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Selected AbstractsSedimentation as a tool for crystallization from protein mixturesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2006I. Dimitrov Abstract Crystals from apoferritin which is an iron-free form of protein ferritin were obtained from protein mixtures lysozyme/apoferritin using sedimentation under high gravity. Solution containing apoferritin at concentration as high as 5mg/ml in the presence of 25mg/ml lysozyme and overlaid on 5%(w/v) CdSO4 in 0,2M/L NaAC, pH=5 still favors apoferritin crystal formation under normal gravity conditions, but at apoferritin concentrations <0,5mg/ml (,1,14µM/L) in 25mg/ml (,1,71mM/L) lysozyme only the sedimentation in a centrifuge appears to be useful for separating the apoferritin molecules from the mixture followed by apoferritin crystallization in the same system. The very high molecule number ratio (,1:103) of two proteins is used to stress on the observed effect. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Coexistence of natural enemies in a multitrophic host,parasitoid systemECOLOGICAL ENTOMOLOGY, Issue 6 2004Michael B. Bonsall Abstract., 1. This study explored the temporal and spatial aspects of coexistence over many generations in a multispecies host,parasitoid assemblage. 2. The long-term interaction between the cabbage root fly, Delia radicum (Diptera: Anthomyiidae), and two of its natural enemies, Trybliographa rapae (Hymenoptera: Fitigidae) and Aleochara bilineata (Coleoptera: Staphylinidae), in a cultivated field at Silwood Park over 19 years was explored. 3. Although time series showed that the populations were regulated, the impact of the natural enemies was highly variable. Within-year determinants showed that the spatial response of the specialist parasitoid, T. rapae, was predominantly independent of host density while A. bilineata acted simply as a randomly foraging generalist parasitoid. 4. These findings are compared and contrasted with an earlier investigation of the same system when only the first 9 years of the time series were available. This study demonstrated the potential of long-term field studies for exploring hypotheses on population regulation, persistence, and coexistence. [source] Relative mutagenic potencies of several nucleoside analogs, alone or in drug pairs, at the HPRT and TK loci of human TK6 lymphoblastoid cells,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3-4 2007Meghan M. Carter Abstract Experiments were performed to investigate the impact of didanosine (ddI), lamivudine (3TC), and stavudine (d4T) on cell survival and mutagenicity in two reporter genes, hypoxanthine-guanine phosphoribosyltransferase (HPRT) and thymidine kinase (TK), using a cell cloning assay for assessing the effects of individual nucleoside analogs (NRTIs)/drug combinations in human TK6 B-lymphoblastoid cells. Three-day treatments with 0, 33, 100, or 300 ,M ddI, 3TC, or ddI-3TC produced positive trends for increased HPRT and TK mutant frequencies. While dose-related trends were too small to reach significance after treatments with d4T or d4T-3TC, pairwise comparisons with control cells indicated that exposure to 100 ,M d4T or d4T-3TC caused significant elevations in HPRT mutants. Measurements of mutagenicity in cells exposed to d4T (or d4T-3TC) were complicated by the cytotoxicity of this NRTI. Enhanced increases in mutagenic responses to combined NRTI treatments, compared with single drug treatments, occurred as additive to synergistic effects in the HPRT gene of cells exposed to 100 ,M ddI-3TC or 100 ,M d4T-3TC, and in the TK gene of cells exposed to 100 or 300 ,M ddI-3TC. Comparisons of these data to mutagenicity studies of other NRTIs in the same system (Meng Q et al. [2000c]: Proc Natl Acad Sci USA 97:12667,126671; Torres SM et al. [2007]: Environ Mol Mutagen) indicate that the relative mutagenic potencies for all drugs tested to date are: AZT-ddI > ddI-3TC > AZT-3TC , AZT-3TC-ABC (abacavir) > AZT ,ddI > d4T-3TC > 3TC > d4T , ABC. These collective data suggest that all NRTIs with antiviral activity against HIV-1 may cause host cell DNA damage and mutations, and impose a cancer risk. Environ. Mol. Mutagen., 2007. © 2007 Wiley-Liss, Inc. [source] Synthesis, Characterization and Electrochemistry of the Novel Dawson-Type Tungstophosphate [H4PW18O62]7, and First Transition Metal Ions DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2004Israel-Martyr Mbomekalle Abstract Following the synthesis of pure [H4PW18O62]7, (PW18), its derivatives monosubstituted with M (M = MoVI, VIV, VV, MnII, FeIII, CoII, NiII CuII and ZnII) were obtained. All compounds were characterized by elemental analysis, IR, UV/visible and 31P NMR spectroscopy. Their cyclic voltammetry properties were studied as a function of pH and systematically compared with those of their analogs derived from the symmetrical species, [P2W18O62]6,(P2W18). Comparison of the two unsubstituted precursors revealed that the merging of the first two waves of the monophosphate occurred in a less acidic medium than for the diphosphate. The observations point to the higher basicity of the reduced forms of PW18 compared with those of P2W18. The fingerprint pattern observed for ,2 -P2W17M derivatives in media of pH = 3 consisted of the splitting of the third W redox system into two one-electron closely spaced waves which is in contrast to the same system in ,1 -P2W17M. This peculiarity was also obtained for several of the present ,2 -PW17M systems in media of pH = 3 and confirmed that ,2 -substituted derivatives were indeed formed. The absence of this peculiar behavior in some other derivatives is consistent with smooth variations of acid-base properties from one derivative to the next. The electrocatalytic properties of all the compounds are illustrated by the reduction of nitrite by reduced PW18 and of nitrate by reduced ,2 -PW17Cu. