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Journal articles on the topic "Sulfated"
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Vicente, C. P., P. Zancan, L. L. Peixoto, R. Alves-Sá, F. S. Araújo, P. A. S. Mourão, and M. S. G. Pavão. "Unbalanced Effects of Dermatan Sulfates with Different Sulfation Patterns on Coagulation, Thrombosis and Bleeding." Thrombosis and Haemostasis 86, no. 11 (2001): 1215–20. http://dx.doi.org/10.1055/s-0037-1616054.
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SummaryWe compared the anticoagulant, antithrombotic and bleeding effects of highly sulfated dermatan sulfates from invertebrates and their mammalian counterpart. An invertebrate dermatan sulfate containing 2-O-sulfated α-L-iduronic acid and 4-O-sulfated N-acetyl-β-D-galactosamine residues is a potent anticoagulant due to a high heparin cofactor II activity. It inhibits thrombin due to the formation of a covalent complex with heparin cofactor II, as in the case of mammalian dermatan sulfate, but the effect occurs at lower concentrations for the invertebrate polysaccharide. Surprisingly, the invertebrate dermatan sulfate has a lower potency to prevent thrombus formation on an experimental model and a lower bleeding effect in rats than the mammalian dermatan sulfate. In contrast, another invertebrate dermatan sulfate, also enriched in 2-O-sulfated α-L-iduronic acid, but in this case sulfated at O-6 position of the N-acetyl-β-D-galactosamine units, has no in vitro or in vivo anticoagulant activity, does not prevent thrombus formation but shows a bleeding effect similar to the mammalian glycosaminoglycan. Overall, these results demonstrate unbalanced effects of dermatan sulfates with different sulfation patterns on coagulation, thrombosis and bleeding, and raise interesting questions concerning the relationship among these three biological actions of sulfated polysaccharides.
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PAVÃO, MAURO S. G. "Structure and anticoagulant properties of sulfated glycosaminoglycans from primitive Chordates." Anais da Academia Brasileira de Ciências 74, no. 1 (March 2002): 105–12. http://dx.doi.org/10.1590/s0001-37652002000100007.
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Dermatan sulfates and heparin, similar to the mammalian glycosaminoglycans, but with differences in the degree and position of sulfation were previously isolated from the body of the ascidian Styela plicata and Ascidia nigra. These differences produce profound effects on their anticoagulant properties. S. plicata dermatan sulfate composed by 2-O-sulfatedalpha-L-iduronic acid and 4-O-sulfated N-acetyl-beta-D-galactosamine residues is a potent anticoagulant due to a high heparin cofactor II activity. Surprisingly, it has a lower potency to prevent thrombus formation on an experimental model and a lower bleeding effect in rats than the mammalian dermatan sulfate. In contrast, A. nigra dermatan sulfate, also enriched in 2-O-sulfated alpha-L-iduronic acid, but in this case sulfated at O-6 of the N-acetyl-beta-D-galactosamine units, has no in vitro or in vivo anticoagulant activity, does not prevent thrombus formation but shows a bleeding effect similar to the mammalian glycosaminoglycan. Ascidian heparin, composed by 2-O-sulfated alpha-L-iduronic acid, N- and 6-O-sulfated glucosamine (75%) and alpha-L-iduronic acid, N- and 6-O-sulfated glucosamine (25%) disaccharide units has an anticoagulant activity 10 times lower than the mammalian heparin, is about 20 times less potent in the inhibition of thrombin by antithrombin, but has the same heparin cofactor II activity as mammalian heparin.
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Valentová, Kateřina, Kateřina Purchartová, Lenka Rydlová, Lenka Roubalová, David Biedermann, Lucie Petrásková, Alena Křenková, et al. "Sulfated Metabolites of Flavonolignans and 2,3-Dehydroflavonolignans: Preparation and Properties." International Journal of Molecular Sciences 19, no. 8 (August 9, 2018): 2349. http://dx.doi.org/10.3390/ijms19082349.
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Silymarin, an extract from milk thistle (Silybum marianum) fruits, is consumed in various food supplements. The metabolism of silymarin flavonolignans in mammals is complex, the exact structure of their metabolites still remains partly unclear and standards are not commercially available. This work is focused on the preparation of sulfated metabolites of silymarin flavonolignans. Sulfated flavonolignans were prepared using aryl sulfotransferase from Desulfitobacterium hafniense and p-nitrophenyl sulfate as a sulfate donor and characterized by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR). Their 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and N,N-dimethyl-p-phenylenediamine (DMPD) radical scavenging; ferric (FRAP) and Folin–Ciocalteu reagent (FCR) reducing activity; anti-lipoperoxidant potential; and effect on the nuclear erythroid 2-related factor 2 (Nrf2) signaling pathway were examined. Pure silybin A 20-O-sulfate, silybin B 20-O-sulfate, 2,3-dehydrosilybin-20-O-sulfate, 2,3-dehydrosilybin-7,20-di-O-sulfate, silychristin-19-O-sulfate, 2,3-dehydrosilychristin-19-O-sulfate, and silydianin-19-O-sulfate were prepared and fully characterized. Sulfated 2,3-dehydroderivatives were more active in FCR and FRAP assays than the parent compounds, and remaining sulfates were less active chemoprotectants. The sulfated flavonolignans obtained can be now used as authentic standards for in vivo metabolic experiments and for further research on their biological activity.
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Pancake, SJ, GD Holt, S. Mellouk, and SL Hoffman. "Malaria sporozoites and circumsporozoite proteins bind specifically to sulfated glycoconjugates." Journal of Cell Biology 117, no. 6 (June 15, 1992): 1351–57. http://dx.doi.org/10.1083/jcb.117.6.1351.
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Circumsporozoite (CS) proteins, which densely coat malaria (Plasmodia) sporozoites, contain an amino acid sequence that is homologous to segments in other proteins which bind specifically to sulfated glycoconjugates. The presence of this homology suggests that sporozoites and CS proteins may also bind sulfated glycoconjugates. To test this hypothesis, recombinant P. yoelii CS protein was examined for binding to sulfated glycoconjugate-Sepharoses. CS protein bound avidly to heparin-, fucoidan-, and dextran sulfate-Sepharose, but bound comparatively poorly to chondroitin sulfate A- or C-Sepharose. CS protein also bound with significantly lower affinity to a heparan sulfate biosynthesis-deficient mutant cell line compared with the wild-type line, consistent with the possibility that the protein also binds to sulfated glycoconjugates on the surfaces of cells. This possibility is consistent with the observation that CS protein binding to hepatocytes, cells invaded by sporozoites during the primary stage of malaria infection, was inhibited by fucoidan, pentosan polysulfate, and heparin. The effects of sulfated glycoconjugates on sporozoite infectivity were also determined. P. berghei sporozoites bound specifically to sulfatide (galactosyl[3-sulfate]beta 1-1ceramide), but not to comparable levels of cholesterol-3-sulfate, or several examples of neutral glycosphingolipids, gangliosides, or phospholipids. Sporozoite invasion into hepatocytes was inhibited by fucoidan, heparin, and dextran sulfate, paralleling the observed binding of CS protein to the corresponding Sepharose derivatives. These sulfated glycoconjugates blocked invasion by inhibiting an event occurring within 3 h of combining sporozoites and hepatocytes. Sporozoite infectivity in mice was significantly inhibited by dextran sulfate 500,000 and fucoidan. Taken together, these data indicate that CS proteins bind selectively to certain sulfated glycoconjugates, that sporozoite infectivity can be inhibited by such compounds, and that invasion of host hepatocytes by sporozoites may involve interactions with these types of compounds.
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Barron, Denis, and Ragai K. Ibrahim. "Synthesis of Flavonoid Sulfates. II. The Use of Aryl Sulfatase in the Synthesis of Flavonol-3-sulfates." Zeitschrift für Naturforschung C 43, no. 9-10 (October 1, 1988): 625–30. http://dx.doi.org/10.1515/znc-1988-9-1001.
