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1.
J Am Soc Mass Spectrom ; 30(2): 248-255, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30414066

RESUMO

Steroids represent an interesting class of small biomolecules due to their use as biomarkers and their status as scheduled drugs. Although the analysis of steroids is complicated by the potential for many isomers, ion mobility spectrometry (IMS) has previously shown promise for the rapid separation of steroid isomers. This work is aimed at the further development of IMS separation for the analysis of steroids. Here, traveling wave ion mobility spectrometry (TWIMS) was applied to the study of group I metal adducted steroids and their corresponding multimers for five sets of isomers. Each set of isomers had a minimum of one dimeric metal ion adduct that exhibited a resolution greater than one (i.e., approaching baseline resolution). Additionally, ion-neutral collision cross sections (CCSs) were measured using polyalanine as a calibrant, which may provide an additional metric contributing to analyte identification. Where possible, measured CCSs were compared to previously reported values. When measuring CCSs of steroid isomers using polyalanine as the calibrant, nitrogen CCS values were within 1.0% error for monomeric sodiated adducts and slightly higher for the dimeric sodiated adducts. Overall, TWIMS was found to successfully separate steroids as dimeric adducts of group I metals. Graphical Abstract ᅟ.


Assuntos
Espectrometria de Mobilidade Iônica/métodos , Metais Leves/química , Metais/química , Esteroides/isolamento & purificação , Calibragem , Isomerismo , Nitrogênio/análise , Peptídeos/química , Peptídeos/isolamento & purificação , Esteroides/química
2.
Acta Pharmacol Sin ; 39(11): 1760-1767, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29891857

RESUMO

Bone loss induced by microgravity is a substantial barrier to humans in long-term spaceflight. Recent studies have revealed that icariin (ICA) can attenuate osteoporosis in postmenopausal women and ovariectomized rats. However, whether ICA can protect against microgravity-induced bone loss remains unknown. In this study, the effects of ICA on a hindlimb suspension rodent model were investigated. Two-month-old female Wistar rats were hindlimb suspended and treated with ICA (25 mg·kg-1·d-1, i.g.) or a vehicle for 4 weeks (n = 6). The bone mass density of the hindlimbs was analyzed using dual-energy X-ray absorptiometry and micro-CT. mRNA expression of osteogenic genes in the tibia and the content of bone metabolism markers in serum were measured using qRT-PCR and ELISA, respectively. The bone mineral phase was analyzed using X-ray diffraction and atomic spectrometry. The results showed that ICA treatment significantly rescued the hindlimb suspension-induced reduction in bone mineral density, trabecular number and thickness, as well as the increases in trabecular separation and the structure model index. In addition, ICA treatment recovered the decreased bone-related gene expression, including alkaline phosphatase (ALP), bone glaprotein (BGP), and osteoprotegerin/receptor activator of the NF-κB ligand ratio (OPG/RANKL), in the tibia and the decreased bone resorption marker TRACP-5b levels in serum caused by simulated microgravity. Notably, ICA treatment restored the instability of bone biological apatite and the metabolic disorder of bone mineral elicited by simulated microgravity. These results demonstrate that ICA treatment plays osteoprotective roles in bone loss induced by simulated microgravity by inhibiting bone resorption and stabilizing bone biological apatite.


Assuntos
Apatitas/metabolismo , Conservadores da Densidade Óssea/uso terapêutico , Reabsorção Óssea/prevenção & controle , Flavonoides/uso terapêutico , Animais , Densidade Óssea/efeitos dos fármacos , Feminino , Fêmur/efeitos dos fármacos , Elevação dos Membros Posteriores , Metais Leves/metabolismo , Ratos Wistar
3.
Artigo em Inglês | MEDLINE | ID: mdl-29890707

RESUMO

Concentrations and spatial variations of the four cations Na, K, Mg and Ca are known to some extent for groundwater and to a lesser extent for drinking water. Using Denmark as case, the purpose of this study was to analyze the spatial and temporal variations in the major cations in drinking water. The results will contribute to a better exposure estimation in future studies of the association between cations and diseases. Spatial and temporal variations and the association with aquifer types, were analyzed with spatial scan statistics, linear regression and a multilevel mixed-effects linear regression model. About 65,000 water samples of each cation (1980⁻2017) were included in the study. Results of mean concentrations were 31.4 mg/L, 3.5 mg/L, 12.1 mg/L and 84.5 mg/L for 1980⁻2017 for Na, K, Mg and Ca, respectively. An expected west-east trend in concentrations were confirmed, mainly explained by variations in aquifer types. The trend in concentration was stable for about 31⁻45% of the public water supply areas. It is therefore recommended that the exposure estimate in future health related studies not only be based on a single mean value, but that temporal and spatial variations should also be included.


