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Betschart, Bruno

Nom
Betschart, Bruno
Affiliation principale
Fonction
Professeur.e émérite
Email
bruno.betschart@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/302

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  • Publication
    Métadonnées seulement
    Trypanosoma-Brucei-Brucei and High-density-lipoproteins - old and new thoughts on the identity and mechanism of the trypanocidal factor in human serum
    (1995)
    Lorenz, Patrick
    ;
    Betschart, Bruno 
    ;
    Owen, James S
    Nature has Provided humans with a surprising means of protection against the African trypanosome, Trypanosoma brucei brucei. There is consensus, in that this singular trypanocidal factor is serum high-density lipoproteins (HDL), which the trypanosomes engulf through a physiological, receptor-mediated pathway for delivery to acidic intracellular vesicles. There is also controversy, however, in that the active particles and their essential cytotoxic elements are disputed, in part reflecting the ill-defined mechanism by which the parasites are finally killed. Here Patrick Lorenz, Bruno Betschart and jim Owen discuss the possibilities for resolving these discrepancies and speculate on the prospects of exploiting this unexpected Property of human HDL for Protecting livestock.
  • Publication
    Métadonnées seulement
    Heterogeneity in the properties of the trypanolytic factor in normal human serum
    (1994)
    Lorenz, Patrick
    ;
    James, Richard W
    ;
    Owen, James S
    ;
    Betschart, Bruno 
    Although it seems clear that the trypanolytic factor in human serum capable of killing Trypanosoma brucei brucei is high density lipoprotein (HDL), it nevertheless remains controversial as to whether the trypanolytic properties of HDL are confined to a specific subclass or whether all particles have activity. In the present study, we have compared the lytic activities of serum fractions from six normal individuals prepared by gradient ultracentrifugation and also, to avoid ultracentrifugally-induced loss of HDL apolipoproteins, by gel filtration using fast protein liquid chromatography (FPLC). All sera displayed trypanolytic activity in fractions corresponding to the general density (rho = 1.06-1.20 g ml(-1)) and size (59-440 kDa) limits conventionally used to describe bulk human HDL, the particles between rho = 1.18-1.20 g ml(-1) and between 214-440 kDa being particularly lytic. But some sera additionally contained fractions with powerful activity outside these density (rho > 1.24 g ml(-1)) and size (> 1000 kDa) ranges. Nevertheless, such fractions were considered to contain material with HDL characteristics; apolipoprotein A-I, the major protein of HDL, was always present and the lytic activity of the sera could be completely neutralized by absorption with HDL antiserum. We conclude that all of the trypanolytic activity in human sera is associated with HDL particles and that it is a property of several HDL subpopulations with very different density and size characteristics. Presumably the well-recognized wide variation in trypanocidal activity of normal human sera reflects differences in the quantities of these HDL subpopulations rather than in the total amount of a single, uniquely lytic particle.