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Weakly
Kinds of Weakly Terms modified by Weakly Selected AbstractsTitelbild: Kinetics of Thiol/Disulfide Exchange Correlate Weakly with the Restoring Force in the Disulfide Moiety (Angew. Chem.ANGEWANDTE CHEMIE, Issue 38 200938/2009) Durch Erhöhung der Spannung in einer Reihe von makrocyclischen Disulfiden wurde gezeigt, dass die Kinetik des Thiol-Disulfid-Austauschs unabhängig von der Kraft ist. Dieser scheinbar der Intuition widersprechende Befund, dass das Ziehen an einem Molekül dessen Fragmentierung nicht beschleunigt, wird von R. Boulatov et,al. auf S.,7174,ff. vorgestellt und ist in Einklang mit dem SN2-Mechanismus des Thiol-Disulfid-Austauschs und dem einfachsten chemomechanischen Kinetikmodell. [source] Kinetics of Thiol/Disulfide Exchange Correlate Weakly with the Restoring Force in the Disulfide Moiety,ANGEWANDTE CHEMIE, Issue 38 2009Timothy Streckübungen: Nach Experimenten und DFT-Studien an zunehmend gespannten makrocyclischen Disulfiden ist die Kinetik des Thiol-Disulfid-Austauschs von der Rückstellkraft der Disulfideinheit unabhängig. Dies ist in Einklang mit dem SN2-Mechanismus des Thiol-Disulfid-Austauschs und erkärt die Beschleunigung der Disulfid-Reduktion bei der mechanischen Streckung bestimmter Proteine. [source] Is Functional Capacity Related to Left Atrial Contractile Function in Nonobstructive Hypertrophic Cardiomyopathy?CONGESTIVE HEART FAILURE, Issue 5 2005Yukitaka Shizukuda MD The mechanisms underlying reduced exercise capacity in patients with nonobstructive hypertrophic cardiomyopathy (NHCM) could include perturbations of ventricular relaxation, diastolic compliance, or compensatory atrial systolic function. We hypothesized that a loss of atrial contractility in NHCM patients leads to reduced functional capacity. To test this hypothesis, we compared resting noninvasive left atrial ejection phase indices in 49 consecutive patients with NHCM (ages 36±10 years; 41% female) and normal left ventricular ejection fraction (mean, 68%±8%) with objective metabolic exercise parameters. Left atrial active emptying fraction, ejection force, and kinetic energy failed to predict exercise capacity. Only left atrial total and active emptying volumes correlated weakly with minute volume/CO2 production slope (r=0.31 and r=0.33; p<0.05 for both). Furthermore, when subjects were stratified by New York Heart Association symptomatology, exercise parameters,but not atrial contractility,differed between groups. These data, obtained at rest, fail to suggest that NHCM-related heart failure symptoms are due to an atrial myopathy. [source] Pre-activation of retinoid signaling facilitates neuronal differentiation of mesenchymal stem cellsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2010Yang Bi Mesenchymal stem cells (MSCs) can differentiate into neurons in an appropriate cellular environment. Retinoid signaling pathway is required in neural development. However, the effect and mechanism through retinoid signaling regulates neuronal differentiation of MSCs are still poorly understood. Here, we report that all-trans-retinoic acid (ATRA) pre-induction improved neuronal differentiation of rat MSCs. We found that, when MSCs were exposed to different concentrations of ATRA (0.01,100 ,mol/L) for 24 h and then cultured with modified neuronal induction medium (MNM), 1 ,mol/L ATRA pre-induction significantly improved neuronal differentiation efficiency and neural-cell survival. Compared with MNM alone induced neural-like cells, ATRA/MNM induced cells expressed higher levels of Nestin, neuron specific enolase (NSE), microtubule-associated protein-2 (MAP-2), but lower levels of CD68, glial fibrillary acidic protein (GFAP), and glial cell line-derived neurotrophic factor(GDNF), also exhibited higher resting membrane potential and intracellular calcium concentration, supporting that ATRA pre-induction promotes maturation and function of derived neurons but not neuroglia cells from MSCs. Endogenous retinoid X receptors (RXR) RXR, and RXR, (and to a lesser extent, RXR,) were weakly expressed in MSCs. But the expression of RAR, and RAR, was readily detectable, whereas RAR, was undetectable. However, at 24 h after ATRA treatment, the expression of RAR,, not RAR, or RAR,, increased significantly. We further found the subnuclear redistribution of RAR, in differentiated neurons, suggesting that RAR, may function as a major mediator of retinoid signaling during neuronal differentiation from MSCs. ATRA treatment upregulated the expression of Vimentin and Stra13, while it downregulated the expression of Brachyury in MSCs. Thus, our results demonstrate that pre-activation of retinoid signaling by ATRA facilitates neuronal differentiation of MSCs. [source] Debt-Relief Effectiveness and Institution-BuildingDEVELOPMENT POLICY REVIEW, Issue 5 2009Andrea F. Presbitero This article provides new evidence on the effects of recent debt-relief programmes on different macroeconomic indicators in developing countries, focusing on the Heavily Indebted Poor Countries (HIPCs). The relationship between debt relief and institutional change is also investigated to assess whether donors are moving towards ex-post governance conditionality. Results show that debt relief is only weakly associated with subsequent improvements in economic performance but is correlated with increasing domestic debt which undermines the positive achievements in reducing external debt service. There is also evidence that donors are moving towards a more sensible allocation of debt forgiveness, rewarding countries which have better policies and institutions. [source] Development of motor speed and associated movements from 5 to 18 yearsDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2010THEO GASSER PHD Aim, To study the development of motor speed and associated movements in participants aged 5 to 18 years for age, sex, and laterality. Method, Ten motor tasks of the Zurich Neuromotor