bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular cytogenetic differences between histological subtypes of malignant mesotheliomas: DNA cytometry and comparative genomic hybridization of 90 cases
Authors: Krismann Michael , Müller Klaus‐Michael , Jaworska Malgorzata , Johnen Georg 
Published: October 2002

AbstractIt is established that subtypes of human malignant mesotheliomas (MM) are associated with different survival times. Ninety cases of MM were examined using DNA cytometry and comparative genomic hybridization (CGH), with emphasis on the main histological subtypes; epithelioid, sarcomatoid and biphasic. A comparison by DNA cytometry revealed moderate differences, with the rare subgroup of mesodermomas having the highest and the sarcomatoid group the lowest rate of aneuploidy. Using CGH, 6.2 chromosomal imbalances per case on average could be detected. Losses (4.1/case) were more common than gains of chromosomal material (2.1/case). MM show no single, specific defect, but a typical pattern of genomic defects can be attributed to this tumour entity. Common losses are clustered at the chromosomal regions 9p21 (34%), 22q (32%), 4q31–32 (29%), 4p12–13 (25%), 14q12–24 (23%), 1p21 (21%), 13q13–14 (19%), 3p21, 6q22, 10p13–pter and 17p12–pter (16% each). Common gains are located on 8q22–23 (18%), 1q23/1q32 (16%), 7p14–15 and 15q22–25 (14% each). While differences in the frequencies of the defects between epithelioid and sarcomatoid MM are not as pronounced as are seen with the pleomorphic mesodermomas, several chromosomal locations (3p, 7q, 15q, 17p) show significant variations. The most pronounced distinguishing feature of sarcomatoid MM is a more than fourfold higher number of amplicons. These data indicate that MM has a distinctive tumour biology with a broad spectrum of heterogeneity, as reflected in morphology and also, more subtly, in the patterns of chromosomal imbalances of the subtypes. Copyright © 2002 John Wiley & Sons, Ltd.
The expression of E‐cadherin and catenins in colorectal tumours from familial adenomatous polyposis patients
Authors: El‐Bahrawy Mona A. , Talbot Ian C. , Poulsom Richard , Jeffery Rosemary , Alison Malcolm R. 
Published: October 2002

AbstractFamilial adenomatous polyposis patients (FAP) harbour a germline mutation of the adenomatous polyposis coli gene (APC), and APC mutations are early events in the development of sporadic colorectal neoplasms. The APC protein interacts with β‐catenin and γ‐catenin and APC mutations are believed to play a role in the altered levels of β‐catenin in colorectal tumours. Immunohistochemical studies have shown changes in the expression and distribution of E‐cadherin and catenins in sporadic colorectal neoplasms. This study assessed the expression and distribution of E‐cadherin and catenins in colorectal neoplasms and non‐neoplastic mucosa from FAP patients. The expression and cellular distribution of E‐cadherin and catenins were studied by immunohistochemistry in 61 adenomas, five carcinomas, and non‐neoplastic mucosa from 18 FAP patients. mRNA levels in the carcinomas were studied by in situ hybridization. The expression of E‐cadherin and catenins was increased in over 80% of the adenomas, with evident cytoplasmic immunoreactivity. There was increased expression of E‐cadherin and catenin in the carcinomas, with a notable increase in the levels of mRNA, in comparison with the non‐neoplastic mucosa. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal identification of esophageal atresia: the role of ultrasonography for evaluation of functional anatomy
Authors: Shulman Adrian , Mazkereth Rami , Zalel Yaron , Kuint Jacob , Lipitz Shlomo , Avigad Itamar , Achiron Reuwen 
Published: October 2002

