4,229 research outputs found

    DNA methylation enables recurrent endogenization of giant viruses in an animal relative.

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    5-Methylcytosine (5mC) is a widespread silencing mechanism that controls genomic parasites. In eukaryotes, 5mC has gained complex roles in gene regulation beyond parasite control, yet 5mC has also been lost in many lineages. The causes for 5mC retention and its genomic consequences are still poorly understood. Here, we show that the protist closely related to animals Amoebidium appalachense features both transposon and gene body methylation, a pattern reminiscent of invertebrates and plants. Unexpectedly, hypermethylated genomic regions in Amoebidium derive from viral insertions, including hundreds of endogenized giant viruses, contributing 14% of the proteome. Using a combination of inhibitors and genomic assays, we demonstrate that 5mC silences these giant virus insertions. Moreover, alternative Amoebidium isolates show polymorphic giant virus insertions, highlighting a dynamic process of infection, endogenization, and purging. Our results indicate that 5mC is critical for the controlled coexistence of newly acquired viral DNA into eukaryotic genomes, making Amoebidium a unique model to understand the hybrid origins of eukaryotic DNA

    Antioxidant Effects of Quercetin and Catechin Encapsulated into PLGA Nanoparticles

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    Polymeric nanoparticles (PLGA) have been developed for the encapsulation and controlled release of quercetin and catechin. Nanoparticles were fabricated using a solvent displacement method. Physicochemical properties were measured by light scattering, scanning electron microscopy and ζ-potential, X-ray diffraction, infrared spectroscopy and differential scanning calorimetry. Encapsulation efficiency and in vitro release profiles were obtained from differential pulse voltammetry experiments. Antioxidant properties of free and encapsulated flavonoids were determined by TBARS, fluorescence spectroscopy and standard chelating activity methods. Relatively small (d≈ 400 nm) polymeric nanoparticles were obtained containing quercetin or catechin in a non-crystalline form (EE ≈ 79%) and the main interactions between the polymer and each flavonoid were found to consist of hydrogen bonds. In vitro release profiles were pH-dependant, the more acidic pH, the faster release of each flavonoid from the polymeric nanoparticles. The inhibition of the action of free radicals and chelating properties, were also enhanced when quercetin and catechin were encapsulated within PLGA nanoparticles. The information obtained from this study will facilitate the design and fabrication of polymeric nanoparticles as possible oral delivery systems for encapsulation, protection and controlled release of flavonoids aimed to prevent oxidative stress in human body or food products

    Electron energy loss and induced photon emission in photonic crystals

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    The interaction of a fast electron with a photonic crystal is investigated by solving the Maxwell equations exactly for the external field provided by the electron in the presence of the crystal. The energy loss is obtained from the retarding force exerted on the electron by the induced electric field. The features of the energy loss spectra are shown to be related to the photonic band structure of the crystal. Two different regimes are discussed: for small lattice constants aa relative to the wavelength of the associated electron excitations λ\lambda, an effective medium theory can be used to describe the material; however, for a∌λa\sim\lambda the photonic band structure plays an important role. Special attention is paid to the frequency gap regions in the latter case.Comment: 12 pages, 7 figure

    Emission lines from rotating proto-stellar jets with variable velocity profiles. I. Three-dimensional numerical simulation of the non-magnetic case

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    Using the Yguazu-a three-dimensional hydrodynamic code, we have computed a set of numerical simulations of heavy, supersonic, radiatively cooling jets including variabilities in both the ejection direction (precession) and the jet velocity (intermittence). In order to investigate the effects of jet rotation on the shape of the line profiles, we also introduce an initial toroidal rotation velocity profile, in agreement with some recent observational evidence found in jets from T Tauri stars which seems to support the presence of a rotation velocity pattern inside the jet beam, near the jet production region. Since the Yguazu-a code includes an atomic/ionic network, we are able to compute the emission coefficients for several emission lines, and we generate line profiles for the H, [O I]6300, [S II]6716 and [N II]6548 lines. Using initial parameters that are suitable for the DG Tau microjet, we show that the computed radial velocity shift for the medium-velocity component of the line profile as a function of distance from the jet axis is strikingly similar for rotating and non-rotating jet models. These findings lead us to put forward some caveats on the interpretation of the observed radial velocity distribution from a few outflows from young stellar objects, and we claim that these data should not be directly used as a doubtless confirmation of the magnetocentrifugal wind acceleration models.Comment: 15 pages, 8 figures. Accepted to publication in Astronomy and Astrophysic

    Studies on the clinical significance of nonesterified and total cholesterol in urine

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    Gas-liquid chromatographic determinations of nonesterified and total urinary cholesterol were performed in 137 normals, 264 patients with various internal diseases without evidence of neoplasias or diseases of the kidney or urinary tract, 497 patients with malignancies and 236 patients with diseases of the kidney, urinary tract infections or prostatic adenoma with residual urine. A normal range (mean±2 SD) of 0.2–2.2 mg/24 hours nonesterified cholesterol (NEC) and of 0.3–3.0 mg/24 hours total cholesterol (TC) was calculated. Values of urinary cholesterol excretion were independent of age and sex and did not correlate with cholesterol levels in plasma. Patients with various internal diseases, without evidence of neoplasias nor diseases of the kidney or obstruction of the urinary tract, showed normal urinary cholesterol excretions, as did patients with infections of the urinary tract. However, elevated urinary cholesterol was found in patients with diseases of the kidney or urinary tract obstruction (prostatic adenoma with residual urine), malignant diseases of the urogenital tract and metastasing carcinoma of the breast. In patients with other malignant diseases urinary cholesterol was usually normal. Lesions of the urothelial cell membranes are considered to be the most likely cause of urinary cholesterol hyperexcretion. The clinical value of urinary cholesterol determinations as a possible screening test for urogenital carcinomas in unselected populations is limited by lacking specificity, expensive methodology and low prevalence of the mentioned carcinomas, although elevated urinary cholesterol excretions have been observed in early clinical stages of urogenital cancers