Assessment (repetitive and alternating movements of hands and feet, repetitive and sequential finger movements, the pegboard, static and dynamic balance, diadochokinesis) were administered to 593 right-handed participants (286 males, 307 females). Results, A strong improvement with age was observed in motor speed from age 5 to 10, followed by a levelling-off between 12 and 18 years. Simple tasks and the pegboard matured early and complex tasks later. Simple tasks showed no associated movements beyond early childhood; in complex tasks associated movements persisted until early adulthood. The two sexes differed only marginally in speed, but markedly in associated movements. A significant laterality (p<0.001) in speed was found for all tasks except for static balance; the pegboard was most lateralized, and sequential finger movements least. Associated movements were lateralized only for a few complex tasks. We also noted a substantial interindividual variability. Interpretation, Motor speed and associated movements improve strongly in childhood, weakly in adolescence, and are both of developmental relevance. Because they correlate weakly, they provide complementary information. [source] Quality of life and health-related quality of life of adolescents with cerebral palsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 7 2007Peter L Rosenbaum MD FRCP(C) This study assessed quality of life (QOL) and health-related quality of life (HRQOL) of 203 adolescents with cerebral palsy (111 males, 92 females; mean age 16y [SD 1y 9mo]). Participants were classified using the Gross Motor Function Classification System (GMFCS), as Level I (n=60), Level II (n=33), Level III (n=28), Level IV (n=50), or Level V (n=32). QOL was assessed by self (66.5%) or by proxy (33.5%) with the Quality of Life Instrument for People With Developmental Disabilities, which asks about the importance and satisfaction associated with the QOL domains of Being, Belonging, and Becoming; HRQOL was captured through proxy reports with the Health Utilities Index, Mark 3 (HUI3), which characterizes health in terms of eight attributes, each having five or six ordered levels of function. GMFCS level was not a source of variation for QOL domain scores but was significantly associated with the eight HRQOL attributes and overall HUI3 utility scores (p<0.05). Some QOL domain scores varied significantly by type of respondent (self vs proxy; p<0.05). Overall HUI3 utility values were significantly but weakly correlated with QOL Instrument scores for Being (r=0.37), Belonging (r=0.17), Becoming (r=0.20), and Overall QOL (r=0.28), and thus explain up to 14% of the variance (r2). These findings suggest that although QOL and HRQOL are somewhat related conceptually, they are different constructs and need to be considered as separate dimensions of the lives of people with functional limitations. [source] Does plant richness influence animal richness?: the mammals of Catalonia (NE Spain)DIVERSITY AND DISTRIBUTIONS, Issue 4 2004Bradford A. Hawkins ABSTRACT Although it has long been held that plant diversity must influence animal diversity, the nature of this relationship remains poorly understood at large spatial scales. We compare the species richness patterns of vascular plants and mammals in north-eastern Spain using a 100-km2 grain size to examine patterns of covariation. We found that the total mammal richness pattern, as well as those of herbivores and carnivores considered separately, only weakly corresponded to the pattern of plants. Rather, mammal richness was best described by climatic variables incorporating water inputs, and after adding these variables to multiple regression models, plant and mammal richness were virtually independent. We conclude that the observed association, although weak, is explained by shared responses of both groups to climate, and thus, plant richness has no influence on the richness pattern of Catalan mammals. [source] Asymmetric one-storey elastic systems with non-linear viscous and viscoelastic dampers: Earthquake responseEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4 2003Wen-Hsiung Lin Abstract Investigated are earthquake responses of one-way symmetric-plan, one-storey systems with non-linear fluid viscous dampers (FVDs) attached in series to a linear brace (i.e. Chevron or inverted V-shape braces).Thus, the non-linear damper is viscous when the brace is considered rigid or viscoelastic (VE) when the brace is flexible. The energy dissipation capacity of a non-linear FVD is characterized by an amplitude-dependent damping ratio for an energy-equivalent linear FVD, which is determined assuming the damper undergoes harmonic motion. Although this formulation is shown to be advantageous for single-degree-of-freedom (SDF) systems, it is difficult to extend its application to multi-degree-of-freedom (MDF) systems for two reasons: (1) the assumption that dampers undergo harmonic motion in parameterizing the non-linear damper is not valid for its earthquake-induced motion of an MDF system; and (2) ensuring simultaneous convergence of all unknown amplitudes of dampers is difficult in an iterative solution of the non-linear system. To date, these limitations have precluded the parametric study of the dynamics of MDF systems with non-linear viscous or VE dampers. However, they are overcome in this investigation using concepts of modal analysis because the system is weakly non-linear due to supplemental damping. It is found that structural response is only weakly affected by damper non-linearity and is increased by a small amount due to bracing flexibility. Thus, the effectiveness of supplemental damping in reducing structural responses and its dependence on the planwise distribution of non-linear VE dampers were found to be similar to that of linear FVDs documented elsewhere. As expected, non-linear viscous and VE dampers achieve essentially the same reduction in response but with much smaller damper force compared