919 resultados para low-molecular-weight and high-sulfate-content


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Objective: To examine the possibility that low birth weight is a feature of the inherited predisposition to high blood pressure.

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Modern carbonate sedimentation takes place on the northern Mauritanian shelf (20°N), where typical tropical components (e.g. hermatypic reefs, calcareous green algae) are absent. Such deposits are reminiscent of extratropical sediment in the geological record. The tropical open shelf of Mauritania is influenced by large siliciclastic dust input and upwelling, highly fertilizing the ocean, as well as strongly limiting the light penetration. In this context, temperature does not appear to be the steering factor of carbonate production. This thesis describes the depositional system of the Golfe d'Arguin off Mauritania and focuses on environmental conditions that control the depositional pattern, in particular carbonate production. The description of this modern analogue provides a tool for paleoenvironmental interpretation of ancient counterparts. The Golfe d'Arguin is a broad shallow shelf comprising extensive shoals (<10 m water depth; i.e. the Banc d'Arguin) on the inner shelf where waters warm up. The sediments collected in water depths between 4 and 600 m are characterized by mixed carbonate and siliciclastic (dust) deposits. They vary from clean coarse-grained, almost pure carbonate loose sediments to siliciclastic-dominated fine-grained sediments. The carbonate content and sediment grain size show a north-south decreasing pattern through the Golfe d'Arguin and are controlled by the hydraulic regime influenced by wind-driven surface currents, swell, and tidal currents. The carbonate grain association is heterozoan. Components include abundant molluscs, foraminifers, and worm tubes, as well as barnacles and echinoderms, elements that are also abundant in extratropical sediments. The spatial distribution of the sedimentary facies of the Golfe d'Arguin does not display a depth zonation but rather a mosaic (i.e. patchy distribution). The depth and climatic signatures of the different sedimentary facies are determined by taxonomic and ecological investigations of the carbonate-secreting biota (molluscs and foraminifers). While certain planktonic foraminifers and molluscs represent upwelling elements, other components (e.g. mollusc and benthic foraminifer taxa) demonstrate the tropical origin of the sediment. The nutrient-rich (and thus also low light-penetration) conditions are reflected in the fact that symbiotic and photosynthetic carbonate-producing organisms (e.g. hermatypic corals) are absent. The Mauritanian deposits represent an environment that is rare in the modern world but might have been more common in the geological past when global temperatures were higher. Taxonomic and ecological studies allow for distinguishing carbonate sediments formed under either tropical high-nutrient or extratropical conditions, thus improving paleoclimate reconstruction.

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A series of core samples taken during Cruise 79 of Glomar Challenger, drilling offshore Morocco (Mazagan Plateau), is analyzed for their low-molecular-weight hydrocarbon contents. Fifty-four samples from DSDP Holes 544A, 545, 547A, and 547B, deep frozen on board immediately after recovery, are studied by a hydrogen-stripping/thermovaporization technique combined with capillary gas chromatography. Thirty-eight compounds in the C2-C8 molecular range, including saturated, olefinic, and aromatic hydrocarbons, are identified. Because of large differences in organic carbon contents, the total C2-C8 hydrocarbon concentrations vary from about 20 to 1500 ng/g dry sediment weight in the whole sample series. Organic-carbon normalized values are about 3.2 x 10**4 ng/g Corg for Lithologic Subunits IIIA and IIIB at Site 545 (Cenomanian to Aptian) and 1.0 x 10**5 ng/g Corg for Unit V at Site 547 (Cenomanian to Albian) reflecting the slightly more advanced maturity stage at the latter site. Values exceeding 10**5 ng/g Corg (Site 545) and 2 x 10**5 ng/g Corg (Site 547) are associated with samples that are very lean in organic carbon and are generally rich in carbonate. These samples are enriched by small amounts of gaseous hydrocarbons. A detailed study of individual hydrocarbon concentrations, plotted against depth, reveal additional indications for migration phenomena. At Site 547, for instance, the most mobile hydrocarbons studied (e.g., ethane) appear to migrate by diffusion or a related process from more than 700 m depth toward the surface.

