993 resultados para environmental organisms
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Size-selective fishing, environmental changes and reproductive strategies are expected to affect life-history traits such as the individual growth rate. The relative contribution of these factors is not clear, particularly whether size-selective fishing can have a substantial impact on the genetics and hence on the evolution of individual growth rates in wild populations. We analysed a 25-year monitoring survey of an isolated population of the Alpine whitefish Coregonus palaea. We determined the selection differentials on growth rate, the actual change of growth rate over time and indicators of reproductive strategies that may potentially change over time. The selection differential can be reliably estimated in our study population because almost all the fish are harvested within their first years of life, i.e. few fish escape fishing mortality. We found a marked decline in average adult growth rate over the 25 years and a significant selection differential for adult growth, but no evidence for any linear change in reproductive strategies over time. Assuming that the heritability of growth in this whitefish corresponds to what was found in other salmonids, about a third of the observed decline in growth rate would be linked to fishery-induced evolution. Size-selective fishing seems to affect substantially the genetics of individual growth in our study population.
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A brief summary is given here about some of the geochemical methodologies that are often used to obtain information from fossils and sediments about the past environment. Such methods are frequently applied in our project in which the formation of Paleogene phosphate sequences in North Africa is investigated. These layers were deposited in shallow marine seas during a period of extreme warm climate with a high CO(2) concentration in the atmosphere. Some of the characteristics of this greenhouse interval are similar to the modern anthropogenic situation hence it is intensively investigated from several aspects by many scientists. Here the geochemical compositions of fossils deposited during this time are discussed, focusing on how the data are obtained and how they could be evaluated in terms of palaeo-environmental conditions.
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A passive sampling device called Monitor of NICotine or "MoNIC", was constructed and evaluated by IST laboratory for determining nicotine in Environmental Tobacco Smoke (ETS). Vapour nicotine was passively collected on a potassium bisulfate treated glass fibre filter as collection medium. Analysis of amount of nicotine on the treated filter by gas chromatography equipped with Thermoionic-Specific Detector (GCTSD) after liquid-liquid extraction of 1mL of 5N NaOH : 1 mL of n-heptane saturated with NH3 using quinoline as internal standard. Based on nicotine amount of 0.2 mg/cigarette as reference, the inhaled Cigarette Equivalents (CE) by non-smokers can be calculated. Using the detected CE on the badge for nonsmokers, and comparing with amount of nicotine and cotinine level in saliva of both smokers and exposed non-smokers (N=49), we can confirm the use of the CE concept for estimating exposure to ETS. The Valais CIPRET (Center of information and prevention of the addiction to smoking), is going to organize a big campaign on the subject of the passive addiction to smoking entitled "Smoked passive, we suffer from it, we die from it ". This campaign will take place in 2007 and has for objective to inform clearly the population of Valais of the dangerousness of the passive smoke. More than 1'500 MoNIC badges were gracefully distributed to Swiss population to perform a self-monitoring of population exposure level to ETS, expressed in term of CE. Non-stimulated saliva were also collected to determine ETS biomarkers nicotine/cotinine levels of participating volunteers. Preliminary results of different levels of CE in occupational and non-occupational situations in relation with ETS were presented in this study.
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Background: Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation due to dysregulation of the mucosal immune system. The cytokines IL-1β and IL-18 appear early in intestinal inflammation and their pro-forms are processed via the caspase-1-activating multiprotein complex, the Nlrp3 inflammasome. Previously, we reported that the uptake of dextran sodium sulfate (DSS) by macrophages activates the Nlrp3 inflammasome and that Nlrp3(-/-) mice are protected in the acute DSS colitis model. Of note, other groups have reported opposing effects in regards to DSS susceptibility in Nlrp3(-/-) mice. Recently, mice lacking inflammasomes were found to develop a distinct intestinal microflora. Methods: To reconcile the contradicting observations, we investigated the role of Nlrp3 deficiency in two different IBD models: acute DSS colitis and TNBS (2,4,6-trinitrobenzene sulfonic acid)-induced colitis. In addition, we investigated the impact of the intestinal flora on disease severity by performing cohousing experiments of wild-type and Nlrp3(-/-) mice, as well as by antibiotic treatment. Results: Nlrp3(-/-) mice treated with either DSS or TNBS exhibited attenuated colitis and lower mortality. This protective effect correlated with an increased frequency of CD103+ lamina propria dendritic cells expressing a tolerogenic phenotype in Nlrp3(-/-) mice in steady state conditions. Interestingly, after cohousing, Nlrp3(-/-) mice were as susceptible as wild-type mice, indicating that transmission of endogenous bacterial flora between the two mouse strains might increase susceptibility of Nlrp3(-/-) mice towards DSS-induced colitis. Accordingly, treatment with antibiotics almost completely prevented colitis in the DSS model. Conclusions: The composition of the intestinal microflora significantly influences disease severity in IBD models comparing wild-type and Nlrp3(-/-) mice. This observation may - at least in part - explain contradictory results concerning the role of the inflammasome in different labs. Further studies are required to define the role of the Nlrp3 inflammasome in noninflamed mucosa under steady state conditions and in IBD.
