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Clear Evidence (clear + evidence)
Kinds of Clear Evidence Selected AbstractsInteractions between metabolism of trace metals and xenobiotic agonists of the aryl hydrocarbon receptor in the antarctic fish Trematomus bernacchii: Environmental perspectivesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2005Francesco Regoli Abstract Although Antarctica is a pristine environment, organisms are challenged with contaminants either released locally or transported from industrialized regions through atmospheric circulation and marine food webs. Organisms from Terra Nova Bay also are exposed to a natural enrichment of cadmium, but to our knowledge, whether such environmental conditions influence biological responses to anthropogenic pollutants has never been considered. In the present study, the Antarctic rock cod (Trematomus bernacchii) was exposed to model chemicals, including polycyclic aromatic hydrocarbons (benzo[a]pyrene), persistent organic pollutants (2,3,7,8-tetrachlorodibenzo- p -dioxin [TCDD]), cadmium, and a combination of cadmium and TCDD. Analyzed parameters included chemical bioaccumulation, activity, and levels of biotransformation enzymes (cytochrome P4501A); metallothioneins and the efficiency of the antioxidant system measured as individual defenses (catalase, glutathione, glutathione reductase, glutathione S -transferases, and glutathione peroxidases); and total scavenging capacity toward peroxyl and hydroxyl radicals. Reciprocal interactions between metabolism of inorganic and organic pollutants were demonstrated. Dioxin enhanced the accumulation of cadmium, probably stored within proliferating endoplasmic reticulum, and cadmium suppressed the inducibility of cytochrome P4501A, allowing us to hypothesize a posttranscriptional mechanism as the depletion of heme group availability. Clear evidence of oxidative perturbation was provided by the inhibition of antioxidants and enhanced sensitivity to oxyradical toxicity in fish exposed to organic chemicals. Exposure to cadmium revealed counteracting responses of glutathione metabolism; however, these responses did not prevent a certain loss of antioxidant capacity toward peroxyl radicals. The pattern of antioxidant responses exhibited by fish coexposed to cadmium and TCDD was more similar to that observed for cadmium than to that observed for TCDD. The overall results suggest that elevated natural levels of cadmium in Antarctic organisms from Terra Nova Bay can limit biotransformation capability of polycyclic (halogenated) hydrocarbons, thus influencing the bioaccumulation and biological effects of these chemicals in key sentinel species. [source] Phase Segregation in Thin Films of Conjugated Polyrotaxane, Poly(ethylene oxide) Blends: A Scanning Force Microscopy Study,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007L. Sardone Abstract Scanning force microscopy (SFM) is used to study the surface morphology of spin-coated thin films of the ion-transport polymer poly(ethylene oxide) (PEO) blended with either cyclodextrin (CD)-threaded conjugated polyrotaxanes based on poly(4,4,-diphenylene-vinylene) (PDV), ,-CD,PDV, or their uninsulated PDV analogues. Both the polyrotaxanes and their blends with PEO are of interest as active materials in light-emitting devices. The SFM analysis of the blended films supported on mica and on indium tin oxide (ITO) reveals in both cases a morphology that reflects the substrate topography on the (sub-)micrometer scale and is characterized by an absence of the surface structure that is usually associated with phase segregation. This observation confirms a good miscibility of the two hydrophilic components, when deposited by using spin-coating, as suggested by the luminescence data on devices and thin films. Clear evidence of phase segregation is instead found when blending PEO with a new organic-soluble conjugated polymer such as a silylated poly(fluorene)- alt -poly(para -phenylene) based polyrotaxane (THS,,-CD,PF,PPP). The results obtained are relevant to the understanding of the factors influencing the interfacial and the intermolecular interactions with a view to optimizing the performance of light-emitting diodes, and light-emitting electrochemical cells based on supramolecularly engineered organic polymers. [source] Corticosteroids for acute chest syndrome in children with sickle cell disease: Variation in use and association with length of stay and readmission,AMERICAN JOURNAL OF HEMATOLOGY, Issue 1 2010Amy Sobota Acute chest syndrome (ACS) causes significant morbidity and mortality in sickle cell disease. The role of corticosteroids is unclear. The objectives of our study were to examine the variation between hospitals in their use of corticosteroids for ACS, describe characteristics associated with corticosteroids, and investigate the association between corticosteroids, length of stay, and readmission. We performed a retrospective examination of 5,247 hospitalizations for ACS between January 1, 2004, and June 30, 2008, at 32 hospitals in the Pediatric Health Information System database. We used multivariate regression to examine the variability in the use of corticosteroids adjusting for hospital case mix, identify factors associated with corticosteroid use, and evaluate the association of corticosteroids with length of stay and 3-day readmission rates controlling for propensity score. Corticosteroid use varied greatly by hospital (10,86% among all patients, 18,92% in patients with asthma). Treatment with corticosteroids was associated with comorbid asthma (OR 3.9, 95% CI: 3.2,4.8), inhaled steroids (OR 1.4, 95% CI: 1.1,1.7), bronchodilators (OR 3.2, 95% CI: 2.5,4.2), nitric oxide (OR 2.4, 95% CI: 1.2,5.0), oxygen (OR 2.3, 95% CI: 1.8,2.9), ICU (OR 1.7, 95% CI: 1.3,2.3), ventilation (OR 2.0, 95% CI: 1.4,2.8), APR-DRG severity level (OR 1.4, 95% CI: 1.2,1.6), and discharge year (OR 0.86, 95% CI: 0.80,0.92). Corticosteroids were associated with an increased length of stay (25%, 95% CI: 14,38%) and a higher 3-day readmission rate (OR 2.3, 95% CI: 1.6,3.4), adjusted for confounding. Hospitals vary greatly in the use of corticosteroids for ACS, even in patients with asthma. Clear evidence of the efficacy and toxicity of corticosteroid treatment in ACS may reduce variation in care. Am. J. Hematol. 