Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 31
Filtrar
1.
J Antimicrob Chemother ; 79(5): 1045-1050, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38507272

RESUMO

OBJECTIVES: Staphylococcus epidermidis bone and joint infections (BJIs) on material are often difficult to treat. The activity of delafloxacin has not yet been studied on S. epidermidis in this context. The aim of this study was to assess its in vitro activity compared with other fluoroquinolones, against a large collection of S. epidermidis clinical strains. METHODS: We selected 538 S. epidermidis strains isolated between January 2015 and February 2023 from six French teaching hospitals. One hundred and fifty-two strains were ofloxacin susceptible and 386 were ofloxacin resistant. Identifications were performed by MS and MICs were determined using gradient concentration strips for ofloxacin, levofloxacin, moxifloxacin and delafloxacin. RESULTS: Ofloxacin-susceptible strains were susceptible to all fluoroquinolones. Resistant strains had higher MICs of all fluoroquinolones. Strains resistant to ofloxacin (89.1%) still showed susceptibility to delafloxacin when using the Staphylococcus aureus 2021 CA-SFM/EUCAST threshold of 0.25 mg/L. In contrast, only 3.9% of the ofloxacin-resistant strains remained susceptible to delafloxacin with the 0.016 mg/L S. aureus breakpoint according to CA-SFM/EUCAST guidelines in 2022. The MIC50 was 0.094 mg/L and the MIC90 was 0.38 mg/L. CONCLUSIONS: We showed low delafloxacin MICs for ofloxacin-susceptible S. epidermidis strains and a double population for ofloxacin-resistant strains. Despite the absence of breakpoints for S. epidermidis, delafloxacin may be an option for the treatment of complex BJI, including strains with MICs of ≤0.094 mg/L, leading to 64% susceptibility. This study underlines the importance for determining specific S. epidermidis delafloxacin breakpoints for the management of BJI on material.


Assuntos
Antibacterianos , Fluoroquinolonas , Testes de Sensibilidade Microbiana , Infecções Estafilocócicas , Staphylococcus epidermidis , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/isolamento & purificação , Humanos , Fluoroquinolonas/farmacologia , Antibacterianos/farmacologia , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/tratamento farmacológico , Estudos Retrospectivos , Ofloxacino/farmacologia , Levofloxacino/farmacologia , Farmacorresistência Bacteriana , Moxifloxacina/farmacologia , França
2.
Eur J Clin Microbiol Infect Dis ; 43(2): 395-399, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38093085

RESUMO

We report two uncommon cases of osteosynthetic cervical spine infection. Clinical patient features, microbiological strain characteristics, diagnostic methods, and treatment were analyzed. Both patients were male, and one had risk factors for surgical site infection. During surgery, perioperative samples were positive yielding an anaerobic microorganism identified as Cutibacterium namnetense by MALDI-TOF MS and confirmed by 16S rRNA/gyrB genes sequencing. All isolates were fully susceptible. C. namnetense osteosynthetic cervical spine infections are rare. Both cases were early surgical site infections. Bruker MALDI-TOF MS appears to be an excellent tool for rapid and accurate identification. Amoxicillin seems to be an option for the treatment.


Assuntos
Propionibacteriaceae , Humanos , Masculino , Feminino , RNA Ribossômico 16S/genética , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Vértebras Cervicais
4.
Eur J Clin Microbiol Infect Dis ; 42(8): 1031-1036, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37256456

RESUMO

Septic arthritis is a diagnostic emergency. The white blood cell (WBC) count, in synovial fluid (SF), can guide the diagnosis. From November 2021 to November 2022, we included 350 SF. The WBC count was performed with the Iris iQ® 200 compared with the manual method. Automated and manual counts displayed good correlation. However, a Bland Altman plot demonstrates a higher percentage difference at higher WBC counts. The use of Iris iQ® 200 for SF analysis enables a rapid and accurate assessment for WBC count. Its implementation would advantageously replace the long and tedious optical analysis in daily routine.


