bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of electrochemical impedance spectroscopy to evaluate resin‐dentin bonds
Authors: Sword Jeremy , Pashley David H. , Foulger Stephen , Tay Franklin R. , Rodgers Robert 
Published: August 2007

AbstractElectrochemical impedance spectroscopy (EIS) offers a potentially nondestructive quantitative method for measuring the stability of resin films and or resin‐bonded dentin over time. The purpose of this study was to measure the electrical impedance of five experimental dental adhesives of increasing hydrophicities as 30‐μm films and as resin‐bonded coatings on acid‐etched dentin. Resin films or resin‐coated dentin disks were placed in U‐shaped chambers containing pairs of Ag–AgCl electrodes in 0.1M KCl. Electrical impedance spectra were run at day 0, 1, 7, 14, and 21 days. All resin films and resin‐bonded dentin showed increases in capacitance during the first day of storage in electrolyte. This was usually associated with an increase in the pore resistance of the resins. Generally, resin‐bonded dentin gave lower impedance values than their respective resins (resins 1–4) but solvated resin 5 bonded to water‐saturated dentin gave higher capacitance and impedance values than resin 5 films. However, solvated resin 5 films gave higher impedance values than resin 5‐bonded dentin. This behavior was confirmed by TEM examinations of silver uptake into films of neat resin 5 vs. ethanol‐solvated resin 5, where water tree‐like structures seen in the former were not seen in the latter. EIS is useful in examining changes in the capacitance and electrical impedance of very hydrophilic, ionic methacrylate resins. Its utility in detecting degradation in resin‐bonded dentin interfaces remains to be determined in longer term studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
An insight into the environmental effects of the pocket of the active site of the enzyme. Ab initio ONIOM‐molecular dynamics (MD) study on cytosine deaminase
Authors: Matsubara Toshiaki , Dupuis Michel , Aida Misako 
Published: July 2007

AbstractWe applied the ONIOM‐molecular dynamics (MD) method to cytosine deaminase to examine the environmental effects of the amino acid residues in the pocket of the active site on the substrate taking account of their thermal motion. The ab initio ONIOM‐MD simulations show that the substrate uracil is strongly perturbed by the amino acid residue Ile33, which sandwiches the uracil with His62, through the steric contact due to the thermal motion. As a result, the magnitude of the thermal oscillation of the potential energy and structure of the substrate uracil significantly increases. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
An approximate diatomics in molecules formulation of generalized valence bond theory
Authors: Cullen John 
Published: July 2007

AbstractThe slow computational speed of the generalized valence bond perfect pairing method (GVB‐PP) has been an impediment to its routine use. We have addressed this problem by employing a diatomics in molecules Hamiltonian derived from a second quantization perturbation approach. This results in all three‐ and four‐centered two‐electron integrals being dropped from the traditional GVB‐PP calculation. For moderate sized molecules, as for example C20 computed with a double zeta + polarization basis, there is on average a fifty‐fold decrease in computational times. In this article, we present the theory behind our approach and analyze the accuracy and speed of this approximate GVB‐PP method for several cases where density functional methods have produced ambivalent results. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Theoretical studies on four‐membered ring compounds with NF2, ONO2, N3, and NO2 groups
Authors: Fan Xiao‐Wei , Ju Xue‐Hai 
Published: July 2007

AbstractDensity functional theory (DFT) method has been employed to study the geometric and electronic structures of a series of four‐membered ring compounds at the B3LYP/6‐311G** and the B3P86/6‐311G** levels. In the isodesmic reactions designed for the computation of heats of formation (HOFs), 3,3‐dimethyl‐oxetane, azetidine, and cyclobutane were chosen as reference compounds. The HOFs for N3 substituted derivations are larger than those of oxetane compounds with ONO2 and/or NF2 substituent groups. The HOFs for oxetane with ONO2 and/or NF2 substituent groups are negative, while the HOFs for N3 substituted derivations are positive. For azetidine compounds, the substituent groups within the azetidine ring affect the HOFs, which increase as the difluoroamino group being replaced by the nitro group. The magnitudes of intramolecular group interactions were predicted through the disproportionation energies. The strain energy (SE) for the title compounds has been calculated using homodesmotic reactions. For azetidine compounds, the NF2 group connecting N atom in the ring decrease the SE of title compounds. Thermal stability were evaluated via bond dissociation energies (BDE) at the UB3LYP/6‐311G** level. For the oxetane compounds, the ONO2 bond is easier to break than that of the ring CC bond. For the azetidine and cyclobutane compounds, the homolysises of CNX2 and/or NNX2 (X = O, F) bonds are primary step for bond dissociation. Detonation properties of the title compounds were evaluated by using the Kamlet–Jacobs equation based on the calculated densities and HOFs. It is found that 1,1‐dinitro‐3,3‐bis(difluoroamino)‐cyclobutane, with predicted density of ca. 1.9 g/cm3, detonation velocity (D) over 9 km/s, and detonation pressure (P) of 41 GPa that are lager than those of TNAZ, is expected to be a novel candidate of high energy density materials (HEDMs). The detonation data of nitro‐BDFAA and TNCB are also close to the requirements for HEDMs. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Carbon assimilation and dissimilation during growth of Geotrichum candidum on amino acids and glucose
Authors: Aziza Majda , Amrane Abdeltif 
Published: July 2007

