Simulation of the Perfusion of Contrast Agent Used in Cardiac Magnetic Resonance: A Step Toward Non-invasive Cardiac Perfusion Quantification

This work presents a new mathematical model to describe cardiac perfusion in the myocardium as acquired by cardiac magnetic resonance (CMR) perfusion exams. The combination of first pass (or contrast-enhanced CMR) and late enhancement CMR is a widely used non-invasive exam that can identify abnormal perfused regions of the heart via the use of a contrast agent (CA). The exam provides important information to the diagnosis, management, and prognosis of ischemia and infarct: perfusion on different regions, the status of microvascular structures, the presence of fibrosis, and the relative volume of extracellular space. This information is obtained by inferring the spatiotemporal dynamics of the contrast in the myocardial tissue from the acquired images. The evaluation of these physiological parameters plays an important role in the assessment of myocardial viability. However, the nature of cardiac physiology poses great challenges in the estimation of these parameters. Briefly, these are currently estimated qualitatively via visual inspection of images and comparison of relative brightness between different regions of the heart. Therefore, there is a great urge for techniques that can help to quantify cardiac perfusion. In this work, we propose a new mathematical model based on multidomain flow in porous media. The model is based on a system of partial differential equations. Darcy's law is used to obtain the pressure and velocity distribution. CA dynamics is described by reaction-diffusion-advection equations in the intravascular space and in the interstitial space. The interaction of fibrosis and the CA is also considered. The new model treats the domains as anisotropic media and imposes a closed loop of intravascular flow, which is necessary to reproduce the recirculation of the CA. The model parameters were adjusted to reproduce clinical data. In addition, the model was used to simulate different scenarios: normal perfusion; endocardial ischemia due to stenosis in a coronary artery in the epicardium; and myocardial infarct. Therefore, the computational model was able to correlate anatomical features, stenosis and the presence of fibrosis, with functional ones, cardiac perfusion. Altogether, the results suggest that the model can support the process of non-invasive cardiac perfusion quantification

Ants (Hymenoptera, Formicidae) of APA Pandeiros: A Perspective from a Decade of Research in an Environmental Protection Area in the Cerrado-Caatinga Transition

Habitat transformation and species loss bring enormous environmental damage, whereas establishing protected areas promotes more sustainable use of environmental resources through biodiversity conservation. In this study, we aimed to point out gaps in ant knowledge and provide a species checklist that contributes to biodiversity conservation in the transition areas between Cerrado and Caatinga biomes, constantly threatened by land use changes. This checklist integrates data from previous studies developed at “Área de Proteção Ambiental do Rio Pandeiros” (APA Pandeiros), Minas Gerais, Brazil, involving ant diversity and their contribution to ecological processes accessed and described in the studies. We showed and discussed how authors managed and provided information regarding methodologies and habitats sampled. We listed 143 ant species formally named. Pheidole, Camponotus and Cephalotes were the most speciose genera, with more than ten species each. Among ants involved in ecological processes, 40 are linked to diaspore removal (part of seed dispersal) and 30 to carcass interaction (part of the decomposition process). Unbaited pitfall traps, epigeic stratum and Cerrado sensu stricto, were the top sampling method, stratum, and habitats among ant studies. We presented proposals for the best management and integration of data from surveys in APA Pandeiros (e.g., sharing the results of the studies with the APA managers, creating a database, and the local community). These surveys are fundamental for understanding biodiversity and ecological processes and provide valuable information to conservation biology. Therefore, neglecting the importance of the Cerrado-Caatinga transition can lead to irreparable setbacks for scientific knowledge and biodiversity

Knocking Down Low Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) Reverts Chemoresistance through Inactivation of Src and Bcr-Abl Proteins

The development of multidrug resistance (MDR) limits the efficacy of continuous chemotherapeutic treatment in chronic myelogenous leukemia (CML). Low molecular weight protein tyrosine phosphatase (LMW-PTP) is up-regulated in several cancers and has been associated to poor prognosis. This prompted us to investigate the involvement of LMW-PTP in MDR. In this study, we investigated the role of LMW-PTP in a chemoresistant CML cell line, Lucena-1. Our results showed that LMW-PTP is highly expressed and 7-fold more active in Lucena-1 cells compared to K562 cells, the non-resistant cell line. Knocking down LMW-PTP in Lucena-1 cells reverted chemoresistance to vincristine and imatinib mesylate, followed by a decrease of Src and Bcr-Abl phosphorylation at the activating sites, inactivating both kinases. On the other hand, overexpression of LMW-PTP in K562 cells led to chemoresistance to vincristine. Our findings describe, for the first time, that LMW-PTP cooperates with MDR phenotype, at least in part, through maintaining Src and Bcr-Abl kinases in more active statuses. These findings suggest that inhibition of LMW-PTP may be a useful strategy for the development of therapies for multidrug resistant CML

Callus induction and bioactive phenolic compounds production from Byrsonima verbascifolia (L.) DC. (Malpighiaceae)

ABSTRACT -This study developed a methodology for callus induction in leaf segments of B. verbascifolia and evaluated the bioactive phenolic compounds production. Leaf explants were cultured in MS medium with 30 g L -1 sucrose, solidified with 7 g L -1 agar supplemented with 2,4-D (0; 4.52; 9.05; 18.10 M) and BAP (0; 4.44; 8.88; 17.75 M ) in the presence and absence of light. Forty-five days after inoculation we assessed the percentage of callus induction, color, consistency, fresh and dry matter, total phenols, flavonoids, tannins contents, and chromatographic profile by HPLC-DAD method. Callus induction occurred only in medium with growth regulators. Maximal induction (100%) was found in medium containing 2,4-D combined with BAP in the presence and absence of light. We obtained friable and compact callus in yellow, green, and red. Culture media containing 4.52 M 2,4-D + 4.44 M BAP induced 100% of friable callus with higher fresh and dry weight in the absence of light. The callus produced higher amounts of total phenols and flavonoids than the initial explant

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected