Showing papers by "National University of La Plata published in 2009"

Profiling translatomes of discrete cell populations resolves altered cellular priorities during hypoxia in Arabidopsis.

Abstract: Multicellular organs are composed of distinct cell types with unique assemblages of translated mRNAs. Here, ribosome-associated mRNAs were immunopurified from specific cell populations of intact seedlings using Arabidopsis thaliana lines expressing a FLAG-epitope tagged ribosomal protein L18 (FLAG-RPL18) via developmentally regulated promoters. The profiling of mRNAs in ribosome complexes, referred to as the translatome, identified differentially expressed mRNAs in 21 cell populations defined by cell-specific expression of FLAG-RPL18. Phloem companion cells of the root and shoot had the most distinctive translatomes. When seedlings were exposed to a brief period of hypoxia, a pronounced reprioritization of mRNA enrichment in the cell-specific translatomes occurred, including a ubiquitous rise in 49 mRNAs encoding transcription factors, signaling proteins, anaerobic metabolism enzymes, and uncharacterized proteins. Translatome profiling also exposed an intricate molecular signature of transcription factor (TF) family member mRNAs that was markedly reconfigured by hypoxia at global and cell-specific levels. In addition to the demonstration of the complexity and plasticity of cell-specific populations of ribosome-associated mRNAs, this study provides an in silico dataset for recognition of differentially expressed genes at the cell-, region-, and organ-specific levels.

Increasing arterial blood pressure with norepinephrine does not improve microcirculatory blood flow: a prospective study

Abstract: Introduction Our goal was to assess the effects of titration of a norepinephrine infusion to increasing levels of mean arterial pressure (MAP) on sublingual microcirculation. Methods Twenty septic shock patients were prospectively studied in two teaching intensive care units. The patients were mechanically ventilated and required norepinephrine to maintain a mean arterial pressure (MAP) of 65 mmHg. We measured systemic hemodynamics, oxygen transport and consumption (DO 2 and VO 2 ), lactate, albumin-corrected anion gap, and gastric intramucosal-arterial PCO2 difference (ΔPCO2). Sublingual microcirculation was evaluated by sidestream darkfield (SDF) imaging. After basal measurements at a MAP of 65 mmHg, norepinephrine was titrated to reach a MAP of 75 mmHg, and then to 85 mmHg. Data were analyzed using repeated measurements ANOVA and Dunnett test. Linear trends between the different variables and increasing levels of MAP were calculated. Results Increasing doses of norepinephrine reached the target values of MAP. The cardiac index, pulmonary pressures,

Isolation and characterization of endophytic plant growth-promoting (PGPB) or stress homeostasis-regulating (PSHB) bacteria associated to the halophyte Prosopis strombulifera.

Abstract: This study was designed to isolate and characterize endophytic bacteria from halophyte Prosopis strombulifera grown under extreme salinity and to evaluate in vitro the bacterial mechanisms related to plant growth promotion or stress homeostasis regulation. Isolates obtained from P. strombulifera were compared genotypically by BOX-polymerase chain reaction, grouped according to similarity, and identified by amplification and partial sequences of 16S DNAr. Isolates were grown until exponential growth phase to evaluate the atmospheric nitrogen fixation, phosphate solubilization, siderophores, and phytohormones, such as indole-3-acetic acid, zeatin, gibberellic acid and abscisic acid production, as well as antifungal, protease, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. A total of 29 endophytic strains were grouped into seven according to similarity. All bacteria were able to grow and to produce some phytohormone in chemically defined medium with or without addition of a nitrogen source. Only one was able to produce siderophores, and none of them solubilized phosphate. ACC deaminase activity was positive for six strains. Antifungal and protease activity were confirmed for two of them. In this work, we discuss the possible implications of these bacterial mechanisms on the plant growth promotion or homeostasis regulation in natural conditions.

