interactions, and crystallographic temperature factors of histidines of known pKa. It has been found that buried environments of histidines do not always result in acidic pKas. Instead, the variability of histidine pKas increases for residues where the majority of the side‐chain is buried. Because buried histidines are always found in mixed polar/apolar environments, multiple environmental contributions to pKa values must be considered. However, the quantitative relationships between heterogeneous environments and pKa values are not immediately apparent from the available data. Proteins 2002;49:1–6. © 2002 Wiley‐Liss, Inc.
Triage protein fold prediction
Authors: He Hongxian , McAllister Gregory , Smith Temple F. 
Published: October 2002

AbstractWe have constructed, in a completely automated fashion, a new structure template library for threading that represents 358 distinct SCOP folds where each model is mathematically represented as a Hidden Markov model (HMM). Because the large number of models in the library can potentially dilute the prediction measure, a new triage method for fold prediction is employed. In the first step of the triage method, the most probable structural class is predicted using a set of manually constructed, high‐level, generalized structural HMMs that represent seven general protein structural classes: all‐α, all‐β, α/β, α+β, irregular small metal‐binding, transmembrane β‐barrel, and transmembrane α‐helical. In the second step, only those fold models belonging to the determined structural class are selected for the final fold prediction. This triage method gave more predictions as well as more correct predictions compared with a simple prediction method that lacks the initial classification step. Two different schemes of assigning Bayesian model priors are presented and discussed. Proteins 2002;48:654–663. © 2002 Wiley‐Liss, Inc.
Plumieride from Allamanda cathartica as an antidermatophytic agent
Authors: Tiwari T. N. , Pandey V. B. , Dubey N. K. 
Published: October 2002

AbstractPlumieride has been isolated as an active principle of the leaves of Allamanda cathartica. It showed strong fungitoxicity against some dermatophytes causing dermatomycosis to animals and human beings. It exhibited a noncytotoxic nature against a P388 mouse leukaemia cell line. Copyright © 2002 John Wiley & Sons, Ltd.
Inductively coupled plasma mass spectrometric determination of molybdenum in urine
Authors: Minoia Claudio , Gatti Anna , Aprea Cristina , Ronchi Anna , Sciarra Gianfranco , Turci Roberta , Bettinelli Maurizio 
Published: October 2002

AbstractA method was developed for the determination of molybdenum (Mo) in human urine by direct dilution of the sample in doubly distilled water with 1% HNO3 (v/v) and inductively coupled mass spectrometry (ICP‐MS). In and Y were used as internal standards. Since 98Mo provides a higher sensitivity, it was chosen as the reference isotope. The influence of different factors, such as sample dilution, HNO3 concentration and the stability of the analyte were evaluated. The detection limit (LOD) was assessed at 0.2 µg/L Mo, while the lower limit of quantification (LOQ) was 0.6 µg/L. Recoveries ranged between 97.2 and 100.7% from solutions containing from 10 to 50 µg/L Mo. Linear calibration curves were generated from 2.1 and 52.1 µg/L with coefficients of variation (CV ) ranging from 1.62 to 3.56%. In order to establish reference values (RV) for molybdenum, the procedure presented here was used to determine Mo in the urine of a population group living in Tuscany, Italy. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of peptides using partial (no discharge) atmospheric pressure chemical ionization conditions with ion trap mass spectrometry
Authors: Cristoni Simone , Bernardi Luigi Rossi , Biunno Ida , Guidugli Federico 
Published: October 2002

AbstractA novel approach, based on the use of atmospheric pressure chemical ionization ion trap mass spectrometry (APCI‐ITMS) conditions, but without using corona discharge, was used to analyze peptides. The proposed method was applied to three standard peptides (bombesin, trityrosine and tyrosine‐glycine‐glycine) as well as peptides obtained through enzymatic digestion of two standard proteins (horse cytochrome c and horse myoglobin). Copyright © 2002 John Wiley & Sons, Ltd.