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Abstract The rates of aryl sulfatase hydrolysis of several 7-, 4′- and 3-sulfated flavonoids were compared and found to follow the order 7 or 4′ >>> 3. The complete resistance of the 3-sulfate ester to enzyme hydrolysis provided a unique and convenient method for the synthesis of a number of naturally occurring flavonol-3-sulfates from the corresponding higher sulfated analogs in quantitative yield.
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Løvtrup-Rein, Huguette. "Biosynthesis of sulfated proteoglycans in amphibian embryonal cells." Bioscience Reports 9, no. 2 (April 1, 1989): 213–22. http://dx.doi.org/10.1007/bf01115998.
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The synthesis of sulfated proteoglycans in small explants from various parts of late blastulae from Ambystoma mexicanum or Xenopus laevis was investigated by incorporation of radioactive sulfate or glucosamine and galactosamine in media of low, normal or high tonicity. The explants differentiated into ciliated aggregates or fibroblast-like cells, or remained undifferentiated depending upon their origin in the embryo. High tonicity induces the explants to dissociated and prevents morphological differentiation, while low tonicity hardly affects this process. Yet, both types of media decrease the incorporation into glycosaminoglycans to various degrees, ranging from 40 to 80%, depending upon the species. In Xenopus, the uptake of sulfate is inhibited by as much as 90% in high tonicity media. The rate of incorporation of label is approximately twice as much in mesodermal as in animal or vegetal aggregates, which do not differ significantly. Animal aggregates from Ambystoma, however, revealed an exceptionally high uptake of sulfate. The relative distribution of chondroitin sulfates and heparan sulfates is not affected by changes in tonicity, except in Xenopus where high tonicity severely suppresses the synthesis of heparan sulfates, and is independent of the type of aggregate. The relationship between the synthesis of sulfated proteoglycans and processes involved in cell differentiation, especially cell adhesion, is discussed.
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Peres-Sampaio, Carlos Eduardo, Simone Thorp Palumbo, and José Roberto Meyer-Fernandes. "An Ecto-ATPase Activity Present in Leishmania tropica Stimulated by Dextran Sulfate." Zeitschrift für Naturforschung C 56, no. 9-10 (October 1, 2001): 820–25. http://dx.doi.org/10.1515/znc-2001-9-1023.
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AbstractIn this study we report the effects of sulfated polysaccharides on the ecto-ATPase activity of intact cells of Leishmania tropica. Increasing concentrations of dextran sulfate stimulated progressively the ecto-ATPase activity, but did not modify other ecto-enzymes present on the surface of this parasite, such as 5′ nucleotidase, 3′nucleotidase and a membrane-bound acid phosphatase activity. This stimulation was not observed when other sulfated polysaccharides such as chondroitin sulfates and heparin were tested. It depends on size and charge of the dextran sulfated molecule. When the cells were incubated in the presence of dextran sulfate Mr 8,000; 40,000 and 500,000 the stimulation of the ecto-ATPase activity was 11%; 23%; and 63%, respectively, and the stimulation was not observed when desulfated dextran (Mr 40,000) was used. The effects of dextran sulfate also depend on pH of the medium. At pH 7.5, the stimulation was over 60%, whereas at pH 8.5 only 25%. The effects of dextran sulfate 500,000 on the ecto-ATPase activity was totally abolished by spermidine and partially by putrescine, two polyamines synthesized and released by Leishmania.
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Reinehr, Thomas, Alberto Sánchez-Guijo, Nina Lass, and Stefan A. Wudy. "Higher steroid sulfation is linked to successful weight loss in obese children." Endocrine Connections 7, no. 10 (October 2018): 1020–30. http://dx.doi.org/10.1530/ec-18-0233.
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Objective Little information is available on the steroid sulfates profile in obese children. Therefore, we examined whether sulfated steroids are linked with weight status and associated comorbidities in obese children. Methods We analyzed 66 obese children (mean age 10.5 ± 2.5 years, 57.6% female, 53.9% prepubertal, mean BMI 27.0 ± 4.6 kg/m2, 50% with BMI-SDS reduction >0.5, 50% without BMI-SDS reduction) who participated in an outpatient 1-year intervention program based on exercise, behavior and nutrition therapy. We measured intact sulfated steroids (cholesterol sulfate (CS), pregnenolone sulfate (PregS), 17αOH pregnenolone sulfate (17OH-PregS), 16αOH dehydroepiandrosterone sulfate (16OH-DHEAS), DHEAS, androstenediol-3-sulfate, androsterone sulfate and epiandrosterone sulfate) by LC–MS/MS, and insulin resistance index HOMA, lipids, blood pressure at baseline and 1 year later. Results All sulfated steroids except 17OH-PregS, 16OH-DHEAS, androsterone sulfate and epiandrosterone sulfate were higher in boys compared to girls. Concentrations of CS before intervention were higher in children who lost weight. After 1 year of treatment, both groups showed increased levels of DHEAS, 16OH-DHEAS and androstenediol-3-sulfate, but PregS was only increased in children with weight loss. None of the steroid sulfates was significantly related to cardiovascular risk factors or HOMA except 17OH-PregS, which was associated with systolic blood pressure both in cross-sectional (β-coefficient: 0.09 ± 0.07, P = 0.020) and longitudinal analyses (β-coefficient: 0.06 ± 0.04, P = 0.013) in multiple linear regression analyses. Conclusions Since higher steroid sulfation capacity was associated with successful weight intervention in children disruption of sulfation may be associated with difficulties to lose weight. Future studies are necessary to prove this hypothesis.
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Kazachenko, Aleksandr Sergeyevich, Vladimir Aleksandrovich Levdansky, Aleksandr Vladimirovich Levdansky, and Boris Nikolayevich Kuznetsov. "MATHEMATICAL OPTIMIZATION OF THE PROCESS OF BIRCH WOOD XYLAN SULFATION BY SULFAMIC ACID IN N, N-DIMETHYLFORMAMIDE MEDIUM." chemistry of plant raw material, no. 2 (June 10, 2021): 87–94. http://dx.doi.org/10.14258/jcprm.2021027558.
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The effect of temperature and duration of sulfation of birch wood xylan by sulfamic acid in N, N-dimethylformamide (DMF) medium in the presence of urea on the yield of sulfated xylan and on the sulphur content was studied. By mathematical optimization, the sulfation conditions have been established allowing to achieve a high yield of the obtained xylan sulfates with a high sulphur content. Under optimal sulfation conditions: temperature 100±3 °C, duration 1.5 hours, the yield of sulfated xylan reaches to 63% mas. and the content of sulfur – 17.6% mas. The presence of sulfate groups in sulfated xylan samples obtained under optimal conditions was confirmed by elemental analysis and FTIR and 13C NMR spectroscopy.
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Chambers, W. H., and T. N. Oeltmann. "The effects of hexose 6-O-sulfate esters on human natural killer cell lytic function." Journal of Immunology 137, no. 5 (September 1, 1986): 1469–74. http://dx.doi.org/10.4049/jimmunol.137.5.1469.