AbstractBACKGROUND: This work examines the metabolic behaviour of amino acids during Geotrichum candidum growth, in the presence of a primary carbon source like glucose. Amino acids were characterized based on their carbon assimilation and dissimilation by G. candidum, in the presence of glucose as the limiting substrate.RESULTS: The first group (Cys, His, Phe, Thr and Trp) was only used as nitrogen sources by G. candidum, with glucose being the carbon and energy source. Glucose repression was shown for the rest of the amino acids, since only after glucose depletion amino acids from the second group (Gly, Lys, Met, Val) were dissimilated for energy supply by oxidation into CO2, while those from the third group (Ala, Arg, Asp, Glu, Leu, Pro and Ser) were assimilated as carbon sources (and additionally used as nitrogen sources), leading to a diauxic growth.CONCLUSION: This energy‐saving response was not previously shown for the second fungus involved in ripening of soft white cheese—P. camembertii—leading to simultaneous use of some amino acids and glucose as carbon and energy sources, and hence lower growth rates than those recorded during G. candidum growth. Copyright © 2007 Society of Chemical Industry
Prenatal diagnosis of complete atrioventricular canal associated with tetralogy of Fallot
Authors: Hung Jeng‐Hsiu , Lu Jen‐Her , Hung Chia‐Yi Selena 
Published: July 2007

AbstractA complete atrioventricular canal defect occurs when an embryonic common atrioventricular valve fails to divide completely into 2 common atrioventricular valves. Tetralogy of Fallot is an abnormal embryologic development in which an unequal conotruncal division results in a small pulmonary artery and a large aortic artery. We report a case of prenatal diagnosis of a complete atrioventricular canal defect associated with tetralogy of Fallot. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008
Synthesis and analysis of [3H] salmon calcitonin ([3H]SMC021)
Authors: Ciszewska Grazyna , Allentoff Alban , Wu Amy , Ray Tapan 
Published: July 2007

AbstractTritium‐labelled salmon calcitonin was synthesized successfully through a 5 step peptide synthesis. LC‐MS performed on each step played an important role for in process control. For accuracy, Q‐TOF MS was used to determine the specific activity of tritiated salmon calcitonin ([3H]SMC021) using the triple charged ion. Copyright © 2007 John Wiley & Sons, Ltd.
SPECT imaging of the α4β2 nicotinic receptor using [5‐123I]A85380
Authors: Pimlott Sally L. , Piggott Margaret , Patterson James , Cavanagh Jonathan , Wyper David J. 
Published: July 2007

AbstractIn order to image nAChR density in vivo in humans, [5‐123I]‐iodo‐3‐[2(S)‐2‐azetidinylmethoxy]pyridine ([5‐123I]A85380) has been developed as a SPECT imaging tracer. This article outlines the radiochemical synthesis, in vitro validation in human post‐mortem tissue and some initial in vivo clinical studies using the ligand [5‐123/125I]A85380. Limitations of the usefulness of the tracer for routine clinical use are also discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of the myoview™ ligand, [bisphosphinoethane‐1,2‐14C]tetrofosmin
Authors: Woolley Geoffrey T. , Kitson Sean L. , Gordon Reid R. 
Published: July 2007

