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D Poulain

Publications and source records attributed to D Poulain.

At least 73 records · Page 4Linked to original sources
PubMed1989

Secretion of glycoproteins through the cell wall of Candida albicans.

A monoclonal antibody raised against the pathogenic phase of Candida albicans has been coupled to colloidal gold and used to detect the corresponding epitope in cell wall and culture medium of blastoconidia grown as germ tubes in vitro. Immunogold silver staining of Western blots of culture supernatants demonstrated release of the epitope into the culture medium. The stain revealed 3 well defined bands of 205,000, 66,000 and 30,000 Mr and a smear from the top of the gel to an Mr of 120,000. Immunoelectron microscopy of ultrathin frozen sections of the corresponding growth forms showed that epitope accumulated first in the periplasmic space, generally corresponding to plasmalemma invaginations within the cytoplasm. From these sites, it was possible to follow continuous lines of epitope distribution through the cell wall and antigenic extrusion at the cell surface. In tangential sections of intensely labeled walls, these preferential excretion ways appeared to be organized as a parallel network. Antigen emergence at the cell surface corresponded to patches of material which tended to coalesce in an easily dissociated layer, probably corresponding to the fuzzy coat. These experiments demonstrate, for the first time, preferential ways for cellular secretion through the yeast cell wall.

Antibodies, Monoclonal↗
PubMed1988

Electric and chemical fusions for the production of monoclonal antibodies reacting with the in-vivo growth phase of Candida albicans.

To obtain monoclonal antibodies (MAbs) directed preferentially against the pathogenic phase of Candida albicans, mice were immunised with germ tubes of C. albicans serotype A, strain VW.32, killed by exposure to ultraviolet (UV) irradiation. Fusions were performed either by the standard chemical procedure with polyethylene glycol, or by electric discharge following linkage of the myeloma and lymphocyte cells with a Concanavalin A-mannoprotein bridge. The preliminary characteristics of one MAb obtained from each of these fusions are described. An IgM antibody (3B7) obtained from the chemical fusion reacted with a polysaccharide antigen that was heterogeneously distributed on both in-vitro and in-vivo forms of C. albicans. This MAb agglutinated different strains of C. albicans irrespective of their serotype. An IgG1 antibody (3G6) that had been obtained from the electric fusion was found to react in vitro with a proteinaceous antigen located only on the germ tubes of strain VW.32. However, MAb 3G6 displayed strong reactivity against all growth forms of C. albicans in vivo and reactivity extended to other strains.

Agglutination Tests↗
PubMed1987

gamma-Aminobutyric acid as an inhibitory neurotransmitter in the rat supraoptic nucleus: intracellular recordings in the hypothalamic slice.

Intracellular recordings have been made from rat supraoptic neurones in the hypothalamic slice preparation. Application of gamma-aminobutyric acid (GABA) caused all neurones to hyperpolarise and this was accompanied by an increase in membrane conductance. GABA application examined on a variety of cells was found to have a potent influence on patterning of electrical activity, always consistent with an inhibitory action.

Acetylcholine↗
PubMed1987

[Detection of an antigen related to systemic Candida infection using a monoclonal antibody conjugated to colloidal gold].

Previously we showed it was possible to detect antigenemia associated with systemic candidiasis using an anti-C. albicans monoclonal antibody conjugated to colloidal gold. The technique being used, known as Immuno-Gold-Silver staining (IGSS), is applied to serum dots on cellulose nitrate. It is very simple in practice, the results of the reaction being visible with the naked eye. The diagnostic value of IGSS has been compared, on the one hand, with that of the anti-Candida antibody detection by co-counterimmunoelectrophoresis and indirect immunofluorescence, on the other hand with that of the antigen detection using the Cand-Tec commercial test. The specificity and sensitivity of these methods have been established in relation to sera of 79 subjects shared out into 4 groups: sound-subjects, patients having developed systemic candidiasis following surgery, leukemic patients apparently uninfected with Candida and leukemic patients suffering from systemic candidiasis. The IGSS which is slightly less specific than the Cand Tec makes it possible to diagnose a much greater number of infections. Selected bioclinical observations show that there exists complementarity between the detection tests of antibodies and those of antigens and that it is possible to attribute a prognosis value to antigenemia detected with the IGSS dot method.

Antibodies, Monoclonal↗
PubMed1987

[Evaluation of perfusion technics of the magnocellular nucleus of the hypothalamus in vitro and in vivo].

