935 resultados para Mercury concentrations


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Adherence to aMediterranean diet (MD) is associated with a reduced risk of coronary heart disease. However, themolecular mechanisms involved are not fully understood. The aim of this studywas to compare the effects of 2MD with those of a lowfat- diet (LFD) on circulating inflammatory biomarkers related to atherogenesis. A total of 516 participants included in the PreventionwithMediterraneanDiet Studywere randomized into 3 intervention groups [MD supplementedwith virgin olive oil (MD-VOO); MD supplemented with mixed nuts (MD-Nuts); and LFD]. At baseline and after 1 y, participants completed FFQ and adherence to MD questionnaires, and plasma concentrations of inflammatory markers including intercellular adhesion molecule-1(ICAM-1), IL-6, and 2 TNF receptors (TNFR60 and TNFR80) were measured by ELISA. At 1 y, the MD groups had lower plasma concentrations of IL-6, TNFR60, and TNFR80 (P , 0.05), whereas ICAM-1, TNFR60, and TNFR80 concentrations increased in the LFD group (P , 0.002). Due to between-group differences, participants in the 2 MD groups had lower plasma concentrations of ICAM-1, IL-6, TNFR60, and TNFR80 compared to those in the LFD group (P # 0.028). When participants were categorized in tertiles of 1-y changes in the consumption of selected foods, those in the highest tertile of virgin olive oil (VOO) and vegetable consumption had a lower plasma TNFR60 concentration compared with those in tertile 1 (P,0.02).Moreover, the only changes in consumption thatwere associated with 1-y changes in the geometricmean TNFR60 concentrations were those of VOO and vegetables (P = 0.01). This study suggests that a MD reduces TNFR concentrations in patients at high cardiovascular risk.

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BACKGROUND AND OBJECTIVES: Hepcidin is the main hormone that regulates iron balance. Its lowering favours digestive iron absorption in cases of iron deficiency or enhanced erythropoiesis. The careful dosage of this small peptide promises new diagnostic and therapeutic strategies. Its measurement is progressively being validated and now its clinical value must be explored in different physiological situations. Here, we evaluate hepcidin levels among premenopausal female donors with iron deficiency without anaemia. MATERIALS AND METHODS: In a preceding study, a 4-week oral iron treatment (80 mg/day) was administered in a randomized controlled trial (n = 145), in cases of iron deficiency without anaemia after a blood donation. We subsequently measured hepcidin at baseline and after 4 weeks of treatment, using mass spectrometry. RESULTS: Iron supplementation had a significant effect on plasma hepcidin compared to the placebo arm at 4 weeks [+0·29 nm [95% CI: 0·18 to 0·40]). There was a significant correlation between hepcidin and ferritin at baseline (R(2) = 0·121, P < 0·001) and after treatment (R(2) = 0·436, P < 0·001). Hepcidin levels at baseline were not predictive of concentration changes for ferritin or haemoglobin. However, hepcidin levels at 4 weeks were significantly higher (0·79 nm [95% CI: 0·53 to 1·05]) among ferritin responders. CONCLUSIONS: This study shows that a 4-week oral treatment of iron increased hepcidin blood concentrations in female blood donors with an initial ferritin concentration of less than 30 ng/ml. Apparently, hepcidin cannot serve as a predictor of response to iron treatment but might serve as a marker of the iron repletion needed for erythropoiesis.

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A method to generate carbonylic compounds from alkynes under mild and neutral conditions, with excellent functional group compatibility and high yields, is described. Hydration takes place under catalytic conditions by using from 0.1 to 0.2 equivalents of the easily available and inexpensive mercury(II) p-toluensulfonamidate in a hydroalcoholic solution. After use the catalyst is iner tized and/or recycled ...

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Mercury kept in a garage of a residencial building in Rio de Janeiro was accidentally released and caused local (environmental and human) contamination. The concentration of mercury in indoor air of the most critical site reached 15.5 mg/m³. Outdoor air samples showed concentrations ranging from 0.37 to 6.6 mg/m³ . Seventy five per cent of the urine samples collected from 22 residents in the contaminated building showed levels of mercury higher than those observed in non exposed individuals (>6.9 mg/L); in 30% of these samples, the concentration was higher than 20 mg/L. These values show a high level of human contamination and the final consequences were not so serious owing to the quick action taken by one of the residents.

