Search PubMed⌕ Search

Biomedical subjects

D Poulain

Publications and source records attributed to D Poulain.

At least 55 records · Page 3Linked to original sources
PubMed1993

Isolation and preliminary characterization of the 14- to 18-kilodalton Candida albicans antigen as a phospholipomannan containing beta-1,2-linked oligomannosides.

Western blot (immunoblot) analysis of Candida albicans germ tube extracts has demonstrated the probable presence of beta-1,2-linked oligomannosides acting as epitopes distributed over a 14- to 18-kDa antigen unreactive to concanavalin A. These conclusions about the existence of these non-mannan-associated oligomannoside species were reinforced in the present study by the demonstration of reactivity of factor serum 5 (Iatron Laboratories) with the same antigen. A monoclonal antibody which reacted in an enzyme immunoassay with beta-1,2-linked oligomannosides converted into neoglycolipids and in Western blotting with the 14- to 18-kDa antigen from yeast and germ tubes, through metaperiodate-sensitive epitopes, was used for further characterization of the molecule. Reducing agents and strong protease digestion, which have deleterious effects on C. albicans proteins and mannoproteins, affected neither the antigenicity nor the relative molecular weight of the molecule. Western blots performed after migration of protease-treated extracts in polyacrylamide gels without sodium dodecyl sulfate (SDS) showed that the 14- to 18-kDa antigen could be negatively charged, whereas metabolic radiolabeling demonstrated that these charges could originate, at least in part, from the presence of phosphorus within the molecule. Chloroform-methanol-water extraction of protease-resistant material led to purification of the 14- to 18-kDa antigen, as determined by SDS-polyacrylamide gel electrophoresis and Western blotting. Metabolic radiolabeling with mannose confirmed the presence of these sugar residues within the purified 14- to 18-kDa antigen (despite its nonreactivity to concanavalin A), whereas radiolabeling with palmitic acid demonstrated its lipopolysaccharidic nature. Together, these results led to the conclusion that the 14- to 18-kDa antigen is a phospholipomannan.

Antibodies, Fungal↗
PubMed1993

Qualitative and quantitative differences in recognition patterns of Candida albicans protein and polysaccharide antigens by human sera.

Cytoplasmic and cell wall proteins and glycoproteins extracted from Candida albicans germ tubes were screened by Western blotting for their ability to differentiate between the serological responses of patients with candidosis and healthy individuals. Molecules of 114, 74 and 65 kDa were not recognized by any sera. Qualitative differences were observed for responses to proteins and glycoproteins from 29 to 60 kDa. Conversely, only quantitative differences were found to high molecular mass glycoproteins. Their recognition by control sera was invariably associated with reactivity against a 14-18 kDa antigen. However, despite a high level of antibodies against high molecular mass mannoproteins, some patients sera failed to react with the 14-18 kDa antigen, or lost this reactivity during the course of the disease.

Adult↗
PubMed1993

Identification of Candida albicans cell wall antigens lost during subculture in synthetic media.

A high variability in reactivity was observed when Candida albicans strains freshly isolated from both patients with candidiasis and asymptomatic carriers were tested against different human sera. The highest reactivity was observed in C. albicans strains isolated from blood cultures. This high reactivity was observed when the isolates were tested against sera from patients with Candida oesophagitis, patients with vulvovaginal candidiasis, or asymptomatic carriers but not against sera from blood donors. The antigenic reactivity of the strongly reactive strains, but not that of the weakly reactive strains, decreased during subculture in synthetic media. Five major components of an apparent molecular mass of > 200, 67-70, 49-52, 33-35 and 29-31 kDa were observed in alpha-mannosidase extracts from C. albicans strains from both blood cultures (Group I) and patients with Candida oesophagitis (Group II) subcultured in synthetic media for different times. Changes in staining intensity through the different subcultures were observed for some bands. Group I strains showed a decrease in staining intensity for bands of > 200 and 67-70 kDa, an increase for bands of 33-35 and 29-31 kDa, but no changes were observed for the band of 49-52 kDa. Group II strains showed opposite changes in banding intensity. A decrease in staining intensity was observed for the proteins of 33-35 and 29-31 kDa, an increase for the protein of 49-52 kDa, and no change in intensity was observed for the band of 67-70 kDa. A component of > 200 kDa showed an irregular expression through the subcultures. The main antigen present in extracts from the first subculture of isolates from Group I and II had a molecular mass of 67-70 kDa. It could be related to the P antigens since it disappeared following subculture of the strains in synthetic media.

Antigens, Fungal↗
PubMed1992

Complete 1H- and 13C-resonance assignments for D-mannooligosaccharides of the beta-D-(1-->2)-linked series released from the phosphopeptidomannan of Candida albicans VW.32 (serotype A).

