The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Donald E Canfield - One of the best experts on this subject based on the ideXlab platform.
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isotopic evidence for microbial Sulphate reduction in the early archaean era
Nature, 2001Co-Authors: Yanan Shen, Roger Buick, Donald E CanfieldAbstract:Sulphate-reducing microbes affect the modern sulphur cycle, and may be quite ancient1,2, though when they evolved is uncertain. These organisms produce sulphide while oxidizing organic matter or hydrogen with Sulphate3. At Sulphate concentrations greater than 1 mM, the sulphides are isotopically fractionated (depleted in 34S) by 10–40‰ compared to the Sulphate, with fractionations decreasing to near 0‰ at lower concentrations2,4,5,6. The isotope record of sedimentary sulphides shows large fractionations relative to seawater Sulphate by 2.7 Gyr ago, indicating microbial Sulphate reduction7. In older rocks, however, much smaller fractionations are of equivocal origin, possibly biogenic but also possibly volcanogenic2,8,9,10. Here we report microscopic sulphides in ∼3.47-Gyr-old barites from North Pole, Australia, with maximum fractionations of 21.1‰, about a mean of 11.6‰, clearly indicating microbial Sulphate reduction. Our results extend the geological record of microbial Sulphate reduction back more than 750 million years, and represent direct evidence of an early specific metabolic pathway—allowing time calibration of a deep node on the tree of life.
Ten Feizi - One of the best experts on this subject based on the ideXlab platform.
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high affinity binding of the leucocyte adhesion molecule l selectin to 3 Sulphated lea and lex oligosaccharides and the predominance of Sulphate in this interaction demonstrated by binding studies with a series of lipid linked oligosaccharides
Biochemical and Biophysical Research Communications, 1992Co-Authors: Paula J Green, Takuya Tamatani, Tomoyuki Watanabe, M Miyasaka, Akira Hasegawa, M Kiso, Chunting Yuen, M S Stoll, Ten FeiziAbstract:Abstract The binding of the leucocyte adhesion molecule L-selectin has been investigated toward several structurally defined lipid-linked oligosaccharides immobilized on silica gel chromatograms or plastic wells. In both assay systems the 3′-Sulphated Le a /Le x type tetrasaccharides were more strongly bound than 3′-sialyl analogues. A considerable binding was observed to the 3′-Sulphated oligosaccharide backbone in the absence of fucose but not to a 3′-sialyl analogue or fuco-oligosaccharide analogues lacking Sulphate or sialic acid. Affinity for other Sulphated saccharides: 3′-sulphoglucuronyl neolactotetraosyl ceramide and glycolipids with Sulphate 3′-linked to terminal or sub-terminal galactose or N-acetylgalactosamine was detected in the chromatogram assay only. These studies, together with earlier reports that L-selectin binding to endothelium is inhibited by sulphatide, highlight the relative importance of Sulphate in the adhesive specificity of this protein.
Nele De Belie - One of the best experts on this subject based on the ideXlab platform.
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resistance of concrete and mortar against combined attack of chloride and sodium Sulphate
Cement & Concrete Composites, 2014Co-Authors: Mathias Maes, Nele De BelieAbstract:Marine environments are typically aggressive to concrete structures, since sea water contains high concentrations of chlorides and Sulphates. To improve predictions of concrete durability within such environments, it is important to understand the attack mechanisms of these ions in combination. In this research, the reciprocal influence of Cl− and SO42− was investigated for four mixtures, namely with Ordinary Portland Cement, High Sulphate Resistant cement, and with Blast-Furnace Slag (50% and 70% cement replacement). Chloride penetration depths and diffusion coefficients were measured to investigate the influence of SO42− on Cl− attack. Besides, length and mass change measurements were performed to examine the influence of Cl− on SO42− attack. Since the formation of ettringite, gypsum and Friedel’s salt plays an important role, XRD-analyses were done additionally. It can be concluded that chloride penetration increases when the Sulphate content increases at short immersion periods, except for HSR concrete. Concerning the Sulphate attack, the presence of chlorides has a mitigating effect.