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We analysed concentrations of cadmium, lead, mercury and selenium in blood from males and females of the 2 sibling species of giant petrels, the northern Macronectes halli and the southern M. giganteus, breeding sympatrically at Bird Island (South Georgia, Antarctica). Blood samples were collected in 1998 during the incubation period, from 5 November to 10 December. Between species, cadmium and lead concentrations were significantly higher for northern than for southern giant petrels, which probably resulted from northern giant petrels wintering in more polluted areas (mainly on the Patagonian Shelf and Falkland Islands) compared to southern giant petrels (wintering mainly around South Georgia and the South Sandwich Islands). Between sexes, cadmium concentrations were significantly higher for females than for males in both species, corresponding to the more pelagic habits of females compared to the more scavenging habits of males. Lead and cadmium concentrations in circulating blood decreased significantly over the incubation period, suggesting that when breeding at Bird Island, exposure to the source of pollution had ended, and these metals had been cleared from the blood and excreted, or rapidly transferred to other tissues. Association of lead and cadmium with a common source of pollution was further corroborated by a significant positive correlation between the levels of the 2 elements found. Mercury levels were similar between the species, but showed an opposite trend between sexes, with males showing higher levels than females in northern giant petrels, and the opposite was true in southern giant petrels, with no changes throughout incubation. Selenium levels were similar between sexes, but significantly greater for northern than for southern giant petrels. Moreover, there was a significant increase in the selenium levels over the incubation period in northern giant petrels. Age of adult birds did not affect metal concentrations. Coefficients of variation of metal levels were consistently lower for northern than for southern giant petrels, particularly for mercury, suggesting that the former species is more dietary specialised than the latter. Contaminant analyses, when combined with accurate information on seabird movements, obtained through geolocation or satellite tracking, help us to understand geographic variation of pollution in the marine environment.

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The concentrations of mercury in surface sediments (<63mum fraction) from Santos-Cubatão Estuary, located in State of São Paulo, southeast Brazil, were determined to obtain the level of contamination in this highly polluted area. Fifteen stations distributed though seven rivers were sampled (156 samples collected) from September 1997 to August 1998 (12 stations sampled monthly) and during March, June, September and December 1998 (three stations sampled quarterly). The levels of mercury varied from 0.10 to 6.77 ppm, with the index of geoaccumulation of the rivers varying between grades 1 and 3 (annual average). The Cubatão is the most polluted river and the main agent of Hg dispersion in the study area. Geochemical data revealed that Hg levels in surface from Santos-Cubatão Estuary at present are as elevated as in past (for instance, by comparison 1980's), when Cubatão city was known as one of the most polluted cities in the world.

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The interaction of mercury(II) with sulfathiazole has been analyzed. IR and NMR spectral studies suggest a coordination of Hg(II) with the Nthiazolic atom, unlike related Hg-sulfadrugs compounds. The complex was screened for its activity against Escherichia coli, showing an appreciable antimicrobial activity compared with the ligand.

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The Río Negro Formation (late Miocene-early Pliocene) mainly consists of continental deposits, but it contains a middle member of marine origin. It represents a transgressive-regressive sequence that can be seen at several outcrops along the N Patagonian coast. The taphonomical approach to the El Espigón marine deposits permits the identification of four main layers containing different kinds of skeletal accumulation, which mainly consist of oyster shells [Crassostrea patagonica (D'Orbigny, 1842)]. These concentrations display three different morphologies (pouches, pavements and bouquets) with a different taphonomic signature. These deposits were formed in shallow marine environments influenced by wave activity that produced valve concentrations of different entities. They contain several shell beds that represent event, composite, hiatal to lag skeletal concentrations. Traces of bioturbation in the sediment (Thalassinoides, Teichichnus) and bioerosion on the shells (Entobia, Gastrochaeonolites, Caulostrepsis), and encrusters (cirripeds, bryozoans), are also abundant in the outcrop and consititue common components of these Miocene materials. Layers 1 and 2 of the sequence were deposited in shoreface/foreshore environments at the beginning of a highstand systems tract, while layers 3 and 4 were deposited at the end, or at the beginning of a forced regression, in foreshore environments. A final erosional episode cut the top of the layer 4, which truncated the abundant bioturbaation developed there.