Assuntos
Água Potável/química , Exposição Ambiental/estatística & dados numéricos , Metais Alcalinoterrosos/análise , Metais Leves/análise , Saúde Pública , Poluentes Químicos da Água/análise , Cátions , Dinamarca , Água Potável/análise , Exposição Ambiental/análise , Monitoramento Ambiental/métodos , Humanos , Modelos Lineares , Análise Espaço-Temporal
4.
Environ Sci Pollut Res Int ; 25(13): 12444-12450, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29460250

RESUMO

Arctic-alpine tundra habitats are very vulnerable to the input of relatively small amounts of xenobiotics, and thus their level in such areas must be carefully controlled. Therefore, we collected the terrestrial widespread moss Racomitrium lanuginosum (Hedw.) Brid. in Spitsbergen in the Arctic moss lichen tundra and, for comparison, in the Arctic-alpine tundra in the Karkonosze (SW Poland). Concentrations of the elements Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Na, Ni, Pb, V, and Zn in this species and in the parent rock material were measured. We tested the following hypothesis: R. lanuginosum from Spitsbergen contains lower metal levels than the species from the Karkonosze collected at altitudes influenced by long-range transport from former Black Triangle industry. Principal component and classification analysis (PCCA) ordination revealed that mosses of Spitsbergen were distinguished by a significantly higher Na concentration of marine spray origin and mosses of Karkonosze were distinguished by significantly higher concentrations of Cd, Cr, Cu, Fe, Hg, Li, Mn, Pb, V, and Zn probably from long-range atmospheric transport. The influence of the polar station with a waste incinerator resulted in significantly higher Co, Li, and Ni concentrations in neighbouring mosses in comparison with this species from other sites. This investigation contributes to the use of R. lanuginosum as a bioindicator for metal contamination in Arctic and alpine tundra regions characterised by severe climate habitats with a restricted number of species. This moss enables the control of pollution usually brought solely by long-range atmospheric transport in high mountains as well as in Arctic areas.


Assuntos
Poluentes Atmosféricos/metabolismo , Bryopsida/metabolismo , Monitoramento Ambiental , Metais Pesados/metabolismo , Metais Leves/metabolismo , Poluentes do Solo/metabolismo , Geografia , Polônia , Svalbard , Tundra
5.
Environ Sci Pollut Res Int ; 25(4): 3823-3839, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29178000

RESUMO

The Po Valley is one of the most important hot spots in Europe for air pollution. Morphological features and anthropogenic pressures lead to frequent breaching of air quality standards and to high-pollution episodes in an ~46 × 103-km2-wide alluvial lowland. Therefore, it is increasingly important to study the air quality in a wide geographical scale to better implement possible and successful mitigation measures. The Veneto region lies in the eastern part of the Po Valley and the elemental composition of PM has been mainly studied in the Venice area, whereas scarce data are available for the remaining territory of the region. In this study, the elemental composition of PM2.5 was investigated over 1 year (2012-2013) at six major cities of the Veneto region. Samples were analyzed for 16 elements (Ca, Al, Fe, S, K, Mg, Ti, Mn, Zn, Ba, As, Ni, Pb, Sb, V, and Cu), and results were processed to investigate spatial and seasonal variations, the influence of meteorological factors, and the most probable sources by using a procedure based on (i) elemental ratios (Cu/Sb, Cu/Zn, Cu/Pb, Mn/V, V/Ni, and Zn/Pb), (ii) cluster analysis on wind data, and (iii) conditional probability function (CPF). The percentage of elements in PM2.5 ranged between 11 and 20%, and Ca and S were the most abundant elements in the region. Typical seasonal variations and similar trends were exhibited by each element, especially in the lowland. Some elements such as Zn, K, Mn, Pb, and Sb were found at high concentrations during the cold period. However, no similar dispersion processes were observed throughout the region, and their concentrations were mostly depending on individual local sources. In the alpine and foothill parts of the region, lower concentrations were recorded with respect to the Po Valley cities, which resulted enriched of most of the elements considered in this study. The cluster analysis on wind data and the CPF of the ratio-related sources demonstrated that a widespread pollution condition exists in the region, apart from the coastal area. However, specific directions (e.g., a link with high-traffic roads, industrial areas, and airports) resulted the most probable explanation for each ratio-related source. In addition, the Veneto region hosts one of the most important Mediterranean ports for the cruise sector (Venice harbor), and its impact was previously demonstrated in the historical city center. In this study, the impact of Venice shipping emissions was estimated to be 3.5% of PM2.5 in some particular days.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Metais Pesados/análise , Metais Leves/análise , Material Particulado/química , Cidades , Análise por Conglomerados , Itália , Limite de Detecção , Estações do Ano , Enxofre/análise , Vento
6.
Nucleic Acids Res ; 46(D1): D459-D464, 2018 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-29077942