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Abstract Natural cell-mediated cytotoxicity (NCMC) is inhibited by some neutral hexoses and hexose phosphates at 25 to 100 mM concentrations. In this study we describe the effects of hexose 6-O-sulfate esters on NCMC against K-562 target cells. Mannose 6-sulfate, galactose 6-sulfate, N-acetylglucosamine 6-sulfate, and N-acetylgalactosamine 6-sulfate inhibit NCMC in a dose-dependent manner at concentrations of 10 mM and below. Inhibitory effects of mannose 6-sulfate and galactose 6-sulfate were evident at concentrations as low as 1.25 mM. The neutral forms of these sugars, glucose and glucose 6-sulfate, did not inhibit NCMC over this range of concentrations. Comparison of the inhibitory effects of sulfated and phosphorylated forms of mannose and galactose indicated that the sulfated forms are much more potent inhibitors. Formation of effector cell:target cell conjugates was unaffected by the presence of sugar sulfates. Calcium pulse experiments demonstrated that inhibitory effects of sugar sulfates were exerted after the Ca++-dependent triggering step in the NK lytic process. Kinetic studies showed that addition of sugars as long as 60 min after initiation of cultures yielded potent inhibitory effects. Sugar sulfates were not toxic for effector cell populations and effectors were not refractory for lytic function after removal of sugars. Sugar sulfates were inhibitory against multiple tumor types in both human and murine NK lytic assays. These results suggest that the sugar sulfates inhibit NK cells at a postconjugation, posttriggering step involving lectin-like receptors or lectin-like molecules.
Dissertations / Theses on the topic "Sulfated"
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Mehta, Akul. "Synthetic, Sulfated, Lignin-Based Anticoagulants." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/598.
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Chemoenzymatically synthesized low molecular weight lignin polymers have been previously found to be potent inhibitors of a number of serine proteases via allosteric mechanisms targeting heparin binding sites. Herein, we describe the creation of synthetic sulfated β-O4 lignin (SbO4L) polymer, which is more homogenous compared to previous lignins with respect to its inter-monomeric linkage. SbO4L is a selective inhibitor of thrombin and plasmin. SbO4L was found to act via a unique mechanism targeting thrombin exosite 2 in a manner similar to platelet glycoprotein Ibα (GPIbα). Advanced hemostasis and thrombosis assays demonstrated that SbO4L acts via a dual mechanism: as an anticoagulant, by allosteric inhibition of thrombin catalysis; and as an antiplatelet agent, by competing with platelet GPIbα. These mechanisms are comparable in potency to low molecular weight heparins currently used in the market, indicating that targeting exosite 2 may yield clinically useful drugs in the future. Since the β-O4 type lignin was found to be selective for thrombin and plasmin, we hypothesized that other scaffolds from lignins could be potent inhibitors of other serine proteases. In particular, we screened a library of synthetic sulfated small molecules against factor XIa – an emerging target for prophylactic anticoagulation. Our search identified a sulfated benzofuran trimer (a mimic of β-5 type linkage found in lignins) as a potent inhibitor of factor XIa. Surprisingly, this inhibitor did not compete with heparin. A plausible binding site in the A3 domain of factor XIa was proposed by using molecular modeling techniques. The binding pose demonstrated good correlation with the structure activity data from in vitro studies. Further confirmation that the apple domains were required was proved by testing the trimer against recombinant catalytic domain. A 40-fold decrease in activity was observed. A temperature-dependant perrin plot demonstrated that factor XIa undergoes a large conformational change in the presence of the trimer, which is possibly converting the enzyme back into the zymogen-like shape. In general, the synthetic sulfated lignins can act as a useful foundation to develop anticoagulant, antiplatelet, and anti-inflammatory molecules in the future.
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Pereira, Amália Luz Costa. "Efeito das condições de preparação sobre as propriedades do óxido de zircônio sulfatado contendo ferro." Programa de Pós-Graduação em Química da UFBA, 2004. http://www.repositorio.ufba.br/ri/handle/ri/9949.
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Catalisadores baseados em óxidos sulfatados possuem diversas aplicações industriais, principalmente em reações que demandam sítios ácidos fortes. Visando a desenvolver métodos para obter óxidos ácidos, neste trabalho se estudou o efeito dos métodos de preparação nas propriedades dos óxidos de zircônio dopado com ferro.Os precursores foram preparados por método sol-gel a partir do nitrato de ferro e oxicloreto de zircônio à temperatura ambiente. Os sólidos secos foram impregnados com uma solução aquosa de ácido sulfúrico (0,25 e 0,5mol.L-1) e calcinados a 500 e 550°C. Foram preparadas amostras com razões molares Fe/Zr=0,2; 0,4 e 0,8, além dos óxidos puros de ferro e zircônio. Os sólidos foram caracterizados por análise química, espectroscopia no infravermelho com transformada de Fourier, difração de raios X, análise térmica (DTA e TG), medida da área superficial específica, redução termoprogramada, medidas de acidez (TPD de amônia) e espectroscopia fotoeletrônica de raios X.Observou-se a formação das fases tetragonal e monoclínica nas amostras à base de óxido de zircônio, enquanto a hematita foi encontrada nas amostras à base de óxido de ferro. Após a sulfatação dos sólidos, a fase monoclínica desapareceu enquanto a fase tetragonal foi estabilizada. Por outro lado, a hematita não foi afetada pelos íons sulfatos. A presença de ferro no óxido de zircônio também estabilizou a fase tetragonal, independente da presença de sulfato. Nas amostras com razão Fe/Zr=0,8, a hematita foi segregada, co-existindo com a fase tetragonal da zircônia. As áreas superficiais específicas dos sólidos aumentaram pela adição de ferro e foram afetadas pelos íons sulfato, mas nenhuma tendência regular foi observada em função das condições de preparação. O óxido de zircônio mostrou maior capacidade em aceitar e estabilizar íons sulfato na estrutura do que o óxido de ferro. O óxido de zircônio puro foi estável em condições redutoras na faixa de 25-1000°C, mas depois da sulfatação os sólidos perderam espécies sulfatos a 500°C. Os óxidos de ferro, entretanto sofreram redução próxima de 350°C independentemente da presença de íons sulfato. A zircônia pura foi mais ácida do que a hematita pura. A adição de ferro na zircônia não afetou significativamente o número de sítios ácidos, exceto no caso da amostra Fe/Zr(molar)=0,2 calcinada 500°C e tratada com solução 0,25mol.L-1 de ácido sulfúrico. Em geral, os sólidos mais ácidos foram produzidos usando-se estas condições. A zircônia sulfatado possui somente sítios ácidos fortes. Entretanto, a adição de ferro gerou sítios de acidez moderada e este efeito aumentou com a quantidade de ferro nos sólidos. O óxido de ferro produziu sítios de diferentes forças ácidas. A composição superficial também variou com a natureza do sólido e com o método de preparação. Os teores de ferro e enxofre foram mais baixos na superfície do que no volume. Observou-se também que o teor de ferro na superfície dos sólidos diminuiu devido à sulfatação. Entretanto, os sólidos com teores mais elevados de ferro foram capazes de reter mais enxofre na superfície. A melhor condição para se obter sólido ácidos à base de zircônio é preparar preparado pela impregnação do hidróxido de zircônio dopado com ferro (Fe/Zr=0,2), tratado com solução 0,25mol.L-1 de ácido sulfúrico seguido da calcinação a 500°C. Este material possui elevada área superficial (223m2/g), sendo promissor para aplicações catalíticas.
Salvador
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Bi, Melody. "Characterization and Catalytic Properties of Sulfated Zirconia." TopSCHOLAR®, 1996. http://digitalcommons.wku.edu/theses/895.
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Sulfated zirconia has attracted extensive attention due to its superactivity to isomerize alkane and alkenes. Platinum or iron/manganese promoted sulfated zirconia has been shown to increase the reaction rate. These catalysts are normally activated to 650-725°C in air before use. Through on-line analysis of evolved gas species during dynamic heating of the catalysts, some significant information can be obtained concerning the activation mechanism. In the present investigation, combined TG-FTIR, TG-MS and TGDTA techniques were utilized to measure the weight loss of the samples, analyze the evolved gas species and to monitor the phase transformation temperature of the solid. Four samples [(1%) 5% Pt/S04 2-VZr02, 2% Fe/0.5% Mn (iron(III)nitrate, maganese(II) nitrate treated/iron(III) sulfate, maganese(II) sulfate treated)/S04 2-/Zr02] were studied by thermal analysis. Also, the catalytic activity of 0.4% Pt/S04 2-/Zr02 was evaluated the isomerization and oligomerization of 1-hexene. It was found that this type of catalyst has high catalytic activity even at ambient and subambient temperatures.