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Total sediment and water organic carbon and nutrient (nitrogen and phosphorus) concentrations of different environment types of a Mediterranean coastal wetland (temporary and brackish, temporary and freshwater, semi-permanent and brackish, and permanent and brackish basins) were analysed during two hydroperiods. A nitrogen limitation was found for both sediment and water. The total organic carbon concentration of the water was significantly related to the water level, which varies throughout the hydroperiods. In contrast, the total organic carbon concentration of the sediment was not related to water level. However, significant differences in total organic carbon of the sediment were found between hydroperiods. On the other hand, total organic carbon of the sediment varied spatially, being higher in temporary brackish basins with lower sand content, and lower in permanent and semi-permanent brackish basins with higher sand content

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Soils play an important role in the biogeochemical cycle of mercury as a sink for and source of this metallic species to atmospheric and hydrological compartments. In the study reported here, various types of soil were evaluated to ascertain the influence of parameters such as pH, organic matter content, Fe, Al, sand, silt, clay, C/H, C/N, C/O atomic ratios, and cation exchange capacity on the distribution of Hg in Amazonia's mid-Negro River basin. The data obtained were interpreted by multivariate exploratory analyses (hierarchical cluster analysis and principal component analysis), which indicated that organic matter plays an important role in mercury uptake in the various soils studied. The soils in floodable areas were found to contain 1.5 to 2.8-fold higher Hg concentrations than those in non-floodable areas. Since these soils are flooded almost year-round, they are less available to participate in redox processes at the soil/atmosphere interface. Hence, floodable areas, which comprise humic-rich soils, accumulate more mercury than non-floodable soils, thus playing an important role in the biogeochemical cycle of Hg in Amazonia's mid-Negro River basin.

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Increasing natural gas use in Brazil triggered a discussion of its role as a Hg source. We show that Hg emissions to the atmosphere from fossil fuel combustion for power generation in Brazil contribute with 6.2% (4.2 t yr-1) to the total anthropogenic Hg atmospheric emissions, with coal combustion and biomass burning as major sources. Natural gas contributes with 0.04 t yr-1, mostly from electricity generation (88%) and industrial uses (7.6%). Preliminary results on Hg concentrations in natural gas suggest that a large fraction of it is trapped during refining and transport, which may create Hg point sources between extraction and consumption.

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In this work carrier-facilitated transport of mercury(II) against its concentration gradient from aqueous 0.04 M hydrochloric acid solution across a liquid membrane containing isopropyl 2-[(isopropoxycarbothiolyl)disulfanyl]ethane thioate (IIDE) as the mobile carrier in chloroform has been investigated. Sodium thiocyanate solution (1.6 M) was the most efficient receiving phase agent among several aqueous reagents tested. Various parameters such as investigated. Under optimum conditions the transport of Hg(II) across the liquid membrane is more than 97% after 2.5 h. The carrier, IIDE, selectively and efficiently could able to transport Hg (II) ions in the presence of other associated metal ions in binary systems.

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Mercury distribution and geochemical support on the Continental Margin was evaluated at the Campos Basin, Rio de Janeiro state, Brazil. The average concentrations for all analyzed elements were, respectively, 20 ± 5 ng g-1 (Hg); 30 ± 14 mg g-1 (Al); 16 ± 6 mg g-1 (Fe), and 254 ± 83 µg g-1 (Mn). Silt and clay content, total carbonate and Hg, and organic carbon increased with depth. Finally, the relationship between Hg and silt clay showed significant positive correlation. Total Hg concentrations are the background level described primarily (~40 ng g-1).

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Behavior of mercury in soil profiles with archaeological black earth (ABE) and surroundings area (SA) from Sítio Ilha de Terra, Caxiuanã, can provide information on anthropogenic activity of the Amazonian habitat. The samples of ABE and SA soil profiles were submitted to mineralogical chemical (total and sequential) analysis. The data show that the Hg occurs mainly in goethite and kaolinite in the two soil profiles. The highest concentrations of Hg and Fe are observed in the SA profile. These results indicate that the prehistoric human occupation contributed to the decrease of the concentration of Hg in soil ABE from Caxiuanã.