10 research outputs found

    Effect of synthetic route on sintering behaviour, phase purity and conductivity of Sr- and Mg-doped LaGaO3 perovskites

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    La1-xSrxGa1-yMgyO3-d (LSGM) powders containing different amounts of Sr2+ and Mg2+ were prepared from precursors synthesised by either Pechini or citrate sol-gel method and by subsequent calcination at 1400 °C. Some powders were also submitted to further 10 h firing at 1500 °C. All as-calcined powders contained small amounts of Sr- and Ga-containing phases (namely SrLaGa3O7 and SrLaGaO4), as detected by X-Ray Diffraction (XRD). The relative amounts of these phases depended on x and y, i.e. the dopants’ levels. Nevertheless, powders prepared by the citrate method exhibited systematically higher phase purity than those obtained by the Pechini process. Calcined powders were then sintered at 1500 °C (10 h) in air and the degree of sintering was assessed by scanning electron microscopy (SEM). Phase composition of sintered pellets was different from that of powders. In fact, sintered pellets showed the presence of MgO, as detected by SEM, and of lesser amounts of SrLaGa3O7. Both these phases were less abundant in materials sintered using powders prepared by citrate method, thus suggesting that Pechini method does not represent the best wet chemical process for manufacturing. The conductivity of sintered pellets was measured by impedance spectroscopy in the 600–800 °C interval. Conductivity values of LSGM materials were affected by secondary phase segregation and, therefore, depended on both composition and sol-gel method synthetic route

    Are cytochrome P4502D6 and apolipoprotein E genotypes associated with long-term cognitive and functional changes in patients treated with donepezil?

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    We investigated the associations of the single-nucleotide polymorphism rs1080985 of cytochrome P4502D6 (CYP2D6) and the apolipoprotein E (APOE) genotypes with cognitive and functional changes in patients treated with donepezil. Sixty-five outpatients with Alzheimer's disease or mixed dementia being treated with donepezil were assessed at baseline and over 27 months. Changes in cognitive status, assessed with the Mini-Mental State Examination, and in functional status, assessed by the Activities of Daily Living Scale and the Instrumental Activities of Daily Living Scale, were evaluated as a function of CYP2D6 and APOE genotypes by using linear mixed models. Multiplicative interactions between the CYP2D6 and APOE genotypes and time were investigated. Individuals with the mutated CYP2D6 exhibited a slower decline in total Mini-Mental State Examination scores, orientation, registration, and functional status than those with the wild type. A significant interaction between CYP2D6, APOE, and time was found for changes in the Activities of Daily Living Scale; among the \u3b54 carriers, those with the mutated CYP2D6 exhibited a slower decline on the Activities of Daily Living Scale than those with the wild type. The CYP2D6 and APOE genotypes may modulate the effectiveness of donepezil on cognitive and functional status

    A new foodweb based on microbes in calcitic caves. The Cansiliella (Beetles) case in Northern Italy

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    The troglobitic beetle, Cansiliella servadeii (Leptodirini), has specialized mouthparts modified for browsing and feeding under percolating water on moonmilk, a speleothem formation in Grotta della Foos, Italy. Results from analyses of stable isotopes of carbon and nitrogen suggest that acquires and assimilates dissolved allochthonous organic carbon, inorganic nitrogen, and possibly phosphorus and other nutrients from the microbial fauna associated with moonmilk

    Donepezil plasma concentrations, CYP2D6 and CYP3A4 phenotypes, and cognitive outcome in Alzheimer\u2019s disease