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Mehta, Shrenik. "Synthesis of a Library of Sulfated Small Molecules." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/2517.
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The discovery of heparin in 1916 resulted in a huge impact on the practice of medicine. Heparin has played a major role in alleviating thrombotic disorders and has also exhibited effects on almost every major system in the human body. Over the past few decades, more and more heparin-protein interactions have come to light. It is implicated to modulate several important processes such as cell growth and differentiation, inflammatory response, viral infection mechanism etc. More interesting is the observation that these interactions are considerably specific with regard to oligosaccharide sequences which have specific spatially oriented sulfate groups modulating the responses. However, due to the complex nature of these interactions and lack of effective computational capabilities, predicting these interactions is challenging.An alternative approach to modulating heparin-protein interactions would be to screen a library of molecules having a diverse distribution of the negative charges and screen them against various proteins of interest to obtain valuable information about the binding/selectivity requirements. This approach would not only yield molecules with potential clinical viability, but may also yield molecules that help decipher native mechanisms regulating proteins, which is called chemical biology in today's terms. Since the difficulties associated with carbohydrate synthesis are well known, well characterized highly sulfated oligosaccharide library screening is considered nearly impossible. Thus, the main aim of this project was to develop an effective method for the synthesis of a library of variably sulfated, non-carbohydrate molecules. The library would contain varying in the number of sulfate groups, offer positional variants of the sulfate groups and provide molecules of varying length so as to afford structural diversity necessary to mimic the heparin sequences. Previous attempts in our laboratory to synthesize such a library encountered two major problems: 1) dimerization of polyphenols due to difficult protection / deprotection strategies and 2) ineffective purification of highly water soluble sulfated molecules. To overcome the problem of protection-deprotection, “click” chemistry has been used in this work for dimerization of polyphenols without any protective groups. To overcome the second problem, a non-aqueous method of purification of highly sulfated molecules was developed, which is the first such report.As a proof of concept, a small library of 14 sulfated monomers and dimers and 8 non-sulfated dimers was generated. The protocol for dimerization of free polyphenolic molecules in has been established to use “click” chemistry for coupling the monomers without the need to protect the free hydroxyl groups. Thus by circumventing the inefficient protection-deprotection protocol, there is a tremendous improvement in yields, ease of purification and characterization and greater productivity allowing the synthesis of more number of molecules in a relatively shorter span of time. By masking the charge of the sulfate using an appropriate counter-ion and owing to the inherent lipophilicity of the aromatic scaffold, these highly charged molecules could be purified using normal phase silica gel chromatography. This method reduced the purification time from previous over 48 hours with the aqueous method to approximately 15 minutes. Further, this purification protocol may be possibly automated so as to truly generate a large library of variably sulfated non-carbohydrate molecules for the first time. Screening this library of 22 sulfated and unsulfated molecules against three enzymes of the coagulation cascade – factors IIa, Xa and XIa – has provided a wealth of information with regard to engineering specificity for recognition of these enzymes. The screening led to the identification of CS3 which inhibited factor XIa with an IC 50 of ~ 5 μM and other enzymes with an IC 50 of > 500 μM as a lead candidate with high selectivity. The success of this strategy bodes well for understanding the heparin-protein interactions at a molecular level. Previous attempts in our laboratory to synthesize such a library encountered two major problems: 1) dimerization of polyphenols due to difficult protection / deprotection strategies and 2) ineffective purification of highly water soluble sulfated molecules. To overcome the problem of protection-deprotection, “click” chemistry has been used in this work for dimerization of polyphenols without any protective groups. To overcome the second problem, a non-aqueous method of purification of highly sulfated molecules was developed, which is the first such report.As a proof of concept, a small library of 14 sulfated monomers and dimers and 8 non-sulfated dimers was generated. The protocol for dimerization of free polyphenolic molecules in has been established to use “click” chemistry for coupling the monomers without the need to protect the free hydroxyl groups. Thus by circumventing the inefficient protection-deprotection protocol, there is a tremendous improvement in yields, ease of purification and characterization and greater productivity allowing the synthesis of more number of molecules in a relatively shorter span of time. By masking the charge of the sulfate using an appropriate counter-ion and owing to the inherent lipophilicity of the aromatic scaffold, these highly charged molecules could be purified using normal phase silica gel chromatography. This method reduced the purification time from previous over 48 hours with the aqueous method to approximately 15 minutes. Further, this purification protocol may be possibly automated so as to truly generate a large library of variably sulfated non-carbohydrate molecules for the first time. Screening this library of 22 sulfated and unsulfated molecules against three enzymes of the coagulation cascade – factors IIa, Xa and XIa – has provided a wealth of information with regard to engineering specificity for recognition of these enzymes. The screening led to the identification of CS3 which inhibited factor XIa with an IC 50 of ~ 5 ?M and other enzymes with an IC 50 of > 500 ?M as a lead candidate with high selectivity. The success of this strategy bodes well for understanding the heparin-protein interactions at a molecular level.
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Abdelfadiel, Elsamani I. "INVESTIGATION OF ANTICOAGULATION PROPERTIES OF SULFATED GLYCOSAMINOGLYCAN MIMETICS." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/5054.
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Abstract
INVESTEGATION OF ANTICOAGULATION PROPERTIES OF SULFATED
GLYCOSAMINOGLYCAN MIMETICS
By Elsamani Ismail Abdelfadiel, MS
A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Science at Virginia Commonwealth University
Virginia Commonwealth University, 2017.
Supervisor: Umesh R Desai
Professor, Department of Medicinal Chemistry
The existence of thrombosis in numerous pathophysiological situations formed a vast necessity for anticoagulation therapy. Thrombin and factor Xa are the only two factors of the entire coagulation cascade that have been major targets for regulation of clotting via the direct and indirect mechanism of inhibition. Our recent discovery of sulfated non-saccharide glycosaminoglycan mimetics, especially G2.2, that demonstrates highly selective cancer stem-like cells (CSCs) inhibition activity. G2.2 inhibited the growth of CSCs from multiple cancer cell lines.
To evaluate its in vivo anticoagulation effect, we asked a contract research organization (CRO) to produce 20 g of material, labelled as G2.2Y. Evaluation of G2.2C in HT-29 xenograft mouse model showed a significant reduction in tumor volume and CSC markers, but unexpected bleeding consequences in some animals were observed. Also in a tail bleeding experiment, G2.2Y showed a significant enhancement in bleeding volume. Comparable studies with G2.2 synthesized in our laboratory had shown no bleeding effects. To investigate the difference between the two G2.2 samples (G2.2W (white) and G2.2Y (Yellow) that were performed using UPLC-MS characterization, we were able to determine that the G2.2Y sample was an 85:15 blend of two compounds. Elemental, NMR and MS data revealed that G2.2W was fully sulfated flavonoid derivative, as expected, but G2.2Y contained one less sulfate group. We tested both agents for their inhibition of various coagulation factors and revealed that G2.2Y inhibited fXIa nearly 2-fold better in comparison to G2.2W. Furthermore, activated partial thromboplastin time assay (APTT) indicated that G2.2W exhibited almost 3-4-fold less anticoagulant activity compared to G2.2Y. This indicates that the loss of just one sulfate group could induce substantial side effects and lead to a discovery of new anticoagulant agent. Such structure–activity relationship is important to understand if the in vivo metabolism of the agents leads to accumulation of de-sulfated products.