AbstractThe carbon‐14 radiolabels in [bisphosphinoethane‐1,2‐14C]tetrofosmin ligand were readily introduced by reacting 1,2‐dibromo[U‐14C]ethane with bis(2‐ethoxyethyl)benzylphosphine (1). This was converted to the Myoview™ ligand in an overall yield of 45%. This radiosynthesis was important in obtaining marketing approval from the regulatory authorities and allowed Myoview™ to become one of the main heart imaging agents of today. Copyright © 2007 John Wiley & Sons, Ltd.
Isotopic enrichment enhancement in metabonomic analysis of UPLC–MS data sets
Authors: Athersuch Toby J. , Nicholson Jeremy K. , Wilson Ian D. 
Published: July 2007

AbstractIsotopic enrichment of compounds dosed in drug metabolism studies greatly enhances the spectroscopic differentiation of xenobiotic and endogenous metabolites. We show the application of13C15N labelling of a model drug (4‐cyanoaniline) as an aid to metabonomic studies of UPLC–MS‐generated metabolic data sets. Copyright © 2007 John Wiley & Sons, Ltd.
Tritium‐labelling via an iridium‐based solid‐phase catalyst
Authors: Hickey Michael J. , Kingston Lee P. , Lockley William J. S. , Allen Paul , Mather Andrew , Wilkinson David. J. 
Published: July 2007

AbstractA solid‐phase, iridium‐based ortho‐exchange catalyst has been developed, with the aim of producing cleaner, more efficient, systems for tritium and deuterium labelling. The catalyst, which is a solvated polystyrene‐bound triphenylphosphine complex of cyclooctadienyliridium(I) hexafluorophosphate, was evaluated with respect to more conventional catalysts such as CODIr(PPh3)2PF6 and the Crabtree catalyst using simple model compounds as substrates. Labelling of drug candidate molecules proceeds with high regioselectivity and, after a simple filtration step, affords products with high radiochemical purities directly from the exchange reaction. The solid‐phase catalyst functioned well with a variety of traditional directing groups including nitro, amide, benzophenone and N‐heterocycles. Copyright © 2007 John Wiley & Sons, Ltd.
The risks of exposure to internal emitters
Authors: Wakeford Richard 
Published: July 2007

AbstractThe risks to health from internally deposited radionuclides have received considerable attention in recent years. There are significant issues concerned with exposure to internal emitters beyond those associated with the risks posed by external sources of penetrating ionizing radiations, and these issues lead to additional uncertainty in risk estimates pertaining to internal emitters. There is, however, no firm evidence that the risks from internally deposited radioactive material have been seriously underestimated by scientific review groups, but the uncertainties associated with the risks of exposure to internal emitters need to be taken into account in radiological protection. Copyright © 2007 John Wiley & Sons, Ltd.
Towards stereoselective radiosynthesis of α‐[11C]methyl‐substituted aromatic α‐amino acids – a challenge of creation of quaternary asymmetric centre in a very short time
Authors: Popkov Alexander , Nádvorník Milan , Kružberská Pavla , Lyčka Antonín , Lehel Szabolcs , Gillings Nicholas 
Published: July 2007

AbstractIn positron emission tomography (PET) α‐methyl amino acids have two potential applications: As analogues of neutransmitter precursors for the study of neurodegenerative diseases; as non‐metabolised analogues of proteinogenic amino acids for the study of amino acid uptake into normal and cancer cells.Clinical applications of such amino acids are strongly limited due to their poor availability. We carried out [11C]methylation of metalocomplex synthons derived from protected DOPA or tyrosine. For [11C]methylation, sodium hydroxide (5 mg of fine dry powder) was sealed in a vial, which was flushed with dry nitrogen before addition of a solution of the complex (10 mg) and 11CH3I in 1,3‐dimethylimidazolidin‐2‐one (300 µl). After 10 min at 25°C, a 9% radiochemical yield (decay‐corrected) of a mixture of the diastereomeric α‐[11C]methylDOPA complexes or a 7% radiochemical yield of a mixture of the diastereomeric α‐[11C]methyltyrosine complexes was achieved. Individual diastereomers were successfully separated by preparative HPLC, diluted with excess of water and extracted on C18 cartridges. Optimisation of the procedure including hydrolysis of the complexes (hydrolytic deprotection of enantiomerically pure amino acids) and subsequent purification of the enantiomers of α‐[11C]methylDOPA and α‐[11C]methyltyrosine is underway. Copyright © 2007 John Wiley & Sons, Ltd.
Opportunities for isotopic labelling via phase‐tagged synthesis with organogermanium linkers
Authors: Spivey Alan C. , Martin Laetitia J. , Noban Catherine , Jones Teyrnon C. , Ellames George J. , Kohler Andrew D. 
Published: July 2007

