bluuebunny/crossref_metadata_2025_split huggingface dataset:
In utero therapy for lower urinary tract obstruction
Authors: Agarwal Sanjiv K. , Fisk Nicholas M. 
Published: August 2002

AbstractLower urinary tract obstruction has a significant impact on neonatal and child health. Pulmonary hyperplasia and renal impairment could be direct or indirect consequences of this condition leading to significant morbidity and mortality. Evaluation of fetuses with suspected lower urinary tract obstruction is performed not only to confirm the diagnosis but also to assess renal prognosis. Ultrasound examination and urinary analysis aid in the evaluation of these fetuses. The decision to perform fetal intervention in these cases is a difficult one. Vesico‒amniotic fetal shunting, open fetal surgery and more recently endoscopic fetal surgery for this condition are available as possible modalities of fetal intervention. Case selection for fetal intervention is extremely important in order to both avoid unnecessary intervention in those unlikely to survive, and also to avoid procedure related complications in fetuses likely to do well without intervention.Vesico‒amniotic shunting has the advantage of bypassing the obstruction, however it is often associated with complications. Open fetal surgery is not usually recommended because of the complications and high fetal loss rate. Endoscopic surgery to visualise and treat the cause of lower urinary tract obstruction has been tried. Fetal endoscopic surgery is in its infancy and endoscopic procedures are limited to a few groups.This current review addresses evaluation, case selection and therapeutic options for lower urinary tract obstruction in utero. It also discusses the limited data against which the efficacy of the various options can be assessed. The current state of fetal intervention is detailed in the present review. Copyright © 2001 John Wiley & Sons, Ltd.
Maternal serum leptin concentration during the second trimester of pregnancy: association with fetal chromosomal abnormalities
Authors: Rizos Demetrios , Hassiakos Demetrios , Grigori‐Kostaraki Panagiota , Sarandakou Angeliki , Botsis Demetrios , Salamalekis Emmanuel 
Published: August 2002

AbstractRecent studies suggest that leptin, the product of the obese gene, is produced by the placenta during pregnancy. The present study addressed the question whether second trimester maternal serum leptin could be altered by fetal Down syndrome or Edwards syndrome. Maternal serum leptin concentrations were measured in 18 pregnancies complicated with Down syndrome, six pregnancies complicated with Edwards syndrome and 183 uncomplicated pregnancies during the second trimester of pregnancy. The present results demonstrate that leptin concentrations in uncomplicated pregnancies slightly decrease from the 16th week of pregnancy, reaching a minimum of 18.8 ng/ml around the 20th week, and then rapidly increase to 28.2 ng/ml by the 24th week. Leptin correlation with maternal body weight decreases from r=0.695 at 16–17 week of gestation to r=0.544 at >22 weeks of gestation. There was no significant difference between the mean MoMs of Down syndrome‐ (0.926) or Edwards syndrome‐ (0.960) affected pregnancies and normal pregnancies (1.002). A weak correlation (r=0.18, p<0.02) was observed between corrected leptin MoMs and human chorionic gonadotrophin (hCG) MoMs in normal pregnancies. It is assumed that around the 20th week of pregnancy placental leptin production is activated or at least is accelerated and it is added to the amount of leptin produced by maternal adipose tissue. Fetal Down syndrome or Edwards syndrome does not seem to alter maternal leptin concentration and therefore leptin cannot be used as a marker for these chromosomal abnormalities in the early second trimester of pregnancy. Copyright © 2002 John Wiley & Sons, Ltd.
Associations between a hydrophobically modified, degradable, poly(malic acid) and a β‐cyclodextrin polymer in solution
Authors: Moine Laurence , Amiel Catherine , Brown Wyn , Guerin Philippe 
Published: August 2002