2010. © 2009 Wiley-Liss, Inc. [source] Developmental changes in glutathione S -transferase activity in herbicide-resistant populations of Alopecurus myosuroides Huds (black-grass) in the fieldPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2001Lucy J Milner Abstract Herbicide-resistant populations of Alopecurus myosuroides Huds (black-grass) have become widespread throughout the UK since the early 1980s. Clear evidence suggests that more than one resistance mechanism exists, and glutathione S -transferases (GSTs) have been implicated in resistance due to enhanced metabolism. This study reports the determination of GST activity in four UK black-grass populations from field sites situated in the East Midlands. Data demonstrate that, as untreated plants in the field mature, there is an accompanying natural elevation of GST activity with natural environmental changes from winter to spring. We speculate that this endogenous change in enzyme activity with plant development in the field contributes to reduced efficacy of some graminicides applied in the spring. These observations are discussed in relation to predicting herbicide efficacy to achieve maximum control of this important grass weed. © 2001 Society of Chemical Industry [source] Are Friendly Acquisitions Too Bad for Shareholders and Managers?BRITISH JOURNAL OF MANAGEMENT, Issue S1 2006Friendly Acquirers, Long-Term Value Creation, Top Management Turnover in Hostile The well-documented failure of the majority of acquisitions to create value is often identified in popular discussion with hostile acquisitions, whereas friendly acquirers seem to get a friendly press. The relative performance of friendly and hostile acquirers therefore warrants a rigorous empirical investigation. Clear evidence of superior value creation in hostile over friendly acquisitions allows us to judge the efficacy of the market for corporate control. In this article we examine the long-term shareholder wealth performance of four types of acquirers , friendly bidder, hostile bidder, white knight and hostile bidder facing a white knight or another hostile bidder. For a sample of 519 acquisitions of UK target firms during 1983,1995, we estimated the three-year post-acquisition gains to acquirer shareholders and found that hostile acquirers deliver significantly higher shareholder value than friendly acquirers. We found that friendly acquirers with high stock-market ratings destroyed more value than hostile acquirers with a similar rating. Friendly acquirer top managers suffered greater job losses than those of hostile acquirers, perhaps paying the price for their inferior value-creation performance. Our study provides evidence of the superior value-creation performance of hostile acquirers and makes the case against takeover regulatory rules that may impede hostile takeovers. [source] Palladium-Catalyzed Cyclopropanation of Alkenyl Silanes by Diazoalkanes: Evidence for a Pd0 MechanismCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2009Guillaume Berthon-Gelloz Dr. Abstract Pd0does the trick! Alkenyl silanes are efficiently cyclopropanated by diazoalkanes at low Pd loadings (see scheme). Clear evidence for the involvement of a Pd0 resting state for this reaction is given. Alkenyl silanes are efficiently converted to the corresponding silyl cyclopropanes in the presence of a slight excess of diazomethane (2,4,equiv) and a low loading of Pd(OAc)2 (<0.5,mol,%). Diazoethane and diazobutane can also be employed and yield silyl cyclopropanes with diastereoselectivities of up to 10:1 for the trans isomer. When conducted on a 4,g scale, the reaction only required a catalyst loading of 5×10,3,mol,%, which corresponds to a turnover frequency of 40,000,h,1. Competition experiments revealed that vinyl silanes can be selectively cyclopropanated in the presence of an aliphatic terminal alkene and styrene. The complex [Pd02(DVTMS)3] (38, DVTMS=divinyltetramethyldisiloxane) proved to be an exceptionally active catalyst for the cyclopropanation reaction, giving complete conversion at ,35,°C in 1,min. Intermolecular and intramolecular competition experiments with DVTMS (36), both with Pd(OAc)2 and 38, provided strong evidence for a Pd0(alkenyl silane)3 resting state. Detailed density functional calculations on the reaction pathways for the cyclopropanation of trimethylvinylsilane and DVTMS by diazomethane with Pd0 corroborated the experimental observations. [source] HYBRID ACE: COMBINING SEARCH DIRECTIONS FOR HEURISTIC PLANNINGCOMPUTATIONAL INTELLIGENCE, Issue 3 2005Dimitris Vrakas One of the most promising trends in Domain-Independent AI Planning, nowadays, is state-space heuristic planning. The planners of this category construct general but efficient heuristic functions, which are used as a guide to traverse the state space either in a forward or in a backward direction. Although specific problems may favor one or the other direction, there is no clear evidence why any of them should be generally preferred. This paper presents Hybrid-AcE, a domain-independent planning system that combines search in both directions utilizing a complex criterion that monitors the progress of the search, to switch between them. Hybrid AcE embodies two powerful