1,721,099 research outputs found
Conductometric properties of human erythrocyte membranes: Dependence on haematocrit and alkali metal ions of the suspending medium
No full textThe electrical properties of the cytoplasmatic membrane of human erythrocyte cells have been evaluated by means of dielectric spectroscopy measurements in the radiowave frequency range, using the so-called ''suspension method''. Measurements have been carried out at different volume fractions of the corpuscular phase (the cell haematocrit) in order to investigate the influence of the cell-cell interactions on the electrical parameters (the membrane permittivity epsilon and the membrane conductivity sigma) of the cell membrane and a set of new values are proposed. Moreover, the influence of different alkali metal ions (Na+, K+, Cs+, Li+) on the ion permeation properties of the membrane are investigated and the structural alterations in the membrane organized briefly discussed
Association between GM3 and CD4-lck complex in human peripheral blood lymphocytes
No full textThe aim of this study was to further elucidate our previous observation on molecular interaction of GM3, CD4 and p56(lck) in microdomains of human peripheral blood lymphocytes (PBL). We analyzed GM3 distribution by immunoelectron microscopy and the association between GM3 and CD4-p56(lck) complex by scanning confocal microscopy and co-immunoprecipitation experiments. Scanning confocal microscopy analysis showed an uneven signal distribution of GM3 molecules over the surface of human lymphocytes. Nearly complete colocalization areas indicated that CD4 molecules were distributed in GMS-enriched plasma membrane domains. Co-immunoprecipitation experiments revealed that CD4 and p56(lck) were immunoprecipitated by IgG anti-GM3, demonstrating that GM3 tightly binds to the CD4-p56(lck) complex in human PBL. In order to verify whether GM3 association with CD4 molecules may depend on the presence of p56(lck), we analyzed this association in U937, a CD4 + and p56(lck) negative cell line, The immunoprecipitation with anti-GM3 revealed the presence of a 58 kDa band immunostained with anti-CD4 Ab, suggesting that the GM3-CD4 interaction does not require its association with p56(lck). These findings support the view that GM3 enriched-domains may represent a functional multimolecular complex involved in signal transduction and cell activation
Prosaposin-derived peptides enhanced sprouting of sensory neurons in vitro and induced sprouting at motor endplates in vivo
No full textProsaposin exhibits neurotrophic factor properties that are localized to a 12-amino acid sequence located in the amino terminal portion of the saposin C domain. Prosaptides are peptides derived from the neurotrophic portion of prosaposin; these have been previously reported to be bioactive in neuroblastoma cell lines in vitro. We report that prosaptides were also bioactive in explants of adult primary sensory neurons by dose-dependently increasing both the number (3- to 4-fold) and elongation of these neurites by 50%. Local injection of prosaptides into the gluteus muscle of adult mice also induced sprouting at the motor endplate. Our results indicate that prosaptides are potent neuritogenic factors for both sensory and motor neurons of adult peripheral nerve
Phospholipids, Beta-2Glycoprotein I, Prothrombin, Protein S and Protein C as a target of an “independent” immune response.
No full textInfluence of GM3 and GD3 glycolipids on the conductometric properties of a model membrane system.
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