Assuntos
Artrite Infecciosa , Líquido Sinovial , Humanos , Líquido Sinovial/microbiologia , Artrite Infecciosa/diagnóstico , Contagem de Leucócitos
5.
Aquat Toxicol ; 258: 106474, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36893699

RESUMO

Methylmercury (MeHg) is a ubiquitous bioaccumulative neurotoxicant present in aquatic ecosystems. It is known to alter behaviors, sensory functions and learning abilities in fish and other vertebrates. Developmental and early-life stages exposure to MeHg can lead to brain damage with immediate consequences on larvae behavior, but may also induce long term effects in adults after a detoxification period. However, very little is known about developmental origin of behavioral impairment in adults due to early exposure to MeHg. The aim of this study is to assess whether early-life MeHg exposure induces immediate and/or delayed effects on behaviors, related genes expression and DNA methylation (one of epigenetic mechanisms). To reach this goal, newly hatched larvae of mangrove rivulus fish, Kryptolebias marmoratus, were exposed to two sub-lethal concentrations of MeHg (90 µg/L and 135 µg/L) for 7 days, and immediate and delayed effects were assessed respectively in 7 dph (days post-hatching) and 90 dph fish. This species naturally produces isogenic lineages due to its self-fertilizing reproduction system, which is unique among vertebrates. It allows to study how environment stressors can influence organism's phenotype while minimizing genetic variability. As results, both MeHg exposures are associated with a decreased foraging efficiency and thigmotaxis, and a dose-dependent reduction in larvae locomotor activity. Regarding molecular analysis in larvae whole bodies, both MeHg exposures induced significant decreased expression of DNMT3a, MAOA, MeCP2 and NIPBL, and significant increase of GSS, but none of those genes underwent methylation changes in targeted CpGs. None of significant behavioral and molecular impairments observed in 7-dph larvae were found in 90-dph adults, which highlight a distinction between immediate and delayed effects of developmental MeHg exposure. Our results suggest implications of aminergic system and its neurotransmitters, redox/methylation trade-off and possibly other epigenetic mechanisms in MeHg neurotoxicity underlying behavioral alterations in rivulus.


Assuntos
Ciprinodontiformes , Peixes Listrados , Compostos de Metilmercúrio , Poluentes Químicos da Água , Animais , Compostos de Metilmercúrio/toxicidade , Ecossistema , Poluentes Químicos da Água/toxicidade , Peixes Listrados/genética , Ciprinodontiformes/genética , Larva , Expressão Gênica
6.
Microbiol Spectr ; 10(5): e0130122, 2022 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-35980223

RESUMO

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge. BV represents a dysbiosis with the acquisition of a diverse community of anaerobic bacteria and a reduction in lactobacilli burden. Our objective was to evaluate the Aptima BV assay kit for the diagnosis of BV. From May to August 2019, we enrolled outpatients and inpatients, including nonpregnant women above 18 with vaginosis symptoms, consulting at Nantes University hospital. The Aptima BV assay measures the loads of Gardnerella vaginalis, Atopobium vaginae, and Lactobacillus species in relation to overall bacterial load. The Aptima BV assay was compared to Nugent scoring (NS). A total of 456 women were enrolled, and 347 patients met the inclusion criteria with data available for the analysis. NS was used to classify the samples and 144 (41.5%) samples were classified as normal (NS = 0-3), 45 (13%) as BV (NS = 7-10), 38 (11%) presented an intermediate vaginal microbiota (3 < NS < 7), 79 (22.7%) had various bacteria (excluding vaginal flora), 29 (8.3%) had insufficient bacterial density, and 12 (3.5%) had a predominance of yeasts. The Aptima BV kit displayed a sensitivity of 91.1% and specificity of 94.4% with a positive predictive value (PPV) of 83.7% and a negative predictive (NPV) value of 97.1%. The results of this monocentric retrospective study show that Aptima BV kit has a good diagnostic correlation compared to standard of care for dysbiotic diagnosis cases. IMPORTANCE The possibility exists of the involvement of a new molecular test in the routine algorithm of bacterial vaginosis diagnosis in microbiology laboratories. This manuscript reports on our experience, and we propose an organization combining Nugent scoring and molecular testing, especially for intermediate Nugent scores.