RESUMO

MetalPDB (http://metalweb.cerm.unifi.it/) is a database providing information on metal-binding sites detected in the three-dimensional (3D) structures of biological macromolecules. MetalPDB represents such sites as 3D templates, called Minimal Functional Sites (MFSs), which describe the local environment around the metal(s) independently of the larger context of the macromolecular structure. The 2018 update of MetalPDB includes new contents and tools. A major extension is the inclusion of proteins whose structures do not contain metal ions although their sequences potentially contain a known MFS. In addition, MetalPDB now provides extensive statistical analyses addressing several aspects of general metal usage within the PDB, across protein families and in catalysis. Users can also query MetalPDB to extract statistical information on structural aspects associated with individual metals, such as preferred coordination geometries or aminoacidic environment. A further major improvement is the functional annotation of MFSs; the annotation is manually performed via a password-protected annotator interface. At present, ∼50% of all MFSs have such a functional annotation. Other noteworthy improvements are bulk query functionality, through the upload of a list of PDB identifiers, and ftp access to MetalPDB contents, allowing users to carry out in-depth analyses on their own computational infrastructure.


Assuntos
Bases de Dados de Proteínas , Substâncias Macromoleculares/química , Metaloproteínas/química , Metais Pesados/química , Metais Leves/química , Interface Usuário-Computador , Sequência de Aminoácidos , Biocatálise , Cátions Bivalentes , Cátions Monovalentes , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Humanos , Internet , Substâncias Macromoleculares/metabolismo , Metaloproteínas/metabolismo , Metais Pesados/metabolismo , Metais Leves/metabolismo , Conformação Molecular , Anotação de Sequência Molecular
7.
Turk J Med Sci ; 47(1): 246-251, 2017 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-28263497

RESUMO

BACKGROUND/AIM: This study was undertaken to determine the changes and relationships between some important milk constituents as well as physical, rheological, and biochemical parameters of milk obtained from Serbian breastfeeding mothers. MATERIALS AND METHODS: Physicochemical and biochemical parameters and the concentrations of vitamins, uric acid, and minerals were determined during the three periods of lactation covering colostrum, transitional, and mature milk collected from 67 mothers who had a term-pregnancy. RESULTS: Large interindividual variations regarding many parameters were found between mothers at the same period of lactation, but the average values were mostly in the expected and recommended ranges. For some parameters, our values are quite different in relation to the milk of women from other countries or data reported by other authors. CONCLUSION: Differences in vitamin and mineral contents and physicochemical and rheological characteristics of milk obtained by Serbian breastfeeding mothers compared to that of mothers from other parts of the world have been found. This paper presents the measured data of some physical parameters of human milk about which there is little information in the literature.