Ulf Lindahl - One of the best experts on this subject based on the ideXlab platform.
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pathophysiology of heparan Sulphate many diseases few drugs
Journal of Internal Medicine, 2013Co-Authors: Ulf Lindahl, Lena KjellenAbstract:Heparan Sulphate (HS) polysaccharides are covalently attached to the core proteins of various proteoglycans at cell surfaces and in the extracellular matrix. They are composed of alternating units of hexuronic acid and glucosamine, with Sulphate substituents in complex and variable yet cell-specific patterns. Whereas HS is produced by virtually all cells in the body, heparin, a highly Sulphated HS variant, is confined to connective-tissue-type mast cells. The polysaccharides interact with a multitude of proteins, mainly through ionic binding, and thereby control key processes in development and homoeostasis. Similar interactions also implicate HS in various pathophysiological settings, including cancer, amyloid diseases, infectious diseases, inflammatory conditions and some developmental disorders. Prospects for the development of HS-based drugs, which are still largely unrealized, are discussed.
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Low-Sulphated oligosaccharides derived from heparan Sulphate inhibit normal angiogenesis
Glycobiology, 1993Co-Authors: Rudolph Hahnenberger, Åke M. Jakobson, Akbar Ali Ansari, Carl Magnus Svahn, Thomas Wehler, Ulf LindahlAbstract:Abstract Heparin, with or without the addition of an adrenocorticosteroid, can inhibit normal angiogenesis in the chick embryo chorioallantoic membrane. Low- or non-Sulphated heparin fragments also have anti-angiogenic effect. Attempts to define a saccharide structure responsible for the anti-angiogenic effect implicated a -[GlcA beta 1,4-GlcNAc alpha 1,4]n-sequence. This structure represents the product of the initial polymerization reaction in heparin/heparan Sulphate biosynthesis. It persists in the non-Sulphated regions of heparan Sulphate and also occurs in the Escherichia coli K5 capsular polysaccharide. The K5 polysaccharide, fragments thereof down to octasaccharide size and analogous N-acetylated fragments of heparan Sulphate, all showed anti-angiogenic activity. Hyaluronan, however, with the isomeric -[GlcA beta 1,3-GlcNAc beta 1,4]n-structure was inactive. The anti-angiogenic activity of -[GlcA beta 1,4-GlcNAc alpha 1,4]n-containing saccharides was potentiated by the presence of L-iduronic acid and one or two O-Sulphate groups in the non-reducing-terminal disaccharide unit. The anti-angiogenic effect of these non- or low-Sulphated saccharides was unaffected by the addition of hydrocortisone. Endothelial cell surface-bound heparan Sulphate proteoglycans may represent a pool of precursors of anti-angiogenic oligosaccharides which may be of primary importance in the regulation of angiogenesis.
Stefan Demcak - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Reduction Of Barium Sulphate By Sulphate-Reducing Bacteria
Nova Biotechnologica et Chimica, 2015Co-Authors: Alena Luptakova, Ingrida Kotuličová, Magdalena Balintova, Stefan DemcakAbstract:Abstract Acid mine drainage (AMD) is a worldwide problem leading to contamination of water sources. AMD are characterized by low pH and high content of heavy metals and Sulphates. The barium salts application presents one of the methods for the Sulphates removing from AMD. Barium chloride, barium hydroxide and barium sulphide are used for the Sulphates precipitation in the form of barium Sulphate. Because of high investment costs of barium salts, barium sulphide is recycled from barium Sulphate precipitates. It can be recycled by thermic or bacterial reduction of barium Sulphate. The aim of our study was to verify experimentally the possibility of the bacterial transformation of BaSO4 to BaS by Sulphate-reducing bacteria. Applied BaSO4 came from experiments of Sulphates removal from Smolnik AMD using BaCl2.
