3,321 research outputs found
Crystal structure of the heterotrimeric integrin-binding region of laminin-111
Laminins are cell - adhesive glycoproteins that are essential for basement membrane assembly and function. Integrins are important laminin receptors, but their binding site on the heterotrimeric laminin s is poorly defined structurally. We report the crystal structure at 2.13 Å resolution of a minimal integrin - binding fragment of mouse laminin - 111, consisting of ~50 resid ues of α 1 β 1 γ 1 coiled coil and the first three lam inin G - like (LG) domains of the α 1 chain . The LG domains adopt a triangular arrangem ent, with the C - terminus of the coiled coil situated between LG1 and LG2. The critical integrin - binding glutamic acid residue in the γ 1 chain tail is surface - exposed and predicted to bind to the metal ion - dependent adhesion site in the integrin β 1 subunit. Additional contacts to the integrin are likely to be made by the LG1 and LG2 surfaces adjacent to the γ 1 chain tail, which are notably conserved and free of obstructing glycans
Solar Neutrinos: Spin Flavour Precession and LMA
The time dependence that appears to be hinted by the data from the first 13
years of the solar neutrino Gallium experiments is viewed as resulting from a
partial conversion of active neutrinos to light sterile ones through the
resonant interaction between the magnetic moment of the neutrino and a varying
solar field. A summary of the model and its predictions are presented for the
forthcoming experiments Borexino and LENS.Comment: 6 pages, 3 figures, contribution to 12th Lomonosov Conference in
Elementary Particle Physics, Moscow, Aug 24-31 (2005
The outburst of the eruptive young star OO Serpentis between 1995 and 2006
OO Serpentis is a deeply embedded pre-main sequence star that went into
outburst in 1995 and gradually faded afterwards. Its eruption resembled the
well-known FU Orionis-type or EX Lupi-type outbursts. Since very few such
events have ever been documented at infrared wavelengths, our aim is to study
the temporal evolution of OO Ser in the infrared. OO Ser was monitored with the
Infrared Space Observatory starting 4 months after peak brightness and covering
20 months. In 2004-2006 we again observed OO Ser from the ground and
complemented this dataset with archival Spitzer obsevations also from 2004. We
analysed these data with special attention to source confusion and constructed
light curves at 10 different wavelengths as well as spectral energy
distributions. The outburst caused brightening in the whole infrared regime.
According to the infrared light curves, OO Ser started a wavelength-independent
fading after peak brightness. Later the flux decay became slower but stayed
wavelength-independent. The fading is still ongoing, and current fading rates
indicate that OO Ser will not return to quiescent state before 2011. The
outburst timescale of OO Ser seems to be shorter than that of FUors, but longer
than that of EXors. The outburst timescale and the moderate luminosity suggest
that OO Ser is different from both FUors and EXors, and shows similarities to
the recently erupted young star V1647 Ori. Based on its spectral energy
distribution and bolometric temperature, OO Ser seems to be an early class I
object, with an age of < 10^5 yr. The object is probably surrounded by an
accretion disc and a dense envelope. Due to the shorter outburst timescales,
the viscosity in the circumstellar disc of OO Ser is probably an order of
magnitude higher than usual for FUors.Comment: 12 pages, 7 figures, accepted for publication in A&
Low molecular weight ϵ-caprolactone-pcoumaric acid copolymers as potential biomaterials for skin regeneration applications
ϵ-caprolactone-p-coumaric acid copolymers at different mole ratios (ϵ-caprolactone:p-coumaric acid 1:0, 10:1, 8:1, 6:1, 4:1, and 2:1) were synthesized by melt-polycondensation and using 4-dodecylbenzene sulfonic acid as catalyst. Chemical analysis by NMR and GPC showed that copolyesters were formed with decreasing molecular weight as p-coumaric acid content was increased. Physical characteristics, such as thermal and mechanical properties, as well as water uptake and water permeability, depended on the mole fraction of pcoumaric acid. The p-coumarate repetitive units increased the antioxidant capacity of the copolymers, showing antibacterial activity against the common pathogen Escherichia coli. In addition, all the synthesized copolyesters, except the one with the highest concentration of the phenolic acid, were cytocompatible and hemocompatible, thus becoming potentially useful for skin regeneration applications
