Biosynthesis of blood group ABH antigens: genetic regulation and tissue distribution.
Explore the source record for details and available documents.
ABO Blood-Group System↗
Biomedical subjects
W M Watkins
Publications and source records attributed to W M Watkins.
Differential subcompartmentation of terminal glycosylation in the Golgi apparatus of intestinal absorptive and goblet cells.
Two terminal glycosyltransferases, a sialyltransferase and the blood group A alpha 1,3 N-acetylgalactosaminyltransferase, were found to exhibit differential subcompartmentation in the Golgi apparatus of intestinal goblet and absorptive cells. As expected from their role in terminal glycosylation, the two glycosyltransferases and their products, sialic acid residues and blood group A substance, were localized in the trans cisternae of the Golgi apparatus of goblet cells. In contrast, however, they were found throughout the Golgi apparatus stack of adjacent absorptive cells, with the exception of the fenestrated first cis cisterna. The results are in contrast to the general view that enzymes in the glycosylation pathway are arranged in a cis to trans gradient across the Golgi apparatus and that such polarized distributions may instead be cell type-specific.
ABO Blood-Group System↗
Glycosyltransferases. Early history, development and future prospects.
Explore the source record for details and available documents.
Animals↗
UDP-N-acetyl-D-galactosamine as a donor substrate for the glycosyltransferase encoded by the B gene at the human blood group ABO locus.
The properties of the enzyme in the serum of blood group B individuals that catalyses the transfer of small amounts of N-acetyl-D-galactosamine to H-active precursor structures were compared with those of the blood group B gene-associated alpha-(1----3)-D-galactosyltransferase and with the blood group A gene-associated alpha-(1----3)-N-acetyl-D-galactosaminyltransferases in the serum of blood group A1 and A2 individuals. The biosynthetic products formed by the enzyme in B serum were identical with the A-active structures synthesised by the A1 and A2 gene-associated alpha-(1----3)-N-acetyl-D-galactosaminyltransferases but the enzyme differed from the A1 and A2 transferases in its apparent Km for UDP-N-acetyl-D-galactosamine, its heat susceptibility, its failure to bind to Sepharose 4B, and its adsorption to H-active sites on group O red cell ghosts under conditions which bind the B transferase but fail to adsorb the A1 and A2 transferases. The correlation between the levels of alpha-(1----3)-D-galactosyltransferase and alpha-(1----3)-N-acetyl-D-galactosaminyltransferase activities in all the group B serum samples tested, the maintenance of the same ratio of activities after successive cycles of binding to group O red cell ghosts, the retention of the ability to convert blood group O to A-active cells after treatment of the serum with Sepharose 4B, and the failure to detect any comparable activity in group O serum samples tested under the same conditions indicated that the enzyme in group B serum that utilises UDP-N-acetyl-D-galactosamine to make blood group A-active structures is the B gene-associated alpha-(1----3)-D-galactosyltransferase.
ABO Blood-Group System↗
Association of the human Lewis blood group Le(a-b-c-d-) with the failure of expression of alpha-3-L fucosyltransferase.
Two unrelated individuals are reported who lack alpha-3-L-fucosyltransferase activity in their serum and saliva. Both were blacks, one from the United States and the other from South Africa. No other of the tested members of their families lacked this enzyme. A survey of more than 2000 serum samples from both black and white South African blood donors, black United States donors and white United Kingdom donors failed to disclose another example of a serum deficient in alpha-3-L-fucosyltransferase activity. The two individuals lacking in alpha-3-L-fucosyltransferase activity both had the Lewis blood group phenotype Le(a-b-c-d-). No other persons with this phenotype have been reported. The absence of Lec activity in the two individuals who are deficient in alpha-3-L-fucosyltransferase is consistent with the interpretation that alpha-3-linked L-fucose is an essential part of the antigenic determinant recognised by the anti-Lec reagent used in this investigation.
Black People↗
In vitro response of Kenyan Plasmodium falciparum to chloroquine in different media.
Explore the source record for details and available documents.
Animals↗
Antagonism of sulfadoxine and pyrimethamine antimalarial activity in vitro by p-aminobenzoic acid, p-aminobenzoylglutamic acid and folic acid.