In suckled rats, OT necessary for the occurrence of the neurosecretory bursts on OT cells, is probably released inside the magnocellular nuclei. In order to demonstrate this in vivo release and to precise the mechanism involved, perifusions were realized in vivo on lactating rats and in vitro with isolated magnocellular nuclei. In vivo, the push-pull perifusion of a single supraoptic nucleus (SON) was realized simultaneously with the recording of the electrical activity of OT cells in the contralateral nucleus. This would allow to determine the possible relationships between the amount of OT released in the SON and the electrical activity of OT cells (bursting activation during suckling or continuous activation during an hyperosmotic stimulation). Results obtained showed 1) that OT was released in vivo inside the SON, 2) that this release was specifically increased during the milk ejection reflex and 3) that this increase was only detectable inside the SON. However, this technique did not permit to determine either the mechanism of OT release or the neuron elements (perikaryon, dendrites, axon collaterals) responsible for this release. That is for why, in vitro perifusions were undertaken with isolated magnocellular nuclei. The first stage was to determine the stimulus able to induce a reproducible increase of OT release. Among the chemical stimuli (neurotransmitters, K+) only K+ at a 56 mM concentration increased OT release by SON but this increase was small and non significant. Repetitive electrical stimulations with short pulses (0.2 to 5 msec) were ineffective even if the pulse intensity was raised up to 10 mA and the frequency up to 80 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Diagnosis of systemic candidiasis: development of co-counterimmunoelectrophoresis.

To improve the results of counterimmunoelectrophoresis for serological diagnosis of candidiasis, a new method was devised to characterize human sera precipitins: co-counterimmunoelectrophoresis. Cellulose acetate was chosen as the support in order to observe identity reactions between precipitin lines from serum systems run conjointly (thus, co-counterimmunoelectrophoresis). Different experimental antisera (anti-somatic and anti-cytoplasmic antigens and anti-whole fixed germ tube antisera) were tested for reactions of identity with sera from selected patients with systemic candidiasis caused by Candida albicans. The reaction of patient sera and anti-germ tube antiserum with a selected somatic antigen always resulted in an identity reaction as proven by the continuity of major precipitin lines. The precipitating system, named the co-specific precipitin line, involved polysaccharide antigens; it was not present in human control sera.

Adult↗
PubMed1986

Diagnosis of systemic candidiasis: application of co-counterimmunoelectrophoresis.

The accuracy of co-counterimmunoelectrophoresis was compared with mycological and clinical data for different groups of inpatients. The specificity and sensitivity of this method ranged from 100 to 69%. The co-specific precipitin line was observed during systemic infections caused by most opportunistic Candida species. The variations in the line in successive serum samples provided a simple means of serological surveillance. The test also detected seroconversion. The gradual disappearance of the line reflected a favourable prognosis, whereas its abrupt disappearance indicated unfavourable prognosis and correlated with the appearance of detectable circulating antigens.

Adult↗
PubMed1986

A monoclonal antibody to a cell wall component of Candida albicans.

A heterologous fusion between mouse myeloma cells and rat lymphocytes resulted in the isolation of a rat immunoglobulin M monoclonal antibody with both agglutinating and precipitating activity. Indirect immunofluorescence and direct agglutination tests showed that the corresponding antigen was present in the cell wall of the three Candida species considered to be the most pathogenic, C. albicans, C. tropicalis, and C. glabrata, and also in the cell wall of C. guilliermondii. The antigen appeared to be predominantly polysaccharide in nature. Precipitation by counterimmunoelectrophoresis suggested that the epitope is shared by at least two separate molecules with different electrophoretic mobilities. Presence of this epitope varied from strain to strain within a given species and may be related to the morphological stage in the cell cycle. Antigen was shown to be present in the cytoplasm, in the periplasmic space, and at the cell surface of C. albicans. Indirect immunofluorescence also suggested that antigen is excreted from the cell.

Agglutination↗
PubMed1986

[Application of a co-electrosyneresis reaction to the diagnosis and serological surveillance of candidiasis in a hospital milieu].

We have previously described a co-immunofiltration reaction which identifies a specific precipitating system (SPCS) in sera from patients presenting systemic candidiasis. The SPCS is characterized by coalescence with an experimental serum directed against the germinative tubes of Candida albicans. The present study concerns our experience of the use of co-immunofiltration in routine hospital practice. Complete observations involving clinical, mycological and serologic data were selected in order to illustrate various possible developmental trends for SPCS during candidiasis. The SPCS usually develops early infections due to the yeast species most frequently implicated in hospital pathologies; an increase in its intensity reflects a developing infection or the start of therapy. The SPCS disappears slowly and gradually when infectious development is favorable, but its sudden disappearance represents an unfavorable prognosis correlated with detection of circulating antigens. Circulating antigens are also seen in severe cases of candidiasis in which the SPCS is not present. Indeed there is a certain complementarity between these two observations.

Antibody Formation↗
PubMed1985

[Use of a method of lipid extraction from Candida albicans cell walls blastospores. Ultrastructural implications concerning their localization and parietal microfibril organization].

