118 research outputs found
Design of a nasal spray based on cardiospermum halicacabum extract loaded in phospholipid vesicles enriched with gelatin or chondroitin sulfate
The extract of Cardiospermum halicacabum L. (C. halicacabum) obtained from flower, leaf and vine was loaded into modified phospholipid vesicles aiming at obtaining sprayable, biocompatible and effective nasal spray formulations for the treatment of nasopharyngeal diseases. Penetration enhancer-containing vesicles (PEVs) and hyalurosomes were formulated, and stabilized by adding a commercial gelatin from fish (20 mg/mL) or chondroitin sulfate from catshark cartilages (Scyliorhi-nus canicula, 20 mg/mL). Cryo-TEM images confirmed the formation of spherical vesicles, while photon correlation spectroscopy analysis disclosed the formation of small and negatively-charged vesicles. PEVs were the smaller vesicles (~100 nm) along with gelatin-hyalurosomes (~120 nm), while chondroitin-PEVs and chondroitin-hyalurosomes were larger (~160 nm). Dispersions prepared with chondroitin sulfate were more homogeneous, as the polydispersity index was ~0.15. The in vitro analysis of the droplet size distribution, average velocity module and spray cone angle suggested a good spray-ability and deposition of formulations in the nasal cavity, as the mean diameter of the droplets was in the range recommended by the Food and Drug Administration for nasal targets. The spray plume analysis confirmed the ability of PEVs, gelatin-PEVs, hyalurosomes and gelatin-hyalurosomes to be atomized in fine droplets homogenously distributed in a full cone plume, with an angle ranging from 25 to 30◦ . Moreover, vesicles were highly biocompatible and capable of protecting the epithelial cells against oxidative damage, thus preventing the inflammatory state
Magnetic fields in M dwarfs from the CARMENES survey
M dwarfs are known to generate the strongest magnetic fields among
main-sequence stars with convective envelopes, but the link between the
magnetic fields and underlying dynamo mechanisms, rotation, and activity still
lacks a consistent picture. In this work we measure magnetic fields from the
high-resolution near-infrared spectra taken with the CARMENES radial-velocity
planet survey in a sample of 29 active M dwarfs and compare our results against
stellar parameters. We use the state-of-the-art radiative transfer code to
measure total magnetic flux densities from the Zeeman broadening of spectral
lines and filling factors. We detect strong kG magnetic fields in all our
targets. In 16 stars the magnetic fields were measured for the first time. Our
measurements are consistent with the magnetic field saturation in stars with
rotation periods P<4d. The analysis of the magnetic filling factors reveal two
different patterns of either very smooth distribution or a more patchy one,
which can be connected to the dynamo state of the stars and/or stellar mass.
Our measurements extend the list of M dwarfs with strong surface magnetic
fields. They also allow us to better constrain the interplay between the
magnetic energy, stellar rotation, and underlying dynamo action. The high
spectral resolution and observations at near-infrared wavelengths are the
beneficial capabilities of the CARMENES instrument that allow us to address
important questions about the stellar magnetism.Comment: 13 pages of main text, 14 pages of online material, 2 table
Comparative study of ornamental granite cleaning using femtosecond and nanosecond pulsed lasers
Granite has been widely used as a structural and ornamental element in public works and buildings. In damp climates it is almost permanently humid and its exterior surfaces are consequently biologically colonized and blackened We describe a comparative analysis of the performance of two different laser sources in removing biological crusts from granite surfaces: nanosecond Nd:YVO4 laser (355 nm) and femtosecond Ti:Sapphire laser at its fundamental wavelength (790 nm) and second harmonic (395 nm). The granite surface was analyzed using scanning electron microscopy, attenuated total reflection – Fourier transform infrared spectroscopy and profilometry, in order to assess the degree of cleaning and to characterize possible morphological and chemical changes caused by the laser sources.This work is supported by the CTM2010-19584, FIS2009-09522 and CSD2007-00013 research projects (Ministerio de Ciencia y Tecnología, Spanish Government) and by SA086A12-2 project (Junta de Castilla y León, Spain). FTIR, profilometry and SEM analyses were conducted at the University of Vigo's research centre (CACTI)
The human Na<sup>+</sup>/H<sup>+</sup> exchanger 1 is a membrane scaffold protein for extracellular signal-regulated kinase 2
Background
Extracellular signal-regulated kinase 2 (ERK2) is an S/T kinase with more than 200 known substrates, and with critical roles in regulation of cell growth and differentiation and currently no membrane proteins have been linked to ERK2 scaffolding.
