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Potential Concern (potential + concern)
Selected AbstractsEffects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of select crop species,,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2008Jaclyn E. Cañas Abstract Single-walled carbon nanotubes have many potential beneficial uses, with additional applications constantly being investigated. Their unique properties, however, create a potential concern regarding toxicity, not only in humans and animals but also in plants. To help develop protocols to determine the effects of nanotubes on plants, we conducted a pilot study on the effects of functionalized and nonfunctionalized single-walled carbon nanotubes on root elongation of six crop species (cabbage, carrot, cucumber, lettuce, onion, and tomato) routinely used in phytotoxicity testing. Nanotubes were functionalized with poly-3-aminoben-zenesulfonic acid. Root growth was measured at 0, 24, and 48 h following exposure. Scanning-electron microscopy was used to evaluate potential uptake of carbon nanotubes and to observe the interaction of nanotubes with the root surface. In general, nonfunctionalized carbon nanotubes affected root length more than functionalized nanotubes. Nonfunctionalized nanotubes inhibited root elongation in tomato and enhanced root elongation in onion and cucumber. Functionalized nanotubes inhibited root elongation in lettuce. Cabbage and carrots were not affected by either form of nanotubes. Effects observed following exposure to carbon nanotubes tended to be more pronounced at 24 h than at 48 h. Microscopy images showed the presence of nanotube sheets on the root surfaces, but no visible uptake of nanotubes was observed. [source] El Niño, climate change, and Southern African climateENVIRONMETRICS, Issue 4 2001Simon J. Mason Abstract The El Niño phenomenon involves a large-scale warming of the equatorial eastern and central Pacific Ocean. Recent developments in the El Niño,Southern Oscillation (ENSO) phenomenon have raised concerns about climate change. In this review paper, these recent developments are critically assessed and forecasts of possible future changes are reviewed. Since the late-1970s, El Niño episodes have been unusually recurrent, while the frequency of strong La Niña events has been low. Prolonged/recurrent warm event conditions of the first half of the 1990s were the result of the persistence of an anomalously warm pool near the date line, which, in turn, may be part of an abrupt warming trend in tropical sea-surface temperatures that occurred in the late-1970s. The abrupt warming of tropical sea-surface temperatures has been attributed to the enhanced-greenhouse effect, but may be indicative of inter-decadal variability: earlier changes in the frequency of ENSO events and earlier persistent El Niño and La Niña sequences have occurred. Most forecasts of ENSO variability in a doubled-CO2 climate suggest that the recent changes in the tropical Pacific are anomalous. Of potential concern, however, is a possible reduction in the predictability of ENSO events given a warmer background climate. El Niño events usually are associated with below-normal rainfall over much of southern Africa. Mechanisms for this influence on southern African climate are discussed, and the implications of possible changes in ENSO variability on the climate of the region are assessed. Recent observed changes in southern African climate and their possible relationships with trends in ENSO variability are investigated. The El Niño influence on rainfall over southern Africa occurs largely because of a weakening of tropical convection over the subcontinent. A warming of the Indian Ocean during El Niño events appears to be important in providing a teleconnection from the equatorial Pacific Ocean. The abrupt warming of the tropical Pacific and Indian oceans in the late-1970s is probably partly responsible for increasing air temperatures over southern Africa, and may have contributed to a prolongation of predominantly dry conditions. A return to a wet phase appears to have occurred, despite the persistence of anomalously high sea-surface temperatures associated with the late-1970s warming, and a record-breaking El Niño in 1997/98. Copyright © 2001 John Wiley & Sons, Ltd. [source] Injectable opiate maintenance in the UK: is it good clinical practice?ADDICTION, Issue 4 2001Deborah Zador This paper reviews the current practice of injectable opiate treatment (IOT) in the United Kingdom, i.e. the "British system" of prescribing injectable heroin and methadone, and considers some of the clinical and ethical issues it raises. There is very limited research evidence supporting either the safety or effectiveness of IOT as practised in Britain. In particular there is almost no evaluation of long-term outcomes of IOT, which is of potential concern given the possibility of some patients remaining indefinitely in IOT, the risk of vascular complications, and its higher cost compared with oral maintenance. It would be easy to assess this controversial intervention as in need of