Ana Fragoso

Ultrasound molecular imaging of E-selectin in tumor vessels using poly n-butyl cyanoacrylate microbubbles covalently coupled to a short targeting peptide.

ObjectivesThe purposes of this study were the development and preclinical evaluation of clinically translatable E-selectin–specific ultrasound contrast agents based on a peptide ligand with the recognition sequence IELLQAR. Materials and MethodsThe E-selectin–specific peptide was synthesized through solid phase peptide synthesis and covalently attached to poly n-butylcyanoacrylate–stabilized microbubbles with an air core. Quantification of the microbubble surface coverage with peptides was performed through flow cytometry. Targeted adhesion of peptide-coated microbubbles was investigated in vitro using parallel plate flow chamber assays on tumor necrosis factor-&agr;–stimulated human umbilical vein endothelial cells. In vivo imaging was performed in nude mice bearing human ovarian carcinoma xenografts (MLS), followed by ex vivo immunohistochemistry validation of E-selectin expression. ResultsSuccess of peptide synthesis was validated through preparative reverse phase high-pressure liquid chromatography and electronspray ionization-mass spectrometry. Results of the flow cytometry revealed approximately 4000 E-selectin–specific peptides/microbubble surface. Results of the in vitro experiments demonstrated the specificity of peptide-coated microbubbles to E-selectin (1.10 ± 0.48 vs 0.19 ± 0.09 bound microbubbles per cell, before and after competition respectively; P < 0.01). The in vivo imaging enabled specific assessment of E-selectin expression in MLS carcinoma xenografts (5.21 ± 3.41 vs 1.37 ± 0.67 contrast intensity before and after competition, respectively; P < 0.05). ConclusionsClinically translatable microbubbles that were covalently coupled to the short E-selectin–specific peptide (IELLQAR) enabled specific imaging of the E-selectin expression in tumor vessels in vivo.

Harnessing the Flexibility of Peptidic Scaffolds to Control their Copper(II)‐Coordination Properties: A Potentiometric and Spectroscopic Study

Designing small peptides that are capable of binding Cu(2+) ions mainly through the side-chain functionalities is a hard task because the amide nitrogen atoms strongly compete for Cu(2+) ion coordination. However, the design of such peptides is important for obtaining biomimetic small systems of metalloenyzmes as well as for the development of artificial systems. With this in mind, a cyclic decapeptide, C-Asp, which contained three His residues and one Asp residue, and its linear derivative, O-Asp, were synthesized. The C-Asp peptide has two Pro-Gly β-turn-inducer units and, as a result of cyclization, and as shown by CD spectroscopy, its backbone is constrained into a more defined conformation than O-Asp, which is linear and contains a single Pro-Gly unit. A detailed potentiometric, mass spectrometric, and spectroscopic study (UV/Vis, CD, and EPR spectroscopy) showed that at a 1:1 Cu(2+)/peptide ratio, both peptides formed a major [CuHL](2+) species in the pH range 5.0-7.5 (C-Asp) and 5.5-7.0 (O-Asp). The corrected stability constants of the protonated species (log K*(CuH(O-Asp))=9.28 and log K*(CuH(C-Asp))=10.79) indicate that the cyclic peptide binds Cu(2+) ions with higher affinity. In addition, the calculated value of K(eff) shows that this higher affinity for Cu(2+) ions prevails at all pH values, not only for a 1:1 ratio but even for a 2:1 ratio. The spectroscopic data of both [CuHL](2+) species are consistent with the exclusive coordination of Cu(2+) ions by the side-chain functionalities of the three His residues and the Asp residue in a square-planar or square-pyramidal geometry. Nonetheless, although these data show that, upon metal coordination, both peptides adopt a similar fold, the larger conformational constraints that are present in the cyclic scaffold results in different behaviour for both [CuHL](2+) species. CD and NMR analysis revealed the formation of a more rigid structure and a slower Cu(2+)-exchange rate for [CuH(C-Asp)](2+) compared to [CuH(O-Asp](2+). This detailed comparative study shows that cyclization has a remarkable effect on the Cu(2+)-coordination properties of the C-Asp peptide, which binds Cu(2+) ions with higher affinity at all pH values, stabilizes the [CuHL](2+) species in a wider pH range, and has a slower Cu(2+)-exchange rate compared to O-Asp.

EMIR: the GTC NIR multi-object imager-spectrograph

In this contribution we review the overall features of EMIR, the NIR multiobject spectrograph of the GTC. EMIR is at present in the middle of the PD phase and will be one of the first common user instruments for the GTC, the 10 meter telescope under construction by GRANTECAN at the Roque de los Muchachos Observatory (Canary Islands, Spain). EMIR is being built by a Consortium of Spanish, French and British institutes led by the IAC. EMIR is designed to realize one of the central goals of 10m class telescopes, allowing observers to obtain spectra for large numbers of faint sources in an time-efficient manner. EMIR is primarily designed to be operated as a MOS in the K band, but offers a wide range of observing modes, including imaging and spectroscopy, both long slit and multiobject, in the wavelength range 0.9 to 2.5 μm. The present status of development, expected performances and schedule are described and discussed. This project is funded by GRANTECAN and the Plan Nacional de Astronomía y Astrofísica (National Plan for Astronomy and Astrophysics, Spain).