Assuntos
Vaginose Bacteriana , Humanos , Feminino , Vaginose Bacteriana/diagnóstico , Vaginose Bacteriana/microbiologia , Estudos Retrospectivos , Gardnerella vaginalis , Vagina/microbiologia , Lactobacillus , Bactérias/genética , Hospitais
7.
BJOG ; 129(3): 485-492, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34324258

RESUMO

OBJECTIVE: To identify risk factors for a woman to experience pregnancy denial. DESIGN, SETTING AND POPULATION: A French multicentric prospective case-control study with 71 mother-infant dyads having experienced a pregnancy denial versus a control group of 71 dyads. METHODS: Data were collected in the week after delivery using an observational leaflet and two psychiatric scales (MINI and QSSP). MAIN OUTCOME MEASURES: Statistically significant differences between the two groups regarding social, demographic, medical and psychiatric data. RESULTS: Not being in a stable relationship (odds ratio [OR] 17.18, 95% CI 3.37-87.60]; P < 0.0001), not having a high school diploma (OR 1.11, 95% CI 1.04-1.38]; P < 0.0001) and having a psychiatric history (OR 6.33, 95% CI 1.62-24.76; P = 0.0002) were risk factors to experience pregnancy denial, whereas being older was a protective factor (OR 0.86, 95% CI 0.79-0.93; P = 0.0054) (logistic regression, Wald 95% CI). Other risk factors included late declarations of pregnancy history and past pregnancy denials (case n = 7, 9.7% versus 0% in controls; P = 0.01), past pregnancy denials in the family (case n = 13, 18% versus control n = 4, 5.6%; P = 0.03), and use of a contraceptive method (75% for cases versus 7% in control; P < 0.0001), primarily an oral contraceptive (75%). CONCLUSION: Family or personal history of pregnancy denial should be part of the systematic anamnesis during the first visit of a patient of child-bearing age. Further, our study points out that life context (young age, single status, socio-economic precarity, pill-based contraception) could be a trigger for pregnancy denial in certain women. TWEETABLE ABSTRACT: Life context can be a trigger for pregnancy denial.


Assuntos
Negação em Psicologia , Gravidez não Planejada/psicologia , Adulto , Estudos de Casos e Controles , Anticoncepção/psicologia , Anticoncepção/estatística & dados numéricos , Escolaridade , Feminino , França , Humanos , Modelos Logísticos , Idade Materna , Razão de Chances , Gravidez , Estudos Prospectivos , Fatores de Risco , Adulto Jovem
8.
Vaccine ; 38(15): 3149-3156, 2020 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-31980192

RESUMO

Schools are increasingly being used to deliver vaccines. In 2015/16 three school-based vaccination programmes were delivered to adolescents in England: human papillomavirus (HPV), meningococcal groups A, C, W and Y disease (MenACWY) and tetanus, diphtheria and polio (Td/IPV). We assessed how school delivery models impact vaccine coverage and how a delivery model for one programme may impact another. Routinely collected national data were analysed to ascertain the school grade achieving highest coverage within each one-dose programme and to compare two-dose delivery models (within year vs across years) for the HPV vaccine. We also assessed whether the HPV delivery model was associated with coverage in other programmes. MenACWY and Td/IPV coverage was highest in younger school grades. Overall similar HPV coverage was achieved with both models (86.7% two doses within one year, 85.8% two doses across two years, p = 0.20). High two-dose HPV coverage in 2015/16 was reported in areas that achieved high HPV coverage in 2013/14 when three doses were required. Areas with high three-dose coverage in 2013/14 achieved higher coverage with a within-one-year approach (92.0% vs 85.2%, p < 0.001), whilst areas reporting low coverage in 2013/14 achieved lower but similar coverage in 2015/16 with both models (79.2% vs 80.9% p = 0.29). MenACWY and Td/IPV coverage were higher in areas with high HPV coverage in 2013/14. Among high HPV coverage areas, MenACWY coverage was higher when HPV doses were delivered within year. School-based programmes should be offered as early as feasible and acceptable to optimise coverage. The choice of delivery model for HPV should take into account local performance and provider experience. Single providers may delivery multiple vaccines and the delivery for one programme may affect the performance of other programmes. Providers should consider local circumstances including past and current vaccine coverage and factors influencing coverage when deciding what delivery model to adopt.