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Euroethics,a database network on biomedical ethicsHEALTH INFORMATION & LIBRARIES JOURNAL, Issue 3 2006Ylva Gavel Background:,euroethics is a database covering European literature on ethics in medicine. It is produced within Eurethnet, a European information network on ethics in medicine and biotechnology. Objectives:, The aim of Euroethics is to disseminate information on European bioethical literature that may otherwise be difficult to find. Methods:, A collaboration model for pooling data from different centres was developed. The policy was to accomplish data uniformity, while still allowing for local differences in terms of software, indexing practices and resources. Records contributed to the database follow common standards in terms of data fields and indexing terms. The indexing terms derive from two thesauri, Thesaurus Ethics in the Life Sciences (TELS) and Medical Subject Headings (MeSH). Combining elements from search tools developed previously, the developers sought to find a technical solution optimized for this data model. An approach relying on a thesaurus database that is loaded along with the bibliographic database is described. Results and conclusions:, The present case study offers examples of possible approaches to several tasks often encountered in database development, such as: merging data from diverse sources, getting the most out of indexing terms used in a database, and handling more than one thesaurus in the same system. [source] Separate brain regions code for salience vs. valence during reward prediction in humansHUMAN BRAIN MAPPING, Issue 4 2007Jimmy Jensen Abstract Predicting rewards and avoiding aversive conditions is essential for survival. Recent studies using computational models of reward prediction implicate the ventral striatum in appetitive rewards. Whether the same system mediates an organism's response to aversive conditions is unclear. We examined the question using fMRI blood oxygen level-dependent measurements while healthy volunteers were conditioned using appetitive and aversive stimuli. The temporal difference learning algorithm was used to estimate reward prediction error. Activations in the ventral striatum were robustly correlated with prediction error, regardless of the valence of the stimuli, suggesting that the ventral striatum processes salience prediction error. In contrast, the orbitofrontal cortex and anterior insula coded for the differential valence of appetitive/aversive stimuli. Given its location at the interface of limbic and motor regions, the ventral striatum may be critical in learning about motivationally salient stimuli, regardless of valence, and using that information to bias selection of actions. Inc. Hum Brain Mapp, 2007. © 2006 Wiley-Liss, Inc. [source] Assessment of rainfall-runoff models based upon wavelet analysisHYDROLOGICAL PROCESSES, Issue 5 2007Stuart N. Lane Abstract A basic hypothesis is proposed: given that wavelet-based analysis has been used to interpret runoff time-series, it may be extended to evaluation of rainfall-runoff model results. Conventional objective functions make certain assumptions about the data series to which they are applied (e.g. uncorrelated error, homoscedasticity). The difficulty that objective functions have in distinguishing between different realizations of the same model, or different models of the same system, is that they may have contributed in part to the occurrence of model equifinality. Of particular concern is the fact that the error present in a rainfall-runoff model may be time dependent, requiring some form of time localization in both identification of error and derivation of global objective functions. We explore the use of a complex Gaussian (order 2) wavelet to describe: (1) a measured hydrograph; (2) the same hydrograph with different simulated errors introduced; and (3) model predictions of the same hydrograph based upon a modified form of TOPMODEL. The analysis of results was based upon: (a) differences in wavelet power (the wavelet power error) between the measured hydrograph and both the simulated error and modelled hydrographs; and (b) the wavelet phase. Power difference and wavelet phase were used to develop two objective functions, RMSE(power) and RMS(phase), which were shown to distinguish between simulated errors and model predictions with similar values of the commonly adopted Nash-Sutcliffe efficiency index. These objective functions suffer because they do not retain time, frequency or time-frequency localization. Consideration of wavelet power spectra and time- and frequency-integrated power spectra shows that the impacts of different types of simulated error can be seen through retention of some localization, especially in relation to when and