bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and chain extension of poly(L‐lactic acid‐co‐succinic acid‐co‐1,4‐butene diol)
Authors: Lee Choon Mee , Kim Hun Sik , Yoon Jin San 
Published: January 2005

AbstractL‐Lactic acid (LA) was copolymerized with succinic acid (SA) and 1,4‐butenediol (1,4‐BED) in bulk state with titanium(IV) butoxide as a catalyst to produce poly(LA‐co‐SA‐co‐1,4‐BED) (PLASBED). Poly(L‐lactic acid) (PLLA) homopolymer obtained from a direct condensation polymerization of LA had weight average molecular weight (Mw) less than 4.1 × 104 and was too brittle to prepare specimens for the tensile test. Addition of SA and 1,4‐BED to LA produced PLASB with Mw as high as 1.4 × 105 and exhibited tensile properties comparable to a commercially available high‐molecular‐weight PLLA. Chain extension by intermolecular linking reaction through the unsaturated 1,4‐BED units in PLASBED with benzoyl peroxide further increased the molecular weight and made PLASBED more ductile and flexible to show elongation at break as high as 450%. Biodegradability of PLASBED measured by the modified Sturm test was nearly independent of the 1,4‐BED content. Gel formation during the chain extension did not exert any significant influence on the biodegradability either. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1116–1121, 2005
CYP2D6 and CYP1A1 mutations in the Turkish population
Authors: Aydin Muge , Hatirnaz Ozden , Erensoy Nevin , Ozbek Ugur 
Published: January 2005

AbstractDrugs and carcinogens are substrates of a group of metabolic enzymes including cytochrome p450 enzymes and gluthatione S‐transferases. Many of the genes encoding these enzymes exhibit functional polymorphisms that contribute individual cancer susceptibility and drug response. Molecular studies based on these polymorphic enzymes also explain the aetiology of cancer and therapeutic management in clinics. We analysed the cytochrome p4501A1 (CYP1A1) and 2D6 (CYP2D6) variant genotype and allele frequencies by PCR‐RFLP in Turkish individuals (n = 140). The frequency of the CYP1A1*2A mutant allele was found to be 15.4%, and the CYP2D6*3 and *4 mutant allele (poor metabolizer) frequencies were 2.5% and 13.9%, respectively. This study presents the first results of CYP1A1 and CYP2D6 mutant allele distributions in the Turkish population and these data provide an understanding of epidemiological studies that correlate therapeutic approaches and aetiology of several types of malignancy in Turkish patients. Copyright © 2005 John Wiley & Sons, Ltd.
Induction of DNA‐Double‐Strand Breaks by Auger Electrons from 99mTc Complexes with DNA‐Binding Ligands
Authors: Häfliger Pascal , Agorastos Nikos , Spingler Bernhard , Georgiev Oleg , Viola Giampietro , Alberto Roger 
Published: January 2005

AbstractThe potential of certain Auger electron emitting nuclides for systemic radiotherapeutic applications has recently gained much attention. In particular, the ability of several nuclides, including 111In, 125I, and 123I, to induce DNA double‐strand breaks (dsb), a good indicator of cytotoxicity, has been extensively studied. However, this ability has never previously been shown experimentally for 99mTc, which, besides the well‐known γ radiation that is used for diagnostic applications, also emits an average of 1.1 conversion electrons and 4 Auger or Coster–Kronig electrons per decay. Owing to the short range of Auger electrons, the radionuclide needs to be located very close to the DNA for dsb to occur. We synthesized two cationic 99mTcI–tricarbonyl complexes with pendant DNA binders, pyrene and anthraquinone. The X‐ray crystal structures of the two complexes could be elucidated. Linear dichroism and UV/Vis spectroscopy revealed that the complex with pyrene intercalates DNA with a stability constant, K, of 1.1×106 M−1, while the analogous complex with anthraquinone interacts with DNA in a groove‐binding mode and has an affinity value of K=8.9×104 M−1. We showed with ϕX174 double‐stranded DNA that the corresponding 99mTc complexes induce a significant amount of dsb, whereas non‐DNA‐binding [TcO4]− and nonradioactive Re compounds did not. These results indicate that the Auger electron emitter 99mTc can induce dsb in DNA when decaying in its direct vicinity and this implies potential for systemic radiotherapy with 99mTc complexes.
A New Type of Metalloprotein: The Mo Storage Protein from Azotobacter vinelandii Contains a Polynuclear Molybdenum–Oxide Cluster
Authors: Fenske Dirk , Gnida Manuel , Schneider Klaus , Meyer‐Klaucke Wolfram , Schemberg Jörg , Henschel Volker , Meyer Anne‐Katrin , Knöchel Arndt , Müller Achim 
Published: January 2005