Methods and results
Here, we identify the human Na+/H+ exchanger 1 (hNHE1) as a membrane scaffold protein for ERK2 and show direct hNHE1-ERK1/2 interaction in cellular contexts. Using nuclear magnetic resonance (NMR) spectroscopy and immunofluorescence analysis we demonstrate that ERK2 scaffolding by hNHE1 occurs by one of three D-domains and by two non-canonical F-sites located in the disordered intracellular tail of hNHE1, mutation of which reduced cellular hNHE1-ERK1/2 co-localization, as well as reduced cellular ERK1/2 activation. Time-resolved NMR spectroscopy revealed that ERK2 phosphorylated the disordered tail of hNHE1 at six sites in vitro, in a distinct temporal order, with the phosphorylation rates at the individual sites being modulated by the docking sites in a distant dependent manner.
Conclusions
This work characterizes a new type of scaffolding complex, which we term a “shuffle complex”, between the disordered hNHE1-tail and ERK2, and provides a molecular mechanism for the important ERK2 scaffolding function of the membrane protein hNHE1, which regulates the phosphorylation of both hNHE1 and ERK2
The magnetically-active, low-mass, triple system WDS 19312+3607
Aims: We investigated in detail the system WDS 19312+3607, whose primary is
an active M4.5Ve star previously thought to be young (tau ~ 300-500 Ma) based
on high X-ray luminosity. Methods: We collected intermediate- and
low-resolution optical spectra taken with 2 m-class telescopes, photometric
data from the to 8 mum bands, and eleven astrometric epochs with a time
baseline of over 56 years for the two components in the system, G 125-15 and G
125-14. Results: We derived M4.5V spectral types for both stars, confirmed
their common proper motion, estimated the heliocentric distance and projected
physical separation, determined the galactocentric space velocities, and
deduced a most-probable age older than 600 Ma. We discovered that the primary,
G 125-15, is in turn an inflated, double-lined, spectroscopic binary with a
short period of photometric variability of P ~ 1.6 d, which we associated to
orbital synchronisation. The observed X-ray and Halpha emissions, photometric
variability, and abnormal radius and effective temperature of G 125-15 AB
indicate strong magnetic activity, possibly due to fast rotation. Besides, the
estimated projected physical separation between G 125-15 AB and G 125-14 of
about 1200 AU makes WDS 19312+3607 to be one of the widest systems with
intermediate M-type primaries. Conclusions: G 125-15 AB is a nearby (d ~ 26
pc), bright (J ~ 9.6 mag), active spectroscopic binary with a single
proper-motion companion of the same spectral type at a wide separation. They
are thus ideal targets for specific follow-ups to investigate wide and close
multiplicity or stellar expansion and surface cooling due to reduced convective
efficiency.Comment: A&A, in pres
Early-type galaxies at large galactocentric radii - I. Stellar kinematics and photometric properties
We present the results of a combined analysis of the kinematic and
photometric properties at large galactocentric radii of a sample of 14
low-luminosity early-type galaxies in the Fornax and Virgo clusters. From
Gemini South GMOS long-slit spectroscopic data we measure radial profiles of
the kinematic parameters v_{rot}, sigma, h_{3}, and h_{4} out to ~ 1 - 3
effective radii. Multi-band imaging data from the HST/ACS are employed to
evaluate surface brightness profiles and isophotal shape parameters of
ellipticity, position angle and discyness/boxiness. The galaxies are found to
host a cold and old stellar component which extend to the largest observed
radii and that is the dominant source of their dynamical support. The
prevalence of discy-shaped isophotes and the radial variation of their
ellipticity are signatures of a gradual gas dissipation. An early star-forming
collapse appears to be the main mechanism acting in the formation of these
objects. Major mergers are unlikely to have occurred in these galaxies. We can
not rule out a minor merging origin for these galaxies, but a comparison of our
results with model predictions of different merger categories places some