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Macedo, Ana AngÃlica Mathias. "Collagen - sulfated polysaccharide films with antithrombogenic properties: preparation and characterization." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7709.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoFundaÃÃo de Amparo à Pesquisa do Estado do CearÃ
This work reports the preparation and characterization of collagen-sulfated polysaccharide films and applications in coating of cardiovascular prostheses. The films were prepared by adding the sulfated polysaccharide solution on soluble collagen (0, 5, 10, 20 and 25 %). The blends of collagen-sulfated polysaccharide were casted in acrylic molds, and dried at low temperature. The physico-chemical properties of collagen-sulfated polysaccharide films, were studied using infrared spectroscopy that showed absorptions typical of collagen and sulphated polysaccharide; the thermal analysis (DSC) showed that the structural integrity of collagen was unmodified during the extraction process and the polysaccharide present in the samples did not decrease the thermal stability of the collagen, which was higher for the concentrations of 20 %. In the thermal analysis (DTG), the addition of the polysaccharide caused a small decrease of the stability of thermal degradation and when was adding 5 % of the sulfated polysaccharide to the collagen, a reduction in its stability occurs, however, in the concentrations of 10, 20 and 25 %, the stability of thermal degradation of the film increased. In the impedance spectroscopy, the results are associated possibly, to the interactions between the macromolecules. The blood compatibility was analyzed by platelet adhesion and the results showed that the films possess hemocompatibility and antitrombogenic properties.
Este trabalho aborda sobre o preparo e a caracterizaÃÃo de filmes de colÃgeno-polissacarÃdeo sulfatado e sua aplicaÃÃo para revestimento de prÃteses vasculares. Os filmes foram obtidos a partir da mistura de soluÃÃo de colÃgeno e polissacarÃdeo sulfatado, nas concentraÃÃes 0, 5, 10, 20 e 25 % do polissacarÃdeo. As soluÃÃes de colÃgeno-polissacarÃdeo sulfatado foram formatadas em moldes de acrÃlico em condiÃÃes de baixa umidade e temperatura. A caracterizaÃÃo fÃsico-quÃmica dos filmes de colÃgeno-polissacarÃdeo sulfatado foi estudada por espectrometria no infravermelho que mostraram bandas tÃpicas do colÃgeno e bandas tÃpicas do polissacarÃdeo sulfatado; a anÃlise tÃrmica por DSC mostra que a integridade estrutural do colÃgeno foi preservada no processo de extraÃÃo e que a adiÃÃo do polissacarÃdeo nas amostras nÃo diminuiu a estabilidade tÃrmica do colÃgeno tendo sido maior na concentraÃÃo de 20 %. Na anÃlise tÃrmica por DTG, a adiÃÃo do polissacarÃdeo causa um pequeno decrÃscimo da estabilidade de degradaÃÃo tÃrmica e ao adicionarmos 5 % do polissacarÃdeo sulfatado ao colÃgeno, ocorre uma reduÃÃo em sua estabilidade, porÃm, a partir daÃ, nas concentraÃÃes 10, 20 e 25 %, a estabilidade de degradaÃÃo tÃrmica do filme vai aumentando. Na espectroscopia de impedÃncia, os resultados estÃo associados, possivelmente, a interaÃÃes entre as macromolÃculas. A compatibilidade sangÃÃnea foi analisada por adesÃo de plaquetas e os resultados mostraram que os filmes possuem hemocompatibilidade e propriedades antitrombogÃnicas.
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Li, Xuebing. "Butane skeletal isomerization on sulfated zirconia at low temperature." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972215158.
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Henry, Brian Lawrence. "Novel Sulfated 4-Hydroxycinnamic Acid Oligomers as Potent Anticoagulants." VCU Scholars Compass, 2007. http://scholarscompass.vcu.edu/etd/1462.
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The occurrence of thrombosis in several pathophysiological conditions creates a huge need for anticoagulation therapy. Thrombin and factor Xa have been prime targets for regulation of clotting through the direct and indirect mechanism of inhibition. This work investigates chemo-enzymatically prepared oligomers of 4-hydroxycinnamic acids (DHPs) as potential anticoagulants. Oligomers were prepared through peroxidase-catalyzed oxidative coupling of 4-hydroxycinnamic acids. The products resulting from this reaction are called CDs, FDs and SDs. Structurally, these sulfated DHPs are unique and do not resemble any of the anticoagulants known in the literature.DHP oligomers were found to increase clotting times at concentrations comparable to heparin. Studies in blood and plasma show that DHPs possess an anticoagulation profile similar to enoxaparin. To understand the mechanism of action of DHPs, we studied the inhibition of thrombin, FXa, FIXa, and FVIIa in the presence and absence of antithrombin. CDs and FDs display a preference for direct inhibition of thrombin and FXa, and exhibit a high level of specificity over FIXa and FVIIa. In the presence of AT, CDs and FDs displayed weaker inhibition of FXa and thrombin suggesting that binding to AT is a competitive side reaction. SDs exhibited potent inhibition of FXa and thrombin in the absence of antithrombin, but was inactive against FIXa and FVIIa representing the best selectivity among the DHPs. For SDs, inhibition of all the pro-coagulant enzymes favored the antithrombin dependent pathway. Binding studies were performed to determine how CDs directly inhibits thrombin. Competitive binding studies suggest that CDs interacts with exosite II and disrupts the catalytic triad of thrombin. These results indicate that the preferred mechanism of CDs action is exosite II mediated allosteric disruption of thrombin. CDs appears to be the first exosite II mediated DTI and this represents a novel mechanism of inhibitor function. The inhibition characteristics of DHPs are unique and radically different in structure from all the current clinically used anticoagulants. To the best of our knowledge this dual mechanism of anticoagulation and unique binding mode has not been described as yet in literature and represents a novel strategy that our laboratory has discovered.
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Ferraro, Magda [Verfasser]. "Biodegradable Sulfated Dendritic Nanocarriers for Biomedical Applications / Magda Ferraro." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1213295025/34.
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Degirmenci, Volkan. "Methane Activation Via Bromination Over Sulfated Zirconia/sba-15 Catalysts." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12609021/index.pdf.
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Methane activation with bromine followed by the condensation of the methyl bromide into higher hydrocarbons or oxygenates is a novel route. However, the selective production of monobrominated methane (CH3Br) at high conversions is a crucial prerequisite. A reaction model was developed according to the kinetic data available in the literature and thoroughly studied to investigate the optimum reactor conditions for selective methane bromination in gas phase. It was concluded that at high methane (>90%) conversions dibromomethane synthesis was favored at high selectivity (~90%) under the following conditions: T=330 °
C, Br:CH4 = 3. Sulfated zirconia included SBA-15 catalysts were prepared and characterized for the catalytic methane activation via bromination. The SBA-15 sol-gel preparation technique was followed and the zirconium was added during the preparation in the form of ZrOCl2·
8H2O with 5-30 mol % ZrO2 with respect to the SiO2 content simultaneously with the silicon source (TEOS). The catalysts were sulfated in 0.25 M H2SO4 solution. The zirconium contents of the catalysts were determined by elemental analysis and 15 wt. % Zr was determined as the highest amount. XRD analysis showed the crystalline zirconia peaks only for high zirconia loadings (>
25 mol % ZrO2) indicating the good distribution of Zr in silica framework at lower loadings. BET surface areas of the sulfated catalysts are in the range of 313-246 m2/g. The porous structures of the catalysts were determined by TEM pictures, which revealed that the increase in Zr content decreased the long range order of pore structure of SBA-15 in agreement with XRD results. The acidities of the catalysts were determined by 1H MAS NMR experiments. Brø
nsted acidity was identified by a sharp 1H MAS NMR line at 10.6 ppm. The highest acidity was observed at 5.2 wt. % Zr loading according to 1H MAS NMR experiments. 29Si MAS NMR analysis showed the formation of Si-O-X linkages (X=H, Zr). Further characterization of Brø
nsted acidity was performed by FT-IR spectroscopy of adsorbed CO at 82 K. The analysis revealed that the Brø
nsted acidity of sulfated catalysts were similar to the acid strength of the conventional sulfated zirconia. In TPD experiments, the basic molecule isopropylamine (IPAm) was adsorbed and decomposition temperature of IPAm was monitored. The temperature decreased from 340 °
C to 310 °
C in sulfated catalysts, indicating the acidic character of these samples. Catalytic methane bromination reaction tests were performed in a quartz tubular reactor. The results showed that 69% methane conversion was attainable over SZr(25)SBA-15 catalyst at 340 °
C. The liquid 1H NMR measurements of the products revealed that >
99% methyl bromide selectivity was achieved.