AbstractAzotobacter vinelandii is a diazotrophic bacterium characterized by the outstanding capability of storing Mo in a special storage protein, which guarantees Mo‐dependent nitrogen fixation even under growth conditions of extreme Mo starvation. The Mo storage protein is constitutively synthesized with respect to the nitrogen source and is regulated by molybdenum at an extremely low concentration level (0–50 nM). This protein was isolated as an α4β4 octamer with a total molecular mass of about 240 kg mol−1 and its shape was determined by small‐angle X‐ray scattering. The genes of the α and β subunits were unequivocally identified; the amino acid sequences thereby determined reveal that the Mo storage protein is not related to any other known molybdoprotein. Each protein molecule can store at least 90 Mo atoms. Extended X‐ray absorption fine‐structure spectroscopy identified a metal–oxygen cluster bound to the Mo storage protein. The binding of Mo (biosynthesis and incorporation of the cluster) is dependent on adenosine triphosphate (ATP); Mo release is ATP‐independent but pH‐regulated, occurring only above pH 7.1. This Mo storage protein is the only known noniron metal storage system in the biosphere containing a metal–oxygen cluster.
The Functional Role of Selenocysteine (Sec) in the Catalysis Mechanism of Large Thioredoxin Reductases: Proposition of a Swapping Catalytic Triad Including a Sec‐His‐Glu State
Authors: Brandt Wolfgang , Wessjohann Ludger A. 
Published: January 2005

AbstractThioredoxin reductases catalyse the reduction of thioredoxin disulfide and some other oxidised cell constituents. They are homodimeric proteins containing one FAD and accepting one NADPH per subunit as essential cofactors. Some of these reductases contain a selenocysteine at the C terminus. Based on the X‐ray structure of rat thioredoxin reductase, homology models of human thioredoxin reductase were created and subsequently docked to thioredoxin to model the active complex. The formation of a new type of a catalytic triad between selenocysteine, histidine and a glutamate could be detected in the protein structure. By means of DFT (B3LYP, lacv3p**) calculations, we could show that the formation of such a triad is essential to support the proton transfer from selenol to a histidine to stabilise a selenolate anion, which is able to interact with the disulfide of thioredoxin and catalyses the reductive disulfide opening. Whereas a simple proton transfer from selenocysteine to histidine is thermodynamically disfavoured by some 18 kcal mol−1, it becomes favoured when the carboxylic acid group of a glutamate stabilises the formed imidazole cation. An identical process with a cysteine instead of selenocysteine will require 4 kcal mol−1 more energy, which corresponds to a calculated equilibrium shift of ∼1000:1 or a 103 rate acceleration: a value close to the experimental one of about 102 times. These results give new insights into the catalytic mechanism of thioredoxin reductase and, for the first time, explain the advantage of the incorporation of a selenocysteine instead of a cysteine residue in a protein.
Kinetics Study of Bungarus fasciatus Venom Acetylcholinesterase Immobilised on a Langmuir–Blodgett Proteo‐Glycolipidic Bilayer
Authors: Godoy Stéphanie , Violot Sébastien , Boullanger Paul , Bouchu Marie‐Noëlle , Leca‐Bouvier Béatrice D. , Blum Loïc J. , Girard‐Egrot Agnès P. 
Published: January 2005

