bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isotopic labelling in mass spectrometry as a tool for studying reaction mechanisms of ion dissociations
Authors: Holmes John L. , Jobst Karl J. , Terlouw Johan K. 
Published: June 2007

AbstractPerhaps the greatest influence that isotopic labelling experiments have had on organic mass spectrometry is that reaction mechanisms originally borrowed from the chemistry of neutral counterparts have proved to be inadequate for explaining the results. It was therefore necessary to devise completely new types of fragmentation mechanisms and unconventional structures for organic gas‐phase cations. In most cases the labelling technique allows one to discover the positions at which the label atoms are found in both the charged and neutral products of an ion's dissociation. These experimental results are often difficult to rationalize by any simple mechanism, but they nearly always indicate how chemical computations should be directed in order for the latter to be able to provide a better mechanistic understanding. This short article describes some significant studies involving D and 18‐O labelling that well support the above assertions, using as examples the behaviour of some quite simple organic molecules. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of cyclooxygenase‐2 overexpression on skin carcinogenesis is context dependent
Authors: Rundhaug Joyce E. , Pavone Amy , Kim Eunjung , Fischer Susan M. 
Published: June 2007

AbstractThe up‐regulation of the inducible form of cyclooxygenase (COX‐2), a central enzyme in the prostaglandin (PG) biosynthetic pathway, occurs in many epithelial tumors and has been associated with tumor cell proliferation and angiogenesis. To better understand the role of COX‐2 in skin tumor development, we generated transgenic mice that overexpress COX‐2 under the control of the keratin 14 promoter. We previously reported (Cancer Res. 62: 2516, 2002) that these mice, referred to as keratin 14 (K14).COX2 mice, were unexpectedly very resistant to 12‐O‐tetradecanoylphorbol 13‐acetate (TPA) tumor promotion. The current studies were undertaken to determine the mechanism of this resistance and determine if it was restricted to TPA promotion. Transgenic and wild‐type mice were subjected to a complete carcinogenesis protocol using 7,12‐dimethylbenz[a]anthracene (DMBA) only, as well as a two‐stage protocol using DMBA plus an unrelated tumor promoter, anthralin. In addition, the responses of transgenic and wild‐type mice to TPA in terms of induction of proliferation and various down‐stream mediators were examined. The TPA resistance phenotype correlated with a reduced ability to induce ornithine decarboxylase, interleukin‐1α, and tumor necrosis factor‐α and a reduced proliferation response. This resistance phenotype appears to be restricted to phorbol ester promotion because K14.COX2 mice developed six times more tumors than wild‐type mice when anthralin was used as the tumor promoter. Additionally, K14.COX2 mice treated only with DMBA developed approximately 3.5 times more tumors than wild‐type mice, suggesting that PGs have intrinsic tumor promoting activity. We conclude that the role of PGs in skin tumorigenesis is context dependent. © 2007 Wiley‐Liss, Inc.
A perspective on murine keratinocyte stem cells as targets of chemically induced skin cancer
Authors: Kangsamaksin Thaned , Park Heui Joon , Trempus Carol S. , Morris Rebecca J. 
Published: June 2007

AbstractAlthough ideas on the stem cell origins of cancer date more than one hundred years, critical evidence to support these theories is largely lacking. Our objective here is to outline our historical perspective on keratinocyte stem cells in the cutaneous epithelium and to summarize specific evidence suggesting that epithelial stem cells may contribute to chemically induced skin cancer. We note that, while strong evidence does support this hypothesis, experiments in progress may provide direct visualization of tumors derived from hair follicle stem cells. © 2007 Wiley‐Liss, Inc.
A computational approach for predicting the hydroelasticity of flexible structures based on the pressure Poisson equation
Authors: Liew K. M. , Wang W. Q. , Zhang L. X. , He X. Q. 
Published: June 2007