Assuntos
Programas de Imunização/organização & administração , Vacinas contra Papillomavirus/administração & dosagem , Serviços de Saúde Escolar/organização & administração , Adolescente , Criança , Inglaterra , Humanos , Papillomaviridae
9.
J Hazard Mater ; 367: 715-724, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30682658

RESUMO

The concentrations of inorganic mercury (IHg) and methylmercury (MeHg) in surface sediments from the contaminated Aveiro Lagoon (Portugal) were determined by species-specific isotope dilution analysis. Different behaviour of IHg and MeHg was observed based upon multiple regression analysis, including geochemical characteristics of the surface sediments (fine fraction, concentrations of organic matter and metals) and non-Euclidean distances between sampling points. This data treatment method was valid over the entire concentration range of IHg and MeHg, allowing robust quantitative evaluation with respect to extrapolation. For IHg, there was statistical separation of the dispersion away from the contamination source and of Al concentration in the sediments. The MeHg concentrations followed those of IHg at high concentrations. The geochemical variables, such as concentrations of Ca (marine influence proxy), Mn and organic matter, were necessary to describe the behaviour of MeHg across the whole concentration range. The models for MeHg demonstrated that, close to the mouth of the lagoon, net production of MeHg was higher. In future, multiple regression analysis could be applied to separate and to evaluate quantitatively the effects of geochemistry and dispersion away from the contamination source in sediments contaminated with other substances.

10.
Environ Sci Technol ; 52(20): 11573-11582, 2018 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-30222337

RESUMO

We used natural mercury (Hg) stable isotopes to investigate the Hg cycle in a rainforest soil catena (French Guiana) partially gold-mined during the early 1950s. Litterfall showed homogeneous Δ199Hg values [-0.18 ± 0.05‰, i.e., a modern gaseous elemental Hg (GEM) isotopic signature]. After litter decomposition, Hg bound to organic matter (OM) is mixed with Hg from pristine (-0.55 ± 0.22‰) or gold-mined (-0.09 ± 0.16‰) mineral materials. Negative Δ199Hg values in deep pristine mineral horizons (-0.60 ± 0.16‰) suggest the transfer of Hg bound to dissolved OM depleted in odd isotopes due to mass-independent fractionation during Hg abiotic reduction. Perennial palm tree leaves collected above gold-mined and pristine soil recorded contrasting Δ199Hg signatures likely resulting from GEM re-emission processes from soils and leaf surfaces. Upslope, soil δ202Hg signatures showed a negative shift (ε ∼ -1‰) with depth attributed to mass-dependent fractionation during Hg sorption and complexation onto iron oxides and dissolved OM. Downslope, higher δ202Hg values in soils resulted from hydromorphy [lower humification, greater Hg(II) reduction, etc.]. The unique Hg isotopic signatures of Amazonian soils probably result in multistep fractionation processes during pedogenesis (millions of years) and in a potentially different Hg isotopic signature of preanthropogenic background GEM.


Assuntos
Mercúrio , Solo , Monitoramento Ambiental , Florestas , Guiana Francesa , Ouro , Isótopos de Mercúrio , Mineração
11.
Vaccine ; 36(23): 3231-3238, 2018 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-29716775

RESUMO

England's influenza vaccination programme targets persons with clinical risk factors, pregnant women, those aged 65 years and older and children. Low vaccine uptake amongst primary school children was previously found to be significantly associated with increasing deprivation, Black or Minority Ethnic (BME) and certain religions. It is unknown whether these population predictors are associated with vaccine uptake in other groups. GP level data for target groups during the 2015/16 and 2016/17 seasons were linearly regressed against various factors to determine potential predictors associated with variation in uptake. Adjusted uptake for 2-4 year olds during both seasons was more than 11% lower in the most deprived decile and more than 3% lower in 34%+ BME populations compared to the least deprived and non-BME populations. Pregnant women in deprived areas had significantly lower vaccine uptake than in non-deprived areas. Patients 16-64 years old at risk showed no significant variation in uptake by deprivation, whereas patients 65 years and older had more than 3% higher vaccine uptake in the least deprived populations than the most deprived populations. Areas with the highest Muslim and BME populations had a significantly higher vaccine uptake among patients ages 16 to under 65 years old in a clinical risk group than non-Muslim and non-BME populations during both seasons. Population-factors have different effects on vaccine uptake for the various target groups. These findings support segmenting public health activities to improve vaccine uptake and reduce inequalities.


