Biomedical subjects

J D Springfield

Publications and source records attributed to J D Springfield.

5 recordsLinked to original sources

PubMed1988

Seroepidemiology of group B Streptococcus type II antibody specificity.

The specificity of human antibodies for the two major sidechain determinants of the type II group B streptococcal (GBS) polysaccharide was examined in 90 pairs of maternal and cord sera. Using an ELISA system, total antibody was measured against the complete (sialylated) type II antigen and the proportion of antibody against the galactose determinant was estimated by inhibition with free beta-methylgalactopyranoside. Mothers colonized by type II or by other GBS types had higher levels of total specific antibody (means, 3.3 and 4.7 micrograms/ml, respectively) than those not colonized (mean, 2.2 micrograms/ml). Cord sera averaged 1-2 micrograms/ml lower than maternal sera. Colonization with GBS was also associated with higher levels against the galactose determinant (mean, 1.5 micrograms/ml, compared to 0.7 micrograms/ml for those not colonized). The distribution of specificities favoured antibodies against the sialic acid determinant in maternal but not cord sera. Specificity as well as antibody level may play a role in the epidemiology of GBS type II.

Antibodies, Bacterial↗

PubMed1987

Type-specific streptococcal antibodies in amniotic fluid.

Type-specific antibodies against group B streptococcal and pneumococcal capsular antigens were measured in 68 amniotic fluid samples from healthy women between 16 and 20 weeks of pregnancy. Mean antibody levels ranged from 0.13 to 0.61 microgram/ml, with few samples having greater than 1 microgram/ml against any antigen. The role of antibodies in protection against intrauterine infection is discussed.

Adult↗

PubMed1982

Effect of phospholipids on alpha-1,2-mannosidase activity.

An alpha-1,2-mannosidase has been solubilized and partially purified from rabbit liver microsomes (Forsee, W. T., and Schutzbach, J. S. (1981) J. Biol. Chem. 256, 6577-6582). The partially purified enzyme was activated by the addition of zwitterionic phospholipids but maximal activity was found to be relatively independent of acyl chain length or degree of unsaturation. Titration of the enzyme with increasing concentrations of water-soluble and long acyl chain phospholipids demonstrated that an ordered lipid structure of either micelles or bilayers was required for alpha-mannosidase activity. Mixed micelles of Triton X-100 and zwitterionic phospholipids also activated the enzyme. The concentration of phospholipid in the mixed micelles required for activation was dependent upon acyl chain length, but maximal activity was unaffected by this parameter. The addition of negatively charged phospholipids not only failed to activate the enzyme but also inhibited alpha-mannosidase activity in the presence of zwitterionic phospholipids. Inhibition by negatively charged phospholipids was pH dependent with maximal inhibition at pH values of 6.0 or lower. These results suggest that the activity of the alpha-1,2-mannosidase could be subject to modulation by the composition and structure of the microsomal membranes.

Animals↗

PubMed1980

The biosynthesis of oligosaccharide-lipids. Isolation of an oligosaccharide-P-P-lipid acceptor.

An oligosaccharide-P-P-lipid has been isolated from porcine liver by extraction with organic solvents and purified by chromatography on silica gel and DEAE-cellulose. The purified oligosaccharide-lipid was shown to contain mannose and N-acetylglucosamine in an approximate ratio of 1:1 and our results suggest that the major oligosaccharide component in the preparation was a tetrasaccharide with the composition (Man)2 (GlcNAc)2. When the oligosaccharide-lipid was incubated with GDP-[14C]mannose and a solubilized enzyme preparation from rabbit liver in the presence of MgCl2, three radioactive products could be isolated. The oligosaccharides in the products could be identified as a penta-, a hexa-, and a heptasaccharide. These products were formed by the stepwise addition of mannose to the growing oligosaccharide chain and GDP-mannose was indicated as the glycosyl donor in each reaction.

Animals↗

PubMed1980

The biosynthesis of oligosaccharide-lipids. Formation of an alpha-1,2-mannosyl-mannose linkage.

An enzyme present in rabbit liver microsomes has been found to catalyze mannosyltransfer from GDP-mannose to exogenously added oligosaccharide-lipid acceptor resulting in the formation of an alpha-1,2-mannosyl-mannose linkage. Several lines of evidence suggest that the product is a heptasaccharide containing a single 1,6-linked branched glycosyl unit with 65% of the newly added mannosyl units in a terminal nonreducing position. The enzyme has been solubilized with non-ionic detergents and was partially purified on DEAE-cellulose and hydroxylapatite. The partially purified enzyme no longer catalyzed the formation of dolichol-P-mannose indicating a direct transfer from GDP-mannose to oligosaccharide-lipid acceptor.

Animals↗