AbstractThis work is concerned with the modeling of the interaction of fluid flow with flexible solid structures. The flow under consideration is governed by the Navier–Stokes equations for incompressible viscous fluids and modeled with low‐order velocity–pressure finite elements. The motion of the fluid domain is accounted for by the arbitrary Lagrangian–Eulerian formulation. The structure is represented by means of an appropriate standard finite element formulation. The spring smooth analogy is used
to mesh control. The time integrating algorithm is based on the predictor–multi‐corrector algorithm. An important aspect of the present work is the introduction of a new monolithic approach based on the fluid pressure Poisson equation (PPE) to solve the hydroelasticity problem of an incompressible viscous fluid with an elastic body that is vibrating due to flow excitation. The PPE is derived to be consistent with the coupled system equation for the fluid–structure interaction (FSI). Based on this approach, an efficient monolithic method is adopted to simulate hydroelasticity between the flexible structure and the flow. The fluid pressure is implicitly derived to satisfy the incompressibility constraint, and the other unknown variables are explicitly derived. The coefficient matrix of the PPE for the FSI becomes symmetric and positive definite. To demonstrate the performance of the proposed approach, two working examples, a beam immersed in incompressible fluid and a guide vane of a Francis turbine passage, were used. The results show the validity of the proposed approach. Copyright © 2007 John Wiley & Sons, Ltd.
Leprosy at the Lazaretto on St Eustatius, Netherlands Antilles
Authors: Gilmore J. K. 
Published: June 2007

AbstractLeprosaria established in the Americas during the Colonial period bear many similarities with those found in medieval Europe. They are comparable in terms of isolation, the objectification of leprosy sufferers and their association with religious charities. The Lazaretto on St Eustatius was operated from 1866 to 1923. The site was investigated to recover palaeopathological evidence of leprosy at a leprosarium in the Americas. Five burials were excavated; three individuals showed evidence of bone modifications consistent with those caused by leprosy, including aspects of ‘rhinomaxillary syndrome’ and the bilaterally symmetrical post‐cranial changes that have been described in leprosy examples from medieval Europe. An exceptional find was the presence of potentially leprous bone changes to the hyoid, thyroid and 3rd–6th cervical vertebrae. Copyright © 2007 John Wiley & Sons, Ltd.
Tissue microarray‐based screening for chromosomal breakpoints affecting the T‐cell receptor gene loci in mature T‐cell lymphomas
Authors: Leich E , Haralambieva E , Zettl A , Chott A , Rüdiger T , Höller S , Müller‐Hermelink H‐K , Ott G , Rosenwald A 
Published: June 2007

AbstractThe pathogenesis of mature T‐cell non‐Hodgkin lymphomas (T‐NHLs) is poorly understood. Analogous to B‐cell lymphomas, in which the immunoglobulin (IgH) receptor loci are frequently targeted by chromosomal translocations, the T‐cell receptor (TCR) gene loci are affected by translocations in a subset of precursor T‐cell malignancies. In a large‐scale analysis of 245 paraffin‐embedded mature T‐NHLs, arranged in a tissue microarray format and using improved FISH assays for the detection of breakpoints in the TCRα/δ, TCRβ, and TCRγ loci, we provide evidence that mature T‐NHLs other than T‐cell prolymphocytic leukaemia (T‐PLL) also occasionally show a chromosomal rearrangement that involves the TCRα/δ locus. In particular, one peripheral T‐cell lymphoma (not otherwise specified, NOS) with the morphological variant of Lennert lymphoma displayed a chromosomal translocation t(14;19) involving the TCRα/δ and the BCL3 loci. A second case, an angio‐immunoblastic T‐cell lymphoma (AILT), carried an inv(14)(q11q32) affecting the TCRα/δ and IgH loci. FISH signal constellations as well as concomitant comparative genomic hybridization (CGH) data were also suggestive of the occurrence of an isochromosome 7, previously described to be pathognomonic for hepatosplenic T‐cell lymphomas, in rare cases of enteropathy‐type T‐cell lymphoma. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Altered claudin expression is a feature of chronic plaque psoriasis
Authors: Watson REB , Poddar R , Walker JM , McGuill I , Hoare LM , Griffiths CEM , O'Neill CA 
Published: June 2007