Assuntos
Programas de Imunização/estatística & dados numéricos , Vacinas contra Influenza/uso terapêutico , Adolescente , Adulto , Idoso , Pré-Escolar , Inglaterra , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Grupos Minoritários , Gravidez , Fatores de Risco
12.
J Chromatogr A ; 1547: 77-85, 2018 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-29555356

RESUMO

The current EU legislation lays down Environmental Quality Standards (EQS) for 45 priority substances in surface waters; among them levels for (organo)metallic species of Hg, Sn and Pb are set between ng L-1 (for Hg and Sn) and µg L-1 (for Pb). To date, only a few analytical methods can reach these very restrictive limits and there is thus a need for comprehensive methods able to analyze these species down to these levels in natural waters. The aim of this work was to develop an online automated pre-concentration method using large volume injections with a Programmed Temperature Vaporization (PTV) injector fitted with a sorbent packed liner coupled to GC-ICP-MS to further improve the detection limits associated to this well-established method. The influence of several parameters such as the PTV transfer temperature and time, carrier gas flow rate and amount of packing material was investigated. Finally, the maximum volume injected through single or multiple injection modes was optimized to obtain the best compromise between chromatographic resolution and sensitivity. After optimization, very satisfactory results in terms of absolute and methodological detection limits were achieved, down to the pg L-1 level for all species studied. The potential of the method was exemplified by determining the concentrations of organometallic compounds in unpolluted river waters samples from the Adour river basin (SW France) and results were compared with conventional (splitless) GC-ICP-MS. The strength of this analytical method lies in the low detection limits reached for the simultaneous analysis of a wide group of organometallic compounds, and the potential to transfer this method to other gas chromatographic applications with inherent lower sensitivity.


Assuntos
Cromatografia Gasosa/instrumentação , Cromatografia Gasosa/métodos , Chumbo/análise , Mercúrio/análise , Temperatura , Estanho/análise , Poluentes Químicos da Água/análise , França , Limite de Detecção , Espectrometria de Massas/métodos , Reprodutibilidade dos Testes , Rios/química , Volatilização
13.
Environ Pollut ; 231(Pt 1): 262-270, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28806691

RESUMO

Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.


Assuntos
Monitoramento Ambiental , Lagos/química , Mercúrio/análise , Poluentes Químicos da Água/análise , Animais , Bolívia , Ecossistema , Eutrofização , Peixes , Cadeia Alimentar , Mineração , Plâncton
14.
Environ Sci Process Impacts ; 18(12): 1550-1560, 2016 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-27878175

RESUMO

Lake Uru Uru (3686 m a.s.l.) located in the Bolivian Altiplano region receives both mining effluents and urban wastewater discharges originating from the surrounding local cities which are under rapid development. We followed the spatiotemporal distribution of different mercury (Hg) compounds and other metal(oid)s (e.g., Fe, Mn, Sb, Ti and W) in both water and sediments during the wet and dry seasons along a north-south transect of this shallow lake system. Along the transect, the highest Hg and metal(oid) concentrations in both water and sediments were found downstream of the confluences with mining effluents. Although a dilution effect was found for major elements during the wet season, mean Hg and metal(oid) concentrations did not significantly differ from the dry season due to the increase in acid mine drainage (AMD) inputs into the lake from upstream mining areas. In particular, high filtered (<0.45 µm) mono-methylmercury (MMHg) concentrations (0.69 ± 0.47 ng L-1) were measured in surface water representing 49 ± 11% of the total filtered Hg concentrations (THgF) for both seasons. Enhanced MMHg lability in relation with the water alkalinity, coupled with abundant organic ligands and colloids (especially for downstream mining effluents), are likely factors favoring Hg methylation and MMHg preservation while inhibiting MMHg photodegradation. Lake sediments were identified as the major source of MMHg for the shallow water column. During the dry season, diffusive fluxes were estimated to be 227 ng m-2 d-1 for MMHg. This contribution was found to be negligible during the wet season due to a probable shift of the redox front downwards in the sediments. During the wet season, the results obtained suggest that various sources such as mining effluents and benthic or macrophytic biofilms significantly contribute to MMHg inputs in the water column. This work demonstrates the seasonally dependent synergistic effect of AMD and urban effluents on the shallow, productive and evaporative high altitude lake ecosystems which promotes the formation of natural organometallic toxins such as MMHg in the water column.