to linear dampers. Finally, the findings in this investigation indicate that the earthquake response of the asymmetric systems with non-linear viscous or VE dampers can be estimated with sufficient accuracy for design applications by analysing the same asymmetric systems with all non-linear dampers replaced by energy-equivalent linear viscous dampers. Copyright © 2003 John Wiley & Sons, Ltd. [source] Beyond macronutrients: element variability and multielement stoichiometry in freshwater invertebratesECOLOGY LETTERS, Issue 12 2006Roxanne Karimi Abstract We contrasted concentrations of macronutrients (C, N and P), essential (As, Cu, Zn and Se) and non-essential metals (Pb, Hg and Cd) in invertebrates across five lakes and June to October in one lake. We predicted that somatic concentrations of tightly regulated elements would be less variable than weakly and unregulated elements. Within each taxon, variation was lowest in macronutrients, intermediate in essential micronutrients, and highest in non-essential metals, which corresponded in rank to homeostatic regulation strength for the same elements calculated from the literature. Hence, homeostatic regulation may strongly influence variation in element concentrations of biota in situ. Of the individual elements, only taxonomic differences in C and N were consistent across lakes and over a season. Nevertheless, canonical discriminant analyses successfully discriminated among taxa based on taxonomic multielement composition. Thus, relative taxonomic differences in multielement composition appear more informative than absolute stoichiometric formulae when considering the role of inherently variable trace elements in ecological investigations. [source] GMM with Weak IdentificationECONOMETRICA, Issue 5 2000James H. Stock This paper develops asymptotic distribution theory for GMM estimators and test statistics when some or all of the parameters are weakly identified. General results are obtained and are specialized to two important cases: linear instrumental variables regression and Euler equations estimation of the CCAPM. Numerical results for the CCAPM demonstrate that weak-identification asymptotics explains the breakdown of conventional GMM procedures documented in previous Monte Carlo studies. Confidence sets immune to weak identification are proposed. We use these results to inform an empirical investigation of various CCAPM specifications; the substantive conclusions reached differ from those obtained using conventional methods. [source] Entrepreneurial Founder Teams: Factors Associated with Member Entry and ExitENTREPRENEURSHIP THEORY AND PRACTICE, Issue 2 2003Deniz Ucbasaran This exploratory study provides a review of the neglected area of entrepreneurial founder team turnover. A novel distinction is made between entrepreneurial founder team member entry and team member exit. Ninety owner-managed ventures were monitored between 1990 and 2000. Presented hypotheses relating to a team's human capital were explored using multivariate logistic regression analysis. Variables associated with entry were found not to be the same as those associated with exit. The size of the founding team was significantly negatively associated with subsequent team member entry. The link between team turnover and entrepreneurial team heterogeneity was mixed. Functional heterogeneity was weakly significantly positively associated with team member entry. Heterogeneity of prior entrepreneurial experience was significantly positively associated with team member exit. In addition, family firms were significantly negatively associated with team member exit. The average age of the team was not significantly associated with team member entry or exit. Additional insights in future research may be gathered if a broader definition of team turnover (i.e., considering team member entry and exit) is considered. Practitioner awareness of the different factors associated with team member entry and exit may encourage them to provide assistance, which facilitates the team building process over time in developing firms. Promising areas for additional research are highlighted. [source] Frameshift mutations induced by four isomeric nitroacridines and their des-nitro counterpart in the lacZ reversion assay in Escherichia coliENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2006George R. Hoffmann Abstract Acridines are well-known as compounds that intercalate noncovalently between DNA base pairs and induce ±1 frameshift mutations at sites of monotonous repeats of a single base. Reactive derivatives of acridines, including acridine mustards and nitroacridines, form covalent adducts in DNA and exhibit mutagenic properties different from the simple intercalators. We compared the frameshift mutagenicity of the cancer chemotherapy drug nitracrine (1-nitro-9-(3,-dimethylaminopropylamino)-acridine), its des-nitro counterpart 9-(3,-dimethylaminopropylamino)-acridine (DAPA), and its 2-, 3-, and 4-nitro isomers (2-, 3-, and 4-nitro-DAPA) in the lacZ reversion assay in Escherichia coli. DAPA is a simple intercalator, much like the widely studied 9-aminoacridine. It most strongly induced ±1 frameshift mutations in runs of guanine residues and more weakly induced ,1 frameshifts in a run of adenine residues. A nitro group in the 1, 3, or 4 position of DAPA reduced the yield of ±1 frameshift mutations. DAPA weakly induced ,2 frameshifts in an alternating CG sequence. In contrast, nitracrine and its 3-nitro isomer resembled the 3-nitroacridine Entozon in effectively inducing ,2 frameshift mutations. The 2- and 4-nitro isomers were less effective than the 1- and 3-nitro compounds in ,2 frameshift mutagenesis. The results are interpreted with respect to intercalation, steric interactions, effects of base strength on DNA binding, enzymatic processing, and a slipped mispairing model of frameshift mutagenesis. Environ. Mol. Mutagen., 2006. © 2005 Wiley-Liss, Inc. [source] Structure,activity analysis