Assuntos
Aleitamento Materno/etnologia , Leite Humano/química , Leite Humano/fisiologia , Adulto , Cálcio/análise , Fenômenos Químicos , Feminino , Humanos , Metais Leves/análise , Sérvia/etnologia , Ácido Úrico/análise , Vitaminas/análise
8.
J Phys Chem B ; 121(4): 787-799, 2017 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-28002946

RESUMO

Phosphatidylserine (PS) and phosphatidylcholine (PC) are two of the major anionic and zwitterionic phospholipids in mammalian cell membranes. Ion-PS interaction is hypothesized to play a crucial role in a range of biological events including membrane fusion, lipid phase modulation, membrane protein insertion and translocation. In this study, we characterize lipid nanodomain formation in PC/PS mixed bilayers using coarse-grained simulations. We investigate the role of monovalent cation sizes in modulating lipid-ion binding modes and lipid demixing. Our simulations suggest that certain lipid-ion binding modes lead to growth of ion-mediated PS lipid clusters. The existing literature reveals the polymorphism in binding and partitioning patterns in monovalent cations (Na+, K+, and Li+) with anionic lipids. Our work provides a microscopic view on the ion-size-dependent PS lipid packing pattern observed experimentally. A coupled relationship between lipid curvature and asymmetry is observed in highly demixed PC/PS mixed bilayers.


Assuntos
Bicamadas Lipídicas/química , Metais Leves/química , Nanopartículas/química , Fosfatidilcolinas/química , Fosfatidilserinas/química , Fosfolipídeos/química , Ânions/química , Cátions/química
9.
Environ Sci Pollut Res Int ; 23(20): 20772-20782, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27475436

RESUMO

The South-to-North Water Diversion Project has aroused widespread concerns about the potential ecological risks posed by the project, especially for the Miyun Reservoir (MYR). The potential release risk of metals from the flooded riparian soils into MYR after water impoundment is one of key scientific problems. In this study, riparian soil samples were collected considering three vertical heights (130, 140, and 145 m) and four types of land uses in the MYR areas, namely, forestland, grassland, wasteland, and recreational land. We analyzed soils texture, the content and chemical fractionations of seldom monitored trace elements (SMTEs): Li, Be, B, V, Co, Ni, Ga, Sn, Sb, Tl, and Bi). Results showed that the four types of soils in MYR had the similar textures, while recreational land showed significantly higher contents of Ni and V. Additionally, there were no significant differences found for most SMTEs (except for V) at different vertical heights in each soil type, while the concentrations of V at 140 and 145 m in forestland and recreational land were significantly higher than those at 130 m. However, a comprehensive evaluation of potential ecological risk (contamination factor (CF), modified degree of contamination (mCd), and geoaccumulation factor (I geo)) consistently indicated the insignificant contaminations of all SMTEs in MYR soils before water impoundment. The Community Bureau of Reference (BCR) sequential extraction results showed that the chemical fractionations of SMTEs were independent of land use patterns and vertical heights. Co in reducible fractions and Ni were identified as the candidates which had potential to release into MYR when the lands were submerged. Principal component analysis (PCA) and cluster analysis (CA) results suggested that a portion of V, Co, and Ni may originate from anthropogenic activities, and the coal combustion was possibly the main anthropogenic source. The findings of this work would provide valuable information on the environment management of MYR and offer a reference for the investigation on the effect of water impoundment on potential release risk of SMTEs in MYR.


Assuntos
Monitoramento Ambiental/métodos , Poluentes do Solo/análise , Solo/química , Oligoelementos/análise , Recursos Hídricos , Fracionamento Químico , China , Inundações , Metais Pesados/análise , Metais Leves/análise
10.
Chem Rev ; 116(14): 8173-92, 2016 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-27398715

RESUMO

We begin with a brief historical review of the development of our understanding of the normal ordering of nd orbitals of a transition metal interacting with ligands, the most common cases being three below two in an octahedral environment, two below three in tetrahedral coordination, and four below one in a square-planar environment. From the molecular orbital construction of these ligand field splittings evolves a strategy for inverting the normal order: the obvious way to achieve this is to raise the ligand levels above the metal d's; that is, make the ligands better Lewis bases. However, things are not so simple, for such metal/ligand level placement may lead to redox processes. For 18-electron octahedral complexes one can create the inverted situation, but it manifests itself in the makeup of valence orbitals (are they mainly on metal or ligands?) rather than energy. One can also see the effect, in small ways, in tetrahedral Zn(II) complexes. We construct several examples of inverted ligand field systems with a hypothetical but not unrealistic AlCH3 ligand and sketch the consequences of inversion on reactivity. Special attention is paid to the square-planar case, exemplified by [Cu(CF3)4](-), in which Snyder had the foresight to see a case of an inverted field, with the empty valence orbital being primarily ligand centered, the dx2-y2 orbital heavily occupied, in what would normally be called a Cu(III) complex. For [Cu(CF3)4](-) we provide theoretical evidence from electron distributions, geometry of the ligands, thermochemistry of molecule formation, and the energetics of abstraction of a CF3 ligand by a base, all consistent with oxidation of the ligands in this molecule. In [Cu(CF3)4](-), and perhaps more complexes on the right side of the transition series than one has imagined, some ligands are σ-noninnocent. Exploration of inverted ligand fields helps us see the continuous, borderless transition from transition metal to main group bonding. We also give voice to a friendly disagreement on oxidation states in these remarkable molecules.


