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1.
Trop Anim Health Prod ; 52(6): 2883-2895, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32447584

RESUMO

Methane (CH4) emission estimations for cattle in Sub-Saharan Africa (SSA) reflect limited production levels and diets that are high in cellulose forage. However, data on these livestock systems is lacking for their accurate evaluation. To provide guidance for climate change mitigation strategies in Senegal, it is necessary to obtain reliable estimates of CH4 emissions from Ndama cattle reared in grazing systems, which is the predominant cattle system in the country. The objective of this study was to determine the annual methane emission factor (MEF) for enteric fermentation of Ndama cattle following the IPCC Tier 2 procedure. Our estimated annual MEF at the herd scale was 30.8 kg CH4/TLU (30.7 kg CH4/head/yr for lactating cows and 15.1 kg CH4/head/yr for other cattle). These values are well below the default IPCC emission factor (46 and 31 kg CH4/head/yr for dairy and other cattle, respectively) proposed in the Tier 1 method for Africa. Our study showed that feed digestibility values differ with season (from 46 to 64%). We also showed that cattle lose weight and adapt to lower feed requirements during the long dry season, with a resulting major reduction in methane emissions. The results of this work provide a new framework to re-estimate the contribution of grazing systems to methane emissions in Africa.


Assuntos
Bovinos , Fermentação , Lactação , Metano , Animais , Dieta/veterinária , Feminino , Metano/análise , Leite/química , Senegal
2.
Neuropsychol Rehabil ; 28(1): 117-141, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26732623

RESUMO

The rise of "lifelogging" in this era of rapid technological innovation has led to great interest in whether or not such technologies could be used to rehabilitate memory. Despite the growing number of studies using lifelogging, such as with wearable cameras, there is a lack of a theoretical framework to support its effective use. The present review focuses on the use of wearable cameras. We propose that wearable cameras can be particularly effective for memory rehabilitation if they can evoke more than a mere familiarity with previous stimuli, and reinstate previous thoughts, feelings and sensory information: recollection. Considering that, in memory impairment, self-initiated processes to reinstate previous encoding conditions are compromised, we invoke the environmental support hypothesis as a theoretical motivation. Twenty-five research studies were included in this review. We conclude that, despite the general acceptance of the value of wearable cameras as a memory rehabilitation technique, only a small number of studies have focused on recollection. We highlight a set of methodological issues that should be considered for future research, including sample size, control condition used, and critical measures of memory and other domains. We conclude by suggesting that research should focus on the theory-driven measure of efficacy described in this review, so that lifelogging technologies can contribute to memory rehabilitation in a meaningful and effective manner.


Assuntos
Transtornos da Memória/reabilitação , Memória Episódica , Rememoração Mental , Gravação em Vídeo , Dispositivos Eletrônicos Vestíveis , Humanos
3.
Ann Dermatol Venereol ; 144(6-7): 450-454, 2017.
Artigo em Francês | MEDLINE | ID: mdl-28396063

RESUMO

BACKGROUND: Dermal and subcutaneous inflammation following direct trauma is initially evocative of soft-tissue infection. However, two differential diagnoses must be considered: Morel-Lavallée syndrome and post-traumatic nodular fat necrosis. PATIENTS AND METHODS: Case 1: a 51-year-old woman fell off her motorbike and had dermabrasions on her right and left tibial ridges that rapidly developed into dermo-hypodermitis of the entire limb. There was no improvement after 3 weeks of antibiotics. The patient was apyretic. She had a soft, non-inflammatory tumefaction on the inner aspect of her left knee. Ultrasound revealed subcutaneous collection in both legs. The surgeons confirmed a diagnosis of Morel-Lavallée syndrome and drained the two collections. Progress was good and the patient healed without major consequences. Case 2: following a fall on her stairs, a 40-year-old woman presented dermabrasions and haematomas on her left leg. Antibiotic therapy failed to prevent the progression of dermo-hypodermitis. The patient remained apyretic and there was no inflammatory syndrome. A CT scan showed thickening of a subcutaneous fat and fluid collection, resulting in diagnosis of post-traumatic nodular fat necrosis. Management was surgical and the outcome was good. DISCUSSION: These two cases show two post-traumatic cutaneous complications: Morel-Lavallée syndrome and post-traumatic nodular fat necrosis. Morel-Lavallée syndrome occurs after tangential trauma next to richly vascularized tissue. Post-traumatic nodular fat necrosis is defined as necrosis of adipocytes. In both cases, diagnosis is confirmed by imagery (Ultrasonography, tomography). CONCLUSION: Our two case reports show that inflammatory presentation of both Morel-Lavallée syndrome and post-traumatic nodular fat necrosis can lead to diagnostic and therapeutic errors while a surgical procedure is necessary since tissue necrosis can occur.