of the potentiation by aminothiols of the chromosome-damaging effect of bleomycin in G0 human lymphocytesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2001George R. Hoffmann Abstract The radioprotective aminothiols 2-[(aminopropyl)amino] ethanethiol (WR-1065) and cysteamine (CSM) potentiate the induction of chromosomal damage by the radiomimetic compound bleomycin (BLM) in G0 human lymphocytes. To investigate the mechanism of potentiation, we measured the clastogenic activity of BLM in the cytokinesis-block micronucleus assay in the presence and absence of amines, thiols, and aminothiols. The hydroxy analog of WR-1065, 2-(3-aminopropylamino) ethanol (WR-OH), potentiates BLM only slightly, indicating the critical nature of the thiol group. As thiols, WR-1065 and CSM may donate electrons for the activation of Fe+2 -BLM or for the regeneration of Fe+2 -BLM from inactive Fe+3 -BLM. The amines putrescine, spermidine, and spermine all potentiate BLM, but they are weaker potentiators than the aminothiols, and they are effective only at high concentrations. Their activity, like that of WR-OH, is probably a consequence of conformational alteration of DNA. Dithioerythritol (DTE) and 2-mercaptoethanol (2-ME), thiols lacking an amino group, are less effective potentiators of BLM than are the aminothiols. The thiol group of WR-1065 and CSM is therefore essential, but insufficient, for explaining the strong enhancement of BLM activity. The cationic nature of CSM and WR-1065, conferred by the amino groups, evidently concentrates the active thiol function at the site of BLM action on DNA. As expected on this basis, the diamine WR-1065 is a more effective potentiator of BLM than is the monoamine CSM, whereas cysteine and N -acetylcysteine (NAC), which lack a net positive charge, potentiate BLM only weakly. These studies suggest that potentiation of the clastogenic action of BLM by aminothiols can be explained by the combination of a thiol-mediated redox mechanism and an amine-mediated targeting of the thiol function to DNA. Environ. Mol. Mutagen. 37:117,127, 2001 © 2001 Wiley-Liss, Inc. [source] Novel microbial diversity adherent to plant biomass in the herbivore gastrointestinal tract, as revealed by ribosomal intergenic spacer analysis and rrs gene sequencingENVIRONMENTAL MICROBIOLOGY, Issue 4 2005Ross Larue Summary It is well recognized that a dynamic biofilm develops upon plant biomass in the herbivore gastrointestinal tract, but this component of the microbiome has not previously been specifically sampled, or directly compared with the biodiversity present in the planktonic fraction of digesta. In this study, the digesta collected from four sheep fed two different diets was separated into three fractions: the planktonic phase, and the microbial populations either weakly or tightly adherent to plant biomass. The community DNA prepared from each fraction was then subjected to both ribosomal intergenic spacer analysis (RISA) and denaturing gradient gel electrophoresis (DGGE). Both types of analysis showed that dietary factors influence community structure, and that the adherent fractions produced more complex profiles. The RIS-clone libraries prepared from the planktonic and adherent populations were then subjected to restriction fragment length polymorphism (RFLP) and DNA sequence analyses, which resulted in a far greater degree of discrimination among the fractions. Although many of the sequenced clones from the adherent populations were assigned to various clusters within the low G+C Gram-positive bacteria, the clone libraries from animals consuming an all-grass diet were largely comprised of novel lineages of Clostridium, while in animals consuming the starch-containing diet, Selenomonas and Ruminococcus spp. were the dominant low G+C Gram-positive bacteria. Additionally, the libraries from hay-fed animals also contained clones most similar to asaccharolytic Clostridia, and other Gram-positive bacteria that specialize in the transformation of plant phenolic compounds and the formation of cinnamic, phenylacetic and phenylpropionic acids. These results reveal, for the first time, the phylogeny of adherent subpopulations that specialize in the transformation of plant lignins and other secondary compounds, which potentiate polysaccharide hydrolysis by other members of the biofilm. [source] Toxicity assessment of reference and natural freshwater sediments with the LuminoTox assayENVIRONMENTAL TOXICOLOGY, Issue 4 2006P. M. Dellamatrice Abstract We examined the possibility of adapting the LuminoTox, a recently-commercialized bioanalytical testing procedure initially developed for aqueous samples, to assess the toxic potential of sediments. This portable fluorescent biosensor uses photosynthetic enzyme complexes (PECs) to rapidly measure photosynthetic efficiency. LuminoTox testing of 14 CRM (Certified Reference Material) sediments was first undertaken with (1) a "solid phase assay" (Lum-SPA) in which PECs are in intimate contact with sediment slurries for a 15 min exposure period and (2) an elutriate assay (Lum-ELU) in which PECs are exposed for 15 min to sediment water elutriates. CRM sediment toxicity data were then compared with those generated with the Microtox Solid Phase Assay (Mic-SPA). A significant correlation (P < 0.05) was shown to exist between Lum-SPA and Mic-SPA, indicating that both tests display a similar toxicity response pattern for CRM sediments having differing contaminant profiles. The sediment elutriate Lum-ELU assay displayed toxicity responses (i.e. measurable IC20s) for eight of the 14 CRM sediments, suggesting that it is capable of determining the presence of sediment contaminants that are readily soluble in an aqueous elutriate. Lum-SPA and Mic-SPA bioassays were further conducted on 12 natural freshwater sediments and their toxicity responses were more weakly, yet significantly, correlated. Finally, Lum-SPA testing undertaken with increasing mixtures of kaolin clay confirmed that its toxicity responses, in a manner similar to those reported for the Mic-SPA assay, are also subject to the influence of grain size. While further studies will be required to more fully understand the relationship between Lum-SPA assay responses and the physicochemical makeup of sediments (e.g., grain size, combined presence of natural and anthropogenic contaminants), these preliminary results suggest that LuminoTox testing could be a useful screen to assess the toxic potential of solid media. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 395,402, 2006. [source] Cytotoxicity assessment of gliotoxin and penicillic acid in Tetrahymena pyriformisENVIRONMENTAL TOXICOLOGY, Issue 2 2006C. Gräbsch Abstract Various studies have documented the associations between mold exposure and effects on health. Mycotoxins, which occur in spores and mold fragments, can be involved in processes that have pathological effects, such as adynamia of the immune system, recurrent infections of the respiratory tract, or asthma. Using Tetrahymena pyriformis, a single-cell organism well established as a suitable model for human respiratory epithelium-cell functionalities, we investigated dose,response relationships of the mycotoxins gliotoxin and penicillic acid. Our study focused on the viability (cell count, MTT assay), energy levels (adenosine-5,-triphosphate content), energy-providing processes (MTT reduction per cell), and cell respiration (oxygen consumption). Both mycotoxins acted as cytotoxins in a dose-dependent manner. Gliotoxin had a stronger inhibitory effect (EC50 0.38 ,M) than did penicillic acid (EC50 343.19 ,M). The energy-providing processes were not inhibited or were only weakly inhibited under the influence of gliotoxin, whereas penicillic acid caused stimulation of the physiological parameters. Summarizing the results, it is clear that the two investigated mycotoxins must have different modes of action. They are not only different in the strength of their toxic effects but also in a variety of physiological aspects. In addition, T. pyriformis showed differences in its ability to overcome the negative effects of particular mycotoxin exposures. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 111,117, 2006. [source] Evaluating polycyclic aromatic hydrocarbons using a yeast bioassayENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007Abeer Alnafisi Abstract Sixteen polycyclic aromatic hydrocarbons (PAHs) were evaluated for the ability to activate aryl hydrocarbon (Ah) receptor signaling in a yeast-based bioassay. Individual PAHs were classified as inactive or as weakly, moderately, or strongly active based on induction of human Ah receptor signaling. Indeno[1,2,3- cd]pyrene, chrysene, benzo[a]anthracene, benzo[a]pyrene, benzo[j]fluoranthene, and benzo[k]fluoranthene were the most potent activators of human Ah receptor signaling. Various mixtures of PAHs had additive or synergistic effects in the bioassay. Environmental samples from the New Orleans (Louisiana, USA) and Detroit (Michigan, USA) areas that were previously analyzed for PAH composition and quantity were tested in this bioassay. Weak but statistically significant relationships were found when the analytically measured levels of PAHs were correlated with sample dilutions that gave 25% effective concentration signaling levels in the Ah receptor assay. We conclude that this Ah receptor signaling assay may be useful for preliminary biomonitoring of samples for PAHs and other Ah receptor ligands. [source] Characterizing sediment acid volatile sulfide concentrations in European streamsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007G. Allen Burton Abstract Sediment acid volatile sulfide (AVS) concentrations were measured in wadeable streams of a wide variety of ecoregions of western Europe (84 sites in 10 countries and nine ecoregions) to better understand spatial distribution and ecoregion relationships. Acid volatile sulfide has been shown to be a major factor controlling the bioavailability and toxicity of many common trace metals, such as Cd, Cu, Ni, Pb, and Zn. Sediment characteristics varied widely. The ratio of the sum of the simultaneously extracted metals (SEM) to AVS ranged from 0.03 to 486.59. The ,SEM-AVS ranged from ,40.02 to 17.71 ,mol/g. On a regional scale, sediment characteristics such as dominant parent soil material showed significant trends in AVS distribution and variation by ecoregion. Total Fe and Mn were correlated weakly with SEM concentrations. Three AVS model approaches (i.e., the SEMAVS ratio, SEM-AVS difference, and carbon normalization) were compared at threshold exceedance levels of SEM/AVS > 9, SEM-AVS > 2, and SEM-AVS/foc > 150 ,mol/g organic carbon (OC). Only 4.76% of the sediments exceeded all three AVS thresholds; 22.6% of the sediments exceeded two models; and 13% of the sediments exceeded one model only. Using the SEM:AVS, SEM-AVS, and fraction of organic carbon models, and including site-specific data and regional soil characteristics, ecoregions 1 (Portugal), 3 (Italy), 4 (Switzerland), and 9 (Belgium/Germany) had the highest potential metals toxicity; ecoregions 13 and 8 (Belgium/France) showed the lowest potential toxicity. However, because AVS can vary widely spatially and temporally, these data should not be considered as representative of the sampled ecoregions. The general relationship between AVS levels and sediment characteristics provides some predictive capability for wadeable streams in the European ecoregions. [source] Incubation Behaviour in Northern Lapwings: Nocturnal Nest Attentiveness and Possible Importance of Individual Breeding QualityETHOLOGY, Issue 3 2004Terje Lislevand Previous studies of sex roles in the polygynous Northern Lapwing Vanellus vanellus have shown that males incubate less than females, perhaps suggesting that sexual selection is important in shaping the parental behaviour of this species. The purpose of this study was to (1) examine