Antonio Fogazzaro, Ellen Starbuck: carteggio (1885-1910): introduzione, edizione, note

Dottorato di ricerca in scienze letterarie, retorica e tecnica dell'interpretazione. 6. ciclo. A.a. 1991-94. Coordinatore Carmelo Salemme. Tutore Antonio DanieleConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Analogs of a natural peptaibol exert anticancer activity in both cisplatin-and doxorubicin-resistant cells and in multicellular tumor spheroids

Peptaibols, by disturbing the permeability of phospholipid membranes, can overcome anticancer drug resistance, but their natural hydrophobicity hampers their administration. By a green peptide synthesis protocol, we produced two water-soluble analogs of the peptaibol trichogin GA IV, termed K6-Lol and K6-NH2. To reduce production costs, we successfully explored the possibility of changing the naturally occurring 1,2-aminoalcohol leucinol to a C-terminal amide. Peptaibol activity was evaluated in ovarian cancer (OvCa) and Hodgkin lymphoma (HL) cell lines. Peptaibols exerted comparable cytotoxic effects in cancer cell lines that were sensitive\u2014and had acquired resistance\u2014to cisplatin and doxorubicin, as well as in the extrinsic-drug-resistant OvCa 3-dimensional spheroids. Peptaibols, rapidly taken up by tumor cells, deeply penetrated and killed OvCa-spheroids. They led to cell membrane permeabilization and phosphatidylserine exposure and were taken up faster by cancer cells than normal cells. They were resistant to proteolysis and maintained a stable helical structure in the presence of cancer cells. In conclusion, these promising results strongly point out the need for further preclinical evaluation of our peptaibols as new anticancer agents

Different mechanisms of inhibition of nerve terminals by botulinum and snake presynaptic neurotoxins

The different mode of action on peripheral nerve terminals of the botulinum neurotoxins and of the snake presynaptic phospholipase A2 neurotoxins is reviewed here. These two groups of toxins are highly toxic because they are neurospecific and at the same time are enzymes that can modify many substrate molecules before being inactivated. The similarity of symptoms they cause in humans derives from the fact that both botulinum neurotoxins (seven serotypes named A-G) and snake presynaptic PLA2 neurotoxins block the nerve terminals and that peripheral cholinergic terminals are major targets. Given this general similarity of targets and clinical symptoms, the specific molecular and cellular mechanisms at the basis of their action are very different. This difference appears evident from the beginning of intoxication, i.e. neurotoxins binding to peripheral nerve terminals and proceeds with the different site of actions and molecular targets

Botulinum Neurotoxin Type A is Internalized and Translocated from Small Synaptic Vesicles at the Neuromuscular Junction.

International audienceBotulinum neurotoxin type A (BoNT/A) is the most frequent cause of human botulism and, at the same time, is largely used in human therapy. Some evidence indicates that it enters inside nerve terminals via endocytosis of synaptic vesicles, though this has not been directly proven. The metalloprotease L chain of the neurotoxin then reaches the cytosol in a process driven by low pH, but the acidic compartment wherefrom it translocates has not been identified. Using immunoelectron microscope, we show that BoNT/A does indeed enter inside synaptic vesicles and that each vesicle contains either one or two toxin molecules. This finding indicates that it is the BoNT/A protein receptor synaptic vesicle protein 2, and not its polysialoganglioside receptor that determines the number of toxin molecules taken up by a single vesicle. In addition, by rapid quenching the vesicle trans-membrane pH gradient, we show that the neurotoxin translocation into the cytosol is a fast process. Taken together, these results strongly indicate that translocation of BoNT/A takes place from synaptic vesicles, and not from endosomal compartments, and that the translocation machinery is operated by no more than two neurotoxin molecules

Neuromuscular paralysis and recovery in mice injectedwith botulinum neurotoxins A and C

Botulinum neurotoxin type A (BoNT/A) is commonly used in human therapy. This treatment may induce immunoresistance and preliminary evaluation of other botulinum neurotoxin serotypes suggested botulinum neurotoxin type C (BoNT/C) to be a good alternative to BoNT/A. Here, we have further characterized the biological activities of BoNT/C using a variety of experimental approaches. Muscle paralysis and time of recovery of mouse hind limb injected with BoNT/A or BoNT/C were assayed with the Digit Abduction Scoring assay. The extent and duration of paralysis were similar with the two toxin serotypes. Extensor digitorum longus or tibialis anterior muscles were dissected at times of complete paralysis and of complete recovery. Muscle weight and force were significantly reduced in mice injected with BoNT/A and BoNT/C, and some atrophy persisted for a long time. In BoNT/C-treated junctions, nerve terminal sprouting was prominent, indicating that the capacity to extend the field of innervation is not hampered by BoNT/C. BoNT/C induced a marked decrease in the frequency of miniature endplate potentials and in the amplitude of endplate potentials. 3,4-diaminopyridine reversed the effect of BoNT/C by increasing the amplitude of synchronized endplate potentials. The present study shows an extensive similarity in the biological activities of BoNT/A and BoNT/C, further supporting the suggestion that BoNT/C is a valid alternative to BoNT/A

Peptide analogs of a Trichoderma peptaibol effectively control downy mildew in leaf disc assay and vineyard

Grapevine (Vitis vinifera) is one of the main crops worldwide. Plasmopara viticola, the causal agent of downy mildew, causes enormous economic damage in terms of yield, quality and productivity to this crop. Although the disease control is largely based on the use of synthetic fungicides, the European Union (UE) policies promote the reduction of the reliance on synthetic plant protection products (PPPs) and the implementation of integrated approaches to crop protection. Biocontrol agents (BCA) constitute a great resource for the development of biopesticides. The fungal genus Trichoderma includes different species commonly used as BCAs against several crop pathogens and among their antifungal strategies, there are secondary metabolites such as peptaibols. The promise of peptaibols as agrochemicals is, however, hampered by their poor water solubility, preventing an efficient delivery for practical use in crop protection. Some water-soluble trichogin analogs with Gly to Lys substitutions were synthesized and analyzed for their antimicrobial activity against P. viticola. Among the peptides that proved effective in inhibiting the oomycete sporulation on leaf discs assay, the peptide 4r was selected for a two-year field trial experiment. In comparison with the untreated control, the protection level was comparable to that obtained with a cupric fungicide. The peptide did not show any phytotoxic effect and reduced downy mildew incidence and severity on leaves and bunches. Since it was demonstrated active also against the fungal pathogen Botrytis cinerea, the peptide 4r may be a candidate broad-spectrum fungicide whose biological properties deserve further investigations

Vacuolation induced by VacA toxin of Helicobacter pylori requires the intracellular accumulation of membrane permeant bases, Cl- and water

The protein vacuolating toxin A (VacA) of Helicobacter pylori converts late endosomes into large vacuoles in the presence of permeant bases. Here it is shown that this phenomenon corresponds to an accumulation of permeant bases and Cl(-) in HeLa cells and requires the presence of extracellular Cl(-). The net influx of Cl(-) is due to electroneutral, Na(+), K(+), 2Cl(-) cotransporter-mediated transport. Cell vacuolation leads to cell volume increase, consistent with water flux into the cell, while hyper-osmotic media decreased vacuole formation. These data represent the first evidence that VacA-treated cells undergo an osmotic unbalance, reinforcing the hypothesis that the VacA chloride channel is responsible for cell vacuolation