Assuntos
Complexos de Coordenação/química , Modelos Químicos , Materiais Biomiméticos/química , Bases de Lewis/química , Ligantes , Metais Pesados/química , Metais Leves/química , Estrutura Molecular , Oxirredução , Teoria Quântica
11.
Int J Legal Med ; 130(1): 281-6, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26493693

RESUMO

An examination of the chemistry of adipocere formation in aquatic systems provides insight into how environmental factors affect the decomposition processes of human remains. Gas chromatography­mass spectrometry (GC-MS) and inductively coupled plasma­mass spectrometry (ICPMS) have been employed to monitor the changes to the chemistry of adipocere formed in aquatic environments used to model seawater, river and chlorinated water systems. Seawater was shown to inhibit adipocere formation, and a distinctively different elemental composition was produced in this environment due to the high concentrations of salts. By comparison, river water has been shown to accelerate the formation of adipocere. Chlorinated water appears to significantly enhance adipocere formation, based on a comparison with established fatty acid concentration values. However, a competing reaction to form chlorohydrins in chlorinated water is believed to be responsible for the unusual findings in this environment. The application of the chemical characterization of adipocere to an understanding of how this particular decomposition product forms in different water environments has been demonstrated, and there is potential to utilise this approach to identify the environment in which a body has been immersed.


Assuntos
Imersão , Mudanças Depois da Morte , Animais , Cálcio/análise , Ácidos Graxos/análise , Patologia Legal , Cromatografia Gasosa-Espectrometria de Massas , Metais Leves/análise , Modelos Animais , Rios , Água do Mar , Extração em Fase Sólida , Suínos
12.
Artigo em Inglês | MEDLINE | ID: mdl-26125226

RESUMO

Toxic and nutrient elements were investigated in yerba mate (Ilex paraguariensis) from South America. Fifty-four brands of commercialised yerba mate from Argentina, Brazil, Paraguay and Uruguay were analysed for Al, Ba, Ca, Cu, Fe, K, Mg, Mn, P, Sr, and Zn, using inductively coupled plasma optical emission spectrometry (ICP-OES), and Li, Be, Ti, V, Cr, Ni, Co, As, Se, Rb, Mo, Ag, Cd, Sb, La, Ce, Pb, Bi and U using inductively coupled plasma mass spectrometry (ICP-MS). Antimony, Se, Ag and Bi were not detected in any sample whereas the limits of detection (LODs) of these elements were 0.19, 0.40, 0.003 and 0.001 µg g(-1), respectively. Analysis of variance (ANOVA) revealed that the concentrations of Cd, Ti, Ni, As, Mo, U, Li and Be in yerba mate were not statistically different with regard to the country of origin, while those of the other investigated elements differed.


Assuntos
Bebidas/análise , Contaminação de Alimentos , Ilex paraguariensis/química , Metais Pesados/análise , Folhas de Planta/química , Caules de Planta/química , Oligoelementos/análise , Métodos Analíticos de Preparação de Amostras , Arsênico/análise , Arsênico/toxicidade , Bebidas/efeitos adversos , Bebidas/economia , Cálcio na Dieta/análise , Inspeção de Alimentos , Humanos , Limite de Detecção , Espectrometria de Massas , Metais Pesados/toxicidade , Metais Leves/análise , Metais Leves/toxicidade , Valor Nutritivo , Reprodutibilidade dos Testes , América do Sul , Espectrofotometria Atômica
13.
Talanta ; 132: 591-9, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25476349