domain-independent heuristic functions extending one of the AcE planning systems. Moreover, the system is equipped with a fact-ordering technique and two methods for problem simplification that limit the search space and guide the algorithm to the most promising states. The bi-directional system has been tested on a variety of problems adopted from the AIPS planning competitions with quite promising results. [source] Ethics Seminars: Withdrawal of Treatment in the Emergency Department,When and How?ACADEMIC EMERGENCY MEDICINE, Issue 12 2006Kelly Bookman MD Abstract Although increasing discussion has occurred within emergency medicine about indications for withholding cardiac life support and other resuscitative interventions, emergency physicians (EPs) may be less familiar with the ethical, legal, and practical issues surrounding withdrawal of life support that has already been initiated. Both physicians and out-of-hospital personnel must act rapidly in critical situations and must assume that the patient has the desire to be resuscitated, unless clear evidence exists to the contrary. Often, only after initial life-saving actions have stabilized the patient is there time to reflect and determine a patient's desires regarding such interventions. When the EP can clearly discern a patient's previously stated wishes during the emergency department (ED) stay, these wishes should be honored in the ED. Respecting a patient's request to avoid unwanted, invasive treatments near death may involve withdrawing interventions that could not be withheld during the first few minutes of care. In this article, the authors use a case of out-of-hospital stabilization of a patient as a springboard to review the ethical and legal framework for withdrawal of life-sustaining care, as well as the practical issues involved with withdrawal of such care in the ED. [source] Cardiac anxiety in people with and without coronary atherosclerosis,DEPRESSION AND ANXIETY, Issue 10 2008Craig D. Marker Ph.D. Abstract Many studies have shown that cardiac anxiety when occurring in the absence of coronary artery disease is common and quite costly. The Cardiac Anxiety Questionnaire (CAQ) is an 18-item self-report measure that assesses anxiety related to cardiac symptoms. To better understand the construct of cardiac anxiety, a factor analysis was conducted on CAQ data from 658 individuals who were self or physician-referred for electron beam tomographic screening to determine whether clinically significant coronary atherosclerosis was present. A four-factor solution was judged to provide the best fit with the results reflecting the following factor composition: heart-focused attention, avoidance of activities that bring on symptoms, worry or fear regarding symptoms, and reassurance-seeking. Factorial invariance across groups was also assessed to determine whether the factor structure of the CAQ was similar in individuals with and without clear evidence of coronary atherosclerosis. The factor structure of the CAQ did not differ between the two groups. However, the group without coronary atherosclerosis had significantly higher mean scores on their attention and worry/fear factors suggesting that people without a diagnosed cardiac condition pay more attention to and worry more about their cardiac-related symptoms than those people who have coronary atherosclerosis. Depression and Anxiety 2007. Published 2007 Wiley-Liss, Inc. [source] Simple Transfers, Complex Outcomes: The Impacts of Pensions on Poor Households in BrazilDEVELOPMENT AND CHANGE, Issue 5 2006Peter Lloyd-Sherlock ABSTRACT Drawing on quantitative survey data and in-depth interviews, this article seeks to map out the potential direct and indirect effects of simple cash transfers on households in impoverished rural and urban settings. Brazil is shown to have an extensive system of old age pensions, which affords almost universal coverage to households containing older people. These benefits have a significant impact on levels of poverty and vulnerability in recipient households. They also facilitate access to essential healthcare items, such as drugs, which are seldom freely available through the state health system. The in-depth interviews reveal that pensions can have important effects on intra-household relations, but these effects were not generalizable nor easily captured by quantitative survey tools. There was clear evidence that pensions reduced the propensity of older people to remain economically active, but this must be understood in a context of limited employment opportunities for all age groups and a high prevalence of disability. Overall, the article demonstrates the complex effects of a relatively simple cash transfer, which policy makers need to take into account. [source] A review of studies describing the use of acetyl cholinesterase inhibitors in Parkinson's disease dementiaACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2005I. D. Maidment Objective:, To review the literature relating to the use of acetyl cholinesterase inhibitors in Parkinson's disease dementia (PDD). Method:, MEDLINE (1966 , December 2004), PsychINFO (1972 , December 2004), EMBASE (1980 , December 2004), CINHAL (1982 , December 2004), and the Cochrane Collaboration were searched in December 2004. Results:, Three controlled trials and seven open studies were identified. Efficacy was assessed in three key domains: cognitive, neuropsychiatric and parkinsonian symptoms. Conclusion:, Cholinesterase inhibitors have a moderate effect against cognitive symptoms. There is no clear evidence of a noticeable clinical effect against neuropsychiatric symptoms. Tolerability including exacerbation of motor symptoms , in particular tremor , may limit the utility of cholinesterase inhibitors. [source] Satellite sleuthing: does remotely sensed land-cover change signal ecological degradation in a protected area?DIVERSITY AND DISTRIBUTIONS, Issue 2 2009T. A. Waite ABSTRACT Aim, We evaluate whether remotely sensed land-cover change within a newly protected area signalled human-driven ecological degradation. Vegetation density changed in a quarter of pixels during the first 13 years (1986,1999) following the sanctuary's formal enclosure, with many patches showing a decrease in density. We use on-the-ground data collected in 2006 in 132 random plots to explore whether these changes in vegetation density reliably signalled latent shifts in local diversity of woody plants and whether they could be attributed to illicit activities including fuel wood collection and livestock grazing. Location, Kumbhalgarh Wildlife Sanctuary, Rajasthan, India. Results, Species richness, species sharing, species assemblages, and incidence of invasive and useful species were statistically similar among plots in which vegetation density had decreased, increased or remained similar. Likewise, intensity of disturbance associated with human activities was similar across these plot types. Main conclusions, Our data provide no clear evidence that local changes in vegetation density signalled latent shifts in local diversity of woody plants. They also fail to reveal any clear association between local changes in vegetation density and human-related activities. Finding no evidence that land-cover change led to biotic erosion, we reflect on the utility of resource-use bans in protected areas, particularly those embedded within historically coupled human-nature systems. [source] Warnings on alcohol containers and advertisements: International experience and evidence on effectsDRUG AND ALCOHOL REVIEW, Issue 4 2009CLAIRE WILKINSON Abstract Issues. In light of possible introduction of alcohol warning labels in Australia and New Zealand, this paper discusses the international experience with and evidence of effects of alcohol warning labels. Approach. The report describes international experience with providing information and warnings concerning the promotion or sale of alcoholic beverages, and considers the evidence on the effects of such information and warnings. The experience with and evaluations of the effects of tobacco warning labels are also considered. Key Findings. The most methodologically sound evaluations of alcohol warning labels are based on the US experience. Although these evaluations find little evidence that the introduction of the warning label in the USA had an impact on drinking behaviour, there is evidence that they led to an increase in awareness of the message they contained. In contrast, evaluations of tobacco warning labels find clear evidence of effects on behaviour. Implications. There is a need and opportunity for a rigorous evaluation of the impacts of introducing alcohol warning labels to add to the published work on their effectiveness. The experience with tobacco labels might guide the way for more effective alcohol warning labels. Conclusion. Alcohol warning labels are an increasingly popular alcohol policy initiative. It is clear that warning labels can be ineffective, but the tobacco experience suggests that effective warning labels are possible. Any introduction of alcohol warning labels should be evaluated in terms of effects on attitudes and behaviour.[Wilkinson C, Room R. Warnings on alcohol containers and advertisements: International experience and evidence on effects. Drug Alcohol Rev 2009;28:426,435] [source] Peer overdose resuscitation: multiple intervention strategies and time to response by drug users who witness overdoseDRUG AND ALCOHOL REVIEW, Issue 3 2002DAVID BEST Abstract One hundred and thirty-five drug users in contact with treatment services in Scotland and England were interviewed about their experiences of witnessing overdoses both overdoses resolved successfully and those leading to death and actions taken to effect resuscitation. One hundred and four (77%) had witnessed a mean of 11.5 overdoses, of whom 41 (30.4% of the study sample) had witnessed an average of 4.2 fatal overdoses. A wide range of actions was reported at the most recent witnessed overdose, the most common being slapping or shaking the victim (an average of 2.5 minutes after overdose was first recognised) or walking the person around the room (3.2 minutes after recognizing overdose). There was no consistent relationship between the time taken to acting and the number of actions taken. Successful resolution of last witnessed overdose was associated more strongly with immediate onset of overdose, while those that led to death were more often those that involved slow onset of overdose. There is clear evidence of the opportunity and willingness of witnesses to intervene, particularly when overdose onset is immediate, with a wide range of strategies adopted to encourage recovery, although these may often be inappropriate and wrongly prioritized. [source] Procedural learning and dyslexiaDYSLEXIA, Issue 3 2010R. I. Nicolson Abstract Three major ,neural systems', specialized for different types of information processing, are the sensory, declarative, and procedural systems. It has been proposed (Trends Neurosci.,30(4), 135,141) that dyslexia may be attributable to impaired function in the procedural system together with intact declarative function. We provide a brief overview of the increasing evidence relating to the hypothesis, noting that the framework involves two main claims: first that ,neural systems' provides a productive level of description avoiding the underspecificity of cognitive descriptions and the overspecificity of brain structural accounts; and second that a distinctive feature of procedural learning is its extended time course, covering from minutes to months. In this article, we focus on the second claim. Three studies,speeded single word reading, long-term response learning, and overnight skill consolidation,are reviewed which together provide clear evidence of difficulties in procedural learning for individuals with dyslexia, even when the tasks are outside the literacy domain. The educational implications of the results are then discussed, and in particular the potential difficulties that impaired overnight procedural consolidation would entail. It is proposed that response to intervention could be better predicted if diagnostic tests on the different forms of learning were first undertaken. Copyright © 2010 John Wiley & Sons, Ltd. [source] Climatic adaptation in an isolated and genetically impoverished amphibian populationECOGRAPHY, Issue 4 2010Germán Orizaola The capacity of populations to respond adaptively to environmental change is essential for their persistence. Isolated populations often harbour reduced genetic variation, which is predicted to decrease adaptive potential, and can be detrimental under the current scenarios of global change. In this study, we examined climatic adaptation in larval life history traits in the pool frog Rana lessonae along a latitudinal gradient across the northern distribution area of the species, paying special attention to the isolated and genetically impoverished fringe populations in central Sweden. Larvae from eight populations within three geographic areas (Poland, Latvia and Sweden) were reared under three temperatures (19, 22 and 26°C) in a common garden laboratory experiment. We found clear evidence for latitudinal adaptation in R. lessonae populations, larvae from higher latitudes growing and developing faster than low-latitude ones. Larvae from the Swedish populations were able to compensate for the effects of cooler temperatures and a shorter growth season with genetically higher growth and development rates (i.e. countergradient variation) in the two higher temperature treatments, but there was no difference among the populations at the lowest temperature treatment, which is likely to be close to the temperature limiting growth in R. lessonae. Our results demonstrate that isolated and genetically impoverished populations can be locally adapted, and identify the Swedish fringe populations as a significant conservation unit adapted to the northern environmental conditions. [source] Ambient ultraviolet-B radiation reduces hatchling size in the common frog Rana temporariaECOGRAPHY, Issue 5 2000Maarit Pahkala Effects of ambient UV-B radiation and pH on hatchability and early development of Rana temporaria embryos were studied in field experiments conducted at two sites in Sweden. In neither of the populations did we find clear evidence for reduced hatchability or increased frequency of developmental anomalies of embryos exposed to ambient UV-B levels. However, in both populations hatchling size was significantly larger UV-B blocked as compared to control treatments, suggesting that ambient UV-B levels had a negative effect on early growth of embryos. This result is consistent with the hypothesis that the cellular UV-B damage repair mechanisms are costly and trades-off against early growth. Alternatively, UV-B induced photoproducts inhibiting DNA-transcription and thereby protein synthesis may directly reduce growth rate. Although low pH (5.0) had negative effects on hatchability and early embryonic growth, there was no evidence for synergistic effects of pH and UV-B on hatchability, frequency of developmental anomalies or early growth. The results suggest that increased levels of UV-B radiation may cause fitness loss in natural populations of the common frog. [source] Penguins as oceanographers unravel hidden mechanisms of marine productivityECOLOGY LETTERS, Issue 3 2002Jean-Benoît Charrassin ABSTRACT A recent concept for investigating marine ecosystems is to employ diving predators as cost-effective, autonomous samplers of environmental parameters (such as sea-temperature). Using king penguins during their foraging trips at sea, we obtained an unprecedented high resolution temperature map at depth off the Kerguelen Islands, Southern Ocean, a poorly sampled but productive area. We found clear evidence of a previously unknown subsurface tongue of cold water, flowing along the eastern shelf break. These new results provide a better understanding of regional water circulation and help explain the high primary productivity above the Kerguelen Plateau. [source] Biogeography of the marine actinomycete SalinisporaENVIRONMENTAL MICROBIOLOGY, Issue 11 2006Paul R. Jensen Summary Marine actinomycetes belonging to the genus Salinispora were cultured from marine sediments collected at six geographically distinct locations. Detailed phylogenetic analyses of both 16S rRNA and gyrB gene sequences reveal that this genus is comprised of three distinct but closely related clades corresponding to the species Salinispora tropica, Salinispora arenicola and a third species for which the name ,Salinispora pacifica' is proposed. Salinispora arenicola was cultured from all locations sampled and provides clear evidence for the cosmopolitan distribution of an individual bacterial species. The co-occurrence of S. arenicola with S. tropica and S. pacifica suggests that ecological differentiation as opposed to geographical isolation is driving speciation within the genus. All Salinispora strains cultured to date share greater than 99% 16S rRNA gene sequence identity and thus comprise what has been described as a microdiverse ribotype cluster. The description of this cluster as a new genus, containing multiple species, provides clear evidence that fine-scale 16S rDNA sequence analysis can be used to delineate among closely related species and that more conservative operational taxonomic unit values may significantly underestimate global species diversity. [source] Role of ethylenediaminetetraacetic acid on lead uptake and translocation by tumbleweed (Salsola kali L.)