Biomedical subjects
Publications and source records attributed to J M Senet.
We have demonstrated resistant forms of Trichomonas vaginalis studied their morphology and induced transformation into vegetative forms. This work has led to an hypothesis concerning the parasite cycle which may throw light on the problems of transmission and resistance to therapeutic agents.
Purification procedures of Toxoplasma gondii suspensions are described. These methods were designed for the elimination of leucocytes or TG 180 cells. We have been using either gradient centrifugation in Ficoll or gel filtration. In the first case, only leucocytes are eliminated (95% of the initial content). On the other hand, gel filtration allowed the elimination of TG 180 cells. The yield (67% to 98%) depends on the chosen gel (Ultrogel AcA 202 or Sephadex G25 fine), and on the amount of TG 180 cells present before filtration.
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2640 sera were titered simultaneously with IHA and IFAT. The results obtained show a good correlation between the two technics used. The IHA test seems particularly useful in IgM detection and, according to the mode of operation, is able to detect lower titers of anti-toxoplasma antibodies than in the case of IFAT.
Three different sorts of antigen are prepared ultrasonically: a soluble endogenous antigen, an insoluble particular antigen and a total mixed antigen. Formolinized red blood cells are sensibilized with glutaraldehyde. The authors study the sensitivity of the suspensions as a function of the different modes of antigen preparation. The results are compared with those obtained by immunofluorescence. The authors show the usefulness of total ultrasonic antigen which provides suspensions of great sensitivity easily and economically prepared.
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Several isolates of dermatophytes covering 13 different species were studied for their haemagglutination activity with erythrocytes of different origins (human, bovine, sheep, mouse and rabbit). The best results were obtained with rabbit erythrocytes. The specific haemagglutination activity of the fungal soluble extracts seemed to be closely related to the ecology of the fungi. Among the different carbohydrate (ose, polyol, osamine) and glycoprotein solutions used in the inhibition experiments, only N-acetyl-neuraminic acid and a sialoglycoprotein, the bovine submaxillary mucin (mucin type 1), showed an inhibiting activity, demonstrating the lectin nature of the haemagglutinins and the importance of sialic acids in the recognition process. Reduction of haemagglutination activity by pretreatment of rabbit erythrocytes with trypsin or neuraminidase solutions further supports this view.
In vitro fixation of human fibrinogen to different morphological stages of Candida albicans was examined immunocytochemically. When detected by fibrinogen latex microspheres or gold particles by scanning electron microscopy, fibrinogen-binding sites were found on the surface of germ tubes and mycelium, but not on blastospores. With transmission electron microscopy, fibrinogen-binding sites appeared associated with the flocculent surface layer, and increased during growth of germ tubes. Prefixation of C. albicans with formaldehyde decreased binding of fibrinogen, and pretreatment with mercaptoethanol and pronase abolished it. On thin sections of low temperature "Lowicryl K4M" -embedded organisms, gold particles were arranged in the form of clusters which extended from the surface through the cell wall. In contrast, the inner cell wall layers were weakly labelled. Labelling was also detected in the cytoplasm of germ tube, suggesting that fibrinogen receptors were synthesized during germ tube formation. In view of the importance of filamentous forms in host tissue adherence and colonization, the role of fibrinogen as a ligand for binding of C. albicans to epithelial cells was postulated.
The authors describe a method for isolation of Toxoplasma gondii antigenic membrane components. Technical work is described into four points: 1) specific labelling of membrane proteins was realised by DD125ISA; 2) methacrylate microspheres were bound to unbroken toxoplasma membranes by the mean of an indirect technic with antibody molecules (double sandwich); these microspheres were used to modify the membrane density; 3) toxoplasmas bound to microspheres were broken by sonication; 4) microspheres fixed to membrane components were isolated by isopycnic ultracentrifugation on continuous sucrose gradient.