66 research outputs found
Anti-atherogenic properties associated with the antioxidant activity from the hydrophilic extracts of Halimeda incrassata (Chlorophyta, Bryopsidales)
Seaweeds are a source of natural antioxidants having potential application in oxidative stress and associated diseases. In this work, anti-atherogenic properties associated with the antioxidant activity from the hydrophilic extracts of Halimeda incrassata were studied. The phenolic content assessed inthe aqueous extract and fraction phenolic acids (FPA) was 0.13 ± 0.05 and 0.47 ± 0.09 mg of gallic acid equivalents (GAE)/g dry seaweed, respectively. In DPPH?, radical scavenging assay fractions exhibited a dependent concentration. The seaweeds extract inhibited the desoxirribose oxidation in the presenceor absence of EDTA (IC50 = 1.91± 0.09 mg/mL) (IC50 = 2.95 ± 0.01 mg/mL). In vivo antioxidant properties of FPA-H.incrassata were investigated in rats with a CCl4-induced liver injury. Pre-treatment with H.incrassata led to approximately 50% reductions in liver TBARS levels. The treatment with H. incrassataFPA also increased the activity of the CAT enzyme, which in turn resulted in an enhanced antioxidantdefense. The expression of Catalase by PCR-RT technique demonstrated a higher gene expression when compared with that which was observed in the CCl 4-treated group. Antiatherogenic properties were studied in the inhibition of lipoprotein oxidation mediated by Cu2+ or HRP/H2O2, free radicalscavenging, and metal ion chelation, and it was dose dependent with a higher concentration needed for the aqueous extract than for the FPA fraction. Antioxidant activity was also improved in macrophages as evaluated in the cell supernatant (by TBARS formation); and by luminol enhanced chemiluminescence after cell activation with zymosan; and a degree of cell lipoperoxidation wasdecreased by the Halimeda incrassata extract. The results of this work add to the antioxidant potential of the seaweed for its application in oxidative stress associated conditions.Fil: Vidal-Novoa, Alexis. Universidad de la Habana. Facultad de Biología; CubaFil: Costa-Mugica, Ariadna. Universidad de la Habana. Facultad de Biología; CubaFil: Zulueta Díaz, Yenisleidy de Las Mercedes. Universidad de la Habana. Facultad de Biología; Cuba. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; ArgentinaFil: Diaz-Gutierrez, Daylín. Universidad de la Habana. Facultad de Biología; CubaFil: de Oliveira e Silva, Ana, Mara. Universidade de Sao Paulo; BrasilFil: Vazquez, Ana María. Center For Molecular Inmunology; CubaFil: Claudina, Zaldívar-Munoz. Universidad de la Habana. Facultad de Biología; CubaFil: Dalva, Assuncao Portari de Mancini. Institute Butantan Sao Paulo; BrasilFil: Mancini-Filho, Jorge. Universidade de Sao Paulo; Brasi
Phase Referencing in Optical Interferometry
One of the aims of next generation optical interferometric instrumentation is
to be able to make use of information contained in the visibility phase to
construct high dynamic range images. Radio and optical interferometry are at
the two extremes of phase corruption by the atmosphere. While in radio it is
possible to obtain calibrated phases for the science objects, in the optical
this is currently not possible. Instead, optical interferometry has relied on
closure phase techniques to produce images. Such techniques allow only to
achieve modest dynamic ranges. However, with high contrast objects, for faint
targets or when structure detail is needed, phase referencing techniques as
used in radio interferometry, should theoretically achieve higher dynamic
ranges for the same number of telescopes. Our approach is not to provide
evidence either for or against the hypothesis that phase referenced imaging
gives better dynamic range than closure phase imaging. Instead we wish to
explore the potential of this technique for future optical interferometry and
also because image reconstruction in the optical using phase referencing
techniques has only been performed with limited success. We have generated
simulated, noisy, complex visibility data, analogous to the signal produced in
radio interferometers, using the VLTI as a template. We proceeded with image
reconstruction using the radio image reconstruction algorithms contained in
AIPS IMAGR (CLEAN algorithm). Our results show that image reconstruction is
successful in most of our science cases, yielding images with a 4
milliarcsecond resolution in K band. (abridged)Comment: 11 pages, 36 figure
The Radio Properties of Composite LINER/HII Galaxies
Arcsec-resolution VLA observations -- newly obtained as well as published --
of 40 nearby galaxies are discussed, completing a study of the radio properties
of a magnitude-limited sample of nearby galaxies of the composite LINER/HII
type. Our results reveal an overall detection rate of at least 25% AGN
candidates among these composite sources. The general properties of these AGN
candidates, as compared to non-AGN composite sources and HII galaxies, are
discussed.Comment: Accepted for publication in ApJ
The Nature of Composite LINER/HII Galaxies, As Revealed from High-Resolution VLA Observations
A sample of 37 nearby galaxies displaying composite LINER/HII and pure HII
spectra was observed with the VLA in an investigation of the nature of their
weak radio emission. The resulting radio contour maps overlaid on optical
galaxy images are presented here, together with an extensive literature list
and discussion of the individual galaxies. Radio morphological data permit
assessment of the ``classical AGN'' contribution to the global activity
observed in these ``transition'' LINER galaxies. One in five of the latter
objects display clear AGN characteristics: these occur exclusively in
bulge-dominated hosts.Comment: 31 pages, 27 figures, accepted by ApJ
Computational methods for the image segmentation of pigmented skin lesions: a review
Background and objectives: Because skin cancer affects millions of people worldwide, computational
methods for the segmentation of pigmented skin lesions in images have been
developed in order to assist dermatologists in their diagnosis. This paper aims to present a
review of the current methods, and outline a comparative analysis with regards to several
of the fundamental steps of image processing, such as image acquisition, pre-processing
and segmentation.