the scale over which error was manifest. Theoretical objections to the use of wavelet analysis for this type of application are noted, especially in relation to the dependence of findings upon the wavelet chosen. However, it is argued that the benefits of localization and the qualitatively low sensitivity of wavelet power and phase to wavelet choice are sufficient to warrant further exploration of wavelet-based approaches to rainfall-runoff model evaluation. Copyright © 2006 John Wiley & Sons, Ltd. [source] Some methodological problems concerning nonisothermal kinetic analysis of heterogeneous solid,gas reactionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2001P. Budrugeac Isoconversional methods, those using only one curve , = ,(T) (, is the conversion degree and T is the temperature), and invariant kinetic parameter method were applied to estimate the kinetic parameters from the following nonisothermal data: (1) simulated TG curves for a single reaction; (2) TG curves for thermal degradation of PVC; and (3) TG curves for the dehydration of CaC2O4·H2O. The results obtained by applying various methods for the same system are compared and discussed. Finally, a procedure of kinetic analysis is suggested. Its application could lead to kinetic parameter values that can be used to predict either , = ,(t) curves for other heating rates or , = ,(T) curves for isothermal conditions. © 2001 John Wiley & Sons, Inc. Int J chem Kinet 33: 564,573, 2001 [source] Governance of social security regimes: Trends in SenegalINTERNATIONAL SOCIAL SECURITY REVIEW, Issue 3-4 2003Ahmadou Yéri Diop The main aim of this article is to analyse the Senegalese experience in the management of social security institutions. The keyword which occurs and reoccurs is autonomy. Except for Côte d'Ivoire, which has experimented with the same system since 2000, the Senegalese experience is unique in French-speaking sub-Saharan Africa. The article reviews the institutional pluralism which is another unique feature of the Senegalese situation, the genuine autonomy of management which exists and its results, illustrated by the example of the Social Security Fund. The results obtained in terms of financial stability, better quality of service and the installation of an efficient information system prove that this is the way of the future. Finally, the paper highlights the distribution of powers between the various bodies of the Fund. [source] ,The geriatric hospital felt like a backwater': aspects of older people's nursing in Britain, 1955,1980JOURNAL OF CLINICAL NURSING, Issue 19 2009Jane Brooks Aims and objectives., The aim of this article is to examine the experiences of ward-level nurses who cared for older people in general hospitals between 1955,1980. Background., There is very little published on the history of older adult nursing and no recent material from the United Kingdom. There are, however, the works of Cecily Hunter in Australia and Erica Roberts in Canada. It is the intention of this study to contribute to this important area of research. Design., This is an oral history project in which 20 nurses who had worked on older adults ward between 1955,1980 were interviewed. Methods., All the interviews were taped, transcribed and data-themed. Ethical clearance for the project was obtained from the University Ethics Committee and all participants were anonymised. Results., Many of the nurses found the experience very difficult, though there were exceptions. Several participants had worked on older adults ward during their training and then had never wanted to return. Most described a paucity of resources and longevity of staff on the wards. Conclusions., Using the sociological theory of Erving Goffman, this article introduces a novel method of understanding nursing history, although his ideas have been used in medical history. The value of his theories for this study is in the identification of nurses as being part of the same system as the patients themselves. Implications for contemporary policy, research and/or practice., For nurses to care effectively for their patients, nurses themselves must be valued. Subordination and regimentation tend to dehumanise the carers which, in turn, dehumanises the cared for. [source] Practical modeling of molecular systems with symmetriesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 9 2010Sergei Grudinin Abstract A new method for efficient modeling of macromolecular systems with symmetries is presented. The method is based on a hierarchical representation of the molecular system and a novel fast binary tree-based neighbor list construction algorithm. The method supports all types of molecular symmetry, including crystallographic symmetry. Testing the proposed neighbor list construction algorithm on a number of different macromolecular systems containing up to about 200,000 of atoms shows that (1) the current binary tree-based neighbor list construction algorithm scales linearly in the number of atoms for the central subunit, and sublinearly for its replicas, (2) the overall computational overhead of the method for a system with symmetry with respect to the same system without symmetry scales linearly with the cutoff value and does not exceed 50% for all but one tested macromolecules at the cutoff distance of 12 Ĺ. (3) the method may help produce optimized molecular structures that are much closer to experimentally determined structures when compared with the optimization without symmetry, (4) the method can be applied to models of macromolecules with still unknown detailed structure. