RESUMEN
The complex interaction of leukemia inhibitory factor (LIF) with its specific receptor present on the cell surface, in isolated membranes and in solution, has been examined in detail. Several aspects of this complexity have been highlighted, including the presence of high- and low-affinity murine LIF receptors, biphasic dissociation of human LIF from apparently homogeneous high- or low-affinity human LIF receptors, and unusual species cross-reactivity. The unusual species cross-reactivity observed between murine and human LIF has also been exploited to map an important receptor binding epitope on human LIF.
Asunto(s)
Membrana Celular/metabolismo , Inhibidores de Crecimiento/metabolismo , Interleucina-6 , Linfocinas/metabolismo , Receptores de Citocinas/metabolismo , Animales , Humanos , Cinética , Factor Inhibidor de Leucemia , Subunidad alfa del Receptor del Factor Inhibidor de Leucemia , Ratones , Unión Proteica , Receptores OSM-LIF , Proteínas Recombinantes de Fusión/metabolismo , Solubilidad , Especificidad de la EspecieRESUMEN
Four murine monoclonal antibodies which reacted with a (2----8)alpha-linked sialic acid polysaccharide were produced. Three of the antibodies reacted specifically with Neisseria meningitidis serogroup B and Escherichia coli K-1 polysaccharide antigens, whereas one antibody cross-reacted with N. meningitidis group C polysaccharide antigen, a (2----9)alpha-linked homopolymer of sialic acid. By using the most avid antibody (MB 62), a latex particle agglutination test was developed which could detect capsular polysaccharide at 10 ng/ml. It also detected antigen in the cerebrospinal fluid (CSF) of all seven N. meningitidis group B- and two E. coli K-1-infected patients, whereas 57 control CSF samples, including 8 from neonates, were negative. Cultures of 21 N. meningitidis group B strains, 7 E. coli K-1 strains, and 1 Moraxella nonliquefaciens strain gave a positive result, whereas 53 strains from other serogroups were all negative. In a separate clinical evaluation, the overall sensitivity of the latex particle agglutination test was 81% (22 of 27) with fresh CSF samples, 48% (15 of 31) with stored CSF samples, and 94% (32 of 34) with blood cultures. No false-positive reactions were recorded with 165 control CSF samples, and the specificity with blood cultures was 99.4% (519 of 522).
Asunto(s)
Anticuerpos Monoclonales/inmunología , Antígenos Bacterianos/análisis , Escherichia coli/inmunología , Neisseria meningitidis/inmunología , Pruebas de Aglutinación , Animales , Anticuerpos Antibacterianos/inmunología , Cápsulas Bacterianas , Líquido Cefalorraquídeo/inmunología , Contrainmunoelectroforesis , Reacciones Cruzadas , Escherichia coli/aislamiento & purificación , Infecciones por Escherichia coli/diagnóstico , Humanos , Recién Nacido , Pruebas de Fijación de Látex , Meningitis Meningocócica/diagnóstico , Ratones , Moraxella/inmunología , Neisseria meningitidis/aislamiento & purificación , Polisacáridos Bacterianos/inmunología , Valor Predictivo de las PruebasRESUMEN
During germination of barley grains, the cell walls of the starchy endosperm are degraded by (1-->3,1-->4)-beta-glucanases (EC 3.2.1.73) secreted from the aleurone and scutellar tissues. The complete sequence of the aleurone (1-->3,1-->4)-beta-glucanase isoenzyme II comprises 306 amino acids and was determined by sequencing nine tryptic peptides (110 residues) and aligning them with the amino acid sequence deduced from a cDNA clone encoding the 291 NH(2)-terminal residues. Although no amino acid sequence homology with a bacterial (1-->3)(1-->4)-beta-glucanase is apparent, close to 50% homology is found with two large regions of a (1-->3)-beta-glucanase from tobacco pith tissue. The gene for barley (1-->3,1-->4)-beta-glucanase isoenzyme II shares with that for the alpha-amylase isoenzyme 1 a strongly preferred use of codons with G and C in the wobble position (94% and 90%, respectively). Both enzymes are secreted from the aleurone cells during germination. Such one-sided codon usage is not characteristic for the gene encoding the (1-->3)-beta-glucanase of tobacco pith tissue or the hor2-4 gene encoding the B(1) hordein storage protein in the endosperm.