further research. However, striving towards best practice in IOT involves more than generating evidence. The likelihood of a patient receiving IOT in the United Kingdom appears to be influenced more by the personal inclinations of prescribers than by outcome data (if any), or identified community needs for access to IOT. The author asks is this good clinical practice and is it sustainable? The "British system" needs to modernise itself consistent with international paradigms of continuous quality improvement, and the NHS's own agenda of clinical governance. [source] Contemporary and historical impacts of megaherbivores on the population structure of tree euphorbias in South African subtropical thicketAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Richard M. Cowling Abstract African elephant and black rhinoceros , both megaherbivores , impact negatively on the abundance of succulent plants, including tree succulents, in South Africa's subtropical thicket. We sampled 35 sites in subtropical thicket to assess historical and contemporary impacts of African elephant and black rhinoceros on the population structure of three species of succulent tree euphorbia. Population age structures were highly variable and showed no species-specific effects. Almost half the sites had growing populations dominated by young individuals. Sites having contemporary impacts had significantly fewer individuals in the 30,75 years age range, but this effect declined with increasing terrain slope. Eighty-one percent of sites assumed to have been impacted by megaherbivores historically had individuals that predated rhino and elephant extirpation in the region. This and other population age structure data indicate that megaherbivores and tree euphorbias coexisted historically on terrain of low relief. However, in areas not subject to contemporary impacts, euphorbia populations are likely to be much higher now than historically, owing to population relaxation after the extirpation of megaherbivores in the mid 1800s. Given the sensitivity of tree euphorbias to megaherbivore impacts, managers should consider monitoring the population structure of these species in order to identify thresholds of potential concern regarding megaherbivore impacts. Résumé L'éléphant et le rhinocéros africains , deux méga-herbivores , ont un impact négatif sur l'abondance de plantes succulentes, y compris des arbres succulents, dans les fourrés subtropicaux d'Afrique du Sud. Nous avons prélevé des échantillons dans 35 fourrés subtropicaux afin d'évaluer les impacts anciens et actuels des éléphants et des rhinos noirs africains sur la structure de la population de trois espèces d'euphorbes arborescentes succulentes. Les structures d'âges des populations étaient très variables et ne présentaient aucun effet spécifique des espèces. Près de la moitié des sites contenaient des populations en croissance dominées par de jeunes individus. Les sites qui présentaient des impacts actuels comptaient significativement moins d'individus de la classe d'âge comprise entre 30 et 75 ans, mais cet effet diminuait lorsque la pente du terrain s'accentuait. Quatre-vingt-un pour cent des sites supposés avoir subi jadis l'impact des méga-herbivores contenaient des individus qui dataient d'avant l'élimination des rhinos et des éléphants. Ceci, tout comme d'autres données sur la structure d'âge des populations, indique que les méga-herbivores et les euphorbes arborescentes ont longtemps coexisté sur les terrains de faible relief. Cependant, dans les zones qui ne subissent aucun impact actuel, les populations d'euphorbes sont susceptibles d'être beaucoup plus hautes aujourd'hui que jadis, en raison de la libération induite par l'élimination des méga-herbivores au milieu des années 1800. Etant donné la sensibilité des euphorbes arborescentes face aux impacts des méga-herbivores, les gestionnaires devraient envisager le suivi continu de la structure de la population de ces espèces afin de déterminer les seuils d'alerte potentiels en ce qui concerne les impacts des méga-herbivores. [source] The use of ribotyping and antibiotic resistance patterns for identification of host sources of Escherichia coli strainsLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2005M. Samadpour Abstract Aims:, To compare antibiotic resistance and ribotyping patterns ability to identify triplicate isolates sent from a group of 40 Escherichia coli taken from seven host sources. Methods and Results:, Of the 120 isolates, 22 isolates were resistant to ampicillin, streptomycin, tetracycline and trimethoprim and 98 isolates were susceptible. Antibiotic patterns identified 33 of the triplicates and three of the six groups had isolates from multiple hosts. Ribotyping divided the isolates into 27 ribotype groups with all triplicates grouped into the same ribotype group with one host per group. Conclusions:, Antibiotic susceptibility pattern placed 98 of the isolates in a single group with 50% of the antibiotic susceptibility pattern groups containing multiple host species. Ribotyping groups were host specific with each host having one to