bluuebunny/crossref_metadata_2025 huggingface dataset:
Telepathology in a routine clinical environment: implementation and accuracy of diagnosis by robotic microscopy in a one‐stop breast clinic
Authors: Singh Naveena , Akbar Nuzhat , Sowter Chris , Lea Kevin G. , Wells Clive A.
Published: October 2002

The concept of using telepathology as a way of increasing the efficiency of pathologists is not new. There have been many studies attempting to evaluate the role of telepathology diagnosis, predominantly using transmission of still digital images. This study evaluates the potential value of remote diagnosis using robotic microscopy in the setting of a one‐stop breast clinic. A Zeiss Axiopath telepathology system was used. The aim was to identify deficiencies in software and theminimum specifications for the computer hardware and network capability needed for reproducible pathological diagnosis with a view to developing a system that can preclude the need for an on‐site pathologist. Forty‐seven fine needle aspiration smears were diagnosed simultaneously by a pathologist in the breast clinic and by a different pathologist operating a robotic microscope situated in the clinic in a different wing of the hospital from the pathology department. The diagnoses, the time taken for clinic and remote diagnosis, and difficulties in using the system were recorded. Absolute correlation was achieved in 80.9% of cases. There was one false‐positive diagnosis of cancer and no false negatives. The mean time taken for diagnosis per case was 2.39 min in clinic and 10.81 min by remote control robotic microscopy. However, as the pathologist did not have to leave the department, remote diagnosis was overall more economical of pathologists' time. Image quality was generally found to be good and not an obstacle to diagnosis. There were operational and technical problems that made remote diagnosis tedious and lengthy. Although at present the system is not capable of replacing an on‐site pathologist, the results were encouraging and suggest that remote control remote diagnosis has the potential to increase the efficiency of pathologists. Copyright © 2002 John Wiley & Sons, Ltd.
Gastrointestinal stem cells
Authors: Brittan Mairi , Wright Nicholas A.
Published: October 2002

Turnover of the epithelial cell lineages within the gastrointestinal tract is a constant process, occurring every 2–7 days under normal homeostasis and increasing after damage. This process is regulated by multipotent stem cells, which give rise to all gastrointestinal epithelial cell lineages and can regenerate whole intestinal crypts and gastric glands. The stem cells of the gastrointestinal tract are as yet undefined, although it is generally agreed that they are located within a ‘niche’ in the intestinal crypts and gastric glands. Studies of allophenic tetraparental chimeric mice and targeted stem cell mutations suggest that a single stem cell undergoes asymmetrical division to produce an identical daughter cell, and thus replicate itself, and a committed progenitor cell which further differentiates into an adult epithelial cell type. The discovery of stem cell plasticity in many tissues, including the ability of transplanted bone marrow to transdifferentiate into intestinal subepithelial myofibroblasts, provides a potential use of bone marrow cells to deliver therapeutic genes to damaged tissues, for example, in treatment of mesenchymal diseases in the gastrointestinal tract, such as fibrosis and Crohn's disease. Studies are beginning to identify the molecular pathways that regulate stem cell proliferation and differentiation into adult gastrointestinal cell lineages, such as the Wnt and Notch/Delta signalling pathways, and the importance of mesenchymal–epithelial interactions in normal gastrointestinal epithelium and in development and disease. Copyright © 2002 John Wiley & Sons, Ltd.
In vitro model for the study of necrosis and apoptosis in native cartilage
Authors: Grogan Shawn Patrick , Aklin Balz , Frenz Martin , Brunner Thomas , Schaffner Thomas , Mainil‐Varlet Pierre
Published: October 2002

Apoptosis plays a role in everything from early development to ageing and in a host of disease states. Studying this important process in the in vivo state is critical, to understand its varied role and to open further avenues of therapeutic intervention. The present paper presents an ex vivo bovine articular cartilage model to study apoptotic and necrotic processes following acute injury. Ex vivo bovine articular cartilage was assessed 1, 3 and 6 days following holmium : YAG laser treatment (780 mJ). Markers to visualize cell viability, caspase‐3 activity, changes in mitochondrial membrane potential and the degree of DNA fragmentation (TUNEL assay) were used alone or in various combinations. Standard histology and transmission electron microscopy (TEM) were also performed for a more comprehensive assessment. A significant progression (p < 0.05) of ethidium/caspase‐3‐positive signal depth at day 3 preceded a significant increase (p < 0.05) in TUNEL signal depth by day 6. The mitochondrial matrix marker CMXRos was shown to provide an alternative to calcein‐AM for assessing cell viability. The identification of chondrocyte apoptosis morphology by TEM was not conclusive. Nevertheless, TEM revealed that cells which were clearly necrotic also stained positively for TUNEL, thus indicating the risk of using TUNEL alone for the assessment of apoptosis. The model described here allows the rapid, spatial and temporal determination of cell viability and of apoptotic and necrotic processes in whole‐tissue specimens after acute injury, and permits study of the balance between these events. The assessment of healthy and diseased cartilage and of the effects of surgical, pharmaceutical or in vitro intervention are immediate applications of these protocols. Moreover, this model may be useful for the study of key mechanisms involved in apoptosis or for the establishment of other markers of apoptosis. Copyright © 2002 John Wiley & Sons, Ltd.
Neural stem cells
Authors: Kennea Nigel L. , Mehmet Huseyin
Published: October 2002