    Primera encuesta de "Nuestro cinema"

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    Cabello, A.; CastellĂłn DĂ­az Anfurso, J.; GonzĂĄlez, J.; De Mendoza, AH. (1932). Primera encuesta de "Nuestro cinema". Nuestro cinema. (4):97-104. http://hdl.handle.net/10251/42796.ImportaciĂłn Masiva97104

    Complete inhibition of extranodal dissemination of lymphoma by edelfosine-loaded lipid nanoparticles

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    Lipid nanoparticles (LN) made of synthetic lipids CompritolŸ 888 ATO and PrecirolŸ ATO 5 were developed, presenting an average size of 110.4 ± 2.1 nm and 103.1 ± 2.9 nm, for CompritolŸ and PrecirolŸ, respectively, and encapsulation efficiency above 85 % for both type of lipids. These LN decrease the hemolytic toxicity of the drug by 90 %. Pharmacokinetic and biodistribution profiles of the drug were studied after intravenous and oral administration of edelfosine-containing LN, providing an increase in relative oral bioavailability of 1500 % after a single oral administration of drug-loaded LN, maintaining edelfosine plasma levels over 7 days in contrast to a single oral administration of edelfosine solution, which presents a relative oral bioavailability of 10 %. Moreover, edelfosine-loaded LN showed a high accumulation of the drug in lymph nodes and resulted in slower tumor growth than the free drug in a murine lymphoma xenograft model, as well as potent extranodal dissemination inhibition

    Ultra high performance liquid chromatography–tandem mass spectrometry method for cyclosporine a quantification in biological samples and lipid nanosystems

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    Cyclosporine A (CyA) is an immunosuppressant cyclic undecapeptide used for the prevention of organ transplant rejection and in the treatment of several autoimmune disorders. An ultra high performance liquid chromatography–tandem mass spectrometry method (UHPLC–MS/MS) to quantify CyA in lipid nanosystems and mouse biological matrices (whole blood, kidneys, lungs, spleen, liver, heart, brain, stomach and intestine) was developed and fully validated. Chromatographic separation was performed on an Acquity UPLCÂź BEH C18 column with a gradient elution consisting of methanol and 2 mM ammonium acetate aqueous solution containing 0.1% formic acid at a flow rate of 0.6 mL/min. Amiodarone was used as internal standard (IS). Retention times of IS and CyA were 0.69 min and 1.09 min, respectively. Mass spectrometer operated in electrospray ionization positive mode (ESI+) and multiple reaction monitoring (MRM) transitions were detected, m/z 1220.69 → 1203.7 for CyA and m/z 646 → 58 for IS. The extraction method from biological samples consisted of a simple protein precipitation with 10% trichloroacetic acid aqueous solution and acetonitrile and 5 ÎŒL of supernatant were directly injected into the UHPLC–MS/MS system. Linearity was observed between 0.001 ÎŒg/mL–2.5 ÎŒg/mL (r ≄ 0.99) in all matrices. The precision expressed in coefficient of variation (CV) was below 11.44% and accuracy in bias ranged from −12.78% to 7.99% including methanol and biological matrices. Recovery in all cases was above 70.54% and some matrix effect was observed. CyA was found to be stable in post-extraction whole blood and liver homogenate samples exposed for 6 h at room temperature and 72 h at 4 °C. The present method was successfully applied for quality control of lipid nanocarriers as well as in vivo studies in BALB/c mice

    Aperture effects on the oxygen abundance determinations from CALIFA data

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    This paper aims at providing aperture corrections for emission lines in a sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey (CALIFA) database. In particular, we explore the behavior of the log([OIII]5007/Hbeta)/([NII]6583/Halpha) (O3N2) and log[NII]6583/Halpha (N2) flux ratios since they are closely connected to different empirical calibrations of the oxygen abundances in star forming galaxies. We compute median growth curves of Halpha, Halpha/Hbeta, O3N2 and N2 up to 2.5R_50 and 1.5 disk R_eff. The growth curves simulate the effect of observing galaxies through apertures of varying radii. The median growth curve of the Halpha/Hbeta ratio monotonically decreases from the center towards larger radii, showing for small apertures a maximum value of ~10% larger than the integrated one. The median growth curve of N2 shows a similar behavior, decreasing from the center towards larger radii. No strong dependence is seen with the inclination, morphological type and stellar mass for these growth curves. Finally, the median growth curve of O3N2 increases monotonically with radius. However, at small radii it shows systematically higher values for galaxies of earlier morphological types and for high stellar mass galaxies. Applying our aperture corrections to a sample of galaxies from the SDSS survey at 0.02<=z<=0.3 shows that the average difference between fiber-based and aperture corrected oxygen abundances, for different galaxy stellar mass and redshift ranges, reaches typically to ~11%, depending on the abundance calibration used. This average difference is found to be systematically biased, though still within the typical uncertainties of oxygen abundances derived from empirical calibrations. Caution must be exercised when using observations of galaxies for small radii (e.g. below 0.5R_eff) given the high dispersion shown around the median growth curves.Comment: Accepted for publication in Ap
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