bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of a thrombomodulin binding site on protein C and its comparison to an activated protein C binding site for factor Va
Authors: Gale Andrew J. , Griffin John H.
Published: January 2004

Activation of the anticoagulant human plasma serine protease zymogen, protein C, by a complex of thrombin and the membrane protein, thrombomodulin, generates activated protein C, a physiologic anti‐thrombotic, anti‐inflammatory and anti‐apoptotic agent. Alanine‐scanning site‐directed mutagenesis of residues in five surface loops of an extensive basic surface on protein C was used to identify residues that play essential roles in its activation by the thrombin‐thrombomodulin complex. Twenty‐three residues in the protein C protease domain were mutated to alanine, singly, in pairs or in triple mutation combinations, and mutants were characterized for their effectiveness as substrates of the thrombin‐thrombomodulin complex. Three protein C residues, K192, R229, and R230, in two loops, were identified that provided major contributions to interactions with thrombin‐thrombomodulin, while six residues, S190, K191, K217, K218, W231, and R312, in four loops, appeared to provide minor contributions. These protein C residues delineated a positively charged area on the molecule's surface that largely overlapped the previously characterized factor Va binding site on activated protein C. Thus, the extensive basic surface of protein C and activated protein C provides distinctly different, though significantly overlapping, binding sites for recognition by thrombin‐thrombomodulin and factor Va. Proteins 2004;54:000–000. © 2004 Wiley‐Liss, Inc.
Metal‐Induced reversible structural interconversion of human mitochondrial NAD(P)+‐Dependent malic enzyme
Authors: Kuo Chu‐Wei , Hung Hui‐Chih , Tong Liang , Chang Gu‐Gang
Published: January 2004

Human mitochondrial NAD(P)+‐dependent malic enzyme was strongly inhibited by Lu3+. The X‐ray crystal structures indicated a structural change between the metal‐free and Lu3+‐containing enzymes (Yang Z, Batra R, Floyd DL, Hung HC, Chang GG, Tong L. Biochem Biophys Res Commun 2000;274:440–444). We characterized the reversible slow‐binding mechanism and the structural interconversion between Mn2+‐ and Lu3+‐containing human mitochondrial malic enzymes. When Lu3+ was added, the activity of the human enzyme showed a downward curve over time, similar to that of the pigeon enzyme. The rate of the transformation (kobs) from the initial rate to the steady‐state rate increased hyperbolically with the concentration of Lu3+, suggesting the involvement of an isomerization step. Lu3+ had a much higher affinity for the isomerized form (K*i,Lu (app) = 4.8 μM) than that of the native form (Ki,Lu (app) = 148 μM). When an excess of Mn2+ was added to the Lu3+‐inhibited enzyme, assays of the kinetic activity showed an upward trend, indicating reactivation. This result also indicated that the reactivation was a slow process. Fluorescence quenching experiments confirmed that the Lu3+‐induced isomerization was completely reversible. The dynamic quenching constants for the metal‐free, Mn2+‐containing, and Lu3+‐containing enzyme were 3.08, 3.07, and 3.8 M−1, respectively. When the Lu3+‐containing enzyme was treated with excess Mn2+, the dynamic quenching constant returned to the original value (3.09 M−1). These results indicated that binding of Mn2+ did not induce any conformational change in the enzyme. The open form transformed to the closed form only after substrate binding. Lu3+, on the other hand, transformed the open form into a catalytically inactive form. Excess Mn2+ could replace Lu3+ in the metal binding site and convert the inactive form back into the open form. This reversible process was slow in both directions because of the same but opposite structural change involved. Proteins 2004;54:000–000. © 2004 Wiley‐Liss, Inc.
Monitoring glyphosate residues in transgenic glyphosate‐resistant soybean
Authors: Arregui María C , Lenardón Argelia , Sanchez Daniel , Maitre María I , Scotta Roberto , Enrique Susana
Published: January 2004

The availability of Roundup Ready (RR) varieties of soybean has increased the use of glyphosate for weed control in Argentina. Glyphosate [(N‐phosphonomethyl)glycine] is employed for the eradication of previous crop vegetation and for weed control during the soybean growing cycle. Its action is effective, and low environmental impact has been reported so far. No residues have been observed in soil or water, either of glyphosate or its metabolite, AMPA (aminomethylphosphonic acid). The objective of this work was to monitor glyphosate and AMPA residues in soybean plants and grains in field crops in Santa Fe Province, Argentina. Five sites were monitored in 1997, 1998 and 1999. Individual soybean plants were sampled from emergence to harvest, dried and ground. Analysis consisted in residue extraction with organic solvents and buffers, agitation, centrifugation, clean‐up and HPLC with UV detection. In soybean leaves and stems, glyphosate residues ranged from 1.9 to 4.4 mg kg−1 and from 0.1 to 1.8 mg kg−1 in grains. Higher concentrations were detected when glyphosate was sprayed several times during the crop cycle, and when treatments approached the flowering stage. AMPA residues were also detected in leaves and in grains, indicating metabolism of the herbicide. Copyright © 2003 Society of Chemical Industry
Synthesis and antifungal activity of five classes of diamines
Authors: Ross William F , Walters Dale R , Robins David J
Published: January 2004