Assuntos
Necrose Gordurosa/etiologia , Traumatismos da Perna/complicações , Tela Subcutânea/patologia , Adulto , Celulite (Flegmão)/patologia , Diagnóstico Diferencial , Drenagem/métodos , Necrose Gordurosa/diagnóstico , Necrose Gordurosa/cirurgia , Feminino , Humanos , Pessoa de Meia-Idade , Tela Subcutânea/cirurgia , Síndrome , Resultado do Tratamento
4.
Rev Neurol (Paris) ; 172(12): 735-747, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27839790

RESUMO

The emergence of life-logging technologies has led neuropsychologist to focus on understanding how this new technology could help patients with memory disorders. Despite the growing number of studies using life-logging technologies, a theoretical framework supporting its effectiveness is lacking. This review focuses on the use of life-logging in the context of memory rehabilitation, particularly the use of SenseCam, a wearable camera allowing passive image capture. In our opinion, reviewing SenseCam images can be effective for memory rehabilitation only if it provides more than an assessment of prior occurrence in ways that reinstates previous thoughts, feelings and sensory information, thus stimulating recollection. Considering the fact that, in memory impairment, self-initiated processes are impaired, we propose that the environmental support hypothesis can explain the value of SenseCam for memory retrieval. Twenty-five research studies were selected for this review and despite the general acceptance of the value of SenseCam as a memory technique, only a small number of studies focused on recollection. We discuss the usability of this tool to improve episodic memory and in particular, recollection.


Assuntos
Transtornos da Memória/reabilitação , Reabilitação/instrumentação , Doença de Alzheimer/psicologia , Doença de Alzheimer/reabilitação , Humanos , Transtornos da Memória/psicologia , Rememoração Mental
5.
Microbiology (Reading) ; 161(Pt 5): 1061-1072, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25737481

RESUMO

Purple non-sulfur bacteria are well known for their metabolic versatility. One of these bacteria, Rhodospirillum rubrum S1H, has been selected by the European Space Agency to ensure the photoheterotrophic assimilation of volatile fatty acids in its regenerative life support system, MELiSSA. Here, we combined proteomic analysis with bacterial growth analysis and enzymatic activity assays in order to better understand acetate photoassimilation. In this isocitrate lyase-lacking organism, the assimilation of two-carbon compounds cannot occur through the glyoxylate shunt, and the citramalate cycle has been proposed to fill this role, while, in Rhodobacter sphaeroides, the ethylmalonyl-CoA pathway is used for acetate assimilation. Using proteomic analysis, we were able to identify and quantify more than 1700 unique proteins, representing almost one-half of the theoretical proteome of the strain. Our data reveal that a pyruvate : ferredoxin oxidoreductase (NifJ) could be used for the direct assimilation of acetyl-CoA through pyruvate, potentially representing a new redox-balancing reaction. We additionally propose that the ethylmalonyl-CoA pathway could also be involved in acetate assimilation by the examined strain, since specific enzymes of this pathway were all upregulated and activity of crotonyl-CoA reductase/carboxylase was increased in acetate conditions. Surprisingly, we also observed marked upregulation of glutaryl-CoA dehydrogenase, which could be a component of a new pathway for acetate photoassimilation. Finally, our data suggest that citramalate could be an intermediate of the branched-chain amino acid biosynthesis pathway, which is activated during acetate assimilation, rather than a metabolite of the so-called citramalate cycle.