AbstractObjectiveTo suggest a new ultrasonographic approach for prenatal diagnosis of esophageal atresia (EA).MethodsSince 1995, whenever EA is suspected, we perform a systematic multiplanar ultrasonographic scanning of the fetal upper body in order to demonstrate an esophageal pouch. This includes three image plans of the neck and upper chest: coronal, sagittal and axial views in the cephalic direction. The scan time is 20–30 min.ResultsTwenty‐five pregnant patients were referred during the period under study for prenatal examinations due to polyhydramnios and/or absent or small stomach. In six fetuses an esophageal pouch was demonstrated at ultrasonography in utero, thus a definitive diagnosis of EA was obtained. All six were confirmed with EA postpartum. In 19 fetuses an esophageal pouch was not demonstrated and all delivered normal neonates. During the same period two additional newborns, who were not included in the referred patients because amniotic fluid volume and stomach size were normal, were diagnosed postpartum with EA. The earliest gestational age of pouch visualization was at 23 weeks. The sagittal view was the best for visualizing a low‐level pouch, and the coronal view was optimal for revealing a high pouch.ConclusionsOur three‐sectional view of the neck and upper chest is useful for in utero detection of esophageal pouch that may enhance the prenatal diagnosis of EA. The positive predictive value for prenatal ultrasound for detecting EA is 100% with a sensitivity of 80%. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal diagnosis and intrafamilial clinical heterogeneity of Fraser syndrome
Authors: Rousseau Thierry , Laurent Nicole , Thauvin‐Robinet Christel , Lionnais Stéphanie , Durand Christine , Faivre Laurence , Sagot Paul 
Published: October 2002

AbstractFraser syndrome (MIM 219000) is a rare disorder of autosomal recessive inheritance, characterized by the association of cryptophthalmos, syndactyly and genital abnormalities. Here we report on two cases of Fraser syndrome (cryptophthalmos syndrome) in a non‐consanguineous couple, with variable expression in echographic, clinical and autopsy findings. Furthermore, we highlight the difficulties in prenatal diagnosis of Fraser syndrome. Copyright © 2002 John Wiley & Sons, Ltd.
Outcome of prenatally diagnosed trisomy 6 mosaicism
Authors: Wallerstein Robert , Oh Tracey , Durcan Judy , Abdelhak Yaakov , Clachko Mark , Aviv Hana 
Published: October 2002

AbstractWe report the prenatal diagnosis of trisomy 6 mosaicism via amniocentesis, in which trisomy 6 cells were identified in three of five culture vessels with 33% (5/15) of colonies showing trisomic cells. The pregnancy was electively terminated and examination revealed minor abnormalities (shortening of the femurs, micrognathia, posterior malrotation of the ears, and bilateral camptomelia of the second digit of the hands and fifth digits of the feet). Cytogenetic analysis of the placenta showed trisomy 6 in 100% of 20 cells studied. Karyotype was 46,XX in 100 cells examined from fetal skin. There are relatively few prenatally diagnosed cases of mosaic trisomy 6 at amniocentesis. Confined placental mosaicism (CPM) has been postulated in other cases where follow‐up cytogenetic studies were not available. The present case differs from those previously reported, as it appears to represent CPM of chromosome 6 with phenotypic effects to the fetus. Copyright © 2002 John Wiley & Sons, Ltd.
What should we do about the obesity epidemic?
Authors: Barth Julian H. 
Published: October 2002

Abstractmagnified image
The current increase in obesity is occurring despite increasing awareness by the population at large of the benefits of healthy eating and exercise. Although weight gain is the direct result of a mismatch in energy balance, it is important to realise that there is a complex interplay between the environment and individual biology and behaviour. Management of obesity whether in a primary or secondary care setting requires a multi‐disciplinary team to produce an individualised approach to embrace food, exercise and behavioural change. The prevention of obesity requires a three‐level approach. First, there needs to be a co‐ordinated public health policy at national level to create an environment where it is easy to make healthy choices for physical activity and food. Second, there needs to be a policy that targets those individuals who are at risk of becoming obese and those who have lost weight to help prevent weight regain. Finally, there needs to be a systematic uptake of the established protocols for the management of individuals with obesity and its co‐morbidities. The challenge in the UK is to build imaginative networks that integrate all available resources both within the NHS and without, such as sports centres, fitness clubs and slimming clubs. Copyright © 2002 John Wiley & Sons, Ltd.
Thermoreversible gelation of a polystyrene–poly(ethylene/butylene)–polystyrene triblock copolymer in n‐octane/4‐methyl‐2‐pentanone solutions
Authors: Quintana Jose R , Hernáez Estíbaliz , Katime Issa 
Published: October 2002