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007Guadalupe de la Rosa Abstract Tumbleweed plants (Salsola kali L.) grown in agar and liquid media demonstrated a high capacity to accumulate Pb in their different parts without affecting biomass. Whereas shoot elongation and biomass were not significantly affected by high tissue concentrations of Pb, root growth was significantly affected relative to controls. Roots, stems, and leaves demonstrated Pb concentrations of 31,000, 5,500, and 2,100 mg/kg dry weight, respectively, when plants were grown in the agar medium containing 80 mg Pb/L. Application of ethylenediaminetetraacetic acid (EDTA) to Pb-contaminated media dramatically reduced the total acquisition of Pb from both types of media. However, EDTA significantly increased the translocation of Pb from roots to the aerial parts, as evidenced by a multifold increase (23- and 155-fold for agar and liquid media, respectively) in the translocation concentration factor. The concentration of the antioxidant thiol compounds significantly increased (p < 0.05) in plants grown with uncomplexed Pb treatments relative to control plants. Scanning-electron microscopy and electron dispersive x-ray spectroscopic evaluation of leaf samples demonstrated an interesting pattern of Pb translocation in the presence or absence of EDTA. Large Pb crystals were found across the leaf tissues (palisade, spongy parenchyma, and conducting tissues) in the absence of EDTA. Lead nanoparticles also were seen when plants were grown in Pb-EDTA solution. Ultramicroscopic features of tumbleweed provide clear evidence for the unrestricted conduction of Pb from the root to the aerial parts, and this property makes the plant a good candidate for phytoremediation. [source] Copper toxicity in relation to surface water-dissolved organic matter: Biological effects to Daphnia magnaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2004Kees J.M. Kramer Abstract Water quality standards for copper are usually stated in total element concentrations. It is known, however, that a major part of the copper can be bound in complexes that are biologically not available. Natural organic matter, such as humic and fulvic acids, are strong complexing agents that may affect the bioavailable copper (Cu2+) concentration. The aim of this study was to quantify the relation between the concentration of dissolved natural organic matter and free Cu2+ in surface waters, and the biological effect, as measured in a standardized ecotoxicological test (48 h-median effective concentration [EC50] Daphnia magna, mobility). Six typical Dutch surface waters and an artificial water, ranging from 0.1 to 22 mg/L dissolved organic carbon (DOC), were collected and analyzed quarterly. Chemical speciation modeling was used as supporting evidence to assess bioavailability. The results show clear evidence of a linear relation between the concentration of dissolved organic carbon (in milligrams DOC/L) and the ecotoxicological effect (as effect concentration, EC50, expressed as micrograms Cu/L): 48-h EC50 (Daphnia, mobility) = 17.2 × DOC + 30.2 (r2 = 0.80, n = 22). Except for a brook with atypical water quality characteristics, no differences were observed among water type or season. When ultraviolet (UV)-absorption (380 nm) was used to characterize the dissolved organic carbon, a linear correlation was found as well. The importance of the free copper concentration was demonstrated by speciation calculations: In humic-rich waters the free Cu2+ concentration was estimated at ,10,11 M, whereas in medium to low dissolved organic carbon waters the [Cu2+] was ,10,10 M. Speciation calculations performed for copper concentrations at the effective concentration level (where the biological effect is considered the same) resulted in very similar free copper concentrations (,10,8 M Cu) in these surface waters with different characteristics. These observations consistently show that the presence of organic matter decreases the bioavailability, uptake, and ecotoxicity of copper in the aquatic environment. It demonstrates that the DOC content must be included in site-specific environmental risk assessment for trace metals (at least for copper). It is the quantification of the effects described that allows policy makers to review the criteria for copper in surface waters. [source] Aphasic or amnesic status epilepticus detected on PET but not EEGEPILEPSIA, Issue 2 2009Christine Dong Summary Purpose:, To describe five patients with ictal aphasia and one patient with ictal amnesia, who had focal positron emission tomography (PET) hypermetabolism but no clear ictal activity on electroencephalography (EEG). Methods:,18F-Fluorodeoxyglucose (FDG),PET scans with concomitant EEG were obtained in five patients with suspected ictal aphasia or ictal amnesia without ictal activity on EEG. We reviewed medical history, EEG, imaging data, and treatment outcome. Results:, Brain magnetic resonance imaging (MRI) showed no structural abnormalities in any of the patients. EEG showed left temporal irregular delta activity in three patients, with aphasia and nonspecific abnormalities in two other patients, all without clear ictal pattern. All patients demonstrated focal hypermetabolism on PET scan. The hypermetabolism was in the left frontotemporal region in patients with ictal aphasia and in the bilateral hippocampal region in the patient with amnesia. Three patients who received intravenous benzodiazepines during their episodes had transient clinical improvement. With