Assuntos
Acetatos/metabolismo , Luz , Rhodospirillum rubrum/fisiologia , Acil Coenzima A/metabolismo , Transporte Biológico , Carbono/metabolismo , Ácidos Graxos/metabolismo , Glutaril-CoA Desidrogenase/metabolismo , Malatos/metabolismo , Redes e Vias Metabólicas , Oxirredução , Proteômica
6.
J Environ Manage ; 147: 236-45, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25231026

RESUMO

Rangeland-based livestock systems have to deal with the significant instability and uncertainty of the agricultural context (policy changes, volatility of input prices, etc.), and especially of the climatic context. Thus, they are particularly concerned by adaptive management strategies. To support the development of such strategies, we developed a board game including a computer model called "Rangeland Rummy". It is to be used by groups of farmers and agricultural consultants in the context of short workshops (about 3 h). Rangeland Rummy builds upon five types of material object: (i) a game board; (ii) a calendar stick indicating the starting date of the game board; (iii) sticks marked with the feed resources available for combinations of vegetation types and their management practices; (iv) cards to define animal groups and their feeding requirements throughout the year; (v) cards related to types of feed that can be attributed to animal groups throughout the year. Using these material objects, farmers collectively design a rangeland-based livestock system. This system is immediately evaluated using a computer model, i.e. a spreadsheet providing graphs and indicators providing information on, among other things, the extent to which quantitative and qualitative animal feeding requirements are covered across the year. Playing the game thus consists in collectively and iteratively designing and evaluating rangeland-based livestock systems, while confronting the players with new contextual challenges (e.g. interannual variability of weather, volatility of input prices) or new farmers' objectives (e.g. being self-sufficient for animal feeding). An example of application of Rangeland Rummy with 3 farmers in southern France is reported. Applications show that it tends to develop farmers' adaptive capacity by stimulating their discussions and the exchange of locally-relevant knowledge on management strategies and practices in rangeland-based livestock systems.


Assuntos
Agricultura/economia , Agricultura/organização & administração , Jogos Experimentais , Gado/crescimento & desenvolvimento , Animais , Educação , França , Humanos
7.
Ann Oncol ; 24(12): 2985-9, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24013582

RESUMO

BACKGROUND: Brain metastases (BMs) pose a clinical challenge in breast cancer (BC). Lapatinib or temozolomide showed activity in BM. Our study assessed the combination of both drugs as treatment for patients with HER2-positive BC and BM. METHODS: Eighteen patients were enrolled, with sixteen of them having recurrent or progressive BM. Any type of previous therapy was allowed, and disease was assessed by gadolinium (Gd)-enhanced magnetic resonance imaging (MRI). The primary end points were the evaluation of the dose-limiting toxicities (DLTs) and the determination of the maximum-tolerated dose (MTD). The secondary end points included objective response rate, clinical benefit and duration of response. RESULTS: The lapatinib-temozolomide regimen showed a favorable toxicity profile because the MTD could not be reached. The most common adverse events (AEs) were fatigue, diarrhea and constipation. Disease stabilization was achieved in 10 out of 15 assessable patients. The estimated median survival time for the 16 patients with BM reached 10.94 months (95% CI: 1.09-20.79), whereas the median progression-free survival time was 2.60 months [95% confidence interval (CI): 1.82-3.37]. CONCLUSIONS: The lapatinib-temozolomide combination is well tolerated. Preliminary evidence of clinical activity was observed in a heavily pretreated population, as indicated by the volumetric reductions occurring in brain lesions.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias da Mama/tratamento farmacológico , Receptor ErbB-2/metabolismo , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/secundário , Neoplasias da Mama/metabolismo , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Dacarbazina/administração & dosagem , Dacarbazina/análogos & derivados , Intervalo Livre de Doença , Feminino , Humanos , Lapatinib , Dose Máxima Tolerável , Pessoa de Meia-Idade , Quinazolinas/administração & dosagem , Temozolomida , Resultado do Tratamento
8.
Br J Dermatol ; 168(1): 74-9, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22880932

RESUMO

BACKGROUND: Dermoscopy is now recognized as an essential tool for discriminating melanoma from other pigmented lesions, as corroborated by several robust meta-analyses. Although it is considered to be widely used in European countries, no published data on this topic are available to date, unlike in Australia and the U.S.A. OBJECTIVES: To describe and quantify the use and learning of dermoscopy among French private practice dermatologists. METHODS: A questionnaire of 19 items regarding demographic characteristics, dermoscopy use and training, and physician's judgment on dermoscopy was mailed to all French private practice dermatologists. Only questionnaires with an answer to the key item, 'Do you use dermoscopy?' were taken into account. RESULTS: Of 3179 mailed questionnaires, 1611 were returned and 1576 were analysable (49·6%). Most respondents declared using dermoscopy (94·6%), using their dermoscope several times a day (82·7%) and/or for the diagnosis of nonpigmented lesions (87·7%). Physicians learned dermoscopy mainly through books (75·8%) and/or conferences (88·6%); 12·8% reported a dedicated university degree. Dermoscopy helps to detect melanoma earlier and to perform fewer biopsies according to 86·6% and 74·6%, respectively. On multivariate analysis, female sex and age under 45 years were significantly associated with higher utilization rate of dermoscopy [odds ratio 1·89, 95% confidence interval (CI) 1·15-3·10; and 2·85, 95% CI 1·14-7·11, respectively]. CONCLUSIONS: This is the first published nationwide survey of dermoscopy practice in Europe. Despite potential classification and/or selection bias, the particularly high penetration rate found in our study suggests that dermoscopy is now widely accepted by French private practice dermatologists for the routine management of both pigmented and nonpigmented lesions.