AbstractA new associating system has been elaborated from mixing a degradable polymer, poly(β‐malic acid‐co‐β‐ethyladamantyl malate), and a β‐cyclodextrin polymer in aqueous solution. Viscosity and dynamic light scattering measurements have been made on solutions of the single copolyester and of mixtures of both polymers. Studies on copolyesters with different percentages of hydrophobic groups (0–7.5%) show that a small proportion of the chains (less than 5% in weight) are aggregated in large structures (100 nm) which dominate the scattering intensity. The mixtures exhibit slow diffusive relaxation modes which correlate with a large viscosity enhancement at low concentration. These effects, which depend sensitively on pH, are attributed to the presence of polydisperse complexes of copolyester and β‐cyclodextrin polymer. The influence of pH, ionic strength, medium composition, and concentration were examined on the mixture of copolymers. It was found that the association properties are controlled by the net charge on the amphiphilic copolyester.© 2001 Society of Chemical Industry
Oxidative copolymerization of indene with p‐tert‐butylstyrene: Synthesis, characterization, thermal analysis, and reactivity ratios
Authors: De Priyadarsi , Sathyanarayana D. N. 
Published: August 2002

AbstractCopolyperoxides of indene and p‐tert‐butylstyrene of different compositions were synthesized by free‐radical‐initiated oxidative copolymerization. The compositions of the copolyperoxides, obtained from 1H and 13C NMR spectra, were used to calculate the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of indene units in random placement in the copolyperoxides. Thermal‐degradation studies by differential scanning calorimetry and electron‐impact mass spectrometry supported alternating peroxide units in the copolymer backbone. The activation energy for thermal degradation suggested that the degradation was dependent on the dissociation of the peroxide (OO) bonds in the backbone of the copolyperoxide chain. The flexibility of the copolyperoxides was examined in terms of the glass‐transition temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 9–18, 2002
Reactivity ratios for the terpolymerization of methyl methacrylate, vinyl acetate, and molecular oxygen
Authors: De Priyadarsi , Sathyanarayana D. N. 
Published: August 2002

AbstractThe copolymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) under high oxygen pressure was investigated. Copolyperoxides of various compositions were synthesized by the free‐radical‐initiated oxidative copolymerization of MMA and VAc monomers. The copolyperoxide compositions obtained from 1H and 13C NMR spectra were used for determining the reactivity ratios of the monomers. The reactivity ratios indicated a larger proportion of MMA units statistically placed in the copolyperoxides. A theoretical analysis based on semiempirical AM1 calculations was performed to support the reactivity ratios. NMR studies showed irregularities in the copolyperoxide chain due to the cleavage reactions of the propagating peroxide radical. Thermal analyses of the copolyperoxides by differential scanning calorimetry gave evidence for the presence of alternating peroxide units in the copolyperoxide chain. The activation energies of thermal degradation suggested that degradation was controlled by the dissociation of the peroxide (OO) bond in the backbone of the copolyperoxide chain. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 564–572, 2002; DOI 10.1002/pola.10115
Reactive blending of functional polysiloxanes with poly(butylene terephthalate): Clarification of reaction mechanisms and kinetics from a model compound study
Authors: Fustin C. A. , Sclavons M. , Verhelst V. , Vermylen V. , Bebelman S. , Merlin P. , Bailly C. 
Published: August 2002

AbstractWe clarify the reaction mechanisms and kinetics in melt‐reacted blends consisting of functional polysiloxanes and poly(butylene terephthalate) (PBT) with a model compound study. As models for polysiloxanes, we have selected two monodisperse ω‐functionalized siloxane oligomers with SiH and Sivinyl moieties. To mimic PBT, we have chosen low molecular weight compounds representative for in‐chain and end‐functional groups of the polymer; ester, carboxylic acid, alcohol, and vinyl. Uncatalyzed and platinum‐catalyzed reactions have been performed in sealed vials. Reaction products have been characterized by gradient polymer elution chromatography, Fourier transform infrared spectroscopy, and size exclusion chromatography. PBT functional groups reactive toward functional siloxane oligomers at high temperatures in the presence and absence of a catalyst have been identified, and an estimate of relative reaction kinetics has been provided. We suggest reaction mechanisms compatible with our results and with literature data. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1952–1961, 2002
Absolute absorption measurements of polymer films for optical waveguide applications by photothermal deflection spectroscopy
Authors: Wu Liu‐Ming , Knoesen André 
Published: August 2002

