GLUT1 protects prostate cancer cells from glucose deprivation-induced oxidative stress

Glucose, chief metabolic support for cancer cell survival and growth, is mainly imported into cells by facilitated glucose transporters (GLUTs). The increase in glucose uptake along with tumor progression is due to an increment of facilitative glucose transporters as GLUT1. GLUT1 prevents cell death of cancer cells caused by growth factors deprivation, but there is scarce information about its role on the damage caused by glucose deprivation, which usually occurs within the core of a growing tumor. In prostate cancer (PCa), GLUT1 is found in the most aggressive tumors, and it is regulated by androgens. To study the response of androgen-sensitive and insensitive PCa cells to glucose deprivation and the role of GLUT1 on survival mechanisms, androgen-sensitive LNCaP and castration-resistant LNCaP-R cells were employed. Results demonstrated that glucose deprivation induced a necrotic type of cell death which is prevented by antioxidants. Androgen-sensitive cells show a higher resistance to cell death triggered by glucose deprivation than castration-resistant cells. Glucose removal causes an increment of H2O2, an activation of androgen receptor (AR) and a stimulation of AMP-activated protein kinase activity. In addition, glucose removal increases GLUT1 production in androgen sensitive PCa cells. GLUT1 ectopic overexpression makes PCa cells more resistant to glucose deprivation and oxidative stress-induced cell death. Under glucose deprivation, GLUT1 overexpressing PCa cells sustains mitochondrial SOD2 activity, compromised after glucose removal, and significantly increases reduced glutathione (GSH). In conclusion, androgen-sensitive PCa cells are more resistant to glucose deprivation-induced cell death by a GLUT1 upregulation through an enhancement of reduced glutathione levels. Keywords: Glut1, Prostate cancer, Glucose deprivation, Androgen receptor, Glutathione, Oxidative stres

Formation and emission properties of single InGaAs/GaAs quantum dots and pairs grown by droplet epitaxy

Trabajo presentado a la 30th International Conference on the Physics of Semiconductors, celebrada en Seul (Korea) del 25 al 30 de Julio de 2010.The emission properties of lateral and vertical QD pairs grown on GaAs nanoholes are investigated. Vertical QD pairs with different size asymmetry have been fabricated controlling the bottom QD size independently of the areal density. The emission of individual pairs is dominated by spectral diffusion effects and charge instabilities induced by the local charge environment. Lateral QD pairs have been fabricated on GaAs nanoholes and studied as a function of an electric field applied in the growth plane.Peer Reviewe

Impact of CD68/(CD3+CD20) Ratio at the Invasive Front of Primary Tumors on Distant Metastasis Development in Breast Cancer

Tumors are infiltrated by macrophages, T and B-lymphocytes, which may favor tumor development by promoting angiogenesis, growth and invasion. The aim of this study was to investigate the clinical relevance of the relative amount of macrophages (CD68⁺), T-cells (CD3⁺ and B-cells (CD20⁺) at the invasive front of breast carcinomas, and the expression of matrix metalloproteases (MMPs) and their inhibitors (TIMPs) either at the invasive front or at the tumor center. We performed an immunohistochemical study counting CD3, CD20 and CD68 positive cells at the invasive front, in 102 breast carcinomas. Also, tissue sections were stained with MMP-2, -9, -11, -14 and TIMP-2 antibodies, and immunoreactivity location, percentage of reactive area and intensity were determined at the invasive front and at the tumor center. The results showed that an increased CD68 count and CD68/(CD3+CD20) ratio were directly associated with both MMP-11 and TIMP-2 expression by mononuclear inflammatory cells at the tumor center (p = 0.041 and p = 0.025 for CD68 count and p = 0.001 and p = 0.045 for ratio, respectively for MMP-11 and TIMP-2). In addition, a high CD68/(CD3+CD20) ratio (>0.05) was directly associated with a higher probability of shortened relapse-free survival. Multivariate analysis revealed that CD68/(CD3+CD20) ratio was an independent factor associated with distant relapse-free survival (RR: 2.54, CI: (1.23-5.24), p<0.01). Therefore, CD68/(CD3+CD20) ratio at the invasive front could be used as an important prognostic marker

Effects of Gold Induced Crystallization on the thermoelectric properties of Si0.8Ge0.2 thin films grown by sputtering

Póster presentado en la 12th European Conference on Thermoelectrics (ECT2014), celebrada en Madrid del 24 al 26 de septiembre de 2014.Si1-XGeX alloys are widely known thermoelectric materials showing a very high figure of merit at high temperatures, and have been used for long time in different applications. The control of the crystal structure of the material has been demonstrated as a key point on the thermoelectric properties. Sputtering deposition of Si1-XGeX at room temperature gives rise to amorphous material, with very low electric conductivity and hence bad thermoelectric properties. In order to produce crystalline thin films, sputter deposition at high temperature is usually performed, but the high temperatures needed can produce a reduction of the dopant concentration, hence reducing the electric conductivity. Crystallization of amorphous SiGe (a-SiGe) is performed by heating at temperatures over 625ºC during 24 h or more. However, it was shown that metal-induced crystallization (MIC) is a promising technology for reducing crystallization temperature of a-Si, a-Ge and a-SiGe. There are many metals, such as Al, Au, Ag and Ni, that can be used for performing MIC. In spite of the low crystallization temperatures in the above processes of MIC, there were serious problems of metal contamination of the SiGe films. In this paper, we report our works concerning crystallization of Si0.8Ge0.2 thin films using Au as crystallization catalyzer. We selected Au thin film since the eutectic temperatures for Au-Si (363 ºC) and Au-Ge systems (361 ºC) are very close. Post-deposition thermal treatments in inert atmosphere show that crystallization temperature is reduced to about 350 ºC, whit treatment times as short as 1 hour. Moreover, in situ crystallization during the deposition of SiGe over gold is also demonstrated at temperatures over 350 ºC. It shall also be noted that gold acts as a crystallization catalyzer, and can be easily eliminated by chemical methods, as it does not incorporate into the material structure. The crystallized thin films show high Seebeck coefficient and low electric resistance.Peer Reviewe

