Biomedical subjects

A C Larsson

Publications and source records attributed to A C Larsson.

3 recordsLinked to original sources

PubMed1988

An amplification technology for improving sensitivity when measuring components in biological samples.

A new technology for improving the sensitivity in measuring components in biological samples is described. The method is based on the use of spherical microbeads (detection beads) which contain a large amount of immobilized enzyme and a reagent with biospecific affinity for the component to be detected. These microbeads have been used in a 'sandwich reaction' for visualization of P-fimbriated Escherichia coli which has a known receptor structure (Gal(alpha 1-4)Gal(beta)). In the initial step the bacteria were enriched on a solid support (e.g., a plastic film or beads (greater than 150 microns)) to which the receptor structure had been covalently bound. In the next step detection beads coupled with enzyme and receptor structure were added and finally a chromogenic substrate for the enzyme was used for visualization. A sensitivity of 10(5) bacteria/ml was reached. The detection beads are of general utility and might be useful for the detection of lectins on other pathogens.

Agglutination Tests↗

PubMed1987

Receptor-specific agglutination tests for detection of bacteria that bind globoseries glycolipids.

Specific binding to the globoseries of glycolipid receptors explains the adherence of uropathogenic Escherichia coli to host cells. The minimal receptor disaccharide Gal alpha 1----4Gal beta [galactose alpha (1----4)galactose beta] is recognized by most attaching clinical isolates. However, wild-type isolates can express adhesins with several different receptor specificities. Bioassays do not permit separate analysis of each receptor specificity, since the target cells contain multiple potentially receptor-active molecules. In this study, bacterial adhesins were analyzed by using receptors immobilized into latex beads in one of two ways. In one way, di- and trisaccharides were covalently linked via a spacer arm to latex beads coupled with bovine serum albumin. In the other way, receptor-active glycolipids were coated onto the bovine serum albumin-latex beads. The latex beads were subsequently used for agglutination by using type strains with known receptor specificity. The composition was optimized regarding receptor structure and size of latex beads. Gal alpha 1----4Gal beta was as active as the trisaccharide derivative Gal alpha 1----4Gal beta 1----3glucose or Gal alpha 1----4Gal beta 1----3glucosamine. Among the natural glycolipids tested, globotetraosylceramide was the most active. Subsequently, the sensitivity and specificity of the Gal alpha 1----4Gal beta-latex and globotetraosylceramide-latex reagents were compared for 733 E. coli urinary isolates. Hemagglutination of human erythrocytes was used as the positive standard. No significant difference in the specificity or sensitivity of the latex reagents was found; the sensitivity ranged from 86%, when isolates agglutinating human erythrocytes of blood groups P1 and p were included, to 93%, when those isolates agglutinating erythrocytes of blood group p were excluded. These reagents provide tools for bacterial identification in patients with urinary tract infection.

Adhesins, Escherichia coli↗

PubMed1987

Binding to galactose alpha 1----4galactose beta-containing receptors as potential diagnostic tool in urinary tract infection.

The diagnosis of urinary tract infection is based largely on quantitative urine cultures. The usefulness of qualitative information about the virulence of the infecting bacteria remains undefined. Ability to attach to human uroepithelial cells is one characteristic of the pyelonephritogenic clones, as well as a virulence factor per se. The identification of host cell receptors for attaching bacteria has permitted the construction of agglutination tests for simple detection of bacterial binding properties. In the present study, the reactivity with Gal alpha 1----4Gal beta-latex [galactose alpha (1----4)galactose beta-latex] and globotetraosylceramide-latex was analyzed for strains from patients with acute pyelonephritis (n = 135), acute cystitis (n = 121), and asymptomatic bacteriuria (n = 119) and from the fecal flora of healthy children (n = 120) and compared with agglutination of human blood group P1 and p, as well as guinea pig, erythrocytes. The reactivity by bioassay and the receptor-specific assays were significantly correlated. The frequency of positive reactions among the pyelonephritis isolates was 78.5% with the globotetraosylceramide-latex reagent, compared with 41% for the cystitis isolates, 25% for the asymptomatic bacteriuria isolates, and 13% for the fecal isolates. The combination of bioassays and receptor-specific assays increased the resolution of adhesins. Thus, adhesins reacting with human p erythrocytes frequently were coexpressed with Gal alpha 1----4Gal beta-specific adhesins. The receptor-specific assays provide a refined reagent to resolve bacterial binding specificities, as well as a potential tool for clinical diagnosis.

Adhesins, Escherichia coli↗