Examples of five classes of diamines were synthesized and tested for antifungal activity. Two classes, the bis(cyclohexylmethyl)diamines and the bis(benzyl)diamines, were most effective in reducing mycelial growth of the oat leaf stripe pathogen Pyrenophora avenae Ito & Kuribay when used at a concentration of 250 µM. The bis(benzyl)diamine BBD5 and the hydroxypyridylethylamine HPE2 both reduced powdery mildew infection of barley seedlings by greater than 70% when applied as a post‐inoculation spray at 250 µM. Several of the compounds examined, and especially BBD5 and HPE2, reduced the formation of spermidine but greatly increased spermine levels. These changes in P avenae treated with BBD5 and HPE2 were also accompanied by greatly elevated activity of polyamine oxidase. It is suggested that the antifungal activity of these compounds may be related to the accumulation of spermine and specifically to its toxicity. Copyright © 2004 Society of Chemical Industry
Potassium phosphate induces systemic protection in barley to powdery mildew infection
Authors: Mitchell Anne F , Walters Dale R
Published: January 2004

In laboratory tests, treatment of the first leaves of barley (Hordeum vulgare L cv Golden Promise) with potassium phosphate led to significant reduction in infection of the second leaves with the powdery mildew fungus Blumeria graminis f sp hordei Marchal, with a 25 mM treatment giving 89% reduction in infection. Although the optimal interval between phosphate treatment of the first leaves and mildew inoculation of the second leaves was 2 days, significant protection was still obtained if the interval was increased to 12 days. Protection against powdery mildew infection was not as effective when the potassium phosphate was applied as a seed treatment or root drench. Phosphate treatment of the first leaves led to significant increases in activities of phenylalanine ammonia lyase (PAL), peroxidase and lipoxygenase in second leaves. Enzyme activities, especially PAL and peroxidase, were increased further when second leaves of phosphate‐treated plants were inoculated with powdery mildew. Phosphate treatment of the first leaves did not adversely affect plant growth and, in a field trial, 25 mM potassium phosphate provided 70% control of mildew and gave a small increase in grain yield. Copyright © 2004 Society of Chemical Industry
Occurrence of barley yellow dwarf virus in autumn‐sown cereal crops in the United Kingdom in relation to field characteristics
Authors: Foster Garth N , Blake Shona , Tones Steve J , Barker Ian , Harrington Richard
Published: January 2004

The incidence of barley yellow dwarf virus and of its aphid vectors was surveyed in untreated parts of autumn‐sown cereal crops, mainly wheat and barley, in the United Kingdom in 1995–8. The incidence of virus in the spring was related to the incidence of aphids in the preceding autumn. Both virus and aphid incidences could also be related to a range of crop and field characteristics, in particular sowing date, regions as defined by their geographical position, topography and climate, the proximity of the field to the sea, the extent of arable land in the vicinity of the field, and the aspect and size of the field. Proximity of cropped fields to setaside areas had no significant effect on either aphid or virus incidence. Copyright © 2004 Society of Chemical Industry
Molluscicidal effects of neem (Azadirachta indica) extracts on edible tropical land snails
Authors: Ebenso Ime E
Published: January 2004

The effects of 350, 500 and 700 mg kg−1 of crude extracts of neem, Azadirachta indica A Juss, on edible tropical land snails Archachatina marginata and Limicolaria aurora (Jay) were determined and compared with control using pawpaw, Carica papaya L as bait. Responses were measured through normal feeding, cessation of food intake, cessation of crawling, mucus secretion, lack of response to mechanical stimuli (mortality) and decomposition. Results showed no effects on the controls or snails exposed to neem seed oil extract. Crude extracts of bark, root and leaf of neem at 500 and 700 mg kg−1 produced mortality after exposure for 48 h for L aurora and 72 h for A marginata. Copyright © 2004 Society of Chemical Industry
Benzoylphenylurea residues in peppers and zucchinis grown in greenhouses: determination of decline times and pre‐harvest intervals by modelling
Authors: López‐López Trinidad , Martínez‐Vidal José L , Gil‐García María D , Martínez‐Galera María , Rodríguez‐Lallena José A
Published: January 2004

Residue levels and degradation rates of five benzoylphenylurea insecticides were studied in zucchinis and peppers grown in experimental greenhouses in Almería (Spain). Benzoylphenylurea residues were analyzed by HPLC using on‐line post‐elution photoirradiation with fluorescence detection. Mathematically defined decline curves were established by determining optimal relationships between benzoylphenylurea residues and time, using different models. The models that best fitted the experimental data were those of first‐order for diflubenzuron, triflumuron, hexaflumuron and flufenoxuron in zucchini and RF first‐order models for the five insecticides in peppers and for lufenuron in zucchini. Half‐life times for the residues on the two vegetables were estimated from the optimal models. In order to guarantee safe consumption of the two vegetables, we have estimated suitable pre‐harvest intervals complying with the maximum residue levels established by the Spanish Government. In all cases, such pre‐harvest intervals were shorter than those specified by the manufacturers of commercial formulates. Experimental data for the five insecticides in peppers and for lufenuron in zucchini were also fitted to a first‐order model. Even though this function was legitimized statistically, estimations of decline times (T/2) and pre‐harvest intervals were quite different from those provided by the optimal model. Copyright © 2004 Society of Chemical Industry
Responses of Corcyra cephalonica (Stainton) to pirimiphos‐methyl, spinosad, and combinations of pirimiphos‐methyl and synergized pyrethrins
Authors: Huang Fangneng , Subramanyam Bhadriraju
Published: January 2004

