Structural and immunochemical studies on the lipopolysaccharide of the ‘T-antigen’-containing mutant Proteus mirabilis R14/1959

Abstract In DOC-PAGE, lipopolysaccharide (LPS) of Proteus mirabilis R14/1959 (Rb-type) mutant showed a ladder-like migration pattern indicating the presence of a high molecular weight polysaccharide chain. The isolated polysaccharide, called T-antigen because of similarity with the T1 chain of Salmonella friedenau LPS, contained d -glucose, d -galacturonic acid ( d -GalA), and d -GlcNAc in molar ratios 2:1:1 and was structurally different from the O-antigen of the parental S-strain P. mirabilis S1959 but identical to the O-antigen of another S-strain Proteus penneri 42. The importance of a d -GalA( l -Lys)-containing epitope, most likely present in the core region of LPS, and of GalA present in the T-antigen chain in manifesting the serological specificity of P. mirabilis R14/1959 were revealed using rabbit polyclonal homologous and heterologous R- and O-specific antisera and the appropriate antigens, including synthetic antigens which represent partial structures of various Proteus LPS.     

Serum concentration of prolactin, gastrin and glycocholic acid in patient with peptic ulcer treated with ranitidine

In 66 patients with peptic ulcer (11 with gastric ulcer, 55 with duodenal ulcer, 19 women, 47 men) the serum concentrations of prolactin, dehydrocholic acid and gastrin were determined. The studies were repeated after treatment with ranitidine: in 50 patients after three weeks and in 40 patients after another 30 days. During the first period ranitidine 2 x 150 mg was administered, while during the second period the dose was 1 x 150 mg. The results were compared with those obtained from 120 healthy subjects. Before starting the treatment prolactin levels were significantly higher than those in the control group. During the treatment a significant decrease of the levels was observed. Similar changes of prolactin concentrations were found in the group of 39 men with duodenal ulcer isolated from the studied patients, who were compared with a group of 50 healthy men. It was not found that the development of peptic ulcer and the treatment with ranitidine exerted and effect on the changes of gastrin and dehydrocholic acid concentrations.     

Characterization of monoclonal antibodies recognizing three distinct, phosphorylated carbohydrate epitopes in the lipopolysaccharide of the deep rough mutant I-69 Rd−/b+ of Haemophilus influenzae

Monoclonal antibodies against the lipopolysaccharide (LPS) of the deep rough mutant I-69 Rd⁻/b⁺ of Haemophilus influenzae were obtained after immunization of mice with sheep erythrocytes which had been coated with de- O -acylated LPS. Characterization of antibodies was performed by enzyme immuno assay (EIA) using LPS or neoglycoconjugates containing partial structures of LPS as solid-phase antigens and by haemagglutination with sheep erythrocytes coated with de- O -acylated LPS. Binding data were confirmed by EIA inhibition experiments using deacylated LPS or synthetic partial structures thereof. Three antibodies were specific for 3-deoxy- d - manno -octulopyranosonic acid- (Kdo) 5-phosphate, one for Kdo-4-phosphate, and one required, in addition to a Kdo-phosphate, parts of the phosphorylated glucosamine backbone of lipid A. All antibodies also bound in (i) Western blots to bacterial whole-cell lysates or isolated LPS separated by SDS–PAGE, (ii) bacterial colony blots, and (iii) immunofluorescence with live bacteria. The latter result indicated that Kdo-4- and Kdo-5-phosphate are synthesized by the bacteria and are not the result of phosphate migration.     

Discrepancies between flow cytometric analysis and [3H]thymidine incorporation in stimulated lymphocytes

The DNA synthesis system of freshly isolated tonsillar lymphocytes and those stimulated by phytohaemagglutinin were compared by different methods. Both cell populations had high DNA polymerase α and thymidine kinase activities, as well as a high rate of incorporation of [³H]thymidine into DNA. However, the two cell populations differed when their DNA distributions were compared by flow cytometry. Freshly isolated cells contained many less (6%) cells in S phase than were found in phytohaemagglutinin-stimulated lymphocytes (18%) as detected by flow cytometry. The labelling of different subpopulations of lymphocytes was studied by sorting them electrically with a fluorescence-activated cell sorter. Analysis of the radioactivity of [³H]thymidine pulse-labelled cells, sorted according to their DNA content, showed that cells in the G₁ peak of DNA distribution had a significant amount of incorporated [³H]thymidine. Sorting of cells according to their size (i.e., by light scattering) revealed that only large cells were labelled with [³H]thymidine.     

Site-specific integration of the temperate bacteriophage phi adh into the Lactobacillus gasseri chromosome and molecular characterization of the phage (attP) and bacterial (attB) attachment sites.

The temperate bacteriophage phi adh integrates its genome into the chromosomal DNA of Lactobacillus gasseri ADH by a site-specific recombination process. Southern hybridization analysis of BclI-digested genomic DNA from six relysogenized derivatives of the prophage-cured strain NCK102 displayed phage-chromosomal junction fragments identical to those of the lysogenic parent. The phi adh attachment site sequence, attP, was located within a 365-bp EcoRI-HindIII fragment of phage phi adh. This fragment was cloned and sequenced. DNA sequence analysis revealed striking features common to the attachment sites of other site-specific recombination systems: five direct repeats of the sequence TGTCCCTTTT(C/T) and a 14-bp inverted repeat. Oligonucleotides derived from the sequence of the attP-containing fragment enabled us to amplify predicted junction fragment sequences and thus to identify attL, attR, and attB. The core region was defined as the 16-bp sequence TACACTTCTTAGGAGG. Phage-encoded functions essential for site-specific insertion of phage phi adh were located in a 4.5-kb BclI fragment. This fragment was cloned in plasmid pSA34 to generate the insertional vector pTRK182. Plasmid pTRK182 was introduced into L. gasseri NCK102 by electroporation. Hybridization analysis showed that a single copy of pTRK182 had integrated at the attB site of the NCK102 erythromycin-resistant transformants. This is the first site-specific recombination system described in lactobacilli, as well as the first attP-based site-specific integration vector constructed for L. gasseri ADH.     

High level of surface CD4 prevents stable human immunodeficiency virus infection of T-cell transfectants.

CD4 is the principal receptor for the human immunodeficiency virus (HIV). We have isolated and studied CD4-expressing tumor cell clones made by expressing CD4 in the T-cell tumor line HSB. Two clones, one designated HSBCD4, a clone expressing low levels of CD4, and the other, HSB10xCD4, a high-expresser CD4+ clone, were studied for their ability to bind and replicate HIV. In contrast to many other CD4+ cells that down-modulate CD4 following HIV infection, the HSB10xCD4 clones continued to express high levels of surface CD4 following infection with HIV. Unlike infection of HSBCD4 or many other human CD4+ cells, HIV infection of HSB10xCD4 clone was short lived: p24 antigen, provirus, or coculturable virus was present for less than 14 days following infection with several strains of HIV-1 or with HIV-2. When infection was initiated by transfection of proviral DNA, high and low CD4 expressers initially produced p24 antigen at approximately the same level. However, high CD4 expressers produced coculturable virus only during the first few days following transfection, whereas low CD4 expressers transfected with HIV continued to produce virus beyond 6 weeks. Monoclonal antibody-mediated down-modulation of CD4 surface expression on HSB10xCD4 clones permitted these formerly HIV-resistant cells to become persistently infected with HIV. Thus, high concentrations of CD4 on the surface of an HIV-infected cell prevent persistent HIV infection of CD4+ cells.