AbstractStrategies for the use of germanium‐based linkers for the phase‐tagged synthesis of isotopically labelled intermediates are described. Protocols of potential use in the devolatilization of volatile intermediates prepared from [14C]‐CO2 and [14C]‐PhBr to aid ADME studies on drug substances and their metabolites are discussed in relation to SR47035 (an advanced intermediate en‐route to the 5‐HT2 receptor antagonist SR46349B) and 4‐amino‐4‐phenylpiperidine (a key intermediate in the synthesis of NK3 receptor antagonist SR142801, osanetant). Additionally, protocols with potential for the preparation of [123I] and [18F]‐labelled SPECT/PET imaging/diagnostic agents are discussed in relation to an [123I]‐labelled analogue of SR141716 (rimonabant, a CB1 receptor antagonist) and 6‐[18F]‐(S)‐DOPA (for diagnosis of Parkinson's disease). Copyright © 2007 John Wiley & Sons, Ltd.
Production of radioisotopes in the BR2 high‐flux reactor for applications in nuclear medicine and industry
Authors: Ponsard Bernard 
Published: July 2007

AbstractThe BR2 reactor, put into operation in 1963 and refurbished in 1995–1997, is a 100 MW high‐flux ‘materials testing reactor’ which provides thermal neutron fluxes up to 1015 n/cm2 s. The production of radioisotopes, characterized by high specific activities, is carried out in dedicated in‐core devices within standard irradiation cycles of 3–4 weeks and in accordance with a ‘quality system’ that has been certified to the requirements of the ‘EN ISO 9001:2000’ in November 2003. Due to its operating flexibility, its reliability and its production capacity, the BR2 reactor is considered as a major facility for a routine supply of radioisotopes such as 99Mo (99mTc), 131I, 133Xe, 192Ir, 186Re, 153Sm, 169Er, 90Y, 32P, 188W (188Re), 203Hg, 82Br, 79Kr, 41Ar, 125I, 177Lu, 89Sr, 60Co, 169Yb, 147Nd, etc. It will continue to play this key role with the possibility of an extra operating cycle from 2006 and the realization of various ‘test’ irradiations to develop the production of new radioisotopes. Some irradiation devices allow the loading and unloading of irradiated targets during the operation of the reactor. Hot cells and storage facilities are available to prepare and organize the shipment of the irradiated targets to dedicated processing facilities. Copyright © 2007 John Wiley & Sons, Ltd.
The use of biocatalysis in the synthesis of labelled compounds
Authors: Allen John , Brasseur Denis M. , De Bruin Béatrice , Denoux Mireille , Pérard Serge , Philippe Nicolas , Roy Sébastien N. 
Published: July 2007

AbstractSince most biotransformations are highly chemo‐, regio‐ and stereoselective, they offer many opportunities for the synthesis of compounds that are not easily attainable by classical organic chemistry, The catalytic properties of the cytochrome P450 (CYP450) enzymes of microorganisms can be exploited to produce suitable N‐, S‐ or O‐dealkylated precursors, which can be realkylated with the appropriate labelled reagent. These enzymes are also well reported for hydroxylation of activated or nonactivated carbon centres, to produce drug metabolites. Nevertheless, to use such enzymes, a whole cell system is preferred due to the need for cofactor regeneration. Nitrile hydrolysing enzymes also attract attention, due to their ability to selectively hydrolyse nitrile derivatives under mild conditions. The scope of such biotransformations is discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Long‐term exposure to dieldrin reduces γ‐aminobutyric acid type A and N‐methyl‐D‐aspartate receptor function in primary cultures of mouse cerebellar granule cells
Authors: Babot Zoila , Vilaró M. Teresa , Suñol Cristina 
Published: July 2007

