3,277 research outputs found

    New experimental limits on neutron - mirror neutron oscillations in the presence of mirror magnetic field

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    Present probes do not exclude that the neutron (nn) oscillation into mirror neutron (nn'), a sterile state exactly degenerate in mass with the neutron, can be a very fast process, in fact faster than the neutron decay itself. This process is sensitive to the magnetic field. Namely, if the mirror magnetic field B\vec{B}' exists at the Earth, nnn-n' oscillation probability can be suppressed or resonantly amplified by the applied magnetic field B\vec{B}, depending on its strength and on the angle β\beta between B\vec{B} and B\vec{B}'. We present the results of ultra-cold neutron storage measurements aiming to check the anomalies observed in previous experiments which could be a signal for nnn-n' oscillation in the presence of mirror magnetic field B0.1B'\sim 0.1~G. Analyzing the experimental data on neutron loses, we obtain a new lower limit on nnn-n' oscillation time τnn>17\tau_{nn'} > 17 s (95 % C.L.) for any BB' between 0.08 and 0.17 G, and τnn/cosβ>27\tau_{nn'}/\sqrt{\cos\beta} > 27 s (95 % C.L.) for any BB' in the interval (0.06÷0.250.06\div0.25) G

    Essential Oils of Dennettia Tripetala Bak. f. Stem Bark and Leaf – Constituents and Biological Activities:

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    The essential oil from the stem bark and leaves of Dennettia tripetala Bak. f. (Annonaceae) growing wild in Ondo State, Nigeria, has been characterized by combined gas chromatography (GC) and gas chromatography-mass spectrometry (GC- MS) analyses. Overall, thirty-six components have been fully identified, thirty-two in the stem-bark oil, and only seven in the leaf oil. In both oils, 2-phenylnitroethane was the main component, ranging between 70 – 76% of the total oils. The profile of the stem bark oil was characterized by a large number of sesquiterpenes, whereas among the few components in the leaf oil, linalool reaches over 17%. When both oils were assayed for antimicrobial activity, only Staphylococcus aureus was susceptible to the stem-bark oil which was more active than leaf oil. For protective effects against UV radiation–induced peroxidation in phosphatidylcholine (PC) liposomes, stem-bark oil also showed greater effectiveness. Activity of the leaf oil against Trichomonas gallinae, was also remarkable

    The impact of GABAergic drugs on TMS-induced brain oscillations in human motor cortex

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    Brain responses to transcranial magnetic stimulation (TMS) as measured with electroencephalography (EEG) have so far been assessed either by TMS-evoked EEG potentials (TEPs), mostly reflecting phase-locked neuronal activity, or time-frequency-representations (TFRs), reflecting oscillatory power arising from a mixture of both evoked (i.e., phase-locked) and induced (i.e., non-phase-locked) responses. Single-pulse TMS of the human primary motor cortex induces a specific pattern of oscillatory changes, characterized by an early (30–200 ms after TMS) synchronization in the α- and β-bands over the stimulated sensorimotor cortex and adjacent lateral frontal cortex, followed by a late (200–400 ms) α- and β-desynchronization over the stimulated and contralateral sensorimotor cortex. As GABAergic inhibition plays an important role in shaping oscillatory brain activity, we sought here to understand if GABAergic inhibition contributes to these TMS-induced oscillations. We tested single oral doses of alprazolam, diazepam, zolpidem (positive modulators of the GABAA receptor), and baclofen (specific GABAB receptor agonist). Diazepam and zolpidem enhanced, and alprazolam tended to enhance while baclofen decreased the early α-synchronization. Alprazolam and baclofen enhanced the early β-synchronization. Baclofen enhanced the late α-desynchronization, and alprazolam, diazepam and baclofen enhanced the late β-desynchronization. The observed GABAergic drug effects on TMS-induced α- and β-band oscillations were not explained by drug-induced changes on corticospinal excitability, muscle response size, or resting-state EEG power. Our results provide first insights into the pharmacological profile of TMS-induced oscillatory responses of motor cortex

    Predictors of severe hyperbiliruniaemia in HIV-infected patients treated with atazanavir (ATV)

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    Methods HIV-infected subjects on ATV/ritonavir containing stable HAART regimen were included. ATV plasma concentrations were measured 24 hours after the last dose by HPLC with UV detector. Polymorphism at the uridin-glocoronosyl-transferase 1A1 (UGT1A1) was examined in DNA extracted from blood mononuclear cells, to identify subjects with Gilbert's syndrome. The correlation between bilirubin plasma levels, ATV concentration and polymorphism of UGT1A1 (defined as the presence than at least one TA7 allele) were evaluated by multivariate linear regression (other covariates included: gender, age, CD4 count, months of ATV exposure). Predictors of severe hyperbilirubinemia (>2.5 μmol/l; grade 3) were evaluated by multivariate logistic regression (polymorphism at UGT1A1, Cmin, BMI, age included as covariates)