Field control failures with pirimiphos‐methyl against the rice moth, Corcyra cephalonica (Stainton), in Weslaco, Texas, USA, led us to investigate the susceptibility of this particular strain to pirimiphos‐methyl, spinosad, pyrethrins synergized with piperonyl butoxide, and pirimiphos‐methyl combined with synergized pyrethrins. In laboratory bioassays, 50 eggs of C cephalonica were exposed to untreated and insecticide‐treated corn and sunflower seeds to determine larval survival after 21 days, egg‐to‐adult emergence after 49 days, and larval damage to seeds at both exposure periods. Pirimiphos‐methyl at both 4 and 8 mg kg−1 did not prevent larval survival or egg‐to‐adult emergence of C cephalonica on either corn or sunflower seeds, and seed damage was evident at both rates. The C cephalonica strain was highly susceptible to spinosad at 0.5 and 1 mg kg−1. At both spinosad rates, reduction in larval survival, egg‐to‐adult emergence, and seed damage relative to the control treatment was ≥93% on both corn and sunflower seeds. Pirimiphos‐methyl and spinosad were generally more effective against C cephalonica on corn than sunflower seeds. The C cephalonica strain was completely controlled on corn treated with 1.5 mg kg−1 of pyrethrins synergized with 15 mg kg−1 of piperonyl butoxide. Many larvae survived and became adults on corn treated with synergized pyrethrins at ≤0.75 mg kg−1. Corn treated with pirimiphos‐methyl at 4, 6 or 8 mg kg−1 in combination with 0.38 to 1.5 mg kg−1 of synergized pyrethrins reduced larval survival by ≥95%, egg‐to‐adult emergence by ≥97%, and seed damage by ≥94%. Our results suggest that the C cephalonica strain can be controlled on corn by combining pirimiphos‐methyl with synergized pyrethrins or with synergized pyrethrins at the labeled rate. Although spinosad is not currently labeled for use on stored corn and sunflower seeds, it appears to be effective against C cephalonica on both commodities at very low rates. Copyright © 2004 Society of Chemical Industry
The potential role of arbuscular mycorrhizal (AM) fungi in the bioprotection of plants against soil‐borne pathogens in organic and/or other sustainable farming systems
Authors: Harrier Lucy A , Watson Christine A
Published: January 2004

Sustainable farming systems strive to minimise the use of synthetic pesticides and to optimise the use of alternative management strategies to control soil‐borne pathogens. Arbuscular mycorrhizal (AM) fungi are ubiquitous in nature and constitute an integral component of terrestrial ecosystems, forming symbiotic associations with plant root systems of over 80% of all terrestrial plant species, including many agronomically important species. AM fungi are particularly important in organic and/or sustainable farming systems that rely on biological processes rather than agrochemicals to control plant diseases. Of particular importance is the bioprotection conferred to plants against many soil‐borne pathogens such as species ofAphanomyces, Cylindrocladium, Fusarium, Macrophomina, Phytophthora, Pythium, Rhizoctonia, Sclerotinium, VerticilliumandThielaviopsisand various nematodes by AM fungal colonisation of the plant root. However, the exact mechanisms by which AM fungal colonisation confers the protective effect are not completely understood, but a greater understanding of these beneficial interactions is necessary for the exploitation of AM fungi within organic and/or sustainable farming systems. In this review, we aim to discuss the potential mechanisms by which AM fungi may contribute to bioprotection against plant soil‐borne pathogens. Bioprotection within AM fungal‐colonised plants is the outcome of complex interactions between plants, pathogens and AM fungi. The use of molecular tools in the study of these multifaceted interactions may aid the optimisation of the bioprotective responses and their utility within sustainable farming systems. Copyright © 2004 Society of Chemical Industry
Approaches to Measure Chemical Similarity – a Review
Authors: Nikolova Nina , Jaworska Joanna
Published: January 2004

Although the concept of similarity is a convenient for humans, a formal definition of similarity between chemical compounds is needed to enable automatic decision‐making. The objective of similarity measures in toxicology and drug design is to allow assessment of chemical activities. The ideal similarity measure should be relevant to the activity of interest. The relevance could be established by exploiting the knowledge about fundamental chemical and biological processes responsible for the activity. Unfortunately, this knowledge is rarely available and therefore different approximations have been developed based on similarity between structures or descriptor values. Various methods are reviewed, ranging from two‐dimensional, three‐dimensional and field approaches to recent methods based on “Atoms in Molecules” theory. All these methods attempt to describe chemical compounds by a set of numerical values and define some means for comparison between them. The review provides analysis of potential pitfalls of this methodology – loss of information in the representations of molecular structures – the relevance of a particular representation and chosen similarity measure to the activity. A brief review of known methods for descriptor selection is also provided. The popular “neighborhood behavior” principle is criticized, since proximity with respect to descriptors does not necessarily mean proximity with respect to activity. Structural similarity should also be used with care, as it does not always imply similar activity, as shown by examples. We remind that similarity measures and classification techniques based on distances rely on certain data distribution assumptions. If these assumptions are not satisfied for a given dataset, the results could be misleading. A discussion on similarity in descriptor space in the context of applicability domain assessment of QSAR models is also provided. Finally, it is shown that descriptor based similarity analysis is prone to errors if the relationship between the activity and the descriptors has not been previously established. A justification for the usage of a particular similarity measure should be provided for every specific activity by expert knowledge or derived by data modeling techniques.
QSAR analysis of the time dependent hypotensive activity of 1‐[3‐(4‐substituted phenylthio)propyl]‐4‐(3,4‐substituted phenyl)piperazines using Artificial Neural Networks
Authors: Saxena Anil K. , Schaper Klaus‐Jürgen
Published: January 2004