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Analyzing software evolution through feature viewsJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 6 2006Orla Greevy Abstract Features encapsulate the domain knowledge of a software system and thus are valuable sources of information for a reverse engineer. When analyzing the evolution of a system, we need to know how and which features were modified to recover both the change intention and extent, namely which source artifacts are affected. Typically, the implementation of a feature crosscuts a number of source artifacts. To obtain a mapping between features and the source artifacts, we exercise the features and capture their execution traces. However, this results in large traces that are difficult to interpret. To tackle this issue we compact the traces into simple sets of source artifacts that participate in a feature's runtime behavior. We refer to these compacted traces as feature views. Within a feature view, we partition the source artifacts into disjoint sets of characterized software entities. The characterization defines the level of participation of a source entity in the features. We then analyze the features over several versions of a system and we plot their evolution to reveal how and which features were affected by code changes. We show the usefulness of our approach by applying it to a case study where we address the problem of merging parallel development tracks of the same system. Copyright © 2006 John Wiley & Sons, Ltd. [source] Energy Transfer Enables 1.53 ,m Photoluminescence from Erbium-Doped TiO2 Semiconductor Nanocrystals Synthesized by Ar/O2 Radio-Frequency Thermal PlasmaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Ji-Guang Li Highly crystalline, highly luminescent nanopowders of Er3+ -doped TiO2 have been successfully synthesized via one-step Ar/O2 radio-frequency thermal plasma processing. Energy transfer from the TiO2 host to Er3+ activators has been confirmed by combined means of UV-vis, excitation, and photoluminescence spectroscopies. As a consequence, bright photoluminescence at ,1.53 ,m was observed from the nanopowders either by directly exciting the Er3+ activator or by exciting the TiO2 host lattice. A comparative study shows that the nanopowder of the same system made via coprecipitation lacks the energy transfer. The plasma-generated nanopowders may thus find applications in optoelectronic devices. [source] Synthesis and structure elucidation of bromination products from dibromohomobenzonorbornadienes: high temperature bromination,Part 17,MAGNETIC RESONANCE IN CHEMISTRY, Issue 1 2005Cavit Kazaz Abstract The electrophilic addition of bromine to dibromohomobenzonorbornadiene derivatives at ,45 ± 5°C led to the formation of the rearranged and non-rearranged tetrabromides in a ratio of 6:4. However, high-temperature bromination of the same system in CCl4 at 77°C produced only non-rearranged products. The formation mechanism of the isomers and the role of the substituent on the rearrangement is discussed. The structure elucidation of the isomeric tetrabromides was achieved from NMR spectral data. The agreement between the calculated dihedral angles and the measured coupling constants is especially excellent. The ,-gauche effect is discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source] A novel lysis system in PM2, a lipid-containing marine double-stranded DNA bacteriophageMOLECULAR MICROBIOLOGY, Issue 6 2007Mart Krupovi Summary In this study we investigated the lysis system of the lipid-containing double-stranded DNA bacteriophage PM2 infecting Gram-negative marine Pseudoalteromonas species. We analysed wt and lysis-deficient phage-induced changes in the host physiology and ascribed functions to two PM2 gene products (gp) involved in lysis. We show that bacteriophage PM2 uses a novel system to disrupt the infected cell. The novelty is based on the following findings: (i) gp k is needed for the permeabilization of the cytoplasmic membrane and appears to play the role of a typical holin. However, its unique primary structure [53 aa, 1 transmembrane domain (TMD)] places it into a new class of holins. (ii) We have proposed that, unlike other bacteriophages studied, PM2 relies on lytic factors of the cellular origin for digestion of the peptidoglycan. (iii) gp l (51 aa, no TMDs) is needed for disruption of the outer membrane, which is highly rigidified by the divalent cations abundant in the marine environment. The gp l has no precedent in other phage lytic systems studied so far. However, the presence of open reading frame l-like genes in genomes of other bacterial viruses suggests that the same system might be used by other phages and is not unique to PM2. [source] Scale-dependence of movement rates in stream invertebratesOIKOS, Issue 1 2004Göran Englund We used analytical models and random walk simulations in a one-dimensional habitat to study the scale-dependence of migration rates in stream invertebrates. Our models predict that per capita migration rate is inversely proportional to patch length when patches are large compared to the