Search results for "Uronic Acids"
showing 10 items of 26 documents
Isolation and partial characterization of uronic acid-containing glycoproteins from Mucor rouxii.
1995
Five different fractions containing uronic acids associated with protein were isolated from the cytoplasm of the filamentous form of Mucor rouxii. A signle fraction was isolated from the cell wall by hot sodium dodecyl sulfate followed by ion exchange column chromatography. Two cytoplasmic entities (peaks I and II) were not adsorbed to DEAE Bio-Gel A. The molecular mass of peaks I to V ranged from 16.5 to 210 kDa. The protein-uronic acid ratios were different for each fraction. The cell wall fraction showed a molecular mass of 16.5 kDa, similar to that of peak II but with differences in chromatographic behavior and protein-uronic acid ratio. The possible role of these molecules as acceptors…
Pb(II) adsorption by a novel activated carbon - alginate composite material. A kinetic and equilibrium study.
2016
The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) has been tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ion from aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strength range 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was used to check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic (pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich) models were used to fit experimental data, and were statistically compared. Calcium alginate …
Tuning the Structure of Galacturonate Hydrogels: External Gelation by Ca, Zn, or Fe Cationic Cross-Linkers
2019
International audience; We show here how the nature of various divalent cations M2+ (Ca2+, Zn2+, or Fe2+) influences the structure and mechanical properties of ionotropic polygalacturonate (polyGal) hydrogels designed by the diffusion of cations along one direction (external gelation). All hydrogels exhibit strong gradients of polyGal and cation concentrations, which are similar for all studied cations with a constant ratio R = [M2+]/[Gal] equal to 0.25, showing that every M2+ cation interacts with four galacturonate (Gal) units all along the gels. The regions of the hydrogels formed in the early stages of the gelation process are also similar for all cations and are homogeneous, with the s…
A new neuraminic acid derivative and three types of glycopeptides isolated from the Cuvierian tubules of the sea cucumber Holothuria forskali
1973
The Cuvierian tubules of Holothuria forskali Della Chiaje, a sea cucumber found in the Adriatic Sea, were investigated with regard to their carbohydrate moieties. From a Pronase digest of these tubules three types of carbohydrate units were isolated and characterized. 1. A high-molecular-weight glycopeptide fraction was shown to contain sulphated polyfucose, galactosamine, a uronic acid and a previously unknown neuraminic acid derivative. The sulphate was shown by i.r. analysis to be present as an O-ester. The carbohydrate unit was linked O-glycosidically to threonine and serine residues in the polypeptide chain. The hitherto unknown neuraminic acid derivative (Hf-neuraminic acid) was resis…
The amide of galacturonic acid with lysine as an immunodominant component of the lipopolysaccharide core region from Proteus penneri 42 strain
2014
Most Proteus lipopolysaccharides (LPSs) contain uronic acids or their amides with different amino acids, which together with other negatively charged components account for the acidic character of such LPS molecules. Previous studies have shown the significance of an amide of galacturonic acid with lysine [D-GalA(L-Lys)] for serological specificity of O-antigens from few P. mirabilis strains. In this work, the immunodominant role of GalALys was indicated for the P. penneri 42 LPS core region. The studies also showed the serological identity of core oligosaccharides from P. penneri 42 (O71), P. mirabilis 51/57 (O28) and R14/S1959 strains. from P. penneri 42 (O71), P. mirabilis 51/57 (O28) an…
Hepatocytes cultured in alginate microspheres: an optimized technique to study enzyme induction.
2004
An important application of hepatocyte cultures is identification of drugs acting as inducers of biotransformation enzymes that alter metabolic clearance of other therapeutic agents. In the present study we optimized an in vitro system with hepatocytes cultured in alginate microspheres that allow studies of enzyme induction with excellent sensitivity. Induction factors obtained with standard inducers, such as 3-methylcholanthrene or phenobarbital, were higher compared to those with conventional hepatocyte co-cultures on collagen coated dishes. This is illustrated by activities of 7-ethoxyresorufin-O-deethylase (EROD) after incubation with 5 microM 3-methylcholanthrene (3-MC), a standard ind…
EFFECT OF MICROENCAPSULATION ON OXYGEN DISTRIBUTION IN ISLETS ORGANS
1994
In islet transplantation, limitation of oxygen supply may restrict graft function, particularly when encapsulated tissue is used. Therefore, oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami were measured. In a thermostatically (37 degrees C) controlled measuring chamber, PO2 values were recorded at subsequent microelectrode positions on a radial track toward the center of the organ. In 2 independent groups, we studied the effect of fluid convection (n = 12) and microencapsulation (n = 12). In both groups, sigmoidal PO2 profiles were found, which permit differentiation in an oxygen-depleted zone surrounding the surface, a steep decline inside the tissue…
Xenotransplantation of parathyroids in rats using barium-alginate and polyacrylic acid multilayer microcapsules
2001
The integrity and function of encapsulated parathyroid tissue following xenotransplantation is limited by oxygen and nutrition supply and capsule fibrosis. Since some of these factors depend on stability and biocompatibility of the coating material, multilayer microcapsules have been developed. Parathyroid tissue pieces and digested single cells from pigs were encapsulated in barium-alginate and in polyacrylic acid (PAA) multilayer capsules. After 7 days of culture the function of the encapsulated cells were assessed. Subsequently, in a part of the cultured microcapsules the viability was directly assessed whereas the other part was transplanted in dark animal [DA] rats for 30 days. After e…
Heparin–polynitroxides: Synthesis and preliminary evaluation as cardiovascular EPR/MR imaging probes and extracellular space-targeted antioxidants
2011
We report here the synthesis of heparin-polynitroxide derivatives (HPNs) in which nitroxide moieties are linked either to uronic acid or glycosamine residues of the heparin macromolecule. HPNs have low anticoagulant activity, possess superoxide scavenging properties, bind to the vascular endothelium/extra-cellular matrix and can be detected by EPR and MRI techniques. As the vascular wall-targeted redox-active paramagnetic compounds, HPNs may have both diagnostic (molecular MRI) and therapeutic (ecSOD mimics) applications.
A way to follow the viability of encapsulated Bifidobacterium bifidum subjected to a freeze-drying process in order to target the colon: Interest of …
2012
The aim of this work was to apply flow cytometry in order to assess and compare the viability of freeze-dried entrapped bacteria with an usual technique by quantification by plate count techniques. It also aimed at studying the effect of various cryoprotectants on the viability of an entrapped Bifidobacterium bifidum subjected to freeze-drying to check their ability to be delivered all along the gastro-intestinal tract. The alginate-pectinate beads were chosen as the encapsulation matrix added with different protectants. The beads were characterized by scanning electron microscopy and the viability was checked by both methods. The best combination to improve viability of entrapped bacteria …