719 research outputs found

    Combined effect of plastic litter and increased atmospheric nitrogen deposition on vegetative propagules of dune plants: a further threat to coastal ecosystems

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    Large amounts of non-biodegradable plastics are currently deposited on beach-dune systems, and biodegradable plastics could enter these already declining habitats in coming years. Yet, the impacts of plastics on vegetative recruitment, a plant strategy playing a key role in dune stabilization, are unknown. Whether these pollutants interact with increased atmospheric nitrogen (N) deposition, a major global driver of plant biodiversity loss, in affecting plant communities of such nutrient-poor habitats, and how plant-plant interactions mediate their effects need to be explored. In a one-year field experiments, we examined individual and combined effects of plastic (non-biodegradable, biodegradable), N deposition (ambient, elevated) and biotic condition (no interaction, interaction with a conspecific or with a hetero-specific) on the colonization success and growth of vegetative propagules of dune plants. Thinopyrum junceum and Sporobolus pumilus were chosen as models because they co-occur along Mediterranean dunes and differ in ecological role (dune- vs. non dune-building) and photosynthetic pathway (C3 vs. C4). For both species, survival probability was reduced by non-biodegradable plastic and elevated N by up to 100%. Thinopyrum junceum survival was also reduced by S. pumilus presence. Elevated N and biodegradable plastic reduced T. junceum shoot biomass when grown alone and with a conspecific, respectively; these factors in combination mitigated their negative individual effects on root biomass. Biodegradable plastic increased S. pumilus shoot and root biomass, and in combination with elevated N caused a greater biomass investment in belowground (root plus rhizome) than aboveground organs. Non-biodegradable plastic may be a further threat to dune habitats by reducing plant colonization. Biodegradable plastic and increased N deposition could favour the generalist S. pumilus and hinder the dune-building T. junceum. These findings highlight the urgency of implementing measures for preventing plastic deposition on beaches and reducing N input

    In Search of Differential Inhibitors of Aldose Reductase

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    Aldose reductase, classified within the aldo-keto reductase family as AKR1B1, is an NADPH dependent enzyme that catalyzes the reduction of hydrophilic as well as hydrophobic aldehydes. AKR1B1 is the first enzyme of the so-called polyol pathway that allows the conversion of glucose into sorbitol, which in turn is oxidized to fructose by sorbitol dehydrogenase. The activation of the polyol pathway in hyperglycemic conditions is generally accepted as the event that is responsible for a series of long-term complications of diabetes such as retinopathy, cataract, nephropathy and neuropathy. The role of AKR1B1 in the onset of diabetic complications has made this enzyme the target for the development of molecules capable of inhibiting its activity. Virtually all synthesized compounds have so far failed as drugs for the treatment of diabetic complications. This failure may be partly due to the ability of AKR1B1 to reduce alkenals and alkanals, produced in oxidative stress conditions, thus acting as a detoxifying agent. In recent years we have proposed an alternative approach to the inhibition of AKR1B1, suggesting the possibility of a differential inhibition of the enzyme through molecules able to preferentially inhibit the reduction of either hydrophilic or hydrophobic substrates. The rationale and examples of this new generation of aldose reductase differential inhibitors (ARDIs) are presented

    Multimode photonic molecules for advanced force sensing

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    We propose a force sensor, with optical detection, based on a reconfigurable multicavity photonic molecule distributed over two parallel photonic crystal membranes. The system spectral behaviour is described with an analytical model based on coupled mode theory and validated by finite difference time domain simulations. The deformation of the upper photonic crystal membrane, due to a localized vertical force, is monitored by the relative spectral positions of the photonic molecule resonances. The proposed system can act both as force sensor, with pico-newton sensitivity, able to identify the position where the force is applied, and as torque sensor able to measure the torsion of the membrane along two perpendicular directions

    Supramolecular Assemblies in Silver Complexes: Phase Transitions and the Role of the Halogen Bond

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    Weak interactions (hydrogen bonds, halogen bonds, CH···πand Ï€-πstacking) can play a significant role in the formation of supramolecular assemblies with desired structural features. In this contribution, we report a systematic investigation on how a halogen bond (XB) can modulate the structural arrangement of silver supramolecular complexes. The complexes are composed of X-phenyl(bispyrazolyl)methane (X = Br, I) and I-alkynophenyl(bispyrazolyl)methane ligands functionalized in meta (L3Br, L3I) and para (L4Br, L4I, L4CCI) positions on a phenyl ring with the purpose of providing different directionalities of the X function with respect to the N,N coordination system. The obtained [Ag(L)2]+ moieties show remarkable geometric similarities, and the L4Br, L4I, and L4CCI ligands exhibit the most conserved types of supramolecular arrangement that are sustained by XB. The increased σ-hole in L4CCI with respect to L4I leads to an occurrence of short (and strong) XB interactions with the anions. [Ag(L4I)2]PF6 and [Ag(L4I)2]CF3SO3 are characterized by the presence of three different phases, and the single-crystal evolution from phase-1 (a honeycomb structure with large 1D cavities) to phase-3 (solventless) occurs by a stepwise decrease in the crystallization solvent content, which promotes an increase in XB interactions in the lattice. The present paper aims to provide useful tools for the selection of appropriate components for the use of coordination compounds to build supramolecular systems based on the halogen bond

