PubMed Health⌕ Search

Biomedical subjects

R Verdon

Publications and source records attributed to R Verdon.

26 records · Page 2Linked to original sources
PubMed1993

Shigella flexneri transformants expressing type 1 (mannose-specific) fimbriae bind to, activate, and are killed by phagocytic cells.

Shigella flexneri M90T (invasive) and BS176 (noninvasive) are typical nonfimbriated organisms that do not bind to or activate phagocytic cells. We demonstrate that S. flexneri M90Tp and BS176p, obtained by transformation of the strains named above with the cluster of genes encoding type 1 (mannose-specific) fimbriae of Escherichia coli, express the functional fimbriae, as shown by electron microscopy, by binding of antifimbria antibodies and by yeast cell aggregation. The transformants, but not the parental strains, bound to human granulocytes and mouse peritoneal macrophages. This binding was inhibited by methyl alpha-D-mannoside but not by methyl alpha-D-galactoside. The bound bacteria induced oxidative burst activation and degranulation of the granulocytes in vitro. With mouse peritoneal macrophages, the binding of the fimbriated bacteria induced degranulation in vitro. Injection of the bacteria into mouse peritoneum also induced degranulation of the macrophages in vivo; no such effect was observed with the nonfimbriated strains. The bound fimbriated transformants were effectively killed by the human granulocytes in vitro in the absence of opsonins or after opsonization with human anti-S. flexneri antiserum. The nonfimbriated strains were killed only after opsonization. These results provide further evidence for the role of type 1 fimbriae in lectin-mediated nonopsonic phagocytosis.

Animals↗
PubMed1992

[Diarrhea in AIDS. Group AIDS GIT].

Gastrointestinal (GI) infections are frequent in AIDS patients. The frequency and type of opportunistic GI infections are exactly the same in homosexuals and heterosexuals. Diarrhoea is the usual sign of GI infection, and its mechanism seems to combine a secretory component and a malabsorption. Although a number of pathogens can be isolated, in many cases the diarrhoea cannot be explained by an infection or a lesion. The hypothesis of a primary HIV infection in the epithelium of the small bowel and colon has not been confirmed by immunofluorescence and molecular hybridization. The HIV virus has been found in the GI mucosa, but it was probably carried by the immune cells in general circulation (CD4 lymphocytes and macrophages) which subsequently colonize the chorion of the mucosa.

Acquired Immunodeficiency Syndrome↗
PubMed1992

A model of interaction between Entamoeba histolytica and Shigella flexneri.

The establishment of a relationship between Entamoeba histolytica and certain bacteria may contribute to the expression and/or enhancement of the pathogenicity of this parasite. Recent experiments have shown that bacteria expressing mannose-binding lectins on their surface could attach to mannose-containing molecules on the surface of amoebae. In this study, we established a model of interaction between. E. histolytica and Shigella flexneri. Using well-characterized mutants of S. flexneri, we studied the role of type I pili expression and the invasive phenotype of S. flexneri in the interaction between amoebae and the bacteria. Type I pili expression allowed attachment and subsequent internalization of S. flexneri by amoebae, these events were not observed in isogenic strains that did not express type I pili. Invasive as well as non-invasive variants of S. flexneri expressing type I pili were slowly digested by amoebae following internalization. Morphological studies showed that the specific features of the interaction depend on the dynamics of the distribution of mannose residues on the amoebic membrane during the interaction.

Animals↗
PubMed1992

[Cryptosporidiosis].

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Upper gastrointestinal tract infections in AIDS. AIDS GIT Group.

Upper gastrointestinal tract infection in AIDS is a complex multifactorial process. The approach to diagnostic evaluation can be based upon knowledge of the large spectrum of bacteria, viruses and protozoa involved. The availability of effective therapy is the most decisive factor in determining the duration of upper gastrointestinal tract infections in AIDS patients. Awareness of the clinical, epidemiological, immunological and therapeutic aspects should help to direct the diagnostic evaluation of these patients and to highlight areas of research.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[Fatal Lyell's syndrome caused by griseofulvin].

A case of toxic epidermolysis (TE) with a fatal outcome is reported. It occurred after administration of 500 mg griseofulvin twice daily in a 19-year-old female patient. She developed the first skin lesions on the sixth day of treatment. All the body surface was involved, except for the scalp. Several complications arose in the course of the disease, thrombocytopaenia, lymphocytopaenia, rhabdomyolysis, and non cardiogenic pulmonary oedema. Death occurred as a result of multiple organ failure following septic shock associated with adult respiratory distress syndrome. The pathogenesis of these complications and the major therapeutic difficulties encountered are discussed. The involvement of griseofulvin in TE has only been reported once before. The arguments in favour of its involvement in the present case are discussed.

Adult↗