Parallel nanogap fabrication with nanometer size control using III–V semiconductor epitaxial technology

A nanogap fabrication process using strained epitaxial III–V beams is reported. The process is highly reproducible, allowing parallel fabrication and nanogap size control. The beams are fabricated from MBE-grown (GaAs/GaP)/AlGaAs strained heterostructures, standard e-beam lithography and wet etching. During the wet etching process, the relaxation of the accumulated stress at the epitaxial heterostructure produces a controlled beam breakage at the previously defined beam notch. After the breakage, the relaxed strain is proportional to the beam length, allowing nanogap size control. The starting structure is similar to a mechanically adjustable break junction but the stress causing the breakage is, in this case, built into the beam. This novel technique should be useful for molecular-scale electronic devices.The author IFM would like to thank MEC for the FPI financial support. J.P.Silveira and J.L.Costa-Krämer are gratefully acknowledged for the fruitful discussions and the stimulating support.Peer reviewe

Emission properties of single InAs/GaAs quantum dot pairs and molecules grown in GaAs nanoholes

Trabajo presentado en la International Conference on the physics of semiconductors, celebrado en Seúl (República de Corea), del 25 al 30 de julio de 2010We have studied the lateral coupling between InAs/GaAs quantum dot pairs embedded in a field-effect structure. Quantum dot pairs and molecules have been identified by the correlated evolution of the Coulomb blockade features of each QD in the pair. This behaviour is largely distorted in the presence of resonant coupling states in the QD molecule. Single QD voltage evolution shows a crossover in the lineshape profile, which is associated to Spectral Diffusion processes due to residual charged environment

Emission properties of single InAs/GaAs quantum dot pairs and molecules grown in GaAs nanoholes

Trabajo presentado a la "11th International Conference on Optics of Excitons in Confined Systems" (OECS), celebrada en en Madrid (España) del 7 al 11 de Septiembre de 2009.We have studied the lateral coupling between InAs/GaAs quantum dot pairs embedded in a field-effect structure. Quantum dot pairs and molecules have been identified by the correlated evolution of the Coulomb blockade features of each QD in the pair. This behaviour is largely distorted in the presence of resonant coupling states in the QD molecule. Single QD voltage evolution shows a crossover in the lineshape profile, which is associated to Spectral Diffusion processes due to residual charged environment.The authors gratefully acknowledge financial support by Spanish Ministry of Science and Innovation through grants NANINPHO-QD (TEC-2008-06756-C03-01/03) and Consolider-Ingenio 2010 QOIT(CSD2006-0019) and CAM (S-505/ESP/000200).Peer reviewe

Nitrided FeB amorphous thin films for magneto mechanical systems

8 páginas, 7 figuras, 1 tabla.The structural, magnetic and magnetoelastic properties of Fe–B–N amorphous films, sputtered from a Fe80B20 target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An 20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate (8%) nitrogen content when compared to those for pure Fe80B20 amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices.Three of the authors MSMG, RGA and IFM acknowledge the MEC and CSIC for the Ramon y Cajal for the Juan de la Cierva and for the FPI financial support, respectively.Peer reviewe

Thickness dependence of critical temperature in Mo/Au bilayers

Trabajo presentado a la: "European Conference on Applied Superconductivity (EUCAS)" celebrada del 18 al 23 de septiembre de 2011 en Holanda.We report on the sensitivity of the superconducting critical temperature (TC) to layer thickness, as well as on TC reproducibility in Mo/Au bilayers. Resistivity measurements on samples with a fixed Au thickness (dAu) and Mo thickness (dMo) ranging from 50 to 250 nm, and with a fixed dMo and different dAu thickness are shown. Experimental data are discussed in the framework of Martinis model, whose application to samples with dAu above their coherence length is analysed in detail. Results show a good coupling between normal and superconducting layers and excellent TC reproducibility, allowing to accurately correlate Mo layer thickness and bilayer TC.This work has been carried out with financial support from the Spanish MICINN (projects ESP2006‐13608‐C02, AYA2008‐00591/ESP, MAT2008‐01077/NAN and MAT2009‐13977C03). MPB and OG would like to thank Spanish Education Ministry for a FPU grant and a FPI grant.Peer Reviewe

Effects of Stress and Morphology on the Resistivity and Critical Temperature of Room-Temperature-Sputtered Mo Thin Films

We report on the structural and electrical characterization of Mo thin films deposited at room temperature by RF magnetron sputtering. The effect of RF power on the morphology and residual stress of the films is analyzed. The films are under compressive stress and consist of densely packed columns with a lateral size on the order of 20 nm. The stress, critical temperature, and resistivity of the films are found to rise when increasing the ejected ion energy during the sputtering process. The changes in critical temperature and resistivity are discussed in terms of the observed morphology and stress changes.R. González-Arrabal and J. Sesé would like to thank MEC for their Juan de la Cierva and Ramon y Cajal contracts, respectively. O. Gil and M. Parra-Borderías would like to thank MCINN for their fellowship.Peer reviewe