AbstractThis study deals with the kinetics properties of an enzyme immobilised in a defined orientation in a biomimetic environment. For this purpose, acetylcholinesterase (AChE) was captured at the surface of a nanostructured proteo‐glycolipidic Langmuir–Blodgett film through specific recognition by a noninhibitor monoclonal antibody (IgG) inserted in a neoglycolipid bilayer. Modelling of this molecular assembly provided a plausible interpretation of the functional orientation of the enzyme. The AChE activity being stable for several weeks, the enzyme kinetics were investigated, and fitted perfectly with heterogeneous biocatalytic behaviour representative of cellular enzymatic catalysis. The AChE–IgG–glycolipid nanostructure was directly interfaced with an efficient optical device. Such an association, leading to an intimate contact between the nanostructure and the biochemical signal transducer, gives direct access to the intrinsic AChE behaviour. This study thus demonstrates the potential for direct investigation of the kinetic behaviour of an immobilised enzyme on a lipid bilayer through an efficient transduction system.
Primary chemotherapy with cyclophosphamide, methotrexate, and 5‐fluorouracil in operable breast carcinoma
Authors: Falo Catalina , Moreno Abelardo , Benito Enrique , Lloveras Belen , Varela Mar , Serra Jose Ma , Prieto Luis , Azpeitia Diego , Escobedo Agustin 
Published: January 2005

AbstractBACKGROUNDPrimary chemotherapy (PC) is becoming an accepted practice to treat large tumors to avoid mastectomies and as a surrogate of outcome.METHODSA series of 305 patients with tumors > 3 cm with T2–3N0–1M0 classification were treated with a multimodal approach that consisted of 3 courses of primary cyclophosphamide, methotrexate, and 5‐fluorouracil (CMF) followed by appropriate local treatment and 3 more courses of CMF or 4 courses of doxorubicin. Response was assessed by mammography.RESULTSThe overall response rate was 48% (a 3% pathologic complete response rate). Conservative surgery was achieved in 79.64% of the patients with a low rate of local disease recurrences (5%). Toxicity was minimal. With a median follow‐up of 104 months, the 8‐year disease‐free survival (DFS) rate was 57.63% and the 8‐year overall survival (OS) was 67.65%. The DFS and OS rates for patients with a clinical response were significantly longer, i.e., 70% (P = 0.0048) and 90% (P = 0.0042), respectively.CONCLUSIONSPC with CMF was feasible. A high rate of breast‐conservative surgery was achieved. The current results stressed the value of PC to increase conservative surgery and as a predictor of outcome. Cancer 2005. © 2005 American Cancer Society.
More on the evolution of bed material waves in alluvial rivers
Authors: Cui Yantao , Parker Gary , Lisle Thomas E. , Pizzuto James E. , Dodd Annjanette M. 
Published: January 2005

AbstractSediment waves or pulses can form in rivers following variations in input from landslides, debris ﬂows, and other sources. The question as to how rivers cope with such sediment inputs is of considerable practical interest. Experimental, numerical and ﬁeld evidence assembled by the authors suggests that in mountain gravel‐bed streams, such pulses show relatively little translation, instead mostly dispersing in place. This research has recently been the subject of discussion. In particular it has been suggested that (a) the equations of ﬂow and sediment mass balance used in the analyses, and in most other morphodynamic analyses, require correction; (b) the dominance of dispersion appears only because the hyperbolic nature of the governing equations has not been adequately considered; and (c) the sediment transport equation used in the analyses does not lead to generalizable results. Here we suggest that (a) the relations for mass balance do not require the indicated correction; (b) the hyperbolic nature of the governing equations does not preclude the result of dispersion dominating translation in mountain streams; and (c) the general behaviour of an appropriate hyperbolic model of sediment waves (pulses) includes the relative roles of dispersion and translation, and is not affected by the precise choice of a sediment transport relation (as long as the choice is reasonable for the case in question). Copyright © 2005 John Wiley & Sons, Ltd.
Implicit finite element discretizations based on the flux‐corrected transport algorithm
Authors: Möller Matthias , Kuzmin D. , Turek S. 
Published: January 2005

AbstractThe flux‐corrected transport (FCT) methodology is generalized to implicit finite element schemes and applied to the Euler equations of gas dynamics. For scalar equations, a local extremum diminishing scheme is constructed by adding artificial diffusion so as to eliminate negative off‐diagonal entries from the high‐order transport operator. To obtain a nonoscillatory low‐order method in the case of hyperbolic systems, the artificial viscosity tensor is designed so that all off‐diagonal blocks of the discrete Jacobians are rendered positive semi‐definite. Compensating antidiffusion is applied within a fixed‐point defect correction loop so as to recover the high accuracy of the Galerkin discretization in regions of smooth solutions. All conservative matrix manipulations are performed edge‐by‐edge which leads to an efficient algorithm for the matrix assembly. Copyright © 2005 John Wiley & Sons, Ltd.
Snow, frozen soils and permafrost hydrology in Canada, 1999–2002
Authors: Woo Ming‐Ko , Marsh Philip 
Published: January 2005