AbstractEpithelial tight junctions play a central role in cell–cell adhesion and are necessary for the selective paracellular movement of ions. Claudins are key components of tight junctions and their expression is altered in gut epithelia in a variety of inflammatory enteropathies, including ulcerative colitis and Crohn's disease. Psoriasis is a chronic inflammatory skin disease affecting approximately 2% of the western population, with significantly increased occurrence in individuals with Crohn's disease. Initial studies investigated the expression of claudins in skin of healthy volunteers and patients with chronic plaque psoriasis. We report here that claudins‐1 and ‐3 are the major protein species present in the epidermis of healthy skin; they are expressed on the surface of epidermal keratinocytes, consistent with their localization to tight junctions. In plaques of psoriasis, claudin‐1 was not identifiable in the epidermis, although typical staining patterns were observed in clinically normal, uninvolved skin of patients with psoriasis. Claudin‐3 was present in the epidermal granular cell layer in normal skin, but was only identified within the cytosol of epidermal keratinocytes in both involved and uninvolved skin of psoriasis patients. We examined further whether exposure of keratinocytes in vitro to pro‐inflammatory cytokines mimicked the observed changes in claudin expression seen in chronic plaque psoriasis; lipopolysaccharide, interferon‐γ and tumour necrosis factor‐α had no effect on claudin protein expression or distribution. Addition of interleukin‐1β, however, resulted in down‐regulation of claudins‐1 and ‐3. Tumour necrosis factor‐α and interleukin‐1β were further used in an in vivo model of skin inflammation; interleukin‐1β alone modulated claudin protein expression in this system. These data demonstrate that epidermal claudin expression is altered in chronic plaque psoriasis and that expression is in part modulated by interleukin‐1β. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Alagille syndrome and nephroblastoma: Unusual coincidence of two rare disorders
Authors: Bourdeaut Franck , Guiochon‐Mantel Anne , Fabre Monique , Martelli Hélène , Patte Catherine , Porta Gilda , Bernard Olivier , Delattre Olivier , Jacquemin Emmanuel 
Published: June 2007

AbstractAlagille syndrome is a rare developmental disorder combining bile duct paucity, congenital cardiopathy, facial dysmorphy, vertebrae defects, and ocular abnormalities, and frequent renal abnormalities. It does not usually predispose to malignancies. Nephroblastoma has been observed in many developmental disorders, but never in Alagille syndrome. We report two original cases of nephroblastoma associated to Alagille syndrome. We identified a new V136G JAG1 missense mutation in one patient and a constitutional deletion of 20p12 in the other. In one nephroblastoma an additional somatic 1p36 deletion was present. The link between Alagille syndrome, JAG1 alterations and nephroblastoma is discussed. Pediatr Blood Cancer 2008;50:908–911. © 2007 Wiley‐Liss, Inc.
A molecular classification of congenital neutropenia syndromes
Authors: Boxer Laurence A. , Newburger Peter E. 
Published: June 2007

AbstractCurrent knowledge on the molecular pathogenesis of severe congenital neutropenia indicates that the clinical diagnosis includes a heterogeneous group of disorders following different patterns of inheritance. Similarly, multifaceted syndromes associated with neutropenia can be classified molecularly, which in turn allows for a better understanding of the basis of the neutropenia. Many of the neutropenia disorders can be treated with G‐CSF (filgrastim) to increase the neutrophil count, thereby reducing infection morbidity and mortality. In some instances hematopoietic stem cell transplantation remains the only curative treatment currently available. This review describes and classifies, on a molecular basis, both primary congenital neutropenia and multifaceted syndromes associated with neutropenia. Pediatr Blood Cancer 2007;49:609–614. © 2007 Wiley‐Liss, Inc.
Long‐term complications and quality of life in children with intraspinal tumors
Authors: Poretti Andrea , Zehnder Daniel , Boltshauser Eugen , Grotzer Michael A. 
Published: June 2007

AbstractBackgroundSpinal cord compression by pediatric intraspinal tumors may result in persisting neurological deficits. The impact such late effects have on social and psychological adjustment and quality of life has not been documented previously.MethodTo study the long‐term outcome of pediatric patients with intraspinal tumors, we followed 28 consecutive patients under 16 years of age who were treated in a single institution from 1975 to 2005. In 20 of 26 survivors (median follow‐up time 8.4 years, range 0.8–31.3 years) who agreed to participate, neurological, orthopedic, and cognitive complications and their impact on behavioral and psychological adjustment, and health‐related quality of life (HRQoL) were comprehensively assessed qualitatively and quantitatively. Primary therapy for spinal cord decompression was surgery in ten patients, chemotherapy in nine, and radiotherapy in one.ResultsTumor control was good (10‐year overall survival rate of 96%; 10‐year progression‐free survival rate of 84%). Persistent neurological complications occurred in 10 (50%) patients (paraparesis, n = 7; monoparesis, n = 3; neurogenic bladder dysfunction, n = 4; neurogenic bowel dysfunction, n = 2). Two of the ten patients with paresis depended on wheelchair. Seven (35%) patients developed scoliosis and six of these required spondylodesis. Survivors reported no major impairments in daily activities and rated their HRQoL only slightly lower than healthy controls. The only statistically significant difference was in emotional functioning.DiscussionMost patients with intraspinal tumors have a good chance of cure. Apart from few patients, especially those with severe neurological complications, self‐rated HRQoL is comparable to that of healthy controls. Pediatr Blood Cancer 2008;50:844–848. © 2007 Wiley‐Liss, Inc.
Degradative chain transfer in vinyl acetate polymerizations using toluene as solvent
Authors: Lonsdale Daria E. , Johnston‐Hall Geoffrey , Fawcett Amanda , Bell Craig A. , Urbani Carl N. , Whittaker Michael R. , Monteiro Michael J. 
Published: June 2007

