bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substituent effects on the polycondensation of quinones with aromatic amines to form poly(quinone imine)s
Authors: Dibattista James , Schmidt Brian M. , Buyle Padias Anne , Hall H. K. 
Published: August 2002

AbstractThe effect of alkyl groups on the polycondensation of aromatic diamines and quinones to form poly(quinone imine)s was investigated. Models were synthesized under standard conditions: 1 equiv of quinone was reacted with 2 equiv of aniline in the presence of titanium tetrachloride and 1,4‐diazabicyclo[2.2.2]octane. Only modest yields of diimines were obtained when alkyl substituents were introduced. Likewise, alkyl substituents were harmful in the polycondensation of both anthraquinones and benzoquinones with aromatic diamines. As for fluorine substituents, model reactions with either 1,5‐difluoroanthraquinone or 1,4‐difluoroanthraquinone with aniline proceeded in high yields. These model compounds for aromatic poly(quinone imine)s were characterized with 1H NMR spectroscopy, 19F NMR spectroscopy, variable‐temperature 1H NMR spectroscopy, and X‐ray crystal structure determination. Polymers of the difluoroanthraquinones with aromatic diamines were obtained in high yields, although not in high molecular weights, and no stereocontrol was found. Both p‐benzoquinones and anthraquinones were used as monomers in these polymerizations, and a fundamental difference in reactivity was observed. With the former, the polymerization behaved as a classical polycondensation and demanded exact reagent equivalence. With the anthraquinones, however, the polymerization proceeded by a condensation chain polymerization and was much more forgiving. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 43–54, 2002
Synthesis and characterization of soluble polyimides derived from 2,2′‐Bis(3,4‐dicarboxyphenoxy)‐9,9′‐spirobifluorene dianhydride
Authors: Reddy D. Sahadeva , Shu Ching‐Fong , Wu Fang‐Iy 
Published: August 2002

AbstractThe synthesis of aromatic poly(ether imide)s containing spirobifluorene units in the polymer backbone is described. 2,2′‐Bis(3,4‐dicarboxyphenoxy)‐9,9′‐spirobifluorene dianhydride, which was used as a new monomer, was synthesized with 2,2′‐dihydroxy‐9,9′‐spirobifluorene as the starting material. In the spiro‐segment, the rings of the connected bifluorene were orthogonally arranged. This bis(ether anhydride) monomer was employed in reactions with a variety of aromatic diamines to furnish poly(ether imide)s, involving an initial ring‐opening polycondensation and subsequent chemically induced cyclodehydration. Excellent solubility in common organic solvents at room temperature, good optical transparency, and high thermal stability are the prominent characteristic features of these new polymers, which can be attributed to the presence of spiro‐fused orthogonal bifluorene segments along the polymer chain. The glass‐transition temperatures of the polyimides were 240–293 °C, and the 5% weight‐loss temperatures were greater than 500 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 262–268, 2002
Polyesters by lipase‐catalyzed polycondensation of unsaturated and epoxidized long‐chain α,ω‐dicarboxylic acid methyl esters with diols
Authors: Warwel Siegfried , Demes Christoph , Steinke Georg 
Published: August 2002

AbstractLong‐chain, symmetrically unsaturated α,ω‐dicarboxylic acid methyl esters (C18, C20, C26) were obtained by the catalytic metathetical condensation of 9‐decenoic, 10‐undecenoic, and 13‐tetradecenoic acid methyl esters, respectively, with the homogeneous Grubbs catalyst bis(tricyclohexyl phosphine) benzylidene ruthenium dichloride dissolved in methylene chloride. The dicarboxylic acid esters were epoxidized chemoenzymatically with H2O2/methyl acetate with Novozym 435®, an immobilized lipase B from Candida antarctica. Polyesters from symmetrically unsaturated or epoxidized α,ω‐dicarboxylic acid methyl esters with 1,3‐propanediol or 1,4‐butanediol, respectively, were achieved by enzymatic polycondensation with the same biocatalyst applied. With 1,3‐propanediol as a substrate, the linear unsaturated and epoxidized polyesters had molecular weights of 1950–3300 g/mol and melting points of 47–75 °C, whereas with 1,4‐butanediol as a substrate, the resulting polyesters showed higher molecular weights, 7900–11,600 g/mol, with similar melting points of 55–74 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1601–1609, 2001
Molecular dynamics in nanostructured polyimide–silica hybrid materials and their thermal stability
Authors: Bershtein V. A. , Egorova L. M. , Yakushev P. N. , Pissis P. , Sysel P. , Brozova L. 
Published: August 2002