for the first time the possibility that males compensate for low diurnal nest attentiveness by increasing their nocturnal assistance and (2) evaluate the hypotheses that sexual selection and individual breeding quality determines incubation behaviour in lapwings. Males were never found incubating at night in 19 nests, although median diurnal male attentiveness was 15.3% in 16 of the same pairs. Nor were there any differences among monogamous and polygynous males in the time spent in four categories of behaviour (incubation, guarding, maintenance and mating activities). The time males spent in mating and incubation behaviours was weakly negatively correlated, and the time spent incubating varied considerably among males (0,74%). Further, female body condition was positively related with male nest attentiveness and there was a negative relationship between nest attentiveness and date of arrival to the study area in monogamous, but not in polygynous, males. We argue that sexual selection could not alone explain all sides of Northern Lapwing incubation, and suggest that individual differences in breeding quality may also be important. [source] Competition and Integration among Stock Exchanges in Europe: Network Effects, Implicit Mergers and Remote AccessEUROPEAN FINANCIAL MANAGEMENT, Issue 1 2001Carmine Di Noia The economic theory of network externalities and a simple-game theoretical framework are used to explore the issue of competition among stock exchanges and the possibility of consolidation in the European stock-exchange industry. The paper shows the existence of equilibria where exchanges may decide, even unilaterally, to achieve full compatibility through implicit mergers and remote access, specialising only in trading or listing services. Thus the consolidation of European exchanges into one may occur with a welfare-efficient outcome or with a lock-in to a Pareto-inferior equilibrium, due to the network externalities and the different starting points of the various exchanges. ,Implicit mergers' among exchanges together with remote access are always weakly (in half of the cases, strictly) more efficient than the actual competition. This finding also sheds light on the existence and efficacy, of ATS and rating agencies, which can be viewed respectfully as exchanges specialising in trading and listing services. [source] Effect of atorvastatin on microRNA 221,/,222 expression in endothelial progenitor cells obtained from patients with coronary artery diseaseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2009Y. Minami Abstract Background, Endothelial progenitor cells (EPCs) play an important role in the maintenance of vascular integrity. Lipid lowering therapy (LLT) with statins may contribute to biologically relevant activities including the proliferation of endothelial cells. The physiological role of microRNA (miR)-221/222, a newly discovered class of small RNA, is closely linked to the proliferation of endothelial cells. We therefore investigated whether LLT with statins might affect miR-221/222 expression in EPCs obtained from patients with coronary artery disease (CAD). Materials and methods, This study included 44 patients with stable CAD and 22 subjects without CAD (non-CAD). Patients with CAD were randomized to 12 months of LLT with atorvastatin (10 mg day,1) or pravastatin (10 mg day,1). EPCs were obtained from peripheral blood at baseline and after 12 months of statin therapy. Levels of miR-221/222 in EPCs were measured by real-time RT-PCR. Results, Levels of miR-221/222 were significantly higher in the CAD group than in the non-CAD group (P < 0·01). Levels of miR-221/222 were weakly negatively correlated with EPC number in the CAD group. After 12 months of therapy, changes in lipid profiles were greater in the atorvastatin group than in the pravastatin group. LLT with atorvastatin markedly increased EPC numbers and decreased miR-221/222 levels (all P < 0·05), whereas LLT with pravastatin did not change EPC numbers or miR-221/222 levels. Conclusions, This study demonstrates that LLT with atorvastatin increases EPC numbers and decreases miR-221/222 levels in patients with CAD, possibly contributing to the beneficial effects of LLT with atorvastatin in this disorder. [source] Comparative study on antibodies to human and bacterial 60 kDa heat shock proteins in a large cohort of patients with coronary heart disease and healthy subjectsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2001Z. Prohászka Background Recent observations indicate an association between antibodies against mycobacterial heat shock protein (hsp65) and coronary heart disease (CHD). Previously, we reported on marked differences in antigen specificity and complement activating ability of anti-hsp65 antibodies and auto-antibodies against human heat shock protein, hsp60. Here, we investigated whether there are differences between antih-sp65 and anti-hsp60 antibodies in their association with CHD. Design We measured by ELISA the levels of antibodies to hsp65, hsp60 and E. coli -derived GroEL in three groups: Group I, 357 patients with severe CHD who underwent by-pass surgery; Group II, 67 patients with negative coronary angiography; Group III, 321 healthy blood donors. Antibodies against Helicobacter pylori were also measured by commercial ELISA. Results As calculated by multiple regression analysis, the levels of anti-hsp60 auto-antibodies were significantly higher in Group I compared to Group II (P = 0·007) or Group III (P < 0·0001). By contrast, although concentrations of anti-hsp65 and anti-GroEL antibodies in Group I were higher than in Group III, no significant differences between Group I and Group II were found. Antibodies to the two bacterial hsp strongly correlated to each other, but either did not correlate or weakly correlated to hsp60. In Group I, serum concentrations of anti- H.pylori antibodies significantly correlated with those of anti-hsp65 and anti-GroEL antibodies but they did not