Reliability of the Widal tube agglutination test has been the subject of many controversies over the years. !is study was performed to assess the effect of certain modifications on the performance of Widal test in a novel microplate assay. Sera from 37 patients (21 males; 16 females) (mean age 28 + 7 years) were tested in the Immunology Unit at King Khalid University Hospital, Riyadh. Among them were 26 patients with suspected typhoid fever and 11 had bacteriologically confirmed diagnosis of Salmonella infection. The modifications included either the use of 0.5% bovine serum albumin (BSA), absorption of sera with sheep red blood cells (SRBC) or heat inactivation of sera. Compared with Widal tube agglutination test, microplate assay with SRBC absorption of the sera from patients with suspected typhoid fever was not only associated with enhancement of detection titers for both H (p < 0.001) and O (p < 0.005) Salmonella agglutinins but also the percentage of reactivity. !e presence of BSA augmented detection titers for Salmonella H agglutinins (p < 0.02) only. Heat inactivation of sera however was found to be associated with reduction in the detectable titers for both H (p < 0.03) and O (p < 0.01) agglutinins. Increased titers of Salmonella agglutinins were also evident in 11 patients with confirmed diagnosis of Salmonella infection. The novel microplate agglutination assay using the SRBC absorption was associated with enhancement in Widal test reactivity and appears to be a useful alternative for the diagnosis of Salmonella infection.
Expression of N-cadherin an adhesion molecule of the cadherin family, in tumor cells is associated with their increased invasive potential. Many studies suggested the role of N-linked oligosaccharides as important factors that contribute to metastasis by influencing tumor cell invasion and adhesion. N-cadherin is a heavily glycosylated protein. We have analysed the carbohydrate profile of this protein synthesized in human melanoma cell lines: WM35 from the primary tumor site and WM239, WM9, and A375 from different metastatic sites. N-cadherin was immunoprecipitated with anti-human N-cadherin polyclonal antibodies. Characterisation of its carbohydrate moieties was carried out by SDS/PAGE electrophoresis and blotting, followed by im- munochemical identification of the N-cadherin polypeptides and analysis of their glycans using highly specific digoxigenin or biotin labelled lectins. The positive reaction of N-cadherin from the WM35 cell line with Galanthus nivalis agglutinin (GNA), Datura stramonium agglutinin (DSA) and Sambucus nigra agglutinin (SNA) indicated the presence of high-mannose type glycans and biantennary complex type oligosac- charides with a2-6 linked sialic acid. N-cadherin from WM239, WM9, and A375 cell lines gave a positive reaction with Phaseolus vulgaris leukoagglutinin (L-PHA) and lotus Tetragonolobus purpureas agglutinin (LTA). This indicated the presence of tri- or tetra-antennary complex type glycans with a-fucose. In addition, N-cadherin from WM9 (lymphomodus metastatic site) and A375 (solid tumor metastatic site) contained complex type chains with 2–3 sialic acid (positive reaction with Maackia amurensis agglutinin — MAA). The results demonstrated that N-glycans of N-cadherin are altered in metastatic melanomas in a way characteristic for invasive tumor cells.
The relationship between the prevalence of normal serum agglutinins and precipitins to Aeromonas hydrophila and A. veronii biotype sobria in carp and the sensitivity of the fish to infection with these bacteria was studied. The presence of these antibodies depended on carp population and on individual fish. No correlation between the prevalence of agglutinins and the sensitivity of carp to infection was found. On the contrary, the fish having the precipitins to particular Aeromonas strains revealed significantly lower sensitivity to infections with the respective homologous strains than those without the precipitins.
The mannose-binding agglutinin from bulbs of Lycoris aurea (LAA) agglutinates rabbit but not human erythrocytes. The molecular mass of the monomer in SDS/PAGE is 12 kDa while the apparent molecular mass in gel filtration is 48 kDa, indicating that LAA is a homotetramer. The full-length cDNA of LAA contains 683 bp with an open reading frame encoding a protomer of 162 amino-acid residues. Hydrophobic Cluster Analysis and molecular modeling of the 109-residue mature polypeptide suggested a similar secondary and tertiary structure to those of Narcissus pseudonarcissus agglutinin (NPA). Molecular docking revealed that, besides the three mannose-binding sites common among Amaryllidaceae lectins, LAA also contains a fourth unique mannose-binding site formed by a tryptophan cluster. The existence of four mannose-binding sites in each monomer of LAA is very unusual and has only been reported for NPA earlier.