Books on the topic "Sulfated"
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Chondroitin sulfate: Structure, role and pharmacological activity. Amsterdam: Elsevier, 2006.
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Barton, Larry L., ed. Sulfate-Reducing Bacteria. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1582-5.
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Skalny, Jan. Sulfate Attack on Concrete. London: Taylor & Francis Group Plc, 2004.
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J, Marchand, and Odler Ivan 1930-, eds. Sulfate attack on concrete. New York: Spon, 2001.
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Clifton, James R. Sulfate diffusion in concrete. Gaithersburg, MD: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1994.
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J, Marchand, and Odler Ivan 1930-, eds. Sulfate attack on concrete. New York: Spon, 2002.
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Petrus Antonius Maria van der Klein. Cyclic sulfates in carbohydrate chemistry. s'-Gravenhage: Pasmans Offsetdrukkerij BV, 1992.
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Fricke, Arthur L. Physical properties of kraft black liquor: Interim report, phase II. Washington, D.C: [U.S. Dept. of Energy, Office of Scientific and Technical Information], 1985.
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Majmundar, Hasmukhrai H. Mineral commodity report, sodium sulfate. Sacramento, Calif: California Dept. of Conservation, Division of Mines and Geology, 1985.
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Acid sulfate soils in Malaysia. Serdang: Universiti Putera Malaysia Press, 2006.
Find full textBook chapters on the topic "Sulfated"
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Gooch, Jan W. "Sulfated Oil." In Encyclopedic Dictionary of Polymers, 711. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_11383.
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Bährle-Rapp, Marina. "Sulfated Castor Oil." In Springer Lexikon Kosmetik und Körperpflege, 538. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_10197.
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Bährle-Rapp, Marina. "Sulfated Glyceryl Oleate." In Springer Lexikon Kosmetik und Körperpflege, 538. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_10198.
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Bährle-Rapp, Marina. "Sulfated Olive Oil." In Springer Lexikon Kosmetik und Körperpflege, 538. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_10199.
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Bährle-Rapp, Marina. "Sulfated Peanut Oil." In Springer Lexikon Kosmetik und Körperpflege, 538. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_10200.
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Morva, Ágnes, Éva Fenyvesi, Natascha Roos, Béla Zsadon, and József Szejtli. "Sulfated Cyclodextrin Derivatives." In Proceedings of the Ninth International Symposium on Cyclodextrins, 53–56. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4681-4_12.
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Li, Tianlu, Peng Peng, and Xuefei Huang. "Sulfated Glycoprotein Synthesis." In Methods in Molecular Biology, 1–17. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2489-0_1.
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Inácio, Ana Rita, Ana C. Carvalho, Catarina Oliveira, Lara Reys, Simone S. Silva, Nuno M. Neves, Albino Martins, Rui L. Reis, and Tiago H. Silva. "Sulfated Seaweed Polysaccharides." In Polysaccharides of Microbial Origin, 1–34. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-35734-4_17-1.
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Inácio, Ana Rita, Ana C. Carvalho, Catarina Oliveira, Lara Reys, Simone S. Silva, Nuno M. Neves, Albino Martins, Rui L. Reis, and Tiago H. Silva. "Sulfated Seaweed Polysaccharides." In Polysaccharides of Microbial Origin, 307–40. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-42215-8_17.
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Casu, Benito, Annamaria Naggi, and Giangiacomo Torri. "Synthesis of Sulfated Glycosaminoglycans." In Glycoscience: Chemistry and Chemical Biology I–III, 1895–903. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56874-9_45.
Full textConference papers on the topic "Sulfated"
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Schick, K. P., S. Shapiro, G. Tuszynski, and J. Slawek. "SULFATIDES AND GLYCOLIPIDS IN PLATELETS AND ENDOTHELIAL CELLS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643641.
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Sulfatides are sulfated glycolipids which are negatively charged and thought to influence receptor mediated activities. Sulfatides have the capacity to provide a surface for the initiation of in vitro coagulation tests and these acidic lipids represent the potential biological surface for the initiation of the contact and intrinsic systems in vivo. Several sulfatides have been demonstrated in blood platelets. We have investigated sulfatides and other glycolipids in endothelial cells and platelets in order to define the cellular sources for sulfatides that would be available for influencing hemostasis. Endothelial cells were derived from primary cultures of human umbilical veins and human platelets were obtained from freshly-collected blood. Cellular lipids were extracted by the Folch method. Sulfatides and glycolipids were purified by silicic acid chromatography, separated by thin-layer chromatography, and quantitated by the assay of sphingosine. Glycolipids were also analyzed by HPLC. Globoside was found to be the predominant glycolipid in endothelial cells while lactosyl ceramide was the predominant glyco-lipid in platelets. Sulfatides were detected by two approaches: 1) Sulfatide synthesis by the incorporation of [35S]-Sulfate; 2) The specific binding of [125I]-thrombospondin and [125I]-von Willebrand’s factor (vWF) to sulfatides separated by thin-layer chromatography (TLC). Several sulfatides were identified in endothelial cells and platelets by virtue of the incorporation of [35S]-sulfate into glycolipids separated by TLC. [125I]-TSP and [125I]-vWF bound to the glycolipids that had incorporated [35S]-sulfate. [35S]-sulfate was primarily incorporated into sulfated galactosyl ceramide but both cells also synthesized complex glycolipids. TSP and vWF were shown to bind to sulfated galactosyl ceramide, a band that comigrated with glycosyl ceramide as well as with two more complex sulfatides in both cells. However, differences in sulfatide synthesis and binding of TSP to sulfatides were observed in endothelial cells from that in platelets. The study indicates that endothelial cells and platelets contain several sulfatides and thus are potential sources for sulfatides for the initiation of coagulation.
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Casu, B., L. Marchese, A. Naggi, G. Torri, J. Fareed, A. Racanelli, and J. M. Walenga. "INFLUENCE OF THE SULFATION PATTERN ON CERTAIN BIOLOGICAL PROPERTIES OF GALACTOSAMINOGLYCANS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643251.
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In order to investigate the influence of charge distribution and chain length on the biological properties of sulfated polysaccharides, additional sulfate groups were introduced into the galactosaminoglycans, chondriotin sulfate and dermatan sulfate. Using a flexible method (with sulfuric acid and chlorosulfonic acid) for concurrent sulfation and controlled depolymerization, numerous products were obtained and characterized by chemical, enzymatic and nuclear magnetic resonance spectroscopic methods. The biologic actions of these products were profiled in both in vitro and in vivo assays for antithrombotic activity. Despite a weaker in vitro anticoagulant activity, low molecular weight over sulfated galactosaminoglycans produced significant dose-dependent antithrombotic actions in animal models which were similar to the actions observed with oversulfated low molecular weight heparins. These results suggest that a significant antithrombotic activity can be elicited through non-specific interactions of polysulfates with cellular and plasma components, and that clusters of sulfate groups such as the 4-6 disulfate group on D-galactosaminoglycan residues may be important for these interactions. Furthermore, these results, also suggest that supersulfation of glycosaminogly-cans results in products with biologic activity distinct from the native material.