antiepileptic drug (AED) treatment, symptoms gradually resolved in all patients. Concomitant resolution of PET hypermetabolism was documented in three patients who had follow up scans. One patient with ictal aphasia later developed recurrent episodes, each with recurrent PET hypermetabolism. This patient and one other patient required immune-modulating therapy in addition to AEDs. Discussion:, FDG-PET imaging should be considered as a diagnostic tool in patients with suspected ictal aphasia or amnesia, who fail to show clear evidence of ictal activity on EEG. [source] Dual ETA/ETB vs. selective ETA endothelin receptor antagonism in patients with pulmonary hypertensionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2006C. F. Opitz Abstract Since the identification of endothelin as a key mediator in the pathogenesis of several diseases, including pulmonary arterial hypertension (PAH), the pharmacologic control of the activated endothelin system with endothelin receptor antagonists (ETRA) has been a major therapeutic achievement for the treatment of patients with PAH. To date, dual ETA/ETB and selective ETA receptor antagonists have clinically been evaluated. To answer the question of whether selective or dual ETRA is preferable in patients with PAH, experimental and clinical data with relevance to the pulmonary circulation are reviewed in this article. Whereas experimental and clinical data provide unambiguous evidence that ETA receptors mediate the detrimental effects of ET-1, such as vasoconstriction and cell proliferation, the elucidation of the role of ETB receptors has been more complex. It has been shown that there is a subpopulation of ETB receptors on smooth muscle cells and fibroblasts mediating vasoconstriction and proliferation. On the contrary, there is clear evidence that endothelial ETB receptors continue to mediate vasodilation, vasoprotection and ET-1 clearance despite the pathology associated with pulmonary hypertension. More difficult to assess is the net effect of these mechanisms in patients to be treated with ETRA. When considering the available data from controlled clinical trials, nonselectivity does not appear to carry a relevant clinical benefit for the treatment of patients with PAH when compared with selective ETA receptor antagonism. [source] The Transient Titanocene(II): Direct Synthesis from Solvated Titanium(II) Chloride and Cyclopentadienylsodium and Ensuing Interception with Diphenylacetylene as 1,1-Bis(cyclopentadienyl)-2,3,4,5-tetraphenyltitanacyclopentadiene,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2007John J. Eisch Abstract For the first time the unstable titanocene(II) has been directly synthesized by the Wilkinson metallocene approach, namely the interaction of a THF-soluble form of titanium(II) chloride with two equivalents of cyclopentadienylsodium in THF solution at 0°,25 °C. Because of the transient existence of the titanocene(II) thereby obtained, it could only be chemically trapped in high yield as 1,1-bis(cyclopentadienyl)-2,3,4,5-tetraphenyltitanacyclopentadiene by two equivalents of diphenylacetylene, if the acetylene was added at 25 °C, without removal of the by-product LiCl and NaCl. If the addition of the acetylene was delayed, in order to filter off the LiCl and NaCl from the reaction mixture, then no trace of the titanacyclopentadiene derivative was found upon hydrolytic workup. Instead, a significant portion of the acetylene was found to have undergone hydrotitanation. This finding is clear evidence that the titanocene(II) had undergone a precedented rearrangement to a known dimer having the structure of a titanocene(III) hydride with a fulvalene bridge between the titanium centers. We suggest that the LiCl and NaCl present in the unfiltered reaction mixture form a dichloro complex with titanocene(II) and thereby retard its dimerizing rearrangement to the titanocene(III) hydride. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Creatine has no beneficial effect on skeletal muscle energy metabolism in patients with single mitochondrial DNA deletions: a placebo-controlled, double-blind 31P-MRS crossover studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 4 2005C. Kornblum The purpose of our randomized, double-blind, placebo-controlled crossover study in 15 patients with chronic progressive external ophthalmoplegia (CPEO) or Kearns,Sayre syndrome (KSS) because of single large-scale mitochondrial (mt) DNA deletions was to determine whether oral creatine (Cr) monohydrate can improve skeletal muscle energy metabolism in vivo. Each treatment phase with Cr in a dosage of 150 mg/kg body weight/day or placebo lasted 6 weeks. The effect of Cr was estimated by phosphorus-31 magnetic resonance spectroscopy (31P-MRS), clinical and laboratory tests. 31P-MRS analysis prior to treatment showed clear evidence of severe mitochondrial dysfunction. However, there were no relevant changes in 31P-MRS parameters under Cr. In particular, phosphocreatine (PCr)/ATP at rest did not increase, and there was no facilitation of post-exercise PCr recovery. Clinical scores and laboratory tests did not alter significantly under Cr, which was tolerated without major side-effects in all patients. Cr supplementation did not improve skeletal muscle oxidative phosphorylation in our series of patients. However, one explanation for our negative findings may be the short study duration or the limited number of patients included. [source] Dream recall frequency and sleep quality of patients with restless legs syndromeEUROPEAN JOURNAL OF NEUROLOGY, Issue 2 2001M. Schredl The present study investigated the dream recall frequency and the pattern of influencing factors of patients with restless legs syndrome in comparison with healthy controls. The patients' dream recall