A chemical method for lipid extraction has been applied to Candida albicans blastospores previously to their examination by transmission electron microscopy. The results led to the concept of a superficial location of lipids bounded to the peptidopolysaccharidic matrix of the cell wall. This lipid extraction also allowed us to describe cell wall microfibrillar structures. Two types of microfibrills have been particularly identified: microfibrils of approximately 50 A in diameter, involved in a network of the cell wall intermediate layers and supposed to correspond to beta 1-3 glucans; fibrillar structures of 120 A in diameter, similar to chitin microfibrils, observed in the bud scar septum.

Candida albicans↗
PubMed1985

Chemical and antigenic alterations of Candida albicans cell walls related to the action of amphotericin B sub-inhibitory doses.

Sub-inhibitory doses of amphotericin B led to Candida albicans cell wall modifications which involved peptidomannans. The amount of this product was reduced by a third, the decrease being due to mannans whose absolute and relative values fell whereas the amount of amino-acids increased. Concomitantly, the treated cells exhibited a loss in their immunological reactivity.

Amino Acids↗
PubMed1985

Antigenic variability of Candida albicans.

The concepts of modern biology lead us to think that all structures are liable to continual changes. Ultrastructural and biochemical methods have been able to objectify such a dynamic in Candida albicans, an opportunistic yeast. A broad analysis of antigens is a reliable way to study the antigenic variations which concern this organism. Numerous information on somatic and metabolic antigens of C. albicans is available at the moment. Paradoxically, if one accepts studies dealing with dimorphism, very few works have shown antigenic variability of this species or investigated the mechanisms involved in such a variability. The few approaches done in this way tend to prove that it may be possible to link together the expression of particular antigens and the behavior of the yeast, particularly when it acts as a pathogen.

Animals↗
PubMed1984

Cytochemical and ultrastructural studies of Candida albicans. III. Evidence for modifications of the cell wall coat during adherence to human buccal epithelial cells.

Ultrastructural modifications of the cell wall coat of Candida albicans during adherence to host cells were investigated using various cytochemical techniques. Attachment of the fungus to buccal epithelial cells appeared to involve spatial rearrangement of their cell wall surface. In particular adhering yeast developed a fibrogranular surface layer visualized by the periodic acid--thiocarbohydrazide--silver proteinate technique (a polysaccharide detection technique); Concanavalin A binding sites detected on their cell wall coat were highly increased. Attachment of yeasts to epithelial cells appeared mediated by fibrillar structures or polysaccharidic granules distributed on the cell wall coat. But free extra-cell wall material containing mannoproteins released from the yeast surface suggested additional mechanisms.

Adhesiveness↗
PubMed1984

A means to assess nursing efficiency in the pig: the study of the milk ejection reflex.

We have recently devised a method for recording the intramammary pressure in conscious lactating sows. This technique allows for unambiguous detection of milk ejection, and permits correlation with hormone release and the behaviour of the sows and their piglets. Each milk ejection is characterized by an abrupt rise in intramammary pressure lasting 8-40 sec only. This is preceded 15-30 before by a rise in plasma concentrations of the hormone oxytocin. Milk ejections only occurred when the sow was nursing her litter, lying on her side and making her teats available. She usually grunted in a rhythmic manner, with a sharp increase in the frequency of grunts about 23 sec before milk ejection. Grunting ceased within 1 min thereafter. The whole litter had to be suckling to obtain a milk ejection, which occurred about 2-4 min after the onset of the initial phase of massage of the udders, and was coincident with a brief period of quiet suckling. Milk ejections occurred about every 45 min, i.e. only once per suckling period, eventhough the period could last over 15 min. They never occurred if the mother was not nursing, or if the piglets attempted to suckle too soon after a milk ejection. Out of 144 periods of suckling, over 20% of failures to eject milk were observed, in which case there was no oxytocin release in blood. Some "incomplete" sucklings happened with no apparent reasons, but their incidence was very high when the sow appeared to be disturbed.

Animals↗
PubMed1984

[Fungal infections: involved species and minimal inhibitory concentrations of common antifungal agents].

Fungal cultures of cutaneous or ungual origin (477 cultures), nasopharyngeal and urogenital origin (2,000 cultures), and blood, internal organs, surgical incisions, and catheters (300 cultures) were obtained in this study. Analysis of the data yielded the following information: Candida albicans and C. tropicalis, frequent causes of superficial or systemic mycoses, were very sensitive to flucytosine and amphotericin B in a liquid medium, but less sensitive to the imidazole derivatives; C. parapsilosis, a cause of superficial and systemic mycoses, was remarkably sensitive to all four antifungal agents tested; Torulopsis glabrata and C. krusei are of greatest concern in a hospital setting since systemic or visceral infections are minimally sensitive to antifungal agents; C. pseudotropicalis, C. guilliermondii, and C. zeylanoides are less pathogenic and sensitive to antifungal agents varies, depending on the strain. Specific measures are presented for management of fungal infections in a hospital setting. The role of antifungal susceptibility testing in everyday practice is also evaluated.

Amphotericin B↗