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Sappok, Alexander, Sean Munnis, and Victor W. Wong. "Individual and Synergistic Effects of Lubricant Additive Components on Diesel Particulate Filter Ash Accumulation and Performance." In ASME 2012 Internal Combustion Engine Division Spring Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ices2012-81237.
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The current CJ-4 oil specification places a limit on the oil’s sulfated ash content of 1.0% to reduce the build-up of lubricant-derived ash in the diesel particulate filter (DPF). Lubricant additives, specifically detergents and anti-wear additives, contribute to most of the sulfated ash content in the oil and ash accumulation in the DPF, and hence are studied with increasing interest in the optimization of the combined engine-oil-aftertreatment system. However, characteristics of ash deposits found in the particulate filter, which are affected by a number of parameters, differ markedly from those of the ASTM-method defined sulfated ash. In addition, ash characteristics and effects on DPF performance vary substantially among the different metallic base in the additives, specifically calcium, magnesium, and zinc. Through a series of carefully-controlled tests with specially-formulated lubricant additives, this work quantified the individual and combined effects of the most common detergent and anti-wear additives on the ash properties which directly influence DPF pressure drop. The results show that different lubricant additive formulations (Ca, Zn, Mg) produce profound differences in DPF pressure drop. It was found that DPF ash is a complex mixture of metals (Ca, Zn, Mg) in the form of sulfates, phosphates, and oxides. These ash compounds each have unique physical properties, which affect DPF pressure drop differently. In particular, ash containing calcium sulfate compounds resulted in an increase in filter pressure drop by over a factor of two, relative to the same amount of ash composed only of zinc phosphate or magnesium oxide compounds, at the same ash loading in the DPF. In addition, synergistic effects due to specific additive combinations were also explored and showed significant differences in ash composition and degree of exhaust flow restriction imposed by the ash resulting from specific additive combinations, as opposed to the individual additives themselves. Results are useful not only for lubricant formulators to design oils for improved aftertreatment system compatibility, but also to understand the practical effects of ash in the DPF in relation to the standardized sulfated ash definition in the lubricant specification.
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Benjes, Paul A., Manfred Dromowicz, George C. Slim, and Olga V. Zubkova. "SYNTHESIS OF DI-SULFATED DI- AND TRISACCHARIDE DERIVATIVES RELATED TO CHONDROITIN SULFATE." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.659.
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Chen, Quan, Subhash Ayirala, and Ali Yousef. "A Critical Review of Low Salinity Water Flooding for Offshore Applications and Potential Opportunities." In SPE Conference at Oman Petroleum & Energy Show. SPE, 2022. http://dx.doi.org/10.2118/200237-ms.
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Abstract Low salinity water flooding (LSWF) is an emerging enhanced oil recovery (EOR) technology with enormous potential for offshore applications. Numerous laboratory experiments and field trials of LSWF have been conducted to evaluate the EOR benefits and understand the underlying recovery mechanisms. The objective of this study is to provide a critical review on LSWF offshore field applications and summarize the key lessons learned. A review was also conducted on the capabilities of existing sulfate removal units for seawater injection in offshore fields. Furthermore, the potential of targeting offshore oil fields with de-sulfated seawater injection, either ongoing or planned, as primary candidates to switch over to LSWF EOR has been investigated. For LSWF field trials, the chance of success can be significantly improved when it is based on key laboratory screening tests such as corefloods at reservoir conditions. The methodologies implemented for LSWF offshore field trials mainly involved Single Well Chemical Tracer Test (SWCTT) and inter-well field trials. However, the inter-well field trials implemented so far are restricted to unconfined pilots, which makes the production and injection allocation more difficult. Therefore, confined pilots are recommended for future consideration of LSWF field trials to provide better estimations on swept volume and improvements in the oil displacement efficiency. Globally, there are more than 80 sulfate removal units currently in operation for offshore seawater flooding with approximately 10 million BWPD of cumulative de-sulfated seawater injection (DSSW) capacity for offshore water floods in the North Sea, the Gulf of Mexico, West Africa, and Brazil. All these fields with DSSW injection either ongoing or planned can become potential candidates to switch to LSWF EOR for the following two reasons: (1) The primary purpose for sulfate removal from sea water is to prevent scaling due to often high concentration of divalent cations in formation water and high sulfate concentration in seawater. The divalent cations can act as bridges between negatively charged rock surfaces and negatively charged polar oil components to increase the oil-wet tendency. These bridges become primary targets to be replaced by un-complexed cations in low salinity water for EOR. (2) The de-sulfated sea water injection process can easily be switched to LSWF by replacing the existing nanofiltration membranes in the sulfate removal facilities with reverse osmosis membranes and upgrading the facilities to increase the water treatment capacity and generate the desired low salinity water if these reservoirs fit the screening criteria and have a positive outcome of LSWF evaluation. Such retrofitting to the seawater treatment facilities on offshore platforms can bring significant gains to increase oil recovery with minimal additional investment. The novelty of this study is that it provides some useful practical guidelines for reservoir screening and offshore field implementation of LSWF. Also, the new potential of evaluating the offshore oil fields with existing de-sulfated seawater injection for switching over to LSWF has been identified. These findings will have a potential impact on increasing the prospects and opportunities of LSWF for EOR in different offshore fields.
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Schick, B. P., C. J. Walsh, and T. Jenkins-West. "PROTEOGLYCANS AND SULFATED PROTEINS OF PLATELETS: CHARACTERIZATION AND RESPONSE TO THROMBIN AND ADP." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643642.
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The proteoglycans (PG) and sulfated proteins of guinea pig platelets were labeled in vivo by intraperitoneal injection of (35S)sulfate. At 3 days after injection, platelets contained 3 distinct populations of chondroitin-6-sulfate proteoglycans which together constitute about 65% of the cellular (35S) label. Most PG elute from a DEAE-Sephacel column with 4M Gdn HC1 (PG-1, 87%), and elute at Kav 0.12 on Sepharose CL-6B. The PG-1 can be resolved by SDS-PAGE into two fractions. The remainder (PG-2, 13%) elutes from the DEAE-Sephacel column with 4M Gdn HCl/2% Triton X-100 or 2% CHAPS, and has a Kav of 0.07 on Sepharose CL-6B. About 20-25% of the cell (35S) label elutes from DEAE-Sephacel in the wash-through or with 0.23M NaCl, and can be resolved by SDS-PAGE into at least 8 distinct bands which we have tentatively characterized as sulfated glycoproteins. The remainder of the (35S) is in low molecular weight (LMW) material which does not adhere to DEAE-Sephacel and has not been further characterized.Platelets were treated with either thrombin or ADP, and the cells were then separated from the supernatant by centrifugation. The radiolabeled molecules in the supernatant and the cells were analyzed by DEAE-Sephacel and Sepharose CL-6B column chromatography. About 65% of the total cell (35S) was released from the cells by thrombin. Most of this radiolabel adhered to the DEAE-Sephacel column, and was found to be PG-1. The remainder of the released (35S) was about half the LMW material. In contrast, only 10-15% of the (35S)labeled material retained by the cells adhered to DEAE-Sephacel and was found to be PG-2. The remainder of the (35S)-labeled material retained by the platelets was the sulfated proteins and the LMW material. ADP caused release of about 15% of the (35S), and this was found to be in part PG-1 and in part the LMW material, but not PG-2. None of the (35S)-labeled molecules appeared to be degraded during platelet activation. We suggest that the PG-1 represent the a-granule and PG-2 the membrane proteoglycans. The sulfated proteins have not been described previously. Their role is not known, but we hypothesize that they may form part of the negative charge of the glycocalix and thus be part of the reactive surface of the platelet.