RESUMO

The article presents the optimisation, validation and application of the microwave induced plasma optical emission spectrometry (MIP-OES) dedicated for a routine determination of Ag, Al, B, Ba, Bi, Ca, Cd, Cr, Cu, Fe, Ga, In, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sr, Tl, Zn, in the geological samples. The three procedures of sample preparation has been proposed: sample digestion with the use of hydrofluoric acid for determination of total concentration of elements, extraction by aqua regia for determination of the quasi-total element concentration and extraction by hydrochloric acid solution to determine contents of the elements in acid leachable fraction. The detection limits were on the level 0.001-0.121 mg L(-1) (from 0.010-0.10 to 1.2-12 mg kg(-1) depend on the samples preparation procedure); the precision: 0.20-1.37%; accuracy 85-115% (for recovery for certified standards materials analysis and parallel analysis by independent analytical techniques: X-ray fluorescence (XRF) and flame absorption spectrometry (FAAS)). The conformity of the results obtained by MIP-OES analytical procedures with the results obtained by XRF and FAAS analysis allows to propose the procedures for studies of elemental composition of the fraction of the geological samples. Additionally, the MIP-OES technique is much less expensive than ICP techniques and much less time-consuming than AAS techniques.


Assuntos
Espectrometria de Massas/métodos , Metais Alcalinos/análise , Metais Alcalinoterrosos/análise , Metais Pesados/análise , Metais Leves/análise , Metais Terras Raras/análise , Sedimentos Geológicos/química , Geologia/instrumentação , Geologia/métodos , Ácido Clorídrico/química , Limite de Detecção , Espectrometria de Massas/instrumentação , Micro-Ondas , Gases em Plasma , Extração em Fase Sólida/métodos
14.
Biomed Khim ; 60(3): 378-88, 2014.
Artigo em Russo | MEDLINE | ID: mdl-25019401

RESUMO

Methods of whole blood trace element determination by Graphite furnace atomic absorption spectrometry (in the variant of Zeeman's modulation polarization spectrometry) have been proposed. They do not require preliminary sample digestion. Furnace programs, modifiers and blood dilution factors were optimized. Seronorm™ human whole blood reference materials were used for validation. Dynamic ranges (for undiluted blood samples) were: Al 8 ¸ 210 мg/L; Be 0.3 ¸ 50 мg/L; Cd 0.2 ¸ 75 мg/L; Сo 5 ¸ 350 мg/L; Cr 10 ¸ 100 мg/L; Mn 6 ¸ 250 мg/L; Ni 10 ¸ 350 мg/L; Pb 3 ¸ 240 мg/L; Se 10 ¸ 500 мg/L; Tl 2 ¸ 600 мg/L. Precision (RSD) for the middle of dynamic range ranged from 5% for Mn to 11 for Se.


Assuntos
Calcogênios/sangue , Metais Pesados/sangue , Metais Leves/sangue , Espectrofotometria Atômica/métodos , Humanos , Padrões de Referência , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Atômica/instrumentação
15.
J Environ Radioact ; 136: 131-9, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24953228

RESUMO

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a ∪-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved.


Assuntos
Arqueologia/métodos , Fósseis , Modelos Teóricos , Paleontologia/métodos , Tíbia/química , Urânio/química , Adsorção , Animais , Cálcio/química , Difusão , Mamíferos , Metais Leves/química , Análise de Ativação de Nêutrons , Espectrometria gama , Urânio/análise
16.
Anal Chem ; 86(10): 5108-15, 2014 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-24734900

RESUMO

We report a method that allows a complete quantitative characterization of whole single cells, assessing the total amount of carbon, nitrogen, oxygen, sodium, and magnesium and providing submicrometer maps of element molar concentration, cell density, mass, and volume. This approach allows quantifying elements down to 10(6) atoms/µm(3). This result was obtained by applying a multimodal fusion approach that combines synchrotron radiation microscopy techniques with off-line atomic force microscopy. The method proposed permits us to find the element concentration in addition to the mass fraction and provides a deeper and more complete knowledge of cell composition. We performed measurements on LoVo human colon cancer cells sensitive (LoVo-S) and resistant (LoVo-R) to doxorubicin. The comparison of LoVo-S and LoVo-R revealed different patterns in the maps of Mg concentration with higher values within the nucleus in LoVo-R and in the perinuclear region in LoVo-S cells. This feature was not so evident for the other elements, suggesting that Mg compartmentalization could be a significant trait of the drug-resistant cells.