Neural stem cells (NSCs) have the ability to self‐renew, and are capable of differentiating into neurones, astrocytes and oligodendrocytes. Such cells have been isolated from the developing brain and more recently from the adult central nervous system. This review aims to provide an overview of the current research in this evolving area. There is now increasing knowledge of the factors controlling the division and differentiation of NSCs during normal brain development. In addition, the cues for differentiation in vitro, and the possibility of transdifferentiation are reviewed. The discovery of these cells in the adult brain has encouraged research into their role during neurogenesis in the normal mature brain and after injury. Lastly other sources of neural precursors are discussed, and the potential for stem cells to be used in cell replacement therapy for brain injury or degenerative brain diseases with a particular emphasis on cerebral ischaemia and Parkinson's disease. Copyright © 2002 John Wiley & Sons, Ltd.
Photoinitiated alternating copolymerization of vinyl ethers with chlorotrifluoroethylene
Authors: Gaboyard Manuel , Hervaud Yves , Boutevin Bernard
Published: October 2002

The photoinitiated copolymerization of chlorotrifluoroethylene (CTFE) with several vinyl ethers [ethyl vinyl ether (EVE), 2‐chloroethyl vinyl ether (CEVE), cyclohexyl vinyl ether (CHVE), 4‐hydroxybutyl vinyl ether (HBVE)] was studied. CTFE is an acceptor monomer (e ∼ 1.5) whereas vinyl ethers are donor monomers (e ∼ −1.5), and therefore their copolymerization led to alternating copolymers, as indicated by elementary analysis. The equilibrium constant (KF) of the charge‐transfer complex formation (CTC) was determined by 19F NMR spectroscopy. Under our experimental conditions, KF was low for CHVE/CTFE and HBVE/CTFE systems, 0.058 and 0.013 l mol−1 respectively. It can be assumed that the copolymerization involves the free monomers rather than propagation via the donor–acceptor complex. The alternating structure arises from the great difference in polarity between the two types of monomers. Several functional copolymers were prepared in good yield and with molecular weight close to 15 000 g mol−1.

© 2002 Society of Chemical Industry
Morphologies of polybutylacrylate/poly(styrene‐co‐methyl methacrylate) latex prepared by starved emulsion polymerization Part I. Thermodynamics equilibrium morphology
Authors: Huo Dongxia , Liu Dazhuang
Published: October 2002

Heterogeneous latexes were prepared by a semicontinuous seeded emulsion polymerization process under monomer starved conditions at 80 °C using potassium persulfate as the initiator and sodium dodecyl sulfate as the emulsifier. Poly(butyl acrylate) latexes were used as seeds. The second‐stage polymer was poly(styrene‐co‐methyl methacrylate). By varying the amounts of methyl methacrylate (MMA) in the second‐stage copolymer, the polarity of the copolymer phase could be controlled. Phase separation towards the thermodynamic equilibrium morphology was accelerated either by ageing the composite latex at 80 °C or by adding a chain‐transfer agent during polymerization. The morphologies of the latex particles were examined by transmission electron microscopy (TEM). The morphology distributions of latex particles were described by a statistical method. It was found that the latex particles displayed different equilibrium morphologies depending on the composition of the second‐stage copolymers. This series of equilibrium morphologies of [poly(butyl acrylate)/poly(styrene‐co‐methyl methacrylate)] (PBA/P(St‐co‐MMA)) system provides experimental verification for quantitative simulation. Under limiting conditions, the equilibrium morphologies of PBA/P(St‐co‐MMA) were predicted according to the minimum surface free energy change principle. The particle morphology observed by TEM was in good agreement with the predictions of the thermodynamic model. Therefore, the morphology theory for homopolymer/homopolymer composite systems was extended to homopolymer/copolymer systems.