Methods: Techniques that have been proposed to achieve these tasks were identified and
reviewed. As to the image segmentation task, the techniques were classified according to
their principle.
Results: The techniques employed in each step are explained, and their strengths and weaknesses
are identified. In addition, several of the reviewed techniques are applied to macroscopic
and dermoscopy images in order to exemplify their results.
Conclusions: The image segmentation of skin lesions has been addressed successfully in many
studies; however, there is a demand for new methodologies in order to improve the efficiency
Preliminary analysis of the genetic variability of two natural beds of the Scallop Euvola ziczac (Linnaeus, 1758) in Brazil
Euvola ziczac (formerly Pecten ziczac), a simultaneous hermaphroditic scallop was heavily fished in
Brazil between 1972 and 1980. The production peaked in 1980 with 8,800 tons and was followed by the
total collapse of the resource. In order to investigate the possible loss of genetic variability of the stock
associated to overfishing and self-fertilization, the polymorphism of phosphoglucomutase (PGM) and
glucose phosphate isomerase (GPI) was analyzed by electrophoresis of the adductor muscle of scallops
from São Francisco (26° 20.583S; 48° 16.507W) and Bom Abrigo (25° 28.735S; 47° 37.621W) beds;
the southern and northern extremes of the scallop fishing ground, respectively. Animals from São
Francisco showed a strong deficiency of heterozygosity for GPI and PGM. In addition, PGM showed
*exclusive alleles for each bed. Such results coupled with other information about the species
suggested the following hypothesis: a) the stock was a metapopulation with at least two populations; b)
some reproductive isolation might be occurring which might be influenced by conditions of larval
transport and by the extremely low densities of scallops; c) presently, the stock seemed to be mostly
maintained through self-fertilization; d) São Francisco could constitute a source-area, contributing with
larvae and recruits to Bom Abrigo and other areas; e) both beds were suffering a genetic
homogenization more evident in São Francisco. Such hypothesis needed to be investigated in order to
furnish guidelines for future programs of recovery and management of the resource.info:eu-repo/semantics/publishedVersio
Phase Closure Image Reconstruction for Future VLTI Instrumentation
Classically, optical and near-infrared interferometry have relied on closure
phase techniques to produce images. Such techniques allow us to achieve modest
dynamic ranges. In order to test the feasibility of next generation optical
interferometers in the context of the VLTI-spectro-imager (VSI), we have
embarked on a study of image reconstruction and analysis. Our main aim was to
test the influence of the number of telescopes, observing nights and
distribution of the visibility points on the quality of the reconstructed
images. Our results show that observations using six Auxiliary Telescopes (ATs)
during one complete night yield the best results in general and is critical in
most science cases; the number of telescopes is the determining factor in the
image reconstruction outcome. In terms of imaging capabilities, an optical, six
telescope VLTI-type configuration and ~200 meter baseline will achieve 4 mas
spatial resolution, which is comparable to ALMA and almost 50 times better than
JWST will achieve at 2.2 microns. Our results show that such an instrument will
be capable of imaging, with unprecedented detail, a plethora of sources,
ranging from complex stellar surfaces to microlensing events.Comment: 11 pages, 26 figure
Bulgeless Galaxies at Intermediate Redshift: Sample Selection, Color Properties, and the Existence of Powerful Active Galactic Nuclei
We present a catalog of bulgeless galaxies, which includes 19,225 objects selected in four of the deepest, largest multi-wavelength data sets available—COSMOS, AEGIS, GEMS, and GOODS—at intermediate redshift (0.4 ≤ z ≤ 1.0). The morphological classification was provided by the Advanced Camera for Surveys General Catalog (ACS-GC), which used publicly available data obtained with the ACS instrument on the Hubble Space Telescope. Rest-frame photometric quantities were derived using kcorrect. We analyze the properties of the sample and the evolution of pure-disk systems with redshift. Very massive [log (M_*/M_☉) > 10.5] bulgeless galaxies contribute to ~30% of the total galaxy population number density at z ≥ 0.7, but their number density drops substantially with decreasing redshift. We show that only a negligible fraction of pure disks appear to be quiescent systems, and red sequence bulgeless galaxies show indications of dust-obscured star formation. X-ray catalogs were used to search for X-ray emission within our sample. After visual inspection and detailed parametric morphological fitting we identify 30 active galactic nuclei (AGNs) that reside in galaxies without a classical bulge. The finding of such peculiar objects at intermediate redshift shows that while AGN growth in merger-free systems is a rare event (0.2% AGN hosts in this sample of bulgeless galaxies), it can indeed happen relatively early in the history of the universe
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