The activity of pyrimethamine and sulfadoxine against two strains of Plasmodium falciparum has been studied in vitro by a radioisotopic technique. Low level antagonism of pyrimethamine resulted from the inclusion of p-aminobenzoic acid, p-aminobenzoylglutamic acid or folic acid in the test medium. Sulfadoxine activity was antagonised slightly by p-aminobenzoic but not by p-aminobenzoylglutamic acid, and antagonised markedly by folic acid at concentrations above 4 X 10(-8) M. At 10(-7) M folic acid, a concentration lower than that of normal RPMI medium 1640, sulfadoxine activity was reduced 7000 to 9000-fold in comparison with controls. These results are of importance in terms of the utilisation of folates by P. falciparum, the susceptibility of the parasite to antifolate drugs and the in vitro determination of parasite susceptibility.
4-Aminobenzoic Acid↗
Characterisation of a blood-group A-active tetrasaccharide synthesised by a blood-group B gene-specified glycosyltransferase.
The B gene-specified alpha-D-(1----3)-galactosyltransferase, isolated from the serum of a blood-group B individual, was used to catalyse the transfer of N-acetyl-D-galactosamine from UDP-N-acetyl-D-galactosamine to the blood-group H-active trisaccharide 2'-fucosyllactose. The biosynthetic product had blood-group A activity and its structure was confirmed as alpha-D-GalpNAc-(1----3)-[alpha-L-Fucp-(1----2)]-beta-D-Galp-(1--- -4)-D-Glc by methylation analysis and high-resolution 1H-n.m.r. spectroscopy. This tetrasaccharide was structurally and serologically identical with that made from the same donor and acceptor substrates when the blood-group A gene-specified alpha-D-(1----3)-N-acetylgalactosaminyltransferase was used as the enzyme source. The enzyme encoded by the B gene at the blood group ABO locus thus has overlapping donor substrate specificity with the enzyme encoded by the allelic A gene, and this property confers upon the B gene-specified alpha-D-1----3)-galactosyltransferase the potential to synthesise blood-group A-active structures.
ABO Blood-Group System↗
Effectiveness of amodiaquine as treatment for chloroquine-resistant Plasmodium falciparum infections in Kenya.
Studies were conducted in Malindi, Kenya, to assess the response of Plasmodium falciparum to chloroquine and amodiaquine in vivo (by an extended 14-day test) and in vitro (with the Rieckmann micro test). In-vivo resistance was demonstrated in 19 of 69 (28%) infections treated with chloroquine, but in only 2 of 60 (3.3%) of those treated with amodiaquine (p less than 0.001). In-vitro resistance to chloroquine was demonstrated in 15 of 23 (65%) tests. In contrast, 22 of the same 23 isolates were sensitive to amodiaquine in vitro. Effective concentrations by probit analysis for 50% and 99% (EC50 and EC99) inhibition, respectively, were 180.7 and 4319.6 nmol/l for chloroquine and 12.2 and 147.0 nmol/l for amodiaquine. The results suggest that amodiaquine is effective for the treatment of chloroquine-resistant falciparum malaria in Kenya.
Adolescent↗
The activity of proguanil and its metabolites, cycloguanil and p-chlorophenylbiguanide, against Plasmodium falciparum in vitro.
Using an in vitro radioisotopic method, the activity was measured of proguanil, its metabolites cycloguanil and p-chlorophenylbiguanide (PBG), pyrimethamine, and chloroquine against seven Kenyan and three South East Asian strains of Plasmodium falciparum. Five Kenyan isolates were sensitive to both pyrimethamine and cycloguanil in vitro, while the Smith and two Kenyan strains were resistant to both these drugs. Cross-resistance was incomplete: the Camp strain was resistant to pyrimethamine but not cycloguanil, and the FVO strain was resistant to cycloguanil but not pyrimethamine. Both proguanil and PBG exhibited weak antimalarial activity in vitro, but inhibitory blood levels of either compound are unlikely to occur after a normal human dose of proguanil. The results indicate that the activity of proguanil against P. falciparum is due entirely to the action of its active metabolite cycloguanil.
Animals↗
Synergistic antimalarial activity of pyrimethamine and sulfadoxine against Plasmodium falciparum in vitro.
Two strains of Plasmodium falciparum were tested in vitro for sensitivity to the dihydrofolate reductase inhibitor pyrimethamine, the p-aminobenzoic acid (PABA) analogue sulfadoxine, and combinations of both drugs. One strain was sensitive and one resistant to pyrimethamine in vitro. Parasites cultured in medium containing neither folic acid nor PABA were inhibited by 10(-6) M sulfadoxine, a concentration well below that achievable after therapeutic dosage. Folic acid added to this medium at a physiological concentration of 0.01 mg/liter caused a 1,000-fold reduction in sulfadoxine activity; a 100-fold higher concentration of folic acid caused a 10-fold reduction in pyrimethamine activity. Sulfadoxine in a concentration of 10(-7) M was able to potentiate pyrimethamine activity in PABA-free medium with no added folic acid or with 0.01 mg folic acid/liter. These data indicate that P. falciparum can utilize exogenous folic acid, and suggest that sulfadoxine may potentiate pyrimethamine activity by simultaneous inhibition of dihydrofolate reductase.