AbstractIn this work, we propose that retardation in vinyl acetate polymerization rate in the presence of toluene is due to degradative chain transfer. The transfer constant to toluene (Ctrs) determined using the Mayo method is equal to 3.8 × 10−3, which is remarkably similar to the value calculated from the rate data, assuming degradative chain transfer (2.7 × 10−3). Simulations, including chain‐length‐dependent termination, were carried out to compare our degradative chain transfer model with experimental results. The conversion–time profiles showed excellent agreement between experiment and simulation. Good agreement was found for the Mn data as a function of conversion. The experimental and simulation data strongly support the postulate that degradative chain transfer is the dominant kinetic mechanism. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3620–3625, 2007
Synthesis and properties of novel regioirregular polyimides from easily synthesized asymmetrical dichlorophthalimide monomers
Authors: Li Wenmu , Chen Guang , Zhang Suobo , Wang He , Yan Donghang 
Published: June 2007

AbstractNew asymmetrical aromatic dichlorophthalimide monomers containing pendant groups (trifluoromethyl or methyl) were conveniently prepared from inexpensive and commercially available compounds. With these monomers, a new class of soluble polyimides with a regioirregular structure within the polymer backbone was obtained by the Ni(0)‐catalyzed polymerization method. The structures of the polymers were confirmed by various spectroscopic techniques. The polyimides displayed better solubility and higher thermal stability than the corresponding regular polyimides. In addition, fluorinated polyimides in this study had low dielectric constants ranging from 2.52 to 2.78, low moisture absorptions of less than 0.59%, and low thermal expansion coefficients between 10.6 and 19.7 ppm/°C. The oxygen permeability coefficients and permeability selectivity of oxygen to nitrogen of the films were in the ranges of 2.99–4.20 barrer and 5.55–7.50, respectively. We have demonstrated that the synthetic pathway for polyimides provides a successful approach to increasing the solubility and processability of polyimides without sacrificing their thermal stability. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3550–3561, 2007
Synthesis of ethylene‐1‐hexene copolymers from ethylene stock by tandem action of bis(2‐dodecylsulfanyl‐ethyl) amine‐CrCl3 and Et(Ind)2ZrCl2
Authors: Zhang Junwei , Li Bo‐Geng , Fan Hong , Zhu Shiping 
Published: June 2007

AbstractIn this work, ethylene‐1‐hexene copolymers were synthesized with a tandem catalysis system that consisted of a new trimerization catalyst bis(2‐dodecylsulfanyl‐ethyl) amine‐CrCl3/MAO (1/MAO) and copolymerization catalyst Et(Ind)2ZrCl2/MAO (2/MAO) at atmosphere pressure. Catalyst 1 trimerized ethylene with high activity and excellent selectivity in the presence of a relatively low amount of MAO. Catalyst 2 incorporated the 1‐hexene content and produced ethylene‐1‐hexene copolymer from an ethylene‐only stock in the same reactor. Adjusting the Cr/Zr ratio and reaction temperature yielded various branching densities and thus melting temperatures. However, broad DSC curves were observed when low temperatures and/or high Cr/Zr ratios were employed due to an accumulation of 1‐hexene component and composition drifting during the copolymerization. It was found that a short pretrimerization period resulted in more homogeneous materials that gave unimodal DSC curves. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3562–3569, 2007
One‐pot preparation of 3‐miktoarm star terpolymers via click [3 + 2] reaction
Authors: Altintas Ozcan , Yankul Burcu , Hizal Gurkan , Tunca Umit 
Published: June 2007