    Genetic control of chemokines in severe human internal carotid artery stenosis

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    Background and purpose: Atherosclerosis is an inflammatory disease. Chemokines and chemokine receptors are known to be involved in atherogenesis. Common single nucleotide polymorphisms (SNPs) affect transcription in response to inflammatory stimuli. The aim of this study was to evaluate the correlations between MCP-1, RANTES, SDF-1, CCR2, and CCR5 gene polymorphisms with increased risk of internal carotid artery (ICA) stenosis. Methods: Hundred and twelve patients, consecutively recruited for ICA occlusive disease, and 282 controls were genotyped for MCP-1-2518G, RANTES-403A, CCR5D32, CCR2 V64I, and SDF-1-801A polymorphisms. Results: The frequency of the SDF-1A allele was significantly different between cases and controls: 0.32 vs. 0.20, respectively (OR 1.81; 95% CI 1.25\u20132.60; p = 0.007). The frequency of the RANTES-403G allele was significantly higher in patients with stenosis >70% (OR, 2.45; 95% CI 1.12\u20135.71; p = 0.015). No significant differences were observed with the other polymorphisms. Conclusion: The reported results seem to correlate the polymorphisms of the genes encoding for SDF-1, RANTES with pathogenesis and progression of ICA occlusive disease. Although suggestive, these results need confirmation in prospective cross-sectional studies

    SOXS: a wide band spectrograph to follow up transients

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    SOXS (Son Of X-Shooter) will be a spectrograph for the ESO NTT telescope capable to cover the optical and NIR bands, based on the heritage of the X-Shooter at the ESO-VLT. SOXS will be built and run by an international consortium, carrying out rapid and longer term Target of Opportunity requests on a variety of astronomical objects. SOXS will observe all kind of transient and variable sources from different surveys. These will be a mixture of fast alerts (e.g. gamma-ray bursts, gravitational waves, neutrino events), mid-term alerts (e.g. supernovae, X-ray transients), fixed time events (e.g. close-by passage of minor bodies). While the focus is on transients and variables, still there is a wide range of other astrophysical targets and science topics that will benefit from SOXS. The design foresees a spectrograph with a Resolution-Slit product ~ 4500, capable of simultaneously observing over the entire band the complete spectral range from the U- to the H-band. The limiting magnitude of R~20 (1 hr at S/N~10) is suited to study transients identified from on-going imaging surveys. Light imaging capabilities in the optical band (grizy) are also envisaged to allow for multi-band photometry of the faintest transients. This paper outlines the status of the project, now in Final Design Phase.Comment: 12 pages, 14 figures, to be published in SPIE Proceedings 1070

    ALL blasts drive primary mesenchymal stromal cells to increase asparagine availability during asparaginase treatment

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    Mechanisms underlying the resistance of acute lymphoblastic leukemia (ALL) blasts to L-asparaginase are still incompletely known. Here we demonstrate that human primary bone marrow mesenchymal stromal cells (MSCs) successfully adapt to L-asparaginase and markedly protect leukemic blasts from the enzyme-dependent cytotoxicity through an amino acid tradeoff. ALL blasts synthesize and secrete glutamine, thus increasing extracellular glutamine availability for stromal cells. In turn, MSCs use glutamine, either synthesized through glutamine synthetase (GS) or imported, to produce asparagine, which is then extruded to sustain asparagine-auxotroph leukemic cells. GS inhibition prevents mesenchymal cells adaptation to L-asparaginase, lowers glutamine secretion by ALL blasts, and markedly hinders the protection exerted by MSCs on leukemic cells. The pro-survival amino acid exchange is hindered by the inhibition or silencing of the asparagine efflux transporter SNAT5, which is induced in mesenchymal cells by ALL blasts. Consistently, primary MSCs from ALL patients express higher levels of SNAT5 (P <.05), secrete more asparagine (P <.05), and protect leukemic blasts (P <.05) better than MSCs isolated from healthy donors. In conclusion, ALL blasts arrange a pro-leukemic amino acid trade-off with bone marrow mesenchymal cells, which depends on GS and SNAT5 and promotes leukemic cell survival during L-asparaginase treatment
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