4-Aminobenzoic Acid↗
In vitro antimalarial activity of tetrahydrofolate dehydrogenase inhibitors.
Three tetrahydrofolate dehydrogenase (dihydrofolate reductase = EC 1.5.1.3) inhibitors were tested for antimalarial activity against Plasmodium falciparum, using an in vitro radioisotopic technique. Activity of each drug was tested in both normal RPMI medium 1640 and in modified medium (containing no p-aminobenzoic acid and 2.27 X 10(-8) M folic acid) after a 24- or 48-hour exposure. Activity was increased 20- to 85-fold using the modified medium and the longer exposure time. Under all conditions, pyrimethamine and cycloguanil were of equal or greater potency than an experimental pyrimethamine analogue, M&B 35769, against pyrimethamine-sensitive strains, but M&B 35769 was more active than either pyrimethamine or cycloguanil against pyrimethamine-resistant strains.
Animals↗
A new in vitro test for pyrimethamine/sulfadoxine susceptibility of Plasmodium falciparum and its correlation with in vivo resistance in Kenya.
A useful in vitro method for field evaluation of Plasmodium falciparum sensitivity to pyrimethamine/sulfadoxine is described. Thirty-five Kenyan schoolchildren infected with P. falciparum were treated with this drug combination and followed up for 5 weeks. In vitro tests for sensitivity to these drugs and to chloroquine were performed before starting treatment. All infections cleared within 7 days of treatment, but 5 children had recurrent parasitaemia within 35 days. The original isolates from 4 of these 5 children had an in vitro response to pyrimethamine/sulfadoxine similar to a known strain that was resistant to these drugs; only 4 of the remaining 30 isolates from patients in whom recurrent parasitaemia did not occur had a resistant in vitro response (P = 0.006). In the patient with recurrent parasitaemia whose initial isolate appeared sensitive to pyrimethamine/sulfadoxine, the recurrent isolate had a resistant pattern in vitro, suggesting either reinfection or selection of a resistant subpopulation following treatment. The in vitro response to this drug combination was correlated with the in vitro response to either drug alone and with the in vitro response to chloroquine. Two of the 5 infections with recurrent parasitaemia after initial pyrimethamine/sulfadoxine treatment were resistant to chloroquine in vivo. The in vitro test for pyrimethamine/sulfadoxine should be useful for mapping the spread of multidrug-resistant P. falciparum.
Adolescent↗
Chloroquine resistant Plasmodium falciparum malaria in a local Kenyan: a case report.
Explore the source record for details and available documents.
Adult↗
Fucosyltransferase activities in human lymphocytes and granulocytes. Blood group H-gene-specified alpha-2-L-fucosyltransferase is a discriminatory marker of peripheral blood lymphocytes.
Human lymphocytes and granulocytes were examined for blood group H-gene-specified alpha-2-L-fucosyl-transferase, alpha-3-L-fucosyltransferase and blood group Le-gene-specified alpha-4-L-fucosyltransferase. No alpha-4-L-fucosyltransferase was detectable in either cell type. alpha-3-L-Fucosyltransferase was readily demonstrable in both lymphocytes and granulocytes and the levels of activity per 10(6) cells were approximately the same. In contrast, alpha-2-L-fucosyltransferase was detectable in lymphocytes but not in similar numbers of granulocytes. The absence of alpha-2-L-fucosyltransferase was confirmed in granulocytes isolated from the blood of eighty unselected donors and was independent of ABO blood group or ABH secretor status.
ABO Blood-Group System↗
A blood group Sda-active pentasaccharide isolated from Tamm-Horsfall urinary glycoprotein.
Human Tamm-Horsfall urinary glycoprotein from an individual of the blood group Sd(a+) phenotype was tritium-labelled by treatment with galactose oxidase and sodium boro[3H]hydride and was then digested with endo-beta-galactosidase. A series of dialysable, labelled fragments was released from which a pentasaccharide was isolated that strongly inhibited the agglutination of Sd(a+) red cells by human anti-Sda serum and hence contained the Sda determinant structure. Reduction, methylation analysis and sequential exo-glycosidase digestion established the structure of the pentasaccharide as: GalNAc beta(1 leads to 4)[NeuAc(2 leads to 3)]Gal beta(1 leads to 4)GlcNAc beta(1 leads to 3)Gal
Blood Group Antigens↗
Enzymes involved in the biosynthesis of glycoconjugates. A UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to 4)-saccharide (1 leads to 3)-2-acetamido-2-deoxy-beta-D- glucopyranosyltransferase in human serum.