AbstractThe preparation of 3‐miktoarm star terpolymers using nitroxide mediated radical polymerization (NMP), ring opening polymerization (ROP), and click reaction [3 + 2] are carried out by applying two types of one‐pot technique. In the first one‐pot technique, NMP of styrene (St), ROP of ε‐caprolactone (ε‐CL), and [3 + 2] click reaction (between azide end‐functionalized poly(ethylene glycol) (PEG‐N3)/or azide end‐functionalized poly(methyl methacrylate) (PMMA‐N3) and alkyne) are carried out in the presence of 2‐(hydroxymethyl)‐2‐methyl‐3‐oxo‐3‐(2‐phenyl‐2‐(2,2,6,6‐tetramethylpiperidin‐1‐yloxy)ethoxy) propyl pent‐4‐ynoate, 2, as an initiator for 48 h at 125 °C (one‐pot/one‐step). As a second technique, NMP of St and ROP of ε‐CL were conducted using 2 as an initiator for 20 h at 125 °C, and subsequently PEG‐N3 or azide end‐functionalized poly(tert‐butyl acrylate (PtBA‐N3) was added to the polymerization mixture, followed by a click reaction [3 + 2] for 24 h at room temperature (one‐pot/two‐step). The 3‐miktoarm star terpolymers, PEG‐poly(ε‐caprolactone)(PCL)‐PS, PtBA‐PCL‐PS and PMMA‐PCL‐PS, were recovered by a simple precipitation in methanol without further purification. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3588–3598, 2007
Photopolymerization reactions initiated by a visible light photoinitiating system: Cyanine dye/borate salt/1,3,5‐triazine
Authors: Kabatc Janina , Zasada Magdalena , Pączkowski Jerzy 
Published: June 2007

AbstractNew three‐component photoinitiating systems consisting of a cyanine dye, borate salt, and a 1,3,5‐triazine derivative were investigated by measuring their photoinitiation activities and through fluorescence quenching experiments. Polymerization kinetic studies based on the microcalorimetric method revealed a significant increase in polymerization rate when the concentration of n‐butyltriphenylborate salt or the 1,3,5‐triazine derivative were increased. The photo‐induced electron transfer process between electron donor and electron acceptor was studied by means of fluorescence quenching and SrEt change of the fluorescence intensity. The experiments performed documented that an increase of the n‐butyltriphenylborate salt concentration dramatically increases the rate of dye fluorescence quenching, whereas the increasing of the 1,3,5‐triazine derivative concentration slows down the consumption of the dye. We conclude that the primary photochemical reaction involves an electron transfer from the n‐butyltriphenylborate anion to the excited singlet state of the dye, followed by the reaction of the 1,3,5‐triazine derivative with the resulting dye radical to regenerate the original dye. This reaction simultaneously produces a triazinyl radical anion derived from the 1,3,5‐triazine, which undergoes the carbon‐halogen bond cleavage yielding radicals active in initiation of a free radical polymerization chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3626–3636, 2007
Synthesis and reactivity of allyl nickel(II) N‐heterocyclic carbene enolate complexes
Authors: Benson Stefan , Payne Bridgett , Waymouth Robert M. 
Published: June 2007

AbstractTwo new N‐heterocyclic carbene enolate nickel(II) allyl complexes have been prepared and their activity towards ethylene polymerization was investigated. It was found that in the presence of diethyl zinc, the carbene enolate complex bearing a nitro substituent produces highly linear polyethylene of modest molecular weight and high polydispersity. The influence of the reaction parameters on catalytic activity and the characteristics of the resulting polymer were investigated through systematic variation of the time, temperature, and diethyl zinc concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:3637–3647, 2007
Resolving Concentrated Particle Size Mixtures Using Dynamic Light Scattering
Authors: Kaszuba Michael , Connah Malcolm T. , McNeil‐Watson Fraser K. , Nobbmann Ulf 
Published: June 2007

AbstractDynamic light scattering (DLS) is a technique used for measuring the size of molecules and particles undergoing Brownian motion by observing time‐dependent fluctuations in the intensity of scattered light. The measurement of samples using conventional DLS instrumentation is limited to low concentrations due to the onset of a phenomenon called multiple scattering. The problems of multiple scattering have been addressed in a light scattering instrument incorporating non‐ invasive backscatter optics (NIBS). This novel optic arrangement maximizes the detection of scattered light while maintaining signal quality and allows for measurements of turbid samples. This paper discusses the ability of backscatter detection to accurately determine particle sizes at 1 %w/v sample concentrations and demonstrates the correct resolution of different size populations using a series of latex standard mixtures with known volume ratios. The concentration of 1 %w/v is much higher than can be measured on conventional dynamic light scattering instruments.