correlate with the anti-hsp60 antibodies. Conclusion As to their clinical relevance, a remarkable difference become evident between antibodies to human hsp60 and antibodies against bacterial hsp in the extent of association with CHD. On the basis of these findings and some pertinent literature data, an alternative explanation for the association between high level of anti-hsp antibodies and atherosclerotic vascular diseases is raised. [source] A metabolic syndrome of hypertension, hyperinsulinaemia and hypercholesterolaemia in the New Zealand obese mouseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2000Ortlepp Background New Zealand obese (NZO) mice exhibit a polygenic obesity associated with hyperinsulinaemia and hyperglycaemia. Here we show that the strain presents additional features of a metabolic syndrome, i.e. elevated blood pressure, serum cholesterol and serum triglyceride levels. Materials and methods A back-cross model of NZO mice with the lean Swiss Jackson Laboratory (SJL) strain was established in order to investigate further the correlation between hypertension, obesity, serum insulin and hyperglycaemia. Results Systolic blood pressure was significantly elevated at 6 weeks of age and appeared to parallel the weight gain of the animals. Serum insulin levels, presumably reflecting insulin resistance, and systolic blood pressure values were significantly correlated with the body mass index (r2 = 0.707 and 0.486, respectively) in the back-cross mice. In contrast, blood pressure was only weakly correlated with serum insulin (r2 = 0.288) in non-diabetic mice, and was independent of serum insulin levels in diabetic animals. Conclusion The data are consistent with the concept that hypertension and insulin resistance are a characteristic consequence of the genetic constellation leading to obesity in the NZO strain, and that these traits reflect related mechanisms. It appears unlikely, however, that hypertension is a direct consequence of hyperinsulinaemia. [source] Recombinase-deficient T cell development by selective accumulation of CD3 into lipid raftsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2008Denise Ferrera Abstract The pre-T cell receptor (pre-TCR) promotes the development of thymocytes with productive rearrangement at the TCR ,,chain locus by signaling in a ligand-independent fashion. The TCR ,,chain associates with the invariant pre-T, (pT,) chain, which bears specific charged residues in the extracellular portion mediating pre-TCR self-oligomerization. In recombinase-deficient thymocytes, calnexin (CNX) associated with CD3 chains is inefficiently retained in the endoplasmic reticulum (ER) and weakly expressed in the plasma membrane. Deliberate cross-linking of CNX/CD3 complexes mimics pre-TCR signaling. Here, we show that, analogously to the pT, chain, surface CNX is palmitoylated and that CD3 prominently accumulated in lipid rafts upon cross-linking. Mutant CNX isoforms devoid of ER retention determined pre-TCR-like signaling and simulated ,,selection only when stably translocating CD3 to lipid rafts. Inclusion of the palmitoylated cytoplasmic tail from the pT, chain in recombinant CNX strikingly improved the pre-TCR-like signaling efficiency of CNX/CD3 in rafts. This study indicates that lipid rafts in the plasma membrane represent proficient microdomains for the initiation of pre-TCR signaling, and supports the view that ,,selection by oligomerized pre-TCR is implemented by the pT, cytoplasmic tail. [source] Toward an Allosteric Metallated ContainerEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2009Helga Szelke Abstract Polytopic ligands L1 and L2 in which three 2,2,-bipyridine units are linked to a central tris(pyrid-2-yl)amine (L1) or tris(pyrid-2-yl)methanol (L2) moiety by alkyl spacers were prepared by multistep organic syntheses. The parent tris(pyrid-2-yl)-type ligands were shown to be modest-to-good chelators for Zn2+ and Cu2+ ions in solution, and bi- and tridentate N-coordination was confirmed by crystal structures of CuII and RuII complexes, respectively. FeII and RuII smoothly form stable, cage-like 1:1 complexes with L1 and L2, in which the metal ion is coordinated to the tris(bpy) site of the ligands. The vacant tris(pyrid-2-yl) site of these complexes is, however, a poor donor site for Zn2+ and Cu2+ ions. In addition, FeII modulates the coordination behaviour of the tris(pyrid-2-yl) site toward Zn2+: Whereas tris(5-methylpyrid-2-yl)amine forms a 2:1 complex with Zn2+ in CH2Cl2, [Fe(L1)]2+ forms a 1:1 Zn complex. Spectrophotometric titrations suggest that [Fe(L2)]2+ forms a polynuclear Zn2+ complex in CH2Cl2, possibly involving bridging coordination of the alcohol OH group, which contrasts the smooth formation of a 2:1 complex of the parent tris(pyrid-2-yl)-type ligand with Zn. FeII might therefore be considered as an allosteric effector, which modulates the metal binding properties of the second tris(pyrid-2-yl) site of L1 and L2. Contrary to expectation, Zn2+ and Cu2+ appear to associate weakly with donor atoms directed toward the exterior of the cage-like complexes [Fe(Ln)]2+ and [Ru(L1)]2+, rather than locating in the interior of the container by tripodal coordination to the tris(pyrid-2-yl) site.