Improved performance of LDPC-coded MIMO systems with EP-based soft-decisions

The proceeding at: IEEE International Symposium on Information Theory (ISIT 2014), took place 2014, June 29-July 04, in Honolulu (Hawai)Modern communications systems use efficient encoding schemes, multiple-input multiple-output (MIMO) and high-order QAM constellations for maximizing spectral efficiency. However, as the dimensions of the system grow, the design of efficient and low-complexity MIMO receivers possesses technical challenges. Symbol detection can no longer rely on conventional approaches for posterior probability computation due to complexity. Marginalization of this posterior to obtain per-antenna soft-bit probabilities to be fed to a channel decoder is computationally challenging when realistic signaling is used. In this work, we propose to use Expectation Propagation (EP) algorithm to provide an accurate low-complexity Gaussian approximation to the posterior, easily solving the posterior marginalization problem. EP soft-bit probabilities are used in an LDPC-coded MIMO system, achieving outstanding performance improvement compared to similar approaches in the literature for low-complexity LDPC MIMO decoding.This work has been partly funded by the Spanish Ministry of Science and Innovation with the projects GRE3NSYST (TEC2011-29006-C03-03) and ALCIT (TEC2012-38800-C03-01) and by the program CONSOLIDERINGENIO 2010 under the project COMONSENS (CSD 2008-00010).Publicad

Expectation Propagation Detection for High-Order High-Dimensional MIMO Systems

Modern communications systems use multiple-input multiple-output (MIMO) and high-order QAM constellations for maximizing spectral efficiency. However, as the number of antennas and the order of the constellation grow, the design of efficient and low-complexity MIMO receivers possesses big technical challenges. For example, symbol detection can no longer rely on maximum likelihood detection or sphere-decoding methods, as their complexity increases exponentially with the number of transmitters/receivers. In this paper, we propose a low-complexity high-accuracy MIMO symbol detector based on the Expectation Propagation (EP) algorithm. EP allows approximating iteratively at polynomial-time the posterior distribution of the transmitted symbols. We also show that our EP MIMO detector outperforms classic and state-of-The-Art solutions reducing the symbol error rate at a reduced computational complexity.This work has been partly funded by the Spanish Ministry of Science and Innovation with the projects GRE3NSYST (TEC2011- 29006-C03-03) and ALCIT (TEC2012-38800-C03-01) and by the program CONSOLIDER-INGENIO 2010 under the project COMONSENS (CSD 2008- 00010).Publicad

Effects of a mutation in the gyrA gene on the virulence of uropathogenic Escherichia coli

Fluoroquinolones are among the drugs most extensively used for the treatment of bacterial infections in human and veterinary medicine. Resistance to quinolones can be chromosome or plasmid mediated. The chromosomal mechanism of resistance is associated with mutations in the DNA gyrase- and topoisomerase IV-encoding genes and mutations in regulatory genes affecting different efflux systems, among others. We studied the role of the acquisition of a mutation in the gyrA gene in the virulence and protein expression of uropathogenic Escherichia coli (UPEC). The HC14366M strain carrying a mutation in the gyrA gene (S83L) was found to lose the capacity to cause cystitis and pyelonephritis mainly due to a decrease in the expression of the fimA, papA, papB, and ompA genes. The levels of expression of the fimA, papB, and ompA genes were recovered on complementing the strain with a plasmid containing the gyrA wild-type gene. However, only a slight recovery was observed in the colonization of the bladder in the GyrA complement strain compared to the mutant strain in a murine model of ascending urinary tract infection. In conclusion, a mutation in the gyrA gene of uropathogenic E. coli reduced the virulence of the bacteria, likely in association with the effect of DNA supercoiling on the expression of several virulence factors and proteins, thereby decreasing their capacity to cause cystitis and pyelonephritis

