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Biomedical subjects

R Oriol

Publications and source records attributed to R Oriol.

At least 55 records · Page 3Linked to original sources
PubMed1996

The reducing end of alpha Gal oligosaccharides contributes to their efficiency in blocking natural antibodies of human and baboon sera.

Synthetic galactosyl oligosaccharides were tested for their ability to inhibit the cytotoxic reaction of human and baboon natural antibodies on PK15 cells in culture. Methyl-alpha-Gal gave weak inhibition, Gal alpha 1-3Gal substantially inhibited the reaction (400muM), and Gal alpha 1-3Gal beta 1-4GLcNAc was ten times more efficient (30 muM). The modification from alpha to beta anomeric configuration of the nonreducing end resulted in a complete loss of activity, while substitutions at the reducing end induced only a partial loss of activity. These observations suggest that natural anti-alphaGal antibodies recognize the epitope from its nonreducing end, but that substitutions at the reducing terminus can modify the antibody-binding capacity. Modified tri- and tetrasaccharides are better inhibitors than the disaccharide but not as good as Gal alpha 1-3Gal beta 1-4GlcNAc. The reducing terminus therefore contributes some energy to the reaction, indicating that certain oligosaccharides will be of more potential clinical use than others.

Animals↗
PubMed1996

Recognition of the blood group H type 2 trisaccharide epitope by 28 monoclonal antibodies and three lectins.

The patterns of cross-reaction of 30 monoclonal antibodies and three lectins were determined by ELISA with 21 ABH, Ii or Lewis related synthetic oligosaccharides coupled to bovine serum albumin. At least seven main groups of cross-reactive patterns were identified among the antibodies, plus several isolated antibodies which had intermediate patterns between two of the main antibody groups. The three lectins had different cross-reaction patterns, Galactia tenuiflora was different from all the antibodies, Ulex europaeus lectin 1 and Lotus tetragonolobus were similar, but not identical to groups III and V of antibodies respectively. The anti-H antibodies cross-reacting with A type 2 gave similar agglutination scores with all the normal ABO erythrocytes, while the anti-H antibodies not cross-reacting with A type 2 reacted with different scores: O > A2 > A2B > B > A1 > A1B > O(h), suggesting that these antibodies react better with the free H epitopes and do not recognize the H in A or B epitopes. Based on the ELISA and agglutination results and the lowest energy conformations of each oligosaccharide obtained by computer modelling, the most probable oligosaccharide surface areas recognized by each antibody main group are illustrated.

ABO Blood-Group System↗
PubMed1996

Molecular basis for erythrocyte Le(a+ b+) and salivary ABH partial-secretor phenotypes: expression of a FUT2 secretor allele with an A-->T mutation at nucleotide 385 correlates with reduced alpha(1,2) fucosyltransferase activity.

The SewA385T mutation of the FUT2 gene was found to correlate with both the erthrocyte Le(a + b+) and/or salivary ABH partial-secretor phenotypes of Polynesians. Constructs with FUT1 and FUT2 wild type genes, and the FUT2 SewA385T, seG428A and seC571T mutated alleles, were cloned into pcDNAI, and expressed in COS-7 cells. COS-7 cells transfected with the SewA385T allele had weak, but detectable, alpha(1,2)fucosyltransferase activity, with an acceptor substrate pattern similar to the wild type FUT2 gene. Comparative kinetic studies from cell extracts with mutated SewA385T and wild type FUT2 alleles gave similar Km values, but less enzyme activity was present in cells transfected with SewA385T (Vmax 230 pmol h-1 mg-1), as compared to those transfected with FUT2 (Vmax 1030 pmol h-1 mg-1), suggesting that the mutated enzyme is more unstable. These results confirm that the molecular basis for the erythrocyte Le(a + b+), and the associated ABH salivary partial-secretor phenotype, is an amino acid change of Ile129-->Phe in the secretor alpha(1,2)fucosyltransferase.

ABO Blood-Group System↗
PubMed1996

How do antibodies and lectins recognize histo-blood group antigens? A 3D-QSAR study by comparative molecular field analysis (CoMFA).