AbstractA self‐contained experimental technique is proposed for measuring the absolute optical absorption spectra, thermal diffusivity, and thermal conductivity of polymer thin films. The technique is based on photothermal deflection spectroscopy and provides sensitivity that is high enough to quantify the very small optical absorption losses in polymer films used for optical waveguide applications. The capabilities of the technique are demonstrated with measurements performed on thin films of poly(methyl methacrylate) and a fluorinated polymer (CYTOP). An error analysis is presented, and the factors are discussed that influence the accuracy of the technique. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2717–2726, 2001
Indentation of poly(methyl methacrylate) under high‐pressure gases
Authors: Flichy N. M. B. , Kazarian S. G. , Lawrence C. J. , Briscoe B. J. 
Published: August 2002

AbstractThe variation of the indentation hardness of a high molecular weight poly(methyl methacrylate) (PMMA) subjected to CO2 and Ar at high pressure was measured in situ. The samples were subjected to gas exposure for 3 h at 40 °C before a conical indenter of an included angle at 105 °, with a fixed load of 0.237 kg, was applied for a loading time of 60 s. The data show that both CO2 and Ar reduce the hardness of PMMA to a comparable extent at low pressures. The hardness of PMMA subjected to Ar indicates a minimum at about 4 MPa and then increases. CO2 produced a monotone decreasing trend in hardness in the pressure range studied, and the glass‐transition temperature (Tg) was achieved at about 6.0 MPa. The change in hardness is attributed to plasticization of the polymer matrix that is more extensive for CO2. The relationship between the change in hardness for this PMMA subjected to high‐pressure CO2, the corresponding change in the Tg, and the associated swelling of the polymer is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3020–3028, 2001
Influence of the β‐crystalline phase on the mechanical properties of unfilled and calcium carbonate‐filled polypropylene: Ductile cracking and impact behavior
Authors: Labour T. , Vigier G. , Séguéla R. , Gauthier C. , Orange G. , Bomal Y. 
Published: August 2002

AbstractThe β‐crystalline form of isotactic poly(propylene) (PP) has been long recognized to have a greater mechanical absorption capacity than the α‐crystalline form. This is of major importance for improving impact properties and crack resistance of injection‐molding parts. Unfilled PP samples together with calcium carbonate‐filled PP samples having various β/α‐phase ratios, with nearly constant morphological parameters, have been investigated from the standpoint of ductile crack propagation and impact behavior. The presence of the β‐crystalline phase turned out to improve both properties. The β spherulites are notably more prone to craze initiation than α spherulites that display a propensity for cracking. Subsequent crack propagation appears to be faster in the latter ones. The plastic zone ahead from the crack tip broadens, and the specific plastic energy increases with increasing β‐phase content. The lower elastic limit of the β phase is likely to promote the early crazing. However, the suspected higher density of tie molecules in β spherulites provides more numerous and stiffer microfibrils. The impact strength of PP is also improved by the presence of β crystals as a result of greater energy‐absorption capabilities. However, filled samples turned out insensitive to the β phase. A discussion is made about the origins of the β‐phase‐induced improvement of the mechanical properties. The possible role of the β → α transition is also explained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 31–42, 2002
Mesoscopic modeling of the polymerization, morphology, and crystallization of stereoblock and stereoregular polypropylenes
Authors: Madkour Tarek M. , Mark James E. 
Published: August 2002

AbstractThermoplastic elastomers require domains that act as physical crosslinks, and these can be either glassy regions or crystallites. For crystallites in a polymer such as polypropylene (PP), the challenge is to develop polymerizations that form the long stereoregular chain sequences required to produce crystallites large enough to act as stable temporary crosslinks but not so many of them that the material becomes a significantly crystalline thermoplastic rather than an elastomer. For PP, the requirement is for long isotactic sequences within predominantly elastomeric atactic chains, and catalysts required to achieve such an unusual stereoblock structure are now available. This provided encouragement for the simulations described herein that illustrate some relationships between polymerization mechanisms and distributions of isotactic sequences (particularly those long enough to crystallize). A Windle‐type Monte Carlo algorithm was then applied to arrays of the representative PP chains in searches for matches of crystallizable sequences. This approach provided estimates of degrees of crystallinity, melting points, interfacial free energies, standard free energies of fusion, and Young's moduli at small extensions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 840–853, 2002
Diffusion of oxygen and carbon dioxide in thermally crystallized syndiotactic polystyrene
Authors: Hodge K. , Prodpran T. , Shenogina N. B. , Nazarenko S. 
Published: August 2002