D-Mannooligosaccharides (dp 1 to > 17) were released by mild acid hydrolysis from the phosphopeptidomannan of a Candida albicans strain of A serotype (VW.32). Among these, mannooligosaccharides ranging from bi- to hepta-ose, which were obtained in appreciable amounts, were structurally investigated and found to belong to the beta-D-(1-->2)-linked series. The occurrence of such compounds has already been reported in other Candida albicans strains. The complete 1H- and 13C-resonance assignments for manno-tri- to manno-hepta-ose are reported and general rules applicable for the 1NMR spectrum analysis of linear mannooligosaccharide of the general structure, beta-D-Man p-(1-->2)-[beta-D-Man p-(1-->2)]n-beta-D-Man p are proposed.

Acids↗
PubMed1992

Cytological immunodetection of yeast glycoprotein secretion.

Expression of antigenic epitopes shared by secreted yeast glycoproteins was studied using specific immunological probes. Application of cytological and ultrastructural methods of immunodetection, employing monoclonal antibodies, permitted us to localize these glycoproteins in the cytoplasm, through the cell wall and at the yeast cell surface. Importance of glycosylation-secretion relationships were evaluated in the secretion process of these molecules. The cell wall crossing and the cell surface distribution of antigenic glycoproteins was described in immunoelectron microscopy and immunofluorescence. Some preferential secretion "ways" were suspected through the yeast cell wall leading to an heterogenous distribution of cell surface glycoproteins destined to be excreted into the medium. Antigenic variability of cell wall glycoproteins expression was discussed in relation with the glycoprotein secretion.

Antibodies, Monoclonal↗
PubMed1992

Evaluation of an enzyme immunoassay using neoglycolipids constructed from Candida albicans oligomannosides to define the specificity of anti-mannan antibodies.

In order to study the respective roles of oligomannoside sequences in the antigenicity of Candida albicans phosphopeptidomannan, a method was developed for constructing neoglycolipids from oligomannosides released by depolymerisation of this molecule. Oligomannosides released by acetolysis were converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin layer chromatography. When coated onto microEIA plates, the neoglycolipids exhibited strong reactions which were dose dependent and were saturable with concanavalin A. Reactivity of neoglycolipids with immunoglobulins were then tested with a panel of monoclonal and polyclonal antibodies reacting with epitopes present in the original phosphopeptidomannan. One of two IgM monoclonal antibodies and two of five monospecific rabbit polyclonal IgG reacted strongly with neoglycolipids therefore providing evidence of the presence of structures mimicking epitopes within the pool of neoglycolipids. When 38 sera from 18 hospital inpatients with various levels of antibodies to Candida albicans were tested, a correlation was observed between the EIA to detect neoglycolipids and the EIA to detect phosphopeptidomannan. Successive sera from all patients showing seroconversion in the immunofluorescence assay had increased EIA signals for neoglycolipids.

Antibodies, Fungal↗
PubMed1992

Mapping of Candida albicans oligomannosidic epitopes by using monoclonal antibodies.

Six monoclonal antibodies (MAbs) from various laboratory sources (EB-CA1, EB-CA2, H5, AF1, C6, and 5B2), reacting with the polysaccharidic moieties of Candida albicans mannoproteins, were used for epitope mapping by an enzyme-linked immunosorbent assay (ELISA) with neoglycolipids and by Western blotting (immunoblotting) of a C. albicans germ tube extract. The ELISA involved neoglycolipids constructed from three families of oligomannosides released by sequential depolymerization of C. albicans phosphopeptidomannan by acid hydrolysis (NGLH), beta-elimination (NGLO), and acetolysis (NGLA). All of the MAbs exhibited low reactivities against NGLO. MAbs EB-CA1, EB-CA2, and H5 reacted mainly against NGLA, and MAbs C6 and AF1 recognized mainly NGLH, whereas MAb 5B2 reacted with both families of neoantigens. When this method was compared with Western blotting, strong reactivity to NGLA was associated with the presence of epitopes shared by high-molecular-weight mannoproteins, whereas strong reactivity to NGLH was associated with a reactivity to a family of 14- to 18-kDa antigens. The reactivity of MAb 5B2 was associated with both high-molecular-weight mannoproteins and the 14- to 18-kDa antigens. In relation to the present knowledge about the structure of the C. albicans phosphopeptidomannan oligomannosidic repertoire, these results provide preliminary data concerning the molecular basis of the recognition of mannopyranosyl sequences by MAbs and their distribution among C. albicans mannoproteins.

Antibodies, Monoclonal↗
PubMed1992

Presence of human antibodies reacting with Candida albicans O-linked oligomannosides revealed by using an enzyme-linked immunosorbent assay and neoglycolipids.