Single Conical Nanopores Displaying pH-Tunable Rectifying Characteristics. Manipulating Ionic Transport With Zwitterionic Polymer Brushes

Abstract: In this work we describe for the first time the integration of "smart" polymer brushes into single conical nanopores to obtain a new highly functional signal-responsive chemical nanodevice The responsive brushes were constituted of zwitterionic monomers whose charge is regulated via pH changes in the environmental conditions The pH-dependent chemical equilibrium of the monomer units provides a fine-tuning of the ionic transport though the nanopore by simply presetting the pH of the electrolyte solution Our results demonstrate that this strategy enables a higher degree of control over the rectification properties when compared to the nanochannels modified with charged monolayer assemblies We envision that these results will create completely new avenues to build-up "smart" nanodevices using responsive polymer brushes integrated into single conical nanopores

Multifaceted Determinants for Achieving Glycemic Control: The International Diabetes Management Practice Study (IDMPS)

Abstract: OBJECTIVE—The International Diabetes Mellitus Practice Study is a 5-year survey documenting changes in diabetes treatment practice in developing regions. RESEARCH DESIGN AND METHODS—Logistic regression analysis was used to identify factors for achieving A1C <7% in 11,799 patients (1,898 type 1 diabetic and 9,901 type 2 diabetic) recruited by 937 physicians from 17 countries in Eastern Europe (n = 3,519), Asia (n = 5,888), Latin America (n = 2,116), and Africa (n = 276). RESULTS—Twenty-two percent of type 1 diabetic and 36% of type 2 diabetic patients never had A1C measurements. In those with values for A1C, blood pressure, and LDL cholesterol, 7.5% of type 1 diabetic (n = 696) and 3.6% of type 2 diabetic (n = 3,896) patients attained all three recommended targets (blood pressure <130/80 mmHg, LDL cholesterol <100 mg/dl, and A1C <7%). Self-monitoring of blood glucose was the only predictor for achieving the A1C goal in type 1 diabetes (odds ratios: Asia 2.24, Latin America 3.55, and Eastern Europe 2.42). In type 2 diabetes, short disease duration (Asia 0.97, Latin America 0.97, and Eastern Europe 0.82) and treatment with few oral glucose–lowering drugs (Asia 0.64, Latin America 0.76, and Eastern Europe 0.62) were predictors. Other region-specific factors included lack of microvascular complications and old age in Latin America and Asia; health insurance coverage and specialist care in Latin America; lack of obesity and self-adjustment of insulin dosages in Asia; and training by a diabetes educator, self-monitoring of blood glucose in patients who self-adjusted insulin, and lack of macrovascular complications in Eastern Europe. CONCLUSIONS—In developing countries, factors pertinent to patients, doctors, and health care systems all impact on glycemic control.

Quantum quench dynamics of the Luttinger model

Abstract: The dynamics of the Luttinger model after a quantum quench is studied. We compute in detail one- and two-point correlation functions for two types of quenches: from a noninteracting to an interacting Luttinger model and vice versa. In the former case, the noninteracting Fermi gas features in the momentum distribution and other correlation functions are destroyed as time evolves. In the infinite-time limit, equal-time correlations are power laws but the critical exponents are found to differ from their equilibrium values. In all cases, we find that these correlations are well described by a generalized Gibbs ensemble [M. Rigol, V. Dunjko, V. Yurovsky, and M. Olshanii, Phys. Rev. Lett. 98, 050405 (2007)], which assigns a momentum-dependent temperature to each eigenmode.

Forbidden patterns, permutation entropy and stock market inefficiency

Abstract: In this paper we introduce two new quantifiers for the stock market inefficiency: the number of forbidden patterns and the normalized permutation entropy. They are model-independent measures, thus they have more general applicability. We find robust evidence that degree of market inefficiency is positively correlated with the number of forbidden patterns and negatively correlated with the permutation entropy. Our empirical results suggest that these two physical tools are useful to discriminate the stage of stock market development and can be easily implemented.

Contribution of cell wall degrading enzymes to pathogenesis of Fusarium graminearum: a review.

Abstract: Plant-pathogenic fungi produce an array of extracellular hydrolytic enzymes that enable them to penetrate and infect the host tissue; these enzymes are collectively called cell wall-degrading enzymes (CWDE). They may contribute to pathogenesis by degrading wax, cuticle and cell walls, thus aiding tissue invasion and pathogen dissemination. Furthermore, they can act as elicitors of host defense reaction.Fusarium head blight (FHB) is a disease caused principally by Fusarium graminearum on crops, occurring all over the world. Important economic losses on wheat-growing areas have been registered by altering quality parameters of grains. Significant progress has been made in understanding the infection process from F. graminearum on wheat, based on genomic technologies. The virulence degree of this phytopathogen on crops could arise from differences in the production of extracellular enzymes, factors controlling the establishment of infection.Fusarium graminearum isolates from different geographical areas have been examined, and a combination of morphological and molecular data allowed the division of fungi in diverse groups, which have been related to the variation in pathogenicity. In most studied cases there is a correlation between the presence of pectic enzymes, disease symptom and virulence, being also their production decisive in the infection process.