Assuntos
Dermatologia/estatística & dados numéricos , Dermoscopia/estatística & dados numéricos , Padrões de Prática Médica/estatística & dados numéricos , Prática Privada/estatística & dados numéricos , Atitude do Pessoal de Saúde , Dermoscopia/educação , Feminino , França , Pesquisas sobre Atenção à Saúde , Humanos , Capacitação em Serviço , Julgamento , Masculino , Pessoa de Meia-Idade
9.
Br J Cancer ; 107(1): 1-6, 2012 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-22677904

RESUMO

BACKGROUND: Toxic death is defined as study treatment-related mortality and as such is considered as an iatrogenic death. This belongs to unnatural death where an autopsy is advised. Until now, conventional autopsy is the gold standard to discriminate between pre- and post-mortem discrepancies. METHODS: The consequences of lack of systematically performing an autopsy will be explored in the setting of oncological clinical trials. RESULTS: During more than one decade, 6428 Serious Adverse Events have been registered in the EORTC Safety database on a total of 34 734 subjects. The number of deaths were 764 (mortality rate of 2.2%) whereof 255 (rate of 0.7%) toxic deaths. In 89.8% of these toxic deaths, no autopsy has been done; in 25.1% (64 cases) an inconsistent cause of death was found based on studying of the medical narrative. The autopsy rate was only 10.2% (26 out of 255) and, in 46.2% of the performed autopsies, there was a clinical pathological discrepancy. CONCLUSION: When no autopsy is performed, there is a high risk for a wrong diagnosis in case of suspected toxic death. The high discrepancy rate, possibly due to a low autopsy rate, shows that toxic death is an Achilles' heel in iatrogenic mortality.


Assuntos
Autopsia , Ensaios Clínicos como Assunto , Neoplasias , Humanos , Causas de Morte , Erros de Diagnóstico , Neoplasias/mortalidade
10.
Transpl Infect Dis ; 14(4): 403-9, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22316326

RESUMO

Bacillary angiomatosis (BA) is a rare vasculoproliferative disorder due to Bartonella henselae (BH) or Bartonella quintana. It can involve many organs, including the skin, and has been mainly reported in patients with acquired immunodeficiency syndrome. In organ transplant recipients (OTR), this disorder remains misdiagnosed and therapeutic guidelines are nonexistent. We report 3 cases of BA with skin involvement in OTR and review similar cases from the literature. BA manifests on the skin with violaceous lesions mimicking Kaposi sarcoma, and is associated with fever, lymphadenopathy, and liver, spleen, or lung nodules. Bartonellosis infections in OTR are due to BH, the agent causing cat-scratch disease (CSD), but BA comprises histologically a prominent vascular proliferation, which is usually lacking in CSD. Cultures and serologic tests are poorly reliable for the diagnosis, which relies on demonstration of BH within the lesions. A history of cat exposure exists in most cases and pediatric OTR are at higher risk. Prevention consists of regular use of a flea-control product in cats and prompt cleaning of scratches. Our cases highlight several original features of this rare condition, which could potentially improve the management of BA in OTR.