scale of movements. When patches are small the scale-dependence is weaker and primarily determined by the length of individual movements (steps) relative to patch size. Laboratory experiments using isopods (Asellus aquaticus L.) and mayfly nymphs (Baetis sp.) confirmed that the strength of the scale-dependence decreased with increasing step length. For the case when step length distributions follow an exponential probability distribution, which is often the case for stream organisms, we provide a simple model that allows the scale-dependence to be predicted from the mean step length. We fitted this model to published field data on drift densities at different downstream distances from a net that blocks the drift from upstream areas. Agreement between model and data was excellent in most cases. We then used already published data on the length of induced drift movements to predict the scale-dependence that was observed in block experiments performed in the same system. Predicted and observed scale-dependence showed very close agreement. We conclude that our models and published data on drift distances can be used to calculate the expected scale-dependence of per capita emigration rates for a large number of taxa under a wide range of environmental conditions. [source] An efficient scheme for minimax solutions of multiple linear-quadratic controlOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 6 2005Wan-Lung Ng Abstract Optimal control is one of the most important methodologies for studies of dynamic systems in many areas of sciences, engineering and economics. Minimax optimal control is a special topic in the general framework of multiple optimal control problems. Minimax optimal control can be considered as a dynamic game with multiple players under the same system. In this paper, we develop a fast search for a minimax solution of multiple linear-quadratic control problems. The algorithm improves the existing solution scheme by adjusting the multiple weighting coefficients in each iteration and also including updates for step-size control. Copyright © 2005 John Wiley & Sons, Ltd. [source] An evaluation of the evidence for, and implications of, cytoplasmic nitrate homeostasisPLANT CELL & ENVIRONMENT, Issue 10 2002M. Y. Siddiqi Abstract A review of literature, reporting values of cytoplasmic/cytosolic [NO3,] in plant cells, identified two major areas of disagreement: (1) disparity in the absolute values within the same system, and (2) constancy versus variability in cytoplasmic/cytosolic [NO3,] with varying [NO3,]o. These differences are related to the techniques used by the different authors. Estimates of cytoplasmic [NO3,] by compartmental analysis and by cell fractionation were consistently higher than the estimates by NO3,selective microelectrodes and by techniques based upon in vivo and in vitro nitrate reductase activity (NRA). A model recognizing more than one cytoplasmic ionic pool would satisfactorily reconcile the differences in both aspects, i.e. absolute values and constancy. Compartmental analysis and cell fractionation techniques may measure the amount of NO3, in the cytoplasm as a whole (including organelles); by contrast, NO3, selective microelectrodes and NRA estimate only the cytosolic NO3, and, hence, may result in lower estimates. Thus, variable organellar pool(s) may maintain a constant cytosolic pool as estimated by microelectrodes. However, certain observations remain at odds with the notion of a constant cytosolic [NO3,]. [source] Land Tenure and Naming Systems in Aboriginal AustraliaTHE AUSTRALIAN JOURNAL OF ANTHROPOLOGY, Issue 1 2002Mark Harvey Naming systems play a prominent role in discussions of land tenure by Aboriginal people. Reference to one area of land and its owners is most commonly in terms of name ,X', whereas reference to another area of land and its owners is most commonly made in terms of name ,Y'. Much of the analytical literature examines how these names refer to groups of people. There is considerable dispute as to whether the reference of these names suffices to determine disjoint groupings of owners that can be described by the term ,clan'. This paper proposes that the analysis of linkages between names and areas of land should have priority over the analysis of linkages between names and groups of people. The evidence shows that the attachment of names to areas of land is more stable and consistent than their attachment to groups of people. There are differences in the ways that names attach to the landscape, and these differences are significant,they determine whether or not more than one name from the same system may be attached to an area of land. This paper focuses on two areas of Australia: the northern Kakadu-Oenpelli area and the Timber Creek area (both in the Northern Territory). It shows that naming systems identify disjunctive areas of land as the targets for claims of primary ownership in both areas. These disjunctive areas may reasonably be described with the translation term ,estates'. In the northern Kakadu-Oenpelli area, corresponding to these estates, there are disjunctive groupings of owners, which may be termed ,clans'. However, groupings of owners are not clearly disjunctive in the Timber Creek area, and there is little motivation for using the term ,clan'. This paper proposes that this difference reflects