3,949 research outputs found
Enhanced antioxidant effect of trans-resveratrol: potential of binary systems with polyethylene glycol and cyclodextrin.
Abstract Trans-resveratrol, a polyphenol extracted from Vitis vinifera, has different beneficial effects following its administration on the skin. Here the potential use of binary systems to enhance in vitro and in vivo activity of trans-resveratrol was investigated. Thus the aqueous solubility of trans-resveratrol was investigated in the presence of growing concentrations of polyethylene glycol (PEG) or β-cyclodextrin (βCD) as solubilizing excipients. Then, the solid dispersion of trans-resveratrol with PEG or inclusion complexes trans-resveratrol/βCD were prepared and characterised by different methods. Cytotoxicity and inhibition of reactive oxygen species (ROS) following H2O2 challenge in the presence of trans-resveratrol, alone or associated to the excipients, was evaluated on human keratinocyte HaCaT cell line. Both the trans-resveratrol-containing binary systems induced significant reduction of H2O2-induced ROS production, especially in the case of βCD that was selected for the following phase of the study. Thus, the effect of a cream containing trans-resveratrol, alone or associated to βCD, on different skin parameters such as corneometry, colorimetry and elastometry, was evaluated on human volunteers. All patients showed a visible improvement of clinical conditions with a remarkable decrease of aging signs, but this effect was higher of the hemi face treated with the βCD-containing formulation versus formulation containing trans-resveratrol alone
Stellar Population gradients in galaxy discs from the CALIFA survey
While studies of gas-phase metallicity gradients in disc galaxies are common,
very little has been done in the acquisition of stellar abundance gradients in
the same regions. We present here a comparative study of the stellar
metallicity and age distributions in a sample of 62 nearly face-on, spiral
galaxies with and without bars, using data from the CALIFA survey. We measure
the slopes of the gradients and study their relation with other properties of
the galaxies. We find that the mean stellar age and metallicity gradients in
the disc are shallow and negative. Furthermore, when normalized to the
effective radius of the disc, the slope of the stellar population gradients
does not correlate with the mass or with the morphological type of the
galaxies. Contrary to this, the values of both age and metallicity at 2.5
scale-lengths correlate with the central velocity dispersion in a similar
manner to the central values of the bulges, although bulges show, on average,
older ages and higher metallicities than the discs. One of the goals of the
present paper is to test the theoretical prediction that non-linear coupling
between the bar and the spiral arms is an efficient mechanism for producing
radial migrations across significant distances within discs. The process of
radial migration should flatten the stellar metallicity gradient with time and,
therefore, we would expect flatter stellar metallicity gradients in barred
galaxies. However, we do not find any difference in the metallicity or age
gradients in galaxies with without bars. We discuss possible scenarios that can
lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&
Scholar-activists in an expanding European food sovereignty movement
This article analyzes the roles, relations, and positions of scholar-activists in the European food sovereignty movement. In doing so, we document, make visible and question the political dimensions of researchers' participation in the movement. We argue that scholar-activists are part of the movement, but are distinct from the affected constituencies, put in place to ensure adequate representation of key movement actors. This is because scholar-activists lack a collective identity, have no processes to formulate collective demands, and no mechanisms for inter-researcher and researchers-movement communication. We reflect on whether and how scholar-activists could organize, and discuss possible pathways for a more cohesive and stronger researcher engagement in the movement.</p
ROSAT observations of X-ray emission from planetary nebulae
We have searched the entire ROSAT archive for useful observations to study
X-ray emission from Galactic planetary nebulae (PNs). The search yields a
sample of 63 PNs, which we call the ROSAT PN sample. About 20-25% of this
sample show X-ray emission; these include 13 definite detections and three
possible detections (at a 2-sigma level). All X-ray sources in these PNs are
concentrated near the central stars. Only A 30, BD+30 3639, and NGC 6543 are
marginally resolved by the ROSAT instruments. Three types of X-ray spectra are
seen in PNs. Type 1 consists of only soft X-ray emission (<0.5 keV), peaks at
0.1-0.2 keV, and can be fitted by blackbody models at temperatures 1-2 10^5 K.