Assuntos
Angiomatose Bacilar , Bartonella henselae , Doença da Arranhadura de Gato , Transplante de Rim/efeitos adversos , Angiomatose Bacilar/diagnóstico , Angiomatose Bacilar/microbiologia , Angiomatose Bacilar/patologia , Animais , Doença da Arranhadura de Gato/diagnóstico , Doença da Arranhadura de Gato/microbiologia , Doença da Arranhadura de Gato/patologia , Gatos , Criança , Humanos , Masculino , Pessoa de Meia-Idade , Dermatopatias Bacterianas/diagnóstico , Dermatopatias Bacterianas/microbiologia , Dermatopatias Bacterianas/patologia
11.
J Phys Chem A ; 116(34): 8678-83, 2012 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-22857603

RESUMO

The mechanism of photomagnetism in copper octacyanomolybdate molecules is currently under debate. Contrary to the general belief that the photomagnetic transition occurs only due to a photoinduced electron transfer from the molybdenum to the copper atom, recent X-ray magnetic dichroic (XMCD) data clearly indicate that this phenomenon is associated at low temperature to a local low-spin-high-spin transition on the molybdenum atom. In this article we provide theoretical justification for these experimental facts. We show the first simulation of X-ray absorption (XAS) and magnetic circular dichroism (XMCD) spectra at the L(2,3) edges of molybdenum from the joint perspective of density functional theory (DFT) calculations and ligand field multiplet (LFM) theory. The description of electronic interactions seems mandatory for reproducing the photomagnetic state.

12.
Appl Ergon ; 95: 103427, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33895470

RESUMO

This study adapted the Demand Resource Evaluation Scores (DRES) as a metacognitive indicator in assessing pilot students' perceptions during simulated training of a novel maneuver. Typically, positive DRES are associated with perceiving a demanding situation as a challenge and with improved performance, while negative DRES are linked to a perception of the situation as a threat, and to poorer performance. The novelty here was to assess DRES before and after the task and across three missions. Overall, students were found to change their perceptions from threat to challenge over time. Also, increased DRES were positively correlated with performance progressing from mission to mission, indicating that the students reflect on their performance as they advance in their training. These findings show that individual metacognitive evaluations of a stressful aviation maneuver might be important for the progress in performance. The results are discussed in terms of flight safety and pilot training.


Assuntos
Aviação , Metacognição , Pilotos , Treinamento por Simulação , Humanos , Estudantes
13.
Clin Exp Dermatol ; 34(8): e851-3, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19843081

RESUMO

Eosinophilic fasciitis (EF) is a connective-tissue disease characterized by thickened fascia. Involvement of the dermis may occur during the progression of the disease, characterized clinically by morphoea-like plaques (MLPs). This more superficial feature of EF carries a poor prognosis, suggestive of refractory EF that requires intensive therapy. We report a case in which morphoea-like plaques occurred before the EF. This case and previous cases of MLPs show some differences between MLPs and classic morphoea. Clinically, MLPs present with ill-defined brown plaques, with no lilac ring or ivory colour. Histologically, there is a more marked inflammatory infiltrate and an increase in the number of eosinophils. The discovery of MLPs at an early stage should prompt examination of the fascia with magnetic resonance imaging or surgical biopsy, and aggressive treatment.


Assuntos
Eosinofilia/patologia , Fasciite/patologia , Esclerodermia Localizada/patologia , Idoso , Feminino , Humanos
16.
Case Rep Hematol ; 2019: 7609308, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31534805

RESUMO

Here, we describe a rare case of acquired von Willebrand syndrome (VWS) associated with intracranial plasmacytoma. The literature includes reports of a few cases of plasmacytoma with central nervous involvement, but none of them with acquired VWS. Diagnosis was made based on a stereotaxic intracerebral biopsy. During this biopsy, a ventriculoperitoneal shunt was established, which was complicated with abnormal bleeding. Subsequent hemostasis assessment related to hemopathy revealed acquired von Willebrand disease. The patient received induction therapy with bortezomib, thalidomide, and dexamethasone (VTD), followed by high-dose melphalan chemotherapy and autologous stem cell transplantation, and then VTD consolidation, and finally maintenance with lenalidomide. Our patient currently remains in very good partial response without neurological symptoms after 4 months of maintenance. The patient is free of progression 14 months after their original presentation.

17.
Radiat Prot Dosimetry ; 127(1-4): 97-102, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17578878

RESUMO

Radionuclides may be released into the environment accidentally or incidentally, which could raise health risks when ingested or inhaled by humans. In order to study the behaviour of radionuclides in the human organism (metabolism, retention, excretion), knowledge of radionuclide speciation is indispensable: speciation governs the transfer, bioavailability and toxicity of elements and is also of considerable interest for decorporation. In this context, the Commissariat à l'Energie Atomique has created a working group on speciation to share data both on thermodynamic constants and on speciation analysis methods of interest to chemists, environmentalists and biologists. The initial focus was on the 31 radionuclides described in different International Commission on Radiological Protection models (HRTM, HAT) and the National Council on Radiation Protection model (wound). Particular attention was devoted to selecting the inorganic and organic ligands, most representative of biological media. The base applied to speciation in solution and at interfaces and solubility (BASSIST) thermodynamic database was developed for this purpose. The aim of this paper is to present the state of the art on radionuclide speciation tools within biological media and to emphasise some missing data in order to orient future research.