seven ribotype groups. Significance and Impact of the Study:, Antibiotic susceptibility pattern groups have been used for environmental source identification and faecal pollution tracking, however these groups do not always distinguish between host species. Stability of the markers is a potential concern and this system can only be used if antibiotic resistance levels are high in the isolates studied. All isolates have a ribotype group which was stable and like other molecular methods has advantages over antibiotic susceptibility pattern groups which uses a phenotypic method. [source] Stages of activation of hepatic stellate cells: effects of ellagic acid, an inhibiter of liver fibrosis, on their differentiation in cultureCELL PROLIFERATION, Issue 6 2003G. H. BuniatianArticle first published online: 17 NOV 200 Sparse rat liver cell cultures were grown in media containing EA (3, 6, 30 and 100 µg/ml) and, as controls, without EA, and inspected until day 7 in culture. The cells were double-labelled with antibodies against glial fibrillary acidic protein (GFAP) and smooth muscle alpha-actin (SMAA), marker proteins of quiescent and activated HSC, respectively. In EA-free culture conditions, the quiescent (SMAA,/GFAP+) HSC transiently acquired a semi-activated (SMAA+/GFAP+), phenotype and were further transformed into activated (SMAA+/GFAP,), pleomorphic HSC. Up to a concentration of 30 µg/ml, EA induced an early synthesis of SMAA in all HSC and inhibited their morphologic differentiation and individual growth throughout the culture period. At a concentration of 6 µg/ml, EA supported the semi-activated (SMAA+/GFAP+) phenotype of HSC throughout the culture period, whereas treatment with high EA concentrations (30 µg/ml) resulted in an early loss of GFAP expression. In conclusion: (i) the uniform response of HSC to EA by mild activation adds functional significance to cellular features preceding the transformation of HSC to myofibroblasts; (ii) the high sensitivity of HSC to EA treatment suggests their involvement in any mechanisms of protection by this antioxidant; (iii) the maintenance of HSC morphology might be one of the factors playing a role in the prevention or slowing down of liver fibrosis; (iv) because the effects of EA are concentration- and time-dependent, an arbitrary usage of this antioxidant is a matter of potential concern; (v) the various patterns of HSC activation observed might correspond to distinct activities of these cells, which, in turn, might lead to different outcomes of liver fibrosis. [source] Dyspnoea after antiplatelet agents: the AZD6140 controversyINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 3 2007V. L. Serebruany Summary Recent randomised studies suggest that experimental oral reversible platelet P2Y12 receptor inhibitor, AZD6140, causes dyspnoea. This also raises similar concerns about the parent compound, and another adenosine triphosphate (ATP) analogue (AR-69931MX or cangrelor), which is currently in Phase 3 trial in patients undergoing coronary interventions. We analysed package inserts, and available clinical trials safety data for antiplatelet agents with regard to the incidence of dyspnoea. We found that dyspnoea is a very rare complication of the presently approved platelet inhibitors, mostly caused by underlying disease, rather than antiplatelet therapy per se. The main reasons for respiratory distress after oral (AZD6140), and intravenous (cangrelor) agents may be the development of mild asymptomatic thrombotic thrombocytopenic purpura, fluid retention and dyspnoea because of the reversible nature of these drugs. Also, these agents are ATP analogues, which rapidly metabolise to adenosine, a well-known bronchoprovocator causing dyspnoea as well. In summary, dyspnoea is seldom considered, there are no treatment algorithms when it does occur, plausible mechanisms exist and despite these plausible mechanisms, the true cause of dyspnoea in these exposed individuals is unknown. Additional pulmonary function testing, immunological investigations and platelet receptor studies are urgently needed to determine the cause of dyspnoea after AZD6140, and to point out how such serious adverse reactions can be prevented, or at least minimised, raising potential concerns about this drug. [source] Nanoparticles as tools to study and control stem cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2009L. Ferreira Abstract The use of nanoparticles in stem cell research is relatively recent, although very significant in the last 5 years with the publication of about 400 papers. The recent advances in the preparation of some nanomaterials, growing awareness of material science and tissue engineering researchers regarding the potential of stem cells for regenerative medicine, and advances in stem cell biology have contributed towards the boost of this research field in the last few years. Most of the research has been focused in the development of new nanoparticles for stem cell imaging; however, these nanoparticles have several potential applications such as intracellular drug carriers to control stem cell differentiation and biosensors to monitor in real time the intracellular levels of relevant biomolecules/enzymes. This review examines recent advances in the use of nanoparticles for stem cell tracking, differentiation and biosensing. We further discuss their utility and the potential concerns regarding their cytotoxicity. J. Cell. Biochem. 