AbstractAn overview is provided of Canadian research on snow, frozen soils and permafrost hydrology for 1999–2002, the period between the 1999 IUGG meeting in Birmingham and the 2003 IUGG in Sapporo. Snow research during this period emphasized the blowing snow and sublimation processes, the role of trees in snow distribution, and melt and the effect of heat advection on snowmelt, from patch to regional scales. Regional‐scale studies, largely in connection with the Mackenzie GEWEX study, examined the snow conditions of the lower Mackenzie basin and developed a coupled land surface scheme–hydrological model that incorporates snow processes. In frost hydrology, the effects of organic soils on runoff generation and flow delivery were given much attention. Field investigations ranged from plot to hillslope scales, and the results indicate that organic layers of high porosity permit the production of quick flow, even when frozen. Highly fractured bedrock in the Canadian Shield has likewise the effect of permitting snowmelt infiltration at below‐freezing temperatures. Finally, changes in snow‐covered areas and in snow equivalent over periods from a decade to a century were examined. The responses of snow and ground ice to the warm year of 1998 were also studied as an indication of hydrological responses to climatic warming. Copyright © 2005 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Advances in Canadian forest hydrology, 1999–2003
Authors: Buttle J. M. , Creed I. F. , Moore R. D. 
Published: January 2005

AbstractUnderstanding key hydrological processes and properties is critical to sustaining the ecological, economic, social and cultural roles of Canada's varied forest types. This review examines recent progress in studying the hydrology of Canada's forest landscapes. Work in some areas, such as snow interception, accumulation and melt under forest cover, has led to modelling tools that can be readily applied for operational purposes. Our understanding in other areas, such as the link between runoff‐generating processes in different forest landscapes and hydrochemical fluxes to receiving waters, is much more tentative. The 1999–2003 period saw considerable research examining hydrological and biogeochemical responses to natural and anthropogenic disturbance of forest landscapes, spurred by major funding initiatives at the provincial and federal levels. This work has provided valuable insight; however, application of the findings beyond the experimental site is often restricted by such issues as a limited consideration of the background variability of hydrological systems, incomplete appreciation of hydrological aspects at the experiment planning stage, and experimental design problems that often bedevil studies of basin response to disturbance. Overcoming these constraints will require, among other things, continued support for long‐term hydroecological monitoring programmes, the embedding of process measurement and modelling studies within these programmes, and greater responsiveness to the vagaries of policy directions related to Canada's forest resources. Progress in these and related areas will contribute greatly to the development of hydrological indicators of sustainable forest management in Canada. Copyright © 2005 John Wiley & Sons, Ltd.
Controls on runoff from a partially harvested aspen‐forested headwater catchment, Boreal Plain, Canada
Authors: Devito K. J. , Creed I. F. , Fraser C. J. D. 
Published: January 2005

AbstractThe water balance and runoff regime of a 55 ha aspen‐forested headwater catchment located on the Boreal Plain, Alberta, Canada (55·1°N, 113·8°W) were determined for 5 years following a partial timber harvest. Variability in precipitation provided the opportunity to contrast catchment water balances in relatively dry (<350 mm year−1), wet (>500 mm year−1), and average precipitation years. In most years, the catchment water balance was dominated by soil water storage, evapotranspiration losses, and vertical recharge. In 1997, despite near‐average annual precipitation (486 mm), there was significant runoff (250 mm year−1) with a runoff coefficient of 52%. A wet summer and autumn in the preceding year (1996) and large snow accumulation in the spring (1997) reduced the soil water storage potential, and large runoff occurred in response to a substantial July rainfall event. Maps of the surface saturated areas indicated that runoff was generated from the uplands, ephemeral draws, and valley‐bottom wetlands. Following 1997, evapotranspiration exceeded precipitation and large soil water storage potentials developed, resulting in a reduction in surface runoff to 11 mm in 1998, and <2 mm in 1999–2001. During this time, the uplands were hydrologically disconnected from ephemeral draws and valley‐bottom wetlands. Interannual variability was influenced by the degree of saturation and connectivity of ephemeral draws and valley wetlands. Variability in runoff from tributaries within the catchment was influenced by the soil water storage capacity as defined by the depth to the confining layer. An analysis of the regional water balance over the past 30 years indicated that the potential to exceed upland soil water storage capacity, to connect uplands to low‐lying areas, and to generate significant runoff may only occur about once every 20 years. The spatial and temporal variability of soil water storage capacity in relation to evaporation and precipitation deficits complicates interpretation of forest harvesting studies, and low runoff responses may mask the impacts of harvesting of aspen headwater areas on surface runoff in subhumid climates of the Boreal Plain. Copyright © 2005 John Wiley & Sons, Ltd.
Hydrological processes in major types of Chinese forest
Authors: Wei X. , Liu S. , Zhou G. , Wang C. 
Published: January 2005