The quantitative analysis and physicochemical description of time‐ and dose‐dependent in vivo drug effects is problematic as observed effects depend on both pharmacodynamics and pharmacokinetics. These factors depend in a different manner on the physicochemical properties of investigated drugs. Obviously in vivo effects of drug series are governed by highly non‐linear and extremely complicated relationships. The exact form of these relations usually can be given only for some restricted experimental conditions and generally may be assumed to be unknown. As the function relating in vivo hypotensive effects of the title compounds observed in cats, to dose, time and physicochemical properties could not be modelled explicitly, an attempt has been made to train an Artificial Neural Network (ANN) to find the unknown non‐linear relationship between input variables and observed % effect values (raw data, ±20–25% error). Although each drug was applied at only two different doses and “% effect” was observed at few time points, the weights characterising the ANN model enabled the calculation/prediction of (i) complete time‐activity profiles (reflecting mainly pharmacokinetics); (ii) physicochemical property dependent activities. Thus, a maximum of information was extracted from raw in vivo data by this approach which may be useful in saving animal experiments in drug development. However, complete dose‐response curves could not be obtained due to insufficient data in terms of applied doses.
Mass spectrometry for the detection of differentially expressed proteins: a comparison of surface‐enhanced laser desorption/ionization and capillary electrophoresis/mass spectrometry
Authors: Neuhoff Nils v. , Kaiser Thorsten , Wittke Stefan , Krebs Ronald , Pitt Andrew , Burchard Aurea , Sundmacher Astrid , Schlegelberger Brigitte , Kolch Walter , Mischak Harald
Published: January 2004

The discovery of biomarkers is currently attracting much interest as it harbors great potential for the diagnosis and monitoring of human diseases. Here we have used two advanced mass spectroscopy based technologies, surface enhanced laser desorption ionization (SELDI‐MS) and capillary electrophoresis/mass spectrometry (CE/MS), to obtain proteomic patterns of urine samples from patients suffering from membranous glomerulonephritis (MGN) and healthy volunteers. The results indicate that CE/MS analysis is able to display a rich and complex pattern of polypeptides with high resolution and high mass accuracy. In order to analyze these patterns, the MosaiqueVisu software was developed for peak identification, deconvolution and the display of refined maps in a three‐dimensional format. The polypeptide profiles obtained with SELDI‐MS from the same samples are much sparser and show lower resolution and mass accuracy. The SELDI‐MS profiles are further heavily dependent on analyte concentration. SELDI‐MS analysis identified three differentially expressed polypeptides, which are potential biomarkers that can distinguish healthy donors from patients with MGN. In contrast, approximately 200 potential biomarkers could be identified by CE/MS. Thus, while SELDI‐MS is easy to use and requires very little sample, CE/MS generates much richer data sets that enable an in‐depth analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Improvements and new capabilities for the multiple Knudsen cell device used in high‐temperature mass spectrometry
Authors: Heyrman M. , Chatillon C. , Collas H. , Chemin J.‐L.
Published: January 2004

The thermodynamic properties of condensed phases, i.e. the activities of components, can be determined from partial pressures measured by the Knudsen cell mass spectrometric method. Improvements in accuracy and yield of this method are obtained with the use of twin cells, an idea proposed in the 1960s. The multiple cell method was perfected in 1977 in our laboratory. Changes to molecular beam sampling and furnace assemblies were required to make the multiple Knudsen cell technique work properly. This paper summarizes these prerequisites, and presents a new device and the associated method of measurements, as well as the necessary tests performed with a silver sample in each cell. Copyright © 2003 John Wiley & Sons, Ltd.
Sensitive sulphur‐specific detection of omeprazole metabolites in rat urine by high‐performance liquid chromatography/inductively coupled plasma mass spectrometry
Authors: Jensen Berit Packert , Smith Christopher , Wilson Ian D. , Weidolf Lars
Published: January 2004

The use of high‐performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) with sulphur‐specific detection was investigated as a method for obtaining metabolite profiles for the drug omeprazole administered as a 1:1 mixture of 32S‐ and 34S‐labelled material. Analysis based on the monitoring of the chromatographic eluent at either m/z 32 or 34 was not successful due to insufficient sensitivity caused by interferences from polyatomic ions. However, reaction of sulphur with oxygen in the hexapole collision cell, combined with monitoring at m/z 48 (for 32S) or m/z 50 (for 34S), provided a facile method for metabolite profiling. Detection of m/z 48 was superior in sensitivity to detection of m/z 50. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of specific volatile organic compounds synthesised during Tuber borchii fruit body development by solid‐phase microextraction and gas chromatography/mass spectrometry
Authors: Zeppa Sabrina , Gioacchini Anna Maria , Guidi Chiara , Guescini Michele , Pierleoni Raffaella , Zambonelli Alessandra , Stocchi Vilberto
Published: January 2004