Type 2 consists of harder X-ray emission, peaks at >0.5 keV, and can be fitted
by thin plasma emission models at temperatures of a few 10^6 K. Type 3 is a
composite of a bright Type 1 component and a fainter Type 2 component.
Unresolved soft sources with Type 1 spectra or the soft component of Type 3
spectra are most likely photospheric emission from the hot central stars.
Absorption cross sections are large for these soft-energy photons; therefore,
only large, tenuous, evolved PNs with hot central stars and small absorption
column densities have been detected. The origin of hard X-ray emission from PNs
is uncertain. PNs with Type 2 spectra are small, dense, young nebulae with
relatively cool (<<10^5 K) central stars, while PNs with Type 3 X-ray spectra
are large, tenuous, evolved nebulae with hot central stars. The hard X-ray
luminosities are also different between these two types of PNs, indicating
perhaps different origins of their hard X-ray emission. Future Chandra and XMM
observations with high spatial and spectral resolution will help to understand
the origin of hard X-ray emission from PNs.Comment: To be published in The Astrophysical Journal Supplement Series. 21
pages, 7 figures, 5 table
H-alpha Kinematics of the SINGS Nearby Galaxies Survey. II
This is the second part of an H-alpha kinematics follow-up survey of the
Spitzer Infrared Nearby Galaxies Survey (SINGS) sample. The aim of this program
is to shed new light on the role of baryons and their kinematics and on the
dark/luminous matter relation in the star forming regions of galaxies, in
relation with studies at other wavelengths. The data for 37 galaxies are
presented. The observations were made using Fabry-Perot interferometry with the
photon-counting camera FaNTOmM on 4 different telescopes, namely the
Canada-France-Hawaii 3.6m, the ESO La Silla 3.6m, the William Herschel 4.2m,
and the Observatoire du mont Megantic 1.6m telescopes. The velocity fields are
computed using custom IDL routines designed for an optimal use of the data. The
kinematical parameters and rotation curves are derived using the GIPSY
software. It is shown that non-circular motions associated with galactic bars
affect the kinematical parameters fitting and the velocity gradient of the
rotation curves. This leads to incorrect determinations of the baryonic and
dark matter distributions in the mass models derived from those rotation
curves.Comment: 18 pages, 5 figures, 4 tables. Accepted for publication in MNRAS. All
high-res. figures are available at
http://www.astro.umontreal.ca/fantomm/singsII
Design of a precision compactor for use in guided bone regeneration in the area of oral surgery
During the processes of guided bone regeneration in the maxillary bones, which aim to recover or preserve support tissue for the placement of implants on which dental prostheses are retained, the use of various particulate graft biomaterials from different sources (animal or synthetic) is standardized. At present, the pressure of compaction of this material in the recipient bone is manual, dependent on the clinician, although there is some scientific evidence on the effects of different compressive forces on angiogenesis and prognosis of the regeneration of the grafted areas. The aim of the present study is to design, calibrate and verify in vitro a compaction instrument for clinical use, which allows a controlled and precise compaction pressure of the particulate graft biomaterial and standardize the procedure. The designed instrument is a precision compactor of adequate size for proper intra and extraoral clinical manageability and manufactured in a sterilizable material by autoclaving. The range of compression that allows (0 -1, 82 Newton), is within the forces that are commonly applied in surgery and that have been determined by a specific test on 8 oral surgeons. Instrument calibration has been performed by an independent accredited company. The testing of the instrument was carried out by an in vitro test where the biomaterial was compacted at different forces (0, 80 and 1, 82 Newton) and was observed by a computerized micro-tomography that when increasing the compression force, decreased the space between particles provided for the migration and proliferation of new blood vessels and cells.
Durante los procedimientos de regeneración ósea guiada en los huesos maxilares, que tienen como objetivo recuperar o preservar tejido de soporte para la colocación de implantes sobre los que se retienen las prótesis dentales, está estandarizado el uso de diversos biomateriales de injerto particulado de diferente procedencia (animal o sintético). En la actualidad la presión de compactación de dicho material en el hueso receptor es manual, clínico dependiente, pese a que existe cierta evidencia científica sobre los efectos de las diferentes fuerzas de compresión en la angiogénesis y pronóstico de la regeneración de las zonas injertadas.