108: 746,752, 2009. © 2009 Wiley-Liss, Inc. [source] Treatment of an explosives plume in groundwater using an organic mulch biowallREMEDIATION, Issue 1 2009Farrukh Ahmad A field demonstration of a mulch permeable reactive barrier (PRB), or "biowall," as an in situ treatment technology for explosives in groundwater is summarized. Organic mulch consists of insoluble carbon biopolymers that are enzymatically hydrolyzed during decomposition to release aqueous total organic carbon (TOC). The released TOC is then available for microorganisms to use as an electron donor to transform electrophilic contaminants via reductive pathways. A 100-foot-long and 2-foot-thick mulch biowall was installed at the Pueblo Chemical Army Depot in Colorado to treat a shallow groundwater plume containing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). To discourage groundwater flow bypassing around and under the biowall in this highly permeable formation, a hydraulic control was installed and the PRB was keyed into the bedrock. Technology performance was monitored using a monitoring well network to establish the development and extent of the downgradient treatment zone. Performance objectives of the field demonstration were: (1) greater than 90 percent removal of RDX across the PRB and the treatment zone; (2) an RDX concentration of less than 0.55 ,g/L in the treatment zone; and (3) cumulative toxic intermediate concentration (nitroso intermediates of RDX, MNX, DNX, and TNX) of less than 20 percent of the upgradient RDX concentration. All performance objectives were met within seven months after installation once the system reached a pseudo-steady state. By this point, a sustained reducing/treatment zone had been created downgradient of the mulch PRB that showed greater than 93 percent RDX removal, RDX concentrations less than 0.55 ,g/L, and no accumulation of toxic intermediates. The mulch biowall implemented during this demonstration was successful at meeting performance objectives while addressing the majority of potential concerns of the technology. © 2009 Wiley Periodicals, Inc. [source] Assessing indices of happiness and unhappiness in individuals with developmental disabilities: a reviewBEHAVIORAL INTERVENTIONS, Issue 3 2007Courtney M. Dillon The behavioral deficits of individuals with profound multiple disabilities (PMD) make it difficult to assess their satisfaction and quality of life. To address this problem, researchers have recently evaluated affective behavior (i.e., indices of happiness and unhappiness) to document the effects of therapeutic interventions and to assist with clinically relevant decisions. We review the recent literature on indices of happiness and unhappiness and discuss its major themes. In addition, potential concerns with this technology are discussed and clinical recommendations are provided. Copyright © 2007 John Wiley & Sons, Ltd. [source] Considerations for the Recovery of Recombinant Proteins from PlantsBIOTECHNOLOGY PROGRESS, Issue 4 2004Todd J. Menkhaus The past 5 years have seen the commercialization of two recombinant protein products from transgenic plants, and many recombinant therapeutic proteins produced in plants are currently undergoing development. The emergence of plants as an alternative production host has brought new challenges and opportunities to downstream processing efforts. Plant hosts contain a unique set of matrix contaminants (proteins, oils, phenolic compounds, etc.) that must be removed during purification of the target protein. Furthermore, plant solids, which require early removal after extraction, are generally in higher concentration, wider in size range, and denser than traditional bacterial and mammalian cell culture debris. At the same time, there remains the desire to incorporate highly selective and integrative separation technologies (those capable of performing multiple tasks) during the purification process from plant material. The general plant processing and purification scheme consists of isolation of the plant tissue containing the recombinant protein, fractionation of the tissue along with particle size reduction, extraction of the target protein into an aqueous medium, clarification of the crude extract, and finally purification of the product. Each of these areas will be discussed here, focusing on what has been learned and where potential concerns remain. We also present details of how the choice of plant host, along with location within the plant for targeting the recombinant protein, can play an important role in the ultimate ease of recovery and the emergence of regulations governing plant hosts. Major emphasis is placed on three crops, canola, corn, and soy, with brief discussions of tobacco and rice. [source] | |||||||||||||