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We present an integrated work based on calcareous nannofossil and benthic foraminiferal assemblages, and geochemical analyses of two Upper Pliensbachian-Lower Toarcian sections located in the central-South France. The studied sections, Tournadous and Saint-Paul-des-Fonts, represent the proximal and the distal part, respectively, of the Jurassic Causses Basin, one of the small, partly enclosed basins belonging to the epicontinental shelf of the NW Tethys. At the transition from Late Pliensbachian to Early Toarcian, the Causses Basin recorded an emersion in response to the global sea-level fall. Our data indicate severe environmental conditions of marine waters, including salinity decrease and anoxia development, occurring in the Early Toarcian. The acme of this deterioration coincides with the Early Toarcian Anoxic Event (T-OAE) but, due to the restricted nature of the basin. anoxia persisted until the end of the Early Toarcian. mainly in the deeper parts of the basin. The micronutrients and organic organic-matter fluxes were probably high during the entire studied time interval, as shown by nannofossil and foraminiferal assemblages. However, nannoplankton production drastically decreased during the T-OAE, as demonstrated by very low nannofossil fluxes, and only taxa tolerant to low-saline surface waters could thrive. At the same time, benthic foraminifers temporarily disappeared in response to sea-bottom anoxia. Our study demonstrates that environmental changes related to the T-OAE are well-recorded even in small, partly enclosed basins of NW Europe, like the Causses Basin. Within this area, the effects of global changes. like sea sea-level and temperature fluctuations, are modulated by local conditions mainly controlled by the morphology of the basin. (C) 2008 Elsevier B.V. All rights reserved.
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Environmental chemicals with estrogenic activities have been suggested to be associated with deleterious effects in animals and humans. To characterize estrogenic chemicals and their mechanisms of action, we established in vitro and cell culture assays that detect human estrogen receptor [alpha] (hER[alpha])-mediated estrogenicity. First, we assayed chemicals to determine their ability to modulate direct interaction between the hER[alpha] and the steroid receptor coactivator-1 (SRC-1) and in a competition binding assay to displace 17ss-estradiol (E(2)). Second, we tested the chemicals for estrogen-associated transcriptional activity in the yeast estrogen screen and in the estrogen-responsive MCF-7 human breast cancer cell line. The chemicals investigated in this study were o,p'-DDT (racemic mixture and enantiomers), nonylphenol mixture (NPm), and two poorly analyzed compounds in the environment, namely, tris-4-(chlorophenyl)methane (Tris-H) and tris-4-(chlorophenyl)methanol (Tris-OH). In both yeast and MCF-7 cells, we determined estrogenic activity via the estrogen receptor (ER) for o,p'-DDT, NPm, and for the very first time, Tris-H and Tris-OH. However, unlike estrogens, none of these xenobiotics seemed to be able to induce ER/SRC-1 interactions, most likely because the conformation of the activated receptor would not allow direct contacts with this coactivator. However, these compounds were able to inhibit [(3)H]-E(2) binding to hER, which reveals a direct interaction with the receptor. In conclusion, the test compounds are estrogen mimics, but their molecular mechanism of action appears to be different from that of the natural hormone as revealed by the receptor/coactivator interaction analysis.
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BACKGROUND: The role of video-assisted thoracoscopic surgery in the treatment of pleural empyema was assessed in a consecutive series of 328 patients between 1992 and 2002. An analysis of the predicting factors for conversion thoracotomy in presumed stage II empyema was performed. METHODS: Empyema stage III with pleural thickening and signs of restriction on computer tomography imaging was treated by open decortication, whereas a thoracoscopic debridement was attempted in presumed stage II disease. Conversion thoracotomy was liberally used during thoracoscopy if stage III disease was found at surgery. Predictive factors for conversion thoracotomy were calculated in a multivariate analysis among several variables such as age, sex, time interval between onset of symptoms and surgery, involved microorganisms, and underlying cause of empyema. RESULTS: Of the 328 patients surgically treated for stage II and III empyema, 150 underwent primary open decortication for presumed stage III disease. One hundred seventy-eight patients with presumed stage II empyema underwent a video-assisted thoracoscopic approach. Of these 178 patients, thoracoscopic debridement was successful in 99 of 178 patients (56%), and conversion thoracotomy and open decortication was judged necessary in 79 of 178 patients (44%). The conversion thoracotomy rate was higher in parapneumonic empyema (55%) as compared with posttraumatic (32%) or postoperative (29%) empyema; however, delayed referral (p < 0.0001) and gram-negative microorganisms (p < 0.01) were the only significant predictors for conversion thoracotomy in a multivariate analysis. CONCLUSIONS: Video-assisted thoracoscopic debridement offers an elegant, minimally invasive approach in a number of patients with presumed stage II empyema. However, to achieve a high success rate with the video-assisted thoracoscopic approach, early referral of the patients to surgery is required. Conversion thoracotomy should be liberally used in case of chronicity, especially after delayed referral (> 2 weeks) and in the presence of gram-negative organisms.