A 2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase (N-acetylglucosaminyltransferase) that catalyses the transfer of 2-acetamido-2-deoxy-D-glucose from UDP-2-acetamido-2-deoxy-D-glucose to terminal nonreducing beta-D-galactosyl residues in disaccharides, oligosaccharides, glycoproteins, and glycolipids has been detected in human serum. The preferred acceptors are those with beta-D-galactosyl residues linked (1 leads to 4) to the subterminal sugar residue. Activity is greatest when the second sugar residue is 2-acetamido-2-deoxy-D-glucose but beta-D-Galp-(1 leads to 4)-D-Glc and beta-D-Galp-(1 leads to 4)-D-Man are also good acceptors. Compounds with beta-D-galactosyl groups linked (1 leads to 3) to 2-acetamido-2-deoxy-D-glucose are relatively poor acceptors and beta-D-Galp-(1 leads to 6)-D-GlcNAc is inactive. Oligosaccharides substituted with an L-fucose unit on the beta-D-galactosyl unit or on the adjacent sugar residue failed to accept 2-acetamido-2-deoxy-D-glucose. Similarly, glycoproteins with L-fucose or sialic acid substituents are less effective acceptors before removal of these sugars to expose more beta-D-galactosyl end-groups. The transferred 2-acetamido-2-deoxy-beta-D-glucopyranosyl residue is cleaved from the enzymic reaction products by the N-acetyl-beta-D-glucosaminidase from Jack beans. Methylation analysis of the products of 2-acetamido-2-deoxy-D-glucosyl transfer to N-acetyllactosamine [beta-D-Galp-(1 leads to 4)-D-GlcNAc] and lactose [beta-D-Galp-(1 leads to 4)-D-Glc] revealed that the terminal, nonreducing D-galactosyl group in both these acceptors had been 3-O-substituted with 2-acetamido-2-deoxy-D-glucose. Hence, the enzyme in human serum catalyses, in the presence of Mn2+, the reaction UDP-GlcNAc + beta-D-Galp-(1 leads to 4)-R leads to beta-D-GlcpNAc(1 leads to 3)-beta-D-Galp-(1 leads to 4)-R + UDP and is a UDP-2-acetamido-2-deoxy-D-glucose: beta-D-galactopyranosyl-(1 leads to to 3)-2-acetamido-2-deoxy-beta-D-glucopyranosyltransferase.
Carbohydrate Conformation↗
Two alpha-3-D-galactosyltransferases in rabbit stomach mucosa with different acceptor substrate specificities.
Homogenates of rabbit stomach mucosa were examined for enzymes catalysing the transfer of D-galactose from UDP-D-galactose to various low-molecular-weight acceptors of known structure. Treatment of the products with alpha and beta-D-galactosidases revealed that D-galactose was transferred in both alpha and beta-anomeric linkages. The beta-D-galactosyltransferase used N-acetylglucosamine and compounds containing terminal nonreducing beta-N-acetylglucosaminyl residues as acceptor substrates. The compounds accepting D-galactose in alpha-anomeric linkage had unsubstituted terminal non-reducing beta-D-galactosyl units or a fucose substituent on the carbon-2 position of a subterminal beta-D-galactosyl unit. Methylation analysis of the products formed with N-acetyllactosamine [beta-D-Galp(1 leads to 4)D-GlcNAcp] and 2'fucosyllactose [alpha-L-Fucp(1 leads to 2)-beta-D-Galp(1 leads to 4)D-Glcp] revealed that D-galactose was transferred to the carbon-3 position of the beta-D-galactosyl residue in both of these acceptor substrates. Competition experiments with the two substrates indicated that the transfer of D-galactose was catalysed in each case by a different alpha-3-D-galactosyltransferase. Differences were also observed in the solubility properties of the enzymes: the alpha-3-D-galactosyltransferase using acceptor substrates with unsubstituted beta-D-galactosyl residues was more readily soluble both in the presence and absence of detergents than the transferase using beta-D-galactosyl residues substituted at carbon-2 with L-fucose. These findings demonstrate that rabbit stomach mucosa has two distinct alpha-3-D-galactosyltransferases: one, which is more tightly membrane-bound, resembles the human B-gene-specified transferase in its acceptor specificity, and the second, which is a more soluble enzyme, transfers D-galactose to the same positional linkage in unsubstituted beta-D-galactosyl residues.
Animals↗