AbstractMolecular motion and thermal stability in two series of nanophase‐separated polyimide–silica (PI–SiO2) hybrid materials with chemically bound components were studied. The hybrids were synthesized from p‐aminophenyltrimethoxysilane‐terminated poly(amic acid)s as PI precursors and tetramethoxysilane as a silica precursor via a sol–gel process. The hybrids differed in their PI chemical structure and chain length (number‐average molecular weight = 5.000, 7.500, or 10.000) and in their SiO2 content, which ranged from 0 to 50 wt %. Differential scanning calorimetry, laser‐interferometric creep rate spectroscopy, and thermally stimulated depolarization current techniques were used for studying the dynamics from 100 to 650 K and from 10−3 to 10−2 Hz. Comparative thermogravimetric measurements were also carried out from 300 to 900 K. Silica nano‐ or submicrodomains that formed affected PI dynamics in two opposite directions. Because of the loosening of the molecular packing of PI chains confined to nanometer‐scale spaces between silica constraints, an enhancement of small‐scale motion, mostly at temperatures below the β‐relaxation region, occurred. However, a partial or total suppression of segmental motion could be observed above the β‐relaxation temperature, drastically so for the shortest PI chains at elevated silica contents and within or close to the glass‐transition range, because of the covalent anchoring of chain ends to silica domains. Large changes in thermal stability, including a 2.5‐fold increase in the apparent activation energy of degradation, were observed in the hybrids studied. A greater than 100 °C rise in long‐term thermal stability could be predicted for some hybrids with respect to pure PI. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1056–1069, 2002
Miscible blends of nitro‐substituted polybenzimidazole and polyetherimide
Authors: Cho Junhan , Park Min Su , Choi Jin Hyun , Ji Byung Chul , Han Sung Soo , Lyoo Won Seok 
Published: August 2002

AbstractA novel blend system was prepared by blending organosoluble nitro‐substituted polybenzimidazole (NO2‐PBI) and polyetherimide (PEI) in a cosolvent at a moderate condition. It was shown that the NO2‐PBI/PEI blends not only possess tractable processability owing to the enhanced solubility of NO2‐PBI but also retain the desirable features of unmodified PBI/PEI blends. Apparent miscibility in the blends was observed and attributed to hydrogen‐bonding interactions between NH groups in NO2‐PBI and carbonyl groups in PEI. It was revealed that the NO2‐PBI/PEI blends phase‐separate upon heating above the glass‐transition temperatures. The observed mixing of NO2‐PBI and PEI in a molecular level, although sustainable only in the glassy region, was shown to lend synergy effects to the physical properties of the blends. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1778–1783, 2001
‘Dividing the desolation’: clients views on the benefits of a cancer counselling service
Authors: Boulton Mary , Boudioni Markella , Mossman Jean , Moynihan Clare , Leydon Geraldine , Ramirez Amanda 
Published: August 2002

AbstractThis paper describes clients' accounts of the benefits they derived from a short course of cancer counselling provided within a humanist framework. Three hundred and two clients who had attended at least one session of a short course of cancer counselling received an evaluation form, which incorporated both fixed‐choice and open‐ended questions. One hundred and forty two (47%) clients returned evaluation forms; those who had attended more sessions were significantly more likely to do so. Quantitative data were analysed using SPSS (Statistical Package for the Social Sciences) for Windows and qualitative data using a thematic approach. Almost all clients indicated that they felt they had benefited from counselling. Analysis of the open‐ended questions identified nine main benefits of counselling and four key avenues or processes through which clients derived these benefits. Overall, counselling was seen as helping them to work through powerful thoughts and feelings and so to come to terms with cancer and to regain a sense of control in their lives. The benefits of a short course of counselling which clients identified reflect the aims of humanistic counselling which are not well captured by psychiatric assessments or most standard research instruments. In evaluating cancer counselling services, assessments which include these client‐defined outcomes may provide a more sensitive way of gauging the value of counselling to a non‐clinic population. Copyright © 2001 John Wiley & Sons, Ltd.
Who wants second‐line, palliative chemotherapy?
Authors: Balmer Claire E. , Thomas Peter , Osborne Richard J. 
Published: August 2002