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C2-C8 hydrocarbons (36 compounds identified) from 56 shipboard sealed, deep-frozen core samples of DSDP Leg 71, Site 511, Falkland Plateau, South Atlantic, were analyzed by a combined hydrogen stripping-thermovaporization method. Concentrations, which represent hydrocarbons dissolved in the pore water and adsorbed to the mineral surfaces of the sediment, vary from 24 ng/g of dry weight sediment in Lithologic Unit 4 to 17,400 ng/g in Lithologic Unit 6 ("black shale" unit). Likewise, the organic carbon normalized C2-C8 hydrocarbon concentrations range from 104 to 3.5 x 105 ng/g Corg. The latter value is more than one order of magnitude lower than expected for petroleum source beds in the main phase of oil generation. The low maturity at 600 meters depth is further supported by light hydrocarbon concentration ratios. The change of the kerogen type from Lithologic Unit 5 (Type III) to 6 (Type II) is evidenced by changes in the C6 and C7 hydrocarbon composition. Redistribution phenomena are observed close to the Tertiary-Cretaceous unconformity and at the contact between the "black shale" unit and the overlying Cretaceous chalks and claystones. Otherwise, the low molecular weight hydrocarbons in Hole 511 are formed in situ and remain at their place of formation. The core samples turned out to be contaminated by large quantities of acetone, which is routinely used as a solvent during sampling procedures onboard Glomar Challenger.

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Low-molecular-weight fucoidan (LMWF) is a sulfated polysaccharide extracted from brown seaweed that presents antithrombotic and pro-angiogenic properties. However, its mechanism of action is not well-characterized. Here, we studied the effects of LMWF on cell signaling and whole genome expression in human umbilical vein endothelial cells and endothelial colony forming cells. We observed that LMWF and vascular endothelial growth factor had synergistic effects on cell signaling, and more interestingly that LMWF by itself, in the absence of other growth factors, was able to trigger the activation of the PI3K/AKT pathway, which plays a crucial role in angiogenesis and vasculogenesis. We also observed that the effects of LMWF on cell migration were PI3K/AKT-dependent and that LMWF modulated the expression of genes involved at different levels of the neovessel formation process, such as cell migration and cytoskeleton organization, cell mobilization and homing. This provides a better understanding of LMWF's mechanism of action and confirms that it could be an interesting therapeutic approach for vascular repair.

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Mushrooms have the ability to promote apoptosis in tumor cell lines, but the mechanism of action is not quite well understood. Inhibition of the interaction between Bcl-2 and pro-apoptotic proteins could be an important step that leads to apoptosis. Therefore, the discovery of compounds with the ability to inhibit Bcl-2 is an ongoing research topic in drug discovery. In this study, we started by analyzing Bcl-2 experimental structures that are currently available in Protein Data Bank database. After analysis of the more relevant Bcl-2 structures, 4 were finally selected. An analysis of the best docking methodology was then performed using a cross-docking and re-docking approach while testing 2 docking softwares: AutoDock 4 and AutoDock Vina. Autodock4 provided the best docking results and was selected to perform a virtual screening study applied to a dataset of 40 Low Molecular Weight (LMW) compounds present in mushrooms, using the selected Bcl-2 structures as target. Results suggest that steroid are the more promising family, among the analyzed compounds, and may have the ability to interact with Bcl-2 and this way promoting tumor apoptosis. The steroids that presented lowest estimated binding energy (ΔG) were: Ganodermanondiol, Cerevisterol, Ganoderic Acid X and Lucidenic Lactone; with estimated ΔG values between -8,45 and -8,23 Kcal/mol. A detailed analysis of the docked conformation of these 4 top ranked LMW compounds was also performed and illustrates a plausible interaction between the 4 top raked steroids and Bcl-2, thus substantiating the accuracy of the predicted docked poses. Therefore, tumoral apoptosis promoted by mushroom might be related to Bcl-2 inhibition mediated by steroid family of compounds.

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Objective: Cost-effectiveness analysis of a 6-month treatment of apixaban (10 mg/12h, first 7 days; 5 mg/12h afterwards) for the treatment of the first event of venous thromboembolism (VTE) and prevention of recurrences, versus low-molecular-weight heparins/vitamin K antagonists treatment (LMWH/VKA). Material and methods: A lifetime Markov model with 13 health states was used for describing the course of the disease. Efficacy and safety data were obtained from AMPLIFY and AMPLIFY-EXT clinical trials; health outcomes were measured as life years gained (LYG) and quality-adjusted life years (QALY). The chosen perspective of this analysis has been the Spanish National Health System (NHS). Drugs, management of VTE and complications costs were obtained from several Spanish data sources (€, 2014). A 3% discount rate was applied to health outcomes and costs. Univariate and probabilistic sensitivity analyses (SA) were performed in order to assess the robustness of the results. Results: Apixaban was the most effective therapy with 7.182 LYG and 5.865 QALY, versus 7.160 LYG and 5.838 QALYs with LMWH/VKA. Furthermore, apixaban had a lower total cost (€13,374.70 vs €13,738.30). Probabilistic SA confirmed dominance of apixaban (led to better health outcomes with less associated costs) in 89% of the simulations. Conclusions: Apixaban 5 mg/12h versus LMWH/VKA was an efficient therapeutic strategy for the treatment and prevention of recurrences of VTE from the NHS perspective.