© 2002 Society of Chemical Industry
The influence of parental and peer attachment on college students' academic achievement
Authors: Fass Michael E. , Tubman Jonathan G.
Published: October 2002

This study examined relations among attachment to parents and peers, cognitive ability, psychosocial functioning variables, and academic achievement in a multiethnic sample of college students (n = 357). A small subgroup (14.8%) of students reported low levels of attachment to both parents and peers. Significant positive correlations were documented between parent and peer attachment and several indices of psychosocial competence. Results from hierarchical multiple regression analyses revealed that indices of cognitive ability were significant predictors of college students' grade point averages, while broader measures of functioning in early adulthood (attachment, intellectual ability, self‐esteem) were significant predictors of scholastic competence. Results suggest that perceived attachment to both parents and peers is a component of wider patterns of social competence and adjustment that may function as protective or compensatory factors during key transitions in young adulthood, such as participation in college, and with its attendant demands for academic achievement. © 2002 Wiley Periodicals, Inc.
Adolescents' perceptions of their fathers' involvement: Significance to school attitudes
Authors: Flouri Eirini , Buchanan Ann , Bream Victoria
Published: October 2002

Based on data from 2,722 British adolescents aged 14–18 years, this study explored whether perceived father involvement can be associated with school attitudes even after controlling for perceived mother involvement. Multiple regression analysis showed that both father involvement and mother involvement contributed significantly and independently to positive school attitudes. Furthermore, the association between father involvement and school attitudes was the same for sons and daughters. We did not find evidence to support the notion that being in a non‐intact family weakens the association between perceived father involvement and school attitudes. Finally, there was no evidence suggesting that the impact of perceived father involvement on school attitudes depends on the level of perceived mother involvement. © 2002, Wiley Periodicals, Inc.
Exploring the re‐evaluated interpretation of hydrophobicity to explain rates of Diels–Alder reactions in aqueous salt solutions
Authors: Kumar Anil , Deshpande Suvarna S.
Published: October 2002

The recently proposed correlation between hydrophobicity and internal pressure offers quantitative support to our understanding on the rate enhancement of Diels–Alder reactions in water and its salt solutions. Copyright © 2002 John Wiley & Sons, Ltd.
Substituent effects in solvolysis of 1,1‐diphenylethyl p‐nitrobenzoates. Symmetrically disubstituted and monosubstituted systems
Authors: Fujio Mizue , Uddin Md. Khabir , Kim Hyun‐Joong , Tsuno Yuho
Published: October 2002

The rates of solvolysis of 1,1‐diarylethyl p‐nitrobenzoates and chlorides were determined conductimetrically at 25 °C in 80% (v/v) aqueous acetone. Applying the Yukawa–Tsuno (Y–T) equation, the symmetrical (X = Y) subseries gave a precise additivity relationship for the whole substituent range with a ρsym value of −3.78 and an rsym value of 0.77. While any Y subsets gave statistically less reliable Y–T correlations, the apparent ρ value changed significantly depending on the fixed Y substituents; the ρ value decreases with the more electron‐donating fixed substituents Y, which is compatible with the Hammond shift of the transition state coordinate. Nevertheless, the concave correlations of the More O'Ferrall non‐linearity relationship for any Y subsets are not in line with what is expected from the reactivity–selectivity relationship suggesting an anti‐Hammond shift of transition state. However, we found a precise extended Brønsted relationship between the pK values of 1,1‐diarylethylenes and solvolysis rate process with a constant slope of α = 1.03 ± 0.03. This is direct evidence indicating that there is no significant shift of the transition‐state coordinate over the whole range of substituent change. Copyright © 2002 John Wiley & Sons, Ltd.
Solvolysis of chiral cyclohexylidenemethyl triflate. Evidence against a primary vinyl cation intermediate
Authors: Fujita Morifumi , Yamamoto Akiyo , Sugimura Takashi , Okuyama Tadashi
Published: October 2002

Solvolysis of (R)‐4‐methylcyclohexylidenemethyl triflate (6) was examined at 140 °C in various aqueous methanol and some other alcoholic solvents. The main product was (R)‐4‐methylcycloheptanone that maintains the stereochemical purity of 6, with accompanying 4‐methylcyclohexanecarbaldehyde. In the presence of bromide ion, the bromide substitution product was also obtained, mostly with inversion of configuration. It is concluded that the solvolysis does not involve the formation of the primary vinyl cation but proceeds via σ‐bond participation to form the rearranged cycloheptenyl cation as an intermediate. Copyright © 2002 John Wiley & Sons, Ltd.
Photochromism of dihydroindolizines. Part II—Synthesis and photophysical properties of new photochromic IR‐sensitive photoswitchable substituted fluorene‐9′‐styrylquinolinedihydroindolizines
Authors: Ahmed Saleh Abdel‐Mgeed
Published: October 2002