Assuntos
Lagos/química , Mercúrio/análise , Metais Pesados/análise , Compostos de Metilmercúrio/análise , Mineração , Águas Residuárias/análise , Poluentes Químicos da Água/análise , Bolívia , Cidades , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos/química , Estações do Ano
15.
J Hazard Mater ; 318: 711-722, 2016 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-27484944

RESUMO

Spatial and seasonal variation of mercury species aqueous concentrations and distributions was carried out during six sampling campaigns at four locations within Laranjo Bay, the most mercury-contaminated area of the Aveiro Lagoon (Portugal). Inorganic mercury (IHg(II)) and methylmercury (MeHg) were determined in filter-retained (IHgPART, MeHgPART) and filtered (<0.45µm) fractions (IHg(II)DISS, MeHgDISS). The concentrations of IHgPART depended on site and on dilution with downstream particles. Similar processes were evidenced for MeHgPART, however, its concentrations increased for particles rich in phaeophytin (Pha). The concentrations of MeHgDISS, and especially those of IHg(II)DISS, increased with Pha concentrations in the water. Multiple regression models are able to depict MeHgPART, IHg(II)DISS and MeHgDISS concentrations with salinity and Pha concentrations exhibiting additive statistical effects and allowing separation of possible addition and removal processes. A link between phytoplankton/algae and consumers' grazing pressure in the contaminated area can be involved to increase concentrations of IHg(II)DISS and MeHgPART. These processes could lead to suspended particles enriched with MeHg and to the enhancement of IHg(II) and MeHg availability in surface waters and higher transfer to the food web.


Assuntos
Compostos de Mercúrio/química , Compostos de Mercúrio/metabolismo , Plâncton/metabolismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluição Química da Água/análise , Algoritmos , Biomassa , Cadeia Alimentar , Compostos de Metilmercúrio/química , Compostos de Metilmercúrio/metabolismo , Portugal , Análise de Regressão , Estações do Ano
16.
Environ Monit Assess ; 188(1): 47, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26687090

RESUMO

Total mercury (HgTOT), inorganic mercury (IHg), and methylmercury (MHg) were determined in dry season waters, sediments, and tailings from an active mine which has long history of gold exploitation. Although HgTOT in waters was generally low (0.03 to 19.60 ng L(-1)), the majority of the samples had proportions of MHg of at least 90 % of HgTOT which denotes a substantial methylation potential of the mine watersheds. Mercury was relatively high in tailing materials (up to 867 µg kg(-1)) and also in the mine sediments (up to 837 µg kg(-1)) especially in samples collected near tailing storage facilities and within a receiving water dam. Sediment profiles revealed mercury enrichment and enhanced methylation rate at deeper layers. The presence of IHg and decaying plants (organic matter) in the watersheds as well as the anoxic conditions of bulk sediments are believed to be some of the key factors favoring the mercury methylation at the site.


Assuntos
Monitoramento Ambiental , Mercúrio/análise , Mineração , Poluentes Químicos da Água/análise , Água Doce , Sedimentos Geológicos , Ouro , Compostos de Metilmercúrio , África do Sul , Água
17.
Environ Sci Pollut Res Int ; 23(7): 6919-33, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26676541

RESUMO

Methylation and demethylation represent major transformation pathways regulating the net production of methylmercury (MMHg). Very few studies have documented Hg reactivity and transformation in extreme high-altitude lake ecosystems. Mercury (Hg) species concentrations (IHg, MMHg, Hg°, and DMHg) and in situ Hg methylation (M) and MMHg demethylation (D) potentials were determined in water, sediment, floating organic aggregates, and periphyton compartments of a shallow productive Lake of the Bolivian Altiplano (Uru Uru Lake, 3686 m). Samples were collected during late dry season (October 2010) and late wet season (May 2011) at a north (NS) and a south (SS) site of the lake, respectively. Mercury species concentrations exhibited significant diurnal variability as influenced by the strong diurnal biogeochemical gradients. Particularly high methylated mercury concentrations (0.2 to 4.5 ng L(-1) for MMHgT) were determined in the water column evidencing important Hg methylation in this ecosystem. Methylation and D potentials range were, respectively, <0.1-16.5 and <0.2-68.3 % day(-1) and were highly variable among compartments of the lake, but always higher during the dry season. Net Hg M indicates that the influence of urban and mining effluent (NS) promotes MMHg production in both water (up to 0.45 ng MMHg L(-1) day(-1)) and sediment compartments (2.0 to 19.7 ng MMHg g(-1) day(-1)). While the sediment compartment appears to represent a major source of MMHg in this shallow ecosystem, floating organic aggregates (dry season, SS) and Totora's periphyton (wet season, NS) were found to act as a significant source (5.8 ng MMHg g(-1) day(-1)) and a sink (-2.1 ng MMHg g(-1) day(-1)) of MMHg, respectively. This work demonstrates that high-altitude productive lake ecosystems can promote MMHg formation in various compartments supporting recent observations of high Hg contents in fish and water birds.