AbstractOverexploitation of forest resources in China has caused serious concerns over its negative impacts on water resources, biodiversity, soil erosion, wildlife habitat and community stability. One key concern is the impact of forestry practices on hydrological processes, particularly the effect of forest harvest on water quality and quantity. Since the mid 1980s, a series of scientific studies on forest hydrology have been initiated in major types of forest across the country, including Korean pine (Pinus koraiensis), Chinese fir (Cunninghamia lanceolata), oak (Quercus mongolica), larch (Larix gmelinii), faber fir (Abies fabri), Chinese pine (Pinus tabulaeformis), armand pine (Pinus arandi), birch (Betula platyphylla) and some tropical forests. These studies measured rainfall interception, streamflow, evapotranspiration and impacts of forest management (clearcutting and reforestation). This paper reviews key findings from these forest hydrological studies conducted over the past 20 years in China.Forest canopy interception rates varied from 15 to 30% of total rainfall, depending on forest canopy and rainfall characteristics. Stemflow is generally a small percentage (<5%) of total rainfall, but it accounts for 15% in the oak forest in northeast China. The high amounts of stemflow, as well as higher amounts of nutrients contained in stemflow, may allow oak trees to adapt to a dry and nutrient‐poor environment. Evapotranspiration was a significant component of the water budget in these Chinese forests studied, ranging from 80–90% of total rainfall in the northern temperate forests to 40–50% in the southern tropical forests. Forests substantially reduced surface runoff and erosion. However, no consistent response on total streamflows was observed. The reason for the inconsistency may be due to complexities of streamflow processes and the utilization of different methodologies applied at the various spatial scales. Copyright © 2005 John Wiley & Sons, Ltd.
Stereodynamics of bond rotation in tertiary 1‐naphthoic acid amides: A computational study
Authors: Campomanes Pablo , Menéndez M. Isabel , López Ramón , Sordo Tomás L. 
Published: January 2005

AbstractComputations sho that independent NCO rotation is not possible inN,N‐diethyl‐1‐naphthamide, and that the coalescence signal corresponding to methyl equivalence observed in the VT NMR spectrum of this system is caused by a complex process whose rate‐determining step implies concerted NCO, ArCO, and ethyl rotations. The calculated Gibbs energy barriers for these processes in solution are in good agreement with the experimental values. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 365–373, 2005
Interaction of sodium and potassium ions with sandwiched cytosine‐, guanine‐, thymine‐, and uracil‐base tetrads
Authors: Meyer Michael , Hocquet Alexandre , Sühnel Jürgen 
Published: January 2005

AbstractNucleic acid tetraplexes and lipophilic self‐assembling G‐quadruplexes contain stacked base tetrads with intercalated metal ions as basic building blocks. Thus far, quantum‐chemical studies have been used to explore the geometric and energetic properties of base tetrads with and without metal ions. Recently, for the first time, work on a sandwiched G‐tetrad complex has been studied. We report here results of a systematic B3LYP density functional study on sandwiched G‐, C‐, U‐, and T‐tetrads with Na+ and K+ at different symmetries that substantially extend the recent work. The results include detailed information on total energies as well as on metal ion tetrad and base–base interaction energies. The geometrical parameters of the sandwiched metal ion complexes are compared to both experimental structures and to calculated geometries of complexes of single tetrads with metal ions. A microsolvation model explains the ion selectivity preference of K+ over Na+ in a qualitative sense. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 352–364, 2005