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Hybrid Magnetic Materials Based on Nitroxide Free Radicals and Extended Oxalato-Bridged Bimetallic NetworksEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2005Antonio Alberola Abstract A series of hybrid organic-inorganic magnets of formula p -rad[MIICr(ox)3] [M = Mn (1), Co (2), Ni (3), Zn (4)] and m -rad[MIICr(ox)3] [M = Mn (5), Co (6)], in which N -methylpyridinium cations bearing a nitronyl nitroxide moiety in positions 3 (m -rad) or 4 (p -rad) of the pyridine ring coexist with the 2D honeycomb-like oxalato-bridged bimetallic lattice, has been prepared and studied by AC and DC magnetic susceptibility measurements and EPR spectroscopy. In general, the physical properties of these magnets are not altered significantly by the insertion of the nitronyl nitroxide radicals although these paramagnetic molecules seem to interact weakly with the inorganic network as demonstrated by EPR spectroscopy. Some differences can also be observed between the p -rad and m -rad series, i.e. m -rad derivatives have smaller values for the critical temperatures and coercive fields. We also report on the X-ray crystal structures and magnetic properties of p -rad[Mn(H2O)Cr(ox)3]·2H2O (7) and m -rad[Mn(H2O)2Cr(ox)3]·2H2O (8), two extended oxalato-bridged compounds with new topologies. Compound 7 is antiferromagnetic and its structure is a 3D achiral lattice in which zigzag ferromagnetic MnCr chains (J/k = +0.8 K) are interconnected to form hellicoidal hexagonal channels with the cationic free radicals residing in the free space. Compound 8, however, exhibits a ladder-like structural pattern with competing magnetic interactions and paramagnetic behaviour down to low temperatures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Assessment of idiopathic normal pressure patients in neurological practice: the role of lumbar infusion testing for referral of patients to neurosurgeryEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2008A. Brean Background and purpose:, In neurological practice patients with tentative idiopathic normal pressure hydrocephalus (iNPH) usually are referred to neurosurgery based on clinical and radiological findings. Hydrodynamic assessment using lumbar infusion testing might be helpful in selecting patients. To retrospectively analyse lumbar infusion tests done in neurological practice in iNPH patients to see how infusion test results relate to the clinical course and shunt response. Materials and methods:, Sixty-three consecutive patients with Possible/Probable iNPH were tested during a 1-year period. The pre-operative lumbar infusion tests were assessed according to two strategies: (i) Determining the resistance to cerebrospinal fluid (CSF) outflow (Rout). (ii) Quantification of the CSF pressure (CSFP) pulsatility during lumbar infusion (Qpulse). The results were related to the prospectively followed clinical course and shunt response after 12 months. Results:, The lumbar infusion-derived parameters Rout and Qpulse related weakly. Shunt response after 12 months was not related to Rout, but was highly related to the Qpulse. False negative results of lumbar infusion testing were observed in 16% of the patients. Discussion:, In neurological practice lumbar infusion testing may be useful for determining which patients to refer to neurosurgery. Our data favour determination of CSFP pulsatility (Qpulse) rather than Rout for prediction of shunt response. [source] Modulatory action of acetylcholine on striatal neurons: microiontophoretic study in awake, unrestrained ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003François Windels Abstract Cholinergic interneurons innervate virtually all medium spiny striatal cells, but the relevance of this input in regulating the activity and afferent responsiveness of these cells remains unclear. Studies in anaesthetized animals and slice preparations have shown that iontophoretic acetylcholine (ACh) either weakly excites or inhibits striatal neurons. These differential responses may reflect cholinergic receptor heterogeneity but may be also related to the different activity states of recorded units and different afferent inputs specific in each preparation. Single-unit recording was combined with iontophoresis in awake, unrestrained rats to examine the effects of ACh and selective muscarinic (oxotremorine M or Oxo-M) and nicotinic agonists (nicotine or NIC) on dorsal and ventral striatal neurons. These effects were tested on naturally silent, spontaneously active and glutamate-stimulated units. We found that iontophoretic ACh primarily inhibited spontaneously active and glutamate-stimulated units; the direction of the ACh response, however, was dependent on the firing rate. The effects of ACh were generally mimicked by Oxo-M and, surprisingly, by NIC, which is known to excite units in most central structures, including striatal neurons in anaesthetized preparation. Given that NIC receptors are absent on striatal cells but located primarily on dopamine terminals, we assessed the effects of NIC after complete blockade of dopamine receptors induced by systemic administration of a mixture of D1 and D2 antagonists. During dopamine receptor blockade the number of NIC-induced inhibitions dramatically decreased and NIC had mainly excitatory effects on striatal neurons. Thus, our data suggest that under physiologically relevant conditions ACh acts as a state-dependent neuromodulator, and its action involves not only postsynaptic but also presynaptic cholinoreceptors located on dopamine- and glutamate-containing terminals. [source] Right wing authoritarianism, social dominance orientation and the dimensions of generalized prejudiceEUROPEAN JOURNAL OF PERSONALITY, Issue 2 2007John Duckitt Abstract Prior research suggests that individuals' prejudiced attitudes form a single generalized dimension predicted by Right Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO). A dual process approach, however, expects different domains of generalized prejudice that relate differentially to RWA and SDO. To test this, 212 participants rated attitudes to 24 typically disliked groups. Factor analysis revealed three distinct generalized prejudice dimensions. Hierarchical Linear Modelling indicated that attitudes towards a ,dangerous' groups domain was significantly related only with RWA, attitudes toward a second ,derogated' groups domain was related only to SDO, and attitudes toward a third, ,dissident' groups, domain was significantly related to both, but powerfully with RWA and weakly with SDO. These findings have implications for explaining and reducing prejudice. Copyright © 2006 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||