400 research outputs found
¿Existe relacion entre los parametros de composicion corporal y el riesgo de infección peritoneal (IP) en dialisis peritoneal (DP)?: estudio longitudinal
Resumen de comunicación ora
The diagnostic value of pleural fluid homocysteine in malignant pleural effusion
Background
Pleural fluid homocysteine (HCY) can be useful for diagnosis of malignant pleural effusion (MPE). There are no published studies comparing the diagnostic accuracy of HCY with other tumour markers in pleural fluid for diagnosis of MPE. The aim was to compare the accuracy of HCY with that of carcinoembryonic antigen (CEA), cancer antigen (CA) 15.3, CA19.9 and CA125 in pleural fluid and to develop a probabilistic model using these biomarkers to differentiate benign (BPE) from MPE.
Methods
Patients with pleural effusion were randomly included. HCY, CEA, CA15.3, CEA19.9 and CA125 were quantified in pleural fluid. Patients were classified into two groups: MPE or BPE. By applying logistic regression analysis, a multivariate probabilistic model was developed using pleural fluid biomarkers. The diagnostic accuracy was determined by receiver operating characteristic (ROC) curves and calculating the area under the curve (AUC).
Results
Population of study comprised 133 patients (72 males and 61 females) aged between 1 and 96 years (median = 70 years), 81 BPE and 52 MPE. The logistic regression analysis included HCY (p< 0.0001) and CEA (p = 0.0022) in the probabilistic model and excluded the other tumour markers. The probabilistic model was: HCY+CEA = Probability(%) = 100x( 1 +e(-z))(-1), where Z = 0.5471x[ HCY]+0.3846x[ CEA]-8.2671. The AUCs were 0.606, 0.703, 0.778, 0.800, 0.846 and 0.948 for CA125, CA19.9, CEA, CA15.3, HCY and HCY+CEA, respectively.
Conclusions
Pleural fluid HCY has higher accuracy for diagnosis of MPE than CEA, CA15.3, CA19.9 and CA125. The combination of HCY and CEA concentrations in pleural fluid significantly improves the diagnostic accuracy of the test
Galaxy classification: deep learning on the OTELO and COSMOS databases
Context. The accurate classification of hundreds of thousands of galaxies
observed in modern deep surveys is imperative if we want to understand the
universe and its evolution. Aims. Here, we report the use of machine learning
techniques to classify early- and late-type galaxies in the OTELO and COSMOS
databases using optical and infrared photometry and available shape parameters:
either the Sersic index or the concentration index. Methods. We used three
classification methods for the OTELO database: 1) u-r color separation , 2)
linear discriminant analysis using u-r and a shape parameter classification,
and 3) a deep neural network using the r magnitude, several colors, and a shape
parameter. We analyzed the performance of each method by sample bootstrapping
and tested the performance of our neural network architecture using COSMOS
data. Results. The accuracy achieved by the deep neural network is greater than
that of the other classification methods, and it can also operate with missing
data. Our neural network architecture is able to classify both OTELO and COSMOS
datasets regardless of small differences in the photometric bands used in each
catalog. Conclusions. In this study we show that the use of deep neural
networks is a robust method to mine the cataloged dataComment: 20 pages, 10 tables, 14 figures, Astronomy and Astrophysics (in
press
Molecular epidemiology of enterovirus 71, coxsackievirus A16 and A6 associated with hand, foot and mouth disease in Spain
Producción CientíficaHand, foot and mouth disease (HFMD) is a childhood illness frequently caused by genotypes belonging to the enterovirus A species,
including coxsackievirus (CV)-A16 and enterovirus (EV)-71. Between 2010 and 2012, several outbreaks and sporadic cases of HFMD
occurred in different regions of Spain. The objective of the present study was to describe the enterovirus epidemiology associated with
HFMD in the country. A total of 80 patients with HFMD or atypical rash were included. Detection and typing of the enteroviruses were
performed directly in clinical samples using molecular methods. Enteroviruses were detected in 53 of the patients (66%). CV-A6 was the
