PubMed Health⌕ Search

Biomedical subjects

F M Unger

Publications and source records attributed to F M Unger.

34 records · Page 2Linked to original sources
PubMed1985

Synthesis of alternate linear and branched repeating units of the Escherichia coli LP 1092 capsular polysaccharide containing 3-deoxy-alpha-D-manno-2-octulosonic acid (KDO) linked to secondary positions of D-ribose.

The oligosaccharides, methyl 3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, methyl 2-O-beta-D-ribofuranosyl-3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, and methyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----2)-O-beta-D- ribofuranosyl-(1----2)-beta-D-ribofuranoside were prepared in high purity and good over-all yields. The constitutions of the trisaccharide derivatives correspond to the repeating units of the proposed linear and branched structures of the capsular polysaccharide(s) from Escherichia coli LP 1092. The alpha-KDO-(2----3)-beta-D-Ribf and alpha-KDO-(2----2)-beta-D-Ribf units were synthesized by a modification of the Helferich procedure using methyl (4,5,7,8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl bromide)-onate and appropriate beta-D-ribofuranosyl derivatives. The constitutional and configurational assignments were based on the 250-MHz 1H-n.m.r.-spectra of protected derivatives of the oligosaccharides.

Carbohydrate Conformation↗
PubMed1985

Determination of 3-deoxy-D-manno-octulosonic acid (KDO), N-acetylneuraminic acid, and their derivatives by ion-exchange liquid chromatography.

A liquid chromatography (1.6 MPa) system for the analysis of 3-deoxy-D-manno-2-octulosonic acid (KDO), N-acetylneuraminic acid (Neu5Ac), methyl alpha- and beta-glycosides of Neu5Ac and KDO, alpha-heptosyl-(1----5)-KDO, various sialyllactoses, alpha-KDO-(2----4)-KDO, alpha-KDO-(2----4)-KDO methyl alpha-glycoside, beta-KDO-(2----4)-KDO methyl beta-glycoside, D-glucuronic acid, D-glucurono-3,6-lactone, and D-galacturonic acid has been developed. Separation was achieved within 10 and 30 min by the use of a small column filled with a strongly basic, anion-exchange resin, Aminex A-29, and 0.75 or 10mM sodium sulfate solutions as mobile phases. This method allowed the determination of KDO and sialic acids in amounts of 100 ng (0.5 nmol) and 200 pg (0.6 pmol), respectively.

Chromatography, High Pressure Liquid↗
PubMed1985

Empirical 13C-n.m.r.-correlations between the Escherichia coli K 13 and LP 1092 capsular polysaccharides and model oligosaccharides containing D-ribose and 3-deoxy-D-manno-2-octulosonic acid.

The proton-decoupled, Fourier-transform, 13C-n.m.r. spectra of the two anomeric sodium (methyl 3-deoxy-7-O-beta-D-ribofuranosyl-alpha- and beta-D-manno-2-octulopyranosid)onates, of the two anomeric sodium [methyl 3-deoxy-7-O-(2-O-beta-D-ribofuranosyl-beta-D-ribofuranosyl)-alpha- or -beta-D-manno-2-octulopyranosid]onates, and of methyl 2-O-beta-D-ribofuranosyl-beta-D-ribofuranoside have been recorded. The constitutions of these compounds correspond to repeating units and partial structures of the capsular polysaccharides from Escherichia coli K 13, K 20, K 23, and LP 1092 strains. The 13C-n.m.r.-line patterns of these oligosaccharide derivatives and the corresponding polysaccharides show striking differences dependent upon the anomeric configurations of the KDO residues. These differences may be used for the identification, by visual or computer-assisted pattern analysis, of the anomeric configurations of KDO-residues in oligo- or poly-saccharides. Thus, it was confirmed that the KDO residues in the K 13, K 20, and K 23 polysaccharides have the beta anomeric configuration, whereas those in the LP 1092 polysaccharide have the alpha anomeric configuration.

Carbohydrate Conformation↗
PubMed1985

The preparation and use of a carrier-bound acceptor for the determination of sialyl transferase activity in serum.

Agarose-bound asialofetuin functions as an insoluble sialyl group acceptor in a simplified assay for sialyl transferase (CMP-neuraminate: D-galactosyl-glycoprotein N-acetylneuraminyl transferase; EC 2.4.99.1) in serum. Since sialyl transferase levels in serum are elevated in a large number of malignant conditions, the simplified assay is of use for clinical monitoring in tumour therapeutic programmes.

Asialoglycoproteins↗
PubMed1981

Effect of subinhibitory concentrations of mecillinam on the serum susceptibility of Escherichia coli strains.

For serum-resistant clinical isolates of Escherichia coli were grown in the presence of various subinhibitory concentrations of mecillinam or pivmecillinam and then exposed to the bactericidal action of human serum. All strains became more serum susceptible as a result of pregrowth in medium containing mecillinam, but the concentration of antibiotic needed to produce the effect varied according to the strain being used. Production of ovoid or round cells was a prerequisite for sensitization to serum. Growth in the presence of mecillinam did not alter the response to serum of a serum-susceptible E. coli strain.

Amdinocillin↗