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YANG, HUA, and RONG LU. "SOLID SUPERACIDS OF SULFATED ZIRCONIA-SILICON NANOCRYSTALS." In Proceedings of the International Symposium on Solid State Chemistry in China. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776846_0069.
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Zhao, Jun, Shu-Qing Wu, and Bing-Xu Liu. "Studies on sulfated modification of Cordyceps polysaccharide." In 2011 International Conference on New Technology of Agricultural Engineering (ICAE). IEEE, 2011. http://dx.doi.org/10.1109/icae.2011.5943918.
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"Chemistry Composition and Properties of Sulfated Cements." In SP-326: Durability and Sustainability of Concrete Structures (DSCS-2018). American Concrete Institute, 2018. http://dx.doi.org/10.14359/51711009.
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"Corrosion-Resistant Cements Based on Sulfated Clinkers." In SP-326: Durability and Sustainability of Concrete Structures (DSCS-2018). American Concrete Institute, 2018. http://dx.doi.org/10.14359/51711013.
Full textReports on the topic "Sulfated"
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Berkowitz, Jacob, and Christine VanZomeren. Approaches to identify and monitor for potential acid sulfate soils in an ecological restoration context. Engineer Research and Development Center (U.S.), February 2022. http://dx.doi.org/10.21079/11681/43349.
Full textAbstract:
Potential acid sulfate soils include materials with the capacity to generate acidity under certain environmental conditions. As such, these soils can pose challenges to ecological restoration projects occurring in wetlands and nearshore environments. To provide guidance for ecosystem restoration practitioners, the following technical note describes acid sulfate soil formation and distribution and then describes techniques for identifying and monitoring acid sulfate soil conditions prior to and following implementation of restoration activities. Finally, this technical note outlines a number of tools and recently published resources to help avoid unintended consequences of acid sulfate soil disturbance and achieve ecological restoration objectives.
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Branam, Tracy, Robin Green, Oliver Wittman, and Anne Ayre. Sulfates in Indiana Substrates. Purdue University, December 2016. http://dx.doi.org/10.5703/1288284316342.
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Ponnersheim, James M. Sulfate diffusion in concrete. Gaithersburg, MD: National Institute of Standards and Technology, 1994. http://dx.doi.org/10.6028/nist.ir.5361.
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Kingston, A. W., O. H. Ardakani, G. Scheffer, M. Nightingale, C. Hubert, and B. Meyer. The subsurface sulfur system following hydraulic stimulation of unconventional hydrocarbon reservoirs: assessing anthropogenic influences on microbial sulfate reduction in the deep subsurface, Alberta. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330712.
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Hydraulic fracturing is a reservoir stimulation technique that involves the injection of high-pressure fluids to enhance recovery from unconventional hydrocarbon reservoirs. Often this involves the injection of surface waters (along with additives such as biocides) into formational fluids significantly different isotopic and geochemical compositions facilitating geochemical fingerprinting of these fluid sources. In some instances, the produced fluids experience an increase in hydrogen sulfide (H2S) concentration over the course of production resulting in an increased risk to health and safety, the environment, and infrastructure due to the toxic and corrosive nature of H2S. However, questions remain as to the origin and processes leading to H2S formation following hydraulic fracturing. In this study, we analyzed a series of produced waters following hydraulic fracturing of a horizontal well completed in the Montney Formation, Western Canada to evaluate variations in geochemical and microbiological composition over time and characterize potential sulfur species involved in the production of H2S. Initially, sulfur isotope ratios (d34S, VCDT) of dissolved sulfate in produced water had a baseline value of 27per mil similar to the d34S value of 25per mil for solid anhydrite derived from core material. Subsequently, d34S values of sulfate in produced fluids sequentially increased to 35per mil coincident with the appearance of sulfides in produced waters with a d34SH2S value of 18per mil. Oxygen isotope values of dissolved sulfate exhibited a synchronous increase from 13.2per mil to 15.8per mil VSMOW suggesting sulfate reduction commenced in the subsurface following hydraulic fracturing. Formation temperatures are <100°C precluding thermochemical sulfate reduction as a potential mechanism for H2S production. We suggest that microbial reduction of anhydrite-derived sulfate within the formation is likely responsible for the increase in H2S within produced waters despite the use of biocides within the hydraulic fracturing fluids. Initial assessments of microbial communities indicate a shift in community diversity over time and interactions between in situ communities and those introduced during the hydraulic fracturing process. This study indicates that biocides may not be fully effective in inhibiting microbial sulfate reduction and highlights the role anthropogenic influences such as hydraulic fracturing can have on the generation of H2S in the subsurface.
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Merrill, R. A., K. F. Whittington, and R. D. Peters. Vitrification of high sulfate wastes. Office of Scientific and Technical Information (OSTI), September 1994. http://dx.doi.org/10.2172/10107401.
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Kalensky, M., S. Chemerisov, A. J. Youker, A. Hebden, P. Tkac, V. Makarashvili, E. Krahn, et al. Radio of Nitrate and Sulfate Solutions. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1130737.
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Liseroudi, M. H., O. H. Ardakani, P. K. Pedersen, R. A. Stern, J M Wood, and H. Sanei. Diagenetic and geochemical controls on H2S distribution in the Montney Formation, Peace River region, western Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329785.
Full textAbstract:
The Lower Triassic Montney Formation is a major siltstone dominated unconventional tight gas play in the Western Canadian Sedimentary Basin (WCSB). In the Peace River region, the Montney Formation contains a regionally variable amount of hydrogen sulfide (H2S) in gas-producing wells with western Alberta's wells having the highest concentrations. Previous studies on the source and distribution of H2S in the Montney Formation mainly focused on variations of H2S concentration and its relationship with other hydrocarbon and non-hydrocarbon gases, sulfur isotope composition of H2S, as well as organo-sulfur compounds in the Montney Formation natural gas. None of those studies, however, focused on the role of diagenetic and geochemical processes in the formation of dissolved sulfate, one of the two major ingredients of H2S formation mechanisms, and pyrite within the Montney Formation. According to the results of this study, the Montney Formation consists of two different early and late generations of sulfate minerals (anhydrite and barite), mainly formed by the Montney Formation pore water and incursion of structurally-controlled Devonian-sourced hydrothermal sulfate-rich fluids. In addition, pyrite the dominate sulfide mineral, occurred in two distinct forms as framboidal and crystalline that formed during early to late stages of diagenesis in western Alberta (WAB) and northeast British Columbia (NEBC). The concurrence of the late-stage anhydrite and barite and various types of diagenetic pyrite with high H2S concentrations, particularly in WAB, their abundance, and spatial distribution, imply a correlation between the presence of these sulfate and sulfide species and the diagenetic evolution of sulfur in the Montney Formation. The sulfur isotope composition of anhydrite/barite, H2S, and pyrite demonstrates both microbial and thermochemical sulfate reduction (MSR and TSR) controlled the diagenetic sulfur cycle of the Montney Formation. The relationship between the delta-34S values of the present-day produced gas H2S and other sulfur-bearing species from the Montney and other neighboring formations verifies a dual native and migrated TSR-derived origin for the H2S gas with substantial contributions of in situ H2S in the Montney reservoir.
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Bliss, Mary. Gaseous Sulfate Solubility in Glass: Experimental Method. Office of Scientific and Technical Information (OSTI), November 2013. http://dx.doi.org/10.2172/1113600.
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Martin, P. F. C., and R. O. Lokken. Characterization of phosphate/sulfate waste grout cores. Office of Scientific and Technical Information (OSTI), September 1993. http://dx.doi.org/10.2172/10191613.
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Kalensky, Michael, Thomas Brossard, Peter Tkac, and Sergey Chemerisov. Fission Induced Radiolysis of Uranyl Sulfate Solutions. Office of Scientific and Technical Information (OSTI), September 2021. http://dx.doi.org/10.2172/1824778.
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