most frequent genotype, followed by CV-A16 and EV-71, but other minority types were also identified. Interestingly, during almost all of
2010, CV-A16 was the only causative agent of HFMD but by the end of the year and during 2011, CV-A6 became predominant, while
CV-A16 was not detected. In 2012, however, both CV-A6 and CV-A16 circulated. EV-71 was associated with HFMD symptoms only in
three cases during 2012. All Spanish CV-A6 sequences segregated into one major genetic cluster together with other European and Asian
strains isolated between 2008 and 2011, most forming a particular clade. Spanish EV-71 strains belonged to subgenogroup C2, as did most of
the European sequences circulated. In conclusion, the recent increase of HFMD cases in Spain and other European countries has been due
to a larger incidence of circulating species A enteroviruses, mainly CV-A6 and CV-A16, and the emergence of new genetic variants of these
viruses
How allosteric control of Staphylococcus aureus penicillin binding protein 2a enables methicillin resistance and physiological function
6 pags, 4 figs, 1 tabThe expression of penicillin binding protein 2a (PBP2a) is the basis for the broad clinical resistance to the β-lactam antibiotics by methicillin-resistant Staphylococcus aureus (MRSA). The highmolecular mass penicillin binding proteins of bacteria catalyze in separate domains the transglycosylase and transpeptidase activities required for the biosynthesis of the peptidoglycan polymer that comprises the bacterial cell wall. In bacteria susceptible to β-lactam antibiotics, the transpeptidase activity of their penicillin binding proteins (PBPs) is lost as a result of irreversible acylation of an active site serine by the β-lactam antibiotics. In contrast, the PBP2a of MRSA is resistant to β-lactam acylation and successfully catalyzes the DD-transpeptidation reaction necessary to complete the cell wall. The inability to contain MRSA infection with β-lactam antibiotics is a continuing public health concern. We report herein the identification of an allosteric binding domain - a remarkable 60 Å distant from the DD-transpeptidase active site - discovered by crystallographic analysis of a soluble construct of PBP2a. When this allosteric site is occupied, a multiresidue conformational change culminates in the opening of the active site to permit substrate entry. This same crystallographic analysis also reveals the identity of three allosteric ligands: muramic acid (a saccharide component of the peptidoglycan), the cell wall peptidoglycan, and ceftaroline, a recently approved anti-MRSA β-lactam antibiotic. The ability of an anti-MRSA β-lactam antibiotic to stimulate allosteric opening of the active site, thus predisposing PBP2a to inactivation by a second β-lactam molecule, opens an unprecedented realm for β-lactam antibiotic structure-based design.Work in the United States was supported by National Institutes of Health Grants AI090818 and AI104987, and work in Spain was supported by Grants BFU2011-25326 (from the Spanish Ministry of Economy and Competitiveness) and S2010/BMD-2457 (from the Autonomous Government of Madrid)
Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rhombus tilings
The degree of randomness, or partial order, present in two-dimensional
supramolecular arrays of isophthalate tetracarboxylic acids is shown to vary
due to subtle chemical changes such as the choice of solvent or small
differences in molecular dimensions. This variation may be quantified using an
order parameter and reveals a novel phase behaviour including random tiling
with varying critical properties as well as ordered phases dominated by either
parallel or non-parallel alignment of neighbouring molecules, consistent with
long-standing theoretical studies. The balance between order and randomness is
driven by small differences in the intermolecular interaction energies, which
we show, using numerical simulations, can be related to the measured order
parameter. Significant variations occur even when the energy difference is much
less than the thermal energy highlighting the delicate balance between entropic
and energetic effects in complex self-assembly processes
On-Surface Driven Formal Michael Addition Produces m-Polyaniline Oligomers on Pt(111)