frequency did not differ from that of healthy controls. Dream recall, however, was negatively associated with the number of periodic leg movements with arousal (PLMAI). Subjective estimates of sleep quality or feeling of being refreshed in the morning, on the other hand, did not correlate with the PLMAI index. Whereas subjective sleep parameters were related to dream recall frequency in healthy controls, no substantial relationships were found in the patient group, except for the positive correlation between sleep latency and dream recall frequency. The results of the present study can not be interpreted as clear evidence for the arousal,retrieval model of dream recall; it seems plausible that other factors, e.g. the functional state of the brain, are of importance in explaining dream recall in this patient group. [source] Extracellular signal-regulated kinase activation is required for consolidation and reconsolidation of memory at an early stage of ontogenesisEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2009Solčne Languille Abstract The ability to form long-term memories exists very early during ontogeny; however, the properties of early memory processes, brain structures involved and underlying cellular mechanisms are poorly defined. Here, we examine the role of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase/ERK signaling cascade, which is crucial for adult memory, in the consolidation and reconsolidation of an early memory using a conditioned taste aversion paradigm in 3-day-old rat pups. We show that intraperitoneal injection of SL327, the upstream mitogen-activated protein kinase kinase inhibitor, impairs both consolidation and reconsolidation of early memory, leaving short-term memory after acquisition and after reactivation intact. The amnesic effect of SL327 diminishes with increasing delays after acquisition and reactivation. Biochemical analyses revealed ERK hyperphosphorylation in the amygdala but not the hippocampus following acquisition, suggesting functional activation of the amygdala as early as post-natal day 3, although there was no clear evidence for amygdalar ERK activation after reactivation. These results indicate that, despite an immature brain, the basic properties of memory and at least some of the molecular mechanisms and brain structures implicated in aversion memory share a number of similarities with the adult and emerge very early during ontogeny. [source] Enzymes in the acquired enamel pellicleEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2005Christian Hannig The acquired pellicle is a biofilm, free of bacteria, covering oral hard and soft tissues. It is composed of mucins, glycoproteins and proteins, among which are several enzymes. This review summarizes the present state of research on enzymes and their functions in the dental pellicle. Theoretically, all enzymes present in the oral cavity could be incorporated into the pellicle, but apparently enzymes are adsorbed selectively onto dental surfaces. There is clear evidence that enzymes are structural elements of the pellicle. Thereby they exhibit antibacterial properties but also facilitate bacterial colonization of dental hard tissues. Moreover, the immobilized enzymes are involved in modification and in homeostasis of the salivary pellicle. It has been demonstrated that amylase, lysozyme, carbonic anhydrases, glucosyltransferases and fructosyltransferase are immobilized in an active conformation in the pellicle layer formed in vivo. Other enzymes, such as peroxidase or transglutaminase, have been investigated in experimental pellicles. Despite the depicted impact of enzymes on the formation and function of pellicle, broader knowledge on their properties in the in vivo -formed pellicle is required. This might be beneficial in the development of new preventive and diagnostic strategies. [source] Opinion-based group membership as a predictor of commitment to political actionEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 1 2007Ana-Maria Bliuc Research on group identification has shown it to be a surprisingly weak predictor of intentions to take large-scale social action. The weak links may exist because researchers have not always examined identification with the type of group that is most relevant for predicting action. Our focus in two studies (one in Romania and one in Australia, both Ns,=,101) was on opinion-based groups (i.e. groups formed around shared opinions). We found that social identification with opinion-based groups was an excellent predictor of political behavioural intentions, particularly when items measuring identity certainty were included. The results provide clear evidence of the role of social identity constructs for predicting commitment to social action and complement analyses of politicised collective identity and crowd behaviour. Copyright © 2006 John Wiley & Sons, Ltd. [source] INCREASED POSTCOPULATORY SEXUAL SELECTION REDUCES THE INTRAMALE VARIATION IN SPERM DESIGNEVOLUTION, Issue 6 2008Simone Immler Sperm competition is an important force driving the evolution of sperm design and function. Inter- and intraspecific variation in sperm design are strongly influenced by the risk of sperm competition in many taxa. In contrast, the variation among sperm of one male (intramale variation) is less well understood. We investigated intramale variation in sperm design in passerine birds and found that risk of sperm competition is negatively associated with intramale variation. This result is the first clear evidence that variation among sperm within an individual male is influenced by postcopulatory sexual selection. Our finding has important implications for male traits under pre- and postcopulatory sexual selection. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||