Assuntos
Corpos Estranhos/fisiopatologia , Modelos Biológicos , Plutônio/farmacocinética , Plutônio/toxicidade , Radiometria/métodos , Radiometria/tendências , Ferimentos Penetrantes/fisiopatologia , Carga Corporal (Radioterapia) , Simulação por Computador , Previsões , Corpos Estranhos/complicações , Humanos , Injeções/efeitos adversos , Cinética , Taxa de Depuração Metabólica , Lesões por Radiação/etiologia , Lesões por Radiação/fisiopatologia , Eficiência Biológica Relativa , Ferimentos Penetrantes/etiologia
18.
Case Rep Hematol ; 2017: 9423205, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28197347

RESUMO

We describe a rare case of Castleman disease associated de novo with Hodgkin lymphoma. The incidence of Castleman disease is rare; only a few studies have described it in de novo association with Hodgkin lymphoma. The patient described here complained of unique evolutionary axillary adenopathy. A positron-emission tomography/computed tomography scan revealed hypermetabolic activity in this area. Diagnosis was based on a total excision biopsy of the adenopathy. The patient underwent complete remission with ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) chemotherapy for treating Hodgkin lymphoma after surgical excision of the unicentric Castleman disease lesion.

19.
J Environ Radioact ; 178-179: 343-348, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28947086

RESUMO

Uranium is naturally present in seawater at trace levels and may in some cases be present at higher concentrations, due to anthropogenic nuclear activities. Understanding uranium speciation in seawater is thus essential for predicting and controlling its behavior in this specific environmental compartment and consequently, its possible impact on living organisms. The carbonato calcic complex Ca2UO2(CO3)3 was previously identified as the main uranium species in natural seawater, together with CaUO2(CO3)32-. In this work, we further investigate the role of the alkaline earth cation in the structure of the ternary uranyl-carbonate complexes. For this purpose, artificial seawater, free of Mg2+ and Ca2+, using Sr2+ as a spectroscopic probe was prepared. Combining TRLIF and EXAFS spectroscopy, together with DFT and theoretical thermodynamic calculations, evidence for the presence of Sr alkaline earth counter ion in the complex structure can be asserted. Furthermore, data suggest that when Ca2+ is replaced by Sr2+, SrUO2(CO3)32- is the main complex in solution and it occurs with the presence of at least one monodentate carbonate in the uranyl coordination sphere.


Assuntos
Carbonatos/análise , Modelos Químicos , Água do Mar/química , Urânio/análise , Adsorção
20.
Biochimie ; 88(11): 1591-604, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17064836

RESUMO

Mineral elements, often at the trace level, play a considerable role in physiology and pathology of biological systems. Metallogenomics, metalloproteomics, and metallomics are among the emerging disciplines which are critically dependent on spatially resolved concentration maps of trace elements in a cell or tissue, on information on chemical speciation, and on that on metal-binding coordination sites. The mini-review discusses recent progress in analytical techniques for element profiling on the genome scale, biological trace element imaging, and probing, identification and quantification of chemical species in the biological environment. Imaging of the element distribution in cells and tissue sections is becoming possible with sub-micrometer spatial resolution and picogram-level sensitivity owing to advances in laser ablation MS, ion beam and synchrotron radiation X-ray fluorescence microprobes. Progress in nanoflow chromatography and capillary electrophoresis coupled with element specific ICP MS and molecule-specific electrospray MS/MS and MALDI enables speciation of elements in microsamples in a complex biological environment. Laser ablation ICP MS, micro-SXRF, and micro-PIXE allow mapping of trace element distribution in 1D and 2D proteomics gels. The increasing sensitivity of EXAFS and XANES owing to the use of more intense synchrotron beams and efficient focusing optics provide information about oxidation state, fingerprint speciation of metal sites and metal-site structures.


Assuntos
Poluição Ambiental , Oligoelementos/análise , Alimentos , Espectroscopia de Ressonância Magnética , Proteoma , Sensibilidade e Especificidade , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
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