In order to study the presence of antibodies directed against Candida albicans O-linked oligomannosides (oligomannosides O) in patient sera, we have developed an enzyme-linked immunosorbent assay (ELISA) involving neoglycolipids constructed with these residues (NGLO). Oligomannosides O released by mild alkaline degradation of the C. albicans cell wall phosphopeptidomannan (PPM) contained one to seven mannose residues, among which the quantitatively major components, mannobiose and mannotriose, were shown by 1H nuclear magnetic resonance to contain exclusively alpha (1-2) linkages. The pool of oligomannosides was converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin-layer chromatography. We have tested against these neoantigens, coated on ELISA plates, 15 pairs of sera corresponding to individual seroconversions observed in 15 patients during the course of a mycological and serological survey of candidiasis. For all patients, seroconversions resulted in an increased level of antibodies against NGLO. A significant correlation was observed between the results of ELISA-NGLO, ELISA involving the original PPM molecule, and routine antibody detection tests, indirect immunofluorescence assay, and cocounterimmunoelectrophoresis. These results therefore demonstrate the synthesis of human antibodies reactive with oligomannosides O constitutive of the C. albicans mannan molecule which have been previously described as exhibiting an inhibitory effect on human lymphocytic proliferation.

Antibodies, Fungal↗
PubMed1992

Retrospective evaluation of two latex agglutination tests for detection of circulating antigens during invasive candidosis.

Two latex agglutination tests for the detection of Candida antigens, Pastorex Candida (Sanofi Diagnostics Pasteur, Marnes-la-Coquette, France) and Cand-Tec (Ramco Laboratories, Inc., Houston, Tex.), were applied to 79 serum samples from 19 patients who were retrospectively selected on the basis of mycological and clinical evidence of C. albicans infection and the availability of serial serum samples taken near the date of a positive culture. The specificity in 60 control individuals was 100% for Pastorex and 98.3% for Cand-Tec. The tests scored positive for 10 (52.6%) and 9 (47.4%) patients, respectively. Pastorex detected antigen in only 3 of 12 patients (25%) with positive antibody detection tests, but was positive for all 7 patients (100%) who produced no or a low antibody response, suggesting that the test performs better in the absence of antibodies. However, the sensitivity of Pastorex also increased with the number of samples available per patient, which was lower for high-antibody-responder patients (2.8 versus 5.7). If the patients who provided only one or two serum samples were eliminated, the sensitivity of Pastorex rose to 76.9%. For the Cand-Tec, the sensitivity was not related to the presence of antibodies, nor was it related to the number of samples per patient. The observed antigenemia was transient with both Pastorex and Cand-Tec. Only 12.5% of the positive reactions occurred on the same serum sample, confirming that the two tests react with different antigens. A positive antigen test preceded other diagnostic indications for 6 of 10 Pastorex-positive patients and 5 of 9 Cand-Tec-positive patients.

Adult↗
PubMed1992

Triptosine, an L-5-hydroxytryptophan derivative, reduces alcohol consumption in alcohol-preferring rats.

Triptosine is a new L-5-hydroxytryptophan derivative whose effect has been studied in the Long-Evans alcohol-preferring rat. At an oral dose of 100 mg/kg once daily, triptosine reduced alcohol consumption by 42% in the second week of treatment and increased that of water by 80%. The results suggest that this precursor of serotonin might play an important role in diminishing preference for alcohol and reaccustoming the animal to water, without exerting an anorexic effect.

5-Hydroxytryptophan↗
PubMed1991

1H-NMR spectroscopy of manno-oligosaccharides of the beta-1,2-linked series released from the phosphopeptidomannan of Candida albicans VW-32 (serotype A).

Manno-oligosaccharides (DP 2 to greater than 15) were released by mild acid hydrolysis from the phosphopeptidomannan of a Candida albicans strain of A serotype (VW-32). Manno-oligosaccharides ranging from biose to heptaose were obtained in appreciable amount. Structural investigation of these oligosaccharides showed them to be of the beta-1,2-linked series. The occurrence of such compounds has already been reported in other strains of Candida albicans. We here report the assignment of the structural reporter groups of each of them, and general rules applicable for the 1H-NMR spectrum analysis of linear manno-oligosaccharide of general structure: Man(beta 1-2) [Man(beta 1-2)]nMan

Candida albicans↗
PubMed1991

Imaging of systemic Candida albicans infections with a radioiodinated monoclonal antibody: experimental study in the guinea pig.