The cross-reaction patterns of nine antibodies and three lectins against 12 H type 2 related oligosaccharides have been analysed by means of 3D-QSAR study. Three-dimensional descriptors of the molecular properties have been used in comparative molecular field analysis (CoMFA). Three different alignments were considered for the oligosaccharides. One, based on the superimposition of the oligosaccharide core, could be correlated to most of the antibody activities. A second alignment, based on a superimposition of the fucose residue, had to be taken into account for explaining the binding properties of Ulex europaeus isolectin I. Analysis of the QSAR data gives indications on the carbohydrate epitopes essential for antibody recognition and yields some insights about the nature of the molecular recognition. This study complements previous biochemical estimates of the H type 2 related oligosaccharide binding areas (Mollicone, R.; Cailleau, A.; Imberty, A.; Gane, P.; Pérez, S.; Oriol, R. Glycoconj. J. 1996, 13, 263-271).

Antibodies↗
PubMed1996

Identification of a new plasma alpha(1,3)fucosyltransferase (FUT6) allele requires an extended genotyping strategy.

Screening the FUT6 gene of 40 Swedish individuals, originally selected for genotyping of FUT3, revealed an unexpected high frequency of mutations. Four were originally typed as homozygous for the enzyme lethal mutation G739A by Taq alpha I restriction pattern, but only one lacked plasma alpha(1,3)fucosyltransferase activity. Cloning and sequencing of FUT6 from 2 of them revealed a new allele, without the G739A mutation, but with two new point mutations C738T and G977A. Segregation of this allele was confirmed in Swedish and Indonesian families. Since G739A and C738T mutations are only one nucleotide apart and induce the same modification of Taq alpha I cleavage, a new screening strategy for FUT6 was adopted. The homozygous inactivating G739A mutation was for the first time identified in Caucasian and Polynesian individuals, both lacking plasma enzyme activity. The mutation C370T was present in 25 of the 40 Swedish individuals and the inactivating mutation C945A was not found at all. These findings stress the dangers of transferring restriction enzyme genotype strategies from one population to another and of inferring phenotypes from genotypes without phenotyping and/or performing confirmatory cloning and sequencing.

Alleles↗
PubMed1996

Associations of blood group-related antigens to FEV1, wheezing, and asthma.

Discordant results have been observed regarding the associations of chronic obstructive pulmonary diseases with secretor, Lewis, and ABO histo-blood groups, which are defined by glycosyltransferases. These enzymes build up oligosaccharide structures that play a role in the adhesion of environmental factors to epithelial cells. The objectives of the present study were to assess the role of all three systems, Lewis (Le), salivary ABH secretor (Se), and red cell blood group ABO, on lung function, wheezing, and asthma in a cohort of 228 coal miners studied cross-sectionally, considering the potential modifying effect of environmental factors on these associations. Asthma was significantly related to nonsecretor phenotype. Significantly lower lung function and higher prevalences of wheezing and asthma were observed in Lewis-negative or nonsecretor subjects of blood group O. Very low lung function values were observed in the small group of Lewis-negative nonsecretors who lack both Le and Se controlled fucoses (1% of Caucasians). Lewis-positive, salivary ABH secretors who have these two fucoses represent 70% of Caucasians. Among these subjects, lower lung function was observed in blood group A, and in a lesser extent in blood group B, i.e., with terminal alpha GaINAc or alpha Gal respectively, than in blood group O subjects. ABO, Lewis, and secretor phenotypes did not account for the potential genetic heterogeneity of subjects toward smoking, but alcohol consumption appeared to exert a protective effect on lung function in Lewis-negative subjects (10% of Caucasians). If confirmed in other populations, the magnitude of the effects observed regarding low lung function in Lewis-negative ABH nonsecretors, and the protective effect of Lewis negative on the deleterious effect of alcohol, may be of clinical importance. Further studies of the combined effects of various histo-blood group genetic systems seem worthwhile, particularly for airflow limitation, wheezing, and asthma, possibly with reference to susceptibility to infectious agents.

ABO Blood-Group System↗
PubMed1996

Fucosyltransferase genes are dispersed in the genome: FUT7 is located on 9q34.3 distal to D9S1830.

Synthesis of A, B, H, Lewis and related histo-blood group antigens is catalyzed by different fucosyltransferases. Enzymatic acceptor specificity and tissue expression permit the definition of 2 types of alpha-2-fucosyltransferases and 5 types of alpha-3-fucosyltransferases encoded by specific genes registered as FUT1 to FUT7. We have previously assigned FUT4 to 11q21, the cluster FUT1-FUT2 to 19q13.3 and the cluster FUT6-FUT3-FUT5 to 19p13.3. The last gene cloned (FUT7) encodes an alpha-3-fucosyltransferase expressed in leukocytes which synthesizes the sialyl Lĕ antigen, a selectin ligand. We have localized this gene by PCR assay using somatic cell hybrids, which retain rearrangements of chromosome 9 characterized in respect with the genetic microsatellite map, and then by screening a cosmid library. We assign FUT7 to chromosome band 9q34.3 telomeric to D9S1830 and close to the genes ABC2 and C8G.

