58 research outputs found

    Two-colour generation in a chirped seeded Free-Electron Laser

    Full text link
    We present the experimental demonstration of a method for generating two spectrally and temporally separated pulses by an externally seeded, single-pass free-electron laser operating in the extreme-ultraviolet spectral range. Our results, collected on the FERMI@Elettra facility and confirmed by numerical simulations, demonstrate the possibility of controlling both the spectral and temporal features of the generated pulses. A free-electron laser operated in this mode becomes a suitable light source for jitter-free, two-colour pump-probe experiments

    Prion Protein Accumulation In Lipid Rafts of Mouse Aging Brain

    Get PDF
    The cellular form of the prion protein (PrP(C)) is a normal constituent of neuronal cell membranes. The protein misfolding causes rare neurodegenerative disorders known as transmissible spongiform encephalopathies or prion diseases. These maladies can be sporadic, genetic or infectious. Sporadic prion diseases are the most common form mainly affecting aging people. In this work, we investigate the biochemical environment in which sporadic prion diseases may develop, focusing our attention on the cell membrane of neurons in the aging brain. It is well established that with aging the ratio between the most abundant lipid components of rafts undergoes a major change: while cholesterol decreases, sphingomyelin content rises. Our results indicate that the aging process modifies the compartmentalization of PrP(C). In old mice, this change favors PrP(C) accumulation in detergent-resistant membranes, particularly in hippocampi. To confirm the relationship between lipid content changes and PrP(C) translocation into detergent-resistant membranes (DRMs), we looked at PrP(C) compartmentalization in hippocampi from acid sphingomyelinase (ASM) knockout (KO) mice and synaptosomes enriched in sphingomyelin. In the presence of high sphingomyelin content, we observed a significant increase of PrP(C) in DRMS. This process is not due to higher levels of total protein and it could, in turn, favor the onset of sporadic prion diseases during aging as it increases the PrP intermolecular contacts into lipid rafts. We observed that lowering sphingomyelin in scrapie-infected cells by using fumonisin B1 led to a 50% decrease in protease-resistant PrP formation. This may suggest an involvement of PrP lipid environment in prion formation and consequently it may play a role in the onset or development of sporadic forms of prion diseases

    [Premature membrane rupture. Comparison of diagnostic tests].

    No full text
    BACKGROUND: Objective of this study was to evaluate the accuracy of the vaginal pH-test, the Fern-test, the research of foetal cells and of foetal fibronectin in vaginal discharge, which are used to diagnose premature rupture of membranes. METHODS: To this aim 40 pregnant patients between 24th and 37th weeks gestation have been examined, considered at risk for sub-clinic loss of aminiotic fluid: 23 were affected by preterm labour and 17 by suspected rupture of membranes. RESULTS: Subsequently amniotic sac was confirmed to be ripped in 10 cases (25%): 2 (8.7%) in the 23 patients with preterm labour, and 8 (47%) in the 17 patients with suspected PROM. Sensibility, specificity and accuracy were respectively: 70, 97 and 90% for pH-test; 70, 100 and 93% for Fern-test; 50, 93 and 82% for foetal cells; 100, 90 and 93% for fibronectin test. CONCLUSIONS: In personal experience fibronectin test appeared to be the most sensible and accurate marker. Fern-test was the most specific, while the research of foetal cells appeared to be the least reliable
    • …
    corecore