a general pattern in Aboriginal Australia, with naming systems stably and consistently identifying ,estates' across much of the continent. They do not identify ,clans' with equivalent stability and consistency. [source] Effects of food, proximity, and kinship on social behavior in ringtailed lemursAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2010Gena C. Sbeglia Abstract Efforts to understand the variation in primate social systems and their underlying interaction patterns have focused on both intrinsic and extrinsic factors. In the socioecological model, food distribution and abundance have been argued to be the primary influences on the social behavior of primate species. We examined the relationship of food resources and two intrinsic factors,kinship and proximity,with patterns of affiliative and agonistic relationships in two semi-free ranging ringtailed lemur, Lemur catta, social groups (N=14) at The Duke Lemur Center in Durham, NC. In analyzing these three factors concurrently within the same system, we attempt to establish their relative power in explaining the characteristics of social relationships. Patterns of affiliation and high-intensity agonism were best explained by kinship. Proximity also explained affiliation but did not explain agonism, which varied considerably between groups. The influence of food on social interactions was highly variable between the two groups and, therefore, did not convincingly account for the social behavior patterns we observed. Finally, different intensities of agonism have different patterns and should be analyzed individually. The variation between social groups makes it difficult for us to conclude that any one factor is primarily and universally responsible for patterns of social behavior in this species. Am. J. Primatol. 72:981,991, 2010. © 2010 Wiley-Liss, Inc. [source] Generalist predators in organically and conventionally managed grass-clover fields: implications for conservation biological controlANNALS OF APPLIED BIOLOGY, Issue 2 2008K Birkhofer Abstract Organically managed agroecosystems rely in part on biological control to prevent pest outbreaks. Generalist predators (Araneae, Carabidae and Staphylinidae) are a major component of the natural enemy community in agroecosystems. We assessed the seasonal dynamics of major generalist predator groups in conventionally and organically managed grass,clover fields that primarily differed by fertilisation strategy. We further established an experiment, manipulating the abundant wolf spider genus Pardosa, to identify the importance of these predators for herbivore suppression in the same system and growth period. Organic management significantly enhanced ground-active spider numbers early and late in the growing season, with potentially positive effects of plant cover and non-pest decomposer prey. However, enhancing spider numbers in the field experiment did not improve biological control in organically managed grass,clover fields. Similar to the survey results, reduced densities of Pardosa had no short-term effect on any prey taxa; however, spider guild structure changed in response to Pardosa manipulation. In the presence of fewer Pardosa, other ground-running spiders were more abundant; therefore, their impact on herbivore numbers may have been elevated, possibly cancelling increases in herbivore numbers because of reduced predation by Pardosa. Our results indicate positive effects of organic farming on spider activity density; however, our survey data and the predator manipulation experiment failed to find evidence that ground-running spiders reduced herbivore numbers. We therefore suggest that a positive impact of organic fertilisers on wolf spiders in grass,clover agroecosystems may not necessarily improve biological control when compared with conventional farming. [source] The interrelationship between productivity, plant species richness and livestock diet: a question of scale?APPLIED VEGETATION SCIENCE, Issue 2 2007Karin Süss Wisskirchen & Haeupler (1998) Abstract Question: What relationship exists between productivity, plant species richness and livestock diet? Are the results dependent on scale? Location: A sheep-grazed Koelerio-Corynephoretea sandy habitat of the northern upper Rhine (Germany) as a low productivity model system. Methods: The investigation was carried out for three years at a fine scale (2 m2) and for two years at a broad scale (79 m2). Productivity was measured by means of weighed above-ground phytomass for fine scale and colour-infrared (CIR) aerial photographs of the same system for fine and broad scales. For both scales, total numbers of vascular plant species and numbers of endangered vascular plant species were extracted from current vegetation relevés. Additionally, we obtained data on livestock diet (grazed phytomass, crude protein content). Results: Statistical analyses show an influence of the year on all variables; relationships between variables are not significant in every year. Species richness and number of endangered species are negatively related to productivity at fine scale while crude protein content and grazed phytomass are positively related to productivity. At the broad scale the diversity-productivity relationship shows a ,hump' with highest species numbers in middle pioneer stages; numbers of endangered species