Chromosome Mapping↗
PubMed1995

Genetic control of the humoral immune response to xenografts. I. Functional characterization of rat monoclonal antibodies to hamster heart xenografts.

The rejection of cardiac xenografts in the hamster-to-rat combination is characterized by the production of IgM antibodies that result in the rapid loss of the graft. We have recently produced rat monoclonal antibodies (mAb) to hamster heart xenografts in an attempt to develop reagents for use in identifying the target antigens for this reaction and to study the nature of the genetic control of the humoral response. The monoclonals were created by the fusion of myeloma cells with splenic lymphocytes from LEW rat recipients of hamster cardiac xenografts. The hybridomas were screened for antibody production, reactivity to hamster cell surface antigens, and the ability to mediate hyperacute rejection of hamster heart xenografts. A panel of monoclonal antibodies has been identified that are capable of inducing hyperacute rejection. All of these mAbs are IgM and bind strongly to hamster vascular endothelium. None of the mAbs were lymphocytotoxic or bound to hamster lymphocytes or erythrocytes. Immunopathologic studies demonstrated that these mAbs react specifically with hamster vascular endothelium and mediate a complement-dependent humoral reaction leading to the destruction of the cardiac xenografts. One of the mAbs (designated as HAR-1) has been characterized in detail. HAR-1 detects antigens distributed in the vascular endothelium, epithelium of bronchi in the lung, small intestine, tubules of kidney, and selective components of lymphoid organs--e.g., the stromal cells of the spleen and thymic medullary epithelium. Western blot analysis of hamster heart proteins with HAR-1 showed multiple bands with two major bands migrating at 80 kDa and 48 kDa. Absorption of the HAR-1 antibody with 48 individual carbohydrate molecules demonstrated that the strongest reactivity of the antibody is with a sialyl-Lea carbohydrate antigen.

Animals↗
PubMed1995

Computer simulation of histo-blood group oligosaccharides: energy maps of all constituting disaccharides and potential energy surfaces of 14 ABH and Lewis carbohydrate antigens.

The three-dimensional structures of fourteen histo-blood groups carbohydrate antigens have been established through a combination of molecular mechanics and conformational searching methods. The conformational space available for each disaccharide, constituents of these determinants, has been throroughly characterized. The results have been organized in a data bank fashion. Larger relatives, i.e. 14 tri- and tetrasaccharides of histo-blood group antigens, have been modelled using a different method for exploring the complex potential energy surface. This approach is aimed at establishing all the possible families of conformations, along with the conformational pathways. Different conformational behaviours are exhibited by these oligosaccharides. Some of them, i.e. Le(x) and Le(y) tri and tetrasaccharides, are very rigid; 99% of their populations belong to the same conformational family. Others, like H type 1, H type 2 or H type 6 oligosaccharides, are essentially rigid, but a secondary conformational family, corresponding to 3-4% of the total population, can arise. Finally, the H types 3 and 4 trisaccharides, and the A type 1 and A type 2 tetrasaccharides are predicted to behave rather flexibly. The information gathered in the present investigation has been used to analyse the body of experimental evidence, either physical or biological, available for this series of carbohydrate antigens. Of special interest are the several different alignments that can be proposed for these molecules. They yield a realistic definition of the three-dimensional features of the epitopes thereby providing essential information about how carbohydrate antigens are recognized by proteins.

ABO Blood-Group System↗
PubMed1995

Molecular genetics of H, Se, Lewis and other fucosyltransferase genes.

Seven human fucosyltransferase genes have been cloned and registered in the Genome Data Base (GDB) as FUT1 to FUT7. According to their acceptor specificity, two main groups of enzymes can be distinguished. The alpha-2-fucosyltransferases: FUT1 (H) of red cells and vascular endothelium and FUT2 (Se) of exocrine secretions. The alpha-3-fucosyltransferases: FUT3 (Lewis) of exocrine secretions; FUT4 (myeloid) of white cells and brain; FUT5 whose tissue distribution has not been defined as yet; FUT6 (plasma) present in plasma, renal proximal tubules and hepatocytes; FUT7 (leukocyte) found in neutrophils. A high DNA sequence homology has been detected among the genes within each of these two groups, while no homology has been detected between the genes of the two groups. Point mutations responsible of inactivating genetic polymorphisms have been found for FUT1, FUT2, FUT3 and FUT6, while FUT4 and FUT7 seem to be genetically monomorphic. FUT4 has been detected in all tissues of 5 to 10 weeks old human embryos suggesting that it may play a role in development. FUT7 is a candidate for the control of the synthesis of the receptors of selectin mediated cell adhesion.