Fruit body development is a particular phase of the Tuber life cycle, characterised by the aggregation of different types of hyphae, i.e., vegetative hyphal cells and highly specialised reproductive hyphae (asci). In order to identify the volatile organic compounds (VOCs) produced in different stages of the Tuber borchii ripening fruit body, solid‐phase microextraction with gas chromatography and mass spectrometry was used. The volatile organic compounds were extracted using a DVB/CAR/PDMS 50/30 μm fiber placed for 10 min at room temperature in the truffle headspace. The results obtained reveal 49 compounds each of which was present only in a particular stage of maturation. 1‐octen‐3‐ol, aromadendrene, α‐farnesene and other terpenoid compounds were of particular interest, and their possible biological roles are discussed. The production of aromadendrene in the completely unripe fruit body suggests the existence of communication events in the early stage of ascomata formation between the fungus and the host plant. α‐Farnesene could represent a chemotactic attractant to saprophytic organisms in order to disperse the fungal spores in the environment. The identification of the VOCs produced by truffles during their maturation could give information about the processes underlying this phase of Tuber life cycle. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative analysis of triacylglycerol regioisomers in fats and oils using reversed‐phase high‐performance liquid chromatography and atmospheric pressure chemical ionization mass spectrometry
Authors: Fauconnot Laëtitia , Hau Jörg , Aeschlimann Jean‐Marc , Fay Laurent‐Bernard , Dionisi Fabiola
Published: January 2004

Positional distribution of fatty acyl chains of triacylglycerols (TGs) in vegetable oils and fats (palm oil, cocoa butter) and animal fats (beef, pork and chicken fats) was examined by reversed‐phase high‐performance liquid chromatography (RP‐HPLC) coupled to atmospheric pressure chemical ionization using a quadrupole mass spectrometer. Quantification of regioisomers was achieved for TGs containing two different fatty acyl chains (palmitic (P), stearic (S), oleic (O), and/or linoleic (L)). For seven pairs of ‘AAB/ABA’‐type TGs, namely PPS/PSP, PPO/POP, SSO/SOS, POO/OPO, SOO/OSO, PPL/PLP and LLS/LSL, calibration curves were established on the basis of the difference in relative abundances of the fragment ions produced by preferred losses of the fatty acid from the 1/3‐position compared to the 2‐position. In practice the positional isomers AAB and ABA yield mass spectra showing a significant difference in relative abundance ratios of the ions AA+ to AB+. Statistical analysis of the validation data obtained from analysis of TG standards and spiked oils showed that, under repeatability conditions, least‐squares regression can be used to establish calibration curves for all pairs. The regression models show linear behavior that allow the determination of the proportion of each regioisomer in an AAB/ABA pair, within a working range from 10 to 1000 μg/mL and a 95% confidence interval of ±3% for three replicates. Copyright © 2003 John Wiley & Sons, Ltd.
Combined effects of environmental factors and regulation on macrophyte vegetation along three rivers in western France
Authors: Bernez Ivan , Daniel Hervé , Haury Jacques , Ferreira Maria Teresa
Published: January 2004

The longitudinal changes of richness and composition of aquatic plants have been studied from headwaters to the fifth stream order in three rivers in western Brittany (France), the Orne, Sélune and Rance. All rivers are regulated by dams along their lower reaches. The total macrophyte richness differed between the rivers (61 to 150 taxa); it was lowest in the Sélune, which flows over a granite substratum throughout its basin. Absolute richness per site varied greatly between rivers, and between groups of sites either upstream or downstream of the dams, though consistently higher values were observed downstream. In contrast, the relative richness at the river basin scale was similar for the group of upstream (average 20 taxa) and downstream sites (average 28) of all rivers. At the site level, richness increased along all there rivers. Several sites below the dams had the highest richness per site, with more than 40 taxa. A shifting evolution of the macrophyte richness was revealed along the river axis, related to habitat heterogeneity and geological changes.

Of the 27 abiotic variables initially considered for canonical correspondence analysis, only five to six per river were retained by a forward selection procedure. The eigenvalues of the first two canonical axes explained 16.1 to 22.4% of the total biological variability and 53.9 to 67.7% of the species–environment relationships. The macrophyte distribution was mainly determined by the stream hierarchy, expressed by the distance to source and slope, and showed also the influence of regulation, i.e. the position of the site in relation to the dam. Other physical variables significantly contributed to plant distribution, namely particular habitat types, depth and geological substratum. Nutrient enrichment and organic pollution influences were the main secondary gradients for the Orne and Rance rivers. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of discharge reductions on salt wedge dynamics of the Ebro River
Authors: Sierra J. P. , Sánchez‐Arcilla A. , Figueras P. A. , González Del Río J. , Rassmussen E. K. , Mösso C.
Published: January 2004

The Ebro River is the largest freshwater course of Spain with a discharge (in the lower course) that has been reduced in the last few decades due to the construction of several dams and the corresponding increase of water demand and river regulation. The lowest stretch of this river (about 42 km) behaves most of the time as a highly stratified estuary with a salt wedge. The dynamics of this salt wedge are important from the ecologic and economic points of view and depend mainly on the river discharge, although other factors (like bathymetry and climatology) play a non‐negligible secondary role. The wedge dynamics would also be affected by the planned river diversion scheme towards other areas of Spain. This diversion plan would mean a reduction of about 15% of the annual discharge (in the Ebro lower course) and the corresponding impact should be carefully assessed.