Diabetic Macular Edema: From Old Concepts to New Therapeutic Avenues
Diabetic macular edema (DME) is an important cause of blindness in the working population and is currently challenging to treat. Current interventions include focal laser or intravitreal injections. This article outlines a new treatment protocol based on the concept that peripheral ischemia is the introduction to angiogenesis, that will ultimately gather its momentum at the fovea. Performing extreme peripheral light laser panretinal photocoagulation (PRP) back to the equator reduces excessive expression of the vascular endothelial growth factor (VEGF) in the eye. Subsequently, this decreases VEGF-induced DME and provides long-term protection for the development of neovascularization. Initial exacerbation of DME often accompanies PRP, Therefore; first injections of anti-VEGF agents (with or without dexamethasone implant) can forestall worsening of DME preventing loss of vision. However, on the other hand, applying peripheral PRP and intraocular injections can induce posterior vitreous detachment (PVD). This could help release vitreomacular adhesions (VMA) and vitreomacular traction (VMT), decreasing DME severity and improving response to intravitreal injections. The current approach works by laser ablation of the peripheral retina that should stop the drive for VEGF release; moreover, laser ablation should produce secondary, accidental and beneficial PVD. This approach precludes focal laser therapy and paves the path for prolonged anti-VEGF therapy
Dispersión de juveniles de Cigüeña Blanca (Ciconia ciconia) en Córdoba (S de España)
D'un total de 91 cigonyes blanques marcades amb anelles de PVC a la província de Córdova entre 1990-1993 sis van ser localitzades com a nidificants a la mateixa àrea entre 1991 i 1994. Altres tres exemplars es van trobar a les províncies veïnes de Sevilla, Huelva i Ciutat Reial. La distància mitjana des del lloc de naixement al de nidificació fou 80,7 km (s.d.=81,8, n=13, distància màxima= 250 km, mínima= 0). Aquests resultats suggereixen que l'augment detectat en les poblacions nidificants de cigonya blanca de Córdova i altres llocs d'Espanya podria estar relacionat amb una baixa mortalitat dels juvenils que retornen a criar prop de les seves àrees de naixement
Forgotten exogenous corticosteroid as a cause of central serous chorioretinopathy
Central serous chorioretinopathy (CSCR) is an idiopathic ocular condition – first described in 1866 – that is well known to ophthalmologists. It is less well known to other practitioners. Glucocorticoids have been strongly implicated as a pathogenic factor. We report three patients who developed CSCR following exogenous administration of corticosteroid. Because our patients did not suspect the use of corticosteroid to be important or causative, they did not volunteer the historical detail, and admitted to exogenous corticosteroid injection only with intensive questioning. For their part, physicians should be cognizant of the risk of corticosteroid-induced CSCR, particularly in patients with a prior history of the potentially sight-threatening disease. The development of CSCR is an important iatrogenic and often unrecognized side effect of exogenously administered corticosteroid
Possible Tomography of the Sun's Magnetic Field with Solar Neutrinos
The data from solar neutrino experiments together with standard solar model
predictions are used in order to derive the possible profile of the magnetic
field inside the Sun, assuming the existence of a sizeable neutrino magnetic
moment and the resonant spin flavour mechanism. The procedure is based on the
relationship between resonance location and the energy dependent neutrino
suppression, so that a large neutrino suppression at a given energy is taken to
be connected to a large magnetic field in a given region of the Sun. In this
way it is found that the solar field must undergo a very sharp increase by a
factor of at least 6 - 7 over a distance no longer than 7 - 10% of the solar
radius, decreasing gradually towards the surface. The range in which this sharp
increase occurs is likely to be the bottom of the convective zone. There are
also indications in favour of the downward slope being stronger at the start
and more moderate on approaching the solar surface. Typical ranges for the
magnetic moment are from a few times 10^{-13}\mu_B to its laboratory upper
bounds while the mass square difference between neutrino flavours is of order
(0.6-1.9) x 10^{-8}eV^2.Comment: Several minor corrections performed, sunspot anticorrelation
discussed, references added, 29 pages including 8 figures in PostScrip
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