On-surface synthesis is emerging as a highly rational bottom-up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta-polyaniline, a known ferromagnetic polymer, were synthesized from para-aminophenol building-blocks via an unexpected and highly specific on-surface formal 1, 4 Michael-type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in situ scanning tunneling and non-contact atomic force microscopies, high-resolution synchrotron-based X-ray photoemission spectroscopy and first-principles calculations. This study demonstrates the capability of surfaces to selectively modify local molecular conditions to redirect well-established synthetic routes, such as Michael coupling, towards the rational synthesis of new covalent nanostructures
Determination of diquat by flow injection-chemiluminescence
A simple, economic, sensitive and rapid method for the determination of the pesticide diquat was described. This new method was based on the coupling of flow injection analysis methodology and direct chemiluminescent detection; to the authors' knowledge, this approach had not been used up to now with this pesticide. It was based on its oxidation with ferricyanide in alkaline medium; significant improvements in the analytical signal were achieved by using high temperatures and quinine as sensitiser. Its high throughput (144 h(-1)), together with its low limit of detection (2 ng mL(-1)), achieved without need of preconcentration steps, permitted the reliable quantification of diquat over the linear range of (0.01-0.6) mu g mL(-1) in samples from different origins (river, tap, mineral and ground waters), even in the presence of a 40-fold concentration of paraquat, a pesticide commonly present in the commercial formulations of diquat.López-Paz, JL.; Catalá-Icardo, M.; Antón Garrido, B. (2009). Determination of diquat by flow injection-chemiluminescence. Analytical and Bioanalytical Chemistry. 394(4):1073-1079. doi:10.1007/s00216-009-2609-zS107310793944Hayes WJ Jr, Laws ER Jr (1991) Handbook of pesticide toxicology, Academic Press, San DiegoUS Environmental Protection Agency. http://www.epa.gov/06WDW/contaminants/dw_contamfs/diquat.html (accessed in August 2008)Horwitz W (2000) Official methods of analysis of AOAC International 17th edition. AOAC International, Gaithersburg, MD, USAHara S, Sasaki N, Takase D, Shiotsuka S, Ogata K, Futagami K, Tamura K (2007) Anal Sci 23(5):523–531Rial Otero R, Cancho Grande B, Pérez Lamela C, Simal Gandara J, Aria Estevez M (2006) J Chromatogr Sci 44(9):539–542Aramendia MA, Borau V, Lafont F, Marinas JM, Moreno JM, Porras JM, Urbano FJ (2006) Food Chem 97(1):181–188Nuñez O, Moyano E, Galceran MT (2004) Anal Chim Acta 525(2):183–190Martinez Vidal JL, Belmonte Vega A, Sanchez Lopez FJ, Garrido Frenich AJ (2004) Chromatogr A 1050(2):179–184Lee XP, Kumazawa T, Fujishiro M, Hasegawa C, Arinobu T, Seno H, Sato K (2004) J Mass Spectrom 39(10):1147–1152De Almeida RM, Yonamine M (2007) J Chromatogr B 853(1–2):260–264De Souza D, Machado SAS (2006) Electroanalysis 18(9):862–872De Souza D, Da Silva MRC, Machado SAS (2006) Electroanalysis 18(23):2305–2313Picó Y, Rodriguez R, Manes J (2003) Trends Anal Chem 22(3):133–151Ishiwata T (2004) Bunseki Kagaku 53(8):863–864Carneiro MC, Puignou L, Galcerán MT (2000) Anal Chim Acta 408:263Luque M, Rios A, Valcarcel M (1998) Analyst 123(11):2383–2387Perez Ruiz T, Martínez Lozano C, Tomas V (1991) Int J Environ Anal Chem 44(4):243–252Perez Ruiz T, Martínez Lozano C, Tomas V (1991) Anal Chim Acta 244(1):99–104Townshend A (1990) Analyst 115:495–500López Paz JL, Catalá Icardo M (2008) Anal Chim Acta 625:173–179Pawlicová Z, Sahuquillo I, Catalá Icardo M, García Mateo JV, Martínez Calatayud J (2006) Anal Sci 22:29–34Albert García JR, Catalá Icardo M, Martínez Calatayud J (2006) Talanta 69:608–614Tomlin CDS (1997) The pesticide manual, 11th edn.The British Crop Protection CouncilUKCatalá-Icardo M, Martínez-Calatayud J (2008) Crit Rev Anal Chem 38:118–130Ministerio de Medio Ambiente y Medio Rural y Marino. http://www.marm.es/ (accessed in September 2008)US Environmental Protection Agency. http://www.epa.gov/OGWWDW/contaminants (accessed in October 2008
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
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