With that aim a two‐layer hydrodynamic numerical model has been employed to evaluate the role of flow regulation in the Ebro salt wedge dynamics, with particular emphasis on the potential discharge reduction due to the planned water diversion. The model has been calibrated with data acquired during four field campaigns (one per season) carried out during 1999 and 2000. Different scenarios of discharge reduction have been studied. Model results suggest a significant increase of salt wedge extent and permanence associated with the planned diversion scheme. This would entail an increase of saltwater intrusion problems both for aquifers and crops. Copyright © 2003 John Wiley & Sons, Ltd.
S‐UMTS access network for broadcast and multicast service delivery: the SATIN approach
Authors: Narenthiran K. , Karaliopoulos M. , Evans B. G. , De‐Win W. , Dieudonne M. , Henrio P. , Mazzella M. , Angelou E. , Andrikopoulos I. , Philippopoulos P. I. , Axiotis D. I. , Dimitriou N. , Polydoros A. , Corazza G. E. , Vanelli‐Coralli A.
Published: January 2004

This paper proposes a complete satellite access network solution for multimedia broadcast multicast service (MBMS) delivery based on T‐UMTS standards. First, the benefits of MBMS delivery via satellite (SAT‐MBMS) for both S/T‐UMTS network operators are shown with market and business analysis. A new integrated S/T‐UMTS architecture for MBMS delivery is proposed featuring an intermediate module repeater (IMR) for coverage of urban areas. The architectural options of IMR and terminals are discussed considering the relevant cost and complexity. The IMR propagation channel conditions are investigated and a new propagation channel model is proposed. The potential of advanced coding schemes such as the layered coding technique to tackle the channel variations in broadcast/multicast environment is outlined. The functional and protocol architecture are defined along with the interface between the satellite access network and the UMTS core network. Required modifications on the terrestrial access scheme sub‐layers to support MBMS data are investigated and the relevant logical, transport and physical channels are selected. Based on the channel selection and the point‐to‐multipoint service nature, we define a generic radio resource management (RRM) strategy that takes into account both QoS and GoS requirements. The efficiency of the proposed solutions is evaluated in the presented simulation results, advocating the feasibility of the overall approach. Copyright © 2004 John Wiley & Sons, Ltd.
Estimating life expectancy and related probabilities in screen‐detected breast cancer patients with restricted follow‐up information
Authors: Straatman Huub , Verbeek André L. M. , Peer Petronella G. M. , Borm George
Published: January 2004

Issues such as life expectancy after diagnosis, the number of life years gained by early diagnosis through screening, the probability of dying from breast cancer or of dying from other causes during the lead time period or thereafter can be derived from information on complete survival after diagnosis. A method is presented to estimate complete survival and relevant outcomes after diagnosis of screen‐detected cancer when the follow‐up period is substantially shorter than the maximum follow‐up possible. Survival after diagnosis until death from breast cancer is modelled as the sum of the lead time (LT) and the post‐lead time (PLT), where both time periods follow exponential distributions and are assumed to be independent. The survival period after diagnosis until death from causes other than breast cancer (X) is assumed to follow a Gompertz distribution. The survival period after diagnosis until death from any cause (Z) is modelled as the minimum of LT+PLT and X. Maximum likelihood methods were then used to estimate all parameters of Z. This procedure for obtaining maximum likelihood estimates of Z does not need the cause of death (breast cancer or other), which is an advantage over most other methods. Especially in older patients, it may be difficult or even impossible to ascertain the true cause of death. The model was applied to data from the long‐term breast cancer screening programme in Nijmegen, the Netherlands. Complete survival was estimated on the basis of survival data on 528 screen‐detected breast cancer patients, diagnosed in 1975–1997 and with a mean follow‐up of 8.9 years. Estimated life expectancy ranged between 22.3 and 9.0 years for patients diagnosed at the age of 50 and 79 years, respectively, that is, 6.1 and 0.7 life years gained by screening. Through early diagnosis and treatment, screen‐detected patients diagnosed at the age of 50 years may have reduced their lifetime risk of dying from breast cancer from 79 per cent to 56 per cent; at the age of 79 the reduction of risk is reduced from 23 per cent to 13 per cent. Copyright © 2004 John Wiley & Sons, Ltd.
Bayesian methods for analysis of binary outcome data in cluster randomized trials on the absolute risk scale
Authors: Thompson Simon G. , Warn David E. , Turner Rebecca M.
Published: January 2004

A Bayesian hierarchical modelling approach to the analysis of cluster randomized trials has advantages in terms of allowing for full parameter uncertainty, flexible modelling of covariates and variance structure, and use of prior information. Previously, such modelling of binary outcome data required use of a log‐odds ratio scale for the treatment effect estimate and an approximation linking the intracluster correlation (ICC) to the between‐cluster variance on a log‐odds scale. In this paper we develop this method to allow estimation on the absolute risk scale, which facilitates clinical interpretation of both the treatment effect and the between‐cluster variance. We describe a range of models and apply them to data from a trial of different interventions to promote secondary prevention of coronary heart disease in primary care. We demonstrate how these models can be used to incorporate prior data about typical ICCs, to derive a posterior distribution for the number needed to treat, and to consider both cluster and individual level covariates. Using these methods, we can benefit from the advantages of Bayesian modelling of binary outcome data at the same time as providing results on a clinically interpretable scale. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling clustered survival data from multicentre clinical trials
Authors: Glidden David V. , Vittinghoff Eric
Published: January 2004