AbstractThe thermoreversible gelation of a triblock copolymer polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene in n‐octane and two solvent mixtures of n‐octane and 4‐methyl‐2‐pentanone with a high n‐octane content has been studied. n‐Octane and 4‐methyl‐2‐pentanone are selective solvents for the middle poly(ethylene/butylene) block and the end polystyrene blocks, respectively. The influence of the solvent composition on the sol–gel transition and the mechanical properties of the gels was studied. The gel formation temperature increased with the copolymer concentration and the n‐octane content in the solvent system. The mechanical properties of the different gels were studied through oscillatory shear measurements. The concentration dependence of the elastic storage modulus showed an exponent close to that expected for gels in good solvents (2.25) that possess a structure similar to those of chemical networks.© 2002 Society of Chemical Industry
On the ‘curiosity’ of electrical self‐heating, static charge and electromagnetic shielding effectiveness from carbon black/aluminium flakes reinforced epoxy‐resin composites
Authors: El‐Tantawy Farid , Kamada K , Ohnabe H 
Published: October 2002

AbstractThis paper shows the wide application range (such as electrical self‐heating and electromagnetic shielding effectiveness) of composites consisting of conductive carbon black/aluminum flakes (CBA) filler and epoxy insulative matrix. The effect of CBA content on the network structure of epoxy matrix was investigated in detail. Static electrical conductivity increases linearly with the increase of filler concentration at the interface in epoxy composites. The large decrease of the conductivity as a function of the temperature is analyzed in terms of the negative temperature coefficient of conductivity (NTCC) effect. The influence of viscosity, surface energy and barrier highest energy on the NTCC behaviour in the composite is also considered. Based on these results, a new interpretation is proposed to explain the NTCC phenomena by computing the swelling force among conductive phases. The correlations of conductivity during the temperature cycling and activation energy were analyzed. The effects of dynamic ageing at various temperatures on the resistivity are reported. Current–voltage–temperature characteristics for epoxy with different contents of CBA were examined in detail. A model based on the law of energy conservation is proposed to calculate the specific heat and amount of heat dissipation. The static charge of the epoxy–CBA composites was estimated. The correlation between electromagnetic wave‐shielding effectiveness (EMS), conductivity and frequency of epoxy composites with different filler contents is also discussed. Furthermore, the effect of annealing on EMS of epoxy composites was examined.© 2002 Society of Chemical Industry
Direct observation of the fringed micelles structure of cellulose molecules solvated in dimethylacetamide/LiCl system
Authors: Yan Lifeng , Zhu Qingshi 
Published: October 2002

AbstractA dilute solution of cellulose in dimethylacetamide/LiCl was deposited on the surface of freshly cleaved mica, and the resulting morphologies of cellulose aggregates were observed by atomic force microscopy. It was found that cellulose molecules aggregated together following the fringed micelles model, and that the fringed micelles aggregated together to form larger fractal structures.© 2002 Society of Chemical Industry
Teacher and child variables as predictors of academic engagement among low‐income African American children
Authors: Tucker Carolyn M. , Zayco Rose A. , Herman Keith C. , Reinke Wendy M. , Trujillo Mark , Carraway Kirsten , Wallack Cory , Ivery Phyllis D. 
Published: October 2002

AbstractA causal model for understanding the complex interplay between student‐reported teacher behaviors, student self‐systems, and student engagement was tested. One hundred seventeen African American students in grades 1 through 12 completed a comprehensive questionnaire regarding teacher context, self, and engagement variables. A series of hierarchical regression analyses were conducted to test the hypothesized mediation models and to construct a path model. Most hypotheses were supported. Student self‐system variables (perceived competency and autonomy) mediated relations between teacher context (structure and autonomy support), and engagement. Contrary to predictions, however, teacher involvement exerted a strong and direct effect on student engagement even when controlling for grade level and self‐system variables. Given existing research showing that African American students are at risk for low teacher involvement and that engagement is critical for academic success, research and intervention strategies are urgently needed to promote teacher involvement with these students. © 2002 Wiley Periodicals, Inc.
Adolescent suicide: An ecological approach
Authors: Ayyash‐Abdo Huda 
Published: October 2002