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Este estudo teve como objetivo realizar a adaptação cultural do The Environmental Stressor Questionnaire - (ESQ) para a língua portuguesa do Brasil e verificar sua confiabilidade e validade. Foram empregadas as etapas metodológicas recomendadas pela literatura para adaptação cultural. A versão brasileira do ESQ foi aplicada a 106 pacientes de Unidade de Terapia Intensiva (UTI) de dois hospitais, público e privado, do interior do Estado de São Paulo. A confiabilidade foi avaliada quanto à consistência interna e estabilidade (teste e reteste); a validade convergente foi verificada por meio da correlação entre o ESQ e questão genérica sobre estresse em UTI. A confiabilidade foi satisfatória com Alfa de Crombach=0,94 e Coeficiente de Correlação Intraclasse=0,861 (IC95% 0,723; 0,933). Constatou-se correlação entre o escore total do ESQ e a questão genérica sobre estresse (r=0,70), confirmando a validade convergente. A versão brasileira do ESQ mostrou-se uma ferramenta confiável e válida para avaliação de estressores em UTI.
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Background: Awareness of the negative effects of smoking on children's health prompted a decrease in the self-reporting of parental tobacco use in periodic surveys from most industrialized countries. Our aim is to assess changes between ETS exposure at the end of pregnancy and at 4 years of age determined by the parents' self-report and measurement of cotinine in age related biological matrices.Methods: The prospective birth cohort included 487 infants from Barcelona city (Spain). Mothers were asked about maternal and household smoking habit. Cord serum and children's urinary cotinine were analyzed in duplicate using a double antibody radioimmunoassay. Results: At 4 years of age, the median urinary cotinine level in children increased 1.4 or 3.5 times when father or mother smoked, respectively. Cotinine levels in children's urine statistically differentiated children from smoking mothers (Geometric Mean (GM) 19.7 ng/ml; 95% CI 16.83–23.01) and exposed homes (GM 7.1 ng/ml; 95% CI 5.61–8.99) compared with non-exposed homes (GM 4.5 ng/ml; 95% CI 3.71–5.48). Maternal self-reported ETS exposure in homes declined in the four year span between the two time periods from 42.2% to 31.0% (p < 0.01). Nevertheless, most of the children considered non-exposed by their mothers had detectable levels of cotinine above 1 ng/mL in their urine.Conclusion: We concluded that cotinine levels determined in cord blood and urine, respectively, were useful for categorizing the children exposed to smoking and showed that a certain increase in ETS exposure during the 4-year follow-up period occurred.
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A procedure was developed for determining 241Pu activity in environmental samples. This beta emitter isotope of plutonium was measured by ultra low level liquid scintillation, after several separation and purification steps that involved the use of a highly selective extraction chromatographic resin (Eichrom-TEVA). Due to the lack of reference material for 241Pu, the method was nevertheless validated using four IAEA reference sediments with information values for 241Pu. Next, the method was used to determine the 241Pu activity in alpine soils of Switzerland and France. The 241Pu/239,240Pu and 238Pu/239,240Pu activity ratios confirmed that Pu contamination in the tested alpine soils originated mainly from global fallout from nuclear weapon tests conducted in the fifties and sixties. Estimation of the date of the contamination, using the 241Pu/241Am age-dating method, further confirmed this origin. However, the 241Pu/241Am dating method was limited to samples where Pu-Am fractionation was insignificant. If any, the contribution of the Chernobyl accident is negligible.
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The United States has invested large sums of resources in multiple conservation programs for agriculture over the past century. In this paper we focus on the impacts of program interactions. Specifically, using an integrated economic and bio-physical modeling framework, we consider the impacts of the presence of working land programs on a land retirement for an important agricultural region—the Upper Mississippi River Basin (UMRB). Compared to a land retirement only program, we find that the presence of a working land program for conservation tillage results in significantly lower predicted signups for land retirement at a given rental rate. We also find that the presence of both a large working land and land retirement program can result in more environmental benefits and income transfers than a land retirement only program can achieve.