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Biomedical subjects

R Girardot

Publications and source records attributed to R Girardot.

14 recordsLinked to original sources
PubMed2004

[Factors predictive of mortality in Ebstein's anomaly].

Nearly 150 years after the description of Ebstein's anomaly the prognostic factors are not well known. Besides the foetal and neonatal forms which carry a poor prognosis the adult forms are often well tolerated and pose the difficult problem of management. This was a retrospective study of 73 patients with this malformation followed up between 1967 and 2002 at the University Hospital of Bordeaux. There were 14 deaths (19%) half of which (7) occurred during the first 3 months of life. The factors predictive of mortality (p<0.05) were: age, associated malformations, Classes III-IV of the New York Heart Association, cardiac failure, malaises, cyanosis, a raised cardiothoracic index, and a high mitro-tricuspid displacement indexed to body surface area. Supraventricular arrhythmia and the Wolff-Parkinson-White syndome do not seem to be associated with extramortality. Surgery, with reference to published studies, seems to improve survival, functional status and decrease the prevalence of arrhythmias. It would appear to be justified to propose surgery when functional status declines or when signs of poor prognosis are observed.

Adolescent↗
PubMed2004

[Diagnostic and therapeutic value of lymphography in persistent postoperative chylothorax].

Chylothorax is a rare but generally severe complication of surgery of congenital heart disease. The authors report the clinical history of a young boy with complex congenital heart disease operated on several occasions and who developed severe and recurrent unilateral chylothorac after a bicavo-bipulmonary derivation. Conservative treatment followed by continuous somatostatin infusion was ineffective. Diagnostic Lipiodol lymphography was required before the chylothorax was cured. The authors describe management of this difficult case and discuss the therapeutic possibilities with reference to a brief review of the literature.

Child↗
PubMed1998

Characterization of a novel structural member, LukE-LukD, of the bi-component staphylococcal leucotoxins family.

A new member of the staphylococcal bi-component leucotoxins family, LukE (32 kDa) and LukD (34.3 kDa) has been characterized from Staphylococcus aureus strain Newman. LukE was 58-68% identical with the class S proteins, whereas LukD was 71-77% identical with the class F proteins of the family. A partial immunoreactivity with the various affinity-purified antibodies specific for the other proteins was observed. Immunoprecipitation assay and gene probing confirmed a 30% frequency among human clinical isolates, differing from the distribution of the other known leucotoxins (P<0.005). LukE+LukD was as effective as the Panton-Valentine leucocidin for inducing dermonecrosis when injected in the rabbit skin, but not hemolytic and poorly leucotoxic compared to other leucotoxins expressed by Staphylococcus aureus.

Amino Acid Sequence↗
PubMed1996

Characterisation of an enterotoxin-negative, cytotoxin-positive strain of Clostridium sordellii.

In ileal loop assay, ELISA and anion-exchange column chromatography, Clostridium sordellii strain 6018 was shown to produce a cytotoxin, but no detectable enterotoxin. DNA sequence and polymerase chain reaction analyses indicated that the lack of enterotoxin activity is not due to a lack of gene transcription, but to lack of a major portion of the enterotoxin gene. This is the first characterisation of such a strain.

Amino Acid Sequence↗
PubMed1994

Hyperphosphorylation of calnexin, a chaperone protein, induced by Clostridium difficile cytotoxin.

Exposure of McCoy cultured cells to Clostridium difficile cytotoxin B or okadaic acid (OA), a potent phosphatase inhibitor, results in similar morphological changes. Using two-dimensional gel electrophoresis, we have detected a protein of approximately 77 kDa, with a pI of 4.5 (termed pp77) which is hyperphosphorylated in both cases. The level of phosphorylation of pp77 is increased by 293% and 35% after treatment with C. difficile cytotoxin B or OA, respectively. This protein was identified by microsequencing as calnexin, a protein which exhibits the characteristics of an endoplasmic reticulum (ER) chaperone.

Amino Acid Sequence↗
PubMed1994

Clostridium sordellii cytotoxin induces phosphorylation of an 80,000 mol. wt protein in McCoy cultured cells.

The cytotoxins from Clostridium difficile (toxin B) and Clostridium sordellii (toxin L) induce rounding of cultured cells. The cellular effects induced by these two cytotoxins are clearly distinct, suggesting that both toxins use a similar, but not identical mechanism for cell intoxication. We have employed the technique of two-dimensional PAGE for the separation of 32P-labelled cell lysates of McCoy cultured cells to investigate changes in the phosphorylation status of cellular proteins after treatment with toxin B and with toxin L. The two-dimensional electrophoresis patterns suggest the implication of an 80,000 mol. wt cellular protein (named pp80c) in the cytopathic action of the cytotoxin from C. sordellii. This protein shows immunoreactivity with non-muscle caldesmon. Toxin B, however, does not affect the phosphorylation of pp80c, but alters the phosphorylation of another cellular protein, pp77, indicating another mechanism for cell intoxication. In addition, our experiments suggest that the mechanism of action of okadaic acid, a phosphatase inhibitor which causes cell rounding similar to that induced by C. sordellii, and these two cytotoxins are different.

Bacterial Toxins↗
PubMed1993

Effect of okadaic acid on the cytotoxic activity of Clostridium difficile toxin B and Clostridium sordellii toxin L.