    Experimental study of the delayed threshold phenomenon in a semiconductor laser

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    An experimental study of the delayed threshold phenomenon in a Vertical Extended Cavity Semiconductor Emitting Laser is carried out. Under modulation of the pump power, the laser intensity exhibits a hysteresis behavior in the vicinity of the threshold. The temporal width of this hysteresis is measured as a function of the modulation frequency, and is proved to follow the predicted scaling law. A model based on the rate equations is derived and used to analyze the experimental observations. A frequency variation of the laser around the delayed threshold and induced by the phase-amplitude coupling is predicted and estimated

    Pathways of 4-hydroxy-2-nonenal detoxification in a human astrocytoma cell line

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    One of the consequences of the increased level of oxidative stress that often characterizes the cancer cell environment is the abnormal generation of lipid peroxidation products, above all 4-hydroxynonenal. The contribution of this aldehyde to the pathogenesis of several diseases is well known. In this study, we characterized the ADF astrocytoma cell line both in terms of its pattern of enzymatic activities devoted to 4-hydroxynonenal removal and its resistance to oxidative stress induced by exposure to hydrogen peroxide. A comparison with lens cell lines, which, due to the ocular function, are normally exposed to oxidative conditions is reported. Our results show that, overall, ADF cells counteract oxidative stress conditions better than normal cells, thus confirming the redox adaptation demonstrated for several cancer cells. In addition, the markedly high level of NADP+-dependent dehydrogenase activity acting on the glutahionyl-hydroxynonanal adduct detected in ADF cells may promote, at the same time, the detoxification and recovery of cell-reducing power in these cells

    Dual targeting of ptp1b and aldose reductase with marine drug phosphoeleganin: A promising strategy for treatment of type 2 diabetes

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    An in-depth study on the inhibitory mechanism on protein tyrosine phosphatase 1B (PTP1B) and aldose reductase (AR) enzymes, including analysis of the insulin signalling pathway, of phosphoeleganin, a marine-derived phosphorylated polyketide, was achieved. Phosphoeleganin was demonstrated to inhibit both enzymes, acting respectively as a pure non-competitive inhibitor of PTP1B and a mixed-type inhibitor of AR. In addition, in silico docking analyses to evaluate the interaction mode of phosphoeleganin with both enzymes were performed. Interestingly, this study showed that phosphoeleganin is the first example of a dual inhibitor polyketide extracted from a marine invertebrate, and it could be used as a versatile scaffold structure for the synthesis of new designed multiple ligands

    Clinical‐epidemiological aspects of the Monkeypox 2022 epidemic: a multicenter study by the Italian SIDeMaST Group of Sexually Transmitted, Infectious and Tropical Diseases

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    Dear Editor,In spring 2022, an increase of monkeypox (mpox) cases was reported in Europe. Mpox is a zoonotic virus of the Poxviridae family, is endemic in the Congo Basin and just few cases outside Africa were reported before 2022. Its cutaneous presentation is similar to smallpox, usually preceded by a prodromal phase of fever, lymphadenopathy, headache and asthenia. Infection can occur through various means, including skin-to-skin contact, respiratory droplets or contact with fomites. The new outbreak is unique due to the increased human-to-human transmission, without an animal reservoir, particularly among men who have sex with men (MSM). As of February 13, 2023, 85.860 confirmed cases have been reported in 110 countries

    Rufinamide in refractory childhood epileptic encephalopathies other than Lennox-Gastaut syndrome.

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    Background: To report on the first multicenter Italian experience with rufinamide as adjunctive drug in children, adolescents and young adults with refractory childhoodonset epileptic encephalopathies other than Lennox–Gastaut syndrome. Methods: Thirty-eight patients (19 males, 19 females), aged between 4 and 34 (mean 13.7 ± 8.3, median 12.5), all affected by different types of childhood-onset refractory epileptic encephalopathies other than Lennox–Gastaut syndrome, were treated with rufinamide as adjunctive drug for a mean period of 11.4 months (range 3–26 months). Results: Fifteen of 38 patients (39.5%) had a ‡50% seizure reduction in countable seizures. Complete seizure freedom was achieved in one of these patients (2.6%). Three patients (7.9%) had a 25–49% seizure reduction, whilst seizure frequency remained unchanged in 15 (39.5%) and increased in five patients (13.1%). Eleven patients (28.9%) reported adverse side effects. Vomiting was reported in five patients (13.1%); drowsiness, decreased appetite and irritability with migraine manifested in other four patients. They were transient and mild in all cases. Conclusion: Rufinamide may be an effective and well-tolerated adjunctive drug for the treatment of refractory childhood-onset epileptic encephalopathies other than Lennox–Gastaut syndrome. Rufinamide was most effective in patients with dropattacks and (bi)frontal spike–wave discharges. Introduction Rufinamide is a structurally triazole-derivative (1-[2,6- difluorophenyl)methyl]-1hydro-1,2,3-triazole-carboxamide) novel antiepileptic drug, structurally unrelated to the existing antiepileptic drugs, and approved by the Food and Drug Administration for the treatment of Lennox–Gastaut syndrome in patients aged 4 and over, and for the treatment of partial seizures in adults and adolescents. The proposed mechanism of action is the limitation of excessiv
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