In randomized clinical trials, subjects are recruited at multiple study centres. Factors that vary across centres may exert a powerful independent influence on study outcomes. A common problem is how to incorporate these centre effects into the analysis of censored time‐to‐event data. We survey various methods and find substantial advantages in the gamma frailty model. This approach compares favourably with competing methods and appears minimally affected by violation of the assumption of a gamma‐distributed frailty. Recent computational advances make use of the gamma frailty model a practical and appealing tool for addressing centre effects in the analysis of multicentre trials. Copyright © 2004 John Wiley & Sons, Ltd.
Estimating linear regression models in the presence of a censored independent variable
Authors: Austin Peter C. , Hoch Jeffrey S.
Published: January 2004

The current study examined the impact of a censored independent variable, after adjusting for a second independent variable, when estimating regression coefficients using ‘naïve’ ordinary least squares (OLS), ‘partial’ OLS and full‐likelihood models. We used Monte Carlo simulations to determine the bias associated with all three regression methods. We demonstrated that substantial bias was introduced in the estimation of the regression coefficient associated with the variable subject to a ceiling effect when naïve OLS regression was used. Furthermore, minor bias was transmitted to the estimation of the regression coefficient associated with the second independent variable. High correlation between the two independent variables improved estimation of the censored variable's coefficient at the expense of estimation of the other coefficient. The use of ‘partial’ OLS and maximum‐likelihood estimation were shown to result in, at most, negligible bias in estimation. Furthermore, we demonstrated that the full‐likelihood method was robust under misspecification of the joint distribution of the independent random variables. Lastly, we provided an empirical example using National Population Health Survey (NPHS) data to demonstrate the practical implications of our main findings and the simple methods available to circumvent the bias identified in the Monte Carlo simulations. Our results suggest that researchers need to be aware of the bias associated with the use of naïve ordinary least‐squares estimation when estimating regression models in which at least one independent variable is subject to a ceiling effect. Copyright © 2004 John Wiley & Sons, Ltd.
Determinants of bribery in international business
Authors: Sanyal Rajib N. , Samanta Subarna K.
Published: January 2004

Levels of perceived bribe taking in 54 countries in two time periods were analyzed with respect to two
independent variables—their level of human development measuring education, wealth, and health (Human
Development Index) and the level of economic freedom measuring the extent to which a nation's economy
is open to market forces. The results indicate that lower levels of bribe taking are associated with high human
development and greater economic freedom. Developed countries that have shown improvements on the two variables
over a five‐year period also show a reduction in their perceived levels of bribe taking. © 2004 Wiley
Periodicals, Inc.
Investment and marketing strategies of Mexican companies in the United States: Preliminary evidence
Authors: Vasquez‐Parraga Arturo Z. , Felix Reto
Published: January 2004

Because of its geographic proximity to the United States and its favored position as a member of the North
American Free Trade Agreement (NAFTA), Mexico has become an emerging player in the global marketplace,
and this new position has motivated several Mexican companies to establish businesses in the United States.
Attempts have been made to explain why Mexican firms have become global players, explanations that focus on
several national and international factors. However, these factors omit important drivers of the process,
including entry and marketing strategies. This study aims to 1) give an account of how and why Mexican
companies enter the United States, and 2) identify some tendencies in the way U.S. subsidiaries of Mexican
companies develop and use marketing strategies to serve U.S. markets. © 2004 Wiley Periodicals, Inc.
Entrepreneurship and international business
Authors: Jadoon Zafar Iqbal , Khan Atif Rahim
Published: January 2004

Henry Wai‐chung Yeung. 2002. Entrepreneurship and the Internationalisation of Asian Firms: An
Institutional Perspective. Northampton, MA: Edward Elgar Publishing Limited. 311 pages. ISBN
1‐84064‐734‐5.

Victoria E. Bonnell & Thomas B. Gold (Eds.). 2002. The New Entrepreneurs of Europe and
Asia: Patterns of Business Development in Russia, Eastern Europe and China. Armonk, NY: M.E. Sharpe.
357 pages. ISBN 0‐7656‐0775‐1.
A DNA microarray for fission yeast: minimal changes in global gene expression after temperature shift
Authors: Xue Yongtao , Haas Stefan A. , Brino Laurent , Gusnanto Arief , Reimers Mark , Talibi Driss , Vingron Martin , Ekwall Karl , Wright Anthony P. H.
Published: January 2004