AbstractThis paper reports on a study designed to measure the value attached to second‐line, palliative chemotherapy by people with advanced cancer, compared with the value healthy people assume they would attach if they had cancer and to assess reasons for accepting or declining treatment. Subjects comprised 92 people with cancer, 76 healthy control subjects, 60 medical oncologists, 128 clinical oncologists, 72 palliative care physicians, 58 general practitioners and 59 qualified nurses working within oncology. Using a questionnaire presenting two typical but imaginary treatment scenarios, subjects indicated whether treatment would be acceptable to them and, if so, what minimum chance and duration of benefit would make treatment worthwhile. Demographic and social data were also collected. Patients accepted a lower chance of benefit than all other groups. Although the minimum worthwhile duration of benefit was more evenly spread, patients choosing lower time values were over‐represented. These results were consistent even when treatment involved greater toxicity. The conclusion drawn from this study is that people with advanced cancer are more willing to accept second‐line chemotherapy with a lower chance and shorter duration of benefit than others may imagine. Health care professionals must recognize this when discussing treatment options with patients. Copyright © 2001 John Wiley & Sons, Ltd.
Metal airway stent implantation in children: Follow‐up of seven children
Authors: Nicolai T. , Huber R.M. , Reiter K. , Merkenschlager A. , Hautmann H. , Mantel K. 
Published: August 2002

AbstractLong segment malacia of the trachea or main stem bronchi in children is not always suitable for surgical correction; patients may therefore remain ventilator‐dependent and/or experience severe obstructive crises. We treated 7 children (ages, 4 months to 9 years) with extreme structural central airway obstruction with stent implantations. Six were mechanically ventilated; 5 had frequent life‐threatening obstructive spells requiring deep sedation or paralysis. Diagnoses were: syndrome‐associated tracheobronchomalacia (n = 4), malignancy infiltrating the carina (n = 1), congenital tracheal stenosis (n = 1), and tracheobronchial compression by a malpositioned aorta (n = 1). Six tracheal and 13 bronchial stents were endoscopically placed. The prostheses included mesh titan (n = 5), the newer shape memory material nitinol (n = 13), and 1 Y‐shaped carina stent. Follow‐up was reported for 7 weeks to 72 months.All patients showed marked improvement of their respiratory obstruction. Six children were weaned at least temporarily from ventilation. No significant bleeding, stenosis, or perforation was observed. Seven stents were changed after up to 14 months. Three children are well and at home. In 2 children airway stabilization was successful, but they later died from causes unrelated to stent placement, and 2 children died due to generalized airway disease.Soft metal mesh airway stents can offer a therapeutic option in life‐threatening inoperable obstruction of the trachea and main stem bronchi in children. Pediatr Pulmonol. 2001; 31:289–296. © 2001 Wiley‐Liss, Inc.
Eosinophil cationic protein in infants with respiratory syncytial virus bronchiolitis: Predictive value for subsequent development of persistent wheezing
Authors: Pifferi Massimo , Ragazzo Vincenzo , Caramella Davide , Baldini Giuliano 
Published: August 2002

AbstractInfants with acute bronchiolitis during the first months of life are at increased risk of developing persistent wheezing and bronchial asthma later in life. The study of eosinophil cationic protein (ECP) suggests that eosinophil‐related inflammatory mechanisms may play a role in respiratory syncytial virus (RSV) bronchiolitis. The aim of our study was to verify whether serum ECP (s‐ECP) measurements are useful in predicting the development of persistent wheezing in children affected by RSV bronchiolitis during a 5 years follow‐up period. Forty‐eight infants were enrolled prospectively (mean age: 153.5 days). All had a clinical and radiological diagnosis of acute bronchiolitis and confirmed RSV infection. Peripheral eosinophil counts, levels of s‐ECP, and serum IgE concentrations were measured during bronchiolitis. Five years later the children were re‐evaluated in regard to their respiratory symptoms (standardized questionnaires) and atopic status (specific IgE levels).We observed significantly higher s‐ECP levels (P < 0.001) at enrollment in subjects who developed persistent wheezing compared to subjects who did not show late wheezing. Initial s‐ECP values allowed significant and correct prediction of persistent wheezing (P < 0.001). The risk to develop respiratory symptoms was 9.73 higher for infants with s‐ECP levels ≥ 8 μg/L than for those with s‐ECP levels <8 μg/L (P < 0.0001).In conclusion, our study suggests that s‐ECP levels in infants with bronchiolitis are useful in predicting the risk to develop wheezing in the subsequent 5 years. Pediatr Pulmonol. 2001; 31:419–424. © 2001 Wiley‐Liss, Inc.
Spirometry in children aged 3 to 5 years: Reliability of forced expiratory maneuvers*
Authors: Crenesse D. , Berlioz M. , Bourrier T. , Albertini M. 
Published: August 2002