Blood Group Antigens↗
PubMed1995

A new monoclonal antibody (3D3) generated with human respiratory mucins and directed against Lewis determinants.

We have prepared a monoclonal antibody (MAb), 3D3, raised against purified human respiratory mucins. This antibody recognized mucins and proteolytically derived glycopeptides. The epitope recognized by the antibody was destroyed by alpha-L-fucosidase, indicating that it was present on the carbohydrate moieties. Structural specificity was determined by adsorption on a variety of synthetic, insolubilized oligosaccharides. Several lines of evidence indicate that the 3D3 MAb reacted strongly with the Lewis (Leb) antigen, but also recognized Le(a) and Le(y) determinants. This antibody might be useful to study mucin secretion.

Adsorption↗
PubMed1995

Lewis histo-blood group system and associated secretory phenotypes.

This review summarises present knowledge of the chemistry, immunology, genetics and clinical significance of antibodies in the Lewis and secretor histo-blood group systems. Although red cell serology has laid the foundations for these systems, more recent advances have been made by studying Lewis and related glycoconjugates with monoclonal antibodies, determining structures by mass spectrometry and NMR spectroscopy, identifying enzymes and their specificities, and identifying the genes by molecular biology. The expression of Lewis system antigens is dependent on Lewis and secretor loci. Fucosyltransferases coded by genes at these loci compete and interact with each other and with other transferases to determine an individual's Lewis and secretor phenotype. Exocrine epithelial cells, mostly of endodermal origin, synthesise the Lewis antigens which, as plasma glycolipids, are secondarily acquired by cells of the peripheral circulation. Phenotyping red cells is often regarded as a simple way of determining the Lewis and sometimes the secretor status of an individual; however, the red cell phenotype is influenced by many factors and may not necessarily reflect someone's Lewis and secretor genotypes. Two main red cell Lewis groups are usually found, Lewis negative and Lewis positive. In Lewis-negative individuals, the secretor genotype does not affect the Lewis phenotype, but in Lewis-positive individuals, the non-secretor genotype generates the Le(a+b-) phenotype, the secretor genotype causes the Le(a-b+) phenotype, and the partial secretor genotype gives rise to the Le(a+b+) phenotype.

Carbohydrate Sequence↗
PubMed1995

Relative positions of two clusters of human alpha-L-fucosyltransferases in 19q (FUT1-FUT2) and 19p (FUT6-FUT3-FUT5) within the microsatellite genetic map of chromosome 19.

Five on the seven cloned human fucosyltransferase genes have been mapped to two clusters, one on 19q and the other on 19p. Comparative DNA sequence analysis showed the Généthon microsatellite D19S596 lies 2.2 kb downstream of the coding region of FUT1, indicating that the cluster comprising the closely linked FUT1 and FUT2 genes is located 4 cM distal to D19S412 (lod score 13.7) and 9 cM proximal to D19S571 (lod score 11.7). Polymorphic markers of FUT3, FUT5, and FUT6 were used for linkage analysis with 14 Généthon microsatellites in Indonesian families. These three loci constitute a cluster on 19p, located between the Généthon microsatellites D19S216 and D19S567, which are known to be only 1 cM distant from each other. Two cross-overs, one between FUT6 and FUT3 and the other between FUT3 and FUT5, suggest the gene order 19pter-D19S216-FUT6-FUT3-FUT5-D19S567++ +-cen. Comparison of genetic and physical maps suggests that the FUT6-FUT3-FUT5 cluster is located on 19p13.3 and the FUT1-FUT2 cluster on 19q13.3. FUT6, FUT3 and FUT5 genes share more than 85% homology and encode three similar, but distinct alpha(1,3) fucosyltransferases. FUT1 and FUT2 share about 70% homology and encode two distinct alpha(1,2)fucosyltransferases. No sequence homology was found between the genes of the two clusters. The members of each of these two clusters have probably emerged by duplication and divergent evolution of two unrelated ancestor genes.

Base Sequence↗