Completion of the fission yeast genome sequence has opened up possibilities for post‐genomic approaches. We have constructed a DNA microarray for genome‐wide gene expression analysis in fission yeast. The microarray contains DNA fragments, PCR‐amplified from a genomic DNA template, that represent > 99% of the 5000 or so annotated fission yeast genes, as well as a number of control sequences. The GenomePRIDE software used attempts to design similarly sized DNA fragments corresponding to gene regions within single exons, near the 3′‐end of genes that lack homology to other fission yeast genes. To validate the design and utility of the array, we studied expression changes after a 2 h temperature shift from 25 °C to 36 °C, conditions widely used when studying temperature‐sensitive mutants. Obligingly, the vast majority of genes do not change more than two‐fold, supporting the widely held view that temperature‐shift experiments specifically reveal phenotypes associated with temperature‐sensitive mutants. However, we did identify a small group of genes that showed a reproducible change in expression. Importantly, most of these corresponded to previously characterized heat‐shock genes, whose expression has been reported to change after more extreme temperature shifts than those used here. We conclude that the DNA microarray represents a useful resource for fission yeast researchers as well as the broader yeast community, since it will facilitate comparison with the distantly related budding yeast, Saccharomyces cerevisiae. To maximize the utility of this resource, the array and its component parts are fully described in On‐line Supplementary Information and are also available commercially. Copyright © 2003 John Wiley & Sons, Ltd.
KlSEC53 is an essential Kluyveromyces lactis gene and is homologous with the SEC53 gene of Saccharomyces cerevisiae
Authors: Staneva Dessislava , Uccelletti Daniela , Farina Francesca , Venkov Pencho , Palleschi Claudio
Published: January 2004

Phosphomannomutase (PMM) is a key enzyme, which catalyses one of the first steps in the glycosylation pathway, the conversion of D‐mannose‐6‐phosphate to D‐mannose‐1‐phosphate. The latter is the substrate for the synthesis of GDP‐mannose, which serves as the mannosyl donor for the glycosylation reactions in eukaryotic cells. In the yeast Saccharomyces cerevisiae PMM is encoded by the gene SEC53 (ScSEC53) and the deficiency of PMM activity leads to severe defects in both protein glycosylation and secretion. We report here on the isolation of the Kluyveromyces lactis SEC53 (KlSEC53) gene from a genomic library by virtue of its ability to complement a Saccharomyces cerevisiae sec53 mutation. The sequenced DNA fragment contained an open reading frame of 765 bp, coding for a predicted polypeptide, KlSec53p, of 254 amino acids. The KlSec53p displays a high degree of homology with phosphomannomutases from other yeast species, protozoans, plants and humans. Our results have demonstrated that KlSEC53 is the functional homologue of the ScSEC53 gene. Like ScSEC53, the KlSEC53 gene is essential for K. lactis cell viability. Phenotypic analysis of a K. lactis strain overexpressing the KlSEC53 gene revealed defects expected for impaired cell wall integrity. The sequence of the KlSEC53 has been deposited in the EMBL database under Accession No. AJ428418. Copyright © 2003 John Wiley & Sons, Ltd.
Positive and negative selection LYS5MX gene replacement cassettes for use in Saccharomyces cerevisiae
Authors: Ito‐Harashima Sayoko , McCusker John H.
Published: January 2004

Novel MX cassettes are described that contain the open reading frames (ORFs) of Saccharomyces cerevisiae or Candida albicans LYS5. The LYS5MX and CaLYS5MX cassettes, the targeting efficiencies of which are equivalent to those of other MX cassettes, are positively selected for Lys+ in a lys5 background. Unlike most of the other MX cassettes, the LYS5MX cassettes are also negatively selectable (α‐aminoadipate‐resistant), which will allow the use of the LYS5MX cassettes in plasmid shuffling and will also greatly facilitate marker recycling. Copyright © 2003 John Wiley & Sons, Ltd.
Phase Transition of a Dicyanamide with Rutile‐like Structure: Syntheses and Crystal Structures of α‐ and β‐Cd[N(CN)2]2
Authors: Jürgens Barbara , Irran Elisabeth , Höppe Henning A. , Schnick Wolfgang
Published: January 2004

Cadmium dicyanamide Cd[N(CN)2]2 was synthesized through aqueous ion exchange at room temperature. A reversible phase transition was detected by in situ X‐ray powder diffractometry above 55 °C. The crystal structures of both phases were determined by X‐ray powder diffraction (β‐Cd[N(CN)2]2: T = 22 °C, a = 621.60(3), b = 748.76(4), c = 770.21(5) pm, β = 91.784(3)°, P21/n (no. 14), Z = 2, wRp = 0.063, Rp = 0.050, RF = 0.059; α‐Cd[N(CN)2]2: T = 150 °C, a = 624.62(5), b = 752.92(6), c = 768.30(7) pm, Pnnm (no. 58), Z = 2, wRp = 0.083, Rp = 0.064, RF = 0.087). Both polymorphs consist of Cd2+ and bent planar [N(CN)2]— ions. α‐Cd[N(CN)2]2 crystallizes analogously to rutile and is isotypic with MII[N(CN)2]2(M = Mg, Cr, Mn, Co, Ni, Cu). The monoclinic low‐temperature polymorph β‐Cd[N(CN)2]2 is closely related to that of the orthorhombic high‐temperature polymorph α‐Cd[N(CN)2]2 by a translationengleiche transition of index 2.
Kristallstruktur des Zinkamids Zn[N(SiMe3)2]2
Authors: Margraf G. , Lerner H.‐W. , Bolte M. , Wagner M.
Published: January 2004

Crystal Structure of the Zinc Amide Zn[N(SiMe3)2]2

X‐ray quality crystals of Zn[N(SiMe3)2]2 (monoclinic, P21/c) are obtained by sublimation of the zinc amide Zn[N(SiMe3)2]2 at —30 °C in vacuo (300 torr). According to the result of the X‐ray structural analysis, Zn[N(SiMe3)2]2 contains an almost linear N‐Zn‐N unit with two short N‐Zn bonds.