Clostridium difficile toxin B and Clostridium sordellii toxin L, which are immunologically related toxins, possess a cytotoxic activity inducing depolymerization of microfilaments and cellular retraction of cell bodies that are different for toxin B- and toxin-L-treated cells. The biological mechanisms responsible for these effects are unknown, but a previous study revealed that both toxins induce modification of phosphorylation of cellular proteins extracted from toxin B- and toxin L-treated cells without changes in protein kinase C activity or cAMP concentration. In the present study, we have investigated the effect of okadaic acid, an inhibitor of protein phosphatases, on the cytotoxic activity of toxins B and L in MacCoy cells. Firstly, we reveal by cytotoxic assay and staining of F-actin that okadaic acid (1 microM or higher) induces depolymerization of microfilaments and cellular morphological modifications which are similar to that of cells treated with toxin L. Secondly, we show that 1 microM okadaic acid potentials the cytotoxic activity of toxin L but not of toxin B. These observations suggest that the cytotoxic mechanisms induced by okadaic acid and toxin treatment are partly common, indicating that an increase in phosphorylation favors the cytotoxicity of toxin L. Since okadaic acid had no influence on the cytotoxicity of toxin B, we suggest that toxin B and L, alter the cells by different cellular biological mechanisms.

Actins↗
PubMed1992

Comparative study of immunological properties and cytotoxic effects of Clostridium difficile toxin B and Clostridium sordellii toxin L.

We compared the immunological properties and cytotoxic effects of Clostridium difficile toxin B and Clostridium sordellii toxin L. These two cytotoxins are immunologically related in that the cytotoxic effect of either toxin can be neutralized by the polyclonal antiserum prepared against either cytotoxin. On the other hand, polyclonal antiserum prepared against Clostridium difficile enterotoxin A did not cross-react with the cytotoxins B and L when tested by cytotoxic neutralization test nor by double immunodiffusion assay. However, despite this immunological relationship between toxins B and L, the morphological modifications observed in MacCoy cells induced by treatment with these cytotoxins are clearly distinct. We describe the first quantitative analysis of specific cellular parameters which illustrates the morphological differences induced by these cytotoxins. Moreover, immunocytochemical experiments show that, whereas disruption of microfilaments is observed with toxin B- and L-treatments, alterations of F-actin network are different in the cells treated with toxin B or L. The observation that the cellular modifications induced by toxin B- and toxin L-treatment differ suggests that the molecular mechanisms involved in the respective cytotoxicities are also likely to be different.

Actin Cytoskeleton↗
PubMed1990

Fast purification of Clostridium sordellii cytotoxin.

We have developed a rapid method for the purification of proteins, combining titration curve analysis with a two-step column chromatographic procedure. We have used this approach to purify the cytotoxin (L toxin) from Clostridium sordellii. We have also determined the amino acid composition of this cytotoxin. This toxin has a pI value of 4.20 and an Mr of 260,000, reduction of which results in a band of Mr 43,000 on sodium dodecyl sulphate polyacrylamide gel electrophoresis. Since both the proteins of Mr 260,000 and 43,000 are recognized by the polyclonal anti-C. sordellii L toxin, which neutralizes the L toxin cytotoxicity, we propose a hexameric structure for the protein of Mr 260,000, each subunit being Mr 43,000.

Amino Acids↗
PubMed1990

Enzyme immunoassay (ELISA) for detection of Clostridium difficile toxin B in specimens of faeces.

Antisera against Clostridium difficile toxin B were prepared in sheep and rabbit and were used in indirect and sandwich enzyme-linked immunosorbent assays (ELISA) for the detection of toxin B. Polyvinyl chloride and polystyrene microtitration plates were tested as solid phases for the assay. Both assays had a lower limit of detection for toxin B of 1 ng/ml. They were used to detect the presence of toxin B in 210 human faecal specimens and also in the culture supernatant fluids of C. difficile strains isolated from the faecal samples. There was a close correlation between the results of sandwich ELISA and those of cytotoxicity tests and isolation of C. difficile. Our sandwich ELISA method seems to be useful as a presumptive test for detection of C. difficile toxin B.

Bacterial Proteins↗
PubMed1989

Clostridium difficile toxin B: characterization and sequence of three peptides.

The cytotoxin, also named toxin B, was isolated from a toxigenic strain of Clostridium difficile, purified to homogeneity and partially characterized. The purification procedure included ultrafiltration followed by anion-exchange chromatography. We noticed that a non-specific nucleic material eluted with the protein during the purification. The presence of these nucleic acids appeared to be important for the toxic activity of the protein. Some characteristics of the cytotoxin were examined, especially the amino acid composition and the sequence of three tryptic fragments.

Amino Acid Sequence↗
PubMed1985

Effect of the cytotoxin of Clostridium difficile on cultured hepatoma cells.

Clostridium difficile is the major etiologic agent of human pseudomembranous colitis. It produces two toxins: an enterotoxin and a cytotoxin. In cultured hepatoma cells, at very low doses, the cytotoxin inhibits the incorporation of precursors into biological macromolecules. Protein synthesis is more affected than RNA and DNA synthesis. The toxin also induces severe alterations of the cell morphology consisting in damages to the cytoskeleton and to the cell shape.

Animals↗
PubMed1984

A new purification procedure for Clostridium difficile enterotoxin.

Clostridium difficile produces two toxins, an enterotoxin and a cytotoxin. The enterotoxin was purified using fast methods (tangential flow filtration, fast protein liquid chromatography). The purified enterotoxin is composed of two subunits (A1 = 41,500, A2 = 16,000) and its pI is 3.5.

Chromatography, Liquid↗