constraints on the possible merger progenitors. These merger events are
required to happen at high-redshift (i.e., z > 1), between progenitors of
different mass ratio (at least 3:1) and containing a significant amount of gas
(i.e., > 10 percent). A further scenario is that the low-luminosity galaxies
were originally late-type galaxies, whose star formation has been truncated by
removal of gas and subsequently the disc has been dynamically heated by high
speed encounters in the cluster environment.Comment: 19 pages, 16 figures (Contact author for high resolution version of
figures 1,2,3), MNRAS, accepted. The second paper of the series "Early-type
galaxies at large galactocentric radii - II. Metallicity gradients and the
[Z/H]-mass, [alpha/Fe] mass relations" can be found at arXiv:1006.169
Extraction, characterization and incorporation of Hypericum scruglii extract in ad hoc formulated phospholipid vesicles designed for the treatment of skin diseases connected with oxidative stress
An extract of Hypericum scruglii, an endangered endemic plant of Sardinia (Italy), was prepared and characterized. It was loaded in special phospholipid vesicles, glycerosomes, which were modified by adding maltodextrin (glucidex) and a polymer (gelatin or hyaluronan). The corresponding liposomes were also prepared and used as reference. The vesicles disclosed suitable physicochemical features for skin delivery. Indeed, their mean diameter ranged from 120 to 160 nm, they were homogeneously dispersed (polydispersity index 0.30), and their zeta potential was highly negative (-45 mV). The vesicle dispersions maintained unchanged characteristics during 60 days of storage, were highly biocompatible, and were able to protect keratinocytes against damages due to oxidative stress induced by treating them with hydrogen peroxide. Vesicles were also capable of promoting cell proliferation and migration in vitro by means of a scratch wound assay. The results confirmed the fruitful delivery of the extract of H. scruglii in glycerosomes modified with glucidex and gelatin and their promising ability for skin protection and treatment
The Herschel Virgo Cluster Survey: VII. Dust in cluster dwarf elliptical galaxies
We use the Science Demonstration Phase data of the Herschel Virgo Cluster
Survey to search for dust emission of early-type dwarf galaxies in the central
regions of the Virgo Cluster as an alternative way of identifying the
interstellar medium.We present the first possible far-infrared detection of
cluster early-type dwarf galaxies: VCC781 and VCC951 are detected at the 10
sigma level in the SPIRE 250 micron image. Both detected galaxies have dust
masses of the order of 10^5 Msun and average dust temperatures ~20K. The
detection rate (less than 1%) is quite high compared to the 1.7% detection rate
for Hi emission, considering that dwarfs in the central regions are more Hi
deficient. We conclude that the removal of interstellar dust from dwarf
galaxies resulting from ram pressure stripping, harassment, or tidal effects
must be as efficient as the removal of interstellar gas.Comment: Letter accepted for publication in A&A (Herschel special issue
The low-luminosity galaxy population in the NGC 5044 Group (Conference proceeding)
Detailed surface photometry for 79 (mostly dwarf) galaxies in the NGC 5044
Group area is analysed, revealing the existence of different morphologies among
objects originally classified as early-type dwarfs. Particularly, a significant
fraction of bright dwarf "ellipticals" show a distinct bulge+disc structure; we
thus re-classify these objects as dwarf lenticulars (dS0). Our finding points
at a possible scenario where these systems are the remnants of "harassed" disc
galaxies. This is emphasized by the discovery of a few objects with hints for
very low-surface brightness spiral-like structure. The colours, structure, and
spatial distribution of the different galaxy types suggest that our
classification may indeed be separating objects with different origins and/or
evolutionary paths.Comment: 5 pages. To appear in ESO Astrophysics Symposia: "Groups of Galaxies
in the Nearby Universe
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