DNA phylogeny reveals polyphyly of Phoma section Peyronellaea and multiple taxonomic novelties

Abstract: Species of the anamorph genus Phoma are commonly isolated from a wide range of ecological niches. They are notoriously difficult to identify due to the paucity of morphological features and the plasticity of these when cultivated on agar media. Species linked to Phoma section Peyronellaea are typified by the production of dictyochlamydospores and thus have additional characters to use in taxon delineation. However, the taxonomy of this section is still not fully understood. Furthermore the production of such chlamydospores also is known in some other sections of Phoma. DNA sequences were generated from three loci, namely ITS, actin, and 3-tubulin, to clarify the phylogeny of Phoma taxa that produce dictyochlamydospores. Results were unable to support section Peyronellaea as a taxonomic entity. Dictyochlamydospore formation appears to be a feature that developed, or was lost, many times during the evolution of Phoma. Furthermore, based on the multigene analyses, five new Phoma species could be delineated while a further five required taxonomic revision to be consistent with the genetic variation observed.

WHO Scientific Update on trans fatty acids: summary and conclusions

Abstract: The purpose of the WHO scientific review on trans fatty acids (TFAs) was to examine the evidence generated since the 1993 Joint FAO/WHO Expert Consultation on Fats and Oils in Human Nutrition, and to inform member countries on the health consequences of TFAs consumption that have emerged since the last report was released. The new information was deemed sufficient to recommend the need to significantly reduce or to virtually eliminate industrially produced TFA from the food supply in agreement with the implementation of the 2004 WHO Global Strategy on Diet, Physical Activity and Health. This goal has been accomplished in some countries and cities, by the virtual elimination of partially hydrogenated vegetable oils in the human food supply, replacing them with healthy cis-unsaturated fatty acids. The document provides the evidence base to promote discussion between the international scientific community related to nutrition and health as well as between agriculturalists, food producers, relevant health professionals, national and international food regulatory agencies, civil society and the private sector to achieve the stated goal.

Semi-empirical white dwarf initial-final mass relationships: a thorough analysis of systematic uncertainties due to stellar evolution models

Abstract: Using the most recent results about white dwarfs (WDs) in ten open clusters, we revisit semiempirical estimates of the initial-final mass relation (IFMR) in star clusters, with emphasis on the use of stellar evolution models. We discuss the influence of these models on each step of the derivation. One intention of our work is to use consistent sets of calculations both for the isochrones and the WD cooling tracks. The second one is to derive the range of systematic errors arising from stellar evolution theory. This is achieved by using different sources for the stellar models and by varying physical assumptions and input data. We find that systematic errors, including the determination of the cluster age, are dominating the initial mass values, while observational uncertainties influence the final mass primarily. After having determined the systematic errors, the initial-final mass relation allows us finally to draw conclusions about the physics of the stellar models, in particular about convective overshooting.

Approaches to removing trans fats from the food supply in industrialized and developing countries

Abstract: A number of approaches have been initiated by governmental and public health organizations in different countries to reduce trans-fatty acid (TFA) intakes. These have included nutrition recommendations with regard to TFAs and general nutrition recommendations regarding the selection of healthy fats, programmes to raise awareness about the adverse effects of TFAs through nutrition and health claims, voluntary or mandatory labelling of the trans content of foods, voluntary or legislated programmes to encourage or force industry to reformulate food products to remove TFAs, the promotion of health and agricultural policies that encourage the production of healthy alternatives to trans fat and finally, mandatory regulation of food standards to remove or reduce the TFA content. This paper reviews a number of initiatives to reduce the intake of TFAs underway in selected industrialized and developing countries, which serves to illustrate the merits and limitations of the available options and how the approaches that have been taken reflect local conditions.

Sliding Mode Strategy for PEM Fuel Cells Stacks Breathing Control Using a Super-Twisting Algorithm

Abstract: A second-order sliding mode strategy to control the breathing subsystem of a polymer electrolyte membrane fuel cell stack for transportation applications is presented. The controller is developed from a design model of the plant derived from open literature, and well suited for the design of second-order sliding mode strategies. Stability issues are solved using a super twisting algorithm. The resulting approach exhibits good dynamic characteristics, being robust to uncertainties and disturbances. Simulations results are provided, showing the feasibility of the approach.