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    The purpose of the study is to evaluate whether donepezil (D) plasma concentrations and activity of CYP2D6 and CYP3A4 are associated with the therapeutic response of patients with mild to moderate Alzheimer's disease (AD). This study comprised 54 patients affected by probable AD in therapy with D 10 mg/daily for at least 3 months. Plasma concentrations of D and its three main metabolites (6DD, 5DD, DNox) were assayed with a novel high performance liquid chromatography (HPLC) technique. Cognitive progression was assessed at baseline and at 9 months of follow-up with the mini mental state examination (MMSE). The activities of the two cytochromes involved in D metabolism-CYP2D6 and CYP3A4-were evaluated according to their metabolic ratios in plasma or urine, after test doses of probe drugs (dextromethorphan and omeprazole). A significant correlation was found between plasma levels of D and variations in MMSE scores after 9 months of therapy (r (2) = 0.14; p = 0.006). Neither the concentrations of D metabolites nor the metabolic ratios of CYP2D6 and CYP3A4 showed any correlations with cognitive variations. Low CYP2D6 activity and advanced age were associated with high D concentrations. Patients who were treated with CYP2D6 and P-glycoprotein (P-gp) inhibitors also had higher D plasma levels (mean difference = 19.6 ng/mL; p = 0.01) than those who were not. D plasma concentrations, but not cytochrome phenotyping, are associated with cognitive outcomes in AD patients

    Comparative microbial community composition from secondary carbonate (moonmilk) deposits: implications for the Cansiliella servadeii cave hygropetric food web

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    The microbial diversity of moonmilk, a hydrated calcium carbonate speleothem, was evaluated from two Italian caves to provide context for the food web of highly-specialized troglobitic beetles, Cansiliella spp. (Leptodirinae), with distinctive carbon and nitrogen isotope values indicative of a novel food source. The moonmilk and associated percolating waters had low to no extractable chlorophyll, with an average organic C:N ratio of 9, indicating limited allochthonous input and a significant contribution from microbial biomass. The biomass from moonmilk was estimated to be ~104 micro- and meiofaunal individuals per m2 and ~108 microbial cells/ml. Betaproteobacteria dominated the 16S rRNA gene sequences retrieved from the moonmilk from both caves. The distribution of other proteobacterial classes and phyla in the moonmilk were statistically similar to each other, even though the two caves are geographically separated from each other. Comparing the moonmilk gene sequences to sequences from previously described environmental clones or cultured strains revealed the uniqueness of the moonmilk habitat, as ~ 15% of all of the moonmilk sequences were more closely related to each other than to sequences retrieved from any other habitat. However, comparative analyses confirmed that as much as ~34% of the clones sequences were also closely related to environmental clones and cultured strains derived from soil and freshwater habitats, which is likely due to the fact that the putative inoculation source for the moonmilk bacterial communities is from overlying soil and percolating fluids from the surface. Prior to our studies of Cansiliella spp., moonmilk has not been considered a food source for cave animals. Our findings provide unique insight into moonmilk microbial diversity that could reveal the underpinnings of the moonmilk carbon and nitrogen cycle that influences the isotopic composition and the morphological adaptations of the troglobitic beetles associated with the moonmilk

    A unique midgut-associated bacterial community hosted by the cave beetle Cansiliella servadeii (Coleoptera: Leptodirini) reveals parallel phylogenetic divergences from universal gut-specific ancestors

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    Background Cansilella servadeii (Coleoptera) is an endemic troglobite living in deep carbonate caves in North-Eastern Italy. The beetle constantly moves and browses in its preferred habitat, consisting in flowing water and moonmilk, a soft speleothem colonized by microorganisms, and self-preens to convey material from elytra, legs, and antennae towards the mouth. We investigated its inner and outer microbiota using microscopy and DNA-based approaches. Results Abundant microbial cell masses were observed on the external appendages. Cansiliella\u2019s midgut is fully colonized by live microbes and culture-independent analyses yielded nearly 30 different 16S phylotypes that have no overlap with the community composition of the moonmilk. Many of the lineages, dominated by Gram positive groups, share very low similarity to database sequences. However for most cases, notwithstanding their very limited relatedness with existing records, phylotypes could be assigned to bacterial clades that had been retrieved from insect or other animals\u2019 digestive traits. Conclusions Results suggest a history of remote separation from a common ancestor that harboured a set of gut-specific bacteria whose functions are supposedly critical for host physiology. The phylogenetic and coevolutionary implications of the parallel occurrences of these prokaryotic guilds appear to apply throughout a broad spectrum of animal diversity. Their conservation underlies a possibly critical role of precise bacterial assemblages in animal-bacteria interactions
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