Leishmania spp. epidemiology of canine leishmaniasis in the Yucatan Peninsula

Canine Leishmaniasis is widespread in various Mexican states, where different species of Leishmania have been isolated from dogs. In the present study, we describe the detection of L. braziliensis, L. infantum, and L. mexicana in serum of dogs from the states of Yucatan and Quintana Roo in the Yucatan Peninsula (Mexico). A total of 412 sera were analyzed by ELISA using the total extract of the parasite and the iron superoxide dismutase excreted by different trypanosomatids as antigens. We found the prevalence of L. braziliensis to be 7.52%, L. infantum to be 6.07%, and L. mexicana to be 20.63%, in the dog population studied. The results obtained with ELISA using iron superoxide dismutase as the antigen were confirmed by western blot analysis with its greater sensitivity, and the agreement between the two techniques was very high

Sensitization of retinoids and corticoids to epigenetic drugs in MYC-activated lung cancers by antitumor reprogramming

Components of the SWI/SNF chromatin remodeling complex, including BRG1 (also SMARCA4), are inactivated in cancer. Among other functions, SWI/SNF orchestrates the response to retinoid acid (RA) and glucocorticoids (GC) involving downregulation of MYC. The epigenetic drugs SAHA and azacytidine, as well as RA and GC, are currently being used to treat some malignancies but their therapeutic potential in lung cancer is not well established. Here we aimed to determine the possible therapeutic effects of azacytidine and SAHA (A/S) alone or in combination with GC plus RA (GC/RA) in lung cancers with either BRG1 inactivation or MYC amplification. In vitro, responses to GC/RA treatment were more effective in MYC-amplified cells. These effects were mediated by BRG1 and involved a reprogramming towards prodifferentiation gene expression signatures and downregulation of MYC. In MYC-amplified cells, administration of GC/RA enhanced the cell growth inhibitory effects of A/S which, in turn, accentuated the prodifferentiation features promoted by GC/RA. Finally, these treatments improved overall survival of mice orthotopically implanted with MYC-amplified, but not BRG1-mutant, cells and reduced tumor cell viability and proliferation. We propose that the combination of epigenetic treatments with retinoids and corticoids of MYC-driven lung tumors constitute a strategy for therapeutic intervention in this otherwise incurable disease

A Gene-alteration Profile of Human Lung Cancer Cell Lines

Aberrant proteins encoded from genes altered in tumors drive cancer development and may also be therapeutic targets. Here we derived a comprehensive gene-alteration profile of lung cancer cell lines. We tested 17 genes in a panel of 88 lung cancer cell lines and found the rates of alteration to be higher than previously thought. Nearly all cells feature inactivation at TP53 and CDKN2A or RB1, whereas BRAF, MET, ERBB2, and NRAS alterations were infrequent. A preferential accumulation of alterations an-tong histopathological types and a mutually exclusive occurrence of alterations of CDKN2A and RB1 as well as of KRAS, epidermal growth factor receptor (EGFR), NRAS, and ERBB2 were seen. Moreover, in non-small-cell lung cancer (NSCLC), concomitant activation of signal transduction pathways known to converge in mammalian target of rapamycin (mTOR) was common. Cells with single activation of ERBB2, PTEN, or MET signaling showed greater sensitivity to cell growth inhibition induced by erlotinib, LY294002, and PHA665752, respectively, than did cells featuring simultaneous activation of these pathways, underlining the need for combined therapeutic strategies in targeted cancer treatments. In conclusion, our gene,alteration landscape of lung cancer cell lines provides insights into how gene alterations accumulate and biological pathways interact in cancer. Hum Mutat 30, 1199-1206, 2009. (C) 2009 Wiley-Liss, Inc

Amifostina. Un tratamiento alternativo contra el cáncer.