El objetivo del presente estudio es el de diseñar, calibrar y comprobar in vitro un instrumento de compactación para uso clínico, que permita una presión de compactación controlada y precisa del biomaterial de injerto particulado y estandarizar el procedimiento.
El instrumento diseñado es un compactador de precisión de tamaño adecuado para una correcta manejabilidad clínica intra y extraoral y fabricado en un material esterilizable por autoclavado.
El rango de compresión que permite (0 – 1, 82 Newton), está dentro de las fuerzas que se aplican comúnmente en cirugía y que se han determinado mediante una prueba específica sobre 8 cirujanos orales. La calibración del instrumento se ha realizado por una empresa acreditada independiente.
La comprobación del instrumento se ha realizado mediante un ensayo in vitro donde se compactó el biomaterial a diferentes fuerzas (0, 80 y 1, 82 Newton) y se observó mediante micro-tomografía computerizada que al aumentar la fuerza de compresión disminuía el espacio entre partículas provisto para la migración y proliferación de los nuevos vasos sanguíneos y células
The effects of spatial resolution on Integral Field Spectrograph surveys at different redshifts. The CALIFA perspective
Over the past decade, 3D optical spectroscopy has become the preferred tool
for understanding the properties of galaxies and is now increasingly used to
carry out galaxy surveys. Low redshift surveys include SAURON, DiskMass,
ATLAS3D, PINGS and VENGA. At redshifts above 0.7, surveys such as MASSIV, SINS,
GLACE, and IMAGES have targeted the most luminous galaxies to study mainly
their kinematic properties. The on-going CALIFA survey () is the
first of a series of upcoming Integral Field Spectroscopy (IFS) surveys with
large samples representative of the entire population of galaxies. Others
include SAMI and MaNGA at lower redshift and the upcoming KMOS surveys at
higher redshift. Given the importance of spatial scales in IFS surveys, the
study of the effects of spatial resolution on the recovered parameters becomes
important. We explore the capability of the CALIFA survey and a hypothetical
higher redshift survey to reproduce the properties of a sample of objects
observed with better spatial resolution at lower redshift. Using a sample of
PINGS galaxies, we simulate observations at different redshifts. We then study
the behaviour of different parameters as the spatial resolution degrades with
increasing redshift.Comment: 20 pages, 16 figures. Accepted for publication in A&
Predictors Of Positivity Of [F-18]F-Choline PET-CT In Prostate Cancer Recurrence. Preliminary Results
EP-173
Aim/Introduction: To analyze the validity of [18F]F-Choline PET-CT results in prostate cancer recurrence in our daily practice, based on theoretical cut-off points of prostatespecific antigen (PSA), its kinetic, and PSA doubling time (PSADT), to identify predictors of positivity and modify the indication criteria. Materials and
Methods: Prior to the validity analysis, a descriptive, prospective analysis of consecutive patients with prostate cancer treated with curative intent by radical prostatectomy (RP) or radiotherapy (RT), who underwent PET-CT scan with recurrence criteria: PSA =1 or PSA 0.4-1 with PSADT Nadir + 2 after RT, was performed.
Results: From April to December 2019, 69 patients were included, 40 were treated with RP (58%) and 29 with RT (42%). In 45 patients (65%) PET-CT was able to identify recurrence of the disease (positive PET) and in 24 it was not (negative PET). Of patients treated with RP, 82, 5% (33/40) had PSA>1, and of those, 61% were positive PET. 17, 5% (7/40) had PSA6months (28/69), in 71% if PSADT6 months, in 61% and 92% if PSADT<6 months and in 77% and 100% if PSADT<3 months.
Conclusion: Preliminarily and awaiting validation, it seems that PSA>1 after RP or Nadir +2 after RT is an indicator of PET-CT. There seems to be a tendency that shows that PSA<1 after RP is an indicator of PET-CT if PSADT<3 months. PSADT <3 or <6 months could be the best predictor of positivity of PET-CT with [18F]F-Choline in recurrent prostate cancer
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