AbstractThe organochlorine pesticide dieldrin is a persistent organic pollutant that accumulates in the fatty tissue of living organisms. In mammals, it antagonizes the GABAA receptor, producing convulsions after acute exposure. Although accumulation in human brain has been reported, little is known about the effects of long‐term exposure to dieldrin in the nervous system. Homeostatic control of the balance between excitation and inhibition has been reported when neuronal activity is chronically altered. We hypothesized that noncytotoxic concentrations of dieldrin could decrease glutamatergic neurotransmission as a consequence of a prolonged reduction in GABAA receptor function. Long‐term exposure of primary cerebellar granule cell cultures to 3 μM dieldrin reduced the GABAA receptor function to 55% of control, as measured by the GABA‐induced 36Cl− uptake. This exposure produced a significant reduction (∼35%) of the NMDA‐induced increase in [Ca2+]i and of the [3H]MK‐801 binding, which was not accompanied by a reduction in the NMDA receptor subunit NR1, as determined by Western blot. Consistent with the decreased NMDA receptor function, dieldrin‐treated cultures were insensitive to an excitotoxic stimulus induced by exposure to high potassium. In summary, we report that the chronic reduction of GABAA receptor function induced by dieldrin decreases the number of functional NMDA receptors, which may be attributable to a mechanism of synaptic scaling. These effects could underlie neural mechanisms involved in cognitive impairment produced by low‐level exposure to dieldrin. © 2007 Wiley‐Liss, Inc.
In vitro neural injury model for optimization of tissue‐engineered constructs
Authors: Cullen D. Kacy , Stabenfeldt Sarah E. , Simon Crystal M. , Tate Ciara C. , LaPlaca Michelle C. 
Published: August 2007

AbstractStem cell transplantation is a promising approach for the treatment of traumatic brain injury, although the therapeutic benefits are limited by a high degree of donor cell death. Tissue engineering is a strategy to improve donor cell survival by providing structural and adhesive support. However, optimization prior to clinical implementation requires expensive and time‐consuming in vivo studies. Accordingly, we have developed a three‐dimensional (3‐D) in vitro model of the injured host–transplant interface that can be used as a test bed for high‐throughput evaluation of tissue‐engineered strategies. The neuronal‐astrocytic cocultures in 3‐D were subjected to mechanical loading (inducing cell death and specific astrogliotic alterations) or to treatment with transforming growth factor‐β1 (TGF‐β1), inducing astrogliosis without affecting viability. Neural stem cells (NSCs) were then delivered to the cocultures. A sharp increase in the number of TUNEL+ donor cells was observed in the injured cocultures compared to that in the TGF‐β1‐treated and control cocultures, suggesting that factors related to mechanical injury, but not strictly astrogliosis, were detrimental to donor cell survival. We then utilized the mechanically injured cocultures to evaluate a methylcellulose‐laminin (MC‐LN) scaffold designed to reduce apoptosis. When NSCs were codelivered with MC alone or MC‐LN to the injured cocultures, the number of caspase+ donor cells significantly decreased compared to that with vehicle delivery (medium). Collectively, these results demonstrate the utility of an in vitro model as a preanimal test bed and support further investigation of a tissue‐engineering approach for chaperoned NSC delivery targeted to improve donor cell survival in neural transplantation. © 2007 Wiley‐Liss, Inc.
Regulation of membrane association and kinase activity of Cdk5–p35 by phosphorylation of p35
Authors: Sato Ko , Zhu Ying‐Shan , Saito Taro , Yotsumoto Kensuke , Asada Akiko , Hasegawa Masato , Hisanaga Shin‐ichi 
Published: August 2007

AbstractAlthough protein kinase Cdk5–p35 is important in many aspects of the development and function of the central nervous system, relatively little is known about its regulation. In the present study, we examined the relationship between the association of this kinase with membranes and its activity in perinatal and adult rat brains. Cdk5–p35 in perinatal brain exhibited higher activity than that found in adult tissue. Gel filtration chromatography revealed that a portion of Cdk5–p35 from fetal brain occurred as a soluble complex, whereas Cdk5–p35 in adult brain occurred predominantly as a membrane‐bound complex. Furthermore, soluble Cdk5–p35 in perinatal brain displayed elevated kinase activity, whereas membrane‐bound Cdk5–p35 was highly active only in the presence of detergent. This more active soluble form of Cdk5–p35 correlated to a form in which p35 was phosphorylated, whereas the less active membrane‐bound form of Cdk5 correlated to the dephosphorylated form of p35, as evidenced by a downward shift in electrophoretic mobility. Cdk5 activity and transition from soluble to membrane‐associated compartments could be modulated by conditions that affected the phosphorylation or dephosphorylation of p35. For example, dephosphorylation of p35 in brain extracts was suppressed by selective inhibition of protein phosphatase‐1. Together, these results suggest that the kinase activity of Cdk5–p35 is regulated through its association with membranes, which in turn is under the control of Cdk5‐dependent phosphorylation and protein phosphatase‐1–dependent dephosphorylation of p35. © 2007 Wiley‐Liss, Inc.