La Amifostina [ácido S-2-(3-aminopropilamino) etiolfósforotioico)], prodroga que al desfosforilarse por la fosfatasa alcalina produce el WR1065 [2-(3_aminopropilamino) etanotiol], actúa como atrapador de radicales libres (RL). Su empleo frente al cisplatino, agente que genera RL durante su acción, podría disminuir el daño a las células normales que captan selectivamente la prodroga. Se evaluó la capacidad de la amifostina a diferentes dosis sobre la peroxidación lipídica (TBARS) y la actividad de las enzimas antioxidantes superóxido dismutasa (SOD) y catalasa (CAT) en el tejido renal. Las dosis más efectivas fueron las más bajas, con las que se obtienen la menor concentración de TBARS y la menor actividad SOD y CAT. El modelo es una propuesta para evaluar el efecto citoprotector de la amifostina desde el nivel molecular al tisular.  Palabras clave: Amifostina, peroxidación lipídica; superóxido dismutasa; catalasa

CXCR4+-targeted protein nanoparticles produced in the food-grade bacterium Lactococcus lactis

Altres ajuts: CIBER de Bioingeniería, Biomateriales y Nanomedicina (project NANOPROTHER). A Villaverde received an ICREA ACADEMIA award. OC Garrido received a PhD fellowship from MECD and EGF a postdoctoral fellowship from INIA (DOC-INIA, INIA, MINECO). Unzueta received a Sara Borrell postdoctoral fellowship from ISCIII.Aim: Lactococcus lactis is a Gram-positive (endotoxin-free) food-grade bacteria exploited as alternative to Escherichia coli for recombinant protein production. We have explored here for the first time the ability of this platform as producer of complex, self-assembling protein materials. Materials & methods: Biophysical properties, cell penetrability and in vivo biodistribution upon systemic administration of tumor-targeted protein nanoparticles produced in L. lactis have been compared with the equivalent material produced in E. coli. Results: Protein nanoparticles have been efficiently produced in L. lactis, showing the desired size, internalization properties and biodistribution. Conclusion: In vitro and in vivo data confirm the potential and robustness of the production platform, pointing out L. lactis as a fascinating cell factory for the biofabrication of protein materials intended for therapeutic applications

Optimización estadística de un bioproceso de ácido láctico a partir de lactosuero

The use of industrial waste as a substrate is a worldwide trend, whey is one of them. The objective of the research was to find the combination of temperature and pH that maximizes the productivity of lactic acid with the use of whey and Lactobacillus casei. The temperature variables were evaluated in the values ​​of (29, 31.1, 37, 42.7 and 45 °C) and pH (4.8, 5, 5.5, 6 and 6.2) to find optimal parameters of the bioprocess that maximize the volumetric productivity of lactic acid. by using the Central Composite Design using the Design Expert 11.0 program. Thirteen runs were carried out. The validity of the quadratic model was verified through 3 repetitions with the optimal parameters suggested by the program, and it was determined that the conditions for maximizing volumetric productivity are 40.2 °C of temperature and 5.6 of pH, reaching values ​​of 1.2 g. l-1h-1 and it was confirmed that there is no significant difference (p ≤ 0.05) with the values ​​provided by the model. Concluding that the optimal values ​​of temperature and pH found were close to those reported by other authors and it was shown that whey has great potential to be used as a substrate.El uso de residuales de la industria como sustrato es tendencia a nivel mundial, el lactosuero es uno de ellos. El objetivo de la investigación fue encontrar la combinación de temperatura y pH que maximicen la productividad de ácido láctico con el uso de lactosuero y Lactobacillus casei. Se evaluaron las variables de temperatura en los valores de (29, 31.1, 37, 42.7 y 45 °C) y pH (4.8, 5, 5.5, 6 y 6.2) para encontrar parámetros óptimos del bioproceso que maximicen la productividad volumétrica de ácido láctico mediante el uso del Diseño Central Compuesto utilizando el programa Design Expert 11.0. Se realizaron trece corridas. Se verificó la validez del modelo cuadrático mediante 3 repeticiones con los parámetros óptimos sugeridos por el programa y se determinó que las condiciones de maximización de la productividad volumétrica son 40.2 °C de temperatura y 5.6 de pH, alcanzando valores de 1.2 gl-1h-1 y se confirmó que no existe diferencia significativa (p ≤ 0.05) con los valores brindados por el modelo. Concluyendo que los valores óptimos de temperatura y pH encontrados fueron cercanos a los reportados por otros autores y se demostró que el lactosuero tiene un gran potencial para ser utilizado como sustrato