AbstractAdolescent suicide, which has been ranked among the top 10 causes of death in the world, is an issue of increasing concern to school psychologists, educators, and parents. Here an ecological approach is proposed to enhance our understanding of how personal, interpersonal, and sociocultural factors contribute to the increased risk for suicide among adolescents. The ecological approach allows exploration of how adolescent suicide is determined by multiple factors related to the adolescent's personal history or ontogenic development (e.g., depression), the influences of those individuals with whom adolescents have immediate contact with, or the microsystems (e.g., family and school), the larger social units, or the exosystems, that indirectly influence adolescents (e.g., media), and the larger culture or macrosystems (e.g., cultural differences in attitudes about suicide). In this article the interaction of several factors within and between the permeable boundaries of each of the layers of the ecological paradigm is also highlighted. Finally, examples of intervention and prevention strategies at each level of the system are set forth. © 2002 Wiley Periodicals, Inc.
Recognition of protonated aliphatic α,ω‐diamines by coproporphyrin I tetraanion in water
Authors: Flores‐Villalobos Alejandro , Morales‐Rojas Hugo , Escalante‐Tovar Sigfrido , Yatsimirsky Anatoly K. 
Published: October 2002

AbstractInteractions of aliphatic α,ω‐diamines [H2N(CH2)
nNH2, 2 ≤ n ≤ 8] with coproporphyrin I tetraanion (CP) were studied by spectrophotometry, fluorimetry and 1H NMR spectroscopy in the pH range 7–10 and ionic strengths 0.01–0.1 M. Diprotonated diammonium cations induce dimerization of CP by forming 1:1 complexes with CP which undergo much stronger self‐aggregation than free CP tetraanions. On increasing the number of methylene units n connecting the ammonium groups, the binding constants for the complex formation with monomeric CP (KL) increase but the dimerization constants of the resulting complexes decrease. A hydrophobic contribution to the binding free energy of −1.6 ± 0.2 kJ mol−1 per methylene unit was obtained from the linear correlation of logKL values extrapolated to zero ionic strength vs the number of methylene units (n = 2–6). A model for diammonium‐induced porphyrin dimerization is proposed, which involves complexation of diammonium cations with CP monomer via a combination of electrostatic and hydrophobic interactions and subsequent formation of porphyrin face‐to‐face dimers in which diammonium cations serve as the stabilizing bridges via ion pairing to carboxylate groups of two CP monomeric units. Copyright © 2001 John Wiley & Sons, Ltd.
Kinetics and mechanism of the oxidation of substituted benzylamines by hexamethylenetetramine‐bromine
Authors: Dubey Rashmi , Kothari Seema , Banerji Kalyan K. 
Published: October 2002

AbstractThe oxidation of substituted benzylamines by hexamethylenetetramine‐bromine (HABR) to the corresponding aldimines is first order with respect to each the amine and HABR. It is proposed that HABR itself is the reactive oxidizing species. The oxidation of deuterated benzylamine (PhCD2NH2) indicated a substantial kinetic isotope effect (kH/kD = 5.60 at 293 K). This confirmed the cleavage of an α‐C—H bond in the rate‐determining step. Correlation analyses of the rates of oxidation of 20 monosubstituted benzylamines were performed with various single‐ and multi‐parametric equations. The rates of the oxidation showed excellent correlations in terms of the Yukawa–Tsuno and Brown equations. The polar reaction constants were negative. The oxidation exhibited extensive cross‐conjugation, in the transition state, between the electron‐donating substituents and the reaction centre. A mechanism involving a hydride ion transfer from the amine to HABR, in the rate‐determining step, is proposed. Copyright © 2001 John Wiley & Sons, Ltd.
Rate constants for the CH3O + NO → CH3ONO reaction by classical trajectory and canonical variational transition state theory calculations
Authors: Martínez‐Núñez Emilio , Borges Itamar , Vázquez S. A. 
Published: October 2002

AbstractClassical trajectory and canonical variational transition state theory (CVTST) calculations were performed on the CH3O + NO → CH3ONO recombination reaction for the temperature range 300–1000 K to study theoretically this reaction for the first time. The dynamics calculations employ our previously reported potential energy surface for the dissociation and elimination reactions of methyl nitrite (Martínez‐Núñez E, Vázquez SA. J. Chem. Phys. 1998; 109: 8907). In the present work this surface was conveniently modified to reproduce more accurately the experimental CH3ONO dissociation energy and to obtain more reliable rate constants for both the dissociation and the recombination reactions. The recombination rate constants calculated with this modified version of the original potential energy surface agree better with the experimental results than do the rates obtained with the original one. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanism and dynamics of organic reactions: 1,2‐H shift in methylchlorocarbene
Authors: Kraka Elfi , Cremer Dieter 
Published: October 2002