AbstractThe aim of this study was to evaluate the feasibility and reproducibility of forced expiratory maneuvers during standard spirometric evaluation in preschool children. Among 570 young children attending our laboratory, we retrospectively selected 355 patients (14% 3–4‐year‐olds, 48% 4–5‐year‐olds, and 38% 5–6‐year‐olds) who carried out spirometric tests for the first time. The indications for such tests were history of asthma (70%), followed by chronic cough (20%) and other miscellaneous conditions (10%).Eighty‐eight, 175, and 92 children performed one, two, and three acceptable tests respectively. Forced expired volume in 1 sec (FEV1) and forced vital capacity (FVC) did not differ significantly between attempts in children performing either two or three attempts. Forced expiratory time (FET), i.e., the total time required for the forced expiratory maneuver, was 1.7 ± 0.1 sec (mean ± SEM), and was no greater than 1 sec in 21.3% of all tested children. Consequently, FEV1 does not appear to be well‐suited to this age group. Forced expiratory volume in 0.50 and 0.75 sec (FEV0.5, FEV0.75) were thus measured in the group of children performing three attempts (n = 92), and there was no statistical difference between attempts. In 267 children performing two or three tests, the ATS criteria of reproducing FEV1 and FVC within ≤ 0.1 L seemed to be preferable in this young population. Indeed, more than 70% of the tested children presented their two best efforts (FVC and FEV1) not varying by more than 0.1 L. Individual coefficients of variation (CV = SD/mean×100%) over three tests for FEV1 and FVC were 6.71 ± 0.53% and 6.35 ± 0.41% (mean ± SEM), respectively.These results show that forced expiratory tests are not always feasible in young children, but that 55% (196/355) of our selected population performed reliable maneuvers (at least two FVC and FEV1 reproducible within 0.1 L), provided that they were supervised by a carefully trained pediatric medical staff. Pediatr Pulmonol. 2001; 32:56–61. © 2001 Wiley‐Liss, Inc.
RETRACTED: Stat3 enhances the growth of LNCaP human prostate cancer cells in intact and castrated male nude mice
Authors: DeMiguel Fernando , Lee Soo Ok , Lou Wei , Xiao Xiao , Pflug Beth R. , Nelson Joel B. , Gao Allen C. 
Published: August 2002

AbstractBACKGROUNDProstate cancer frequently progresses from an initial androgen dependence to androgen independence, rendering the only effective androgen ablation therapy useless. The mechanism underlying the androgen‐independent progression is unknown. Stat3, a member of the family of signal transducers and activators of transcription, is activated in numerous cancers, including prostate. This study is to investigate the role of Stat3 activation in the growth of prostate cancer cells.METHODSA constitutively active Stat3 was ectopically expressed in androgen‐sensitive LNCaP prostate cancer cells and resulting stable clones expressing activated Stat3 were isolated. The effect of Stat3 activation on LNCaP cell growth in response to androgen in vitro and in vivo was examined.RESULTSWe show that the levels of activated Stat3 are associated with the progression of androgen‐independent prostate cancer. Activation of Stat3 in androgen‐sensitive LNCaP prostate cancer cells results in enhancement of tumor growth in both intact and castrated male nude mice and enhances androgen receptor‐mediated prostate specific antigen expression.CONCLUSIONSThese findings demonstrate that intracellular signaling mediated by Stat3 can enhance the growth of androgen‐sensitive human LNCaP prostate cancer cells in both intact and castrated male nude mice. Prostate 52:123–129, 2002. © 2002 Wiley‐Liss, Inc.
In vitro dorsal root ganglia and human prostate cell line interaction: Redefining perineural invasion in prostate cancer
Authors: Ayala Gustavo E. , Wheeler Thomas M. , Shine H. David , Schmelz Monika , Frolov Ana , Chakraborty Subhendu , Rowley David 
Published: August 2002