HARMONI: a single-field wide-band integral-field spectrograph for the European ELT

We describe the results of a Phase A study for a single field, wide band, near-infrared integral field spectrograph for the European Extremely Large Telescope (E-ELT). HARMONI, the High Angular Resolution Monolithic Optical & Nearinfrared Integral field spectrograph, provides the E-ELTs core spectroscopic requirement. It is a work-horse instrument, with four different spatial scales, ranging from seeing to diffraction-limited, and spectral resolving powers of 4000, 10000 & 20000 covering the 0.47 to 2.45 μm wavelength range. It is optimally suited to carry out a wide range of observing programs, focusing on detailed, spatially resolved studies of extended objects to unravel their morphology, kinematics and chemical composition, whilst also enabling ultra-sensitive observations of point sources. We present a synopsis of the key science cases motivating the instrument, the top level specifications, a description of the opto-mechanical concept, operation and calibration plan, and image quality and throughput budgets. Issues of expected performance, complementarity and synergies, as well as simulated observations are presented elsewhere in these proceedings[1].

OSIRIS tunable imager and spectrograph for the GTC: from design to commissioning

OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) was the optical Day One instrument for the 10.4m Spanish telescope GTC. It is installed at the Observatorio del Roque de Los Muchachos (La Palma, Spain). This instrument has been operational since March-2009 and covers from 360 to 1000 nm. OSIRIS observing modes include direct imaging with tunable and conventional filters, long slit and low resolution spectroscopy. OSIRIS wide field of view and high efficiency provide a powerful tool for the scientific exploitation of GTC. OSIRIS was developed by a Consortium formed by the Instituto de Astrofísica de Canarias (IAC) and the Instituto de Astronomía de la Universidad Nacional Autónoma de México (IA-UNAM). The latter was in charge of the optical design, the manufacture of the camera and collaboration in the assembly, integration and verification process. The IAC was responsible for the remaining design of the instrument and it was the project leader. The present paper considers the development of the instrument from its design to its present situation in which is in used by the scientific community.

EMIR: THE GTC NIR MULTI-OBJECT IMAGER-SPECTROGRAPH

no nal global y el desempe~ de EMIR, el espectr ografo para objetos m ultiples del NIR del GTC, como tambi en el plan para su aplicaci on cient ca inicial. EMIR, actualmente en sus fases nales, ser a uno de los primeros instrumentos para usuarios del GTC, el telescopio de 10 metros en construcci on por GRANTECAN en el Observatorio del Roque de los Muchachos (Islas Canarias, Espa~ A EMIR lo construye un consorcio de institutos espa~ y franceses conducido por IAC. EMIR est a dise~ para llevar a cabo uno de los objetivos centrales de los telescopios de la clase de 10 metros, lo que permitir a a los observadores obtener espectros de gran n umero de objetos d ebiles de una manera ecien te en cuanto al tiempo. EMIR est a dise~ para ser operado primariamente como un MOS en la banda K, pero ofrece adem as un amplio rango de modos observacionales, incluido imagen y espectroscop a, tanto de rendija larga como de objetos m ultiples, en el rango de longitudes de onda de 0.9 a 2.5 m. Se encuentra equipado con dos subsistemas novedosos: una m ascara de rendijas m ultiples rob otica recongurable y elementos dispersivos formados por una combinaci on de rejilla de difracci on y prismas convencionales de alta calidad, ambos localizados en el coraz on del instrumento. Se describe y discute el estado actual de desarrollo, el desempe~ esperado, el calendario y los planes de aplicaci on cient ca. Este proyecto est a nanciado mayormente por GRANTECAN y el Plan Nacional de Astronom a y Astrof sica de Espa~ na.

Design of the opto-mechanical mounts of the ESPRESSO spectograph

ESPRESSO is the next generation European exoplanet hunter, combining the efficiency of a modern echelle spectrograph with extreme radial velocity and spectroscopic precision. The instrumental radial velocity precision will be improved to reach 10 cm/s level, to achieve a gain of two magnitudes with respect to its predecessor HARPS. The fiber-fed, non-rotating instrument will be installed in the Combined Coudé Laboratory of the VLT (Very Large Telescope), which is situated in the Paranal Observatory (Chile). The main challenge in the design of the optical mounts of the instrument has been the extreme long-term stability of big rectangular optical components in a seismic environment. This paper describes the requirements and the adopted solution for the opto-mechanical design of the collimator mirrors, dichroic lens, field lens and cross dispersers of the instrument.

Test results: EMIR optomechanics

EMIR is a NIR multiobject spectrograph with imaging capabilities to be used at the GTC. The first collimator lens in EMIR, made of Fused Silica, has an outer diameter of 490 mm, and a weight of 265 N, which make it one of the largest Fused Silica lenses ever mounted to work under cryogenic conditions. The results of the various tests being done at the IAC (with two different lens dummies) in order to validate a mounting design concept for this lens, are presented here. The radial support concept tested consists of three contact areas around the lens, one of which is a PTFE block, preloaded by coil springs and the other two are fixed supports made of Aluminum and PTFE, dimensioned in order to keep lens centered both at room temperature and under operation conditions.