Assuntos
Células/química , Elementos , Metais Leves/química , Linhagem Celular Tumoral , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Células/metabolismo , Resistencia a Medicamentos Antineoplásicos , Humanos , Processamento de Imagem Assistida por Computador , Metais Leves/metabolismo , Microscopia de Força Atômica
17.
J Enzyme Inhib Med Chem ; 29(6): 773-6, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24506207

RESUMO

Abstract Carbonic anhydrase was purified and characterized from erythrocytes of the Turkish native chicken, Gerze, for the first time. The enzyme was purified 57.65-fold with a yield of 52%, and a specific activity of 954.08 U/mg proteins having optimum pH at 8.0; optimum temperature at 30 °C; optimum ionic strength at 10 mM and stable pH at 8.0. The purified enzyme had apparent KM and Vmax values of 0.73 mM and 0.236 µmol × min(-1), respectively. Al(+3), Hg(+2), Cu(+2), Pb(+2), and Cd(+2) showed inhibitory effects on the enzyme. Pb(+2) exhibited the strongest inhibitory action. Cd(+2) and Hg(+2) were moderate inhibitor, whereas Al(+3) and Cu(+2) showed weaker actions. All tested metals inhibited the enzyme in competitive manner. Our findings indicate that these metals inhibit the chicken enzyme in a similar manner to other α-CAs from mammals investigated earlier, but susceptibility to various metals differ between the native chicken and other mammalian enzymes.


Assuntos
Inibidores da Anidrase Carbônica/química , Anidrases Carbônicas/química , Galinhas/metabolismo , Eritrócitos/enzimologia , Metais Pesados/química , Metais Leves/química , Alumínio/química , Animais , Cádmio/química , Anidrases Carbônicas/isolamento & purificação , Cátions , Cobre/química , Espécies em Perigo de Extinção , Eritrócitos/química , Concentração de Íons de Hidrogênio , Cinética , Chumbo/química , Mercúrio/química , Concentração Osmolar , Turquia
18.
Artigo em Inglês | MEDLINE | ID: mdl-24405320

RESUMO

The FACET tool is a probabilistic model to estimate exposure to chemicals in foodstuffs, originating from flavours, additives and food contact materials. This paper demonstrates the use of the FACET tool to estimate exposure to BPA (bisphenol A) from light metal packaging. For exposure to migrants from food packaging, FACET uses industry-supplied data on the occurrence of substances in the packaging, their concentrations and construction of the packaging, which were combined with data from a market research organisation and food consumption data supplied by national database managers. To illustrate the principles, UK packaging data were used together with consumption data from the UK National Diet and Nutrition Survey (NDNS) dietary survey for 19-64 year olds for a refined deterministic verification. The UK data were chosen mainly because the consumption surveys are detailed, data for UK packaging at a detailed level were available and, arguably, the UK population is composed of high consumers of packaged foodstuffs. Exposures were run for each food category that could give rise to BPA from light metal packaging. Consumer loyalty to a particular type of packaging, commonly referred to as packaging loyalty, was set. The BPA extraction levels used for the 15 types of coating chemistries that could release BPA were in the range of 0.00005-0.012 mg dm(-2). The estimates of exposure to BPA using FACET for the total diet were 0.0098 (mean) and 0.0466 (97.5th percentile) mg/person/day, corresponding to 0.00013 (mean) and 0.00059 (97.5th percentile) mg kg(-1) body weight day(-1) for consumers of foods packed in light metal packaging. This is well below the current EFSA (and other recognised bodies) TDI of 0.05 mg kg(-1) body weight day(-1). These probabilistic estimates were compared with estimates using a refined deterministic approach drawing on the same input data. The results from FACET for the mean, 95th and 97.5th percentile exposures to BPA lay between the lowest and the highest estimates from the refined deterministic calculations. Since this should be the case, for a fully probabilistic compared with a deterministic approach, it is concluded that the FACET tool has been verified in this example. A recent EFSA draft opinion on exposure to BPA from different sources showed that canned foods were a major contributor and compared results from various models, including those from FACET. The results from FACET were overall conservative.