AbstractThe diffusion, solubility, and permeability behavior of oxygen and carbon dioxide were studied in amorphous and semicrystalline syndiotactic polystyrene (s‐PS). The crystallinity was induced in s‐PS by crystallization from the melt and cold crystallization. Crystalline s‐PS exhibited very different gas permeation behavior depending on the crystallization conditions. The behavior was attributed to the formation of different isomorphic crystalline forms in the solid‐state structure of this polymer. The β crystalline form was virtually impermeable for the transport of oxygen and carbon dioxide. In contrast, the α crystalline form was highly permeable for the transport of oxygen and carbon dioxide. High gas permeability of the α crystals was attributed to the loose crystalline structure of this crystalline form containing nanochannels oriented parallel to the polymer chain direction. A model describing the diffusion and permeability of gas molecules in the composite permeation medium, consisting of the amorphous matrix and the dispersed crystalline phase with nanochannels, was proposed. Cold crystallization of s‐PS led to the formation of a complex ordered phase and resulted in complex permeation behavior. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2519–2538, 2001
Bronchiolitis obliterans organizing pneumonia (BOOP) in a child with mild‐to‐moderate asthma: Evidence of mast cell and eosinophil recruitment in lung specimens
Authors: Barbato Angelo , Panizzolo Cristina , D'Amore Emanuele S.G. , La Rosa Mario , Saetta Marina 
Published: August 2002

AbstractBronchiolitis obliterans with organizing pneumonia (BOOP) is rarely described in children and little is known about its pathogenesis. This paper reports on an 11‐year‐old patient suffering from mild‐to‐moderate asthma. He presented with a retrocardiac density at chest computed tomography scan that was slow to resolve and failed to respond to antibiotic therapy. Open lung biopsy revealed a histological picture with buds of granulation tissue in respiratory bronchioles and alveolar ducts, with organized extensions into the alveoli. The use of monoclonal antibodies on biopsy specimens demonstrated the presence of an inflammatory process affecting not only the thickened alveolar walls, but also the remaining lung parenchyma, the pulmonary arteries, and the bronchioles. The inflammatory infiltrate consisted mainly of mast cells and eosinophils. The clinical condition improved with steroid therapy. To the best of the authors' knowledge, this is the first report of BOOP in an asthmatic child with recruitment of mast cells and eosinophils documented by using monoclonal antibodies. Pediatr Pulmonol. 2001; 31:394–397. © 2001 Wiley‐Liss, Inc.
Polymorphic repeats in the androgen receptor gene in high‐risk sibships
Authors: Miller Elizabeth A. , Stanford Janet L. , Hsu Li , Noonan Elizabeth , Ostrander Elaine A. 
Published: August 2002

AbstractBackgroundGenetic susceptibility may explain some familial clusters of prostate cancer. The polymorphic androgen receptor (AR) gene, which mediates androgen activity in the prostate, is a candidate gene that may influence predisposition to the disease.MethodsWe analyzed the polymorphic (CAG)n and (GGN)n repeats within the AR gene in men from 51 high‐risk prostate cancer sibships, which included at least one affected and one unaffected man (n = 210). We compared repeat lengths of men with prostate cancer (n = 140) to their brothers (n = 70) without disease, stratified by median age at diagnosis of affected men within each sibship. Conditional logistic regression was used to compute odds ratios (OR) and 95% confidence intervals to evaluate associations between prostate cancer and repeat length.ResultsThe OR for prostate cancer associated with short (CAG)n repeats (<22) compared to longer repeats (≥22) was 1.13 (95% CI 0.5–2.4) overall, but was higher in sibships with a median age of <66 years at diagnosis (OR = 1.72, 95% CI 0.5–6.0). The (GGN)n array also was not associated with prostate cancer in general. However, in older men (≥66 years), there was a modest elevation in risk (OR = 1.56, 95% CI 0.6–4.1) among those with short repeats (GGN of ≤16). Men with both a short (CAG)n (<22) and a short (GGN)n (≤16) array were not at higher risk (OR = 1.06) compared to men with two long repeats [(CAG)n ≥22 and (GGN)n >16)].ConclusionsThese results suggest that the (CAG)n and (GGN)n repeats in the AR gene do not play a major role in familial prostate cancer. Prostate 48:200–205, 2001. © 2001 Wiley‐Liss, Inc.
Coupling of ligand binding and dimerization of helix‐loop‐helix peptides: Spectroscopic and sedimentation analyses of calbindin D9k EF‐hands
Authors: Julenius Karin , Robblee James , Thulin Eva , Finn Bryan E. , Fairman Robert , Linse Sara 
Published: August 2002