Twenty‐nine new photochromic 2,4,7‐substituted fluorene‐9′‐styrylquinolinedihydroindolizines (DHIs) 4a–χ were prepared in 45–75% yield via nucleophilic addition of 4‐styrylquinolines 2a–k to substituted spirocyclopropenes 1a–c. The absorption maxima (λmax) of the colored betaines 3a–χ were detected by flash photolysis measurements. All betaines 3a–χ showed two absorption maxima, one in the visible region (450–525 nm) and another in the IR region (825–950 nm). Absorption spectra of betaines 3a–χ were also recorded at low temperature (77 K) by FT‐UV–Vis–near‐IR spectroscopy. The kinetics of the fast cyclizing process of betaines 3a–χ to DHIs 4a–χ were studied by millisecond flash photolysis and were found to take place in the millisecond range (35–310 ms in dichloromethane solution and 50–425 ms in methanol solution). A transient lifetime (ca 1 ms), measured using laser flash photolysis, was attributed to the transformation of (Z) to (E)‐betaines 3. Large solvatochromic effects on the absorption maxima (λmax) and a substantial increase in the half‐lives (t1/2) with solvent polarity of betaines­3a–χ were also observed. Copyright © 2002 John Wiley & Sons, Ltd.
Solvent‐dependent fluorescence of donor‐substituted (E)‐1,2‐bis(stilbenyl‐1,3,4‐oxadiazolyl)ethenes
Authors: Detert Heiner , Sugiono Erli , Kruse Gabriele
Published: October 2002

The Huisgen reaction of aryltetrazoles and fumaryl chloride leads to symmetrically aryl‐substituted 1,2‐bis(1,3,4‐oxadiazolyl)ethenes. Molecules with extended conjugated systems are accessible using stilbenyltetrazoles or higher homologues. The substitution with solubility‐permitting alkoxy side‐chains results in molecules of C2h symmetry, consisting of a central electron‐accepting segment and two terminal electron density‐releasing units. The solvatochromism of the absorption spectra is negligible, while in the emission spectra a strong positive solvatochromism connected with a dramatic decrease of the quantum yield is observed, indicating intramolecular charge transfer. The influences of different alkoxy substitution patterns on the luminescence properties are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
β‐Butyrolactone polymerization initiated with tetrabutylammonium carboxylates: A novel approach to biomimetic polyester synthesis
Authors: Kurcok Piotr , Śmiga Monika , Jedliński Zbigniew
Published: October 2002

The anionic ring‐opening polymerizations of (R,S)‐β‐butyrolactone and (S)‐β‐butyrolactone initiated with tetrabutylammonium salts of carboxylic acids as initiators were investigated. Poly[(R,S)‐3‐hydroxybutyrate] and poly[(R)‐3‐hydroxybutyrate], with relatively high molecular weights (170,000 and 35,000, respectively) and low molecular weight distributions, were synthesized. Moreover, biomimetic poly(3‐hydroxybutyrate)s with well‐defined microstructures and predictable iso‐dyad contents were obtained. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2184–2189, 2002
Relation between the reactivities of vinyl monomers in ionic polymerizations and their 1H NMR spectra
Authors: Hatada Koichi , Kitayama Tatsuki , Nishiura Takafumi , Shibuya Wataru
Published: October 2002

1H NMR chemical shifts of the protons in the vinyl groups of monomers are correlated with their reactivities in anionic, coordinated anionic, and cationic polymerizations. The relative reactivities of styrenes in anionic addition reactions with living polystyrene increase linearly with the chemical shift of the proton trans to the substituent (δH1). Only the plot for 2,4,6‐trimethylstyrene deviates very much from the linear relation because of the large steric hindrance. The relative reactivities of methacrylates in anionic copolymerizations increase with increasing chemical shifts of protons attached to the β‐carbon of methacrylates. In cationic polymerizations of styrenes, the relative reactivities decrease with increasing δH1. The relative reactivities in coordinated anionic polymerizations with Ti‐containing Ziegler initiators show a typical feature of cationic polymerization, and those with V‐containing initiators show a typical feature of anionic polymerization, indicating the importance of the coordination process in the propagation reaction with Ti‐containing initiator systems. From the results, it can be concluded that the chemical shifts of the protons attached to the β‐carbon of vinyl monomers can be used as a practical measure of the reactivity of vinyl monomers in ionic polymerizations and also as a tool for understanding the mechanism of polymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2134–2147, 2002
Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. III. Methanolytic degradation
Authors: Kint Darwin P. R. , Martinez de Ilarduya Antxon , Bou Jordi J. , Muñoz‐Guerra Sebastián
Published: October 2002