Assuntos
Compostos Benzidrílicos/análise , Contaminação de Alimentos/análise , Embalagem de Alimentos , Fenóis/análise , Compostos Benzidrílicos/toxicidade , Inquéritos sobre Dietas , Embalagem de Alimentos/estatística & dados numéricos , Alimentos em Conserva/análise , Alimentos em Conserva/toxicidade , Análise de Perigos e Pontos Críticos de Controle/métodos , Humanos , Metais Leves , Modelos Estatísticos , Nível de Efeito Adverso não Observado , Fenóis/toxicidade , Software , Reino Unido
19.
Food Chem Toxicol ; 59: 104-10, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23747712

RESUMO

Fluoride is considered important for health because of its beneficial effect on the prevention of dental caries and on bone development in the child population. However, excessive intake has negative effects. The main pathway for exposure is oral, through consumption of drinking water, and some food products. Therefore its bioaccessibility (quantity of the element solubilized during the digestive process) is a parameter to be considered when estimating the risk/benefit associated with this element. The aim of the present study was to evaluate the influence of the digestion phase, gastrointestinal digestion factors (pH, pepsin and bile salt concentrations) and the presence of cations on the bioaccessibility of fluoride from seafood products. The results show that the solubilization of fluoride takes place entirely during the gastric phase. Its bioaccessibility is strongly influenced by conditions that favor the formation of insoluble complexes of fluoride with other elements present in the matrix. The factors that are most influential in reducing its bioaccessibility are the increase in pH in the gastric phase, the presence of cations, especially in the intestinal phase, and a low concentration of bile salts.


Assuntos
Digestão , Fluoretos/metabolismo , Mucosa Gástrica/metabolismo , Mucosa Intestinal/metabolismo , Modelos Biológicos , Alimentos Marinhos/análise , Frutos do Mar/análise , Animais , Ácidos e Sais Biliares/metabolismo , Cálcio na Dieta/efeitos adversos , Cálcio na Dieta/metabolismo , Peixes , Fluoretos/análise , Fluoretos/química , Humanos , Concentração de Íons de Hidrogênio , Ferro na Dieta/efeitos adversos , Ferro na Dieta/metabolismo , Metais Leves/efeitos adversos , Metais Leves/metabolismo , Valor Nutritivo , Concentração Osmolar , Penaeidae/química , Pepsina A/metabolismo , Solubilidade
20.
Forensic Sci Int ; 223(1-3): 91-6, 2012 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-22995046

RESUMO

Scanning electron microscopy coupled with X-ray energy dispersive spectrometry (SEM-EDS) is extensively seen in the literature for the improvement of the macroscopic analysis of sharp lesions, but very few indications concerning its real potential in the forensic context, particularly in forensic anthropology, are at the moment available. This paper represents a pilot study for the analysis of the behaviour of metallic residues found on bone after sharp force injury. Fourteen lesions were made on human bone (radius), cleaned of all soft tissues, with seven different sharp tools (three metal instruments, three metal saws and a baked-clay knife). Tools and lesions underwent SEM-EDS. From 3 to 18 particles were detected on each lesion, whose diameter was included between 0.5 and 150 µm. In 58% of cases, particle composition was concordant with the instrument used. The results seem to suggest that sharp force injury frequently leaves relatively few residues on bone, particularly in the case of common types of metal. Saws showed slightly more contamination with other residues than knives, which may be explained by the capability of the saw's teeth to retain the residues of previously encountered material. In addition, metal residues related to the tool used to cut the bone were located on the edges/walls of lesions in the case of saw marks, whereas they were more frequently found on the kerf floor in the case of knives/scissors, with the exception of the baked clay knife which when it leaves residues at all, seemed to leave them equally divided between the floor, the edges and the surrounding bone.


Assuntos
Metais Pesados/análise , Metais Leves/análise , Rádio (Anatomia)/química , Silício/análise , Ferimentos Penetrantes/patologia , Patologia Legal , Humanos , Microscopia Eletrônica de Varredura , Rádio (Anatomia)/ultraestrutura , Espectrometria por Raios X
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