AbstractIsolated Ca2+‐binding EF‐hand peptides have a tendency to dimerize. This study is an attempt to account for the coupled equilibria of Ca2+‐binding and peptide association for two EF‐hands with strikingly different loop sequence and net charge. We have studied each of the two separate EF‐hand fragments from calbindin D9k. A series of Ca2+‐titrations at different peptide concentrations were monitored by CD and fluorescence spectroscopy. All data were fitted simultaneously to both a complete model of all possible equilibrium intermediates and a reduced model not including dimerization in the absence of Ca2+. Analytical ultracentrifugation shows that the peptides may occur as monomers or dimers depending on the solution conditions. Our results show strikingly different behavior for the two EF‐hands. The fragment containing the N‐terminal EF‐hand shows a strong tendency to dimerize in the Ca2+‐bound state. The average Ca2+‐affinity is 3.5 orders of magnitude lower than for the intact protein. We observe a large apparent cooperativity of Ca2+ binding for the overall process from Ca2+‐free monomer to fully loaded dimer, showing that a Ca2+‐free EF‐hand folds upon dimerization to a Ca2+‐bound EF‐hand, thereby presenting a preformed binding site to the second Ca2+‐ion. The C‐terminal EF‐hand shows a much smaller tendency to dimerize, which may be related to its larger net negative charge. In spite of the differences in dimerization behavior, the Ca2+ affinities of both EF‐hand fragments are similar and in the range lgK = 4.6–5.3. Proteins 2002;47:323–333. © 2002 Wiley‐Liss, Inc.
Application of coupled liquid chromatography–mass spectrometry in photolysis studies of the herbicide triflusulfuron‐methyl
Authors: Chafik Nourrddine , Mansour Mohammed , Elamrani Btissam , Schramm Karl‐Werner , Kettrup Antonius , Elamrani M Khalid 
Published: August 2002

AbstractThe photochemical fate of the herbicide triflusulfuron‐methyl in aqueous solution under UV light (λ > 290 nm) was investigated. Nine photoproducts were detected and tentatively identified by LC/MS and LC/MS/MS analysis. The main routes of degradation involve the cleavage and/or contraction of the sulfonylurea bridge with the elimination of sulfur dioxide, which increases the acidity of the reaction medium. On the basis of the results obtained a photodegradation pathway is proposed.© 2001 Society of Chemical Industry
Laboratory studies to assess the risk of development of resistance to zoxamide
Authors: Young David H , Spiewak Sandra L , Slawecki Richard A 
Published: August 2002

AbstractLaboratory studies were conducted to evaluate the risk of developing field resistance to zoxamide, a new Oomycete fungicide which acts on microtubules. Zoxamide, metalaxyl and dimethomorph were compared with respect to the ease with which fungicide‐resistant mutants could be isolated and their level of resistance. Attempts to generate mutants of Phytophthora capsici and P infestans with resistance to zoxamide by mycelial adaptation on fungicide‐amended medium were unsuccessful. Similarly, changes in sensitivity to zoxamide were small (resistance factors ≤2.2) in mutants of P capsici isolated by chemical mutagenesis of zoospore cysts. In parallel experiments with metalaxyl, highly resistant mutants were obtained using both adaptation (P capsici or P infestans) and chemical mutagenesis (P capsici). For dimethomorph, chemical mutagenesis (P capsici) yielded moderately resistant mutants (maximum resistance factor = 20.9), and adaptation (P capsici or P infestans) did not induce resistance. It is proposed that failure to isolate mutants resistant to zoxamide results from the diploid nature of Oomycete fungi and the likelihood that target‐site mutations would produce a recessive phenotype. Our studies suggest that the risk of a highly resistant pathogen population developing rapidly in the field is much lower for zoxamide than for metalaxyl. However, as with any site‐specific fungicide, appropriate precautions against resistance development should be taken.© 2001 Society of Chemical Industry