Gal Epitope (gal + epitope)

Distribution by Scientific Domains


Selected Abstracts


Structural analysis of ,-Gal and new non-Gal carbohydrate epitopes from specific pathogen-free miniature pig kidney

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2008
Yun-Gon Kim
Abstract The major barrier in transplantation of pig organs into humans is the presence of surface carbohydrate antigens (e.g., the Gal,1-3Gal,1-4GlcNAc-R (,-Gal) epitope) expressed on pig endothelial cells. In this study, total N -glycans from membrane glycoproteins derived from specific pathogen-free miniature pig kidney are identified by MALDI-TOF, negative ion ESI MS/MS and normal-phase HPLC (NP-HPLC) combined with exoglycosidase digestion. Over 100 N -glycans, including sialylated and neutral types, were identified. As well as the known ,-Gal antigens, some of these glycans contained novel non-Gal carbohydrate antigens such as (Neu5Gc-Gal-GlcNAc) and Gal,1-3Lewisx (Gal-Gal-(Fuc)GlcNAc) which have not been reported before in N -glycans from pig organs. The ability of MALDI, ESI, and HPLC to measure the relative proportions of the glycans was evaluated. The HPLC resolution was insufficient for accurate work and some minor differences were noted in the ionization efficiencies of different glycan groups when measured by the two mass spectrometric techniques. However, the results indicated that the relative quantity of ,-Gal epitope was in the region of 50% of the complex glycans. High-mannose type glycans were also abundant (35,43%) but appeared to be ionized more efficiently than the complex glycans by ESI than by MALDI. [source]


Production of ,-Galactosyl Epitopes via Combined Use of Two Recombinant Whole Cells Harboring UDP-Galactose 4-Epimerase and ,-1,3-Galactosyltransferase

BIOTECHNOLOGY PROGRESS, Issue 4 2000
Xi Chen
,-Galactosyl epitopes (or ,-Gal, oligosaccharides with a terminal Gal,1,3Gal sequence) are a class of biologically important oligosaccharides in great demand in bulk quantities for basic and clinical studies on preventing hyperacute rejection in pig-to-primate organ xenotransplantaion. A truncated bovine ,-1,3-galactosyltransferase, the key enzyme responsible for the biosynthesis of the terminal structure of ,-Gal, was cloned and overexpressed previously. The acceptor specificity was further studied in the present paper, and lactose and galactose derivatives were found to be good acceptors. To develop a more proficient reaction process, we report herein an example of an efficient enzymatic synthesis of ,-Gal oligosaccharides catalyzed by the combination of two recombinant Escherichia coli whole cells harboring the genes of a UDP-galactose 4-epimerase and the ,-1,3-galactosyltransferase, respectively. Using lactosyl azide (LacN3) as the acceptor for the glycosyltransferase, the combined use of the two recombinant cells efficiently produced ,-Gal epitope Gal,1,3LacN3 in 60,68% yield. [source]


Immunoaffinity removal of xenoreactive antibodies using modified dialysis or microfiltration membranes

BIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003
Sujatha Karoor
Abstract Hyperacute rejection following xenogeneic transplantation in primates is mediated by naturally occurring IgM antibodies, which are specifically directed to ,-Galactosyl residues on many nonprimate mammalian cells. Current approaches to remove these anti-,Gal IgM include plasmapheresis followed by immunoaffinity adsorption on bead columns using synthetic Gal epitopes, which requires two pieces of complex equipment. In this study, we explored the use of immunoaffinity adsorption with hollow fiber microporous or dialysis membranes to which a synthetic ,Gal trisaccharide ligand is bound. Covalent attachment of ligand directly to the surface produced negligible binding, but use of long-chain polyamines as reactive spacers yielded binding densities for anti-,Gal IgM as high as 89 mg/mL membrane volume in breakthrough curve experiments with microporous nylon membranes having an internal surface area of 4.2 m2/mL membrane volume. A crossflow microfilter fabricated from the membranes described in this study and having about 0.4 m2 luminal surface area would be able to carry out plasma separation and immunoadsorption in a single device with a large excess of binding capacity to ensure that all plasma that filters across the device and is returned to a human patient is essentially free of anti-,Gal IgM. We conclude that immunoaffinity removal of xenoreactive antibodies using microfiltration hollow fiber membranes is feasible and has potential advantages of efficiency and simplicity for clinical application. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 134,148, 2003. [source]


The Effect of Lyophilization on Graft Acceptance in Experimental Xenotransplantation Using Porcine Cornea

ARTIFICIAL ORGANS, Issue 1 2010
Jeong-Kyu Lee
Abstract The immunogenicity of lyophilized porcine cornea is unknown. The purpose of this study was to examine the possibility of using lyophilized porcine cornea as a substrate for ocular surface reconstruction. A porcine cornea stromal button was freeze-dried and vacuum-packed. Lyophilized and fresh porcine corneas were examined histologically, and then implanted into intrastromal pockets in live rat corneas. Cytokine concentrations in plasma and protein extracts from the corneal buttons of rats were measured using the fluorokine multianalyte profiling assay, and histologic examination was performed. Immunoreactivity to the ,-gal epitope was not found in lyophilized porcine corneas, whereas it was found in several keratocytes in fresh porcine corneas. The median survival time of rat corneas receiving lyophilized porcine transplants was 28.0 days, significantly longer than the 14.0-day survival of rat corneas that received fresh porcine transplants (P < 0.05). CD45RO+ and CD68+ cells were observed in rejected corneas, and interleukin-2 and interferon-, were elevated in rat plasma and corneal tissue. The lyophilized porcine corneal stroma, which is devoid of ,-gal epitope, is less antigenic, and may be a useful biomaterial for ocular surface reconstruction and corneal collagen supplementation. [source]