The methanolytic degradation of poly(ethylene terephthalate) (PET) copolymers containing nitroterephthalic units was investigated. Random poly(ethylene terephthalate‐co‐nitroterephthalate) copolyesters (PETNT) containing 15 and 30 mol % nitrated units were prepared from ethylene glycol and a mixture of dimethyl terephthalate and dimethyl nitroterephthalate. A detailed study of the influence of the nitro group on the methanolytic degradation rate of the nitrated bis(2‐hydroxyethyl) nitroterephthalate (BHENT) model compound in comparison with the nonnitrated bis(2‐hydroxyethyl) terephthalate (BHET) model compound was carried out. The kinetics of the methanolysis of BHENT and BHET were evaluated with high‐performance liquid chromatography and 1H NMR spectroscopy. BHENT appeared to be much more reactive than BHET. The methanolytic degradation of PET and PETNT copolyesters at 80 °C was followed by changes in the weight and viscosity, gel permeation chromatography, differential scanning calorimetry, scanning electron microscopy, and 1H and 13C NMR spectroscopy. The copolyesters degraded faster than PET, and the degradation increased with the content of nitrated units and occurred preferentially by cleavage of the ester groups placed at the meta position of the nitro group in the nitrated units. For both PET and PETNT copolyesters, an increase in crystallinity accompanied methanolysis. A surface degradation mechanism entailing solubilization of the fragmented polymer and consequent loss of mass was found to operate in the methanolysis of the copolyesters. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2276–2285, 2002
Cure kinetics of the ring‐opening metathesis polymerization of dicyclopentadiene
Authors: Kessler M. R. , White S. R.
Published: October 2002

The 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

Novel 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

Neutral 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

A 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

To 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

Our 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

We 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

Pulmonary 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

BACKGROUND

Prostate 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.

METHODS

We 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.

RESULTS

The 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.

CONCLUSION

Our 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

The 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

A 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

An 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

An 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

Acidic 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

We 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

Plumieride 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

A 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

A 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.
Improved bounds for sampling contingency tables
Authors: Morris Ben J.
Published: October 2002

We study the problem of sampling contingency tables (nonnegative integer matrices with specified row and column sums) uniformly at random. We give an algorithm which runs in polynomial time provided that the row sums ri and the column sums cj satisfy ri = Ω(n3/2m log m), and cj = Ω(m3/2n log n). This algorithm is based on a reduction to continuous sampling from a convex set. The same approach was taken by Dyer, Kannan, and Mount in previous work. However, the algorithm we present is simpler and has weaker requirements on the row and column sums. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 135–146, 2002
Use of differential charging to analyse microscopic specimens of Azolla leaves by XPS
Authors: Genet Michel J. , Jacques Christine , Mozes Nava , Hove Charles Van , Lejeune André , Rouxhet Paul G.
Published: October 2002

Cavity cuticles that surround the bacterial symbionts residing in the leaf cavities of the aquatic fern Azolla and Azolla leaf cuticle on the epidermis outside the cavity (outer cuticle) were submitted to XPS analysis. Differential charging enabled the signals of the microscopic sample and the support signals to be differentiated. The cavity cuticle has a composition similar to cutin. In comparison with the outer cuticle, it is characterized by a lower concentration of aliphatic chains and a higher concentration of oxygen‐containing functions. This has implications in term of solute transport between the leaf and the bacteria. Copyright © 2002 John Wiley & Sons, Ltd.
Sample size and power determination for clustered repeated measurements
Authors: Liu Aiyi , Shih W. J. , Gehan E.
Published: October 2002

It is common in epidemiological and clinical studies that each subject has repeated measurements on a single common variable, while the subjects are also ‘clustered’. To compute sample size or power of a test, we have to consider two types of correlation: correlation among repeated measurements within the same subject, and correlation among subjects in the same cluster. We develop, based on generalized estimating equations, procedures for computing sample size and power with clustered repeated measurements. Explicit formulae are derived for comparing two means, two slopes and two proportions, under several simple correlation structures. Copyright © 2002 John Wiley & Sons, Ltd. abstract