are highest in all pioneer stages. Conclusions: We found a strong impact of scale and year on the diversity-productivity relationship. It is inappropriate to analyse only small plots (2 m2), and it is necessary to study different years. This vegetation complex is dependent on grazing impact; thus there is an inversely proportional relationship between nature conservation value (high diversity) and livestock nutrition. [source] Potential antioxidant activity of celecoxib and amtolmetin guacyl: in vitro studiesAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 1 2007M. Kirkova Summary 1,In vitro studies of the potential antioxidant activity of the selective cyclo-oxygenase-2 inhibitor celecoxib and the non-steroid anti-inflammatory drug amtolmetin guacyl (AMG) were carried out. The study included experiments on the ability of these drugs to affect some indices of the oxidative stress [lipid peroxidation (LP), activity of antioxidant enzymes, glutathione (GSH) level] in rat stomach and colon mucosa and in liver. 2,Celecoxib and AMG did not change the activity of the enzymes GSH-peroxidase, oxidased glutathione (GSSG)-reductase and glucose-6-phosphate-dehydrogenase, as well as the GSH level in all tissue preparations. An increased superoxide dismutase (SOD) activity and a tendency to a decreased Fe/ascorbic acid-induced LP in stomach and colon mucosa were found, but only in the presence of AMG. 3,In the liver, both celecoxib and AMG decreased spontaneous and Fe/ascorbic acid-induced LP. SOD activity was enhanced only in the presence of AMG. 4,Experiments aimed at studying celecoxib and AMG in free oxygen radical-generating systems were also carried out. AMG and tolmetin (the main metabolite of AMG) inhibited OH, -provoked deoxyribose degradation in a Fenton system. Celecoxib had no effect on free radicals when tested in the same system. 5,In conclusion, the results of the present in vitro studies suggest that AMG and celecoxib possess antioxidant and metal-chelating abilities, which might contribute to their beneficial effects. [source] Mechanisms of adenosine-induced cytotoxicity and their clinical and physiological implicationsBIOFACTORS, Issue 1-4 2006Sharmila P. Seetulsingh-Goorah Abstract Extracellular ATP (ATPo) and adenosine are cytotoxic to several cancer cell lines, suggesting their potential use for anticancer therapy. Adenosine causes cytotoxicity, either when added exogenously or when generated from ATPo hydrolysis, via mechanisms which are not mutually exclusive and which involve, adenosine receptor activation, pyrimidine starvation and/or increases in intracellular S-adenosylhomocysteine: S-adenosylmethionine ratio. Given that adenosine also appears to protect against cytotoxicity via mechanisms including immunity against damage by oxygen free radicals, an understanding of the contribution of adenosine to ATPo-induced cytotoxicity is thus crucial, when considering any potential therapeutic use for these compounds. However, such an understanding has been largely hindered by the fact that many studies have not focused enough on the possibility that both ATPo and adenosine may mediate cytotoxicity in the same system. Such studies can benefit from use a range of ATPo concentrations when assessing the contribution of adenosine to ATPo-induced cytotoxicity. Whilst future molecular and pharmacological studies are needed to establish the nature of the cytotoxic adenosine receptor, it is possible that more than just one adenosine receptor type is involved and that the cytotoxic receptor(s) type is more likely to have a low affinity for adenosine. Activation of the adenosine receptor(s) would thus lead to cytotoxicity only at relatively high adenosine concentrations, while lower adenosine concentrations mediate non-cytotoxic physiological effects. [source] Acetate-inducible protein overexpression from the glnAp2 promoter of Escherichia coliBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2001William R. Farmer Abstract The Ntr regulon in Escherichia coli has previously been engineered to control the expression of a heterologous metabolic pathway. In this study, we reengineered the same system for protein production. In the absence of NRII (glnL gene product), we showed that glnAp2 can be an effective promoter for protein production that is inducible by exogenous acetate, but both the induction ratio and the range of modulation are low. To deal with this issue, we inactivated phosphotransacetylase (pta gene product), which disrupts the acetate pathway and denies the cell the ability to synthesize acetate. With this additional modification, gene expression from glnAp2 can be controlled by directly adding acetate into the growth medium. Using a lacZ reporter fusion, we found that glnAp2 induction was modulatable over a range of potassium acetate concentrations, and the induction/noninduction ratio increased to 77 in the absence of pta. The extracellular acetate required for maximal induction is lower than the concentration that causes toxicity, and thus growth inhibition by acetate addition was not a matter of concern. Furthermore, compared to the Ptac promoter, overexpression of a model protein using the modified glnAp2 promoter system did not cause significant growth inhibition, although a higher level of protein expression was achieved. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 504,509, 2001. [source] Mechanism of Charging of Au Atoms and Nanoclusters on Li Doped SiO2/Mo(112) FilmsCHEMPHYSCHEM, Issue 2 2010Umberto Martinez Dr. Abstract We present the results of supercell DFT calculations on the adsorption properties of Au atoms and small clusters (Aun, n,5) on a SiO2/Mo(112) thin film and on the same system modified by doping with Li atoms. The adsorbed Li atoms penetrate into the pores of the silica film and become stabilized at the interface where they donate one electron to the Mo metal. As a consequence, the work function of the Li-doped SiO2/Mo(112) film is reduced and results in modified adsorption properties. In fact, while on the undoped SiO2/Mo(112) film Au interacts only very weakly, on the Li-doped surface Au atoms and clusters bind with significant bond strengths. The calculations show that this is due to the occurrence of an electron transfer from the SiO2/Mo(112) interface to the adsorbed gold. The occurrence of the charge transfer is related to the work function of the support but also to the possibility for the silica film to undergo a strong polaronic distortion. [source] Regulation of GluR2 promoter activity by neurotrophic factors via a neuron-restrictive silencer elementEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2000Stefan Brené Abstract The AMPA glutamate receptor subunit GluR2, which plays a critical role in regulation of AMPA channel function, shows altered levels of expression in vivo after several chronic perturbations. To evaluate the possibility that transcriptional mechanisms are involved, we studied a 1254-nucleotide fragment of the 5,-promoter region of the mouse GluR2 gene in neural-derived cell lines. We focused on regulation of GluR2 promoter activity by two neurotrophic factors, which are known to be altered in vivo in some of the same systems that show GluR2 regulation. Glial-cell line derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) both induced GluR2 promoter activity. This was associated with increased expression of endogenous GluR2 immunoreactivity in the cells as measured by Western blotting. The effect of GDNF and BDNF appeared to be mediated via a NRSE (neuron-restrictive silencer element) present within the GluR2 promoter. The response to these neurotrophic factors was lost upon mutating or deleting this site, but not several other putative response elements present within the promoter. Moreover, overexpression of REST (restrictive element silencer transcription factor; also referred to as NRSF or neuron restrictive silencer factor), which is known to act on NRSEs in other genes to repress gene expression, blocked the ability of GDNF to induce GluR2 promoter activity. However, GDNF did not alter endogenous levels of REST in the cells. Together, these findings suggest that GluR2 expression can be regulated by neurotrophic factors via an apparently novel mechanism involving the NRSE present within the GluR2 gene promoter. [source] Psychological Stress and Oxidative Damage in Lymphocytes of Aerobically Fit and Unfit Individuals,JOURNAL OF APPLIED BIOBEHAVIORAL RESEARCH, Issue 1 2008Kelly Z. Knickelbein Habitual aerobic exercise has a beneficial effect on many systems of the body, and psychological stress has a negative influence on several of the same systems. One possible pathway is through those systems that account for the detrimental effects of stress; by buffering these harmful effects, exercise may reduce the consequences of stress. This study examined increased resistance of cells to stress-induced oxidative damage as a result of fitness. Forty healthy participants were assigned to either a stress group or a no-stress control group, and measures of stress and oxidative damage were collected. Variation in fitness level across participants was also measured. Oxidative damage increased as a function of stress, but this was not buffered by fitness level. These results should be interpreted with caution because of the small sample size and the limited variability of cardiorespiratory fitness levels in the sample. [source] Crossregulation of NF-,B by the APC/GSK-3,/,-catenin pathwayMOLECULAR CARCINOGENESIS, Issue 3 2004Jiong Deng Abstract Glycogen synthase kinase-3, (GSK-3,) and adenomatous polyposis coli (APC) play an important role in the regulation of ,-catenin. Inhibition of or defects in their functions can lead to activation of ,-catenin. ,-catenin has been recently found to interact with and inhibit nuclear factor kappa B (NF-,B). However, the regulatory roles of GSK-3,/APC on the NF-,B signaling pathway are unknown because of their diverse effects. In this study, we investigated whether GSK-3,/APC might regulate NF-,B activity through ,-catenin. We found that inhibition of GSK-3, suppressed NF-,B activity, whereas reexpression of APC restored NF-,B activity in APC mutated cells. The regulatory effects were through ,-catenin because depletion of ,-catenin with small interfering RNA (siRNA) in the same systems reversed the effects. The regulatory relationship was further supported by the analysis of primary breast tumor tissues in vivo in which NF-,B target TRAF1 was inversely correlated with activated ,-catenin. Thus, APC/GSK-3,, through ,-catenin, may crossregulate NF-,B signaling pathway. © 2004 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||