AbstractThe unified reaction valley approach (URVA) was used to investigate the mechanism of the rearrangement of methylchlorocarbene to chloroethene [reaction(1)] in the gas phase with special emphasis on the role of H tunneling. The reaction valley of (1) was explored using different methods (HF, MP2 and DFT/B3LYP) and different basis sets [6–31G(d), 6–31G(d,p) and cc‐pVTZ]. Results were analyzed characterizing normal modes, reaction path vector and curvature vector in terms of generalized adiabatic modes associated with internal parameters that are used to describe the reaction complex. For reaction (1), H tunneling plays a significant role even at room temperature, but does not explain the strongly curved Arrhenius correlations observed experimentally. The probability of H tunneling can be directly related to the curvature of the reaction path and the associated curvature couplings. The reaction is preceeded in the forward and reverse direction by energy‐consuming conformational changes that prepare the reactant for the actual 1,2‐H shift, which requires only little energy. The effective energy needed for CH bond breaking is just 6 kcal mol−1 for (1). The gas‐phase and the solution‐phase mechanisms of (1) differ considerably, which is reflected by the activation enthalpies: 11.4 (gas, calculated) and 4.3 kcal mol−1 (solution, measured). Stabilizing interactions with solvent molecules take place in the latter case and reduce the importance of H tunneling. The non‐linearity of the measured Arrhenius correlations most likely results from bimolecular reactions of the carbene becoming more important at lower temperatures. Copyright © 2002 John Wiley & Sons, Ltd.
Theoretical study of the ring‐opening reactions of 2H‐azirines—a classification of substituent effects
Authors: Klessinger Martin , Bornemann Christian 
Published: October 2002

AbstractBased on CASSCF and CASPT2 calculations, the mechanisms of the photoreactions of 2H‐azirines are discussed. A general classification of substituent effects on non‐adiabatic singlet photoreactions is presented, and the effect of phenyl substituents on the photochemistry of 2H‐azirine, including the wavelength dependence of the photochemistry of 3‐phenyl‐2H‐azirine, is discussed in detail. Copyright © 2002 John Wiley & Sons, Ltd.
4‐Alkylbenzopyrylium perchlorates as C—H Acidic compounds
Authors: Grummt U.‐W. , Czerney P. 
Published: October 2002

Abstract7‐Alkyl‐5,6‐dihydro‐3‐methoxy(naphtho[1,2b]‐1‐benzopyrylium) compounds are acidochromic due to CH acidity of the 7‐alkyl substituent. Their acidity exponents are 4 < pKa < 5 and 1 < pKa < 3 regardless of whether the carbocation generated by deprotonation is resonance stabilized by a phenyl substituent or not. The thermodynamic equilibrium data were obtained via UV–vis spectroscopy. The activation parameters for protonation and deprotonation reactions were derived from rapid mixing experiments. Ab initio calculations with model compounds are presented in order to rationalize the experimental findings. The title compounds are useful objects to study the kinetics of proton‐transfer kinetics to and from carbon. Copyright © 2002 John Wiley & Sons, Ltd.
Bivariate distribution in copolymers: A new model
Authors: Montaudo Maurizio S. , Adamus Grażyna , Kowalczuk Marek 
Published: October 2002

AbstractA new model for the bivariate distribution of chain sizes and composition in copolymers is presented. The model combines the sum of a two‐bivariate distribution, and it replaces the previous model that consists of a single entity. The compositional distribution histogram was obtained by summation of the sections of the bivariate distribution that belong to a narrow compositional range. The predictions of the model were compared with mass spectrometric data relative to a block copolymer sample containing structural units of pivalolactone and 3‐hydroxybutyrate with some literature data, namely, mass spectrometric data concerning a random copolymer sample reacted at high conversion containing units of styrene and methyl methacrylate as well as a block copolymer sample containing units of α‐methyl styrene and methyl methacrylate. The new model gives better results than the previous model because it fits better with the experimental compositional distribution histogram of the copolymer samples. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2442–2448, 2002