Equivalent viscoelastic solids for heterogeneous fluid-saturated porous rocks

Abstract: Differenttheoreticalandlaboratorystudiesonthepropagation ofelasticwavesinrealrockshaveshownthatthepresenceofheterogeneities larger than the pore size but smaller than the predominant wavelengths mesoscopic-scale heterogeneities may producesignificantattenuationandvelocitydispersioneffectson seismic waves. Such phenomena are known as “mesoscopic effects” and are caused by equilibration of wave-induced fluid pressure gradients.We propose a numerical upscaling procedure to obtain equivalent viscoelastic solids for heterogeneous fluidsaturated rocks. It consists in simulating oscillatory compressibility and shear tests in the space-frequency domain, which enable us to obtain the equivalent complex undrained plane wave and shear moduli of the rock sample. We assume that the behavior of the porous media obeys Biot’s equations and use a finiteelementproceduretoapproximatethesolutionsoftheassociated boundary value problems. Also, because at mesoscopic scales rock parameter distributions are generally uncertain and of stochastic nature, we propose applying the compressibility and sheartestsinaMonteCarlofashion.Thisfacilitatesthedefinition of average equivalent viscoelastic media by computing the moments of the equivalent phase velocities and inverse quality factors over a set of realizations of stochastic rock parameters described by a given spectral density distribution.We analyzed the sensitivity of the mesoscopic effects to different kinds of heterogeneities in the rock and fluid properties using numerical examples.Also,theapplicationoftheMonteCarloprocedureallowed us to determine the statistical properties of phase velocities and inverse quality factors for the particular case of quasi-fractal heterogeneities.

Increased asthma and respiratory symptoms in children exposed to petrochemical pollution

Abstract: Background Epidemiologic studies show statistical associations between levels of air pollutants and respiratory outcomes. Objective We sought to determine the effects of exposure to petrochemical pollution on the respiratory health of children. Methods Children aged 6 to 12 years living close to the petrochemical plants in La Plata, Argentina (n = 282), were compared with those living in a region with exposure to heavy traffic (n = 270) or in 2 relatively nonpolluted areas (n = 639). Parents answered a validated questionnaire providing health and demographic data. A random sample (n = 181) had lung function measured. Particulate matter and outdoor and indoor volatile organic compound levels were measured during 4-week study periods and reported as overall means for each study area. Results Children living near the petrochemical plant had more asthma (24.8% vs 10.1% to 11.5%), more asthma exacerbations (6.7 vs 2.9-3.6 per year), more respiratory symptoms (current wheeze, dyspnea, nocturnal cough, and rhinitis), and lower lung function (>13% decrease in FEV 1 percent predicted) than those living in other regions. Length of residence in the area was a significant risk factor, but age, sex, body mass index, proximity to busy roads and other nonpetrochemical industries, length of breast-feeding, and socioeconomic and demographic characteristics of children or their families were not. Conclusion Exposure to particulate matter and volatile organic compounds arising from petrochemical plants but not from high traffic density was associated ith worse respiratory health in children.

Biochronological relationships of the earliest south american paleogene mammalian faunas

Abstract: The oldest Cenozoic mammalian assemblages in South America have been recovered from levels of the Han- sen Member of the Salamanca Formation, Punta Peligro locality in Argentina, and from the Santa Lucia Formation in Tiupampa, Bolivia. These faunas led to the recognition of the Peligran and Tiupampan South American Land Mammal Ages (SALMAs), each alternatively regarded as the oldest Paleocene SALMA. Due to the lack of radioisotopic dates for mammals bearing levels at these localities, no agreement has been reached yet about their relative ages. In this paper, the role of mammal faunas in age inference is discussed. Analysis of the SALMAs shows that the presence of non-therian mammals in the Peligran is of little consequence to the bio- chronological evaluation, reflecting instead a relict Mesozoic distribution. In contrast, therian mammals are particularly important in that (1) they were Lauraisan immigrants and (2) they support direct comparisons between the Tiupampa and Punta Peligro faunas. Parsimony and cluster analysis were used to quantitatively test hypotheses concerning the relative age of the Peligran and Tiupampan SALMAs. Our results support the hypothesis that the Tiupampan SALMA (early Danian) is older than the Peligran SALMA (early Selandian). This alignment results in an interpretation of the evolutionary history of South American land mammals that is more straightforward than the alternative.