Guinea pigs intravenously infected with Candida albicans were scanned to evaluate the use of radioiodinated monoclonal antibodies (MAb) to fungal antigens for detecting tissue infection sites. A total of 18 infected and 8 uninfected animals were used. MAb and F(ab')2 fragments directed against cell wall glycoproteins of C. albicans were labeled with 131I. Another MAb directed against a Schistosoma mansoni glycoprotein was labeled with 125I and used as a nonspecific control. Radiolabeled MAbs were injected at a dose of 12.5 micrograms (500 kBq) per animal. Images were acquired 24 h later. Animals were then killed and the dissected organs were separately gamma-counted. The number of C. albicans colony forming units (cfu) per gram was determined in each organ. A clear relationship was found between the anatomic distributions of C. albicans and 131I. The biodistribution of 131I radioactivity associated with anti-Candida MAb was greater in infected animals than in healthy animals and increased with the number of cfu per g in each organ. The distribution was highly specific in animals with Candida endophthalmitis, a pathognomic feature of organ involvement during hematogenous dissemination. In contrast, the distribution of 125I radioactivity associated with the nonspecific MAb was similar in healthy and infected animals. In infected animals, it was totally independent of the intensity of fungal infection.

Animals↗
PubMed1990

Evaluation of a gold-silver staining method for detection and identification of Candida species by light microscopy.

A gold-silver staining procedure was evaluated for detection of Candida species of medical importance. Probes were prepared by coupling lectins or antibodies (polyclonal and monoclonal) directly or indirectly to colloidal gold particles. Structures reacting to these probes were specifically revealed by light microscopy in cells present in infected kidney tissue sections or in isolated yeast cells on glass slides. Definition, contrast and sensitivity were of a high order. Preliminary data showed that it was possible, using discriminating dilutions, to identify cells from different species of the genus Candida, grown in vitro, according to their ability to stain with polyclonal monospecific antisera. The advantages of gold-silver staining compared with other staining procedures currently used in routine mycological laboratories are its sensitivity, good definition, ease and rapidity, and long conservation of reaction. It is suggested that the procedure has applications for research and identification of yeasts in clinical samples.

Candida↗
PubMed1990

[Candidiasis: molecular basis of parasitic adaptation of opportunistic pathogenic protists].

Candida albicans is a versatile organism living as a commensal of the gastro-intestinal tract and having the ability to invade host tissues and to initiate serious diseases under the appropriate environmental conditions. The molecular basis for adherence, invasion, interactions with specific and non-specific immune factors have been studied in parallel to structural characteristics of the yeast. The main parasitologic features are closely linked to phenotypic variations. In this respect, mannoproteins are strongly involved in the cell wall variations. The study of the oligomannosidic repertoire represents one of the essential steps for the understanding of host-parasite relationships.

Candida albicans↗
PubMed1990

Expression of an epitope by surface glycoproteins of Candida albicans. Variability among species, strains and yeast cells of the genus Candida.

Expression of an antigenic epitope reactive with an IgM monoclonal antibody was studied in 253 Candida isolates by direct agglutination. Isolates of Candida albicans reacted significantly more often with the antibody than did isolates of other species. The agglutination scores for C. albicans isolates from sources associated with possible deep-seated Candida infection were significantly higher than for those from other sources. However, there was considerable overlap of scores between these two groups so that the functional significance of the association is uncertain. There were no associations between agglutination score and C. albicans biotype: multiple isolates from individual patients gave similar agglutination scores. Expression of the epitope within colonies of cloned strains was studied by autoradiography of colony blots on nitrocellulose and by immunoperoxidase staining of colonies in situ. It was found that the epitope was expressed variably by portions of colonies of both agglutination-positive and agglutination-negative strains. Indirect immunofluorescence revealed that expression of the epitope at the surface of C. albicans germ tubes and their associated buds was variable from cell to cell. It was not directly related to morphology or stage of growth of the cells.

Agglutination Tests↗
PubMed1990

Immunoreactivity of neoglycolipids constructed from oligomannosidic residues of the Candida albicans cell wall.

To establish a model to study the immunoreactivity of oligosaccharidic structures from the Candida albicans cell wall, we attempted to construct neoglycolipids with these residues by using oligomannosides released after mild acid hydrolysis of the phosphopeptidomannans isolated from yeast forms. From a mixture of manno-oligosaccharides ranging from mannobiose to mannononaose, the structure of a quantitatively major component (mannotriose) was determined to be Man (beta 1-2) Man (beta 1-2) Man alpha by 1H nuclear magnetic resonance analysis. After coupling of the pool of oligosaccharides to a lipid (4-hexadecylaniline), the synthesized molecules were injected into mice and rats. Antibody responses were detected on enzyme-linked immunosorbent assay plates coated with either phosphopeptidomannans or neoglycolipids. The hybrid molecules exhibited both immunogenicity and antigenicity. The kinetics of antibody responses as well as immunofluorescence patterns observed on whole C. albicans cells strongly mimicked results from the immunization of animals with natural antigens. Construction of neoglycolipids could therefore provide an interesting approach to the study of specific oligosaccharides of C. albicans and their recognition by the host immune system.

Animals↗