AbstractBackgroundLittle is understood regarding mechanisms of perineural invasion in prostate cancer progression. We present a novel model system and data that indicate perineural invasion is an active, specific, and reciprocal interaction between nerves and prostate cancer cells.MethodsMouse dorsal root ganglia (DRG) and human prostate cancer cells (Du‐145, LNCaP, PC3) and stromal cells (HTS‐40F) were co‐cultured in Matrigel matrix. Control cultures consisted of prostate cancer and stromal cells only and DRG only. Neurite outgrowth, cell colony growth, neurite‐colony contact, and retrograde extension were quantitated with dark phase microscopy and image analysis (Optimas 6.1).ResultsDirectional outgrowth of neurites was observed projecting into DU‐145 colonies within 24 hr of co‐culture. Cultures with the greatest number of DU‐145 cells recruited significantly more neurites and established contact earlier, indicating this process was cell‐seeding density dependent. Once neurite/DU‐145 cell contact was established neurite growth diminished, suggesting an active neurite recruitment by DU‐145 cells. Subsequent to neurite contact, DU‐145 cells migrated along neurites in a retrograde fashion into the nerve/ganglion of origin (retrograde extension) establishing perineural invasion. In addition to perineural invasion, DU‐145 colony growth was elevated in DRG co‐cultures relative to DU‐145‐only control cell cultures. Similarly, the degree of neurite outgrowth was elevated in DRG‐cell co‐cultures relative to DRG‐only control cultures. The same observations were made with LNCaP and PC3 cells, but interactions between stromal cells and nerves were not found.ConclusionsThis study shows the utility of the prostate cancer/DRG in vitro system to study specific mechanism of prostate cancer cell‐nerve interaction. Morever, these data suggest that perineural invasion mechanisms involve active and reciprocal interactions between carcinoma cells and adjacent nerve/ganglions in prostate cancer progression. Prostate 49:213–223, 2001. © 2001 Wiley‐Liss, Inc.
Combining mutations in HIV‐1 protease to understand mechanisms of resistance
Authors: Mahalingam Bhuvaneshwari , Boross Peter , Wang Yuan‐Fang , Louis John M. , Fischer Christopher C. , Tozser Jozsef , Harrison Robert W. , Weber Irene T. 
Published: August 2002

AbstractHIV‐1 develops resistance to protease inhibitors predominantly by selecting mutations in the protease gene. Studies of resistant mutants of HIV‐1 protease with single amino acid substitutions have shown a range of independent effects on specificity, inhibition, and stability. Four double mutants, K45I/L90M, K45I/V82S, D30N/V82S, and N88D/L90M were selected for analysis on the basis of observations of increased or decreased stability or enzymatic activity for the respective single mutants. The double mutants were assayed for catalysis, inhibition, and stability. Crystal structures were analyzed for the double mutants at resolutions of 2.2–1.2 Å to determine the associated molecular changes. Sequence‐dependent changes in protease‐inhibitor interactions were observed in the crystal structures. Mutations D30N, K45I, and V82S showed altered interactions with inhibitor residues at P2/P2′, P3/P3′/P4/P4′, and P1/P1′, respectively. One of the conformations of Met90 in K45I/L90M has an unfavorably close contact with the carbonyl oxygen of Asp25, as observed previously in the L90M single mutant. The observed catalytic efficiency and inhibition for the double mutants depended on the specific substrate or inhibitor. In particular, large variation in cleavage of p6pol‐PR substrate was observed, which is likely to result in defects in the maturation of the protease from the Gag‐Pol precursor and hence viral replication. Three of the double mutants showed values for stability that were intermediate between the values observed for the respective single mutants. D30N/V82S mutant showed lower stability than either of the two individual mutations, which is possibly due to concerted changes in the central P2‐P2′ and S2‐S2′ sites. The complex effects of combining mutations are discussed. Proteins 2002;48:107–116. © 2002 Wiley‐Liss, Inc.