TP53 codon 72 polymorphism and cervical cancer: a pooled analysis of individual data from 49 studies

Abstract: Summary Background Cervical cancer is caused primarily by human papillomaviruses (HPV). The polymorphism rs1042522 at codon 72 of the TP53 tumour-suppressor gene has been investigated as a genetic cofactor. More than 80 studies were done between 1998 and 2006, after it was initially reported that women who are homozygous for the arginine allele had a risk for cervical cancer seven times higher than women who were heterozygous for the allele. However, results have been inconsistent. Here we analyse pooled data from 49 studies to determine whether there is an association between TP53 codon 72 polymorphism and cervical cancer. Methods Individual data on 7946 cases and 7888 controls from 49 different studies worldwide were reanalysed. Odds ratios (OR) were estimated using logistic regression, stratifying by study and ethnic origin. Subgroup analyses were done for infection with HPV, ethnic origin, Hardy–Weinberg equilibrium, study quality, and the material used to determine TP53 genotype. Findings The pooled estimates (OR) for invasive cervical cancer were 1·22 (95% CI 1·08–1·39) for arginine homozygotes compared with heterozygotes, and 1·13 (0·94–1·35) for arginine homozygotes versus proline homozygotes. Subgroup analyses showed significant excess risks only in studies where controls were not in Hardy–Weinberg equilibrium (1·71 [1·21–2·42] for arginine homozygotes compared with heterozygotes), in non-epidemiological studies (1·35 [1·15–1·58] for arginine homozygotes compared with heterozygotes), and in studies where TP53 genotype was determined from tumour tissue (1·39 [1·13–1·73] for arginine homozygotes compared with heterozygotes). Null results were noted in studies with sound epidemiological design and conduct (1·06 [0·87–1·29] for arginine homozygotes compared with heterozygotes), and studies in which TP53 genotype was determined from white blood cells (1·06 [0·87–1·29] for arginine homozygotes compared with heterozygotes). Interpretation Subgroup analyses indicated that excess risks were most likely not due to clinical or biological factors, but to errors in study methods. No association was found between cervical cancer and TP53 codon 72 polymorphism when the analysis was restricted to methodologically sound studies. Funding German Research Foundation (DFG).

Angiotensin II–Induced Oxidative Stress Resets the Ca2+ Dependence of Ca2+–Calmodulin Protein Kinase II and Promotes a Death Pathway Conserved Across Different Species

Abstract: Rationale: Angiotensin (Ang) II–induced apoptosis was reported to be mediated by different signaling molecules. Whether these molecules are either interconnected in a single pathway or constitute different and alternative cascades by which Ang II exerts its apoptotic action, is not known. Objective: To investigate in cultured myocytes from adult cat and rat, 2 species in which Ang II has opposite inotropic effects, the signaling cascade involved in Ang II–induced apoptosis. Methods and Results: Ang II (1 μmol/L) reduced cat/rat myocytes viability by ≈40%, in part, because of apoptosis (TUNEL/caspase-3 activity). In both species, apoptosis was associated with reactive oxygen species (ROS) production, Ca2+/calmodulin–dependent protein kinase (CaMK)II, and p38 mitogen-activated protein kinase (p38MAPK) activation and was prevented by the ROS scavenger MPG (2-mercaptopropionylglycine) or the NADPH oxidase inhibitor DPI (diphenyleneiodonium) by CaMKII inhibitors (KN-93 and AIP [autocamtide 2-related inhibitory peptide]) or in transgenic mice expressing a CaMKII inhibitory peptide and by the p38MAPK inhibitor, SB202190. Furthermore, p38MAPK overexpression exacerbated Ang II–induced cell mortality. Moreover, although KN-93 did not affect Ang II–induced ROS production, it prevented p38MAPK activation. Results further show that CaMKII can be activated by Ang II or H2O2, even in the presence of the Ca2+ chelator BAPTA-AM, in myocytes and in EGTA-Ca2+–free solutions in the presence of the calmodulin inhibitor W-7 in in vitro experiments. Conclusions: (1) The Ang II–induced apoptotic cascade converges in both species, in a common pathway mediated by ROS-dependent CaMKII activation which results in p38MAPK activation and apoptosis. (2) In the presence of Ang II or ROS, CaMKII may be activated at subdiastolic Ca2+ concentrations, suggesting a new mechanism by which ROS reset the Ca2+ dependence of CaMKII to extremely low Ca2+ levels.