Assuntos
Monitoramento Ambiental , Lagos/química , Mercúrio/análise , Poluentes Químicos da Água/análise , Altitude , Animais , Bolívia , Ecossistema , Meio Ambiente , Peixes/metabolismo , Compostos de Metilmercúrio/química , Mineração , Estações do Ano
18.
Anal Bioanal Chem ; 406(4): 1253-8, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24136249

RESUMO

The aim of this work is to compare simultaneous isotope dilution analysis of organotin and organomercury compounds by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP/MS) on certified bivalve samples. These samples were extracted by microwave with tetramethylammonium hydroxide (TMAH). Derivatization with both NaBEt4 and NaBPr4 was evaluated, and analytical performances were compared. Two CRM materials, BCR-710 and CRM-477, were analyzed by both techniques to verify accuracy. A mixed spike containing (201)Hg-enriched methylmercury (MeHg), (199)Hg-enriched inorganic mercury (iHg), (119)Sn-enriched monobutyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) as well as homemade (116)Sn-enriched monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) was used for the isotope dilution analysis of samples. The two techniques studied were compared in terms of classic analytical parameters: linearity, precision or repeatability (i.e., percent relative standard deviation, RSD%), limit of detection (LOD), and limit of quantification (LOQ), showing excellent linearity, precision below 12% for all analytes, and LOQs of 0.06-1.45 pg for GC-MS and 0.02-0.27 pg for GC-ICP/MS.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos de Metilmercúrio/análise , Compostos Orgânicos de Estanho/análise , Ostreidae/química , Animais , Alimentos Marinhos/análise
19.
Environ Sci Pollut Res Int ; 20(3): 1292-301, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22821341

RESUMO

Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1.2 %) than in the lagoonal sediment (0.5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2.0-4.3 times higher than the endogenous one. Its methylation was just slightly higher (1.4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3.6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.


Assuntos
Sedimentos Geológicos/análise , Compostos de Mercúrio/análise , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Estuários , França , Compostos de Mercúrio/metabolismo , Isótopos de Mercúrio/análise , Metilação , Oxirredução , Espectrofotometria Atômica , Fatores de Tempo , Poluentes Químicos da Água/metabolismo
20.
Oncology ; 83(6): 321-8, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22986621

RESUMO

Concurrent chemoradiotherapy (CHRT) is the standard of care for unresectable locally advanced stage III non-small cell lung cancer. However, the optimal combination remains unclear. The aim of this study was to evaluate the efficacy of 2 induction chemotherapy cycles (days 1 and 22) with docetaxel 75 mg/m(2) and cisplatin 75 mg/m(2) followed by concurrent chemotherapy (weekly docetaxel-cisplatin, 20 mg/m(2)) and 3-D conformal radiotherapy for 6 weeks (66 Gy/5 fractions per week/2 Gy per fraction). The primary endpoint was the response rate. Secondary objectives were toxicity, time to progression, and overall survival. Forty-four patients were included and 40 were eligible. The mean age was 60.5 years (range 40.7-72.1), and 75% had stage IIIB disease. Six patients underwent complete R0 resection including 2 pathologic complete responses after a planned intermediate evaluation. Thirty-three patients completed CHRT. The objective response rate was 65% (95% CI 50.2-79.8). Grade 3-4 hematologic and digestive toxicities were observed mainly during the induction phase. Grade 3 esophagitis (5%) was experienced during CHRT. With a median follow-up of 38.7 months, the median progression-free survival was 28.3 months (95% CI 11.0-35.0) and the median survival rate was 31.4 months. Cisplatin-docetaxel induction followed by concurrent 3-D conformal radiotherapy and weekly chemotherapy is a feasible protocol associated with a promising response rate and acceptable toxicity.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/radioterapia , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/radioterapia , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Quimiorradioterapia/efeitos adversos , Quimiorradioterapia/métodos , Cisplatino/administração & dosagem , Cisplatino/efeitos adversos , Progressão da Doença , Intervalo Livre de Doença , Docetaxel , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Radioterapia Conformacional/efeitos adversos , Radioterapia Conformacional/métodos , Taxa de Sobrevida , Taxoides/administração & dosagem , Taxoides/efeitos adversos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA